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in creator/contributor: "Hansen, C."

open access

New stringer for the LAMPF radiation effects facility

New stringer design, allowing access to the spallation neutron flux at the Clinton P. Anderson Meson Physics Facility (LAMPF) beam stop is described, together with information on the neutron spectrum.

Date: January 1, 1981

Creator: Brown, R. D. & Hansen, C. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Geometric optimization

An algorithm is presented which describes an application independent method for reducing the number of polygonal primitives required to faithfully represent an object. Reducing polygon count without a corresponding reduction in object detail is important for: achieving interactive frame rates in scientific visualization, reducing mass storage requirements, and facilitating the transmission of large, multi-timestep geometric data sets. This paper shows how coplanar and nearly coplanar polygons c… more

Date: September 1, 1993

Creator: Hinker, P. & Hansen, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The erosion of meteors and high-speed vehicles in the upper atmosphere

From Summary: "A simple inelastic collision model of meteor-atmosphere interaction is used and analytic relations for velocity, deceleration, size, and relative luminous magnitude of meteors are derived and expressed in dimensionless parametric form. The analysis is compared with available quantitative observations of meteor behavior and it is indicated that a large fraction of the atmospheric bombardment energy is used in eroding meteor material. The erosion from large, high-speed vehicles as … more

Date: March 1957

Creator: Hansen, C. Frederick

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Approximations for the thermodynamic and transport properties of high-temperature air

Report presenting the thermodynamic and transport properties of high-temperature air in closed form starting from approximate partition functions for the major components in air and neglecting all minor components. The compressibility, energy, entropy, specific heats, speed of sound, coefficients of viscosity and thermal conductivity, and Prandtl numbers for air are provided for a range of temperatures and pressures.

Date: March 1958

Creator: Hansen, C. Frederick

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Frame work on an on-line regulations expert permit server, Semi-annual technical progress report, September 25, 1996--March 24, 1997

The Interstate Oil and Gas Compact Commission and its member states have become increasingly concerned about environmental compliance costs for the petroleum exploration and production industry with estimated costs for 1990 at about $2 billion. Over the last decade, these costs have increased at a rate of 3 to 5% per year. At a time when regulatory and environmental needs and costs are increasing, major oil companies are restructuring and reducing staffs. The places an increased burden on the r… more

Date: March 24, 1997

Creator: Hansen, C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Investigation of a rotary valving system with variable valve timing for internal combustion engines: Final technical report

The objective of the program was to provide a functional demonstration of the Hansen Rotary Valving System with Variable Valve timing (HRVS/VVT), capable of throttleless inlet charge control, as an alternative to conventional poppet-valves for use in spark ignited internal combustion engines. The goal of this new technology is to secure benefits in fuel economy, broadened torque band, vibration reduction, and overhaul accessibility. Additionally, use of the variable valve timing capability to v… more

Date: November 18, 1994

Creator: Cross, P. C. & Hansen, C. N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Fast stereoscopic images with ray-traced volume rendering

One of the drawbacks of standard volume rendering techniques is that is it often difficult to comprehend the three-dimensional structure of the volume from a single frame; this is especially true in cases where there is no solid surface. Generally, several frames must be generated and viewed sequentially, using motion parallax to relay depth. Another option is to generate a single spectroscopic pair, resulting in clear and unambiguous depth information in both static and moving images. Methods … more

Date: May 1, 1994

Creator: Adelson, S. J. & Hansen, C. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Visualization on massively parallel computers using CM/AVS

CM/AVS is a visualization environment for the massively parallel CM-5 from Thinking Machines. It provides a backend to the standard commercially available AVS visualization product. At the Advanced Computing Laboratory at Los Alamos National Laboratory, we have been experimenting and utilizing this software within our visualization environment. This paper describes our experiences with CM/AVS. The conclusions reached are applicable to any implimentation of visualization software within a massiv… more

Date: September 1, 1993

Creator: Krogh, M. F. & Hansen, C. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fast data parallel polygon rendering

This paper describes a parallel method for polygonal rendering on a massively parallel SIMD machine. This method, based on a simple shading model, is targeted for applications which require very fast polygon rendering for extremely large sets of polygons such as is found in many scientific visualization applications. The algorithms described in this paper are incorporated into a library of 3D graphics routines written for the Connection Machine. The routines are implemented on both the CM-200 a… more

