Transcript Precedence - Chemical Engineering

EGR 106 Intro to Engineering II
• Engineering problem solving using MATLAB
• Text: Amos Gilat, MATLAB An Introduction with
Applications, Wiley 2004 ISBN 0-471-43997-5
Instructor EGR 106 Section 7
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Richard Brown, Department of Chemical Engineering,
110 Crawford Hall
Office hours Tue-Thur 11 -12pm
[email protected]
874-2707 (Office)
Grading
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Attendance
15%
IMPORTANT SIGN IN ALL CLASSES!!!!
Homework
15%
3 Quizzes
40%
Team project
30%
Homework
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15% of your grade
No partial credit
Done during lab.
If you can not solve a problem, get help.
10 point scale for each assignment
Late home work penalty is 2 points
Not accepted after one week.
Engineering Computer Lab - ECL
• To use the ECL you will need the username
and password provided to you by the
College of Engineering when you started.
• If you cannot remember your username and
password for access to ECL computers, stop
by the HELP desk TODAY after class and
request one be issued to you. You will need
it for next Tuesdays class.
Computation
• What is computation?
• Examples:
3+2
tan 40o
• Computation = “transformation from one or
more inputs to an output”
Computer Computation
• Very fast at arithmetic operations
• Large numbers of repetitive operations quickly
• Algorithms = computer programs
– Need to understand what computations are “simple”
for the computer
– Need to write a clear set of directions to be followed
– Build more complicated computations from
intermediate ones
Algorithms
• Definition: “a set of directions for carrying
out a computation in terms of other, simpler
computations”
• “Simpler computations” = ones that we
already know how to do
MATLAB – What is it ?
• Name is from matrix laboratory - uses matrices or
rows and columns of numbers.
• Powerful tool for
– Computation and visualization of engineering and
science mathematics
– Communication of ideas
– Programming:
• Built-in editor, debugger, and help
• Many predefined functions (grouped in toolboxes)
• Interpreted or compiled programs
The Command Window
• Command prompt >>
• Basic math operations are available:
addition + subtraction –
division /
multiplication *
exponentiation ^
“enter” key “executes” or “runs” or “invokes”
the operation
• Operator precedence: PEMDAS
5–4+3^4/(3–1)=?
Arithmetic Operations
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Addition
Subtraction
Multiplication
Right Division
Left Division
Exponentiation
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^
2+2
3-2
3*6
7/3
7\3 = 3/7
2^3 = 8
Precedence
• Precedence is the order operations are
preformed, remember PEMDAS
• (3^2) anything in parentheses is done first
• 5^2 exponentiation is next
• 2*2 or 10/5 multiplication or division next
• 1+1 or 5-3 addition or subtraction next
• Operations are done from left to right
Precedence Example
• 2^(6/2) = 2^3 = 8
• 2^6/2 = 64/2 = 32
• Remember computer does what it is told
rather than what you hope it should do.
Some Syntax
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Assignment operator =
> x= 1;
> x = 2*x+1;
The value of x is 3
Remember when programming that
assignment operators can be changed as
a result of program actions, so be
careful assigning constants.
Predefined Variables
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ans
pi
eps
inf
i
j
NaN
p
2^(-52) about 2.22e-16
1/0
sqrt(-1)
Same as i
Not a number 0/0
Some Functions
• Elementary Math, sqrt(x), exp(x), etc.
• Trig, sin(x), cos(x),
x is in radians
• Rounding functions , round(x), etc
DIFFUSION
• What is diffusion? Transport of one atom, ion or
molecule through a medium.
• Applications of Diffusion.
• Fuel Cells
• Drug Delivery
• Strengthening Metals.
• Structural Failure.
• Computer Manufacture.
• Polymer and paint breakdown.
• Separations
FUEL CELL Proton Exchange
Membrane (PEM Cell)
Proton Diffusion
2H ++ O 2-  H 0
2
Diffusion controls start up time and current produced
Demonstrations
• Matlab has a number of demonstration
programs.
• Often helpful to run then and also examine
the programs – shown in command window.
May provide some programming tips!!!