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1997

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Articles 2041 - 2070 of 2498

Full-Text Articles in Physical Sciences and Mathematics

Arithmetic Of A Semigroup Of Series In Legendre Functions Of The Second Kind, I. P. Il'inskaja Jan 1997

Arithmetic Of A Semigroup Of Series In Legendre Functions Of The Second Kind, I. P. Il'inskaja

Turkish Journal of Mathematics

In the framework of D. Kendall's theory of Delphic semigroups, a semigroup of series in Legendre functions of the second kind is studied. The basic factorization theorems are prowed, the classes of infinitely divisible elements and of elements without indecomposable factors are completely described, the density of the class of indecomposable elements is established.

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The Reliability Of Jung-Biggs-Moorhead Method For Cholesterol Determination In The Presence Of Ergosterol, Lemi Türker, Şahinde Demi̇rci̇, Marjan Akdağ Jan 1997

The Reliability Of Jung-Biggs-Moorhead Method For Cholesterol Determination In The Presence Of Ergosterol, Lemi Türker, Şahinde Demi̇rci̇, Marjan Akdağ

Turkish Journal of Chemistry

In the present study, the reliability of Jung-Biggs-Moorhead method for cholesterol determination has been tested in the presence of another steroid, ergosterol. It was observed that presence of ergosterol interferes with the absorbance measurement of cholesterol. When both steroids are present in the sample maximum absorption wavelength are not shifted by the mutual interaction but absorbance values are changed considerably. Therefore this method may be used only for qualitative bu not quantitative analysis for cholesterol in the presence of ergosterol.

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A Study Of The Thermodynamical Interactions Of Bisphenol-A Polycarbonate With Some Solvents By Gas Chromatography, Özlem Cankurtaran, Ferdane Yilmaz Jan 1997

A Study Of The Thermodynamical Interactions Of Bisphenol-A Polycarbonate With Some Solvents By Gas Chromatography, Özlem Cankurtaran, Ferdane Yilmaz

Turkish Journal of Chemistry

Retentin diagrams of polycarbonate for n-nonane, ethyl acetate and n-butyl acetate were obtained using inverse gas chromatography in the temperature range 80-240^{\circ}C. The specific retention volumes, V^{\circ}_{g} the Flory-Huggins interaction parmeters, \chi^{\infty}_{12}, interaction parameters, \chi^{\ast}_{12}, and effective exchange-energy parameters \bar{X}_{12} of the equation-of-state theory of polycarbonate for n-octane, n-nonane, n-decane, ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate and isoamyl acetate were obtained in the temperature range 200-240^{\circ}C. The parameter \delta_2 was estimated to be 10.7 (cal/cm^3)^{1/2} at room temperature using the \chi^{\infty}_{12} extrapolated to room temperature. Keywords: Bisphenol-A polycarbonate, polymer-solvent interactions, inverse gas chromatography, solubility parameter.

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On The Theory Of A Certain Class Of Quadratic Pencils Of Matrices And Its Applications, G.Sh. Guseinov, G. Oturanç Jan 1997

On The Theory Of A Certain Class Of Quadratic Pencils Of Matrices And Its Applications, G.Sh. Guseinov, G. Oturanç

Turkish Journal of Mathematics

This paper is devoted to the study of the properties of eigenvalues and eigenvectors of quadratic pencil \lambda^2C - \lambdaR - J , where C is a positive diagonal matrix, R is an arbitrary real diagonal matrix, J is a ,, tridiagonal" real symmetric and positive matrix. The obtained results are then used to solve the corresponding system of differential equations with boundary and initial conditions. Kev Words: Quadratic pencijs, eigenvalues, eigenvectors.

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Near Ultrafilters And Luc-Compactification Of Real Numbers, Mahmut Koçak Jan 1997

Near Ultrafilters And Luc-Compactification Of Real Numbers, Mahmut Koçak

Turkish Journal of Mathematics

In this work we will investigate some of the topological properties of the Luc compactification of real numbers R in terms of the concept of near ultrafilters.

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Some New Sequence Spaces Defined By A Sequence Of Moduli, Ayhan Esi̇ Jan 1997

Some New Sequence Spaces Defined By A Sequence Of Moduli, Ayhan Esi̇

Turkish Journal of Mathematics

In this paper we introduce and exaamine some properties of three sequence spaces defined by using a sequence of moduli.

