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1991

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Articles 61 - 90 of 1470

Full-Text Articles in Physical Sciences and Mathematics

Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman Dec 1991

Knowledge-Based Systems Approach For Offshore Safety Training, B. S. Lee, Venky Shankararaman

Research Collection School Of Computing and Information Systems

A number of training methods has been used within the offshore industry to impart safety knowledge and safe operating skills. In this paper a Knowledge-Based Safety Training architecture is proposed. The architecture uses both expert system and hypertext methods and is also applicable to plants other than offshore platforms. Special attention is given to the types of knowledge dealt with in safety training and how to represent this knowledge and teach it using various teaching strategies.

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Study Of The Heavy Fermion/Spin-Glass System, Ce1-X GdX Al3, Using 155Gd Mossbauer Spectroscopy, Nicholas G. Ruggiero Dec 1991

Study Of The Heavy Fermion/Spin-Glass System, Ce1-X GdX Al3, Using 155Gd Mossbauer Spectroscopy, Nicholas G. Ruggiero

Physics Theses & Dissertations

The magnetic properties of Ce1-xGdx.Al3 have been studied using 155Gd Mossbauer spectroscopy. It has been shown that the magnetic moments of the host GdAl3 are constrained to the basal plane. The magnetic properties of GdAl3 can best be described in the framework of RKKY theory. Prior studies of Ce1-xGdxAl3, have revealed complex magnetic behavior throughout the series. As observed with Mossbauer spectroscopy magnetic ordering occurs for x ≥ 0.5, though not at the reported spin glass temperatures. For x = 0.23 and x = 0.18, the …

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A Case Study In Software Reuse: The Rntds Architecture, Barry J. Stevens Dec 1991

A Case Study In Software Reuse: The Rntds Architecture, Barry J. Stevens

Computer Science Theses & Dissertations

It has been asserted that the most significant gains in software productivity will come from increased levels of software reuse. Some economic models for predicting savings through software reuse exist, but none are based on actual project experience. This paper surveys those models and presents the results of a case study, the Restructured Naval Tactical Data Systems (RNTDS) architecture, in the light of those models. According to the models, software reuse via the RNTDS architecture has enabled the production of fourteen major computer programs at five to twenty-one percent of the cost to create them without software reuse. Organizational characteristics …

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Test 1656: Ford 5640 (16x4) Diesel 16-Speed, Nebraska Tractor Test Lab Nov 1991

Test 1656: Ford 5640 (16x4) Diesel 16-Speed, Nebraska Tractor Test Lab

Nebraska Tractor Tests

EXPLANATION OF THE TEST PROCEDURE General Tractors are tested at the University of Nebraska according to the Agricultural Tractor Test Code approved by the American Society of Agricultural Engineers and the Society of Automotive Engineers or official Nebraska test procedure. The manufacturer selects the tractor to be tested and certifies that it is a stock model. Each tractor is equipped with the common power consuming accessories such as power steering, power lift pump, generator, etc., if available. Power consuming accessories may be disconnected only when the means for disconnecting can be reached from the operating station. An official representative of …

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Characterization Of Knot Complements In The 4-Sphere, Vo Thanh Liem, Gerard A. Venema Nov 1991

Characterization Of Knot Complements In The 4-Sphere, Vo Thanh Liem, Gerard A. Venema

University Faculty Publications and Creative Works

Knot complements in S4 are characterized as follows: A connected open set W ⊂ S4 is homeomorphic to the complement of some locally flat 2-sphere in S4 if and only if H1(W) is infinite cyclic, W has one end, and the fundamental group of that end is infinite cyclic. Applications include a characterization of weakly flat 2-spheres in S4 and a complement theorem for 2-spheres in S4.

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Optimal Parallel Algorithms For Periods, Palindromes And Squares (Preliminary Version), Alberto Apostolico, Dany Breslauer, Zvi Galil Nov 1991

Optimal Parallel Algorithms For Periods, Palindromes And Squares (Preliminary Version), Alberto Apostolico, Dany Breslauer, Zvi Galil

Department of Computer Science Technical Reports

No abstract provided.

