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Unformatted text preview: EXAM 2 preview/review CHE 361 Winter 2012 Remember...... Midterm # 2 is 10  11:50 am Thur. Mar. 1, 2012 in Kearney 212.
Bring your own (Textbook+), paper, pencils, calculator with charged batteries, etc.
(Textbook+) = SEMD3, KLL handouts, notes and your own HWs. You must show your work
and put FINAL answers in the boxes or spaces provided !! Numerical answers must not be
“expressions”, e.g. x not = 37 π / 44 but rather x = 1.49 if required “to 3 significant figures”.
NEW TOPICS  exam may include previous topics as well as new ones !
Review = Chap. 4: Derivation of G(s) from nonlinear ODEs, example = Bioreactor.
Chap. 5: Familiarity with "simple" (no zeros) firstorder and secondorder dynamics, explicit
availability of responses to standard inputs of step, ramp and sinusoidal functions
of time. Standard parameters of TF models, i.e. zeta as damping coefficient, tau
for firstorder and secondorder systems (over, critically and underdamped
systems).
Chap. 6: More complex G(s) => TFs with more than two poles, zeros, and time delay.
"Story" problem descriptions of dynamics / rate of accumulation: steadystate relationship and
description of dynamic changes and functions of time. Solution of nonlinear
dynamics using linear approximation (transfer function model) theory.
Some familiarity with the use of MATLAB and Simulink software tools for CHE 361 problems,
including step2g and numerical methods ode45 to solve ODEs, e.g. be able to
solve a nonlinear ODE using Euler method using a calculator for a specified step
size and for a specified number of steps.
Chap. 7: Identifying transfer function models from step response data, theory and "noncomputer" methods for 1st and 2nd order systems, step2g software for leastsquares fit of G(s) => data file format (3 columns) and use, specifications of
parameters, interpretation of program output and results.
Chap. 5,14: Frequency Response  Given G(s): physical meaning of AR and phase angle,
shortcut method and complex numbers / algebra, "Bode plots" including time
delay, the "Gplane plot" of Real and Imag parts of G ( jω ) as frequency changes
is called a "Nyquist diagram". Components of overall AR and phase angle due to
simple “factors” of G ( s ) poles and zeros  handouts on frequency response.
Use of CHE 361 / MATLAB frequency response data file format (5 columns)
and programs: freqg, chebodei, chebode2i and plots, and pulsec for
pulse experiment analysis.
See back side for more !! → “SOME” OF THE TYPES OF PROBLEMS .....
1) Be able to identity type of transfer function model from a process step response curve or
datafile and vice versa: solve for y(t) given G(s) and size of step, solve for G(s) given y(t)
and size of step.
2) Be able to switch among any of the possible "forms" of G(s). Some examples are:
 standard form (coefficient of lowest order in s = 1)
 factored form (equivalent to coefficient of highest order in s = 1)
 specification of location of poles and zeros along with gain
 given values of standard parameters ( K, θ, τ = 1st or 2nd, ζ and τz )
Standard form 2(0.2 s + 1)
4(0.2 s + 1)
0.8( s + 5)
==
Factored form
2
2
0.5s + 1.5s + 1 s + 3s + 2 ( s + 2)( s + 1) Gain = 2, Poles at s = 1, s = 2, Zero at s = 5.
3) Be able to derive the overall transfer function between an output and input from a
component block diagram arrangement: series, parallel, feedback arrangements as shown
in Chap.6 and inclass notes for handout “Interacting Tanks  Block Diagrams” (feedback
loop in block diagrams).
4) Given a set or single nonlinear ODE, be able to linearize (when necessary) terms to derive a
transfer function model of the process dynamics. Be able to solve a firstorder ODE
problem using the transfer function approach. Describe differences between linear and
nonlinear model predictions of responses to step changes in input. Be familiar with
Bioreactor project.
5) Be able to numerically solve ODE(s) using Euler's method and a calculator  understand
effects of the choice of step size on the accuracy and stability of numerical solutions of
ODE(s).
6) Be able to interpret physical storytype problems which depend on frequency response
interpretation, such as EXAMPLE 5.6 ( page 85 SEMD3) and EXERCISE 14.3 (page 268
SEMD3).
7) Given a transfer function, use the shortcut method to calculate the amplitude ratio (AR) and
phase angle (PA) for a specific frequency. This requires calculations using complex
numbers and their interpretation. Be able to calculate the frequency response of a
complex transfer function based on its "parts", as discussed in the "components" handout.
8) Given a BODE plot, determine an appropriate form/type of transfer function and determine
numerical values of simple parameter problems, e.g. K value or time constant and
damping coefficient for 1st or 2nd order systems from AR/PA plots/data. ...
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 Winter '08
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