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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 541 records · Page 30

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NASA NTRS1986

Personal Cooling System

Cool Head, a personal cooling system for use in heat stress occupations, is a spinoff of a channeled cooling garment for space wear. It is portable and includes a heat exchanger, control display unit, liquid reservoir and temperature control unit. The user can eliminate 40 to 60 percent of his body's heat storage and lower heart rate by 50 to 80 beats a minute. The system is used by the Army, Navy, crop dusting pilots, heavy equipment operators and auto racing drivers and is marketed by Life Enhancement Technologies, LLC. Further applications are under consideration.

Source record↗

NASA NTRS2003

Experiments with Test Case Generation and Runtime Analysis

Software testing is typically an ad hoc process where human testers manually write many test inputs and expected test results, perhaps automating their execution in a regression suite. This process is cumbersome and costly. This paper reports preliminary results on an approach to further automate this process. The approach consists of combining automated test case generation based on systematically exploring the program's input domain, with runtime analysis, where execution traces are monitored and verified against temporal logic specifications, or analyzed using advanced algorithms for detecting concurrency errors such as data races and deadlocks. The approach suggests to generate specifications dynamically per input instance rather than statically once-and-for-all. The paper describes experiments with variants of this approach in the context of two examples, a planetary rover controller and a space craft fault protection system.

Artho, Cyrille↗

NASA NTRS2003

Passive Ball Capture Joint

A passive ball capture joint has a sleeve with a plurality of bores distributed about a circumference thereof and formed therethrough at an acute angle relative to the sleeve's longitudinal axis. A spring-loaded retainer is slidingly fitted in each bore and is biased such that, if allowed, will extend at least partially into the sleeve to retain a ball therein. A ring, rotatably mounted about the bores, has an interior wall defining a plurality of shaped races that bear against the spring-loaded retainers. A mechanized rotational force producer is coupled to the ring. The ring can be rotated from a first position (that presses the retainers into the sleeve to lock the ball in place) to a second position (that allows the retainers to springback out of the sleeve to release the ball).

Richard A Cloyd↗

NASA NTRS2003

Instrumentation of Java Bytecode for Runtime Analysis

This paper describes JSpy, a system for high-level instrumentation of Java bytecode and its use with JPaX, OUT system for runtime analysis of Java programs. JPaX monitors the execution of temporal logic formulas and performs predicative analysis of deadlocks and data races. JSpy s input is an instrumentation specification, which consists of a collection of rules, where a rule is a predicate/action pair The predicate is a conjunction of syntactic constraints on a Java statement, and the action is a description of logging information to be inserted in the bytecode corresponding to the statement. JSpy is built using JTrek an instrumentation package at a lower level of abstraction.

Goldberg, Allen↗

NASA NTRS2004

Applying Jlint to Space Exploration Software

Java is a very successful programming language which is also becoming widespread in embedded systems, where software correctness is critical. Jlint is a simple but highly efficient static analyzer that checks a Java program for several common errors, such as null pointer exceptions, and overflow errors. It also includes checks for multi-threading problems, such as deadlocks and data races. The case study described here shows the effectiveness of Jlint in find-false positives in the multi-threading warnings gives an insight into design patterns commonly used in multi-threaded code. The results show that a few analysis techniques are sufficient to avoid almost all false positives. These techniques include investigating all possible callers and a few code idioms. Verifying the correct application of these patterns is still crucial, because their correct usage is not trivial.

Artho, Cyrille↗

NASA NTRS2004

Current Status of Hybrid Bearing Damage Detection

Advances in material development and processing have led to the introduction of ceramic hybrid bearings for many applications. The introduction of silicon nitride hybrid bearings into the high pressure oxidizer turbopump, on the space shuttle main engine, led NASA to solve a highly persistent and troublesome bearing problem. Hybrid bearings consist of ceramic balls and steel races. The majority of hybrid bearings utilize Si3N4 balls. The aerospace industry is currently studying the use of hybrid bearings and naturally the failure modes of these bearings become an issue in light of the limited data available. In today s turbine engines and helicopter transmissions, the health of the bearings is detected by the properties of the debris found in the lubrication line when damage begins to occur. Current oil debris sensor technology relies on the magnetic properties of the debris to detect damage. Since the ceramic rolling elements of hybrid bearings have no metallic properties, a new sensing system must be developed to indicate the system health if ceramic components are to be safely implemented in aerospace applications. The ceramic oil debris sensor must be capable of detecting ceramic and metallic component damage with sufficient reliability and forewarning to prevent a catastrophic failure. The objective of this research is to provide a background summary on what is currently known about hybrid bearing failure modes and to report preliminary results on the detection of silicon nitride debris, in oil, using a commercial particle counter.

