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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.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Probing for Pulsars: An XMM Study of the Composite SNRS G327.1-1.1 and CTA1

The subject grant is for analysis of XMM data from the supernova remnant CTA1. Our investigation centered on the study of the compact source Rx 50007.0+7302 that, based on our previous observations, appears to be a neutron star powering a wind nebula in the remnant interior. This compact source has also been suggested as the counterpart of the EGRET source 2EG J0008+7307. The analysis of the data from the compact source is complete. We find that the spectrum of the source is well described by a power law with the addition of a soft thermal component that may correspond to emission from hot polar cap regions or to cooling emission from a light element atmosphere over the entire star. There is evidence of extended emission on small spatial scales which may correspond to structure in the underlying synchrotron nebula. Extrapolation of the nonthermal emission component to gamma-ray energies yields a flux that is consistent with that of 2EG J0008+7307, thus strengthening the proposition that there is a gamma-ray emitting pulsar at the center of CTA 1. Our timing studies with the EPIC pn data revealed no evidence for pulsations, however; we set an upper limit of 61% on the pulsed fraction from this source. The results from this study were presented in a poster at the recent IAU Symposium in Sydney, Australia. A paper summarizing these results, entitled "Xray Observations of the Compact Source in CTA 1" (Slane et al.) has been submitted for publication in the Astrophysical Journal.

Slane, Patrick↗
NASA NTRS2004

Probing for Pulsars in XMM Study of the Composite SNRS G327.1-1.1 and CTA 1

The subject grant is for analysis of XMM data from the supernova remnant CTA1. Our investigation centered on the study of the compact source RX 50007.0+7302 that, based on our previous observations, appears to be a neutron star powering a wind nebula in the remnant interior. This compact source has also been suggested as the counterpart of the EGRET source 2EG J0008+7307. The analysis of the data from the compact source is complete. We find that the spectrum of the source is well described by a power law with the addition of a soft thermal component that may correspond to emission from hot polar cap regions or to cooling emission from a light element atmosphere over the entire star. There is evidence of extended emission on small spatial scales which may correspond to structure in the underlying synchrotron nebula. Extrapolation of the nonthermal emission component to gamma-ray energies yields a flux that is consistent with that of 2EG J0008+7307, thus strengthening the proposition that there is a gamma-ray emitting pulsar at the center of CTA 1. Our timing studies with the EPIC pn data revealed no evidence for pulsations, however; we set an upper limit of 61% on the pulsed fraction from this source. The results from this study were presented.

Mushotsky, Richard↗
NASA NTRS1993

Reliability study of the NiH2 strain gage

This paper summarizes a joint study by Gates Aerospace Batteries (GAB) and the Reliability Analysis Center (RAC). This study characterizes the reliability and robustness of the temperature compensated strain gages currently specified for sensing of internal pressure of NiH2 cells. These strain gages are characterized as fully encapsulated, metallic foil grids with known resistance that varies with deformation. The measurable deformation, when typically installed on the hemispherical portion of a NiH2 cell, is proportional to the material stresses as generated by internal cell pressures. The internal pressure sensed in this manner is calibrated to indicate the state-of-charge for the cell. This study analyzes and assesses both robustness and reliability for the basic design of the strain gage, the installation of the strain gage, and the circuitry involved.

Klein, Glenn C.↗
NASA NTRS1999

Power to Explore: A History of the Marshall Space Flight Center, 1960-1990

This scholarly study of NASA's Marshall Space Flight Center places the institution in social, political, scientific and technological context. It traces the evolution of Marshall, located in Huntsville, Alabama, from its origins as an Army missile development organization to its status in 1990 as one of the most diversified of NASA's field Center. Chapters discuss military rocketry programs in Germany and the United States, Apollo-Saturn, Skylab, Space shuttle, Spacelab, the Space Station, and various scientific and technical projects including the Hubble Space Telescope. It sheds light not only on the history of space technology, science and exploration, but also on the Cold War, federal politics and complex organizations.

Dunar, Andrew J.↗
NASA NTRS1994

Flow quality studies of the NASA Lewis Research Center Icing Research Tunnel diffuser

The purpose was to document the airflow characteristics in the diffuser of the NASA Lewis Research Center Icing Research Tunnel and to determine the effects of vortex generators on the flow quality in the diffuser. The results were used to determine how to improve the flow in this portion of the tunnel so that it can be more effectively used as an icing test section and such that overall tunnel efficiency can be improved. The demand for tunnel test time and the desire to test models that are too large for the test section were two of the drivers behind this diffuser study. For all vortex generator configurations tested, the flow quality was improved.

