Atnaujinkite slapukų nuostatas

Electric Energy: An Introduction, Third Edition 3rd edition [Kietas viršelis]

3.74/5 (32 ratings by Goodreads)
(University of Washington, Seattle, USA)
  • Formatas: Hardback, 606 pages, aukštis x plotis: 254x178 mm, weight: 1400 g, 17 Tables, black and white; 530 Illustrations, black and white
  • Serija: Power Electronics and Applications Series
  • Išleidimo metai: 08-Nov-2012
  • Leidėjas: CRC Press Inc
  • ISBN-10: 1466503033
  • ISBN-13: 9781466503038
Kitos knygos pagal šią temą:
Electric Energy: An Introduction, Third Edition 3rd editionDidesnis paveikslėlis
  • Formatas: Hardback, 606 pages, aukštis x plotis: 254x178 mm, weight: 1400 g, 17 Tables, black and white; 530 Illustrations, black and white
  • Serija: Power Electronics and Applications Series
  • Išleidimo metai: 08-Nov-2012
  • Leidėjas: CRC Press Inc
  • ISBN-10: 1466503033
  • ISBN-13: 9781466503038
Kitos knygos pagal šią temą:
Kitos knygos iš šio išskirtinio pasiūlymo: Taylor & Francis siūlo daug technologijos knygų ISE (International Student Edition) kainomis
Pastovi nuoroda: https://www.kriso.lt/db/9781466503038.html
Raktažodžiai:
The search for renewable energy and smart grids, the societal impact of blackouts, and the environmental impact of generating electricity, along with the new ABET criteria, continue to drive a renewed interest in electric energy as a core subject. Keeping pace with these changes, Electric Energy: An Introduction, Third Edition restructures the traditional introductory electric energy course to better meet the needs of electrical and mechanical engineering students.

Now in color, this third edition of a bestselling textbook gives students a wider view of electric energy, without sacrificing depth. Coverage includes energy resources, renewable energy, power plants and their environmental impacts, electric safety, power quality, power market, blackouts, and future power systems. The book also makes the traditional topics of electromechanical conversion, transformers, power electronics, and three-phase systems more relevant to students. Throughout, it emphasizes issues that engineers encounter in their daily work, with numerous examples drawn from real systems and real data.

Whats New in This Edition





Color illustrations Substation and distribution equipment Updated data on energy resources Expanded coverage of power plants Expanded material on renewable energy Expanded material on electric safety Three-phase system and pulse width modulation for DC/AC converters Induction generator More information on smart grids Additional problems and solutions

Combining the fundamentals of traditional energy conversion with contemporary topics in electric energy, this accessible textbook gives students the broad background they need to meet future challenges.

Recenzijos

"El-Sharkawis book is an excellent introduction to electric power. ... This very well-written book describes the hardware used in electrical power generation and transmission. Particularly valuable are the color pictures showing power plants, transmission lines and other hardware. The operation principles of the system are also clearly described in the book, without complicated unnecessary details. These explanations give an appropriate picture of the power system operation for incoming students. ... Particularly important are the clear discussion of renewable energy generation and the explanation of emerging generation techniques like fuel cells. The book presents well-prepared, practical numerical examples, which enforce students ability to solve engineering problems." George G. Karady, Arizona State University, Tempe, USA

"This is a great piece of work. It combines a diverse set of materials creatively in a single text. Excellent!" Peter Idowu, Penn State Harrisburg, Middletown, USA

"The strength of this book is in its broad treatment of electric energy components and systems in a way that is both useful to engineering students as a stand-alone course, and provides background for more advanced study in these topics." Paul Hines, The University of Vermont, Burlington, USA

Praise for the Second Edition

"I found the book to be a nice introductory course to the discipline of electric energy production, transmission, and distribution. I would recommend it to the undergraduate student beginning to explore the rewarding career path of electrical engineering, and equally so to nontechnical professionals working in the power and energy industry who may wish to gain greater insight into the functioning and operations of the electric power system. I truly enjoyed reading this book." Pouyan Pourbeik, IEEE Power & Energy Magazine "El-Sharkawis book is an excellent introduction to electric power. ... This very well-written book describes the hardware used in electrical power generation and transmission. Particularly valuable are the color pictures showing power plants, transmission lines and other hardware. The operation principles of the system are also clearly described in the book, without complicated unnecessary details. These explanations give an appropriate picture of the power system operation for incoming students. ... Particularly important are the clear discussion of renewable energy generation and the explanation of emerging generation techniques like fuel cells. The book presents well-prepared, practical numerical examples, which enforce students ability to solve engineering problems." George G. Karady, Arizona State University, Tempe, USA

