Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

2003

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 2551 - 2580 of 3876

Full-Text Articles in Physical Sciences and Mathematics

Phase Retrieval Using A Genetic Algorithm On The Systematic Image-Based Optical Alignment Test Bed, Jaime R. Taylor Jan 2003

Phase Retrieval Using A Genetic Algorithm On The Systematic Image-Based Optical Alignment Test Bed, Jaime R. Taylor

Physics Faculty Research

NASA’s Marshall Space Flight Center’s Systematic Image-Based Optical Alignment (SIBOA) Testbed was developed to test phase retrieval algorithms and hardware techniques. Individuals working with the facility developed the idea of implementing phase retrieval by breaking the determination of the tip/tilt of each mirror apart from the piston motion (or translation) of each mirror. Presented in this report is an algorithm that determines the optimal phase correction associated only with the piston motion of the mirrors.

Go to article

Inverted Velocity Profile In The Cylindrical Couette Flow Of A Rarefied Gas, Alejandro Garcia, K. Aoki, H. Yoshida, T. Nakanishi Jan 2003

Inverted Velocity Profile In The Cylindrical Couette Flow Of A Rarefied Gas, Alejandro Garcia, K. Aoki, H. Yoshida, T. Nakanishi

Faculty Publications

The cylindrical Couette flow of a rarefied gas is investigated, under the diffuse-specular reflection condition of Maxwell’s type on the cylinders, in the case where the inner cylinder is rotating whereas the outer cylinder is at rest. The inverted velocity profile for small accommodation coefficients, pointed out by Tibbs, Baras, and Garcia [Phys. Rev. E 56, 2282 (1997)] on the basis of a Monte Carlo simulation, is investigated extensively by means of a systematic asymptotic analysis for small Knudsen numbers as well as the direct numerical analysis of the Boltzmann equation, and the parameter range in which the phenomenon appears …

Go to article

A Direct Simulation Monte Carlo Method For The Uehling-Uhlenbeck-Boltzmann Equation, Alejandro Garcia, W. Wagner Jan 2003

A Direct Simulation Monte Carlo Method For The Uehling-Uhlenbeck-Boltzmann Equation, Alejandro Garcia, W. Wagner

Faculty Publications

In this paper we describe a direct simulation Monte Carlo algorithm for the Uehling-Uhlenbeck-Boltzmann equation in terms of Markov processes. This provides a unifying framework for both the classical Boltzmann case as well as the Fermi-Dirac and Bose-Einstein cases. We establish the foundation of the algorithm by demonstrating its link to the kinetic equation. By numerical experiments we study its sensitivity to the number of simulation particles and to the discretization of the velocity space, when approximating the steady-state distribution.

Go to article

Tracing The Star Stream Through M31 Using Planetary Nebula Kinematics, H. R. Merrett, K. Kuijken, M. R. Merrifield, Aaron J. Romanowsky, N. G. Douglas, N. R. Napolitano, M. Arnaboldi, M. Capaccioli, K. C. Freeman, O. Gerhard, N. W. Evans, M. I. Wilkinson, C. Halliday, T. J. Bridges, D. Carter Jan 2003

Tracing The Star Stream Through M31 Using Planetary Nebula Kinematics, H. R. Merrett, K. Kuijken, M. R. Merrifield, Aaron J. Romanowsky, N. G. Douglas, N. R. Napolitano, M. Arnaboldi, M. Capaccioli, K. C. Freeman, O. Gerhard, N. W. Evans, M. I. Wilkinson, C. Halliday, T. J. Bridges, D. Carter

Faculty Publications

We present a possible orbit for the Southern Stream of stars in M31, which connects it to the Northern Spur. Support for this model comes from the dynamics of planetary nebulae (PNe) in the disc of M31: analysis of a new sample of 2611 PNe obtained using the Planetary Nebula Spectrograph reveals ∼20 objects with kinematics inconsistent with the normal components of the galaxy, but which lie at the right positions and velocities to connect the two photometric features via this orbit. The satellite galaxy M32 is coincident with the stream both in position and velocity, adding weight to the …

Go to article

A Dearth Of Dark Matter In Ordinary Elliptical Galaxies, Aaron J. Romanowsky, N. G. Douglas, M. Arnaboldi, K. Kuijken, M. R. Merrifield, N. R. Napolitano, M. Capaccioli Jan 2003

A Dearth Of Dark Matter In Ordinary Elliptical Galaxies, Aaron J. Romanowsky, N. G. Douglas, M. Arnaboldi, K. Kuijken, M. R. Merrifield, N. R. Napolitano, M. Capaccioli

Faculty Publications

The kinematics of the outer parts of three intermediate-luminosity elliptical galaxies were studied with the Planetary Nebula Spectrograph. The galaxies' velocity-dispersion profiles were found to decline with the radius, and dynamical modeling of the data indicates the presence of little if any dark matter in these galaxies' halos. This unexpected result conflicts with findings in other galaxy types and poses a challenge to current galaxy formation theories.

