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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 307 records · Page 17

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NASA NTRS1979

Magnetic suspension and pointing system

Apparatus for providing accurate pointing of instruments on a carrier vehicle and for providing isolation of the instruments from the vehicle's motion disturbances is presented. The apparatus includes two assemblies, with connecting interfaces, each assembly having a separate function. The first assembly is attached to the carrier vehicle and consists of an azimuth gimbal and an elevation gimbal which provide coarse pointing of the instruments by allowing two rotations of the instruments relative to the carrier vehicle. The second or vernier pointing assembly is made up of magnetic suspension and fine pointing actuators, roll motor segments, and an instrument mounting plate around which a continuous annular rim is attached which provides appropriate magnetic circuits for the actuators and the roll motor segments. The vernier pointing assembly provides six degree-of-freedom isolation from carrier motion disturbances.

Anderson, W. W.↗

NASA NTRS1972

Airborne electronically steerable phased array

The results are presented of the second stage of a program for the design and development of a phased array capable of simultaneous and separate transmission and reception of radio frequency signals at S-band frequencies. The design goals of this stage were the development of three major areas of interest required for the final prototype model. These areas are the construction and testing of the low-weight, full-scale 128-element array of antenna elements, the development of the RF manifold feed system, and the construction and testing of a working module containing diplexer and transmit and receive circuits.

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NASA NTRS1986

Measurement and application of fault latency

The time interval between the occurrence of a fault and the detection of the error caused by the fault is divided by the generation of that error into two parts: fault latency and error latency. Since the moment of error generation is not directly observable, all related works in the literature have dealt with only the sum of fault and error latencies, thereby making the analysis of their separate effects impossible. To remedy this deficiency, (1) a new methodology for indirectly measuring fault latency is presented; the distribution of fault latency is derived from the methodology; and (3) the knowledge of fault latency is applied to the analysis of two important examples. The proposed methodology has been implemented for measuring fault latency in the Fault-Tolerant Multiprocessor (FTMP) at the NASA Airlab. The experimental results show wide variations in the mean fault latencies of different function circuits within FTMP. Also, the measured distributions of fault latency are shown to have monotone hazard rates. Consequently, Gamma and Weibull distributions are selected for the least-squares fit as the distribution of fault latency.

Shin, K. G.↗

NASA NTRS2009

Microwave Temperature Profiler Mounted in a Standard Airborne Research Canister

Many atmospheric research aircraft use a standard canister design to mount instruments, as this significantly facilitates their electrical and mechanical integration and thereby reduces cost. Based on more than 30 years of airborne science experience with the Microwave Temperature Profiler (MTP), the MTP has been repackaged with state-of-the-art electronics and other design improvements to fly in one of these standard canisters. All of the controlling electronics are integrated on a single 4 ~5-in. (.10 ~13- cm) multi-layer PCB (printed circuit board) with surface-mount hardware. Improved circuit design, including a self-calibrating RTD (resistive temperature detector) multiplexer, was implemented in order to reduce the size and mass of the electronics while providing increased capability. A new microcontroller-based temperature controller board was designed, providing better control with fewer components. Five such boards are used to provide local control of the temperature in various areas of the instrument, improving radiometric performance. The new stepper motor has an embedded controller eliminating the need for a separate controller board. The reference target is heated to avoid possible emissivity (and hence calibration) changes due to moisture contamination in humid environments, as well as avoiding issues with ambient targets during ascent and descent. The radiometer is a double-sideband heterodyne receiver tuned sequentially to individual oxygen emission lines near 60 GHz, with the line selection and intermediate frequency bandwidths chosen to accommodate the altitude range of the aircraft and mission.

Mahoney, Michael J.↗

NASA NTRS1992

High-performance packaging for monolithic microwave and millimeter-wave integrated circuits

Packaging schemes were developed that provide low-loss, hermetic enclosure for advanced monolithic microwave and millimeter-wave integrated circuits (MMICs). The package designs are based on a fused quartz substrate material that offers improved radio frequency (RF) performance through 44 gigahertz (GHz). The small size and weight of the packages make them appropriate for a variety of applications, including phased array antenna systems. Packages were designed in two forms; one for housing a single MMIC chip, the second in the form of a multi-chip phased array module. The single chip array module was developed in three separate sizes, for chips of different geometry and frequency requirements. The phased array module was developed to address packaging directly for antenna applications, and includes transmission line and interconnect structures to support multi-element operation. All packages are fabricated using fused quartz substrate materials. As part of the packaging effort, a test fixture was developed to interface the single chip packages to conventional laboratory instrumentation for characterization of the packaged devices. The package and test fixture designs were both developed in a generic sense, optimizing performance for a wide range of possible applications and devices.

