Sample records for materials computational studies

  1. Experimental and Analytical Studies for a Computational Materials Program (United States)

    Knauss, W. G.


    The studies supported by Grant NAG1-1780 were directed at providing physical data on polymer behavior that would form the basis for computationally modeling these types of materials. Because of ongoing work in polymer characterization this grant supported part of a larger picture in this regard. Efforts went into two combined areas of their time dependent mechanical response characteristics: Creep properties on the one hand, subject to different volumetric changes (nonlinearly viscoelastic behavior) and time or frequency dependence of dilatational material behavior. The details of these endeavors are outlined sufficiently in the two appended publications, so that no further description of the effort is necessary.

  2. Computational study of porous materials for gas separations (United States)

    Lin, Li-Chiang

    Nanoporous materials such as zeolites, zeolitic imidazolate frameworks (ZIFs), and metal-organic frameworks (MOFs) are used as sorbents or membranes for gas separations such as carbon dioxide capture, methane capture, paraffin/olefin separations, etc. The total number of nanoporous materials is large; by changing the chemical composition and/or the structural topologies we can envision an infinite number of possible materials. In practice one can synthesize and fully characterize only a small subset of these materials. Hence, computational study can play an important role by utilizing various techniques in molecular simulations as well as quantum chemical calculations to accelerate the search for optimal materials for various energy-related separations. Accordingly, several large-scale computational screenings of over one hundred thousand materials have been performed to find the best materials for carbon capture, methane capture, and ethane/ethene separation. These large-scale screenings identified a number of promising materials for different applications. Moreover, the analysis of these screening studies yielded insights into those molecular characteristics of a material that contribute to an optimal performance for a given application. These insights provided useful guidelines for future structural design and synthesis. For instance, one of the screening studies indicated that some zeolite structures can potentially reduce the energy penalty imposed on a coal-fired power plant by as much as 35% compared to the near-term MEA technology for carbon capture application. These optimal structures have topologies with a maximized density of pockets and they capture and release CO2 molecules with an optimal energy. These screening studies also pointed to some systems, for which conventional force fields were unable to make sufficiently reliable predictions of the adsorption isotherms of different gasses, e.g., CO2 in MOFs with open-metal sites. For these systems, we

  3. Microstructural and Computer Simulation Studies on Some EFP Materials (United States)

    Pappu, Sridhar


    Explosively Formed Penetrators (EFPs) are self-forming ballistic projectiles deriving their energy from the detonation of a high explosive. As they form in-flight, strains up to 3 are reached at strain rates of about 10^4 per second, resulting in extreme deformation related changes in microstructure. In this study, we report microstructural features of three different EFP materials in an effort to understand the underlying mechanism behind EFP formation. The materials studied are Cu, Fe and Ta and represent different crystal structures and widely differing melting temperatures, properties that seem to play a significant role in microstructural evolution during the EFP formation process. Computer simulations using AUTODYN 2D software program will be carried out and the generated temperature and stress contours will be correlated with the observed microstructural features and measured microhardness data along the EFP half-section. This would help validate the hydrocodes and give useful insight into the unobservable part of the EFP formation process. Such a correlation of experimental and mathematical models would not only help understand the mechanism behind this process but also help design more effective projectiles without carrying out expensive experimental tests.

  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 ... analysis of individual flows of computer from the material flow model showed that the fate of obsolete computer equipment ...... Design Initiative Technical Report #97-10.

  5. Using defects to store energy in materials - a computational study. (United States)

    Lu, I-Te; Bernardi, Marco


    Energy storage occurs in a variety of physical and chemical processes. In particular, defects in materials can be regarded as energy storage units since they are long-lived and require energy to be formed. Here, we investigate energy storage in non-equilibrium populations of materials defects, such as those generated by bombardment or irradiation. We first estimate upper limits and trends for energy storage using defects. First-principles calculations are then employed to compute the stored energy in the most promising elemental materials, including tungsten, silicon, graphite, diamond and graphene, for point defects such as vacancies, interstitials and Frenkel pairs. We find that defect concentrations achievable experimentally (~0.1-1 at.%) can store large energies per volume and weight, up to ~5 MJ/L and 1.5 MJ/kg for covalent materials. Engineering challenges and proof-of-concept devices for storing and releasing energy with defects are discussed. Our work demonstrates the potential of storing energy using defects in materials.

  6. Computational study of interfaces and edges of 2D materials

    NARCIS (Netherlands)

    Farmanbar Gelepordsari, M.


    The discovery of graphene and its intriguing properties has given birth to the field of two-dimensional (2D) materials. These materials are characterized by a strong covalent bonding between the atoms within a plane, but weak, van derWaals, bonding between the planes. Such materials can be isolated

  7. Computational Study of Porous Materials for Gas Separations


    Lin, Li-Chiang


    Nanoporous materials such as zeolites, zeolitic imidazolate frameworks (ZIFs), and metal-organic frameworks (MOFs) are used as sorbents or membranes for gas separations such as carbon dioxide capture, methane capture, paraffin/olefin separations, etc. The total number of nanoporous materials is large; by changing the chemical composition and/or the structural topologies we can envision an infinite number of possible materials. In practice one can synthesize and fully characterize only a small...

  8. Computational studies of bioceramic crystals and related materials (United States)

    Rulis, Paul Michael

    Ongoing research to improve the foundations of knowledge concerning the human body requires a detailed understanding of the effects derived from atomic interactions. The details of these fundamental interactions will pave the way to the effective manipulation of macroscopic tissue. As a small step towards the realization of that goal the Orthogonalized Linear Combination of Atomic Orbitals (OLCAO) program suite has been applied to complex bioceramic crystals and other prototypes of hard tissue biological nanostructures. In addition, the OLCAO program suite has been further developed and extended in terms of efficiency, features, ease of use, and ease of maintenance such that even more complex systems and effects can be treated in the future. Through extensive OLCAO ab initio calculations on a collection of prototype bioceramic crystals the differences between them in terms of bonding, charge transfer, electronic structure, and spectroscopic properties have been detailed in an effort to lay the foundations of further research where interfaces, dopants, and defects are considered. In addition, inactive silicon defects that can be considered as prototypes for the complex environment in which bioceramic apatites exist have also been studied with the OLCAO program suite in an effort to expand the detection limit of small structures through spectroscopic means. With much effort, the OLCAO program suite has undergone a detailed conversion to a more modern programming language and programming style. A thorough review of the source code has accounted for many inaccuracies, corrected some programming errors, and removed various inefficient algorithmic bottlenecks. The generation of OLCAO input files, the execution of the components of the OLCAO suite, and the analysis of resultant data has been automated with numerous control scripts. Various external library packages have been instrumented for the benefit of profiling and resource efficiency in a high performance computing

  9. EDITORIAL: Computational materials science Computational materials science (United States)

    Kahl, Gerhard; Kresse, Georg


    Special issue in honour of Jürgen Hafner On 30 September 2010, Jürgen Hafner, one of the most prominent and influential members within the solid state community, retired. His remarkably broad scientific oeuvre has made him one of the founding fathers of modern computational materials science: more than 600 scientific publications, numerous contributions to books, and a highly cited monograph, which has become a standard reference in the theory of metals, witness not only the remarkable productivity of Jürgen Hafner but also his impact in theoretical solid state physics. In an effort to duly acknowledge Jürgen Hafner's lasting impact in this field, a Festsymposium was held on 27-29 September 2010 at the Universität Wien. The organizers of this symposium (and authors of this editorial) are proud to say that a large number of highly renowned scientists in theoretical condensed matter theory—co-workers, friends and students—accepted the invitation to this celebration of Hafner's jubilee. Some of these speakers also followed our invitation to submit their contribution to this Festschrift, published in Journal of Physics: Condensed Matter, a journal which Jürgen Hafner served in 2000-2003 and 2003-2006 as a member of the Advisory Editorial Board and member of the Executive Board, respectively. In the subsequent article, Volker Heine, friend and co-worker of Jürgen Hafner over many decades, gives an account of Hafner's impact in the field of theoretical condensed matter physics. Computational materials science contents Theoretical study of structural, mechanical and spectroscopic properties of boehmite (γ-AlOOH) D Tunega, H Pašalić, M H Gerzabek and H Lischka Ethylene epoxidation catalyzed by chlorine-promoted silver oxide M O Ozbek, I Onal and R A Van Santen First-principles study of Cu2ZnSnS4 and the related band offsets for photovoltaic applicationsA Nagoya, R Asahi and G Kresse Renormalization group study of random quantum magnetsIstván A Kovács and

  10. The Computational Materials Repository

    DEFF Research Database (Denmark)

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


    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...

  11. CO 2 sorption on substituted carbon materials . Computational chemistry studies (United States)

    Gauden, P. A.; Wiśniewski, M.


    Theoretical study of sorption of CO 2 on the 4-ring graphene ("unmodified" or N-, O-, and OH-substituted) structures possessing one completely unsaturated edge zigzag site is reported using the DFT (B3LYP/6-31G(d,p)) method. Lactone and heterocyclic complexes (due to thermodynamic favourability) are taken into account. The analysis of theoretical results shows that the enthalpy of reaction strongly depends on the chemical nature, i.e. the position of the doping of atom(s) is crucial. All substitutions do not change or decrease the enthalpy in comparison with the "unmodified" graphene sheet. The well-known theoretical reactivity indices (ionization potential, electron affinity, global softness, and HOMO-LUMO gaps) are calculated for the studied adsorbents in order to explain the above-mentioned tendencies. Finally, the effect of the presence of heteroatoms on the enthalpy of reaction (Δ H298) for all CO 2-heteroatom-doping adsorbent complexes is shown. Thus, carbon dioxide molecules adsorb on the edge plane surface of N-, O-, OH-containing carbon surfaces similarly or much less favourably in comparison with the "unmodified" adsorbents. This confirms some experimental observations.

  12. Computer-Based Materials: A Study of Learner Autonomy and Strategies (United States)

    Figura, Klaudia; Jarvis, Huw


    This paper reports on a study which examines the extent to which specified cognitive, social, and metacognitive strategies, are used by language students when working with computer-based materials (CBMs), in self-study contexts outside of the language classroom; particularly in a self-access centre (SAC). Data were collected using questionnaires,…

  13. Micro-Computed Tomography and Finite Element Method Study of Open-Cell Porous Materials

    Directory of Open Access Journals (Sweden)

    Wejrzanowski Tomasz


    Full Text Available In the present paper the characterization of structure and properties of open-cell porous materials by high-resolution x-ray micro-computed tomography (μCT and finite element method (FEM is addressed. The unique properties of open porosity foams make them interesting in a range of applications in science and engineering such as energy absorbers, lightweight construction materials or heat insulators. Consequently, a detailed knowledge of structure as well as mechanical properties (i.e. Young’s Modulus, Poisson’s Ratio of such foams is essential. The resulting pixel size of the μCT was 40 μm, which enabled satisfactory visualization of the complex foam structure and quantitative characterization. Foam morphology was studied on post-processed computed tomography images, while mechanical properties were analyzed with use of the finite element method on numerical model obtained from μCT results.

  14. Computational studies on 1,2,4-Triazolium-based salts as energetic materials

    Indian Academy of Sciences (India)

    Rakhi Singh; Hari Ji Singh; S K Sengupta


    The results of the computational studies performed on 1,2,4-triazolium cation-based salts designed by pairing it with energetic nitro-substituted 5- membered N-heterocyclic anions such as 5-nitrotetrazolate, 3,5-dinitrotriazolate, and 2,4,5 trinitroimidazolate are reported. Condensed phase heats of formation of the designed ionic salts and their thermodynamic and energetic properties have also been calculated. The results show that these salts are potential energetic materials and possess high positive heats of formation. The detonation velocity, D, and detonation pressure, P, have been calculated using the Kamlet-Jacobs equation and found to be 7–8 km/s and 25–29 GPa, respectively. These values fall in the range of the criteria to designate them as high-energy-density materials. Nucleus independent chemical shift (NICS) studies performed on the designed molecules show that these salts are stable in nature.

  15. 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)


    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.

  16. Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study. Phase I (United States)

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


    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

  17. A computational study of influence of helmet padding materials on the human brain under ballistic impacts. (United States)

    Salimi Jazi, Mehdi; Rezaei, Asghar; Karami, Ghodrat; Azarmi, Fardad; Ziejewski, Mariusz


    The results of a computational study of a helmeted human head are presented in this paper. The focus of the work is to study the effects of helmet pad materials on the level of acceleration, inflicted pressure and shear stress in a human brain model subjected to a ballistic impact. Four different closed cell foam materials, made of expanded polystyrene and expanded polypropylene, are examined for the padding material. It is assumed that bullets cannot penetrate the helmet shell. Finite element modelling of the helmet, padding system, head and head components is used for this dynamic nonlinear analysis. Appropriate contacts and conditions are applied between the different components of the head, as well as between the head and the pads, and the pads and the helmet. Based on the results of simulations in this work, it is concluded that the stiffness of the foam has a prominent role in reducing the level of the transferred load to the brain. A pad that is less stiff is more efficient in absorbing the impact energy and reducing the sudden acceleration of the head and consequently lowers the brain injury level. Using the pad with the least stiffness, the influence of the angle of impacts as well as the locations of the ballistic strike is studied.

  18. Effect of Collaborative Studies on Prospective Teachers’ Creative Thinking Skills while Designing Computer Based Material

    Directory of Open Access Journals (Sweden)

    Salih BİRİŞÇİ


    Full Text Available The purpose of this study to examine effect of collaborative studies on prospective teachers‟ creative thinking skills while designing computer based materials. One group pre-test and post-test design of the pre-experimental model was used to achieve the objectives of the study. This experimental study have been applied to 34 prospective teachers who studied at Artvin Coruh University Facult of Education Primary Education Department in 2009-2010 spring term within the context of “Computer-II” course. “Creative Thinking Skill Scale” was applied at two different stages as pre-test and post-test and opinions of students were gathered about the method in research via interview forms. As a result, it was found that there was a significant difference between the prospective teachers‟ creative thinking skills and scores taken from scale were increased in favor of post-test. Collaborative group works have a great importance in occurrence of this increase was revealed from student views.

  19. Computing and Material

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette; Tamke, Martin


    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....

  20. An Experimental and Computational Study of Directional Solidification in Transparent Materials (United States)

    Simpson, James E.; deGroh, Henry C., III; Garimella, Suresh V.


    An experimental and numerical study of the horizontal Bridgman growth of pure succinonitrile (SCN) and of a succinonitrile- 1.0 mol.% acetone alloy (SCN- 1.0 mol.% ACE) has been performed. Experiments at growth rates of 0, 2 and 40 micron/s were investigated. The solid/liquid interface was stable (non-dendritic and non-cellular); however, it was not flat. Rather, it was significantly distorted by the influence of convection in the melt and, for the growth cases, by the moving temperature boundary conditions along the ampoule. For the alloy, the interface was.determined to be unstable at growth rates greater than 2.8 micron/s, but stable for the no-growth and 2 micron/s growth cases. When compared to the pure SCN interface, the alloy interface forms closer to the cold zone, indicating that the melting temperature has been suppressed by the addition of the alloying element. Two-dimensional computer simulations were performed for the no-growth case for both the pure and alloy materials. These simulations indicate that a primary longitudinal convective cell is formed in the melt. The maximum magnitude of velocity was calculated to be 1.515 mm/s for pure SCN and 1.724 mm/s for the alloy. The interface shape predicted by the computer simulation agrees well with the experimentally determined shape for the pure SCN case. In ongoing work, numerical simulations of the process during growth conditions are being performed.

  1. Computational approaches to energy materials

    CERN Document Server

    Catlow, Richard; Walsh, Aron


    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


    Energy Technology Data Exchange (ETDEWEB)



    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.

  3. Computational 2D Materials Database

    DEFF Research Database (Denmark)

    Rasmussen, Filip Anselm; Thygesen, Kristian Sommer


    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....

  4. Computer simulation in materials science

    Energy Technology Data Exchange (ETDEWEB)

    Arsenault, R.J.; Beeler, J.R.; Esterling, D.M.


    This book contains papers on the subject of modeling in materials science. Topics include thermodynamics of metallic solids and fluids, grain-boundary modeling, fracture from an atomistic point of view, and computer simulation of dislocations on an atomistic level.

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

    Directory of Open Access Journals (Sweden)

    Benedito Antonio Luciano


    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.

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

    CERN Document Server

    Stimson, L M


    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 s...

  7. 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)


    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.

  8. Computational and Experimental Study of Energetic Material in a Counterflow Microgravity Environment (United States)

    Smooke, Mitchell D.; Yetter, R. A.; Parr, T. P.; Hanson-Parr, D. M.; Tanoff, M. A.


    Ground based (normal gravity) combustion studies can provide important information on the processes by which monopropellants and composite systems burn. The effects of gravitational forces, however, can often complicate the interpretation of the models and the implementation of experiments designed to help elucidate complex issues. We propose to utilize a combined computational/experimental approach in a microgravity environment to understand the interaction of oxidizer-binder diffusion flames in composite propellants. By operating under microgravity conditions we will be able to increase the length scales and suppress the gravitational forces on melting binders such that increased resolution of both major and minor species will be possible thus reducing the demands placed on both the computational and diagnostic tools. Results of a detailed transport/finite rate chemistry model will be compared with nonintrusive optical diagnostic measurements of the structure and extinction of diffusion flames in which oxidizers such as ammonium perchlorate (AP) and ammonium dinitramide (ADN) are counterflowed against realistic binders such as hydroxyl-terminated polybutadiene (HTPB) and 3,3-bis(azidomethyl)oxetane (BAMO). The work proposed herein represents a collaborative effort among the research groups at Yale University, Princeton University and the Combustion Diagnostics Laboratory at the Naval Air Warfare Center in China Lake, CA.

  9. Computational development of the nanoporous materials genome (United States)

    Boyd, Peter G.; Lee, Yongjin; Smit, Berend


    There is currently a push towards big data and data mining in materials research to accelerate discovery. Zeolites, metal-organic frameworks and other related crystalline porous materials are not immune to this phenomenon, as evidenced by the proliferation of porous structure databases and computational gas-adsorption screening studies over the past decade. The endeavour to identify the best materials for various gas separation and storage applications has led not only to thousands of synthesized structures, but also to the development of algorithms for building hypothetical materials. The materials databases assembled with these algorithms contain a much wider range of complex pore structures than have been synthesized, with the reasoning being that we have discovered only a small fraction of realizable structures and expanding upon these will accelerate rational design. In this Review, we highlight the methods developed to build these databases, and some of the important outcomes from large-scale computational screening studies.

  10. Computational study on the behaviors of granular materials under mechanical cycling (United States)

    Wang, Xiaoliang; Ye, Minyou; Chen, Hongli


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoliang; Ye, Minyou; Chen, Hongli, E-mail: [School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026 (China)


    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.

  12. Computational Material Processing in Microgravity (United States)


    Working with Professor David Matthiesen at Case Western Reserve University (CWRU) a computer model of the DPIMS (Diffusion Processes in Molten Semiconductors) space experiment was developed that is able to predict the thermal field, flow field and concentration profile within a molten germanium capillary under both ground-based and microgravity conditions as illustrated. These models are coupled with a novel nonlinear statistical methodology for estimating the diffusion coefficient from measured concentration values after a given time that yields a more accurate estimate than traditional methods. This code was integrated into a web-based application that has become a standard tool used by engineers in the Materials Science Department at CWRU.

  13. Computation in mechanics of materials (United States)

    Asaro, R. J.; Clifton, R. J.; Freund, L. B.


    The goal of this project, which was part of the DARPA Balanced Technology Initiative on Computational Mechanics, was to develop a comprehensive approach to the numerical modeling of the mechanical behavior of materials. Particular areas for focus in the project were the inelastic deformation of highly anisotropic materials such as single crystals and textured polycrystals, as well as evolving microstructural damage in ceramics and ductile metals in both slow and high rate deformation processes. While the contract was awarded for a period of four years, it was actually funded only for the first year plus a few months into the second year. Nonetheless, significant progress can be reported as a direct result of this project.

  14. An experimental, theoretical and event-driven computational study of narrow vibrofluidised granular materials (United States)

    Thornton, Anthony; Windows-Yule, Kit; Parker, David; Luding, Stefan


    We review simulations, experiments and a theoretical treatment of vertically vibrated granular media. The systems considered are confined in narrow quasi-two-dimensional and quasi-one-dimensional (column) geometries, where the vertical extension of the container is much larger than one or both horizontal lengths. The additional geometric constraint present in the column setup frustrates the convection state that is normally observed in wider geometries. We start by showing that the Event Driven (ED) simulation method is able to accurately reproduce the previously experimentally determined phase-diagram for vibrofludised granular materials. We then review two papers that used ED simulations to study narrow quasi-one-dimensional systems revealing a new phenomenon: collective oscillations of the grains with a characteristic frequency that is much lower than the frequency of energy injection. Theoretical work was then undertaken that is able to accurately predict the frequency of such an oscillation and Positron Emission Particle Tracking (PEPT) experiments were undertaken to provide the first experimental evidence of this new phenomenon. Finally, we briefly discuss ongoing work to create an open-source version of this ED via its integration in the existing open-source package MercuryDPM (; which has many advanced features that are not found in other codes.

  15. Computational studies on energetic properties of nitrogen-rich energetic materials with ditetrazoles

    Indian Academy of Sciences (India)

    Li Xiao-Hong; Zhang Rui-Zhou


    Based on the full optimized molecular geometric structures at B3LYP/6-311++G**level, the densities (), heats of formation (HOFs), detonation velocities (D) and pressures (P) for a series of ditetrazoles derivatives, were investigated to look for high energy density materials (HEDMs). The results show that the influence of different substituted groups on HOFs has the order of -N3>-CN>-NH2>-NO2>-NF2>-ONO2>-H>-CH3>-CF3. The introduction of -CF3 groups is more favourable for increasing the density and the introduction of -CH3 groups is not favourable for increasing the density. In addition, all the series combined with -NF2 group except B-NF2 all have higher densities, larger D and P. F-NF2 may be regarded as the potential candidates of HEDMs because of the largest detonation velocity and pressure among these derivatives.The energy gaps between the HOMO and LUMO of the studied compounds are also investigated.

  16. Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study Project (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...

  17. Requirements for accurate estimation of anisotropic material parameters by magnetic resonance elastography: A computational study. (United States)

    Tweten, D J; Okamoto, R J; Bayly, P V


    To establish the essential requirements for characterization of a transversely isotropic material by magnetic resonance elastography (MRE). Three methods for characterizing nearly incompressible, transversely isotropic (ITI) materials were used to analyze data from closed-form expressions for traveling waves, finite-element (FE) simulations of waves in homogeneous ITI material, and FE simulations of waves in heterogeneous material. Key properties are the complex shear modulus μ2 , shear anisotropy ϕ=μ1/μ2-1, and tensile anisotropy ζ=E1/E2-1. Each method provided good estimates of ITI parameters when both slow and fast shear waves with multiple propagation directions were present. No method gave accurate estimates when the displacement field contained only slow shear waves, only fast shear waves, or waves with only a single propagation direction. Methods based on directional filtering are robust to noise and include explicit checks of propagation and polarization. Curl-based methods led to more accurate estimates in low noise conditions. Parameter estimation in heterogeneous materials is challenging for all methods. Multiple shear waves, both slow and fast, with different propagation directions, must be present in the displacement field for accurate parameter estimates in ITI materials. Experimental design and data analysis can ensure that these requirements are met. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  18. Computer-Supported Resolution of Measurement Conflicts: A Case-Study in Materials Science

    NARCIS (Netherlands)

    Jong, de Hidde; Mars, Nicolaas; Vet, van der Paul


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

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


    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.

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

    KAUST Repository

    Forrest, Katherine A.


    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

  1. Removal of filling materials from oval-shaped canals using laser irradiation: a micro-computed tomographic study. (United States)

    Keleş, Ali; Arslan, Hakan; Kamalak, Aliye; Akçay, Merve; Sousa-Neto, Manoel D; Versiani, Marco Aurélio


    The aim of this study was to assess the efficacy of lasers in removing filling remnants from oval-shaped canals after retreatment procedures with rotary instruments using micro-computed tomographic imaging. The root canals of 42 mandibular canines were prepared and obturated using the warm vertical compaction technique. Retreatment was performed with rotary instruments, and the specimens were distributed in 3 groups (n = 14) according to the laser device used in a later stage of retreatment procedure: Er:YAG, Er:YAG laser-based photon-induced photoacoustic streaming, and Nd:YAG. The specimens were scanned in a micro-computed tomographic device after root canal filling and each stage of retreatment at a resolution of 13.68 μm. The percentage differences of the remaining filling material before and after laser application within and between groups were statistically compared using the paired sample t test and 1-way analysis of variance test, respectively. Significance level was set at 5%. Overall, filling residues were located mainly in the apical third and into canal irregularities after the retreatment procedures. After using rotary instruments, the mean percentage volume of the filling remnants ranged from 13%-16%, with no statistical significant difference between groups (P > .05). Within groups, additional laser application had a significant reduction in the amount of the remaining filling materials (P materials. The additional use of lasers improved the removal of filling material after the retreatment procedure with rotary instruments. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  2. 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)


    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

  3. Computational Models of Material Interfaces for the Study of Extracorporeal Shock Wave Therapy

    CERN Document Server

    Fagnan, Kirsten; Matula, Thomas J


    Extracorporeal Shock Wave Therapy (ESWT) is a noninvasive treatment for a variety of musculoskeletal ailments. A shock wave is generated in water and then focused using an acoustic lens or reflector so the energy of the wave is concentrated in a small treatment region where mechanical stimulation enhances healing. In this work we have computationally investigated shock wave propagation in ESWT by solving a Lagrangian form of the isentropic Euler equations in the fluid and linear elasticity in the bone using high-resolution finite volume methods. We solve a full three-dimensional system of equations and use adaptive mesh refinement to concentrate grid cells near the propagating shock. We can model complex bone geometries, the reflection and mode conversion at interfaces, and the the propagation of the resulting shear stresses generated within the bone. We discuss the validity of our simplified model and present results validating this approach.

  4. Experimental and Computer Simulation Study of Radioactivity of Materials Irradiated by Intermediate Energy Protons

    CERN Document Server

    Titarenko, Y E; Batyaev, V F; Karpikhin, E I; Zhivun, V M; Mulambetov, R D; Mashnik, S G; Prael, R E; Wilson, W B; Titarenko, Yu. E.


    The results of measurements and computer simulations of radioactivities and dose rates as functions of decay time are presented for Pb-nat and Bi-209 irradiated by 1.5-GeV protons, Co-59, Cu-63, and Cu-65 irradiated by 0.13- and 1.2-GeV protons, and Th-232 and U-nat irradiated by 0.1- and 0.8-GeV protons. The activities and dose rates are measured by direct high-precision gamma spectrometry. The irradiations were made using external beams extracted from the ITEP U-10 proton synchrotron. Simulations made using the LCS and CINDER'90 code systems are compared with measurements.

  5. Computational matter: evolving computational solutions in materials

    NARCIS (Netherlands)

    Miller, Julian F.; Broersma, Hajo; Silva, Sara


    Natural Evolution has been exploiting the physical properties of matter since life first appeared on earth. Evolution-in-materio (EIM) attempts to program matter so that computational problems can be solved. The beauty of this approach is that artificial evolution may be able to utilize unknown phys

  6. Computer simulations applied in materials

    Energy Technology Data Exchange (ETDEWEB)



    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.)

  7. Computer simulations applied in materials

    Energy Technology Data Exchange (ETDEWEB)



    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.)

  8. Pattern recognition with "materials that compute". (United States)

    Fang, Yan; Yashin, Victor V; Levitan, Steven P; Balazs, Anna C


    Driven by advances in materials and computer science, researchers are attempting to design systems where the computer and material are one and the same entity. Using theoretical and computational modeling, we design a hybrid material system that can autonomously transduce chemical, mechanical, and electrical energy to perform a computational task in a self-organized manner, without the need for external electrical power sources. Each unit in this system integrates a self-oscillating gel, which undergoes the Belousov-Zhabotinsky (BZ) reaction, with an overlaying piezoelectric (PZ) cantilever. The chemomechanical oscillations of the BZ gels deflect the PZ layer, which consequently generates a voltage across the material. When these BZ-PZ units are connected in series by electrical wires, the oscillations of these units become synchronized across the network, where the mode of synchronization depends on the polarity of the PZ. We show that the network of coupled, synchronizing BZ-PZ oscillators can perform pattern recognition. The "stored" patterns are set of polarities of the individual BZ-PZ units, and the "input" patterns are coded through the initial phase of the oscillations imposed on these units. The results of the modeling show that the input pattern closest to the stored pattern exhibits the fastest convergence time to stable synchronization behavior. In this way, networks of coupled BZ-PZ oscillators achieve pattern recognition. Further, we show that the convergence time to stable synchronization provides a robust measure of the degree of match between the input and stored patterns. Through these studies, we establish experimentally realizable design rules for creating "materials that compute."

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

    Directory of Open Access Journals (Sweden)

    Vikas D. Ghule


    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.


    Directory of Open Access Journals (Sweden)

    Amare Matebu


    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.

  11. Computer aided materials design; Keisanki zairyo sekkei

    Energy Technology Data Exchange (ETDEWEB)



    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.

  12. 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)


    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.

  13. Computational Amphiphilic Materials for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Naresh eThota


    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.

  14. Computed tomography characterisation of additive manufacturing materials. (United States)

    Bibb, Richard; Thompson, Darren; Winder, John


    Additive manufacturing, covering processes frequently referred to as rapid prototyping and rapid manufacturing, provides new opportunities in the manufacture of highly complex and custom-fitting medical devices and products. Whilst many medical applications of AM have been explored and physical properties of the resulting parts have been studied, the characterisation of AM materials in computed tomography has not been explored. The aim of this study was to determine the CT number of commonly used AM materials. There are many potential applications of the information resulting from this study in the design and manufacture of wearable medical devices, implants, prostheses and medical imaging test phantoms. A selection of 19 AM material samples were CT scanned and the resultant images analysed to ascertain the materials' CT number and appearance in the images. It was found that some AM materials have CT numbers very similar to human tissues, FDM, SLA and SLS produce samples that appear uniform on CT images and that 3D printed materials show a variation in internal structure.

  15. Economics of End-of-Life Materials Recovery: A Study of Small Appliances and Computer Devices in Portugal. (United States)

    Ford, Patrick; Santos, Eduardo; Ferrão, Paulo; Margarido, Fernanda; Van Vliet, Krystyn J; Olivetti, Elsa


    The challenges brought on by the increasing complexity of electronic products, and the criticality of the materials these devices contain, present an opportunity for maximizing the economic and societal benefits derived from recovery and recycling. Small appliances and computer devices (SACD), including mobile phones, contain significant amounts of precious metals including gold and platinum, the present value of which should serve as a key economic driver for many recycling decisions. However, a detailed analysis is required to estimate the economic value that is unrealized by incomplete recovery of these and other materials, and to ascertain how such value could be reinvested to improve recovery processes. We present a dynamic product flow analysis for SACD throughout Portugal, a European Union member, including annual data detailing product sales and industrial-scale preprocessing data for recovery of specific materials from devices. We employ preprocessing facility and metals pricing data to identify losses, and develop an economic framework around the value of recycling including uncertainty. We show that significant economic losses occur during preprocessing (over $70 M USD unrecovered in computers and mobile phones, 2006-2014) due to operations that fail to target high value materials, and characterize preprocessing operations according to material recovery and total costs.

  16. Computational Screening of Energy Materials

    DEFF Research Database (Denmark)

    Pandey, Mohnish

    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......, a single material cannot accomplish the whole process of the hydrogen evolution. In order do so, a material should be able to absorb the sunlight and generate the electronhole pairs and evolve hydrogen at the cathode and oxygen at anode using the generated electron and hole respectively. This thesis using...... first-principle calculations explores materials for the light absorption with the bandgap, band edge positions and the stability in aqueous conditions as descriptors. This strategy results in a handful of materials which can act as good photoabsorbers for the water splitting reaction. Additionally...

  17. Design and computation of modern engineering materials

    CERN Document Server

    Altenbach, Holm


     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.

  18. Computational materials science: Nanoscale plasticity

    DEFF Research Database (Denmark)

    Jacobsen, Karsten Wedel; Schiøtz, Jakob


    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....

  19. Micro-Computed Tomography Study of Filling Material Removal from Oval-shaped Canals by Using Rotary, Reciprocating, and Adaptive Motion Systems. (United States)

    Crozeta, Bruno Monguilhott; Silva-Sousa, Yara Teresinha Correa; Leoni, Graziela Bianchi; Mazzi-Chaves, Jardel Francisco; Fantinato, Thais; Baratto-Filho, Flares; Sousa-Neto, Manoel Damião


    This study evaluated filling material removal from distal oval-shaped canals of mandibular molars with rotary, reciprocating, and adaptive motion systems by using micro-computed tomography. After cone-beam computed tomography scanning, 21 teeth were selected, prepared up to a size 40 file, root filled, and divided into 3 groups (n = 7) according to the filling material removal technique: group PTUR, ProTaper Universal Retreatment combined with ProTaper Universal F2, F3, F4, and F5 files; group RP, Reciproc R50 file; and group TFA: TF Adaptive 50.04 files. The specimens were scanned preoperatively and postoperatively to assess filling material removal by using micro-computed tomography imaging, and the percent volume of residual filling material was calculated. The statistical analysis showed the lowest percent volume of residual filling material at the coronal third in all groups (P  .05). In the middle third, group TFA (31.2 ± 10.1) showed lower volume of residual filling material than group RP (52.4 ± 14.1) (P material than group RP (70.6 ± 7.2) (P material from the canals. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  20. Computational Nanotechnology Molecular Electronics, Materials and Machines (United States)

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


    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.

  1. Computation of single solid particle impact on the target of ductile material to study the rebound characteristics of particle (United States)

    Yeuan, Jian Jong


    The objective of this research work is to simulate a single solid particle impact on a solid target using elastic-plastic theory. The entire impact process involves the adhesion, deformation and rebound process interacting between the solid particle and the target. The governing equations for two dimensional elastic-plastic flow are formulated in Lagrangian coordinates. The equation of state in the elastic region is the time rate of change of Hooke's law. In the plastic region, the experimental Hugoniot equation of state and the yield condition of R. von Mises are used. The effect of strain rate on the material strength is considered using a semi-empirical formulation. The developed computer program employs a finite volume numerical technique and two step explicit MacCormack scheme, which is second order accurate in time, allowing finer resolution of the transient phenomena of impact. Results are presented for a hard tool steel particle impacting on a mild steel target at impact angles of 20 to 90 degrees. The computational results are compared with experimental data for a range of impacting velocities up to 350 m/sec. The effect of particle in the particle rebound characteristics are also investigated. In the previous research, the particle rebound characteristics obtained from experiments were correlated and used in the calculation of particle trajectories in turbomachinery flows. Here, the computational results are applied to predict solid particle trajectories in a highly loaded axial flow turbine.

  2. Computationally Guided Discovery of Thermoelectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    Gorai, Prashun [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stevanovic, Vladan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Toberer, Eric [National Renewable Energy Laboratory (NREL), Golden, CO (United States)


    The potential for advances in thermoelectric materials, and thus solid-state refrigeration and power generation, is immense. Progress so far has been limited by both the breadth and diversity of the chemical space and the serial nature of experimental work. In this Review, we discuss how recent computational advances are revolutionizing our ability to predict electron and phonon transport and scattering, as well as materials dopability, and we examine efficient approaches to calculating critical transport properties across large chemical spaces. When coupled with experimental feedback, these high-throughput approaches can stimulate the discovery of new classes of thermoelectric materials. Within smaller materials subsets, computations can guide the optimal chemical and structural tailoring to enhance materials performance and provide insight into the underlying transport physics. Beyond perfect materials, computations can be used for the rational design of structural and chemical modifications (such as defects, interfaces, dopants and alloys) to provide additional control on transport properties to optimize performance. Through computational predictions for both materials searches and design, a new paradigm in thermoelectric materials discovery is emerging.

  3. Materials science. Materials that couple sensing, actuation, computation, and communication. (United States)

    McEvoy, M A; Correll, N


    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.

  4. Non-equilibrium grain boundaries in titanium nanostructured by severe plastic deformation: Computational study of sources of material strengthening

    DEFF Research Database (Denmark)

    Liu, Hongsheng; Mishnaevsky, Leon; Pantleon, Wolfgang


    A computational model of ultrafine grained (UFG) or nanostructured titanium (Ti), based on a finite element (FE) unit cell model of the material and a dislocation density based model of plastic deformation has been developed. FE simulations of tensile deformation of UFG Ti with different fractions...... and properties of the grain boundary (GB) phase have been carried out. The effect of different degrees of deviation from the equilibrium state of the grain boundaries (GBs) on the mechanical behaviour of nanostructured Ti have been investigated using the combined composite/dislocation dynamics based model....... In particular, the effects of different diffusion coefficients in the GB phase, of a high initial dislocation density in the grain boundaries, as well as of atomic scale precipitates are investigated for affecting the deformation behaviour of UFG or nanostructured Ti. © 2013 Elsevier B.V. All rights reserved....

  5. Computational modelling in materials at the University of the North

    CSIR Research Space (South Africa)

    Ngoepe, PE


    Full Text Available The authors review computational modelling studies in materials resulting from the National Research Foundation-Royal Society collaboration. Initially, investigations were confined to transport and defect properties in fluorine and oxygen ion...

  6. Computational prediction of new auxetic materials. (United States)

    Dagdelen, John; Montoya, Joseph; de Jong, Maarten; Persson, Kristin


    Auxetics comprise a rare family of materials that manifest negative Poisson's ratio, which causes an expansion instead of contraction under tension. Most known homogeneously auxetic materials are porous foams or artificial macrostructures and there are few examples of inorganic materials that exhibit this behavior as polycrystalline solids. It is now possible to accelerate the discovery of materials with target properties, such as auxetics, using high-throughput computations, open databases, and efficient search algorithms. Candidates exhibiting features correlating with auxetic behavior were chosen from the set of more than 67 000 materials in the Materials Project database. Poisson's ratios were derived from the calculated elastic tensor of each material in this reduced set of compounds. We report that this strategy results in the prediction of three previously unidentified homogeneously auxetic materials as well as a number of compounds with a near-zero homogeneous Poisson's ratio, which are here denoted "anepirretic materials".There are very few inorganic materials with auxetic homogenous Poisson's ratio in polycrystalline form. Here authors develop an approach to screening materials databases for target properties such as negative Poisson's ratio by using stability and structural motifs to predict new instances of homogenous auxetic behavior as well as a number of materials with near-zero Poisson's ratio.

