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Saturday 26 November 2011
Friday 18 November 2011
Electrical engineer interview questions
1. What types of CMOS memories have you designed? What were their size? Speed? Configuration Process technology?
2. What work have you done on full chip Clock and Power distribution? What process technology and budgets were used?
3. What types of I/O have you designed? What were their size? Speed? Configuration? Voltage requirements? Process technology? What package was used and how did you model the package/system? What parasitic effects were considered?
4. What types of high speed CMOS circuits have you designed?
5. What transistor level design tools are you proficient with? What types of designs were they used on?
6. What products have you designed which have entered high volume production?
7. What was your role in the silicon evaluation/product ramp? What tools did you use?
8. If not into production, how far did you follow the design and why did not you see it into production?
2. What work have you done on full chip Clock and Power distribution? What process technology and budgets were used?
3. What types of I/O have you designed? What were their size? Speed? Configuration? Voltage requirements? Process technology? What package was used and how did you model the package/system? What parasitic effects were considered?
4. What types of high speed CMOS circuits have you designed?
5. What transistor level design tools are you proficient with? What types of designs were they used on?
6. What products have you designed which have entered high volume production?
7. What was your role in the silicon evaluation/product ramp? What tools did you use?
8. If not into production, how far did you follow the design and why did not you see it into production?
Thursday 10 November 2011
Using Ideal Sources
The idea of using ideal sources is something that you may rebel at. After all, there is no such thing as an ideal source anywhere in the world. You can't pull an ideal source off the shelf in the lab, so why are we even talking about them? The answer to that question is that you use ideal sources when you have a non-ideal (a real source) source in a circuit. There are two important things to note.
* There are some sources that are very good sources and that can be modelled as ideal sources. (And when that happens, be grateful.) Some situations like that include the following.
o A power supply in the lab. Many times you connect a power supply to some electronic circuit, for example, and when you connect the circuit you find that the output voltage from the power supply doesn't change measurably. (After all, power supply designers try to make that happen!) In that case, the power supply might be considered to be an ideal source - at least as long as you are working on that particular circuit.
* There are many sources that do not perform ideally. However, it has proven to be possible to construct models of real sources, and those models often contain ideal source in combination with other ideal elements (like resistors, etc.). Thevinin and Norton equivalent circuits are examples of models of real sources that can account for loading effects (i.e. drawing enough current from the source to change the output voltage) and they are widely used in circuit analysis. You will even find that manufacturers give you parameter values for Thevinin and Norton equivalents on the front panel of many instruments like function generators.
You often have situations in which the sources that you use can be approximated with ideal sources. Shown below is a bridge circuit powered by a battery. Often a battery maintains a pretty constant voltage across the terminals, so you may be able to replace the battery with an ideal voltage source when you analyze the circuit.
Here's the circuit with an ideal voltage source substituted for the battery. At this point, you may know how to do the analysis so you're ready to go.
* There are some sources that are very good sources and that can be modelled as ideal sources. (And when that happens, be grateful.) Some situations like that include the following.
o A power supply in the lab. Many times you connect a power supply to some electronic circuit, for example, and when you connect the circuit you find that the output voltage from the power supply doesn't change measurably. (After all, power supply designers try to make that happen!) In that case, the power supply might be considered to be an ideal source - at least as long as you are working on that particular circuit.
* There are many sources that do not perform ideally. However, it has proven to be possible to construct models of real sources, and those models often contain ideal source in combination with other ideal elements (like resistors, etc.). Thevinin and Norton equivalent circuits are examples of models of real sources that can account for loading effects (i.e. drawing enough current from the source to change the output voltage) and they are widely used in circuit analysis. You will even find that manufacturers give you parameter values for Thevinin and Norton equivalents on the front panel of many instruments like function generators.
You often have situations in which the sources that you use can be approximated with ideal sources. Shown below is a bridge circuit powered by a battery. Often a battery maintains a pretty constant voltage across the terminals, so you may be able to replace the battery with an ideal voltage source when you analyze the circuit.
Here's the circuit with an ideal voltage source substituted for the battery. At this point, you may know how to do the analysis so you're ready to go.
What Is An Ideal Current Source?
An ideal current source is a simple model for many current sources. It is reminiscent of the ideal voltage source - but with voltage and current interchanged. Here is the story.
* There is a special circuit symbol for an ideal current source. See below
* IL = constant, no matter what the terminal voltage is.
* The plot of load current against terminal voltage is similar to the plot for an ideal voltage source, but voltage and current are interchanged. Here is the plot.
Notice that an ideal current source is somewhat similar to an ideal voltage source. However, when you use an ideal source - usually when doing circuit analysis- there is a significant difference in the analysis. However, that's getting ahead of the story. We first have to worry about how you would "use" an ideal source, when we know that there is no such thing as an ideal source, i.e. a source that is "perfect" in some way.
* There is a special circuit symbol for an ideal current source. See below
* IL = constant, no matter what the terminal voltage is.
* The plot of load current against terminal voltage is similar to the plot for an ideal voltage source, but voltage and current are interchanged. Here is the plot.
Notice that an ideal current source is somewhat similar to an ideal voltage source. However, when you use an ideal source - usually when doing circuit analysis- there is a significant difference in the analysis. However, that's getting ahead of the story. We first have to worry about how you would "use" an ideal source, when we know that there is no such thing as an ideal source, i.e. a source that is "perfect" in some way.
Ideal Voltage Source?
The concept of an ideal voltage source is pretty simple,
* An ideal voltage source is a voltage source that maintains the same voltage across the source's terminals no matter what current is drawn from the terminals of the source or what current flows into the terminals.
That's it in a nutshell. If the source is a DC Source, we can plot a voltage current plot for an ideal voltage source. The plot is shown below. However, we need to define terms. Here is a circuit symbol for an ideal voltage source. In this symbol, we assume the following.
* The voltage across the terminals is denoted as Vt.
* The load current flowing from the source to a load (presumably a load is attached when the source is in a circuit) is denoted as IL.
* With those definitions, here is the source symbol. It's just a circle with polarity indicated.
And, here is the plot of terminal voltage against load current.
Given the discussion above, we can say:
* Vt = constant, no matter what the load current is.
That's pretty much the description of the ideal voltage source. It's not too complex, but it is an important concept. In the next section we'll look at how you can put this concept to use. For the rest of this section we'll look at ideal current sources starting next.
* An ideal voltage source is a voltage source that maintains the same voltage across the source's terminals no matter what current is drawn from the terminals of the source or what current flows into the terminals.
That's it in a nutshell. If the source is a DC Source, we can plot a voltage current plot for an ideal voltage source. The plot is shown below. However, we need to define terms. Here is a circuit symbol for an ideal voltage source. In this symbol, we assume the following.
* The voltage across the terminals is denoted as Vt.
* The load current flowing from the source to a load (presumably a load is attached when the source is in a circuit) is denoted as IL.
* With those definitions, here is the source symbol. It's just a circle with polarity indicated.
Given the discussion above, we can say:
* Vt = constant, no matter what the load current is.
That's pretty much the description of the ideal voltage source. It's not too complex, but it is an important concept. In the next section we'll look at how you can put this concept to use. For the rest of this section we'll look at ideal current sources starting next.
What Is An Electrical Source?
You probably suspect an electrical source has to be something that gives you a voltage or a current, and you would be correct. In fact, there are two different kinds of ideal electrical sources - voltage sources and current sources.
Saturday 29 October 2011
Electric Power
Electric Power :
(electricity) The rate at which electric energy is converted to other forms of energy, equal to the product of the current and the voltage drop.
power, electric, energy dissipated in an electrical or electronic circuit or device per unit of time. The electrical energy supplied by a current to an appliance enables it to do work or provide some other form of energy such as light or heat. Electric power is usually measured in Watts,kilowatts (1,000 watts), and megawatts (1,000,000 watts). The amount of electrical energy used by an appliance is found by multiplying its consumed power by the length of time of operation. The units of electrical energy are usually watt-seconds (joules), watt-hours, or kilowatt-hours. For commercial purposes the kilowatt-hour is the unit of choice.
(electricity) The rate at which electric energy is converted to other forms of energy, equal to the product of the current and the voltage drop.
power, electric, energy dissipated in an electrical or electronic circuit or device per unit of time. The electrical energy supplied by a current to an appliance enables it to do work or provide some other form of energy such as light or heat. Electric power is usually measured in Watts,kilowatts (1,000 watts), and megawatts (1,000,000 watts). The amount of electrical energy used by an appliance is found by multiplying its consumed power by the length of time of operation. The units of electrical energy are usually watt-seconds (joules), watt-hours, or kilowatt-hours. For commercial purposes the kilowatt-hour is the unit of choice.
Mesh or Loop Analysis For Electric Circuits
Mesh Analysis :
This is also called Loop Analysis.This method uses simultaneous equations, Kirchhoff's Voltage Law, and Ohm's Law to determine unknown currents in a network.
Mesh Analysis only works for planar circuits :circuits that can be drawn on a plane (like on a paper) with out any elements or wires cossing each other. In some cases a circuit that looks nonplanar can be made in to a planar circuit by moving some of the connecting wires.
