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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 NTRS1994

Generic mission planning and scheduling: The AXAF solution

During SpaceOps 92 the idea of generic mission planning concepts for space astronomy missions, that could be applied to future missions in order to simplify software development, was introduced. It was proposed that mission planning systems could be decomposed into functional elements that could be standardized and then organized into optimal functional flows for each individual mission. In addition, it was further suggested that these flows themselves could be reduced to a small set of possibilities by describing them in terms of generic mission type, such as manned, unmanned, high orbit, low orbit, etc. The Advanced X-ray Astrophysics Facility (AXAF), planned for launch in the latter part of '98, represents the first application of this idea on an unmanned mission. This paper examines the AXAF Mission Planning and Scheduling concept in light of the generic system theory. Each functional element is evaluated according to AXAF characteristics and requirements and then compared to its generic counterpart. Functional flow considerations are then derived from the overall AXAF mission planning concept to determine the viability and sensitivity of the generic flow to actual requirements. The results of this analysis are then used to update the generic system concept and to define the level of commonality and core system components that are practical to achieve across multiple missions.

Guffin, O. T.↗
NASA NTRS1994

Concept verification of three dimensional free motion simulator for space robot

In the development of automatic assembling technologies for space structures, it is an indispensable matter to investigate and simulate the movements of robot satellites concerned with mission operation. The movement investigation and simulation on the ground will be effectively realized by a free motion simulator. Various types of ground systems for simulating free motion have been proposed and utilized. Some of these methods are a neutral buoyancy system, an air or magnetic suspension system, a passive suspension balance system, and a free flying aircraft or drop tower system. In addition, systems can be simulated by computers using an analytical model. Each free motion simulation method has limitations and well known problems, specifically, disturbance by water viscosity, limited number of degrees-of-freedom, complex dynamics induced by the attachment of the simulation system, short experiment time, and the lack of high speed super-computer simulation systems, respectively. The basic idea presented here is to realize 3-dimensional free motion. This is achieved by combining a spherical air bearing, a cylindrical air bearing, and a flat air bearing. A conventional air bearing system has difficulty realizing free vertical motion suspension. The idea of free vertical suspension is that a cylindrical air bearing and counter balance weight realize vertical free motion. This paper presents a design concept, configuration, and basic performance characteristics of an innovative free motion simulator. A prototype simulator verifies the feasibility of 3-dimensional free motion simulation.

Okamoto, Osamu↗
NASA NTRS1994

How to fly an aircraft with control theory and splines

When trying to fly an aircraft as smoothly as possible it is a good idea to use the derivatives of the pilot command instead of using the actual control. This idea was implemented with splines and control theory, in a system that tries to model an aircraft. Computer calculations in Matlab show that it is impossible to receive enough smooth control signals by this way. This is due to the fact that the splines not only try to approximate the test function, but also its derivatives. A perfect traction is received but we have to pay in very peaky control signals and accelerations.

Karlsson, Anders↗
NASA NTRS1995

Computerized Design and Generation of Low-Noise Gears with Localized Bearing Contact

The results of research projects directed at the reduction of noise caused by misalignment of the following gear drives: double-circular arc helical gears, modified involute helical gears, face-milled spiral bevel gears, and face-milled formate cut hypoid gears are presented. Misalignment in these types of gear drives causes periodic, almost linear discontinuous functions of transmission errors. The period of such functions is the cycle of meshing when one pair of teeth is changed for the next. Due to the discontinuity of such functions of transmission errors high vibration and noise are inevitable. A predesigned parabolic function of transmission errors that is able to absorb linear discontinuous functions of transmission errors and change the resulting function of transmission errors into a continuous one is proposed. The proposed idea was successfully tested using spiral bevel gears and the noise was reduced a substantial amount in comparison with the existing design. The idea of a predesigned parabolic function is applied for the reduction of noise of helical and hypoid gears. The effectiveness of the proposed approach has been investigated by developed TCA (tooth contact analysis) programs. The bearing contact for the mentioned gears is localized. Conditions that avoid edge contact for the gear drives have been determined. Manufacturing of helical gears with new topology by hobs and grinding worms has been investigated.

Litvin, Faydor L.↗
NASA NTRS1994

Is there a role for a test controller in the development of new ATC equipment?

