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2000

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Articles 631 - 660 of 2919

Full-Text Articles in Physical Sciences and Mathematics

Observation Of Stratospheric Ozone Depletion Associated With Delta Ii Rocket Emissions, Martin N. Ross, Darin W. Toohey, W. T. Rawlins, E. C. Richard, K. K. Kelly, A. F. Tuck, M. H. Proffitt, Donald E. Hagen, Alfred R. Hopkins, Philip D. Whitefield, J. R. Benbrook, W. R. Sheldon Aug 2000

Observation Of Stratospheric Ozone Depletion Associated With Delta Ii Rocket Emissions, Martin N. Ross, Darin W. Toohey, W. T. Rawlins, E. C. Richard, K. K. Kelly, A. F. Tuck, M. H. Proffitt, Donald E. Hagen, Alfred R. Hopkins, Philip D. Whitefield, J. R. Benbrook, W. R. Sheldon

Physics Faculty Research & Creative Works

Ozone, chlorine monoxide, methane, and submicron particulate concentrations were measured in the stratospheric plume wake of a Delta II rocket powered by a combination of solid (NH4ClO4/Al) and liquid (LOX/kerosene) propulsion systems. We apply a simple kinetics model describing the main features of gas-phase chlorine reactions in solid propellant exhaust plumes to derive the abundance of total reactive chlorine in the plume and estimate the associated cumulative ozone loss. Measured ozone loss during two plume encounters (12 and 39 minutes after launch) exceeded the estimate by about a factor of about two. Insofar as only the …


Development Of Bismaleimide/Cyanate Ester Based Aerospace Polymers For Possible Use In Nasa's Relaunchable Vehicles Program, Brian Sisk Aug 2000

Development Of Bismaleimide/Cyanate Ester Based Aerospace Polymers For Possible Use In Nasa's Relaunchable Vehicles Program, Brian Sisk

Masters Theses & Specialist Projects

Since the beginning of the space age, the goal of materials development in the aerospace industry has been to replace metal alloys with much lighter polymer resins, while maintaining the strength over a wide temperature range characteristic of metals. Polymers such as polyimides and epoxies have been used to satisfy many needs, but strength, temperature resistance, and ease of processing are difficult to incorporate into a single polymer. Because of this gap, bismaleimides and cyanate esters, and possibly combinations of the two, are seen as having potential in applications where ease of processing characteristic of epoxies is desired, but for …


H-1 Nuclear Magnetic Resonance Spin-Lattice Relaxation, C-13 Magic-Angle-Spinning Nuclear Magnetic Resonance Spectroscopy, Differential Scanning Calorimetry, And X-Ray Diffraction Of Two Polymorphs Of 2,6-Di-Tert-Butylnaphthalene, Peter A. Beckmann, Kendra S. Burbank, Katharine M. Clemo, Erin N. Slonaker, Kristin Averill, Cecil Dybowski, Joshua S. Figueroa, Alicia Glatfelter, Stephanie Koch, Louise M. Liable-Sands, Arnold L. Rheingold Aug 2000

H-1 Nuclear Magnetic Resonance Spin-Lattice Relaxation, C-13 Magic-Angle-Spinning Nuclear Magnetic Resonance Spectroscopy, Differential Scanning Calorimetry, And X-Ray Diffraction Of Two Polymorphs Of 2,6-Di-Tert-Butylnaphthalene, Peter A. Beckmann, Kendra S. Burbank, Katharine M. Clemo, Erin N. Slonaker, Kristin Averill, Cecil Dybowski, Joshua S. Figueroa, Alicia Glatfelter, Stephanie Koch, Louise M. Liable-Sands, Arnold L. Rheingold

Physics Faculty Research and Scholarship

Polymorphism, the presence of structurally distinct solid phases of the same chemical species, affords a unique opportunity to evaluate the structural consequences of intermolecular forces. The study of two polymorphs of 2,6-di-tert-butylnaphthalene by single-crystal x-ray diffraction, differential scanning calorimetry (DSC), C-13 magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and H-1 NMR spin-lattice relaxation provides a picture of the differences in structure and dynamics in these materials. The subtle differences in structure, observed with x-ray diffraction and chemical shifts, strikingly affect the dynamics, as reflected in the relaxation measurements. We analyze the dynamics in terms of both discrete sums and continuous …


Characterization Of An Isolate That Uses Vinyl Chloride As A Growth Substrate Under Aerobic Conditions, Matthew F. Verce, Ricky L. Ulrich, David L. Freedman Aug 2000