The first step in the mesh Current method is to identify "loops" with in the circuit encompassing all components. Represent all the loops with different loop currents in one direction.The choice of each loop current's direction is entirely arbitrary.
The next step is to label all voltage drop polarities across resistors according to the assumed directions of the mesh currents.
Next write the KVL equations for each mesh and solve all the equations for mesh (loop)currents.
Example :
KVL equation for Loop1 : -28 + 2(I1+I2) + 4*I1 =0.
KVL equation for Loop2 : -2(I1+I2) + 7 - 1I2=0.
Solving these 2 equations we get I1=5A I2=-1A.
The solution of -1 amp for I2 means that our initially assumed direction of current was incorrect. In actuality, I2 is flowing in a counter-clockwise direction at a value of (positive) 1 amp.
This is also called Loop Analysis.This method uses simultaneous equations, Kirchhoff's Voltage Law, and Ohm's Law to determine unknown currents in a network.
Mesh Analysis only works for planar circuits :circuits that can be drawn on a plane (like on a paper) with out any elements or wires cossing each other. In some cases a circuit that looks nonplanar can be made in to a planar circuit by moving some of the connecting wires.
The first step in the mesh Current method is to identify "loops" with in the circuit encompassing all components. Represent all the loops with different loop currents in one direction.The choice of each loop current's direction is entirely arbitrary.
The next step is to label all voltage drop polarities across resistors according to the assumed directions of the mesh currents.
Next write the KVL equations for each mesh and solve all the equations for mesh (loop)currents.
Example :
KVL equation for Loop1 : -28 + 2(I1+I2) + 4*I1 =0.
KVL equation for Loop2 : -2(I1+I2) + 7 - 1I2=0.
Solving these 2 equations we get I1=5A I2=-1A.
The solution of -1 amp for I2 means that our initially assumed direction of current was incorrect. In actuality, I2 is flowing in a counter-clockwise direction at a value of (positive) 1 amp.
Friday 28 October 2011
2011 QS World University Rankings by Subject - Engineering & Technology Rankings
Electrical Engineering Rankings 2011
Rank Title Country Academic Employer Citations Score
1 Massachusetts Institute of Technology (MIT) United States 100.0 84.9 56.8 82.5
2 Stanford University United States 91.3 73.9 69.7 79.6
3 University of Cambridge United Kingdom 83.0 93.8 43.1 74.3
4 University of California, Berkeley (UCB) United States 92.5 64.4 55.9 73.1
5 University of Oxford United Kingdom 66.0 94.1 61.3 73.0
6 Harvard University United States 65.9 100.0 52.1 72.0
7 California Institute of Technology (Caltech) United States 72.9 43.8 76.1 65.1
8 University of California, Los Angeles (UCLA) United States 64.2 63.7 63.4 63.8
9 Imperial College London United Kingdom 66.1 65.7 48.3 60.6
10 National University of Singapore (NUS) Singapore 63.2 57.4 44.7 55.9
11 ETH Zurich (Swiss Federal Institute of Technology) Switzerland 62.2 49.9 50.6 55.0
12 Princeton University United States 59.9 40.6 56.8 53.2
13 University of Toronto Canada 61.1 45.5 45.3 51.7
14 University of Pennsylvania United States 33.8 55.0 70.4 51.1
15 The University of Melbourne Australia 47.0 68.1 38.5 50.8
16 Carnegie Mellon University United States 57.6 41.4 46.4 49.4
17 The University of Tokyo Japan 76.7 44.6 17.5 49.3
18 University of Michigan United States 48.7 57.0 40.8 48.8
19 Cornell University United States 50.6 49.8 44.8 48.6
20 Georgia Institute of Technology United States 58.0 43.5 40.8 48.5
21= Ecole Polytechnique Fédérale de Lausanne Switzerland 46.2 42.3 47.5 45.4
21= University of Hong Kong Hong Kong 37.0 31.8 70.1 45.4
23 Columbia University United States 41.7 55.3 40.0 45.3
24 École Polytechnique France 38.8 50.6 47.7 45.0
25= University of Texas at Austin United States 48.5 43.8 41.3 44.9
25= Yale University United States 37.8 62.0 37.3 44.9
27 The University of Manchester United Kingdom 38.6 56.8 41.0 44.8
28= The Hong Kong University of Science and Technology Hong Kong 50.2 30.8 50.7 44.5
28= University of Illinois at Urbana-Champaign United States 56.9 36.3 36.0 44.5
30 University of British Columbia Canada 44.8 32.9 55.5 44.4
31 McGill University Canada 47.3 59.4 23.3 43.7
32= New York University (NYU) United States 16.2 43.0 79.8 43.3
32= Purdue University United States 43.4 45.6 40.7 43.3
34 The University of New South Wales Australia 38.9 51.6 36.5 42.0
35 Monash University Australia 35.0 52.5 40.2 41.8
36= Nanyang Technological University (NTU) Singapore 44.2 41.9 35.2 40.8
36= Peking University China 49.8 45.4 24.2 40.8
38 The University of Sydney Australia 44.0 47.0 29.9 40.7
39 Australian National University Australia 47.4 41.4 30.6 40.6
40 Tsinghua University China 56.5 37.0 22.3 40.4
41 Indian Institute of Technology Delhi (IITD) India 32.4 53.9 36.8 40.2
42= Kyoto University Japan 55.1 32.7 25.8 39.6
42= The University of Auckland New Zealand 36.1 57.7 26.2 39.6
44 University of California, San Diego (UCSD) United States 47.3 26.2 42.0 39.4
45 University of Edinburgh United Kingdom 33.4 52.1 34.5 39.3
46 University of Waterloo Canada 36.2 34.0 47.1 38.8
47 Delft University of Technology Netherlands 45.4 41.4 26.7 38.6
48 UCL (University College London) United Kingdom 38.6 42.3 33.2 38.1
49= Northwestern University United States 23.8 42.7 52.0 37.9
49= Seoul National University Korea, South 51.6 31.3 26.1 37.9
51-100 Brunel University United Kingdom 11.4 20.7 61.6
51-100 Case Western Reserve University United States 19.0 21.9 63.9
51-100 Chalmers University of Technology Sweden 31.0 32.8 42.7
51-100 The Chinese University of Hong Kong Hong Kong 41.6 26.4 35.7
51-100 City University of Hong Kong Hong Kong 27.0 25.2 52.9
51-100 Dartmouth College United States 6.1 20.0 77.7
51-100 Duke University United States 27.8 38.4 38.1
51-100 Eindhoven University of Technology Netherlands 28.0 27.7 42.0
51-100 Indian Institute of Technology Bombay (IITB) India 29.2 56.7 26.1
51-100 Indian Institute of Technology Kanpur (IITK) India 24.0 40.1 39.4
51-100 Indian Institute of Technology Kharagpur (IITKGP) India 21.3 39.2 32.4
51-100 Indian Institute of Technology Madras (IITM) India 23.7 48.1 36.3
51-100 Johns Hopkins University United States 31.3 32.1 23.8
51-100 KAIST - Korea Advanced Institute of Science & Technology Korea, South 50.1 24.4 25.0
51-100 Katholieke Universiteit Leuven Belgium 36.4 23.7 36.9
51-100 King’s College London (University of London) United Kingdom 29.2 29.5 48.2
51-100 KTH, Royal Institute of Technology Sweden 30.5 37.6 32.3
51-100 Ludwig-Maximilians-Universität München Germany 18.6 25.8 44.9
51-100 Lund University Sweden 25.8 39.4 42.7
51-100 National Taiwan University (NTU) Taiwan 48.6 16.6 28.8
51-100 National Technical University of Athens Greece 20.5 33.2 39.2
51-100 Ohio State University United States 19.2 38.2 36.9
51-100 Pennsylvania State University United States 23.7 41.2 39.6
51-100 Politecnico di Milano Italy 26.0 52.2 22.3
51-100 Queen's University of Belfast United Kingdom 15.0 36.6 39.1
51-100 Rheinisch-Westfälische Technische Hochschule Aachen Germany 31.6 43.4 20.9
51-100 Shanghai Jiao Tong University China 34.8 39.8 25.2
51-100 Technical University of Denmark Denmark 22.3 23.4 51.0
51-100 Technion - Israel Institute of Technology Israel 27.6 26.8 48.6
51-100 Technische Universität München Germany 39.5 47.5 23.5
51-100 Tokyo Institute of Technology Japan 55.7 33.8 15.7
51-100 Trinity College Dublin Ireland 24.4 37.5 51.5
51-100 Universidad de Buenos Aires Argentina 17.1 35.7 39.1
51-100 University of Alberta Canada 26.1 37.7 37.9
51-100 University of Birmingham United Kingdom 23.4 33.0 40.3
51-100 University of Bristol United Kingdom 23.3 47.8 22.7
51-100 University of California, Davis United States 21.2 23.1 50.8
51-100 University of California, Santa Barbara (UCSB) United States 43.0 19.8 40.5
51-100 University of Canterbury New Zealand 19.6 50.4 24.2
51-100 University of Copenhagen Denmark 16.5 27.9 63.5
51-100 University of Minnesota United States 18.8 31.7 64.4
