WorldWideScience

Sample records for materials computational studies

  1. Computational studies of novel thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D J; Mazin, I I; Kim, S G; Nordstrom, L

    1997-07-01

    The thermoelectric properties of La-filled skutterdites and {beta}-Zn{sub 4}Sb{sub 3} are discussed from the point of view of their electronic structures. These are calculated from first principles within the local density approximation. The electronic structures are in turn used to determine transport related quantities, {beta}-Zn{sub 4}Sb{sub 3} is found to be metallic with a complex Fermi surface topology, which yields a non-trivial dependence of the Hall concentration on the band filling. Calculations of the variation with band filling are used to extract the carrier concentration from the experimental Hall number. At this band filling, which corresponds to 0.1 electrons per 22 atom unit cell, the authors calculate a Seebeck coefficient and temperature dependence in good agreement with the experimental value. The high Seebeck coefficients in a metallic material are remarkable, and arise because of the strong energy dependence of the Fermiology near the experimental band filling. Virtual crystal calculations for La(Fe,Co){sub 4}Sb{sub 12}. The valence band maximum occurs at the {Gamma} point and is due to a singly degenerate dispersive (Fe,Co)-Sb band, which by itself would not be favorable for TE. However, very flat transition metal derived bands occur in close proximity and become active as the doping level is increased, giving a non-trivial dependence of the properties on carrier concentration and explaining the favorable TE properties.

  2. Computational Study on Spirocyclic Compounds as Energetic Materials (I)

    Energy Technology Data Exchange (ETDEWEB)

    Seok, Won K. [Dongguk Univ., Seoul (Korea, Republic of)

    2014-04-15

    The molecular structures of 2,6-diaza-1,3,5,7-tetraoxaspiro heptane and its dinitro derivative, 2,6-dinitro-2,6-diaza-1,3,5,7-tetraoxaspiro heptane, were fully optimized without symmetry constraints at HF/6-31G level of theory. A bisected conformation with respect to the ring is preferred with a C{sub 2} symmetric structure. The density of each molecule in the crystalline state was estimated to 1.12 and 2.36 g/cm{sup 3} using PM3/VSTO-3G calculations from the molecular volume. The heat of formation was calculated for two compounds at the CBS-4M level of theory. The detonation parameters were computed using the EXPLO5 software: D = 6282 m/s, P{sub C-J} = 127 kbar for compound, D = 7871 m/s, P{sub C-J} = 307 kbar for compound, and D = 6975 m/s, P{sub C-J} = 170 kbar for 60% compound with 40% TNT. Specific impulse of compound 1 in aluminized formulation when used as monopropellants was very similar to that of the conventional ammonium perchlorate in the same formulation of aluminum.

  3. The Computational Materials Repository

    DEFF Research Database (Denmark)

    Landis, David D.; Hummelshøj, Jens S.; Nestorov, Svetlozar

    2012-01-01

    The possibilities for designing new materials based on quantum physics calculations are rapidly growing, but these design efforts lead to a significant increase in the amount of computational data created. The Computational Materials Repository (CMR) addresses this data challenge and provides...

  4. Study of Material Flow of End-of-Life Computer Equipment (e-wastes ...

    African Journals Online (AJOL)

    In this study, a material flow model for the analysis of e-waste generation from computer equipment in Kaduna and Abuja in Nigeria has been developed and compared with that of Lagos which has been studied earlier. Data used to develop the models are the sales data from major distributors of electronics in the study ...

  5. Computational materials design

    International Nuclear Information System (INIS)

    Snyder, R.L.

    1999-01-01

    Full text: Trial and error experimentation is an extremely expensive route to the development of new materials. The coming age of reduced defense funding will dramatically alter the way in which advanced materials have developed. In the absence of large funding we must concentrate on reducing the time and expense that the R and D of a new material consumes. This may be accomplished through the development of computational materials science. Materials are selected today by comparing the technical requirements to the materials databases. When existing materials cannot meet the requirements we explore new systems to develop a new material using experimental databases like the PDF. After proof of concept, the scaling of the new material to manufacture requires evaluating millions of parameter combinations to optimize the performance of the new device. Historically this process takes 10 to 20 years and requires hundreds of millions of dollars. The development of a focused set of computational tools to predict the final properties of new materials will permit the exploration of new materials systems with only a limited amount of materials characterization. However, to bound computational extrapolations, the experimental formulations and characterization will need to be tightly coupled to the computational tasks. The required experimental data must be obtained by dynamic, in-situ, very rapid characterization. Finally, to evaluate the optimization matrix required to manufacture the new material, very rapid in situ analysis techniques will be essential to intelligently monitor and optimize the formation of a desired microstructure. Techniques and examples for the rapid real-time application of XRPD and optical microscopy will be shown. Recent developments in the cross linking of the world's structural and diffraction databases will be presented as the basis for the future Total Pattern Analysis by XRPD. Copyright (1999) Australian X-ray Analytical Association Inc

  6. A portable grid-enabled computing system for a nuclear material study

    International Nuclear Information System (INIS)

    Tsujita, Yuichi; Arima, Tatsumi; Takekawa, Takayuki; Suzuki, Yoshio

    2010-01-01

    We have built a portable grid-enabled computing system specialized for our molecular dynamics (MD) simulation program to study Pu material easily. Experimental approach to reveal properties of Pu materials is often accompanied by some difficulties such as radiotoxicity of actinides. Since a computational approach reveals new aspects to researchers without such radioactive facilities, we address an MD computation. In order to have more realistic results about e.g., melting point or thermal conductivity, we need a large scale of parallel computations. Most of application users who don't have supercomputers in their institutes should use a remote supercomputer. For such users, we have developed the portable and secured grid-enabled computing system to utilize a grid computing infrastructure provided by Information Technology Based Laboratory (ITBL). This system enables us to access remote supercomputers in the ITBL system seamlessly from a client PC through its graphical user interface (GUI). Typically it enables seamless file accesses on the GUI. Furthermore monitoring of standard output or standard error is available to see progress of an executed program. Since the system provides fruitful functionalities which are useful for parallel computing on a remote supercomputer, application users can concentrate on their researches. (author)

  7. Computational Materials Repository

    DEFF Research Database (Denmark)

    Landis, David

    , different abstraction levels and enables users to analyze their own results, and allows to share data with collaborators. The approach of the Computational Materials Repository (CMR) is to convert data to an internal format that maintains the original variable names without insisting on any semantics...

  8. Computational Materials Science | Materials Science | NREL

    Science.gov (United States)

    Computational Materials Science Computational Materials Science An image of interconnecting, sphere science capabilities span many research fields and interests. Electronic, Optical, and Transport Properties of Photovoltaic Materials Material properties and defect physics of Si, CdTe, III-V, CIGS, CZTS

  9. A Comparative Study of Multi-material Data Structures for Computational Physics Applications

    Energy Technology Data Exchange (ETDEWEB)

    Garimella, Rao Veerabhadra [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Robey, Robert W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-31

    The data structures used to represent the multi-material state of a computational physics application can have a drastic impact on the performance of the application. We look at efficient data structures for sparse applications where there may be many materials, but only one or few in most computational cells. We develop simple performance models for use in selecting possible data structures and programming patterns. We verify the analytic models of performance through a small test program of the representative cases.

  10. Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study. Phase I

    Science.gov (United States)

    Thibeault, Sheila A.; Fay, Catharine C.; Lowther, Sharon E.; Earle, Kevin D.; Sauti, Godfrey; Kang, Jin Ho; Park, Cheol; McMullen, Amelia M.

    2012-01-01

    The key objectives of this study are to investigate, both computationally and experimentally, which forms, compositions, and layerings of hydrogen, boron, and nitrogen containing materials will offer the greatest shielding in the most structurally robust combination against galactic cosmic radiation (GCR), secondary neutrons, and solar energetic particles (SEP). The objectives and expected significance of this research are to develop a space radiation shielding materials system that has high efficacy for shielding radiation and that also has high strength for load bearing primary structures. Such a materials system does not yet exist. The boron nitride nanotube (BNNT) can theoretically be processed into structural BNNT and used for load bearing structures. Furthermore, the BNNT can be incorporated into high hydrogen polymers and the combination used as matrix reinforcement for structural composites. BNNT's molecular structure is attractive for hydrogen storage and hydrogenation. There are two methods or techniques for introducing hydrogen into BNNT: (1) hydrogen storage in BNNT, and (2) hydrogenation of BNNT (hydrogenated BNNT). In the hydrogen storage method, nanotubes are favored to store hydrogen over particles and sheets because they have much larger surface areas and higher hydrogen binding energy. The carbon nanotube (CNT) and BNNT have been studied as potentially outstanding hydrogen storage materials since 1997. Our study of hydrogen storage in BNNT - as a function of temperature, pressure, and hydrogen gas concentration - will be performed with a hydrogen storage chamber equipped with a hydrogen generator. The second method of introducing hydrogen into BNNT is hydrogenation of BNNT, where hydrogen is covalently bonded onto boron, nitrogen, or both. Hydrogenation of BN and BNNT has been studied theoretically. Hyper-hydrogenated BNNT has been theoretically predicted with hydrogen coverage up to 100% of the individual atoms. This is a higher hydrogen content

  11. Computing and Material

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette; Tamke, Martin

    2013-01-01

    The digital is often said to bring us away from material. The adverse is true: digital design and fabrication grants new interfaces towards material and allows architectural design to engage with material on architectural scale in a way that is further reaching than ever before....

  12. Introduction Of Computational Materials Science

    International Nuclear Information System (INIS)

    Lee, Jun Geun

    2006-08-01

    This book gives, descriptions of computer simulation, computational materials science, typical three ways of computational materials science, empirical methods ; molecular dynamics such as potential energy, Newton's equation of motion, data production and analysis of results, quantum mechanical methods like wave equation, approximation, Hartree method, and density functional theory, dealing of solid such as pseudopotential method, tight-binding methods embedded atom method, Car-Parrinello method and combination simulation.

  13. The microstructure of capsule containing self-healing materials: A micro-computed tomography study

    Energy Technology Data Exchange (ETDEWEB)

    Van Stappen, Jeroen, E-mail: Jeroen.Vanstappen@ugent.be [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Bultreys, Tom [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent (Belgium); Gilabert, Francisco A. [Mechanics of Materials and Structures, Dept. of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Zwijnaarde (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Hillewaere, Xander K.D. [Polymer Chemistry Research Group, Dept. of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Gómez, David Garoz [Mechanics of Materials and Structures, Dept. of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Zwijnaarde (Belgium); SIM vzw, Technologiepark 935, B-9052 Zwijnaarde (Belgium); Van Tittelboom, Kim [Magnel Laboratory for Concrete Research, Dept. of Structural Engineering, Ghent University, Technologiepark Zwijnaarde 904, B-9052 Ghent (Belgium); Dhaene, Jelle [UGCT/Radiation Physics, Dept. of Physics and Astronomy, Ghent University, Proeftuinstraat 86, B-9000 Ghent (Belgium); De Belie, Nele [Magnel Laboratory for Concrete Research, Dept. of Structural Engineering, Ghent University, Technologiepark Zwijnaarde 904, B-9052 Ghent (Belgium); Van Paepegem, Wim [Mechanics of Materials and Structures, Dept. of Materials Science and Engineering, Ghent University, Technologiepark Zwijnaarde 903, B-9052 Zwijnaarde (Belgium); Du Prez, Filip E. [Polymer Chemistry Research Group, Dept. of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000 Ghent (Belgium); Cnudde, Veerle [UGCT/PProGRess, Dept. of Geology, Ghent University, Krijgslaan 281 S8, B-9000 Ghent (Belgium)

    2016-09-15

    Autonomic self-healing materials are materials with built-in (micro-) capsules or vessels, which upon fracturing release healing agents in order to recover the material's physical and mechanical properties. In order to better understand and engineer these materials, a thorough characterization of the material's microstructural behavior is essential and often overlooked. In this context, micro-computed tomography (μCT) can be used to investigate the three dimensional distribution and (de)bonding of (micro-) capsules in their native state in a polymer system with self-healing properties. Furthermore, in-situ μCT experiments in a self-healing polymer and a self-healing concrete system can elucidate the breakage and leakage behavior of (micro-) capsules at the micrometer scale. While challenges related to image resolution and contrast complicate the characterization in specific cases, non-destructive 3D imaging with μCT is shown to contribute to the understanding of the link between the microstructure and the self-healing behavior of these complex materials. - Highlights: • μCT imaging allows for the analysis of microcapsule distribution patterns in self-healing materials. • μCT allows for qualitative and quantitative measurements of healing agent release from carriers in self-healing materials. • Experimental set-ups can be optimized by changing chemical compounds in the system to ensure maximum quality imaging.

  14. Computational approaches to energy materials

    CERN Document Server

    Catlow, Richard; Walsh, Aron

    2013-01-01

    The development of materials for clean and efficient energy generation and storage is one of the most rapidly developing, multi-disciplinary areas of contemporary science, driven primarily by concerns over global warming, diminishing fossil-fuel reserves, the need for energy security, and increasing consumer demand for portable electronics. Computational methods are now an integral and indispensable part of the materials characterisation and development process.   Computational Approaches to Energy Materials presents a detailed survey of current computational techniques for the

  15. HIGH-PERFORMANCE COMPUTING FOR THE STUDY OF EARTH AND ENVIRONMENTAL SCIENCE MATERIALS USING SYNCHROTRON X-RAY COMPUTED MICROTOMOGRAPHY

    International Nuclear Information System (INIS)

    FENG, H.; JONES, K.W.; MCGUIGAN, M.; SMITH, G.J.; SPILETIC, J.

    2001-01-01

    Synchrotron x-ray computed microtomography (CMT) is a non-destructive method for examination of rock, soil, and other types of samples studied in the earth and environmental sciences. The high x-ray intensities of the synchrotron source make possible the acquisition of tomographic volumes at a high rate that requires the application of high-performance computing techniques for data reconstruction to produce the three-dimensional volumes, for their visualization, and for data analysis. These problems are exacerbated by the need to share information between collaborators at widely separated locations over both local and tide-area networks. A summary of the CMT technique and examples of applications are given here together with a discussion of the applications of high-performance computing methods to improve the experimental techniques and analysis of the data

  16. HIGH-PERFORMANCE COMPUTING FOR THE STUDY OF EARTH AND ENVIRONMENTAL SCIENCE MATERIALS USING SYNCHROTRON X-RAY COMPUTED MICROTOMOGRAPHY.

    Energy Technology Data Exchange (ETDEWEB)

    FENG,H.; JONES,K.W.; MCGUIGAN,M.; SMITH,G.J.; SPILETIC,J.

    2001-10-12

    Synchrotron x-ray computed microtomography (CMT) is a non-destructive method for examination of rock, soil, and other types of samples studied in the earth and environmental sciences. The high x-ray intensities of the synchrotron source make possible the acquisition of tomographic volumes at a high rate that requires the application of high-performance computing techniques for data reconstruction to produce the three-dimensional volumes, for their visualization, and for data analysis. These problems are exacerbated by the need to share information between collaborators at widely separated locations over both local and tide-area networks. A summary of the CMT technique and examples of applications are given here together with a discussion of the applications of high-performance computing methods to improve the experimental techniques and analysis of the data.

  17. Material decomposition and virtual non-contrast imaging in photon counting computed tomography: an animal study

    Science.gov (United States)

    Gutjahr, R.; Polster, C.; Kappler, S.; Pietsch, H.; Jost, G.; Hahn, K.; Schöck, F.; Sedlmair, M.; Allmendinger, T.; Schmidt, B.; Krauss, B.; Flohr, T. G.

    2016-03-01

    The energy resolving capabilities of Photon Counting Detectors (PCD) in Computed Tomography (CT) facilitate energy-sensitive measurements. The provided image-information can be processed with Dual Energy and Multi Energy algorithms. A research PCD-CT firstly allows acquiring images with a close to clinical configuration of both the X-ray tube and the CT-detector. In this study, two algorithms (Material Decomposition and Virtual Non-Contrast-imaging (VNC)) are applied on a data set acquired from an anesthetized rabbit scanned using the PCD-CT system. Two contrast agents (CA) are applied: A gadolinium (Gd) based CA used to enhance contrasts for vascular imaging, and xenon (Xe) and air as a CA used to evaluate local ventilation of the animal's lung. Four different images are generated: a) A VNC image, suppressing any traces of the injected Gd imitating a native scan, b) a VNC image with a Gd-image as an overlay, where contrast enhancements in the vascular system are highlighted using colored labels, c) another VNC image with a Xe-image as an overlay, and d) a 3D rendered image of the animal's lung, filled with Xe, indicating local ventilation characteristics. All images are generated from two images based on energy bin information. It is shown that a modified version of a commercially available dual energy software framework is capable of providing images with diagnostic value obtained from the research PCD-CT system.

  18. The Effectiveness of Interactive Computer Assisted Modeling in Teaching Study Strategies and Concept Mapping of College Textbook Material.

    Science.gov (United States)

    Mikulecky, Larry

    A study evaluated the effectiveness of a series of print materials and interactive computer-guided study programs designed to lead undergraduate students to apply basic textbook reading and concept mapping strategies to the study of science and social science textbooks. Following field testing with 25 learning skills students, 50 freshman biology…

  19. Computational 2D Materials Database

    DEFF Research Database (Denmark)

    Rasmussen, Filip Anselm; Thygesen, Kristian Sommer

    2015-01-01

    We present a comprehensive first-principles study of the electronic structure of 51 semiconducting monolayer transition-metal dichalcogenides and -oxides in the 2H and 1T hexagonal phases. The quasiparticle (QP) band structures with spin-orbit coupling are calculated in the G(0)W(0) approximation...... and used as input to a 2D hydrogenic model to estimate exciton binding energies. Throughout the paper we focus on trends and correlations in the electronic structure rather than detailed analysis of specific materials. All the computed data is available in an open database......., and comparison is made with different density functional theory descriptions. Pitfalls related to the convergence of GW calculations for two-dimensional (2D) materials are discussed together with possible solutions. The monolayer band edge positions relative to vacuum are used to estimate the band alignment...

  20. Segmentation and quantification of materials with energy discriminating computed tomography: A phantom study

    International Nuclear Information System (INIS)

    Le, Huy Q.; Molloi, Sabee

    2011-01-01

    Purpose: To experimentally investigate whether a computed tomography (CT) system based on CdZnTe (CZT) detectors in conjunction with a least-squares parameter estimation technique can be used to decompose four different materials. Methods: The material decomposition process was divided into a segmentation task and a quantification task. A least-squares minimization algorithm was used to decompose materials with five measurements of the energy dependent linear attenuation coefficients. A small field-of-view energy discriminating CT system was built. The CT system consisted of an x-ray tube, a rotational stage, and an array of CZT detectors. The CZT array was composed of 64 pixels, each of which is 0.8x0.8x3 mm. Images were acquired at 80 kVp in fluoroscopic mode at 50 ms per frame. The detector resolved the x-ray spectrum into energy bins of 22-32, 33-39, 40-46, 47-56, and 57-80 keV. Four phantoms were constructed from polymethylmethacrylate (PMMA), polyethylene, polyoxymethylene, hydroxyapatite, and iodine. Three phantoms were composed of three materials with embedded hydroxyapatite (50, 150, 250, and 350 mg/ml) and iodine (4, 8, 12, and 16 mg/ml) contrast elements. One phantom was composed of four materials with embedded hydroxyapatite (150 and 350 mg/ml) and iodine (8 and 16 mg/ml). Calibrations consisted of PMMA phantoms with either hydroxyapatite (100, 200, 300, 400, and 500 mg/ml) or iodine (5, 15, 25, 35, and 45 mg/ml) embedded. Filtered backprojection and a ramp filter were used to reconstruct images from each energy bin. Material segmentation and quantification were performed and compared between different phantoms. Results: All phantoms were decomposed accurately, but some voxels in the base material regions were incorrectly identified. Average quantification errors of hydroxyapatite/iodine were 9.26/7.13%, 7.73/5.58%, and 12.93/8.23% for the three-material PMMA, polyethylene, and polyoxymethylene phantoms, respectively. The average errors for the four-material

  1. Nanocrystalline material in toroidal cores for current transformer: analytical study and computational simulations

    Directory of Open Access Journals (Sweden)

    Benedito Antonio Luciano

    2005-12-01

    Full Text Available Based on electrical and magnetic properties, such as saturation magnetization, initial permeability, and coercivity, in this work are presented some considerations about the possibilities of applications of nanocrystalline alloys in toroidal cores for current transformers. It is discussed how the magnetic characteristics of the core material affect the performance of the current transformer. From the magnetic characterization and the computational simulations, using the finite element method (FEM, it has been verified that, at the typical CT operation value of flux density, the nanocrystalline alloys properties reinforce the hypothesis that the use of these materials in measurement CT cores can reduce the ratio and phase errors and can also improve its accuracy class.

  2. Integrated Computational study of Material Lifetime in a Fusion Reactor Environment

    Energy Technology Data Exchange (ETDEWEB)

    Gilbert, M.; Dudarev, S.; Packer, L.; Zheng, S.; Sublet, J.-C., E-mail: mark.gilbert@ccfe.ac.uk [EURATOM/CCFE Fusion Association, Culham Centre for Fusion Energy, Abingdon (United Kingdom)

    2012-09-15

    Full text: The high-energy, high-intensity neutron fluxes produced by the fusion plasma will have a significant life-limiting impact on reactor components in both experimental and commercial fusion devices. Not only do the neutrons bombarding the materials induce atomic displacement cascades, leading to the accumulation of structural defects, but they also initiate nuclear reactions, which cause transmutation of the elemental atoms. Understanding the implications associated with the resulting compositional changes is one of the key outstanding issues related to fusion energy research. Several complimentary computational techniques have been used to investigate the problem. Firstly, neutron-transport simulations, performed on a reference design for the demonstration fusion power plant (DEMO), quantify the variation in neutron irradiation conditions as a function of geometry. The resulting neutron fluxes and spectra are then used as input into inventory calculations, which allow for the compositional changes of a material to be tracked in time. These calculations reveal that the production of helium (He) gas atoms, whose presence in a material is of particular concern because it can accumulate and cause swelling and embrittlement, will vary significantly, even within the same component of a reactor. Lastly, a density-functional-based model for He-induced grain-boundary embrittlement has been developed to predict the life-limiting consequences associated with relatively low concentrations of He in materials situated at various locations in the DEMO structure. The results suggest that some important fusion materials may be significantly more susceptible to this type of failure than others. (author)

  3. Phase behaviour of macromolecular liquid crystalline materials. Computational studies at the molecular level

    International Nuclear Information System (INIS)

    Stimson, Lorna M.

    2003-01-01

    Molecular simulations provide an increasingly useful insight into the static and dynamic characteristics of materials. In this thesis molecular simulations of macro-molecular liquid crystalline materials are reported. The first liquid crystalline material that has been investigated is a side chain liquid crystal polymer (SCLCP). In this study semi-atomistic molecular dynamics simulations have been conducted at a range of temperatures and an aligning potential has been applied to mimic the effect of a magnetic field. In cooling the SCLCP from an isotropic melt, microphase separation was observed yielding a domain structure. The application of a magnetic field to this structure aligns the domains producing a stable smectic mesophase. This is the first study in which mesophases have been observed using an off-lattice model of a SCLCP. The second material that has been investigated is a dendrimer with terminal mesogenic functionalization. Here, a multi-scale approach has been taken with Monte Carlo studies of a single dendrimer molecule in the gas phase at the atomistic level, semi-atomistic molecular dynamics of a single molecule in liquid crystalline solvents and a coarse-grained molecular dynamics study of the dendrimer in the bulk. The coarse-grained model has been developed and parameterized using the results of the atomistic and semi-atomistic work. The single molecule studies showed that the liquid crystalline dendrimer was able to change its structure by conformational changes in the flexible chains that link the mesogenic groups to the core. Structural change was seen under the application of a mean field ordering potential in the gas phase, and in the presence of liquid crystalline solvents. No liquid crystalline phases were observed for the bulk phase studies of the coarse-grained model. However, when the length of the mesogenic units was increased there was some evidence for microphase separation in these systems. (author)

  4. Theoretical and Computational Studies of Rare Earth Substitutes: A Test-bed for Accelerated Materials Development

    Energy Technology Data Exchange (ETDEWEB)

    Benedict, Lorin X. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    Hard permanent magnets in wide use typically involve expensive Rare Earth elements. In this effort, we investigated candidate permanent magnet materials which contain no Rare Earths, while simultaneously exploring improvements in theoretical methodology which enable the better prediction of magnetic properties relevant for the future design and optimization of permanent magnets. This included a detailed study of magnetocrystalline anisotropy energies, and the use of advanced simulation tools to better describe magnetic properties at elevated temperatures.

  5. Natural Carbonized Sugar as a Low-Temperature Ammonia Sensor Material: Experimental, Theoretical, and Computational Studies.

    Science.gov (United States)

    Ghule, Balaji G; Shaikh, Shoyebmohamad; Ekar, Satish U; Nakate, Umesh T; Gunturu, Krishna Chaitanya; Shinde, Nanasaheb M; Naushad, Mu; Kim, Kwang Ho; O'Dwyer, Colm; Mane, Rajaram S

    2017-12-13

    Carbonized sugar (CS) has been synthesized via microwave-assisted carbonization of market-quality tabletop sugar bearing in mind the advantages of this synthesis method, such as being useful, cost-effective, and eco-friendly. The as-prepared CS has been characterized for its morphology, phase purity, type of porosity, pore-size distribution, and so on. The gas-sensing properties of CS for various oxidizing and reducing gases are demonstrated at ambient temperature, where we observe good selectivity toward liquid ammonia among other gases. The highest ammonia response (50%) of a CS-based sensor was noted at 80 °C for 100 ppm concentration. The response and recovery times of the CS sensor are 180 and 216 s, respectively. This unveiling ammonia-sensing study is explored through a plausible theoretical mechanism, which is further well-supported by computational modeling performed using density function theory. The effect of relative humidity on the CS sensor has also been studied at ambient temperature, which demonstrated that the minimum and maximum (20-100%) relative humidity values revealed 16 and 62% response, respectively.

  6. Computational study on the behaviors of granular materials under mechanical cycling

    International Nuclear Information System (INIS)

    Wang, Xiaoliang; Ye, Minyou; Chen, Hongli

    2015-01-01

    Considering that fusion pebble beds are probably subjected to the cyclic compression excitation in their future applications, we presented a computational study to report the effect of mechanical cycling on the behaviors of granular matter. The correctness of our numerical experiments was confirmed by a comparison with the effective medium theory. Under the cyclic loads, the fast granular compaction was observed to evolve in a stretched exponential law. Besides, the increasing stiffening in packing structure, especially the decreasing moduli pressure dependence due to granular consolidation, was also observed. For the force chains inside the pebble beds, both the internal force distribution and the spatial distribution of force chains would become increasingly uniform as the external force perturbation proceeded and therefore produced the stress relief on grains. In this case, the originally proposed 3-parameter Mueth function was found to fail to describe the internal force distribution. Thereby, its improved functional form with 4 parameters was proposed here and proved to better fit the data. These findings will provide more detailed information on the pebble beds for the relevant fusion design and analysis

  7. Computational materials chemistry for carbon capture using porous materials

    International Nuclear Information System (INIS)

    Sharma, Abhishek; Malani, Ateeque; Huang, Runhong; Babarao, Ravichandar

    2017-01-01

    Control over carbon dioxide (CO 2 ) release is extremely important to decrease its hazardous effects on the environment such as global warming, ocean acidification, etc. For CO 2 capture and storage at industrial point sources, nanoporous materials offer an energetically viable and economically feasible approach compared to chemisorption in amines. There is a growing need to design and synthesize new nanoporous materials with enhanced capability for carbon capture. Computational materials chemistry offers tools to screen and design cost-effective materials for CO 2 separation and storage, and it is less time consuming compared to trial and error experimental synthesis. It also provides a guide to synthesize new materials with better properties for real world applications. In this review, we briefly highlight the various carbon capture technologies and the need of computational materials design for carbon capture. This review discusses the commonly used computational chemistry-based simulation methods for structural characterization and prediction of thermodynamic properties of adsorbed gases in porous materials. Finally, simulation studies reported on various potential porous materials, such as zeolites, porous carbon, metal organic frameworks (MOFs) and covalent organic frameworks (COFs), for CO 2 capture are discussed. (topical review)

  8. Data mining for materials design: A computational study of single molecule magnet

    Energy Technology Data Exchange (ETDEWEB)

    Dam, Hieu Chi [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Faculty of Physics, Vietnam National University, 334 Nguyen Trai, Hanoi (Viet Nam); Pham, Tien Lam; Ho, Tu Bao [Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan); Nguyen, Anh Tuan [Faculty of Physics, Vietnam National University, 334 Nguyen Trai, Hanoi (Viet Nam); Nguyen, Viet Cuong [HPC Systems, Inc., 3-9-15 Kaigan, Minato-ku, Tokyo 108-0022 (Japan)

    2014-01-28

    We develop a method that combines data mining and first principles calculation to guide the designing of distorted cubane Mn{sup 4+} Mn {sub 3}{sup 3+} single molecule magnets. The essential idea of the method is a process consisting of sparse regressions and cross-validation for analyzing calculated data of the materials. The method allows us to demonstrate that the exchange coupling between Mn{sup 4+} and Mn{sup 3+} ions can be predicted from the electronegativities of constituent ligands and the structural features of the molecule by a linear regression model with high accuracy. The relations between the structural features and magnetic properties of the materials are quantitatively and consistently evaluated and presented by a graph. We also discuss the properties of the materials and guide the material design basing on the obtained results.

  9. Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study

    Data.gov (United States)

    National Aeronautics and Space Administration — The objectives of the proposed research are to develop a space radiation shielding material system that has high efficacy for shielding radiation and also has high...

  10. Computer-supported resolution of measurement conflicts: a case-study in materials science

    NARCIS (Netherlands)

    de Jong, Hidde; Mars, Nicolaas; van der Vet, P.E.

    1999-01-01

    Resolving conflicts between different measurements ofa property of a physical system may be a key step in a discovery process. With the emergence of large-scale databases and knowledge bases with property measurements, computer support for the task of conflict resolution has become highly desirable.

  11. Computational and Experimental Study of Energetic Materials in a Counterflow Microgravity Environment

    Science.gov (United States)

    Takahashi, Fumiaki (Technical Monitor); Urban, David (Technical Monitor); Smooke, M. D.; Parr, T. P.; Hanson-Parr, D. M.; Yetter, R. A.; Risha, G.

    2004-01-01

    thermal wave penetration into the liquid, these experiments were found feasible, but not used for obtaining quantitative data. Microgravity experiments are needed to eliminate the dripping and boiling phenomena of these systems at normal gravity. Microgravity tests in the NASA Glenn 2.2 second drop tower were performed (1) to demonstrate the feasibility of performing propellant experiments using the NASA Glenn microgravity facilities, (2) to develop the operational procedures for safe handing of the energetic materials and disposal of their toxic combustion by-products and (3) to obtain initial measurements of the AP burning rate and flame structure under microgravity conditions. Experiments were conducted on the CH4/AP system previously studied at normal gravity using a modified design of the counterflow burner and a NASA Glenn Pig Rig, i.e., one of the existing drop rigs for general-purpose usage. In these experiments, the AP burning rate was measured directly with a linear variable differential transducer (LVDT) and video imaging of the flame structure was recorded ignition was achieved by hot wires stretched across the AP surfaces. Initial drop tower combustion data show that with the same burner separation distance and flow conditions of the normal gravity experiments, the AP burning rate is approximately a factor of two lower. This difference is likely a result of radiation effects, but further tests with longer test times need to be conducted to verify that steady state conditions were achieved under microgravity conditions.

  12. Computational Studies of CO 2 Sorption and Separation in an Ultramicroporous Metal–Organic Material

    KAUST Repository

    Forrest, Katherine A.

    2013-08-29

    Grand canonical Monte Carlo (GCMC) simulations of CO2 sorption and separation were performed in [Zn(pyz)2SiF6], a metal-organic material (MOM) consisting of a square grid of Zn2+ ions coordinated to pyrazine (pyz) linkers and pillars of SiF6 2- ions. This MOM was recently shown to have an unprecedented selectivity for CO2 over N2, CH4, and H 2 under industrially relevant conditions. The simulated CO 2 sorption isotherms and calculated isosteric heat of adsorption, Qst, values were in excellent agreement with the experimental data for all the state points considered. CO2 saturation in [Zn(pyz) 2SiF6] was achieved at near-ambient temperatures and pressures lower than 1.0 atm. Moreover, the sorbed CO2 molecules were representative of a liquid/fluid under such conditions as confirmed through calculating the isothermal compressibility, βT, values. The simulated CO2 uptakes within CO2/N2 (10:90), CO2/CH4 (50:50), and CO2/H2 (30:70) mixture compositions, characteristic of flue gas, biogas, and syngas, respectively, were comparable to those that were produced in the single-component CO2 sorption simulations. The modeled structure at saturation revealed a loading of 1 CO2 molecule per unit cell. The favored CO2 sorption site was identified as the attraction of the carbon atoms of CO2 molecules to four equatorial fluorine atoms of SiF6 2- anions simultaneously, resulting in CO2 molecules localized at the center of the channel. Furthermore, experimental studies have shown that [Zn(pyz)2SiF6] sorbed minimal amounts of CO2 and N2 at their respective liquid temperatures. Analysis of the crystal structure at 100 K revealed that the unit cell undergoes a slight contraction in all dimensions and contains pyrazine rings that are mildly slanted with an angle of 13.9. Additionally, molecular dynamics (MD) simulations revealed that the sorbate molecules are anchored to the framework at low temperatures, which inhibits diffusion. Thus, it is hypothesized that the sorbed molecules

  13. Computational Mechanics for Heterogeneous Materials

    Energy Technology Data Exchange (ETDEWEB)

    Lechman, Jeremy B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Baczewski, Andrew David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bond, Stephen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Erikson, William W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lehoucq, Richard B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mondy, Lisa Ann [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Noble, David R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pierce, Flint [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Roberts, Christine [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); van Swol, Frank B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yarrington, Cole [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-11-01

    The subject of this work is the development of models for the numerical simulation of matter, momentum, and energy balance in heterogeneous materials. These are materials that consist of multiple phases or species or that are structured on some (perhaps many) scale(s). By computational mechanics we mean to refer generally to the standard type of modeling that is done at the level of macroscopic balance laws (mass, momentum, energy). We will refer to the flow or flux of these quantities in a generalized sense as transport. At issue here are the forms of the governing equations in these complex materials which are potentially strongly inhomogeneous below some correlation length scale and are yet homogeneous on larger length scales. The question then becomes one of how to model this behavior and what are the proper multi-scale equations to capture the transport mechanisms across scales. To address this we look to the area of generalized stochastic process that underlie the transport processes in homogeneous materials. The archetypal example being the relationship between a random walk or Brownian motion stochastic processes and the associated Fokker-Planck or diffusion equation. Here we are interested in how this classical setting changes when inhomogeneities or correlations in structure are introduced into the problem. Aspects of non-classical behavior need to be addressed, such as non-Fickian behavior of the mean-squared-displacement (MSD) and non-Gaussian behavior of the underlying probability distribution of jumps. We present an experimental technique and apparatus built to investigate some of these issues. We also discuss diffusive processes in inhomogeneous systems, and the role of the chemical potential in diffusion of hard spheres is considered. Also, the relevance to liquid metal solutions is considered. Finally we present an example of how inhomogeneities in material microstructure introduce fluctuations at the meso-scale for a thermal conduction problem

  14. Computer simulations applied in materials

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    This workshop takes stock of the simulation methods applied to nuclear materials and discusses the conditions in which these methods can predict physical results when no experimental data are available. The main topic concerns the radiation effects in oxides and includes also the behaviour of fission products in ceramics, the diffusion and segregation phenomena and the thermodynamical properties under irradiation. This document brings together a report of the previous 2002 workshop and the transparencies of 12 presentations among the 15 given at the workshop: accommodation of uranium and plutonium in pyrochlores; radiation effects in La{sub 2}Zr{sub 2}O{sub 7} pyrochlores; first principle calculations of defects formation energies in the Y{sub 2}(Ti,Sn,Zr){sub 2}O{sub 7} pyrochlore system; an approximate approach to predicting radiation tolerant materials; molecular dynamics study of the structural effects of displacement cascades in UO{sub 2}; composition defect maps for A{sup 3+}B{sup 3+}O{sub 3} perovskites; NMR characterization of radiation damaged materials: using simulation to interpret the data; local structure in damaged zircon: a first principle study; simulation studies on SiC; insertion and diffusion of He in 3C-SiC; a review of helium in silica; self-trapped holes in amorphous silicon dioxide: their short-range structure revealed from electron spin resonance and optical measurements and opportunities for inferring intermediate range structure by theoretical modelling. (J.S.)

  15. Computer simulations applied in materials

    International Nuclear Information System (INIS)

    2003-01-01

    This workshop takes stock of the simulation methods applied to nuclear materials and discusses the conditions in which these methods can predict physical results when no experimental data are available. The main topic concerns the radiation effects in oxides and includes also the behaviour of fission products in ceramics, the diffusion and segregation phenomena and the thermodynamical properties under irradiation. This document brings together a report of the previous 2002 workshop and the transparencies of 12 presentations among the 15 given at the workshop: accommodation of uranium and plutonium in pyrochlores; radiation effects in La 2 Zr 2 O 7 pyrochlores; first principle calculations of defects formation energies in the Y 2 (Ti,Sn,Zr) 2 O 7 pyrochlore system; an approximate approach to predicting radiation tolerant materials; molecular dynamics study of the structural effects of displacement cascades in UO 2 ; composition defect maps for A 3+ B 3+ O 3 perovskites; NMR characterization of radiation damaged materials: using simulation to interpret the data; local structure in damaged zircon: a first principle study; simulation studies on SiC; insertion and diffusion of He in 3C-SiC; a review of helium in silica; self-trapped holes in amorphous silicon dioxide: their short-range structure revealed from electron spin resonance and optical measurements and opportunities for inferring intermediate range structure by theoretical modelling. (J.S.)

  16. Computational Study on Substituted s-Triazine Derivatives as Energetic Materials

    Directory of Open Access Journals (Sweden)

    Vikas D. Ghule

    2012-01-01

    Full Text Available s-Triazine is the essential candidate of many energetic compounds due to its high nitrogen content, enthalpy of formation and thermal stability. The present study explores s-triazine derivatives in which different -NO2, -NH2 and -N3 substituted azoles are attached to the triazine ring via C-N linkage. The density functional theory is used to predict geometries, heats of formation and other energetic properties. Among the designed compounds, -N3 derivatives show very high heats of formation. The densities for designed compounds were predicted by using the crystal packing calculations. Introduction of -NO2 group improves density as compared to -NH2 and -N3, their order of increasing density can be given as NO2>N3>NH2. Analysis of the bond dissociation energies for C-NO2, C-NH2 and C-N3 bonds indicates that substitutions of the -N3 and -NH2 group are favorable for enhancing the thermal stability of s-triazine derivatives. The nitro and azido derivatives of triazine are found to be promising candidates for the synthetic studies.

  17. Computer programs of information processing of nuclear physical methods as a demonstration material in studying nuclear physics and numerical methods

    Science.gov (United States)

    Bateev, A. B.; Filippov, V. P.

    2017-01-01

    The principle possibility of using computer program Univem MS for Mössbauer spectra fitting as a demonstration material at studying such disciplines as atomic and nuclear physics and numerical methods by students is shown in the article. This program is associated with nuclear-physical parameters such as isomer (or chemical) shift of nuclear energy level, interaction of nuclear quadrupole moment with electric field and of magnetic moment with surrounded magnetic field. The basic processing algorithm in such programs is the Least Square Method. The deviation of values of experimental points on spectra from the value of theoretical dependence is defined on concrete examples. This value is characterized in numerical methods as mean square deviation. The shape of theoretical lines in the program is defined by Gaussian and Lorentzian distributions. The visualization of the studied material on atomic and nuclear physics can be improved by similar programs of the Mössbauer spectroscopy, X-ray Fluorescence Analyzer or X-ray diffraction analysis.

  18. DESIGN OF MANUAL MATERIAL HANDLING SYSTEM THROUGH COMPUTER AIDED ERGONOMICS: A CASE STUDY AT BDTSC TEXTILE FIRM

    Directory of Open Access Journals (Sweden)

    Amare Matebu

    2014-12-01

    Full Text Available Designing of lifting, pushing and pulling activities based on the physical and physiological capabilities of the operators is essential. The purpose of this study is to analyze manual material handling (MMH working posture of the operators using 3D Static Strength Prediction Program (3DSSPP software and to identify major areas causing long last injury of operators. The research has investigated the fit between the demands of tasks and the capabilities of operators. At the existing situations, the actual capabilities of operators have been computed with the help of 3DSSPP software and compared with NIOSH standards. Accordingly, operators' working posture is at an unacceptable position that exposes them for musculoskeletal disorders. Then, after the improvement of the design of MMH device (cart's roller, the result showed that the forces required by the operators to push and pull the sliver cans have been reduced from 931.77 Newton to 194.23 Newton. Furthermore, improvement of MMH cart's roller has reduced the awkward posture of operators and the risk of musculoskeletal disorders. The improved manual material handling design also saves about 1828.40 ETB per month for the company.

  19. Computer aided materials design; Keisanki zairyo sekkei

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The questionnaire survey on the computer aided materials design (CAMD), and the survey of current domestic and overseas software concerned were carried out to clarify developmental issues. The current elementary technology of CAMD was also surveyed to study its several problems caused with a progress of material design technology due to drastic diffusion of CAMD. This project aims at establishment of a new demanded software, computer chemistry, focusing attention on functional materials such as catalyst, polymer and non-linear electronic materials. Microscopic simulation technology was mainly surveyed in fiscal 1996. Although some fruitful results have been obtained in the fields of medical and agricultural chemicals, organic compounds, proteins, catalysts and electronic materials, such some problems are pointed out as `CAMD cannot handle an actual size of the target system` and `commercially available software are very expensive.` Reliable tool development as elementary technology, and the verification of its applications are thus required. Meso-dynamics, polymers, surface reaction and integrated technological environment attract users` attention. 27 refs., 16 figs., 2 tabs.

  20. Materials Frontiers to Empower Quantum Computing

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Antoinette Jane [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sarrao, John Louis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Richardson, Christopher [Laboratory for Physical Sciences, College Park, MD (United States)

    2015-06-11

    This is an exciting time at the nexus of quantum computing and materials research. The materials frontiers described in this report represent a significant advance in electronic materials and our understanding of the interactions between the local material and a manufactured quantum state. Simultaneously, directed efforts to solve materials issues related to quantum computing provide an opportunity to control and probe the fundamental arrangement of matter that will impact all electronic materials. An opportunity exists to extend our understanding of materials functionality from electronic-grade to quantum-grade by achieving a predictive understanding of noise and decoherence in qubits and their origins in materials defects and environmental coupling. Realizing this vision systematically and predictively will be transformative for quantum computing and will represent a qualitative step forward in materials prediction and control.

  1. Computational Amphiphilic Materials for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Naresh eThota

    2015-10-01

    Full Text Available Amphiphilic materials can assemble into a wide variety of morphologies and have emerged as a novel class of candidates for drug delivery. Along with a large number of experiments reported, computational studies have been also conducted in this field. At an atomistic/molecular level, computations can facilitate quantitative understanding of experimental observations and secure fundamental interpretation of underlying phenomena. This review summarizes the recent computational efforts on amphiphilic copolymers and peptides for drug delivery. Atom-resolution and time-resolved insights are provided from bottom-up to microscopically elucidate the mechanisms of drug loading/release, which are indispensable in the rational screening and design of new amphiphiles for high-efficacy drug delivery.

  2. Computer modelling of microporous materials

    NARCIS (Netherlands)

    Catlow, C.R.A.; Santen, van R.A.; Smit, B.

    2004-01-01

    Microporous materials, including both zeolites and aluminophosphates are amongst the most fascinating classes of materials, with wide ranging important applications in catalysis, gas separation and ion exchange. The breadth of the field has, moreover, been extended in the last ten years by the

  3. Crystal growth and computational materials science

    International Nuclear Information System (INIS)

    Jayakumar, S.; Ravindran, P.; Arun Kumar, R.; Sudarshan, C.

    2012-01-01

    The proceedings of the international conference on advanced materials discusses the advances being made in the area of single crystals, their preparation and device development from these crystals and details of the progress that is taking place in the computational field relating to materials science. Computational materials science makes use of advanced simulation tools and computer interfaces to develop a virtual platform which can provide a model for real-time experiments. This book includes selected papers in topics of crystal growth and computational materials science. We are confident that the new concepts and results presented will stimulate and enhance progress of research on crystal growth and computational materials science. Papers relevant to INIS are indexed separately

  4. Design and computation of modern engineering materials

    CERN Document Server

    Altenbach, Holm

    2014-01-01

     The idea of this monograph is to present the latest results related to design and computation of engineering materials and structures. The contributions cover the classical fields of mechanical, civil and materials engineering up to biomechanics and advanced materials processing and optimization. The materials and structures covered can be categorized into modern steels and titanium alloys, composite materials, biological and natural materials, material hybrids and modern joining technologies. Analytical modelling, numerical simulation, the application of state-of-the-art design tools and sophisticated experimental techniques are applied to characterize the performance of materials and to design and optimize structures in different fields of engineering applications.

  5. Computational materials science: Nanoscale plasticity

    DEFF Research Database (Denmark)

    Jacobsen, Karsten Wedel; Schiøtz, Jakob

    2002-01-01

    How does plastic deformation of polycrystalline materials with grain sizes less than 100 nm look at the atomic scale? A large-scale molecular dynamics simulation of nanocrystalline alluminium reveals some surprising behaviour.......How does plastic deformation of polycrystalline materials with grain sizes less than 100 nm look at the atomic scale? A large-scale molecular dynamics simulation of nanocrystalline alluminium reveals some surprising behaviour....

  6. Computational research on lithium ion battery materials

    Science.gov (United States)

    Tang, Ping

    Crystals of LiFePO4 and related materials have recently received a lot of attention due to their very promising use as cathodes in rechargeable lithium ion batteries. This thesis studied the electronic structures of FePO 4 and LiMPO4, where M=Mn, Fe, Co and Ni within the framework of density-functional theory. The first study compared the electronic structures of the LiMPO 4 and FePO4 materials in their electrochemically active olivine form, using the LAPW (linear augmented plane wave) method [1]. A comparison of results for various spin configurations suggested that the ferromagnetic configuration can serve as a useful approximation for studying general features of these systems. The partial densities of states for the LiMPO4 materials are remarkably similar to each other, showing the transition metal 3d states forming narrow bands above the O 2p band. By contrast, in absence of Li, the majority spin transition metal 3d states are well-hybridized with the O 2p band in FePO4. The second study compared the electronic structures of FePO4 in several crystal structures including an olivine, monoclinic, quartz-like, and CrVO4-like form [2,3]. For this work, in addition to the LAPW method, PAW (Projector Augmented Wave) [4], and PWscf (plane-wave pseudopotential) [5] methods were used. By carefully adjusting the computational parameters, very similar results were achieved for the three independent computational methods. Results for the relative stability of the four crystal structures are reported. In addition, partial densities of state analyses show qualitative information about the crystal field splittings and bond hybridizations and help rationalize the understanding of the electrochemical and stability properties of these materials.

  7. Computed tomography of radioactive objects and materials

    International Nuclear Information System (INIS)

    Sawicka, B.D.; Murphy, R.V.; Tosello, G.; Reynolds, P.W.; Romaniszyn, T.

    1990-01-01

    Computed tomography (CT) has been performed on a number of radioactive objects and materials. Several unique technical problems are associated with CT of radioactive specimens. These include general safety considerations, techniques to reduce background-radiation effects on CT images and selection criteria for the CT source to permit object penetration and to reveal accurate values of material density. In the present paper, three groups of experiments will be described, for objects with low, medium and high levels of radioactivity. CT studies on radioactive specimens will be presented. They include the following: (1) examination of individual ceramic reactor-fuel (uranium dioxide) pellets, (2) examination of fuel samples from the Three Mile Island reactor, (3) examination of a CANDU (CANada Deuterium Uranium: registered trademark) nuclear-fuel bundle which underwent a simulated loss-of-coolant accident resulting in high-temperature damage and (4) examination of a PWR nuclear-reactor fuel assembly. (orig.)

  8. SiC2 siligraphene as a promising anchoring material for lithium-sulfur batteries: a computational study

    Science.gov (United States)

    Zhao, Yuming; Zhao, Jingxiang; Cai, Qinghai

    2018-05-01

    The development of stable and effective anchoring materials to immobilize the soluble lithium polysulfide (Li2Sn) species for suppressing their shuttle effects is vital for the large-scale practical applications of lithium-sulfur (Li-S) batteries. Here, by means of density functional theory (DFT) computations, the potential applications of the experimentally available SiC2 siligraphene (g-SiC2) as an anchoring material of Li-S batteries are systemically investigated. Our results reveal that g-SiC2 exhibits remarkable but not strong binding strength for the soluble Li2Sn species due to the S-Si and Li-C interactions. Especially, the intactness of the Li2Sn species and the good conductance of g-SiC2 can be well preserved after anchoring the Li2Sn species. The further comparative research demonstrate that g-SiC2 is superior to other siligraphenes, enabling it to be a very promising material as an ideal anchoring material for the immobilization of soluble Li2Sn species to avoid their dissolution into electrolyte.

  9. Computational Screening of Energy Materials

    DEFF Research Database (Denmark)

    Pandey, Mohnish

    , it is the need of the hour to search for environmentally benign renewable energy resources. The biggest source of the renewable energy is our sun and the immense energy it provides can be used to power the whole planet. However, an efficient way to harvest the solar energy to meet all the energy demand has...... not been realized yet. A promising way to utilize the solar energy is the photon assisted water splitting. The process involves the absorption of sunlight with a semiconducting material (or a photoabsorber) and the generated electron-hole pair can be used to produce hydrogen by splitting the water. However...... an accurate description of the energies with the first-principle calculations. Therefore, along this line the accuracy and predictability of the Meta-Generalized Gradient Approximation functional with Bayesian error estimation is also assessed....

  10. Computational Nanotechnology Molecular Electronics, Materials and Machines

    Science.gov (United States)

    Srivastava, Deepak; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    This presentation covers research being performed on computational nanotechnology, carbon nanotubes and fullerenes at the NASA Ames Research Center. Topics cover include: nanomechanics of nanomaterials, nanotubes and composite materials, molecular electronics with nanotube junctions, kinky chemistry, and nanotechnology for solid-state quantum computers using fullerenes.

  11. Proceedings of computational methods in materials science

    International Nuclear Information System (INIS)

    Mark, J.E. Glicksman, M.E.; Marsh, S.P.

    1992-01-01

    The Symposium on which this volume is based was conceived as a timely expression of some of the fast-paced developments occurring throughout materials science and engineering. It focuses particularly on those involving modern computational methods applied to model and predict the response of materials under a diverse range of physico-chemical conditions. The current easy access of many materials scientists in industry, government laboratories, and academe to high-performance computers has opened many new vistas for predicting the behavior of complex materials under realistic conditions. Some have even argued that modern computational methods in materials science and engineering are literally redefining the bounds of our knowledge from which we predict structure-property relationships, perhaps forever changing the historically descriptive character of the science and much of the engineering

  12. Application of cluster computing in materials science

    International Nuclear Information System (INIS)

    Kuzmin, A.

    2006-01-01

    Solution of many problems in materials science requires that high performance computing (HPC) be used. Therefore, a cluster computer, Latvian Super-cluster (LASC), was constructed at the Institute of Solid State Physics of the University of Latvia in 2002. The LASC is used for advanced research in the fields of quantum chemistry, solid state physics and nano materials. In this work we overview currently available computational technologies and exemplify their application by interpretation of x-ray absorption spectra for nano-sized ZnO. (author)

  13. Materials science. Materials that couple sensing, actuation, computation, and communication.

    Science.gov (United States)

    McEvoy, M A; Correll, N

    2015-03-20

    Tightly integrating sensing, actuation, and computation into composites could enable a new generation of truly smart material systems that can change their appearance and shape autonomously. Applications for such materials include airfoils that change their aerodynamic profile, vehicles with camouflage abilities, bridges that detect and repair damage, or robotic skins and prosthetics with a realistic sense of touch. Although integrating sensors and actuators into composites is becoming increasingly common, the opportunities afforded by embedded computation have only been marginally explored. Here, the key challenge is the gap between the continuous physics of materials and the discrete mathematics of computation. Bridging this gap requires a fundamental understanding of the constituents of such robotic materials and the distributed algorithms and controls that make these structures smart. Copyright © 2015, American Association for the Advancement of Science.

  14. Concealed nuclear material identification via combined fast-neutron/γ-ray computed tomography (FNGCT): a Monte Carlo study

    Science.gov (United States)

    Licata, M.; Joyce, M. J.

    2018-02-01

    The potential of a combined and simultaneous fast-neutron/γ-ray computed tomography technique using Monte Carlo simulations is described. This technique is applied on the basis of a hypothetical tomography system comprising an isotopic radiation source (americium-beryllium) and a number (13) of organic scintillation detectors for the production and detection of both fast neutrons and γ rays, respectively. Via a combination of γ-ray and fast neutron tomography the potential is demonstrated to discern nuclear materials, such as compounds comprising plutonium and uranium, from substances that are used widely for neutron moderation and shielding. This discrimination is achieved on the basis of the difference in the attenuation characteristics of these substances. Discrimination of a variety of nuclear material compounds from shielding/moderating substances (the latter comprising lead or polyethylene for example) is shown to be challenging when using either γ-ray or neutron tomography in isolation of one another. Much-improved contrast is obtained for a combination of these tomographic modalities. This method has potential applications for in-situ, non-destructive assessments in nuclear security, safeguards, waste management and related requirements in the nuclear industry.

  15. Potential of gadolinium as contrast material in second generation dual energy computed tomography - An ex vivo phantom study.

    Science.gov (United States)

    Bongers, Malte N; Schabel, Christoph; Krauss, Bernhard; Claussen, Claus D; Nikolaou, Konstantin; Thomas, Christoph

    To evaluate the potential of gadolinium (Gd) as contrast material (CM) in second generation dual energy computed tomography (DECT). In a phantom model, DECT post-processing was used to increase Gd attenuation using advanced monoenergetic extrapolation (MEI), to create virtual non-contrast images (Gd-VNC) and Gd maps and to quantify Gd content. Dilutions of Gd and iodinated CM (7-296 HU) were filled in syringes, placed in an attenuation phantom and scanned with standard DECT protocols (80 &100/Sn140 kV). MEI (40-190 keV) and VNC images as well as Gd maps were computed. The amount of Gd was quantified and the accuracy was compared to iodine images. Linear regression models were calculated to evaluate Gd attenuation of equivolume CM doses and clinical MRI doses. Applying monoenergetic reconstructions and using Gd as contrast agent (Gd MEI 40 keV) doubled Hounsfield-Units (HU) and 90% of the SNR (averaged: 225 HU, SNR3.1) are achievable, as compared to iodinated CM at 120 kV (averaged:110 HU, SNR3.5), at Gd doses of 1.0mmol/kg BW. The accuracies of Gd-VNC (deviation, 6±12 HU) images and Gd quantification (measurement error, 17%) were not significantly different to those of iodine enhanced images (VNC:deviation, 2±11 HU; measurement error,14%). Using monoenergetic extrapolation at 40keV, it is possible to increase Gd-CM attenuation significantly. Thus, equivalent HU and half the SNR in comparison to a standard dose of ICM at 120kV can be expected at a Gd-CM dose of 0.5mmol/kg BW. Post-processing features of iodine based DECT like monoenergetic or VNC images, iodine maps or quantification of CM are feasible with the use of Gd-CM. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Computational Materials Program for Alloy Design

    Science.gov (United States)

    Bozzolo, Guillermo

    2005-01-01

    The research program sponsored by this grant, "Computational Materials Program for Alloy Design", covers a period of time of enormous change in the emerging field of computational materials science. The computational materials program started with the development of the BFS method for alloys, a quantum approximate method for atomistic analysis of alloys specifically tailored to effectively deal with the current challenges in the area of atomistic modeling and to support modern experimental programs. During the grant period, the program benefited from steady growth which, as detailed below, far exceeds its original set of goals and objectives. Not surprisingly, by the end of this grant, the methodology and the computational materials program became an established force in the materials communitiy, with substantial impact in several areas. Major achievements during the duration of the grant include the completion of a Level 1 Milestone for the HITEMP program at NASA Glenn, consisting of the planning, development and organization of an international conference held at the Ohio Aerospace Institute in August of 2002, finalizing a period of rapid insertion of the methodology in the research community worlwide. The conference, attended by citizens of 17 countries representing various fields of the research community, resulted in a special issue of the leading journal in the area of applied surface science. Another element of the Level 1 Milestone was the presentation of the first version of the Alloy Design Workbench software package, currently known as "adwTools". This software package constitutes the first PC-based piece of software for atomistic simulations for both solid alloys and surfaces in the market.Dissemination of results and insertion in the materials community worldwide was a primary focus during this period. As a result, the P.I. was responsible for presenting 37 contributed talks, 19 invited talks, and publishing 71 articles in peer-reviewed journals, as

  17. Optimizing a reconfigurable material via evolutionary computation

    Science.gov (United States)

    Wilken, Sam; Miskin, Marc Z.; Jaeger, Heinrich M.

    2015-08-01

    Rapid prototyping by combining evolutionary computation with simulations is becoming a powerful tool for solving complex design problems in materials science. This method of optimization operates in a virtual design space that simulates potential material behaviors and after completion needs to be validated by experiment. However, in principle an evolutionary optimizer can also operate on an actual physical structure or laboratory experiment directly, provided the relevant material parameters can be accessed by the optimizer and information about the material's performance can be updated by direct measurements. Here we provide a proof of concept of such direct, physical optimization by showing how a reconfigurable, highly nonlinear material can be tuned to respond to impact. We report on an entirely computer controlled laboratory experiment in which a 6 ×6 grid of electromagnets creates a magnetic field pattern that tunes the local rigidity of a concentrated suspension of ferrofluid and iron filings. A genetic algorithm is implemented and tasked to find field patterns that minimize the force transmitted through the suspension. Searching within a space of roughly 1010 possible configurations, after testing only 1500 independent trials the algorithm identifies an optimized configuration of layered rigid and compliant regions.

  18. Advances in Integrated Computational Materials Engineering "ICME"

    Science.gov (United States)

    Hirsch, Jürgen

    The methods of Integrated Computational Materials Engineering that were developed and successfully applied for Aluminium have been constantly improved. The main aspects and recent advances of integrated material and process modeling are simulations of material properties like strength and forming properties and for the specific microstructure evolution during processing (rolling, extrusion, annealing) under the influence of material constitution and process variations through the production process down to the final application. Examples are discussed for the through-process simulation of microstructures and related properties of Aluminium sheet, including DC ingot casting, pre-heating and homogenization, hot and cold rolling, final annealing. New results are included of simulation solution annealing and age hardening of 6xxx alloys for automotive applications. Physically based quantitative descriptions and computer assisted evaluation methods are new ICME methods of integrating new simulation tools also for customer applications, like heat affected zones in welding of age hardening alloys. The aspects of estimating the effect of specific elements due to growing recycling volumes requested also for high end Aluminium products are also discussed, being of special interest in the Aluminium producing industries.

  19. Terahertz Computed Tomography of NASA Thermal Protection System Materials

    Science.gov (United States)

    Roth, D. J.; Reyes-Rodriguez, S.; Zimdars, D. A.; Rauser, R. W.; Ussery, W. W.

    2011-01-01

    A terahertz axial computed tomography system has been developed that uses time domain measurements in order to form cross-sectional image slices and three-dimensional volume renderings of terahertz-transparent materials. The system can inspect samples as large as 0.0283 cubic meters (1 cubic foot) with no safety concerns as for x-ray computed tomography. In this study, the system is evaluated for its ability to detect and characterize flat bottom holes, drilled holes, and embedded voids in foam materials utilized as thermal protection on the external fuel tanks for the Space Shuttle. X-ray micro-computed tomography was also performed on the samples to compare against the terahertz computed tomography results and better define embedded voids. Limits of detectability based on depth and size for the samples used in this study are loosely defined. Image sharpness and morphology characterization ability for terahertz computed tomography are qualitatively described.

  20. ICAN Computer Code Adapted for Building Materials

    Science.gov (United States)

    Murthy, Pappu L. N.

