Tech Briefs

Robotic End Effectors for Hard-Rock Climbing

End effectors emulate equipment used by human climbers.Pasadena, California Special-purpose robot hands (end effectors) now under development are intended to enable robots to traverse cliffs much as human climbers do. Potential applications for robots having this capability include scientific exploration (both on Earth and other rocky bodies in space), military reconnaissance, and outdoor search and rescue operations.

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FEA Software Enables Study of Tissue Ablation Dynamics

An improved ablation device model uses a feedback loop to account for varying properties of heated or damaged tissue. Regulatory agencies such as the US FDA must examine new medical devices to ensure that they are safe and effective. Sometimes, devices work successfully despite the fact that the mechanism of how they work isn't fully understood. In these cases, the FDA performs basic research to fill in these knowledge gaps.

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Time-Transfer System for Two Orbiting Spacecraft

A report describes the time-transfer system of the Gravity Recovery and Climate Experiment (GRACE), in which information on the distribution of Earth mass is extracted from position and time measurements for two spacecraft about 200 km apart in a circular, nearly polar orbit. Each spacecraft carriers a Global Positioning System (GPS) receiver, a K/Ka-band ranging (KBR) instrument, and an ultra-stable oscillator (USO) that serves as a clock for the GPS and KBR units.

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Calculating Mass Diffusion in High-Pressure Binary Fluids

This model could contribute to understanding of high-pressure combustion. A comprehensive mathematical model of mass diffusion has been developed for binary fluids at high pressures, including critical and supercritical pressures. Heretofore, diverse expressions, valid for limited parameter ranges, have been used to correlate high-pressure binary mass- diffusion- coefficient data. This model will likely be especially useful in the computational simulation and analysis of combustion phenomena in diesel engines, gas turbines, and liquid rocket engines, wherein mass diffusion at high pressure plays a major role.

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Current Pulses Momentarily Enhance Thermoelectric Cooling

Transient cooling could be attractive for some semiconductor devices. The rates of cooling afforded by thermoelectric (Peltier) devices can be increased for short times by applying pulses of electric current greater than the currents that yield maximum steady-state cooling. It has been proposed to utilize such momentary enhancements of cooling in applications in which diode lasers and other semiconductor devices are required to operate for times of the order of milliseconds at temperatures too low to be easily obtainable in the steady state. In a typical contemplated application, a semiconductor device would be in contact with the final (coldest) somewhat taller stage of a multistage thermoelectric cooler. Steady current would be applied to the stages to produce steady cooling. Pulsed current would then be applied, enhancing the cooling of the top stage momentarily.

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Improved Cryostat for Cooling a Wide Panel

Less technician time and lower consumption of helium translate to lower cost.An improved cryostat has been developed for cooling a wide panel evenly over its surface to a temperature of -423 °F (-253 °C) by use of liquid helium. Originally, the cryostat was to be used in measuring apparent strains in wide aluminum/ lithium panels as functions of temperature in order to develop data for temperature compensation of the readings of strain gauges on a tank containing liquid hydrogen. Relative to the cryostat used previously for this purpose, the improved cryostat can be prepared for a test in less time, and it loses less helium during each test.

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Making the Monte Carlo Approach Easier and Faster

Libraries of random number generators can make implementing Monte Carlo simulations easier. Originally introduced by Nicholas Metropolis during the Manhattan Project, Monte Carlo methods today have very broad and extensive use in various areas of science and technology. Random number generators (RNGs) are a core part of any Monte Carlo method, having a significant impact on the overall quality and performance of Monte Carlo simulations. Libraries of RNGs can make implementing Monte Carlo simulations much easier and faster. The most important role of high-performance libraries is to provide facilities that can make writing programs simpler, substantially speed up development, and improve program efficiency in terms of performance.

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