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Physical Sciences and Mathematics Commons™

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Selected Works

1991

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

Use Of A Commercially Available Flight Simulator During Aircrew Performance Testing, S. A. Shappell, B. J. Bartosh Oct 1991

Use Of A Commercially Available Flight Simulator During Aircrew Performance Testing, S. A. Shappell, B. J. Bartosh

Scott Shappell

Investigations of aircrew sustained operations (SUSOPS) have been criticized for employing tasks with no apparent
external validity. Because measures obtained directly from aviators flying high-performance aircraft are difficult to
obtain, a laboratory compromise is needed. High-fidelity flight simulators used for aircrew training offer the most
realistic simulation, but their availability is limited. Personal computer-based flight simulators may provide adequate
simulation in, the laboratory at a rea.sonable cost. This report describes a representative research protocol using a
commercially available flight simulator during a simulated aircrew SUSOP.

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The Use Of Kindergarten Screening Scores To Identify The Need For Reading Intervention: A Logit Regression Study, Jayn Crail, John Fraas Sep 1991

The Use Of Kindergarten Screening Scores To Identify The Need For Reading Intervention: A Logit Regression Study, Jayn Crail, John Fraas

John W. Fraas

No abstract provided.

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Handling Constraints In Genetic Algorithms, Cezary Janikow, Zbigniew Michalewicz Jul 1991

Handling Constraints In Genetic Algorithms, Cezary Janikow, Zbigniew Michalewicz

Cezary Janikow

The major difficulty in applicability of genetic algorithms to various optimization problems is the lack of general methodology for handling constraints. This paper discusses a new such methodology and presents results from the experimental system GENOCOP (for GEnetic algorithm for Numerical Optimization for COnstrainted Problems). The system not only handles any objective function with any set of linear constraints, but also effectively reduces the search space. The results indicate that this approach is superior to traditional methods when applied to the nonlinear transportation problem.

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Setting Time Effects On Bentonite Water-Well Annulus Seals, Fred L. Ogden Jun 1991

Setting Time Effects On Bentonite Water-Well Annulus Seals, Fred L. Ogden

Fred L. Ogden

Shear strength tests are conducted in a model of a water well on four, commercially available, granular bentonite well sealing products. The time dependency of annulus seal shear strength and resistance to piping is examined. Dry bentonite samples are placed through water in the annular space between the casing and borehole and allowed to set for a specified time. Pressure is applied at a constant rate to one end of the clay seal until shear or piping failure occurs. Pressure and seal displacement data are recorded on a digital data acquisition system. Annulus seal strength and resistance to piping increase …

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Asymptotic Behavior Of Solutions Of Functionally Perturbed Nonoscillatory Second Order Differential Equations, William F. Trench Dec 1990

Asymptotic Behavior Of Solutions Of Functionally Perturbed Nonoscillatory Second Order Differential Equations, William F. Trench

William F. Trench

No abstract provided.

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Universal Conductivity Curve For A Plane Containing Random Holes., E. J. Garboczi, M. F. Thorpe, M. S. Devries, Anthony Roy Day Dec 1990

Universal Conductivity Curve For A Plane Containing Random Holes., E. J. Garboczi, M. F. Thorpe, M. S. Devries, Anthony Roy Day

Anthony Roy Day

This paper examines the general percolation problem of cutting randomly centered insulating holes in a two-dimensional conducting sheet, and explores how the electrical conductivity sigma decreases with the remaining area fraction. This problem has been studied in the past for circular, square, and needlelike holes, using both computer simulations and analog experiments. In this paper, we extend these studies by examining cases where the insulating hole is of arbitrary shape, using digital-image-based numerical techniques in conjunction with the Y- [nabla] algorithm. We find that, within computational uncertainty, the scaled percolation threshold, xc=nc=5.9±0.4, is a universal quantity for all the cases …

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Review Essay Of Two Books On The History Of Science, Charles Kay Smith Dec 1990

Review Essay Of Two Books On The History Of Science, Charles Kay Smith

Charles Kay Smith

Contrary to what I was taught in high school in the mid-1940s, science is no longer defined as an inductive methodology for immaculately conceiving culture-free truth after sifting through a huge data base of objective facts. For without some prior hypothesis to guide her, a scientist would not be able to decide which facts were relevant. Nowadays hypotheses can come from anywhere in the imagination or culture within which the scientist is working. The importance of a scientific hypothesis is that it be framed in such a way that it can be falsified when tested. Science now has a history …

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