Presentation on theme: "What Electrical & Computer Engineering Can Do for You?"— Presentation transcript:
1 What Electrical & Computer Engineering Can Do for You? Science & Engineering Saturday Seminar23 January, 2010Marinos N. VouvakisSpecial Thanks to: Baird Soules, Kris Hollot, Maciej Ciesielski, Wayne Burleson, Pat Kelly, Sandip Kundu, Russ Tessier
2 Who Am I? Professional: Assistant Professor in ECE (5 years at UMass) Teaching: Electromagnetics, Mathematics, AntennasResearch: Computational Electromagnetics & AntennasEducation:PhD 2005, The Ohio State UniversityMS 2002, Arizona State UniversityDipl. Ing 1999, Democritus University of Thrace, GreecePersonal:Hellenic National, Crete33 years old (single)Favorite Music: Velvet Underground, Slint, FugaziFavorite Sport: BasketballHobbies: Traditional Greek music, politics, history, play with my cats.
3 Seminar Objectives Why am I doing this? Science vs. Engineering? What is Electrical & Computer Engineering?What are major ECE sub-areas?What are the trends?A Closer look at some basic concepts ECE:Analog CKTs (sensing & signals)Digital (entering the Digital world)Wireless (the communications revolution)DemosSensing & Transducers (Chris)Sampling & Bits (Baird, Marinos)
4 Why am I participation on this Seminar Series? The VisionI want to make impact on society.Engineering is key to a better future for humans and our environment.The ProblemLow engineering enrolments nationwide.Alarming enrolment trends.Most teachers do not have engineering background.A Possible solutionWhen incoming students are aware about engineering is, they are likely to choose it.Educate teachers about engineering.
6 Science vs. Engineering Science: Why things happen the way they happen?Example: Movement of objects (force, friction, etc)Engineering: Creative problem solving.More formally: engineering is the discipline, art and profession of acquiring and applying knowledge to design and implement materials, structures, machines, devices, systems, and processes that realize a desired objective.Example: Wheel!!Engineering = applied science
7 Science vs. Engineering (cont’d) The Taxonomy of LearningCreateEngineeringEvaluateAnalyzeApplyUnderstandRememberQ: Can we have engineering without science (or vise-versa)?
8 Science and Engineering ObservationScienceFirst PrinciplesInstrumentationMathematicsEngineeringIntuition
9 Science and Engineering (cont’d) Beliefs/behaviorsTechnologySocietyEngineeringTechnology logic = (art/craft)+(knowledge/logic)
10 Engineering Grand Challenges* Make solar energy economical Provide energy from fusionProvide access to clean waterReverse-engineer the brainAdvance personalized learningDevelop carbon sequestration methodsEngineer the tools of scientific discoveryRestore and improve urban infrastructureAdvance health informatics Prevent nuclear terrorEngineer better medicinesEnhance virtual realityManage the nitrogen cycleSecure cyberspace*Source: US. National Academy of Engineering
16 Electrical and Computer Engineering “Electrical engineering is an engineering discipline that deals with the study and/or application of electricity, electronics and electro-magnetism.”“Computer engineering is a discipline that combines elements of both electrical engineering and computer science. Computer engineers are involved in many aspects of computing, from the design of individual microprocessors, personal computers, and supercomputers, to circuit design.”Easier to understand by exploring example systems
24 Future ECE Job Prospects* Computer hardware engineers are expected to have employment growth of 4 percent over the projections decade, for all occupations. Although the use of information technology continues to expand rapidly, the manufacture of computer hardware is expected to be adversely affected by intense foreign competition. As computer and semiconductor manufacturers contract out more of their engineering needs to both domestic and foreign design firms, much of the growth in employment of hardware engineers is expected to take place in the computer systems design and related services industry.Electrical engineers are expected to have employment growth of 2 percent over the projections decade. Although strong demand for electrical devices including electric power generators, wireless phone transmitters, high-density batteries, and navigation systems should spur job growth, international competition and the use of engineering services performed in other countries will limit employment growth. Electrical engineers working in firms providing engineering