Dempsey, Paula J.↗

NASA NTRS2002

The Radiata and the evolutionary origins of the bilaterian body plan

The apparent conservation of cellular and molecular developmental mechanisms observed in a handful of bilaterian metazoans has spawned a "race" to reconstruct the bilaterian ancestor. Knowledge of this ancestor would permit us to reconstruct the evolutionary changes that have occurred along specific bilaterian lineages. However, comparisons among extant bilaterians provide an unnecessarily limited view of the ancestral bilaterian. Since the original bilaterians are believed by many to be derived from a radially symmetrical ancestor, additional evidence might be obtained by examining present-day radially symmetrical animals. We briefly review pertinent features of the body plans of the extant radial eumetazoan phyla, the Cnidaria, and Ctenophora, in the context of revealing potential evolutionary links to the bilaterians.

NASA Discipline Evolutionary Biology↗

NASA NTRS1986

Kinetic studies on the control of the bean rust fungus (Uromyces phaseoli L.) by an inhibitor of polyamine biosynthesis

alpha-Difluoromethylornithine (DFMO), a specific and irreversible inhibitor of the polyamine biosynthetic enzyme ornithine decarboxylase, effectively inhibits mycelial growth of several phytopathogenic fungi on defined media in vitro and provides systemic protection of bean plants against infection by Uromyces phaseoli L. race 0 (MV Rajam, AW Galston 1985 Plant Cell Physiol 26: 683-692; MV Rajam et al. 1985 Proc Natl Acad Sci USA 82: 6874-6878). We now find that application of 0.5 millimolar DFMO to unifoliolate leaves of Pinto beans up to 3 days after inoculation with uredospores of U. phaseoli completely inhibits the growth of the pathogen, while application 4 or 5 days after inoculation results in partial protection against the pathogen. Spores do not germinate on the surface of unifoliolate leaves treated with DFMO 1 day before infection, but addition of spermidine to the DFMO treatments partially reverses the inhibitory effect. The titer of polyamines in bean plants did not decline after DFMO treatment; rather, putrescine and spermidine contents actually rose, probably due to the known but paradoxical stimulation of arginine decarboxylase activity by DFMO.

Non-NASA Center↗

NASA NTRS1993

Space Station Freedom: a unique laboratory for gravitational biology research

The advent of Space Station Freedom (SSF) will provide a permanent laboratory in space with unparalleled opportunities to perform biological research. As with any spacecraft there will also be limitations. It is our intent to describe this space laboratory and present a picture of how scientists will conduct research in this unique environment we call space. SSF is an international venture which will continue to serve as a model for other peaceful international efforts. It is hoped that as the human race moves out from this planet back to the moon and then on to Mars that SSF can serve as a successful example of how things can and should be done.

NASA Program Life Sciences Management↗

NASA NTRS2004

Malaria Modeling using Remote Sensing and GIS Technologies

Malaria has been with the human race since the ancient time. In spite of the advances of biomedical research and the completion of genomic mapping of Plasmodium falciparum, the exact mechanisms of how the various strains of parasites evade the human immune system and how they have adapted and become resistant to multiple drugs remain elusive. Perhaps because of these reasons, effective vaccines against malaria are still not available. Worldwide, approximately one to three millions deaths are attributed to malaria annually. With the increased availability of remotely sensed data, researchers in medical entomology, epidemiology and ecology have started to associate environmental and ecological variables with malaria transmission. In several studies, it has been shown that transmission correlates well with certain environmental and ecological parameters, and that remote sensing can be used to measure these determinants. In a NASA project, we have taken a holistic approach to examine how remote sensing and GIs can contribute to vector and malaria controls. To gain a better understanding of the interactions among the possible promoting factors, we have been developing a habitat model, a transmission model, and a risk prediction model, all using remote sensing data as input. Our objectives are: 1) To identify the potential breeding sites of major vector species and the locations for larvicide and insecticide applications in order to reduce costs, lessen the chance of developing pesticide resistance, and minimize the damage to the environment; 2) To develop a malaria transmission model characterizing the interactions among hosts, vectors, parasites, landcover and environment in order to identify the key factors that sustain or intensify malaria transmission, and 3) To develop a risk model to predict the occurrence of malaria and its transmission intensity using epidemiological data and satellite-derived or ground-measured environmental and meteorological data.