    1997-01-01

    The NASA Lewis Research Center has been involved in developing composite micromechanics and macromechanics theories over the last three decades. These activities have resulted in several composite mechanics theories and structural analysis codes whose applications range from material behavior design and analysis to structural component response. One of these computer codes, the Integrated Composite Analyzer (ICAN), is designed primarily to address issues related to designing polymer matrix composites and predicting their properties - including hygral, thermal, and mechanical load effects. Recently, under a cost-sharing cooperative agreement with a Fortune 500 corporation, Master Builders Inc., ICAN was adapted to analyze building materials. The high costs and technical difficulties involved with the fabrication of continuous-fiber-reinforced composites sometimes limit their use. Particulate-reinforced composites can be thought of as a viable alternative. They are as easily processed to near-net shape as monolithic materials, yet have the improved stiffness, strength, and fracture toughness that is characteristic of continuous-fiber-reinforced composites. For example, particlereinforced metal-matrix composites show great potential for a variety of automotive applications, such as disk brake rotors, connecting rods, cylinder liners, and other hightemperature applications. Building materials, such as concrete, can be thought of as one of the oldest materials in this category of multiphase, particle-reinforced materials. The adaptation of ICAN to analyze particle-reinforced composite materials involved the development of new micromechanics-based theories. A derivative of the ICAN code, ICAN/PART, was developed and delivered to Master Builders Inc. as a part of the cooperative activity.

  1. Polymorphs of LiFeSO4F as cathode materials for lithium ion batteries - a first principle computational study.

    Science.gov (United States)

    Chung, Sai Cheong; Barpanda, Prabeer; Nishimura, Shin-Ichi; Yamada, Yuki; Yamada, Atsuo

    2012-06-28

    We have investigated polymorphs of LiFeSO4F, tavorite and triplite, which have been reported as cathode materials for lithium ion batteries. The predicted voltages are 3.64 and 3.90 V for tavorite and triplite, respectively, which agreed excellently with experimental data. It is found that the lithiated states (LiFeSO4F) of the polymorphs are almost degenerate in energy. The difference in voltage is mainly due to the difference in the stabilities of the delithiated states (FeSO4F). This is rationalized by the Fe(3+)-Fe(3+) repulsion in the edge sharing geometry of the triplite structure.

  2. A Micro-Computed Tomography Technique to Study the Quality of Fibre Optics Embedded in Composite Materials

    Directory of Open Access Journals (Sweden)

    Gabriele Chiesura

    2015-05-01

    Full Text Available Quality of embedment of optical fibre sensors in carbon fibre-reinforced polymers plays an important role in the resultant properties of the composite, as well as for the correct monitoring of the structure. Therefore, availability of a tool able to check the optical fibre sensor-composite interaction becomes essential. High-resolution 3D X-ray Micro-Computed Tomography, or Micro-CT, is a relatively new non-destructive inspection technique which enables investigations of the internal structure of a sample without actually compromising its integrity. In this work the feasibility of inspecting the position, the orientation and, more generally, the quality of the embedment of an optical fibre sensor in a carbon fibre reinforced laminate at unit cell level have been proven.

  3. Experimental and computer simulation study of radionuclide yields in the ADT materials irradiated with intermediate energy protons

    Energy Technology Data Exchange (ETDEWEB)

    Titarenko, Yu.E.; Shvedov, O.V.; Batyaev, V.F. [Inst. for Theoretical and Experimental Physics, B. Cheremushkinskaya, Moscow (Russian Federation)] [and others

    1998-11-01

    The results of measurements and computer simulations of the yields of residual product nuclei in {sup 209}Bi, {sup 208,207,206,nat}Pb, {sup 65,63}Cu, {sup 59}Co thin targets irradiated by 0.13, 1.2 and 1.5 GeV protons are presented. The yields were measured by direct high-precision {gamma}-spectrometry. The process was monitored by the {sup 27}Al(p,x){sup 24}Na reaction. 801 cross sections are presented and used in comparisons between the reaction yields obtained experimentally and simulated by the HETC, GNASH, LAHET, INUCL, CEM95, CASCADE, NUCLEUS, YIELDX, QMD and ALICE codes. (author)

  4. Continuum mechanical and computational aspects of material behavior

    Energy Technology Data Exchange (ETDEWEB)

    Fried, Eliot; Gurtin, Morton E.

    2000-02-10

    The focus of the work is the application of continuum mechanics to materials science, specifically to the macroscopic characterization of material behavior at small length scales. The long-term goals are a continuum-mechanical framework for the study of materials that provides a basis for general theories and leads to boundary-value problems of physical relevance, and computational methods appropriate to these problems supplemented by physically meaningful regularizations to aid in their solution. Specific studies include the following: the development of a theory of polycrystalline plasticity that incorporates free energy associated with lattice mismatch between grains; the development of a theory of geometrically necessary dislocations within the context of finite-strain plasticity; the development of a gradient theory for single-crystal plasticity with geometrically necessary dislocations; simulations of dynamical fracture using a theory that allows for the kinking and branching of cracks; computation of segregation and compaction in flowing granular materials.

  5. Computational materials design for energy applications

    Science.gov (United States)

    Ozolins, Vidvuds

    2013-03-01

    General adoption of sustainable energy technologies depends on the discovery and development of new high-performance materials. For instance, waste heat recovery and electricity generation via the solar thermal route require bulk thermoelectrics with a high figure of merit (ZT) and thermal stability at high-temperatures. Energy recovery applications (e.g., regenerative braking) call for the development of rapidly chargeable systems for electrical energy storage, such as electrochemical supercapacitors. Similarly, use of hydrogen as vehicular fuel depends on the ability to store hydrogen at high volumetric and gravimetric densities, as well as on the ability to extract it at ambient temperatures at sufficiently rapid rates. We will discuss how first-principles computational methods based on quantum mechanics and statistical physics can drive the understanding, improvement and prediction of new energy materials. We will cover prediction and experimental verification of new earth-abundant thermoelectrics, transition metal oxides for electrochemical supercapacitors, and kinetics of mass transport in complex metal hydrides. Research has been supported by the US Department of Energy under grant Nos. DE-SC0001342, DE-SC0001054, DE-FG02-07ER46433, and DE-FC36-08GO18136.

  6. Li14P2O3N6 and Li7PN4: Computational study of two nitrogen rich crystalline LiPON electrolyte materials

    Science.gov (United States)

    Al-Qawasmeh, Ahmad; Holzwarth, N. A. W.

    2017-10-01

    Two lithium oxonitridophosphate materials are computationally examined and found to be promising solid electrolytes for possible use in all solid-state batteries having metallic Li anodes - Li14P2O3N6 and Li7PN4. The first principles simulations are in good agreement with the structural analyses reported in the literature for these materials and the computed total energies indicate that both materials are stable with respect to decomposition into binary and ternary products. The computational results suggest that both materials are likely to form metastable interfaces with Li metal. The simulations also find both materials to have Li ion migration activation energies comparable or smaller than those of related Li ion electrolyte materials. Specifically, for Li7PN4, the experimentally measured activation energy can be explained by the migration of a Li ion vacancy stabilized by a small number of O2- ions substituting for N3- ions. For Li14P2O3N6, the activation energy for Li ion migration has not yet been experimentally measured, but simulations predict it to be smaller than that measured for Li7PN4.

  7. Study of Neutron Induced Effects in Nuclear Materials by Computer Simulation: Ultra-Fast Solidification at the Nanoscopic Scale

    International Nuclear Information System (INIS)

    Lopasso, Edmundo

    2003-01-01

    In the present study we analyze some of the aspects on the primary damage induced by radiation in metals, specially Fe based alloys with low Cu content used in nuclear reactors.Atomic scale simulations with Molecular Dynamics and Monte Carlo methods were applied on the basis of interatomic potentials available in the literature. The Fe-Cu phase diagram was evaluated in the whole compositional range, and the phase and solubility limits as predicted by the model interactions were determined.Results, as compared to experimental findings, suggest that a better description of the potentials of the elements is needed, and that the description of the relative solubility of the solid phases should be included in the potentials.Even under these limitations, the solid-liquid phase limits in the Fe rich region are correctly represented, and the results are used to interpret the behaviour of Cu as solute in Fe during the cooling of displacement cascades.The analysis was performed with the aid of the results on the Ni-Au system, whose thermodynamic and solute transport properties are correctly described by interatomic potentials.This allowed us to separate the relative effects of thermal gradients and phase diagram characteristics on the solute redistribution.From the results on the Ni-Au system and dilute alloys of Cu in Fe, it is concluded that thermal gradients have an influence on solute redistribution, which migrate to the high temperature regions if the solute mass is lower than the solvent mass, while the opposite occurs if the solute mass is higher than the solvent one.This effect is known as thermomigration, and acts during the cooling down after the interaction of radiation with matter depending on the characteristic property known as heat of transport.By comparing different cooling rates in Ni-5%Au it is concluded that the phase diagram will have an effect on solute redistribution if the equilibrium partition ratio between the solidus and liquidus lines is low enough

  8. Separation of hepatic iron and fat by dual-source dual-energy computed tomography based on material decomposition: an animal study.

    Science.gov (United States)

    Ma, Jing; Song, Zhi-Qiang; Yan, Fu-Hua

    2014-01-01

    To explore the feasibility of dual-source dual-energy computed tomography (DSDECT) for hepatic iron and fat separation in vivo. All of the procedures in this study were approved by the Research Animal Resource Center of Shanghai Ruijin Hospital. Sixty rats that underwent DECT scanning were divided into the normal group, fatty liver group, liver iron group, and coexisting liver iron and fat group, according to Prussian blue and HE staining. The data for each group were reconstructed and post-processed by an iron-specific, three-material decomposition algorithm. The iron enhancement value and the virtual non-iron contrast value, which indicated overloaded liver iron and residual liver tissue, respectively, were measured. Spearman's correlation and one-way analysis of variance (ANOVA) were performed, respectively, to analyze statistically the correlations with the histopathological results and differences among groups. The iron enhancement values were positively correlated with the iron pathology grading (r = 0.729, pVNC) values were negatively correlated with the fat pathology grading (r = -0.642,pVNC values (F = 25.308,pVNC values were only observed between the fat-present and fat-absent groups. Separation of hepatic iron and fat by dual energy material decomposition in vivo was feasible, even when they coexisted.

  9. FOREWORD: Computational methodologies for designing materials Computational methodologies for designing materials

    Science.gov (United States)

    Rahman, Talat S.

    2009-02-01

    study dislocation mobility in a covalent material, which can be a very challenging task for a complex material. Trushin et al [11] present a related procedure for understanding atomistic mechanisms and energetics of strain relaxation in heteroepitaxial systems and transitions from the coherent epitaxial (defect free) state to the state containing an isolated defect (localized or extended). To facilitate the simulation of rare events, Fichthorn et al [12] elaborate on the adoption of the bond-boost method for accelerated molecular dynamics (MD) simulation and its application to kinetic phenomena relevant to thin-film growth. They also present the state-bridging bond-boost method to address the dynamics of systems residing in a group of states connected by small energy barriers and separated from the rest of phase space by large barriers. In the genre of accelerated schemes which also seek to address the issue of completeness in the determination of reaction rates we include here the 'off-lattice' self-learning kinetic Monto Carlo method presented by Kara and co-workers [13] and its application to atomic cluster diffusion on fcc(111) surfaces. Further ramifications of the self-learning kinetic Monte Carlo method are presented in the paper by Nandipati et al [14] , who apply the recently developed optimistic synchronous relaxation (OSR) algorithm as well as the semi-rigorous synchronous sublattice (SL) algorithm for parallel computation of the coarsening of islands on fcc(111) surfaces. The above and related methods also lend themselves to the examination of morphological evolution of functional materials. The contribution by Hamouda et al [15] summarizes the effect of impurities on epitaxial growth and on shape evolution of systems. Similarly, using an atomistic lattice-gas model Li et al [16] describes the key features of the complex mounded morphologies which develop during deposition of Ag films on Ag(111) surfaces. Also, using a combination of a Monte Carlo method and

  10. Separation of hepatic iron and fat by dual-source dual-energy computed tomography based on material decomposition: an animal study.

    Directory of Open Access Journals (Sweden)

    Jing Ma

    Full Text Available OBJECTIVE: To explore the feasibility of dual-source dual-energy computed tomography (DSDECT for hepatic iron and fat separation in vivo. MATERIALS AND METHODS: All of the procedures in this study were approved by the Research Animal Resource Center of Shanghai Ruijin Hospital. Sixty rats that underwent DECT scanning were divided into the normal group, fatty liver group, liver iron group, and coexisting liver iron and fat group, according to Prussian blue and HE staining. The data for each group were reconstructed and post-processed by an iron-specific, three-material decomposition algorithm. The iron enhancement value and the virtual non-iron contrast value, which indicated overloaded liver iron and residual liver tissue, respectively, were measured. Spearman's correlation and one-way analysis of variance (ANOVA were performed, respectively, to analyze statistically the correlations with the histopathological results and differences among groups. RESULTS: The iron enhancement values were positively correlated with the iron pathology grading (r = 0.729, p<0.001. Virtual non-iron contrast (VNC values were negatively correlated with the fat pathology grading (r = -0.642,p<0.0001. Different groups showed significantly different iron enhancement values and VNC values (F = 25.308,p<0.001; F = 10.911, p<0.001, respectively. Among the groups, significant differences in iron enhancement values were only observed between the iron-present and iron-absent groups, and differences in VNC values were only observed between the fat-present and fat-absent groups. CONCLUSION: Separation of hepatic iron and fat by dual energy material decomposition in vivo was feasible, even when they coexisted.

  11. Computational simulation of coupled material degradation processes for probabilistic lifetime strength of aerospace materials

    Science.gov (United States)

    Boyce, Lola; Bast, Callie C.

    1992-01-01

    The research included ongoing development of methodology that provides probabilistic lifetime strength of aerospace materials via computational simulation. A probabilistic material strength degradation model, in the form of a randomized multifactor interaction equation, is postulated for strength degradation of structural components of aerospace propulsion systems subjected to a number of effects or primative variables. These primative variable may include high temperature, fatigue or creep. In most cases, strength is reduced as a result of the action of a variable. This multifactor interaction strength degradation equation has been randomized and is included in the computer program, PROMISS. Also included in the research is the development of methodology to calibrate the above described constitutive equation using actual experimental materials data together with linear regression of that data, thereby predicting values for the empirical material constraints for each effect or primative variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from the open literature for materials typically of interest to those studying aerospace propulsion system components. Material data for Inconel 718 was analyzed using the developed methodology.

  12. Department of Materials Research by Computers - Overview

    International Nuclear Information System (INIS)

    Parlinski, K.

    2000-01-01

    Full text: During 1999 the main activity of the Department has been gradually moved to ab initio calculations. For that we have used the approach of density functional theory with either local density approximation (LDA) or generalized gradient approximation (GGA). This approach allows to find the structure and dynamics of any system which can be represented by a supercell with periodic boundary conditions. Our interests were limited to study of structure and dynamics of crystals. We have used two different packages of software: CASTEP and VASP and the pseudopotentials delivered with these programs. This method is parameter-free, which means that one needs to know only the physical constants, like Planck constant, element masses and electron charge, in order to get a quantitative result. We have concentrated our efforts around four subjects: calculation of phonon dispersion curves for polar crystals with LO/TO splitting, calculations of lattice dynamics of chalcopyrites, calculations of energy barriers in molecular crystals, and calculations of elastic properties and phase transitions in geologically important materials. We have calculated the phonon dispersion curves in ionic cubic MgO crystal. The phonon modes at Γ point are split to LO and TO modes. We have proposed a method to calculate this splitting by an elongated supercell. The results agree very well with the coherent inelastic neutron scattering data. Similar effects have been considered in hexagonal GaN, rhombohedral LiNbO 3 , and tetragonal Sn0 2 . In the two last crystals soft modes, responsible for the phase transitions, were found. Intensive calculations were carried out for tetragonal chalcopyrites structure. Each unit cell contains 16 atoms. By using enlarged supercell of 2 x 2 x 1 size with 64 atoms we could obtain valid phonon dispersion curves for CuInSe 2 , AgGaSe 2 , AgGaTe 2 , which agree with neutron data and Raman scattering results. Studies of the molecular motion in KSCN crystal were

  13. Nuclear material shipment study

    International Nuclear Information System (INIS)

    Shepherd, E.W.

    1980-01-01

    The Radioactive Material Transport Assessment Study is expected to provide a flexible set of capabilities and useful information to the public, industry and government users by using a system design to assure obtaining high quality data from selected industry sources at acceptable cost. It is expected that the shipping record approach coupled with an efficient sampling strategy will accomplish this. The study is also designed to yield analytical capabilities and statistical output to serve public, industry and government users. The information provided by the study will make a valuable contribution to environmental and accident risk assessment, policy development and operational planning and management activities

  14. Enhancing Language Material Availability Using Computers.

    Science.gov (United States)

    Miyashita, Mizuki; Moll, Laura A.

    This paper describes the use of computer technology to produce an updated online Tohono O'odham dictionary. Spoken in southern Arizona and northern Mexico, Tohono O'odham (formerly Papago) and its close relative Akimel O'odham (Pima) had a total of about 25,000 speakers in 1988. Although the language is taught to school children through community…

  15. Editorial: Modelling and computational challenges in granular materials

    OpenAIRE

    Weinhart, Thomas; Thornton, Anthony Richard; Einav, Itai

    2015-01-01

    This is the editorial for the special issue on “Modelling and computational challenges in granular materials” in the journal on Computational Particle Mechanics (CPM). The issue aims to provide an opportunity for physicists, engineers, applied mathematicians and computational scientists to discuss the current progress and latest advancements in the field of advanced numerical methods and modelling of granular materials. The focus will be on computational methods, improved algorithms and the m...

  16. A high performance scientific cloud computing environment for materials simulations

    OpenAIRE

    Jorissen, Kevin; Vila, Fernando D.; Rehr, John J.

    2011-01-01

    We describe the development of a scientific cloud computing (SCC) platform that offers high performance computation capability. The platform consists of a scientific virtual machine prototype containing a UNIX operating system and several materials science codes, together with essential interface tools (an SCC toolset) that offers functionality comparable to local compute clusters. In particular, our SCC toolset provides automatic creation of virtual clusters for parallel computing, including...

  17. A high performance scientific cloud computing environment for materials simulations

    Science.gov (United States)

    Jorissen, K.; Vila, F. D.; Rehr, J. J.

    2012-09-01

    We describe the development of a scientific cloud computing (SCC) platform that offers high performance computation capability. The platform consists of a scientific virtual machine prototype containing a UNIX operating system and several materials science codes, together with essential interface tools (an SCC toolset) that offers functionality comparable to local compute clusters. In particular, our SCC toolset provides automatic creation of virtual clusters for parallel computing, including tools for execution and monitoring performance, as well as efficient I/O utilities that enable seamless connections to and from the cloud. Our SCC platform is optimized for the Amazon Elastic Compute Cloud (EC2). We present benchmarks for prototypical scientific applications and demonstrate performance comparable to local compute clusters. To facilitate code execution and provide user-friendly access, we have also integrated cloud computing capability in a JAVA-based GUI. Our SCC platform may be an alternative to traditional HPC resources for materials science or quantum chemistry applications.

  18. Computational Chemistry Toolkit for Energetic Materials Design

    Science.gov (United States)

    2006-11-01

    industry are aggressively engaged in efforts to develop multiscale modeling and simulation methodologies to model and analyze complex phenomena across...energetic materials design. It is hoped that this toolkit will evolve into a collection of well-integrated multiscale modeling methodologies...Experimenta Theoreticala This Work 1-5-Diamino-4- methyl- tetrazolium nitrate 8.4 41.7 47.5 1-5-Diamino-4- methyl- tetrazolium azide 138.1 161.6

  19. The establishment of computer system for nuclear material accounting

    International Nuclear Information System (INIS)

    Hong, Jong Sook; Lee, Byung Doo; Park, Ho Joon

    1988-01-01

    Computer based nuclear material accountancy system will not only increase the credibility of KOREA-IAEA safeguards agreement and bilateral agreements but also decrease the man-power needed to carry out the inspection activity at state level and at facility level. Computer software for nuclear material accounting for and control has been materialized the application to both item and bulk facilities and software for database at state level has been also established to maintain up -to-date status of nation-wide nuclear material inventory. Computer recordings and reporting have been realized to fulfill the national and international commitments to nuclear material accounting for and control. The exchange of information related to nuclear material accounting for has become possible by PC diskettes. (Author)

  20. Neuromorphic Computing – From Materials Research to Systems Architecture Roundtable

    Energy Technology Data Exchange (ETDEWEB)

    Schuller, Ivan K. [Univ. of California, San Diego, CA (United States); Stevens, Rick [Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Chicago, IL (United States); Pino, Robinson [Dept. of Energy (DOE) Office of Science, Washington, DC (United States); Pechan, Michael [Dept. of Energy (DOE) Office of Science, Washington, DC (United States)

    2015-10-29

    Computation in its many forms is the engine that fuels our modern civilization. Modern computation—based on the von Neumann architecture—has allowed, until now, the development of continuous improvements, as predicted by Moore’s law. However, computation using current architectures and materials will inevitably—within the next 10 years—reach a limit because of fundamental scientific reasons. DOE convened a roundtable of experts in neuromorphic computing systems, materials science, and computer science in Washington on October 29-30, 2015 to address the following basic questions: Can brain-like (“neuromorphic”) computing devices based on new material concepts and systems be developed to dramatically outperform conventional CMOS based technology? If so, what are the basic research challenges for materials sicence and computing? The overarching answer that emerged was: The development of novel functional materials and devices incorporated into unique architectures will allow a revolutionary technological leap toward the implementation of a fully “neuromorphic” computer. To address this challenge, the following issues were considered: The main differences between neuromorphic and conventional computing as related to: signaling models, timing/clock, non-volatile memory, architecture, fault tolerance, integrated memory and compute, noise tolerance, analog vs. digital, and in situ learning New neuromorphic architectures needed to: produce lower energy consumption, potential novel nanostructured materials, and enhanced computation Device and materials properties needed to implement functions such as: hysteresis, stability, and fault tolerance Comparisons of different implementations: spin torque, memristors, resistive switching, phase change, and optical schemes for enhanced breakthroughs in performance, cost, fault tolerance, and/or manufacturability.

  1. Computational simulation of heat transfer in laser melted material flow

    International Nuclear Information System (INIS)

    Shankar, V.; Gnanamuthu, D.

    1986-01-01

    A computational procedure has been developed to study the heat transfer process in laser-melted material flow associated with surface heat treatment of metallic alloys to improve wear-and-tear and corrosion resistance. The time-dependent incompressible Navier-Stokes equations are solved, accounting for both convective and conductive heat transfer processes. The convection, induced by surface tension and high surface temperature gradients, sets up a counterrotating vortex flow within the molten pool. This recirculating material flow is responsible for determining the molten pool shape and the associated cooling rates which affect the solidifying material composition. The numerical method involves an implicit triple-approximate factorization scheme for the energy equation, and an explicit treatment for the momentum and the continuity equations. An experimental setup, using a continuous wave CO 2 laser beam as a heat source, has been carried out to generate data for validation of the computational model. Results in terms of the depth, width, and shape of the molten pool and the heat-affected zone for various power settings and shapes of the laser, and for various travel speeds of the workpiece, compare very well with experimental data. The presence of the surface tension-induced vortex flow is demonstrated

  2. Integrated Computational Material Engineering Technologies for Additive Manufacturing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — QuesTek Innovations, a pioneer in Integrated Computational Materials Engineering (ICME) and a Tibbetts Award recipient, is teaming with University of Pittsburgh,...

  3. COMPUTER MODELING OF STRUCTURAL - CONCENTRATION CHARACTERISTICS OF BUILDING COMPOSITE MATERIALS

    Directory of Open Access Journals (Sweden)

    I. I. Zaripova

    2015-09-01

    Full Text Available In the article the computer modeling of structural and concentration characteristics of the building composite material on the basis of the theory of the package. The main provisions of the algorithmon the basis of which it was possible to get the package with a significant number of packaged elements, making it more representative in comparison with existing analogues modeling. We describe the modeled area related areas, the presence of which determines the possibility of a percolation process, which in turn makes it possible to study and management of individual properties of the composite material of construction. As an example of the construction of a composite material is considered concrete that does not exclude the possibility of using algorithms and modeling results of similar studies for composite matrix type (matrix of the same material and distributed in a certain way by volume particles of another substance. Based on modeling results can be manufactured parts and construction elementsfor various purposes with improved technical characteristics (by controlling the concentration composition substance.

  4. Computer-aided analysis of cutting processes for brittle materials

    Science.gov (United States)

    Ogorodnikov, A. I.; Tikhonov, I. N.

    2017-12-01

    This paper is focused on 3D computer simulation of cutting processes for brittle materials and silicon wafers. Computer-aided analysis of wafer scribing and dicing is carried out with the use of the ANSYS CAE (computer-aided engineering) software, and a parametric model of the processes is created by means of the internal ANSYS APDL programming language. Different types of tool tip geometry are analyzed to obtain internal stresses, such as a four-sided pyramid with an included angle of 120° and a tool inclination angle to the normal axis of 15°. The quality of the workpieces after cutting is studied by optical microscopy to verify the FE (finite-element) model. The disruption of the material structure during scribing occurs near the scratch and propagates into the wafer or over its surface at a short range. The deformation area along the scratch looks like a ragged band, but the stress width is rather low. The theory of cutting brittle semiconductor and optical materials is developed on the basis of the advanced theory of metal turning. The fall of stress intensity along the normal on the way from the tip point to the scribe line can be predicted using the developed theory and with the verified FE model. The crystal quality and dimensions of defects are determined by the mechanics of scratching, which depends on the shape of the diamond tip, the scratching direction, the velocity of the cutting tool and applied force loads. The disunity is a rate-sensitive process, and it depends on the cutting thickness. The application of numerical techniques, such as FE analysis, to cutting problems enhances understanding and promotes the further development of existing machining technologies.

  5. Extreme Scale Computing Studies

    Science.gov (United States)

    2010-12-01

    systems that would fall under the Exascale rubric . In this chapter, we first discuss the attributes by which achievement of the label “Exascale” may be...Carrington, and E. Strohmaier. A Genetic Algorithms Approach to Modeling the Performance of Memory-bound Computations. Reno, NV, November 2007. ACM/IEEE... genetic stochasticity (random mating, mutation, etc). Outcomes are thus stochastic as well, and ecologists wish to ask questions like, “What is the

  6. Computer simulation of multi-elemental fusion reactor materials

    International Nuclear Information System (INIS)

    Voertler, K.

    2011-01-01

    Thermonuclear fusion is a sustainable energy solution, in which energy is produced using similar processes as in the sun. In this technology hydrogen isotopes are fused to gain energy and consequently to produce electricity. In a fusion reactor hydrogen isotopes are confined by magnetic fields as ionized gas, the plasma. Since the core plasma is millions of degrees hot, there are special needs for the plasma-facing materials. Moreover, in the plasma the fusion of hydrogen isotopes leads to the production of high energetic neutrons which sets demanding abilities for the structural materials of the reactor. This thesis investigates the irradiation response of materials to be used in future fusion reactors. Interactions of the plasma with the reactor wall leads to the removal of surface atoms, migration of them, and formation of co-deposited layers such as tungsten carbide. Sputtering of tungsten carbide and deuterium trapping in tungsten carbide was investigated in this thesis. As the second topic the primary interaction of the neutrons in the structural material steel was examined. As model materials for steel iron chromium and iron nickel were used. This study was performed theoretically by the means of computer simulations on the atomic level. In contrast to previous studies in the field, in which simulations were limited to pure elements, in this work more complex materials were used, i.e. they were multi-elemental including two or more atom species. The results of this thesis are in the microscale. One of the results is a catalogue of atom species, which were removed from tungsten carbide by the plasma. Another result is e.g. the atomic distributions of defects in iron chromium caused by the energetic neutrons. These microscopic results are used in data bases for multiscale modelling of fusion reactor materials, which has the aim to explain the macroscopic degradation in the materials. This thesis is therefore a relevant contribution to investigate the

  7. Materials and nanosystems : interdisciplinary computational modeling at multiple scales

    International Nuclear Information System (INIS)

    Huber, S.E.

    2014-01-01

    Over the last five decades, computer simulation and numerical modeling have become valuable tools complementing the traditional pillars of science, experiment and theory. In this thesis, several applications of computer-based simulation and modeling shall be explored in order to address problems and open issues in chemical and molecular physics. Attention shall be paid especially to the different degrees of interrelatedness and multiscale-flavor, which may - at least to some extent - be regarded as inherent properties of computational chemistry. In order to do so, a variety of computational methods are used to study features of molecular systems which are of relevance in various branches of science and which correspond to different spatial and/or temporal scales. Proceeding from small to large measures, first, an application in astrochemistry, the investigation of spectroscopic and energetic aspects of carbonic acid isomers shall be discussed. In this respect, very accurate and hence at the same time computationally very demanding electronic structure methods like the coupled-cluster approach are employed. These studies are followed by the discussion of an application in the scope of plasma-wall interaction which is related to nuclear fusion research. There, the interactions of atoms and molecules with graphite surfaces are explored using density functional theory methods. The latter are computationally cheaper than coupled-cluster methods and thus allow the treatment of larger molecular systems, but yield less accuracy and especially reduced error control at the same time. The subsequently presented exploration of surface defects at low-index polar zinc oxide surfaces, which are of interest in materials science and surface science, is another surface science application. The necessity to treat even larger systems of several hundreds of atoms requires the use of approximate density functional theory methods. Thin gold nanowires consisting of several thousands of

  8. Computer modelling of granular material microfracturing

    CSIR Research Space (South Africa)

    Malan, DF

    1995-08-15

    Full Text Available Interaction and Growth Simulation). Grains were represented by straight-sided polygons generated with a Voronoi generator. Experiments were carried out to simulate experimental micro fracture studies of quartzite in triaxial extension tests. The results...

  9. Computational materials science: The emergence of predictive ...

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    some significant recent developments related to alloy and steel design as well as the study of ... of aggregates of atoms (Kumar et al 2002a), etc. and even problems such as the development ... Cu–Au type fcc or CsCl-type bcc struc- tures.

  10. Computational methods for coupling microstructural and micromechanical materials response simulations

    Energy Technology Data Exchange (ETDEWEB)

    HOLM,ELIZABETH A.; BATTAILE,CORBETT C.; BUCHHEIT,THOMAS E.; FANG,HUEI ELIOT; RINTOUL,MARK DANIEL; VEDULA,VENKATA R.; GLASS,S. JILL; KNOROVSKY,GERALD A.; NEILSEN,MICHAEL K.; WELLMAN,GERALD W.; SULSKY,DEBORAH; SHEN,YU-LIN; SCHREYER,H. BUCK

    2000-04-01

    Computational materials simulations have traditionally focused on individual phenomena: grain growth, crack propagation, plastic flow, etc. However, real materials behavior results from a complex interplay between phenomena. In this project, the authors explored methods for coupling mesoscale simulations of microstructural evolution and micromechanical response. In one case, massively parallel (MP) simulations for grain evolution and microcracking in alumina stronglink materials were dynamically coupled. In the other, codes for domain coarsening and plastic deformation in CuSi braze alloys were iteratively linked. this program provided the first comparison of two promising ways to integrate mesoscale computer codes. Coupled microstructural/micromechanical codes were applied to experimentally observed microstructures for the first time. In addition to the coupled codes, this project developed a suite of new computational capabilities (PARGRAIN, GLAD, OOF, MPM, polycrystal plasticity, front tracking). The problem of plasticity length scale in continuum calculations was recognized and a solution strategy was developed. The simulations were experimentally validated on stockpile materials.

  11. Improved materials management through client/server computing

    International Nuclear Information System (INIS)

    Brooks, D.; Neilsen, E.; Reagan, R.; Simmons, D.

    1992-01-01

    This paper reports that materials management and procurement impacts every organization within an electric utility from power generation to customer service. An efficient material management and procurement system can help improve productivity and minimize operating costs. It is no longer sufficient to simply automate materials management using inventory control systems. Smart companies are building centralized data warehouses and use the client/server style of computing to provide real time data access. This paper describes how Alabama Power Company, Southern Company Services and Digital Equipment Corporation transformed two existing applications, a purchase order application within DEC's ALL-IN-1 environment and a materials management application within an IBM CICS environment, into a data warehouse - client/server application. An application server is used to overcome incompatibilities between computing environments and provide easy, real-time access to information residing in multi-vendor environments

  12. Soft computing in design and manufacturing of advanced materials

    Science.gov (United States)

    Cios, Krzysztof J.; Baaklini, George Y; Vary, Alex

    1993-01-01

    The potential of fuzzy sets and neural networks, often referred to as soft computing, for aiding in all aspects of manufacturing of advanced materials like ceramics is addressed. In design and manufacturing of advanced materials, it is desirable to find which of the many processing variables contribute most to the desired properties of the material. There is also interest in real time quality control of parameters that govern material properties during processing stages. The concepts of fuzzy sets and neural networks are briefly introduced and it is shown how they can be used in the design and manufacturing processes. These two computational methods are alternatives to other methods such as the Taguchi method. The two methods are demonstrated by using data collected at NASA Lewis Research Center. Future research directions are also discussed.

  13. Study of nuclear material accounting

    International Nuclear Information System (INIS)

    Ruderman, H.

    1977-01-01

    The implications of deliberate diversion of nuclear materials on materials accounting, the validity of the MUF concept to establish assurance concerning the possible diversion of special nuclear materials, and an economic analysis to permit cost comparison of varying the inventory frequency are being studied. An inventory cost model, the statistical hypothesis testing approach, the game theoretic approach, and analysis of generic plants are considered

  14. A computational study of the effects of linear doping profile on the high-frequency and switching performances of hetero-material-gate CNTFETs

    International Nuclear Information System (INIS)

    Wang Wei; Li Na; Ren Yuzhou; Li Hao; Zheng Lifen; Li Jin; Jiang Junjie; Chen Xiaoping; Wang Kai; Xia Chunping

    2013-01-01

    The effects of linear doping profile near the source and drain contacts on the switching and high-frequency characteristics for conventional single-material-gate CNTFET (C-CNTFET) and hetero-material-gate CNTFET (HMG-CNTFET) have been theoretically investigated by using a quantum kinetic model. This model is based on two-dimensional non-equilibrium Green's functions (NEGF) solved self-consistently with Poisson's equations. The simulation results show that at a CNT channel length of 20 nm with chirality (7, 0), the intrinsic cutoff frequency of C-CNTFETs reaches up to a few THz. In addition, a comparison study has been performed between C-and HMG-CNTFETs. For the C-CNTFET, results reveal that a longer linear doping length can improve the cutoff frequency and switching speed. However, it has the reverse effect on on/off current ratios. To improve the on/off current ratios performance of CNTFETs and overcome short-channel effects (SCEs) in high-performance device applications, a novel CNTFET structure with a combination of an HMG and linear doping profile has been proposed. It is demonstrated that the HMG structure design with an optimized linear doping length has improved high-frequency and switching performances as compared to C-CNTFETs. The simulation study may be useful for understanding and optimizing high-performance of CNTFETs and assessing the reliability of CNTFETs for prospective applications. (semiconductor devices)

  15. Computer design of porous active materials at different dimensional scales

    Science.gov (United States)

    Nasedkin, Andrey

    2017-12-01

    The paper presents a mathematical and computer modeling of effective properties of porous piezoelectric materials of three types: with ordinary porosity, with metallized pore surfaces, and with nanoscale porosity structure. The described integrated approach includes the effective moduli method of composite mechanics, simulation of representative volumes, and finite element method.

  16. Computed temperature profile in materials exposed to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Ping, Tso Chin; Choong, Yap Siew; Seon, Chan Kam

    1987-06-01

    Computed temperature profiles are presented for the materials of lead, steel, concrete and water in curved shells, when they are exposed to gamma radiation. The results are based on the usual simplified theory of thermal conduction with an exponential heat source.

  17. Transient computational homogenization for heterogeneous materials under dynamic excitation

    NARCIS (Netherlands)

    Pham, N.K.H.; Kouznetsova, V.; Geers, M.G.D.

    2013-01-01

    This paper presents a novel transient computational homogenization procedure that is suitable for the modelling of the evolution in space and in time of materials with non-steady state microstructure, such as metamaterials. This transient scheme is an extension of the classical (first-order)

  18. Continuous Materiality: Through a Hierarchy of Computational Codes

    Directory of Open Access Journals (Sweden)

    Jichen Zhu

    2008-01-01

    Full Text Available The legacy of Cartesian dualism inherent in linguistic theory deeply influences current views on the relation between natural language, computer code, and the physical world. However, the oversimplified distinction between mind and body falls short of capturing the complex interaction between the material and the immaterial. In this paper, we posit a hierarchy of codes to delineate a wide spectrum of continuous materiality. Our research suggests that diagrams in architecture provide a valuable analog for approaching computer code in emergent digital systems. After commenting on ways that Cartesian dualism continues to haunt discussions of code, we turn our attention to diagrams and design morphology. Finally we notice the implications a material understanding of code bears for further research on the relation between human cognition and digital code. Our discussion concludes by noticing several areas that we have projected for ongoing research.

  19. Computational Modelling of Materials for Wind Turbine Blades: Selected DTU Wind Energy Activities.

    Science.gov (United States)

    Mikkelsen, Lars Pilgaard; Mishnaevsky, Leon

    2017-11-08

    Computational and analytical studies of degradation of wind turbine blade materials at the macro-, micro-, and nanoscale carried out by the modelling team of the Section Composites and Materials Mechanics, Department of Wind Energy, DTU, are reviewed. Examples of the analysis of the microstructural effects on the strength and fatigue life of composites are shown. Computational studies of degradation mechanisms of wind blade composites under tensile and compressive loading are presented. The effect of hybrid and nanoengineered structures on the performance of the composite was studied in computational experiments as well.

  20. Computational Discovery of Materials Using the Firefly Algorithm

    Science.gov (United States)

    Avendaño-Franco, Guillermo; Romero, Aldo

    Our current ability to model physical phenomena accurately, the increase computational power and better algorithms are the driving forces behind the computational discovery and design of novel materials, allowing for virtual characterization before their realization in the laboratory. We present the implementation of a novel firefly algorithm, a population-based algorithm for global optimization for searching the structure/composition space. This novel computation-intensive approach naturally take advantage of concurrency, targeted exploration and still keeping enough diversity. We apply the new method in both periodic and non-periodic structures and we present the implementation challenges and solutions to improve efficiency. The implementation makes use of computational materials databases and network analysis to optimize the search and get insights about the geometric structure of local minima on the energy landscape. The method has been implemented in our software PyChemia, an open-source package for materials discovery. We acknowledge the support of DMREF-NSF 1434897 and the Donors of the American Chemical Society Petroleum Research Fund for partial support of this research under Contract 54075-ND10.

  1. Nuclear materials management storage study

    International Nuclear Information System (INIS)

    Becker, G.W. Jr.

    1994-02-01

    The Office of Weapons and Materials Planning (DP-27) requested the Planning Support Group (PSG) at the Savannah River Site to help coordinate a Departmental complex-wide nuclear materials storage study. This study will support the development of management strategies and plans until Defense Programs' Complex 21 is operational by DOE organizations that have direct interest/concerns about or responsibilities for nuclear material storage. They include the Materials Planning Division (DP-273) of DP-27, the Office of the Deputy Assistant Secretary for Facilities (DP-60), the Office of Weapons Complex Reconfiguration (DP-40), and other program areas, including Environmental Restoration and Waste Management (EM). To facilitate data collection, a questionnaire was developed and issued to nuclear materials custodian sites soliciting information on nuclear materials characteristics, storage plans, issues, etc. Sites were asked to functionally group materials identified in DOE Order 5660.1A (Management of Nuclear Materials) based on common physical and chemical characteristics and common material management strategies and to relate these groupings to Nuclear Materials Management Safeguards and Security (NMMSS) records. A database was constructed using 843 storage records from 70 responding sites. The database and an initial report summarizing storage issues were issued to participating Field Offices and DP-27 for comment. This report presents the background for the Storage Study and an initial, unclassified summary of storage issues and concerns identified by the sites

  2. [INVITED] Computational intelligence for smart laser materials processing

    Science.gov (United States)

    Casalino, Giuseppe

    2018-03-01

    Computational intelligence (CI) involves using a computer algorithm to capture hidden knowledge from data and to use them for training ;intelligent machine; to make complex decisions without human intervention. As simulation is becoming more prevalent from design and planning to manufacturing and operations, laser material processing can also benefit from computer generating knowledge through soft computing. This work is a review of the state-of-the-art on the methodology and applications of CI in laser materials processing (LMP), which is nowadays receiving increasing interest from world class manufacturers and 4.0 industry. The focus is on the methods that have been proven effective and robust in solving several problems in welding, cutting, drilling, surface treating and additive manufacturing using the laser beam. After a basic description of the most common computational intelligences employed in manufacturing, four sections, namely, laser joining, machining, surface, and additive covered the most recent applications in the already extensive literature regarding the CI in LMP. Eventually, emerging trends and future challenges were identified and discussed.

  3. Computational and Experimental Insight Into Single-Molecule Piezoelectric Materials

    Science.gov (United States)

    Marvin, Christopher Wayne

    Piezoelectric materials allow for the harvesting of ambient waste energy from the environment. Producing lightweight, highly responsive materials is a challenge for this type of material, requiring polymer, foam, or bio-inspired materials. In this dissertation, I explore the origin of the piezoelectric effect in single molecules through density functional theory (DFT), analyze the piezoresponse of bio-inspired peptidic materials through the use of atomic and piezoresponse force microscopy (AFM and PFM), and develop a novel class of materials combining flexible polyurethane foams and non-piezoelectric, polar dopants. For the DFT calculations, functional group, regiochemical, and heteroatom derivatives of [6]helicene were examined for their influence on the piezoelectric response. An aza[6]helicene derivative was found to have a piezoelectric response (108 pm/V) comparable to ceramics such as lead zirconium titanate (200+ pm/V). These computed materials have the possibility to compete with current field-leading piezomaterials such as lead zirconium titanate (PZT), zinc oxide (ZnO), and polyvinylidene difluoride (PVDF) and its derivatives. The use of AFM/PFM allows for the demonstration of the piezoelectric effect of the selfassembled monolayer (SAM) peptidic systems. Through PFM, the influence that the helicity and sequence of the peptide has on the overall response of the molecule can be analyzed. Finally, development of a novel class of piezoelectrics, the foam-based materials, expands the current understanding of the qualities required for a piezoelectric material from ceramic and rigid materials to more flexible, organic materials. Through the exploration of these novel types of piezoelectric materials, new design rules and figures of merit have been developed.

  4. Computational Design of Batteries from Materials to Systems

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Kandler A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Santhanagopalan, Shriram [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yang, Chuanbo [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Graf, Peter A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Usseglio Viretta, Francois L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Li, Qibo [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Finegan, Donal [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pesaran, Ahmad A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yao, Koffi (Pierre) [Argonne National Laboratory; Abraham, Daniel [Argonne National Laboratory; Dees, Dennis [Argonne National Laboratory; Jansen, Andy [Argonne National Laboratory; Mukherjee, Partha [Texas A& M University; Mistry, Aashutosh [Texas A& M University; Verma, Ankit [Texas A& M University; Lamb, Josh [Sandia National Laboratories; Darcy, Eric [NASA

    2017-09-01

    Computer models are helping to accelerate the design and validation of next generation batteries and provide valuable insights not possible through experimental testing alone. Validated 3-D physics-based models exist for predicting electrochemical performance, thermal and mechanical response of cells and packs under normal and abuse scenarios. The talk describes present efforts to make the models better suited for engineering design, including improving their computation speed, developing faster processes for model parameter identification including under aging, and predicting the performance of a proposed electrode material recipe a priori using microstructure models.

  5. Computer system for International Reactor Pressure Vessel Materials Database support

    International Nuclear Information System (INIS)

    Arutyunjan, R.; Kabalevsky, S.; Kiselev, V.; Serov, A.

    1997-01-01

    This report presents description of the computer tools for support of International Reactor Pressure Vessel Materials Database developed at IAEA. Work was focused on raw, qualified, processed materials data, search, retrieval, analysis, presentation and export possibilities of data. Developed software has the following main functions: provides software tools for querying and search of any type of data in the database; provides the capability to update the existing information in the database; provides the capability to present and print selected data; provides the possibility of export on yearly basis the run-time IRPVMDB with raw, qualified and processed materials data to Database members; provides the capability to export any selected sets of raw, qualified, processed materials data

  6. Multiscale modeling of complex materials phenomenological, theoretical and computational aspects

    CERN Document Server

    Trovalusci, Patrizia

    2014-01-01

    The papers in this volume deal with materials science, theoretical mechanics and experimental and computational techniques at multiple scales, providing a sound base and a framework for many applications which are hitherto treated in a phenomenological sense. The basic principles are formulated of multiscale modeling strategies towards modern complex multiphase materials subjected to various types of mechanical, thermal loadings and environmental effects. The focus is on problems where mechanics is highly coupled with other concurrent physical phenomena. Attention is also focused on the historical origins of multiscale modeling and foundations of continuum mechanics currently adopted to model non-classical continua with substructure, for which internal length scales play a crucial role.

  7. Investigations into radiation damages of reactor materials by computer simulation

    International Nuclear Information System (INIS)

    Bronnikov, V.A.

    2004-01-01

    Data on the state of works in European countries in the field of computerized simulation of radiation damages of reactor materials under the context of the international projects ITEM (European Database for Multiscale Modelling) and SIRENA (Simulation of Radiation Effects in Zr-Nb alloys) - computerized simulation of stress corrosion when contact of Zr-Nb alloys with iodine are presented. Computer codes for the simulation of radiation effects in reactor materials were developed. European Database for Multiscale Modelling (EDAM) was organized using the results of the investigations provided in the ITEM project [ru

  8. Comparing ProFile Vortex to ProTaper Next for the efficacy of removal of root filling material: An ex vivo micro-computed tomography study

    Directory of Open Access Journals (Sweden)

    Emad AlShwaimi

    2018-01-01

    Conclusion: Our findings suggest that PV is as effective as PTN for removal of root canal filling material. Therefore, PV can be considered for use in endodontic retreatment, although more effective files or techniques are still required.

  9. RADTRAN: a computer code to analyze transportation of radioactive material

    International Nuclear Information System (INIS)

    Taylor, J.M.; Daniel, S.L.

    1977-04-01

    A computer code is presented which predicts the environmental impact of any specific scheme of radioactive material transportation. Results are presented in terms of annual latent cancer fatalities and annual early fatility probability resulting from exposure, during normal transportation or transport accidents. The code is developed in a generalized format to permit wide application including normal transportation analysis; consideration of alternatives; and detailed consideration of specific sectors of industry

  10. Aberration studies and computer algebra

    International Nuclear Information System (INIS)

    Hawkes, P.W.

    1981-01-01

    The labour of calculating expressions for aberration coefficients is considerably lightened if a computer algebra language is used to perform the various substitutions and expansions involved. After a brief discussion of matrix representations of aberration coefficients, a particular language, which has shown itself to be well adapted to particle optics, is described and applied to the study of high frequency cavity lenses. (orig.)

  11. A New Approach for Studying Bond Rupture/Closure of a Spiro Benzopyran Photochromic Material: Reactivity Descriptors Derived from Frontier Orbitals and DFT Computed Electrostatic Potential Energy Surface Maps

    Directory of Open Access Journals (Sweden)

    M. S. A. Abdel-Mottaleb

    2016-01-01

    Full Text Available This paper focuses on computations technique within the framework of the TD-DFT theory for studying the relationship between structure-properties of reversible conversion of photochromic materials. Specifically, we report on 1′,3′-dihydro-8-methoxy-1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-(2H-indole] (SP and its isomers. TD-DFT calculated UV-Vis electronic spectra of the closed and open isomers of this photochromic material are in excellent agreement with the experimental results. Moreover, this paper reports on the results of theoretical investigations of reactivity indices that may govern the conversion between spiropyrans and its isomers. In addition, the solvent and rigidity of the medium significantly control the thermal bleaching of the photogenerated colored isomers and hence the switch ability pattern of the photochromic material. The effect of molecular structure computed by DFT in gas-phase and solvents on Cspiro-O bond length has been shown to correlate with photochromic properties. For this compound, DFT optimized geometry could be used to predict photochromism. Furthermore, in an attempt to predict the driving force for MC → SP, this work explores, for the first time, profitable exploitation of the calculated and visualized mapped electrostatic potential energy surfaces (ESP map. Interestingly, it seems that the electrostatic potential forces over the molecular fragments govern spirobond rupture/closure reactions. Thermodynamically, all-trans-colored isomer (CTT is the most stable merocyanine-like form.

  12. Materials-by-design: computation, synthesis, and characterization from atoms to structures

    Science.gov (United States)

    Yeo, Jingjie; Jung, Gang Seob; Martín-Martínez, Francisco J.; Ling, Shengjie; Gu, Grace X.; Qin, Zhao; Buehler, Markus J.

    2018-05-01

    In the 50 years that succeeded Richard Feynman’s exposition of the idea that there is ‘plenty of room at the bottom’ for manipulating individual atoms for the synthesis and manufacturing processing of materials, the materials-by-design paradigm is being developed gradually through synergistic integration of experimental material synthesis and characterization with predictive computational modeling and optimization. This paper reviews how this paradigm creates the possibility to develop materials according to specific, rational designs from the molecular to the macroscopic scale. We discuss promising techniques in experimental small-scale material synthesis and large-scale fabrication methods to manipulate atomistic or macroscale structures, which can be designed by computational modeling. These include recombinant protein technology to produce peptides and proteins with tailored sequences encoded by recombinant DNA, self-assembly processes induced by conformational transition of proteins, additive manufacturing for designing complex structures, and qualitative and quantitative characterization of materials at different length scales. We describe important material characterization techniques using numerous methods of spectroscopy and microscopy. We detail numerous multi-scale computational modeling techniques that complements these experimental techniques: DFT at the atomistic scale; fully atomistic and coarse-grain molecular dynamics at the molecular to mesoscale; continuum modeling at the macroscale. Additionally, we present case studies that utilize experimental and computational approaches in an integrated manner to broaden our understanding of the properties of two-dimensional materials and materials based on silk and silk-elastin-like proteins.

  13. Adhesive Bonding to Computer-aided Design/ Computer-aided Manufacturing Esthetic Dental Materials: An Overview.

    Science.gov (United States)

    Awad, Mohamed Moustafa; Alqahtani, H; Al-Mudahi, A; Murayshed, M S; Alrahlah, A; Bhandi, Shilpa H

    2017-07-01

    To review the adhesive bonding to different computer-aided design/computer-aided manufacturing (CAD/CAM) esthetic restorative materials. The use of CAD/CAM esthetic restorative materials has gained popularity in recent years. Several CAD/ CAM esthetic restorative materials are commercially available. Adhesive bonding is a major determinant of success of CAD/ CAM restorations. Review result: An account of the currently available bonding strategies are discussed with their rationale in various CAD/ CAM materials. Different surface treatment methods as well as adhesion promoters can be used to achieve reliable bonding of CAD/CAM restorative materials. Selection of bonding strategy to such material is determined based on its composition. Further evidence is required to evaluate the effect of new surface treatment methods, such as nonthermal atmospheric plasma and self-etching ceramic primer on bonding to different dental ceramics. An understanding of the currently available bonding strategies to CA/CAM materials can help the clinician to select the most indicated system for each category of materials.

  14. Development of integrated platform for computational material design

    Energy Technology Data Exchange (ETDEWEB)

    Kiyoshi, Matsubara; Kumi, Itai; Nobutaka, Nishikawa; Akifumi, Kato [Center for Computational Science and Engineering, Fuji Research Institute Corporation (Japan); Hideaki, Koike [Advance Soft Corporation (Japan)

    2003-07-01

    The goal of our project is to design and develop a problem-solving environment (PSE) that will help computational scientists and engineers develop large complicated application software and simulate complex phenomena by using networking and parallel computing. The integrated platform, which is designed for PSE in the Japanese national project of Frontier Simulation Software for Industrial Science, is defined by supporting the entire range of problem solving activity from program formulation and data setup to numerical simulation, data management, and visualization. A special feature of our integrated platform is based on a new architecture called TASK FLOW. It integrates the computational resources such as hardware and software on the network and supports complex and large-scale simulation. This concept is applied to computational material design and the project 'comprehensive research for modeling, analysis, control, and design of large-scale complex system considering properties of human being'. Moreover this system will provide the best solution for developing large and complicated software and simulating complex and large-scaled phenomena in computational science and engineering. A prototype has already been developed and the validation and verification of an integrated platform will be scheduled by using the prototype in 2003. In the validation and verification, fluid-structure coupling analysis system for designing an industrial machine will be developed on the integrated platform. As other examples of validation and verification, integrated platform for quantum chemistry and bio-mechanical system are planned.

  15. Development of integrated platform for computational material design

    International Nuclear Information System (INIS)

    Kiyoshi, Matsubara; Kumi, Itai; Nobutaka, Nishikawa; Akifumi, Kato; Hideaki, Koike

    2003-01-01

    The goal of our project is to design and develop a problem-solving environment (PSE) that will help computational scientists and engineers develop large complicated application software and simulate complex phenomena by using networking and parallel computing. The integrated platform, which is designed for PSE in the Japanese national project of Frontier Simulation Software for Industrial Science, is defined by supporting the entire range of problem solving activity from program formulation and data setup to numerical simulation, data management, and visualization. A special feature of our integrated platform is based on a new architecture called TASK FLOW. It integrates the computational resources such as hardware and software on the network and supports complex and large-scale simulation. This concept is applied to computational material design and the project 'comprehensive research for modeling, analysis, control, and design of large-scale complex system considering properties of human being'. Moreover this system will provide the best solution for developing large and complicated software and simulating complex and large-scaled phenomena in computational science and engineering. A prototype has already been developed and the validation and verification of an integrated platform will be scheduled by using the prototype in 2003. In the validation and verification, fluid-structure coupling analysis system for designing an industrial machine will be developed on the integrated platform. As other examples of validation and verification, integrated platform for quantum chemistry and bio-mechanical system are planned

  16. Research Update: Computational materials discovery in soft matter

    Directory of Open Access Journals (Sweden)

    Tristan Bereau

    2016-05-01

    Full Text Available Soft matter embodies a wide range of materials, which all share the common characteristics of weak interaction energies determining their supramolecular structure. This complicates structure-property predictions and hampers the direct application of data-driven approaches to their modeling. We present several aspects in which these methods play a role in designing soft-matter materials: drug design as well as information-driven computer simulations, e.g., histogram reweighting. We also discuss recent examples of rational design of soft-matter materials fostered by physical insight and assisted by data-driven approaches. We foresee the combination of data-driven and physical approaches a promising strategy to move the field forward.

  17. Computational modeling, optimization and manufacturing simulation of advanced engineering materials

    CERN Document Server

    2016-01-01

    This volume presents recent research work focused in the development of adequate theoretical and numerical formulations to describe the behavior of advanced engineering materials.  Particular emphasis is devoted to applications in the fields of biological tissues, phase changing and porous materials, polymers and to micro/nano scale modeling. Sensitivity analysis, gradient and non-gradient based optimization procedures are involved in many of the chapters, aiming at the solution of constitutive inverse problems and parameter identification. All these relevant topics are exposed by experienced international and inter institutional research teams resulting in a high level compilation. The book is a valuable research reference for scientists, senior undergraduate and graduate students, as well as for engineers acting in the area of computational material modeling.

  18. Computational micromechanics of wind blade materials: recent activities at the Materials Research Division, Risoe DTU

    Energy Technology Data Exchange (ETDEWEB)

    Mishnaevsky Jr., L.; Broendsted, P.; Qing, H.; Wang, H.; Soerensen, Bent F. (Technical Univ. of Denmark, Riso National Lab. for Sustainable Energy. Materials Research Div., Roskilde (Denmark)); OEstergaard, R.C. (LM Wind Power Blades, Composite Mechanics, Roskilde (Denmark))

    2010-10-22

    Recent research works in the area of 3D computational microstructural modelling, virtual testing and numerical optimization of wind blade materials, carried out at the Materials Research Division, Rise DTU (Programme Composites and Materials Mechanics) are summarized. The works presented here have been carried out in the framework of several research projects: EU FP6 Upwind, Danida project 'Development of wind energy technologies in Nepal' and SinoDanish project '3D Virtual Testing of composites for wind energy applications' as well as the Framework Program 'Interface design of composite materials' and recently established Danish Centre for Composite Structures and Materials for Wind Turbines. Different groups of materials, which are used or have a potential for use for the wind turbine blades, are modelled with the use of the methods of the computational micromechanics, in particular: (1) glass and carbon fiber reinforced polymer composites used in the large wind turbine blades, (2) different sorts of timber, used in small wind turbines (first of all, in developing countries) and (3) nanoparticle reinforced polymer matrix composites (which have a potential to be used as components for future high strength wind blades). On the basis of the developed 3D microstructural finite element models of these materials, we analyzed the effect of their microstructures on damage resistance, strength and stiffness. The methods of the 3D model design and results of the simulations are discussed in this paper. (Author)

  19. Artist Material BRDF Database for Computer Graphics Rendering

    Science.gov (United States)

    Ashbaugh, Justin C.

    The primary goal of this thesis was to create a physical library of artist material samples. This collection provides necessary data for the development of a gonio-imaging system for use in museums to more accurately document their collections. A sample set was produced consisting of 25 panels and containing nearly 600 unique samples. Selected materials are representative of those commonly used by artists both past and present. These take into account the variability in visual appearance resulting from the materials and application techniques used. Five attributes of variability were identified including medium, color, substrate, application technique and overcoat. Combinations of these attributes were selected based on those commonly observed in museum collections and suggested by surveying experts in the field. For each sample material, image data is collected and used to measure an average bi-directional reflectance distribution function (BRDF). The results are available as a public-domain image and optical database of artist materials at art-si.org. Additionally, the database includes specifications for each sample along with other information useful for computer graphics rendering such as the rectified sample images and normal maps.

  20. Computational Modelling of Materials for Wind Turbine Blades: Selected DTUWind Energy Activities

    DEFF Research Database (Denmark)

    Mikkelsen, Lars Pilgaard; Mishnaevsky, Leon

    2017-01-01

    Computational and analytical studies of degradation of wind turbine blade materials at the macro-, micro-, and nanoscale carried out by the modelling team of the Section Composites and Materials Mechanics, Department of Wind Energy, DTU, are reviewed. Examples of the analysis of the microstructural...... effects on the strength and fatigue life of composites are shown. Computational studies of degradation mechanisms of wind blade composites under tensile and compressive loading are presented. The effect of hybrid and nanoengineered structures on the performance of the composite was studied...

  1. The Effects of Computer Assisted Instruction Materials on Approximate Number Skills of Students with Dyscalculia

    Science.gov (United States)

    Mutlu, Yilmaz; Akgün, Levent

    2017-01-01

    The aim of this study is to examine the effects of computer assisted instruction materials on approximate number skills of students with mathematics learning difficulties. The study was carried out with pretest-posttest quasi experimental method with a single subject. The participants of the study consist of a girl and two boys who attend 3rd…

  2. Integrated Computational Materials Engineering for Magnesium in Automotive Body Applications

    Science.gov (United States)

    Allison, John E.; Liu, Baicheng; Boyle, Kevin P.; Hector, Lou; McCune, Robert

    This paper provides an overview and progress report for an international collaborative project which aims to develop an ICME infrastructure for magnesium for use in automotive body applications. Quantitative processing-micro structure-property relationships are being developed for extruded Mg alloys, sheet-formed Mg alloys and high pressure die cast Mg alloys. These relationships are captured in computational models which are then linked with manufacturing process simulation and used to provide constitutive models for component performance analysis. The long term goal is to capture this information in efficient computational models and in a web-centered knowledge base. The work is being conducted at leading universities, national labs and industrial research facilities in the US, China and Canada. This project is sponsored by the U.S. Department of Energy, the U.S. Automotive Materials Partnership (USAMP), Chinese Ministry of Science and Technology (MOST) and Natural Resources Canada (NRCan).

  3. Efficacy of CM-Wire, M-Wire, and Nickel-Titanium Instruments for Removing Filling Material from Curved Root Canals: A Micro-Computed Tomography Study.

    Science.gov (United States)

    Rodrigues, Clarissa Teles; Duarte, Marco Antonio Hungaro; de Almeida, Marcela Milanezi; de Andrade, Flaviana Bombarda; Bernardineli, Norberti

    2016-11-01

    The aim of this ex vivo study was to evaluate the removal of filling material after using CM-wire, M-wire, and nickel-titanium instruments in both reciprocating and rotary motions in curved canals. Thirty maxillary lateral incisors were divided into 9 groups according to retreatment procedures: Reciproc R25 followed by Mtwo 40/.04 and ProDesign Logic 50/.01 files; ProDesign R 25/.06 followed by ProDesign Logic 40/.05 and ProDesign Logic 50/.01 files; and Gates-Glidden drills, Hedström files, and K-files up to apical size 30 followed by K-file 40 and K-file 50 up to the working length. Micro-computed tomography scans were performed before and after each reinstrumentation procedure to evaluate root canal filling removal. Statistical analysis was performed with Kruskal-Wallis, Friedman, and Wilcoxon tests (P < .05). No significant differences in filling material removal were found in the 3 groups of teeth. The use of Mtwo and ProDesign Logic 40/.05 rotary files did not enhance filling material removal after the use of reciprocating files. The use of ProDesign Logic 50/.01 files significantly reduced the amount of filling material at the apical levels compared with the use of reciprocating files. Association of reciprocating and rotary files was capable of removing a large amount of filling material in the retreatment of curved canals, irrespective of the type of alloy of the instruments. The use of a ProDesign Logic 50/.01 file for apical preparation significantly reduced the amount of remnant material in the apical portion when compared with reciprocating instruments. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  4. Computer modeling of nuclide adsorption on geologic materials

    International Nuclear Information System (INIS)

    Silva, R.J.; White, A.R.; Yee, A.W.