Characterization Of An Isolate That Uses Vinyl Chloride As A Growth Substrate Under Aerobic Conditions, Matthew F. Verce, Ricky L. Ulrich, David L. Freedman

Publications

An aerobic enrichment culture was developed by using vinyl chloride (VC) as the sole organic carbon and electron donor source. VC concentrations as high as 7.3 mM were biodegraded without apparent inhibition. VC use did not occur when nitrate was provided as the electron acceptor. A gram-negative, rod-shaped, motile isolate was obtained from the enrichment culture and identified based on biochemical characteristics and the sequence of its 16S rRNA gene as Pseudomonas aeruginosa, designated strain MF1. The observed yield of MF1 when it was grown on VC was 0.20 mg of total suspended solids (TSS)/mg of VC. Ethene, acetate, glyoxylate, …


Image-Based Change Detection Using An Integrated Spatiotemporal Gazetteer, Georgios Mountrakis Aug 2000

Image-Based Change Detection Using An Integrated Spatiotemporal Gazetteer, Georgios Mountrakis

Electronic Theses and Dissertations

This thesis addresses image-based change detection. Motivation was provided by the lack of algorithms that incorporate in their solution diverse types of pre-existing and complementary information and have the ability to interact with a spatiotemporal environment. The main differentiation with our approach is that we develop our algorithm within an integrated spatiotemporal environment and we make use of all change evidence that might exist within that environment. In addition, a change resolution model is developed that will distinguish meaningful changes based on user requirements. A model for change is proposed that establishes a general framework for the incorporation of image …


Reaction Of Caffeic Acid With Amino Acids, Yonggang Wang Aug 2000

Reaction Of Caffeic Acid With Amino Acids, Yonggang Wang

Masters Theses

The reaction of caffeic acid with tryptophan was studied as a model for the reaction of caffeic acid with amino acids in the aquatic environment. Although the autoxidation reaction of caffeic acid in aqueous solution with subsequent dimerization had been previously studied, it was examined as well for comparison purposes. The present studies demonstrate that oxidized caffeic acid would react with tryptophan. The reaction, like the dimerization reaction, was catalyzed by the presence of iron(III) ions at low pH ( <4) and by hydroxide ions at high pH (10). The reaction of caffeic acid with itself yielded six products, four of which were identified by mass spectroscopy as dimers, with the other two being trimers. The reaction of caffeic acid with tryptophan yielded three product peaks. Two of the product peaks had similar retention times to the dimers from the self-reaction of caffeic acid; the third was a new product resulting from the reaction of caffeic acid with the tryptophan.

A mechanism for the reaction of caffeic acid with tryptophan has been proposed. This mechanism was based on the analysis …


Studies Of Sulfur Reduction Of Taurine And Taurine-Conjugated Bile Acids By Bile Acid 7Α-Dehydroxylating Bacteria, Jiang Qian Aug 2000

Studies Of Sulfur Reduction Of Taurine And Taurine-Conjugated Bile Acids By Bile Acid 7Α-Dehydroxylating Bacteria, Jiang Qian

Masters Theses & Specialist Projects

Bile acids are C24 steroids that are derived in the liver from cholesterol and secreted into the intestinal lumen to aid in emulsification of dietary lipids and lipid-soluble vitamins. The indigenous intestinal microflora modify bile acids, producing up to 20 unique bile acid metabolites. The 7α-dehydroxylation of the bile acids is the most physiologically important bile acid biotransformation. All known intestinal bacteria capable of bile acid 7α-dehydroxylation are anaerobic, gram-positive rods of the genera Clostridium and Eubcicterium. Bile acid 7α-dehydroxylating bacteria often contain bile salt hydrolase, which hydrolyzes the peptide bond in taurine-conjugated bile acids to yield a free bile …


Study Of Polyaromatic Hydrocarbons Emitted In The Fly Ash From Coal Combustion In A Fluidized Bed Combuster, Rebecca Heltsley Aug 2000

Study Of Polyaromatic Hydrocarbons Emitted In The Fly Ash From Coal Combustion In A Fluidized Bed Combuster, Rebecca Heltsley

Masters Theses & Specialist Projects

Exposure to Polyaromatic Hydrocarbons (PAHs) has long been identified as an environmental concern because of their carcinogenic and mutagenic effects. The Environmental Protection Agency (EPA) has developed a list of 16 PAHs that are found on the Priority Pollutant List due to the extensive amount of data suggesting the hazards of these compounds. These toxic compounds are often emitted into the atmosphere by anthropogenic sources, such as combustors. Therefore, analysis of these compounds must be conducted during coal combustion. Two 1000-hour coal combustion burns were performed using the 0.1 MWth bench-scale fluidized bed combustor (FBC), which is found in the …


