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1997

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Articles 1591 - 1620 of 2472

Full-Text Articles in Physical Sciences and Mathematics

Correlation Of Changes In The Outer-Zone Relativistic-Electron Population With Upstream Solar Wind Measurements, J B. Blake, D N. Baker, Niescja E. Turner, K Ogilvie, R P. Lepping Jan 1997

Correlation Of Changes In The Outer-Zone Relativistic-Electron Population With Upstream Solar Wind Measurements, J B. Blake, D N. Baker, Niescja E. Turner, K Ogilvie, R P. Lepping

Physics and Astronomy Faculty Research

A study has been made of the correlation of the population of relativistic electrons in the outer-zone magnetosphere with the properties of the solar wind (speed, density, magnetic field) during a solar minimum period. The study is based upon observations made in the Spring of 1995 with sensors aboard 1994-026 and WIND. It is found that a large relativistic electron enhancement depends upon a substantial solar-wind speed increase associated with precursor solar-wind density enhancement, and, in particular, upon a southward turning of the interplanetary magnetic field

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Mine Boundary Detection Using Partially Ordered Markov Models, Xia Hua, Jennifer Davidson, Noel A. Cressie Jan 1997

Mine Boundary Detection Using Partially Ordered Markov Models, Xia Hua, Jennifer Davidson, Noel A. Cressie

Faculty of Informatics - Papers (Archive)

Detection of objects in images in an automated fashion is necessary for many applications, including automated target recognition. In this paper, we present results of an automated boundary detection procedure using a new subclass of Markov random fields (MRFs), called partially ordered Markov models (POMMs). POMMs offer computational advantages over general MRFs. We show how a POMM can model the boundaries in an image. Our algorithm for boundary detection uses a Bayesian approach to build a posterior boundary model that locates edges of objects having a closed loop boundary. We apply our method to images of mines with very good …

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Models And Inference For Clustering Of Locations Of Mines And Minelike Objects, Noel A. Cressie, Andrew B. Lawson Jan 1997

Models And Inference For Clustering Of Locations Of Mines And Minelike Objects, Noel A. Cressie, Andrew B. Lawson

Faculty of Informatics - Papers (Archive)

Mines and mine-like objects are distributed throughout an area of interest. Remote sensing of the area form an aircraft yields image data that represent the superposition of electromagnetic emissions from the mines and mine-like objects. In this article we build a hierarchical statistical model for the reconstruction of mien locations given a point pattern of the superposition of mines and mine-like objects. It is shown how inference on the mine locations can be obtained using Markov chain Monte Carlo methods.

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On 4-Npaf(1,2w) Sequences, Marc Gysin, Jennifer Seberry Jan 1997

On 4-Npaf(1,2w) Sequences, Marc Gysin, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

We give an overview on the existence of 4-NPAF (1,2w) sequences. We sketch some construction methods which give new 4-NPAF(1,2w) sequences and new orthogonal designs OD(4n;1,2w).

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Weighing Matrices And Their Applications, Christos Koukouvinos, Jennifer Seberry Jan 1997

Weighing Matrices And Their Applications, Christos Koukouvinos, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Three major applications of weighing matrices are discussed. New weighing matrices and skew weighing matrices are given for many orders 4t ≤ 100. We resolve the skew-weighing matrix conjecture in the affirmative for 4t ≤ 88.

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How To Prevent Cheating In Pinch's Scheme, G. Hossein, J. Pieprzyk, G. Chaundhry, Jennifer Seberry Jan 1997

How To Prevent Cheating In Pinch's Scheme, G. Hossein, J. Pieprzyk, G. Chaundhry, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

A modified protocol is proposed which prevents cheating in the Online multiple secret sharing scheme proposed by Pinch.

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Optimal Designs, Supplementary Difference Sets And Multipliers, Christos Koukouvinos, Jennifer Seberry, A. L. Whiteman, Xia Ming-Yuan Jan 1997

Optimal Designs, Supplementary Difference Sets And Multipliers, Christos Koukouvinos, Jennifer Seberry, A. L. Whiteman, Xia Ming-Yuan

Faculty of Informatics - Papers (Archive)

We investigate multipliers of 2 - {v; q2, q2; λ} supplementary difference sets where cyclotomy has been used to construct D-optimal designs.