"This is a great piece of work. It combines a diverse set of materials creatively in a single text. Excellent!"Peter Idowu, Penn State Harrisburg, Middletown, USA

"The strength of this book is in its broad treatment of electric energy components and systems in a way that is both useful to engineering students as a stand-alone course, and provides background for more advanced study in these topics."Paul Hines, The University of Vermont, Burlington, USA

Praise for the Second Edition

"I found the book to be a nice introductory course to the discipline of electric energy production, transmission, and distribution. I would recommend it to the undergraduate student beginning to explore the rewarding career path of electrical engineering, and equally so to nontechnical professionals working in the power and energy industry who may wish to gain greater insight into the functioning and operations of the electric power system. I truly enjoyed reading this book."Pouyan Pourbeik, IEEE Power & Energy Magazine

Preface xv
Author xix
List of Acronyms
xxi
Chapter 1 History of Power Systems
1(16)
1.1 Thomas A. Edison (1847-1931)
5(2)
1.2 Nikola Tesla (1856-1943)
7(1)
1.3 Battle of AC versus DC
8(5)
1.4 Today's Power Systems
13(1)
Exercises
14(3)
Chapter 2 Basic Components of Power Systems
17(24)
2.1 Power Plants
17(3)
2.1.1 Turbines
18(2)
2.1.2 Generators
20(1)
2.2 Transformers
20(1)
2.3 Transmission Lines
20(2)
2.4 Distribution Lines
22(1)
2.5 Conductors
23(3)
2.5.1 Bundled Conductor
24(2)
2.5.2 Static (Shield) Wire
26(1)
2.6 Substations
26(9)
2.6.1 Potential Transformer
28(1)
2.6.2 Current Transformer
29(2)
2.6.3 Circuit Breaker
31(2)
2.6.4 Disconnecting Switches
33(1)
2.6.5 Surge Arrester
34(1)
2.7 Control Centers
35(2)
2.8 Worldwide Standards for Household Voltage and Frequency
37(2)
2.8.1 Voltage Standard
38(1)
2.8.2 Frequency Standard
38(1)
2.8.2.1 Frequency of Generating Plants
38(1)
2.8.2.2 Frequency of Power Grids
39(1)
Exercises
39(2)
Chapter 3 Energy Resources
41(12)
3.1 Fossil Fuel
44(6)
3.1.1 Oil
45(2)
3.1.2 Natural Gas
47(1)
3.1.3 Coal
48(2)
3.2 Nuclear Fuel
50(1)
Exercises
51(2)
Chapter 4 Power Plants
53(36)
4.1 Hydroelectric Power Plants
53(17)
4.1.1 Types of Hydroelectric Power Plants
53(2)
4.1.2 Impoundment Hydroelectric Power Plants
55(2)
4.1.2.1 Impulse Turbine
57(5)
4.1.2.2 Reaction Turbine
62(3)
4.1.2.3 Reservoir
65(1)
4.1.2.4 Penstock
66(2)
4.1.2.5 Power Flow
68(2)
4.2 Fossil Fuel Power Plants
70(5)
4.2.1 Thermal Energy Constant
71(1)
4.2.2 Description of Thermal Power Plant
72(3)
4.3 Nuclear Power Plants
75(11)
4.3.1 Nuclear Fuel
75(1)
4.3.2 Uranium Enrichment
76(1)
4.3.3 Fission Process
76(4)
4.3.4 Fission Control
80(1)
4.3.5 Boiling Water Reactor
81(1)
4.3.6 Pressurized Water Reactor
82(1)
4.3.7 CANDU Reactor
82(2)
4.3.8 Safety Features in Nuclear Power Plants
84(1)
4.3.9 Disposal of Nuclear Waste
85(1)
4.3.9.1 Wet Storage
85(1)
4.3.9.2 Dry Storage
85(1)
4.3.9.3 Permanent Storage
85(1)
Exercises
86(3)
Chapter 5 Environmental Impact of Power Plants