Arrington, E. Allen↗
NASA NTRS1984

The QUASAT mission: An overview

The QUASAT VLBI mission to provide images of the total intensity and polarized emission of compact radio sources in continuum and line with a combination of angular resolution and quality unattainable from Earth is summarized. The astrophysical goals encompass the study of active nuclei at scales appropriate to the outer reaches of accretion disks and the optical broad and narrow line regions; the study of galactic continuum sources in stars and in the galactic center; and spectroscopic studies of galactic and extragalactic molecular masers to determine their role in the life cycle of stars, and their use as direct distance indicators.

Schilizzi, R. T.↗
NASA NTRS2000

Flow Quality Studies of the NASA Glenn Research Center Icing Research Tunnel Circuit (1995 Tests)

The purpose of conducting the flow-field surveys described in this report was to more fully document the flow quality in several areas of the tunnel circuit in the NASA Glenn Research Center Icing Research Tunnel. The results from these surveys provide insight into areas of the tunnel that were known to exhibit poor flow quality characteristics and provide data that will be useful to the design of flow quality improvements and a new heat exchanger for the facility. An instrumented traversing mechanism was used to survey the flow field at several large cross sections of the tunnel loop over the entire speed range of the facility. Flow-field data were collected at five stations in the tunnel loop, including downstream of the fan drive motor housing, upstream and downstream of the heat exchanger, and upstream and downstream of the spraybars located in the settling chamber upstream of the test section. The data collected during these surveys greatly expanded the data base describing the flow quality in each of these areas. The new data matched closely the flow quality trends recorded from earlier tests. Data collected downstream of the heat exchanger and in the settling chamber showed how the configuration of the folded heat exchanger affected the pressure, velocity, and flow angle distributions in these areas. Smoke flow visualization was also used to qualitatively study the flow field in an area downstream of the drive fan and in the settling chamber/contraction section.

Arrington, E. Allen↗
NASA NTRS2023

The Impact (Influence) of Stakeholder Participation in the Logic Modeling Process: A Case Study from NASA Goddard Space Flight Center

This is a three-paper dissertation that responds to a call for empirical research on stakeholder influence in the implementation of evaluation recommendations. The literature is consistent but mostly theoretical: stakeholder participation should positively influence and increase the probability of implementation (see e.g., Christie, 2011; Cousins and Earl, 1992); Fetterman, 2004). In response, I use two Goddard Space Flight Center engineering technical training and development programs to build a causal pathway argument supporting my proposition that stakeholder influence in the logic modeling process impacts organizational decision-making and change. I first introduce the logic modeling process as a tool to involve stakeholders in program and evaluation design (paper 1), then use the data collection process to implement the collaboratively constructed logic model outcomes (paper 2), and finally, I triangulate the data using the Toal (2009) Evaluation Involvement Scale (paper 3). I do this to “increase the validity of the findings” (Noble & Heale, 2019, p. 67) and to garner potential mechanisms. I found that stakeholder participation in the logic modeling process positively influenced the use of data to inform recommendations which in turn positively influenced implementation of evaluation recommendations. I identified the process itself as the mechanism and the key decision points as links or influencers. Potential factors included power and interest (measured by role) and time-on-job.

Organizational Decision-Making↗
NASA NTRS1982

A study of flight control requirements for advanced, winged, earth-to-orbit vehicles with far-aft center-of-gravity locations

Control requirements of Controlled Configured Design Approach vehicles with far-aft center of gravity locations are studied. The baseline system investigated is a fully reusable vertical takeoff/horizontal landing single stage-to-orbit vehicle with mission requirements similar to that of the space shuttle vehicle. Evaluations were made to determine dynamic stability boundaries, time responses, trim control, operational center-of-gravity limits, and flight control subsystem design requirements. Study tasks included a baseline vehicle analysis, an aft center of gravity study, a payload size study, and a technology assessment.

Hepler, A. K.↗
NASA NTRS1976

A study of the remote neighborhood office center concept

The substitution of communications for commuting to work is examined from several aspects. Attention is focused on the possibility of certain groups of white collar workers conducting their business affairs through a network of Remote Neighborhood Office Centers (RNOC's) located near their homes. Typically, employees would communicate with their headquarters organizations by means of voice and digital circuits. Although current technology is readily able to support such an RNOC network, the main problems confronting would-be implementers center around the need for demonstrating that a sufficient number of business operations can be carried out in such a decentralized configuration as efficiently as they are under more conventional circumstances. The description of a pilot program is presented which is intended to identify pacing issues that must be settled before firm conclusions can be reached on whether the concept is operationally viable.