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Computer Viruses An Introduction, Jeffrey Horton, Jennifer Seberry Jan 1997

Computer Viruses An Introduction, Jeffrey Horton, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

Computer viruses pose a considerable problem for users of personal computers. The recent emergence of macro viruses as a problem of some importance may heighten virus awareness in general. Yet most people have little or no understanding of common anti-virus measures, the varieties of viruses that exist today, and the strategies which they use to accomplish infection and to defeat anti-viruses. It is well-known that the virus problem is most severe for users of IBM PCs and compatibles; however, users of other platforms, such as the Macintosh, should not become complacent - viruses exist for many platforms in varying numbers. …

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Application Of Visual Modelling In Image Restoration And Colour Image Processing, Aziz Qureshi, Philip Ogunbona Jan 1997

Application Of Visual Modelling In Image Restoration And Colour Image Processing, Aziz Qureshi, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

This paper describes the application of human visual models in (i) defining a visually uniform colour representation space and (ii) the formulation of visually weighted Kalman filtering for image restoration. The former being useful in colour image quantisation and compression. For (i), the uniformity of chromaticity differences at the ouptut of Frei ’s colour vision model [3] is tested and compensated for by using MacAdam’s uniform chromaticity space. For (ii), the dynamical image model of the Kalman filter is visually weighted using the frequency response of Stockham’s model [l] of human vision.

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Shape Vq-Based Adaptive Predictive Lossless Image Coder, Jiazhao Wang, Philip Ogunbona, Golshah Naghdy Jan 1997

Shape Vq-Based Adaptive Predictive Lossless Image Coder, Jiazhao Wang, Philip Ogunbona, Golshah Naghdy

Faculty of Informatics - Papers (Archive)

A new shape adaptive predictive lossless image coder is proposed. Three classes of block shapes are delineated with associated “optimum” predctors. Each image is partitioned into sub-blocks that are classified into one of the three classes using vector quantisation. The encoder then employs the predictor corresponding to the class of the block under consideration. Performance evaluation of the proposed coder in comparison with four other lossless coders includmg lossless JPEG indicates its superiority.

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On The Step Response Of The Dct, Jim Andrew, Philip Ogunbona Jan 1997

On The Step Response Of The Dct, Jim Andrew, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

We show that the discrete cosine transform (DCT) is the best orthogonal transform, in terms of energy packing efficiency, for coding input steps of uniformly distributed random phase. Over sufficiently small block sizes, edges in an image can be modeled as such step inputs. This characteristic of the DCT, coupled with its high energy packing efficiency for highly correlated data, helps explain the impressive performance of the DCT for image compression.

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Wavelet-Based Feature-Adaptive Adaptive Resonance Theory Neural Network For Texture Identification, Jiazhao Wang, Golshah Naghdy, Philip Ogunbona Jan 1997

Wavelet-Based Feature-Adaptive Adaptive Resonance Theory Neural Network For Texture Identification, Jiazhao Wang, Golshah Naghdy, Philip Ogunbona

Faculty of Informatics - Papers (Archive)

A new method of texture classification comprising two processing stages, namely a low-level evolutionary feature extraction based on Gabor wavelets and a high-level neural network based pattern recognition, is proposed. The design of these stages is motivated by the processes involved in the human visual system: low-level receptors responsible for early vision processing and the high-level cognition. Gabor wavelets are used as extractors of ‘‘lowlevel’’ features that feed the feature-adaptive adaptive resonance theory (ART) neural network acting as a high-level ‘‘cognitive system.’’ The novelty of the model developed in this paper lies in the use of a self-organizing input layer …

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Content-Based Retrieval From Compressed-Image Databases, Philip Ogunbona, P Sangassapaviriya Jan 1997

Content-Based Retrieval From Compressed-Image Databases, Philip Ogunbona, P Sangassapaviriya

Faculty of Informatics - Papers (Archive)

There is an enormous amount of multi-media data including images, video, speech, audio and text, distributed among the various computer nodes on the Internet. The extent to which a user wiU be able to derive useful information from these data depends largely on the ease with which required data can be retrieved from the databases. The share volume of the data also poses a storage constraint on the databases; hence these data will need to exist in the compressed form on the databases. In this paper we concentrate on image data and propose a new paradigm in which a compressed …

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Edge Image Description Using Fractal Interpolation, P Motallebi, P O. Ogunbona Jan 1997

Edge Image Description Using Fractal Interpolation, P Motallebi, P O. Ogunbona

Faculty of Informatics - Papers (Archive)

Edge images derived from compressed image databases are described using fractal techniques. The proposed method is able to give affine transformation-invariant description suitable for use in a query-by-example database application. Comparison among the proposed method, polynomial interpolation and spline interpolation is given. It is concluded that fractal interpolation can give a compact description of image contours and is able to cope with random perturbation of the coordinates of the contour points by as much as 25 percent.

