text stringlengths 16 3.88k | source stringlengths 60 201 |
|---|---|
0%
Present Value (Million dollar)
NPV (Million dollar)
0
900
-900
1
-900.0
162.1
1
1
900
300
300
2
600
1.28
384
0
216
0.917431
198.2
2
1
900
600
600
2
1200
1.28
768
0
432
0.84168
363.6
3
1
900
900
900
2
1800
1.28
1152
0
0
648
0.772183
500.4
Don’t worry, we’ll go through this just now…
ESD.70J Engineering Economy Module... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
dollar)
Variable Cost (Million dollar)
Investment (Million dollar)
Salvage (Million dollar)
Net value (Million dollar)
Discount Factor @ 8.0%
Present Value (Million dollar)
NPV (Million dollar)
0
300
-300
1
-300.0
156.5
1
1
300
300
300
2
600
1.5
450
300
2
2
600
600
600
2
1200
1.5
900
300
-150
0.925926
-138.9
0
0.857339... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
Tables (1- and 2-way)
– What Excel was presumably invented
for…
• Charts
• Goal seek
ESD.70J Engineering Economy Module - Session 1
27
Data Tables
• Use Data Tables to see how different input values
affect the output
• Data Tables provide a shortcut for calculating,
viewing and comparing multiple versions in one
c... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
Cont)
•
Step 3: create new output values
Select the range of cells containing the
formulas and values (no labels!)
–
– Go to “Data” menu, select “Table”
–
–
Data menu ⇒ ‘What-If Analysis’ in Excel 2007
•
Reference “Column input cell” to the input
variable whose value Excel varies as it
iterates through the Data Tabl... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
1
36
Two-way Data Tables
• Step 1: Create one column and one row
varying input values for each of the inputs
– Plan A variable cost varies from $1,200 to
$1,450; for Plan B from $1,400 to $1,600
– Incremental step $100
Step 1
ESD.70J Engineering Economy Module - Session 1
37
Two-way Data Tables
• Step 2: Enter the ... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
a try!
Check with your neighbors…
Check the solution sheet…
Ask me questions…
ESD.70J Engineering Economy Module - Session 1
41
Excel charts
• With the sensitivity analysis, we’ve
generated a lot data for ‘what-if’
scenarios
• Would it be great to generate a visual
aid to summarize this information?
ESD.70J Engineer... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
Goal Seek
• Vary (find) input value until the output equals
a desired target value
• Click “Goal Seek” under “Tools” menu on
Mac, Data ⇒ ‘What-If Analysis’ on PC
– “Set Cell”: cell whose value is changed to target
value
– “To Value”: desired target value
– “By Changing Cell”: precedent cell value affecting
desired ... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
than there are zeros in
the format
ESD.70J Engineering Economy Module - Session 1
52
Questions?
Comments?
Suggestions?
ESD.70J Engineering Economy Module - Session 1
53
Summary
• Excel is a powerful tool for decision-making
• We’ve just scratched the surface
• Good habits will make your life easier
– Separate input ... | https://ocw.mit.edu/courses/esd-70j-engineering-economy-module-fall-2009/5fa0b84793362aca263cb900be59ba34_MITESD_70Jf09_lec01.pdf |
The heat and wave equations in 2D and 3D
18.303 Linear Partial Differential Equations
Matthew J. Hancock
Fall 2006
1 2D and 3D Heat Equation
Ref: Myint-U & Debnath
2.3 – 2.5
§
[Nov 2, 2006]
Consider an arbitrary 3D subregion V of R3 (V
defined at all points x = (x, y, z)
find an equation governing u. The heat ener... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
�owing across the boundaries,
we sum φ nˆ over the entire closed surface S, denoted by a double integral
dS.
Therefore, the conservation of energy principle becomes
S
·
|
·
·
|
� �
d
dt
V
� � �
cρu dV =
nˆ dS +
φ
·
−
S
� �
V
� � �
Q dV
(1)
1
1.1 Divergence Theorem (a.k.a. Gauss’s Theorem)
... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
�z2 .
Applying the Divergence theorem to (1) gives
d
dt
V
� � �
cρu dV =
−
V ∇ ·
� � �
φ dV +
Q dV
V
� � �
Since V is independent of time, the integrals can be combined as
cρ
V
� � �
�
∂u
∂t
+
φ
−
∇ ·
Q
dV = 0
�
Since V is an arbitrary subregion of R3 and the integrand is assumed continuous, the
in... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
2D and 3D Wave equation
The 1D wave equation can be generalized to a 2D or 3D wave equation, in scaled
coordinates,
This models vibrations on a 2D membrane, reflection and refraction of electromagnetic
(light) and acoustic (sound) waves in air, fluid, or other medium.
utt =
2
u
∇
(6)
3 Separation of variables i... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
)
The 3D Heat Equation implies
′T
T
2X
= ∇ =
X
λ = const
−
(10)
where λ = const since the l.h.s. depends solely on t and the middle X ′′/X depends
solely on x. The 3D wave equation becomes
On the boundaries,
′′ T
T
= ∇
2X
X
=
λ = const
−
X (x) = 0,
∂D
x
∈
The Sturm-Liouville Problem for X (x) is
∇
... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
t) = Xn (x) Tn (t).