89(10)
5.1 Environmental Concerns Related to Fossil Fuel Power Plants
90(6)
5.1.1 Sulfur Oxides
90(2)
5.1.2 Nitrogen Oxides
92(1)
5.1.3 Ozone
92(1)
5.1.4 Acid Rain
93(1)
5.1.5 Carbon Dioxide
94(1)
5.1.6 Ashes
95(1)
5.1.7 Legionnaires' Disease and Cooling Towers
95(1)
5.2 Environmental Concerns Related to Hydroelectric Power Plants
96(1)
5.2.1 Case Study: The Aswan Dam
96(1)
5.3 Environmental Concerns Related to Nuclear Power Plants
97(1)
5.3.1 Radioactive Release During Normal Operation
97(1)
5.3.2 Loss of Coolant
97(1)
5.3.3 Disposal of Radioactive Waste
98(1)
Exercises
98(1)
Chapter 6 Renewable Energy
99(114)
6.1 Solar Energy
99(34)
6.1.1 Passive Solar Energy System
103(1)
6.1.2 Active Solar Energy System (Photovoltaic)
104(4)
6.1.2.1 Ideal PV Model
108(9)
6.1.2.2 Effect of Irradiance and Temperature on Solar Cells
117(2)
6.1.2.3 PV Module
119(5)
6.1.2.4 Real Model of PV
124(3)
6.1.2.5 Daily Power Profile of PV Array
127(1)
6.1.2.6 Photovoltaic System Integration
128(3)
6.1.2.7 Evaluation of PV Systems
131(2)
6.2 Wind Energy
133(25)
6.2.1 Kinetic Energy of Wind
133(3)
6.2.2 Wind Turbine
136(1)
6.2.3 Aerodynamic Force
137(2)
6.2.4 Angle-of-Attack
139(2)
6.2.5 Pitch Angle
141(1)
6.2.6 Coefficient of Performance and Turbine Efficiency
142(1)
6.2.7 Operating Range of Wind Turbine
143(1)
6.2.8 Tip Speed Ratio
143(4)
6.2.9 Feathering
147(1)
6.2.10 Classifications of Wind Turbines
147(1)
6.2.10.1 Alignment of Rotating Axis
147(2)
6.2.10.2 Types of Generators
149(1)
6.2.10.3 Speed of Rotation
150(1)
6.2.11 Types of Wind Turbine
150(1)
6.2.11.1 Type 1 Wind Turbine
151(1)
6.2.11.2 Type 2 Wind Turbine
151(1)
6.2.11.3 Type 3 Wind Turbine
152(1)
6.2.11.4 Type 4 Wind Turbine
152(1)
6.2.12 Wind Farm Performance
153(1)
6.2.13 Evaluation of Wind Energy
154(4)
6.3 Hydrokinetic Systems
158(20)
6.3.1 Small Hydro Systems
158(1)
6.3.1.1 Main Components of Small Hydro System
158(2)
6.3.1.2 Effective Head
160(2)
6.3.1.3 System Efficiency
162(1)
6.3.1.4 Site Calculations
163(2)
6.3.1.5 Evaluation of Small Hydro Systems
165(1)
6.3.2 Tidal and Stream Energy System
165(1)
6.3.2.1 Barrage System
165(4)
6.3.2.2 Water Stream Energy
169(3)
6.3.2.3 Evaluation of Tidal and Stream Energy
172(1)
6.3.3 Wave Energy System
173(1)
6.3.3.1 Buoyant Moored System
174(1)
6.3.3.2 Hinged Contour System
175(1)
6.3.3.3 Oscillating Water Column System
176(2)
6.3.3.4 Evaluation of Wave Energy
178(1)
6.4 Geothermal Energy
178(8)
6.4.1 Heat Pump
181(1)
6.4.2 Geothermal Electricity
181(1)
6.4.2.1 Geothermal Reservoir
181(1)
6.4.2.2 Hot Dry Rock
182(1)
6.4.3 Geothermal Power Plants
182(3)
6.4.3.1 Evaluation of Geothermal Energy
185(1)
6.5 Biomass Energy
186(1)
6.6 Fuel Cell
187(16)
6.6.1 Hydrogen Fuel
188(1)
6.6.2 Types of Fuel Cells
189(1)
6.6.2.1 Proton Exchange Membrane Fuel Cell
189(2)
6.6.2.2 Alkaline Fuel Cell
191(1)
6.6.2.3 Phosphoric Acid Fuel Cell
192(1)
6.6.2.4 Solid Oxide Fuel Cell
193(1)
6.6.2.5 Molten Carbonate Fuel Cell
193(1)
6.6.2.6 Direct Methanol Fuel Cell
