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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 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Egypt in the framework of global tectonics

An overview is presented to explicitly describe the role of global tectonics in the tectonic and geologic history of Egypt. The major global tectonic events that have directly or indirectly affected the geology of Egypt are summarized and those events are described chronologically, emphasizing the regional geological implications of each event. It is shown that the analysis of Egyptian geological history within the framework of global tectonics suggests that most of the major geological features of Egypt can be explained in terms of the interaction of global tectonics. Finally, it appears that Egypt is entering a new phase of the Wilson cycle of opening and closing of oceans.

Morgan, Paul↗
NASA NTRS1991

Concept of nondestructive evaluation

The history of nondestructive evaluation, a recently evolved basic testing philosophy, and some application of NDE are examined with emphasis on aerospace applications. The discussion covers the definition of NDE, chronological development, NDE methods and systems, the use of NDE for process control, NDE for ceramics and composites, NDE for fracture control in glass, and science aspects of NDE. Specific examples of NDE applications are given.

Chern, E. J.↗
NASA NTRS1991

NASA cryogenic fluid management space experiment efforts

A history of technological development for subcritical cryogenic fluid management (CFM) through space experiments is given for the period 1960 to 1990. Space experiments with liquid hydrogen were conducted in the early 1960s. Efforts since then have consisted of studies and designs of potential space experiments. A chronology of CFM space experiments and design efforts is included.

Glover, Daniel↗
NASA NTRS1991

Impact craters on Venus

Compared with volcanism and tectonism, impact cratering on Venus has played an overall minor role in sculpting the present-day landscape. The study of Venus impact craters is vital to help place the chronology of the geologic features on the surface in the context of the planet's geological evolution. The degradation of impact craters also provides information on surface and interior processes, particularly alteration by tectonism and volcanism. Through orbit 1422, Magellan mapped about 450 impact craters, with diameters ranging from 2 to 275 km, within an area of about 226 million sq km, or 49 percent of the planet's surface. These craters and their associated deposits show surprisingly little evidence of degradation at the 75 m/pixel resolution of the Magellan SAR. Remarkably few craters in the Magellan images appear to be in the process of being buried by volcanic deposits or destroyed by tectonic activity.

Schaber, G. G.↗
NASA NTRS1991

Resource representation in COMPASS

A set of viewgraphs on resource representation in COMPASS is given. COMPASS is an incremental, interactive, non-chronological scheduler written in Ada with an X-windows user interface. Beginning with an empty schedule, activities are added to the schedule one at a time, taking into consideration the placement of the activities already on the timeline and the resources that have been reserved for them. The order that the activities are added to the timeline and their location on the timeline are controlled by selection and placement commands invoked by the user. The order that activities are added to the timeline and their location are independent. The COMPASS code library is a cost effective platform for the development of new scheduling applications. It can be effectively used off the shelf for compatible scheduling applications or it can be used as a parts library for the development of custom scheduling systems.

Fox, Barry R.↗
NASA NTRS1991

Cs-135 - Ba-135: A new cosmochronometric constraint on the origin of the Earth and the astrophysical site of the origin of the solar system

It is argued that if Cs-135 was indeed present in the early solar system at the level inferred from evidence presented here, then two major conclusions follow. (1) A supernova contributed newly synthesized r-process matter into the protosolar reservoir within approx. 5 Ma of the Cs/Ba fractionation recorded in LEW 86010; (2) The strong Cs depletion in the bulk Earth reservoir (Cs-133/Ba-135 approx. 0.1) took place very early in solar system history. If this volatile loss was pre-accretionary, then the accretionary chronology of the Earth is not constrained. However, if it is a consequence of accretion, then the very tight time constraint of approx. less than 5 Ma (rel. to LEW 86010) is obtained for accretion of most of the Earth's mass.

Harper, C. L.↗
NASA NTRS1991

A decade on board America's Space Shuttle

Spectacular moments from a decade (1981-1991) of Space Shuttle missions, captured on film by the astronauts who flew the missions, are presented. First hand accounts of astronauts' experiences aboard the Shuttle are given. A Space Shuttle mission chronology featuring flight number, vehicle name, crew, launch and landing dates, and mission highlights is given in tabular form.

