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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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User-Macro-Interface computer program provides interactive interface enabling human operator to plan tasks for multiple-arm telerobot, cause robot to execute tasks, and monitor robot. Enables operator to specify that robot execute various tasks and subtasks under various mixtures of manual or automatic control. Well suited for use where environment of task poorly modeled or unplanned or task unexpected.
The combination of thermal and mechanical loading expected in practice means that constitutive equations of metal matrix composites must be developed which deal with time-independent and time-dependent irreversible deformation. Also, the internal state of composites is extremely complicated which underlines the need to formulate macroscopic constitutive equations with a limited number of state variables which represent the internal state at the micro level. One available method for calculating the macro properties of composites in terms of the distribution and properties of the constituent materials is the method of homogenization whose formulation is based on the periodicity of the substructure of the composite. A homogenization procedure was developed which lends itself to the use of the finite element procedure. The efficiency of these procedures, to determine the macroscopic properties of a composite system from its constituent properties, was demonstrated utilizing an aluminum plate perforated by directionally oriented slits. The selection of this problem is based on the fact that, extensive experimental results exist, the macroscopic response is highly anisotropic, and that the slits provide very high stress gradients which severely test the effectiveness of the computational procedures. Furthermore, both elastic and plastic properties were investigated so that the application to practical systems with inelastic deformation should be able to proceed without difficulty. The effectiveness of the procedures was rigorously checked against experimental results and with the predictions of approximate calculations. Using the computational results it is illustrated how macroscopic constitutive equations can be expressed in forms of the elastic and limit load behavior.
Here, it is explained why the FORCE parallel programming language is easily portable among six different shared-memory microprocessors, and how a two-level macro preprocessor makes it possible to hide low level machine dependencies and to build machine-independent high level constructs on top of them. These FORCE constructs make it possible to write portable parallel programs largely independent of the number of processes and the specific shared memory multiprocessor executing them.
The overall objective is to develop efficient and economical separation and recovery methods for the platinum group and other precious metals. The separation of Pd(II) from Pt(II), Ir(III), and Rh(III) with trioctylphosphine oxide (TOPO) in heptane using centrifugal partition chromatography (CPC) was investigated. Activities to achieve this objective focussed on selection and evaluation of extraction systems for the PGM and modification of selected systems for multistage operation with a view to scaling up to desired macro levels. On the basis of preliminary evaluation of a series of simple metal complexing agents and chelating agents, the TOPO in heptane was selected as a likely system for isolating of Pd(II) and Pt(II) from the other PGM. A multistage apparatus capable of configuration as a simple rugged device, a centrifugal partition chromatograph (CPC), was shown to be effective. The extraction of Pd(II) was studied by CPC and batch solvent extraction. The distribution ratios for Pd(II) determined by both methods agree well. In low HCl concentrations (less than 0.1 M), the extracted species was PdCl2.(TOPO)2, irrespective of the chloride concentration, while at acid concentrations above 0.1 M, the Pd was extracted as the ion pair, 2(TOPO.H+).(PdCl4)2-. Base line separation of Pd(II) and Pt(II) in CPC was obtained under a variety of chloride and HCl concentration. It was demonstrated that the efficiency of CPC for metal separation was limited by chemical kinetic factors rather than instrumental factors, strongly suggesting that dramatic improvements can be achieved by studying reaction kinetics of formation and dissociation of the extractable metal complex.
Two specimen configuration of a (0/90)2s SCS-6/Ti-15-3 laminate were tested and analyzed: a center hole (CH) specimen and a double edge notch (DEN) specimen. The two specimen configurations failed at similar stress levels. Two analytical techniques, a 3-D finite-element analysis and a macro-micromechanical analysis were used to predict the overall stress-deformation behavior and the notch-tip fiber-matrix interface stresses in both configurations.
An interactive user interface, User-Macro-Interface (UMI), and its complete task execution system are developed and implemented for utilization by an operator to describe, simulate and execute tasks on a multiarm telerobot. The sequences or primitives can be executed on a graphics simulator or on the JPL Telerobot which incorporates two task execution manipulators, one manipulation used for positioning cameras, and two 6-degree-of-freedom force-reflecting hand controllers employed for shared and teleoperation modes of execution. The UMI interface is to be used as the operator interface at a local command site to prepare and send commands to a remote space telerobot.
