MECH 430 Final, Spring 2015

AMERICAN UNIVERSITY OF BEIRUT MECH 430 Instrumentation & Measurements Final Exam — May 19, 2015 Time Allowed: 2.5 hours Closed Book Allowed: cheat sheet, a non-programmable calculator. Test Rules Test period = 150 minutes. Explain everything in order for me to give you part marks If you are stuck on a part SKIP it and then come back later. Sharing calculators is not allowed. Name: Daniel... Kachahonccccccce Student Number: ...... DoILO9C7%Z.S....... eae Lee Problem 1 Problem 2 Problem 3 Problem 4 Problem 5 Problem 6 Problem 7 Total MECH 430 Instrumentation & Measurements — Final (Spring 2015) Problour time rou Wind ote HEMET eI ED peal VY Nowe tae apyatig atin Kor tho op aap atten than WHT atin an P y Nera thes ae ign |, \)\ i’ Wer veg! a, SY WAY hee ot tine ae CPO AHAR Taper Tange! \\\ . mi rn ree vanel oul owt vay ll lee VD Tie Figsuiiw Dacha athcrvan he OPP CH What Ge the dae ot the offer null cannes tote? sn mer ‘ J Ls ee ewe io \' ’ *. meraty | |, td Steet o ‘ ' CI ho O10 pee ree te ew Fat hose eegiste Wha \ye olfee! pines ‘ Micthaty Wee ctat ow & Mea ‘ ia ' ‘ Scanned by CamScanner 4) What is the difference between active and passive filters? Name two advantages of active filters. ‘ Fr . ‘hv \ achive Pilkers VR ape “t a lon a | ¢ Seu fesichs and ww ds ths Uv hike ‘a ike only vse C L awd R- a ven tages’ - can geben goin Pl il . has an infinite = ahpslringe anes. \ \ 5) Define the cut off frequency of filters. ewttes - 6 the freq. avrvde the —_ "S re “ As max nol oh ie OM "te = \ \ 3 6) What is the difference between earth ground and reference ne J ; - mae {| MECH 430 Instrumentation & Measurements — Final (Spring 2015) Scanned by CamScanner 7} Describe ground loops and how can they be avoided. teu loogs a he Cop sed ronne cH , a pounds lp no los prcalarn 7 - ane ee oe 28 $) Long wires act as antennas and will pick up stray signals from ol electrical fields. Describe how to reduce their effect. an yrs } fx c shiel the enttnncs-: 2 Coak wy ay § ‘i CON of carling | the shed oy SA QANo 7. 4 ter be pen & Row wiecke Fk re Be Tha \ 9) What are the two methods to describe resolution of analog to digital converters? fe 50] \ 1S the nue ber Le toed hag the ADC. Ullor \ or itis 7 sep site os — bts . Fee) lure TET VQ = ly a FS volte ~ Vit VL . greellest | ye ee >t cn bit 4 4 value - Reast sigh Vy-Ve = A yo Ro? MECH 430 Instrumentation & Measurements — Final (Spring 2015) “Scanned by CamScanner 11) Aliasing is the misinterpretation of a high frequency signal with alow frequency one. Hav can aliasing be avoided? a [£ : F ) 5 U5: +h, hished Myo. ‘5 Wqhe than Fe, runce He WY Freaaen ") ‘a Pre $1 i ushion. 12) What is one advantage of non-inverting amplifiers over inverting amplifiers? What is one advantage of difference amplifiers over inverting and non-inverting amplifiers? if . ' ro [eo haar as at _rovineehny Dear = hes rin Petes Toh in he Yr 4 ‘ © es\sfolS Ahan os \ te noioQ > Aerene anaplihers can . chai m4 resulting oe fhe J ingl 13) What are the main advantages atthe instrumentation amplifiers over other types of amplifiers? lye ) bes eheike in(ah mpedenex 14) How does the dependency of the op-amp gain on the input signal frequency affect the performance noting that the derived inpuvoutput relationship of the inverting amplifier is independent of op-amp gain? How can this gain be estimated knowing the operating frequency? decree Cs Beading At high fre ty, ct ise 7 than whet . Hevackicly oe deer arp f { * L oe et ae dd iquater 09 Onp uct” ps Al (Ta) » 4 v b re dovet * the gain fo Ke end f of oo eee She aN MECH 430 Instrumentation & Ps i F ha (Spring 2015) O Rh f 1S) To build a band pass filter, we can cascade a low-pass and a high-pass active filter, Draw the diagram and spegity the condition on the cutoff frequencies of cach filter. 