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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS2006

NASA Tech Briefs, March 2006

Topics covered include: Medical Signal-Conditioning and Data-Interface System; Instruments for Reading Direct-Marked Data-Matrix Symbols; Processing EOS MLS Level-2 Data; Ground Processing of Data From the Mars Exploration Rovers; Estimating Total Electron Content Using 1,000+ GPS Receivers; NASA Solar Array Demonstrates Commercial Potential; Improved Control of Charging Voltage for Li-Ion Battery; Programmable Pulse-Position-Modulation Encoder; Wavelength-Agile External-Cavity Diode Laser for DWDM; Pattern-Recognition Processor Using Holographic Photopolymer; Submicrosecond Power-Switching Test Circuit; Three-Function Logic Gate Controlled by Analog Voltage; Integrated System for Autonomous Science; Montage Version 3.0; Utilizing AI in Temporal, Spatial, and Resource Scheduling; Satellite Image Mosaic Engine; Architecture for Control of the K9 Rover; HFGMC Enhancement of MAC/GMC; Automated Activation and Deactivation of a System Under Test; Cleaning Carbon Nanotubes by Use of Mild Oxygen Plasmas; Generating Aromatics From CO2 on Mars or Natural Gas on Earth; Attaching Thermocouples by Peening or Crimping; Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates; Generating Breathable Air Through Dissociation of N2O; High-Performance Scanning Acousto-Ultrasonic System; Correction for Thermal EMFs in Thermocouple Feedthroughs; Using Quasiparticle Poisoning To Detect Photons; Estimating Resolution Lengths of Hybrid Turbulence Models; Education and Training Module in Alertness Management; Cargo-Positioning System for Next-Generation Spacecraft; Micro-Imagers for Spaceborne Cell-Growth Experiments; Holographic Solar Photon Thrusters; Plasma-Based Detector of Outer-Space Dust Particles; and Generation of Data-Rate Profiles of Ka-Band Deep-Space Links.

Source record↗
NASA NTRS1987

Enhanced beam coupling modulation using the polarization properties of photorefractive GaAs

Observation is reported of a rotation in the polarization of the two photorefractive recording beams in GaAs for a configuration with the internally generated space-charge field along the line 110 crystallographic orientation. This rotation is a result of simultaneous constructive and destructive beam coupling in each beam for the optical electric field components along the two electrooptically induced principal dielectric axes of the crystal. By turning one of the beams on and off, the intensity of the other beam after the crystal and a polarization analyzer can be modulated by as much as 500 percent. This result is of particular importance for optical information processing applications.

Partovi, Afshin↗
NASA NTRS2005

Laser Metrology for an Optical-Path-Length Modulator

Laser gauges have been developed to satisfy requirements specific to monitoring the amplitude of the motion of an optical-path-length modulator that is part of an astronomical interferometer. The modulator includes a corner-cube retroreflector driven by an electromagnetic actuator. During operation of the astronomical interferometer, the electromagnet is excited to produce linear reciprocating motion of the corner-cube retroreflector at an amplitude of 2 to 4 mm at a frequency of 250, 750, or 1,250 Hz. Attached to the corner-cube retroreflector is a small pick-off mirror. To suppress vibrations, a counterweight having a mass equal to that of the corner-cube retroreflector and pick-off mirror is mounted on another electromagnetic actuator that is excited in opposite phase. Each gauge is required to measure the amplitude of the motion of the pick-off mirror, assuming that the motions of the pick-off mirror and the corner-cube retroreflector are identical, so as to measure the amplitude of motion of the corner- cube retroreflector to within an error of the order of picometers at each excitation frequency. Each gauge is a polarization-insensitive heterodyne interferometer that includes matched collimators, beam separators, and photodiodes (see figure). The light needed for operation of the gauge comprises two pairs of laser beams, the beams in each pair being separated by a beat frequency of 80 kHz. The laser beams are generated by an apparatus, denoted the heterodyne plate, that includes stabilized helium-neon lasers, acousto-optical modulators, and associated optical and electronic subsystems. The laser beams are coupled from the heterodyne plate to the collimators via optical fibers.