Earl Wiener points out that human factors problems fixed during the R & D stage are paid for once. When they are not fixed during R & D, they are then paid for every day. How users are involved in the R & D process to assist in developing equipment is a critical issue. Effective involvement can produce real improvements. Ineffective involvement can produce inefficient kludges or systems that are actually dangerous. The underlying problem is the management of information and ideas. To develop a really generative system a great deal would have to change in the way that the FAA innovates. Use of test controllers would solve only some of the problems. For instance, we have cockpit resource management now for pilots; we may have it soon for controllers. But the management of ideas in the innovation process also needs intellectual resource management. Simply involving users is not enough. Brought in at the wrong point in the development process, users can block or compromise innovation. User involvement must be carefully considered. A test controller may be one solution to this problem. It might be necessary to have several kinds of test controllers (en route versus TRACON, for instance). No doubt further problems would surface in getting test controllers into operation. I would recommend that the FAA engage in a series of case studies of controller involvement in the innovation process. A systematic comparison of effective and ineffective cases would do much to clarify what we ought to do in the future. Unfortunately, I have been unable to find any cases where test controllers have been used. Perhaps we need to create some, to see how they work.

Westrum, Ron↗
NASA NTRS1994

A volume-limited ROSAT survey of extreme ultraviolet emission from all nondegenerate stars within 10 parsecs

We report the results of a volume-limited ROSAT Wide Field Camera (WFC) survey of all nondegenerate stars within 10 pc. Of the 220 known star systems within 10 pc, we find that 41 are positive detections in at least one of the two WFC filter bandpasses (S1 and S2), while we consider another 14 to be marginal detections. We compute X-ray luminosities for the WFC detections using Einstein Imaging Proportional Counter (IPC) data, and these IPC luminosities are discussed along with the WFC luminosities throughout the paper for purposes of comparison. Extreme ultraviolet (EUV) luminosity functions are computed for single stars of different spectral types using both S1 and S2 luminosities, and these luminosity functions are compared with X-ray luminosity functions derived by previous authors using IPC data. We also analyze the S1 and S2 luminosity functions of the binary stars within 10 pc. We find that most stars in binary systems do not emit EUV radiation at levels different from those of single stars, but there may be a few EUV-luminous multiple-star systems which emit excess EUV radiation due to some effect of binarity. In general, the ratio of X-ray luminosity to EUV luminosity increases with increasing coronal emission, suggesting that coronally active stars have higher coronal temperatures. We find that our S1, S2, and IPC luminosities are well correlated with rotational velocity, and we compare activity-rotation relations determined using these different luminosities. Late M stars are found to be significantly less luminous in the EUV than other late-type stars. The most natural explanation for this results is the concept of coronal saturation -- the idea that late-type stars can emit only a limited fraction of their total luminosity in X-ray and EUV radiation, which means stars with very low bolometric luminosities must have relatively low X-ray and EUV luminosities as well. The maximum level of coronal emission from stars with earlier spectral types is studied also. To understand the saturation levels for these stars, we have compiled a large number of IPC luminosities for stars with a wide variety of spectral types and luminosity classes. We show quantitatively that if the Sun were completely covered with X-ray-emitting coronal loops, it would be near the saturation limit implied by this compilation, supporting the idea that stars near upper limits in coronal activity are completely covered with active regions.

Wood, Brian E.↗
NASA NTRS1994

Deep cumulonimbus cloud systems in the tropics with and without lightning

The thunderstorm frequency over the oceans during the Global Atmospheric Research Program Atlantic Tropical Experiment is quantified by examination of over 20,000 surface hourly observations from research ships. The overall thunderstorm frequency is one thunderstorm day per ship per month. There were many examples of intense mesoscale systems, such as squall lines, passing over the ships, extending to 13-17 km in altitude, but that nevertheless produce few reports of lightning. This reinforces the idea, based on data from other tropical ocean regions and from global satellite data, that in spite of the ubiquitous 'hot towers' over tropical oceans, marine cumulonimbus produce little lightning. Climatological data from the monsoon regions of the Tropics are analyzed to reveal that during periods of onshore flow and heavy rainfall the oceanic regime of high rainfall but little lightning moves onshore. A rain-thunderstorm ratio is defined and used to characterize convective rainfall regimes as continental (relatively little) or maritime (relatively great) rainfall compared to the number of thunderstorm days. In regions such as West Africa and south Asia, the seasonal rainfall peak is actually accompanied by a thunderstorm minimum. It is further suggested that the data support the idea, not original here, that vertical velocities in oceanic cumulonimbus clouds tend to be low compared with continental clouds. It is hypothesized that most oceanic storms have updrafts weaker than a posssible threshold value, below which the supercooled liquid water, large ice particles, and ice-ice collisions are not present in the mixed-phase region in sufficient concentrations for electrification leading to lightning.