��
��
t + βn sin
�
λn
t
4
(13)
(14)
(15)
(16)
5 Uniqueness of the 3D Heat Problem
Ref: Guenther & Lee
10.3
§
We now prove that the solution of the 3D Heat Problem
u (x, 0) = f (x) ,
x
D
∈
is unique. Let u1, u2 be two solutions. Define v = u1 −
D
2 v,
vt =
x
u2. Then v satisfies
ut... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
∂D
� �
But on ∂D, v = 0, so that the first integral on the r.h.s. vanishes. Thus
Also, at t = 0,
dV
dt
(t) =
2
−
dV
v
2
|
0
≤
D |∇
� � �
V (0) =
v 2 (x, 0) dV = 0
(17)
(18)
D
� � �
≤
≥
0 and dV /dt
Thus V (0) = 0, V (t)
0, i.e. V (t) is a non-negative, non-increasing
function that starts at zero. Thus V... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
3D Wave Equation lead to the Sturm-Liouville
problem
∇
2X + λX = 0,
X (x) = 0,
D,
∂D.
x
x
∈
∈
(19)
6.1 Green’s Formula and the Solvability Condition
Ref: Guenther & Lee
8.3, Myint-U & Debnath
10.10 (Exercise 1)
For the Type I BCs assumed here (u (x, t) = 0, for x
∂D), we now show that
all eigenvalues ar... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
Result (22) applied to G = v2 and F =
∇
(v2∇
v1)
·
nˆdS =
S
� �
V
� � �
2
v1 +
v2∇
v1 · ∇
v2
∇
dV
�
�
Subtracting (23) and (24) gives Green’s Formula (also known as Green’s second iden
tity):
(v1∇
v2 −
v2∇
v1) nˆdS =
·
S
� �
V
� � �
�
This is also known as a Solvability Condition, since the values of v1 an... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
v defined on a volume V with closed smooth
surface S.
�
�
We now apply result (26) to a solution X (x) of the Sturm-Liouville problem (19).
Letting v = X (x), S = ∂D and V = D, Eq. (26) becomes
X
X
∇
·
nˆdS =
2XdV +
X
∇
2
dV
X
|
D |∇
� � �
� � �
D
∂D
� �
Since X (x) = 0 for x
∂D,
∈
Also, from the PDE in (... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
integrating and imposing the BC X (x) = 0
X is nonzero
∂D gives X = 0 for all x
∇
dV > 0. Thus,
If
for x
at some points in D, and hence by continuity of
from (31), λ > 0.
D , i.e. the trivial solution. Thus
2
X,
D |∇
∇
X
∈
|
� � �
7
�
6.3 Orthogonality of eigen-solutions to ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
are orthogonal.
� � �
D
7 Heat and Wave problems on a 2D rectangle, ho
mogeneous BCs
Ref: Guenther & Lee
[Nov 7, 2006]
§
10.2, Myint-U & Debnath
9.4 – 9.6
§
7.1 Sturm-Liouville Problem on a 2D rectangle
We now consider the special case where the subregion D is a rectangle
D =
(x, y) : 0
{
≤
x
≤
x0,
0
y
... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
r.h.s. only depends on x, both sides must
equal a constant, say µ,
Y ′′
Y
X ′′
− X
+ λ =
= µ
(36)
The BCs (34) and (35) imply
X (0) Y (y) = X (x0) Y (y) = 0,
X (x) Y (0) = X (x) Y (y0) = 0,
y
x
0
0
≤
≤
≤
≤
y0,
x0.
To have a non-trivial solution, Y (y) must be nonzero for some y
must be nonzero for so... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
Y + νY = 0,
≤
Y (0) = Y (y0) = 0
0
y0,
y
≤
(40)
µ. The solutions are the same as those for (38), with ν replacing µ:
where ν = λ
−
Yn (y) = bn sin
,
νn =
nπy
y0
�
�
nπ
y0
�
�
2
,
n = 1, 2, 3, ...
(41)
The eigen-solution of the 2D Sturm-Liouville problem (33) – (35) is
vmn (x, y) = Xm (x) Yn (y) = cmn s... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
to the T (t) problem
(13) and the Sturm-Liouville problem (33) – (35), respectively, to obtain
(x, y) : 0
{
x0, 0
y0}
≤
≤
≤
≤
x
y
umn (x, y, t) = Amn sin
= Amn sin
mπx
x0
mπx
x0
�
�
�
�
sin
sin
nπy
y0
nπy
y0
�
�
�
�
e −λmnt
−π2
e
„
2
2
m + n
2
2
y «
x
0
0
t
To satisfy the initial condition, we su... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
– (35). Multiplying both sides by v ˆ
�
( ˆm, ˆn = 1, 2, 3, ...) and integrating over the rectangle D gives
are the eigenfunctions of the 2D Sturm
(x, y)
mπx
x0
sin
mnˆ
�
�
�
f (x, y) v ˆ
mnˆ
(x, y) dA =
Amn
vmn
(x, y) v ˆ
mnˆ
(x, y) dA
(44)
∞∞
D
� �
m=1 n=1
�
�
D
� �
where dA = dxdy. Note that
x0
vmn
(x,... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
x, y) v ˆ
y0
mnˆ
D
x0
� �
f (x, y) sin
0
�
0
�
(x, y) dA
mπx
x0
sin
�
�
nπy
y0
�
�
dydx
(45)
7.3 Solution to wave equation on 2D rectangle, homogeneous
BCs
The solution to the wave equation on the 2D rectangle follows similarly. The general
3D wave problem (8) becomes
(x, y)
D,
∈
t > 0,
utt =
∂2u
... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
πt
� �
×
�
m2
2 +
x0
n2
2 + βnm sin πt
y0
�
� �
m2
2 +
x0
n2
2
y0
��
To satisfy the initial condition, we sum over all m, n to obtain the solution, in
general form,
∞ ∞
u (x, y, t) =
umn (x, y, t)
(46)
Setting t = 0 and imposing the initial conditions
m=1 n=1
�
�
u (x, y, 0) = f (x, y) ,
ut (x, y, 0) =... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
, (33) – (35). As above, multiplying both sides by
v ˆ
mnˆ
�
(x, y) ( ˆm, ˆn = 1, 2, 3, ...) and integrating over the rectangle D gives
�
�
�
αmn =
βmn =
4
x0y0
� �
4
x0y0√λmn
D
f (x, y) vmn (x, y) dxdy
g (x, y) vmn (x, y) dxdy
D
� �
8 Heat and Wave equations on a 2D circle, homo
geneous BCs
Ref: Guenther... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
, t) = u (x, y, t)
for
0
r
≤
≤
1,
π
−
≤
θ < π.
