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1,316,223 | My CPU cooler is too big so i cant get my motherboard out to clean it it's like 7 years old and I need to get the dust out. I have tried to take it out without taking off the motherboard but it doesn't fit. | 2018/04/22 | [
"https://superuser.com/questions/1316223",
"https://superuser.com",
"https://superuser.com/users/897689/"
] | **That is a bad idea! Continue reading...**
You need physical contact to move heat efficiently from the **CPU** heatspreader to the heatsink. The role of **thermal paste** is to "fill in the gaps" and allow for better transfer of heat from the heatspreader to the heatsink.
**What will happen if I don't put a thermal paste in my processor and heatsink?**
Things don't work as efficiently as they should. Your CPU's operating temperature will be higher. It may need to slow itself down (thermal throttling) to stop from overheating and failing.
Does this mean that your CPU will burn out and die? No. Does it mean that it is more likely to? Yes. Does it mean that your CPU will throttle? No. Does it mean that it is more likely to? Yes. Can you run your CPU without thermal paste for years and still have an operating computer? Yes. Is it a good idea to try? No.
The truth is that properly applied thermal paste is an important component of a cooling system and going without it is a *bad idea*. It's also a good idea to service your CPU every now and then (once every year or two) and replace dried and cracked thermal compound with a fresh application. If you find that thermal paste wasn't applied to your CPU when it was assembled, that's bad, but it isn't the end of the world. Modern CPUs will attempt to shut down before reaching a temperature at which damage occurs, and before that, they will slow themselves down. | Why remove the heatsink?
Purchase an air duster (compressed air, or a blower designed for the same role) to blow the dust out of your case. Less work involved, and no need to worry about damaging your system\*
\*don't blow the fans - preferably hold them in place while cleaning. This prevents them from spinning up and acting as a turbine generating power. |
1,316,223 | My CPU cooler is too big so i cant get my motherboard out to clean it it's like 7 years old and I need to get the dust out. I have tried to take it out without taking off the motherboard but it doesn't fit. | 2018/04/22 | [
"https://superuser.com/questions/1316223",
"https://superuser.com",
"https://superuser.com/users/897689/"
] | Yes, you should replace the compound if you remove the heatsink.
Thermal paste is generally either a near-fluid or putty like compound when applied. Over time it "sets" into a solid due to heat and forms an effective seal between the CPU case and heatsink.
When you remove the heatsink you break that seal and create gaps in the compound. As the compound is no longer malleable it cannot reflow into gaps when you refit the heatsink and can easily end up with air bubbles and poor contact between the CPU and heatsink. | Why remove the heatsink?
Purchase an air duster (compressed air, or a blower designed for the same role) to blow the dust out of your case. Less work involved, and no need to worry about damaging your system\*
\*don't blow the fans - preferably hold them in place while cleaning. This prevents them from spinning up and acting as a turbine generating power. |
55,196 | I hope that this question follows the rules.
One of my characters has a kalimba that, when played, allows the player to hear the thoughts of everyone around them, and everyone around them can hear the player's thoughts. These thoughts can also control each other, so everyone involved can make each other do anything they want by telling them to do it through their thoughts, like mind control.
It's kind of like an addiction, though, and the more that you play it, the deeper you get in said "addiction". The idea of an addictive magical item sounds kinda familiar, though... (cough One Ring cough)... at least, to me, it does. (Note: All magic is addictive, and the higher magic something has, the more addictive it is.)
It only works if the correct three moons are in the sky (this world has multiple moons); otherwise, it's a completely normal kalimba.
Is this too cliche, or should I keep it as it is? | 2021/03/09 | [
"https://writers.stackexchange.com/questions/55196",
"https://writers.stackexchange.com",
"https://writers.stackexchange.com/users/49102/"
] | **It is *not* cliche:**
Like I mentioned in comments, every good idea has been used before. Just by using a vague idea (an addictive magical item) and it happens that a different book with a *different* plot has also used a similar thing doesn't make your idea cliche.
When you say "addictive magical item" cliche doesn't come to mind, at all.
So, as long as you research books with similar items to make sure your item is not too similar (which I doubt it will be) and then you make any necessary changes, you should be fine.
For example, just because [a book has a superhero character](https://www.google.com/search?surl=1&rlz=1CAXEGH_enUS894&ei=JvZHYNTHCMbK-gTSpYuICA&q=books%20with%20a%20superhero&oq=books%20with%20a%20superhero&gs_lcp=Cgdnd3Mtd2l6EAMyBggAEBYQHjoHCAAQRxCwAzoCCAA6CAgAEBYQChAeOggILhDHARCjAjoHCCEQChCgAVDKkgFYzPYBYLv5AWgKcAF4AIABxwSIAeEXkgEMMi4xMS4yLjAuMS4xmAEAoAEBqgEHZ3dzLXdpesgBBsABAQ&sclient=gws-wiz&ved=0ahUKEwjU8r3doKTvAhVGpZ4KHdLSAoEQ4dUDCA0&uact=5&safe=active&ssui=on) doesn't mean that no other book can have one. | Your magical item is distinct from the One Ring because it simultaneously takes control of others *and grants those others control over you*.
One Kalimba to rule (and be ruled) by all...
Sounds like a lot of new territory to explore in that one. Definitely not cliche'. |
55,196 | I hope that this question follows the rules.
One of my characters has a kalimba that, when played, allows the player to hear the thoughts of everyone around them, and everyone around them can hear the player's thoughts. These thoughts can also control each other, so everyone involved can make each other do anything they want by telling them to do it through their thoughts, like mind control.
It's kind of like an addiction, though, and the more that you play it, the deeper you get in said "addiction". The idea of an addictive magical item sounds kinda familiar, though... (cough One Ring cough)... at least, to me, it does. (Note: All magic is addictive, and the higher magic something has, the more addictive it is.)
It only works if the correct three moons are in the sky (this world has multiple moons); otherwise, it's a completely normal kalimba.
Is this too cliche, or should I keep it as it is? | 2021/03/09 | [
"https://writers.stackexchange.com/questions/55196",
"https://writers.stackexchange.com",
"https://writers.stackexchange.com/users/49102/"
] | Your magical item is distinct from the One Ring because it simultaneously takes control of others *and grants those others control over you*.
One Kalimba to rule (and be ruled) by all...
Sounds like a lot of new territory to explore in that one. Definitely not cliche'. | What seems the underlying mechanism of the Kalimba is to bring multiple people together into a singular hive mind, regardless of who's actually playing. (The way you've described this the person playing isn't conferred any particular "power" over the others in earshot.)
On that note, what you have is something that's addictive not because it bestows power, but togetherness. For example for characters who are stoic and difficult to open up, it could be this thought-sharing would be enticing since thoughts are more abstract than words.
I wouldn't consider this is a cliché simply because the addictive mechanism is different. |
55,196 | I hope that this question follows the rules.
One of my characters has a kalimba that, when played, allows the player to hear the thoughts of everyone around them, and everyone around them can hear the player's thoughts. These thoughts can also control each other, so everyone involved can make each other do anything they want by telling them to do it through their thoughts, like mind control.
It's kind of like an addiction, though, and the more that you play it, the deeper you get in said "addiction". The idea of an addictive magical item sounds kinda familiar, though... (cough One Ring cough)... at least, to me, it does. (Note: All magic is addictive, and the higher magic something has, the more addictive it is.)
It only works if the correct three moons are in the sky (this world has multiple moons); otherwise, it's a completely normal kalimba.
Is this too cliche, or should I keep it as it is? | 2021/03/09 | [
"https://writers.stackexchange.com/questions/55196",
"https://writers.stackexchange.com",
"https://writers.stackexchange.com/users/49102/"
] | **It is *not* cliche:**
Like I mentioned in comments, every good idea has been used before. Just by using a vague idea (an addictive magical item) and it happens that a different book with a *different* plot has also used a similar thing doesn't make your idea cliche.
When you say "addictive magical item" cliche doesn't come to mind, at all.
So, as long as you research books with similar items to make sure your item is not too similar (which I doubt it will be) and then you make any necessary changes, you should be fine.
For example, just because [a book has a superhero character](https://www.google.com/search?surl=1&rlz=1CAXEGH_enUS894&ei=JvZHYNTHCMbK-gTSpYuICA&q=books%20with%20a%20superhero&oq=books%20with%20a%20superhero&gs_lcp=Cgdnd3Mtd2l6EAMyBggAEBYQHjoHCAAQRxCwAzoCCAA6CAgAEBYQChAeOggILhDHARCjAjoHCCEQChCgAVDKkgFYzPYBYLv5AWgKcAF4AIABxwSIAeEXkgEMMi4xMS4yLjAuMS4xmAEAoAEBqgEHZ3dzLXdpesgBBsABAQ&sclient=gws-wiz&ved=0ahUKEwjU8r3doKTvAhVGpZ4KHdLSAoEQ4dUDCA0&uact=5&safe=active&ssui=on) doesn't mean that no other book can have one. | [](https://i.stack.imgur.com/xXZQL.png)
Dog: You want to give me a belly rub. Bard: You don't want to bite the mailman.
Who will win?
The One Ring wasn't addictive, like how opium or tobacco induce a positive experience that repeated use turns into a dependence with diminishing returns.
The invisibility the Ring gave the wearer was addictive since it conferred a sense of power to the user. Repeated use of the ring let the will of Sauron try to corrupt you -- worked on Smeagol, but no so much on Bilbo, two characters that used the ring a lot, and did a number on Frodo despite only wearing the ring once.
I don't think your notion of an addictive magical item is cliche. But, it's hard for me to imagine how the Kamilba would be addictive. Because you lose control of yourself when you gain control over others. That doesn't give me a sense of good times or euphoric bliss that would make someone want to repeat the experience. You make your audience give you all their money and one of them makes you stick your head in the deep fat fryer.
The notion that it only works when 3 moons are in the sky seems like a convenient story mechanic used to explain away how someone gets addicted to playing the instrument without experiencing the cost of being mentally dominated by their audience.
If playing the kalimba gave the musician an empathic sense of the audience, then performance could be tuned to evoke the maximum experience in everyone listening to the music, creating a deep sense of connection between the performer and the audience. The audience would see the musician as the greatest of all time, and I could see the performer getting hooked on both the adulation and deep intimacy. |
55,196 | I hope that this question follows the rules.
One of my characters has a kalimba that, when played, allows the player to hear the thoughts of everyone around them, and everyone around them can hear the player's thoughts. These thoughts can also control each other, so everyone involved can make each other do anything they want by telling them to do it through their thoughts, like mind control.
It's kind of like an addiction, though, and the more that you play it, the deeper you get in said "addiction". The idea of an addictive magical item sounds kinda familiar, though... (cough One Ring cough)... at least, to me, it does. (Note: All magic is addictive, and the higher magic something has, the more addictive it is.)
It only works if the correct three moons are in the sky (this world has multiple moons); otherwise, it's a completely normal kalimba.
Is this too cliche, or should I keep it as it is? | 2021/03/09 | [
"https://writers.stackexchange.com/questions/55196",
"https://writers.stackexchange.com",
"https://writers.stackexchange.com/users/49102/"
] | [](https://i.stack.imgur.com/xXZQL.png)
Dog: You want to give me a belly rub. Bard: You don't want to bite the mailman.
Who will win?
The One Ring wasn't addictive, like how opium or tobacco induce a positive experience that repeated use turns into a dependence with diminishing returns.
The invisibility the Ring gave the wearer was addictive since it conferred a sense of power to the user. Repeated use of the ring let the will of Sauron try to corrupt you -- worked on Smeagol, but no so much on Bilbo, two characters that used the ring a lot, and did a number on Frodo despite only wearing the ring once.
I don't think your notion of an addictive magical item is cliche. But, it's hard for me to imagine how the Kamilba would be addictive. Because you lose control of yourself when you gain control over others. That doesn't give me a sense of good times or euphoric bliss that would make someone want to repeat the experience. You make your audience give you all their money and one of them makes you stick your head in the deep fat fryer.
The notion that it only works when 3 moons are in the sky seems like a convenient story mechanic used to explain away how someone gets addicted to playing the instrument without experiencing the cost of being mentally dominated by their audience.
If playing the kalimba gave the musician an empathic sense of the audience, then performance could be tuned to evoke the maximum experience in everyone listening to the music, creating a deep sense of connection between the performer and the audience. The audience would see the musician as the greatest of all time, and I could see the performer getting hooked on both the adulation and deep intimacy. | What seems the underlying mechanism of the Kalimba is to bring multiple people together into a singular hive mind, regardless of who's actually playing. (The way you've described this the person playing isn't conferred any particular "power" over the others in earshot.)
On that note, what you have is something that's addictive not because it bestows power, but togetherness. For example for characters who are stoic and difficult to open up, it could be this thought-sharing would be enticing since thoughts are more abstract than words.
I wouldn't consider this is a cliché simply because the addictive mechanism is different. |
55,196 | I hope that this question follows the rules.
One of my characters has a kalimba that, when played, allows the player to hear the thoughts of everyone around them, and everyone around them can hear the player's thoughts. These thoughts can also control each other, so everyone involved can make each other do anything they want by telling them to do it through their thoughts, like mind control.
It's kind of like an addiction, though, and the more that you play it, the deeper you get in said "addiction". The idea of an addictive magical item sounds kinda familiar, though... (cough One Ring cough)... at least, to me, it does. (Note: All magic is addictive, and the higher magic something has, the more addictive it is.)
It only works if the correct three moons are in the sky (this world has multiple moons); otherwise, it's a completely normal kalimba.
Is this too cliche, or should I keep it as it is? | 2021/03/09 | [
"https://writers.stackexchange.com/questions/55196",
"https://writers.stackexchange.com",
"https://writers.stackexchange.com/users/49102/"
] | **It is *not* cliche:**
Like I mentioned in comments, every good idea has been used before. Just by using a vague idea (an addictive magical item) and it happens that a different book with a *different* plot has also used a similar thing doesn't make your idea cliche.
When you say "addictive magical item" cliche doesn't come to mind, at all.
So, as long as you research books with similar items to make sure your item is not too similar (which I doubt it will be) and then you make any necessary changes, you should be fine.
For example, just because [a book has a superhero character](https://www.google.com/search?surl=1&rlz=1CAXEGH_enUS894&ei=JvZHYNTHCMbK-gTSpYuICA&q=books%20with%20a%20superhero&oq=books%20with%20a%20superhero&gs_lcp=Cgdnd3Mtd2l6EAMyBggAEBYQHjoHCAAQRxCwAzoCCAA6CAgAEBYQChAeOggILhDHARCjAjoHCCEQChCgAVDKkgFYzPYBYLv5AWgKcAF4AIABxwSIAeEXkgEMMi4xMS4yLjAuMS4xmAEAoAEBqgEHZ3dzLXdpesgBBsABAQ&sclient=gws-wiz&ved=0ahUKEwjU8r3doKTvAhVGpZ4KHdLSAoEQ4dUDCA0&uact=5&safe=active&ssui=on) doesn't mean that no other book can have one. | What seems the underlying mechanism of the Kalimba is to bring multiple people together into a singular hive mind, regardless of who's actually playing. (The way you've described this the person playing isn't conferred any particular "power" over the others in earshot.)
On that note, what you have is something that's addictive not because it bestows power, but togetherness. For example for characters who are stoic and difficult to open up, it could be this thought-sharing would be enticing since thoughts are more abstract than words.
I wouldn't consider this is a cliché simply because the addictive mechanism is different. |
1,933 | Is it possible to create a custom AI in a Starcraft 2 mod? If so, how? | 2010/07/15 | [
"https://gaming.stackexchange.com/questions/1933",
"https://gaming.stackexchange.com",
"https://gaming.stackexchange.com/users/679/"
] | As the new Starcraft editor is very mighty and supports something like procedures and functions you possibly can enhance available AIs with own stuff. For an example create some triggers like "IF player1 has >x units of this and that type, THEN AIPlayer2 order to tech for this tech"
Maybe this style would be a bit too basic, but should be easy to do for non-programmers. | Well I know for the beta there were several AI mods released, so it might be possible. |
1,933 | Is it possible to create a custom AI in a Starcraft 2 mod? If so, how? | 2010/07/15 | [
"https://gaming.stackexchange.com/questions/1933",
"https://gaming.stackexchange.com",
"https://gaming.stackexchange.com/users/679/"
] | As the new Starcraft editor is very mighty and supports something like procedures and functions you possibly can enhance available AIs with own stuff. For an example create some triggers like "IF player1 has >x units of this and that type, THEN AIPlayer2 order to tech for this tech"
Maybe this style would be a bit too basic, but should be easy to do for non-programmers. | Starcraft 2 AIs are written in a scripting language called Galaxy Script.
There are a few custom AIs available (some even openSource) at:
[Startcraft 2 AI Forum](http://darkblizz.org/Forum2/land-of-ai/) |
527,566 | Is there any way through which i can restrict my AIR app to be further distribution?
Say I have make one AIR application and I give this app to my friend. Is there any way so that he can not re distribute this app to any new person? | 2009/02/09 | [
"https://Stackoverflow.com/questions/527566",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/21988/"
] | There's nothing built in that will help you solve this, but two ideas come to mind.
One choice is to require a serial number on first startup. Validate the serial number against a server using HTTPS and then store it, encrypted, in the local store. You could then validate that machine's use of the serial either on the server, or by using something unique to the machine to encrypt the local store.
You could also possibly use client certificates, which would need to be installed on the user machine. The application could then validate against the certificate on startup. | If you restrict your AIR application from distribution, wouldn't that make it impossible for you to give the application to your friend? The only language-agnostic way I can see this be done with any application is that you have your friend come over and have a look on your computer.
If you are keen on making the AIR application "yours" you could try to [sign it digitally](http://www.adobe.com/devnet/air/articles/signing_air_applications_print.html) but getting a certificate costs loads of money. |
527,566 | Is there any way through which i can restrict my AIR app to be further distribution?
Say I have make one AIR application and I give this app to my friend. Is there any way so that he can not re distribute this app to any new person? | 2009/02/09 | [
"https://Stackoverflow.com/questions/527566",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/21988/"
] | There's nothing built in that will help you solve this, but two ideas come to mind.
One choice is to require a serial number on first startup. Validate the serial number against a server using HTTPS and then store it, encrypted, in the local store. You could then validate that machine's use of the serial either on the server, or by using something unique to the machine to encrypt the local store.
You could also possibly use client certificates, which would need to be installed on the user machine. The application could then validate against the certificate on startup. | This is a good question. A possible solution to this is certification. However i have a doubt here. Do you want your friend not to distribute this application + no secondary installation is possible with it.
Secondary installation means if your friends wants his system to format and reinstall the application. Do you want to support this?
If no then solution is easy. |
527,566 | Is there any way through which i can restrict my AIR app to be further distribution?
Say I have make one AIR application and I give this app to my friend. Is there any way so that he can not re distribute this app to any new person? | 2009/02/09 | [
"https://Stackoverflow.com/questions/527566",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/21988/"
] | This is a good question. A possible solution to this is certification. However i have a doubt here. Do you want your friend not to distribute this application + no secondary installation is possible with it.
Secondary installation means if your friends wants his system to format and reinstall the application. Do you want to support this?
If no then solution is easy. | If you restrict your AIR application from distribution, wouldn't that make it impossible for you to give the application to your friend? The only language-agnostic way I can see this be done with any application is that you have your friend come over and have a look on your computer.
If you are keen on making the AIR application "yours" you could try to [sign it digitally](http://www.adobe.com/devnet/air/articles/signing_air_applications_print.html) but getting a certificate costs loads of money. |
233,882 | I used to think that maximum trophies obtainable in multiplayer attacks is 34. Because from my past experiences I have not seen a value greater than 34.
Today while searching for an opponent in multiplayer I came across a village that would yield 40 trophies if I had 3 starred it.(however I was able to make only 2 stars 50%)
So I want to ask : **Is this a bug or the trophies system has changed recently?**
 | 2015/08/31 | [
"https://gaming.stackexchange.com/questions/233882",
"https://gaming.stackexchange.com",
"https://gaming.stackexchange.com/users/90465/"
] | I'm pretty sure the game doesn't let you do this. As Byzantine Emperor, I tried to grant the Bishopric of Alexandria to the Ecumenical Patriarch after I captured it in a holy war, but it wouldn't let me. It didn't even show up in the list titles. I could give him any other bishopric in the Duchy of Alexandria, and I could give the bishopric to someone else, but I couldn't give it to him. It looks like the wiki is out of date and the game now forces the pentarchs to be separate characters. | The titles will stay together, since they have the same succession laws.
But are you able to give all the pentarchies to the Ecummental Patriarch? Following a recent update i noticed that i cannot give more than one duchy to an prince-archbishop, and got the message "Cannot give more than one duchy or kingdom to theocracies" or something similar. |
233,882 | I used to think that maximum trophies obtainable in multiplayer attacks is 34. Because from my past experiences I have not seen a value greater than 34.
Today while searching for an opponent in multiplayer I came across a village that would yield 40 trophies if I had 3 starred it.(however I was able to make only 2 stars 50%)
So I want to ask : **Is this a bug or the trophies system has changed recently?**
 | 2015/08/31 | [
"https://gaming.stackexchange.com/questions/233882",
"https://gaming.stackexchange.com",
"https://gaming.stackexchange.com/users/90465/"
] | There is something you can do: conquer the specified target, as Alexandria. Now, you must own both the province and the Bishopric of Alexandria. Make the Bishopric your primary title then give the county of Alexandria to your Ecumenical Patirach. | The titles will stay together, since they have the same succession laws.
But are you able to give all the pentarchies to the Ecummental Patriarch? Following a recent update i noticed that i cannot give more than one duchy to an prince-archbishop, and got the message "Cannot give more than one duchy or kingdom to theocracies" or something similar. |
233,882 | I used to think that maximum trophies obtainable in multiplayer attacks is 34. Because from my past experiences I have not seen a value greater than 34.
Today while searching for an opponent in multiplayer I came across a village that would yield 40 trophies if I had 3 starred it.(however I was able to make only 2 stars 50%)
So I want to ask : **Is this a bug or the trophies system has changed recently?**
 | 2015/08/31 | [
"https://gaming.stackexchange.com/questions/233882",
"https://gaming.stackexchange.com",
"https://gaming.stackexchange.com/users/90465/"
] | I'm pretty sure the game doesn't let you do this. As Byzantine Emperor, I tried to grant the Bishopric of Alexandria to the Ecumenical Patriarch after I captured it in a holy war, but it wouldn't let me. It didn't even show up in the list titles. I could give him any other bishopric in the Duchy of Alexandria, and I could give the bishopric to someone else, but I couldn't give it to him. It looks like the wiki is out of date and the game now forces the pentarchs to be separate characters. | There is something you can do: conquer the specified target, as Alexandria. Now, you must own both the province and the Bishopric of Alexandria. Make the Bishopric your primary title then give the county of Alexandria to your Ecumenical Patirach. |
38,462 | In the US, which part of the government is holding the money due to federal employees?
During a government shutdown, what happens to this money? Is it reinvested through short-term lending? | 2019/02/01 | [
"https://politics.stackexchange.com/questions/38462",
"https://politics.stackexchange.com",
"https://politics.stackexchange.com/users/2690/"
] | From the perspective of the U.S. Constitution, all of the US government's money is in the Treasury of the United States. Money comes out of there and goes to whoever gets it in accordance with legislation passed by Congress. If there is no such legislation, the money stays there.
While it has become the habit of some people to speak as if the Treasury had compartments of money from which money can go only to certain destinations, where this is the case it is a creation of Congressional law, and not anything in the Constitution. Whatever legal barriers exist are the creation of Congress and can be abolished if Congress makes another law.
All of that money that would have been paid out, if the shutdown had not taken place, is still in the Treasury. | To add on to EvilSnack's answer more on point to what happens to the money in the Treasury viz "reinvestment through short term lending". It would be wonderful if that were the case.... Unfortunately there is little to no money to do that with - to the tune of almost $22T in debt. For a more exact reading see <http://www.usdebtclock.org/#> . What actually happens is the Treasury manages debt re-issuance to meet cash flow trying to hold the least cash safely required. |
3,350 | Is there any free/open or commercial/paid Arduino IDE Sketch Debugger (not Atmel chip factory standard tool set) with Breakpoint and Variable read/set capability?
I read about VM on web. Is there any similar product? | 2014/07/18 | [
"https://arduino.stackexchange.com/questions/3350",
"https://arduino.stackexchange.com",
"https://arduino.stackexchange.com/users/3219/"
] | Those aren't multiplexing chips. Those are just chips to give you more outputs than your arduino has.