  7. Material stiffness parameters as potential predictors of presence of left ventricle myocardial infarction: 3D echo-based computational modeling study. (United States)

    Fan, Longling; Yao, Jing; Yang, Chun; Wu, Zheyang; Xu, Di; Tang, Dalin


    Ventricle material properties are difficult to obtain under in vivo conditions and are not readily available in the current literature. It is also desirable to have an initial determination if a patient had an infarction based on echo data before more expensive examinations are recommended. A noninvasive echo-based modeling approach and a predictive method were introduced to determine left ventricle material parameters and differentiate patients with recent myocardial infarction (MI) from those without. Echo data were obtained from 10 patients, 5 with MI (Infarct Group) and 5 without (Non-Infarcted Group). Echo-based patient-specific computational left ventricle (LV) models were constructed to quantify LV material properties. All patients were treated equally in the modeling process without using MI information. Systolic and diastolic material parameter values in the Mooney-Rivlin models were adjusted to match echo volume data. The equivalent Young's modulus (YM) values were obtained for each material stress-strain curve by linear fitting for easy comparison. Predictive logistic regression analysis was used to identify the best parameters for infract prediction. The LV end-systole material stiffness (ES-YMf) was the best single predictor among the 12 individual parameters with an area under the receiver operating characteristic (ROC) curve of 0.9841. LV wall thickness (WT), material stiffness in fiber direction at end-systole (ES-YMf) and material stiffness variation (∆YMf) had positive correlations with LV ejection fraction with correlation coefficients r = 0.8125, 0.9495 and 0.9619, respectively. The best combination of parameters WT + ∆YMf was the best over-all predictor with an area under the ROC curve of 0.9951. Computational modeling and material stiffness parameters may be used as a potential tool to suggest if a patient had infarction based on echo data. Large-scale clinical studies are needed to validate these preliminary findings.

  8. Evaluation of the Efficacy of TRUShape and Reciproc File Systems in the Removal of Root Filling Material: An Ex Vivo Micro-Computed Tomographic Study. (United States)

    de Siqueira Zuolo, Arthur; Zuolo, Mario Luis; da Silveira Bueno, Carlos Eduardo; Chu, Rene; Cunha, Rodrigo Sanches


    The purpose of this study was to evaluate the efficacy of TRUShape (Dentsply Tulsa Dental Specialties, Tulsa, OK) compared with the Reciproc file (VDW, Munich, Germany) in the removal of filling material from oval canals filled with 2 different sealers and differences in the working time. Sixty-four mandibular canines with oval canals were prepared and divided into 4 groups (n = 16). Half of the specimens were filled with gutta-percha and pulp canal sealer (PCS), and the remainders were filled with gutta-percha and bioceramic sealer (BCS). The specimens were retreated using either the Reciproc or TRUShape files. A micro-computed tomographic scanner was used to assess filling material removal, and the time taken for removal was also recorded. Data were analyzed using the Kruskal-Wallis and Mann-Whitney U tests. The mean volume of the remaining filling material was similar when comparing both files (P ≥ .05). However, in the groups filled with BCS, the percentage of remaining filling material was higher than in the groups filled with PCS (P material when comparing both files system; however, Reciproc was faster than TRUShape. BCS groups exhibited significantly more remaining filling material in the canals and required more time for retreatment. Remaining filling material was observed in all samples regardless of the technique or sealer used. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  9. Water in Metal-Organic Frameworks: A Computational Study of Adsorption in Porous Materials in the Presence of Ambient Humidity (United States)

    Ghosh, Pritha

    Metal-organic frameworks, or MOFs, are a class of porous crystalline materials renowned for their chemically tunable nature. In this work, molecular-level modeling is used to assess MOFs as potential adsorbents for a variety of applications where ambient humidity is present, such as toxic gas capture, nerve agent decomposition, and sensing via changes in proton conductivity. The concept of hydrophobicity in MOFs is explored from a number of angles. Classical simulation methods and quantum chemistry calculations are used to predict adsorption behavior and to shed light on experimentally observed phenomena. Hydrophobic MOFs are attractive candidates for selective gas capture under ambient conditions, and in this work hydrophobic MOFs are examined for two particular applications: ammonia capture and CO2 capture. In the first study, GCMC simulations are used to evaluate a set of three hydrophobic MOFs for ammonia capture at three humidity conditions: 0% relative humdity (RH), 36% RH, and 80% RH. In the second study, GCMC simulations predict the CO2 loading in a hydrophobic fluorinated MOF at 80% RH, which is the humidity of flue gas. In both of these studies, results demonstrate that hydrophobic MOFs are equally capable of capturing the target adsorbate under humid or dry conditions. In related work, water adsorption behavior is investigated for a fairly hydrophilic Zr MOF, and it is revealed that missing linker defects engender hydrophilicity in this framework. An ideal, defect-free version of this Zr MOF demonstrates hydrophobic behavior. Additionally, perfluoroalkane adsorption is predicted in a related material, a faujasite-type zeolite, and the results suggest the presence of co-adsorbed water molecules. MOFs with coordinated solvent molecules can be used as catalysts and novel chemical sensors. In this work, quantum chemistry calculations are used to study the interaction of a nerve agent simulant with a Zr MOF node. Results indicate that it is favorable for a

  10. Computational Materials: Modeling and Simulation of Nanostructured Materials and Systems (United States)

    Gates, Thomas S.; Hinkley, Jeffrey A.


    The paper provides details on the structure and implementation of the Computational Materials program at the NASA Langley Research Center. Examples are given that illustrate the suggested approaches to predicting the behavior and influencing the design of nanostructured materials such as high-performance polymers, composites, and nanotube-reinforced polymers. Primary simulation and measurement methods applicable to multi-scale modeling are outlined. Key challenges including verification and validation of models are highlighted and discussed within the context of NASA's broad mission objectives.

  11. Optimizing a reconfigurable material via evolutionary computation (United States)

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


    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.

  12. Influence of muscle activation and mucosal material property on esophageal transport: study based on a fully-resolved computational model (United States)

    Kou, Wenjun; Pandolfino, John; Kahrilas, Peter; Patankar, Neelesh


    Esophageal transport involves interactions between food (bolus), the esophageal walls (composed of mucosal, circular muscle (CM) and longitudinal muscle (LM) layers), and neurally coordinated muscle activation including CM contraction and LM shortening. Due to the complexity of these interactions, few studies have been conducted on the mechanical role of the mucosal layer in esophageal transport. Also poorly understood are the collaborative roles of CM contraction and LM shortening and the influence of their synchronization. Here, based on a fully-resolved computational model that we developed, we investigated the individual roles of CM contraction and LM shortening, compared bolus transport with various levels of discoordination between CM and LM activation, and studied the role of the mucosa and how its stiffening influenced transport. These preliminary findings should help understand the synergy between LM, CM, and the mucosal layer in facilitating bolus transport, thereby providing insight into related physiology and pathophysiology. The support of Grant R01 DK56033 and R01 DK079902 from NIH is gratefully acknowledged.

  13. Synthesis, an experimental and quantum chemical computational study of a new nonlinear optical material: 2-picolinium hydrogensquarate. (United States)

    Korkmaz, Ufuk; Bulut, Ahmet


    The experimental and theoretical investigation results of a novel organic non-linear optical (NLO) organic squarate salt of 2-Picolinium hydrogensquarate (1), C6H8N+·C4HO4-, were reported in this study. The space group of the title compound was found in the monoclinic C2/c space group. It was found that the asymmetric unit consists of one monohydrogen squarate anion together with mono protonated 2-Picolinium, forming the (1) salt. The X-ray analysis clearly indicated that the crystal packing has shown the hydrogen bonding ring pattern of D2(2)(10) (α-dimer) through NH⋯O interactions. The hydrogensquarate anions form α-dimer, while 2-Picolinium molecule interacts through NH⋯O and CH⋯O with the hydrogensquarate anion. The structural and vibrational properties of the compound were also studied by computational methods of ab initio performed on the compound at DFT/B3LYP/6-31++G(d,p) (2) and HF/6-31++G(d,p) (3) level of theory. The calculation results on the basis of two models for both the optimized molecular structure and vibrational properties for the 1 obtained are presented and compared with the X-ray analysis result. On the other the molecular electrostatic potential (MEP), electronic absorption spectra, frontier molecular orbitals (FMOs), conformational flexibility and non-linear optical properties (NLO) of the title compound were also studied at the 2 level and the results are reported. In order to evaluate the suitability for NLO applications thermal analysis (TG, DTA and DTG) data of 1 were also obtained.

  14. Opportunities in theoretical and computational polymeric materials and soft matter. (United States)

    Liu, Andrea J; Grest, Gary S; Marchetti, M Cristina; Grason, Gregory M; Robbins, Mark O; Fredrickson, Glenn H; Rubinstein, Michael; Olvera de la Cruz, Monica


    Soft materials are abundant in nature and ubiquitous in living systems. Elucidating their multi-faceted properties and underlying mechanisms is not only theoretically challenging and important in its own right, but also serves as the foundation for new materials and applications that will have wide-ranging impact on technology and the national economy. Recent initiatives in computation and data-driven materials discovery, such as the Materials Genome Initiative and the National Science Foundation Designing Materials to Revolutionize and Engineer our Future (NSF-DMREF) program, recognize and highlight the many future opportunities in the field. Building upon similar past efforts, a workshop was held at the University of California, Santa Barbara in October 2013 to specifically identify the central challenges and opportunities in theoretical and computational studies of polymeric as well as non-polymeric soft materials. This article presents a summary of the main findings of the workshop.

  15. ICAN Computer Code Adapted for Building Materials (United States)

    Murthy, Pappu L. N.


    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.

  16. Effect of Material Ion Exchanges on the Mechanical Stiffness Properties and Shear Deformation of Hydrated Cement Material Chemistry Structure C-S-H Jennit - A Computational Modeling Study (United States)


    performance. Journal of Advanced Concrete Technology , 2003. 1(2): p. 91-126. 11. Martín-Sedeño, M.C., et al., Aluminum-rich belite sulfoaluminate cements...85 33. Bussi , G. and M. Parrinello, Stochastic thermostats: comparison of local and global schemes. Computer Physics Communications, 2008. 179

  17. Effectiveness of the ProTaper Next and Reciproc Systems in Removing Root Canal Filling Material with Sonic or Ultrasonic Irrigation: A Micro-computed Tomographic Study. (United States)

    Martins, Milena Perraro; Duarte, Marco Antonio Hungaro; Cavenago, Bruno Cavalini; Kato, Augusto Shoji; da Silveira Bueno, Carlos Eduardo


    The aim of this study was to evaluate the effectiveness of ProTaper Next (Dentsply Maillefer, Ballaigues, Switzerland) and Reciproc (VDW, Munich, Germany) systems in removing filling material from oval root canals using sonic or ultrasonic irrigation as additional cleaning methods. Thirty-two human extracted mandibular premolars with oval canals were prepared using the ProTaper Universal system (Dentsply Maillefer) up to instrument F4 (40/.06) and then filled by the single-cone technique using Endofill sealer (Dentsply Maillefer). The teeth were randomly divided into 4 groups (n = 8) according to the instrumentation system and the additional cleaning method as follows: Reciproc 40 with ultrasonic activation, Reciproc 40 with sonic agitation, ProTaper Next (X2, X3, and X4) with ultrasonic activation, and ProTaper Next (X2, X3, and X4) with sonic agitation. All specimens were analyzed using micro-computed tomographic imaging before and after removal of the filling material and also after applying the additional cleaning methods. The data, in mm(3) of remaining filling material, were analyzed by the Kruskal-Wallis, Dunn, and Mann-Whitney tests. None of the retreatment protocols completely removed the filling material from the root canals, and there was no significant difference between the instrumentation systems or between root thirds assessed in terms of the average volume of remaining filling material (P > .05). Likewise, no significant difference was observed between the additional cleaning methods in any of the root canal thirds assessed (P > .05). The ProTaper Next and Reciproc systems were equivalent with respect to effectiveness in removing filling material regardless of the additional cleaning method used. The additional cleaning methods were also equivalent and did not improve the removal of filling material significantly. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  18. Computational materials science: The emergence of predictive capabilities of material behaviour

    Indian Academy of Sciences (India)

    Vijay Kumar


    The availability of high performance computers and development of efficient algorithms has led to the emergence of computational materials science as the third branch of materials research complementing the traditional theoretical and experimental approaches. It has created new virtual realities in materials design that are either experimentally not realizable easily or are prohibitively expensive. The possibilities of doing calculations from first principles have led to predictive capabilities that open up new avenues of discovering novel materials with desired properties, understanding material behaviour on the nano- to the macroscopic scale and helping research in new frontiers that could interface between nano-materials and drug design, as well as in understanding biological systems. Here, we describe some significant recent developments related to alloy and steel design as well as the study of matter on the nano-scale — an area that has gained much prominence in current materials research.

  19. A Computational Study on the Use of an Aluminium Metal Matrix Composite and Aramid as Alternative Brake Disc and Brake Pad Material

    Directory of Open Access Journals (Sweden)

    Nosa Idusuyi


    Full Text Available A computational model for the heat generation and dissipation in a disk brake during braking and the following release period has been formulated. The model simulates the braking action by investigating the thermal behaviour occurring on the disc and pad surfaces during this period. A comparative study was made between grey cast iron (GCI, asbestos, Aluminium metal matrix composite (AMC, and aramid as brake pad and disc materials. The braking process and following release period were simulated for four material combinations, GCI disc and Asbestos pad, GCI disc and Aramid pad, AMC disc and Asbestos pad, AMC disc and Aramid pad using COMSOL Multiphysics software. The results show similarity in thermal behaviour at the contact surface for the asbestos and aramid brake pad materials with a temperature difference of 1.8 K after 10 seconds. For the brake disc materials, the thermal behaviour was close, with the highest temperature difference being 9.6 K. The GCI had a peak temperature of 489 K at 1.2 seconds and AMC was 465.5 K but cooling to 406.4 K at 10 seconds, while the GCI was 394.7 K.

  20. Designing with an underdeveloped computational composite for materials experience

    NARCIS (Netherlands)

    Barati, B.; Karana, E.; Hekkert, P.P.M.; Jönsthövel, I.


    In response to the urge for multidisciplinary development of computational composites, designers and material scientists are increasingly involved in collaborative projects to valorize these technology-push materials in the early stages of their development. To further develop the computational

  1. Continuum mechanical and computational aspects of material behavior

    Energy Technology Data Exchange (ETDEWEB)

    Fried, Eliot; Gurtin, Morton E.


    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.

  2. 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


    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)

  3. Petascale lattice-Boltzmann studies of amphiphilic cubic liquid crystalline materials in a globally distributed high-performance computing and visualization environment. (United States)

    Saksena, Radhika S; Mazzeo, Marco D; Zasada, Stefan J; Coveney, Peter V


    We present very large-scale rheological studies of self-assembled cubic gyroid liquid crystalline phases in ternary mixtures of oil, water and amphiphilic species performed on petascale supercomputers using the lattice-Boltzmann method. These nanomaterials have found diverse applications in materials science and biotechnology, for example, in photovoltaic devices and protein crystallization. They are increasingly gaining importance as delivery vehicles for active agents in pharmaceuticals, personal care products and food technology. In many of these applications, the self-assembled structures are subject to flows of varying strengths and we endeavour to understand their rheological response with the objective of eventually predicting it under given flow conditions. Computationally, our lattice-Boltzmann simulations of ternary fluids are inherently memory- and data-intensive. Furthermore, our interest in dynamical processes necessitates remote visualization and analysis as well as the associated transfer and storage of terabytes of time-dependent data. These simulations are distributed on a high-performance grid infrastructure using the application hosting environment; we employ a novel parallel in situ visualization approach which is particularly suited for such computations on petascale resources. We present computational and I/O performance benchmarks of our application on three different petascale systems.

  4. Study of Quantum Computing

    Directory of Open Access Journals (Sweden)

    Prashant Anil Patil


    Full Text Available This paper gives the detailed information about Quantum computer, and difference between quantum computer and traditional computers, the basis of Quantum computers which are slightly similar but still different from traditional computer. Many research groups are working towards the highly technological goal of building a quantum computer, which would dramatically improve computational power for particular tasks. Quantum computer is very much use full for computation purpose in field of Science and Research. Large amount of data and information will be computed, processing, storing, retrieving, transmitting and displaying information in less time with that much of accuracy which is not provided by traditional computers.

  5. Computational materials design for energy applications (United States)

    Ozolins, Vidvuds


    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. Computational methods to determine the structure of hydrogen storage materials (United States)

    Mueller, Tim


    To understand the mechanisms and thermodynamics of material-based hydrogen storage, it is important to know the structure of the material and the positions of the hydrogen atoms within the material. Because hydrogen can be difficult to resolve experimentally computational research has proven to be a valuable tool to address these problems. We discuss different computational methods for identifying the structure of hydrogen materials and the positions of hydrogen atoms, and we illustrate the methods with specific examples. Through the use of ab-initio molecular dynamics, we identify molecular hydrogen binding sites in the metal-organic framework commonly known as MOF-5 [1]. We present a method to identify the positions of atomic hydrogen in imide structures using a novel type of effective Hamiltonian. We apply this new method to lithium imide (Li2NH), a potentially important hydrogen storage material, and demonstrate that it predicts a new ground state structure [2]. We also present the results of a recent computational study of the room-temperature structure of lithium imide in which we suggest a new structure that reconciles the differences between previous experimental and theoretical studies. [4pt] [1] T. Mueller and G. Ceder, Journal of Physical Chemistry B 109, 17974 (2005). [0pt] [2] T. Mueller and G. Ceder, Physical Review B 74 (2006).

  7. Li14P2O3N6 and Li7PN4: Computational study of two nitrogen rich crystalline LiPON electrolyte materials (United States)

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


    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.

  8. FOREWORD: Computational methodologies for designing materials Computational methodologies for designing materials (United States)

    Rahman, Talat S.


    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

  9. A process of material development towards teaching the subject of parabola using computer algebra systems (United States)

    Ardıç, Mehmet Alper; Işleyen, Tevfik


    This study discusses a process of material development towards teaching the subject of the graphs of quadratic functions (parabola) by utilizing computer algebra systems. Additionally, the results obtained during and after the process of developing materials are summarized. The last section of the study provides recommendations for teachers and researchers who want to develop computer-assisted instruction materials.

  10. Multi-material linearization beam hardening correction for computed tomography. (United States)

    Lifton, J J


    Since beam hardening causes cupping and streaking artifacts in computed tomographic images, the presence of such artifacts can impair both qualitative and quantitative analysis of the reconstructed data. When the scanned object is composed of a single material, it is possible to correct beam hardening artifacts using the linearization method. However, for multi-material objects, an iterative segmentation-based correction algorithm is needed, which is not only computationally expensive, but may also fail if the initial segmentation result is poor. In this study, a new multi-material linearization beam hardening correction method was proposed and evaluated. The new method is fast and implemented in the same manner as a mono-material linearization. The correction takes approximately 0.02 seconds per projection. Although facing a potential disadvantage of requiring attenuation measurements of one of the object's constituent materials, applying the new method has demonstrated its capability for a multi-material workpiece with substantial reduction in both cupping and streaking artifacts. For example, the study showed that the absolute cupping artefacts in steel, titanium and aluminum spheres were reduced from 22%, 20% and 20% to 5%, 1% and 0%, respectively.

  11. Study on Parallel Computing

    Institute of Scientific and Technical Information of China (English)

    Guo-Liang Chen; Guang-Zhong Sun; Yun-Quan Zhang; Ze-Yao Mo


    In this paper, we present a general survey on parallel computing. The main contents include parallel computer system which is the hardware platform of parallel computing, parallel algorithm which is the theoretical base of parallel computing, parallel programming which is the software support of parallel computing. After that, we also introduce some parallel applications and enabling technologies. We argue that parallel computing research should form an integrated methodology of "architecture - algorithm - programming - application". Only in this way, parallel computing research becomes continuous development and more realistic.

  12. A computational study on novel carbon-based lithium materials for hydrogen storage and the role of carbon in destabilizing complex metal hydrides (United States)

    Ghouri, Mohammed Minhaj

    One of the major impediments in the way of the realization of hydrogen economy is the storage of hydrogen gas. This involves both the storage for stationary applications as well as that of storage onboard vehicles for transportation applications. For obvious reasons, the system targets for the automotive applications are more stringent. There are many approaches which are still being researched for the storage of hydrogen for vehicular applications. Among them are the high pressure storage of hydrogen gas and the storing of liquid hydrogen in super insulated cryogenic cylinders. While both of them have been demonstrated practically, the high stakes of their respective shortcomings is hindering the wide spread application of these methods. Thus different solid state storage materials are being looked upon as promising solutions. Metal hydrides are a class of solid state hydrogen storage materials which are formed by the reaction of metals or their alloys with hydrogen. These materials have very good gravimetric storage densities, but are very stable thermodynamically to desorp hydrogen at room temperatures. Research is going on to improve the thermodynamics and the reaction kinetics of different metal hydrides. This dissertation tries to address the problem of high thermodynamic stability of the existing metal hydrides in two ways. First, a novel carbon based lithium material is proposed as a viable storage option based on its promising thermodynamic heat of formation. Pure beryllium (Be) clusters and the carbon-beryllium (C-Be) clusters are studied in detail using the Density Functional Theory (DFT) computational methods. Their interactions with hydrogen molecule are further studied. The results of these calculations indicate that hydrogen is more strongly physisorbed to the beryllium atom in the C-Be cluster, rather than to a carbon atom. After these initial studies, we calculated the geometries and the energies of more than 100 different carbon based lithium

  13. An elastic mechanics model and computation method for geotechnical material

    Institute of Scientific and Technical Information of China (English)

    Zheng Yingren; Gao Hong; Zheng Lushi


    Internal friction characteristic is one of the basic properties of geotechnical materials and it exists in mechanical elements all the time.However,until now internal friction is only considered in limit analysis and plastic mechanics but not included in elastic theory for rocks and soils.We consider that internal friction exists in both elastic state and plastic state of geotechnical materials,so the mechanical unit of friction material is constituted.Based on study results of soil tests,the paper also proposes that cohesion takes effect first and internal friction works gradually with the increment of deformation.By assuming that the friction coefficient is proportional to the strain,the internal friction is computed.At last,by imitating the linear elastic mechanics,the nonlinear elastic mechanics model of friction material is established,where the shear modulus G is not a constant.The new model and the traditional elastic model are used simultaneously to analyze an elastic foundation.The results indicate that the displacements computed by the new model are less than those from the traditional method,which agrees with the fact and shows that the mechanical units of friction material are suitable for geotechnical material.

  14. Computation of Piezo-electric Materials


    Song, Seung Yun; García, R. Edwin


    Piezo -electric materials are materials that will change its shape and size when an electric field is applied to the material. Vice versa, these materials will generate a certain voltage when they are bent, vibrated, or deformed. These materials show promising future , because they link mechanical and electrical properties of a material. In 21st century when electronic devices such as smart phones or touch-screen TV’s depend highly on mechanical input such as human’s touch, developing and res...

  15. Application and prospect of computer technology in welding materials field

    Institute of Scientific and Technical Information of China (English)


    This paper summarizes the application status of computer technology in welding materials field from three aspects: the CAD of welding materials, the date base system for welding materials and the expert system for welding materials .Besides, this paper explores and discusses the existing problems and the developing trend in the future.

  16. Wear predictions for UHMWPE material with various surface properties used on the femoral component in total knee arthroplasty: a computational simulation study. (United States)

    Kang, Kyoung-Tak; Son, Juhyun; Kim, Ho-Joong; Baek, Changhyun; Kwon, Oh-Ryong; Koh, Yong-Gon


    The wear of ultrahigh-molecular weight polyethylene (UHMWPE) tibial inserts in total knee arthroplasty (TKA) remains a major limitation that hinders the longevity of clinically successful devices. Surface properties significantly affect the overall performance of TKA, and surface modification with mechanically and chemically stable materials is an effective method for overcoming the wear of TKA. However, wear tests are not cost-efficient or time-efficient; thus, the effects of geometric, loading, and alignment perturbations are often evaluated via parametric studies. Computational wear prediction using a finite element (FE) model followed by validation through comparison with experimental data is effective for assessing new prosthetic designs or surface change methods prior to functional testing and surgical implementation. The aim of this study was to evaluate the weight loss, wear depth, and kinematics for different surface properties, including nanostructured diamond (NSD), diamond-like carbon (DLC), titanium-nitride (TiN), and oxidized zirconium (OxZr) on femoral components in TKA using FE analysis under gait-cycle loading conditions. Weight loss and wear depth were lowest with OxZr followed by TiN, NSD, and DLC. However, the DLC femoral component did not show any improvement in wear rate compared to an uncoated cobalt-chromium (Co-Cr) femoral component. Not all surface changes applied in this study did lead to improvement in wear performance. However, this study demonstrates the potential of OxZr and TiN for reducing UHMWPE wear and offers new insights into the effects of wear on TKA.

  17. Designing with an underdeveloped computational composite for materials experience

    NARCIS (Netherlands)

    Barati, B.; Karana, E.; Hekkert, P.P.M.; Jönsthövel, I.


    In response to the urge for multidisciplinary development of computational composites, designers and material scientists are increasingly involved in collaborative projects to valorize these technology-push materials in the early stages of their development. To further develop the computational com

  18. Efficacy of ProTaper NEXT Compared with Reciproc in Removing Obturation Material from Severely Curved Root Canals: A Micro-Computed Tomography Study. (United States)

    Nevares, Giselle; de Albuquerque, Diana S; Freire, Laila G; Romeiro, Kaline; Fogel, Howard M; Dos Santos, Marcelo; Cunha, Rodrigo S


    The aim of this study was to compare the remaining root canal obturation, volume of dentin removed, and apical transportation after retreatment of severely curved root canals by using Reciproc (REC) or ProTaper NEXT (PTN) systems. Twenty-eight mesial canals of mandibular molars were instrumented and then obturated with gutta-percha and sealer and allocated into 2 balanced groups (n = 14), the REC group (R25 file) and the PTN group (X3 and X2 files). Micro-computed tomography analysis was performed to assess the percentage of residual obturation material, the amount of dentin removed, and apical transportation. The effective time for the removal of obturation and procedural errors were recorded. Obturation was effectively removed from the root canal in the REC and PTN groups (P ≤ .001), and the percentages of remaining obturation material were similar between both groups (84.8% PTN vs 86.5% REC) (P > .05). The amount of dentin removed (3.17 ± 2.64 mm(3) PTN versus 3.50 ± 2.82 mm(3) REC), apical transportation (at 1 mm: 0.096 ± 0.189 mm PTN versus 0.093 ± 0.186 mm REC; at 3 mm: 0.059 ± 0.069 mm PTN versus 0.082 ± 0.080 mm REC; at 5 mm: 0.097 ± 0.093 mm PTN versus 0.133 ± 0.138 mm REC), and the working time (269.69 ± 19.25 seconds PTN versus 268.62 ± 16.37 seconds REC) were also similar in both groups (P > .05). One file fractured in the REC group. Both systems were equally effective in the removal of obturation from severely curved canals and can be used for retreatment. Neither system could completely remove the obturation material; therefore, additional techniques are needed to improve cleaning of the root canal. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  19. Computational thermodynamics and informational technologies in the field of computer design of materials

    Directory of Open Access Journals (Sweden)

    Udovsky A.L.


    Full Text Available Computational thermodynamics and informational technologies in the field of computer desing of materials as well as appliance of CALPHAD method on resolution of thermodynamic problems are presented in this paper.

  20. Computational Age Dating of Special Nuclear Materials

    Energy Technology Data Exchange (ETDEWEB)

    None, None


    This slide-show presented an overview of the Constrained Progressive Reversal (CPR) method for computing decays, age dating, and spoof detecting. The CPR method is: Capable of temporal profiling a SNM sample; Precise (compared with known decay code, such a ORIGEN); Easy (for computer implementation and analysis). We have illustrated with real SNM data using CPR for age dating and spoof detection. If SNM is pure, may use CPR to derive its age. If SNM is mixed, CPR will indicate that it is mixed or spoofed.

  1. Computational Design of Ageless Structural Materials Project (United States)

    National Aeronautics and Space Administration — Crack initiation and propagation is a dominant failure mode for many materials and applications – usually managed via damage tolerance approaches." ...

  2. Prospective Mathematics Teachers' Views about Using Computer-Based Instructional Materials in Constructing Mathematical Concepts (United States)

    Bukova-Guzel, Esra; Canturk-Gunhan, Berna


    The purpose of the study is to determine prospective mathematics teachers' views about using computer-based instructional materials in constructing mathematical concepts and to reveal how the sample computer-based instructional materials for different mathematical concepts altered their views. This is a qualitative study involving twelve…

  3. Computational Methods for Material Failure Processes (United States)


    Belytschko, "Advances in Computational Mechanics," Nuclear Engineering and Design, 134, pp. 1-22, 1992. T. Belytschko and N. D. Gilbertsen, " along the normal direction. 50 N4 N3 N4 N? N3 N4 N3 .41 Fision NS ’, Mz 46 Fusion NI NZ NI NS NZ NI NZ iM MI MZ Mi NI NZ Ni N3 NZ NI NZ Fig. 2.1

  4. 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)


    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.

  5. Computer-Mediated Materials for Chinese Character Learning. (United States)

    Hsu, Hui-Mei; Gao, Liwei


    Reviews four sets of computer-mediated materials for Chinese character learning. These include the following: Write Chinese, Chinese Characters Primer, Animated Chinese Characters, and USC Chinese Character Page. (Author/VWL)

  6. Computational Search for Improved Ammonia Storage Materials

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Lysgaard, Steen; Vegge, Tejs

    Metal halide ammines, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can reversibly store ammonia, with high volumetric hydrogen storage capacities. The storage in the halide ammines is very safe, and the salts are therefore highly relevant as a carbon-free energy carrier in future transportation infrastructure....... In this project we are searching for improved mixed materials with optimal desorption temperatures and kinetics, optimally releasing all ammonia in one step. We apply Density Functional Theory, DFT, calculations on mixed compounds selected by a Genetic Algorithm (GA), relying on biological principles of natural...

  7. Computationally Driven Two-Dimensional Materials Design: What Is Next?

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Jie [Materials Science; Lany, Stephan [Materials Science; Qi, Yue [Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, United States


    Two-dimensional (2D) materials offer many key advantages to innovative applications, such as spintronics and quantum information processing. Theoretical computations have accelerated 2D materials design. In this issue of ACS Nano, Kumar et al. report that ferromagnetism can be achieved in functionalized nitride MXene based on first-principles calculations. Their computational results shed light on a potentially vast group of materials for the realization of 2D magnets. In this Perspective, we briefly summarize the promising properties of 2D materials and the role theory has played in predicting these properties. In addition, we discuss challenges and opportunities to boost the power of computation for the prediction of the 'structure-property-process (synthesizability)' relationship of 2D materials.

  8. Graphics and composite material computer program enhancements for SPAR (United States)

    Farley, G. L.; Baker, D. J.


    User documentation is provided for additional computer programs developed for use in conjunction with SPAR. These programs plot digital data, simplify input for composite material section properties, and compute lamina stresses and strains. Sample problems are presented including execution procedures, program input, and graphical output.

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

    CERN Document Server

    Jorissen, Kevin; Rehr, John J


    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 traditi...

  10. Instructional Computing: Ten Case Studies. (United States)

    Hargan, Carol; Hunter, Beverly

    These case studies are written for educational institutions that wish to plan, extend, or improve their use of computers for learning and teaching. Each case study includes a brief description of each of the following: profile of the institution, history of the development of instructional computing, organization and management, student access to…

  11. Information and computer-aided system for structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Nekrashevitch, Yu.G.; Nizametdinov, Sh.U.; Polkovnikov, A.V.; Rumjantzev, V.P.; Surina, O.N. (Engineering Physics Inst., Moscow (Russia)); Kalinin, G.M.; Sidorenkov, A.V.; Strebkov, Yu.S. (Research and Development Inst. of Power Engineering, Moscow (Russia))


    An information and computer-aided system for structural materials data has been developed to provide data for the fusion and fission reactor system design. It is designed for designers, industrial engineers, and material science specialists and provides a friendly interface in an interactive mode. The database for structural materials contains the master files: Chemical composition, physical, mechanical, corrosion, technological properties, regulatory and technical documentation. The system is implemented on a PC/AT running the PS /2 operating system. (orig.).

  12. Computer-Aided Process Model For Carbon/Phenolic Materials (United States)

    Letson, Mischell A.; Bunker, Robert C.


    Computer program implements thermochemical model of processing of carbon-fiber/phenolic-matrix composite materials into molded parts of various sizes and shapes. Directed toward improving fabrication of rocket-engine-nozzle parts, also used to optimize fabrication of other structural components, and material-property parameters changed to apply to other materials. Reduces costs by reducing amount of laboratory trial and error needed to optimize curing processes and to predict properties of cured parts.

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

    Energy Technology Data Exchange (ETDEWEB)



    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.

  14. Characterization of Meta-Materials Using Computational Electromagnetic Methods (United States)

    Deshpande, Manohar; Shin, Joon


    An efficient and powerful computational method is presented to synthesize a meta-material to specified electromagnetic properties. Using the periodicity of meta-materials, the Finite Element Methodology (FEM) is developed to estimate the reflection and transmission through the meta-material structure for a normal plane wave incidence. For efficient computations of the reflection and transmission over a wide band frequency range through a meta-material a Finite Difference Time Domain (FDTD) approach is also developed. Using the Nicholson-Ross method and the Genetic Algorithms, a robust procedure to extract electromagnetic properties of meta-material from the knowledge of its reflection and transmission coefficients is described. Few numerical examples are also presented to validate the present approach.

  15. Crack Propagation in Honeycomb Cellular Materials: A Computational Approach

    Directory of Open Access Journals (Sweden)

    Marco Paggi


    Full Text Available Computational models based on the finite element method and linear or nonlinear fracture mechanics are herein proposed to study the mechanical response of functionally designed cellular components. It is demonstrated that, via a suitable tailoring of the properties of interfaces present in the meso- and micro-structures, the tensile strength can be substantially increased as compared to that of a standard polycrystalline material. Moreover, numerical examples regarding the structural response of these components when subjected to loading conditions typical of cutting operations are provided. As a general trend, the occurrence of tortuous crack paths is highly favorable: stable crack propagation can be achieved in case of critical crack growth, whereas an increased fatigue life can be obtained for a sub-critical crack propagation.

  16. Soft computing in design and manufacturing of advanced materials (United States)

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


    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.

  17. Materials for Alternative Energies: Computational Materials Discovery and Crystal Structure Prediction (United States)

    Wolverton, Chris


    Many of the key technological problems associated with alternative energies may be traced back to the lack of suitable materials. The materials discovery process may be greatly aided by the use of computational methods, particular those atomistic methods based on density functional theory. In this talk, we present an overview of recent work on energy-related materials from density-functional based approaches. We have developed novel computational tools which enable accurate prediction of crystal structures for new materials (using both Monte Carlo and Genetic Algorithm based approaches), materials discovery via high-throughput, data mining techniques, and automated phase diagram calculations. We highlight applications in the area of Li battery materials and hydrogen storage materials.

  18. Material reconstruction for spectral computed tomography with detector response function (United States)

    Liu, Jiulong; Gao, Hao


    Different from conventional computed tomography (CT), spectral CT using energy-resolved photon-counting detectors is able to provide the unprecedented material compositions. However accurate spectral CT needs to account for the detector response function (DRF), which is often distorted by factors such as pulse pileup and charge-sharing. In this work, we propose material reconstruction methods for spectral CT with DRF. The simulation results suggest that the proposed methods reconstructed more accurate material compositions than the conventional method without DRF. Moreover, the proposed linearized method with linear data fidelity from spectral resampling had improved reconstruction quality from the nonlinear method directly based on nonlinear data fidelity.

  19. The Computational Study of Vision. (United States)


    provide only partial information about the 2-D velocity field, due to the aperture problem (Wallach, 1976; Fennema and Thompson, 1979; Burt vision studies and in biological models of motion measurement (for example, Lappin and Bell, 1976; Pantle and Picciano, 1976; Fennema and...830. Fennema , C. L., Thompson, W. B. 1979. Velocity determination in scenes containing several moving objects. Comput. Graph. Image Proc. 9:301-315

  20. Associated computational plasticity schemes for nonassociated frictional materials

    DEFF Research Database (Denmark)

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


    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...

  1. Continuous Materiality: Through a Hierarchy of Computational Codes

    Directory of Open Access Journals (Sweden)

    Jichen Zhu


    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.

  2. Feasibility study: PASS computer environment

    Energy Technology Data Exchange (ETDEWEB)



    The Policy Analysis Screening System (PASS) is a computerized information-retrieval system designed to provide analysts in the Department of Energy, Assistant Secretary for Environment, Office of Technology Impacts (DOE-ASEV-OTI) with automated access to articles, computer simulation outputs, energy-environmental statistics, and graphics. Although it is essential that PASS respond quickly to user queries, problems at the computer facility where it was originally installed seriously slowed PASS's operations. Users attempting to access the computer by telephone repeatedly encountered busy signals and, once logged on, experienced unsatisfactory delays in response to commands. Many of the problems stemmed from the system's facility manager having brought another large user onto the system shortly after PASS was implemented, thereby significantly oversubscribing the facility. Although in March 1980 Energy Information Administration (EIA) transferred operations to its own computer facility, OTI has expressed concern that any improvement in computer access time and response time may not be sufficient or permanent. Consequently, a study was undertaken to assess the current status of the system, to identify alternative computer environments, and to evaluate the feasibility of each alternative in terms of its cost and its ability to alleviate current problems.

  3. Computational Discovery of Novel Hydrogen Storage Materials and Reactions (United States)

    Wolverton, Christopher


    Practical hydrogen storage for mobile applications requires materials that exhibit high hydrogen densities, low decomposition temperatures, and fast kinetics for absorption and desorption. Unfortunately, no reversible materials are currently known that possess all of these attributes. Here we present an overview of our recent efforts aimed at developing a first-principles computational approach to the discovery of novel hydrogen storage materials. We have developed computational tools which enable accurate prediction of decomposition thermodynamics, crystal structures for unknown hydrides, and thermodynamically preferred decomposition pathways. We present examples that illustrate each of these three capabilities. Specifically, we focus on recent work on crystal structure and dehydriding reactions of borohydride materials, such as Mg(BH4)2, MgB12H12, and mixtures of complex hydrides such as the ternary LiBH4/LiNH2/MgH2 system.References:[0pt] (1) V. Ozolins, E. H. Majzoub, and C. Wolverton, ``First-Principles Prediction of a Ground State Crystal Structure of Magnesium Borohydride'', Phys. Rev. Lett. 100, 135501 (2008).(2) C. Wolverton, D. J. Siegel, A. R. Akbarzadeh, and V. Ozolins, ``Discovery of Novel Hydrogen Storage Materials: An Atomic Scale Computational Approach'', J. Phys. Condens. Matt. 20, 064228 (2008).(3) J. Yang, et al., ``A Self-Catalyzing Hydrogen Storage Material'' Angew. Chem. Int. Ed., 47, 882 (2008).(4) A. R. Akbarzadeh, V. Ozolins, and C. Wolverton, ``First-Principles Determination of Multicomponent Hydride Phase Diagrams: Application to the Li-Mg-N-H System'', Advanced Materials 19, 3233 (2007).(5) D. J. Siegel, C. Wolverton, and V. Ozolins, ``Thermodynamic Guidelines for the Prediction of Hydrogen Storage Reactions and their Application to Destabilized Hydride Mixtures'', Phys. Rev. B 76, 134102 (2007).