Gursel, Yekta↗
NASA NTRSDate not supplied

Voltage-Controlled Differential Faraday Rotation from FMNWs and Magnetoelastic Silicone-Nickel Composites

Differential Faraday rotation has been observed from strain-Differential Faraday rotation has been observed from strain-modulated magnetoelastic membranes using millimeter-wave polarimetry at 61.25 GHz. The membranes, consisting of aligned chains of nickel micro-particles embedded in silicone rubber, were manufactured using a roll-to-roll electromagnetic processing line, mounted onto piezoelectric ceramic annuli, and immersed in externally-generated static magnetic fields. Experiments were conducted in which the membranes were periodically stretched by operating the piezoelectric crystals close to their radial resonant frequencies—thereby modulating nickel particle density as well as magnetic material properties. A customized quasi-optical apparatus was used to determine the Faraday-rotation difference between the strained and unstrained states of the magnetoelastic membranes. Possible applications that could emerge from this polymer-based technology include nonreciprocal millimeter-wave components with voltage-controlled frequency response and bio-inspired geomagnetic sensors for GPS-denied navigation. Investigations were conducted to estimate the maximum attainable differential Faraday rotation and the minimum detectable static magnetic field.

nickel↗
NASA NTRS1997

Response of High Subsonic Jet to Nonaxisymmetric Disturbances

A model of sound generated in a high subsonic (Mach 0.9) circular jet is solved numerically in cylindrical coordinates for nonaxisymmetric disturbances. The jet is excited by transient mass injection by a finite duration pulse via a modulated ring source. The nonaxisymmetric solution is computed for long times after the initial disturbance has exited the computational domain. The long time behavior of the jet is dominated by vorticity and pressure disturbances generated at the nozzle lip and growing as they convect down-stream in the jet. These disturbances generate sound as they propagate. The primary non-axisymmetric effect that we simulate is that of a flapping mode where regions of high and low pressure alternate on opposite sides of the jet. The predominant feature of this mode is the appearance of relatively large deviations of the pressure from the ambient pressure on opposite sides of the jet and the convection of these regions downstream. We illustrate flow field, near field and far field data. Important nonaxisymmetric characteristics of the near and flow field disturbances include roughly periodic pressure elevations and depressions at opposite values of the azimuthal angle psi. These correspond to pressure disturbances propagating in the axial direction. The azimuthal velocity exhibits a sinusoidal dependence on psi with similar roughly periodic disturbances. For every azimuthal angle psi, the jet radiation peaks about 30 deg. from the jet axis, however there is now a pronounced dependence of the far field radiation pattern on psi.

Bayliss, A.↗
NASA NTRS1972

Development of a solid polymer electrolyte electrolysis cell module and ancillary components for a breadboard water electrolysis system

Solid polymer electrolyte technology in a water electrolysis system along with ancillary components to generate oxygen and hydrogen for a manned space station application are considered. Standard commercial components are utilized wherever possible. Presented are the results of investigations, surveys, tests, conclusions and recommendations for future development efforts.

Porter, F. J., Jr.↗
NASA NTRS1998

A Solar Thermophotovoltaic Electric Generator for Remote Power Applications

We have successfully demonstrated that a solar thermophotovoltaic (TPV) system with a SiC graybody emitter and the monolithic interconnected module device technology can be realized. A custom-designed solar cavity was made to house the SiC emitter and the Monolithic Integrated Module (MIM) strings for testing in a Stirling dish solar concentrator. Five 1x1-cm MIMs, with a bandgap of 0.74 eV, were mounted on a specially designed water-cooled heatsink and were electrically connected in series to form a string. Two such strings were fabricated and tested, as well as high-performance 2x2-cm MIMs with a bandgap of 0.74 eV. Very high output power density values between 0.82 and 0.90 W/ square cm were observed for an average emitter temperature of 1501 K.

