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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

NASA Regional Planetary Image Facility

The Regional Planetary Image Facility (RPIF) provided access to data from NASA planetary missions and expert assistance about the data sets and how to order subsets of the collections. This ensures that the benefit/cost of acquiring the data is maximized by widespread dissemination and use of the observations and resultant collections. The RPIF provided education and outreach functions that ranged from providing data and information to teachers, involving small groups of highly motivated students in its activities, to public lectures and tours. These activities maximized dissemination of results and data to the educational and public communities.

Arvidson, Raymond E.↗
NASA NTRS1994

Design of Flight Vehicle Management Systems

As the operation of large systems becomes ever more dependent on extensive automation, the need for an effective solution to the problem of design and validation of the underlying software becomes more critical. Large systems possess much detailed structure, typically hierarchical, and they are hybrid. Information processing at the top of the hierarchy is by means of formal logic and sentences; on the bottom it is by means of simple scalar differential equations and functions of time; and in the middle it is by an interacting mix of nonlinear multi-axis differential equations and automata, and functions of time and discrete events. The lecture will address the overall problem as it relates to flight vehicle management, describe the middle level, and offer a design approach that is based on Differential Geometry and Discrete Event Dynamic Systems Theory.

Meyer, George↗
NASA NTRS1994

Dynamics of Numerics and CFD

This lecture attempts to illustrate the basic ideas of how the recent advances in nonlinear dynamical systems theory (dynamics) can provide new insights into the understanding of numerical algorithms used in solving nonlinear differential equations (DEs). Examples will be given of the use of dynamics to explain unusual phenomena that occur in numerics. The inadequacy of the use of linearized analysis for the understanding of long time behavior of nonlinear problems will be illustrated, and the role of dynamics in studying the nonlinear stability, accuracy, convergence property and efficiency of using time- dependent approaches to obtaining steady-state numerical solutions in computational fluid dynamics (CFD) will briefly be explained.

Yee, H. C.↗
NASA NTRS1995

Nonlinear Control and Discrete Event Systems

As the operation of large systems becomes ever more dependent on extensive automation, the need for an effective solution to the problem of design and validation of the underlying software becomes more critical. Large systems possesses much detailed structure, typically hierarchical, and they are hybrid. Information processing at the top of the hierarchy is by means of formal logic and sentences; on the bottom it is by means of simple scalar differential equations and functions of time; and in the middle it is by an interacting mix of nonlinear multi-axis differential equations and automata, and functions of time and discrete events. The lecture will address the overall problem as it relates to flight vehicle management, describe the middle level, and offer a design approach that is based on Differential Geometry and Discrete Event Dynamic Systems Theory.

Meyer, George↗
NASA NTRS1995

Numerical Solution of Multi-Dimensional Hyperbolic Conservation Laws on Unstructured Meshes

The lecture material will discuss the application of one-dimensional approximate Riemann solutions and high order accurate data reconstruction as building blocks for solving multi-dimensional hyperbolic equations. This building block procedure is well-documented in the nationally available literature. The relevant stability and convergence theory using positive operator analysis will also be presented. All participants in the minisymposium will be asked to solve one or more generic test problems so that a critical comparison of accuracy can be made among differing approaches.

Barth, Timothy J.↗
NASA NTRS1995

Experiments in High-Lift for High-Speed Civil Transports

The lecture will present experimental work pertaining to HSCT high-lift aerodynamic testing. The effects of Reynolds number and test techniques will be discussed. The performance of attached-flow and leading-edge vortex-control high-lift devices will also be presented. All of the aerodynamic data presented will be from experiments performed prior to the HSR program. The subject of airframe noise testing and its relevance to highlift testing will be discussed but no quantitative data will be presented.

Ross, James C.↗
NASA NTRS1995

Rotational And Rovibrational Energy Transfer In Electron Collisions With Molecules

Air flows around a hypervelocity reentry vehicle undergo dissociation, rovibrational excitation and ionization. More specifically the air, initially 80% N2 and 20% O2, in the shock layer consists of species such as N, O, N2, O2, NO, N+, O+, N+, O+, NO+ and 2 free electrons. It was pointed out in multi temperature models'' that the temperature of the rotational energy modes and the gas-kinetic translational temperature are quickly equilibrated by a few collisions and rise rapidly to high temperatures as 50000K before falling off to equilibrium value of 10000K. Contrary, the electronic and vibrational temperatures state energy distributions remain low (less than 15000K) because of the slow equilibration. Electron vibrational energy transfer is thought to play a crucial role in such a ionizing flow regime since chemical reaction rates and dissociation depend strongly on the vibrational temperatures. Modeling of these flowfields in principle require the rovibrational excitation and de-excitation cross section data for average electron energies from threshold up to several eV (leV=11605.4 K). In this lecture we focus on theoretical description of rotational effects i.e. energy transfer of electrons to molecules such that the molecular rotational (vojo goes to voj) or vibrational and rotational (v(sub 0)j(sub 0) goes to vj) states are changed. Excitation and de-excitation of electronic states was discussed in a previous talk at this conference.