expertise and design services to manufacturers should have better job prospects.Electronics engineers, are expected to experience little to no employment change over the projections decade. Although rising demand for electronic goods including communications equipment, defense-related equipment, medical electronics, and consumer products should continue to increase demand for electronics engineers, foreign competition in electronic products development and the use of engineering services performed in other countries will limit employment growth. Growth is expected to be fastest in service-providing industries particularly in firms that provide engineering and design services.*Bureau of Labor & Statistics
25 Electrical & Computer Engineering Systems An advanced “engineering” systemReact
27 Charge & Electric Current Each electron carries an electrical charge, q of –1.602x10-19 coulombs [C]1 [C] = the charge of 6.242x1018 electronsCurrent, I or iflow rate of electrical charge through a conductor or a circuit elementUnit: ampere [A]. 1A=1C/sCurrent-charge relationship:
28 Direct Current (DC) & Alternating Current (AC) Current that is constant with timeFor examples, I=3A or V=12VACCurrent that varies with time and reverses its direction periodically (sinusoidal)For example,Thomas Edison(1847 – 1931)Nikola Tesla(1856 – 1943)
29 Water-Model Analogy We cannot see electric current flowing in a wire Water-model or fluid-flow analogy helps us visualize the behaviors of electrical circuits and elementsElectric Current = flow of electrical charges(Water) Current = flow of water moleculesAssumptionsFrictionless pipesNo gravity effectIncompressible wateri(t)wire / pipecross section
30 Material Types Conductors Insulators Semiconductors Superconductors Electric currents flow easily.Examples: copper, gold, aluminum…InsulatorsDo not conduct electricity.Examples: ceramics, plastic, glass, air…SemiconductorsSometimes conductors, sometimes insulatorsExamples: silicon, germaniumApplications: transistorsSuperconductorsPerfect conductors when cooledApplications: MRI, astronomy
31 Voltage Voltage Water models Measured between two points (terminals) Energy transferred per unit of charge that flows from one terminal to the otherIntuitive interpretations: potential difference, water pressure in water modelVariable:Unit: volt [V]Water modelsFor constant voltage sourcesConstant-pressure water pumpConstant-torque motorAlessandro Volta(1745 – 1827)
32 Rules of Current Flow - Kirchhoff’s Current Law Kirchhoff’s current law (KCL)Conservation of electrical currentsThe sum of all the currents into a node is zeroThe sum of the currents entering a node equals the sum of the currents leaving a nodeGustav Kirchhoff(1824 – 1887)node
33 Rules of Current Flow - Kirchhoff’s Voltage Law Kirchhoff’s voltage law (KVL)Conservation of energyThe sum of the voltages around any closed path (loop) is zeroExampleloop 31539+_124loop 1loop 2
34 CKT Components - The Resistor Electrical component that resists the current flowVariable: R [ohm] orWater models for a resistorRconstrictionRRsponge=~
35 Incandescent Light Bulb Resistors in PracticeResistive Touch-screenPower Supplies
36 Rules of Current Flow - Ohm’s Law Power dissipated in a resistorGeorg Ohm(1789 – 1854)Rv(t)_+i(t)
39 CKT Components - The Capacitor Capacitor & CapacitanceStores energy through storing chargeConstruction: separating two sheets of conductor by a thin layer of insulatorVariable: CUnit: Farad [F]. 1F=1 coulomb per voltMichael Faraday( )capacitorC
43 CKT Components - The Inductor Stores energy through storing magnetic fieldConstruction: coiling a wire around some type of formVariable: L [Henry] or [H].When the electric current changes in the coil, it creates a magnetic field around the wire which induces voltage across the coil+_LJoseph Henry( )
44 CKT Components - The Inductor (cont’d) OperationWhen the electric current changes in the coil, it creates a magnetic field around the wire which induces voltage across the coilWater model analogyBi-directional turbine driving a flywheelPassive, driven by current; no motorMomentum
45 Inductor Equations Current: + Voltage: L Energy Stored: _ MATH (differentiation) = CKT (inductor) !!!
47 CKT Components - The Transistor Transistor is active component (generates energy)Controls the flow of currentsConstruction: combine semiconductor materials (many different implementations)The key element in any ECE applicationC (collector)John BareenWalter BrattainWilliam Shockley(1947)B (base)E (emitter)*Julius Edgar Lilienfield (1925)!!
