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Articles 24901 - 24930 of 27391

Full-Text Articles in Physical Sciences and Mathematics

Analysis And Finite Element Approximation Of Optimal Control Problems For The Stationary Navier-Stokes Equations With Dirichlet Controls, M. D. Gunzburger, L. S. Hou, Tom Svobodny Jan 1991

Analysis And Finite Element Approximation Of Optimal Control Problems For The Stationary Navier-Stokes Equations With Dirichlet Controls, M. D. Gunzburger, L. S. Hou, Tom Svobodny

Mathematics and Statistics Faculty Publications

Optimal control problems for the stationary Navier-Stokes equations are examined from analytical and numerical points of view. The controls considered are of Dirichlet type, that is, control is effected through the velocity field on (or the mass flux through) the boundary; the functionals minimized are either the viscous dissipation or the L4-distance of candidate flows to some desired flow. We show that optimal solutions exist and justify the use of Lagrange multiplier techniques to derive a system of partial differential equations from which optimal solutions may be deduced. We study the regularity of solutions of this system. The n, finite …

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Minimax-Optimal Stop Rules And Distributions In Secretary Problems, Theodore P. Hill, Ulrich Krengel Jan 1991

Minimax-Optimal Stop Rules And Distributions In Secretary Problems, Theodore P. Hill, Ulrich Krengel

Research Scholars in Residence

For the secretary (or best-choice) problem with an unknown number N of objects, minimax-optimal stop rules and (worst-case) distributions are derived, under the assumption that $N$ is a random variable with unknown distribution, but known upper bound n. Asymptotically, the probability of selecting the best object in this situation is of order of (log n)-1. For example, even if the only information available is that there are somewhere between 1 and 100 objects, there is still a strategy which will select the best item about one time in five.

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The Probabilities Associated With The Game Jai-Alai, Robert Hesse Jan 1991

The Probabilities Associated With The Game Jai-Alai, Robert Hesse

Honors Theses, 1963-2015

This paper studies the probabilities within the game Jai-alai. Before explaining the probabilities, one first needs to understand the game itself. Jai-alai is a racquetball-like game where eight ordered players compete against one another in the following manner: Player 1 plays Player 2. The winner of this game plays Player 3, while the loser goes to the end of the line behind Player 8. In the first seven games, 1 versus 2," versus 3,"""? versus 8, the winner is awarded one point, and in every game after that two points. A player wins the match when he is the first …

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Nonlinear-Interaction Of A Detonation Vorticity Wave, D. G. Lasseigne, T. L. Jackson, M. Y. Hussaini Jan 1991

Nonlinear-Interaction Of A Detonation Vorticity Wave, D. G. Lasseigne, T. L. Jackson, M. Y. Hussaini

Mathematics & Statistics Faculty Publications

The interaction of an oblique, overdriven detonation wave with a vorticity disturbance is investigated by a direct two-dimensional numerical simulation using a multidomain, finite-difference solution of the compressible Euler equations. The results are compared to those of linear theory, which predict that the effect of exothermicity on the interaction is relatively small except possibly near a critical angle where linear theory no longer holds. It is found that the steady-state computational results whenever obtained in this study agree with the results of linear theory. However, for cases with incident angle near the critical angle, moderate disturbance amplitudes, and/or sudden transient …

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The Expected Capacity Of Concentrators, Nicholas Pippenger Jan 1991

The Expected Capacity Of Concentrators, Nicholas Pippenger

All HMC Faculty Publications and Research

The expected capacity of a class of sparse concentrators called modular concentrators is determined. In these concentrators, each input is connected to exactly two outputs, each output is connected to exactly three inputs, and the girth (the length of the shortest cycle in the connexion graph) is large. Two definitions of expected capacity are considered. For the first (which is due to Masson and Morris), it is assumed that a batch of customers arrive at a random set of inputs and that a maximum matching of these customers to servers at the outputs is found. The number of unsatisfied requests …

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On A Lower Bound For The Redundancy Of Reliable Networks With Noisy Gates, Nicholas Pippenger Jan 1991

On A Lower Bound For The Redundancy Of Reliable Networks With Noisy Gates, Nicholas Pippenger

All HMC Faculty Publications and Research

A proof is provided that a logarithmic redundancy factor is necessary for the reliable computation of the parity function by means of a network with noisy gates. This result was first stated by R.L. Dobrushin and S.I. Ortyukov (1977). However, the authors believe that the analysis given by Dobrushin and Ortyukov is not entirely correct. The authors establish the result by following the same steps and by replacing the questionable part of their analysis with entirely new arguments.

