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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 325 records · Page 18

Large eddy simulation - The next five years

The prospect of major improvements in the performance of computers in the next five years means that large eddy simulation (LES), which has until now been strictly a research tool, may become a top-of-the-line engineering tool. In this paper, the historical development and past contributions of LES are reviewed. Then a discussion of the potential for applications of LES in new areas and of the developments needed to make LES a tool for the practicing engineer is given.

Ferziger, J. H.↗

Optical-system design for next-generation pushbroom sensors

Next-generation pushbroom sensors for earth observation require high-performance optics that provide high spatial resolution over wide fields of view. Specifically, blur diameters on the order of 10 to 15 microns are needed over 5 to 15 deg fields. In addition to this fundamental level of optical performance, other characteristics, such as spatial coregistration of spectral bands, flat focal plane, telecentricity, and workable pupil location are significant instrument design considerations. The detector-assembly design, optical line-of-sight pointing method and sensor packaging all hinge on these secondary attributes. Moreover, the need for broad spectral coverage, ranging from 0.4 to 12.5 microns, places an additional constraint on optical design. This paper presents alternative design forms that are candidates for wide-field pushbroom sensors, and discusses the instrument-design tradeoffs that are linked to the selection of these alternate optical approaches.

Mika, A. M.↗

Shuttle II - The next generation

A comparative evaluation is conducted for next-generation Space Shuttle-type system configurations, in light of mission and design goals, performance and operational requirements, and technology development needs and opportunities. Cargo vehicle options presently entertained are an unmanned Shuttle Derivative Vehicle and a Heavy Lift Launch Vehicle. Two high priority manned vehicle options are small (35,000-lb payload) and large (150,000-lb payload) fully reusable vehicles. Attention is given to single stage vs. two-stage 'Shuttle II' system performance and economic projections.

Eldred, C. H.↗

Global interconnectivity in the next two decades - A scenario

The present paper provides a description of a part of NASA's current long range plans, taking into account the development of hierarchal space switching centers and laser intersatellite links which can interconnect the globe. It is pointed out that a special objective involves the development of technology and satellite architecture for reducing the cost of an end-to-end voice message per minute from the present average value of around $.40 now realized by terrestrial telephone systems to less than $.10. The next decade of NASA communications activity (1985-1995) is discussed, giving attention to the Advanced Communications Technology Satellite ACTS (July 1984) which will test the technology of space switchboard and signal processing in space. The environment of the decade 1985-1995 is considered along with the roles of communications satellites, the hierarchies of terrestrial public switched networks, cost comparisons of terrestrial and space point-to-point links, and concomitant technology developments related to supercomputers.

Lovell, R.↗

Passive microwave radiometer experiment for GOES-NEXT

A new passive microwave radiometer (PMR) experiment for GOES-NEXT is described. The PMR, expected to be in orbit in the early 1990's, is a multichannel microwave radiometer which will allow new measurements of temperature and moisture structure and precipitation by penetrating much of the overlying cloud cover near significant weather systems. PMR experimental objectives are to use a geostationary platform for the first time to obtain passive microwave imagery and soundings in a high time frequency mode to address several scientific objectives. These scientific objectives address current problems of atmospheric science at the mesoscale and in climate research.

Vonder Haar, Thomas H.↗

Civil propulsion technology for the next twenty-five years

The next twenty-five years will see major advances in civil propulsion technology that will result in completely new aircraft systems for domestic, international, commuter and high-speed transports. These aircraft will include advanced aerodynamic, structural, and avionic technologies resulting in major new system capabilities and economic improvements. Propulsion technologies will include high-speed turboprops in the near term, very high bypass ratio turbofans, high efficiency small engines and advanced cycles utilizing high temperature materials for high-speed propulsion. Key fundamental enabling technologies include increased temperature capability and advanced design methods. Increased temperature capability will be based on improved composite materials such as metal matrix, intermetallics, ceramics, and carbon/carbon as well as advanced heat transfer techniques. Advanced design methods will make use of advances in internal computational fluid mechanics, reacting flow computation, computational structural mechanics and computational chemistry. The combination of advanced enabling technologies, new propulsion concepts and advanced control approaches will provide major improvements in civil aircraft.

Rosen, Robert↗

On the next generation of reliability analysis tools

The current generation of reliability analysis tools concentrates on improving the efficiency of the description and solution of the fault-handling processes and providing a solution algorithm for the full system model. The tools have improved user efficiency in these areas to the extent that the problem of constructing the fault-occurrence model is now the major analysis bottleneck. For the next generation of reliability tools, it is proposed that techniques be developed to improve the efficiency of the fault-occurrence model generation and input. Further, the goal is to provide an environment permitting a user to provide a top-down design description of the system from which a Markov reliability model is automatically constructed. Thus, the user is relieved of the tedious and error-prone process of model construction, permitting an efficient exploration of the design space, and an independent validation of the system's operation is obtained. An additional benefit of automating the model construction process is the opportunity to reduce the specialized knowledge required. Hence, the user need only be an expert in the system he is analyzing; the expertise in reliability analysis techniques is supplied.

Babcock, Philip S., IV↗

Max '91: Flare research at the next solar maximum

To address the central scientific questions surrounding solar flares, coordinated observations of electromagnetic radiation and energetic particles must be made from spacecraft, balloons, rockets, and ground-based observatories. A program to enhance capabilities in these areas in preparation for the next solar maximum in 1991 is recommended. The major scientific issues are described, and required observations and coordination of observations and analyses are detailed. A program plan and conceptual budgets are provided.