12
You can verify that
The PDE becomes
2
v =
∇
∂2v
∂x2 +
∂2v
∂y2 =
1 ∂
r ∂r
r
∂w
∂r
�
�
+
1 ∂2w
r ∂θ2
2
1 ∂
r ∂r
r
∂w
∂r
�
�
+
1 ∂2w
r2 ∂θ2 + λw = 0,
0
r
≤
≤
1,
π
−
≤
θ < π
The BC (48) requires
≤
We use separation of vari... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
)
which, in order to obtain non-trivial solutions (H (θ) = 0 for some θ), implies
w (1, θ) = R (1) H (θ) = 0
R (1) = 0
(53)
In the original (x, y) coordinates, it is assumed that v (x, y) is smooth (i.e. contin
uously differentiable) over the circle. When we change to polar coordinates, we need
to introduce an ex... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
m2 ,
Hm (θ) = am cos (mθ) + bm sin (mθ)
Thus, in general, we may assume λ = m2, for m = 0, 1, 2, 3, ...
The equation for R (r) in (52) becomes
r
d
dr
r
�
Rearranging gives
1
dR
dr R (r)
�
+ λr2 = µ = m 2 ,
m = 0, 1, 2, 3, ...
2 r
d2Rm
dr2 + r
dRm
dr
+
λr2
−
2
m
Rm =
0;
Rm (1) = 0,
Rm (0)
|
|
<
∞... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
the function Ym (s) is unbounded at s = 0. The general solution to the ODE is
¯Rm (s) = cm1Jm (s) + cm2Ym (s) where cmn are constants of integration. Our bound
edness criterion
at s = 0 implies c2m = 0. Thus
R¯m (0)
<
�
�
�
�
∞
¯Rm (s) = cmJm (s) ,
�
�
�
�
Rm (r) = cmJm
√λr
.
[Nov 9, 2006]
The Bessel Function ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
�
Note that the sum of numbers
(
−
1)k s2k+m
k! (k + m)!22k+m
L2k+m
k! (k + m)!22k+m
≤
�
�
�
�
�
L2k+m
k! (k + m)!22k+m
k=0
�
converges by the Ratio Test, since the ratio of successive terms in the sum is
L2(k+1)+m
(k+1)!(k+1+m)!22(k+1)+m
L2k+m
k!(k+m)!22k+m
=
L2
L2
(k + 1) (k + 1 + m) 4 ≤ (k + 1) 4
2
... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
Each Bessel function Jm (s) has an infinite number of zeros (roots) for s > 0. Let
jm,n be the n’th zero of the function Jm (s). Note that
1
j0,1 = 2.4048
j1,1 = 3.852
2
j0,2 = 5.5001
j1,2 = 7.016
3
j0,3 = 8.6537
j1,3 = 10.173
J0 (s)
J1 (s)
The second BC requires
Rm (1) = Rm
¯
√λ
= Jm
√λ
= 0
�
This has an... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
, y, t) = 0,
∂2u
∂y2 ,
(x, y)
u (x, y, 0) = f (x, y) ,
(x, y)
D,
∈
t > 0,
∂D,
∈
(x, y)
D,
∈
where D is the circle D =
. We reverse the separation of vari
1
}
ables (9) and substitute solutions (14) and (42) to the T (t) problem (13) and the
Sturm Liouville problem (47) – (48), respectively, to obtain
(x, y) ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
, 0)
=
vmn (x, y)
∞
∞
m=1 n=1
�
�
We can use orthogonality relations to find αmn and βmn.
9 The Heat Problem on a square with inhomoge
neous BC
We now consider the case of the heat problem on the 2D unit square
D =
(x, y) : 0
{
≤
x, y
,
1
}
≤
(62)
16
where a hot spot exists on the left side,
ut =
u (x, y,... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
,
{
u0/ε
0
�
y
y0|
< ε/2
}
|
−
otherwise on ∂D
The PDE for uE is called Laplace’s equation. Laplace’s equation is an example of
an elliptic PDE. The wave equation is an example of a hyperbolic PDE. The heat
equation is a parabolic PDE. These are the three types of second order (i.e. involving
double derivatives) ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
= c1e nπx + c2e −nπx
An equivalent and more convenient way to write this is
X (x) = c3 sinh nπ (1
x) + c4 cosh nπ (1
x)
−
−
Imposing the BC at x = 1 gives
X (1) = c4 = 0
and hence
Thus the equilibrium solution to this point is
X (x) = c3 sinh nπ (1
x)
−
∞
uE (x, y) =
An sinh (nπ (1
n=1
�
x)) sin (nπy)
−
You ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
π)
y0+ε/2
y0−ε/2
�
sin (mπy) dy
y0+ε/2
y0−ε/2
�
2u0
cos (mπy)
=
=
=
ε sinh (mπ) − mπ
�
2u0
εmπ sinh (mπ)
4u0 sin (mπy0) sin
εmπ sinh (mπ)
�
mπε
2
�
18
(cos (mπ (y0 −
ε/2))
−
cos (mπ (y0 + ε/2)))
Thus
∞
sin (nπy0) sin
nπε
2
uE (x, y) =
4u0
επ
n sinh (nπ)
�
To solve the transient proble... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
x)
≈
enπ(1−x)
enπ = e
−nπx
Thus the terms decrease in magnitude (x > 0) and hence uE (x, y) can be approxi
mated the first term in the series,
uE (x, y)
4u0 sin (πy0) sin
sinh (π)
�
≈ επ
πε
2
�
sinh (π (1
−
x)) sin (πy)
A plot of sinh (π (1
the square is approximately
−
x)) sin (πy) is given below. The temp... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
u = u0 on one side, and u = 0 on the other 3 sides. Let α = uE
.
Rotating the plate by 90o will not alter uE
, since this is the center of the plate.