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Stochastic Orderings Induced By Star-Shaped Functions, Henry A. Krieger Jan 1991

Stochastic Orderings Induced By Star-Shaped Functions, Henry A. Krieger

All HMC Faculty Publications and Research

The non-decreasing functions whicl are star-shaped and supported above at each point of a non-empty closed proper subset of the real line induce an ordering, on the class of distribution functions with finite first moments, that is strictly weaker than first degree stochastic dominance and strictly stronger than second degree stochastic dominance. Several characterizations of this ordering are developed, both joint distribution criteria and those involving only marginals. The latter are deduced from a decomposition theorem, which reduces the problem to consideration of certain functions which are star-shaped on the complement of an open interval.

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Selection Networks, Nicholas Pippenger Jan 1991

Selection Networks, Nicholas Pippenger

All HMC Faculty Publications and Research

An upper bound asymptotic to $2n\log _e n$ is established for the number of comparators required in a network that classifies $n$ values into two classes, each containing $n / 2$ values, with each value in one class less than or equal to each value in the other. (The best lower bound known for this problem is asymptotic to $(n / 2)\log _2 n$.)

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When Is Every Order Ideal A Ring Ideal?, Melvin Henriksen, Suzanne Larson, Frank A. Smith Jan 1991

When Is Every Order Ideal A Ring Ideal?, Melvin Henriksen, Suzanne Larson, Frank A. Smith

All HMC Faculty Publications and Research

A lattice-ordered ring ℝ is called an OIRI-ring if each of its order ideals is a ring ideal. Generalizing earlier work of Basly and Triki, OIRI-rings are characterized as those f-rings ℝ such that ℝ/I is contained in an f-ring with an identity element that is a strong order unit for some nil l-ideal I of ℝ. In particular, if P(ℝ) denotes the set of nilpotent elements of the f-ring ℝ, then ℝ is an OIRI-ring if and only if ℝ/P(ℝ) is contained in an f-ring with an identity element that is a strong order unit.

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Modulated, Frequency-Locked, And Chaotic Cross-Waves, William B. Underhill, Seth Lichter, Andrew J. Bernoff Jan 1991

Modulated, Frequency-Locked, And Chaotic Cross-Waves, William B. Underhill, Seth Lichter, Andrew J. Bernoff

All HMC Faculty Publications and Research

Measurements were made of the wave height of periodic, quasi-periodic, and chaotic parametrically forced cross-waves in a long rectangular channel. In general, three frequencies (and their harmonics) may be observed: the subharmonic frequency and two slow temporal modulations — a one-mode instability associated with streamwise variation and a sloshing motion associated with spanwise variation. Their interaction, as forcing frequency, f, and forcing amplitude, a, were varied, produced a pattern of Arnold tongues in which two or three frequencies were locked. The overall picture of frequency-locked and -unlocked regions is explained in terms of the Arnold tongues predicted by …

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An Analysis Of The Monitored Electronic Alarm Activations In The Perth Metropolitan Area, Lynnette M. Bloom, James M. Cross, David Mcdougall Jan 1991

An Analysis Of The Monitored Electronic Alarm Activations In The Perth Metropolitan Area, Lynnette M. Bloom, James M. Cross, David Mcdougall

Research outputs pre 2011

This study as indicated in [7] was carried out under the auspices of Edith Cowan University's Institute of Security and Applied Technology and had the support of the Western Australian Police and the Perth-based Central Monitoring Agencies. The data analysed was obtained essentially from Police records, backed up by data from two of Perth's larger security companies, and consists of all the monitored alarms in the Perth Metropolitan Area which were attended by the police in the months of May and September 1989.In our consideration of the frequency of alarms by time of day and day of week, and the …

