Tech Briefs

Software for Displaying High-Frequency Test Data

An easy-to-use, intuitive computer program was written to satisfy a need of test operators and data requestors to quickly view and manipulate high-frequency test data recorded at the East and West Test Areas at Marshall Space Flight Center. By enabling rapid analysis, this program makes it possible to reduce times between test runs, thereby potentially reducing the overall cost of test operations. The program can be used to perform quick frequency analysis, using multiple fast- Fourier-transform windowing and amplitude options. The program can generate amplitude-versus-time plots with full zoom capabilities, frequency-component plots at specified time intervals, and waterfall plots (plots of spectral intensity versus frequency at successive small time intervals, showing the changing frequency components over time). There are options for printing of the plots and saving plot data as text files that can be imported into other application programs. The program can perform all of the aforementioned plotting and plot-data-handling functions on a relatively inexpensive computer; other software that performs the same functions requires computers with large amounts of power and memory.

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Software To Secure Distributed Propulsion Simulations

CORBASec brings role-based security to CORBA-object-wrapped simulations. Distributed-object computing systems are presented with many security threats, including network eavesdropping, message tampering, and communications middleware masquerading. NASA Glenn Research Center, and its industry partners, has taken an active role in mitigating the security threats associated with developing and operating their proprietary aerospace propulsion simulations. In particular, they are developing a collaborative Common Object Request Broker Architecture (CORBA) Security (CORBASec) test bed to secure their distributed aerospace propulsion simulations. Glenn has been working with its aerospace propulsion industry partners to deploy the Numerical Propulsion System Simulation (NPSS) object-based technology. NPSS is a program focused on reducing the cost and time in developing aerospace propulsion engines.

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Next-Generation Car Engines Optimized to Improve Gas Mileage

This paper examines the simulation and thermal optimization of a wide-range oxygen sensor, which helps to regulate clean and efficient motor operation. The setup of the finite element model of the oxygen sensor is discussed in detail, along with how the sensor’s geometry and material properties were optimized for thermal loads that represented worst-case operating conditions. Developed by Delphi Corporation, a provider of mobile electronics and transportation components, the completed sensor design currently is being integrated into the next generation of car engines to increase fuel efficiency and reduce environmentally unfriendly exhaust emissions. Engines featuring these sensors are expected to be used in 2004.

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Improved Collision-Detection Method for Robotic Manipulator

Collisions are detected in a computationally efficient manner. An improved method has been devised for the computational prediction of a collision between (1) a robotic manipulator and (2) another part of the robot or an external object in the vicinity of the robot. The method is intended to be used to test commanded manipulator trajectories in advance so that execution of the commands can be stopped before damage is done. The method involves utilization of both (1) mathematical models of the robot and its environment constructed manually prior to operation and (2) similar models constructed automatically from sensory data acquired during operation. The representation of objects in this method is simpler and more efficient(with respect to both computation time and computer memory), relative to the representations used in most prior methods.

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Small, Untethered, Mobile Robots for Inspecting Gas Pipes

These robots would be powered by gas flows. Small, untethered mobile robots denoted gas-pipe explorers (GPEXs) have been proposed for inspecting the interiors of pipes used in the local distribution natural gas. The United States has network of gas- distribution pipes with a total length of approximately 109 m. These pipes are often made of iron and steel and some are more than 100 years old. As this network ages, there is a need to locate weaknesses that necessitate repair and/or preventive maintenance. The most common weaknesses are leaks and reductions in thickness, which are caused mostly by chemical reactions between the iron in the pipes and various substances in soil and groundwater.

Posted in: Machinery & Automation, Briefs, TSP

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MEMS-Based Piezoelectric/Electrostatic Inchworm Actuator

Nanometer steps could be concatenated into overall travel of hundreds of microns. A proposed inchworm actuator, to be designed and fabricated according to the principles of microelectromechanical systems (MEMS), would effect linear motion characterized by steps as small as nanometers and an overall range of travel of hundreds of microns. Potential applications for actuators like this one include precise positioning of optical components and active suppression of noise and vibration in scientific instruments, conveyance of wafers in the semiconductor industry, precise positioning for machine tools, and positioning and actuation of microsurgical instruments.

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Combining Multiple Gyroscope Outputs for Increased Accuracy

A lightweight, low-power, compact MEMS gyroscope array could perform comparably to a larger more-conventional gyroscope. A proposed method of processing the outputs of multiple gyroscopes to increase the accuracy of rate (that is, angular- velocity) readings has been developed theoretically and demonstrated by computer simulation. Although the method is applicable, in principle, to any gyroscopes, it is intended especially for application to gyroscopes that are parts of microelectromechanical systems (MEMS). The method is based on the concept that the collective performance of multiple, relatively inexpensive, nominally identical devices can be better than that of one of the devices considered by itself. The method would make it possible to synthesize the readings of a single, more accurate gyroscope (a “virtual gyroscope”) from the outputs of a large number of microscopic gyroscopes fabricated together on a single MEMS chip. The big advantage would be that the combination of the MEMS gyroscope array and the processing circuitry needed to implement the method would be smaller, lighter in weight, and less power-hungry, relative to a conventional gyroscope of equal accuracy.

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