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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 973 records · Page 54

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NASA NTRS1980

Development of a preprototype thermoelectric integrated membrane evaporation subsystem for water recovery

A three-man urine water recovery preprototype subsystem using a new concept to provide efficient potable water recovery from waste fluids on extended duration space flights has been designed, fabricated, and tested. Low power, compactness, and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber polysulfone membrane evaporator with a thermoelectric heat pump. Application and integration of these key elements have solved problems inherent in previous reclamation subsystem designs. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than a waste liquid recirculation pump and a product water withdrawal pump. Tubular membranes provide structural integrity, improving on previous flat sheet membrane designs. A thermoelectric heat pump provides latent energy recovery.

Winkler, H. E.↗

NASA NTRS1980

The role of the real-time simulation facility, SIMFAC, in the design, development and performance verification of the Shuttle Remote Manipulator System (SRMS) with man-in-the-loop

The SIMFAC has played a vital role in the design, development, and performance verification of the shuttle remote manipulator system (SRMS) to be installed in the space shuttle orbiter. The facility provides for realistic man-in-the-loop operation of the SRMS by an operator in the operator complex, a flightlike crew station patterned after the orbiter aft flight deck with all necessary man machine interface elements, including SRMS displays and controls and simulated out-of-the-window and CCTV scenes. The characteristics of the manipulator system, including arm and joint servo dynamics and control algorithms, are simulated by a comprehensive mathematical model within the simulation subsystem of the facility. Major studies carried out using SIMFAC include: SRMS parameter sensitivity evaluations; the development, evaluation, and verification of operating procedures; and malfunction simulation and analysis of malfunction performance. Among the most important and comprehensive man-in-the-loop simulations carried out to date on SIMFAC are those which support SRMS performance verification and certification when the SRMS is part of the integrated orbiter-manipulator system.

Mccllough, J. R.↗

NASA NTRS1981

The algebraic theory of latent projectors in lambda matrices

Multivariable systems such as a finite-element model of vibrating structures, control systems, and large-scale systems are often formulated in terms of differential equations which give rise to lambda matrices. The present investigation is concerned with the formulation of the algebraic theory of lambda matrices and the relationship of latent roots, latent vectors, and latent projectors to the eigenvalues, eigenvectors, and eigenprojectors of the companion form. The chain rule for latent projectors and eigenprojectors for the repeated latent root or eigenvalues is given.

Denman, E. D.↗

NASA NTRS1983

Interactive analysis of a large aperture Earth observations satellite

A system level design and analysis has been conducted on an Earth Observation Satellite (EOS) system using the Interactive Design and Evaluation of Advanced Spacecraft (IDEAS) computer-aided design and analysis program. The IDEAS program consists of about 40 user-friendly technical modules and an interactive graphics display. The reflector support system and feed mast of the EOS spacecraft are constructed with box-truss structural concept, a lattice configuration which can be packaged for delivery in a single Shuttle flight and deployed in orbit. The deployed spacecraft consists of a 120-m by 60-m parabolic focal axis. The spacecraft was modeled for structural, thermal, and control systems analysis and structural elements were designed. On-orbit dynamic and thermal loading analyses were conducted; spacecraft weights and developmental and first unit costs were determined.

Wright, R. L.↗

NASA NTRS1982

Thermoelectric integrated membrane evaporation water recovery technology

The recently developed Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) offers a highly competitive approach to water recovery from waste fluids for future on-orbit stations such as the Space Operations Center. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber membrane evaporator with a thermoelectric heat pump. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than pumps and an accumulator, thus solving problems inherent in other reclamation subsystem designs. In an extensive test program, over 850 hours of operation were accumulated during which time high quality product water was recovered from both urine and wash water at an average steady state production rate of 2.2 pounds per hour.