Go to article

Privacy-Preserving Collaborative Filtering Using Randomized Perturbation Techniques, Huseyin Polat, Wenliang Du Jan 2003

Privacy-Preserving Collaborative Filtering Using Randomized Perturbation Techniques, Huseyin Polat, Wenliang Du

Electrical Engineering and Computer Science - All Scholarship

Collaborative Filtering (CF) techniques are becoming increasingly popular with the evolution of the Internet. E-commerce sites use CF systems to suggest products to customers based on like-minded customers' preferences. People use CF systems to cope with information overload. To conduct collaborative filtering, data from customers are needed. However, collecting high quality data from customers is not an easy task because many customers are so concerned about their privacy that they might decide to give false information. CF systems using these data might produce inaccurate recommendations. We propose a randomized perturbation technique to protect users' privacy while still producing accurate recommendations. …

Go to article

Interacting Data Services For Distributed Earthquake Modeling, Marlon Pierce, Choonhan Youn, Geoffrey C. Fox Jan 2003

Interacting Data Services For Distributed Earthquake Modeling, Marlon Pierce, Choonhan Youn, Geoffrey C. Fox

Electrical Engineering and Computer Science - All Scholarship

We present XML schemas and our design for related data services for describing faults and surface displacements, which we use within earthquake modeling codes. These data services are implemented using a Web services approach and are incorporated in a portal architecture with other, general purpose services for application and file management. We make use of many Web services standards, including WSDL and SOAP, with specific implementations in Java. We illustrate how these data models and services may be used to build distributed, interacting applications through data flow.

Go to article

Balancing The Performance Of A Sensor Network Using An Ant System, Rajani Muraleedharan, Lisa Ann Osadciw Jan 2003

Balancing The Performance Of A Sensor Network Using An Ant System, Rajani Muraleedharan, Lisa Ann Osadciw

Electrical Engineering and Computer Science - All Scholarship

In a sensor network consisting of both wired and wireless links, the nodes sense, collect and distribute dynamic information from one sensor to the other. Energy consumption is a key issue in the sensor’s communications since many use battery power, which is limited. The sensors also have limited memory and functionality to support communications. Therefore, there is a need to balance energy usage with obtaining the shortest communication distance. This paper presents a novel approach to selecting message routes using an ant system. Parameters controlling the convergence of the ant system are analyzed in terms of wired and wireless networks.

Go to article

A Transport Framework For Distributed Brokering Systems, Shrideep Pallickara, Geoffrey C. Fox, John Yin, Gurham Gunduz, Hongbin Liu, Ahmet Uyar, Mustafa Varank Jan 2003

A Transport Framework For Distributed Brokering Systems, Shrideep Pallickara, Geoffrey C. Fox, John Yin, Gurham Gunduz, Hongbin Liu, Ahmet Uyar, Mustafa Varank

Electrical Engineering and Computer Science - All Scholarship

Increasingly, services need to interact with a wide spectrum of devices with varying networking capabilities. Services hosted on a messaging infrastructure need to optimally utilize and exploit the conditions that exist within the local networks. The messaging infrastructure must manage the communication between external resources, services and clients to achieve the highest possible system performance and reliability. In this paper we suggest that a transport framework needs to be incorporated into the messaging infrastructure hosting the services. We base our investigations in the context of the NaradaBrokering system.

Go to article

Building Problem Solving Environments With Application Web Service Toolkits, Choonhan Youn, Marlon Pierce, Geoffrey C. Fox Jan 2003

Building Problem Solving Environments With Application Web Service Toolkits, Choonhan Youn, Marlon Pierce, Geoffrey C. Fox

Electrical Engineering and Computer Science - All Scholarship

Application portals, or Problem Solving Environments (PSEs), provide user environments that simplify access and integrate various distributed computational services for scientists working on particular classes of problems. Specific application portals are typically built on common sets of core services, so reusability of these services is a key problem in PSE development. In this paper we address the reusability problem by presenting a set of core services built using the Web services model and application metadata services that can be used to build science application front ends out of these core services.

