Passage 1: Passage 2:

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1 مدرسان شريف رتبه يك كارشناسي ارشد سو الات آزمون سراسري 85 زبان عمومي و تخصصي eading Comprehension Direcion: ead he following eigh passages and answer he quesions by choosing he bes choice among ), (), ), or ). Then mark he correc choice on your answer shee. Passage : Elecriciy s green roos run deep, saring wih one of is earlies applicaions: he incandescen lamp. The lamp was a welcome advance, and no jus for is ligh. In 89, archiec Frank T. Len described elecric incandescen ligh as he acme of all mehods of lighing never impairing he air in a room. Elecric ligh was a clean safe alernaive o he gas ha was being used o ligh businesses and homes. Gas was sooy, consumed oxygen, and released carbonic acid ino he air, damaging books curains, and carpes. Smoke, ashes, and cinders are unknown because elecriciy is used now for which formerly fires had o be buil, novelis Solomon Schindler wroe in 89. Tha was no enirely rue; coal-fired saions sill generaed mos of he elecriciy. Alhough generaing power cenrally back hen does no qualify as green by oday s sandards, i was less harmful o he environmen ha he scores of dispersed coal- burning furnaces would have been. In he 9 h cenury, facories were clusered in ciies, insead-as nowadays-ouside of hem, so clean power sources were a civic necessiy. Seam replaced waer power as he primary source of energy used by indusries he Unied Saes and Europe, and ha resuled in grimy, smoke- shrouded ciies. - Why was an incandescen lamp considered o be Green in he early days of elecriciy? ) Because he lamp was he acme of lighing echnology. ) Because he new lamp consumed oxygen and carbonic acid. ) Because Gas lamp soo arnished curains, books, and carpes. ) Because he lamp replaced lighing mehods ha pollued living areas. - I can be deduced from he ex ha. ) Grimy and smoke shrouded ciies are unknown o well developed counries ) Nowadays smoke, ashes and cinders are unknown because elecriciy has replaced hem ) Elecriciy generaion was no necessarily Green given he fac ha i is generaed by coal- fired saions. ) A cenury ago facories were dispersed ou of he ciies bu nowadays hey are in cenral urban areas. Passage : The High Elecron Mobiliy Transisor or HEMT is a form of filed effec ransisor (FET) ha is used o provide very high levels of performance a microwave frequencies. I offers a combinaion of low noise figure combined wih he abiliy o operae a microwave frequencies. The key elemen wihin a HEMT is he pn juncion ha i uses. I is Known as heero-juncion and consiss of a juncion ha uses differen maerials on eiher side. The mos common maerials used are aluminum gallium arsenide (ALGaAs) and gallium arsenide (GaAs). Gallium arsenide is generally used because i provides a high level of elecron mobiliy which is crucial o he operaion of he device. On he oher hand Silicon has a much lower level of elecron mobiliy and ha is why i is never used in a HEMT. There are a variey of differen srucures ha can be used wihin a HEMT. However, hey all basically use he same manufacuring processes.

