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I have used a cheap multimeter to measure voltages in simple DC circuits, but I have seen pictures of them plugged straight into the mains and used to measure various home-built generators.
Why doesn't the higher voltage fry the multimeter, and also in theory could a small cheapo multimeter be safely used to measure v... | #### <strong>WARNING</strong>: Note that <strong>some cheap meters are not suitable for use with 230 VAC AC mains.</strong> Some meters may have AC voltage ranges able to conceptually measure to well above AC mains voltage BUT have internal componentry not certified, suitable or safe at eg 230 VAC. <strong>Use of such ... |
The campus where I work has a long covered walkway (~.5 mile) which has several labeled pipes running under the roof (chilled water, fuel oil, air...). All of the pipes run dead straight <em>except</em> for the natural gas lines, which have little loops spaced about every 250ft, as seen in the attached image (the lower... | #### If the other pipes are carrying liquids with a greater specific heat coefficient then they would not be expected to experience the same temperature ranges, i.e. the water pipes will be at some average of the outside temp and the water temp.
A low-pressure gas line would be made of lighter material and the gas ins... |
For Newtonian fluids, the sinking (or rising) speed of a particle is (reasonably) well known. What is a relationship for shear thinning fluids?
| #### Doing a brief review of the literature, for spherical particles at high Reynolds numbers, <a href="http://books.google.com/books?id=ekIrBgAAQBAJ&lpg=PP1&ots=T2jDGPKMHP&lr&pg=PA87#v=onepage&q&f=false" rel="nofollow">it appears that you can use standard drag curves</a> to get the drag coeffic... |
NIL (Nanoimprint lithography) and hot embossing seem to mean the same thing in many instances. Is hot embossing a subset technique of NIL? Or are they completely different methods?
| #### I had the same question recently and was doing some research a wile ago. Sorry that I don't have all the literature prepared.
NIL is for very small structures, the mold is created with a lithography process. Depth are usually not very large. Can be very fast implemented in R2R. There are two basic types:
<... |
If I know the tensile strength of a pin, how do I compute the total strength of multiple pins? That is, 2 objects are connected by multiple pins, evenly distributed, each with a height of $2mm$ and a cross sectional area of $3.33mm^2$. For some reason the answer of just multiplying the tensile strength of each pin by... | #### The short answer is yes, it is that simple.
Think about it this way. The pins are connected to end plates of a given area. If all we're worried about is the tensile strength, we can place a one dimensional force on each end plate to put the system in pure tension. Now, split the system into a couple parts and do... |
I'm writing a presentation for people and I need an analogy to convey the following problem:
<blockquote>
Person A wants to sell a liquid, so he fills a tank, measures volume
and sends to Person B. Now Person B receives the liquid and wants to
know if he received the volume he bought from Person A, so since this... | #### I'm not sure of the specifics of your problem, it seems to be relatively straightforward to me. I have previoulsy considered addressing the subject of measurement errors with schoolchildren in the following manner - it may be of help to you and your audience or change in subject may confuse and distract them from ... |
Movable span bridges (<a href="http://en.wikipedia.org/wiki/Bascule_bridge">bascule</a> and <a href="http://en.wikipedia.org/wiki/Vertical-lift_bridge">lift</a>) typically employ a counterweight to help reduce the amount of energy and size of motor required to move the span. Due to variations in the the construction of... | #### This <a href="https://heavymovablestructures.org/assets/technical_papers/64.pdf" rel="noreferrer">paper</a> from the <a href="https://heavymovablestructures.org" rel="noreferrer">Heavy Movable Structures</a> group goes into detail about how roadway movable spans are balanced. It references AASHTO (<a href="http://... |
I've attempted to answer the following question and I need to know if I am on the right track:
<blockquote>
<strong>LOGIC GATES</strong>
Question 3
A manufacturing plant uses two tanks to store certain liquid chemicals
that are required in a manufacturing process. Each tank has a sensor
that detects wh... | #### So let's break this down, piece by piece.
<blockquote>
The output must only show LOW when BOTH inputs are LOW.
</blockquote>
We also know that the sensors read High (5V) when the tank volume is above 25%.
<pre>
| Tank 1 | Tank 2 | Monitor LED |
|--------|--------|-------------|
| High | High | Lit ... |
In <a href="https://engineering.stackexchange.com/questions/591/how-do-i-compute-combined-tensile-strength">this question about combined tensile strength</a>, all of the tensile bars are of the same material. But what if the case that they are made of different materials?
Say we have $200$ bars of $A=10 (\rm mm^2)$.
... | #### <a href="https://engineering.stackexchange.com/a/592/41">My answer</a> of that question covers this a little bit, and the link fully explains it, but I can go into more detail so you don't have to wade through that giant PDF. I'll link it again here at the bottom, because I'm going to reference equations in it for... |
I have a uniform load applied to the underside of a plastic sheet which is to be resisted by the combination of a bolt, washer, and nut as depicted below (the other end of the bolt is secured and will not budge).
<img src="https://i.stack.imgur.com/B5unK.png" alt="Diagram of nut, bolt, washer, and ASA plastic.">
The... | #### You are KIND OF RIGHT !
IN THIN PLASTIC DEFORMATION ONLY
OD of steel washer = OD
Thickness of Material (Pastic) = Tp
Shear Area = (OD+2.5*Tp)*pi()*Tp
Shear force is Shear Area * MPa = KN force.
The plastic deformation forms a "bulb" effect same goes for concrete piles
in the ground ! the diameter x 2.5 is th... |
My understanding is that cavitation occurs in the flow of a liquid when the static pressure drops below the vapor pressure, even intermittently. So even if the <em>time-averaged</em> static pressure (what you might measure) is above the vapor pressure, the pressure fluctuations from turbulence or other unsteadiness cou... | #### <strong>The difference between the two equations</strong>
The cavitation number is the ratio of the static pressure difference to the dynamic pressure difference. So, if you want to use the first equation, you would need to take the pressure using a Pitot tube to measure the total pressure, whereas if you want ... |
A friend of mine is a structural engineer and he often complains to me about how little sleep he gets at night worrying over whether or not he accounted for all the little details involved in his design.
For all the double and triple checking one might do, buildings are very complicated structures. Sometimes its im... | #### Air's answer is pretty thorough already, and the liability issue is truly complex. In my liability training at work, we've been told of situations where engineers from every firm with any association to the machinery or structure in question are named in suits, not necessarily because they're all at fault, but (1)... |
<a href="https://en.wikipedia.org/wiki/Maglev">Magnetic levitation</a> systems of transportation such as trains seem to be commonplace in early 2000's science fiction, and while some systems exist currently, they aren't exactly common.
It seems to me that this technology has grown unpopular (or at least has fallen int... | #### For a given method of transport to become the most popular, it needs to be the safest, cheapest, most efficient way to get from point A to point B, relative to comparable forms of transportation. In this case, the comparable transportation method is to use normal trains, which run on coal, electricity, etc.