    1980-07-01

    A computer program, called MINEQL, has been developed and is being tested for use in predicting the distribution of radionuclides between solid and aqueous species for a variety of geologic materials and solution conditions. MINEQL is designed to accept a list of components of a system (electrolytes, solid substrates and radionuclides) and their total analytical concentrations, solve the appropriate set of mass balance and equilibrium expressions, and produce a list of the identities and concentrations of all species formed by interactions among the components and between them and/or water

  5. Associated computational plasticity schemes for nonassociated frictional materials

    DEFF Research Database (Denmark)

    Krabbenhoft, K.; Karim, M. R.; Lyamin, A. V.

    2012-01-01

    A new methodology for computational plasticity of nonassociated frictional materials is presented. The new approach is inspired by the micromechanical origins of friction and results in a set of governing equations similar to those of standard associated plasticity. As such, procedures previously...... developed for associated plasticity are applicable with minor modification. This is illustrated by adaptation of the standard implicit scheme. Moreover, the governing equations can be cast in terms of a variational principle, which after discretization is solved by means of a newly developed second...

  6. Computational studies of tokamak plasmas

    International Nuclear Information System (INIS)

    Takizuka, Tomonori; Tsunematsu, Toshihide; Tokuda, Shinji

    1981-02-01

    Computational studies of tokamak plasmas are extensively advanced. Many computational codes have been developed by using several kinds of models, i.e., the finite element formulation of MHD equations, the time dependent multidimensional fluid model, and the particle model with the Monte-Carlo method. These codes are applied to the analyses of the equilibrium of an axisymmetric toroidal plasma (SELENE), the time evolution of the high-beta tokamak plasma (APOLLO), the low-n MHD stability (ERATO-J) and high-n ballooning mode stability (BOREAS) in the INTOR tokamak, the nonlinear MHD stability, such as the positional instability (AEOLUS-P), resistive internal mode (AEOLUS-I) etc., and the divertor functions. (author)

  7. Computational Modeling of Ultrafast Pulse Propagation in Nonlinear Optical Materials

    Science.gov (United States)

    Goorjian, Peter M.; Agrawal, Govind P.; Kwak, Dochan (Technical Monitor)

    1996-01-01

    There is an emerging technology of photonic (or optoelectronic) integrated circuits (PICs or OEICs). In PICs, optical and electronic components are grown together on the same chip. rib build such devices and subsystems, one needs to model the entire chip. Accurate computer modeling of electromagnetic wave propagation in semiconductors is necessary for the successful development of PICs. More specifically, these computer codes would enable the modeling of such devices, including their subsystems, such as semiconductor lasers and semiconductor amplifiers in which there is femtosecond pulse propagation. Here, the computer simulations are made by solving the full vector, nonlinear, Maxwell's equations, coupled with the semiconductor Bloch equations, without any approximations. The carrier is retained in the description of the optical pulse, (i.e. the envelope approximation is not made in the Maxwell's equations), and the rotating wave approximation is not made in the Bloch equations. These coupled equations are solved to simulate the propagation of femtosecond optical pulses in semiconductor materials. The simulations describe the dynamics of the optical pulses, as well as the interband and intraband.

  8. Computational simulation of materials notes for lectures given at UCSB, May 1996--June 1996

    Energy Technology Data Exchange (ETDEWEB)

    LeSar, R.

    1997-01-01

    This report presents information from a lecture given on the computational simulation of materials. The purpose is to introduce modern computerized simulation methods for materials properties and response.

  9. Multiscale paradigms in integrated computational materials science and engineering materials theory, modeling, and simulation for predictive design

    CERN Document Server

    Runge, Keith; Muralidharan, Krishna

    2016-01-01

    This book presents cutting-edge concepts, paradigms, and research highlights in the field of computational materials science and engineering, and provides a fresh, up-to-date perspective on solving present and future materials challenges. The chapters are written by not only pioneers in the fields of computational materials chemistry and materials science, but also experts in multi-scale modeling and simulation as applied to materials engineering. Pedagogical introductions to the different topics and continuity between the chapters are provided to ensure the appeal to a broad audience and to address the applicability of integrated computational materials science and engineering for solving real-world problems.

  10. Global Seabed Materials and Habitats Mapped: The Computational Methods

    Science.gov (United States)

    Jenkins, C. J.

    2016-02-01

    What the seabed is made of has proven difficult to map on the scale of whole ocean-basins. Direct sampling and observation can be augmented with proxy-parameter methods such as acoustics. Both avenues are essential to obtain enough detail and coverage, and also to validate the mapping methods. We focus on the direct observations such as samplings, photo and video, probes, diver and sub reports, and surveyed features. These are often in word-descriptive form: over 85% of the records for site materials are in this form, whether as sample/view descriptions or classifications, or described parameters such as consolidation, color, odor, structures and components. Descriptions are absolutely necessary for unusual materials and for processes - in other words, for research. This project dbSEABED not only has the largest collection of seafloor materials data worldwide, but it uses advanced computing math to obtain the best possible coverages and detail. Included in those techniques are linguistic text analysis (e.g., Natural Language Processing, NLP), fuzzy set theory (FST), and machine learning (ML, e.g., Random Forest). These techniques allow efficient and accurate import of huge datasets, thereby optimizing the data that exists. They merge quantitative and qualitative types of data for rich parameter sets, and extrapolate where the data are sparse for best map production. The dbSEABED data resources are now very widely used worldwide in oceanographic research, environmental management, the geosciences, engineering and survey.

  11. Influence of contrast materials on dose calculation in radiotherapy planning using computed tomography for tumors at various anatomical regions: A prospective study

    International Nuclear Information System (INIS)

    Shibamoto, Yuta; Naruse, Asaka; Fukuma, Hiroshi; Ayakawa, Shiho; Sugie, Chikao; Tomita, Natsuo

    2007-01-01

    Influences of iodinated contrast media on dose calculation were studied in 26 patients. Mean increases in monitor units by contrast media administration were less than 1% and considered negligible in planning of whole-brain, whole-neck, mediastinal, and whole-pelvic irradiation. However, mean increases over 2% were seen in planning of upper-abdominal radiotherapy

  12. Luminescence studies of molecular materials

    International Nuclear Information System (INIS)

    Miller, P.F.

    2000-01-01

    Molecular materials have been widely studied for their potential uses in novel semiconductor devices. They occupy the intellectually interesting area between molecular and bulk descriptions of matter, and as such often have unique and useful characteristics. The design and engineering of these structures is inter-disciplinary in its nature, embracing the fields of physics, electrical engineering and both synthetic and physical chemistry. In this thesis luminescence studies of molecular materials will be presented that probe the nature of the excited states in two promising semiconductor systems. Luminescence techniques provide a powerful and sensitive tool in the investigation of kinetic pathways of radiative and non-radiative emission from these samples. This is particularly appropriate here, as the materials being studied are of potential use in electroluminescent devices. The suitability of photoluminescence techniques comes from both the electroluminescence and photoluminescence sharing the same emitting state. The first class of material studied here is an organic semiconducting polymer, cyano-substituted polyphenylenevinylene (CN-PPV). Conjugated polymers combine semiconducting electronic properties with favourable processing properties and offer the possibility of tuning their optical and electronic properties chemically. The cyanosubstitution increases the electron affinity of the polymer backbone, facilitating electron injection in light-emitting diodes. The polymers are soluble in solvents such as toluene and chloroform due the presence of alkoxy sidegroups. CdSe semiconductor nanocrystals are the other class of material characterised in this work. Semiconductor nanocrystals exhibit interesting size-tunable optical properties due to the confinement of the electronic wave functions. Characterisation of samples produced by different synthetic routes has been carried out to demonstrate the advantages of a novel synthetic method in terms of physical and

  13. Analysis of material flow in metal forming processes by using computer simulation and experiment with model material

    International Nuclear Information System (INIS)

    Kim, Heon Young; Kim, Dong Won

    1993-01-01

    The objective of the present study is to analyze material flow in the metal forming processes by using computer simulation and experiment with model material, plasticine. A UBET program is developed to analyze the bulk flow behaviour of various metal forming problems. The elemental strain-hardening effect is considered in an incremental manner and the element system is automatically regenerated at every deforming step in the program. The material flow behaviour in closed-die forging process with rib-web type cavity are analyzed by UBET and elastic-plastic finite element method, and verified by experiments with plasticine. There were good agreements between simulation and experiment. The effect of corner rounding on material flow behavior is investigated in the analysis of backward extrusion with square die. Flat punch indentation process is simulated by UBET, and the results are compared with that of elastic-plastic finite element method. (Author)

  14. Studi Perbandingan Layanan Cloud Computing

    Directory of Open Access Journals (Sweden)

    Afdhal Afdhal

    2014-03-01

    Full Text Available In the past few years, cloud computing has became a dominant topic in the IT area. Cloud computing offers hardware, infrastructure, platform and applications without requiring end-users knowledge of the physical location and the configuration of providers who deliver the services. It has been a good solution to increase reliability, reduce computing cost, and make opportunities to IT industries to get more advantages. The purpose of this article is to present a better understanding of cloud delivery service, correlation and inter-dependency. This article compares and contrasts the different levels of delivery services and the development models, identify issues, and future directions on cloud computing. The end-users comprehension of cloud computing delivery service classification will equip them with knowledge to determine and decide which business model that will be chosen and adopted securely and comfortably. The last part of this article provides several recommendations for cloud computing service providers and end-users.

  15. Studi Perbandingan Layanan Cloud Computing

    OpenAIRE

    Afdhal, Afdhal

    2013-01-01

    In the past few years, cloud computing has became a dominant topic in the IT area. Cloud computing offers hardware, infrastructure, platform and applications without requiring end-users knowledge of the physical location and the configuration of providers who deliver the services. It has been a good solution to increase reliability, reduce computing cost, and make opportunities to IT industries to get more advantages. The purpose of this article is to present a better understanding of cloud d...

  16. A computational study of high entropy alloys

    Science.gov (United States)

    Wang, Yang; Gao, Michael; Widom, Michael; Hawk, Jeff

    2013-03-01

    As a new class of advanced materials, high-entropy alloys (HEAs) exhibit a wide variety of excellent materials properties, including high strength, reasonable ductility with appreciable work-hardening, corrosion and oxidation resistance, wear resistance, and outstanding diffusion-barrier performance, especially at elevated and high temperatures. In this talk, we will explain our computational approach to the study of HEAs that employs the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method. The KKR-CPA method uses Green's function technique within the framework of multiple scattering theory and is uniquely designed for the theoretical investigation of random alloys from the first principles. The application of the KKR-CPA method will be discussed as it pertains to the study of structural and mechanical properties of HEAs. In particular, computational results will be presented for AlxCoCrCuFeNi (x = 0, 0.3, 0.5, 0.8, 1.0, 1.3, 2.0, 2.8, and 3.0), and these results will be compared with experimental information from the literature.

  17. Investigational research on the design of computational materials; Keisanki zairyo sekkei no chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Computer chemistry was investigationally studied. The advance of theoretical chemistry is indispensable to the design of materials, and the theory and high speed computational method are expected which can simulate the real system with more accuracy. It is basic to simulate structures and physical properties of structural molecules and the aggregate, but the meso region, the intermedium region between structural molecules and the aggregate, has became regarded as important. Rough visualization models in high polymer materials and the progress of computational software/hardware of quantum chemistry/molecular dynamics such as catalyst become necessary. Seamless zooming is proposed as a concept of the software which simulates materials from micro/macro/meso viewpoints. Moreover, to make the most of computer chemistry, an integrated system is necessary which generally handles computational software, database, etc. For the development of software, indispensable is the demonstrative verification by a combination of experiments and researchers. Under a commission from NEDO, the investigational research was conducted as a leading study during fiscal 1996 and 1997 to view the course of the research. 17 refs., 37 figs., 5 tabs.

  18. Computational studies on energetic properties of nitrogen-rich ...

    Indian Academy of Sciences (India)

    Computational studies on energetic properties of nitrogen-rich energetic materials with ditetrazoles. LI XIAO-HONGa,b,∗ and ZHANG RUI-ZHOUa. aCollege of Physics and Engineering, Henan University of Science and Technology, Luoyang 471 003, China. bLuoyang Key Laboratory of Photoelectric Functional Materials, ...

  19. A computer program for controlling a university radioactive material inventory: From confusion to computer to control

    International Nuclear Information System (INIS)

    Robb, D.B.; Riches, C.G.; O'Brian, M.J.; Riordan, F.J.

    1984-01-01

    The University of Washington is a large user of radioactive material. Over 250 authorized programs are working in over 600 labs with nearly 3500 orders of radioactive material per year. The state license sets limits on the total amount of material on campus. There are also limits on sewer disposal. To meet these needs it is necessary to know the amount of material on campus at any time. A computer program was developed which covered many aspects of the radiation safety record needs including inventory control. Inventory is now managed by tracking each order from purchase to disposal. A screen menu as part of the interactive program allows immediate and detailed information about the inventory at time of purchase approval and delivery. Because of this system our knowledge and control of radionuclide work on campus has increased dramatically. A description of how this system is used during ordering, delivery and disposal will be given. Details on the methods to check limits are included along with a summary of the reports made possible by the current data files

  20. Computational design of surfaces, nanostructures and optoelectronic materials

    Science.gov (United States)

    Choudhary, Kamal

    Properties of engineering materials are generally influenced by defects such as point defects (vacancies, interstitials, substitutional defects), line defects (dislocations), planar defects (grain boundaries, free surfaces/nanostructures, interfaces, stacking faults) and volume defects (voids). Classical physics based molecular dynamics and quantum physics based density functional theory can be useful in designing materials with controlled defect properties. In this thesis, empirical potential based molecular dynamics was used to study the surface modification of polymers due to energetic polyatomic ion, thermodynamics and mechanics of metal-ceramic interfaces and nanostructures, while density functional theory was used to screen substituents in optoelectronic materials. Firstly, polyatomic ion-beams were deposited on polymer surfaces and the resulting chemical modifications of the surface were examined. In particular, S, SC and SH were deposited on amorphous polystyrene (PS), and C2H, CH3, and C3H5 were deposited on amorphous poly (methyl methacrylate) (PMMA) using molecular dynamics simulations with classical reactive empirical many-body (REBO) potentials. The objective of this work was to elucidate the mechanisms by which the polymer surface modification took place. The results of the work could be used in tailoring the incident energy and/or constituents of ion beam for obtaining a particular chemistry inside the polymer surface. Secondly, a new Al-O-N empirical potential was developed within the charge optimized many body (COMB) formalism. This potential was then used to examine the thermodynamic stability of interfaces and mechanical properties of nanostructures composed of aluminum, its oxide and its nitride. The potentials were tested for these materials based on surface energies, defect energies, bulk phase stability, the mechanical properties of the most stable bulk phase, its phonon properties as well as with a genetic algorithm based evolution theory of

  1. Computational screening of organic materials towards improved photovoltaic properties

    Science.gov (United States)

    Dai, Shuo; Olivares-Amaya, Roberto; Amador-Bedolla, Carlos; Aspuru-Guzik, Alan; Borunda, Mario

    2015-03-01

    The world today faces an energy crisis that is an obstruction to the development of the human civilization. One of the most promising solutions is solar energy harvested by economical solar cells. Being the third generation of solar cell materials, organic photovoltaic (OPV) materials is now under active development from both theoretical and experimental points of view. In this study, we constructed a parameter to select the desired molecules based on their optical spectra performance. We applied it to investigate a large collection of potential OPV materials, which were from the CEPDB database set up by the Harvard Clean Energy Project. Time dependent density functional theory (TD-DFT) modeling was used to calculate the absorption spectra of the molecules. Then based on the parameter, we screened out the top performing molecules for their potential OPV usage and suggested experimental efforts toward their synthesis. In addition, from those molecules, we summarized the functional groups that provided molecules certain spectrum capability. It is hoped that useful information could be mined out to provide hints to molecular design of OPV materials.

  2. Nanostructured interfaces for enhancing mechanical properties of composites: Computational micromechanical studies

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon

    2015-01-01

    Computational micromechanical studies of the effect of nanostructuring and nanoengineering of interfaces, phase and grain boundaries of materials on the mechanical properties and strength of materials and the potential of interface nanostructuring to enhance the materials properties are reviewed....

  3. Error Mitigation in Computational Design of Sustainable Energy Materials

    DEFF Research Database (Denmark)

    Christensen, Rune

    by individual C=O bonds. Energy corrections applied to C=O bonds significantly reduce systematic errors and can be extended to adsorbates. A similar study is performed for intermediates in the oxygen evolution and oxygen reduction reactions. An identified systematic error on peroxide bonds is found to also...... be present in the OOH* adsorbate. However, the systematic error will almost be canceled by inclusion of van der Waals energy. The energy difference between key adsorbates is thus similar to that previously found. Finally, a method is developed for error estimation in computationally inexpensive neural...

  4. Non-Print Social Studies Materials--Elementary School Level.

    Science.gov (United States)

    Lynn, Karen

    Types of non-print social studies materials developed for presentation to, and use by, elementary school students are identified. "Non-print" materials include films, filmstrips, video cassettes, audio recordings, computer databases, telecommunications, and hypertext. An explanation of why elementary school students can benefit from the use of…

  5. Computational modelling of Er(3+): Garnet laser materials

    Science.gov (United States)

    Spangler, Lee H.

    1994-01-01

    The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host

  6. Department of Material Studies - Overview

    International Nuclear Information System (INIS)

    Werner, Z.

    2007-01-01

    The technology of modifying surfaces of practical-use materials by means of continuous and pulsed energy and particle beams has been intensely studied for more than 20 years. In some fields it is presently utilized on a wide scale in industry. Continuous or pulsed ion and plasma beams play a significant role among various approaches used in this area. The research carried by Department P-IX is centered around the use of two own ion implantation machines (ion implanters) of different kind and several world-wide unique sources of high-intensity intense plasma pulses, utilized jointly with Department P-V. The Department cooperates closely with Forschungszentrum Rossendorf (FZR, Dresden, Germany) in the field of ion-beam-based analytical techniques and the use of unique ion implantation facilities. The main objectives of the Department are: search for new ways of modifying surface properties of solid materials by means of continuous or pulsed ion and plasma beams and implementation of ion implantation technique in national industries as a method of improving the lifetime of machine parts and tools utilized in industry. In 2006 these objectives were accomplished in many ways, particularly by research on: formation of superconducting MgB 2 phases, electrical conductivity in metallic nano-layers produced in oxide insulators (Al 2 O 3 ) by ion implantation, ion implantation as a method of improving mechanical properties of stainless steels without degrading their corrosion resistance, ion implantation/plasma treatment of ceramics aimed at improving their wettability in ceramic-metal joints, methods of controlling wear of ceramic-polymer pairs used in bio-medical applications. The research was conducted in cooperation with Department P-V of IPJ, Institute of Nuclear Chemistry and Technology (Warsaw), Warsaw University of Technology, Institute of Technology of Materials for Electronics (Warsaw), and Institute of Molecular Physics Polish Academy of Sciences (Poznan

  7. Department of Material Studies - Overview

    International Nuclear Information System (INIS)

    Werner, Z.

    2009-01-01

    Full text: The technology of modifying surfaces of technological materials by means of continuous and pulsed energy and particle beams has been intensely studied for more than 20 years. In some fields, it is currently utilized on a wide scale in industry. Continuous or pulsed ion and plasma beams play a significant role among various approaches used in this area. The research carried by Department P-IX is centered on applications of our two ion implantation facilities (ion implanters) of different kinds and unique sources of high-intensity intense plasma pulses, operated by the Department of Plasma Physics. The Department cooperates closely with Forschungszentrum Rossendorf (FZR, Dresden, Germany) in the field of analytical ion beam techniques and the use of unique ion implantation facilities. The main objectives of the Department are: · the search for new ways of modifying the surface properties of solid materials by means of continuous or pulsed ion and plasma beams and · the implementation of ion implantation techniques in national industries as a method of improving the lifetime of machine parts and tools utilized in industry. In 2008, research was focused on: · ion implantation/plasma treatment of ceramics aimed at improving their wettability in ceramic-metal joints, · ion beam synthesis and plasma pulse activation of superconducting MgB 2 phases, · cobalt and zirconium inclusions in conducting layers produced in oxide insulators (Al 2 O 3 ) by ion implantation and thermal annealing. Research was conducted in cooperation with Department P-V of IPJ, Institute of Nuclear Chemistry and Technology (Warsaw), Warsaw University of Technology, Institute of Technology of Materials for Electronics (Warsaw), Institute of Molecular Physics, Polish Academy of Sciences (Poznan), Institute of Chemical Physics PAS and Forschungszentrum Rossendorf FZR (Dresden, Germany), as well as with some industrial companies. (author)

  8. Computation material science of structural-phase transformation in casting aluminium alloys

    Science.gov (United States)

    Golod, V. M.; Dobosh, L. Yu

    2017-04-01

    Successive stages of computer simulation the formation of the casting microstructure under non-equilibrium conditions of crystallization of multicomponent aluminum alloys are presented. On the basis of computer thermodynamics and heat transfer during solidification of macroscale shaped castings are specified the boundary conditions of local heat exchange at mesoscale modeling of non-equilibrium formation the solid phase and of the component redistribution between phases during coalescence of secondary dendrite branches. Computer analysis of structural - phase transitions based on the principle of additive physico-chemical effect of the alloy components in the process of diffusional - capillary morphological evolution of the dendrite structure and the o of local dendrite heterogeneity which stochastic nature and extent are revealed under metallographic study and modeling by the Monte Carlo method. The integrated computational materials science tools at researches of alloys are focused and implemented on analysis the multiple-factor system of casting processes and prediction of casting microstructure.

  9. Department of Material Studies: Overview

    International Nuclear Information System (INIS)

    Werner, Z.

    2003-01-01

    Full text: The technology of modifying surfaces of industrial-use materials by means of continuous and pulsed energy beams has been intensely studied for more than 20 years. In some fields it is presently utilized on a broad scale in industry. Continuous or pulsed ion and plasma beams play a significant role among various approaches used. Department P-IX (jointly with Department P-V) utilizes some globally unique sources of intense plasma pulses, and jointly with Forschungszentrum Rossendorf (FZR, Dresden, Germany) conducts research on the application of continuous ion beams using FZR and IPJ facilities. The main objectives of the Department are: - a search for new ways of modifying surface properties of solid materials by means of pulsed plasma beams; - the implementation of ion implantation technique in national industries as a method of improving the lifetime of machine parts and tools utilized in industry. In 2002 these objectives were accomplished in many ways, particularly by research on phase changes in steel irradiated with intense pulsed plasma beams, Si-implanted TiN coatings on steel, implantation of high doses of nitrogen into aluminum, and corrosion properties of Ti surfaces alloyed with Pd by implantation and/or plasma pulses. The research was aimed at practical objectives like finding novel hard coatings, improving resistance to high temperature oxidation, reducing friction between NC6 steel-made parts without using a lubricating agent etc. The research was conducted in cooperation with Department P-V of IPJ, Institute of Nuclear Chemistry and Technology (Warsaw), Warsaw University of Technology, Institute of Technology of Materials for Electronics (Warsaw), Forschungszentrum Rossendorf FZR (Dresden, Germany), as well as with some industrial companies. Some research in 2002 was aimed at improving of the rod plasma injector generator used in our lab (the mechanism of electrode erosion during the plasma discharge, ablation of substrate material induced

  10. Editorial: Modelling and computational challenges in granular materials

    NARCIS (Netherlands)

    Weinhart, Thomas; Thornton, Anthony Richard; Einav, Itai

    2015-01-01

    This is the editorial for the special issue on “Modelling and computational challenges in granular materials” in the journal on Computational Particle Mechanics (CPM). The issue aims to provide an opportunity for physicists, engineers, applied mathematicians and computational scientists to discuss

  11. Computational Nanotechnology of Molecular Materials, Electronics, and Actuators with Carbon Nanotubes and Fullerenes

    Science.gov (United States)

    Srivastava, Deepak; Menon, Madhu; Cho, Kyeongjae; Biegel, Bryan (Technical Monitor)

    2001-01-01

    The role of computational nanotechnology in developing next generation of multifunctional materials, molecular scale electronic and computing devices, sensors, actuators, and machines is described through a brief review of enabling computational techniques and few recent examples derived from computer simulations of carbon nanotube based molecular nanotechnology.

  12. Computational Studies of Ionic Liquids

    National Research Council Canada - National Science Library

    Boatz, Jerry

    2004-01-01

    The structures and relative energies of the six possible N-protonated structures of the 1,5-diamino-1,2,3,4-tetrazolium cation have been computed at the B3LYP(3)/6-311G(d,p) and MP2/6-311G(d,p) levels of theory...

  13. International Conference: Computer-Aided Design of High-Temperature Materials

    National Research Council Canada - National Science Library

    Kalia, Rajiv

    1998-01-01

    .... The conference was attended by experimental and computational materials scientists, and experts in high performance computing and communications from universities, government laboratories, and industries in the U.S., Europe, and Japan...

  14. The use of computers in a materials science laboratory

    Science.gov (United States)

    Neville, J. P.

    1990-01-01

    The objective is to make available a method of easily recording the microstructure of a sample by means of a computer. The method requires a minimum investment and little or no instruction on the operation of a computer. An outline of the setup involving a black and white TV camera, a digitizer control box, a metallurgical microscope and a computer screen, printer, and keyboard is shown.

  15. IMPACT TESTING OF MATERIALS USING AN EIGHT-INCH AIR GUN AND COMPUTER REDUCTION OF DATA

    Energy Technology Data Exchange (ETDEWEB)

    Thorne, L. F.

    1973-10-01

    A mechanical shock actuator has been converted into an air gun capable of firing 8-inch-·diameter (20.32 cm) projectiles to velocities exceeding 1000 fps (304.8 m/ s). This new capability has been used to study the effect of impact velocity upon the energy.absorbed by crushable materials. Shockpulse data is reduced by computer techniques and test results are displayed in either tabular or graphic format by use of the C DC 6600 Calcomp plotter.

  16. Computer modelling of structures with account of the construction stages and the time dependent material properties

    Directory of Open Access Journals (Sweden)

    Traykov Alexander

    2015-01-01

    Full Text Available Numerical studies are performed on computer models taking into account the stages of construction and time dependent material properties defined in two forms. A 2D model of three storey two spans frame is created. The first form deals with material defined in the usual design practice way - without taking into account the time dependent properties of the concrete. The second form creep and shrinkage of the concrete are taken into account. Displacements and internal forces in specific elements and sections are reported. The influence of the time dependent material properties on the displacement and the internal forces in the main structural elements is tracked down. The results corresponding to the two forms of material definition are compared together as well as with the results obtained by the usual design calculations. Conclusions on the influence of the concrete creep and shrinkage during the construction towards structural behaviour are made.

  17. EXAFS studies of metamict materials

    International Nuclear Information System (INIS)

    Greegor, R.B.; Lytle, F.W.; Ewing, R.C.; Haaker, R.F.

    1984-01-01

    An important approach in the evaluation of crystalline wasteforms for nuclear waste storage is to study the long term stabilities of closely related radioactive mineral species which have become metamict (radiation damaged) and have been exposed to weathering processes for geologic periods of time. The metamictization and alteration effects can then be used for comparison with the results of short term laboratory leaching and irradiation experiments which have been designed to simulate long term effects. Phosphates, the Ti-Nb-Ta complex oxide minerals and various selected silicates are natural analogues for phases in proposed radioactive wasteforms. Because of the geochemical similarities with wasteforms, a study of the metamict state and annealing in complex mineral phosphates, silicates and oxides will yield data that is important in evaluating the long term stability of radioactive wasteforms. The investigation reported here is an application of EXAFS and XANES spectroscopy to the study of the structure of the metamict state. The nearest neighbor environment of Ti and Ca in metamict AB 2 O 6 -type complex oxides has been examined using SSRL Beam Line VII-3 in order to evaluate the effect of alpha-recoil damage on these structures. Comparison of the EXAFS/XANES data for metamict samples with data for annealed and crystalline samples suggests minor changes in the first coordination sphere, Ca-O or Ti-O, (a slight decrease in coordination number and bond lengths, and increased distortion of the coordination polyhedron), but major disruption of the second coordination sphere, for the material in the metamict state. These data suggest a mechanism for the transition from the crystalline to the metamict state in which tilting of cation coordiantion polyhedra is a possible effect of damage caused by alpha-recoil events

  18. Ab Initio Studies of Metal Hexaboride Materials

    Science.gov (United States)

    Schmidt, Kevin M.

    Metal hexaborides are refractory ceramics with several qualities relevant to materials design, such as low work functions, high hardness, low thermal expansion coefficients, and high melting points, among many other properties of interest for industrial applications. Thermal and mechanical stability is a common feature provided by the covalently-bonded network boron atoms, and electronic properties can vary significantly with the resident metal. While these materials are currently employed as electron emitters and abrasives, promising uses of these materials also include catalytic applications for chemical dissociation reactions of various molecules such as hydrogen, water and carbon monoxide, for example. However, these extensions require a thorough understanding of particular mechanical and electronic properties. This dissertation is a collection of studies focused on understanding the behavior of metal hexaboride materials using computational modeling methods to investigate materials properties of these from both classical and quantum mechanical points of view. Classical modeling is performed using molecular dynamics methods with interatomic potentials obtained from density functional theory (DFT) calculations. Atomic mean-square displacements from the quasi-harmonic approximation and lattice energetic data are produced with DFT for developing the potentials. A generalized method was also developed for the inversion of cohesive energy curves of crystalline materials; pairwise interatomic potentials are extracted using detailed geometrical descriptions of the atomic interactions and a list of atomic displacements and degeneracies. The surface structure of metal hexaborides is studied with DFT using several model geometries to describe the terminal cation layouts, and these provide a basis for further studies on metal hexaboride interactions with hydrogen. The surface electronic structure calculations show that segregated regions of metal and boron

  19. Computational methods for 2D materials: discovery, property characterization, and application design.

    Science.gov (United States)

    Paul, J T; Singh, A K; Dong, Z; Zhuang, H; Revard, B C; Rijal, B; Ashton, M; Linscheid, A; Blonsky, M; Gluhovic, D; Guo, J; Hennig, R G

    2017-11-29

    The discovery of two-dimensional (2D) materials comes at a time when computational methods are mature and can predict novel 2D materials, characterize their properties, and guide the design of 2D materials for applications. This article reviews the recent progress in computational approaches for 2D materials research. We discuss the computational techniques and provide an overview of the ongoing research in the field. We begin with an overview of known 2D materials, common computational methods, and available cyber infrastructures. We then move onto the discovery of novel 2D materials, discussing the stability criteria for 2D materials, computational methods for structure prediction, and interactions of monolayers with electrochemical and gaseous environments. Next, we describe the computational characterization of the 2D materials' electronic, optical, magnetic, and superconducting properties and the response of the properties under applied mechanical strain and electrical fields. From there, we move on to discuss the structure and properties of defects in 2D materials, and describe methods for 2D materials device simulations. We conclude by providing an outlook on the needs and challenges for future developments in the field of computational research for 2D materials.

  20. Fundamental Hyperelastic Material Study Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This research is part of an innovative effort to use hyperelastic materials to produce flexible and seamless aircraft structures that reduce drag and...

  1. Computing camera heading: A study

    Science.gov (United States)

    Zhang, John Jiaxiang

    2000-08-01

    An accurate estimate of the motion of a camera is a crucial first step for the 3D reconstruction of sites, objects, and buildings from video. Solutions to the camera heading problem can be readily applied to many areas, such as robotic navigation, surgical operation, video special effects, multimedia, and lately even in internet commerce. From image sequences of a real world scene, the problem is to calculate the directions of the camera translations. The presence of rotations makes this problem very hard. This is because rotations and translations can have similar effects on the images, and are thus hard to tell apart. However, the visual angles between the projection rays of point pairs are unaffected by rotations, and their changes over time contain sufficient information to determine the direction of camera translation. We developed a new formulation of the visual angle disparity approach, first introduced by Tomasi, to the camera heading problem. Our new derivation makes theoretical analysis possible. Most notably, a theorem is obtained that locates all possible singularities of the residual function for the underlying optimization problem. This allows identifying all computation trouble spots beforehand, and to design reliable and accurate computational optimization methods. A bootstrap-jackknife resampling method simultaneously reduces complexity and tolerates outliers well. Experiments with image sequences show accurate results when compared with the true camera motion as measured with mechanical devices.

  2. Use of computed tomography in nondestructive testing of polymeric materials

    International Nuclear Information System (INIS)

    Persson, S.; Oestman, E.

    1985-01-01

    Computed tomography has been used to detect imperfections and to measure cross-link density gradients in polymeric products, such as airplane tires, rubber shock absorbers, and filament-wound high-pressure tanks

  3. Computed tomography assessment of the efficiency of different techniques for removal of root canal filling material

    International Nuclear Information System (INIS)

    Dall'agnol, Cristina; Barletta, Fernando Branco; Hartmann, Mateus Silveira Martins

    2008-01-01

    This study evaluated the efficiency of different techniques for removal of filling material from root canals, using computed tomography (CT). Sixty mesial roots from extracted human mandibular molars were used. Root canals were filled and, after 6 months, the teeth were randomly assigned to 3 groups, according to the root-filling removal technique: Group A - hand instrumentation with K-type files; Group B - reciprocating instrumentation with engine-driven K-type files; and Group C rotary instrumentation with engine-driven ProTaper system. CT scans were used to assess the volume of filling material inside the root canals before and after the removal procedure. In both moments, the area of filling material was outlined by an experienced radiologist and the volume of filling material was automatically calculated by the CT software program. Based on the volume of initial and residual filling material of each specimen, the percentage of filling material removed from the root canals by the different techniques was calculated. Data were analyzed statistically by ANOVA and chi-square test for linear trend (α=0.05). No statistically significant difference (p=0.36) was found among the groups regarding the percent means of removed filling material. The analysis of the association between the percentage of filling material removal (high or low) and the proposed techniques by chi-square test showed statistically significant difference (p=0.015), as most cases in group B (reciprocating technique) presented less than 50% of filling material removed (low percent removal). In conclusion, none of the techniques evaluated in this study was effective in providing complete removal of filling material from the root canals. (author)

  4. Computed tomography assessment of the efficiency of different techniques for removal of root canal filling material

    Energy Technology Data Exchange (ETDEWEB)

    Dall' agnol, Cristina; Barletta, Fernando Branco [Lutheran University of Brazil, Canoas, RS (Brazil). Dental School. Dept. of Dentistry and Endodontics]. E-mail: fbarletta@terra.com.br; Hartmann, Mateus Silveira Martins [Uninga Dental School, Passo Fundo, RS (Brazil). Postgraduate Program in Dentistry

    2008-07-01

    This study evaluated the efficiency of different techniques for removal of filling material from root canals, using computed tomography (CT). Sixty mesial roots from extracted human mandibular molars were used. Root canals were filled and, after 6 months, the teeth were randomly assigned to 3 groups, according to the root-filling removal technique: Group A - hand instrumentation with K-type files; Group B - reciprocating instrumentation with engine-driven K-type files; and Group C rotary instrumentation with engine-driven ProTaper system. CT scans were used to assess the volume of filling material inside the root canals before and after the removal procedure. In both moments, the area of filling material was outlined by an experienced radiologist and the volume of filling material was automatically calculated by the CT software program. Based on the volume of initial and residual filling material of each specimen, the percentage of filling material removed from the root canals by the different techniques was calculated. Data were analyzed statistically by ANOVA and chi-square test for linear trend ({alpha}=0.05). No statistically significant difference (p=0.36) was found among the groups regarding the percent means of removed filling material. The analysis of the association between the percentage of filling material removal (high or low) and the proposed techniques by chi-square test showed statistically significant difference (p=0.015), as most cases in group B (reciprocating technique) presented less than 50% of filling material removed (low percent removal). In conclusion, none of the techniques evaluated in this study was effective in providing complete removal of filling material from the root canals. (author)

  5. COMPARATIVE STUDY OF CLOUD COMPUTING AND MOBILE CLOUD COMPUTING

    OpenAIRE

    Nidhi Rajak*, Diwakar Shukla

    2018-01-01

    Present era is of Information and Communication Technology (ICT) and there are number of researches are going on Cloud Computing and Mobile Cloud Computing such security issues, data management, load balancing and so on. Cloud computing provides the services to the end user over Internet and the primary objectives of this computing are resource sharing and pooling among the end users. Mobile Cloud Computing is a combination of Cloud Computing and Mobile Computing. Here, data is stored in...

  6. Computational Design of New Materials for Ammonia Storage

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Quaade, Ulrich

    alkaline-earth mixture, Ba4CaSr3Cl16 wasidentified, and the predicted release was verified experimentally. The two bestfound candidates, Ca4Cu2Y2Cl16 and Sr4Cu2Y2Cl16, are examples of materials,one would not suggest using chemical intuition. This shows that thealgorithm is able to identify new materials...

  7. Computer information resources of inorganic chemistry and materials science

    Energy Technology Data Exchange (ETDEWEB)

    Kiselyova, N N; Dudarev, V A; Zemskov, V S [A.A.Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Moscow (Russian Federation)

    2010-02-28

    Information systems used in inorganic chemistry and materials science are considered. The following basic trends in the development of modern information systems in these areas are highlighted: access to information via the Internet, merging of documental and factual databases, involvement of experts in the evaluation of the data reliability, supplementing databases with information analysis tools on the properties of inorganic substances and materials.

  8. Composite materials with arbitrary geometry - computer analysis with MATMEC

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    1999-01-01

    Text note for the Summer school on "Hydration and Microstructure of High Performance Concrete, held at Dept. Struct. Eng. and Materials, DTU.......Text note for the Summer school on "Hydration and Microstructure of High Performance Concrete, held at Dept. Struct. Eng. and Materials, DTU....

  9. Computer information resources of inorganic chemistry and materials science

    International Nuclear Information System (INIS)

    Kiselyova, N N; Dudarev, V A; Zemskov, V S

    2010-01-01

    Information systems used in inorganic chemistry and materials science are considered. The following basic trends in the development of modern information systems in these areas are highlighted: access to information via the Internet, merging of documental and factual databases, involvement of experts in the evaluation of the data reliability, supplementing databases with information analysis tools on the properties of inorganic substances and materials.

  10. Challenges in computational materials science: Multiple scales, multi-physics and evolving discontinuities

    NARCIS (Netherlands)

    Borst, de R.

    2008-01-01

    Novel experimental possibilities together with improvements in computer hardware as well as new concepts in computational mathematics and mechanics in particular multiscale methods are now, in principle, making it possible to derive and compute phenomena and material parameters at a macroscopic

  11. Computational Design and Characterization of New Battery Materials

    DEFF Research Database (Denmark)

    Mýrdal, Jón Steinar Garðarsson

    . It is hoped that high energy dense Li-air batteries will be able to replace Li-ion batteries in the future. There are however number of challenge that need to be solved before that can happen. We have studied the growth and decomposition of Li2O2, which is the main discharge product of Li-O2batteries......This thesis is dedicated to the investigation and design of new functional materials for energy storage. The focus of the presented work is on components for the successful Li-ion and the promising Li-air batteries. First principle density function theory calculations are applied to screening...... electrolytes are believed to increase safety in Li based batteries as they would prevent metallic growth in the electrolyte. LiBH4 has a solid superionic conducting HT phase that is stable above 390 K. The HT phase can be stabilized at room temperature with substitution of I into the LiBH4 structure. Here we...

  12. Computational screening of new inorganic materials for highly efficient solar energy conversion

    DEFF Research Database (Denmark)

    Kuhar, Korina

    2017-01-01

    in solar cells convert solar energy into electricity, and PC uses harvested energy to conduct chemical reactions, such as splitting water into oxygen and, more importantly, hydrogen, also known as the fuel of the future. Further progress in both PV and PC fields is mostly limited by the flaws in materials...... materials. In this work a high-throughput computational search for suitable absorbers for PV and PC applications is presented. A set of descriptors has been developed, such that each descriptor targets an important property or issue of a good solar energy conversion material. The screening study...... that we have access to. Despite the vast amounts of energy at our disposal, we are not able to harvest this solar energy efficiently. Currently, there are a few ways of converting solar power into usable energy, such as photovoltaics (PV) or photoelectrochemical generation of fuels (PC). PV processes...

  13. Computational Screening of Materials for Water Splitting Applications

    DEFF Research Database (Denmark)

    Castelli, Ivano Eligio

    Design new materials for energy production in a photoelectrochemical cell, where water is split into hydrogen and oxygen by solar light, is one possible solution to the problem of increasing energy demand and storage. A screening procedure based on ab-initio density functional theory calculations...... Project database, which is based on the experimental ICSD database, and the bandgaps were calculated with focus on finding materials with potential as light harvesters. 24 materials have been proposed for the one-photon water splitting and 23 for the two-photon mechanism. Another method to obtain energy...... from Sun is using a photovoltaic cell that converts solar light into electricity. The absorption spectra of 70 experimentally known compounds, that are expected to be useful for light-to-electricity generation, have been calculated. 17 materials have been predicted to be promising for a single...

  14. A Codesign Case Study in Computer Graphics

    DEFF Research Database (Denmark)

    Brage, Jens P.; Madsen, Jan

    1994-01-01

    The paper describes a codesign case study where a computer graphics application is examined with the intention to speed up its execution. The application is specified as a C program, and is characterized by the lack of a simple compute-intensive kernel. The hardware/software partitioning is based...

  15. Using computer technology to identify the appropriate radioactive materials packaging

    International Nuclear Information System (INIS)

    Driscoll, K.L.; Conan, M.R.

    1989-01-01

    The Radioactive Materials Packaging (RAMPAC) database is designed to store and retrieve information on all non-classified packages certified for the transport of radioactive materials within the boundaries of the US. The information in RAMPAC is publicly available, and the database has been designed so that individuals without programming experience can search for and retrieve information using a menu-driven system. RAMPAC currently contains information on over 650 radioactive material shipping packages. Information is gathered from the US Department of Energy (DOE), the US Department of transportation (DOT), and the US Nuclear Regulatory Commission (NRC). RAMPAC is the only tool available to radioactive material shippers that contains and reports packaging information from all three Federal Agencies. The DOT information includes package listings from Canada, France, Germany, Great Britain, and Japan, which have DOT revalidations for their certificates of competent authority and are authorized for use within the US for import and export shipments only. RAMPAC was originally developed in 1981 by DOE as a research and development tool. In recent years, however, RAMPAC has proven to be highly useful to operational personnel. As packages become obsolete or materials to be transported change, shippers of radioactive materials must be able to determine if alternative packages exist before designing new packages. RAMPAC is designed to minimize the time required to make this determination, thus assisting the operational community in meeting their goals

  16. Computational Quantum Mechanics for Materials Engineers The EMTO Method and Applications

    CERN Document Server

    Vitos, L

    2007-01-01

    Traditionally, new materials have been developed by empirically correlating their chemical composition, and the manufacturing processes used to form them, with their properties. Until recently, metallurgists have not used quantum theory for practical purposes. However, the development of modern density functional methods means that today, computational quantum mechanics can help engineers to identify and develop novel materials. Computational Quantum Mechanics for Materials Engineers describes new approaches to the modelling of disordered alloys that combine the most efficient quantum-level th

  17. Modelling Emission from Building Materials with Computational Fluid Dynamics

    DEFF Research Database (Denmark)

    Topp, Claus; Nielsen, Peter V.; Heiselberg, Per

    This paper presents a numerical model that by means of computational fluid dynamics (CFD) is capable of dealing with both pollutant transport across the boundary layer and internal diffusion in the source without prior knowledge of which is the limiting process. The model provides the concentration...

  18. Beller Lectureship: Materials for Li & Na Batteries :A Computational Materials Science Point of View

    Science.gov (United States)

    Ahuja, Rajeev

    Energy storage has been a theme for scientists for two hundred years. The Lead acid battery research on batteries occupied some of the best minds of 19th century. Plante in 1859 invented lead acid battery which starts your car and ignites internal combustion which takes over the propulsion. Although the lead battery is over 150 years old but the origin of its open circuit voltage (OCV) of 2.1 V is still known. In present talk, I will show how one can explain the origin of OCV of 2.1 V based on foundations of relativistic quantum mechanics. Surprisingly, seems to be the first time its chemistry has been theoretically modeled from the first principles. The main message of this work is that most of the electro-motoric force of the common lead battery comes from relativistic effects. In second part, I will provide an overview of the most recent theoretical studies undertaken by us in the field of materials for Li & Na ion batteries. For selected examples, I will show how ab initio calculations can be of use in the effort to reach a better understanding of battery materials and to occasionally also guide the search for new promising materials.

  19. Computer stress study of bone with computed tomography

    International Nuclear Information System (INIS)

    Linden, M.J.; Marom, S.A.; Linden, C.N.

    1986-01-01

    A computer processing tool has been developed which, together with a finite element program, determines the stress-deformation pattern in a long bone, utilizing Computed Tomography (CT) data files for the geometry and radiographic density information. The geometry, together with mechanical properties and boundary conditions: loads and displacements, comprise the input of the Finite element (FE) computer program. The output of the program is the stresses and deformations in the bone. The processor is capable of developing an accurate three-dimensional finite element model from a scanned human long bone due to the CT high pixel resolution and the local mechanical properties determined from the radiographic densities of the scanned bone. The processor, together with the finite element program, serves first as an analysis tool towards improved understanding of bone function and remodelling. In this first stage, actual long bones may be scanned and analyzed under applied loads and displacements, determined from existing gait analyses. The stress-deformation patterns thus obtained may be used for studying the biomechanical behavior of particular long bones such as bones with implants and with osteoporosis. As a second stage, this processor may serve as a diagnostic tool for analyzing the biomechanical response of a specific patient's long long bone under applied loading by utilizing a CT data file of the specific bone as an input to the processor with the FE program

  20. Mechanical behavior of nanotwinned materials – experimental and computational approaches

    Energy Technology Data Exchange (ETDEWEB)

    Yavas, Hakan [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    Nanotwinned materials exhibit high strength combined with excellent thermal stability, making them potentially attractive for numerous applications. When deposited on cold substrates at high rates, for example, silver films can be prepared with a high-density of growth twins with an average twin boundary spacing of less than 10 nm. These films show a very strong {111} texture, with the twin boundaries being perpendicular to the growth direction. The origins of superior mechanical and thermal properties of nanotwinned materials, however, are not yet fully understood and need further improvements.

  1. Application of computer simulation in the stereology of materials

    Czech Academy of Sciences Publication Activity Database

    Saxl, Ivan; Ponížil, P.; Löflerová, M.

    2009-01-01

    Roč. 4, č. 2 (2009), s. 231-249 ISSN 1741-8410 R&D Projects: GA ČR GA201/06/0302 Grant - others:GA ČR(CZ) GA106/05/0550 Institutional research plan: CEZ:AV0Z10190503 Keywords : 3D computer simulation * fibre anisotropy * fracture surface * grain size estimation * random tessellation * rough surface analysis * fibre processes Subject RIV: BA - General Mathematics

  2. High School Students' Written Argumentation Qualities with Problem-Based Computer-Aided Material (PBCAM) Designed about Human Endocrine System

    Science.gov (United States)

    Vekli, Gülsah Sezen; Çimer, Atilla

    2017-01-01

    This study investigated development of students' scientific argumentation levels in the applications made with Problem-Based Computer-Aided Material (PBCAM) designed about Human Endocrine System. The case study method was used: The study group was formed of 43 students in the 11th grade of the science high school in Rize. Human Endocrine System…

  3. Computational studies of BEGe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Salathe, Marco [Max Planck Institut fuer Kernphysik, Heidelberg (Germany)

    2013-07-01

    The GERDA experiment searches for the neutrinoless double beta decay within the active volume of germanium detectors. Simulations of the physical processes within such detectors are vital to gain a better understanding of the measurements. The simulation procedure follows three steps: First it calculates the electric potential, next it simulates the electron and hole drift within the germanium crystal and finally it generates a corresponding signal. The GERDA collaboration recently characterized newly produced Broad Energy Germanium Detectors (BEGe) in the HADES underground laboratory in Mol, Belgium. A new pulse shape simulation library was established to examine the results of these measurements. The library has also proven to be a very powerful tool for other applications such as detector optimisation studies. The pulse shape library is based on ADL 3.0 (B. Bruyneel, B. Birkenbach, http://www.ikp.uni-koeln.de/research/agata/download.php) and m3dcr (D. Radford, http://radware.phy.ornl.gov/MJ/m3dcr).

  4. Computational Studies of Drug Resistance

    DEFF Research Database (Denmark)

    da Silva Martins, João Miguel

    Drug resistance has been an increasing problem in patient treatment and drug development. Starting in the last century and becoming a major worry in the medical and scienti c communities in the early part of the current millennium, major research must be performed to address the issues of viral...... is of the utmost importance in developing better and less resistance-inducing drugs. A drug's in uence can be characterized in many diff erent ways, however, and the approaches I take in this work re ect those same different in uences. This is what I try to achieve in this work, through seemingly unrelated...... approaches that come together in the study of drug's and their in uence on proteins and vice-versa. In part I, I aim to understand through combined theoretical ensemble analysis and free energy calculations the e ects mutations have over the binding anity and function of the M2 proton channel. This research...

  5. Research study of conjugate materials; Conjugate material no chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    The paper reported an introductory research on possibilities of new glass `conjugate materials.` The report took up the structure and synthetic process of conjugate materials to be researched/developed, classified them according to structural elements on molecular, nanometer and cluster levels, and introduced the structures and functions. Further, as glasses with new functions to be proposed, the paper introduced transparent and high-strength glass used for houses and vehicles, light modulation glass which realizes energy saving and optical data processing, and environmentally functional glass which realizes environmental cleaning or high performance biosensor. An initial survey was also conducted on rights of intellectual property to be taken notice of in Japan and abroad in the present situation. Reports were summed up and introduced of Osaka National Research Institute, Electrotechnical Laboratory, and National Industrial Research Institute of Nagoya which are all carrying out leading studies of conjugate materials. 235 refs., 135 figs., 6 tabs.

  6. Computational simulation of laser heat processing of materials

    Science.gov (United States)

    Shankar, Vijaya; Gnanamuthu, Daniel

    1987-04-01

    A computational model simulating the laser heat treatment of AISI 4140 steel plates with a CW CO2 laser beam has been developed on the basis of the three-dimensional, time-dependent heat equation (subject to the appropriate boundary conditions). The solution method is based on Newton iteration applied to a triple-approximate factorized form of the equation. The method is implicit and time-accurate; the maintenance of time-accuracy in the numerical formulation is noted to be critical for the simulation of finite length workpieces with a finite laser beam dwell time.

  7. Computational dynamics of laser alloyed metallic materials for improved corrosion performance: computational dynamics of laser alloyed metallic materials

    CSIR Research Space (South Africa)

    Fatoba, OS

    2016-04-01

    Full Text Available Laser alloying is a material processing method which utilizes the high power density available from defocused laser beam to melt both metal coatings and a part of the underlying substrate. Since melting occur solitary at the surface, large...

  8. Efficient technique for computational design of thermoelectric materials

    Science.gov (United States)

    Núñez-Valdez, Maribel; Allahyari, Zahed; Fan, Tao; Oganov, Artem R.

    2018-01-01

    Efficient thermoelectric materials are highly desirable, and the quest for finding them has intensified as they could be promising alternatives to fossil energy sources. Here we present a general first-principles approach to predict, in multicomponent systems, efficient thermoelectric compounds. The method combines a robust evolutionary algorithm, a Pareto multiobjective optimization, density functional theory and a Boltzmann semi-classical calculation of thermoelectric efficiency. To test the performance and reliability of our overall framework, we use the well-known system Bi2Te3-Sb2Te3.

  9. Subglacial sediment mechanics investigated by computer simulation of granular material

    DEFF Research Database (Denmark)

    Damsgaard, Anders; Egholm, David Lundbek; Tulaczyk, Slawek

    The mechanical properties of subglacial sediments are known to directly influence the stability of ice streams and fast-moving glaciers, but existing models of granular sediment deformation are poorly constrained. In addition, upscaling to generalized mathematical models is difficult due to the m......The mechanical properties of subglacial sediments are known to directly influence the stability of ice streams and fast-moving glaciers, but existing models of granular sediment deformation are poorly constrained. In addition, upscaling to generalized mathematical models is difficult due....... The numerical method is applied to better understand the mechanical properties of the subglacial sediment and its interaction with meltwater. The computational approach allows full experimental control and offers insights into the internal kinematics, stress distribution, and mechanical stability. During...

  10. Digital Materialisms: Frameworks for Digital Media Studies

    OpenAIRE

    Casemajor, Nathalie

    2015-01-01

    Since the 1980s, digital materialism has received increasing interest in the field of media studies. Materialism as a theoretical paradigm assumes that all things in the world are tied to physical processes and matter. Yet within digital media studies, the understanding of what should be the core object of a materialist analysis is debated. This paper proposes to untangle some of the principal theoretical propositions that compose the field of digital materialism. It outlines six frameworks t...

  11. Experimental and computing strategies in advanced material characterization problems

    Energy Technology Data Exchange (ETDEWEB)

    Bolzon, G. [Department of Civil and Environmental Engineering, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano, Italy gabriella.bolzon@polimi.it (Italy)

    2015-10-28

    The mechanical characterization of materials relies more and more often on sophisticated experimental methods that permit to acquire a large amount of data and, contemporarily, to reduce the invasiveness of the tests. This evolution accompanies the growing demand of non-destructive diagnostic tools that assess the safety level of components in use in structures and infrastructures, for instance in the strategic energy sector. Advanced material systems and properties that are not amenable to traditional techniques, for instance thin layered structures and their adhesion on the relevant substrates, can be also characterized by means of combined experimental-numerical tools elaborating data acquired by full-field measurement techniques. In this context, parameter identification procedures involve the repeated simulation of the laboratory or in situ tests by sophisticated and usually expensive non-linear analyses while, in some situation, reliable and accurate results would be required in real time. The effectiveness and the filtering capabilities of reduced models based on decomposition and interpolation techniques can be profitably used to meet these conflicting requirements. This communication intends to summarize some results recently achieved in this field by the author and her co-workers. The aim is to foster further interaction between engineering and mathematical communities.

  12. Experimental and computing strategies in advanced material characterization problems

    International Nuclear Information System (INIS)

    Bolzon, G.

    2015-01-01

    The mechanical characterization of materials relies more and more often on sophisticated experimental methods that permit to acquire a large amount of data and, contemporarily, to reduce the invasiveness of the tests. This evolution accompanies the growing demand of non-destructive diagnostic tools that assess the safety level of components in use in structures and infrastructures, for instance in the strategic energy sector. Advanced material systems and properties that are not amenable to traditional techniques, for instance thin layered structures and their adhesion on the relevant substrates, can be also characterized by means of combined experimental-numerical tools elaborating data acquired by full-field measurement techniques. In this context, parameter identification procedures involve the repeated simulation of the laboratory or in situ tests by sophisticated and usually expensive non-linear analyses while, in some situation, reliable and accurate results would be required in real time. The effectiveness and the filtering capabilities of reduced models based on decomposition and interpolation techniques can be profitably used to meet these conflicting requirements. This communication intends to summarize some results recently achieved in this field by the author and her co-workers. The aim is to foster further interaction between engineering and mathematical communities

  13. RADTRAN II: revised computer code to analyze transportation of radioactive material

    International Nuclear Information System (INIS)

    Taylor, J.M.; Daniel, S.L.

    1982-10-01

    A revised and updated version of the RADTRAN computer code is presented. This code has the capability to predict the radiological impacts associated with specific schemes of radioactive material shipments and mode specific transport variables

  14. Dose computation of Ti activated products for its qualification as a material for the sample holder in FBTR

    International Nuclear Information System (INIS)

    Ashok Kumar, G.V.S.; Kumar, R.; Venkatasubramani, C.R.; Acharya, R.; Reddy, A.V.R.

    2014-01-01

    Development of a Fast flux experimental facility with a sample holder facility in FBTR has been envisaged to carry out the studies on i) fast neutron activation analysis and ii) fission studies. This paper describes the facility in detail and dose computations that are to be generated due to long irradiation of the material of the sample holder i.e. titanium. (author)

  15. Computational analysis of gas-solid interactions in materials for energy storage and conversion

    DEFF Research Database (Denmark)

    Lysgaard, Steen

    . The focus is specifically on the investigation of catalytic materials for electrochemical CO2 fixation into fuels as well as ammonia storage materials, using computational methods relying on density functional theory (DFT) and effective medium theory (EMT) calculations as well as a genetic algorithm....... Nanoparticles of binary alloys have previously been shown to be catalytically active for electrochemical CO2 fixation. The stability of the nanoparticles is critical for a catalytic system. We have developed a method to determine the structure and composition of nanoparticles under reactive conditions...... found in certain experiments. We have furthermore determined a stable surface state of ammonia in SrCl2 ammines and identified its implications on the ab- and desorption kinetics. Metal salts often bind ammonia and water molecules in a similar structural coordination. We have studied the competitive...

  16. US QCD computational performance studies with PERI

    International Nuclear Information System (INIS)

    Zhang, Y; Fowler, R; Huck, K; Malony, A; Porterfield, A; Reed, D; Shende, S; Taylor, V; Wu, X

    2007-01-01

    We report on some of the interactions between two SciDAC projects: The National Computational Infrastructure for Lattice Gauge Theory (USQCD), and the Performance Engineering Research Institute (PERI). Many modern scientific programs consistently report the need for faster computational resources to maintain global competitiveness. However, as the size and complexity of emerging high end computing (HEC) systems continue to rise, achieving good performance on such systems is becoming ever more challenging. In order to take full advantage of the resources, it is crucial to understand the characteristics of relevant scientific applications and the systems these applications are running on. Using tools developed under PERI and by other performance measurement researchers, we studied the performance of two applications, MILC and Chroma, on several high performance computing systems at DOE laboratories. In the case of Chroma, we discuss how the use of C++ and modern software engineering and programming methods are driving the evolution of performance tools

  17. Computational techniques in tribology and material science at the atomic level

    Science.gov (United States)

    Ferrante, J.; Bozzolo, G. H.

    1992-01-01

    Computations in tribology and material science at the atomic level present considerable difficulties. Computational techniques ranging from first-principles to semi-empirical and their limitations are discussed. Example calculations of metallic surface energies using semi-empirical techniques are presented. Finally, application of the methods to calculation of adhesion and friction are presented.

  18. Teaching Concept Mapping and University Level Study Strategies Using Computers.

    Science.gov (United States)

    Mikulecky, Larry; And Others

    1989-01-01

    Assesses the utility and effectiveness of three interactive computer programs and associated print materials in instructing and modeling for undergraduates how to comprehend and reconceptualize scientific textbook material. Finds that "how to" reading strategies can be taught via computer and transferred to new material. (RS)

  19. A computational framework for the optimal design of morphing processes in locally activated smart material structures

    International Nuclear Information System (INIS)

    Wang, Shuang; Brigham, John C

    2012-01-01

    A proof-of-concept study is presented for a strategy to obtain maximally efficient and accurate morphing structures composed of active materials such as shape memory polymers (SMP) through synchronization of adaptable and localized activation and actuation. The work focuses on structures or structural components entirely composed of thermo-responsive SMP, and particularly utilizes the ability of such materials to display controllable variable stiffness. The study presents and employs a computational inverse mechanics approach that combines a computational representation of the SMP thermo-mechanical behavior with a nonlinear optimization algorithm to determine location, magnitude and sequencing of the activation and actuation to obtain a desired shape change subject to design objectives such as prevention of damage. Two numerical examples are presented in which the synchronization of the activation and actuation and the location of activation excitation were optimized with respect to the combined thermal and mechanical energy for design concepts in morphing skeletal structural components. In all cases the concept of localized activation along with the optimal design strategy were able to produce far more energy efficient morphing structures and more accurately reach the desired shape change in comparison to traditional methods that require complete structural activation prior to actuation. (paper)

  20. Case Studies in Library Computer Systems.

    Science.gov (United States)

    Palmer, Richard Phillips

    Twenty descriptive case studies of computer applications in a variety of libraries are presented in this book. Computerized circulation, serial and acquisition systems in public, high school, college, university and business libraries are included. Each of the studies discusses: 1) the environment in which the system operates, 2) the objectives of…

  1. Methods for Computing Accurate Atomic Spin Moments for Collinear and Noncollinear Magnetism in Periodic and Nonperiodic Materials.

