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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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All sources NASA NTRS DOE OSTI

DOE OSTI2019

Spectral Variability of Remotely Sensed Target Materials: Causes, Models, and Strategies for Mitigation and Robust Exploitation

Here, the purpose of this survey is to examine the major causes of spectral variability in target materials, survey some associated physical models, and discuss how hyper spectral analyses can be made more robust to this variability. Although there are many kinds of hyperspectral-image exploitation algorithms (e.g., classification, clustering, and unmixing) and virtually all of them are affected by spectral variability, we will concentrate on the problem of target detection and, more specifically, the detection, identification, and location of particular materials of interest.

42 ENGINEERING↗

DOE OSTI2018

Dependence of Multiparticle Processes on the Interaction-Region Size in Collisions of High-Energy Protons and Nuclei

The problem of the dependence of multiparticle reaction-product formation on the interactionregion size is considered both at cosmic-ray and accelerator energies. In cosmic rays, a comparative analysis of interactions induced by protons and light nuclei was performed on the basis of data obtained by the Stratosphere Collaboration. At accelerator energies, the problem was studied by employing data of the EMU Collaboration. The results revealed a substantial distinction between the production processes in these event groups. An analysis of interactions between light nuclei, (C, O, Ne) + (C/N/O); between intermediate and light nuclei, (Si, S) + (C/N/O); and between heavy nuclei, (Au, Pb) + (Ag/Br), showed that there is a sizable enhancement of fluctuations as the size of the interaction region becomes smaller. A sharp growth of multiplicity and pseudorapidity correlations in the most central interactions, (C, O, Ne) + (C/N/O), is interpreted as a manifestation of internal virtual alpha-particle clustering of light nuclei.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

NASA NTRS1999

KNBD: A Remote Kernel Block Server for Linux

I am developing a prototype of a Linux remote disk block server whose purpose is to serve as a lower level component of a parallel file system. Parallel file systems are an important component of high performance supercomputers and clusters. Although supercomputer vendors such as SGI and IBM have their own custom solutions, there has been a void and hence a demand for such a system on Beowulf-type PC Clusters. Recently, the Parallel Virtual File System (PVFS) project at Clemson University has begun to address this need (1). Although their system provides much of the functionality of (and indeed was inspired by) the equivalent file systems in the commercial supercomputer market, their system is all in user-space. Migrating their 10 services to the kernel could provide a performance boost, by obviating the need for expensive system calls. Thanks to Pavel Machek, the Linux kernel has provided the network block device (2) with kernels 2.1.101 and later. You can configure this block device to redirect reads and writes to a remote machine's disk. This can be used as a building block for constructing a striped file system across several nodes.

Becker, Jeff↗

DOE OSTI2016

A Distributed OpenCL Framework using Redundant Computation and Data Replication

Applications written solely in OpenCL or CUDA cannot execute on a cluster as a whole. Most previous approaches that extend these programming models to clusters are based on a common idea: designating a centralized host node and coordinating the other nodes with the host for computation. However, the centralized host node is a serious performance bottleneck when the number of nodes is large. In this paper, we propose a scalable and distributed OpenCL framework called SnuCL-D for large-scale clusters. SnuCL-D's remote device virtualization provides an OpenCL application with an illusion that all compute devices in a cluster are confined in a single node. To reduce the amount of control-message and data communication between nodes, SnuCL-D replicates the OpenCL host program execution and data in each node. We also propose a new OpenCL host API function and a queueing optimization technique that significantly reduce the overhead incurred by the previous centralized approaches. To show the effectiveness of SnuCL-D, we evaluate SnuCL-D with a microbenchmark and eleven benchmark applications on a large-scale CPU cluster and a medium-scale GPU cluster.