  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


    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. One Kind of Teaching Methodology of Computer Curriculum for Case-study Teaching Materials%基于案例教程的计算机课程教学方法探析

    Institute of Scientific and Technical Information of China (English)

    叶昆权; 兰丽


    本文分析了案例教程教学方法探究的必要性。提出了一种符合人类认识事物基本规律的基于案例教程的计算机课程教学方法,并用实例阐述了其关键步骤。最后指出案例教程选取的基本原则,提出对改进教学方法的展望。%The article analyzed the necessity of looking for the teaching methodology for case-study teaching materials,put forward one kind of teaching methodology of computer curriculum for case-study teaching materials,the methodology accorded with the law of cog

  6. Balanced technology initiative on computational mechanics of materials (United States)

    Asaro, Robert J.


    The goal of this project, which was part of the DARPA Balanced Technology Initiative on Computational Mechanics, was to develop a comprehensive approach to the numerical modeling of the mechanical behavior of materials. Particular areas for focus in the project were the inelastic deformation of highly anisotropic materials such as single crystals and textured polycrystals, as well as evolving microstructural damage in ceramics and ductile metals in both slow and high rate deformation processes. While the contract was awarded for a period of three years, it was actually funded only for the first year. Nonetheless, significant progress can be reported as a direct result of this project.

  7. Computer-Aided Design Of Sheet-Material Parts (United States)

    Gilbert, Jeffrey L.; Paternoster, Vincent Y.; Levitt, Maureen L.; Osterloh, Mark R.


    Computer-aided-design system partly automates tedious process of designing and guiding assembly of small pieces of flat sheet material into large surfaces that approximate smoothly curved surfaces having complicated three-dimensional shapes. Capability provides for flexibility enabling designer to assess quickly and easily effects of changes in design in making engineering compromises among various sizes and shapes. Saves time and money in both design and fabrication. Used in rocket-engine application and other applications requiring design of sheet-material parts.

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

    CERN Document Server

    Trovalusci, Patrizia


    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.

  9. Computational modelling of cohesive cracks in material structures (United States)

    Vala, J.; Jarošová, P.


    Analysis of crack formation, considered as the creation of new surfaces in a material sample due to its microstructure, leads to nontrivial physical, mathematical and computational difficulties even in the rather simple case of quasistatic cohesive zone modelling inside the linear elastic theory. However, quantitative results from such evaluations are required in practice for the development and design of advanced materials, structures and technologies. Although most available software tools apply ad hoc computational predictions, this paper presents the proper formulation of such model problem, including its verification, and sketches the more-scale construction of finite-dimensional approximation of solutions, utilizing the finite element or similar techniques, together with references to original simulations results from engineering practice.

  10. Computational Studies of Glutamate Transporters

    Directory of Open Access Journals (Sweden)

    Jeffry Setiadi


    Full Text Available Glutamate is the major excitatory neurotransmitter in the human brain whose binding to receptors on neurons excites them while excess glutamate are removed from synapses via transporter proteins. Determination of the crystal structures of bacterial aspartate transporters has paved the way for computational investigation of their function and dynamics at the molecular level. Here, we review molecular dynamics and free energy calculation methods used in these computational studies and discuss the recent applications to glutamate transporters. The focus of the review is on the insights gained on the transport mechanism through computational methods, which otherwise is not directly accessible by experimental probes. Recent efforts to model the mammalian glutamate and other amino acid transporters, whose crystal structures have not been solved yet, are included in the review.

  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


    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. Adhesive Bonding to Computer-aided Design/ Computer-aided Manufacturing Esthetic Dental Materials: An Overview. (United States)

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


    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.

  13. Semi-analytical computation of displacement in linear viscoelastic materials (United States)

    Spinu, S.; Gradinaru, D.


    Prediction of mechanical contact performance based on elastic models is not accurate in case of viscoelastic materials; however, a closed-form description of the viscoelastic contact has yet to be found. This paper aims to advance a semi-analytical method for computation of displacement induced in viscoelastic materials by arbitrary surface tractions, as a prerequisite to a semi-analytical solution for the viscoelastic contact problem. The newly advanced model is expected to provide greater generality, allowing for arbitrary contact geometry and / or arbitrary loading history. While time-independent equations in the purely elastic model can be treated numerically by imposing a spatial discretization only, a viscoelastic constitutive law requires supplementary temporal discretization capable of simulating the memory effect specific to viscoelastic materials. By deriving new influence coefficients, computation of displacement induced in a viscoelastic material by a known but otherwise arbitrary history of surface tractions can be achieved via superposition authorized by the Boltzmann superposition theory applicable in the frame of linear viscoelasticity.

  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)


    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. Assessing computer waste generation in Chile using material flow analysis. (United States)

    Steubing, Bernhard; Böni, Heinz; Schluep, Mathias; Silva, Uca; Ludwig, Christian


    The quantities of e-waste are expected to increase sharply in Chile. The purpose of this paper is to provide a quantitative data basis on generated e-waste quantities. A material flow analysis was carried out assessing the generation of e-waste from computer equipment (desktop and laptop PCs as well as CRT and LCD-monitors). Import and sales data were collected from the Chilean Customs database as well as from publications by the International Data Corporation. A survey was conducted to determine consumers' choices with respect to storage, re-use and disposal of computer equipment. The generation of e-waste was assessed in a baseline as well as upper and lower scenarios until 2020. The results for the baseline scenario show that about 10,000 and 20,000 tons of computer waste may be generated in the years 2010 and 2020, respectively. The cumulative e-waste generation will be four to five times higher in the upcoming decade (2010-2019) than during the current decade (2000-2009). By 2020, the shares of LCD-monitors and laptops will increase more rapidly replacing other e-waste including the CRT-monitors. The model also shows the principal flows of computer equipment from production and sale to recycling and disposal. The re-use of computer equipment plays an important role in Chile. An appropriate recycling scheme will have to be introduced to provide adequate solutions for the growing rate of e-waste generation.

  16. Computer-aided selection of materials for cryogenic turbopump bearings (United States)

    Maurer, R. E.; Pallini, R. A.


    The life requirement for the angular contact ball bearings in the Space Shuttle Main Engine (SSME) high-pressure-oxygen turbopump (HPOTP) is 7.5 hours. In actual operation, significantly shorter service life has been experienced. The objective of this current program is to identify bearing materials and/or materials processing techniques offering significant potential for extending HPOTP bearing performance life. A thermomechanical analysis of the HPOTP shaft/bearing system was performed with the SHABERTH (SHaft-BEaring-THermal) computer program. Bearing fatigue life, ball-race contact stress, heat generation rate, bulk ring temperatures, and circumferential stress in the inner rings were quantified as functions of radial load, thrust load, and ball-race contact friction. The analysis results were used to formulate criteria that are being used for the selection of special materials for future turbopump bearings.

  17. Research Update: Computational materials discovery in soft matter

    Directory of Open Access Journals (Sweden)

    Tristan Bereau


    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.

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

    CERN Document Server


    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.

  19. Research Update: Computational materials discovery in soft matter (United States)

    Bereau, Tristan; Andrienko, Denis; Kremer, Kurt


    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.

  20. Computational evaluation of optoelectronic properties for organic/carbon materials. (United States)

    Shuai, Zhigang; Wang, Dong; Peng, Qian; Geng, Hua


    CONSPECTUS: Organic optoelectronic materials are used in a variety of devices, including light-emitting diodes, field-effect transistors, photovoltaics, thermoelectrics, spintronics, and chemico- and biosensors. The processes that determine the intrinsic optoelectronic properties occur either in the photoexcited states or within the electron-pumped charged species, and computations that predict these optical and electrical properties would help researchers design new materials. In this Account, we describe recent advances in related density functional theory (DFT) methods and present case studies that examine the efficiency of light emission, carrier mobility, and thermoelectric figures of merit by calculation of the electron-vibration couplings. First we present a unified vibrational correlation function formalism to evaluate the excited-state radiative decay rate constant kr, the nonradiative decay rate constant knr, the intersystem crossing rate constant kISC, and the optical spectra. The molecular parameters that appear in the formalism, such as the electronic excited-state energy, vibrational modes, and vibronic couplings, require extensive DFT calculations. We used experiments for anthracene at both low and ambient temperatures to benchmark the calculated photophysical parameters. In the framework of Fermi's golden rule, we incorporated the non-adiabatic coupling and the spin-orbit coupling to evaluate the phosphorescence efficiency and emission spectrum. Both of these are in good agreement with experimental results for anthracene and iridium compounds. Band electron scattering and relaxation processes within Boltzmann theory can describe charge transport in two-dimensional carbon materials and closely packed organic solids. For simplicity, we considered only the acoustic phonon scattering as modeled by the deformation potential approximation coupled with extensive DFT calculations for band structures. We then related the carrier mobility to the band

  1. Biology Teacher and Expert Opinions about Computer Assisted Biology Instruction Materials: A Software Entitled Nucleic Acids and Protein Synthesis (United States)

    Hasenekoglu, Ismet; Timucin, Melih


    The aim of this study is to collect and evaluate opinions of CAI experts and biology teachers about a high school level Computer Assisted Biology Instruction Material presenting computer-made modelling and simulations. It is a case study. A material covering "Nucleic Acids and Protein Synthesis" topic was developed as the…

  2. Computational Tools and Studies of Graphene Nanostructures

    DEFF Research Database (Denmark)

    Papior, Nick Rübner

    Nano-electronics industry has during the past decade decreased feature sizes to roughly 10nm. Such feature sizes are at the quantum limit, requiring a description at the quantum mechanical level. Parallel to the experimental work reside the theoretical tools used to investigate and understand...... such systems. These theoretical tools still have a high computational requirement. Thus more efficient algorithms are needed to perform studies on even larger systems. Although the gap between the theoretical tools and the experimental setups are reduced, there is still a gap, and the used theoretical methods...... 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...

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

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


    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 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. Computational modeling of heterogeneous reactive materials at the mesoscale (United States)

    Baer, M. R.


    The mesoscopic processes of consolidation, deformation and reaction of shocked porous energetic materials are studied using shock physics analysis of impact on a collection of discrete "crystals." Highly resolved three-dimensional CTH simulations indicate that rapid deformation occurs at material contact points causing large amplitude fluctuations of stress states with wavelengths of the order of several particle diameters. Localization of energy produces "hot-spots" due to shock focusing and plastic work near internal boundaries as material flows into interstitial regions. Numerical experiments indicate that "hot-spots" are strongly influenced by multiple crystal interactions. Chemical reaction processes also produce multiple wave structures associated with particle distribution effects. This study provides new insights into the micromechanical behavior of heterogeneous energetic materials strongly suggesting that initiation and sustained reaction of shocked heterogeneous materials involves states distinctly different from single jump state descriptions.

  5. CAD/CAM (Computer Aided Design/Computer Aided Manufacture). A Brief Guide to Materials in the Library of Congress. (United States)

    Havas, George D.

    This brief guide to materials in the Library of Congress (LC) on computer aided design and/or computer aided manufacturing lists reference materials and other information sources under 13 headings: (1) brief introductions; (2) LC subject headings used for such materials; (3) textbooks; (4) additional titles; (5) glossaries and handbooks; (6)…

  6. Huntington Computer Project: A Teacher's Manual (Computer-Related Materials). Second Edition. (United States)

    State Univ. of New York, Stony Brook. Huntington Computer Project.

    A compilation of BASIC computer programs developed by teachers and students involved in the Huntington Computer Project is presented. The programs are grouped by subject area. The six subject areas are biology, earth science, chemistry mathematics, physics, social studies, and teacher assistance. For each program, the following information is…

  7. Computation of multi-material interactions using point method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Duan Z [Los Alamos National Laboratory; Ma, Xia [Los Alamos National Laboratory; Giguere, Paul T [Los Alamos National Laboratory


    Calculations of fluid flows are often based on Eulerian description, while calculations of solid deformations are often based on Lagrangian description of the material. When the Eulerian descriptions are used to problems of solid deformations, the state variables, such as stress and damage, need to be advected, causing significant numerical diffusion error. When Lagrangian methods are used to problems involving large solid deformat ions or fluid flows, mesh distortion and entanglement are significant sources of error, and often lead to failure of the calculation. There are significant difficulties for either method when applied to problems involving large deformation of solids. To address these difficulties, particle-in-cell (PIC) method is introduced in the 1960s. In the method Eulerian meshes stay fixed and the Lagrangian particles move through the Eulerian meshes during the material deformation. Since its introduction, many improvements to the method have been made. The work of Sulsky et al. (1995, Comput. Phys. Commun. v. 87, pp. 236) provides a mathematical foundation for an improved version, material point method (MPM) of the PIC method. The unique advantages of the MPM method have led to many attempts of applying the method to problems involving interaction of different materials, such as fluid-structure interactions. These problems are multiphase flow or multimaterial deformation problems. In these problems pressures, material densities and volume fractions are determined by satisfying the continuity constraint. However, due to the difference in the approximations between the material point method and the Eulerian method, erroneous results for pressure will be obtained if the same scheme used in Eulerian methods for multiphase flows is used to calculate the pressure. To resolve this issue, we introduce a numerical scheme that satisfies the continuity requirement to higher order of accuracy in the sense of weak solutions for the continuity equations

  8. Computational Design and Characterization of New Battery Materials

    DEFF Research Database (Denmark)

    Mýrdal, Jón Steinar Garðarsson

    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...... studies for new materials, as well as to more detailed investigations on interesting properties of different battery components. In the screening studies simple predictors are used to search for desired material properties and reduce the number of materials that need to be studied in more detail. Solid...... 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    LeSar, R.


    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.

  10. Computational Modeling of Ultrafast Pulse Propagation in Nonlinear Optical Materials (United States)

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


    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.

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

    CERN Document Server

    Runge, Keith; Muralidharan, Krishna


    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.

  12. Global Seabed Materials and Habitats Mapped: The Computational Methods (United States)

    Jenkins, C. J.


    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.

  13. Ranking the stars: a refined Pareto approach to computational materials design. (United States)

    Lejaeghere, Kurt; Cottenier, Stefaan; Van Speybroeck, Veronique


    We propose a procedure to rank the most interesting solutions from high-throughput materials design studies. Such a tool is becoming indispensable due to the growing size of computational screening studies and the large number of criteria involved in realistic materials design. As a proof of principle, the binary tungsten alloys are screened for both large-weight and high-impact materials, as well as for fusion reactor applications. Moreover, the concept is generally applicable to any design problem where multiple competing criteria have to be optimized.

  14. Studi Perbandingan Layanan Cloud Computing

    Directory of Open Access Journals (Sweden)

    Afdhal Afdhal


    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. Opinions Of Teachers’ Employed In Vocational and Technical Education Institutions About Computer and Internet Based Teaching Materials Usage

    Directory of Open Access Journals (Sweden)

    Özgen KORKMAZ


    Full Text Available The purpose of this research is to identify the vocational and technical educational scool teachers’ usage level of computer and internet based instructional material in their courses. A qualitative research design was used in this study. The candidates are from four different vocational schools constituting a total of 49 vocational teachers who are working Kırşehir, Turkey. To collect the data, the teachers were asked four open-ended questions about their level of computer and internet based instructional material usage in their courses and about their views through an interview form. The data obtained are analyzed by means of document review and some of the results are as follows: The majority of teachers express that they use computer and internet based instructional materials in their courses, but the usage level is not adequate. According to teachers, the primary reason for inadequate usage of computer and internet based instructional materials is insufficient material and old computer hardware.

  16. Computational design of materials for solar hydrogen generation (United States)

    Umezawa, Naoto

    Photocatalysis has a great potential for the production of hydrogen from aquerous solution under solar light. In this talk, two different approaches toward the computational materials desing for solar hydrogen generation will be presented. Tin (Sn), which has two major oxidation states, Sn2+ and Sn4+, is abundant on the earth's crust. Recently, visible-light responsive photocatalytc H2 evolution reaction was identified over a mixed valence tin oxide Sn3O4. We have carried out crystal structure prediction for mixed valence tin oxides in different atomic compositions under ambient pressure condition using advanced computational methods based on the evolutionary crystal-structure search and density-functional theory. The predicted novel crystal structures realize the desirable band gaps and band edge positions for H2 evolution under visible light irradiation. It is concluded that multivalent tin oxides have a great potential as an abundant, cheap and environmentally-benign solar-energy conversion photofunctional materials. Transition metal doping is effective for sensitizing SrTiO3 under visible light. We have theoretically investigated the roles of the doped Cr in STO based on hybrid density-functional calculations. Cr atoms are preferably substituting for Ti under any equilibrium growth conditions. The lower oxidation state Cr3+, which is stabilized under an n-type condition of STO, is found to be advantageous for the photocatalytic performance. It is firther predicted that lanthanum is the best codopant for stabilizing the favorable oxidation state, Cr3+. The prediction was validated by our experiments that La and Cr co-doped STO shows the best performance among examined samples. This work was supported by the Japan Science and Technology Agency (JST) Precursory Research for Embryonic Science and Technology (PRESTO) and International Research Fellow program of Japan Society for the Promotion of Science (JSPS) through project P14207.

  17. A micromorphic computational homogenization framework for heterogeneous materials (United States)

    Biswas, R.; Poh, L. H.


    The conventional first-order computational homogenization framework is restricted to problems where the macro characteristic length scale is much larger than the underlying Representative Volume Element (RVE). In the absence of a clear separation of length scales, higher-order enrichment is required to capture the influence of the underlying rapid fluctuations, otherwise neglected in the first-order framework. In this contribution, focusing on matrix-inclusion composites, a novel computational homogenization framework is proposed such that standard continuum models at the micro-scale translate onto the macro-scale to recover a micromorphic continuum. Departing from the conventional FE2 framework where a macroscopic strain tensor characterizes the average deformation within the RVE, our formulation introduces an additional macro kinematic field to characterize the average strain in the inclusions. The two macro kinematic fields, each characterizing a particular aspect of deformation within the RVE, thus provide critical information on the underlying rapid fluctuations. The net effect of these fluctuations, as well as the interactions between RVEs, are next incorporated naturally into the macroscopic virtual power statement through the Hill-Mandel condition. The excellent predictive capability of the proposed homogenization framework is illustrated through three benchmark examples. It is shown that the homogenized micromorphic model adequately captures the material responses, even in the absence of a clear separation of length scales between macro and micro.

  18. An Investigation on Teaching Materials Used in Social Studies Lesson (United States)

    Saglam, Halil Ibrahim


    The purpose of this study is to analyze the teaching materials employed during social studies lessons on the basis of certain variables. Specifically, the researcher tried to find out whether teachers' gender, service length, having a personal computer, receiving an in-service training regarding the use of teaching materials, having an interest on…

  19. EXAFS studies of crystalline materials

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, G.S.; Georgopoulos, P.


    The application of extended x-ray absorption fine structure (EXAFS) technique to the study of crystalline materials is discussed, and previously published work on the subject is reviewed with 46 references being cited. The theory of EXAFS, methods of data analysis, and the experimental techniques, including those based on synchrotron and laboratory facilities are all discussed. Absorption and fluorescence methods of detecting EXAFS also receive attention. (BLM)

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

    DEFF Research Database (Denmark)

    Mishnaevsky, Leon


    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....

  1. Computational Comminution and Its Key Technologies Applied to Materials Processing Procedure

    Institute of Scientific and Technical Information of China (English)


    A new concept named computational comminution is proposed in this paper, which is different from the traditional studies on materials processing procedure such as the study based on theoretic models, the study based on experiment models, which is based on information models. Some key technologies applied to materials processing procedure such as artificial neural networks, fuzzy sets, genetic algorithms and visualization technology are also presented, and a fusing methodology of these new technologies is studied. Application in the cement grinding process of Horomill shows that results in this paper are efficient.

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

    Energy Technology Data Exchange (ETDEWEB)



    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.


    Directory of Open Access Journals (Sweden)

    Aprilian Ria Adisti


    Full Text Available This study aims at explaining the interactive materials that were needed in Teaching English to Young Learner, creating an English computer game into an interactive material, and examining the effective of the implementation of an English computer game as an interactive material in Teaching English to Young Learner to the first-grade students of elementary school. The study used Research and Development (R&D adapted from Hutchinson and Water (1987:53-56 and by Borg and Gall (1985. The study had seven stages, they were: (1 conducting a need analysis of the first-grade students, (2 writing the course grid such as lesson plan and map of interactive material, (3 developing preliminary form of English computer game, (4 preliminary field testing by English teacher, English learning expert, and ICT learning expert, (5 revising the English computer game, (6 trying out, and (7 writing the final draft of the use of English computer game for Teaching English to Young Learners. The result of the study showed that students got better achievement in learning English. It could be seen from the result between pre-test and post-test using t-test formula. The result showed t value > t table; 7.165 > 2.021, it meant that there was a significant difference between pre-test and post-test. The post-test was higher that pre-test. The mean of pre-test was 65.2 while the mean of post-test was 87.44. It was also strengthened by the result of the interview which concluded that students liked learning English through this interactive material.

  4. Creating an English Computer Game as an Interactive Material in Teaching English to Young Learner (TEYL

    Directory of Open Access Journals (Sweden)

    Aprilian Ria Adisti


    Full Text Available This study aims at explaining the interactive materials that were needed in Teaching English to Young Learner, creating an English computer game into an interactive material, and examining the effective of the implementation of an English computer game as an interactive material in Teaching English to Young Learner to the first-grade students of elementary school. The study used Research and Development (R&D adapted from Hutchinson and Water (1987:53-56 and by Borg and Gall (1985. The study had seven stages, they were: (1 conducting a need analysis of the first-grade students, (2 writing the course grid such as lesson plan and map of interactive material, (3 developing preliminary form of English computer game, (4 preliminary field testing by English teacher, English learning expert, and ICT learning expert, (5 revising the English computer game, (6 trying out, and (7 writing the final draft of the use of English computer game for Teaching English to Young Learners. The result of the study showed that students got better achievement in learning English. It could be seen from the result between pre-test and post-test using t-test formula. The result showed t value > t table; 7.165 > 2.021, it meant that there was a significant difference between pre-test and post-test. The post-test was higher that pre-test. The mean of pre-test was 65.2 while the mean of post-test was 87.44. It was also strengthened by the result of the interview which concluded that students liked learning English through this interactive material.

  5. Computational studies of carbodiimide rings. (United States)

    Damrauer, Robert; Lin, Hai; Damrauer, Niels H


    Computational studies of alicyclic carbodiimides (RN═C═NR) (rings five through twelve) at the MP2/6-31G(d,p)//MP2/6-31G(d,p) level of theory were conducted to locate the transition states between carbodiimides isomers. Transition states for rings six through twelve were found. The RNCNR dihedral angle is ∼0° for even-numbered rings, but deviates from 0° for rings seven, nine, eleven, and twelve. The even- and odd-numbered ring transition states have different symmetry point groups. Cs transition states (even rings) have an imaginary frequency mode that transforms as the asymmetric irreducible representation of the group. C2 transition states (odd rings) have a corresponding mode that transforms as the totally symmetric representation. Intrinsic reaction coordinate analyses followed by energy minimization along the antisymmetric pathways led to enantiomeric pairs. The symmetric pathways give diastereomeric isomers. The five-membered ring carbodiimide is a stable structure, possibly isolable. A twelve-membered ring transition state was found only without applying symmetry constraints (C1). Molecular mechanics and molecular dynamics studies of the seven-, eight-, and nine-membered rings gave additional structures, which were then minimized using ab initio methods. No structures beyond those found from the IRC analyses described were found. The potential for optical resolution of the seven-membered ring is discussed.

  6. Computational design of surfaces, nanostructures and optoelectronic materials (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

  7. Computed Tomography Support for Microgravity Materials Science Experiments (United States)

    Gillies, Donald C.; Engel, H. Peter; Whitaker, Ann F. (Technical Monitor)


    The accurate measurement of density in both liquid and solid samples is of considerable interest to Principal Investigators with materials science experiments slated for the ISS. The work to be described is an innovative application of a conventional industrial nondestructive evaluation instrument. Traditional applications of industrial computed tomography (CT) rely on reconstructing cross sections of large structures to provide two-dimensional planar views which can identify defects such as porosity, or other material anomalies. This has been done on microgravity materials science experiments to check the integrity of ampoule-cartridge assemblies for safety purposes. With a substantially monoenergetic flux, as can be obtained with a radioactive cobalt source, there will be a direct correlation between absorption and density. Under such conditions it then becomes possible to make accurate measurements of density throughout a sample, and even when the sample itself is enclosed within a furnace and a safety required cartridge. Such a system has been installed at Kennedy Space Center (KSC) and is available to PIs to examine samples before and after flight. The CT system is being used to provide density information for two purposes. Firstly, the determination of density changes from liquid to solid is vital information to the PI for purposes of modeling the solidification behavior of his sample, and to engineers who have to design containment ampoules and must allow for shrinkage and other volume changes that may occur during processing. While such information can be obtained by pycnometric measurements, the possibility of using a furnace installed on the CT system enables one to examine potentially dangerous materials having high vapor pressures, while not needing visible access to the material. In addition, uniform temperature can readily be obtained, and the system can be controlled to ramp up, hold, and ramp down while collecting data over a wide range of

  8. Computed Tomography Support for Microgravity Materials Science Experiments (United States)

    Gillies, Donald C.; Engel, H. Peter; Whitaker, Ann F. (Technical Monitor)


    The accurate measurement of density in both liquid and solid samples is of considerable interest to Principal Investigators with materials science experiments slated for the ISS. The work to be described is an innovative application of a conventional industrial nondestructive evaluation instrument. Traditional applications of industrial computed tomography (CT) rely on reconstructing cross sections of large structures to provide two-dimensional planar views which can identify defects such as porosity, or other material anomalies. This has been done on microgravity materials science experiments to check the integrity of ampoule-cartridge assemblies for safety purposes. With a substantially monoenergetic flux, as can be obtained with a radioactive cobalt source, there will be a direct correlation between absorption and density. Under such conditions it then becomes possible to make accurate measurements of density throughout a sample, and even when the sample itself is enclosed within a furnace and a safety required cartridge. Such a system has been installed at Kennedy Space Center (KSC) and is available to PIs to examine samples before and after flight. The CT system is being used to provide density information for two purposes. Firstly, the determination of density changes from liquid to solid is vital information to the PI for purposes of modeling the solidification behavior of his sample, and to engineers who have to design containment ampoules and must allow for shrinkage and other volume changes that may occur during processing. While such information can be obtained by pycnometric measurements, the possibility of using a furnace installed on the CT system enables one to examine potentially dangerous materials having high vapor pressures, while not needing visible access to the material. In addition, uniform temperature can readily be obtained, and the system can be controlled to ramp up, hold, and ramp down while collecting data over a wide range of

  9. Computation material science of structural-phase transformation in casting aluminium alloys (United States)

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


    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.

  10. Radiative property investigation. [digital computer programs for determining bidirectional reflectance of spacecraft materials (United States)

    Scott, R. L., Jr.


    A detailed formulation of radiative heat transfer problems involving the use of bidirectional reflectance is discussed. Except for very simple systems this formulation is very intricate. For this reason and the fact that bidirectional data are scarce, such a formulation is not in common use. However, with the development of the digital computer there have been numerical methods developed for detailed radiative investigations using the bidirectional reflectance. Since computations using bidirectional reflectance are coming into use for spacecraft radiative studies, it is necessary to have reflectance data on the materials involved. Materials that are frequently studied are coatings which are used in controlling the thermal environment of spacecrafts. This study is primarily concerned with the bidirectional reflectance of zinc oxide which is one constituent commonly used for coatings.

  11. TU-A-12A-08: Computing Longitudinal Material Changes in Bone Metastases Using Dual Energy Computed Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Schmidtlein, CR; Hwang, S; Veeraraghavan, H; Fehr, D; Humm, J; Deasy, J [Memorial Sloan Kettering Cancer Center, New York, NY (United States)


    Purpose: This study demonstrates a methodology for tracking changes in metastatic bone disease using trajectories in material basis space in serial dual energy computed tomography (DECT) studies. Methods: This study includes patients with bone metastases from breast cancer that had clinical surveillance CT scans using a General Electric CT750HD in dual energy mode. A radiologist defined regions-of-interested (ROI) for bone metastasis, normal bone, and marrow across the serial DECT scans. Our approach employs a Radon transform to forward-projection the basis images, namely, water and iodine, into sinogram space. This data is then repartitioned into fat/bone and effective density/Z image pairs using assumed energy spectrums for the x-ray energies. This approach both helps remove negative material densities and avoids adding spectrum-hardening artifacts. These new basis data sets were then reconstructed via filtered back-projection to create new material basis pair images. The trajectories of these pairs were then plotted in the new basis space providing a means to both visualize and quantitatively measure changes in the material properties of the tumors. Results: ROI containing radiologist defined metastatic bone disease showed well-defined trajectories in both fat/bone and effective density/Z space. ROI that contained radiologist defined normal bone and marrow did not exhibit any discernible trajectories and were stable from scan to scan. Conclusions: The preliminary results show that changes in material composition and effective density/Z image pairs were seen primarily in metastasis and not in normal tissue. This study indicates that by using routine clinical DECT it may be possible to monitor therapy response of bone metastases because healing or worsening bone metastases change material composition of bone. Additional studies are needed to further validate these results and to test for their correlation with outcome.

  12. Editorial: Modelling and computational challenges in granular materials

    NARCIS (Netherlands)

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


    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

  13. Computational Nanotechnology of Molecular Materials, Electronics, and Actuators with Carbon Nanotubes and Fullerenes (United States)

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


    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.


    Institute of Scientific and Technical Information of China (English)

    Jia Ruiqing; Wang Luping; Wu Xueping


    In this paper, the course of the filtration is analyzed.In order to study the filtration efficiency of the filter material, the computer program was edited.According to the results of the computer program, some important parameters of the filter material are discussed.It shows that the filtration efficiency is closely related to the diameter (d) and the size (b).In addition, by using these results and the computer program, we can analysis the relationship between the fiber structure and filter properties quantitatively.

  15. Design Considerations of Help Options in Computer-Based L2 Listening Materials Informed by Participatory Design (United States)

    Cárdenas-Claros, Mónica Stella


    This paper reports on the findings of two qualitative exploratory studies that sought to investigate design features of help options in computer-based L2 listening materials. Informed by principles of participatory design, language learners, software designers, language teachers, and a computer programmer worked collaboratively in a series of…

  16. Design Considerations of Help Options in Computer-Based L2 Listening Materials Informed by Participatory Design (United States)

    Cárdenas-Claros, Mónica Stella


    This paper reports on the findings of two qualitative exploratory studies that sought to investigate design features of help options in computer-based L2 listening materials. Informed by principles of participatory design, language learners, software designers, language teachers, and a computer programmer worked collaboratively in a series of…

  17. Material flow analysis of used personal computers in Japan. (United States)

    Yoshida, Aya; Tasaki, Tomohiro; Terazono, Atsushi


    Most personal computers (PCs) are discarded by consumers after the data files have been moved to a new PC. Therefore, a used PC collection scheme should be created that does not depend on the distribution route of new PCs. In Japan, manufacturers' voluntary take-back recycling schemes were established in 2001 (for business PCs) and 2003 (for household PCs). At the same time, the export of used PCs from Japan increased, affecting the domestic PC reuse market. These regulatory and economic conditions would have changed the flow of used PCs. In this paper, we developed a method of minimizing the errors in estimating the material flow of used PCs. The method's features include utilization of both input and output flow data and elimination of subjective estimation as much as possible. Flow rate data from existing surveys were used for estimating the flow of used PCs in Japan for fiscal years (FY) 2000, 2001, and 2004. The results show that 3.92 million and 4.88 million used PCs were discarded in FY 2000 and 2001, respectively. Approximately two-thirds of the discarded PCs were disposed of or recycled within the country, one-fourth was reused within the country, and 8% were exported. In FY 2004, 7.47 million used PCs were discarded. The ratio of domestic disposal and recycling decreased to 37% in FY 2004, whereas the domestic reuse and export ratios increased to 37% and 26%, respectively. Flows from businesses to retailers in FY 2004 increased dramatically, which led to increased domestic reuse. An increase in the flow of used PCs from lease and rental companies to secondhand shops has led to increased exports. Results of interviews with members of PC reuse companies were and trade statistics were used to verify the results of our estimation of domestic reuse and export of used PCs.

  18. Advancing a distributed multi-scale computing framework for large-scale high-throughput discovery in materials science. (United States)

    Knap, J; Spear, C E; Borodin, O; Leiter, K W


    We describe the development of a large-scale high-throughput application for discovery in materials science. Our point of departure is a computational framework for distributed multi-scale computation. We augment the original framework with a specialized module whose role is to route evaluation requests needed by the high-throughput application to a collection of available computational resources. We evaluate the feasibility and performance of the resulting high-throughput computational framework by carrying out a high-throughput study of battery solvents. Our results indicate that distributed multi-scale computing, by virtue of its adaptive nature, is particularly well-suited for building high-throughput applications.

  19. Computer technology forecast study for general aviation (United States)

    Seacord, C. L.; Vaughn, D.


    A multi-year, multi-faceted program is underway to investigate and develop potential improvements in airframes, engines, and avionics for general aviation aircraft. The objective of this study was to assemble information that will allow the government to assess the trends in computer and computer/operator interface technology that may have application to general aviation in the 1980's and beyond. The current state of the art of computer hardware is assessed, technical developments in computer hardware are predicted, and nonaviation large volume users of computer hardware are identified.


    Energy Technology Data Exchange (ETDEWEB)

    Thorne, L. F.


    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.

  1. Phenomena and computational models of non-proportional fatigue of materials

    CERN Document Server

    Skibicki, Dariusz


    This book gives an overview on the fatigue of materials under non-proportional loads. It presents the rich spectrum of phenomena and treats various computational models to mathematically describe the non-proportional fatigue of materials.

  2. X-Ray Computed Tomography for Advanced Materials and Processes. (United States)


    percent. In this example, we have assumed $I M, $5(X)K and $200K CT systems operating at 10 percent of the capital investment per year for maintenance...Computed Tomo &:aphy of Composites," WRDC-TR-90-4014, July 1990. 5. P. Burstein and R. H. Bossi, "A Guide to Computed Tomography System Specifications," WRDC...Lannutti, "Applications of High- Resolution Computed Tomography," Proceedings of the 1991 Industrial Computed Tomography II Topical Conference, May 20-24

  3. Study of Carbon Emission in Computing Scenario

    Directory of Open Access Journals (Sweden)

    Mr. Nikhil B. Dhake Mr. Pankaj M. Poul Prof. Pranav R. Shriram Prof. Kanchan V. Wankhade


    Full Text Available This paper presents a case study of what is green computing, why we need to go green computing & will tell you how to minimize the energy consumption as well how to lessen the CO2 emission by going Green Computing. The huge amount of computing manufactured worldwide has a direct impact on environment issues and scientists are conducting numerous studies in order to reduce the negative impact of computing technology on environment. Energy consumption in the datacenter reached the highs. A large corporate IT infrastructure, consumes as much as the energy produced by five power plants over the same time period. This case study will provide a rich source for anyone interested in green computing research.

  4. Computational chemistry modeling and design of photoswitchable alignment materials for optically addressable liquid crystal devices (United States)

    Marshall, K. L.; Sekera, E. R.; Xiao, K.


    Photoalignment technology based on optically switchable "command surfaces" has been receiving increasing interest for liquid crystal optics and photonics device applications. Azobenzene compounds in the form of low-molar-mass, watersoluble salts deposited either directly on the substrate surface or after dispersion in a polymer binder have been almost exclusively employed for these applications, and ongoing research in the area follows a largely empirical materials design and development approach. Recent computational chemistry advances now afford unprecedented opportunities to develop predictive capabilities that will lead to new photoswitchable alignment layer materials with low switching energies, enhanced bistability, write/erase fatigue resistance, and high laser-damage thresholds. In the work described here, computational methods based on the density functional theory and time-dependent density functional theory were employed to study the impact of molecular structure on optical switching properties in photoswitchable methacrylate and acrylamide polymers functionalized with azobenzene and spiropyran pendants.

  5. Delivery of Educational Materials in Real Time via the Computer. (United States)

    Himmelblau, D. M.


    Discusses preparation for and problems of electronic publishing applied to text modules for individual/classroom use in undergraduate chemical engineering. Also describes how the modules are authored and evaluated and how text, equations, and figures are entered into the computer for use with a wide variety of computers and terminals. (Author/JN)

  6. Ab Initio Studies of Metal Hexaboride Materials (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

  7. Studies of mesoporous inorganic materials (United States)

    Khushalani, Deepa

    Studies in synthesis and characterization of mesoporous silica have been performed. In particular, four aspects have been studied. Primarily, a new synthetic route to enlarge the porosity of mesoporous silica materials has been developed. The synthetic strategy involves aging the syntheses mixture in the mother liquor and depending on the aging time, a gradual increase in pore sizes is observed from 40 to 65 A. The growth process involves restructuring of the mesopores under mild aqueous conditions without changing the length of the alkyl chain of the surfactant or addition of auxiliary hydrocarbon molecules. The pore-enlarged products retain the crystal morphology of the starting materials and appreciable solubilization of the structure is not observed during the aging process. Templating behavior of cetylpyridinium chloride in the synthesis of mesoporous silica has also been evaluated. Noticeable improvement in the quality of the resulting product is observed through PXRD, TEM, and adsorption analyses. Synthesis of mesoporous silica is also demonstrated using templating behavior of a mixture of two surfactants: cetylpyridinium chloride (CPCl) and cetyltrimethylammonium chloride (CTACl). As the CPCl :CTACl molar ratio is decreased, a gradual increase in the d100-spacing is observed starting at ca. 41 A and in sub-angstrom increments reaching to that of ca. 43 A. A model is presented that simultaneously accounts for the higher degree of structural order of the mesoporous silica templated with CPCl and the ability to fine tune d-spacings on a sub-angstrom length scale using CPCl/CTACl mixtures. In addition, a novel non-aqueous route to formation of lamellar and hexagonal phase of mesoporous silica has been developed. Ethylene glycol is employed as a solvent and as a chelating agent. The chelate effect results in stable glycosilicate(IV) complexes which are necessary for the syntheses and the framework thermal stability of the products has been found to increase via

  8. Computational and synthetic studies with tetravinylethylenes. (United States)

    Lindeboom, Erik J; Willis, Anthony C; Paddon-Row, Michael N; Sherburn, Michael S


    Computational and experimental studies offer fresh insights into the neglected tetravinylethylene class of compounds. Both the structures and the outcomes of exploratory reactions of the parent hydrocarbon are predicted and explained in detail through high-level composite ab initio MO G4(MP2) computational studies.

  9. Computer Simulation Studies in Condensed-Matter Physics XVII (United States)

    Landau, D. P.; Lewis, S. P.; Schüttler, H.-B.

    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.

  10. 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:; Hartmann, Mateus Silveira Martins [Uninga Dental School, Passo Fundo, RS (Brazil). Postgraduate Program in Dentistry


    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)

  11. Fundamental Hyperelastic Material Study Project (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...

  12. Improving material decomposition by spectral optimization of photon counting computed tomography (United States)

    Polster, C.; Hahn, K.; Gutjahr, R.; Schöck, F.; Kappler, S.; Dietrich, O.; Flohr, T. G.