Kinetic Studies On The Reaction Of Hydroxyl Radicals With Aromatic Compounds, Paul Chadwick Aug 2000

Kinetic Studies On The Reaction Of Hydroxyl Radicals With Aromatic Compounds, Paul Chadwick

Masters

No abstract provided


Telemip: Telecommunications-Enhanced Mobile Ip Architecture For Fast Intradomain Mobility, Subir Das, Archan Misra, Prathima Agrawal, Sajal K. Das Aug 2000

Telemip: Telecommunications-Enhanced Mobile Ip Architecture For Fast Intradomain Mobility, Subir Das, Archan Misra, Prathima Agrawal, Sajal K. Das

Research Collection School Of Computing and Information Systems

This article first surveys existing protocols for supporting IP mobility and then proposes an extension to the mobile IP architecture, called TeleMIP. Our architecture attempts to achieve smaller handoff latency by localizing the scope of most location update messages within an administrative domain or a geographical region. TeleMIP is intended for use in evolving third-generation wireless networks, and introduces a new logical entity, called the mobility agent, which provides a mobile node with a stable point of attachment in a foreign network. While the MA is functionally similar to conventional foreign agents, it is located at a higher level in …


Rapidan River Watershed Riparian Restoration Assessment, Friends Of The Rappahannock, Center For Coastal Resources Management, Virginia Institute Of Marine Science Aug 2000

Rapidan River Watershed Riparian Restoration Assessment, Friends Of The Rappahannock, Center For Coastal Resources Management, Virginia Institute Of Marine Science

Reports

A canoe based GPS survey was conducted of 111 miles of the Rapidan River and its major tributaries. The purpose of the survey was to collect the necessary baseline data to support the prioritization of stream reaches in the Rapidan River watershed for future streambank and/or riparian corridor restoration projects.

The data were post-processed and overlaid onto digital color orthophoto quarter quad images at a scale of 1: 12,000 (resolution = 2 meters). Areas with critical erosion and/or riparian restoration needs were prioritized based on the analyzed features.


Environmental Survey Of Potential Sand Resource Sites, Offshore Delaware And Maryland : Final Report, Virginia Institute Of Marine Science Aug 2000

Environmental Survey Of Potential Sand Resource Sites, Offshore Delaware And Maryland : Final Report, Virginia Institute Of Marine Science

Reports

  • Technical summary / Carl H. Hobbs
  • Non-technical summary / Carl H. Hobbs
  • Part. 1. Benthic mapping and resource evaluation of potential sand mining areas, offshore Mayland and Delaware, 1998-1999 / G.R. Cutter and R.J. Diaz
  • Part. 2. Transitory species (vertebrate nekton) / John A. Musick
  • Part. 3. Literature survey of reproductive finfish and ichthyoplankton present in proposed sand mining locations within the Middle Atlantic Bight / John Olney, Donna Marie Bilkovic
  • Part. 4. Potential modifications to waves due to dredging and other oceanographic considerations / Jerome P.-Y. Maa, Sung C. Kim
  • Part. 5. Maryland-Delaware shoreline : long-term trends and short-term …


Alteration Processes Of Alkenones And Related Lipids In Water Columns And Sediments, H. Rodger Harvey Aug 2000

Alteration Processes Of Alkenones And Related Lipids In Water Columns And Sediments, H. Rodger Harvey

OES Faculty Publications

Alkenones produced by the haptophyte algae are currently being used as indices of sea surface temperature in recent and past ocean environments, but limited information is available concerning the impact of biotic and abiotic processes on the integrity of these long chain lipids. This synthesis provides selected background information on major alteration processes that must be considered before such indices can be used with confidence. A number of processes in the water column and surface sediments have the potential to impact the structural integrity of alkenones and compromise their ability as temperature markers. Processes discussed include the alteration of alkenone …


The Application And Performance Of A Generic Task Routine Decision Making Algorithm To Recipe Selection In Meal Planning, Michelle M. Cox Aug 2000

The Application And Performance Of A Generic Task Routine Decision Making Algorithm To Recipe Selection In Meal Planning, Michelle M. Cox

