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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Mission analysis techniques for attached Shuttle payloads

Visibility times, i.e., times which desired targets are visible to a payload, are examined for attached Shuttle payloads. These times are affected by a number of constraints. Some constraints are examined along with mathematical or computer modeling techniques used to determine their effects. The constraints include: occultation of the earth, moon, and sun, and limb avoidance angles of each; orbit parameters such as inclination and ascending node, along with sensitivity to changes in each; TDRSS acquisition; South Atlantic Anomaly (SAA) avoidance, nighttime viewing only; bright earth avoidance angles; the field of view; Shuttle attitude, and Orbiter operational constraints. All of this information is integrated and, with computer programs, a schedule of observations and Shuttle attitudes is obtained.

Lambros, S.↗
NASA NTRS1982

Mollier-I, S-Diagrams for Combustion Gases in Data Processing

In order to have all the thermal and caloric states of combustion gases accessible in a computer, closed mathematical approximation equations were established for the real factors, the enthalpy and the entropy of a real combustion gas. The equations approximate the various effects of molecular forces real gas influence and dissociation - at temperatures of 200 K to 6,000 K, pressures of 0.001 to 1,000 bar, and in the range from stoichiometric composition to air. A system of subprograms is listed in FORTRAN, by means of which thermodynamic calculations can be carried out in the same manner as with Mollier I,S diagrams.

Zacharias, F.↗
NASA NTRS1985

Heat pipe modeling and simulation

Presented herein is a parametric study of the defining equations which govern the steady state operational characteristics of the Grumman Monogroove Dual Passage Heat Pipe. These defining equations are combined to develop a mathematical model which describes and predicts the operational and performance capabilities of a specific heat pipe, given the necessary physical characteristics and working fluid. Included is a brief review of the current literature, a discussion of the governing equations, and a description of both the mathematical and computer model. Final results of preliminary test runs of the model are presented and compared with experimental tests performed by Grumman on actual prototypes.

Peterson, G. P.↗
NASA NTRS1989

Adaptive Control Of Remote Manipulator

Robotic control system causes remote manipulator to follow closely reference trajectory in Cartesian reference frame in work space, without resort to computationally intensive mathematical model of robot dynamics and without knowledge of robot and load parameters. System, derived from linear multivariable theory, uses relatively simple feedforward and feedback controllers with model-reference adaptive control.

Seraji, Homayoun↗
NASA NTRS1990

Ames vision group research overview

A major goal of the reseach group is to develop mathematical and computational models of early human vision. These models are valuable in the prediction of human performance, in the design of visual coding schemes and displays, and in robotic vision. To date researchers have models of retinal sampling, spatial processing in visual cortex, contrast sensitivity, and motion processing. Based on their models of early human vision, researchers developed several schemes for efficient coding and compression of monochrome and color images. These are pyramid schemes that decompose the image into features that vary in location, size, orientation, and phase. To determine the perceptual fidelity of these codes, researchers developed novel human testing methods that have received considerable attention in the research community. Researchers constructed models of human visual motion processing based on physiological and psychophysical data, and have tested these models through simulation and human experiments. They also explored the application of these biological algorithms to applications in automated guidance of rotorcraft and autonomous landing of spacecraft. Researchers developed networks for inhomogeneous image sampling, for pyramid coding of images, for automatic geometrical correction of disordered samples, and for removal of motion artifacts from unstable cameras.

Watson, Andrew B.↗
NASA NTRS1990

Applications of different design methodologies in navigation systems and development at JPL

The NASA/JPL deep space navigation system consists of a complex array of measurement systems, data processing systems, and support facilities, with components located both on the ground and on-board interplanetary spacecraft. From its beginings nearly 30 years ago, this system has steadily evolved and grown to meet the demands for ever-increasing navigation accuracy placed on it by a succession of unmanned planetary missions. Principal characteristics of this system are its capabilities and great complexity. Three examples in the design and development of interplanetary space navigation systems are examined in order to make a brief assessment of the usefulness of three basic design theories, known as normative, rational, and heuristic. Evaluation of the examples indicates that a heuristic approach, coupled with rational-based mathematical and computational analysis methods, is used most often in problems such as orbit determination strategy development and mission navigation system design, while normative methods have seen only limited use is such applications as the development of large software systems and in the design of certain operational navigation subsystems.

