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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

All sources NASA NTRS DOE OSTI

NASA NTRS1991

The NASA Lewis Research Center Internal Fluid Mechanics Facility

An experimental facility specifically designed to investigate internal fluid duct flows is described. It is built in a modular fashion so that a variety of internal flow test hardware can be installed in the facility with minimal facility reconfiguration. The facility and test hardware interfaces are discussed along with design constraints of future test hardware. The plenum flow conditioning approach is also detailed. Available instrumentation and data acquisition capabilities are discussed. The incoming flow quality was documented over the current facility operating range. The incoming flow produces well behaved turbulent boundary layers with a uniform core. For the calibration duct used, the boundary layers approached 10 percent of the duct radius. Freestream turbulence levels at the various operating conditions varied from 0.64 to 0.69 percent of the average freestream velocity.

Porro, A. R.↗

NASA NTRS1990

Control law synthesis and stability robustness improvement using constrained optimization techniques

The present generic optimization procedure for a continuous or discrete control law (of arbitrary order), which will be applicable to a multiinput-multioutput system, is upon constraining used to satisfy conflicting design requirements on the mean-square responses and stability robustness at the plant input and output. The synthesis procedure is especially suitable for flexible airframes and large space structures modeled by a high-order state-space system of equations. Analytical expressions are obtained for the gradients of the cost function, together with design constraints on the mean-square response and minimum singular value.

Mukhopadhyay, Vivekananda↗

NASA NTRS1991

Cassini Titan Radar Mapper

The Cassini Titan Radar Mapper is a multimode radar instrument designed to probe the optically inaccessible surface of Titan, Saturn's largest moon. The instrument is to be included in the payload of the Cassini Saturn Mission, scheduled for launch in 1995. The individual modes of Cassini Radar Mapper will allow topographic mapping and surface imaging at few hundred meters resolution. The requirements that lay behind the design are briefly discussed, and the configuration and capability of the instrument are described. The present limited knowledge of Titan's surface and the measurement requirements imposed on the radar instrument are addressed. Also discussed are the Cassini mission and the projected orbits, which imposed another set of design constraints that led to the multitude of modes and to an unconventional antenna configuration. The antenna configuration and the different radar modes are described.

Elachi, Charles↗

NASA NTRS1991

A comparison of arrow, trapezoidal and M wing concepts using a Mach 2 supersonic cruise transport mission

The present analytic study of the potential performance of SST configurations radically differing from arrow-winged designs in lifting surface planform geometry gives attention to trapezoidal-wing and M-wing configurations; the trapezoidal wing is used as the baseline in the performance comparisons. The design mission was all-supersonic (Mach 2), carrying 248 passengers over a 5500 nautical-mile range. Design constraints encompassed approach speed, TO&L field length, and engine-out second-segment climb and missed-approach performance. Techniques for improving these configurations are discussed.

Martin, Glenn L.↗

NASA NTRS1991

Sliding backshorts for planar circuits

An adjustable planar imbedding circuit based on coplanar transmission lines is presented to deal with the impedance mismatch associated with the use of the Superconductor-Insulator-Superconductor tunnel junction. The planar embedding circuit is developed with movable noncontacting shorting elements that consist of thin metallic plates with optimized arrangements of rectangular holes. The rectangular holes are placed along the insulated metallic transmission line to provide a periodic variation of the line impedance. A large reflection coefficient is demonstrated with a scale model of the sliding backshort, and values of more than -0.5 dB are reported. The shorting elements are incorporated into a low-frequency tuning circuit to test the practical tuning ranges. The backshort can be used to fashion tuning stubs with variable post-fabrication electrical lengths which relaxes the design constraints of planar integrated circuits.

Lubecke, Victor M.↗

NASA NTRS1992

The solar X-ray/cosmic gamma-ray burst experiment aboard Ulysses

The scientific objectives of the Ulysses solar X-ray/cosmic gamma-ray burst experiment, and the unique features of the Ulysses mission which will help to achieve them are described. After a discussion of the special design constraints imposed by the mission, the sensor systems, consisting of two CsI scintillators and two Si surface barrier detectors covering the energy range 5-150 keV are described. Their operating modes and inflight performance are also given.