Zipser, Edward J.↗
NASA NTRS1994

Generic astronomy mission planning and scheduling: The AXAF solution

During SpaceOps 92 the idea of generic mission planning concepts for space astronomy missions, that could be applied to future missions in order to simplify software development, was introduced. It was proposed that mission planning systems could be decomposed into functional elements that could be standardized and then organized into optimal functional flows for each individual mission. In addition, it was further suggested that these flows themselves could be reduced to a small set of possibilities by describing them in terms of generic mission type, such as manned, unmanned, high orbit, low orbit, etc. The Advanced X-ray Astrophysics Facility (AXAF), planned for launch in the latter part of 1998, represents the first application of this idea on an unmanned mission. This paper examines the AXAF Mission Planning and Scheduling concept in light of the generic system theory. Each functional element is evaluated according to AXAF characteristics and requirements and then compared to its generic counterpart. Functional flow considerations are then derived from the overall AXAF mission planning concept to determine the viability and sensitivity of the generic flow to actual requirements. The results of this analysis are then used to update the generic system concept and to define the level of commonality and core system components that are practical to achieve across multiple missions.

Guffin, O. T.↗
NASA NTRS1995

Report of results of benchmarking survey of central heating operations at NASA centers and various corporations

In recent years, Total Quality Management has swept across the country. Many companies and the Government have started looking at every aspect on how business is done and how money is spent. The idea or goal is to provide a service that is better, faster and cheaper. The first step in this process is to document or measure the process or operation as it stands now. For Lewis Research Center, this report is the first step in the analysis of heating plant operations. This report establishes the original benchmark that can be referred to in the future. The report also provides a comparison to other organization's heating plants to help in the brainstorming of new ideas. The next step is to propose and implement changes that would meet the goals as mentioned above. After the changes have been implemented the measuring process starts over again. This provides for a continuous improvement process.

Hoffman, Thomas R.↗
NASA NTRS1994

Weapons to widgets: Organic systems and public policy for tech transfer

Large cuts in defense spending cause serious repercussions throughout the American economy. One means to counter the negative effects of defense reductions is to redirect federal dollars to temporarily prop up defense industries and, over the longer-term, stimulate growth of new nondefense industries. The creation of non-defense products and industries by channeling ideas from public laboratories into the private sector manufacturing facilities, known as technology transfer, is being undertaken in a massive program that has high visibility, large amounts of money, and broad federal agency involvement. How effectively federal money can be directed toward stimulating the creation of non-defense products will define the strength of the economy, (i.e., tax base, employment level, trade balance, capital investments, etc.), over the next decade. Key functions of the tech transfer process are technology and market assessment, capital formation, manufacturing feasibility, sales and distribution, and business organization creation. Those, however, are not functions typically associated with the federal government. Is the government prepared to provide leadership in those areas? This paper suggests organic systems theory as a means to structure the public sector's actions to provide leadership in functional areas normally outside their scope of expertise. By applying new ideas in organization theory, can we design government action to efficiently and effectively transfer technologies?

Cargo, Russell A.↗
NASA NTRS1995

The CAVE (TM) automatic virtual environment: Characteristics and applications

Virtual reality may best be defined as the wide-field presentation of computer-generated, multi-sensory information that tracks a user in real time. In addition to the more well-known modes of virtual reality -- head-mounted displays and boom-mounted displays -- the Electronic Visualization Laboratory at the University of Illinois at Chicago recently introduced a third mode: a room constructed from large screens on which the graphics are projected on to three walls and the floor. The CAVE is a multi-person, room sized, high resolution, 3D video and audio environment. Graphics are rear projected in stereo onto three walls and the floor, and viewed with stereo glasses. As a viewer wearing a location sensor moves within its display boundaries, the correct perspective and stereo projections of the environment are updated, and the image moves with and surrounds the viewer. The other viewers in the CAVE are like passengers in a bus, along for the ride. 'CAVE,' the name selected for the virtual reality theater, is both a recursive acronym (Cave Automatic Virtual Environment) and a reference to 'The Simile of the Cave' found in Plato's 'Republic,' in which the philosopher explores the ideas of perception, reality, and illusion. Plato used the analogy of a person facing the back of a cave alive with shadows that are his/her only basis for ideas of what real objects are. Rather than having evolved from video games or flight simulation, the CAVE has its motivation rooted in scientific visualization and the SIGGRAPH 92 Showcase effort. The CAVE was designed to be a useful tool for scientific visualization. The Showcase event was an experiment; the Showcase chair and committee advocated an environment for computational scientists to interactively present their research at a major professional conference in a one-to-many format on high-end workstations attached to large projection screens. The CAVE was developed as a 'virtual reality theater' with scientific content and projection that met the criteria of Showcase.

