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Electrical and Computer Engineering Commons™
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Full-Text Articles in Electrical and Computer Engineering
Transients In Power Systems, M. Belkhayat, J. Edwards, N. Hoonchareon, O. Marte, D. Stenberg, E. Walters
Transients In Power Systems, M. Belkhayat, J. Edwards, N. Hoonchareon, O. Marte, D. Stenberg, E. Walters
Department of Electrical and Computer Engineering Technical Reports
Power system engineering largely focuses on steady state analysis. The main areas of power system engineering are power flow studies and fault studies - both steady state technologies. But the world is largely transient, and power systems are always subject to time varying and short lived signals. This technical report concerns several important topics in transient analyses of power systems. The leading chapter deals with a new analytical tool-wavelets-for power system transients. Flicker and electric are furnace transients are discussed in Chapters I1 and IV. Chapter 111 deals with transients from shunt capacitor switching. The concluding chapters deal with transformer …
Differential Current Switch Logic: A Low Power Dcvs Logic Family, Dinesh Somasekhar, Kaushik Roy
Differential Current Switch Logic: A Low Power Dcvs Logic Family, Dinesh Somasekhar, Kaushik Roy
Department of Electrical and Computer Engineering Technical Reports
We present a new logic family, Differential Current Switch Logic (DCSL) for implementing clocked CMOS circuits. The circuit is in principle a differential cascode voltage switch logic circuit (DCVS). In cornparimsonto other forms of' clocked DCVS, DCSL achieves better performance both in terms of power and speed by restricting internal voltage swings in the N tree. Automatic lock-out of inputs on completion of evaluation is a novel feature of the circuit and allows new implementation of logic functions and the possibility of operating with reduced voltage swings. SPICE simulattions carried out with. the MOSIS 1 . 2 process indicate that …
Detecting Stator And Rotor Winding Faults In Three-Phase Induction Machines, Jeffrey C. Robertson, Chee Mun Ong
Detecting Stator And Rotor Winding Faults In Three-Phase Induction Machines, Jeffrey C. Robertson, Chee Mun Ong
Department of Electrical and Computer Engineering Technical Reports
The purpose of this work is to investigate the efficiency of existing methods for on-line fault detection when applied to three-phase induction motors, spc:cifically to test known theoretical calculations of harmonics developed by certain types of faults experimentally. The work involves the development of equipment and test procedures needed and research of existing methods of fault detection. The experiments are cor~ductedb y planting a fault in a test induction machine and then performing a Fast Fourier Transform (FFT) on the line current. The processed data are then compared with those from the same test machine before the fault was planted. …
Direction Of Arrival Estimation And Tracking Of Narrowband And Wideband Signals, A. Satish, Rangasami L. Kashyap
Direction Of Arrival Estimation And Tracking Of Narrowband And Wideband Signals, A. Satish, Rangasami L. Kashyap
Department of Electrical and Computer Engineering Technical Reports
The research addresses estimation and tracking of direction of arrival @OA) and associated parameters of narrowband and wideband signals impinging on a uniform linear array of sensors. The signals are modeled as sample functions of a Gaussian stochastic process. Computationally efficient, approximate maximum likelihood (ML) methods are developed for direction of arrival estimation of narrowband signals impinging on a large array of sensors. A new likelihood function is formulated based on a large M (# sensors) Taylor's series approximation of the original likelihood function. Asymptotic expressions for Cramer-Rao lower bounds on the DOA estimates are derived. From the positive definiteness …
On The Carrier Mobility In Forward-Biased Semiconductor Barriers, Mark S. Lundstrom, Shin'ichi Tanaka
On The Carrier Mobility In Forward-Biased Semiconductor Barriers, Mark S. Lundstrom, Shin'ichi Tanaka
Department of Electrical and Computer Engineering Faculty Publications
A simple one-speed solution to the Boltzmann equation is used to evaluate the mobility and diffusion coefficient for carriers in forward-biased semiconductor barriers. The analysis shows that although the average kinetic energy of carriers remains near thermal equilibrium, the mobility and diffusion coefficient are strongly reduced by the built-in field. Conventional macroscopic transport equations, which treat the carrier mobility and diffusion coefficient as single valued functions of the kinetic energy will improperly treat transport in forward-biased barriers. The results are important for the careful analysis of metal–semiconductor and heterojunction diodes.