Thurman, S. W.↗
NASA NTRS1990

Verification of floating-point software

Floating point computation presents a number of problems for formal verification. Should one treat the actual details of floating point operations, or accept them as imprecisely defined, or should one ignore round-off error altogether and behave as if floating point operations are perfectly accurate. There is the further problem that a numerical algorithm usually only approximately computes some mathematical function, and we often do not know just how good the approximation is, even in the absence of round-off error. ORA has developed a theory of asymptotic correctness which allows one to verify floating point software with a minimum entanglement in these problems. This theory and its implementation in the Ariel C verification system are described. The theory is illustrated using a simple program which finds a zero of a given function by bisection. This paper is presented in viewgraph form.

Hoover, Doug N.↗
NASA NTRS1991

Earth observations and global change decision making: A special bibliography, 1991

The first section of the bibliography contains 294 bibliographic citations and abstracts of relevant reports, articles, and documents announced in 'Scientific and Technical Aerospace Reports (STAR)' and 'International Aerospace Abstracts (IAA)'. These abstracts are categorized by the following major subject divisions: aeronautics, astronautics, chemistry and materials, engineering, geosciences, life sciences, mathematical and computer sciences, physics, social sciences, space sciences and general. Following the abstract section, seven indexes are provided for further assistance.

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NASA NTRS1992

Stability margins for multilinear interval systems by way of phase conditions: A unified approach

A simple way of checking the stability with respect to an arbitrary stability region of a family of polynomials containing a vector of parameters varying within prescribed intervals is discussed. It is assumed that the parameters appear affine multilinearly in the characteristic polynomial coefficients. The condition proposed is simply to check the phase difference of the vertex polynomials. This test based on the mapping theorem significantly reduces computational complexity. Mathematical proofs are omitted. The results can be used to determine various stability margins of control systems containing interconnected interval subsystems. These include the gain, phase, time-delay, H(sup infinity), and nonlinear sector bounded stability margins of multilinear interval systems.

Keel, L. H.↗
NASA NTRS1993

European aerospace science and technology, 1992: A bibliography with indexes

This bibliography contains 1916 annotated references to reports and journal articles of European intellectual origin entered into the NASA Scientific and Technical Information System during 1992. Representative subject areas include: spacecraft and aircraft design, propulsion technology, chemistry and materials, engineering and mechanics, earth and life sciences, communications, computers and mathematics, and the natural space sciences.

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NASA NTRS1988

Software engineering as an engineering discipline

The following topics are discussed in the context of software engineering: early use of the term; the 1968 NATO conference; Barry Boehm's definition; four requirements fo software engineering; and additional criteria for software engineering. Additionally, the four major requirements for software engineering--computer science, mathematics, engineering disciplines, and excellent communication skills--are discussed. The presentation is given in vugraph form.

Berard, Edward V.↗
NASA NTRS1990

Optimization of rotor blades for combined structural, dynamic, and aerodynamic properties

Optimal helicopter blade design with computer-based mathematical programming has received more and more attention in recent years. Most of the research has focused on optimum dynamic characteristics of rotor blades to reduce vehicle vibration. There is also work on optimization of aerodynamic performance and on composite structural design. This research has greatly increased our understanding of helicopter optimum design in each of these aspects. Helicopter design is an inherently multidisciplinary process involving strong interactions among various disciplines which can appropriately include aerodynamics; dynamics, both flight dynamics and structural dynamics; aeroelasticity: vibrations and stability; and even acoustics. Therefore, the helicopter design process must satisfy manifold requirements related to the aforementioned diverse disciplines. In our present work, we attempt to combine several of these important effects in a unified manner. First, we design a blade with optimum aerodynamic performance by proper layout of blade planform and spanwise twist. Second, the blade is designed to have natural frequencies that are placed away from integer multiples of the rotor speed for a good dynamic characteristics. Third, the structure is made as light as possible with sufficient rotational inertia to allow for autorotational landing, with safe stress margins and flight fatigue life at each cross-section, and with aeroelastical stability and low vibrations. Finally, a unified optimization refines the solution.

