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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Planetary-scale characteristics of the atmospheric circulation during January and February 1979

The global scale mass and wind fields observed during FGGE special observing period (SOP) are studied, with attention given to the time variation and vertical structure of the ultralong waves. A spherical harmonic representation is developed for the global fields. The tropical circulation is found to imprint more amplitude on the lower-order components than the midlatitude circulation does. High amplitude oscillations are determined to be present in the divergent fields on all time scales, i.e., diurnal to monthly. The global scale wind was found to change on scales approaching a week. Good agreement with teleconnection predictions was demonstrated for the cross-equatorial divergent and zonal rotational flow changes. The global scale was concluded to resemble force modes of linear tidal theory, with important contributions from longitudinal heating gradients.

Paegle, J.↗
NASA NTRS1984

Comparison of GLAS retrieved cloud fields with model generated rainfall fields

Monthly mean fractional cloud cover for January and February 1979, retrieved from SOP 1 of FGGE, are compared with the total precipitation field derived diagonally from the GLAS analysis/forecast system for the same time period. The breakdown of cloudiness into day (3 AM) and night (3 PM) is consistent with maps of outgoing long wave and short wave radiation inferred from AVHRR data. Of the many regions of coincidence, there is a particularly striking phenomenon: west of the coast of Peru, at about 20 deg S, there is a distinct small scale maximum in precipitation which coincides precisely with a maximum in the cloudiness field. This maximum in cloudiness and precipitation does not appear in the NOAA/NESS fields of albedo and outgoing long wave radiation which are normally sensitive to cloud fields. These low level clouds with warm tops are a mainly nocturnal phenomenon.

Susskind, J.↗
NASA NTRS1984

Forecast Impact of Components of the FGGE Observing System

Experiments have been conducted to assess the summer and winter forecast impact of the FGGE system, and of its main observing components: temperature sounding data derived from the TIROS-N polar orbiting satellite, cloud track winds determined from geostationary satellite observations and drifting buoy data which were collected by satellite during FGGE. The Analysis/Forecast System used has a number of improvements upon the system utilized by Halen et al. (1982) for the FGGE Special Observing Period-1 (SOP-1). Several modifications were made in the analysis scheme, the most important being the interpolation of the analysis minus 6 h forecast deviations rather than of the analyzed fields themselves. The forecast model is still the 4 deg lat, 5 deg lon and 9 vertical levels GLAS Fourth Order GCM with several minor corrections implemented in the physics and numerics. The improved vertical interpolation in the analysis resulted in better assimilation of rawinsonde data, which has more vertical structure than satellite data. As a result, there was an improvement of the forecasts derived from conventional data only, and, consequently, a small reduction of the positive impact of satellite data from that obtained by Halem et al. (1982).

Kalnay, E.↗
NASA NTRS1984

Global Scale Diagnosis of FGGE Data

The objective was to perform descriptive global-scale diagnoses of the Goddard Laboratory for Atmospheric Sciences (GLAS) First GARP Global Experiment (GLAS) SOP-1 analyses and to compare these diagnoses against controlled, real-data integrations of the GLAS General Circulation Model (GCM) as well as other data sets. The effects of critical latitudes, the diagnoses of the influence of tropical wind data and latent heating upon the GLAS GCM, investigations of planetary wave structure on various time scales from the diurnal to the monthly, and comparison of the GLAS analyses with other analyses are discussed.

Paegle, J.↗
NASA NTRS1985

Global scale diagnoses of FGGE data

Descriptive global scale diagnoses of the First Global Atmospheric Research Experiment SOP-1 analyses were made and compared against controlled, real data integrations of the Goddard Laboratory of Atmospheric Science (GLAS) general circulation model (GCM) as well as other data sets. The effects of critical latitudes were studied; the influence of tropical wind data and latent heating upon the GLAS GCM was diagnosed; planetary wave structure on various time scales from the diurnal to the monthly was studied; and the GLAS analyses were compared with other analyses. Short term controlled GLAS GCM integrations show that: (1) the inclusion of tropical wind data in real data integrations has an important influence in the mid-latitude prediction in both hemispheres; and (2) the tropical divergent wind reacts almost immediately to alteration of the tropical latent heating. The presence or absence of zonally averaged easterlies depends strongly upon the presence of tropical latent heating.