2 مدرسان شريف رتبه يك كارشناسي ارشد - A HEMT ransisor offers. ) low noise ) high power ) operaing a microwave fequency ) & - Gallium arsenide is generally used in a HEMT ransisor since. ) i can no form a pn juncion ) i has a high level of elecron mobiliy ) i has a low level of elecron mobiliy ) Si has a level of elecron mobiliy Passage : For faul finding you mus have a leas a mulimeer eiher analogue or digial. An oscilloscope is no absoluely essenial bu you will find yourself very resriced wihou one. I s like rying o repair a car while wearing a blindfold. For audio equipmen, a signal source is needed. Clearly a funcion generaor is useful bu simpler and cheaper alernaives work well in mos cases. You only need a fixed frequency source, say 00 or 000 Hz sine or square wave. For cassee recorders a ape wih a consan 00 Hz wave recorded on boh channels is adequae for mos faul finding. However, for checking playback levels and frequency response and aligning he ape head, proper es apes, which are expensive, are required. For serious work, a collecion of es leads and audio connecors is essenial. Mos modern audio equipmens use Phono sockes so i s worhwhile invesing in cables which erminae in phono pugs. For oher ypes of sockes, adapors are available. 5- Wha is a less complicaed and less expensive alernaive for a funcion generaor? ) Signal source. ) A fixed source. ) Audio equipmens. ) Faul finding es apes. 6- Wha are phono sockes associaed wih? ) Adapors ) Tess leading o audio connecors. ) Cables which lead o phono plugs ) All of he above. Passage : Indusrial auomaion spans a huge specrum of complexiy in erms of boh he physical srucures of machines and he asks ha hey perform. This has led o an equally wide range of conrol sysem hardware and sofware building blocks. The general lack of sandardizaion beween differen conrol sysem componens makes indusrial conrol sysems difficul o mainain, modify and inegrae. This has encouraged users o go o a single vendor for all heir machine conrol needs in order o minimize such problems. The dominance of closed, vendor specific soluions generally resuled sagnaion raher han innovaion and improvemen in conrol sysems. 7- Which of he following does he auhor NOT lis as a characerisic of indusrial auomaion ha would resul in difficulies in conrol sysems? ) Novely. ) Complicacy. ) Lack of uniformiy in pars. ) Difficuly in making changes. 8- There is informaion in he passage o suppor which of he following conclusions? ) The vendor dependency has slowed down enhancemen in conrol sysems qualiy ) The adopion of beer design approaches is severely handicapped due o lack of knowledge ) The componens are usually seleced on a performance basis raher han vendor dependency. ) The machines consising of suiable combinaions of sysems hardware and sofware are easier o improve.

3 مدرسان شريف رتبه يك كارشناسي ارشد Passage 5: The MASSPOWE projec and is developmen represens a fuure model for how power generaion projecs may be pu ogeher in he new compeiive energy arena in he Unied Saes and in many counries hroughou he world. Gone are he days when elecric uiliies buil large cenral generaion saions on a cos-of-service basis as he only alernaive o providing elecric power and gone also are he early days of cogeneraion when hinly capialized enrepreneurs obained power conracs while working ou of heir suicases. The adven of formal compeiive bidding programs as he way of supplying new elecric power has expedied he mauring of he non uiliy power generaion indusry. The survivors of he ineviable consolidaion we are currenly winessing, will need o ake considerable marke and financial risk before reasonable assurance can be obained abou a projec s success. MASSPOWE was one of he firs projecs o be developed in his new climae and o have such a significan amoun of developmen capial pu a risk. Undersanding is developmen process can help o undersand wha i will ake o be successful a profiably building power plans in he fuure. 9- The auhor believes ha hose ineresed in he Masspower projec. ) have acceped is financial risk ) do no fully undersand is difficulies ) are hinking of finding way o ensure is success before building power plans ) have acceped ha power generaion based on cos of service is a good alernaive o Masspower generaion. 0- The passage provides informaion ha would answer all of he following quesions EXCEPT ) wha is considered on inviing program? ) wha does he auhor hink of large cenral power saions? ) does Masspower projec presen a posiive compeiive energy aciviy? ) does he auhor sugges he Masspower projec as he only alernaive o providing elecric power? - We may conclude from he passage ha ) he projec iniially conceived should be cenered around imporan facors ) masspower projec will be of lile success unless profiable power plans are developed ) if all he deails of he developmen process are digesed, he Masspower projec can be a success ) he enrepreneurs should have he required knowledge and skills o plan improved sraegies Passage 6: The beauy of hree-dimensional graphics packages used by engineers and scieniss is ha viewer can no only see an image in deph from differen angles bu can also manipulae i wih sofware.the resoluion of he image, however, is limied o he resoluion of he graphic program, or of he screen on which he graphics are viewed, which is ypically megapixels a mos. Holograms, on he oher hand, can conain erapixels of daa and are inherenly -D. Bu because hese holographic images are fixed in he holographic film, he viewer canno manipulae he image or inerac wih i, excep o view i from differen angles. Bu now, a research group a he Bauhaus Universiy in Weimar, Germany, has developed a mehod for combining he ineraciviy of compuer graphics wih he daa richness of he hologram by superimposing he holographic image and he -D graphics image. To undersand how he Bauhaus Universiy's mehod works, consider how a hologram is made and how i re-creaes a -D image of an objec. To make a hologram, laser ligh is spli ino wo ligh waves ha are iniially in phase. One of waves illuminaes he objec o be imaged, and he ligh refleced from he objec ravels o a holographic film. The second ligh wave, he reference wave, falls direcly ono he film. Because he disance ha he firs ligh wave ravels varies according o where i srikes he objecs, i will generally arrive a he film ou of phase wih he reference wave. The amoun by which i is ou of phase depends precisely on where i srikes he objec.