Hurley, K.↗

NASA NTRS1992

NASA advanced design program: Analysis, design, and construction of a solar powered aircraft

Increase in energy demands coupled with rapid depletion of natural energy resources have deemed solar energy as the most logical alternative source of power. The major objective of this project was to build a solar powered remotely controlled aircraft to demonstrate the feasibility of solar energy as an effective, alternate source of power. The final design was optimized for minimum weight and maximum strength of the structure. These design constraints necessitated a carbon fiber composite structure. Surya is a lightweight, durable aircraft capable of achieving level flight powered entirely by solar cells.

Chan, Agnes↗

NASA NTRS1993

C-SIDE: The control-structure interaction demonstration experiment

The Control-Structure Interaction Demonstration Experiment (C-SIDE) is sponsored by the Electro-Optics and Cryogenics Division of Ball Aerospace Systems Group. Our objective is to demonstrate methods of solution to structure control problems utilizing currently available hardware in a system that is an extension of our corporate experience. The larger space structures with which Ball has been associated are the SEASAT radar antenna, Shuttle Imaging Radar (SIR) -A, -B and -C antennas and the Radarsat spacecraft. The motivation for the C-SIDE configuration is to show that integration of active figure control in the radar's system-level design can relieve antenna mechanical design constraints. This presentation is primarily an introduction to the C-SIDE testbed. Its physical and functional layouts, and major components are described. The sensor is of special interest as it enables direct surface figure measurements from a remote location. The Remote Attitude Measurement System (RAMS) makes high-rate, unobtrusive measurements of many locations, several of which may be collocated easily with actuators. The control processor is a 386/25 executing a reduced order model-based algorithm with provision for residual mode filters to compensate for structure interaction. The actuators for the ground demonstration are non-contacting, linear force devices. Results presented illustrate some basic characteristics of control-structure interaction with this hardware. The testbed will be used for evaluation of current technologies and for research in several areas. A brief indication of the evolution of the C-SIDE is given at the conclusion.

Mohl, James B.↗

NASA NTRS1991

Intelligent systems technology infrastructure for integrated systems

A system infrastructure must be properly designed and integrated from the conceptual development phase to accommodate evolutionary intelligent technologies. Several technology development activities were identified that may have application to rendezvous and capture systems. Optical correlators in conjunction with fuzzy logic control might be used for the identification, tracking, and capture of either cooperative or non-cooperative targets without the intensive computational requirements associated with vision processing. A hybrid digital/analog system was developed and tested with a robotic arm. An aircraft refueling application demonstration is planned within two years. Initially this demonstration will be ground based with a follow-on air based demonstration. System dependability measurement and modeling techniques are being developed for fault management applications. This involves usage of incremental solution/evaluation techniques and modularized systems to facilitate reuse and to take advantage of natural partitions in system models. Though not yet commercially available and currently subject to accuracy limitations, technology is being developed to perform optical matrix operations to enhance computational speed. Optical terrain recognition using camera image sequencing processed with optical correlators is being developed to determine position and velocity in support of lander guidance. The system is planned for testing in conjunction with Dryden Flight Research Facility. Advanced architecture technology is defining open architecture design constraints, test bed concepts (processors, multiple hardware/software and multi-dimensional user support, knowledge/tool sharing infrastructure), and software engineering interface issues.

Lum, Henry↗

NASA NTRS1993

An improved linear ion trap physics package

This article describes an improvement in the architecture of the physics package used in the Linear Ion Trap (LIT)-based frequency standard recently developed at JPL. This new design is based on the observation that ions can be moved along the axis of an LIT by applied dc voltages. The state selection and interrogation region can be separated from the more critical microwave resonance region where the multiplied local oscillator signal is compared with the stable atomic transition. This separation relaxes many of the design constraints of the present units. Improvements include increased frequency stability and a substantial reduction in size, mass, and cost of the final frequency standard.

Prestage, J. D.↗

NASA NTRS1993

Satellite Test Assistant Robot (STAR)

A three-year, three-phase program to demonstrate the applicability of telerobotic technology to the testing of satellites and other spacecraft has been initiated. Specifically, the objectives are to design, fabricate, and install into the JPL 25-ft. Space Simulator (SS) a system that will provide the capability to view test articles from all directions in both the visible and infrared (IR) spectral regions, to automatically map the solar flux intensity over the entire work volume of the chamber, and to provide the capability for leak detection. The first year's work, which provides a vertically mobile viewing platform equipped with stereo cameras, will be discussed. Design constraints and system implementation approaches mandated by the requirements of thermal vacuum operation will be emphasized.

