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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

A faint-object grism spectrograph with multiple slits and CCD detector

A high-efficiency spectrograph for research on faint astronomical objects has been successfully built and is in regular use on the Multiple-Mirror Telescope (MMT). It is equipped with a motorized multi-slit mechanism to allow simultaneous observations of several objects. The combination of high throughput, multiple object capability, and low-noise CCD detector has allowed routine work to be extended to objects of V magnitude 23 and fainter.

Geary, John C.↗
NASA NTRS1987

Monolithic Microwave Integrated Circuit (MMIC) technology for space communications applications

Future communications satellites are likely to use gallium arsenide (GaAs) monolithic microwave integrated-circuit (MMIC) technology in most, if not all, communications payload subsystems. Multiple-scanning-beam antenna systems are expected to use GaAs MMIC's to increase functional capability, to reduce volume, weight, and cost, and to greatly improve system reliability. RF and IF matrix switch technology based on GaAs MMIC's is also being developed for these reasons. MMIC technology, including gigabit-rate GaAs digital integrated circuits, offers substantial advantages in power consumption and weight over silicon technologies for high-throughput, on-board baseband processor systems. For the more distant future pseudomorphic indium gallium arsenide (InGaAs) and other advanced III-V materials offer the possibility of MMIC subsystems well up into the millimeter wavelength region. All of these technology elements are in NASA's MMIC program. Their status is reviewed.

Connolly, Denis J.↗
NASA NTRS1987

Telemetry handling on the Space Station data management system

This paper examines the impact of telemetry handling on the design of the onboard networks that are part of the Space Station Data Management System (DMS). An architectural approach to satisfying the DMS requirement for support of the high throughput needed for telemetry transport and for servicing distributed computer systems is discussed. Several of the functionality vs. performance tradeoffs that must be made in developing an optimized mechanism for handling telemetry data in the DMS are considered.

Whitelaw, Virginia A.↗
NASA NTRS1988

Figured grazing incidence mirrors from reheated float glass

High throughput grazing incidence mirrors have been fabricated from float glass using a new inexpensive technique. An array of twelve such mirrors including grazing angles from 3 to 15 deg has been fabricated and tested. Optical measurement of this array shows a line spread function of 6.3-min of arc FWHM with 90 percent of the energy enclosed within 13 min of arc. Three-mirror arrays are used to provide one-dimensional focusing for a diffuse extreme ultraviolet spectrometer. This paper presents the fabrication techniques and testing procedures used, as well as the mirror performance results.

Labov, Simon E.↗
NASA NTRS1989

Balanced-Load Real-Time Multiprocessor System

Modularity and parallelism provide tolerance to faults and high throughput capacity. System, called MAX, is network of interconnected computers. MAX cluster consists of group of modules - each semiautonomous computer. Modules connected to each other and to other clusters by global bus and circuit-switched communication mesh.

Rasmussen, Robert D.↗
NASA NTRS1989

The X-ray Timing Explorer Mission

The technical aspects of the X-ray Timing Explorer (XTE) mission are described with particular attention paid to the current scientific problems it will address. It features a low-background, continuous 2-200 keV response with large areas. Rapid response (in hours) to observing opportunities is obtained by virtue of a scanning all-sky monitor, rapid spacecraft maneuverability, and rapid response in the control center. XTE will carry out detailed, energy-resolved studies of phenomena close to neutron stars and black holes utilizing XTE's submillisecond timing, its high telemetry rates, and the high throughput of its data system.

Rothschild, Richard E.↗
NASA NTRS1988

Recursive least squares estimation and Kalman filtering by systolic arrays

One of the most promising new directions for high-throughput-rate problems is that based on systolic arrays. In this paper, using the matrix-decomposition approach, a systolic Kalman filter is formulated as a modified square-root information filter consisting of a whitening filter followed by a simple least-squares operation based on the systolic QR algorithm. By proper skewing of the input data, a fully pipelined time and measurement update systolic Kalman filter can be achieved with O(n squared) processing cells, resulting in a system throughput rate of O (n).

