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Semi-Supervised Eigenbasis Novelty Detection

Recent discoveries in high-time-resolution radio astronomy data have focused attention on a new class of events. Fast transients are rare pulses of radio frequency energy lasting from microseconds to seconds that might be produced by a variety of exotic astrophysical phenomena. For example, X-ray bursts, neutron stars, and active galactic nuclei are all possible sources of short-duration, transient radio signals. It is difficult to anticipate where such signals might appear, and they are most commonly discovered through analysis of high-time-resolution data that had been collected for other purposes. Transients are often faint and difficult to detect, so improved detection algorithms can directly benefit the science yield of all such commensal monitoring.

Posted in: Information Sciences, Briefs

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Modeling the Behavior of a Polymer Electrolyte Membrane within a Fuel Cell

Multiphysics software enables accurate membrane modeling in studying physical and electrical behavior of fuel cells. Scientists have deemed the fuel cell as one of the most promising power sources that can replace the use of fossil fuels as well as satisfy global expectations. The polymer electrolyte membrane fuel cell shows great potential to power homes and vehicles. A special class of fuel cell — Proton Exchange Membrane Fuel Cell (PEMFC) — was investigated during this study. The membrane of the PEMFC is one of the most fundamental parts of the cell, as its properties have great impact on the cell’s output capability.

Posted in: Information Sciences, Briefs

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Discrete Data Qualification System and Method Comprising Noise Series Fault Detection

Noise fault detector detects an unreasonably high or low variance or standard deviation. A Sensor Data Qualification (SDQ) function has been developed that allows the onboard flight computers on NASA’s launch vehicles to determine the validity of sensor data to ensure that critical safety and operational decisions are not based on faulty sensor data. This SDQ function includes a novel noise series fault detection algorithm for qualification of the output data from LO2 and LH2 low-level liquid sensors. These sensors are positioned in a launch vehicle’s propellant tanks in order to detect propellant depletion during a rocket engine’s boost operating phase. This detection capability can prevent the catastrophic situation where the engine operates without propellant. The output from each LO2 and LH2 low-level liquid sensor is a discrete valued signal that is expected to be in either of two states, depending on whether the sensor is immersed (wet) or exposed (dry). Conventional methods for sensor data qualification, such as threshold limit checking, are not effective for this type of signal due to its discrete binary-state nature.

Posted in: Information Sciences, Briefs

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Software Method for Computed Tomography Cylinder Data Unwrapping, Re-slicing, and Analysis

Visualization of the data is possible in one view without having to rotate the volume rendering. A software method has been developed that is applicable for analyzing cylindrical and partially cylindrical objects inspected using computed tomography (CT). This method involves unwrapping and re-slicing data so that the CT data from the cylindrical object can be viewed as a series of 2D sheets (or flattened “onion skins”) in addition to a series of top view slices and 3D volume rendering. The advantages of viewing the data in this fashion are as follows: (1) the use of standard and specialized image processing and analysis methods is facilitated having 2D array data versus a volume rendering; (2) accurate lateral dimensional analysis of flaws is possible in the unwrapped sheets versus volume rendering; (3) flaws in the part “jump out” at the inspector with the proper contrast expansion settings in the unwrapped sheets; and (4) it is much easier for the inspector to locate flaws in the unwrapped sheets versus top view slices for very thin cylinders. The method is fully automated and requires no input from the user except proper voxel dimension from the CT experiment and wall thickness of the part.

Posted in: Information Sciences, Briefs, TSP

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Video Altimeter and Obstruction Detector for an Aircraft

Video-based altimetric and obstructiondetection systems for aircraft have been partially developed. The hardware of a system of this type includes a downward-looking video camera, a video digitizer, a Global Positioning System receiver or other means of measuring the aircraft velocity relative to the ground, a gyroscopebased or other attitude-determination subsystem, and a computer running altimetric and/or obstruction-detection software.

Posted in: Information Sciences, Briefs

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Mixed Integer Programming and Heuristic Scheduling for Space Communication

Optimal planning and scheduling for a communication network was created where the nodes within the network are communicating at the highest possible rates while meeting the mission requirements and operational constraints. The planning and scheduling problem was formulated in the framework of Mixed Integer Programming (MIP) to introduce a special penalty function to convert the MIP problem into a continuous optimization problem, and to solve the constrained optimization problem using heuristic optimization.

Posted in: Information Sciences, Briefs

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Optimization of Turbine Blade Dovetail Geometry

Two-level optimization predicts designs with the least contact pressure and stress. The reliability of a gas or steam turbine is strongly dependent on the structural design of its blades. In land-based power generation units, turbine blades are connected to the turbine disk by a dovetail joint or fastener. As the turbine rotates, the dovetail experiences centrifugal loading including contact pressure and Mises stress. Efforts to improve turbine system efficiency increase the severity of temperature and pressure operating conditions, putting greater structural demands on the blades.

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