Source record↗
NASA NTRS1978

Payload operations control center network (POCCNET) systems definition phase study report

The results of the studies performed during the systems definition phase of POCCNET are presented. The concept of POCCNET as a system of standard POCCs is described and an analysis of system requirements is also included. Alternative systems concepts were evaluated as well as various methods for development of reliable reusable software. A number of POCC application areas, such as command management, on board computer support, and simulation were also studied. Other areas of investigation included the operation of POCCNET systems, the facility requirements and usage.

Desjardins, R.↗
NASA NTRS1979

The NASA-Ames Research Center stratospheric aerosol model. 2. Sensitivity studies and comparison with observatories

Sensitivity tests were performed on a one-dimensional, physical-chemical model of the unperturbed stratospheric aerosols, and model calculations were compared with observations. The tests and comparisons suggest that coagulation controls the particle number mixing ratio, although the number of condensation nuclei at the tropopause and the diffusion coefficient at high altitudes are also important. The sulfur gas source strength and the aerosol residence time are much more important than the supply of condensation nuclei in establishing mass and large particle concentrations. The particle size is also controlled mainly by gas supply and residence time. In situ observations of the aerosols and laboratory measurements of aerosols, parameters that can provide further information about the physics and chemistry of the stratosphere and the aerosols found there are provided.

Toon, O. B.↗
NASA NTRS1979

Feasibility study of an integrated optic switching center

The design of a high data rate switching center for a satellite tracking station is discussed. The feasibility of a switching network using an integrated switching matrix is assessed. The preferred integrated optical switching scheme was found to be an electro-optic Bragg diffraction switch. To ascertain the advantages of the integrated optics switching center, its properties are compared to those of opto-electronic and to electronics switching networks.

Source record↗
NASA NTRS1985

Space station data system analysis/architecture study. Task 3: Trade studies, DR-5, volume 2

Results of a Space Station Data System Analysis/Architecture Study for the Goddard Space Flight Center are presented. This study, which emphasized a system engineering design for a complete, end-to-end data system, was divided into six tasks: (1); Functional requirements definition; (2) Options development; (3) Trade studies; (4) System definitions; (5) Program plan; and (6) Study maintenance. The Task inter-relationship and documentation flow are described. Information in volume 2 is devoted to Task 3: trade Studies. Trade Studies have been carried out in the following areas: (1) software development test and integration capability; (2) fault tolerant computing; (3) space qualified computers; (4) distributed data base management system; (5) system integration test and verification; (6) crew workstations; (7) mass storage; (8) command and resource management; and (9) space communications. Results are presented for each task.

Source record↗
NASA NTRS1990

An overview of selected NASP aeroelastic studies at the NASA Langley Research Center

Following an initial discussion of the NASP flight environment, the results of recent aeroelastic testing of NASP-type highly swept delta-wing models in Langley's Transonic Dynamics Tunnel (TDT) are summarized. Subsonic and transonic flutter characteristics of a variety of these models are described, and several analytical codes used to predict flutter of these models are evaluated. These codes generally provide good, but conservative predictions of subsonic and transonic flutter. Also, test results are presented on a nonlinear transonic phenomena known as aileron buzz which occurred in the wind tunnel on highly swept delta wings with full-span ailerons. An analytical procedure which assesses the effects of hypersonic heating on aeroelastic instabilities (aerothermoelasticity) is also described. This procedure accurately predicted flutter of a heated aluminum wing on which experimental data exists. Results are presented on the application of this method to calculate the flutter characteristics of a fine-element model of a generic NASP configuration. Finally, it is demonstrated analytically that active controls can be employed to improve the aeroelastic stability and ride quality of a generic NASP vehicle flying at hypersonic speeds.

Spain, Charles V.↗
NASA NTRS1997

A Study of Supernova Remnants with Center-Filled X-Ray Morphology

CTA 1 is a center-filled supernova remnant (SNR) whose morphology and spectrum indicate the presence of a central pulsar, a synchrotron nebula, and a thermal component associated with the expansion of the blast wave into the interstellar medium. The centrally bright emission surrounds the position of a faint point source of x-rays observed with the ROSAT PSPC. Here we report on ASCA observations that confirm the nonthermal nature of the diffuse emission from the central regions of the remnant. We also present evidence for weak thermal emission that appears to increase in strength toward the outer boundary of the SNR. Thus, CTA 1 appears to be an x-ray composite remnant. Both the aftermath of the explosive supernova event and the energetic compact core are observable.

Slane, Patrick O.↗