Theses and Dissertations - UTB/UTPA

A nutritional meal planning system was implemented to test the effectiveness of a previously developed routine decision making algorithm. The combinatorics involved in ordering recipes in all possible combinations to produce variability in a meal plan and provide sufficient nutrition is conceptually intensive. Meal planning involves selection of food to eat to fulfill a person's nutritional and personal preferences. This thesis demonstrates meal planning as a decision making problem and demonstrates the utility of the routine decision making algorithm by solving this problem. Generic Tasks, identified through artificial intelligence research, provides the basis for this algorithm. It uses user preferences …


Reducing Mass Degeneracy In Sar By Ms By Stable Isotopic Labeling, Chris Bailey-Kellogg, John J. Kelley Iii, Cliff Stein, Bruce Randall Donald Aug 2000

Reducing Mass Degeneracy In Sar By Ms By Stable Isotopic Labeling, Chris Bailey-Kellogg, John J. Kelley Iii, Cliff Stein, Bruce Randall Donald

Dartmouth Scholarship

Mass spectrometry (MS) promises to be an invaluable tool for functional genomics, by supporting low-cost, high-throughput experiments. However, large-scale MS faces the potential problem of mass degeneracy -- indistinguishable masses for multiple biopolymer fragments (e.g. from a limited proteolytic digest). This paper studies the tasks of planning and interpreting MS experiments that use selective isotopic labeling, thereby substantially reducing potential mass degeneracy. Our algorithms support an experimental-computational protocol called Structure-Activity Relation by Mass Spectrometry (SAR by MS), for elucidating the function of protein-DNA and protein-protein complexes. SAR by MS enzymatically cleaves a crosslinked complex and analyzes the resulting mass spectrum …


Design And Characterization Of A Synthetic Electron-Transfer Protein, Anna Y. Kornilova, James F. Wishart, Wenzhong Xiao, Robin C. Lasey, Anna Fedorova, Yeon-Kyun Shin, Michael Y. Ogawa Aug 2000

Design And Characterization Of A Synthetic Electron-Transfer Protein, Anna Y. Kornilova, James F. Wishart, Wenzhong Xiao, Robin C. Lasey, Anna Fedorova, Yeon-Kyun Shin, Michael Y. Ogawa

Chemistry Faculty Publications

A 30-residue polypeptide [H21(30-mer)] with the sequence Ac-K(IEALEGK)(2)(IEALEHK)-(IEALEGK)G-NH2 was synthesized. The circular dichroism (CD) spectrum of the peptide shows minima at 208 and 222 nm and theta(222)/theta(208) = 1.06, which indicates the formation of a self-assembled coiled-coil when dissolved in aqueous solution. The concentration dependence of the CD data can be fit to an expression that describes a two-state monomer-dimer equilibrium for the apopeptide (K-d = 1.5 +/- 0.4 mu M and theta(max) = -23 800 +/- 130 deg cm(2) dmol(-1)), showing that it has a maximum helicity of 69%. A [MTSL-C21(30-mer)] dimer was also prepared in which MTSL is …


Masses For Galactic Beat Cepheids, Noella L. D'Cruz, Siobahn M. Morgan, Erika Böhm-Vitense Aug 2000

Masses For Galactic Beat Cepheids, Noella L. D'Cruz, Siobahn M. Morgan, Erika Böhm-Vitense

Faculty Publications

Accurate mass determinations for Cepheids may be used to determine the degree of excess mixing in the interiors of their main-sequence progenitors : the larger the excess mixing, the larger the luminosity of the Cepheid of a given mass, or the smaller the mass of a Cepheid with given luminosity. Dynamical masses determined recently for a few Cepheid binaries indicate excess mixing somewhat stronger than that corresponding to the convective overshoot models by Schaller et al. Beat Cepheids can be used similarly to test main-sequence mixing in stellar interiors. The period ratios for beat Cepheids depend on luminosity, heavy element …


Is Overexcitability A Differential Personality Attribute Of High-Iq Youth? A Comparison Study Of Identified Gifted And Vocational High School Teenagers Using The Overexcitability Questionnaire (Oeq), Jane Piirto, Lori Beach, Geri Cassone, Robbin Rogers, John Fraas Jul 2000

Is Overexcitability A Differential Personality Attribute Of High-Iq Youth? A Comparison Study Of Identified Gifted And Vocational High School Teenagers Using The Overexcitability Questionnaire (Oeq), Jane Piirto, Lori Beach, Geri Cassone, Robbin Rogers, John Fraas

John W. Fraas

No abstract provided.


