Digital Commons Network^™

Specifying And Enforcing Intertask Dependencies, Paul Attie, Munindar Singh, Amit P. Sheth, Marek Rusinkiewicz

Kno.e.sis Publications

Extensions of the traditional atomic transaction model are needed to support the development of multi-system applications or workflows that access heterogeneous databases and legacy application systems. Most extended transaction models use conditions involving events or dependencies between transactions. Intertask dependencies can serve as a uniform framework for defining extended transaction models. In this paper we introduce event attributes needed to determine whether a dependency is enforceable and to properly schedule events in extended transaction models. Using these attributes and a formalization of a dependency into the temporal logic CTL, we can automatically synthesize an automaton that captures the computations that …

Semi-Insulating Nature Of Gas Source Molecular Beam Epitaxial Ingap Grown At Very Low Temperatures, David C. Look, Y. He, J. Ramdani, N. Elmasry, S. M. Bedair

Physics Faculty Publications

In_xGa_1−xP lattice matched to GaAs (x≂0.51) has proven to be useful in many device applications. Here we show that undoped, semi‐insulating InGaP is possible by growing with gas source molecular beam epitaxy at very low temperatures, 150–250 °C. The material grown at about 200 °C is n‐type with a 296‐K resistivity of 9×10⁵ Ω cm, a mobility of 120 cm²/V s, and a donor activity energy of 0.48 eV. When annealed at 600 °C for 1 h, the resistivity increases to greater than 10⁹ Ω cm and the …

Electron-Drift Velocities In Argon-Boron Trichloride Gas-Mixtures, Donald L. Mosteller Jr., Merrill L. Andrews, Jerry D. Clark, A. Garscadden

Physics Faculty Publications

Electron drift velocities were measured for argon gas mixtures containing 25 ppm to 0.5% boron trichloride additive using a pulsed-Townsend drift tube. These results show a marked sensitivity to mixture ratio and the gas mixtures also show negative differential conductivity and strong attachment at low electric field/gas number density.

Electron-Beam Modification Of Gaas Surface-Potential - Measurement Of Richardson Constant, S. M. Lindsay, Joseph W. Hemsky, David C. Look

Physics Faculty Publications

The surface potential of GaAs is strongly modified in the presence of a high‐energy electron beam due to the creation of electron‐hole pairs in the depletion region and the subsequent drift of the holes to the surface where they neutralize surface states. This effect is modeled in terms of a parameter K=A∗T²/I_b(dE/dz)η, where I_b is the beam current density, A∗ is the effective Richardson constant, dE/dz is the beam energy loss per unit length, and η⁻¹ is the average energy required to …

Upper Limits To The Nightside Ionosphere Of Mars, Jane L. Fox

Physics Faculty Publications

The nightside ionosphere of Mars could be produced by electron precipitation or by plasma transport from the dayside, by analogy to the Venus, but few measurements are available. We report here model calculations of upper limits to the nightside ion densities on Mars that would be produced by both mechanisms. For the auroral model, we have adopted the downward traveling portions of the electron spectra measured by the HARP instrument on the Soviet Phobos spacecraft in the Martian plasma sheet and in the magnetotail lobes. For the plasma transport case, we have imposed on a model of the nightside thermosphere, …

Bulletin - Summer, 1993, Civil Aviation Medical Association

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A sixteen page newsletter of the Civil Aviation Medical Association. The newsletter provided news about civil aviation medicine and information related to the organization.

A Framework For Controlling Cooperative Agents, Kuo-Chu Lee, William H. Mansfield, Amit P. Sheth

Kno.e.sis Publications

Presents an overview of the ITX (Interacting Transaction) system, which supports complex interactions among cooperating agents in the presence of user interventions that change application objectives and system failures. The system's components and its unique fixed-point criterion for feedback control of iterative interactions are described. An example of a simplified multimedia teleconferencing application is discussed to illustrate the features of the ITX system.