Go to article

An Adaptive Qos Routing Protocol With Dispersity For Ad-Hoc Networks, Youngki Hwang, Pramod Varshney Jan 2003

An Adaptive Qos Routing Protocol With Dispersity For Ad-Hoc Networks, Youngki Hwang, Pramod Varshney

Electrical Engineering and Computer Science - All Scholarship

In this paper, we present the design and simulation of a bandwidth constrained multiple path on-demand routing protocol for ad-hoc networks to support end-to-end Quality of Service, which is known as the Adaptive Dispersity QoS Routing (ADQR) Protocol. We propose a route discovery algorithm to find multiple disjoint paths with longerlived connections, where each path also specifies associated network resource information. This provides an efficient approach for network resource reservation combined with data dispersion and for route maintenance. A longerlived path generally involves less route maintenance, resulting in an increase of bandwidth utilization. We propose a route maintenance algorithm to …

Go to article

Sensor Communication Networks Using Swarming Intelligence, Rajani Muraleedharan, Lisa Ann Osadciw Jan 2003

Sensor Communication Networks Using Swarming Intelligence, Rajani Muraleedharan, Lisa Ann Osadciw

Electrical Engineering and Computer Science - All Scholarship

Energy consumption is currently a key issue in research for future sensor networks. This paper presents a novel approach to sensor network routing based on energy consumption. The unique routing algorithm uses swarm intelligence, which is computationally efficient.

Go to article

An Intelligent Deployment And Clustering Algorithm For A Distributed Mobile Sensor Network, Nojeong Heo, Pramod K. Varshney Jan 2003

An Intelligent Deployment And Clustering Algorithm For A Distributed Mobile Sensor Network, Nojeong Heo, Pramod K. Varshney

Electrical Engineering and Computer Science - All Scholarship

Energy in a wireless sensor network(WSN) is a precious resource. Deployment of mobile sensors in a WSN is an energy consuming process and it should be carefully designed. In this paper, we propose an intelligent energy-efficient deployment algorithm for cluster-based WSN by a synergistic combination of cluster structuring and a peer-to-peer deployment scheme. Performance of our algorithm is evaluated in terms of coverage, uniformity, and time and distance traveled till the algorithm converges. Our algorithm is shown to exhibit excellent performance.

Go to article

Optimization Using Particle Swarms With Near Neighbor Interactions, Kalyan Veeramachaneni, Thanmaya Peram, Chilukuri K. Mohan, Lisa Ann Osadciw Jan 2003

Optimization Using Particle Swarms With Near Neighbor Interactions, Kalyan Veeramachaneni, Thanmaya Peram, Chilukuri K. Mohan, Lisa Ann Osadciw

Electrical Engineering and Computer Science - All Scholarship

This paper presents a modification of the particle swarm optimization algorithm (PSO) intended to combat the problem of premature convergence observed in many applications of PSO. In the new algorithm, each particle is attracted towards the best previous positions visited by its neighbors, in addition to the other aspects of particle dynamics in PSO. This is accomplished by using the ratio of the relative fitness and the distance of other particles to determine the direction in which each component of the particle position needs to be changed. The resulting algorithm, known as Fitness-Distance-Ratio based PSO (FDR-PSO), is shown to perform …

Go to article

An Integrated Videoconferencing System For Heterogeneous Multimedia Collaboration, Ahmet Uyar, Wenjun Wu, Hasan Bulut, Geoffrey C. Fox Jan 2003

An Integrated Videoconferencing System For Heterogeneous Multimedia Collaboration, Ahmet Uyar, Wenjun Wu, Hasan Bulut, Geoffrey C. Fox

Electrical Engineering and Computer Science - All Scholarship

We have developed an integrated conferencing system, Global Multimedia Collaboration System, which enables heterogeneous multimedia clients to join the same real-time sessions. Our system provides support for a variety of protocols and applications, including H.323 clients, SIP clients and Access Grid rooms. In this paper, we would like to show the features and design principles of our conferencing server which facilitates audio and video communications among participating clients in a real-time conference.