51-100 University of Notre Dame United States 10.4 12.8 72.3
51-100 The University of Queensland Australia 27.0 46.9 37.0
51-100 University of Science and Technology of China China 31.1 34.9 36.1
51-100 University of Southampton United Kingdom 34.3 28.4 28.0
51-100 University of Southern California United States 23.2 19.2 47.4
51-100 The University of Warwick United Kingdom 22.6 53.8 26.8
51-100 University of Washington United States 34.6 31.6 41.5
51-100 University of Wisconsin-Madison United States 31.7 35.2 35.1
51-100 Uppsala University Sweden 21.4 24.4 43.6
51-100 Washington University in St. Louis United States 16.2 18.1 56.7
101-150 Aarhus University Denmark 11.3 25.9 46.7
101-150 Boston University United States 16.1 24.1 43.5
101-150 Brown University United States 18.0 29.2 36.7
101-150 Durham University United Kingdom 11.6 34.3 43.4
101-150 École Centrale de Paris France 13.0 26.9 50.5
101-150 Emory University United States 8.9 12.7 60.5
101-150 Fudan University China 30.7 30.5 22.9
101-150 Indian Institute of Science India 21.8 19.7 36.1
101-150 Massey University New Zealand 15.7 30.5 35.0
101-150 McMaster University Canada 18.6 23.2 35.1
101-150 Newcastle University United Kingdom 13.9 24.8 44.5
101-150 Osaka University Japan 43.9 21.1 15.0
101-150 Pohang University of Science And Technology (POSTECH) Korea, South 25.9 15.0 37.8
101-150 Politecnico di Torino Italy 21.9 31.3 24.8
101-150 Queen's University Canada 13.9 34.5 28.4
101-150 Rensselaer Polytechnic Institute United States 17.8 24.7 36.4
101-150 Rice University United States 17.8 22.3 49.2
101-150 RMIT University Australia 21.4 39.5 18.9
101-150 Rutgers, The State University of New Jersey, New Brunswick United States 13.7 12.1 58.5
101-150 Technische Universität Berlin Germany 28.9 28.9 28.0
101-150 Tel Aviv University Israel 16.8 14.7 46.8
101-150 Texas A&M University United States 23.7 27.6 26.0
101-150 Tohoku University Japan 33.5 19.6 17.6
101-150 Universidad Nacional Autónoma de México (UNAM) Mexico 23.2 30.9 27.9
101-150 Università di Bologna (UNIBO) Italy 18.3 39.3 28.9
101-150 Universitat de Barcelona (UB) Spain 11.7 35.5 36.5
101-150 Universität Karlsruhe Germany 25.0 32.1 23.3
101-150 Universität Stuttgart Germany 20.8 31.1 27.3
101-150 Université Catholique de Louvain (UCL) Belgium 19.8 26.6 33.5
101-150 University College Cork Ireland 17.3 31.2 35.0
101-150 University of Colorado at Boulder United States 15.8 28.4 30.2
101-150 University of Delaware United States 8.6 10.0 63.4
101-150 University of Florida United States 12.2 25.9 41.0
101-150 University of Glasgow United Kingdom 26.1 34.4 18.7
101-150 University of Groningen Netherlands 12.3 11.9 53.6
101-150 University of Illinois, Chicago (UIC) United States 12.6 11.3 58.6
101-150 University of Leeds United Kingdom 16.6 32.8 34.3
101-150 University of Maryland, College Park United States 24.2 22.5 40.4
101-150 University of Massachusetts, Amherst United States 13.8 20.0 45.5
101-150 University of Newcastle Australia 17.0 27.0 41.3
101-150 The University of Nottingham United Kingdom 20.1 23.8 33.0
101-150 The University of Sheffield United Kingdom 24.5 23.3 27.3
101-150 University of South Carolina United States 6.7 11.4 62.9
101-150 University of Surrey United Kingdom 20.4 23.5 31.2
101-150 University of Sussex United Kingdom 4.4 20.5 56.5
101-150 Virginia Polytechnic Institute (Virginia Tech) United States 22.8 27.4 39.0
101-150 The University of Western Australia Australia 19.3 34.8 23.7
101-150 University of Wollongong Australia 7.4 25.9 44.5
101-150 Warsaw University Poland 5.1 15.0 64.6
101-150 Zhejiang University China 29.4 19.6 21.1
151-200 Aalborg University Denmark 7.5 20.0 48.9
151-200 Arizona State University United States 21.3 14.0 27.0
151-200 Chulalongkorn University Thailand 25.1 15.4 30.4
151-200 City University London United Kingdom 5.7 29.2 34.8
151-200 Cranfield University United Kingdom 8.8 32.0 31.3
151-200 Dublin Institute of Technology Ireland 8.8 28.9 33.6
151-200 Griffith University Australia 9.8 27.5 31.3
151-200 The Hong Kong Polytechnic University Hong Kong 23.6 10.7 33.0
151-200 Indian Institute of Technology Roorkee (IITR) India 9.9 35.2 22.7
151-200 Istanbul Technical University Turkey 15.1 20.6 31.7
151-200 Korea University Korea, South 22.2 15.7 32.9
151-200 Lancaster University United Kingdom 10.8 28.9 27.9
151-200 Linköping University Sweden 18.9 17.0 31.9
151-200 Nanjing University China 20.6 20.8 21.8
151-200 National Tsing Hua University Taiwan 29.4 15.0 24.6
151-200 National University of Ireland, Galway Ireland 7.2 36.2 23.8
151-200 Norwegian University of Science And Technology Norway 8.2 22.0 40.4
151-200 Pontificia Universidad Católica de Chile Chile 15.4 25.5 27.9
151-200 Queen Mary, University of London (QMUL) United Kingdom 12.7 22.6 33.8
151-200 Queensland University of Technology Australia 16.9 30.9 24.9
151-200 Sapienza - Università di Roma Italy 19.5 24.0 28.5
151-200 Technische Universität Darmstadt Germany 18.2 30.7 24.3
151-200 Tecnológico de Monterrey (ITESM) Mexico 14.1 38.9 12.0
151-200 Universidad Autónoma de Madrid Spain 12.6 31.5 27.4
151-200 University Complutense Madrid Spain 10.3 26.2 34.7
151-200 Universidade Estadual de Campinas (Unicamp) Brazil 24.7 16.3 24.4
151-200 Universitat Autònoma de Barcelona Spain 13.4 19.2 36.1
151-200 Universität Bielefeld Germany 9.2 8.0 48.8
151-200 Universität Freiburg Germany 12.0 16.8 41.6
151-200 Universiti Malaya (UM) Malaysia 20.5 26.4 15.8
151-200 University College Dublin Ireland 14.9 36.1 21.4
151-200 University of Aberdeen United Kingdom 12.6 23.1 35.0
151-200 The University of Adelaide Australia 23.1 35.9 12.3
151-200 University of Basel Switzerland 10.1 17.1 43.5
151-200 University of Bath United Kingdom 11.2 35.2 29.1
151-200 University of Calgary Canada 15.9 31.1 19.0
151-200 University of California, Riverside United States 6.7 3.7 62.1
151-200 University of Delhi India 10.4 43.8 20.6
151-200 University of Ghent Belgium 21.9 23.2 26.9
151-200 University of Liverpool United Kingdom 16.4 25.4 22.7
151-200 University of South Australia Australia 12.4 25.1 28.8
151-200 University of Strathclyde United Kingdom 18.3 29.3 18.6
151-200 University of Technology, Sydney Australia 16.7 33.9 20.7
151-200 University of Victoria Canada 11.3 9.9 49.0
151-200 University of Virginia United States 10.1 23.3 32.4
151-200 University of York United Kingdom 15.4 25.5 24.9
151-200 University of Zurich Switzerland 10.3 11.4 44.5
151-200 VU University Amsterdam Netherlands 9.4 11.4 54.4
151-200 Waseda University Japan 28.1 30.4 9.4
151-200 Yonsei University Korea, South 19.1 19.5 26.9
Rank Title Country Academic Employer Citations Score
1 Massachusetts Institute of Technology (MIT) United States 100.0 84.9 56.8 82.5
2 Stanford University United States 91.3 73.9 69.7 79.6
3 University of Cambridge United Kingdom 83.0 93.8 43.1 74.3
4 University of California, Berkeley (UCB) United States 92.5 64.4 55.9 73.1
5 University of Oxford United Kingdom 66.0 94.1 61.3 73.0
6 Harvard University United States 65.9 100.0 52.1 72.0
7 California Institute of Technology (Caltech) United States 72.9 43.8 76.1 65.1
8 University of California, Los Angeles (UCLA) United States 64.2 63.7 63.4 63.8
9 Imperial College London United Kingdom 66.1 65.7 48.3 60.6
10 National University of Singapore (NUS) Singapore 63.2 57.4 44.7 55.9
11 ETH Zurich (Swiss Federal Institute of Technology) Switzerland 62.2 49.9 50.6 55.0
12 Princeton University United States 59.9 40.6 56.8 53.2
13 University of Toronto Canada 61.1 45.5 45.3 51.7
14 University of Pennsylvania United States 33.8 55.0 70.4 51.1
15 The University of Melbourne Australia 47.0 68.1 38.5 50.8
16 Carnegie Mellon University United States 57.6 41.4 46.4 49.4
17 The University of Tokyo Japan 76.7 44.6 17.5 49.3
18 University of Michigan United States 48.7 57.0 40.8 48.8
19 Cornell University United States 50.6 49.8 44.8 48.6
20 Georgia Institute of Technology United States 58.0 43.5 40.8 48.5
21= Ecole Polytechnique Fédérale de Lausanne Switzerland 46.2 42.3 47.5 45.4