Let's... |
I've recently been learning about FET amplifier circuits and I'm looking for some information that can help explain why the calculated and simulated Gain Values can differ by up to 15% in some cases.
this image is an example of the first FET amp.
<a href="http://www.electronics-tutorials.ws/amplifier/amp14.gif" rel="... | #### If you measure the gain, there is usually some variability in the measurements. This means that you would have to measure enough times to get a statistic distribution for the gain. The computed value should be equal to the mean of the distribution.
What I'm also curious about: is the gain given in Decibels (dB)? ... |
I've always wondered why refrigerators don't have some of their parts located outdoors like an air conditioner.
In warm weather, it seems like it would make sense to have the condenser outside like an AC unit to avoid heating the room. In cold weather, it seems like it would be much more efficient to have the condense... | #### In the winter, you're paying to run the refrigerator when you shouldn't need to run it at all. However, since we're also paying for heat and the refrigerator is generating heat then our furnace doesn't run as much and it doesn't make much difference.
In the summer, we're paying to cool our homes and the heat from ... |
I was recently reading up on the <a href="http://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse" rel="noreferrer">1981 Hyatt Regency walkway collapse</a>. It was a tragic loss of life and haunts many to this day.
The linked article does a better job of summarizing things, but here's a summarized version of wh... | #### At the time , my understanding was that high strength ,quench and tempered rods were specified . The contractor used hardware store threaded rod with less than half the strength without the engineers approval.
|
I am working on an idea that involves a jet engine, but I don't quite know how the fuel system works. In a combustion engine like that in a car, you have nozzles that spray the fuel into the piston chambers (I think, correct me if I am mistaken), and then it's ignited when the piston compresses the chamber (sometimes u... | #### The place where air and fuel are mixed is the <strong><a href="https://en.wikipedia.org/wiki/Combustor" rel="nofollow">combustor</a></strong>, also known as the <strong>flame holder</strong>:
<a href="https://upload.wikimedia.org/wikipedia/commons/1/1c/Combustor_diagram_componentsPNG.png" rel="nofollow"><img src="... |
I'm trying to construct a stainless steel high pressure containment vessel (pressure reactor) (2000 psi or so). Yes I realize that this is a don't try this at home type of thing, and I plan to put some lexan in front of it before I do any testing.
I'm looking at 2" stainless pipe with a wall thickness of .148"(rated ... | #### Use Flange & Blind Flange ANSI 2"-2500# WNRTJ ASME B16.5 A-182 F304. With a gasket RTJ SS304 and bolting.
|
This is inspired by the discussion and controversy surrounding the <a href="https://en.wikipedia.org/wiki/Keystone_Pipeline" rel="nofollow">Keystone Pipeline</a>.
The main part of the Keystone Pipeline system is about 3,400 kilometers long, stretching across a large portion of the United States. The Keystone XL extens... | #### Same as gas or water,etc, pipelines ; As long as someone is willing to pay for the construction. Presumably because they can profit by delivering the oil/gas/products to a destination. Other comments refer to the "nuts and bolts" of design and construction.
|
I have a chicken coop I plan on modifying to automatically open and close the door at dawn and dusk.
What sort of actuator or mechanism would be appropriate for operating the small, side-hinged door?
Constant power is not available (solar) plus it needs enough holding force to keep foxes out.
| #### You could build something out yourself and connect to a lead-acid battery which charged during the day like this one <a href="http://makeitbreakitfixit.com/2016/08/30/diy-home-automation-chicken-enclosure/" rel="nofollow noreferrer">http://makeitbreakitfixit.com/2016/08/30/diy-home-automation-chicken-enclosure/</a... |
Suppose I have a sealed enclosure, say <a href="http://www.hoffmanonline.com/product_catalog/catalog_item_detail.aspx?cat_1=34&cat_2=2346&cat_3=78347&catIDs=78347,186&itemIDs=3239,4185&catalog_item=4185" rel="nofollow">this one from Hoffman</a>:
The box is 16"x12"x6", made of galvanized steel with ... | #### <a href="http://www.automationdirect.com/static/specs/encstratusheatexchangers.pdf" rel="nofollow">http://www.automationdirect.com/static/specs/encstratusheatexchangers.pdf</a>
According to this document, heat load transfer through the walls of a metal enclosure is estimated in BTU/H as 1.25 x surface area (sq ft... |
My car has ultrasonic proximity sensors to help me park. I've noticed that when motorcycles whiz past me the proximity alarm goes off. I originally thought that the motorcycles were just too close, but now I have observed that that isn't the case; cars or other road users at a similar distance and speed do not set off ... | #### It is likely that the noise of the motorcycle is causing the sensor to activate.
This <a href="http://static.catalogs.rockwellautomation.com/pub-files/13676018925183f2e400f4c/pub/Ultrasonic-Sensing/Of/page.pdf" rel="nofollow">listing</a> of the advantages and disadvantages of ultrasonic sensors lists one of the d... |
Bridges are designed for the loads that come from the vehicles that are expected to cross them. This includes the weight the vehicle and any dynamic loads that may be introduced from movement of the vehicle. Dynamic loads may be from "bouncing" or from hitting a joint or pothole.
Initially it would seem obvious that ... | #### Which is more significant depends upon the bridge in question, certainly its length and the characteristics of the loading applied. For this discussion I am assuming highway traffic loading.
The question refers to dynamic effects, and it is worth noting that this is more than just impact from striking a pothole.... |
I'm giving SolidWorks a try and am following one of their tutorials on creating a part. When I create circles they are looking a bit "boxy" to me. My graphics card has 512MB of ram and I have checked the rendering settings that I found and everything seems to be OK - but I would have expected something more "circular" ... | #### Yes, this is normal. By default, SolidWorks renders curves on the screen using less than the highest possible level of detail that your monitor is capable of displaying. The point of this is to allow the screen to be redrawn quickly as you edit your design and change the view. The more detailed the curve, the long... |
What with all the work done by the FAA recently on regulating drone usage, I thought it would be nice to turn my eyes to the sky for another, less-known type of aerial denizen: the <a href="https://en.wikipedia.org/wiki/Airborne_wind_turbine" rel="noreferrer">aerial wind turbine</a>.
Wikipedia has all the relevant inf... | #### I think you may be misinterpreting aerial wind turbines as a type of aircraft. The FAA section of the Code of Federal Regulations defines an aircraft as <a href="http://www.ecfr.gov/cgi-bin/text-idx?SID=f5ac1e30d58cfc9185ccd1cb128c617b&node=pt14.1.1&rgn=div5#se14.1.1_11" rel="nofollow">a device that is use... |
In the US, typical structural steel welding is covered by either AWS D1.1 or AWS D1.5 (bridges). Both of these codes cover a wide range of carbon steels.