Go to article

Mutual Information Based Image Registration For Remote Sensing Data, Hua-Mei Chen, Manoj K. Arora, Pramod K. Varshney Jan 2003

Mutual Information Based Image Registration For Remote Sensing Data, Hua-Mei Chen, Manoj K. Arora, Pramod K. Varshney

Electrical Engineering and Computer Science - All Scholarship

Registration is a fundamental operation in image processing to align images taken at different times, from different sensors or from different viewing angles. Automatic image registration procedures are gaining importance to efficiently register large volumes of remote sensing data available these days. In this Letter, we investigate an automated mutual information based registration technique for remote sensing data. Performance of a number of interpolation algorithms to compute mutual information for registration of multi-sensor and multi-resolution Landsat TM, Radarsat SAR and IRS PAN images is evaluated.

Go to article

Peer-To-Peer Grids, Geoffrey C. Fox, Dennis Gannon, Sung-Hoon Ko, Shrideep Pallickara, Xiaohong Qiu, Ahmet Uyar Jan 2003

Peer-To-Peer Grids, Geoffrey C. Fox, Dennis Gannon, Sung-Hoon Ko, Shrideep Pallickara, Xiaohong Qiu, Ahmet Uyar

Electrical Engineering and Computer Science - All Scholarship

We describe Peer-to-Peer Grids built around Integration of technologies from the peer-to-peer and Grid fields. We focus on the role of Web services linked by a powerful event service using uniform XML interfaces and application level routing. We describe how a rich synchronous and asynchronous collaboration environment can support virtual communities built on top of such infrastructure. Universal access mechanisms are discussed.

Go to article

Estimating Watershed Biodiversity: An Empirical Study Of The Chesapeake Bay In Maryland, Usa, Junko Morimoto, Helena Voinov, Matthew A. Wilson, Robert Costanza Jan 2003

Estimating Watershed Biodiversity: An Empirical Study Of The Chesapeake Bay In Maryland, Usa, Junko Morimoto, Helena Voinov, Matthew A. Wilson, Robert Costanza

Institute for Sustainable Solutions Publications and Presentations

There has been increasing demand for rigorous methods for evaluating biodiversity, one of the ecosystem services that sustains and fulfills human life. After carefully examining the literature, we found three key points that should be taken into account when we evaluate biodiversity. The first point is that any "indicator species" tends to be a leaky target of biodiversity. The second point is that "buffering" that is useful for representing the ecological concept of boundaries should have scientific meanings. The third point is that a "watershed" that integrates most natural processes is advantageous as the spatial range for evaluation. Based on …

Go to article

A Gentle Introduction To (Or Review Of) Fundamentals Of Chemistry And Organic Chemistry, Dan E. Krane, Michael L. Raymer Jan 2003

A Gentle Introduction To (Or Review Of) Fundamentals Of Chemistry And Organic Chemistry, Dan E. Krane, Michael L. Raymer

Computer Science and Engineering Faculty Publications

Presentation prepared for CS 790: Bioinformatics. The lecture comprises material from the text Fundamental Concepts of Bioinformatics.

Go to article

Sequence Alignments And Database Searches, Dan E. Krane, Michael L. Raymer Jan 2003

Sequence Alignments And Database Searches, Dan E. Krane, Michael L. Raymer

Computer Science and Engineering Faculty Publications

Presentation prepared for Intro to Bioinformatics. The lecture comprises material from the text Fundamental Concepts of Bioinformatics.

Go to article

Analyzing Algorithms & Asymptotic Notation, Dan E. Krane, Michael L. Raymer Jan 2003

Analyzing Algorithms & Asymptotic Notation, Dan E. Krane, Michael L. Raymer

Computer Science and Engineering Faculty Publications

Presentation prepared for BIO/CS 471: Algorithms for Bioinformatics. The lecture comprises material from the text Fundamental Concepts of Bioinformatics.

Go to article

The Structure And Functions Of Proteins, Dan E. Krane, Michael L. Raymer Jan 2003

The Structure And Functions Of Proteins, Dan E. Krane, Michael L. Raymer

Computer Science and Engineering Faculty Publications

Presentation prepared for BIO 271/CS 399: Bioinformatics. The lecture comprises material from the text Fundamental Concepts of Bioinformatics.

Go to article

A Continuation Of The Discussion On Cross Symmetry Of Solutions, Paul W. Eloe, Qin Sheng Jan 2003

A Continuation Of The Discussion On Cross Symmetry Of Solutions, Paul W. Eloe, Qin Sheng

Mathematics Faculty Publications

In this paper we continue to explore cross-symmetry properties of the solutions of second-order nonlinear boundary value problems on time scales. Dynamic equations under delta and nabla differentiations are considered. It is proven that, by introducing a proper companion problem, the solution of a dynamic equation is cross-symmetric to the solution of the companion problem. Proper jump functions on time scales are utilized. Computational examples are given to further illustrate our conclusions.