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A Distributed Object-Oriented Discrete Event-Driven Simulation Environment-Dodese, Min Chen Nov 1991

A Distributed Object-Oriented Discrete Event-Driven Simulation Environment-Dodese, Min Chen

FIU Electronic Theses and Dissertations

A new distributed object-oriented discrete event-driven simulation environment, DODESE, is developed to provide a common framework for simulation model design and implementation. The DODESE can be used to define a simulation including all the simulation objects participating in the simulation while the execution of the simulation can be interactively monitored on DODESE. The DODESE system has combined the strengths of both object-oriented paradigms and data base technology to make computer simulation more powerful and has achieved the goals of object-orientation, distribution, reusability, maintainability and extensibility. The system runs on two Sun workstations concurrently connected by an Ethernet. One of the …

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Gcache: A Generalized Caching Mechanism, Douglas E. Comer, Shawn Ostermann Nov 1991

Gcache: A Generalized Caching Mechanism, Douglas E. Comer, Shawn Ostermann

Department of Computer Science Technical Reports

No abstract provided.

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Representation Requirements For Supporting Knowledge-Based Construction Of Decision-Models In Medicine, Tze-Yun Leong Nov 1991

Representation Requirements For Supporting Knowledge-Based Construction Of Decision-Models In Medicine, Tze-Yun Leong

Research Collection School Of Computing and Information Systems

This paper analyzes the medical knowledge required for formulating decision models in the domain of pulmonary infectious diseases (PIDs) with acquired immunodeficiency syndrome (AIDS). Aiming to support dynamic decision-modeling, the knowledge characterization focuses on the ontology of the clinical decision problem. Relevant inference patterns and knowledge types are identified.

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Volume 4 - November 17, 1991 Nov 1991

Volume 4 - November 17, 1991

What on Earth

What on Earth was a short-run student publication by the Providence College Environmental and Wildlife Club. (Volume 4 - November 17, 1991 - 8 pages total.)

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Magnetic And Structural Properties Of Co/Cr Multilayers With In-Plane Anisotropy, D. Wang, David J. Sellmyer Nov 1991

Magnetic And Structural Properties Of Co/Cr Multilayers With In-Plane Anisotropy, D. Wang, David J. Sellmyer

David Sellmyer Publications

Previously we studied the effect of Cr spacer layer on in-plane coercivity in Co/Cr multilayered films. It was found that the high coercivity is related to the easy axis in-plane orientation and the character of the composition modulation. In this paper, the dependence of the saturation magnetization as a function of Co layer thickness is used to study the interface structure. The layer structure is confirmed by small angle x-ray diffractometry for typical films. The magnetic interaction among the grains is studied by examining deviation from the behavior predicted by the Wohlfarth model for noninteracting single-domain particles. Journal of Applied …

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Studies Of Domain Dynamics In Amorphous Dy/Fe Multilayers, Roger D. Kirby, J.X. Shen, Z.S. Shan, David J. Sellmyer Nov 1991

Studies Of Domain Dynamics In Amorphous Dy/Fe Multilayers, Roger D. Kirby, J.X. Shen, Z.S. Shan, David J. Sellmyer

Roger Kirby Publications

Compositionally-modulated Dy/Fe films were prepared by dc magnetron sputtering onto glass substrates. For this series of samples, the Dy thickness was fixed at 5 Å, while the Fe thickness was varied from 4 to 6 Å. To study the magnetization reversal, the samples were first saturated. The magnetic field was then reversed to a value near the coercive field, and the Kerr rotation was measured as a function of time after reversal. We interpret our results in terms of the model of domain reversal first described by Fatuzzo for ferroelectrics. For some Fe thicknesses, we found that the reversal process …

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Development Of The Gd(0001) Band Structure With Film Thickness, Dongqi Li, W. Hutchings, Peter A. Dowben, Rong-Tzong Wu, C. Hwang, M. Onellion, A.B. Andrews, J.L. Erskine Nov 1991

