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Articles 3691 - 3720 of 3959

Full-Text Articles in Physical Sciences and Mathematics

Phonon Replicas In The Photoluminescence Emission Of Alxga1-Xas Alloys, D. C. Reynolds, David C. Look, R. Kaspi, D. N. Talwar Jun 1995

Phonon Replicas In The Photoluminescence Emission Of Alxga1-Xas Alloys, D. C. Reynolds, David C. Look, R. Kaspi, D. N. Talwar

Physics Faculty Publications

Phonon replicas in the photoluminescence spectra of a direct gap AlxGa1−xAs alloy have been observed. The GaAs‐like transverse optical and longitudinal optical as well as AlAs‐like longitudinal optical modes were observed at the Γ‐point. We also observe what we believe to be the longitudinal acoustical phonons at the L‐point in the Brillouin zone.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 5, May 1995, College Of Engineering And Computer Science, Wright State University May 1995

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 5, May 1995, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Electrical Field Enhanced Thermal Quenching Of A Prominent Thermally Stimulated Current Peak In Semi-Insulating Gaas, Z-Q. Fang, David C. Look May 1995

Electrical Field Enhanced Thermal Quenching Of A Prominent Thermally Stimulated Current Peak In Semi-Insulating Gaas, Z-Q. Fang, David C. Look

Physics Faculty Publications

Detailed experimental results are presented for a ‘‘thermal quenching’’ of thermal stimulated current signals in the most prominent trap in undoped semi‐insulating (SI) GaAs, T5 with an activation energy of 0.27–0.31 eV. A possible model for the thermal quenching of T5 is discussed, emphasizing the thermally stimulated nature of the quenching process, the effect of electric field and the formation of high‐field domains. The thermal quenching of T5 can frequency be observed in SI GaAs grown by the vertical gradient freeze (VGF) technique, or by the liquid encapsulated Czochralski (LEC) technique under certain conditions.

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A Meta-Interpreter For Circuit-Extraction, Krishnaprasad Thirunarayan May 1995

A Meta-Interpreter For Circuit-Extraction, Krishnaprasad Thirunarayan

Kno.e.sis Publications

The design of a VLSI circuit consists of a description of the circuit in terms of its components and subcomponents, at various levels of detail. To verify that the layout of a VLSI circuit conforms to its design, one needs to work backwards from the lowest-level description of the circuit and recognize the higher-level components it constitutes. This paper is concerned with the application of logic programming techniques in the formal verification of the structural correctness of the VLSI circuit layouts. In particular, we review Michael Dukes' Generalized Extraction System (1990) that compiles design descriptions into a set of extraction …

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Free-Boundary Problems For Potential And Stokes Flows Via Nonsmooth Analysis, Srdjan Stojanovic, Tom Svobodny May 1995

Free-Boundary Problems For Potential And Stokes Flows Via Nonsmooth Analysis, Srdjan Stojanovic, Tom Svobodny

Mathematics and Statistics Faculty Publications

A new approach to some free boundary problems of the type of jets and cavities for potential flows is introduced. Both potential and Stokes flows are considered. The variable domain problems are relaxed so that they become nonsmooth optimization problems on fixed domains for somewhat singular state equations. State equations are considered, and multivalued generalized gradients of the variational functionals are studied. The method is constructive.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 4, April 1995, College Of Engineering And Computer Science, Wright State University Apr 1995

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 4, April 1995, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A twelve page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 3, March 1995, College Of Engineering And Computer Science, Wright State University Mar 1995

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 3, March 1995, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Principal Points And Self-Consistent Points Of Elliptical Distributions, Thaddeus Tarpey, Luning Li, Bernard Flury Feb 1995

Principal Points And Self-Consistent Points Of Elliptical Distributions, Thaddeus Tarpey, Luning Li, Bernard Flury

Mathematics and Statistics Faculty Publications

In this paper we study principal points and self-consistent points of p-variate elliptical distributions. We also discuss implications of our results for the computation and estimation of principal points.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 2, February 1995, College Of Engineering And Computer Science, Wright State University Feb 1995

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 2, February 1995, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

An eighteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Convenient Determination Of Concentration And Energy In Deep-Level Transient Spectroscopy, David C. Look, Z-Q. Fang, J. R. Sizelove Feb 1995

Convenient Determination Of Concentration And Energy In Deep-Level Transient Spectroscopy, David C. Look, Z-Q. Fang, J. R. Sizelove

