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639 results on '"Stewart, James R."'

163. The physical effects of lightning injury

Author

Epperly, Ted D. and Stewart, James R.

Subjects
Physiological aspects, Analysis, Injuries, Lightning -- Physiological aspects -- Analysis, Heart -- Injuries -- Analysis -- Physiological aspects, Central nervous system -- Injuries -- Analysis -- Physiological aspects, Electrical injuries -- Analysis -- Physiological aspects, Electricity, Injuries from -- Analysis -- Physiological aspects
Abstract

Lightning is a naturally occurring weather-related phenomenon. Estimates reveal that there are approximately 50,000 thunderstorms and 8 million lightning flashes per day that occur worldwide. (1) These estimates suggest that [...]

Published
1989

164. A Navier-Stokes solver for high speed equilibrium flows and application to blunt bodies

Author

Prabhu, Ramadas K, Stewart, James R, and Thareja, Rajiv R

Subjects
Aerodynamics
Abstract

This paper presents a finite element method for the solution of Navier-Stokes equations with the assumption of thermodynamic and chemical equilibrium. The method employs an upwind finite element technique with an implicit time-marching scheme for the solution, and uses an adaptively generated unstructured triangular mesh with several layers of quadrilateral elements near solid walls. The complexity associated with the assumption that the flow is in equilibrium is treated consistently, and the inviscid flux Jacobian matrices are derived. Several problems involving inviscid and viscous hypersonic flow past blunt are solved. Results are compared with other numerical results and experimental data, and generally good agreement is observed.

Published
1989

165. Euler and Navier-Stokes solutions for hypersonic flows

Author

Thareja, Rajiv R, Prabhu, Ramadas K, Stewart, James R, Morgan, Ken, and Peraire, Jaime

Subjects
Aerodynamics
Abstract

An upwind finite-element technique that uses cell-centered quantities and implicit and/or explicit time marching has been developed for computing hypersonic laminar viscous flows using adaptive unstructured grids in two and three dimensions. A perfect gas model as well as an equilibrium air model is implemented for solving high-speed flows. A first-order basic scheme and a higher-order flux-corrected transport (FCT) scheme have been implemented. This technique has been used to predict 'Type III and IV' shock interactions on a cylinder in two dimensions and a swept cylinder in three dimensions, with a view to determine the pressure and heating rate augmentation caused by an impinging shock on the leading edge of a cowl lip of an engine inlet. The predictions of wall pressure and heating rates compare very well with experimental data. The flow features are very distinctly captured with a sequence of adaptively-generated grids. Three-dimensional corner flow, typically encountered in engine inlets due to compression of the flow by ramps in the walls, is also modeled. This procedure is the first step in developing an integrated fluid, thermal, structural analysis capability for hypersonic flight vehicles like the National Aero-Space Plane.

Published
1989

166. A point implicit unstructured grid solver for the Euler and Navier-Stokes equations

Author

Thareja, Rajiv R, Stewart, James R, Hassan, Obey, Morgan, Ken, and Peraire, Jaime

Subjects
Fluid Mechanics And Heat Transfer
Abstract

An upwind finite element technique that uses cell centered quantities and implicit and/or explicit time marching has been developed for computing hypersonic laminar viscous flows using adaptive unstructured triangular grids. A structured grid of quadrilaterals is laid out near the body surface. For inviscid flows the method is stable at Courant numbers of over 100,000. A first order basic scheme and a higher order flux corrected transport (FCT) scheme have been implemented. This technique has been applied to the problem of predicting type III and IV shock wave interactions on a cylinder, with a view of simulating the pressure and heating rate augmentation caused by an impinging shock on the leading edge of a cowl lip of an engine inlet. The predictions of wall pressure and heating rates compare very well with experimental data. The flow features are very distinctly captured with a sequence of adaptively generated grids. The adaptive mesh generator and the upwind Navier-Stokes solver are combined in a set of programs called LARCNESS, an acronym for Langley Adaptive Remeshing Code and Navier-Stokes Solver.