AWS has a separate code for welding stainless steels, AWS D1.6. There is some mention of welding to carbon steels, but this is mostly talking about choosing the fill... | #### According to <a href="http://awo.aws.org/wp-content/uploads/2014/stainlessconference/Campbell-AnUpdateonAWSD16StructuralWeldingCode-Stainless%20Steel.pdf" rel="nofollow">this slideshow</a> it looks like a weld between stainless and carbon or low-alloy steels would be within the scope of D1.6 entirely. It would not... |
I've seen it in several data sheets - it is a measure of error of some kind, of course. The problem is I dont know the exact meaning. I've seen it in the context of repeatability, accuracy and linearity.
An example is the following data sheet: <a href="http://www.smcpneumatics.com/pdf/americansmc/ZSE40_ISE40/ZSE40_and... | #### FS = FULL SCALE = maximum reading.
It means that the accuracy is such that the reading is <strong>probably</strong> within + or - 0.5% of the <strong>FULL SCALE</strong> reading.
This is a very important and easily overlooked qualification of the result.<br>
If I have a reading of 1 Volt and the accuracy is +/- ... |
Most introductory books on control theory usually start their <a href="http://en.wikipedia.org/wiki/State_observer">state observation</a> part by introducing the Luenberger observer, and after that they might continue by introducing the <a href="http://en.wikipedia.org/wiki/Kalman_filter">Kalman filter</a>. When readin... | #### I can only speak for the industry I have worked in (heavy machinery). I have only seen Kalman filters used in practice as observers.
Most of the data sources in heavy machinery tend to be quite noisy (pressure or accelerometer sensors). Kalman filters (as compared to simpler Luenberger observers) provide better ... |
The <a href="http://en.wikipedia.org/wiki/Tsar_Bomba" rel="nofollow">Tsar Bomba</a> packed a yield of 50 megatons into a package 2.1m in diameter by 8m long. Assuming that the lead tamper modification was not used (which boosts the yield of the Tsar Bomba design to 100 megatons), how much would the yield scale as a mu... | #### I am also not a nuclear engineer, but here are my thoughts on it:
My impression is that you might have trouble scaling a weapon in an arbitrary dimension but that they should scale basically linearly with mass assuming an acceptable configuration of the weapon.
In practice you reach a maximum size for your h-bom... |
The situation is a steel baseplate that has to be anchored to concrete to resist lateral loads.
<img src="https://i.stack.imgur.com/7yWzS.png" alt="base plate with 8 holes">
The lateral load on the base plate is great enough that more than one or two anchor rods are required. The base plate has room for 8 anchor ro... | #### <a href="https://www.aisc.org/uploadedFiles/Research/Research_Reports/Kanvinde%20-%20Shear%20Transfer%20in%20Exposed%20Column%20Base%20Plates.pdf" rel="nofollow">This report (large PDF warning)</a> on base plate design says that the AISC <em>Steel Design Guide I</em> instructs the use of plate washers fillet welde... |
Imagine I have an important axle in the gearbox of a motor. I want to support it with ordinary <a href="https://en.wikipedia.org/wiki/Ball_bearing" rel="nofollow">ball bearings</a> at several places along its length. I need both the outer and inner races to stay at fixed diameters at a fixed distance from each other.
... | #### The number of balls in a bearing affects a couple of different properties of the bearing:
<ul>
<li>Bearing Speed</li>
<li>Bearing Strength</li>
<li>Bearing Life</li>
<li>Bearing Cost</li>
</ul>
A <strong>Full Complement</strong> bearing means that the bearing has as many ball as can physically fit. Having the ma... |
It may just be my perception, but it seems like water main breaks (at least in Pittsburgh PA) are more common in the winter during the cold weather. It may just that they are more news worthy in the winter (water+cold=ice > news).
Are water mains more likely to break in the winter? If so what can be done to limit or... | #### Water main failures are greater in the winter months than in the spring or summer. As a water utility professional in northern Illinois we have around 120 failures each year with 20 + years of data. Each and every year we have 90 of the 120 between December and March (Fact). The question that indeed is hard to def... |
I have a small <a href="http://en.wikipedia.org/wiki/IP_Code" rel="nofollow">IP66</a> <a href="http://www.hammondmfg.com/1554FLP.htm" rel="nofollow">polycarbonate enclosure</a> with a <a href="http://en.wikipedia.org/wiki/Oxygen_sensor#Zirconia_sensor" rel="nofollow">Zirconia-based oxygen sensor</a> which produces sign... | #### You could pre-cool the gas entering the enclosure, the heat would then go into re-warming up this gas.
This could be done by passing the gas through a simple finned radiator-pipe in a temperature controlled environment (basically a pipe through a fridge/freezer). This might be a good way to do it if you want to c... |
I'm doing an investigation about building a bridge over a railway line and its <a href="http://en.wikipedia.org/wiki/Overhead_line#Overhead_catenary" rel="nofollow">catenary system</a>. I'm mainly interested in the electromagnetic environment on the bridge as it is affected by the presence of the catenary.
Is this an ... | #### "standard EM interaction range" depends a <strong>lot</strong> on frequency, or its inverse which is wavelength. Your 25 kV catenary probably is 50 Hz or 60 Hz, same as your national grid. That means the wavelength is 6000 kilometers. That's far more than your dimensions.
Hence, you can ignore the electro-magneti... |
I am constructing an autonomous, unmanned boat for voyages of several months. Traditional autopilots use a linear actuator to move the tiller but require several adjustments per minute. They will consume a lot of electricity and probably wear out mid-voyage. We are looking at wind-vane designs to steer the boat. Win... | #### I believe the simplest modification to the drawing that meets the requirements is to replace the top disk in the coupler with a standard spur gear. Replace the bottom disk with a worm gear engaged with the upper gear. This would allow the top to be rotated to the desired position, while the bottom only would rotat... |
According to BS5950, a beam section can be classified as plastic, semi-compact, compact or slender. For the same section area, a H-beam can take axial compression (without buckling) better than an I-beam, and as such, uses a different strut curve in the code:
<img src="https://i.stack.imgur.com/JQFqH.png" alt="enter i... | #### BS5950-1:2000 Clause 1.3.23 defines an H-section as having "<em>an overall depth not greater than 1.2 times its overall width</em>", and Clause 1.3.25 defines an I section as having "<em>an overall depth greater than 1.2 times its overall width</em>".
Note that at exactly a ratio of 1.2, it would be an H section ... |
I'm building a software application that uses GPS for a purpose related to roads.