�
Let uEsum be the sums of the solutions corresponding to the BC u = u0 on each of the
�
four different sides. Then by linearity, uEsum = u0 on all sides and hence uE... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
when the hot spot is
placed in the center of the side, i.e. y0 = 1/2.
9.5 Solution to inhomogeneous heat problem on square
We now use the standard trick and solve the inhomogeneous Heat Problem (63),
ut =
u (x, y, t) =
2 u,
u0/ε,
0,
∇
�
u (x, y, 0) = f (x, y)
D
(x, y)
∈
x = 0,
{
y
y0|
< ε/2
}
|
−
otherwise... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
sin (mπx) sin (nπy) e
−π2(m +n2)t
2
where
m=1 n=1
� �
1
1
Amn = 4
(f (x, y)
0
�
Thus we have found the full solution u (x, y, t).
�
0
−
uE (x, y)) sin (mπx) sin (nπy) dydx
10 Heat problem on a circle with inhomogeneous
BC
Consider the heat problem
ut =
2 u,
∇
(x, y)
D
∈
(x, y)
∂D
∈
(65)
u (x, y, t) =... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
for
The problem for uE becomes
0
r
≤
≤
1,
π
−
≤
θ < π.
1 ∂
r ∂r
r
∂wE
∂r
+
1 ∂2wE
r2 ∂θ2 = 0,
�
w (r,
�
π) = w (r, π) ,
−
0
r
≤
≤
1,
π
−
≤
θ < π
wθ (r,
π) = wθ (r, π) ,
−
w (0, θ)
|
|
<
w (1, θ) = gˆ (θ) ,
∞
π
−
≤
θ < π
where ˆg (θ) = g (x, y) for (x, y)
We separate variables
∈
∂D and θ = arct... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
π) ,
22
with eigen-solutions
Hm (θ) = am cos (mθ) + bm sin (mθ) ,
m = 0, 1, 2, ...
The problem for R (r) is
0 = r
d
dr
dR
dr −
�
r
�
2R
m = r
2 d2R
dr2 + r
dR
dr −
m 2R
Try R (r) = rα to obtain the auxiliary equation
α (α
−
1) + α
−
m 2 = 0
whose solutions are α =
For m > 0, r−m blows up as... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
(mθ) + Bm sin (mθ)) = gˆ (θ)
(71)
The orthogonality relations are
m=0
�
π
cos (mθ) sin (nθ) dθ = 0
−π
�
cos (mθ) cos (nθ)
sin (mθ) sin (nθ)
π
−π
�
�
dθ =
�
�
π, m = n
0, m = n
,
(m > 0) .
Multiplying (71) by sin nθ or cos nθ and applying these orthogonality relations gives
π
gˆ (θ) cos (mθ) dθ
(72)
g... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
uE =
u0 +
2π
∞
r m
m=1
�
�
u0 sin (mθ0)
mπ (θ0 + π)
cos (mθ)
−
10.1.2
Interpretation
u0 (cos (mθ0)
(
−
mπ (θ0 + π)
−
1)m)
sin (mθ)
�
The convergence of the infinite series is rapid if r
required for accuracy.
≪
1. If r
≈
1, many terms are
The center temperature (r = 0) at equilibrium (steady-state) is
uE (... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
.
We call these lines the “heat flow lines” or the “orthogonal trajectories”, and draw
these as dashed lines in the figure below.
∇
∇
∇
Note that lines of symmetry correspond to (heat) flow lines. To see this, let nl
u nl.
be the normal to a line of symmetry. Then the flux at a point on the line is
·
Rotate the image... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
2
∞
r
m=1
�
2n−1 sin ((2n
2n
1) θ)
−
1
−
Use the BCs for the boundary. Note that the solution is symmetric with respect
to the y-axis (i.e. even in x). The solution is discontinuous at
, or
r = 1, θ = 0, π
{
π/2. The sum for uE is messy, so we use intuition. We start
with the boundary conditions and use cont... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
flux lines must leave the hot spot and extend to various
θ =
points on the boundary.
−
10.2 Solution to inhomogeneous heat problem on circle
We now use the standard trick and solve the inhomogeneous Heat Problem (65),
ut =
2 u,
∇
u (x, y, t) = g (x, y) ,
u (x, y, 0) = f (x, y)
(x, y)
D
∈
(x, y)
∂D
∈
(73)
us... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
t).
−
uE (x, y).
26
11 Mean Value Property for Laplace’s Eq.
Ref: Guenther & Lee
8.4, Myint-U & Debnath
8.4
§
§
Theorem [Mean Value Property] Suppose v (x, y) satisfies Laplace’s equation
in a 2D domain D,
2
v = 0,
∇
(x, y)
D.
∈
(74)
Then at any point (x0, y0) in D, v equals the mean value of the tempera... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
−π
�
gˆ (θ) dθ
(76)
On the boundary of the circle (of radius 1), (x, y) = (cos θ, sin θ) and the BC implies
that uE = gˆ (θ) on that boundary. Thus, ˆg (θ) = uE (cos θ, sin θ) and (76) becomes
uE (0, 0) = A0 =
We now consider the region
π
1
2π −π
�
uE (cos θ, sin θ) dθ.
