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Maximum-Likelihood Template Matching

This algorithm features a robust measure of matching and an efficient search technique. An improved algorithm for detecting gray-scale and binary templates in digitized images has been devised. The greatest difference between this algorithm and prior template-detecting algorithms stems from the measure used to determine the quality or degree of match between a template and given portion of an image. This measure is based on a maximum-likelihood formulation of the template- matching problem; this measure, and the matching performance obtained by use of it, are more robust than are those of prior template-matching algorithms, most of which utilize a sum-of-squared-differences measure. Other functions that the algorithm performs along with template matching include subpixel localization, estimation of uncertainty, and optimal selection of features. This algorithm is expected to be useful for detecting templates in digital images in a variety of applications, including recognition of objects, ranging by use of stereoscopic images, and tracking of moving objects or features. (For the purpose of tracking, features or objects recognized in an initial image could be used as templates for matching in subsequent images of the same scene.)

Posted in: Briefs, TSP

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New Technique Improves Cirrus Cloud Characterization

Radiometric measurements at submillimeter-wavelength accurately characterize cirrus cloud properties. A new technique for retrieving cirrus properties from radiometric measurements at submillimeter wavelengths has been developed. The technique can accurately measure the amount of ice present in cirrus clouds, determine the median crystal size, and constrain crystal shape. The retrieval algorithm improves upon prior algorithms by also retrieving middle and upper tropospheric water-vapor profiles in concert with cloud properties. This joint-analysis method corrects for retrieval errors introduced by water vapor in and near the cloud.

Posted in: Briefs, TSP

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Magnetically Moved Trim Masses for Fine Position Control

Control would be achieved without spurious effects generated by propulsion systems. Systems of caged trim masses manipulated by magnetic fields have been proposed for effecting fine control of the positions and/or orientations of spacecraft. The systems were conceived for use during observations by spaceborne interferometers, the component instruments of which (1) are located on multiple spacecraft flying in formation and (2) are required to be kept aligned with each other within narrow position and orientation tolerances. The proposed systems would make it possible to avoid the spurious effects generated by the spacecraft propulsion systems that would otherwise have to be used for fine position control; the spurious effects would include vibrations, exhaust, and flashes of light, which would be detrimental to the interferometric observations. Terrestrial versions of the proposed systems might be useful for fine horizontal positioning of delicate scientific instruments.

Posted in: Mechanics, Briefs, TSP

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Software for Designing Actively Controlled Structures

One program offers capabilities heretofore available only in separate programs. SMARTCOM is a computer program for the analysis and design of actively controlled “smart” structures. Typically, an actively controlled “smart” structure incorporates piezoelectric sensors and actuators that are used, in conjunction with an electrical control system, to damp vibrations. As is the case for other structures, the analysis and design of actively controlled “smart” structures is often best accomplished with the help of finite-element computer programs. Unfortunately, prior finite-element codes do not offer coupled analyses of the mechanical, electrical, and thermal properties of “smart”-structure materials. Also, they are not directly linked with control software, making it necessary to use separate finite-element and control programs to analyze controlled structures. Furthermore, the programs used heretofore to design “smart” structures do not offer capabilities for optimization or for probabilistic or fuzzy analysis.

Posted in: Mechanics, Briefs, TSP

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Testing Soil for Electrokinetically Enhanced Bioremediation

Data from tests provide guidance for in situ treatment. The term “prefield test” denotes an in situ test of contaminated soil in preparation for in situ treatment of the soil by a method called “electrokinetically enhanced bioremediation” (EEB). A prefield test yields data that are helpful in designing and operating an efficient and cost-effective EEB system.

Posted in: Materials, Briefs, TSP

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Software for Network Processing of

The Electronic Portable Information Collection (EPIC) computer program is a computer system that processes work authorization documents (WADs). The EPIC System, which is also known as the Portable Data Collection System, comprises a central data server and portable data terminals. The central data server acts as the host on a local-area network and maintains the WAD data in Structured Query Language (SQL) and a database. The portable data terminals are desktop, laptop, and pen-based tablet computers that run, variously, the Windows 95 or Windows NT operating system and are connected to the central data server via the network.

Posted in: Software, Briefs

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Software for Analyzing Valve-Actuator

A computer program assists engineers in analyzing data on the performances of actuators of fuel and oxidizer valves in the main engines of the space shuttle. The program could be adapted to similar use in other settings in which, as in the space shuttle, valve actuators are instrumented to provide data on commanded versus actual actuator positions. The program acquires such data during a specified diagnostic procedure in which valves are opened and closed. The program processes the data and generates several indications of performance, including trend plots, delta command minus actual positions plots, ramp-rate plots, error-from-command plots, and the means and standard deviations of the plotted quantities. The advantage afforded by the program is that it gives more information than does a simple pass/fail testing criterion. By looking at engineering performance profiles generated by this program during tests performed at different times, the engineers can identify valves that are about to fail in time to replace them.

Posted in: Software, Briefs

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