Tech Briefs

Finite Element Analysis Used to Examine the Healing of Animal Bones

The effectiveness of using stabilization pins and external skeletal fixators was determined by FEA analysis. When a dog or cat breaks a bone, veterinarians often mend the fracture with a combination of stabilization devices called intra-medullary (IM) pins and external skeletal fixators (ESFs), a technique that is employed daily across the U.S. Research conducted at the University of Georgia under the direction of Dennis Aron, DVM, using ALGOR finite element analysis software, is helping to establish better guidelines for how these stabilization devices can best be used to promote healing of animal fractures.

Posted in: Briefs, Medical

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Model of Mixing Layer With Multicomponent Evaporating Drops

Effects of multiple chemical components are represented with computational efficiency. A mathematical model of a three-dimensional mixing layer laden with evaporating fuel drops composed of many chemical species has been derived. The study is motivated by the fact that typical real petroleum fuels contain hundreds of chemical species. Previously, for the sake of computational efficiency, spray studies were performed using either models based on a single representative species or models based on surrogate fuels of at most 15 species. The present multicomponent model makes it possible to perform more realistic simulations by accounting for hundreds of chemical species in a computationally efficient manner.

Posted in: Briefs, TSP, Physical Sciences

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Role of Meteorology in Flights of a Solar-Powered Airplane

Meteorological support helped ensure safety and success of experimental high-altitude flights. In the summer of 2001, the Helios prototype solar-powered uninhabited aerial vehicle (UAV) [a lightweight, remotely piloted airplane] was deployed to the Pacific Missile Range Facility (PMRF), at Kauai, Hawaii, in an attempt to fly to altitudes above 100,000 ft (30.48 km). The goal of flying a UAV to such high altitudes has been designated a level-I milestone of the NASA Environmental Research Aircraft and Sensor Technology (ERAST) program. In support of this goal, meteorologists from NASA Dryden Flight Research Center were sent to PMRF, as part of the flight crew, to provide current and forecast weather information to the pilots, mission directors, and planners. Information of this kind is needed to optimize flight conditions for peak aircraft performance and to enable avoidance of weather conditions that could adversely affect safety.

Posted in: Briefs, Physical Sciences

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Blade-Pitch Control for Quieting Tilt-Rotor Aircraft

Actively induced harmonic blade-pitch oscillations reduce BVI noise. A method of reducing the noise generated by a tilt-rotor aircraft during descent involves active control of the blade pitch of the rotors. This method is related to prior such noise- reduction methods, of a type denoted generally as higher-harmonic control (HHC), in which the blade pitch is made to oscillate at a harmonic of the frequency of rotation of the rotor.

Posted in: Briefs, TSP, Mechanical Components

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Solar Array Panels With Dust-Removal Capability

Inexpensive, low-power piezoelectric buzzers would be built in. It has been proposed to incorporate piezoelectric vibrational actuators into the structural supports of solar photovoltaic panels, for the purpose of occasionally inducing vibrations in the panels in order to loosen accumulated dust. Provided that the panels were tilted, the loosened dust would slide off under its own weight. Originally aimed at preventing obscuration of photovoltaic cells by dust accumulating in the Martian environment, the proposal may also offer an option for the design of solar photovoltaic panels for unattended operation at remote locations on Earth.

Posted in: Briefs, TSP, Mechanical Components

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Autonomous Environment-Monitoring Networks

These neural networks recognize novel features in streams of input data. Autonomous environment-monitoring networks (AEMNs) are artificial neural networks that are specialized for recognizing familiarity and, conversely, novelty. Like a biological neural network, an AEMN receives a constant stream of inputs. For purposes of computational implementation, the inputs are vector representations of the information of interest. As long as the most recent input vector is similar to the previous input vectors, no action is taken. Action is taken only when a novel vector is encountered. Whether a given input vector is regarded as novel depends on the previous vectors; hence, the same input vector could be regarded as familiar or novel, depending on the context of previous input vectors. AEMNs have been proposed as means to enable exploratory robots on remote planets to recognize novel features that could merit closer scientific attention. AEMNs could also be useful for processing data from medical instrumentation for automated monitoring or diagnosis.

Posted in: Briefs, TSP, Information Sciences

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Improved Discrete Approximation of Laplacian of Gaussian

This method reduces the amount of circuitry needed for filtering of video data. An improved method of computing a discrete approximation of the Laplacian of a Gaussian convolution of an image has been devised. The primary advantage of the method is that without substantially degrading the accuracy of the end result, it reduces the amount of information that must be processed and thus reduces the amount of circuitry needed to perform the Laplacian-of-Gaussian (LOG) operation.

Posted in: Briefs, TSP, Information Sciences

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