Paegle, J.↗
NASA NTRS1986

Vertical structure of the wind field during the Special Observing Period I of the Global Weather Experiment

The vertical structure of the global atmosphere is analyzed for selected periods of the Special Observing Period I (SOP-I) for the Global Weather Experiment (GWE). The analysis consists of projection of the stream-function and velocity potential at 200 and 850 mb on spherical harmonics and of the wind and height fields on the normal modes of a linearized form of the primitive equations for a basic state at rest. The kinematic vertical structure is discussed in terms of correlation coefficients of the 200 mb and 850 mb winds and analysis of the internal and external normal modes of the primitive equations. The reliability of the results is checked by applying the same analysis methods to data sets obtained from three different institutions: Geophysical Fluid Dynamics Laboratory (GFDL), European Center for Medium Range Weather Forecasting (ECMWF), and Goddard Laboratory for the Atmospheres (GLA). It is found that, on a global basis, vertically reversing circulations are as important as the equivalent barotropic structures. For the verticaly reversing components, the gravity and mixed Rossby-gravity modes have contributions of the same order of magnitude as those of the Rossby modes in tropical latitudes.

Paegle, J. N.↗
NASA NTRS1986

Moisture transports and budgets of 'moisture bursts'

The paper discusses moisture fluxes and budgets associated with a pair of 'moisture bursts' in the eastern North Pacific Ocean area, described by Smith et al. (1985). The moisture fluxes were calculated using data obtained during the first Special Observing Period (SOP-1) of the FGGE. The area specifically examined extended from the equator to the latitude 20 deg N and from longitude 180 deg to 100 deg W, with concentration on the region south and southeast of the Hawaiian Islands. From the comparison of the calculations based on dropwindsonde and radiosonde data and reports from commercial and military aircraft, it is concluded that the calculations of water vapor flow across latitude lines probably provide a fair representation of reality, especially when based on the dropwindsonde data. However, water vapor flow out of small volumes is not well represented by the results from either data.

Thompson, A. H.↗
NASA NTRS1987

Significance of the South Pacific Convergence Zone (SPCZ) in the energy budget of the Southern Hemisphere tropics

An in-depth investigation of the energetics, including boundary transports, was conducted on four equal-area regions in the tropical Southern Hemisphere during the SOP-1 period in 1979. The regions, each approximately centered on one of the wave axes of maximum warm rising air, include the SPCZ (115 deg W - 155 deg E) and the Australian (155-65 deg E), the African (65 deg E - 25 deg W), and the South American (25-115 deg W) regions. Daily variations of the energy conversions were examined, and time-averaged result of energy contents, conversions, and boundary transports were compiled for January 10-27. Results show that the eddy kinetic energy (KE) exceeds the eddy available potential energy (AE) in all four regions, with the largest excess being in the SPCZ. Of the conversion and flux terms, only the conversion of AE to KE is significant (again, with the greatest value in the SPCZ). An evaluation of boundary fluxes of KE indicates that the only significant transport between regions is a flow of KE from the SPCZ region into the South American region.

Hurrell, James W.↗
NASA NTRS1987

Spacelab Data Processing Facility (SLDPF) quality assurance expert systems development

The Spacelab Data Processing Facility (SLDPF) is an integral part of the Space Shuttle data network for missions that involve attached scientific payloads. Expert system prototypes were developed to aid in the performance of the quality assurance function of the Spacelab and/or Attached Shuttle Payloads processed telemetry data. The Spacelab Input Processing System (SIPS) and the Spacelab Output Processing System (SOPS), two expert systems, were developed to determine their feasibility and potential in the quality assurance of processed telemetry data. The capabilities and performance of these systems are discussed.

