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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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The Kokkos library implements thread-parallel execution policies and shared-memory multidimensional array data structures that enable applications and domain libraries to develop computational kernels that are performance portable across multicore-CPU and manycore-accelerator (e.g. GPU) computing architectures.
Software library for parallel rapid order N and graph-based recursive electronic structure solvers with applications to material science, chemistry, and molecular biology.
Almost all science and engineering applications eventually stop scaling: their runtime no longer decreases as available computational resources increase. Therefore, many applications will struggle to efficiently use emerging extreme-scale high-performance, parallel, and distributed systems. libEnsemble is a complete Python toolkit and workflow system for intelligently driving ensembles of experiments or simulations at massive scales. It enables and encourages multidisciplinary design, decision, and inference studies portably running on laptops, clusters, and supercomputers.
The Airborne Science Office (ASO) of the Ames Research Center has for 10 years operated an airborne scientific research program in infrared astronomy and other disciplines. The Lear Jet, CV-990, and C-141 flying laboratories are flown by ASO crews, while the major responsibility for defining, developing, and operating the experimental equipment is placed on individual researchers, who have included scientists from many countries. The ASSESS (Airborne Science/Shuttle Experiment Systems Simulation) program consists of two phases: Phase A documents the present management and operational practices of the ASO, and Phase B consists of airborne research missions constrained (for example, by crew confinement) to simulate certain aspects of experimental operations on Shuttle/Spacelab missions. Various parallels between the Airborne Science Program and Spacelab are pointed out and their applications to Spacelab planning are discussed.
Porous-floating-gate, "vertical" field-effect transistor proposed as programmable analog memory device especially suitable for use in electronic neural networks. Analog value of electrical conductance of device represents synaptic weight (strength of synaptic connection) repeatedly modified by application of suitable writing or erasing voltage. Suited for hardware implementations of massively parallel neural-network architectures for two important reasons: vertical transistor structure requires only two external electrodes, and use of tailored amorphous semiconductors provides choice of very wide range of low conductivity values, dictated by overall power dissipation requirements in massively parallel neural-network circuits.
Research on the computational fluid dynamics (CFD) code evaluation with emphasis on supercomputing in reacting flows is discussed. Advantages of unstructured grids, multigrids, adaptive methods, improved flow solvers, vector processing, parallel processing, and reduction of memory requirements are discussed. As examples, researchers include applications of supercomputing to reacting flow Navier-Stokes equations including shock waves and turbulence and combustion instability problems associated with solid and liquid propellants. Evaluation of codes developed by other organizations are not included. Instead, the basic criteria for accuracy and efficiency have been established, and some applications on rocket combustion have been made. Research toward an ultimate goal, the most accurate and efficient CFD code, is in progress and will continue for years to come.
Advances in computer architecture, computer science, computational methods, and constituent technologies are expected to lead to significant advances in the performance of scientific supercomputing system capabilities over the next decade. By the year 2000, single 1-in-sq dies are projected to incorporate four processors, each of which would be operating faster than 750 million instructions per second (MIPS) for a total on-chip processing performance in excess of 2000 MIPS. Scalable parallel processors can be expected to contain thousands of such multiple processor chips. In general, semiconductor performance advances appear to change about one order of magnitude every five years. Rotating magnetic memory and communications technology are not advancing as rapidly, with the result that the allocation of functions within the system configurations fo future supercomputer systems will require important changes. Availability of massively parallel heterogeneous processing capabilities should be a catalyst leading to new approaches for applications.
File Servers and Supercomputing environments need high performance networks to balance the I/O requirements seen in today's demanding computing scenarios. UltraNet is one solution which permits both high aggregate transfer rates and high task-to-task transfer rates as demonstrated in actual tests. UltraNet provides this capability as both a Server-to-Server and Server-to-Client access network giving the supercomputing center the following advantages highest performance Transport Level connections (to 40 MBytes/sec effective rates); matches the throughput of the emerging high performance disk technologies, such as RAID, parallel head transfer devices and software striping; supports standard network and file system applications using SOCKET's based application program interface such as FTP, rcp, rdump, etc.; supports access to the Network File System (NFS) and LARGE aggregate bandwidth for large NFS usage; provides access to a distributed, hierarchical data server capability using DISCOS UniTree product; supports file server solutions available from multiple vendors, including Cray, Convex, Alliant, FPS, IBM, and others.
