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At least 1,081 records · Page 60
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NASA NTRS1993

Cape Photographic Durchmusterung, volume 1

The Cape Photographic Durchmusterung (CPD Gill and Kapteyn 1895-1900) is a photographic survey of southern stars in the declination range -18 to -90 degrees. This volume covers the declination range -18 through -37 degrees. Positions are given for the 1875 equinox. The summary of the positional uncertainties quoted in the third volume of the published catalog gives +/- 0.28 sec (R.A.) +/- 0.044 arcmin (Dec.) for zones -18 to -57 degrees. The probable error of a photographic magnitude as determined by combining results for different magnitudes and weighting proportionately according to the numbers of stars in each class of magnitude is given as +/- 0.055 mag. From an analysis of the taint magnitude limits on the plates discussed in the third volume introduction, the catalog as a whole can be considered complete to photographic magnitude 9.2 but it is stated that it will be found practically complete in or near the Milky Way, to magnitude 9.5.

Source record↗
NASA NTRS1993

Some implementational issues of convection schemes for finite volume formulations

Two higher-order upwind schemes - second-order upwind and QUICK - are examined in terms of their interpretation, implementation as well as performance for a recirculating flow in a lid-driven cavity, in the context of a control volume formulation using the SIMPLE algorithm. The present formulation of these schemes is based on a unified framework wherein the first-order upwind scheme is chosen as the basis, with the remaining terms being assigned to the source term. The performance of these schemes is contrasted with the first-order upwind and second-order central difference schemes. Also addressed in this study is the issue of boundary treatment associated with these higher-order upwind schemes. Two different boundary treatments - one that uses a two-point scheme consistently within a given control volume at the boundary, and the other that maintains consistency of flux across the interior face between the adjacent control volumes - are formulated and evaluated.

Thakur, Siddharth↗
NASA NTRS1993

Some implementational issues of convection schemes for finite-volume formulations

Two higher-order upwind schemes - second-order upwind and QUICK - are examined in terms of their interpretation, implementations, as well as performance for a recirculating flow in a lid-driven cavity, in the context of a control-volume formulation using the SIMPLE algorithm. The present formulation of these schemes is based on a unified framework wherein the first-order upwind scheme is chosen as the basis, with the remaining terms being assigned to the source term. The performance of these schemes is contrasted with the first-order upwind and second-order central difference schemes. Also addressed in this study is the issue of boundary treatment associated with these higher-order upwind schemes. Two different boundary treatments - one that uses a two-point scheme consistently within a given control volume at the boundary, and the other that maintains consistency of flux across the interior face between the adjacent control volumes - are formulated and evaluated.

Thakur, Siddharth↗
NASA NTRS1994

Measuring Intracranial Pressure And Volume Noninvasively

Ultrasonic technique eliminates need to drill into brain cavity. Intracranial dynamics instrument probes cranium ultrasonically to obtain data for determination of intracranial pressure (ICP) and pressure-volume index (PVI). Instrument determines sensitivity of skull to changes in pressure and by use of mechanical device to exert external calibrated pressure on skull. By monitoring volume of blood flowing into jugular vein, one determines change of volume of blood in cranial system. By measuring response of skull to increasing pressure (where pressure increased by tilting patient known amount) and by using cranial blood pressure, one determines intial pressure in cerebrospinal fluid. Once PVI determined, ICP determined.

Cantrell, John H.↗
NASA NTRS1992

Summaries of the Third Annual JPL Airborne Geoscience Workshop. Volume 2: TIMS Workshop

This publication contains the preliminary agenda and summaries for the Third Annual JPL Airborne Geoscience Workshop, held at the Jet Propulsion Laboratory, Pasadena, California, on 1-5 June 1992. This main workshop is divided into three smaller workshops as follows: (1) the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on June 1 and 2; the summaries for this workshop appear in Volume 1; (2) the Thermal Infrared Multispectral Scanner (TIMS) workshop, on June 3; the summaries for this workshop appear in Volume 2; and (3) the Airborne Synthetic Aperture Radar (AIRSAR) workshop, on June 4 and 5; the summaries for this workshop appear in Volume 3.

Realmuto, Vincent J.↗
NASA NTRS1992

Summaries of the Third Annual JPL Airborne Geoscience Workshop. Volume 3: AIRSAR Workshop

This publication contains the preliminary agenda and summaries for the Third Annual JPL Airborne Geoscience Workshop, held at the Jet Propulsion Laboratory, Pasadena, California, on 1-5 June 1992. This main workshop is divided into three smaller workshops as follows: (1) the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) workshop, on June 1 and 2; the summaries for this workshop appear in Volume 1; (2) the Thermal Infrared Multispectral Scanner (TIMS) workshop, on June 3; the summaries for this workshop appear in Volume 2; and (3) the Airborne Synthetic Aperture Radar (AIRSAR) workshop, on June 4 and 5; the summaries for this workshop appear in Volume 3.