Shalkhauser, K. A.↗

NASA NTRS1992

RF tuning element

A device for tuning a circuit includes a substrate, a transmission line on the substrate that includes first and second conductors coupled to a circuit to be tuned, and a movable short-circuit for varying the impedance the transmission line presents to the circuit to be tuned. The movable short-circuit includes a dielectric layer disposed atop the transmission line and a distributed shorting element in the form of a conductive member that is configured to be slid along at least a portion of the transmission line atop the dielectric layer. The conductive member is configured to span the first and second conductors of the transmission line and to define at least a first opening that spans the two conductors so that the conductive member includes first and second sections separated by the first opening. The first and second sections of the conductive member combine with the first and second conductors of the transmission line to form first and second low impedance sections of transmission line, and the opening combines with the first and second conductors of the transmission line and the dielectric layer to form a first high impedance section of transmission line intermediate the first and second low impedance sections. Each of the first low impedance section and the first high impedance section have a length along the transmission line of approximately one-quarter wavelength, thus providing a periodic variation of transmission line impedance. That enhances reflection of rf power.

McGrath, William R.↗

NASA NTRS2004

Two-Stage Solenoid

A proposed design for a solenoid-based electromechanical actuator would provide greater starting force than does a comparable conventional design. As used here, starting force signifies the magnetic force exerted by the actuator at one end of its stroke when the gap in its magnetic circuit is the widest. A solenoid of conventional design exerts a large force when its gap is closed. The magnetic force decreases as the gap increases. Hence, typically, the starting force exerted by a conventional solenoid is small; depending upon the specific application, the starting force may even be insufficient to initiate closure. Whereas a conventional solenoid design provides for only one core, the proposed design calls for three cores, two of these being fixed to one another with a separate core between these two. Analysis shows that in comparison with conventional solenoids, the solenoids of the proposed design would not have a cost impact, could have longer operational lives, and exhibit larger forces in an open position. It was also reported that the proposed design could be extended to multiple-staged solenoid design, which would yield increased force in the middle of the stroke as well.

Myers, Jeremy↗

NASA NTRS2016

A Low-Power Correlator ASIC for Arrays with Many Antennas

We report the design of a new application-specific integrated circuit (ASIC) for use in radio telescope correlators. It supports the construction of correlators for an arbitrarily large number of signals. The ASIC uses an intrinsically low-power architecture along with design techniques and a process that together result in unprecedentedly low power consumption. The design is flexible in that it can support telescopes with almost any number of antennas N. It is intended for use in an "FX" correlator, where a uniform filter bank breaks each signal into separate frequency channels prior to correlation.

radio telescopes↗

NASA NTRS1983

Flow improvements in the circuit of the Langley 4- by 7-meter tunnel

In order to identify the most promising means for improving the flow in the Langley 4- by 7-Meter Tunnel, detailed surveys of the mean velocity profiles were measured in both the horizontal and vertical planes of symmetry at specific locations throughout the tunnel circuit. These data were obtained at test-section dynamic pressures of 1.53, 2.78, and 4.79 kPa (3 2, 58, and 100 psf, respectively) for tunnel operation in both the closed and open test-section configurations. In the base-line tunnel-flow surveys, the flow patterns near the end of the test section indicate a uniform mean velocity distribution. Downstream of the test section, unsymmetrical flow patterns result in low velocities along the inner walls and in flow separation along the inner wall of the diffuser upstream of the drive fan and along the outer wall of the large diffuser downstream of the drive fan. In order to correct these unsymmetrical flow patterns, a set of trailing-edge flaps attached to the five flow-control vanes located just downstream of the first corner were installed. These flaps were very successful in making the tunnel flow more symmetrical and in eliminating the regions of separation in the diffusers upstream and downstream of the drive fan.

Zachary T Applin↗

NASA NTRS1975

Results of the 1973 NASA/JPL balloon flight solar cell calibration program

High altitude balloon flights carried 37 standard solar cells for calibration above 99.5 percent of the earth's atmosphere. The cells were assembled into standard modules with appropriate resistors to load each cell at short circuit current. Each standardized module was mounted at the apex of the balloon on a sun tracker which automatically maintained normal incidence to the sun within 1.0 deg. The balloons were launched to reach a float altitude of approximately 36.6 km two hours before solar noon and remain at float altitude for two hours beyond solar noon. Telemetered calibration data on each standard solar cell was collected and recorded on magnetic tape. At the end of each float period the solar cell payload was separated from the balloon by radio command and descended via parachute to a ground recovery crew. Standard solar cells calibrated and recovered in this manner are used as primary intensity reference standards in solar simulators and in terrestrial sunlight for evaluating the performance of other solar cells and solar arrays with similar spectral response characteristics.

