week 9 - programming iii today: – another loop option – a programming example: tic-tac-toe...
Post on 18-Jan-2016
218 Views
Preview:
TRANSCRIPT
Week 9 - Programming III
Today:– Another loop option– A programming example: tic-tac-toe
Textbook chapter 7, pages 213-216, 219-226
(sections 7.4.2, 7.7)
Quiz on Thursday – meet in 112 Kirk.
Longer Running Loops
for loops repeat a fixed number of times:
for variable = {array of length n}
{commands}
end
and break can be used to stop earlier.
Question: How about repeating “until done”? Run as long as is needed.
Answer: MATLAB’s “while” loop:
while expression
{commands to be repeated as long
as expression is true}
end
Prior example – compounded interest untilthe amount doubles:
value = 1000;
for year = 1:1000
value = value * 1.08;
disp([num2str(year),' years: $ ',num2str(value) ])
if value > 2000
break
end
end
for loop
terminated with break
Expected output:
while version
format bank
value = 1000;
while value < 2000
value = value * 1.08;
disp(value)
end
Example – Collecting and storing data until a zero is entered:
x = [ ];
new = 1;
while new ~= 0
new = input('enter value ');
x = [ x, new ];
end
x = x(1:end–1)
empty array
to drop the zero
initialize
Example – Getting valid keyboard input:
E.g. forcing the user’s input to be between 0 and 10:
x = –3;
while ( x < 0 ) | ( x > 10 )
x = input( 'type a value ' );
end
or:
x = input('enter value ');
while (x<0)|(x>10)
disp('invalid choice');
x = input('enter value ');
end
disp('finally!');
Example – computing pi:
...13
4
11
4
9
4
7
4
5
4
3
44
Example – “infinite” Hi-Lo:
numb = round (10*rand(1)); done = 0;while ~done
guess = input('guess');if guess = = numb disp( 'You got it !!!' ); done = 1;elseif guess > numb disp('too high')else disp('too low')end
end
initialization
single guess
loopcontrol
Nesting of while loops
while expression1 {outer loop commands} while expression2 {inner loop commands} end {more outer loop commands}end
these can also be more than 2 levels deep
Example of Programming: tic-tac-toe
Play tic-tac-toe, human against human:– Track moves– Show board– Recognize end of game
3-by-3 array for the board:– Empty cell = 0– X = +1– O = – 1
Game end:– Winner if row, col, or diag sum = +3 or –3– Draw is no zeros left
Loop for game:– Initial move (X) plus 4 pairs of moves– Break if winner
1. Initialization, including graphics
2. Get X’s first move
3. Loop 4 times:– Get O’s move, check for win– Get X’s move, check for win– Break on victory
4. Check for draw
Program flow:
Flowchart:
Initialization
Get X move Get O moveO
wins?
Get X move
Xwins?
GameOverDraw?
Yes
YesYes
No
No
No
GameOver
GameOver
Program Outline:
Program Details: Initialization
Board Graphic
Get and Show First Move (X)
Start Loop with the Second Player
Check for Victory by O
Finish Loop with the First Player
Check for a Draw
Typical Output
Semester Project Intro
CARBURIZING GEARS – Diffusion of atomic carbon into steel allows very
hard iron carbides to form near surface. These “cases” are hard and very wear resistant so are used to make gears.
– Project is to model this for a variety of different conditions.
Example of Diffusion Leading to Failure
Steel plate with a hydrogen blister in it.
H+H H2
Atomic hydrogen from surface moves through steel until it combines to form molecular hydrogen which
cannot move in steel. Pressure builds forming blister
Stress Strain Curves
The load extension data can be transformedinto Stress Strain data by normalizingwith respect to material dimensions.The stress is the load divided by the original cross sectional area.
