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Wood, Charles

Publications and source records attributed to Wood, Charles.

At least 19 records

NASA Virtual Conferences and Instruction Over the Internet

Distance learning is not new. Since the time that radio has embellished our culture distance learning has taken on may forms. With the onset of television, video tape and satellite link ups the world of multimedia has taken a presence in our remote learning environment. Now in the information age new models for bring the best education to people through out the world is in its early stages. Recent "Information Age" technological developments have made key advancements to distance learning through the greater bandwidths now available over the Internet and a broader communications infrastructure that extends to classrooms throughout the country and the world. Further, new software compression technology allows audio and video to be communicated over the Internet much more efficiently. Larger amounts of data can be transferred to remote sites at less cost. The purpose of this paper is to demonstrate the use of state-of-art technology in the educational community. The focus will be on virtual conferences, virtual instruction and remote education. The techniques herein have been developed by NASA and the University of North Dakota(UND) through the use of existing software and hardware purchased in the United States. NASA has awarded UND a grant for continued research in this area based on their pioneering effort to date. NASA has been conducting "Virtual Conferences" from Ames Research Center in order to make unique educational opportunities available to participants across the country and internationally. Through the use of this technical approach, hundreds of teachers have been able to attend events where physical or financial barriers traditionally prevented their attendance. This technique is currently being adopted by industry due to its scaleable merit.

Leon, Mark

Apparatus Measures Seebeck Coefficient And Resistivity

Electrical measurements made by four point probes, two of which double as temperature probes. Laboratory apparatus measures both Seebeck coefficients and electrical resistivities of candidate thermoelectric materials at temperatures from ambient to 1,300 K. Apparatus makes possible to take both measurements alternately and in rapid succession during same heating cycle, thereby reducing distortion.

Zoltan, Leslie D.

Advanced materials for high-temperature thermoelectric energy conversion

A number of refractory semiconductors are under study at the Jet Propulsion Laboratory for application in thermal to electric energy conversion for space power. The main thrust of the program is to improve or develop materials of high figure of merit and, therefore, high conversion efficiencies over a broad temperature range. Materials currently under investigation are represented by silicon-germanium alloys, lanthanum telluride, and boron carbide. The thermoelectric properties of each of these materials, and prospects for their further improvements, are discussed. Continued progress in thermoelectric materials technology can be expected to yield reliable space power systems with double to triple the efficiency of current state of the art systems.

Vining, Cronin B.

Placement Of O-Rings In Solid Rocket Booster

Brief report proposes to modify placement of O-ring seals in joints of Solid Rocket Booster of Space Shuttle. Modified joint and seal essentially "inside-out" version of old joint and seal. O-rings placed between outer side of tang and clevis. Joint rotation pushes tang harder against O-rings, thereby making even tighter seal. Proposal derived from analysis of Space Shuttle Challenger disaster, attributed to failure of these O-ring seals.

Wood, Charles

Advanced NSTS propulsion system verification study

The merits of propulsion system development testing are discussed. The existing data base of technical reports and specialists is utilized in this investigation. The study encompassed a review of all available test reports of propulsion system development testing for the Saturn stages, the Titan stages, and the Space Shuttle main propulsion system. The knowledge on propulsion system development and system testing available from specialists and managers was also 'tapped' for inclusion.

Wood, Charles

Annealing group III-V compound doped silicon-germanium alloy for improved thermo-electric conversion efficiency

The thermoelectric conversion efficiency of a GaP doped SiGe alloy is improved about 30 percent by annealing the alloy at a temperature above the melting point of the alloy, preferably stepwise from 1200 C to 1275 C in air to form large grains having a size over 50 microns and to form a GeGaP rich phase and a silicon rich phase containing SiP and SiO2 particles.

Vandersande, Jan W.

Research In Thermoelectric Materials

Report reviews current research in thermoelectric materials with view towards development of materials of greater energy-conversion efficiency. Emphasis on effort to understand and manipulate microstructure to increase thermoelectric figure of merit, Z. Thermoelectric properties of three broad categories of materials discussed. First category includes alloys of group IV elements like silicon and germanium. Second category is rare-earth chalcogenides. Third category includes narrow-band semiconductors, especially boron carbides.