Kim, Junghyun↗

DOE OSTI2024

Compiler-Driven FPGA Virtualization with SYNERGY

FPGAs are increasingly common in modern applications, and cloud providers now support on-demand FPGA acceleration in datacenters. Applications in datacenters run on virtual infrastructure, where consolidation, multi-tenancy, and workload migration enable economies of scale that are fundamental to the provider's business. However, a general strategy for virtualizing FPGAs has yet to emerge. While manufacturers struggle with hardware-based approaches, we propose a compiler/runtime-based solution called Synergy. We show a compiler transformation for Verilog programs that produces code able to yield control to software atsub-clock-tickgranularity according to the semantics of the original program. Synergy uses this property to efficiently support core virtualization primitives: suspend and resume, program migration, and spatial/temporal multiplexing, on hardware which is availabletoday.We use Synergy to virtualize FPGA workloads across a cluster of Intel SoCs and Xilinx FPGAs on Amazon F1. The workloads require no modification, run within 3--4x of unvirtualized performance, and incur a modest increase in FPGA fabric usage.

Computer Science↗

DOE OSTI2017

Knife-ovirt

Knife-ovirt is code building on the chef, knife-cloud, fog, rbovirt projects that allows deployment of virtual machines on an ovirt cluster, and immediately bootstrap them into a chef managed infrastructure. (similar to knife-openstack project).

Source record↗

DOE OSTI2017

Knife-ovirt

Source record↗

DOE OSTI2018

Virtualization of the ATLAS software environment on a shared HPC system

The shared HPC cluster NEMO at the University of Freiburg has been made available to local ATLAS users through the provisioning of virtual machines incorporating the ATLAS software environment analogously to a WLCG center. This concept allows to run both data analysis and production on the HPC host system which is connected to the existing Tier2/Tier3 infrastructure. Schedulers of the two clusters were integrated in a dynamic, on-demand way. An automatically generated, fully functional virtual machine image provides access to the local user environment. The performance in the virtualized environment is evaluated for typical High-Energy Physics applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS1981

Results from the central Hyades survey

Results of a soft X-ray survey of the central 5 deg of the Hyades star cluster made with the Einstein Observatory Imaging Proportional Counter are presented. Virtually all of the late F and early G stars in the cluster were detected at an X-ray luminosity of greater than 10 to the 28.5 erg/sec, although only about 50% of the stars in the cluster as a whole were detected. Plots of X-ray luminosity against B-V index indicate that the typical solar-type star in the Hyades is emitting soft X-rays at a level approximately 30 times that of the active sun. Histograms of the X-ray to bolometric luminosity ratio reveal a gradual distinction between late A-early F stars, which are expected to possess little or no convective envelope, and solar-type (F8-G5) stars, with convective outer atmospheres. Results confirm the dependence of stellar coronal activity on rotation, and establish the prevalence of stellar coronae throughout the main sequence and the giant regions of the H-R diagram.

Stern, R. A.↗

NASA NTRS1996

Performance Evaluation in Network-Based Parallel Computing

Network-based parallel computing is emerging as a cost-effective alternative for solving many problems which require use of supercomputers or massively parallel computers. The primary objective of this project has been to conduct experimental research on performance evaluation for clustered parallel computing. First, a testbed was established by augmenting our existing SUNSPARCs' network with PVM (Parallel Virtual Machine) which is a software system for linking clusters of machines. Second, a set of three basic applications were selected. The applications consist of a parallel search, a parallel sort, a parallel matrix multiplication. These application programs were implemented in C programming language under PVM. Third, we conducted performance evaluation under various configurations and problem sizes. Alternative parallel computing models and workload allocations for application programs were explored. The performance metric was limited to elapsed time or response time which in the context of parallel computing can be expressed in terms of speedup. The results reveal that the overhead of communication latency between processes in many cases is the restricting factor to performance. That is, coarse-grain parallelism which requires less frequent communication between processes will result in higher performance in network-based computing. Finally, we are in the final stages of installing an Asynchronous Transfer Mode (ATM) switch and four ATM interfaces (each 155 Mbps) which will allow us to extend our study to newer applications, performance metrics, and configurations.