Fatemi, Navid S.↗
NASA NTRS1998

A Solar Thermophotovoltaic Electric Generator for Remote Power Applications

We have successfully demonstrated that a solar thermophotovoltaic (TPV) system with a SiC graybody emitter and the monolithic interconnected module device technology can be realized. A custom-designed solar cavity was made to house the SiC emitter and the MIM strings for testing in a Stirling dish solar concentrator. Five 1x1-cm MIMs, with a bandgap of 0.74 eV,were mounted on a specially designed water-cooled heatsink and were electrically connected in series to form a string. Two such strings were fabricated and tested, as well as high-performance 2x2-cm MIMs with a bandgap of 0.74 eV. Very high output power density values between 0.82 and 0.90 W/sq cm were observed for an average emitter temperature of 1501 K.

Fatemi, Navid S.↗
NASA NTRS2014

Calibration of International Space Station (ISS) Node 1 Vibro-Acoustic Model-Report 2

Reported here is the capability of the Energy Finite Element Method (E-FEM) to predict the vibro-acoustic sound fields within the International Space Station (ISS) Node 1 and to compare the results with simulated leak sounds. A series of electronically generated structural ultrasonic noise sources were created in the pressure wall to emulate leak signals at different locations of the Node 1 STA module during its period of storage at Stennis Space Center (SSC). The exact sound source profiles created within the pressure wall at the source were unknown, but were estimated from the closest sensor measurement. The E-FEM method represents a reverberant sound field calculation, and of importance to this application is the requirement to correctly handle the direct field effect of the sound generation. It was also important to be able to compute the sound energy fields in the ultrasonic frequency range. This report demonstrates the capability of this technology as applied to this type of application.

Zhang, Weiguo↗
NASA NTRS2020

A Computer Program to Generate Tri-Truss Structures for On- and Off-Axis Telescope Dishes

The size of traditional space telescopes has been limited by the size of the launch vehicle shroud size. Designs of space telescopes with larger apertures and greater resolving power can be achieved with multiple launches incorporating modular elements and in-space assembly techniques. The modular elements of an in-space assembled telescope include segmented reflectors supported on an assembled truss structure. The modular truss structures are most commonly based on a tessellation of triangles across a reflector’s surface, and in some cases utilize deployable trusses to simplify in-space assembly. One design effort, the in-Space Assembled Telescope (iSAT), proposes the use of deployable “tri-truss” modules to form an off-set parabolic reflector. In support of the iSAT, a computer program was developed to tesselate tri-truss modules over a parabolic surface. Based on several user-defined variables, the program renders a tri-truss structure and generates a stereolithography file of the generated truss structure for three dimensional (3D) printing. In addition, due to the importance of packing efficiency for space launch, the program attempts to minimize unnecessary differences in strut lengths using a grade parameter based on previous work.

Structures↗
NASA NTRS1980

NASA PERT time II

Program Evaulation and Review Technique (PERT) is disciplined management technique involving computer processing. NASA PERT Time 11 gives project manager insight into current and future project development and forewarns of potential problems. Program utilizes modular technique. Module is "fragnet"; once aspects of project are described in terms of fragnets, control network is automatically generated. Program is written in FORTRAN IV and OS Assembler for batch execution and has been implemented on IBM 370.

Bainbridge, R. C.↗
NASA NTRS1980

Solar cell system having alternating current output

A monolithic multijunction solar cell was modified by fabricating an integrated circuit inverter on the back of the cell to produce a device capable of generating an alternating current output. In another embodiment, integrated curcuit power conditioning electronics was incorporated in a module containing a solar cell power supply.

Evans, J. C., Jr.↗
NASA NTRS1984

Analytical Models

A system-level design and analysis model was developed. This model was conceived to have several key elements: a solar pond thermodynamic performance model, a power generation subsystem model, and an economic analysis element. The basic approach was to create these elements or modules and refine them on an individual basis yet retain the capability to easily couple them into a full system design model. This building block approach allows for maximum flexibility and substitution of refined descriptions as the technology develops. A general overview of interconnecting these subsystem models is presented. The primary program control element will perform the administrative functions of data input, data output, information storage and transfer, and sequential calling of the subsystem models. From the point of view of the requirements of a system design model, a power conversion subsystem model was developed. The goal of the effort was a preliminary subsystem model compatible with the solar pond subsystem model so that a first order system simulation analysis could be performed.