The objective of the Advanced Telerobotics System Technology Task is to develop/prototype advanced telerobotics supervisory and shared control to enhance Intra-Vehicular Activity (IVA) teleoperation in the Space Station. The technology provides enhanced telerobotics capabilities while operating within the expected constraints of computation limitations, time delay, and bus bandwidth. A local site operator interface has also been developed for specifying teleoperation and shared control modes as well as supervised autonomous macros for execution at the remote site. The primary objective of the task is to transfer the advanced technology to appropriate flight centers to enhance the baseline Station capabilities.
Various papers on particle astrophysics are presented. Individual topics addressed include: the NASA cosmic ray (CR) program for the 1990s and beyond, SAMPEX Mission overview, the Advanced Composition Explorer, Positron Electron Magnet Spectrometer for the Eos Mission, Heavy Nucleus Collector for Space Station, the Astromag Facility, Large Isotope Spectrometer for Astromag, the Solar Probe Mission, the Mercury Dual Orbiter Mission, CRs in the heliosphere, origin of high-energy Galactic CRs, CR studies with the Gamma-Ray Observatory, gamma-ray astronomy at 1 TeV, experimental search for point sources above 1 TeV, the UMC Extensive Air Shower Array, status of the MACRO experiment. Also discussed are: CRs above 1 TeV/n and neutrino astronomy, abundance of ultraheavy nuclei in solar energetic particles, CR studies with an interstellar probe, isotopic composition of CR nuclei beyond the iron peak, experimental studies of CR isotopic composition up to Zr-40, use of accelerators in particle astrophysics, development of long-duration ballooning in Antarctica, Lunar-Based Heavy Nucleus Detector, neutrino astronomy on the moon, gamma rays at airplane altitudes, source composition of CRs.
The statistics of convective soil patterns are analyzed using statistical crystallography. An underlying hierarchy of order is found to span four orders of magnitude in characteristic pattern length. Strict mathematical requirements determine the two-dimensional (2D) topology, such that random partitioning of space yields a predictable statistical geometry for polygons. For all lengths, Aboav's and Lewis's laws are verified; this result is consistent both with the need to fill 2D space and most significantly with energy carried not by the patterns' interior, but by the boundaries. Together, this suggests a common mechanism of formation for both micro- and macro-freezing patterns.
This paper presents the preliminary results of an on-going study of the near-tip mechanics of mode-I cracking in brittle matrix composite laminates. A finite element model is developed within the context of two competing characteristic lengths present in the composite: the microstructural length (the thickness of the layers) and a macro-length (crack-length, uncracked ligament size, etc.). For various values of the parameters which describe the ratio of these lengths and the constituent properties, the stresses ahead of a crack perpendicular to the laminates are compared with those predicted by assuming the composite is homogeneous orthotropic. The results can be used to determine the conditions for which homogenization can provide a sufficiently accurate description of the stresses in the vicinity of the crack-tip.
The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113-432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg x 0.1 deg for illuminated disk observations and 1 deg x 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg x 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170-432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.
Computer programs developed for use in controlling automated welding system described in MFS-28578. Together with control computer, computer input and output devices and control sensors and actuators, provide flexible capability for planning and implementation of schemes for automated welding of specific workpieces. Developed according to macro- and task-level programming schemes, which increases productivity and consistency by reducing amount of "teaching" of system by technician. System provides for three-dimensional mathematical modeling of workpieces, work cells, robots, and positioners.
An application for parallel computation on a combined cluster of powerful workstations and supercomputers was developed. A Parallel Virtual Machine (PVM) is used as message passage language on a macro-tasking parallelization of the Aerodynamic Inverse Design and Analysis for a Full Engine computer code. The heterogeneous nature of the cluster is perfectly handled by the controlling host machine. Communication is established via Ethernet with the TCP/IP protocol over an open network. A reasonable overhead is imposed for internode communication, rendering an efficient utilization of the engaged processors. Perhaps one of the most interesting features of the system is its versatile nature, that permits the usage of the computational resources available that are experiencing less use at a given point in time.