= L/As – stress , units MPa, or psi or ksiL – load appliedA – original cross sectional area
The strain is the increase in normalized by the original length.
e = l/le – strain – dimensionless (in/in)l – increase in lengthl – original lengthStrain is often given in percent so x100As the normalizations are by constantsthe shapes of the curves stays the sameBuilds on mechanical behavior from EGR 105which was elastic deformation
Stress
Strain
Failure Point
EGR 105 Range
De-Carburization
Decarburization at 1200F after quench crack in material. The crack left enough open surface for the carbon to diffuse out and leave a ferrite layer either side of the crack.
Diffusion – Basics.
Atomic carbon is diffusing through steel Diffusion follows Arhenius equation so activation energy
controlled
D = Do exp (–Q/RT) –create as a function? D – diffusion coefficient (m2/s) Do - temp independent pre-exponent (m2/s) Q – activation energy (kJ/mol ) R – gas constant 8.31 J/mol-k T – absolute temp (K) Temperature dependent.
DIFFUSION- Units
R - 8.31 J/mol-K; 1.987 cal/mol-K; 8.62 ev/atom-K
Q – J/mol; cal/mol; ev/atom. (1ev/atom = 23kcal/mol)
Non Steady State Ficks 2nd Law
Non Steady State – Concentration changes at position x as a function of time, eg Cu Ni
c/t=D(2C/x2) Ficks 2nd Law
Solution to this :-
Cx-Co/Cs-Co= 1- erf(x/2((Dt)-1/2))
Cx – concentration at depth x at time t, wt%
Co – concentration in average in bulk, wt %
Cs – concentration at surface, fixed with time t, wt%
Co- concentration in average in bulk, wt%
Erf – error function – look up in tables.
x – distance below surface, m
D – diffusion coefficient, m2/s
t – time in seconds
Diffusion Rates
Solute Solvent D at 500 C Dat1000 C Carbon BCC iron 5x10-12 2x10-9
Carbon FCC iron 5x10-15 3x10-11
Iron BCC iron 10-20 3x10-14
Nickel FCC iron 10-23 2x10-16
Silver Silver Xtal 10-17
Silver Silver Grain Bound 10-11
Interested in carbon in iron. First assignment – need to be able to find D at any temperature to use in
Fick’s second law . Thursday lab assignment - use Arhenius equation as a function? Look at week 5 notes for plot of D v1/T.
Example
Time for the carbon concentration at 500C to reach half way between the steel composition level and the external level at 0.5mm below the surface.
Using Fick’s second law Cx-Co/Cs-Co= 1- erf(x/2((Dt)-1/2)) The left hand side is 0.5. 0.5= 1- erf(x/2((Dt)-1/2))
Rearranging 0.5 = erf(x/2((Dt)-1/2)) 0.5 = erf(0.5205)
So 0.5=(x/2 ((Dt)-1/2))
Dt = x2
t=x2/D =(5x10-4) 2/(5x10-12)
t= 25x10-8/5x10-12
=5x104sec =13.8 hours
Overall Project
A program that will take input such as temperature, steel composition, and carbon concentration in the surrounding environment then as output be able to graphically show carbon concentration profiles in the steel as a function of time and treatment temperature. In between the input and output is the program in “Matlab”
An oral report using Powerpoint. A two page written report per team.
Teams
Vertical – have a team leader responsible for all organization of team and output. The leader assigns work to team members. Team members report only to team leader. Team leader must ensure assigned tasks are completed by team member. Allows for individual meetings.
Teams
Horizontal – all members responsible for organization and output. Work assignment is a group activity. Task completion could be group as well. All meetings team meetings.
Which team depends on personnel. You should decide which type of team.
STRATEGIC PLANNING?
Once you decide on team type, develop a “Strategic Plan” – What are the teams objectives? How are you going to achieve them? Write it out so the team can follow it.
Companies and other organizations have “Vision and Mission Statements” as well a strategic plans.
Meet next Tuesday with strategy and first assignment from Thursday lab complete.
top related