(77)
B(x0,y0) (R) =
(x, y) : (x
2
x0... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
�)
(ˆx, yˆ) : ˆx 2 + ˆy 2
1
≤
�
∈
�
27
∇
where ˆ 2 = (∂2/∂xˆ2, ∂2/∂yˆ2). The solution is given by Eqs. (70) and (72), and we
found the center value above in Eq. (77). Reversing the change of variable (79) in
Eq. (77) gives
v (x0, y0) =
π
1
2π −π
�
v (x0 + R cos θ, y0 + R sin θ) dθ
as required. �
For th... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
any disc B(x0,y0)(R) of radius R > 0 centered at (x0, y0),
v (x0, y0) =
v (x0 + R cos θ, y0 + R sin θ) dθ
= Average of v on boundary of circle
π
1
2π −π
�
But the average is always between the minimum and maximum. Thus v (x0, y0) must
be between the minimum and maximum value of v (x, y) on the boundary of the ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
∂D,
∇
∇
0 =
∂D
� �
v
v
∇
·
nˆdS =
� � �
D
Thus, by continuity,
D.
v
|
|∇
= 0 and
∇
2 v +
v
∇
v
2
|
|∇
dV =
v
2 dV
|
D |∇
� � �
�
�
v = 0 everywhere in D and hence v = const in
13 Eigenvalues on different domains
In this section we revisit the Sturm-Liouville problem
∇
2
v + λv = 0,
v = 0,
D
∂D
x ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
��ned on
a volume V with closed smooth surface S.
v
v
∇
·
nˆdS =
∂D
� �
� � �
D
�
2
v +
v
∇
v
∇
· ∇
v
dV
�
In the statement of the theorem, we assumed that v = 0 on ∂D, and hence
D ∇
� � �
vdV =
v
· ∇
−
� � �
D
2vdV
v
∇
(81)
φn}
Let
{
which satisfy
be an orthonormal basis of eigenfunctions on D, i.... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
n m
�
�
� � �
D
2vdV
=
v
∇
−
� � �
D
∞∞
m=1 n=1
�
�
Substituting (84) into (81) gives
λnAnAm
φnφmdV =
� � �
D
D φn
2 dV = 1)
(83)
∞
� � �
A2
n
=1
n
�
∞
−
n=1
�
λn
A2
n
(84)
D ∇
� � �
vdV
=
v
· ∇
−
� � �
D
2vdV =
v
∇
2
λnAn
∞
n=1
�
(85)
Substituting (83) and (85) into (80) gives
R (v) =
� � �
D ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
, so that R (v) > λ1. �
30
�
�
Theorem If two domains D
and D in R2 satisfy
D D
�
i.e., D
D
but D = D,
⊂
then the smallest eigenvalues of the Sturm-Liouville problems on D and D
λˆ1, respectively, satisfy
�
�
�
, λ1 and
λ
1 < λ1
�
In other words, the domain D
smaller eigenvalue.... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
is continuous, since v1 is zero on the boundary of D. Applying the
and function ˆv1 (which satisfies all the requirements
previous theorem to the region D
of the theorem) gives
�
Equality happens only if ˆv1 is the eigenfunction corresponding to λˆ1.
�
λˆ1 ≤
R (ˆv1) .
smallest eigenvalue λˆ1 on D
Useful fact [state... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
+
1
2
y0
�
�
2
The smallest eigenvalue on the circle of radius 1 is λ01 = J0
,1 where the first zero
of the Bessel function J0 (s) of the first kind is J0,1 = 2.4048. Since √λ multiplied
r in the Bessel function, then for a circle of radius R, we’d rescale by the change of
rˆ where ˆr goes from 0 to 1. Thus
variab... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
π
−
π
π
�
−
π
�
R
�
0
=
2
rdrdθ
dv
dr
v2rdrdθ
�
=
6
R2 > λ01
You can show that
and
R (v) =
� �
� �
This confirms the first theorem, since v (r) is smooth on D2, v (R) = 0 (zero on the
�
boundary of D2), and v is nonzero in the interior.
�
32
13.1 Faber-Kahn inequality
Thinking about th... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
1CIRC, as the Faber-Kahn inequality states.
14 Nodal lines
Consider the Sturm-Liouville problem
∇
2
v + λv = 0,
v = 0,
D
∂D
x
x
∈
∈
(89)
Nodal lines are the curves where the eigenfunctions of the Sturm-Liouville problem
are zero. For the solution to the vibrating membrane problem, the normal modes
unm (x,... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
boundary ∂D. Since λmn = λnm, then the function fnm = Avmn + Bvnm is also an
≥
33
eigenfunction with eigenvalue λmn, for any constants A, B. The nodal lines for fnm
can be quite interesting.
Examples: we draw the nodal lines on the interior and also the lines around the
boundary, where vnm = 0.
(i) m = ... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
Since λ31 = λ13 = 10π2/a2, this is a solution to SL
problem (89) on D with λ = λ13. To find the nodal lines, we use the identity
sin 3θ = (sin θ)
4 sin2 θ
to write
−
3
−
�
�
v13 = sin
v31 = sin
v13 −
v31 = 4 sin
sin
sin
sin
�
�
�
�
πy
a
πy
a
πy
a
πx
a
πx
a
πx
a
�
�
�
3
4 sin2
−
πy
a
� �
3
� �
−
sin2
... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
the square plate:
y =
x + ka
y = x,
y =
x + a
−
v31 are the sides and diagonals of the square.
Thus the nodal lines of v13 −
Let DT be the isosceles right triangle whose hypotenuse lies on the bottom hor
v31 is zero on the boundary ∂DT ,
izontal side of the square. The function v13 −
positive on the interior o... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
λ13 of the Sturm-
Liouville problem (89) on Dc.
πy
a
sin2
3
2
−
=
�
�
�
�
.
(vii) Find the first eigenvalue on the right triangle
DT 2 =
0
y
≤
≤
√3x,
x
0
≤
≤
�
1
.
�
Note that separation of variables is ugly, because you’d have to impose the BC
X (x) Y
√3x
= 0
�
�
We proceed by placing the triangle i... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
n2 and look for repeated values:
�
�
n, m
1
2
3
4
5
1
4
7
12
19
28
2
13
16
21
28
37
4
3
28
31
36
43
The smallest repeated value of 3m2 + n2 is 28:
λ31 = λ24 = λ15 = 28π2/3
The linear combination of the corresponding eigenfunctions is itself an eigenfunction
of the SL problem (89) on the rect... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
another method of finding the smallest eigenvalue. The Rayleigh
quotient can help us identify an upper bound.