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Intelligent Structural Operators For The K-Way Graph Partitioning Problem, Gregor Von Laszewski Jan 1991

Intelligent Structural Operators For The K-Way Graph Partitioning Problem, Gregor Von Laszewski

Northeast Parallel Architecture Center

A parallel genetic algorithm for the graph partitioning problem is presented, which combines general heuristic algorithms with techniques that are described in evolution theory. In the parallel genetic algorithm the selection of a mate is restricted to a local neighborhood. In addition, the parallel genetic algorithm executes an adaptation step after an individual is generated, with the genetic operators crossover and mutation. During the adaptation step the solution is improved by a common algorithm. Another selection step decides if the adapted descendant should replace the parent individual. Instead of using a uniform crossover operator a more intelligent crossover operator, which …

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Some Remarks On Reproducing Kernel Krein Spaces, Daniel Alpay Jan 1991

Some Remarks On Reproducing Kernel Krein Spaces, Daniel Alpay

Mathematics, Physics, and Computer Science Faculty Articles and Research

The one-to-one correspondence between positive functions and reproducing kernel Hilbert spaces was extended by L. Schwartz to a (onto, but not one-to-one) correspondence between difference of positive functions and reproducing kernel Krein spaces. After discussing this result, we prove that matrix value function K(z,ω) symmetric and jointly analytic in z and ω in a neighborhood of the origin is the reproducing kernel of a reproducing kernel Krein space. We conclude with an example showing that such a function can be the reproducing kernel of two different Krein spaces.

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The Impact Of Tourism On Block Island, Thomas Green Jan 1991

The Impact Of Tourism On Block Island, Thomas Green

Marine Affairs Theses and Major Papers

This thesis examines the impacts of tourism on the residents of Block Island. More specifically the study seeks to identify the specific areas of concern, as perceived by the residents, in three major areas of impact: economic, social and environmental. It was hypothesized that the residents of Block Island, a mature tourist destination area, had formulated perceptions of the impacts of tourism and that these perceptions, if analyzed, would identify protection of the environment and threats to the Island's lifestyle as major concerns. Factor analysis was employed to analyze survey responses from residents on questions regarding tourism on Block Island. …

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Testing Exponentiality Against Idmrl Distributions With Unknown Change Point, D. L. Hawkins, Clive Loader, Subhash Kochar Jan 1991

Testing Exponentiality Against Idmrl Distributions With Unknown Change Point, D. L. Hawkins, Clive Loader, Subhash Kochar

Mathematics Technical Papers

Guess, Hollander and Proschan (1986) proposed tests for exponentiality versus IDMRL (increasing initially and then decreasing mean residual life) distributions when the change point, or corresponding quantile, is known. In this paper we propose two tests which do not require such knowledge of the change point. The tests are based on estimates of functionals of the cdf which discriminate between the exponential and IDMRL families.

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On Electron Attraction In The Diatomic Bond, Donald Greenspan Jan 1991

On Electron Attraction In The Diatomic Bond, Donald Greenspan

Mathematics Technical Papers

Previously, it was shown that classical simulation of the ground state diatomic hydrogen, deuterium and tritium molecules yielded the correct vibrational frequencies and average molecular diameters under the assumption that the bonding electrons attracted, rather than repelled. It is shown here that the assumption of electron attraction also yields the correct vibrational frequencies and average molecular diameters for [see pdf for notation].

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A Study Of The Survival Rate Of The Hepatitis B Virus, James Abraham Houck Iii Jan 1991

A Study Of The Survival Rate Of The Hepatitis B Virus, James Abraham Houck Iii

UNF Graduate Theses and Dissertations

Hepatitis B virus (HBV) is one of many viruses transmitted through the blood or body fluids. This paper concentrates on a mathematical study of the survival rate of HBV. Using data which includes the survival time for individuals who were diagnosed as being affected by HBV and those who died from HBV, we fit non-linear models to study the survival time for people affected by the virus. Survival probabilities suggest an exponential curve for the survival time. We also consider a pure death process which is a stochastic model for the survival time of the individuals affected. Our results show …

