Tech Briefs

Verifying Diagnostic Software

Livingstone PathFinder (LPF) is a simulation-based computer program for verifying autonomous diagnostic software. LPF is designed especially to be applied to NASA's Livingstone computer program, which implements a qualitative-model-based algorithm that diagnoses faults in a complex automated system (e.g.,an exploratory robot, spacecraft, or aircraft). LPF forms a software test bed containing a Livingstone diagnosis engine, embedded in a simulated operating environment consisting of a simulator of the system to be diagnosed by Livingstone and a driver program that issues commands and faults according to a non-deterministic scenario provided by the user. LPF runs the test bed through all executions allowed by the scenario, checking for various selectable error conditions after each step. All components of the test bed are instrumented, so that execution can be single-stepped both backward and forward. The architecture of LPF is modular and includes generic interfaces to facilitate substitution of alternative versions of its different parts. Altogether, LPF provides a flexible, extensible framework for simulation-based analysis of diagnostic software; these characteristics also render it amenable to application to diagnostic programs other than Livingstone.

Posted in: Briefs, TSP, Software


Neuropsychological Testing of Astronauts

The Spaceflight Cognitive Assessment Tool for Windows (WinSCAT) is a computer program that administers a battery of five timed neuro-cognitive tests.WinSCAT was developed to give astronauts an objective and automated means of assessing their cognitive functioning during space flight, as compared with their own baseline performances measured during similar prior testing on the ground. WinSCAT is also intended for use by flight surgeons to assess cognitive impairment after exposure of astronauts to such cognitive assaults as head trauma, decompression sickness,and exposure to toxic gas. The tests were selected from among a group of tests, denoted the Automated Neuropsychological Assessment Metrics, that were created by the United States Navy and Army for use in evaluating the cognitive impairment of military personnel who have been subjected to medication or are suspected to have sustained brain injuries.These tests have been validated in a variety of clinical settings and are now in the public domain. The tests are presented in a Microsoft Windows shell that facilitates administration and enables immediate reporting of test scores in numerical and graphical forms.

Posted in: Briefs, Software


Miniature Robotic Submarine for Exploring Harsh Environments

Extreme miniaturization would enable exploration of previously inaccessible regions. The miniature autonomous submersible explorer (MASE) has been proposed as a means of scientific exploration—especially, looking for signs of life—in harsh, relatively inaccessible underwater environments. Basically, the MASE would be a small instrumented robotic submarine (see figure) that could launch itself or could be launched from another vehicle. Examples of environments that might be explored by use of the MASE include subglacial lakes, deep-ocean hydrothermal vents, acidic or alkaline lakes, brine lenses in permafrost, and ocean regions under Antarctic ice shelves.

Posted in: Briefs, TSP, Mechanical Components


Lightweight Exoskeletons With Controllable Actuators

Resistive or assistive forces and torques would be generated on command. A proposed class of lightweight exoskeletal electromechanical systems would include electrically controllable actuators that would generate torques and forces that, depending on specific applications, would resist and/or assist wearers’ movements. The proposed systems would be successors to relatively heavy, bulky, and less capable human strength amplifying exoskeletal electromechanical systems that have been subjects of research during the past four decades. The proposed systems could be useful in diverse applications in which there are needs for systems that could be donned or doffed easily, that would exert little effect when idle, and that could be activated on demand: examples of such applications include (1) providing controlled movement and/or resistance to movement for physical exercise and (2) augmenting wearers’ strengths in the performance of military, law-enforcement, and industrial tasks.

Posted in: Briefs, TSP, Mechanical Components


Progress in Fabrication of Rocket Combustion Chambers by VPS

Several documents in a collection describe aspects of the development of advanced materials and fabrication processes intended to enable the manufacture of advanced rocket combustion chambers and nozzles at relatively low cost. One concept discussed in most of the documents is the fabrication of combustion-chamber liners by vacuum plasma spraying (VPS) of an alloy of 88Cu/8Cr/4Nb (numbers indicate atomic percentages)—a concept that was reported in "Improved Alloy for Fabrication of Combustion Chambers by VPS" (MFS-26546), NASA Tech Briefs, Vol. 23, No.1 (January 1999), page 50. Another concept is the deposition of graded-composition wall and liner structures by VPS in order to make liners integral parts of wall structures and to make oxidation-and thermal- protection layers integral parts of liners: The VPS process is started at 100 percent of a first alloy, then the proportion of a second alloy is increased gradually from zero as deposition continues, ending at 100 percent of the second alloy. Yet another concept discussed in one of the documents is the VPS of oxidation-protection coats in the forms of nickel-and-chromium-containing refractory alloys on VPS-deposited 88Cu/8Cr/4Nb liners.

Posted in: Briefs, Manufacturing & Prototyping


Indentured Parts List Maintenance and Part Assembly Capture Tool—IMPACT

Viewing and maintaining the complex assembly hierarchies of large databases is made easier. Johnson Space Center’s (JSC's) indentured parts list (IPL) maintenance and parts assembly capture tool (IMPACT) is an easy-to-use graphical interface for viewing and maintaining the complex assembly hierarchies of large databases. IMPACT, already in use at JSC to support the International Space Station (ISS), queries, updates, modifies, and views data in IPL and associated resource data, functions that it can also perform, with modification, for any large commercial database. By enabling its users to efficiently view and manipulate IPL hierarchical data, IMPACT performs a function unlike that of any other tool. Through IMPACT, users will achieve results quickly, efficiently, and cost effectively.

Posted in: Briefs, Information Sciences


Fast Query-Optimized Kernel-Machine Classification

Computation is accelerated by an order of magnitude, without loss of accuracy. A recently developed algorithm performs kernel-machine classification via incremental approximate nearest support vectors. The algorithm implements support-vector machines (SVMs) at speeds 10 to 100 times those attainable by use of conventional SVM algorithms. The algorithm offers potential benefits for classification of images, recognition of speech, recognition of handwriting, and diverse other applications in which there are requirements to discern patterns in large sets of data.

Posted in: Briefs, TSP, Information Sciences


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