Physical Sciences and Mathematics Commons^™

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, May 1991, 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.

On The Relationship Between Parsimonious Covering And Boolean Minimization, Venu Dasigi, Krishnaprasad Thirunarayan

Kno.e.sis Publications

Minimization of Boolean switching functions is a basic problem in the design of logic circuits. The designer first comes up with a switching function expressed in terms of several binary input variables that satisfies the desired functionality, and then attempts to minimize the function as a sum of products or product of sums. It turns out that a sum of products form of a switching function that has no redundancy is a union of prime implicants of the function.

In this paper we would like to explicate some of the relationships of the boolean minimization problem to a formalization of …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, April 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.

The Architecture Of Braid: A System For Bridging Al/Db Systems, Amit P. Sheth, Anthony B. O'Hare

Kno.e.sis Publications

We describe the design of BrAID (a Bridge between Artificial Intelligence and Database Management Systems), an experimental system for the efficient integration of logic based Artificial Intelligence (Al) and database (DB) technologies. Features provided by BrAID include (a) access to conventional DBMSs, (b) support for multiple inferencing strategies, (c) a powerful caching subsystem that manages views and employs subsumption to facilitate the reuse of previously cached data, (d) lazy or eager evaluation of queries submitted by the AI system, and (e) the generation of advice by the AI system to aid in cache management and query execution planning. To discuss …

On Serializability Of Multidatabase Transactions Through Forced Local Conflict, Dimitrios Georgakopoulos, Marek Rusinkiewicz, Amit P. Sheth

Kno.e.sis Publications

The main difficulty in enforcing global serializability in a multidatabase environment lies in resolving indirect transitive conflicts between multidatabase transactions. Indirect conflicts introduced by local transactions are difficult to resolve because the behavior or even the existence of local transactions is not known to the multidatabase system. To overcome these problems, we propose to incorporate additional data manipulation operations in the subtransactions of each multidatabase transaction. We show that if these operations create direct conflicts between subtransactions at each participating local database system, indirect conflicts can be resolved even if the multidatabase system is not aware of their existence. Based …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, March 1991, 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.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, February 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.

The Jovian Ionospheric E Region, Y. H. Kim, Jane L. Fox

Physics Faculty Publications

We have constructed a model of the Jovian ionosphere that includes direct photoionization of hydrocarbon molecules. A high resolution solar spectrum was synthesized from Hinteregger's solar maximum spectrum (F79050N) and high resolution cross sections for photoabsorption by H₂ bands in the range 842 to 1116 Å were constructed. Two strong solar lines and about 30% of the continuum flux between 912 and 1116 Å penetrate below the methane homopause despite strong absorption by CH₄ and H₂. We find that hydrocarbons (mainly C₂H₂) are ionized at a maximum rate of 55 cm^{−3 …}

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, January 1991, 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.

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

Mathematics and Statistics Faculty Publications

Optimal control problems for the stationary Navier-Stokes equations are examined from analytical and numerical points of view. The controls considered are of Dirichlet type, that is, control is effected through the velocity field on (or the mass flux through) the boundary; the functionals minimized are either the viscous dissipation or the L4-distance of candidate flows to some desired flow. We show that optimal solutions exist 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. The n, finite …

Student Fact Book, Fall 1991, 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, 1991.

The Venus Ultraviolet Aurora: A Soft Electron Source, Jane L. Fox, A. I. F. Stewart

Physics Faculty Publications

The Pioneer Venus Orbiter Ultraviolet Spectrometer has recorded continuous but variable emissions of atomic oxygen at 1304 and 1356 Å in images of the nightside of Venus. We show that the observed intensities are consistent with the presence of precipitation of soft electrons into the nightside thermosphere. Model calculations are presented in which upper and lower limits to the magnitude of the electron flux necessary to produce the observed intensities are derived. Constraints are imposed on the energy spectrum of the electrons by the measured ion densities and by the predicted intensities of other emissions that have not been detected.

Unpinning Of Gaas Surface Fermi Level By 200 Degrees C Molecular Beam Epitaxial Layer, David C. Look, C. E. Stutz, K. R. Evans

Physics Faculty Publications

Previous attempts to passivate the n‐type (100)GaAs surface have significantly reduced only the surface recombination centers, but not the surface acceptors which pin the Fermi level. Here we show that a 100 Å molecular beam epitaxial layer grown at 200 °C reduces the effective surface potential energy − eϕ_s from 0.70 to 0.17 eV, nearly eliminates light sensitivity, and permits nonalloyed ohmic contacts. After a 10 min, 450 °C anneal, − eϕ_s increases only to 0.22 eV.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, November 1990, 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.

Management Of Interdependent Data: Specifying Dependency And Consistency Requirements, Amit P. Sheth, Marek Rusinkiewicz

Kno.e.sis Publications

Multiple databases that serve the needs of various application systems are considered. One of the significant problems in managing these databases is to maintain the related data items consistent to the required degree. This problem is frequently referred to as `redundant data management'. Since the term `redundancy' tends to imply that the data is unwanted or superfluous, the authors use the more general term `management of interdependent data'. Some preliminary ideas in this area are discussed. The problem of managing interdependent data is characterized, and some important types of interdatabase dependency are identified.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, October 1990, 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.

Nonalloyed Ohmic Contacts On Low-Temperature Molecular-Beam Epitaxial Gaas: Influence Of Deep Donor Band, H. Yamamoto, Z-Q. Fang, David C. Look

Physics Faculty Publications

The Ohmic nature of the nonalloyed metal contact on molecular beam epitaxial GaAs grown at 200 °C was studied. The specific contact resistances at room temperature and 120 K were 1.5×10⁻³ and 7.0×10⁻¹ Ω cm², respectively. These values are anomalously low considering that the conduction‐band electron concentration in this material is less than 10¹¹ cm⁻³ at room temperature. The experimental results indicate that the carrier transport at the metal/semiconductor interface is dominated by a dense (∼3×10¹⁹ cm⁻³) EL2‐like deep donor band, rather than the usual conduction band.

