Physical Sciences and Mathematics Commons^™

Using Flexible Transactions To Support Multisystem Telecommunication Applications, Mansoor Ansari, Linda Ness, Marek Rusinkiewicz, Amit P. Sheth

Kno.e.sis Publications

Service order provisioning is an important telecommunication application that automates the process of providing telephone services in response to the customer requests. It is an example of a multi-system application that requires access to multiple, independently developed application systems and their databases. In this paper, we describe the design and implementation of a prototype system1 that supports the execution of the Flexible Transactions and its use to develop the service order provisioning application. We argue that such approach may be used to support the development of multi-system, flow-through processing applications in a systematic and organized manner. Its advantages include fast …

Traps In Semi-Insulating Inp Studied By Thermally Stimulated Current Spectroscopy, Z. Q. Fang, David C. Look, J. H. Zhao

Physics Faculty Publications

Traps in Fe‐doped semi‐insulating InP samples have been studied by thermally stimulated current spectroscopy with IR (hν≤1.12 eV) excitation at 81 K. The possible involvement of native defects in determining the compensation mechanisms is suggested based on the observation of other than the usual 0.64 eV Fe‐related activation energy for the dark current in one of the four samples supplied from different sources. A metastable behavior of traps in another sample was found and explained by a charge‐controlled defect reaction model. Three out of the six traps observed are suggested to be electron traps and one among the …

Defect Models In Electron-Irradiated N-Type Gaas, B. Ziebro, Joseph W. Hemsky, David C. Look

Physics Faculty Publications

1 MeV electron irradiation has been performed in degenerate, n‐type (n≂2×10¹⁷ cm^-3), molecular beam epitaxial GaAs layers, and Hall effect measurements have been carried out during the irradiation in order to get accurate defect production data. The results have been fitted with statistical models, and are most consistent with the usual E1 (E_C-0.045 eV) and E2 (E_C-0.15 eV) levels being the (-/0) and (0/+) transitions of the As vacancy, respectively. Also, an acceptor well below EC-0.15 eV is produced at a much higher rate than that of E1 and E2.

Inverse Problems For Metal Oxide Semiconductor Field-Effect Transistor Contact Resistivity, Weifu Fang, Ellis Cumberbatch

Mathematics and Statistics Faculty Publications

Inverse problems arising from the identification of transistor contact resistivity and contact window location are studied. A one-point boundary measurement of the potential is shown to be sufficient to identify each from a one-parameter monotone family, and such identification is both stable and continuously dependent on the parameter. For a nonmonotone family of locations with resistivity given, similar results are obtained for measurement made on almost all boundary points.

Native Donors And Acceptors In Molecular-Beam Epitaxial Gaas Grown At 200 Degrees C, David C. Look, D. C. Walters, M. Mier, C. E. Stutz, S. K. Brierley

Physics Faculty Publications

Absorption measurements at 1.1 and 1.2 μm were used along with the known electron and hole photoionization cross sections for EL2 to determine deep donor (EL2‐like) and acceptor concentrations N_D=9.9×10¹⁹ and N_A=7.9×10¹⁸ cm⁻³, respectively, in a 2‐μm‐thick molecular‐beam epitaxial GaAs layer grown at 200 °C on a 2‐in.‐diam semi‐insulating wafer. Both lateral and depth uniformities of N_D over the wafer were excellent as was also the case for the conductivity. Band conduction was negligible compared to hopping conduction at 296 K as evidenced by the lack of a measurable Hall coefficient.

Mechanisms For Gaas Surface Passivation By A Molecular-Beam Epitaxial Cap Layer Grown At 200-Degrees-C, David C. Look, D. C. Walters, C. E. Stutz, K. R. Evans, J. R. Sizelove

Physics Faculty Publications

A thin, undoped, molecular beam epitaxial (MBE) GaAs cap layer grown on top of an n‐type conductive layer significantly reduces the free‐electron depletion from the latter. By analyzing electron transfer to surface, interface, and bulk acceptor states in the cap, as a function of cap thickness, we show that either (1) the usual E_C−0.7 eV surface states are absent, (2) a dense donor near E_C−0.4 eV exists or (3) a high donor interface charge (∼5×10¹² cm⁻²) is present. Any of these conclusions constitutes an important new aspect of low‐temperature MBE GaAs.

Algorithms For Structural Schema Integration, James Geller, Ashish Mehra, Yehoshua Perl, Erich Neuhold, Amit P. Sheth

Kno.e.sis Publications

Current view and schema integration methodologies are driven by semantic considerations, and allow integration of objects only if that is valid from semantic and structural viewpoints. We had introduced a new integration technique called structural integration. It permits integration of objects that have structural similarities, even if they differ semantically. This technique uses the object-oriented Dual Model which separates the representation of structure and semantics.

