WorldWideScience

Sample records for density materials hedms

  1. Molecular Design for High Energy Density Materials%高能量密度材料的分子设计

    Institute of Scientific and Technical Information of China (English)

    董喜城; 陈敏伯

    2000-01-01

    CERIUS2 program was employed on an Indigo2 SGI workstation to investigate the vacuum and crystal structures of the high energy density materials (HEDM). Over 20 known HEDM were first studied with an emphasis on the enthalpy of formation, optimal lattice forms, crystal lattice energy and crystal density. On the basis of the study, about 20 potential HEDM were designed.

  2. Theoretical Prediction of the Heats of Formation, Densities and Relative Sensitivities, and/or Synthetic Approaches Toward the Synthesis of High Energy Dense Materials (HEDMs): 3,5-Dinitro-1,3,5-Oxadiazinane, Bis-Adjacent RDX, Bis-Adjacent HMX, 4,4’,6,6’-Tetranitro-1,1’-Bis(N-oxide)-5,5’,6,6’-4H,4’H-5,5’-Bisimidazo Oxadiazole, and the Open-Cage Derivative of CL-20

    Science.gov (United States)

    2015-09-01

    HMX , 4,4’,6,6’- Tetranitro-1,1’-Bis(N-oxide)-5,5’,6,6’-4H,4’H- 5,5’-Bisimidazo Oxadiazole, and the Open- Cage Derivative of CL-20...HEDMs): 3,5-Dinitro-1,3,5-Oxadiazinane, Bis-Adjacent RDX, Bis-Adjacent HMX , 4,4’,6,6’- Tetranitro-1,1’-Bis(N-oxide)-5,5’,6,6’-4H,4’H- 5,5’-Bisimidazo...Materials (HEDMs): 3,5-Dinitro-1,3,5-Oxadiazinane, Bis-Adjacent RDX, Bis-Adjacent HMX , 4,4’,6,6’-Tetranitro-1,1’-Bis(N-oxide)-

  3. Molecular Design and Property Prediction for a Series of Novel Dicyclic Cyclotrimethylene Trinitramines (RDX) Derivatized as High Energy Density Materials.

    Science.gov (United States)

    Shen, Cheng; Wang, Pengcheng; Lu, Ming

    2015-07-23

    Quantum chemistry calculations and thermodynamics methods were carried out to screen out novel high energy density materials (HEDMs) from several new derivatives with dicyclic structures of Cyclotrimethylene trinitramine (RDX). Their volumes, densities, heats of formation, detonation properties and impact sensitivities have been calculated with thermodynamics methods under DFT B3LYP 6-31++g (d, p) level and all of these compounds exhibit good performance as HEDMs. Especially, R4 has given outstanding values as a potential HEDM. Its crystal density (2.07 g/cm(3)), heat of detonation (1.67 kJ/g), detonation velocity (10051m/s), and detonation pressure (48.5 GPa) are even higher than those of CL-20 while its impact sensitivity (h50, 16 cm) remains a relative safety value. The results indicate that the derivative work in common explosives is a good strategy which can design novel HEDMs with high energetic properties and low sensitivity. And furthermore, some mature processes can be used to synthesize them.

  4. Dancing with Energetic Nitrogen Atoms: Versatile N-Functionalization Strategies for N-Heterocyclic Frameworks in High Energy Density Materials.

    Science.gov (United States)

    Yin, Ping; Zhang, Qinghua; Shreeve, Jean'ne M

    2016-01-19

    Nitrogen-rich heterocycles represent a unique class of energetic frameworks featuring high heats of formation and high nitrogen content, which have generated considerable research interest in the field of high energy density materials (HEDMs). Although traditional C-functionalization methodology of aromatic hydrocarbons has been fully established, studies on N-functionalization strategies of nitrogen-containing heterocycles still have great potential to be exploited by virtue of forming diverse N-X bonds (X = C, N, O, B, halogen, etc.), which are capable of regulating energy performance and the stability of the resulting energetic compounds. In this sense, versatile N-functionalization of N-heterocyclic frameworks offers a flexible strategy to meet the requirements of developing new-generation HEDMs. In this Account, the role of strategic N-functionalization in designing new energetic frameworks, including the formation of N-C, N-N, N-O, N-B and N-halogen bonds, is emphasized. In the family of N-functionalized HEDMs, energetic derivatives, by virtue of forming N-C bonds, are the most widely used type due to the good nucleophilic capacity of most heterocyclic backbones. Although introduction of carbon tends to decrease energetic performance, significant improvement in material sensitivity makes this strategy attractive for safety concerns. More importantly, most "explosophores" can be readily introduced into the N-C linkage, thus providing a promising route to various HEDMs. Formation of additional N-N bonds typically gives rise to higher heats of formation, implying the potential enhancement in detonation performance. In many cases, the increased hydrogen bonding interactions within N-N functionalized heterocycles also improve thermal stability accordingly. Introduction of a single N,N'-azo bridge into several azole moieties leads to an extended nitrogen chain, demonstrating a new strategy for designing high-nitrogen compounds. The strategy of N-O functionalization

  5. 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.

    Science.gov (United States)

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

    2011-10-27

    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.

  6. Synthesis, characterization, and properties of peroxo-based oxygen-rich compounds for potential use as greener high energy density materials

    Science.gov (United States)

    Gamage, Nipuni-Dhanesha Horadugoda

    One main aspect of high energy density material (HEDM) design is to obtain greener alternatives for HEDMs that produce toxic byproducts. Primary explosives lead azide, lead styphnate, and mercury fulminate contain heavy metals that cause heavy metal poisoning. Leaching of the widely used tertiary explosive NH4ClO4 into groundwater has resulted in human exposure to ClO4-- ions, which cause disruptions of thyroid related metabolic pathways and even thyroid cancer. Many research efforts to find replacements have gained little success. Thus, there is a need for greener HEDMs. Peroxo-based oxygen-rich compounds are proposed as a potential new class of greener HEDMs due to the evolution of CO2 and/or CO, H2O, and O 2 as the main decomposition products. Currently, triacetone triperoxide (TATP), diacetone diperoxide (DADP), hexamethylene triperoxide diamine (HMTD), and methyl ethyl ketone peroxide (MEKP) are the only well-studied highly energetic peroxides. However, due to their high impact and friction sensitivities, low thermal stabilities, and low detonation velocities they have not found any civil or military HEDM applications. In this dissertation research, we have synthesized and fully characterized four categories of peroxo-based compounds: tert-butyl peroxides, tert-butyl peroxy esters, hydroperoxides, and peroxy acids to perform a systematic study of their sensitivities and the energetic properties for potential use as greener HEDMs. tert-Butyl peroxides were not sensitive to impact, friction, or electrostatic spark. Hence, tert-butyl peroxides can be described as fairly safe peroxo-based compounds to handle. tert-Butyl peroxy esters were all surprisingly energetic (4896--6003 m/s), despite the low oxygen and nitrogen contents. Aromatic tert -butyl peroxy esters were much lower in impact and friction sensitivities with respect to the known peroxo-based explosives. These are among the first low sensitivity peroxo-based compounds that can be categorized as secondary

  7. Molecular dynamics simulations on the structures and properties of ε-CL-20-based PBXs——Primary theoretical studies on HEDM formulation design

    Institute of Scientific and Technical Information of China (English)

    XU; XiaoJuan; XIAO; JiJun; HUANG; Hui; LI; JinShan; XIAO; HeMing

    2007-01-01

    Five polymer bonded explosives (PBXs) with the base explosiveε-CL-20 (hexanitrohexaazaisowurtzitane), the most important high energy density compound (HEDC), and five polymer binders (Estane 5703, GAP, HTPB, PEG, and F2314) were constructed. Molecular dynamics (MD) method was employed to investigate their binding energies (Ebind), compatibility, safety, mechanical properties, and energetic properties. The information and rules were reported for choosing better binders and guiding formulation design of high energy density material (HEDM). According to the calculated binding energies, the ordering of compatibility and stability of the five PBXs was predicted as ε-CL-20/PEG > ε-CL-20/ Estane5703 ≈ε-CL-20/GAP > ε-CL-20/HTPB > ε-CL-20/F2314. By pair correlation function g(r) analyses, hydrogen bonds and vdw are found to be the main interactions between the two components. The elasticity and isotropy of PBXs based ε-CL-20 can be obviously improved more than pure ε-CL-20 crystal. It is not by changing the molecular structures of ε-CL-20 for each binder to affect the sensitivity. The safety and energetic properties of these PBXs are mainly influenced by the thermal capability (C°p) and density (ρ) of binders, respectively.

  8. Proceedings of the High Energy Density Materials Contractors Conference Held on 25-28 February 1990 in Long Beach, California

    Science.gov (United States)

    1990-05-01

    4 LUI 0 F- u u < cc z cc U- m< t CD z U - < 4 ) _ u w 282 Stabilization of HEDM Materials S.D. Thompson, R.A. van Opijnen, M.I. Kenney1 , S.L...Soc. (in press). 5. M. Rincon , N. Kirchner and M.T. Bowers, Int. J. Mass Spectrom. lion Proc. 86, 369 (1988). 5. The ground state of carbon ion, C

  9. Update to Computational Aspects of Nitrogen-Rich HEDMs

    Science.gov (United States)

    2016-04-01

    1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law , no person shall be subject to any penalty...3. Solid Phase Heats of Formation The second of the 2 key performance properties, the solid phase heat of formation, traditionally has been a...salts from density measurements. Inorg Chem. 2002;41:2364. 16. Jenkins HDB, Glasser L. Volume-based thermodynamics : estimations for 2:2 salts. Inorg

  10. Theoretical Study on the High Energy Density Compound Hexanitrohexaazatricyclotetradecanedifuroxan

    Institute of Scientific and Technical Information of China (English)

    QIU Ling; XIAO He-Ming; ZHU Wei-Hua; JU Xue-Hai; GONG Xue-Dong

    2006-01-01

    Density functional theory (DFT) has been employed to study the molecular geometries, electronic structures,infrared (IR) spectra, and thermodynamic properties of the high energy density compound hexanitrohexaazatricyclotetradecanedifuroxan (HHTTD) at the B3LYP/6-31G** level of theory. The calculated results showthattherearefourconformationalisomers (a, β, γ and δ) for HHTTD, and the relative stabilities of four conformers were assessed based on the calculated total energies and the energy-gaps between the frontier molecular orbitals. The computed harmonic vibrational frequencies are in reasonable agreement with the available experimental data. Thermodynamic properties derived from the IR spectra on the basis of statistical thermodynamic principles are linearly correlated with the temperature. Detonation performances were evaluated by using the Kamlet-Jacobsequationsbasedonthecalculated densities and heats of formation. It was found that four HHTTD isomers with the predicted densities of ca. 2 g·cm-3, detonation velocities near 10 km·s-1, and detonation pressures over 45 Gpa, may be novel potential candidates of high energy density materials (HEDM). These results may provide basic information for the molecular designof HEDM.

  11. Theoretical Studies of Possible Synthetic Routes for the High Energy Density Material Td N4: Excited Electronic States

    Science.gov (United States)

    Lee, Timothy J.; Dateo, Christopher E.

    2001-01-01

    Vertical electronic excitation energies for single states have been computed for the high energy density material (HEDM) Td N4 in order to assess possible synthetic routes that originate from excited electronic states of N2 molecules. Several ab initio theoretical approaches have been used, including complete active space self-consistent field (CASSCF), state averaged CASSCF (SA-CASSCF), singles configuration interaction (CIS), CIS with second-order and third-order correlation corrections [CIS(D)) and CIS(3)], and linear response singles and doubles coupled-cluster (LRCCSD), which is the highest level of theory employed. Standard double zeta polarized (DZP) and triple zeta double polarized (TZ2P) one-particle basis sets were used. The CASSCF calculations are found to overestimate the excitation energies, while the SA-CASSCF approach rectifies this error to some extent, but not completely. The accuracy of the CIS calculations varied depending on the particular state, while the CIS(D), CIS(3), and LRCCSD results are in generally good agreement. Based on the LRCCSD calculations, the lowest six excited singlet states are 9.35(l(sup)T1), 10.01(l(sup)T2), 10.04(1(sup)A2), 10.07(1(sup)E), 10.12(2(sup)T1), and 10.42(2(sup)T2) eV above the ground state, respectively. Comparison of these excited state energies with the energies of possible excited states of N2+N2 fragments, leads us to propose that the most likely synthetic route for Td N4 involving this mechanism arises from combination of two bound quintet states of N2.

  12. Density functional theory and multiscale materials modeling

    Indian Academy of Sciences (India)

    Swapan K Ghosh

    2003-01-01

    One of the vital ingredients in the theoretical tools useful in materials modeling at all the length scales of interest is the concept of density. In the microscopic length scale, it is the electron density that has played a major role in providing a deeper understanding of chemical binding in atoms, molecules and solids. In the intermediate mesoscopic length scale, an appropriate picture of the equilibrium and dynamical processes has been obtained through the single particle number density of the constituent atoms or molecules. A wide class of problems involving nanomaterials, interfacial science and soft condensed matter has been addressed using the density based theoretical formalism as well as atomistic simulation in this regime. In the macroscopic length scale, however, matter is usually treated as a continuous medium and a description using local mass density, energy density and other related density functions has been found to be quite appropriate. A unique single unified theoretical framework that emerges through the density concept at these diverse length scales and is applicable to both quantum and classical systems is the so called density functional theory (DFT) which essentially provides a vehicle to project the many-particle picture to a single particle one. Thus, the central equation for quantum DFT is a one-particle Schrödinger-like Kohn–Sham equation, while the same for classical DFT consists of Boltzmann type distributions, both corresponding to a system of noninteracting particles in the field of a density-dependent effective potential. Selected illustrative applications of quantum DFT to microscopic modeling of intermolecular interaction and that of classical DFT to a mesoscopic modeling of soft condensed matter systems are presented.

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

    Indian Academy of Sciences (India)

    Li Xiao-Hong; Zhang Rui-Zhou

    2014-11-01

    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.

  14. The quest for greater chemical energy storage in energetic materials: Grounding expectations

    Science.gov (United States)

    Lindsay, C. Michael; Fajardo, Mario E.

    2017-01-01

    It is well known that the performance of modern energetic materials based on organic chemistry has plateaued, with only ˜ 40% improvements realized over the past half century. This fact has stimulated research on alternative chemical energy storage schemes in various U.S. government funded "High Energy Density Materials" (HEDM) programs since the 1950's. These efforts have examined a wide range of phenomena such as free radical stabilization, metallic hydrogen, metastable helium, polynitrogens, extended molecular solids, nanothermites, and others. In spite of the substantial research investments, significant improvements in energetic material performance have not been forthcoming. This paper discusses the lessons learned in the various HEDM programs, the different degrees of freedom in which to store energy in materials, and the fundamental limitations and orders of magnitude of the energies involved. The discussion focuses almost exclusively on the topic of energy density and only mentions in passing other equally important properties of explosives and propellants such as gas generation and reaction rate.

  15. Size-dependent density of nanoparticles and nanostructured materials

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Karuna Kar, E-mail: nanda@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore 12 (India)

    2012-10-01

    We discuss the size-dependent density of nanoparticles and nanostructured materials keeping the recent experimental results in mind. The density is predicted to increase with decreasing size for nanoparticles but it can decrease with size for nanostructured materials that corroborates the experimental results reported in the literature. -- Highlights: ► Density of nanoparticles depends mainly on the size-dependent lattice parameter. ► Density is predicted to increase with decreasing size for nanoparticles. ► Density decreases with size for nanostructured materials.

  16. Critical current densities in superconducting materials

    Indian Academy of Sciences (India)

    P Chaddah

    2003-02-01

    We discuss recent research in the area of critical current densities $(J_C)$ in superconductors. This shall cover recent work on newly discovered superconductors, as well as on the magnetic-field dependence of $J_C$.

  17. Theoretical studies on the heats of formation, densities, and detonation properties of substituted s-tetrazine compounds.

    Science.gov (United States)

    Zhou, Yang; Long, XinPing; Shu, YuanJie

    2010-05-01

    Substituted s-tetrazine compounds were designed and investigated in order to find comprehensive relationships between the structures and performances of high-nitrogen energetic compounds. Density functional theory (DFT) was used to predict the optimized geometries, electronic structures, heats of formation and densities, and the detonation properties were evaluated by using the VLW equation of state (EOS). Calculation results show that there are good linear relationships between heats of formation, densities, detonation properties and the number of N atom in all designed high-nitrogen compounds. Furthermore, several designed high-nitrogen compounds show good detonation velocities and pressures compared with octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX), making them potential candidates for high-energy-density materials (HEDM).

  18. Density functional theory in materials science.

    Science.gov (United States)

    Neugebauer, Jörg; Hickel, Tilmann

    2013-09-01

    Materials science is a highly interdisciplinary field. It is devoted to the understanding of the relationship between (a) fundamental physical and chemical properties governing processes at the atomistic scale with (b) typically macroscopic properties required of materials in engineering applications. For many materials, this relationship is not only determined by chemical composition, but strongly governed by microstructure. The latter is a consequence of carefully selected process conditions (e.g., mechanical forming and annealing in metallurgy or epitaxial growth in semiconductor technology). A key task of computational materials science is to unravel the often hidden composition-structure-property relationships using computational techniques. The present paper does not aim to give a complete review of all aspects of materials science. Rather, we will present the key concepts underlying the computation of selected material properties and discuss the major classes of materials to which they are applied. Specifically, our focus will be on methods used to describe single or polycrystalline bulk materials of semiconductor, metal or ceramic form.

  19. MATERIAL COMPOSITIONS AND NUMBER DENSITIES FOR NEUTRONICS CALCULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    D. A. Thomas

    1996-01-02

    The purpose of this analysis is to calculate the number densities and isotopic weight percentages of the standard materials to be used in the neutronics (criticality and radiation shielding) evaluations by the Waste Package Development Department. The objective of this analysis is to provide material number density information which can be referenced by future neutronics design analyses, such as for those supporting the Conceptual Design Report.

  20. Separation of colloidal two dimensional materials by density gradient ultracentrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Kuang, Yun; Song, Sha [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Huang, Jinyang, E-mail: huangjy@mail.buct.edu.cn [Department of Mathematics, College of Science, Beijing University of Chemical Technology, Beijing 100029 (China); Sun, Xiaoming, E-mail: sunxm@mail.buct.edu.cn [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2015-04-15

    Two-dimensional (2D) materials have been made through various approaches but obtaining monodispersed simply by synthesis optimization gained little success, which highlighted the need for introducing nanoseparation methods. Density gradient ultracentrifugation method has emerged as a versatile and scalable method for sorting colloidal 2D nanomaterials. Isopycnic separation was applied on thickness-dependent separation of graphene nanosheets. And rate-zonal separation, as a more versatile separation method, demonstrated its capability in sorting nanosheets of chemically modified single layered graphene, layered double hydroxide, and even metallic Ag. Establishing such density gradient ultracentrifugation method not only achieves monodispersed nanosheets and provides new opportunities for investigation on size dependent properties of 2D materials, but also makes the surface modification possible by introducing “reaction zones” during sedimentation of the colloids. - Graphical abstract: Two-dimensional (2D) materials have been made through various approaches but obtaining monodispersed simply by synthesis optimization gained little success, which highlighted the need for introducing nanoseparation methods. Density gradient ultracentrifugation method has emerged as a versatile and scalable method for sorting colloidal 2D nanomaterials according to their size of thickness difference. Establishing such density gradient ultracentrifugation method not only achieves monodispersed nanosheets and provides new opportunities for investigation on size dependent properties of 2D materials, but also makes the surface modification possible by introducing “reaction zones” during sedimentation of the colloids. - Highlights: • Density gradient ultracentrifugation was applied on size separation of 2D material. • Isopycnic separation was applied on separation of low density materials. • Rate-zonal separation was applied on separation of large density materials. • Size

  1. Proceedings of the High Energy Density Matter (HEDM) Conference Held in Rosslyn, Virginia on 12-13 May 1987,

    Science.gov (United States)

    1987-09-01

    laser initiated decomposition, IR, UV-Vis, ultraviolet, visible, spectroscopy, H 30, N 202, dinitrogen dioxide , CO, carbon monoxide, CH, high spin...asymmetric dinitrogen dioxide (a-N202), is an analogue of fluorine azide (FN3) and is predicted to be a cryogenic solid. Benard reported that FN3 can be...DETECTION OF H4 * PHOTODISSOCIATION TO FORM H2(B) - A 500 nm - DETECT H2 (B) EMISSION WITH PMT - FLASHLAMP PHOTOLYSIS, X = 200 TO 800 nm - LASER

  2. Proceedings of the High Energy Density Matter (HEDM) Conference Held in New Orleans, Louisiana on 12-15 March 1989

    Science.gov (United States)

    1989-07-01

    distance in a planar arrangement of ArH3 , with the argon directly above the apical hydrogen. Matcha and 3, Milleur’ confined their calculations for...Phys. .11, 27 (1976). 7. W. J. Stevens, H-. Basch, and M. Krauss, J. Chem. Phys. il 6026 (1984). 8. R. L. Matcha , and Mac B. Milleur, J. Chem. Phys. f2

  3. Molecular Design of Low-Density Multifunctional Hybrid Materials

    Science.gov (United States)

    2016-01-01

    Structure -Property Relationships of Hybrid Mixed Oxide Organic - Inorganic Films for Multilayer Adhesive Bonding”, MRS 2012 Spring Meeting, San Francisco...AVAILABILITY STATEMENT No distribution limitation. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Low-density hybrid materials, which contain organic and... hybrid materials, which contain organic and inorganic molecular components, can be engineered over a wide range of length scales to exhibit unique

  4. Recommended reference materials for realization of physicochemical properties density

    CERN Document Server

    Herington, E F G

    1976-01-01

    This book first presents the nomenclature and units used in the determination of densities of liquids and solids, followed by a general description of the apparatus and the methods used in the measurement of density, with particular reference to the pycnometric, hydrostatic weighing, magnetic float, and temperature flotation methods. The use of water as a density reference material is then explained, focusing on the isotopic composition of Standard Mean Ocean Water (SMOW) and the absolute density of SMOW as a function of temperature. Problems due to the effect of pressure and dissolved gases o

  5. Magnetocaloric Materials and the Optimization of Cooling Power Density

    Science.gov (United States)

    Wikus, Patrick; Canavan, Edgar; Heine, Sarah Trowbridge; Matsumoto, Koichi; Numazawa, Takenori

    2014-01-01

    The magnetocaloric effect is the thermal response of a material to an external magnetic field. This manuscript focuses on the physics and the properties of materials which are commonly used for magnetic refrigeration at cryogenic temperatures. After a brief overview of the magnetocaloric effect and associated thermodynamics, typical requirements on refrigerants are discussed from a standpoint of cooling power density optimization. Finally, a compilation of the most important properties of several common magnetocaloric materials is presented.

  6. High density data storage principle, technology, and materials

    CERN Document Server

    Zhu, Daoben

    2009-01-01

    The explosive increase in information and the miniaturization of electronic devices demand new recording technologies and materials that combine high density, fast response, long retention time and rewriting capability. As predicted, the current silicon-based computer circuits are reaching their physical limits. Further miniaturization of the electronic components and increase in data storage density are vital for the next generation of IT equipment such as ultra high-speed mobile computing, communication devices and sophisticated sensors. This original book presents a comprehensive introduction to the significant research achievements on high-density data storage from the aspects of recording mechanisms, materials and fabrication technologies, which are promising for overcoming the physical limits of current data storage systems. The book serves as an useful guide for the development of optimized materials, technologies and device structures for future information storage, and will lead readers to the fascin...

  7. The density matrix method in photonic bandgap and antiferromagnetic materials

    Science.gov (United States)

    Barrie, Scott B.

    In this thesis, a theory for dispersive polaritonic bandgap (DPBG) and photonic bandgap (PBG) materials is developed. An ensemble of multi-level nanoparticles, such as non-interacting two-, three- and four-level atoms doped in DPBG and PBG materials is considered. The optical properties of these materials such as spontaneous emission, line broadening, fluorescence and narrowing of the natural linewidth have been studied using the density matrix method. Numerical simulations for these properties have been performed for the DPBG materials SiC and InAs, and for a PBG material with a 20 percent gap-to-midgap ratio. When a three-level nanoparticle is doped into a DPBG material, it is predicted that one or two bound states exist when one or both resonance energies, respectively, lie in the bandgap. It is shown when a resonance energy lies below the bandgap, its spectral density peak weakens and broadens as the resonance energy increases to the lower band edge. For the first time it is predicted that when a nanoparticle's resonance energy lies above the bandgap, its spectral density peak weakens and broadens as the resonance energy increases. A relation is also found between spectral structure and gap-to-midgap ratios. The dressed states of a two-level atom doped into a DPBG material under the influence of an intense monochromatic laser field are examined. The splitting of the dressed state energies is calculated, and it is predicted that the splitting depends on the polariton density of states and the Rabi frequency of laser field. The fluoresence is also examined, and for the first time two distinct control processes are found for the transition from one peak to three peaks. It was previously known that the Rabi frequency controlled the Stark effect, but this thesis predicts that the local of the peak with respect to the optical bandgap can cause a transition from one to three peaks even with a weak Rabi frequency. The transient linewidth narrowing of PBG crystal

  8. Laser Propagation in Nanostructured Ultra-Low-Density Materials

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, K. B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Colvin, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Yogo, A [Osaka Univ. (Japan). Inst. of Laser Engineering; Kemp, G. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Matsukuma, H. [Osaka Univ. (Japan). Inst. of Laser Engineering; Tanaka, N. [Osaka Univ. (Japan). Inst. of Laser Engineering; Zhang, Z. [Osaka Univ. (Japan). Inst. of Laser Engineering; Koga, K. [Osaka Univ. (Japan). Inst. of Laser Engineering; Tosaki, S. [Osaka Univ. (Japan). Inst. of Laser Engineering; Nishimura, H. [Osaka Univ. (Japan). Inst. of Laser Engineering

    2016-03-15

    The nanostructure of very-low-density aerogels (< 10 mg/cm3) affects the laser heating and propagation of the subsequent heat front. Simulations treat these materials as an atomistic medium without any structure differentiating between near-solid-density material and voids. Thus, simulations fail to predict the effects of the aerogel’s physical micro or nanostructure on the laser-matter interaction. We have designed an experiment using the GEKKO XII laser and ILE diagnostics to characterize the ionization-wave propagation and x-ray yield from aerogel and mass-matched gaseous targets as the laser passes through each. By design, the gas and aerogel targets will have identical densities and identical effective ionization states.

  9. Density Functional Theory and Materials Modeling at Atomistic Length Scales

    Directory of Open Access Journals (Sweden)

    Swapan K. Ghosh

    2002-04-01

    Full Text Available Abstract: We discuss the basic concepts of density functional theory (DFT as applied to materials modeling in the microscopic, mesoscopic and macroscopic length scales. The picture that emerges is that of a single unified framework for the study of both quantum and classical systems. While for quantum DFT, the central equation is a one-particle Schrodinger-like Kohn-Sham equation, the classical DFT consists of Boltzmann type distributions, both corresponding to a system of noninteracting particles in the field of a density-dependent effective potential, the exact functional form of which is unknown. One therefore approximates the exchange-correlation potential for quantum systems and the excess free energy density functional or the direct correlation functions for classical systems. Illustrative applications of quantum DFT to microscopic modeling of molecular interaction and that of classical DFT to a mesoscopic modeling of soft condensed matter systems are highlighted.

  10. Effective atomic numbers and electron density of dosimetric material

    Directory of Open Access Journals (Sweden)

    Kaginelli S

    2009-01-01

    Full Text Available A novel method for determination of mass attenuation coefficient of x-rays employing NaI (Tl detector system and radioactive sources is described.in this paper. A rigid geometry arrangement and gating of the spectrometer at FWHM position and selection of absorber foils are all done following detailed investigation, to minimize the effect of small angle scattering and multiple scattering on the mass attenuation coefficient, m/r, value. Firstly, for standardization purposes the mass attenuation coefficients of elemental foils such as Aluminum, Copper, Molybdenum, Tantalum and Lead are measured and then, this method is utilized for dosimetric interested material (sulfates. The experimental mass attenuation coefficient values are compared with the theoretical values to find good agreement between the theory and experiment within one to two per cent. The effective atomic numbers of the biological substitute material are calculated by sum rule and from the graph. The electron density of dosimetric material is calculated using the effective atomic number. The study has discussed in detail the attenuation coefficient, effective atomic number and electron density of dosimetric material/biological substitutes.

  11. Electromagnetic field energy density in homogeneous negative index materials.

    Science.gov (United States)

    Shivanand; Webb, Kevin J

    2012-05-07

    An exact separation of both electric and magnetic energies into stored and lost energies is shown to be possible in the special case when the wave impedance is independent of frequency. A general expression for the electromagnetic energy density in such a dispersive medium having a negative refractive index is shown to be accurate in comparison with numerical results. Using an example metamaterial response that provides a negative refractive index, it is shown that negative time-averaged stored energy can occur. The physical meaning of this negative energy is explained as the energy temporarily borrowed by the field from the material. This observation for negative index materials is of interest when approaching properties for a perfect lens. In the broader context, the observation of negative stored energy is of consequence in the study of dispersive materials.

  12. High power densities from high-temperature material interactions

    Energy Technology Data Exchange (ETDEWEB)

    Morris, J.F.

    1981-01-01

    Thermionic energy conversion (TEC) and metallic-fluid heat pipes (MFHPs) offer important and unique advantages in terrestrial and space energy processing. And they are well suited to serve together synergistically. TEC and MFHPs operate through working-fluid vaporization, condensation cycles that accept great thermal power densities at high temperatures. TEC and MFHPs have apparently simple, isolated performance mechanisms that are somewhat similar. And they also have obviously difficult, complected material problems that again are somewhat similar. Intensive investigation reveals that aspects of their operating cycles and material problems tend to merge: high-temperature material effects determine the level and lifetime of performance. Simplified equations verify the preceding statement for TEC and MFHPs. Material properties and interactions exert primary influences on operational effectiveness. And thermophysicochemical stabilities dictate operating temperatures which regulate the thermoemissive currents of TEC and the vaporization flow rates of MFHPs. Major high-temperature material problems of TEC and MFHPs have been solved. These solutions lead to productive, cost-effective applications of current TEC and MFHPs - and point to significant improvements with anticipated technological gains.

  13. Advanced Porous Coating for Low-Density Ceramic Insulation Materials

    Science.gov (United States)

    Leiser, Daniel B.; Churchward, Rex; Katvala, Victor; Stewart, David; Balter, Aliza

    1988-01-01

    The need for improved coatings on low-density reusable surface insulation (RSI) materials used on the space shuttle has stimulated research into developing tougher coatings. The processing of a new porous composite "coating" for RST called toughened unipiece fibrous insulation Is discussed. Characteristics including performance in a simulated high-speed atmospheric entry, morphological structure before and after this exposure, resistance to Impact, and thermal response to a typical heat pulse are described. It is shown that this coating has improved impact resistance while maintaining optical and thermal properties comparable to the previously available reaction-cured glass coating.

  14. Image density property of optical information recording microcapsule material

    Science.gov (United States)

    Lai, Weidong; Li, Xiaowei; Li, Xinzheng; Fu, Guangsheng

    2009-05-01

    The microcapsules can act as novel optical functional material in which the optical recording substance such as color-forming substance, photoinitiator and prepolymer are encapsulated. In this paper, the microcapsules with average particle diameter of 300nm are prepared with interfacial polymerization method. The optical responding character of the microcapsule is analyzed based on IR spectra and image density technique. Results show that the microcapsule material encapsulated prepolymer TMPTA and photoinitiator Irgacure-ITX, TPO has thermal phase-change at 140°C, at which the penetrability of the microcapsule has the highest efficiency. With the increase of exposure time, the reduction in absorption intensities of the prepolymer TMPTA are observed at 1635cm-1 of C=C stretching and 898cm-1 of C-H stretching on the C=C molecular bond. Such a result can be ascribed to the double bond cleavage process of the prepolymer TMPTA is initiated by the optical-exposed photoinitiator, and superpolymer network is formed. The image density contrast between the unexposed and exposed microcapsule is enhanced with exposure time increased.

  15. Microstructural characterization of pressed HMX material sets at differing densities

    Science.gov (United States)

    Molek, C. D.; Welle, E. J.; Wixom, R. R.; Ritchey, M. B.; Samuels, P.; Horie, Y.

    2017-01-01

    The detonation physics community has embraced the idea that initiation of high explosives (HE) proceeds from an ignition event through subsequent growth to steady detonation. A weakness of all the commonly used ignition and growth models is the microstructural characteristics of the HE are not explicitly incorporated in their ignition and growth terms. This is the case in spite of a demonstrated, but not well-understood, empirical link between particle morphology and initiation of HE. Morphological effects have been parametrically studied in many ways, the majority of efforts focus on establishing a tie between bulk powder metrics and initiation of the pressed beds. More recently, there has been a shift toward characterizing the microstructure of pressed beds in order to understand the underlying mechanisms governing initiation behavior. In this work, we have characterized the microstructures of two HMX classes pressed at three densities using ion bombardment techniques. We find more significant compaction associated with the larger crystalline material - Class 3 - than the smaller fluid energy milled material. The Class 3 material exhibits evidence of crystal cracking. Finally, we discuss this evidence and our attempt to correlate microstructural features to observed changes in continuum level initiation behavior.

  16. Applications of density functional theory in materials science and engineering

    Science.gov (United States)

    Alvarado, Manuel, Jr.

    Density Functional Theory (DFT) is a powerful tool that can be used to model various systems in materials science. Our research applies DFT to two problems of interest. First, an organic/inorganic complex dye system known as a Mayan pigment is modeled to determine chemical binding sites, verifying each model with physical data such as UV/Vis spectra. Preliminary studies on palygorskite-based mayan pigments (mayacrom blue, mayacrom purple) show excellent agreement with experimental studies when using a dimer dye geometry binding with tetrahedrally-coordinated aluminum impurity sites in palygorksite. This approach is applied to a sepiolite-based organic/inorganic dye system using thioindigo attached to a tetrahedral aluminum impurity site with an additional aluminum impurity site in close proximity to the binding site. As a second application of DFT, various grain orientations in beta-Sn are modeled under imposed strains in order to calculate elastic properties of this system. These calculations are intended to clarify discrepancies in published, experimental crystal compliance values.

  17. Tensile Behavior of Low Density Thermally Bonded Nonwoven Material

    Directory of Open Access Journals (Sweden)

    Xiaonan Hou

    2009-06-01

    Full Text Available A discontinuous and non-uniform microstructure of alow-density thermally bonded nonwoven materialdisplays in a complicated and unstable tensilebehavior. This paper reports uniaxial tensile tests of alow density thermally bonded nonwoven toinvestigate the effect of the specimen size and shapefactor, as well as the cyclic tensile loading conditionsemployed to investigate the deformational behaviorand performance of the nonwoven at differentloading stages. The experimental data are comparedwith results of microscopic image analysis and FEmodels.

  18. The role of adequate reference materials in density measurements in hemodialysis

    Science.gov (United States)

    Furtado, A.; Moutinho, J.; Moura, S.; Oliveira, F.; Filipe, E.

    2015-02-01

    In hemodialysis, oscillation-type density meters are used to measure the density of the acid component of the dialysate solutions used in the treatment of kidney patients. An incorrect density determination of this solution used in hemodialysis treatments can cause several and adverse events to patients. Therefore, despite the Fresenius Medical Care (FME) tight control of the density meters calibration results, this study shows the benefits of mimic the matrix usually measured to produce suitable reference materials for the density meter calibrations.

  19. Modelling density segregation in flowing bidisperse granular materials

    Science.gov (United States)

    Xiao, Hongyi; Umbanhowar, Paul B.; Ottino, Julio M.; Lueptow, Richard M.

    2016-07-01

    Preventing segregation in flowing granular mixtures is an ongoing challenge for industrial processes that involve the handling of bulk solids. A recent continuum-based modelling approach accurately predicts spatial concentration fields in a variety of flow geometries for mixtures varying in particle size. This approach captures the interplay between advection, diffusion and segregation using kinematic information obtained from experiments and/or discrete element method (DEM) simulations combined with an empirically determined relation for the segregation velocity. Here, we extend the model to include density-driven segregation, thereby validating the approach for the two important cases of practical interest. DEM simulations of density bidisperse flows of mono-sized particles in a quasi-two-dimensional-bounded heap were performed to determine the dependence of the density-driven segregation velocity on local shear rate and particle concentration. The model yields theoretical predictions of segregation patterns that quantitatively match the DEM simulations over a range of density ratios and flow rates. Matching experiments reproduce the segregation patterns and quantitative segregation profiles obtained in both the simulations and the model, thereby demonstrating that the modelling approach captures the essential physics of density-driven segregation in granular heap flow.

  20. Achieving tunable sensitivity in composite high-energy density materials

    Science.gov (United States)

    Kuklja, Maija M.; Tsyshevsky, Roman V.; Rashkeev, Sergey

    2017-01-01

    Laser irradiation provides a unique opportunity for selective, predictive, and controlled initiation of energetic materials. We propose a consistent micro-scale mechanism of photoexcitation at the interface, formed by a molecular energetic material and a metal oxide. A specific PETN-MgO model composite is used to illustrate and explain seemingly puzzling experiments on selective laser initiation of energetic materials, which reported that the presence of metal oxide additives triggered the photoinitiation by an unusually low energy. We suggest that PETN photodecomposition is catalyzed by oxygen vacancies (F0 centers) at the MgO surface. The proposed model suggests ways to tune sensitivity of energetic molecular materials to photoinitiation. Our quantum-chemical calculations suggest that the structural point defects (e.g., oxygen vacancies) strongly interact with the molecular material (e.g., adsorbed energetic molecules) by inducing a charge transfer at the interface and hence play an imperative role in governing both energy absorption and energy release in the system. Our approach and conclusions provide a solid basis for novel design of energetic interfaces with desired properties and offers a new perspective in the field of explosive materials and devices.

  1. Relative Density of Backfilled Soil Material around Monopiles for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, Søren Peder Hyldal; Ibsen, Lars Bo; Frigaard, Peter

    2012-01-01

    The relative density of backfilled soil material around offshore monopiles is assessed through experimental testing in the Large Wave Channel (GWK) of the Coastal Research Centre (FZK) in Hannover. The relative density of the backfill material was found to vary between 65 and 80 %. The dependency...... of the relative density of backfill on the maximum pile bending moment is assessed through three-dimensional numerical modeling of a monopile foundation located at the offshore wind farm at Horns Reef, Denmark....

  2. Thixoinfiltration: a new approach to produce cellular and other low density metallic materials

    OpenAIRE

    M.H. Robert; A.F. Jorge; F. Gatamorta; R. R. SILVA

    2010-01-01

    Purpose: the work presents an innovative approach for the production of cellular metallic materials as well as low density metal matrix composites, by using thixoforming techniques; thixotropic semisolid metal is infiltrated into removable and non-removable space holder preforms. Different kinds of preforms are tested to obtain open cell material (sponges), syntactic foams and low density composites. Products are evaluated concerning relative density and mechanical behavior under compressive ...

  3. Density-Driven Currents and Deposition of Fine Materials

    DEFF Research Database (Denmark)

    Saremi, Sina

    Dredging is a key element in river, ports, coastal and offshore development. In general dredging is conducted for excavation at the river,lake or seabed, relocation of the material, maintenance of the navigation channels, mining underwater deposits, land reclamation or cleaning up the environment....... Dredging activities always make changes to the environment, such as alteration of the coastal or river morphology, currents and wave climates, and water quality. Such changes may be considered improving or degrading to the environment. The type of material being dredged, type of the dredging equipment...... and type of sediments change along and into the seabed. Variations in the material entering the hopper have been studied by assuming fluctuating inflow concentrations. The fluctuations impose a mean net change on the overflow concentrations. In the third part of this study, the above described CFD model...