    Photon counting detectors in computed tomography facilitate measurements of spectral distributions of detected X-ray quanta in discrete energy bins. Along with the dependency on wavelength and atomic number of the mass attenuation coefficient, this information allows for reconstruction of CT images of different material bases. Decomposition of two materials is considered standard in today's dual-energy techniques. With photon-counting detectors the decomposition of more than two materials becomes achievable. Efficient detection of CT-typical X-ray spectra is a hard requirement in a clinical environment. This is fulfilled by only a few sensor materials such as CdTe or CdZnTe. In contrast to energy integrating CT-detectors, the pixel dimensions must be reduced to avoid pulse pile-up problems at clinically relevant count rates. However, reducing pixel sizes leads to increased K-escape and charge sharing effects. As a consequence, the correlation between incident and detected X-ray energy is reduced. This degradation is quantified by the detector response function. The goal of this study is to improve the achievable material decomposition by adapting the incident X-ray spectrum with respect to the properties (i.e. the detector response function) of a photon counting detector. A significant improvement of a material decomposition equivalent metric is achievable when using specific materials as X-ray pre-filtration (K-edge filtering) while maintaining the applied patient dose and image quality.

  13. Examining the effects of computational tools on students' understanding of thermodynamics of material concepts and representations (United States)

    Ogunwuyi, Oluwatosin

    Technology is becoming a more critical agent for supporting learning as well as research in science and engineering. In particular, technology-based tools in the form of simulations and virtual environments support learning using mathematical models and computational methods. The purpose of this research is to: (a) measure the value added in conveying Thermodynamics of materials concepts with a blended learning environment using computational simulation tools with lectures; and (b) characterize students' use of representational forms to convey their conceptual understanding of core concepts within a learning environment that blended Gibbs computational resource and traditional lectures. A mix-method approach was implemented that included the use of statistical analysis to compare student test performance as a result of interacting with Gibbs tool and the use of Grounded Theory inductive analysis to explore students' use of representational forms to express their understanding of thermodynamics of material concepts. Results for the quantitative study revealed positive gains in students' conceptual understanding before and after interacting with Gibbs tool for the majority of the concepts tested. In addition, insight gained from the qualitative analysis helped provide understanding about how students utilized representational forms in communicating their understanding of thermodynamics of material concepts. Knowledge of how novice students construct meaning in this context will provide insight for engineering education instructors and researchers in understanding students' learning processes in the context of educational environments that integrate expert simulation tools as part of their instructional resources for foundational domain knowledge.

  14. Nanoscale energy transport and harvesting a computational study

    CERN Document Server

    Gang, Zhang


    Molecular Dynamics Simulations for Computing Thermal Conductivity of Nano MaterialsNonequilibrium Phonon Green's Function Simulation and Its Application to Carbon NanotubesThermal Conduction of GrapheneBallistic Thermal Transport by Phonons at Low Temperatures in Low-Dimensional Quantum StructuresSurface functionalization induced thermal conductivity attenuation in silicon nanowires: A molecular dynamics study

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

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang


    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....

  16. 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)


    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.

  17. Computational Center for Studies of Plasma Microturbulence

    Energy Technology Data Exchange (ETDEWEB)

    William Dorland


    The Maryland Computational Center for Studies of Microturbulence (CCSM) was one component of a larger, multi-institutional Plasma Microturbulence Project, funded through what eventually became DOE's Scientific Discovery Through Advanced Computing Program. The primary focus of research in CCSM was to develop, deploy, maintain, and utilize kinetic simulation techniques, especially the gyrokinetic code called GS2.

  18. A Codesign Case Study in Computer Graphics

    DEFF Research Database (Denmark)

    Brage, Jens P.; Madsen, Jan


    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...

  19. Evaluation of Three-Dimensional Printed Materials for Simulation by Computed Tomography and Ultrasound Imaging. (United States)

    Mooney, James J; Sarwani, Nabeel; Coleman, Melissa L; Fotos, Joseph S


    The use of three-dimensional (3D) printing allows for creation of custom models for clinical care, education, and simulation. Medical imaging, given the significant role it plays in both clinical diagnostics and procedures, remains an important area for such education and simulation. Unfortunately, the materials appropriate for use in simulation involving radiographic or ultrasound imaging remains poorly understood. Therefore, our study was intended to explore the characteristics of readily available 3D printing materials when visualized by computed tomography (CT) and ultrasound. Seven 3D printing materials were examined in standard shapes (cube, cylinder, triangular prism) with a selection of printing methods ("open," "whole," and "solid" forms). For CT imaging, these objects were suspended in a gelatin matrix molded to match a standard human CT phantom. For ultrasound imaging, the objects were placed in acrylic forms filled with a gelatin matrix. All images were examined using OsiriX software. Computed tomography imaging revealed marked variation in materials' Hounsfield units as well as patterning and artifact. The Hounsfield unit variations revealed a number of materials suitable for simulation various human tissues. Ultrasound imaging showed echogenicity in all materials, with some variability in shadowing and posterior wall visualization. We were able to demonstrate the potential utility for 3D printing in the creation of CT and ultrasound simulation models. The similar appearance of materials via ultrasound supports their broad utility for select tissue types, whereas the more variable appearance via CT suggests greater potential for simulating differing tissues but requiring multiple printer technologies to do so.

  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 (United States)


    material chemistry structure are studied following a molecular dynamics (MD) computational modeling methodology. Calcium ions are replaced with... chemistry structure. Conference Name: 1st Pan-American Conference on Computational Mechanics Conference Date: April 27, 2015 1st Pan-American Congress on...MODELING OF C-S-H Material chemistry level modeling following the principles and techniques commonly grouped under Computational Material Science is

  1. A community-based study of asthenopia in computer operators

    Directory of Open Access Journals (Sweden)

    Bhanderi Dinesh


    Full Text Available Context: There is growing body of evidence that use of computers can adversely affect the visual health. Considering the rising number of computer users in India, computer-related asthenopia might take an epidemic form. In view of that, this study was undertaken to find out the magnitude of asthenopia in computer operators and its relationship with various personal and workplace factors. Aims: To study the prevalence of asthenopia among computer operators and its association with various epidemiological factors. Settings and Design: Community-based cross-sectional study of 419 subjects who work on computer for varying period of time. Materials and Methods: Four hundred forty computer operators working in different institutes were selected randomly. Twenty-one did not participate in the study, making the nonresponse rate 4.8%. Rest of the subjects (n = 419 were asked to fill a pre-tested questionnaire, after obtaining their verbal consent. Other relevant information was obtained by personal interview and inspection of workstation. Statistical Analysis Used: Simple proportions and Chi-square test. Results: Among the 419 subjects studied, 194 (46.3% suffered from asthenopia during or after work on computer. Marginally higher proportion of asthenopia was noted in females compared to males. Occurrence of asthenopia was significantly associated with age of starting use of computer, presence of refractive error, viewing distance, level of top of the computer screen with respect to eyes, use of antiglare screen and adjustment of contrast and brightness of monitor screen. Conclusions: Prevalence of asthenopia was noted to be quite high among computer operators, particularly in those who started its use at an early age. Individual as well as work-related factors were found to be predictive of asthenopia.

  2. Computer simulation of ion beam analysis of laterally inhomogeneous materials

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, M.


    The program STRUCTNRA for the simulation of ion beam analysis charged particle spectra from arbitrary two-dimensional distributions of materials is described. The code is validated by comparison to experimental backscattering data from a silicon grating on tantalum at different orientations and incident angles. Simulated spectra for several types of rough thin layers and a chessboard-like arrangement of materials as example for a multi-phase agglomerate material are presented. Ambiguities between back-scattering spectra from two-dimensional and one-dimensional sample structures are discussed.

  3. Polymer Physics Prize: Designing ''Materials that Compute'': Exploiting the Properties of Self-oscillating Polymer Gels (United States)

    Balazs, Anna

    Lightweight, deformable materials that can sense and respond to human touch and motion can be the basis of future wearable computers, where the material itself will be capable of performing computations. To facilitate the creation of ''materials that compute'', we draw from two emerging modalities for computation: chemical computing, which relies on reaction-diffusion mechanisms to perform operations, and oscillatory computing, which performs pattern recognition through synchronization of coupled oscillators. Chemical computing systems, however, suffer from the fact that the reacting species are coupled only locally; the coupling is limited by diffusion as the chemical waves propagate throughout the system. Additionally, oscillatory computing systems have not utilized a potentially wearable material. To address both these limitations, we develop the first model for coupling self-oscillating polymer gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The resulting transduction between chemo-mechanical and electrical energy creates signals that can be propagated quickly over long distances and thus, permits remote, non-diffusively coupled oscillators to communicate and synchronize. The oscillators can be organized into arbitrary topologies because the electrical connections lift the limitations of diffusive coupling. Using our model, we predict the synchronization behavior that can be used for computational tasks, ultimately enabling ''materials that compute''.

  4. Error Mitigation in Computational Design of Sustainable Energy Materials

    DEFF Research Database (Denmark)

    Christensen, Rune

    functional theory calculations contribute in research and development of these technologies. Systematic errors are present in calculations with general gradient approximation functionals for all three technologies. Such functionals will in many cases be the best compromise of computational cost and accuracy...... networks. The method can validate the use of a neural network for emulation of density functional theory calculations for given atomic configuration....... 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...


    Hanna, T. L.


    The basic function of a manufacturer's production support engineering unit is to identify, document, and dispose of hardware that does not conform to drawing requirements. CAMRAD, a program designed for rapid input and retrieval of all data used in engineering-to-manufacturing support operations, aids the engineer by automating the material review disposition process. Before CAMRAD, material review record searches were manual. The time spent searching through old documents precluded the timely disposition of new material reviews. CAMRAD facilitates the research of material review histories and provides for the efficient processing of material review documents. Three SmartWare project files control the operation of CAMRAD. The project file CAMRAD initializes variables for the other project files and specifies the pathing of the CAMRAD program, database files, and document files. The project file DATARAD controls all data management functions. The database consists of individual files containing all records of specific hardware discrepancies for a given part number. There are four basic avenues for records searches: part serial number, feature, Material Review (MR) number, and non-conformance. WORDRAD is the project file which controls the management of document files created when processing a material review disposition. Given a material review report identifying a defective hardware item, the production support engineer can use CAMRAD to quickly search the database for any history of the same problem, find out how well the problem has been documented, and create appropriate documentation for this latest occurrence. CAMRAD is written in the Smart Programming Language and is designed to run on IBM PC compatibles with the SmartWare v. 3.1 software package available from Informix Software. CAMRAD was developed in 1987. SmartWare is a registered trademark of Informix Software, Inc. IBM PC is a registered trademark of International Business Machines Corporation.

  6. Visualization of self-healing materials by X-ray computed micro-tomography at UGCT


    Bultreys, Tom; Masschaele, Bert; Hillewaere, Xander; Dierick, Manuel; Van Loo, Denis; Van Hoorebeke, Luc; Cnudde, Veerle


    This work presents recent advancements in X-ray micro-computed tomography (XRMCT) of self-healing materials at Ghent University’s Centre for X-ray Tomography (UGCT). Results of XRMCT imaging in a self-healing polymer system are shown to demonstrate the use of XRMCT in self-healing studies. Furthermore, two new XRMCT scanners are presented. The HECTOR scanner was designed for large samples and strongly attenuating samples, and is therefore well suited to study self-healing concrete. The EMCT s...

  7. 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...

  8. Study on global cloud computing research trend (United States)

    Ma, Feicheng; Zhan, Nan


    Since "cloud computing" was put forward by Google , it quickly became the most popular concept in IT industry and widely permeated into various areas promoted by IBM, Microsoft and other IT industry giants. In this paper the methods of bibliometric analysis were used to investigate the global cloud computing research trend based on Web of Science (WoS) database and the Engineering Index (EI) Compendex database. In this study, the publication, countries, institutes, keywords of the papers was deeply studied in methods of quantitative analysis, figures and tables are used to describe the production and the development trends of cloud computing.

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

    Vekli, Gülsah Sezen; Çimer, Atilla


    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…

  10. Hybrid hierarchical bio-based materials: Development and characterization through experimentation and computational simulations (United States)

    Haq, Mahmoodul

    Environmentally friendly bio-based composites with improved properties can be obtained by harnessing the synergy offered by hybrid constituents such as multiscale (nano- and micro-scale) reinforcement in bio-based resins composed of blends of synthetic and natural resins. Bio-based composites have recently gained much attention due to their low cost, environmental appeal and their potential to compete with synthetic composites. The advantage of multiscale reinforcement is that it offers synergy at various length scales, and when combined with bio-based resins provide stiffness-toughness balance, improved thermal and barrier properties, and increased environmental appeal to the resulting composites. Moreover, these hybrid materials are tailorable in performance and in environmental impact. While the use of different concepts of multiscale reinforcement has been studied for synthetic composites, the study of mukiphase/multiscale reinforcements for developing new types of sustainable materials is limited. The research summarized in this dissertation focused on development of multiscale reinforced bio-based composites and the effort to understand and exploit the synergy of its constituents through experimental characterization and computational simulations. Bio-based composites consisting of petroleum-based resin (unsaturated polyester), natural or bio-resin (epoxidized soybean and linseed oils), natural fibers (industrial hemp), and nanosilicate (nanoclay) inclusions were developed. The work followed the "materials by Mahmoodul Haq design" philosophy by incorporating an integrated experimental and computational approach to strategically explore the design possibilities and limits. Experiments demonstrated that the drawbacks of bio-resin addition, which lowers stiffness, strength and increases permeability, can be counter-balanced through nanoclay reinforcement. Bio-resin addition yields benefits in impact strength and ductility. Conversely, nanoclay enhances stiffness

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

    DEFF Research Database (Denmark)

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

    . 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...... numerical method provides a framework for quantifying a wide range of subglacial sediment-water processes, which are a key unknown in our ability to model the future evolution of ice sheets....

  12. Computation of electronic structure and magnetic properties of strongly correlated materials with LDA+DMFT method (United States)

    Skornyakov, S. L.; Anisimov, V. I.


    In this review, we describe general ideas of the LDA+DMFT method which merges dynamical mean-field theory (DMFT) and density functional theory (in particular the local density approximation (LDA)). Nowadays, the LDA+DMFT computational scheme is the most powerful numerical tool for studying physical properties of real materials and chemical compounds. It incorporates the advantage of DMFT to treat the full range of local dynamical Coulomb correlations and the ability of band methods to describe material-specific band dispersion caused by the lattice periodicity. We briefly discuss underlying physical ideas of LDA+DMFT and its mathematical implementation. Then different algorithms applied to solution of the DMFT impurity problem are briefly described. We then give examples of successful applications of the LDA+DMFT method to study spectral and magnetic properties of recently synthesized compounds like pnictide superconductors as well as classic charge-transfer systems NiO and MnO.

  13. Appraisal of soft computing techniques in prediction of total bed material load in tropical rivers

    Indian Academy of Sciences (India)

    C K Chang; H Md Azamathulla; N A Zakaria; A Ab Ghani


    This paper evaluates the performance of three soft computing techniques, namely Gene-Expression Programming (GEP) (Zakaria et al 2010), Feed Forward Neural Networks (FFNN) (Ab Ghani et al 2011), and Adaptive Neuro-Fuzzy Inference System (ANFIS) in the prediction of total bed material load for three Malaysian rivers namely Kurau, Langat and Muda. The results of present study are very promising: FFNN (2 = 0.958, RMSE = 0.0698), ANFIS (2 = 0.648, RMSE = 6.654), and GEP (2 = 0.97, RMSE = 0.057), which support the use of these intelligent techniques in the prediction of sediment loads in tropical rivers.

  14. Charge transport in carbon nanotubes based materials: a Kubo-Greenwood computational approach (United States)

    Ishii, Hiroyuki; Triozon, François; Kobayashi, Nobuhiko; Hirose, Kenji; Roche, Stephan


    In this contribution, we present a numerical study of quantum transport in carbon nanotubes based materials. After a brief presentation of the computational approach used to investigate the transport coefficient (Kubo method), the scaling properties of quantum conductance in ballistic regime as well as in the diffusive regimes are illustrated. The impact of elastic (impurities) and dynamical disorders (phonon vibrations) are analyzed separately, with the extraction of main transport length scales (mean free path and localization length), as well as the temperature dependence of the nanotube resistance. The results are found in very good agreement with both analytical results and experimental data, demonstrating the predictability efficiency of our computational strategy. To cite this article: H. Ishii et al., C. R. Physique 10 (2009).

  15. 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 chapter......, each of them with one type of pollution source.......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...

  16. 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...... has been applied to guide the search for new materials. The main descriptors of the properties relevant for the screening are: heat of formation, electronic bandgap, and positions of the band edges with respect to the red-ox levels of water. A recently implemented exchange-correlation functional...... for visible light harvesting, 20 for the one-photon and 12 for the two-photon water splitting process. In addition, 16 candidates were suggested for the transparent shielding of the photocatalyst. The problem of corrosion has been addressed for the candidates for the one-photon scheme using Pourbaix diagrams...

  17. A superconductor material model for hysteresis losses computation

    Energy Technology Data Exchange (ETDEWEB)

    Satiramatekul, Thitipong [Faculty of Engineering at Kamphaengsaen, Kasetsart University, Nakhon Pathom 73140 (Thailand); Bouillault, Frederic [Electrical Engineering Laboratory of Paris, Plateau de Moulon, Gif-sur-Yvette Cedex 91192 (France)


    The aim of this work was to calculate the hysteresis losses in the superconductor materials. For that, we used one macroscopic model which obtained by altering Bean's model. We propose the finite element method for the numerical modeling. Our problem consists of an infinitely long superconducting line plunged in a uniform field varying periodically in time. In this paper, we present the influence of the shape and the amplitude of the applied magnetic field to the instantaneous losses. We also present two various methods for calculating the average losses. Moreover, we could in particular obtain the quantities such as the current density or the magnetization in order to know the phenomenon of superconductivity in superconductor materials. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)



    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.

  19. Model of Integration of Material Flow Control System with MES/ERP System via Cloud Computing

    National Research Council Canada - National Science Library

    Peter Peniak


    This article deals with a model of application gateway for integration of Material Flow Control System with ERP/MES systems, which are provided by Cloud Computing and Software as Service delivery model...

  20. Study on Hydrogen Storage Materials (United States)

    Sugiyama, Jun


    Complex hydrides have been heavily investigated as a hydrogen storage material, particularly for future vehicular applications. The present major problem of such complex hydrides is their relatively high hydrogen desorption temperature (Td). In order to find a predominant parameter for determining Td, we have investigated internal nuclear magnetic fields in several complex hydrides, such as, lithium and sodium alanates, borohydrides, and magnesium hydrides, with a muon spin rotation and relaxation (μ+SR) technique. At low temperatures, the μ+SR spectrum obtained in a zero external field (ZF) exhibits a clear oscillation due to the formation of a three spin 1/2 system, HμH, besides Mg(BH4)2 and Sc(BH4)2. Such oscillatory signal becomes weaker and weaker with increasing temperature, and finally disappears above around room temperature. However, the volume fraction of the HμH signal to the whole asymmetry at 5 K is found to be a good indicator for Td in borohydrides. At high temperatures, on the contrary, the ZF-spectrum for MgH2 shows a Kubo-Toyabe like relaxation due to a random nuclear magnetic field of 1H. Such nuclear magnetic field becomes dynamic well below Td in the milled MgH2, indicating a significant role on H-diffusion in solids for determining Td.

  1. US QCD computational performance studies with PERI (United States)

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


    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.

  2. US QCD computational performance studies with PERI

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y [Renaissance Computing Institute, Chapel Hill NC (United States); Fowler, R [Renaissance Computing Institute, Chapel Hill NC (United States); Huck, K [University of Oregon, Eugene OR (United States); Malony, A [University of Oregon, Eugene OR (United States); Porterfield, A [Renaissance Computing Institute, Chapel Hill NC (United States); Reed, D [Renaissance Computing Institute, Chapel Hill NC (United States); Shende, S [University of Oregon, Eugene OR (United States); Taylor, V [Texas A and M University, College Station TX (United States); Wu, X [Texas A and M University, College Station TX (United States)


    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.

  3. 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


    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...

  4. Neutron Scattering Studies of Nanomagnetism and Artificially Structured Materials

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimmons, M.R.; Bader, S.D.; Borchers, J.A.; Felcher, G.P.; Furdyna, J.K.; Hoffmann, A.; Kortright, J.B.; Schuller, Ivan K.; Schulthess, T.C.; Sinha, S.K.; Toney, M.F.; Weller, D.; Wolf, S.


    Nanostructured magnetic materials are intensively studied due to their unusual properties and promise for possible applications. The key issues in these materials relate to the connection between their physical properties (transport, magnetism, mechanical, etc.) and their chemical-physical structure. In principle, a detailed knowledge of the chemical and physical structure allows calculation of their physical properties. Theoretical and computational methods are rapidly evolving so that magnetic properties of nanostructured materials might soon be predicted. Success in this endeavor requires detailed quantitative understanding of the magnetic structure and properties.

  5. Computational analysis of azine-N-oxides as energetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Ritchie, J.P.


    A BKW equation of state in a 1-dimensional hydrodynamic simulation of the cylinder test can be used to estimate the performance of explosives. Using this approach, the novel explosive 1,4-diamino-2,3,5,6-tetrazine-2,5-dioxide (TZX) was analyzed. Despite a high detonation velocity and a predicted CJ pressure comparable to that of RDX, TZX performs relatively poorly in the cylinder test. Theoretical and computational analysis shows this to be the result of a low heat of detonation. A conceptual strategy is proposed to remedy this problem. In order to predict the required heats of formation, new ab initio group equivalents were developed. Crystal structure calculations are also described that show hydrogen-bonding is important in determining the density of TZX and related compounds.

  6. 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 (Italy)


    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.

  7. Computer methods for ITER-like materials LIBS diagnostics (United States)

    Łepek, Michał; Gąsior, Paweł


    Recent development of Laser-Induced Breakdown Spectroscopy (LIBS) caused that this method is considered as the most promising for future diagnostic applications for characterization of the deposited materials in the International Thermonuclear Experimental Reactor (ITER), which is currently under construction. In this article the basics of LIBS are shortly discussed and the software for spectra analyzing is presented. The main software function is to analyze measured spectra with respect to the certain element lines presence. Some program operation results are presented. Correct results for graphite and aluminum are obtained although identification of tungsten lines is a problem. The reason for this is low tungsten lines intensity, and thus low signal to noise ratio of the measured signal. In the second part artificial neural networks (ANNs) as the next step for LIBS spectra analyzing are proposed. The idea is focused on multilayer perceptron network (MLP) with backpropagation learning method. The potential of ANNs for data processing was proved through application in several LIBS-related domains, e.g. differentiating ancient Greek ceramics (discussed). The idea is to apply an ANN for determination of W, Al, C presence on ITER-like plasma-facing materials.

  8. Computer Simulation Study of Bipolaron Formation

    NARCIS (Netherlands)

    Raedt, H. De; Lagendijk, A.


    Monte Carlo computer simulation techniques are used to study the formation of bipolarons on a lattice. The transition between the three possible states, extended, two-polaron, and bipolaron is studied. The phase diagram as a function of the strengths of the electron-phonon coupling and repulsive int

  9. Computer Networks and African Studies Centers. (United States)

    Kuntz, Patricia S.

    The use of electronic communication in the 12 Title VI African Studies Centers is discussed, and the networks available for their use are reviewed. It is argued that the African Studies Centers should be on the cutting edge of contemporary electronic communication and that computer networks should be a fundamental aspect of their programs. An…

  10. Central Issues in the Use of Computer-Based Materials for High Volume Entrepreneurship Education (United States)

    Cooper, Billy


    This article discusses issues relating to the use of computer-based learning (CBL) materials for entrepreneurship education at university level. It considers CBL as a means of addressing the increased volume and range of provision required in the current context. The issues raised in this article have importance for all forms of computer-based…

  11. Computational techniques in tribology and material science at the atomic level (United States)

    Ferrante, J.; Bozzolo, G. H.


    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.

  12. Computer Ethics: New Study Area for Engineering Science Students (United States)

    Johnson, Deborah G.


    Computer professionals are beginning to look toward codes of ethics and legislation to control the use of software. A project has been established at Rensselaer Polytechnic Institute to develop teaching materials on computer ethics. (BB)

  13. 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)


    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

  14. A Computing Infrastructure for Supporting Climate Studies (United States)

    Yang, C.; Bambacus, M.; Freeman, S. M.; Huang, Q.; Li, J.; Sun, M.; Xu, C.; Wojcik, G. S.; Cahalan, R. F.; NASA Climate @ Home Project Team


    Climate change is one of the major challenges facing us on the Earth planet in the 21st century. Scientists build many models to simulate the past and predict the climate change for the next decades or century. Most of the models are at a low resolution with some targeting high resolution in linkage to practical climate change preparedness. To calibrate and validate the models, millions of model runs are needed to find the best simulation and configuration. This paper introduces the NASA effort on Climate@Home project to build a supercomputer based-on advanced computing technologies, such as cloud computing, grid computing, and others. Climate@Home computing infrastructure includes several aspects: 1) a cloud computing platform is utilized to manage the potential spike access to the centralized components, such as grid computing server for dispatching and collecting models runs results; 2) a grid computing engine is developed based on MapReduce to dispatch models, model configuration, and collect simulation results and contributing statistics; 3) a portal serves as the entry point for the project to provide the management, sharing, and data exploration for end users; 4) scientists can access customized tools to configure model runs and visualize model results; 5) the public can access twitter and facebook to get the latest about the project. This paper will introduce the latest progress of the project and demonstrate the operational system during the AGU fall meeting. It will also discuss how this technology can become a trailblazer for other climate studies and relevant sciences. It will share how the challenges in computation and software integration were solved.


    Directory of Open Access Journals (Sweden)

    Renata Lis


    Full Text Available In the days of the visual culture a manner of the transmission of information plays a very important role. Adopting a technique of the join of text, graphics, sound and animation in frames of the uniform structure of presenting data, particularly in the education, it is possible to achieve good results in handing over of knowledge than at using only one of the media. The article presents the results of research devoted to the influence of visual and textual teaching materials, on the level of assimilation of knowledge subjects and their involvement in the assimilation of content. The analysis of the results showed that the visualization of teaching content is a factor significantly activating the educational process and affecting the level of knowledge assimilation.

  16. Basis Function Sampling: A New Paradigm for Material Property Computation (United States)

    Whitmer, Jonathan K.; Chiu, Chi-cheng; Joshi, Abhijeet A.; de Pablo, Juan J.


    Wang-Landau sampling, and the associated class of flat histogram simulation methods have been remarkably helpful for calculations of the free energy in a wide variety of physical systems. Practically, convergence of these calculations to a target free energy surface is hampered by reliance on parameters which are unknown a priori. Here, we derive and implement a method built upon orthogonal functions which is fast, parameter-free, and (importantly) geometrically robust. The method is shown to be highly effective in achieving convergence. An important feature of this method is its ability to attain arbitrary levels of description for the free energy. It is thus ideally suited to in silico measurement of elastic moduli and other material properties related to free energy perturbations. We demonstrate the utility of such applications by applying our method to calculate the Frank elastic constants of the Lebwohl-Lasher model of liquid crystals.

  17. Computational Design of New Materials for Ammonia Storage

    DEFF Research Database (Denmark)

    Jensen, Peter Bjerre; Quaade, Ulrich

    by using the available operators,which are based on a combination of chemical knowledge and random events.The initial experimental tests of the identified candidates showed promisingresults, but did also reveal that the materials can be challenging to synthesize,and might degrade during ammonia desorption......Many renewable energy technologies are currently being developed, but most have the major drawback, that the energy is not generated when needed, and storage of the energy is therefore essential. For transportation applications,an energy carrier offering a high energy density is needed. Ammonia...... is one possible energy carrier offering high gravimetric and volumetric capacities. A major drawback regarding ammonia is however its toxicity requiring careful handling and storage.Instead of handling the ammonia directly, it is possible to store it safely and completely reversibly in many different...


    Energy Technology Data Exchange (ETDEWEB)

    Sabau, Adrian S [ORNL


    To accelerate the introduction of new cast alloys, the simultaneous modeling and simulation of multiphysical phenomena needs to be considered in the design and optimization of mechanical properties of cast components. The required models related to casting defects, such as microporosity and hot tears, are reviewed. Three aluminum alloys are considered A356, 356 and 319. The data on calculated solidification shrinkage is presented and its effects on microporosity levels discussed. Examples are given for predicting microporosity defects and microstructure distribution for a plate casting. Models to predict fatigue life and yield stress are briefly highlighted here for the sake of completion and to illustrate how the length scales of the microstructure features as well as porosity defects are taken into account for modeling the mechanical properties. Thus, the data on casting defects, including microstructure features, is crucial for evaluating the final performance-related properties of the component. ACKNOWLEDGEMENTS This work was performed under a Cooperative Research and Development Agreement (CRADA) with the Nemak Inc., and Chrysler Co. for the project "High Performance Cast Aluminum Alloys for Next Generation Passenger Vehicle Engines. The author would also like to thank Amit Shyam for reviewing the paper and Andres Rodriguez of Nemak Inc. Research sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, as part of the Propulsion Materials Program under contract DE-AC05-00OR22725 with UT-Battelle, LLC. Part of this research was conducted through the Oak Ridge National Laboratory's High Temperature Materials Laboratory User Program, which is sponsored by the U. S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program.

  19. Methods for Computing Accurate Atomic Spin Moments for Collinear and Noncollinear Magnetism in Periodic and Nonperiodic Materials. (United States)

    Manz, Thomas A; Sholl, David S


    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.

  20. Quantitative material decomposition using spectral computed tomography with an energy-resolved photon-counting detector. (United States)

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


    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

  1. Self-Regulation and Performance in Problem-Solving Using Physical Materials or Computers in Children with Intellectual Disability (United States)

    Nader-Grosbois, Nathalie; Lefevre, Nathalie


    This study compares self-regulation in 29 children with intellectual disability and 30 typically developing children, who solved tasks using physical materials or computers. Their cognitive, linguistic levels were assessed in order to match the children of both groups. In the presence of their mothers and fathers, the children were asked to…

  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


    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. Studies of molecular properties of polymeric materials (United States)

    Harries, W. L.; Long, Sheila Ann T.; Long, Edward R., Jr.


    Aerospace environment effects (high energy electrons, thermal cycling, atomic oxygen, and aircraft fluids) on polymeric and composite materials considered for structural use in spacecraft and advanced aircraft are examined. These materials include Mylar, Ultem, and Kapton. In addition to providing information on the behavior of the materials, attempts are made to relate the measurements to the molecular processes occurring in the material. A summary and overview of the technical aspects are given along with a list of the papers that resulted from the studies. The actual papers are included in the appendices and a glossary of technical terms and definitions is included in the front matter.

  4. Evaluation of metal artefact reduction in cone-beam computed tomography images of different dental materials. (United States)

    Queiroz, Polyane Mazucatto; Oliveira, Matheus Lima; Groppo, Francisco Carlos; Haiter-Neto, Francisco; Freitas, Deborah Queiroz


    The aim of this study is to evaluate the efficacy of metal artefact reduction (MAR) in different dental materials with Picasso Trio cone-beam computed tomography (CBCT) scanner. Three imaging phantoms were custom-made of acrylic resin. Each phantom presented three cylinders of the same material: dental amalgam alloy, gutta-percha or aluminium-copper alloy. CBCT scans were performed on Picasso Trio unit with and without MAR, and artefact expression (standard deviation of grey values) was obtained and compared by Kruskal-Wallis and Student-Newman-Keuls (post hoc) (α = 0.05). Significant reduction of artefact expression (p  0.05) was observed with or without MAR when gutta-percha was scanned. MAR was effective in reducing artefacts arising from dental alloys on CBCT images. Dental materials of high atomic number and density are widely used in dentistry and can produce artefact that compromise CBCT image. The present study demonstrated that metal artefact reduction algorithm is an effective tool to improve image quality.

  5. High-Throughput Computational Design of Advanced Functional Materials: Topological Insulators and Two-Dimensional Electron Gas Systems (United States)

    Yang, Kesong

    As a rapidly growing area of materials science, high-throughput (HT) computational materials design is playing a crucial role in accelerating the discovery and development of novel functional materials. In this presentation, I will first introduce the strategy of HT computational materials design, and take the HT discovery of topological insulators (TIs) as a practical example to show the usage of such an approach. Topological insulators are one of the most studied classes of novel materials because of their great potential for applications ranging from spintronics to quantum computers. Here I will show that, by defining a reliable and accessible descriptor, which represents the topological robustness or feasibility of the candidate, and by searching the quantum materials repository, we have automatically discovered 28 TIs (some of them already known) in five different symmetry families. Next, I will talk about our recent research work on the HT computational design of the perovskite-based two-dimensional electron gas (2DEG) systems. The 2DEG formed on the perovskite oxide heterostructure (HS) has potential applications in next-generation nanoelectronic devices. In order to achieve practical implementation of the 2DEG in the device design, desired physical properties such as high charge carrier density and mobility are necessary. Here I show that, using the same strategy with the HT discovery of TIs, by introducing a series of combinatorial descriptors, we have successfully identified a series of candidate 2DEG systems based on the perovskite oxides. This work provides another exemplar of applying HT computational design approach for the discovery of advanced functional materials.

  6. Damage Mechanics of Composite Materials: Constitutive Modeling and Computational Algorithms (United States)


    la Rupture par Endommagement", J. de Mech. Applique, Vol. 2, pp. 317-365. 23. LEMAITRE, J. AND J. L. CHABOCHE, (1985), Mechanique des Materiaux ...microcracks. Batchelor (1970), Batchelor and Green (1972), and Hinch (1977) applied this approach to the study of fluid suspensions within the framework of...3-D Statistical Micromechanical Theory 78 111.7. References 1. BATCHELOR, G. K., (1970), "The stress system in a suspension of force-free particles

  7. 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)


    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

  8. First-principles computation of mantle materials in crystalline and amorphous phases (United States)

    Karki, Bijaya B.


    magnitudes with pressure, temperature, and composition. The predicted high compressibility and complex dynamical behavior can be associated with structural changes (involving non-bridging oxygen, oxygen tri-clusters, Si-O pentahedra, etc.) occurring on compression. We envision future prospect for massively parallel/distributed computing of unprecedented magnitude and scope in the study of relevant materials for Earth, super-Earth, and other planets. A renewed computational theme perhaps should be the first-principles simulations of large systems (with long runs) that are necessary to explore realistic (natural) compositions, polycrystalline phases, multi-component melts, crystal/melt interfaces, trace element partitioning, etc.

  9. Experiments with a low-cost system for computer graphics material model acquisition (United States)

    Rushmeier, Holly; Lockerman, Yitzhak; Cartwright, Luke; Pitera, David


    We consider the design of an inexpensive system for acquiring material models for computer graphics rendering applications in animation, games and conceptual design. To be useful in these applications a system must be able to model a rich range of appearances in a computationally tractable form. The range of appearance of interest in computer graphics includes materials that have spatially varying properties, directionality, small-scale geometric structure, and subsurface scattering. To be computationally tractable, material models for graphics must be compact, editable, and efficient to numerically evaluate for ray tracing importance sampling. To construct appropriate models for a range of interesting materials, we take the approach of separating out directly and indirectly scattered light using high spatial frequency patterns introduced by Nayar et al. in 2006. To acquire the data at low cost, we use a set of Raspberry Pi computers and cameras clamped to miniature projectors. We explore techniques to separate out surface and subsurface indirect lighting. This separation would allow the fitting of simple, and so tractable, analytical models to features of the appearance model. The goal of the system is to provide models for physically accurate renderings that are visually equivalent to viewing the original physical materials.

  10. 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


    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.

  11. Continuum Mechanical and Computational Aspects of Material Behavior

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  12. Optimization Design Model of Functional Gradient Thermal Barrier Coating Material by Using Parallel Computation

    Directory of Open Access Journals (Sweden)

    Chen Zhao


    Full Text Available It is important for huge ship to find the ceramic/metal functional gradient thermal barrier coating materials. A parallel computation model is built for optimization design of three-dimensional ceramic/metal functionally gradient thermal barrier coating material. According to the control equation and initial-boundary conditions, the heat transfer problem is considered, and numerical algorithms of optimization design is constructed by adapting difference method. The numerical results shows that gradient thermal barrier coating material can improve the function of material.

  13. The Impact and Promise of Open-Source Computational Material for Physics Teaching (United States)

    Christian, Wolfgang


    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.

  14. Reducing Vehicle Weight and Improving U.S. Energy Efficiency Using Integrated Computational Materials Engineering (United States)

    Joost, William J.


    Transportation accounts for approximately 28% of U.S. energy consumption with the majority of transportation energy derived from petroleum sources. Many technologies such as vehicle electrification, advanced combustion, and advanced fuels can reduce transportation energy consumption by improving the efficiency of cars and trucks. Lightweight materials are another important technology that can improve passenger vehicle fuel efficiency by 6-8% for each 10% reduction in weight while also making electric and alternative vehicles more competitive. Despite the opportunities for improved efficiency, widespread deployment of lightweight materials for automotive structures is hampered by technology gaps most often associated with performance, manufacturability, and cost. In this report, the impact of reduced vehicle weight on energy efficiency is discussed with a particular emphasis on quantitative relationships determined by several researchers. The most promising lightweight materials systems are described along with a brief review of the most significant technical barriers to their implementation. For each material system, the development of accurate material models is critical to support simulation-intensive processing and structural design for vehicles; improved models also contribute to an integrated computational materials engineering (ICME) approach for addressing technical barriers and accelerating deployment. The value of computational techniques is described by considering recent ICME and computational materials science success stories with an emphasis on applying problem-specific methods.

  15. Insights from the 3rd World Congress on Integrated Computational Materials Engineering (United States)

    Howe, D.; Goodlet, B.; Weaver, J.; Spanos, G.


    The 3rd World Congress on Integrated Computational Materials Engineering (ICME) was a forum for presenting the "state-of-the-art" in the ICME discipline, as well as for charting a path for future community efforts. The event concluded with in an interactive panel-led discussion that addressed such topics as integrating efforts between experimental and computational scientists, uncertainty quantification, and identifying the greatest challenges for future workforce preparation. This article is a summary of this discussion and the thoughts presented.

  16. FOREWORD: Some thoughts about Jürgen Hafner's work in computational materials science Some thoughts about Jürgen Hafner's work in computational materials science (United States)

    Heine, Volker


    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

  17. A computational study of carbon dioxide adsorption on solid boron. (United States)

    Sun, Qiao; Wang, Meng; Li, Zhen; Du, Aijun; Searles, Debra J


    Capturing and sequestering carbon dioxide (CO2) can provide a route to partial mitigation of climate change associated with anthropogenic CO2 emissions. Here we report a comprehensive theoretical study of CO2 adsorption on two phases of boron, α-B12 and γ-B28. The theoretical results demonstrate that the electron deficient boron materials, such as α-B12 and γ-B28, can bond strongly with CO2 due to Lewis acid-base interactions because the electron density is higher on their surfaces. In order to evaluate the capacity of these boron materials for CO2 capture, we also performed calculations with various degrees of CO2 coverage. The computational results indicate CO2 capture on the boron phases is a kinetically and thermodynamically feasible process, and therefore from this perspective these boron materials are predicted to be good candidates for CO2 capture.