Source record↗
NASA NTRS1991

Operations mission planner beyond the baseline

The scheduling of Space Station Freedom must satisfy four major requirements. It must ensure efficient housekeeping operations, maximize the collection of science, respond to changes in tasking and available resources, and accommodate the above changes in a manner that minimizes disruption of the ongoing operations of the station. While meeting these requirements the scheduler must cope with the complexity, scope, and flexibility of SSF operations. This requires the scheduler to deal with an astronomical number of possible schedules. The Operations Mission Planner (OMP) is centered around minimally disruptive replanning and the use of heuristics limit search in scheduling. OMP has already shown several artificial intelligence based scheduling techniques such as Interleaved Iterative Refinement and Bottleneck Identification using Process Chronologies.

Biefeld, Eric↗
NASA NTRS1990

Sixty-nine months in space: A history of the first LDEF (Long Duration Exposure Facility)

The LDEF project is summarized from its conception, through its deployment, to the return of the experiments. A LDEF chronology and a fact sheet is included. The experiments carried more than 10,000 specimens to gather scientific data and to test the effects of long term space exposure on spacecraft materials, components, and systems. Results will be invaluable for the design of future spacecraft such as Space Station Freedom.

Source record↗
NASA NTRS1992

Variable-camber systems integration and operational performance of the AFTI/F-111 mission adaptive wing

The advanced fighter technology integration, the AFTI/F-111 aircraft, is a preproduction F-111A testbed research airplane that was fitted with a smooth variable-camber mission adaptive wing. The camber was positioned and controlled by flexing the upper skins through rotary actuators and linkages driven by power drive units. The wing camber and control system are described. The measured servoactuator frequency responses are presented along with analytical predictions derived from the integrated characteristics of the control elements. A mission adaptive wing system chronology is used to illustrate and assess the reliability and dependability of the servoactuator system during 1524 hours of ground tests and 145 hours of flight testing.

Smith, John W.↗
NASA NTRS1992

The NASA Langley laminar-flow-control experiment on a swept, supercritical airfoil: Evaluation of initial perforated configuration

The initial evaluation of a large-chord, swept, supercritical airfoil incorporating an active laminar-flow-control (LFC) suction system with a perforated upper surface is documented in a chronological manner, and the deficiencies in the suction capability of the perforated panels as designed are described. The experiment was conducted in the Langley 8-Foot Transonic Pressure Tunnel. Also included is an evaluation of the influence of the proximity of the tunnel liner to the upper surface of the airfoil pressure distribution.

Harris, Charles D.↗
NASA NTRS1991

Airborne SAR determination of relative ages of Walker Valley moraines, eastern Sierra Nevada

A regional study of the distribution and elevations of Pleistocene moraines in the Andes requires a method of determining relative age from space. One of our primary objectives is to establish the relative chronology of major climatic events responsible for glaciation in the Andes and other regions that are difficult to access on the ground and where suitable material for absolute age determination is lacking. The sensitivity of radar to surface roughness makes it possible to develop a remotely-based relative dating technique for landforms for which surface age and roughness can be correlated. We are developing such a technique with Airborne Synthetic Aperture Radar (AIRSAR) imagery of the eastern Sierra Nevada where independent evidence is available for the ages and physical characteristics of moraines. The Sierra Nevada moraines are similar in form and environmental setting to Andean moraines that we have targeted for study during the pending Shuttle Imaging Radar-C (SIR-C) mission. SAR imagery is used to differentiate the ages of five moraine sequences of Walker Valley in the eastern Sierra Nevada. Other aspects of this investigation are briefly discussed.

