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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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Report describes research to evaluate perfluoroethane, perfluoropropane, and perfluoro-n-butane as replacements for Halon 1301 as working fluids in fire extinguishers. Because Halon 1301 has potential to deplete Earth's ozone layer, its production scheduled to end by year 2000.
Human body models are geometric structures which may be ultimately controlled by kinematically manipulating their joints, but for animation, it is desirable to control them in terms of task-level goals. We address a fundamental problem in achieving task-level postural goals: controlling massively redundant degrees of freedom. We reduce the degrees of freedom by introducing significant control points and vectors, e.g., pelvis forward vector, palm up vector, and torso up vector, etc. This reduced set of parameters are used to enumerate primitive motions and motion dependencies among them, and thus to select from a small set of alternative postures (e.g., bend vs. squat to lower shoulder height). A plan for a given goal is found by incrementally constructing a goal/constraint set based on the given goal, motion dependencies, collision avoidance requirements, and discovered failures. Global postures satisfying a given goal/constraint set are determined with the help of incremental mental simulation which uses a robust inverse kinematics algorithm. The contributions of the present work are: (1) There is no need to specify beforehand the final goal configuration, which is unrealistic for the human body, and (2) the degrees of freedom problem becomes easier by representing body configurations in terms of 'lumped' control parameters, that is, control points and vectors.
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Charts are presented that permit the estimation of F-3 and F-4 knock-limited performance ratings for certain ternary and quaternary fuel blends. Ratings for various ternary and quaternary blends estimated from these charts compare favorably with experimental F-3 and F-4 ratings. Because of the unusual behavior of some of the aromatic blends in the F-3 engine, the charts for aromatic-paraffinic blends are probably less accurate than the charts for purely paraffinic blends.
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DMES, a volatile liquid, is used by NASA to waterproof the Orbiter thermal protective system. During waterproofing operations at the Oribter Processing Facility at KSC, workers could be exposed to DMES vapor. To assess the toxicity of DMES, acute and subchronic (2-week and 13-week) inhalation studies were conducted with rats. Studies were also conducted to assess the potential of DMES. Inhalation exposure concentrations ranged from 40 ppm to 4000 ppm. No mortality was observed during the studies. Exposures to 2100 ppm produced narcosis and ataxia. Post-exposure recovery from these CNS effects was rapid (less than 1 hr). These effects were concentration-dependent and relatively independent of exposure length. Exposure to 3000 ppm for 2 weeks (5 h/d, 5 d/wk) produced testicular toxicity. The 13-week study yielded similar results. Results from the genotoxicity assays (in vivo/in vitro unscheduled DNA synthesis in rat primary heptaocytes, chromosomal aberrations in rat bone marrow cells; reverse gene mutation in Salmonella typhimurium; and forward mutation in Chinese hamster culture cells) were negative. These studies indicated that DMES is mildly to moderately toxic but not a multagen.
The major challenge facing the world's aircraft/airspace system (AAS) today is the need to provide increased capacity, while reducing delays, increasing the efficiency of flight operations, and improving safety. Technologies are emerging that should improve the performance of the system, but which could also introduce uncertainty, disputes, and inefficiency if not properly implemented. The aim of our research is to apply techniques from intelligent control theory and decision-making theory to define an Intelligent Aircraft/Airspace System (IAAS) for the year 2025. The IAAS would make effective use of the technical capabilities of all parts of the system to meet the demand for increased capacity with improved performance.
The Community Open Source Program Office (COSPO) has developed an architecture for the intelligence community's new Open Source Information System (OSIS). The architecture is a multi-phased program featuring connectivity, interoperability, and functionality. OSIS is based on a distributed architecture concept. The system is designed to function as a virtual entity. OSIS will be a restricted (non-public), user configured network employing Internet communications. Privacy and authentication will be provided through firewall protection. Connection to OSIS can be made through any server on the Internet or through dial-up modems provided the appropriate firewall authentication system is installed on the client.
