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Fast Algorithms for Model-Based Diagnosis

Methods based on Boolean functions and linear programming are more practical for complex systems. Two improved new methods for automated diagnosis of complex engineering systems involve the use of novel algorithms that are more efficient than prior algorithms used for the same purpose. Both the recently developed algorithms and the prior algorithms in question are instances of model-based diagnosis, which is based on exploring the logical inconsistency between an observation and a description of a system to be diagnosed.

Posted in: Information Sciences, Briefs, TSP

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Biased Randomized Algorithm for Fast Model-Based Diagnosis

The bias increases the likelihood of making a minimal diagnosis.

Posted in: Information Sciences, Briefs, TSP

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Two Methods for Efficient Solution of the Hitting-Set Problem

A paper addresses much of the same subject matter as that of “Fast Algorithms for Model-Based Diagnosis” (NPO-30582), which appears elsewhere in this issue of NASA Tech Briefs.

Posted in: Information Sciences, Briefs, TSP

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In Situ Electrochemical Deposition of Microscopic Wires

Tedious, expensive post-growth assembly is no longer necessary.

Posted in: Manufacturing & Prototyping, Briefs, TSP

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Parylene C as a Sacrificial Material for Microfabrication

Parylene C has been investigated for use as a sacrificial material in microfabrication. Although Parylene C cannot be patterned lithographically like photoresists, it nevertheless extends the range of processing options by offering a set of properties that are suitable for microfabrication and are complementary to those of photoresists. The compatibility of Parylene C with several microfabrication processes was demonstrated in experiments in which a thin film of Parylene C was deposited on a silicon wafer, then several thin metal films were deposited and successfully patterned, utilizing the Parylene C pads as a sacrificial layer.

Posted in: Manufacturing & Prototyping, Briefs

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Race Car Manufacturer Uses Finite Element Analysis to Simulate Chassis Performance

Building a Formula 1 race car requires accurate analysis of structural features and constraints. The monocoque chassis of a Formula 1 race car is a sandwich structure, made of high-performance carbon-epoxy composite face sheets and an aluminum or aramidic honeycomb core. High-modulus and high-strength composites, with aerospace-class toughened epoxy resins, are used in order to obtain the maximum safety performance/weight ratio. All attachment points for the engine, suspensions, rollhoop, etc., are made through inserts embedded in the lamination stack during the production phase. In order to minimize weight and thermal expansion differential, and maximize the adhesion, the inserts are made as thick (about 18-mm) laminated composite plates to be machined to the required dimensions and thickness.

Posted in: Manufacturing & Prototyping, Briefs

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Multilayer Composite Pressure Vessels

Lightweight tanks can be made in diverse sizes and shapes.

Posted in: Manufacturing & Prototyping, Briefs

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