21= University of Hong Kong Hong Kong 37.0 31.8 70.1 45.4
23 Columbia University United States 41.7 55.3 40.0 45.3
24 École Polytechnique France 38.8 50.6 47.7 45.0
25= University of Texas at Austin United States 48.5 43.8 41.3 44.9
25= Yale University United States 37.8 62.0 37.3 44.9
27 The University of Manchester United Kingdom 38.6 56.8 41.0 44.8
28= The Hong Kong University of Science and Technology Hong Kong 50.2 30.8 50.7 44.5
28= University of Illinois at Urbana-Champaign United States 56.9 36.3 36.0 44.5
30 University of British Columbia Canada 44.8 32.9 55.5 44.4
31 McGill University Canada 47.3 59.4 23.3 43.7
32= New York University (NYU) United States 16.2 43.0 79.8 43.3
32= Purdue University United States 43.4 45.6 40.7 43.3
34 The University of New South Wales Australia 38.9 51.6 36.5 42.0
35 Monash University Australia 35.0 52.5 40.2 41.8
36= Nanyang Technological University (NTU) Singapore 44.2 41.9 35.2 40.8
36= Peking University China 49.8 45.4 24.2 40.8
38 The University of Sydney Australia 44.0 47.0 29.9 40.7
39 Australian National University Australia 47.4 41.4 30.6 40.6
40 Tsinghua University China 56.5 37.0 22.3 40.4
41 Indian Institute of Technology Delhi (IITD) India 32.4 53.9 36.8 40.2
42= Kyoto University Japan 55.1 32.7 25.8 39.6
42= The University of Auckland New Zealand 36.1 57.7 26.2 39.6
44 University of California, San Diego (UCSD) United States 47.3 26.2 42.0 39.4
45 University of Edinburgh United Kingdom 33.4 52.1 34.5 39.3
46 University of Waterloo Canada 36.2 34.0 47.1 38.8
47 Delft University of Technology Netherlands 45.4 41.4 26.7 38.6
48 UCL (University College London) United Kingdom 38.6 42.3 33.2 38.1
49= Northwestern University United States 23.8 42.7 52.0 37.9
49= Seoul National University Korea, South 51.6 31.3 26.1 37.9
51-100 Brunel University United Kingdom 11.4 20.7 61.6
51-100 Case Western Reserve University United States 19.0 21.9 63.9
51-100 Chalmers University of Technology Sweden 31.0 32.8 42.7
51-100 The Chinese University of Hong Kong Hong Kong 41.6 26.4 35.7
51-100 City University of Hong Kong Hong Kong 27.0 25.2 52.9
51-100 Dartmouth College United States 6.1 20.0 77.7
51-100 Duke University United States 27.8 38.4 38.1
51-100 Eindhoven University of Technology Netherlands 28.0 27.7 42.0
51-100 Indian Institute of Technology Bombay (IITB) India 29.2 56.7 26.1
51-100 Indian Institute of Technology Kanpur (IITK) India 24.0 40.1 39.4
51-100 Indian Institute of Technology Kharagpur (IITKGP) India 21.3 39.2 32.4
51-100 Indian Institute of Technology Madras (IITM) India 23.7 48.1 36.3
51-100 Johns Hopkins University United States 31.3 32.1 23.8
51-100 KAIST - Korea Advanced Institute of Science & Technology Korea, South 50.1 24.4 25.0
51-100 Katholieke Universiteit Leuven Belgium 36.4 23.7 36.9
51-100 King’s College London (University of London) United Kingdom 29.2 29.5 48.2
51-100 KTH, Royal Institute of Technology Sweden 30.5 37.6 32.3
51-100 Ludwig-Maximilians-Universität München Germany 18.6 25.8 44.9
51-100 Lund University Sweden 25.8 39.4 42.7
51-100 National Taiwan University (NTU) Taiwan 48.6 16.6 28.8
51-100 National Technical University of Athens Greece 20.5 33.2 39.2
51-100 Ohio State University United States 19.2 38.2 36.9
51-100 Pennsylvania State University United States 23.7 41.2 39.6
51-100 Politecnico di Milano Italy 26.0 52.2 22.3
51-100 Queen's University of Belfast United Kingdom 15.0 36.6 39.1
51-100 Rheinisch-Westfälische Technische Hochschule Aachen Germany 31.6 43.4 20.9
51-100 Shanghai Jiao Tong University China 34.8 39.8 25.2
51-100 Technical University of Denmark Denmark 22.3 23.4 51.0
51-100 Technion - Israel Institute of Technology Israel 27.6 26.8 48.6
51-100 Technische Universität München Germany 39.5 47.5 23.5
51-100 Tokyo Institute of Technology Japan 55.7 33.8 15.7
51-100 Trinity College Dublin Ireland 24.4 37.5 51.5
51-100 Universidad de Buenos Aires Argentina 17.1 35.7 39.1
51-100 University of Alberta Canada 26.1 37.7 37.9
51-100 University of Birmingham United Kingdom 23.4 33.0 40.3
51-100 University of Bristol United Kingdom 23.3 47.8 22.7
51-100 University of California, Davis United States 21.2 23.1 50.8
51-100 University of California, Santa Barbara (UCSB) United States 43.0 19.8 40.5
51-100 University of Canterbury New Zealand 19.6 50.4 24.2
51-100 University of Copenhagen Denmark 16.5 27.9 63.5
51-100 University of Minnesota United States 18.8 31.7 64.4
51-100 University of Notre Dame United States 10.4 12.8 72.3
51-100 The University of Queensland Australia 27.0 46.9 37.0
51-100 University of Science and Technology of China China 31.1 34.9 36.1
51-100 University of Southampton United Kingdom 34.3 28.4 28.0
51-100 University of Southern California United States 23.2 19.2 47.4
51-100 The University of Warwick United Kingdom 22.6 53.8 26.8
51-100 University of Washington United States 34.6 31.6 41.5
51-100 University of Wisconsin-Madison United States 31.7 35.2 35.1
51-100 Uppsala University Sweden 21.4 24.4 43.6
51-100 Washington University in St. Louis United States 16.2 18.1 56.7
101-150 Aarhus University Denmark 11.3 25.9 46.7
101-150 Boston University United States 16.1 24.1 43.5
101-150 Brown University United States 18.0 29.2 36.7
101-150 Durham University United Kingdom 11.6 34.3 43.4
101-150 École Centrale de Paris France 13.0 26.9 50.5
101-150 Emory University United States 8.9 12.7 60.5
101-150 Fudan University China 30.7 30.5 22.9
101-150 Indian Institute of Science India 21.8 19.7 36.1
101-150 Massey University New Zealand 15.7 30.5 35.0
101-150 McMaster University Canada 18.6 23.2 35.1
101-150 Newcastle University United Kingdom 13.9 24.8 44.5
101-150 Osaka University Japan 43.9 21.1 15.0
101-150 Pohang University of Science And Technology (POSTECH) Korea, South 25.9 15.0 37.8
101-150 Politecnico di Torino Italy 21.9 31.3 24.8
101-150 Queen's University Canada 13.9 34.5 28.4
101-150 Rensselaer Polytechnic Institute United States 17.8 24.7 36.4
101-150 Rice University United States 17.8 22.3 49.2
101-150 RMIT University Australia 21.4 39.5 18.9
101-150 Rutgers, The State University of New Jersey, New Brunswick United States 13.7 12.1 58.5
101-150 Technische Universität Berlin Germany 28.9 28.9 28.0
101-150 Tel Aviv University Israel 16.8 14.7 46.8
101-150 Texas A&M University United States 23.7 27.6 26.0
101-150 Tohoku University Japan 33.5 19.6 17.6
101-150 Universidad Nacional Autónoma de México (UNAM) Mexico 23.2 30.9 27.9
101-150 Università di Bologna (UNIBO) Italy 18.3 39.3 28.9
101-150 Universitat de Barcelona (UB) Spain 11.7 35.5 36.5
101-150 Universität Karlsruhe Germany 25.0 32.1 23.3
101-150 Universität Stuttgart Germany 20.8 31.1 27.3
101-150 Université Catholique de Louvain (UCL) Belgium 19.8 26.6 33.5
101-150 University College Cork Ireland 17.3 31.2 35.0
101-150 University of Colorado at Boulder United States 15.8 28.4 30.2
101-150 University of Delaware United States 8.6 10.0 63.4
101-150 University of Florida United States 12.2 25.9 41.0
101-150 University of Glasgow United Kingdom 26.1 34.4 18.7
101-150 University of Groningen Netherlands 12.3 11.9 53.6
101-150 University of Illinois, Chicago (UIC) United States 12.6 11.3 58.6
101-150 University of Leeds United Kingdom 16.6 32.8 34.3
101-150 University of Maryland, College Park United States 24.2 22.5 40.4
101-150 University of Massachusetts, Amherst United States 13.8 20.0 45.5
101-150 University of Newcastle Australia 17.0 27.0 41.3
101-150 The University of Nottingham United Kingdom 20.1 23.8 33.0
101-150 The University of Sheffield United Kingdom 24.5 23.3 27.3
101-150 University of South Carolina United States 6.7 11.4 62.9
101-150 University of Surrey United Kingdom 20.4 23.5 31.2
101-150 University of Sussex United Kingdom 4.4 20.5 56.5
101-150 Virginia Polytechnic Institute (Virginia Tech) United States 22.8 27.4 39.0
101-150 The University of Western Australia Australia 19.3 34.8 23.7
101-150 University of Wollongong Australia 7.4 25.9 44.5
101-150 Warsaw University Poland 5.1 15.0 64.6
101-150 Zhejiang University China 29.4 19.6 21.1
