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1992

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Articles 49861 - 49890 of 52976

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Comparative Pharmacology-Toxicology Of Cocaethylene And Cocaine/ By Yili Wang, Yili Wang Jan 1992

Comparative Pharmacology-Toxicology Of Cocaethylene And Cocaine/ By Yili Wang, Yili Wang

Electronic Theses and Dissertations

No abstract provided.

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Cycle Performance And Heat Transfer Characteristics Of A Heat Pump Using R22/R142b Refrigerant Mixtures, T. S. Kim, J. Y. Shin, S. D. Chang, M. S. Kim, S. T. Ro Jan 1992

Cycle Performance And Heat Transfer Characteristics Of A Heat Pump Using R22/R142b Refrigerant Mixtures, T. S. Kim, J. Y. Shin, S. D. Chang, M. S. Kim, S. T. Ro

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Performance And Reliability Degradation Of A Residential Unitary Air Conditioning System Resulting From A Mismatch Of A 1992 Air Conditioning Unit With A 15-20 Year Old Evaporator, C. Heflin, F. Keller Jan 1992

Performance And Reliability Degradation Of A Residential Unitary Air Conditioning System Resulting From A Mismatch Of A 1992 Air Conditioning Unit With A 15-20 Year Old Evaporator, C. Heflin, F. Keller

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Modelling Adiabatic Capillary Tubes: A Critical Analysis, C. Melo, R. T. S. Ferreira, R. H. Pereira Jan 1992

Modelling Adiabatic Capillary Tubes: A Critical Analysis, C. Melo, R. T. S. Ferreira, R. H. Pereira

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Refrigerant Mixtures As Hcfc-22 Alternatives, M. B. Shiflett, A. Yokozeki, D. B. Bivens Jan 1992

Refrigerant Mixtures As Hcfc-22 Alternatives, M. B. Shiflett, A. Yokozeki, D. B. Bivens

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Pure Refrigerant Condensation On A Single Integral Finned Tube: Vapour Velocity Effects, B. Bella, A. Cavallini, G. A. Longo, L. Rossetto Jan 1992

Pure Refrigerant Condensation On A Single Integral Finned Tube: Vapour Velocity Effects, B. Bella, A. Cavallini, G. A. Longo, L. Rossetto

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Autonomic Distributed Coordinative Control "F-Vpm" For Multiple Air Conditioners With Concurrent Cooling And Heating Operation, J. Okajima, F. Matstuoka, Y. Shibuya Jan 1992

Autonomic Distributed Coordinative Control "F-Vpm" For Multiple Air Conditioners With Concurrent Cooling And Heating Operation, J. Okajima, F. Matstuoka, Y. Shibuya

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Domestic Refrigeraror/Freezer Applications For New Technologies, W. A. Reed Jan 1992

Domestic Refrigeraror/Freezer Applications For New Technologies, W. A. Reed

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Refrigeration Control With Varying Condensing Pressures, R. H. Green, E. A. Technology, O. A. Vinnicombe, G. A. Ibrahim Jan 1992

Refrigeration Control With Varying Condensing Pressures, R. H. Green, E. A. Technology, O. A. Vinnicombe, G. A. Ibrahim

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Lifetime And Reliability Of Small Hermetic Compressors Using A Ternary Blend Hcfc-22/Hfc-152a/Hcfc-L24, P. E. Hansen, L. Finsen Jan 1992

Lifetime And Reliability Of Small Hermetic Compressors Using A Ternary Blend Hcfc-22/Hfc-152a/Hcfc-L24, P. E. Hansen, L. Finsen

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Thermal Diffusivity Measurement Of Refrigerant 22 At Low Pressures Using The Photoacoustic Effect, K. Stephan, J. Biermann Jan 1992

Thermal Diffusivity Measurement Of Refrigerant 22 At Low Pressures Using The Photoacoustic Effect, K. Stephan, J. Biermann

International Refrigeration and Air Conditioning Conference

No abstract provided.