    Science.gov (United States)

    Manz, Thomas A; Sholl, David S

    2011-12-13

    The partitioning of electron spin density among atoms in a material gives atomic spin moments (ASMs), which are important for understanding magnetic properties. We compare ASMs computed using different population analysis methods and introduce a method for computing density derived electrostatic and chemical (DDEC) ASMs. Bader and DDEC ASMs can be computed for periodic and nonperiodic materials with either collinear or noncollinear magnetism, while natural population analysis (NPA) ASMs can be computed for nonperiodic materials with collinear magnetism. Our results show Bader, DDEC, and (where applicable) NPA methods give similar ASMs, but different net atomic charges. Because they are optimized to reproduce both the magnetic field and the chemical states of atoms in a material, DDEC ASMs are especially suitable for constructing interaction potentials for atomistic simulations. We describe the computation of accurate ASMs for (a) a variety of systems using collinear and noncollinear spin DFT, (b) highly correlated materials (e.g., magnetite) using DFT+U, and (c) various spin states of ozone using coupled cluster expansions. The computed ASMs are in good agreement with available experimental results for a variety of periodic and nonperiodic materials. Examples considered include the antiferromagnetic metal organic framework Cu3(BTC)2, several ozone spin states, mono- and binuclear transition metal complexes, ferri- and ferro-magnetic solids (e.g., Fe3O4, Fe3Si), and simple molecular systems. We briefly discuss the theory of exchange-correlation functionals for studying noncollinear magnetism. A method for finding the ground state of systems with highly noncollinear magnetism is introduced. We use these methods to study the spin-orbit coupling potential energy surface of the single molecule magnet Fe4C40H52N4O12, which has highly noncollinear magnetism, and find that it contains unusual features that give a new interpretation to experimental data.

  2. Transuranic Hybrid Materials: Crystallographic and Computational Metrics of Supramolecular Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Surbella, Robert G. [Department; Ducati, Lucas C. [Department; Pellegrini, Kristi L. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; McNamara, Bruce K. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Autschbach, Jochen [Department; Schwantes, Jon M. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Cahill, Christopher L. [Department

    2017-07-26

    A family of twelve supramolecular [AnO2Cl4]2- (An = U, Np, Pu) containing compounds assembled via hydrogen and halogen bonds donated by substituted 4-X-pyridinium cations (X = H, Cl, Br, I) is reported. These materials were prepared from a room-temperature synthesis wherein crystallization of unhydrolyzed and valence pure [An(VI)O2Cl4]2- (An = U, Np, Pu) tectons are the norm. We present a hierarchy of assembly criteria based on crystallographic observations, and subsequently quantify the strengths of the non-covalent interactions using Kohn-Sham density functional calculations. We provide, for the first time, a detailed description of the electrostatic potentials (ESPs) of the actinyl tetrahalide dianions and reconcile crystallographically observed structural motifs and non-covalent interaction (NCI) acceptor-donor pairings. Our findings indicate that the average electrostatic potential across the halogen ligands (the acceptors) changes by only ~2 kJ mol-1 across the AnO22+ series, indicating the magnitude of the potential is independent of the metal center. The role of the cation is therefore critical in directing structural motifs and dictating the resulting hydrogen and halogen bond strengths, the former being stronger due to the positive charge centralized on the pyridyl nitrogen N-H+. Subsequent analyses using the Quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) approaches support this conclusion and highlight the structure directing role of the cations. Whereas one can infer that the 2 Columbic attraction is the driver for assembly, the contribution of the non-covalent interaction is to direct the molecular-level arrangement (or disposition) of the tectons.

  3. Quantitative material decomposition using spectral computed tomography with an energy-resolved photon-counting detector

    International Nuclear Information System (INIS)

    Lee, Seungwan; Choi, Yu-Na; Kim, Hee-Joung

    2014-01-01

    Dual-energy computed tomography (CT) techniques have been used to decompose materials and characterize tissues according to their physical and chemical compositions. However, these techniques are hampered by the limitations of conventional x-ray detectors operated in charge integrating mode. Energy-resolved photon-counting detectors provide spectral information from polychromatic x-rays using multiple energy thresholds. These detectors allow simultaneous acquisition of data in different energy ranges without spectral overlap, resulting in more efficient material decomposition and quantification for dual-energy CT. In this study, a pre-reconstruction dual-energy CT technique based on volume conservation was proposed for three-material decomposition. The technique was combined with iterative reconstruction algorithms by using a ray-driven projector in order to improve the quality of decomposition images and reduce radiation dose. A spectral CT system equipped with a CZT-based photon-counting detector was used to implement the proposed dual-energy CT technique. We obtained dual-energy images of calibration and three-material phantoms consisting of low atomic number materials from the optimal energy bins determined by Monte Carlo simulations. The material decomposition process was accomplished by both the proposed and post-reconstruction dual-energy CT techniques. Linear regression and normalized root-mean-square error (NRMSE) analyses were performed to evaluate the quantitative accuracy of decomposition images. The calibration accuracy of the proposed dual-energy CT technique was higher than that of the post-reconstruction dual-energy CT technique, with fitted slopes of 0.97–1.01 and NRMSEs of 0.20–4.50% for all basis materials. In the three-material phantom study, the proposed dual-energy CT technique decreased the NRMSEs of measured volume fractions by factors of 0.17–0.28 compared to the post-reconstruction dual-energy CT technique. It was concluded that the

  4. Quasi-brittle material behavior under cyclic loading: from virtual testing to structural computation

    International Nuclear Information System (INIS)

    Vassaux, Maxime

    2015-01-01

    Macroscopic constitutive laws are developed not only because they allow for large-scale computations but also because refine dissipative mechanisms observed at lower scales. Within the framework of this study, the development of such models is carried out in the context of seismic loading, that is to say reverse cyclic loading, applied to the quasi-brittle materials and more precisely, concrete-like materials. Nowadays, robust and predictive macroscopic constitutive laws are still rare because of the complexity of cracking related phenomena. Among the challenges to face, the material parameters identification is far from being the easiest due to the lack of experimental data. Indeed, the difficulties to carry out cyclic tests on concrete-like materials are numerous. To overcome these difficulties, a virtual testing approach based on a refine model is proposed in this study in order to feed continuum models with the missing material parameters. Adopting a microscopic point of view, a representative volume element is seen as a structure. The microscopic model has been developed with the aim to require a minimal number of material parameters which only need basic mechanical tests to be identified. From an existing lattice model developed to deal with monotonic loading, several enhancements have been realized in order to extend its range of applicability, making it capable of dealing with complex multi-axial cyclic loadings. The microscopic model has been validated as a virtual testing machine that is able to help the identification procedure of continuous constitutive laws. This identification approach has been applied on a new constitutive law developed within the framework of isotropic continuum damage mechanics accounting for cyclic related effects. In particular, the concept of regularized unilateral effect has been introduced to describe the progressive crack closure. The macroscopic model has been calibrated with the help from the aforementioned virtual testing

  5. Human Perception, SBS Sympsoms and Performance of Office Work during Exposure to Air Polluted by Building Materials and Personal Computers

    DEFF Research Database (Denmark)

    Bako-Biro, Zsolt

    The present thesis deals with the impact of polluted air from building materials and personal computers on human perception, Sick Building Syndrome (SBS) symptoms and performance of office work. These effects have been studies in a series of experiments that are described in two different chapters...

  6. Material focus

    DEFF Research Database (Denmark)

    Sokoler, Tomas; Vallgårda, Anna K. A.

    2009-01-01

    In this paper we build on the notion of computational composites, which hold a material perspective on computational technology. We argue that a focus on the material aspects of the technology could be a fruitful approach to achieve new expressions and to gain a new view on the technology's role...... in design. We study two of the computer's material properties: computed causality and connectability and through developing two computational composites that utilize these properties we begin to explore their potential expressions....

  7. Computed Tomography Study Of Complicated Bacterial Meningitis ...

    African Journals Online (AJOL)

    To monitor the structural intracranial complications of bacterial meningitis using computed tomography (CT) scan. Retrospective study of medical and radiological records of patients who underwent CT scan over a 4 year period. AUniversityTeachingHospital in a developing country. Thirty three patients with clinically and ...

  8. Study on tritium recovery from breeder materials

    International Nuclear Information System (INIS)

    Moriyama, H.; Moritani, K.

    1997-01-01

    For the development of fusion reactor blanket systems, some of the key issues on the tritium recovery performance of solid and liquid breeder materials were studied. In the case of solid breeder materials, a special attention was focussed on the effects of irradiation on the tritium recovery performance, and tritium release experiments, luminescence measurements of irradiation defects and modeling studies were systematically performed. For liquid breeder materials, tritium recovery experiments from molten salt and liquid lithium were performed, and the technical feasibility of tritium recovery methods was discussed. (author)

  9. Computational Tools and Studies of Graphene Nanostructures

    DEFF Research Database (Denmark)

    Papior, Nick Rübner

    require revised algorithms. Furthermore, the advent of 2D materials may prove prominent in future nanoelectronics for electronic and heat transport devices. Such materials include the Nobel Prize winning material, graphene which has unique properties. The main focus of the work presented in this thesis...... example is used to highlight the importance of the quantum capacitance that is evident in low density of states systems. Additionally the gating method was used in nonequilibrium to study the gate-bias dependence on graphene nano-constrictions. This indicated a pinning effect arising due to differences...... in coupling strength between the device and the two electrodes. Two studies are presented using the non-equilibrium method with Ne = 3. First, graphene T-junctions are studied to uncover potential interconnects in future graphene based devices. This T-junction is studied under two non-equilibrium situations...

  10. Continuum Mechanical and Computational Aspects of Material Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Fried, Eliot [McGill Univ., Montreal, QC (Canada)

    2015-02-11

    Fluid flows are typically classified as laminar or turbulent. While the glassy, regular flow of water from a slightly opened tap is laminar, the sinuous, irregular flow of water from a fully opened tap is turbulent. In a laminar flow, the velocity and other relevant fields are deterministic functions of position and time. Photos taken at different times, no matter how far removed, of steady laminar flow from a tap will be identical. In a turbulent flow, the velocity and other relevant fields manifest complex spatial and temporal fluctuations. A video of steady turbulent flow from a tap will exhibit a constantly changing pattern and many length and time scales. In nature and technology, laminar flows are more the exception than the rule. Fluvial, oceanic, pyroclastic, atmospheric, and interstellar flows are generally turbulent, as are the flows of blood through the left ventricle and air in the lungs. Flows around land, sea, and air vehicles and through pipelines, heating, cooling, and ventilation systems are generally turbulent, as are most flows involved in industrial processing, combustion, chemical reactions, and crystal growth. Over the past year, a significant portion of our research activity has focused on numerical studies of Navier-Stokes-αβ model and extensions thereof. Our results regarding these and other approaches to turbulence modeling are described below.

  11. Computational Materials Science and Chemistry: Accelerating Discovery and Innovation through Simulation-Based Engineering and Science

    Energy Technology Data Exchange (ETDEWEB)

    Crabtree, George [Argonne National Lab. (ANL), Argonne, IL (United States); Glotzer, Sharon [University of Michigan; McCurdy, Bill [University of California Davis; Roberto, Jim [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2010-07-26

    This report is based on a SC Workshop on Computational Materials Science and Chemistry for Innovation on July 26-27, 2010, to assess the potential of state-of-the-art computer simulations to accelerate understanding and discovery in materials science and chemistry, with a focus on potential impacts in energy technologies and innovation. The urgent demand for new energy technologies has greatly exceeded the capabilities of today's materials and chemical processes. To convert sunlight to fuel, efficiently store energy, or enable a new generation of energy production and utilization technologies requires the development of new materials and processes of unprecedented functionality and performance. New materials and processes are critical pacing elements for progress in advanced energy systems and virtually all industrial technologies. Over the past two decades, the United States has developed and deployed the world's most powerful collection of tools for the synthesis, processing, characterization, and simulation and modeling of materials and chemical systems at the nanoscale, dimensions of a few atoms to a few hundred atoms across. These tools, which include world-leading x-ray and neutron sources, nanoscale science facilities, and high-performance computers, provide an unprecedented view of the atomic-scale structure and dynamics of materials and the molecular-scale basis of chemical processes. For the first time in history, we are able to synthesize, characterize, and model materials and chemical behavior at the length scale where this behavior is controlled. This ability is transformational for the discovery process and, as a result, confers a significant competitive advantage. Perhaps the most spectacular increase in capability has been demonstrated in high performance computing. Over the past decade, computational power has increased by a factor of a million due to advances in hardware and software. This rate of improvement, which shows no sign of

  12. Impact studies of five ceramic materials and pyrex

    International Nuclear Information System (INIS)

    Cunningham, B.J.; Holt, A.C.; Hord, B.L.; Kusubov, A.S.; Reaugh, J.E.; Wilkins, M.L.

    1998-01-01

    We measured the ballistic performance of five ceramic materials (alumina, silicon carbide, boron carbide, aluminum nitride, and titanium diboride) and Pyrex, when they are backed by thick steel plates. The projectile for all tests was a right-circular cylinder of tungsten sinter-alloy W2 with length 25.4 mm and diameter 6.35 mm, fired at velocities from 1.35 to 2.65 km/s. For this threat we determined the minimum areal density of each material that is needed to keep the projectile from penetrating the backup steel. For all of the facing materials studied here, this performance measure increases approximately linearly with projectile velocity. However, the rate of increase is significantly lower for aluminum nitride than for the other materials studied. Indeed, aluminum nitride is a poor performer at the lowest velocity tested, but is clearly the best at the highest velocity. Our computer simulations show the significant influence of the backing material on ceramic performance, manifested by a transition region extending two projectile diameters upstream from the material interface. Experiments with multiple material layers show that this influence also manifests itself through a significant dependence of ballistic performance on the ordering of the material

  13. Copyright and Computer Generated Materials – Is it Time to Reboot the Discussion About Authorship?

    Directory of Open Access Journals (Sweden)

    Anne Fitzgerald

    2013-12-01

    Full Text Available Computer generated materials are ubiquitous and we encounter them on a daily basis, even though most people are unaware that this is the case. Blockbuster movies, television weather reports and telephone directories all include material that is produced by utilising computer technologies. Copyright protection for materials generated by a programmed computer was considered by the Federal Court and Full Court of the Federal Court in Telstra Corporation Limited v Phone Directories Company Pty Ltd.  The court held that the White and Yellow pages telephone directories produced by Telstra and its subsidiary, Sensis, were not protected by copyright because they were computer-generated works which lacked the requisite human authorship.The Copyright Act 1968 (Cth does not contain specific provisions on the subsistence of copyright in computer-generated materials. Although the issue of copyright protection for computer-generated materials has been examined in Australia on two separate occasions by independently-constituted Copyright Law Review Committees over a period of 10 years (1988 to 1998, the Committees’ recommendations for legislative clarification by the enactment of specific amendments to the Copyright Act have not yet been implemented and the legal position remains unclear. In the light of the decision of the Full Federal Court in Telstra v Phone Directories it is timely to consider whether specific provisions should be enacted to clarify the position of computer-generated works under copyright law and, in particular, whether the requirement of human authorship for original works protected under Part III of the Copyright Act should now be reconceptualised to align with the realities of how copyright materials are created in the digital era.

  14. BEAM: A computational workflow system for managing and modeling material characterization data in HPC environments

    Energy Technology Data Exchange (ETDEWEB)

    Lingerfelt, Eric J [ORNL; Endeve, Eirik [ORNL; Ovchinnikov, Oleg S [ORNL; Borreguero Calvo, Jose M [ORNL; Park, Byung H [ORNL; Archibald, Richard K [ORNL; Symons, Christopher T [ORNL; Kalinin, Sergei V [ORNL; Messer, Bronson [ORNL; Shankar, Mallikarjun [ORNL; Jesse, Stephen [ORNL

    2016-01-01

    Improvements in scientific instrumentation allow imaging at mesoscopic to atomic length scales, many spectroscopic modes, and now with the rise of multimodal acquisition systems and the associated processing capability the era of multidimensional, informationally dense data sets has arrived. Technical issues in these combinatorial scientific fields are exacerbated by computational challenges best summarized as a necessity for drastic improvement in the capability to transfer, store, and analyze large volumes of data. The Bellerophon Environment for Analysis of Materials (BEAM) platform provides material scientists the capability to directly leverage the integrated computational and analytical power of High Performance Computing (HPC) to perform scalable data analysis and simulation via an intuitive, cross-platform client user interface. This framework delivers authenticated, push-button execution of complex user workflows that deploy data analysis algorithms and computational simulations utilizing the converged compute-and-data infrastructure at Oak Ridge National Laboratory s (ORNL) Compute and Data Environment for Science (CADES) and HPC environments like Titan at the Oak Ridge Leadership Computing Facility (OLCF). In this work we address the underlying HPC needs for characterization in the material science community, elaborate how BEAM s design and infrastructure tackle those needs, and present a small sub-set of user cases where scientists utilized BEAM across a broad range of analytical techniques and analysis modes.

  15. The Impact and Promise of Open-Source Computational Material for Physics Teaching

    Science.gov (United States)

    Christian, Wolfgang

    2017-01-01

    A computer-based modeling approach to teaching must be flexible because students and teachers have different skills and varying levels of preparation. Learning how to run the ``software du jour'' is not the objective for integrating computational physics material into the curriculum. Learning computational thinking, how to use computation and computer-based visualization to communicate ideas, how to design and build models, and how to use ready-to-run models to foster critical thinking is the objective. Our computational modeling approach to teaching is a research-proven pedagogy that predates computers. It attempts to enhance student achievement through the Modeling Cycle. This approach was pioneered by Robert Karplus and the SCIS Project in the 1960s and 70s and later extended by the Modeling Instruction Program led by Jane Jackson and David Hestenes at Arizona State University. This talk describes a no-cost open-source computational approach aligned with a Modeling Cycle pedagogy. Our tools, curricular material, and ready-to-run examples are freely available from the Open Source Physics Collection hosted on the AAPT-ComPADRE digital library. Examples will be presented.

  16. Application of Computer Simulation to Identify Erosion Resistance of Materials of Wet-steam Turbine Blades

    Science.gov (United States)

    Korostelyov, D. A.; Dergachyov, K. V.

    2017-10-01

    A problem of identifying the efficiency of using materials, coatings, linings and solderings of wet-steam turbine rotor blades by means of computer simulation is considered. Numerical experiments to define erosion resistance of materials of wet-steam turbine blades are described. Kinetic curves for erosion area and weight of the worn rotor blade material of turbines K-300-240 LMP and atomic icebreaker “Lenin” have been defined. The conclusion about the effectiveness of using different erosion-resistant materials and protection configuration of rotor blades is also made.

  17. Bibliography of Ethnic Heritage Studies Program Materials.

    Science.gov (United States)

    Kotler, Greta; And Others

    The Ethnic Heritage Studies Program was designed to teach students about the nature of their heritage and to study the contributions of the cultural heritage of other ethnic groups. This is a bibliography of materials developed by projects which received Federal Ethnic Heritage Studies Program grants during fiscal year 1974-75 and 1975-76.…

  18. Design Principles for the Atomic and Electronic Structure of Halide Perovskite Photovoltaic Materials: Insights from Computation.

    Science.gov (United States)

    Berger, Robert F

    2018-02-09

    In the current decade, perovskite solar cell research has emerged as a remarkably active, promising, and rapidly developing field. Alongside breakthroughs in synthesis and device engineering, halide perovskite photovoltaic materials have been the subject of predictive and explanatory computational work. In this Minireview, we focus on a subset of this computation: density functional theory (DFT)-based work highlighting the ways in which the electronic structure and band gap of this class of materials can be tuned via changes in atomic structure. We distill this body of computational literature into a set of underlying design principles for the band gap engineering of these materials, and rationalize these principles from the viewpoint of band-edge orbital character. We hope that this perspective provides guidance and insight toward the rational design and continued improvement of perovskite photovoltaics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. FOREWORD: Some thoughts about Jürgen Hafner's work in computational materials science Some thoughts about Jürgen Hafner's work in computational materials science

    Science.gov (United States)

    Heine, Volker

    2011-10-01

    groups extended these studies to molten [19] and quasicrystalline metals. The stunning result was that among the distorted structures there was a region where quasicrystals were stable with the lowest energy among all the structures they tried and which had shown up elsewhere [20]. In addition to Jürgen Hafner's actual research work published in over 600 research papers, including numerous review articles, several contributions to books and one monograph, he has done a great deal to establish our field of electronic structure calculation as the basis for understanding materials in Austria and across Europe. The founding and expansion of the Computational Materials Science Centre (CMS) in Vienna owes much to him, as well as the development of the European Psi-k network where he served as acting chairman in 1997-1999. He has been one of the leaders of the 'Surfaces and Catalysis Working Group' of Psi-k, and the instigator of several 'Theory Meets Industry' workshops [21] to stimulate the transfer of our methodology to industrial problems. Jürgen Hafner has always aimed for the highest intellectual standards. His nose for finding the most advanced work going on elsewhere has resulted in many international cooperations, including some in the USA and Japan. His list of international joint research projects runs to many pages. This in turn has been a major contributor to European cooperation, and in making it now the leading area in the world for our field. Hafner's research has always been linked closely to understanding puzzling experimental results, and in this way he has helped to establish a good reputation for computational physics within the mainstream of condensed matter physics of materials. It has taken quite a long time to establish computer simulations as a respectable component of research in condensed matter physics. "It is not real theory" people sneered from one side, and "computer simulations are not like real experiments" from the other. In the late 1990s a

  20. Ab Initio Molecular-Dynamics Simulation of Neuromorphic Computing in Phase-Change Memory Materials.

    Science.gov (United States)

    Skelton, Jonathan M; Loke, Desmond; Lee, Taehoon; Elliott, Stephen R

    2015-07-08

    We present an in silico study of the neuromorphic-computing behavior of the prototypical phase-change material, Ge2Sb2Te5, using ab initio molecular-dynamics simulations. Stepwise changes in structural order in response to temperature pulses of varying length and duration are observed, and a good reproduction of the spike-timing-dependent plasticity observed in nanoelectronic synapses is demonstrated. Short above-melting pulses lead to instantaneous loss of structural and chemical order, followed by delayed partial recovery upon structural relaxation. We also investigate the link between structural order and electrical and optical properties. These results pave the way toward a first-principles understanding of phase-change physics beyond binary switching.

  1. Interactive computer-based instruction: Basic material control and accounting demonstration

    International Nuclear Information System (INIS)

    Keisch, B.

    1993-01-01

    The use of interactive, computer-based training (CBT) courses can be a time- and resource-saving alternative to formal instruction in a classroom milieu. With CBT, students can proceed at their own pace, fit the study course into their schedule, and avoid the extra time and effort involved in travel and other special arrangements. The demonstration given here is an abbreviated, annotated version of a recently developed course in basic material control and accounting designed for the MC and A novice. The system used is ''Quest'' which includes multi-media capabilities, individual scoring, and built-in result-reporting capabilities for the course administrator. Efficient instruction and training are more important than ever because of the growing numbers of relatively inexperienced persons becoming active in safeguards

  2. Computer processing of dynamic scintigraphic studies

    International Nuclear Information System (INIS)

    Ullmann, V.

    1985-01-01

    The methods are discussed of the computer processing of dynamic scintigraphic studies which were developed, studied or implemented by the authors within research task no. 30-02-03 in nuclear medicine within the five year plan 1981 to 85. This was mainly the method of computer processing radionuclide angiography, phase radioventriculography, regional lung ventilation, dynamic sequential scintigraphy of kidneys and radionuclide uroflowmetry. The problems are discussed of the automatic definition of fields of interest, the methodology of absolute volumes of the heart chamber in radionuclide cardiology, the design and uses are described of the multipurpose dynamic phantom of heart activity for radionuclide angiocardiography and ventriculography developed within the said research task. All methods are documented with many figures showing typical clinical (normal and pathological) and phantom measurements. (V.U.)

  3. Advances in computational dynamics of particles, materials and structures a unified approach

    CERN Document Server

    Har, Jason

    2012-01-01

    Computational methods for the modeling and simulation of the dynamic response and behavior of particles, materials and structural systems have had a profound influence on science, engineering and technology. Complex science and engineering applications dealing with complicated structural geometries and materials that would be very difficult to treat using analytical methods have been successfully simulated using computational tools. With the incorporation of quantum, molecular and biological mechanics into new models, these methods are poised to play an even bigger role in the future. Ad

  4. Chemical analysis developments for fusion materials studies

    International Nuclear Information System (INIS)

    McCown, J.J.; Baldwin, D.L.; Keough, R.F.; Van der Cook, B.P.

    1985-04-01

    Several projects at Hanford under the management of the Westinghouse Hanford Company have involved research and development (R and D) on fusion materials. They include work on the Fusion Materials Irradiation Test Facility and its associated Experimental Lithium System; testing of irradiated lithium compounds as breeding materials; and testing of Li and Li-Pb alloy reactions with various atmospheres, concrete, and other reactor materials for fusion safety studies. In the course of these projects, a number of interesting and challenging analytical chemistry problems were encountered. They include sampling and analysis of lithium while adding and removing elements of interest; sampling, assaying and compound identification efforts on filters, aerosol particles and fire residues; development of dissolution and analysis techniques for measuring tritium and helium in lithium ceramics including oxides, aluminates, silicates and zirconates. An overview of the analytical chemistry development problems plus equipment and procedures used will be presented

  5. Computer processing of nuclear material data in the German Democratic Republic - as of August 1980

    International Nuclear Information System (INIS)

    Burmester, M.; Helming, M.

    1981-01-01

    A description is given of the computer-based processing of safeguards information within the frame of the State System of Accounting for and Control of Nuclear Material. Software includes the programmes ICR, PILMBR, LISTE, POL, DELE and SIP which produce the required reports to the IAEA on magnetic type and in the form of printouts, and provide a series of relevant information and data essentially facilitating the fulfilment of national obligations in the field of nuclear material control. (author)

  6. Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

    Science.gov (United States)

    Grujicic, M.; Arakere, G.; Pandurangan, B.; Ochterbeck, J. M.; Yen, C.-F.; Cheeseman, B. A.; Reynolds, A. P.; Sutton, M. A.

    2012-09-01

    Workpiece material flow and stirring/mixing during the friction stir welding (FSW) process are investigated computationally. Within the numerical model of the FSW process, the FSW tool is treated as a Lagrangian component while the workpiece material is treated as an Eulerian component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process was of a two-way thermo-mechanical character (i.e., frictional-sliding/plastic-work dissipation is taken to act as a heat source in the thermal-energy balance equation) while temperature is allowed to affect mechanical aspects of the model through temperature-dependent material properties. The workpiece material (AA5059, solid-solution strengthened and strain-hardened aluminum alloy) is represented using a modified version of the classical Johnson-Cook model (within which the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13 tool steel) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process parameters are investigated (e.g., weld pitch, tool tilt-angle, and the tool pin-size). The results pertaining to the material flow during FSW are compared with their experimental counterparts. It is found that, for the most part, experimentally observed material-flow characteristics are reproduced within the current FSW-process model.

  7. A computational study of the piezoelectric response due to the material effect in periodic, single island thin films and the geometric effect in periodic, bi-island thin films

    International Nuclear Information System (INIS)

    Liu, B.; Bhattacharyya, A.

    2010-01-01

    The electromechanical response of a square-periodic array of circular piezoelectric (PE) thin films alternating with non-piezoelectric (NPE) films is studied in this paper. The material effects are studied for four film/substrate combinations in absence of NPE films for which it is found that if d zxx zzz (z-axis being normal to the interfacial plane between the film and the substrate), it results in reduced substrate bending leading to reduced degradation in the electromechanical response of the thin film. The bi-island structure is studied for zinc oxide on strontium titanate, and, in general, it is seen that the NPE films not only reduce degradation of the electromechanical response of the PE films but also increase their internal stresses; the effect on the former is less than the latter. These effects are most prominent when the circular NPE thin films fill the space between the PE thin films and are elastically very stiff compared to the substrate.

  8. Highly efficient separation materials created by computational approach. For the separation of lanthanides and actinides

    International Nuclear Information System (INIS)

    Goto, Masahiro; Uezu, Kazuya; Aoshima, Atsushi; Koma, Yoshikazu

    2002-05-01

    In this study, efficient separation materials have been created by the computational approach. Based on the computational calculation, novel organophosphorus extractants, which have two functional moieties in the molecular structure, were developed for the recycle system of transuranium elements using liquid-liquid extraction. Furthermore, molecularly imprinted resins were prepared by the surface-imprint polymerization technique. Thorough this research project, we obtained two principal results: 1) design of novel extractants by computational approach, and 2) preparation of highly selective resins by the molecular imprinting technique. The synthesized extractants showed extremely high extractability to rare earth metals compared to those of commercially available extractants. The results of extraction equilibrium suggested that the structural effect of extractants is one of the key factors to enhance the selectivity and extractability in rare earth extractions. Furthermore, a computational analysis was carried out to evaluate the extraction properties for the extraction of rare earth metals by the synthesized extractants. The computer simulation was shown to be very useful for designing new extractants. The new concept to connect some functional moieties with a spacer is very useful and is a promising method to develop novel extractants for the treatment of nuclear fuel. In the second part, we proposed a novel molecular imprinting technique (surface template polymerization) for the separation of lanthanides and actinides. A surface-templated resin is prepared by an emulsion polymerization using an ion-binding (host) monomer, a resin matrix-forming monomer and the target Nd(III) metal ion. A host monomer which has amphiphilic nature forms a complex with a metal ion at the interface, and the complex remains as it is. After the matrix is polymerized, the coordination structure is 'imprinted' at the resin interface. Adsorption of Nd(III) and La(III) ions onto the

  9. Using Computational and Mechanical Models to Study Animal Locomotion

    Science.gov (United States)

    Miller, Laura A.; Goldman, Daniel I.; Hedrick, Tyson L.; Tytell, Eric D.; Wang, Z. Jane; Yen, Jeannette; Alben, Silas

    2012-01-01

    Recent advances in computational methods have made realistic large-scale simulations of animal locomotion possible. This has resulted in numerous mathematical and computational studies of animal movement through fluids and over substrates with the purpose of better understanding organisms’ performance and improving the design of vehicles moving through air and water and on land. This work has also motivated the development of improved numerical methods and modeling techniques for animal locomotion that is characterized by the interactions of fluids, substrates, and structures. Despite the large body of recent work in this area, the application of mathematical and numerical methods to improve our understanding of organisms in the context of their environment and physiology has remained relatively unexplored. Nature has evolved a wide variety of fascinating mechanisms of locomotion that exploit the properties of complex materials and fluids, but only recently are the mathematical, computational, and robotic tools available to rigorously compare the relative advantages and disadvantages of different methods of locomotion in variable environments. Similarly, advances in computational physiology have only recently allowed investigators to explore how changes at the molecular, cellular, and tissue levels might lead to changes in performance at the organismal level. In this article, we highlight recent examples of how computational, mathematical, and experimental tools can be combined to ultimately answer the questions posed in one of the grand challenges in organismal biology: “Integrating living and physical systems.” PMID:22988026

  10. Molecular modeling of protein materials: case study of elastin

    International Nuclear Information System (INIS)

    Tarakanova, Anna; Buehler, Markus J

    2013-01-01

    Molecular modeling of protein materials is a quickly growing area of research that has produced numerous contributions in fields ranging from structural engineering to medicine and biology. We review here the history and methods commonly employed in molecular modeling of protein materials, emphasizing the advantages for using modeling as a complement to experimental work. We then consider a case study of the protein elastin, a critically important ‘mechanical protein’ to exemplify the approach in an area where molecular modeling has made a significant impact. We outline the progression of computational modeling studies that have considerably enhanced our understanding of this important protein which endows elasticity and recoil to the tissues it is found in, including the skin, lungs, arteries and the heart. A vast collection of literature has been directed at studying the structure and function of this protein for over half a century, the first molecular dynamics study of elastin being reported in the 1980s. We review the pivotal computational works that have considerably enhanced our fundamental understanding of elastin's atomistic structure and its extraordinary qualities—focusing on two in particular: elastin's superb elasticity and the inverse temperature transition—the remarkable ability of elastin to take on a more structured conformation at higher temperatures, suggesting its effectiveness as a biomolecular switch. Our hope is to showcase these methods as both complementary and enriching to experimental approaches that have thus far dominated the study of most protein-based materials. (topical review)

  11. Electronic cleansing for computed tomography (CT) colonography using a scale-invariant three-material model

    NARCIS (Netherlands)

    Serlie, Iwo W. O.; Vos, Frans M.; Truyen, Roel; Post, Frits H.; Stoker, Jaap; van Vliet, Lucas J.

    2010-01-01

    A well-known reading pitfall in computed tomography (CT) colonography is posed by artifacts at T-junctions, i.e., locations where air-fluid levels interface with the colon wall. This paper presents a scale-invariant method to determine material fractions in voxels near such T-junctions. The proposed

  12. Experimental investigation of surface determination process on multi-material components for dimensional computed tomography

    DEFF Research Database (Denmark)

    Borges de Oliveira, Fabrício; Stolfi, Alessandro; Bartscher, Markus

    2016-01-01

    The possibility of measuring multi-material components, while assessing inner and outer features simultaneously makes X-ray computed tomography (CT) the latest evolution in the field of coordinate measurement systems (CMSs). However, the difficulty in selecting suitable scanning parameters and su...

  13. Computer Assisted Language Learning. Routledge Studies in Computer Assisted Language Learning

    Science.gov (United States)

    Pennington, Martha

    2011-01-01

    Computer-assisted language learning (CALL) is an approach to language teaching and learning in which computer technology is used as an aid to the presentation, reinforcement and assessment of material to be learned, usually including a substantial interactive element. This books provides an up-to date and comprehensive overview of…

  14. Computer based ultrasonic system for mechanical and acoustical characterization of materials

    International Nuclear Information System (INIS)

    Rosly Jaafar; Mohd Rozni Mohd Yusof; Khaidzir Hamzah; Md Supar Rohani; Rashdi Shah Ahmad; Amiruddin Shaari

    2001-01-01

    Propagation of both modes of ultrasonic waves velocity i.e. longitudinal (compressional) and transverse (shear), propagating in a material are closely linked with the material's physical and mechanical properties. By measuring both velocity modes, materials' properties such as Young's, bulk and shear moduli, compressibility, Poisson ratio and acoustic impedance can be determined. This paper describes the development of a system that is able to perform the above tasks and is known as Computer Based Ultrasonic for Mechanical and Acoustical Characterisation of Materials (UMC). The system was developed in the NDT Instrumentation and Signal Processing (NDTSP) laboratory of the Physics Department, Universiti Teknologi Malaysia. Measurements were made on four solid samples, namely, glass, copper, mild steel and aluminium. The results of measurements obtained were found to be in good agreement with the values of measurements made using standard methods. The main advantage of using this system over other methods is that single measurement of two ultrasonic velocity modes yields six material's properties. (Author)

  15. An Integrated Computational Materials Engineering Method for Woven Carbon Fiber Composites Preforming Process

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weizhao; Ren, Huaqing; Wang, Zequn; Liu, Wing K.; Chen, Wei; Zeng, Danielle; Su, Xuming; Cao, Jian

    2016-10-19

    An integrated computational materials engineering method is proposed in this paper for analyzing the design and preforming process of woven carbon fiber composites. The goal is to reduce the cost and time needed for the mass production of structural composites. It integrates the simulation methods from the micro-scale to the macro-scale to capture the behavior of the composite material in the preforming process. In this way, the time consuming and high cost physical experiments and prototypes in the development of the manufacturing process can be circumvented. This method contains three parts: the micro-scale representative volume element (RVE) simulation to characterize the material; the metamodeling algorithm to generate the constitutive equations; and the macro-scale preforming simulation to predict the behavior of the composite material during forming. The results show the potential of this approach as a guidance to the design of composite materials and its manufacturing process.

  16. Integrated Computational Materials Engineering (ICME) for Third Generation Advanced High-Strength Steel Development

    Energy Technology Data Exchange (ETDEWEB)

    Savic, Vesna; Hector, Louis G.; Ezzat, Hesham; Sachdev, Anil K.; Quinn, James; Krupitzer, Ronald; Sun, Xin

    2015-06-01

    This paper presents an overview of a four-year project focused on development of an integrated computational materials engineering (ICME) toolset for third generation advanced high-strength steels (3GAHSS). Following a brief look at ICME as an emerging discipline within the Materials Genome Initiative, technical tasks in the ICME project will be discussed. Specific aims of the individual tasks are multi-scale, microstructure-based material model development using state-of-the-art computational and experimental techniques, forming, toolset assembly, design optimization, integration and technical cost modeling. The integrated approach is initially illustrated using a 980 grade transformation induced plasticity (TRIP) steel, subject to a two-step quenching and partitioning (Q&P) heat treatment, as an example.

  17. The traveling salesman problem a computational study

    CERN Document Server

    Applegate, David L; Chvatal, Vasek; Cook, William J

    2006-01-01

    This book presents the latest findings on one of the most intensely investigated subjects in computational mathematics--the traveling salesman problem. It sounds simple enough: given a set of cities and the cost of travel between each pair of them, the problem challenges you to find the cheapest route by which to visit all the cities and return home to where you began. Though seemingly modest, this exercise has inspired studies by mathematicians, chemists, and physicists. Teachers use it in the classroom. It has practical applications in genetics, telecommunications, and neuroscience.

  18. On several computer-oriented studies

    International Nuclear Information System (INIS)

    Takahashi, Ryoichi

    1982-01-01

    To utilize fully digital techniques for solving various difficult problems, nuclear engineers have recourse to computer-oriented approaches. The current trend, in such fields as optimization theory, control system theory and computational fluid dynamics reflect the ability to use computers to obtain numerical solutions to complex problems. Special purpose computers will be used as the integral part of the solving system to process a large amount of data, to implement a control law and even to produce a decision-making. Many problem-solving systems designed in the future will incorporate special-purpose computers as system component. The optimum use of computer system is discussed: why are energy model, energy data base and a big computer used; why will the economic process-computer be allocated to nuclear plants in the future; why should the super-computer be demonstrated at once. (Mori, K.)

  19. Materials study for reacting plasma machine

    International Nuclear Information System (INIS)

    Kamada, Kohji; Hamada, Yasuji

    1982-01-01

    A new reacting plasma machine is designed, and will be constructed at the Institute of Plasma Physics, Nagoya University. It is important to avoid the activation of the materials for the machine, accordingly, aluminum alloy has been considered as the material since the induced activity of aluminum due to 14 MeV neutrons is small. The vacuum chamber of the new machine consists of four modules, and the remote control of each module is considered. However, the cost of the remote control of modules is expensive. To minimize the dependence on the remote control, the use of aluminum alloy is considered as the first step. The low electrical resistivity, over-ageing, weak mechanical strength and eddy current characteristics of aluminum alloy must be improved. The physical and electrical properties of various aluminum alloys have been investigated. Permeability of hydrogen through aluminum, the recycling characteristics and surface coating materials have been also studied. (Kato, T.)

  20. Whither the Material in New Media Studies?

    Directory of Open Access Journals (Sweden)

    John W. Kim

    2013-09-01

    Full Text Available This article addresses how new media theory has been founded on an endemic exclusion and erasure of a concept of the material, because of the ascendancy of a concept of the virtual in theoretical and historical research on the development of new media technologies. In order to develop this claim, three influential accounts of the virtual in media studies are reviewed (the history of technologies of the virtual, embodiment and informatics, and post-structuralist theories of digital media in order to demonstrate how each is grounded in an exclusion of the material. On the basis of this analysis, the article poses a definition of the material that responds to, but is not informed by, these exclusions, one that acknowledges the media’s role in enhancing one’s capacity to cognize the things in one’s immediate physical surroundings.

  1. Computed tomography study of otitis media

    International Nuclear Information System (INIS)

    Bahia, Paulo Roberto Valle; Marchiori, Edson

    1997-01-01

    The findings of computed tomography (CT) of 89 patients clinically suspected of having otitis media were studied in this work. Such results were compared to clinical diagnosis, otoscopy, surgical findings and previous data. Among the results of our analysis, we studied seven patients with acute otitis media and 83 patients with chronic otitis media. The patients with acute otitis media have undergone CT examinations to evaluate possible spread to central nervous system. The diagnosis of cholesteatoma, its extension and complications were the main indication. for chronic otitis media study. The main findings of the cholesteatomatous otitis were the occupation of the epitympanun, the bony wall destruction and the ossicular chain erosion. The CT demonstrated a great sensibility to diagnose the cholesteatoma. (author)

  2. The influence on the images of computed tomography caused by the use of artificial cranial reconstructive materials

    International Nuclear Information System (INIS)

    Itokawa, Hiroshi; Moriya, Masao; Fujimoto, Michio; Nagashima, Goro; Suzuki, Ryuta; Fujimoto, Tsukasa; Yasuda, Mitsuyoshi; Kato, Kyoichi; Hirade, Tsuneo

    2008-01-01

    Various materials have been used for cranioplasty; however these materials frequently produce artifacts that appear when examined with conventional radiography. Computed tomography (CT) in particular, detects high density artifacts near artificial bones, which is manipulated by increased noise, and limits diagnostic performance. The purpose of this study was to evaluate the extent and shape of the artifacts due to artificial cranial bones and to consider CT imaging parameters necessary for accurate recognition of structures under the materials. Four different artificial bone materials were evaluated in this study: hydroxyapatite with 40% or 50% porosity, titanium plate, and hydroxyapatite-polymethylmethacrylate composite (HA-PMMA). CT scanning was performed with standard clinical settings. Sample specimens were placed on the right side, under the artificial bones, and CT was performed to evaluate specimen visibility. We compared the artifacts created by the four bone types listed above, and measured the CT, values of those materials. With ordinary scan settings, all the artificial bones revealed high-density artifact surrounding the materials, including the inability to accurately measure specimen thickness. The upper part of the specimen in contact with the artificial bones could not be distinguished from the artifact. The CT value in the medial aspect of the artificial bones increased more than the actual CT values. Of the four artificial bone materials studied, HA-PMMA produced the fewest artifacts. Description of the structures under the artificial bones can be improved by extending the window width to aproximately twice that of normal settings. (author)

  3. Computational Methods for Nanoscale X-ray Computed Tomography Image Analysis of Fuel Cell and Battery Materials

    Science.gov (United States)

    Kumar, Arjun S.

    Over the last fifteen years, there has been a rapid growth in the use of high resolution X-ray computed tomography (HRXCT) imaging in material science applications. We use it at nanoscale resolutions up to 50 nm (nano-CT) for key research problems in large scale operation of polymer electrolyte membrane fuel cells (PEMFC) and lithium-ion (Li-ion) batteries in automotive applications. PEMFC are clean energy sources that electrochemically react with hydrogen gas to produce water and electricity. To reduce their costs, capturing their electrode nanostructure has become significant in modeling and optimizing their performance. For Li-ion batteries, a key challenge in increasing their scope for the automotive industry is Li metal dendrite growth. Li dendrites are structures of lithium with 100 nm features of interest that can grow chaotically within a battery and eventually lead to a short-circuit. HRXCT imaging is an effective diagnostics tool for such applications as it is a non-destructive method of capturing the 3D internal X-ray absorption coefficient of materials from a large series of 2D X-ray projections. Despite a recent push to use HRXCT for quantitative information on material samples, there is a relative dearth of computational tools in nano-CT image processing and analysis. Hence, we focus on developing computational methods for nano-CT image analysis of fuel cell and battery materials as required by the limitations in material samples and the imaging environment. The first problem we address is the segmentation of nano-CT Zernike phase contrast images. Nano-CT instruments are equipped with Zernike phase contrast optics to distinguish materials with a low difference in X-ray absorption coefficient by phase shifting the X-ray wave that is not diffracted by the sample. However, it creates image artifacts that hinder the use of traditional image segmentation techniques. To restore such images, we setup an inverse problem by modeling the X-ray phase contrast

  4. Advanced computational simulation for design and manufacturing of lightweight material components for automotive applications

    Energy Technology Data Exchange (ETDEWEB)

    Simunovic, S.; Aramayo, G.A.; Zacharia, T. [Oak Ridge National Lab., TN (United States); Toridis, T.G. [George Washington Univ., Washington, DC (United States); Bandak, F.; Ragland, C.L. [Dept. of Transportation, Washington, DC (United States)

    1997-04-01

    Computational vehicle models for the analysis of lightweight material performance in automobiles have been developed through collaboration between Oak Ridge National Laboratory, the National Highway Transportation Safety Administration, and George Washington University. The vehicle models have been verified against experimental data obtained from vehicle collisions. The crashed vehicles were analyzed, and the main impact energy dissipation mechanisms were identified and characterized. Important structural parts were extracted and digitized and directly compared with simulation results. High-performance computing played a key role in the model development because it allowed for rapid computational simulations and model modifications. The deformation of the computational model shows a very good agreement with the experiments. This report documents the modifications made to the computational model and relates them to the observations and findings on the test vehicle. Procedural guidelines are also provided that the authors believe need to be followed to create realistic models of passenger vehicles that could be used to evaluate the performance of lightweight materials in automotive structural components.

  5. Many Body Methods from Chemistry to Physics: Novel Computational Techniques for Materials-Specific Modelling: A Computational Materials Science and Chemistry Network

    Energy Technology Data Exchange (ETDEWEB)

    Millis, Andrew [Columbia Univ., New York, NY (United States). Dept. of Physics

    2016-11-17

    Understanding the behavior of interacting electrons in molecules and solids so that one can predict new superconductors, catalysts, light harvesters, energy and battery materials and optimize existing ones is the ``quantum many-body problem’’. This is one of the scientific grand challenges of the 21st century. A complete solution to the problem has been proven to be exponentially hard, meaning that straightforward numerical approaches fail. New insights and new methods are needed to provide accurate yet feasible approximate solutions. This CMSCN project brought together chemists and physicists to combine insights from the two disciplines to develop innovative new approaches. Outcomes included the Density Matrix Embedding method, a new, computationally inexpensive and extremely accurate approach that may enable first principles treatment of superconducting and magnetic properties of strongly correlated materials, new techniques for existing methods including an Adaptively Truncated Hilbert Space approach that will vastly expand the capabilities of the dynamical mean field method, a self-energy embedding theory and a new memory-function based approach to the calculations of the behavior of driven systems. The methods developed under this project are now being applied to improve our understanding of superconductivity, to calculate novel topological properties of materials and to characterize and improve the properties of nanoscale devices.

  6. Here and now: the intersection of computational science, quantum-mechanical simulations, and materials science

    Science.gov (United States)

    Marzari, Nicola

    The last 30 years have seen the steady and exhilarating development of powerful quantum-simulation engines for extended systems, dedicated to the solution of the Kohn-Sham equations of density-functional theory, often augmented by density-functional perturbation theory, many-body perturbation theory, time-dependent density-functional theory, dynamical mean-field theory, and quantum Monte Carlo. Their implementation on massively parallel architectures, now leveraging also GPUs and accelerators, has started a massive effort in the prediction from first principles of many or of complex materials properties, leading the way to the exascale through the combination of HPC (high-performance computing) and HTC (high-throughput computing). Challenges and opportunities abound: complementing hardware and software investments and design; developing the materials' informatics infrastructure needed to encode knowledge into complex protocols and workflows of calculations; managing and curating data; resisting the complacency that we have already reached the predictive accuracy needed for materials design, or a robust level of verification of the different quantum engines. In this talk I will provide an overview of these challenges, with the ultimate prize being the computational understanding, prediction, and design of properties and performance for novel or complex materials and devices.

  7. Computer-Aided Design of Materials for use under High Temperature Operating Condition

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopal, K. R.; Rao, I. J.

    2010-01-31

    The procedures in place for producing materials in order to optimize their performance with respect to creep characteristics, oxidation resistance, elevation of melting point, thermal and electrical conductivity and other thermal and electrical properties are essentially trial and error experimentation that tend to be tremendously time consuming and expensive. A computational approach has been developed that can replace the trial and error procedures in order that one can efficiently design and engineer materials based on the application in question can lead to enhanced performance of the material, significant decrease in costs and cut down the time necessary to produce such materials. The work has relevance to the design and manufacture of turbine blades operating at high operating temperature, development of armor and missiles heads; corrosion resistant tanks and containers, better conductors of electricity, and the numerous other applications that are envisaged for specially structured nanocrystalline solids. A robust thermodynamic framework is developed within which the computational approach is developed. The procedure takes into account microstructural features such as the dislocation density, lattice mismatch, stacking faults, volume fractions of inclusions, interfacial area, etc. A robust model for single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model is developed. Having developed the model, we then implement in a computational scheme using the software ABAQUS/STANDARD. The results of the simulation are compared against experimental data in realistic geometries.

  8. Dissociated dislocations in Ni: a computational study

    International Nuclear Information System (INIS)

    Szelestey, P.; Patriarca, M.; Kaski, K.

    2005-01-01

    A systematic computational study of the behavior of a (1/2) dissociated screw dislocation in fcc nickel is presented, in which atomic interactions are described through an embedded-atom potential. A suitable external stress is applied on the system, both for modifying the equilibrium separation distance d and moving the dislocation complex. The structure of the dislocation and its corresponding changes during the motion are studied in the framework of the two-dimensional Peierls model, for different values of the ratio d/a', where a' is the period of the Peierls potential. The distance between the edge and screw components of the partials, as well as their widths, undergo a modulation with period a', as the dislocation moves, and the amplitudes of such oscillations are shown to depend on d/a'. The stress profile acting on the dislocation complex is analyzed and the effective Peierls stress is estimated for different values of d/a'

  9. Radiation damage studies of nuclear structural materials

    International Nuclear Information System (INIS)

    Barat, P.

    2012-01-01

    Maximum utilization of fuel in nuclear reactors is one of the important aspects for operating them economically. The main hindrance to achieve this higher burnups of nuclear fuel for the nuclear reactors is the possibility of the failure of the metallic core components during their operation. Thus, the study of the cause of the possibility of failure of these metallic structural materials of nuclear reactors during full power operation due to radiation damage, suffered inside the reactor core, is an important field of studies bearing the basic to industrial scientific views.The variation of the microstructure of the metallic core components of the nuclear reactors due to radiation damage causes enormous variation in the structure and mechanical properties. A firm understanding of this variation of the mechanical properties with the variation of microstructure will serve as a guide for creating new, more radiation-tolerant materials. In our centre we have irradiated structural materials of Indian nuclear reactors by charged particles from accelerator to generate radiation damage and studied the some aspects of the variation of microstructure by X-ray diffraction studies. Results achieved in this regards, will be presented. (author)

  10. Preservation of adobe buildings. Study of materials

    Science.gov (United States)

    Velosa, A.; Rocha, F.; Costa, C.; Varum, H.

    2012-04-01

    Adobe buildings are common in the central region of Portugal due to the lack of natural stone in the surrounding area. This type of construction technique lasted until the 20th Century, at which time cementitious materials, with faster hardening and greater structural capacity substituted traditional materials and techniques. Currently, a significant percentage of these buildings is vacant and many are degraded and in need of conservation actions. Adobes from central Portugal are distinctive as they are lightly coloured and made from air lime and quarry sand. Although some adobes were manufactured locally, most were produced almost 'industrially' and sold to nearby regions. In order to preserve this heritage, conservation actions must be undertaken. So as to ensure the adequacy of these actions and compatibility between original materials and new ones, a thorough study of adobe compostion is mandatory. The current study is an initial step in the characterization of earth based construction materials from central Portugal. Adobe samples were collected from residential buildings in two different locations. The determination of the composition of adobe blocks encompassed the determination of the binder fraction and of their chemical composition and also the particle size analysis of the aggregate. For this purpose FRX analysis, acid dissolution and dry sieving were performed. Methylene blue test was also executed in order to determine the clay fraction. Additionally, the mineral composition of powder samples and oriented samples was performed using XRD analysis in order to determine the clay minerals present in the blocks. As adobe blocks are extremely prone to the action of water the Geelong test was undertaken in order to provide information in terms of durability. It was concluded that air lime was generally used in adobe compositions. However, the clay content varies in adobes from different regions, providing distinct durability characteristics to these materials.

  11. Computer program for prediction of the deposition of material released from fixed and rotary wing aircraft

    Science.gov (United States)

    Teske, M. E.

    1984-01-01

    This is a user manual for the computer code ""AGDISP'' (AGricultural DISPersal) which has been developed to predict the deposition of material released from fixed and rotary wing aircraft in a single-pass, computationally efficient manner. The formulation of the code is novel in that the mean particle trajectory and the variance about the mean resulting from turbulent fluid fluctuations are simultaneously predicted. The code presently includes the capability of assessing the influence of neutral atmospheric conditions, inviscid wake vortices, particle evaporation, plant canopy and terrain on the deposition pattern.

  12. Development studies of captopril certified reference material

    Directory of Open Access Journals (Sweden)

    Raquel Nogueira

    2011-06-01

    Full Text Available This paper describes the studies performed with the candidate Certified Reference Material (CRM of captopril, the first CRM of an active pharmaceutical ingredient (API in Brazil, including determination of impurities (organic, inorganic and volatiles, homogeneity testing, short- and long-term stability studies, calculation of captopril content using the mass balance approach, and estimation of the associated measurement uncertainty.Este artigo descreve os estudos realizados com o candidato a Material de Referência Certificado (MRC de captopril, primeiro MRC de fármacos no Brasil, incluindo a determinação de impurezas (orgânicas, inorgânicas e voláteis, testes de homogeneidade, testes de estabilidade de curta e longa duração, cálculo do teor de captopril por balanço de massa e estimativa da incerteza de medição associada ao valor certificado.

  13. Runaway-electron-materials interaction studies

    International Nuclear Information System (INIS)

    Bolt, H.; Miyahara, A.

    1990-03-01

    During the operation of magnetic fusion devices it has been frequently observed that runaway electrons can cause severe damage to plasma facing components. The energy of the runaway electrons could possibly reach several 100 MeV in a next generation device with an energy content in the plasma in the order of 100 MJ. In this study effects of high energy electron - materials interaction were determined by laboratory experiments using particle beam facilities, i.e. the Electron Linear Accelerator of the Institute of Scientific and Industrial Research of Osaka University and the 10 MW Neutral Beam Injection Test Stand of the National Institute for Fusion Science. The experiments and further analyses lead to a first assessment of the damage thresholds of plasma facing materials and components under runaway electron impact. It was found that metals (stainless steel, molybdenum, tungsten) showed grain growth, crack formation and/or melting already below the threshold for crack initiation on graphite (14-33 MJ/m 2 ). Strong erosion of carbon materials would occur above 100 MJ/m 2 . Damage to metal coolant channels can occur already below an energy deposition of 100 MJ/m 2 . The energy deposited in the metal coolant channels depends on the thickness of the plasma facing carbon material D, with the shielding efficiency S of carbon approximately as S∼D 1.15 . (author) 304 refs. 12 tabs. 59 figs

  14. The use of computational thermodynamics to predict properties of multicomponent materials for nuclear applications

    International Nuclear Information System (INIS)

    Sundman, B.; Gueneau, C.

    2013-01-01

    Computational Thermodynamics is based on physically realistic models to describe metallic and oxide crystalline phases as well as the liquid and gas in a consistent manner. The models are used to assess experimental and theoretical data for many different materials and several thermodynamic databases has been developed for steels, ceramics, semiconductor materials as well as materials for nuclear applications. Within CEA a long term work is ongoing to develop a database for the properties of nuclear fuels and structural materials. An overview of the modelling technique will be given and several examples of the application of the database to different problems, both for traditional phase diagram calculations and its use in simulating phase transformations. The following diagrams (Fig. 1, Fig. 2 and Fig.3) show calculations in the U-Pu-O system. (authors)

  15. Direct methods for limit and shakedown analysis of structures advanced computational algorithms and material modelling

    CERN Document Server

    Pisano, Aurora; Weichert, Dieter

    2015-01-01

    Articles in this book examine various materials and how to determine directly the limit state of a structure, in the sense of limit analysis and shakedown analysis. Apart from classical applications in mechanical and civil engineering contexts, the book reports on the emerging field of material design beyond the elastic limit, which has further industrial design and technological applications. Readers will discover that “Direct Methods” and the techniques presented here can in fact be used to numerically estimate the strength of structured materials such as composites or nano-materials, which represent fruitful fields of future applications.   Leading researchers outline the latest computational tools and optimization techniques and explore the possibility of obtaining information on the limit state of a structure whose post-elastic loading path and constitutive behavior are not well defined or well known. Readers will discover how Direct Methods allow rapid and direct access to requested information in...

  16. Heavy ion linear accelerator for radiation damage studies of materials

    Energy Technology Data Exchange (ETDEWEB)

    Kutsaev, Sergey V.; Mustapha, Brahim; Ostroumov, Peter N.; Nolen, Jerry; Barcikowski, Albert; Pellin, Michael; Yacout, Abdellatif

    2017-03-01

    A new eXtreme MATerial (XMAT) research facility is being proposed at Argonne National Laboratory to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. This facility combines a new heavy-ion accelerator with the existing high-energy X-ray analysis capability of the Argonne Advanced Photon Source. The heavy-ion accelerator and target complex will enable experimenters to emulate the environment of a nuclear reactor making possible the study of fission fragment damage in materials. Material scientists will be able to use the measured material parameters to validate computer simulation codes and extrapolate the response of the material in a nuclear reactor environment. Utilizing a new heavy-ion accelerator will provide the appropriate energies and intensities to study these effects with beam intensities which allow experiments to run over hours or days instead of years. The XMAT facility will use a CW heavy-ion accelerator capable of providing beams of any stable isotope with adjustable energy up to 1.2 MeV/u for U-238(50+) and 1.7 MeV for protons. This energy is crucial to the design since it well mimics fission fragments that provide the major portion of the damage in nuclear fuels. The energy also allows damage to be created far from the surface of the material allowing bulk radiation damage effects to be investigated. The XMAT ion linac includes an electron cyclotron resonance ion source, a normal-conducting radio-frequency quadrupole and four normal-conducting multi-gap quarter-wave resonators operating at 60.625 MHz. This paper presents the 3D multi-physics design and analysis of the accelerating structures and beam dynamics studies of the linac.

  17. Heavy ion linear accelerator for radiation damage studies of materials.

    Science.gov (United States)

    Kutsaev, Sergey V; Mustapha, Brahim; Ostroumov, Peter N; Nolen, Jerry; Barcikowski, Albert; Pellin, Michael; Yacout, Abdellatif

    2017-03-01

    A new eXtreme MATerial (XMAT) research facility is being proposed at Argonne National Laboratory to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. This facility combines a new heavy-ion accelerator with the existing high-energy X-ray analysis capability of the Argonne Advanced Photon Source. The heavy-ion accelerator and target complex will enable experimenters to emulate the environment of a nuclear reactor making possible the study of fission fragment damage in materials. Material scientists will be able to use the measured material parameters to validate computer simulation codes and extrapolate the response of the material in a nuclear reactor environment. Utilizing a new heavy-ion accelerator will provide the appropriate energies and intensities to study these effects with beam intensities which allow experiments to run over hours or days instead of years. The XMAT facility will use a CW heavy-ion accelerator capable of providing beams of any stable isotope with adjustable energy up to 1.2 MeV/u for 238 U 50+ and 1.7 MeV for protons. This energy is crucial to the design since it well mimics fission fragments that provide the major portion of the damage in nuclear fuels. The energy also allows damage to be created far from the surface of the material allowing bulk radiation damage effects to be investigated. The XMAT ion linac includes an electron cyclotron resonance ion source, a normal-conducting radio-frequency quadrupole and four normal-conducting multi-gap quarter-wave resonators operating at 60.625 MHz. This paper presents the 3D multi-physics design and analysis of the accelerating structures and beam dynamics studies of the linac.

  18. Formulation and computational aspects of plasticity and damage models with application to quasi-brittle materials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.; Schreyer, H.L. [New Mexico Engineering Research Institute, Albuquerque, NM (United States)

    1995-09-01

    The response of underground structures and transportation facilities under various external loadings and environments is critical for human safety as well as environmental protection. Since quasi-brittle materials such as concrete and rock are commonly used for underground construction, the constitutive modeling of these engineering materials, including post-limit behaviors, is one of the most important aspects in safety assessment. From experimental, theoretical, and computational points of view, this report considers the constitutive modeling of quasi-brittle materials in general and concentrates on concrete in particular. Based on the internal variable theory of thermodynamics, the general formulations of plasticity and damage models are given to simulate two distinct modes of microstructural changes, inelastic flow and degradation of material strength and stiffness, that identify the phenomenological nonlinear behaviors of quasi-brittle materials. The computational aspects of plasticity and damage models are explored with respect to their effects on structural analyses. Specific constitutive models are then developed in a systematic manner according to the degree of completeness. A comprehensive literature survey is made to provide the up-to-date information on prediction of structural failures, which can serve as a reference for future research.

  19. A finite element computer program for the calculation of the resonant frequencies of anisotropic materials

    International Nuclear Information System (INIS)

    Fleury, W.H.; Rosinger, H.E.; Ritchie, I.G.