  4. Materials for high-density electronic packaging and interconnection

    Science.gov (United States)

    1990-01-01

    Electronic packaging and interconnections are the elements that today limit the ultimate performance of advanced electronic systems. Materials in use today and those becoming available are critically examined to ascertain what actions are needed for U.S. industry to compete favorably in the world market for advanced electronics. Materials and processes are discussed in terms of the final properties achievable and systems design compatibility. Weak points in the domestic industrial capability, including technical, industrial philosophy, and political, are identified. Recommendations are presented for actions that could help U.S. industry regain its former leadership position in advanced semiconductor systems production.

  5. Progress in materials and technologies for ultrahigh density data storage

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    With the development of information superhighway, nanometer-scale data storage has been proposed and attracted great interest in recent years. This article reviews the research achievements in this field, and especially focuses on the materials for data recording by using an atomic force microscope (AFM) and scanning tunneling microscope (STM).

  6. A Method for Determining Bulk Density, Material Density, and Porosity of Melter Feed During Nuclear Waste Vitrification

    Energy Technology Data Exchange (ETDEWEB)

    Hilliard, Zachary J.; Hrma, Pavel R.

    2016-01-31

    Abstract Glass making efficiency largely depends on heat transfer to reacting glass batch (melter feed), which in turn is influenced by the bulk density (ρb) and porosity (Φ) as functions of temperature (T). Neither b(T) nor Φ(T) functions are readily accessible to direct measurement, but they can be determined based on monitoring the profile area of heated glass batch pellets and material density of batches quenched at various stages of conversion via pycnometry. For the determination of Φb, the bulk volume must be calculated as a function of temperature. This is done via a program constructed in MATLAB which takes an image of a pellet profile at a given temperature and calculates the volume of said pellet. The quenched density measured by pycnometry must be converted to the density at heat treatment temperature. This is done by taking into account the volume change due to thermal expansion/contraction.

  7. Proceedings of the High Energy Density Matter (HEDM) Contractor’s Conference Held in Woods Hole, Massachusetts on 6-8 June 1993

    Science.gov (United States)

    1993-11-01

    and L. G. M. Petterson , J. Chem. Phys. 89 5747 (1988). 23. L. B. Knight, Jr., S. T. Corbranchi, J. 0. Herlong, and C. A. Arrington, J. Chem. Phys. 92...vusi. awrpao awlmsa The uJ@e Alin fta he swge* pqwemt do ablatd plam.e l puls prmesn (S), and that obtauned with breakdown pulses only (SO). Bot S and S

  8. Nuclear isomers as ultra-high-energy-density materials

    Science.gov (United States)

    Poppe, C. H.; Weiss, M. S.; Anderson, J. D.

    1992-09-01

    A major energy advance could result if the enormous potential of nuclear energy storage could be tapped without the penalty of radioactive by-products. Recent research has uncovered a new method for nuclear energy storage with high energy density and no residual radioactivity. Nuclear isomers are metastable states of atomic nuclei which release their energy in a prompt burst of electromagnetic radiation; in many cases the product remaining after decay of isomer is stable and no activity is produced by the electromagnetic decay. Two kinds of nuclear isomers are known: spin isomers and shape isomers. The former lacks a release mechanism. Theory has predicted the existence of shape isomers in the mass range around mercury and gold where decay by fission is prohibited. Experiments on the existence of fissionless shape isomers have resulted in evidence for 27 different shape isomers in isotopes of mercury, lead, and thallium. Three potential candidates for release mechanisms have been identified to date: neutron catalysis (Hf- 178), laser-electron-nuclear coupling (Th-229), and Stark-shift-induced mixing (speculative). Ways of producing nonfissioning shape isomers are discussed.

  9. Supersonic Propagation of Heat Waves in Low Density Heavy Material

    Institute of Scientific and Technical Information of China (English)

    Jiang Shaoen; Zhang Wenhai; Yi Rongqing; Cui Yanli; Chen Jiusen; Xu Yan; Ding Yongkun; Lai Dongxian; Zheng Zhijian; Huang Yikiang; Li Jinghong; Sun Kexu; Hu Xin

    2005-01-01

    The propagation of a supersonic heat-wave through copper-doped foam with a density of 50 mg/cm3 was experimentally investigated. The wave is driven by 140 eV Holhraum radiations generated in a cylindrical gold cavity heated by a 2 k J, 1ns laser pulse (0.35 μm). The delayed breakout time of the radiation waves from the rear side of the foam is measured by a threechromatic streaked x-ray spectrometer (TCS) consisting of a set of three-imaging pinholes and an array of three transmission gratings coupled with an x-ray streak camera (XSC). With one shot,simultaneous measurements of the delays of the drive source and the radiation with two different energies (210 eV, 840 eV) through the foam have been made for the first time. The experimental results indicate that the time delays vary with photon energies. The radiation with an energy of 210 eV propagates at a lower velocity. The radiating heat wave propagates with a velocity that is larger than the sound speed. Using TGS, the transmitting spectrum was measured, and then lower limit of the optical depth which is more than 1, was obtained. The experimental data were in agreement with numerical simulations.

  10. Theoretical studies on densities, stability and detonation properties of 2D polymeric complexes Cu(DAT)₂Cl₂ and its new analogues Zn(DAT)₂Cl₂.

    Science.gov (United States)

    Shu, Yuanjie; Li, Huarong; Gao, Shijie; Xiong, Ying

    2013-04-01

    A novel environmentally friendly octahedrally coordinated 2D polymeric complexes bis(1,5-diaminotetrazole) -dichlorozinc(II) (Zn(DAT)2Cl2) was first designed based on the the crystal data of bis(1,5-diaminotetrazole)- dichlorocopper(II) (Cu(DAT)2Cl2). Density functional theory (DFT) was used to predict the optimized geometries at TPSSTPSS/6-311G(d, p) level. Densities and detonation properties were evaluated using the electron cloud enclosed volume and VLW equation of state (VLW EOS), respectively. Calculation results show that the density of Zn(DAT)2Cl2 (2.117 g · cm(-1)) is a bit more than that of Cu(DAT)2Cl2 (2.106 g · cm(-1)). The calculated high positive heat of formation (HOF) predicts that the stabilities of the title compounds decrease in the order Zn(DAT)2Cl2 > Cu(DAT)2Cl2, which agrees with the result of bond dissociation energies (BDE). Even though they have the same molecule structures, their first scission steps are different. Furthermore, the title two compounds show good detonation velocities and pressures compared with that of bis-(5-nitro-2H-tetrazolato-N (2)) tetraamminecobalt(III) perchlorates (BNCP), and they are potential candidates for high-energy-density materials (HEDM).

  11. Advanced Cathode Material For High Energy Density Lithium-Batteries Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced cathode materials having high red-ox potential and high specific capacity offer great promise to the development of high energy density lithium-based...

  12. Quantifying Density, Water Adsorption and Equilibration Properties of Wind Tunnel Materials

    Science.gov (United States)

    Yu, Xinting; Horst, Sarah; He, Chao; Bridges, Nathan; Burr, Devon M.; Sebree, Joshua

    2016-10-01

    Aeolian processes are found on various planetary bodies including Earth, Venus, Mars, Titan, Triton, Pluto, and Comet 67P. Wind tunnels can simulate aeolian processes under different planetary parameters, with the robustness of results relying on experimental conditions and understanding of experimental materials. Threshold wind speed, the minimum wind speed to initiate saltation, is one parameter that can be investigated in wind tunnels. Liquid water adsorbed on wind tunnel materials could greatly enhance the threshold wind speed by increasing the interparticle force, density, and effective size of particles. Previous studies have shown that this effect could increase the threshold by 100% by putting 0.3-0.6% of water into typical dry quartz sand (Fecan et al. 1998). In order to simulate the weight of particles on other planetary bodies where gravity is significantly lower than on Earth, low-density materials are used in planetary wind tunnels, including walnut shells, activated charcoal, iced tea, and instant coffee.We first quantified the densities for all wind tunnel materials using a pycnometer and updated the density for low-density materials (e.g., walnut shells have density of 1.4 g/cm3 instead of 1.1 g/cm3 in the literature (Greeley et al. 1980)). Then we present a set of measurements that quantify water adsorption for both low and high-density materials (sand, basalt, and chromite). We first measured the water content and equilibration timescales for the materials through gravimetric measurements. We found low-density materials tend to have much more water (>5%) compared to high-density materials ( 6 hrs) compared to high-density materials (10-50 minutes). Since only water adsorbed on the particle surface would change the interparticle force, we then separate the surface and internal water using thermo-gravimetric analysis, and found that >80% of the water is still on the surface. Thus we assume water adsorption for low-density materials could greatly

  13. Bulk Density Adjustment of Resin-Based Equivalent Material for Geomechanical Model Test

    Directory of Open Access Journals (Sweden)

    Pengxian Fan

    2015-01-01

    Full Text Available An equivalent material is of significance to the simulation of prototype rock in geomechanical model test. Researchers attempt to ensure that the bulk density of equivalent material is equal to that of prototype rock. In this work, barite sand was used to increase the bulk density of a resin-based equivalent material. The variation law of the bulk density was revealed in the simulation of a prototype rock of a different bulk density. Over 300 specimens were made for uniaxial compression test. Test results indicated that the substitution of quartz sand by barite sand had no apparent influence on the uniaxial compressive strength and elastic modulus of the specimens but can increase the bulk density, according to the proportional coarse aggregate content. An ideal linearity was found in the relationship between the barite sand substitution ratio and the bulk density. The relationship between the bulk density and the usage of coarse aggregate and barite sand was also presented. The test results provided an insight into the bulk density adjustment of resin-based equivalent materials.

  14. Effect of density on forward and upward smoldering combustion of cellulosic material

    Science.gov (United States)

    Veronica, Sherly; Putri, R. H.; Fitriani, F.; Ramadhan, M. L.; Riki, M.; Reynaldo, S.; Imran, F. A.; Nugroho, Yulianto S.

    2017-03-01

    Smoldering is a slow, flameless and the most persistent type of combustion. Wildland fire or ground fire is an example of smoldering combustion which has become one of the most important issue in Indonesia and no effective solution has been found to solve this phenomenon yet. The organic materials contained in peatland can potentially become a flammable fuel with the presence of a trigger for wildland fire. In this experimental work tobacco material was used to study smoldering phenomenon. The relation between material density with temperature distribution and mass loss rate are conducted in the experiment. The transmissivity of the smoke produced by the smoldering combustion will also be analyzed. Experiments are carried out for the material density ranging from 0.12 - 0.2 g/cm3. The result showed that smoldering combustion are affected by density, due to the allowance of airflow and heat propagation. The result showed that material bed with the lowest density of 0.12 g/cm3 has the slowest smoldering velocity and mass loss rate while the material bed with the highest density of 0.2 g/cm3 has the fastest smoldering velocity and mass loss rate. The smoke took a longer period time to reach the bed surface at higher bed density.

  15. An algorithm for noise correction of dual-energy computed tomography material density images.

    Science.gov (United States)

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

    2015-01-01

    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.

  16. The Many Faces of FOX-7: A Precursor to High-Performance Energetic Materials.

    Science.gov (United States)

    Gao, Haixiang; Shreeve, Jean'ne M

    2015-05-18

    New derivatives of 1,1-diamino-2, 2-dinitroethene (FOX-7) are reported. These highly oxygen- and nitrogen-rich compounds were fully characterized using IR and multinuclear NMR spectroscopy, elemental analysis (EA), and differential scanning calorimetry (DSC). X-ray structure determination of (E)-1,2-bis{(E)-2-chloro-1-(chloroimino)-2,2-dinitroethyl}diazene) (10), N1, N2-dichloro-1, 2-diazenedicarboximidamide (11), and (E,E)-N,N'-1,2-ethanediylidenebis(2, 2-dinitro-2-chloro-ethanamine) (12) was helpful in their characterization. Heats of formation (HOF) were calculated (Gaussian 03) and combined with experimental densities to estimate the detonation velocities (D) and pressures (P) of the high-energy-density materials (HEDMs) (EXPLO5, v6.01). The compounds exhibit good thermal stability, high density, positive HOF, acceptable oxygen balances, and excellent detonation properties, which often are superior to that of 1,3,5-trinitroperhydro-1,3,5-triazine (RDX). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Looking for high energy density compounds applicable for propellant among the derivatives of DPO with -N3, -ONO2, and -NNO2 groups.

    Science.gov (United States)

    Wang, Gui-Xiang; Gong, Xue-Dong; Liu, Yan; Du, Hong-Chen; Xu, Xiao-Juan; Xiao, He-Ming

    2011-04-15

    The derivatives of DPO (2,5-dipicryl-1,3,4-oxadiazole) are optimized to obtain their molecular geometries and electronic structures at the DFT-B3LYP/6-31G* level. The bond length is focused to primarily predict thermal stability and the pyrolysis mechanism of the title compounds. Detonation properties are evaluated using the modified Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that there are good linear relationships between density, detonation velocity, detonation pressure, and the number of azido, nitrate, and nitramine groups. According to the largest exothermic principle, the relative specific impulse is investigated by calculating the enthalpy of combustion (ΔH(comb)) and the total heat capacity (C(p,gases)). It is found that the introduction of -N(3), -ONO(2), and -NNO(2) groups could increase the specific impulses and II-4, II-5, and III-5 are potential candidates for High Energy Density Materials (HEDMs). The effect of the azido, nitrate, and nitramine groups on the structure and the properties is discussed.

  18. A study on photon attenuation coefficients of different wood materials with different densities

    Science.gov (United States)

    Saritha, B.; Nageswara Rao, A. S.

    2015-12-01

    A study on the variation of linear attenuation coefficients with the densities of the wood samples is under taken. The soft wood and hard wood samples were collected from the forest area of Pakal in Warangal district. The linear and mass attenuation coefficients are measured using gamma ray spectrometry based on NaI (Tl) scintillation detector with energies of 662 KeV and 59.5 KeV respectively. The mass attenuation coefficient values measured from experiment and are compared with theoretical methods using XCOM program. The plots of density versus linear attenuation coefficient for different wood materials correspond to higher order polynomial are presented. It is observed that variation of linear attenuation coefficient depends on densities of materials. The Chloroxylon swietenia with more density has more linear attenuation coefficient at 59.5 KeV and 662 KeV. The variation in attenuation coefficient attributed to chemical composition of wood used in the experiment.

  19. [A study on image processing of digital radiography and measure of material micro-density directly].

    Science.gov (United States)

    Xia, Ping; Xu, Guang-Ming; Yin, Song; Liu, Sheng-Quan; Xu, Lian-Yuan

    2008-05-01

    Due to the high influents of the device itself and the surrounding environment, the background brightness of the digital radiography image is uniform and the image shows big noise. Therefore, in order to identify digital radiography images precisely, a further image processing is necessary. In this study, adaptive filtering, histogram equalization techniques and difference image methods were used for image processing and the results show that these techniques were useful to denoise, to intensify brightness and to rectify the background. In order to verify the feasibility of these techniques, poplar wood samples of heterogeneous material were used as experimental materials and Micro-density was measured directly by applying the linear relationship between grey scale of DR image and penetrate material density and contrasted with the result of microdensitometer. The results show these techniques were feasible and even gave a more precise measurement on wood micro-density compared to microdensitometer.

  20. van der Waals Density Functional Theory vdW-DFq for Semihard Materials

    Science.gov (United States)

    Peng, Qing; de, Suvranu

    There are a large number of materials with mild stiffness, which are not as soft as tissues and not as strong as metals. These semihard materials includes energetic materials, molecular crystals, layered materials, and van der Waals crystals. The integrity and mechanical stability are mainly determined by the interactions between instantaneously induced dipoles, the so called London dispersion force or van der Waals force. It is challenging to accurately model the structural and mechanical properties of these semihard materials in the frame of density functional theory where the non-local correlation functionals are not well known. Here we propose a van der Waals density functional named vdW-DFq to accurately model the density and geometry of semihard materials. Using β-cyclotetramethylene tetranitramine as a prototype, we adjust the enhancement factor of the exchange energy functional with generalized gradient approximations. We find this method to be simple and robust over a wide tuning range when calibrating the functional on-demand with experimental data. With a calibrated value q = 1 . 05 , the proposed vdW-DFq method shows good performance in predicting the geometries of 11 common energetic material molecular crystals and 3 typical layered van der Waals crystals. The authors would like to acknowledge the generous financial support from the Defense Threat Reduction Agency (DTRA) Grant # HDTRA1-13-1-0025.

  1. Characteristic parameters of diffusive supersonic radiation transport in low density materials

    Institute of Scientific and Technical Information of China (English)

    Jiang Shao-En; Yang Jia-Min; Zheng Zhi-Jian; Ding Yong-Kun

    2007-01-01

    Diffusive heat waves play an important role in radiation hydrodynamics. In low density material, it may be possible that the radiative energy flux dominates the material energy flux and thus energy flow can be determined. In this paper by means of a simple algebraic method, the expressions characterizing the condition of diffusion approximation and supersonic transport of heat wave are found. In this case, the ratio of the radiative energy flux to the material energy flux is directly proportional to the product of Mach number M multiplied by optical depth τ. And it may also be expressed by radiation temperature heating material. The materiel density and length may be determined in order to aceve above-mentioned conditions when the driven temperature and duration are given.

  2. Density functional theory and beyond-opportunities for quantum methods in materials modeling semiconductor technology.

    Science.gov (United States)

    Shankar, Sadasivan; Simka, Harsono; Haverty, Michael

    2008-02-13

    In the semiconductor industry, the use of new materials has been increasing with the advent of nanotechnology. As critical dimensions decrease, and the number of materials increases, the interactions between heterogeneous materials themselves and processing increase in complexity. Traditionally, applications of ab initio techniques are confined to electronic structure and band gap calculations of bulk materials, which are then used in coarse-grained models such as mesoscopic and continuum models. Density functional theory is the most widely used ab initio technique that was successfully extended to several applications. This paper illustrates applications of density functional theory to semiconductor processes and proposes further opportunities for use of such techniques in process development.

  3. Density of loose-fill insulation material exposed to cyclic humidity conditions

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    the granulated loose-fill material is exposed to a climate that is characterised as cyclic humidity conditions (a constant temperature and a relative humidity alternating between two predetermined constant relative humidity levels). A better understanding of the behaviour of granulated loose-fill material...... is provided and a standardised method is proposed. This enables control of the settling and prediction of densities necessary to prevent settling. The Nordtest, Organisation for Testing in Scandinavia funded the Nordtest Projekt 1623-03....

  4. Ru/Al Multilayers Integrate Maximum Energy Density and Ductility for Reactive Materials

    OpenAIRE

    K. Woll; Bergamaschi, A; Avchachov, K.; Djurabekova, F.; Gier, S.; Pauly, C.; Leibenguth, P.; Wagner, C; Nordlund, K.; Mücklich, F

    2016-01-01

    Established and already commercialized energetic materials, such as those based on Ni/Al for joining, lack the adequate combination of high energy density and ductile reaction products. To join components, this combination is required for mechanically reliable bonds. In addition to the improvement of existing technologies, expansion into new fields of application can also be anticipated which triggers the search for improved materials. Here, we present a comprehensive characterization of the ...

  5. Range shift and dose perturbation with high-density materials in proton beam therapy

    Energy Technology Data Exchange (ETDEWEB)

    Nichiporov, D., E-mail: nichipor@indiana.edu [Indiana University Integrated Science and Technology Hall, 2401 Milo B. Sampson La, Bloomington, IN 47408-1398 (United States); Moskvin, V. [Indiana University School of Medicine, 535 Barnhill Dr., RT 041, Indianapolis, IN 46202 (United States); Indiana University Health Proton Therapy Center, 2425 Milo B. Sampson La, Bloomington, IN 47408 (United States); Fanelli, L. [Indiana University Health Proton Therapy Center, 2425 Milo B. Sampson La, Bloomington, IN 47408 (United States); Das, I.J. [Indiana University School of Medicine, 535 Barnhill Dr., RT 041, Indianapolis, IN 46202 (United States); Indiana University Health Proton Therapy Center, 2425 Milo B. Sampson La, Bloomington, IN 47408 (United States)

    2011-11-15

    Radiotherapy with proton beams requires accurate knowledge of the proton range. When materials with high atomic numbers (Z) and densities (e.g. prostheses or implants) are present in the patient, they give rise to pronounced uncertainties in computed tomography data and to large errors in proton range and dose calculations. A modified analytical expression is proposed for the observed range shift in water in the presence of a high-density material of known thickness and density. The expression was verified experimentally in a clinical beam with various thicknesses and materials in a water phantom, at several beam ranges and at different depths. Measurements were also made behind the medium-to-water interface to evaluate dose perturbation using a thin window parallel plate ion chamber. Primary particle fluence variations due to the range shift were studied in a separate experiment. The measured range shift was in good agreement ({+-}0.3 mm) with the analytical expression for most of the materials studied. A small, but consistent dependence of range shift on the energy of impinging protons was found. Dose perturbation factor in water downstream of the material is less than +5% for thicknesses up to 8 g/cm{sup 2}. The proposed analytical expression can be used in clinical situations to determine the range shift in patient caused by an implanted material. Dose perturbation in the presence of an implant is due to the changes in primary particle fluence resulting from several physical processes.

  6. Density functional studies of functionalized graphitic materials with late transition metals for oxygen reduction reactions

    DEFF Research Database (Denmark)

    Vallejo, Federico Calle; Martinez, Jose Ignacio; Rossmeisl, Jan

    2011-01-01

    ) at the cathode. In this contribution, on the basis of Density Functional Theory (DFT) calculations, we show that graphitic materials with active sites composed of 4 nitrogen atoms and transition metal atoms belonging to groups 7 to 9 in the periodic table are active towards ORR, and also towards Oxygen Evolution...

  7. Some considerations of organic materials for high density optical disk data storage

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The application possibilities of organic materials for high density optical disk data storage are discussed.Several points,such as physical and chemical stabilities,wavelength match and reversible property changes,which should be taken into consideration,are presented.

  8. Measuring the Density of Different Materials by Using the Collimated Fast Neutron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Sudac, D.; Nad, K.; Orlic, Z.; Obhodas, J. [Rudjer Boskovic Institute, Bijenicka c. 54, 10000 Zagreb (Croatia); Valkovic, V. [Rudjer Boskovic Institute, Zagreb (Croatia); Kvinticka 62, Zagreb (Croatia)

    2015-07-01

    It was demonstrated in the previous work that various threat materials could be detected inside the sea going cargo container by measuring the three variables, carbon and oxygen concentration and density of investigated material. Density was determined by measuring transmitted neutrons, which is not always practical in terms of setting up the instrument geometry. In order to enable more geometry flexibility, we have investigated the possibility of using the scattered neutrons in cargo material identification. For that purpose, the densities of different materials were measured depending on the position of neutron detectors and neutron generator with respect to the target position. One neutron detector was put above the target, one behind and one in front of the target, above the neutron generator. It was shown that all three positions of neutron detectors can be successfully used to measure the target density, but only if the detected neutrons are successfully discriminated from the gamma rays. Although the associated alpha particle technique/associate particle imaging (API) was used to discriminate the neutrons from the gamma rays, it is believed that the same results would be obtained by using the pulse shape discrimination method. In that way API technique can be avoided and the neutron generator which produces much higher beam intensity than 10{sup 8} n/s can be used. (authors)

  9. Metal azides under pressure: An emerging class of high energy density materials

    Indian Academy of Sciences (India)

    G Vaitheeswaran; K Ramesh Babu

    2012-11-01

    Metal azides are well-known for their explosive properties such as detonation or deflagration. As chemically pure sources of nitrogen, alkali metal azides under high pressure have the ability to form polymeric nitrogen, an ultimate green high energy density material with energy density three times greater than that of known high energetic materials. With this motive, in this present work, we try to address the high-pressure behaviour of LiN3 and KN3 by means of density functional calculations. All the calculations are performed with the inclusion of van derWaals interactions at semi empirical level, as these materials are typical molecular solids. We found that both LiN3 and KN3 are structurally stable up to the studied pressure range of 60 GPa and 16 GPa, respectively. At ambient conditions both the materials are insulators with a gap of 3.48 eV (LiN3) and 4.08 eV (KN3) and as pressure increases the band gap decreases and show semiconducting nature at high pressures.We also found that the compressibility of both the crystals is anisotropic which is in good agreement with experiment. Our theoretical study proved that the materials under study may have the ability to form polymeric nitrogen because of the decrease in interazide ion distance and possible overlapping of N atomic orbitals.

  10. α MnMoO₄/graphene hybrid composite: high energy density supercapacitor electrode material.

    Science.gov (United States)

    Ghosh, Debasis; Giri, Soumen; Moniruzzaman, Md; Basu, Tanya; Mandal, Manas; Das, Chapal Kumar

    2014-07-28

    A unique and cost effective hydrothermal procedure has been carried out for the synthesis of hexahedron shaped α MnMoO4 and its hybrid composite with graphene using three different weight percentages of graphene. Characterization techniques, such as XRD, Raman and FTIR analysis, established the phase and formation of the composite. The electrochemical characterization of the pseudocapacitive MnMoO4 and the MnMoO4/graphene composites in 1 M Na2SO4 displayed highest specific capacitances of 234 F g(-1) and 364 F g(-1), respectively at a current density of 2 A g(-1). Unlike many other pseudocapacitive electrode materials our prepared materials responded in a wide range of working potentials of (-)1 V to (+)1 V, which indeed resulted in a high energy density without substantial loss of power density. The highest energy densities of 130 Wh kg(-1) and 202.2 Wh kg(-1) were achieved, respectively for the MnMoO4 and the MnMoO4/graphene composite at a constant power delivery rate of 2000 W kg(-1). The synergistic effect of the graphene with the pseudocapacitive MnMoO4 caused an increased cycle stability of 88% specific capacitance retention after 1000 consecutive charge discharge cycles at 8 A g(-1) constant current density, which was higher than the virgin MnMoO4 with 84% specific capacitance retention.

  11. Progress in High Power Density SOFC Material Development for Aerospace Applications

    Science.gov (United States)

    Cable, Thomas L.; Sofie, Stephen W.; Setlock, John A.; Misra, Ajay K.

    2004-01-01

    Solid oxide fuel cell (SOFC) systems for aircraft applications require order of magnitude increase in specific power density and long life under aircraft operating conditions. Advanced SOFC materials and fabrication processes are being developed at NASA GRC to increase specific power density and durability of SOFC cell and stack. Initial research efforts for increasing specific power density are directed toward increasing the operating temperature for the SOFC system and reducing the weight of the stack. While significant research is underway to develop anode supported SOFC system operating at temperatures in the range of 650 - 850 C for ground power generation applications, such temperatures may not yield the power densities required for aircraft applications. For electrode-supported cells, SOFC stacks with power densities greater than 1.0 W/sq cm are favorable at temperatures in excess of 900 C. The performance of various commercial and developmental anode supported cells is currently being evaluated in the temperature range of 900 to 1000 C to assess the performance gains and materials reliability. The results from these studies will be presented. Since metal interconnects developed for lower temperature operation are not practical at these high temperatures, advanced perovskite based ceramic interconnects with high electronic conductivity and lower sintering temperatures are being developed. Another option for increasing specific power density of SOFC stacks is to decrease the stack weight. Since the interconnect contributes to a significant portion of the stack weight, considerable weight benefits can be derived by decreasing its thickness. Eliminating the gas channels in the interconnect by engineering the pore structure in both anode and cathode can offer significant reduction in thickness of the ceramic interconnect material. New solid oxide fuel cells are being developed with porous engineered electrode supported structures with a 10 - 20 micron thin

  12. Expancel Foams: Fabrication and Characterization of a New Reduced Density Cellular Material for Structural Applications

    Energy Technology Data Exchange (ETDEWEB)

    L. Whinnery; S. Goods; B. Even

    2000-08-01

    This study was initiated to produce a low-density centering medium for use in experiments investigating the response of materials to shock-loading. While the main drivers for material selection were homogeneity, dimensional stability, performance and cost, other secondary requirements included fine cell size, the ability to manufacture 5--10 cm-sized parts and an extremely compressed development time. The authors chose a non-traditional methodology using a hollow, expandable, polymeric microballoon material system called Expancel{reg_sign}. These microballoons are made from a copolymer of polyacrylonitrile (PAN) and polymethacrylonitrile (PMAN) and use iso-pentane as the blowing agent. The average diameter (by volume) of the unexpanded powder is approximately 13 {micro}m, while the average of the expanded powder is 35--55 {micro}m, with a few large microballoons approaching 150--200 p.m. A processing method was developed that established a pre-mixed combination of unexpanded and expanded Expancel at a ratio such that the tap (or vibration) density of the mixed powders was the same as that desired of the final part. Upon heating above the tack temperature of the polymer, this zero-rise approach allowed only expansion of the unexpanded powder to fill the interstices between the pre-expanded balloons. The mechanical action of the expanding powder combined with the elevated processing temperature yielded flee-standing and mechanically robust parts. Although mechanical properties of these foams were not a key performance requirement, the data allowed for the determination of the best temperature to heat the samples. Processing the foam at higher temperatures enhanced both modulus and strength. The maximum allowable temperature was limited by dimensional stability and shrinkback considerations. Tomographic analysis of foam billets revealed very flat density profiles. Parts of any density between the low density expanded powder (approximately 0.013 g/cm{sup 3}) and the

  13. Isotope-specific detection of low density materials with mono-energetic (gamma)-rays

    Energy Technology Data Exchange (ETDEWEB)

    Albert, F; Anderson, S G; Gibson, D J; Hagmann, C A; Johnson, M S; Messerly, M J; Semenov, V A; Shverdin, M Y; Tremaine, A M; Hartemann, F V; Siders, C W; McNabb, D P; Barty, C J

    2009-03-16

    The first demonstration of isotope-specific detection of a low-Z, low density object, shielded by a high-Z and high density material using mono-energetic gamma-rays is reported. Isotope-specific detection of LiH shielded by Pb and Al is accomplished using the nuclear resonance fluorescence line of {sup 7}Li at 0.478 MeV. Resonant photons are produced via laser-based Compton scattering. The detection techniques are general and the confidence level obtained is shown to be superior to that yielded by conventional x-ray/{gamma}-ray techniques in these situations.

  14. Ru/Al Multilayers Integrate Maximum Energy Density and Ductility for Reactive Materials.

    Science.gov (United States)

    Woll, K; Bergamaschi, A; Avchachov, K; Djurabekova, F; Gier, S; Pauly, C; Leibenguth, P; Wagner, C; Nordlund, K; Mücklich, F

    2016-01-01

    Established and already commercialized energetic materials, such as those based on Ni/Al for joining, lack the adequate combination of high energy density and ductile reaction products. To join components, this combination is required for mechanically reliable bonds. In addition to the improvement of existing technologies, expansion into new fields of application can also be anticipated which triggers the search for improved materials. Here, we present a comprehensive characterization of the key parameters that enables us to classify the Ru/Al system as new reactive material among other energetic systems. We finally found that Ru/Al exhibits the unusual integration of high energy density and ductility. For example, we measured reaction front velocities up to 10.9 (± 0.33) ms(-1) and peak reaction temperatures of about 2000 °C indicating the elevated energy density. To our knowledge, such high temperatures have never been reported in experiments for metallic multilayers. In situ experiments show the synthesis of a single-phase B2-RuAl microstructure ensuring improved ductility. Molecular dynamics simulations corroborate the transformation behavior to RuAl. This study fundamentally characterizes a Ru/Al system and demonstrates its enhanced properties fulfilling the identification requirements of a novel nanoscaled energetic material.

  15. Dislocation-density based description of the deformation of a composite material

    Science.gov (United States)

    Schulz, K.; Sudmanns, M.; Gumbsch, P.

    2017-09-01

    Composite materials consisting of hard particles in a ductile metallic matrix are of major interest since their strength and deformability can be dramatically changed by varying volume fraction, size and shape of the particles. Understanding dislocation motion in composite materials as the cause of plastic deformation therefore is an important task. Recently, advanced dislocation-based continuum theories of plasticity have been developed for performing meaningful averages over systems of straight and curved dislocation lines in a continuum approach. In this paper, we focus on a single slip heterogeneous microstructure and investigate how the dislocation interactions can be represented in an averaged dislocation density based continuum description. The representation of strong dislocation density gradients is discussed in the context of a formulation, which aims at a coarse-grained resolution. We introduce a set of dislocation density evolution equations which account for the formation and dissolution of dislocation dipoles. By applying the model to a composite structure, we demonstrate that the dislocation density based description can well describe the physical processes in the microstructure and a comparison to discrete dislocation dynamics simulations shows good agreement for the relaxation behavior of the considered composites.

  16. Graphene, a material for high temperature devices; intrinsic carrier density, carrier drift velocity, and lattice energy

    CERN Document Server

    Yin, Yan; Wang, Li; Jin, Kuijuan; Wang, Wenzhong

    2016-01-01

    Heat has always been a killing matter for traditional semiconductor machines. The underlining physical reason is that the intrinsic carrier density of a device made from a traditional semiconductor material increases very fast with a rising temperature. Once reaching a temperature, the density surpasses the chemical doping or gating effect, any p-n junction or transistor made from the semiconductor will fail to function. Here, we measure the intrinsic Fermi level (|E_F|=2.93k_B*T) or intrinsic carrier density (n_in=3.87*10^6 cm^-2 K^-2*T^2), carrier drift velocity, and G mode phonon energy of graphene devices and their temperature dependencies up to 2400 K. Our results show intrinsic carrier density of graphene is an order of magnitude less sensitive to temperature than those of Si or Ge, and reveal the great potentials of graphene as a material for high temperature devices. We also observe a linear decline of saturation drift velocity with increasing temperature, and identify the temperature coefficients of ...

  17. Energetic multifunctionalized nitraminopyrazoles and their ionic derivatives: ternary hydrogen-bond induced high energy density materials.

    Science.gov (United States)

    Yin, Ping; Parrish, Damon A; Shreeve, Jean'ne M

    2015-04-15

    Diverse functionalization was introduced into the pyrazole framework giving rise to a new family of ternary hydrogen-bond induced high energy density materials. By incorporating extended cationic interactions, nitramine-based ionic derivatives exhibit good energetic performance and enhanced molecular stability. Performance parameters including heats of formation and detonation properties were calculated by using Gaussian 03 and EXPLO5 v6.01 programs, respectively. It is noteworthy to find that 5-nitramino-3,4-dinitropyrazole, 4, has a remarkable measured density of 1.97 g cm(-3) at 298 K, which is consistent with its crystal density (2.032 g cm(-3), 150 K), and ranks highest among azole-based CHNO compounds. Energetic evaluation indicates that, in addition to the molecular compound 4, some ionic derivatives, 9, 11, 12, 17, 19, and 22, also have high densities (1.83-1.97 g cm(-3)), excellent detonation pressures and velocities (P, 35.6-41.6 GPa; vD, 8880-9430 m s(-1)), as well as acceptable impact and friction sensitivities (IS, 4-30 J; FS, 40-240 N). These attractive features highlight the application potential of nitramino hydrogen-bonded interactions in the design of advanced energetic materials.

  18. The contact density to characterize the mechanics of cohesive granular materials: application to snow microstructure modeling.

    Science.gov (United States)

    Gaume, Johan; Löwe, Henning

    2016-04-01

    Microstructural properties are essential to characterize the mechanics of loose and cohesive granular materials such as snow. In particular, mechanical properties and physical processes of porous media are often related to the volume fraction ν. Low-density microstructures typically allow for considerable structural diversity at a given volume fraction, leading to uncertainties in modeling approaches using ν-based parametrizations only. We have conducted discrete element simulations of cohesive granular materials with initial configurations which are drawn from Baxter's sticky hard sphere (SHS) model. This method allows to control independently the initial volume fraction ν and the average coordination number Z. We show that variations in elasticity and strength of the samples can be fully explained by the initial contact density C = νZ over a wide range of volume fractions and coordination numbers. Hence, accounting for the contact density C allows to resolve the discrepancies in particle based modeling between samples with similar volume fractions but different microstructures. As an application, we applied our method to the microstructure of real snow samples which have been imaged by micro-computed tomography and reconstructed using the SHS model. Our new approach opens a promising route to evaluate snow physical and mechanical properties from field measurements, for instance using the Snow Micro Penetrometer (SMP), by linking the penetration resistance to the contact density.

  19. Advanced High Energy Density Secondary Batteries with Multi-Electron Reaction Materials.

    Science.gov (United States)

    Chen, Renjie; Luo, Rui; Huang, Yongxin; Wu, Feng; Li, Li

    2016-10-01

    Secondary batteries have become important for smart grid and electric vehicle applications, and massive effort has been dedicated to optimizing the current generation and improving their energy density. Multi-electron chemistry has paved a new path for the breaking of the barriers that exist in traditional battery research and applications, and provided new ideas for developing new battery systems that meet energy density requirements. An in-depth understanding of multi-electron chemistries in terms of the charge transfer mechanisms occuring during their electrochemical processes is necessary and urgent for the modification of secondary battery materials and development of secondary battery systems. In this Review, multi-electron chemistry for high energy density electrode materials and the corresponding secondary battery systems are discussed. Specifically, four battery systems based on multi-electron reactions are classified in this review: lithium- and sodium-ion batteries based on monovalent cations; rechargeable batteries based on the insertion of polyvalent cations beyond those of alkali metals; metal-air batteries, and Li-S batteries. It is noted that challenges still exist in the development of multi-electron chemistries that must be overcome to meet the energy density requirements of different battery systems, and much effort has more effort to be devoted to this.

  20. High density porous polyethylene material (Medpor) as an unwrapped orbital implant

    Institute of Scientific and Technical Information of China (English)

    CHEN Yan-hong; CUI Hong-guang

    2006-01-01

    Objective: To introduce the clinical effect among patients who received an unwrapped orbital implant with high density porous polyethylene material (Medpor) after enucleation or evisceration. Methods: Retrospective analysis of a series of 302 patients with anophthalmia who underwent placement of an unwrapped high density porous polyethylene orbital implant. We compared the patients (n=180) who accepted primary implant placement with those (n=122) who accepted secondary implant placement. Parameters evaluated included: age at time of surgery, date of surgery, sex, implant type and size, surgery type, the surgical procedure and technique performed, and complications. Results: The time of follow-up ranged from 2.0 to 58.0 months (mean 32.5 months). A total of 5 of 302 (1.66%) cases had documented postoperative complications. The following problems were noted after surgery: implant exposure, 3 patients (0.99%); implant removed due to orbital infection, 1 patient (0.34%); ptosis, 1 patient (0.34%). There were no significant complications observed in other 297 cases and all implants showed good orbital motility. The clinical effect of primary implant placement is better than that of secondary placement. Conclusion: High density porous polyethylene material can be used successfully as an unwrapped orbital implant in anopthalmic socket surgery with minimal complications. The material is well tolerated, nonantigenic and has low rate of infection and migration.

  1. Novel LLM series high density energy materials: Synthesis, characterization, and thermal stability

    Science.gov (United States)

    Pagoria, Philip; Zhang, Maoxi; Tsyshevskiy, Roman; Kuklja, Maija

    Novel high density energy materials must satisfy specific requirements, such as an increased performance, reliably high stability to external stimuli, cost-efficiency and ease of synthesis, be environmentally benign, and be safe for handling and transportation. During the last decade, the attention of researchers has drifted from widely used nitroester-, nitramine-, and nitroaromatic-based explosives to nitrogen-rich heterocyclic compounds. Good thermal stability, the low melting point, high density, and moderate sensitivity make heterocycle materials attractive candidates for use as oxidizers in rocket propellants and fuels, secondary explosives, and possibly as melt-castable ingredients of high explosive formulations. In this report, the synthesis, characterization, and results of quantum-chemical DFT study of thermal stability of LLM-191, LLM-192 and LLM-200 high density energy materials are presented. Work performed under the auspices of the DOE by the LLNL (Contract DE-AC52-07NA27344). This research is supported in part by ONR (Grant N00014-12-1-0529) and NSF. We used NSF XSEDE (Grant DMR-130077) and DOE NERSC (Contract DE-AC02-05CH11231) resources.