Dennis, Brian↗

Space launch systems - Current United States plans and the next logical steps through 2000

The United States space transportation plans are discussed with emphasis on returning the Titan and the Shuttle to operational status. In particular, Shuttle enhancements via advanced solid rocket boosters and replacement of solid rocket boosters by liquid rocket boosters are examined. The Shuttle-C vehicle is then discussed as the next logical step that could provide a heavy launch capability in the early 1990s. The Shuttle-C will provide assured and flexible access to space for large Centaur-class payloads, for Space Station assembly, and for planetary missions.

Branscome, Darrell R.↗

Astrophysics space observatories - The next 25 years

The design characteristics and performance capabilities of orbiting astrophysical observatory optics are projected from the state-of-the-art to the next 25 years. Attention is given to the possible features of large optical/UV observatories as well as to an advanced gamma-ray observatory that could employ the Space Shuttle's External Tank as its structural basis. It is noted that telescope performance has reached fundamental technological barriers to further progress which demand radical innovations in optical configurations' design.

Morgan, S. H.↗

The U.S. Max '91 program of flare research at the next solar maximum

A brief summary is presented of Max '91, a proposed program to study the problems of flare physics during the next solar maximum. The program uses instruments on spacecraft, rockets, balloons, and ground-based observations to study the processes of particle acceleration and energy storage, release, and transport in solar flares. The space missions, instruments, and experiments included in the program are outlined.

Dennis, Brian R.↗

Nuclear thermal rockets - Next step to space

The prospects for the use of nuclear thermal rockets in manned interplanetary exploration are examined. These rockets offer the possibility for trip times on the order of a year or less in the next two decades. Mission prospects for gas-core concepts are emphasized, showing how such concepts meet the mission requirements.

Borowski, Stanley K.↗

PLAN-IT-2: The next generation planning and scheduling tool

PLAN-IT is a scheduling program which has been demonstrated and evaluated in a variety of scheduling domains. The capability enhancements being made for the next generation of PLAN-IT, called PLAN-IT-2 is discussed. PLAN-IT-2 represents a complete rewrite of the original PLAN-IT incorporating major changes as suggested by the application experiences with the original PLAN-IT. A few of the enhancements described are additional types of constraints, such as states and resettable-depletables (batteries), dependencies between constraints, multiple levels of activity planning during the scheduling process, pattern constraint searching for opportunities as opposed to just minimizing the amount of conflicts, additional customization construction features for display and handling of diverse multiple time systems, and reduction in both the size and the complexity for creating the knowledge-base to address the different problem domains.

Eggemeyer, William C.↗

The Deep Space Network: The challenges of the next 20 years - The 21st century

The Deep Space Network (DSN) has been the radio navigation and communications link between NASA's lunar and deep space missions for 30 years. In this paper, new mission opportunities over the next 20 years are discussed. The system design drivers and the DSN architectural concepts for those challenges are briefly considered.

Dumas, L. N.↗

Next manned transportation system

Avionics is the connecting link that integrates the hardware and software which satisfy systems requirements. Issues of the next manned transportation system are outlined: STS evolution; personnel launch system (PLS) sizing issues and constraints; PLS thermal protection system; PLS launch vehicle concepts; reliability and safety; advanced launch systems (ALS); near-term issues; avionics requirements; guideline to reduce operational costs; and critical human factors design considerations.

Erwin, Harry↗

The next generation

The next generation of computer systems are studied by examining the processes and methodologies. The present generation is ok for small projects, but not so good for large projects. They are not good for addressing the iterative nature of requirements, resolution, and implementation. They do not address complexity issues of requirements stabilization. They do not explicitly address reuse opportunities, and they do not help with people shortages. Therefore, there is a need to define and automate improved software engineering processes. Some help may be gained by reuse and prototyping, which are two sides of the same coin. Reuse library parts are used to generate good approximations to desired solutions, i.e., prototypes. And rapid prototype composition implies use of preexistent parts, i.e., reusable parts.

Yudkin, Howard↗

Next-generation in-situ science concepts and technology

This paper discusses the concepts of a next-generation in situ science program, named Sample Acquisition, Analysis, and Preservation (SAAP), established by NASA to develop critical technologies for remote identification, acquisition, processing, analysis, and preservation of materials for the in situ science, engineering characterization, and earth return. Special attention is given to the SAAP architecture, system design, remote sensing system, sample acquisition system, and methods for sample analysis. A diagram of the SAAP preliminary system conceptual design is included.

Muirhead, Brian↗

Satellite communications for the next generation telecommunication services and networks

Satellite communications can play an important role in provisioning the next-generation telecommunication services and networks, provided the protocols specifying these services and networks are satellite-compatible and the satellite subnetworks, consisting of earth stations interconnected by the processor and the switch on board the satellite, interwork effectively with the terrestrial networks. The specific parameters and procedures of frame relay and broadband integrated services digital network (B-ISDN) protocols which are impacted by a satellite delay. Congestion and resource management functions for frame relay and B-ISDN are discussed in detail, describing the division of these functions between earth stations and on board the satellite. Specific onboard and ground functions are identified as potential candidates for their implementation via neural network technology.

Chitre, D. M.↗