Source record↗
NASA NTRS1990

Digital Controller For Emergency Beacon

Prototype digital controller intended for use in 406-MHz emergency beacon. Undergoing development according to international specifications, 406-MHz emergency beacon system includes satellites providing worldwide monitoring of beacons, with Doppler tracking to locate each beacon within 5 km. Controller turns beacon on and off and generates binary codes identifying source (e.g., ship, aircraft, person, or vehicle on land). Codes transmitted by phase modulation. Knowing code, monitor attempts to communicate with user, monitor uses code information to dispatch rescue team appropriate to type and locations of carrier.

Ivancic, William D.↗
NASA NTRS1991

Emergency locating transmitter

A transmitter generates three signals for sequential transmission. These signal are an unmodulated r.f. carrier, a r.f. carrier amplitude modulated by a first audio frequency waveform and a r.f. carrier amplitude modulated by a second audio frequency waveform which is distinguishable from the first and which may be employed as a means for identifying a particular transmitter. The composite, sequentially transmitted signal may be varied in terms of the individual signal transmission sequence, the duration of the individual signals, overall composite signal repetition rate and the frequency of the second audio waveform. Various combinations of signal variations may be employed to transmit different information.

Wren, Paul E.↗
NASA NTRS1991

Wavelength-multiplexed fiber-optic position encoder for aircraft control systems

NASA-Lewis has developed wavelength-multiplexed digital position fiber-optics transducers for use in aircraft control systems. A prototype LED-powered rotary encoder for a commercial aircraft turbofan engine is under construction which will have 8-bit resolution and an operational temperature in the 90 C range. A compact electrooptics module is also under development which will be able to withstand gas turbine environments. A second-generation device will incorporate integrated photonics technologies to increase optical power margin.

Beheim, Glenn↗
NASA NTRS1993

A two-dimensional model with coupled dynamics, radiation, and photochemistry. 1: Simulation of the middle atmosphere

Spatial and seasonal distribution of ozone and other trace gases are simulated using a interactive two-dimensional model of the stratosphere updated to include full gas phase chemistry. The model consists of a primitive equation dynamics module, a full radiative transfer scheme, and a comprehensive gas phase chemistry module. The circulation is derived from heating rates in the stratosphere that are calculated using model-generated ozone. In the troposphere, parameterized heating rates are adopted. The eddy momentum flux divergence in the zonal mean momentum equation is given by the eddy fluxes of potential vorticity. Eddy fluxes of potential vorticity and tracers are parameterized using a set of predetermined diffusion coefficients. The adopted values for K(sub yy), show a hemispherical asymmetry in that the values in the lower stratosphere are consistently smaller in the southern hemisphere. The asymmetry in K(sub yy) and in the parameterization of the tropospheric heating rate results in an asymmetry in the circulation giving rise to unique signatures in the trace gas distributions. The model successfully simulates the observed asymmetry in the column abundance of the springtime ozone maxima between northern and southern hemisphere. Results for other trace gases are in agreement with the gross observed features although specific differences exist.

Ko, Malcolm K. W.↗
NASA NTRS1999

Global Modeling of Mineral Dust and its Optical Thickness

Global distribution of dust in the atmosphere has been simulated using the NASA Goddard chemical transport model (GEOS-CTM) to help retrieve the aerosol optical thickness from TOMS absorbing aerosol index. The model contains a dust module which accounts for sources and removal processes. The transport is driven by the assimilated meteorological fields generated by the NASA Goddard Earth Observing System Data Assimilation System (GEOS DAS). One of the key parameters, in the retrieval algorithm of optical thickness from Total Ozone Mapping Spectrometer (TOMS) data, is the vertical profile of aerosols. During the period 10- 19 September 1994, Lidar on-space Technology Experiment (LITE) was flown on space shuttle Discovery. The 53 hours of data collected cover the lower atmosphere from the earth surface to 20 kilometers altitude and from 57 N to 57 S with a high resolution of about 15 meters. The model results are compared with LITE data over the source regions of dust (Africa, Middle East, Asia, Australia) and in the remote troposphere (Atlantic and Pacific). The simulated horizontal distribution is compared with TOMS absorbing aerosol index. Finally the calculated optical thickness will be assessed with ground based sun-photometers (AERONET).

Ginoux, Paul A.↗