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A Cause Of Chaos, R. Nillsen Jan 1997

A Cause Of Chaos, R. Nillsen

Faculty of Informatics - Papers (Archive)

An abstract dynamical system consists of a collection S of points together with a transformation, or function, f which maps points of S into points of S. The points in S stand for all possible states of the system. The transformation is a “process of change” over one time unit, that changes each state x in S into another state f(x). Then we can interpret the equation f(x)=y as meaning that if the system is in state x, over the next time unit it will change into the state y. Alternatively, x is a “cause” of y, or x is …

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Financial Prediction And Trading Strategies Using Neurofuzzy Approaches, K. N. Pantazopoulos, L. H. Tsoukalas, N. G. Bourbakis, M. J. Brün, Elias N. Houstis Jan 1997

Financial Prediction And Trading Strategies Using Neurofuzzy Approaches, K. N. Pantazopoulos, L. H. Tsoukalas, N. G. Bourbakis, M. J. Brün, Elias N. Houstis

Department of Computer Science Technical Reports

No abstract provided.

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Computing Volumes Of Solids Enclosed By Recursive Subdivision Surfaces, Jörg Peters, Ahmad Nasri Jan 1997

Computing Volumes Of Solids Enclosed By Recursive Subdivision Surfaces, Jörg Peters, Ahmad Nasri

Department of Computer Science Technical Reports

No abstract provided.

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Future Scientific Software Systems, John R. Rice Jan 1997

Future Scientific Software Systems, John R. Rice

Department of Computer Science Technical Reports

No abstract provided.

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Videotext Database System, Haitao Jiang, Danilo Montesi, Ahmed K. Elmagarmid Jan 1997

Videotext Database System, Haitao Jiang, Danilo Montesi, Ahmed K. Elmagarmid

Department of Computer Science Technical Reports

No abstract provided.

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Computing Moments Of Piecewise Polynomial Surfaces, Carlos Gonzalez-Ochoa, Scott Mccammon, Jörg Peters Jan 1997

Computing Moments Of Piecewise Polynomial Surfaces, Carlos Gonzalez-Ochoa, Scott Mccammon, Jörg Peters

Department of Computer Science Technical Reports

No abstract provided.

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Performance Analysis And Visualization Tools For Parallel Computing, K. N. Pantazopoulos, Elias N. Houstis Jan 1997

Performance Analysis And Visualization Tools For Parallel Computing, K. N. Pantazopoulos, Elias N. Houstis

Department of Computer Science Technical Reports

No abstract provided.

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Lyapunov Exponents Of Linear Stochastic Functional-Differential Equations. Ii. Examples And Case Studies, Salah-Eldin A. Mohammed, Michael K. R. Scheutzow Jan 1997

Lyapunov Exponents Of Linear Stochastic Functional-Differential Equations. Ii. Examples And Case Studies, Salah-Eldin A. Mohammed, Michael K. R. Scheutzow

Articles and Preprints

We give several examples and examine case studies of linear stochastic functional differential equations. The examples fall into two broad classes: regular and singular, according to whether an underlying stochastic semi-flow exists or not. In the singular case, we obtain upper and lower bounds on the maximal exponential growth rate $\overlineλ1$(σ) of the trajectories expressed in terms of the noise variance σ . Roughly speaking we show that for small σ, $\overlineλ1$(σ) behaves like -σ2 /2, while for large σ, it grows like logσ. In the regular case, it is shown that a discrete Oseledec …

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An Invariant Of Basic Sets Of Smale Flows, Michael C. Sullivan Jan 1997

An Invariant Of Basic Sets Of Smale Flows, Michael C. Sullivan

Articles and Preprints

We consider one-dimensional flows which arise as hyperbolic invariant sets of a smooth flow on a manifold. Included in our data is the twisting in the local stable and unstable manifolds. A topological invariant sensitive to this twisting is obtained.