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Competition Between Generic And Nongeneric Fronts Inenvelope Equations, James A. Powell, A. C. Newell, C. K. R. T. Jones Jan 1991

Competition Between Generic And Nongeneric Fronts Inenvelope Equations, James A. Powell, A. C. Newell, C. K. R. T. Jones

James A. Powell

Arguments are presented for understanding the selection of the speed and the nature of the fronts that join stable and unstable states on the supercritical side of first-order phase transitions. It is suggested that from compact support, nonpositive-definite initial conditions, observable front behavior occurs only when the asymptotic spatial structure of a trajectory in the Galilean ordinary differential equation (ODE) corresponds to the most unstable temporal mode in the governing partial differential equation (PDE). This selection criterion distinguishes between a "nonlinear" front, which has its origin in the first-order nature of the bifurcation, and a "linear" front. The nonlinear front …

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A Double Chain Of Coupled Circuits In Analogy With Mechanical Lattices, J. N. Boyd, P. N. Raychowdhury Jan 1991

A Double Chain Of Coupled Circuits In Analogy With Mechanical Lattices, J. N. Boyd, P. N. Raychowdhury

Mathematics and Applied Mathematics Publications

A unitary transformation obtained from group theoretical considerations is applied to the problem of finding the resonant frequencies of a system of coupled LC-circuits. This transformation was previously derived to separate the equations of motion for one dimensional mechanical lattices. Computations are performed in matrix notation. The electrical system is an analog of a pair of coupled linear lattices. After the resonant frequencies have been found, comparisons between the electrical and mechanical systems are noted.

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Refined Approximations Of The Solutions Of A Coupled System With Turning Points, W. A. Harris, S. Shao Jan 1991

Refined Approximations Of The Solutions Of A Coupled System With Turning Points, W. A. Harris, S. Shao

Mathematics and Statistics Faculty Publications

We present in this paper the asymptotic behavior of solutions of a boundary value problem for a coupled system of differential equations u″ = ν, εν″ + f(u, u′)ν′ - g(x, u, u′)ν = 0 on a compact interval I, where f(u, u′) has turning points in I. We provide upper and lower solutions, β(x, ε) and α(x, ε), respectively, which bound solutions, exhibiting boundary layer and interior layer behavior, for which limε → 0+ {β(x, ε) - α(x, ε)} = 0 uniformly on I.

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Estimation In A Marked Poisson Error Recapture Model Of Software Reliability, Rajan Gupta Jan 1991

Estimation In A Marked Poisson Error Recapture Model Of Software Reliability, Rajan Gupta

Mathematics & Statistics Theses & Dissertations

Nayak's (1988) model for the detection, removal, and recapture of the errors in a computer program is extended to a larger family of models in which the probabilities that the successive programs produce errors are described by the tail probabilities of discrete distribution on the positive integers. Confidence limits are derived for the probability that the final program produces errors. A comparison of the asymptotic variances of parameter estimates given by the error recapture and by the repetitive-run procedure of Nagel, Scholz, and Skrivan (1982) is made to determine which of these procedures efficiently uses the test time.

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Analytic Continuation In Bergman Spaces And The Compression Of Certain Toeplitz Operators, William T. Ross Jan 1991

Analytic Continuation In Bergman Spaces And The Compression Of Certain Toeplitz Operators, William T. Ross

Department of Math & Statistics Faculty Publications

Let G be a Jordan domain and K C G be relatively closed with Area(K) = 0. Let A2 (G\K) and A2(G) be the Bergman spaces on G\K, respectively G and define N = A2(G\K) Ɵ A2 (G). In this paper we show that with a mild restriction on K, every function in N has an analytic continuation across the analytic arcs of aG that do not intersect K. This result will be used to discuss the Fredholm theory of the operator Cf = PNTf│N, where f ϵ C(G) …

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A Note On Nonabelian (64, 28, 12) Difference Sets, James A. Davis Jan 1991

A Note On Nonabelian (64, 28, 12) Difference Sets, James A. Davis

Department of Math & Statistics Faculty Publications

The existence of difference sets in abelian 2-groups is a recently settled problem [5]; this note extends the abelian constructs of difference sets to nonabelian groups of order 64.