The multiplexing is just done on the microcontroller. But it depends on how you are wiring the leds. You can wire the cube to use less digital outputs, but you'll end up with a less bright leds.
You could use no multiplexing. That way the leds are lid with a 100% duty cycle. But for that you'd need 512 outputs.
You can choose to light up only one level at a time. That way you only need 72 outputs (64 for the leds, and 8 for selecting the level). This is a form of multiplexing. Since only one level is lid at a time, the leds have a duty cycle of 12.5%. Please note that because of the way humans perceive light, it will look more like 1/3rd the brightness, instead of 1/8th (so that's great). Also note that since you only need one level to be on at a time, some people prefer to use a decade counter IC for that.
You could also choose to only light one row at a time. That way you only need 24 outputs (8 for the leds, 8 to select which row, 8 to select which level). But you'd need some additional circuitry to combine row- and level-selection.
There are specialized multiplexing IC, but those only support rows and colums (not level). So you need 1 chip for each level, and more problematically you need to run 8-row and 8-culumn wires for each level to the bottom. That's quite a bit of wire, which might ruin the aesthetics of the cube.
In short. There are quite a few ways of making a 8x8x8 cube. I'd suggest finding a well documented build from someone else that you like and follow that.
Quite a bit of information. I hope it's of help. If you have any more question feel free to ask. | You could use a few TLC 5940 PWM Drivers (<http://www.ti.com/product/tlc5940>).
Each one has 16 channels which would mean to power an 8\*8\*8 cube would need 32 Drivers.
However, you can use multiplexing to reduce the number of 5940's you would need.
For example, you could use 4 X 5940's which would give you 64 channels and use 8 X time multiplexing to give you 512 channels.
There are 4096 PWM steps giving you lots of control over brightness and can take up to 17v which should be more than enough for any LED.
One of the added features for the 5940 is because it is a current sink, you dont need a resistor on every LED.
I am currently working on a project with TLC5940's that requires control over 512 RGB LED's meaning I have 1536 individual channels to control |
8,259 | [Global IQ: 1950–2050](http://www.fourmilab.ch/documents/IQ/1950-2050/)
Essentially the idea is that while smart people are getting wealthier, their birth-rate tends to drop. On the other hand poor countries, which are generally populated by less intelligent people, have constant birth rates.
So theoretically this would lead in drops of the global IQ, as the global population is rising. Is this true? | 2012/02/29 | [
"https://skeptics.stackexchange.com/questions/8259",
"https://skeptics.stackexchange.com",
"https://skeptics.stackexchange.com/users/2636/"
] | >
> N.B. IQ scores are standardized for a given population at a given
> time. The average IQ is *always* 100, and its standard deviation is
> *always* 15. To compare between times or populations, we must use “raw IQ,” by which I mean the raw scores of a few tests,
> especially:
>
>
> * [Raven's Matrices](http://en.wikipedia.org/wiki/Raven's), a test of pattern recognition
> * Digit span, a test of short-term memory
>
>
> [It's been discussed
> before](https://skeptics.stackexchange.com/q/2758/5120) whether such
> tests measure intelligence, and whether intelligence even exists. But
> if intelligence does exist, and it increases generation-by-generation as children receive
> better care and nutrition, then Raven's and digit span are
> particularly good tests for showing that increase.
>
>
>
The [Flynn effect](http://www.indiana.edu/~intell/flynneffect.shtml) is a very well-known phenomenon by which the raw IQ of a population *increases* over time. It's been [specifically studied](http://glcrsp.ucdavis.edu/publications/cnp/CNPBrief3.pdf) in rural Kenya, where the paper's authors found that – mainly due to smaller families, better nutrition, and an increased literacy rate among parents – the raw IQ of Kenyan children is increasing, at a rate comparable to that in industrialized nations. As the birth rate decreases and nutrition and literacy improve, that rate will increase. As it rises above the rate in industrialized nations, the "IQ gap" will disappear.
The site you link to ignores the Flynn effect entirely. It takes average raw IQ scores from a few dozen nations, estimates the rest based on “demographic mix,” and then assumes that each nation won't change in intelligence, even for 100 years (despite Flynn's studies having proved an increase). The site hand-waves this, saying that the Flynn effect is “undisputed yet enigmatic” and then arguing that it *doesn't exist*, since:
* It would imply that people in the past were far less intelligent than the current standard, yet “the literature and music of a century or more ago is clearly not the work of marginally retarded minds.”
* Most parents think their children are dumber than they are.
The second isn't worth responding to. The first fundamentally misunderstands the Flynn effect. Let's compare the increase in intelligence to the (better documented) [rise in life expectancy](http://en.wikipedia.org/wiki/Life_expectancy#Human_life_expectancy_patterns). Life expectancy at birth remained at about 30 years for 50 000 years of human history, then skyrocketed at industrialization. The overall trend isn't *people have lived progressively longer throughout history,* but rather *there has been a dramatic increase in life expectancy tied to industrialization.* It's also worth noting that as the average life expectancy rose, *the distribution changed as well,* since most of the change is due to lower infant mortality. Just as today, some people in medieval and ancient times lived to be 90. Similarly, the Flynn effect doesn't imply that *people have gotten more intelligent throughout history,* nor that there weren't any geniuses in the past.
Clearly, intelligence in industrializing nations is growing along with that of industrialized nations. As their HDI increases, the rate of intelligence growth will increase as well. So not only is the world getting *smarter,* but also currently industrializing nations will produce the greatest future gains in aggregate intelligence. | Just the opposite.
The [Flynn Effect](http://www.indiana.edu/~intell/flynneffect.shtml) observes that global IQ scores are actually *increasing* over time at a pretty good clip. The true extent and cause of the effect are a matter of debate (but the effect is more pronounced at the low end of the spectrum, so the theory that increased nutrition and healthcare are a "rising tide that floats all boats" is appealing). |
8,259 | [Global IQ: 1950–2050](http://www.fourmilab.ch/documents/IQ/1950-2050/)
Essentially the idea is that while smart people are getting wealthier, their birth-rate tends to drop. On the other hand poor countries, which are generally populated by less intelligent people, have constant birth rates.
So theoretically this would lead in drops of the global IQ, as the global population is rising. Is this true? | 2012/02/29 | [
"https://skeptics.stackexchange.com/questions/8259",
"https://skeptics.stackexchange.com",
"https://skeptics.stackexchange.com/users/2636/"
] | >
> N.B. IQ scores are standardized for a given population at a given
> time. The average IQ is *always* 100, and its standard deviation is
> *always* 15. To compare between times or populations, we must use “raw IQ,” by which I mean the raw scores of a few tests,
> especially:
>
>
> * [Raven's Matrices](http://en.wikipedia.org/wiki/Raven's), a test of pattern recognition
> * Digit span, a test of short-term memory
>
>
> [It's been discussed
> before](https://skeptics.stackexchange.com/q/2758/5120) whether such
> tests measure intelligence, and whether intelligence even exists. But
> if intelligence does exist, and it increases generation-by-generation as children receive
> better care and nutrition, then Raven's and digit span are
> particularly good tests for showing that increase.
>
>
>
The [Flynn effect](http://www.indiana.edu/~intell/flynneffect.shtml) is a very well-known phenomenon by which the raw IQ of a population *increases* over time. It's been [specifically studied](http://glcrsp.ucdavis.edu/publications/cnp/CNPBrief3.pdf) in rural Kenya, where the paper's authors found that – mainly due to smaller families, better nutrition, and an increased literacy rate among parents – the raw IQ of Kenyan children is increasing, at a rate comparable to that in industrialized nations. As the birth rate decreases and nutrition and literacy improve, that rate will increase. As it rises above the rate in industrialized nations, the "IQ gap" will disappear.
The site you link to ignores the Flynn effect entirely. It takes average raw IQ scores from a few dozen nations, estimates the rest based on “demographic mix,” and then assumes that each nation won't change in intelligence, even for 100 years (despite Flynn's studies having proved an increase). The site hand-waves this, saying that the Flynn effect is “undisputed yet enigmatic” and then arguing that it *doesn't exist*, since:
* It would imply that people in the past were far less intelligent than the current standard, yet “the literature and music of a century or more ago is clearly not the work of marginally retarded minds.”
* Most parents think their children are dumber than they are.
The second isn't worth responding to. The first fundamentally misunderstands the Flynn effect. Let's compare the increase in intelligence to the (better documented) [rise in life expectancy](http://en.wikipedia.org/wiki/Life_expectancy#Human_life_expectancy_patterns). Life expectancy at birth remained at about 30 years for 50 000 years of human history, then skyrocketed at industrialization. The overall trend isn't *people have lived progressively longer throughout history,* but rather *there has been a dramatic increase in life expectancy tied to industrialization.* It's also worth noting that as the average life expectancy rose, *the distribution changed as well,* since most of the change is due to lower infant mortality. Just as today, some people in medieval and ancient times lived to be 90. Similarly, the Flynn effect doesn't imply that *people have gotten more intelligent throughout history,* nor that there weren't any geniuses in the past.
Clearly, intelligence in industrializing nations is growing along with that of industrialized nations. As their HDI increases, the rate of intelligence growth will increase as well. So not only is the world getting *smarter,* but also currently industrializing nations will produce the greatest future gains in aggregate intelligence. | Changes in relative numbers of high-intelligent and low-intelligent people in the world should **never** lead to a change in global IQ.
IQ is not a measure of amount of intelligence, it is a measure of amount of intelligence *relative to peers*.
For example, [see this source:](http://www.iqtestexperts.com/iq-definition.php)
>
> And it is very important for people not to confuse between
> intelligence and relative intelligence. Intelligence can never be
> measured and **IQ is not the measure of intelligence. IQ is simply the
> measure of relative intelligence** derived by a single or set of
> standardized tests.
>
>
>
For example, a young child can have a higher IQ than an adult, even though the adult has plenty more intellectual capacity, because, [the peers of a child](http://www.psychologicaltesting.com/iqtest.htm) are not the same as the peers of an adult:
>
> Modern IQ tests use a "deviation IQ" rather than a ratio IQ. With
> this method, **test takers are referenced to other people of their own
> age**. The average IQ is still 100, but deviations from the average are
> assigned **a number which corresponds to a percentile rank**.
>
>
>
Esentially, *IQ is a measure of ranking*, not of amount of ability. The rankings are expressed in IQ points, which are usually equal to 1/15th of a standard deviation of all possible test-takers.
There are standards for assigning IQs to people who get a certain number of questions correctly. These standards [change over time](http://www.indiana.edu/~intell/flynneffect.shtml#why), so that the average is always 100:
>
> Because populations experience IQ gains over time, **IQ tests must be
> constantly restandardized** so that subjects are not scored against
> inaccurate norms.
>
>
>
That being said, the standards are not updated all the time, and certainly not in all countries. What Lynn and Vanhanen do, in the study that inspired your question, is to give a test that has been standardized [in the Western world](http://cps.nova.edu/~cpphelp/RSPM.html), to nationals of many countries across the globe.
>
> Norms: Norm groups included in the manual are: **British** children
> between the ages of 6 and 16; **Irish** children between the ages of 6 and
> 12; military and civilian subjects between the ages of 20 and 65. A
> supplement includes norms **from Canada**, the **United States**, and **Germany**.
>
>
>
This is the standard that all other people are compared to, when assessing their ranking on the IQ scale.
If the tests were always standardized correctly, that is to (a representative sample of) all potential test-takers, the average global IQ would be 100 every time it is measured. So, no, global IQ should never drop.
But perhaps it does drop? It is, after all, a highly imperfect set of numbers. If global IQ were to drop, we could speculate on the reasons. One of the reasons could be that a putative gap in intelligence between more and less developed countries is widening. This means that the Western standards for assigning IQ points get tougher and tougher for poor, more populous countries. Note that this still doesn't need to mean that global levels of intelligence are dropping! All countries could do better nowadays, but the gap might still widen. Following the pattern of IQ scores over time simply doesn't tell us what is happening with the actual level of intelligence. |
6 | Now that we have this network, I'm sure there'll be newbies coming in asking questions like,
>
> How do I get started with Mozilla/KDE/etc?
>
>
>
or
>
> How do I start contributing to project xyz?
>
>
>
I guess these questions would be very organisation specific, and would spam the network. Would these questions be relevant? | 2015/06/23 | [
"https://opensource.meta.stackexchange.com/questions/6",
"https://opensource.meta.stackexchange.com",
"https://opensource.meta.stackexchange.com/users/66/"
] | Most of these sorts of questions should (and, I think, will) be closed as **too broad**. There are a million different ways to "get started" with something and Stack Exchange is not the platform for that type of discussion. | Both of these questions *feel* like lack of research type questions. Presumably projects that want contributions from others will provide such answers on their web page/CONTRIBUTING/README/etc.
I do not think we should be the switchboard for projects. If a user wants to contribute, they should be visiting the project and looking at their guidelines not asking us to do it for them. |
6 | Now that we have this network, I'm sure there'll be newbies coming in asking questions like,
>
> How do I get started with Mozilla/KDE/etc?
>
>
>
or
>
> How do I start contributing to project xyz?
>
>
>
I guess these questions would be very organisation specific, and would spam the network. Would these questions be relevant? | 2015/06/23 | [
"https://opensource.meta.stackexchange.com/questions/6",
"https://opensource.meta.stackexchange.com",
"https://opensource.meta.stackexchange.com/users/66/"
] | Both of these questions *feel* like lack of research type questions. Presumably projects that want contributions from others will provide such answers on their web page/CONTRIBUTING/README/etc.
I do not think we should be the switchboard for projects. If a user wants to contribute, they should be visiting the project and looking at their guidelines not asking us to do it for them. | These "where do I start" sort of questions will attract opinions and most likely spam (ex. You should start with this). They will be closed for a multitude of reasons. If people want to start and get support for a project, then they should go to the project's existing contributors, or owners.
If we get a bunch of "newbies" asking these sorts of questions, the site could adapt to create a specific reason for closure to send a message to provide well thought out questions if they still apply, or to go directly to the project itself. |
6 | Now that we have this network, I'm sure there'll be newbies coming in asking questions like,
>
> How do I get started with Mozilla/KDE/etc?
>
>
>
or
>
> How do I start contributing to project xyz?
>
>
>
I guess these questions would be very organisation specific, and would spam the network. Would these questions be relevant? | 2015/06/23 | [
"https://opensource.meta.stackexchange.com/questions/6",
"https://opensource.meta.stackexchange.com",
"https://opensource.meta.stackexchange.com/users/66/"
] | Most of these sorts of questions should (and, I think, will) be closed as **too broad**. There are a million different ways to "get started" with something and Stack Exchange is not the platform for that type of discussion. | These "where do I start" sort of questions will attract opinions and most likely spam (ex. You should start with this). They will be closed for a multitude of reasons. If people want to start and get support for a project, then they should go to the project's existing contributors, or owners.
If we get a bunch of "newbies" asking these sorts of questions, the site could adapt to create a specific reason for closure to send a message to provide well thought out questions if they still apply, or to go directly to the project itself. |
6 | Now that we have this network, I'm sure there'll be newbies coming in asking questions like,
>
> How do I get started with Mozilla/KDE/etc?
>
>
>
or
>
> How do I start contributing to project xyz?
>
>
>
I guess these questions would be very organisation specific, and would spam the network. Would these questions be relevant? | 2015/06/23 | [
"https://opensource.meta.stackexchange.com/questions/6",
"https://opensource.meta.stackexchange.com",
"https://opensource.meta.stackexchange.com/users/66/"
] | Most of these sorts of questions should (and, I think, will) be closed as **too broad**. There are a million different ways to "get started" with something and Stack Exchange is not the platform for that type of discussion. | Over at [Programmers.SE](https://softwareengineering.stackexchange.com/), we have already discussed this and covered it in great depth:
* [Where to start?](https://softwareengineering.meta.stackexchange.com/q/6366/22815)
* [Green fields, blue skys, and the white board - what is too broad?](https://softwareengineering.meta.stackexchange.com/q/6961/22815)
The essence of the answers in the linked questions are that:
* Too broad. Good answers would be so long they lose focus and end up being worthless (the opposite of good).
* Unclear. Without enough details to narrow the problem down into something answerable in a reasonable amount of space, the problem statement is a bit fuzzy.
In the context of open source I think asking "which license is right for me given these goals?" would be fine, but the examples you posted are a bit broad and perhaps off-topic (if that is even well-defined in private beta). |
6 | Now that we have this network, I'm sure there'll be newbies coming in asking questions like,
>
> How do I get started with Mozilla/KDE/etc?
>
>
>
or
>
> How do I start contributing to project xyz?
>
>
>
I guess these questions would be very organisation specific, and would spam the network. Would these questions be relevant? | 2015/06/23 | [
"https://opensource.meta.stackexchange.com/questions/6",
"https://opensource.meta.stackexchange.com",
"https://opensource.meta.stackexchange.com/users/66/"
] | Over at [Programmers.SE](https://softwareengineering.stackexchange.com/), we have already discussed this and covered it in great depth:
* [Where to start?](https://softwareengineering.meta.stackexchange.com/q/6366/22815)
* [Green fields, blue skys, and the white board - what is too broad?](https://softwareengineering.meta.stackexchange.com/q/6961/22815)
The essence of the answers in the linked questions are that:
* Too broad. Good answers would be so long they lose focus and end up being worthless (the opposite of good).
* Unclear. Without enough details to narrow the problem down into something answerable in a reasonable amount of space, the problem statement is a bit fuzzy.
In the context of open source I think asking "which license is right for me given these goals?" would be fine, but the examples you posted are a bit broad and perhaps off-topic (if that is even well-defined in private beta). | These "where do I start" sort of questions will attract opinions and most likely spam (ex. You should start with this). They will be closed for a multitude of reasons. If people want to start and get support for a project, then they should go to the project's existing contributors, or owners.
If we get a bunch of "newbies" asking these sorts of questions, the site could adapt to create a specific reason for closure to send a message to provide well thought out questions if they still apply, or to go directly to the project itself. |
11,267 | Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, they can be sure that both of their lists contain the culprit. They plan to make a phone call tonight to see if they can combine their information to find the culprit. However, the locals (who know the 8 suspects, but neither of the narrowed lists) have tapped their phone line. If the locals can figure out the culprit based on this phone call, then they will lynch him before he can be brought to justice.
How can the sheriffs conduct their conversation so that they can both deduce the culprit, when possible\*, but the locals can't?
\*If the sheriffs have the same list of 2 suspects, then they won't be able to deduce the culprit. As long as their lists are different, they can. The lists cannot be disjoint, since they both contain the unique culprit.
Source: *Mathematical Puzzles, a Connoisseur's Collection*, Peter Winkler | 2015/03/30 | [
"https://puzzling.stackexchange.com/questions/11267",
"https://puzzling.stackexchange.com",
"https://puzzling.stackexchange.com/users/10615/"
] | In actual conversation:
Suspects: 1 2 3 4 5 6 7 8
Sheriff A has 1 2
Sheriff B has 1 5
(Phone rings.)
A: Bad news, someone tapped me.
B: OK. Group suspects into 4 pairs with one pair being your shortlist
A: 12 34 56 78
B: Is it either 12 or 34?
A: Yes
B: (so culprit is 1) culprit is either 1 or 3
A: (so culprit is 1) let's go get him
(Both hang up the phone) | >
> they number the suspects in binary, then each officer tells the other which digit he needs to incriminate the right suspect. the other officer can either give him that digit right away if he has it, or request a digit himself.
>
>
>
example
officer A has
011
101
officer B has
000
011
officer A needs either the first or second digit.
officer B needs either the second or third digit.
officer A tells B the third digit it 1.
officer B tells A the first digit is 0. |
11,267 | Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, they can be sure that both of their lists contain the culprit. They plan to make a phone call tonight to see if they can combine their information to find the culprit. However, the locals (who know the 8 suspects, but neither of the narrowed lists) have tapped their phone line. If the locals can figure out the culprit based on this phone call, then they will lynch him before he can be brought to justice.
How can the sheriffs conduct their conversation so that they can both deduce the culprit, when possible\*, but the locals can't?
\*If the sheriffs have the same list of 2 suspects, then they won't be able to deduce the culprit. As long as their lists are different, they can. The lists cannot be disjoint, since they both contain the unique culprit.
Source: *Mathematical Puzzles, a Connoisseur's Collection*, Peter Winkler | 2015/03/30 | [
"https://puzzling.stackexchange.com/questions/11267",
"https://puzzling.stackexchange.com",
"https://puzzling.stackexchange.com/users/10615/"
] | I think it's pretty obvious.
>
> They discuss a meeting place on the phone and then talk about it in person.
>
>
>
;)
---
Alternatively,
>
> one sheriff reads his two suspects' names. The other sheriff says nothing and goes to arrest the culprit.
>
>
> | I'm finding one small issue with mine (in the worst case scenario), so hopefully this will help someone else.
>
> One sheriff reads names **NOT** on his list ("I know it isn't \_\_\_\_) until he reads a name on the second sheriff's list. We know the first sheriff will have to say some name he knows it isn't that the second sheriff thinks it is, or the case is unsolvable.
>
>
> The second Sheriff now knows the culprit. The second sheriff can now begin the same process ("I know it isn't \_\_\_\_") until he reads a name on the first sheriff's list. He needs to stop before the final name though if he gets that far, or he could still reveal who the culprit is (if the two sheriff's have together said it isn't 7 of the 8).
>
>
>
I realize this isn't fullproof, given the situation of:
>
> If luck is really bad and the second sheriff reads the entire list and the two remaining names (the culprit, and last person unsaid to avoid giving too much away) are both suspects to the first sheriff. Then this way wouldn't work.
>
>
> |
11,267 | Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, they can be sure that both of their lists contain the culprit. They plan to make a phone call tonight to see if they can combine their information to find the culprit. However, the locals (who know the 8 suspects, but neither of the narrowed lists) have tapped their phone line. If the locals can figure out the culprit based on this phone call, then they will lynch him before he can be brought to justice.
How can the sheriffs conduct their conversation so that they can both deduce the culprit, when possible\*, but the locals can't?
\*If the sheriffs have the same list of 2 suspects, then they won't be able to deduce the culprit. As long as their lists are different, they can. The lists cannot be disjoint, since they both contain the unique culprit.
Source: *Mathematical Puzzles, a Connoisseur's Collection*, Peter Winkler | 2015/03/30 | [
"https://puzzling.stackexchange.com/questions/11267",
"https://puzzling.stackexchange.com",
"https://puzzling.stackexchange.com/users/10615/"
] | Let's say S1 has the list {a,b} and say S2 has {a,c}.
S1: {a,b}, {c,d}, {e,f}, {g,h} - one of these is my list.
S2: {a,c}, {b,d}, {e,g}, {f,h} - one of these is mine.
Now both S1,S2 know their sets are inside {a,b,c,d}, whereas because of symmetry,
it could be {e,f,g,h} or {a,b,c,d} as far as eavesdroppers are concerned.
So S1 and S2 play a game revealing info but keeping this info symmetric in the other set too.
S1: {a,e}, {b,f} - These lists have my suspects.
S2: Knows the culprit is a (since he knows S1's set now).
S2: {a,e} - The culprit is in this list.
S1: Knows the culprit is a.
Each time, the eavesdroppers can't distinguish between the two sets;
finally they can't distinguish between a and e. | The crude answer to this is that they manually perform a [Diffie-Hellman key exchange](http://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange) over the phone.
Then they can just encrypt their lists with [AES](http://en.wikipedia.org/wiki/Advanced_Encryption_Standard) with the key, and speak it.
Surely this isn't the most efficient or effective way, but encryption is the catch-all when it comes to questions of communicating secrets in the open :) |
11,267 | Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, they can be sure that both of their lists contain the culprit. They plan to make a phone call tonight to see if they can combine their information to find the culprit. However, the locals (who know the 8 suspects, but neither of the narrowed lists) have tapped their phone line. If the locals can figure out the culprit based on this phone call, then they will lynch him before he can be brought to justice.
How can the sheriffs conduct their conversation so that they can both deduce the culprit, when possible\*, but the locals can't?
\*If the sheriffs have the same list of 2 suspects, then they won't be able to deduce the culprit. As long as their lists are different, they can. The lists cannot be disjoint, since they both contain the unique culprit.