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Locally Finite Barely Transitive Permutation Group With Almost Nilpotent Point Stabilizers, Mahmut Kuzucuoğlu Jan 1997

Locally Finite Barely Transitive Permutation Group With Almost Nilpotent Point Stabilizers, Mahmut Kuzucuoğlu

Turkish Journal of Mathematics

We show that the groups mentioned in the title are solvable. Moreover, a point stabilizer H of the locally finite barely transitive group G is almost nilpotent, whenever the indices H : H \cap H^g (g \in G) have a finite upper bound.

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Semiclassical Approach To The Hydrogen-Exchange Reaction- Reactive And Transition-State Dynamics, Sophya V. Garashchuk, Grossmann Frank, David Tannor Jan 1997

Semiclassical Approach To The Hydrogen-Exchange Reaction- Reactive And Transition-State Dynamics, Sophya V. Garashchuk, Grossmann Frank, David Tannor

Faculty Publications

Scattering matrix elements and symmetric transition-state resonances for the collinear H 2 + H → H + H 2 reaction are obtained using a time-dependent approach. The correlation function between reactant channel wavepackets and product channel wavepackets is used to determine the S-matrix elements. In a similar fashion, autocorrelation functions are used to extract the positions and widths of transition-state resonances. The time propagation of the wavepackets is performed by the improved semiclassical frozen Gaussian method of Herman and Kluk, which is an initial value, uniformly converged method. The agreement between the quantum and semiclassical results is far better …

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Topological Constraints On Hmo Hetereoatom Parameters, Lemi Türker Jan 1997

Topological Constraints On Hmo Hetereoatom Parameters, Lemi Türker

Turkish Journal of Chemistry

Within the Hückel molecular orbital framework, the effect of topological factors on the selection of heteroatom parameters for heteroconjugated systems is discussed.

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Examination Of Historical Textiles With Dyestuff Analyses By Tlc And Derivative Spectrophotometry, Recep Karadağ, Emre Dölen Jan 1997

Examination Of Historical Textiles With Dyestuff Analyses By Tlc And Derivative Spectrophotometry, Recep Karadağ, Emre Dölen

Turkish Journal of Chemistry

A group of historical textiles in the Topkapi Museum, i.e., silk brocades classified as 16th century pieces by art historians, were investigated by TLC and spectrophometric analyses of their dyestuffs for the purpose of dating these pieces. The dyestuffs contained intextile fibers were extracted with acid solutions of varying strength, and the acid extracts were analyzed by both TLC and spectrophotometry, either directly or after an organic solvent extraction step. The first derivative spectra proved to provide more information than the main spectra. In order to eliminate possible interferences in spectrophotometry arising from impurities in the fibers, e.g., compounds containing …

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Catalytically Active Intermediates In Photochemical Metathesis, Çetin Bozkurt, Yavuz İmamoğlu Jan 1997

Catalytically Active Intermediates In Photochemical Metathesis, Çetin Bozkurt, Yavuz İmamoğlu

Turkish Journal of Chemistry

The nature of the active species in photocatalytic metathesis reaction was investigated. The formation of Wittig-type addition products with benzaldehyde indicates that catalytically active carbene is the product of olefin and tungsten hexacarbonyl under reaction conditions.

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Some Remarks On Solid State Polymerization, George Adler Jan 1997

Some Remarks On Solid State Polymerization, George Adler

Turkish Journal of Chemistry

No abstract provided.

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Conducting Polymer Grafts Of Polypyrrole, Levent Toppare Jan 1997

Conducting Polymer Grafts Of Polypyrrole, Levent Toppare

Turkish Journal of Chemistry

Conducting polymer grafts of pyrrole with poly[(methyl methacrylate)-co-(2-(N-pyrollyl) ethyl methacrylate)] wwere synthesized via elctrochemical polymerization of pyrrole in different media. Samples were characterized by SEM, thermal analysis and conductivity measurements.

