SEARCH · Search NASA

Results for “performance verification”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12

All sources NASA NTRS DOE OSTI

NASA NTRS1992

Rapid development of the X-31 simulation to support flight-testing

The X-31 Enhanced Fighter Maneuverability Program has been recognized to form the International Test Organization, with the NASA Dryden Flight Research Facility (NASA-Dryden) as the responsible test organization. The two X-31 research aircraft and engineering support personnel were colocated at NASA-Dryden, with flight test operations beginning in Apr. 1992. Therefore, rapid development of a hardware-in-the-loop simulation was needed to support the flight test operations at NASA-Dryden, and to perform verification and validation of flight control software. The X-31 simulation system requirements, distributed simulation system architecture, simulation components math models to the visual system, and the advanced capabilities the X-31 simulation provides. In addition, unique software tools and the methods used to rapidly develop this simulation system will be highlighted.

Mackall, Dale↗

NASA NTRS1992

Rapid development of the X-31 simulation to support flight-testing

Mackall, Dale↗

NASA NTRS1993

Concept report: Experimental vector magnetograph (EXVM) operational configuration balloon flight assembly

The observational limitations of earth bound solar studies has prompted a great deal of interest in recent months in being able to gain new scientific perspectives through, what should prove to be, relatively low cost flight of the magnetograph system. The ground work done by TBE for the solar balloon missions (originally planned for SOUP and GRID) as well as the rather advanced state of assembly of the EXVM has allowed the quick formulation of a mission concept for the 30 cm system currently being assembled. The flight system operational configuration will be discussed as it is proposed for short duration flight (on the order of one day) over the continental United States. Balloon hardware design requirements used in formulation of the concept are those set by the National Science Balloon Facility (NSBF), the support agency under NASA contract for flight services. The concept assumes that the flight hardware assembly would come together from three development sources: the scientific investigator package, the integration contractor package, and the NSBF support system. The majority of these three separate packages can be independently developed; however, the computer control interfaces and telemetry links would require extensive preplanning and coordination. A special section of this study deals with definition of a dedicated telemetry link to be provided by the integration contractor for video image data for pointing system performance verification. In this study the approach has been to capitalize to the maximum extent possible on existing hardware and system design. This is the most prudent step that can be taken to reduce eventual program cost for long duration flights. By fielding the existing EXVM as quickly as possible, experience could be gained from several short duration flight tests before it became necessary to commit to major upgrades for long duration flights of this system or of the larger 60 cm version being considered for eventual development.

Source record↗

NASA NTRS1994

Potential capabilities of Reynolds stress turbulence model in the COMMIX-RSM code

A Reynolds stress turbulence model has been implemented in the COMMIX code, together with transport equations describing turbulent heat fluxes, variance of temperature fluctuations, and dissipation of turbulence kinetic energy. The model has been verified partially by simulating homogeneous turbulent shear flow, and stable and unstable stratified shear flows with strong buoyancy-suppressing or enhancing turbulence. This article outlines the model, explains the verifications performed thus far, and discusses potential applications of the COMMIX-RSM code in several domains, including, but not limited to, analysis of thermal striping in engineering systems, simulation of turbulence in combustors, and predictions of bubbly and particulate flows.

Chang, F. C.↗

NASA NTRS1994

Cascaded clocks measurement and simulation findings

This paper will examine aspects related to network synchronization distribution and the cascading of timing elements. Methods of timing distribution have become a much debated topic in standards forums and among network service providers (both domestically and internationally). Essentially these concerns focus on the need to migrate their existing network synchronization plans (and capabilities) to those required for the next generation of transport technologies (namely, the Synchronous Digital Hierarchy (SDH), Synchronous Optical Networks (SONET), and Asynchronous Transfer Mode (ATM). The particular choices for synchronization distribution network architectures are now being evaluated and are demonstrating that they can indeed have a profound effect on the overall service performance levels that will be delivered to the customer. The salient aspects of these concerns reduce to the following: (1) identifying that the devil is in the details of the timing element specifications and the distribution of timing information (i.e., small design choices can have a large performance impact); (2) developing a standardized method of performance verification that will yield unambiguous results; and (3) presentation of those results. Specifically, this will be done for two general cases: an ideal input, and a noisy input to a cascaded chain of slave clocks.