I'd like to know how many decimal places of GPS data should be stored to provide measurements that are accurate to within a few feet?
| #### The circumference of the earth is about 25,000 miles <em>[40,075 km]</em>, or 131.5 Mfeet. That divided by 360 is 365 kfeet/degree <em>[111.3 km/degree]</em>. A degree value with 4 decimal places has a implied accuracy of 0.00005 deg, or 18 feet <em>[5.5 m]</em>. That's roughly the accuracy of a typical consume... |
Lightning strikes have been known to cause massive amounts of <a href="http://www.lightningmaster.com/White-Papers/Lightning-Damage" rel="noreferrer">damage</a>. The <a href="http://www.lightningsafety.com/nlsi_lhm/lpts.html" rel="noreferrer">stats on a lightning bolt</a> are:
<blockquote>
current levels sometimes i... | #### The current limit specification for a wire is limited by the heat that current will produce, and how much heat the wire can dissipate before getting too hot. "Too hot" depends on the circumstances. You will see higher current ratings for the same type of wire in chassis wiring applications than the electrical co... |
Measuring things like a martial artist's strike can be challenging because it is a complex motion and common vernacular will use imprecise or incorrect terms. This question is an attempt to identify the applicable measurements (quantification) and the correct units behind those numbers.
<hr>
<em>Background:</em><br>... | #### A martial artist's live strikes can be quantified between practitioners using <strong>force applied as pounds per square inch</strong>. The basic premise is (of course) force equals mass times acceleration. The importance is pairing with the <strong>area of contact</strong> used with which it is delivered - <str... |
I am reading a novel set in the future. A planet has been found where there are extensive deposits of diamond. Presumably diamond is mined much like marble is here on earth (there is not a lot of detail on this).
A character has a knife where the blade/shaft is a single piece of diamond. In 2015 here on Earth you can ... | #### These people just arent getting it. A diamondoid knife made from nano structured diamond would have the hardness of diamond but the elastic toughness and plastic deformation of steel. You would use molecular assemblers to make this. These are manmade enzyme like machines that bond carbon atoms into diamond composi... |
I used LabView for a lot of my BME undergrad, but the labs focused mainly on things dealing electrical signals.
In the real world I'm working mostly on ME projects, but we lack a good deal of experimentation equipment.
What are the limitations of LabVIEW as it relates to ME experiments?
| #### LABVIEW can be easily be used for ME related experimentation.
One such example would be to use an actuating mechanism to exercise a user interface on a mechanical DUT, which dispense a specific material quantity into a holding container. The weight of the material is measured using a weighing scale which communic... |
I have a metric thread pitch gauge that came in a tap and die set, it has pitches like $0.75$, $0.8$, $1.25$, etc. which is the distance between each thread. However there are two gauges that say $27$ and $28$ - I thought maybe it means $0.28\text{ mm}$ or possibly $0.28\text{ inches}$ if they threw in some non-metric ... | #### As mentioned these are 'teeth per inch' threads. they find their way onto metric thread gauges because BSP threads are still the standard in many countries for tings like gas fittings.
This is partly because of legacy issues where it would simply be too much hassle to change over millions of fittings on things l... |
I was thinking about fighter aircraft like the <a href="http://en.wikipedia.org/wiki/Hawker_Siddeley_Harrier">Harrier</a> which have <a href="http://en.wikipedia.org/wiki/Thrust_vectoring">thrust vectoring</a> and computer-controlled stabilisation nozzles. Also an <a href="http://en.wikipedia.org/wiki/Dihedral_%28aeron... | #### Helicopters are proof you don't need wings at all.
However, short wings (left right), no matter how long (front back), are less efficient than wide wings. You can see this from basic physics without having to understand anything about how wings actually work.
Consider a plane in straight, level, and steady flig... |
In submerged conditions galvanic corrosion effects exist between metals with dissimilar nobleness and the presence of seawater as electrolyte.
Does reducing the contact area by using an nonconducting paint <em>on the interface layer between the two metal parts</em> help delay this process? Or is any the solid contact ... | #### No solid contact is required at all, as the seawater provides the electrical route. In order to prevent galvanic corrosion, you would need to electrically isolate your two metals. That said, I can see that a solid electrical route would allow faster transfer of electrons, speeding up corrosion, and hence having no... |
<strong>The setup</strong>
Consider a cylinder inside another cylinder (placed with their symmetry axis horizontal).
The inner cylinder is about Ø100 mm in diameter and a centimeter or two in lenght/thickness. On the perimeter there is a thread. This cylinder is <strong>fixed</strong> in rotational motion, and cannot... | #### The simplest solution would be to use a spring such that it exerts a small force to push the moving cylinder back in. As it 'unscrews' the spring will be tensioned (or compressed) and as the wheel starts spinning the other way, the small force will help the thread to re-enter.
|
As I was browsing <a href="http://www.greenbookee.com/iso-965-1/" rel="nofollow noreferrer">ISO 965-1</a> it defines tolerances on a plenty of variables regarding metric threads, but it gives the pitch of the thread as a simple number from an allowed set ( 3 – 2 – 1,5 – 1– 0,75 – 0,5 – 0,35 – 0,25 – 0,2 ), and no toler... | #### I think the pitch is implied by the major and pitch diameter.
The tolerance of these $D_{maj}$ and $D_{pitch}$ are given in <a href="http://en.wikipedia.org/wiki/ISO_965" rel="nofollow noreferrer"><code>ISO 965-2</code></a>
I'll attempt juggling with the math in the <a href="http://en.wikipedia.org/wiki/ISO_met... |
In a program on <a href="http://www.npr.org/2015/02/25/389008046/a-hard-look-at-the-risks-of-transporting-oil-on-rail-tanker-cars" rel="noreferrer">NPR</a> that I was listening to, there was a bit about a bridge that from the description sounded to a layman as unsound and is still in use. The program described it as an... | #### In the United States, you can often use <a href="http://nationalbridges.com/" rel="nofollow">nationalbridges.com</a> and <a href="http://uglybridges.com/" rel="nofollow">uglybridges.com</a> to ascertain the current status of a bridge, along with some basic information about the owning agency/maintenance agency. Or... |
I am now in charge of a product line my company has been shipping for a decade. One of the previous product engineers was... shall we say, less than conscientious about sustainability and proper documentation. We have shipped hundreds of units, of multiple design variants, under the <em>exact same part number</em>. The... | #### Tracking the various product versions by serial number is a good idea, but be careful to standardize that as well. Years ago while working for an electronics manufacturer in service and repair, I discovered two units; one was serial number 0024, the other was 00024. They had changed from a four-digit number to a f... |
The <a href="https://en.wikipedia.org/wiki/Concorde" rel="nofollow">Concorde</a> had a famously high <a href="http://www.boeing.com/commercial/aeromagazine/aero_12/whatisaoa.pdf" rel="nofollow">angle of attack</a> (and <a href="https://www.aviation-history.com/theory/angle_of_attack.htm" rel="nofollow">pitch angle</a>)... | #### A long trapezoidal wing grows significantly in lift coefficient and area through flaps/slats and Fowler flaps, respectively. Delta wings, especially those using elevons, essentially have no capability to employ high-lift devices. A confluent design driver for delta wings is that they stall only at very high angl... |
I am trying to use a Piezo Electric Ceramic Disc Transducer for ultrasonic sensing measurements for fluid levels. A Piezo Ceramic Disc with a Resonant frequency of 215 KHz or 1 MHz is under consideration. These devices specify a Radial and Thickness mode vibration configuration.