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

    CERN Document Server

    Har, Jason


    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

  19. Nanoelectronic programmable synapses based on phase change materials for brain-inspired computing. (United States)

    Kuzum, Duygu; Jeyasingh, Rakesh G D; Lee, Byoungil; Wong, H-S Philip


    Brain-inspired computing is an emerging field, which aims to extend the capabilities of information technology beyond digital logic. A compact nanoscale device, emulating biological synapses, is needed as the building block for brain-like computational systems. Here, we report a new nanoscale electronic synapse based on technologically mature phase change materials employed in optical data storage and nonvolatile memory applications. We utilize continuous resistance transitions in phase change materials to mimic the analog nature of biological synapses, enabling the implementation of a synaptic learning rule. We demonstrate different forms of spike-timing-dependent plasticity using the same nanoscale synapse with picojoule level energy consumption.

  20. Electronic structure studies of topological materials (United States)

    Zhou, Shuyun

    Three-dimensional (3D) Dirac fermions are a new class of topological quantum materials. In 3D Dirac semimetals, the conduction and valence bands touch each other at discrete points in the momentum space and show linear dispersions along all momentum directions, forming 3D Dirac cones which are protected by the crystal symmetry. Here I will present our recent studies of the electronic structures of novel materials which host 3D Dirac fermions by using angle-resolved photoemission spectroscopy.

  1. Study of new materials for railgun launchers

    Energy Technology Data Exchange (ETDEWEB)

    Poltanov, A.; Jygailo, N.; Bykov, M.; Glinov, A. [Troitsk Inst. for Innovations and Fusion Research (Russian Federation); Svobodov, A. [State Scientific Technology Center TEMP, Moscow (Russian Federation); Belyakov, A.; Chernetskaya, N. [Mendeleev Univ. of Chemical Technology of Russia, Moscow (Russian Federation)


    The description of new materials which can be used in railgun launchers is presented. Mo-W compositions in the Cu matrix, binary composites with anisotropic conductivity, ceramics and ceramic covers have been studied as materials for rails, solid armature and insulator respectively. The tests have been conducted on a 1m long railgun launcher with a section of the bore 10mm x 10mm using a current with the amplitude 350--400 kA. Main test results are demonstrated.

  2. Lime-Crusted Rammed Earth: Materials Study


    Mileto, Camilla; Vegas López-Manzanares, Fernando; Alejandre, Francisco Javier; Martín, Juan Jesús; Garcia Soriano, Lidia


    This study analyses the durability of rammed-earth wall construction techniques. The analysis focuses on three medieval masonry types from the Castle of Villavieja (Castellón, Spain) using two variations of lime-reinforced rammed earth in its walls: lime-crusted rammed earth and brick-reinforced rammed earth. Materials analysis reveals the good properties of the materials used in the outer wall facing despite its age. It also clearly shows how deterioration depends more on the construction t...

  3. Random-phase approximation and its applications in computational chemistry and materials science (United States)

    Ren, Xinguo; Rinke, Patrick; Joas, Christian; Scheffler, Matthias


    The random-phase approximation (RPA) as an approach for computing the electronic correlation energy is reviewed. After a brief account of its basic concept and historical development, the paper is devoted to the theoretical formulations of RPA, and its applications to realistic systems. With several illustrating applications, we discuss the implications of RPA for computational chemistry and materials science. The computational cost of RPA is also addressed which is critical for its widespread use in future applications. In addition, current correction schemes going beyond RPA and directions of further development will be discussed.

  4. On stochastic FEM based computational homogenization of magneto-active heterogeneous materials with random microstructure (United States)

    Pivovarov, Dmytro; Steinmann, Paul


    In the current work we apply the stochastic version of the FEM to the homogenization of magneto-elastic heterogeneous materials with random microstructure. The main aim of this study is to capture accurately the discontinuities appearing at matrix-inclusion interfaces. We demonstrate and compare three different techniques proposed in the literature for the purely mechanical problem, i.e. global, local and enriched stochastic basis functions. Moreover, we demonstrate the implementation of the isoparametric concept in the enlarged physical-stochastic product space. The Gauss integration rule in this multidimensional space is discussed. In order to design a realistic stochastic Representative Volume Element we analyze actual scans obtained by electron microscopy and provide numerical studies of the micro particle distribution. The SFEM framework described in our previous work (Pivovarov and Steinmann in Comput Mech 57(1): 123-147, 2016) is extended to the case of the magneto-elastic materials. To this end, the magneto-elastic energy function is used, and the corresponding hyper-tensors of the magneto-elastic problem are introduced. In order to estimate the methods' accuracy we performed a set of simulations for elastic and magneto-elastic problems using three different SFEM modifications. All results are compared with "brute-force" Monte-Carlo simulations used as reference solution.

  5. Fuzzy Deduction Material Removal Rate Optimization for Computer Numerical Control Turning

    Directory of Open Access Journals (Sweden)

    Tian-Syung Lan


    Full Text Available Problem statement: Material Removal Rate (MRR is often a major consideration in the modern Computer Numerical Control (CNC turning industry. Most existing optimization researches for CNC finish turning were either accomplished within certain manufacturing circumstances, or achieved through numerous equipment operations. Therefore, a general deduction optimization scheme is deemed to be necessary proposed for the industry. Approach: In this study, four parameters (cutting depth, feed rate, speed, tool nose runoff with three levels (low, medium, high were considered to optimize the MRR in finish turning based on L9(34 orthogonal array. Additionally, nine fuzzy control rules using triangle membership function with respective to five linguistic grades for the MRR is constructed. Considering four input and twenty output intervals, the defuzzification using center of gravity was thus completed for the Taguchi experiment. Therefore, the optimum general deduction parameters can then be received. Results: The confirmation experiment for optimum general deduction parameters was furthermore performed on an ECOCA-3807 CNC lathe. It was shown that the material removal rates from the fuzzy Taguchi deduction optimization parameters are all significantly advanced comparing to those from the benchmark. Conclusion: This study not only proposed a general deduction optimization scheme using orthogonal array, but also contributed the satisfactory fuzzy linguistic approach for the MRR in CNC turning with profound insight.

  6. On stochastic FEM based computational homogenization of magneto-active heterogeneous materials with random microstructure (United States)

    Pivovarov, Dmytro; Steinmann, Paul


    In the current work we apply the stochastic version of the FEM to the homogenization of magneto-elastic heterogeneous materials with random microstructure. The main aim of this study is to capture accurately the discontinuities appearing at matrix-inclusion interfaces. We demonstrate and compare three different techniques proposed in the literature for the purely mechanical problem, i.e. global, local and enriched stochastic basis functions. Moreover, we demonstrate the implementation of the isoparametric concept in the enlarged physical-stochastic product space. The Gauss integration rule in this multidimensional space is discussed. In order to design a realistic stochastic Representative Volume Element we analyze actual scans obtained by electron microscopy and provide numerical studies of the micro particle distribution. The SFEM framework described in our previous work (Pivovarov and Steinmann in Comput Mech 57(1): 123-147, 2016) is extended to the case of the magneto-elastic materials. To this end, the magneto-elastic energy function is used, and the corresponding hyper-tensors of the magneto-elastic problem are introduced. In order to estimate the methods' accuracy we performed a set of simulations for elastic and magneto-elastic problems using three different SFEM modifications. All results are compared with "brute-force" Monte-Carlo simulations used as reference solution.

  7. Computer signal processing for ultrasonic attenuation and velocity measurements for material property characterizations (United States)

    Vary, A.


    This report deals with instrumentation and computer programming concepts that have been developed for ultrasonic materials characterization. Methods that facilitate velocity and attenuation measurements are described. The apparatus described is based on a broadband, buffered contact probe using a pulse-echo approach for simultaneously measuring velocity and attenuation. Instrumentation, specimen condition, and signal acquisition and acceptance criteria are discussed. Typical results with some representative materials are presented.

  8. Recent progress in theoretical and computational investigations of Li-ion battery materials and electrolytes


    Bhatt, Mahesh Datt; O'Dwyer, Colm


    There is an increasing worldwide demand for high energy density batteries. In recent years, rechargeable Li-ion batteries have become important power sources, and their performance gains are driving the adoption of electrical vehicles (EV) as viable alternatives to combustion engines. The exploration of new Li-ion battery materials is an important focus of materials scientists and computational physicists and chemists throughout the world. The practical applications of Li-ion batteries and em...

  9. Model of Integration of Material Flow Control System with MES/ERP System via Cloud Computing

    Directory of Open Access Journals (Sweden)

    Peter Peniak


    Full Text Available This article deals with a model of application gateway for integration of Material Flow Control System with ERP/MES systems, which are provided by Cloud Computing and Software as Service delivery model. The developed gateway interface is supposed to cover fundamental requirements of production systems for customization and real-time control of material flow within manufacturing processes. Designed solution has been tested and evaluated for High Bay Storage system in a real production environment


    Institute of Scientific and Technical Information of China (English)



    In this paper,for an inhomogeneous material in which the thermal conductivity varies as a function of depth,an efficient treatment is proposed to inversely calculate the depth distribution of optical-absorption coefficient by the surface temperature of the material. It is demonstrated that the results of inverse computation by that method are more similar to the experimental ones measured by some destructive method. Thus ,the treatment is more feasible to nondestructively estimate the distribution.

  11. Computational material design for Q&P steels with plastic instability theory

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Guang; Choi, Kyoo Sil; Hu, Xiaohua; Sun, Xin


    In this paper, the deformation limits of Quenching and Partitioning (Q&P) steels are examined with the plastic instability theory. For this purpose, the constituent phase properties of various Q&P steels were first experimentally obtained, and used to estimate the overall tensile stress-strain curves based on the simple rule of mixture (ROM) with the iso-strain and iso-stress assumptions. Plastic instability theory was then applied to the obtained overall stress-strain curves in order to estimate the deformation limits of the Q&P steels. A parametric study was also performed to examine the effects of various material parameters on the deformation limits of Q&P steels. Computational material design was subsequently carried out based on the information obtained from the parametric study. The results show that the plastic instability theory with iso-stress-based stress-strain curve may be used to provide the lower bound estimate of the uniform elongation (UE) for the various Q&P steels considered. The results also indicate that higher austenite stability/volume fractions, less strength difference between the primary phases, higher hardening exponents of the constituent phases are generally beneficial for the performance improvement of Q&P steels, and that various material parameters may be concurrently adjusted in a cohesive way in order to improve the performance of Q&P steel. The information from this study may be used to devise new heat treatment parameters and alloying elements to produce Q&P steels with the improved performance.

  12. Nuclear wasteform materials: Atomistic simulation case studies

    Energy Technology Data Exchange (ETDEWEB)

    Chroneos, A., E-mail: [Materials Engineering, The Open University, Milton Keynes MK7 6AA (United Kingdom); Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Institute of Materials Science, NCSR Demokritos, GR-15310 Athens (Greece); Rushton, M.J.D. [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Jiang, C. [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Tsoukalas, L.H. [Department of Nuclear Engineering, Purdue University, West Lafayette, IN 47907 (United States)


    Ever increasing global energy demand combined with a requirement to reduce CO{sub 2} emissions has rekindled an interest in nuclear power generation. In order that nuclear energy remains publicly acceptable and therefore a sustainable source of power it is important that nuclear waste is dealt with in a responsible manner. To achieve this, improved materials for the long-term immobilisation of waste should be developed. The extreme conditions experienced by nuclear wasteforms necessitate the detailed understanding of their properties and the mechanisms acting within them at the atomic scale. This latter issue is the focus of the present review. Atomic scale simulation techniques can accelerate the development of new materials for nuclear wasteform applications and provide detailed information on their physical properties that cannot be easily accessed by experiment. The present article introduces examples of how atomic scale, computational modelling techniques have led to an improved understanding of current nuclear wasteform materials and also suggest how they may be used in the development of new wasteforms.

  13. Sieveless particle size distribution analysis of particulate materials through computer vision

    Energy Technology Data Exchange (ETDEWEB)

    Igathinathane, C. [Mississippi State University (MSU); Pordesimo, L. O. [Mississippi State University (MSU); Columbus, Eugene P [ORNL; Batchelor, William D [ORNL; Sokhansanj, Shahabaddine [ORNL


    This paper explores the inconsistency of length-based separation by mechanical sieving of particulate materials with standard sieves, which is the standard method of particle size distribution (PSD) analysis. We observed inconsistencies of length-based separation of particles using standard sieves with manual measurements, which showed deviations of 17 22 times. In addition, we have demonstrated the falling through effect of particles cannot be avoided irrespective of the wall thickness of the sieve. We proposed and utilized a computer vision with image processing as an alternative approach; wherein a user-coded Java ImageJ plugin was developed to evaluate PSD based on length of particles. A regular flatbed scanner acquired digital images of particulate material. The plugin determines particles lengths from Feret's diameter and width from pixel-march method, or minor axis, or the minimum dimension of bounding rectangle utilizing the digital images after assessing the particles area and shape (convex or nonconvex). The plugin also included the determination of several significant dimensions and PSD parameters. Test samples utilized were ground biomass obtained from the first thinning and mature stand of southern pine forest residues, oak hard wood, switchgrass, elephant grass, giant miscanthus, wheat straw, as well as Basmati rice. A sieveless PSD analysis method utilized the true separation of all particles into groups based on their distinct length (419 639 particles based on samples studied), with each group truly represented by their exact length. This approach ensured length-based separation without the inconsistencies observed with mechanical sieving. Image based sieve simulation (developed separately) indicated a significant effect (P < 0.05) on number of sieves used in PSD analysis, especially with non-uniform material such as ground biomass, and more than 50 equally spaced sieves were required to match the sieveless all distinct particles PSD analysis

  14. Inquiry-Based Learning Case Studies for Computing and Computing Forensic Students (United States)

    Campbell, Jackie


    Purpose: The purpose of this paper is to describe and discuss the use of specifically-developed, inquiry-based learning materials for Computing and Forensic Computing students. Small applications have been developed which require investigation in order to de-bug code, analyse data issues and discover "illegal" behaviour. The applications…

  15. Computer Assisted Language Learning. Routledge Studies in Computer Assisted Language Learning (United States)

    Pennington, Martha


    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…

  16. Computer Assisted Language Learning. Routledge Studies in Computer Assisted Language Learning (United States)

    Pennington, Martha


    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…

  17. Computation of thermal properties via 3D homogenization of multiphase materials using FFT-based accelerated scheme

    CERN Document Server

    Lemaitre, Sophie; Choi, Daniel; Karamian, Philippe


    In this paper we study the thermal effective behaviour for 3D multiphase composite material consisting of three isotropic phases which are the matrix, the inclusions and the coating media. For this purpose we use an accelerated FFT-based scheme initially proposed in Eyre and Milton (1999) to evaluate the thermal conductivity tensor. Matrix and spherical inclusions media are polymers with similar properties whereas the coating medium is metallic hence better conducting. Thus, the contrast between the coating and the others media is very large. For our study, we use RVEs (Representative volume elements) generated by RSA (Random Sequential Adsorption) method developed in our previous works, then, we compute effective thermal properties using an FFT-based homogenization technique validated by comparison with the direct finite elements method. We study the thermal behaviour of the 3D-multiphase composite material and we show what features should be taken into account to make the computational approach efficient.

  18. 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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B. [Department of Applied Science, University of Arkansas at Little Rock, 2801 South University, ETAS 575, Little Rock, AR 72204-1099 (United States); Bhattacharyya, A., E-mail: axbhattachar@ualr.ed [Department of Applied Science, University of Arkansas at Little Rock, 2801 South University, ETAS 575, Little Rock, AR 72204-1099 (United States)


    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{sub zxx} << d{sub 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.

  19. Computational studies on the crystal structure, thermodynamic properties, detonation performance, and pyrolysis mechanism of 2,4,6,8-tetranitro-1,3,5,7-tetraazacubane as a novel high energy density material. (United States)

    Wang, Fang; Du, Hongchen; Zhang, Jianying; Gong, Xuedong


    Studies have suggested that octanitrocubane (ONC) is one of the most powerful non-nuclear high energy density material (HEDM) currently known. 2,4,6,8-Tetranitro-1,3,5,7-tetraazacubane (TNTAC) studied in this work may also be a novel HEDM due to its high nitrogen content and crystal density. Density functional theory and molecular mechanics methods have been employed to study the crystal structure, IR spectrum, electronic structure, thermodynamic properties, gas-phase and condensed-phase heat of formation, detonation performance, and pyrolysis mechanism of TNTAC. The TNTAC has a predicted density of about 2.12 g/cm(3), and its detonation velocity (10.42 km/s) and detonation pressure (52.82 GPa) are higher than that of ONC. The crystalline packing is P2(1)2(1)2(1), and the corresponding cell parameters are Z = 4, a = 8.87 Å, b = 8.87 Å, and c = 11.47 Å. Both the density of states of the predicted crystal and the bond dissociation energy of the molecule in gas phase show that the cage C-N bond is the trigger bond during thermolysis. The activation energy of the pyrolysis initiation reaction obtained from the B3LYP/6-311++G(2df,2p) level is 125.98 kJ/mol, which indicates that TNTAC meets the thermal stability request as an exploitable HEDM.

  20. The DOE Accelerated Strategic Computing Initiative: Challenges and opportunities for predictive materials simulation capabilities (United States)

    Mailhiot, Christian


    In response to the unprecedented national security challenges emerging from the end of nuclear testing, the Defense Programs of the Department of Energy has developed a long-term strategic plan based on a vigorous Science-Based Stockpile Stewardship (SBSS) program. The main objective of the SBSS program is to ensure confidence in the performance, safety, and reliability of the stockpile on the basis of a fundamental science-based approach. A central element of this approach is the development of predictive, ‘full-physics’, full-scale computer simulation tools. As a critical component of the SBSS program, the Accelerated Strategic Computing Initiative (ASCI) was established to provide the required advances in computer platforms and to enable predictive, physics-based simulation capabilities. In order to achieve the ASCI goals, fundamental problems in the fields of computer and physical sciences of great significance to the entire scientific community must be successfully solved. Foremost among the key elements needed to develop predictive simulation capabilities, the development of improved physics-based materials models is a cornerstone. We indicate some of the materials theory, modeling, and simulation challenges and illustrate how the ASCI program will enable both the hardware and the software tools necessary to advance the state-of-the-art in the field of computational condensed matter and materials physics.

  1. Computational Studies of Magnetically Doped Semiconductor Nanoclusters (United States)

    Gutsev, Lavrenty Gennady

    Spin-polarized unrestricted density functional theory is used to calculate the molecular properties of magnetic semiconductor quantum dots doped with 3d-metal atoms. We calculate total energies of the low spin antiferromagnetically coupled states using a spin-flipping algorithm leading to the broken-symmetry states. Given the novel nature of the materials studied, we simulate experimental observables such as hyperfine couplings, ionization/ energies, electron affinities, first and second order polarizabilities, band gaps and exchange coupling constants. Specifically, we begin our investigation with pure clusters of (CdSe )16 and demonstrate the dependence of molecular observables on geometrical structures. We also show that the many isomers of this cluster are energetically quite closely spaced, and thus it would be necessary to employ a battery of tests to experimentally distinguish them. Next, we discuss Mn-doping into the cage (CdSe)9 cluster as well as the zinc-blende stacking type cluster (CdSe)36. We show that the local exchange coupling mechanism is ligand-mediated superexchange and simulate the isotropic hyperfine constants. Finally, we discuss a novel study where (CdSe)9 is doped with Mn or Fe up to a full replacement of all the Cd's and discuss the transition points for the magnetic behavior and specifically the greatly differing band-gap shifts. We also outline an unexpected pattern in the polarizability of the material as metals are added and compare our results with the results from theoretical studies of the bulk material.

  2. Study on Morph-genetic Materials Derived from Natural Materials

    Directory of Open Access Journals (Sweden)

    Di Zhang


    Full Text Available The way to fabricate novel morph-genetic functional materials based on nature bio-structures is reviewed. We present the idea and methods of obtaining multi-scale porous materials by using wood, agricultural wastes and butterfly wing scales as bio-templates.

  3. Computational studies of plasma lipoprotein lipids. (United States)

    Pan, Lurong; Segrest, Jere P


    Plasma lipoproteins are macromolecular assemblies of proteins and lipids found in the blood. The lipid components of lipoproteins are amphipathic lipids such as phospholipids (PLs), and unesterified cholesterols (UCs) and hydrophobic lipids such as cholesteryl esters (CEs) and triglycerides (TGs). Since lipoproteins are soft matter supramolecular assemblies easily deformable by thermal fluctuations and they also exist in varying densities and protein/lipid components, a detailed understanding of their structure/function is experimentally difficult. Molecular dynamics (MD) simulation has emerged as a particularly promising way to explore the structure and dynamics of lipoproteins. The purpose of this review is to survey the current status of computational studies of the lipid components of the lipoproteins. Computational studies aim to explore three levels of complexity for the 3-dimensional structural dynamics of lipoproteins at various metabolic stages: (i) lipoprotein particles consist of protein with minimal lipid; (ii) lipoprotein particles consist of PL-rich discoidal bilayer-like lipid particles; (iii) mature circulating lipoprotein particles consist of CE-rich or TG-rich spheroidal lipid-droplet-like particles. Due to energy barriers involved in conversion between these species, other biomolecules also participate in lipoprotein biological assembly. For example: (i) lipid-poor apolipoprotein A-I (apoA-I) interacts with ATP-binding cassette transporter A1 (ABCA1) to produce nascent discoidal high density lipoprotein (dHDL) particles; (ii) lecithin-cholesterol acyltransferase (LCAT) mediates the conversion of UC to CE in dHDL, driving spheroidal HDL (sHDL) formation; (iii) transfer proteins, cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP), transfer both CE and TG and PL, respectively, between lipoprotein particles. Computational studies have the potential to explore different lipoprotein particles at each metabolic stage in

  4. The traveling salesman problem a computational study

    CERN Document Server

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


    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.

  5. Computational Study of a Primitive Life Model (United States)

    Andrecut, Mircea

    We present a computational study of a primitive life model. The calculation involves a discrete treatment of a partial differential equation and some details of that problems are explained. We show that the investigated model is equivalent to a diffusively coupled logistic lattice. The bifurcation diagrams were calculated for different values of the control parameters. The obtained diagrams have shown that the time dependence of the population of the investigated model exhibits transitions between ordered and chaotic behavior. We have investigated also the patterns formation in this system.

  6. Molecular modeling of protein materials: case study of elastin (United States)

    Tarakanova, Anna; Buehler, Markus J.


    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.

  7. Material deprivation and health: a longitudinal study. (United States)

    Tøge, Anne Grete; Bell, Ruth


    Does material deprivation affect the consequences of ill health? Answering this question requires that we move beyond the effects of income. Longitudinal data on material deprivation, longstanding illness and limiting longstanding illness enables investigations of the effects of material deprivation on risk of limiting longstanding illness. This study investigates whether a shift from affording to not affording a car predicts the probability of limiting longstanding ill (LLSI). The 2008-2011 longitudinal panel of Statistics on Income, Social Inclusion and Living Conditions (EU-SILC) is utilised. Longitudinal fixed effects logit models are applied, using LLSI as dependent variable. Transition from affording a car to not affording a car is used as a proxy for material deprivation. All models are controlled for whether the person becomes longstanding ill (LSI) as well as other time-variant covariates that could affect the results. The analysis shows a statistically significant increased odds ratio of LLSI when individuals no longer can afford a car, after controlling for confounders and LSI in the previous year (1.129, CI = 1.022-1.248). However, when restricting the sample to observations where respondents report longstanding illness the results are no longer significant (1.032, CI = 0.910-1.171). The results indicate an individual level effect of material deprivation on LLSI, suggesting that material resources can affect the consequences of ill health.

  8. Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy (United States)

    Rowland, Mark S.; Howard, Douglas E.; Wong, James L.; Jessup, James L.; Bianchini, Greg M.; Miller, Wayne O.


    A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.

  9. An integrated computational materials engineering method for woven carbon fiber composites preforming process (United States)

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


    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.

  10. 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


    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.

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



    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 ...

  12. Bioreactor Studies and Computational Fluid Dynamics (United States)

    Singh, H.; Hutmacher, D. W.

    The hydrodynamic environment “created” by bioreactors for the culture of a tissue engineered construct (TEC) is known to influence cell migration, proliferation and extra cellular matrix production. However, tissue engineers have looked at bioreactors as black boxes within which TECs are cultured mainly by trial and error, as the complex relationship between the hydrodynamic environment and tissue properties remains elusive, yet is critical to the production of clinically useful tissues. It is well known in the chemical and biotechnology field that a more detailed description of fluid mechanics and nutrient transport within process equipment can be achieved via the use of computational fluid dynamics (CFD) technology. Hence, the coupling of experimental methods and computational simulations forms a synergistic relationship that can potentially yield greater and yet, more cohesive data sets for bioreactor studies. This review aims at discussing the rationale of using CFD in bioreactor studies related to tissue engineering, as fluid flow processes and phenomena have direct implications on cellular response such as migration and/or proliferation. We conclude that CFD should be seen by tissue engineers as an invaluable tool allowing us to analyze and visualize the impact of fluidic forces and stresses on cells and TECs.

  13. Packaging Materials Outgassing Study Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. A. [Oak Ridge Y-12 Plant (Y-12), Oak Ridge, TN (United States)


    An outgassing study was conducted on two polyurethane packaging foams, two polymer bottles (polytetrafluoroethylene and polyethylene), and two polymer lids. The purpose was to measure the volume of gases that diffuse from these packaging materials at a maximum of 400-degrees F when stored in ambient air within sealed containers.

  14. Gold recycling; a materials flow study (United States)

    Amey, Earle B.


    This materials flow study includes a description of trends in consumption, loss, and recycling of gold-containing materials in the United States in 1998 in order to illustrate the extent to which gold is presently being recycled and to identify recycling trends. The quantity of gold recycled, as a percent of the apparent supply of gold, was estimated to be about 30 percent. Of the approximately 446 metric tons of gold refined in the United States in 1998, the fabricating and industrial use losses were 3 percent.

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

  16. Nanostructure studies of strongly correlated materials. (United States)

    Wei, Jiang; Natelson, Douglas


    Strongly correlated materials exhibit an amazing variety of phenomena, including metal-insulator transitions, colossal magnetoresistance, and high temperature superconductivity, as strong electron-electron and electron-phonon couplings lead to competing correlated ground states. Recently, researchers have begun to apply nanostructure-based techniques to this class of materials, examining electronic transport properties on previously inaccessible length scales, and applying perturbations to drive systems out of equilibrium. We review progress in this area, particularly emphasizing work in transition metal oxides (Fe(3)O(4), VO(2)), manganites, and high temperature cuprate superconductors. We conclude that such nanostructure-based studies have strong potential to reveal new information about the rich physics at work in these materials.

  17. Whither the Material in New Media Studies?

    Directory of Open Access Journals (Sweden)

    John W. Kim


    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.

  18. A computer study of biodegradable plates for internal fixation of mandibular angle fractures

    NARCIS (Netherlands)

    Tams, J; Van Loon, JP; Otten, B; Bos, RRM


    Purpose: This computer-based study was performed to determine the suitability of small biodegradable plate systems for mandibular angle fractures. Materials and Methods: In a 3-dimensional computer model of the mandible, fracture mobility and plate strain were calculated for bite forces applied on 1

  19. The Study of the Thermoelectric Properties of Phase Change Materials (United States)

    Yin, Ming; Abdi, Mohammed; Noimande, Zibusisu; Mbamalu, Godwin; Alameeri, Dheyaa; Datta, Timir

    We study thermoelectric property that is electrical phenomena occurring in conjunction with the flow of heat of phase-change materials (PCM) in particular GeSbTe (GST225). From given sets of material parameters, COMSOL Multiphysics heat-transfer module is used to compute maps of temperature and voltage distribution in the PCM samples. These results are used to design an apparatus including the variable temperature sample holder set up. An Arbitrary/ Function generator and a circuit setup is also designed to control the alternation of heaters embedded on the sample holder in order to ensure sequential back and forward flow of heat current from both sides of the sample. Accurate values of potential differences and temperature distribution profiles are obtained in order to compute the Seebeck coefficient of the sample. The results of elemental analysis and imaging studies such as XRD, UV-VIS, EDEX and SEM of the sample are obtained. Factors affecting the thermoelectric properties of phase change memory are also discussed. NNSA/ DOD Consortium for Materials and Energy Studies.

  20. Experimental and computational thermochemical study of oxindole

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, Margarida S., E-mail: msmirand@fc.up.p [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Centro de Geologia da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Matos, M. Agostinha R., E-mail: marmatos@fc.up.p [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Morais, Victor M.F., E-mail: vmmorais@icbas.up.p [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Instituto de Ciencias Biomedicas Abel Salazar, ICBAS, Universidade do Porto, P-4099-003 Porto (Portugal); Liebman, Joel F., E-mail: jliebman@umbc.ed [Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, MD 21250 (United States)


    An experimental and computational thermochemical study was performed for oxindole. The standard (p{sup 0}=0.1MPa) molar enthalpy of formation of solid oxindole was derived from the standard molar energy of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The respective standard molar enthalpy of sublimation, at T = 298.15 K, was measured by Calvet microcalorimetry. The standard molar enthalpy of formation in the gas phase was derived as -(66.8 {+-} 3.2) kJ . mol{sup -1}. Density functional theory calculations with the B3LYP hybrid functional and the 6-31G* and 6-311G** sets have also been performed in order to obtain the most stable conformation of oxindole. A comparison has been made between the structure of oxindole and that of the related two-ring molecules: indoline and 2-indanone and the one-ring molecules: pyrrolidine and 2,3-dihydropyrrole. The G3(MP2)//B3LYP method and appropriate reactions were used to obtain estimates of the standard molar enthalpy of formation of oxindole in the gas phase, at T = 298.15 K. Computationally obtained estimates of the enthalpy of formation of oxindole are in very good agreement with the experimental gas phase value. The aromaticity of oxindole was evaluated through the analysis of the nucleus independent chemical shifts (NICS) obtained from the B3LYP/6-311G** wave functions.

  1. 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)


    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.

  2. 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


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  4. Computer program for prediction of the deposition of material released from fixed and rotary wing aircraft (United States)

    Teske, M. E.


    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.

  5. Computational Identification of Promising Thermoelectric Materials Among Known Quasi-2D Binary Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gorai, Prashun; Toberer, Eric S.; Stevanovic, Vladan


    Quasi low-dimensional structures are abundant among known thermoelectric materials, primarily because of their low lattice thermal conductivities. In this work, we have computationally assessed the potential of 427 known binary quasi-2D structures in 272 different chemistries for thermoelectric performance. To assess the thermoelectric performance, we employ an improved version of our previously developed descriptor for thermoelectric performance [Yan et al., Energy Environ. Sci., 2015, 8, 983]. The improvement is in the explicit treatment of van der Waals interactions in quasi-2D materials, which leads to significantly better predictions of their crystal structures and lattice thermal conductivities. The improved methodology correctly identifies known binary quasi-2D thermoelectric materials such as Sb2Te3, Bi2Te3, SnSe, SnS, InSe, and In2Se3. As a result, we propose candidate quasi-2D binary materials, a number of which have not been previously considered for thermoelectric applications.

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

    CERN Document Server

    Pisano, Aurora; Weichert, Dieter


    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...

  7. Computer-based support for science education materials developers in Africa : exploring potentials

    NARCIS (Netherlands)

    McKenney-Jensh, Susan E.


    CASCADE-SEA stands for Computer Assisted Curriculum Analysis, Design and Evaluation for Science (and mathematics) Education in Africa; and is the name of a computer program that was developed during the course of the study described in this book. This research was initiated to explore the potential

  8. 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)


    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.

  9. Preservation of adobe buildings. Study of materials (United States)

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


    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.

  10. Finite element computer program for the calculation of the resonant frequencies of anisotropic materials

    Energy Technology Data Exchange (ETDEWEB)

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


    A set of computer programs for the calculation of the flexural and torsional resonant frequencies of rectangular section bars of materials of orthotropic or high 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. (auth)

  11. Development studies of captopril certified reference material

    Directory of Open Access Journals (Sweden)

    Raquel Nogueira


    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.


    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...

  13. Post Graduate Students' Computing Confidence, Computer and Internet Usage at Kuvempu University--An Indian Study (United States)

    Dange, Jagannath K.


    There is a common belief that students entering Post Graduation have appropriate computing skills for study purposes and there is no longer a felt need for computer training programmes in tertiary education. First year students of Post Graduation were surveyed in 2009, they were asked about their Education and Computing backgrounds. Further, the…

  14. Computer Competency: A 7-Year Study to Identify Gaps in Student Computer Skills (United States)

    Shuster, George F.; Pearl, Mona


    Computer competency is crucial to student success in higher education. Assessment of student knowledge related to specific computer competencies can provide faculty with important information about the strengths and weaknesses of their students' computer competency skills. The purpose of this study was to identify the competency level of two…

  15. A hyperspectral X-ray computed tomography system for enhanced material identification (United States)

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


    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.

  16. A computer program for predicting nonlinear uniaxial material responses using viscoplastic models (United States)

    Chang, T. Y.; Thompson, R. L.


    A computer program was developed for predicting nonlinear uniaxial material responses using viscoplastic constitutive models. Four specific models, i.e., those due to Miller, Walker, Krieg-Swearengen-Rhode, and Robinson, are included. Any other unified model is easily implemented into the program in the form of subroutines. Analysis features include stress-strain cycling, creep response, stress relaxation, thermomechanical fatigue loop, or any combination of these responses. An outline is given on the theoretical background of uniaxial constitutive models, analysis procedure, and numerical integration methods for solving the nonlinear constitutive equations. In addition, a discussion on the computer program implementation is also given. Finally, seven numerical examples are included to demonstrate the versatility of the computer program developed.

  17. In-Service Design & Performance Prediction of Advanced Fusion Material Systems by Computational Modeling and Simulation

    Energy Technology Data Exchange (ETDEWEB)

    G. R. Odette; G. E. Lucas


    This final report on "In-Service Design & 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, 3-f) 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.

  18. Design for hydrogen storage materials via observation of adsorption sites by computer tomography. (United States)

    Zhang, Li; Wang, Qi; Liu, Ying-Chun


    An effective method denoted as "computer tomography for materials" (mCT) was employed to study the adsorption sites inside metal-organic frameworks (MOFs) at any positions and any view angles. For MOF-5, the first adsorption site alpha(-COO)3 was clearly observed from the mCT images; it locates at the position where three -COO groups joined like a cup. There are four alpha(-COO)3 sites around the Zn4O cluster. Two of them located at the diagonal of the Zn4O cluster are in the same plane "A", whereas the other two equivalent adsorption sites are in another plane "B", which is about 5.4 A away from the plane A. It was found that the electronegativity of oxygen atoms is very important to the adsorption of hydrogen molecules. The hydrogen amount adsorbed in MOFs might be enhanced by introducing some strong electronegative atoms to the organic linkers or frameworks. On the basis of this point of view, five new MOF materials were designed. The adsorbed amounts both in number of hydrogen molecules per unit cell and weight uptake for all of the designed MOFs were calculated. The adsorption amounts of designed MOFs were improved, and the amount for MOF-d5 at 1 bar is as high as 3.7 wt %. It is nearly 5-6 times of that of MOF-5 as a whole. It can be observed that extra adsorption sites were formed in the pores and the effective occupation rate of pore space was obviously improved viewing from the mCT images. These results may give helpful suggestions for the synthetic experimentalists.

  19. Study guide to accompany computers data and processing

    CERN Document Server

    Deitel, Harvey M


    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

  20. Computing at Brown--An Ongoing Study. (United States)

    Shields, Mark


    Discusses conclusions based on results of two Brown University research projects aimed at understanding social and educational significance of computing in higher education: 1984 university-wide survey of students, faculty, and staff, and a 1985 survey of incoming freshmen. The conclusions discussed relate to computer use, experience, attitudes,…

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

    Energy Technology Data Exchange (ETDEWEB)

    Muthurajan, H. [Armament Research and Development Establishment, Pashan, Pune 411021 (India)], E-mail:; Sivabalan, R.; Pon Saravanan, N.; Talawar, M.B. [High Energy Materials Research Laboratory, Sutarwadi, Pune 411 021 (India)


    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 ({delta}H{sub 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{sup 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.

  2. Computer code to predict the heat of explosion of high energy materials. (United States)

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


    The computational approach to the thermochemical changes involved in the process of explosion of a high energy materials (HEMs) vis-à-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 (DeltaH(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.

  3. Effective magnetic field computation in Tokamaks in presence of magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Chiariello, Andrea G.; Formisano, Alessandro [Dip. di Ing. Industriale e dell’Informazione, Seconda Università di Napoli, Via Roma 29, I-81031 Napoli (Italy); Fresa, Raffaele [Scuola di Ingegneria, Università della Basilicata, Potenza (Italy); Consorzio EURATOM/ENEA/CREATE (Italy); Ledda, Francesco, E-mail: [Dip. di Ing. Industriale e dell’Informazione, Seconda Università di Napoli, Via Roma 29, I-81031 Napoli (Italy); Martone, Raffaele; Pizzo, Francesco [Dip. di Ing. Industriale e dell’Informazione, Seconda Università di Napoli, Via Roma 29, I-81031 Napoli (Italy)


    Magnetic materials play an important role in the magnetic fields distribution inside Tokamaks, and their contributions must be carefully computed. In some applications, when 3D geometries are involved and high accuracy must be achieved, finite elements may reveal too computationally demanding and different approaches must be considered. In this paper, two possible solutions are presented. The first one is based on the discretization of magnetic parts into rectangular prisms with constant magnetization density; analytical formulas are then used to compute the field contribution due to each brick. The second one is based on the representation of the effect of magnetic materials as a set of dipoles, by using again analytical formulas to evaluate the contribution to the magnetic field. Iterative procedures are applied to evaluate the magnetization density in prisms. The efficiency and accuracy of both models are validated against commercial codes on a test case, and then applied to the computation of magnetic field in presence of Neutral Beam Injector in an ITER-like geometry.

  4. Theory, Modeling, Software and Hardware Development for Analytical and Computational Materials Science (United States)

    Young, Gerald W.; Clemons, Curtis B.


    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.

  5. Environmental reference materials methods and case studies

    DEFF Research Database (Denmark)

    Schramm-Nielsen, Karina Edith


    This thesis introduces the reader to the concept of chemical environmental reference materials and their role in traceability and chemical analyses of the environment. A number of models and principles from the literature are described. Some suggestions are made as to how stability studies can...... be modelled when the length of the study is unknown. Experimental data has been collected from two stability studies of aqueous matrices. The first study regards the stability of TN NO² + ³-N and n in autoclaved wastewater samples over a period of 22 months. Data was collected specifically for this study...... with two purposes: 1) to investigate the stability of selected analytes in the chosen matrices and 2) to explore the applicability of various statistical models for the description of stability studies. Three univariate and three multivariate stability models have been applied to these data sets...

  6. Computational diffusion kinetics and its applications in study and design of rare metallic materials%计算扩散动力学在稀有金属材料研究和设计中的应用

    Institute of Scientific and Technical Information of China (English)

    CUI YuWen; XU GuangLong; CHEN Yi; 唐斌; 李金山; 周廉


    计算扩散动力学(computational diffusion kinetics,CDK)因采用与计算热力学(computational thermodynamics,CT)或称为CALPHAD(CALculation of PHAse Diagram)技术相同的Redlich-Kister外推数学模型并与其高度集成,从而可以准确提供多元合金的扩散动力学信息,因此在合金材料的成分设计和微观组织控制中起着日益重要的作用.本文综述了计算扩散动力学在以钛及锆合金为代表的稀有金属材料研究中的最新进展,阐述了计算扩散动力学与计算热力学、定量相场(phase field)模拟以及三维统计计算(3D statistical calculation)结合用于设计(α+β)钛6-4合金热处理工艺的研究.