Roebelen, G. J., Jr.↗

NASA NTRS1983

Interactive analysis of a large aperture Earth Observations Satellite

A system level design and analysis has been conducted on an Earth Observation Satellite (EOS) system using the Interactive Design and Evaluation of Advanced Spacecraft (IDEAS) computer-aided design and analysis program. The IDEAS program consists of about 40 user-friendly technical modules and an interactive graphics display. The reflector support system and feed mast of the EOS spacecraft are constructed with a box-truss structural concept, a lattice configuration which can be packaged for delivery in a single Shuttle flight and deployed in orbit. The deployed spacecraft consists of a 120-m by 60-m parabolic reflector, a 120-m-long support structure, and a 30-m feed arc beam on the focal axis. The spacecraft was modeled for structural, thermal, and control systems analysis and structural elements were designed. On-orbit dynamic and thermal loading analyses were conducted and spacecraft weights were determined.

Wright, R. L.↗

NASA NTRS1983

The ISPM experiment for spectral, composition and anistropy measurements of charged particles at low energie

The Heliosphere Instrument for Spectral, Composition, and Anisotropy at Low Energies (HI-SCALE) designed to measure interplanetary ions and electrons is described. Ions and electrons are detected by five separate solid-state detector telescopes oriented to give complete pitch angle coverage from the spinning spacecraft. Ion elemental abundances are determined by a telescope using a thin front detector element in a three-element telescope. Experiment operation is controlled by a microprocessor-based data system. Inflight calibration is provided by radioactive sources mounted on closable telescope covers. Ion and electron spectral information is determined using broad-energy-range rate channels, and a pulse-height analyzer for more detailed spectra. The instrument weighs 5.775 kg and uses 4.0 W power.

Lanzerotti, L. J.↗

NASA NTRS1982

Boeing Vertol noise reduction experience

Boeing Vertol Model 234, CH-47D and 347 tandem rotor helicopters demonstrate noise levels that comply with the overall noise standard requirements. The helicopters achieve these noise levels because they are, by design, free of impulsive noise in level flight and climb. Avoiding an impulsive noise signature is achieved by developing and applying configuration design criteria that eliminate blade vortex intersections and recognize advancing blade tip noise limitations in high speed forward flight. Airfoil design, rotor separation and rotor tipspeed selection all contribute to the noise control. Compliance with the approach element of the standards is marginal at best. The approach problem is not appreciably alleviated by reduced tipspeed and airfoil design. Since it is a single rotor phenomenon, it is not alleviated by rotor separation in the tandem configuration. Tip shapes may provide the answer, but to date this approach has not led to a satisfactory solution.

Walls, W. W.↗

NASA NTRS1985

Separate-contact phase-locked semiconductor laser arrays

The novel optoelectronic devices discussed, phase-locked semiconductor laser arrays with separate contacts can perform a variety of near field and far field pattern tailoring functions and control mutual coherence among array elements, as well as lasing wavelength selectivity and tunability. Attention is presently given to experimental results from such arrays, which indicate that the threshold currents of the 4-micron wide lasers employed are typically 60 mA. The separate contacts to each one of them are provided by means of two-level metallization.

Katz, J.↗

NASA NTRS1986

Variable Synthetic Capacitance

Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

Kleinberg, L. L.↗

NASA NTRS1984

The Large Deployable Reflector - A technology development challenge

The proposed Large Deployable Reflector (LDR) telescope is an astrophysical orbiting platform whose aperture is of the order of 20 m, and is dedicated to observations in the IR and sub-mm wavelengths. NASA is currently planning a 5-year technology development program that will allow the requisite hardware and software to reach the state required for economical and reliable implementation. A computer model simulation is envisioned toward this end that will encompass and integrate structural, thermal, control, optics, and systems program elements. Possession of the enabling technology is foreseen for the early 1990s.

Pittman, R. B.↗

NASA NTRS1987

Analysis of on-orbit thermal characteristics of the 15-meter hoop/column antenna

In recent years, interest in large deployable space antennae has led to the development of the 15 meter hoop/column antenna. The thermal environment the antenna is expected to experience during orbit is examined and the temperature distributions leading to reflector surface distortion errors are determined. Two flight orientations corresponding to: (1) normal operation, and (2) use in a Shuttle-attached flight experiment are examined. A reduced element model was used to determine element temperatures at 16 orbit points for both flight orientations. The temperature ranged from a minimum of 188 K to a maximum of 326 K. Based on the element temperatures, orbit position leading to possible worst case surface distortions were determined, and the subsequent temperatures were used in a static finite element analysis to quantify surface control cord deflections. The predicted changes in the control cord lengths were in the submillimeter ranges.