<img src="https://i.stack.imgur.com/3f84... | #### Texas Instruments has extensive material on this Piezo Electric disc for applications of measurements fluid level. You can search their website for <a href="https://www.steminc.com/PZT/en/piezo-disc" rel="nofollow noreferrer">STEMINC</a> and you will see two discs used on Thickness mode. Both discs have frequency ... |
I am involved in an upcoming product launch and we recently had a discussion about serial numbers. We will of course use variant-specific model identifiers and revision numbers, but couldn't see any good reason to include any leading zeros in serial numbers, or otherwise make them fixed-length with padding numbers, pre... | #### Fixed-width serial numbers are just easier to handle. It also allows you to know where the serial number is within a overall product ID string without special rules to parse the string.
For example, if the serial number is expressed in hexadecimal in the string, it can contain letters A-F in addition to the digi... |
I am specifying a product made in Australia, which is made of "Grade 520 Steel." The manufacturer of the product lists a minimum yield stress of 520 N/mm² (75,400 psi) and a minimum ultimate stress of 650 N/mm² (94,300 psi) with a minimum elongation of 20% and Young's modulus of 205 kN/mm² (29,700 ksi.) They describe t... | #### I saw some material for tension rods that match the material properties that you gave, but these places do not list the steel used. It might be proprietary:
<ul>
<li><a href="http://www.ronstanrigging.com/arch_w/systemrange.asp?RnID=704" rel="nofollow">Ronstan</a></li>
<li><a href="http://www.daversteels.co.uk/ba... |
<strong>Downdrag</strong><br>
<a href="https://www.dot.state.oh.us/Divisions/Engineering/Geotechnical/Geotechnical_Documents/2007%20Workshop%20Downdrag%20in%20Foundation%20Design.pdf" rel="nofollow">Downdrag</a> in foundations occurs when soil layers consolidate and settle under additional load. This typically occurs w... | #### It depends on the construction sequence and support conditions; however in my experience most walls like these are built by installing the piles and then excavating the open side.
As you've noted, consolidation settlement is a concern for piles because the 'downdrag' force effectively reduces their capacity as a ... |
What happens to the working of petrol engine when it is emptied and filled with diesel or to a diesel engine emptied and filled with petrol? Will the engine be able to operate and, if not, why not?
| #### IC engines work in cycles, in a four-stroke IC engine there are four cycles
<ol>
<li>Intake stroke</li>
<li>Compression stroke</li>
<li>Combustion stroke</li>
<li>Exhaust stroke</li>
</ol>
During intake stroke the air-fuel mixture is sent into the engine cylinder, later in the compression stroke, it is compresse... |
I'm thinking of developing a pocket 'power bank' that could provide both 6V and 12V - a charger to charge either a phone (with 6V) or a notebook computer (with 12V).
The electrical diagram is simple enough; switch attachment of the terminals like below.
<img src="https://i.stack.imgur.com/CVHVv.png" alt="schematic... | #### I made a fast drawing with a bit more proper electronic:
<a href="https://i.stack.imgur.com/iOoRr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iOoRr.png" alt="voltage switcher"></a>
You cannot put two electrical sources in parallel, this will break your system imediatelly or on the long term... |
As a follow up to <a href="https://engineering.stackexchange.com/questions/1864/how-should-the-public-raise-questions-about-unsafe-structures-in-the-united-stat">this question</a>, I wonder if structural integrity monitoring information can be provided real-time and to a sufficient degree that safety decisions can real... | #### Real-time monitoring can be done and has already been done. The technology is there and as pointed out by hazzey, is a matter of cost versus the risk involved.
As a practising Engineer, I am/was involved in two deep excavation projects in two different countries where a cut-and-cover tunnel is/was constructed rig... |
On a recently launched Russian diesel-electric submarine, the rear propeller has two distinct features. You can see spheres at the base of every propeller blade:
<img src="https://i.stack.imgur.com/vDXwO.jpg" alt="">
Also, the trailing edge of the shaft has four adjoining fins in line with the axis of rotation:
<img... | #### Submarine propulsor designers are least concerned about hub vortex cavitation as they are primarily concerned about cavitation inception, or the onset of cavitation, which first occurs in the tip vortex regions, where the velocities are highest. Once cavitation occurs you are no longer operating in stealth mode. ... |
<a href="http://en.wikipedia.org/wiki/Turbo-compound_engine" rel="noreferrer">Turbo compound</a> engines extract some exhaust energy by using it to power a turbine connected to the driveshaft. Why are these engines not more widely used?
| #### I’ve been doing a lot of reading on this and what we haven’t seen is a form of turbo compounding but instead using a small turbine engine capable of running itself when a steady torque is required. If married to a reciprocating engine with variable valve timing, the valves could be held open; the turbine generatin... |
I have a rf module transmitting from an antenna. As you see in Figure 1, I have a radio mast that sends waves in all directions. I don't want this. My plan for controlling wave direction is Figure 2.
How do I control RF wave direction?
<img src="https://i.stack.imgur.com/z5sj6.png" alt="enter image description here... | #### Directional antennas generally use one of two priciples: Reflection or phasing.
Reflection works just like it does with optical mirrors, except that the wavelength is much much longer and therefore the construction of something that reflects may seem unintuitive. Most of the world's really high gain* antennas ar... |
I thought my electric car charging unit uses 6.6 kW of power. However, I found the label and it actually says 6.6 kVA. When I saw this I thought something along the lines of...
<blockquote>
Well, $ P=VI $, therefore kVA must be the same thing as kW... strange, I wonder why it's not labelled in kW.
</blockq... | #### Another way to understand why kVA is different to kW, is the Power triangle.
<a href="https://i.stack.imgur.com/H69PY.png" rel="noreferrer"><img src="https://i.stack.imgur.com/H69PY.png" alt="enter image description here" /></a>
<strong>Figure 1: power Triangle (source: <a href="https://www.electricaltechnology.or... |
...or in other words, why doesn't the material just stick to the screw, rotating in place, without progressing along its length?
In the simplest case, the answer is obvious: gravity. If it's a granular or liquid material and the screw is tilted to a side, it will just roll/slide/flow along the blade, to remain on the ... | #### This is effectively an addition to other answers:
<strong>An original Archimedes screw for liquids does not work as most people imagine it does,</strong><br>
and the diagram does NOT show how an original Archimedes screw works for fluids. The diagram is valid - it's just of something else which works in a similar... |
Does the dead weight tester technology provide capability for an accurate, low pressure calibration standard in the range of zero to 150 cm H<sub>2</sub>O, and if so is there a manufacturer that provides such an instrument?
If not, what is the best primary standard for that range of pressure in terms of accuracy?