Chislow, Don↗

NASA NTRS1994

Marshall Space Flight Center head development program

This report summarizes the results of the candidate head evaluation for the new long-life magnetic head per the SOW of Contract No. NAS8-39407, MSFC Head Development Program. The original program plans were to test a candidate head, fabricate a new head, then qualify the new head. These activities were scheduled to be carried out between March 1993 and March 1994. The program was halted after the evaluation of the candidate head by NAS8-39407 Amendment No. 4. MSFC has provided and authorized the use the MARS-2000 SRB QUAL Recorder PN 10400-0677-801 - Serial Number 200004 (Datatape PN 591000 - Serial Number 1004), Reproduce Amplifier Module (RAM) Datatape PN 533040 - Serial Number 2006, associated cables, and magnetic tape on special SRB/DFI tapered reels to Datatape for this program. All the testing that has been done for the candidate head evaluation was done at Datatape's facility in Pasadena,CA. The testing was performed in a Class 100,000 particle counts clean room at ambient temperature, except for the thermal testing which was conducted in a different area at Datatape. The Performance Verification Test Procedure PVT-11004-4 (PVT) and Acceptance Test Procedure ATP-11004-09 (ATP) procedures were used when tests were conducted on the recorder.

Harrer, Jim↗

NASA NTRS1994

New X-ray spectral observations of NGC 4151 with ASCA

We present new X-ray spectral data for the well-studied Seyfert galaxy NGC 4151, which was observed twice for about 20 ks each during the ASCA performance verification phase, once on 1993 May 25 and again on 1993 November 5. The source underwent complex spectral variability, and the observed 2-10 keV flux increased by a factor of 2 while the intrinsic 2-10 keV flux increased by no more than 20%. The data can be modeled with either a dual cold absorber plus a soft X-ray excess consisting of scattered continuum flux and an additional 'ultrasoft' X-ray excess component, or a warm absorber plus scattered continuum flux. There is evidence for variability at less than 1 keV energies that is unrelated to the 2-10 keV continuum. For an ionized-absorber description of NGC 4151, changes in the ionization state of the absorber appear to be unrelated to changes in the ionizing continuum.

Weaver, K. A.↗

NASA NTRS1995

Continuation of Studies of X-Ray Binaries with Ginga

The key goal of the observation of X0748-67B was to study changes in the time of the X-ray eclipses in order to determine the orbital period, which, in turn allows us to infer properties of the system. We attempted to carry out ROSAT observations but both scheduled pointings missed the requested ephemerides to see the eclipses. We were, however, able to use ASCA performance verification phase data to undertake our intended scientific goal and the combined ASCA/Ginga data were published as: "Is the changing orbital period of EXO 0748-676 evidence for a triple system?", and was observed by Ginga on two occasions. Mr. Thomas has conducted spectral and temporal extractions of these data. These data have been folded on the orbital period and the variation of low energy absorption and high energy iron line emission studied.

Nousek, John A.↗

NASA NTRS1997

ASCA Observation of the Dipping X-Ray Source X1916-053

We present the results of timing and spectral studies of the dipping X-ray source X1916-053, observed by ASCA during its Performance Verification phase. The detected dipping activity is consistent with previous observations, with a period of 3008s and an intermittent secondary dip observed roughly 0.4 out of phase with the primary dip. The energy spectra of different intensity states are fitted with a power law with partial covering fraction absorption and interstellar absorption. The increase in the hardness ratio during the primary and secondary dips, and the increase in the covering fraction and column density with decreasing X-ray intensity, all imply that the dipping is caused by the photo-absorbing materials which have been suggested to be where the accreted flow hits the outer edge of the disk materials. The spectra at all intensity levels show no apparent evidence for Fe or Ne emission lines. This may be due to the low metal abundance in the accretion flow. Alternatively, the X-ray luminosity of the central source may be too weak to excite emission lines, which are assumed to be produced by X-ray photoionization of the disk materials.

Ko, Yuan-Kuen↗

NASA NTRS1999

NASA Ames Research Center R and D Services Directorate Biomedical Systems Development

The Ames Research Center R&D Services Directorate teams with NASA, other government agencies and/or industry investigators for the development, design, fabrication, manufacturing and qualification testing of space-flight and ground-based experiment hardware for biomedical and general aerospace applications. In recent years, biomedical research hardware and software has been developed to support space-flight and ground-based experiment needs including the E 132 Biotelemetry system for the Research Animal Holding Facility (RAHF), E 100 Neurolab neuro-vestibular investigation systems, the Autogenic Feedback Systems, and the Standard Interface Glove Box (SIGB) experiment workstation module. Centrifuges, motion simulators, habitat design, environmental control systems, and other unique experiment modules and fixtures have also been developed. A discussion of engineered systems and capabilities will be provided to promote understanding of possibilities for future system designs in biomedical applications. In addition, an overview of existing engineered products will be shown. Examples of hardware and literature that demonstrate the organization's capabilities will be displayed. The Ames Research Center R&D Services Directorate is available to support the development of new hardware and software systems or adaptation of existing systems to meet the needs of academic, commercial/industrial, and government research requirements. The Ames R&D Services Directorate can provide specialized support for: System concept definition and feasibility Mathematical modeling and simulation of system performance Prototype hardware development Hardware and software design Data acquisition systems Graphical user interface development Motion control design Hardware fabrication and high-fidelity machining Composite materials development and application design Electronic/electrical system design and fabrication System performance verification testing and qualification.