Wood, Charles

Thermal Brushes For Memory-Metal Actuators

Thermoelectric elements with wire-brush contacts remove heat from or add heat to memory-metal actuators and thereby enable them to respond faster than previously possible. Memory-metal actuator formed to shape while hot, then to another shape while cold. When cold actuator heated so temperature rises above critical point, snaps from cold shape to hot shape. Upon cooling, actuator returns to cold shape, ready for another cycle. Clearly, faster actuator is heated and cooled, the faster it operates.

Wood, Charles

Computerized Analysis Of Thermal-Diffusivity Data

Improved data-acquisition and data-analysis system for thermal-diffusivity measurements using flash method incorporates digital oscilloscope and microcomputer for rapid reduction of experimental data. In thermal-diffusivity apparatus thin specimen heated on one face by pulsed xenon flashlamp, subsequent temperature rise on opposite face monitored by infrared detector. Thermal diffusivity estimated from thickness of specimen and from time after initial pulse during which temperature rise reaches half maximum value. Accuracy of estimate improved by correcting temperature measurements for radiative loss of heat from specimen and for finite duration and specific waveform of flashlamp pulse. System devised for use in high-temperature measurements of thermoelectric materials.

Chmielewski, Artur B.

Thermocouple for heating and cooling of memory metal actuators

A semiconductor thermocouple unit is provided for heating and cooling memory metal actuators. The semiconductor thermocouple unit is mounted adjacent to a memory metal actuator and has a heat sink attached to it. A flexible thermally conductive element extends between the semiconductor thermocouple and the actuator and serves as a heat transfer medium during heating and cooling operations.

Wood, Charles

Program Collects And Analyzes Thermoelectric Data

Large gradient seebeck coefficient measurement computer program gathers many channels of data, performs analysis, and plots each set of data simutaneously. User can modify code to alter number of channels of data collected and sampling rate and equations that process data. Written in HP Basic. Program also adaptable to other types of data.

Chmielewski, Art B.

Boron Carbides As Thermo-electric Materials

Report reviews recent theoretical and experimental research on thermoelectric materials. Recent work with narrow-band semiconductors demonstrated possibility of relatively high thermoelectric energy-conversion efficiencies in materials withstanding high temperatures needed to attain such efficiencies. Among promising semiconductors are boron-rich borides, especially boron carbides.

Wood, Charles

Improved GaP doped SiGe thermoelectric material

Work at TECO has independently confirmed the early results obtained at JPL that high-temperature heat-treatment of SiGe/GaP alloys can significantly increase the figure of merit Z of these alloys. Several possible reasons for this improvement are given. Experiments are in progress to test these various hypothesis.

Vandersande, Jan W.

Advances In Thermoelectric Materials

Rare-earth chalcogenides and boron-rich borides show promise. Report discusses search for materials performing more efficiently in high-temperature thermoelectric conversion. Begins with summary of developments during past three decades. Followed by brief introduction to theory of thermoelectric energy conversion, then by experimental findings and by some additional theory on specific materials.

Wood, Charles

Measuring Specific Heats at High Temperatures

Flash apparatus for measuring thermal diffusivities at temperatures from 300 to 1,000 degrees C modified; measures specific heats of samples to accuracy of 4 to 5 percent. Specific heat and thermal diffusivity of sample measured. Xenon flash emits pulse of radiation, absorbed by sputtered graphite coating on sample. Sample temperature measured with thermocouple, and temperature rise due to pulse measured by InSb detector.

Vandersande, Jan W.

Electron-Spin Resonance in Boron Carbide

Samples exhibit Curie-law behavior in temperature range of 2 to 100 K. Technical paper presents studies of electron-spin resonance of samples of hot pressed B9 C, B15 C2, B13 C2, and B4 C. Boron carbide ceramics are refractory solids with high melting temperatures, low thermal conductives, and extreme hardnesses. They show promise as semiconductors at high temperatures and have unusually large figures of merit for use in thermoelectric generators.

Wood, Charles

Development of improved p-type silicon-germanium alloys

Annealing experiments in the temperature range 1100-1275 C have been performed on p-type Si(0.8)Ge(0.2) samples with BP, B(6.5)P, and GaSb material additives. Both electrical resistivity and Seebeck coefficient generally decrease for these samples as annealing temperature is increased, with thermoelectric power factor sometimes being improved by annealing.

Mclane, George