    1975-09-01

    A set of computer programs for the calculation of the flexural and torsional resonant frequencies of rectangular section bars of materials of orthotropic or higher symmetry are described. The calculations are used in the experimental determination and verification of the elastic constants of anisotropic materials. The simple finite element technique employed separates the inertial and elastic properties of the beam element into station and field transfer matrices respectively. It includes the Timoshenko beam corrections for flexure and Lekhnitskii's theory for torsion-flexure coupling. The programs also calculate the vibration shapes and surface nodal contours or Chladni figures of the vibration modes. (author)

  20. Computed tomography study of Alzheimer's disease

    Energy Technology Data Exchange (ETDEWEB)

    Arai, H; Kobayashi, K; Ikeda, Y; Nagao, Y; Ogihara, R; Kosaka, K

    1983-01-01

    Computed tomography (CT) was used to study cerebral atrophy in 18 patients with clinically diagnosed Alzheimer's disease of presenile type and in 14 healthy age-matched subjects as controls. Using the computerized planimetric method, Subarachnoid Space Volume Index and Ventricle Volume Index were calculated as the measure of cortical atrophy and ventricular dilatation respectively. From the results the following conclusions were drawn: 1. The cerebral atrophy in Alzheimer patients could be attributable to the disease processes rather than to physiological aging of the brain. 2. The degree of atrophy increases in parallel with the progress of the clinical stage, and the cortical atrophy is already apparent at an early stage, whereas the ventricular dilatation becomes pronounced at later stages. 3. CT could be one of the most useful clinical tests available for the diagnosis of Alzheimer's disease.

  1. A computed tomography study of Alzheimer's disease

    International Nuclear Information System (INIS)

    Arai, H.; Kobayashi, K.; Juntendo Univ. School of Medicine, Tokyo; Ikeda, Y.; Nagao, Y.; Ogihara, R.; Kosaka, K.; Psychiatric Research Inst. of Tokyo

    1983-01-01

    Computed tomography (CT) was used to study cerebral atrophy in 18 patients with clinically diagnosed Alzheimer's disease of presenile type and in 14 healthy age-matched subjects as controls. Using the computerized planimetric method, Subarachnoid Space Volume Index and Ventricle Volume Index were calculated as the measure of cortical atrophy and ventricular dilatation respectively. From the results the following conclusions were drawn: 1. The cerebral atrophy in Alzheimer patients could be attributable to the disease processes rather than to physiological aging of the brain. 2. The degree of atrophy increases in parallel with the progress of the clinical stage, and the cortical atrophy is already apparent at an early stage, whereas the ventricular dilatation becomes pronounced at later stages. 3. CT could be one of the most useful clinical tests available for the diagnosis of Alzheimer's disease. (orig.) [de

  2. Non-Determinism: An Abstract Concept in Computer Science Studies

    Science.gov (United States)

    Armoni, Michal; Gal-Ezer, Judith

    2007-01-01

    Non-determinism is one of the most important, yet abstract, recurring concepts of Computer Science. It plays an important role in Computer Science areas such as formal language theory, computability theory, distributed computing, and operating systems. We conducted a series of studies on the perception of non-determinism. In the current research,…

  3. Materials by design: An experimental and computational investigation on the microanatomy arrangement of porous metallic glasses

    International Nuclear Information System (INIS)

    Sarac, Baran; Klusemann, Benjamin; Xiao, Tao; Bargmann, Swantje

    2014-01-01

    The correlation of a material’s structure with its properties is one of the important unresolved issues in materials science research. This paper discusses a novel experimental and computational approach by which the influence of the pores on the mechanical properties of bulk metallic glasses (BMGs) can be systematically and quantitatively analyzed. The experimental stage involves the fabrication of a template whose pore configurations are pre-determined by computer-aided design tools, and replication of the designed patterns with BMGs. Quasi-static mechanical characterization of these complex microstructures is conducted under uniaxial tension and in-plane compression. For the numerical simulations, a non-local gradient-enhanced continuum mechanical model is established, using thermodynamic principles and periodic boundary conditions. The combination of the experimental and numerical results has identified the importance of the pore configuration, overall porosity and diameter to the spacing ratio of the pores to attain optimized material properties

  4. Computer model for economic study of unbleached kraft paperboard production

    Science.gov (United States)

    Peter J. Ince

    1984-01-01

    Unbleached kraft paperboard is produced from wood fiber in an industrial papermaking process. A highly specific and detailed model of the process is presented. The model is also presented as a working computer program. A user of the computer program will provide data on physical parameters of the process and on prices of material inputs and outputs. The program is then...

  5. Quasiparticle Interference Studies of Quantum Materials.

    Science.gov (United States)

    Avraham, Nurit; Reiner, Jonathan; Kumar-Nayak, Abhay; Morali, Noam; Batabyal, Rajib; Yan, Binghai; Beidenkopf, Haim

    2018-06-03

    Exotic electronic states are realized in novel quantum materials. This field is revolutionized by the topological classification of materials. Such compounds necessarily host unique states on their boundaries. Scanning tunneling microscopy studies of these surface states have provided a wealth of spectroscopic characterization, with the successful cooperation of ab initio calculations. The method of quasiparticle interference imaging proves to be particularly useful for probing the dispersion relation of the surface bands. Herein, how a variety of additional fundamental electronic properties can be probed via this method is reviewed. It is demonstrated how quasiparticle interference measurements entail mesoscopic size quantization and the electronic phase coherence in semiconducting nanowires; helical spin protection and energy-momentum fluctuations in a topological insulator; and the structure of the Bloch wave function and the relative insusceptibility of topological electronic states to surface potential in a topological Weyl semimetal. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Prediction of detonation and JWL eos parameters of energetic materials using EXPLO5 computer code

    CSIR Research Space (South Africa)

    Peter, Xolani

    2016-09-01

    Full Text Available Ballistic Organization Cape Town, South Africa 27-29 September 2016 1 PREDICTION OF DETONATION AND JWL EOS PARAMETERS OF ENERGETIC MATERIALS USING EXPLO5 COMPUTER CODE X. Peter*, Z. Jiba, M. Olivier, I.M. Snyman, F.J. Mostert and T.J. Sono.... Nowadays many numerical methods and programs are being used for carrying out thermodynamic calculations of the detonation parameters of condensed explosives, for example a BKW Fortran (Mader, 1967), Ruby (Cowperthwaite and Zwisler, 1974) TIGER...

  7. Calculation of shipboard fire conditions for radioactive materials packages with the methods of computational fluid dynamics

    International Nuclear Information System (INIS)

    Koski, J.A.; Wix, S.D.; Cole, J.K.

    1997-09-01

    Shipboard fires both in the same ship hold and in an adjacent hold aboard a break-bulk cargo ship are simulated with a commercial finite-volume computational fluid mechanics code. The fire models and modeling techniques are described and discussed. Temperatures and heat fluxes to a simulated materials package are calculated and compared to experimental values. The overall accuracy of the calculations is assessed

  8. Raw material studies of West Central Serbia

    Directory of Open Access Journals (Sweden)

    Vera Bogosavljević Petrović

    2014-03-01

    Full Text Available This paper deals with raw material problems in the territory of West Central Serbia geologically determined as the Čačak-Kraljevo (or West Morava basin. Our research is presented through the most striking case studies, Lojanik, Vlaška Glava and Lazac.  The Lojanik hill is a silicified forest by origin. It has occasionally been in use from the earliest periods of prehistory until today as a source of black and ochre-coloured flint, opal and silicified wood. A detailed prospection, including the mapping of surface finds using square nets, was conducted during two research campaigns.The Vlaška Glava is an open-air Palaeolithic site at which artefacts made of white, ochre, red, brown and black chert, silicified magnesite, volcanic and metamorphic rocks were found. Our research of primary and secondary geological deposits in the vicinity of the site showed equivalent raw material. We also found an interesting primary deposit of high quality bluish grey flint with outcrop activities (Workshop 1.The Lazac shaft is a contemporary magnesite mine, recently abandoned because of the high percentage of silicon-dioxide. We determined the same raw material in collections found at nearby Neolithic sites. Certain similarities between the wooden support systems of ore exploration in the Middle Ages and modern times were established at the entrance of the shaft.Our research in the territory of the West Morava basin resulted in reconstruction of some links between geological deposits and settlements and also creation of a relevant base for future raw material studies.

  9. FINCRUSH : a computer program for impact analysis of radioactive material transport cask with fins

    International Nuclear Information System (INIS)

    Ikushima, Takeshi

    1997-05-01

    In drop impact analyses for radioactive material transport cask with cooling fins, relationship between fin plastic deformation and fin energy absorption is used. This relationship was obtained by ORNL experiments and MONSER Co. in Canada. Based on ORNL experiments, a computer program FINCRUSH has been developed for rapid safety analysis of cask drop impact to obtain the maximum impact acceleration and the maximum fin deformation. Main features of FINCRUSH are as follows: (1) annulus fins on a cylindrical shell and plate fins on a disk can be treated, (2) it is capable of graphical representations for calculation results and fin absorption energy data and (3) not only main frame computer but also work stations (OS UNIX) and personal computer (OS Windows) are available for use of the FINCRUSH. In the paper, brief illustration of calculation method of FINCRUSH is presented. The second section presents comparisons between FINCRUSH and experimental results. The third section provides a use's guide for FINCRUSH. (author)

  10. FINCRUSH : a computer program for impact analysis of radioactive material transport cask with fins

    Energy Technology Data Exchange (ETDEWEB)

    Ikushima, Takeshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-05-01

    In drop impact analyses for radioactive material transport cask with cooling fins, relationship between fin plastic deformation and fin energy absorption is used. This relationship was obtained by ORNL experiments and MONSER Co. in Canada. Based on ORNL experiments, a computer program FINCRUSH has been developed for rapid safety analysis of cask drop impact to obtain the maximum impact acceleration and the maximum fin deformation. Main features of FINCRUSH are as follows: (1) annulus fins on a cylindrical shell and plate fins on a disk can be treated, (2) it is capable of graphical representations for calculation results and fin absorption energy data and (3) not only main frame computer but also work stations (OS UNIX) and personal computer (OS Windows) are available for use of the FINCRUSH. In the paper, brief illustration of calculation method of FINCRUSH is presented. The second section presents comparisons between FINCRUSH and experimental results. The third section provides a use`s guide for FINCRUSH. (author)

  11. A hyperspectral X-ray computed tomography system for enhanced material identification

    Science.gov (United States)

    Wu, Xiaomei; Wang, Qian; Ma, Jinlei; Zhang, Wei; Li, Po; Fang, Zheng

    2017-08-01

    X-ray computed tomography (CT) can distinguish different materials according to their absorption characteristics. The hyperspectral X-ray CT (HXCT) system proposed in the present work reconstructs each voxel according to its X-ray absorption spectral characteristics. In contrast to a dual-energy or multi-energy CT system, HXCT employs cadmium telluride (CdTe) as the x-ray detector, which provides higher spectral resolution and separate spectral lines according to the material's photon-counter working principle. In this paper, a specimen containing ten different polymer materials randomly arranged was adopted for material identification by HXCT. The filtered back-projection algorithm was applied for image and spectral reconstruction. The first step was to sort the individual material components of the specimen according to their cross-sectional image intensity. The second step was to classify materials with similar intensities according to their reconstructed spectral characteristics. The results demonstrated the feasibility of the proposed material identification process and indicated that the proposed HXCT system has good prospects for a wide range of biomedical and industrial nondestructive testing applications.

  12. Degradation of metallic materials studied by correlative tomography

    Science.gov (United States)

    Burnett, T. L.; Holroyd, N. J. H.; Lewandowski, J. J.; Ogurreck, M.; Rau, C.; Kelley, R.; Pickering, E. J.; Daly, M.; Sherry, A. H.; Pawar, S.; Slater, T. J. A.; Withers, P. J.

    2017-07-01

    There are a huge array of characterization techniques available today and increasingly powerful computing resources allowing for the effective analysis and modelling of large datasets. However, each experimental and modelling tool only spans limited time and length scales. Correlative tomography can be thought of as the extension of correlative microscopy into three dimensions connecting different techniques, each providing different types of information, or covering different time or length scales. Here the focus is on the linking of time lapse X-ray computed tomography (CT) and serial section electron tomography using the focussed ion beam (FIB)-scanning electron microscope to study the degradation of metals. Correlative tomography can provide new levels of detail by delivering a multiscale 3D picture of key regions of interest. Specifically, the Xe+ Plasma FIB is used as an enabling tool for large-volume high-resolution serial sectioning of materials, and also as a tool for preparation of microscale test samples and samples for nanoscale X-ray CT imaging. The exemplars presented illustrate general aspects relating to correlative workflows, as well as to the time-lapse characterisation of metal microstructures during various failure mechanisms, including ductile fracture of steel and the corrosion of aluminium and magnesium alloys. Correlative tomography is already providing significant insights into materials behaviour, linking together information from different instruments across different scales. Multiscale and multifaceted work flows will become increasingly routine, providing a feed into multiscale materials models as well as illuminating other areas, particularly where hierarchical structures are of interest.

  13. [The Psychomat computer complex for psychophysiologic studies].

    Science.gov (United States)

    Matveev, E V; Nadezhdin, D S; Shemsudov, A I; Kalinin, A V

    1991-01-01

    The authors analyze the principles of the design of a computed psychophysiological system for universal uses. Show the effectiveness of the use of computed technology as a combination of universal computation and control potentialities of a personal computer equipped with problem-oriented specialized facilities of stimuli presentation and detection of the test subject's reactions. Define the hardware and software configuration of the microcomputer psychophysiological system "Psychomat". Describe its functional possibilities and the basic medico-technical characteristics. Review organizational issues of the maintenance of its full-scale production.

  14. Computer code to predict the heat of explosion of high energy materials

    International Nuclear Information System (INIS)

    Muthurajan, H.; Sivabalan, R.; Pon Saravanan, N.; Talawar, M.B.

    2009-01-01

    The computational approach to the thermochemical changes involved in the process of explosion of a high energy materials (HEMs) vis-a-vis its molecular structure aids a HEMs chemist/engineers to predict the important thermodynamic parameters such as heat of explosion of the HEMs. Such a computer-aided design will be useful in predicting the performance of a given HEM as well as in conceiving futuristic high energy molecules that have significant potential in the field of explosives and propellants. The software code viz., LOTUSES developed by authors predicts various characteristics of HEMs such as explosion products including balanced explosion reactions, density of HEMs, velocity of detonation, CJ pressure, etc. The new computational approach described in this paper allows the prediction of heat of explosion (ΔH e ) without any experimental data for different HEMs, which are comparable with experimental results reported in literature. The new algorithm which does not require any complex input parameter is incorporated in LOTUSES (version 1.5) and the results are presented in this paper. The linear regression analysis of all data point yields the correlation coefficient R 2 = 0.9721 with a linear equation y = 0.9262x + 101.45. The correlation coefficient value 0.9721 reveals that the computed values are in good agreement with experimental values and useful for rapid hazard assessment of energetic materials

  15. Theory, Modeling, Software and Hardware Development for Analytical and Computational Materials Science

    Science.gov (United States)

    Young, Gerald W.; Clemons, Curtis B.

    2004-01-01

    The focus of this Cooperative Agreement between the Computational Materials Laboratory (CML) of the Processing Science and Technology Branch of the NASA Glenn Research Center (GRC) and the Department of Theoretical and Applied Mathematics at The University of Akron was in the areas of system development of the CML workstation environment, modeling of microgravity and earth-based material processing systems, and joint activities in laboratory projects. These efforts complement each other as the majority of the modeling work involves numerical computations to support laboratory investigations. Coordination and interaction between the modelers, system analysts, and laboratory personnel are essential toward providing the most effective simulations and communication of the simulation results. Toward these means, The University of Akron personnel involved in the agreement worked at the Applied Mathematics Research Laboratory (AMRL) in the Department of Theoretical and Applied Mathematics while maintaining a close relationship with the personnel of the Computational Materials Laboratory at GRC. Network communication between both sites has been established. A summary of the projects we undertook during the time period 9/1/03 - 6/30/04 is included.

  16. A Computer Simulation to Assess the Nuclear Material Accountancy System of a MOX Fuel Fabrication Facility

    International Nuclear Information System (INIS)

    Portaix, C.G.; Binner, R.; John, H.

    2015-01-01

    SimMOX is a computer programme that simulates container histories as they pass through a MOX facility. It performs two parallel calculations: · the first quantifies the actual movements of material that might be expected to occur, given certain assumptions about, for instance, the accumulation of material and waste, and of their subsequent treatment; · the second quantifies the same movements on the basis of the operator's perception of the quantities involved; that is, they are based on assumptions about quantities contained in the containers. Separate skeletal Excel computer programmes are provided, which can be configured to generate further accountancy results based on these two parallel calculations. SimMOX is flexible in that it makes few assumptions about the order and operational performance of individual activities that might take place at each stage of the process. It is able to do this because its focus is on material flows, and not on the performance of individual processes. Similarly there are no pre-conceptions about the different types of containers that might be involved. At the macroscopic level, the simulation takes steady operation as its base case, i.e., the same quantity of material is deemed to enter and leave the simulated area, over any given period. Transient situations can then be superimposed onto this base scene, by simulating them as operational incidents. A general facility has been incorporated into SimMOX to enable the user to create an ''act of a play'' based on a number of operational incidents that have been built into the programme. By doing this a simulation can be constructed that predicts the way the facility would respond to any number of transient activities. This computer programme can help assess the nuclear material accountancy system of a MOX fuel fabrication facility; for instance the implications of applying NRTA (near real time accountancy). (author)

  17. Physicochemical studies of silicoaluminophosphate microporous materials

    International Nuclear Information System (INIS)

    Durrani, S.K.; Chughtai, N.A.; Akhtar, J.; Saeed, K.; Arif, M.; Moughal, M.J.; Ahmad, M.

    2000-01-01

    Crystalline microporous molecular sieve materials such as alumino phosphates (AlPO/sub 4/-n) and silicoaluminophosphates (SAPO-n) are gaining tremendous importance for petroleum refining and petrochemical industries due to its fascinating catalytic and ion exchange properties. Some selected silicoaluminophosphate crystalline microporous materials topologically related to the zeolites chabazite (SAPO-34), faujasite (SAPO-37) structure and to the novel structure Pentasil-types ( SAPO-5 and SAPO-11) have been synthesized hydrothermally at an autogenous pressure and different temperatures in PTFE-lined stainless steel digestion bomb. The physico-chemical characteristics of as-synthesized and calcined products were studied using different analytical techniques such as the differential thermal analysis (DTA), thermogravimetric (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and x-ray diffraction (XRD). Pore size was measured by the sorption of hydrocarbon molecules (n-hexane, neopentane). The surface area, porosity, particle size and particle size distribution were resolved using BET volumetric system and laser particle size analyzer. Crystallinity and unit cell parameters of these materials were also ascertained. (author)

  18. SIMS studies of low-K materials

    International Nuclear Information System (INIS)

    Lin Xuefeng; Smith, Stephen P.

    2006-01-01

    We report progress in conducting quantitative SIMS analyses of low-K materials. Electron-beam (e-beam) pre-irradiation of SIMS measurement sites was used to study the e-beam-induced effects on SIMS depth profiling of a porous organosilicate low-K material. Pre-irradiation of the sample surface using the e-beam causes a reduction in the thickness of the low-K film. SIMS profiling was used to sputter to identifiable marker positions within the pre-irradiated film. Physical measurement of the thickness of the remaining film was used to show that the e-beam-induced reduction in thickness occurs uniformly throughout the pre-irradiated film. Exposure of the film to the e-beam prior to SIMS analysis also resulted in minor changes in the composition of the film. However, pre-irradiation of the film is not part of the normal SIMS measurement procedure. We conclude that when the e-beam irradiation is used only for charge compensation during SIMS depth profiling, the SIMS analysis of the low-K material will not be significantly affected

  19. Optimization of coronary attenuation in coronary computed tomography angiography using diluted contrast material.

    Science.gov (United States)

    Kawaguchi, Naoto; Kurata, Akira; Kido, Teruhito; Nishiyama, Yoshiko; Kido, Tomoyuki; Miyagawa, Masao; Ogimoto, Akiyoshi; Mochizuki, Teruhito

    2014-01-01

    The purpose of this study was to evaluate a personalized protocol with diluted contrast material (CM) for coronary computed tomography angiography (CTA). One hundred patients with suspected coronary artery disease underwent retrospective electrocardiogram-gated coronary CTA on a 256-slice multidetector-row CT scanner. In the diluted CM protocol (n=50), the optimal scan timing and CM dilution rate were determined by the timing bolus scan, with 20% CM dilution (5ml/s during 10s) being considered suitable to achieve the target arterial attenuation of 350 Hounsfield units (HU). In the body weight (BW)-adjusted protocol (n=50, 222mg iodine/kg), only the optimal scan timing was determined by the timing bolus scan. The injection rate and volume in the timing bolus scan and real scan were identical between the 2 protocols. We compared the means and variations in coronary attenuation between the 2 protocols. Coronary attenuation (mean±SD) in the diluted CM and BW-adjusted protocols was 346.1±23.9 HU and 298.8±45.2 HU, respectively. The diluted CM protocol provided significantly higher coronary attenuation and lower variance than did the BW-adjusted protocol (P<0.05, in each). The diluted CM protocol facilitates more uniform attenuation on coronary CTA in comparison with the BW-adjusted protocol.  

  20. COMPUTING

    CERN Multimedia

    P. McBride

    The Computing Project is preparing for a busy year where the primary emphasis of the project moves towards steady operations. Following the very successful completion of Computing Software and Analysis challenge, CSA06, last fall, we have reorganized and established four groups in computing area: Commissioning, User Support, Facility/Infrastructure Operations and Data Operations. These groups work closely together with groups from the Offline Project in planning for data processing and operations. Monte Carlo production has continued since CSA06, with about 30M events produced each month to be used for HLT studies and physics validation. Monte Carlo production will continue throughout the year in the preparation of large samples for physics and detector studies ramping to 50 M events/month for CSA07. Commissioning of the full CMS computing system is a major goal for 2007. Site monitoring is an important commissioning component and work is ongoing to devise CMS specific tests to be included in Service Availa...

  1. Study for material analogs of FeSb2: Material design for thermoelectric materials

    Science.gov (United States)

    Kang, Chang-Jong; Kotliar, Gabriel

    2018-03-01

    Using the ab initio evolutionary algorithm (implemented in uspex) and electronic structure calculations we investigate the properties of a new thermoelectric material FeSbAs, which is a material analog of the enigmatic thermoelectric FeSb2. We utilize the density functional theory and the Gutzwiller method to check the energetics. We find that FeSbAs can be made thermodynamically stable above ˜30 GPa. We investigate the electronic structure and thermoelectric properties of FeSbAs based on the density functional theory and compare with those of FeSb2. Above 50 K, FeSbAs has higher Seebeck coefficients than FeSb2. Upon doping, the figure of merit becomes larger for FeSbAs than for FeSb2. Another material analog FeSbP, was also investigated, and found thermodynamically unstable even at very high pressure. Regarding FeSb2 as a member of a family of compounds (FeSb2, FeSbAs, and FeSbP) we elucidate what are the chemical handles that control the gaps in this series. We also investigate solubility (As or P for Sb in FeSb2) we found As to be more soluble. Finally, we study a two-band model for thermoelectric properties and find that the temperature dependent chemical potential and the presence of the ionized impurities are important to explain the extremum in the Seebeck coefficient exhibited in experiments for FeSb2.

  2. Effect of contrast material on image noise and radiation dose in adult chest computed tomography using automatic exposure control: A comparative study between 16-, 64- and 128-slice CT

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Jijo, E-mail: jijopaul1980@gmail.com [Clinic of the Goethe University, Department of Diagnostic and Interventional Radiology, Haus 23C UG, Theodor-Stern-Kai 7, 60590 Frankfurt am Main (Germany); Goethe University, Department of Biophysics, Max von Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Schell, Boris, E-mail: boris.schell@googlemail.com [Clinic of the Goethe University, Department of Diagnostic and Interventional Radiology, Haus 23C UG, Theodor-Stern-Kai 7, 60590 Frankfurt am Main (Germany); Kerl, J. Matthias, E-mail: matthias.kerl@gmai.com [Clinic of the Goethe University, Department of Diagnostic and Interventional Radiology, Haus 23C UG, Theodor-Stern-Kai 7, 60590 Frankfurt am Main (Germany); Maentele, Werner, E-mail: maentele@biophysik.uni-frankfurt.de [Goethe University, Department of Biophysics, Max von Laue-Strasse 1, 60438 Frankfurt am Main (Germany); Vogl, Thomas J., E-mail: t.vogl@em.uni-frankfurt.de [Clinic of the Goethe University, Department of Diagnostic and Interventional Radiology, Haus 23C UG, Theodor-Stern-Kai 7, 60590 Frankfurt am Main (Germany); Bauer, Ralf W., E-mail: ralfwbauer@aol.com [Clinic of the Goethe University, Department of Diagnostic and Interventional Radiology, Haus 23C UG, Theodor-Stern-Kai 7, 60590 Frankfurt am Main (Germany)

    2011-08-15

    Purpose: To determine the difference in radiation dose between non-enhanced (NECT) and contrast-enhanced (CECT) chest CT examinations contributed by contrast material with different scanner generations with automatic exposure control (AEC). Methods and materials: Each 42 adult patients received a NECT and CECT of the chest in one session on a 16-, 64- or 128-slice CT scanner with the same scan protocol settings. However, AEC technology (Care Dose 4D, Siemens) underwent upgrades in each of the three scanner generations. DLP, CTDIvol and image noise were compared. Results: Although absolute differences in image noise were very small and ranged between 10 and 13 HU for NECT and CECT in median, the differences in image noise and dose (DLP: 16-slice:+2.8%; 64-slice:+3.9%; 128-slice:+5.6%) between NECT and CECT were statistically significant in all groups. Image noise and dose parameters were significantly lower in the most recent 128-slice CT generation for both NECT and CECT (DLP: 16-slice:+35.5-39.2%; 64-slice:+6.8-8.5%). Conclusion: The presence of contrast material lead to an increase in dose for chest examinations in three CT generations with AEC. Although image noise values were significantly higher for CECT, the absolute differences were in a range of 3 HU. This can be regarded as negligible, thus indicating that AEC is able to fulfill its purpose of maintaining image quality. However, technological developments lead to a significant reduction of dose and image noise with the latest CT generation.

  3. Study guide to accompany computers data and processing

    CERN Document Server

    Deitel, Harvey M

    1985-01-01

    Study Guide to Accompany Computer and Data Processing provides information pertinent to the fundamental aspects of computers and computer technology. This book presents the key benefits of using computers.Organized into five parts encompassing 19 chapters, this book begins with an overview of the evolution of modern computing systems from the earliest mechanical calculating devices to microchips. This text then introduces computer hardware and describes the processor. Other chapters describe how microprocessors are made and describe the physical operation of computers. This book discusses as w

  4. Computational studies in tokamak equilibrium and transport

    International Nuclear Information System (INIS)

    Braams, B.J.

    1986-01-01

    This thesis is concerned with some problems arising in the magnetic confinement approach to controlled thermonuclear fusion. The work address the numerical modelling of equilibrium and transport properties of a confined plasma and the interpretation of experimental data. The thesis is divided in two parts. Part 1 is devoted to some aspects of the MHD equilibrium problem, both in the 'direct' formulation (given an equation for the plasma current, the corresponding equilibrium is to be determined) and in the 'inverse' formulation (the interpretation of measurements at the plasma edge). Part 2 is devoted to numerical studies of the edge plasma. The appropriate Navier-Stokes system of fluid equations is solved in a two-dimensional geometry. The main interest of this work is to develop an understanding of particle and energy transport in the scrape-off layer and onto material boundaries, and also to contribute to the conceptual design of the NET/INTOR tokamak reactor experiment. (Auth.)

  5. Computational Studies of Snake Venom Toxins.

    Science.gov (United States)

    Ojeda, Paola G; Ramírez, David; Alzate-Morales, Jans; Caballero, Julio; Kaas, Quentin; González, Wendy

    2017-12-22

    Most snake venom toxins are proteins, and participate to envenomation through a diverse array of bioactivities, such as bleeding, inflammation, and pain, cytotoxic, cardiotoxic or neurotoxic effects. The venom of a single snake species contains hundreds of toxins, and the venoms of the 725 species of venomous snakes represent a large pool of potentially bioactive proteins. Despite considerable discovery efforts, most of the snake venom toxins are still uncharacterized. Modern bioinformatics tools have been recently developed to mine snake venoms, helping focus experimental research on the most potentially interesting toxins. Some computational techniques predict toxin molecular targets, and the binding mode to these targets. This review gives an overview of current knowledge on the ~2200 sequences, and more than 400 three-dimensional structures of snake toxins deposited in public repositories, as well as of molecular modeling studies of the interaction between these toxins and their molecular targets. We also describe how modern bioinformatics have been used to study the snake venom protein phospholipase A2, the small basic myotoxin Crotamine, and the three-finger peptide Mambalgin.

  6. Computational Studies of Snake Venom Toxins

    Directory of Open Access Journals (Sweden)

    Paola G. Ojeda

    2017-12-01

    Full Text Available Most snake venom toxins are proteins, and participate to envenomation through a diverse array of bioactivities, such as bleeding, inflammation, and pain, cytotoxic, cardiotoxic or neurotoxic effects. The venom of a single snake species contains hundreds of toxins, and the venoms of the 725 species of venomous snakes represent a large pool of potentially bioactive proteins. Despite considerable discovery efforts, most of the snake venom toxins are still uncharacterized. Modern bioinformatics tools have been recently developed to mine snake venoms, helping focus experimental research on the most potentially interesting toxins. Some computational techniques predict toxin molecular targets, and the binding mode to these targets. This review gives an overview of current knowledge on the ~2200 sequences, and more than 400 three-dimensional structures of snake toxins deposited in public repositories, as well as of molecular modeling studies of the interaction between these toxins and their molecular targets. We also describe how modern bioinformatics have been used to study the snake venom protein phospholipase A2, the small basic myotoxin Crotamine, and the three-finger peptide Mambalgin.

  7. Real sequential evaluation of materials balance data with the computer program PROSA

    International Nuclear Information System (INIS)

    Bicking, U.; Golly, W.; Seifert, R.

    1991-01-01

    Material accountancy is an important tool for international nuclear safeguards. The aim is to detect a possible loss of material timely and with high probability. In this context, a computer program called PROSA (Program for Sequential Analysis of NRTA data) was developed at the Karlsruhe Nuclear Research Center. PROSA is a statistical tool to decide on the basis of statistical considerations whether or not in a given sequence of material balances a loss of material might have occurred. The evaluation of the material balance data (MUF values) is carried out with statistical test procedures. In the present PROSA version 4.0 three tests, Page's test, CUMUF test and GEMUF test are applied at a time. These three test procedures are the result of several years of research and are supposed to be the most promising ones with respect to the detection probability of possible losses of material as well as to the timeliness of such a detection. PROSA version 4.0 is a user-friendly, menudriven computer program which is suitable for routine field application. Data input - that means MUF values and measurement model - can be performed either by diskette or by key-enter. The output consists of an information whether or not an alarm is indicated. This information can be displayed either numerically or graphically. Therefore, a comfortable graphical output utility is attached to PROSA version 4.0. In this presentation the theoretical concepts implemented in PROSA will be explained. Furthermore, the functioning of the program will be presented and the performance of PROSA will be demonstrated using balance data of a real reprocessing campaign. (J.P.N.)

  8. Computing effective properties of random heterogeneous materials on heterogeneous parallel processors

    Science.gov (United States)

    Leidi, Tiziano; Scocchi, Giulio; Grossi, Loris; Pusterla, Simone; D'Angelo, Claudio; Thiran, Jean-Philippe; Ortona, Alberto

    2012-11-01

    In recent decades, finite element (FE) techniques have been extensively used for predicting effective properties of random heterogeneous materials. In the case of very complex microstructures, the choice of numerical methods for the solution of this problem can offer some advantages over classical analytical approaches, and it allows the use of digital images obtained from real material samples (e.g., using computed tomography). On the other hand, having a large number of elements is often necessary for properly describing complex microstructures, ultimately leading to extremely time-consuming computations and high memory requirements. With the final objective of reducing these limitations, we improved an existing freely available FE code for the computation of effective conductivity (electrical and thermal) of microstructure digital models. To allow execution on hardware combining multi-core CPUs and a GPU, we first translated the original algorithm from Fortran to C, and we subdivided it into software components. Then, we enhanced the C version of the algorithm for parallel processing with heterogeneous processors. With the goal of maximizing the obtained performances and limiting resource consumption, we utilized a software architecture based on stream processing, event-driven scheduling, and dynamic load balancing. The parallel processing version of the algorithm has been validated using a simple microstructure consisting of a single sphere located at the centre of a cubic box, yielding consistent results. Finally, the code was used for the calculation of the effective thermal conductivity of a digital model of a real sample (a ceramic foam obtained using X-ray computed tomography). On a computer equipped with dual hexa-core Intel Xeon X5670 processors and an NVIDIA Tesla C2050, the parallel application version features near to linear speed-up progression when using only the CPU cores. It executes more than 20 times faster when additionally using the GPU.

  9. Determination of tissue equivalent materials of a physical 8-year-old phantom for use in computed tomography

    International Nuclear Information System (INIS)

    Akhlaghi, Parisa; Miri Hakimabad, Hashem; Rafat Motavalli, Laleh

    2015-01-01

    This paper reports on the methodology applied to select suitable tissue equivalent materials of an 8-year phantom for use in computed tomography (CT) examinations. To find the appropriate tissue substitutes, first physical properties (physical density, electronic density, effective atomic number, mass attenuation coefficient and CT number) of different materials were studied. Results showed that, the physical properties of water and polyurethane (as soft tissue), B-100 and polyvinyl chloride (PVC) (as bone) and polyurethane foam (as lung) agree more with those of original tissues. Then in the next step, the absorbed doses in the location of 25 thermoluminescent dosimeters (TLDs) as well as dose distribution in one slice of phantom were calculated for original and these proposed materials by Monte Carlo simulation at different tube voltages. The comparisons suggested that at tube voltages of 80 and 100 kVp using B-100 as bone, water as soft tissue and polyurethane foam as lung is suitable for dosimetric study in pediatric CT examinations. In addition, it was concluded that by considering just the mass attenuation coefficient of different materials, the appropriate tissue equivalent substitutes in each desired X-ray energy range could be found. - Highlights: • A methodology to select tissue equivalent materials for use in CT was proposed. • Physical properties of different materials were studied. • TLDs dose and dose distribution were calculated for original and proposed materials. • B-100 as bone, and water as soft tissue are best substitute materials at 80 kVp. • Mass attenuation coefficient is determinant for selecting best tissue substitutes

  10. Study of material science by neutron scattering

    International Nuclear Information System (INIS)

    Kim, H.J.; Yoon, B.K.; Cheon, B.C.; Lee, C.Y.; Kim, C.S.

    1980-01-01

    To develop accurate methods of texture measurement in metallic materials by neutron diffraction, (100),(200),(111) and (310) pole figures have been measured for the oriented silicon steel sheet, and currently study of correction methods for neutron absorption and extinction effects are in progress. For quantitative analysis of texture of polycrystalline material with a cubic structure, a software has been developed to calculate inverse pole figures for arbitrary direction specified in the speciman as well as pole figures for arbitrary chosen crystallographic planes from three experimental pole figures. This work is to be extended for the calculation of three dimensional orientation distribution function and for the evaluation of errors in the quantitative analysis of texture. Work is also for the study of N-H...O hydrogen bond in amino acid by observing molecular motions using neutron inelastic scattering. Measurement of neutron inelastic scattering spectrum of L-Serine is completed at 100 0 K and over the energy transfer range of 20-150 meV. (KAERI INIS Section)

  11. Experimental fretting-wear studies of steam generator materials

    International Nuclear Information System (INIS)

    Fisher, N.J.; Chow, A.B.; Weckwerth, M.K.

    1994-01-01

    Flow-induced vibration of steam generator tubes results in fretting-wear damage due to impacting and rubbing of the tubes against their supports. This damage can be predicted by computing tube response to flow-induced excitation forces using analytical techniques, and then relating this response to resultant wear damage using experimentally-derived wear coefficients. Fretting-wear of steam generator materials has been studied experimentally at Chalk River Laboratories for two decades. Tests are conducted in machines that simulate steam generator environmental conditions and tube-to-support dynamic interactions. Different tube and support materials, tube-to-support clearances and tube support geometries have been studied. As well, the effect of environmental conditions, such as temperature, oxygen content, pH and chemistry control additive, have been investigated. Early studies showed that damage was related to contact force as long as other parameters, such as geometry and motion were held constant. Later studies have shown that damage is related to a parameter called work-rate, which combines both contact force and sliding distance. Results of short- and long-term fretting-wear tests for CANDU steam generator materials at realistic environmental conditions are presented. These results demonstrate that work-rate is appropriate correlating parameter for impact-sliding interaction

  12. Computed tomographic study of aged schizophrenic patients

    International Nuclear Information System (INIS)

    Seno, Haruo; Fujimoto, Akihiko; Ishino, Hiroshi; Shibata, Masahiro; Kuroda, Hiroyuki; Kanno, Hiroshi.

    1997-01-01

    The width of interhemispheric fissure, lateral ventricles and third ventricle were measured using cranial computed tomography (CT; linear method) in 45 elderly inpatients with chronic schizophrenia and in 28 age-matched control subjects. Twenty-three patients were men and 22 were women. In addition, Mini-Mental State Examination, Brief Psychiatric Rating Scale (BPRS) and a subclass of BPRS were undertaken in all patients. There is a significant enlargement of the maximum width of the interhemispheric fissure (in both male and female) and a significant enlargement of ventricular system (more severe in men than in women) in aged schizophrenics, as seen with CT, compared with normal controls. These findings are consistent with previous studies of non-aged schizophrenic patients. Based upon the relation between psychiatric symptoms and CT findings, the most striking is a significant negative correlation between the third ventricle enlargement and the positive and depressive symptoms in all patients. This result suggests that the advanced third ventricle enlargement may decrease these symptoms in aged schizophrenics. (author)

  13. Computed tomographic study on Mycoplasma pneumoniae pneumonia

    International Nuclear Information System (INIS)

    Tanaka, Hiroshi; Koba, Hiroyuki; Mori, Takuji; Mori, Masaki; Tsunematsu, Kazunori; Natori, Hiroshi; Asakawa, Mitsuo; Suzuki, Akira; Doi, Mikio.

    1985-01-01

    Serologically proven 21 patients with Mycoplasma pneumoniae pneumonia that showed infiltrative shadows on chest radiograms were studied by computed tomography (CT). Localization of the lesion and the fashion of its progression through the lung were analyzed. Following 3 loci were defined on the basis of the investigations of critical analysis of the chest radiograms, and of radiopathological analysis of the experimental animal model of mycoplasmal pneumonia with soft X-ray image. I: Peribronchial and periarterial interstitium. II: Bronchiole and its surroundings. III: Lung parenchyma, on hilar area as IIIh, on marginal area as IIIm. Even in the early phase of this disease, radiopathological findings on CT have been distributed in all loci mentioned above. The Shadow disappeared from locus III approximately 14th day from the onset. The shadow have remained, however, loci I, II for a long period. Those findings suggest that locus I and II are one of the major focus of Mycoplasma neumoniae pneumonia. Volume loss in the locus III was observed 78 % of the cases at 28th day from the onset. The shadow on locus IIIh was more prominent than locus IIIm. Reported analytical method with CT could be widely applied to disclose a radiopathological details in other infectious diseases of the lung. (author)

  14. Computational Studies of Protein Hydration Methods

    Science.gov (United States)

    Morozenko, Aleksandr

    It is widely appreciated that water plays a vital role in proteins' functions. The long-range proton transfer inside proteins is usually carried out by the Grotthuss mechanism and requires a chain of hydrogen bonds that is composed of internal water molecules and amino acid residues of the protein. In other cases, water molecules can facilitate the enzymes catalytic reactions by becoming a temporary proton donor/acceptor. Yet a reliable way of predicting water protein interior is still not available to the biophysics community. This thesis presents computational studies that have been performed to gain insights into the problems of fast and accurate prediction of potential water sites inside internal cavities of protein. Specifically, we focus on the task of attainment of correspondence between results obtained from computational experiments and experimental data available from X-ray structures. An overview of existing methods of predicting water molecules in the interior of a protein along with a discussion of the trustworthiness of these predictions is a second major subject of this thesis. A description of differences of water molecules in various media, particularly, gas, liquid and protein interior, and theoretical aspects of designing an adequate model of water for the protein environment are widely discussed in chapters 3 and 4. In chapter 5, we discuss recently developed methods of placement of water molecules into internal cavities of a protein. We propose a new methodology based on the principle of docking water molecules to a protein body which allows to achieve a higher degree of matching experimental data reported in protein crystal structures than other techniques available in the world of biophysical software. The new methodology is tested on a set of high-resolution crystal structures of oligopeptide-binding protein (OppA) containing a large number of resolved internal water molecules and applied to bovine heart cytochrome c oxidase in the fully

  15. Computational assessment of promising mid-infrared nonlinear optical materials Mg–IV–V2 (IV = Si, Ge, Sn; V = P, As): a first-principles study

    Science.gov (United States)

    Xiao, Jianping; Zhu, Shifu; Zhao, Beijun; Chen, Baojun; Liu, Hui; He, Zhiyu

    2018-03-01

    The mid-infrared (mid-IR) nonlinear optical (NLO) capabilities of Mg–IV–V2 (IV = Si, Ge, Sn; V = P, As) are systematically assessed by the first-principles calculation. The results show that the compounds in this group except MgSiP2 and MgSnP2 have moderate birefringence values to fulfill the phase-matching conditions. In particular, MgGeP2 and MgSiAs2 possess relatively large band gaps and almost three to four times larger static SHG coefficients than the benchmark material AgGaSe2, exhibiting good potential for mid-IR NLO application. According to the detailed analysis of the electronic structures, it is found that the dominant SHG contributions are from the orbitals of the asymmetry anionic unit [IV–V2]2‑. Moreover, the further evaluation reveals that MgSiAs2, MgGeAs2, MgSnP2 and MgSnAs2 are not thermodynamically stable and the new synthesis strategy (i.e. synthesis under non-equilibrium conditions) should be considered.

  16. Polychromatic Iterative Statistical Material Image Reconstruction for Photon-Counting Computed Tomography

    Directory of Open Access Journals (Sweden)

    Thomas Weidinger

    2016-01-01

    Full Text Available This work proposes a dedicated statistical algorithm to perform a direct reconstruction of material-decomposed images from data acquired with photon-counting detectors (PCDs in computed tomography. It is based on local approximations (surrogates of the negative logarithmic Poisson probability function. Exploiting the convexity of this function allows for parallel updates of all image pixels. Parallel updates can compensate for the rather slow convergence that is intrinsic to statistical algorithms. We investigate the accuracy of the algorithm for ideal photon-counting detectors. Complementarily, we apply the algorithm to simulation data of a realistic PCD with its spectral resolution limited by K-escape, charge sharing, and pulse-pileup. For data from both an ideal and realistic PCD, the proposed algorithm is able to correct beam-hardening artifacts and quantitatively determine the material fractions of the chosen basis materials. Via regularization we were able to achieve a reduction of image noise for the realistic PCD that is up to 90% lower compared to material images form a linear, image-based material decomposition using FBP images. Additionally, we find a dependence of the algorithms convergence speed on the threshold selection within the PCD.

  17. The Trope Tank: A Laboratory with Material Resources for Creative Computing

    Directory of Open Access Journals (Sweden)

    Nick Montfort

    2014-12-01

    Full Text Available http://dx.doi.org/10.5007/1807-9288.2014v10n2p53 Principles for organizing and making use of a laboratory with material computing resources are articulated. This laboratory, the Trope Tank, is a facility for teaching, research, and creative collaboration and offers hardware (in working condition and set up for use from the 1970s, 1980s, and 1990s, including videogame systems, home computers, and an arcade cabinet. To aid in investigating the material history of texts, the lab has a small 19th century letterpress, a typewriter, a print terminal, and dot-matrix printers. Other resources include controllers, peripherals, manuals, books, and software on physical media. These resources are used for teaching, loaned for local exhibitions and presentations, and accessed by researchers and artists. The space is primarily a laboratory (rather than a library, studio, or museum, so materials are organized by platform and intended use. Textual information about the historical contexts of the available systems, and resources are set up to allow easy operation, and even casual use, by researchers, teachers, students, and artists.

  18. Fluorescent X-ray computed tomography using synchrotron radiation for imaging nonradioactive tracer materials

    Energy Technology Data Exchange (ETDEWEB)

    Akiba, Masahiro; Yuasa, Tetsuya; Uchida, Akira; Akatsuka, Takao [Yamagata Univ., Yonezawa (Japan). Electrical and Information of Engineering; Takeda, Tohoru; Hyodo, Kazuyuki; Itai, Yuji

    1997-09-01

    We describe a system of fluorescent X-ray computed tomography using synchrotron radiation (SR-FXCT) to image nonradioactive contrast materials. The system operates on the basis of computed tomography (CT) scanned by the pencil beam. In the previous experiment, we have imaged an acrylic cylindrical phantom with cross-shaped channel, filled with a diluted iodine-based tracer material of 200 {mu}g/ml. This research is aimed to improve image quality, to select the optimum energy of the incident X-ray, to confirm quantitative evaluation of the image, and to demonstrate FXCT image for living body. First, we simulated output energy profile by the Monte Carlo simulation and confirmed to predetermine the incident X-ray energy at 37 keV, in order to separate the fluorescent photons from background scattering components. Next, the imaging experiment was performed by using conventional CT algorithm under the optimum parameter at the Tristan Accumulation Ring, KEK, Japan. An acrylic phantom containing five paraxial channels of 5 and 4 mm in diameter, could be imaged; where each channel was respectively filled with diluted iodine-based contrast materials of 50, 100, 200 and 500 {mu}g/ml. From the reconstructed image, we confirmed quantitativity in the FXCT image. Finally, a rat`s brain was imaged in vitro by FXCT and monochromatic transmission CT. The comparison between these results showed that the iodine-rich region in the FXCT image corresponded with that in the monochromatic transmission CT image. (author)

  19. MATERIALS COMPATIBILITY STUDY FOR THREE-DIMENSIONAL PRINTER MATERIALS

    Science.gov (United States)

    2017-09-01

    shown that the nanoparticle vapor emitted by a 3D printer can present both environmental and health concerns. A study by the Built Environment...because of the different retention times and spectral features (Figures 10–13). In addition , azacyclotrodecan-2-one (62% confidence level for...to separate the PEG from the rest of the compounds to enhance the ionization. It is possible that in addition to applying a column, other types of

  20. A study on a nano-scale materials simulation using a PC cluster

    International Nuclear Information System (INIS)

    Choi, Deok Kee; Ryu, Han Kyu

    2002-01-01

    Not a few scientists have paid attention to application of molecular dynamics to chemistry, biology and physics. With recent popularity of nano technology, nano-scale analysis has become a major subject in various engineering fields. A underlying nano scale analysis is based on classical molecular theories representing molecular dynamics. Based on Newton's law of motions of particles, the movement of each particles is to be determined by numerical integrations. As the size of computation is closely related with the number of molecules, materials simulation takes up huge amount of computer resources so that it is not until recent days that the application of molecular dynamics to materials simulations draw some attention from many researchers. Thanks to high-performance computers, materials simulation via molecular dynamics looks promising. In this study, a PC cluster consisting of multiple commodity PCs is established and nano scale materials simulations are carried out. Micro-sized crack propagation inside a nano material is displayed by the simulation

  1. Positron annihilation spectroscopy in materials structure studies

    International Nuclear Information System (INIS)

    Grafutin, Viktor I; Prokop'ev, Evgenii P

    2002-01-01

    A relatively new method of materials structure analysis - positron annihilation spectroscopy (PAS) - is reviewed. Measurements of positron lifetimes, the determination of positron 3γ- and 2γ-annihilation probabilities, and an investigation of the effects of different external factors on the fundamental characteristics of annihilation constitute the basis for this promising method. The ways in which the positron annihilation process operates in ionic crystals, semiconductors, metals and some condensed matter systems are analyzed. The scope of PAS is described and its prospects for the study of the electronic and defect structures are discussed. The applications of positron annihilation spectroscopy in radiation physics and chemistry of various substances as well as in physics and chemistry of solutions are exemplified. (instruments and methods of investigation)

  2. Heat load material studies: Simulated tokamak disruptions

    International Nuclear Information System (INIS)

    Gahl, J.M.; McDonald, J.M.; Zakharov, A.; Tserevitinov, S.; Barabash, V.; Guseva, M.

    1991-01-01

    It is clear that an improved understanding of the effects of tokamak disruptions on plasma facing component materials is needed for the ITER program. very large energy fluxes are predicted to be deposited in ITER and could be very damaging to the machine. During 1991, Sandia National Laboratories and the University of New Mexico conducted cooperative tokamak disruption simulation experiments at several Soviet facilities. These facilities were located at the Efremov Institute in Leningrad, the Kurchatov Atomic Energy Institute (Troisk and Moscow) and the Institute for Physical Chemistry of the Soviet Adademy of Sciences in Moscow. Erosion of graphite from plasma stream impact is seen to be much less than that observed with laser or electron beams with similar energy fluxes. This, along with other data obtained, seem to suggest that the ''vapor shielding'' effect is a very important phenomenon in the study of graphite erosion during tokamak disruption

  3. Sorption studies of radioelements on geological materials

    International Nuclear Information System (INIS)

    Berry, John A.; Yui, Mikazu; Kitamura, Akira

    2007-11-01

    Batch sorption experiments have been carried out to study the sorption of uranium, technetium, curium, neptunium, actinium, protactinium, polonium, americium and plutonium onto bentonite, granodiorite and tuff. Mathematical modelling using the HARPHRQ program and the HATCHES database was carried out to predict the speciation of uranium and technetium in the equilibrated seawater, and neptunium, americium and plutonium in the rock equilibrated water. Review of the literature for thermodynamic data for curium, actinium, protactinium and polonium was carried out. Where sufficient data were available, predictions of the speciation and solubility were made. This report is a summary report of the experimental work conducted by AEA Technology during April 1991-March 1998, and the main results have been presented at Material Research Society Symposium Proceedings and published as proceedings of them. (author)

  4. Integrated Computational Materials Engineering Development of Advanced High Strength Steel for Lightweight Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Hector, Jr., Louis G. [General Motors, Warren, MI (United States); McCarty, Eric D. [United States Automotive Materials Partnership LLC (USAMP), Southfield, MI (United States)

    2017-07-31

    The goal of the ICME 3GAHSS project was to successfully demonstrate the applicability of Integrated Computational Materials Engineering (ICME) for the development and deployment of third generation advanced high strength steels (3GAHSS) for immediate weight reduction in passenger vehicles. The ICME approach integrated results from well-established computational and experimental methodologies to develop a suite of material constitutive models (deformation and failure), manufacturing process and performance simulation modules, a properties database, as well as the computational environment linking them together for both performance prediction and material optimization. This is the Final Report for the ICME 3GAHSS project, which achieved the fol-lowing objectives: 1) Developed a 3GAHSS ICME model, which includes atomistic, crystal plasticity, state variable and forming models. The 3GAHSS model was implemented in commercially available LS-DYNA and a user guide was developed to facilitate use of the model. 2) Developed and produced two 3GAHSS alloys using two different chemistries and manufacturing processes, for use in calibrating and validating the 3GAHSS ICME Model. 3) Optimized the design of an automotive subassembly by substituting 3GAHSS for AHSS yielding a design that met or exceeded all baseline performance requirements with a 30% mass savings. A technical cost model was also developed to estimate the cost per pound of weight saved when substituting 3GAHSS for AHSS. The project demonstrated the potential for 3GAHSS to achieve up to 30% weight savings in an automotive structure at a cost penalty of up to $0.32 to $1.26 per pound of weight saved. The 3GAHSS ICME Model enables the user to design 3GAHSS to desired mechanical properties in terms of strength and ductility.

  5. Students' Computing Use and Study: When More is Less

    Directory of Open Access Journals (Sweden)

    Christine A McLachlan

    2016-02-01

    Full Text Available Since the turn of the century there has been a steady decline in enrolments of students in senior secondary computing classes in Australia. A flow on effect has seen reduced enrolments in tertiary computing courses and the subsequent predictions of shortages in skilled computing professionals. This paper investigates the relationship between students’ computing literacy levels, their use and access to computing tools, and students’ interest in and attitudes to formal computing study. Through the use of secondary data obtained from Australian and international reports, a reverse effect was discovered indicating that the more students used computing tools, the less interested they become in computing studies. Normal 0 false false false EN-AU X-NONE X-NONE

  6. Characterization of nanophase materials by x-ray diffraction and computer simulation

    International Nuclear Information System (INIS)

    Eastman, J.A.; Thompson, L.J.

    1989-06-01

    X-ray diffraction experiments on nanophase Pd have been performed with the primary goal of determining the nature of grain boundary structures in nanophase materials. A kinematical diffraction analysis has been developed to interpret x-ray θ--2θ data by comparing actual scans with scans produced by computer simulation. This simulation program has been used to explore the effects on diffracted intensity of a variety of microstructural and grain boundary structural parameters such as void concentration, grain size, grain boundary width, and changes in interplanar spacing and density in grain boundary regions. It has been found that a reasonable match to experimental data is produced by at least two model structures; in one, the material contains randomly positioned voids or vacancies, while in the other, the interplanar spacings in grain boundary regions are varied with respect to the spacings found in the grain interiors. 7 refs., 4 figs

  7. Computation of Casimir interactions between arbitrary three-dimensional objects with arbitrary material properties

    International Nuclear Information System (INIS)

    Reid, M. T. Homer; White, Jacob; Johnson, Steven G.

    2011-01-01

    We extend a recently introduced method for computing Casimir forces between arbitrarily shaped metallic objects [M. T. H. Reid et al., Phys. Rev. Lett. 103 040401 (2009)] to allow treatment of objects with arbitrary material properties, including imperfect conductors, dielectrics, and magnetic materials. Our original method considered electric currents on the surfaces of the interacting objects; the extended method considers both electric and magnetic surface current distributions, and obtains the Casimir energy of a configuration of objects in terms of the interactions of these effective surface currents. Using this new technique, we present the first predictions of Casimir interactions in several experimentally relevant geometries that would be difficult to treat with any existing method. In particular, we investigate Casimir interactions between dielectric nanodisks embedded in a dielectric fluid; we identify the threshold surface-surface separation at which finite-size effects become relevant, and we map the rotational energy landscape of bound nanoparticle diclusters.

  8. The history of theoretical, material and computational mechanics mathematics meets mechanics and engineering

    CERN Document Server

    2014-01-01

    This collection of 23 articles is the output of lectures in special sessions on “The History of Theoretical, Material and Computational Mechanics” within the yearly conferences of the GAMM in the years 2010 in Karlsruhe, Germany, 2011 in Graz, Austria, and in 2012 in Darmstadt, Germany; GAMM is the “Association for Applied Mathematics and Mechanics”, founded in 1922 by Ludwig Prandtl and Richard von Mises. The contributions in this volume discuss different aspects of mechanics. They are related to solid and fluid mechanics in general and to specific problems in these areas including the development of numerical solution techniques. In the first part the origins and developments of conservation principles in mechanics and related variational methods are treated together with challenging applications from the 17th to the 20th century. Part II treats general and more specific aspects of material theories of deforming solid continua and porous soils. and Part III presents important theoretical and enginee...

  9. Writing Apprehension, Computer Anxiety and Telecomputing: A Pilot Study.

    Science.gov (United States)

    Harris, Judith; Grandgenett, Neal

    1992-01-01

    A study measured graduate students' writing apprehension and computer anxiety levels before and after using electronic mail, computer conferencing, and remote database searching facilities during an educational technology course. Results indicted postcourse computer anxiety levels significantly related to usage statistics. Precourse writing…

  10. Experimental and computational studies of nanofluids

    Science.gov (United States)

    Vajjha, Ravikanth S.

    The goals of this dissertation were (i) to experimentally investigate the fluid dynamic and heat transfer performance of nanofluids in a circular tube, (ii) to study the influence of temperature and particle volumetric concentration of nanofluids on thermophysical properties, heat transfer and pumping power, (iii) to measure the rheological properties of various nanofluids and (iv) to investigate using a computational fluid dynamic (CFD) technique the performance of nanofluids in the flat tube of a radiator. Nanofluids are a new class of fluids prepared by dispersing nanoparticles with average sizes of less than 100 nm in traditional heat transfer fluids such as water, oil, ethylene glycol and propylene glycol. In cold regions of the world, the choice of base fluid for heat transfer applications is an ethylene glycol or propylene glycol mixed with water in different proportions. In the present research, a 60% ethylene glycol (EG) or propylene glycol (PG) and 40% water (W) by mass fluid mixture (60:40 EG/W or 60:40 PG/W) was used as a base fluid, which provides freeze protection to a very low level of temperature. Experiments were conducted to measure the convective heat transfer coefficient and pressure loss of nanofluids flowing in a circular tube in the fully developed turbulent regime. The experimental measurements were carried out for aluminum oxide (Al2O3), copper oxide (CuO) and silicon dioxide (SiO2) nanoparticles dispersed in 60:40 EG/W base fluid. Experiments revealed that the heat transfer coefficient of nanofluids showed an increase with the particle volumetric concentration. Pressure loss was also observed to increase with the nanoparticle volumetric concentration. New correlations for the Nusselt number and the friction factor were developed. The effects of temperature and particle volumetric concentration on different thermophysical properties (e.g. viscosity, thermal conductivity, specific heat and density) and subsequently on the Prandtl number

  11. Developing Materials Processing to Performance Modeling Capabilities and the Need for Exascale Computing Architectures (and Beyond)

    Energy Technology Data Exchange (ETDEWEB)

    Schraad, Mark William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Physics and Engineering Models; Luscher, Darby Jon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Advanced Simulation and Computing

    2016-09-06

    Additive Manufacturing techniques are presenting the Department of Energy and the NNSA Laboratories with new opportunities to consider novel component production and repair processes, and to manufacture materials with tailored response and optimized performance characteristics. Additive Manufacturing technologies already are being applied to primary NNSA mission areas, including Nuclear Weapons. These mission areas are adapting to these new manufacturing methods, because of potential advantages, such as smaller manufacturing footprints, reduced needs for specialized tooling, an ability to embed sensing, novel part repair options, an ability to accommodate complex geometries, and lighter weight materials. To realize the full potential of Additive Manufacturing as a game-changing technology for the NNSA’s national security missions; however, significant progress must be made in several key technical areas. In addition to advances in engineering design, process optimization and automation, and accelerated feedstock design and manufacture, significant progress must be made in modeling and simulation. First and foremost, a more mature understanding of the process-structure-property-performance relationships must be developed. Because Additive Manufacturing processes change the nature of a material’s structure below the engineering scale, new models are required to predict materials response across the spectrum of relevant length scales, from the atomistic to the continuum. New diagnostics will be required to characterize materials response across these scales. And not just models, but advanced algorithms, next-generation codes, and advanced computer architectures will be required to complement the associated modeling activities. Based on preliminary work in each of these areas, a strong argument for the need for Exascale computing architectures can be made, if a legitimate predictive capability is to be developed.

  12. Multiscale study on hydrogen mobility in metallic fusion divertor material

    International Nuclear Information System (INIS)

    Heinola, K.

    2010-01-01

    For achieving efficient fusion energy production, the plasma-facing wall materials of the fusion reactor should ensure long time operation. In the next step fusion device, ITER, the first wall region facing the highest heat and particle load, i.e. the divertor area, will mainly consist of tiles based on tungsten. During the reactor operation, the tungsten material is slowly but inevitably saturated with tritium. Tritium is the relatively short-lived hydrogen isotope used in the fusion reaction. The amount of tritium retained in the wall materials should be minimized and its recycling back to the plasma must be unrestrained, otherwise it cannot be used for fueling the plasma. A very expensive and thus economically not viable solution is to replace the first walls quite often. A better solution is to heat the walls to temperatures where tritium is released. Unfortunately, the exact mechanisms of hydrogen release in tungsten are not known. In this thesis both experimental and computational methods have been used for studying the release and retention of hydrogen in tungsten. The experimental work consists of hydrogen implantations into pure polycrystalline tungsten, the determination of the hydrogen concentrations using ion beam analyses (IBA) and monitoring the out-diffused hydrogen gas with thermodesorption spectrometry (TDS) as the tungsten samples are heated at elevated temperatures. Combining IBA methods with TDS, the retained amount of hydrogen is obtained as well as the temperatures needed for the hydrogen release. With computational methods the hydrogen-defect interactions and implantation-induced irradiation damage can be examined at the atomic level. The method of multiscale modelling combines the results obtained from computational methodologies applicable at different length and time scales. Electron density functional theory calculations were used for determining the energetics of the elementary processes of hydrogen in tungsten, such as diffusivity and

  13. [Experimental and computation studies of polar solvation

    International Nuclear Information System (INIS)

    1990-01-01

    This report from the Pennsylvania State University contains seven sections: (1) radiative rate effects in solvatlvatochromic probes; (2) intramolecular charge transfer reactions; (3) Solvation dynamics in low temperature alcohols; (4) Ionic solvation dynamics; (5) solvation and proton-transfer dynamics in 7-azaindole; (6) computer simulations of solvation dynamics; (7) solvation in supercritical fluids. 20 refs., 11 figs

  14. Biomedical Visual Computing: Case Studies and Challenges

    KAUST Repository

    Johnson, Christopher

    2012-01-01

    Advances in computational geometric modeling, imaging, and simulation let researchers build and test models of increasing complexity, generating unprecedented amounts of data. As recent research in biomedical applications illustrates, visualization will be critical in making this vast amount of data usable; it\\'s also fundamental to understanding models of complex phenomena. © 2012 IEEE.

