Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Virtualization”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Virtual acoustics displays

The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.

Wenzel, Elizabeth M.↗
NASA NTRS1990

On the dynamics of space manipulators using the Virtual Manipulator, with applications to path planning

Robotic manipulators carried by future spacecraft are expected to perform important tasks in space, such as the servicing of satellites. However, the performance of these systems could be severely degraded by dynamic disturbances to the spacecraft caused by manipulator motions. This paper presents a method for representing the dynamics of space manipulator systems using the recently developed Virtual Manipulator (VM) concept. This representation is then applied to develop algorithms which can be used to plan manipulator motions that minimize disturbances of the spacecraft.

Vafa, Z.↗
NASA NTRS1990

Implementation of a virtual link between power system testbeds at Marshall Spaceflight Center and Lewis Research Center

The Marshall Space Flight Center (MSFC) owns and operates a space station module power management and distribution (SSM-PMAD) testbed. This system, managed by expert systems, is used to analyze and develop power system automation techniques for Space Station Freedom. The Lewis Research Center (LeRC), Cleveland, Ohio, has developed and implemented a space station electrical power system (EPS) testbed. This system and its power management controller are representative of the overall Space Station Freedom power system. A virtual link is being implemented between the testbeds at MSFC and LeRC. This link would enable configuration of SSM-PMAD as a load center for the EPS testbed at LeRC. This connection will add to the versatility of both systems, and provide an environment of enhanced realism for operation of both testbeds.

Doreswamy, Rajiv↗
NASA NTRS1992

Visually Coupled Systems (VCS): The Virtual Panoramic Display (VPD) System

The development and impact is described of new visually coupled system (VCS) equipment designed to support engineering and human factors research in the military aircraft cockpit environment. VCS represents an advanced man-machine interface (MMI). Its potential to improve aircrew situational awareness seems enormous, but its superiority over the conventional cockpit MMI has not been established in a conclusive and rigorous fashion. What has been missing is a 'systems' approach to technology advancement that is comprehensive enough to produce conclusive results concerning the operational viability of the VCS concept and verify any risk factors that might be involved with its general use in the cockpit. The advanced VCS configuration described here, was ruggedized for use in military aircraft environments and was dubbed the Virtual Panoramic Display (VPD). It was designed to answer the VCS portion of the systems problem, and is implemented as a modular system whose performance can be tailored to specific application requirements. The overall system concept and the design of the two most important electronic subsystems that support the helmet mounted parts, a new militarized version of the magnetic helmet mounted sight and correspondingly similar helmet display electronics, are discussed in detail. Significant emphasis is given to illustrating how particular design features in the hardware improve overall system performance and support research activities.

Kocian, Dean F.↗
NASA NTRS1992

A discrete Fourier transform for virtual memory machines

An algebraic theory of the Discrete Fourier Transform is developed in great detail. Examination of the details of the theory leads to a computationally efficient fast Fourier transform for the use on computers with virtual memory. Such an algorithm is of great use on modern desktop machines. A FORTRAN coded version of the algorithm is given for the case when the sequence of numbers to be transformed is a power of two.

Galant, David C.↗
NASA NTRS1990

Interfacing laboratory instruments to multiuser, virtual memory computers

Incentives, problems and solutions associated with interfacing laboratory equipment with multiuser, virtual memory computers are presented. The major difficulty concerns how to utilize these computers effectively in a medium sized research group. This entails optimization of hardware interconnections and software to facilitate multiple instrument control, data acquisition and processing. The architecture of the system that was devised, and associated programming and subroutines are described. An example program involving computer controlled hardware for ultrasonic scan imaging is provided to illustrate the operational features.

Generazio, Edward R.↗
NASA NTRS1992

Design of virtual passive controllers for flexible space structures

The properties of virtual passive controllers, i.e., active vibration absorbers, and of the closed-loop systems achievable by means of such compensation are analyzed. It is shown that these controllers introduce additional transmission zeros into the closed-loop system. Therefore, they provide an extra degree of design freedom over that provided by state feedback, which cannot alter the zeros in any way.