4 مدرسان شريف رتبه يك كارشناسي ارشد The wo ou of phase ligh waves creae an inerference paern on he film. And his inerference paern conains all of he informaion needed o re-creae a high-resoluion image of he objec when a hird ligh wave srikes he hologram a he same angle as he reference wave ha helped o creae i. In mos holograms, whie ligh, ypically from a halogen bulb, raher han laser ligh, is used o re-creae he image. To creae he superposiion of he wo images, Bauhaus Universiy researchers mainly use hree pieces of equipmen: an auosereoscopic display, which allows viewing of -D graphics wihou he use of special glasses: a whie ligh hologram; and a digial projecor, such one used o display presenaions sored on a compuer ono a large screen. The auosereoscopic display shows images of -D graphics hrough a plasic shee of iny lenses ha direc a differen image o each eye. The holographic film is direcly aached o he fron of he display screen. When he digial projecor illuminaes he hologram, he recreaed -D images from he hologram and he display appear o he viewer in he same volume of space. The power of he echnique comes from he abiliy o conrol he direcion and inensiy of he ligh from he digial projecor, and hus o conrol which pars of he hologram are re-creaed and which are no. - Wha is he difference beween a -D image and a holographic image? ) The former image is limied o he graphics program while he laer is ineracive. ) A -D image is limied in resoluion while a holographic image can conain erapixels of daa. ) In he forma he image has deph and can be manipulaed wih he help of a sofware while in he laer he image is fixed ) All of he above - Wha has research group a Bauhaus Universiy achieved? A Mehod. ) o recreae a -D image of an objec ) o manipulae he holographic image ) for combining he ineraciviy of compuer graphics ) o superimpose he holographic image and he -D graphics image. - Wha is mean by he reference wave? ) Laser ligh ) The ligh wave ha falls direcly ono he film. ) The hird ligh wave ha srikes he hologram. ) The ligh wave ha illuminaes he objec o be imaged. 5- Wha are he principal ools used o creae he image discussed in he passage? ) An auosereoscopic display, iny lenses, and a digial projecor. ) An auosereoscopic display, a large screen, and digial projecor. ) An aouosereoscopic display iny lenses. ) An auosereoscopic display, a whie-ligh hologram, and a digial projecor. Passage 7: Mos curren commercial packages for harmonic analysis use a direc soluion mehod whereby a harmonic curren source, specified in advance, i injeced ino he linear nework o deermine he volage and curren disorion levels. This approach provides realisic frequency domain models of he linear ac sysem. However, a harmonic curren source is usually an oversimplified model of he non-linear plan. The overall soluion for welve pulse converer es sysem depends no only on he sysem volage source, curren source and impedances, bu on converer variables such as conroller characerisics, firing angle consrains, ec. Ieraive echniques are hus necessary o solve all hese variables ogeher o reach a final correc soluion. In he harmonic models of ac-dc sysem available in he lieraure, he emphasis is on he soluion echnique, wih a clear rend owards he Newon mehod. In comparison, he quesion of model accuracy has been given very lile aenion and early models are sill superior o hose recenly described.