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R134a In Small Commercial Refrigeration System: Some Practical Aspects, K. D. Gerdsmeyer Jan 1992

R134a In Small Commercial Refrigeration System: Some Practical Aspects, K. D. Gerdsmeyer

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Oxygen Radicals In Ulcerative Colitis, Charles F. Babbs Jan 1992

Oxygen Radicals In Ulcerative Colitis, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

This article reviews the pathophysiologic concept that superoxide and hydrogen peroxide, generated by activated leukocytes, together with low-molecular-weight chelate iron derived from fecal sources and from denatured hemoglobin, amplify the inflammatory response and subsequent mucosal damage in patients with active episodes of ulcerative colitis. The putative pathogenic mechanisms reviewed are as follows: ( l ) Dietary iron is concentrated in fecal material owing to normally limited iron absorption. (2) Mucosal bleeding, characteristic of ulcerative colitis, as well as supplemental oral iron therapy for chronic anemia, further conspire to maintain or elevate mucosal iron concentration in colitis. (3) Fenton chemistry, driven …

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Histochemical Demonstration Of Endothelial Superoxide And Hydrogen Peroxide Generation In Ischemic And Reoxygenated Rat Tissues, Charles F. Babbs, Meloney D. Cregor, Stephen F. Badylak Jan 1992

Histochemical Demonstration Of Endothelial Superoxide And Hydrogen Peroxide Generation In Ischemic And Reoxygenated Rat Tissues, Charles F. Babbs, Meloney D. Cregor, Stephen F. Badylak

Weldon School of Biomedical Engineering Faculty Publications

Objective: The aims were to test and evaluate two novel and independent histochemical methods for detecting the initial postischemic burst of superoxide and hydrogen peroxide in buffer perfused rat tissues during reflow after 60 min warm ischemia. Methods: The first is a high manganese/diaminobenzidine technique, in which superoxide oxidises Mn2+ to Mn3+, which in turn oxidizes diaminobenzidine to form amber colored polymers, observable by light microscopy. The second is a high iron/diaminobenzidine technique, in which hydrogen peroxide oxidizes diethylenetriaminepenta-acetate chelated Fe2+ to form intermediate species, which in turn oxidize diaminobenzidine similarly to Mn3+. Various isolated organs of the rat were …

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A Computer-Based, Automated, Telephonic System To Monitor Patient Progress In The Home Setting, Umesh H. Patel, Charles F. Babbs Jan 1992

A Computer-Based, Automated, Telephonic System To Monitor Patient Progress In The Home Setting, Umesh H. Patel, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

In this report we describe an automated, telephonic system to monitor the progress of patients convalescing at home. The system includes a computerized central station that is capable of automated voice communication over the telephone, using voice reproduction, and touch-tone recognition. Peripheral hardware in multiple monitored homes need include only a touch-tone telephone, but may also be augmented by inexpensive, rudimentary diagnostic aids, such as a scale for body weight, a thermometer, or a blood pressure cuff and manometer. Current central hardware includes a NeXT computer, a fax modem, and a specialized telecommunications modem developed specifically for voice telecommunication using …

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Evidence Of Changes In Regional Blood Perfusion In Human Intracranial Tumours During Conductive Interstitial Hyperthermia, U H. Patel, Charles F. Babbs, J A. Deford, W M. Bleyer, J A. Marchosky, C J. Moran Jan 1992

Evidence Of Changes In Regional Blood Perfusion In Human Intracranial Tumours During Conductive Interstitial Hyperthermia, U H. Patel, Charles F. Babbs, J A. Deford, W M. Bleyer, J A. Marchosky, C J. Moran

Weldon School of Biomedical Engineering Faculty Publications

Human intracranial tumours were treated using local heat therapy produced by surgically implanted catheters containing local resistive heating elements. Changes in local tumor blood flow were assessed indirectly from an algorithm based on the bioheat transfer equation. The algorithm used the ratio of catheter power to catheter temperature rise to estimate regional blood perfusion. Local heat therapy produced consistent reductions in local apparent perfusion. Changes in apparent regional perfusion occurred in intriguing patterns that gave clues to possible vascular events of therapeutic significance.

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Self‐Consistent Scattering Matrix Calculation Of The Distribution Function In Semiconductor Devices, Mark A. Stettler, Mark S. Lundstrom Jan 1992

Self‐Consistent Scattering Matrix Calculation Of The Distribution Function In Semiconductor Devices, Mark A. Stettler, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

The scattering matrix approach is a new technique for solving the Boltzmann equation in devices. We report a self-consistent application of the technique to realistic silicon devices exhibiting strong nonlocal effects. Simulation of a hot-electron, n-i-n diode demonstrates that the new technique efficiently and accurately reproduces Monte Carlo results without the statistical noise, allowing much tighter convergence with Poisson’s equation.