Date: September 1, 1993

Creator: Ortega, F. A. & Hansen, C. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Parallel sphere rendering

Sphere rendering is an important method for visualizing molecular dynamics data. This paper presents a parallel algorithm that is almost 90 times faster than current graphics workstations. To render extremely large data sets and large images, the algorithm uses the MIMD features of the supercomputers to divide up the data, render independent partial images, and then finally composite the multiple partial images using an optimal method. The algorithm and performance results are presented for the… more

Date: October 1, 1996

Creator: Krogh, M.; Painter, J. & Hansen, C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Cost-effective data-parallel load balancing

Load balancing algorithms improve a program`s performance on unbalanced datasets, but can degrade performance on balanced datasets, because unnecessary load redistributions occur. This paper presents a cost-effective data-parallel load balancing algorithm which performs load redistributions only when the possible savings outweigh the redistribution costs. Experiments with a data-parallel polygon renderer show a performance improvement of up to a factor of 33 on unbalanced datasets and a maximum… more

Date: May 1, 1995

Creator: Hansen, C. D. & Ahrens, J. P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Parallel rendering techniques for massively parallel visualization

As the resolution of simulation models increases, scientific visualization algorithms which take advantage of the large memory. and parallelism of Massively Parallel Processors (MPPs) are becoming increasingly important. For large applications rendering on the MPP tends to be preferable to rendering on a graphics workstation due to the MPP`s abundant resources: memory, disk, and numerous processors. The challenge becomes developing algorithms that can exploit these resources while minimizing ov… more

Date: July 1, 1995

Creator: Hansen, C.; Krogh, M. & Painter, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Condensation of air in supersonic wind tunnels and its effects on flow about models

Report presenting the results of an investigation of condensation phenomena in supersonic wind tunnel. Lower and upper limits for the degree of supersaturation attainable before the onset of condensation of air are discussed. A method is presented for calculating the properties of a stream containing a small fraction of condensed air.

Date: April 1952

Creator: Hansen, C. Frederick & Nothwang, George J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A review of the thermodynamic, transport, and chemical reaction rate properties of high-temperature air

Thermodynamic and transport properties of high temperature air, and the reaction rates for the important chemical processes which occur in air, are reviewed. Semiempirical, analytic expressions are presented for thermodynamic and transport properties of air. Examples are given illustrating the use of these properties to evaluate (1) equilibrium conditions following shock waves, (2) stagnation region heat flux to a blunt high-speed body, and (3) some chemical relaxation lengths in stagnation reg… more

Date: July 1958

Creator: Hansen, C. Frederick & Heims, Steve P.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

X-Ray Instrumentation for Density Measurements in a Supersonic Flow Field

Report describing an instrument based on the principle that an x-ray beam is essentially undeviated while traversing a short path in air. It was used to measure the product of air density and the path length in the 10- by 14-inch supersonic wind tunnel. The measurements obtained were accomplished by comparing the intensity of two beams from the same X-ray source.

Date: December 1952

Creator: Dimeff, John; Hallett, Ralph K., Jr. & Hansen, C. Frederick

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Case study of isosurface extraction algorithm performance

Isosurface extraction is an important and useful visualization method. Over the past ten years, the field has seen numerous isosurface techniques published leaving the user in a quandary about which one should be used. Some papers have published complexity analysis of the techniques yet empirical evidence comparing different methods is lacking. This case study presents a comparative study of several representative isosurface extraction algorithms. It reports and analyzes empirical measurements … more

Date: December 14, 1999

Creator: Sutton, P M; Hansen, C D; Shen, H & Schikore, D

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Parallel sphere rendering

Sphere rendering is an important method for visualizing molecular dynamics data. This paper presents a parallel divide-and-conquer algorithm that is almost 90 times faster than current graphics workstations. To render extremely large data sets and large images, the algorithm uses the MIMD features of the supercomputers to divide up the data, render independent partial images, and then finally composite the multiple partial images using an optimal method. The algorithm and performance results ar… more

Date: May 1, 1995

Creator: Krogh, M.; Hansen, C.; Painter, J. & de Verdiere, G.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Photon burst mass spectrometry for the measurement of {sup 85}Kr at ambient levels

Photon Burst Mass Spectrometry has been used to measure {sup 85}Kr in a sample with an abundance of 6 x 10{sup {minus}9}. Improvements in detection efficiency by the use of avalanche photodiodes cooled to liquid nitrogen temperature are reported, which should make possible measurement of {sup 85}Kr at the ambient atmospheric abundance of 10{sup {minus}11}. Potential applications include nuclear monitoring, atmospheric transport, and dating young ground water up to 40 years.

