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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

High efficiency, long life traveling wave tubes for future communications satellites

Electron beam devices, primarily traveling wave tubes (TWTs), have been used as the power amplifiers in almost all space communications and data transmission systems. Based on the technology that is presently available and the expected success of current research efforts, it is reasonable to predict the development of a new class of microwave TWTs with efficiencies in excess of 60 percent and lifetimes of at least 10 years. Because of this rapid advance of technology, the TWT is expected to remain the dominant device for power amplifiers in space.

Dayton, James A., Jr.↗
NASA NTRS1988

High efficiency, long life traveling wave tubes for future communications satellites

Electron beam devices, primarily traveling wave tubes (TWTs), have been used as the power amplifiers in almost all space communications and data transmission systems. Based on the technology that is presently available and the expected success of current research efforts, it is reasonable to predict the development of a new class of microwave TWTs with efficiencies in excess of 60 percent and lifetimes of at least ten years. Because of this rapid advance of technology, the TWT is expected to remain the dominant device for power amplifiers in space.

Dayton, J. A., Jr.↗
NASA NTRS1996

Interface Circuit For Connecting Instruments To Computers

Circuit card designed to act as interface between K-bus remote terminal. Enables digital communication between electronic instrumentation designed to communicate with other equipment via K-bus and control and telemetry-monitoring computer designed to communicate with other equipment via MIL-STD-1553B (or MIL-STD-1773) bus. Provides K-bus interface for as many as four instrumentation circuit cards.

Katz, Richard B.↗
NASA NTRS2014

Circuit for Communication over DC Power Line Using High Temperature Electronics

A high temperature communications circuit includes a power conductor for concurrently conducting electrical energy for powering circuit components and transmitting a modulated data signal, and a demodulator for demodulating the data signal and generating a serial bit stream based on the data signal. The demodulator includes an absolute value amplifier for conditionally inverting or conditionally passing a signal applied to the absolute value amplifier. The absolute value amplifier utilizes no diodes to control the conditional inversion or passing of the signal applied to the absolute value amplifier.

Krasowski, Michael J.↗
NASA NTRS1994

Integration and test of high-speed transmitter electronics for free-space laser communications

The NASA Lewis Research Center in Cleveland, Ohio, has developed the electronics for a free-space, direct-detection laser communications system demonstration. Under the High-Speed Laser Integrated Terminal Electronics (Hi-LITE) Project, NASA Lewis has built a prototype full-duplex, dual-channel electronics transmitter and receiver operating at 325 megabit S per second (Mbps) per channel and using quaternary pulse-position modulation (QPPM). This paper describes the integration and testing of the transmitter portion for future application in free-space, direct-detection laser communications. A companion paper reviews the receiver portion of the prototype electronics. Minor modifications to the transmitter were made since the initial report on the entire system, and this paper addresses them. The digital electronics are implemented in gallium arsenide integrated circuits mounted on prototype boards. The fabrication and implementation issues related to these high-speed devices are discussed. The transmitter's test results are documented, and its functionality is verified by exercising all modes of operation. Various testing issues pertaining to high-speed circuits are addressed. A description of the transmitter electronics packaging concludes the paper.

Soni, Nitin J.↗
NASA NTRS2004

Phytoplankton-Fluorescence-Lifetime Vertical Profiler

A battery-operated optoelectronic instrument is designed to be lowered into the ocean to measure the intensity and lifetime of fluorescence of chlorophyll A in marine phytoplankton as a function of depth from 0 to 300 m. Fluorescence lifetimes are especially useful as robust measures of photosynthetic productivity of phytoplankton and of physical and chemical mechanisms that affect photosynthesis. The knowledge of photosynthesis in phytoplankton gained by use of this and related instruments is expected to contribute to understanding of global processes that control the time-varying fluxes of carbon and associated biogenic elements in the ocean. The concentration of chlorophyll in the ocean presents a major detection challenge because in order to obtain accurate values of photosynthetic parameters, the intensity of light used to excite fluorescence must be kept very low so as not to disturb the photosynthetic system. Several innovations in fluorometric instrumentation were made in order to make it possible to reach the required low detection limit. These innovations include a highly efficient optical assembly with an integrated flow-through sample interface, and a high-gain, low-noise electronic detection subsystem. The instrument also incorporates means for self-calibration during operation, and electronic hardware and software for control, acquisition and analysis of data, and communications. The electronic circuitry is highly miniaturized and designed to minimize power demand. The instrument is housed in a package that can withstand the water pressure at the maximum depth of 300 m. A light-emitting diode excites fluorescence in the sample flow cell, which is placed at one focal point of an ellipsoidal reflector. A photomultiplier tube is placed at the other focal point. This optical arrangement enables highly efficient collection of fluorescence emitted over all polar directions. Fluorescence lifetime is measured indirectly, by use of a technique based on the same principle as the one described in "Fluorometer for Analysis of Photosynthesis in Phytoplankton" (SSC-00110), NASA Tech Briefs, Vol. 24, No. 1 (November 2000), page 79. The excitation is modulated at a frequency of 70 MHz, and the phase shift between the excitation light and the emitted fluorescence is measured by a detection method in which the 70 MHz signal is down-converted to a 400 Hz signal. The fluorescence lifetime can be computed from the known relationship among the fluorescence lifetime, phase shift, and modulation frequency