A large class of scientific and engineering applications may be classified as irregular and loosely synchronous from the perspective of parallel processing. We present a partial classification of such problems. This classification has motivated us to enhance FORTRAN D to provide language support for irregular, loosely synchronous problems. We present techniques for parallelization of such problems in the context of FORTRAN D.
This report presents the results of Phase 1 research to develop a methodology for performing large-scale Multi-disciplinary Stochastic Optimization (MSO) for the design of aerospace systems ranging from aeropropulsion components to complete aircraft configurations. The current research recognizes that such design optimization problems are computationally expensive, and require the use of either massively parallel or multiple-processor computers. The methodology also recognizes that many operational and performance parameters are uncertain, and that uncertainty must be considered explicitly to achieve optimum performance and cost. The objective of this Phase 1 research was to initialize the development of an MSO methodology that is portable to a wide variety of hardware platforms, while achieving efficient, large-scale parallelism when multiple processors are available. The first effort in the project was a literature review of available computer hardware, as well as review of portable, parallel programming environments. The first effort was to implement the MSO methodology for a problem using the portable parallel programming language, Parallel Virtual Machine (PVM). The third and final effort was to demonstrate the example on a variety of computers, including a distributed-memory multiprocessor, a distributed-memory network of workstations, and a single-processor workstation. Results indicate the MSO methodology can be well-applied towards large-scale aerospace design problems. Nearly perfect linear speedup was demonstrated for computation of optimization sensitivity coefficients on both a 128-node distributed-memory multiprocessor (the Intel iPSC/860) and a network of workstations (speedups of almost 19 times achieved for 20 workstations). Very high parallel efficiencies (75 percent for 31 processors and 60 percent for 50 processors) were also achieved for computation of aerodynamic influence coefficients on the Intel. Finally, the multi-level parallelization strategy that will be needed for large-scale MSO problems was demonstrated to be highly efficient. The same parallel code instructions were used on both platforms, demonstrating portability. There are many applications for which MSO can be applied, including NASA's High-Speed-Civil Transport, and advanced propulsion systems. The use of MSO will reduce design and development time and testing costs dramatically.
This paper reviews Lilley s reformulation of Lighthill s equation and shows that it can be obtained as a special case of a much more general acoustic analogy. It also shows how this generalized analogy can be used to eliminate some of the difficulties that arise when more conventional parallel flow analogies are applied to high speed jets. And, finally, some recent applications of these ideas are discussed.
Today, space is no longer just a field of advanced technological development and of scientific research of excellence, but has become an essential asset for everyday life. Space has spurred countless scientific and technological achievements which are commonly used in aeronautics, medicine, material science and production, in information and communications technology. In parallel, more and more services are carried out through the use of space applications, ranging from detection of natural disasters and environmental monitoring to global navigation and telecommunication. Using space missions to build a better understanding of the universe fulfills our centuries-old curiosity and leads humanity into the future, opening up new frontiers of knowledge. The International Astronautical Congresses have always represented an arena in which issues have been discussed with friendship and among experts: scientists, technicians and managers from universities, agencies, research centres and industry. At the same time it introduces students and young professionals to the field.
Software library for parallel rapid order N and graph-based recursive electronic structure solvers with applications to material science, chemistry, and molecular biology.
Systems, apparatuses, and methods for implementing bufferless communication for redundant multithreading applications using register permutation are disclosed. In one embodiment, a system includes a parallel processing unit, a register file, and a scheduler. The scheduler is configured to cause execution of a plurality of threads to be performed in lockstep on the parallel processing unit. The plurality of threads include a first thread and a second thread executing on adjacent first and second lanes, respectively, of the parallel processing unit. The second thread is configured to perform a register permute operation from a first register location to a second register location in a first instruction cycle, with the second register location associated with the second processing lane. The second thread is configured to read from the second register location in a second instruction cycle, wherein the first and second instruction cycles are successive instruction cycles.
This paper reports on a surface impedance measurement of a niobium titanium superconducting radio frequency (SRF) cavity in a magnetic field (up to $10\,{\rm T}$). A novel method is employed to decompose the surface resistance contributions of the cylindrical cavity end caps and walls using measurements from multiple $TM$ cavity modes. The results confirm that quality factor degradation of a NbTi SRF cavity in a high magnetic field is primarily from surfaces perpendicular to the field (the cavity end caps), while parallel surface resistances (the walls) remain relatively constant. This result is encouraging for applications needing high Q cavities in strong magnetic fields, such as the Axion Dark Matter eXperiment (ADMX), because it opens the possibility of hybrid SRF cavity construction to replace conventional copper cavities.
