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At least 1,531 records · Page 85

Automated management of power systems

APSM (Automated Power System Management) is a technology readiness program underway to develop, evaluate, and demonstrate various techniques involved in power system monitoring, as well as computational and control functions. The demonstration breadboard consists of the Viking Orbiter '75 power subassembly breadboard modified to incorporate dedicated microprocessors and digital interface circuits, as well as test support equipment for both spacecraft and ground computer simulation, fault simulation, and data acquisition.

Imamura, M. S.↗

Proceedings of the 1998 International Computational Accelerator Physics Conference

The 1998 International Computational Accelerator Physics Conference, ICAP’98, was held September 14-18, 1998, at the Monterey Convention Center in Monterey, California. The meeting continued the tradition of four earlier Computational Accelerator Physics conferences, held in La Jolla, California (1988), Los Alamos, New Mexico (1990), Pleasanton, California (1993), and Williamsburg, Virginia (1996). ICAP’98 was organized by the Stanford Linear Accelerator Center (SLAC), Los Alamos National Laboratory (LANL), and the National Energy Research Scientific Computing Center (NERSC), and received support from the U.S. Department of Energy. The aim of this conference series is to discuss recent advances in Computational Accelerator Physics and their applications to solving important problems related to present and future accelerators. The ICAP’98 program included plenary sessions on modeling challenges in next-generation accelerators, state-of-the art methods in computational accelerator physics, and a view of what high-end computing would be like in the 21st century. There were also focused sessions on accelerator design and control, modeling high intensity beam phenomena, electromagnetic modeling, advanced algorithms, software environments and libraries, visualization and graphic interfaces, modeling advanced accelerator concepts, modeling the beam-beam interaction, computing wakefields, and combined particle/field simulations. In addition to these oral sessions there was a poster session and a vendor display. Prior to the start of the technical program, a half-day tutorial on High Performance Computing was hosted by NERSC. The ICAP series recognizes that computing and, in particular, advanced computing, is playing an increasingly important role in the successful design and development of major accelerator facilities, and in research and development leading to advances in accelerator technology. We expect that this new emphasis on high-end computing will continue in future ICAP conferences.

Ko, Kwok↗

Finite element analysis of the effect of a non-planar solid-liquid interface on the lateral solute segregation during unidirectional solidification

The effect of solid-liquid interface shape on lateral solute segregation during steady-state unidirectional solidification of a binary mixture is calculated under the assumption of no convection in the liquid. A finite element technique is employed to compute the concentration field in the liquid and the lateral segregation in the solid with a curved boundary between the liquid and solid phases. The computational model is constructed assuming knowledge of the solid-liquid interface shape; no attempt is made to relate this shape to the thermal field. The influence of interface curvature on the lateral compositional variation is investigated over a range of system parameters including diffusivity, growth speed, distribution coefficient, and geometric factors of the system. In the limiting case of a slightly nonplanar interface, numerical results from the finite element technique are in good agreement with the analytical solutions of Coriell and Sekerka obtained by using linear theory. For the general case of highly non-planar interface shapes, the linear theory fails and the concentration field in the liquid as well as the lateral solute segregation in the solid can be calculated by using the finite element method.

Carlson, F. M.↗

An extension to V ORO ++ for multithreaded computation of Voronoi cells

V ORO ++ is a software library written in C++ for computing the Voronoi tessellation, a technique in computational geometry that is widely used for analyzing systems of particles. V ORO ++ was released in 2009 and is based on computing the Voronoi cell for each particle individually. Here, we take advantage of modern computer hardware, and extend the original serial version to allow for multithreaded computation of Voronoi cells via the OpenMP application programming interface. We test the performance of the code, and demonstrate that it can achieve parallel efficiencies greater than 95% in many cases. Further, the multithreaded extension follows standard OpenMP programming paradigms, allowing it to be incorporated into other programs. We provide an example of this using the VoroTop software library, performing a multithreaded Voronoi cell topology analysis of up to 102.4 million particles.