5 مدرسان شريف رتبه يك كارشناسي ارشد 5 Under realisic condiions, he swiching insan of he bridge valves are no equispaced over one cycle due o converer acion. The incorporaion of swiching angle modulaion in he converer model permis an accurae derivaion of he individual swiching insans; heir effec on ransfers beween he ac and dc sysem mus be quanified, and all causes influencing he modulaion mus be accouned for. An early cause of firing angle modulaion was he use of individual firing conrol. 6- Which mehod is used in commercial packages for harmonic analysis? ) Ieraive soluion ) Direcion soluion ) Indirec soluion ) Injecion soluion 7- For wha kind of sysem does he direc soluion mehod provide realisic frequency domain models? ) Linear ac sysems. ) Linear dc sysems. ) Non-Linear sysems. ) Linear ac and dc sysems. 8- Which of he following iems does he overall soluion for welve-pulse converer es sysem depends on? ) Converer variables ) Sysem volage sources ) Curren sources and impedances ) All of he above 9- Which echniques are imporan o solve for variables such as conroller characerisics and firing angle consrains? ) Direc soluion. ) Newon s mehod ) Indirec soluion. ) Ieraive echniques 0- Wha was an early cause of firing angle modulaion? ) The use of frequency conrol. ) The use of individual firing conrol. ) The use of impedance variable conrol. ) The use of harmonic curren source conrol. Passage 8: Facors associaed wih he scaling of CMOS echnology such as reliabiliy and densiy are driving down supply volages. Furhermore, he rapid growh of porable applicaions promoes baery operaion which favors low volage and low power circuis. As a resul, many sugges ha fuure implemenaion mixed analog-digial circuis using sandard CMOS will have power supplies of.5 V or less. Communicaion large-scale inegraions (LSI s) are prediced o be he arge. Threshold volages of fuure sandard CMOS echnologies may decrease much below wha is available oday. This poses a grea challenge o CMOS analog/mixed-signal circui design. Consider he sandard push-pull CMOS amplifier/inverer and ransmission gaes. These circuis require he analog power supply o be a leas equal o he sum of he magniudes of he n-channel and P-channel hresholds. Probably he mos imporan o he hreshold volage limiaion is he bulk-driven MOSFET. The gae-source poenial is aken o a dc volage ha is sufficien o urn on he MOSFET. The drain is conneced normally and he signal is applied. Beween he bulk and he source The curren flowing from he source o drain is modulaed by he reverse bias on bulk-channel juncion. The resul is a juncion field-effec ransisor wih he bulk as he signal inpu gae. Consequenly, a high-inpu impedance depleion-mode devicer resuls. - Wha facors are he driving forces reduced supply volages of CMOS? ) Device densiy. ) Device reliabiliy. ) Hybrid echnology. ) Boh and - Wha can be prediced as he grea challenge in designing he analog circuis? ) Low power CMOS. ) Threshould volage. ) Mixure of analog and digial blocks. ) Porable insrumens and baery using capabiliy.