  2. Tailoring correlations of the local density of states in disordered photonic materials

    CERN Document Server

    Riboli, F; Monaco, G; Caselli, N; Intonti, F; Gurioli, M; Skipetrov, S E

    2016-01-01

    We present experimental evidence for the different mechanisms driving the fluctuations of the local density of states (LDOS) in disordered photonic systems. We establish a clear link between the microscopic structure of the material and the frequency correlation function of LDOS accessed by a near-field hyperspectral imaging technique. We show, in particular, that short- and long-range frequency correlations of LDOS are controlled by different physical processes (multiple or single scattering processes, respectively) that can be---to some extent---manipulated independently. We also demonstrate that the single scattering contribution to the LDOS fluctuations is sensitive to subwavelength features of the material and, in particular, to the correlation length of its dielectric function. Our work paves the way towards a complete control of statistical properties of disordered photonic systems, allowing for designing materials with predefined LDOS correlations.

  3. Critical parameters governing energy density of Li-storage cathode materials unraveled by confirmatory factor analysis

    Science.gov (United States)

    Sohn, Kee-Sun; Han, Su Cheol; Park, Woon Bae; Pyo, Myoungho

    2016-03-01

    Despite extensive effort during the past few decades, a comprehensive understanding of the key variables governing the electrochemical properties of cathode materials in Li-ion batteries is still far from complete. To elucidate the critical parameters affecting energy density (ED) and capacity (Q) retention in layer and spinel cathodes, we data-mine the existing experimental data via confirmatory factor analysis (CFA) based on a structural equation model (SEM), which is a proven, versatile tool in understanding complex problems in the social science. The data sets are composed of 18 and 15 parameters extracted from 38 layer and 33 spinel compounds, respectively. CFA reveals the irrelevance of Q retention to all the parameters we adopt, but it also reveals the sensitive variations of ED with specific parameters. We validate the usefulness of CFA in material science and pinpointed critical parameters for high-ED cathodes, hoping to suggest a new insight in materials design.

  4. Scalable Sub-micron Patterning of Organic Materials Toward High Density Soft Electronics.

    Science.gov (United States)

    Kim, Jaekyun; Kim, Myung-Gil; Kim, Jaehyun; Jo, Sangho; Kang, Jingu; Jo, Jeong-Wan; Lee, Woobin; Hwang, Chahwan; Moon, Juhyuk; Yang, Lin; Kim, Yun-Hi; Noh, Yong-Young; Jaung, Jae Yun; Kim, Yong-Hoon; Park, Sung Kyu

    2015-09-28

    The success of silicon based high density integrated circuits ignited explosive expansion of microelectronics. Although the inorganic semiconductors have shown superior carrier mobilities for conventional high speed switching devices, the emergence of unconventional applications, such as flexible electronics, highly sensitive photosensors, large area sensor array, and tailored optoelectronics, brought intensive research on next generation electronic materials. The rationally designed multifunctional soft electronic materials, organic and carbon-based semiconductors, are demonstrated with low-cost solution process, exceptional mechanical stability, and on-demand optoelectronic properties. Unfortunately, the industrial implementation of the soft electronic materials has been hindered due to lack of scalable fine-patterning methods. In this report, we demonstrated facile general route for high throughput sub-micron patterning of soft materials, using spatially selective deep-ultraviolet irradiation. For organic and carbon-based materials, the highly energetic photons (e.g. deep-ultraviolet rays) enable direct photo-conversion from conducting/semiconducting to insulating state through molecular dissociation and disordering with spatial resolution down to a sub-μm-scale. The successful demonstration of organic semiconductor circuitry promise our result proliferate industrial adoption of soft materials for next generation electronics.

  5. Ab initio density-functional calculations in materials science: from quasicrystals over microporous catalysts to spintronics.

    Science.gov (United States)

    Hafner, Jürgen

    2010-09-29

    During the last 20 years computer simulations based on a quantum-mechanical description of the interactions between electrons and atomic nuclei have developed an increasingly important impact on materials science, not only in promoting a deeper understanding of the fundamental physical phenomena, but also enabling the computer-assisted design of materials for future technologies. The backbone of atomic-scale computational materials science is density-functional theory (DFT) which allows us to cast the intractable complexity of electron-electron interactions into the form of an effective single-particle equation determined by the exchange-correlation functional. Progress in DFT-based calculations of the properties of materials and of simulations of processes in materials depends on: (1) the development of improved exchange-correlation functionals and advanced post-DFT methods and their implementation in highly efficient computer codes, (2) the development of methods allowing us to bridge the gaps in the temperature, pressure, time and length scales between the ab initio calculations and real-world experiments and (3) the extension of the functionality of these codes, permitting us to treat additional properties and new processes. In this paper we discuss the current status of techniques for performing quantum-based simulations on materials and present some illustrative examples of applications to complex quasiperiodic alloys, cluster-support interactions in microporous acid catalysts and magnetic nanostructures.

  6. Anomalous Lithium Adsorption Propensity of Monolayer Carbonaceous Materials: A Density Functional Study

    Indian Academy of Sciences (India)

    SWATI PANIGRAHI; DEIVASIGAMANI UMADEVI; G NARAHARI SASTRY

    2016-10-01

    Interaction between lithium and carbonaceous materials has gained a lot of importance in lithium battery industry as an important source of energy and storage. The size, dimension, curvature and chirality of the carbonaceous materials are found to be very important factors in controlling the sequential binding oflithium. The propensity of lithium binding to the monolayer carbonaceous materials has been studied using Density functional theory (DFT). Structural and energetical parameters of the complexes have been analyzed through interaction energy, sequential energy, Mulliken population analysis and spin density distribution. Spindensity of odd Li doped systems reveals the preferences for addition of further lithium atoms on the surface. Upon analyzing the interaction energy in armchair carbon nanotubes (A-CNTs) and zigzag carbon nanotubes (Z-CNTs), it has been observed that external and internal surfaces of CNTs have contrasting binding preferences for sequential addition of Li atoms. Internal surface is found to be more feasible site for lithium adsorption than the external surface. This current study provides fundamental understanding of the mechanism of lithium adsorption in lithium battery.

  7. Nanoscale Tunable Strong Carrier Density Modulation of 2D Materials for Metamaterials and Other Tunable Optoelectronics

    Science.gov (United States)

    Peng, Cheng; Efetov, Dmitri; Shiue, Ren-Jye; Nanot, Sebastien; Hempel, Marek; Kong, Jing; Koppens, Frank; Englund, Dirk

    Strong spatial tunability of the charge carrier density at nanoscale is essential to many 2D-material-based electronic and optoelectronic applications. As an example, plasmonic metamaterials with nanoscale dimensions would make graphene plasmonics at visible and near-infrared wavelengths possible. However, existing gating techniques based on conventional dielectric gating geometries limit the spatial resolution and achievable carrier concentration, strongly restricting the available wavelength, geometry, and quality of the devices. Here, we present a novel spatially selective electrolyte gating approach that allows for in-plane spatial Fermi energy modulation of 2D materials of more than 1 eV (carrier density of n = 1014 cm-2) across a length of 2 nm. We present electrostatic simulations as well as electronic transport, photocurrent, cyclic voltammetry and optical spectroscopy measurements to characterize the performance of the gating technique applied to graphene devices. The high spatial resolution, high doping capacity, full tunability and self-aligned device geometry of the presented technique opens a new venue for nanoscale metamaterial engineering of 2D materials for complete optical absorption, nonlinear optics and sensing, among other applications.

  8. Characterization of Thin Film Materials using SCAN meta-GGA, an Accurate Nonempirical Density Functional

    Science.gov (United States)

    Buda, I. G.; Lane, C.; Barbiellini, B.; Ruzsinszky, A.; Sun, J.; Bansil, A.

    2017-03-01

    We discuss self-consistently obtained ground-state electronic properties of monolayers of graphene and a number of ’beyond graphene’ compounds, including films of transition-metal dichalcogenides (TMDs), using the recently proposed strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (meta-GGA) to the density functional theory. The SCAN meta-GGA results are compared with those based on the local density approximation (LDA) as well as the generalized gradient approximation (GGA). As expected, the GGA yields expanded lattices and softened bonds in relation to the LDA, but the SCAN meta-GGA systematically improves the agreement with experiment. Our study suggests the efficacy of the SCAN functional for accurate modeling of electronic structures of layered materials in high-throughput calculations more generally.

  9. High-Tc superconductor/linear low density polyethylene (LLDPE) composite materials for diamagnetic applications

    Science.gov (United States)

    Bhadrakumari, S.; Predeep, P.

    2006-08-01

    A series of composite samples of YBa2Cu3O7-x and linear low density polyethylene (Y-123/LLDPE) with volume percentage ranging from 0 to 75% was prepared. The crystallinity of the composites was studied using x-ray diffraction (XRD) patterns. It is found that the percentage of crystallinity in the composite samples increases with increasing volume of the LLDPE. A four-phase system for the composite materials may be inferred from a combination of XRD and density data. Repulsive force measurements showed that the diamagnetic properties were preserved in the composites and the samples exhibited appreciable magnetic levitation forces and this force increases with increasing volume fraction of the superconductor filler.

  10. Distributed material density and anisotropy for optimized eigenfrequency of 2D continua

    DEFF Research Database (Denmark)

    Pedersen, Pauli; Pedersen, Niels Leergaard

    2015-01-01

    with respect to material density and from this values of the element OC. Each factor of this expression has a physical interpretation. Stated alternatively, the optimization problem of material distribution is converted into a problem of determining a design of uniform OC values. The constitutive matrices...... are described by non-dimensional matrices with unity norms of trace and Frobenius, and thus this part of the optimized design has no influence on the mass distribution. Gradients of eigenfrequency with respect to the components of these non-dimensional constitutive matrices are therefore simplified......, and an additional optimization criterion shows that the optimized redesign of anisotropy are described directly by the element strains. The fact that all components of an optimal constitutive matrix are expressed by the components of a strain state, imply a reduced number of independent components of an optimal...

  11. Development of high power density cathode materials for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ketterer, B.; Vasilchina, H.; Seemann, K.; Ulrich, S.; Besser, H.; Pfleging, W.; Kaiser, T.; Adelhelm, C. [Forschungszentrum Karlsruhe (Germany). IMF I

    2008-10-15

    Cathode material for Li-ion batteries can be synthesised by r.f. magnetron sputtering of LiCoO{sub 2} targets in a pure Ar plasma. This technique is suitable for large-scale implementation in foil coating set-ups. By choosing the process parameters and by employing post heat treatment nanocrystalline, stoichiometrical LiCoO{sub 2} films can be fabricated which exhibit the desired high temperature phase. The determination of the elementary composition is possible by optical emission spectroscopy including plasma stimulation and carrier gas temperature extraction. The proof of crystal structure is carried out by X-ray diffraction and Raman spectroscopy. Heat treatment can be conventionally realised in a furnace or by laser impact. With regard to increasing the power density, the surface of the cathode material can be enhanced six-fold by laser-assisted surface patterning. (orig.)

  12. Quasi-1D van der Waals materials as high current-density local interconnects (Conference Presentation)

    Science.gov (United States)

    Stolyarov, Maxim; Aytan, Ece; Bloodgood, Matthew; Salguero, Tina T.; Balandin, Alexander A.

    2016-09-01

    The continuous downscaling of interconnect dimensions in combination with the introduction of low-k dielectrics has increased the number of heat dissipation, integration and reliability challenges in modern electronics. As a result, there is a strong need for new materials that have high current-carrying capacity for applications as nanoscale interconnects. In this presentation, we show that quasi-one-dimensional (1D) van der Waals metals such as TaSe3 have excellent breakdown current density exceeding that of 5 MA/cm2. This value is above that currently achievable in conventional copper or aluminum wires. The quasi-1D van der Waals materials are characterized by strong bonds along one dimension and weak van der Waals bonds along two other dimensions. The material for this study was grown by the chemical vapor transport (CVT) method. Both mechanical and chemical exfoliation methods were used to fabricate nanowires with lateral dimensions below 100 nm. The dimensions of the quasi-1D nanowires were verified with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The metal (Ti/Au) contacts for the electrical characterization were deposited using electron beam evaporation (EBE). The measurements were conducted on a number of prototype interconnects with multiple electric contacts to ensure reproducibility. The obtained results suggest that quasi-1D van der Waals metals present a feasible alternative to conventional copper interconnects in terms of the current-carrying capacity and the breakdown current-density. This work was supported, in part, by the SRC and DARPA through STARnet Center for Function Accelerated nanoMaterial Engineering (FAME).

  13. Detonation shock dynamics calibration for pBX 9502 with temperature, density, and material lot variations

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Larry G [Los Alamos National Laboratory; Aslam, Tariq D [Los Alamos National Laboratory

    2010-01-01

    We present a methodology for scaling the detonation shock dynamics D{sub n}[{kappa}] calibration function to accommodate variations in the HE starting material. We apply our model to the insensitive TATB-based explosive PBX 9502, for which we have enough front curvature rate stick data to characterize three material attributes: initial temperature T{sub 0}, nominal density {rho}{sub 0}, and manufacturing lot (representing different microstructures). A useful feature of the model is that it returns an absolute estimate for the reaction zone thickness, {delta}. Lacking demonstrated material metrics(s), we express microstructural variation indirectly, in terms of its effect on {delta}. This results in a D{sub n}[{kappa}] function that depends on T{sub 0}, {rho}{sub 0}, and {delta}. After examining the separate effects of each parameter on D{sub n}[{kappa}], we compute an arc geometry as a validation problem. We compare the calculation to a PBX 9502 arc experiment that was pressed from one of the calibrated HE lots. The agreement between the model and experiment is excellent. We compute worst, nominal, and best-performing material parameter combinations to show how much difference accrues throughout the arc.

  14. Effective density of Aquadag and fullerene soot black carbon reference materials used for SP2 calibration

    Directory of Open Access Journals (Sweden)

    M. Gysel

    2011-08-01

    Full Text Available The mass and effective density of black carbon (BC particles generated from aqueous suspensions of Aquadag and fullerene soot was measured and parametrized as a function of their mobility diameter. The measurements were made by two independent research groups by operating a differential mobility analyser (DMA in series with an aerosol particle mass analyser (APM or a Couette centrifugal particle mass analyser (CPMA. Consistent and reproducible results were found in this study for different production lots of Aquadag, indicating that the effective density of these particles is a stable quantity and largely unaffected by differences in aerosol generation procedures and suspension treatments. The effective density of fullerene soot particles from one production lot was also found to be stable and independent of suspension treatments. Some difference to previous literature data was observed for both Aquadag and fullerene soot at larger particle diameters. Knowledge of the exact relationship between mobility diameter and particle mass is of great importance, as DMAs are commonly used to size-select particles from BC reference materials for calibration of single particle soot photometers (SP2, which quantitatively detect the BC mass in single particles.

  15. Effective density of Aquadag and fullerene soot black carbon reference materials used for SP2 calibration

    Directory of Open Access Journals (Sweden)

    M. Gysel

    2011-12-01

    Full Text Available The mass and effective density of black carbon (BC particles generated from aqueous suspensions of Aquadag and fullerene soot was measured and parametrized as a function of their mobility diameter. The measurements were made by two independent research groups by operating a differential mobility analyser (DMA in series with an aerosol particle mass analyser (APM or a Couette centrifugal particle mass analyser (CPMA. Consistent and reproducible results were found in this study for different production lots of Aquadag, indicating that the effective density of these particles is a stable quantity and largely unaffected by differences in aerosol generation procedures and suspension treatments. The effective density of fullerene soot particles from one production lot was also found to be stable and independent of suspension treatments. Some differences to previous literature data were observed for both Aquadag and fullerene soot at larger particle diameters. Knowledge of the exact relationship between mobility diameter and particle mass is of great importance, as DMAs are commonly used to size-select particles from BC reference materials for calibration of single particle soot photometers (SP2, which quantitatively detect the BC mass in single particles.

  16. A Noncontact Measurement Technique for the Density and Thermal Expansion Coefficient of Solid and Liquid Materials

    Science.gov (United States)

    Chung, Sang K.; Thiessen, David B.; Rhim, Won-Kyu

    1996-01-01

    A noncontact measurement technique for the density and the thermal expansion refractory materials in their molten as well as solid phases is presented. This technique is based on the video image processing of a levitated sample. Experiments were performed using the high-temperature electrostatic levitator (HTESL) at the Jet Propulsion Laboratory in which 2-3 mm diameter samples can be levitated, melted, and radiatively cooled in a vacuum. Due to the axisymmetric nature of the molten samples when levitated in the HTESL, a rather simple digital image analysis can be employed to accurately measure the volumetric change as a function of temperature. Density and the thermal expansion coefficient measurements were made on a pure nickel sample to test the accuracy of the technique in the temperature range of 1045-1565 C. The result for the liquid phase density can be expressed by p = 8.848 + (6.730 x 10(exp -4)) x T (degC) g/cu cm within 0.8% accuracy, and the corresponding thermal expansion coefficient can be expressed by Beta=(9.419 x 10(exp -5)) - (7.165 x 10(exp -9) x T (degC)/K within 0.2% accuracy.

  17. AFM-porosimetry: density and pore volume measurements of particulate materials.

    Science.gov (United States)

    Sörensen, Malin H; Valle-Delgado, Juan J; Corkery, Robert W; Rutland, Mark W; Alberius, Peter C

    2008-06-01

    We introduced the novel technique of AFM-porosimetry and applied it to measure the total pore volume of porous particles with a spherical geometry. The methodology is based on using an atomic force microscope as a balance to measure masses of individual particles. Several particles within the same batch were measured, and by plotting particle mass versus particle volume, the bulk density of the sample can be extracted from the slope of the linear fit. The pore volume is then calculated from the densities of the bulk and matrix materials, respectively. In contrast to nitrogen sorption and mercury porosimetry, this method is capable of measuring the total pore volume regardless of pore size distribution and pore connectivity. In this study, three porous samples were investigated by AFM-porosimetry: one ordered mesoporous sample and two disordered foam structures. All samples were based on a matrix of amorphous silica templated by a block copolymer, Pluronic F127, swollen to various degrees with poly(propylene glycol). In addition, the density of silica spheres without a template was measured by two independent techniques: AFM and the Archimedes principle.

  18. Strength and Density of Geopolymer Mortar Cured at Ambient Temperature for Use as Repair Material

    Science.gov (United States)

    Warid Wazien, A. Z.; Bakri Abdullah, Mohd Mustafa Al; Abd. Razak, Rafiza; Mohd Remy Rozainy, M. A. Z.; Faheem Mohd Tahir, Muhammad

    2016-06-01

    Geopolymers produced by synthesizing aluminosilicate source materials with an alkaline activator solution promised an excellent properties akin to the existing construction material. This study focused on the effect of various binder to sand ratio on geopolymer mortar properties. Mix design of geopolymer mortar was produced using NaOH concentration of 12 molars, ratio of fly ash/alkaline activator and ratio Na2SiO3/NaOH of 2.0 and 2.5 respectively. Samples subsequently ware cured at ambient temperature. The properties of geopolymer mortar were analysed in term of compressive strength and density at different period which are on the 3rd and 7th day of curing. Experimental results revealed that the addition of sand slightly increase the compressive strength of geopolymer. The optimum compressive strength obtained was up to 31.39 MPa on the 7th day. The density of geopolymer mortar was in the range between 2.0 g/cm3 to 2.23 g/cm3. Based on this findings, the special properties promoted by geopolymer mortar display high potential to be implemented in the field of concrete patch repair.

  19. In-situ Production of High Density Polyethylene and Other Useful Materials on Mars

    Science.gov (United States)

    Flynn, Michael

    2005-01-01

    This paper describes a revolutionary materials structure and power storage concept based on the in-situ production of abiotic carbon 4 compounds. One of the largest single mass penalties required to support the human exploration of Mars is the surface habitat. This proposal will use physical chemical technologies to produce high density polyethylene (HDPE) inflatable structures and construction materials from Mars atmospheric CO2. The formation of polyethylene from Mars CO2 is based on the use of the Sabatier and modified Fischer Tropsch reactions. The proposed system will fully integrate with existing in-situ propellant production concepts. The technology will also be capable of supplementing human caloric requirements, providing solid and liquid fuels for energy storage, and providing significant reduction in mission risk. The NASA Mars Reference Mission Definition Team estimated that a conventional Mars surface habitat structure would weigh 10 tonnes. It is estimated that this technology could reduce this mass by 80%. This reduction in mass will significantly contribute to the reduction in total mission cost need to make a Mars mission a reality. In addition the potential reduction of risk provided by the ability to produce C4 and potentially higher carbon based materials in-situ on Mars is significant. Food, fuel, and shelter are only three of many requirements that would be impacted by this research.

  20. In-situ Production of High Density Polyethylene and Other Useful Materials on Mars

    Science.gov (United States)

    Flynn, Michael

    2005-01-01

    This paper describes a revolutionary materials structure and power storage concept based on the in-situ production of abiotic carbon 4 compounds. One of the largest single mass penalties required to support the human exploration of Mars is the surface habitat. This proposal will use physical chemical technologies to produce high density polyethylene (HDPE) inflatable structures and construction materials from Mars atmospheric CO2. The formation of polyethylene from Mars CO2 is based on the use of the Sabatier and modified Fischer Tropsch reactions. The proposed system will fully integrate with existing in-situ propellant production concepts. The technology will also be capable of supplementing human caloric requirements, providing solid and liquid fuels for energy storage, and providing significant reduction in mission risk. The NASA Mars Reference Mission Definition Team estimated that a conventional Mars surface habitat structure would weigh 10 tonnes. It is estimated that this technology could reduce this mass by 80%. This reduction in mass will significantly contribute to the reduction in total mission cost need to make a Mars mission a reality. In addition the potential reduction of risk provided by the ability to produce C4 and potentially higher carbon based materials in-situ on Mars is significant. Food, fuel, and shelter are only three of many requirements that would be impacted by this research.

  1. Density measurements as a condition monitoring approach for following the aging of nuclear power plant cable materials

    Science.gov (United States)

    Gillen, K. T.; Celina, M.; Clough, R. L.

    1999-10-01

    Monitoring changes in material density has been suggested as a potentially useful condition monitoring (CM) method for following the aging of cable jacket and insulation materials in nuclear power plants. In this study, we compare density measurements and ultimate tensile elongation results versus aging time for most of the important generic types of commercial nuclear power plant cable materials. Aging conditions, which include thermal-only, as well as combined radiation plus thermal, were chosen such that potentially anomalous effects caused by diffusion-limited oxidation (DLO) are unimportant. The results show that easily measurable density increases occur in most important cable materials. For some materials and environments, the density change occurs at a fairly constant rate throughout the mechanical property lifetime. For cases involving so-called induction-time behavior, density increases are slow to moderate until after the induction time, at which point they begin to increase dramatically. In other instances, density increases rapidly at first, then slows down. The results offer strong evidence that density measurements, which reflect property changes under both radiation and thermal conditions, could represent a very useful CM approach.

  2. Predicting critical temperatures of iron(II) spin crossover materials: density functional theory plus U approach.

    Science.gov (United States)

    Zhang, Yachao

    2014-12-07

    A first-principles study of critical temperatures (T(c)) of spin crossover (SCO) materials requires accurate description of the strongly correlated 3d electrons as well as much computational effort. This task is still a challenge for the widely used local density or generalized gradient approximations (LDA/GGA) and hybrid functionals. One remedy, termed density functional theory plus U (DFT+U) approach, introduces a Hubbard U term to deal with the localized electrons at marginal computational cost, while treats the delocalized electrons with LDA/GGA. Here, we employ the DFT+U approach to investigate the T(c) of a pair of iron(II) SCO molecular crystals (α and β phase), where identical constituent molecules are packed in different ways. We first calculate the adiabatic high spin-low spin energy splitting ΔE(HL) and molecular vibrational frequencies in both spin states, then obtain the temperature dependent enthalpy and entropy changes (ΔH and ΔS), and finally extract T(c) by exploiting the ΔH/T - T and ΔS - T relationships. The results are in agreement with experiment. Analysis of geometries and electronic structures shows that the local ligand field in the α phase is slightly weakened by the H-bondings involving the ligand atoms and the specific crystal packing style. We find that this effect is largely responsible for the difference in T(c) of the two phases. This study shows the applicability of the DFT+U approach for predicting T(c) of SCO materials, and provides a clear insight into the subtle influence of the crystal packing effects on SCO behavior.

  3. Ab-initio simulations of materials using VASP: Density-functional theory and beyond.

    Science.gov (United States)

    Hafner, Jürgen

    2008-10-01

    During the past decade, computer simulations based on a quantum-mechanical description of the interactions between electrons and between electrons and atomic nuclei have developed an increasingly important impact on solid-state physics and chemistry and on materials science-promoting not only a deeper understanding, but also the possibility to contribute significantly to materials design for future technologies. This development is based on two important columns: (i) The improved description of electronic many-body effects within density-functional theory (DFT) and the upcoming post-DFT methods. (ii) The implementation of the new functionals and many-body techniques within highly efficient, stable, and versatile computer codes, which allow to exploit the potential of modern computer architectures. In this review, I discuss the implementation of various DFT functionals [local-density approximation (LDA), generalized gradient approximation (GGA), meta-GGA, hybrid functional mixing DFT, and exact (Hartree-Fock) exchange] and post-DFT approaches [DFT + U for strong electronic correlations in narrow bands, many-body perturbation theory (GW) for quasiparticle spectra, dynamical correlation effects via the adiabatic-connection fluctuation-dissipation theorem (AC-FDT)] in the Vienna ab initio simulation package VASP. VASP is a plane-wave all-electron code using the projector-augmented wave method to describe the electron-core interaction. The code uses fast iterative techniques for the diagonalization of the DFT Hamiltonian and allows to perform total-energy calculations and structural optimizations for systems with thousands of atoms and ab initio molecular dynamics simulations for ensembles with a few hundred atoms extending over several tens of ps. Applications in many different areas (structure and phase stability, mechanical and dynamical properties, liquids, glasses and quasicrystals, magnetism and magnetic nanostructures, semiconductors and insulators, surfaces

  4. Photoelectron spectroscopy and density functional theory studies of N-rich energetic materials.

    Science.gov (United States)

    Zeng, Zhen; Bernstein, Elliot R

    2016-10-28

    The geometric and electronic structures of molecular anionic energetic materials (EMs) DAAF (3,3'-diamino-4,4'-azoxyfurazan), FOX-7 (1,1-diamino-2,2-dinitroethene), 5,5'-BT (5,5'-bistetrazole), and 1,5'-BT (1,5'-bistetrazole) are explored employing anionic photoelectron spectroscopy and density functional theory calculations. The electron binding energies of the observed anionic, energetic material related species are determined and their corresponding anionic structures are assigned. Decomposition reactions for negatively charged EMs can proceed with different energy barriers, and thus mechanisms, from those for their related neutral EMs. Reactivity based on the anionic initial fragments of these EM species further reinforces their respective highly reactive and explosive nature. Fragment ions of the form EM(-)-H-X (X = N2, N2+NH, …) are additionally observed. Detection of such species suggests that EM(-)-H could serve as promising new candidates for EMs, assuming that such species are synthetically available, perhaps as energetic salts. Vertical detachment energies for transitions to the ground and first triplet electronic excited states of neutral matrix dye anion DCM(-) are additionally determined.

  5. Thermo-mechanical characterisation of low density carbon foams and composite materials for the ATLAS upgrade

    CERN Document Server

    Isaac, Bonad

    As a result of the need to increase the luminosity of the Large Hadron Collider (LHC) at CERN-Geneva by 2020, the ATLAS detector requires an upgraded inner tracker. Up- grading the ATLAS experiment is essential due to higher radiation levels and high particle occupancies. The design of this improved inner tracker detector involves development of silicon sensors and their support structures. These support structures need to have well un- derstood thermal properties and be dimensionally stable in order to allow efficient cooling of the silicon and accurate track reconstruction. The work presented in this thesis is an in- vestigation which aims to qualitatively characterise the thermal and mechanical properties of the materials involved in the design of the inner tracker of the ATLAS upgrade. These materials are silicon carbide foam (SiC foam), low density carbon foams such as PocoFoam and Allcomp foam, Thermal Pyrolytic Graphite (TPG), carbon/carbon and Carbon Fibre Re- inforced Polymer (CFRP). The work involve...

  6. Photoelectron spectroscopy and density functional theory studies of N-rich energetic materials

    Science.gov (United States)

    Zeng, Zhen; Bernstein, Elliot R.

    2016-10-01

    The geometric and electronic structures of molecular anionic energetic materials (EMs) DAAF (3,3'-diamino-4,4'-azoxyfurazan), FOX-7 (1,1-diamino-2,2-dinitroethene), 5,5'-BT (5,5'-bistetrazole), and 1,5'-BT (1,5'-bistetrazole) are explored employing anionic photoelectron spectroscopy and density functional theory calculations. The electron binding energies of the observed anionic, energetic material related species are determined and their corresponding anionic structures are assigned. Decomposition reactions for negatively charged EMs can proceed with different energy barriers, and thus mechanisms, from those for their related neutral EMs. Reactivity based on the anionic initial fragments of these EM species further reinforces their respective highly reactive and explosive nature. Fragment ions of the form EM--H-X (X = N2, N2+NH, …) are additionally observed. Detection of such species suggests that EM--H could serve as promising new candidates for EMs, assuming that such species are synthetically available, perhaps as energetic salts. Vertical detachment energies for transitions to the ground and first triplet electronic excited states of neutral matrix dye anion DCM- are additionally determined.

  7. Effect of expanded graphite on the phase change materials of high density polyethylene/wax blends

    Energy Technology Data Exchange (ETDEWEB)

    AlMaadeed, M.A., E-mail: m.alali@qu.edu.qa [Center for Advanced Materials, Qatar University, 2713 Doha (Qatar); Labidi, Sami [Center for Advanced Materials, Qatar University, 2713 Doha (Qatar); Krupa, Igor [QAPCO Polymer Chair, Center for Advanced Materials, Qatar University, P.O. Box 2713, Doha (Qatar); Karkri, Mustapha [Université Paris-Est CERTES, 61 avenue du Général de Gaulle, 94010 Créteil (France)

    2015-01-20

    Highlights: • Expanded graphite (EG) and low melting point (42.3 °C) wax were added to HDPE to form phase change material. • EG was well dispersed in the composites and did not affect the melting or crystallization of the HDPE matrix. • EG increased the thermal stability of the composites by reducing chain mobility and inhibiting degradation. • The addition of a relatively small quantity of EG enhances the heat conduction in the composite. • HDPE/40% RT42 that contained up to 15% EG demonstrated excellent mechanical and thermal properties and can be used as PCM. - Abstract: Phase change materials fabricated from high density polyethylene (HDPE) blended with 40 or 50 wt% commercial wax (melting point of 43.08 °C) and up to 15 wt% expanded graphite (EG) were studied. Techniques including scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and an experimental device to measure diffusivity and conductivity (DICO) were used to determine the microstructural, mechanical and thermal properties of the composites. The composites possessed good mechanical properties. Additionally, no leaching was observed during material processing or characterization. Although the Young’s modulus increased with the addition of EG, no significant changes in tensile strength were detected. The maximum Young’s modulus achieved was 650 MPa for the HDPE/40% wax composite with 15 wt% EG. The EG was well dispersed within the composites and did not affect the melting or crystallization of the HDPE matrix. The incorporation of EG increased the thermal stability of the composites by reducing chain mobility and inhibiting degradation. The intensification of thermal conductivity occurred with increasing fractions of EG, which was attributed to the high thermal conductivity of graphite. The maximum quantity of heat stored by latent heat was found for the HDPE/40% wax composite with EG. The addition of a relatively small quantity

  8. Calculation of polarization and bound charge density inside a dielectric material in triboelectric nanogenerators: Analytical and numerical study

    Science.gov (United States)

    Kim, SeongMin; Ha, Jaewook; Kim, Jin-Baek

    2016-11-01

    We analytically calculated polarization and bound charge density inside the dielectric material in metal-to-dielectric-mode triboelectric nanogenerators (TENG) where the transferred charges are collected on the bottom metal via electrostatic induction from the triboelectric charges that are generated by frictional contact. This bound charge density is associated with the surface density of states (DOS), overline{Ns(E)}. Two cases are considered here: i) for overline{Ns(E)} ≫ 1, it is calculated that the bound charge density is proportional to the dielectric constant and the work function difference between the two materials, but inversely proportional to the thickness of the dielectric material (ɛ0(ɛ2-1) (E0-W)/e \\cdot d2); ii) for overline{Ns(E)} ≪ 1 with constant overline{Ns(E)}, the bound charge density is mostly proportional to the work function difference between the materials, and inversely proportional to the thickness of the dielectric material ((ɛ2-1)x/d_{2+\\varepsilon2\\cdot x} \\cdot Ns(E)\\cdot e\\cdot (E0-W)).

  9. Analysis of Interface Charge Densities for High-k Dielectric Materials based Metal Oxide Semiconductor Devices

    Science.gov (United States)

    Maity, N. P.; Thakur, R. R.; Maity, Reshmi; Thapa, R. K.; Baishya, S.

    2016-10-01

    In this paper, the interface charge densities (Dit) are studied and analyzed for ultra thin dielectric metal oxide semiconductor (MOS) devices using different high-k dielectric materials such as Al2O3, ZrO2 and HfO2. The Dit have been calculated by a new approach using conductance method and it indicates that by reducing the thickness of the oxide, the Dit increases and similar increase is also found by replacing SiO2 with high-k. For the same oxide thickness, SiO2 has the lowest Dit and found to be the order of 1011cm-2eV-1. Linear increase in Dit has been observed as the dielectric constant of the oxide increases. The Dit is found to be in good agreement with published fabrication results at p-type doping level of 1×1017cm-3. Numerical calculations and solutions are performed by MATLAB and device simulation is done by ATLAS.

  10. Density functional theory based tight binding study on theoretical prediction of low-density nanoporous phases ZnO semiconductor materials

    Science.gov (United States)

    Tuoc, Vu Ngoc; Doan Huan, Tran; Viet Minh, Nguyen; Thi Thao, Nguyen

    2016-06-01

    Polymorphs or phases - different inorganic solids structures of the same composition usually have widely differing properties and applications, thereby synthesizing or predicting new classes of polymorphs for a certain compound is of great significance and has been gaining considerable interest. Herein, we perform a density functional theory based tight binding (DFTB) study on theoretical prediction of several new phases series of II-VI semiconductor material ZnO nanoporous phases from their bottom-up building blocks. Among these, three phases are reported for the first time, which could greatly expand the family of II- VI compound nanoporous phases. We also show that all these generally can be categorized similarly to the aluminosilicate zeolites inorganic open-framework materials. The hollow cage structure of the corresponding building block ZnkOk (k= 9, 12, 16) is well preserved in all of them, which leads to their low-density nanoporous and high flexibility. Additionally the electronic wide-energy gap of the individual ZnkOk is also retained. Our study reveals that they are all semiconductor materials with a large band gap. Further, this study is likely to be the common for II-VI semiconductor compounds and will be helpful for extending their range of properties and applications.

  11. Development of a poly(dimethylacrylamide) based matrix material for solid phase high density peptide array synthesis employing a laser based material transfer

    Science.gov (United States)

    Ridder, Barbara; Foertsch, Tobias C.; Welle, Alexander; Mattes, Daniela S.; von Bojnicic-Kninski, Clemens M.; Loeffler, Felix F.; Nesterov-Mueller, Alexander; Meier, Michael A. R.; Breitling, Frank

    2016-12-01

    Poly(dimethylacrylamide) (PDMA) based matrix materials were developed for laser-based in situ solid phase peptide synthesis to produce high density arrays. In this specific array synthesis approach, amino acid derivatives are embedded into a matrix material, serving as a "solid" solvent material at room temperature. Then, a laser pulse transfers this mixture to the target position on a synthesis slide, where the peptide array is synthesized. Upon heating above the glass transition temperature of the matrix material, it softens, allowing diffusion of the amino acid derivatives to the synthesis surface and serving as a solvent for peptide bond formation. Here, we synthesized PDMA six-arm star polymers, offering the desired matrix material properties, using atom transfer radical polymerization. With the synthesized polymers as matrix material, we structured and synthesized arrays with combinatorial laser transfer. With densities of up to 20,000 peptide spots per cm2, the resolution could be increased compared to the commercially available standard matrix material. Time-of-Flight Secondary Ion Mass Spectrometry experiments revealed the penetration behavior of an amino acid derivative into the prepared acceptor synthesis surface and the effectiveness of the washing protocols.

  12. Low-Density and High Porosity Hydrogen Storage Materials Built from Ultra-Light Elements. Final Scientific/Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Pingyun [Univ. of California, Riverside, CA (United States)

    2014-01-10

    A number of significant advances have been achieved, opening up new opportunities for the synthetic development of novel porous materials and their energy-related applications including gas storage and separation and catalysis. These include lithium-based metal-organic frameworks, magnesium-based metal-organic frameworks, and high gas uptake in porous frameworks with high density of open donor sites.

  13. A flexible and high-voltage internal tandem supercapacitor based on graphene-based porous materials with ultrahigh energy density.

    Science.gov (United States)

    Zhang, Fan; Lu, Yanhong; Yang, Xi; Zhang, Long; Zhang, Tengfei; Leng, Kai; Wu, Yingpeng; Huang, Yi; Ma, Yanfeng; Chen, Yongsheng

    2014-06-12

    Pursuing higher working voltage and packaged energy density, an internal tandem supercapacitor has been successfully designed and fabricated based on graphene-based porous carbon hybrid material. Compared with the packaged energy density of 27.2 Wh kgcell (-1) and working voltage of 3.5 V using EMIMBF4 electrolyte for the conventional single-cell supercapacitor, the internal tandem device with the same material achieves a much higher working voltage of 7 V as well as a significantly improved energy density of 36.3 Wh kgcell (-1) (increased by 33%), which is also about 7 times of that of the state-of-art commercial supercapacitors. A flexible internal tandem device is also designed and fabricated and demonstrated similar excellent performance.

  14. Dual-energy X-ray absorptiometry for the simultaneous determination of Density and Moisture Content in Porous Structural Materials

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Jensen, Signe Kamp; Gerward, Leif

    1999-01-01

    The paper describes the dual-energy x-ray equipment, which consists of a x-ray source, filters and a detector. The x-ray beam can be moved automatically in two dimensions relative to a fixed specimen. The purpose of the equipment is to measure simultaneously the density and moisture content......-ray measurements show good agreement with results from the two standard materials which imitate water in a porous material. On this background the dual-energy x-ray absorptiometry measurement principle can be used on porous structural materials....

  15. Determination of total mass attenuation coefficients, effective atomic numbers and electron densities for different shielding materials used in radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    Almeida J, A. T. [FUNDACENTRO, Centro Regional de Minas Gerais, Brazilian Institute for Safety and Health at Work, Belo Horizonte, 30180-100 Minas Gerais (Brazil); Nogueira, M. S. [Center of Development of Nuclear Technology / CNEN, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil); Santos, M. A. P., E-mail: mnogue@cdtn.br [Regional Center for Nuclear Science / CNEN, 50.740-540 Recife, Pernambuco (Brazil)

    2015-10-15

    Full text: In this paper, the interaction of X-rays with some shielding materials has been studied for materials containing different amounts of barite and aggregates. The total mass attenuation coefficient (μ{sub t}) for three shielding materials has been calculated by using WinXCOM program in the energy range from RQR qualities (RQR-4, RQR-6, RQR-9, and RQR-10). They were: cream barite (density 2.99 g/cm{sup 3} collected in the State of Sao Paulo), purple barite (density 2.95 g/cm{sup 3} collected in the State of Bahia) and white barite (density 3.10 g/cm{sup 3} collected in the State of Paraiba). The chemical analysis was carried out by an X-ray fluorescence spectrometer model EDX-720, through dispersive energy. The six elements of the higher concentration found in the sample and analyzed by Spectrophotometry of Energy Dispersive X-ray for the samples were Ba(60.9% - white barite), Ca(17,92% - cream barite), Ce(3,60% - white barite), Fe(17,16% - purple barite), S(12,11% - white barite) and Si(29,61% - purple barite). Also, the effective atomic number (Z{sub eff}) and the effective electron density (N{sub eff}) were calculated using the values of the total mass attenuation coefficient. The dependence of these parameters on the incident photon energy and the chemical composition has been examined. (Author)

  16. Effect of raw material properties and die geometry on the density of biomass pellets from composted municipal solid waste

    Directory of Open Access Journals (Sweden)

    Abedin Zafari

    2012-11-01

    Full Text Available Densification of biomass feedstocks, such as pelletizing, can increase bulk density, improve storability, reduce transportation costs, and ease the handling of biomass using existing handling and storage equipment for grains. In order to study the pelletizing process, compost pellets were produced under controlled conditions. The aim of the work was to investigate the effect of raw material properties and the die geometry on the true density of formed pellets and also find the optimal conditions of the densification process for producing pellets with high density. Compost was extruded into cylindrical pellets utilizing open-end dies under axial stress from a vertical piston applied by a hydraulic press. The effects of independent variables, including the raw material moisture content (35 to 45% (wet basis, hammer mill screen size (0.3 to 1.5 mm, speed of piston (2 to 10 mm/s, and die length (8 to 12 mm on pellet density, were determined using response surface methodology. A quadratic model was proposed to predict the pellet density, which had high F and R2 values along with a low p value, indicating the predictability of the model. Moisture content, speed of piston, and particle size significantly affected (P 0.05.