Kenyon, Robert V.↗
NASA NTRS1996

Orbiter Flight Deck Redesign (A Physical Layout for a Futuristic Flight Deck)

The purpose of this summer project was to develop a set of schematic drawings for redesign of the Space Shuttle flight deck from which three dimensional computer drawings can be built and viewed in a virtual environment. In order to achieve this goal, first recommendations for overall redesign of Space Shuttle previously made by experts in the field were reviewed and relevant information was extracted and delineated. Original drawings of the Space Shuttle made by Rockwell were obtained and carefully examined. In order to implement and assess any modifications in terms of space saving parameters, it was determined that the drawings alone could not achieve this objective. As a complement, physical measurements of the mockup of Space Shuttle flight deck were made and the information was categorized and properly labeled on the original drawings. Then, spacesaving redesign ideas, as motivated by expert recommendations on such things as information display panel upgrade by technologically advanced flat display units, were implemented. Next, the redesign ideas were executed on the Forward flight deck, Overhead Console, Right and Left Console, and Center Console. A new 3-D computer drawing of this was developed by modifying the existing drawing on the in-house developed software (PLAID). Finally, the drawing was transported to a Virtual Environment and observed.

Khorsandi, Mehrzad↗
NASA NTRS1996

Wavelet Sparse Approximate Inverse Preconditioners

There is an increasing interest in using sparse approximate inverses as preconditioners for Krylov subspace iterative methods. Recent studies of Grote and Huckle and Chow and Saad also show that sparse approximate inverse preconditioner can be effective for a variety of matrices, e.g. Harwell-Boeing collections. Nonetheless a drawback is that it requires rapid decay of the inverse entries so that sparse approximate inverse is possible. However, for the class of matrices that, come from elliptic PDE problems, this assumption may not necessarily hold. Our main idea is to look for a basis, other than the standard one, such that a sparse representation of the inverse is feasible. A crucial observation is that the kind of matrices we are interested in typically have a piecewise smooth inverse. We exploit this fact, by applying wavelet techniques to construct a better sparse approximate inverse in the wavelet basis. We shall justify theoretically and numerically that our approach is effective for matrices with smooth inverse. We emphasize that in this paper we have only presented the idea of wavelet approximate inverses and demonstrated its potential but have not yet developed a highly refined and efficient algorithm.

Chan, Tony F.↗
NASA NTRS1996

A dynamic subgrid-scale model for LES of the G-equation

Turbulent combustion is a difficult subject as it must deal with all of the issues found in both turbulence and combustion. (We consider only premixed flames in this paper, but some of the ideas can be applied to the non-premixed case.) As in many other fields, there are two limiting cases that are easier to deal with than the general case. These are the situations in which the chemical time scale is either much shorter or much longer than the time scale associated with the turbulence. We deal with the former case. In this limit, the flame is thin compared to the turbulence length scales and can be idealized as an infinitely thin sheet. This is commonly called the flamelet regime; it has been the subject of many papers and the basis for many models (see, e.g., Linan & Williams 1993). In the flamelet model, the local flame structure is assumed to be identical to the laminar flame structure; thus the flame propagates normal to itself at the laminar flame speed, S(sub L). This allows the use of simple approximations. For example, one expects the rate of consumption of fuel to be proportional to the area of the flame surface. This idea allowed Damkohler (1940) to propose that the wrinkled flame could be replaced by a smooth one which travels at the turbulent flame speed, S(sub T), defined by S(sub T)/S(sub L) = A(sub L) /A(sub P) where A(sub L) is the total flame surface area and AP is the area projected onto the mean direction of propagation. This relation can be expected to be valid when the flame structure is modified only slightly by the turbulence. More recent approaches have attempted to relate the turbulent flame speed to turbulence intensity, u(sub '), which presumably, characterizes the wrinkling of the flame.