Go to article

Generalized Geologic Map For Land-Use Planning: Woodford County, Kentucky, Daniel I. Carey, Martin C. Noger, Paul Howell Jan 2003

Generalized Geologic Map For Land-Use Planning: Woodford County, Kentucky, Daniel I. Carey, Martin C. Noger, Paul Howell

Map and Chart--KGS

This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic bedrock conditions that affect the selection of sites for various purposes. The properties of thick soils may supercede those of the underlying bedrock and should be considered on a site to site basis. At any site, it is important to understand both the soils, and the underlying rock.

Go to article

A First Course In Computer Science: Languages And Goals, Dennis C. Smolarski Jan 2003

A First Course In Computer Science: Languages And Goals, Dennis C. Smolarski

Mathematics and Computer Science

The College Board Advanced Placement exam in computer science will use the language Java starting in fall 2003. The language chosen for this exam is based on the language commonly taught in introductory computer science courses at the university level. This article reviews the purpose of an introductory course and the various suggestions for the curriculum of introductory courses published by the Association for Computing Machinery. It then proposes that such a course stress foundational concepts over specific language syntax, and then provides a list of such foundational concepts and related topics. Based on this fundamental curriculum, the article recommends …

Go to article

Fight On! A Thirty Year History Of The Sawmill Slough Conservation Club, Michael W. Woodward, Erin B. Wiggins Jan 2003

Fight On! A Thirty Year History Of The Sawmill Slough Conservation Club, Michael W. Woodward, Erin B. Wiggins

Conservation Club

A history of the Sawmill Slough Conservation Club from it's beginnings to 2003

Go to article

Cover - Table Of Contents Jan 2003

Cover - Table Of Contents

Journal of the Iowa Academy of Science: JIAS

No abstract provided.

Go to article

A Framework For Reproductive Models Of Mourning Doves, David L. Otis Jan 2003

A Framework For Reproductive Models Of Mourning Doves, David L. Otis

Journal of the Iowa Academy of Science: JIAS

Population models can be used to aid in development and evaluation of harvest management strategies for game species. No current models are available for the Mourning Dove (Zenaida macroura), which is considered a migratory game bird in 37 states. A predictive model for annual reproduction is a necessary component of such a model. I used a simple construct based on parameters of the Mourning Dove breeding cycle to develop probability distributions of annual per capita reproduction for each of five geographical regions in the U.S. Confidence intervals for model predictions included average estimates from published studies in all regions except …

Go to article

The Redox Potential Of Ddt: An Environmental Perspective, Anne Lewis, Christopher Cramer, John Bumpus Jan 2003

The Redox Potential Of Ddt: An Environmental Perspective, Anne Lewis, Christopher Cramer, John Bumpus

Presidential Scholars Theses (1990 – 2006)

Due to their low water solubility, the reduction potentials of DDT and dicofol are difficult to determine experimentally. Through computational methods, we calculated the one and two electron reduction potentials for DDT as 0.51 V and 0.67 V, respectively, and those for dicofol were 0.50 V and 0.74 V. This study is significant because we are able to calculate reliable redox potentials that may be utilized to predict chemical behavior and degradation pathways of environmental pollutants. To assess the accuracy of theoretical chemistry, we compared experimental and computational data and examined whether our calculated redox potentials fit with the known …

Go to article

Determination Of Iron(Ii) Concentrations In Seawater Using Flow Injection Analysis And Chemiluminescence, Mark Keller Kinnan Jan 2003

Determination Of Iron(Ii) Concentrations In Seawater Using Flow Injection Analysis And Chemiluminescence, Mark Keller Kinnan

All Volumes (2001-2008)

Phytoplankton are a major consumer of carbon dioxide. In theory, if phytoplankton are limited in number, more carbon dioxide will be present in the atmosphere and contribute to the greenhouse effect. An increased concentration of iron would, therefore, promote phytoplankton blooms that would consume carbon dioxide. There would then be less carbon dioxide in the atmosphere to prevent heat from radiating away from earth. In 1996, an iron seeding experiment was performed in the open ocean to determine whether phytoplankton density would be increased. Phytoplankton rapidly increased in number. The research project results suggested that iron seeding the polar oceans …

Go to article

First Prev Next Last