14.2 Nodal lines for the disc (circle)
For the disc of radius 1, we found the eigenfunctions and eigenvalues to be
vmnS = Jm (rjm,n) sin mθ,
vmnC = Jm (rjm,n) cos mθ
36
with
λmn =
π2j2
m,n
,
n, m = 1... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
, z, t). We
assume the axis of the cylinder is on the z-axis and (r, θ, z) are cylindrical coordinates.
Initially, the temperature is u (r, θ, z, 0). The ends are kept at a temperature of u = 0
and sides kept at u (a, θ, z, t) = g (θ, z). The steady-state temperature uE (r, θ, z) in
the 3D cylinder is given by
2
... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
z)
d2Z (z)
dz2
= 0.
Rearranging gives
1
d
rR (r) dr
dR (r)
dr
r
�
�
+
1
r2H(θ)
d2H(θ)
dθ2 =
1
−Z (z)
d2Z (z)
dz2 = λ
(92)
where λ is constant since the l.h.s. depends only on r, θ while the middle depends
only on z.
The function Z (z) satisfies
The BCs at z = 0, L imply
d2Z
dz2
+ λZ = 0
0 = u (r... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
θ.
We assume g (θ, z) is smooth and 2π-periodic in θ. Hence
H ′ (
π) = H ′ (π),
−
H ′ (
π) = H ′ (π)
−
We solved this problem above and found that µ = m2 for m = 0, 1, 2, ..., H0(θ) = const
and
Hm(θ) = Am cos mθ + Bm sin mθ,
m = 1, 2, 3, ...
Multiplying (93) by R (r) gives
r
d
dr
�
r
dR (r)
dr
−
�
λnr 2 + m... | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
(r, θ, z) =
Im
nπr
L
sin
nπz
L
[Amn cos (mθ) + Bm sin (mθ)]
m=0 n=1
� �
�
In theory, we can now impose the condition u (a, θ, z) = g (θ, z) and find Amn, Bmn
using orthogonality of sin, cos.
�
�
�
39 | https://ocw.mit.edu/courses/18-303-linear-partial-differential-equations-fall-2006/5faa7f7c21719c38fb701bc79ef4a29f_pde3d.pdf |
(R|Ψ) = cos Ψ + sin Ψ = 2 1/2 cos(Ψ - π/4)
2. Identify Sample Space
0
π/2 ψ
3. Probability Law over Sample Space:
Invoke isotropy implying uniformity of
angle
fΨ(ψ)
2/ π
0
π/2 ψ
4. Find CDF
(cid:139) FR(r) = P{R < r} = P{21/2 cos(Ψ-π/4) < r}
(cid:139) FR(r) = P{R < r} = P{cos(Ψ-π/4) < r/ 21/2 }
g(Ψ)
1
r/21/2
1/21/2... | https://ocw.mit.edu/courses/1-203j-logistical-and-transportation-planning-methods-fall-2006/5fb3828ccf1c35471a4ae82804586d50_lec3.pdf |
139) σR/E[R] = 0.098, implies very robust
A Quantization Problem
NYC Marine Transfer Station
Tug
Delivers
LIGHTS
Tug
Picks Up
HEAVIES
LIGHT and HEAVY
Barges Stored
Loading
Loading
Barge
Barge
Loading
Loading
Barge
Barge
Barges
Shifted
By Hand
Or Tug
Refuse
Inflow
λi (t)
Fresh Kills Landfill
Digger
HEAVY BARGES
UNLOA... | https://ocw.mit.edu/courses/1-203j-logistical-and-transportation-planning-methods-fall-2006/5fb3828ccf1c35471a4ae82804586d50_lec3.pdf |
Θare independent.
b) Θis uniformly distributed over [0, 1]
fD,Θ(d, θ) = fD(d) fΘ(θ) = fD(d)(1) = fD(d), d > 0, 0 <θ <1
x
θ
1
K = 0
K = 1
K = 2
1-x
0
1
x
1-x
2
K = 3
3
d
4. Working in the Joint Sample Space
Look at E [K |D = d ]
Let d = i + x 0 < x <1
E [K |D = i + x ] = i (1 - x) + (i + 1) x = i + x = d
Implies E [ K ... | https://ocw.mit.edu/courses/1-203j-logistical-and-transportation-planning-methods-fall-2006/5fb3828ccf1c35471a4ae82804586d50_lec3.pdf |
18.445 Introduction to Stochastic Processes
Lecture 17: Martingle: a.s convergence and Lp-convergence
Hao Wu
MIT
15 April 2015
Hao Wu (MIT)
18.445
15 April 2015
1 / 10
Recall
Martingale : E[Xn | Fm] = Xm for n ≥ m.
Optional Stopping Theorem : E[XT ] = E[X0] ?
Today’s goal
a.s.martingale convergence
Doob’s maximal ineq... | https://ocw.mit.edu/courses/18-445-introduction-to-stochastic-processes-spring-2015/5fe9145062f4c67f4f675b6e18bc2065_MIT18_445S15_lecture17.pdf |
limit.
Hao Wu (MIT)
18.445
15 April 2015
4 / 10
Examples
Example 1 Let (ξj )j≥1 be independent random variables with mean
zero such that ∞ E[|ξj |]
. Set
< ∞
(cid:80)
j=
1
X0 = 0, Xn =
ξj .
n
(cid:88)
j=1
1
(Xn)n≥0 is a martingale bounded in L .
Xn converges a.s. to X∞ = ∞
In fact, Xn also converges to X∞ in L1.
j= ξ1... | https://ocw.mit.edu/courses/18-445-introduction-to-stochastic-processes-spring-2015/5fe9145062f4c67f4f675b6e18bc2065_MIT18_445S15_lecture17.pdf |
n Xk . Then, for all p > 1, we have
||X ∗||n p ≤
p
p − 1
||X
n||p.
Recall Hölder inequality : p > 1, q > 1 and 1/p + 1/q = 1, then
E[|XY |] ≤ E[|X p 1| ] /p × E[|Y q 1| ] /q.