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Properties And Macromolecular Structure Of Unacetylated And Acetylated Nata De Coco, Ma. Assunta C. Cuyegkeng, Ma. Amy L. Dimalanta Jan 1997

Properties And Macromolecular Structure Of Unacetylated And Acetylated Nata De Coco, Ma. Assunta C. Cuyegkeng, Ma. Amy L. Dimalanta

Chemistry Faculty Publications

This study aims to gain more insight into the supramolecular structure of the cellulose in nata de coco, and to compare its ability to be modified with the known types of cellulose. The investigations were done using IR spectroscopy and thennal analysis. The IR spectra of microcrystalline cellulose were identical to cellulose spectra. However, those of dried nata de coco cellulose showed additional peaks that indicated a loss of inter- and intra-sheet hydrogen bonding, usually extensive in other cellulose forms where sheets are the prevalent secondary structures. This kind of structure would be consistent with the necessary framework for gel …

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Resolution Of Local Inconsistency In Identification, Douglas Ray Anderson, Martin Zwick Jan 1997

Resolution Of Local Inconsistency In Identification, Douglas Ray Anderson, Martin Zwick

Systems Science Faculty Publications and Presentations

This paper reports an algorithm for the resolution of local inconsistency in information-theoretic identification. This problem was first pointed out by Klir as an important research area in reconstructability analysis. Local inconsistency commonly arises when an attempt is made to integrate multiple data sources, i.e., contingency tables, which have differing common margins. For example, if one ha)s an AB table and a BC table, the B margins obtained from the two tables may disagree. If the disagreement can be assigned to sampling error, then one can arrive at a compromise B margin, adjust the original AB and BC tables to …

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Geographic Variation And Genetic Relationships In Populations Of The Androniscus Dentiger Complex From Central Italy (Isopoda, Oniscidea, Trichoniscidae), Gabriele Gentile, Giuliana Allegrucci Jan 1997

Geographic Variation And Genetic Relationships In Populations Of The Androniscus Dentiger Complex From Central Italy (Isopoda, Oniscidea, Trichoniscidae), Gabriele Gentile, Giuliana Allegrucci

International Journal of Speleology

Androniscus dentiger is a terrestrial isopod distributed from Great Britain to North Africa, inhabiting humid edafic environments, superficial underground compartments and both natural and artificial caves. In this study allozyme data have been used to investigate the geographic variation and the genetic relationships of several populations of A. dentiger from Central Italy, using as outgroups populations from four congeneric species, A. calcivagus, A. cfr. subterraneus, A. spelaeorum, and A. degener. Multivariate analysis of A. dentiger allele frequencies indicates the existence of a group of populations (group A) distributed in a wide geographic area which are genetically …

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Does Good Project Management Ensure Successful Software Development?, Julie Lisa Eldridge Jan 1997

Does Good Project Management Ensure Successful Software Development?, Julie Lisa Eldridge

Theses : Honours

For many years the development of computer software has been plagued by poor customer satisfaction caused by missed schedules, underestimated budgets and the development of products which do not meet requirements. The ever increasing reliance on computers, as reported by Sommerville ''the result of the proliferation of computer systems into all aspects of life and business is that personal, corporate, national and international economies are [becoming] increasingly dependant on computers and software systems" ( 1992, p.2), calls for more stable software which can be developed within time and budget constraints. To achieve this, software development activities must be analysed and …

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Dialogue And Deliberation, Ronald P. Loui, Diana M. Moore Jan 1997

Dialogue And Deliberation, Ronald P. Loui, Diana M. Moore

All Computer Science and Engineering Research

Formal accounts of negotiation tend to invoke the strategic models of conflict which have been impressively developed by game theorists in this half-century. For two decades, however, research on artificial intelligence (AI) has produced a different formal picture of the agent and of the rational deliberations of agents. AI's models are not based simply on intensities of preference and quantities of probability. AI's models consider that agents use language in various ways, that agents use and convey knowledge, that agents plan, search, focus, and argue. Agents can choose their language, apply their knowledge, change their plans, continue their search, shift …

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Noise-Tolerant Parallel Learning Of Geometric Concepts, Nader H. Bshouty, Sally A. Goldman, H. David Mathias Jan 1997

Noise-Tolerant Parallel Learning Of Geometric Concepts, Nader H. Bshouty, Sally A. Goldman, H. David Mathias

All Computer Science and Engineering Research

We present several efficient parallel algorithms for PAC-learning geometric concepts in a constant-dimensional space. The algorithms are robust even against malicious classification noise of any rate less than 1/2. We first give an efficient noise-tolerant parallel algorithm to PAC-learn the class of geometric concepts defined by a polynomial number of (d-1)-dimensional hyperplanes against an arbitrary distribution where each hyperplane has a slope from a set of known slopes. We then describe how boosting techniques can be used so that our algorithms' dependence on {GREEK LETTER} and {DELTA} does not depend on d. Next we give an efficient noise-tolerant parallel algorithm …