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Minority Hole Mobility In N+ Gaas, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel Jan 1992

Minority Hole Mobility In N+ Gaas, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel

Department of Electrical and Computer Engineering Faculty Publications

The minority hole diffusivity, or equivalently the hole mobility, was measured in n+GaAs with the zero‐field time‐of‐flight technique. The minority hole mobility was measured for the donor doping range of 1.3×1017 cm−3 to 1.8×1018 cm−3 and was found to vary from 235 to 295 cm2/V s. At the lower doping level, the minority hole mobility is comparable to the corresponding majority hole mobility, but at 1.8×1018 cm−3 the minority hole mobility was 30% higher than the majority carrier hole mobility. These results have important implications for the design of devices such …

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Microsecond Lifetimes And Low Interface Recombination Velocities In Moderately Doped N-Gaas Thin Films, Gregory Benedict Lush, D. H. Levi, H. F. Macmillan, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel Jan 1992

Microsecond Lifetimes And Low Interface Recombination Velocities In Moderately Doped N-Gaas Thin Films, Gregory Benedict Lush, D. H. Levi, H. F. Macmillan, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel

Department of Electrical and Computer Engineering Faculty Publications

We have observed lifetimes greater than 1 ps in moderately doped, thin film, n-GaAs/A1a,Gae,As double heterostructure membranes formed by etching away the substrate. We attribute these ultralong lifetimes to enhanced photon recycling caused by the removal of the substrate. Nonradiative recombination in the bulk and at the interfaces is very low; the upper limit of the interface recombination velocity is 25 cm/S.-Such long lifetimes in GaAs doped at N,= 1.3 X 10” cme3 suggest that thin-film solar cells offer a potential option for achieving very high efficiencies.

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Comparative Study Of Minority Electron Properties In P+-Gaas Doped With Beryllium And Carbon, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel, B. M. Keyes, T. J. De Lyon, J. M. Woodall Jan 1992

Comparative Study Of Minority Electron Properties In P+-Gaas Doped With Beryllium And Carbon, Michael L. Lovejoy, Michael R. Melloch, Mark S. Lundstrom, R. K. Ahrenkiel, B. M. Keyes, T. J. De Lyon, J. M. Woodall

Department of Electrical and Computer Engineering Faculty Publications

Minority electron properties in p+‐GaAs doped with beryllium (Be) and with carbon (C) are reported. Measurements of essentially identical responses for structures differing only in dopant element demonstrate that the diffusivity (Dn) and the diffusion lengths (Ln) are the same in p+‐GaAs doped to ∼1019 cm−3 with Be‐ and C‐dopants. Zero‐field time‐of‐flight analysis yields Dn=35 cm2/s and internal quantum efficiency analysis yields Ln=2.4 μm, which implies a lifetime that is approximately at the estimated radiative limit. In addition, the majority Hall mobility was also found to be identical …

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Minority Electron Transport In Inp/Ingaas Heterojunction Bipolar Transistors, Paul Dodd, Mark S. Lundstrom Jan 1992

Minority Electron Transport In Inp/Ingaas Heterojunction Bipolar Transistors, Paul Dodd, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

Electron transport across the base of InP/InGaAs heterojunction bipolar transistors is examined by Monte Carlo simulation. The base transit times and electron distribution functions are examined as a function of basewidth. Clear ballistic behavior is observed only for extremely thin bases (much less than 100 A). Over the range of basewidths of interest for devices, base transport appears diffusive, but the electrons are very far from thermal equilibrium. The diffusive behavior is shown to arise from the sensitivity of the steady-state carrier population to small amounts of large-angle scattering.

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A Study Of Minority Carrier Lifetime Versus Doping Concentration In N‐Type Gaas Grown By Metalorganic Chemical Vapor Deposition, Gregory Benedict Lush, H. F. Macmillan, B. M. Keyes, D. H. Levi, Michael R. Melloch, R. K. Ahrenkiel, Mark S. Lundstrom Jan 1992

A Study Of Minority Carrier Lifetime Versus Doping Concentration In N‐Type Gaas Grown By Metalorganic Chemical Vapor Deposition, Gregory Benedict Lush, H. F. Macmillan, B. M. Keyes, D. H. Levi, Michael R. Melloch, R. K. Ahrenkiel, Mark S. Lundstrom

Department of Electrical and Computer Engineering Faculty Publications

Time‐resolved photoluminescence decay measurements are used to explore minority carrier recombination in n‐type GaAs grown by metalorganic chemical vapor deposition, and doped with selenium to produce electron concentrations from 1.3×1017 cm−3 to 3.8×1018 cm−3. For electron densities n0<1018 cm−3, the lifetime is found to be controlled by radiative recombination and photon recycling with no evidence of Shockley–Read–Hall recombination. For higher electron densities, samples show evidence of Shockley–Read–Hall recombination as reflected in the intensity dependence of the photoluminescence decay. Still, we find that radiative recombination and photon recycling are important for …

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An Experimental Investigation Of Ternary Refrigerant Blends Performance Proposed As Substitutes For Cfc-12, S. M. Sami, J. Schnotale, J. G. Smale Jan 1992

An Experimental Investigation Of Ternary Refrigerant Blends Performance Proposed As Substitutes For Cfc-12, S. M. Sami, J. Schnotale, J. G. Smale

International Refrigeration and Air Conditioning Conference

No abstract provided.