In this paper, a micro-opportunistic approach to factory scheduling was described that closely monitors the evolution of bottlenecks during the construction of the schedule and continuously redirects search towards the bottleneck that appears to be most critical. This approach differs from earlier opportunistic approaches, as it does not require scheduling large resource subproblems or large job subproblems before revising the current scheduling strategy. This micro-opportunistic approach was implemented in the context of the MICRO-BOSS factory scheduling system. A study comparing MICRO-BOSS against a macro-opportunistic scheduler suggests that the additional flexibility of the micro-opportunistic approach to scheduling generally yields important reductions in both tardiness and inventory. Current research efforts include: adaptation of MICRO-BOSS to deal with sequence-dependent setups and development of micro-opportunistic reactive scheduling techniques that will enable the system to patch the schedule in the presence of contingencies such as machine breakdowns, raw materials arriving late, job cancellations, etc.
The Center for Cell Research (CCR) is a NASA Center for the Commercial Development of Space which has as its main goal encouraging industry-driven biomedical/biotechnology space projects. Space Station Freedom (SSF) will provide long duration, crew-tended microgravity environments which will enhance the opportunities for commercial biomedical/biotechnology projects in bioseparations and physiological testing. The CCR bioseparations program, known as USCEPS (for United States Commercial Electrophoresis Program in Space), is developing access for American industry to continuous-flow electrophoresis aboard SSF. In space, considerable scale-up of continuous free-flow electrophoresis is possible for cells, sub cellular particles, proteins, growth factors, and other biological products. The lack of sedemination and buoyancy-driven convection flow enhances purity of separations and the amount of material processed/time. Through the CCR's physiological testing program, commercial organizations will have access aboard SSF to physiological systems experiments (PSE's); the Penn State Biomodule; and telemicroscopy. Physiological systems experiments involve the use of live animals for pharmaceutical product testing and discovery research. The Penn State Biomodule is a computer-controlled mini lab useful for projects involving live cells or tissues and macro molecular assembly studies, including protein crystallization. Telemicroscopy will enable staff on Earth to manipulate and monitor microscopic specimens on SSF for product development and discovery research or for medical diagnosis of astronaut health problems. Space-based product processing, testing, development, and discovery research using USCEPS and CCR's physiological testing program offer new routes to improved health on Earth. Direct crew involvement-in biomedical/biotechnology projects aboard SSF will enable better experimental outcomes. The current data base shows that there is reason for considerable optimism regarding what the CCDS program and the biomedical/biotechnology industry can expect to gain from a permanent manned presence in space.
This report outlines methods of analysis for the buckling of thin-walled circumferentially and longitudinally stiffened cylindrical shells. Methods of analysis for the various failure modes are presented in one cohesive package. Where applicable, more than one method of analysis for a failure mode is presented along with standard practices. The results of this report are primarily intended for use in launch vehicle design in the elastic range. A Microsoft Excel worksheet with accompanying macros has been developed to automate the analysis procedures.
A methodology is developed to computationally assess the probabilistic composite material properties at all composite scale levels due to the uncertainties in the constituent (fiber and matrix) properties and in the fabrication process variables. The methodology is computationally efficient for simulating the probability distributions of material properties. The sensitivity of the probabilistic composite material property to each random variable is determined. This information can be used to reduce undesirable uncertainties in material properties at the macro scale of the composite by reducing the uncertainties in the most influential random variables at the micro scale. This methodology was implemented into the computer code PICAN (Probabilistic Integrated Composite ANalyzer). The accuracy and efficiency of this methodology are demonstrated by simulating the uncertainties in the material properties of a typical laminate and comparing the results with the Monte Carlo simulation method. The experimental data of composite material properties at all scales fall within the scatters predicted by PICAN.
In this paper, a micro-opportunistic approach to factory scheduling was described that closely monitors the evolution of bottlenecks during the construction of the schedule, and continuously redirects search towards the bottleneck that appears to be most critical. This approach differs from earlier opportunistic approaches, as it does not require scheduling large resource subproblems or large job subproblems before revising the current scheduling strategy. This micro-opportunistic approach was implemented in the context of the MICRO-BOSS factory scheduling system. A study comparing MICRO-BOSS against a macro-opportunistic scheduler suggests that the additional flexibility of the micro-opportunistic approach to scheduling generally yields important reductions in both tardiness and inventory.