Vanzyl, Jakob↗
NASA NTRS1993

Parallel runway requirement analysis study. Volume 2: Simulation manual

This document is a user manual for operating the PLAND_BLUNDER (PLB) simulation program. This simulation is based on two aircraft approaching parallel runways independently and using parallel Instrument Landing System (ILS) equipment during Instrument Meteorological Conditions (IMC). If an aircraft should deviate from its assigned localizer course toward the opposite runway, this constitutes a blunder which could endanger the aircraft on the adjacent path. The worst case scenario would be if the blundering aircraft were unable to recover and continue toward the adjacent runway. PLAND_BLUNDER is a Monte Carlo-type simulation which employs the events and aircraft positioning during such a blunder situation. The model simulates two aircraft performing parallel ILS approaches using Instrument Flight Rules (IFR) or visual procedures. PLB uses a simple movement model and control law in three dimensions (X, Y, Z). The parameters of the simulation inputs and outputs are defined in this document along with a sample of the statistical analysis. This document is the second volume of a two volume set. Volume 1 is a description of the application of the PLB to the analysis of close parallel runway operations.

Ebrahimi, Yaghoob S.↗
NASA NTRS1993

Satellite communications systems and technology. Volume 2: Site reports

This is volume 2 of the final report of the NASA/NSF Panel on Satellite Communications Systems and Technology. It consists of the site reports from the panel's visits to satellite communications facilities and laboratories in Europe, Japan, and Russia. The Executive Summary of the panel's final report is published separately. Volume 1, also published separately, consists of the panel's analytical chapters. Information on ordering the Executive Summary and Volume 1 from the National Technical Information Service is included.

Edelson, Burton I.↗
NASA NTRS1993

Flex bearing UUEC, volume 2

This volume, Volume 2, of this Flex Bearing UUEC Final Report documents findings and data pertaining to Team B's tasks. Team B was organized as one of two sub-teams of the Unplanned/Unintended Event or Condition (UUEC) board established per InterOffice Memorandum (IOM) A100-FY93-072. Team A determined the cause of the unacceptable unbonds (referred to as 'heat-affect' unbonds), including the initial, light rust film, in the FSM #3 flex bearing was overheating of the Forward End Ring (FER) during cure, specifically in zone 8 of the mold. Team A's findings are documented in Volume 1 of this report. Team B developed flight rationale for existing bearings, based on absence or presence of an unpropitious unbond condition like that in FSM #3's flex bearing.

Clapper, M. L.↗
NASA NTRS1994

Plasma volume shifts and exercise thermoregulation with water immersion and six-degree head-down tilt

The hypothesized fluid shifts and resultant responses that occur during spaceflight are simulated by six-degree head down tilt (HDT) and water immersion (WI). The purpose of this study was to compare exercise thermoregulation before and after physiologic mechanisms reduce plasma volume (PV) in response to 24-hr HDT (HDT24). A secondary study utilized WI to reproduce the PV reduction of HDT24. Seven males were studied in two conditions: during 70 minutes of supine cycling ergometry at 58 percent of peak oxygen consumption following 1-hr HDT (HDT1) and HDT24; and up to 6 hr WI at 34.5 C. Plasma volume was reduced by 10.4 percent in HDT24 when compared to HDT1. Pre-exercise rectal temperature, T(sub re), was an average 0.22 C higher after HDT24. Rectal temperature increased during exercise with no interaction between time and treatment. The reduced PV and elevated pre-exercise T(sub re) had offsetting effects on thermoregulatory mechanisms, suggesting no alteration in the response at a given T(sub re). Plasma volume was reduced by 4.3 +/- 2.3 percent and 1.1 +/- 1.8 percent following HDT24 and WI, respectively, compared to upright chair rest. Although the reductions in PV were not significantly different, great intra-individual variability was evident. The ability to reproduce PV changes consistently with HDT and WI is limited by this variability.

Ertl, Andrew Carl↗
NASA NTRS1993

Volume server: A scalable high speed and high capacity magnetic tape archive architecture with concurrent multi-host access

A major challenge facing data processing centers today is data management. This includes the storage of large volumes of data and access to it. Current media storage for large data volumes is typically off line and frequently off site in warehouses. Access to data archived in this fashion can be subject to long delays, errors in media selection and retrieval, and even loss of data through misplacement or damage to the media. Similarly, designers responsible for architecting systems capable of continuous high-speed recording of large volumes of digital data are faced with the challenge of identifying technologies and configurations that meet their requirements. Past approaches have tended to evaluate the combination of the fastest tape recorders with the highest capacity tape media and then to compromise technology selection as a consequence of cost. This paper discusses an architecture that addresses both of these challenges and proposes a cost effective solution based on robots, high speed helical scan tape drives, and large-capacity media.

Rybczynski, Fred↗
NASA NTRS1993

An arbitrary grid CFD algorithm for configuration aerodynamics analysis. Volume 1: Theory and validations

This report documents the user input and output data requirements for the FEMNAS finite element Navier-Stokes code for real-gas simulations of external aerodynamics flowfields. This code was developed for the configuration aerodynamics branch of NASA ARC, under SBIR Phase 2 contract NAS2-124568 by Computational Mechanics Corporation (COMCO). This report is in two volumes. Volume 1 contains the theory for the derived finite element algorithm and describes the test cases used to validate the computer program described in the Volume 2 user guide.