Student Fact Book, Fall 1990, 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, 1990.

Berry-Esseen-Type Bounds For Signed Linear Rank Statistics With A Broad Range Of Scores, Munsup Seoh

Mathematics and Statistics Faculty Publications

The Berry-Esseen-type bounds of order N^−1/2 for the rate of convergence to normality are derived for the signed linear rank statistics under the hypothesis of symmetry. The results are obtained with a broad range of regression constants and scores (allowed to be generated by discontinuous score generating functions, but not necessarily) restricted by only mild conditions, while almost all previous results are obtained with continuously differentiable score generating functions. Furthermore, the proof is very short and elementary, based on the conditioning argument.

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, September 1990, 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.

Anomalous Hall-Effect Results In Low-Temperature Molecular-Beam-Epitaxial Gaas - Hopping In A Dense El2-Like Band, David C. Look, D. C. Walters, M. O. Manasreh, J. R. Sizelove, C. E. Stutz, K. R. Evans

Physics Faculty Publications

Molecular-beam-epitaxial GaAs grown at very low temperatures (∼200 °C) exhibits anomalous Hall-effect properties. Here we show conclusively that the room-temperature conduction is due to activated (nearest-neighbor) hopping in a deep defect band of concentration 3×10¹⁹ cm^-3, and energy E_c-0.75 eV, along with conduction due to free carriers thermally excited from this band. At low measurement temperatures, variable-range hopping [σ∝exp(-T₀/T)^1/4] prevails. The conduction-band mobility can be well explained by neutral-deep-donor scattering in parallel with lattice scattering.

Infrared-Absorption Of Deep Defects In Molecular-Beam-Epitaxial Gaas-Layers Grown At 200°C - Observation Of An El(2)-Like Defect, M. O. Manasreh, David C. Look, K. R. Evans

Physics Faculty Publications

Infrared optical absorption and Hall-effect techniques were employed to study deep defects in As-rich molecular-beam-epitaxial GaAs layers grown at very low temperature (200°C). A large ir absorption band was observed between 0.55 eV and the band edge. This band is composed of photoquenchable and photounquenchable components. Photoquenching, thermal recovery from the metastable state, and ir absorption properties of the quenchable defect, of estimated concentration ~3x10¹⁸ cm^-3, are identical to those of EL2. On the other hand, the unquenchable defect, of estimated concentration ~3x10¹⁹ cm^-3, resembles the isolated As_Ga, antisite observed in …

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, May 1990, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

A four 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, April 1990, 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.

Bimodules Over Cartan Subalgebras, Richard Mercer

Mathematics and Statistics Faculty Publications

Given a Cartan subalgebra A of a non Neumann algebra M, the techniques of Feldman and Moore are used to analyze the partial isometries v in M such that v* Av is contained in A. Orthonormal bases for M consisting of such partial isometries are discussed, and convergence of the resulting generalized fourier series is shown to take place in the Bures A-topology. The Bures A-topology is shown to be equivalent to the strong topology on the unit ball of M. These ideas are applied to A-bimodules and to give a simplified and intuitive proof of the Spectral Theorem …

On The Equivalence Of The Operator Equations Xa + Bx = C And X - P(-B)Xp(A)(-1) = W In A Hilbert-Space, P A Polynomial, Tapas Mazumdar, David Miller

Mathematics and Statistics Faculty Publications

We consider the solution of (*) XA+BX = C for bounded operators A,B,C and X on a Hilbert space, A normal. We establish the existence of a polynomial p and a bounded operator W with the property that the unique solution X of (*) also solves X − p(−B)Xp(A)⁻¹ = W uniquely. A known iterative algorithm can be applied to the latter equation to solve (*).

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, March 1990, College Of Engineering And Computer Science, Wright State University

BITs and PCs Newsletter

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

Surface And Interface Free-Carrier Depletion In Gaas Molecular Beam Epitaxial Layers: Demonstration Of High Interface Charge, David C. Look, C. E. Stutz, K. R. Evans

Physics Faculty Publications

Molecular beam epitaxial GaAs layers of electron concentration 1.69×10¹⁷ cm⁻³, and various thicknesses d=0.25, 0.50, 1.00, and 2.00 μm, have been grown on semi‐insulating GaAs substrates and characterized by the Hall effect and capacitance‐voltage (C‐V) techniques. A plot of sheet Hall concentration n_s vs d gives accurate values of (N_D−N_A) and (w_s+w_i), the sum of the surface and interface free‐carrier depletion widths, respectively. The C‐V measurements verify the value of N_D−N_{A …}

Wright State University College Of Engineering And Computer Science Bits And Pcs Newsletter, February 1990, 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.

Surface And Interface Free-Carrier Depletion In Gaas Molecular-Beam Epitaxial Layers: Demonstration Of High Interface Charge, David C. Look, C. E. Stutz, K. R. Evans

Physics Faculty Publications

Molecular beam epitaxial GaAs layers of electron concentration 1.69×10¹⁷ cm⁻³, and various thicknesses d=0.25, 0.50, 1.00, and 2.00 μm, have been grown on semi‐insulating GaAs substrates and characterized by the Hall effect and capacitance‐voltage (C‐V) techniques. A plot of sheet Hall concentration n_s vs d gives accurate values of (N_D−N_A) and (w_s+w_i), the sum of the surface and interface free‐carrier depletion widths, respectively. The C‐V measurements verify the value of N_D−N_{A …}