Source: *Mathematical Puzzles, a Connoisseur's Collection*, Peter Winkler | 2015/03/30 | [
"https://puzzling.stackexchange.com/questions/11267",
"https://puzzling.stackexchange.com",
"https://puzzling.stackexchange.com/users/10615/"
] | I think it's pretty obvious.
>
> They discuss a meeting place on the phone and then talk about it in person.
>
>
>
;)
---
Alternatively,
>
> one sheriff reads his two suspects' names. The other sheriff says nothing and goes to arrest the culprit.
>
>
> | The crude answer to this is that they manually perform a [Diffie-Hellman key exchange](http://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange) over the phone.
Then they can just encrypt their lists with [AES](http://en.wikipedia.org/wiki/Advanced_Encryption_Standard) with the key, and speak it.
Surely this isn't the most efficient or effective way, but encryption is the catch-all when it comes to questions of communicating secrets in the open :) |
11,267 | Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, they can be sure that both of their lists contain the culprit. They plan to make a phone call tonight to see if they can combine their information to find the culprit. However, the locals (who know the 8 suspects, but neither of the narrowed lists) have tapped their phone line. If the locals can figure out the culprit based on this phone call, then they will lynch him before he can be brought to justice.
How can the sheriffs conduct their conversation so that they can both deduce the culprit, when possible\*, but the locals can't?
\*If the sheriffs have the same list of 2 suspects, then they won't be able to deduce the culprit. As long as their lists are different, they can. The lists cannot be disjoint, since they both contain the unique culprit.
Source: *Mathematical Puzzles, a Connoisseur's Collection*, Peter Winkler | 2015/03/30 | [
"https://puzzling.stackexchange.com/questions/11267",
"https://puzzling.stackexchange.com",
"https://puzzling.stackexchange.com/users/10615/"
] | I think it's pretty obvious.
>
> They discuss a meeting place on the phone and then talk about it in person.
>
>
>
;)
---
Alternatively,
>
> one sheriff reads his two suspects' names. The other sheriff says nothing and goes to arrest the culprit.
>
>
> | >
> They each encrypt their list with the other sheriff's RSA public key. They then read the encrypted string over the phone to the other, and each sheriff then decrypts the other's list using his own private key :).
>
>
>
It's going to be a long phone call.
I haven't taken computer security in a while so I hope I got the process right, I was just kinda going off the top of my head. |
11,267 | Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, they can be sure that both of their lists contain the culprit. They plan to make a phone call tonight to see if they can combine their information to find the culprit. However, the locals (who know the 8 suspects, but neither of the narrowed lists) have tapped their phone line. If the locals can figure out the culprit based on this phone call, then they will lynch him before he can be brought to justice.
How can the sheriffs conduct their conversation so that they can both deduce the culprit, when possible\*, but the locals can't?
\*If the sheriffs have the same list of 2 suspects, then they won't be able to deduce the culprit. As long as their lists are different, they can. The lists cannot be disjoint, since they both contain the unique culprit.
Source: *Mathematical Puzzles, a Connoisseur's Collection*, Peter Winkler | 2015/03/30 | [
"https://puzzling.stackexchange.com/questions/11267",
"https://puzzling.stackexchange.com",
"https://puzzling.stackexchange.com/users/10615/"
] | Let's say S1 has the list {a,b} and say S2 has {a,c}.
S1: {a,b}, {c,d}, {e,f}, {g,h} - one of these is my list.
S2: {a,c}, {b,d}, {e,g}, {f,h} - one of these is mine.
Now both S1,S2 know their sets are inside {a,b,c,d}, whereas because of symmetry,
it could be {e,f,g,h} or {a,b,c,d} as far as eavesdroppers are concerned.
So S1 and S2 play a game revealing info but keeping this info symmetric in the other set too.
S1: {a,e}, {b,f} - These lists have my suspects.
S2: Knows the culprit is a (since he knows S1's set now).
S2: {a,e} - The culprit is in this list.
S1: Knows the culprit is a.
Each time, the eavesdroppers can't distinguish between the two sets;
finally they can't distinguish between a and e. | >
> They each encrypt their list with the other sheriff's RSA public key. They then read the encrypted string over the phone to the other, and each sheriff then decrypts the other's list using his own private key :).
>
>
>
It's going to be a long phone call.
I haven't taken computer security in a while so I hope I got the process right, I was just kinda going off the top of my head. |
11,267 | Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, they can be sure that both of their lists contain the culprit. They plan to make a phone call tonight to see if they can combine their information to find the culprit. However, the locals (who know the 8 suspects, but neither of the narrowed lists) have tapped their phone line. If the locals can figure out the culprit based on this phone call, then they will lynch him before he can be brought to justice.
How can the sheriffs conduct their conversation so that they can both deduce the culprit, when possible\*, but the locals can't?
\*If the sheriffs have the same list of 2 suspects, then they won't be able to deduce the culprit. As long as their lists are different, they can. The lists cannot be disjoint, since they both contain the unique culprit.
Source: *Mathematical Puzzles, a Connoisseur's Collection*, Peter Winkler | 2015/03/30 | [
"https://puzzling.stackexchange.com/questions/11267",
"https://puzzling.stackexchange.com",
"https://puzzling.stackexchange.com/users/10615/"
] | In actual conversation:
Suspects: 1 2 3 4 5 6 7 8
Sheriff A has 1 2
Sheriff B has 1 5
(Phone rings.)
A: Bad news, someone tapped me.
B: OK. Group suspects into 4 pairs with one pair being your shortlist
A: 12 34 56 78
B: Is it either 12 or 34?
A: Yes
B: (so culprit is 1) culprit is either 1 or 3
A: (so culprit is 1) let's go get him
(Both hang up the phone) | The crude answer to this is that they manually perform a [Diffie-Hellman key exchange](http://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange) over the phone.
Then they can just encrypt their lists with [AES](http://en.wikipedia.org/wiki/Advanced_Encryption_Standard) with the key, and speak it.
Surely this isn't the most efficient or effective way, but encryption is the catch-all when it comes to questions of communicating secrets in the open :) |
177,391 | In normal job-hunting, it's acceptable to apply for jobs "informationally", to learn about new opportunities before deciding whether the new opportunity is better than your current.
Suppose I'm a published MS-level researcher in industry, but have gotten interested in certain research projects in academia and see PhD student lab openings. I'd like to learn more about the projects to see if the project direction is a good fit for my interests, see if I like the culture of the team, see if I like the location, learn more about the funding situation and expected work-life balance of the lab. All five of these things are unknowns when applying to a normal job, and it's acceptable in industry (I'm in EECS) to interview for several rounds with on-site visits to find answers on both sides before deciding if it's a good fit. If for any reason the applicant declines, it's perfectly acceptable to interview with the same team a few years down the road as projects, willingness to relocate, family situation all change dramatically over the course of one's lifetime.
As a practicing researcher in the field, I can of course do due diligence and read the relevant papers/ codebases, etc., but interviewing with the faculty and meeting the future team by being accepted to the associated graduate program are necessary to fully evaluate whether the new position is more desirable than the current one.
Would this attitude be seen negatively, both by the potential future advising faculty or the larger admitting institution? Would schools be more reluctant to admit me if I re-apply? For context, I'm in the US and would be applying to top-N schools.
If this approach is not appropriate for grad-school, how would I go about managing how project/location/team/cultural fit, from my perspective, could change over my lifetime as, e.g., the kids grow up and move out, the field changes and develops. It seems a bit absurd that, because an opportunity or team was not a good fit at some point in my lifetime, it would be closed to me for the rest of a 30 year career, so if this is the case I have trouble understanding the underlying reasoning. | 2021/10/31 | [
"https://academia.stackexchange.com/questions/177391",
"https://academia.stackexchange.com",
"https://academia.stackexchange.com/users/129176/"
] | In my view, it's completely different to apply intending to find a position but not find the right fit than it is to apply "explorationally" to gather information without intending to follow through during the current admissions cycle. And I don't think that's unique to grad school/academia, it's rude to waste any interviewer's time.
In industry, it's more common to be contacted for an interview or to go into an interview where both parties know you aren't on the immediate job market. That's different from abusing someone else's time for practice or whatever else. Yes, you'll find professional articles written that say otherwise. Sure, you might see other people doing it. Rude people do rude things all the time, selfish people coach others to be selfish; that doesn't make them less rude or selfish.
Applying isn't a commitment to take a position, and it would be wrong for someone to take your honest rejection of their offer too personally. However, they have every right next time around to be skeptical of your interest. Offers for grad school positions usually come on a fairly competitive calendar; if someone doesn't accept your offer, their second choice might have already committed elsewhere.
It seems you aren't quite sure if you want to go the academic route. I'd recommend reaching out to labs to communicate without applying. Let them know, honestly, what your position is. You probably have resources to travel, so visit some potential cities as a tourist and see how you like the vibe on your own. If you're doing research work now that's of academic interest, you may be able to arrange to visit and give a talk like an academic would, which typically comes with opportunities to meet with faculty and current students (and maybe even a honorarium for speaking, or at least a free meal).
And know that you aren't that special for having started an industry career first - most people have. A PhD in the US is usually a 5+ year commitment, and it's coming with a likely big pay cut for you. Rather than having negotiating power due to your salary and experience, you are probably in a negotiating hole because you are a higher risk to drop out after experiencing a cost of living crunch than a fresh student who has always lived in shared student housing. You'll be needing to explain why exactly you're a good fit for academia, and you'll have to convince programs that you're committed to them. | For better or worse, there are some major differences between applying to PhD programs and applying for industry jobs, that mean that treating an application for a PhD spot like an application for a job probably won't work.
For one thing, in the US normally you are applying to a graduate program, rather than a specific lab. While it helps a lot to have a clear idea of what groups you want to work for, being admitted to a graduate program is not a guarantee that you will be able to work with a specific group.
For another thing, you are applying for an educational program, not a job. The goal is not just for you to produce, but to learn. This has a lot of implications, but relevant to your question, if you apply, receive an offer, and reject the offer to stay in your current job, there can be a perception that you are not serious about pursuing further education, which can color how your application will be viewed (should you apply again).
Finally, the laws of supply and demand are not on your side. There are more graduating BS and MS students every year looking for PhD slots, then there are PhD slots. Furthermore, while there are people who leave to go to industry and return, the "typical" path is to go to a PhD shortly after finishing a BS or MS degree. So if you apply, receive an offer, and then reject the offer, there is not an incentive to offer you another spot.
Therefore, I think that if you want to avoid potentially burning bridges, you should only apply if you think you want to go to school instead of remaining in industry.
In terms of power dynamics: fundamentally there is a power imbalance when you get a PhD, in a way there probably isn't in a typical industry job, because *you* are the one seeking a PhD. You will need to commit to one group for at least 3-5 years to make enough progress to get the PhD. It's very hard for you as a student to change groups, and if you do this will only set back your own timeline. Therefore, unlike in industry, the (implicit or explicit) threat that you could leave to go somewhere else, does not carry as much weight for PhD students in academia. Any PI will have certain resources available based on funding, there is a standard package you will get as a student, so you can't really bargain with your current salary. The bargaining chips that carry weight, are things that give you ability to produce high-impact research and win grants. But, if you are applying as a PhD student, you probably don't have already those things; you may have the *promise* to learn enough to do such things, but a typical PhD student is in the role of an apprentice being groomed.
As practical advice, I think you should use your academic network. Talk to the professors whose groups you work with about what it is like to do a PhD with them. Ask to talk to their PhD students. Maybe you could try to arrange spending a month in their lab, like an internship (of course I don't know how this would work with your company). Maybe the PIs can provide contacts for groups at institutions where you want to get a degree. I think you can learn a lot from talking to these groups before you apply about what to expect.
**IMPORTANT CAVEAT** This advice about your academic network is assuming that you feel comfortable reaching out to your academic collaborators *without* jeopardizing your current role. This may not be a safe thing to do, particularly if you are a junior person on your team, since (a) the faculty may tell your boss that you are thinking of leaving your job, and (b) there could be agreements between your collaborators and your employer that they are not supposed to "poach" current employees. I can't judge how likely (a) and (b) are in your case. There are usually agreements like (b) if two companies work together, but I don't know if that is true for academic collaboration. If you don't feel safe directly talking to people you work with about this, then you can find a lot of general advice about what a PhD is like online, including on this site, for example [Advice for thinking about whether to pursue a PhD](https://academia.stackexchange.com/questions/147306/advice-for-thinking-about-whether-to-pursue-a-phd/147347)
Philosophically, I think that if you really want to do a PhD, you can't look at it as a normal job. You have to look at it as fulfilling your passion for a subject by pursuing it deeply at the highest level. This often means making sacrifices in terms of pay, work-life balance. That's not to say there aren't ways to manage a healthy work-life balance as a PhD student, but it's not a job where you can expect to work 9-5 and get everything done. To be successful, rather than negotiating power dynamics between you and your PI, you should focus more on finding a group that will intellectually match your interests and on learning how to be a successful researcher. Now... I am not passing a value judgment on whether these attitudes are a good or bad thing. I am just saying that this is the prevailing culture in academia, which you should be aware of before deciding to purse a PhD. |
177,391 | In normal job-hunting, it's acceptable to apply for jobs "informationally", to learn about new opportunities before deciding whether the new opportunity is better than your current.
Suppose I'm a published MS-level researcher in industry, but have gotten interested in certain research projects in academia and see PhD student lab openings. I'd like to learn more about the projects to see if the project direction is a good fit for my interests, see if I like the culture of the team, see if I like the location, learn more about the funding situation and expected work-life balance of the lab. All five of these things are unknowns when applying to a normal job, and it's acceptable in industry (I'm in EECS) to interview for several rounds with on-site visits to find answers on both sides before deciding if it's a good fit. If for any reason the applicant declines, it's perfectly acceptable to interview with the same team a few years down the road as projects, willingness to relocate, family situation all change dramatically over the course of one's lifetime.
As a practicing researcher in the field, I can of course do due diligence and read the relevant papers/ codebases, etc., but interviewing with the faculty and meeting the future team by being accepted to the associated graduate program are necessary to fully evaluate whether the new position is more desirable than the current one.
Would this attitude be seen negatively, both by the potential future advising faculty or the larger admitting institution? Would schools be more reluctant to admit me if I re-apply? For context, I'm in the US and would be applying to top-N schools.
If this approach is not appropriate for grad-school, how would I go about managing how project/location/team/cultural fit, from my perspective, could change over my lifetime as, e.g., the kids grow up and move out, the field changes and develops. It seems a bit absurd that, because an opportunity or team was not a good fit at some point in my lifetime, it would be closed to me for the rest of a 30 year career, so if this is the case I have trouble understanding the underlying reasoning. | 2021/10/31 | [
"https://academia.stackexchange.com/questions/177391",
"https://academia.stackexchange.com",
"https://academia.stackexchange.com/users/129176/"
] | In my view, it's completely different to apply intending to find a position but not find the right fit than it is to apply "explorationally" to gather information without intending to follow through during the current admissions cycle. And I don't think that's unique to grad school/academia, it's rude to waste any interviewer's time.
In industry, it's more common to be contacted for an interview or to go into an interview where both parties know you aren't on the immediate job market. That's different from abusing someone else's time for practice or whatever else. Yes, you'll find professional articles written that say otherwise. Sure, you might see other people doing it. Rude people do rude things all the time, selfish people coach others to be selfish; that doesn't make them less rude or selfish.
Applying isn't a commitment to take a position, and it would be wrong for someone to take your honest rejection of their offer too personally. However, they have every right next time around to be skeptical of your interest. Offers for grad school positions usually come on a fairly competitive calendar; if someone doesn't accept your offer, their second choice might have already committed elsewhere.
It seems you aren't quite sure if you want to go the academic route. I'd recommend reaching out to labs to communicate without applying. Let them know, honestly, what your position is. You probably have resources to travel, so visit some potential cities as a tourist and see how you like the vibe on your own. If you're doing research work now that's of academic interest, you may be able to arrange to visit and give a talk like an academic would, which typically comes with opportunities to meet with faculty and current students (and maybe even a honorarium for speaking, or at least a free meal).
And know that you aren't that special for having started an industry career first - most people have. A PhD in the US is usually a 5+ year commitment, and it's coming with a likely big pay cut for you. Rather than having negotiating power due to your salary and experience, you are probably in a negotiating hole because you are a higher risk to drop out after experiencing a cost of living crunch than a fresh student who has always lived in shared student housing. You'll be needing to explain why exactly you're a good fit for academia, and you'll have to convince programs that you're committed to them. | PhD programs will happily continue accepting your application fees. It is your life and your money. If you were not serious about doing PhD study, then the money budgeted to such fees could be better spent on such things as a vacation, dinner at a fancy restaurant, etc.
If you really have nothing better to spend your money on, you could give it to me. I will without complaint relieve you of any surplus money that is holding you back from achieving your dreams. |
177,391 | In normal job-hunting, it's acceptable to apply for jobs "informationally", to learn about new opportunities before deciding whether the new opportunity is better than your current.
Suppose I'm a published MS-level researcher in industry, but have gotten interested in certain research projects in academia and see PhD student lab openings. I'd like to learn more about the projects to see if the project direction is a good fit for my interests, see if I like the culture of the team, see if I like the location, learn more about the funding situation and expected work-life balance of the lab. All five of these things are unknowns when applying to a normal job, and it's acceptable in industry (I'm in EECS) to interview for several rounds with on-site visits to find answers on both sides before deciding if it's a good fit. If for any reason the applicant declines, it's perfectly acceptable to interview with the same team a few years down the road as projects, willingness to relocate, family situation all change dramatically over the course of one's lifetime.
As a practicing researcher in the field, I can of course do due diligence and read the relevant papers/ codebases, etc., but interviewing with the faculty and meeting the future team by being accepted to the associated graduate program are necessary to fully evaluate whether the new position is more desirable than the current one.
Would this attitude be seen negatively, both by the potential future advising faculty or the larger admitting institution? Would schools be more reluctant to admit me if I re-apply? For context, I'm in the US and would be applying to top-N schools.
If this approach is not appropriate for grad-school, how would I go about managing how project/location/team/cultural fit, from my perspective, could change over my lifetime as, e.g., the kids grow up and move out, the field changes and develops. It seems a bit absurd that, because an opportunity or team was not a good fit at some point in my lifetime, it would be closed to me for the rest of a 30 year career, so if this is the case I have trouble understanding the underlying reasoning. | 2021/10/31 | [
"https://academia.stackexchange.com/questions/177391",
"https://academia.stackexchange.com",
"https://academia.stackexchange.com/users/129176/"
] | For better or worse, there are some major differences between applying to PhD programs and applying for industry jobs, that mean that treating an application for a PhD spot like an application for a job probably won't work.
For one thing, in the US normally you are applying to a graduate program, rather than a specific lab. While it helps a lot to have a clear idea of what groups you want to work for, being admitted to a graduate program is not a guarantee that you will be able to work with a specific group.
For another thing, you are applying for an educational program, not a job. The goal is not just for you to produce, but to learn. This has a lot of implications, but relevant to your question, if you apply, receive an offer, and reject the offer to stay in your current job, there can be a perception that you are not serious about pursuing further education, which can color how your application will be viewed (should you apply again).
Finally, the laws of supply and demand are not on your side. There are more graduating BS and MS students every year looking for PhD slots, then there are PhD slots. Furthermore, while there are people who leave to go to industry and return, the "typical" path is to go to a PhD shortly after finishing a BS or MS degree. So if you apply, receive an offer, and then reject the offer, there is not an incentive to offer you another spot.
Therefore, I think that if you want to avoid potentially burning bridges, you should only apply if you think you want to go to school instead of remaining in industry.
In terms of power dynamics: fundamentally there is a power imbalance when you get a PhD, in a way there probably isn't in a typical industry job, because *you* are the one seeking a PhD. You will need to commit to one group for at least 3-5 years to make enough progress to get the PhD. It's very hard for you as a student to change groups, and if you do this will only set back your own timeline. Therefore, unlike in industry, the (implicit or explicit) threat that you could leave to go somewhere else, does not carry as much weight for PhD students in academia. Any PI will have certain resources available based on funding, there is a standard package you will get as a student, so you can't really bargain with your current salary. The bargaining chips that carry weight, are things that give you ability to produce high-impact research and win grants. But, if you are applying as a PhD student, you probably don't have already those things; you may have the *promise* to learn enough to do such things, but a typical PhD student is in the role of an apprentice being groomed.
As practical advice, I think you should use your academic network. Talk to the professors whose groups you work with about what it is like to do a PhD with them. Ask to talk to their PhD students. Maybe you could try to arrange spending a month in their lab, like an internship (of course I don't know how this would work with your company). Maybe the PIs can provide contacts for groups at institutions where you want to get a degree. I think you can learn a lot from talking to these groups before you apply about what to expect.
**IMPORTANT CAVEAT** This advice about your academic network is assuming that you feel comfortable reaching out to your academic collaborators *without* jeopardizing your current role. This may not be a safe thing to do, particularly if you are a junior person on your team, since (a) the faculty may tell your boss that you are thinking of leaving your job, and (b) there could be agreements between your collaborators and your employer that they are not supposed to "poach" current employees. I can't judge how likely (a) and (b) are in your case. There are usually agreements like (b) if two companies work together, but I don't know if that is true for academic collaboration. If you don't feel safe directly talking to people you work with about this, then you can find a lot of general advice about what a PhD is like online, including on this site, for example [Advice for thinking about whether to pursue a PhD](https://academia.stackexchange.com/questions/147306/advice-for-thinking-about-whether-to-pursue-a-phd/147347)
Philosophically, I think that if you really want to do a PhD, you can't look at it as a normal job. You have to look at it as fulfilling your passion for a subject by pursuing it deeply at the highest level. This often means making sacrifices in terms of pay, work-life balance. That's not to say there aren't ways to manage a healthy work-life balance as a PhD student, but it's not a job where you can expect to work 9-5 and get everything done. To be successful, rather than negotiating power dynamics between you and your PI, you should focus more on finding a group that will intellectually match your interests and on learning how to be a successful researcher. Now... I am not passing a value judgment on whether these attitudes are a good or bad thing. I am just saying that this is the prevailing culture in academia, which you should be aware of before deciding to purse a PhD. | PhD programs will happily continue accepting your application fees. It is your life and your money. If you were not serious about doing PhD study, then the money budgeted to such fees could be better spent on such things as a vacation, dinner at a fancy restaurant, etc.
If you really have nothing better to spend your money on, you could give it to me. I will without complaint relieve you of any surplus money that is holding you back from achieving your dreams. |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | Icsn (and Ics-ssl) components at :
<http://www.overbyte.be/frame_index.html> | SMTP is so trivial protocol (unless you use SASL or other exotic authentication methods) that any component would work. Of course, I would recommend our [SecureBlackbox](http://www.eldos.com/sbb/) product. Freeware libraries such as Indy, ICS, Synapse to get SSL have bindings to OpenSSL DLL and also to SecureBlackbox (none of the listed has own SSL implementation). |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | Icsn (and Ics-ssl) components at :
<http://www.overbyte.be/frame_index.html> | I've used IP\*Works SMTP component before. I didn't do anything involved with them, I used them to send an email with error information basically. I have never used the SSL version either.
I don't believe you can purchase the components individually either.
<http://nsoftware.com/ipworks/components.aspx> |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | Icsn (and Ics-ssl) components at :
<http://www.overbyte.be/frame_index.html> | I use [Synapse](http://synapse.ararat.cz/doku.php) library. It works very well with SSL/TLS. There is public wiki with information on "[How To Use SMTP with TLS](http://synapse.ararat.cz/doku.php/public:howto:smtpsend)". It works with Delphi (I use Turbo that is based on 2006) and FPC. It is "normal" library, not component and in my opinion this is advantage for command line utilities or server applications. |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | I've used IP\*Works SMTP component before. I didn't do anything involved with them, I used them to send an email with error information basically. I have never used the SSL version either.
I don't believe you can purchase the components individually either.