Development Of The Gd(0001) Band Structure With Film Thickness, Dongqi Li, W. Hutchings, Peter A. Dowben, Rong-Tzong Wu, C. Hwang, M. Onellion, A.B. Andrews, J.L. Erskine

Peter Dowben Publications

By growing gadolinium films on W(110), it has been possible to observe the development of the Gd(0001) band structure with increasing film thickness. The changes in the 5d bands as a result of exposure to oxygen or the development of the valence-band structure with increasing film thickness lead to changes in the 5p multiplet oscillator strengths. These changes are a result of the influence of the band structure upon the final-state effects that give rise to such multiplet structures. This study provides conclusive evidence that there is a 5d contribution to the shallow 5p multiplet photoemission …

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Fabricating Magnetic Co-Ni-C Thin-Film Alloys By Organometallic Chemical Vapor Deposition, Yoon-Gi Kim, Dongjin Byun, C. Hutchings, Peter A. Dowben, H. Hejase, K. Schröder Nov 1991

Fabricating Magnetic Co-Ni-C Thin-Film Alloys By Organometallic Chemical Vapor Deposition, Yoon-Gi Kim, Dongjin Byun, C. Hutchings, Peter A. Dowben, H. Hejase, K. Schröder

Peter Dowben Publications

We have deposited CoxNiy-C films with a variety of compositions to verify dependence of the saturation magnetization on the composition. These experiments suggest that we can produce CoxNiy-C films with a variety of magnetic properties. The CoxNiy-C films were fabricated by ultraviolet decomposition of cobaltocene and nickelocene. We demonstrated that the photolytic decomposition of these metallocenes produces cyclopentadienyl (C5H5) species, consistent with recent studies of the energetics of the ligand metal bonds.

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Temperature And Thickness Dependence Of Coercivity And Magnetization Of Co/Cu And Co/Si Multilayers, S. Nafis, John A. Woollam, Z.S. Shan, David J. Sellmyer Nov 1991

Temperature And Thickness Dependence Of Coercivity And Magnetization Of Co/Cu And Co/Si Multilayers, S. Nafis, John A. Woollam, Z.S. Shan, David J. Sellmyer

David Sellmyer Publications

Co/Cu and Co/Si multilayers of total thickness ~3000 Å were prepared by rf and dc magnetron sputtering. The nominal thicknesses of the individual layers were in the range of 4 to 100 Å. A large coercivity (Hc) at 10 K was observed for very thin layers of Co in Co/Cu samples, and it decreased with increase of the Co layer thickness. For very thin layers of Co in Co/Cu samples, the layer behaved superparamagnetically. Similar behavior was not to be observed in Co/Si samples. With increased substrate temperature (Ts) during deposition, Hc was …

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The Process-Controlled Magnetic Properties Of Nanostructured Co/Ag Composite Films, Sy_Hwang Liou, S. Malhotra, Z.S. Shan, David J. Sellmyer, S. Nafis, John A. Woollam, C.P. Reed, R.J. Deangelis, G.M. Chow Nov 1991

The Process-Controlled Magnetic Properties Of Nanostructured Co/Ag Composite Films, Sy_Hwang Liou, S. Malhotra, Z.S. Shan, David J. Sellmyer, S. Nafis, John A. Woollam, C.P. Reed, R.J. Deangelis, G.M. Chow

Sy-Hwang Liou Publications

Nanostructured Co/Ag composite films were prepared by magnetron sputtering using a single target. The average crystallite sizes of Co and Ag in the films depend on the deposition conditions. As the substrate temperature increases from 100 °C to 600 °C, the average Ag crystallite size increases from 39 to 452 Å, and the average Co crystallite size increases from Å in the film with 39 vol. % of Co. The films with 39 vol. % of Co and prepared at 400 °C substrate temperature showed a maximum magnetic coercivity of 565 Oe at 6 K. We have studied the correlation …

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Temperature And Layer-Thickness Dependencies Of Kerr Rotation In Dy/Co Multilayers, Z.S. Shan, J.X. Shen, Roger D. Kirby, Sy_Hwang Liou, David J. Sellmyer Nov 1991

Temperature And Layer-Thickness Dependencies Of Kerr Rotation In Dy/Co Multilayers, Z.S. Shan, J.X. Shen, Roger D. Kirby, Sy_Hwang Liou, David J. Sellmyer

Sy-Hwang Liou Publications

Amorphous Dy/Co multilayers with the individual layer thickness between 4 and 10 Å in steps of 0.5 to 1 Å were studied systematically over the temperature range 100–300 K. The Kerr rotation increases as temperature decreases, or as Co content increases and the coercivity increases both in the low temperature region and in the vicinity of the compensation point. These characteristics were analyzed in terms of simple models of the magnetic structure and magnetization reversal.