  15. Biomedical Visual Computing: Case Studies and Challenges

    KAUST Repository

    Johnson, Christopher

    2012-01-01

    Advances in computational geometric modeling, imaging, and simulation let researchers build and test models of increasing complexity, generating unprecedented amounts of data. As recent research in biomedical applications illustrates, visualization will be critical in making this vast amount of data usable; it's also fundamental to understanding models of complex phenomena. © 2012 IEEE.

  16. Spring 2005 Industry Study. Strategic Materials

    National Research Council Canada - National Science Library

    Boland, Michael; Bromell, Robert; Carpenter, Robert; Clark, Thomas; Donnelly, Thomas; Echernacht, Jr., Kenneth; Higgins, David; Madden, Michael; Martin, Matthew; Murdock, Hal

    2005-01-01

    .... In order to retain its competitive advantage, the US must initiate a comprehensive National Materials Strategy to focus and revitalize the climate for innovation, to develop strategic partnerships...

  17. Computed tomographic images using tube source of x rays: interior properties of the material

    Science.gov (United States)

    Rao, Donepudi V.; Takeda, Tohoru; Itai, Yuji; Seltzer, S. M.; Hubbell, John H.; Zeniya, Tsutomu; Akatsuka, Takao; Cesareo, Roberto; Brunetti, Antonio; Gigante, Giovanni E.

    2002-01-01

    An image intensifier based computed tomography scanner and a tube source of x-rays are used to obtain the images of small objects, plastics, wood and soft materials in order to know the interior properties of the material. A new method is developed to estimate the degree of monochromacy, total solid angle, efficiency and geometrical effects of the measuring system and the way to produce monoenergetic radiation. The flux emitted by the x-ray tube is filtered using the appropriate filters at the chosen optimum energy and reasonable monochromacy is achieved and the images are acceptably distinct. Much attention has been focused on the imaging of small objects of weakly attenuating materials at optimum value. At optimum value it is possible to calculate the three-dimensional representation of inner and outer surfaces of the object. The image contrast between soft materials could be significantly enhanced by optimal selection of the energy of the x-rays by Monte Carlo methods. The imaging system is compact, reasonably economic, has a good contrast resolution, simple operation and routine availability and explores the use of optimizing tomography for various applications.

  18. Computational Magnetohydrodynamics of General Materials in Generalized Coordinates and Applications to Laser-Target Interactions

    Science.gov (United States)

    MacGillivray, Jeff T.; Peterkin, Robert E., Jr.

    2003-10-01

    We have developed a multiblock arbitrary coordinate Hydromagnetics (MACH) code for computing the time-evolution of materials of arbitrary phase (solid, liquid, gas, and plasma) in response to forces that arise from material and magnetic pressures. MACH is a single-fluid, time-dependent, arbitrary Lagrangian-Eulerian (ALE) magnetohydrodynamic (MHD) simulation environment. The 2 1/2 -dimensional MACH2 and the parallel 3-D MACH3 are widely used in the MHD community to perform accurate simulation of the time evolution of electrically conducting materials in a wide variety of laboratory situations. In this presentation, we discuss simulations of the interaction of an intense laser beam with a solid target in an ambient gas. Of particular interest to us is a laser-supported detonation wave (blast wave) that originates near the surface of the target when the laser intensity is sufficiently large to vaporize target material within the focal spot of the beam. Because the MACH3 simulations are fully three-dimensional, we are able to simulate non-normal laser incidence. A magnetic field is also produced from plasma energy near the edge of the focal spot.

  19. WE-FG-207B-02: Material Reconstruction for Spectral Computed Tomography with Detector Response Function

    International Nuclear Information System (INIS)

    Liu, J; Gao, H

    2016-01-01

    Purpose: Different from the conventional computed tomography (CT), spectral CT based on energy-resolved photon-counting detectors is able to provide the unprecedented material composition. However, an important missing piece for accurate spectral CT is to incorporate the detector response function (DRF), which is distorted by factors such as pulse pileup and charge-sharing. In this work, we propose material reconstruction methods for spectral CT with DRF. Methods: The polyenergetic X-ray forward model takes the DRF into account for accurate material reconstruction. Two image reconstruction methods are proposed: a direct method based on the nonlinear data fidelity from DRF-based forward model; a linear-data-fidelity based method that relies on the spectral rebinning so that the corresponding DRF matrix is invertible. Then the image reconstruction problem is regularized with the isotropic TV term and solved by alternating direction method of multipliers. Results: The simulation results suggest that the proposed methods provided more accurate material compositions than the standard method without DRF. Moreover, the proposed method with linear data fidelity had improved reconstruction quality from the proposed method with nonlinear data fidelity. Conclusion: We have proposed material reconstruction methods for spectral CT with DRF, whichprovided more accurate material compositions than the standard methods without DRF. Moreover, the proposed method with linear data fidelity had improved reconstruction quality from the proposed method with nonlinear data fidelity. Jiulong Liu and Hao Gao were partially supported by the NSFC (#11405105), the 973 Program (#2015CB856000), and the Shanghai Pujiang Talent Program (#14PJ1404500).

  20. COMPUTING

    CERN Multimedia

    I. Fisk

    2013-01-01

    Computing activity had ramped down after the completion of the reprocessing of the 2012 data and parked data, but is increasing with new simulation samples for analysis and upgrade studies. Much of the Computing effort is currently involved in activities to improve the computing system in preparation for 2015. Operations Office Since the beginning of 2013, the Computing Operations team successfully re-processed the 2012 data in record time, not only by using opportunistic resources like the San Diego Supercomputer Center which was accessible, to re-process the primary datasets HTMHT and MultiJet in Run2012D much earlier than planned. The Heavy-Ion data-taking period was successfully concluded in February collecting almost 500 T. Figure 3: Number of events per month (data) In LS1, our emphasis is to increase efficiency and flexibility of the infrastructure and operation. Computing Operations is working on separating disk and tape at the Tier-1 sites and the full implementation of the xrootd federation ...

  1. A model ecosystem experiment and its computational simulation studies

    International Nuclear Information System (INIS)

    Doi, M.

    2002-01-01

    Simplified microbial model ecosystem and its computer simulation model are introduced as eco-toxicity test for the assessment of environmental responses from the effects of environmental impacts. To take the effects on the interactions between species and environment into account, one option is to select the keystone species on the basis of ecological knowledge, and to put it in the single-species toxicity test. Another option proposed is to put the eco-toxicity tests as experimental micro ecosystem study and a theoretical model ecosystem analysis. With these tests, the stressors which are more harmful to the ecosystems should be replace with less harmful ones on the basis of unified measures. Management of radioactive materials, chemicals, hyper-eutrophic, and other artificial disturbances of ecosystem should be discussed consistently from the unified view point of environmental protection. (N.C.)

  2. Computational domain discretization in numerical analysis of flow within granular materials

    Science.gov (United States)

    Sosnowski, Marcin

    2018-06-01

    The discretization of computational domain is a crucial step in Computational Fluid Dynamics (CFD) because it influences not only the numerical stability of the analysed model but also the agreement of obtained results and real data. Modelling flow in packed beds of granular materials is a very challenging task in terms of discretization due to the existence of narrow spaces between spherical granules contacting tangentially in a single point. Standard approach to this issue results in a low quality mesh and unreliable results in consequence. Therefore the common method is to reduce the diameter of the modelled granules in order to eliminate the single-point contact between the individual granules. The drawback of such method is the adulteration of flow and contact heat resistance among others. Therefore an innovative method is proposed in the paper: single-point contact is extended to a cylinder-shaped volume contact. Such approach eliminates the low quality mesh elements and simultaneously introduces only slight distortion to the flow as well as contact heat transfer. The performed analysis of numerous test cases prove the great potential of the proposed method of meshing the packed beds of granular materials.

  3. Study of nuclear environment and material strategy

    International Nuclear Information System (INIS)

    Kamei, Takashi

    2011-01-01

    There is a concern about the environmental hazard caused by radioactive materials coming with the expansion of nuclear power and even by renewable energies, which are used as countermeasures against global warming to construct a sustainable society. A concept to internalize the pollution caused by radioactive materials, which are directly or indirectly related to nuclear power, to economical activities by adopting externality is proposed. Energy and industrial productions are strongly related to the supply of material. Therefore material flow is also part of this internalization concept. The concept is named 'NEMS (Nuclear Environment and Material Strategy)'. Fission products and transuranic isotopes from nuclear power such as plutonium are considered in this concept. Thorium, which comes from the material flow of rare-earth production to support the elaboration of renewable energies including electric vehicles on the consumer side, is considered as an externality of the non-nuclear power field. Fission products contain some rare-earth materials. Thus, these rare-earth materials, which are extracted by the advanced ORIENT (Optimization by Recycling Instructive Elements) cycle, are internalized as rare-earth supplier in economy. However, the supply quantity is limited. Therefore rare-earth production itself is still needed. The externality of rare-earth production is thorium and is internalized by using it as nuclear fuel. In this case, the demand of thorium is still small within these few decades compared to the production of thorium as byproduct of the rare-earth production. A thorium energy bank (The Bank) is advanced to regulate the storage of the excess amount of thorium inside of an international framework in order to prevent environmental hazard resulting from the illegal disposal of thorium. In this paper, the material flows of thorium and rare-earth are outlined. Their material balance are demonstrated based on the prediction of rare-earth mining and an

  4. Optimization Using Metamodeling in the Context of Integrated Computational Materials Engineering (ICME)

    Energy Technology Data Exchange (ETDEWEB)

    Hammi, Youssef; Horstemeyer, Mark F; Wang, Paul; David, Francis; Carino, Ricolindo

    2013-11-18

    Predictive Design Technologies, LLC (PDT) proposed to employ Integrated Computational Materials Engineering (ICME) tools to help the manufacturing industry in the United States regain the competitive advantage in the global economy. ICME uses computational materials science tools within a holistic system in order to accelerate materials development, improve design optimization, and unify design and manufacturing. With the advent of accurate modeling and simulation along with significant increases in high performance computing (HPC) power, virtual design and manufacturing using ICME tools provide the means to reduce product development time and cost by alleviating costly trial-and-error physical design iterations while improving overall quality and manufacturing efficiency. To reduce the computational cost necessary for the large-scale HPC simulations and to make the methodology accessible for small and medium-sized manufacturers (SMMs), metamodels are employed. Metamodels are approximate models (functional relationships between input and output variables) that can reduce the simulation times by one to two orders of magnitude. In Phase I, PDT, partnered with Mississippi State University (MSU), demonstrated the feasibility of the proposed methodology by employing MSU?s internal state variable (ISV) plasticity-damage model with the help of metamodels to optimize the microstructure-process-property-cost for tube manufacturing processes used by Plymouth Tube Company (PTC), which involves complicated temperature and mechanical loading histories. PDT quantified the microstructure-property relationships for PTC?s SAE J525 electric resistance-welded cold drawn low carbon hydraulic 1010 steel tube manufacturing processes at seven different material states and calibrated the ISV plasticity material parameters to fit experimental tensile stress-strain curves. PDT successfully performed large scale finite element (FE) simulations in an HPC environment using the ISV plasticity

  5. Computation of Thermodynamic Equilibria Pertinent to Nuclear Materials in Multi-Physics Codes

    Science.gov (United States)

    Piro, Markus Hans Alexander

    Nuclear energy plays a vital role in supporting electrical needs and fulfilling commitments to reduce greenhouse gas emissions. Research is a continuing necessity to improve the predictive capabilities of fuel behaviour in order to reduce costs and to meet increasingly stringent safety requirements by the regulator. Moreover, a renewed interest in nuclear energy has given rise to a "nuclear renaissance" and the necessity to design the next generation of reactors. In support of this goal, significant research efforts have been dedicated to the advancement of numerical modelling and computational tools in simulating various physical and chemical phenomena associated with nuclear fuel behaviour. This undertaking in effect is collecting the experience and observations of a past generation of nuclear engineers and scientists in a meaningful way for future design purposes. There is an increasing desire to integrate thermodynamic computations directly into multi-physics nuclear fuel performance and safety codes. A new equilibrium thermodynamic solver is being developed with this matter as a primary objective. This solver is intended to provide thermodynamic material properties and boundary conditions for continuum transport calculations. There are several concerns with the use of existing commercial thermodynamic codes: computational performance; limited capabilities in handling large multi-component systems of interest to the nuclear industry; convenient incorporation into other codes with quality assurance considerations; and, licensing entanglements associated with code distribution. The development of this software in this research is aimed at addressing all of these concerns. The approach taken in this work exploits fundamental principles of equilibrium thermodynamics to simplify the numerical optimization equations. In brief, the chemical potentials of all species and phases in the system are constrained by estimates of the chemical potentials of the system

  6. Study of Neutron Induced Effects in Nuclear Materials by Computer Simulation: Ultra-Fast Solidification at the Nanoscopic Scale; Estudio de Efectos Inducidos por Neutrones en Materiales de Interes Nuclear Mediante Simulaciones por Computadora: Solidificacion Ultra Rapida a Escala Nanoscopica

    Energy Technology Data Exchange (ETDEWEB)

    Lopasso, Edmundo [Comision Nacional de Energia Atomica, Centro Atomico Bariloche, Dept. de Ingenieria Nuclear e Investigacion Aplicada (Argentina)

    2003-07-01

    In the present study we analyze some of the aspects on the primary damage induced by radiation in metals, specially Fe based alloys with low Cu content used in nuclear reactors.Atomic scale simulations with Molecular Dynamics and Monte Carlo methods were applied on the basis of interatomic potentials available in the literature. The Fe-Cu phase diagram was evaluated in the whole compositional range, and the phase and solubility limits as predicted by the model interactions were determined.Results, as compared to experimental findings, suggest that a better description of the potentials of the elements is needed, and that the description of the relative solubility of the solid phases should be included in the potentials.Even under these limitations, the solid-liquid phase limits in the Fe rich region are correctly represented, and the results are used to interpret the behaviour of Cu as solute in Fe during the cooling of displacement cascades.The analysis was performed with the aid of the results on the Ni-Au system, whose thermodynamic and solute transport properties are correctly described by interatomic potentials.This allowed us to separate the relative effects of thermal gradients and phase diagram characteristics on the solute redistribution.From the results on the Ni-Au system and dilute alloys of Cu in Fe, it is concluded that thermal gradients have an influence on solute redistribution, which migrate to the high temperature regions if the solute mass is lower than the solvent mass, while the opposite occurs if the solute mass is higher than the solvent one.This effect is known as thermomigration, and acts during the cooling down after the interaction of radiation with matter depending on the characteristic property known as heat of transport.By comparing different cooling rates in Ni-5%Au it is concluded that the phase diagram will have an effect on solute redistribution if the equilibrium partition ratio between the solidus and liquidus lines is low enough

  7. Highly efficient computer algorithm for identifying layer thickness of atomically thin 2D materials

    Science.gov (United States)

    Lee, Jekwan; Cho, Seungwan; Park, Soohyun; Bae, Hyemin; Noh, Minji; Kim, Beom; In, Chihun; Yang, Seunghoon; Lee, Sooun; Seo, Seung Young; Kim, Jehyun; Lee, Chul-Ho; Shim, Woo-Young; Jo, Moon-Ho; Kim, Dohun; Choi, Hyunyong

    2018-03-01

    The fields of layered material research, such as transition-metal dichalcogenides (TMDs), have demonstrated that the optical, electrical and mechanical properties strongly depend on the layer number N. Thus, efficient and accurate determination of N is the most crucial step before the associated device fabrication. An existing experimental technique using an optical microscope is the most widely used one to identify N. However, a critical drawback of this approach is that it relies on extensive laboratory experiences to estimate N; it requires a very time-consuming image-searching task assisted by human eyes and secondary measurements such as atomic force microscopy and Raman spectroscopy, which are necessary to ensure N. In this work, we introduce a computer algorithm based on the image analysis of a quantized optical contrast. We show that our algorithm can apply to a wide variety of layered materials, including graphene, MoS2, and WS2 regardless of substrates. The algorithm largely consists of two parts. First, it sets up an appropriate boundary between target flakes and substrate. Second, to compute N, it automatically calculates the optical contrast using an adaptive RGB estimation process between each target, which results in a matrix with different integer Ns and returns a matrix map of Ns onto the target flake position. Using a conventional desktop computational power, the time taken to display the final N matrix was 1.8 s on average for the image size of 1280 pixels by 960 pixels and obtained a high accuracy of 90% (six estimation errors among 62 samples) when compared to the other methods. To show the effectiveness of our algorithm, we also apply it to TMD flakes transferred on optically transparent c-axis sapphire substrates and obtain a similar result of the accuracy of 94% (two estimation errors among 34 samples).

  8. X-ray Computed Microtomography technique applied for cementitious materials: A review.

    Science.gov (United States)

    da Silva, Ítalo Batista

    2018-04-01

    The main objective of this article is to present a bibliographical review about the use of the X-ray microtomography method in 3D images processing of cementitious materials microstructure, analyzing the pores microstructure and connectivity network, enabling tthe possibility of building a relationship between permeability and porosity. The use of this technique enables the understanding of physical, chemical and mechanical properties of cementitious materials by publishing good results, considering that the quality and quantity of accessible information were significant and may contribute to the study of cementitious materials development. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Advanced Computational Materials Science: Application to Fusion and Generation IV Fission Reactors (Workshop Report)

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, RE

    2004-07-15

    The ''Workshop on Advanced Computational Materials Science: Application to Fusion and Generation IV Fission Reactors'' was convened to determine the degree to which an increased effort in modeling and simulation could help bridge the gap between the data that is needed to support the implementation of these advanced nuclear technologies and the data that can be obtained in available experimental facilities. The need to develop materials capable of performing in the severe operating environments expected in fusion and fission (Generation IV) reactors represents a significant challenge in materials science. There is a range of potential Gen-IV fission reactor design concepts and each concept has its own unique demands. Improved economic performance is a major goal of the Gen-IV designs. As a result, most designs call for significantly higher operating temperatures than the current generation of LWRs to obtain higher thermal efficiency. In many cases, the desired operating temperatures rule out the use of the structural alloys employed today. The very high operating temperature (up to 1000 C) associated with the NGNP is a prime example of an attractive new system that will require the development of new structural materials. Fusion power plants represent an even greater challenge to structural materials development and application. The operating temperatures, neutron exposure levels and thermo-mechanical stresses are comparable to or greater than those for proposed Gen-IV fission reactors. In addition, the transmutation products created in the structural materials by the high energy neutrons produced in the DT plasma can profoundly influence the microstructural evolution and mechanical behavior of these materials. Although the workshop addressed issues relevant to both Gen-IV and fusion reactor materials, much of the discussion focused on fusion; the same focus is reflected in this report. Most of the physical models and computational methods

  10. Optimizing Classroom Acoustics Using Computer Model Studies.

    Science.gov (United States)

    Reich, Rebecca; Bradley, John

    1998-01-01

    Investigates conditions relating to the maximum useful-to-detrimental sound ratios present in classrooms and determining the optimum conditions for speech intelligibility. Reveals that speech intelligibility is more strongly influenced by ambient noise levels and that the optimal location for sound absorbing material is on a classroom's upper…

  11. Positive muon studies of magnetic materials

    International Nuclear Information System (INIS)

    Patterson, B.D.

    1975-01-01

    Polarized positive muons (μ + ) are stopped in magnetic materials, and the μ + precession is observed via the muons's asymmetric decay to a positron. The precession frequency is a measure of the local magnetic field at the μ + . Relaxation of the μ + spin is caused by spatially or time-varying local fields. The local field at a stopped μ + in ferromagnetic nickel is measured. From this measurement, the hyperfine field seen by an interstitial μ + due to its contact interaction with polarized screening electrons is inferred to be -0.66kG. A discussion of this value in terms of a simple model for the screening configuration is presented. Critical spin fluctuations in Ni at temperatures just above the Curie point rapidly relax the μ + spin. The temperature and external magnetic field dependence of the relaxation rate is determined experimentally. A theory for the relaxation rate is presented which demonstrates the importance of the hyperfine and dipolar interactions of the μ + with its Ni host. Preliminary results on μ + studies in ferromagnetic iron and cobalt are also discussed. (U.S.)

  12. Building a Unified Computational Model for the Resonant X-Ray Scattering of Strongly Correlated Materials

    Energy Technology Data Exchange (ETDEWEB)

    Bansil, Arun [Northeastern Univ., Boston, MA (United States)

    2016-12-01

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspects of this grand challenge of X-ray science. In particular, our Collaborative Research Team (CRT) focused on understanding and modeling of elastic and inelastic resonant X-ray scattering processes. We worked to unify the three different computational approaches currently used for modeling X-ray scattering—density functional theory, dynamical mean-field theory, and small-cluster exact diagonalization—to achieve a more realistic material-specific picture of the interaction between X-rays and complex matter. To achieve a convergence in the interpretation and to maximize complementary aspects of different theoretical methods, we concentrated on the cuprates, where most experiments have been performed. Our team included both US and international researchers, and it fostered new collaborations between researchers currently working with different approaches. In addition, we developed close relationships with experimental groups working in the area at various synchrotron facilities in the US. Our CRT thus helped toward enabling the US to assume a leadership role in the theoretical development of the field, and to create a global network and community of scholars dedicated to X-ray scattering research.

  13. Building a Unified Computational Model for the Resonant X-Ray Scattering of Strongly Correlated Materials

    International Nuclear Information System (INIS)

    Bansil, Arun

    2016-01-01

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspects of this grand challenge of X-ray science. In particular, our Collaborative Research Team (CRT) focused on understanding and modeling of elastic and inelastic resonant X-ray scattering processes. We worked to unify the three different computational approaches currently used for modeling X-ray scattering-density functional theory, dynamical mean-field theory, and small-cluster exact diagonalization-to achieve a more realistic material-specific picture of the interaction between X-rays and complex matter. To achieve a convergence in the interpretation and to maximize complementary aspects of different theoretical methods, we concentrated on the cuprates, where most experiments have been performed. Our team included both US and international researchers, and it fostered new collaborations between researchers currently working with different approaches. In addition, we developed close relationships with experimental groups working in the area at various synchrotron facilities in the US. Our CRT thus helped toward enabling the US to assume a leadership role in the theoretical development of the field, and to create a global network and community of scholars dedicated to X-ray scattering research.

  14. Influences of Light-emitting Diode Illumination Bleaching Technique on Nanohardness of Computer-aided Design and Computer-aided Manufacturing Ceramic Restorative Materials.

    Science.gov (United States)

    Juntavee, Niwut; Juntavee, Apa; Saensutthawijit, Phuwiwat

    2018-02-01

    This study evaluated the effect of light-emitting diode (LED) illumination bleaching technique on the surface nanohardness of various computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic materials. Twenty disk-shaped samples (width, length, and thickness = 10, 15, and 2 mm) were prepared from each of the ceramic materials for CAD/CAM, including Lava™ Ultimate (L V ), Vita Enamic® (E n ) IPS e.max® CAD (M e ), inCoris® TZI (I C ), and Prettau® zirconia (P r ). The samples from each type of ceramic were randomly divided into two groups based on the different bleaching techniques to be used on them, using 35% hydrogen peroxide with and without LED illumination. The ceramic disk samples were bleached according to the manufacturer's instruction. Surface hardness test was performed before and after bleaching using nanohardness tester with a Berkovich diamond indenter. The respective Vickers hardness number upon no bleaching and bleaching without or with LED illumination [mean ± standard deviation (SD)] for each type of ceramic were as follows: 102.52 ± 2.09, 101.04 ± 1.18, and 98.17 ± 1.15 for L V groups; 274.96 ± 5.41, 271.29 ± 5.94, and 268.20 ± 7.02 for E n groups; 640.74 ± 31.02, 631.70 ± 22.38, and 582.32 ± 33.88 for M e groups; 1,442.09 ± 35.07, 1,431.32 ± 28.80, and 1,336.51 ± 34.03 for I C groups; and 1,383.82 ± 33.87, 1,343.51 ± 38.75, and 1,295.96 ± 31.29 for P r groups. The results indicated surface hardness reduction following the bleaching procedure of varying degrees for different ceramic materials. Analysis of variance (ANOVA) revealed a significant reduction in surface hardness due to the effect of bleaching technique, ceramic material, and the interaction between bleaching technique and ceramic material (p LED illumination exhibited more reduction in surface hardness of dental ceramic than what was observed without LED illumination. Clinicians should consider protection of the existing restoration while bleaching.

  15. A computed tomographic study on epilepsy

    International Nuclear Information System (INIS)

    Bae, Hoon Sik

    1980-01-01

    140 patients with epileptic seizure were studied by computed tomography during the period from Feb. 1979 to Aug. 1979 in the Department or Radiology, College of Medicine, Hangyang University. Those findings on CT and clinical records including EEG findings were reviewed. The results were as follows: 1. Age distribution of the total 140 patients was broad ranging from 1 month to 63 years. 73.5% of patients was below the age of 30. The patient population was comprised of 93 males and 47 females, and its male to female ratio was 2 : 1. 2. The type of epileptic seizure were classified according to the International League against Epilepsy. 42.9% of patients had primary generalized seizure, 47.1% with partial seizure, and 10% with non classifiable seizure. 3. As additional symptoms and signs except seizure, headache was most common, and the next was nausea and vomiting. Uncommonly, there were also insomnia, personality change, and memory disturbance. 4. 37.1% of patients had less than 1 month of seizure history, 19.3% between 1 year and 5 years. 5. EEG findings were available in 41 patients, and normal in 15 cases. 26 patients revealed abnormal findings. Among those abnormal findings focal slowing was appeared in 19.5% and generalized slowing in 17.1%. 6. 52% of patients showed abnormal findings on CT. The most common abnormal findings was focal low density (30%), and the next was diffuse hydrocephalus (7.1%). After contrast infusion, contrast enhancement was occurred in cases with focal low density, focal high or isodense mass density. In patients with focal low density, ring or nodular enhancement were common, and diffuse or serpentime enhancement in focal high or isodence mass density. 7. The frequency of structural abnormalities on CT was more common in patients below the age of 10 and over 30 than other age groups. The epilepsy starting below 10 and over 30 years of age showed structural abnormalities in 63.6-100%. 8. The patients who had less than 6 months of

  16. A computed tomographic study on epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Hoon Sik [Hanyang University College of Medicine, Seoul (Korea, Republic of)

    1980-06-15

    140 patients with epileptic seizure were studied by computed tomography during the period from Feb. 1979 to Aug. 1979 in the Department or Radiology, College of Medicine, Hangyang University. Those findings on CT and clinical records including EEG findings were reviewed. The results were as follows: 1. Age distribution of the total 140 patients was broad ranging from 1 month to 63 years. 73.5% of patients was below the age of 30. The patient population was comprised of 93 males and 47 females, and its male to female ratio was 2 : 1. 2. The type of epileptic seizure were classified according to the International League against Epilepsy. 42.9% of patients had primary generalized seizure, 47.1% with partial seizure, and 10% with non classifiable seizure. 3. As additional symptoms and signs except seizure, headache was most common, and the next was nausea and vomiting. Uncommonly, there were also insomnia, personality change, and memory disturbance. 4. 37.1% of patients had less than 1 month of seizure history, 19.3% between 1 year and 5 years. 5. EEG findings were available in 41 patients, and normal in 15 cases. 26 patients revealed abnormal findings. Among those abnormal findings focal slowing was appeared in 19.5% and generalized slowing in 17.1%. 6. 52% of patients showed abnormal findings on CT. The most common abnormal findings was focal low density (30%), and the next was diffuse hydrocephalus (7.1%). After contrast infusion, contrast enhancement was occurred in cases with focal low density, focal high or isodense mass density. In patients with focal low density, ring or nodular enhancement were common, and diffuse or serpentime enhancement in focal high or isodence mass density. 7. The frequency of structural abnormalities on CT was more common in patients below the age of 10 and over 30 than other age groups. The epilepsy starting below 10 and over 30 years of age showed structural abnormalities in 63.6-100%. 8. The patients who had less than 6 months of

  17. Studies on gamma irradiated rubber materials

    Science.gov (United States)

    Lungu, I. B.; Stelescu, M. D.; Cutrubinis, M.

    2018-01-01

    Due to the increase in use and production of polymer materials, there is a constant pressure of finding a solution to more environmental friendly composites. Beside the constant effort of recycling used materials, it seems more appropriate to manufacture and use biodegradable and renewable row materials. Natural polymers like starch, cellulose, lignin etc are ideal for preparing biodegradable composites. Some of the dynamic markets that use polymer materials are the food and pharmaceutical industries. Because of their desinfastation and sometimes sterility requirements, different treatment processes are applied, one of it being radiation treatment. The scope of this paper is to analyze the mechanical behaviour of rubber based materials irradiated with gamma rays at four medium doses, 30.1 kGy, 60.6 kGy, 91 kGy and 121.8 kGy. The objectives are the following: to identify the optimum radiation dose in order to obtain a good mechanical behaviour and to identify the mechanical behaviour of the material when adding different quantities of natural filler (20 phr, 60 phr and 100 phr).

  18. Bayer Digester Optimization Studies using Computer Techniques

    Science.gov (United States)

    Kotte, Jan J.; Schleider, Victor H.

    Theoretically required heat transfer performance by the multistaged flash heat reclaim system of a high pressure Bayer digester unit is determined for various conditions of discharge temperature, excess flash vapor and indirect steam addition. Solution of simultaneous heat balances around the digester vessels and the heat reclaim system yields the magnitude of available heat for representation of each case on a temperature-enthalpy diagram, where graphical fit of the number of flash stages fixes the heater requirements. Both the heat balances and the trial-and-error graphical solution are adapted to solution by digital computer techniques.

  19. Computed tomographic study in children with microcephaly

    International Nuclear Information System (INIS)

    Ito, Masatoshi; Okuno, Takehiko; Mikawa, Haruki

    1989-01-01

    Computed tomographic (CT) brain scanning was performed on fifty-eight infants and children with microcephaly. CT scans were useful for detecting unsuspected brain lesions and for diagnosing underlying diseases. The head size did not correlate with the CT findings, the degree of mental retardation, or the existence of motor disturbance or epilepsy. On the other hand, the CT findings were correlated with the degree of mental retardation, and the existence of motor disturbance or epilepsy. CT scans were useful for determining the prognosis of the microcephaly. (author)

  20. A Monte Carlo computer code for evaluating energy loss of 10 keV to 10 MeV ions in amorphous silicon materials

    International Nuclear Information System (INIS)

    Erramli, H.; Elbounagui, O.; Misdaq, M.A.; Merzouki, A.

    2007-01-01

    The basic concepts of a computer simulation code for determining the energy loss of ions in the 10 keV to 10 MeV energy range in amorphous silicon materials were presented and discussed. Data obtained were found in good agreement with those obtained by using a SRIM programme. Electronic and nuclear energy losses were evaluated. Variation of the energy loss as a function of the incident ion energy were studied. This new computer code is a good tool for evaluating stopping powers of various materials for light and heavy ions

  1. Calorimetric and computational study of 7-hydroxycoumarin

    International Nuclear Information System (INIS)

    Sousa, Clara C.S.; Matos, M. Agostinha R.; Morais, Victor M.F.

    2011-01-01

    Highlights: → Experimental standard molar enthalpies of formation, sublimation of 7-hydroxycoumarin. → Combustion calorimetry, sublimation microcalorimetry, differential scanning calorimetry. → DFT calculations, MC3BB and MC3MPW methods have been performed for the compound and its isomers. → Computational estimation of enthalpies of formation of 5-, 6-, and 8-hydroxycoumarin. - Abstract: The standard (p o = 0.1 MPa) molar energy of combustion in oxygen, at T = 298.15 K, of 7-hydroxycoumarin was measured by static bomb calorimetry. The value of the standard molar enthalpy of sublimation was obtained by Calvet microcalorimetry and corrected to T = 298.15 K. Combining these results, the standard molar enthalpy of formation of the compound, in the gas phase, at T = 298.15 K, has been calculated, -(337.5 ± 2.3) kJ . mol -1 . The values for the temperature of fusion, T fusion , and for the fusion enthalpy, at T = T fusion , are also reported. Additionally, high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy functional with extended basis sets, the MC3BB and MC3MPW methods and more accurate correlated computational techniques of the MCCM suite have been performed for the compound. The agreement between experiment and theory gives confidence to estimate the enthalpy of formation of the remaining hydroxycoumarins substituted in the benzene ring.

  2. Study of New Materials Design based on Hadoop

    Directory of Open Access Journals (Sweden)

    Wu Jun

    2016-01-01

    Full Text Available With the rapid development of information technology, the scientific research shows that the data mining and other information technology could be used in the design of new materials. It is explicit that Intelligent Materials research focuses on using physical and chemical principles combined with computer techniques such as Big Data, Cloud computing and Intelligent modeling and simulation to solve chemical problems. In this paper, based on the cluster based outlier algorithm as the main body, this paper discusses the definition New Materials research In the Hadoop cloud platform, and the parallel processing of Map-Reduce model. The performance this model of new material was established by using the method of Map-Reduction provided the basis for the performance optimization.

  3. A database for CO2 Separation Performances of MOFs based on Computational Materials Screening.

    Science.gov (United States)

    Altintas, Cigdem; Avci, Gokay; Daglar, Hilal; Nemati Vesali Azar, Ayda; Velioglu, Sadiye; Erucar, Ilknur; Keskin, Seda

    2018-05-03

    Metal organic frameworks (MOFs) have been considered as great candidates for CO2 capture. Considering the very large number of available MOFs, high-throughput computational screening plays a critical role in identifying the top performing materials for target applications in a time-effective manner. In this work, we used molecular simulations to screen the most recent and complete MOF database for identifying the most promising materials for CO2 separation from flue gas (CO2/N2) and landfill gas (CO2/CH4) under realistic operating conditions. We first validated our approach by comparing the results of our molecular simulations for the CO2 uptakes, CO2/N2 and CO2/CH4 selectivities of various types of MOFs with the available experimental data. We then computed binary CO2/N2 and CO2/CH4 mixture adsorption data for the entire MOF database and used these results to calculate several adsorbent selection metrics such as selectivity, working capacity, adsorbent performance score, regenerability, and separation potential. MOFs were ranked based on the combination of these metrics and the top performing MOF adsorbents that can achieve CO2/N2 and CO2/CH4 separations with high performance were identified. Molecular simulations for the adsorption of a ternary CO2/N2/CH4 mixture were performed for these top materials in order to provide a more realistic performance assessment of MOF adsorbents. Structure-performance analysis showed that MOFs with ΔQ>30 kJ/mol, 3.8 A≤PLD≤5 A, 5 A≤LCD≤7.5 A, 0.5≤ϕ≤0.75, SA≤1,000 m2/g, ρ>1 g/cm 3 are the best candidates for selective separation of CO2 from flue gas and landfill gas. This information will be very useful to design novel MOFs with the desired structural features that can lead to high CO2 separation potentials. Finally, an online, freely accessible database https://cosmoserc.ku.edu.tr was established, for the first time in the literature, which reports all computed adsorbent metrics of 3,816 MOFs for CO2/N2, CO2/CH4

  4. Study on Thermal Conductivity of Personal Computer Aluminum-Magnesium Alloy Casing

    Science.gov (United States)

    Liao, MeiHong

    With the rapid development of computer technology, micro-state atoms by simulating the movement of material to analyze the nature of the macro-state have become an important subject. Materials, especially aluminium-magnesium alloy materials, often used in personal computer case, this article puts forward heat conduction model of the material, and numerical methods of heat transfer performance of the material.

  5. Recent Progress in First-Principles Methods for Computing the Electronic Structure of Correlated Materials

    Directory of Open Access Journals (Sweden)

    Fredrik Nilsson

    2018-03-01

    Full Text Available Substantial progress has been achieved in the last couple of decades in computing the electronic structure of correlated materials from first principles. This progress has been driven by parallel development in theory and numerical algorithms. Theoretical development in combining ab initio approaches and many-body methods is particularly promising. A crucial role is also played by a systematic method for deriving a low-energy model, which bridges the gap between real and model systems. In this article, an overview is given tracing the development from the LDA+U to the latest progress in combining the G W method and (extended dynamical mean-field theory ( G W +EDMFT. The emphasis is on conceptual and theoretical aspects rather than technical ones.

  6. Using virtualization to protect the proprietary material science applications in volunteer computing

    Directory of Open Access Journals (Sweden)

    Khrapov Nikolay P.

    2018-04-01

    Full Text Available USPEX is a world-leading software for computational material design. In essence, USPEX splits simulation into a large number of workunits that can be processed independently. This scheme ideally fits the desktop grid architecture. Workunit processing is done by a simulation package aimed at energy minimization. Many of such packages are proprietary and should be protected from unauthorized access when running on a volunteer PC. In this paper we present an original approach based on virtualization. In a nutshell, the proprietary code and input files are stored in an encrypted folder and run inside a virtual machine image that is also password protected. The paper describes this approach in detail and discusses its application in USPEX@home volunteer project.

  7. Laser powder bed fusion additive manufacturing of metals; physics, computational, and materials challenges

    Energy Technology Data Exchange (ETDEWEB)

    King, W. E., E-mail: weking@llnl.gov [Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Anderson, A. T.; Ferencz, R. M.; Hodge, N. E.; Khairallah, S. A. [Engineering Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Kamath, C. [Computation Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Rubenchik, A. M. [NIF and Photon Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2015-12-15

    The production of metal parts via laser powder bed fusion additive manufacturing is growing exponentially. However, the transition of this technology from production of prototypes to production of critical parts is hindered by a lack of confidence in the quality of the part. Confidence can be established via a fundamental understanding of the physics of the process. It is generally accepted that this understanding will be increasingly achieved through modeling and simulation. However, there are significant physics, computational, and materials challenges stemming from the broad range of length and time scales and temperature ranges associated with the process. In this paper, we review the current state of the art and describe the challenges that need to be met to achieve the desired fundamental understanding of the physics of the process.

  8. Emerging materials and devices in spintronic integrated circuits for energy-smart mobile computing and connectivity

    International Nuclear Information System (INIS)

    Kang, S.H.; Lee, K.

    2013-01-01

    A spintronic integrated circuit (IC) is made of a combination of a semiconductor IC and a dense array of nanometer-scale magnetic tunnel junctions. This emerging field is of growing scientific and engineering interest, owing to its potential to bring disruptive device innovation to the world of electronics. This technology is currently being pursued not only for scalable non-volatile spin-transfer-torque magnetoresistive random access memory, but also for various forms of non-volatile logic (Spin-Logic). This paper reviews recent advances in spintronic IC. Key discoveries and breakthroughs in materials and devices are highlighted in light of the broader perspective of their application in low-energy mobile computing and connectivity systems, which have emerged as leading drivers for the prevailing electronics ecosystem

  9. Laser powder bed fusion additive manufacturing of metals; physics, computational, and materials challenges

    International Nuclear Information System (INIS)

    King, W. E.; Anderson, A. T.; Ferencz, R. M.; Hodge, N. E.; Khairallah, S. A.; Kamath, C.; Rubenchik, A. M.

    2015-01-01

    The production of metal parts via laser powder bed fusion additive manufacturing is growing exponentially. However, the transition of this technology from production of prototypes to production of critical parts is hindered by a lack of confidence in the quality of the part. Confidence can be established via a fundamental understanding of the physics of the process. It is generally accepted that this understanding will be increasingly achieved through modeling and simulation. However, there are significant physics, computational, and materials challenges stemming from the broad range of length and time scales and temperature ranges associated with the process. In this paper, we review the current state of the art and describe the challenges that need to be met to achieve the desired fundamental understanding of the physics of the process

  10. Logic computation in phase change materials by threshold and memory switching.

    Science.gov (United States)

    Cassinerio, M; Ciocchini, N; Ielmini, D

    2013-11-06

    Memristors, namely hysteretic devices capable of changing their resistance in response to applied electrical stimuli, may provide new opportunities for future memory and computation, thanks to their scalable size, low switching energy and nonvolatile nature. We have developed a functionally complete set of logic functions including NOR, NAND and NOT gates, each utilizing a single phase-change memristor (PCM) where resistance switching is due to the phase transformation of an active chalcogenide material. The logic operations are enabled by the high functionality of nanoscale phase change, featuring voltage comparison, additive crystallization and pulse-induced amorphization. The nonvolatile nature of memristive states provides the basis for developing reconfigurable hybrid logic/memory circuits featuring low-power and high-speed switching. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Laser powder bed fusion additive manufacturing of metals; physics, computational, and materials challenges

    Science.gov (United States)

    King, W. E.; Anderson, A. T.; Ferencz, R. M.; Hodge, N. E.; Kamath, C.; Khairallah, S. A.; Rubenchik, A. M.

    2015-12-01

    The production of metal parts via laser powder bed fusion additive manufacturing is growing exponentially. However, the transition of this technology from production of prototypes to production of critical parts is hindered by a lack of confidence in the quality of the part. Confidence can be established via a fundamental understanding of the physics of the process. It is generally accepted that this understanding will be increasingly achieved through modeling and simulation. However, there are significant physics, computational, and materials challenges stemming from the broad range of length and time scales and temperature ranges associated with the process. In this paper, we review the current state of the art and describe the challenges that need to be met to achieve the desired fundamental understanding of the physics of the process.

  12. Demonstration of a computer model for residual radioactive material guidelines, RESRAD

    International Nuclear Information System (INIS)

    Yu, C.; Yuan, Y.C.; Zielen, A.J.; Wallo, A. III

    1989-01-01

    A computer model was developed to calculate residual radioactive material guidelines for the US Department of Energy (DOE). This model, called RESRAD, can be run on IBM or IBM-compatible microcomputer. Seven potential exposure pathways from contaminated soil are analyzed, including external radiation exposure and internal radiation exposure from inhalation and food digestion. The RESRAD code has been applied to several DOE sites to derive soil cleanup guidelines. The experience gained indicates that a comprehensive set of site-specific hydrogeologic and geochemical input parameters must be used for a realistic pathway analysis. The RESRAD code is a useful tool; it is easy to run and very user-friendly. 6 refs., 12 figs

  13. On the role of solidification modelling in Integrated Computational Materials Engineering “ICME”

    International Nuclear Information System (INIS)

    Schmitz, G J; Böttger, B; Apel, M

    2016-01-01

    Solidification during casting processes marks the starting point of the history of almost any component or product. Integrated Computational Materials Engineering (ICME) [1-4] recognizes the importance of further tracking the history of microstructure evolution along the subsequent process chain. Solidification during joining processes in general happens quite late during production, where the parts to be joined already have experienced a number of processing steps which affected their microstructure. Reliable modelling of melting and dissolution of these microstructures represents a key issue before eventually modelling ‘re’-solidification e.g. during welding or soldering. Some instructive examples of microstructure evolution during a joining process obtained on the basis of synthetic and simulated initial microstructures of an Al-Cu binary model system are discussed. (paper)

  14. Using virtualization to protect the proprietary material science applications in volunteer computing

    Science.gov (United States)

    Khrapov, Nikolay P.; Rozen, Valery V.; Samtsevich, Artem I.; Posypkin, Mikhail A.; Sukhomlin, Vladimir A.; Oganov, Artem R.

    2018-04-01

    USPEX is a world-leading software for computational material design. In essence, USPEX splits simulation into a large number of workunits that can be processed independently. This scheme ideally fits the desktop grid architecture. Workunit processing is done by a simulation package aimed at energy minimization. Many of such packages are proprietary and should be protected from unauthorized access when running on a volunteer PC. In this paper we present an original approach based on virtualization. In a nutshell, the proprietary code and input files are stored in an encrypted folder and run inside a virtual machine image that is also password protected. The paper describes this approach in detail and discusses its application in USPEX@home volunteer project.

  15. Children as Educational Computer Game Designers: An Exploratory Study

    Science.gov (United States)

    Baytak, Ahmet; Land, Susan M.; Smith, Brian K.

    2011-01-01

    This study investigated how children designed computer games as artifacts that reflected their understanding of nutrition. Ten 5th grade students were asked to design computer games with the software "Game Maker" for the purpose of teaching 1st graders about nutrition. The results from the case study show that students were able to…

  16. Computational investigation and synthesis of a sol-gel imprinted material for sensing application of some biologically active molecules

    Energy Technology Data Exchange (ETDEWEB)

    Atta, Nada F., E-mail: Nada_fah1@yahoo.com [Department of Chemistry, Faculty of Science, University of Cairo, Post Code 12613, Giza (Egypt); Hamed, Maher M.; Abdel-Mageed, Ali M. [Department of Chemistry, Faculty of Science, University of Cairo, Post Code 12613, Giza (Egypt)

    2010-05-14

    A hybrid sol-gel material was molecularly imprinted with a group of neurotransmitters. Imprinted material is a sol-gel thin film that is spin coated on the surface of a glassy carbon electrode. Imprinted films were characterized electrochemically using cyclic voltammetry (CV) and the encapsulated molecules were extracted from the films and complementary molecular cavities are formed that enable their rebind. The films were tested in their corresponding template solutions for rebinding using square wave voltammetry (SWV). Computational approach for exploring the primary intermolecular forces between templates and hydrolyzed form of the precursor monomer, tetraethylorthosilicate (TEOS), were carried out using Hartree-Fock method (HF). Interaction energy values were computed for each adduct formed between a monomer and a template. Analysis of the optimized conformations of various adducts could explain the mode of interaction between the templates and the monomer units. We found that interaction via the amino group is the common mode among the studied compounds and the results are in good agreement with the electrochemical measurements.

  17. Study of biocompatible and biological materials

    CERN Document Server

    Pecheva, Emilia

    2017-01-01

    The book gives an overview on biomineralization, biological, biocompatible and biomimetic materials. It reveals the use of biomaterials alone or in composites, how their performance can be improved by tailoring their surface properties by external factors and how standard surface modification techniques can be applied in the area of biomaterials to beneficially influence their growth on surfaces.

  18. Computation of thermodynamic equilibria of nuclear materials in multi-physics codes

    International Nuclear Information System (INIS)

    Piro, M.H.; Lewis, B.J.; Thompson, W.T.; Simunovic, S.; Besmann, T.M.

    2011-01-01

    A new equilibrium thermodynamic solver is being developed with the primary impetus of direct integration into nuclear fuel performance and safety codes to provide improved predictions of fuel behavior. This solver is intended to provide boundary conditions and material properties for continuum transport calculations. There are several legitimate concerns with the use of existing commercial thermodynamic codes: 1) licensing entanglements associated with code distribution, 2) computational performance, and 3) limited capabilities of handling large multi-component systems of interest to the nuclear industry. The development of this solver is specifically aimed at addressing these concerns. In support of this goal, a new numerical algorithm for computing chemical equilibria is presented which is not based on the traditional steepest descent method or 'Gibbs energy minimization' technique. This new approach exploits fundamental principles of equilibrium thermodynamics, which simplifies the optimization equations. The chemical potentials of all species and phases in the system are constrained by the system chemical potentials, and the objective is to minimize the residuals of the mass balance equations. Several numerical advantages are achieved through this simplification, as described in this paper. (author)

  19. Computational simulation of the creep-rupture process in filamentary composite materials

    Science.gov (United States)

    Slattery, Kerry T.; Hackett, Robert M.

    1991-01-01

    A computational simulation of the internal damage accumulation which causes the creep-rupture phenomenon in filamentary composite materials is developed. The creep-rupture process involves complex interactions between several damage mechanisms. A statistically-based computational simulation using a time-differencing approach is employed to model these progressive interactions. The finite element method is used to calculate the internal stresses. The fibers are modeled as a series of bar elements which are connected transversely by matrix elements. Flaws are distributed randomly throughout the elements in the model. Load is applied, and the properties of the individual elements are updated at the end of each time step as a function of the stress history. The simulation is continued until failure occurs. Several cases, with different initial flaw dispersions, are run to establish a statistical distribution of the time-to-failure. The calculations are performed on a supercomputer. The simulation results compare favorably with the results of creep-rupture experiments conducted at the Lawrence Livermore National Laboratory.

  20. Multiscale modeling, coarse-graining and shock wave computer simulationsin materials science

    Directory of Open Access Journals (Sweden)

    Martin O. Steinhauser

    2017-12-01

    Full Text Available My intention in this review article is to briefly discuss several major topics of presentdaycomputational materials science in order to show their importance for state-of-the-art materialsmodeling and computer simulation. The topics I discuss are multiscale modeling approaches forhierarchical systems such as biological macromolecules and related coarse-graining techniques, whichprovide an effcient means to investigate systems on the mesoscale, and shock wave physics whichhas many important and interesting multi- and interdisciplinary applications in research areas wherephysics, biology, chemistry, computer science, medicine and even engineering meet. In fact, recently,as a new emerging field, the use of coarse-grained approaches for the simulation of biologicalmacromolecules such as lipids and bilayer membranes and the investigation of their interaction withshock waves has become very popular. This emerging area of research may contribute not only toan improved understanding of the microscopic details of molecular self-assembly but may also leadto enhanced medical tumor treatments which are based on the destructive effects of High IntensityFocused Ultrasound (HIFU or shock waves when interacting with biological cells and tissue; theseare treatments which have been used in medicine for many years, but which are not well understoodfrom a fundamental physical point of view.

  1. TAOI B- Computational Microstructural Optimization Design Tool for High Temperature Structural Materials

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Rajiv [Univ. Of North Texas, Denton, TX (United States); Charit, Indrajit [Univ. of Idaho, Moscow, ID (United States)

    2015-02-28

    The objectives of this research were two-fold: (a) develop a methodology for microstructural optimization of alloys - genetic algorithm approach for alloy microstructural optimization using theoretical models based on fundamental micro-mechanisms, and (b) develop a new computationally designed Ni-Cr alloy for coal-fired power plant applications. The broader outcome of these objectives is expected to be creation of an integrated approach for ‘structural materials by microstructural design’. Three alloy systems were considered for computational optimization and validation, (i) Ni-20Cr (wt.%) base alloy using only solid solution strengthening, (ii) nano-Y2O3 containing Ni-20Cr-1.2Y2O3 (wt.%) alloy for dispersion strengthening and (iii) a sub-micron Al2O3 for composite strengthening, Ni-20Cr-1.2Y2O3-5.0Al2O3 (wt.%). The specimens were synthesized by mechanical alloying and consolidated using spark plasma sintering. Detailed microstructural characterization was done along with initial mechanical properties to validate the computational prediction. A key target property is to have creep rate of 1x10-9 s-1 at 100 MPa and 800oC. The initial results were quite promising and require additional quantification of strengthening contributions from dislocation-particle attractive interaction and load transfer. The observed creep rate was in order of 10-9 s-1 for longer time creep test of Ni-20Cr -1.2Y2O3-5Al2O3, lending support to the overall approach pursued in this project.

  2. Seventeenth Workshop on Computer Simulation Studies in Condensed-Matter Physics

    CERN Document Server

    Landau, David P; Schütler, Heinz-Bernd; Computer Simulation Studies in Condensed-Matter Physics XVI

    2006-01-01

    This status report features the most recent developments in the field, spanning a wide range of topical areas in the computer simulation of condensed matter/materials physics. Both established and new topics are included, ranging from the statistical mechanics of classical magnetic spin models to electronic structure calculations, quantum simulations, and simulations of soft condensed matter. The book presents new physical results as well as novel methods of simulation and data analysis. Highlights of this volume include various aspects of non-equilibrium statistical mechanics, studies of properties of real materials using both classical model simulations and electronic structure calculations, and the use of computer simulations in teaching.

  3. Replacement of traditional lectures with computer-based tutorials: a case study

    Directory of Open Access Journals (Sweden)

    Derek Lavelle

    1996-12-01

    Full Text Available This paper reports on a pilot project with a group of 60 second-year undergraduates studying the use of standard forms of contract in the construction industry. The project entailed the replacement of two of a series of nine scheduled lectures with a computer-based tutorial. The two main aims of the project were to test the viability of converting existing lecture material into computer-based material on an in-house production basis, and to obtain feedback from the student cohort on their behavioural response to the change in media. The effect on student performance was not measured at this stage of development.

  4. Fluorescent x-ray computed tomography to visualize specific material distribution

    Science.gov (United States)

    Takeda, Tohoru; Yuasa, Tetsuya; Hoshino, Atsunori; Akiba, Masahiro; Uchida, Akira; Kazama, Masahiro; Hyodo, Kazuyuki; Dilmanian, F. Avraham; Akatsuka, Takao; Itai, Yuji

    1997-10-01

    Fluorescent x-ray computed tomography (FXCT) is being developed to detect non-radioactive contrast materials in living specimens. The FXCT systems consists of a silicon channel cut monochromator, an x-ray slit and a collimator for detection, a scanning table for the target organ and an x-ray detector for fluorescent x-ray and transmission x-ray. To reduce Compton scattering overlapped on the K(alpha) line, incident monochromatic x-ray was set at 37 keV. At 37 keV Monte Carlo simulation showed almost complete separation between Compton scattering and the K(alpha) line. Actual experiments revealed small contamination of Compton scattering on the K(alpha) line. A clear FXCT image of a phantom was obtained. Using this system the minimal detectable dose of iodine was 30 ng in a volume of 1 mm3, and a linear relationship was demonstrated between photon counts of fluorescent x-rays and the concentration of iodine contrast material. The use of high incident x-ray energy allows an increase in the signal to noise ratio by reducing the Compton scattering on the K(alpha) line.

  5. Gypsum plasterboards enhanced with phase change materials: A fire safety assessment using experimental and computational techniques

    Directory of Open Access Journals (Sweden)

    Kolaitis Dionysios I.

    2013-11-01

    Full Text Available Phase Change Materials (PCM can be used for thermal energy storage, aiming to enhance building energy efficiency. Recently, gypsum plasterboards with incorporated paraffin-based PCM blends have become commercially available. In the high temperature environment developed during a fire, the paraffins, which exhibit relatively low boiling points, may evaporate and, escaping through the gypsum plasterboard's porous structure, emerge to the fire region, where they may ignite, thus adversely affecting the fire resistance characteristics of the building. Aiming to assess the fire safety behaviour of such building materials, an extensive experimental and computational analysis is performed. The fire behaviour and the main thermo-physical physical properties of PCM-enhanced gypsum plasterboards are investigated, using a variety of standard tests and devices (Scanning Electron Microscopy, Thermo Gravimetric Analysis, Cone Calorimeter. The obtained results are used to develop a dedicated numerical model, which is implemented in a CFD code. CFD simulations are validated using measurements obtained in a cone calorimeter. In addition, the CFD code is used to simulate an ISO 9705 room exposed to fire conditions, demonstrating that PCM addition may indeed adversely affect the fire safety of a gypsum plasterboard clad building.

  6. Computer aided process planning system based on workflow technology and integrated bill of material tree

    Institute of Scientific and Technical Information of China (English)

    LU Chun-guang; MENG Li-li

    2006-01-01

    It is extremely important for procedure of process design and management of process data for product life cycle in Computer Aided Process Planning (CAPP) system,but there are many shortcomings with traditional CAPP system in these respects.To solve these questions,application of workflow technology in CAPP system based on web-integrated Bill of Material (BOM) tree is discussed,and a concept of integrated BOM tree was brought forward.Taking integrated BOM as the thread,CAPP systematic technological process is analyzed.The function,system architecture,and implementation mechanism of CAPP system based on Browser/Server and Customer/Server model are expatiated.Based on it,the key technologies of workflow management device were analyzed.Eventually,the implementation mechanism of integrated BOM tree was analyzed from viewpoints of material information encoding,organization node design of integrated BOM tree,transformation from Engineering BOM (EBOM)to Process BOM (PBOM),and the programming implementation technology.

  7. Computer Simulation of Material Flow in Warm-forming Bimetallic Components

    Science.gov (United States)

    Kong, T. F.; Chan, L. C.; Lee, T. C.

    2007-05-01

    Bimetallic components take advantage of two different metals or alloys so that their applicable performance, weight and cost can be optimized. However, since each material has its own flow properties and mechanical behaviour, heterogeneous material flows will occur during the bimetal forming process. Those controls of process parameters are relatively more complicated than forming single metals. Most previous studies in bimetal forming have focused mainly on cold forming, and less relevant information about the warm forming has been provided. Indeed, changes of temperature and heat transfer between two materials are the significant factors which can highly influence the success of the process. Therefore, this paper presents a study of the material flow in warm-forming bimetallic components using finite-element (FE) simulation in order to determine the suitable process parameters for attaining the complete die filling. A watch-case-like component made of stainless steel (AISI-316L) and aluminium alloy (AL-6063) was used as the example. The warm-forming processes were simulated with the punch speeds V of 40, 80, and 120 mm/s and the initial temperatures of the stainless steel TiSS of 625, 675, 725, 775, 825, 875, 925, 975, and 1025 °C. The results showed that the AL-6063 flowed faster than the AISI-316L and so the incomplete die filling was only found in the AISI-316L region. A higher TiSS was recommended to avoid incomplete die filling. The reduction of V is also suggested because this can save the forming energy and prevent the damage of tooling. Eventually, with the experimental verification, the results from the simulation were in agreement with those of the experiments. On the basis of the results of this study, engineers can gain a better understanding of the material flow in warm-forming bimetallic components, and be able to determine more efficiently the punch speed and initial material temperature for the process.

  8. Design and Development Computer-Based E-Learning Teaching Material for Improving Mathematical Understanding Ability and Spatial Sense of Junior High School Students

    Science.gov (United States)

    Nurjanah; Dahlan, J. A.; Wibisono, Y.

    2017-02-01

    This paper aims to make a design and development computer-based e-learning teaching material for improving mathematical understanding ability and spatial sense of junior high school students. Furthermore, the particular aims are (1) getting teaching material design, evaluation model, and intrument to measure mathematical understanding ability and spatial sense of junior high school students; (2) conducting trials computer-based e-learning teaching material model, asessment, and instrument to develop mathematical understanding ability and spatial sense of junior high school students; (3) completing teaching material models of computer-based e-learning, assessment, and develop mathematical understanding ability and spatial sense of junior high school students; (4) resulting research product is teaching materials of computer-based e-learning. Furthermore, the product is an interactive learning disc. The research method is used of this study is developmental research which is conducted by thought experiment and instruction experiment. The result showed that teaching materials could be used very well. This is based on the validation of computer-based e-learning teaching materials, which is validated by 5 multimedia experts. The judgement result of face and content validity of 5 validator shows that the same judgement result to the face and content validity of each item test of mathematical understanding ability and spatial sense. The reliability test of mathematical understanding ability and spatial sense are 0,929 and 0,939. This reliability test is very high. While the validity of both tests have a high and very high criteria.

  9. Spring 2005 Industry Study. Strategic Materials

    Science.gov (United States)

    2005-01-01

    older, increasingly obsolescent, technologies are marshaled to finance the newly produced capital assets that embody cutting-edge technologies. This...Research Laboratory, Weapons and Materials Research Center. Presented at ARL, Aberdeen, MD. March 17, 2005. Ashley, Steven. “ Alchemy of a...and London: Westview Press, 1985 Butkiewicz, James. “Reconstruction Finance Corporation.” EH.Net Encyclopedia. http://www.eh.net/encyclopedia

  10. Computational time-resolved and resonant x-ray scattering of strongly correlated materials

    Energy Technology Data Exchange (ETDEWEB)

    Bansil, Arun [Northeastern Univ., Boston, MA (United States)

    2016-11-09

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source, literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspects of this grand challenge of x-ray science. In particular, our Collaborative Research Team (CRT) focused on developing viable computational schemes for modeling x-ray scattering and photoemission spectra of strongly correlated materials in the time-domain. The vast arsenal of formal/numerical techniques and approaches encompassed by the members of our CRT were brought to bear through appropriate generalizations and extensions to model the pumped state and the dynamics of this non-equilibrium state, and how it can be probed via x-ray absorption (XAS), emission (XES), resonant and non-resonant x-ray scattering, and photoemission processes. We explored the conceptual connections between the time-domain problems and other second-order spectroscopies, such as resonant inelastic x-ray scattering (RIXS) because RIXS may be effectively thought of as a pump-probe experiment in which the incoming photon acts as the pump, and the fluorescent decay is the probe. Alternatively, when the core-valence interactions are strong, one can view K-edge RIXS for example, as the dynamic response of the material to the transient presence of a strong core-hole potential. Unlike an actual pump-probe experiment, here there is no mechanism for adjusting the time-delay between the pump and the probe. However, the core hole

  11. Computational Thermodynamics of Materials Zi-Kui Liu and Yi Wang

    Energy Technology Data Exchange (ETDEWEB)

    Devanathan, Ram

    2017-02-01

    This authoritative volume introduces the reader to computational thermodynamics and the use of this approach to the design of material properties by tailoring the chemical composition. The text covers applications of this approach, introduces the relevant computational codes, and offers exercises at the end of each chapter. The book has nine chapters and two appendices that provide background material on computer codes. Chapter 1 covers the first and second laws of thermodynamics, introduces the spinodal as the limit of stability, and presents the Gibbs-Duhem equation. Chapter 2 focuses on the Gibbs energy function. Starting with a homogeneous system with a single phase, the authors proceed to phases with variable compositions, and polymer blends. The discussion includes the contributions of external electric and magnetic fields to the Gibbs energy. Chapter 3 deals with phase equilibria in heterogeneous systems, the Gibbs phase rule, and phase diagrams. Chapter 4 briefly covers experimental measurements of thermodynamic properties used as input for thermodynamic modeling by Calculation of Phase Diagrams (CALPHAD). Chapter 5 discusses the use of density functional theory to obtain thermochemical data and fill gaps where experimental data is missing. The reader is introduced to the Vienna Ab Initio Simulation Package (VASP) for density functional theory and the YPHON code for phonon calculations. Chapter 6 introduces the modeling of Gibbs energy of phases with the CALPHAD method. Chapter 7 deals with chemical reactions and the Ellingham diagram for metal-oxide systems and presents the calculation of the maximum reaction rate from equilibrium thermodynamics. Chapter 8 is devoted to electrochemical reactions and Pourbaix diagrams with application examples. Chapter 9 concludes this volume with the application of a model of multiple microstates to Ce and Fe3Pt. CALPHAD modeling is briefly discussed in the context of genomics of materials. The book introduces basic

  12. Computed phase equilibria for burnable neutron absorbing materials for advanced pressurized heavy water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Corcoran, E.C. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada)], E-mail: emily.corcoran@rmc.ca; Lewis, B.J.; Thompson, W.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada); Hood, J. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada); Akbari, F.; He, Z. [Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ont., K0J 1J0 (Canada); Reid, P. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada)

    2009-03-31

    Burnable neutron absorbing materials are expected to be an integral part of the new fuel design for the Advanced CANDU [CANDU is as a registered trademark of Atomic Energy of Canada Limited.] Reactor. The neutron absorbing material is composed of gadolinia and dysprosia dissolved in an inert cubic-fluorite yttria-stabilized zirconia matrix. A thermodynamic model based on Gibbs energy minimization has been created to provide estimated phase equilibria as a function of composition and temperature. This work includes some supporting experimental studies involving X-ray diffraction.