On The Effect Of Long-Wavelength Electron Plasma Waves On Large-Angle Stimulated Raman Scattering Of Short Laser Pulse In Plasmas, Nikolai E. Andreev, Serguei Y. Kalmykov Jul 2000

On The Effect Of Long-Wavelength Electron Plasma Waves On Large-Angle Stimulated Raman Scattering Of Short Laser Pulse In Plasmas, Nikolai E. Andreev, Serguei Y. Kalmykov

Serge Youri Kalmykov

Spectral features of a large-angle stimulated Raman scattering (LA SRS) of a short electromagnetic pulse in an underdense plasma, which are caused by the presence in a plasma of a given linear long-wavelength electron plasma wave (LW EPW), are investigated. It is shown that the LW EPW, whose phase velocity coincides with a group velocity of a pulse and a density perturbation normalized to a background electron density, \delta n_{LW} / n_0, exceeds the ratio of the electron plasma frequency to the laser frequency, \omega_{pe} / \omega_0, suppresses the well-known Stokes branch of the weakly coupled LA SRS. Under the …


Adapting To The Information Age, Jens G. Pohl Jul 2000

Adapting To The Information Age, Jens G. Pohl

Collaborative Agent Design (CAD) Research Center

This paper draws attention to the profound changes that human civilization is experiencing as it moves from an industrial environment into an information environment, in which unprecedented emphasis is placed on the knowledge and capabilities of the individual. A clear distinction is drawn between data and information in relationship to computer-based facilities, and the transition of data-processing to the higher levels of information and knowledge representation in quasi intelligent decision-support systems. It is argued that the cultivation of its human capital becomes a foundational requirement for the success of a knowledge-based organization. In such an organization traditional practices of hierarchical, …


An Inference Engine-Based Subscription Service, Kym J. Pohl, Jens G. Pohl Jul 2000

An Inference Engine-Based Subscription Service, Kym J. Pohl, Jens G. Pohl

Collaborative Agent Design (CAD) Research Center

A Distributed Network Architecture (DNA) forms the basis of many decision-support systems available today. Such architecture excels at providing an application environment rich in transparency, performance, and expandability (Gray and Lievano 1997). However, efforts at the Collaborative Agent Design (CAD) Research Center in San Luis Obispo, California have found that for this architecture to be successfully applied to agent-based, decision-support systems two additional ingredients must be present, namely a query service and a subscription service. These two mechanisms support the extensive collaboration inherent in agent-based, decision-support systems. Although primarily utilized as a means of agent-to-agent interaction these two services can …


Mechanical Mouse Lure For Brown Treesnakes, Alexandria C. Lindberg, John A. Shivik, Larry Clark Jul 2000

Mechanical Mouse Lure For Brown Treesnakes, Alexandria C. Lindberg, John A. Shivik, Larry Clark

United States Department of Agriculture Wildlife Services: Staff Publications

The importance of prey movement for stimulating feeding behavior of Brown Treesnakes was tested by using a mechanical mouse model in combination with and without prey odor. Prey movement was found to be important in stimulating brown treesnake feeding behavior. Prey movement combined with prey odor was not significantly different than prey movement alone. In the development of simple artificial lures based on the stimulus of live mice, visual lures lacking movement are likely to be ineffective. Lures that combine a visual moving stimulus with prey odor are likely to be the most effective artificial lure for trapping brown treesnakes.


Pesticide Waste Incineration In The Wet Process Cement Kiln, Marian Mazur, Robert Oleniacz, Marek Bogacki, Stanisław Słupek Jul 2000

Pesticide Waste Incineration In The Wet Process Cement Kiln, Marian Mazur, Robert Oleniacz, Marek Bogacki, Stanisław Słupek

Robert Oleniacz

The presentation discusses the problem of pesticide wastes in Poland that have been accumulated underground in concrete graveyards or bunkers. Their progressive unsealing poses a significant health risk to people due to groundwater, soil and air pollution. There are not many of professional hazardous waste incineration plants in Poland, therefore, the paper proposes the use of cement kiln for thermal treatment of such waste. Polish cement industry is interested in utilization of various wastes (e.g. in the capacity of alternative fuels) in the process connected with the cement clinker production in rotary kilns. High temperatures existing in cement kilns (ca. …


42nd Rocky Mountain Conference On Analytical Chemistry Jul 2000

42nd Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Abstracts from the 42nd annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Broomfield, Colorado, July 30 - August 3, 2000.