Mcaffee, D. A.↗

NASA NTRS1992

A NASA study of the impact of technology on future sea based attack aircraft

A conceptual aircraft design study was recently completed evaluating carrier-based, subsonic attack aircraft using contemporary and future technology assumptions. The study examined a configuration matrix that was made up of light and medium bomb loads, one and two man crews, internal and external weapons carriage, as well as conventional and flying wing planforms. Use of common technology assumptions, engine cycle simulation code, design mission, and consistent application of methods allow for direct comparison of the aircraft. This paper describes the design study ground rules and the aircraft designed. The aircraft descriptions include weights, dimensions, layout, design mission, design constraints, maneuver performance, and fallout mission performance. The strengths, and weaknesses of each aircraft are highlighted.

Hahn, Andrew S.↗

NASA NTRS1992

Environmental testing of high Tc superconductive thermal isolators for space-borne cryogenic detector systems

Thick films of superconductive material on low thermal conductivity substrates (e.g., yttria-stabilized zirconia and fused silica) are considered as a replacement for the existing electrical connections between the detector array and data acquisition and storage electronics in the cryogenic detector systems being developed by NASA. The paper describes some of the design constraints on the superconducting device and presents results of a preliminary analysis of the effects of vibration, gamma irradiation, and long-term exposure to high vacuum and liquid nitrogen encountered in operating such a device in space.

Wise, Stephanie A.↗

NASA NTRS1994

Program For Optimization Of Nuclear Rocket Engines

NOP is versatile digital-computer program devoloped for parametric analysis of beryllium-reflected, graphite-moderated nuclear rocket engines. Facilitates analysis of performance of engine with respect to such considerations as specific impulse, engine power, type of engine cycle, and engine-design constraints arising from complications of fuel loading and internal gradients of temperature. Predicts minimum weight for specified performance.

Plebuch, R. K.↗

NASA NTRS1993

High resolution SAR applications and instrument design

The Synthetic Aperture Radar (SAR) has viewed, in the last two years, a huge increment of interest from many preset and potential users. The good spatial resolution associated to the all weather capability lead to considering SAR not only a scientific instrument but a tool for verifying and controlling the daily human relationships with the Earth Environment. New missions were identified for SAR as spatial resolution became lower than three meters: disasters, pollution, ships traffic, volcanic eruptions, earthquake effect are only a few of the possible objects which can be effectively detected, controlled and monitored by SAR mounted on satellites. High resolution radar design constraints and dimensioning are discussed.

Dionisio, C.↗

NASA NTRS1991

Ultra low power CMOS technology

This paper discusses the motivation, opportunities, and problems associated with implementing digital logic at very low voltages, including the challenge of making use of the available real estate in 3D multichip modules, energy requirements of very large neural networks, energy optimization metrics and their impact on system design, modeling problems, circuit design constraints, possible fabrication process modifications to improve performance, and barriers to practical implementation.

Burr, J.↗

NASA NTRS1992

Solar powered multipurpose remotely powered aircraft

Increase in energy demands coupled with rapid depletion of natural energy resources have deemed solar energy as an attractive alternative source of power. The focus was to design and construct a solar powered, remotely piloted vehicle to demonstrate the feasibility of solar energy as an effective, alternate source of power. The final design included minimizing the power requirements and maximizing the strength-to-weight and lift-to-drag ratios. Given the design constraints, Surya (the code-name given to the aircraft), is a lightweight aircraft primarily built using composite materials and capable of achieving level flight powered entirely by solar energy.

Alexandrou, A. N.↗

NASA NTRS1992

HSCT design for reduced sonic boom

The topics covered include the following: low sonic boom design perspective; design approach for reduced sonic boom; target sonic boom waveforms; airplane design for reduced sonic boom loudness; design procedure for low sonic boom; wing design and nacelle lift effects; area distributions and F-functions due to volume; fuselage area distributions; low sonic boom design, configuration 3B; sonic boom characteristics; sizing, performance, and noise characteristics; a summary of phase 3 configurations; impact of sonic boom design constraints; and wing loading considerations.

Haglund, George T.↗