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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Application of ERTS-1 and multiplexed SLAR imagery for the study of flooded shorelines

The major purpose of this study is to determine the accuracy of visual interpretations of data from two different sensors (ERTS-1; ERIM's multiplexed SLAR) for the study of flooded shorelines. Uncomplicated and primarily visual interpretation techniques are employed. These methods are considered most readily available to officials of local and small regional organizations who may need rapid reconnaissance mapping and information for the organization of disaster relief. Assumptions concerning the timely receipt of such remotely sensed data by those directing the relief have been made. Generally, it is determined that ERTS-1 and SLAR data are complementary, especially with respect to the interpretation of urban or built-up areas which are flooded, and together they can provide the necessary information for guiding relief operations.

Bryan, M. L.↗
NASA NTRS1977

Development of a multiplexed bypass control system for aerospace batteries

A breadboard bypass control system was developed to control a battery comprised of 26 JPL-developed negative limited Ni-Cd cells. The system was designed to automatically remove cells from the circuit when their voltages exceeded a fixed limit on charge and fell below a fixed limit on discharge. Major components of the system consisted of a cell voltage monitor, a multiplexing circuit, and individual electromechanical relays for each cell. The system was found to function well in controlling the battery during a simulated 10-month MM-71 mission and a 2-month simulated low earth orbit cycling mission. A flight version of the bypass system was estimated to have a total parts count of 150 and total weight of 1.63 kg. When fully developed, the system shows promise for improving life and reliability of spacecraft batteries.

Frank, H. A.↗
NASA NTRS1978

Signal-to-noise ratios of multiplexing spectrometers in high backgrounds

Signal-to-noise ratios and the amount of multiplexing gain achieved with a Michelson spectrometer during detector and background noise are studied. Noise caused by the warm background is found in 10 and 20-micron atmospheric windows in high resolution Fourier spectroscopy. An equation is derived for the signal-to-noise ratio based on the number of channels, total time to obtain the complete spectrum, the signal power in one spectral element, and the detector noise equivalent power in the presence of negligible background. Similar expressions are derived for backgrounds yielding a noise equivalent power to a spectral element, and backgrounds having flat spectra in the frequency range under investigation.

Knacke, R. F.↗
NASA NTRS1978

Orbiter multiplexer-demultiplexer (MDM)/Space Lab Bus Interface Unit (SL/BIU) serial data interface evaluation, volume 2

Tests were performed to evaluate the operating characteristics of the interface between the Space Lab Bus Interface Unit (SL/BIU) and the Orbiter Multiplexer-Demultiplexer (MDM) serial data input-output (SIO) module. This volume contains the test equipment preparation procedures and a detailed description of the Nova/Input Output Processor Simulator (IOPS) software used during the data transfer tests to determine word error rates (WER).

Tobey, G. L.↗
NASA NTRS1980

Digital multiplexing of analog data in a microprocessor controlled data acquisition system

The purpose of the paper is to explore the ramifications of doing the multiplexing function in the digital domain and of using the microprocessor to replace the hardwired control logic which resides in the typical analog to digital converter. Two types of conversion (one working in parallel inputs, and one in sequential order) strategies are discussed where the microprocessor is in full control of the conversion. One advantage of using a digital multiplexor is that, contrary to an analog multiplexor, it does not degrade the fidelity of the conversion process.

Cliff, R. A.↗
NASA NTRS1982

Queueing analysis of synchronous time division multiplexing with individual source buffering

Synchronous time division multiplexing is analyzed. Packets of information arrive at the system as a compound Poisson process, and are transmitted only during individual periodic intervals. Packet arrivals are blocked (lost) if the system has a finite capacity and is congested. Using the theory of semiregenerative processes, the distribution of the number of packets in the system (system size) is found. This nonstationary distribution is used to determine the complete system behavior, including the delay distributions, the blocking probability, and the density of the system size at arrival instants. Numerical examples illustrate applications of the results given.

Clare, L.↗
NASA NTRS1982

Multiplexed extrinsic silicon detector array

Multiplexed extrinsic silicon detector arrays for infrared applications were developed and tested. Cryogenic electronics are discussed. Ambient temperature electronics are also discussed.