Yasui, R. K.↗

NASA NTRS2003

GPS Position and Heading Circuitry for Ships

Circuit boards that contain radio-frequency (RF) and digital circuitry have been developed by NASA to satisfy a requirement of the Port of Houston Authority for relatively inexpensive Global Positioning System (GPS) receivers that indicate the azimuthal headings as well as the positions of ships. The receiver design utilizes the unique architecture of the Mitel commercial chip-set, which provides for an accurate GPS-based heading-determination device. The major components include two RF front ends (each connected to a separate antenna), a surface-acoustic-wave intermediate-frequency filter between second- and third-stage mixers, a correlator, and a reduced-instruction- set computer. One of the RF front ends operates as a master, the other as a slave. Both RF front ends share a 10-MHz sinusoidal clock oscillator, which provides for more accurate carrier phase measurements between the two antennas. The outputs of the RF front ends are subjected to conventional GPS processing. The commercial-based chip-set design approach provides an inexpensive open architecture GPS platform, which can be used in developing and implementing unique GPS-heading and attitude-determination algorithms for specific applications. The heading is estimated from the GPS position solutions of the two antennas by an algorithm developed specifically for this application. If a third (and preferably a fourth) antenna were added, it would be possible to estimate the attitude of the GPS receiver in three dimensions instead of only its heading in a horizontal plane.

Cooke, Michael P.↗

NASA NTRS1976

Irradiate-anneal screening of total dose effects in semiconductor devices

An extensive investigation of irradiate-anneal (IRAN) screening against total dose radiation effects was carried out as part of a program to harden the Mariner Jupiter/Saturn 1977 (MJS'77) spacecraft to survive the Jupiter radiation belts. The method consists of irradiating semiconductor devices with Cobalt-60 to a suitable total dose under representative bias conditions and of separating the parts in the undesired tail of the distribution from the bulk of the parts by means of a predetermined acceptance limit. The acceptable devices are then restored close to their preirradiation condition by annealing them at an elevated temperature. IRAN was used when lot screen methods were impracticable due to lack of time, and when members of a lot showed a diversity of radiation response. The feasibility of the technique was determined by testing of a number of types of linear bipolar integrated circuits, analog switches, n-channel JFETS and bipolar transistors. Based on the results of these experiments a number of device types were selected for IRAN of flight parts in the MJS'77 spacecraft systems. The part types, screening doses, acceptance criteria, number of parts tested and rejected as well as the program steps are detailed.

Stanley, A. G.↗

NASA NTRS1991

Investigations of detail design issues for the high speed acoustic wind tunnel using a 60th scale model tunnel. Part 1: Tests with open circuits

This report summarizes the tests on the 1:60 scale model of the High Speed Acoustic Wind Tunnel (HSAWT) performed during the period of November 1989 to December 1990. Throughout the testing the tunnel was operated in the 'open circuit mode', that is when the airflow was induced by a powerful exhaust fan located outside the tunnel circuit. The tests were first performed with the closed test section and were subsequently repeated with the open test section. While operating with the open test section, a novel device, called the 'nozzle-diffuser,' was also tested in order to establish its usefulness of increasing pressure recovery in the first diffuser. The tests established the viability of the tunnel design. The flow distribution in each tunnel component was found acceptable and pressure recovery in the diffusers were found satisfactory. The diffusers appeared to operate without flow separation. All tests were performed at NASA LaRC.