Driven Vortices In Confined Geometry: The Corbino Disk, M. Cristina Marchetti Jul 2000

Driven Vortices In Confined Geometry: The Corbino Disk, M. Cristina Marchetti

Physics - All Scholarship

The fabrication of artificial pinning structures allows a new generation of experiments which can probe the properties of vortex arrays by forcing them to flow in confined geometries. We discuss the theoretical analysis of such experiments in both flux liquids and flux solids, focusing on the Corbino disk geometry. In the liquid, these experiments can probe the critical behavior near a continuous liquid-glass transition. In the solid, they probe directly the onset of plasticity.


Final Quantum Nf State Analysis For Multiply Charged Ion-Circular Rydberg Target Collisions, K. R. Cornelius, Ronald E. Olson Jul 2000

Final Quantum Nf State Analysis For Multiply Charged Ion-Circular Rydberg Target Collisions, K. R. Cornelius, Ronald E. Olson

Physics Faculty Research & Creative Works

The classical trajectory Monte Carlo method has been used to simulate fully stripped ion-circular Rydberg atom collisions. We report that the mechanisms that govern the capture process for ions colliding with aligned Rydberg targets, namely direct and indirect velocity matching, alternate as to which is dominant. Previous experimental and theoretical results for singly charged ion-Rydberg atom collisions demonstrate that direct capture processes dominate at intermediate collision speeds. We have found that for highly charged ion-Rydberg atom collisions electron capture via indirect velocity matching is dominant at intermediate collision speeds and contributes up to 90% of the total capture cross-section.


Trajectory Mapping: A Tool For Validation Of Trace Gas Observations, Gary A. Morris, James F. Gleason, Jerald Ziemke, Mark R. Schoeberl Jul 2000

Trajectory Mapping: A Tool For Validation Of Trace Gas Observations, Gary A. Morris, James F. Gleason, Jerald Ziemke, Mark R. Schoeberl

Physics and Astronomy Faculty Publications

We investigate the effectiveness of trajectory mapping(TM) as a data validation tool. TM combines a dynamical model of the atmosphere with trace gas observations to provide more statistically robust estimates of instrument performance over much broader geographic areas than traditional techniques are able to provide. We present four detailed case studies selected so that the traditional techniques are expected to work well. In each case the TM results are equivalent to or improve upon the measurement comparisons performed with traditional approaches. The TM results are statistically more robust than those achieved using traditional approaches since the TM comparisons occur over …


Rescaling The Energy Function In Hopfield Networks, Tony R. Martinez, Xinchuan Zeng Jul 2000

Rescaling The Energy Function In Hopfield Networks, Tony R. Martinez, Xinchuan Zeng

Faculty Publications

In this paper we propose an approach that rescales the distance matrix of the energy function in the Hopfield network for solving optimization problems. We rescale the distance matrix by normalizing each row in the matrix and then adjusting the parameter for the distance term. This scheme has the capability of reducing the effects of clustering in data distributions, which is one of main reasons for the formation of invalid solutions. We evaluate this approach through a large number (20,000) simulations based on 200 randomly generated city distributions of the 10-city traveling salesman problem. The result shows that, compared to …


The Inefficiency Of Batch Training For Large Training Sets, Tony R. Martinez, D. Randall Wilson Jul 2000

The Inefficiency Of Batch Training For Large Training Sets, Tony R. Martinez, D. Randall Wilson

Faculty Publications

Multilayer perceptrons are often trained using error backpropagation (BP). BP training can be done in either a batch or continuous manner. Claims have frequently been made that batch training is faster and/or more "correct" than continuous training because it uses a better approximation of the true gradient for its weight updates. These claims are often supported by empirical evidence on very small data sets. These claims are untrue, however, for large training sets. This paper explains why batch training is much slower than continuous training for large training sets. Various levels of semi-batch training used on a 20,000-instance speech recognition …


Energetics And Geometry Of Excitations In Random Systems, Alan Middleton Jul 2000

Energetics And Geometry Of Excitations In Random Systems, Alan Middleton

Physics - All Scholarship

Methods for studying droplets in models with quenched disorder are critically examined. Low energy excitations in two dimensional models are investigated by finding minimal energy interior excitations and by computing the effect of bulk perturbations. The numerical data support the assumptions of compact droplets and a single exponent for droplet energy scaling. Analytic calculations show how strong corrections to power laws can result when samples and droplets are averaged over. Such corrections can explain apparent discrepancies in several previous numerical results for spin glasses