Chen, M. J.↗
NASA NTRS1990

The X-ray Timing Explorer

The capabilities of the X-ray Timing Explorer (XTE) are described with particular attention paid to current scientific problems it will address, from galactic neutron star systems to active galactic nuclei. It features a low-background continuous 2-200 keV response with large apertures (a 0.63 sq m proportional counter array and a 0.16 sq m dual rocking NaI/CsI scintillation array). Rapid response (in hours) to temporal phenomena, e.g., transients, is obtained by virtue of a scanning all-sky monitor and rapid maneuverability. The XTE will carry out detailed energy-resolved studies of phenomena close to neutron stars (e.g., quasi-periodic oscillations) because of its submillisecond timing (to 10 microsec), its high telemetry rates (to 256 kbs), and the high throughput of its data system (to greater than about (200,000 c/sec).

Bradt, H. V.↗
NASA NTRS1990

The Space Telescope SI C&DH system

The Hubble Space Telescope Scientific Instrument Control and Data Handling Subsystem (SI C&DH) is designed to interface with five scientific instruments of the Space Telescope to provide ground and autonomous control and collect health and status information using the Standard Telemetry and Command Components (STACC) multiplex data bus. It also formats high throughput science data into packets. The packetized data is interleaved and Reed-Solomon encoded for error correction and Pseudo Random encoded. An inner convolutional coding with the outer Reed-Solomon coding provides excellent error correction capability. The subsystem is designed with the capacity for orbital replacement in order to meet a mission life of fifteen years. The spacecraft computer and the SI C&DH computer coordinate the activities of the spacecraft and the scientific instruments to achieve the mission objectives.

Gadwal, Govind R.↗
NASA NTRS1991

Scanning X-Ray Or Extreme-Ultraviolet Monochromator

Wavelength of peak transmission of proposed high-throughput, narrow-band-pass x-ray or extreme-ultraviolet monochromator continuously adjustable. Essential filtering and reflecting components designed according to principles described in "Compact X-Ray and Extreme-Ultraviolet Monochromator" (MFS-28499). However, angle of incidence varied to change wavelength of Bragg reflection.

Hoover, Richard↗
NASA NTRS1991

Neurocontrol and fuzzy logic: Connections and designs

Artificial neural networks (ANNs) and fuzzy logic are complementary technologies. ANNs extract information from systems to be learned or controlled, while fuzzy techniques mainly use verbal information from experts. Ideally, both sources of information should be combined. For example, one can learn rules in a hybrid fashion, and then calibrate them for better whole-system performance. ANNs offer universal approximation theorems, pedagogical advantages, very high-throughput hardware, and links to neurophysiology. Neurocontrol - the use of ANNs to directly control motors or actuators, etc. - uses five generalized designs, related to control theory, which can work on fuzzy logic systems as well as ANNs. These designs can copy what experts do instead of what they say, learn to track trajectories, generalize adaptive control, and maximize performance or minimize cost over time, even in noisy environments. Design tradeoffs and future directions are discussed throughout.

Werbos, Paul J.↗
NASA NTRS1991

Remote sensing of Earth's atmosphere and surface using a digital array scanned interferometer: A new type of imaging spectrometer

The capabilities of the digital array scanned interferometer (DASI) class of instruments for measuring terrestrial radiation fields over the visible to mid-infrared are evaluated. DASI's are capable of high throughput, sensitivity and spectral resolution and have the potential for field-of-view spatial discrimination (an imaging spectrometer). The simplicity of design and operation of DASI's make them particularly suitable for field and airborne platform based remote sensing. The long term objective is to produce a versatile field instrument which may be applied toward a variety of atmospheric and surface studies. The operation of DASI and its advantages over other spectrometers are discussed.

Hammer, Philip D.↗
NASA NTRS1990

A class of systolizable IIR digital filters and its design for proper scaling and minimum output roundoff noise

A class of infinite impulse response (IIR) digital filters with a systolizable structure is proposed and its synthesis is investigated. The systolizable structure consists of pipelineable regular modules with local connections and is suitable for VLSI implementation. It is capable of achieving high performance as well as high throughput. This class of filter structure provides certain degrees of freedom that can be used to obtain some desirable properties for the filter. Techniques of evaluating the internal signal powers and the output roundoff noise of the proposed filter structure are developed. Based upon these techniques, a well-scaled IIR digital filter with minimum output roundoff noise is designed using a local optimization approach. The internal signals of all the modes of this filter are scaled to unity in the l2-norm sense. Compared to the Rao-Kailath (1984) orthogonal digital filter and the Gray-Markel (1973) normalized-lattice digital filter, this filter has better scaling properties and lower output roundoff noise.