6 مدرسان شريف رتبه يك كارشناسي ارشد 6 - The hreshold volage of sandard CMOS echnologies. ) need no change a all ) would be reduced drasically ) will have o decrease o mee he curren challenge ) may no decrease much below wha is available oday. - Wha is he mos viable soluion for he hreshold volage limiaions? ) Using BJT or JFET. ) Furher consumpion of nmos in oupu. ) Applying signal o bulk insead of he gae. ) Applying signal o he source insead of gae. 5- Taking he gae-source poenial o a dc volage sufficien o urn on he MOSFET, connecing drain normally and applying he signal beween he bulk and he source would resul in. ) low-inpu impedance depleion-mode device ) high-inpu impedance depleion-mode device ) low-inpu impedance enhancemen-mode device ) high-inpu impedance enhancemen-mode device cx y x dy dy dy dy x 6 y e dx dx dx dx yx x x x x (ccx) e e x x (ccx cx cx )e رياضيات 6 جواب معادله ديفرانسيل معمولي xy dx (x ) dy كدام است ( c y ( x yx c 7 جواب معادله ديفرانسيل زير كدام گزينه است با چه شرط (يا شرايطي) جواب مسي له كراندار ميماند v x e( ) v x x x x (ccx) e e 6 x x (ccx cx cx )e dx dx x d d 8 مسي له مقدار اوليه زير مفروض است x( ) x, x ( ) v v x( y () y() y(x) dx, y( ) و آنگاه y() برابر است با: e( ) e ( ) ( v x y( ) 9 اگر e ( ) y( ) dx dy xy 5sin d d dx dy xy e d d 0 در دستگاه معادلات ديفرانسيل با شرايط )x ( و كدام عبارت y() را بيان ميكند e 5sine ( e 5sine 5sin 5cos e e 5sin 5cos e e

7 مدرسان شريف رتبه يك كارشناسي ارشد 7 ygx f(x)e g(y) cogx سري فوريه كسينوسي نيمدامنه تابع f را بنويسيد هرگاه در ناحيهاي كه f غيرصفر است تعريف آن به صورت: m ( ) ( m ) x f(x)~ cos m (m ) m ( ) ( m ) x f(x)~ cos m (m ) 6 6 ygx ce y co gx (,x باشد كه در آن. H(x),x f(x) H( x) H( x) H( x) m ( ) ( m ) x f(x)~ cos m (m ) m ( ) ( m ) x f(x)~ cos m (m ) sinnx f(x)sin xdx باشد حاصل f(x) هرگاه n كدام گزينه است 8 ( n ) صفر پاسخ كامل معادله ديفرانسيل du co gx u y كداميك از گزينههاي زير است dy ygx g(y)e y co gx ( ygx f(x)e ycogx u u u x) y) (x را در نظر ميگيريم. اين معادله در نيمصفحهي بالاي معادله ديفرانسيل با مشتقات جزي ي x xy y محور y) )x از كدام نوع است ) سهميگون ) در بخشي بيضيگون و در بخشي هذلوليگون ) بيضيگون ) هذلوليگون u u 5 در يك ناحية نيمه محدود ( x) معادلة حرارت را به صورت x و در نظر ميگيريم. حالت اوليه عبارت است c x ( u(x, و ناحيه در x عايق شده است. پاسخ عمومي معادله u(x,) به كدام صورت است از f(x) pc D(p)e cos pxdp ( pc D(p)e sin pxdp y b V(0,y) = V0 0 r sin pc e [A(p)cospx B(p)sinpx]dp V (x,b) = 0 y V(x,0) = 0 ( e) i pc e [A(p)cospx B(p)sinpx]dp 6 اگر بخواهيم توزيع پتانسيل را در داخل شكل زير به دست آوريم كداميك از جوابهاي زير ميتواند مناسب باشد x An coshknxsinkny An cosh knx cos kny (An coshknx Bn sinknx)coskny (An cosh knx Bn sinh knx)sin kny ( f(z) اگر 7 يك تابع تحليلي با قسمت حقيقي u(x,y) x e cosy باشد ()f برابر است با: e i e ( I براي يكبار طي كردن كامل (در جهت مثبت) مسير بستة C كه در مختصات قطبي به صورت i a V(a,y) = 0 z z! i ( C e dz 8 حاصل انتگرال z ميباشد برابر است با: i 9 دو جملهي اول غير صفر بسط ماكلورن تابع (z f(z) sin(sin در صفحة مختلط عبارت است از: z z z z! ( z z