151-200 Aalborg University Denmark 7.5 20.0 48.9
151-200 Arizona State University United States 21.3 14.0 27.0
151-200 Chulalongkorn University Thailand 25.1 15.4 30.4
151-200 City University London United Kingdom 5.7 29.2 34.8
151-200 Cranfield University United Kingdom 8.8 32.0 31.3
151-200 Dublin Institute of Technology Ireland 8.8 28.9 33.6
151-200 Griffith University Australia 9.8 27.5 31.3
151-200 The Hong Kong Polytechnic University Hong Kong 23.6 10.7 33.0
151-200 Indian Institute of Technology Roorkee (IITR) India 9.9 35.2 22.7
151-200 Istanbul Technical University Turkey 15.1 20.6 31.7
151-200 Korea University Korea, South 22.2 15.7 32.9
151-200 Lancaster University United Kingdom 10.8 28.9 27.9
151-200 Linköping University Sweden 18.9 17.0 31.9
151-200 Nanjing University China 20.6 20.8 21.8
151-200 National Tsing Hua University Taiwan 29.4 15.0 24.6
151-200 National University of Ireland, Galway Ireland 7.2 36.2 23.8
151-200 Norwegian University of Science And Technology Norway 8.2 22.0 40.4
151-200 Pontificia Universidad Católica de Chile Chile 15.4 25.5 27.9
151-200 Queen Mary, University of London (QMUL) United Kingdom 12.7 22.6 33.8
151-200 Queensland University of Technology Australia 16.9 30.9 24.9
151-200 Sapienza - Università di Roma Italy 19.5 24.0 28.5
151-200 Technische Universität Darmstadt Germany 18.2 30.7 24.3
151-200 Tecnológico de Monterrey (ITESM) Mexico 14.1 38.9 12.0
151-200 Universidad Autónoma de Madrid Spain 12.6 31.5 27.4
151-200 University Complutense Madrid Spain 10.3 26.2 34.7
151-200 Universidade Estadual de Campinas (Unicamp) Brazil 24.7 16.3 24.4
151-200 Universitat Autònoma de Barcelona Spain 13.4 19.2 36.1
151-200 Universität Bielefeld Germany 9.2 8.0 48.8
151-200 Universität Freiburg Germany 12.0 16.8 41.6
151-200 Universiti Malaya (UM) Malaysia 20.5 26.4 15.8
151-200 University College Dublin Ireland 14.9 36.1 21.4
151-200 University of Aberdeen United Kingdom 12.6 23.1 35.0
151-200 The University of Adelaide Australia 23.1 35.9 12.3
151-200 University of Basel Switzerland 10.1 17.1 43.5
151-200 University of Bath United Kingdom 11.2 35.2 29.1
151-200 University of Calgary Canada 15.9 31.1 19.0
151-200 University of California, Riverside United States 6.7 3.7 62.1
151-200 University of Delhi India 10.4 43.8 20.6
151-200 University of Ghent Belgium 21.9 23.2 26.9
151-200 University of Liverpool United Kingdom 16.4 25.4 22.7
151-200 University of South Australia Australia 12.4 25.1 28.8
151-200 University of Strathclyde United Kingdom 18.3 29.3 18.6
151-200 University of Technology, Sydney Australia 16.7 33.9 20.7
151-200 University of Victoria Canada 11.3 9.9 49.0
151-200 University of Virginia United States 10.1 23.3 32.4
151-200 University of York United Kingdom 15.4 25.5 24.9
151-200 University of Zurich Switzerland 10.3 11.4 44.5
151-200 VU University Amsterdam Netherlands 9.4 11.4 54.4
151-200 Waseda University Japan 28.1 30.4 9.4
151-200 Yonsei University Korea, South 19.1 19.5 26.9
Top 10 companies for Electrical Engineers in India?
The Top 10 companies for Electrical Engineers in India Are As Given Below. So, If You Are Interested To Get Job In these Companies Then Please Check These Given Companies -
Bajaj International Private Ltd
Bharat Heavy Electricals Limited (BHEL)
Crompton Greaves Limited (CGL)
Dev Denso Power Ltd
Info Edge (India) Ltd
Penguin Engineering Ltd
Bristol Fire Engineering
Kelvin Electrical
Siemens Ltd
Wipro Lighting.
Bajaj International Private Ltd
Bharat Heavy Electricals Limited (BHEL)
Crompton Greaves Limited (CGL)
Dev Denso Power Ltd
Info Edge (India) Ltd
Penguin Engineering Ltd
Bristol Fire Engineering
Kelvin Electrical
Siemens Ltd
Wipro Lighting.
auto transformer
In an autotransformer portions of the same winding act as both the primary and secondary. The winding has at least three taps where electrical connections are made. An autotransformer can be smaller, lighter and cheaper than a standard dual-winding transformer however the autotransformer does not provide electrical isolation.
Autotransformers are often used to step up or down between voltages in the 110-117-120 volt range and voltages in the 220-230-240 volt range, e.g., to output either 110 or 120V (with taps) from 230V input, allowing equipment from a 100 or 120V region to be used in a 230V region.
A variable autotransformer is made by exposing part of the winding coils and making the secondary connection through a sliding brush, giving a variable turns ratio.[48] Such a device is often referred to by the trademark name Variac.
Autotransformers are often used to step up or down between voltages in the 110-117-120 volt range and voltages in the 220-230-240 volt range, e.g., to output either 110 or 120V (with taps) from 230V input, allowing equipment from a 100 or 120V region to be used in a 230V region.
A variable autotransformer is made by exposing part of the winding coils and making the secondary connection through a sliding brush, giving a variable turns ratio.[48] Such a device is often referred to by the trademark name Variac.
electrical transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF), or "voltage", in the secondary winding. This effect is called mutual induction.
If a load is connected to the secondary, an electric current will flow in the secondary winding and electrical energy will be transferred from the primary circuit through the transformer to the load. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in proportion to the primary voltage (Vp), and is given by the ratio of the number of turns in the secondary (Ns) to the number of turns in the primary (Np) as follows:
By appropriate selection of the ratio of turns, a transformer thus allows an alternating current (AC) voltage to be "stepped up" by making Ns greater than Np, or "stepped down" by making Ns less than Np.
In the vast majority of transformers, the windings are coils wound around a ferromagnetic core, air-core transformers being a notable exception.
Transformers range in size from a thumbnail-sized coupling transformer hidden inside a stage microphone to huge units weighing hundreds of tons used to interconnect portions of power grids. All operate with the same basic principles, although the range of designs is wide. While new technologies have eliminated the need for transformers in some electronic circuits, transformers are still found in nearly all electronic devices designed for household ("mains") voltage. Transformers are essential for high-voltage electric power transmission, which makes long-distance transmission economically practical.
Thursday 27 October 2011
watt steam engine
electrical machine
An electrical machine is the generic name for a device that converts mechanical energy to electrical energy, converts electrical energy to mechanical energy, or changes alternating current from one voltage level to a different voltage level.
Electrical machines as employed in industry fall into three categories according to how they convert energy. Generators convert mechanical energy to electrical energy. Motors convert electrical energy to mechanical energy. Transformers change the voltage of alternating current.
electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical power supply. It now covers a range of subtopics including power, electronics, control systems, signal processing and telecommunications.
Electrical engineering may include electronic engineering. Where a distinction is made, usually outside of the United States, electrical engineering is considered to deal with the problems associated with large-scale electrical systems such as power transmission and motor control, whereas electronic engineering deals with the study of small-scale electronic systems including computers and integrated circuits.[1] Alternatively, electrical engineers are usually concerned with using electricity to transmit energy, while electronic engineers are concerned with using electricity to process information. More recently, the distinction has become blurred by the growth of power electronics.