Dezhgosha, Kamyar↗

DOE OSTI2021

Quantum Solvers for Plane-Wave Hamiltonians: Abridging Virtual Spaces Through the Optimization of Pairwise Correlations

For many-body methods such as MCSCF and CASSCF, in which the number of one-electron orbitals is optimized and independent of the basis set used, there are no problems with using plane-wave basis sets. However, for methods currently used in quantum computing such as select configuration interaction (CI) and coupled cluster (CC) methods, it is necessary to have a virtual space that is able to capture a significant amount of electron-electron correlation in the system. The virtual orbitals in a pseudopotential plane-wave Hartree–Fock calculation, because of Coulomb repulsion, are often scattering states that interact very weakly with the filled orbitals. As a result, very little correlation energy is captured from them. The use of virtual spaces derived from the one-electron operators has also been tried, and while some correlations are captured, the amount is quite low. To overcome these limitations, we have been developing new classes of algorithms to define virtual spaces by optimizing orbitals from small pairwise CI Hamiltonians, which we term as correlation optimized virtual orbitals with the abbreviation COVOs. With these procedures, we have been able to derive virtual spaces, containing only a few orbitals, which are able to capture a significant amount of correlation. The focus in this manuscript is on using these derived basis sets to target full CI (FCI) quality results for H2 on near-term quantum computers. However, the initial results for this approach were promising. We were able to obtain good agreement with FCI/cc-pVTZ results for this system with just 4 virtual orbitals, using both FCI and quantum simulations. The quality of the results using COVOs suggests that it may be possible to use them in other many-body approaches, including coupled cluster and Møller–Plesset perturbation theories, and open up the door to many-body calculations for pseudopotential plane-wave basis set methods.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

On lithium-rich red giants: engulfment on the giant branch of Trumpler 20

The Gaia-ESO survey recently reported on a large sample of lithium (Li) abundance determinations for evolved stars in the rich open cluster Trumpler 20. They argue for a scenario where virtually all stars experience post-main-sequence mixing and Li is preserved in only two objects. We present an alternate explanation, where Li is normal in the vast majority of cluster stars and anomalously high in these two cases. We demonstrate that the Li upper limits in the red giants can be explained with a combination of main-sequence depletion and standard dredge-up and that they are close to the detected levels in other systems of similar age. In our framework, two of the detected giants are anomalously Li-rich, and we propose that both could have been produced by the engulfment of a substellar mass companion of 16{sub −10}{sup +6} M{sub J}. This would imply that ∼5% of 1.8 M{sub ⊙} stars in this system, and by extension elsewhere, should have substellar mass companions of high mass that could be engulfed at some point in their lifetimes. We discuss future tests that could confirm or refute this scenario.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1993

A distributed version of the NASA Engine Performance Program

Distributed NEPP, a version of the NASA Engine Performance Program, uses the original NEPP code but executes it in a distributed computer environment. Multiple workstations connected by a network increase the program's speed and, more importantly, the complexity of the cases it can handle in a reasonable time. Distributed NEPP uses the public domain software package, called Parallel Virtual Machine, allowing it to execute on clusters of machines containing many different architectures. It includes the capability to link with other computers, allowing them to process NEPP jobs in parallel. This paper discusses the design issues and granularity considerations that entered into programming Distributed NEPP and presents the results of timing runs.

Cours, Jeffrey T.↗

DOE OSTI2015

ZFIRE: Galaxy cluster kinematics, Hα star formation rates, and gas phase metallicities of XMM-LSS J02182-05102 AT z{sub cl}=1.6233