4. 16) Why a band stop filter cannot be built from cascaded low-pass and high-pass filters? (ce cnsende 2 Lpond tt? fillen- _ tow foeguan t's the Siqnel wil be a tlenva nue the 3! we, \ the HP filles. At hy. Frgmsnes! : - OY tel bby fhe LY fle 17) (4 marks) Indicate the type of the filters shown in the figures below. You do not need to justify your answers.. Write down your answers on the answer booklet associating the letter labeling the figure. $ 0 Cp OSC “ i [ace WW “f° c ete Ol > L Loy, £— oj>6 T — y L nyv ey) » tt_-—Wwvs—_ tN < ° (d) Hy h poss MECH 430 Instrumentation & Measurements — Final (Spring 2015) Scanned by CamScanner MECH 430 Instrumentation & Measurements — Final (Spring 2015) Scanned by CamScanner Problem 2 (5 marks) (uncertainty analysis) For a displacement transducer having a calibration curve y=KE, estimate the uncertainty in displacement y for E=5.00V, if K=10.10 mm/V with u.=+0.10 mm/V and uz=20.01 V at 95% confidence. pete” (OLN: Fe iy (By BY ts a ANN ae Uy . \| [lol + + ((oo-0)) = 7! +95) wmpAsy 5 + 50.50 20. a Problem 3 (10 marks) (uncertainty analysis) The area of a flat, rectangular parcel of land is computed from the measurement of the length of two adjacent sides, X and Y. Measurements are made using a scaled chain accurate to within 0.5% over its indicated length. The two sides are megsured 3 wale es with the following = 1L34— War, results: \ En X=556m Y=222m dy> 2 a 5,=53m S,-2im By Lt =D. B55 a ry v=8 v=7 Estimate the area of the land and state the confidence interval of that measurement at 95%. ~ XY-= 123432 wr: c= > S. . “S.. eto <s : : Vz z —— ts CYS: KS) = NGG (C020) = 569.2 “\\ b- Te cy -\(@x30) 6 («6 3B) ~ a 363. (\\se)* AS) e & GY) CEE Gy, ES Vy V5 V = 4 MECH 430 Instrumentation & Measurements — Final (Spring 2015) “Scanned by CamScanner « _— x 4 . os ean 556 (0,555) ) 5 efor 7 )\ oa) 22 - = Ss HO — “7h Tho Vy z ~tye , 4s") : re L vp " o c= Cpe —— osu), & a a Ln eg 47) 2 67: MECH 430 Instrumentation & Measurements — Final (Spring 2015) scanned by CamScanner Problem 4 (10 marks) (system response) A single-loop RCL electrical circuit can be modeled as a second-order system in terms of current. Show that the differential equation for such a circuit subjected to a forcing function potential E;(t) is given by: @I dl 1, dB R +h = Bee (yD Lip thatol =a Lut ‘ cia 4) 2 a, Ao 1. Determine the natural frequency, the damping ratio, a to. gain for this system. 2. For a forcing potential of a step input of 0.5V, determine-at-whi Ch frequency the system will oscillate. Use L=2H, C=IpF, and R = 10,0002 3. Plot the estimated response of the system dt L (tae pa = ot@ket Ey 4 Pi. b Ee 3 gp eae Dh abi 4 @ate LAT, TL at dv at a LY Ge At D> HA aa \ore 2. AE = O. sine ih aslep. " ac LiF Since up S = abe fans i wall ocer" _~ Sant mid % 6cl4): fein we) = S =. OMT j S. 35 AA MECH 430 Instrumentation & Measurements — Final (Spring 2015) Scanned by CamScanner