Thuemmel, Helmar T.↗
NASA NTRS1996

A Cross-Industry Analysis of LOFT Debriefings

Line Oriented Simulation (LOS) iss widely used to provide crews opportunities to practice Cockpit Resource Management (CRM) concepts in realistic, challenging simulated flight situations. LOS includes both Line Oriented Flight Training (LOFT), the original "non-jeopardy" form in which the crews are not graded on their performance, and Line Oriented Evaluation (LOE). In LOE, crews are graded, which is required in those airlines that participate in the FAA's Advanced Qualification Program (ALP). How much crews learn in LOS arid take back to the line hinges on the effectiveness of the debriefing that follows the LOS. The simulation itself is a busy, intense experience, and thoughtful discussion afterwards is necessary for the crew to sort out and interpret what happened and why. Instructors are expected to lead briefings in a way that encourages crew members to analyze for themselves their performance in the LOS. Rather than lecturing the crew in the traditional manner on what they did right and wrong, the instructor is expected to facilitate self-discovery and self-critique by the crew. We have recently completed a study in which we observed 36 LOFT briefings at 5 major U.S. airlines. We audiotape recorded the briefings, transcribed the recordings, and coded for more than 70 variables. Our analysis addresses four broad questions: To what extent do instructors attempt to facilitate crew self-analysis? What techniques do instructors use to facilitate and how effective are these techniques? What is the character of crew participation? To what extent do briefings emphasize CRM and crew performance? We discuss the implications of our findings for ALP and LOE.

Dismukes, Key↗
NASA NTRS1996

Challenges and Accomplishments of Viscous Incompressible Flow Computations in Aerospace and Beyond

Recent progress in incompressible Navier-Stokes solution methods will be presented. Discussions are focused on the methods designed for complex geometry applications in three dimensions, and thus are limited to primitive variable formulation. Both steady- and unsteady-solution algorithms and their salient features are discussed. A summary of our recent progress in flow solver development is given followed by numerical studies of a few example problems of our current interest. Solvers discussed here are based on structured-grid approach using finite-difference or finite-volume frame work. This short course will be delivered in three one-our lectures. The material in the course are collected from the work performed by the Incompressible Navier-Stokes group at NASA Ames Research Center over the past several years, and can be found in our publications widely disseminated in the US and abroad. This short course is sponsored by AGARD Consultant and Exchange Program under Support Project P-110.

Kwak, Dochan↗
NASA NTRS2001

Adaptive Numerical Dissipation Controls for High Order Methods

A numerical scheme for direct numerical simulation of shock-turbulence interactions of high speed compressible flows would ideally not be significantly more expensive than the standard fourth or sixth-order compact or non-compact central differencing scheme. It should be possible to resolve all scales down to scales of order of the Kolmogorov scales of turbulence accurately and efficiently, while at the same time being able to capture steep gradients occurring at much smaller scales efficiently. The goal of this lecture is to review the progress and new development of the low dissipative high order shock-capturing schemes proposed by Yee et al. Comparison on the efficiency and accuracy of this class of schemes with spectral and the fifth-order WENO (weighted essentially nonoscillatory) scheme will be presented. A new approach to dynamically sense the appropriate amount of numerical dissipation to be added at each grid point using non-orthogonal wavelets will be discussed.

Yee, Helen C.↗
NASA NTRS1997

Astrobiology: Study of the Living Universe

Astrobiology is defined as the study of the living universe. This endeavor encompasses the use of space to understand life's origin, evolution, and destiny in the universe. Life's origin refers to understanding the origin of life in the context of the origin and diversity of planetary systems. Life's evolution refers to understanding how living systems have adapted to Earth's changing environment, to the all-pervasive force of gravity, and how they may adapt to environments beyond Earth. Life's destiny refers to making long-term human presence in space a reality, and laying the foundation for understanding and managing changes in Earth's environment. This lecture will explore the development of this field of inquiry, the science questions to be examined, and the mechanisms available for participation by the scientific community.

