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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

The parent magmas of the SNC meteorites

Mineral compositions, partition coefficients, and computer-graphic representations of liquidus phase boundaries are used here to calculate parent magma compositions for Nakhla, Chassigny, and the xenocryst assemblage in EETA79001B, ALHA77005, and the EETA79001A groundmass. The calculated SNC parent magma compositions have low concentrations of Al2O3 and widely varying wollastonitite (CaO) component. In this regard they resemble basaltic komatiites, but their range of Wo is more extensive than that of basaltic komatiites and trace element characteristics are different. The calculated Nakhla parent magma has an unusually high Wo content and does not resemble any other known magmatic composition. A model of SNC petrogenesis is proposed.

Longhi, J.↗
NASA NTRS1989

Monte Carlo simulation of an expanding gas

By application of simple computer graphics techniques, the statistical performance of two Monte Carlo methods used in the simulation of rarefied gas flows are assessed. Specifically, two direct simulation Monte Carlo (DSMC) methods developed by Bird and Nanbu are considered. The graphics techniques are found to be of great benefit in the reduction and interpretation of the large volume of data generated, thus enabling important conclusions to be drawn about the simulation results. Hence, it is discovered that the method of Nanbu suffers from increased statistical fluctuations, thereby prohibiting its use in the solution of practical problems.

Boyd, Iain D.↗
NASA NTRS1990

Spectral Analysis Of Linear, Shift-Invariant Interpolants

Method of analysis provides quantitative measure of reconstruction and interpolation performances of linear, shift-invariant interpolants. Criterion of performance based upon mean-square error of difference between sampled and reconstructed functions. Applicable to reconstruction algorithms used in processing of signals and images and to types of interpolants used in numerical analysis, computer-aided design, and computer graphics.

Lansing, Donald L.↗
NASA NTRS1989

Engineering visualization utilizing advanced animation

Engineering visualization is the use of computer graphics to depict engineering analysis and simulation in visual form from project planning through documentation. Graphics displays let engineers see data represented dynamically which permits the quick evaluation of results. The current state of graphics hardware and software generally allows the creation of two types of 3D graphics. The use of animated video as an engineering visualization tool is presented. The engineering, animation, and videography aspects of animated video production are each discussed. Specific issues include the integration of staffing expertise, hardware, software, and the various production processes. A detailed explanation of the animation process reveals the capabilities of this unique engineering visualization method. Automation of animation and video production processes are covered and future directions are proposed.

Sabionski, Gunter R.↗
NASA NTRS1989

Using an instrumented manikin for Space Station Freedom analysis

One of the most intriguing and complex areas of current computer graphics research is animating human figures to behave in a realistic manner. Believable, accurate human models are desirable for many everyday uses including industrial and architectural design, medical applications, and human factors evaluations. For zero-gravity (0-g) spacecraft design and mission planning scenarios, they are particularly valuable since 0-g conditions are difficult to simulate in a one-gravity Earth environment. At NASA/JSC, an in-house human modeling package called PLAID is currently being used to produce animations for human factors evaluation of Space Station Freedom design issues. Presented here is an introductory background discussion of problems encountered in existing techniques for animating human models and how an instrumented manikin can help improve the realism of these models.

Orr, Linda↗
NASA NTRS1989

Man-in-the-control-loop simulation of manipulators

A method to achieve man-in-the-control-loop simulation is presented. Emerging real-time dynamics simulation suggests a potential for creating an interactive design workstation with a human operator in the control loop. The recursive formulation for multibody dynamics simulation is studied to determine requirements for man-in-the-control-loop simulation. High speed computer graphics techniques provides realistic visual cues for the simulator. Backhoe and robot arm simulations are implemented to demonstrate the capability of man-in-the-control-loop simulation.

Chang, J. L.↗
NASA NTRS1990

Computer simulation of gear tooth manufacturing processes

The use of computer graphics to simulate gear tooth manufacturing procedures is discussed. An analytical basis for the simulation is established for spur gears. The simulation itself, however, is developed not only for spur gears, but for straight bevel gears as well. The applications of the developed procedure extend from the development of finite element models of heretofore intractable geometrical forms, to exploring the fabrication of nonstandard tooth forms.

Mavriplis, Dimitri↗
NASA NTRS1989

Telepresence system development for application to the control of remote robotic systems

The recent developments of techniques which assist an operator in the control of remote robotic systems are described. In particular, applications are aimed at two specific scenarios: The control of remote robot manipulators; and motion planning for remote transporter vehicles. Common to both applications is the use of realistic computer graphics images which provide the operator with pertinent information. The specific system developments for several recently completed and ongoing telepresence research projects are described.

Crane, Carl D., III↗
NASA NTRS1989

ROTEX-TRIIFEX: Proposal for a joint FRG-USA telerobotic flight experiment

The concepts and main elements of a RObot Technology EXperiment (ROTEX) proposed to fly with the next German spacelab mission, D2, are presented. It provides a 1 meter size, six axis robot inside a spacelab rack, equipped with a multisensory gripper (force-torque sensors, an array of range finders, and mini stereo cameras). The robot will perform assembly and servicing tasks in a generic way, and will grasp a floating object. The man machine and supervisory control concepts for teleoperation from the spacelab and from ground are discussed. The predictive estimation schemes for an extensive use of time-delay compensating 3D computer graphics are explained.