Hao Wu (MIT)
18.445
15 April 2015
7 / 10
Lp Convergence for p > 1
Theorem
Let X = (Xn)n≥0 be a martingale and p > 1, then the following
statemen... | https://ocw.mit.edu/courses/18-445-introduction-to-stochastic-processes-spring-2015/5fe9145062f4c67f4f675b6e18bc2065_MIT18_445S15_lecture17.pdf |
= 1, X
n
n = Πj=1ξj .
1
(Xn)n≥0 is a non-negative martingale.
2 Xn converges a.s. to some limit X∞ ∈ L1.
Question :
1 Do we have E[X∞] = 1 ?
Answer : Set aj = E[
(cid:112)
ξj ] ∈ (0, 1].
1
2
If Πj aj > 0, then X converges in L1 and E[X∞] = 1. (Next lecture)
If Πj aj = 0, then X∞ = 0 a.s.
Hao Wu (MIT)
18.445
15 April 20... | https://ocw.mit.edu/courses/18-445-introduction-to-stochastic-processes-spring-2015/5fe9145062f4c67f4f675b6e18bc2065_MIT18_445S15_lecture17.pdf |
MODULE ConcurrentTransactions [
V, % Value
S, % State of database
T % Transaction ID
] EXPORT Begin, Do, Commit =
CONST s0:S := init()
% initial state
A = S -> [v,s]
E = [a: A, v: V]
H = SEQ E
Y = T -> H
% Action
% Event
% History
% histories of transactions
TS = SET T
XC = (T, T)-> Bool % eXternal Cons... | https://ocw.mit.edu/courses/6-826-principles-of-computer-systems-spring-2002/5ffe1e8aa354be6f61ceb68a116f8392_20slides.pdf |
=ts /\ Consistent(to, xc) /\ Valid(y,to))
FUNC Invariant(com: TS, act: TS, xc, y) -> Bool =
Serializable(com, xc, y)
APROC Begin() -> T = <<
VAR t: T | ~ t IN (active \/ committed) =>
y(t) := {};
active := active \/ {t};
xc(t,t) := true;
DO VAR t’ :IN committed | ~xc.closure(t’,t) =>
xc(t’,t):=true
OD;
>>
... | https://ocw.mit.edu/courses/6-826-principles-of-computer-systems-spring-2002/5ffe1e8aa354be6f61ceb68a116f8392_20slides.pdf |
current) ==>
Serializable(ts, xc0, y0))
CC:
Serializable(current, xc0, y0)
EO: (ALL t :IN act | EXISTS ts | com <= ts <= current /\
Serializable(ts + {t}, xc0, y0))
OD: (ALL t :IN act | EXISTS ts | AtBegin(t) <= ts <= current /\
Serializable(ts + {t}, xc0, y0))
OC1: (ALL t :IN act, h :IN Prefixes(y0(t)) | EXIST... | https://ocw.mit.edu/courses/6-826-principles-of-computer-systems-spring-2002/5ffe1e8aa354be6f61ceb68a116f8392_20slides.pdf |
= h.last.v))
NC: true
FUNC Prefixes(h: T) -> SET H = RET {h’ | h’ M= h /\ h’ # {}}
FUNC AtBegin(t: T) -> TS = RET {t’ | xc.closure(t’,t)}
FUNC IsInterleaving(h: H, s: SET H) -> Bool =
... sequence h is interleaving of sequences from the set s ...
TYPE Lk
Lks
A
= String
= SET Lk
= S -> [v: V, s: S]
CONST
p... | https://ocw.mit.edu/courses/6-826-principles-of-computer-systems-spring-2002/5ffe1e8aa354be6f61ceb68a116f8392_20slides.pdf |
New Bedford Steel Coking Coal Supply Problem 1
New Bedford Steel (NBS) is a small steel manufacturing company. Coking coal
is a necessary raw material in the production of steel, and NBS procures 1.0 - 1.5 million
tons of coking coal per year. It is now time to plan for the 1997 production, and Stephen
Coggins, coa... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
Finally, Steve Coggins needs to keep in mind that capacity for bringing in coal by rail is
limited to roughly 650 mtons per year, and capacity for bring in coal by truck is limited
to 720 mtons per year.
Questions:
1.
How much coal should Coggins contract for from each supplier?
2.
What will be NBS's total cost ... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
.50
80.00
15.066J
3
Summer 2003
Excel Spreadsheet for New Bedford Steel
Optimal Solution
• The third row gives the optimal ... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
Original Value
Final Value
$D$8
$E$8
$F$8
$G$8
$H$8
$I$8
$J$8
$K$8
Amount from Ashley
Amount from Bedford
Amount from Consol
Amount from Dunby
Amount from Earlam
Amount from Florence
Amount from Gaston
Amount from Hopt
0
0
0
0
0
0
0
0
55
600
0
20
100
0
450
0
Constraint
Cell
Name
Ce... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
100 $H$8<=$H$9
0 $I$8<=$I$9
450 $J$8<=$J$9
0 $K$8<=$K$9
Binding
Binding
Binding
Not Binding
Not Binding
Not Binding
Not Binding
Binding
Not Binding
Not Binding
Binding
Not Binding
Binding
Not Binding
Binding
Not Binding
Not Binding
Not Binding
Not Binding
Binding
Not Binding
0
0
0
145
125
55
60... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
$C$16 Rail
$C$14 Union
1225
0
720
505
125
61.5
3
-1
0
0
1225
0
720
650
0
5
20
20
1E+30
125
25
100
3.33
145
1E+30
15.066J
6
Summer 2003
Sensitivity Report : Notes for NBS Case Discussion
Shadow Price for a constraint is how much the objective function for the ... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
your economic
intuition to assure that you are making the right interpretation. Also, different solvers
may refer to dual prices, rather than shadow prices: they are the same.