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Modeling Of Compressor Shell Vibrations Excited By A Rotor Imbalance, D. C. Conrad, W. Soedel Jan 1992

Modeling Of Compressor Shell Vibrations Excited By A Rotor Imbalance, D. C. Conrad, W. Soedel

International Compressor Engineering Conference

No abstract provided.

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An Iterative Interlacing Approach For Synthesis Of Computer-Generated Holograms, 0. K. Ersoy, J. Y. Zhuang, J. Brede Jan 1992

An Iterative Interlacing Approach For Synthesis Of Computer-Generated Holograms, 0. K. Ersoy, J. Y. Zhuang, J. Brede

Department of Electrical and Computer Engineering Technical Reports

A new approach to optimizing computer-generated holograms (CGH's) is discussed. The approach can be summarized most generally as hierarchically designing a number of holograms to add up coherently to a single desired reconstruction. In the case of binary holograms, this approach results in the interlacing (IT) and the iterative interlacing (IIT) techniques. In the IT technique, a number of subholograms are designed and interlaced together to generate the total binary hologram. The first sttbhologram is designed to reconstruct the desired image. The succeeding subholograms are designed to correct the remaining error image. In the IIT technique, the remaining error image …

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Hierarchical Neural Networks With Forward-Backward Training, S-W. Deng, O. K. Ersoy Jan 1992

Hierarchical Neural Networks With Forward-Backward Training, S-W. Deng, O. K. Ersoy

Department of Electrical and Computer Engineering Technical Reports

A forward-backward training algorithm for parallel, self-organizing hierachical neural networks (PSHNN's) is described. Using linear algebra, it is shown that the forward-backward training of an n-stage PSHNN until convergence is equivalent to the pseudo-inverse solution for a single, total network designed in the leastsquares sense with the total input vector consisting of the actual input vector and its additional nonlinear transformations. These results are also valid when a single long input vector is partitioned into smaller length vectors. A number of advantages achieved are small modules for easy and fast learning, parallel implementation of small modules during testing, faster convergence …

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A Generalized Gaussian Image Model For Edge-Preserving Map Estimation, Charles Bouman, Ken Sauer Jan 1992

A Generalized Gaussian Image Model For Edge-Preserving Map Estimation, Charles Bouman, Ken Sauer

Department of Electrical and Computer Engineering Technical Reports

We present a Markov random field model intended to allow realistic edges in maximum a posteriori ( M A P ) image estimates, while providing stable solutions. Similar to the generalized Gaussian distribution used in robust detection and estimation, we proposed the generalized Gaussian Markov random field (GGMRF). This model satisfies several desirable analytical and computational properties for MAP estimation, including continuous dependence of the estimate on the data, invariance of the character of solutions to scaling of data, and a solution which lies at the unique local minimum of the a posteriori log likelihood function. The GGMRF is demonstrated …

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Common Subexpression Induction?, H. G. Dietz Jan 1992

Common Subexpression Induction?, H. G. Dietz

Department of Electrical and Computer Engineering Technical Reports

SIMD (Single Instruction stream, Multiple Data stream) computers can only execute the exact same instruction across all processing elements. This paper presents a new com;piler optimization that transforms multiple distinct code threads so that they have as many instructions in common as possible, hence, SIMD execution time is minimized. For example, SIMD "parallel if" statements typically take the then clause time plus the else clause time to execute, but this new tmnsformation usually can induce identical code sequences for most of the code in the then and else clauses, often yielding a 40% improvement in execution speed. The same principle …

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Electrical Characterization Of Nlpln Structuresin 6h-Sic, Chester Thad Gardner, James A. Cooper, Michael R. Melloch, John W. Palmour, Calvin H. Carter, Jr. Jan 1992

Electrical Characterization Of Nlpln Structuresin 6h-Sic, Chester Thad Gardner, James A. Cooper, Michael R. Melloch, John W. Palmour, Calvin H. Carter, Jr.

Department of Electrical and Computer Engineering Technical Reports

No abstract available.

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Modeling And Simulation Of A Scroll Compressor Using Bond Graphs, D. L. Margolis, S. Craig, G. Nowakowski, M. Inada, M. Dearing Jan 1992

Modeling And Simulation Of A Scroll Compressor Using Bond Graphs, D. L. Margolis, S. Craig, G. Nowakowski, M. Inada, M. Dearing

International Compressor Engineering Conference

No abstract provided.

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