97 MATHEMATICS AND COMPUTING↗

Modelling parallel programs and multiprocessor architectures with AXE

AXE, An Experimental Environment for Parallel Systems, was designed to model and simulate for parallel systems at the process level. It provides an integrated environment for specifying computation models, multiprocessor architectures, data collection, and performance visualization. AXE is being used at NASA-Ames for developing resource management strategies, parallel problem formulation, multiprocessor architectures, and operating system issues related to the High Performance Computing and Communications Program. AXE's simple, structured user-interface enables the user to model parallel programs and machines precisely and efficiently. Its quick turn-around time keeps the user interested and productive. AXE models multicomputers. The user may easily modify various architectural parameters including the number of sites, connection topologies, and overhead for operating system activities. Parallel computations in AXE are represented as collections of autonomous computing objects known as players. Their use and behavior is described. Performance data of the multiprocessor model can be observed on a color screen. These include CPU and message routing bottlenecks, and the dynamic status of the software.

Yan, Jerry C.↗

Automation in teleoperation from a man-machine interface viewpoint

Teleoperation can be defined as the use of robotic devices having mobility, manipulative and some sensing capabilities, and remotely controlled by a human operator. The purpose of this paper is to discuss and exemplify technology issues related to the use of robots as man-extension or teleoperator systems in space. The main thrust of the paper is focused at research and development in the area of sensing- and computer-based automation from the viewpoint of man-machine interface devices and techniques. The objective of this R and D effort is to render space teleoperation efficient and safe through the use of devices and techniques which will permit integrated and task-level ('intelligent') two-way control communication between human operator and teleoperator machine in earth orbit.

Bejczy, A. K.↗

ALSSAT Version 6.0

Advanced Life Support Sizing Analysis Tool (ALSSAT) at the time of this reporting has been updated to version 6.0. A previous version was described in Tool for Sizing Analysis of the Advanced Life Support System (MSC- 23506), NASA Tech Briefs, Vol. 29, No. 12 (December 2005), page 43. To recapitulate: ALSSAT is a computer program for sizing and analyzing designs of environmental-control and life-support systems for spacecraft and surface habitats to be involved in exploration of Mars and the Moon. Of particular interest for analysis by ALSSAT are conceptual designs of advanced life-support (ALS) subsystems that utilize physicochemical and biological processes to recycle air and water and process human wastes to reduce the need of resource resupply. ALSSAT is a means of investigating combinations of such subsystems technologies featuring various alternative conceptual designs and thereby assisting in determining which combination is most cost-effective. ALSSAT version 6.0 has been improved over previous versions in several respects, including the following additions: an interface for reading sizing data from an ALS database, computational models of a redundant regenerative CO2 and Moisture Removal Amine Swing Beds (CAMRAS) for CO2 removal, upgrade of the Temperature & Humidity Control's Common Cabin Air Assembly to a detailed sizing model, and upgrade of the Food-management subsystem.

Yeh, Hue-Hsia↗

WHONDRS-GUI: a web application for global survey of surface water metabolites

Background The Worldwide Hydrobiogeochemistry Observation Network for Dynamic River Systems (WHONDRS) is a consortium that aims to understand complex hydrologic, biogeochemical, and microbial connections within river corridors experiencing perturbations such as dam operations, floods, and droughts. For one ongoing WHONDRS sampling campaign, surface water metabolite and microbiome samples are collected through a global survey to generate knowledge across diverse river corridors. Metabolomics analysis and a suite of geochemical analyses have been performed for collected samples through the Environmental Molecular Sciences Laboratory (EMSL). The obtained knowledge and data package inform mechanistic and data-driven models to enhance predictions of outcomes of hydrologic perturbations and watershed function, one of the most critical components in model-data integration. To support efforts of the multi-domain integration and make the ever-growing data package more accessible for researchers across the world, a Shiny/R Graphical User Interface (GUI) called WHONDRS-GUI was created. Results The web application can be run on any modern web browser without any programming or operational system requirements, thus providing an open, well-structured, discoverable dataset for WHONDRS. Together with a context-aware dynamic user interface, the WHONDRS-GUI has functionality for searching, compiling, integrating, visualizing and exporting different data types that can easily be used by the community. The web application and data package are available at https://data.ess-dive.lbl.gov/view/doi:10.15485/1484811 , which enables users to simultaneously obtain access to the data and code and to subsequently run the web app locally. The WHONDRS-GUI is also available for online use at Shiny Server ( https://xmlin.shinyapps.io/whondrs/ ).