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A Theoretical And Empirical Study Of A Noise-Tolerant Algorithm To Learn Geometric Patterns, Sally A. Goldman, Stephen D. Scott Jan 1997

A Theoretical And Empirical Study Of A Noise-Tolerant Algorithm To Learn Geometric Patterns, Sally A. Goldman, Stephen D. Scott

All Computer Science and Engineering Research

Developing the ability to recognize a landmark from a visual image of a robot's current location is a fundamental problem in robotics. We describe a way in which the landmark matching problem can be mapped to that of learning a one-dimensional geometric pattern. The first contribution of our work is an efficient noise-tolerant algorithm (designed using the statistical query model) to PAC-learn the class of one-dimensional geometric patterns. The second contribution of our work is an empirical study of our algorithm that provides at least some evidence that statistical query algorithms may be valuable for use in practice for handling …

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Noise-Tolerant Distribution-Free Learning Of General Geometric Concepts, Nader H. Bshouty, Sally A. Goldman, H. David Mathias, Subhash Suri, Hisao Tamaki Jan 1997

Noise-Tolerant Distribution-Free Learning Of General Geometric Concepts, Nader H. Bshouty, Sally A. Goldman, H. David Mathias, Subhash Suri, Hisao Tamaki

All Computer Science and Engineering Research

We present an efficient algorithm for PAC-learning a very general class of geometric concepts over Rd for fixed d. More specifically, let T be any set of s halfspaces. Let x = (x1,...,xd) be an arbitrary point in Rd. With each t Є T we associate a boolean indicator function It(x) which is 1 if and only if x is in the halfspace t. The concept class Cds that we study consists of all concepts formed by any boolean function over It1, ...Its for ti Є T. This class is much more general than any geometric concept class known to …

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An Error Control Scheme For Large-Scale Multicast Applications, Christos Papadopoulos, Guru Parulkar, George Varghese Jan 1997

An Error Control Scheme For Large-Scale Multicast Applications, Christos Papadopoulos, Guru Parulkar, George Varghese

All Computer Science and Engineering Research

Retransmission based error control for large scale multicast applications is difficult because of two main problems: request implosion and lack of local recovery. Existing schemes (SRM, RMTP, TMTP, LBRRM) have good solutions to request implosion, but only approximate solutions (e.g., based on scoped multicast) for the local recovery problem. Our scheme achieves finer grain fault recovery by exploiting new forwarding services that allow us to create a dynamic hierarchy of receivers. We use a new paradigm, where routers provide a more refined form of multicasting (that may be useful to other applications), that enables local recovery. The new services, however, …

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Reducing Web Latencies Using Precomputed Hints, Girish P. Chandranmenon, George Varghese Jan 1997

Reducing Web Latencies Using Precomputed Hints, Girish P. Chandranmenon, George Varghese

All Computer Science and Engineering Research

Current network technology is bandwidth-rich but latency-poor; thus round-trip delays will dominate access latency for web traffic. We describe four new techniques that reduce the round-trips needed for web accesses. The techniques are based on the paradigm of preprocessing a web page to collect information about links and inline data in the page. Stored Address Binding almost always eliminates the DNS lookup (which can cost seconds) at the start of a transaction. In Informed Server Proxying, a server tells its client that it has cached pages referenced in a page the client just retrieved; this allows the client to retrieve …

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An Architecture For Monitoring Visualization And Control Of Gigabit Networks, Guru Parulkar, Douglas Schmidt, Eileen Kraemer, Jonathan Turner, Anshul Kantawala Jan 1997

An Architecture For Monitoring Visualization And Control Of Gigabit Networks, Guru Parulkar, Douglas Schmidt, Eileen Kraemer, Jonathan Turner, Anshul Kantawala

All Computer Science and Engineering Research

We propose a network monitoring, visualization and control system (NMVC) that ensures adequate quality of service to network users while maintaining high network resource utilization. The main components of our system are a network probe, an endsystem probe, software network management agents that provide extensible multi-attribute event filtering for highly scalable data/event collection, network operation centers (NOCs) which can remotely install and (re)configure these agents, efficient online event ordering algorithms that can help synthesize and display a consistent view of network health, status and performance and a View Choreographer that allows management applications and administrators to specify the mapping of …

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Euphoria Reference Manual, T. Paul Mccartney, Kenneth J. Goldman Jan 1997

Euphoria Reference Manual, T. Paul Mccartney, Kenneth J. Goldman

All Computer Science and Engineering Research

EUPHORIA is a user interface management system that enables end-users to create direct manipulation graphical user interfaces (GUIs) through interactive drawing. Used in conjunction with The Programmers' Playground, a distributed programming environment, end-users can dynamically create and associate GUI components with an underlying application without programming, This document describes EUPHORIA's functionality.