Kiang, Richard↗

NASA NTRS1998

Distribution and observed associations of orthostatic blood pressure changes in elderly general medicine outpatients

Factors associated with orthostatic blood pressure change in elderly outpatients were determined by surveying 398 medical clinical outpatients aged 65 years and older. Blood pressure was measured with random-zero sphygmomanometers after patients were 5 minutes in a supine and 5 minutes in a standing position. Orthostatic blood pressure changes were at normally distributed levels with systolic and diastolic pressures dropping an average of 4 mm Hg (standard deviation [SD]=15 mm Hg) and 2 mm Hg (SD=11 mm Hg), respectively. Orthostatic blood pressure changes were unassociated with age, race, sex, body mass, time since eating, symptoms, or other factors. According to multiple linear regression analysis, supine systolic pressure, chronic obstructive pulmonary disease (COPD), and diabetes mellitus were associated with a decrease in systolic pressure on standing. Hypertension, antiarthritic drugs, and abnormal heartbeat were associated with an increase in systolic pressure on standing. For orthostatic diastolic pressure changes, supine diastolic pressure and COPD were associated with a decrease in diastolic pressure on standing. Congestive heart failure was associated with an increase in standing diastolic pressure. Using logistic regression analysis, only supine systolic pressure was associated with a greater than 20-mm Hg drop in systolic pressure (n=53, prevalence=13%). Supine diastolic pressure and COPD were the only variables associated with a greater than 20-mm Hg drop in diastolic pressure (n=16, prevalence=4%). These factors may help physicians in identifying older persons at risk for having orthostatic hypotension.

Non-NASA Center↗

NASA NTRS2005

Toward a Benchmark for Multi-Threaded Testing Tools

Looking for intermittent bugs is a problem that has been getting prominence in testing. Multi-threaded code is becoming very common, mostly on the server side. As there is no silver bullet solution, research focuses on a variety of partial solutions. We outline a road map for combining the research on the different disciplines of testing multi-threaded programs and on evaluating its quality. The project goals are to create a benchmark that can be used to evaluate different solutions, to create a framework with open API's that enables combining techniques in the multithreading domain, and to create a focus for the research in this area around which a community of people who try to solve similar problems with different techniques, could congregate. The benchmark, apart from containing programs with documented bugs, includes other artifacts, such as traces, that are used for evaluating some of the technologies. We have started creating such a bench mrk and detail the lesson learned in the process. The framework will enable technology developers, for example, race detectors, to concentrate on their components and use other ready made components, (e.g., instrumentor) to create a testing solution.