I s... | #### In this situation, you might do just as well to use a U-tube manometer. Is some respects, this is a sort of dead-weight tester where the fluid itself is the dead weight. In this device pressure is determined from the difference in height between two connected volumes of fluid. Usually this is just a transparent t... |
I work in the middle of London, in an area full of large office blocks. Across the road from my office they have started construction of a large building (10 stories plus). Over the last few weeks, diggers have dug a large (and vertical walled) hole. Lorries have taken the resulting dirt and old concrete away, leaving ... | #### In addition to the other answers, some soils (e.g. clay) expand and contract as their moisture content changes, and wet soil expands as it freezes. This movement is rarely even across site, and differential movement causes a building to crack.
Foundations are dug down to below an expansive soil and below the fros... |
Whenever I've come across notation for specifying how much reinforcing steel is in a member, it is typically by giving the area of steel as a percent of the cross-sectional area of the member.
<img src="https://i.stack.imgur.com/eO22J.png" alt="enter image description here">
For example in this picture, you could say... | #### Your second bar description is what you need to compare it to:
<blockquote>
#8 @ 12" O.C.
</blockquote>
A #8 bar is 0.79 in<sup>2</sup>. This gives us $\frac{0.79in^2}{12in}$ or in<sup>2</sup> over in. This is the similar to your mm<sup>2</sup>/mm. (Obviously the units are not interchangeable!)
This method of... |
We are working on some equipment that is going to be attached to existing, 3,000 psi reinforced concrete floor slabs. In some locations, the best way to do this is to through-bolt and 'sandwich' the slab with a piece of threaded rod (5/8" rod in our case.) On the top side of the slab, our equipment has a large steel be... | #### There are some standard square washer sizes. These may not specifically be for your configuration, but they may help to decide on a size to start with.
<ul>
<li>ASTM F 436 Square Washers are found in the AISC Steel Manual on the table that shows other bolt and washer diameters. These are specifically for beveled ... |
I am interested in a microcontroller for a low power application. I have been advise to look at MSP430 or Microchip PIC microcontrollers. I also wonder if <a href="http://www.arm.com/products/processors/cortex-m/cortex-m0.php" rel="nofollow">ARM-Cortex-M0</a> is a good choice too.
At a high level the system will have... | #### When low power consumption is important, you have to look at the whole picture. A microcontroller with low Joules/cycle is only one thing to look at.
A good start would be to pick a battery and micro combination where the micro can run directly from the battery over the useful voltage range of the battery. Many... |
<a href="http://en.wikipedia.org/wiki/Sinkhole" rel="noreferrer">Sinkholes</a> have been known to occur in the <a href="http://www.cnn.com/2014/08/05/world/asia/seoul-skyscraper-sinkholes/" rel="noreferrer">middle of cities</a> or <a href="http://corvettemuseum.org/enews/backups/media/sinkhole.htm" rel="noreferrer">oth... | #### Whether it's natural subsidence, like sinkholes or human induced subsidence like the collapse of underground engineered chambers or mining subsidence the two ways of dealing with it are backfill or leaving it alone and the enforcement of an exclusion zone.
Where backfill is used for the remediation of subsidence ... |
Is the smaller gear (pinion) always mounted to the input shaft when meshed with a bigger gear that is mounted on the output shaft? Are there places where the bigger gear drives the smaller gear?
| #### Any mechanical clock or watch relies on the motive power applied to the large gear (the "wheel") which drives the smaller one (the "pinion"). Thus the weight in a longcase clock is suspended by a cord, rope or chain from the "great wheel" (usually making a rotation every 12 hours) and the rate of rotation is gear... |
Pressure treated lumber is specified for many exterior applications because of its resistance to insect damage and fungal rot. But how does it compare to untreated wood, mechanically?
For example, consider a rim joist supporting the ground floor of a residential structure with a pier and post foundation. If the joist ... | #### Pressure treatment does have a small, but documented effect on the strength of the member, particularly if it is 'incised' (has slots or holes cut into it as part of the pressure treating process.) If you're working to American codes, according to the <a href="http://www.awc.org/helpoutreach/faq/faqFiles/Pressure_... |
A <a href="https://en.wikipedia.org/wiki/Epicyclic_gearing" rel="noreferrer">planetary gear</a> is a gear that rotates not around an axle but around another gear known as a sun gear, or star gear. I have designed prototype systems in the past that used a single planetary gear rotating around a rotating gear. However si... | #### <strong>Advantages</strong>
I'll start off by quoting from the "Benefits" section of <a href="https://en.wikipedia.org/wiki/Epicyclic_gearing#Benefits" rel="nofollow">the Wikipedia article</a>:
<blockquote>
The load in a planetary gear train is shared among multiple planets, therefore torque capability is grea... |
Chainsaws use oil to lubricate the chain. The usage is quite minor, probably less than 1cc per minute of work. The oil is normally supplied from a refillable compartment to the chain only when the chainsaw is running.
How is the delivery managed?
A pump? The capillary effect?
If it's a pump, I'd be interested in de... | #### I sent this question along to a forester of 20+ years and this was his response:
<blockquote>
So...... back in the day......... the first saws had a manual oiler.
This was a younger lumberjack in training who operated the oil can. He
held this job until one of the more senior lumberjacks cut off
something... |
In common US usage, the heights of tall things are sometimes converted to a "number of <a href="https://en.wikipedia.org/wiki/Storey" rel="nofollow">stories</a>". The thinking is that people can better compare heights to similar tall buildings that they might have seen.
The US conversion is usually:
$$\text{Number of... | #### There's a handy-dandy table <a href="http://www.ctbuh.org/TallBuildings/HeightStatistics/HeightCalculator/tabid/1007/language/en-GB/Default.aspx" rel="nofollow">here</a>:
<pre><code> Office | Residential/hotel | Function Unknown
... |
I have got a spinning top from a Canadian manufacturer, and I am deeply amazed by how neatly it spins.
My interest in physics has led me to try to find out at what top speed I can spin the top and how that compares to other tops made from other materials and other shapes.
I have glued a little sticker to it and recor... | #### The answer could be to get hold of a high-speed LED stroboscopic light. How easy/expensive this will be depends on the angular speed you are dealing with. There are even some phone apps which will go to moderate speeds.
You tune the speed of the stroboscope to make the mark on your spinning top appear stationary.... |
When looking at thread descriptions, one of the <a href="https://en.wikipedia.org/wiki/Screw_thread#Lead.2C_pitch.2C_and_starts" rel="noreferrer">basic properties</a> is always the number of thread starts.
<img src="https://i.stack.imgur.com/HmBHi.png" alt="wikipedia thread starts">
As far as I could tell, all of the... | #### Advantages of double lead threading: Starting ease and eliminating cross-threading (i.e. happy customers).
Common usages:
<ul>
<li>Any bottle cap or jaw lid</li>
<li>Catsup bottles</li>
<li>Tooth paste tubes</li>
<li>Split bolts (Kearneys)</li>
<li>Flash light end caps</li>
<li>Any assembly not requiring high t... |
I've heard the term <em>spiral curve</em> used to describe a section of highway that is more aesthetically pleasing to the driver's eye. However, I believe I've driven on enough road to say that I can't definitively tell the difference between any given curve other than how "sharp" it is.