  17. Research on high density and safety LiCoO2 as cathode materials for lithium ion batteries

    Institute of Scientific and Technical Information of China (English)

    CHEN; Yan-bin; LIU; Ya-fei; BAI; Hou-shan

    2005-01-01

    Three LiCoO2 samples of different specifications were synthesized using different Co3O4 s as starting material, and characterized in physical, electrochemical and safety properties. There demonstrates clear dependence of LiCoO2 on Co3O4 in particle size and density. The main difference among the three LiCoO2 samples lies in physical, rate capability and safety properties, the sample with larger particle size, higher density (accordingly smaller surface area) demonstrates better safety but lower rate capability, while there is little difference among them in terms of capacity and cycling stability despite of the variation in physical properties.

  18. Computational Design of Non-natural Sugar Alcohols to Increase Thermal Storage Density: Beyond Existing Organic Phase Change Materials.

    Science.gov (United States)

    Inagaki, Taichi; Ishida, Toyokazu

    2016-09-14

    Thermal storage, a technology that enables us to control thermal energy, makes it possible to reuse a huge amount of waste heat, and materials with the ability to treat larger thermal energy are in high demand for energy-saving societies. Sugar alcohols are now one promising candidate for phase change materials (PCMs) because of their large thermal storage density. In this study, we computationally design experimentally unknown non-natural sugar alcohols and predict their thermal storage density as a basic step toward the development of new high performance PCMs. The non-natural sugar alcohol molecules are constructed in silico in accordance with the previously suggested molecular design guidelines: linear elongation of a carbon backbone, separated distribution of OH groups, and even numbers of carbon atoms. Their crystal structures are then predicted using the random search method and first-principles calculations. Our molecular simulation results clearly demonstrate that the non-natural sugar alcohols have potential ability to have thermal storage density up to ∼450-500 kJ/kg, which is significantly larger than the maximum thermal storage density of the present known organic PCMs (∼350 kJ/kg). This computational study suggests that, even in the case of H-bonded molecular crystals where the electrostatic energy contributes mainly to thermal storage density, the molecular distortion and van der Waals energies are also important factors to increase thermal storage density. In addition, the comparison between the three eight-carbon non-natural sugar alcohol isomers indicates that the selection of preferable isomers is also essential for large thermal storage density.

  19. High-density 3D graphene-based monolith and related materials, methods, and devices

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Charnvanichborikarn, Supakit; Kucheyev, Sergei; Montalvo, Elizabeth; Shin, Swanee; Tylski, Elijah

    2017-03-21

    A composition comprising at least one high-density graphene-based monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds and having a density of at least 0.1 g/cm.sup.3. Also provided is a method comprising: preparing a reaction mixture comprising a suspension and at least one catalyst, said suspension selected from a graphene oxide (GO) suspension and a carbon nanotube suspension; curing the reaction mixture to produce a wet gel; drying the wet gel to produce a dry gel, said drying step is substantially free of supercritical drying and freeze drying; and pyrolyzing the dry gel to produce a high-density graphene-based monolith. Exceptional combinations of properties are achieved including high conductive and mechanical properties.

  20. High-density 3D graphene-based monolith and related materials, methods, and devices

    Science.gov (United States)

    Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Charnvanichborikarn, Supakit; Kucheyev, Sergei; Montalvo, Elizabeth; Shin, Swanee; Tylski, Elijah

    2017-03-21

    A composition comprising at least one high-density graphene-based monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds and having a density of at least 0.1 g/cm.sup.3. Also provided is a method comprising: preparing a reaction mixture comprising a suspension and at least one catalyst, said suspension selected from a graphene oxide (GO) suspension and a carbon nanotube suspension; curing the reaction mixture to produce a wet gel; drying the wet gel to produce a dry gel, said drying step is substantially free of supercritical drying and freeze drying; and pyrolyzing the dry gel to produce a high-density graphene-based monolith. Exceptional combinations of properties are achieved including high conductive and mechanical properties.

  1. HoneySiC: a new optomechanical material for low-areal cost and density

    Science.gov (United States)

    Goodman, William A.

    2013-09-01

    One of the major problems perceived for deposited silicon carbide mirrors and structures is the cost associated with machining and lightweighting the material to the specifications of a drawing. Molded pedigrees of silicon carbide address these concerns by casting or molding a slurry and prefiring the slurry to make a consolidated and porous greenbody which is relatively soft and not very difficult to machine. The machined greenbody is then infiltrated with molten silicon in an exothermic process that yields a two phase reaction bonded silicon carbide material that must undergo a final machining step. Converted silicon carbide pedigrees machine a graphite or carbon/carbon precursor material to near net shape and then infiltrate the part with gaseous silicon monoxide or molten silicon to convert most or all of the carbon to silicon carbide. Some pedigrees are highly porous, while others may be dense and containing 2 or 3 different phases of material. We have created and demonstrated a new fiber reinforced silicon carbide material that combines the benefits of molding, infiltration and conversion processes. The resulting HoneySiC material requires a minimal amount of machining. HoneySiC material achieves lightweighting of 92% relative to bulk material and net production cost on the order of 38K per square meter (unpolished), less than half of NASA's goal of 100K per square meter.

  2. Evaluation of the Anisotropic Radiative Conductivity of a Low-Density Carbon Fiber Material from Realistic Microscale Imaging

    Science.gov (United States)

    Nouri, Nima; Panerai, Francesco; Tagavi, Kaveh A.; Mansour, Nagi N.; Martin, Alexandre

    2015-01-01

    The radiative heat transfer inside a low-density carbon fiber insulator is analyzed using a three-dimensional direct simulation model. A robust procedure is presented for the numerical calculation of the geometric configuration factor to compute the radiative energy exchange processes among the small discretized surface areas of the fibrous material. The methodology is applied to a polygonal mesh of a fibrous insulator obtained from three-dimensional microscale imaging of the real material. The anisotropic values of the radiative conductivity are calculated for that geometry. The results yield both directional and thermal dependence of the radiative conductivity.

  3. Theoretical Electron Density Distributions for Fe- and Cu-Sulfide Earth Materials: A Connection between Bond Length, Bond Critical Point Properties, Local Energy Densities, and Bonded Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, Gerald V.; Cox, David F.; Rosso, Kevin M.; Ross, Nancy L.; Downs, R. T.; Spackman, M. A.

    2007-03-01

    Bond critical point and local energy density properties together with net atomic charges were calculated for theoretical electron density distributions, F(r), generated for a variety of Fe and Cu metal-sulfide materials with high- and low-spin Fe atoms in octahedral coordination and high-spin Fe atoms in tetrahedral coordination. The electron density, F(rc), the Laplacian, 32F(rc), the local kinetic energy, G(rc), and the oxidation state of Fe increase as the local potential energy density, V(rc), the Fe-S bond lengths, and the coordination numbers of the Fe atoms decrease. The properties of the bonded interactions for the octahedrally coordinated low-spin Fe atoms for pyrite and marcasite are distinct from those for high-spin Fe atoms for troilite, smythite, and greigite. The Fe-S bond lengths are shorter and the values of F(rc) and 32F(rc) are larger for pyrite and marcasite, indicating that the accumulation and local concentration of F(r) in the internuclear region are greater than those involving the longer, high-spin Fe-S bonded interactions. The net atomic charges and the bonded radii calculated for the Fe and S atoms in pyrite and marcasite are also smaller than those for sulfides with high-spin octahedrally coordinated Fe atoms. Collectively, the Fe-S interactions are indicated to be intermediate in character with the low-spin Fe-S interactions having greater shared character than the highspin interactions. The bond lengths observed for chalcopyrite together with the calculated bond critical point properties are consistent with the formula Cu+Fe3+S2. The bond length is shorter and the F(rc) value is larger for the FeS4 tetrahedron displayed by metastable greigite than those displayed by chalcopyrite and cubanite, consistent with a proposal that the Fe atom in greigite is tetravalent. S-S bond paths exist between each of the surface S atoms of adjacent slabs of FeS6 octahedra comprising the layer sulfide smythite, suggesting that the neutral Fe3S4 slabs are

  4. Tilted Magnetic Levitation Enables Measurement of the Complete Range of Densities of Materials with Low Magnetic Permeability.

    Science.gov (United States)

    Nemiroski, Alex; Soh, Siowling; Kwok, Sen Wai; Yu, Hai-Dong; Whitesides, George M

    2016-02-03

    Magnetic levitation (MagLev) of diamagnetic or weakly paramagnetic materials suspended in a paramagnetic solution in a magnetic field gradient provides a simple method to measure the density of small samples of solids or liquids. One major limitation of this method, thus far, has been an inability to measure or manipulate materials outside of a narrow range of densities (0.8 g/cm(3) levitated magnetically. Tilting the MagLev device relative to the gravitational vector enables the magnetic force to be decreased (relative to the magnetic force) along the axis of measurement. This approach enables many practical measurements over the entire range of densities observed in matter at ambient conditions-from air bubbles (ρ ≈ 0) to osmium and iridium (ρ ≈ 23 g/cm(3)). The ability to levitate, simultaneously, objects with a broad range of different densities provides an operationally simple method that may find application to forensic science (e.g., for identifying the composition of miscellaneous objects or powders), industrial manufacturing (e.g., for quality control of parts), or resource-limited settings (e.g., for identifying and separating small particles of metals and alloys).

  5. Nanostructured Electrode Materials Derived from Metal-Organic Framework Xerogels for High-Energy-Density Asymmetric Supercapacitor.

    Science.gov (United States)

    Mahmood, Asif; Zou, Ruqiang; Wang, Qingfei; Xia, Wei; Tabassum, Hassina; Qiu, Bin; Zhao, Ruo

    2016-01-27

    This work successfully demonstrates metal-organic framework (MOF) derived strategy to prepare nanoporous carbon (NPC) with or without Fe3O4/Fe nanoparticles by the optimization of calcination temperature as highly active electrode materials for asymmetric supercapacitors (ASC). The nanostructured Fe3O4/Fe/C hybrid shows high specific capacitance of 600 F/g at a current density of 1 A/g and excellent capacitance retention up to 500 F/g at 8 A/g. Furthermore, hierarchically NPC with high surface area also obtained from MOF gels displays excellent electrochemical performance of 272 F/g at 2 mV/s. Considering practical applications, aqueous ASC (aASC) was also assembled, which shows high energy density of 17.496 Wh/kg at the power density of 388.8 W/kg. The high energy density and excellent capacity retention of the developed materials show great promise for the practical utilization of these energy storage devices.

  6. High-performance nickel-cobalt-boron material for an asymmetric supercapacitor with an ultrahigh energy density

    Science.gov (United States)

    Chen, Rongna; Liu, Lei; Zhou, Junshuang; Hou, Li; Gao, Faming

    2017-02-01

    Nickel-cobalt-borons are synthesized using a facile and cost-effective reduction method. The effects of Ni/Co molar ratios and crystallinity on its supercapacitive performance are systematically investigated. It was found that nickel-cobalt-borons with the Ni/Co ratio being 2:1 and amorphous structure manifest the optimum specific capacitance of 2226.96 F/g at a current density of 1 A/g and still remain 1879.2 F/g with a high discharge current density of 20 A/g. An asymmetric supercapacitor device (ASC) has been fabricated with nickel-cobalt-borons (Ni-Co-B) as the positive electrode and commercial activated carbon (CAC) as the negative electrode material. The Ni-Co-B//CAC delivers an ultrahigh energy density of 66.40 Wh/kg at a power density of 788.91 W/kg. This ASC remains 85.76% of its initial capacitance even after 5000 charge-discharge cycles. The results demonstrate that amorphous nickel-cobalt-boron material is a promising candidate for energy storage application.

  7. Conductive Polymer Binder for High-Tap-Density Nanosilicon Material for Lithium-Ion Battery Negative Electrode Application.

    Science.gov (United States)

    Zhao, Hui; Wei, Yang; Qiao, Ruimin; Zhu, Chenhui; Zheng, Ziyan; Ling, Min; Jia, Zhe; Bai, Ying; Fu, Yanbao; Lei, Jinglei; Song, Xiangyun; Battaglia, Vincent S; Yang, Wanli; Messersmith, Phillip B; Liu, Gao

    2015-12-09

    High-tap-density silicon nanomaterials are highly desirable as anodes for lithium ion batteries, due to their small surface area and minimum first-cycle loss. However, this material poses formidable challenges to polymeric binder design. Binders adhere on to the small surface area to sustain the drastic volume changes during cycling; also the low porosities and small pore size resulting from this material are detrimental to lithium ion transport. This study introduces a new binder, poly(1-pyrenemethyl methacrylate-co-methacrylic acid) (PPyMAA), for a high-tap-density nanosilicon electrode cycled in a stable manner with a first cycle efficiency of 82%-a value that is further improved to 87% when combined with graphite material. Incorporating the MAA acid functionalities does not change the lowest unoccupied molecular orbital (LUMO) features or lower the adhesion performance of the PPy homopolymer. Our single-molecule force microscopy measurement of PPyMAA reveals similar adhesion strength between polymer binder and anode surface when compared with conventional polymer such as homopolyacrylic acid (PAA), while being electronically conductive. The combined conductivity and adhesion afforded by the MAA and pyrene copolymer results in good cycling performance for the high-tap-density Si electrode.

  8. Tube-Super Dielectric Materials: Electrostatic Capacitors with Energy Density Greater than 200 J·cm−3

    Directory of Open Access Journals (Sweden)

    Francisco Javier Quintero Cortes

    2015-09-01

    Full Text Available The construction and performance of a second generation of super dielectric material based electrostatic capacitors (EC, with energy density greater than 200 J·cm−3, which rival the best reported energy density of electric double layer capacitors (EDLC, also known as supercapacitors, are reported. The first generation super dielectric materials (SDM are multi-material mixtures with dielectric constants greater than 1.0 × 105, composed of a porous, electrically insulating powder filled with a polarizable, ion-containing liquid. Second-generation SDMs (TSDM, introduced here, are anodic titania nanotube arrays filled with concentrated aqueous salt solutions. Capacitors using TiO2 based TSDM were found to have dielectric constants at ~0 Hz greater than 107 in all cases, a maximum operating voltage of greater than 2 volts and remarkable energy density that surpasses the highest previously reported for EC capacitors by approximately one order of magnitude. A simple model based on the classic ponderable media model was shown to be largely consistent with data from nine EC type capacitors employing TSDM.

  9. Temperature Buffer Test. Measurements of water content and density of the excavated buffer material

    Energy Technology Data Exchange (ETDEWEB)

    Johannesson, Lars-Erik [Clay Technology AB, Lund (Sweden)

    2010-12-15

    TBT (Temperature Buffer Test) is a joint project between SKB/ANDRA and supported by ENRESA (modeling) and DBE (instrumentation), which aims at understanding and modeling the thermo-hydromechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test was carried out at the - 420 m level in Aespoe HRL in a 8 meters deep and 1.76 m diameter deposition hole, with two heaters (3 m long, 0.6 m diameter), surrounded by a MX-80 bentonite buffer and a confining plug on top anchored with 9 rods. It was installed during spring 2003. The bentonite around upper heater was removed during the period October - December 2009 and the buffer around the lower heater was removed during January - Mars 2010. During dismantling of the buffer, samples were taken on which analyses were made. This report describes the work with the deteroemoeination of the water content and the density of the taken samples. Most of the samples were taken from the buffer by core drilling from the upper surface of each installed bentonite block. The cores had a diameter of about 50 mm and a maximum length equal to the original height of the bentonite blocks (about 500 mm). The water content of the buffer was determined by drying a sample at a temperature of 105 deg C for 24 h and the bulk density was determined by weighing a sample both in the air and immerged in paraffin oil with known density. The water content, dry density, degree of saturation and void ratio of the buffer were then plotted. The plots show that all parts of the buffer had taken up water and the degree of saturation of the buffer varied between 90 - 100%. Large variation in the dry density of the buffer was also observed.

  10. Quantitative evaluation of metal artifacts using different CBCT devices, high-density materials and field of views.

    Science.gov (United States)

    Codari, Marina; de Faria Vasconcelos, Karla; Ferreira Pinheiro Nicolielo, Laura; Haiter Neto, Francisco; Jacobs, Reinhilde

    2017-04-22

    To objectively compare the influence of different cone-beam computed tomography (CBCT) devices, high-density materials and field of views (FOVs) on metal artifact expression. For this in vitro study, three customized acrylic resin phantoms containing high-density materials cylinders: titanium, copper-aluminum alloy and amalgam were scanned on three CBCT devices using high-resolution protocols, same voxel size (0.2 mm) and different FOVs. After fully automatic segmentation and image registration, the same region of interest was defined for the small and medium FOVs. The difference between the segmented and the real volume of the metal cylinders was assessed. Moreover for each segmented slice, the area difference between the segmented and the real axial section was determined. The artifacts on the background were measured as normalizing standard deviation of voxel values in the vicinity of the cylinder, in three different distances. Considerable differences were observed in volume measurements for all CBCTs devices and materials for both FOV sizes (up to 67%). The slice per slice area analysis indicated higher artifacts at the edges of the metal cylinder. Within the materials, amalgam and titanium had, respectively, the worst and best artifact expression in all the CBCT devices. Standard deviation values varied differently between the three distances in each device. Our in vitro study showed that different CBCT devices, high-density materials and FOV should be considered while evaluating CBCT images. More carefully, diagnosis conclusions should be drawn in images containing amalgam and copper-aluminum alloy. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Density functional theory study of phase stability and defect thermodynamics in iron-oxyhydroxide mineral materials

    Science.gov (United States)

    Pinney, Nathan Douglas

    Due to their high surface area and reactivity toward a variety of heavy metal and oxyanion species of environmental concern, Fe-(oxyhydr)oxide materials play an important role in the geochemical fate of natural and anthropogenic contaminants in soils, aquifers and surface water environments worldwide. In this research, ab initio simulations describe the bulk structure, magnetic properties, and relative phase stability of major Fe-(oxyhydr)oxide materials, including hematite, goethite, lepidocrocite, and ferrihydrite.These bulk models are employed in further studies of point defect and alloy/dopant thermodynamics in these materials, allowing construction of a phase stability model that better replicates the structure and composition of real materials. Li + adsorption at the predominant goethite (101) surface is simulated using ab initio methods, offering energetic and structural insight into the binding mechanisms of metal cations over a range of surface protonation conditions.

  12. Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

    Science.gov (United States)

    Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

    2017-01-01

    Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries. PMID:28443608

  13. Time-domain pumping a quantum-critical charge density wave ordered material

    Science.gov (United States)

    Matveev, O. P.; Shvaika, A. M.; Devereaux, T. P.; Freericks, J. K.

    2016-09-01

    We determine the exact time-resolved photoemission spectroscopy for a nesting driven charge density wave (described by the spinless Falicov-Kimball model within dynamical mean-field theory). The pump-probe experiment involves two light pulses: the first is an ultrashort intense pump pulse that excites the system into nonequilibrium, and the second is a lower amplitude, higher frequency probe pulse that photoexcites electrons. We examine three different cases: the strongly correlated metal, the quantum-critical charge density wave, and the critical Mott insulator. Our results show that the quantum critical charge density wave has an ultraefficient relaxation channel that allows electrons to be de-excited during the pump pulse, resulting in little net excitation. In contrast, the metal and the Mott insulator show excitations that are closer to what one expects from these systems. In addition, the pump field produces spectral band narrowing, peak sharpening, and a spectral gap reduction, all of which rapidly return to their field free values after the pump is over.

  14. Analysis of surface degradation of high density polyethylene (HDPE) insulation material due to tracking

    Indian Academy of Sciences (India)

    R Sarathi; S Chandrasekar; V Sabari Giri; C Venkataseshaiah; R Velmurugan

    2004-06-01

    In the present work, tracking phenomena has been studied with HDPE material under a.c. voltage, with ammonium chloride as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The diffusion coefficient of the material was obtained. The thermal and chemical stability of the material were identified by carrying out a methodical experimental study. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), were carried out and it was concluded that the mechanism of tracking process is due to the surface degradation. The surface condition of the insulation structure was characterized for any surface discharges or tracking, using the leakage current measurement, utilizing the wavelet concepts.

  15. Distributed material density and anisotropy for optimized eigenfrequency of 2D continua

    DEFF Research Database (Denmark)

    Pedersen, Pauli; Pedersen, Niels Leergaard

    2015-01-01

    A practical approach to optimize a continuum/structural eigenfrequency is presented, including design of the distribution of material anisotropy. This is often termed free material optimization (FMO). An important aspect is the separation of the overall material distribution from the local design...... constitutive matrix. For 3D problems from 21 to 6 parameters, for 2D from 6 to 3 parameters, and for axisymmetric problems from 10 to 4 parameters....... are described by non-dimensional matrices with unity norms of trace and Frobenius, and thus this part of the optimized design has no influence on the mass distribution. Gradients of eigenfrequency with respect to the components of these non-dimensional constitutive matrices are therefore simplified...

  16. Density of loose-fill insulation material exposed to cyclic humidity conditions

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    This report presents a proposal for a standardised method for creep tests and the necessary theoretical and empirical framework that can be used to describe creep of granulated loose-fill material exposed to climate. Furthermore results from a round-robin test are shown. The round-robin test...... and Transport in Espoo and the Danish Building Research Institute department of Building Design and Technology. For the round-robin test a cellulosic fibre insulation material was used. The proposed standardised method for creep tests and theoretical and empirical framework are limited to cases when...

  17. Investigation of mud density and weighting materials effect on drilling fluid filter cake properties and formation damage

    Science.gov (United States)

    Fattah, K. A.; Lashin, A.

    2016-05-01

    Drilling fluid density/type is an important factor in drilling and production operations. Most of encountered problems during rotary drilling are related to drilling mud types and weights. This paper aims to investigate the effect of mud weight on filter cake properties and formation damage through two experimental approaches. In the first approach, seven water-based drilling fluid samples with same composition are prepared with different densities (9.0-12.0 lb/gal) and examined to select the optimum mud weight that has less damage. The second approach deals with investigating the possible effect of the different weighting materials (BaSO4 and CaCO3) on filter cake properties. High pressure/high temperature loss tests and Scanning Electron Microscopy (SEM) analyses were carried out on the filter cake (two selected samples). Data analysis has revealed that mud weigh of 9.5 lb/gal has the less reduction in permeability of ceramic disk, among the seven used mud densities. Above 10.5 ppg the effect of the mud weight density on formation damage is stabilized at constant value. Fluids of CaCO3-based weighting material, has less reduction in the porosity (9.14%) and permeability (25%) of the filter disk properties than the BaSO4-based fluid. The produced filter cake porosity increases (from 0.735 to 0.859) with decreasing of fluid density in case of drilling samples of different densities. The filtration loss tests indicated that CaCO3 filter cake porosity (0.52) is less than that of the BaSO4 weighted material (0.814). The thickness of the filter cake of the BaSO4-based fluid is large and can cause some problems. The SEM analysis shows that some major elements do occur on the tested samples (Ca, Al, Si, and Ba), with dominance of Ca on the expense of Ba for the CaCO3 fluid sample and vice versa. The less effect of 9.5 lb/gal mud sample is reflected in the well-produced inter-particle pore structure and relatively crystal size. A general recommendation is given to

  18. Density Functional Theory Simulations Predict New Materials for Magnesium-Ion Batteries (Fact Sheet), NREL Highlights, Science

    Energy Technology Data Exchange (ETDEWEB)

    2011-10-01

    Multivalence is identified in the light element, B, through structure morphology. Boron sheets exhibit highly versatile valence, and the layered boron materials may hold the promise of a high-energy-density magnesium-ion battery. Practically, boron is superior to previously known multivalence materials, especially transition metal compounds, which are heavy, expensive, and often not benign. Based on density functional theory simulations, researchers at the National Renewable Energy Laboratory (NREL) have predicted a series of stable magnesium borides, MgB{sub x}, with a broad range of stoichiometries, 2 < x < 16, by removing magnesium atoms from MgB{sub 2}. The layered boron structures are preserved through an in-plane topological transformation between the hexagonal lattice domains and the triangular domains. The process can be reversibly switched as the charge transfer changes with Mg insertion/extraction. The mechanism of such a charge-driven transformation originates from the versatile valence state of boron in its planar form. The discovery of these new physical phenomena suggests the design of a high-capacity magnesium-boron battery with theoretical energy density 876 mAh/g and 1550 Wh/L.

  19. High-Energy-Density LCA-Coupled Structural Energetic Materials for Counter WMD Applications

    Science.gov (United States)

    2014-04-01

    morphology , etc.) of reactants. In the case of the equivolumetric Ta+Fe2O3 powder mixtures, pre-densification results in generating Fe2O3 as the more...published in the following papers. • N.N. Thadhani and J.K. Cochran, "Energetic Materials", DTRA Basic and Applied Research Program Newsletter , V2, N3, p

  20. The influence of increasing riverbank vegetation density on bed shear stresses and transport of bed material

    Science.gov (United States)

    Liu, Da; Valyrakis, Manousos

    2017-04-01

    Riverbank vegetation can significantly influence the hydrodynamics of the river, such as flow velocity and bed shear stress, as well as affecting geomorphic processes across it. The aim of this study is to report preliminary results from extensive set of experiments aiming to better establish the link between flow and solid transport processes at the vicinity of the riverbank. A set of laboratory experiments is conducted in a recirculating flume with a series of acrylic panels mounted on the side of the flume at an angle to simulate the riverbank, and a large number of acrylic rods placed on top of it simulating riparian vegetation. Ten different vegetation configurations are examined, for the range of vegetation densities found in natural river systems. Three of these are configured in linear arrangement; another three of them in staggered; and the other four follow a random configuration at chosen densities. Turbulent flow is measured across the channel using acoustic Doppler velocimetry (ADV) along a dense measurement grid. The measurements covered the whole cross-section of the channel at the main measurement plane, as well as the riverbank region. The results reported include mean streamwise flow velocity and turbulent intensity profiles, bed shear stresses, momentum transfer at the riverbank region. These are associated with transport metrics obtained using an instrumented tracer particle entrained from different release locations (both from the centerline of the main channel and the near bank region). The results show that the flow velocity at the riverbank reduces with increasing densities of riparian vegetation, while they increase at the main channel. Likewise, the bed shear stresses increased at the main channel, and decreased within the vegetated riverbank, which is replicated by the observations from the particle transport experiments.

  1. High-density polyethylene pipe: A new material for pass-by passive integrated transponder antennas

    Science.gov (United States)

    Kazyak, David C.; Zydlewski, Joseph

    2012-01-01

    Pass-by passive integrated transponder (PIT) antennas are widely used to study the movements of fish in streams. At many sites, stream conditions make it difficult to maintain antennas and obtain a continuous record of movement. We constructed pass-by PIT antennas by using high-density polyethylene (HDPE) and found them to be robust to high flows and winter ice flows. Costs for HDPE antennas were similar to those of traditional polyvinyl chloride (PVC) antennas, although construction was somewhat more complicated. At sites where PVC antennas are frequently damaged, HDPE is a durable and economical alternative for PIT antenna construction.

  2. Free-space reflection method for measuring moisture content and bulk density of particulate materials at microwave frequency

    Science.gov (United States)

    Li, Chenxiao; Han, Bing; Zhang, Tao

    2015-03-01

    A measurement system based on free-space reflection method is designed for simultaneous and independent determination of moisture content and bulk density of particulate materials. The proposed system consists of microwave cavity oscillator, horn antenna, slide rail, sample holder, mixer, and digital meter. Sand and rice with different moisture contents and bulk densities are chosen as samples. Calibration models for moisture content and bulk density are proposed according to the measurement of the position of the minimum of the traveling-standing wave and the ratio of the maximum-to-minimum field strength of the traveling-standing wave at different temperatures. The moisture constant, ranging from 0% to 24.6%, is obtained with a coefficient of determination (R2) greater than 0.982 and a standard error of prediction (SEP) value of less than 0.695%. The bulk density, ranging from 0.501 g/cm3 to 1.822 g/cm3, is determined with a R2 ≥ 0.961 and a SEP value ranging from 0.0144 g/cm3 to 0.0382 g/cm3 for different samples.

  3. Interface structure of Ag(111)/SnO2(200) composite material studied by density functional theory

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Electric contact material of Ag/SnO2 was successfully synthesized by in situ process method.The in-terface structure was characterized by high-resolution transmission electron microscopy(HTEM) and simulated at atomic scale on computer.The mean-square displacements of atoms near the interface were calculated,and the results showed that near the interface both Ag side and SnO2 were mis-matched and this effect decays rapidly far from the interface.By inspecting the calculated density of states(DOS),we found that the electric-conductivity of this composite material was decreased because of the localized 4d and 2p electrons of Ag and O near the Fermi surface,respectively.Electron density changed acutely across the interface,so that there was no extra compound precipitated.A mi-cro-electric field also formed in the whole material due to the interface structure,and this may affect the electron conduction and the related electric-conductivity of the composite.It is found that the interface cohesive energy of Ag(111)/SnO2(200) was-3.50 J/m2,which is higher than the experimental results.

  4. A tunneling current density model for ultra thin HfO2 high-k dielectric material based MOS devices

    Science.gov (United States)

    Maity, Niladri Pratap; Maity, Reshmi; Thapa, R. K.; Baishya, Srimanta

    2016-07-01

    In this paper, an analytical model for evaluation of tunneling current density of ultra thin MOS devices is presented. The impacts of the promising high-k dielectric material, HfO2 on the current density model have been carried out. In this work, improvement in the results is brought in by taking into account the barrier height lowering due to the image force effect. The considered voltage range is from 0 to ψ1/e i.e., 0 neglecting the image force effect for a MOS device consisting asymmetric barrier. Later, image force effect of ultra thin oxide layer has been introduced for practical potential barrier by superimposing the potential barrier on the trapezoidal barrier. Theoretical predictions are compared with the results obtained by the 2-D numerical device simulator ATLAS and published experimental results. Excellent agreements among the three are observed.

  5. High-T{sub c} superconductor/linear low density polyethylene (LLDPE) composite materials for diamagnetic applications

    Energy Technology Data Exchange (ETDEWEB)

    Bhadrakumari, S [Department of Physics, St. Berchman' s College, Changanassery, Kerala (India); Predeep, P [Condensed Matter Physics Laboratory, Department of Physics, Sree Narayana College, Kollam 691 001, Kerala (India)

    2006-08-15

    A series of composite samples of YBa{sub 2}Cu{sub 3}O{sub 7-x} and linear low density polyethylene (Y-123/LLDPE) with volume percentage ranging from 0 to 75% was prepared. The crystallinity of the composites was studied using x-ray diffraction (XRD) patterns. It is found that the percentage of crystallinity in the composite samples increases with increasing volume of the LLDPE. A four-phase system for the composite materials may be inferred from a combination of XRD and density data. Repulsive force measurements showed that the diamagnetic properties were preserved in the composites and the samples exhibited appreciable magnetic levitation forces and this force increases with increasing volume fraction of the superconductor filler.

  6. High-Pressure Preparation of High-Density Cu2ZnSnS4 Materials

    Science.gov (United States)

    Yi-Ming, Li; Li-Xia, Qiu; Zhan-Hui, Ding; Yong-Feng, Li; Bin, Yao; Zhen-Yu, Xiao; Pin-Wen, Zhu

    2016-07-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 10874178, 11074093, 61205038 and 11274135, the National Found for Fostering Talents of Basic Science under Grant No J1103202, the Ph.D. Programs Foundation of Ministry of Education of China under Grant No 20120061120011, the Open Project of State Key Laboratory of Superhard Materials of Jilin University, and the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry of Jilin University.

  7. Combining density functional theory calculations, supercomputing, and data-driven methods to design new materials (Conference Presentation)

    Science.gov (United States)

    Jain, Anubhav

    2017-04-01

    Density functional theory (DFT) simulations solve for the electronic structure of materials starting from the Schrödinger equation. Many case studies have now demonstrated that researchers can often use DFT to design new compounds in the computer (e.g., for batteries, catalysts, and hydrogen storage) before synthesis and characterization in the lab. In this talk, I will focus on how DFT calculations can be executed on large supercomputing resources in order to generate very large data sets on new materials for functional applications. First, I will briefly describe the Materials Project, an effort at LBNL that has virtually characterized over 60,000 materials using DFT and has shared the results with over 17,000 registered users. Next, I will talk about how such data can help discover new materials, describing how preliminary computational screening led to the identification and confirmation of a new family of bulk AMX2 thermoelectric compounds with measured zT reaching 0.8. I will outline future plans for how such data-driven methods can be used to better understand the factors that control thermoelectric behavior, e.g., for the rational design of electronic band structures, in ways that are different from conventional approaches.

  8. Scalable real space pseudopotential-density functional codes for materials applications

    Science.gov (United States)

    Chelikowsky, James R.; Lena, Charles; Schofield, Grady; Saad, Yousef; Deslippe, Jack; Yang, Chao

    2015-03-01

    Real-space pseudopotential density functional theory has proven to be an efficient method for computing the properties of matter in many different states and geometries, including liquids, wires, slabs and clusters with and without spin polarization. Fully self-consistent solutions have been routinely obtained for systems with thousands of atoms. However, there are still systems where quantum mechanical accuracy is desired, but scalability proves to be a hindrance, such as large biological molecules or complex interfaces. We will present an overview of our work on new algorithms, which offer improved scalability by implementing another layer of parallelism, and by optimizing communication and memory management. Support provided by the SciDAC program, Department of Energy, Office of Science, Advanced Scientific Computing Research and Basic Energy Sciences. Grant Numbers DE-SC0008877 (Austin) and DE-FG02-12ER4 (Berkeley).

  9. Relativistic plasma optics enabled by near-critical density nanostructured material

    CERN Document Server

    Bin, J H; Wang, H Y; Streeter, M J V; Kreuzer, C; Kiefer, D; Yeung, M; Cousens, S; Foster, P S; Dromey, B; Yan, X Q; Meyer-ter-Vehn, J; Zepf, M; Schreiber, J

    2014-01-01

    The nonlinear optical properties of a plasma due to the relativistic electron motion in an intense laser field are of fundamental importance for current research and the generation of brilliant laser-driven sources of particles and photons1-15. Yet, one of the most interesting regimes, where the frequency of the laser becomes resonant with the plasma, has remained experimentally hard to access. We overcome this limitation by utilizing ultrathin carbon nanotube foam16 (CNF) targets allowing the strong relativistic nonlinearities at near- critical density (NCD) to be exploited for the first time. We report on the experimental realization of relativistic plasma optics to spatio-temporally compress the laser pulse within a few micrometers of propagation, while maintaining about half its energy. We also apply the enhanced laser pulses to substantially improve the properties of an ion bunch accelerated from a secondary target. Our results provide first insights into the rich physics of NCD plasmas and the opportuni...

  10. Crystal structure of the high-energy-density material guanylurea dipicrylamide

    Directory of Open Access Journals (Sweden)

    Raik Deblitz

    2014-08-01

    Full Text Available The title compound, 1-carbamoylguanidinium bis(2,4,6-trinitrophenylamide [H2NC(=ONHC(NH22]+[N{C6H2(NO23-2,4,6}2]− (= guanylurea dipicrylamide, was prepared as dark-red block-like crystals in 70% yield by salt-metathesis reaction between guanylurea sulfate and sodium dipicrylamide. In the solid state, the new compound builds up an array of mutually linked guanylurea cations and dipicrylamide anions. The crystal packing is dominated by an extensive network of N—H...O hydrogen bonds, resulting in a high density of 1.795 Mg m−3, which makes the title compound a potential secondary explosive.

  11. Crystal structure of the high-energy-density material guanylurea dipicryl-amide.

    Science.gov (United States)

    Deblitz, Raik; Hrib, Cristian G; Hilfert, Liane; Edelmann, Frank T

    2014-08-01

    The title compound, 1-carbamoylguanidinium bis-(2,4,6-tri-nitro-phen-yl)amide [H2NC(=O)NHC(NH2)2](+)[N{C6H2(NO2)3-2,4,6}2](-) (= guanylurea dipicryl-amide), was prepared as dark-red block-like crystals in 70% yield by salt-metathesis reaction between guanylurea sulfate and sodium dipicryl-amide. In the solid state, the new compound builds up an array of mutually linked guanylurea cations and dipicryl-amide anions. The crystal packing is dominated by an extensive network of N-H⋯O hydrogen bonds, resulting in a high density of 1.795 Mg m(-3), which makes the title compound a potential secondary explosive.

  12. High Torque Density Transverse Flux Machine without the Need to Use SMC Material for 3D Flux Paths

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Wu, Weimin

    2015-01-01

    This paper presents a new transverse flux permanent magnet machine. In a normal transverse flux machine, complicated 3-D flux paths often exist. Such 3-D flux paths would require the use of soft magnetic composites material instead of laminations for construction of the machine stator. In the new...... machine topology proposed in this paper, by advantageously utilizing the magnetic flux path provided by an additional rotor, use of laminations that allow 2-D flux paths only will be sufficient to accomplish the required 3-D flux paths. The machine also has a high torque density and is therefore...

  13. Density Functional Theory Meta-GGA+U Study of Water Incorporation in the Metal Organic Framework Material Cu-BTC

    OpenAIRE

    Cockayne, Eric; Nelson, Eric B.

    2015-01-01

    Water absorption in the metal-organic framework (MOF) material Cu-BTC, up to a concentration of 3.5 H$_2$O per Cu ion, is studied via density functional theory at the meta-GGA+U level. The stable arrangements of water molecules show chains of hydrogen-bonded water molecules and a tendency to form closed cages at high concentration. Water clusters are stabilized primarily by a combination of water-water hydrogen bonding and Cu-water oxygen interactions. Stability is further enhanced by van der...

  14. Comparative studies on physico-mechanical properties of composite materials of low density polyethylene and raw/calcined kaolin

    Directory of Open Access Journals (Sweden)

    Amit Mallik

    2015-06-01

    Full Text Available The paper describes the preparation of the composite materials of low density polyethylene (LDPE as the base mixed separately with raw kaolin and the same calcined at 800 °C under the same variation in weight percentage using single-screw extruder and a mixing machine operated at a temperature between 190 and 200 °C. Some of the mechanical and physical properties such as Young's modulus, elongation at break, shore hardness and water absorption were determined at different weight fractions of filler (0, 2, 7, 10 and 15%. It was found that the addition of filler increases the mechanical properties. Absorption test was done in water at different immersion times for different composites. The degree of water absorption of composite materials was found to decrease with increasing wt% of kaolin filler (0–15% according to Fick's law. Calcined kaolin produces better mechanical properties than raw kaolin.