Baker, A. J.↗
NASA NTRS1992

An arbitrary grid CFD algorithm for configuration aerodynamics analysis. Volume 2: FEMNAS user guide

This report documents the user input and output data requirements for the FEMNAS finite element Navier-Stokes code for real-gas simulations of external aerodynamics flowfields. This code was developed for the configuration aerodynamics branch of NASA ARC, under SBIR Phase 2 contract NAS2-124568 by Computational Mechanics Corporation (COMCO). This report is in two volumes. Volume 1 contains the theory for the derived finite element algorithm and describes the test cases used to validate the computer program described in the Volume 2 user guide.

Manhardt, Paul D.↗
NASA NTRS1994

A Selection of Experimental Test Cases for the Validation of CFD Codes, Volume 2

This report presents the results of a study by Working Group 14 of the AGARD Fluid Dynamics Panel. The thirty nine test cases that are documented cover the subsonic, transonic, and supersonic flow regimes and five classes of geometries. Included in the five classes of geometries are: Two Dimensional Airfoils; Three Dimensional Wings, designed for predominantly attached flow conditions; Slender Bodies, typical of missile type configurations; Delta Wings, characterized by a conical type of vortex flow; and Complex Configurations, either in a geometrical sense or because of complicated flow interactions. The report is presented in two volumes. Volume 1 provides a review of the theoretical and experimental requirements, a general introduction, summary of the test cases and recommendations for the future. Volume 2 contains detailed information on the test cases.

Advisory Group for Aerospace Research and Developm↗
NASA NTRS1995

A preliminary comparison of Landsat Thematic Mapper and SPOT-1 HRV multispectral data for estimating coniferous forest volume

Digital Landsat Thematic Mapper (TM) and Satellite Probatoire d'Observation de la Terre (SPOT) High Resolution Visible (HRV) images of coniferous forest canopies were compared in their relationship to forest wood volume using correlation and regression analyses. Significant inverse relationships were found between softwood volume and the spectral bands from both sensors (P less than 0.01). The highest correlations were between the log of softwood volume and the near-infrared bands (HRV band 3, r = -0.89; TM band 4, r = -0.83).

Ripple, William J.↗
NASA NTRS1994

BSM Delta Qualification 2, volume 3, book 2

This report, presented in three volumes, provides the results of a two-motor Delta Qualification 2 program conducted in 1993 to certify the following enhancements for incorporation into booster separation motor (BSM0 flight hardware: vulcanized-in-place nozzle aft closure insulation; new iso-static ATJ bulk graphite throat insert material, adhesive EA9394 for bonding the nozzle throat, igniter grain rod/centering insert/igniter case; deletion of the igniter adapter insulator ring; deletion of the igniter adapter/igniter case interface RTV; and deletion of loctite from igniter retainer plate threads. The enhancements above directly resulted from (1) the BSM total quality management (TQM) team initiatives to enhance the BSM producibility, and (2) the necessity to qualify new throat insert and adhesive systems to replace existing materials that will not be available. Testing was completed at both the component and motor levels. Component testing was accomplished to screen candidate materials (e.g., throat materials, adhesive systems) and to optimize processes (e.g., aft closure insulator vulcanization approach) prior to their incorporation into the test motors. Motor testing--consisting of two motors, randomly selected by USBI's on-site quality personnel from production lot AAY, which were modified to accept the enhancements -- was completed to provide the final qualification of the enhancements for incorporation into flight hardware. Volume 3, Book 2 provides various supporting documentation to the previous volumes with regards to the testing of the two Delta qualification units: data acceptance records, thermal conditioning analysis, igniter adapter thermal flake analysis, laboratory adhesive (EA-9394) qualification report, throat insert thermal/structural analysis, Delta Qualification Nonconformance Reports (NCR's), O-ring seating tests, and interim test report for vulcanization process qualification.

Source record↗
NASA NTRS1995

Category 5 problem solution using an unstructured finite volume algorithm

For the simulation of flows with complex geometries, unstructured finite volume methods have proven to be very popular, and simulations of a large number of flows have been done with good results using this approach. Since most of the simulations to date were done for steady flows, it is not clear that present unstructured finite volume algorithms can accurately track the unsteady propagation of acoustic waves in a computation. Therefore, there is a need to assess the accuracy of these methods for acoustic calculations. In this paper, we perform the numerical simulation of a very small amplitude acoustic wave incident on the non-uniform steady flow in a quasi- 1 D convergent-divergent nozzle using an unstructured finite volume algorithm with piece-wise linear, least square reconstruction, Roe flux difference splitting, and second-order MacCormack time marching. First, the spatial accuracy of the algorithm is evaluated for the steady flow by running the simulation with a sequence of successively finer meshes. Then the unsteady numerical solution with the acoustic perturbation is presented.

Bui, Trong T.↗