Prominent Thermally Stimulated Current Trap In Low-Temperature-Grown Molecular-Beam Epitaxial Gaas, Z-Q. Fang, David C. Look

Physics Faculty Publications

By far, the largest thermally stimulated current trap in molecular beam epitaxial GaAs grown at 200–250 °C is T₅, with an activation energy of 0.27 eV and most likely related to V_Ga. After an anneal at 300–350 °C, another trap T₆^☒ appears, with an activation energy of 0.14 eV and closely identified with V_As or the complex, V_As‐As_Ga. Proposed defect reactions in this As‐rich material include V_Ga+As_As→V_As‐As_Ga, and V_Ga+As_Ga→V_Ga‐As_Ga.

Annealing Dynamics Of Molecular-Beam Epitaxial Gaas Grown At 200°C, David C. Look, D. C. Walters, G. D. Robinson, J. R. Sizelove, M. G. Mier, C. E. Stutz

Physics Faculty Publications

By separating a 2‐μm‐thick molecular‐beam‐epitaxial GaAs layer grown at 200 °C from its 650‐μm‐thick substrate, we have been able to obtain accurate Hall‐effect and conductivity data as functions of annealing temperature from 300 to 600 °C. At a measurement temperature of 300 K, analysis confirms that hopping conduction is much stronger than band conduction for all annealing temperatures. However, at higher measurement temperatures (up to 500 K), the band conduction becomes comparable, and a detailed analysis yields the donor and acceptor concentrations and the donor activation energy. Also, an independent absorption study yields the total and charged As_Ga concentrations. …

Analytical Two-Layer Hall Analysis - Application To Modulation-Doped Field-Effect Transistors, David C. Look, C. E. Stutz, Christopher A. Bozada

Physics Faculty Publications

The classical magnetic‐field‐dependent Hall coefficient and conductivity equations are inverted to give the mobilities μ₁ and μ₂ and carrier concentrations n₁ (or p₁) and n₂ (or p₂) in two degenerate bands. The two‐band solution holds for arbitrary magnetic‐field strength as long as quantum effects can be ignored (i.e., kT≳ℏeB/m∗), and it is argued that the analysis can also be applied to two separate layers up to reasonable field strengths. The results are used to determine the two‐dimensional electron gas mobility and carrier concentration in a modulation‐doped field‐effect …

Board Of Trustees Meeting Minutes, June 3-4, 1993

Board of Trustees Minutes

Minutes from the Wright State University Board of Trustees Meeting held on June 3-4, 1993.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 6, June 1993, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

1993-1995 Wright State University Undergraduate Course Catalog, Wright State University

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This is a Wright State University undergraduate course catalog from 1993-1995.

Donor And Acceptor Concentrations In Molecular-Beam Epitaxial Gaas Grown At 300-Degrees-C And 400-Degrees-C, David C. Look, G. D. Robinson, J. R. Sizelove, C. E. Stutz

Physics Faculty Publications

The first Hall‐effect measurements on molecular beam epitaxial GaAs layers grown at the low temperatures of 300 and 400 °C are reported. Two independent methods were used to determine donor N_D and acceptor N_A concentrations and activation energy E_D0, with the following combined results: N_D≂3±1×10¹⁸, N_A≂1.5±1×10¹⁷ cm⁻³, and E_D0=0.645±0.009 eV for the 300 °C layer; N_D≂2±1×10¹⁷, N_A≂7±3×10¹⁶ cm⁻³, and E_D0=0.648±0.003 eV for the 400 °C layer. Thus, the deep donor is …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 5, May 1993, 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.

Wsu Research News, Fall 1993, Office Of Research And Sponsored Programs, Wright State University

WSU Research News

An eight page newsletter of the WSU Research News. The WSU Research News was published monthly beginning in June of 1968 and issued by the Office of Research Development. This newsletter was created to provide information to the WSU faculty about the availability of outside funds for research and educational programs, new developments that may affect availability of funds, and general information on research and educational activities at Wright State University.