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Sputtering Pressure Effect On Microstructure Of Surface And Interface, And On Coercivity Of Co/Pt Multilayers, Ping He, William A. Mcgahan, S. Nafis, John A. Woollam, Z.S. Shan, Sy_Hwang Liou, F. Sequeda, T. Mcdaniel, H. Do Nov 1991

Sputtering Pressure Effect On Microstructure Of Surface And Interface, And On Coercivity Of Co/Pt Multilayers, Ping He, William A. Mcgahan, S. Nafis, John A. Woollam, Z.S. Shan, Sy_Hwang Liou, F. Sequeda, T. Mcdaniel, H. Do

Sy-Hwang Liou Publications

Thin Co/Pt multilayers were prepared on Si and glass substrates by sputtering with Ar pressures ranging from 2.5 to 15 mTorr. The bilayer structure of the samples was Co(3 Å)/Pt(15 Å)×17, and all samples had the easy axis of magnetization perpendicular to the sample surface as determined with a SQUID magnetometer. All samples retained the layered structure, as revealed by low-angle x-ray diffraction. In addition, diffraction peaks due to the formation of Co-Pt compounds (presumably at the interfaces between Co and Pt) were identified. The coercivity of samples changed from about 400 Oe for films deposited at low Ar sputtering …

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Effects Of Replication On The Duration Of Failure In Distributed Databases, Donald B. Johnson, Larry Raab Nov 1991

Effects Of Replication On The Duration Of Failure In Distributed Databases, Donald B. Johnson, Larry Raab

Computer Science Technical Reports

Replicating data objects has been suggested as a means of increasing the performance of a distributed database system in a network subject to link and site failures. Since a network may partition as a consequence of such failures, a data object may become unavailable from a given site for some period of time. In this paper we study duration failure, which we define as the length of time, once the object becomes unavailable from a particular site, that the object remains unavailable. We show that, for networks composed of highly-reliable components, replication does not substantially reduce the duration of failure. …

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Availability Issues In Data Replication In Distributed Database, Donald B. Johnson, Larry Raab Nov 1991

Availability Issues In Data Replication In Distributed Database, Donald B. Johnson, Larry Raab

Computer Science Technical Reports

Replication of data at more than one site in a distributed database has been reported to increase the availability in data in systems where sites and links are subject to failure. We have shown in results summarized in this paper that in many interesting cases the advantage is slight. A well-placed single copy is available to transactions almost as much of the time as is correct replicated data no matter how ingeniously it is managed. We explain these findings in terms of the behavior of the partitions that form in networks where components fail. We also show that known and …

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An Organization Of Sparse Gauss Elimination For Solving Pdes On Distributed Memory Machines, Mo Mu, John R. Rice Nov 1991

An Organization Of Sparse Gauss Elimination For Solving Pdes On Distributed Memory Machines, Mo Mu, John R. Rice

Department of Computer Science Technical Reports

No abstract provided.

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Single-Electron Charging Effects In Insulating Wires, Venkat Chandrasekhar, Zvi Ovadyahu, Richard A. Webb Nov 1991

Single-Electron Charging Effects In Insulating Wires, Venkat Chandrasekhar, Zvi Ovadyahu, Richard A. Webb

Faculty Publications

We present measurements of the transport properties of 0.75-μm-long, narrow, insulating indium oxide wires and rings. These devices have no apparent tunnel barriers, yet they exhibit effects similar to those found in series arrays of very small-capacitance tunnel junctions: highly nonlinear I-V characteristics and a zero-bias conductance which is periodic in a voltage applied by means of a lateral gate. These effects are due to the influence of single-electron charging on transport through localized states in the insulating regime.