Basile, Lisa R.↗
NASA NTRS1986

Independent Orbiter Assessment (IOA): Analysis of the extravehicular mobility unit

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Extravehicular Mobility Unit (EMU) hardware. The EMU is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for the Shuttle crewmember to perform Extravehicular Activity (EVA) in Earth orbit. Two EMUs are included on each baseline Orbiter mission, and consumables are provided for three two-man EVAs. The EMU consists of the Life Support System (LSS), Caution and Warning System (CWS), and the Space Suit Assembly (SSA). Each level of hardware was evaluated and analyzed for possible failure modes and effects. The majority of these PCIs are resultant from failures which cause loss of one or more primary functions: pressurization, oxygen delivery, environmental maintenance, and thermal maintenance. It should also be noted that the quantity of PCIs would significantly increase if the SOP were to be treated as an emergency system rather than as an unlike redundant element.

Raffaelli, Gary G.↗
NASA NTRS1989

Global atmospheric moisture variability

Research efforts during FY-88 have focused on completion of several projects relating to analysis of FGGE data during SOP-1 and on expanded studies of global atmospheric moisture. In particular, a revised paper on the relationship between diabatic heating and baroclinicity in the South Pacific Convergence Zone (SPCZ) was submitted. A summary of completed studies on diagnostic convective parameterization was presented at the Satellite Meteorology and Oceanography Convergence last February. These investigations of diabatic heating in the SPCZ have demonstrated the requirement for a more quantitative description of atmospheric moisture. As a result, efforts were directed toward use of passive remote microwave measurements from the Nimbus-7 SMMR and the DOD's Special Sensor Microwave Imager (SSMI/I) as critical sources of moisture data. Activities this year are summarized.

Robertson, Franklin R.↗
NASA NTRS1992

The diagnosis of a preblocking explosively-developing extratropical cyclone system

This paper presents the diagnosis of an extratropical cyclone that developed explosively from 18 to 19 January 1979 over the North Atlantic Ocean. The diagnosis applies data obtained from the Goddard Laboratory for Atmospheres FGGE SOP-1 level III-b global analyses on a 4 deg latitude by 5 deg longitude grid to the extended height tendency and the Zwack-Okossi development equations. The cyclone developed initially in response to cyclonic vorticity advection downstream from an upper air through, warm air advection in a strongly baroclinic region, and latent heat release in the cyclone domain. As development continued, thermal advection and latent heat release increased their role in forcing height falls in the cyclone domain, while the influence of vorticity advection decreased. Finally, development ceased when anticyclonic vorticity advection below 700 mb and adiabatic cooling in the ascending air combined to neutralize the influence of warm air advection and latent heat release.

Uhl, Mary A.↗
NASA NTRS1991

Philosophy, policies, and procedures - The three P's of flight-deck operations

Standard operating procedures are drafted and provided to flightcrews to dictate the manner in which tasks are carried out. Failure to conform to Standard Operating Procedures (SOP) is frequently listed as the cause of violations, incidents, and accidents. However, procedures are often designed piecemeal, rather than being based on a sound philosophy of operations and policies that follow from such a philosophy. A framework of philosophy, policies, and procedures is proposed.

Degani, Asaf↗
NASA NTRS1992

A diagnosis of the explosive development of two extratropical cyclones

This paper examines the 24-h explosive development periods of two extratropical cyclones, the first occurring over the Gulf Stream off the coast of New England from 18 to 19 January 1979 and the second occurring over the southeastern United States from 20 to 21 January 1979. The data used in this study are the First GARP (Global Atmospheric Research Program) Global Experiment (FGGE) level IIIb (SOP I) global analyses on a 4 deg latitude x 5 deg longitude grid. The parameter used to diagnose development is the geostrophic relative vorticity tendency calculated using an extended form of the Zwack-Okossi development equation. This development equation is similar to the Petterssen-Sutcliffe development equation, but is shown to be more complete by explicitly coupling surface development with forcing at all levels above the surface. Cyclonic-vorticity advection, warm-air advection, and latent heat release act to develop the two cyclones, while adiabatic cooling in the ascending air opposes development. Further, vertical profiles of the development quantities for these two cases reveal that vorticity and temperature advection maximize in the 200-300-mb layer, while the latent heat release maximum is typically below 500 mb.