Could anyone explain how one ... | #### Q: ...how one can determine if a section of curve on a highway is classified as a "spiral" curve, and are there other advantages besides "making it look good"?
A: The purpose of a spiral or transition curve has nothing to do with aesthetics. They were originally introduced on railways for safety reasons in conju... |
I have an 80 g·cm motor with a rotational frequency of 15,000 rpm. I want to lift a weight of 2 kg at a speed of 0.5 m/s. How do I calculate the gear ratio required?
| #### <blockquote>
I have a 80gcm motor with a rpm of 15000.<br>
I want to lift a weight of 2 kg at a speed of 0.5 m/s.<br>
How do I go about calculating the gear ratio required for this?
</blockquote>
<strong>Firstly - is it possible?</strong>
In particular, is there enough input power available for the desired... |
I have an welded steel mesh, like in the following image.
<img src="https://i.stack.imgur.com/qT2lx.jpg" alt="steel mesh">.
<ul>
<li>Material: steel</li>
<li>Diameter of the wires: 4mm</li>
<li>Mesh: 15x15cm</li>
</ul>
I found the following information about the welds:
<ul>
<li><strong>the minimal relative strengt... | #### The weld points will definitely be the limiting factor (think about a cargo net, where both the strands and joints are flexible, but usually the strands are straight and the joints are at whatever angle they need to be at to let the strands be straight.)
Since the "shear" strength is listed in linear kN I'm going... |
I need to replace the fan on my graphics card. The original fan is exactly like <a href="http://www.dhgate.com/product/original-for-sapphire-apistek-graphics-card/190676310.html" rel="nofollow noreferrer">this one</a> but there is another fan that seems to be a <a href="http://www.dhgate.com/product/original-sauter-ga5... | #### Factors determining fan airflow (heat reduction):
<ol>
<li>Blade pitch.</li>
<li>Blade shape and size.</li>
<li>Motor power and RPM.</li>
</ol>
In your case 3 is the same, 1 and 2 in the "newer version are bigger", so it will cool better.
Main source of noise in fans is coming from the bearing and the electrom... |
On old bridge plans I have occasionally seen a note to "burr threads after installation". This was done to keep the nuts of bolted connection from loosening all the way and falling off of the bolt.
An example of this practice can be seen in this <a href="https://books.google.com/books?id=bxAkAAAAMAAJ&pg=PA1524&... | #### I asked a friend who is a highly competent EE by day - but who restores super sized steam engines by night and collects olde heavy metal engines etc and has much experience with old large corroded items. His comments:
<hr>
It really depends on the specific situation.
For mild steel bolts in good condition whic... |
I was doing a question involving a T-Beam question wrong since I was selecting the wrong area to use for $Q_{max}$ when trying to maximise the shear stress.
$$\large{\tau}= \frac{VQ}{It}$$
A friend argued that the area both above and below the Neutral Axis should be equal but despite trying multiple times, I have bee... | #### The answer to the headline question is yes, it is equal. It physically has to be equal, since you can't have two different values of a particular directional stress at one point.
The quoted equation is for shear stress, where
V = total shear force at the location in question;
Q = first moment of area 'beyond' th... |
I am building a device that needs to be inside of a microwave oven but somehow needs to communicate with another device outside of the microwave.
How can I reflect microwaves so they don't come into contact with the electronics in the device, while still allowing the device to transmit and receive data?
The frequency... | #### <strong>Your best option for wireless communication in this situation is some kind of optical link.</strong>
<a href="http://en.wikipedia.org/wiki/Microwave_oven#Principles" rel="nofollow noreferrer">Consumer microwaves</a> typically operate at a frequency of 2.45 GHz and <a href="http://en.wikipedia.org/wiki/Blu... |
Suppose I want to ship my product via UPS, or whatever other professional carrier service. What vibration and shock forces should I design my product to withstand? And how can I effectively test my product against those forces?
| #### UPS has, or at least had when I was transit testing packaged products, a specific packaging test standard based on <a href="http://www.ista.org/" rel="nofollow">ISTA</a> standards and <a href="http://www.astm.org/Standards/D4169.htm" rel="nofollow">ASTM D4169</a>. There's also a MIL-STD, 810 something, but I don't... |
A common method of repairing old <a href="http://en.wikipedia.org/wiki/Rivet#High-strength_structural_steel_rivets" rel="noreferrer">riveted structures</a> is to <a href="http://www.state.nj.us/turnpike/documents/DCA2011SS-13-PAGES.pdf" rel="noreferrer">replace any damaged rivets with new high strength bolts</a>.
Whe... | #### According to AISC J1.9 rivets can be considered as sharing the load with high strength bolts, specifically in joints designed as slip-critical as per J3. The apply this section to both new work and alterations.
The commentary on this section points out that this is because the ductility of the rivets.
This means... |
I was reading up on <a href="https://en.wikipedia.org/wiki/Fly-by-wire" rel="noreferrer">fly-by-wire</a> development, and I saw a short section about <a href="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070013704.pdf" rel="noreferrer">fly-by-wireless</a> technology. It seems like a great idea, with the poten... | #### No, crossed communications would be a total non-issue.
Think of it like a home wireless network. All your devices at home can talk to each other on your WiFi network, and the same is true for your neighbour. But your devices can't talk to your neighbour's devices because they are on a different wireless network.
... |
I am a programmer facing an electronic question, so I thought here is the place to ask!
<ul>
<li>I have a magnetic field sensor which provides me with magnetic field values (XYZ axis) 250 times a second. </li>
<li>An electronic circuit with a programmable microprocessor controls a coil, which can change the magnetic f... | #### With a sample rate of 250 Hz, you could easily send 100 bits/second or more. In 0.5 second, that would be on the order of 50-60 bits.
The question is, what bit patterns should you select that are readily distinguishable from each other and also from outside noise and interference? A common solution is to use pseu... |
Trucks and smaller vehicles with diesel engines run on diesel fuel which looks more or less like kerosene - less flammable than gasoline, low viscosity liquid. However larger diesel engines <a href="https://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C" rel="nofollow">like this 120 thousand horsepower marine ... | #### Diesel and heater oil are the same thing , the tiny difference is the additive package ( a fraction of 1 % of the total). Diesel may have a better additive to prevent wax from crystallizing and plugging lines in cold weather , for example. From time to time in various locations there may be different limits on sul... |
Suppose I have two parts with holes aligned and I have to install a solid rivet into the "combined" hole.
Clearly the rivet diameter must be slightly smaller than the hole diameter, otherwise it simply won't fit. So I heat this slightly smaller rivet, insert it into the hole and then deform its tail so that the rivet ... | #### The short answer is: <strong>Yes, as the rivet head is formed, the shank of the rivet is also deformed to fill the hole.</strong>
Just like structural bolts, rivets are installed in holes that are 1/16 inch larger in diameter than the rivet. This clearance allows for manufacturing imperfections and clearance for e... |
AFAIK when you heat up a piece of steel to high temperature and let it cool down slowly (as opposed to shock cooling by say submerging it into water) steel gets softer - that's called tempering. Steel getting softer means it can bear less load without getting deformed.