Lei, Shaw-Min↗
NASA NTRS1991

Development of the Single Graded Groove high-performance heat pipe

This paper describes the development of a new nonarterial heat pipe with a nominal transport capability of 100,000 W in. Data are presented for one-g transport capability as a function of tilt and working fluid quantity. The transport capability agrees well with theoretical predictions. The LMSC Graded Groove Heat Pipe exhibits the high throughput and excellent heat transfer characteristics of earlier arterial designs such as the LMSC Tapered Artery Heat Pipe. At the same time, it suffers none of the priming difficulties associated with the arterial designs.

Ambrose, J. H.↗
NASA NTRS1991

A class of least-squares filtering and identification algorithms with systolic array architectures

A unified approach is presented for deriving a large class of new and previously known time- and order-recursive least-squares algorithms with systolic array architectures, suitable for high-throughput-rate and VLSI implementations of space-time filtering and system identification problems. The geometrical derivation given is unique in that no assumption is made concerning the rank of the sample data correlation matrix. This method utilizes and extends the concept of oblique projections, as used previously in the derivations of the least-squares lattice algorithms. Exponentially weighted least-squares criteria are considered for both sliding and growing memory.

Kalson, Seth Z.↗
NASA NTRS1992

Reconfigurable Fuzzy Cell

Flexible sensor-signal-processing circuit responds rapidly. Reconfigurable fuzzy cell provides real-time, high-throughput, interrupt-driven, multiplex conversion of sample raw signals from sensors into their grade of membership for use in fuzzy-logic control system.

Salazar, George A.↗
NASA NTRS1992

The link evaluation terminal for the advanced communications technology satellite experiments program

The experimental NASA satellite, Advanced Communications Technology Satellite (ACTS), introduces new technology for high throughput 30 to 20 GHz satellite services. Contained in a single communication payload is both a regenerative TDMA system and multiple 800 MHz 'bent pipe' channels routed to spot beams by a switch matrix. While only one mode of operation is typical during any experiment, both modes can operate simultaneously with reduced capability due to sharing of the transponder. NASA-Lewis instituted a ground terminal development program in anticipation of the satellite launch to verify the performance of the switch matrix mode of operations. Specific functions are built into the ground terminal to evaluate rain fade compensation with uplink power control and to monitor satellite transponder performance with bit error rate measurements. These functions were the genesis of the ground terminal's name, Link Evaluation Terminal, often referred to as LET. Connectors are included in LET that allow independent experimenters to run unique modulation or network experiments through ACTS using only the RF transmit and receive portions of LET. Test data indicate that LET will be able to verify important parts of ACTS technology and provide independent experimenters with a useful ground terminal. Lab measurements of major subsystems integrated into LET are presented. Bit error rate is measured with LET in an internal loopback mode.

May, Brian D.↗
NASA NTRS1991

The Next Century Astrophysics Program

The Astrophysics Division within the NASA Office of Space Science and Applications (OSSA) has defined a set of major and moderate missions that are presently under study for flight sometime within the next 20 years. These programs include the: Advanced X Ray Astrophysics Facility; X Ray Schmidt Telescope; Nuclear Astrophysics Experiment; Hard X Ray Imaging Facility; Very High Throughput Facility; Gamma Ray Spectroscopy Observatory; Hubble Space Telescope; Lunar Transit Telescope; Astrometric Interferometer Mission; Next Generation Space Telescope; Imaging Optical Interferometer; Far Ultraviolet Spectroscopic Explorer; Gravity Probe B; Laser Gravity Wave Observatory in Space; Stratospheric Observatory for Infrared Astronomy; Space Infrared Telescope Facility; Submillimeter Intermediate Mission; Large Deployable Reflector; Submillimeter Interferometer; and Next Generation Orbiting Very Long Baseline Interferometer.

Swanson, Paul N.↗