48 Transistor OperationUse base voltage to control current flow on collectorAmplification (analog CKTs)Switching (digital CKTs)C (collector)1B (base)amplifierswitchE (emitter)
49 Circuit Schematics connection no connection wires R + + V _ V I resistorbatteryvoltagesourcecurrentsourceLCterminalsinductorgroundcapacitortransistor
50 An Analog CKT System High-End Sound Amplifier CKT design Hardware Implementation
53 The Digital WorldBiological Systems:Electrical Systems:
54 Binary in History Yin-Yang Emblem G. Leibniz Pa Kua: Eight Trigrams ( )Pa Kua: Eight TrigramsBinary exists for thousand of years in ancient Chinese history: yin-yang trigrams hexagramsG. Leibniz, 1679: formal development of the system of binary arithmetic
58 Entering and Exiting the Digital World… (cont’d)
59 Sampling ^ x(t) t x(t) t t x(t) ^ t x(t) Increases the sampling rate and the amplitude resolution by a factor of 2tx(t)^tx(t)
60 Sampling (cont’d) 300Hz 700Hz Sampling rate: 1000Hz Sampling rate: How fast should we sample?Fewer samples are needed for a slowly-changing signal. More samples are required for fast-changing signalsWhat is the critical sampling rate?Consider the sampling of a simple sinusoid700Hz300HzSampling rate: 1000Hz
61 Sampling (cont’d) Aliasing 700Hz Sampling rate increases to: 1400Hz Ambiguity in the reconstruction: 700Hz sinusoid can be mistakenly identified as a 300Hz sinusoid in exampleGenerally, aliasing error results from not having enough samples for fast-changing signalsTo avoid aliasing, sample fast enough!700HzSampling rate increases to: 1400Hz
63 Example: Digital Audio processing or storage of digital signal (e.g., MP3)
64 Analog to Digital Recording Chain ADCMicrophone converts acoustic waves to electrical energy. It’s a transducer.Analog signal: continuously varying electrical energy of the sound pressure wave.ADC (Analog to Digital Converter) converts analog to digital electrical signal.Digital signal: digital representation of signal in binary numbers.DAC (Digital to Analog Converter) converts digital signal in computer to analog for your headphones.
65 Measure amplitude at each tick of sample clock Digital Quantization3-bit quantization: use 3 bits to represent values 0,1,…71234567AmplitudeMeasure amplitude at each tick of sample clockTime
66 Decimal-Binary Conversion QuotientRemainderDivide the decimal number repeatedly until the quotient is zero. The remainders in reverse order give the number’s equivalent binary form343/21711171/28585/24242/22121/21010/255/222/21/2=1021 x x x x x 2+ 0 x x x x 2 = 34387654321
67 The Digital Audio Stream A series of sample numbers, to be interpreted as instantaneous amplitudesone number for every tick of the sample clockFrom previous example:This is what appears in a sound file, along with a header that indicates the sampling rate, bit depth and other thingsEach number is then converted to binary and stored in a register
69 Digital Technology: DVD Digital Versatile Disc or Digital Video DiscFirst appeared in the US market in March 1997Employ the same red laser as in CDsHigher-density multi-layer discs to improve storage capacityDVD Audio: 192-kHz 24-bit sampling rate!
70 Digital Technology: DVD SpecificationCDDVDTrack Pitch1600 nm740 nmMin. Pit Length830 nm400/440 nmStorage Capacity780 MBGB
73 Binary Arithmetic - Addition (cont’d) Truth Table of Half-AdderInputsOutputsABSumCarry1ABSumCarryXORANDWhat about n-bit inputs?