He, Cheng-Jian↗
NASA NTRS1993

NASA aerospace database subject scope: An overview

Outlined here is the subject scope of the NASA Aerospace Database, a publicly available subset of the NASA Scientific and Technical (STI) Database. Topics of interest to NASA are outlined and placed within the framework of the following broad aerospace subject categories: aeronautics, astronautics, chemistry and materials, engineering, geosciences, life sciences, mathematical and computer sciences, physics, social sciences, space sciences, and general. A brief discussion of the subject scope is given for each broad area, followed by a similar explanation of each of the narrower subject fields that follow. The subject category code is listed for each entry.

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NASA NTRS1993

Commonwealth of Independent States aerospace science and technology, 1992: A bibliography with indexes

This bibliography contains 1237 annotated references to reports and journal articles of Commonwealth of Independent States (CIS) intellectual origin entered into the NASA Scientific and Technical Information System during 1992. Representative subject areas include the following: aeronautics, astronautics, chemistry and materials, engineering, geosciences, life sciences, mathematical and computer sciences, physics, social sciences, and space sciences.

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NASA NTRS1994

Transformation of two and three-dimensional regions by elliptic systems

Several reports are attached to this document which contain the results of our research at the end of this contract period. Three of the reports deal with our work on generating surface grids. One is a preprint of a paper which will appear in the journal Applied Mathematics and Computation. Another is the abstract from a dissertation which has been prepared by Ahmed Khamayseh, a graduate student who has been supported by this grant for the last two years. The last report on surface grids is the extended abstract of a paper to be presented at the 14th IMACS World Congress in July. This report contains results on conformal mappings of surfaces, which are closely related to elliptic methods for surface grid generation. A preliminary report is included on new methods for dealing with block interfaces in multiblock grid systems. The development work is complete and the methods will eventually be incorporated into the National Grid Project (NGP) grid generation code. Thus, the attached report contains only a simple grid system which was used to test the algorithms to prove that the concepts are sound. These developments will greatly aid grid control when using elliptic systems and prevent unwanted grid movement. The last report is a brief summary of some timings that were obtained when the multiblock grid generation code was run on the Intel IPSC/860 hypercube. Since most of the data in a grid code is local to a particular block, only a small fraction of the total data must be passed between processors. The data is also distributed among the processors so that the total size of the grid can be increase along with the number of processors. This work is only in a preliminary stage. However, one of the ERC graduate students has taken an interest in the project and is presently extending these results as a part of his master's thesis.

Mastin, C. Wayne↗
NASA NTRS1994

The Technical Information Library: TIB

The Technische Informationsbibliothek Hannover (TIB) is the German national central library for all areas of technology and related sciences, especially chemistry, computer science, mathematics, and physics. The TIB acquires and makes available a comprehensive collection of conventional and non-conventional literature, especially foreign material, with particular emphasis on specialized new publications which are difficult to obtain or in difficult languages.

Rosemann, Uwe↗
NASA NTRS1994

Remote sensing/global change. A special bibliography

The first portion of this bibliography contains citations (with abstracts, when available) to unclassified literature contained in the NASA STI Database. These citations also appeared in issues of the abstract journal 'Scientific and Technical Aerospace Reports (STAR)', or in other announcement products offered by the NASA STI Program. The citations appear in ascending accession number order. A second section provides several indexes to the citations. They are subject term, personal author, report number, and accession number. The citations are included for the following disciplines as they relate to remote sensing and global change: astronautics, engineering, geosciences, life sciences, mathematical and computer sciences, social sciences, and space sciences.

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NASA NTRS1995

Aeronautical engineering: A continuing bibliography with indexes (supplement 316)

This bibliography lists 413 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1995. Subject coverage includes: aeronautics; mathematical and computer sciences; chemistry and material sciences; geosciences; design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics.

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