Bourlioux, A.↗
NASA NTRS1994

The Grand Tour via Geodesic Interpolation of 2-frames

Grand tours are a class of methods for visualizing multivariate data, or any finite set of points in n-space. The idea is to create an animation of data projections by moving a 2-dimensional projection plane through n-space. The path of planes used in the animation is chosen so that it becomes dense, that is, it comes arbitrarily close to any plane. One of the original inspirations for the grand tour was the experience of trying to comprehend an abstract sculpture in a museum. One tends to walk around the sculpture, viewing it from many different angles. A useful class of grand tours is based on the idea of continuously interpolating an infinite sequence of randomly chosen planes. Visiting randomly (more precisely: uniformly) distributed planes guarantees denseness of the interpolating path. In computer implementations, 2-dimensional orthogonal projections are specified by two 1-dimensional projections which map to the horizontal and vertical screen dimensions, respectively. Hence, a grand tour is specified by a path of pairs of orthonormal projection vectors. This paper describes an interpolation scheme for smoothly connecting two pairs of orthonormal vectors, and thus for constructing interpolating grand tours. The scheme is optimal in the sense that connecting paths are geodesics in a natural Riemannian geometry.

Asimov, Daniel↗
NASA NTRS1996

Bioprocessing in Microgravity: Applications of Continuous Flow Electrophoresis to Rat Anterior Pituitary Particles

In this report we describe the results of a continuous flow electrophoresis (CFE) experiment done on STS-65 in which we tested the idea that intracellular growth hormone (GH) particles contained in a cell lysate prepared from cultured rat anterior pituitary cells in microgravity might have different electrophoretic mobilities from those in a synchronous ground control cell lysate. Collectively, the results suggested that CFE processing in microgravity was better than on earth; more samples could be processed at a time (6 x) and more variant forms of GH molecules could be resolved as well. We had also hoped to carry out a pituitary cell CFE experiment, but failure of the hardware required that the actual cell electrophoresis trials be done on earth shortly after Shuttle landing. Data from these experiments showed that space-flown cells possessed a higher electrophoretic mobility than ground control cells, thereby offering evidence for the idea that exposure of cultured cells to microgravity can change their net surface charge-density especially when the cells are fed. Collectively, the results from this pituitary cell experiment document the advantage of using coupled cell culture and CFE techniques in the microgravity environment.

Hymer, W. C.↗
NASA NTRS1992

Toward Agent Programs with Circuit Semantics

New ideas are presented for computing and organizing actions for autonomous agents in dynamic environments-environments in which the agent's current situation cannot always be accurately discerned and in which the effects of actions cannot always be reliably predicted. The notion of 'circuit semantics' for programs based on 'teleo-reactive trees' is introduced. Program execution builds a combinational circuit which receives sensory inputs and controls actions. These formalisms embody a high degree of inherent conditionality and thus yield programs that are suitably reactive to their environments. At the same time, the actions computed by the programs are guided by the overall goals of the agent. The paper also speculates about how programs using these ideas could be automatically generated by artificial intelligence planning systems and adapted by learning methods.

ELECTRICAL CIRCUITS↗
NASA NTRS1996

Distant Operational Care Centre: Design Project Report

The goal of this project is to outline the design of the Distant Operational Care Centre (DOCC), a modular medical facility to maintain human health and performance in space, that is adaptable to a range of remote human habitats. The purpose of this project is to outline a design, not to go into a complete technical specification of a medical facility for space. This project involves a process to produce a concise set of requirements, addressing the fundamental problems and issues regarding all aspects of a space medical facility for the future. The ideas presented here are at a high level, based on existing, researched, and hypothetical technologies. Given the long development times for space exploration, the outlined concepts from this project embodies a collection of identified problems, and corresponding proposed solutions and ideas, ready to contribute to future space exploration efforts. In order to provide a solid extrapolation and speculation in the context of the future of space medicine, the extent of this project's vision is roughly within the next two decades. The Distant Operational Care Centre (DOCC) is a modular medical facility for space. That is, its function is to maintain human health and performance in space environments, through prevention, diagnosis, and treatment. Furthermore, the DOCC must be adaptable to meet the environmental requirements of different remote human habitats, and support a high quality of human performance. To meet a diverse range of remote human habitats, the DOCC concentrates on a core medical capability that can then be adapted. Adaptation would make use of the DOCC's functional modularity, providing the ability to replace, add, and modify core functions of the DOCC by updating hardware, operations, and procedures. Some of the challenges to be addressed by this project include what constitutes the core medical capability in terms of hardware, operations, and procedures, and how DOCC can be adapted to different remote habitats.

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