59 BASIC BIOLOGICAL SCIENCES↗

Application of a dedicated micro-processor for automatic data acquisition of load strain and acoustic-emission data

This paper describes an automatic system for acquisition, logging and analysis of stress, strain and acoustic emission data. The complete system is a combination of several standard items of equipment and a newly developed intelligent data logger which has the capability to send data directly to a large scale computer for reduction and plotting. The data logging and all interfacing with peripheral equipment are accomplished using digital electronics. The heart of the system is a four-bit microprocessor and digital cassette tape unit. The system, which is controlled by instructions from a cathode ray tube terminal, has the capability to transmit data from the cassette unit to a large computer via a time sharing option. Typical results are presented for acoustic emission count rate and total count curves superimposed on stress-strain diagrams for boron/epoxy advanced composites.

Wilson, G. H.↗

Hyperspectral Microwave Atmospheric Sounder (HyMAS) Architecture and Design Accommodations

The Hyperspectral Microwave Atmospheric Sounder (HyMAS) is being developed at Lincoln Laboratories and accommodated by the Goddard Space Flight Center for a flight opportunity on a NASA research aircraft. The term "hyperspectral microwave" is used to indicate an all-weather sounding that performs equivalent to hyperspectral infrared sounders in clear air with vertical resolution of approximately 1 km. Deploying the HyMAS equipped scanhead with the existing Conical Scanning Microwave Imaging Radiometer (CoSMIR) shortens the path to a flight demonstration. Hyperspectral microwave is achieved through the use of independent RF antennas that sample the volume of the Earth s atmosphere through various levels of frequencies, thereby producing a set of dense, spaced vertical weighting functions. The simulations proposed for HyMAS 118/183-GHz system should yield surface precipitation rate and water path retrievals for small hail, soft hail, or snow pellets, snow, rainwater, etc. with accuracies comparable to those of the Advanced Technology Microwave Sounder. Further improvements in retrieval methodology (for example, polarization exploitation) are expected. The CoSMIR instrument is a packaging concept re-used on HyMAS to ease the integration features of the scanhead. The HyMAS scanhead will include an ultra-compact Intermediate Frequency Processor (IFP) module that is mounted inside the door to improve thermal management. The IFP is fabricated with materials made of Low-Temperature Co-fired Ceramic (LTCC) technology integrated with detectors, amplifiers, A/D conversion and data aggregation. The IFP will put out 52 channels of 16 bit data comprised of 4-9 channel data streams for temperature profiles and 2-8 channel streams for water vapor. With the limited volume of the existing CoSMIR scanhead and new HyMAS front end components, the HyMAS team at Goddard began preliminary layout work inside the new drum. Importing and re-using models of the shell, the scan head computer, and the slip rings developed for CoSMIR was the starting point. The next step was to modify the antenna faceplate to accommodate the dimensions of the three dual polarization Gaussian Optics Antenna (GOA) assemblies. Two mechanical concepts for the core technology, the hyperspectral IFP, were captured in a design tradeoff. Connector models considered minimum bend radii for the IFP analog connectors. Hyperspectral imaging is accomplished by strategically using a short wavelength intermediate frequency of 18-29 GHz, and thus reducing the size of components in the connection of the front end to the IFP. The SMK (2.92mm) Series connector will lay near the hinge line to minimize its flexing. The digital output of the IFP will use a Serial Peripheral Interface (SPI) that must be accommodated by the scan head computer. To make that computer more reliable, maintainable, and forward compatible with the 52 HyMAS channels, a testbed of the scan head, calibration, and archive computers and the PIC24 microprocessor that resides on the IFP is in development. The computers will be programmed using a new framework application called Interoperable Remote Component (IRC). This software allows flexibility to program computers that communicate with each other and can adapt easily to the emerging HyMAS requirements for data format, algorithms, and graphical user interface (GUI). It is expected that the CoSMIR instrument will cut over to the IRC after it is adapted on an updated CoSMIR testbed.