194(1)
6.6.3 Hydrogen Economy
195(2)
6.6.4 Modeling of Ideal Fuel Cells
197(1)
6.6.4.1 Thermal Process of Fuel Cells
197(1)
6.6.4.2 Electrical Process of Fuel Cells
198(1)
6.6.5 Modeling of Actual Fuel Cells
199(1)
6.6.5.1 Polarization Characteristics of Fuel Cells
199(2)
6.6.6 Evaluation of Fuel Cells
201(1)
6.6.7 Fuel Cells and the Environment
202(1)
6.6.7.1 Generation of Hydrogen
202(1)
6.6.7.2 Safety of Hydrogen
202(1)
6.7 Intermittency of Renewable Systems
203(1)
6.8 Energy Storage Systems
204(5)
6.8.1 Pumped Hydro Storage
204(1)
6.8.2 Compressed Air Energy Storage
205(2)
6.8.3 Batteries
207(1)
6.8.4 Flywheels
208(1)
Exercises
209(4)
Chapter 7 Alternating Current Circuits
213(34)
7.1 Alternating Current Waveform
213(1)
7.2 Root Mean Square
214(2)
7.3 Phase Shift
216(2)
7.4 Concept of Phasors
218(1)
7.5 Complex Number Analysis
219(3)
7.6 Complex Impedance
222(5)
7.6.1 Series Impedance
223(2)
7.6.2 Parallel Impedance
225(2)
7.7 Electric Power
227(15)
7.7.1 Real Power
230(1)
7.7.2 Reactive Power
230(1)
7.7.3 Complex Power
231(1)
7.7.4 Summary of AC Phasors
232(1)
7.7.5 Power Factor
233(1)
7.7.6 Problems Related to Reactive Power
233(5)
7.7.7 Power Factor Correction
238(4)
7.8 Electric Energy
242(2)
Exercises
244(3)
Chapter 8 Three-Phase Systems
247(26)
8.1 Generation of Three-Phase Voltages
247(3)
8.2 Connections of Three-Phase Circuits
250(18)
8.2.1 Wye-Connected Balanced Source
251(4)
8.2.2 Delta-Connected Balanced Source
255(1)
8.2.3 Wye-Connected Balanced Load
256(3)
8.2.4 Delta-Connected Balanced Load
259(3)
8.2.5 Circuits with Mixed Connections
262(3)
8.2.6 Wye-Delta Transformation
265(3)
8.3 Power Calculations of Balanced Three-Phase Circuits
268(3)
8.3.1 Three-Phase Power of Balanced Wye Loads
269(1)
8.3.2 Three-Phase Power of Balanced Delta Loads
269(2)
Exercises
271(2)
Chapter 9 Electric Safety
273(44)
9.1 Electric Shock
273(7)
9.1.1 Current Limits of Electric Shocks
274(1)
9.1.2 Factors Determining the Severity of Electric Shocks
275(1)
9.1.2.1 Effect of Voltage
275(1)
9.1.2.2 Effect of Current
276(1)
9.1.2.3 Effect of Body Resistance
276(1)
9.1.2.4 Effect of Current Pathway
277(1)
9.1.2.5 Effect of Shock Duration
277(1)
9.1.2.6 Effect of Frequency
277(1)
9.1.2.7 Effect of Ground Resistance
278(2)
9.2 Ground Resistance
280(6)
9.2.1 Ground Resistance of Objects
280(4)
9.2.2 Measuring Ground Resistance of Objects
284(1)
9.2.3 Ground Resistance of People
284(2)
9.3 Touch and Step Potentials
286(7)
9.3.1 Touch Potential
286(4)
9.3.2 Step Potential
290(3)
9.4 Electric Safety at Home
293(17)
9.4.1 Neutral versus Ground
294(1)
9.4.1.1 Grounding Chassis
295(2)
9.4.1.2 Bonding Chassis to Neutral
297(2)
9.4.1.3 Grounding Chassis and Bonding Ground to Neutral
299(3)
9.4.2 Dwelling Distribution Circuits
302(2)
9.4.3 Ground Fault Circuit Interrupter
304(2)
9.4.4 Neutral Integrity
306(3)
9.4.5 World's Residential Grounding Practices
309(1)
9.5 Low Frequency Magnetic Field and Its Health Effects
310(4)
9.5.1 Low-Frequency Magnetic Fields
311(1)
