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Google Earth Offline Cache Pre-loader v1 (GEOCP)

GEOCP gives disaster responders better and more reliable access to information in the field, while minimizing the amount of effort required before deployment. Ames Research Center, Moffett Field, California Google Earth is a geospatial browser produced by Google that allows interactive exploration of the world from data servers on the Internet. An integral part of Google Earth is a built-in “cache” that is stored locally on the user’s computer, and allows the user to later revisit previously viewed regions (even if the network link is disrupted or unavailable). The Google Earth cache is filled as the user interacts with Google Earth (i.e., flying and zooming the interface). The Google Earth Offline Cache Pre-loader (GEOCP) is a tool that allows users to specify a region to cache, and controls Google Earth to automatically and systematically fill the Google Earth cache. While connected to the Internet, the user specifies a latitude/longitude box, and a desired height above the ground. GEOCP then commands Google Earth to view the requested area in a lawnmower pattern, which has the side effect of bringing those areas into the Google Earth cache. When finished, the user is free to disconnect the network and continue to view the area.

Posted in: Briefs, Electronics & Computers, Software

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Robustness Analysis and Robust Design of Uncertain Systems

Langley Research Center, Hampton, Virginia A methodology was developed for the analysis and design of systems subject to parametric uncertainty in which design requirements are specified via hard inequality constraints. Hard constraints are those that must be satisfied for all parameter realizations within a given uncertainty model. Uncertainty models are given by norm-bounded perturbations from a nominal parameter value (i.e., hyperspheres) and by sets of independently bounded uncertain variables (i.e., hyperrectangles). These models, which are also quite practical, allow for a rigorous mathematical treatment within the proposed framework. Hardconstraint feasibility is determined by sizing the largest uncertainty set for which the design requirements are satisfied.

Posted in: Briefs, Electronics & Computers, Software

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XDB3 Extension for Equality and Relational Operators

Ames Research Center, Moffett Field, California While keyword full-text searches work well for textual data, they do not work well for numeric, date, or other more highly structured information. In particular, Netmark/XDB could retrieve any record where the author contained “Knight” in the text, but could not return only those records from Calendar Year 2010 that have “Knight” in their author section. Traditional relational databases allow for rich comparison “relational” operators; for example, one can express a query such as “return all rows where the signature date is on January 1, 2010.” Netmark/XDB, being primarily targeted at XML processing and retrieving XML-structured data, was designed for full-text querying to find keywords. Most other XML indexing and querying systems also are designed with the assumption that content (“CDATA”) is textual or binary data that can be queried against, but not with relational comparison operators like “greater than a value.”

Posted in: Briefs, Electronics & Computers, Software

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Simulator for a Self-Stabilizing Synchronization Protocol for Arbitrary Digraphs

Langley Research Center, Hampton, Virginia This work was conducted to create a means of simulating and visualizing the behavior of a self-stabilizing distributed clock synchronization protocol developed at LaRC (Langley Research Center). The protocol has many applications including projects that directly pertain to work being done at NASA. Time synchronization is a critical component of many projects, from computer networking and distributed systems, to autonomous flight. This easy-to-understand interface both displays accurate information concerning the protocol, and conveys its utility.

Posted in: Briefs, Electronics & Computers, Software

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Testing Encapsulation of Internet, DTN, and LTP Traffic over AOS Space Data Link Protocol

NASA’s Jet Propulsion Laboratory, Pasadena, California The CCSDS ENCAP Over AOS Over UDP software engine encapsulates live Internet Protocol (IP), DTN Bundle Protocol (BP), or Licklider Transport Protocol (LTP) traffic over a Consultative Committee for Space Data Systems (CCSDS)-compliant Encapsulation Ser vice (ENCAP) running over an Advanced Orbiting Systems (AOS) data link protocol UDP stream. Many space missions currently use the AOS protocol, and this software is an implementation of a standard mechanism to encapsulate Internet Protocol traffic (including interactive Web applications and streaming video) and DTN Bundle Protocol traffic (for large file transfers over high latency links) over ENCAP over AOS.

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Predicting Magnetospheric Relativistic >1 MeV Electrons

NASA’s Jet Propulsion Laboratory, Pasadena, California There is an association between High-Intensity Long-Duration Continuous AE (HILDCAA) activity intervals and the acceleration of relativistic >1 MeV electrons in the magnetosphere. All of the HILDCAAs that occurred in solar cycle 23 (SC23) from 1995 to 2008 led to the acceleration of E>0.6 MeV, >2.0 MeV, and >4.0 MeV electrons in the Earth’s outer radiation belts. What is particularly noteworthy is that the E>0.6 MeV electron acceleration was delayed ~1.0 day after the onset of the HILDCAA event, the E>2.0 MeV electrons delayed ~1.5 days after the onset of the HILDCAA event, and the E>4.0 MeV electrons delayed ~2.5 days after the onset of the HILDCAA event.

Posted in: Briefs, Software

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Optimal Prioritized Actuator Allocation

This allocation could improve the safety and autonomy of missions where it is critical to match torque first to minimize disturbances to spacecraft pointing. NASA’s Jet Propulsion Laboratory, Pasadena, California For formation flying, rendezvous and docking, and proximity operations with small bodies of the solar system, spacecraft require simultaneous translational and rotational agility. The necessary agility is generally provided by combinations of multiple small thrusters and torque-only actuators. To use these actuators, an onboard control system first calculates desired forces and torques that cause a spacecraft to follow a desired trajectory. Then the commanded forces and torques are turned into individual commands to specific actuators such that the combined action of all the actuators realizes as closely as possible the commanded forces and torques. This problem is referred to as actuator (or control) allocation.

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