Hilliard, Lawrence↗

Computational study of Li 3 BO 3 and Li 3 BN 2 II: Stability analysis of pure phases and of model interfaces with Li anodes

Both Li 3 BO 3 and Li 3 BN 2 materials have promising properties for use in all solid-state batteries and other technologies dependent on electrolytes with significant ionic conductivity. As the second of a two-part study, the structural properties of Li 3 BO 3 and three reported phases of Li 3 BN 2 are investigated using first-principles modeling techniques. For alpha- Li 3 BN 2 , the tetragonal P4 2 / mnm structure reported in the literature is found to be unstable as evidenced by imaginary phonon modes near the M point of its Brillouin zone. Our simulations within the harmonic approximation suggest that the real α phase has the orthorhombic space group symmetry Pmmn formed with twice as many formula units and tiny adjustments of the equivalent lattice parameters and fractional coordinates. Extending the analysis of the Pmmn α- Li 3 BN 2 structure to the quasiharmonic approximation improves the agreement between the room-temperature x-ray pattern reported in the literature and the corresponding simulation results. In anticipation of the use of the monoclinic phases of Li 3 BO 3 and Li 3 BN 2 in Li ion conducting applications, chemical stability is investigated in terms of free-energy differences of possible decomposition and Li reaction processes, finding encouraging results. As further investigations of Li 3 BO 3 and β- Li 3 BN 2 as electrolyte or coating materials, particularly for use with Li metal anodes, idealized electrolyte/Li interfaces were investigated in terms of their geometric, energetic, and electronic properties. The results find the electrolyte/Li interfaces to be quite favorable, perhaps comparable to the pioneering LiPON/Li system.

36 MATERIALS SCIENCE↗

Human factors model concerning the man-machine interface of mining crewstations

The U.S. Bureau of Mines is developing a computer model to analyze the human factors aspect of mining machine operator compartments. The model will be used as a research tool and as a design aid. It will have the capability to perform the following: simulated anthropometric or reach assessment, visibility analysis, illumination analysis, structural analysis of the protective canopy, operator fatigue analysis, and computation of an ingress-egress rating. The model will make extensive use of graphics to simplify data input and output. Two dimensional orthographic projections of the machine and its operator compartment are digitized and the data rebuilt into a three dimensional representation of the mining machine. Anthropometric data from either an individual or any size population may be used. The model is intended for use by equipment manufacturers and mining companies during initial design work on new machines. In addition to its use in machine design, the model should prove helpful as an accident investigation tool and for determining the effects of machine modifications made in the field on the critical areas of visibility and control reach ability.

Rider, James P.↗

Friction damping of two-dimensional motion and its application in vibration control

This paper presents an approximate method for analyzing the two-dimensional friction contact problem so as to compute the dynamic response of a structure constrained by friction interfaces. The friction force at the joint is formulated based on the Coulomb model. The single-term harmonic balance scheme, together with the receptance approach of decoupling the effect of the friction force on the structure from those of the external forces has been utilized to obtain the steady state response. The computational efficiency and accuracy of the method are demonstrated by comparing the results with long-term time solutions.