Pollitt, J.↗

NASA NTRS2000

Technology Development for a Stirling Radioisotope Power System

NASA Glenn Research Center and the Department of Energy are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA Glenn is addressing key technology issues through the use of two NASA Phase II SBIRs with Stirling Technology Company (STC) of Kennewick, WA. Under the first SBIR, STC demonstrated a synchronous connection of two thermodynamically independent free-piston Stirling convertors and a 40 to 50 fold reduction in vibrations compared to an unbalanced convertor. The second SBIR is for the development of an Adaptive Vibration Reduction System (AVRS) that will essentially eliminate vibrations over the mission lifetime, even in the unlikely event of a failed convertor. This paper presents the status and results for these two SBIR projects and also discusses a new NASA Glenn in-house project to provide supporting technology for the overall Stirling radioisotope power system development. Tasks for this new effort include convertor performance verification, controls development, heater head structural life assessment, magnet characterization and thermal aging tests, FEA analysis for a lightweight alternator concept, and demonstration of convertor operation under launch and orbit transfer load conditions.

Thieme, Lanny G.↗

NASA NTRS2000

NASA GRC Technology Development Project for a Stirling Radioisotope Power System

NASA Glenn Research Center (GRC), the Department of Energy (DOE), and Stirling Technology Company (STC) are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA GRC is conducting an in-house project to provide convertor, component, and materials testing and evaluation in support of the overall power system development. A first characterization of the DOE/STC 55-We Stirling Technology Demonstration Convertor (TDC) under the expected launch random vibration environment was recently completed in the NASA GRC Structural Dynamics Laboratory. Two TDCs also completed an initial electromagnetic interference (EMI) characterization at NASA GRC while being tested in a synchronized, opposed configuration. Materials testing is underway to support a life assessment of the heater head, and magnet characterization and aging tests have been initiated. Test facilities are now being established for an independent convertor performance verification and technology development. A preliminary Failure Mode Effect Analysis (FMEA), initial finite element analysis (FEA) for the linear alternator, ionizing radiation survivability assessment, and radiator parametric study have also been completed. This paper will discuss the status, plans, and results to date for these efforts.

Thieme, Lanny G.↗

NASA NTRS2000

Update on the NASA GRC Stirling Technology Development Project

The Department of Energy, NASA Glenn Research Center (GRC), and Stirling Technology Company (STC) are developing a free-piston Stirling convertor for a Stirling radioisotope power system (SRPS) to provide spacecraft on-board electric power for NASA deep space missions. The SRPS has recently been identified for potential use on the Europa Orbiter and Solar Probe Space Science missions. Stirling is also now being considered for unmanned Mars rovers. NASA GRC is conducting an in-house project to assist in developing the Stirling convertor for readiness for space qualification and mission implementation. As part of this continuing effort, the Stirling convertor will be further characterized under launch environment random vibration testing, methods to reduce convertor electromagnetic interference (EMI) will be developed, and an independent performance verification will be completed. Convertor life assessment and permanent magnet aging characterization tasks are also underway. Substitute organic materials for the linear alternator and piston bearing coatings for use in a high radiation environment have been identified and have now been incorporated in Stirling convertors built by STC for GRC. Electromagnetic and thermal finite element analyses for the alternator are also being conducted. This paper discusses the recent results and status for this NASA GRC in-house project.

Thieme, Lanny G.↗

NASA NTRS2002

Primary Mirror Figure Maintenance of the Hobby-Eberly Telescope using the Segment Alignment Maintenance System

The Segment Alignment Maintenance System (SAMs) was installed on McDonald Observatory's Hobby-Eberly Telescope (HET) in August 2001. The SAMs became fully operational in October 2001. The SAMs uses a system of 480 inductive edge sensors to correct misalignments of the HET's 91 primary mirror segments when the segments are perturbed from their aligned reference positions. A special observer estimated and corrects for the global radius of curvature (GroC) mode, a mode unobservable by the edge sensors. The SAMs edge sensor system and (GroC) estimator are able to maintain HET's primary figure for much longer durations than previously had been observed. Telescope image quality has improved, and the amount of overhead time required from primary mirror alignment has been reduced. This paper gives a functional description of the SAMs control system and presents performance verification data. This paper also describes how the SAMs has improved the operational efficiency of the HET.