History
The discoveries of Michael Faraday formed the foundation of electric motor technology.Electricity has been a subject of scientific interest since at least the early 17th century. The first electrical engineer was probably William Gilbert who designed the versorium: a device that detected the presence of statically charged objects. He was also the first to draw a clear distinction between magnetism and static electricity and is credited with establishing the term electricity.[2] In 1775 Alessandro Volta's scientific experimentations devised the electrophorus, a device that produced a static electric charge, and by 1800 Volta developed the voltaic pile, a forerunner of the electric battery.[3]
However, it was not until the 19th century that research into the subject started to intensify. Notable developments in this century include the work of Georg Ohm, who in 1827 quantified the relationship between the electric current and potential difference in a conductor, Michael Faraday, the discoverer of electromagnetic induction in 1831, and James Clerk Maxwell, who in 1873 published a unified theory of electricity and magnetism in his treatise Electricity and Magnetism.[4]
Thomas Edison built the world's first large-scale electrical supply network.During these years, the study of electricity was largely considered to be a subfield of physics. It was not until the late 19th century that universities started to offer degrees in electrical engineering. The Darmstadt University of Technology founded the first chair and the first faculty of electrical engineering worldwide in 1882. In the same year, under Professor Charles Cross, the Massachusetts Institute of Technology began offering the first option of Electrical Engineering within a physics department.[5] In 1883 Darmstadt University of Technology and Cornell University introduced the world's first courses of study in electrical engineering, and in 1885 the University College London founded the first chair of electrical engineering in the United Kingdom.[6] The University of Missouri subsequently established the first department of electrical engineering in the United States in 1886.[7]
Nikola Tesla made long-distance electrical transmission networks possible.During this period, the work concerning electrical engineering increased dramatically. In 1882, Edison switched on the world's first large-scale electrical supply network that provided 110 volts direct current to fifty-nine customers in lower Manhattan. In 1884 Sir Charles Parsons invented the steam turbine which today generates about 80 percent of the electric power in the world using a variety of heat sources. In 1887, Nikola Tesla filed a number of patents related to a competing form of power distribution known as alternating current. In the following years a bitter rivalry between Tesla and Edison, known as the "War of Currents", took place over the preferred method of distribution. AC eventually replaced DC for generation and power distribution, enormously extending the range and improving the safety and efficiency of power distribution.
The efforts of the two did much to further electrical engineering—Tesla's work on induction motors and polyphase systems influenced the field for years to come, while Edison's work on telegraphy and his development of the stock ticker proved lucrative for his company, which ultimately became General Electric. However, by the end of the 19th century, other key figures in the progress of electrical engineering were beginning to emerge.[8]
In 1941 Konrad Zuse presented the Z3, the world's first fully functional and programmable computer.[16] In 1946 the ENIAC (Electronic Numerical Integrator and Computer) of John Presper Eckert and John Mauchly followed, beginning the computing era. The arithmetic performance of these machines allowed engineers to develop completely new technologies and achieve new objectives, including the Apollo missions and the NASA moon landing.[17]
The invention of the transistor in 1947 by William B. Shockley, John Bardeen and Walter Brattain opened the door for more compact devices and led to the development of the integrated circuit in 1958 by Jack Kilby and independently in 1959 by Robert Noyce.[18] Starting in 1968, Ted Hoff and a team at Intel invented the first commercial microprocessor, which presaged the personal computer. The Intel 4004 was a 4-bit processor released in 1971, but in 1973 the Intel 8080, an 8-bit processor, made the first personal computer, the Altair 8800, possible.[19]
Some electrical engineers choose to pursue a postgraduate degree such as a Master of Engineering/Master of Science (M.Eng./M.Sc.), a Master of Engineering Management, a Doctor of Philosophy (Ph.D.) in Engineering, an Engineering Doctorate (Eng.D.), or an Engineer's degree. The Master and Engineer's degree may consist of either research, coursework or a mixture of the two. The Doctor of Philosophy and Engineering Doctorate degrees consist of a significant research component and are often viewed as the entry point to academia. In the United Kingdom and various other European countries, the Master of Engineering is often considered an undergraduate degree of slightly longer duration than the Bachelor of Engineering.[20]
The advantages of certification vary depending upon location. For example, in the United States and Canada "only a licensed engineer may seal engineering work for public and private clients".[21] This requirement is enforced by state and provincial legislation such as Quebec's Engineers Act.[22] In other countries, no such legislation exists. Practically all certifying bodies maintain a code of ethics that they expect all members to abide by or risk expulsion.[23] In this way these organizations play an important role in maintaining ethical standards for the profession. Even in jurisdictions where certification has little or no legal bearing on work, engineers are subject to contract law. In cases where an engineer's work fails he or she may be subject to the tort of negligence and, in extreme cases, the charge of criminal negligence. An engineer's work must also comply with numerous other rules and regulations such as building codes and legislation pertaining to environmental law.
Professional bodies of note for electrical engineers include the Institute of Electrical and Electronics Engineers (IEEE) and the Institution of Engineering and Technology (IET). The IEEE claims to produce 30% of the world's literature in electrical engineering, has over 360,000 members worldwide and holds over 3,000 conferences annually.[24] The IET publishes 21 journals, has a worldwide membership of over 150,000, and claims to be the largest professional engineering society in Europe.[25][26] Obsolescence of technical skills is a serious concern for electrical engineers. Membership and participation in technical societies, regular reviews of periodicals in the field and a habit of continued learning are therefore essential to maintaining proficiency.[27]
In Australia, Canada and the United States electrical engineers make up around 0.25% of the labor force (see note). Outside of Europe and North America, engineering graduates per-capita, and hence probably electrical engineering graduates also, are most numerous in Taiwan, Japan, and South Korea.[28]
Satellite communications is one of many projects an electrical engineer might work on.Fundamental to the discipline are the sciences of physics and mathematics as these help to obtain both a qualitative and quantitative description of how such systems will work. Today most engineering work involves the use of computers and it is commonplace to use computer-aided design programs when designing electrical systems. Nevertheless, the ability to sketch ideas is still invaluable for quickly communicating with others.
Although most electrical engineers will understand basic circuit theory (that is the interactions of elements such as resistors, capacitors, diodes, transistors and inductors in a circuit), the theories employed by engineers generally depend upon the work they do. For example, quantum mechanics and solid state physics might be relevant to an engineer working on VLSI (the design of integrated circuits), but are largely irrelevant to engineers working with macroscopic electrical systems. Even circuit theory may not be relevant to a person designing telecommunication systems that use off-the-shelf components. Perhaps the most important technical skills for electrical engineers are reflected in university programs, which emphasize strong numerical skills, computer literacy and the ability to understand the technical language and concepts that relate to electrical engineering.
For many engineers, technical work accounts for only a fraction of the work they do. A lot of time may also be spent on tasks such as discussing proposals with clients, preparing budgets and determining project schedules.[30] Many senior engineers manage a team of technicians or other engineers and for this reason project management skills are important. Most engineering projects involve some form of documentation and strong written communication skills are therefore very important.
The workplaces of electrical engineers are just as varied as the types of work they do. Electrical engineers may be found in the pristine lab environment of a fabrication plant, the offices of a consulting firm or on site at a mine. During their working life, electrical engineers may find themselves supervising a wide range of individuals including scientists, electricians, computer programmers and other engineers.
Control engineering focuses on the modeling of a diverse range of dynamic systems and the design of controllers that will cause these systems to behave in the desired manner. To implement such controllers electrical engineers may use electrical circuits, digital signal processors, microcontrollers and PLCs (Programmable Logic Controllers). Control engineering has a wide range of applications from the flight and propulsion systems of commercial airliners to the cruise control present in many modern automobiles. It also plays an important role in industrial automation.
Control engineers often utilize feedback when designing control systems. For example, in an automobile with cruise control the vehicle's speed is continuously monitored and fed back to the system which adjusts the motor's power output accordingly. Where there is regular feedback, control theory can be used to determine how the system responds to such feedback.
Prior to the second world war, the subject was commonly known as radio engineering and basically was restricted to aspects of communications and radar, commercial radio and early television. Later, in post war years, as consumer devices began to be developed, the field grew to include modern television, audio systems, computers and microprocessors. In the mid-to-late 1950s, the term radio engineering gradually gave way to the name electronic engineering.
Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by humans. These discrete circuits consumed much space and power and were limited in speed, although they are still common in some applications. By contrast, integrated circuits packed a large number—often millions—of tiny electrical components, mainly transistors, into a small chip around the size of a coin. This allowed for the powerful computers and other electronic devices we see today.
Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon (at higher frequencies, compound semiconductors like gallium arsenide and indium phosphide) to obtain the desired transport of electronic charge and control of current. The field of microelectronics involves a significant amount of chemistry and material science and requires the electronic engineer working in the field to have a very good working knowledge of the effects of quantum mechanics.
A Bayer filter on a CCD requires signal processing to get a red, green, and blue value at each pixel.Signal processing deals with the analysis and manipulation of signals. Signals can be either analog, in which case the signal varies continuously according to the information, or digital, in which case the signal varies according to a series of discrete values representing the information. For analog signals, signal processing may involve the amplification and filtering of audio signals for audio equipment or the modulation and demodulation of signals for telecommunications. For digital signals, signal processing may involve the compression, error detection and error correction of digitally sampled signals.