Lupo, Anthony R.↗
NASA NTRS1991

Single phase dynamic CMOS PLA using charge sharing technique

A single phase dynamic CMOS NOR-NOR programmable logic array (PLA) using triggered decoders and charge sharing techniques for high speed and low power is presented. By using the triggered decoder technique, the ground switches are eliminated, thereby, making this new design much faster and lower power dissipation than conventional PLA's. By using the charge-sharing technique in a dynamic CMOS NOR structure, a cascading AND gate can be implemented. The proposed PLA's are presented with a delay-time of 15.95 and 18.05 nsec, respectively, which compare with a conventional single phase PLA with 35.5 nsec delay-time. For a typical example of PLA like the Signetics 82S100 with 16 inputs, 48 input minterms (m) and 8 output minterms (n), the 2-SOP PLA using the triggered 2-bit decoder is 2.23 times faster and has 2.1 times less power dissipation than the conventional PLA. These results are simulated using maximum drain current of 600 micro-A, gate length of 2.0 micron, V sub DD of 5 V, the capacitance of an input miniterm of 1600 fF, and the capacitance of an output minterm of 1500 fF.

Dhong, Y. B.↗
NASA NTRS1991

Canonical multi-valued input Reed-Muller trees and forms

There is recently an increased interest in logic synthesis using EXOR gates. The paper introduces the fundamental concept of Orthogonal Expansion, which generalizes the ring form of the Shannon expansion to the logic with multiple-valued (mv) inputs. Based on this concept we are able to define a family of canonical tree circuits. Such circuits can be considered for binary and multiple-valued input cases. They can be multi-level (trees and DAG's) or flattened to two-level AND-EXOR circuits. Input decoders similar to those used in Sum of Products (SOP) PLA's are used in realizations of multiple-valued input functions. In the case of the binary logic the family of flattened AND-EXOR circuits includes several forms discussed by Davio and Green. For the case of the logic with multiple-valued inputs, the family of the flattened mv AND-EXOR circuits includes three expansions known from literature and two new expansions.

Perkowski, M. A.↗
NASA NTRS1994

Integrating planning and reactive control

Our research is developing persistent agents that can achieve complex tasks in dynamic and uncertain environments. We refer to such agents as taskable, reactive agents. An agent of this type requires a number of capabilities. The ability to execute complex tasks necessitates the use of strategic plans for accomplishing tasks; hence, the agent must be able to synthesize new plans at run time. The dynamic nature of the environment requires that the agent be able to deal with unpredictable changes in its world. As such, agents must be able to react to unanticipated events by taking appropriate actions in a timely manner, while continuing activities that support current goals. The unpredictability of the world could lead to failure of plans generated for individual tasks. Agents must have the ability to recover from failures by adapting their activities to the new situation, or replanning if the world changes sufficiently. Finally, the agent should be able to perform in the face of uncertainty. The Cypress system, described here, provides a framework for creating taskable, reactive agents. Several features distinguish our approach: (1) the generation and execution of complex plans with parallel actions; (2) the integration of goal-driven and event driven activities during execution; (3) the use of evidential reasoning for dealing with uncertainty; and (4) the use of replanning to handle run-time execution problems. Our model for a taskable, reactive agent has two main intelligent components, an executor and a planner. The two components share a library of possible actions that the system can take. The library encompasses a full range of action representations, including plans, planning operators, and executable procedures such as predefined standard operating procedures (SOP's). These three classes of actions span multiple levels of abstraction.

Wilkins, David E.↗
NASA NTRS1995

A diagnosis of the development of a winter anticyclone over North America

This paper examines the 48-h life cycle of a winter anticyclone occurring over North America from 18 to 20 January 1979 using Goddard Laboratory for Atmospheres FGGE level 3b (SOP 1) global analyses on a 4 deg latitude by 5 deg longitude grid. Applying the relatively new methodology of the Zwack-Okossi equation, results show that anticyclonic vorticity advection and cold-air advection acted to develop the anticyclone, while adiabatic warming in the descending air opposed development. Other forcing processes made only small contributions to anticyclone changes. Vertical profiles of the development quantities reveal that vorticity and temperature advections, as well as the adiabatic warming, maximized in the 200-300-mb layer.

King, Melinda L.↗