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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

IV and V Issues in Achieving High Reliability and Safety in Critical Control System Software

Risk analysis and integrated verification and validation are two important elements in a plan for ensuring the safety of critical software systems. We describe an approach we are currently developing for integrating risk analysis, and metrics analysis, and propose a fault predictor that would integrate the results of these activities. Practical difficulties associated with our approach are also discussed, as are limitations of the proposed predictor. We conclude with a discussion of what as been learned to date, and with suggestions for future work.

validation software reliability software risk asse↗
NASA NTRS1995

Parallel Climate Data Assimilation PSAS Package Achieves 18 GFLOPs on 512-Node Intel Paragon

Several algorithms were added to the Physical-space Statistical Analysis System (PSAS) from Goddard, which assimilates observational weather data by correcting for different levels of uncertainty about the data and different locations for mobile observation platforms. The new algorithms and use of the 512-node Intel Paragon allowed a hundred-fold decrease in processing time.

weather prediction climate modeling data assimilat↗
NASA NTRS2005

Achieving control and interoperability through unified model-based systems and software engineering

Control and interoperation of complex systems is one of the most difficult challenges facing NASA's Exploration Systems Mission Directorate. An integrated but diverse array of vehicles, habitats, and supporting facilities, evolving over the long course of the enterprise, must perform ever more complex tasks while moving steadily away from the sphere of ground support and intervention.

control↗
NASA NTRS2004

Organizational management practices for achieving software process improvement

The crisis in developing software has been known for over thirty years. Problems that existed in developing software in the early days of computing still exist today. These problems include the delivery of low-quality products, actual development costs that exceed expected development costs, and actual development time that exceeds expected development time. Several solutions have been offered to overcome out inability to deliver high-quality software, on-time and within budget. One of these solutions involves software process improvement. However, such efforts often fail because of organizational management issues. This paper discusses business practices that organizations should follow to improve their chances of initiating and sustaining successful software process improvement efforts.

software process improvement↗
NASA NTRS2006

Use of Virtual Mission Operations Center Technology to Achieve JPDO's Virtual Tower Vision

The Joint Program Development Office has proposed that the Next Generation Air Transportation System (NGATS) consolidate control centers. NGATS would be managed from a few strategically located facilities with virtual towers and TRACONS. This consolidation is about combining the delivery locations for these services not about decreasing service. By consolidating these locations, cost savings in the order of $500 million have been projected. Evolving to spaced-based communication, navigation, and surveillance offers the opportunity to reduce or eliminate much of the ground-based infrastructure cost. Dynamically adjusted airspace offers the opportunity to reduce the number of sectors and boundary inconsistencies; eliminate or reduce "handoffs;" and eliminate the distinction between Towers, TRACONS, and Enroute Centers. To realize a consolidation vision for air traffic management there must be investment in networking. One technology that holds great potential is the use of Virtual Mission Operations Centers to provide secure, automated, intelligent management of the NGATS. This paper provides a conceptual framework for incorporating VMOC into the NGATS.

Ivancic, William D.↗
NASA NTRS2007

Coordination and Cooperation to Achieve the GEOSS Space Segment: A Systems Approach

Established in April 2007, the SEO has made significant accomplishments in the support of CEOS and the virtual constellations. These accomplishments include (1) constellation trade studies for Atmospheric Composition and Land Surface Imaging, (2) a new engineering framework for requirements definition, assessment and architecture planning, (3) completion of a draft requirements document and gap analysis for the Atmospheric Composition Virtual Constellation, and (4) the development of a DVD video highlighting CEOS and the Virtual Constellation concept.

Killough, Brian D., Jr.↗
NASA NTRS2007

Terahertz lasers and amplifiers based on resonant optical phonon scattering to achieve population inversion

The present invention provides quantum cascade lasers and amplifier that operate in a frequency range of about 1 Terahertz to about 10 Terahertz. In one aspect, a quantum cascade laser of the invention includes a semiconductor heterostructure that provides a plurality of lasing modules connected in series. Each lasing module includes a plurality of quantum well structure that collectively generate at least an upper lasing state, a lower lasing state, and a relaxation state such that the upper and the lower lasing states are separated by an energy corresponding to an optical frequency in a range of about 1 to about 10 Terahertz. The lower lasing state is selectively depopulated via resonant LO-phonon scattering of electrons into the relaxation state.