<http://nsoftware.com/ipworks/components.aspx> | SMTP is so trivial protocol (unless you use SASL or other exotic authentication methods) that any component would work. Of course, I would recommend our [SecureBlackbox](http://www.eldos.com/sbb/) product. Freeware libraries such as Indy, ICS, Synapse to get SSL have bindings to OpenSSL DLL and also to SecureBlackbox (none of the listed has own SSL implementation). |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | Indy 10's SMTP component supports SSL. What problems are you having with it? | SMTP is so trivial protocol (unless you use SASL or other exotic authentication methods) that any component would work. Of course, I would recommend our [SecureBlackbox](http://www.eldos.com/sbb/) product. Freeware libraries such as Indy, ICS, Synapse to get SSL have bindings to OpenSSL DLL and also to SecureBlackbox (none of the listed has own SSL implementation). |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | I use [Synapse](http://synapse.ararat.cz/doku.php) library. It works very well with SSL/TLS. There is public wiki with information on "[How To Use SMTP with TLS](http://synapse.ararat.cz/doku.php/public:howto:smtpsend)". It works with Delphi (I use Turbo that is based on 2006) and FPC. It is "normal" library, not component and in my opinion this is advantage for command line utilities or server applications. | SMTP is so trivial protocol (unless you use SASL or other exotic authentication methods) that any component would work. Of course, I would recommend our [SecureBlackbox](http://www.eldos.com/sbb/) product. Freeware libraries such as Indy, ICS, Synapse to get SSL have bindings to OpenSSL DLL and also to SecureBlackbox (none of the listed has own SSL implementation). |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | Indy 10's SMTP component supports SSL. What problems are you having with it? | I've used IP\*Works SMTP component before. I didn't do anything involved with them, I used them to send an email with error information basically. I have never used the SSL version either.
I don't believe you can purchase the components individually either.
<http://nsoftware.com/ipworks/components.aspx> |
3,761,614 | Indy is not enough for me, it must support SSL and be rock solid, can be commercial also | 2010/09/21 | [
"https://Stackoverflow.com/questions/3761614",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/454095/"
] | Indy 10's SMTP component supports SSL. What problems are you having with it? | I use [Synapse](http://synapse.ararat.cz/doku.php) library. It works very well with SSL/TLS. There is public wiki with information on "[How To Use SMTP with TLS](http://synapse.ararat.cz/doku.php/public:howto:smtpsend)". It works with Delphi (I use Turbo that is based on 2006) and FPC. It is "normal" library, not component and in my opinion this is advantage for command line utilities or server applications. |
38,251 | Within our team we would like to do load tests in a CI process. For this we want to use either Jmeter or just a comparable tool.
Jmeter offers u.a. the possibility that one can plan and execute a test pipeline for a load test via plugin.
The question we ask ourselves, how often should we perform this load test but in the development accordingly?
How often do you use your load test in your planning? Weekly? Several times a week?
Project details:
Webpages
Java, Javascript, Angular | 2019/03/13 | [
"https://sqa.stackexchange.com/questions/38251",
"https://sqa.stackexchange.com",
"https://sqa.stackexchange.com/users/37123/"
] | IMO, for every major code change, you need to execute load test. You can decide either you can execute a load test as part of sprint closing/feature closing. | Make the load testing part of your performance suite so it runs automatically when you push branch commits to your CI system and fails when user experience deteriorates. The level at which that happens, e.g. slow slow responses is something you will need to define.
I also recommend you consider creating functional tests and then making them part of your performance suite so that you are stimulating actual user usage patterns. For example a selenium suite that fills forms.
jMeter is the clear leader in the field but it is an old clunky tool. Consider rolling your own, for example with Ruby which gives you thread management and the Benchmark library |
56,768 | Let's say I wrote the following in an essay.
>
> Hello, Anna. I love you
>
>
>
Now I want to write something like this: This line I've written was supposedly said by Anna's boyfriend, but Anna's boyfriend didn't actually say it himself. It's a creative work of mine pretending to be Anna's boyfriend.
Note that this question is tagged with "sentence-construction" because I also want to know how I could state this in one neat sentence. | 2015/05/14 | [
"https://ell.stackexchange.com/questions/56768",
"https://ell.stackexchange.com",
"https://ell.stackexchange.com/users/19552/"
] | You simply need to change "*by* himself" to "himself" or even leave himself out entirely.
**But Anna's boyfriend didn't say it himself. I said it, pretending to be him.
But Anna's boyfriend didn't say it. I said it, pretending to be him.**
*did not say this by himself* means that *someone helped him* to say this.
*did not say this himself* means that *he* did not say this. | * I imagine he said, "Anna, ... I love you".
* If I were in his shoes, I would come-right-out and say, "Anna, ... I love you".
* "Anna, ... I love you", would have been the right thing for him to have said.
* He should have said, "Anna, ... I love you", but he didn't.
* If, for example, he had said, "Anna, ... I love you", they would be together today but he missed his opportunity.
These are all examples of how you could refer to another person's motives or actions. Your choice of "voice" would depend on the nuance that you want to convey. |
14,740 | I'm trying to plan the pieces I'll need for a castle door.
I know I need 2 of [these doors](https://www.bricklink.com/v2/catalog/catalogitem.page?P=2554&idColor=11#T=C&C=11).
Based on the part list for [Adventurers Tomb set](https://www.bricklink.com/v2/catalog/catalogitem.page?S=2996-1#T=S&O=%7B%22st%22:%224%22,%22ss%22:%22US%22,%22rpp%22:%22100%22,%22iconly%22:0%7D), it looks like I'll need several [shutter holders](https://www.bricklink.com/v2/catalog/catalogitem.page?P=3581&idColor=9#T=C&C=9), right? Is there a way to fill in the curves around the top so the front is solid? | 2020/05/11 | [
"https://bricks.stackexchange.com/questions/14740",
"https://bricks.stackexchange.com",
"https://bricks.stackexchange.com/users/13805/"
] | The [Adventures Tomb 2996](https://brickset.com/sets/2996-1/Adventurers-Tomb) set you mentioned uses [shutter holders](https://rebrickable.com/parts/3581/brick-special-1-x-1-x-2-with-shutter-holder/) to mount the door and a [1x6x1 arch](https://rebrickable.com/parts/3455/brick-arch-1-x-6/) to cover the space behind the doors:
[](https://i.stack.imgur.com/dUlVj.png)
[](https://i.stack.imgur.com/pMgLl.png)
It is also very common to use a [1x6x2 arch](https://rebrickable.com/parts/3307/brick-arch-1-x-6-x-2-thick-top-with-reinforced-underside/), as was done in [Dark Fortress Landing 8802](https://brickset.com/sets/8802-1/Dark-Fortress-Landing):
[](https://i.stack.imgur.com/aZCrt.jpg)
As I mentioned in [another answer](https://bricks.stackexchange.com/questions/6265/how-do-you-eliminate-the-gap-between-castle-doors), these clips generally attach to the back of the door, not the side. The geometry is more complicated to completely fill if you want to have the doors hinge from the side. | I have those doors, and you're right about the shutter holder bricks, which are pretty fragile. The doors each cover half the space under a 1x6x2 arch. Besides the shutter snaps, the only connection point is the stud/doorknob. |
466,553 | How do the diodes protect the input of amplifier from excess voltage in the circuit below?
[](https://i.stack.imgur.com/fO89q.jpg) | 2019/11/09 | [
"https://electronics.stackexchange.com/questions/466553",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/207122/"
] | 1N4148 diodes are made of silicon and conduct very little until the forward voltage reaches 0.6 V or so.
* On positive half-cycles D1 will remain "open-circuit" unless the audio signal exceeds 0.5 to 0.6 V. If the signal exceeds the forward voltage of the diode then the signal will be clamped at the forward voltage. You will hear distortion.
* On positive half-cycles D2 is reverse biased so it won't conduct.
* On negative half-cycles the situation is reversed. | The 1N4158 will have this behavior (assuming N=1 for doping profile, and 1mA at 0.6 volts)
10mA @ 0.658 volt; incremental R = 2.6 ohms
1mA @0.600 volt; incremental R = 26 ohms
0.1mA @0.542 volt; incremental R = 260 ohms
0.01mA @0.484 volt incremental R = 2,600 ohms
0.001mA @0.426 volt; incremental R = 26,000 ohms
0.0001mA @0.368 volt; incremental R = 260,000 ohms
What does this table tell us?
Consider the 0.0001mA line; for the 1N4148 to conduct that current, the potentiometer
wiper must output 0.368 volts, at which point the diode has an incremental resistance (we can this the small\_signal model) of 260,000.
You can compute the worst case effect, at 0.0001mA, by improving the model with a 260Kohm resistor from potentiometer wiper to Ground.
Given your pot is 10Kohm,the worst case effect (assuming the Rsource into the 1uF is zero ohms, is with wiper set to the middle, whereupon you can model the pot at 5K || 5K or 2.5K.
The diode's incremental R of 260,000 ohms forms a voltage divider with the pot at 2.5Kohm.
This voltage divider will add about 1% distortion: none at the zero crossings of a sin, and maximum (1%) at the + and - peak of the sin.
By the way, notice the diode voltage is the scaled logarithm of the diode current. This behavior continues down to nanoAmp and picoAmp current levels.
**THERE IS NO ABRUPT THRESHOLD FOR DIODE CURRENT** |
3,588 | Is there a source with records of the participants and/or casualties of the Russian army during the WWI period (1914-1918) and thereabouts? Preferably on-line and indexed/searchable by name(s), birthplace, place of residence and whatever else data the authorities gathered for the recruits. | 2013/07/22 | [
"https://genealogy.stackexchange.com/questions/3588",
"https://genealogy.stackexchange.com",
"https://genealogy.stackexchange.com/users/776/"
] | There are some sources but they are fragmented and most of them are not digitized yet.
One online source about WWI casualties for 1914-1915 years is in the [Russian State Library](http://sigla.rsl.ru/table.jsp?f=1016&t=3&v0=%D0%98%D0%BC%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9%20%D1%81%D0%BF%D0%B8%D1%81%D0%BE%D0%BA%20%D1%83%D0%B1%D0%B8%D1%82%D1%8B%D0%BC,%20%D1%80%D0%B0%D0%BD%D0%B5%D0%BD%D1%8B%D0%BC%20%D0%B8%20%D0%B1%D0%B5%D0%B7%20%D0%B2%D0%B5%D1%81%D1%82%D0%B8%20%D0%BF%D1%80%D0%BE%D0%BF%D0%B0%D0%B2%D1%88%D0%B8%D0%BC&f=1003&t=1&v1=&f=4&t=2&v2=&x=28&y=12&f=21&t=3&v3=&f=1016&t=3&v4=&f=1016&t=3&v5=&bf=4&b=&d=0&ys=&ye=&lng=&ft=&mt=&doi=&dt=&vol=&pt=&iss=&ps=&pe=&tr=Cyr-Common&tro=&cc=b3&i=1&v=tagged&s=2&ss=0&st=0&i18n=ru&psz=20&bs=20). It's far from being complete, but it's the largest online source I know of.
I don't think there are any indexed/searchable sources at all. | There is a Russian website that has a project going to provide the data within pdf format spreadsheets. These are also in Russian and provided according to Russian province. You can find these records at <http://svrt.ru/1914/1914-1.htm> . |
3,588 | Is there a source with records of the participants and/or casualties of the Russian army during the WWI period (1914-1918) and thereabouts? Preferably on-line and indexed/searchable by name(s), birthplace, place of residence and whatever else data the authorities gathered for the recruits. | 2013/07/22 | [
"https://genealogy.stackexchange.com/questions/3588",
"https://genealogy.stackexchange.com",
"https://genealogy.stackexchange.com/users/776/"
] | There are some sources but they are fragmented and most of them are not digitized yet.
One online source about WWI casualties for 1914-1915 years is in the [Russian State Library](http://sigla.rsl.ru/table.jsp?f=1016&t=3&v0=%D0%98%D0%BC%D0%B5%D0%BD%D0%BD%D0%BE%D0%B9%20%D1%81%D0%BF%D0%B8%D1%81%D0%BE%D0%BA%20%D1%83%D0%B1%D0%B8%D1%82%D1%8B%D0%BC,%20%D1%80%D0%B0%D0%BD%D0%B5%D0%BD%D1%8B%D0%BC%20%D0%B8%20%D0%B1%D0%B5%D0%B7%20%D0%B2%D0%B5%D1%81%D1%82%D0%B8%20%D0%BF%D1%80%D0%BE%D0%BF%D0%B0%D0%B2%D1%88%D0%B8%D0%BC&f=1003&t=1&v1=&f=4&t=2&v2=&x=28&y=12&f=21&t=3&v3=&f=1016&t=3&v4=&f=1016&t=3&v5=&bf=4&b=&d=0&ys=&ye=&lng=&ft=&mt=&doi=&dt=&vol=&pt=&iss=&ps=&pe=&tr=Cyr-Common&tro=&cc=b3&i=1&v=tagged&s=2&ss=0&st=0&i18n=ru&psz=20&bs=20). It's far from being complete, but it's the largest online source I know of.
I don't think there are any indexed/searchable sources at all. | I've had simliar questions about those records (and those of WWII). For WWI I was directed to try <https://gwar.mil.ru/> |
3,588 | Is there a source with records of the participants and/or casualties of the Russian army during the WWI period (1914-1918) and thereabouts? Preferably on-line and indexed/searchable by name(s), birthplace, place of residence and whatever else data the authorities gathered for the recruits. | 2013/07/22 | [
"https://genealogy.stackexchange.com/questions/3588",
"https://genealogy.stackexchange.com",
"https://genealogy.stackexchange.com/users/776/"
] | There is a Russian website that has a project going to provide the data within pdf format spreadsheets. These are also in Russian and provided according to Russian province. You can find these records at <http://svrt.ru/1914/1914-1.htm> . | I've had simliar questions about those records (and those of WWII). For WWI I was directed to try <https://gwar.mil.ru/> |
181,636 | I have two layers, a line and a point layer.
I need to make a line layer which connects all the points to the nearest line feature. How can I do that?
Is there a plugin available for QGIS?
This is a very important tool which is missing in QGIS.
ArcView has this tool: ["Nearest Features"](http://www.jennessent.com/arcview/nearest_features.htm)
 | 2016/02/21 | [
"https://gis.stackexchange.com/questions/181636",
"https://gis.stackexchange.com",
"https://gis.stackexchange.com/users/45512/"
] | As an alternative, you could:
1. Use the **Convert Lines to Points** tool from:
*Processing Toolbox > SAGA > Shapes - Points > Convert Lines to Points*
(Add points over small distances. E.g. add a point every 1m if the overall line is 100m)
[](https://i.stack.imgur.com/izAtG.png)
2. Use the **Distance to nearest hub** from:
*Processing Toolbox > QGIS geoalgorithms > Vector analysis tools > Distance to nearest hub*
(Set the parameters, using the output layer of the **Convert Lines to Points** tool as the *Destination hubs layer* and setting the *Output shape type* as **Line to hub**)
[](https://i.stack.imgur.com/wWZNN.png)
3. Final result should be a line layer which connects the original points layer with the original line layer (with line-converted points):
[](https://i.stack.imgur.com/OnmFA.png)
(without line-converted points):
[](https://i.stack.imgur.com/oGifH.png)
I used QGIS 2.12.3-Lyon. | If you find the point over the line, the shortest point, with the coordinate 3D (X,Y,Z) you need an algorithm to calc the position over the shortest line. You can using this tool <https://github.com/rafaelduartenom/findpointonline>. You need postgres to execute this tool and shapefiles. |
181,636 | I have two layers, a line and a point layer.
I need to make a line layer which connects all the points to the nearest line feature. How can I do that?
Is there a plugin available for QGIS?
This is a very important tool which is missing in QGIS.
ArcView has this tool: ["Nearest Features"](http://www.jennessent.com/arcview/nearest_features.htm)
 | 2016/02/21 | [
"https://gis.stackexchange.com/questions/181636",
"https://gis.stackexchange.com",
"https://gis.stackexchange.com/users/45512/"
] | As an alternative, you could:
1. Use the **Convert Lines to Points** tool from:
*Processing Toolbox > SAGA > Shapes - Points > Convert Lines to Points*
(Add points over small distances. E.g. add a point every 1m if the overall line is 100m)
[](https://i.stack.imgur.com/izAtG.png)
2. Use the **Distance to nearest hub** from:
*Processing Toolbox > QGIS geoalgorithms > Vector analysis tools > Distance to nearest hub*
(Set the parameters, using the output layer of the **Convert Lines to Points** tool as the *Destination hubs layer* and setting the *Output shape type* as **Line to hub**)
[](https://i.stack.imgur.com/wWZNN.png)
3. Final result should be a line layer which connects the original points layer with the original line layer (with line-converted points):
[](https://i.stack.imgur.com/OnmFA.png)
(without line-converted points):
[](https://i.stack.imgur.com/oGifH.png)
I used QGIS 2.12.3-Lyon. | [The ClosestPoint](https://plugins.qgis.org/plugins/ClosestPoint/) does what you are looking for, currently limited to selected features only. You can take a look at the code and modify it for your needs |
181,636 | I have two layers, a line and a point layer.
I need to make a line layer which connects all the points to the nearest line feature. How can I do that?
Is there a plugin available for QGIS?
This is a very important tool which is missing in QGIS.
ArcView has this tool: ["Nearest Features"](http://www.jennessent.com/arcview/nearest_features.htm)
 | 2016/02/21 | [
"https://gis.stackexchange.com/questions/181636",
"https://gis.stackexchange.com",
"https://gis.stackexchange.com/users/45512/"
] | [The ClosestPoint](https://plugins.qgis.org/plugins/ClosestPoint/) does what you are looking for, currently limited to selected features only. You can take a look at the code and modify it for your needs | If you find the point over the line, the shortest point, with the coordinate 3D (X,Y,Z) you need an algorithm to calc the position over the shortest line. You can using this tool <https://github.com/rafaelduartenom/findpointonline>. You need postgres to execute this tool and shapefiles. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | I am an amateur photographer going semi-pro and even though I still only use RAW I have come across a few occasions where RAW+JPEG was needed (or at least would be a great convenience):
* **ready to email files** (like @rowland-shaw wrote) - some times you need to get your photos out there as fast as possible
* ***lite* photo files to browse through** - given that your workflow might include taking a look in your photos from a not-so-capable computer (or other device) before importing them or even during the shoot, it is faster to load a 1.2MB JPEG than a 15MB RAW file
* **timelapse** - ok, this is an overkill but when shooting timelapse I want to have a bunch of small JPEGs ready to be opened in QuickTime to check the result and then go through the RAWs
In general, **JPEGs are for fast preview** on other devices (other than your camera) while **RAWs are for editing**. | I shoot JPEG + RAW because my camera produces *really good JPEG output*. It has flexible control over tone curves, color, and contrast. I'm not usually interested in producing HDR-compressed images — in fact, I often prefer a high contrast look which reduces dynamic range. If I get the exposure and other settings right, I really don't benefit much from RAW.
If I make a mistake with white balance or am in a tricky situation, I have the RAW file to take advantage of. Most of the time, I develop that in-camera, using the built-in tools to do so, but in the cases where I'm not satisfied with that, I use RawTherapee. (My camera allows adjustment to the color of the LCD; it's not completely color profiled, but it's basically neutral, so I can trust my eye well enough.)
I know that some cameras only allow highly compressed "Basic" JPEG in combination with RAW; mine lets me save JPEGs of any quality, and in fact, I usually use ★★★, only increasing to ★★★★ when the scene needs it or when the image appears particularly special. (See [Is it worth using the Premium JPEG quality setting?](https://photo.stackexchange.com/questions/21690/pentax-k-5-is-it-worth-using-the-premium-jpeg-quality-setting))
And, in fact, in the interest of keeping my lifetime data load sane, I only keep the RAW files for those particularly special images. I know this is verging on sacrilege against the conventional wisdom, but I haven't regretted it yet. If I had *paying customers*, I'd definitely archive it all, just in case. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | **In the RAW+JPEG workflow, JPEG is what you shoot for. RAW is the safety net.**
The primary benefit or JPEG is not smaller files (that's the second), it is that **JPEGs are actually images**. Images have advantages over RAW files, already mentioned by others: quick preview, ready to email, no processing required, etc. Once the shot is taken you are done if you did things right. | Usually people do store in both formats to save their time (as they think), in case if JPEG is ok.
But I prefer to store only in RAW. All pictures without any problems (WB, expo, contrast, etc..) I convert in batch processing, in one-two clicks. The benefits are:
* I don't need to spend some time on filtering "JPEG or RAW"
* I always keep a chance to change something
* I don't spend much time to process well-shooted pictures (thankfully to batch processing)
* I save more space on my card in camera |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | My understanding is that the convention of RAW+JPEG started early in pro digital photography (like Sports Illustrated at a bowl game) when computers were slower than they are today and RAW file tools more cumbersome to use. The idea would be that Photo Editors would look through the JPEG files to find the shots they needed. They then sent the corresponding RAW files to the technicians who would convert and tone those images. It assumes a multi-person workflow.
That said, a lot of news organizations just used JPEG files -- especially when they had to transmit files on deadline over a land line modem. | I've suggested RAW+JPEG to photographers who are fairly new to digital photography and are ambivalent about switching to a raw workflow, because they don't have raw-capable tools or are worried about the effort involved. I point out that they can keep using the JPEGs like they always have, but the raw files will be there, like a digital negative, for whenever they're ready to work with them. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | I am an amateur photographer going semi-pro and even though I still only use RAW I have come across a few occasions where RAW+JPEG was needed (or at least would be a great convenience):
* **ready to email files** (like @rowland-shaw wrote) - some times you need to get your photos out there as fast as possible
* ***lite* photo files to browse through** - given that your workflow might include taking a look in your photos from a not-so-capable computer (or other device) before importing them or even during the shoot, it is faster to load a 1.2MB JPEG than a 15MB RAW file
* **timelapse** - ok, this is an overkill but when shooting timelapse I want to have a bunch of small JPEGs ready to be opened in QuickTime to check the result and then go through the RAWs
In general, **JPEGs are for fast preview** on other devices (other than your camera) while **RAWs are for editing**. | There's a couple of benefits that spring to mind, especially for portraiture work:
* Speed of generating proofs - if a client is only going to pick 5% of shots for final use, there's little point in going through and white balancing everything, and then batch processing them to JPEG for the client to peruse.
* Instant back-up - if a card starts to fail, you might lose a file, and you instantly have a second backup, albeit with different fidelity (admittedly the 1D allows you to write files to two different cards at the same time) |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | **In the RAW+JPEG workflow, JPEG is what you shoot for. RAW is the safety net.**
The primary benefit or JPEG is not smaller files (that's the second), it is that **JPEGs are actually images**. Images have advantages over RAW files, already mentioned by others: quick preview, ready to email, no processing required, etc. Once the shot is taken you are done if you did things right. | I've suggested RAW+JPEG to photographers who are fairly new to digital photography and are ambivalent about switching to a raw workflow, because they don't have raw-capable tools or are worried about the effort involved. I point out that they can keep using the JPEGs like they always have, but the raw files will be there, like a digital negative, for whenever they're ready to work with them. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | I am an amateur photographer going semi-pro and even though I still only use RAW I have come across a few occasions where RAW+JPEG was needed (or at least would be a great convenience):
* **ready to email files** (like @rowland-shaw wrote) - some times you need to get your photos out there as fast as possible
* ***lite* photo files to browse through** - given that your workflow might include taking a look in your photos from a not-so-capable computer (or other device) before importing them or even during the shoot, it is faster to load a 1.2MB JPEG than a 15MB RAW file
* **timelapse** - ok, this is an overkill but when shooting timelapse I want to have a bunch of small JPEGs ready to be opened in QuickTime to check the result and then go through the RAWs
In general, **JPEGs are for fast preview** on other devices (other than your camera) while **RAWs are for editing**. | Depending on your camera, there might be a good reason to shoot JPEG + RAW even if your workflow is RAW-only: **accurate on-camera previews**.
Some cameras work like this (IIRC, I have seen this behaviour at least on Canon PowerShot S95):
* If you shoot RAW-only, the camera will store a *low-resolution* preview JPEG inside the RAW file. If you preview images on your camera, it is only able to show the low-resolution JPEG. If you zoom in to make sure it was properly focused, you will always see blurry pictures.
* However, if you shoot RAW+JPEG, the camera will use the *high-resolution* JPEG file for previews. This way you can actually use your camera to check if the focus was correct or not.
Now you can choose between two options: a bit more space on your memory card (RAW) vs. accurate on-camera previews (RAW+JPEG).
With Canon DSLRs you do not have the same issue, as the preview JPEGs that are stored in the RAW files are of a high enough resolution. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | I shoot JPEG + RAW when I use my older cameras with bad displays such as the 1Ds mk II. The display of that camera is almost useless (but the image quality is great) and I need another way of quickly confirm that focus is correct etc. I use a WiFi enabled memory card to transfer the JPEG:s to my tablet for quick review and then I import the RAW files to my computer for editing. | I don't know the actual reason for JPEG/RAW mode, but it's the mode I use most of the time.