Yee, J. F.↗
NASA NTRS1981

NASA Communications Division (NASCOM) Tracking and Data Relay Satellite System (TDRSS) shuttle multiplexer-demultiplexer data system (MDM) and supporting items

The multiplexer-demultiplexer (MDM) project included the design, documentation, manufacture, and testing of three MDM Data Systems. The equipment is contained in 59 racks, and includes more than 3,000 circuit boards and 600 microprocessors. Spares, circuit card testers, a master set of programmable integrated circuits, and a program development system were included as deliverables. All three MDM's were installed, and were operationally tested. The systems performed well with no major problems. The progress and problems analysis, addresses schedule conformance, new technology, items awaiting government approval, and project conclusions are summarized. All contract modifications are described.

New, S. R.↗
NASA NTRS1981

An integrated control panel utilizing a programmable varistor-multiplexed dichroic liquid crystal display

Due to the conflicting demands of modern aircraft for increased systems/sensors and the decrease in cockpit panel size, weight, volume, and power, conventional discrete/dedicated methods of display and control are fast becoming obsolete. A means is sought to integrate the control and display into multifunctional programmable devices, thus giving the ability to increase system functions and yet conserve panel space. A potential solution to the control portion of the problem has come to be known as the Integrated Control Panel (ICP) approach. Flat panel display technology and controls using programmable flat panel displays with transparent capacitive touch control overlays offer the largest potential advantages. The flat panel display made of varistor-multiplexed dichroic liquid crystal (LCD) developed by GE in recent years appears to offer the ideal monochrome solution.

Whitton, I. J.↗
NASA NTRS1983

Microcomputer Multiplexes Alphanumeric Labels on CRT's

External, low-power alphanumeric label generator eliminates costly video circuitry. Microprocessor-based system for multiplexing alphanumeric and analog data stores both program and data. Uses inexpensive circuits, consumes minimal current, is programmable by user, adapts to many CRT monitors. System generates 5-by-7 dot-matrix characters. System speed is adaquate for medical monitoring purposes.

Cooper, T.↗
NASA NTRS1982

Thematic mapper protoflight model preshipment review data package. Volume 4: Appendix. Part A: Multiplexer data book 2

Final performance test data for the thematic mapper flight model multiplexer are presented in tables. Aspects covered include A/D thresholds for bands 5, 6, and 7; cross talk; the thermistor; bilevel commands signal parameters; A/D threshold ambient, voltage margin low bus; serial data and bit clock parameters; and the wire check. Tests were conducted at ambient temperature.

Source record↗
NASA NTRS1983

On the design of prioritized multiplexing systems

Systems in which many data sources are multiplexed over a single communication channel are considered. Data from all the sources are generated in fixed-length packets, and are stored in a common buffer with finite capacity. Packets overflowed or removed from the buffer prior to transmission are lost. The system performance measure is the set of packet loss probabilities associated with the sources. Queueing disciplines vary depending on the stringency of prioritization and the utilization of system resources. The set of all possible performances is characterized as the set of all queueing disciplines is spanned. Whether a given performance is possible can be deduced. Strategies that achieve the minimum overall loss probability are identified. The extreme disciplines are specified, and their performances are calculable by means of a given algorithm.

Clare, L. P.↗
NASA NTRS1984

Fiber optic data bus using Frequency Division Multiplexing (FDM) and an asymmetric coupler

A fiber optic data bus, using frequency division multiplexing (FDM) is discussed. The use of FDM is motivated by the need to avoid central control of the bus operation. A major difficulty of such a data bus is introduced by the couplers. An efficient low loss access coupler with an asymmetric structure is presented, and manufacturing processes for the coupler are proposed.

Zanger, M.↗
NASA NTRS1984

Large-memory real-time multichannel multiplexed pattern recognition

The principle and experimental design of a real-time multichannel multiplexed optical pattern recognition system via use of a 25-focus dichromated gelatin holographic lens (hololens) are described. Each of the 25 foci of the hololens may have a storage and matched filtering capability approaching that of a single-lens correlator. If the space-bandwidth product of an input image is limited, as is true in most practical cases, the 25-focus hololens system has 25 times the capability of a single lens. Experimental results have shown that the interfilter noise is not serious. The system has already demonstrated the storage and recognition of over 70 matched filters - which is a larger capacity than any optical pattern recognition system reported to date.

Gregory, D. A.↗
NASA NTRS1983

Wavelength division multiplexing for future Space Station data systems

A future Space Station will require information network architectures and technologies that are evolvable, adaptive, high performing, and self-correcting and repairing. One of the conceptual network configurations involves fiber optic data buses with Wavelength Division Multiplexing (WDM). Discussion of this network concept, components being developed and results on a four-channel WDM star bus will be presented.

Hendricks, H. D.↗