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Simulation of Laser Cooling and Trapping in Engineering Applications

This design instrument shows good agreement with experimental measurements. An advanced computer code is undergoing development for numerically simulating laser cooling and trapping of large numbers of atoms. The code is expected to be useful in practical engineering applications and to contribute to understanding of the roles that light, atomic collisions, background pressure, and numbers of particles play in experiments using laser-cooled and -trapped atoms. The code is based on semiclassical theories of the forces exerted on atoms by magnetic and optical fields. Whereas computer codes developed previously for the same purpose account for only a few physical mechanisms, this code incorporates many more physical mechanisms (including atomic collisions, sub-Doppler cooling mechanisms, Stark and Zeeman energy shifts, gravitation, and evanescent-wave phenomena) that affect laser-matter interactions and the cooling of atoms to submillikelvin temperatures. Moreover, whereas the prior codes can simulate the interactions of at most a few atoms with a resonant light field, the number of atoms that can be included in a simulation by the present code is limited only by computer memory. Hence, the present code represents more nearly completely the complex physics involved when using laser-cooled and -trapped atoms in engineering applications.

Posted in: Information Sciences, Photonics, Briefs, TSP

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Adaptive Modeling Language and Its Derivatives

Modeling language enables automation of the entire product development cycle.Adaptive Modeling Language (AML), developed by TechnoSoft, Inc., is the underlying language of an object-oriented, multidisciplinary, knowledge-based engineering framework. TechnoSoft is a leading provider of object-oriented modeling and simulation technology used for commercial and defense applications. AML offers an advanced modeling paradigm with an open architecture, enabling the automation of the entire product development cycle, integrating product configuration, design, analysis, visualization, production planning, inspection, and cost estimation.

Posted in: Information Sciences, Briefs

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Integrating Terrain Maps Into a Reactive Navigation Strategy

Traversability of terrain is taken into account as an integral part of navigation. An improved method of processing information for autonomous navigation of a robotic vehicle across rough terrain involves the integration of terrain maps into a reactive navigation strategy. Somewhat more precisely, the method involves the incorporation, into navigation logic, of data equivalent to regional traversability maps. The terrain characteristic is mapped using a fuzzy-logic representation of the difficulty of traversing the terrain. The method is robust in that it integrates a global path-planning strategy with sensor-based regional and local navigation strategies to ensure a high probability of success in reaching a destination and avoiding obstacles along the way. The sensor-based strategies use cameras aboard the vehicle to observe the regional terrain, defined as the area of the terrain that covers the immediate vicinity near the vehicle to a specified distance a few meters away. The method at an earlier stage of development was described in “Navigating a Mobile Robot Across Terrain Using Fuzzy Logic” (), NASA Tech Briefs, Vol. 27, No. 2 (February 2003), page 5a. A recent update on the terrain classification stage of the method was reported in “Quantifying Traversability of Terrain for a Mobile Robot” (), NASA Tech Briefs, Vol. 29, No. 7 (July 2005), page 56. To recapitulate: The basic building blocks of the method are three behaviors that focus on successively smaller spatial scales and are integrated (in the sense of blended) through gains or weighting factors to generate speed and steering commands. The weighting factors are generated by fuzzy logic rules that take account of the current status of the vehicle.

Posted in: Information Sciences, Briefs, TSP

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Reducing Centroid Error Through Model-Based Noise Reduction

Corrections are made for bias and noise.A method of processing the digitized output of a charge-coupled device (CCD) image detector has been devised to enable reduction of the error in computed centroid of the image of a point source of light. The method involves model-based estimation of, and correction for, the contributions of bias and noise to the image data. The method could be used to advantage in any of a variety of applications in which there are requirements for measuring precise locations of, and/or precisely aiming optical instruments toward, point light sources.

Posted in: Information Sciences, Briefs, TSP

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NASA's Aviation Safety and Modeling Project

Capabilities for automated analysis of flight data are under development. The Aviation Safety Monitoring and Modeling (ASMM) Project of NASA’s Aviation Safety program is cultivating sources of data and developing automated computer hardware and software to facilitate efficient, comprehensive, and accurate analyses of the data collected from large, heterogeneous databases throughout the national aviation system. The ASMM addresses the need to provide means for increasing safety by enabling the identification and correcting of predisposing conditions that could lead to accidents or to incidents that pose aviation risks.

Posted in: Information Sciences, Briefs, TSP

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Developing Signal-Pattern-Recognition Programs

Software system aids development of application programs that analyze signals. An automated system to assist a General Aviation (GA) pilot in improving situational awareness of weather in flight is now undergoing development. This development is prompted by the observation that most fatal GA accidents are attributable to loss of weather awareness. Loss of weather awareness, in turn, has been attributed to the difficulty of interpreting traditional pre-flight weather briefings and the difficulty of both obtaining and interpreting traditional in-flight weather briefings. The developmental automated system not only improves weather awareness but also substantially reduces the time a pilot must spend in acquiring and maintaining weather awareness.

Posted in: Information Sciences, Briefs, TSP

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Statistical Detection of Atypical Aircraft Flights

A priori specification of search criteria is not necessary.

Posted in: Information Sciences, Briefs, TSP

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