Occasionally somebody asks me for a particular photo, and it's easier, faster, and more convenient to give them the JPEG than to load it on my laptop and edit in LightRoom or Capture One.
RAW + JPEG is also nice because sometimes the out of camera JPEG is "good enough," though I'll usually tweak it a bit anyway :-)
It can also be nice to compare how I've processed the file versus how my camera saved it as JPEG. Capture One and LightRoom support for my camera (Fujifilm X-Pro1) isn't great, and the camera's built in presets (Velvia, Standard, ...) aren't select-able in the apps, like they are for some cameras. Having the camera's JPEG along with the RAW lets me compare what I saw on the camera's screen with what I've done in the RAW processor. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | Depending on your camera, there might be a good reason to shoot JPEG + RAW even if your workflow is RAW-only: **accurate on-camera previews**.
Some cameras work like this (IIRC, I have seen this behaviour at least on Canon PowerShot S95):
* If you shoot RAW-only, the camera will store a *low-resolution* preview JPEG inside the RAW file. If you preview images on your camera, it is only able to show the low-resolution JPEG. If you zoom in to make sure it was properly focused, you will always see blurry pictures.
* However, if you shoot RAW+JPEG, the camera will use the *high-resolution* JPEG file for previews. This way you can actually use your camera to check if the focus was correct or not.
Now you can choose between two options: a bit more space on your memory card (RAW) vs. accurate on-camera previews (RAW+JPEG).
With Canon DSLRs you do not have the same issue, as the preview JPEGs that are stored in the RAW files are of a high enough resolution. | **In-camera .jpg produces more accurate colors.** At least, that is my experience, especially with artificial lighting.
For an example where post-production converters failed, see [here](https://photo.stackexchange.com/questions/29785/what-software-raw-converter-can-convert-from-raf-to-jpg-replicating-the-fujif).
Not only did Lightroom fail, but the raw converter *from the same manufacturer* could not even produce the right colors. I was really glad I happened to have raw+jpg enabled that day.
I have since tried to remember having jpg+raw enabled for artificial/stage lighting from then on. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | I shoot JPEG + RAW because my camera produces *really good JPEG output*. It has flexible control over tone curves, color, and contrast. I'm not usually interested in producing HDR-compressed images — in fact, I often prefer a high contrast look which reduces dynamic range. If I get the exposure and other settings right, I really don't benefit much from RAW.
If I make a mistake with white balance or am in a tricky situation, I have the RAW file to take advantage of. Most of the time, I develop that in-camera, using the built-in tools to do so, but in the cases where I'm not satisfied with that, I use RawTherapee. (My camera allows adjustment to the color of the LCD; it's not completely color profiled, but it's basically neutral, so I can trust my eye well enough.)
I know that some cameras only allow highly compressed "Basic" JPEG in combination with RAW; mine lets me save JPEGs of any quality, and in fact, I usually use ★★★, only increasing to ★★★★ when the scene needs it or when the image appears particularly special. (See [Is it worth using the Premium JPEG quality setting?](https://photo.stackexchange.com/questions/21690/pentax-k-5-is-it-worth-using-the-premium-jpeg-quality-setting))
And, in fact, in the interest of keeping my lifetime data load sane, I only keep the RAW files for those particularly special images. I know this is verging on sacrilege against the conventional wisdom, but I haven't regretted it yet. If I had *paying customers*, I'd definitely archive it all, just in case. | As a professional photographer I rarely need the jpeg files so I only turn them on when needed. When I do need them it is because I need a fast edit and raw files require a bit more processing time and CPU power than the average laptop can handle.
For instance I went to photograph a luncheon for a company where there was to be a few big name people speaking. When I arrived the contact told me he was told at the last minute that he needed a quick turn around on 5 of the images... a couple hours instead of having the entire shoot ready 6 hours to a day later. I turned on the raw + jpeg so I would have the ability to grab the jpeg quickly and do a quick edit and supply him the file quickly after the event when I got back to the office.
I've also had it where there were times when I could download the disk of images right on site when the client changed the deadline. They could have an untouched file immediately after shooting it, and they wouldn't need Photoshop, Lightroom or whatever program to convert a RAW file into something they could use.
Speed is the main reason to use Jpeg (size is another one). The reason to use raw is because it gives more latitude for adjustments and a wider color space, although the new jpeg revisions that just came out could make the wider color space a moot point. |
10,312 | DSLRs often have the ability to store both a JPEG and a raw file.
Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.
Why bother storing both JPEG and raw in camera, instead of just a raw file? | 2011/03/29 | [
"https://photo.stackexchange.com/questions/10312",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/378/"
] | My understanding is that the convention of RAW+JPEG started early in pro digital photography (like Sports Illustrated at a bowl game) when computers were slower than they are today and RAW file tools more cumbersome to use. The idea would be that Photo Editors would look through the JPEG files to find the shots they needed. They then sent the corresponding RAW files to the technicians who would convert and tone those images. It assumes a multi-person workflow.
That said, a lot of news organizations just used JPEG files -- especially when they had to transmit files on deadline over a land line modem. | As a professional photographer I rarely need the jpeg files so I only turn them on when needed. When I do need them it is because I need a fast edit and raw files require a bit more processing time and CPU power than the average laptop can handle.
For instance I went to photograph a luncheon for a company where there was to be a few big name people speaking. When I arrived the contact told me he was told at the last minute that he needed a quick turn around on 5 of the images... a couple hours instead of having the entire shoot ready 6 hours to a day later. I turned on the raw + jpeg so I would have the ability to grab the jpeg quickly and do a quick edit and supply him the file quickly after the event when I got back to the office.
I've also had it where there were times when I could download the disk of images right on site when the client changed the deadline. They could have an untouched file immediately after shooting it, and they wouldn't need Photoshop, Lightroom or whatever program to convert a RAW file into something they could use.
Speed is the main reason to use Jpeg (size is another one). The reason to use raw is because it gives more latitude for adjustments and a wider color space, although the new jpeg revisions that just came out could make the wider color space a moot point. |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | Did you check the whitepaper on the website?
[SQL Server 2008 Overview.](http://www.microsoft.com/sqlserver/2008/en/us/overview.aspx)
I cannot recall off the top of my head, but it atleast has a nice database to object linking functionality. They have geospatial types too, if you need to use those. | HotAdd CPU. <http://msdn.microsoft.com/en-us/library/bb964703.aspx> |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | There's a great article on the new T-SQL features [here](http://msdn.microsoft.com/en-us/library/cc721270.aspx) (by SQL guru Itzik Ben-Gan). It covers
* Declaring and initializing variables
* Compound assignment operators
* Table value constructor support through the VALUES clause
* Enhancements to the CONVERT function
* New date and time data types and functions
* Large UDTs (GEOMETRY and GEOGRAPHY)
* The HIERARCHYID data type
* Table types and table-valued parameters
* The MERGE statement, grouping sets enhancements
* DDL trigger enhancements
* Sparse columns
* Filtered indexes
* Large CLR user-defined aggregates
* Multi-input CLR user-defined aggregates
* The ORDER option for CLR table-valued functions
* Object dependencies
* Change data capture
* Collation alignment with Microsoft® Windows®
* Deprecation | HotAdd CPU. <http://msdn.microsoft.com/en-us/library/bb964703.aspx> |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | Filestream blob storage is the biggest bonus to me | Sparse indexing for those with lots of NULLs. Also the DATETIME2 data type that a lot of people have been waiting for 0001-01-01 through 9999-12-31. |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | Did you check the whitepaper on the website?
[SQL Server 2008 Overview.](http://www.microsoft.com/sqlserver/2008/en/us/overview.aspx)
I cannot recall off the top of my head, but it atleast has a nice database to object linking functionality. They have geospatial types too, if you need to use those. | [white paper on SQL Server 2008](http://download.microsoft.com/download/6/9/d/69d1fea7-5b42-437a-b3ba-a4ad13e34ef6/SQL2008_ProductOverview.docx)
This should cover most of the new features. I noticed the new date time data types and new security features. |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | Filestream blob storage is the biggest bonus to me | [white paper on SQL Server 2008](http://download.microsoft.com/download/6/9/d/69d1fea7-5b42-437a-b3ba-a4ad13e34ef6/SQL2008_ProductOverview.docx)
This should cover most of the new features. I noticed the new date time data types and new security features. |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | * New separate types for Date and Time, instead of just Datetime
* New geographic types for lattitude/longitude
* Change Data Capture is pretty neat if you're doing anything where auditing is important
* Configuration Servers, for maintaining multiple databases.
That's what caught my attention at the Heroes Happen Here launch back in April. | HotAdd CPU. <http://msdn.microsoft.com/en-us/library/bb964703.aspx> |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | * New separate types for Date and Time, instead of just Datetime
* New geographic types for lattitude/longitude
* Change Data Capture is pretty neat if you're doing anything where auditing is important
* Configuration Servers, for maintaining multiple databases.
That's what caught my attention at the Heroes Happen Here launch back in April. | [white paper on SQL Server 2008](http://download.microsoft.com/download/6/9/d/69d1fea7-5b42-437a-b3ba-a4ad13e34ef6/SQL2008_ProductOverview.docx)
This should cover most of the new features. I noticed the new date time data types and new security features. |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | Filestream blob storage is the biggest bonus to me | HotAdd CPU. <http://msdn.microsoft.com/en-us/library/bb964703.aspx> |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | Did you check the whitepaper on the website?
[SQL Server 2008 Overview.](http://www.microsoft.com/sqlserver/2008/en/us/overview.aspx)
I cannot recall off the top of my head, but it atleast has a nice database to object linking functionality. They have geospatial types too, if you need to use those. | Page compressiong sounds really nice to me. Haven't used it yet, though.
<http://sqlblog.com/blogs/linchi_shea/archive/2008/05/11/sql-server-2008-page-compression-compression-ratios-from-real-world-databases.aspx> |
75,487 | I'm looking mainly at things like new SQL syntax, new kinds of locking, new capabilities etc. Not so much in the surrounding services like data warehousing and reports... | 2008/09/16 | [
"https://Stackoverflow.com/questions/75487",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/5777/"
] | * New separate types for Date and Time, instead of just Datetime
* New geographic types for lattitude/longitude
* Change Data Capture is pretty neat if you're doing anything where auditing is important
* Configuration Servers, for maintaining multiple databases.
That's what caught my attention at the Heroes Happen Here launch back in April. | Page compressiong sounds really nice to me. Haven't used it yet, though.
<http://sqlblog.com/blogs/linchi_shea/archive/2008/05/11/sql-server-2008-page-compression-compression-ratios-from-real-world-databases.aspx> |
146,341 | What sort of fireproof liquid could be used by carbon-based life without causing harm to the organism? Whether it be absorbed from exterior sources or produced in the organism's body. I say organism due to the fact that is not an animal, it is most similar to plant life. The purpose of the fireproof liquid is to prevent combustion altogether. These plants have had plenty of time in a high oxygen environment to develop these qualities. | 2019/05/04 | [
"https://worldbuilding.stackexchange.com/questions/146341",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/64584/"
] | **Terminally oxidized things do not burn.**
By terminally oxidized I mean there is a base molecule and then oxidants stuck on to the point oxygen cannot find more room to stick itself on. Oxygen sticking itself onto things = burning.
1. Water. Hydrogen with 2 oxygens stuck on.
2. [Carbon tetrachloride](https://en.wikipedia.org/wiki/Carbon_tetrachloride). It is not acutely toxic like bromine and it used to be a popular household solvent. It was in fire extinguishers. It causes chronic liver toxicity in humans so is no longer available. It might not work that way with everything.
3. [Elemental mercury](https://en.wikipedia.org/wiki/Mercury_poisoning) as the liquid.
>
> Quicksilver (liquid metallic mercury) is poorly absorbed by ingestion
> and skin contact. Its vapor is the most hazardous form. Animal data
> indicate less than 0.01% of ingested mercury is absorbed through the
> intact gastrointestinal tract, though it may not be true for
> individuals suffering from ileus. Cases of systemic toxicity from
> accidental swallowing are rare, and attempted suicide via intravenous
> injection does not appear to result in systemic toxicity,[27] though
> it still causes damage by physically blocking blood vessels both at
> the site of injection and the lungs. Though not studied
> quantitatively, the physical properties of liquid elemental mercury
> limit its absorption through intact skin and in light of its very low
> absorption rate from the gastrointestinal tract, skin absorption would
> not be high
>
>
>
4. [Perfluorocarbons](https://en.wikipedia.org/wiki/Fluorocarbon). These are the liquids used for partial liquid ventilations. This is the stuff that mice are running around in, breathing. They are not flammable because fluorines and chlorines are taking up all the space on the carbon. I suppose carbon tetrachloride is technically one of these too.
5. Cyclomethicones. <https://en.wikipedia.org/wiki/Siloxane>
>
> Cyclomethicones are a group of methyl siloxanes, a class of liquid
> silicones (cyclic polydimethylsiloxane polymers) that possess the
> characteristics of low viscosity and high volatility as well as being
> skin emollients and in certain circumstances useful cleaning solvents...
>
>
>
Nifty stuff but artificial. | If you are aiming for a conventional fireproofing solution, Hoyle's answer is probably the best. Water is nonflammable, has an very high heat capacity, is abundant, and obviously nontoxic.
That said, humans contain a great deal of water and yet are still vulnerable to fire. If you want creatures that are much more resistant to flames, I would try insulating their skin, instead of attempting to make their biology inherently flame retardant.
If you are okay using an ablative heat shield (which would need to be replenished over time, but that is fine if it is part of a living organism), something like [Starlite](https://en.wikipedia.org/wiki/Starlite) could do the trick (the original formula for the insulator is actually unknown, but a really good imitation can be made with simple household ingredients). When exposed to fire, it releases a layer of CO2 just above its surface, repelling the flames. It also forms a black coating on the surface that radiates heat extremely well. Combining these two properties, a thin coating of the stuff can protect quite well against fire (some videos showcase it being able to keep an egg uncooked with direct exposure to a welding torch).
The chemistry of the stuff is pretty simple, and you could probably come up with a biological analogue for it. That, or you could just give the creature thick skin/scales made of a decent insulator, so it could survive fire at least for a little while.
If you want the creature to be comfortable in flames for a prolonged amount of time, the main challenge after insulating it from the heat is breathing. You would need to be able to filter out the smoke, and also deal with breathing in superheated air. You could try giving it a long-ish and more heat-resistant windpipe (not necessarily in a straight line though, so a long neck is not required) to filter the air and also absorb/radiate off some of that heat before it reaches the lungs. This is a bit inefficient for creatures on earth but if surviving fire is a requirement it's not out of the question.
That, or the creatures would need to be capable of holding their breath for a long time. Certain whales can hold their breath for 90 minutes. |
146,341 | What sort of fireproof liquid could be used by carbon-based life without causing harm to the organism? Whether it be absorbed from exterior sources or produced in the organism's body. I say organism due to the fact that is not an animal, it is most similar to plant life. The purpose of the fireproof liquid is to prevent combustion altogether. These plants have had plenty of time in a high oxygen environment to develop these qualities. | 2019/05/04 | [
"https://worldbuilding.stackexchange.com/questions/146341",
"https://worldbuilding.stackexchange.com",
"https://worldbuilding.stackexchange.com/users/64584/"
] | **Water**
As has been stated, water is fireproof and extinguishes most flames (certain chemical fires can not be extinguished, even if submerged in water).
[](https://i.stack.imgur.com/dfiPR.jpg)
[Redwood trees famously use water to resist fire](https://news.nationalgeographic.com/news/2013/08/130826-giant-sequoias-yosemite-rim-fire-forestry-science/#/70716.jpg), their high water content prevents them from burning, a useful adaptation as the forests they live in are prone to fires (which are actually beneficial to the redwoods as the fire kills off competition). Your race of plants may do a similar thing, having a very high water content to allow them to resist fire. If water is good enough to allow a 250ft tree to survive thousands of years worth of forest fires, it should certainly be enough to make your plant race fireproof (or at least fire resistant as nothing is truly fireproof, enough heat will burn anything). | If you are aiming for a conventional fireproofing solution, Hoyle's answer is probably the best. Water is nonflammable, has an very high heat capacity, is abundant, and obviously nontoxic.
That said, humans contain a great deal of water and yet are still vulnerable to fire. If you want creatures that are much more resistant to flames, I would try insulating their skin, instead of attempting to make their biology inherently flame retardant.
If you are okay using an ablative heat shield (which would need to be replenished over time, but that is fine if it is part of a living organism), something like [Starlite](https://en.wikipedia.org/wiki/Starlite) could do the trick (the original formula for the insulator is actually unknown, but a really good imitation can be made with simple household ingredients). When exposed to fire, it releases a layer of CO2 just above its surface, repelling the flames. It also forms a black coating on the surface that radiates heat extremely well. Combining these two properties, a thin coating of the stuff can protect quite well against fire (some videos showcase it being able to keep an egg uncooked with direct exposure to a welding torch).
The chemistry of the stuff is pretty simple, and you could probably come up with a biological analogue for it. That, or you could just give the creature thick skin/scales made of a decent insulator, so it could survive fire at least for a little while.
If you want the creature to be comfortable in flames for a prolonged amount of time, the main challenge after insulating it from the heat is breathing. You would need to be able to filter out the smoke, and also deal with breathing in superheated air. You could try giving it a long-ish and more heat-resistant windpipe (not necessarily in a straight line though, so a long neck is not required) to filter the air and also absorb/radiate off some of that heat before it reaches the lungs. This is a bit inefficient for creatures on earth but if surviving fire is a requirement it's not out of the question.
That, or the creatures would need to be capable of holding their breath for a long time. Certain whales can hold their breath for 90 minutes. |
13,256 | I was asked to today about the available plans (in Israel) to install photo-voltaic receptors on the roof and sell the energy. This is a legitimate plan and there are several companies that do this. The claim is that the initial investment is repaid after roughly 5 years which sounds too optimistic to me. I want to carry the calculation myself and check the results. Where can I find some data about the light flux that hit the earth in a typical year?
*note*
I'm not sure, since this is not my specific field of expertise, about the commonly used term. | 2011/08/07 | [
"https://physics.stackexchange.com/questions/13256",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/3677/"
] | It will vary a lot by site, and on the particular PV technology being proposed.
So, you need to know:
* is it monocrystalline silicon, is it CdTe thin-film, or something else?
* what's the efficiency of the inverter?
* what's the guarantee on the kit (5 years, 10 years, 20 years)?
Using @Martin Beckett's figure of 2000kWh/y, that means, roughly, that your annual production would be approximately 2000 hours x the installed capacity of your PV array. So if you had a 1kW capacity system, you might expect to get 2 000 kWh of electricity in an average year.
That's assuming an equator-facing PV array tilted to the optimum angle for your location; and, crucially, that there aren't any objects that would cast shadows over your PV array. Depending on the particular panels and inverter configuration, a bit of shadowing can reduce generation by 10-80%.
There are various PV calculators around on the web - the good ones should ask you my top two questions above, about panel type and efficiency). The [USA NREL PVWATTS calculator](http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/) has no sites in Israel - the closest is Cairo - but I expect you'll be able to find a reliable one somewhere that will run the numbers for you. The [EU PVGIS calculator](http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?map=africa) looks like it covers Israel, so I'd recommend trying that out.
Five years might be a plausible payback time, depending on how much you'd get paid per kWh; how much you'd save off your bills; and how much the installation costs are. Currently, I expect you'd be asked to pay of the order of €3/W of installed capacity (before any subsidies or taxes). So, at the above generation rate of 2kWh/W/y, then a five-year payback would imply that you'd be getting paid (in direct payment + bill savings) about €0.30/kWh (assuming a zero discount rate).
Panel efficiency has already been taken account of, in the above calculation of power output and of payback time. That is to say, once you know the panel's rated capacity, you've already accounted for the panel's efficiency. For more info on PV efficiency itself, see [this answer to another question](https://physics.stackexchange.com/questions/2656/how-bright-can-we-make-a-sun-jar/13199#13199). To calculate the efficiency of any given panel, take its rated power in kW, and divide by its surface area in square metres. For example, a 200 W panel that is 1 square metre has an efficiency of 0.2 / 1.0 = 0.2 = 20%. Typical commercial panels currently are in the range 10% (thin film) - 20% (best monocrystalline).
An annual insolation of 2000 kWh, means that 2000 kWh of sunlight falls on $1m^2$ in an average year. If you want to put panel efficiency in there too, you end up putting it in the numerator and denominator, and it all cancels out, leaving you just with 2000 hours x PV capacity in kW.
Now, that factor of 2000 gets derated by various things: panel shading, inverter efficiency, less-than-optimal tilt or orientation, system down-time, and so on. | For the middle east, typically around 2000 KWh/m^2/year
A good place to start is wiki page for [insolation](http://en.wikipedia.org/wiki/Insolation) (technical term for sunlight arriving) |
9,384,746 | Is there a way to realize tabs in Multimarkdown syntax?
My Goal is something like:
* Item:-----------tab------->Value
* An other item:---tab--->Value
* And one item more:--->Value
I could realize that by a [table](https://stackoverflow.com/a/4058964/641514), but this would be an overhead. I'd love it to stay a list. | 2012/02/21 | [
"https://Stackoverflow.com/questions/9384746",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/641514/"
] | You can type "tab" characters wherever you like. But there is no concept of alignment outside of a table since there is no way to know whether the resulting output will be displayed in a monospace or variable-width font. And since Markdown/MultiMarkdown eat unnecessary whitespace, the extra spaces would be stripped from the resulting output.
A list is designed to display sequential data. A table is designed to show tabular data. It seems that you want to show tabular data, but are trying to force it into a format that wasn't designed for that purpose.
So the concise answer to your question is "No". | >
> but are trying to force it into a format that wasn't designed for that purpose.
>
>
>
If you go back to typewriters the purpose of tabstops original where tables ;)
It is really a pity that elastic tabstops and .tsv text files (instead .csv with comma or semicolon as separator depending on region) are not common today. The easiest way to write a table is simply hitting tab. It is also the easiest way to read tabular data in columns. Only for the programmers of the first text editing programs it was easier to show every tab character simply as 4 spaces. The Elastic Tabstops feature shows consecutive lines of text with tab characters in table columns.
In a perfect world we had plain text tables everywhere easy to write and read thanks to Elastic Tabstops. Unfortunately it seems not easy to implement in existing text engines. |
38,183 | I've heard claims ranging from *"higher-quality lenses only make a noticeable difference for scientific applications and super-huge prints,"* to *"even the difference between high-quality and uber-high-quality lenses can be seen with the naked eye on 6x10 prints"*
Before I sell my house so I can take amazing pictures from a cardboard box, I'd like to actually see the difference. However, all the examples I've found compare photos not only from different lens, but also with different cameras/scenes/photographers!
**Are there any examples of the same scene, with the exact same settings on the same camera, taken with multiple lenses (of differing quality/price)?** Multiple comparisons with different scenes/cameras *(especially cameras of different qualities)* would be preferable, to eliminate any variables. I'd also prefer a non-biased source *(so, not the lens-manufacturer)*.
I'd also be interested in comparing telephoto to zoom+teleconverter *(of the same quality, focal-length etc.)*, or comparing zoom to fixed-length... but perhaps those are asking too much :) | 2013/04/17 | [
"https://photo.stackexchange.com/questions/38183",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/4848/"
] | Sure; this is exactly what what <http://photozone.de> does in lens reviews. The sample images aren't always exactly the same but show similar subjects, but the technical analysis is all done for each lens on the same camera (for each brand).
For example, the sample images for Pentax's [70mm DA Limited](http://www.photozone.de/pentax/127-pentax-smc-da-70mm-f24-limited-review--test-report?start=2) and earlier [77mm FA Limited](http://www.photozone.de/pentax/128-pentax-smc-fa-77mm-f18-limited-review--test-report?start=2) show statues in the same garden from roughly the same viewpoint, but they're taken in different days and without mechanical precision. However, the *technical* analysis, done on an optical bench and shown on the previous pages are done in a controlled environment.