  13. Study of Nuclear Environment and Material Strategy

    International Nuclear Information System (INIS)

    Kamei, Takashi

    2011-01-01

    Progress of global warming requires us to establish a low-carbon society. Carbon-dioxide (CO 2 ) is emitted from two major sectors in the world. The largest CO 2 emitting sector is power sector having 46 % of the world share. Nuclear power has an important role because it does not emit CO 2 while it produces electricity. The second largest sector is transportation and has about 23 % of the world share. 73 % of transportation is land-transportation, that is to say automobile. Therefore, lots of motor-car companies are expressing their vision to supply electric vehicle (EV) or hybrid vehicle (HV) in these few years. In order to manufacture EV and HV, rare-earth materials such as neodymium (Nd) and dysprosium (Dy) are necessary. EV and HV are driven by an electric motor using permanent magnet. Nd is used to improve torque of permanent magnet. Dy is used as supplement for the case of HV in order to enhance thermal resistance because electric motor is exposed to high temperature circumference with combustion engine. 97 % of world supply of rare-earth production is shared by China. The reduction of exportation amount of rare-earth from China to Japan have brought a significant impact on Japan's industries especially for motor-car companies, which are going to supply EV and HV. Japan is going to develop new rare-earth mines outside of China such as in Vietnam. The most important problem relating to rare-earth mining is 'thorium'. The popular minerals containing rare-earth are monazite, bastnasite and so on. Thorium is mostly included in the same minerals. Therefore, thorium is separated whenever rare-earth is refined. Thorium separated in China can be stored for future usage as nuclear fuel. Though thorium began to be considered also in a working group of Atomic Energy Society of Japan since 2010, it is not clear when thorium starts to be used and how much amount of thorium will be consumed. It is estimated that consumption of thorium will be smaller than the production

  14. First principles studies of multiferroic materials

    International Nuclear Information System (INIS)

    Picozzi, Silvia; Ederer, Claude

    2009-01-01

    Multiferroics, materials where spontaneous long-range magnetic and dipolar orders coexist, represent an attractive class of compounds, which combine rich and fascinating fundamental physics with a technologically appealing potential for applications in the general area of spintronics. Ab initio calculations have significantly contributed to recent progress in this area, by elucidating different mechanisms for multiferroicity and providing essential information on various compounds where these effects are manifestly at play. In particular, here we present examples of density-functional theory investigations for two main classes of materials: (a) multiferroics where ferroelectricity is driven by hybridization or purely structural effects, with BiFeO 3 as the prototype material, and (b) multiferroics where ferroelectricity is driven by correlation effects and is strongly linked to electronic degrees of freedom such as spin-, charge-, or orbital-ordering, with rare-earth manganites as prototypes. As for the first class of multiferroics, first principles calculations are shown to provide an accurate qualitative and quantitative description of the physics in BiFeO 3 , ranging from the prediction of large ferroelectric polarization and weak ferromagnetism, over the effect of epitaxial strain, to the identification of possible scenarios for coupling between ferroelectric and magnetic order. For the second class of multiferroics, ab initio calculations have shown that, in those cases where spin-ordering breaks inversion symmetry (e.g. in antiferromagnetic E-type HoMnO 3 ), the magnetically induced ferroelectric polarization can be as large as a few μC cm -2 . The examples presented point the way to several possible avenues for future research: on the technological side, first principles simulations can contribute to a rational materials design, aimed at identifying spintronic materials that exhibit ferromagnetism and ferroelectricity at or above room temperature. On the

  15. Computational studies of layered trititanates with magnetic doping

    Science.gov (United States)

    Heath, Caleb; Barraza-Lopez, Salvador; Tian, Z. Ryan

    Layered titanate nanostructures are of great interest due to their ease of synthesis, modifiability, and variety in application. A profusion of experimental literature exists for these compounds but existing computational work has been limited in both quantity and scope. We examine hydrogen trititanate (H2Ti3O7) with and without magnetic substitutional doping. Band structure, elastic properties, material stability, and magnetic properties of these titanates will be discussed. This research is supported by the Arkansas High Performance Computing Center which is funded through multiple National Science Foundation Grants and the Arkansas Economic Development Commission.

  16. NASA Computational Case Study: The Flight of Friendship 7

    Science.gov (United States)

    Simpson, David G.

    2012-01-01

    In this case study, we learn how to compute the position of an Earth-orbiting spacecraft as a function of time. As an exercise, we compute the position of John Glenn's Mercury spacecraft Friendship 7 as it orbited the Earth during the third flight of NASA's Mercury program.

  17. Studies in Mathematics, Volume 22. Studies in Computer Science.

    Science.gov (United States)

    Pollack, Seymour V., Ed.

    The nine articles in this collection were selected because they represent concerns central to computer science, emphasize topics of particular interest to mathematicians, and underscore the wide range of areas deeply and continually affected by computer science. The contents consist of: "Introduction" (S. V. Pollack), "The…

  18. Study of check image using computed radiography

    International Nuclear Information System (INIS)

    Sato, Hiroshi

    2002-01-01

    There are two image forming methods both a check image and a portal image in the linacogram. It has been established the image forming method in the check image using computed radiography (CR). On the other hand, it is not established the image forming method in the portal image using CR yet. Usually, in the electric portal imaging device (EPID) is mainly used just before radiotherapy start. The usefulness of the portal image forming method by CR using in place of EPID is possible to confirm the precision for determining to specific position at the irradiate part and to the irradiate method for the human organs. There are some technical problems that, since in the early time, the linac graphy (LG) image have low resolution power. In order to improve to the resolution power in LG image, CR image technologies have been introduced to the check image forming method. Heavy metallic sheet (HMS) is used to the front side of CR-IP cassette, and high contactness sponge is used to the back side of the cassette. Improved contactness between HMS and imaging plate (IP) by means of the high contactness sponge contributed to improve the resolution power in the check images. A lot of paper which is connected with these information have been reported. Imaging plate ST-III should be used to maintain high sensitivity in the check film image forming method. The same image forming method in the check image established by CR has been introduced into the portal image forming method in order to improve the resolution power. However, as a result, it couldn't acquired high resolution image forming in the portal images because of the combination of ST-III and radiotherapy dose. After several trials, it has been recognized that HR-V imaging plate for mammography is the most useful application to maintain high resolution power in the portal images. Also, it is possible to modify the image quality by changing GS parameter which is one of image processing parameters in CR. Furthermore, in case

  19. Combined experimental and computational modelling studies of the solubility of nickel in strontium titanate

    NARCIS (Netherlands)

    Beale, A.M.; Paul, M.; Sankar, G.; Oldman, R.J.; Catlow, R.A.; French, S.; Fowles, M.

    2009-01-01

    A combination of X-ray techniques and atomistic computational modelling has been used to study the solubility of Ni in SrTiO3 in relation to the application of this material for the catalytic partial oxidation of methane. The experiments have demonstrated that low temperature, hydrothermal synthesis

  20. Studies of bulk materials for thermoelectric cooling

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, J W; Nolas, G S; Volckmann, E H

    1997-07-01

    The authors discuss ongoing work in three areas of thermoelectric materials research: (1) broad band semiconductors featuring anion networks, (2) filled skutterudites, and (3) polycrystalline Bi-Sb alloys. Key results include: a preliminary evaluation of a previously untested ternary semiconductor, KSnSb; the first reported data in which Sn is used as a charge compensator in filled antimonide skutterudites; the finding that Sn doping does not effect polycrystalline Bi{sub 1{minus}x}Sb{sub x} as it does single crystal samples.

  1. GPU-based parallel computing in real-time modeling of atmospheric transport and diffusion of radioactive material

    International Nuclear Information System (INIS)

    Santos, Marcelo C. dos; Pereira, Claudio M.N.A.; Schirru, Roberto; Pinheiro, André; Coordenacao de Pos-Graduacao e Pesquisa de Engenharia

    2017-01-01

    Atmospheric radionuclide dispersion systems (ARDS) are essential mechanisms to predict the consequences of unexpected radioactive releases from nuclear power plants. Considering, that during an eventuality of an accident with a radioactive material release, an accurate forecast is vital to guide the evacuation plan of the possible affected areas. However, in order to predict the dispersion of the radioactive material and its impact on the environment, the model must process information about source term (radioactive materials released, activities and location), weather condition (wind, humidity and precipitation) and geographical characteristics (topography). Furthermore, ARDS is basically composed of 4 main modules: Source Term, Wind Field, Plume Dispersion and Doses Calculations. The Wind Field and Plume Dispersion modules are the ones that require a high computational performance to achieve accurate results within an acceptable time. Taking this into account, this work focuses on the development of a GPU-based parallel Plume Dispersion module, focusing on the radionuclide transport and diffusion calculations, which use a given wind field and a released source term as parameters. The program is being developed using the C ++ programming language, allied with CUDA libraries. In comparative case study between a parallel and sequential version of the slower function of the Plume Dispersion module, a speedup of 11.63 times could be observed. (author)

  2. GPU-based parallel computing in real-time modeling of atmospheric transport and diffusion of radioactive material

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Marcelo C. dos; Pereira, Claudio M.N.A.; Schirru, Roberto; Pinheiro, André, E-mail: jovitamarcelo@gmail.com, E-mail: cmnap@ien.gov.br, E-mail: schirru@lmp.ufrj.br, E-mail: apinheiro99@gmail.com [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear

    2017-07-01

    Atmospheric radionuclide dispersion systems (ARDS) are essential mechanisms to predict the consequences of unexpected radioactive releases from nuclear power plants. Considering, that during an eventuality of an accident with a radioactive material release, an accurate forecast is vital to guide the evacuation plan of the possible affected areas. However, in order to predict the dispersion of the radioactive material and its impact on the environment, the model must process information about source term (radioactive materials released, activities and location), weather condition (wind, humidity and precipitation) and geographical characteristics (topography). Furthermore, ARDS is basically composed of 4 main modules: Source Term, Wind Field, Plume Dispersion and Doses Calculations. The Wind Field and Plume Dispersion modules are the ones that require a high computational performance to achieve accurate results within an acceptable time. Taking this into account, this work focuses on the development of a GPU-based parallel Plume Dispersion module, focusing on the radionuclide transport and diffusion calculations, which use a given wind field and a released source term as parameters. The program is being developed using the C ++ programming language, allied with CUDA libraries. In comparative case study between a parallel and sequential version of the slower function of the Plume Dispersion module, a speedup of 11.63 times could be observed. (author)

  3. Development of a computer model using the EGS4 simulation code to calculate scattered X-rays through some materials

    International Nuclear Information System (INIS)

    Al-Ghorabie, F.H.H.

    2003-01-01

    In this paper a computer model based on the use of the well-known Monte Carlo simulation code EGS4 was developed to simulate the scattering of polyenergetic X-ray beams through some materials. These materials are: lucite, polyethylene, polypropylene and aluminium. In particular, the ratio of the scattered to total X-ray fluence (scatter fraction) has been calculated for X-ray beams in the energy region 30-120 keV. In addition scatter fractions have been determined experimentally using a polyenergetic superficial X-ray unit. Comparison of the measured and the calculated results has been performed. The Monte Carlo calculations have also been carried out for water, bakelite and bone to examine the dependence of scatter fraction on the density of the scatterer. Good agreement (estimated statistical error < 5%) was obtained between the measured and the calculated values of the scatter fractions for materials with Z < 20 that were studied in this paper. Copyright (2003) Australasian College of Physical Scientists and Engineers in Medicine

  4. Computational Text Analysis: A More Comprehensive Approach to Determine Readability of Reading Materials

    Science.gov (United States)

    Aziz, Anealka; Fook, Chan Yuen; Alsree, Zubaida

    2010-01-01

    Reading materials are considered having high readability if readers are interested to read the materials, understand the content of the materials and able to read the materials fluently. In contrast, reading materials with low readability discourage readers from reading the materials, create difficulties for readers to understand the content of…

  5. Synthesis & Studies of New Non-Destructive Read-Out Materials for Optical Storage and Optical Switches

    National Research Council Canada - National Science Library

    Rentzepis, Peter M

    2005-01-01

    .... The optical, chemical and spectroscopic properties of this non-destructive write/read/erase computer memory material have been studied This organic storage system consists of two different molecular...

  6. Open-Source Software in Computational Research: A Case Study

    Directory of Open Access Journals (Sweden)

    Sreekanth Pannala

    2008-04-01

    Full Text Available A case study of open-source (OS development of the computational research software MFIX, used for multiphase computational fluid dynamics simulations, is presented here. The verification and validation steps required for constructing modern computational software and the advantages of OS development in those steps are discussed. The infrastructure used for enabling the OS development of MFIX is described. The impact of OS development on computational research and education in gas-solids flow, as well as the dissemination of information to other areas such as geophysical and volcanology research, is demonstrated. This study shows that the advantages of OS development were realized in the case of MFIX: verification by many users, which enhances software quality; the use of software as a means for accumulating and exchanging information; the facilitation of peer review of the results of computational research.

  7. Educational NASA Computational and Scientific Studies (enCOMPASS)

    Science.gov (United States)

    Memarsadeghi, Nargess

    2013-01-01

    Educational NASA Computational and Scientific Studies (enCOMPASS) is an educational project of NASA Goddard Space Flight Center aimed at bridging the gap between computational objectives and needs of NASA's scientific research, missions, and projects, and academia's latest advances in applied mathematics and computer science. enCOMPASS achieves this goal via bidirectional collaboration and communication between NASA and academia. Using developed NASA Computational Case Studies in university computer science/engineering and applied mathematics classes is a way of addressing NASA's goals of contributing to the Science, Technology, Education, and Math (STEM) National Objective. The enCOMPASS Web site at http://encompass.gsfc.nasa.gov provides additional information. There are currently nine enCOMPASS case studies developed in areas of earth sciences, planetary sciences, and astrophysics. Some of these case studies have been published in AIP and IEEE's Computing in Science and Engineering magazines. A few university professors have used enCOMPASS case studies in their computational classes and contributed their findings to NASA scientists. In these case studies, after introducing the science area, the specific problem, and related NASA missions, students are first asked to solve a known problem using NASA data and past approaches used and often published in a scientific/research paper. Then, after learning about the NASA application and related computational tools and approaches for solving the proposed problem, students are given a harder problem as a challenge for them to research and develop solutions for. This project provides a model for NASA scientists and engineers on one side, and university students, faculty, and researchers in computer science and applied mathematics on the other side, to learn from each other's areas of work, computational needs and solutions, and the latest advances in research and development. This innovation takes NASA science and

  8. Quantitative Study on Computer Self-Efficacy and Computer Anxiety Differences in Academic Major and Residential Status

    Science.gov (United States)

    Binkley, Zachary Wayne McClellan

    2017-01-01

    This study investigates computer self-efficacy and computer anxiety within 61 students across two academic majors, Aviation and Sports and Exercise Science, while investigating the impact residential status, age, and gender has on those two psychological constructs. The purpose of the study is to find if computer self-efficacy and computer anxiety…

  9. Influence of different luting protocols on shear bond strength of computer aided design/computer aided manufacturing resin nanoceramic material to dentin.

    Science.gov (United States)

    Poggio, Claudio; Pigozzo, Marco; Ceci, Matteo; Scribante, Andrea; Beltrami, Riccardo; Chiesa, Marco

    2016-01-01

    The purpose of this study was to evaluate the influence of three different luting protocols on shear bond strength of computer aided design/computer aided manufacturing (CAD/CAM) resin nanoceramic (RNC) material to dentin. In this in vitro study, 30 disks were milled from RNC blocks (Lava Ultimate/3M ESPE) with CAD/CAM technology. The disks were subsequently cemented to the exposed dentin of 30 recently extracted bovine permanent mandibular incisors. The specimens were randomly assigned into 3 groups of 10 teeth each. In Group 1, disks were cemented using a total-etch protocol (Scotchbond™ Universal Etchant phosphoric acid + Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 2, disks were cemented using a self-etch protocol (Scotchbond Universal Adhesive + RelyX™ Ultimate conventional resin cement); in Group 3, disks were cemented using a self-adhesive protocol (RelyX™ Unicem 2 Automix self-adhesive resin cement). All cemented specimens were placed in a universal testing machine (Instron Universal Testing Machine 3343) and submitted to a shear bond strength test to check the strength of adhesion between the two substrates, dentin, and RNC disks. Specimens were stressed at a crosshead speed of 1 mm/min. Data were analyzed with analysis of variance and post-hoc Tukey's test at a level of significance of 0.05. Post-hoc Tukey testing showed that the highest shear strength values (P adhesives) showed better shear strength values compared to self-adhesive resin cements. Furthermore, conventional resin cements used together with a self-etch adhesive reported the highest values of adhesion.

  10. Fluoride removal studies in water using natural materials : technical ...

    African Journals Online (AJOL)

    Excess fluoride in water causes health hazards to the natural environment. The removal of fluoride was attempted using natural materials such as red soil, charcoal, brick, fly-ash and serpentine. Each material was set up in a column for a known volume and the defluoridation capacities of these materials were studied with ...

  11. A computer based approach for Material, Manpower and Equipment managementin the Construction Projects

    Science.gov (United States)

    Sasidhar, Jaladanki; Muthu, D.; Venkatasubramanian, C.; Ramakrishnan, K.

    2017-07-01

    The success of any construction project will depend on efficient management of resources in a perfect manner to complete the project with a reasonable budget and time and the quality cannot be compromised. The efficient and timely procurement of material, deployment of adequate labor at correct time and mobilization of machinery lacking in time, all of them causes delay, lack of quality and finally affect the project cost. It is known factor that Project cost can be controlled by taking corrective actions on mobilization of resources at a right time. This research focuses on integration of management systems with the computer to generate the model which uses OOM data structure which decides to include automatic commodity code generation, automatic takeoff execution, intelligent purchase order generation, and components of design and schedule integration to overcome the problems of stock out. To overcome the problem in equipment management system inventory management module is suggested and the data set of equipment registration number, equipment number, description, date of purchase, manufacturer, equipment price, market value, life of equipment, production data of the equipment which includes equipment number, date, name of the job, hourly rate, insurance, depreciation cost of the equipment, taxes, storage cost, interest, oil, grease, and fuel consumption, etc. is analyzed and the decision support systems to overcome the problem arising out improper management is generated. The problem on labor is managed using scheduling, Strategic management of human resources. From the generated support systems tool, the resources are mobilized at a right time and help the project manager to finish project in time and thereby save the abnormal project cost and also provides the percentage that can be improved and also research focuses on determining the percentage of delays that are caused by lack of management of materials, manpower and machinery in different types of projects

  12. Non-von Neumann computing using plasmon particles interacting with phase change materials (Conference Presentation)

    Science.gov (United States)

    Saiki, Toshiharu

    2016-09-01

    Control of localized surface plasmon resonance (LSPR) excited on metal nanostructures has drawn attention for applications in dynamic switching of plasmonic devices. As a reversible active media for LSPR control, chalcogenide phase-change materials (PCMs) such as GeSbTe (GST) are promising for high-contrast robust plasmonic switching. Owing to the plasticity and the threshold behavior during both amorphization and crystallization of PCMs, PCM-based LSPR switching elements possess a dual functionality of memory and processing. Integration of LSPR switching elements so that they interact with each other will allow us to build non-von-Neumann computing devices. As a specific demonstration, we discuss the implementation of a cellular automata (CA) algorithm into interacting LSPR switching elements. In the model we propose, PCM cells, which can be in one of two states (amorphous and crystalline), interact with each other by being linked by a AuNR, whose LSPR peak wavelength is determined by the phase of PCM cells on the both sides. The CA program proceeds by irradiating with a light pulse train. The local rule set is defined by the temperature rise in the PCM cells induced by the LSPR of the AuNR, which is subject to the intensity and wavelength of the irradiating pulse. We also investigate the possibility of solving a problem analogous to the spin-glass problem by using a coupled dipole system, in which the individual coupling strengths can be modified to optimize the system so that the exact solution can be easily reached. For this algorithm, we propose an implementation based on an idea that coupled plasmon particles can create long-range spatial correlations, and the interaction of this with a phase-change material allows the coupling strength to be modified.

  13. A study of computer-related upper limb discomfort and computer vision syndrome.

    Science.gov (United States)

    Sen, A; Richardson, Stanley

    2007-12-01

    Personal computers are one of the commonest office tools in Malaysia today. Their usage, even for three hours per day, leads to a health risk of developing Occupational Overuse Syndrome (OOS), Computer Vision Syndrome (CVS), low back pain, tension headaches and psychosocial stress. The study was conducted to investigate how a multiethnic society in Malaysia is coping with these problems that are increasing at a phenomenal rate in the west. This study investigated computer usage, awareness of ergonomic modifications of computer furniture and peripherals, symptoms of CVS and risk of developing OOS. A cross-sectional questionnaire study of 136 computer users was conducted on a sample population of university students and office staff. A 'Modified Rapid Upper Limb Assessment (RULA) for office work' technique was used for evaluation of OOS. The prevalence of CVS was surveyed incorporating a 10-point scoring system for each of its various symptoms. It was found that many were using standard keyboard and mouse without any ergonomic modifications. Around 50% of those with some low back pain did not have an adjustable backrest. Many users had higher RULA scores of the wrist and neck suggesting increased risk of developing OOS, which needed further intervention. Many (64%) were using refractive corrections and still had high scores of CVS commonly including eye fatigue, headache and burning sensation. The increase of CVS scores (suggesting more subjective symptoms) correlated with increase in computer usage spells. It was concluded that further onsite studies are needed, to follow up this survey to decrease the risks of developing CVS and OOS amongst young computer users.

  14. FORMING SCHOOLCHILD’S PERSONALITY IN COMPUTER STUDY LESSONS AT PRIMARY SCHOOL

    Directory of Open Access Journals (Sweden)

    Natalia Salan

    2017-04-01

    Full Text Available The influence of computer on the formation of primary schoolchildren’s personality and their implementing into learning activity are considered in the article. Based on the materials of state standards and the Law of Ukraine on Higher Education the concepts “computer”, “information culture” are defined, modern understanding of the concept “basics of computer literacy” is identified. The main task of school propaedeutic course in Computer Studies is defined. Interactive methods of activity are singled out. They are didactic games, designing, research, collaboration in pairs, and group interaction, etc. The essential characteristics of didactic game technologies are distinguished, the peculiarities of their use at primary school in Computer Study lessons are analyzed. Positive and negative aspects of using these technologies in Computer Study lessons are defined. The expediency of using game technologies while organizing students’ educational and cognitive activity in Computer Studies is substantiated. The idea to create a school course “Computer Studies at primary school” is caused by the wide introduction of computer technics into the educational system. Today’s schoolchild has to be able to use a computer as freely and easily as he can use a pen, a pencil or a ruler. That’s why it is advisable to start studying basics of Computer Studies at the primary school age. This course is intended for the pupils of the 2nd-4th forms. Firstly, it provides mastering practical skills of computer work and, secondly, it anticipates the development of children’s logical and algorithmic thinking styles. At these lessons students acquire practical skills to work with information on the computer. Having mastered the computer skills at primary school, children will be able to use it successfully in their work. In senior classes they will be able to realize acquired knowledge of the methods of work with information, ways of problem solving

  15. Integrating user studies into computer graphics-related courses.

    Science.gov (United States)

    Santos, B S; Dias, P; Silva, S; Ferreira, C; Madeira, J

    2011-01-01

    This paper presents computer graphics. Computer graphics and visualization are essentially about producing images for a target audience, be it the millions watching a new CG-animated movie or the small group of researchers trying to gain insight into the large amount of numerical data resulting from a scientific experiment. To ascertain the final images' effectiveness for their intended audience or the designed visualizations' accuracy and expressiveness, formal user studies are often essential. In human-computer interaction (HCI), such user studies play a similar fundamental role in evaluating the usability and applicability of interaction methods and metaphors for the various devices and software systems we use.

  16. Integration of case study approach, project design and computer ...

    African Journals Online (AJOL)

    Integration of case study approach, project design and computer modeling in managerial accounting education ... Journal of Fundamental and Applied Sciences ... in the Laboratory of Management Accounting and Controlling Systems at the ...

  17. Evaluation of Microstructure and Transport Properties of Deteriorated Cementitious Materials from Their X-ray Computed Tomography (CT) Images.

    Science.gov (United States)

    Promentilla, Michael Angelo B; Cortez, Shermaine M; Papel, Regina Anne Dc; Tablada, Bernadette M; Sugiyama, Takafumi

    2016-05-19

    Pore structure, tortuosity and permeability are considered key properties of porous materials such as cement pastes to understand their long-term durability performance. Three-dimensional image analysis techniques were used in this study to quantify pore size, effective porosity, tortuosity, and permeability from the X-ray computed tomography (CT) images of deteriorated pastes that were subjected to accelerated leaching test. X-ray microtomography is a noninvasive three-dimensional (3D) imaging technique which has been recently gaining attention for material characterization. Coupled with 3D image analysis, the digitized pore can be extracted and computational simulation can be applied to the pore network to measure relevant microstructure and transport properties. At a spatial resolution of 0.50 μm, the effective porosity (ψ e ) was found to be in the range of 0.04 to 0.33. The characteristic pore size ( d ) using a local thickness algorithm was found to be in the range of 3 to 7 μm. The geometric tortuosity (τ g ) based on a 3D random walk simulation in the percolating pore space was found to be in the range of 2.00 to 7.45. The water permeability values ( K ) using US NIST Permeability Stokes Solver range from an order of magnitudes of 10 -14 to 10 -17 m². Indications suggest that as effective porosity increases, the geometric tortuosity increases and the permeability decreases. Correlation among these microstructure and transport parameters is also presented in this study.

  18. Computational Design of Non-natural Sugar Alcohols to Increase Thermal Storage Density: Beyond Existing Organic Phase Change Materials.

    Science.gov (United States)

    Inagaki, Taichi; Ishida, Toyokazu

    2016-09-14

    Thermal storage, a technology that enables us to control thermal energy, makes it possible to reuse a huge amount of waste heat, and materials with the ability to treat larger thermal energy are in high demand for energy-saving societies. Sugar alcohols are now one promising candidate for phase change materials (PCMs) because of their large thermal storage density. In this study, we computationally design experimentally unknown non-natural sugar alcohols and predict their thermal storage density as a basic step toward the development of new high performance PCMs. The non-natural sugar alcohol molecules are constructed in silico in accordance with the previously suggested molecular design guidelines: linear elongation of a carbon backbone, separated distribution of OH groups, and even numbers of carbon atoms. Their crystal structures are then predicted using the random search method and first-principles calculations. Our molecular simulation results clearly demonstrate that the non-natural sugar alcohols have potential ability to have thermal storage density up to ∼450-500 kJ/kg, which is significantly larger than the maximum thermal storage density of the present known organic PCMs (∼350 kJ/kg). This computational study suggests that, even in the case of H-bonded molecular crystals where the electrostatic energy contributes mainly to thermal storage density, the molecular distortion and van der Waals energies are also important factors to increase thermal storage density. In addition, the comparison between the three eight-carbon non-natural sugar alcohol isomers indicates that the selection of preferable isomers is also essential for large thermal storage density.

  19. Computed tomographic study of the complication of head injury

    International Nuclear Information System (INIS)

    Kojima, Tadashi; Waga, Shiro

    1982-01-01

    Computed tomography (CT) is quite effective in the diagnosis of traumatic intracranial hemorrhage and cerebral contusion. Two hundred and nine consecutive patients with head injury were admitted to the hospital and studied by CT in the year from 1977 to 1980. Fourty-sevenof 209 patients had the complications of head injury, including 6 patients with carotidcavernous fistula (CCF), 6 with traumatic aneurysm, 10 with pneumocephalus, 4 with intracranial foreign body, 15 with optic nerve injury, and 14 with other cranial nerve palsy. Five patients with CCF had abnormal finding on CT. Two traumatic aneurysms of the superficial temporal artery were visualized on CT after injection of contrast material, but all traumatic aneurysms of the carotid siphon were not seven on CT. CT in all 10 patients with pneumocephalus and in all 4 patients with intracranial foreign body was of diagnostic value: On CT in two patients even small air bubbles were seen in details. In the CT examination of 29 patients who presented with cranial nerve injury, we could not find out any abnormality on CT. We emphasize that CT is much less effective in the diagnosis of vascular complication of head injury and traumatic cranial nerve injury. (author)

  20. Experimental and computational study of thaumasite structure

    Energy Technology Data Exchange (ETDEWEB)

    Scholtzová, Eva, E-mail: Eva.Scholtzova@savba.sk [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36 Bratislava (Slovakia); Kucková, Lenka; Kožíšek, Jozef [Department of Physical Chemistry, Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava (Slovakia); Pálková, Helena [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36 Bratislava (Slovakia); Tunega, Daniel [Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 36 Bratislava (Slovakia); Institute for Soil Science, University of Natural Resources and Life Sciences, Peter-Jordanstrasse 82, A-1190 Wien (Austria)

    2014-05-01

    The structure of thaumasite has been studied experimentally by means of a single crystal X-ray diffraction and FTIR methods, and theoretically using density functional theory (DFT) method. Very good agreement was achieved between calculated and experimental structural parameters. In addition, calculations offered the refinement of the positions of the hydrogen atoms. The detailed analysis of the hydrogen bonds existing in the thaumasite structure has been performed. Several types of hydrogen bonds have been classified. The water molecules coordinating Ca{sup 2+} cation act as proton donors in moderate O-H···O hydrogen bonds formed with CO₃⁻²and SO₄⁻² anions. The multiple O-H···O hydrogen bonds exist among water molecules themselves. Finally, relatively weak hydrogen bonds form water molecules with the OH groups from the coordination sphere of the Si(OH)₆⁻² anion. Further, calculated vibrational spectrum allowed complete assignment of all vibrational modes which are not available from the experimental spectrum that has a complex structure with overlapped bands, especially below 1500 cm⁻¹. Highlights: • The thaumasite structure was studied experimentally and using DFT method. • We used DFT method for the refinement of the positions of hydrogen atoms. • A detailed analysis of the hydrogen bonds was done. • A complete assignment of all bands to particular types of vibrations was done.

  1. Factors affecting the adoption of cloud computing: an exploratory study

    OpenAIRE

    Morgan, Lorraine; Conboy, Kieran

    2013-01-01

    peer-reviewed While it is widely acknowledged that cloud computing has the potential to transform a large part of the IT industry, issues surrounding the adoption of cloud computing have received relatively little attention. Drawing on three case studies of service providers and their customers, this study will contribute to the existing cloud technologies literature that does not address the complex and multifaceted nature of adoption. The findings are analyzed using the adoption of innov...

  2. DIAGNOSTIC POSSIBILITIES OF 3D-COMPUTED TOMOGRAPHY WITH INTRALESIONAL APPLICATION OF CONTRAST MATERIAL IN A CASE OF VERY LARGE RADICULAR MAXILLARY CYST - A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Galina Gavazova

    2017-09-01

    Full Text Available Introduction: Diagnosis of odontogenic cysts despite their benign nature is a critical and challenging problem. Aim: The aim of this article is to demonstrate a different diagnostic approach in case of very large odontogenic cyst. Materials and Methods: This study was executed on one male patient aged of 38 using 3D computed tomography and contrast material inside the lesion. Differential diagnosis made by the residents was compared to the histopathological examination as the gold standard for identifying the nature of the cysts. Results: This diagnostic approach using 3D computed tomography combined with contrast material injected inside the lesion shows the real borders of the cyst of the maxilla and helps oral surgeon in planning the volume of the surgical intervention. Conclusion: Precise diagnose ensure the possibility of doing the optimal surgical intervention- a precondition for best wound healing.

  3. Computational science simulation of laser materials processing and provision of their irradiation conditions

    International Nuclear Information System (INIS)

    Muramatsu, Toshiharu

    2016-01-01

    In laser processing, it is necessary for achieving the intended performance and product, to understand the complex physical courses including melting and solidification phenomena occurring in laser processing, and thus to set proper laser irradiation conditions. This condition optimization work requires an enormous amount of overhead due to repeated efforts, and has become a cause for inhibiting the introduction of laser processing technology into the industrial field that points to the small lot production of many products. JAEA tried to make it possible to quantitatively handle the complex physical course from the laser light irradiation to the fabricating material until the completion of processing, and is under development of the computational science simulation code SPLICE that connects micro behavior and macro behavior through a multi-level scale model. This SPLICE is able to visualize the design space and to reduce the overhead associated with the setting of laser irradiation conditions and the like, which gives the prospect of being effective as a tool for front-loading. This approach has been confirmed to be effective for the welding and fusing process. (A.O.)

  4. Application of symbolic computations to the constitutive modeling of structural materials

    Science.gov (United States)

    Arnold, Steven M.; Tan, H. Q.; Dong, X.

    1990-01-01

    In applications involving elevated temperatures, the derivation of mathematical expressions (constitutive equations) describing the material behavior can be quite time consuming, involved and error-prone. Therefore intelligent application of symbolic systems to faciliate this tedious process can be of significant benefit. Presented here is a problem oriented, self contained symbolic expert system, named SDICE, which is capable of efficiently deriving potential based constitutive models in analytical form. This package, running under DOE MACSYMA, has the following features: (1) potential differentiation (chain rule), (2) tensor computations (utilizing index notation) including both algebraic and calculus; (3) efficient solution of sparse systems of equations; (4) automatic expression substitution and simplification; (5) back substitution of invariant and tensorial relations; (6) the ability to form the Jacobian and Hessian matrix; and (7) a relational data base. Limited aspects of invariant theory were also incorporated into SDICE due to the utilization of potentials as a starting point and the desire for these potentials to be frame invariant (objective). The uniqueness of SDICE resides in its ability to manipulate expressions in a general yet pre-defined order and simplify expressions so as to limit expression growth. Results are displayed, when applicable, utilizing index notation. SDICE was designed to aid and complement the human constitutive model developer. A number of examples are utilized to illustrate the various features contained within SDICE. It is expected that this symbolic package can and will provide a significant incentive to the development of new constitutive theories.

  5. Yield asymmetry design of magnesium alloys by integrated computational materials engineering

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dongsheng [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Khaleel, Mohammad [Qatar Foundation Research adn Development (Qatar); Ahzi, Said [Univ. of Strasbourg (France)

    2013-11-01

    Deformation asymmetry of magnesium alloys is an important factor on machine design in the automobile industry. Represented by the ratio of compressive yield stress (CYS) against tensile yield stress (TYS), deformation asymmetry is strongly related to texture and grain size. A polycrystalline viscoplasticity model, modified intermediate Φ-model, is used to predict the deformation behavior of magnesium alloys with different grain sizes. Validated with experimental results, integrated computational materials engineering is applied to find out the route in achieving desired asymmetry via thermomechanical processing. For example, CYS/TYS in rolled texture is smaller than 1 under different loading directions. In other textures, such as extruded texture, CYS/TYS is large along the normal direction. Starting from rolled texture, asymmetry will increase to close to 1 along the rolling direction after being compressed to a strain of 0.2. Our modified Φ-model also shows that grain refinement increases CYS/TYS. Along with texture control, grain refinement also can optimize the yield asymmetry. After the grain size decreases to a critical value, CYS/TYS reaches to 1 because CYS increases much faster than TYS. By tailoring the microstructure using texture control and grain refinement, it is achievable to optimize yield asymmetry in wrought magnesium alloys.

  6. Hispanic women overcoming deterrents to computer science: A phenomenological study

    Science.gov (United States)

    Herling, Lourdes

    The products of computer science are important to all aspects of society and are tools in the solution of the world's problems. It is, therefore, troubling that the United States faces a shortage in qualified graduates in computer science. The number of women and minorities in computer science is significantly lower than the percentage of the U.S. population which they represent. The overall enrollment in computer science programs has continued to decline with the enrollment of women declining at a higher rate than that of men. This study addressed three aspects of underrepresentation about which there has been little previous research: addressing computing disciplines specifically rather than embedding them within the STEM disciplines, what attracts women and minorities to computer science, and addressing the issues of race/ethnicity and gender in conjunction rather than in isolation. Since women of underrepresented ethnicities are more severely underrepresented than women in general, it is important to consider whether race and ethnicity play a role in addition to gender as has been suggested by previous research. Therefore, this study examined what attracted Hispanic women to computer science specifically. The study determines whether being subjected to multiple marginalizations---female and Hispanic---played a role in the experiences of Hispanic women currently in computer science. The study found five emergent themes within the experiences of Hispanic women in computer science. Encouragement and role models strongly influenced not only the participants' choice to major in the field, but to persist as well. Most of the participants experienced a negative atmosphere and feelings of not fitting in while in college and industry. The interdisciplinary nature of computer science was the most common aspect that attracted the participants to computer science. The aptitudes participants commonly believed are needed for success in computer science are the Twenty

  7. Calorimetric and computational study of indanones.

    Science.gov (United States)

    Matos, M Agostinha R; Miranda, Margarida S; Monte, Manuel J S; Santos, Luís M N B F; Morais, Victor M F; Chickos, James S; Umnahanant, Patamaporn; Liebman, Joel F

    2007-11-01

    Condensed phase standard (p degrees = 0.1 MPa) molar enthalpies of formation for 1-indanone, 2-indanone, and 1,3-indandione were derived from the standard molar enthalpies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The standard molar enthalpies of sublimation for 1-indanone and 2-indanone, at T = 298.15 K, were measured both by correlation-gas chromatography and by Calvet microcalorimetry leading to a mean value for each compound. For 1,3-indandione, the standard molar enthalpy of sublimation was derived from the vapor pressure dependence on temperature. The following enthalpies of formation in gas phase, at T = 298.15 K, were then derived: 1-indanone, -64.0 +/- 3.8 kJ mol(-1); 2-indanone, -56.6 +/- 4.8 kJ mol(-1); 1,3-indandione, -165.0 +/- 2.6 kJ mol(-1). The vaporization and fusion enthalpies of the indanones studied are also reported. In addition, theoretical calculations using the density functional theory with the B3LYP and MPW1B95 energy functionals and the 6-311G** and cc-pVTZ basis sets have been performed for these molecules and the corresponding one-ring species to obtain the most stable geometries and to access their energetic stabilities.

  8. A study on computed tomography on schizophrenia

    International Nuclear Information System (INIS)

    Mikami, Akihiro; Watanabe, Hiroshi

    1981-01-01

    Many pneumoencephalographical studies of morphological changes in the brain of schizophreniacs have been reported, but those observations were not in good agreement. CT findings of 191 schizophreniacs were compared with those of 100 controls, and their relation to the clinical course was evaluated. Observation was made on the following 6 regions; frontal subarachnoid space (F), frontal longitudinal fissure (I), Sylvius fissure (S), frontoparietal fissure (P), lateral ventricle (Lv) and third ventricle. On CT scan, the incidence of enlargement of F, L, S, and Lv was significantly higher in the schizophreniacs than in the control, and it was especially high in the patients with severe disturbance of personal contact, language activity, spontaneity, and expression of feelings (non-relievable group type II). No certain localization of enlargement was observed in the schizophreniacs. There was no definite correlation between I.Q. or duration of the disease and the incidence of enlargement. In type I, the frequency of enlargement in the patients with electro schock therapy (EST) was significantly higher than that in the patients without EST. (Ueda, J.)

  9. Reduction of metal artifact in three-dimensional computed tomography (3D CT) with dental impression materials.

    Science.gov (United States)

    Park, W S; Kim, K D; Shin, H K; Lee, S H

    2007-01-01

    Metal Artifact still remains one of the main drawbacks in craniofacial Three-Dimensional Computed Tomography (3D CT). In this study, we tried to test the efficacy of additional silicone dental impression materials as a "tooth shield" for the reduction of metal artifact caused by metal restorations and orthodontic appliances. 6 phantoms with 4 teeth were prepared for this in vitro study. Orthodontic bracket, bands and amalgam restorations were placed in each tooth to reproduce various intraoral conditions. Standardized silicone shields were fabricated and placed around the teeth. CT image acquisition was performed with and without silicone shields. Maximum value, mean, and standard deviation of Hounsfield Units (HU) were compared with the presence of silicone shields. In every situation, metal artifacts were reduced in quality and quantity when silicone shields are used. Amalgam restoration made most serious metal artifact. Silicone shields made by dental impression material might be effective way to reduce the metal artifact caused by dental restoration and orthodontic appliances. This will help more excellent 3D image from 3D CT in craniofacial area.

  10. Computational and theoretical studies of globular proteins

    Science.gov (United States)

    Pagan, Daniel L.

    Protein crystallization is often achieved in experiment through a trial and error approach. To date, there exists a dearth of theoretical understanding of the initial conditions necessary to promote crystallization. While a better understanding of crystallization will help to create good crystals suitable for structure analysis, it will also allow us to prevent the onset of certain diseases. The core of this thesis is to model and, ultimately, understand the phase behavior of protein particles in solution. Toward this goal, we calculate the fluid-fluid coexistence curve in the vicinity of the metastable critical point of the modified Lennard-Jones potential, where it has been shown that nucleation is increased by many orders of magnitude. We use finite-size scaling techniques and grand canonical Monte Carlo simulation methods. This has allowed us to pinpoint the critical point and subcritical region with high accuracy in spite of the critical fluctuations that hinder sampling using other Monte Carlo techniques. We also attempt to model the phase behavior of the gamma-crystallins, mutations of which have been linked to genetic cataracts. The complete phase behavior of the square well potential at the ranges of attraction lambda = 1.15 and lambda = 1.25 is calculated and compared with that of the gammaII-crystallin. The role of solvent is also important in the crystallization process and affects the phase behavior of proteins in solution. We study a model that accounts for the contribution of the solvent free-energy to the free-energy of globular proteins. This model allows us to model phase behavior that includes solvent.

  11. Biomimicry in Product Design through Materials Selection and Computer Aided Engineering

    Science.gov (United States)

    Alexandridis, G.; Tzetzis, D.; Kyratsis, P.

    2016-11-01

    The aim of this study is to demonstrate a 7-step methodology that describes the way nature can act as a source of inspiration for the design and the development of a product. Furthermore, it suggests special computerized tools and methods for the product optimization regarding its environmental impact i.e. material selection, production methods. For validation purposes, a garden chaise lounge that imitates the form of a scorpion was developed as a result for the case study and the presentation of the current methodology.

  12. Learning by Computer Simulation Does Not Lead to Better Test Performance on Advanced Cardiac Life Support Than Textbook Study.

    Science.gov (United States)

    Kim, Jong Hoon; Kim, Won Oak; Min, Kyeong Tae; Yang, Jong Yoon; Nam, Yong Taek

    2002-01-01

    For an effective acquisition and the practical application of rapidly increasing amounts of information, computer-based learning has already been introduced in medical education. However, there have been few studies that compare this innovative method to traditional learning methods in studying advanced cardiac life support (ACLS). Senior medical students were randomized to computer simulation and a textbook study. Each group studied ACLS for 150 minutes. Tests were done one week before, immediately after, and one week after the study period. Testing consisted of 20 questions. All questions were formulated in such a way that there was a single best answer. Each student also completed a questionnaire designed to assess computer skills as well as satisfaction with and benefit from the study materials. Test scores improved after both textbook study and computer simulation study in both groups but the improvement in scores was significantly higher for the textbook group only immediately after the study. There was no significant difference between groups in their computer skill and satisfaction with the study materials. The textbook group reported greater benefit from study materials than did the computer simulation group. Studying ACLS with a hard copy textbook may be more effective than computer simulation for the acquisition of simple information during a brief period. However, the difference in effectiveness is likely transient.

  13. Moessbauer Spectroscopy study of Quimsachata Volcano materials

    International Nuclear Information System (INIS)

    Dominguez, A.G.B.

    1988-01-01

    It has been studied volcanic lava from Quimsachata Volcano in Pem. Moessbauer Spectroscopy, X-ray diffraction, electronic and optical microscopy allowed the identification of different mineralogical phases. (A.C.AS.) [pt

  14. Computational modeling of the behavior of nuclear materials (2). Molecular simulations for nuclear materials. Current situation and future perspective

    International Nuclear Information System (INIS)

    Okita, Taira; Itakura, Mitsuhiro

    2017-01-01

    Molecular simulations for nuclear materials aim to reproduce atomistic-scale phenomena induced by irradiation and infer the change in material properties. In the present work, recent progress in this field is presented. In particular, the following three topics are explained: (1) Quantification of lattice defects formation process induced by fast neutron collision. (2) Identification of dislocation-channeling mechanism induced by interactions between defect clusters and dislocations. (3) Modeling of the three dimensional movement of defect clusters using molecular dynamics and kinetic Monte Carlo simulations. (author)

  15. Spacelab experiment computer study. Volume 1: Executive summary (presentation)

    Science.gov (United States)

    Lewis, J. L.; Hodges, B. C.; Christy, J. O.

    1976-01-01

    A quantitative cost for various Spacelab flight hardware configurations is provided along with varied software development options. A cost analysis of Spacelab computer hardware and software is presented. The cost study is discussed based on utilization of a central experiment computer with optional auxillary equipment. Groundrules and assumptions used in deriving the costing methods for all options in the Spacelab experiment study are presented. The groundrules and assumptions, are analysed and the options along with their cost considerations, are discussed. It is concluded that Spacelab program cost for software development and maintenance is independent of experimental hardware and software options, that distributed standard computer concept simplifies software integration without a significant increase in cost, and that decisions on flight computer hardware configurations should not be made until payload selection for a given mission and a detailed analysis of the mission requirements are completed.

  16. A study on the safety regulation of byproduct material (II)

    Energy Technology Data Exchange (ETDEWEB)

    Song, Jong Sun; Song, Yang Su [Chosun Univ., Gwangju (Korea, Republic of)

    2000-03-15

    The scope of this study consists of : in relating to the domestic license of byproduct material, a survey of technical criteria and status of regulation in U.S.A., a determination of range of application and contents of byproduct material, a tentative suggestion of related technical criteria and regulatory system. A study was performed about the above topics to establish the safe regulation of byproduct material institutionally, and this can be contributed in establishing the proper domestic technical criteria related.

  17. Creating a Multi-material Probing Error Test for the Acceptance Testing of Dimensional Computed Tomography Systems

    DEFF Research Database (Denmark)

    Borges de Oliveira, Fabrício; Stolfi, Alessandro; Bartscher, Markus

    2017-01-01

    The requirement of quality assurance of inner and outer structures in complex multi-material assemblies is one important factor that has encouraged the use of industrial X-ray computed tomography (CT). The application of CT as a coordinate measurement system (CMS) has opened up new challenges...

  18. Three-Dimensional Printing of X-Ray Computed Tomography Datasets with Multiple Materials Using Open-Source Data Processing

    Science.gov (United States)

    Sander, Ian M.; McGoldrick, Matthew T.; Helms, My N.; Betts, Aislinn; van Avermaete, Anthony; Owers, Elizabeth; Doney, Evan; Liepert, Taimi; Niebur, Glen; Liepert, Douglas; Leevy, W. Matthew

    2017-01-01

    Advances in three-dimensional (3D) printing allow for digital files to be turned into a "printed" physical product. For example, complex anatomical models derived from clinical or pre-clinical X-ray computed tomography (CT) data of patients or research specimens can be constructed using various printable materials. Although 3D printing…

  19. Using Computational and Mechanical Models to Study Animal Locomotion

    OpenAIRE

    Miller, Laura A.; Goldman, Daniel I.; Hedrick, Tyson L.; Tytell, Eric D.; Wang, Z. Jane; Yen, Jeannette; Alben, Silas

    2012-01-01

    Recent advances in computational methods have made realistic large-scale simulations of animal locomotion possible. This has resulted in numerous mathematical and computational studies of animal movement through fluids and over substrates with the purpose of better understanding organisms’ performance and improving the design of vehicles moving through air and water and on land. This work has also motivated the development of improved numerical methods and modeling techniques for animal locom...

  20. Pulmonary artery aneurysm in Bechcet's disease: helical computed tomography study

    International Nuclear Information System (INIS)

    Munoz, J.; Caballero, P.; Olivera, M. J.; Cajal, M. L.; Caniego, J. L.

    2000-01-01

    Behcet's disease is a vasculitis of unknown etiology that affects arteries and veins of different sizes and can be associated with pulmonary artery aneurysms. We report the case of a patient with Behcet's disease and a pulmonary artery aneurysm who was studied by means of plain chest X ray, helical computed tomography and pulmonary arteriography. Helical computed tomography is a reliable technique for the diagnosis and follow-up of these patients. (Author) 9 refs

  1. Studies on selected polymeric materials using the photoacoustic spectroscopic technique

    International Nuclear Information System (INIS)

    Singh, Hukum

    2011-01-01

    Polymethylmethacrylate—graft—polybisphenol—A-carbonate (PMMA-G-PC) with 50% grafting is synthesized. The graft co-polymerization of methylmethacrylate (0.036 mol · lit −1 ) onto polybisphenol—A-carbonate (0.5 g) in the presence of a redox couple formed from potassium persulphate (40 mol · lit −1 ) and thio-urea (30 mmol · lit −1 ) in aqueous nitric acid (0.18 M, 100 ml) in air at (45±2) °C for 3.0 h. Condensation of (PMMA-G-PC) with N- [p-(carboxyl phenyl amino acetic acid)] hydrazide (PCPH) affords polybisphenol-A-carbonate-graft-polymethylmethacrylate hydrazide (PCGH). The photoacoustic (PA) spectra of (PCGH) are recorded in a wavelength range from 200 nm to 800 nm at a modulation frequency of 22 Hz, and compared with those of pure polybisphenol-A-carbonate (PC), (PMMA-G-PC) and (PCPH). In the present work, a non-destructive and non-contact analytical method, namely the photoacoustic technique, is successfully implemented for optical and thermal characterization of selected polymeric materials. The indigenous PA spectrometer used in the present study consists of a 300-W xenon arc lamp, a lock-in amplifier, a chopper, a (1/8)-m monochromator controlled by computer and a home-made PA cell. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. Uses of reactor neutrons for studying the microcomposition of materials

    International Nuclear Information System (INIS)

    Jervis, R.E.

    1993-01-01

    Reactor neutrons constitute excellents 'probes' for exploring and measuring a wide range both of minor and trace constituents in solids and liquids with high sensitivity because of their transparency in materials. Nondestructive neutron prompt-gamma analysis (PGA) utilizing either cold or thermal neutrons, such as at JRR-3M, is compared and contrasted to the more common (delayed) instrumental neutron activation analysis (INAA) and epithermal NAA. Clearly PGA offers high sensitivity for selected elements: B, H, Cd and REE's in suitable matrices, and is therefore, complementary to INAA which is not as useful for them, or for Ni, Sn, Fe, C or N. Recent INAA applications in our laboratory that demonstrate some of the uniqueness of neutron methods include use of epithermal neutrons for small biological specimens to measure Cd, K, As, Zn and, multielemental INAA for environmental pollution studies. The latter involves large data sets of multielemental concentrations which are subjected to statistical multivariant factor analysis to reveal unknown or unsuspected quantitative relationships among groups of trace constituents. These patterns, or 'factors' are shown to be uniquely related to pollution sources and can be utilized to compute the relative source contributions at a given receptor site. (author)

  3. Environmental reference materials methods and case studies

    DEFF Research Database (Denmark)

    Schramm-Nielsen, Karina Edith

    1998-01-01

    . This study lasted 22 months as well. The samples were produced and stored according to a 2³ factorial design. The influences of storage temperature, UV radiation and ultra-filtration on the stability of NH4-N and total phosphorous have been investigated. A Youden plot method is suggested for the graphical....... The methods have been evaluated with regard to their robustness towards variations in the chemical analytical method and with regard to the number of times a significant out of control situation is indicated. The second study regards the stability of NH4-N and total phosphorous in autoclaved seawater samples...... with wastewater. The purpose was to improve ortho-phosphate (and total phosphorous) homogeneity. A procedure is suggested which includes freeze-drying and redissolving. All calculations have been performed in SAS® primarily by means of elementary procedures, analyses of variance procedures, SAS Insight and SAS...

  4. A Qualitative Study of Students' Computational Thinking Skills in a Data-Driven Computing Class

    Science.gov (United States)

    Yuen, Timothy T.; Robbins, Kay A.

    2014-01-01

    Critical thinking, problem solving, the use of tools, and the ability to consume and analyze information are important skills for the 21st century workforce. This article presents a qualitative case study that follows five undergraduate biology majors in a computer science course (CS0). This CS0 course teaches programming within a data-driven…

  5. A Resonant Damping Study Using Piezoelectric Materials

    Science.gov (United States)

    Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.

    2008-01-01

    Excessive vibration of turbomachinery blades causes high cycle fatigue (HCF) problems requiring damping treatments to mitigate vibration levels. Based on the technical challenges and requirements learned from previous turbomachinery blade research, a feasibility study of resonant damping control using shunted piezoelectric patches with passive and active control techniques has been conducted on cantilever beam specimens. Test results for the passive damping circuit show that the optimum resistive shunt circuit reduces the third bending resonant vibration by almost 50%, and the optimum inductive circuit reduces the vibration by 90%. In a separate test, active control reduced vibration by approximately 98%.

  6. Transmission electron microscope studies of extraterrestrial materials

    Science.gov (United States)

    Keller, Lindsay P.

    1995-01-01

    Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

  7. A Reflective Study into Children's Cognition When Making Computer Games

    Science.gov (United States)

    Allsop, Yasemin

    2016-01-01

    In this paper, children's mental activities when making digital games are explored. Where previous studies have mainly focused on children's learning, this study aimed to unfold the children's thinking process for learning when making computer games. As part of an ongoing larger scale study, which adopts an ethnographic approach, this research…

  8. Ion-atom collisions for materials study

    International Nuclear Information System (INIS)

    Loaiza S, N.S.

    1976-01-01

    The diffusion process of silver in aluminium was studied in thin films as a function of temperature, the most important characteristics of dispersor atoms that technique permits us to study are the atomic mass and depth into the solid. This is possible because when a sample is bombarded with ions of a given energy, the ions are dispersed with different energies for different masses and depths, hence this technique is a useful instrument for research into the physical processes which ocurr in thin films up to depths of several microns, one of the results obtained after the bombardment of the target with protons having an energy of 650 KeV was that when the target reached a temperature of approximately 40 0 C, 80 0 C, 110 0 C and 160 0 C during 15 minutes and the spectra of heated and unheated targets were compared it was found that the aluminium peak, the valley, the silver peak and the peak over the silver peak change with the increase of temperature and tend to get mixed, that is to say that silver and the aluminium are diffusing themselves. The analysis is essentially qualitative with this technique we ca also measure the thickness of thin films, the silver thickness was measured (3320A). (author)

  9. New preparation of fish material for interlaboratory study on PFCs

    NARCIS (Netherlands)

    Korytar, P.; Lohman, M.; Kwadijk, C.J.A.F.; Barneveld, van E.

    2007-01-01

    The Institute for Environmental Studies, Vrije Universiteit (IVM) has requested Wageningen IMARES to prepare a new fish material for use in the interlaboratory performance study on analysis of perfluorinated compounds (PFCs) due to the low amount of contaminants in the previously prepared material.

  10. Preparation of fish material for interlaboratory study on PFCs

    NARCIS (Netherlands)

    Korytar, P.; Kwadijk, C.J.A.F.; Lohman, M.; Barneveld, van E.

    2007-01-01

    The Institute for Environmental Studies, Vrije Universiteit (IVM) has requested Wageningen IMARES for the preparation of fish material for use in interDlaboratory performance study on analysis of perfluorinated compounds (PFCs). It was requested that the material should be prepared from fillet of

  11. Electrostatic Levitation for Studies of Additive Manufactured Materials

    Science.gov (United States)

    SanSoucie, Michael P.; Rogers, Jan R.; Tramel, Terri

    2014-01-01

    The electrostatic levitation (ESL) laboratory at NASA's Marshall Space Flight Center is a unique facility for investigators studying high temperature materials. The laboratory boasts two levitators in which samples can be levitated, heated, melted, undercooled, and resolidified. Electrostatic levitation minimizes gravitational effects and allows materials to be studied without contact with a container or instrumentation. The lab also has a high temperature emissivity measurement system, which provides normal spectral and normal total emissivity measurements at use temperature. The ESL lab has been instrumental in many pioneering materials investigations of thermophysical properties, e.g., creep measurements, solidification, triggered nucleation, and emissivity at high temperatures. Research in the ESL lab has already led to the development of advanced high temperature materials for aerospace applications, coatings for rocket nozzles, improved medical and industrial optics, metallic glasses, ablatives for reentry vehicles, and materials with memory. Modeling of additive manufacturing materials processing is necessary for the study of their resulting materials properties. In addition, the modeling of the selective laser melting processes and its materials property predictions are also underway. Unfortunately, there is very little data for the properties of these materials, especially of the materials in the liquid state. Some method to measure thermophysical properties of additive manufacturing materials is necessary. The ESL lab is ideal for these studies. The lab can provide surface tension and viscosity of molten materials, density measurements, emissivity measurements, and even creep strength measurements. The ESL lab can also determine melting temperature, surface temperatures, and phase transition temperatures of additive manufactured materials. This presentation will provide background on the ESL lab and its capabilities, provide an approach to using the ESL

  12. A numerical study on stress distribution across the ankle joint: Effects of material distribution of bone, muscle force and ligaments.

    Science.gov (United States)

    Mondal, Subrata; Ghosh, Rajesh

    2017-09-01

    The goal of this study is to develop a realistic three dimensional FE model of intact ankle joint. Three dimensional FE model of the intact ankle joint was developed using computed tomography data sets. The effect of muscle force, ligaments and proper material property distribution of bone on stress distribution across the intact ankle joint was studied separately. Present study indicates bone material property, ligaments and muscle force have influence on stress distribution across the ankle joint. Proper bone material, ligaments and muscle must be considered in the computational model for pre-clinical analysis of ankle prosthesis.

  13. Making nuclear power plant operational decisions using probabilistic safety assessment information and personal computers. Working material

    International Nuclear Information System (INIS)

    1991-01-01

    PRISIM described in this case study makes a PSA useful to decision makers like plant managers, operational personnel or safety assessors because it provides a rapid access to specific information and the ability to generate updated PSA results that reflect the plant status at a particular time. From the capabilities of PRISIM one can conclude that the ability of a user friendly update of the system model in the PC or changes in the data files at the computer is not realized to data. Also the calculation of averaged probabilities instead of time dependent instantaneous probabilities is a sort of a restriction and will be changed in the future. 5 refs, 34 figs, 3 tabs

  14. Multiscale Modeling of Carbon Fiber Reinforced Polymer (CFRP) for Integrated Computational Materials Engineering Process

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jiaying; Liang, Biao; Zhang, Weizhao; Liu, Zeliang; Cheng, Puikei; Bostanabad, Ramin; Cao, Jian; Chen, Wei; Liu, Wing Kam; Su, Xuming; Zeng, Danielle; Zhao, John

    2017-10-23

    In this work, a multiscale modeling framework for CFRP is introduced to study hierarchical structure of CFRP. Four distinct scales are defined: nanoscale, microscale, mesoscale, and macroscale. Information at lower scales can be passed to higher scale, which is beneficial for studying effect of constituents on macroscale part’s mechanical property. This bottom-up modeling approach enables better understanding of CFRP from finest details. Current study focuses on microscale and mesoscale. Representative volume element is used at microscale and mesoscale to model material’s properties. At microscale, unidirection CFRP (UD) RVE is used to study properties of UD. The UD RVE can be modeled with different volumetric fraction to encounter non-uniform fiber distribution in CFRP part. Such consideration is important in modeling uncertainties at microscale level. Currently, we identified volumetric fraction as the only uncertainty parameters in UD RVE. To measure effective material properties of UD RVE, periodic boundary conditions (PBC) are applied to UD RVE to ensure convergence of obtained properties. Properties of UD is directly used at mesoscale woven RVE modeling, where each yarn is assumed to have same properties as UD. Within woven RVE, there can be many potential uncertainties parameters to consider for a physical modeling of CFRP. Currently, we will consider fiber misalignment within yarn and angle between wrap and weft yarns. PBC is applied to woven RVE to calculate its effective material properties. The effect of uncertainties are investigated quantitatively by Gaussian process. Preliminary results of UD and Woven study are analyzed for efficacy of the RVE modeling. This work is considered as the foundation for future multiscale modeling framework development for ICME project.