Physics Faculty Publications

For defects or impurities with deep energy levels, such as the commonly observed EL2, EL3, and EL6 in GaAs, it is very important to take account of the so‐called λ effect in order to deduce the correct concentrations of these centers when using capacitance techniques. By measuring capacitance at several forward bias voltages for a given reverse bias voltage it is possible to determine concentration NT and energy ET without requiring the usual emission rate analysis. Convenient formulas for NT and ET are given, although only NT can be determined with a high degree of …

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 1, January 1995, College Of Engineering And Computer Science, Wright State University Jan 1995

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 11, Number 1, January 1995, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Nonrecursive Incremental Evaluation Of Datalog Queries, Guozhu Dong, Jianwen Su, Rodney Topor Jan 1995

Nonrecursive Incremental Evaluation Of Datalog Queries, Guozhu Dong, Jianwen Su, Rodney Topor

Kno.e.sis Publications

We consider the problem of repeatedly evaluating the same (computationally expensive) query to a database that is being updated between successive query requests. In this situation, it should be possible to use the difference between successive database states and the answer to the query in one state to reduce the cost of evaluating the query in the next state. We use nonrecursive Datalog (which are unions of conjunctive queries) to compute the differences, and call this process “incremental query evaluation using conjunctive queries”. After formalizing the notion of incremental query evaluation using conjunctive queries, we give an algorithm that constructs, …

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Monte-Carlo Simulation Of Bulk Hole Transport In Alxga1-Xas, In1-Xalxas, And Gaasxsb1-X, M. J. Martinez, David C. Look, J. R. Sizelove, F. L. Schuermeyer Jan 1995

Monte-Carlo Simulation Of Bulk Hole Transport In Alxga1-Xas, In1-Xalxas, And Gaasxsb1-X, M. J. Martinez, David C. Look, J. R. Sizelove, F. L. Schuermeyer

Physics Faculty Publications

We report a Monte Carlo study of hole transport in AlxGa1−xAs, In1−xAlxAs, and GaAsxSb1−x. The effects of alloy scattering are significant in all three cases, but mobilities are still high enough to be advantageous in particular device applications. We separately calculate the Hall r factors by a Boltzmann transport method and show that these factors are vitally important when attempting to compare Monte Carlo drift mobilities with experimental Hall data.

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A Theoretical Study Concerning The Solar Cycle Dependence Of The Nightside Ionosphere Of Venus, Zoltan Dobe, Andrew F. Nagy, Jane L. Fox Jan 1995

A Theoretical Study Concerning The Solar Cycle Dependence Of The Nightside Ionosphere Of Venus, Zoltan Dobe, Andrew F. Nagy, Jane L. Fox

Physics Faculty Publications

We modeled the chemical and physical processes taking place in the nightside ionosphere of Venus by solving the one dimensional coupled continuity and momentum equations for 12 ion species [CO2+, O2+, O+, H+, NO+, CO+, N2+, N+, He+, C+, O+ (²D) and O+ (²P)]. We investigated the relative importance of the two major processes responsible for maintaining the nightside plasma densities: atomic ion transport from the dayside and impact ionization due to energetic electron precipitation. …

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Demonstration Of Semiconductor Characterization By Phonon Side-Band In Photoluminescence, D. C. Reynolds, David C. Look, D. N. Talwar, G. L. Mccoy, K. R. Evans Jan 1995

Demonstration Of Semiconductor Characterization By Phonon Side-Band In Photoluminescence, D. C. Reynolds, David C. Look, D. N. Talwar, G. L. Mccoy, K. R. Evans

Physics Faculty Publications

In this paper two GaAs samples were investigated; one was a very pure sample grown by chemical-vapor deposition, the other was grown by molecular-beam epitaxy. The dominant optical transition in the high-purity sample was the donor-bound-exciton transition. Phonon sidebands associated with both the free exciton and the donor-bound exciton were observed. The active phonons were the longitudinal-optical (LO) and the transverse-optical (TO) modes associated with both the free exciton and the donor-bound exciton at the Γ point in k space; the TO mode from the donor-bound exciton at the X point, the LO from the free exciton at the L …

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Singularity Of Super-Brownian Local Time At A Point Catalyst, Donald A. Dawson, Klaus Fleischmann, Yi Li, Carl Mueller Jan 1995

Singularity Of Super-Brownian Local Time At A Point Catalyst, Donald A. Dawson, Klaus Fleischmann, Yi Li, Carl Mueller