We spectroscopically survey the galaxy cluster XMM-LSS J02182-05102 (hereafter IRC 0218) using LRIS (optical) and MOSFIRE (near-infrared) on Keck I as part of the ZFIRE survey. IRC 0218 has a narrow redshift range of 1.612 < z{sub spec} < 1.635 defined by 33 members of which 20 are at R{sub proj} < 1 Mpc. The cluster redshift and velocity dispersion are z{sub cl}=1.6233±0.0003 and σ{sub cl}=254±50 km s{sup −1}. We reach NIR line sensitivities of ∼0.3 × 10{sup −17} erg s{sup −1} cm{sup −2} that, combined with multi-wavelength photometry, provide extinction-corrected Hα star formation rates (SFR), gas phase metallicities from [N ii]/Hα, and stellar masses. We measure an integrated Hα SFR of ∼325 M{sub ⊙} yr{sup −1} (26 members; R{sub proj} < 2 Mpc) and show that the elevated star formation in the cluster core (R{sub proj} < 0.25 Mpc) is driven by the concentration of star-forming members, but the average SFR per Hα-detected galaxy is half that of members at R{sub proj} ∼ 1 Mpc. However, we do not detect any environmental imprint when comparing attenuation and gas phase metallicities: the cluster galaxies show similar trends with M{sub ⋆} as to the field, e.g., more massive galaxies have larger stellar attenuation. IRC 0218’s gas phase metallicity–M{sub ⋆} relation (MZR) is offset to lower metallicities relative to z∼0 and has a slope of 0.13 ± 0.10. Comparing the MZR in IRC 0218 to the COSMOS cluster at z = 2.1 shows no evolution (Δt∼1 Gyr): the MZR for both galaxy clusters are remarkably consistent with each other and virtually identical to several field surveys at z∼2.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2017

Three-Dimensional Modeling of Fracture Clusters in Geothermal Reservoirs

The objective of this is to develop a 3-D numerical model for simulating mode I, II, and III (tensile, shear, and out-of-plane) propagation of multiple fractures and fracture clusters to accurately predict geothermal reservoir stimulation using the virtual multi-dimensional internal bond (VMIB). Effective development of enhanced geothermal systems can significantly benefit from improved modeling of hydraulic fracturing. In geothermal reservoirs, where the temperature can reach or exceed 350oC, thermal and poro-mechanical processes play an important role in fracture initiation and propagation. In this project hydraulic fracturing of hot subsurface rock mass will be numerically modeled by extending the virtual multiple internal bond theory and implementing it in a finite element code, WARP3D, a three-dimensional finite element code for solid mechanics. The new constitutive model along with the poro-thermoelastic computational algorithms will allow modeling the initiation and propagation of clusters of fractures, and extension of pre-existing fractures. The work will enable the industry to realistically model stimulation of geothermal reservoirs. The project addresses the Geothermal Technologies Office objective of accurately predicting geothermal reservoir stimulation (GTO technology priority item). The project goal will be attained by: (i) development of the VMIB method for application to 3D analysis of fracture clusters; (ii) development of poro- and thermoelastic material sub-routines for use in 3D finite element code WARP3D; (iii) implementation of VMIB and the new material routines in WARP3D to enable simulation of clusters of fractures while accounting for the effects of the pore pressure, thermal stress and inelastic deformation; (iv) simulation of 3D fracture propagation and coalescence and formation of clusters, and comparison with laboratory compression tests; and (v) application of the model to interpretation of injection experiments (planned by our industrial partner) with reference to the impact of the variations in injection rate and temperature, rock properties, and in-situ stress.

15 GEOTHERMAL ENERGY↗

DOE OSTI2016

minimega v. 3.0

minimega is an emulytics platform for creating testbeds of networked devices. The platoform consists of easily deployable tools to facilitate bringing up large networks of virtual machines including Windows, Linux, and Android. minimega allows experiments to be brought up quickly with almost no configuration. minimega also includes tools for simple cluster, management, as well as tools for creating Linux-based virtual machines. This release of minimega includes new emulated sensors for Android devices to improve the fidelity of testbeds that include mobile devices. Emulated sensors include GPS and

Crussell, Jonathan↗

DOE OSTI2015

minimega v. 3.0

Crussell, Jonathan↗

NASA NTRS1992

The engine design engine. A clustered computer platform for the aerodynamic inverse design and analysis of a full engine

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.

Sanz, J.↗