Date: December 1, 1998

Creator: Fairbank, W. M., Jr.; LaBelle, R.D. & Hansen, C.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Stagnation-point heat transfer to blunt shapes in hypersonic flight, including effects of yaw

An approximate theory is developed for predicting the rate of heat transfer to the stagnation region of blunt bodies in hypersonic flight. Attention is focused on the case where wall temperature is small compared to stagnation temperature. The theoretical heat-transfer rate at the stagnation point of a hemispherical body is found to agree with available experimental data. The effect of yaw on heat transfer to a cylindrical stagnation region is treated at some length, and it is predicted that la… more

Date: April 1958

Creator: Eggers, A. J., Jr.; Hansen, C. Frederick & Cunningham, Bernard E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Theoretical and Experimental Investigation of the Effect of Yaw on Heat Transfer to Circular Cylinders in Hypersonic Flow

Report presenting an approximate theory for predicting the rate of heat transfer to the stagnation region of blunt bodies in hypersonic flight. Attention is focused on the case where wall temperature is small compared to stagnation temperature. Experiments were conducted in the hypersonic gun tunnel to obtain a preliminary check on this theoretical prediction.

Date: July 25, 1955

Creator: Eggers, A. J., Jr.; Hansen, C. Frederick & Cunningham, Bernard E.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

A data distributed, parallel algorithm for ray-traced volume rendering

This paper presents a divide-and-conquer ray-traced volume rendering algorithm and its implementation on networked workstations and a massively parallel computer, the Connection Machine CM-5. This algorithm distributes the data and the computational load to individual processing units to achieve fast, high-quality rendering of high-resolution data, even when only a modest amount of memory is available on each machine. The volume data, once distributed, is left intact. The processing nodes perfo… more

Date: March 30, 1993

Creator: Ma, Kwan-Liu; Painter, J. S.; Hansen, C. D. & Krogh, M. F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ACLMPL: Portable and efficient message passing for MPPs

This paper presents the Advanced Computing Lab Message Passing Library (ACLMPL). Modeled after Thinking Machines Corporation`s CMMD, ACLMPL is a high throughout, low latency communications library for building message passing applications. The library has been implemented on the Cray T3D, Thinking Machines CM-5, SGI workstations, and on top of PVM. On the Cray T3D, benchmarks show ACLMPL to be 4 to 7 times faster than MPI or PVM.

Date: September 19, 1995

Creator: Painter, J.; Krogh, M.; Hansen, C.; McCormick, P. & de Verdiere, G.C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The ACL Message Passing Library

This paper presents the ACL (Advanced Computing Lab) Message Passing Library. It is a high throughput, low latency communications library, based on Thinking Machines Corp.`s CMMD, upon which message passing applications can be built. The library has been implemented on the Cray T3D, Thinking Machines CM-5, SGI workstations, and on top of PVM.

Date: September 1, 1995

Creator: Painter, J.; McCormick, P.; Krogh, M.; Hansen, C. & Colin de Verdiere, G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Pulsations of the R Coronae Borealis Stars

The radial pulsations of very luminous, low-mass models (L/M approx. 10/sup 4/, solar units), which are possible representatives of the R CrB stars, have been examined. These pulsations are extremely nonadiabatic. There are in some cases at least one extra (strange) mode which makes interpretation difficult. The blue instability edges are also peculiar, in that there is an abrupt excursion of the blue edge to the blue for L/M sufficiently large. The range of periods of the model encompasses obs… more

Date: January 1, 1980

Creator: Cox, J. P.; King, D. S.; Cox, A. N.; Wheeler, J. C.; Hansen, C. J. & Hodson, S. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department