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Unformatted text preview: BB 350 EXAM III 9 APRIL 1998 Name: 50' u'i‘. [005 ID#: Section: DO NOT TURN THIS PAGE UNTIL YOU ARE TOLD TO DO SO _Problem Weight Score Total 100
_ Test Form A This test consists of four problems. Answer each problem on the exam itself; if you use additional
paper, repeat the identifying information above, and staple it to the rest of your exam when you hand it in. In order to receive credit, you must show all your work. Problem 1: (25 points) The block diagram of a speed control system for an electric train is shown below. controller am lifier train motor speed
Y(s) 1. (10 points) Find the closedloop transfer function Y(s)/R(s) in terms of the transfer functions 0(a) and 6(3) and the constant gains K and K5. 2. (8 points) Suppose that all components of the control system are speciﬁed except for the ampliﬁer gain K , and that the resulting closed—loop transfer function is Y(s) _ K
Iii—(5). — W' Determine the range of K for which the closedloop system is BIBO stable. 3. (7 points) Using the system transfer function in part 2, and assuming K is set so that the system is
BIBO stable, ﬁnd an expression for the steady—state speed of the train in terms of the ampliﬁer gain K when a unit step input r(t) = u(t) is applied to the closed—loop system. 1. Y“) = K recs) 6C9 Ems} — k5 no] meI + Ksk ccs\GCs\:) = scenes» Ms) For. (3‘60 étwblll'Lb[J the palms
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s YLS) élgo Shut) Po‘es 'LLEL .02.“: qu42. 7‘1er mean! Problem 2: (25 points) The electrical network shown below has an input f(t) and an output y(t). 2 Q ‘ U 1. (10 points) Show that the transfer function of the network is Y(s) _sa+2s+1
F(s) _ sz+4s+4I In order to receive credit, you must show all work required to ﬁnd H(s).
2. (5 points) What are the pole(s) and zero(s) of the transfer function H (a) ?
3. (10 points) Given f(t) : u(t), ﬁnd the zerostate response y(t) using Laplace transform techniques. 1, 04% Kw. ,4: noﬂu 14 awe: \J YCs‘r PCs) MED. + ﬁli— + ((5) = o
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H“) ch Lt: "’ "E's—Ti: + ‘ 2H7. (swat—H 4» 25+? Problem 3: (25 points) 1. (10 points) Is the following signal
f(t) = 2cos(31rt/8) + sin(3t/4) periodic (justify your answer !) '? If so, ﬁnd the period.
2. (6.points) Consider the function f(t) : ellw‘l' + 450}. (a) (2 points) Is the function f(t) odd, even, or neither even nor odd ? To receive credit, justify
your answer. (b) (4 points) Express the function f(t) as the sum of an even function f,(t) and an odd function
fa(t). Simplify your expressions for f,(t) and f,,(t) as much as possible. 3. (9 points) The output of a. rectiﬁer circuit is a. periodic voltage y(t) whose period is T and trigonometric
Fourier series coefﬁcients are 2
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5,, = 0. Is the periodic signal y(t) even, odd, or neither even nor odd ? Justify your answer. I. p('t +T) =5 2605 + 4 5m (.374; .4. In anger '5 ob‘lu‘m “F H: +7) "'—v ‘Fbr‘ um "bJ we. need
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[5 —5 —3 —1 1 3 5 1. (2 points) What is the period T of the signal ?
2. (6 points) Find the average value of the periodic signal 3. (12 points) Find the trigonometric Fourier series coefﬁcients on. Simplify your expression for 0,,1 as
much as possible. 4. (5 points) Find the trigonometric Fourier series coefﬁcients b”. Simplify your expression for b" as
much as possible. i, 143' Jimkn in 1‘6 0'50"?) .172. Z I S?— 10' ...
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This note was uploaded on 03/17/2008 for the course EE 350 taught by Professor Schiano,jeffreyldas,arnab during the Fall '07 term at Penn State.
 Fall '07
 SCHIANO,JEFFREYLDAS,ARNAB

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