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How To Count Quickly And Accurately: A Unified Analysis Of Probabilistic Counting And Other Related Problems, Peter Kirschenhofer, Helmut Prodinger, Wojciech Szpankowski Nov 1991

How To Count Quickly And Accurately: A Unified Analysis Of Probabilistic Counting And Other Related Problems, Peter Kirschenhofer, Helmut Prodinger, Wojciech Szpankowski

Department of Computer Science Technical Reports

No abstract provided.

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A Declarative View Of Inheritance In Logic Programming, M. Bugliesi Nov 1991

A Declarative View Of Inheritance In Logic Programming, M. Bugliesi

Department of Computer Science Technical Reports

No abstract provided.

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Measurements Of Deuteron Threshold Electrodisintegration: A Probe Of Short-Range Meson Exchange, K S. Lee, W Schmitt, H Baghaei, S Churchwell, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson, K Wang Nov 1991

Measurements Of Deuteron Threshold Electrodisintegration: A Probe Of Short-Range Meson Exchange, K S. Lee, W Schmitt, H Baghaei, S Churchwell, R S. Hicks, R A. Miskimen, Gerald Alvin Peterson, K Wang

Gerald Alvin Peterson

The threshold electrodisintegration of the deuteron was measured with good energy resolution to a maximum four-momentum transfer squared of 42 fm-2. The data are compared with meson exchange calculations that show sensitivity to the choice of exchange-current form factor, the nucleon electromagnetic form factors, and the nucleon-nucleon potential. While conventional theories can give a reasonable description of the data, comparison of the data with quark cluster calculations shows poor agreement.

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Unstructured Scheduling In Parallel Pde Sparse Solvers On Distributed Memory Machines, Mo Mu, John R. Rice Nov 1991

Unstructured Scheduling In Parallel Pde Sparse Solvers On Distributed Memory Machines, Mo Mu, John R. Rice

Department of Computer Science Technical Reports

No abstract provided.

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Dmsp F7 Observations Of A Substorm Field‐Aligned Current, R. E. Lopez, Harlan E. Spence, C. Meng Nov 1991

Dmsp F7 Observations Of A Substorm Field‐Aligned Current, R. E. Lopez, Harlan E. Spence, C. Meng

Physics & Astronomy

In this paper we present observations of a substorm field-aligned current (FAC) system that DMSP F7 traversed just after 0300 UT on April 25, 1985. Ground magnetometer data show that a major substorm was in progress at that time and that DMSP F7 flew through a region of predominantly upward FAC. The DMSP F7 magnetic field data are consistent with this interpretation. The precipitating particle data suggest that there were three distinct large-scale FAC systems. In ascending latitude these were a downward current, an upward current, and a paired upward/downward current system. We identify the first current, which was coincident …

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Variation Of Superparamagnetic Properties With Iron Loading In Mammalian Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt Nov 1991

Variation Of Superparamagnetic Properties With Iron Loading In Mammalian Ferritin, Richard B. Frankel, G. C. Papaefthymiou, G. D. Watt

Physics

The average blocking temperatures of ferritin molecules containing differing amounts of iron were determined by Mossbauer spectroscopy. The results imply that the magnetic anisotropy of the ferritin core particles is a function of particle volume. By addition of 57Fe to ferritin core particles it was determined that, at a given temperature within the superpara-magnetic temperature region, the “last-in” ferric ions have average relaxation times that are shorter than those of the bulk ferric ions.

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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 Nov 1991

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.

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More Upper Bounds On The 3-Rewriteability Of Non-3-Rewriteable Groups, Eric Wepsic Nov 1991

More Upper Bounds On The 3-Rewriteability Of Non-3-Rewriteable Groups, Eric Wepsic

Mathematical Sciences Technical Reports (MSTR)

We find an upper bound on the probability that a randomly selected triple in a group is 3-rewriteable, and a bound for the core set rewriteability.

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