There is currently a growing interest in the aeronautical community to assess the effects of the increasing levels of automation on pilots' performance and overall safety. The first effect of automation is the change in the nature of the pilot's role on the flight deck. Pilots have become supervisors who monitor aircraft systems in usual situations and intervene only when unanticipated events occur. Instead of 'hand flying' the airplane, pilots contribute to the control of aircraft by acting as mediators, instructions given to the automation. By eliminating the need for manually controlling normal situations, such a role division has reduced the opportunities for the pilot to acquire experience and skills necessary to safely cope with abnormal events. Difficulties in assessing the state and behavior of automation arise mainly from four factors: (1) the complexity of current systems and consequence mode-related problems; (2) the intrinsic autonomy of automation which is able to fire mode transitions without explicit commands from the pilots; (3) the bad quality of feed-back from the control systems displays and interfaces to the pilots; and (4) the fact that the automation currently has no explicit representation of the current pilots' intentions and strategy. Assuming certification has among its major goals to guarantee the passengers' and pilots' safety and the airplane integrity under normal and abnormal operational conditions, the authors suggest it would be particularly fruitful to come up with a conceptual reference system providing the certification authorities both with a theoretical framework and a list of principles usable for assessing the quality of the equipment and designs under examination. This is precisely the scope of this paper. However, the authors recognize that the conceptual presented is still under development and would thus be best considered as a source of reflection for the design, evaluation and certification processes of advanced aviation technologies.
Nearly every professional would like to have a personal assistant to perform the physical and mental work of searching libraries for needed information. This paper describes a tool which performs this function using commonly available Internet services. The promises and difficulties of developing such a tool are described.
A pad for cleaning up liquid spills is described which contains a porous surface covering, and an absorbent interior containing chemically reactive reagents for neutralizing noxious chemicals within the spilled liquid. The porous surface and the absorbent component would normally consist of chemically resistant materials allowing tentative spill to pass. The absorbent interior which contains the neutralizing reagents can but is not required to be chemically resilient and conducts the liquid chemically reactive reagents where the dangerous and undesirable chemicals within the chemical spill are then neutralized as well as removed from the premises.
A pad for cleaning up liquid spills is described which contains a porous surface covering, and an absorbent interior containing chemically reactive reagents for neutralizing noxious chemicals within the spilled liquid. The porous surface and the absorbent component would normally consist of chemically resistant materials allowing tentative spill to pass. The absorbent interior which contains the neutralizing reagents can but is not required to be chemically resilient and conducts the liquid chemical spill towards the absorbent interior containing the chemically reactive reagents where the dangerous and undesirable chemicals within the chemical spill are then neutralized as well as removed from the premises.
Buckets are an aggregative, intelligent construct for publishing in digital libraries. The goal of research projects is to produce information. This information is often instantiated in several forms, differentiated by semantic types (report, software, video, datasets, etc.). A given semantic type can be further differentiated by syntactic representations as well (PostScript version, PDF version, Word version, etc.). Although the information was created together and subtle relationships can exist between them, different semantic instantiations are generally segregated along currently obsolete media boundaries. Reports are placed in report archives, software might go into a software archive, but most of the data and supporting materials are likely to be kept in informal personal archives or discarded altogether. Buckets provide an archive-independent container construct in which all related semantic and syntactic data types and objects can be logically grouped together, archived, and manipulated as a single object. Furthermore, buckets are active archival objects and can communicate with each other, people, or arbitrary network services.
The amounts of four different Freons adsorbed by carbon, silica gel, alumina, and molecular sieves were determined at pressures up to 225 lb/sq in. The carbon adsorbed 50 to 100 percent and the silica gels, 30 to 50 percent of their own weight of Freon. Several adsorbed systems were tested in a standard dry-powder extinguisher on a 5-sq-ft gasoline fire for their effectiveness in putting out a fire. One of the Freons (bromotrifluoromethane) and carbon extinguished fires about as well as bicarbonate powder and nitrogen.