  15. A chemistry and material perspective on lithium redox flow batteries towards high-density electrical energy storage.

    Science.gov (United States)

    Zhao, Yu; Ding, Yu; Li, Yutao; Peng, Lele; Byon, Hye Ryung; Goodenough, John B; Yu, Guihua

    2015-11-21

    Electrical energy storage system such as secondary batteries is the principle power source for portable electronics, electric vehicles and stationary energy storage. As an emerging battery technology, Li-redox flow batteries inherit the advantageous features of modular design of conventional redox flow batteries and high voltage and energy efficiency of Li-ion batteries, showing great promise as efficient electrical energy storage system in transportation, commercial, and residential applications. The chemistry of lithium redox flow batteries with aqueous or non-aqueous electrolyte enables widened electrochemical potential window thus may provide much greater energy density and efficiency than conventional redox flow batteries based on proton chemistry. This Review summarizes the design rationale, fundamentals and characterization of Li-redox flow batteries from a chemistry and material perspective, with particular emphasis on the new chemistries and materials. The latest advances and associated challenges/opportunities are comprehensively discussed.

  16. Theoretical Study of the N-NO2 Bond Dissociation Energies for Energetic Materials with Density Functional Theory

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Hong; TANG Zheng-Xin; Abraham F.Jalbout; ZHANG Xian-Zhou; CHENG Xin-Lu

    2008-01-01

    The N-NO2 bond dissociation energies (BDEs) for 7 energetic materials were computed by means of accurate density functional theory (B3LYP, B3PW91 and B3P86) with 6-31G** and 6-311G** basis sets. By comparing the computed energies and experimental results, we find that the B3P86/6-311G** method can give good results of BDE, which has the mean absolute deviation of 1.30 kcal/mol. In addition, substituent effects were also taken into account. It is noted that the Hammett constants of substituent groups are related to the BDEs of the N-NO2 bond and the bond dissociation energies of the energetic materials studied decrease when increasing the number of NO2 group.

  17. Scalable real space pseudopotential density functional codes for materials in the exascale regime

    Science.gov (United States)

    Lena, Charles; Chelikowsky, James; Schofield, Grady; Biller, Ariel; Kronik, Leeor; Saad, Yousef; Deslippe, Jack

    Real-space pseudopotential density functional theory has proven to be an efficient method for computing the properties of matter in many different states and geometries, including liquids, wires, slabs, and clusters with and without spin polarization. Fully self-consistent solutions using this approach have been routinely obtained for systems with thousands of atoms. Yet, there are many systems of notable larger sizes where quantum mechanical accuracy is desired, but scalability proves to be a hindrance. Such systems include large biological molecules, complex nanostructures, or mismatched interfaces. We will present an overview of our new massively parallel algorithms, which offer improved scalability in preparation for exascale supercomputing. We will illustrate these algorithms by considering the electronic structure of a Si nanocrystal exceeding 104 atoms. Support provided by the SciDAC program, Department of Energy, Office of Science, Advanced Scientific Computing Research and Basic Energy Sciences. Grant Numbers DE-SC0008877 (Austin) and DE-FG02-12ER4 (Berkeley).

  18. Device Architecture and Materials for Organic Light-Emitting Devices Targeting High Current Densities and Control of the Triplet Concentration

    CERN Document Server

    Schols, Sarah

    2011-01-01

    Device Architecture and Materials for Organic Light-Emitting Devices focuses on the design of new device and material concepts for organic light-emitting devices, thereby targeting high current densities and an improved control of the triplet concentration. A new light-emitting device architecture, the OLED with field-effect electron transport, is demonstrated. This device is a hybrid between a diode and a field-effect transistor. Compared to conventional OLEDs, the metallic cathode is displaced by one to several micrometers from the light-emitting zone, reducing optical absorption losses. The electrons injected by the cathode accumulate at an organic heterojunction and are transported to the light-emission zone by field-effect. High mobilities for charge carriers are achieved in this way, enabling a high current density and a reduced number of charge carriers in the device. Pulsed excitation experiments show that pulses down to 1 µs can be applied to this structure without affecting the light intensity, sug...

  19. Tomography of atomic number and density of materials using dual-energy imaging and the Alvarez and Macovski attenuation model

    Science.gov (United States)

    Paziresh, M.; Kingston, A. M.; Latham, S. J.; Fullagar, W. K.; Myers, G. M.

    2016-06-01

    Dual-energy computed tomography and the Alvarez and Macovski [Phys. Med. Biol. 21, 733 (1976)] transmitted intensity (AMTI) model were used in this study to estimate the maps of density (ρ) and atomic number (Z) of mineralogical samples. In this method, the attenuation coefficients are represented [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)] in the form of the two most important interactions of X-rays with atoms that is, photoelectric absorption (PE) and Compton scattering (CS). This enables material discrimination as PE and CS are, respectively, dependent on the atomic number (Z) and density (ρ) of materials [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)]. Dual-energy imaging is able to identify sample materials even if the materials have similar attenuation coefficients at single-energy spectrum. We use the full model rather than applying one of several applied simplified forms [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976); Siddiqui et al., SPE Annual Technical Conference and Exhibition (Society of Petroleum Engineers, 2004); Derzhi, U.S. patent application 13/527,660 (2012); Heismann et al., J. Appl. Phys. 94, 2073-2079 (2003); Park and Kim, J. Korean Phys. Soc. 59, 2709 (2011); Abudurexiti et al., Radiol. Phys. Technol. 3, 127-135 (2010); and Kaewkhao et al., J. Quant. Spectrosc. Radiat. Transfer 109, 1260-1265 (2008)]. This paper describes the tomographic reconstruction of ρ and Z maps of mineralogical samples using the AMTI model. The full model requires precise knowledge of the X-ray energy spectra and calibration of PE and CS constants and exponents of atomic number and energy that were estimated based on fits to simulations and calibration measurements. The estimated ρ and Z images of the samples used in this paper yield average relative errors of 2.62% and 1.19% and maximum relative errors of 2.64% and 7.85%, respectively. Furthermore, we demonstrate that the method accounts for the beam hardening effect in density (ρ) and

  20. Structural materialization of stainless steel molds and dies by the low temperature high density plasma nitriding

    Directory of Open Access Journals (Sweden)

    Aizawa Tatsuhiko

    2015-01-01

    Full Text Available Various kinds of stainless steels have been widely utilized as a mold substrate material for injection molding and as a die for mold-stamping and direct stamping processes. Since they suffered from high temperature transients and thermal cycles in practice, they must be surface-treated by dry and wet coatings, or, by plasma nitriding. Martensitic stainless steel mold was first wet plated by the nickel phosphate (NiP, which was unstable at the high temperature stamping condition; and, was easy to crystalize or to fracture by itself. This issue of nuisance significantly lowered the productivity in fabrication of optical elements at present. In the present paper, the stainless steel mold was surface-treated by the low-temperature plasma nitriding. The nitrided layer by this surface modification had higher nitrogen solute content than 4 mass%; the maximum solid-solubility of nitrogen is usually 0.1 mass% in the equilibrium phase diagram. Owing to this solid-solution with high nitrogen concentration, the nitrided layer had high hardness of 1400 Hv within its thickness of 40 μm without any formation of nitrides after 14.4 ks plasma nitriding at 693 K. This nitrogen solid-solution treated stainless steel had thermal resistivity even at the mold-stamping conditions up to 900 K.

  1. Furazans with Azo Linkages: Stable CHNO Energetic Materials with High Densities, Highly Energetic Performance, and Low Impact and Friction Sensitivities.

    Science.gov (United States)

    Qu, Yanyang; Zeng, Qun; Wang, Jun; Ma, Qing; Li, Hongzhen; Li, Haibo; Yang, Guangcheng

    2016-08-22

    Various highly energetic azofurazan derivatives were synthesized by simple and efficient chemical routes. These nitrogen-rich materials were fully characterized by FTIR spectroscopy, elemental analysis, multinuclear NMR spectroscopy, and high-resolution mass spectrometry. Four of them were further confirmed structurally by single-crystal X-ray diffraction. These compounds exhibit high densities, ranging from 1.62 g cm(-3) up to a remarkably high 2.12 g cm(-3) for nitramine-substituted azofurazan DDAzF (2), which is the highest yet reported for an azofurazan-based CHNO energetic compound and is a consequence of the formation of strong intermolecular hydrogen-bonding networks. From the heats of formation, calculated with Gaussian 09, and the experimentally determined densities, the energetic performances (detonation pressure and velocities) of the materials were ascertained with EXPLO5 v6.02. The results suggest that azofurazan derivatives exhibit excellent detonation properties (detonation pressures of 21.8-46.1 GPa and detonation velocities of 6602-10 114 m s(-1) ) and relatively low impact and friction sensitivities (6.0-80 J and 80-360 N, respectively). In particular, they have low electrostatic spark sensitivities (0.13-1.05 J). These properties, together with their high nitrogen contents, make them potential candidates as mechanically insensitive energetic materials with high-explosive performance. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Nano-sized structured layered positive electrode materials to enable high energy density and high rate capability lithium batteries

    Science.gov (United States)

    Deng, Haixia; Belharouak, Ilias; Amine, Khalil

    2012-10-02

    Nano-sized structured dense and spherical layered positive active materials provide high energy density and high rate capability electrodes in lithium-ion batteries. Such materials are spherical second particles made from agglomerated primary particles that are Li.sub.1+.alpha.(Ni.sub.xCo.sub.yMn.sub.z).sub.1-tM.sub.tO.sub.2-dR.sub.d- , where M is selected from can be Al, Mg, Fe, Cu, Zn, Cr, Ag, Ca, Na, K, In, Ga, Ge, V, Mo, Nb, Si, Ti, Zr, or a mixture of any two or more thereof, R is selected from F, Cl, Br, I, H, S, N, or a mixture of any two or more thereof, and 0.ltoreq..alpha..ltoreq.0.50; 0materials and their use in electrochemical devices are also described.

  3. Fabrication and materials properties of high-density polyethylene (HDPE)/biphasic calcium phosphate (BCP) hybrid bone plates

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Sun Young; Youn, Min Ho; Lim, Youn Mook; Gwon, Hui Jeong; Park, Jong Seok; Nho, Young Chang [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2010-06-15

    Biphasic calcium phosphate-reinforced high-density polyethylene (BCP/HDPE) hybrid composite is a new orthopedic biomaterial, which was made to simulate a natural bone composition. Calcium phosphate systems and HDPE hybrid composites have been used in biomedical applications without any inflammatory response. Differences in natural bone of both materials have motivated the use of coupling agents to improve their interfacial interfacial interactions. The composites were prepared using medical grade BCP powder and granular polyethylene. This material was produced by replacing the mineral component and collagen soft tissue of the bone with BCP and HDPE, respectively. As expected, increased volume fraction of either reinforcement type over 0 {approx} 50 vol.% resulted in a increased Vickers hardness and Young's modulus. Thus, BCP particle-reinforced HDPE composites possessed improved material and mechanical properties. BCP particles-reinforced composites were anisotropic due to an alignment of the particles in the matrix during a processing. On the other hand, bending and tensile strength was dramatically changed in the matrix. To change the material and mechanical properties of HDPE/BCP composites, the process of a blending was used, and its effect on the microstructure and mechanical proprieties of HDPE/BCP composites were investigated by means of FT-IR/ATR spectroscopy, XRD, FE-SEM, Vickers Hardness Testing Machine, Universal Testing Machine, Mercury Porosimeter and Ultrasonic Flaw Detector at room temperature. For the evaluation of the cell viability and proliferation onto the external surface of HDPE/BCP hybrid plates with a HaCaT cell line, which is a multipotent cell line able to differentiate towards different phenotypes under the action of biological factors, has been evaluated with in vitro studies and quantified by colormetric assays. These findings indicate that the HDPE/BCP hybrid plates are biocompatible and non-toxic.

  4. Correlation between Cohesive Energy Density, Fractional Free Volume, and Gas Transport Properties of Poly(ethylene-co-vinyl acetate Materials

    Directory of Open Access Journals (Sweden)

    Piotr Kubica

    2015-01-01

    Full Text Available The transport properties of the poly(ethylene-co-vinyl acetate (EVA materials to He, N2, O2, and CO2 are correlated with two polymer molecular structure parameters, that is, cohesive energy density (CED and fractional free volume (FFV, determined by the group contribution method. In our preceding paper, the attempt was made to approximate EVA permeability using a linear function of 1/FFV as predicted by the free volume theory. However, the deviations from this relationship appeared to be significant. In this paper, it is shown that permeation of gas molecules is controlled not only by free volume but also by the polymer cohesive energy. Moreover, the behavior of CO2 was found to differ significantly from that of other gases. In this instance, the correlation is much better when diffusivity instead of permeability is taken into account in a modified transport model.

  5. Investigation of nano-talc as a filling material and a reinforcing agent in high density polyethylene (HDPE)

    Institute of Scientific and Technical Information of China (English)

    CHEN Nanchun; MA Lei; ZHANG Tao

    2006-01-01

    An experiment of producing high density polyethylene (HDPE) nano-composite filled with 4wt.% talc was presented. Acting as filler and a reinforcing agent in the HDPE, talc powder, sized at around 5 μm, was surface-treated with aluminum diethylene glycol dinitrate coupling agent before adding to the HDPE. Analyses of the reinforced HDPE nano-composite show significant improvement in its mechanical properties including, tensile strength (>26 MPa), break elongation (<1.1%), flexural strength (>22 MPa), and friction coefficients<0.11. The results demonstrate that, after surface-treated, talc can be used as a promising filling material and a reinforcing agent in making HDPE nano-composite.

  6. Relationship between anode material, supporting electrolyte and current density during electrochemical degradation of organic compounds in water.

    Science.gov (United States)

    Guzmán-Duque, Fernando L; Palma-Goyes, Ricardo E; González, Ignacio; Peñuela, Gustavo; Torres-Palma, Ricardo A

    2014-08-15

    Taking crystal violet (CV) dye as pollutant model, the electrode, electrolyte and current density (i) relationship for electro-degrading organic molecules is discussed. Boron-doped diamond (BDD) or Iridium dioxide (IrO2) used as anode materials were tested with Na2SO4 or NaCl as electrolytes. CV degradation and generated oxidants showed that degradation pathways and efficiency are strongly linked to the current density-electrode-electrolyte interaction. With BDD, the degradation pathway depends on i: If idegraded by OH radicals, whereas if i>i(lim), generated oxidants play a major role in the CV elimination. When IrO2 was used, CV removal was not dependent on i, but on the electrolyte. Pollutant degradation in Na2SO4 on IrO2 seems to occur via IrO3; however, in the presence of NaCl, degradation was dependent on the chlorinated oxidative species generated. In terms of efficiency, the Na2SO4 electrolyte showed better results than NaCl when BDD anodes were employed. On the contrary, NaCl was superior when combined with IrO2. Thus, the IrO2/Cl(-) and BDD/SO4(2-) systems were better at removing the pollutant, being the former the most effective. On the other hand, pollutant degradation with the BDD/SO4(2-) and IrO2/Cl(-) systems is favored at low and high current densities, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Phantom-less bone mineral density (BMD) measurement using dual energy computed tomography-based 3-material decomposition

    Science.gov (United States)

    Hofmann, Philipp; Sedlmair, Martin; Krauss, Bernhard; Wichmann, Julian L.; Bauer, Ralf W.; Flohr, Thomas G.; Mahnken, Andreas H.

    2016-03-01

    Osteoporosis is a degenerative bone disease usually diagnosed at the manifestation of fragility fractures, which severely endanger the health of especially the elderly. To ensure timely therapeutic countermeasures, noninvasive and widely applicable diagnostic methods are required. Currently the primary quantifiable indicator for bone stability, bone mineral density (BMD), is obtained either by DEXA (Dual-energy X-ray absorptiometry) or qCT (quantitative CT). Both have respective advantages and disadvantages, with DEXA being considered as gold standard. For timely diagnosis of osteoporosis, another CT-based method is presented. A Dual Energy CT reconstruction workflow is being developed to evaluate BMD by evaluating lumbar spine (L1-L4) DE-CT images. The workflow is ROI-based and automated for practical use. A dual energy 3-material decomposition algorithm is used to differentiate bone from soft tissue and fat attenuation. The algorithm uses material attenuation coefficients on different beam energy levels. The bone fraction of the three different tissues is used to calculate the amount of hydroxylapatite in the trabecular bone of the corpus vertebrae inside a predefined ROI. Calibrations have been performed to obtain volumetric bone mineral density (vBMD) without having to add a calibration phantom or to use special scan protocols or hardware. Accuracy and precision are dependent on image noise and comparable to qCT images. Clinical indications are in accordance with the DEXA gold standard. The decomposition-based workflow shows bone degradation effects normally not visible on standard CT images which would induce errors in normal qCT results.

  8. Spectroscopic Investigation of the Canopy Configurations in Nanoparticle Organic Hybrid Materials of Various Grafting Densities during CO 2 Capture

    KAUST Repository

    Petit, Camille

    2012-01-12

    Novel liquid-like nanoparticle organic hybrid materials (NOHMs) made of polyetheramine chains tethered onto functionalized silica nanoparticles were synthesized and characterized before and after exposure to CO 2 using NMR, Raman, and ATR FT-IR spectroscopies in order to investigate the effect of the grafting densities on the NOHM canopy structure. Considering the promising tunable properties for CO 2 capture of NOHMs, this study was conducted to provide important structural information to better design NOHMs for CO 2 capture. In order to minimize the CO 2 absorption via enthalpic effect and provide a more accurate assessment of the structural effects, the NOHMs were synthesized without task-specific groups. A greater chain ordering and decreased intermolecular interactions were observed in NOHMs compared to the unbound polymer. This was attributed to the specific structural arrangement of the frustrated canopy. The distinct configuration of grafted polymer chains caused different CO 2 packing and CO 2-induced swelling behaviors between the NOHMs and the unbound polymer. The grafting density influenced the ordering and coupling of the polymer chains and CO 2-induced swelling. Its effect on the CO 2 packing behavior was less pronounced. © 2011 American Chemical Society.

  9. Material characterization and computer model simulation of low density polyurethane foam used in a rodent traumatic brain injury model.

    Science.gov (United States)

    Zhang, Liying; Gurao, Manish; Yang, King H; King, Albert I

    2011-05-15

    Computer models of the head can be used to simulate the events associated with traumatic brain injury (TBI) and quantify biomechanical response within the brain. Marmarou's impact acceleration rodent model is a widely used experimental model of TBI mirroring axonal pathology in humans. The mechanical properties of the low density polyurethane (PU) foam, an essential piece of energy management used in Marmarou's impact device, has not been fully characterized. The foam used in Marmarou's device was tested at seven strain rates ranging from quasi-static to dynamic (0.014-42.86 s⁻¹) to quantify the stress-strain relationships in compression. Recovery rate of the foam after cyclic compression was also determined through the periods of recovery up to three weeks. The experimentally determined stress-strain curves were incorporated into a material model in an explicit Finite Element (FE) solver to validate the strain rate dependency of the FE foam model. Compression test results have shown that the foam used in the rodent impact acceleration model is strain rate dependent. The foam has been found to be reusable for multiple impacts. However the stress resistance of used foam is reduced to 70% of the new foam. The FU_CHANG_FOAM material model in an FE solver has been found to be adequate to simulate this rate sensitive foam.

  10. Relationship between anode material, supporting electrolyte and current density during electrochemical degradation of organic compounds in water

    Energy Technology Data Exchange (ETDEWEB)

    Guzmán-Duque, Fernando L. [Grupo de diagnóstico y control de la contaminación, Facultad de ingeniería, Universidad de Antioquia, A.A. 1226, Medellín (Colombia); Palma-Goyes, Ricardo E. [Grupo de Investigación en Remediación Ambiental y Biocatálisis, Instituto de Química, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquía Udea, A.A. 1226, Medellín (Colombia); González, Ignacio [Universidad Autónoma Metropolitana-Iztapalapa, Departamento de Química, Av. San Rafael Atlixco No 186, C.P 09340, México D.F (Mexico); Peñuela, Gustavo [Grupo de diagnóstico y control de la contaminación, Facultad de ingeniería, Universidad de Antioquia, A.A. 1226, Medellín (Colombia); Torres-Palma, Ricardo A., E-mail: rtorres@matematicas.udea.edu.co [Grupo de Investigación en Remediación Ambiental y Biocatálisis, Instituto de Química, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquía Udea, A.A. 1226, Medellín (Colombia)

    2014-08-15

    Highlights: • Pathway and efficiency are linked to the current-electrode–electrolyte interaction. • Unlike BDD, IrO{sub 2} route was independent of current but dependent on the electrolyte. • IrO{sub 2}/SO{sub 4}{sup 2−} and IrO{sub 2}/Cl{sup −} routes were via IrO{sub 3} and chlorine species, respectively. • BDD/SO{sub 4}{sup 2−} and IrO{sub 2}/Cl{sup −} systems were favored at low and high currents, respectively. - Abstract: Taking crystal violet (CV) dye as pollutant model, the electrode, electrolyte and current density (i) relationship for electro-degrading organic molecules is discussed. Boron-doped diamond (BDD) or Iridium dioxide (IrO{sub 2}) used as anode materials were tested with Na{sub 2}SO{sub 4} or NaCl as electrolytes. CV degradation and generated oxidants showed that degradation pathways and efficiency are strongly linked to the current density-electrode–electrolyte interaction. With BDD, the degradation pathway depends on i: If i < the limiting current density (i{sub lim}), CV is mainly degraded by ·OH radicals, whereas if i > i{sub lim}, generated oxidants play a major role in the CV elimination. When IrO{sub 2} was used, CV removal was not dependent on i, but on the electrolyte. Pollutant degradation in Na{sub 2}SO{sub 4} on IrO{sub 2} seems to occur via IrO{sub 3}; however, in the presence of NaCl, degradation was dependent on the chlorinated oxidative species generated. In terms of efficiency, the Na{sub 2}SO{sub 4} electrolyte showed better results than NaCl when BDD anodes were employed. On the contrary, NaCl was superior when combined with IrO{sub 2}. Thus, the IrO{sub 2}/Cl{sup −} and BDD/SO{sub 4}{sup 2−} systems were better at removing the pollutant, being the former the most effective. On the other hand, pollutant degradation with the BDD/SO{sub 4}{sup 2−} and IrO{sub 2}/Cl{sup −} systems is favored at low and high current densities, respectively.

  11. Low Density Materials

    Science.gov (United States)

    2013-03-07

    Orthogonal transport of phonons for thermal management • Mechanical reinforcement MURI 11: Nanofabrication of 3D Nanotube Architectures 14...in Aerospace Platforms 27 Self-Similar Hierarchical Honeycombs A new class of self-similar ( fractal - appearing) hierarchical honeycombs with a...Optimum topology of hierarchical honeycombs, which approaches the fractal limit. DISTRIBUTION STATEMENT A – Unclassified, Unlimited Distribution 28

  12. Low Density Materials

    Science.gov (United States)

    2012-03-09

    achieve: - Organo -solubility - Structural rigidity and toughness - High thermal stability 6 DISTRIBUTION A: Approved for public release; distribution...unlimited. 1D Carbon Nanotubes 2D Graphene Nanostructured Carbon 0D Fullerene 3D ? 19 DISTRIBUTION A: Approved for public release...distribution is unlimited. MURI 11 Topic: Nanofabrication of 3D Nanotube Architectures Objective: Controlled assembly and atomic-scale bonding of

  13. Far infrared conductivity of charge density wave materials and the oxygen isotope effect in high-T sub c superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Creager, W.N.

    1991-09-01

    The far infrared reflectance and conductivity of (Ta{sub 1-x}Nb{sub x}Se{sub 4}){sub 2}I and TaS{sub 3} have been measured to determine the origin of a huge infrared resonance that dominates the charge density wave (CDW) dynamics along with the pinned acoustic phason mode in the related materials (TaSe{sub 4}){sub 2}I and K{sub 0. 3}MoO{sub 3}. The measurements cover frequencies from 3 to 700cm{sup {minus}1} and the temperature range from 15K to 300K. In the niobium-doped alloys (Ta{sub 1-x}Nb{sub x}Se{sub 4}){sub 2}I, the size and frequency of the giant infrared mode remain nearly constant as the impurity concentration x is increased. For TaS{sub 3}, the pinned acoustic phason near 0.5cm{sup {minus}1} dominates {var epsilon}({omega}) and an additional small mode lies near 9cm{sup {minus}1}. The latter mode is much smaller than the infrared mode in other CDW materials. These results rule out several models of a generic infrared mode'' in CDW excitations. They are compared in detail to the predictions of a recent theory attributing the infrared mode to a bound collective mode localized at impurity sites within the crystal. The transmittance of K{sub 0.3}MoO{sub 3} has been measured at 1.2K with a strong dc electric field applied across the crystal. Under these conditions, the charge density wave depins abruptly and carries large currents with near-zero differential resistance. For some samples, the low-frequency transmittance is enhanced slightly when the CDW depins. The magnitude of the oxygen isotope effect in the high-{Tc} superconductor YBa{sub 2}Cu{sub 3}O{sub 7} has been determined by substitution of {sup 18}O for {sup 16}O. A series of cross-exchanges was performed on high-quality polycrystalline specimens to eliminate uncertainties due to sample heat treatments and sample inhomogeneities.

  14. Single and multiple scattering XAFS Debye-Waller factors for crystalline materials using periodic Density Functional Theory

    Energy Technology Data Exchange (ETDEWEB)

    Dimakis, N; Mion, T [Department of Physics and Geology, University of Texas-Pan American, Edinburg, TX 78539 (United States); Bunker, G, E-mail: dimakis@utpa.ed [Department of Biological Chemical and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616 (United States)

    2009-11-15

    We present an accurate and efficient technique for calculating thermal X-ray absorption fine structure (XAFS) Debye-Waller factors (DWFs) applicable to crystalline materials. Using Density Functional Theory on a 3x3x3 supercell pattern of MnO structure, under the nonlocal hybrid B3LYP functional paired with Gaussian local basis sets, we obtain the normal mode eigenfrequencies and eigenvectors; these parameters are in turn used to calculate single and multiple scattering XAFS DWFs. The DWFs obtained via this technique are temperature dependent expressions and can be used to substantially reduce the number of fitting parameters, when experimental spectra are fitted with a hypothetical structure. The size of the supercell size limits the R-space range that these parameters could be used. Therefore corresponding DWFs for paths outside of this range are calculated using the correlated Debye model. Our method is compared with prior cluster calculations and with corresponding values obtained from fitting experimental XAFS spectra on manganosite with simulated spectra.

  15. Insights into the crystal chemistry of Earth materials rendered by electron density distributions: Pauling's rules revisited

    Energy Technology Data Exchange (ETDEWEB)

    Gibbs, Gerald V.; Ross, Nancy L.; Cox, David F.; Rosso, Kevin M.

    2014-05-20

    coordination number of the atom is determined uniquely independent of the asphericity and sizes of the atom. A power law connection established between the bond lengths and bond strengths for crystals and molecules is mirrored by a comparable power law connection between bond length and the accumulation of the electron density between bonded pairs of atoms, a connection that is consistent with Pauling's electroneutrality postulate that the charges of the atoms in an oxide are negligibly small. The connection indicates that a one-to-one correspondence exists between the accumulation between a pair of bonded atoms and the Pauling bond strength for M-O bonded interaction for all atoms of the periodic table. The connection provides a common basis for understanding the success of the manifold applications that have been made with the bond valence theory model together with the modeling of crystal structures, chemical zoning, leaching and cation transport in batteries and the like. We believe that the wide spread applications of the model in mineralogy and material science owes much of its success to the direct connection between bond strength and the quantum mechanical observable, the electron density distribution. Comparable power law expressions established for the bonded interactions for both crystals and molecules support Pauling's assertion that his second rule has significance for molecules as well as for crystals. A simple expression is found that provides a one to one connection between the accumulation of the electron density between bonded M and O atoms and the Pauling bond strength for all M atoms of the periodic table with ~ 95 % of the variation of the bond strength being explained in terms of a linear dependence on the accumulated electron density. Compelling evidence is presented that supports the argument that the Si-O bonded interactions for tiny siloxane molecules and silicate crystals are chemically equivalent.

  16. A density functional theory study on the thermodynamic and dynamic properties of anthraquinone analogue cathode materials for rechargeable lithium ion batteries.

    Science.gov (United States)

    Yang, Shu-Jing; Qin, Xiao-Ya; He, Rongxing; Shen, Wei; Li, Ming; Zhao, Liu-Bin

    2017-05-21

    Organic redox compounds have become the emerging electrode materials for rechargeable lithium ion batteries. The high electrochemical performance provides organic electrode materials with great opportunities to be applied in electric energy storage devices. Among the different types of organic materials, conjugated carbonyl compounds are the most promising type at present, because only they can simultaneously achieve, high energy density, high cycling stability, and high power density. In this research, a series of heteroatom substituted anthraquinone (AQ) derivatives were designed theoretically so that the high theoretical capacity of AQ remained. The discharge and charge mechanism as well as the thermodynamic and dynamic properties of AQ and its derivatives were investigated using first-principles density functional theory. Using heteroatom substitution, both the thermodynamic and dynamic properties of AQ as cathode materials could be largely improved. Among these conjugated carboxyl compounds, BDOZD and BDIOZD with a simultaneously high theoretical capacity and high working potential exhibit the largest energy density of about 780 W h kg(-1), which is 41% larger than that of AQ. The PQD with the smallest value of λ gives the largest charge transfer rate constant, which is about four times as large as the prototype molecule, AQ. The most interesting finding is that the lithium ion transfer plays a very important role in influencing both the discharge potential and electrochemical charge transfer rate. The present study illustrates that theoretical calculations provide a highly effective way to discover potential materials for use with rechargeable lithium ion batteries.

  17. Isomerization Pathways of ONCNO: Unstable or Metastable?

    Science.gov (United States)

    He, Fei-Fei; Gao, Si-Meng; Petris, Giulia de; Rosi, Marzio; Ding, Yi-Hong

    2016-07-14

    Fulminates containing the CNO(-) ion have been widely utilized as high-energy density materials (HEDMs) for more than 120 years. Yet no purely covalently bound CNO molecule, i.e., nitrile oxide, is known to behave as an HEDM. In this study, we performed a thorough investigation of the potential energy surface of nitrile oxide ONCNO and related isomers, applying various sophisticated methods including G4, CBS-QB3, W1BD, CCSD(T)/CBS, and CASPT2/CBS. The Gibbs free energy calculations showed that the decomposition of ONCNO to the considerably endothermic products CNO + NO is favored compared to that into the highly exothermic products CO2 + N2. Thus, ONCNO fails to be the long expected nitrile oxide HEDM. However, with the rate-determining barrier of 23.3 kcal mol(-1) at the W1BD level, ONCNO should be experimentally accessible.

  18. Optimization of sintering conditions in bulk MgB{sub 2} material for improvement of critical current density

    Energy Technology Data Exchange (ETDEWEB)

    Muralidhar, M., E-mail: miryala1@shibaura-it.ac.jp [Superconducting Materials Laboratory, Department of Materials Science and Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Nozaki, K.; Kobayashi, H. [Superconducting Materials Laboratory, Department of Materials Science and Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan); Zeng, X.L.; Koblischka-Veneva, A.; Koblischka, M.R. [Experimental Physics, Saarland University, P.O. Box 151150, 66041 Saarbrücken (Germany); Inoue, K.; Murakami, M. [Superconducting Materials Laboratory, Department of Materials Science and Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Koto-ku, Tokyo 135-8548 (Japan)

    2015-11-15

    The present investigation focuses on methods to further improve the J{sub c} values of disk-shaped bulk MgB{sub 2} superconductors by optimizing the sintering conditions. We prepared two sets of bulk MgB{sub 2} material from commercial high-purity powders of Mg metal and amorphous B using a single-step solid-state reaction process. To optimize the sintering time, a set of samples was sintered at 775 °C with sintering duration ranging between 1 and 10 h (pure Ar atmosphere). A second set of samples was produced similarly at 775, 780, 785, 795, 800 and 805 °C (3 h, pure argon atmosphere). X-ray diffraction analysis showed that both sets of samples were single phase MgB{sub 2}. Magnetization measurements confirmed a sharp superconducting transition with T{sub c,onset} ≈ 38.2 K–38.8 K. The critical current density (J{sub c}) values for MgB{sub 2} samples produced for 1 h were the highest in all processed materials, i.e., the high J{sub c} value of 270,000 A/cm{sup 2} and 125,000 A/cm{sup 2} (20 K, self-field and 1 T) were achieved in the sample produced at 775 °C, without any additional doping. In contrast, the second series of samples clearly indicated that at 805 °C (3 h) the highest J{sub c} of 245,000 A/cm{sup 2} and 110,000 A/cm{sup 2} (20 K, self-field and 1 T) were achieved. AFM and EBSD observations indicated that largest amount of fine grains do exist in the sample sintered at 775 °C, but the narrowest distribution of grains does exist in the sample sintered at 800 °C. The present results clearly demonstrate a strong relation between the microstructure and the pinning performance. The optimization of the sintering conditions is crucial to improve the performance of bulk MgB{sub 2} samples. - Highlights: • We had successfully improved the performance of sintered, pure bulk MgB{sub 2} materials. • EBSD observations clarified that the grain sizes are in the 100–500 nm range. • The high J{sub c} value at 20 K, 0 T and 1 T are 2.70 × 10{sup 5} A

  19. Calibrating Reaction Enthalpies: Use of Density Functional Theory and the Correlation Consistent Composite Approach in the Design of Photochromic Materials.

    Science.gov (United States)

    Letterman, Roger G; DeYonker, Nathan J; Burkey, Theodore J; Webster, Charles Edwin

    2016-12-22

    Acquisition of highly accurate energetic data for chromium-containing molecules and various chromium carbonyl complexes is a major step toward calibrating bond energies and thermal isomerization energies from mechanisms for Cr-centered photochromic materials being developed in our laboratories. The performance of six density functionals in conjunction with seven basis sets, utilizing Gaussian-type orbitals, has been evaluated for the calculation of gas-phase enthalpies of formation and enthalpies of reaction at 298.15 K on various chromium-containing systems. Nineteen molecules were examined: Cr(CO)6, Cr(CO)5, Cr(CO)5(C2H4), Cr(CO)5(C2ClH3), Cr(CO)5(cis-(C2Cl2H2)), Cr(CO)5(gem-(C2Cl2H2)), Cr(CO)5(trans-(C2Cl2H2)), Cr(CO)5(C2Cl3H), Cr(CO)5(C2Cl4), CrO2, CrF2, CrCl2, CrCl4, CrBr2, CrBr4, CrOCl2, CrO2Cl2, CrOF2, and CrO2F2. The performance of 69 density functionals in conjunction with a single basis set utilizing Slater-type orbitals (STO) and a zeroth-order relativistic approximation was also evaluated for the same test set. Values derived from density functional theory were compared to experimental values where available, or values derived from the correlation consistent composite approach (ccCA). When all reactions were considered, the functionals that exhibited the smallest mean absolute deviations (MADs, in kcal mol(-1)) from ccCA-derived values were B97-1 (6.9), VS98 (9.0), and KCIS (9.4) in conjunction with quadruple-ζ STO basis sets and B97-1 (9.3) in conjunction with cc-pVTZ basis sets. When considering only the set of gas-phase reaction enthalpies (ΔrH°gas), the functional that exhibited the smallest MADs from ccCA-derived values were B97-1 in conjunction with cc-pVTZ basis sets (9.1) and PBEPBE in conjunction with polarized valence triple-ζ basis set/effective core potential combination for Cr and augmented and multiple polarized triple-ζ Pople style basis sets (9.5). Also of interest, certainly because of known cancellation of errors, PBEPBE with the

  20. On the effective atomic number and electron density: A comprehensive set of formulas for all types of materials and energies above 1 keV

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Thind, K.S.;

    2008-01-01

    A comprehensive and consistent set of formulas is given for calculating the effective atomic number and electron density for all types of materials and for all photon energies greater than 1 keV. The are derived from first principles using photon interaction cross sections of the constituent atoms...

  1. Monte carlo simulation of innovative neutron and photon shielding material composing of high density concrete, waste rubber, lead and boron carbide

    Science.gov (United States)

    Aim-O, P.; Wongsawaeng, D.; Phruksarojanakun, P.; Tancharakorn, S.

    2017-06-01

    High-density concrete exhibits high strength and can perform an important role of gamma ray attenuation. In order to upgrade this material’s radiation-shielding performance, hydrogen-rich material can be incorporated. Waste rubber from vehicles has high hydrogen content which is the prominent characteristic to attenuate neutron. The objective of this work was to evaluate the radiation-shielding properties of this composite material against neutron and photon radiations. Monte Carlo transport simulation was conducted to simulate radiation through the composite material. Am-241/Be was utilized for neutron source and Co-60 for photon source. Parameters of the study included volume percentages of waste rubber, lead and boron carbide and thickness of the shielding material. These designs were also fabricated and the radiation shielding properties were experimentally evaluated. The best neutron and gamma ray shielding material was determined to be high-density concrete mixed with 5 vol% crumb rubber and 5 vol% lead powder. This shielding material increased the neutron attenuation by 64% and photon attenuation by 68% compared to ordinary concrete. Also, increasing the waste rubber content to greater than 5% resulted in a decrease in the radiation attenuation. This innovative composite radiation shielding material not only benefits nuclear science and engineering applications, but also helps solve the environmental issue of waste rubber.

  2. Examples of density, orientation and shape optimal design for stiffness and/or strength with orthotropic materials

    DEFF Research Database (Denmark)

    Pedersen, Pauli

    2004-01-01

    a penalization approach to obtain "black and white" designs, i.e. uniform material or holes, is often applied in optimal design. A specific example is studied to show the effect of the penalization, but is restricted here to an isotropic material. When the total amount of material is not specified, a conflict...

  3. Integration of high capacity materials into interdigitated mesostructured electrodes for high energy and high power density primary microbatteries

    Science.gov (United States)

    Pikul, James H.; Liu, Jinyun; Braun, Paul V.; King, William P.

    2016-05-01

    Microbatteries are increasingly important for powering electronic systems, however, the volumetric energy density of microbatteries lags behind that of conventional format batteries. This paper reports a primary microbattery with energy density 45.5 μWh cm-2 μm-1 and peak power 5300 μW cm-2 μm-1, enabled by the integration of large volume fractions of high capacity anode and cathode chemistry into porous micro-architectures. The interdigitated battery electrodes consist of a lithium metal anode and a mesoporous manganese oxide cathode. The key enabler of the high energy and power density is the integration of the high capacity manganese oxide conversion chemistry into a mesostructured high power interdigitated bicontinuous cathode architecture and an electrodeposited dense lithium metal anode. The resultant energy density is greater than previously reported three-dimensional microbatteries and is comparable to commercial conventional format lithium-based batteries.

  4. Structure factor of blends of solvent-free nanoparticle–organic hybrid materials: density-functional theory and small angle X-ray scattering

    KAUST Repository

    Yu, Hsiu-Yu

    2014-09-15

    © the Partner Organisations 2014. We investigate the static structure factor S(q) of solvent-free nanoparticle-organic hybrid materials consisting of silica nanocores and space-filling polyethylene glycol coronas using a density-functional theory and small angle X-ray scattering measurements. The theory considers a bidisperse suspension of hard spheres with different radii and tethered bead-spring oligomers with different grafting densities to approximate the polydispersity effects in experiments. The experimental systems studied include pure samples with different silica core volume fractions and the associated mean corona grafting densities, and blends with different mixing ratios of the pure samples, in order to introduce varying polydispersity of corona grafting density. Our scattering experiments and theory show that, compared to the hard-sphere suspension with the same core volume fraction, S(q) for pure samples exhibit both substantially smaller values at small q and stronger particle correlations corresponding to a larger effective hard core at large q, indicating that the tethered incompressible oligomers enforce a more uniform particle distribution, and the densely grafted brush gives rise to an additional exclusionary effect between the nanoparticles. According to the theory, polydispersity in the oligomer grafting density controls the deviation of S(q) from the monodisperse system at smaller q, and the interplay of the enhanced effective core size and the entropic attraction among the particles is responsible for complex variations in the particle correlations at larger q. The successful comparison between the predictions and the measurements for the blends further suggests that S(q) can be used to assess the uniformity of grafting density in polymer-grafted nanoparticle materials. This journal is

  5. Dual-energy X-ray absorptiometry for the simultaneous determination of Density and Moisture Content in Porous Structural Materials

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Jensen, Signe Kamp; Gerward, Leif

    1999-01-01

    The paper describes the dual-energy x-ray equipment, which consists of a x-ray source, filters and a detector. The x-ray beam can be moved automatically in two dimensions relative to a fixed specimen. The purpose of the equipment is to measure simultaneously the density and moisture content...