Signal Processing is a very mathematically oriented and intensive area forming the core of digital signal processing and it is rapidly expanding with new applications in every field of electrical engineering such as communications, control, radar, TV/Audio/Video engineering, power electronics and bio-medical engineering as many already existing analog systems are replaced with their digital counterparts.
Although in the classical era, analog signal processing only provided a mathematical description of a system to be designed, which is actually implemented by the analog hardware engineers, Digital Signal Processing both provides a mathematical description of the systems to be designed and also actually implements them (either by software programming or by hardware embedding) without much dependency on hardware issues, which exponentiates the importance and success of DSP engineering.
The deep and strong relations between signals and the information they carry makes signal processing equivalent of information processing. Which is the reason why the field finds so many diversified applications. DSP processor ICs are found in every type of modern electronic systems and products including, SDTV | HDTV sets, radios and mobile communication devices, Hi-Fi audio equipments, Dolby noise reduction algorithms, GSM mobile phones, mp3 multimedia players, camcorders and digital cameras, automobile control systems, noise cancelling headphones, digital spectrum analyzers, intelligent missile guidance, radar, GPS based cruise control systems and all kinds of image processing, video processing, audio processing and speech processing systems.
Satellite dishes are a crucial component in the analysis of satellite information.Telecommunications engineering focuses on the transmission of information across a channel such as a coax cable, optical fiber or free space. Transmissions across free space require information to be encoded in a carrier wave in order to shift the information to a carrier frequency suitable for transmission, this is known as modulation. Popular analog modulation techniques include amplitude modulation and frequency modulation. The choice of modulation affects the cost and performance of a system and these two factors must be balanced carefully by the engineer.
Once the transmission characteristics of a system are determined, telecommunication engineers design the transmitters and receivers needed for such systems. These two are sometimes combined to form a two-way communication device known as a transceiver. A key consideration in the design of transmitters is their power consumption as this is closely related to their signal strength. If the signal strength of a transmitter is insufficient the signal's information will be corrupted by noise.
Flight instruments provide pilots the tools to control aircraft analytically.Instrumentation engineering deals with the design of devices to measure physical quantities such as pressure, flow and temperature. The design of such instrumentation requires a good understanding of physics that often extends beyond electromagnetic theory. For example, flight instruments measure variables such as wind speed and altitude to enable pilots the control of aircraft analytically. Similarly, thermocouples use the Peltier-Seebeck effect to measure the temperature difference between two points.
Often instrumentation is not used by itself, but instead as the sensors of larger electrical systems. For example, a thermocouple might be used to help ensure a furnace's temperature remains constant. For this reason, instrumentation engineering is often viewed as the counterpart of control engineering.
Supercomputers are used in fields as diverse as computational biology and geographic information systems.Computer engineering deals with the design of computers and computer systems. This may involve the design of new hardware, the design of PDAs and supercomputers or the use of computers to control an industrial plant. Computer engineers may also work on a system's software. However, the design of complex software systems is often the domain of software engineering, which is usually considered a separate discipline. Desktop computers represent a tiny fraction of the devices a computer engineer might work on, as computer-like architectures are now found in a range of devices including video game consoles and DVD players.
The term mechatronics is typically used to refer to macroscopic systems but futurists have predicted the emergence of very small electromechanical devices. Already such small devices, known as Microelectromechanical systems (MEMS), are used in automobiles to tell airbags when to deploy, in digital projectors to create sharper images and in inkjet printers to create nozzles for high definition printing. In the future it is hoped the devices will help build tiny implantable medical devices and improve optical communication.[31]
Biomedical engineering is another related discipline, concerned with the design of medical equipment. This includes fixed equipment such as ventilators, MRI scanners and electrocardiograph monitors as well as mobile equipment such as cochlear implants, artificial pacemakers and artificial hearts.
Electrical engineering may include electronic engineering. Where a distinction is made, usually outside of the United States, electrical engineering is considered to deal with the problems associated with large-scale electrical systems such as power transmission and motor control, whereas electronic engineering deals with the study of small-scale electronic systems including computers and integrated circuits.[1] Alternatively, electrical engineers are usually concerned with using electricity to transmit energy, while electronic engineers are concerned with using electricity to process information. More recently, the distinction has become blurred by the growth of power electronics.
History
Main article: History of electrical engineering
However, it was not until the 19th century that research into the subject started to intensify. Notable developments in this century include the work of Georg Ohm, who in 1827 quantified the relationship between the electric current and potential difference in a conductor, Michael Faraday, the discoverer of electromagnetic induction in 1831, and James Clerk Maxwell, who in 1873 published a unified theory of electricity and magnetism in his treatise Electricity and Magnetism.[4]
The efforts of the two did much to further electrical engineering—Tesla's work on induction motors and polyphase systems influenced the field for years to come, while Edison's work on telegraphy and his development of the stock ticker proved lucrative for his company, which ultimately became General Electric. However, by the end of the 19th century, other key figures in the progress of electrical engineering were beginning to emerge.[8]
[edit] Modern developments
During the development of radio, many scientists and inventors contributed to radio technology and electronics. In his classic UHF experiments of 1888, Heinrich Hertz transmitted (via a spark-gap transmitter) and detected radio waves using electrical equipment. In 1895, Nikola Tesla was able to detect signals from the transmissions of his New York lab at West Point (a distance of 80.4 km / 49.95 miles).[9] In 1897, Karl Ferdinand Braun introduced the cathode ray tube as part of an oscilloscope, a crucial enabling technology for electronic television.[10] John Fleming invented the first radio tube, the diode, in 1904. Two years later, Robert von Lieben and Lee De Forest independently developed the amplifier tube, called the triode.[11] In 1895, Guglielmo Marconi furthered the art of hertzian wireless methods. Early on, he sent wireless signals over a distance of one and a half miles. In December 1901, he sent wireless waves that were not affected by the curvature of the Earth. Marconi later transmitted the wireless signals across the Atlantic between Poldhu, Cornwall, and St. John's, Newfoundland, a distance of 2,100 miles (3,400 km).[12] In 1920 Albert Hull developed the magnetron which would eventually lead to the development of the microwave oven in 1946 by Percy Spencer.[13][14] In 1934 the British military began to make strides toward radar (which also uses the magnetron) under the direction of Dr Wimperis, culminating in the operation of the first radar station at Bawdsey in August 1936.[15]In 1941 Konrad Zuse presented the Z3, the world's first fully functional and programmable computer.[16] In 1946 the ENIAC (Electronic Numerical Integrator and Computer) of John Presper Eckert and John Mauchly followed, beginning the computing era. The arithmetic performance of these machines allowed engineers to develop completely new technologies and achieve new objectives, including the Apollo missions and the NASA moon landing.[17]
The invention of the transistor in 1947 by William B. Shockley, John Bardeen and Walter Brattain opened the door for more compact devices and led to the development of the integrated circuit in 1958 by Jack Kilby and independently in 1959 by Robert Noyce.[18] Starting in 1968, Ted Hoff and a team at Intel invented the first commercial microprocessor, which presaged the personal computer. The Intel 4004 was a 4-bit processor released in 1971, but in 1973 the Intel 8080, an 8-bit processor, made the first personal computer, the Altair 8800, possible.[19]
[edit] Education
Electrical engineers typically possess an academic degree with a major in electrical engineering. The length of study for such a degree is usually four or five years and the completed degree may be designated as a Bachelor of Engineering, Bachelor of Science, Bachelor of Technology or Bachelor of Applied Science depending upon the university. The degree generally includes units covering physics, mathematics, computer science, project management and specific topics in electrical engineering. Initially such topics cover most, if not all, of the sub-disciplines of electrical engineering. Students then choose to specialize in one or more sub-disciplines towards the end of the degree.Some electrical engineers choose to pursue a postgraduate degree such as a Master of Engineering/Master of Science (M.Eng./M.Sc.), a Master of Engineering Management, a Doctor of Philosophy (Ph.D.) in Engineering, an Engineering Doctorate (Eng.D.), or an Engineer's degree. The Master and Engineer's degree may consist of either research, coursework or a mixture of the two. The Doctor of Philosophy and Engineering Doctorate degrees consist of a significant research component and are often viewed as the entry point to academia. In the United Kingdom and various other European countries, the Master of Engineering is often considered an undergraduate degree of slightly longer duration than the Bachelor of Engineering.[20]
[edit] Practicing engineers
In most countries, a Bachelor's degree in engineering represents the first step towards professional certification and the degree program itself is certified by a professional body. After completing a certified degree program the engineer must satisfy a range of requirements (including work experience requirements) before being certified. Once certified the engineer is designated the title of Professional Engineer (in the United States, Canada and South Africa ), Chartered Engineer (in India, Pakistan, the United Kingdom, Ireland and Zimbabwe), Chartered Professional Engineer (in Australia and New Zealand) or European Engineer (in much of the European Union).The advantages of certification vary depending upon location. For example, in the United States and Canada "only a licensed engineer may seal engineering work for public and private clients".[21] This requirement is enforced by state and provincial legislation such as Quebec's Engineers Act.[22] In other countries, no such legislation exists. Practically all certifying bodies maintain a code of ethics that they expect all members to abide by or risk expulsion.[23] In this way these organizations play an important role in maintaining ethical standards for the profession. Even in jurisdictions where certification has little or no legal bearing on work, engineers are subject to contract law. In cases where an engineer's work fails he or she may be subject to the tort of negligence and, in extreme cases, the charge of criminal negligence. An engineer's work must also comply with numerous other rules and regulations such as building codes and legislation pertaining to environmental law.