9.5.2 Biological Effects of Magnetic Field
312(1)
9.5.3 Standards for Magnetic Field
313(1)
Exercises
314(3)
Chapter 10 Power Electronics
317(46)
10.1 Power Electronic Devices
318(10)
10.1.1 Solid-State Diodes
318(1)
10.1.2 Transistors
319(1)
10.1.2.1 Bipolar Junction Transistor
320(4)
10.1.2.2 Metal Oxide Semiconductor Field Effect Transistor
324(1)
10.1.3 Thyristors
325(1)
10.1.3.1 Silicon-Controlled Rectifier
325(1)
10.1.3.2 Silicon Diode for Alternating Current
326(1)
10.1.4 Hybrid Power Electronic Devices
327(1)
10.1.4.1 Darlington Transistor
327(1)
10.1.4.2 Insulated Gate Bipolar Transistor
328(1)
10.2 Solid-State Switching Circuits
328(32)
10.2.1 AC/DC Converters
328(2)
10.2.1.1 Rectifier Circuits
330(3)
10.2.1.2 Voltage-Controlled Circuits
333(3)
10.2.1.3 Constant-Current Circuits
336(3)
10.2.1.4 Three-Phase Circuits
339(5)
10.2.2 DC/DC Converters
344(1)
10.2.2.1 Buck Converter
344(1)
10.2.2.2 Boost Converter
345(3)
10.2.2.3 Buck-Boost Converter
348(3)
10.2.3 DC/AC Converters
351(1)
10.2.3.1 Single-Phase DC/AC Converter
351(1)
10.2.3.2 Three-Phase DC/AC Converter
352(4)
10.2.3.3 Pulse Width Modulation
356(2)
10.2.4 AC/AC Converters
358(2)
Exercises
360(3)
Chapter 11 Transformers
363(32)
11.1 Theory of Operation
363(7)
11.1.1 Voltage Ratio
365(2)
11.1.2 Current Ratio
367(1)
11.1.3 Reflected Load Impedance
367(2)
11.1.4 Transformer Ratings
369(1)
11.2 Multi-Winding Transformer
370(2)
11.3 Autotransformer
372(3)
11.4 Three-Phase Transformer
375(8)
11.4.1 Three-Phase Transformer Ratings
375(1)
11.4.1.1 Wye-Wye Transformer
376(2)
11.4.1.2 Delta-Delta Transformer
378(2)
11.4.1.3 Wye-Delta Transformer
380(2)
11.4.2 Transformer Bank
382(1)
11.5 Actual Transformer
383(9)
11.5.1 Analysis of Actual Transformer
386(4)
11.5.2 Transformer Efficiency
390(1)
11.5.3 Voltage Regulation
391(1)
Exercises
392(3)
Chapter 12 Electric Machines
395(86)
12.1 Rotating Magnetic Field
395(4)
12.2 Rotating Induction Motor
399(20)
12.2.1 Rotation of Induction Motor
401(2)
12.2.2 Equivalent Circuit of Induction Motor
403(4)
12.2.3 Power Analysis
407(3)
12.2.4 Speed-Torque Relationship
410(3)
12.2.5 Starting Torque and Starting Current
413(1)
12.2.6 Maximum Torque
414(1)
12.2.7 Starting Methods
415(1)
12.2.7.1 Voltage Reduction
416(1)
12.2.7.2 Insertion of Resistance
417(2)
12.3 Linear Induction Motor
419(8)
12.3.1 Wheeled Linear Induction Motor
420(6)
12.3.2 Magnetically Levitated Induction Motor
426(1)
12.4 Induction Generator
427(5)
12.5 Synchronous Generator
432(19)
12.5.1 Synchronous Generator Connected to Infinite Bus
439(1)
12.5.1.1 Power of Synchronous Generator
440(4)
12.5.2 Synchronous Generator Connected to Infinite Bus through a Transmission Line
444(4)
12.5.3 Increase Transmission Capacity
448(1)
12.5.3.1 Increasing Transmission Capacity by Using Series Capacitor
448(1)
12.5.3.2 Increasing Transmission Capacity by Using Parallel Lines
449(2)
12.6 Synchronous Motor
451(6)
12.6.1 Power of Synchronous Motor
454(1)
12.6.2 Reactive Power Control and Synchronous Condenser