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Costs Of Constraint Based Networks On A Sphere, Hongzhou Ma, Jonathan Turner Jan 1997

Costs Of Constraint Based Networks On A Sphere, Hongzhou Ma, Jonathan Turner

All Computer Science and Engineering Research

This paper estimates the link costs of constraint based nonblocking ATM networks on a sphere. Analytical results are obtained when switches are uniformly distributed on the surface of a unit sphere and every switch has source and sink capacity of one, and the results are compared with simulations.

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An Algorithm For Message Delivery In A Micromobility Environment, Amy L. Murphy, Gruia-Catalin Roman, George Varghese Jan 1997

An Algorithm For Message Delivery In A Micromobility Environment, Amy L. Murphy, Gruia-Catalin Roman, George Varghese

All Computer Science and Engineering Research

With recent advances in wireless communication and the ubiquity of laptops, mobile computing has become an important research area. An essential problem in mobile computing is the delivery of a message from a source to either a single mobile node, unicast, or to a group of mobile nodes, multicast. Standard solutions proposed for macromobility (Mobile IP) and micromobility (cellular phones) for the unicast problem rely on tracking the mobile node. Tracking solutions scale badly when mobile nodes move frequently, and do not generalize well to multicast delivery. Our paper proposes a new message delivery algorithm for micromobility based on a …

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Symmetrical Routes And Reverse Path Congestion Control, Rajib Ghosh, George Varghese Jan 1997

Symmetrical Routes And Reverse Path Congestion Control, Rajib Ghosh, George Varghese

All Computer Science and Engineering Research

We describe new mechanisms to deal with asymmetries that arise in routing protocols. We show how to avoid route asymmetries (due to non-unique shortest paths) by adding random integer link costs. We show in detail how RIP can be modified to avoid route asymmetry with high probability, without affecting either its efficiency or performance metrics such as convergence time. Symmetrical intra-domain routing also makes possible a new form of congestion control that we call Reverse Path Congestion Control (RPCC). We show, using simulations, that RPCC can augment existing TCP congestion control mechanisms to improve start up behavior and to avoid …

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Enhancements To 4.4 Bsd Unix For Efficient Networked Multimedia In Project Mars, Milind M. Buddhikot, Xin Jane Chen, Dakang Wu, Guru M. Parulkar Jan 1997

Enhancements To 4.4 Bsd Unix For Efficient Networked Multimedia In Project Mars, Milind M. Buddhikot, Xin Jane Chen, Dakang Wu, Guru M. Parulkar

All Computer Science and Engineering Research

Cluster based architectures that employ high performance inexpensive Personal Computers (PCs) interconnected by high speed commodity interconnect have been recognized as a cost-effective way of building high performance scalable Multimedia-On-Demand (MOD) storage servers [4, 5, 7, 9]. Typically, the PCs in these architectures run operating systems such as UNIX that have traditionally been optimized for interactive computing. They do not provide fast disk-to-network data paths and guaranteed CPU and storage access. This paper reports enhancements to the 4.4 BSD UNIX system carried out to rectify these limitations in the context of our Project Massively-parallel And Real-time Storage (MARS) [7]. We …

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An Introduction To Mobile Unity, Gruia-Catalin Roman, Peter J. Mccann Jan 1997

An Introduction To Mobile Unity, Gruia-Catalin Roman, Peter J. Mccann

All Computer Science and Engineering Research

Traditionally, a distributed system has been viewed as a collection of fixed computational elements connected by a static network. Prompted by recent advances in wireless communications rechnology, the emerging field of mobile computing is challenging these assumptions by providing mobile hosts with connectivity that may change over time, raising the possibility that hosts may be called upon to operate while only weakly connected to or while completely disconnected from other hosts. We define a concurrent mobile system as one where independently executing coponents may migrate through some space during the course of the computation, and where the pattern of connectivity …

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