  6. Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

    DEFF Research Database (Denmark)

    Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes

    2009-01-01

    We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...

  7. SYNCHROTRON-RADIATION X-RAY-DIFFRACTION OF MODULATED STRUCTURES IN CHARGE-DENSITY-WAVE MATERIALS - APPLICATION TO NBSE3

    NARCIS (Netherlands)

    VANSMAALEN, S; DEBOER, JL; COPPENS, P

    1993-01-01

    Synchrotron radiation X-ray diffraction has been performed on niobium triselenide at 20K. The modulation parameters belonging to both Charge-Density-Waves (CDW's) have been determined. The high-temperature CDW is found to comprise of displacements on all atoms of column III, as well as on Se atoms o

  8. Flammability of radiation cross-linked low density polyethylene as an insulating material for wire and cable

    Science.gov (United States)

    Basfar, A. A.

    2002-03-01

    Various formulations of low-density polyethylene blended with ethylene vinyl acetate were prepared to improve the flame retardancy for wire and cable applications. The prepared formulations were cross-linked by γ-rays to 50, 100, 150 and 200 kGy in the presence of trimethylolpropane triacrylate (TMPTA). The effect of thermal aging on mechanical properties of these formulations were investigated. In addition, the influence of various combinations of aluminum trihydroxide and zinc borate as flame retardant fillers on the flammability was explored. Limiting oxygen index (LOI) and average extent of burning were used to characterize the flammability of investigated formulations. An improved flame retardancy of low density polyethylene was achieved by various combinations of flame ratardant fillers and cross-linking by gamma radiation.

  9. Surface layer structure and average contact temperature of copper-containing materials under dry sliding with high electric current density

    Science.gov (United States)

    Fadin, V. V.; Aleutdinova, M. I.; Rubtsov, V. Ye.; Aleutdinov, K. A.

    2016-11-01

    Dry sliding of copper and powder composites of Cu-Fe and Cu-Fe-graphite compositions against 1045 steel under electric current of contact density higher than 250 A/cm2 has been studied, which demonstrated the change in surface layer structure and formation of tribolayer consisting of iron, copper and FeO oxide. Signs of quasi-viscous flow of worn surface were observed. It was noted that the thin contact layer containing about 40 at % of oxygen and 40% of Fe was the main factor decreasing the adhesion interaction. It was affirmed that the introduction of graphite into the primary structure of the composite leads to rather low content of FeO oxide and to the increased tendency of surface layer to catastrophic deterioration under sliding with contact current density of about 300 A/cm2. The temperature of contact did not exceed 400°C.

  10. Electronic and atomic structures of the Sr3Ir4Sn13 single crystal: A possible charge density wave material

    Science.gov (United States)

    Wang, H.-T.; Srivastava, M. K.; Wu, C.-C.; Hsieh, S.-H.; Wang, Y.-F.; Shao, Y.-C.; Liang, Y.-H.; Du, C.-H.; Chiou, J.-W.; Cheng, C.-M.; Chen, J.-L.; Pao, C.-W.; Lee, J.-F.; Kuo, C. N.; Lue, C. S.; Wu, M.-K.; Pong, W.-F.

    2017-01-01

    X-ray scattering (XRS), x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopic techniques were used to study the electronic and atomic structures of the high-quality Sr3Ir4Sn13 (SIS) single crystal below and above the transition temperature (T* ≈ 147 K). The evolution of a series of modulated satellite peaks below the transition temperature in the XRS experiment indicated the formation of a possible charge density wave (CDW) in the (110) plane. The EXAFS phase derivative analysis supports the CDW-like formation by revealing different bond distances [Sn1(2)-Sn2] below and above T* in the (110) plane. XANES spectra at the Ir L3-edge and Sn K-edge demonstrated an increase (decrease) in the unoccupied (occupied) density of Ir 5d-derived states and a nearly constant density of Sn 5p-derived states at temperatures T atomic structures and the CDW-like phase in the SIS single crystal. PMID:28106144

  11. 复合材料飞轮结构与储能密度%COMPOSITE MATERIAL FLYWHEEL STRUCTURE AND ENERGY-S TORING DENSITY

    Institute of Scientific and Technical Information of China (English)

    李文超; 沈祖培

    2001-01-01

    为提高飞轮的储能密度,需采用合适的转子材料和合理的转子结构。复合材料与各向同性材料相比具有明显优势。多层转子结构突破了单层转子内外半径比的限制,可明显改善转子内部的应力分布,提高飞轮的储能密度。该文论述了复合材料飞轮储能密度的影响因素,对复合材料转子的应力分布作了定量分析,比较了单层和多层转子的特点,综合考虑飞轮设计的各种因素,提出了飞轮转子结构参数的设计方法。%In order to increase energy-storin g density offlywheel,appropriate rotor material and reasonable structure should be used.Co mpared with isotropic materials,the composite material has evident advantages.M u lti-ring rotor structure breaks through restriction of the ratio of inner radii to outer radii,which can evidently improve the distribution of rotor stress and incre ase flywheel energy-storing density.This paper discusses the influence factor i n the energy-storing density of composite flywheel,quantificationally analyzes the stress distribution of composite material rotor,and compared the characteris tics of single-ring with multi-ring rotor.Synthetically considering all these factors,the design method of flywheel rotor structure parameters was put forward

  12. An analysis of the impact of native oxide, surface contamination and material density on total electron yield in the absence of surface charging effects

    Science.gov (United States)

    Iida, Susumu; Ohya, Kaoru; Hirano, Ryoichi; Watanabe, Hidehiro

    2016-10-01

    The effects of the presence of a native oxide film or surface contamination as well as variations in material density on the total electron yield (TEY) of Ru and B4C were assessed in the absence of any surface charging effect. The experimental results were analyzed using semi-empirical Monte Carlo simulations and demonstrated that a native oxide film increased the TEY, and that this effect varied with film thickness. These phenomena were explained based on the effect of the backscattered electrons (BSEs) at the interface between Ru and RuO2, as well as the lower potential barrier of RuO2. Deviations in the material density from the theoretical values were attributed to the film deposition procedure based on fitting simulated TEY curves to experimental results. In the case of B4C, the TEY was enhanced by the presence of a 0.8-nm-thick surface contamination film consisting of oxygenated hydrocarbons. The effect of the low potential barrier of the contamination film was found to be significant, as the density of the B4C was much lower than that of the Ru. Comparing the simulation parameters generated in the present work with Joy's database, it was found that the model and the input parameters used in the simulations were sufficiently accurate.

  13. Local states in one-dimensional CDW (charge density wave) materials: Spectral signatures for polarons and bipolarons in MX chains

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, B. I.; Donohoe, R. J.; Worl, L. A.; Bulou, A. D.F.; Arrington, C. A.; Gammel, J. T.; Saxena, A.; Bishop, A. R.

    1990-01-01

    We have undertaken a combined theoretical and experimental effort directed toward the examination of both the ground and defect states in halide-bridged mixed-valence metal linear chains materials as they are tuned within and between broken symmetry phases. Novel low-dimensional highly correlated electronic materials offer a difficult theoretical challenge as we must span from a description of electronic structure on a molecular scale to the meso scale structure that is intrinsic to these solids. Our theoretical effort at Los Alamos combines quantum chemistry, band structure calculations, and many body modeling using Peierls-Hubbard Hamiltonians in order to model ground and local states. The experimental effort combines synthesis and a variety of microscopic structural and spectroscopic probes and macroscopic measurements in an effort to fully characterize both ground and local states as these materials are tuned in the phase boundary regions between broken symmetry states. The present article summarizes some of our recent research using optical spectroscopy to obtain signatures of photoexcited and intrinsic local states and compares these experimental results with Peierls-Hubbard calculations of the optical properties of these materials. Details concerning the theoretical and experimental approaches can be found elsewhere.

  14. Development and characterization of high temperature, high energy density dielectric materials to establish routes towards power electronics capacitive devices

    Science.gov (United States)

    Shay, Dennis P.

    The maximum electrostatic energy density of a capacitor is a function of the relative permittivity (epsilonr) and the square of the dielectric breakdown strength (Eb). Currently, state-of-the art high temperature (>200 °C), SiC-based power electronics utilize CaZrO3-rich NP0/C0G-type capacitors, which have low relative permittivities of epsilonr ˜ 30-40, high breakdown strengths (> 1.0 MV/cm), and are chosen for their minimal change in energy storage with temperature. However, with operating temperatures exceeding the rated temperatures for such capacitors, there is an opportunity to develop new dielectric ceramics having higher energy densities and volumetric efficiencies at high temperatures (>200 °C) by utilizing higher permittivity dielectrics while maintaining high breakdown strengths via doping. The solid solution behavior of was characterized in order to determine the optimal composition for balancing permittivity and dielectric breakdown strength to obtain high energy densities at elevated temperatures. Characterization by X-ray diffraction (XRD) showed Vegard's law behavior across the solid solution with minimal 2nd phases. To determine a Ca(TixZr1-x)O3 composition that will also minimize electronic or band conduction, the optical properties of the Ca(TixZr1-x)O3 solid solution were investigated to identify a composition on the CaTiO3 - rich end of the solid solution with a large band gap. Both ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis) and spectroscopic ellipsometry were utilized to determine the Ca(TixZr1-x)O3 band gaps and optical properties. The resistivity at 250 °C scaled with the band gap energy across the solid solution. Comparing the current-voltage (I--V) behavior at 250 °C for Ca(Tix-yMnyZr0.2)O3 (CTZ + Mn) where x = 0.7, 0.8, 0.9, and y = 0.005, it was found that the Ca(Ti 0.795Mn0.005Zr0.2)O3 composition showed the lowest current density and a decrease in current density of 5 orders of magnitude compared to the un

  15. Density functional description of adsorption in slitlike pores modified with chain molecules: a simple model for pillaredlike materials.

    Science.gov (United States)

    Matusewicz, M; Patrykiejew, A; Sokołowski, S; Pizio, O

    2007-11-07

    We propose a density functional theory to describe adsorption of Lennard-Jones fluid in slitlike pores modified by chain molecules. Specifically, the chains are bonded by their ends to the opposite pore walls, so they can form pillaredlike structure. Two models are studied. In the first model, the nonterminating segments of chains can change their configuration inside the pore upon adsorption of spherical species. In the second model, the chains configuration remains fixed, so that the system is similar to a nonuniform quenched-annealed mixture. We study capillary condensation of fluid species inside such modified pores and compare the results obtained for two models.

  16. Effective atomic numbers and electron densities of some human tissues and dosimetric materials for mean energies of various radiation sources relevant to radiotherapy and medical applications

    Science.gov (United States)

    Kurudirek, Murat

    2014-09-01

    Effective atomic numbers, Zeff, and electron densities, neff, are convenient parameters used to characterise the radiation response of a multi-element material in many technical and medical applications. Accurate values of these physical parameters provide essential data in medical physics. In the present study, the effective atomic numbers and electron densities have been calculated for some human tissues and dosimetric materials such as Adipose Tissue (ICRU-44), Bone Cortical (ICRU-44), Brain Grey/White Matter (ICRU-44), Breast Tissue (ICRU-44), Lung Tissue (ICRU-44), Soft Tissue (ICRU-44), LiF TLD-100H, TLD-100, Water, Borosilicate Glass, PAG (Gel Dosimeter), Fricke (Gel Dosimeter) and OSL (Aluminium Oxide) using mean photon energies, Em, of various radiation sources. The used radiation sources are Pd-103, Tc-99, Ra-226, I-131, Ir-192, Co-60, 30 kVp, 40 kVp, 50 kVp (Intrabeam, Carl Zeiss Meditec) and 6 MV (Mohan-6 MV) sources. The Em values were then used to calculate Zeff and neff of the tissues and dosimetric materials for various radiation sources. Different calculation methods for Zeff such as the direct method, the interpolation method and Auto-Zeff computer program were used and agreements and disagreements between the used methods have been presented and discussed. It has been observed that at higher Em values agreement is quite satisfactory (Dif.<5%) between the adopted methods.

  17. Dynamic impact response of high-density square honeycombs made of TRIP steel and TRIP matrix composite material

    Directory of Open Access Journals (Sweden)

    Weigelt C.

    2012-08-01

    Full Text Available Two designs of square-celled metallic honeycomb structures fabricated by a modified extrusion technology based on a powder feedstock were investigated. The strength and ductility of these cellular materials are achieved by an austenitic CrNi (AISI 304 steel matrix particle reinforced by an MgO partially-stabilized zirconia building up their cell wall microstructure. Similar to the mechanical behaviour of the bulk materials, the strengthening mechanism and the martensitic phase transformations in the cell walls are affected by the deformation temperature and the nominal strain rate. The microstructure evolution during quasi-static and dynamic impact compression up to high strain rates of 103 1/s influences the buckling and failure behaviour of the honeycomb structures. In contrast to bending-dominated quasi-isotropic networks like open-celled metal foams, axial compressive loading to the honeycomb’s channels causes membrane stretching as well as crushing of the vertical cell node elements and cell walls. The presented honeycomb materials differ geometrically in their cell wall thickness-to-cell size-ratio. Therefore, the failure behaviour is predominantly controlled by global buckling and torsional-flexural buckling, respectively, accompanied by plastic matrix flow and strengthening of the cell wall microstructure.

  18. Large-scale atomistic simulations of nanostructured materials based on divide-and-conquer density functional theory

    Directory of Open Access Journals (Sweden)

    Vashishta P.

    2011-05-01

    Full Text Available A linear-scaling algorithm based on a divide-and-conquer (DC scheme is designed to perform large-scale molecular-dynamics simulations, in which interatomic forces are computed quantum mechanically in the framework of the density functional theory (DFT. This scheme is applied to the thermite reaction at an Al/Fe2O3 interface. It is found that mass diffusion and reaction rate at the interface are enhanced by a concerted metal-oxygen flip mechanism. Preliminary simulations are carried out for an aluminum particle in water based on the conventional DFT, as a target system for large-scale DC-DFT simulations. A pair of Lewis acid and base sites on the aluminum surface preferentially catalyzes hydrogen production in a low activation-barrier mechanism found in the simulations

  19. Optimal III-nitride HEMTs: from materials and device design to compact model of the 2DEG charge density

    Science.gov (United States)

    Li, Kexin; Rakheja, Shaloo

    2017-02-01

    In this paper, we develop a physically motivated compact model of the charge-voltage (Q-V) characteristics in various III-nitride high-electron mobility transistors (HEMTs) operating under highly non-equilibrium transport conditions, i.e. high drain-source current. By solving the coupled Schrödinger-Poisson equation and incorporating the two-dimensional electrostatics in the channel, we obtain the charge at the top-of-the-barrier for various applied terminal voltages. The Q-V model accounts for cutting off of the negative momenta states from the drain terminal under high drain-source bias and when the transmission in the channel is quasi-ballistic. We specifically focus on AlGaN and AlInN as barrier materials and InGaN and GaN as the channel material in the heterostructure. The Q-V model is verified and calibrated against numerical results using the commercial TCAD simulator Sentaurus from Synopsys for a 20-nm channel length III-nitride HEMT. With 10 fitting parameters, most of which have a physical origin and can easily be obtained from numerical or experimental calibration, the compact Q-V model allows us to study the limits and opportunities of III-nitride technology. We also identify optimal material and geometrical parameters of the device that maximize the carrier concentration in the HEMT channel in order to achieve superior RF performance. Additionally, the compact charge model can be easily integrated in a hierarchical circuit simulator, such as Keysight ADS and CADENCE, to facilitate circuit design and optimization of various technology parameters.

  20. Spectral properties of actinide materials: Charge density self-consistent LDA+Hubbard I method in FP-LAPW basis

    Energy Technology Data Exchange (ETDEWEB)

    Kolorenc, Jindrich [Institute of Physics ASCR, Prague (Czech Republic); University of Hamburg, Hamburg (Germany); Shick, Alexander B. [Institute of Physics ASCR, Prague (Czech Republic); Havela, Ladislav [Charles University, Prague (Czech Republic); Lichtenstein, Alexander I. [University of Hamburg, Hamburg (Germany)

    2010-07-01

    We provide a numerically efficient procedure to perform LDA+Hubbard I calculations including self-consistency over the charge density in the FP-LAPW basis. The method is applied to Pu, Am, and PuAm and PuCe alloys. Our results for valence photoemission spectra (PES) agree with experimental data and with previous LDA+DMFT calculations. Analysis of the J=5/2 and J=7/2 contributions to the f-occupation supports the intermediate-coupling picture of f-states in heavy actinides. The electronic specific heat coefficient is calculated for PuAm and PuCe alloys in reasonable agreement with recent experiments. We show that Pu atoms keep their mixed-valence character in these alloys. Next, we study electronic and spectral properties of Pu-based superconductor PuCoGa{sub 5} and obtain good agreement with experimental PES. Finally, we analyze surface effects. In Pu monolayer, we find substantial modification of PES due to 5f-electron localization consistent with experimental observations.

  1. Development of a low-adiabat drive for material science experiments on NIF using release and recompression of low density organic foams

    Science.gov (United States)

    Wehrenberg, Christopher; Prisbrey, Shon T.; Park, Hye-Sook; Benedetti, L. Robin; Huntington, Channing; McNaney, James; Smith, Ray; Panas, Cynthia; Cook, Angela; Remington, Bruce; Arsenlis, Tom; Graham, Peter

    2015-11-01

    A series of experiments were performed on NIF to develop a planar, 3-shock, low-adiabat drive for material science experiments. Physics samples (Ta, Pb, etc.) are loaded to 3-4 Mbar while staying well below the melt temperature. X-ray ablation from an indirect drive launches a strong (~ 50 Mbar), decaying shock through a precision fabricated ``reservoir,'' consisting of a CH ablator, followed by layers of Al, CH(18.75%I), ~ 375 mg/cc carbonized resorcinol formaldehyde foam, and a final layer of low density (10-35) mg/cc foam. As the releasing reservoir stagnates on a Ta drive plate, VISAR is used to measures the resulting compression waves. The lowest density reservoir layer is responsible for the leading shock and induces the most entropy during the drive. LLNL has developed a new, low-density foam called JX6 (C20H30) for the purpose of controlling the leading shock. We will describe a series of experiments done on NIF to test the combined release and recompression properties of JX6 and to develop a new, lower-adiabat drive. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  2. [Regeneration processes in bone defects after implantation of composite material of different density of polylactide origin filled with HAP (experimental-morphological study)].

    Science.gov (United States)

    Kulakov, A A; Grigor'ian, A S; Krotova, L I; Popov, V K; Volozhin, A I; Losev, V F

    2009-01-01

    In experimental-morphological study on 6 dogs the dynamics of regenerate formation in ulna and mandible defects after implantation in them composite material of different density (0.46-0.50 and 0.38-0.42 g/cm(3)) of polylactide (PL) origin filled with HAP was followed at the terms of 6 and 9 months. Histologic study and structural determinant distribution analysis in the content of regenerate showed that optimal results according to the bone defect substitution by bone regenerate criterion at 9th month of the experiment were received after composite material from PL and HAP with the density of 0.38-0.42 g/cm(3) implantation. Newly formed trabecular bone tissue was seen in the regenerate and as well as strong tendency for bone matrix maturation. It was confirmed by the appearance of lamellar structures in newly formed bone trabecules situated in peripheral zones of bone defect. In bone mandible defects the substitution process of the implants from PL with HAP by the bone tissue was much slower than in ulna defects.

  3. Beam hardening and smoothing correction effects on performance of micro-ct SkyScan 1173 for imaging low contrast density materials

    Energy Technology Data Exchange (ETDEWEB)

    Sriwayu, Wa Ode [Physics Departement, Haluoleo University Indonesia (Indonesia); Haryanto, Freddy; Khotimah, Siti Nurul; Latief, Fourier Dzar Eljabbar [Physics Departement, ITB Indonesia email : ayoe-fisika@yahoo.com (Indonesia)

    2015-04-16

    We have designed and fabricated phantom mimicking breast cancer composition known as a region that has low contrast density. The used compositions are a microcalcifications, fatty tissues and tumor mass by using Al{sub 2}O{sub 3}, C{sub 27}H{sub 46}O, and hard nylon materials. Besides, phantom also has a part to calculate low cost criteria /CNR (Contrast to Noise Ratio). Uniformity will be measured at water distillation medium located in a part of phantom scale contrast. Phantom will be imaged by using micro ct-sky scan 1173 high energy type, and then also can be quantified CT number to examine SkyScan 1173 performance in imaging low contrast density materials. Evaluation of CT number is done at technique configuration parameter using voltage of 30 kV, exposure 0.160 mAs, and camera resolution 560x560 pixel, the effect of image quality to reconstruction process is evaluated by varying image processing parameters in the form of beam hardening corrections with amount of 25%, 66% and100% with each smoothing level S10,S2 and S7. To obtain the better high quality image, the adjustment of beam hardening correction should be 66% and smoothing level reach maximal value at level 10.

  4. A density functional study on properties of a Cu3Zn material and CO adsorption onto its surfaces

    Science.gov (United States)

    Tang, Qian-Lin; Duan, Xiao-Xuan; Liu, Bei; Wei, An-Qing; Liu, Sheng-Long; Wang, Qi; Liang, Yan-Ping; Ma, Xiao-Hua

    2016-02-01

    Prior experimental and theoretical efforts have provided strong evidence that the formation of α-brass such as Cu3Zn alloys in Cu/ZnO/Al2O3 CO2/CO hydrogenation catalysts enhances dramatically the catalytic activity toward methanol synthesis. In this work, a density functional theory (DFT) slab model has been adopted to get information concerning the bulk and surface properties of DO23-like Cu3Zn and to explore CO molecular adsorption, which will help pave the way to future rationalization of the impact of surface alloying on Cu/ZnO-based catalysis for CO2 and CO hydrogenations. Our calculations imply that the bulk modulus and cohesive energy of the binary solid solution lie between the corresponding ones for the individual components, but only the former quantity equals its composition weighted average. From the DFT-computed surface energies, the stability of Cu3Zn surfaces was predicted to be reinforced in the sequence (1 1 0) electronic structure evaluation reveals that as far as all the alloy surfaces under scrutiny are concerned, a layer of CO brought a decrease, not an increase, in work function for (1 0 1)Zn and (1 1 0)CuZn, though the electrons always flowed from the substrate to the adsorbate. The finding is not trivial at all since it counters the classical rule that an electronegative species raises the work function of the underlying surface. The bonding of CO to the Cu3Zn systems via C-Cu contacts was identified as being primarily covalent rather than ionic. A simple d-band energy model is able to capture the bonding tendency observed.

  5. Density functional theory meta-GGA + U study of water incorporation in the metal-organic framework material Cu-BTC

    Science.gov (United States)

    Cockayne, Eric; Nelson, Eric B.

    2015-07-01

    Water absorption in the metal-organic framework (MOF) material Cu-BTC, up to a concentration of 3.5 H2O per Cu ion, is studied via density functional theory at the meta-GGA + U level. The stable arrangements of water molecules show chains of hydrogen-bonded water molecules and a tendency to form closed cages at high concentration. Water clusters are stabilized primarily by a combination of water-water hydrogen bonding and Cu-water oxygen interactions. Stability is further enhanced by van der Waals interactions, electric field enhancement of water-water bonding, and hydrogen bonding of water to framework oxygens. We hypothesize that the tendency to form such stable clusters explains the particularly strong affinity of water to Cu-BTC and related MOFs with exposed metal sites.

  6. Materials

    Science.gov (United States)

    Glaessgen, Edward H.; Schoeppner, Gregory A.

    2006-01-01

    NASA Langley Research Center has successfully developed an electron beam freeform fabrication (EBF3) process, a rapid metal deposition process that works efficiently with a variety of weldable alloys. The EBF3 process can be used to build a complex, unitized part in a layer-additive fashion, although the more immediate payoff is for use as a manufacturing process for adding details to components fabricated from simplified castings and forgings or plate products. The EBF3 process produces structural metallic parts with strengths comparable to that of wrought product forms and has been demonstrated on aluminum, titanium, and nickel-based alloys to date. The EBF3 process introduces metal wire feedstock into a molten pool that is created and sustained using a focused electron beam in a vacuum environment. Operation in a vacuum ensures a clean process environment and eliminates the need for a consumable shield gas. Advanced metal manufacturing methods such as EBF3 are being explored for fabrication and repair of aerospace structures, offering potential for improvements in cost, weight, and performance to enhance mission success for aircraft, launch vehicles, and spacecraft. Near-term applications of the EBF3 process are most likely to be implemented for cost reduction and lead time reduction through addition of details onto simplified preforms (casting or forging). This is particularly attractive for components with protruding details that would require a significantly large volume of material to be machined away from an oversized forging, offering significant reductions to the buy-to-fly ratio. Future far-term applications promise improved structural efficiency through reduced weight and improved performance by exploiting the layer-additive nature of the EBF3 process to fabricate tailored unitized structures with functionally graded microstructures and compositions.

  7. Three-dimensional assessment of the effects of high-density embolization material on the absorbed dose in the target for Gamma Knife radiosurgery of arteriovenous malformations.

    Science.gov (United States)

    Watanabe, Yoichi; Sandhu, Divyajot; Warmington, Leighton; Moen, Sean; Tummala, Ramachandra

    2016-12-01

    OBJECTIVE Arteriovenous malformation (AVM) is an intracranial vascular disorder. Gamma Knife radiosurgery (GKRS) is used in conjunction with intraarterial embolization to eradicate the nidus of AVMs. Clinical results indicate that patients with prior embolization tend to gain less benefit from GKRS. The authors hypothesized that this was partly caused by dosimetric deficiency. The actual dose delivered to the target may be smaller than the intended dose because of increased photon attenuation by high-density embolic materials. The authors performed a phantom-based study to quantitatively evaluate the 3D dosimetric effect of embolic material on GKRS. METHODS A 16-cm-diameter and 12-cm-long cylindrical phantom with a 16-cm-diameter hemispherical dome was printed by a 3D printer. The phantom was filled with radiologically tissue-equivalent polymer gel. To simulate AVM treatment with embolization, phantoms contained Onyx 18. The material was injected into an AVM model, which was suspended in the polymer gel. The phantom was attached to a Leksell frame by standard GK fixation method, using aluminum screws, for imaging. The phantom was scanned by a Phillips CT scanner with the standard axial-scanning protocol (120 kV and 1.5-mm slice thickness). CT-based treatment planning was performed with the GammaPlan treatment planning system (version 10.1.1). The plan was created to cover a fictitious AVM target volume near the embolization areas with eleven 8-mm shots and a prescription dose of 20 Gy to 50% isodose level. Dose distributions were computed using both tissue maximum ratio (TMR) 10 and convolution dose-calculation algorithms. These two 3D dose distributions were compared using an in-house program. Additionally, the same analysis method was applied to evaluate the dosimetric effects for 2 patients previously treated by GKRS. RESULTS The phantom-based analyses showed that the mean dose difference between TMR 10 and convolution doses of the AVM target was no larger than

  8. Standard test method for nondestructive assay of special nuclear material in low density scrap and waste by segmented passive gamma-Ray scanning

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the transmission-corrected nondestructive assay (NDA) of gamma-ray emitting special nuclear materials (SNMs), most commonly 235U, 239Pu, and 241Am, in low-density scrap or waste, packaged in cylindrical containers. The method can also be applied to NDA of other gamma-emitting nuclides including fission products. High-resolution gamma-ray spectroscopy is used to detect and measure the nuclides of interest and to measure and correct for gamma-ray attenuation in a series of horizontal segments (collimated gamma detector views) of the container. Corrections are also made for counting losses occasioned by signal processing limitations (1-3). 1.2 There are currently several systems in use or under development for determining the attenuation corrections for NDA of radioisotopic materials (4-8). A related technique, tomographic gamma-ray scanning (TGS), is not included in this test method (9, 10, 11). 1.2.1 This test method will cover two implementations of the Segmented Gamma Scanning ...

  9. Density functional theory study the effects of oxygen-containing functional groups on oxygen molecules and oxygen atoms adsorbed on carbonaceous materials.

    Science.gov (United States)

    Qi, Xuejun; Song, Wenwu; Shi, Jianwei

    2017-01-01

    Density functional theory was used to study the effects of different types of oxygen-containing functional groups on the adsorption of oxygen molecules and single active oxygen atoms on carbonaceous materials. During gasification or combustion reactions of carbonaceous materials, oxygen-containing functional groups such as hydroxyl(-OH), carbonyl(-CO), quinone(-O), and carboxyl(-COOH) are often present on the edge of graphite and can affect graphite's chemical properties. When oxygen-containing functional groups appear on a graphite surface, the oxygen molecules are strongly adsorbed onto the surface to form a four-member ring structure. At the same time, the O-O bond is greatly weakened and easily broken. The adsorption energy value indicates that the adsorption of oxygen molecules changes from physisorption to chemisorption for oxygen-containing functional groups on the edge of a graphite surface. In addition, our results indicate that the adsorption energy depends on the type of oxygen-containing functional group. When a single active oxygen atom is adsorbed on the bridge site of graphite, it gives rise to a stable epoxy structure. Epoxy can cause deformation of the graphite lattice due to the transition of graphite from sp2 to sp3 after the addition of an oxygen atom. For quinone group on the edge of graphite, oxygen atoms react with carbon atoms to form the precursor of CO2. Similarly, the single active oxygen atoms of carbonyl groups can interact with edge carbon atoms to form the precursor of CO2. The results show that oxygen-containing functional groups on graphite surfaces enhance the activity of graphite, which promotes adsorption on the graphite surface.

  10. Three new energetic complexes with N,N-bis(1H-tetrazole-5-yl)-amine as high energy density materials: syntheses, structures, characterization and effects on the thermal decomposition of RDX.

    Science.gov (United States)

    Yang, Qi; Song, Xiaxia; Zhang, Wendou; Hou, Lei; Gong, Qibing; Xie, Gang; Wei, Qing; Chen, Sanping; Gao, Shengli

    2017-02-21

    Three new energetic complexes, [Pb(bta)(H2O)]n (1), [PbCu(bta)2(H2O)5]·2H2O (2) and PbCu(bta)2 (3) (H2bta = N,N-bis(1H-tetrazole-5-yl)-amine), have been synthesized and characterised. In particular, 3 was readily synthesized by dehydration of 2 at 190 °C. Single crystal X-ray diffraction revealed that 1 has a 3D framework structure and 2 presents a 3D supermolecular architecture. Thermoanalyses demonstrated that the main frames of 1 and 2 have good thermostabilities up to 314 °C for 1 and 231 °C for 2. Non-isothermal kinetic and thermodynamic parameters of exothermic decomposition processes of 1 and 2 were obtained by Kissinger's and Ozawa's methods. Based on the constant-volume combustion energies measured by a precise rotating-bomb calorimeter, the standard molar enthalpies of formation of 1 and 2 were determined. The calculation of the detonation properties of 1 and 2 and the impact sensitivity tests of 1, 2 and 3 were carried out. In addition, 1, 2 and 3 were explored as combustion promoters to accelerate the thermal decompositions of RDX (1,3,5-trinitro-1,3,5-triazine) by differential scanning calorimetry. Experimental results showed that 1, 2 and 3 can be used as HEDMs in the field of combustion promoters and insensitive 2 can be regarded as a safer form for mass storage and transportation than sensitive 3.

  11. Technological and material related challenges for large area, high aspect-ratio, near teradot/inch2 areal density and three-dimensional structuring of polyaniline.

    Science.gov (United States)

    Jedrasik, Piotr; Vlad, Alexandru; Södervall, Ulf

    2011-10-01

    In this manuscript we report on a newly developed technology for the nanoscale processing of the conducting polyaniline (PANI) with an unprecedented areal patterning order and density control exceeding 0.25 teradot/inch2. High resolution electron beam lithography was used to generate ordered 2D and 3D templates. A novel type of resist and dose-modulated 3D-electron beam lithography (RDM-3D-EBL), extensively exploiting the intrinsic properties of resist-electron beam interaction is detailed. Surface initiated and template confined aniline polymerization, through catalytic activity of metallic platinum, was then exploited to provide a genuine method for controlled nanoscale processing of polyaniline, a prototypical conjugated polymer that definitively settled the concept of synthetic metals. Using nanoscale polymerization reactors, ultimate resolution patterning and processing control of single polyaniline nanostructures was feasible. Aspects of the nanoscale polyaniline growth mechanism are discussed and the highly controllable, sub-picogram scale fabrication is emphasized. Near teradot/inch2 pattern transfer technology, complex 3D structuring and physico-chemical functionalization of polyaniline can be subsequently harnessed to build a large variety of architectures with potential for emerging optoelectronic technologies. The method is scalable, can be applied on virtually any type of flexible or rigid substrates and provides a generic approach for nanopatterning surfaces with functional polymers. Technological and material related fabrication challenges are detailed and discussed.

  12. Benchmarking Density Functional Theory Based Methods To Model NiOOH Material Properties: Hubbard and van der Waals Corrections vs Hybrid Functionals.

    Science.gov (United States)

    Zaffran, Jeremie; Caspary Toroker, Maytal

    2016-08-09

    NiOOH has recently been used to catalyze water oxidation by way of electrochemical water splitting. Few experimental data are available to rationalize the successful catalytic capability of NiOOH. Thus, theory has a distinctive role for studying its properties. However, the unique layered structure of NiOOH is associated with the presence of essential dispersion forces within the lattice. Hence, the choice of an appropriate exchange-correlation functional within Density Functional Theory (DFT) is not straightforward. In this work, we will show that standard DFT is sufficient to evaluate the geometry, but DFT+U and hybrid functionals are required to calculate the oxidation states. Notably, the benefit of DFT with van der Waals correction is marginal. Furthermore, only hybrid functionals succeed in opening a bandgap, and such methods are necessary to study NiOOH electronic structure. In this work, we expect to give guidelines to theoreticians dealing with this material and to present a rational approach in the choice of the DFT method of calculation.

  13. Resistance of different materials used in sewers systems:Polyvinyl chloride (PVC, polypropylene (PP and High density polyethylene (HDPE, to sulfuric acid and sodium sulfate attack.

    Directory of Open Access Journals (Sweden)

    LASFAR Sara

    2014-02-01

    Full Text Available The behaviour of PVC, PP and HDPE used in sewer systems exposed to acid and sulfate solutions was investigated at 25°C and 40°C. Gravimetric characterization proves that PVC has a fickian behavior. It shows also, that PP has a non-fickian behavior, characterized by a rapid acceleration of water absorption, and the HDPE has a fickian behavior at 25°C, while it has a non-fickian behavior at 40°C, characterized by a weight loss after a certain aging period. The prolongation of the time of exposure to sulfuric acid solution leads to a progressive increase in tensile strength followed by a slight decrease at 40°C. The unaged samples of all materials have a much lower tensile strength than those of the aged samples, and a drop in elongation at break could be observed. These results can be explained by the increase of crystallinity, followed by the increase of crosslinking density due to the diffusion of the solvent and the effect of the temperature as the exposure time increases. These results prove that there is a correlation between the diffusion of the solvent as well as the increased exposure time and temperature on the mechanical properties of polymer.

  14. It`s not always quantity that counts. The apparent density of insulating material made of mineral wool may be a misleading quality criterion; Masse muss nicht Klasse sein. Warum die Rohdichte von Mineralwolle-Daemmstoffen ein irrefuehrendes Qualitaetsmerkmal ist

    Energy Technology Data Exchange (ETDEWEB)

    Royar, J.

    1995-10-01

    The apparent density of insulating material made of mineral wool is a popular quality criterion that can be assessed easily but does not allow one to evaluate materials reliably. It is not the only characteristic property of such materials and it should always be used in combination with other parameters. Requirements should be based on the relevant material data, i.e. on the thermal conductivity, behavior in fire, dynamic stiffness, sound absorption properties, and mechanical strength of insulating material made of mineral wool. (orig./HW) [Deutsch] Die Rohdichte von Mineralwolle-Daemmstoffen ist zwar eine leicht feststellbare Groesse und erfreut sich grosser Beliebtheit bei der vermeintlich sicheren Beurteilung der Qualitaet. Sie ist jedoch allein niemals und nur im Verbund mit anderen Materialparametern eine kennzeichnende Eigenschaft von Mineralwolle-Daemmstoffen. Bei der Formulierung von Anforderungen sollte man sich demnach auf die relevanten Materialdaten von MW-Daemmstoffen beschraenken: Waermeleitfaehigkeit, Brandverhalten, dynamische Steifigkeit, Schallabsorptionsvermoegen, mechanische Festigkeit. (orig./HW)

  15. Road density

    Data.gov (United States)

    U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...

  16. Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice

    NARCIS (Netherlands)

    Willige, van R.W.G.; Linssen, J.P.H.; Legger, A.; Voragen, A.G.J.

    2003-01-01

    The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic

  17. Bis[3-(5-nitroimino-1,2,4-triazolate)]-based energetic salts: synthesis and promising properties of a new family of high-density insensitive materials.

    Science.gov (United States)

    Wang, Ruihu; Xu, Hongyan; Guo, Yong; Sa, Rongjian; Shreeve, Jean'ne M

    2010-09-01

    Bis[3-(5-nitroimino-1,2,4-triazolate)]-based energetic salts were synthesized in a simple, straightforward manner. They exhibit low solubility in available solvents, high hydrolytic stability, excellent thermal stability, high density, positive heat of formation, low shock sensitivity, and excellent detonation properties. The physical and energetic properties of some salts are similar and even superior to those of RDX.

  18. Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice

    NARCIS (Netherlands)

    Willige, van R.W.G.; Linssen, J.P.H.; Legger, A.; Voragen, A.G.J.

    2003-01-01

    The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic f

  19. Screened-exchange density functional theory description of the electronic structure and phase stability of the chalcopyrite materials AgInSe2 and AuInSe2

    Science.gov (United States)

    Kim, Namhoon; Martin, Pamela Peña; Rockett, Angus A.; Ertekin, Elif

    2016-04-01

    We present a systematic assessment of the structural properties, the electronic density of states, the charge densities, and the phase stabilities of AgInSe2 and AuInSe2 using screened-exchange hybrid density functional theory, and compare their properties to those of CuInSe2. For AgInSe2, hybrid density functional theory properly captures several experimentally measured properties, including the increase in the band gap and the change in the direction of the lattice distortion parameter u in comparison to CuInSe2. While the electronic properties of AuInSe2 have not yet been experimentally characterized, we predict it to be a small gap (≈0.15 eV) semiconductor. We also present the phase stability of AgInSe2 and AuInSe2 according to screened-exchange density functional theory, and compare the results to predictions from conventional density functional theory, results tabulated from several online materials data repositories, and experiment (when available). In comparison to conventional density functional theory, the hybrid functional predicts phase stabilities of AgInSe2 in better agreement with experiment: discrepancies in the calculated formation enthalpies are reduced by approximately a factor of 3, from ≈0.20 eV/atom to ≈0.07 eV/atom, similar to the improvement observed for CuInSe2. We further predict that AuInSe2 is not a stable phase, and can only be present under nonequilibrium conditions.

  20. High-energy diffraction microscopy at the advanced photon source

    DEFF Research Database (Denmark)

    Lienert, U.; Li, S. F.; Hefferan, C. M.

    2011-01-01

    The status of the High Energy Diffraction Microscopy (HEDM) program at the 1-ID beam line of the Advanced Photon Source is reported. HEDM applies high energy synchrotron radiation for the grain and sub-grain scale structural and mechanical characterization of polycrystalline bulk materials in situ...