454(2)
12.6.3 Motor Torque
456(1)
12.7 Direct Current Motor
457(7)
12.7.1 Theory of Operation of DC Motor
459(2)
12.7.2 Starting of DC Motor
461(1)
12.7.3 Speed Control of DC Motor
462(2)
12.8 Stepper Motor
464(8)
12.8.1 Variable Reluctance Stepper Motor
465(2)
12.8.2 Permanent Magnet Stepper Motor
467(1)
12.8.3 Hybrid Stepper Motor
468(1)
12.8.4 Holding State of Stepper Motor
468(3)
12.8.5 Rotating Stepper Motor
471(1)
12.9 Single-Phase Motors
472(4)
12.9.1 Split-Phase Motors
472(3)
12.9.2 Capacitor Starting Motors
475(1)
12.9.3 Shaded-Pole Motors
476(1)
Exercises
476(5)
Chapter 13 Power Quality
481(34)
13.1 Voltage Problems
481(15)
13.1.1 Voltage Flickers
484(4)
13.1.2 Voltage Sag
488(8)
13.2 Harmonic Problems
496(16)
13.2.1 Harmonic Distortion of Electric Loads
499(5)
13.2.2 Resonance due to Harmonics
504(3)
13.2.3 Effect of Harmonics on Transmission Lines and Cables
507(1)
13.2.4 Effect of Harmonics on Capacitor Banks
507(1)
13.2.5 Effect of Harmonics on Electric Machines
508(1)
13.2.6 Effect of Harmonics on Electric Power
509(3)
13.2.7 Effect of Harmonics on Communications
512(1)
Exercises
512(3)
Chapter 14 Power Grid and Blackouts
515(26)
14.1 Topology of Power Systems
517(2)
14.1.1 Enhancing Power System Reliability by Adding Transmission Lines
518(1)
14.1.2 Enhancing Power System Reliability by Adding Generation
518(1)
14.2 Analysis of Power Networks
519(4)
14.3 Electric Energy Demand
523(3)
14.4 Trading Electric Energy
526(2)
14.5 World Wide Web of Power
528(1)
14.6 Anatomy of Blackouts
529(7)
14.6.1 Balance of Electric Power
530(1)
14.6.2 Balance of Electrical and Mechanical Powers
531(3)
14.6.2.1 Control Actions for Decreased Demand
534(1)
14.6.2.2 Control Actions for Increased Demand
534(2)
14.7 Blackout Scenarios
536(3)
14.7.1 Great Northeast Blackout of 1965
537(1)
14.7.2 Great Blackout of 1977
537(1)
14.7.3 Great Blackout of 2003
538(1)
Exercises
539(2)
Chapter 15 Future Power Systems
541(18)
15.1 Smart Grid
541(9)
15.1.1 Intelligent Monitoring
545(3)
15.1.2 Smart House
548(1)
15.1.3 Self-Diagnosis and Self-Healing
549(1)
15.2 Electric and Hybrid Electric Vehicles
550(3)
15.3 Alternative Resources
553(1)
15.4 Less Polluting Power Plants
553(1)
15.5 Distributed Generation
554(1)
15.6 Power Electronics
554(1)
15.7 Enhanced Reliability
555(1)
15.8 Intelligent Operation, Maintenance, and Training
555(1)
15.9 Space Power Plants
555(2)
Exercises
557(2)
Appendix A Units and Symbols 559(2)
Appendix B Conversions 561(2)
Appendix C Key Parameters 563(2)
Appendix D Inductors 565(2)
Appendix E Key Integrals 567(2)
Index 569
Mohamed A. El-Sharkawi is a fellow of the IEEE and a professor of electrical engineering in the energy area at the University of Washington. He has published more than 250 papers and holds five licensed patents in the area of renewable energy VAR management and minimum arc sequential circuit breaker switching. For more information, please visit Professor El-Sharkawis website at the University of Washington.