Williams, Trevor↗
NASA NTRS1991

Virtual reality applications to automated rendezvous and capture

Virtual Reality (VR) is a rapidly developing Human/Computer Interface (HCI) technology. The evolution of high-speed graphics processors and development of specialized anthropomorphic user interface devices, that more fully involve the human senses, have enabled VR technology. Recently, the maturity of this technology has reached a level where it can be used as a tool in a variety of applications. This paper provides an overview of: VR technology, VR activities at Marshall Space Flight Center (MSFC), applications of VR to Automated Rendezvous and Capture (AR&C), and identifies areas of VR technology that requires further development.

Hale, Joseph↗
NASA NTRS1993

A preliminary empirical evaluation of virtual reality as an instructional medium for visual-spatial tasks

We explored the training potential of Virtual Reality (VR) technology. Thirty-one adults were trained and tested on spatial skills in a VR. They learned a sequence of button and knob responses on a VR console and performed flawlessly on the same console. Half were trained with a rote strategy; the rest used a meaningful strategy. Response times were equivalent for both groups and decreased significantly over five test trials indicating that learning continued on VR tests. The same subjects practiced navigating through a VR building, which had three floors with four rooms on each floor. The dependent measure was the number of rooms traversed on routes that differed from training routes. Many subjects completed tests in the fewest rooms possible. All subjects learned configurational knowledge according to the criterion of taking paths that were significantly shorter than those predicted by a random walk as determined by a Monte Carlo analysis. The results were discussed as a departure point for empirically testing the training potential of VR technology.

Regian, J. Wesley↗
NASA NTRS1993

Determination of balloon gas mass and revised estimates of drag and virtual mass coefficients

In support of the NASA Balloon Program, small-scale balloons were flown with varying lifting gas and total system mass. Instrument packages were developed to measure and record acceleration and temperature data during these tests. Top fitting and instrument payload accelerations were measured from launch to steady state ascent and through ballast drop transients. The development of the small lightweight self-powered Stowaway Special instrument packages is discussed along with mathematical models developed to determine gas mass, drag and virtual mass coefficients.

Robbins, E.↗
NASA NTRS1993

Further development towards a new virtual-pulse time integral methodology for general nonlinear transient thermal analysis

New developments describing the theoretical basis towards an effective virtual-pulse time integral procedure are presented for general nonlinear transient heat transfer problems. To validate the proposed methodology of computation, numerical test examples are given and comparisons are drawn with the implicit second-order accurate Crank-Nicolson technique. The proposed method shows superior or improved accuracy and stability characteristics for the models tested.

Tamma, K. K.↗
NASA NTRS1991

Pictorial communication in virtual and real environments

Papers about the communication between human users and machines in real and synthetic environments are presented. Individual topics addressed include: pictorial communication, distortions in memory for visual displays, cartography and map displays, efficiency of graphical perception, volumetric visualization of 3D data, spatial displays to increase pilot situational awareness, teleoperation of land vehicles, computer graphics system for visualizing spacecraft in orbit, visual display aid for orbital maneuvering, multiaxis control in telemanipulation and vehicle guidance, visual enhancements in pick-and-place tasks, target axis effects under transformed visual-motor mappings, adapting to variable prismatic displacement. Also discussed are: spatial vision within egocentric and exocentric frames of reference, sensory conflict in motion sickness, interactions of form and orientation, perception of geometrical structure from congruence, prediction of three-dimensionality across continuous surfaces, effects of viewpoint in the virtual space of pictures, visual slant underestimation, spatial constraints of stereopsis in video displays, stereoscopic stance perception, paradoxical monocular stereopsis and perspective vergence. (No individual items are abstracted in this volume)

Ellis, Stephen R.↗
NASA NTRS1992

The Virtual Mission - A step-wise approach to large space missions

Attention is given to the Virtual Mission (VM) concept, wherein multiple scientific instruments will be on different platforms, in different orbits, operated from different control centers, at different institutions, and reporting to different user groups. The VM concept enables NASA's science and application users to accomplish their broad science goals with a fleet made up of smaller, more focused spacecraft and to alleviate the difficulties involved with single, large, complex spacecraft. The concept makes possible the stepwise 'go-as-you-pay' extensible approach recommended by Augustine (1990). It enables scientists to mix and match the use of many smaller satellites in novel ways to respond to new scientific ideas and needs.

Hansen, Elaine↗
NASA NTRS1992

Mental rotation - A key to mitigation of motion sickness in the virtual environments?

If mental rotation is important for the reduction of motion sickness and complement performance in virtual environments (VEs), the use of the Howard (1982) mental rotation test battery may identify individuals with lower susceptibility to VE-induced motion sickness and therefore a greater probability of success as VE operators. An apparatus and its associated procedures are currently under development for astronaut microgravity training aimed at reducing motion sickness; it is hypothesized that this system may be of significance to VE testing and training.

Parker, Donald E.↗
NASA NTRS1992

Virtual environment display for a 3D audio room simulation

The development of a virtual environment simulation system integrating a 3D acoustic audio model with an immersive 3D visual scene is discussed. The system complements the acoustic model and is specified to: allow the listener to freely move about the space, a room of manipulable size, shape, and audio character, while interactively relocating the sound sources; reinforce the listener's feeling of telepresence in the acoustical environment with visual and proprioceptive sensations; enhance the audio with the graphic and interactive components, rather than overwhelm or reduce it; and serve as a research testbed and technology transfer demonstration. The hardware/software design of two demonstration systems, one installed and one portable, are discussed through the development of four iterative configurations.

Chapin, William L.↗
NASA NTRS1992

Virtual reality and planetary exploration

NASA-Ames is intensively developing virtual-reality (VR) capabilities that can extend and augment computer-generated and remote spatial environments. VR is envisioned not only as a basis for improving human/machine interactions involved in planetary exploration, but also as a medium for the more widespread sharing of the experience of exploration, thereby broadening the support-base for the lunar and planetary-exploration endeavors. Imagery representative of Mars are being gathered for VR presentation at such terrestrial sites as Antarctica and Death Valley.

Mcgreevy, Michael W.↗
NASA NTRS1993

A two-stage virtual impactor for continuous concentration of particles in an aerosol

A two-stage virtual impactor has been designed and fabricated to concentrate aerosol particles. In this impactor, the minor flow from the first stage of the impactor is introduced into the second stage as the primary flow. The cut-point of the impactor is designed to be about 0.3 micron. The sample aerosol is introduced into the impactor at a flow rate of 8.0 atm-l/min and after the two stages of separation, particles are collected into the minor flow of 0.06 atm-l/min with 84 percent efficiency. The tandem arrangement of the two stages increases the concentration of larger particles by a factor of greater than 100. The small size and the low flow rates make the impactor compatible with the sampling requirements of instruments used for the chemical and physical characterization of particles from low-particle number density aerosols. In particular, the high particle concentration factor of the impactor will make it possible to analyze individual particles in real time from aerosols containing less than 10 particles per cft by the mass spectrometric methods developed in our laboratory.

Sinha, M. P.↗
NASA NTRS1994

System Would Generate Virtual Heads-Up Display

Proposed helmet-mounted electronic display system superimposes full-color alphanumerical and/or graphical information onto observer's visual field. Displayed information projected directly onto observer's retinas, giving observer illusion of full-size computer display in foreground or background. Display stereoscopic, holographic, or in form of virtual image. Used by pilots to view navigational information while looking outside or at instruments, by security officers to view information about critical facilities while looking at visitors, or possibly even stock-exchange facilities to view desktop monitors and overhead displays simultaneously. System includes acousto-optical tunable filter (AOTF), which acts as both spectral filter and spatial light modulator.

Lambert, James L.↗