Published
1988

167. Application of finite element and remeshing technique to shock interference on a cylindrical leading edge

Author

Stewart, James R, Thareja, Rajiv R, Wieting, Allan R, and Morgan, Ken

Subjects
Aerodynamics
Abstract

The problem of planar oblique shock impingement on a cylindrical leading edge in hypersonic flow is modeled using a Galerkin-Runge Kutta finite element method. The method utilizes a four stage Runge-Kutta time stepping scheme to solve the compressible Euler equations. Freestream Mach numbers of 6.5, 8.0 and 16.0 are studied. The computed surface pressure distributions consistently agree well with available experimental data. The peak pressure amplification ranges from 5.45 at M = 6.5 to approximately 17.0 at M = 16.0. Stagnation point heat transfer rate amplifications are calculated from the inviscid solution using the method of Fay and Riddell. The value and wall location of the peak pressure and heat transfer rate amplifications are extremely sensitive to the location of the impinging shock/bow shock intersection point.

Published
1988

182. Assessment of United States Army Environmental Quality Research, Development, and Acquisition (EQ RDA). Application of Opportunities from Defense and Army Acquisition Reforms.

Author

ARMY WAR COLL CARLISLE BARRACKS PA, Stewart, James R., ARMY WAR COLL CARLISLE BARRACKS PA, and Stewart, James R.

Abstract

Over the next six years the Army expects to pay more than $8.7 billion dollars to remediate contaminated lands and to mitigate outdated industrial and troop installation operations. These high costs have had and will continue to have significant impact on the availability of resources for operations, modernization and procurement of critical warfighting materiel, and training lands. Environmental costs therefore represent significant opportunity losses for Army Readiness. The Secretary of the Army and the Chief of Staff of the Army promulgated the 'Army's Environmental Strategy into the 21st Century' to drive environmental sustainability as a tool for maintaining Army Readiness. However, serious limitations of available environmental technologies are hampering that Strategy. The Army has invested substantially in environmental quality research, development, and acquisition (EQ RDA) to modernize its environmental technologies. Unfortunately, that effort has had little strategic pay-off and the Army remains far from reaching its goal of environmental sustainability. This study represents a comprehensive assessment of the management practices the Army has used in the past to conduct EQ RDA. It contains the perspectives of key stakeholder elements of the Army Secretariat and Army Staff. Additionally, conclusions draw on the expertise available in the Tri-Service EQ RDA arena, the Defense Acquisition University, and the Office of the Deputy Undersecretary of Defense for Environmental Security. Several useful management tools proven highly effective in Defense and Army Systems RDA programs are recommended for EQ RDA implementation. These tools will ensure greater returns on Army R&D investments and facilitate meeting Army sustainability goals.

Published
1996

186. Earthquake rumblings

Author

Stewart, James R., Jr.

Subjects
Science and technology
Abstract

I reviewed this very interesting story ('Seismologists in a rumble over quake clusters,' SN.. 5/7/11, p. 5) this morning, and it occurred to me that the connection between all of [...]

Published
2011

190. Pharmacokinetics and Pharmacodynamics of Oximes in Unanesthetized Pigs

Author

ARMY MEDICAL RESEARCH INST OF CHEMICAL DEFENSE ABERDEEN PROVING GROUND MD, Stemler, Fred W., Tezak-Reid, Theresa M., McCluskey, Michael P., Kaminskis, Andris, Corcoran, Kevin D., Shih, Ming L., Stewart, James R., ARMY MEDICAL RESEARCH INST OF CHEMICAL DEFENSE ABERDEEN PROVING GROUND MD, Stemler, Fred W., Tezak-Reid, Theresa M., McCluskey, Michael P., Kaminskis, Andris, Corcoran, Kevin D., Shih, Ming L., and Stewart, James R.

Abstract

The pharmacokinetics and cardiovascular pharmacodynamics of three oximes were studied in unanesthetized pigs. Cardiopulmonary parameters were monitored and plasma concentrations of oximes were determined from arterial blood samples taken at intervals over a period of 5 hr postinjection. Plasma concentrations for all oximes were fitted to standard pharmacokinetic models using the computer program PCNONLIN. Average pharmacokinetic parameters were determined for each oxime. Only mild to moderate physiological side effects were detected following intramuscular administration. 2-PAM C1 and ICD 467 were both more rapidly absorbed, with slightly faster distribution and elimination rates for ICD 467. Although MMB-4 had a slight lag time to attain detectable levels in the blood, retention time was longer than for 2-PAM C1 and ICD 467.

Published
1991

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