Barna, P. Stephen↗

NASA NTRS2018

Development of an Optical Slice for an RF and Optical Software Defined Radio

A key component in the Integrated Radio and Optical Communications project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center (GRC) is the radio frequency (RF) and optical software defined radio (SDR). A NASA RF SDR might consist of a general purpose processor to run the Space Telecommunications Radio System (STRS) Architecture for radio command and control, a reconfigurable signal processing device such as a field programmable gate array (FPGA) which houses the waveform, and a digital to analog converter (DAC) for transmitting data. Prior to development, SDR architecture trades on how to combine the RF and optical elements were studied. A modular architecture with physically separate RF and optical hardware slices was chosen and the optical slice of an SDR was designed and developed. The Harris AppSTARTM platform, which consists of an FPGA processing platform with a mezzanine card targeted for RF communications, was used as the base platform in prototyping the optical slice. A serially concatenated pulse position modulation (SCPPM) optical waveform was developed. The waveform follows the standard described in the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Red Book. A custom optical mezzanine printed circuit board card was developed at NASA GRC for optical transmission. The optical mezzanine card replaces the DAC, which is used in the transmission of RF signals. This paper describes RF and optical SDR architecture trades, the Harris AppSTAR platform, the design of the SCPPM waveform, and the development of the optical mezzanine card.

Nappier, Jennifer M.↗

NASA NTRS2000

Novel Integrated Radial and Axial Magnetic Bearing

Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

Blumenstock, Kenneth A.↗

NASA NTRS2000

Novel Integration Radial and Axial Magnetic Bearing

Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

Blumenstock, Kenneth↗

NASA NTRS2010

NASA Tech Briefs, July 2010

Topics covered include: Wirelessly Interrogated Wear or Temperature Sensors; Processing Nanostructured Sensors Using Microfabrication Techniques; Optical Pointing Sensor; Radio-Frequency Tank Eigenmode Sensor for Propellant Quantity Gauging; High-Temperature Optical Sensor; Integral Battery Power Limiting Circuit for Intrinsically Safe Applications; Configurable Multi-Purpose Processor; Squeezing Alters Frequency Tuning of WGM Optical Resonator; Automated Computer Access Request System; Range Safety for an Autonomous Flight Safety System; Fast and Easy Searching of Files in Unisys 2200 Computers; Parachute Drag Model; Evolutionary Scheduler for the Deep Space Network; Modular Habitats Comprising Rigid and Inflatable Modules; More About N2O-Based Propulsion and Breathable-Gas Systems; Ultrasonic/Sonic Rotary-Hammer Drills; Miniature Piezoelectric Shaker for Distribution of Unconsolidated Samples to Instrument Cells; Lunar Soil Particle Separator; Advanced Aerobots for Scientific Exploration; Miniature Bioreactor System for Long-Term Cell Culture; Electrochemical Detection of Multiple Bioprocess Analytes; Fabrication and Modification of Nanoporous Silicon Particles; High-Altitude Hydration System; Photon Counting Using Edge-Detection Algorithm; Holographic Vortex Coronagraph; Optical Structural Health Monitoring Device; Fuel-Cell Power Source Based on Onboard Rocket Propellants; Polar Lunar Regions: Exploiting Natural and Augmented Thermal Environments; Simultaneous Spectral Temporal Adaptive Raman Spectrometer - SSTARS; Improved Speed and Functionality of a 580-GHz Imaging Radar; Bolometric Device Based on Fluxoid Quantization; Algorithms for Learning Preferences for Sets of Objects; Model for Simulating a Spiral Software-Development Process; Algorithm That Synthesizes Other Algorithms for Hashing; Algorithms for High-Speed Noninvasive Eye-Tracking System; and Adapting ASPEN for Orbital Express.

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NASA NTRS2018

Development of an Optical Slice for an RF and Optical Software Defined Radio

A key component in the Integrated Radio and Optical Communications project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center (GRC) is the radio frequency (RF) and optical software defined radio (SDR). A NASA RF SDR might consist of a general purpose processor to run the Space Telecommunications Radio System (STRS) Architecture for radio command and control, a reconfigurable signal processing device such as a field programmable gate array (FPGA) which houses the waveform, and a digital to analog converter for (DAC) transmitting data. Prior to development, SDR architecture trades on how to combine the RF and optical elements were studied. A modular architecture with physically separate RF and optical hardware slices was chosen and the optical slice of an SDR was designed and developed. The Harris AppSTAR("TM") platform, which consists of an FPGA processing platform with a mezzanine card targeted for RF communications, was used as the base platform in prototyping the optical slice. A serially concatenated pulse position modulation (SCPPM) optical waveform was developed. The waveform follows the standard described in the Consultative Committee for Space Data Systems (CCSDS) Optical Communions Coding and Synchronization Red Book. A custom optical mezzanine printed circuit board card was developed at NASA GRC for optical transmission. The optical mezzanine card replaces the DAC, which is used in the transmission of RF signals. This paper describes RF and optical SDR architecture trades, the Harris AppSTAR("TM") platform, the design of the SCPPM waveform, and the development of the optical mezzanine card.

optical communications↗