Hirzinger, G.↗
NASA NTRS1989

Flight telerobotic servicer control from the Orbiter

The research and work conducted on the development of a testbed for a display and control panel for the Flight Telerobotic Servicer (FTS) are presented. Research was conducted on both software and hardware needed to control the FTS. A breadboard was constructed and placed into a mockup of the aft station of the Orbiter spacecraft. This breadboard concept was then evaluated using a computer graphics representation of the Tinman FTS. Extensive research was conducted on the software requirements and implementation. The hardware selected for the breadboard was 'flight like' and in some cases fit and function evaluated. The breadboard team studied some of the concepts without pursuing in depth their impact on the Orbiter or other missions. Assumptions are made concerning payload integration.

Ward, Texas M.↗
NASA NTRS1988

A 'transient' automated mapping procedure for complex geometries

A numerical procedure is presented which is applicable to the general curvilinear mappings of complex geometries and is unrestricted by slow convergence or strong dependence on the initial conditions of physical space. The scheme, employing a time-dependent factored-implicit scheme, is shown to be general and robust. In the illustrative applications presented, complex, closed geometries are routinely mapped even when they begin with unreasonable initial conditions created through the analytical and computer graphics inputs. Due to the natural damping introduced into the governing equations, fast convergence is achieved and high stability is observed.

Raad, Peter E.↗
NASA NTRS1989

Visions of visualization aids - Design philosophy and observations

Aids for the visualization of high-dimensional scientific or other data must be designed. Simply casting multidimensional data into a two-dimensional or three-dimensional spatial metaphor does not guarantee that the presentation will provide insight or a parsimonious description of phenomena implicit in the data. Useful visualization, in contrast to glitzy, high-tech, computer-graphics imagery, is generally based on preexisting theoretical beliefs concerning the underlying phenomena. These beliefs guide selection and formatting of the plotted variables. Visualization tools are useful for understanding naturally three-dimensional data bases such as those used by pilots or astronauts. Two examples of such aids for spatial maneuvering illustrate that informative geometric distortion may be introduced to assist visualization and that visualization of complex dynamics alone may not be adequate to provide the necessary insight into the underlying processes.

Ellis, Stephen R.↗
NASA NTRS1989

Scientific work environments in the next decade

The applications of contemporary computer graphics to scientific visualization is described, with emphasis on the nonintuitive problems. A radically different approach is proposed which centers on the idea of the scientist being in the simulation display space rather than observing it on a screen. Interaction is performed with nonstandard input devices to preserve the feeling of being immersed in the three-dimensional display space. Construction of such a system could begin now with currently available technology.

Gomez, Julian E.↗
NASA NTRS1991

Software For Depiction Of Three-Dimensional Objects

HME (Hierarchical Modeling Environment) is three-dimensional computer-graphics software system designed to give user complete access to total hierarchical mathematical model. Enables user to build, manipulate, and display hierarchical three-dimensional objects dynamically. Also includes created polygons in hierarchy. Establishes and edits proper coordination of eye points, sources of light, and connectivity of model necessary for accurate depiction of model. Written in C language.

Taylor, Frank↗
NASA NTRS1990

Manual Control Aspects of Orbital Flight

A brief description of several laboratories' current research in the general area of manual control of orbital flight is presented. With an operational-space-station era (and its increased traffic levels) approaching, now is an opportune time to investigate issues such as docking and rendezvous profiles and course-planning aids. The tremendous increase in the capabilities of computers and computer graphics has made extensive study possible and economical. It is time to study these areas, from a human factors and manual control perspective in order to preclude the occurrence of problems analogous to those that occurred in the airline and other related industries.

Brody, Adam R.↗
NASA NTRS1991

Three-dimensional perspective visualization

It was demonstrated that image processing computer graphic techniques can provide an effective means of physiographic analysis of remotely sensed regions through the use of three-dimensional perspective rendering. THe methods used to simulate and animate three-dimensional surfaces from two-dimensional imagery and digital elevation models are explained. A brief historic look at JPL's efforts in this field and several examples of animations, illustrating the evolution of these techniques from 1985, are shown. JPL's current research in this area is discussed along with examples of technology transfer and potential commercial application. The software is part of the VICAR (Video Image Communication and Retrieval) image processing system which was developed at the Multimission Image Processing Laboratory of JPL.

Hussey, Kevin↗
NASA NTRS1989

Quantitative computer simulations of extraterrestrial processing operations

The automation of a small, solid propellant mixer was studied. Temperature control is under investigation. A numerical simulation of the system is under development and will be tested using different control options. Control system hardware is currently being put into place. The construction of mathematical models and simulation techniques for understanding various engineering processes is also studied. Computer graphics packages were utilized for better visualization of the simulation results. The mechanical mixing of propellants is examined. Simulation of the mixing process is being done to study how one can control for chaotic behavior to meet specified mixing requirements. An experimental mixing chamber is also being built. It will allow visual tracking of particles under mixing. The experimental unit will be used to test ideas from chaos theory, as well as to verify simulation results. This project has applications to extraterrestrial propellant quality and reliability.

Vincent, T. L.↗