8 مدرسان شريف رتبه يك كارشناسي ارشد 8 تابع f(z) e z را در نظر ميگيريم. وقتي z روي خط y x در ربع اول و با x هاي كاهشي به سمت نقطهi z ميل كند مقداري كه 0 f(z) به خود ميگيرد برابر است با: ) بينهايت + ( ) صفر اگر با فرضy متغير z به سمت بينهايت ميل كند در اين صورت در مورد كراندار بودن و يا داراي حد بودن sinz كدام عبارت درست است ) كراندار است و به صفر ميل ميكند. ) به بينهايت ميل ميكند. XY m ) كراندار است اما به سمت حدي ميل نميكند. ) كراندار است اما به صفر ميل نميكند. اگر X و Y متغيرهاي تصادفي دو جملهاي مستقل با پارامترهاي يكسان n و P باشند تابع چگالي احتمال شرطي X به شرط k m 7 يعني m) P(X k, X Y برابر كدام است n n n n k m k m k k ( n n n m m m فرض كنيد تابع چگالي احتمال توأم متغيرهاي تصادفي X و X به صورت زير باشد: X x x, x, x. f X,X (x,x ) در اين صورت ) P( برابر است با: X ساير جاها, 5 9 ( اگر X و Y دو متغير تصادفي مستقل و با توزيع يكسان (iid) باشند آنگاه (Y P(X برابر است با: ( ) بستگي به توزيع X و Y دارد. 5 فرض ميكنيم تعداد اتومبيلهاي عبوري از مقابل يك دوربين عكاسي در بازه زماني T يك متغير تصادفي پواسون با چگالي باشد اگر دوربين عكاسي مستقلا با احتمال P از هر اتومبيل عكس بگيرد ميانگين تعداد عكسهاي گرفته شده در بازه زماني T برابر است با: P T PT PT( P P=6w P=-w I مدارهاي الكتريكي 6 در مدار مقاومتي شكل زير توان هر يك از عناصر داده شده است. جريان I چقدر است A A ( P =w P=w v A 6 A 7 در مدار شكل مقابل فرض كنيد تمام مقاومتها سه برابر شوند و مقدار ثابت نگه داشته شود. مقدار g m چگونه تغيير كند تا مقادير ولتاژ 5 شاخهها تغيير نكند g m تغيير نكند. e s + V x - BI y gmvx 6 I y m g در ضرب شود. ( g m در ضرب شود. ) نميتوان بدون داشتن مقادير مقاومتهاي مدار اظهار نظر قاطع كرد.

9 مدرسان شريف رتبه يك كارشناسي ارشد 9 I 8 مقاومت معادل بين دو سر A و B مدار داده شده در شكل مقابل كدام است / I 9 I 7 A B / 5( / / V o ولتاژ خروجي 9 در مدار شكل مقابل كدام است 0. 0 v + v - I V I + vo - ( مشخصه يك قطبي N در مدار شكل زير داده شده است جريان i در اين مدار برابر است با: N + vn - IN I I 5v 5 9 A 9 A ( 5 0.5I A 0. IN(A) 9 A 9 5 مدار شكل زير در در حالت صفر فرض ميشود جريان () I گذرنده از خازن در اين مدار عبارتست از: C vn(v).8 e C u() V() S I C C C e C e u() u() ( u() ) بدون داشتن ورودي V() S اين جريان قابل محاسبه نيست. در S در مدار شكل مقابل كليد 5 بسته ميشود و مدار در حالت ميراي ي بحراني قرار ميگيرد جريان () I كدام است L 5 ( / / 5)e u() u( ) F I L 50 S H ( / / 5)e u() ( / 5)e u() 5 ( / 5)e u() (

10 مدرسان شريف رتبه يك كارشناسي ارشد 0 V() ميچرخانيم. ولتاژ ac كليد را به وضعيت قرار داشت. در لحظه ab براي مدت طولاني در وضعيت S در مدار شكل زير كليد 5 براي برابر است با: 5v A 5 F + - V b a c () e e ( e 5 5 e 5 5 u() a L ab b L M L H di L 5 در مدار شكل زير ) )V o و ) ( چقدر است (جريان اوليه سلف و ولتاژ اوليه خازن را صفر فرض كنيد.) d 0V o F + : M = H H I L H V o - A 8 sec, v A 9 sec, v ( A 8 sec, v A 9 sec, v 55 در مدار شكل مقابل سلف معادل ديده شده از دو سر a و L) ab ) b چند هانري است 9 ( در مدار شكل زير جريان حالت داي م عبوري از بار Z برابر با صفر است. مقدار ضريب اندوكتانس متقابل M چقدر است V S Z C C L L ( LL C LC L 57 در مدار شكل مقابل به ازاء چه مقدار برحسب اهم توان متوسط دريافتي آن حداكثر ميشود H ( cos H F 9