Silicon carbide (SiC) is a leading candidate for accident tolerant fuel. Testing of SiC in autoclaves at 360 C. degrees in simulated coolant resulted in little corrosion. However, testing of SiC tubes in the Massachusetts Institute of Technology (MIT) reactor manufactured in the same way had unacceptable corrosion levels. This in-reactor SiC corrosion issue is now being addressed by Westinghouse in tests being carried out at our Churchill, PA facility and in tests in the MIT reactor. The suspected driver for the excessive corrosion is the generation of oxidative water radiolysis products in the core. The MIT reactor was identified as running at H{sub 2} levels of ∼20 to 22 cc/kg coolant (cubic centimeters standard temperature and pressure per kilogram coolant) which were below those normally specified in operating pressurized water reactors (PWRs) of 25 to 50 cc/kg. Hydrogen is used to react with the radiolysis products to reduce them to water. The current MIT reactor tests will be run at H{sub 2} concentration levels of ∼50 cc/kg. The applicability of this approach has been supported by recent papers in the literature. Parallel testing at Churchill is being carried out to verify the efficacy of this approach using autoclaves operating at 345 C.degrees with H{sub 2}O{sub 2} injection to simulate the water radiolysis products. Various concentrations of H{sub 2} are being tested to determine the effect on SiC corrosion rate. Further studies are underway to investigate the effects of different SiC fabrication and structural parameters and to optimize for improved corrosion performance. This paper compares the results of the corrosion tests in the MIT reactor and the autoclave tests with H{sub 2}O{sub 2} injection and the effect of H{sub 2} injection on the SiC corrosion rate. The results of the autoclave tests with H{sub 2}O{sub 2} addition indicate that corrosion rates for SiC can be achieved that are much higher than those achieved in a reactor. It appears that the use of H{sub 2}O{sub 2} addition in flow through loops to simulate the corrosion rate of SiC samples in reactor is feasible. The use of H{sub 2} addition to reduce the corrosion rate in-reactor of SiC appears to be feasible.
Growing demands for computing power in applications such as energy production, climate analysis, computational chemistry, and bioinformatics have propelled computing systems toward the exascale: systems with 10 18 floating-point operations per second. These systems, to be designed and constructed over the next decade, will create unprecedented challenges in component counts, power consumption, resource limitations, and system complexity. Data storage and access are an increasingly important and complex component in extreme-scale computing systems, and significant design work is needed to develop successful storage hardware and software architectures at exascale. Co-design of these systems will be necessary to find the best possible design points for exascale systems. The goal of this work has been to enable the exploration and co-design of exascale storage systems by providing a detailed, accurate, and highly parallel simulation of exascale storage and the surrounding environment. Specifically, this simulation has (1) portrayed realistic application checkpointing and analysis workloads, (2) captured the complexity, scale, and multilayer nature of exascale storage hardware and software, and (3) executed in a timeframe that enables “what if'” exploration of design concepts. We developed models of the major hardware and software components in an exascale storage system, as well as the application I/O workloads that drive them. We used our simulation system to investigate critical questions in reliability and concurrency at exascale, helping guide the design of future exascale hardware and software architectures. Additionally, we provided this system to interested vendors and researchers so that others can explore the design space. We validated the capabilities of our simulation environment by configuring the simulation to represent the Argonne Leadership Computing Facility Blue Gene/Q system and comparing simulation results for application I/O patterns to the results of executions of these I/O kernels on the actual system.
Vertical-axis wind turbines (VAWTs) have a long history, with a wide variety of turbine archetypes that have been designed and tested since the 1970s. While few utility-scale VAWTs currently exist, the placement of the generator near the turbine base could make VAWTs advantageous over tradition horizontal-axis wind turbines for floating offshore wind applications via reduced platform costs and improved scaling potential. However, there are currently few numerical design and analysis tools available for VAWTs. One existing engineering toolset for aero-hydro-servo-elastic simulation of VAWTs is the Offshore Wind ENergy Simulator (OWENS), but its current modeling capability for floating systems is non-standard and not ideal. This article describes how OWENS has been coupled to several OpenFAST modules to update and improve modeling of floating offshore VAWTs and discusses the verification of these new capabilities and features. The results of the coupled OWENS verification test agree well with a parallel OpenFAST simulation, validating the new modeling and simulation capabilities in OWENS for floating VAWT applications. These developments will enable the design and optimization of floating offshore VAWTs in the future.