Mathematics and Statistics Faculty Publications

No abstract provided.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 10, December 1994, College Of Engineering And Computer Science, Wright State University Dec 1994

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 10, December 1994, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 9, November 1994, College Of Engineering And Computer Science, Wright State University Nov 1994

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 9, November 1994, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A fourteen page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Interaction Of A Group Of Dislocations Within The Framework Of The Continuum Frenkel-Kontorova Model, Naum I. Gershenzon Nov 1994

Interaction Of A Group Of Dislocations Within The Framework Of The Continuum Frenkel-Kontorova Model, Naum I. Gershenzon

Physics Faculty Publications

The Frenkel-Kontorova (FK) model of edge dislocation is analyzed. Solutions of the continuum limit of the FK model [the sine-Gordon (SG) equation] are obtained in a form convenient for investigation of dynamics of a large number of interacting dislocations. We consider, based on these solutions, some nonstationary processes: dislocation generation, diffusion of dislocations, and crack-dislocation interaction. Simple relations connecting the velocity of plastic deformation, density and velocity of dislocations, and the force of interaction between dislocations are obtained. The nucleation of dislocations at a moving crack tip is described.

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The "Infoharness" Information Integration Platform, Leon Shklar, Satish Thatte, Howard Marcus, Amit P. Sheth Oct 1994

The "Infoharness" Information Integration Platform, Leon Shklar, Satish Thatte, Howard Marcus, Amit P. Sheth

Kno.e.sis Publications

The "InfoHarness" information integration platform, tools, and services being developed at Bellcore are aimed at providing integrated and rapid access to huge amounts of heterogeneous information independent of the type, representation, and location of information. InfoHarness provides advanced search and browsing capabilities without imposing the burden of restructuring, reformatting or relocating information on information suppliers or creators. This is achieved through object-oriented encapsulation of information and the associated meta-information (e.g., type, location, access rights, owner, creation date, etc.). The meta-information extraction methods ensure rapid and largely automatic creation of information repositories. A gateway that supports access to InfoHarness repositories from …

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Student Fact Book, Fall 1994, Wright State University, Office Of Student Information Systems, Wright State University Oct 1994

Student Fact Book, Fall 1994, Wright State University, Office Of Student Information Systems, Wright State University

Wright State University Student Fact Books

The student fact book has general demographic information on all students enrolled at Wright State University for Fall Quarter, 1994.

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Nondestructive Mapping Of Carrier Concentration And Dislocation Density In N(+)-Type Gaas, David C. Look, D. C. Walters, M. G. Mier, J. R. Sizelove Oct 1994

Nondestructive Mapping Of Carrier Concentration And Dislocation Density In N(+)-Type Gaas, David C. Look, D. C. Walters, M. G. Mier, J. R. Sizelove

Physics Faculty Publications

Transmission mappings (500 μm×500 μm resolution) at wavelengths of 0.9–1.5 μm on 3 in., n+‐GaAs wafers (n≂1–2×1018 cm-3) correlate well with carrier concentration n, measured by the Hall effect, and dislocation density, as confirmed by KOH etch‐pit patterns. The absorption for λ≳1.0 μm (below band edge) varies directly with n via free‐carrier interconduction‐band transitions, while the absorption for λ≲0.95 μm (near band edge) varies inversely with n because of band‐filling effects. Both phenomena are highly useful for n+‐GaAs wafer characterization.

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Diamagnetic Shifts Of Excitons Associated With Symmetrical And Antisymmetric Wave Functions In Coupled Inxga1-Xas-Gaas Quantum Wells, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz Oct 1994

Diamagnetic Shifts Of Excitons Associated With Symmetrical And Antisymmetric Wave Functions In Coupled Inxga1-Xas-Gaas Quantum Wells, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz

Physics Faculty Publications

Magneto‐optical data obtained from photoluminescence and photoluminescence excitation measurements performed in the presence of applied magnetic fields were used to determine the diamagnetic shifts of free excitons. The samples studied were coupled InxGa1−xAs–GaAs quantum wells. In all cases the excitons associated with antisymmetric wave functions were found to have larger diamagnetic shifts than the excitons associated with symmetric wave functions. This suggests that the excitons associated with antisymmetric wave functions have a smaller binding energy than excitons associated with symmetric wave functions. These properties are consistent with the fact that excitons associated with antisymmetric wave …

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Magnetoluminescence Studies In Gaas-Alxga1-Xas Single Heterojunctions - Observation Of Parity-Forbidden Landau-Level Transitions, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz, R. Jones, K. K. Bajaj Oct 1994