DeVincenzi, Donald L.↗
NASA NTRS1993

Regulatory Mechanism of Muscle Disuse Atrophy in Adult Rats

During the last phase of NAG 2-386 we completed three studies. The effects of 14 days of weightlessness; the vastus medialis (VM) from flight rats in COSMOS 2044 was compared with the VM from tail suspended rats and other controls. The type I and II fibers in the mixed fiber portion of the VM were significantly reduced in flight rats and capillary densities paralleled the fiber density changes. The results of this project compared favorably with those in the extensor digitorum longus following seven days of flight in SL 3. The cardiovascular projects focused on the blood pressure changes in head down tilted rats (HDT) and non-head down tilted (N-HDT) rats. Blood pressures (MAP, SP and DP) were significantly elevated through seven days of HDT and rapidly returned to control levels within one day after removal from the HDT position. The N-HDT showed some slight rise in blood pressure but these were not as great and they were not as rapid. The HDT rats were characterized as exhibiting transient hypertension. These results led to some of the microvascular and vascular graduate student projects of Dr. Bernhard Stepke. Also our results refute or, at least, do not agree with previous reports from other laboratories. Each animal, in our blood pressure projects, served as its own control thereby providing more accurate results. Also, our experiments focused on recovery studies which can, in and of themselves, provide guidelines for flight experiments concerned with blood pressure changes. Another experiment was conducted to examine the role of testicular atrophy in whole body suspended (WBS) and tail suspended (TS) rats. We worked in conjunction with Dr. D.R. Deaver's laboratory at Pennsylvania State University and Dr. R. P. Amann at Colorado State University. In the TS rats the testes are retracted into the abdominal cavity, unless a ligature is placed to maintain them in the external scrotal sac. The cryptorchid condition in TS rats results in atrophy of the testes and lowered levels of spermatid formation. Hormonal changes due to testes atrophy must be considered in future experiments where related effects may modify muscle, bone or other tissue changes. Also, some new assessments of past results (published by many researchers) may warrant revised interpretations. The blood pressure studies and the testicular function results were presented and reviewed during an invited lecture at the University of Bordeaux II during the Animals in Space Symposium in March 1993. In summary, each of these three projects complied with the objectives of the proposal and serve to demonstrate the utility of animal models in preparations and interpretations of space flight results. All funding has been expended in accordance with the approved budget.

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NASA NTRS2002

The Estimation Theory Framework of Data Assimilation

Lecture 1. The Estimation Theory Framework of Data Assimilation: 1. The basic framework: dynamical and observation models; 2. Assumptions and approximations; 3. The filtering, smoothing, and prediction problems; 4. Discrete Kalman filter and smoother algorithms; and 5. Example: A retrospective data assimilation system

Cohn, S.↗
NASA NTRS2002

An Introduction to High-Energy Astrophysics: Detectors, Techniques and Missions

A series of lectures will be given to acquaint the amateur astronomer with historical, present and future methods of observation in high-energy astrophysics. These will begin with the basic principles of how photons of high energy are detected and their energy measured. The detectors and data distribution methods will be described. Finally, a comprehensive description of the experiments and missions in high-energy astrophysics will be reviewed.

Fishman, Gerald J.↗
NASA NTRS2002

The Biogeochemistry of Benthic Photosynthetic Communities

Microbial mats are our earliest, and most pervasive evidence of life on Earth. In addition to their importance as the crucible of microbial evolution on Earth, microbial mats may be important in our search for life outside of our solar system. This lecture will introduce various types of microbial mats, and their fossilized counterparts, stromatolites by presenting examples of these communities. Biogeochemical cycles important in microbial mats will be introduced and discussed.

Bebout, Brad↗
NASA NTRS2002

Biogeochemical Cycling

This lecture will introduce the concept of biogeochemical cycling. The roles of microbes in the cycling of nutrients, production and consumption of trace gases, and mineralization will be briefly introduced.

Bebout, Brad↗
NASA NTRS2002

Global Surface Temperature Change and Uncertainties Since 1861

The objective of this talk is to analyze the warming trend and its uncertainties of the global and hemi-spheric surface temperatures. By the method of statistical optimal averaging scheme, the land surface air temperature and sea surface temperature observational data are used to compute the spatial average annual mean surface air temperature. The optimal averaging method is derived from the minimization of the mean square error between the true and estimated averages and uses the empirical orthogonal functions. The method can accurately estimate the errors of the spatial average due to observational gaps and random measurement errors. In addition, quantified are three independent uncertainty factors: urbanization, change of the in situ observational practices and sea surface temperature data corrections. Based on these uncertainties, the best linear fit to annual global surface temperature gives an increase of 0.61 +/- 0.16 C between 1861 and 2000. This lecture will also touch the topics on the impact of global change on nature and environment. as well as the latest assessment methods for the attributions of global change.

Shen, Samuel S. P.↗
NASA NTRS1990

NASA/State Education Cooperation

NASA is cooperating with state departments of education in a number of special education programs. An example is Maryland Summer Centers for Gifted and Talented Students sponsored by the Maryland State Department of Education. Some 2,600 students participated in the 1990 program. One of the 12 centers is the Center for Space Science and Technology at Goddard Space Flight Center, which provides instruction to students of the 9-12 grade level. This center is operated by a three organization partnership that includes the Maryland State Department of Education, the University of Maryland and Goddard Space Flight Center, which hosts the instructional program and provides volunteer scientists and engineers as instructors. Typical two-week space intern program includes panel discussions, lectures, tours, field trips and hands-on activity focusing on various space science topics. Senior high students benefit from a one-to-one mentor relationship with a volunteer scientist or engineer. Another example was the Paducah (Kentucky) NASA Community Involvement Project, a joint educational effort of Langley and Lewis Research Centers, Marshall Space Flight Center, the Kentucky Department of Education, the City of Paducah and Paducah Independent Schools. It was a 16 day exposition/symposium featuring seminars on space subjects.

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