Rakoczy, John↗

NASA NTRS2002

Global Radius of Curvature Estimation and Control for the Hobby-Eberly Telescope

A system, which estimates the global radius of curvature (GroC) and corrects for changes in GroC on a segmented primary mirror has been developed for and verified on McDonald Observatory's Hobby Eberly Telescope (HET). The GroC estimation and control system utilizes HET's primary mirror control (PMC) system and the Segment Alignment Maintenance System (SAMS), an inductive edge sensor system. A special set of boundary conditions is applied to the derivation of the optimal edge match control. The special boundary conditions allow the further derivation of an observer, which enables estimation and control of the Groc mode to within HET's specification. The magnitude of the GroC mode can then be controlled despite the inability of the SAMS edge sensor system, by itself, to observe or control the GroC mode. The observer can be extended to any segmented mirror telescope. It will be shown that the observer improves with accuracy as the number of segments increases. This paper presents the mathematical theory of the observer. Simulation results will demonstrate the inherent accuracy and robustness of the system. Performance verification data from the HET will be presented.

Rakoczy, John↗

NASA NTRS2000

First XMM-Newton Observations of a Cataclysmic Variable II: Spectral Studies of OY Car

We present XMM-Newton X-ray spectra of the disc accreting cataclysmic variable OY Car, which were obtained during the performance verification phase of the mission. These data were taken 4 days after a short outburst. In the EPIC spectra we find strong Iron K(beta) emission with weaker Iron K(alpha) emission together with Silicon and Sulphur lines. The spectra are best fitted with a three temperature plasma model with a partial covering absorber. Multiple temperature emission is confirmed by the emission lines seen in the RGS spectrum and the H/He like intensity ratio for Iron and Sulphur which imply temperatures of approx. 7keV and approx. 3keV respectively.

Ramsay, Gavin↗

NASA NTRS2000

Complex Resonance Absorption Structure in the X-Ray Spectrum of IRAS 13349+2438

The luminous infrared-loud quasar IRAS 13349+2438 was observed with the XMM - Newton Observatory as part of the Performance Verification program. The spectrum obtained by the Reflection Grating Spectrometer (RGS) exhibits broad (FWHM - 1400 km/s) absorption lines from highly ionized elements including hydrogen- and helium-like carbon, nitrogen, oxygen, and neon, and several iron L - shell ions (Fe XVII - XX). Also shown in the spectrum is the first astrophysical detection of a broad absorption feature around lambda = 16 - 17 A identified as an unresolved transition array (UTA) of 2p - 3d inner-shell absorption by iron M-shell ions in a much cooler medium; a feature that might be misidentified as an O VII edge when observed with moderate resolution spectrometers. No absorption edges are clearly detected in the spectrum. We demonstrate that the RGS spectrum of IRAS 13349+2438 exhibits absorption lines from two distinct regions, one of which is tentatively associated with the medium that produces the optical/UV reddening.

Sako, M.↗

NASA NTRS2004

Restoring Redundancy to the Wilkinson Microwave Anisotrophy Probe Propulsion System

The Wilkinson Microwave Anisotropy Probe is a follow-on to the Differential Microwave Radiometer instrument on the Cosmic Background Explorer. Attitude control system engineers discovered sixteen months before launch that configuration changes after the critical design review had resulted in a significant migration of the spacecraft's center of mass. As a result, the spacecraft no longer had a viable backup control mode in the event of a failure of the negative pitch-axis thruster. A tiger team was formed and identified potential solutions to this problem, such as adding thruster-plume shields to redirect thruster torque, adding or removing mass from the spacecraft, adding an additional thruster, moving thrusters, bending thruster nozzles or propellant tubing, or accepting the loss of redundancy. The project considered the impacts on mass, cost, fuel budget, and schedule for each solution, and decided to bend the propellant tubing of the two roll-control thrusters to allow the pair to be used for backup control in the negative pitch axis. This paper discusses the problem and the potential solutions, and documents the hardware and software changes and verification performed. Flight data are presented to show the on-orbit performance of the propulsion system and lessons learned are described.

O'Donnell, James R., Jr.↗