  1. Lung density

    DEFF Research Database (Denmark)

    Garnett, E S; Webber, C E; Coates, G

    1977-01-01

    The density of a defined volume of the human lung can be measured in vivo by a new noninvasive technique. A beam of gamma-rays is directed at the lung and, by measuring the scattered gamma-rays, lung density is calculated. The density in the lower lobe of the right lung in normal man during quiet...... breathing in the sitting position ranged from 0.25 to 0.37 g.cm-3. Subnormal values were found in patients with emphsema. In patients with pulmonary congestion and edema, lung density values ranged from 0.33 to 0.93 g.cm-3. The lung density measurement correlated well with the findings in chest radiographs...... but the lung density values were more sensitive indices. This was particularly evident in serial observations of individual patients....

  2. Assessment of the failure behavior of dangerous goods containers made of high density polyethylene using relevant material parameters; Beurteilung des Versagensverhaltens von Gefahrengutbehaeltern aus Polyethylen hoher Dichte auf Basis relevanter Werkstoffkennwerte

    Energy Technology Data Exchange (ETDEWEB)

    Menrad, Andreas

    2013-09-01

    To obtain approval as dangerous goods packaging, different experimental tests are required to show the eligibility for the transportation of those goods. The data obtained from the material test performed on the pressed plates is not used to get absolute values for the failure time in an internal pressure test or the medium drop height. The goal is to see if there are changes in the behavior because a different HDPE is being used. All the jerrycans and pressed plates were specially made of four different materials to gain knowledge about the material properties. The plates and jerrycans were made of resin from the same batch to prevent variations caused by batch differences. The wall thickness is decisive and, therefore packagings were analyzed using computer tomography and the fringe projection technique. The results were compared to the magnetostatic measurement technique. The deformation under internal pressure was measured by digital image correlation. Deformations in the radial direction and the equivalent strains were determined. These deformations, strains, and their acceleration due to the swelling effect could be reproduced in the finite element analysis by using the temperature in the material model. The resistance against both internal pressure and absorption depend on the density of the material. Conditioning at elevated temperatures causes post crystallization and reduces internal stresses. Differences in the densities of the materials can be determined by using plates manufactured by compression molding. A higher density leads to a better performance under internal pressure. A correlation could be proved between the medium failure drop height (50 % of the packagings fail because of a crack) and the tensile impact strength of notched specimens cut out of the jerrycans side walls and the notched impact strength (NIS) of pressed plates. A higher NIS leads to a higher medium failure drop height. A low resistance against oxidative degradation will reduce

  3. The Weighted Burgers Vector: a new quantity for constraining dislocation densities and types using electron backscatter diffraction on 2D sections through crystalline materials.

    Science.gov (United States)

    Wheeler, J; Mariani, E; Piazolo, S; Prior, D J; Trimby, P; Drury, M R

    2009-03-01

    The Weighted Burgers Vector (WBV) is defined here as the sum, over all types of dislocations, of [(density of intersections of dislocation lines with a map) x (Burgers vector)]. Here we show that it can be calculated, for any crystal system, solely from orientation gradients in a map view, unlike the full dislocation density tensor, which requires gradients in the third dimension. No assumption is made about gradients in the third dimension and they may be non-zero. The only assumption involved is that elastic strains are small so the lattice distortion is entirely due to dislocations. Orientation gradients can be estimated from gridded orientation measurements obtained by EBSD mapping, so the WBV can be calculated as a vector field on an EBSD map. The magnitude of the WBV gives a lower bound on the magnitude of the dislocation density tensor when that magnitude is defined in a coordinate invariant way. The direction of the WBV can constrain the types of Burgers vectors of geometrically necessary dislocations present in the microstructure, most clearly when it is broken down in terms of lattice vectors. The WBV has three advantages over other measures of local lattice distortion: it is a vector and hence carries more information than a scalar quantity, it has an explicit mathematical link to the individual Burgers vectors of dislocations and, since it is derived via tensor calculus, it is not dependent on the map coordinate system. If a sub-grain wall is included in the WBV calculation, the magnitude of the WBV becomes dependent on the step size but its direction still carries information on the Burgers vectors in the wall. The net Burgers vector content of dislocations intersecting an area of a map can be simply calculated by an integration round the edge of that area, a method which is fast and complements point-by-point WBV calculations.

  4. Generation of intense X-radiation and high-energy-density matter by laser-accelerated electrons; Erzeugung von intensiver Roentgenstrahlung und Materie hoher Energiedichte durch Laserbeschleunigte Elektronen

    Energy Technology Data Exchange (ETDEWEB)

    Schoenlein, Andreas

    2015-07-01

    Aim of this thesis was to study the processes of the interaction between highly intense short-pulse laser and matter. The focus lied thereby on the generation of intense X-radiation and warm dense matter. The studies performed for this thesis comprehend thereby the influence of laser parameters like energy, pulse length, focus size, and intensity as well as the influence of the target geometry on the interaction and generation of high-energy-density matter. In this thesis for this two selected experiments are presented. First a silver foil was used as target, in order to study the generation of radiation at 21 keV. Both bremsstrahlung and characteristic X-radiation were used in order to characterize the interaction. For the second experiment freely standing titanium wires were used as target. Hereby the focus lied on the characterization of the heated matter.

  5. Poly(vinylidene fluoride-co-hexafluoropropylene)-graft-poly(dopamine methacrylamide) copolymers: A nonlinear dielectric material for high energy density storage

    Science.gov (United States)

    Rahimabady, Mojtaba; Qun Xu, Li; Arabnejad, Saeid; Yao, Kui; Lu, Li; Shim, Victor P. W.; Gee Neoh, Koon; Kang, En-Tang

    2013-12-01

    A nonlinear dielectric poly(vinylidene fluoride-co-hexafluoropropylene)-graft-poly(dopamine methacrylamide) [P(VDF-HFP)-g-PDMA] graft copolymer with ultra-high energy density of 33 J/cm3 was obtained by thermally initiated radical graft polymerization. It was observed that the dielectric constant of the graft copolymer films was 63% higher than that of P(VDF-HFP), with a large dielectric breakdown strength (>850 MV/m). Theoretical analyses and experimental measurements showed that the significant improvement in the electric polarization was attributed to the introduction of the highly polarizable hydroxyl groups in the PDMA side chains, and the large breakdown strength arose from the strong adhesion bonding of the catechol-containing graft copolymer to the metal electrode.

  6. Studies of protein adsorption on implant materials in relation to biofilm formation I. Activity of Pseudomonas aeruginosa on Polypropylene and High density Polyethylene in presence of serum albumin

    CERN Document Server

    Sinha, S Dutta; Maity, P K; Tarafdar, S; Moulik, S P

    2014-01-01

    The surface of biomaterials used as implants are highly susceptible to bacterial colonization and subsequent infection. The amount of protein adsorption on biomaterials, among other factors, can affect the nature and quality of biofilms formed on them. The variation in the adsorption time of the protein on the biomaterial surface produces a phenotypic change in the bacteria by alteration of the production of EPS (exoplysaccharide) matrix. Knowledge of the effects of protein adsorption on implant infection will be very useful in understanding the chemistry of the biomaterial surfaces, which can deter the formation of biofilms. It is observed that the adsorption of BSA on the biomaterial surfaces increases with time and concentration, irrespective of their type and the nature of the EPS matrix of the bacterial biofilm is dependent on the amount of protein adsorbed on the biomaterial surface. The adsorption of protein (BSA) on the biomaterials, polypropylene (PP) and high density polyethylene (HDPE) has been stu...

  7. High energy density of Li3-xNaxV2(PO4)3/C cathode material with high rate cycling performance for lithium-ion batteries

    Science.gov (United States)

    Zuo, Zong-Lin; Deng, Jian-Qiu; Pan, Jin; Luo, Wen-Bin; Yao, Qing-Rong; Wang, Zhong-Min; Zhou, Huai-Ying; Liu, Hua-Kun

    2017-07-01

    A serials of micro-sized Li3-xNaxV2(PO4)3/C composite has been synthesized by sol-gel method, comprised of numerous primary nanocrystals. This structure can efficiently facilitate lithium-ion transport in secondary aggregated individual particles due to the short diffusion distance among primary nanocrystals, along with a high tap density. With the increasing of Na doping content, the structure evolution occurs in Li3-xNaxV2(PO4)3 from a single-phase structure to a two-phase structure. The appearance of rhombohedral phase can provide a larger free volume of the interstitial space, fastening ionic movement to offer an excellent high rate capability. Furthermore, Na doping can stabilize the rhombohedral structure of the V2(PO4)3 framework, leading to the remarkable cycling stability. Among all the composites, Li2.6Na0.4V2(PO4)3/C presents the best electrochemical performance with a high energy density of 478.8 Wh kg-1, delivering high initial discharge capacities of 121.6, 113.8 and 109.7 mAh g-1 at the rate of 5 C, 10 C and 20 C in a voltage range of 3.0 - 4.3 V, respectively. It also exhibit an excellent high rate cycling performance, with capacity retention of 85.9 %, 81.7 % and 76.5 % after 1000 cycles at the rate of 5 C, 10 C and 20 C in a voltage range of 3.0 - 4.3 V.

  8. MOF-derived crumpled-sheet-assembled perforated carbon cuboids as highly effective cathode active materials for ultra-high energy density Li-ion hybrid electrochemical capacitors (Li-HECs)

    Science.gov (United States)

    Banerjee, Abhik; Upadhyay, Kush Kumar; Puthusseri, Dhanya; Aravindan, Vanchiappan; Madhavi, Srinivasan; Ogale, Satishchandra

    2014-03-01

    Lithium ion hybrid capacitors (Li-HECs) have attracted significant attention for use in next generation advanced energy storage technologies to satisfy the demand of both high power density as well as energy density. Herein we demonstrate the use of very high surface area 3D carbon cuboids synthesized from a metal-organic framework (MOF) as a cathode material with Li4Ti5O12 as the anode for high performance Li-HECs. The energy density of the cell is ~65 W h kg-1 which is significantly higher than that achievable with commercially available activated carbon (~36 W h kg-1) and a symmetric supercapacitor based on the same MOF-derived carbon (MOF-DC ~20 W h kg-1). The MOF-DC/Li4Ti5O12 Li-HEC assembly also shows good cyclic performance with ~82% of the initial value (~25 W h kg-1) retained after 10 000 galvanostatic cycles under high rate cyclic conditions. This result clearly indicates that MOF-DC is a very promising candidate for future P-HEVs in a Li-HEC configuration.Lithium ion hybrid capacitors (Li-HECs) have attracted significant attention for use in next generation advanced energy storage technologies to satisfy the demand of both high power density as well as energy density. Herein we demonstrate the use of very high surface area 3D carbon cuboids synthesized from a metal-organic framework (MOF) as a cathode material with Li4Ti5O12 as the anode for high performance Li-HECs. The energy density of the cell is ~65 W h kg-1 which is significantly higher than that achievable with commercially available activated carbon (~36 W h kg-1) and a symmetric supercapacitor based on the same MOF-derived carbon (MOF-DC ~20 W h kg-1). The MOF-DC/Li4Ti5O12 Li-HEC assembly also shows good cyclic performance with ~82% of the initial value (~25 W h kg-1) retained after 10 000 galvanostatic cycles under high rate cyclic conditions. This result clearly indicates that MOF-DC is a very promising candidate for future P-HEVs in a Li-HEC configuration. Electronic supplementary information

  9. High-Density Magnetic Recording and Integrated Magneto-Optics: Materials and Devices; Symposium Held in San Francisco, California, on April 12-16 1998

    Science.gov (United States)

    1998-04-01

    Veloso1,2, P. P. Freitas1,2, J. Fernandes3, M. Ferreira3 ’instituto de Engenharia de Sistemas e Computadores (INESC), R. Alves Redol 9, 1000 Lisboa...Freitasa’b, T.T. Galväoab, JJ. Sun", V. Soares", A. Klingc’d, M.F. da Silva’, and J.C. Soarescd ’Institute de Engenharia de Sistemas e Computadores (INESC...is remarkable that an amor - phous material that is half hydrogen has a hardness comparable to that of single-crystal silicon. We suggested that the

  10. Density functional investigation of mercury and arsenic adsorption on nitrogen doped graphene decorated with palladium clusters: A promising heavy metal sensing material in farmland

    Science.gov (United States)

    Zhao, Chunjiang; Wu, Huarui

    2017-03-01

    Density functional theory calculations are carried out to study the adsorption of mercury and arsenic on Pdn (n = 1-6) supported on pyridine-like nitrogen doped graphene (PNG). Owing to the promising sensitivity in trace amounts of atoms or molecules, PNG can be acted as micro-sensor for sensing heavy metals in agriculture soils. Through the analyses of structural and electronic properties of pristine PNG and Pd atom decorated PNG, we find that the most favorable adsorption site for Pd atom is the vacancy site. The analyses of structural and electronic properties reveal that the Pd atom or clusters can enhance the reactivity for Hg and AsH3 adsorption on PNG. The adsorption ability of Hg on Pdn decorated PNG is found to be related to the d-band center (εd) of the Pdn, in which the closer εd of Pdn to the Fermi level, the higher adsorption strength for Hg on Pdn decorated PNG. Moreover, the charge transfer between Pdn and arsenic may constitute arsenic adsorption on Pdn decorated PNG. Further design of highly efficient carbon based sorbents for heavy metals removal should be focused on tailoring εd of adsorbed metals.

  11. Influence of flavour absorption by food-packaging materials (low-density polyethylene, polycarbonate and polyethylene terephthalate) on taste perception of a model solution and orange juice.

    Science.gov (United States)

    Van Willige, R W G; Linssen, J P H; Legger-Huysman, A; Voragen, A G J

    2003-01-01

    The influence of flavour absorption by low-density polyethylene (LDPE), polycarbonate (PC) and polyethylene terephthalate (PET) on taste perception of a model solution containing seven flavour compounds and orange juice in glass bottles was studied with and without pieces of the respective plastic films after dark storage at 20 degrees C. Owing to absorption, the amount of flavour compounds in the model solution exposed to LDPE decreased substantially. From the model flavour solution valencene was almost completely absorbed by LDPE, followed to a lesser extent by decanal, hexyl acetate, octanal and nonanone. Less flavour compounds were absorbed from the model solution by PC and PET. In contrast to LDPE, valencene was absorbed in the lowest amounts and decanal in the highest. Limonene was readily absorbed from orange juice by LDPE, while myrcene, valencene, pinene and decanal were absorbed in smaller quantities. Only three flavour compounds were absorbed from orange juice by PC and PET in very small amounts: limonene, myrcene and decanal. Although the flavour content between controls and polymer-treated samples differed substantially, the loss of flavour compounds due to absorption by LDPE, PC and PET did not influence taste perception of a model solution and orange juice significantly up to 29 days of dark storage at 20 degrees C as determined by triangular taste panel tests.

  12. Blending of Low-Density Polyethylene and Poly-Lactic Acid with Maleic Anhydride as A Compatibilizer for Better Environmentally Food-Packaging Material

    Science.gov (United States)

    Setiawan, A. H.; Aulia, F.

    2017-05-01

    The common conventional food packaging materialsare using a thin layer plastic or film, which is made of a synthetic polymer, such as Low-Density Poly Ethylene (LDPE). However, the use of these polymers hasan adverse impact on the environment, because the synthetic polymersare difficult to degrade naturally. Poly-Lactic Acid (PLA) is a biodegradable polymer that can be substituted to synthetic polymers. Since LDPE and PLA have a difference in polarity, therefore the first step of research is to graft them with maleic anhydride (MAH) for increasing the properties of its miscibility. The interaction between them is confirmed by FTIR; whereas the environment issueis characterized by the water adsorption and biodegradability. The FTIR spectra indicated that there had been an interaction between LDPE and MAH and LDPE/LDPE-g-MAH/PLA blend. Increasing PLA content in the blend affected to the increasing in their water absorption and biodegradable. Poly-blend with 20% PLA content was the optimum composition for environmentally food packaging.

  13. Current Issues in Finite-T Density-Functional Theory and Warm-Correlated Matter †

    Directory of Open Access Journals (Sweden)

    M. W. C. Dharma-wardana

    2016-03-01

    Full Text Available Finite-temperature density functional theory (DFT has become of topical interest, partly due to the increasing ability to create novel states of warm-correlated matter (WCM.Warm-dense matter (WDM, ultra-fast matter (UFM, and high-energy density matter (HEDM may all be regarded as subclasses of WCM. Strong electron-electron, ion-ion and electron-ion correlation effects and partial degeneracies are found in these systems where the electron temperature Te is comparable to the electron Fermi energy EF. Thus, many electrons are in continuum states which are partially occupied. The ion subsystem may be solid, liquid or plasma, with many states of ionization with ionic charge Zj. Quasi-equilibria with the ion temperature Ti ≠ Te are common. The ion subsystem in WCM can no longer be treated as a passive “external potential”, as is customary in T = 0 DFT dominated by solid-state theory or quantum chemistry. Many basic questions arise in trying to implement DFT for WCM. Hohenberg-Kohn-Mermin theory can be adapted for treating these systems if suitable finite-T exchange-correlation (XC functionals can be constructed. They are functionals of both the one-body electron density ne and the one-body ion densities ρj. Here, j counts many species of nuclei or charge states. A method of approximately but accurately mapping the quantum electrons to a classical Coulomb gas enables one to treat electron-ion systems entirely classically at any temperature and arbitrary spin polarization, using exchange-correlation effects calculated in situ, directly from the pair-distribution functions. This eliminates the need for any XC-functionals. This classical map has been used to calculate the equation of state of WDM systems, and construct a finite-T XC functional that is found to be in close agreement with recent quantum path-integral simulation data. In this review, current developments and concerns in finite-T DFT, especially in the context of non-relativistic warm

  14. An In-situ materials analysis particle probe (MAPP) diagnostic to study particle density control and hydrogenic fuel retention in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    Allain, Jean-Paul [Purdue Univ., West Lafayette, IN (United States)

    2014-09-05

    A new materials analysis particle probe (MAPP) was designed, constructed and tested to develop understanding of particle control and hydrogenic fuel retention in lithium-based plasma-facing surfaces in NSTX. The novel feature of MAPP is an in-situ tool to probe the divertor NSTX floor during LLD and lithium-coating shots with subsequent transport to a post-exposure in-vacuo surface analysis chamber to measure D retention. In addition, the implications of a lithiated graphite-dominated plasma-surface environment in NSTX on LLD performance, operation and ultimately hydrogenic pumping and particle control capability are investigated in this proposal. MAPP will be an invaluable tool for erosion/redeposition simulation code validation.

  15. MOF-derived crumpled-sheet-assembled perforated carbon cuboids as highly effective cathode active materials for ultra-high energy density Li-ion hybrid electrochemical capacitors (Li-HECs).

    Science.gov (United States)

    Banerjee, Abhik; Upadhyay, Kush Kumar; Puthusseri, Dhanya; Aravindan, Vanchiappan; Madhavi, Srinivasan; Ogale, Satishchandra

    2014-04-21

    Lithium ion hybrid capacitors (Li-HECs) have attracted significant attention for use in next generation advanced energy storage technologies to satisfy the demand of both high power density as well as energy density. Herein we demonstrate the use of very high surface area 3D carbon cuboids synthesized from a metal-organic framework (MOF) as a cathode material with Li₄Ti₅O₁₂ as the anode for high performance Li-HECs. The energy density of the cell is ∼65 W h kg(-1) which is significantly higher than that achievable with commercially available activated carbon (∼36 W h kg(-1)) and a symmetric supercapacitor based on the same MOF-derived carbon (MOF-DC ∼20 W h kg(-1)). The MOF-DC/Li₄Ti₅O₁₂ Li-HEC assembly also shows good cyclic performance with ∼82% of the initial value (∼25 W h kg(-1)) retained after 10,000 galvanostatic cycles under high rate cyclic conditions. This result clearly indicates that MOF-DC is a very promising candidate for future P-HEVs in a Li-HEC configuration.

  16. Fast-Rate Capable Electrode Material with Higher Energy Density than LiFePO4: 4.2V LiVPO4F Synthesized by Scalable Single-Step Solid-State Reaction.

    Science.gov (United States)

    Kim, Minkyung; Lee, Seongsu; Kang, Byoungwoo

    2016-03-01

    Use of compounds that contain fluorine (F) as electrode materials in lithium ion batteries has been considered, but synthesizing single-phase samples of these compounds is a difficult task. Here, it is demonstrated that a simple scalable single-step solid-state process with additional fluorine source can obtain highly pure LiVPO4F. The resulting material with submicron particles achieves very high rate capability ≈100 mAh g(-1) at 60 C-rate (1-min discharge) and even at 200 C-rate (18 s discharge). It retains superior capacity, ≈120 mAh g(-1) at 10 C charge/10 C discharge rate (6-min) for 500 cycles with >95% retention efficiency. Furthermore, LiVPO4F shows low polarization even at high rates leading to higher operating potential >3.45 V (≈3.6 V at 60 C-rate), so it achieves high energy density. It is demonstrated for the first time that highly pure LiVPO4F can achieve high power capability comparable to LiFePO4 and much higher energy density (≈521 Wh g(-1) at 20 C-rate) than LiFePO4 even without nanostructured particles. LiVPO4F can be a real substitute of LiFePO4.

  17. Movimento e inativação do metribuzin em materiais de dois solos, sob diferentes densidades aparentes Movement and inactivation of metribuzin in two soil materials with different bulk densities

    Directory of Open Access Journals (Sweden)

    L.E.F. Fontes

    1980-06-01

    Full Text Available Numa série de ensaios em laboratório e casa-de-vegetação, estudou-se a mobilidade e a inativação do herbicida metribuzin em materiais de um Latossolo e de um Podzólico representativos de duas regiões do Estado de Minas Gerais, em função de diferentes densidades aparentes. Ensaios biológicos foram utilizados para medir a inativação e a mobilidade do metribuzin nos diferentes solos e densidades. A densidade aparente alterou de forma pronunciada a quantidade de herbicida lixiviado através das colunas dos materiais dos solos estudados. Quanto maior a densidade, menor a quantidade de herbicida lixiviado. A quantidade de herbicida que permaneceu biologicamente ativo ao longo da coluna foi diretamente relacionada com a densidade, em cada solo. A mobilidade do metribuzin no material do Latossolo foi maior que no de Podzólico, em consequência de maior atividade coloidal deste.The leaching and inactivation of metribuzin were studied with materials of two mineral soilsat different bulk densities. Plastic tubing of' 7.25 cm diameter and 10 cm height were filled up with different amounts of soil to get different bulk densities. One kg/ha of a.i. of metribuzin placed on the surface are a of the column was le ached through these soil colums using 250 ml of water. The cotyledon disk bioassay method was used to detect the metribuzin leachet. The biological active metribuzin in the soil colunn at different depths, and the inativation abil ity of the soils were determined using the assay with cucumber (Cucumis sativus L. as test-plant. The increase of bulk density reduced the leaching and enhanced the biologically active metribuzin in the soil column. Metribuzin was more mobil in the Red -yellow Lato ssol and more inactivated in the Red-yellow Podzolic soils.

  18. History and modern applications of nano-composite materials carrying GA/cm2 current density due to a Bose-Einstein Condensate at room temperature produced by Focused Electron Beam Induced Processing for many extraordinary novel technical applications

    Science.gov (United States)

    Koops, Hans W. P.

    2015-12-01

    The discovery of Focused Electron Beam Induced Processing and early applications of this technology led to the possible use of a novel nanogranular material “Koops-GranMat®” using Pt/C and Au/C material. which carries at room temperature a current density > 50 times the current density which high TC superconductors can carry. The explanation for the characteristics of this novel material is given. This fact allows producing novel products for many applications using Dual Beam system having a gas supply and X.Y.T stream data programming and not using GDSII layout pattern control software. Novel products are possible for energy transportation. -distribution.-switching, photon-detection above 65 meV energy for very efficient energy harvesting, for bright field emission electron sources used for vacuum electronic devices like amplifiers for HF electronics, micro-tubes, 30 GHz to 6 THz switching amplifiers with signal to noise ratio >10(!), THz power sources up to 1 Watt, in combination with miniaturized vacuum pumps, vacuum gauges, IR to THz detectors, EUV- and X-Ray sources. Since focusing electron beam induced deposition works also at low energy, selfcloning multibeam-production machines for field emitter lamps, displays, multi-beam - lithography, - imaging, and - inspection, energy harvesting, and power distribution with switches controlling field-emitter arrays for KA of currents but with < 100 V switching voltage are possible. Finally the replacement of HTC superconductors and its applications by the Koops-GranMat® having Koops-Pairs at room temperature will allow the investigation devices similar to Josephson Junctions and its applications now called QUIDART (Quantum interference devices at Room Temperature). All these possibilities will support a revolution in the optical, electric, power, and electronic technology.

  19. Preparation, thermal and flammability properties of a novel form-stable phase change materials based on high density polyethylene/poly(ethylene-co-vinyl acetate)/organophilic montmorillonite nanocomposites/paraffin compounds

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yibing [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027 (China); Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi, Jiangsu 214122 (China); Song, Lei; He, Qingliang; Yang, Dandan; Hu, Yuan [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2008-08-15

    The paraffin is one of important thermal energy storage materials with many desirable characteristics (i.e., high heat of fusion, varied phase change temperature, negligible supercooling, self-nucleating, no phase segregation and cheap, etc.), but has low thermal stability and flammable. Hence, a novel form-stable phase change materials (PCM) based on high density polyethylene (HDPE)/poly(ethylene-co-vinyl acetate) (EVA)/organophilic montmorillonite (OMT) nanocomposites and paraffin are prepared by twin-screw extruder technique. The structures of the HDPE-EVA/OMT nanocomposites and the form-stable PCM are evidenced by the X-ray diffraction (XRD), transmission electronic microscopy (TEM) and scanning electronic microscope (SEM). The results of XRD and TEM show that the HDPE-EVA/OMT nanocomposites form the ordered intercalated nanomorphology. The form-stable PCM consists of the paraffin, which acts as a dispersed phase change material and the HDPE-EVA/OMT nanocomposites, which acts as the supporting material. The paraffin disperses in the three-dimensional net structure formed by HDPE-EVA/OMT nanocomposites. The thermal stability, latent heat and flammability properties are characterized by thermogravimetry analysis (TGA), dynamic Fourier-transform infrared (FTIR), differential scanning calorimeter (DSC) and cone calorimeter, respectively. The TGA and dynamic FTIR analyses indicate that the incorporation of suitable amount of OMT into the form-stable PCM increase the thermal stability. The DSC results show that the latent heat of the form-stable PCM has a certain degree decrease. The cone calorimeter shows that the heat release rate (HRR) has remarkably decreases with loading of OMT in the form-stable PCM, contributing to the improved flammability properties. (author)

  20. Preparation, thermal and flammability properties of a novel form-stable phase change materials based on high density polyethylene/poly(ethylene-co-vinyl acetate)/organophilic montmorillonite nanocomposites/paraffin compounds

    Energy Technology Data Exchange (ETDEWEB)

    Cai Yibing [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027 (China); Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi, Jiangsu 214122 (China); Song Lei [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027 (China)], E-mail: leisong@ustc.edu.cn; He Qingliang; Yang Dandan; Hu Yuan [State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2008-08-15

    The paraffin is one of important thermal energy storage materials with many desirable characteristics (i.e., high heat of fusion, varied phase change temperature, negligible supercooling, self-nucleating, no phase segregation and cheap, etc.), but has low thermal stability and flammable. Hence, a novel form-stable phase change materials (PCM) based on high density polyethylene (HDPE)/poly(ethylene-co-vinyl acetate) (EVA)/organophilic montmorillonite (OMT) nanocomposites and paraffin are prepared by twin-screw extruder technique. The structures of the HDPE-EVA/OMT nanocomposites and the form-stable PCM are evidenced by the X-ray diffraction (XRD), transmission electronic microscopy (TEM) and scanning electronic microscope (SEM). The results of XRD and TEM show that the HDPE-EVA/OMT nanocomposites form the ordered intercalated nanomorphology. The form-stable PCM consists of the paraffin, which acts as a dispersed phase change material and the HDPE-EVA/OMT nanocomposites, which acts as the supporting material. The paraffin disperses in the three-dimensional net structure formed by HDPE-EVA/OMT nanocomposites. The thermal stability, latent heat and flammability properties are characterized by thermogravimetry analysis (TGA), dynamic Fourier-transform infrared (FTIR), differential scanning calorimeter (DSC) and cone calorimeter, respectively. The TGA and dynamic FTIR analyses indicate that the incorporation of suitable amount of OMT into the form-stable PCM increase the thermal stability. The DSC results show that the latent heat of the form-stable PCM has a certain degree decrease. The cone calorimeter shows that the heat release rate (HRR) has remarkably decreases with loading of OMT in the form-stable PCM, contributing to the improved flammability properties.

  1. Synthesis, characterization, and energetic properties of 6-amino-tetrazolo[1,5-b]-1,2,4,5-tetrazine-7-N-oxide: a nitrogen-rich material with high density.

    Science.gov (United States)

    Wei, Hao; Zhang, Jiaheng; Shreeve, Jean'ne M

    2015-05-01

    The synthesis and energetic properties of a novel N-oxide high-nitrogen compound, 6-amino-tetrazolo[1,5-b]-1,2,4,5-tetrazine-7-N-oxide, are described. Resulting from the N-oxide and fused rings system, this molecule exhibits high density, excellent detonation properties, and acceptable impact and friction sensitivities, which suggests potential applications as an energetic material. Compared to known high-nitrogen compounds, such as 3,6-diazido-1,2,4,5-tetrazine (DiAT), 2,4,6-tri(azido)-1,3,5-triazine (TAT), and 4,4',6,6'-tetra(azido)azo-1,3,5-triazine (TAAT), a marked performance and stability increase is seen. This supports the superior qualities of this new compound and the advantage of design strategy.

  2. Ⅲ-Ⅴ family of semiconductor materials photonic crystal state density characteristics%Ⅲ-Ⅴ族半导体材料组成光子晶体能态密度特性

    Institute of Scientific and Technical Information of China (English)

    陈士芹

    2012-01-01

    Application of the plane wave expansion method research □-□ family of semiconductor materials photonic crystal can state density, get filled with a radius of grid work rate f the variations between the corresponding state density distribution, when f = 0.2 a normalized when frequency biggest photonic band gap. Through the comparison for semiconductor compound material, AlP AIAs,AISb GaP and a 2 d square photonic crystals that has a wide GaP of the photon belt, with filling rate increase photonic crystal increase. The results of photonic crystal devices to provide the theory basis.%应用平面波展开法研究Ⅲ-Ⅴ族半导体材料组成光子晶体能态密度特性,得到填充率f随品格半径a之间的变化对应的能态密度分布,当f=0.2a时归一化频率存在最大光子带隙。通过比较化合物半导体材料为AIP、AJAs、AISb和GaP构成二维方形光子晶体得出GaP有较宽的光子禁带,随着填充率的增加光子晶体带隙增加。研究结果为光子晶体器件的研究提供理论依据。

  3. Tuning of the vinyl groups' spacing at surface of modified silica in preparation of high density imprinted layer-coated silica nanoparticles: a dispersive solid-phase extraction materials for chlorpyrifos.

    Science.gov (United States)

    Lu, Qing; Chen, Xuemei; Nie, Li; Luo, Jing; Jiang, Huijun; Chen, Lina; Hu, Qin; Du, Shuhu; Zhang, Zhongping

    2010-05-15

    This paper reports the preparation of high density imprinted layer-coated silica nanoparticles toward selective recognition and fast enrichment of chlorpyrifos (CP) from complicated matrices. The molecularly imprinted polymers (MIPs) were successfully coated at the surface of modified silica through using the chemical immovable vinyl groups at the nanoparticles' surface, followed by the graft copolymerization of methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) in the presence of templates CP. It has been demonstrated that the space of end vinyl groups at the surface of silica can be controlled by changing the condition of chemical modification, regulating the thickness of imprinted shells and the density of efficient imprinted sites. After removal of templates by solvent extraction, the recognition sites of CP were created in the polymer coating layer. The CP-imprinted nanoparticles exhibited high recognition selectivity and binding affinity to CP analyte. When the CP-imprinted nanoparticles were used as dispersive solid-phase extraction (dSPE) materials, the high recovery yields of 76.1-93.5% from various spiked samples with only 1microg/mL analyte were achieved by one-step extraction. These results reported herein provide the possibility for the separation and enrichment of CP from complicated matrices by the molecular imprinting modification at the surface of common silica nanoparticles.

  4. Scientific Opinion on the safety evaluation of the process “Schoeller Arca Systems”, used to recycle polypropylene and high-density polyethylene crates for use as food contact material

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF

    2013-04-01

    Full Text Available This scientific opinion of the EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids deals with the safety evaluation of the recycling process “Schoeller Arca Systems”, EC register number RECYC075. The process recycles damaged food contact re-usable polypropylene (PP and high-density polyethylene (HDPE crates which have been used in a closed and controlled product loop into new recycled crates. Through this process, damaged crates are firstly ground into flakes which are further blended with virgin PP or HDPE or used at 100 % to manufacture new recycled PP and HDPE crates. The CEF Panel concluded that the input of the process “Schoeller Arca Systems” originates from a product loop which is in a closed and controlled chain ensuring that only materials and articles which have been intended for food contact are used and that any contamination can be ruled out when run under the conditions described by the applicant. The Panel considered that the repeated grinding and injection moulding of PP and HDPE crates, which is part of the recycling process, under conditions described by the applicant, is not of safety concern. Therefore the recycling process “Schoeller Arca Systems” is able to produce recycled PP and HDPE suitable for manufacturing crates intended to be used in contact at room temperature or below with meat, whole fruits and vegetables as requested by the applicant.

  5. Physico-chemical characterization, density functional theory (DFT) studies and Hirshfeld surface analysis of a new organic optical material: 1H-benzo[d]imidazol-3-ium-2,4,6-trinitrobenzene-1,3 bis(olate)

    Science.gov (United States)

    Dhamodharan, P.; Sathya, K.; Dhandapani, M.

    2017-10-01

    A novel organic crystal, 1H-benzo[d]imidazol-3-ium-2,4,6-trinitrobenzene-1,3 bis(olate) (BITB), was synthesized. Single crystals of BITB were harvested by solution growth-slow evaporation technique. 1H and 13C NMR spectroscopic techniques were utilized to confirm the presence of various types of carbons and protons in BITB. Single crystal XRD confirms that BITB crystallizes in monoclinic system with a space group of P21/n. The suitability of this material for optical applications was assessed by optical absorption, transmittance, reflectance and refractive index spectroscopic techniques. Gaussian 09 program at B3LYP/6-311++G(d,p) level of basis set as used for the optimization of molecular structure of BITB. Greater first order hyperpolarizability value of BITB is due to intensive hydrogen bond network in the crystal. The value is 15 times greater than that of Urea, a reference standard. Computation of frontier molecular orbitals and electrostatic potential surface helped to understand the electron density and reactive sites in BITB. The material was thermally stable up to 220 °C. Hirshfeld surface analysis was performed to quantify the covalent and non covalent interactions.

  6. Amorphous LiCoO2sbnd Li2SO4 active materials: Potential positive electrodes for bulk-type all-oxide solid-state lithium batteries with high energy density

    Science.gov (United States)

    Nagao, Kenji; Hayashi, Akitoshi; Deguchi, Minako; Tsukasaki, Hirofumi; Mori, Shigeo; Tatsumisago, Masahiro

    2017-04-01

    Newly amorphous Li2-x/100Cox/100S1-x/100O4-x/50 (xLiCoO2·(100-x)Li2SO4 (mol%)) positive electrode active materials are synthesized using mechanochemical techniques. SEM observation indicates that average radii of the Li1.2Co0.8S0.2O2.4 (80LiCoO2·20Li2SO4 (mol%)) particles are about 3 μm. HR-TEM images indicate that the particles comprise nano-crystalline and amorphous phases. The crystalline phase is attributable to cubic LiCoO2 phase. These active materials exhibit a high electronic conductivity of around 10-5-10-1 S cm-1 and an ionic conductivity of around 10-7-10-6 S cm-1 at room temperature. Bulk-type all-oxide solid-state cells (Lisbnd In alloy/Li3BO3-based glass-ceramic electrolyte/amorphous Li2-x/100Cox/100S1-x/100O4-x/50) are fabricated by pressing at room temperature without high temperature sintering. Although the cell with the milled LiCoO2 shows no capacity, the cell using the Li1.2Co0.8S0.2O2.4 electrode with no conductive components (ca. 150 μm thickness) operates as a secondary battery at 100 °C, with an average discharge potential of 3.3 V (vs. Li+/Li) and discharge capacity of 163 mAh g-1. A positive electrode with large amounts of active materials is suitable for achieving high energy density in all-solid-state batteries. These newly synthesized amorphous Li2-x/100Cox/100S1-x/100O4-x/50 electrodes with ionic and electronic conductivities and good processability meet that demand.

  7. 不同半导体材料构成光子晶体在太赫兹波段能态密度特性%State Density Properties of Photonic Crystal Composited by Different Semiconductor Material in Terahertz Band

    Institute of Scientific and Technical Information of China (English)

    邴丕彬; 闫昕

    2012-01-01

    Based on the plane wave expansion method research Ⅳ, Ⅲ-Ⅴ and Ⅱ- Ⅵ semiconductor material composition family 2d triangle photonic crystal lattice terahertz band state density of characteristics, numerical simulation to get Ⅳ family in filling SiC rate f = 0. 8 form 0. 037 THz band gap width, Ⅱ-Ⅵ ZnO family in filling rate f = 0. 73 form 0. 0417 THz band gap width form, the filler rate case Ⅲ-Ⅴ race semiconductor material form 0.027 THz band gap width, more data Ⅱ-Ⅵ race semiconductor material form more wide band gap, the result is too Hertz photonic crystal devices to provide the theoretical basis for development.%基于平面波展开法研究Ⅳ、Ⅲ-Ⅴ和Ⅱ-Ⅵ族半导体材料构成二维三角晶格光子晶体在太赫兹波段的能态密度特性,数值模拟得到Ⅳ族SiC在填充率f=0.8时形成0.037 THz带隙宽度,Ⅱ-Ⅵ族ZnO在填充率f=0.73时形成0.0417 THz带隙宽度,不同填充率情况下Ⅲ-Ⅴ族半导体材料形成0.027 THz带隙宽度,比较数据Ⅱ-Ⅵ族半导体材料形成较宽的带隙,研究结果为太赫兹光子晶体器件的开发提供了理论依据.

  8. Density states of photonic crystal with Ⅳ-Ⅵ family of Semiconducting material%Ⅳ-Ⅵ族半导体材料构成光子晶体能态密度特性

    Institute of Scientific and Technical Information of China (English)

    王发友

    2013-01-01

    应用平面波展开法,取Ⅳ-Ⅵ族的PbS、PbSe和PbTe半导体材料构成二维三角晶格光子晶体.数值模拟其构成光子晶体能态密度特性.结果表明,随着介电常数的增大,形成的光子带隙宽度增加.结论为光子晶体器件的开发提供参考.%Two-dimensional triangle lattice photonic crystal were consist of PbS,PbSe and PbTe Ⅳ-Ⅵ family of Semiconducting material,energy state density distribute of photonic crystal were calculated by plane wave expansion method.The results show that,with the increase of dielectric constant,form the photonic band gap width increases,the normalized frequency as filling rate changes.This result provides theoretic basis theoretic basis for the photonic crystal devices.

  9. Low Bone Density

    Science.gov (United States)

    ... Information › Bone Density Exam/Testing › Low Bone Density Low Bone Density Low bone density is when your ... compared to people with normal bone density. Detecting Low Bone Density A bone density test will determine ...