Andersen, Gregory C.↗

NASA NTRS1987

Advances and trends in computational structural mechanics

The development status and applicational range of techniques in computational structural mechanics (CSM) are evaluated with a view to advances in computational models for material behavior, discrete-element technology, quality assessment, the control of numerical simulations of structural response, hybrid analysis techniques, techniques for large-scale optimization, and the impact of new computing systems on CSM. Primary pacers of CSM development encompass prediction and analysis of novel materials for structural components, computational strategies for large-scale structural calculations, and the assessment of response prediction reliability together with its adaptive improvement.

Noor, Ahmed K.↗

NASA NTRS1988

Rotorcraft flight-propulsion control integration

The NASA Ames and Lewis Research Centers, in conjunction with the Army Research and Technology Laboratories have initiated and completed, in part, a joint research program focused on improving the performance, maneuverability, and operating characteristics of rotorcraft by integrating the flight and propulsion controls. The background of the program, its supporting programs, its goals and objectives, and an approach to accomplish them are discussed. Results of the modern control governor design of the T700 and the Rotorcraft Integrated Flight-Propulsion Control Study, which were key elements of the program, are also presented.

Mihaloew, James R.↗

NASA NTRS1988

Rotorcraft flight-propulsion control integration: An eclectic design concept

The NASA Ames and Lewis Research Centers, in conjunction with the Army Research and Technology Laboratories, have initiated and partially completed a joint research program focused on improving the performance, maneuverability, and operating characteristics of rotorcraft by integrating the flight and propulsion controls. The background of the program, its supporting programs, its goals and objectives, and an approach to accomplish them are discussed. Results of the modern control governor design of the General Electric T700 engine and the Rotorcraft Integrated Flight-Propulsion Control Study, which were key elements of the program, are also presented.

Mihaloew, James R.↗

NASA NTRS1988

Real time thermal imaging of high temperature semiconductor melts

A real time thermal imaging system with temperature resolution better than + or - 1 C and spatial resolution of better than 0.5 mm was developed and applied to the analysis of melt surface thermal field distributions in both Czochralski and liquid encapsulated Czochralski (LEC) growth configurations. The melt is viewed in near normal incidence by a high resolution charge coupled device camera to which is attached a very narrow bandpass filter. The resulting image is digitized and processed using a pipelined pixel processor operating at an effective 40 million operations per second thus permitting real time high frequency spatial and temporal filtering of the high temperature scene. A multi-pixel averaging algorithm was developed which permits localized, low noise sensing of temperature variations at any location in the hot zone as a function of time. This signial is used to implement initial elements of a feedforward growth control scheme which is aimed at reducing disturbances to the melt caused by the batch nature of the growth process. The effect of magnetic melt stabilization on radial melt temperature distributions was measured using this technique. Problems associated with residual internal reflections and non-optimized path geometry are discussed.

Wargo, Michael J.↗

NASA NTRS1988

The LDCM actuator for vibration suppression

A linear dc motor (LDCM) has been proposed as an actuator for the COFS I mast and the COFS program ground test Mini-Mast. The basic principles of operation of the LDCM as an actuator for vibration suppression in large flexible structures are reviewed. Because of force and stroke limitations, control loops are required to stabilize the actuator, which results in a non-standard actuator-plant configuration. A simulation model that includes LDCM actuator control loops and a finite element model of the Mast is described, with simulation results showing the excitation capability of the actuator.

Ide, Eric N.↗

NASA NTRS1988

A high fidelity real-time simulation of a small turboshaft engine

A high-fidelity component-type model and real-time digital simulation of the General Electric T700-GE-700 turboshaft engine were developed for use with current generation real-time blade-element rotor helicopter simulations. A control system model based on the specification fuel control system used in the UH-60A Black Hawk helicopter is also presented. The modeling assumptions and real-time digital implementation methods particular to the simulation of small turboshaft engines are described. The validity of the simulation is demonstrated by comparison with analysis-oriented simulations developed by the manufacturer, available test data, and flight-test time histories.

Ballin, Mark G.↗