If you want super-identical images, reality limits that to still-life studio setups; other Lens review sites like [SLR Gear](http://slrgear.com/reviews/showcat.php/cat/2) will have those; see for example the the Pentax [40mm DA Limited](http://slrgear.com/reviews/zproducts/pentax40f28/zz_sampleindex.htm) and [43mm FA Limited](http://slrgear.com/reviews/zproducts/pentax43f19/zz_sampleindex.htm). You can see both a studio still-life and a test target. **These images, by their nature, are pretty dull and can't really tell you the whole story of the lens.**
The Digital Picture site linked to in other answers also shows test target images, without even a studio still-life. You may find DPReview's [Lens Comparator Widget](http://www.dpreview.com/lensreviews/widget/Fullscreen.ashx?reviews=36,51&fullscreen=true&av=1,1&fl=50,55&vis=VisualiserSharpnessMTF,VisualiserSharpnessMTF&stack=horizontal&&config=/lensreviews/widget/LensReviewConfiguration.xml?4) similarly helpful; it gives a colorful presentation of results and you can hover over parts of the image for actual crops from the test target. But really, I can't see much advantage of staring at test targets yourself over looking at the crunched data and reading what the reviewers are saying.
As I re-read your question, though, I think that what you're *actually* asking may be best covered by **[What characteristics make a good lens good?](https://photo.stackexchange.com/questions/25572/what-characteristics-make-a-good-lens-good)**, which goes into what exactly the practical, visible differences are between higher-quality lenses and what you might want to look for in any samples. Once you know what you're looking for, it's not really important for the test images to be exactly identical. | The only relatively comprehensive comparison I know of is [The Digital Picture](http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=787&Sample=0&FLI=0&API=0&LensComp=119&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=1). They are limited to mostly (only?) Canon, and use only one photo, a test chart.
Apart from that, there are a number of individual "shootout" reviews comparing a small number of lenses, like [this one](http://kenrockwell.com/nikon/comparisons/DX-super-zooms/index.htm). You'll have to hunt them down one by one. |
38,183 | I've heard claims ranging from *"higher-quality lenses only make a noticeable difference for scientific applications and super-huge prints,"* to *"even the difference between high-quality and uber-high-quality lenses can be seen with the naked eye on 6x10 prints"*
Before I sell my house so I can take amazing pictures from a cardboard box, I'd like to actually see the difference. However, all the examples I've found compare photos not only from different lens, but also with different cameras/scenes/photographers!
**Are there any examples of the same scene, with the exact same settings on the same camera, taken with multiple lenses (of differing quality/price)?** Multiple comparisons with different scenes/cameras *(especially cameras of different qualities)* would be preferable, to eliminate any variables. I'd also prefer a non-biased source *(so, not the lens-manufacturer)*.
I'd also be interested in comparing telephoto to zoom+teleconverter *(of the same quality, focal-length etc.)*, or comparing zoom to fixed-length... but perhaps those are asking too much :) | 2013/04/17 | [
"https://photo.stackexchange.com/questions/38183",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/4848/"
] | Sure; this is exactly what what <http://photozone.de> does in lens reviews. The sample images aren't always exactly the same but show similar subjects, but the technical analysis is all done for each lens on the same camera (for each brand).
For example, the sample images for Pentax's [70mm DA Limited](http://www.photozone.de/pentax/127-pentax-smc-da-70mm-f24-limited-review--test-report?start=2) and earlier [77mm FA Limited](http://www.photozone.de/pentax/128-pentax-smc-fa-77mm-f18-limited-review--test-report?start=2) show statues in the same garden from roughly the same viewpoint, but they're taken in different days and without mechanical precision. However, the *technical* analysis, done on an optical bench and shown on the previous pages are done in a controlled environment.
If you want super-identical images, reality limits that to still-life studio setups; other Lens review sites like [SLR Gear](http://slrgear.com/reviews/showcat.php/cat/2) will have those; see for example the the Pentax [40mm DA Limited](http://slrgear.com/reviews/zproducts/pentax40f28/zz_sampleindex.htm) and [43mm FA Limited](http://slrgear.com/reviews/zproducts/pentax43f19/zz_sampleindex.htm). You can see both a studio still-life and a test target. **These images, by their nature, are pretty dull and can't really tell you the whole story of the lens.**
The Digital Picture site linked to in other answers also shows test target images, without even a studio still-life. You may find DPReview's [Lens Comparator Widget](http://www.dpreview.com/lensreviews/widget/Fullscreen.ashx?reviews=36,51&fullscreen=true&av=1,1&fl=50,55&vis=VisualiserSharpnessMTF,VisualiserSharpnessMTF&stack=horizontal&&config=/lensreviews/widget/LensReviewConfiguration.xml?4) similarly helpful; it gives a colorful presentation of results and you can hover over parts of the image for actual crops from the test target. But really, I can't see much advantage of staring at test targets yourself over looking at the crunched data and reading what the reviewers are saying.
As I re-read your question, though, I think that what you're *actually* asking may be best covered by **[What characteristics make a good lens good?](https://photo.stackexchange.com/questions/25572/what-characteristics-make-a-good-lens-good)**, which goes into what exactly the practical, visible differences are between higher-quality lenses and what you might want to look for in any samples. Once you know what you're looking for, it's not really important for the test images to be exactly identical. | I'm not sure you'll find one site that compares all lenses with one realistic scene, but a few lens review sites I've found interesting in the past include
* [Ken Rockwell's Camera and Lens Reviews](http://www.kenrockwell.com/tech/reviews.htm) Has reviews of high-end Canon and Nikon lenses, and he's not afraid to tell you to buy the cheaper models if he doesn't see any real difference in image quality (and he offers photographic evidence to make his case).
* [Camera Labs' lens reviews](http://www.cameralabs.com/lenses/Latest_DSLR_Lens_reviews.shtml) Reviews and round-ups between mostly mid-range Canon and Nikon zooms.
* [Digital Photography Review - lenses](http://www.dpreview.com/lensreviews/) Technical reviews of lenses, which offers a comparison feature which comares lens sharpness rather than side-by-side scene images.
Pentax lenses don't feature hugely on these sites, but they might illustrate whether top-end lenses really offer enough extra quality to justify their considerably higher price. And Ken Rockwell's site will probably just tell you to save your money and spend it on going out to find things worth photographing anyhow. |
38,183 | I've heard claims ranging from *"higher-quality lenses only make a noticeable difference for scientific applications and super-huge prints,"* to *"even the difference between high-quality and uber-high-quality lenses can be seen with the naked eye on 6x10 prints"*
Before I sell my house so I can take amazing pictures from a cardboard box, I'd like to actually see the difference. However, all the examples I've found compare photos not only from different lens, but also with different cameras/scenes/photographers!
**Are there any examples of the same scene, with the exact same settings on the same camera, taken with multiple lenses (of differing quality/price)?** Multiple comparisons with different scenes/cameras *(especially cameras of different qualities)* would be preferable, to eliminate any variables. I'd also prefer a non-biased source *(so, not the lens-manufacturer)*.
I'd also be interested in comparing telephoto to zoom+teleconverter *(of the same quality, focal-length etc.)*, or comparing zoom to fixed-length... but perhaps those are asking too much :) | 2013/04/17 | [
"https://photo.stackexchange.com/questions/38183",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/4848/"
] | Sometimes I think I could sit and play with [The Digital Picture](http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx) all day staring and lens quality comparisons, along with different camera backs. It's a highly useful site. | The only relatively comprehensive comparison I know of is [The Digital Picture](http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=787&Sample=0&FLI=0&API=0&LensComp=119&CameraComp=453&SampleComp=0&FLIComp=0&APIComp=1). They are limited to mostly (only?) Canon, and use only one photo, a test chart.
Apart from that, there are a number of individual "shootout" reviews comparing a small number of lenses, like [this one](http://kenrockwell.com/nikon/comparisons/DX-super-zooms/index.htm). You'll have to hunt them down one by one. |
38,183 | I've heard claims ranging from *"higher-quality lenses only make a noticeable difference for scientific applications and super-huge prints,"* to *"even the difference between high-quality and uber-high-quality lenses can be seen with the naked eye on 6x10 prints"*
Before I sell my house so I can take amazing pictures from a cardboard box, I'd like to actually see the difference. However, all the examples I've found compare photos not only from different lens, but also with different cameras/scenes/photographers!
**Are there any examples of the same scene, with the exact same settings on the same camera, taken with multiple lenses (of differing quality/price)?** Multiple comparisons with different scenes/cameras *(especially cameras of different qualities)* would be preferable, to eliminate any variables. I'd also prefer a non-biased source *(so, not the lens-manufacturer)*.
I'd also be interested in comparing telephoto to zoom+teleconverter *(of the same quality, focal-length etc.)*, or comparing zoom to fixed-length... but perhaps those are asking too much :) | 2013/04/17 | [
"https://photo.stackexchange.com/questions/38183",
"https://photo.stackexchange.com",
"https://photo.stackexchange.com/users/4848/"
] | Sometimes I think I could sit and play with [The Digital Picture](http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx) all day staring and lens quality comparisons, along with different camera backs. It's a highly useful site. | I'm not sure you'll find one site that compares all lenses with one realistic scene, but a few lens review sites I've found interesting in the past include
* [Ken Rockwell's Camera and Lens Reviews](http://www.kenrockwell.com/tech/reviews.htm) Has reviews of high-end Canon and Nikon lenses, and he's not afraid to tell you to buy the cheaper models if he doesn't see any real difference in image quality (and he offers photographic evidence to make his case).
* [Camera Labs' lens reviews](http://www.cameralabs.com/lenses/Latest_DSLR_Lens_reviews.shtml) Reviews and round-ups between mostly mid-range Canon and Nikon zooms.
* [Digital Photography Review - lenses](http://www.dpreview.com/lensreviews/) Technical reviews of lenses, which offers a comparison feature which comares lens sharpness rather than side-by-side scene images.
Pentax lenses don't feature hugely on these sites, but they might illustrate whether top-end lenses really offer enough extra quality to justify their considerably higher price. And Ken Rockwell's site will probably just tell you to save your money and spend it on going out to find things worth photographing anyhow. |
15,376 | I suspect that my site is penalized by Google.
Is there a way to check if it's true?
EDIT:
Webmaster Tools don't show any messages. Sometimes there are warnings about inaccessible (404, Soft 404s) pages on the site that come and go, and couple of warnings about duplicate page titles (in online documentation for my software), though. | 2011/06/15 | [
"https://webmasters.stackexchange.com/questions/15376",
"https://webmasters.stackexchange.com",
"https://webmasters.stackexchange.com/users/2545/"
] | Google will contact webmasters through their [Webmasters Tools](https://www.google.com/webmasters/tools/home?hl=en) page to let them know there is an issue with their site. If you don't already have an account sign up for one and see if a message is there for you. | Ok, I did read some other sites and I think I got the answer for my question.
If someone else is interested, following links have helped me:
* [How to Handle a Google Penalty](http://moz.com/blog/how-to-handle-a-google-penalty-and-an-example-from-the-field-of-real-estate) (contains good flowchart)
* [10 Ways to Diagnose a Google Penalty](http://www.searchenginejournal.com/10-ways-to-diagnose-a-google-penalty/) |
193,747 | Came across an Adafruit interview with the one and only Paul Horowitz and he said something interesting. [Part of interview thats related to this question](https://youtu.be/iCI3B5eT9NA?t=26m45s)
He said in more or less words that the capacitance of a line disappears when the cable is terminated.
Why does adding resistance "removes" capacitance ? If this is not what is implied in the video, then an interpretation of what he meant and small explanation would work. **The focus of this question is about the capacitance.**
And it's not that the resistance dominates, so capacitance is negligible, he says its actually gone. Magic.
Can someone call Howard Johnson about this ? Paul Horowitz is dabbin in black magic. | 2015/10/06 | [
"https://electronics.stackexchange.com/questions/193747",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/9409/"
] | It depends what you mean by 'capacitance'. If you mean two conductors separated by dielectric, then of course it doesn't.
However, if you mean 'behaves like capacitor', then yes it does.
a) If you take (for instance) a high value resistor from a power supply, and connect it to a capacitor, then the voltage will start at 0v and slowly ramp up.
b) If you take the same resistor and supply, and connect it to a 50 ohm resistor, the voltage will jump up as soon as connected to some value determined by the resistor ratio, and stay there.
c) If you take the same resistor and supply, and connect it to any length of 50 ohm line *terminated with a 50 ohm resistor*, it will behave just like (b).
d) This is where it gets interesting. If you take the same resistor and supply, and connect it to an open circuited length of 50 ohm transmission line, then it will behave like (b), at first. The voltage goes up to a 50ohm value, and stays there. It stays there for as long as the voltage wave travels along the line, and still stays there while the reflection wave travels back. When the reflection wave gets back to the resistor end, the voltages add and further reflections take place. As the reflections travel to and fro, the 'capacitive' behaviour emerges. This is where you need to find a video tutorial on transmission lines.
So why is that different from (c)? When the travelling wave hit the terminating resistor, it was not reflected. Everything stopped changing, with a DC current flowing through the high value resistor, along the line, and through the terminating resistor.
e) What happens if the line is short circuited at the end? As for (d), except as the reflections build up, 'inductive' behaviour emerges.
So you can see that the 'normal' behaviour of a transmission line is resistive. It's only after the time it takes for the speed of light to make several trips along the line that the capacitive or inductive behaviour emerges. As the time for this behaviour to build up depends on the length of the line, so does the effective capacitance or inductance also depend on the length of the line. | The [distributed] capacitance is said to disappear in the sense that there are no standing waves when a transmission line is terminated in a resistor that equals the characteristic impedance of the line. In that case, V and I along the line look like in the 1st (or 2nd) graph[s] below, i.e. they are always in phase. The difference between these first two is whether the line has any resistive losses. This is the "magic" that Horowitz is talking about, i.e. V and I along the line look as if the line is purely resistive when properly terminated.
You can see that in the subsequent graphs V and I along the line are never always in phase (i.e. there's a capacitive/inductive effect), even if the line is terminated with a resistor, but of a different value than the line's characteristic impedance. Furthermore, in all graphs but the first two, there are minimima and maxima along the line. It's these minima and maxima that Horowitz was talking about (in the case of an open-ended cable) [prior](https://youtu.be/iCI3B5eT9NA?t=1532) to his "magic" remark. More precisely he was talking about how varying the generator's signal frequency results in different amplitudes measured at the far end of the cable, which is not hard to see from the 3rd graph below could happen. Then he talks about how adding a matching terminator makes the signal snap back from [a] zero as if magic happens.
[](https://i.stack.imgur.com/ko6ZN.png)
The calculations proving this happens (actual "why") are a bit involved. I suggest you consult a[ny] textbook dealing with transmission lines, including [the one](https://books.google.com/books?id=1YA1NZuo6u0C&pg=PA150) from which I borrowed this image. Actually [Wikipedia has the derivations too](https://en.wikipedia.org/wiki/Reflections_of_signals_on_conducting_lines), but it's not the most mathematically clear presentation I saw (and its illustrations in this case are rather lackluster). |
8,067 | I was recently graced with a new job opportunity in a large higher ed NE department. This is my first job working with a large network of several thousand users.
Throughout my education, I followed the idea that **static IP's are useful from time to time in certain applications and historically used more in smaller networks**. To this point, it has been my belief up to this point that **DHCP is much more useful in larger settings**. For this reason, I was shocked to learn that **each of our near 3000 networking devices have painstakingly been allocated static management IP addresses**. It was explained that this was easier to handle that DHCP.
I will admit, the scheme for the addressing is nifty. The **second octet is the device-class/network identifier**, the **third octet is the building identifier** (we have some odd 200 buildings on campus), and the **fourth is the device identifier**.
So the scheme is understandable, but still seems like a lot of numbers to remember; imagine I am looking for a Xirrus array in say the Cafeteria on St. Phillip's Street. Yes DNS could solve this, but the IP's do sometimes get changed and that could result in a nightmare if one is changed and not the other.
The solution to me seems a DHCP/DNS combo.
So to sum up the question, **from a management standpoint, why is it a good idea to use Static or DHCP addressing on equipment?** | 2014/05/24 | [
"https://networkengineering.stackexchange.com/questions/8067",
"https://networkengineering.stackexchange.com",
"https://networkengineering.stackexchange.com/users/5785/"
] | I’ll keep this post about your situation specifically.
First and foremost, managing over 3,000 devices with static IP addresses is just plain foolish. DHCP is a well-known and established protocol that solves the tedious task of manually assigning and fixing manual IP addresses. If they are that concerned about making sure they have control over **every** IP address on their network, set them as DHCP reservations. Even from a security standpoint, you don’t stand to benefit *that* much from eliminating DHCP servers.
By sticking with this route, you will lose:
* **Change management capabilities**
* Customer insight
The big hitter on this list is change management capabilities. If you need to swap IPs around, you really don’t have a good way to do this; and that makes (or will make) your life arduous. If your teammates aren't on board with it and want to stick with their old ways, try to rope in your management and inform them of what a colossal waste of time it is.
Regarding your nifty IP scheme; you will still be able to maintain that; If anything, to a greater degree. [IPAM](https://networkengineering.stackexchange.com/questions/7250/what-is-ip-address-management-why-its-needed-how-does-the-vendors-like-bluec/7253#7253) gives you the capability to drill down into smaller and smaller subnet ranges, making it seemingly easy to implement in your case. This will allow you to cascade further and further down into the building/device class you desire. | The answer to your question is mostly opinion, which is frowned upon on this forum. But I'm willing to bet real money that the majority of people here will agree with me.
I suppose that for some people, spending lots of time with Excel spreadsheets, keeping track of multiple spreadsheet versions, and the intellectual challenge of troubleshooting duplicate address problems are all enjoyable, but that's really no way to manage a network. I won't speculate on why DHCP was never implemented (*cough* fear \*cough), but DHCP will help you manage your network more effectively by freeing you up from doing a lot of mundane tasks that can and should be automated.
I should point out that not everything will use DHCP. Your routers, switches, firewalls, some servers, will need static addresses. But the majority of devices, especially end user PCs, wireless devices, printers, etc. should use DHCP.
What you really need is an IP address management application, or IPAM. There are commercial products as well as freeware that manage both DHCP scopes and static addresses.
You don't have to give up your nifty addressing scheme either. You can create DHCP "scopes" for each of your locations and device types.
Certain devices that need stable addresses (like printers) can use DHCP reservations, so you can manage their addresses from a single application. That saves a lot of "running around" time.
In addition, you can use dynamic DNS, that syncs DHCP and DNS so that when an address is leased, a DNS entry is automatically created. Your Xirrus AP will always have the same name no matter where it is. |
8,067 | I was recently graced with a new job opportunity in a large higher ed NE department. This is my first job working with a large network of several thousand users.
Throughout my education, I followed the idea that **static IP's are useful from time to time in certain applications and historically used more in smaller networks**. To this point, it has been my belief up to this point that **DHCP is much more useful in larger settings**. For this reason, I was shocked to learn that **each of our near 3000 networking devices have painstakingly been allocated static management IP addresses**. It was explained that this was easier to handle that DHCP.
I will admit, the scheme for the addressing is nifty. The **second octet is the device-class/network identifier**, the **third octet is the building identifier** (we have some odd 200 buildings on campus), and the **fourth is the device identifier**.
So the scheme is understandable, but still seems like a lot of numbers to remember; imagine I am looking for a Xirrus array in say the Cafeteria on St. Phillip's Street. Yes DNS could solve this, but the IP's do sometimes get changed and that could result in a nightmare if one is changed and not the other.
The solution to me seems a DHCP/DNS combo.
So to sum up the question, **from a management standpoint, why is it a good idea to use Static or DHCP addressing on equipment?** | 2014/05/24 | [
"https://networkengineering.stackexchange.com/questions/8067",
"https://networkengineering.stackexchange.com",
"https://networkengineering.stackexchange.com/users/5785/"
] | I suppose it boils down to what you mean by *networking devices*. Routers, switches, firewalls, access points, etc., etc. do need to have fixed, known locations. It's a bad idea to rely on DHCP and DNS -- even where "sticky" addresses are used.
One network fault is all it takes to learn how bad an idea that is... say your network is broken *somewhere*. You (in fact, the entire engineering department) happen to be on the side that cannot reach DNS, and probably DHCP too. If all of your gear has random, unknown DHCP assigned addresses, you'll have no map, and no access to create one. If your workstation is portable, off, etc. *you* may not have an address from which to work. Various networking devices may start dropping off the network as their leases expire, other devices (like your laptop) coming online for the day won't have an address, rebooted equipment won't have addresses... A failure of the DHCP server will net a similar effect. A failure of the DNS server(s) will leave a mess of old, invalid registrations, and a bunch of holes where new registrations didn't happen -- nothing I know of will retry. | The answer to your question is mostly opinion, which is frowned upon on this forum. But I'm willing to bet real money that the majority of people here will agree with me.
I suppose that for some people, spending lots of time with Excel spreadsheets, keeping track of multiple spreadsheet versions, and the intellectual challenge of troubleshooting duplicate address problems are all enjoyable, but that's really no way to manage a network. I won't speculate on why DHCP was never implemented (*cough* fear \*cough), but DHCP will help you manage your network more effectively by freeing you up from doing a lot of mundane tasks that can and should be automated.
I should point out that not everything will use DHCP. Your routers, switches, firewalls, some servers, will need static addresses. But the majority of devices, especially end user PCs, wireless devices, printers, etc. should use DHCP.
What you really need is an IP address management application, or IPAM. There are commercial products as well as freeware that manage both DHCP scopes and static addresses.
You don't have to give up your nifty addressing scheme either. You can create DHCP "scopes" for each of your locations and device types.
Certain devices that need stable addresses (like printers) can use DHCP reservations, so you can manage their addresses from a single application. That saves a lot of "running around" time.
In addition, you can use dynamic DNS, that syncs DHCP and DNS so that when an address is leased, a DNS entry is automatically created. Your Xirrus AP will always have the same name no matter where it is. |
8,067 | I was recently graced with a new job opportunity in a large higher ed NE department. This is my first job working with a large network of several thousand users.
Throughout my education, I followed the idea that **static IP's are useful from time to time in certain applications and historically used more in smaller networks**. To this point, it has been my belief up to this point that **DHCP is much more useful in larger settings**. For this reason, I was shocked to learn that **each of our near 3000 networking devices have painstakingly been allocated static management IP addresses**. It was explained that this was easier to handle that DHCP.
I will admit, the scheme for the addressing is nifty. The **second octet is the device-class/network identifier**, the **third octet is the building identifier** (we have some odd 200 buildings on campus), and the **fourth is the device identifier**.
So the scheme is understandable, but still seems like a lot of numbers to remember; imagine I am looking for a Xirrus array in say the Cafeteria on St. Phillip's Street. Yes DNS could solve this, but the IP's do sometimes get changed and that could result in a nightmare if one is changed and not the other.
The solution to me seems a DHCP/DNS combo.
So to sum up the question, **from a management standpoint, why is it a good idea to use Static or DHCP addressing on equipment?** | 2014/05/24 | [
"https://networkengineering.stackexchange.com/questions/8067",
"https://networkengineering.stackexchange.com",
"https://networkengineering.stackexchange.com/users/5785/"
] | I’ll keep this post about your situation specifically.
First and foremost, managing over 3,000 devices with static IP addresses is just plain foolish. DHCP is a well-known and established protocol that solves the tedious task of manually assigning and fixing manual IP addresses. If they are that concerned about making sure they have control over **every** IP address on their network, set them as DHCP reservations. Even from a security standpoint, you don’t stand to benefit *that* much from eliminating DHCP servers.
By sticking with this route, you will lose:
* **Change management capabilities**
* Customer insight
The big hitter on this list is change management capabilities. If you need to swap IPs around, you really don’t have a good way to do this; and that makes (or will make) your life arduous. If your teammates aren't on board with it and want to stick with their old ways, try to rope in your management and inform them of what a colossal waste of time it is.
Regarding your nifty IP scheme; you will still be able to maintain that; If anything, to a greater degree. [IPAM](https://networkengineering.stackexchange.com/questions/7250/what-is-ip-address-management-why-its-needed-how-does-the-vendors-like-bluec/7253#7253) gives you the capability to drill down into smaller and smaller subnet ranges, making it seemingly easy to implement in your case. This will allow you to cascade further and further down into the building/device class you desire. | I suppose it boils down to what you mean by *networking devices*. Routers, switches, firewalls, access points, etc., etc. do need to have fixed, known locations. It's a bad idea to rely on DHCP and DNS -- even where "sticky" addresses are used.