Fox, A.↗
NASA NTRS1992

ETO cloud studies for FIRE 2, part 1

This research program in support of Project FIRE (First ISCCP Regional Experiment) involved two efforts. The results of the first effort, which were in direct support of the Extended Time Observations (ETO) component, are described here. Over the period from June 1990 through May 1991, our remote sensing systems were applied to providing ground-truth cirrus cloud observations for a total of 71 NOAA polar orbiting satellite overpasses. (Chronological tables of this effort are provided.) The primary remote sensor was a dual-polarization ruby (0.694 microns wavelength) lidar, although mid-way through the program we added a number of radiometers to assess the surface radiation budget and cirrus cloud infrared emittance, and some supplemental observations from a Ka-band (8.6 mm) radar were also collected. These studies were conducted from the Facility for Atmospheric Remote Sensing (FARS) at 40 degrees 46 minutes 00 seconds north latitude and 111 degrees 49 minutes 38 seconds east longitude. We also investigated the unusual characteristics of a subset of ETO case studies involving cirrus that generated solar and lunar corona displays. As we reported recently (reprint attached), these cirrus were atypically high and cold in relation to our total midlatitude cloud sample, and were comprised of unexpectedly small ice crystals from 10 to 30 microns in dimension. This finding lends some credence to the so-called cirrus small particle radiative anomaly, but only for very cold (less than -60 C) cirrus clouds. In a supplement, we will describe the design and testing of a prototype cirrus cloud polar nephelometer, which we constructed as part of our second research effort, to allow scattering phase functions to be obtained in future in situ cirrus research.

Sassen, Kenneth↗
NASA NTRS1992

Meteoritics and the origins of atomic nuclei

A review of new issues that have emerged in the study of nucleosynthesis is presented. The issues explored in detail are: (1) a quantitative s-process theory, (2) cosmoradiogenic chronology, (3) explosive nucleosynthesis and gamma-ray astronomy, and (4) cosmic chemical memory. The unexpected abundance patterns within meteorites that were suggested by the resolution of these issues are described.

Clayton, Donald D.↗
NASA NTRS1992

Martian parent craters for the SNC meteorites

Information on the petrology and ages of the SNC meteorites, together with geological data derived from Viking Orbiter images, are used to identify 25 candidate impact craters in the Tharsis region of Mars that could possibly be the source craters for these meteorites. The craters chosen as candidate source craters had diameters greater than 10 km, morphologies indicative of young craters, and satisfied both the petrological criteria of the SNCs and the proposed 1.3 Ga crystallization ages. On the basis of the constraints implied by the identification of the candidate source craters, interpretations of the absolute chronology of Mars are proposed.

Mouginis-Mark, P. J.↗
NASA NTRS1991

The CRAF/Cassini power subsystem - Preliminary design update

A chronology is provided of the rationale leading from the early Mariner spacecraft to the CRAF/Cassini Mariner Mark II power subsystem architecture. The display pathway began with a hybrid including a solar photovoltaic array, a radioisotope thermoelectric generator (RTG), and a battery supplying a power profile with a peak loading of about 300 W. The initial concept was to distribute power through a new solid-state, programmable switch controlled by an embedded microprocessor. As the overall mission, science, and project design matured, the power requirements increased. The design evolved from the hybrid to two RTG plus batteries to meet peak loadings of near 500 W in 1989. Later that year, circumstances led to abandonment of the distributed computer concept and a return to centralized control. Finally, as power requirements continued to grow, a third RTG was added to the design and the battery removed, with the return to the discharge-controller for transients during fault recovery procedures.

Atkins, Kenneth L.↗
NASA NTRS1993

Software For Graphical Representation Of A Network

System Visualization Tool (SVT) computer program developed to provide systems engineers with means of graphically representing networks. Generates diagrams illustrating structures and states of networks defined by users. Provides systems engineers powerful tool simplifing analysis of requirements and testing and maintenance of complex software-controlled systems. Employs visual models supporting analysis of chronological sequences of requirements, simulation data, and related software functions. Applied to pneumatic, hydraulic, and propellant-distribution networks. Used to define and view arbitrary configurations of such major hardware components of system as propellant tanks, valves, propellant lines, and engines. Also graphically displays status of each component. Advantage of SVT: utilizes visual cues to represent configuration of each component within network. Written in Turbo Pascal(R), version 5.0.

Mcallister, R. William↗