Fernandez, Salvador M.↗
NASA NTRS2007

Two-Way Communication Using RFID Equipment and Techniques

Equipment and techniques used in radio-frequency identification (RFID) would be extended, according to a proposal, to enable short-range, two-way communication between electronic products and host computers. In one example of a typical contemplated application, the purpose of the short-range radio communication would be to transfer image data from a user s digital still or video camera to the user s computer for recording and/or processing. The concept is also applicable to consumer electronic products other than digital cameras (for example, cellular telephones, portable computers, or motion sensors in alarm systems), and to a variety of industrial and scientific sensors and other devices that generate data. Until now, RFID has been used to exchange small amounts of mostly static information for identifying and tracking assets. Information pertaining to an asset (typically, an object in inventory to be tracked) is contained in miniature electronic circuitry in an RFID tag attached to the object. Conventional RFID equipment and techniques enable a host computer to read data from and, in some cases, to write data to, RFID tags, but they do not enable such additional functions as sending commands to, or retrieving possibly large quantities of dynamic data from, RFID-tagged devices. The proposal would enable such additional functions. The figure schematically depicts an implementation of the proposal for a sensory device (e.g., a digital camera) that includes circuitry that converts sensory information to digital data. In addition to the basic sensory device, there would be a controller and a memory that would store the sensor data and/or data from the controller. The device would also be equipped with a conventional RFID chipset and antenna, which would communicate with a host computer via an RFID reader. The controller would function partly as a communication interface, implementing two-way communication protocols at all levels (including RFID if needed) between the sensory device and the memory and between the host computer and the memory. The controller would perform power V

Jedry, Thomas↗
NASA NTRS1996

Telemammography Using Satellite Communications

Telemammography, the electronic transmission of digitized mammograms, can connect patients with timely, critical medical expertise; howev er, an adequate terrestrial communications infrastructure does not exist in these areas. NASA Lewis Research Center's Advanced Space Commu nications Laboratory is now working with leading breast cancer resear ch hospitals, including the Cleveland Clinic and the University of Virginia, to perform the critical research necessary to allow new satell ite networks to support telemammography.

Source record↗
NASA NTRS1995

NASA wide electronic publishing system: Electronic printing and duplicating. Stage 3 evaluation report

The report is presented in four sections: The Introduction describes the duplicating configuration under evaluation and the Background contains a chronological description of the evaluation segmented by phases 1 and 2. This section includes the evaluation schedule, printing and duplicating requirements, storage and communication requirements, electronic publishing system configuration, existing processes and proposed processes, billing rates, costs and productivity analysis, and the return on investment based upon the data gathered to date. The third section contains the phase 1 comparative cost and productivity analysis. This analysis demonstrated that LaRC should proceed with a 90-day evaluation of the DocuTech and follow with a phase 2 cycle to actually demonstrate that the proposed system would meet the needs of LaRC's printing and duplicating requirements, benchmark results, cost comparisons, benchmark observations, and recommendations. These are documented after the recommendations.

Tuey, Richard C.↗
NASA NTRSDate not supplied

A Brief Overview of Silicon Carbide Based Smart Sensor System Technologies for Planetary and Aeronautics Applications

A range of aerospace application related to planetary exploration and aeronautic engine operations require Smart Sensor System technologies operational in harsh environments. A Smart Sensor System as described here implies the use of sensors combined with electronics and other supporting technologies. For example, missions to the surface of planets like Venus or Mercury are challenged by extreme temperatures and environments, e.g., extended Venus operation 465°C [1]. In response, NASA has been developing capabilities for a small lander that is designed to operate for months in the extreme temperatures. These capabilities span electronics, sensors, communications, and power. Such a lander would enable new revolutionary science. Similar game changing capabilities are enabled by the introduction of high temperature smart systems into aeronautic engine applications to enable distributed intelligence within the engine system [2]. Core to meeting these applications is operational harsh environment electronics, corresponding sensor systems, and their integration. This presentation concentrates on the status of Smart System technologies emphasizing the role of Silicon Carbide (SiC) electronics and sensors. For example, SiC integrated circuit (IC) electronics have matured to a state where a simple long-life scientific probe is feasible for extended Venus surface operations [1, 3]. Maturation of these high temperature electronics and other technologies has been part of NASA projects to provide an operational system for in situ exploration of the Venus surface for up to 60 days [1,3-4]. This is in parallel to work expanding the capabilities of the sensor technology to provide science measurements on the Venus surface. This technology development, as well as that for other planetary applications and intelligent high temperature engine operations, will be discussed.

engine monitoring↗
NASA NTRS2012

A Brief Review of the Need for Robust Smart Wireless Sensor Systems for Future Propulsion Systems, Distributed Engine Controls, and Propulsion Health Management

Smart Sensor Systems with wireless capability operational in high temperature, harsh environments are a significant component in enabling future propulsion systems to meet a range of increasingly demanding requirements. These propulsion systems must incorporate technology that will monitor engine component conditions, analyze the incoming data, and modify operating parameters to optimize propulsion system operations. This paper discusses the motivation towards the development of high temperature, smart wireless sensor systems that include sensors, electronics, wireless communication, and power. The challenges associated with the use of traditional wired sensor systems will be reviewed and potential advantages of Smart Sensor Systems will be discussed. A brief review of potential applications for wireless smart sensor networks and their potential impact on propulsion system operation, with emphasis on Distributed Engine Control and Propulsion Health Management, will be given. A specific example related to the development of high temperature Smart Sensor Systems based on silicon carbide electronics will be discussed. It is concluded that the development of a range of robust smart wireless sensor systems are a foundation for future development of intelligent propulsion systems with enhanced capabilities.

Hunter, Gary W.↗