In this paper we introduce algorithms for structural integration. We apply these algorithms to integrate two views of a large university database schema which had significant structural similarities but differed semantically.

Incorporation Of Si And Al In Low Temperature Mbe Gaas, M. O. Manasreh, K. R. Evans, C. E. Stutz, David C. Look

Physics Faculty Publications

The localized vibrational modes (LVMs) of silicon donor (Si_Ga) and aluminum isovalent (Al_Ga) impurities in molecular beam epitaxial GaAs layers grown at various temperatures are studied using the infrared absorption technique. It is found that the total integrated absorption of these impurities LVMs is decreased as the growth temperature decreases. This finding suggests a nonsubstitutional incorporation of Si and Al in GaAs layers grown at 200 °C. On the other hand, a subtitutional incorporation is obtained in GaAs layers grown at temperatures higher than 350 °C. A recovery of the Si_Ga LVMs in GaAs layers …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 8, Number 5, May 1992, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Incorporation Of Silicon And Aluminum In Low-Temperature Molecular-Beam Epitaxial Gaas, M. O. Manasreh, K. R. Evans, C. E. Stutz, David C. Look, Joseph Hemsky

Physics Faculty Publications

The localized vibrational modes (LVMs) of silicon donor (Si_Ga) and aluminum isovalent (Al_Ga) impurities in molecular beam epitaxial GaAs layers grown at various temperatures are studied using the infrared absorption technique. It is found that the total integrated absorption of these impurities LVMs is decreased as the growth temperature decreases. This finding suggests a nonsubstitutional incorporation of Si and Al in GaAs layers grown at 200 °C. On the other hand, a subtitutional incorporation is obtained in GaAs layers grown at temperatures higher than 350 °C. A recovery of the Si_Ga LVMs in GaAs layers …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 8, Number 4, April 1992, 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 College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 8, Number 3, March 1992, 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 College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 8, Number 2, February 1992, 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.

Electron-Paramagnetic-Resonance Study Of Gaas Grown By Low-Temperature Molecular-Beam Epitaxy, H. J. Vonbardeleben, M. O. Manasreh, David C. Look, K. R. Evans, C. E. Stutz

Physics Faculty Publications

Electron-paramagnetic-resonance results demonstrate an arsenic-antisite related deep donor defect to be the dominant native defect in GaAs layers grown by low-temperature molecular-beam epitaxy (LTMBE). This defect is different from the EL2-related native arsenic-antisite defect. The thermal-equilibrium concentration of 3×1018 cm−3 ionized AsGa defects directly shows the additional presence of unidentified acceptor defects in the same concentration range. The defect distribution in GaAs grown by LTMBE is unstable under thermal annealing at T≳500 °C.

On The Asymptotic Behavior And Radial Symmetry Of Positive Solutions Of Semilinear Elliptic Equations In Rn. I. Asymptotic Behavior, Yi Li, Wei-Ming Ni

Mathematics and Statistics Faculty Publications

No abstract provided.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 8, Number 1, January 1992, 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.

Executing Multidatabase Transactions, Mansoor Ansari, Marek Rusinkiewicz, Linda Ness, Amit P. Sheth

Kno.e.sis Publications

In a multidatabase environment, the traditional transaction model has been found to be too restrictive. Therefore, several extended transaction models have been proposed in which some of the requirements of transaction, such as isolation or atomicity, are optional. The authors describe one of such extensions, the flexible transaction model and discuss the scheduling of transactions involving multiple autonomous database systems managed by heterogeneous DBMS.

The scheduling algorithm for flexible transactions is implemented using L.0, a logically parallel language which provides a framework for concisely specifying the multidatabase transactions and for scheduling them. The key aspects of a flexible transaction specification, …

Boundary Velocity Control Of Incompressible-Flow With An Application To Viscous Drag Reduction, Max D. Gunzberger, Lisheng Hou, Tom Svobodny

Mathematics and Statistics Faculty Publications

An optimal boundary control problem for the Navier-Stokes equations is presented. The control is the velocity on the boundary, which is constrained to lie in a closed, convex subset of H^1/2 of the boundary. A necessary condition for optimality is derived. Computations are done when the control set is actually finite-dimensional, resulting in all application to viscous drag reduction.

Uniqueness Of Radial Solutions Of Semilinear Elliptic Equations, Man Kam Kwong, Yi Li

Mathematics and Statistics Faculty Publications

E. Yanagida recently proved that the classical Matukuma equation with a given exponent has only one finite mass solution. We show how similar ideas can be exploited to obtain uniqueness results for other classes of equations as well as Matukuma equations with more general coefficients.