  15. Case studies in intelligent computing achievements and trends

    CERN Document Server

    Issac, Biju

    2014-01-01

    Although the field of intelligent systems has grown rapidly in recent years, there has been a need for a book that supplies a timely and accessible understanding of this important technology. Filling this need, Case Studies in Intelligent Computing: Achievements and Trends provides an up-to-date introduction to intelligent systems.This edited book captures the state of the art in intelligent computing research through case studies that examine recent developments, developmental tools, programming, and approaches related to artificial intelligence (AI). The case studies illustrate successful ma

  16. Study to develop improved fire resistant aircraft passenger seat materials

    Science.gov (United States)

    Duskin, F. E.; Schutter, K. J.; Sieth, H. H.; Trabold, E. L.

    1980-01-01

    The Phase 3 study of the NASA 'Improved Fire Resistant Aircraft Seat Materials' involved fire tests of improved materials in multilayered combinations representative of cushion configurations. Tests were conducted to determine their thermal, smoke, and fire resistance characteristics. Additionally, a 'Design Guideline' for Fire Resistant Passenger Seats was written outlining general seat design considerations. Finally, a three-abreast 'Tourist Class' passenger seat assembly fabricated from the most advanced fire-resistant materials was delivered.

  17. COMPUTING

    CERN Multimedia

    M. Kasemann

    Overview In autumn the main focus was to process and handle CRAFT data and to perform the Summer08 MC production. The operational aspects were well covered by regular Computing Shifts, experts on duty and Computing Run Coordination. At the Computing Resource Board (CRB) in October a model to account for service work at Tier 2s was approved. The computing resources for 2009 were reviewed for presentation at the C-RRB. The quarterly resource monitoring is continuing. Facilities/Infrastructure operations Operations during CRAFT data taking ran fine. This proved to be a very valuable experience for T0 workflows and operations. The transfers of custodial data to most T1s went smoothly. A first round of reprocessing started at the Tier-1 centers end of November; it will take about two weeks. The Computing Shifts procedure was tested full scale during this period and proved to be very efficient: 30 Computing Shifts Persons (CSP) and 10 Computing Resources Coordinators (CRC). The shift program for the shut down w...

  18. Computers in the investigation of the impurity content of high-purity materials

    International Nuclear Information System (INIS)

    Makarov, Yu.B.; Yan'kov, S.V.

    1987-01-01

    The efficiency of the concept of data banks for the accumulation and processing of information is now generally acknowledged. In scientific investigations not only bibliographic but also factual data banks are becoming more and more prevalent. In this article, the authors consider the possibilities of providing a data bank on high-purity materials for the study of impurity contents. Also in this paper, the authors distinguish the following groups of problems that arise in the study of impurity composition and presents examples of their proposed solutions to these problems: the analysis of error and the determination of the most probably value of impurity concentration; the estimation of average properties of impurity composition with respect to groups of impurities and samples, and the forecast of the complete impurity composition

  19. A study on Computer-controlled Ultrasonic Scanning Device

    International Nuclear Information System (INIS)

    Huh, H.; Park, C. S.; Hong, S. S.; Park, J. H.

    1989-01-01

    Since the nuclear power plants in Korea have been operated in 1979, the nondestructive testing (NDT) of pressure vessels and/or piping welds plays an important role for maintaining the safety and integrity of the plants. Ultrasonic method is superior to the other NDT method in the viewpoint of the detectability of small flaw and accuracy to determine the locations, sizes, orientations, and shapes. As the service time of the nuclear power plants is increased, the radiation level from the components is getting higher. In order to get more quantitative and reliable results and secure the inspector from the exposure to high radiation level, automation of the ultrasonic equipment has been one of the important research and development(R and D) subject. In this research, it was attempted to visualize the shape of flaws presented inside the specimen using a Modified C-Scan technique. In order to develop Modified C-Scan technique, an automatic ultrasonic scanner and a module to control the scanner were designed and fabricated. IBM-PC/XT was interfaced to the module to control the scanner. Analog signals from the SONIC MARK II were digitized by Analog-Digital Converter(ADC 0800) for Modified C-Scan display. A computer program has been developed and has capability of automatic data acquisition and processing from the digital data, which consist of maximum amplitudes in each gate range and locations. The data from Modified C-Scan results was compared with shape from artificial defects using the developed system. Focal length of focused transducer was measured. The automatic ultrasonic equipment developed through this study is essential for more accurate, reliable, and repeatable ultrasonic experiments. If the scanner are modified to meet to appropriate purposes, it can be applied to automation of ultrasonic examination of nuclear power plants and helpful to the research on ultrasonic characterization of the materials

  20. Computational Material Modeling of Hydrated Cement Paste Calcium Silicate Hydrate (C-S-H) Chemistry Structure - Influence of Magnesium Exchange on Mechanical Stiffness: C-S-H Jennite

    Science.gov (United States)

    2015-04-27

    MODELING OF C-S-H Material chemistry level modeling following the principles and techniques commonly grouped under Computational Material Science is...Henmi, C. and Kusachi, I. Monoclinic tobermorite from fuka, bitchu-cho, Okoyama Perfecture. Japan J. Min. Petr. Econ . Geol. (1989)84:374-379. [22...31] Liu, Y. et al. First principles study of the stability and mechanical properties of MC (M=Ti, V, Zr, Nb, Hf and Ta) compounds. Journal of Alloys and Compounds. (2014) 582:500-504. 10

  1. Two Studies Examining Argumentation in Asynchronous Computer Mediated Communication

    Science.gov (United States)

    Joiner, Richard; Jones, Sarah; Doherty, John

    2008-01-01

    Asynchronous computer mediated communication (CMC) would seem to be an ideal medium for supporting development in student argumentation. This paper investigates this assumption through two studies. The first study compared asynchronous CMC with face-to-face discussions. The transactional and strategic level of the argumentation (i.e. measures of…

  2. Brain-computer interfacing under distraction: an evaluation study

    DEFF Research Database (Denmark)

    Brandl, Stephanie; Frølich, Laura; Höhne, Johannes

    2016-01-01

    Objective. While motor-imagery based brain-computer interfaces (BCIs) have been studied over many years by now, most of these studies have taken place in controlled lab settings. Bringing BCI technology into everyday life is still one of the main challenges in this field of research. Approach...

  3. Student Engagement with Computer-Generated Feedback: A Case Study

    Science.gov (United States)

    Zhang, Zhe

    2017-01-01

    In order to benefit from feedback on their writing, students need to engage effectively with it. This article reports a case study on student engagement with computer-generated feedback, known as automated writing evaluation (AWE) feedback, in an EFL context. Differing from previous studies that explored commercially available AWE programs, this…

  4. Effect of Saline Pushing after Contrast Material Injection in Abdominal Multidetector Computed Tomography with the Use of Different Iodine Concentrations

    International Nuclear Information System (INIS)

    Tatsugami, F.; Matsuki, M.; Kani, H.; Tanikake, M.; Miyao, M.; Yoshikawa, S.; Narabayashi, I.

    2006-01-01

    Purpose: To investigate whether saline pushing after contrast material improves hepatic vascular and parenchymal enhancement, and to determine whether this technique permits decreased contrast material concentration. Material and Methods: 120 patients who underwent hepatic multidetector computed tomography were divided randomly into four groups (Groups A-D): receiving 100 ml of contrast material (300 mgI/ml) only (A) or with 50 ml of saline solution (B); or 100 ml of contrast material (350 mgI/ml) only (C) or with 50 ml of saline solution (D). Computed tomography (CT) values of the aorta in the arterial phase, the portal vein in the portal venous inflow phase, and the liver in the hepatic phase were measured. Visualization of the hepatic artery and the portal vein by 3D CT angiography was evaluated as well. Results: Although the enhancement values of the aorta were not improved significantly with saline pushing, they continued at a high level to the latter slices with saline pushing. The enhancement value of the portal vein increased significantly and CT portography was improved with saline pushing. The enhancement value of the liver was not improved significantly using saline pushing. In a comparison between groups B and C, the enhancement values of the aorta and portal vein and the visualization of CT arteriography and portography were not statistically different. Conclusion: The saline pushing technique can contribute to a decrease in contrast material concentration for 3D CT arteriography and portography

  5. Doctors' experience with handheld computers in clinical practice: qualitative study.

    Science.gov (United States)

    McAlearney, Ann Scheck; Schweikhart, Sharon B; Medow, Mitchell A

    2004-05-15

    To examine doctors' perspectives about their experiences with handheld computers in clinical practice. Qualitative study of eight focus groups consisting of doctors with diverse training and practice patterns. Six practice settings across the United States and two additional focus group sessions held at a national meeting of general internists. 54 doctors who did or did not use handheld computers. Doctors who used handheld computers in clinical practice seemed generally satisfied with them and reported diverse patterns of use. Users perceived that the devices helped them increase productivity and improve patient care. Barriers to use concerned the device itself and personal and perceptual constraints, with perceptual factors such as comfort with technology, preference for paper, and the impression that the devices are not easy to use somewhat difficult to overcome. Participants suggested that organisations can help promote handheld computers by providing advice on purchase, usage, training, and user support. Participants expressed concern about reliability and security of the device but were particularly concerned about dependency on the device and over-reliance as a substitute for clinical thinking. Doctors expect handheld computers to become more useful, and most seem interested in leveraging (getting the most value from) their use. Key opportunities with handheld computers included their use as a stepping stone to build doctors' comfort with other information technology and ehealth initiatives and providing point of care support that helps improve patient care.

  6. EFL Teachers' Knowledge of the Use and Development of Computer-Assisted Language Learning (CALL) Materials

    Science.gov (United States)

    Dashtestani, Reza

    2014-01-01

    Even though there are a plethora of CALL materials available to EFL teachers nowadays, very limited attention has been directed toward the issue that most EFL teachers are merely the consumers of CALL materials. The main challenge is to equip EFL teachers with the required CALL materials development skills to enable them to be contributors to CALL…

  7. Computational Modeling and Experimental Characterization of Martensitic Transformations in Nicoal for Self-Sensing Materials

    Science.gov (United States)

    Wallace, T. A.; Yamakov, V. I.; Hochhalter, J. D.; Leser, W. P.; Warner, J. E.; Newman, J. A.; Purja Pun, G. P.; Mishin, Y.

    2015-01-01

    Fundamental changes to aero-vehicle management require the utilization of automated health monitoring of vehicle structural components. A novel method is the use of self-sensing materials, which contain embedded sensory particles (SP). SPs are micron-sized pieces of shape-memory alloy that undergo transformation when the local strain reaches a prescribed threshold. The transformation is a result of a spontaneous rearrangement of the atoms in the crystal lattice under intensified stress near damaged locations, generating acoustic waves of a specific spectrum that can be detected by a suitably placed sensor. The sensitivity of the method depends on the strength of the emitted signal and its propagation through the material. To study the transition behavior of the sensory particle inside a metal matrix under load, a simulation approach based on a coupled atomistic-continuum model is used. The simulation results indicate a strong dependence of the particle's pseudoelastic response on its crystallographic orientation with respect to the loading direction and suggest possible ways of optimizing particle sensitivity. The technology of embedded sensory particles will serve as the key element in an autonomous structural health monitoring system that will constantly monitor for damage initiation in service, which will enable quick detection of unforeseen damage initiation in real-time and during onground inspections.

  8. Eighteenth Workshop on Recent Developments in Computer Simulation Studies in Condensed Matter Physics

    CERN Document Server

    Landau, David P; Schüttler, Heinz-Bernd; Computer Simulation Studies in Condensed-Matter Physics XVIII

    2006-01-01

    This volume represents a "status report" emanating from presentations made during the 18th Annual Workshop on Computer Simulations Studies in Condensed Matter Physics at the Center for Simulational Physics at the University of Georgia in March 2005. It provides a broad overview of the most recent advances in the field, spanning the range from statistical physics to soft condensed matter and biological systems. Results on nanostructures and materials are included as are several descriptions of advances in quantum simulations and quantum computing as well as.methodological advances.

  9. Reduced material model for closed cell metal foam infiltrated with phase change material based on high resolution numerical studies

    International Nuclear Information System (INIS)

    Ohsenbrügge, Christoph; Marth, Wieland; Navarro y de Sosa, Iñaki; Drossel, Welf-Guntram; Voigt, Axel

    2016-01-01

    Highlights: • Closed cell metal foam sandwich structures were investigated. • High resolution numerical studies were conducted using CT scan data. • A reduced model for use in commercial FE software reduces needed degrees of freedom. • Thermal inertia is increased about 4 to 5 times in PCM filled structures. • The reduced material model was verified using experimental data. - Abstract: The thermal behaviour of closed cell metal foam infiltrated with paraffin wax as latent heat storage for application in high precision tool machines was examined. Aluminium foam sandwiches with metallically bound cover layers were prepared in a powder metallurgical process and cross-sectional images of the structures were generated with X-ray computed tomography. Based on the image data a three dimensional highly detailed model was derived and prepared for simulation with the adaptive FE-library AMDiS. The pores were assumed to be filled with paraffin wax. The thermal conductivity and the transient thermal behaviour in the phase-change region were investigated. Based on the results from the highly detailed simulations a reduced model for use in commercial FE-software (ANSYS) was derived. It incorporates the properties of the matrix and the phase change material into a homogenized material. A sandwich-structure with and without paraffin was investigated experimentally under constant thermal load. The results were used to verify the reduced material model in ANSYS.

  10. COMPUTING

    CERN Multimedia

    I. Fisk

    2011-01-01

    Introduction CMS distributed computing system performed well during the 2011 start-up. The events in 2011 have more pile-up and are more complex than last year; this results in longer reconstruction times and harder events to simulate. Significant increases in computing capacity were delivered in April for all computing tiers, and the utilisation and load is close to the planning predictions. All computing centre tiers performed their expected functionalities. Heavy-Ion Programme The CMS Heavy-Ion Programme had a very strong showing at the Quark Matter conference. A large number of analyses were shown. The dedicated heavy-ion reconstruction facility at the Vanderbilt Tier-2 is still involved in some commissioning activities, but is available for processing and analysis. Facilities and Infrastructure Operations Facility and Infrastructure operations have been active with operations and several important deployment tasks. Facilities participated in the testing and deployment of WMAgent and WorkQueue+Request...

  11. COMPUTING

    CERN Multimedia

    M. Kasemann

    Overview During the past three months activities were focused on data operations, testing and re-enforcing shift and operational procedures for data production and transfer, MC production and on user support. Planning of the computing resources in view of the new LHC calendar in ongoing. Two new task forces were created for supporting the integration work: Site Commissioning, which develops tools helping distributed sites to monitor job and data workflows, and Analysis Support, collecting the user experience and feedback during analysis activities and developing tools to increase efficiency. The development plan for DMWM for 2009/2011 was developed at the beginning of the year, based on the requirements from the Physics, Computing and Offline groups (see Offline section). The Computing management meeting at FermiLab on February 19th and 20th was an excellent opportunity discussing the impact and for addressing issues and solutions to the main challenges facing CMS computing. The lack of manpower is particul...

  12. Machinability studies of infrared window materials and metals

    International Nuclear Information System (INIS)

    Arnold, J.B.; Morris, T.O.; Sladky, R.E.; Steger, P.J.

    1976-01-01

    Diamond machining of materials for optical applications is becoming an important fabrication process. Development work in material-removal technology to better understand the mechanics of the diamond-turning process, its limitations, and applications is described. The technique is presently limited to a select group of metals, most of which are of a face-center-cubic crystal structure. Machinability studies were done which were designed to better understand diamond compatibility and thus expand the range of applicable materials. Nonconventional methods such as ultrasonic tool stimulation were investigated. Work done to determine the machinability of infrared window materials indicates that this is a viable fabrication technique for many materials, although additional effort is needed to optimize the process for particular materials

  13. Characterization study of industrial waste glass as starting material ...

    African Journals Online (AJOL)

    In present study, an industrial waste glass was characterized and the potential to assess as starting material in development of bioactive materials was investigated. A waste glass collected from the two different glass industry was grounded to fine powder. The samples were characterized using X-ray fluorescence (XRF), ...

  14. Moessbauer spectroscopic studies of magnetically ordered biological materials

    International Nuclear Information System (INIS)

    Dickson, D.P.E.

    1987-01-01

    This paper discusses recent work showing the application of Moessbauer spectroscopy to the study of the properties of the magnetically ordered materials which occur in a variety of biological systems. These materials display a diversity of behaviour which provides good examples of the various possibilities which can arise with iron-containing particles of different compositions and sizes. (orig.)

  15. Computer simulation of radiation-induced nanostructure formation in amorphous materials

    International Nuclear Information System (INIS)

    Li, K.-D.; Perez-Bergquist, Alejandro; Wang, Lumin

    2009-01-01

    In this study, 3D simulations based on a theoretical model were developed to investigate radiation-induced nanostructure formation in amorphous materials. Model variables include vacancy production and recombination rates, ion sputtering effects, and redeposition of sputtered atoms. In addition, a phase field model was developed to predict vacancy diffusion as a function of free energies of mixing and interfacial energies. The distribution profile of the vacancy production rate along the depth of an irradiated matrix was considered as a near Gaussian approximation according to Monte-Carlo TRIM code calculations. Dynamic processes responsible for nanostructure evolution were simulated by updating the vacancy concentration profile over time. Simulated morphologies include cellular nanoholes, nanowalls, nanovoids, and nanofibers, with the resultant morphology dependant upon the incident ion species and ion fluence. These simulated morphologies are consistent with experimental observations achieved under comparable experimental conditions. Our model provides a distinct numerical approach to accurately predicting morphological results for ion-irradiation-induced nanostructures.

  16. Algebraic computing program for studying the gauge theory

    International Nuclear Information System (INIS)

    Zet, G.

    2005-01-01

    An algebraic computing program running on Maple V platform is presented. The program is devoted to the study of the gauge theory with an internal Lie group as local symmetry. The physical quantities (gauge potentials, strength tensors, dual tensors etc.) are introduced either as equations in terms of previous defined quantities (tensors), or by manual entry of the component values. The components of the strength tensor and of its dual are obtained with respect to a given metric of the space-time used for describing the gauge theory. We choose a Minkowski space-time endowed with spherical symmetry and give some example of algebraic computing that are adequate for studying electroweak or gravitational interactions. The field equations are also obtained and their solutions are determined using the DEtools facilities of the Maple V computing program. (author)

  17. [A computer-aided image diagnosis and study system].

    Science.gov (United States)

    Li, Zhangyong; Xie, Zhengxiang

    2004-08-01

    The revolution in information processing, particularly the digitizing of medicine, has changed the medical study, work and management. This paper reports a method to design a system for computer-aided image diagnosis and study. Combined with some good idea of graph-text system and picture archives communicate system (PACS), the system was realized and used for "prescription through computer", "managing images" and "reading images under computer and helping the diagnosis". Also typical examples were constructed in a database and used to teach the beginners. The system was developed by the visual developing tools based on object oriented programming (OOP) and was carried into operation on the Windows 9X platform. The system possesses friendly man-machine interface.

  18. CRUSH1: a simplified computer program for impact analysis of radioactive material transport casks

    Energy Technology Data Exchange (ETDEWEB)

    Ikushima, Takeshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1996-07-01

    In drop impact analyses for radioactive transport casks, it has become possible to perform them in detail by using interaction evaluation, computer programs, such as DYNA2D, DYNA3D, PISCES and HONDO. However, the considerable cost and computer time are necessitated to perform analyses by these programs. To meet the above requirements, a simplified computer program CRUSH1 has been developed. The CRUSH1 is a static calculation computer program capable of evaluating the maximum acceleration of cask bodies and the maximum deformation of shock absorbers using an Uniaxial Displacement Method (UDM). The CRUSH1 is a revised version of the CRUSH. Main revisions of the computer program are as follows; (1) not only main frame computer but also work stations (OS UNIX) and personal computer (OS Windows 3.1 or Windows NT) are available for use of the CRUSH1 and (2) input data set are revised. In the paper, brief illustration of calculation method using UDM is presented. The second section presents comparisons between UDM and the detailed method. The third section provides a use`s guide for CRUSH1. (author)

  19. CRUSH1: a simplified computer program for impact analysis of radioactive material transport casks

    International Nuclear Information System (INIS)

    Ikushima, Takeshi

    1996-07-01

    In drop impact analyses for radioactive transport casks, it has become possible to perform them in detail by using interaction evaluation, computer programs, such as DYNA2D, DYNA3D, PISCES and HONDO. However, the considerable cost and computer time are necessitated to perform analyses by these programs. To meet the above requirements, a simplified computer program CRUSH1 has been developed. The CRUSH1 is a static calculation computer program capable of evaluating the maximum acceleration of cask bodies and the maximum deformation of shock absorbers using an Uniaxial Displacement Method (UDM). The CRUSH1 is a revised version of the CRUSH. Main revisions of the computer program are as follows; (1) not only main frame computer but also work stations (OS UNIX) and personal computer (OS Windows 3.1 or Windows NT) are available for use of the CRUSH1 and (2) input data set are revised. In the paper, brief illustration of calculation method using UDM is presented. The second section presents comparisons between UDM and the detailed method. The third section provides a use's guide for CRUSH1. (author)

  20. Computer Assisted Instruction in Special Education Three Case Studies

    Directory of Open Access Journals (Sweden)

    İbrahim DOĞAN

    2015-09-01

    Full Text Available The purpose of this study is to investigate the computer use of three students attending the special education center. Students have mental retardation, hearing problem and physical handicap respectively. The maximum variation sampling is used to select the type of handicap while the convenience sampling is used to select the participants. Three widely encountered handicap types in special education are chosen to select the study participants. The multiple holistic case study design is used in the study. Results of the study indicate that teachers in special education prefer to use educational games and drill and practice type of computers programs. Also it is found that over use of the animation, text and symbols cause cognitive overload on the student with mental retardation. Additionally, it is also discovered that the student with hearing problem learn words better when the computers are used in education as compared to the traditional method. Furthermore the student with physical handicap improved his fine muscle control abilities besides planned course objectives when computers are used in special education.

  1. Considering Materials Management in Construction: An Exploratory Study

    Directory of Open Access Journals (Sweden)

    Zakaria Dakhli

    2018-03-01

    Full Text Available While materials count for a considerable amount of construction costs, the way materials are managed seems to be improvised rather than approached methodically. This study investigates the practice of novel techniques used to manage materials in the construction industry. Techniques that have already proven themselves to be efficient ways to manage the production pace within the industry include the pull system, Just-In-Time, Kitting and off-site fabrication. These are explained and assessed in the context of the French construction industry through an exploratory study, supported by a questionnaire completed by contractors. The results reveal that a clear plan to manage materials on-site is lacking among the respondents, creating common inventory problems. This research provides evidence to support the central role played by an efficient management of material flow on-site. It also highlights the obstacles that hinder the adoption of innovative techniques, such as sub-contractor coordination.

  2. A Study on thermal-hydraulic characteristics of the coolant materials for the transmutation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Kim, Ju Youl; Kim, Do Hyoung; Kim, Yoon Ik; Yang, Hui Chang [Seoul National University, Taejon (Korea)

    1998-03-01

    The objective of this study is to provide the direction of transmutation reactor design in terms of thermal hydraulics especially through the analysis of thermal hydraulic characteristics of various candidate materials for the transmutation reactor coolant. In this study, the characteristics of coolant materials used in current nuclear power plants and candidate materials for transmutation reactor are analyzed and compared. To evaluate the thermal hydraulic characteristics, the preliminary thermal-hydraulic calculation is performed for the candidate coolant materials of transmutation reactor. An analysis of thermal-hydraulic characteristics of transmutation reactor. An analysis of thermal-hydraulic characteristics of Sodium, Lead, Lead-Bismuth, and Lead-Lithium among the liquid metals considered as the coolant of transmutation reactor is performed by using computational fluid dynamics code FLUENT, and SIMPLER algorithm. (author). 50 refs., 40 figs., 30 tabs.

  3. Computer Assisted Instruction in Special Education Three Case Studies

    OpenAIRE

    İbrahim DOĞAN; Ömür AKDEMİR

    2015-01-01

    The purpose of this study is to investigate the computer use of three students attending the special education center. Students have mental retardation, hearing problem and physical handicap respectively. The maximum variation sampling is used to select the type of handicap while the convenience sampling is used to select the participants. Three widely encountered handicap types in special education are chosen to select the study participants. The multiple holistic case study design is used i...

  4. Statistical study on the strength of structural materials and elements

    International Nuclear Information System (INIS)

    Blume, J.A.; Dalal, J.S.; Honda, K.K.

    1975-07-01

    Strength data for structural materials and elements including concrete, reinforcing steel, structural steel, plywood elements, reinforced concrete beams, reinforced concrete columns, brick masonry elements, and concrete masonry walls were statistically analyzed. Sample statistics were computed for these data, and distribution parameters were derived for normal, lognormal, and Weibull distributions. Goodness-of-fit tests were performed on these distributions. Most data, except those for masonry elements, displayed fairly small dispersion. Dispersion in data for structural materials was generally found to be smaller than for structural elements. Lognormal and Weibull distributions displayed better overall fits to data than normal distribution, although either Weibull or lognormal distribution can be used to represent the data analyzed. (auth)

  5. Body dynamics and hydrodynamics of swimming larvae: a computational study

    NARCIS (Netherlands)

    Li, G.; Müller, U.K.; Leeuwen, van J.L.; Liu, H.

    2012-01-01

    To understand the mechanics of fish swimming, we need to know the forces exerted by the fluid and how these forces affect the motion of the fish. To this end, we developed a 3-D computational approach that integrates hydrodynamics and body dynamics. This study quantifies the flow around a swimming

  6. Study on GPU Computing for SCOPE2 with CUDA

    International Nuclear Information System (INIS)

    Kodama, Yasuhiro; Tatsumi, Masahiro; Ohoka, Yasunori

    2011-01-01

    For improving safety and cost effectiveness of nuclear power plants, a core calculation code SCOPE2 has been developed, which adopts detailed calculation models such as the multi-group nodal SP3 transport calculation method in three-dimensional pin-by-pin geometry to achieve high predictability. However, it is difficult to apply the code to loading pattern optimizations since it requires much longer computation time than that of codes based on the nodal diffusion method which is widely used in core design calculations. In this study, we studied possibility of acceleration of SCOPE2 with GPU computing capability which has been recognized as one of the most promising direction of high performance computing. In the previous study with an experimental programming framework, it required much effort to convert the algorithms to ones which fit to GPU computation. It was found, however, that this conversion was tremendously difficult because of the complexity of algorithms and restrictions in implementation. In this study, to overcome this complexity, we utilized the CUDA programming environment provided by NVIDIA which is a versatile and flexible language as an extension to the C/C++ languages. It was confirmed that we could enjoy high performance without degradation of maintainability through test implementation of GPU kernels for neutron diffusion/simplified P3 equation solvers. (author)

  7. Integration of case study approach, project design and computer ...

    African Journals Online (AJOL)

    pc

    2018-03-05

    Mar 5, 2018 ... computer modeling used as a research method applied in the process ... conclusions discuss the benefits for students who analyzed the ... accounting education process the case study method should not .... providing travel safety information to passengers ... from literature readings with practical problems.

  8. SPECTROSCOPIC STUDIES OF MATERIALS FOR ELECTROCHEMICAL ENERGY STORAGE

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, Steven G.

    2014-03-01

    Several battery materials research projects were undertaken, suing NMR spectroscopy as a primary analytical tool. These include transport proerties of liquid and solid electrolytes and structural studies of Li ion electrodes.

  9. Hybrid Composite Material and Solid Particle Erosion Studies

    Science.gov (United States)

    Chellaganesh, D.; Khan, M. Adam; Ashif, A. Mohamed; Ragul Selvan, T.; Nachiappan, S.; Winowlin Jappes, J. T.

    2018-04-01

    Composite is one of the predominant material for most challenging engineering components. Most of the components are in the place of automobile structure, aircraft structures, and wind turbine blade and so on. At the same all the components are indulged to mechanical loading. Recent research on composite material are machinability, wear, tear and corrosion studies. One of the major issue on recent research was solid particle air jet erosion. In this paper hybrid composite material with and without filler. The fibre are in the combination of hemp – kevlar (60:40 wt.%) as reinforcement using epoxy as a matrix. The natural material palm and coconut shell are used as filler materials in the form of crushed powder. The process parameter involved are air jet velocity, volume of erodent and angle of impingement. Experiment performed are in eight different combinations followed from 2k (k = 3) factorial design. From the investigation surface morphology was studied using electron microscope. Mass change with respect to time are used to calculate wear rate and the influence of the process parameters. While solid particle erosion the hard particle impregnates in soft matrix material. Influence of filler material has reduced the wear and compared to plain natural composite material.

  10. Revisiting dibenzothiophene thermochemical data: Experimental and computational studies

    International Nuclear Information System (INIS)

    Freitas, Vera L.S.; Gomes, Jose R.B.; Ribeiro da Silva, Maria D.M.C.

    2009-01-01

    Thermochemical data of dibenzothiophene were studied in the present work by experimental techniques and computational calculations. The standard (p 0 =0.1MPa) molar enthalpy of formation, at T = 298.15 K, in the gaseous phase, was determined from the enthalpy of combustion and sublimation, obtained by rotating bomb calorimetry in oxygen, and by Calvet microcalorimetry, respectively. This value was compared with estimated data from G3(MP2)//B3LYP computations and also with the other results available in the literature.

  11. Electromagnetic computation methods for lightning surge protection studies

    CERN Document Server

    Baba, Yoshihiro

    2016-01-01

    This book is the first to consolidate current research and to examine the theories of electromagnetic computation methods in relation to lightning surge protection. The authors introduce and compare existing electromagnetic computation methods such as the method of moments (MOM), the partial element equivalent circuit (PEEC), the finite element method (FEM), the transmission-line modeling (TLM) method, and the finite-difference time-domain (FDTD) method. The application of FDTD method to lightning protection studies is a topic that has matured through many practical applications in the past decade, and the authors explain the derivation of Maxwell's equations required by the FDTD, and modeling of various electrical components needed in computing lightning electromagnetic fields and surges with the FDTD method. The book describes the application of FDTD method to current and emerging problems of lightning surge protection of continuously more complex installations, particularly in critical infrastructures of e...

  12. Quantitative description on structure-property relationships of Li-ion battery materials for high-throughput computations

    Science.gov (United States)

    Wang, Youwei; Zhang, Wenqing; Chen, Lidong; Shi, Siqi; Liu, Jianjun

    2017-12-01

    Li-ion batteries are a key technology for addressing the global challenge of clean renewable energy and environment pollution. Their contemporary applications, for portable electronic devices, electric vehicles, and large-scale power grids, stimulate the development of high-performance battery materials with high energy density, high power, good safety, and long lifetime. High-throughput calculations provide a practical strategy to discover new battery materials and optimize currently known material performances. Most cathode materials screened by the previous high-throughput calculations cannot meet the requirement of practical applications because only capacity, voltage and volume change of bulk were considered. It is important to include more structure-property relationships, such as point defects, surface and interface, doping and metal-mixture and nanosize effects, in high-throughput calculations. In this review, we established quantitative description of structure-property relationships in Li-ion battery materials by the intrinsic bulk parameters, which can be applied in future high-throughput calculations to screen Li-ion battery materials. Based on these parameterized structure-property relationships, a possible high-throughput computational screening flow path is proposed to obtain high-performance battery materials.

  13. Feasibility study--computerized application of the hazardous material regulations

    International Nuclear Information System (INIS)

    Ferrada, J.J.; Green, V.M.; Rawl, R.R.

    1992-09-01

    The feasibility of developing a full expert system for transportation and packaging of hazardous and radioactive materials was initiated within the framework of three subtasks: (1) analysis of commercial packages related to regulation scanning, (2) analysis of computer languages to develop the expert system, and (3) development of expert system prototypes. The strategy to develop the latter subtask was to first,develop modules to capture the knowledge of different areas of transportation and packaging and second, to analyze the feasibility of appending these different modules in one final full package. The individual modules development contemplated one prototype for transporting and packaging of radioactive material and another for transporting hazardous chemical materials. In the event that it is not feasible to link these two packages, the modules can always be used as stand-alone tools, or linked as a single package with some restrictions in their applicability. The work done during this fiscal year has focused on developing a prototype for transporting radioactive materials

  14. Quality assessment of microwave-vacuum dried material with the use of computer image analysis and neural model

    Science.gov (United States)

    Koszela, K.; OtrzÄ sek, J.; Zaborowicz, M.; Boniecki, P.; Mueller, W.; Raba, B.; Lewicki, A.; Przybył, K.

    2014-04-01

    The farming area for vegetables in Poland is constantly changed and modified. Each year the cultivation structure of particular vegetables is different. However, it is the cultivation of carrots that plays a significant role among vegetables. According to the Main Statistical Office (GUS), in 2012 carrot held second position among the cultivated root vegetables, and it was estimated at 835 thousand tons. In the world we are perceived as the leading producer of carrot, due to the fourth place in the ranking of global producers. Poland is the largest producer of this vegetable in the EU [1]. It is also noteworthy, that the demand for dried vegetables is still increasing. This tendency affects the development of drying industry in our country, contributing to utilization of the product surplus. Dried vegetables are used increasingly often in various sectors of food products industry, due to high nutrition value, as well as to changing alimentary preferences of consumers [2-3]. Dried carrot plays a crucial role among dried vegetables, because of its wide scope of use and high nutrition value. It contains a lot of carotene and sugar present in the form of crystals. Carrot also undergoes many different drying processes, which makes it difficult to perform a reliable quality assessment and classification of this dried material. One of many qualitative properties of dried carrot, having important influence on a positive or negative result of the quality assessment, is color and shape. The aim of the research project was to develop a method for the analysis of microwave-vacuum dried carrot images, and its application for the classification of individual fractions in the sample studied for quality assessment. During the research digital photographs of dried carrot were taken, which constituted the basis for assessment performed by a dedicated computer programme developed as a part of the research. Consequently, using a neural model, the dried material was classified [4-6].

  15. In-Service Design and Performance Prediction of Advanced Fusion Material Systems by Computational Modeling and Simulation

    International Nuclear Information System (INIS)

    G. R. Odette; G. E. Lucas

    2005-01-01

    This final report on ''In-Service Design and Performance Prediction of Advanced Fusion Material Systems by Computational Modeling and Simulation'' (DE-FG03-01ER54632) consists of a series of summaries of work that has been published, or presented at meetings, or both. It briefly describes results on the following topics: (1) A Transport and Fate Model for Helium and Helium Management; (2) Atomistic Studies of Point Defect Energetics, Dynamics and Interactions; (3) Multiscale Modeling of Fracture consisting of: (3a) A Micromechanical Model of the Master Curve (MC) Universal Fracture Toughness-Temperature Curve Relation, KJc(T - To), (3b) An Embrittlement DTo Prediction Model for the Irradiation Hardening Dominated Regime, (3c) Non-hardening Irradiation Assisted Thermal and Helium Embrittlement of 8Cr Tempered Martensitic Steels: Compilation and Analysis of Existing Data, (3d) A Model for the KJc(T) of a High Strength NFA MA957, (3e) Cracked Body Size and Geometry Effects of Measured and Effective Fracture Toughness-Model Based MC and To Evaluations of F82H and Eurofer 97, (3f) Size and Geometry Effects on the Effective Toughness of Cracked Fusion Structures; (4) Modeling the Multiscale Mechanics of Flow Localization-Ductility Loss in Irradiation Damaged BCC Alloys; and (5) A Universal Relation Between Indentation Hardness and True Stress-Strain Constitutive Behavior. Further details can be found in the cited references or presentations that generally can be accessed on the internet, or provided upon request to the authors. Finally, it is noted that this effort was integrated with our base program in fusion materials, also funded by the DOE OFES

  16. Computational Screening for Design of Optimal Coating Materials to Suppress Gas Evolution in Li-Ion Battery Cathodes.

    Science.gov (United States)

    Min, Kyoungmin; Seo, Seung-Woo; Choi, Byungjin; Park, Kwangjin; Cho, Eunseog

    2017-05-31

    Ni-rich layered oxides are attractive materials owing to their potentially high capacity for cathode applications. However, when used as cathodes in Li-ion batteries, they contain a large amount of Li residues, which degrade the electrochemical properties because they are the source of gas generation inside the battery. Here, we propose a computational approach to designing optimal coating materials that prevent gas evolution by removing residual Li from the surface of the battery cathode. To discover promising coating materials, the reactions of 16 metal phosphates (MPs) and 45 metal oxides (MOs) with the Li residues, LiOH, and Li 2 CO 3 are examined within a thermodynamic framework. A materials database is constructed according to density functional theory using a hybrid functional, and the reaction products are obtained according to the phases in thermodynamic equilibrium in the phase diagram. In addition, the gravimetric efficiency is calculated to identify coating materials that can eliminate Li residues with a minimal weight of the coating material. Overall, more MP and MO materials react with LiOH than with Li 2 CO 3 . Specifically, MPs exhibit better reactivity to both Li residues, whereas MOs react more with LiOH. The reaction products, such as Li-containing phosphates or oxides, are also obtained to identify the phases on the surface of a cathode after coating. On the basis of the Pareto-front analysis, P 2 O 5 could be an optimal material for the reaction with both Li residuals. Finally, the reactivity of the coating materials containing 3d/4d transition metal elements is better than that of materials containing other types of elements.

  17. COMPUTING

    CERN Multimedia

    I. Fisk

    2010-01-01

    Introduction It has been a very active quarter in Computing with interesting progress in all areas. The activity level at the computing facilities, driven by both organised processing from data operations and user analysis, has been steadily increasing. The large-scale production of simulated events that has been progressing throughout the fall is wrapping-up and reprocessing with pile-up will continue. A large reprocessing of all the proton-proton data has just been released and another will follow shortly. The number of analysis jobs by users each day, that was already hitting the computing model expectations at the time of ICHEP, is now 33% higher. We are expecting a busy holiday break to ensure samples are ready in time for the winter conferences. Heavy Ion An activity that is still in progress is computing for the heavy-ion program. The heavy-ion events are collected without zero suppression, so the event size is much large at roughly 11 MB per event of RAW. The central collisions are more complex and...

  18. COMPUTING

    CERN Multimedia

    M. Kasemann P. McBride Edited by M-C. Sawley with contributions from: P. Kreuzer D. Bonacorsi S. Belforte F. Wuerthwein L. Bauerdick K. Lassila-Perini M-C. Sawley

    Introduction More than seventy CMS collaborators attended the Computing and Offline Workshop in San Diego, California, April 20-24th to discuss the state of readiness of software and computing for collisions. Focus and priority were given to preparations for data taking and providing room for ample dialog between groups involved in Commissioning, Data Operations, Analysis and MC Production. Throughout the workshop, aspects of software, operating procedures and issues addressing all parts of the computing model were discussed. Plans for the CMS participation in STEP’09, the combined scale testing for all four experiments due in June 2009, were refined. The article in CMS Times by Frank Wuerthwein gave a good recap of the highly collaborative atmosphere of the workshop. Many thanks to UCSD and to the organizers for taking care of this workshop, which resulted in a long list of action items and was definitely a success. A considerable amount of effort and care is invested in the estimate of the comput...

  19. Understanding initial undergraduate expectations and identity in computing studies

    Science.gov (United States)

    Kinnunen, Päivi; Butler, Matthew; Morgan, Michael; Nylen, Aletta; Peters, Anne-Kathrin; Sinclair, Jane; Kalvala, Sara; Pesonen, Erkki

    2018-03-01

    There is growing appreciation of the importance of understanding the student perspective in Higher Education (HE) at both institutional and international levels. This is particularly important in Science, Technology, Engineering and Mathematics subjects such as Computer Science (CS) and Engineering in which industry needs are high but so are student dropout rates. An important factor to consider is the management of students' initial expectations of university study and career. This paper reports on a study of CS first-year students' expectations across three European countries using qualitative data from student surveys and essays. Expectation is examined from both short-term (topics to be studied) and long-term (career goals) perspectives. Tackling these issues will help paint a picture of computing education through students' eyes and explore their vision of its and their role in society. It will also help educators prepare students more effectively for university study and to improve the student experience.

  20. Identifying a Computer Forensics Expert: A Study to Measure the Characteristics of Forensic Computer Examiners

    Directory of Open Access Journals (Sweden)

    Gregory H. Carlton

    2010-03-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 The usage of digital evidence from electronic devices has been rapidly expanding within litigation, and along with this increased usage, the reliance upon forensic computer examiners to acquire, analyze, and report upon this evidence is also rapidly growing. This growing demand for forensic computer examiners raises questions concerning the selection of individuals qualified to perform this work. While courts have mechanisms for qualifying witnesses that provide testimony based on scientific data, such as digital data, the qualifying criteria covers a wide variety of characteristics including, education, experience, training, professional certifications, or other special skills. In this study, we compare task performance responses from forensic computer examiners with an expert review panel and measure the relationship with the characteristics of the examiners to their quality responses. The results of this analysis provide insight into identifying forensic computer examiners that provide high-quality responses. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

  1. Study of the factors affecting radon diffusion through building materials

    International Nuclear Information System (INIS)

    Chauhan, R.P.

    2011-01-01

    Radon appears mainly by diffusion processes from the point of origin following - decay of 226 Ra in underground soil and building materials used, in the construction of floors, walls, and ceilings. The diffusion of radon in dwellings is a process determined by the radon concentration gradient across the building material structure and can be a significant contributor to indoor radon inflow. Radon can originate from the deeply buried deposit beneath homes and can migrate to the surface of earth. Radon diffusion and transport through different media is a complex process and is affected by several factors. It is well known that for building construction materials the porosity, permeability and the diffusion coefficient are the parameters, which can quantify the materials capability to hinder the flow of radon soil gas. An increase in porosity will provide more air space within the material for radon to travel, thus reducing its resistance to radon transport. The permeability of material describes its ability to act as a barrier to gas movement when a pressure gradient exists across it and is closely related to the porosity of material. The radon diffusion coefficient of a material quantifies the ability of radon gas to move through it when a concentration gradient is the driving force. This parameter depends upon the porosity and permeability of the medium. As diffusion process is the major contributor to indoor levels, therefore, the factors affecting the diffusion process need to be kept in consideration. Keeping this in mind the experimental arrangements have been made for control study of radon diffusion through some building materials to observe the effects of different factors viz.; compaction, grain size, temperature, humidity and the mixing of these materials etc. For the present study alpha sensitive LR-115 type II solid-state nuclear track detectors (SSNTDs) have been used for the recording of alpha tracks caused by radon gas after its diffusion through the

  2. Theoretical studies of boron(III) complexes for the new blue luminescent material

    International Nuclear Information System (INIS)

    Lee, Jung Eun; Choi, Gyu Chul; Rim, Byung O.; Kim, Sung Min; Park, No Gill; Ha, Yun Kyoung; Kim, Young Sik

    2004-01-01

    Boron(III) complexes, BPh 2 (2-py-aza) and Bph 2 (2-py-in), are known as blue emitting materials. In this paper, we have studied various ligand effects of boron complex on the absorption (UV) and electroluminescence (EL) peaks computationally. To obtain optical properties, TD-DFT(B3LYP) methods are used with 6-31+G(d) basis set. It was found that EL peaks of those materials are calculated at 454 and 510 nm, which are considerably consistent with experimental data. From the results, we newly proposed two materials, BPh 2 (PBI-Me) and BPh 2 (PBI-Ph), as blue luminescent materials, whose calculated EL peaks are at 456 and 480 nm, respectively. Through the calculation results, newly designed compounds showed possibility as efficient and promising emitters in EL device

  3. CFD Vision 2030 Study: A Path to Revolutionary Computational Aerosciences

    Science.gov (United States)

    Slotnick, Jeffrey; Khodadoust, Abdollah; Alonso, Juan; Darmofal, David; Gropp, William; Lurie, Elizabeth; Mavriplis, Dimitri

    2014-01-01

    This report documents the results of a study to address the long range, strategic planning required by NASA's Revolutionary Computational Aerosciences (RCA) program in the area of computational fluid dynamics (CFD), including future software and hardware requirements for High Performance Computing (HPC). Specifically, the "Vision 2030" CFD study is to provide a knowledge-based forecast of the future computational capabilities required for turbulent, transitional, and reacting flow simulations across a broad Mach number regime, and to lay the foundation for the development of a future framework and/or environment where physics-based, accurate predictions of complex turbulent flows, including flow separation, can be accomplished routinely and efficiently in cooperation with other physics-based simulations to enable multi-physics analysis and design. Specific technical requirements from the aerospace industrial and scientific communities were obtained to determine critical capability gaps, anticipated technical challenges, and impediments to achieving the target CFD capability in 2030. A preliminary development plan and roadmap were created to help focus investments in technology development to help achieve the CFD vision in 2030.

  4. Si K-edge XANES study of SiOxCyHz amorphous polymeric materials

    International Nuclear Information System (INIS)

    Chaboy, J.; Barranco, A.; Yanguas-Gil, A.; Yubero, F.; Gonzalez-Elipe, A. R.

    2007-01-01

    This work reports on x-ray absorption spectroscopy study at the Si K edge of several amorphous SiO x C y H z polymers prepared by plasma-enhanced chemical-vapor deposition with different C/O ratios. SiO 2 and SiC have been used as reference materials. The comparison of the experimental Si K-edge x-ray absorption near-edge structure spectra with theoretical computations based on multiple scattering theory has allowed us to monitor the modification of the local coordination around Si as a function of the overall C/O ratio in this kind of materials

  5. A practical material decomposition method for x-ray dual spectral computed tomography.

    Science.gov (United States)

    Hu, Jingjing; Zhao, Xing

    2016-03-17

    X-ray dual spectral CT (DSCT) scans the measured object with two different x-ray spectra, and the acquired rawdata can be used to perform the material decomposition of the object. Direct calibration methods allow a faster material decomposition for DSCT and can be separated in two groups: image-based and rawdata-based. The image-based method is an approximative method, and beam hardening artifacts remain in the resulting material-selective images. The rawdata-based method generally obtains better image quality than the image-based method, but this method requires geometrically consistent rawdata. However, today's clinical dual energy CT scanners usually measure different rays for different energy spectra and acquire geometrically inconsistent rawdata sets, and thus cannot meet the requirement. This paper proposes a practical material decomposition method to perform rawdata-based material decomposition in the case of inconsistent measurement. This method first yields the desired consistent rawdata sets from the measured inconsistent rawdata sets, and then employs rawdata-based technique to perform material decomposition and reconstruct material-selective images. The proposed method was evaluated by use of simulated FORBILD thorax phantom rawdata and dental CT rawdata, and simulation results indicate that this method can produce highly quantitative DSCT images in the case of inconsistent DSCT measurements.

  6. Neutron spectra calculation in material in order to compute irradiation damage

    International Nuclear Information System (INIS)

    Dupont, C.; Gonnord, J.; Le Dieu de Ville, A.; Nimal, J.C.; Totth, B.

    1982-01-01

    This short presentation will be on neutron spectra calculation methods in order to compute the damage rate formation in irradiated structure. Three computation schemes are used in the French C.E.A.: (1) 3-dimensional calculations using the line of sight attenuation method (MERCURE IV code), the removal cross section being obtained from an adjustment on a 1-dimensional transport calculation with the discrete ordinate code ANISN; (2) 2-dimensional calculations using the discrete ordinates method (DOT 3.5 code), 20 to 30 group library obtained by collapsing the 100 group a library on fluxes computed by ANISN; (3) 3-dimensional calculations using the Monte Carlo method (TRIPOLI system). The cross sections which originally came from UKNDL 73 and ENDF/B3 are now processed from ENDF B IV. (author)

  7. From pattern formation to material computation multi-agent modelling of physarum polycephalum

    CERN Document Server

    Jones, Jeff

    2015-01-01

    This book addresses topics of mobile multi-agent systems, pattern formation, biological modelling, artificial life, unconventional computation, and robotics. The behaviour of a simple organism which is capable of remarkable biological and computational feats that seem to transcend its simple component parts is examined and modelled. In this book the following question is asked: How can something as simple as Physarum polycephalum - a giant amoeboid single-celled organism which does not possess any neural tissue, fixed skeleton or organised musculature - can approximate complex computational behaviour during its foraging, growth and adaptation of its amorphous body plan, and with such limited resources? To answer this question the same apparent limitations as faced by the organism are applied: using only simple components with local interactions. A synthesis approach is adopted and a mobile multi-agent system with very simple individual behaviours is employed. It is shown their interactions yield emergent beha...

  8. Positron annihilation studies on structural materials for nuclear reactors

    International Nuclear Information System (INIS)

    Rajaraman, R.; Amarendra, G.; Sundar, C.S.

    2012-01-01

    Structural steels for nuclear reactors have renewed interest owing to the future advanced fission reactor design with increased burn-up goals as well as for fusion reactor applications. While modified austenitic steels continue to be the main cladding materials for fast breeder reactors, Ferritic/martensitic steels and oxide dispersion strengthened ferritic steels are the candidate materials for future reactors applications in India. Sensitivity and selectivity of positron annihilation spectroscopy to open volume type defects and nano clusters have been extensively utilized in studying reactor materials. We have recently reviewed the application of positron techniques to reactor structural steels. In this talk, we will present successful application of positron annihilation spectroscopy to probe various structural materials such as D9, ferritic/martensitic, oxide dispersion strengthened (ODS) steels and related model alloys, highlighting our recent studies. (author)

  9. Implications of fusion power plant studies for materials requirements

    International Nuclear Information System (INIS)

    Cook, Ian; Ward, David; Dudarev, Sergei

    2002-01-01

    This paper addresses the key requirements for fusion materials, as these have emerged from studies of commercial fusion power plants. The objective of the international fusion programme is the creation of power stations that will have very attractive safety and environmental features and viable economics. Fusion power plant studies have shown that these objectives may be achieved without requiring extreme advances in materials. But it is required that existing candidate materials perform at least as well as envisaged in the environment of fusion neutrons, heat fluxes and particle fluxes. The development of advanced materials would bring further benefits. The work required entails the investigation of many intellectually exciting physics issues of great scientific interest, and of wider application than fusion. In addition to giving an overview, selected aspects of the science, of particular physics interest, are illustrated

  10. A study of visual and musculoskeletal health disorders among computer professionals in NCR Delhi

    Directory of Open Access Journals (Sweden)

    Talwar Richa

    2009-01-01

    Full Text Available Objective: To study the prevalence of health disorders among computer professionals and its association with working environment conditions. Study design: Cross sectional. Materials and Methods: A sample size of 200 computer professionals, from Delhi and NCR which included software developers, call centre workers, and data entry workers. Result: The prevalence of visual problems in the study group was 76% (152/200, and musculoskeletal problems were reported by 76.5% (153/200. It was found that there was a gradual increase in visual complaints as the number of hours spent for working on computers daily increased and the same relation was found to be true for musculoskeletal problems as well. Visual problems were less in persons using antiglare screen, and those with adequate lighting in the room. Musculoskeletal problems were found to be significantly lesser among those using cushioned chairs and soft keypad. Conclusion: A significant proportion of the computer professionals were found to be having health problems and this denotes that the occupational health of the people working in the computer field needs to be emphasized as a field of concern in occupational health.

  11. NATO Advanced Study Institute on Methods in Computational Molecular Physics

    CERN Document Server

    Diercksen, Geerd

    1992-01-01

    This volume records the lectures given at a NATO Advanced Study Institute on Methods in Computational Molecular Physics held in Bad Windsheim, Germany, from 22nd July until 2nd. August, 1991. This NATO Advanced Study Institute sought to bridge the quite considerable gap which exist between the presentation of molecular electronic structure theory found in contemporary monographs such as, for example, McWeeny's Methods 0/ Molecular Quantum Mechanics (Academic Press, London, 1989) or Wilson's Electron correlation in moleeules (Clarendon Press, Oxford, 1984) and the realization of the sophisticated computational algorithms required for their practical application. It sought to underline the relation between the electronic structure problem and the study of nuc1ear motion. Software for performing molecular electronic structure calculations is now being applied in an increasingly wide range of fields in both the academic and the commercial sectors. Numerous applications are reported in areas as diverse as catalysi...

  12. Decoding Computer Games: Studying “Special Operation 85”

    Directory of Open Access Journals (Sweden)

    Bahareh Jalalzadeh

    2009-11-01

    Full Text Available As other media, computer games convey messages which have tow features: explicit and implicit. Semiologically studying computer games and comparing them with narrative structures, the present study attempts to discover the messages they convey. Therefore we have studied and decoded “Special operation 85” as a semiological text. Results show that the game’s features, as naming, interests and motivations of the engaged people, and the events narrated, all lead the producers to their goals of introducing and publicizing Iranian-Islamic cultural values. Although this feature makes “Special Opreation 85” a unique game, it fails in its attempt to produce a mythical personage in Iranian-Islamic cultural context.

  13. Evaluation of the hemodynamic effects of intravenous administration of ionic and nonionic contrast materials: implications for deriving physiologic measurements from computed tomography and digital cardiovascular imaging

    International Nuclear Information System (INIS)

    Higgins, C.B.; Berber, K.H.; Mattrey, R.F.; Slutsky, R.A.

    1982-01-01

    The effects of intravenous injection of an ionic contrast material (Renografin-76 [meglumine sodium diatrizoate]) on left ventricular pressure, internal diameter, and wall thickness, and on coronary and femoral hemodynamics were compared with those of a hydrolytically stable nonionic contrast material (iohexol). Renografin-76 caused drastic biphasic changes in left ventricular pressure and dp/dt (rate of change of left ventricular pressure), and moderate changes in end systolic dimension. Iohexol caused little or no change in left ventricular pressure and dimensions. In addition, Renografin-76 caused marked arterial hypotension and large increases in coronary and femoral blood lows, while iohexol caused no significant change in arterial pressure and coronary blood flow, and a mild increase in femoral blood flow. Based on these findings, it is concluded that iohexol is preferable to standard ionic contrast material for deriving basal physiologic information from computed tomographic and digital vascular studies

  14. Computer simulations of rare earth sites in glass: experimental tests and applications to laser materials

    International Nuclear Information System (INIS)

    Weber, M.J.

    1984-11-01

    Computer simulations of the microscopic structure of BeF 2 glasses using molecular dynamics are reviewed and compared with x-ray and neutron diffraction, EXAFS, NMR, and optical measurements. Unique information about the site-to-site variations in the local environments of rare earth ions is obtained using optical selective excitation and laser-induced fluorescence line-narrowing techniques. Applications and limitations of computer simulations to the development of laser glasses and to predictions of other static and dynamic properties of glasses are discussed. 35 references, 2 figures, 2 tables

  15. Phase-contrast x-ray computed tomography for observing biological specimens and organic materials

    Science.gov (United States)

    Momose, Atsushi; Takeda, Tohoru; Itai, Yuji

    1995-02-01

    A novel three-dimensional x-ray imaging method has been developed by combining a phase-contrast x-ray imaging technique with x-ray computed tomography. This phase-contrast x-ray computed tomography (PCX-CT) provides sectional images of organic specimens that would produce absorption-contrast x-ray CT images with little contrast. Comparing PCX-CT images of rat cerebellum and cancerous rabbit liver specimens with corresponding absorption-contrast CT images shows that PCX-CT is much more sensitive to the internal structure of organic specimens.

  16. Linking process and structure in the friction stir scribe joining of dissimilar materials: A computational approach with experimental support

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Varun; Upadhyay, Piyush; Fifield, Leonard S.; Roosendaal, Timothy; Sun, Xin; Nelaturu, Phalgun; Carlson, Blair

    2018-04-01

    The friction stir welding (FSW) is a popular technique to join dissimilar materials in numerous applications. The solid state nature of the process enables joining materials with strikingly different physical properties. For the welds in lap configuration, an enhancement to this technology is made by introducing a short hard insert, referred to as cutting-scribe, at the bottom of the tool pin. The cutting-scribe induces deformation in the bottom plate which leads to the formation of mechanical interlocks or hook like structures at the interface of two materials. A thermo-mechanically coupled computational model employing coupled Eulerian-Lagrangian approach is developed to quantitatively capture the morphology of these interlocks during the FSW process. The simulations using developed model are validated by the experimental observations.The identified interface morphology coupled with the predicted temperature field from this process-structure model can then be used to estimate the post-weld microstructure and joint strength.

  17. Computational and experimental studies of hydrodynamic instabilities and turbulent mixing (Review of NVIIEF efforts)

    International Nuclear Information System (INIS)

    Andronov, V.A.; Zhidov, I.G.; Meskov, E.E.; Nevmerzhitskii, N.V.; Nikiforov, V.V.; Razin, A.N.; Rogatchev, V.G.; Tolshmyakov, A.I.; Yanilkin, Yu.V.

    1995-02-01

    This report describes an extensive program of investigations conducted at Arzamas-16 in Russia over the past several decades. The focus of the work is on material interface instability and the mixing of two materials. Part 1 of the report discusses analytical and computational studies of hydrodynamic instabilities and turbulent mixing. The EGAK codes are described and results are illustrated for several types of unstable flow. Semiempirical turbulence transport equations are derived for the mixing of two materials, and their capabilities are illustrated for several examples. Part 2 discusses the experimental studies that have been performed to investigate instabilities and turbulent mixing. Shock-tube and jelly techniques are described in considerable detail. Results are presented for many circumstances and configurations

  18. Effects of calibration methods on quantitative material decomposition in photon-counting spectral computed tomography using a maximum a posteriori estimator.

    Science.gov (United States)

    Curtis, Tyler E; Roeder, Ryan K

    2017-10-01

    Advances in photon-counting detectors have enabled quantitative material decomposition using multi-energy or spectral computed tomography (CT). Supervised methods for material decomposition utilize an estimated attenuation for each material of interest at each photon energy level, which must be calibrated based upon calculated or measured values for known compositions. Measurements using a calibration phantom can advantageously account for system-specific noise, but the effect of calibration methods on the material basis matrix and subsequent quantitative material decomposition has not been experimentally investigated. Therefore, the objective of this study was to investigate the influence of the range and number of contrast agent concentrations within a modular calibration phantom on the accuracy of quantitative material decomposition in the image domain. Gadolinium was chosen as a model contrast agent in imaging phantoms, which also contained bone tissue and water as negative controls. The maximum gadolinium concentration (30, 60, and 90 mM) and total number of concentrations (2, 4, and 7) were independently varied to systematically investigate effects of the material basis matrix and scaling factor calibration on the quantitative (root mean squared error, RMSE) and spatial (sensitivity and specificity) accuracy of material decomposition. Images of calibration and sample phantoms were acquired using a commercially available photon-counting spectral micro-CT system with five energy bins selected to normalize photon counts and leverage the contrast agent k-edge. Material decomposition of gadolinium, calcium, and water was performed for each calibration method using a maximum a posteriori estimator. Both the quantitative and spatial accuracy of material decomposition were most improved by using an increased maximum gadolinium concentration (range) in the basis matrix calibration; the effects of using a greater number of concentrations were relatively small in

  19. MicroShield 6.20 computations to evaluate dose rate in unprotected materials

    International Nuclear Information System (INIS)

    Slaveikova, M.; Stanev, I.

    2013-01-01

    An analysis of compliance with the requirement of Art. 36 of the Regulation on the conditions and procedure of transport of radioactive material is made.This analysis is carried out in connection with the construction of sites for temporary storage of radioactive materials and radioactive wastes from decommissioning activities of the Kozloduy NPP units 1-4. The aim is to assess the dose in unprotected materials. An analysis of the conformity with the requirements of the Bulgarian legislation to assess the dose rate of material in the absence of physical or other barriers. Many calculations are carried out to assess the dose rate around a piece of metal from the dismantling of the primary circuit, which is conservatively assumed that contamination is greatest

  20. MAT-FLX: a simplified code for computing material balances in fuel cycle

    International Nuclear Information System (INIS)

    Pierantoni, F.; Piacentini, F.

    1983-01-01

    This work illustrates a calculation code designed to provide a materials balance for the electro nuclear fuel cycle. The calculation method is simplified but relatively precise and employs a progressive tabulated data approach