Hu, Qing↗
NASA NTRS2008

Achieving Workplace Health through Application of Wellness Strategies

Purpose: 1) Understand and measure JSC workplace health: a) levels, sources, indicators & effects of negative, work-related stress; b) define leading indicators of emerging issues. 2 Provide linkage to outcomes: a) Focus application of wellness strategies & HR tools; b) Increase quality of work life and productivity. 3) Current effort will result in: a) Online assessment tool; b) Assessment of total JSC population (civil service & contractors); c) Application of mitigation tools and strategies. 4) Product of the JSC Employee Wellness Program. 5) Collaboration with Corporate Health Improvement Program/University of Arizona.

Robinson, Judith L.↗
NASA NTRS2008

Seeking Augmented Information Content Concerning Diurnal Precipitation Achieved by Combining TRMM-PR and CloudSat-CPR Radar Data Sets

The CloudSat satellite's Cloud Profiling Radar (CPR) is a highly sensitive 94 GHz (W-band) nadir viewing radar system flown in retrograde sun synchronous orbit useful for determining the vertical structure of cloud hydrometeors down to sensitivity of approx. -30 dBZ reflectivity factor. Given this sensitivity, it is possible to unambiguously measure precipitation rates in clouds over a spectrum extending from approx. 0.08 - 3.0 mm hr (sup -1) down to altitudes of 0.5 km with approx.0.25 km vertical binning. This enables an effective means to measure a great deal of the drizzle and light rain spectrum. However, because of its near-polar sunsynchronous orbit, CloudSat cannot sample the diurnal cycle of precipitation, nor with its nadir-only CPR view can it obtain a high duty cycle in sampling precipitation at fixed local times over fixed positions. On the other hand, the TRMM satellite, which is flown in a non-sunsynchronous 35-degree inclined orbit carrying the 13.8 GHz KU-band Precipitation Radar (PR) scanning through nadir over an approx. 225 km swath, can sample both the diurnal cycle and with a much improved duty cycle relative to CloudSat. Moreover, the PR and CPR have the same 0.25 km vertical binning capability. The PR's greatest shortcoming is its approx. +17 dBZ sensitivity, which eliminates the possibility of measuring rain rates below -0.3-0.5 mm hr(sup -1), which can involve rainfall accumulations of up to 50% of the total over some regions. This begs the question of whether by combining CPR and PR data sets, whether it is possible to obtain an augmented measurement of the diurnal precipitation cycle. By collecting complimentary datasets during CloudSat and TRMM satellite orbit crossings within a delta t = 45-min proximity window, it is possible to demonstrate that whenever TRMM detects a precipitation signal, the correlations along the vertical axis between the reflectivities acquired from the CPR and PR are in inverse proportion to the magnitude of the delta t proximity window. By taking advantage of these underlying correlations, it is possible to develop a functional which can be used to broaden the reflectivity spectrum, concomitantly the rain rate spectrum, of the PR measurements based on the inherently broader reflectivity spectrum of the CPR at the lower reflectivity end of the spectrum, concomitantly at lighter rain rates. With the functional in place, it is then possible to produce synthetic CloudSat precipitation imagery over the PR track and thus over the diurnal time period. These augmented data are then used to study the spectral-vertical diurnal properties of precipitation over oceanic regions observed by TRMM.

Smith, Eric A.↗
NASA NTRS2009

IT Project Success w\7120 and 7123 NPRs to Achieve Project Success

This slide presentation reviews management techniques to assure information technology development project success. Details include the work products, the work breakdown structure (WBS), system integration, verification and validation (IV&V), and deployment and operations. An example, the NASA Consolidated Active Directory (NCAD), is reviewed.

Walley, Tina L.↗