One network fault is all it takes to learn how bad an idea that is... say your network is broken *somewhere*. You (in fact, the entire engineering department) happen to be on the side that cannot reach DNS, and probably DHCP too. If all of your gear has random, unknown DHCP assigned addresses, you'll have no map, and no access to create one. If your workstation is portable, off, etc. *you* may not have an address from which to work. Various networking devices may start dropping off the network as their leases expire, other devices (like your laptop) coming online for the day won't have an address, rebooted equipment won't have addresses... A failure of the DHCP server will net a similar effect. A failure of the DNS server(s) will leave a mess of old, invalid registrations, and a bunch of holes where new registrations didn't happen -- nothing I know of will retry. |
78,220 | What is the meaning of "Raven" [phonetic] heard in use at Reagan National Airport? Most recently heard: The ATC will say "proceed direct raven" or "direct raven maintain" whatever altitude; or "direct raven; raven at 6,000." I've looked in every ATC/Pilot glossary I can find, but nothing. Have not heard at other airports, not even Dulles or BWI in the Washington metro area. A military pilot friend thinks it is an enroute, departure, approach or holding fix, which he says would be specific to one airport. Can anyone tell me exactly what we are hearing [an acronym?] and if this is the meaning? | 2020/05/18 | [
"https://aviation.stackexchange.com/questions/78220",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/49644/"
] | RAVNN (Pronounced Raven) is the name of a waypoint in Maryland. From the [FAA Fixes / Waypoints directory](https://www.faa.gov/air_traffic/flight_info/aeronav/aero_data/Loc_ID_Search/Fixes_Waypoints/)
>
> RAVNN MARYLAND BAL\*C\*174.00/22.98 OTT\*C\*070.89/12.17
> ENO\*C\*250.66/53.40 DCA\*D\*106.56 38-48-15.9900N 076-31-04.9100W
>
>
>
[38°48'15.9900N 76°31'04.9100W](https://www.google.com/maps/place/38%C2%B048'16.0%22N+76%C2%B031'04.9%22W/@38.8839843,-76.840121,11z/data=!4m5!3m4!1s0x0:0x0!8m2!3d38.8044417!4d-76.5180306)(Google Maps link) is east of Washington. | RAVNN is a waypoint on the RAVNN6 STAR ([page 1](http://aeronav.faa.gov/d-tpp/2005/00804RAVNN.PDF), [page 2](http://aeronav.faa.gov/d-tpp/2005/00804RAVNN.PDF)) for KBWI and surrounding airports, which is handled by Potomac Approach. |
78,220 | What is the meaning of "Raven" [phonetic] heard in use at Reagan National Airport? Most recently heard: The ATC will say "proceed direct raven" or "direct raven maintain" whatever altitude; or "direct raven; raven at 6,000." I've looked in every ATC/Pilot glossary I can find, but nothing. Have not heard at other airports, not even Dulles or BWI in the Washington metro area. A military pilot friend thinks it is an enroute, departure, approach or holding fix, which he says would be specific to one airport. Can anyone tell me exactly what we are hearing [an acronym?] and if this is the meaning? | 2020/05/18 | [
"https://aviation.stackexchange.com/questions/78220",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/49644/"
] | RAVNN (Pronounced Raven) is the name of a waypoint in Maryland. From the [FAA Fixes / Waypoints directory](https://www.faa.gov/air_traffic/flight_info/aeronav/aero_data/Loc_ID_Search/Fixes_Waypoints/)
>
> RAVNN MARYLAND BAL\*C\*174.00/22.98 OTT\*C\*070.89/12.17
> ENO\*C\*250.66/53.40 DCA\*D\*106.56 38-48-15.9900N 076-31-04.9100W
>
>
>
[38°48'15.9900N 76°31'04.9100W](https://www.google.com/maps/place/38%C2%B048'16.0%22N+76%C2%B031'04.9%22W/@38.8839843,-76.840121,11z/data=!4m5!3m4!1s0x0:0x0!8m2!3d38.8044417!4d-76.5180306)(Google Maps link) is east of Washington. | Generally, the idea is that a *waypoint* has a five letter or six letter code that is
* unique (within the region)
* easy to remember
* easy to pronounce as a word
* hard to confuse
In this case, the code of the waypoint is RAVNN, but it is pronounced "raven", because that is much faster to say, much easier to remember, and just as easy to understand as "Romeo Alpha Victor November November". The idea is that even if you've never been to the area before and have never heard the waypoint pronounced before, when the controller says "raven", you can immediately understand that she is talking about RAVNN. Imagine, the controller says "Romeo Alpha Victor November November" and you are looking at your approach plate and then try to remember "Wait, was it Romeo Alpha at the beginning or Alpha Romeo?"
Additionally, when there is a standard approach using multiple waypoints, the waypoints are sometimes chosen in such a way that they "tell a story", e.g. using words from a well-known children's rhyme, poem, song, proverb, quote, Bible verse, etc.
For example, a fictional approach could go along waypoints QUOTH RAVNN NVMOR or HAMLT TOBEE ORNOT or something like that. WEEEE WLLLL NEVVR FORGT SEP11 is a *real* one that actually exists, going into Washington. |
78,220 | What is the meaning of "Raven" [phonetic] heard in use at Reagan National Airport? Most recently heard: The ATC will say "proceed direct raven" or "direct raven maintain" whatever altitude; or "direct raven; raven at 6,000." I've looked in every ATC/Pilot glossary I can find, but nothing. Have not heard at other airports, not even Dulles or BWI in the Washington metro area. A military pilot friend thinks it is an enroute, departure, approach or holding fix, which he says would be specific to one airport. Can anyone tell me exactly what we are hearing [an acronym?] and if this is the meaning? | 2020/05/18 | [
"https://aviation.stackexchange.com/questions/78220",
"https://aviation.stackexchange.com",
"https://aviation.stackexchange.com/users/49644/"
] | RAVNN is a waypoint on the RAVNN6 STAR ([page 1](http://aeronav.faa.gov/d-tpp/2005/00804RAVNN.PDF), [page 2](http://aeronav.faa.gov/d-tpp/2005/00804RAVNN.PDF)) for KBWI and surrounding airports, which is handled by Potomac Approach. | Generally, the idea is that a *waypoint* has a five letter or six letter code that is
* unique (within the region)
* easy to remember
* easy to pronounce as a word
* hard to confuse
In this case, the code of the waypoint is RAVNN, but it is pronounced "raven", because that is much faster to say, much easier to remember, and just as easy to understand as "Romeo Alpha Victor November November". The idea is that even if you've never been to the area before and have never heard the waypoint pronounced before, when the controller says "raven", you can immediately understand that she is talking about RAVNN. Imagine, the controller says "Romeo Alpha Victor November November" and you are looking at your approach plate and then try to remember "Wait, was it Romeo Alpha at the beginning or Alpha Romeo?"
Additionally, when there is a standard approach using multiple waypoints, the waypoints are sometimes chosen in such a way that they "tell a story", e.g. using words from a well-known children's rhyme, poem, song, proverb, quote, Bible verse, etc.
For example, a fictional approach could go along waypoints QUOTH RAVNN NVMOR or HAMLT TOBEE ORNOT or something like that. WEEEE WLLLL NEVVR FORGT SEP11 is a *real* one that actually exists, going into Washington. |
186,086 | I am a Java (Web) Developer. Having knowledge about c#, PHP and Ruby. I am getting confused how to keep myself updated with very fast changing the programming language and their implementation.
Like, in the mobile, you can see around 7-8 OS. There are very much finer example of event-driven programming to make scalable application like node.js, Ember, Require etc.. Then WebSockets, Socket.io, HTML5.
Python and C once again climbing on the top. Scala and clojure are becoming very popular languages. Haskell and Erlang are also a great language too..
With so many programming language and platform, it is sometimes i feel very bad that i am missing some good things in my career.
I am just confused what to learn and how to co-op with this fast-changing world. Please suggest. | 2013/02/06 | [
"https://softwareengineering.stackexchange.com/questions/186086",
"https://softwareengineering.stackexchange.com",
"https://softwareengineering.stackexchange.com/users/80692/"
] | >
> *Like, in the mobile, you can see around 7-8 OS. There are very much finer example of event-driven programming to make scalable application
> like node.js, Ember, Require etc.. Then WebSockets, Socket.io, HTML5.*
>
>
>
**Try to be a master of one trade (the trade you works with), then try to be a jack of others**. How much you try to learn other things, there will always a sea of new technologies around you which you doesn't know. Don't get disheartened by thinking about what you doesn't know, but think about how good you are in the field you said you currently know. How much of a master you are in the technologies you know and working regularly.
>
> *With so many programming language and platform, it is sometimes i feel very bad that i am missing some good things in my career.*
>
>
>
True, especially when you see others excellent programmers gives exemplary answers (in forums like this/SO) which you cannot even think about. You kind of think, how on earth they acquire that knowledge. But there is no short cut, they made effort to study them, or happened to work on that technology. With more experience you will get more opportunities to work with other technologies.
>
> *I am just confused what to learn and how to co-op with this fast-changing world. Please suggest.*
>
>
>
Well, first make sure you are a master at field which you currently working. If you get more time to spent, then choose another language. Since you asked for suggestion and said you already know JAVA, just make an effort in Android. I said this because
1. Android uses JAVA
2. It is open source, takes no cost to setup.
3. From my understanding, you haven't worked in Mobility, which is
booming right now.
Well just some suggestions. | Perhaps you should do the selection by domain and not by technology/prog language?
What is it that is of interest to you? Databases? Mobile applications? Search? Natural language processing? Big Data (hot right now)? Graphics? Web apps all around? Domain-specific web apps (like social)? GIS? Distributed programming for applications like say, ejabberd for chat? Enterprise middleware? Systems programming? System administration software?
Once you select domain, technology choice becomes natural, e.g. mobile => Java/Android + IOS/Objective-C. (You also have some flexibility re choice of tech there, e.g Scripting Layer 4 Android is becoming popular among some people who like dynamic languages.)
I also second advice of Krishnabhadra on becoming a master in 1 or at most few subjects. |
18,737,718 | I have a screen with animation in my WPF application. I need the animation to run only onceper user session. This means that if a user sees the screen with the animation the first time, it would play, but when the user comes back to it it will be in its final state (skipped to end).
I have a boolean value in my ViewModel which holds all the users/sessions logic and it indicates weather or not the animation should run or it should be shown at its final frame.
How can i achieve this type of Binding / functionality only with XAML? | 2013/09/11 | [
"https://Stackoverflow.com/questions/18737718",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/1176547/"
] | Rake is a "[software task management tool](http://en.wikipedia.org/wiki/Rake_%28software%29)", similar to Make, etc. in other systems.
See: <http://guides.rubyonrails.org/command_line.html#rake>
>
> Rake is Ruby Make, a standalone Ruby utility that replaces the Unix utility 'make', and uses a 'Rakefile' and .rake files to build up a list of tasks. In Rails, Rake is used for common administration tasks, especially sophisticated ones that build off of each other.
>
>
> You can get a list of Rake tasks available to you, which will often depend on your current directory, by typing rake --tasks. Each task has a description, and should help you find the thing you need.
>
>
>
It is most often used for administration level tasks that can be scripted. The benefit to using Rake over Make or similar, is that it is a Ruby tool and can interface with your RoR app natively, so Models, data constraints and business rules are all available for use.
Rails comes with a set of predefined Rake tasks that allow you to perform database migrations, generate Rails scaffold files, etc. | Rake utility allows you to create a job/task which uses rails environment. So say, you want to count the votes a user has given to an article and save it somewhere. You write a rake job, in which you can use Rails models and other helpers and get it done without going away from Rails. |
174,542 | Why do games usually only allow some specific resolutions, instead of allowing arbitrary window resizing? Are there any technical difficulties for arbitrary window resizing? | 2019/08/11 | [
"https://gamedev.stackexchange.com/questions/174542",
"https://gamedev.stackexchange.com",
"https://gamedev.stackexchange.com/users/126344/"
] | There are plenty of games out there, some are from big studios, some use well established and battle tested tools, plenty don't. I can think of plenty of things that could go wrong when it comes to resolution.
*I am leaving aside the fact that on full-screen the monitor and driver combo will have a set of supported modes (and there is no point in emulating modes), and I am also leaving aside the fact that some platforms will force the resolution (some even handle the scaling).*
**Motivations for a minimum**:
* Some UI elements and spacing will just break if the window size is too small. Depending on you do your layout, you could end up computing negative sizes (e.g. position an element to leave a margin to the left and a margin to the right, and then there is no room for the element).
* Too small UI elements are bad accessibility. So you avoid your negative sizes by just scaling everything uniformly, now you can end up with too little space for texts, should you add a scroll bar? Tough luck, there is no room, gotta make that scroll bar tiny. ¡Arg! nobody can see it, let alone click it, and don't get me started on touch screens.
* Smaller resolution come with better performance. For a competitive game where responsiveness is an important consideration, having a resolution that is too small but performs better than the average could be seen as a form of cheating.
**Motivations for a maximum**:
* More pixels to draw is less performance. Although, granted, on a traditional pipeline the number of objects is the bottleneck.
* Your textures pixelate. You can have higher resolution textures – or if your engine allows, vector graphics – at a cost on performance.
* You have to worry about scaling up fonts. Will you allow more text on screen or use bigger text? The text could end up too small on the screen, because resolution and real screen size could change independently. This is an added difficulty.
* When it comes to a competitive game… similarly to how a small resolution could make things harder to click, a bigger resolution could make hit-boxes too easy. Assuming the developers are using a traditional pipeline with moderately sized textures and a limited number of objects on screen, the additional resolution has a small impact on performance… then the large hit-boxes are all win for the player, and thus an unfair advantage (over players with smaller screens) in the competitive game.
**Motivation to preserve aspect ratio**:
* You cannot just scale uniformly. If you choose to scale, you got to consider the aspect ratio to avoid distortions. The code is no big deal, but has consequences.
* Since you want to avoid distortions you will scale to match one axis (often the vertical), thus, a different aspect ration would mean that a player could see more of the world than another. Perhaps that is feature, perhaps that is an unfair advantage. Sounds like something to avoid if you hope to create an e-sport. Should you add black bars?
* That list view where the users picks whatever, it is perfect for some aspect ratios, on others it is a waste of space. On the list, unless you want distorted text, the text can only scale with the vertical, thus on a wide enough aspect ratio you are wasting a lot of space. Should it be a grid?
* How many columns should that grid have? We need to write code to determinate how many columns, considering the width of the text, with the added difficulty of keeping the columns the same width.
* You could flow elements instead. Now you need to figure out when to push an item to a new row. Advise: make all the elements the same size (perhaps by using an icon to represent them and dedicate a sidebar for the description of the selected item), so you do not have to deal with elements of different sizes. *Thankfully we get solutions to flow text in most environments, however, remember somebody had to solve that.*
**Motivations for discrete resolutions**:
* If you support only a discrete set of resolutions, you do not need code to decide how to flow or to compute number of columns. Why? Because you can solve and hard-code the solutions for a discrete number of cases.
* Not all layouts make sense. Going back to the problem of having a resolution that is too small, perhaps you could flow elements. That sidebar should be pushed to a footer if the resolution is too narrow. Do we want to handle that dynamically?
* It can be hard to convey to user where things are if they can move around.
Extra wrench: we should let the user scale up the text and the UI elements for accessibility. Yeah, plenty of games do not have that.
We effectively need modern browsers' CSS to deal with all of it with relative ease. However, most game engines and UI tool-kits designed to integrate with games don't have tools that are that powerful. If there aren't available for the platform & engine & language combo you use... It is much easier to support a discrete set of resolutions on which we can test the game, than to retrofit content flow on a UI solution that does not support it, or roll your own. *And even if you have a good UI toolkit, you still should have a minimum.*
This is particularly true if you do not have developers working exclusively on the UI. Arguably you should have them, if you can afford them. Can you? How many? Perhaps you should be placing resources in making a more entertaining and fun game, in particular if you are an indie developer or a small studio. *Unless the game is about resizing windows.*
The flip side is when we are a big studio, have developers working exclusively on the UI, and we are making an e-sport-ish competitive game. We do not want to give unfair advantages to players such as extra performance with small resolution, or extra field of view. Nor we want players taking advantage of high resolution for ease of aiming. | It’s already something of a chore to support multiple fixed window sizes and aspect ratios in terms of UI scaling, managing the visible play area (especially in some kinds competitive games), render target sizing and compositing, and so on. Just look around here at the number of questions focused on aspect ratio handling and scaling issues.
The added difficulty of an effectively infinite number of width / height combinations often doesn’t seem worth the effort as most of the time folks play games such that the game takes over the full real estate of the display.
More casual games, which may be played in non-full screen windowed mode more commonly tend to support it. But those casual games have found a more welcoming home on mobile platforms in the last decade, where it’s generally not possible to do arbitrary window sizes anyhow. |
37,388,805 | So I would like to only view certain pages in one explorer in google analytics how do i do so?
For example:
example.com/contact < (exact match and not anything beyond contact/example)
example.com/blog
example.com/how-to
I tried using segments with the conditions "exact matches" but what happen is that it still shows me all the pages that is not relevant to the above conditions when I view the segment on my behavior> site content> all pages.
And advance filtering limits to just "AND" even I tried using "matching regexp" with "/(contact|blog|how-to)" It still show everything after "/contact/example/example"
Any idea how to solve this issue? | 2016/05/23 | [
"https://Stackoverflow.com/questions/37388805",
"https://Stackoverflow.com",
"https://Stackoverflow.com/users/6370567/"
] | Try to conclude your regex with $ (/how-to$), meaning "ends with the preceding character. GA regex is a bit overeager and assumes you want to match anything that contains your string, so you have to specifically terminate with the [ends-with metacharacter](http://regexone.com/lesson/line_beginning_end). | Not that the end result in this particular case would yield anything different but I just think it is best practice escaping slashes also in regexes in Google Analytics too just in case the regex is copied and used somewhere else like Perl e.g.
Here is a shorter version:
>
> ^\/(contact|blog|how-to)$
>
>
> |
740 | The [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") [tag wiki description](https://pets.stackexchange.com/tags/travel/info) says it's for travelling *with* pets, but there are a few questions where the owner is travelling and wants to arrange holiday care for the pet.
Here are two that are currently tagged "travel" (I'm sure there are others where the owner is travelling that are *not* tagged "travel"): [How should I accomodate my cat if I travel for work?](https://pets.stackexchange.com/questions/2838/work-travel-and-a-cat), [Is there any way to make sure my bearded dragon has enough to eat while I'm on vacation?](https://pets.stackexchange.com/questions/1746/is-there-any-way-to-make-sure-my-bearded-dragon-has-enough-to-eat-while-im-on-v/1749#1749)
I went to change the tags on the questions but I couldn't find an alternative tag.
I see a few options here.
* Just remove the travel tag and don't bother about retagging (or just retag with something broader like [care](https://pets.stackexchange.com/questions/tagged/care "show questions tagged 'care'"))
* Remove the travel tag and create a suitable tag for arranging care of your pets whilst you're away
* Change the tag wiki description so that it also includes when *you* are travelling and leaving your pet behind.
I would lean towards one of the first two - I don't think that travelling with a pet and arranging care of your pet whilst you're away are close enough to warrant using the same tag. | 2014/04/09 | [
"https://pets.meta.stackexchange.com/questions/740",
"https://pets.meta.stackexchange.com",
"https://pets.meta.stackexchange.com/users/628/"
] | I think the wiki page for [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") should be updated. I think lumping those questions in with care is too generalized. It is a question about travelling and how to take care of your pet while travelling, only in these instances the owner and pet are separated from each other. | Okay, an answer is better than a comment, so that also downvoting is possible. This is for the question asked in question title alone.
Yes. The [care](https://pets.stackexchange.com/questions/tagged/care "show questions tagged 'care'") tag should be fit enough for use with such questions. |
740 | The [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") [tag wiki description](https://pets.stackexchange.com/tags/travel/info) says it's for travelling *with* pets, but there are a few questions where the owner is travelling and wants to arrange holiday care for the pet.
Here are two that are currently tagged "travel" (I'm sure there are others where the owner is travelling that are *not* tagged "travel"): [How should I accomodate my cat if I travel for work?](https://pets.stackexchange.com/questions/2838/work-travel-and-a-cat), [Is there any way to make sure my bearded dragon has enough to eat while I'm on vacation?](https://pets.stackexchange.com/questions/1746/is-there-any-way-to-make-sure-my-bearded-dragon-has-enough-to-eat-while-im-on-v/1749#1749)
I went to change the tags on the questions but I couldn't find an alternative tag.
I see a few options here.
* Just remove the travel tag and don't bother about retagging (or just retag with something broader like [care](https://pets.stackexchange.com/questions/tagged/care "show questions tagged 'care'"))
* Remove the travel tag and create a suitable tag for arranging care of your pets whilst you're away
* Change the tag wiki description so that it also includes when *you* are travelling and leaving your pet behind.
I would lean towards one of the first two - I don't think that travelling with a pet and arranging care of your pet whilst you're away are close enough to warrant using the same tag. | 2014/04/09 | [
"https://pets.meta.stackexchange.com/questions/740",
"https://pets.meta.stackexchange.com",
"https://pets.meta.stackexchange.com/users/628/"
] | I mostly agree with expanding the scope of the [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") tag as [suggested](https://pets.meta.stackexchange.com/a/742/101) by [Matt S.](https://pets.meta.stackexchange.com/users/481/matt-s), but I've also thought a couple of new tags might be useful:
* [pet-sitting](https://pets.stackexchange.com/questions/tagged/pet-sitting "show questions tagged 'pet-sitting'") for questions about having someone watch your pet while you're away, either in their home or yours.
* [boarding](https://pets.stackexchange.com/questions/tagged/boarding "show questions tagged 'boarding'") (with a synonym [kenneling](https://pets.stackexchange.com/questions/tagged/kenneling "show questions tagged 'kenneling'")) for questions about having pets stay at commercial facilities that specialize in caring for animals. This could probably also apply to questions about day-care facilities. | Okay, an answer is better than a comment, so that also downvoting is possible. This is for the question asked in question title alone.
Yes. The [care](https://pets.stackexchange.com/questions/tagged/care "show questions tagged 'care'") tag should be fit enough for use with such questions. |
740 | The [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") [tag wiki description](https://pets.stackexchange.com/tags/travel/info) says it's for travelling *with* pets, but there are a few questions where the owner is travelling and wants to arrange holiday care for the pet.
Here are two that are currently tagged "travel" (I'm sure there are others where the owner is travelling that are *not* tagged "travel"): [How should I accomodate my cat if I travel for work?](https://pets.stackexchange.com/questions/2838/work-travel-and-a-cat), [Is there any way to make sure my bearded dragon has enough to eat while I'm on vacation?](https://pets.stackexchange.com/questions/1746/is-there-any-way-to-make-sure-my-bearded-dragon-has-enough-to-eat-while-im-on-v/1749#1749)
I went to change the tags on the questions but I couldn't find an alternative tag.
I see a few options here.
* Just remove the travel tag and don't bother about retagging (or just retag with something broader like [care](https://pets.stackexchange.com/questions/tagged/care "show questions tagged 'care'"))
* Remove the travel tag and create a suitable tag for arranging care of your pets whilst you're away
* Change the tag wiki description so that it also includes when *you* are travelling and leaving your pet behind.
I would lean towards one of the first two - I don't think that travelling with a pet and arranging care of your pet whilst you're away are close enough to warrant using the same tag. | 2014/04/09 | [
"https://pets.meta.stackexchange.com/questions/740",
"https://pets.meta.stackexchange.com",
"https://pets.meta.stackexchange.com/users/628/"
] | I think the wiki page for [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") should be updated. I think lumping those questions in with care is too generalized. It is a question about travelling and how to take care of your pet while travelling, only in these instances the owner and pet are separated from each other. | How about a new tag [unsupervised](https://pets.stackexchange.com/questions/tagged/unsupervised "show questions tagged 'unsupervised'") ? |
740 | The [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") [tag wiki description](https://pets.stackexchange.com/tags/travel/info) says it's for travelling *with* pets, but there are a few questions where the owner is travelling and wants to arrange holiday care for the pet.
Here are two that are currently tagged "travel" (I'm sure there are others where the owner is travelling that are *not* tagged "travel"): [How should I accomodate my cat if I travel for work?](https://pets.stackexchange.com/questions/2838/work-travel-and-a-cat), [Is there any way to make sure my bearded dragon has enough to eat while I'm on vacation?](https://pets.stackexchange.com/questions/1746/is-there-any-way-to-make-sure-my-bearded-dragon-has-enough-to-eat-while-im-on-v/1749#1749)
I went to change the tags on the questions but I couldn't find an alternative tag.