On The Carrier Mobility In Forward-Biased Semiconductor Barriers, Mark S. Lundstrom, S. I. Tanaka
On The Carrier Mobility In Forward-Biased Semiconductor Barriers, Mark S. Lundstrom, S. I. Tanaka
Department of Electrical and Computer Engineering Faculty Publications
A simple one-speed solution to the Boltzmann equation is used to evaluate the mobility and diffusion coefficient for carriers in forward-biased semiconductor barriers. The analysis shows that although the average kinetic energy of carriers remains near thermal equilibrium, the mobility and diffusion coefficient are strongly reduced by the built-in field. Conventional macroscopic transport equations, which treat the carrier mobility and diffusion coefficient as single valued functions of the kinetic energy will improperly treat transport in forward-biased barriers. The results are important for the careful analysis of metal-semiconductor and heterojunction diodes.© 1995 American Institute of Physics.
Very Low Resistance Nonalloyed Ohmic Contacts Using Low-Temperature Molecular Beam Epitaxy Of Gaas, M. P. Patkar, T. P. Chin, J. M. Woodall, Mark S. Lundstrom, Michael R. Melloch
Very Low Resistance Nonalloyed Ohmic Contacts Using Low-Temperature Molecular Beam Epitaxy Of Gaas, M. P. Patkar, T. P. Chin, J. M. Woodall, Mark S. Lundstrom, Michael R. Melloch
Department of Electrical and Computer Engineering Faculty Publications
Ex situ nonalloyed ohmic contacts were made to n- and p‐type GaAs using low‐temperature molecular beam epitaxy. For n‐type GaAs, Ag, and Ti/Au nonalloyed contacts displayed specific contact resistitivities of mid 10-7 ohm cm2. For p‐type GaAs, nonalloyed Ti/Au contacts with specific contact resistivities of about 10-7 ohm cm2 were obtained.
Transition Matrix Approach For Monte Carlo Simulation Of Coupled Electron/Phonon/Photon Dynamics, Muhammad A. Alam, Mark S. Lundstrom
Transition Matrix Approach For Monte Carlo Simulation Of Coupled Electron/Phonon/Photon Dynamics, Muhammad A. Alam, Mark S. Lundstrom
Department of Electrical and Computer Engineering Faculty Publications
A new approach for simulating the dynamics of electrons, phonons, and photons is described. The technique provides a Monte Carlo simulation of particle dynamics without the statistical noise associated with direct Monte Carlo simulation, treats physical phenomena with a wide range of time scales, and has a good computational efficiency. A transition matrix is first precomputed by direct Monte Carlo simulation. Particle populations are then updated at regular time steps by simple matrix multiplication while correcting for nonlinear effects such as carrier–carrier scattering, band filling, hot phonons, etc. The technique is well suited to studies of quantum well laser devices …
Characterization Of Photon Recycling In Thin Crystalline Gaas Light Emitting Diodes, M. P. Patkar, M. S. Lundstrom, Michael R. Melloch
Characterization Of Photon Recycling In Thin Crystalline Gaas Light Emitting Diodes, M. P. Patkar, M. S. Lundstrom, Michael R. Melloch
Department of Electrical and Computer Engineering Faculty Publications
Gallium arsenide light emitting diodes (LEDs) were fabricated using molecular beam epitaxial films on GaAs substrates and removed by epitaxial lift-off (ELO). Lifted off devices were then mounted on a Si wafer using a Pd/Au/Cr contact layer, which also served as a back surface reflector. Devices were characterized by electrical and optical measurements, and the results for devices on the GaAs substrate were compared to those for EL0 devices. EL0 LEDs coated with a ZnS/MgF2 antireflection coating exhibited an optical output that was up to six times that of LEDs on GaAs substrates. At the same time, the measured current-voltage …
Temperature Dependence Of Minority And Majority Carrier Mobilities In Degenerately Doped Gaas, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom
Temperature Dependence Of Minority And Majority Carrier Mobilities In Degenerately Doped Gaas, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom
Department of Electrical and Computer Engineering Faculty Publications
Measured minority and majority carrier mobility temperature dependencies in heavily doped n- and p-GaAs are compared. Majority carrier mobilities in heavily doped GaAs are essentially temperature ~T! independent while minority carrier mobilities exhibit a roughly 1/T dependence. Majority carrier freezeout, which reduces both majority–minority carrier and ionized impurity scattering, is shown not to be responsible for the 1/T minority carrier mobility dependence. The difference in minority and majority carrier mobility T dependencies is explained in terms of the increased degree of degeneracy of majority carriers with decreased temperature, which decreases majority–minority carrier scattering.