74 Principle of Binary Addition Very similar to decimal additionStarting from least significant bit (LSB), keep track of partial sum & carry until reaching most significant bit (MSB)Simpler than decimal addition: only 0 and 1 are involvedExample11111carry11carry108++MSBLSB931111201Binary AdditionDecimal Addition
75 Binary Arithmetic - Addition the Full Adder InputsOutputs1We need to add three bits (A, B, and Carry), not two as in the half-adderThis is called a full adderCarry-outCarry-inFASum
76 Binary Arithmetic - the N-bit Full Adder S7CoS8A6B6S6A5B5S5A4B4S4A3B3S3A2B2S2A1B1S1CiA0B0S0first carry in,set to 0 herelast carry out,overflow bit8-bit Full AdderCKT = MATH (= $$$$$)
84 SoftwareSoftwareContains instructions for the computer to accomplish certain tasksFlexible, easy to modify, copy, and transportData manipulationsArithmetic operations: additions, multiplications, logarithms, trigonometric functions…Logic operations: from OR, AND, NOT to complex logic functions…Conditional operations: if then else…For ECE research and developmentMatlab, Mathematica, Maple, Mathcad, Labview, Cadence, develop our own software using programming languages such as C++, Java, FORTRAN…
85 Software Building Block Hierarchy Assembly codeMost basic low-level programming codesDifferent and need to be optimize per processor typeOperating System (OS)Set of basic instructions for I/O, file system, resource sharing, security, graphical user interface (GUI)UNIX/Linux, Windows, MS-DOS, MacOS…High-level programming languageProvide more general, more powerful, more abstract instructions for the computerVisual BASIC, FORTRAN, C, C++, Java…ApplicationUser-friendly software package for popular applicationsWord processors, & web browser, games…MOV 520 R0ADD R0 R1UNIX: ls –lrm *.*DOS: dirdel *.*C++: x++Fortran: x=x+1WordExplorerSims
87 Cell PhoneA cell phone is a very complex system that can receive input signals in various forms (electromagnetic waves from base station, sound from microphone, text from key pad) and convert them to several desired types of output signals (sound through speaker, electromagnetic waves to base station, graphics to screen)
88 Cell Phones: Inside front back LCD & keypad microprocessor flash memoryspeaker, microphone
90 Sound Fundamentals Sound waves: vibrations of air particles Fluctuations in air pressure are picked up by the eardrumsVibrations from the eardrums are then interpreted by the brain as sounds
91 Harmonics in Music Signals The spectrum of a single note from a musical instrument usually has a set of peaks at harmonic ratiosIf the fundamental frequency is f, there are peaks at f, and also at (about) 2f, 3f, 4f…Best basis functions to capture speech & music: cosines & sines
92 Frequency How fast a vibration happens High frequency -> fast vibration (voice/music: soprano)Low frequency -> slow vibration (voice/music: baritone)The frequency f is the inverse of the period TSinusoidal frequencyUnitsPeriod: second (unit of time)Frequency: 1/sec or hertz [Hz]Phase: radians
98 Modulation (cont’d) Modulation Pulse modulation Amplitude modulation Using higher-frequency sinusoids to carry signalsMore efficient transmission & allow multi-user sharingPulse modulationAmplitude modulationFrequency modulationMorse code,infrared remote control…AM radio stations,video part of TV signals…FM radio stations,Cell phones, cordless phones…
99 Radio Frequency Systems An advanced RF /microwave systemDSP/ProcessorA/DwaveguideT/RswitchPAMixerVCOAntennaLOLNAPowerSupply
100 Modem Transmission 1 1 Transmit Receive frequency 1 1 Frequency-shift keying (FSK)Uses analog sinusoids of different frequencies to carry digital signals11TransmitReceivefrequency3001070127020252225330011
102 The Cell ApproachCellular telephone system is based on the principle of radio communicationCoverage area is divided into hexagonal cells (each covers around 10 square miles)Non-adjacent cells can reuse the same frequenciesLow-power transmitters: both phones & base stationsEach city has a Mobile Telephone Switching Office (MTSO)Each carrier: 832 radio frequenciesDuplex system: 395 voice channels & 42 control channelsEach cell: 56 voice channels
103 From Cell to CellSystem Identification (SID) code to check for available serviceMTSO uses the control channels to identify where the user is & assign frequenciesMTSO handles the hand-off switching between cells based on signal strengthsEverything happens within seconds or even less!
104 Switching, RF and Power Electronics Cell Phone TowerAntenna ArraySwitching, RF and Power Electronics
105 What Next? Connect & collaborate with UMass Amherst ECE faculty Teacher development grantsSummer research experience for teachersRecommend exceptional high-school juniors/seniors summer research at UMass.Invite UMass Profs to High-school student seminars.M5 Open house for students and Teachers.Spread the word to students & colleagues.Participate on upcoming ECE SESS(more in-depth).Marinos N. Vouvakis
106 DisclaimerSome materials (drawings, figures, text) presented in these slides was obtained from the following web resources: