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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 1,261 records · Page 70
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NASA NTRS1995

Measurements of electromagnetic bias at Ku and C bands

The electromagnetic (EM) bias epsilon is an error present in radar altimetry of the ocean surface due to nonuniform reflection with surface displacement. The electromagnetic bias is defined as the difference in height between the mean reflecting surface and the mean sea surface. A knowledge of the electromagnetic bias is required for reducing errors in mean sea level measurements by satellite radar altimeters. Direct measurements of the EM bias at 14 GHz (Ku band) and 5 GHz (C band) were made from an oil production platform in the Gulf of Mexico over a 6-month period during 1989 and 1990. A total of 1280 hours of usable data was collected. During the experiment the significant wave height (SWH) varied from 0.6 to 3.2 m; the wind speed at 25 m above the surface varied from 0.1 to 14.3 m/s; the Ku band bias varied from -1.0 to -13.8 cm, or from -1.6% to -5.3% of the SWH; and the C band bias varied from -0.4 to -19.9 cm, or from -0.6% to -6.3% of the SWH. The biases has mean values of -3.7% and -3.6% of SWH with standard deviations of the variability about the mean of 0.7% and 1.0% of the SWH for Ku and C bands, respectively. We found a nonlinear relationship between dimensionless bias (bias/SWH) and wind speed at both low and high wind speeds. For wind speeds less than 3-4 m/s but less than 10 m/s, both biases were found to increase linearly with wind speed. For wind speeds greater than 11-12 m/s, the C band bias reaches a maximum. The Ku band bias reaches a maximum and then begins to decrease for wind speeds greater than 9-10 m/s.

Arnold, D. V.↗
NASA NTRS1995

Aerosol effects and corrections in the Halogen Occultation Experiment

The eruptions of Mt. Pinatubo in June 1991 increased stratospheric aerosol loading by a factor of 30, affecting chemistry, radiative transfer, and remote measurements of the stratosphere. The Halogen Occultation Experiment (HALOE) instrument on board Upper Atmosphere Research Satellite (UARS) makes measurements globally for inferring profiles of NO2, H2O, O3, HF, HCl, CH4, NO, and temperature in addition to aerosol extinction at five wavelengths. Understanding and removing the aerosol extinction is essential for obtaining accurate retrievals from the radiometer channels of NO2, H2O and O3 in the lower stratosphere since these measurements are severely affected by contaminant aerosol absorption. If ignored, aerosol absorption in the radiometer measurements is interpreted as additional absorption by the target gas, resulting in anomalously large mixing ratios. To correct the radiometer measurements for aerosol effects, a retrieved aerosol extinction profile is extrapolated to the radiometer wavelengths and then included as continuum attenuation. The sensitivity of the extrapolation to size distribution and composition is small for certain wavelength combinations, reducing the correction uncertainty. The aerosol corrections extend the usable range of profiles retrieved from the radiometer channels to the tropopause with results that agree well with correlative measurements. In situations of heavy aerosol loading, errors due to aerosol in the retrieved mixing ratios are reduced to values of about 15, 25, and 60% in H2O, O3, and NO2, respectively, levels that are much less than the correction magnitude.

Hervig, Mark E.↗
NASA NTRS1995

Candidate site for a robotic lunar observatory: The central peak of Riccioli crater

This paper proposes the central peak of Riccioli crater as the most promising site for an initial lunar observatory. If only one site can be chosen, it should be on the near side, close to the limb, in continual line of sight from the Earth and on or close to the equator. The terrain should be suitable for landings, surface transverses and instrument emplacement. Anticipating an eventual manned observatory and surface exploration base, the site should be geologically diverse and have usable material resources. The central peak of Riccioli, 2.5 deg S and 83 deg W, and adjacent areas, meet these requirements and are recommended for initial telerobotic exploration and instrument emplacement. The floor of Grimaldi is suggested for a sub-site or an alternate site.

Lowman, Paul D., Jr.↗
NASA NTRS1995

The Tully-Fisher relation of the IRAS minisurvey galaxies

We investigated the possible influence on the Tully-Fisher relation of active massive star formation in IRAS galaxies, in order to estimate the contribution of star formation to their near-infrared luminosity. We observed 60 galaxies from the infrared complete so-called IRAS Minisurvey sample in the 21 cm H1 line at Arecibo, determined the near-infrared (H-band) Tully-Fisher relation for the 36 objects in the sample we judged to be usable for this purpose, and compared this relation with that of optically selected normal galaxies. The results show no significant enhancement of the near-infrared luminosities of the IRAS Minisurvey galaxies compared to those of the optically selected normal glaxies. From these results we inferred that in the minisurvey galaxies the average contribution of the active massive star formation to the total near-infrared luminosity is less and that exponential decay times for the starbursts occurring in the Minisurvey galaxies are of the order of 10 Myr. The Tully-Fisher relation shows one exceptional galaxy (IRAS 03565+2139) with an about 25 times higher luminosity than average for its rotational velocity.

Van Driel, W.↗
NASA NTRS1995

The formal verification used for the AAMP5 and AAMP-FV

The main goal of the project was two-fold: First, to investigate the feasibility of formally specifying and verifying a complex commercial microprocessor that was not expressly designed for formal verification. Second, to explore effective ways to transfer the technology to an industrial setting. The choice of the AAMP5 satisfied the first goal since the AAMP5 was not designed for formal verification, but to provide a more than threefold performance improvement while remaining object-code-compatible with the earlier AAMP2, which is used in numerous avionics applications, including the Boeing 737, 747, 757, and 767. To satisfy the technology transfer objective, we had to develop a suitable verification methodology and a formal infrastructure to make the technology usable by practicing engineers. This infrastructure includes techniques for decomposing the microcompressor verification problem into a st of verification conditions that the engineers can formulate and strategies to automate the proof of the verification conditions. The development of the infrastructure was one of the key accomplishments of the project. Most of the infrastructure and methodology are general enough to be reused for other microprocessors, certainly in the verification of another member of the AAMP family. This methodology was used to formally specify the entire microarchitecture and more than half of the instruction set and to verify a core set of eleven AAMP5 instructions representative of several instruction classes. However, the methodology and the formal machinery developed are adequate to cover most of the remaining AAMP5 instructions. Although PVS was the vehicle of the experiment, the methodology is applicable to other sufficiently powerful theorem provers.

Srivas, Mandayam↗
NASA NTRS1990

A comparison of CLIPS- and LISP-based approaches to the development of a real-time expert system

This paper describes an ongoing expert system development effort started in 1988 which is evaluating both CLIPS- and LISP- based approaches. The expert system is being developed to a project schedule and is planned for flight on Space Shuttle Mission SLS-2 in 1992. The expert system will help astronauts do the best possible science for a vestibular physiology experiment already scheduled for that mission. The system gathers and reduces data from the experiment, flags 'interesting' results, and proposes changes in the experiment both to exploit the in-flight observations and to stay within the time allowed by Mission Control for the experiment. These tasks must all be performed in real time. Two Apple Macintosh computers are used. The CLIPS- and LISP- based environments are layered above the Macintosh computer Operating System. The 'CLIPS-based' environment includes CLIPS and HyperCard. The LlSP-based environment includes Common LISP, Parmenides (a frame system), and FRuleKit (a rule system). Important evaluation factors include ease of programming, performance against real-time requirements, usability by an astronaut, robustness, and ease of maintenance. Current results on the factors of ease of programming, performance against real-time requirements, and ease of maintenance are discussed.

Frainier, R.↗
NASA NTRS1995

The development of the Final Approach Spacing Tool (FAST): A cooperative controller-engineer design approach

Historically, the development of advanced automation for air traffic control in the United States has excluded the input of the air traffic controller until the need of the development process. In contrast, the development of the Final Approach Spacing Tool (FAST), for the terminal area controller, has incorporated the end-user in early, iterative testing. This paper describes a cooperative between the controller and the developer to create a tool which incorporates the complexity of the air traffic controller's job. This approach to software development has enhanced the usability of FAST and has helped smooth the introduction of FAST into the operational environment.

Lee, Katharine K.↗
NASA NTRS1995

An adaptable product for material processing and life science missions

The Experiment Control System II (ECS-II) is designed to make available to the microgravity research community the same tools and mode of automated experimentation that their ground-based counterparts have enjoyed for the last two decades. The design goal was accomplished by combining commercial automation tools familiar to the experimenter community with system control components that interface with the on-orbit platform in a distributed architecture. The architecture insulates the tools necessary for managing a payload. By using commercial software and hardware components whenever possible, development costs were greatly reduced when compared to traditional space development projects. Using commercial-off-the-shelf (COTS) components also improved the usability documentation, and reducing the need for training of the system by providing familiar user interfaces, providing a wealth of readily available documentation, and reducing the need for training on system-specific details. The modularity of the distributed architecture makes it very amenable for modification to different on-orbit experiments requiring robotics-based automation.

Wassick, Gregory↗
NASA NTRS1994

Use of Video Analysis System for Working Posture Evaluations

In a work environment, it is important to identify and quantify the relationship among work activities, working posture, and workplace design. Working posture may impact the physical comfort and well-being of individuals, as well as performance. The Posture Video Analysis Tool (PVAT) is an interactive menu and button driven software prototype written in Supercard (trademark). Human Factors analysts are provided with a predefined set of options typically associated with postural assessments and human performance issues. Once options have been selected, the program is used to evaluate working posture and dynamic tasks from video footage. PVAT has been used to evaluate postures from Orbiter missions, as well as from experimental testing of prototype glove box designs. PVAT can be used for video analysis in a number of industries, with little or no modification. It can contribute to various aspects of workplace design such as training, task allocations, procedural analyses, and hardware usability evaluations. The major advantage of the video analysis approach is the ability to gather data, non-intrusively, in restricted-access environments, such as emergency and operation rooms, contaminated areas, and control rooms. Video analysis also provides the opportunity to conduct preliminary evaluations of existing work areas.

McKay, Timothy D.↗
NASA NTRS1994

Application Reuse Library for Software, Requirements, and Guidelines

Better designs are needed for expert systems and other operations automation software, for more reliable, usable and effective human support. A prototype computer-aided Application Reuse Library shows feasibility of supporting concurrent development and improvement of advanced software by users, analysts, software developers, and human-computer interaction experts. Such a library expedites development of quality software, by providing working, documented examples, which support understanding, modification and reuse of requirements as well as code. It explicitly documents and implicitly embodies design guidelines, standards and conventions. The Application Reuse Library provides application modules with Demo-and-Tester elements. Developers and users can evaluate applicability of a library module and test modifications, by running it interactively. Sub-modules provide application code and displays and controls. The library supports software modification and reuse, by providing alternative versions of application and display functionality. Information about human support and display requirements is provided, so that modifications will conform to guidelines. The library supports entry of new application modules from developers throughout an organization. Example library modules include a timer, some buttons and special fonts, and a real-time data interface program. The library prototype is implemented in the object-oriented G2 environment for developing real-time expert systems.

Malin, Jane T.↗
NASA NTRS1994

A prototype supervised intelligent robot for helping astronauts

The development status is described of a prototype supervised intelligent robot for space application for purposes of (1) helping the crew of a spacecraft such as the Space Station with various tasks such as holding objects and retrieving/replacing tools and other objects from/into storage, and for purposes of (2) retrieving detached objects, such as equipment or crew, that have become separated from their spacecraft. In addition to this set of tasks in this low Earth orbiting spacecraft environment, it is argued that certain aspects of the technology can be viewed as generic in approach, thereby offering insight into intelligent robots for other tasks and environments. Also described are characterization results on the usable reduced gravity environment in an aircraft flying parabolas (to simulate weightlessness) and results on hardware performance there. These results show it is feasible to use that environment for evaluative testing of dexterous grasping based on real-time visual sensing of freely rotating and translating objects.

Erickson, J. D.↗
NASA NTRS1995

Multithreaded Model for Dynamic Load Balancing Parallel Adaptive PDE Computations

We present a multithreaded model for the dynamic load-balancing of numerical, adaptive computations required for the solution of Partial Differential Equations (PDE's) on multiprocessors. Multithreading is used as a means of exploring concurrency in the processor level in order to tolerate synchronization costs inherent to traditional (non-threaded) parallel adaptive PDE solvers. Our preliminary analysis for parallel, adaptive PDE solvers indicates that multithreading can be used an a mechanism to mask overheads required for the dynamic balancing of processor workloads with computations required for the actual numerical solution of the PDE's. Also, multithreading can simplify the implementation of dynamic load-balancing algorithms, a task that is very difficult for traditional data parallel adaptive PDE computations. Unfortunately, multithreading does not always simplify program complexity, often makes code re-usability not an easy task, and increases software complexity.

Chrisochoides, Nikos↗
NASA NTRS1996

Magnetic levitation systems for future aeronautics and space research and missions

The objectives, advantages, and research needs for several applications of superconducting magnetic levitation to aerodynamics research, testing, and space-launch are discussed. Applications include very large-scale magnetic balance and suspension systems for high alpha testing, support interference-free testing of slender hypersonic propulsion/airframe integrated vehicles, and hypersonic maglev. Current practice and concepts are outlined as part of a unified effort in high magnetic fields R&D within NASA. Recent advances in the design and construction of the proposed ground-based Holloman test track (rocket sled) that uses magnetic levitation are presented. It is protected that ground speeds of up to Mach 8 to 11 at sea-level are possible with such a system. This capability may enable supersonic combustor tests as well as ramjet-to-scramjet transition simulation to be performed in clean air. Finally a novel space launch concept (Maglifter) which uses magnetic levitation and propulsion for a re-usable 'first stage' and rocket or air-breathing combined-cycle propulsion for its second stage is discussed in detail. Performance of this concept is compared with conventional advanced launch systems and a preliminary concept for a subscale system demonstration is presented.

Blankson, Isaiah M.↗
NASA NTRS1996

Communications satellites in the national and global health care information infrastructure: their role, impact, and issues

Health care services delivered from a distance, known collectively as telemedicine, are being increasingly demonstrated on various transmission media. Telemedicine activities have included diagnosis by a doctor at a remote location, emergency and disaster medical assistance, medical education, and medical informatics. The ability of communications satellites to offer communication channels and bandwidth on demand, connectivity to mobile, remote and under served regions, and global access will afford them a critical role for telemedicine applications within the National and Global Information Infrastructure (NII/GII). The importance that communications satellites will have in telemedicine applications within the NII/GII the differences in requirements for NII vs. GII, the major issues such as interoperability, confidentiality, quality, availability, and costs, and preliminary conclusions for future usability based on the review of several recent trails at national and global levels are presented.

Zuzek, J. E.↗
NASA NTRS1996

Studies of Vestibular Neurons in Normal, Hyper- and Hypogravity

During the past year, pre-, in- and postflight studies were conducted in association with the Axon project for Bion 10 (Cosmos 2229). Recordings were made during pre- and postflight studies, from 118 horizontal semicircular canal afferents and 27 vestibular nucleus neurons in 7 rhesus monkeys; 137 pulse rotation protocols alone were executed (548 acceleration and deceleration responses were curve fit). Usable data was obtained from 127 horizontal afferents concerning their spontaneous discharge. Curve fits and analysis was made of sinusoidal and sum of sinusoidal responses from 42 and 35 horizontal afferents, respectively. Also recordings were made from neurons inflight from the two flight animals. The mean spontaneous rate varied from 128 spikes/sec. during preflight to 92 spikes/sec during postflight (day 5) - a change of 28%. In direct contrast to the results of Cosmos 2044, the best fitted neural adaptation operator (k) and the gain of the pulse response were decreased during post flight when compared to preflight. Surprisingly, the best fitted gain and k values for the sum of sines were slightly elevated during post flight tests. The gain and phase of single sine responses were compared for pre- and post flight tests and compared to a larger population of afferents. In contrast to Cosmos 2044 results where on the first day of post flight testing the gains of the best fitted sine response were skewed toward the higher values of the Miles and Braitman distribution, the gain of the best fitted sine responses during the first day of post flight testing (day 2) during Cosmos 2229 were exactly on the mode of the Miles and Braitman distribution. Thus, at least for the periodic stimuli, (pulses and sine waves) we found no change in gain and neural adaptation during post flight testing following Cosmos 2229. This conclusion is different from the one derived following the Cosmos 2044 flight. Cosmos flight 2229 differed from Cosmos flight 2044 in several significant ways: For example, during preflight, (1) The animals preflight training was different (less well trained on the gaze task) and (2) the animals were exposed to more experimental manipulations (surgical and rotational). Inflight, (1) the animals were required to make a pointing gesture (motor response) in association with eye movements to obtain reward, (2) the inflight diet was different (more balanced), (3) the feeder for one of the animals clogged following 9 days of flight resulting in evident dehydration and probably less head motion exposure in that monkey and (4) there was limited video taping of the monkeys in space. During postflight, (1) we were unable to test the flight animals until 26 hours postflight as compared to 14.5 hours during Cosmos 2044, (2) the animals received significantly more exposure to motion stimuli during postflight testing than during Cosmos 2044. These differences in the vestibular environment will require analysis of several parameters other than just neural and eye movement responses. For example, computer programs will have to be written and used to recover and quantify the number of head movements made by each animal during flight. This activity is critical to the production of neural adaptation and increased gain.

Correia, Manning J.↗
NASA NTRS1996

Development of Methodologies for the Estimation of Thermal Properties Associated with Aerospace Vehicles

A thermal stress analysis is an important aspect in the design of aerospace structures and vehicles such as the High Speed Civil Transport (HSCT) at the National Aeronautics and Space Administration Langley Research Center (NASA-LaRC). These structures are complex and are often composed of numerous components fabricated from a variety of different materials. The thermal loads on these structures induce temperature variations within the structure, which in turn result in the development of thermal stresses. Therefore, a thermal stress analysis requires knowledge of the temperature distributions within the structures which consequently necessitates the need for accurate knowledge of the thermal properties, boundary conditions and thermal interface conditions associated with the structural materials. The goal of this proposed multi-year research effort was to develop estimation methodologies for the determination of the thermal properties and interface conditions associated with aerospace vehicles. Specific objectives focused on the development and implementation of optimal experimental design strategies and methodologies for the estimation of thermal properties associated with simple composite and honeycomb structures. The strategy used in this multi-year research effort was to first develop methodologies for relatively simple systems and then systematically modify these methodologies to analyze complex structures. This can be thought of as a building block approach. This strategy was intended to promote maximum usability of the resulting estimation procedure by NASA-LARC researchers through the design of in-house experimentation procedures and through the use of an existing general purpose finite element software.

Scott, Elaine P.↗
NASA NTRS1996

Performance Analysis of Two Early NACA High Speed Propellers with Application to Civil Tiltrotor Configurations

The helicopter industry is vigorously pursuing development of civil tiltrotors. One key to efficient high speed performance of this rotorcraft is prop-rotor performance. Of equal, if not greater, importance is assurance that the flight envelope is free of aeroelastic instabilities well beyond currently envisioned cuise speeds. This later condition requires study at helical tip Match numbers well in excess of 1.0. Two 1940's 'supersonic' propeller experiments conducted by NACA have provided an immensely valuable data bank with which to study prop-rotor behavior at transonic and supersonic helical tip Mach numbers. Very accurate 'blades alone' data were obtained by using nearly an infinite hub. Tabulated data were recreated from the many thrust and power figures and are included in two Appendices to this report. This data set is exceptionally well suited to re-evaluating classical blade element theories as well as evolving computational fluid dynamic (CFD) analyses. A limited comparison of one propeller's experimental results to a modem rotorcraft CFD code is made. This code, referred to as TURNS, gives very encouraging results. Detailed analysis of the performance data from both propellers is provided in Appendix A. This appendix quantifies the minimum power required to produce usable prop-rotor thrust. The dependence of minimum profile power on Reynolds number is quantified. First order compressibility power losses are quantified as well and a first approximation to design air-foil thickness ratio to avoid compressibility losses is provided. Appendix A's results are applied to study high speed civil tiltrotor cruise performance. Predicted tiltrotor performance is compared to two turboprop commercial transports. The comparison shows that there is no fundamental aerodynamic reason why the rotorcraft industry could not develop civil tiltrotor aircraft which have competitive cruise performance with today's regional, turboprop airlines. Recommendations for future study that will insure efficient prop-rotor performance to well beyond 400 knots are given.

Harris, Franklin D.↗
NASA NTRS1996

A Software Quality Model and Metrics for Risk Assessment

A software quality model and its associated attributes are defined and used as the model for the basis for a discussion on risk. Specific quality goals and attributes are selected based on their importance to a software development project and their ability to be quantified. Risks that can be determined by the model's metrics are identified. A core set of metrics relating to the software development process and its products is defined. Measurements for each metric and their usability and applicability are discussed.

L Hyatt↗