Eytani, Yaniv↗

NASA NTRS2004

A Survey of Formal Methods for Intelligent Swarms

Swarms of intelligent autonomous spacecraft, involving complex behaviors and interactions, are being proposed for future space exploration missions. Such missions provide greater flexibility and offer the possibility of gathering more science data than traditional single spacecraft missions. The emergent properties of swarms make these missions powerful, but simultaneously far more difficult to design, and to assure that the proper behaviors will emerge. These missions are also considerably more complex than previous types of missions, and NASA, like other organizations, has little experience in developing or in verifying and validating these types of missions. A significant challenge when verifying and validating swarms of intelligent interacting agents is how to determine that the possible exponential interactions and emergent behaviors are producing the desired results. Assuring correct behavior and interactions of swarms will be critical to mission success. The Autonomous Nano Technology Swarm (ANTS) mission is an example of one of the swarm types of missions NASA is considering. The ANTS mission will use a swarm of picospacecraft that will fly from Earth orbit to the Asteroid Belt. Using an insect colony analogy, ANTS will be composed of specialized workers for asteroid exploration. Exploration would consist of cataloguing the mass, density, morphology, and chemical composition of the asteroids, including any anomalous concentrations of specific minerals. To perform this task, ANTS would carry miniaturized instruments, such as imagers, spectrometers, and detectors. Since ANTS and other similar missions are going to consist of autonomous spacecraft that may be out of contact with the earth for extended periods of time, and have low bandwidths due to weight constraints, it will be difficult to observe improper behavior and to correct any errors after launch. Providing V&V (verification and validation) for this type of mission is new to NASA, and represents the cutting edge in system correctness, and requires higher levels of assurance than other (traditional) missions that use a single or small number of spacecraft that are deterministic in nature and have near continuous communication access. One of the highest possible levels of assurance comes from the application of formal methods. Formal methods are mathematics-based tools and techniques for specifying and verifying (software and hardware) systems. They are particularly useful for specifying complex parallel systems, such as exemplified by the ANTS mission, where the entire system is difficult for a single person to fully understand, a problem that is multiplied with multiple developers. Once written, a formal specification can be used to prove properties of a system (e.g., the underlying system will go from one state to another or not into a specific state) and check for particular types of errors (e.g., race or livelock conditions). A formal specification can also be used as input to a model checker for further validation. This report gives the results of a survey of formal methods techniques for verification and validation of space missions that use swarm technology. Multiple formal methods were evaluated to determine their effectiveness in modeling and assuring the behavior of swarms of spacecraft using the ANTS mission as an example system. This report is the first result of the project to determine formal approaches that are promising for formally specifying swarm-based systems. From this survey, the most promising approaches were selected and are discussed relative to their possible application to the ANTS mission. Future work will include the application of an integrated approach, based on the selected approaches identified in this report, to the formal specification of the ANTS mission.

Truszkowski, Walt↗

NASA NTRS1996

Molecular Dynamics Calculations

The development of thermodynamics and statistical mechanics is very important in the history of physics, and it underlines the difficulty in dealing with systems involving many bodies, even if those bodies are identical. Macroscopic systems of atoms typically contain so many particles that it would be virtually impossible to follow the behavior of all of the particles involved. Therefore, the behavior of a complete system can only be described or predicted in statistical ways. Under a grant to the NASA Lewis Research Center, scientists at the Case Western Reserve University have been examining the use of modern computing techniques that may be able to investigate and find the behavior of complete systems that have a large number of particles by tracking each particle individually. This is the study of molecular dynamics. In contrast to Monte Carlo techniques, which incorporate uncertainty from the outset, molecular dynamics calculations are fully deterministic. Although it is still impossible to track, even on high-speed computers, each particle in a system of a trillion trillion particles, it has been found that such systems can be well simulated by calculating the trajectories of a few thousand particles. Modern computers and efficient computing strategies have been used to calculate the behavior of a few physical systems and are now being employed to study important problems such as supersonic flows in the laboratory and in space. In particular, an animated video (available in mpeg format--4.4 MB) was produced by Dr. M.J. Woo, now a National Research Council fellow at Lewis, and the G-VIS laboratory at Lewis. This video shows the behavior of supersonic shocks produced by pistons in enclosed cylinders by following exactly the behavior of thousands of particles. The major assumptions made were that the particles involved were hard spheres and that all collisions with the walls and with other particles were fully elastic. The animated video was voted one of two winning videos in a competition held at the meeting of the American Physical Society's Division of Fluid Dynamics, held in Atlanta, Georgia, in November 1994. Of great interest was the result that in every shock there were a few high-speed precursor particles racing ahead of the shock, carrying information about its impending arrival. Most recently, Dr. Woo has been applying molecular dynamics techniques to the problem of determining the drag produced by the space station truss structure as it flies through the thin residual atmosphere of low-Earth orbit. This problem is made difficult by the complex structure of the truss and by the extreme supersonic nature of the flow. A fully filled section of the truss has already been examined, and drag predictions have been made. Molecular dynamics techniques promise to make realistic drag calculations possible even for very complex partially filled truss segments flying at arbitrary angles.