A crash-fire protection system to suppress the ignition of crash-spilled fuel that may be ingested by a T-56 turbopropeller engine is described. This system includes means for rapidly extinguishing the combustor flame and means for cooling and inerting with water the hot engine parts likely to ignite engine-ingested fuel. Combustion-chamber flames were extinguished in 0.07 second at the engine fuel manifold. Hot engine parts were inerted and cooled by 52 pounds of water discharged at ten engine stations. Performance trials of the crash-fire prevention system were conducted by bringing the engine up to takeoff temperature, stopping the normal fuel flow to the engine, starting the water discharge, and then spraying fuel into the engine to simulate crash-ingested fuel. No fires occurred during these trials, although fuel was sprayed into the engine from 0.3 second to 15 minutes after actuating the crash-fire protection system.
This paper describes two separate efforts that used the SPIN model checker to verify deep space autonomy flight software. The first effort occurred at the beginning of a spiral development process and found five concurrency errors early in the design cycle that the developers acknowledge would not have been found through testing. This effort required a substantial manual modeling effort involving both abstraction and translation from the prototype LISP code to the PROMELA language used by SPIN. This experience and others led to research to address the gap between formal method tools and the development cycle used by software developers. The Java PathFinder tool which directly translates from Java to PROMELA was developed as part of this research, as well as automatic abstraction tools. In 1999 the flight software flew on a space mission, and a deadlock occurred in a sibling subsystem to the one which was the focus of the first verification effort. A second quick-response "cleanroom" verification effort found the concurrency error in a short amount of time. The error was isomorphic to one of the concurrency errors found during the first verification effort. The paper demonstrates that formal methods tools can find concurrency errors that indeed lead to loss of spacecraft functions, even for the complex software required for autonomy. Second, it describes progress in automatic translation and abstraction that eventually will enable formal methods tools to be inserted directly into the aerospace software development cycle.
This research is focused on the design, development and implementation of an industry, military and commercial standard testing cell for surface coatings, which focuses on advanced non-chromate materials technology and their commercialization. Currently, within both private and commercial sectors, chromates are used in the corrosion prevention. processes. However, there is a great demand for chromate-free systems that are able to provide equal protection. At the end of this effort, it is intended that a patented alternative to chromate conversion coatings would be tested and processed for commercialization. Thus far, research studies have been concerned primarily with current corrosion knowledge and testing methods. Corrosion can be classified into five categories: The first type is uniform corrosion which is dominated by a uniform thinning due to an even and regular loss of metal. The second type is called localized corrosion in which most of the loss occurs in discrete areas. The third type, metallurgically influenced corrosion is a form of attack where metallurgy plays a significant role. The fourth type, titled mechanically assisted degradation is a form of attack where velocity, abrasion, and hydrodynamics control the corrosion process. The last type of corrosion is defined as environmentally induced cracking which occurs when cracks are produced under specific, premeditated stress. Oddly enough, with these varying classifications, there are not as many standardized corrosion testing sites. Two of the most common testing methods for corrosion are salt spray testing and filiform. Although neither has proven to be absolute, in terms of the resulting observations, our research aims to help provide data that may be used to support the standardization for corrosion testing. We would acquire and use a Singleton Cyclic Corrosion Testing Chamber. Singleton test chambers perform a wide range of commonly used catalytic corrosion tests. They are used throughout the industry, some of which are - automotive, aerospace, electronic and many more. In addition to this, Singleton test chambers are fully expandable to accommodate cyclic corrosion testing needs. Singleton chambers are also designed for complete compliance and conformity with ASTM (American Society for Testing and Materials), military and commercial standards.
Polyimide-silica hybrids composed of an organic precursor containing a novel phenylethynyl imide silane and an inorganic precursor were evaluated as an adhesion-promoting interphase between surface-treated titanium alloy and a phenylethynyl-containing imide adhesive. The phenylethynyl groups present in the organic precursor, either as a pendent or end group, can bond chemically with a phenylethynyl-containing imide adhesive during processing, while the silane groups of the organic precursor would react chemically with the inorganic precursor. In addition, the inorganic precursor is able to react with the titanium alloy to form a stable bond with the metal oxide. Bond strength and durability were evaluated by single lap shear tests at various conditions. Lap shear specimens exhibited predominantly cohesive failure after a 3-d water boil with 92% retention of the initial room temperature strength. Morphology and chemical composition of the hybrid interphase were investigated with scanning electron microscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, which revealed development of a silicon-gradient, hybrid structure between the metal substrate and the adhesive.