  7. Energetic oxygen atom material degradation studies (United States)

    Caledonia, George E.; Krech, Robert H.


    As part of a study designed to test potential Shuttle surface materials for the extents of degradation and mass loss expected to be suffered in space from the velocity impacts of ambient oxygen atoms, a novel technique was developed for generation of a high flux of energetic oxygen atoms. The generation technique involves laser-induced breakdown of molecular oxygen followed by a rapid expansion of energetic oxygen atoms. The high-velocity streams developed in an evacuated hypersonic nozzle have average O-atom velocities of about 5 to 13 km/s, with an estimated total production of 10 to the 18th atoms per pulse over pulse durations of several microseconds. Results on preliminary material degradation tests conducted with this test facility have been reported by Caledonia et al. (1987). Diagrams of the experimental setup are included.

  8. Raw material studies of West Central Serbia

    Directory of Open Access Journals (Sweden)

    Vera Bogosavljević Petrović


    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. Development of the material selection practice - a study exploring articulation of material requirements

    DEFF Research Database (Denmark)

    Lenau, Torben Anker; Hasling, Karen Marie


    This paper explores how the material selection matrix is used in a materials and sustainability course. The matrix encourages the students to articulate material selection requirements to become more competent in exploring new materials and selecting materials for a given design task. The study...

  10. Integrating Molecular Computation and Material Production in an Artificial Subcellular Matrix

    DEFF Research Database (Denmark)

    Fellermann, Harold; Hadorn, Maik; Bönzli, Eva

    Living systems are unique in that they integrate molecular recognition and information processing with material production on the molecular scale. Pre- dominant locus of this integration is the cellular matrix, where a multitude of biochemical reactions proceed simultaneously in highly compartmen......Living systems are unique in that they integrate molecular recognition and information processing with material production on the molecular scale. Pre- dominant locus of this integration is the cellular matrix, where a multitude of biochemical reactions proceed simultaneously in highly...... compartmentalized re- action compartments that interact and get delivered through vesicle trafficking. The European Commission funded project MatchIT (Matrix for Chemical IT) aims at creating an artificial cellular matrix that seamlessly integrates infor- mation processing and material production in much the same...... way as its biological counterpart: the project employs addressable chemical containers (chemtainers) interfaced with electronic computers via mechano-electronic microfluidics....

  11. An algorithm for noise correction of dual-energy computed tomography material density images. (United States)

    Maia, Rafael Simon; Jacob, Christian; Hara, Amy K; Silva, Alvin C; Pavlicek, William; Ross, Mitchell J


    Dual-energy computed tomography (DECT) images can undergo a two-material decomposition process which results in two images containing material density information. Material density images obtained by that process result in images with increased pixel noise. Noise reduction in those images is desirable in order to improve image quality. A noise reduction algorithm for material density images was developed and tested. A three-level wavelet approach combined with the application of an anisotropic diffusion filter was used. During each level, the resulting noise maps are further processed, until the original resolution is reached and the final noise maps obtained. Our method works in image space and, therefore, can be applied to any type of material density images obtained from any DECT vendor. A quantitative evaluation of the noise-reduced images using the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and 2D noise power spectrum was done to quantify the improvements. The noise reduction algorithm was applied to a set of images resulting in images with higher SNR and CNR than the raw density images obtained by the decomposition process. The average improvement in terms of SNR gain was about 49 % while CNR gain was about 52 %. The difference between the raw and filtered regions of interest mean values was far from reaching statistical significance (minimum [Formula: see text], average [Formula: see text]). We have demonstrated through a series of quantitative analyses that our novel noise reduction algorithm improves the image quality of DECT material density images.


    Directory of Open Access Journals (Sweden)

    Gulyaev Valeriy Genrihovich


    Full Text Available The article covers the issues of development and the results of the pilot testing of the contact-free meter of the two-phase flow of loose construction materials in the course of their pneumatic transportation. The flow meter designed by the author is based on the method of registration of polarization currents caused by the motion of the dielectric material within the electric field of a measurement unit integrated into the pneumatic transportation line. The registration unit is the implementation of the original technology. Its functional concept is based on the Pockels transverse effect inside the lithium niobate crystal. This electro-optical effect is characterized by minimal persistence, as the phase of the optical wave varies within the time period of 10 second, and this effect makes it possible to improve the accuracy of measurements. The flow rates is identified on the basis of one variable integral parameter, the intensity of an optical wave passing through the Pockels cell simulated by the currents of polarization of the material. The paper contains the structural pattern of the computer-aided meter of loose dielectric materials in the course of their pneumatic transportation, the system of visualization of the mass flow, and the results of the pilot testing of the proposed meter. The proposed system may represent an unbiased system of management of construction materials, consumption procedures, and warehouse processing of materials.

  13. Modifications in the AA5083 Johnson-Cook Material Model for Use in Friction Stir Welding Computational Analyses (United States)


    REPORT Modifications in the AA5083 Johnson-Cook Material Model for Use in Friction Stir Welding Computational Analyses 14. ABSTRACT 16. SECURITY...TERMS AA5083, friction stir welding , Johnson-Cook material model M. Grujicic, B. Pandurangan, C.-F. Yen, B. A. Cheeseman Clemson University Office of...Use in Friction Stir Welding Computational Analyses Report Title ABSTRACT Johnson-Cook strength material model is frequently used in finite-element

  14. A Study on Use of Computer among Higher Secondary Students as Related with Their Computer Anxiety, Internet Attitude and Self-Efficacy in Computer (United States)

    Vinaitheerthan, V.; Johnson, Jomy


    The present attempt is to study the use of computer and its possible relationship to Internet attitude, self-efficacy in computer and computer anxiety among higher secondary students. The present study aims at finding the levels of use of computer, Internet attitude, Self-efficacy in computer and computer anxiety among higher secondary students.…

  15. Computational Studies of Protein Hydration Methods (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

  16. Study Development of the Cardiac Computer Simulations

    Institute of Scientific and Technical Information of China (English)

    VOLKERHellemanns; ZHANGHong; SEKOUSingare; ZHANGZhen-xi; KONGXiang-yun


    The technique of computer simulations is a very efficient method in investigating mechanisms of many diseases. This paper reviews how the simulations of the human heart started as a simple mathematical models in the past and developed to the point where genetic information is needed to do suitable work like finding out new medicaments against heart diseases. Also the Influence of the development of computer performance in the future as well as the data presentation is described.

  17. Investigation of the effects of storage time on the dimensional accuracy of impression materials using cone beam computed tomography (United States)


    PURPOSE The storage conditions of impressions affect the dimensional accuracy of the impression materials. The aim of the study was to assess the effects of storage time on dimensional accuracy of five different impression materials by cone beam computed tomography (CBCT). MATERIALS AND METHODS Polyether (Impregum), hydrocolloid (Hydrogum and Alginoplast), and silicone (Zetaflow and Honigum) impression materials were used for impressions taken from an acrylic master model. The impressions were poured and subjected to four different storage times: immediate use, and 1, 3, and 5 days of storage. Line 1 (between right and left first molar mesiobuccal cusp tips) and Line 2 (between right and left canine tips) were measured on a CBCT scanned model, and time dependent mean differences were analyzed by two-way univariate and Duncan's test (α=.05). RESULTS For Line 1, the total mean difference of Impregum and Hydrogum were statistically different from Alginoplast (P<.05), while Zetaflow and Honigum had smaller discrepancies. Alginoplast resulted in more difference than the other impressions (P<.05). For Line 2, the total mean difference of Impregum was statistically different from the other impressions. Significant differences were observed in Line 1 and Line 2 for the different storage periods (P<.05). CONCLUSION The dimensional accuracy of impression material is clinically acceptable if the impression material is stored in suitable conditions. PMID:27826388

  18. Towards new green high energy materials. Computational chemistry on nitro-substituted urea. (United States)

    Wagner, Rachelle R; Ball, David W


    As part of a series of studies on new potential green high energy materials, we have calculated the structures and properties of a series of nitro-substituted urea molecules. Our results indicate that nitrated urea molecules have specific enthalpies of decomposition commensurate with current high energy materials. At the same time, they are all low in carbon, suggesting an application as a "green" high energy material.

  19. Computing effective properties of random heterogeneous materials on heterogeneous parallel processors (United States)

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


    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.

  20. Estimation of the physico-chemical parameters of materials based on rare earth elements with the application of computational model (United States)

    Mamaev, K.; Obkhodsky, A.; Popov, A.


    Computational model, technique and the basic principles of operation program complex for quantum-chemical calculations of material's physico-chemical parameters with rare earth elements are discussed. The calculating system is scalable and includes CPU and GPU computational resources. Control and operation of computational jobs and also Globus Toolkit 5 software provides the possibility to join computer users in a unified system of data processing with peer-to-peer architecture. CUDA software is used to integrate graphic processors into calculation system.

  1. Computational materials science aided design of glass ceramics and crystal properties (abstract only). (United States)

    Mannstadt, Wolfgang


    Today's high tech materials have in many cases highly specialized properties and designed functionalities. Materials parameters like high temperature stability, high stiffness and certain optical properties have to be optimized and in many cases an adaptation to given processes is necessary. Many materials are compounds or layered structures. Thus, surface and interface properties need to be considered as well. At the same time to some extent just a few atomic layers sometimes determine the properties of the material, as is well known in semiconductor and other thin film technologies. Therefore, a detailed understanding of the materials properties at the atomic scale becomes more and more important. In addition many high tech materials have to be of high purity or selective dopant concentrations have to be adjusted to fulfill the desired functionality. Modern materials developments successfully use computational materials science to achieve that goal. Improved software tools and continuously growing computational power allow us to predict macroscopic properties of materials on the basis of microscopic/atomic ab initio simulation approaches. At Schott, special materials, in particular glasses and glass ceramics, are produced for a variety of applications. For a glass ceramic all the above mentioned difficulties for materials development arise. The properties of a glass ceramic are determined by the interplay of crystalline phases embedded in an amorphous glass matrix. For materials development the understanding of crystal structures and their properties, surfaces and interface phenomena, and amorphous systems are necessary, likewise. Each by itself is already a challenging problem. Many crystal phases that are grown within the glass matrix do not exist as single crystals or are difficult to grow in reasonable amounts for experimental investigations. The only way to obtain the properties of these crystalline phases is through 'ab initio' simulations in the computer

  2. Virtual earthquake engineering laboratory with physics-based degrading materials on parallel computers (United States)

    Cho, In Ho

    particle-soft matrix to explain realistic interlocking over rough crack surfaces, and the adopted Gaussian distribution feeds random particle sizes to the entire domain. Validation against a well-documented rough crack experiment reveals promising accuracy of the proposed 3d interlocking model. A consumed energy-based damage model has been proposed for the weak correlation between the normal and shear stresses on the crack surfaces, and also for describing the nature of irrecoverable damage. Since the evaluation of the consumed energy is directly linked to the microscopic deformation, which can be efficiently tracked on the crack surfaces, the proposed damage model is believed to provide a more physical interpretation than existing damage mechanics, which fundamentally stem from mathematical derivation with few physical counterparts. Another novel point of the present work lies in the topological transition-based "smart" steel bar model, notably with evolving compressive buckling length. We presented a systematic framework of information flow between the key ingredients of composite materials (i.e., steel bar and its surrounding concrete elements). The smart steel model suggested can incorporate smooth transition during reversal loading, tensile rupture, early buckling after reversal from excessive tensile loading, and even compressive buckling. Especially, the buckling length is made to evolve according to the damage states of the surrounding elements of each bar, while all other dominant models leave the length unchanged. What lies behind all the aforementioned novel attempts is, of course, the problem-optimized parallel platform. In fact, the parallel computing in our field has been restricted to monotonic shock or blast loading with explicit algorithm which is characteristically feasible to be parallelized. In the present study, efficient parallelization strategies for the highly demanding implicit nonlinear finite element analysis (FEA) program for real

  3. An Image-Domain Contrast Material Extraction Method for Dual-Energy Computed Tomography. (United States)

    Lambert, Jack W; Sun, Yuxin; Gould, Robert G; Ohliger, Michael A; Li, Zhixi; Yeh, Benjamin M


    Conventional material decomposition techniques for dual-energy computed tomography (CT) assume mass or volume conservation, where the CT number of each voxel is fully assigned to predefined materials. We present an image-domain contrast material extraction process (CMEP) method that preferentially extracts contrast-producing materials while leaving the remaining image intact. Image processing freeware (Fiji) is used to perform consecutive arithmetic operations on a dual-energy ratio map to generate masks, which are then applied to the original images to generate material-specific images. First, a low-energy image is divided by a high-energy image to generate a ratio map. The ratio map is then split into material-specific masks. Ratio intervals known to correspond to particular materials (eg, iodine, calcium) are assigned a multiplier of 1, whereas ratio values in between these intervals are assigned linear gradients from 0 to 1. The masks are then multiplied by an original CT image to produce material-specific images. The method was tested quantitatively at dual-source CT and rapid kVp-switching CT (RSCT) with phantoms using pure and mixed formulations of tungsten, calcium, and iodine. Errors were evaluated by comparing the known material concentrations with those derived from the CMEP material-specific images. Further qualitative evaluation was performed in vivo at RSCT with a rabbit model using identical CMEP parameters to the phantom. Orally administered tungsten, vascularly administered iodine, and skeletal calcium were used as the 3 contrast materials. All 5 material combinations-tungsten, iodine, and calcium, and mixtures of tungsten-calcium and iodine-calcium-showed distinct dual-energy ratios, largely independent of material concentration at both dual-source CT and RSCT. The CMEP was successful in both phantoms and in vivo. For pure contrast materials in the phantom, the maximum error between the known and CMEP-derived material concentrations was 0.9 mg

  4. Optical Studies on Rare Earth Lasting Materials

    Directory of Open Access Journals (Sweden)

    S.P. Tandon


    Full Text Available Neodymium-doped borate and phosphate glass specimens have been prepared by melt-quenching technique. Their absorption spectra have been recorded in the region 400 -900 nm. From observed absorption spectra,Judd Ofelt (J0, Omega/sub t/, parameters (t = 2, 4 and 6 have been computed. They have been used to calculate the laser parameters, viz., spontaneous emission probability (A, fluorescence branching ratio (Beeta and stimulated emission cross-section (Sigma. They exhibit the suitability of the present glass specimen for laser action. The effects of composition and concentration of the dopant on these parameters have been discussed. A comparative study of stimulated emission cross-section of different types of doped glasses has also been made.


    Directory of Open Access Journals (Sweden)

    Jagannath K. Dange


    Full Text Available There is a common belief that students entering Post Graduation have appropriate computing skills for study purposes and there is no longer a felt need for computer training programmes in tertiary education. First year students of Post Graduation were surveyed in 2009, they were asked about their Education and Computing backgrounds. Further, the elaboration of issues raised was gathered through focused interviews. Collected data was then analyzed through the percentage analysis. Nowadays Indian regional students have higher confidence in their Computing abilities. One clear reason as it appears, the increased access to Computers and the Internet confidence. They are also likely to contradict Knowledge and Confidence. Surprisingly, the survey results showed high usage extent of Computer Training Programmes. Therefore, the revoking of Computer Training Programmes for all P.G courses with Indian educational standards is not recommended.

  6. Discovery of novel hydrogen storage materials: an atomic scale computational approach. (United States)

    Wolverton, C; Siegel, Donald J; Akbarzadeh, A R; Ozoliņš, V


    Practical hydrogen storage for mobile applications requires materials that exhibit high hydrogen densities, low decomposition temperatures, and fast kinetics for absorption and desorption. Unfortunately, no reversible materials are currently known that possess all of these attributes. Here we present an overview of our recent efforts aimed at developing a first-principles computational approach to the discovery of novel hydrogen storage materials. Such an approach requires several key capabilities to be effective: (i) accurate prediction of decomposition thermodynamics, (ii) prediction of crystal structures for unknown hydrides, and (iii) prediction of preferred decomposition pathways. We present examples that illustrate each of these three capabilities: (i) prediction of hydriding enthalpies and free energies across a wide range of hydride materials, (ii) prediction of low energy crystal structures for complex hydrides (such as Ca(AlH(4))(2) CaAlH(5), and Li(2)NH), and (iii) predicted decomposition pathways for Li(4)BN(3)H(10) and destabilized systems based on combinations of LiBH(4), Ca(BH(4))(2) and metal hydrides. For the destabilized systems, we propose a set of thermodynamic guidelines to help identify thermodynamically viable reactions. These capabilities have led to the prediction of several novel high density hydrogen storage materials and reactions.

  7. Computational study on structure and properties of new energetic material 3,7-bis(dinitromethylene-2,4,6,8-tetranitro-2,4,6,8-tetraaza-bicyclo[3.3.0]octane

    Directory of Open Access Journals (Sweden)

    Xinghui Jin


    Full Text Available The IR spectrum, crystal structure, electronic structure, thermodynamic properties, heat of formation and detonation properties of a new polynitro heterocyclic energetic material 3,7-bis(dinitromethylene-2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo[3.3.0]octane were investigated theoretically. The calculated results show that this compound has a centrosymmetric structure and the molecular packing prediction indicates that the crystalline packing of the title compound is P212121 and the corresponding cell parameters are as follows: Z=4, a= 22.03 Å, b=8.73 Å, c=8.42 Å, Ꮁ=90°, β=90° and γ=90°. Based on the high positive heat of formation (HOF, 740.4 kJ mol-1, excellent detonation properties (detonation velocity D, 9.77 km s−1; detonation pressure P, 45.9 GPa, energy gap (ΔELUMO-HOMO 4.19 eV and the molecular electrostatic potentials (MEP, it is predicted that 3,7-bis(dinitromethylene-2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo[3.3.0] octane could be may be a superior high-energy density compound (HEDC to RDX and HMX.

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

    Directory of Open Access Journals (Sweden)

    Christine A McLachlan


    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

  9. A Study of Computing Undergraduates Undertaking a Systematic Literature Review (United States)

    Brereton, P.


    Teaching computing students about the importance of evidence and about the use of empirical methods for evaluating computing technologies can be difficult, especially within dual honors undergraduate degree programs. The aims of this study were to explore the effectiveness of second-year undergraduate computing students in carrying out a…

  10. A Study of Computing Undergraduates Undertaking a Systematic Literature Review (United States)

    Brereton, P.


    Teaching computing students about the importance of evidence and about the use of empirical methods for evaluating computing technologies can be difficult, especially within dual honors undergraduate degree programs. The aims of this study were to explore the effectiveness of second-year undergraduate computing students in carrying out a…

  11. Computer-aided analysis for the Mechanics of Granular Materials (MGM) experiment, part 2 (United States)

    Parker, Joey K.


    Computer vision based analysis for the MGM experiment is continued and expanded into new areas. Volumetric strains of granular material triaxial test specimens have been measured from digitized images. A computer-assisted procedure is used to identify the edges of the specimen, and the edges are used in a 3-D model to estimate specimen volume. The results of this technique compare favorably to conventional measurements. A simplified model of the magnification caused by diffraction of light within the water of the test apparatus was also developed. This model yields good results when the distance between the camera and the test specimen is large compared to the specimen height. An algorithm for a more accurate 3-D magnification correction is also presented. The use of composite and RGB (red-green-blue) color cameras is discussed and potentially significant benefits from using an RGB camera are presented.

  12. Computational two-dimensional modeling of the stress intensity factor in a cracked metallic material (United States)

    Rolón, J. E.; Cendales, E. D.; Cruz, I. M.


    Cracking of metallic engineering materials is of great importance due cost of replacing mechanical elements cracked and the danger of sudden structural failure of these elements. One of the most important parameters during consideration of the mechanical behavior of machine elements having cracking and that are subject to various stress conditions is the stress intensity factor near the crack tip called factor Kic. In this paper a computational model is developed for the direct assessment of stress concentration factor near to the crack tip and compared with the results obtained in the literature in which other models have been established, which consider continuity of the displacement of the crack tip (XBEM). Based on this numerical approximation can be establish that computational XBEM method has greater accuracy in Kic values obtained than the model implemented by the method of finite elements for the virtual nodal displacement through plateau function.

  13. Approximation method to compute domain related integrals in structural studies (United States)

    Oanta, E.; Panait, C.; Raicu, A.; Barhalescu, M.; Axinte, T.


    Various engineering calculi use integral calculus in theoretical models, i.e. analytical and numerical models. For usual problems, integrals have mathematical exact solutions. If the domain of integration is complicated, there may be used several methods to calculate the integral. The first idea is to divide the domain in smaller sub-domains for which there are direct calculus relations, i.e. in strength of materials the bending moment may be computed in some discrete points using the graphical integration of the shear force diagram, which usually has a simple shape. Another example is in mathematics, where the surface of a subgraph may be approximated by a set of rectangles or trapezoids used to calculate the definite integral. The goal of the work is to introduce our studies about the calculus of the integrals in the transverse section domains, computer aided solutions and a generalizing method. The aim of our research is to create general computer based methods to execute the calculi in structural studies. Thus, we define a Boolean algebra which operates with ‘simple’ shape domains. This algebraic standpoint uses addition and subtraction, conditioned by the sign of every ‘simple’ shape (-1 for the shapes to be subtracted). By ‘simple’ shape or ‘basic’ shape we define either shapes for which there are direct calculus relations, or domains for which their frontiers are approximated by known functions and the according calculus is carried out using an algorithm. The ‘basic’ shapes are linked to the calculus of the most significant stresses in the section, refined aspect which needs special attention. Starting from this idea, in the libraries of ‘basic’ shapes, there were included rectangles, ellipses and domains whose frontiers are approximated by spline functions. The domain triangularization methods suggested that another ‘basic’ shape to be considered is the triangle. The subsequent phase was to deduce the exact relations for the

  14. Experimental and computational studies of nanofluids (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


    CERN Multimedia

    I. Fisk


    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 ...

  16. Computer-based studies on enzyme catalysis

    NARCIS (Netherlands)

    Ridder, L.


    Theoretical simulations are becoming increasingly important for our understanding of how enzymes work. The aim of the research presented in this thesis is to contribute to this development by applying various computational methods to three enzymes of theβ-ketoadipate pathway, and to validate the mod

  17. Computational Chemistry Studies on the Carbene Hydroxymethylene (United States)

    Marzzacco, Charles J.; Baum, J. Clayton


    A density functional theory computational chemistry exercise on the structure and vibrational spectrum of the carbene hydroxymethylene is presented. The potential energy curve for the decomposition reaction of the carbene to formaldehyde and the geometry of the transition state are explored. The results are in good agreement with recent…

  18. Computer-Mediated Communication: An Experimental Study. (United States)

    Smith, William E.


    Investigates the effectiveness of a computer-mediated communication system in supplementing traditional instruction in a media law course. Finds mixed results on measures of satisfaction and no significant improvement on exam scores. Notes that the system required more time from the instructor and students. (SR)

  19. Biomedical Visual Computing: Case Studies and Challenges

    KAUST Repository

    Johnson, Christopher


    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.

  20. Resin Matrix/Fiber Reinforced Composite Material, Ⅱ: Method of Solution and Computer Code

    Institute of Scientific and Technical Information of China (English)

    Li Chensha(李辰砂); Jiao Caishan; Liu Ying; Wang Zhengping; Wang Hongjie; Cao Maosheng


    According to a mathematical model which describes the curing process of composites constructed from continuous fiber-reinforced, thermosetting resin matrix prepreg materials, and the consolidation of the composites, the solution method to the model is made and a computer code is developed, which for flat-plate composites cured by a specified cure cycle, provides the variation of temperature distribution, the cure reaction process in the resin, the resin flow and fibers stress inside the composite, the void variation and the residual stress distribution.

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

    CERN Document Server


    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...

  2. A computational study of alternate SELEX. (United States)

    Seo, Yeon-Jung; Nilsen-Hamilton, Marit; Levine, Howard A


    Systematic evolution of ligands by exponential enrichment (SELEX) is a procedure for identifying nucleic acid (NA) molecules with affinities for specific target species, such as proteins, peptides, or small organic molecules. Here, we extend the work in Seo et al. (Bull Math Biol 72:1623-1665, 2010) (multiple-target SELEX or positive SELEX) and examine an alternate SELEX process with multiple targets by incorporating negative selection into a positive SELEX protocol. The alternate SELEX process is done iteratively by alternating several positive selection rounds with several negative selection rounds. At the end of each positive selection round, NAs are eluted from the bound product and amplified by polymerase chain reaction (PCR) to increase the size of the pool of NA species that bind preferentially to the given positive target vector. The enriched population of NAs is then exposed to the negative targets (undesired targets). The free NA species (instead of the bound NA species being eluted) are retained and amplified by PCR (negative selection). The goal is to minimize an enrichment of nonspecifically binding NAs against multiple targets. While positive selection alone results in a pool of NAs that bind tightly to a given target vector, negative selection results in the subset of the NAs that bind best to the nontarget vectors that are also present. By alternating the two processes, we eventually obtain a refined population of nucleic acids that bind to the desired target(s) with high "selectivity" and "specificity." In the present paper, we give formulations of the negative and alternate selection processes and define their efficiencies in a meaningful way. We study the asymptotic behavior of alternate SELEX system as a discrete-time dynamical system. To do this, we use the chemical potential to examine how alternate SELEX leads to the selection of NAs with more specific interactions when the ratio of the number of positive selection rounds to the number of

  3. 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


    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.


    Directory of Open Access Journals (Sweden)



    Full Text Available The emerging trend of cloud computing that delivers the computing as a service rather than a product whereby shared resources software and information that are provided to computers and other devices asthe utility over the network. Cloud computing model is composed of three service models Software as a Service (SaaS, Platform as a Service (PaaS and Infrastructure as a Service (IaaS and four deployment models Public, Private, Hybrid/mixed. In this paper Cloud computing system that consist of inter- connected computers and virtualized computers that are dynamically provisioned and presented as one or more unified computing resources based on service-level agreements established through negotiation between the service provider and consumers. The introduction of hardware monitoring and software management that was proved to be effective tools for managing the data centers at different locations. This paper further deal with comparative study of data centre challenges of different cloud vendors.

  5. Computational studies of origins of life scenarios (United States)

    Mathew, Damien Cherian

    Understanding the origins of life on Earth is one of the most intriguing problems facing science today. In the research presented here, we apply computational methods to explore origins of life scenarios. In particular, we focus on the origins of the genetic code and the intersection between geochemistry and a primordial "biochemistry" in which mononucleotides could form short oligoucleotide chains. We also apply quantum chemical methods to a modern biochemical reaction, the charging of tRNA by an aminoacyl-tRNA synthetase, in order to shed light on the possible chemistry one may want to consider in problems relating to the origins of life. The question of how codons came to be associated with specific amino acids in the present form of the genetic code is one fundamental part of gaining insight into the origins of life. Carl Woese and coworkers designed a series of experiments to test associations between amino acids and nucleobases that may have played a role in establishing the genetic code. Through these experiments it was found that a property of amino acids called the polar requirement (PR) is correlated to the organization of the codon table. No other property of amino acids has been found that correlates with the codon table as well as PR, indicating that PR is uniquely related to the modern genetic code. Using molecular dynamics simulations of amino acids in solutions of water and dimethylpyridine used to experimentally measure PR, we show that variations in the partitioning between the two phases as described by radial distribution functions correlate well with the measured PRs. Partition coefficients based on probability densities of the amino acids in each phase have the linear behavior with base concentration as suggested by the PR experiments. We also investigate the possible roles of inorganic mineral surfaces in catalysis and stabilization of reactions essential for early forms of replicating systems that could have evolved into biochemical

  6. Computational survey of representative energetic materials as propellants for microthruster applications (United States)

    Fuchs, Brian; Stec, Daniel, III


    Microthrusters are critical for the development of terrestrial micromissiles and nano air vehicles for reconnaissance, surveillance, and sensor emplacement. With the maturation of MEMS manufacturing technology, the physical components of the thrusters can be readily fabricated. The thruster type that is the most straightforward is chemical combustion of a propellant that is ignited by a heating element giving a single shot thrust. Arrays of MEMS manufactured thrusters can be ganged to give multiple firings. The basic model for such a system is a solid rocket motor. The desired elements for the propellant of a chemical thruster are high specific impulse (I sp), high temperature and pressure, and low molecular weight combustion gases. Since the combustion chamber of a microthruster is extremely small, the propellant material must be able to ignite, sustain and complete its burn inside the chamber. The propellant can be either a solid or a liquid. There are a large number of energetic materials available as candidates for a propellant for microthrusters. There has been no systematic evaluation of the available energetic materials as propellant candidates for microthrusters. This report summarizes computations done on a series of energetic materials to address their suitabilities as microthruster propellants.

  7. Fusion Material Studies Relating to Safety in Russia in 2002

    Institute of Scientific and Technical Information of China (English)

    B. N. Kolbasov; M. I. Guseva; B. I. Khripunov; Y. V. Martynenko; P. V. Romanov; S. A. Lelekhov; S. A. Bartenev


    The paper is a summary of Russian material studies performed in frames of activities aiming at substantiation of safety of the International Thermonuclear Experimental Reactor (ITER) after 2001. Subthreshold sputtering of tungsten by 5eV deuterons was revealed at temperatures above 1150rm oC. Mechanism of globular films formation was further studied. Computations of tritium permeation into vacuum vessel coolant confirmed the acceptability of vacuum vessel cooling system for removal of the decay heat. The most dangerous accident with high-current arc in toroidal superconducting magnets able to burn out a bore up to 0.6 m in diameter in the cryostat vessel was determined. Radiochemical reprocessing of V-Cr-Ti alloy and its purification from activation products down to a contact dose rate of ~10muSv/h was developed.

  8. 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


    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

  9. FMR study of thin film FeGe skyrmionic material (United States)

    Bhallamudi, Vidya P.; Page, Michael R.; Gallagher, James; Purser, Carola; Schulze, Joseph; Yang, Fengyuan; Hammel, P. Chris

    Magnetic Skyrmions have attracted intense interest due to their novel topological properties and the potential for energy efficient computing. Magnetic dynamics play an important part in enabling some of these functionalities. Understanding these dynamics can shed light on the interplay of the various magnetic interactions that exist in these materials and lead to a rich magnetic phase diagram, including the Skyrmion phase. We have grown phase-pure FeGe epitaxial films on Si (111) and studied them using ferromagnetic resonance (FMR). FeGe has one of the highest recorded skyrmion transition temperatures, close to room temperature, and thin films are known to further stabilize the Skyrmion phase in the magnetic field-temperature space. We have performed cavity-based single frequency FMR from liquid nitrogen to room temperature on 120 nm thick films in both in-plane and out-of-plane geometries. The resulting complex spectra are consistent with those reported in literature for the bulk material and can be understood in terms of a conical model for the magnetism. Variable temperature broadband spectroscopy and measurements on thinner films, to better identify the various magnetic phases and their dynamic behavior, are ongoing and their progress will be discussed. Funding for this research was provided by the Center for Emergent Materials: an NSF MRSEC under Award Number DMR-1420451.

  10. Computational Studies in Molecular Geochemistry and Biogeochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Felmy, Andrew R.; Bylaska, Eric J.; Dixon, David A.; Dupuis, Michel; Halley, James W.; Kawai, R.; Rosso, Kevin M.; Rustad, James R.; Smith, Paul E.; Straatsma, TP; Voth, Gregory A.; Weare, John H.; Yuen, David A.


    The ability to predict the transport and transformations of contaminants within the subsurface is critical for decisions on virtually every waste disposal option facing the Department of Energy (DOE), from remediation technologies such as in situ bioremediation to evaluations of the safety of nuclear waste repositories. With this fact in mind, the DOE has recently sponsored a series of workshops on the development of a Strategic Simulation Plan on applications of high perform-ance computing to national problems of significance to the DOE. One of the areas selected for application was in the area of subsurface transport and environmental chemistry. Within the SSP on subsurface transport and environmental chemistry several areas were identified where applications of high performance computing could potentially significantly advance our knowledge of contaminant fate and transport. Within each of these areas molecular level simulations were specifically identified as a key capability necessary for the development of a fundamental mechanistic understanding of complex biogeochemical processes. This effort consists of a series of specific molecular level simulations and program development in four key areas of geochemistry/biogeochemistry (i.e., aqueous hydrolysis, redox chemistry, mineral surface interactions, and microbial surface properties). By addressing these four differ-ent, but computationally related, areas it becomes possible to assemble a team of investigators with the necessary expertise in high performance computing, molecular simulation, and geochemistry/biogeochemistry to make significant progress in each area. The specific targeted geochemical/biogeochemical issues include: Microbial surface mediated processes: the effects of lipopolysacchardies present on gram-negative bacteria. Environmental redox chemistry: Dechlorination pathways of carbon tetrachloride and other polychlorinated compounds in the subsurface. Mineral surface interactions: Describing

  11. Multimillion atom simulation of materials on parallel computers — nanopixel, interfacial fracture, nanoindentation, and oxidation (United States)

    Vashishta, Priya; Bachlechner, Martina; Nakano, Aiichiro; Campbell, Timothy J.; Kalia, Rajiv K.; Kodiyalam, Sanjay; Ogata, Shuji; Shimojo, Fuyuki; Walsh, Phillip


    We have developed scalable space-time multiresolution algorithms to enable molecular dynamics simulations involving up to a billion atoms on massively parallel computers. Large-scale molecular dynamics simulations have been used to study stress domains and interfacial fracture in semiconductor/dielectric nanopixels, nanoindentation, and oxidation of metallic nanoparticles.

  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)


    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. Artifacts in magnetic resonance imaging and computed tomography caused by dental materials.

    Directory of Open Access Journals (Sweden)

    Thomas Klinke

    Full Text Available BACKGROUND: Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images. METHODS: Test samples of 44 materials (Metal and Non-Metal commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software. RESULTS: In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact. SIGNIFICANCE: Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images.

  14. Calorimetric and computational study of 7-hydroxycoumarin

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Clara C.S. [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Matos, M. Agostinha R., E-mail: [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Morais, Victor M.F., E-mail: [Centro de Investigacao em Quimica, Departamento de Quimica e Bioquimica, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal); Instituto de Ciencias Biomedicas Abel Salazar, ICBAS, Universidade do Porto, P-4099-003 Porto (Portugal)


    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{sup 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{sup -1}. The values for the temperature of fusion, T{sub fusion}, and for the fusion enthalpy, at T = T{sub 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.

  15. Evaluation of effective thermal diffusivity and conductivity of fibrous materials through computational micromechanics (United States)

    Ahmadi, Isa


    The aim of present study is to investigate the effective thermal properties of composite material via micromechanical modeling of the composite material as a heterogeneous material. These properties mainly include the thermal diffusivity and the thermal conductivity of composites. For this purpose, a definition is presented for effective thermal diffusivity for heterogeneous materials based on heat diffusion rate into the material in a transient heat transfer. A micromechanical model based on the Representative Volume Element (RVE) is presented for modeling the heat conduction in the fibrous composite materials. An appropriate heat transfer problem for the RVE is defined so that by the analogy of the numerical results the effective properties of the RVE can be estimated. A numerical method is employed to analyze the steady-state and transient heat flux and temperature in the RVE. To validate the model, the predictions of present model are compared with results of analytical method, FEM and some available experimental data in the open literature. The effective thermal conductivity and thermal diffusivity are then obtained for fibrous composites via the present micromechanical model. The SiC/Ti, SiC/Ti6%Al4%V and Glass/Epoxy composites with various fiber volume fractions are considered in this study.

  16. Computational Studies of Lobed Forced Mixer Flows

    Institute of Scientific and Technical Information of China (English)

    H.Hu; S.C.M.Yu; 等


    Full Navier-Stokes Analyses have been conducted for the flows behind the trailing edge of a lobed forced mixer,The governing equations are derived from the time-dependent compressible Navier-Stokes equations and discretized in the finite-difference form.A simple two-layer eddy viscosity model has also been used to account for the turbulence.Computed results are compared with some of the velocity measurements using a laser-Doppler anemomter(Yu and Yip (1997),In General,good agreement can be obtained in the streamwise mean velocity distribution but the decay of the streamwise circulation is underpredicted.Some suggestions to the discrepancy are proposed.

  17. Computational and experimental study of laminar flames

    Energy Technology Data Exchange (ETDEWEB)

    Smooke, Mitchell [Yale Univ., New Haven, CT (United States)


    During the past three years, our research has centered on an investigation of the effects of complex chemistry and detailed transport on the structure and extinction of hydrocarbon flames in coflowing axisymmetric configurations. We have pursued both computational and experimental aspects of the research in parallel on both steady-state and time-dependent systems. The computational work has focused on the application of accurate and efficient numerical methods for the solution of the steady-state and time-dependent boundary value problems describing the various reacting systems. Detailed experimental measurements were performed on axisymmetric coflow flames using two-dimensional imaging techniques. Previously, spontaneous Raman scattering, chemiluminescence, and laser-induced fluorescence were used to measure the temperature, major and minor species profiles. Particle image velocimetry (PIV) has been used to investigate velocity distributions and for calibration of time-varying flames. Laser-induced incandescence (LII) with an extinction calibration was used to determine soot volume fractions, while soot surface temperatures were measured with three-color optical pyrometry using a color digital camera. A blackbody calibration of the camera allows for determination of soot volume fraction as well, which can be compared with the LII measurements. More recently, we have concentrated on a detailed characterization of soot using a variety of techniques including time-resolved LII (TiRe-LII) for soot primary particles sizes, multi-angle light scattering (MALS) for soot radius of gyration, and spectrally-resolved line of sight attenuation (spec-LOSA). Combining the information from all of these soot measurements can be used to determine the soot optical properties, which are observed to vary significantly depending on spatial location and fuel dilution. Our goal has been to obtain a more fundamental understanding of the important fluid dynamic and chemical interactions in

  18. Preferred computer activities among individuals with dementia: a pilot study. (United States)

    Tak, Sunghee H; Zhang, Hongmei; Hong, Song Hee


    Computers offer new activities that are easily accessible, cognitively stimulating, and enjoyable for individuals with dementia. The current descriptive study examined preferred computer activities among nursing home residents with different severity levels of dementia. A secondary data analysis was conducted using activity observation logs from 15 study participants with dementia (severe = 115 logs, moderate = 234 logs, and mild = 124 logs) who participated in a computer activity program. Significant differences existed in preferred computer activities among groups with different severity levels of dementia. Participants with severe dementia spent significantly more time watching slide shows with music than those with both mild and moderate dementia (F [2,12] = 9.72, p = 0.003). Preference in playing games also differed significantly across the three groups. It is critical to consider individuals' interests and functional abilities when computer activities are provided for individuals with dementia. A practice guideline for tailoring computer activities is detailed.

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

    Directory of Open Access Journals (Sweden)

    Derek Lavelle


    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.

  20. 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


    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.

  1. Tribological Studies of Dynamic Thermal Seal Materials (United States)

    DeMange, Jeffrey J.; Taylor, Shawn C.