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Shadow Casting Phenomena At Newgrange, Frank Prendergast Jan 1991

Shadow Casting Phenomena At Newgrange, Frank Prendergast

Articles

A digital model of the Newgrange passage tomb and surrounding ring of monoliths known as the Great Circle is used to investigate sunrise shadow casting phenomena at the monument. Diurnal variation in shadow directions and lengths are analysed for their potential use in the Bronze Age to indicate the passage of seasonal time. Computer-aided simulations are developed from a photogrammetric survey to accurately show how three of the largest monoliths, located closest to the tomb entrance and archaeologically coded GC1, GC-1 and GC-2, cast their shadows onto the vertical face of the entrance kerbstone, coded K1. The phenomena occur at …

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Ein Beitrag Zur Klassifikation Von Koppelkurven (A Contribution To The Classification Of Coupler Curves), Jorg Feldvoss, Wolfram Funk, Peter Tolle Jan 1991

Ein Beitrag Zur Klassifikation Von Koppelkurven (A Contribution To The Classification Of Coupler Curves), Jorg Feldvoss, Wolfram Funk, Peter Tolle

University Faculty and Staff Publications

A study of the coupler curves of four-bar and Watt mechanisms is undertaken either theoretically or based on a computer program that is integrated in a CAD-System. This leads even in the case of four-far linkages to some new insights concerning the existence of nodes and cusps. The possible real singularities of non-degenerate coupler curves of the Watt mechanism are determined and by means of our computer program, we demonstrate their difficult structure.

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On Attractive Force Between Electrons In The Same Molecular Orbital, Donald Greenspan Jan 1991

On Attractive Force Between Electrons In The Same Molecular Orbital, Donald Greenspan

Mathematics Technical Papers

Is is assumed, on the basis of recent studies in particle theory, that two electrons in the same molecular orbital attract, rather than repel, and the consequences are explored by means of three dimensional, supercomputer, molecular mechanics type simulations of ground state H2 and D2. Using spectroscopic data, it is shown that, in every case, the resulting vibrational frequency and molecular diameter are entirely in agreement with experiment.

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On Separable Torsion- Free Modules Of Countable Density Character, R. Gobel, Brendan Goldsmith Jan 1991

On Separable Torsion- Free Modules Of Countable Density Character, R. Gobel, Brendan Goldsmith

Articles

The endomorphism algebras of modules of large cardinalities have been extensively studied in recent years using the combinatorial set-theoretic techniques of Shelah-the so-called black-box methods (see, e.g., [4, 5, 151). Despite the spectacular success of these methods, they are not suitable for realization theorems at small carinalities. Of course at the level of countability (or rather more generally for cardinals ~2’~) there are in some cases the original dramatic results of A. L. S. Corner [ 1, 2, 31 and the more recent generalizations of Gobel and May [ 111. Very recently the study of realization problems at cardinalities

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A Comparison Of Ancient Mathematical And Calendrical Systems, Karen Schlauch Jan 1991

A Comparison Of Ancient Mathematical And Calendrical Systems, Karen Schlauch

Masters Theses

No abstract provided.

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When Is Every Order Ideal A Ring Ideal?, Suzanne Larson Jan 1991

When Is Every Order Ideal A Ring Ideal?, Suzanne Larson

Mathematics, Statistics and Data Science Faculty Works

A lattice-ordered ring R is called an OIRI-ring if each of its order ideals is a ring ideal. Generalizing earlier work of Basly and Triki, OIRI-rings are characterized as those f-rings R such that R/I is contained in an f-ring with an identity element that is a strong order unit for some nil l-ideal I of R. In particular, if P(R) denotes the set of nilpotent elements of the f-ring R, then R is an OIRI-ring if and only if R/P(R) is contained in an f-ring with an identity element that is a strong order unit.

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A Fixed Point Property For The Lorentz Space Lp,1(Μ), N L. Carothers, S J. Dilworth, C J. Lennard, D A. Trautman Jan 1991

A Fixed Point Property For The Lorentz Space Lp,1(Μ), N L. Carothers, S J. Dilworth, C J. Lennard, D A. Trautman

Faculty Publications

No abstract provided.

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