Bendix Field Engineering Corporation (United States)

Documentation has been called the lifeline of computer systems. This is especially true for the Mission Operations Division (MOD) at the NASA Goddard Space Flight Center, where the high visibility of spacecraft missions requires quick and accurate resolution of computer problems. To develop documentation to support this environment, the MOD has devised a documentation structure and tailoring scheme that is flexible but not flimsy, ordered but not rigid, and focused without being limited. This paper describes the essential elements of this structure.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The authors report on magnetic properties and voltage hold-off strengths for various insulation materials used with iron-based metallic glass alloys with both low and high induced anisotropy energies. Cowound insulation films as well as conformal insulations were investigated. None of the insulations was found to have uniformly good voltage hold-off, low induced stress, and a high packing fraction for pulse power applications. Conformal insulations either tended to degrade the magnetic properties of the cores or were too thin to provide uniform voltage hold-off. Cowound insulations had adequate voltage hold-off but resulted in cores with lower packing fractions than did conformal insulations. Cores cowound with mica paper insulation and annealed after winding had the best magnetic properties among the cowound cores. >

A theory of solid-state fusion based on the formation of a D+ Bose Bloch condensate (BBC) is summarized. The first step toward fusion is a coalescence reaction that converts a multiple-occupation s...

Lattice-matched InAlAs/n-InP and InAlAs/n/sup +/-InP heterostructure MESFETs with extrinsic transconductances of 220 and 155 mS/mm, respectively, have been fabricated on semi-insulating InP substrates. Maximum stable gains of 11.5 dB for the 1.25- mu m-gate n-InP channel and 10 dB for the 1.0- mu m-gate n/sup +/-InP channel devices were measured at 10 GHz. An extrapolated f/sub max/ of 42 GHz was obtained for the n/sup +/-channel MESFET. >

Resonant tunnelling diodes consisting of an MBE-grown AlInAs barrier on each side of a lattice-matched GaInAs well have been fabricated. Current peak/valley ratios up to 7.1 and 39 have been measured at 300 K and 77K, respectively. These represent the largest values reported to date in any double-barrier, single-well device. The enhanced peak/valley ratio has been attributed to thick barriers (72 Å) and wide, undoped GaInAs spacer layers (400 Å).

Torque associated with rotor stall is shown to be an important factor in the yaw behaviour of fixed pitch horizontal axis wind turbines (HAWT). For a given operating machine, the best performance occurs when the plane of rotation is perpendicular to the wind velocity for all wind speeds, V, less than a fixed value, V0. For V > V0 a velocity dependent torque yaws a free rotor to more efficient energy gathering positions provided the yaw torque exceeds the corresponding machine frictional torque. The optimum angular positions (yaw trajectories) computed from dynamic equilibrium considerations are compared with, and shown to be in satisfactory agreement with, solutions furnished by a model based on a postulated energy gathering function. The postulational approach developed is particularly useful because of its generality and simplicity in describing the performance of a HAWT. It is noted that although it is advantageous from a performance point of view to yaw the rotor to the optimum position corresponding to a given wind velocity established by either dynamic equilibrium or the energy gathering model, one must be aware of the accompanying increase in cyclic loading. On the other hand, maintaining the plane of rotation perpendicular to the wind velocity at all times could result in significant performance losses as well as fatigue problems in fixed pitch rotors, especially during stall conditions.

A furnace for annealing ion implantation damage in III-V semiconductors has been built and tested. Designed for research applications, the furnace can accommodate odd shapes of material up to 2 in. in diameter. Samples are loaded onto a novel cantilevered support and are not moved during the annealing operation, facilitating proximity annealing techniques. Both chambers of this dual chambered system are O-ring sealed for added safety during annealing in an arsine gas ambient. Electron mobilities between 4400 and 4600 cm2/V s at 300 K are routinely measured for 2×1017 cm−3 gallium arsenide material annealed in this sytem. The system has been used to anneal indium phosphide as well as gallium arsenide wafers.

&lt;div class="htmlview paragraph"&gt;Surface conditioning is one way of reducing the duration and magnitude of the initial transients occurring in friction materials. In developing a laser searing system for semimetallic materials the changes occurring on the surface were characterized as a function of the power density. Excessive power melted the surface of the lining and produced an undesirable microstructure, while too little power did not produce the changes desired. The changes produced by laser searing were found to be similar to the changes produced by other types of surface conditioning.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;The friction and wear performance was studied for linings seared with different power densities. Laser searing primarily increased the low speed, low temperature, pre-burnish friction level. The amount of increase was proportional to the amount of searing. After burnishing the searing did not effect the friction level of the lining. Excessive power densities produced undesirable surface microstructures and persistent rotor scoring.&lt;/div&gt;