Suppose we connect parts of steel skyscraper with... | #### Structural steel are not usually intended to be heat-treated.
Heat treatment involves heating the steel beyond a critical temperature (typically around 850 °C) and then cooling it rapidly to change its crystal structure. This results in a 'stressed' structure which tends to increase tensile strength and hardness... |
I was once told that the speed limits on banked highway curves (specifically off-ramps) were determined by assuming zero friction between the car and the road, such that as long as you stayed on the correct path of travel, the banking of the curve would prevent a vehicle from sliding outwards. That is, the angle of the... | #### This information comes from a <a href="http://www.iowadot.gov/design/dmanual/02a-02.pdf">design document</a> by the Iowa DOT (US). It might not apply everywhere in the world, but the considerations are probably universal.
For clarity, the amount of banking of a turn is typically called <em>super elevation</em>. A... |
Some roadway intersections that are near railroad tracks have signs that light up when a train is approaching. These signs warn that certain turns are not allowed because of the train. One of these signs is shown below from the <a href="http://www.edmonton.ca/transportation/ets/safety_security/lrt-traffic-signs-and-sig... | #### The answer is slightly more complex than what the OP proposes -- this is due to two factors:
<ol>
<li>The interconnect must be <em>fail safe</em> -- i.e. if the interconnect circuit fails, the system must be able to detect this and report a problem to both highway and railroad maintenance crews. To this end, spe... |
I'm an artist building a project which one could think of as a "sliding door" – a very narrow panel running on grooved wheels riding in tracks at top and bottom. It will be motorized and driven by a stepper motor, timing belt and pulleys. I will probably end up driving it from top and bottom too so it doesn't rack.
T... | #### Driving from the top is better. If you think about it on an intuitive level, when you pull from the top, the weight of the unit 'wants' to stay under the wheels, so your door tends to stay straight up and down. If you pull from the bottom, the weight of the door is tempted to lag behind and tip over, causing the w... |
In designing mechanical parts in an assembly, sometimes the mating surfaces are raised faces. I've been told it's to provide a better seal. However, for piping (flanges), it seems to be the consensus that a raised face flange does not provide any extra seal functionality, but has more to do with the manufacturing metho... | #### In general you would raise mating surfaces in order to make them easier to machine.
Having the surface raised above the surrounding material means that you don't have to worry so much about tools colliding with edges of the feature and it's fairly intuitive that skimming a raised surface is a simpler operation th... |
I found the following comments on direct and indirect control in <a href="http://www.elsevierscitech.com/pdfs/JPC_SurveyPrize.pdf">"Survey on iterative learning control, repetitive control and run-to-run control." by Wang, Gao, and Doyle</a>:
<blockquote>
There are two application modes to use the learning-type cont... | #### I have only skimmed through the paper. The terminology is put forward by the paper to organize it.
Figure 6 in the paper is the key (bottom of page 1595). That is a diagram of indirect learning control.
Here, the learning controller takes two inputs: one is the system output, and the other is the output of the '... |
In case of Uranium, things are lot easier, because $UF_6$ is gaseous from around 60 $\,^{\circ}\mathrm{C}$.
I know, that in most cases, plutonium isotope separation is not needed, because there is no need to separate its fissile isotopes. But there is an exception: <a href="https://en.wikipedia.org/wiki/Radioisotope_t... | #### Pu238 is not usually isotopically separated from spent nuclear fuel for exactly the reason you pointed out, it would be very difficult. Instead most of what we have comes from one of two different processes.
The first is bombardment of Np237 (also made in a nuclear reactor) with neutrons. It will become Np238 and... |
I have a vibration motor contained in an object. The motor looks similar to this:
<img src="https://i.stack.imgur.com/ww4Eq.jpg" alt="Typical vibration motor">
When the motor is running, I want to simulate the movement of the container object that results from the vibration of the motor. I'm able to model the parts/a... | #### @Narada is correct, but I their answer is a bit short on detail, so I will expand on it.
<h1>Calculating Force</h1>
First, you can calculate the force that the motor exerts on the containing object from the acceleration of the mass at the end of the motor shaft. As the mass rotates, it accelerates toward the mo... |
<strong>Construction Joints</strong>
Construction joints in concrete footings or walls are places where the concrete pour can be stopped so that everything doesn't have to be poured at once. Later, once the concrete has hardened, the next part of the concrete can be placed against the previous pour. These locations ar... | #### Typically one does not consider the key when checking a slab - footing interface. This is based on ACI318 Section 15.8.1.4, which discusses the transfer of lateral forces to footings and directs the reader to Section 11.6. 11.6 which says this,
<blockquote>
11.6.3 A crack shall be assumed to occur along the she... |
We have a simple class 1 lever:
$$\begin {array}{c}
\text {5,000 kg} \\
\downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarro... | #### A uniformly distributed load can be considered to act in its centre. Working in kg and m:
Clockwise moment about the left hand end = 5000 * 2.5 = 12500
Anticlockwise moment about the left hand end = F * 1 (where F is the reaction at the fulcrum)
These must be equal for it to be balanced, giving F=12500kg
Resolv... |
I have seen several block diagrams with diagonal inputs, drawn with an arrow through the block.
<img src="https://i.stack.imgur.com/tHTpI.png" alt="enter image description here"> <a href="https://www.google.com/search?q=indirect+adaptive+control&biw=1550&bih=720&source=lnms&tbm=isch&sa=X&ei=CYY... | #### The diagonal input generally means that it changes some parameter of the block, such as its gain, without otherwise becoming part of the signal that the block is processing.
|
I think, it could lead to, for example, very environment friendly <em>and</em> very efficient urban traffic.
But I also think, it required very precise part construction.
Do such things exist? At least in plan?
<em>Extension:</em> Clarification added, waiting for acceptable answer again.
<em>Extension #2:</em> Desp... | #### If you count gasoline as "gas", many car manufacturers are already testing homogeneous charge compression ignition engines. It is where they use the compression stroke to ignite the fuel mixture in the cylinder. The fuel is not direct injected, it is premixed in the intake charge before it makes it into the cylind... |
I am new to mechanical engineering, although I have a scientific background (postgrad in Mathematics), and I (mostly) code for a living.
I have an idea about creating a mechanical device; I envisage it will entail gears, linkages and actuators.
I have a rough idea where things will fit but I would like to be able to te... | #### <blockquote>
I am new to mechanical engineering, although I have a scientific
background (postgrad in Mathematics), and I (mostly) code for a
living.
</blockquote>
My observation is that there are plenty of analogues between how software is designed, tested for, coded (heh, in that order), and distributed -... |
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