I see a few options here.
* Just remove the travel tag and don't bother about retagging (or just retag with something broader like [care](https://pets.stackexchange.com/questions/tagged/care "show questions tagged 'care'"))
* Remove the travel tag and create a suitable tag for arranging care of your pets whilst you're away
* Change the tag wiki description so that it also includes when *you* are travelling and leaving your pet behind.
I would lean towards one of the first two - I don't think that travelling with a pet and arranging care of your pet whilst you're away are close enough to warrant using the same tag. | 2014/04/09 | [
"https://pets.meta.stackexchange.com/questions/740",
"https://pets.meta.stackexchange.com",
"https://pets.meta.stackexchange.com/users/628/"
] | I mostly agree with expanding the scope of the [travel](https://pets.stackexchange.com/questions/tagged/travel "show questions tagged 'travel'") tag as [suggested](https://pets.meta.stackexchange.com/a/742/101) by [Matt S.](https://pets.meta.stackexchange.com/users/481/matt-s), but I've also thought a couple of new tags might be useful:
* [pet-sitting](https://pets.stackexchange.com/questions/tagged/pet-sitting "show questions tagged 'pet-sitting'") for questions about having someone watch your pet while you're away, either in their home or yours.
* [boarding](https://pets.stackexchange.com/questions/tagged/boarding "show questions tagged 'boarding'") (with a synonym [kenneling](https://pets.stackexchange.com/questions/tagged/kenneling "show questions tagged 'kenneling'")) for questions about having pets stay at commercial facilities that specialize in caring for animals. This could probably also apply to questions about day-care facilities. | How about a new tag [unsupervised](https://pets.stackexchange.com/questions/tagged/unsupervised "show questions tagged 'unsupervised'") ? |
563,579 | I got a job to do a household appliances with wireless remote control. I’m working as embedded developer in current company, but we haven't had to certificate our solutions and I'm looking for advice.
The first level of this job is to make a prototype of the machine. However I want this prototype not to demand too many modifications during the certifications process before entering the EU market.
As for my internet research, I know that the necessery things to do are: certification EMC, RED, LVD and additionally norms IEC-60335 and IEC-60730 for Class-B machine (household appliances).
Has anyone of you designed or made a household device controled by MCU?
Is following norms IEC-60335 and IEC-60730 demanded? Are making the tests obligatory for the norms? Or only the producer statement is enough to let the product enter the market?
What documents are needed to conduct the test of this kind of appliances in external laboratory (PCB circuict schematic, list of norms, elements list, software architecture, code source, code/libraries certifications etc.)?
For Class-B device necessery is to use mechanisms self-test peripherals of MCU (such as CPU, RAM, Flash, Watchodgs etc.)?
But the producer of the chip (Nordic Semiconductor - nRF5) I chose doesnt provide the self-test library or the support for this kind of tests. Can I go through the certification process implementing this kind of self-test by my own or using for example only watchdogs?
For example, ST Electronics provides certified library of this type of self-test for free. However its wireless modules are more difficult to get and much more expensive than nRF modules.
I would like to use nRF modules because its precertified with FCC/IC etc.
And here I have another question: whether the certification of my own remote controller with precertified module on my own PCB circuit with battery (CR2032 3V3) supply and 4 buttons is as expensive as using a not precertified radio module?
**UPDATE:**
To precise: my goal is to designing and making a prototype a remotely controlled cooker hood. I have wanted to use RF modules in remote controller and mainboard cooker hood. The LED lights and turbine (low voltage 10V) would be controlled by the MCU. The voltage to mainboard would be provided by the 12V power supply.
As I found out the norm IEC-60730 divides the household devices in to 3 classes:
* Class A - Control functions, which are not intended to be relied upon for the safety of the equipment. Examples are: room thermostats, humidity controls, lighting controls, timers, and switches.
* Class B - Control functions, which are intended to prevent unsafe operation of the controlled equipment. Examples are: thermal cut-offs and door locks for laundry equipment.
* Class C - Control functions, which are intended to prevent special hazards (e.g., explosion of the controlled equipment). Examples are: automatic burner controls and thermal cut-outs for closed, un-vented water heater systems.
[https://www.nxp.com/docs/en/application-note/AN3257.pdf]
Theoretically it would be possible to define that control as Class A - lightning control, timers and switches. It would make the process of designing easier, because the software systems of safety aren't demanded in this class. Unfortunately the control of a turbine makes this project as device of class B.
Thank you for your answers, I hope they would be useful to others in the future, because the subjects of meeting the standards, safety regulations, certification of products and the right way of conducting the project are not well described on the internet and this is the next step after the own DIY projects. | 2021/05/05 | [
"https://electronics.stackexchange.com/questions/563579",
"https://electronics.stackexchange.com",
"https://electronics.stackexchange.com/users/284772/"
] | The detailed technical information on your product would be needed to advise on exactly what standards may or may not be applicable. But I can talk in general terms.
>
> I know that the necessery things to do are: certification EMC, RED,
> LVD...
>
>
>
This is not anywhere near as simple, you also need to declare compliance with the correct parts of each. For example, you cannot declare compliance with the safety parts of the LVD if you need to declare compliance with RED.
I would strongly advise getting consultancy from a test house (or a dedicated compliance consultant), they are usually very helpful.
I would also look at the Declarations of Conformity from other similar products already in the market. This will give you an idea of what standards you *may* have have to declare conformity against (a test house will always tell you that what you need is more tests, having an idea of what may possibly be required will allow you to ask intelligent questions).
>
> Are making the tests obligatory for the norms? Or only the producer
> statement is enough to let the product enter the market?
>
>
>
Technically, yes. You can self-declare compliance with only a Technical File.
I can't emphasise enough that I think this would be an **extremely bad idea**, as you don't seem to have the knowledge required.
One of the possible things that can happen if you are found to be non-compliant in the market is forcible recall from customers at your cost. These regulations have teeth and can bankrupt companies.
>
> whether the certification of my own remote controller with
> precertified module on my own PCB circuit with battery (CR2032 3V3)
> supply and 4 buttons is as expensive as using a not precertified radio
> module?
>
>
>
It should be the same price, the same tests need to be made. The advantage is that you have a good chance of passing emissions with a pre-certified module. It is one less, major, uncertainty in your compliance process. | >
> Has anyone of you designed or made a household device controled by MCU?
>
>
>
Not as such, but industrial applications with very similar requirements. IEC 60730 is one of the "functional safety" ("SIL") standards, there exist different ones but all of them are pretty much the offspring of the industrial IEC 61508 functional safety standard.
I can't tell you if IEC 60730 compliance is required by law for your particular application. There's usually product-specific standards stating such. If it is then you'll need help from a test house, preferably at *design stage* of the product. These standards are complex and incredibly time consuming, which in turn makes them expensive, with lots of consultant hours. Some rule of thumb is that the cost and time to market are both multiplied by at least x3. In worst case maybe ten times the time & cost.
>
> What documents are needed to conduct the test of this kind of appliances in external laboratory (PCB circuict schematic, list of norms, elements list, software architecture, code source, code/libraries certifications etc.)?
>
>
>
For 60730 you'll need to demonstate compliance to every part of the document. This includes your quality system, your documentation, your hardware design, your MCU and your software design. All depending on what safety level of the standard that is required. You will likely have to use a safety MCU, I'd recommend checking out NXP parts (I'm not affiliated) since they are big in this area.
As for software, it likely means MISRA-C plus misc other functional safety practices. I wrote a little check list [here](https://stackoverflow.com/a/36892379/584518) which sums up the most common requirements. MISRA-C is a major undertaking too if you have never worked with it and have no C programming veterans (10+ years of C experience) in the company.
>
> For Class-B device necessery is to use mechanisms self-test peripherals of MCU (such as CPU, RAM, Flash, Watchodgs etc.)?
>
>
>
From what I vaguely recall from checking out that standard at some point, then yes. You need lots of self tests in the MCU hardware. ECC memory also helps a lot, since implementing flash CRCs is complex and a pain in general. Why picking a MCU with all this baked in is pretty much mandatory, re-inventing the wheel is a very bad idea here.
Another important thing to be aware of is that the functional safety standards are roughly 50% utter nonsense and 50% really good stuff. The key is to figure out which... You can usually argue about various nonsensical requirements in your compliance documentation. Test houses usually *don't* have very specific technical expertise of these requirements either and it is them that you have to convince. You can do this by using the same methodology as the safety standards themselves, [here is an example](https://stackoverflow.com/a/34950753/584518) where I make an argument against some nonsense NASA software rule by applying "FMEA" (which safety people love).
EMC/RED/FCC/IC etc testing will be a breeze compared to functional safety. I wouldn't worry as much about picking some part just because it has pre-certified radio. If you have a requirement for IEC 60730 then that's your main concern and everything else is secondary. It's far easier to manually make some radio compliant to a standard, though I guess that depends on what competence you have in house.
Yet another thing that might be a major pain in the neck is electrical safety testing for LVD/UL, in case that applies to your product. |
110,870 | In chapter 80, *The Primary*, Neal Stephenson has one of his character describe how the drives of a computer carried through a door (by the police, who where raiding the facility) will have been erased.
Basically, there's an enormous electromagnet around the door frame:
>
> Cantrell is now drawing an elaborate diagram, and has even slowed down, almost to a stop, the better to draw it. It begins with a tall rectangle. Set within that is a parallelogram, the same size, but skewed a little bit downwards, and with a little circle drawn in the middle of one edge. Randy realizes he’s looking at a perspective view of a door-frame with its door hanging slightly ajar, the little circle being its knob. *STEEL FRAME*, Cantrell writes, *hollow metal channels*. Quick meandering scribbles suggest the matrix of wall surrounding it, and the floor underneath. Where the uprights of the doorframe are planted in the floor, Cantrell draws small, carefully foreshortened circles. *Holes in the floor*. Then he encircles the doorframe in a continuous hoop, beginning at one of those circles and climbing up one side of the doorframe, across the top, down the other side, through the other hole in the floor, and then horizontally beneath the door, then up through the first hole again, completing the loop. He draws one or two careful iterations of this and then numerous sloppy ones until the whole thing is surrounded in a vague, elongated tornado. *Many turns of fine wire*. Finally he draws two leads away from this huge door-sized coil and connects them to a sandwich of alternating long and short horizontal lines, which Randy recognizes as the symbol for a battery. The diagram is completed with a huge arrow drawn vigorously through the center of the doorway, like an airborne battering ram, labeled B which means a magnetic field. *Ordo computer room door*.
>
>
> "Wow," Randy says. Cantrell has drawn a classic elementary-school electromagnet, the kind of thing young Randy made by winding a wire around a nail and hooking it up to a lantern battery. Except that this one is wound around the outside of a doorframe and, Randy guesses, hidden inside the walls and beneath the floor so that no one would know it was there unless they tore the building apart. Magnetic fields are the styli of the modern world, they are what writes bits onto disks, or wipes them away. The read/write heads of Tombstone’s hard drive are exactly the same thing, but a lot smaller. If they are fine-pointed draftsman’s pens, then what Cantrell’s drawn here is a firehose spraying India ink. It probably would have no effect on a disk drive that was a few meters away from it, but anything that was actually carried through that doorway would be wiped clean. Between the pulse-gun fired into the building from outside (destroying every chip within range) and this doorframe hack (losing every bit on every disk) the Ordo raid must have been purely a scrap-hauling run for whoever organized it – Andrew Loeb or (according to the Secret Admirers) Attorney General Comstock’s sinister Fed forces who were using Andy as a cat’s paw. The only thing that would have made it through that doorway intact would have been information stored on CD-ROM or other nonmagnetic media, and Tombstone had none of that.
>
>
>
Would this actually work? | 2014/05/01 | [
"https://physics.stackexchange.com/questions/110870",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/45702/"
] | There's really two parts to your question, which I'm going to answer separately. First of all, the explicit question:
Could a huge electromagnetic coil erase a hard drive carried through it?
------------------------------------------------------------------------
Sure it could. That's pretty much what a [degausser](http://degaussers.eu/what-is-a-degausser.asp) does, and these things are routinely used to erase magnetic media, including hard drives.
OK, with that out of the way, let's move on to the *implied* question:
Could you actually do that, without the person carrying the drive noticing?
---------------------------------------------------------------------------
Based on some quick research, my conclusion is: **no way in hell.**
To quickly and reliably degauss a hard drive, you [apparently need](http://whitakerbrothers.hubpages.com/hub/degaussing-machines) a magnetic field strength on the order of 15,000 Gauss (= 1.5 Tesla). Even if we assume that the Ordo hard drives were old and maybe specifically selected for low coercivity, we're still talking several thousand Gauss *at least*.
[For comparison](//en.wikipedia.org/wiki/Orders_of_magnitude_%28magnetic_field%29), the field strength inside a typical [MRI scanner](//en.wikipedia.org/wiki/Magnetic_resonance_imaging) is also around 1.5 Tesla, while the field *at the surface* of a modern [neodymium–iron–boron (Nd2Fe14B) rare earth magnet](//en.wikipedia.org/wiki/Neodymium_magnet) — basically, the strongest permanent magnet you can get — is around 1.25 Tesla.
Thus, someone walking through Stephenson's "degausser door" with a bunch of hard drives would experience something similar as if they tried carrying them through an MRI coil — or holding them while standing right next to a humongous door-sized Nd2Fe14B magnet slab.
Now, if you've ever played with neodymium magnets, you'll know that even tiny ones are damn hard to pry off any ferromagnetic objects they touch. To quote the Wikipedia page I linked to above:
>
> "Neodymium magnets larger than a few cubic centimeters are strong enough to cause injuries to body parts pinched between two magnets, or a magnet and a metal surface, even causing broken bones."
>
>
>
As for MRI scanners, there's a reason why the first *and* last thing they check, when you go and have an MRI scan, is that you have nothing potentially ferromagnetic on or *in* your body. The reason is that *anything* ferromagnetic that gets too close to an active MRI magnet is likely the get torn off your hands and violently slammed against the magnet. This [has been known to happen](http://www.wired.co.uk/magazine/archive/2010/09/start/mri-fatal-attraction) to pretty much any wholly or partially ferromagnetic object you'd care to imagine, from [wheelchairs](http://www.dailyecho.co.uk/news/9555780.Wheelchair_flung_across_room_by_MRI_scanner_s_magnets/), [office chairs](//www.youtube.com/watch?v=4uzJPpC4Wuk) and [floor polishers](http://web.archive.org/web/20110423211334/http://mrimetaldetector.com/blog/tag/floor-polisher/) to [scissors](http://web.archive.org/web/20120303154714/http://mrimetaldetector.com/blog/2010/07/not-magnet-safe-scissors/), [oxygen bottles](http://abcnews.go.com/US/story?id=92745) (which killed a small child) and even [pistols](http://www.thefirearmblog.com/blog/2010/01/03/dont-bring-a-gun-near-an-mri/) (which, yes, went off when it hit the scanner).
So, let's imagine what'll happen to your hapless policeman, as he's walking towards the magnetized door carrying a stack of hard drives. The first thing he's likely to notice, while still several meters away, is that something's pulling at the drives he's carrying (since they have a lot of ferromagnetic metal in the casing, and even some pretty strong magnets inside). If he's not careful, the drives might slip out of his hands and fly through the air towards the door, slamming against the door jamb with enormous force (and, yes, likely getting pretty well wiped in the process).
The next thing he might notice, if that's not enough to make him stay well away from the door, is that the same force is also tugging at his badge, gun, zipper, belt buckle, the screwdriver in his pocket that he used to open the servers and extract the hard drives, and anything else metallic that he might have on him. If he's not careful, and keeps approaching the door, those items might either get pulled out of his pockets, or they might simply get drawn to the door and *pull him along* with them. If he's lucky, the only thing getting pinched between the door and the objects is his clothing. If he's not...
Of course, that's all assuming that, when the magnet turned on, it didn't immediately turn any nearby chairs, tables, computer equipment and miscellaneous office supplies into [flying missiles](http://www.falckproductions.com/resouces/mri-safety/mri-hazards-missile-effect-electronics-and-implants/), with potentially lethal consequences to anyone standing between such an object and the door. Or that the intense magnetic field didn't simply mess up the unlucky officer's [pacemaker](http://www.mayoclinic.org/medical-professionals/clinical-updates/cardiovascular/new-protocols-allow-mri-selected-pacemaker-patients), as it would surely do to any cell phones or other electronic equipment they might be carrying. | **Possibly**.
[Degaussing](http://www.dataerasure.com/degauss.php) is the process of destroying data on a hard drive using an electromagnetic field, so there's some scientific basis to the idea. Assuming the electromagnet was sufficiently strong and there was no or very little shielding around the hard drive - which, if you were building a large electromagnet around a doorway specifically for this purpose, you could make sure was the case - then it could in theory be used to destroy a standard hard disk drive.
There'd be no *guarantee* that all of the data would be destroyed, the drive would almost certainly be unusable afterwards, and you couldn't ever switch to solid state drives. |
110,870 | In chapter 80, *The Primary*, Neal Stephenson has one of his character describe how the drives of a computer carried through a door (by the police, who where raiding the facility) will have been erased.
Basically, there's an enormous electromagnet around the door frame:
>
> Cantrell is now drawing an elaborate diagram, and has even slowed down, almost to a stop, the better to draw it. It begins with a tall rectangle. Set within that is a parallelogram, the same size, but skewed a little bit downwards, and with a little circle drawn in the middle of one edge. Randy realizes he’s looking at a perspective view of a door-frame with its door hanging slightly ajar, the little circle being its knob. *STEEL FRAME*, Cantrell writes, *hollow metal channels*. Quick meandering scribbles suggest the matrix of wall surrounding it, and the floor underneath. Where the uprights of the doorframe are planted in the floor, Cantrell draws small, carefully foreshortened circles. *Holes in the floor*. Then he encircles the doorframe in a continuous hoop, beginning at one of those circles and climbing up one side of the doorframe, across the top, down the other side, through the other hole in the floor, and then horizontally beneath the door, then up through the first hole again, completing the loop. He draws one or two careful iterations of this and then numerous sloppy ones until the whole thing is surrounded in a vague, elongated tornado. *Many turns of fine wire*. Finally he draws two leads away from this huge door-sized coil and connects them to a sandwich of alternating long and short horizontal lines, which Randy recognizes as the symbol for a battery. The diagram is completed with a huge arrow drawn vigorously through the center of the doorway, like an airborne battering ram, labeled B which means a magnetic field. *Ordo computer room door*.
>
>
> "Wow," Randy says. Cantrell has drawn a classic elementary-school electromagnet, the kind of thing young Randy made by winding a wire around a nail and hooking it up to a lantern battery. Except that this one is wound around the outside of a doorframe and, Randy guesses, hidden inside the walls and beneath the floor so that no one would know it was there unless they tore the building apart. Magnetic fields are the styli of the modern world, they are what writes bits onto disks, or wipes them away. The read/write heads of Tombstone’s hard drive are exactly the same thing, but a lot smaller. If they are fine-pointed draftsman’s pens, then what Cantrell’s drawn here is a firehose spraying India ink. It probably would have no effect on a disk drive that was a few meters away from it, but anything that was actually carried through that doorway would be wiped clean. Between the pulse-gun fired into the building from outside (destroying every chip within range) and this doorframe hack (losing every bit on every disk) the Ordo raid must have been purely a scrap-hauling run for whoever organized it – Andrew Loeb or (according to the Secret Admirers) Attorney General Comstock’s sinister Fed forces who were using Andy as a cat’s paw. The only thing that would have made it through that doorway intact would have been information stored on CD-ROM or other nonmagnetic media, and Tombstone had none of that.
>
>
>
Would this actually work? | 2014/05/01 | [
"https://physics.stackexchange.com/questions/110870",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/45702/"
] | **Possibly**.
[Degaussing](http://www.dataerasure.com/degauss.php) is the process of destroying data on a hard drive using an electromagnetic field, so there's some scientific basis to the idea. Assuming the electromagnet was sufficiently strong and there was no or very little shielding around the hard drive - which, if you were building a large electromagnet around a doorway specifically for this purpose, you could make sure was the case - then it could in theory be used to destroy a standard hard disk drive.
There'd be no *guarantee* that all of the data would be destroyed, the drive would almost certainly be unusable afterwards, and you couldn't ever switch to solid state drives. | I agree that **some** hard drives could be "erased" with the described electromagnet. However, if the hard drive is "magnetically shielded," then it is highly unlikely. If a "high enough" (> 50,000 hertz) frequency is used, the presence of the electromagnet should not be "humanly" detectable. |
110,870 | In chapter 80, *The Primary*, Neal Stephenson has one of his character describe how the drives of a computer carried through a door (by the police, who where raiding the facility) will have been erased.
Basically, there's an enormous electromagnet around the door frame:
>
> Cantrell is now drawing an elaborate diagram, and has even slowed down, almost to a stop, the better to draw it. It begins with a tall rectangle. Set within that is a parallelogram, the same size, but skewed a little bit downwards, and with a little circle drawn in the middle of one edge. Randy realizes he’s looking at a perspective view of a door-frame with its door hanging slightly ajar, the little circle being its knob. *STEEL FRAME*, Cantrell writes, *hollow metal channels*. Quick meandering scribbles suggest the matrix of wall surrounding it, and the floor underneath. Where the uprights of the doorframe are planted in the floor, Cantrell draws small, carefully foreshortened circles. *Holes in the floor*. Then he encircles the doorframe in a continuous hoop, beginning at one of those circles and climbing up one side of the doorframe, across the top, down the other side, through the other hole in the floor, and then horizontally beneath the door, then up through the first hole again, completing the loop. He draws one or two careful iterations of this and then numerous sloppy ones until the whole thing is surrounded in a vague, elongated tornado. *Many turns of fine wire*. Finally he draws two leads away from this huge door-sized coil and connects them to a sandwich of alternating long and short horizontal lines, which Randy recognizes as the symbol for a battery. The diagram is completed with a huge arrow drawn vigorously through the center of the doorway, like an airborne battering ram, labeled B which means a magnetic field. *Ordo computer room door*.
>
>
> "Wow," Randy says. Cantrell has drawn a classic elementary-school electromagnet, the kind of thing young Randy made by winding a wire around a nail and hooking it up to a lantern battery. Except that this one is wound around the outside of a doorframe and, Randy guesses, hidden inside the walls and beneath the floor so that no one would know it was there unless they tore the building apart. Magnetic fields are the styli of the modern world, they are what writes bits onto disks, or wipes them away. The read/write heads of Tombstone’s hard drive are exactly the same thing, but a lot smaller. If they are fine-pointed draftsman’s pens, then what Cantrell’s drawn here is a firehose spraying India ink. It probably would have no effect on a disk drive that was a few meters away from it, but anything that was actually carried through that doorway would be wiped clean. Between the pulse-gun fired into the building from outside (destroying every chip within range) and this doorframe hack (losing every bit on every disk) the Ordo raid must have been purely a scrap-hauling run for whoever organized it – Andrew Loeb or (according to the Secret Admirers) Attorney General Comstock’s sinister Fed forces who were using Andy as a cat’s paw. The only thing that would have made it through that doorway intact would have been information stored on CD-ROM or other nonmagnetic media, and Tombstone had none of that.
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Would this actually work? | 2014/05/01 | [
"https://physics.stackexchange.com/questions/110870",
"https://physics.stackexchange.com",
"https://physics.stackexchange.com/users/45702/"
] | Yes.
It is definitely possible to erase a hard drive with a strong enough magnetic field. Machines called "degaussers" exist only to erase hard drives in this manner, specifically without removing the drive platters (disks) from an enclosure.
Most degaussers appear to be rated at 8000-10000 Gauss. At the top end, then, degausser can produce a flux density (AKA field strength) of 1 Tesla - or about the same as in a loudspeaker ([thanks, Wikipedia!](http://en.wikipedia.org/wiki/Orders_of_magnitude_%28magnetic_field%29)). By comparison, this averages to about half that of typical MRI scanners.
So, yes it would be possible. The possible side-effects in the vicinity might be interesting, it may be that it would have been obvious to the officers raiding the building. | I agree that **some** hard drives could be "erased" with the described electromagnet. However, if the hard drive is "magnetically shielded," then it is highly unlikely. If a "high enough" (> 50,000 hertz) frequency is used, the presence of the electromagnet should not be "humanly" detectable. |
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