Source record↗

NASA NTRS2005

Effect of Rolling Bearing Refurbishment and Restoration on Bearing Life and Reliability

For nearly four decades it has been a practice in commercial and military aircraft application that rolling-element bearings removed at maintenance or overhaul be reworked and returned to service. The work presented extends previously reported bearing life analysis to consider the depth (Z(45)) to maximum shear stress (45) on stressed volume removal and the effect of replacing the rolling elements with a new set. A simple algebraic relationship was established to determine the L(10) life of bearing races subject to bearing rework. Depending on the extent of rework and based upon theoretical analysis, representative life factors (LF) for bearings subject to rework ranged from 0.87 to 0.99 the lives of new bearings. Based on bearing endurance data, 92 percent of the bearing sets that would be subject to rework would result in L(10) lives equaling and/or exceeding that predicted for new bearings with the remaining 8 percent having the potential to achieve the analytically predicted life of new bearings when one of the rings is replaced at rework.. The potential savings from bearing rework varies from 53 to 82 percent that of new bearings depending on the cost, size and complexity of the bearing.

Zaretsky, Erwin V.↗

NASA NTRS2005

The Need for Fusion Propulsion

Fusion propulsion is inevitable if the human race remains dedicated to exploration of the solar system. There are fundamental reasons why fusion surpasses more traditional approaches to routine crewed missions to Mars, crewed missions to the outer planets, and deep space high speed robotic missions, assuming that reduced trip times, increased payloads, and higher available power are desired. A recent series of informal discussions were held among members from government, academia, and industry concerning fusion propulsion. We compiled a sufficient set of arguments for utilizing fusion in space. If the U.S. is to lead the effort and produce a working system in a reasonable amount of time, NASA must take the initiative, relying on, but not waiting for, DOE guidance. In this talk those arguments for fusion propulsion are presented, along with fusion enabled mission examples, fusion technology trade space, and a proposed outline for future efforts.

Cassibry, Jason↗

NASA NTRS2003

An Indispensable Ingredient: Flight Research and Aircraft Design

Flight research-the art of flying actual vehicles in the atmosphere in order to collect data about their behavior-has played a historic and decisive role in the design of aircraft. Naturally, wind tunnel experiments, computational fluid dynamics, and mathematical analyses all informed the judgments of the individuals who conceived of new aircraft. But flight research has offered moments of realization found in no other method. Engineer Dale Reed and research pilot Milt Thompson experienced one such epiphany on March 1, 1963, at the National Aeronautics and Space Administration s Dryden Flight Research Center in Edwards, California. On that date, Thompson sat in the cockpit of a small, simple, gumdrop-shaped aircraft known as the M2-F1, lashed by a long towline to a late-model Pontiac Catalina. As the Pontiac raced across Rogers Dry Lake, it eventually gained enough speed to make the M2-F1 airborne. Thompson braced himself for the world s first flight in a vehicle of its kind, called a lifting body because of its high lift-to-drag ratio. Reed later recounted what he saw:

Gorn, Michael H.↗

NASA NTRS2003

Designing for the Edge of Space and Beyond

Despite the fanciful predictions of Eugen Sanger, Wernher von Braun, and a wealth of science fiction novelists, it was not until the mid-1950s that the first piloted spacecraft design was undertaken in earnest. It was the height of the Cold War, and the paranoia that swept the country and the military had resulted in the largest arms race the world had ever seen. In aviation the desire was to go higher, faster, and farther than ever before. In response to a need for basic research into the ever-increasing speeds and altitudes, the National Advisory Committee on Aeronautics (NACA) began preliminary research into a piloted vehicle that could exceed five times the speed of sound. The research was felt necessary to support both unmanned missile programs and the eventual development of hypersonic combat aircraft. Interestingly, the group of researchers that took the lead in developing the concept (led by John V. Becker) at the NACA s Langley Laboratory added a new wrinkle-they wanted to be able to leave the sensible atmosphere for a few minutes in order to gain a preliminary understanding of space flight2 At the time it was generally felt that piloted space flight would not take place until the turn of the century, although contemporary science fiction-a genre that enjoyed a resurgence of popularity in the mid-1 950s-usually showed it coming much earlier. In fact, many serious researchers believed that the group at Langley should remove the "space leap" from their concept for a hypersonic research air~lane.~ However, the basic designs for a very high speed airplane and for one capable of short excursions outside the atmosphere were not radically different, so the capability remained.

Jenkins, Dennis R.↗