Magnetoluminescence Studies In Gaas-Alxga1-Xas Single Heterojunctions - Observation Of Parity-Forbidden Landau-Level Transitions, D. C. Reynolds, David C. Look, B. Jogai, C. E. Stutz, R. Jones, K. K. Bajaj

Physics Faculty Publications

We have observed a number of allowed and parity-forbidden Landau-level transitions in a modulation-doped GaAs-AlxGa1-xAs single heterojunction structure using photoluminescence-excitation spectroscopy at 2 K. The GaAs layer in this structure is 5000 Å thick. From the allowed Landau-level transitions we determine the reduced mass of the electron-hole pair to be 0.07me. Using a heavy-hole mass of 0.45me, we determine the average value of the electron effective mass to be 0.084me. From the parity-forbidden transitions where the hole Landau level is the same but the electron Landau levels are different, we …

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 8, October 1994, College Of Engineering And Computer Science, Wright State University Oct 1994

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 8, October 1994, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

An eight page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Radiative Recombination At The Alxga1-Xas-Gaas Heterostructure Interface By 2-Dimensional Excitons, D. C. Reynolds, David C. Look, B. Jogai, Phil W. Yu, K. Evans, C. E. Stutz, L. Radomsky Sep 1994

Radiative Recombination At The Alxga1-Xas-Gaas Heterostructure Interface By 2-Dimensional Excitons, D. C. Reynolds, David C. Look, B. Jogai, Phil W. Yu, K. Evans, C. E. Stutz, L. Radomsky

Physics Faculty Publications

Radiative recombination from the AlxGa1-xAs-GaAs heterostructure interface was investigated using photoluminescence and photoluminescence-excitation spectroscopy in modulation-doped and undoped samples. This emission is identified as H-band A, resulting from an indirect excitonlike transition in real space. The exciton is made up of a two-dimensional electron in the interface notch and a valence-band hole in the neutral region, having a binding energy of 1.8 meV. The H-band A exciton is directly excited by a free exciton making a vertical transition in real space. H-band A may be a distortion of the vertical direct free exciton in real space …

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Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 7, September 1994, College Of Engineering And Computer Science, Wright State University Sep 1994

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 10, Number 7, September 1994, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

An eight page newsletter created by the Wright State University College of Engineering and Computer Science that addresses the current affairs of the college.

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Reconstruction Of Semiconductor Doping Profile From Lbic Image, Weifu Fang, Kazufumi Ito Aug 1994

Reconstruction Of Semiconductor Doping Profile From Lbic Image, Weifu Fang, Kazufumi Ito

Mathematics and Statistics Faculty Publications

In this paper, the authors study the reconstruction of a semiconductor doping profile or, equivalently, the equilibrium potential, from its LBIC (laser-beam-induced current) image. For the one-dimensional case, the authors first characterize the attainable class of current measurements, and from this they show the nonuniqueness of the inverse problem. Then the reconstruction of the equilibrium potential is reduced to finding two constants subject to some constraints. A reconstruction algorithm is established based on a least squares formulation of the problem. The case of noise-collapsed data is also discussed. For a special case of two-dimensional domain, the authors apply the one-dimensional …

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Deep Traps In Molecular-Beam-Epitaxial Gaas Grown At Low Temperatures, David C. Look, Z-Q. Fang, H. Yamamoto, J. R. Sizelove, M. G. Mier, C. E. Stutz Jul 1994

Deep Traps In Molecular-Beam-Epitaxial Gaas Grown At Low Temperatures, David C. Look, Z-Q. Fang, H. Yamamoto, J. R. Sizelove, M. G. Mier, C. E. Stutz

Physics Faculty Publications

Deep‐level transient spectroscopy has been performed on Si‐doped GaAs layers grown by molecular‐beam epitaxy at substrate temperatures of 400–450 °C. The λ effect is taken into account and overlapping peaks are analyzed numerically. An 0.65 eV electron trap of concentration 2×1016 cm−3 is believed to be related to the AsGa‐associated 0.65 eV Hall‐effect center, and also to the trap EB4 found in electron‐irradiated GaAs.

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Evolving Plane Curves By Curvature In Relative Geometries Ii, Michael E. Gage, Yi Li Jul 1994

Evolving Plane Curves By Curvature In Relative Geometries Ii, Michael E. Gage, Yi Li

Mathematics and Statistics Faculty Publications

In this paper we prove the existence of self-similar solutions to the anisotropic curve shortening equation.

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