Menq, C.-H.↗

Databases for LDEF results

One of the objectives of the team supporting the LDEF Systems and Materials Special Investigative Groups is to develop databases of experimental findings. These databases identify the hardware flown, summarize results and conclusions, and provide a system for acknowledging investigators, tracing sources of data, and future design suggestions. To date, databases covering the optical experiments, and thermal control materials (chromic acid anodized aluminum, silverized Teflon blankets, and paints) have been developed at Boeing. We used the Filemaker Pro software, the database manager for the Macintosh computer produced by the Claris Corporation. It is a flat, text-retrievable database that provides access to the data via an intuitive user interface, without tedious programming. Though this software is available only for the Macintosh computer at this time, copies of the databases can be saved to a format that is readable on a personal computer as well. Further, the data can be exported to more powerful relational databases, capabilities, and use of the LDEF databases and describe how to get copies of the database for your own research.

Bohnhoff-Hlavacek, Gail↗

Improving the Capabilities and Computational Efficiency of the RTE+RRTMGP Radiation Code (Final Report)

This report details progress on the RTE+RRTMGP radiation codes made during the period of performance. RTE+RRTMGP is a set of codes for computing radiative fluxes in planetary atmospheres. RRTMGP uses a k-distribution to provide an optical description (absorption and possibly Rayleigh optical depth) of the gaseous atmosphere, along with the relevant source functions, on a pre-determined spectral grid given temperatures, pressures, and gas concentration. RTE computes fluxes given spectrally-resolved optical descriptions and source functions. Spectrally-resolved fluxes are summarized (“reduced”) via a user extensible class. The initial release of the code and the design choices are described in Pincus et al. 2019; the codes are available on Github. Although RRTMGP was based on current (at the time) empirical spectroscopic data, RTE and RRTMGP were developed in large part to modernize software practices. The design focused on flexibility broadly interpreted: by separating code from data and allowing data to drive computation; in coupling to the host model (e.g. the coupling of clouds to radiative fluxes is user-controlled); with respect to programming languages (computational tasks are accessed via widely-compatible C interfaces); and with respect to hardware (the codes run on a range of CPU and GPU architectures). The code also puts an emphasis on modularity and clarity. RTE+RRTMGP v1.0 was released in September 20219. This award supported the evolution of the RTE+RRTMGP code base to support greater flexibility, accuracy, and efficiency.

54 ENVIRONMENTAL SCIENCES↗

Addressing hypertext design and conversion issues

Hypertext is a network of information units connected by relational links. A hypertext system is a configuration of hardware and software that presents a hypertext to users and allows them to manage and access the information that it contains. Hypertext is also a user interface concept that closely supports the ways that people use printed information. Hypertext concepts encourage modularity and the elimination of redundancy in data bases because information can be stored only once but viewed in any appropriate context. Hypertext is such a hot idea because it is an enabling technology in that workstations and personal computers finally provide enough local processing power for hypertext user interfaces.

Glusko, Robert J.↗

Solution and Interface Structure and Dynamics in Geochemistry: Gateway to Link Elementary Processes to Mineral Nucleation and Growth

Our understanding of the process of mineral nucleation is starting to evolve from the solely thermodynamical aspects in classical nucleation theory toward a mechanistic study of reactions influenced by solvation structures of ions and their dynamics. A knowledge of how these atomic and molecular interactions respond to changing solution composition and/or the nature of an interface will form a fundamental foundation to understand rate-limiting reactions and processes for nucleation and growth. Here, we review recent advances from multidisciplinary experimental and computational approaches of the structure and dynamics of aqueous solutions and mineral–liquid interfaces that will influence rates of nucleation (and growth behavior) both homogeneously in aqueous solutions and heterogeneously at mineral–liquid interfaces. Furthermore, these processes include structure (and extent) of solute clustering, solvent degrees of freedom, and the presence of noninnocent charge-balancing ions, all of which can drive the selectivity and exert control over nucleation mechanisms. Similar controlling reactions can also occur at interfaces with the added complexities of how solute ions interact with and assemble on surface sites and use different mechanisms from bulk solutes, such as lateral solvent exchanges between distinct surface sites. To gain a predictive understanding of nucleation chemistry, we emphasize several key knowledge gaps that will need to be addressed in this field and highlight the importance of combining computations and experiments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