Photoquenching And Thermal Recovery Of A Thermally Stimulated Current Peak In Semi-Insulating Gaas, Z-Q. Fang, David C. Look

Physics Faculty Publications

A prominent thermally stimulated current peak T₅ appearing in semi‐insulating GaAs is shown to photoquench under infrared illumination, and then thermally recover at a rate r=2.0×10⁸ exp(−0.26 eV/kT) s⁻¹, exactly the same as that observed for EL2, within experimental error. Two possible explanations exist: (1) T₅ and EL2 are microscopically very similar, probably each with an As_Ga core; or (2) T₅ is an electron trap that only appears to quench and recover with EL2 because EL2 controls the electron lifetime. Several other traps show similar quenching and recovery behavior.

Wsu Research News, Spring 1993, Office Of Research And Sponsored Programs, Wright State University

WSU Research News

An eight page newsletter of the WSU Research News. The WSU Research News was published monthly beginning in June of 1968 and issued by the Office of Research Development. This newsletter was created to provide information to the WSU faculty about the availability of outside funds for research and educational programs, new developments that may affect availability of funds, and general information on research and educational activities at Wright State University.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 4, April 1993, 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.

Wright State University Libraries Access Newsletter Volume 1, Number 3, Spring 1993, Wright State University Libraries

Access Newsletter

A four page newsletter created by Wright State University Libraries that addresses the current affairs of the Libraries.

Board Of Trustees Meeting Minutes, April 1-2, 1993

Board of Trustees Minutes

Minutes from the Wright State University Board of Trustees Meeting held on April 1-2, 1993.

The Guardian, March 31, 1993, Wright State University Student Body

The Guardian Student Newspaper

Nineteen page issue of The Guardian, the official student-run newspaper for Wright State University. The Guardian has been published regularly since March of 1965.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 3, March 1993, 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.

Academic Council Meeting Agenda And Minutes, March 1, 1993, Edgar Rutter

Faculty Senate Minutes and Agendas

Agenda and minutes from the Wright State University Academic Council Meeting held on March 1, 1993.

The Guardian, February 24, 1993, Wright State University Student Body

The Guardian Student Newspaper

Eighteen page issue of The Guardian, the official student-run newspaper for Wright State University. The Guardian has been published regularly since March of 1965.

Task Force On The Status Of Women In The Academy-- Status Of Women Faculty And Unclassified Staff At Wright State University, Mary Beth Pringle

Women's Center Reports

The Task Force on the Status of Women in the Academy has been meeting since September of 1991. The Task Force was charged with addressing two questions.

First, what is the status of women faculty at Wright State University? More particularly,

Why has the number of women on the faculty at WSU not increased during recent years?

What can be done to ensure that a larger number of women appear in the candidate pools for positions?

What can be done to increase the probability of succeeding in hiring women into the ranks of the faculty?

What steps can be taken …

Board Of Trustees Meeting Minutes, February 11-12, 1993

Board of Trustees Minutes

Minutes from the Wright State University Board of Trustees Meeting held on February 11-12, 1993.

Modeling And Analysis For Laser Beam Induced Current Images In Semiconductors, Weifu Fang, Stavros Busenberg, Kazufumi Ito

Mathematics and Statistics Faculty Publications

A mathematical model is developed for the new nondestructive optical technique called laser-beam-induced currents (LBIC), which can be used to detect electrically active regions and defects in semiconductors. The wellposedness of the model equations is shown, and an approximate model that simplifies the numerical implementation of the identification problem is obtained. Some numerical results are presented to show that the approximate model preserves the significant features that the LBIC technique has been experimentally shown to possess.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 9, Number 2, February 1993, 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.

The Full Group Of A Countable Measurable Equivalence Relation, Richard Mercer

Mathematics and Statistics Faculty Publications

We study the group of all ''R-automorphisms'' of a countable equivalence relation R on a standard Borel space, special Borel automorphisms whose graphs lie in R. We show that such a group always contains periodic maps of each order sufficient to generate R. A construction based on these periodic maps leads to totally nonperiodic R-automorphisms all of whose powers have disjoint graphs. The presence of a large number of periodic maps allows us to present a version of the Rohlin Lemma for R-automorphisms. Finally we show that this group always contains copies of free …