    Thermal seals are required on high-speed vehicles in many dynamic applications such as variable inlets in propulsion systems and control surfaces. These seals, often referred to as dynamic thermal seals, must not only mitigate inboard heat transfer, but must also exhibit sufficient durability when scrubbed against mating surfaces. For high-temperature high-speed vehicle applications, the mating surfaces are often made from thermal protection system (TPS) materials, which are typically rougher and more abrasive than TPS materials used at lower temperatures. The high-temperature TPS materials used can include non-ablative (e.g., lightweight porous oxides, ceramic matrix composites) andor ablative systems (e.g., phenolic systems). Due to the increased need for durable high-temperature dynamic seals, researchers working with the NASA Glenn Research Center embarked on an effort to (a) characterize the tribological performance of state-of-the-art thermal seal materials against a variety of TPS materials and (b) develop approaches for improved wear resistance. Tests were conducted using a recently upgraded high-temperature tribometer to assess wear resistance for a variety of tribopairs under multiple conditions. This data will begin to frame the challenges of using these materials and eventually permit an improved ability to design and implement these critical TPS components.

  2. Parents' Regulation and Self-Regulation and Performance in Children with Intellectual Disability in Problem-Solving Using Physical Materials or Computers (United States)

    Nader-Grosbois, Nathalie; Lefevre, Nathalie


    This study compared mothers and fathers' regulation with respect to 29 children with intellectual disability (ID) and 30 typically developing (TD) children, matched on their mental age (MA), as they solved eight tasks using physical materials and computers. Seven parents' regulatory strategies were coded as they supported their child's…

  3. Study of New Materials Design based on Hadoop

    Directory of Open Access Journals (Sweden)

    Wu Jun


    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.

  4. 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: [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)


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    King, W. E., E-mail: [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)


    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.

  6. On the role of solidification modelling in Integrated Computational Materials Engineering “ICME” (United States)

    Schmitz, G. J.; Böttger, B.; Apel, M.


    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.

  7. Demonstration of Emitted-Neutron Computed Tomography to Quantify Nuclear Materials

    Energy Technology Data Exchange (ETDEWEB)

    Hausladen, Paul [ORNL; Blackston, Matthew A [ORNL; Newby, Jason [ORNL


    In this document, we report demonstration of emitted-neutron computed tomography using fast fission neutrons to infer the geometry of sources of special nuclear material (SNM). The imaging system employed in the demonstration is based on a newly constructed array of pixelated neutron detectors that are suitable for arrangement in a close-packed imaging array and whose active volume consists of liquid scintillator EJ-309 which allows neutron-gamma discrimination via pulse shape to enable essentially pure fast-neutron imaging. The system is capable of high quality fast-neutron imaging where tomographic reconstruction of slices through an object resolves neutron sources similar in dimension to a fuel pellet, or about 1 cm. During measurements of Pu MOX fuel rodlet arrays in soup cans at the INL ZPPR facility, the position of a partial defect of a single rodlet containing Pu replaced by one containing depleted uranium (DU) was detected.

  8. Logic computation in phase change materials by threshold and memory switching. (United States)

    Cassinerio, M; Ciocchini, N; Ielmini, D


    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.

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

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


    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. Design Principles for Computer-Assisted Instruction in Histology Education: An Exploratory Study (United States)

    Deniz, Hasan; Cakir, Hasan


    The purpose of this paper is to describe the development process and the key components of a computer-assisted histology material. Computer-assisted histology material is designed to supplement traditional histology education in a large Midwestern university. Usability information of the computer-assisted instruction (CAI) material was obtained…

  11. Process Simulation Role in the Development of New Alloys Based on Integrated Computational Material Science and Engineering

    Energy Technology Data Exchange (ETDEWEB)

    Sabau, Adrian S [ORNL; Porter, Wallace D [ORNL; Roy, Shibayan [ORNL; Shyam, Amit [ORNL


    To accelerate the introduction of new materials and components, the development of metal casting processes requires the teaming between different disciplines, as multi-physical phenomena have to be considered simultaneously for the process design and optimization of mechanical properties. The required models for physical phenomena as well as their validation status for metal casting are reviewed. The data on materials properties, model validation, and relevant microstructure for materials properties are highlighted. One vehicle to accelerate the development of new materials is through combined experimental-computational efforts. Integrated computational/experimental practices are reviewed; strengths and weaknesses are identified with respect to metal casting processes. Specifically, the examples are given for the knowledge base established at Oak Ridge National Laboratory and computer models for predicting casting defects and microstructure distribution in aluminum alloy components.

  12. Computational studies of quantum dot sensitized solar cells (United States)

    Kolesov, Grigory

    This thesis presents a computational study of quantum dot (QD) sensitized solar cells. First part deals with the non-equilibrium many-body theory or non-equilibrium Green's function (NEGF) theory. In this approach I study electron dynamics in the quantum-dot sensitized solar cell subjected to time-dependent fields. NEGF theory, because it does not impose any conditions on a perturbation, is the fundamental one to describe ultrafast processes in small, strongly correlated systems and/or in strong fields. In this research I do not only perform analytical derivation, but also design and implement spectral numerical solution for the resulting complex system of partial integrodifferential equations. This numerical solution yielded an order of magnitude speedup over the methods used previously in the field. The forth chapter of this thesis deals with calculation of optical properties and the ground state configuration of Zn2SnO4 (ZTO). ZTO is used by experimentalists in UW to grow nanorods which are then sensitized by QDs. ZTO is a challenging material for computational analysis because of its inverse spinel structure; thus it has an immense number of configurations matching the X-ray diffraction experiments. I've applied a cluster expansion method and have found the ground state configuration and phase diagram for ZTO. Calculations of optical properties of ground state bulk ZTO were done with a recently developed DFT functional. The optical band gap obtained in these calculations matched the experimental value. The last chapter describes development of the general simulator for interdigitated array electrodes. The application of this simulation together with the experiments may lead to understanding of reaction parameters and mechanisms important for development of electrochemical solar cells.

  13. 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)


    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.

  14. Studying an Eulerian Computer Model on Different High-performance Computer Platforms and Some Applications (United States)

    Georgiev, K.; Zlatev, Z.


    The Danish Eulerian Model (DEM) is an Eulerian model for studying the transport of air pollutants on large scale. Originally, the model was developed at the National Environmental Research Institute of Denmark. The model computational domain covers Europe and some neighbour parts belong to the Atlantic Ocean, Asia and Africa. If DEM model is to be applied by using fine grids, then its discretization leads to a huge computational problem. This implies that such a model as DEM must be run only on high-performance computer architectures. The implementation and tuning of such a complex large-scale model on each different computer is a non-trivial task. Here, some comparison results of running of this model on different kind of vector (CRAY C92A, Fujitsu, etc.), parallel computers with distributed memory (IBM SP, CRAY T3E, Beowulf clusters, Macintosh G4 clusters, etc.), parallel computers with shared memory (SGI Origin, SUN, etc.) and parallel computers with two levels of parallelism (IBM SMP, IBM BlueGene/P, clusters of multiprocessor nodes, etc.) will be presented. The main idea in the parallel version of DEM is domain partitioning approach. Discussions according to the effective use of the cache and hierarchical memories of the modern computers as well as the performance, speed-ups and efficiency achieved will be done. The parallel code of DEM, created by using MPI standard library, appears to be highly portable and shows good efficiency and scalability on different kind of vector and parallel computers. Some important applications of the computer model output are presented in short.

  15. Design and Development Computer-Based E-Learning Teaching Material for Improving Mathematical Understanding Ability and Spatial Sense of Junior High School Students (United States)

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


    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.

  16. A Case Study: Novel Group Interactions through Introductory Computational Physics

    CERN Document Server

    Obsniuk, Michael J; Caballero, Marcos D


    With the advent of high-level programming languages capable of quickly rendering three-dimensional simulations, the inclusion of computers as a learning tool in the classroom has become more prevalent. Although work has begun to study the patterns seen in implementing and assessing computation in introductory physics, more insight is needed to understand the observed effects of blending computation with physics in a group setting. In a newly adopted format of introductory calculus-based mechanics, called Projects and Practices in Physics, groups of students work on short modeling projects -- which make use of a novel inquiry-based approach -- to develop their understanding of both physics content and practice. Preliminary analyses of observational data of groups engaging with computation, coupled with synchronized computer screencast, has revealed a unique group interaction afforded by the practices specific to computational physics -- problem debugging.

  17. 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.


    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

  18. Text, Graphics, and Multimedia Materials Employed in Learning a Computer-Based Procedural Task (United States)

    Coffindaffer, Kari Christine Carlson


    The present research study investigated the interaction of graphic design students with different forms of software training materials. Four versions of the procedural task instructions were developed (A) Traditional Textbook with Still Images, (B) Modified Text with Integrated Still Images, (C) Onscreen Modified Text with Silent Onscreen Video…

  19. An Exploratory Study of Apache Middle School Students' Computer Animation. (United States)

    Stokrocki, Mary; Buckpitt, Marcia

    The paper describes a participant observation study of a 3 week summer art program for Apache middle school students on the White Mountain Reservation. Computer art skills, specifically animation using a menu-driven computer paint program, were the focus of the investigation. Because it was in the context of a summer program, instruction was…

  20. Study Guide in Digital Computing and Related Mathematics. (United States)

    Stanford Univ., CA. School Mathematics Study Group.

    This SMSG study guide is designed to aid the teacher in acquiring familiarity with digital computer concepts or to further his/her knowledge of the field. Suitable references for important topics are categorized as central, peripheral, or advanced. Topics covered include: (1) nature and organization of computers; (2) problem analysis; (3)…

  1. 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.


    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.

  2. 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


    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.

  3. Using symbolic computation in the characterization of frictional instabilities involving orthotropic materials

    Directory of Open Access Journals (Sweden)

    Agwa Mohamed A.


    Full Text Available The present work addresses the problem of determining under what conditions the impending slip state or the steady sliding of a linear elastic orthotropic layer or half space with respect to a rigid flat obstacle is dynamically unstable. In other words, we search the conditions for the occurrence of smooth exponentially growing dynamic solutions with perturbed initial conditions arbitrarily close to the steady sliding state, taking the system away from the equilibrium state or the steady sliding state. Previously authors have shown that a linear elastic isotropic half space compressed against and sliding with respect to a rigid flat surface may get unstable by flutter when the coefficient of friction μ and Poisson’s ratio ν are sufficiently large. In the isotropic case they have been able to derive closed form analytic expressions for the exponentially growing unstable solutions as well as for the borders of the stability regions in the space of parameters, because in the isotropic case there are only two dimensionless parameters (μ and ν. Already for the simplest version of orthotropy (an orthotropic transversally isotropic material there are seven governing parameters (μ, five independent material constants and the orientation of the principal directions of orthotropy and the expressions become very lengthy and literally impossible to manipulate manually. The orthotropic case addressed here is impossible to solve with simple closed form expressions, and therefore the use of computer algebra software is required, the main commands being indicated in the text.

  4. 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)


    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

  5. Study on Fuels and Materials of Reactor

    Institute of Scientific and Technical Information of China (English)


    2.1 Effect of N+ Ions Implanted on Electrochemical Property of 316 s.s.,Super-pure Aluminium and 6061 Aluminium Alloy Ma Yan Lu Haolin Yang Qifa Yang Hongguang 316 s.s., super-pure aluminium and 6061 aluminium alloy are three materials widely used in engineering. For improving some of their mechanical properties, such as self-welding, friction and fretting resistence properties, surface processing is employed sometimes, for example, ion implantation, thermal spray coating, nitridation. Ion implantation is an advanced method of material surface treatment. This report describes the effect of corrosion resistance on three materials above mentioned by N+ ions implanted. Firstly, the samples were implanted with 160 keV N+ ion and the total dose was 15×1017 cm-2. The method of controled voltage was used to measure the electrochemical property. The corrosive medium was 0.5 mol·L-1 H2SO4 and reference electrode was calomel electrode. The anodic polarization curves of materials implanted and unimplanted were obtained by Model 350A corrosion measuring instrument(Fig. 1, 2,3).

  6. Micromechanical study of plasticity of granular materials

    NARCIS (Netherlands)

    Kruyt, N.P.


    Plastic deformation of granular materials is investigated from the micromechanical viewpoint, in which the assembly of particles and interparticle contacts is considered as a mechanical structure. This is done in three ways. Firstly, by investigating the degree of redundancy of the system by compari

  7. Methods for Studying Tank Armament Materials. (United States)

    Rogov, I. V.

    This translation from the Russian contains discussions on the most expedient sequence for presenting problems in firing training for military tank crews, methods of learning, and the practices and actions which can be recommended to training supervisors. The document is an attempt to summarize and systematize materials; it also presents advice and…

  8. Study of biocompatible and biological materials

    CERN Document Server

    Pecheva, Emilia


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Devanathan, Ram


    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

  10. Realization of prediction of materials properties by ab initio computer simulation

    Indian Academy of Sciences (India)

    Yoshiyuki Kawazoe


    Ab initio treatment is becoming realistic to predict physical, chemical, and even mechanical properties of academically and industrially interesting materials. There is, however, some limitation in size and time of the system up to the order of several hundred atoms and ∼ 1 pico second, even if we use the fastest supercomputer efficiently. Therefore, it is very difficult to simulate realistic materials with grain boundaries and important reactions like diffusion in materials. To improve this situation, two ways have been invented. One way is to upgrade approximations to match the necessary levels according to inhomogeneous electron gas theory beyond the present day standard, i.e. local density approximation (LDA). The reason is simply that the system we are interested in is composed of many particles interacting with Coulomb forces governed by quantum mechanics. (Complete knowledge is available, and only what we should do is to make better approximations to explain the phenomena!). Another is to extract the necessary parameters from the ab initio calculations on systems with limited number of atoms, and apply these results into cluster variation, direct, or any other sophisticated methods based on classical concepts such as statistical mechanics. In this paper, several typical examples recently worked out by our research group are introduced to indicate that these methodologies are actually possible to be successfully used to predict materials properties before experiments based on the present day state-of-art supercomputing systems. It includes scientific visualization of the results of ab initio molecular dynamics simulation on atom insertion process to C60 and to carbon nanotube, tight-binding calculation of single electron conductance properties in nanotube to create nano-scale diode virtually by computer, which will be a base of future nanoscale electric device in nanometer size, Li + H reaction without Born–Oppenheimer approximation, structural phase

  11. Studies in Mathematics, Volume 22. Studies in Computer Science. (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…

  12. Computer Science and Engineering Students Addressing Critical Issues Regarding Gender Differences in Computing: a Case Study

    Directory of Open Access Journals (Sweden)

    Evrikleia Tsagala


    Full Text Available This study focuses on how Computer Science and Engineering Students (CSESs of both genders address certain critical issues for gender differences in the field of Computer Science and Engineering (CSE. This case study is based on research conducted on a sample of 99 Greek CSESs, 43 of which were women. More specifically, these students were asked to respond to a specially designed questionnaire addressing the following issues: a essential motives in selecting CSE as a subject of study, their primary experience with computers and their family’s views regarding CSE as a career prospect, b the relationship between gender, strengths and weaknesses in CSE and cooperation with fellow students of the opposite gender, c the desirability of having both male and female University Professors in CSE, d CSE courses and CSESschoice, and e career issues. The analysis of the data shows that: a gender inequality in CSE still exists at tertiary level, b there is a number of students of both genders who feel interest and self confident in CSE, they believe in equality in competence of both genders in CSE and have dreams of a job with prospects as computer professionals, c interest, self confidence in CSE are closely related to previous experience with computers and to the encouragement byfamily and school to learn about computers, and d the general atmosphere and policy in CSE Departments play an essential role for women-students to feel as equals to their male counterparts.

  13. Experimental and computational analysis of micromotions of an uncemented femoral knee implant using elastic and plastic bone material models. (United States)

    Berahmani, Sanaz; Janssen, Dennis; Verdonschot, Nico


    It is essential to calculate micromotions at the bone-implant interface of an uncemented femoral total knee replacement (TKR) using a reliable computational model. In the current study, experimental measurements of micromotions were compared with predicted micromotions by Finite Element Analysis (FEA) using two bone material models: linear elastic and post-yield material behavior, while an actual range of interference fit was simulated. The primary aim was to investigate whether a plasticity model is essential in order to calculate realistic micromotions. Additionally, experimental bone damage at the interface was compared with the FEA simulated range. TKR surgical cuts were applied to five cadaveric femora and micro- and clinical CT- scans of these un-implanted specimens were made to extract geometrical and material properties, respectively. Micromotions at the interface were measured using digital image correlation. Cadaver-specific FEA models were created based on the experimental set-up. The average experimental micromotion of all specimens was 53.1±42.3µm (mean±standard deviation (SD)), which was significantly higher than the micromotions predicted by both models, using either the plastic or elastic material model (26.5±23.9µm and 10.1±10.1µm, respectively; p-valuematerial models). The difference between the two material models was also significant (p-value<0.001). The predicted damage had a magnitude and distribution which was comparable to the experimental bone damage. We conclude that, although the plastic model could not fully predict the micro motions, it is more suitable for pre-clinical assessment of a press-fit TKR implant than using an elastic bone model. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. New resource for the computation of cartilage biphasic material properties with the interpolant response surface method. (United States)

    Keenan, Kathryn E; Kourtis, Lampros C; Besier, Thor F; Lindsey, Derek P; Gold, Garry E; Delp, Scott L; Beaupre, Gary S


    Cartilage material properties are important for understanding joint function and diseases, but can be challenging to obtain. Three biphasic material properties (aggregate modulus, Poisson's ratio and permeability) can be determined using an analytical or finite element model combined with optimisation to find the material properties values that best reproduce an experimental creep curve. The purpose of this study was to develop an easy-to-use resource to determine biphasic cartilage material properties. A Cartilage Interpolant Response Surface was generated from interpolation of finite element simulations of creep indentation tests. Creep indentation tests were performed on five sites across a tibial plateau. A least-squares residual search of the Cartilage Interpolant Response Surface resulted in a best-fit curve for each experimental condition with corresponding material properties. These sites provided a representative range of aggregate moduli (0.48-1.58 MPa), Poisson's ratio (0.00-0.05) and permeability (1.7 x 10(- 15)-5.4 x 10(- 15) m(4)/N s) values found in human cartilage. The resource is freely available from

  15. A twin study of computer anxiety in Turkish adolescents. (United States)

    Deryakulu, Deniz; Calışkan, Erkan


    The present study investigated computer anxiety within a sample of Turkish twins aged 10-18. A total of 185 twin-pairs participated in the study. Of the twins, 64 pairs (34.6 percent) were monozygotic (MZ) and 121 pairs (65.4 percent) were dizygotic (DZ). Of the 121 DZ twins, 54 pairs (44.63 percent) were same-sex twins and 67 pairs (55.37 percent) were opposite-sex twins. Computer anxiety was assessed using Computer Anxiety Rating Scale-Turkish Version (CARS-TV), one of the three main scales of "Measuring Technophobia Instruments" developed by Rosen and Weil. The results of paired t test comparisons showed no significant differences in MZ and same-sex DZ twin-pairs' levels of computer anxiety. On the other hand, a significant difference was found in opposite-sex DZ twin-pairs' level of computer anxiety. Interesting enough, males appeared to be more computer anxious than their female co-twins. In the present study, using Falconer's formula, heritability estimate for computer anxiety was derived from correlations based on MZ and DZ twins' mean scores on CARS-TV. The results showed that 57 percent of the variance in computer anxiety was from genetics and 41.5 percent was from nonshared environmental factors. Shared environmental influence, on the other hand, was very small and negligible. Interpretations of results and potential directions for future research are presented.

  16. Educational NASA Computational and Scientific Studies (enCOMPASS) (United States)

    Memarsadeghi, Nargess


    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 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

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

    African Journals Online (AJOL)

    Fluoride removal studies in water using natural materials : technical note. ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL ... The removal of fluoride was attempted using natural materials such as red soil, ...

  18. Material length scales in gradient-dependent plasticity/damage and size effects: Theory and computation (United States)

    Abu Al-Rub, Rashid Kamel

    Structural materials display a strong size-dependence when deformed non-uniformly into the inelastic range: smaller is stronger. This effect has important implications for an increasing number of applications in structural failure, electronics, functional coatings, composites, micro-electro-mechanical systems (MEMS), nanostructured materials, micro/nanometer fabrication technologies, etc. The mechanical behavior of these applications cannot be characterized by classical (local) continuum theories because they incorporate no, 'material length scales' and consequently predict no size effects. On the other hand, it is still not possible to perform quantum and atomistic simulations on realistic time and structures. It is therefore necessary to develop a scale-dependent continuum theory bridging the gap between the classical continuum theories and the atomistic simulations in order to be able to design the size-dependent structures of modern technology. Nonlocal rate-dependent and gradient-dependent theories of plasticity and damage are developed in this work for this purpose. We adopt a multi-scale, hierarchical thermodynamic consistent framework to construct the material constitutive relations for the scale-dependent plasticity/damage behavior. Material length scales are implicitly and explicitly introduced into the governing equations through material rate-dependency (viscosity) and coefficients of spatial higher-order gradients of one or more material state variables, respectively. The proposed framework is implemented into the commercially well-known finite element software ABAQUS. The finite element simulations of material instability problems converge to meaningful results upon further refinement of the finite element mesh, since the width of the fracture process zone (shear band) is determined by the intrinsic material length scale; while the classical continuum theories fail to address this problem. It is also shown that the proposed theory is successful for

  19. Parametric study of silo-material interaction (United States)

    Hasanain, G. S.


    The methods for determination of pressures and the analysis of silos for storage of granular materials are reviewed. A finite element procedure for linear analysis and an initial-strain analysis of hoop forces and horizontal bending moments in circular concrete silos with bisymmetric outlets is presented, and these methods are compared with the hoop steel areas obtained using current practice. A concrete coal silo is designed by these methods and compared with one designed by standard methods.

  20. Plasma characterization studies for materials processing

    Energy Technology Data Exchange (ETDEWEB)

    Pfender, E.; Heberlein, J. [Univ. of Minnesota, Minneapolis, MN (United States)


    New applications for plasma processing of materials require a more detailed understanding of the fundamental processes occurring in the processing reactors. We have developed reactors offering specific advantages for materials processing, and we are using modeling and diagnostic techniques for the characterization of these reactors. The emphasis is in part set by the interest shown by industry pursuing specific plasma processing applications. In this paper we report on the modeling of radio frequency plasma reactors for use in materials synthesis, and on the characterization of the high rate diamond deposition process using liquid precursors. In the radio frequency plasma torch model, the influence of specific design changes such as the location of the excitation coil on the enthalpy flow distribution is investigated for oxygen and air as plasma gases. The diamond deposition with liquid precursors has identified the efficient mass transport in form of liquid droplets into the boundary layer as responsible for high growth, and the chemical properties of the liquid for the film morphology.

  1. Computational Study of Electron Delocalization in Hexaarylbenzenes

    Directory of Open Access Journals (Sweden)

    Citlalli Rios


    Full Text Available A number of hexaarylbenzene compounds were studied theoretically, in order to compare energy changes as a result of the toroidal delocalization effect that is characteristic of all these species. The energy was studied taking advantage of locally designed isodesmic reactions. Results indicate that the amount of aromaticity manifested by each substituent is a factor that should be considered when assessing the quantity of energy dissipated from each aromatic center. The influence of different substituents on electronic delocalization is also analyzed, as well as the role played by their frontier molecular orbitals.

  2. A study of computer-related upper limb discomfort and computer vision syndrome. (United States)

    Sen, A; Richardson, Stanley


    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.

  3. Enrique: A case study of a gifted computer user

    Energy Technology Data Exchange (ETDEWEB)

    Sesko, S C


    The author has been investigating the affective and intellectual views that gifted children have about computers. These studies have used various methodological approaches in order to develop a broad perspective on the issues involved in this topic. The author has used survey instruments (Sesko, 1998) and interview techniques (Sesko, 1999) to capture both statistical and narrative data. The objective of this study is to explore in depth the interactions that one student has with the machine and its applications. The driver for this and the previous studies was the paucity of research in the area of gifted and talented children and their involvement with what has become the primary intellectual tool of the century (Turkel, 1984). The second reason is that it has been posited that the intellectual characteristics of gifted children should enable those who are interested in computers to achieve a high level of proficiency with either computer applications or programming. Further, the ability to learn things at a young age should allow gifted children who use computers to develop a large variety of computer-based activities. The author has shown evidence to support these ideas in previous work. Finally, as Hausman (1985) claims, facilities with computers should allow these children to create new activities for using computers. The author found no published research to demonstrate whether they do; but still believes the results of this case study strongly support Hausman's contentions.

  4. Quantitative material analysis by dual-energy computed tomography for industrial NDT applications (United States)

    Nachtrab, F.; Weis, S.; Keßling, P.; Sukowski, F.; Haßler, U.; Fuchs, T.; Uhlmann, N.; Hanke, R.


    Dual-energy computed tomography (DECT) is an established method in the field of medical CT to obtain quantitative information on a material of interest instead of mean attenuation coefficients only. In the field of industrial X-ray imaging dual-energy techniques have been used to solve special problems on a case-by-case basis rather than as a standard tool. Our goal is to develop an easy-to-use dual-energy solution that can be handled by the average industrial operator without the need for a specialist. We are aiming at providing dual-energy CT as a measurement tool for those cases where qualitative images are not enough and one needs additional quantitative information (e.g. mass density ρ and atomic number Z) about the sample at hand. Our solution is based on an algorithm proposed by Heismann et al. (2003) [1] for application in medical CT . As input data this algorithm needs two CT data sets, one with low (LE) and one with high effective energy (HE). A first order linearization is applied to the raw data, and two volumes are reconstructed thereafter. The dual-energy analysis is done voxel by voxel, using a pre-calculated function F(Z) that implies the parameters of the low and high energy measurement (such as tube voltage, filtration and detector sensitivity). As a result, two volume data sets are obtained, one providing information about the mass density ρ in each voxel, the other providing the effective atomic number Z of the material therein. One main difference between medical and industrial CT is that the range of materials that can be contained in a sample is much wider and can cover the whole range of elements, from hydrogen to uranium. Heismann's algorithm is limited to the range of elements Z=1-30, because for Z>30 the function F(Z) as given by Heismann is not a bijective function anymore. While this still seems very suitable for medical application, it is not enough to cover the complete range of industrial applications. We therefore investigated the

  5. Computational simulation of probabilistic lifetime strength for aerospace materials subjected to high temperature, mechanical fatigue, creep and thermal fatigue (United States)

    Boyce, Lola; Bast, Callie C.; Trimble, Greg A.


    This report presents the results of a fourth year effort of a research program, conducted for NASA-LeRC by the University of Texas at San Antonio (UTSA). The research included on-going 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 subject to a number of effects or primitive variables. These primitive variables 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 regression analysis of that data, thereby predicting values for the empirical material constants for each effect or primitive variable. This regression methodology is included in the computer program, PROMISC. Actual experimental materials data were obtained from industry and the open literature for materials typically for applications in aerospace propulsion system components. Material data for Inconel 718 has been analyzed using the developed methodology.

  6. Osmosis : a molecular dynamics computer simulation study (United States)

    Lion, Thomas

    Osmosis is a phenomenon of critical importance in a variety of processes ranging from the transport of ions across cell membranes and the regulation of blood salt levels by the kidneys to the desalination of water and the production of clean energy using potential osmotic power plants. However, despite its importance and over one hundred years of study, there is an ongoing confusion concerning the nature of the microscopic dynamics of the solvent particles in their transfer across the membrane. In this thesis the microscopic dynamical processes underlying osmotic pressure and concentration gradients are investigated using molecular dynamics (MD) simulations. I first present a new derivation for the local pressure that can be used for determining osmotic pressure gradients. Using this result, the steady-state osmotic pressure is studied in a minimal model for an osmotic system and the steady-state density gradients are explained using a simple mechanistic hopping model for the solvent particles. The simulation setup is then modified, allowing us to explore the timescales involved in the relaxation dynamics of the system in the period preceding the steady state. Further consideration is also given to the relative roles of diffusive and non-diffusive solvent transport in this period. Finally, in a novel modification to the classic osmosis experiment, the solute particles are driven out-of-equilibrium by the input of energy. The effect of this modification on the osmotic pressure and the osmotic ow is studied and we find that active solute particles can cause reverse osmosis to occur. The possibility of defining a new "osmotic effective temperature" is also considered and compared to the results of diffusive and kinetic temperatures..

  7. Computational Studies of Nanostructures of Boron (United States)

    Tandy, P.; Yu, M.; Leahy, C.; Tian, W. Q.; Wu, S. Y.; Jayanthi, C. S.


    The goal of this work is to develop a reliable semi-empirical Hamiltonian for boron that may be used to predict nanostructures of boron. It is well known that bonding in boron is complicated as it may form three-center, two-electron bonds. The semi-empirical Hamiltonian used here was recently developed by Leahy et al. in the framework of linear combination of atomic orbitals[1]. The salient feature of this Hamiltonian is that it treats environment dependency and charge redistributions on equal footing. It will be shown that such a parameterized Hamiltonian can predict the B80 cage structure with C1 symmetry as found in a recent first-principles study [2]. Having validated our semi-empirical Hamiltonian for boron with small boron clusters and the B80 cage, we have performed a systematic study of other boron nanostructures: (i) larger cage structures (e.g., B215), (ii) boron clusters cut from the bulk alpha boron, and (iii) boron sheets (triangular sheets with and without holes). We will discuss the ground state structures of these boron nanostructures as well as the energetics and HOMO-LUMO gaps of different families of boron clusters as a function their diameters. 1. C. Leahy et al. Phys. Rev. B74, 155408 (2006). 2. N. G. Szwacki et al. PRL 100, 159901 (2008).

  8. Capabilities of computer materials science and irradiation experiments for irradiation materials database and design methodology development (based on discussions at the {sup I}EA symposium on fusion reactor materials development)

    Energy Technology Data Exchange (ETDEWEB)

    Jitsukawa, S.; Suzuki, K.; Kaburaki, H. [Japan Atomic Energy Agency, Tokai-mura, Naga-gun, Ibaraki-ken (Japan); Wiffen, F.W.; Stoller, R. [ORNL - Oak Ridge National Laboratory, Materials Science and Technology Div., AK TN (United States); Sharafat, S. [UCLA, Los Angeles, Mechanical and Aerospace Engineering Dept., AK CA (United States)


    Full text of publication follows: Irradiation by high-energy fusion neutrons of the first wall of a DEMO blanket introduces transmutation produced helium atoms and displacement damage in the structural material to levels of greater than 1000 appm and 100 displacement per atom during typical service lifetimes, respectively. To simulate high levels of helium atoms in materials, doping techniques using species with large helium producing cross sections are often used in fission reactor irradiation experiments. However, the capability of these techniques is rather limited due to the geometric accumulation of dopants and helium along grain boundaries. In recent years, significant progress in modeling and simulation studies on these irradiation effects using large-scale computational techniques has been achieved. However, further improvements in accuracy and reliability of modeling results are needed prior to application of these results to structural design analyses and licensing. Therefore, the community is anticipating the construction of an intense neutron source, such as the d-Li stripping reaction neutron source of the International Fusion Materials Irradiation Facility (IFMIF). At the recent 'IEA Symposium on Fusion Reactor Materials Development' held Tokyo, Japan 2006, accomplishments of modeling and simulation studies, results of fission neutron and ion irradiation experiments, and a gap between the knowledge of these activities and design methodology of fusion reactor components were presented and discussed. One of the major conclusions of the meeting was that 'IFMIF is an essential facility in the pursuit of a low-risk path to the rapid development of commercially-viable fusion energy (DEMO). To facilitate highly productive IFMIF and supporting efforts (theory, modeling, and computer materials science), it is also important to enhance the activities of materials development, by continuing irradiation experiments in fission reactors and at other

  9. An Integrative Study on Bioinformatics Computing Concepts, Issues and Problems

    Directory of Open Access Journals (Sweden)

    Muhammad Zakarya


    Full Text Available Bioinformatics is the permutation and mishmash of biological science and 4IT. The discipline covers every computational tools and techniques used to administer, examine and manipulate huge sets of biological statistics. The discipline also helps in creation of databases to store up and supervise biological statistics, improvement of computer algorithms to find out relations in these databases and use of computer tools for the study and understanding of biological information, including DNA, RNA, protein sequences, gene expression profiles, protein structures, and biochemical pathways. The study of this paper implements an integrative solution. As we know that solution to a problem in a specific discipline may be a solution to another problem in a different discipline. For example entropy that has been rented from physical sciences is solution to most of the problems and issues in computer science. Another example is bioinformatics, where computing method and applications are implemented over biological information. This paper shows an initiative step towards that and will discuss upon the needs for integration of multiple discipline and sciences. Similarly green chemistry gives birth to a new kind of computing i.e. green computing. In next versions of this paper we will study biological fuel cell and will discuss to develop a mobile battery that will be life time charged using the concepts of biological fuel cell. Another issue that we are going to discuss in our series is brain tumor detection. This paper is a review on BI i.e. bioinformatics to start with.

  10. Use of Computer among Medical Students: A Cross Sectional Study

    Directory of Open Access Journals (Sweden)

    Siddharth Kumar


    Full Text Available Background: Computer is a part of our daily life. In Medical Science it has become an essential product in every hospital. Starting from open heart surgeries to X rays to various clinical tests all are carried out by the help of computer. They communicate with each other by email, live chatting and they also use to take full advantage of technology. They also use the computer and internet nearly as much for social communication as they do for their educational purposes.Methods: This cross-sectional study was conducted from January to August 2010 at NMC, Birgunj, Nepal. The subjects of this survey were Undergraduate medical students.Results: Most of the students were in the age group of 21- 23yrs and 19 – 20 yrs. Males were more in number (62% compared with females. Among Ist yr students computer as a Source of information got priority but in IInd year students Source of information Preparing notes and reading Research articles were more important. Amusement and Preparing notes and reading Research articles were important factor for IIIrd & IVth Year students.Conclusion: The use of the laptop and personal computers along with internet connectivity is increasing. This is becoming a part of medical education in different parts of the globe. In this study on medical students we observed an association between the year of study and the purpose of computer and internet use. Computer assisted teaching learning activities should be encouraged for the improvement of medical science for the new generations.

  11. A Study of Cloud Computing in the University Enterprise

    Directory of Open Access Journals (Sweden)

    Adigun A. Adebisi


    Full Text Available The demand for computing resources in the university is on the increase on daily basis and the traditional method of acquiring computing resources may no longer meet up with the present demand. This is as a result of high level of researches being carried out by the universities. The 21st century universities are now seen as the centre and base of education, research and development for the society. The university community now has to deal with a large number of people including staff, students and researchers working together on voluminous large amount of data. This actually requires very high computing resources that can only be gotten easily through cloud computing. In this paper, we have taken a close look at exploring the benefits of cloud computing and study the adoption and usage of cloud services in the University Enterprise. We establish a theoretical background to cloud computing and its associated services including rigorous analysis of the latest research on Cloud Computing as an alternative to IT provision, management and security and discuss the benefits of cloud computing in the university enterprise. We also assess the trend of adoption and usage of cloud services in the university enterprise.


    Institute of Scientific and Technical Information of China (English)

    FENG Yongping; CUI Junzhi


    In this paper, the multi-scale computational method for a structure of composite materials with a small periodic configuration under the coupled thermoelasticity condition is presented.The two-scale asymptotic (TSA) expression of the displacement and the increment of temperature for composite materials with a small periodic configuration under the condition of thermoelasticity are briefly shown at first, then the multi-scale finite element algorithms based on TSA are discussed. Finally the numerical results evaluated by the multi-scale computational method are shown. It demonstrates that the basic configuration and the increment of temperature strongly influence the local strains and local stresses inside a basic cell.

  13. Evaluation of Microstructure and Transport Properties of Deteriorated Cementitious Materials from Their X-ray Computed Tomography (CT Images

    Directory of Open Access Journals (Sweden)

    Michael Angelo B. Promentilla


    Full Text Available 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 (ψe 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 (τg 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.

  14. Computational Design of Non-natural Sugar Alcohols to Increase Thermal Storage Density: Beyond Existing Organic Phase Change Materials. (United States)

    Inagaki, Taichi; Ishida, Toyokazu


    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.

  15. Development of a strain rate dependent material model of human cortical bone for computer-aided reconstruction of injury mechanisms. (United States)

    Asgharpour, Zahra; Zioupos, Peter; Graw, Matthias; Peldschus, Steffen


    Computer-aided methods such as finite-element simulation offer a great potential in the forensic reconstruction of injury mechanisms. Numerous studies have been performed on understanding and analysing the mechanical properties of bone and the mechanism of its fracture. Determination of the mechanical properties of bones is made on the same basis used for other structural materials. The mechanical behaviour of bones is affected by the mechanical properties of the bone material, the geometry, the loading direction and mode and of course the loading rate. Strain rate dependency of mechanical properties of cortical bone has been well demonstrated in literature studies, but as many of these were performed on animal bones and at non-physiological strain rates it is questionable how these will apply in the human situations. High strain-rates dominate in a lot of forensic applications in automotive crashes and assault scenarios. There is an overwhelming need to a model which can describe the complex behaviour of bone at lower strain rates as well as higher ones. Some attempts have been made to model the viscoelastic and viscoplastic properties of the bone at high strain rates using constitutive mathematical models with little demonstrated success. The main objective of the present study is to model the rate dependent behaviour of the bones based on experimental data. An isotropic material model of human cortical bone with strain rate dependency effects is implemented using the LS-DYNA material library. We employed a human finite element model called THUMS (Total Human Model for Safety), developed by Toyota R&D Labs and the Wayne State University, USA. The finite element model of the human femur is extracted from the THUMS model. Different methods have been employed to develop a strain rate dependent material model for the femur bone. Results of one the recent experimental studies on human femur have been employed to obtain the numerical model for cortical femur. A

  16. A computer based approach for Material, Manpower and Equipment managementin the Construction Projects (United States)

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


    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

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

    Saiki, Toshiharu


    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.