Alloy Scattering In P-Type Alxga1-Xas, David C. Look, D. K. Lorance, J. R. Sizelove, C. E. Stutz, K. R. Evans, D. W. Whitson

Physics Faculty Publications

The hole mobility of Be‐doped ( ~ 2 × 10¹⁷ cm^-3) AlxGa1-xAs, for x=0–1, is analyzed both theoretically and experimentally. Alloy scattering is very important, and in fact reduces the hole mobility from 150 to less than 90 cm²/V s at x=0.5. The main parameter in the alloy scattering formulation, the alloy potential Eal, is found to be about 0.5 eV for p‐type AlxGa1-xAs.

Densities And Vibrational Distribution Of H3+ In The Jovian Auroral Ionosphere, Y. H. Kim, Jane L. Fox, H. S. Porter

Physics Faculty Publications

Observations of the H₃⁺ infrared emission at 2 and 4 μm have suggested that H₃⁺ is in local thermodynamic equilibrium (LTE) in the region of the Jovian ionosphere from which the emissions originate. We have tested this assumption by calculating the vibrational distribution of H₃⁺ over the altitude range of 350 to 1500 km above the methane cloud tops (1 to 4 × 10⁻³ μbar). We have constructed a model of the Jovian auroral ionosphere in which the neutral temperatures are enhanced over those of the mid-latitude ionosphere, as suggested by observations and …

On The Asymptotic Behavior And Radial Symmetry Of Positive Solutions Of Semilinear Elliptic Equations In R N Ii. Radial Symmetry, Yi Li, Wei-Ming Ni

Mathematics and Statistics Faculty Publications

The main purpose of this paper is to prove Theorems 1 and 2 of the preceding paper, Part I, together with their extensions and related symmetry results. To make this part essentially self-contained, we shall apply the method developed in Section 2 to equations with radial symmetry. Combining the asymptotic behavior and the "moving plane" technique, we are then able to obtain the desired results.

Specifying Interdatabase Dependencies In A Multidatabase Environment, Marek Rusinkiewicz, Amit P. Sheth, George Karabatis

Kno.e.sis Publications

The problem of interdatabase dependencies and the effect they have on applications updating interdependent data are addressed. A model that allows specifications of constraints among multiple databases in a declarative fashion is proposed. The separation of the constraints from the application programs facilitates the maintenance of data constraints and allows flexibility in their implementation. It allows investigation of various mechanisms for enforcing the constraints, independently of the application programs. By grouping the constraints together, it is possible to check their completeness and discover possible contradictions among them. The concepts of polytransactions, which use interdatabase dependencies to generate a series of …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 8, November 1991, 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.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 7, October 1991, 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.

A Mathematical Model For Outgassing And Contamination, Weifu Fang, Meir Shillor, E. Stahel, E. Epstein, C. Ly, J. Mcniel, E. Zaron

Mathematics and Statistics Faculty Publications

A model for the mathematical description of the processes of outgassing and contamination in a vacuum system is proposed. The underlying assumptions are diffusion in the source, convection and diffusion in the cavity, mass transfer across the source-cavity interface, and a generalization of the Langmuir isotherm for the sorption kinetics on the target. Three approximations are considered where the asymptotic behavior of the model for large time is shown as well as the dependence and sensitivity of the model on some of the parameters. Some numerical examples of the full model are then presented together with a proof of the …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, Volume 7, Number 6, September 1991, 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.

On Compensation And Conductivity Models For Molecular-Beam-Epitaxial Gaas Grown At Low-Temperature, David C. Look

Physics Faculty Publications

Molecular‐beam‐epitaxial GaAs grown at 200 °C has an extremely high (≳10¹⁹ cm⁻³) concentration of As_Ga defects and, after an anneal at 550–600 °C, a high concentration of As precipitates. The relative roles of the As_Ga defects and As precipitates in compensation and conductivity is controversial. Here criteria are developed to distinguish between two existing models.

Boundary C1, Α Regularity For Variational Inequalities, Fang-Hua Lin, Yi Li

Mathematics and Statistics Faculty Publications

No abstract provided.

Analysis And Finite-Element Approximation Of Optimal-Control Problems For The Stationary Navier-Stokes Equations With Distributed And Neumann Controls, Max D. Gunzburger, L. Hou, Tom Svobodny

Mathematics and Statistics Faculty Publications

We examine certain analytic and numerical aspects of optimal control problems for the stationary Navier-Stokes equations. The controls considered may be of either the distributed or Neumann type; the functionals minimized are either the viscous dissipation or the L⁴-distance of candidate flows to some desired flow. We show the existence of optimal solutions and justify the use of Lagrange multiplier techniques to derive a system of partial differential equations from which optimal solutions may be deduced. We study the regularity of solutions of this system. Then, we consider the approximation, by finite element methods, of solutions of the …