Professional bodies of note for electrical engineers include the Institute of Electrical and Electronics Engineers (IEEE) and the Institution of Engineering and Technology (IET). The IEEE claims to produce 30% of the world's literature in electrical engineering, has over 360,000 members worldwide and holds over 3,000 conferences annually.[24] The IET publishes 21 journals, has a worldwide membership of over 150,000, and claims to be the largest professional engineering society in Europe.[25][26] Obsolescence of technical skills is a serious concern for electrical engineers. Membership and participation in technical societies, regular reviews of periodicals in the field and a habit of continued learning are therefore essential to maintaining proficiency.[27]
In Australia, Canada and the United States electrical engineers make up around 0.25% of the labor force (see note). Outside of Europe and North America, engineering graduates per-capita, and hence probably electrical engineering graduates also, are most numerous in Taiwan, Japan, and South Korea.[28]
[edit] Tools and work
From the Global Positioning System to electric power generation, electrical engineers have contributed to the development of a wide range of technologies. They design, develop, test and supervise the deployment of electrical systems and electronic devices. For example, they may work on the design of telecommunication systems, the operation of electric power stations, the lighting and wiring of buildings, the design of household appliances or the electrical control of industrial machinery.[29]
Although most electrical engineers will understand basic circuit theory (that is the interactions of elements such as resistors, capacitors, diodes, transistors and inductors in a circuit), the theories employed by engineers generally depend upon the work they do. For example, quantum mechanics and solid state physics might be relevant to an engineer working on VLSI (the design of integrated circuits), but are largely irrelevant to engineers working with macroscopic electrical systems. Even circuit theory may not be relevant to a person designing telecommunication systems that use off-the-shelf components. Perhaps the most important technical skills for electrical engineers are reflected in university programs, which emphasize strong numerical skills, computer literacy and the ability to understand the technical language and concepts that relate to electrical engineering.
For many engineers, technical work accounts for only a fraction of the work they do. A lot of time may also be spent on tasks such as discussing proposals with clients, preparing budgets and determining project schedules.[30] Many senior engineers manage a team of technicians or other engineers and for this reason project management skills are important. Most engineering projects involve some form of documentation and strong written communication skills are therefore very important.
The workplaces of electrical engineers are just as varied as the types of work they do. Electrical engineers may be found in the pristine lab environment of a fabrication plant, the offices of a consulting firm or on site at a mine. During their working life, electrical engineers may find themselves supervising a wide range of individuals including scientists, electricians, computer programmers and other engineers.
[edit] Sub-disciplines
Electrical engineering has many sub-disciplines, the most popular of which are listed below. Although there are electrical engineers who focus exclusively on one of these sub-disciplines, many deal with a combination of them. Sometimes certain fields, such as electronic engineering and computer engineering, are considered separate disciplines in their own right.[edit] Power
Main article: Power engineering
Power engineering deals with the generation, transmission and distribution of electricity as well as the design of a range of related devices. These include transformers, electric generators, electric motors, high voltage engineering and power electronics. In many regions of the world, governments maintain an electrical network called a power grid that connects a variety of generators together with users of their energy. Users purchase electrical energy from the grid, avoiding the costly exercise of having to generate their own. Power engineers may work on the design and maintenance of the power grid as well as the power systems that connect to it. Such systems are called on-grid power systems and may supply the grid with additional power, draw power from the grid or do both. Power engineers may also work on systems that do not connect to the grid, called off-grid power systems, which in some cases are preferable to on-grid systems. The future includes Satellite controlled power systems, with feedback in real time to prevent power surges and prevent blackouts.
[edit] Control
Main article: Control engineering
Control engineers often utilize feedback when designing control systems. For example, in an automobile with cruise control the vehicle's speed is continuously monitored and fed back to the system which adjusts the motor's power output accordingly. Where there is regular feedback, control theory can be used to determine how the system responds to such feedback.
[edit] Electronics
Main article: Electronic engineering
Electronic engineering involves the design and testing of electronic circuits that use the properties of components such as resistors, capacitors, inductors, diodes and transistors to achieve a particular functionality. The tuned circuit, which allows the user of a radio to filter out all but a single station, is just one example of such a circuit. Another example (of a pneumatic signal conditioner) is shown in the adjacent photograph.
Prior to the second world war, the subject was commonly known as radio engineering and basically was restricted to aspects of communications and radar, commercial radio and early television. Later, in post war years, as consumer devices began to be developed, the field grew to include modern television, audio systems, computers and microprocessors. In the mid-to-late 1950s, the term radio engineering gradually gave way to the name electronic engineering.
Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by humans. These discrete circuits consumed much space and power and were limited in speed, although they are still common in some applications. By contrast, integrated circuits packed a large number—often millions—of tiny electrical components, mainly transistors, into a small chip around the size of a coin. This allowed for the powerful computers and other electronic devices we see today.
[edit] Microelectronics
Main article: Microelectronics
Microelectronics engineering deals with the design and microfabrication of very small electronic circuit components for use in an integrated circuit or sometimes for use on their own as a general electronic component. The most common microelectronic components are semiconductor transistors, although all main electronic components (resistors, capacitors, inductors) can be created at a microscopic level. Nanoelectronics is the further scaling of devices down to nanometer levels.
Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon (at higher frequencies, compound semiconductors like gallium arsenide and indium phosphide) to obtain the desired transport of electronic charge and control of current. The field of microelectronics involves a significant amount of chemistry and material science and requires the electronic engineer working in the field to have a very good working knowledge of the effects of quantum mechanics.
[edit] Signal processing
Main article: Signal processing
Signal Processing is a very mathematically oriented and intensive area forming the core of digital signal processing and it is rapidly expanding with new applications in every field of electrical engineering such as communications, control, radar, TV/Audio/Video engineering, power electronics and bio-medical engineering as many already existing analog systems are replaced with their digital counterparts.
Although in the classical era, analog signal processing only provided a mathematical description of a system to be designed, which is actually implemented by the analog hardware engineers, Digital Signal Processing both provides a mathematical description of the systems to be designed and also actually implements them (either by software programming or by hardware embedding) without much dependency on hardware issues, which exponentiates the importance and success of DSP engineering.
The deep and strong relations between signals and the information they carry makes signal processing equivalent of information processing. Which is the reason why the field finds so many diversified applications. DSP processor ICs are found in every type of modern electronic systems and products including, SDTV | HDTV sets, radios and mobile communication devices, Hi-Fi audio equipments, Dolby noise reduction algorithms, GSM mobile phones, mp3 multimedia players, camcorders and digital cameras, automobile control systems, noise cancelling headphones, digital spectrum analyzers, intelligent missile guidance, radar, GPS based cruise control systems and all kinds of image processing, video processing, audio processing and speech processing systems.
[edit] Telecommunications
Main article: Telecommunications engineering
Once the transmission characteristics of a system are determined, telecommunication engineers design the transmitters and receivers needed for such systems. These two are sometimes combined to form a two-way communication device known as a transceiver. A key consideration in the design of transmitters is their power consumption as this is closely related to their signal strength. If the signal strength of a transmitter is insufficient the signal's information will be corrupted by noise.
[edit] Instrumentation
Main article: Instrumentation engineering
Often instrumentation is not used by itself, but instead as the sensors of larger electrical systems. For example, a thermocouple might be used to help ensure a furnace's temperature remains constant. For this reason, instrumentation engineering is often viewed as the counterpart of control engineering.
[edit] Computers
Main article: Computer engineering
[edit] Related disciplines
Mechatronics is an engineering discipline which deals with the convergence of electrical and mechanical systems. Such combined systems are known as electromechanical systems and have widespread adoption. Examples include automated manufacturing systems, heating, ventilation and air-conditioning systems and various subsystems of aircraft and automobiles.The term mechatronics is typically used to refer to macroscopic systems but futurists have predicted the emergence of very small electromechanical devices. Already such small devices, known as Microelectromechanical systems (MEMS), are used in automobiles to tell airbags when to deploy, in digital projectors to create sharper images and in inkjet printers to create nozzles for high definition printing. In the future it is hoped the devices will help build tiny implantable medical devices and improve optical communication.[31]
Biomedical engineering is another related discipline, concerned with the design of medical equipment. This includes fixed equipment such as ventilators, MRI scanners and electrocardiograph monitors as well as mobile equipment such as cochlear implants, artificial pacemakers and artificial hearts.
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