  18. Computational study of sodium magnesium hydride for hydrogen storage applications (United States)

    Soto Valle, Fernando Antonio

    Hydrogen offers considerable potential benefits as an energy carrier. However, safe and convenient storage of hydrogen is one of the biggest challenges to be resolved in the near future. Sodium magnesium hydride (NaMgH 3) has attracted attention as a hydrogen storage material due to its light weight and high volumetric hydrogen density of 88 kg/m3. Despite the advantages, hydrogen release in this material occurs at approximately 670 K, which is well above the operable range for on-board hydrogen storage applications. In this regard, hydrogen release may be facilitated by substitution doping of transition-metals. This dissertation describes first-principles computational methods that enable an examination of the hydrogen storage properties of NaMgH3. The novel contribution of this dissertation includes a combination of crystal, supercell, and surface slab calculations that provides new and relevant insights about the thermodynamic and kinetic properties of NaMgH3. First-principles calculations on the pristine crystal structure provide a starting reference point for the study of this material as a hydrogen storage material. To the best of our knowledge, it is reported for the first time that a 25% mol doping concentration of Ti, V, Cu, and Zn dopants reduce the reaction enthalpy of hydrogen release for NaMgH3. The largest decrease in the DeltaH(298 K) value corresponds to the Zn-doped model (67.97 kJ/(mol H2)). Based on cohesive energy calculations, it is reported that at the 6.25% mol doping concentration, Ti and Zn dopants are the only transition metals that destabilize the NaMgH3 hydride. In terms of hydrogen removal energy, it is quantified that the energy cost to remove a single H from the Ti-doped supercell model is 0.76 eV, which is lower with respect to the pristine model and other prototypical hydrogen storage materials. From the calculation of electronic properties such as density of states, electron density difference, and charge population analysis

  19. Computer calculation of the Van Vleck second moment for materials with internal rotation of spin groups (United States)

    Goc, Roman


    This paper describes m2rc3, a program that calculates Van Vleck second moments for solids with internal rotation of molecules, ions or their structural parts. Only rotations about C 3 axes of symmetry are allowed, but up to 15 axes of rotation per crystallographic unit cell are permitted. The program is very useful in interpreting NMR measurements in solids. Program summaryTitle of the program: m2rc3 Catalogue number: ADUC Program summary URL: Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland License provisions: none Computers: Cray SV1, Cray T3E-900, PCs Installation: Poznań Supercomputing and Networking Center ( and Faculty of Physics, A. Mickiewicz University, Poznań, Poland ( Operating system under which program has been tested: UNICOS ver. on Cray SV1; UNICOS/mk on Cray T3E-900; Windows98 and Windows XP on PCs. Programming language: FORTRAN 90 No. of lines in distributed program, including test data, etc.: 757 No. of bytes in distributed program, including test data, etc.: 9730 Distribution format: tar.gz Nature of physical problem: The NMR second moment reflects the strength of the nuclear magnetic dipole-dipole interaction in solids. This value can be extracted from the appropriate experiment and can be calculated on the basis of Van Vleck formula. The internal rotation of molecules or their parts averages this interaction decreasing the measured value of the NMR second moment. The analysis of the internal dynamics based on the NMR second moment measurements is as follows. The second moment is measured at different temperatures. On the other hand it is also calculated for different models and frequencies of this motion. Comparison of experimental and calculated values permits the building of the most probable model of internal dynamics in the studied material. The program described

  20. Computation of Material Demand in the Risk Assessment and Mitigation Framework for Strategic Materials (RAMF-SM) Process (United States)


    Strategic Materials (RAMF-SM) Process Eleanor L. Schwartz James S. Thomason, Project Leader INSTITUTE FOR DEFENSE ANALYSES 4850 Mark Center Drive Alexandria...the Risk Assessment and Mitigation Framework for Strategic Materials (RAMF-SM) Process Eleanor L. Schwartz James S. Thomason, Project Leader iii...Inter-industry Forecasting Project at the University of Maryland (INFORUM), College Park , MD, 2001. Meade, Douglas S., et al. ILIAD. Inter-industry

  1. Study on Insulating Material by Renewable Resources (United States)

    Kurata, Yasuyuki; Kurosumi, Akihiro; Ishikawa, Keita

    Under circumstances such as global warming caused by carbon dioxide and other green house gas and crisis of depletion of fossil resources, recyclable resources such as biomass have captured the world's attention as reproducible resources alternative to petroleum. Therefore the technologies such to manufacture chemicals from recyclable resources have been developed for the achievement of measures for controlling global warming and the low carbon society. Recently, the bioplastic such as polylactic resin is applied to the home appliances and the automobile interior part as substitution of general-purpose plastic Moreover, the insulation oil from the vegetable oil has been put to practical use. The application of recyclable resources is extending in an electric field. In this paper, we introduce the characteristic and the problem of the insulating material made from recyclable resources in the field of the solid insulation.

  2. 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)


    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.

  3. Biomimicry in Product Design through Materials Selection and Computer Aided Engineering (United States)

    Alexandridis, G.; Tzetzis, D.; Kyratsis, P.


    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.

  4. A Case Study on the Use of Blended Learning to Encourage Computer Science Students to Study (United States)

    Perez-Marin, Diana; Pascual-Nieto, Ismael


    Students tend to procrastinate. In particular, Computer Science students tend to reduce the number of hours devoted to study concepts after class. In this paper, a case study on the use of Blended Learning to encourage Computer Science students to study is described. Furthermore, an experiment in which the reaction of 131 Computer Science…

  5. Semantic network mapping of religious material: testing multi-agent computer models of social theories against real-world data. (United States)

    Lane, Justin E


    Agent-based modeling allows researchers to investigate theories of complex social phenomena and subsequently use the model to generate new hypotheses that can then be compared to real-world data. However, computer modeling has been underutilized in regard to the understanding of religious systems, which often require very complex theories with multiple interacting variables (Braxton et al. in Method Theory Study Relig 24(3):267-290, 2012. doi: 10.1163/157006812X635709 ; Lane in J Cogn Sci Relig 1(2):161-180, 2013). This paper presents an example of how computer modeling can be used to explore, test, and further understand religious systems, specifically looking at one prominent theory of religious ritual. The process is continuous: theory building, hypothesis generation, testing against real-world data, and improving the model. In this example, the output of an agent-based model of religious behavior is compared against real-world religious sermons and texts using semantic network analysis. It finds that most religious materials exhibit unique scale-free small-world properties and that a concept's centrality in a religious schema best predicts its frequency of presentation. These results reveal that there adjustments need to be made to existing models of religious ritual systems and provide parameters for future models. The paper ends with a discussion of implications for a new multi-agent model of doctrinal ritual behaviors as well as propositions for further interdisciplinary research concerning the multi-agent modeling of religious ritual behaviors.

  6. A Qualitative Study of Students' Computational Thinking Skills in a Data-Driven Computing Class (United States)

    Yuen, Timothy T.; Robbins, Kay A.


    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…

  7. Environmental reference materials methods and case studies

    DEFF Research Database (Denmark)

    Schramm-Nielsen, Karina Edith


    be modelled when the length of the study is unknown. Experimental data has been collected from two stability studies of aqueous matrices. The first study regards the stability of TN NO² + ³-N and n in autoclaved wastewater samples over a period of 22 months. Data was collected specifically for this study....... 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...

  8. Vocabulary Materials and Study Strategies at Advanced Level (United States)

    Pauwels, Paul


    This paper reports on a quasi-experimental study of the effect of different vocabulary study materials and strategies used by upper-intermediate English as a foreign language students in higher education. Students were assigned a selection of 163 words from the Academic Word List and were provided with different types of study materials. They were…

  9. A Reflective Study into Children's Cognition When Making Computer Games (United States)

    Allsop, Yasemin


    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…

  10. A plea for neutral comparison studies in computational sciences.

    Directory of Open Access Journals (Sweden)

    Anne-Laure Boulesteix

    Full Text Available In computational science literature including, e.g., bioinformatics, computational statistics or machine learning, most published articles are devoted to the development of "new methods", while comparison studies are generally appreciated by readers but surprisingly given poor consideration by many journals. This paper stresses the importance of neutral comparison studies for the objective evaluation of existing methods and the establishment of standards by drawing parallels with clinical research. The goal of the paper is twofold. Firstly, we present a survey of recent computational papers on supervised classification published in seven high-ranking computational science journals. The aim is to provide an up-to-date picture of current scientific practice with respect to the comparison of methods in both articles presenting new methods and articles focusing on the comparison study itself. Secondly, based on the results of our survey we critically discuss the necessity, impact and limitations of neutral comparison studies in computational sciences. We define three reasonable criteria a comparison study has to fulfill in order to be considered as neutral, and explicate general considerations on the individual components of a "tidy neutral comparison study". R codes for completely replicating our statistical analyses and figures are available from the companion website

  11. CASKET: a computer code system for thermal and structural analyses of radioactive material transport and/or storage cask

    Energy Technology Data Exchange (ETDEWEB)

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


    A computer code system CASKET (CASK thermal and structural analyses and Evaluation code system) for the thermal and structural analyses which are indispensable for radioactive material transport and/or storage cask designs has been developed. The CASKET is a simplified computer code system to perform parametric analyses on sensitivity evaluations in designing a cask and conducting its safety analysis. Main features of the CASKET are as follow: (1) it is capable to perform impact analysis of casks with shock absorbers, (2) it is capable to perform impact analysis of casks with fins. (3) puncture analysis of casks is capable, (4) rocking analysis of casks during seismic load is capable, (5) material property data library are provided for impact analysis of casks, (6) material property data library are provided for thermal analysis of casks, (7) fin energy absorption data library are provided for impact analysis of casks with fins are and (8) not only main frame computers (OS MSP) but also work stations (OS UNIX) and personal computers (OS Windows 3.1) are available. In the paper, brief illustrations of calculation methods are presented. Some calculation results are compared with experimental ones to confirm the computer programs are useful for thermal and structural analyses. (author)

  12. CASKET: a computer code system for thermal and structural analyses of radioactive material transport and/or storage cask

    Energy Technology Data Exchange (ETDEWEB)

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


    A computer code system CASKET (CASK thermal and structural analyses and Evaluation code system) for the thermal and structural analyses which are indispensable for radioactive material transport and/or storage cask designs has been developed. The CASKET is a simplified computer code system to perform parametric analyses on sensitivity evaluations in designing a cask and conducting its safety analysis. Main features of the CASKET are as follow: (1) it is capable to perform impact analysis of casks with shock absorbers, (2) it is capable to perform impact analysis of casks with fins. (3) puncture analysis of casks is capable, (4) rocking analysis of casks during seismic load is capable, (5) material property data library are provided for impact analysis of casks, (6) material property data library are provided for thermal analysis of casks, (7) fin energy absorption data library are provided for impact analysis of casks with fins are and (8) not only main frame computers (OS MSP) but also work stations (OS UNIX) and personal computers (OS Windows 3.1) are available. In the paper, brief illustrations of calculation methods are presented. Some calculation results are compared with experimental ones to confirm the computer programs are useful for thermal and structural analyses. (author)

  13. Searching for new energetic materials: Computational design of novel nitro-substituted heterocyclic explosives (United States)

    Tsyshevsky, Roman V.; Pagoria, Philip; Kuklja, Maija M.


    The continuous search for safe and powerful energetic materials is an exciting research challenge that attracts experts in material science, chemistry, physics, and engineering. Elucidation of meaningful relationships between sensitivity and structures of explosives is a fundamental problem, which needs to be addressed to ensure successful design of new materials and improvements of existing energetics. In this paper, quantum-chemical DFT study of thermal decomposition of a series of recently synthesized oxadiazole-based explosives, BNFF (3,4-bis(4-Nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole-N-oxide), BNFF-1 (3,4-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole) and ANFF-1 (3-(4-amino-1,2,5-oxadiazol-3-yl)-4-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,5-oxadiazole) is presented. We also show how the knowledge of discovered interplay between the structures and thermal stability of these compounds is used to design several novel candidate heterocyclic energetic molecules, including DNBTT (2,7-dinitro-4H,9H-bis([1,2,4]triazolo)[1,5-b:1',5'-e][1,2,4,5]tetrazine), the compound with high thermal stability, which is on predicted to be par or better than that of TATB.

  14. Awareness of Accessibility Barriers in Computer-Based Instructional Materials and Faculty Demographics at South Dakota Public Universities (United States)

    Olson, Christopher


    Advances in technology and course delivery methods have enabled persons with disabilities to enroll in higher education at an increasing rate. Federal regulations state persons with disabilities must be granted equal access to the information contained in computer-based instructional materials, but faculty at the six public universities in South…

  15. 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


    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...

  16. Nondestructive material characterization of meteorites with synchrotron-based high energy x-ray phase micro-computed tomography (United States)

    Liu, Huiqiang; Xiao, Tiqiao; Xie, Honglan; Fu, Yanan; Zhang, Xueliang; Fan, Xiaoxi


    Synchrotron radiation based x-ray propagation-based micro-computed tomography (SRPCT) has been widely used to nondestructively access 3D structural information in many fields in the last decade. However, for strongly absorbed objects with small density-differential compositions, conventional SRPCT technique fails in providing high-contrast images for visualization of objects characteristic information except edge-enhancements at interfaces or boundaries of samples. In this study, we successfully employed the SRPCT technique with phase retrieval, the high energy x-ray phase-attenuation-duality (PAD) algorithm, into nondestructive material characterization of invaluable meteorite samples due to the greatly enhanced phase-contrast of different bulk material areas, as compared to conventional SRPCT on equal dose basis. Our experimental results demonstrated the PAD-SRPCT technique is superior to conventional SRPCT technique to access density and structure distributions of different meteorite compositions with high density resolution, owing to the striking contrast-to-noise ratio (CNR). In addition, a new mass-density measurement method was presented to estimate the mass density of different compositions in the meteorite sample based on the calibration of the imaging system.

  17. Solidification studies of automotive heat exchanger materials (United States)

    Carlberg, T.; Jaradeh, M.; Kamgou Kamaga, H.


    Modifications of the aluminum alloy AA 3003 have been studied to improve and tailorits properties for applications in automotive heat exchangers. Laboratory techniques have been applied to simulate industrial direct-chill casting, and some basic solidification studies have been conducted. The results are coupled to structures observed in industrial-size ingots and discussed in terms of structure-property relations.

  18. A Study of Time Dependent Response of Ceramic Materials (United States)

    Hemann, John


    The research accomplishments under this grant were very extensive in the areas of the development of computer software for the design of ceramic materials. Rather than try to summarize all this research I have enclosed research papers and reports which were completed with the funding provided by the grant. These papers and reports are listed below. Additionally a large amount of technology transfer occurred in this project and a significant number of national awards were received.

  19. Study and Application of Sealing Material for Coke Oven Chamber

    Institute of Scientific and Technical Information of China (English)

    GAN Feifang; TAI Li


    A kind of dry refractory sealing material has been developed to repair the fine cracks in coke oven chamber. With silica sand as the main raw material, the sealing material is blown into coke oven chamber by compressed air while being applied, and bonded to brick surface or filled in fine cracks of chamber under right pressure. The physical properties of the material are similar to those of silica bricks during its application. So it can be adapted to conditions of coke oven and has good service life. The study and application results of the sealing material are described in this paper.

  20. Computed tomographic study in young epileptics in Kashmir, India

    Directory of Open Access Journals (Sweden)

    Mohd Ashraf


    Full Text Available Background: Infectious diseases like neurocysticercosis and neurotuberculosis are endemic in Indian subcontinent and are important causes of epilepsy. Epileptic children are prone to have poor school performance, higher levels of anxiety and depression apart from low self esteem. These treatable condition could be easily picked up on neuroimaging like cranial computed tomography (CT scan and treated accordingly at an earliest. Objectives: To assess the role of cranial computed tomography scan in children having epilepsy. Material and Methods: Seventy two children between the age of 1 month and 14 years were prospectively enrolled, who had atleast two unprovoked seizures greater than 24 hours apart, and all those children where seizures result from acute central nervous system insult were meticulously excluded. Diagnosis of epilepsy was based on detailed history, thorough clinical examination, routine laboratory tests with additional specific tests like electroencephalogram (EEG and CT scan brain. Results: Males constituted 62.5% and females 37.5% of our sample (p=0.247. The EEG was abnormal in 68.1% of all subjects, among which EEG was abnormal in 69.8% of generalized seizures, 64.7% in partial seizures and 1% in undetermined seizures. The spectrum of various seizure types in our study was generalized seizures in 73.6%, partial seizures in 23.6% & undetermined seizures in 2.8%. The incidence of these lesions in hospitalized young epileptics was 31.9%, in order of their frequency, it was cerebral atrophy and dilated ventricle (18.8% each; calcifications (15.5%; encephalomalacia and pachygyria (9.4% each; HIE changes, tuberous sclerosis (6.3% each; leucodystrophy, thin corpus callosum, large cisterna magna, granuloma and periventricular leukomalacia (3.1% each. The intracranial structural lesions were present in 22.6% of generalized seizures, 64.7% of partial seizures, none of undetermined seizures (p=0.004. Conclusion: Abnormal cranial CT scan

  1. 展开大学英语语法学习双翼——语法学习计算机辅助教材探究%Stretching the Wings for the Acquisition of College English Grammar —— A Study of Computer - assisted Materials for College English Grammar

    Institute of Scientific and Technical Information of China (English)

    朱万智; 宋晓英; 张宇


    Through analyzing the traditional teaching methods of English grammar, this paper discussed how to develop and construct a computer - assisted material system for college English grammar, such as College English grammar software, multi - dimensional textbooks, teaching plans and software for self - testing. It suggested that a computer - assisted material system for College English Gram- mar, combined with modern teaching techniques, has advantages and functions beyond the possibilities of the traditional textbooks. Therefore, the new material system has the potential for a comprehensive application in College English teaching and learning.%文章通过对传统英语语法教学方法的分析,论述了如何开发和构建大学英语语法计算机辅助教材体系,如大学英语语法学习软件、立体化教材、教案、自我测试软件等。认为采用了现代教育技术的大学英语语法计算机辅助教材体系具有传统纸质教材无法比拟的优势和功能。因此,这种新型教材体系可以在大学英语教与学中广泛应用。

  2. 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)


    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.

  3. A study of mesoscale simulations for planar shock experiments on heterogeneous granular materials (United States)

    Schumaker, Merit G.

    There is an interest in producing accurate and reliable computer simulations to predict the dynamic behavior of heterogeneous materials and to use these simulations to gain further insight into experimental results. In so doing, a more complete understanding of the multiple-length scales involved in heterogeneous material compaction can be obtained. Mesoscale computer simulations of dynamically shocked materials have proven to be a beneficial resource in unraveling data not observed in planar shock impact experiments, such as stress and temperature interactions between grains. The modeled mono-dispersed geometry of particles, the densities of each material, equations of state, material properties and many other factors affect the simulated outcomes. By studying and analyzing these variables, many of which highlight the difference between experimental and simulated results, there manifests additional insight into the shock dynamics of the different heterogeneous granular materials. The heterogeneous materials in this study were created both by a "shake and pack" method, where individual grains were randomly seeded into the computational domain and grown until the grains matched the experimental volume fraction and average diameter. Three planar shock experiments were utilized to validate simulation models and parameters: 1. Brake pad powder compaction at Marquette University, 2. Dry sand experiments at Georgia Tech, and 3. Release of dry sand at Cambridge University. Planar shock impact experiments were simulated using two different hydrocode packages: CTH and iSALE. Validated models are then used to setup future dry, water, and possible ice saturated sand release experiments. Particle velocity and stress traces obtained from the computer simulations were compared to VISAR, PDV, and Manganin gage measurements obtained from experiments. The results from simulations are compared to experiments and discussed in this document.

  4. Case studies in intelligent computing achievements and trends

    CERN Document Server

    Issac, Biju


    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


    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...

  6. Studies on selected polymeric materials using the photoacoustic spectroscopic technique

    Institute of Scientific and Technical Information of China (English)

    Hukum Singh


    Polymethylmethacrylate-graft-polybisphenol-A-carbonate (PMMA-G-PC) with 50% grafting is synthesized. The acid (0.18 M, 100 ml) in air at (45±12) ℃ 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.

  7. Computer Modeling of Electrostatic Aggregation of Granular Materials in Planetary and Astrophysical Settings (United States)

    Marshall, J.; Sauke, T.


    Electrostatic forces strongly influence the behavior of granular materials in both dispersed (cloud) systems and semi-packed systems. These forces can cause aggregation or dispersion of particles and are important in a variety of astrophysical and planetary settings. There are also many industrial and commercial settings where granular matter and electrostatics become partners for both good and bad. This partnership is important for human exploration on Mars where dust adheres to suits, machines, and habitats. Long-range Coulombic (electrostatic) forces, as opposed to contact-induced dipoles and van der Waals attractions, are generally regarded as resulting from net charge. We have proposed that in addition to net charge interactions, randomly distributed charge carriers on grains will result in a dipole moment regardless of any net charge. If grains are unconfined, or fluidized, they will rotate so that the dipole always induces attraction between grains. Aggregates are readily formed, and Coulombic polarity resulting from the dipole produces end-to-end stacking of grains to form filamentary aggregates. This has been demonstrated in USML experiments on Space Shuttle where microgravity facilitated the unmasking of static forces. It has also been demonstrated in a computer model using grains with charge carriers of both sign. Model results very closely resembled micro-g results with actual sand grains. Further computer modeling of the aggregation process has been conducted to improve our understanding of the aggregation process, and to provide a predictive tool for microgravity experiments slated for Space Station. These experiments will attempt to prove the dipole concept as outlined above. We have considerably enhanced the original computer model: refinements to the algorithm have improved the fidelity of grain behavior during grain contact, special attention has been paid to simulation time steps to enable establishment of a meaningful, quantitative time axis

  8. New preparation of fish material for interlaboratory study on PFCs

    NARCIS (Netherlands)

    Korytar, P.; Lohman, M.; Kwadijk, C.J.A.F.; Barneveld, van E.


    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.

  9. Two Studies Examining Argumentation in Asynchronous Computer Mediated Communication (United States)

    Joiner, Richard; Jones, Sarah; Doherty, John


    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…

  10. An Empirical Study of Pupils' Attitudes to Computers and Robots. (United States)

    Moore, J. L.


    Describes a study which utilized a Likert type questionnaire to assess seven scales of secondary pupils' attitudes toward computers and robotics (school, leisure, career, employment, social, threat, future) and investigated pupils' scores on functions of their sex, general academic ability, course of study, and microcomputer experience. (MBR)

  11. Experiences of Computer Science Curriculum Design: A Phenomenological Study (United States)

    Sloan, Arthur; Bowe, Brian


    This paper presents a qualitative study of 12 computer science lecturers' experiences of curriculum design of several degree programmes during a time of transition from year-long to semesterised courses, due to institutional policy change. The background to the study is outlined, as are the reasons for choosing the research methodology. The main…

  12. Brain-computer interfacing under distraction: an evaluation study

    DEFF Research Database (Denmark)

    Brandl, Stephanie; Frølich, Laura; Höhne, Johannes;


    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...

  13. Experiences of Computer Science Curriculum Design: A Phenomenological Study (United States)

    Sloan, Arthur; Bowe, Brian


    This paper presents a qualitative study of 12 computer science lecturers' experiences of curriculum design of several degree programmes during a time of transition from year-long to semesterised courses, due to institutional policy change. The background to the study is outlined, as are the reasons for choosing the research methodology. The main…

  14. Electrostatic Levitation for Studies of Additive Manufactured Materials (United States)

    SanSoucie, Michael P.; Rogers, Jan R.; Tramel, Terri


    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

  15. 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


    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.

  16. Challenges in Integrated Computational Structure - Material Modeling of High Strain-Rate Deformation and Failure in Heterogeneous Materials (United States)


    author(s) and should not contrued as an official Department of the Army position, policy or decision, unless so designated by other documentation . 9...Structure Heterogeneous Material Models REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8...Bronkhorst of LANL . This was followed by a 30 min. panel discussion. (iv) Plenary session # 2 on Probabilistic Modeling & Uncertainty


    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...


    CERN Multimedia

    I. Fisk


    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...

  19. Knowledge and attitude towards computer usage among health care students in India -across sectional study

    Directory of Open Access Journals (Sweden)

    A Anitha


    Full Text Available Background: As computers and internet usage is increasing rapidly in all fields more so with health care systems, an immediate attention on the computer knowledge and its application is needed for health professionals. Aim: To assess the knowledge of computer technology and their attitude towards its usage among health care students in an institution located in India. Materials & Method: A cross-sectional questionnaire based survey was conducted among dental, medical House surgeons (interns and final year nursing students of Mamata Institutions in Khammam, Andhra Pradesh, India. A pretested closed ended questionnaire was prepared and was distributed. Results: A total of 260 subjects had participated in the study (female=170, male=90. About 42% of the subjects had their own computer or laptop; 84% of the students thought that a separate subject of computers should be added to the curriculum and 87% of the students thought that computers were necessary to manage patients′ information. Conclusions: There is a need to improve the health care students′ knowledge on computer education and application of this knowledge in to their clinical practice.

  20. A Resonant Damping Study Using Piezoelectric Materials (United States)

    Min, J. B.; Duffy, K. P.; Choi, B. B.; Morrison, C. R.; Jansen, R. H.; Provenza, A. J.


    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%.

  1. Multimillion Atom Simulations of Nanostructured Materials on Parallel Computers ---Sintering and Consolidation, Fracture, and Oxidation--- (United States)

    Vashishta, P.; Bachlechner, M. E.; Campbell, T.; Kalia, R. K.; Kikuchi, H.; Kodiyalam, S.; Nakano, A.; Ogata, S.; Shimojo, F.; Walsh, P.

    Multiresolution molecular-dynamics approach for multimillion atom simulations has been used to investigate structural properties, mechanical failure in ceramic materials, and atomic-level stresses in nanoscale semiconductor/ceramic mesas (Si/Si3N4). Crack propagation and fracture in silicon nitride, silicon carbide, gallium arsenide, and nanophase ceramics are investigated. We observe a crossover from slow to rapid fracture and a correlation between the speed of crack propagation and morphology of fracture surface. A 100 million atom simulation is carried out to study crack propagation in GaAs. Mechanical failure in the Si/Si3N4 interface is studied by applying tensile strain parallel to the interface. Ten million atom molecular dynamics simulations are performed to determine atomic-level stress distributions in a 54 nm nanopixel on a 0.1 μm silicon substrate. Multimillion atom simulations of oxidation of aluminum nanoclusters and nanoindentation in silicon nitride are also discussed.

  2. Combinatorial computational chemistry approach for materials design: applications in deNOx catalysis, Fischer-Tropsch synthesis, lanthanoid complex, and lithium ion secondary battery. (United States)

    Koyama, Michihisa; Tsuboi, Hideyuki; Endou, Akira; Takaba, Hiromitsu; Kubo, Momoji; Del Carpio, Carlos A; Miyamoto, Akira


    Computational chemistry can provide fundamental knowledge regarding various aspects of materials. While its impact in scientific research is greatly increasing, its contributions to industrially important issues are far from satisfactory. In order to realize industrial innovation by computational chemistry, a new concept "combinatorial computational chemistry" has been proposed by introducing the concept of combinatorial chemistry to computational chemistry. This combinatorial computational chemistry approach enables theoretical high-throughput screening for materials design. In this manuscript, we review the successful applications of combinatorial computational chemistry to deNO(x) catalysts, Fischer-Tropsch catalysts, lanthanoid complex catalysts, and cathodes of the lithium ion secondary battery.

  3. Rotating Detonation Combustion: A Computational Study for Stationary Power Generation (United States)

    Escobar, Sergio

    The increased availability of gaseous fossil fuels in The US has led to the substantial growth of stationary Gas Turbine (GT) usage for electrical power generation. In fact, from 2013 to 2104, out of the 11 Tera Watts-hour per day produced from fossil fuels, approximately 27% was generated through the combustion of natural gas in stationary GT. The thermodynamic efficiency for simple-cycle GT has increased from 20% to 40% during the last six decades, mainly due to research and development in the fields of combustion science, material science and machine design. However, additional improvements have become more costly and more difficult to obtain as technology is further refined. An alternative to improve GT thermal efficiency is the implementation of a combustion regime leading to pressure-gain; rather than pressure loss across the combustor. One concept being considered for such purpose is Rotating Detonation Combustion (RDC). RDC refers to a combustion regime in which a detonation wave propagates continuously in the azimuthal direction of a cylindrical annular chamber. In RDC, the fuel and oxidizer, injected from separated streams, are mixed near the injection plane and are then consumed by the detonation front traveling inside the annular gap of the combustion chamber. The detonation products then expand in the azimuthal and axial direction away from the detonation front and exit through the combustion chamber outlet. In the present study Computational Fluid Dynamics (CFD) is used to predict the performance of Rotating Detonation Combustion (RDC) at operating conditions relevant to GT applications. As part of this study, a modeling strategy for RDC simulations was developed. The validation of the model was performed using benchmark cases with different levels of complexity. First, 2D simulations of non-reactive shock tube and detonation tubes were performed. The numerical predictions that were obtained using different modeling parameters were compared with

  4. EFL Teachers' Knowledge of the Use and Development of Computer-Assisted Language Learning (CALL) Materials (United States)

    Dashtestani, Reza


    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…

  5. Embedding Designed Deformation: towards the computational design of graded material components

    DEFF Research Database (Denmark)

    Nicholas, Paul


    Recognising that the process of making materials affords opportunities not available when using existing natural or off-the-shelf materials, the focus of this paper is upon abstraction strategies by which the mechanical properties of composite materials might be engaged within digital architectural...

  6. Multicapillary optics for materials science studies

    Energy Technology Data Exchange (ETDEWEB)

    Scardi, P.; Setti, S.; Leoni, M. [Trento Univ. (Italy). Dipt. di Ingegneria dei Materiali


    XRD patterns from a standard polycrystalline gold film, collected by a parallel beam goniometer equipped with a conventional cross-slits collimator were compared with those obtained by replacing the incident beam optics with a multicapillary collimator. Considerable improvements can be achieved by using the new optics: (a) a much higher fraction of the X-ray beam produced by a conventional sealed tube can be used to build the diffracted signal, provided that a sufficiently wide sample area is available for measurement (diameter > 1 mm); (b) the limited beam divergence ({approx}0.3 ) gives a good stability and precision, in terms of negligible systematic errors in peak position due to sample {psi}- and {omega}-tilting; (c) instrumental profiles are much narrower than those obtained by the conventional cross-slits collimator; (d) width and shape of the instrumental profile are almost unaffected by sample tilting. The considerable interest in this device is increased by considering that features (b), (c) and (d) were verified also for relatively low 2{theta} angles (30-40 ): this is of great importance for thin film studies, where most of the available information comes from low diffraction order profiles; in addition, the increased signal intensity greatly helps to reduce measurement time (or to improve statistics). Advantages and drawbacks of the new optics are described in this paper, together with some practical examples of use. (orig.)


    Institute of Scientific and Technical Information of China (English)

    Lucian A.Lucia; Qiujuan Liu


    The rationale for this research is to more efficiently produce higher yield and uniform linerboard grade pulps comparable to current manufacturing technologies using a modified kraft cooking characterized by a green liquor pretreatment stage. The pretreatment stage employed is considered a low capital method that employs mill green liquor at the front end of cook. Since green liquor typically has a high sulfidity to alkalinity ratio, it is ideal for significant improvements to pulp properties.The manufacture of linerboard grade pulps in this study has been accomplished in the laboratory by pretreating industrially supplied southern pine chips with varying concentrations of green liquor and anthraquinone (AQ). The influence of the pretreatment level of green liquor, pretreatment time, AQ, kraft cooking AA dosage, and H-factor on the properties of the pulp obtained was investigated. The potential benefits of this green liquor pretreatment pulping technology for the paper industry are a decrease in alkali digester consumption, shortened cooking times, and pulp yield increases.

  8. Computational Modeling and Experimental Characterization of Martensitic Transformations in Nicoal for Self-Sensing Materials (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.


    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.

  9. X-ray Digital Radiography and Computed Tomography of ICF and HEDP Materials, Subassemblies and Targets

    Energy Technology Data Exchange (ETDEWEB)

    Brown, W D; Martz Jr., H E


    Inertial confinement fusion (ICF) and high energy density physics (HEDP) research are being conducted at large laser facilities, such as the University of Rochester's Laboratory for Laser Energetics OMEGA facility and the Lawrence Livermore National Laboratory's (LLNL) National Ignition Facility (NIF). At such facilities, millimeter-sized targets with micrometer structures are studied in a variety of hydrodynamic, radiation transport, equation-of-state, inertial confinement fusion and high-energy density experiments. The extreme temperatures and pressures achieved in these experiments make the results susceptible to imperfections in the fabricated targets. Targets include materials varying widely in composition ({approx}3 < Z < {approx}82), density ({approx}0.03 to {approx}20 g/cm{sup 3}), geometry (planar to spherical) and embedded structures (joints to subassemblies). Fabricating these targets with structures to the tolerances required is a challenging engineering problem the ICF and HEDP community are currently undertaking. Nondestructive characterization (NDC) provides a valuable tool in material selection, component inspection, and the final pre-shot assemblies inspection. X-rays are a key method used to NDC these targets. In this paper we discuss X-ray attenuation, X-ray phase effects, and the X-ray system used, its performance and application to characterize low-temperature Raleigh-Taylor and non-cryogenic double-shell targets.

  10. Computational studies of model disordered and strongly correlated electronic systems (United States)

    Johri, Sonika

    The theory of non-interacting electrons in perfect crystals was completed soon after the advent of quantum mechanics. Though capable of describing electron behaviour in most simple solid state physics systems, this approach falls woefully short of describing condensed matter systems of interest today, and designing the quantum devices of the future. The reason is that nature is never free of disorder, and emergent properties arising from interactions can be clearly seen in the pure, low-dimensional materials that can be engineered today. In this thesis, I address some salient problems in disordered and correlated electronic systems using modern numerical techniques like sparse matrix diagonalization, density matrix renormalization group (DMRG), and large disorder renormalization group (LDRG) methods. The pioneering work of P. W. Anderson, in 1958, led to an understanding of how an electron can stop diffusing and become localized in a region of space when a crystal is sufficiently disordered. Thus disorder can lead to metal-insulator transitions, for instance, in doped semiconductors. Theoretical research on the Anderson disorder model since then has mostly focused on the localization-delocalization phase transition. The localized phase in itself was not thought to exhibit any interesting physics. Our work has uncovered a new singularity in the disorder-averaged inverse participation ratio of wavefunctions within the localized phase, arising from resonant states. The effects of system size, dimension and disorder distribution on the singularity have been studied. A novel wavefunction-based LDRG technique has been designed for the Anderson model which captures the singular behaviour. While localization is well established for a single electron in a disordered potential, the situation is less clear in the case of many interacting particles. Most studies of a many-body localized phase are restricted to a system which is isolated from its environment. Such a condition

  11. Study of operational parameters impacting helicopter fuel consumption. [using computer techniques (computer programs) (United States)

    Cross, J. L.; Stevens, D. D.


    A computerized study of operational parameters affecting helicopter fuel consumption was conducted as an integral part of the NASA Civil Helicopter Technology Program. The study utilized the Helicopter Sizing and Performance Computer Program (HESCOMP) developed by the Boeing-Vertol Company and NASA Ames Research Center. An introduction to HESCOMP is incorporated in this report. The results presented were calculated using the NASA CH-53 civil helicopter research aircraft specifications. Plots from which optimum flight conditions for minimum fuel use that can be obtained are presented for this aircraft. The results of the study are considered to be generally indicative of trends for all helicopters.

  12. Computational studies of competing phases in model Hamiltonians (United States)

    Jiang, Mi

    Model Hamiltonians play an important role in our understanding of both quantum and classical systems, such as strongly correlated unconventional superconductivity, quantum magnetism, non-fermi liquid heavy fermion materials and classical magnetic phase transitions. The central problem is how models with many degrees of freedom choose between competing ground states, e.g. magnetic, superconducting, metallic, insulating as the degree of thermal and quantum fluctuations is varied. This dissertation focuses on the numerical investigation of several important model Hamiltonians. Specifically, we used the determinant Quantum Monte Carlo (DQMC) to study three Hubbard-like models: the Fermi-Hubbard model with two regions of different interaction strength, the Fermi-Hubbard model with a spin-dependent band structure, and the related periodic Anderson model (PAM). The first model used was to explore inter-penetration of metallic and Mott insulator physics across a Metal-Mott Insulator interface by computing the magnetic properties and spectral functions. As a minimal model of a half metallic magnet, the second model was used to explore the impact of on-site Hubbard interaction U, finite temperature, and an external (Zeeman) magnetic field on a bilayer tight-binding model with spin-dependent hybridization. We use PAM to study the Knight shift anomaly in heavy fermion materials found in Nuclear magnetic resonance (NMR) experiments and confirm several predictions of the two-fluid theory accounting for the anomaly. Another application of the Hubbard model described in this dissertation is the investigation on the effects of spin-dependent disorder on s-wave superconductors based on the attractive Hubbard model. Here we used the Bogoliubov-de Gennes (BdG) self-consistent approach instead of quantum simulations. The spin-dependent random potential was shown to induce distinct transitions at which the energy gap and average order parameter vanish, generating an intermediate gapless

  13. Mass spectrometric thermodynamic studies of oxide systems and materials (United States)

    Stolyarova, V. L.


    Progress in methods of synthesis of advanced materials as well as utilization of such materials at high temperatures requires information on the vaporization processes and thermodynamic properties of oxide systems. The optimal experimental method for these purposes is high-temperature mass spectrometry. This review summarizes and classifies experimental results obtained in mass spectrometric studies of the high-temperature thermodynamic properties of oxide systems and materials carried out in the last two decades. Published data on the vaporization processes and thermodynamic properties of oxide materials for high-temperature technologies are discussed from the standpoint of acid-base concept and model approaches including statistical thermodynamic methods. The bibliography includes 248 references.

  14. Computer

    CERN Document Server

    Atkinson, Paul


    The pixelated rectangle we spend most of our day staring at in silence is not the television as many long feared, but the computer-the ubiquitous portal of work and personal lives. At this point, the computer is almost so common we don't notice it in our view. It's difficult to envision that not that long ago it was a gigantic, room-sized structure only to be accessed by a few inspiring as much awe and respect as fear and mystery. Now that the machine has decreased in size and increased in popular use, the computer has become a prosaic appliance, little-more noted than a toaster. These dramati

  15. In vivo adsorption study of fluoxetine using carbon materials,


    Nabais, Joao; Tinoco, Teresa; Morais, Julio


    The in vivo adsorption of fluoxetine by a commercial activated carbon and a laboratory prepared activated carbon fibre were studied. The results showthat the carbon materials tested are not toxic toWistar rats and both materials had a high efficacy in the in vivo adsorption of fluoxetine preventing toxicity of the drug overdose administered to the animals.

  16. Integrating Material on the Internment into Anthropology and Women's Studies. (United States)

    Sacks, Karen B.


    Describes plans to use material from a seminar on integrating material about the Japanese-American internment in World War II into the curriculum of the University of California Los Angeles. Describes efforts to develop a unit on the gender and racial dimensions of internment for a women's studies course. (SLD)

  17. Computerized Atlases: The Potential of Computers in Social Studies. (United States)

    de Leeuw, G.; Waters, N. M.


    Examines the use of computer atlases to see how they might contribute to the attainment of established social studies goals. Reviews advantages and disadvantages of existing software and hardware. Describes the potentials of computerized atlases and the hardware required to support such uses. (JDH)

  18. Computerized Atlases: The Potential of Computers in Social Studies. (United States)

    de Leeuw, G.; Waters, N. M.


    Examines the use of computer atlases to see how they might contribute to the attainment of established social studies goals. Reviews advantages and disadvantages of existing software and hardware. Describes the potentials of computerized atlases and the hardware required to support such uses. (JDH)

  19. Defining Effectiveness Using Finite Sets A Study on Computability

    DEFF Research Database (Denmark)

    Macedo, Hugo Daniel dos Santos; Haeusler, Edward H.; Garcia, Alex


    This paper studies effectiveness in the domain of computability. In the context of model-theoretical approaches to effectiveness, where a function is considered effective if there is a model containing a representation of such function, our definition relies on a model provided by functions betwe...

  20. Computer-Based Information Services in Medicine: A Feasibility Study. (United States)

    Cox, P. H.; And Others

    The objectives of this study were to examine the need and potential demand for computer-based information services in the University of Otago medical libraries, to evaluate the various databases of interest, and to recommend the best means of access to such services. Data were collected through user and library surveys, an extensive literature…