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Constraints On The Production Of Ultra–High-Energy Cosmic Rays By Isolated Neutron Stars, Aparna Venkatesan, M Coleman Miller, Angela V. Olinto Jan 1997

Constraints On The Production Of Ultra–High-Energy Cosmic Rays By Isolated Neutron Stars, Aparna Venkatesan, M Coleman Miller, Angela V. Olinto

Physics and Astronomy

The energetics, spectrum, and composition of cosmic rays with energies below ~1015 eV are fairly well explained by models involving supernova shocks. In contrast, no widely accepted theory exists for the origin of ultra-high-energy cosmic rays (UHECRs), which have energies above 1015 eV. Instead of proposing a specific model, here we place strong constraints on any model of UHECRs involving isolated neutron stars (no companions). We consider the total power requirements and show that the only viable power source associated with isolated neutron stars is rotation. Mechanisms based on accretion from the interstellar medium fall short of the …

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The Planet, 1997, Winter, Julie Irvin, Huxley College Of The Environment, Western Washington University Jan 1997

The Planet, 1997, Winter, Julie Irvin, Huxley College Of The Environment, Western Washington University

The Planet

No abstract provided.

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Future Horizons: Recent Literature In Sustainable Agriculture, Gabriel Hegyes, Charles A. Francis Jan 1997

Future Horizons: Recent Literature In Sustainable Agriculture, Gabriel Hegyes, Charles A. Francis

CARI Extension and Education Materials for Sustainable Agriculture

Here is one building block in the foundation for a future agriculture. Increasing trainer literacy in sustainable agriculture can be defined on several levels. At its most literal, it is an anthology of reviews familiarizing the reader with some of the authors, topics, and titles that have composed the sustainable agriculture literature over the last decade or more. It also serves as an annotated bibliography where the dry abstracts of many such works are replaced with insightful essays. Most importantly, this primer is a language text, exposing the user to the semantics, symbols, and syntax of sustainable agriculture. This collection …

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Semantic Analysis Of The Postscript Page Description Language, Ben Knuth Jan 1997

Semantic Analysis Of The Postscript Page Description Language, Ben Knuth

Honors Theses, 1963-2015

The Postscript page description language is a functional programming language. Central to the effective use of the language are the functional properties of delayed evaluation and referential transparency. Postscript performs all of its operations via distinct, multiple stacks which stores function binding lists, function parameters, and function code. By way of these stacks, Postscript creates dynamic computational states which leads identical expressions to evaluate to different results. This hints towards the polymorphic quality of an object-oriented language, even though it contradicts the functional precept of manifest interfaces thereby introducing a nonorthogonality. One other streak of object-orientation that shows up in …

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How Secure Transactions Are Achieved On The Internet Using Ssl: An Honors Presentation Of Internet Security Practices And Protocols, Julie Klinefelter Jan 1997

How Secure Transactions Are Achieved On The Internet Using Ssl: An Honors Presentation Of Internet Security Practices And Protocols, Julie Klinefelter

Honors Theses, 1963-2015

The goal of this project is to research and present the security protocol "Secure Sockets Layer" or as it is more commonly referred to, "SSL." SSL is one of the main encryption techniques used by the internet industry to help ensure the secure transfer of information across the internet. It is one of the main encryption techniques currently under review by Internet Engineering Task Force. SSL is comprised of a strict protocol that initiates a secure "session" between two computing devices. The session is established above the transport level (on the OSI model) and encrypts from the session up. Therefore …

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A Comparison Of The Kinetics Of Fatty-Acid Metabolism In Smokers And Nonsmokers, Patricia A. Valusek Jan 1997

A Comparison Of The Kinetics Of Fatty-Acid Metabolism In Smokers And Nonsmokers, Patricia A. Valusek

Honors Theses, 1963-2015

For many years, the United States government has required labels on all cigarette packages warning against the many ill effects associated with smoking. One of the major factors contributing to the unhealthy aspects of smoking is its profound impact on nutrient levels within the body. Free radicals found in both the gas and tar phases of cigarette smoke may pose a significant threat to the fatty-acid levels in the body. One method of assessing this threat is to examine the fatty-acid synthesis rates of smokers and nonsmokers. An assumption was made that a destruction of fatty-acids will be displayed as …

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Walking Thoughts, Hunter R. Rawlings Iii Jan 1997

Walking Thoughts, Hunter R. Rawlings Iii

Journal of the Iowa Academy of Science: JIAS

I've borrowed my title from a poem by Marvin Bell, a member of our Writers' Workshop, because I cannot think of state parks without thinking of my love for their hiking trails and the expansion of spirit they have brought me. State parks are more than nature preserves, more than recreational areas, though these functions are very important. They are also cultural and even spiritual resources, centers of emotional and psychic renewal.

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