15.066J
7
Summer 2003
Now, let's consider the volatility constraint from the NBS case. Suppose that we re-
write the constr... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
for 1 ton of volatile matter).
We can reinterpret this in terms of the volatility content of coal. Each percentage point
of volatility will supply 0.01 tons of volatile matter per ton of coal. Since the cost to
supply 1 ton of volatile matter is $300, each percentage point of volatility has a value of
$3 per ton of... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
goes
down, how much of a penalty should NBS insist on in their contract?
15.066J
9
Summer 2003
New Bedford Steel Coking Coal Supply Problem - Addendum
From the optimal solution we can use the shadow prices on the resource and
quality constraints to infer an ex-post imputed cost... | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
, F and H are at their lower bound of 0.
The difference between their imputed costs and $61.50 (shadow price for the supply
constraint) is their reduced costs.
15.066J
10
Summer 2003 | https://ocw.mit.edu/courses/15-066j-system-optimization-and-analysis-for-manufacturing-summer-2003/60367b40dc46191eb2ff5a1d44b8b66e_ses1_freund.pdf |
Lecture # 22
Date: 4/30/09
8.592J–HST.452J: Statistical Physics in Biology
1 Kinetics of protein–DNA interaction
1.1 Reaction Kinetics
1 The rate of change with time of the concentration of a protein–DNA complex is the sum
of two terms. A positive contribution due to complex formation between a previously free
specific ... | https://ocw.mit.edu/courses/8-592j-statistical-physics-in-biology-spring-2011/6039e032dce5df28031d2100fe2fe33f_MIT8_592JS11_lec19.pdf |
,
(2)
DNA]) as the characteristic time scale for a free
where we have identified τ = 1/(ka[P
repressor to locate the operator sequence. For the measured value of ka, this search time is
of order τ
0.1s.
|
∼
1.2 Debye-Smoluchowski theory
In this section we will compute the on–rate ka. The classical theory of the on–rate ... | https://ocw.mit.edu/courses/8-592j-statistical-physics-in-biology-spring-2011/6039e032dce5df28031d2100fe2fe33f_MIT8_592JS11_lec19.pdf |
and C(b) = 0 (because diffusing particles disappear
at r = b). Spherical symmetric solution is
2C = 0
∇
(4)
C(r) = C0
1
(cid:20)
b
r
,
(cid:21)
−
(5)
where C0 = CR/(1
the radial inward direction is ~J =
equals:
b/R)
−
≈
CR for b
≪
D3∇
−
I = J(r)4πr2 =
−
R. The diffusion current density of proteins along
D3bC0/r2 ˆer, so ... | https://ocw.mit.edu/courses/8-592j-statistical-physics-in-biology-spring-2011/6039e032dce5df28031d2100fe2fe33f_MIT8_592JS11_lec19.pdf |
combination of 1D (sliding) and
3D (jumps) diffusion to quickly find the target site on the DNA (Figure 1). Proteins are able
TF
Figure 1: Schematics of 1D/3D search for target site on the DNA. Dashed lines represent
3D diffusion trajectories and thick lines are 1D sliding footprints.
to bind to any site on the DNA and th... | https://ocw.mit.edu/courses/8-592j-statistical-physics-in-biology-spring-2011/6039e032dce5df28031d2100fe2fe33f_MIT8_592JS11_lec19.pdf |
∞
NR =
NRq(1
NR=1
X
−
3
q)NR−1 =
1
q
=
M
n
(8)
The average search time for protein to find the target site is:
ts = NR(τ1 + τ3) =
M
n
(τ1 + τ3),
(9)
where τ3 is average time of 3D jump.
In reality sliding events don’t take fixed amount of time. Protein detach from the DNA
with rate k(ns)
d = 1/τ1 and time of each slidin... | https://ocw.mit.edu/courses/8-592j-statistical-physics-in-biology-spring-2011/6039e032dce5df28031d2100fe2fe33f_MIT8_592JS11_lec19.pdf |
h
ts
h
i
ts
h
i
ts
ts
h
h
i
i
=
=
=
=
∞
NR
NR=1
X
NR
NR
NR
h
h
h
i
i
i
τ3 +
τ3 +
h
(cid:0)
R
NR
[τ1,i + τ3]
!
*
i=1
X
∞
p
NR−1
q(τ1,NR)
[1
q(τ1,i)]
+
−
i=1
Y
)NR−2 [
h
i
(NR
1)
q
h
i
(1
−
q
− h
NR=1 (cid:26)
X
NR
h
(cid:26)
+ τ3
τ1i
[
h
i
=
τ1i − h
Mb
2√D1τ1
qτ1i
] +
NR
qτ1i
ih
h
(cid:27)
(cid:1)
It is interesting to ... | https://ocw.mit.edu/courses/8-592j-statistical-physics-in-biology-spring-2011/6039e032dce5df28031d2100fe2fe33f_MIT8_592JS11_lec19.pdf |
binding energy Ens since this interaction is predominantly electrostatic. One would
expect that at standard physiological conditions τ1 is close to the optimal value τ3, but it
turns out that protein spends more time sliding than jumping τ1 > τ3. Typical measured
10−3s, while we can estimate the typical jumping time
sl... | https://ocw.mit.edu/courses/8-592j-statistical-physics-in-biology-spring-2011/6039e032dce5df28031d2100fe2fe33f_MIT8_592JS11_lec19.pdf |
Chapter 11B
Design of Seals
Design of Face Seals
Wear of Face Seals
(From Ayala, et al. 1998)
Diagram removed for copyright reasons.
See Ayala, H.M., Hart, D.P., Yeh, O.C., Boyce, M.C. "Wear of Elastomeric
Seals in Abrasive Slurries", Wear, 220, 9-21, 1998.
Percentage of lip worn as a function of the
number... | https://ocw.mit.edu/courses/2-800-tribology-fall-2004/605d69102d68f79501ee511dae851cf7_ch11b_seal_des.pdf |
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