  10. Charge density waves in solids

    CERN Document Server

    Gor'kov, LP

    2012-01-01

    The latest addition to this series covers a field which is commonly referred to as charge density wave dynamics.The most thoroughly investigated materials are inorganic linear chain compounds with highly anisotropic electronic properties. The volume opens with an examination of their structural properties and the essential features which allow charge density waves to develop.The behaviour of the charge density waves, where interesting phenomena are observed, is treated both from a theoretical and an experimental standpoint. The role of impurities in statics and dynamics is considered and an

  11. Substituent effect on the molecular stability, group interaction, detonation performance, and thermolysis mechanism of nitroamino-substituted cyclopentanes and cyclohexanes

    Institute of Scientific and Technical Information of China (English)

    QIU Ling; GONG XueDong; JU XueHai; XIAO HeMing

    2008-01-01

    Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions ac-cord with the group additivity, increasing with the increasing number of nitroamino groups. The distance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a-9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative cri-teria of HEDM (ρ≈1.9 g/cm3, D≈9.0 km/s, P≈40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title com-pounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacy-clohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials.These results may provide basic information for the molecular design of HEDMs.

  12. Substituent effect on the molecular stability,group interaction,detonation performance,and thermolysis mechanism of nitroamino-substituted cyclopentanes and cyclohexanes

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Density functional theory (DFT) method has been employed to study the effect of nitroamino group as a substituent in cyclopentane and cyclohexane, which usually construct the polycyclic or caged nitra-mines. Molecular structures were investigated at the B3LYP/6-31G** level, and isodesmic reactions were designed for calculating the group interactions. The results show that the group interactions ac-cord with the group additivity, increasing with the increasing number of nitroamino groups. The dis-tance between substituents influences the interactions. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the predicted densities and heats of formation, while thermal stability and pyrolysis mechanism were studied by the computations of bond dissociation energy (BDE). It is found that the contributions of nitroamino groups to the detonation heat, detonation velocity, detonation pressure, and stability all deviate from the group additivity. Only 3a, 3b, and 9a-9c may be novel potential candidates of high energy density materials (HEDMs) according to the quantitative cri-teria of HEDM (ρ≈ 1.9 g/cm3, D ≈ 9.0 km/s, P ≈ 40.0 GPa). Stability decreases with the increasing number of N-NO2 groups, and homolysis of N-NO2 bond is the initial step in the thermolysis of the title com-pounds. Coupled with the demand of thermal stability (BDE > 20 kcal/mol), only 1,2,4-trinitrotriazacy-clohexane and 1,2,4,5-tetranitrotetraazacyclohexane are suggested as feasible energetic materials. These results may provide basic information for the molecular design of HEDMs.

  13. Giant magnetostrictive materials

    Institute of Scientific and Technical Information of China (English)

    LIU JingHua; JIANG ChengBao; XU HuiBin

    2012-01-01

    Giant magnetostrictive materials are a kind of functional materials developed since 1970s,known as their large magnetostrain and high energy density.In this paper,an introduction of magnetosttiction and the history of magnetostrictive materials are described firstly.Then we review the recent developments of both rare earth and non-rare earth magnetostrictive materials.Finally,the tendency of developing new giant magnetostrictive materials is presented.

  14. Concrete density estimation by rebound hammer method

    Science.gov (United States)

    Ismail, Mohamad Pauzi bin; Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri; Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin

    2016-01-01

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  15. Concrete density estimation by rebound hammer method

    Energy Technology Data Exchange (ETDEWEB)

    Ismail, Mohamad Pauzi bin, E-mail: pauzi@nm.gov.my; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri [NDT Group, Nuclear Malaysia, Bangi, Kajang, Selangor (Malaysia); Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin [Material Technology Program, Faculty of Applied Sciences, UiTM, Shah Alam, Selangor (Malaysia); Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin [Pusat Penyelidikan Mineral, Jabatan Mineral dan Geosains, Ipoh, Perak (Malaysia)

    2016-01-22

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite.

  16. Moldable cork ablation material

    Science.gov (United States)

    1977-01-01

    A successful thermal ablative material was manufactured. Moldable cork sheets were tested for density, tensile strength, tensile elongation, thermal conductivity, compression set, and specific heat. A moldable cork sheet, therefore, was established as a realistic product.

  17. Quantum coherent switch utilizing commensurate nanoelectrode and charge density periodicities

    Science.gov (United States)

    Harrison, Neil; Singleton, John; Migliori, Albert

    2008-08-05

    A quantum coherent switch having a substrate formed from a density wave (DW) material capable of having a periodic electron density modulation or spin density modulation, a dielectric layer formed onto a surface of the substrate that is orthogonal to an intrinsic wave vector of the DW material; and structure for applying an external spatially periodic electrostatic potential over the dielectric layer.

  18. Density controlled carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng F [Newton, MA; Tu, Yi [Belmont, MA

    2008-12-16

    CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

  19. Density of very small meteoroids

    Science.gov (United States)

    Kikwaya Eluo, Jean-Baptiste

    2015-08-01

    chondritic-like bulk densities, suggesting either the sintering of the meteoroids through evolutionary processes, or the original radial transportation of chondritic materials up to the Kuiper Belt region.

  20. Laboratory Density Functionals

    OpenAIRE

    Giraud, B. G.

    2007-01-01

    We compare several definitions of the density of a self-bound system, such as a nucleus, in relation with its center-of-mass zero-point motion. A trivial deconvolution relates the internal density to the density defined in the laboratory frame. This result is useful for the practical definition of density functionals.

  1. Laboratory Density Functionals

    OpenAIRE

    Giraud, B G

    2007-01-01

    We compare several definitions of the density of a self-bound system, such as a nucleus, in relation with its center-of-mass zero-point motion. A trivial deconvolution relates the internal density to the density defined in the laboratory frame. This result is useful for the practical definition of density functionals.

  2. Measurement of Power Density in a Lossy Material by means of Electromagnetically induced acoustic signals for non-invasive determination of spatial thermal absorption in connection with pulsed hyperthermia

    CERN Document Server

    Caspers, Friedhelm

    1982-01-01

    For non-invasive determination of the spatial power density distribution during RF- and microwave hyperthermia it is proposed to apply the electromagnetic energy as short, high intensity pulses. This pulsed signal should have the same average power and thus give the same temperature elevation as the CW source usually applied. Due to the high peak power of the equivalent pulsed signal, with a duty cycle < 1:100, externally measurable thermoacoustic oscillations are induced in the irradiated object. They can be evaluated for the reconstruction of a spatial power density profile.

  3. High energy density aluminum battery

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  4. High energy density aluminum battery

    Science.gov (United States)

    Brown, Gilbert M.; Paranthaman, Mariappan Parans; Dai, Sheng; Dudney, Nancy J.; Manthiram, Arumugan; McIntyre, Timothy J.; Sun, Xiao-Guang; Liu, Hansan

    2016-10-11

    Compositions and methods of making are provided for a high energy density aluminum battery. The battery comprises an anode comprising aluminum metal. The battery further comprises a cathode comprising a material capable of intercalating aluminum or lithium ions during a discharge cycle and deintercalating the aluminum or lithium ions during a charge cycle. The battery further comprises an electrolyte capable of supporting reversible deposition and stripping of aluminum at the anode, and reversible intercalation and deintercalation of aluminum or lithium at the cathode.

  5. Graded Density Carbon Bonded Carbon Fiber (CBCF) Preforms for Lightweight Ablative Thermal Protection Systems (TPS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — FMI has developed graded density CBCF preforms for graded density phenolic impregnated carbon ablator (PICA) material to meet NASA's future exploration mission...

  6. Theoretical studies on the heats of formation, detonation properties, and pyrolysis mechanisms of energetic cyclic nitramines.

    Science.gov (United States)

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

    2011-12-01

    Density functional theory calculations were performed to find comprehensive relationships between the structures and performance of a series of highly energetic cyclic nitramines. The isodesmic reaction method was employed to estimate the heat of formation. The detonation properties were evaluated by using the Kamlet-Jacobs equations based on the theoretical densities and HOFs. Results indicate the N-NO(2) group and aza N atom are effective substituents for enhancing the detonation performance. All cyclic nitramines except C11 and C21 exhibit better detonation performance than HMX. The decomposition mechanism and thermal stability of these cyclic nitramines were analyzed via the bond dissociation energies. For most of these nitramines, the homolysis of N-NO(2) is the initial step in the thermolysis, and the species with the bridged N-N bond are more sensitive than others. Considering the detonation performance and thermal stability, twelve derivatives may be the promising candidates of high energy density materials (HEDMs). The results of this study may provide basic information for the further study of this kind of compounds and molecular design of novel HEDMs.

  7. Contrast Materials

    Science.gov (United States)

    ... Physician Resources Professions Site Index A-Z Contrast Materials What are contrast materials and how do they ... material? Pregnancy and contrast materials What are contrast materials and how do they work? Contrast materials, also ...

  8. CHARACTERIZATION OF DAMAGED MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P C; Dehaven, M; McClelland, M; Chidester, S; Maienschein, J L

    2006-06-23

    Thermal damage experiments were conducted on LX-04, LX-10, and LX-17 at high temperatures. Both pristine and damaged samples were characterized for their material properties. A pycnometer was used to determine sample true density and porosity. Gas permeability was measured in a newly procured system (diffusion permeameter). Burn rate was measured in the LLNL strand burner. Weight losses upon thermal exposure were insignificant. Damaged pressed parts expanded, resulting in a reduction of bulk density by up to 10%. Both gas permeabilities and burn rates of the damaged samples increased by several orders of magnitude due to higher porosity and lower density. Moduli of the damaged materials decreased significantly, an indication that the materials became weaker mechanically. Damaged materials were more sensitive to shock initiation at high temperatures. No significant sensitization was observed when the damaged samples were tested at room temperature.

  9. Material Properies of Intermediate Materials between Concrete and Gravelly Soil

    Science.gov (United States)

    Uchimura, Taro; Kuramochi, Yuko; Thai, Bach Thuan

    Compaction and strength properties of cement-mixed well-graded gravel are studied. Such materials can also be considered as a kind of concrete materials which has much lower cement contents than usual. New concepts on material properties related to their mixture ratio of cement, gravel (aggregate) and water, as well as their compaction density, are proposed, unifying the concepts of geotechnical engineering and concrete engineering. For materials with higher cement contents, the compaction curve becomes flat, with lower maximum compaction density, and higher optimum water contents. The triaxial compressive strength are clearly affected by the dry density, as well as the cement contents.

  10. Future Road Density

    Data.gov (United States)

    U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...

  11. Crowding and Density

    Science.gov (United States)

    Design and Environment, 1972

    1972-01-01

    Three-part report pinpointing problems and uncovering solutions for the dual concepts of density (ratio of people to space) and crowding (psychological response to density). Section one, A Primer on Crowding,'' reviews new psychological and social findings; section two, Density in the Suburbs,'' shows conflict between status quo and increased…

  12. Assay Method for 235U in Low-Density Waste

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>235U assay method will provide a semi-quantitative assay for any uranium lumps that might exist in low-density, low-Z material waste boxes within a short count time. These materials will consist of

  13. Development of small-bore, high-current-density railgun as testbed for study of plasma-materials interaction. Progress report for October 16,2000 - May 13, 2003

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyekyoon [Kevin

    2003-05-14

    The present document is a final technical report summarizing the progress made during 10/16/2000 - 05/13/2003 toward the development of a small-bore railgun with transaugmentation as a testbed for investigating plasma-materials interaction.

  14. High Tap Density Spherical Li[Ni0.5Mn0.3Co0.2]O2 Cathode Material Synthesized via Continuous Hydroxide Coprecipitation Method for Advanced Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Shunyi Yang

    2012-01-01

    Full Text Available Spherical [Ni0.5Mn0.3Co0.2](OH2 precursor with narrow size distribution and high tap density has been successfully synthesized by a continuous hydroxide coprecipitation, and Li[Ni0.5Mn0.3Co0.2]O2 is then prepared by mixing the precursor with 6% excess Li2CO3 followed by calcinations. The tap density of the obtained Li[Ni0.5Mn0.3Co0.2]O2 powder is as high as 2.61 g cm−3. The powders are characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, scanning electron microscope (SEM, particle size distribution (PSD, and charge/discharge cycling. The XRD studies show that the prepared Li[Ni0.5Mn0.3Co0.2]O2 has a well-ordered layered structure without any impurity phases. Good packing properties of spherical secondary particles (about 12 μm consisted of a large number of tiny-thin plate-shape primary particles (less than 1 μm, which can be identified from the SEM observations. In the voltage range of 3.0–4.3 V and 2.5–4.6 V, Li[Ni0.5Mn0.3Co0.2]O2 delivers the initial discharge capacity of approximately 175 and 214 mAh g−1 at a current density of 32 mA g−1, and the capacity retention after 50 cycles reaches 98.8% and 90.2%, respectively. Besides, it displays good high-temperature characteristics and excellent rate capability.

  15. Development of optimum process for electron beam cross-linking of high density polyethylene thermal energy storage pellets, process scale-up and production of application qualities of material

    Science.gov (United States)

    Salyer, I. O.

    1980-01-01

    The electron irradiation conditions required to prepare thermally from stable high density polyethylene (HDPE) were defined. The conditions were defined by evaluating the heat of fusion and the melting temperature of several HDPE specimens. The performance tests conducted on the specimens, including the thermal cycling tests in the thermal energy storage unit are described. The electron beam irradiation tests performed on the specimens, in which the total radiation dose received by the pellets, the electron beam current, the accelerating potential, and the atmospheres were varied, are discussed.

  16. Architected Cellular Materials

    Science.gov (United States)

    Schaedler, Tobias A.; Carter, William B.

    2016-07-01

    Additive manufacturing enables fabrication of materials with intricate cellular architecture, whereby progress in 3D printing techniques is increasing the possible configurations of voids and solids ad infinitum. Examples are microlattices with graded porosity and truss structures optimized for specific loading conditions. The cellular architecture determines the mechanical properties and density of these materials and can influence a wide range of other properties, e.g., acoustic, thermal, and biological properties. By combining optimized cellular architectures with high-performance metals and ceramics, several lightweight materials that exhibit strength and stiffness previously unachievable at low densities were recently demonstrated. This review introduces the field of architected materials; summarizes the most common fabrication methods, with an emphasis on additive manufacturing; and discusses recent progress in the development of architected materials. The review also discusses important applications, including lightweight structures, energy absorption, metamaterials, thermal management, and bioscaffolds.

  17. Probability densities and Lévy densities

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler

    For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated.......For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated....

  18. Probability densities and Lévy densities

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler

    For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated.......For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated....

  19. Method to reduce dislocation density in silicon using stress

    Science.gov (United States)

    Buonassisi, Anthony; Bertoni, Mariana; Argon, Ali; Castellanos, Sergio; Fecych, Alexandria; Powell, Douglas; Vogl, Michelle

    2013-03-05

    A crystalline material structure with reduced dislocation density and method of producing same is provided. The crystalline material structure is annealed at temperatures above the brittle-to-ductile transition temperature of the crystalline material structure. One or more stress elements are formed on the crystalline material structure so as to annihilate dislocations or to move them into less harmful locations.

  20. High density fluoride glass calorimeter

    Science.gov (United States)

    Xie, Q.; Scheltzbaum, J.; Akgun, U.

    2014-04-01

    The unprecedented radiation levels in current Large Hadron Collider runs, and plans to even increase the luminosity creates a need for new detector technologies to be investigated. Quartz plates to replace the plastic scintillators in current LHC calorimeters have been proposed in recent reports. Quartz based Cherenkov calorimeters can solve the radiation damage problem, however light production and transfer have proven to be challenging. This report summarizes the results from a computational study on the performance of a high-density glass calorimeter. High-density, scintillating, fluoride glass, CHG3, was used as the active material. This glass has been developed specifically for hadron collider experiments, and is known for fast response time, in addition to high light yield. Here, the details of a Geant4 model for a sampling calorimeter prototype with 20 layers, and its hadronic as well as electromagnetic performances are reported.

  1. Sorting cells by their density

    Science.gov (United States)

    Norouzi, Nazila; Bhakta, Heran C.

    2017-01-01

    Sorting cells by their type is an important capability in biological research and medical diagnostics. However, most cell sorting techniques rely on labels or tags, which may have limited availability and specificity. Sorting different cell types by their different physical properties is an attractive alternative to labels because all cells intrinsically have these physical properties. But some physical properties, like cell size, vary significantly from cell to cell within a cell type; this makes it difficult to identify and sort cells based on their sizes alone. In this work we continuously sort different cells types by their density, a physical property with much lower cell-to-cell variation within a cell type (and therefore greater potential to discriminate different cell types) than other physical properties. We accomplish this using a 3D-printed microfluidic chip containing a horizontal flowing micron-scale density gradient. As cells flow through the chip, Earth’s gravity makes each cell move vertically to the point where the cell’s density matches the surrounding fluid’s density. When the horizontal channel then splits, cells with different densities are routed to different outlets. As a proof of concept, we use our density sorter chip to sort polymer microbeads by their material (polyethylene and polystyrene) and blood cells by their type (white blood cells and red blood cells). The chip enriches the fraction of white blood cells in a blood sample from 0.1% (in whole blood) to nearly 98% (in the output of the chip), a 1000x enrichment. Any researcher with access to a 3D printer can easily replicate our density sorter chip and use it in their own research using the design files provided as online Supporting Information. Additionally, researchers can simulate the performance of a density sorter chip in their own applications using the Python-based simulation software that accompanies this work. The simplicity, resolution, and throughput of this

  2. Population Density Modeling Tool

    Science.gov (United States)

    2014-02-05

    194 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke 26 June 2012 Distribution...MARYLAND NAWCADPAX/TR-2012/194 26 June 2012 POPULATION DENSITY MODELING TOOL by Davy Andrew Michael Knott David Burke...Density Modeling Tool 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Davy Andrew Michael Knott David Burke 5d. PROJECT NUMBER

  3. Modelling of thermoelectric materials

    DEFF Research Database (Denmark)

    Bjerg, Lasse

    In order to discover new good thermoelectric materials, there are essentially two ways. One way is to go to the laboratory, synthesise a new material, and measure the thermoelectric properties. The amount of compounds, which can be investigated this way is limited because the process is time...... consuming. Another approach is to model the thermoelectric properties of a material on a computer. Several crystal structures can be investigated this way without use of much man power. I have chosen the latter approach. Using density functional theory I am able to calculate the band structure of a material....... This band structure I can then use to calculate the thermoelectric properties of the material. With these results I have investigated several materials and found the optimum theoretical doping concentration. If materials with these doping concentrations be synthesised, considerably better thermoelectric...

  4. Isogeometric shape optimization of magnetic density separators

    OpenAIRE

    2013-01-01

    Purpose: The waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently a new separator design that significantly reduces the required amount of permanent magnet material has been proposed. The purpose of this paper is to alleviate the undesired end-effects in this design by altering the shape of the ferromagnetic covers of the...

  5. Materials for hydrogen storage

    Directory of Open Access Journals (Sweden)

    Andreas Züttel

    2003-09-01

    The goal is to pack hydrogen as close as possible, i.e. to reach the highest volumetric density by using as little additional material as possible. Hydrogen storage implies the reduction of an enormous volume of hydrogen gas. At ambient temperature and atmospheric pressure, 1 kg of the gas has a volume of 11 m3. To increase hydrogen density, work must either be applied to compress the gas, the temperature decreased below the critical temperature, or the repulsion reduced by the interaction of hydrogen with another material.

  6. Porous Thermoelectric Materials

    Directory of Open Access Journals (Sweden)

    Hiroshi Julian Goldsmid

    2009-08-01

    Full Text Available Thermoelectric materials are sometimes prepared using a sintering process in which the achievement of a high density is often one of the objectives. However, it has recently been shown that the introduction of a highly porous material is desirable in synthetic transverse thermoelements. Porosity may also be an advantage in conventional longitudinal thermoelectric modules in which a high thermal flux density creates problems, but heat transfer within the pores can degrade the thermoelectric figure of merit. The amount of this degradation is calculated and it is shown that it can be small enough to be acceptable in practical devices.

  7. Density dependent neurodynamics.

    Science.gov (United States)

    Halnes, Geir; Liljenström, Hans; Arhem, Peter

    2007-01-01

    The dynamics of a neural network depends on density parameters at (at least) two different levels: the subcellular density of ion channels in single neurons, and the density of cells and synapses at a network level. For the Frankenhaeuser-Huxley (FH) neural model, the density of sodium (Na) and potassium (K) channels determines the behaviour of a single neuron when exposed to an external stimulus. The features of the onset of single neuron oscillations vary qualitatively among different regions in the channel density plane. At a network level, the density of neurons is reflected in the global connectivity. We study the relation between the two density levels in a network of oscillatory FH neurons, by qualitatively distinguishing between three regions, where the mean network activity is (1) spiking, (2) oscillating with enveloped frequencies, and (3) bursting, respectively. We demonstrate that the global activity can be shifted between regions by changing either the density of ion channels at the subcellular level, or the connectivity at the network level, suggesting that different underlying mechanisms can explain similar global phenomena. Finally, we model a possible effect of anaesthesia by blocking specific inhibitory ion channels.

  8. On density forecast evaluation

    NARCIS (Netherlands)

    Diks, C.

    2008-01-01

    Traditionally, probability integral transforms (PITs) have been popular means for evaluating density forecasts. For an ideal density forecast, the PITs should be uniformly distributed on the unit interval and independent. However, this is only a necessary condition, and not a sufficient one, as

  9. MEASUREMENT OF WHEAT DENSITY

    Institute of Scientific and Technical Information of China (English)

    冯跟胜; 党金春; 等

    1995-01-01

    A method used for on line determining the change of wheat density with a automatic watering machine in a lqarge flour mill has been studied.The results show that the higher distinguishing ability is obtained when using 241Am as a γ-ray source for measuring the wheat density than using 137Cs.

  10. Learning Grasp Affordance Densities

    DEFF Research Database (Denmark)

    Detry, Renaud; Kraft, Dirk; Kroemer, Oliver

    2011-01-01

    We address the issue of learning and representing object grasp affordance models. We model grasp affordances with continuous probability density functions (grasp densities) which link object-relative grasp poses to their success probability. The underlying function representation is nonparametric...... and relies on kernel density estimation to provide a continuous model. Grasp densities are learned and refined from exploration, by letting a robot “play” with an object in a sequence of graspand-drop actions: The robot uses visual cues to generate a set of grasp hypotheses; it then executes...... these and records their outcomes. When a satisfactory number of grasp data is available, an importance-sampling algorithm turns these into a grasp density. We evaluate our method in a largely autonomous learning experiment run on three objects of distinct shapes. The experiment shows how learning increases success...

  11. Symmetry energy and density

    CERN Document Server

    Trautmann, Wolfgang; Russotto, Paolo

    2016-01-01

    The nuclear equation-of-state is a topic of highest current interest in nuclear structure and reactions as well as in astrophysics. In particular, the equation-of-state of asymmetric matter and the symmetry energy representing the difference between the energy densities of neutron matter and of symmetric nuclear matter are not sufficiently well constrained at present. The density dependence of the symmetry energy is conventionally expressed in the form of the slope parameter L describing the derivative with respect to density of the symmetry energy at saturation. Results deduced from nuclear structure and heavy-ion reaction data are distributed around a mean value L=60 MeV. Recent studies have more thoroughly investigated the density range that a particular observable is predominantly sensitive to. Two thirds of the saturation density is a value typical for the information contained in nuclear-structure data. Higher values exceeding saturation have been shown to be probed with meson production and collective ...

  12. High current density cathode for electrorefining in molten electrolyte

    Science.gov (United States)

    Li, Shelly X.

    2010-06-29

    A high current density cathode for electrorefining in a molten electrolyte for the continuous production and collection of loose dendritic or powdery deposits. The high current density cathode eliminates the requirement for mechanical scraping and electrochemical stripping of the deposits from the cathode in an anode/cathode module. The high current density cathode comprises a perforated electrical insulated material coating such that the current density is up to 3 A/cm.sup.2.

  13. Modified Low Density Polyethylene by Nano-fills as Insulating Material of DC Cable (Ⅱ)%纳米粒子改性聚乙烯直流电缆绝缘材料研究(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    吴锴; 陈曦; 王霞; 成永红; 屠德民

    2013-01-01

    在电缆聚乙烯材料中添加一种新型纳米粒子可以有效改善材料中的空间电荷积聚,提高其直流击穿强度和体积电阻率.为深入了解此纳米粒子作用机理,基于电声脉冲法(PEA)和充电-放电电流法,分别测量了在不同温度下、不同纳米含量时聚乙烯纳米复合材料的极化/去极化特性.用PEA方法得到不同温度下材料的平均电荷体密度、视在迁移率和陷阱深度,结果表明,20~40℃下,纯聚乙烯及聚乙烯纳米复合材料试样内的陷阱以浅陷阱分布为主;80℃下,当聚乙烯中纳米粒子质量分数>3%时,会增加复合材料陷阱深度.用充电-放电电流法计算得到材料的迁移率,可知在20~60℃内,不同试样迁移率的变化主要由纳米粒子和温度共同作用产生,而在60~80℃内,迁移率的变化则是温度起主要作用.分析认为,电荷输运受到陷阱与温度的影响是导致电阻率变化的主要原因,而在温度梯度场下,聚乙烯纳米复合材料电阻率的正温度系数趋势是抑制材料内空间电荷积聚的主要原因.%Adding a novel nano filler in the insulation of high voltage direct current (HVDC) cable is proved to be capable of restricting space charge accumulation, and enhancing DC breakdown strength and volume resistivity of the low density polyethylene (LDPE). In order to further study the working mechanism of the nano filler, the polarization and depolarization characteristics of pure LDPE and LDPE nanocomposites with different nano fillers under different temperatures were tested based on the pulsed electro-acoustic ( PEA) method and charging / discharging current method, respectively. Parameters, including the mean volume density of space charge, apparent trap-controlled mobility and trap depth distribution, were achieved by the PEA method: shallow traps were dominant in pure LDPE and LDPE nanocomposites under 20~40 ℃; the trap depth increased under 80 ℃ in

  14. Intrinsic-Density Functionals

    CERN Document Server

    Engel, J

    2006-01-01

    The Hohenberg-Kohn theorem and Kohn-Sham procedure are extended to functionals of the localized intrinsic density of a self-bound system such as a nucleus. After defining the intrinsic-density functional, we modify the usual Kohn-Sham procedure slightly to evaluate the mean-field approximation to the functional, and carefully describe the construction of the leading corrections for a system of fermions in one dimension with a spin-degeneracy equal to the number of particles N. Despite the fact that the corrections are complicated and nonlocal, we are able to construct a local Skyrme-like intrinsic-density functional that, while different from the exact functional, shares with it a minimum value equal to the exact ground-state energy at the exact ground-state intrinsic density, to next-to-leading order in 1/N. We briefly discuss implications for real Skyrme functionals.

  15. Bone mineral density test

    Science.gov (United States)

    BMD test; Bone density test; Bone densitometry; DEXA scan; DXA; Dual-energy x-ray absorptiometry; p-DEXA; Osteoporosis-BMD ... need to undress. This scan is the best test to predict your risk of fractures. Peripheral DEXA ( ...

  16. The local mass density

    Science.gov (United States)

    Veeder, G. J.

    1974-01-01

    An improved mass-luminosity relation for faint main-sequence stars derived from recently revised masses for some faint double stars is presented. The total local mass density is increased to nearly 0.2 solar masses per cu pc. This estimate is as large as the mass density required by Oort's (1965) dynamical analysis of stellar motions perpendicular to the galactic plane if the mass is concentrated in a narrow layer.

  17. Advanced Aircraft Material

    Directory of Open Access Journals (Sweden)

    Vivek Kumar Prince

    2013-06-01

    Full Text Available There has been long debate on “advanced aircraft material” from past decades & researchers too came out with lots of new advanced material like composites and different aluminum alloys. Now days a new advancement that is in great talk is third generation Aluminum-lithium alloy. Newest Aluminum-lithium alloys are found out to have low density, higher elastic modulus, greater stiffness, greater cryogenic toughness, high resistance to fatigue cracking and improved corrosion resistance properties over the earlier used aircraft material as mentioned in Table 3 [1-5]. Comparison had been made with nowadays used composite material and is found out to be more superior then that

  18. Electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Amine, Khalil; Abouimrane, Ali; Belharouak, Ilias

    2017-01-31

    A process for forming a surface-treatment layer on an electroactive material includes heating the electroactive material and exposing the electroactive material to a reducing gas to form a surface-treatment layer on the electroactive material, where the surface-treatment layer is a layer of partial reduction of the electroactive material.

  19. Materials research for fusion

    Science.gov (United States)

    Knaster, J.; Moeslang, A.; Muroga, T.

    2016-05-01

    Fusion materials research started in the early 1970s following the observation of the degradation of irradiated materials used in the first commercial fission reactors. The technological challenges of fusion energy are intimately linked with the availability of suitable materials capable of reliably withstanding the extremely severe operational conditions of fusion reactors. Although fission and fusion materials exhibit common features, fusion materials research is broader. The harder mono-energetic spectrum associated with the deuterium-tritium fusion neutrons (14.1 MeV compared to hydrogen and helium as transmutation products that might lead to a (at present undetermined) degradation of structural materials after a few years of operation. Overcoming the historical lack of a fusion-relevant neutron source for materials testing is an essential pending step in fusion roadmaps. Structural materials development, together with research on functional materials capable of sustaining unprecedented power densities during plasma operation in a fusion reactor, have been the subject of decades of worldwide research efforts underpinning the present maturity of the fusion materials research programme.

  20. Relativistic density functional for nuclear structure

    CERN Document Server

    2016-01-01

    This book aims to provide a detailed introduction to the state-of-the-art covariant density functional theory, which follows the Lorentz invariance from the very beginning and is able to describe nuclear many-body quantum systems microscopically and self-consistently. Covariant density functional theory was introduced in nuclear physics in the 1970s and has since been developed and used to describe the diversity of nuclear properties and phenomena with great success. In order to provide an advanced and updated textbook of covariant density functional theory for graduate students and nuclear physics researchers, this book summarizes the enormous amount of material that has accumulated in the field of covariant density functional theory over the last few decades as well as the latest developments in this area. Moreover, the book contains enough details for readers to follow the formalism and theoretical results, and provides exhaustive references to explore the research literature.

  1. High Density Matter

    Directory of Open Access Journals (Sweden)

    Stone J.R.

    2013-12-01

    Full Text Available The microscopic composition and properties of matter at super-saturation densities have been the subject of intense investigation for decades. The scarcity of experimental and observational data has led to the necessary reliance on theoretical models. There remains great uncertainty in these models which, of necessity, have to go beyond the over-simple assumption that high density matter consists only of nucleons and leptons. Heavy strange baryons, mesons and quark matter in different forms and phases have to be included to fulfil basic requirements of fundamental laws of physics. In this contribution latest developments in construction of the Equation of State (EoS of high-density matter at zero and finite temperature assuming different composition of matter will be discussed. Critical comparison of model EoS with available experimental data from heavy ion collisions and observations on neutron stars, including gravitational mass, radii and cooling patterns and data on X-ray burst sources and low mass X-ray binaries are made. Fundamental differences between the EoS of low-density, high temperature matter, such as is created in heavy ion collisions and of high-density, low temperature compact objects is discussed.

  2. Correlation of Critical Current Density with Cu3+ Concentration and Density in YBa2Cu3O7-x

    Science.gov (United States)

    Dou, S. X.; Liu, H. K.; Zhou, J. P.; Bourdillon, A. J.; Savvides, N.; Apperley, M.; Gouch, A.; Sorrell, C. C.

    Superconducting YBa2Cu3O7 wires and tapes were fabricated by cold drawing, rolling and extrusion processes. It was found that the critical current density, after O2 equilibration, correlates both with density and Cu3+ concentration. Full density was achieved by using a special heat treatment, but the critical current density was low owing to the low Cu3+ concentration present in this heavily twinned material. The best critical current density results were obtained for material with density of 92-95% of the theoretical value. The low critical current density of the porous specimens is attributed not only to a poor connectivity between grains but also to a low Cu3+ concentration due to the instability of Cu3+ at crystallite surfaces which increase in area with specimen porosity.

  3. Density and morphology adjustments of gallium nitride nanowires

    Science.gov (United States)

    Teker, Kasif

    2013-10-01

    This paper presents the morphology and density adjustments of GaN nanostructures via CVD process. GaN nanostructure growth has been carried out using Ga and NH3 as source materials with various catalyst materials, such as Au, Ni, Ag, and Fe between 800 and 1100 °C. The investigation has focused on the effects of process parameters, such as growth temperature and catalyst materials on the GaN nanowire morphology and density. Low temperature (contamination and produces high density of long nanowires, which is very crucial for scale-up manufacturing opportunities.

  4. Bone density and its importance in orthodontics

    Science.gov (United States)

    Chugh, Tina; Jain, Abhay Kumar; Jaiswal, Raj Kumar; Mehrotra, Praveen; Mehrotra, Rachita

    2013-01-01

    Background Researchers have generally focused on tissue reactions occurring within the periodontal ligament and bone to find possible explanation for various clinical phenomena, with less attention being paid to the inherent bone density. Recently, regional differences in jaw anatomy and bone structure including bone density have become important issue to explain some of the variation in clinical practice with respect to tooth movement, implant success rate, anchorage loss etc. Materials and methods The intent of this review is to discuss various methods and classification proposed to determine bone density in particular area and its importance in field of orthodontia. Various clinical studies and research done in relation to bone density were searched using PubMed. Results and conclusion This review endeavours to compile the research of bone density in maxilla and mandible. Many clinical studies have demonstrated relation between bone density and various clinical phenomena in dentistry. Knowledge of bone density in particular area of oral cavity may help the clinician to plan proper site for implant placement and various anchorage augmentation techniques in order to increase success rate of the treatment. PMID:25737892

  5. Nuclear level density predictions

    Directory of Open Access Journals (Sweden)

    Bucurescu Dorel

    2015-01-01

    Full Text Available Simple formulas depending only on nuclear masses were previously proposed for the parameters of the Back-Shifted Fermi Gas (BSFG model and of the Constant Temperature (CT model of the nuclear level density, respectively. They are now applied for the prediction of the level density parameters of all nuclei with available masses. Both masses from the new 2012 mass table and from different models are considered and the predictions are discussed in connection with nuclear regions most affected by shell corrections and nuclear structure effects and relevant for the nucleosynthesis.

  6. Density Distribution Sunflower Plots

    OpenAIRE

    Dupont, William D; W. Dale Plummer Jr.

    2003-01-01

    Density distribution sunflower plots are used to display high-density bivariate data. They are useful for data where a conventional scatter plot is difficult to read due to overstriking of the plot symbol. The x-y plane is subdivided into a lattice of regular hexagonal bins of width w specified by the user. The user also specifies the values of l, d, and k that affect the plot as follows. Individual observations are plotted when there are less than l observations per bin as in a conventio...

  7. Holographic Magnetisation Density Waves

    CERN Document Server

    Donos, Aristomenis

    2016-01-01

    We numerically construct asymptotically $AdS$ black brane solutions of $D=4$ Einstein theory coupled to a scalar and two $U(1)$ gauge fields. The solutions are holographically dual to $d=3$ CFTs in a constant external magnetic field along one of the $U(1)$'s. Below a critical temperature the system's magnetisation density becomes inhomogeneous, leading to spontaneous formation of current density waves. We find that the transition can be of second order and that the solutions which minimise the free energy locally in the parameter space of solutions have averaged stressed tensor of a perfect fluid.

  8. Polarizable Density Embedding

    DEFF Research Database (Denmark)

    Olsen, Jógvan Magnus Haugaard; Steinmann, Casper; Ruud, Kenneth

    2015-01-01

    We present a new QM/QM/MM-based model for calculating molecular properties and excited states of solute-solvent systems. We denote this new approach the polarizable density embedding (PDE) model and it represents an extension of our previously developed polarizable embedding (PE) strategy. The PDE...... model is a focused computational approach in which a core region of the system studied is represented by a quantum-chemical method, whereas the environment is divided into two other regions: an inner and an outer region. Molecules belonging to the inner region are described by their exact densities...

  9. Holographic charge density waves

    CERN Document Server

    Donos, Aristomenis

    2013-01-01

    We show that strongly coupled holographic matter at finite charge density can exhibit charge density wave phases which spontaneously break translation invariance while preserving time-reversal and parity invariance. We show that such phases are possible within Einstein-Maxwell-dilaton theory in general spacetime dimensions. We also discuss related spatially modulated phases when there is an additional coupling to a second vector field, possibly with non-zero mass. We discuss how these constructions, and others, should be associated with novel spatially modulated ground states.

  10. Holographic charge density waves

    Science.gov (United States)

    Donos, Aristomenis; Gauntlett, Jerome P.

    2013-06-01

    We show that strongly coupled holographic matter at finite charge density can exhibit charge density wave phases which spontaneously break translation invariance while preserving time-reversal and parity invariance. We show that such phases are possible within Einstein-Maxwell-dilaton theory in general spacetime dimensions. We also discuss related spatially modulated phases when there is an additional coupling to a second vector field, possibly with nonzero mass. We discuss how these constructions, and others, should be associated with novel spatially modulated ground states.

  11. Density matrix perturbation theory.

    Science.gov (United States)

    Niklasson, Anders M N; Challacombe, Matt

    2004-05-14

    An orbital-free quantum perturbation theory is proposed. It gives the response of the density matrix upon variation of the Hamiltonian by quadratically convergent recursions based on perturbed projections. The technique allows treatment of embedded quantum subsystems with a computational cost scaling linearly with the size of the perturbed region, O(N(pert.)), and as O(1) with the total system size. The method allows efficient high order perturbation expansions, as demonstrated with an example involving a 10th order expansion. Density matrix analogs of Wigner's 2n+1 rule are also presented.

  12. Gap and density theorems

    CERN Document Server

    Levinson, N

    1940-01-01

    A typical gap theorem of the type discussed in the book deals with a set of exponential functions { \\{e^{{{i\\lambda}_n} x}\\} } on an interval of the real line and explores the conditions under which this set generates the entire L_2 space on this interval. A typical gap theorem deals with functions f on the real line such that many Fourier coefficients of f vanish. The main goal of this book is to investigate relations between density and gap theorems and to study various cases where these theorems hold. The author also shows that density- and gap-type theorems are related to various propertie

  13. Building Materials

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Building Materials Sub-council of CCPIT is the other sub-council in construction field. CCPIT Building Materials Sub-council (CCPITBM), as well as CCOIC Build-ing Materials Chamber of Commerce, is au-thorized by CCPIT and state administration of building materials industry in 1992. CCPITBM is a sub-organization of CCPIT and CCOIC.

  14. Material Effectiveness for Radiation Shielding

    Science.gov (United States)

    2003-01-01

    Materials with a smaller mean atomic mass, such as lithium (Li) hydride and polyethylene, make the best radiation shields for astronauts. The materials have a higher density of nuclei and are better able to block incoming radiation. Also, they tend to produce fewer and less dangerous secondary particles after impact with incoming radiation.

  15. A novel graded density impactor

    Science.gov (United States)

    Winter, R. E.; Cotton, M.; Harris, E. J.; Chapman, D. J.; Eakins, D.

    2014-05-01

    Ramp loading using graded-density-impactors as flyers in gas-gun-driven plate impact experiments can yield new and useful information about the equation of state and the strength properties of the loaded material. Selective Laser Melting, an additive manufacture technique, was used to manufacture a graded density flyer, termed the "bed of nails" (BON). A 2 mm thick × 100 mm diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 6 mm and spaced 1 mm apart. The two experiments to test the concept were performed at impact velocities of 900 m/s and 1100 m/s using the 100 mm gas gun at the Institute of Shock Physics at Imperial College, London. In each experiment a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, which were mounted in contact with the back face of the copper. Heterodyne velocimetry was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in velocity over a period of ~2.5 us, with no indication of a shock jump. The measured profiles have been analysed to generate a stress strain curve for tantalum. The results have been compared with the predictions of the Sandia National Laboratories hydrocode, CTH.

  16. Energy in density gradient

    CERN Document Server

    Vranjes, J

    2015-01-01

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...

  17. Density of Gabor Frames

    DEFF Research Database (Denmark)

    Christensen, Ole; Heil, Christopher; Deng, Baiqiao

    1999-01-01

    Beurling densities of Lambda = boolean ORk=1r Lambda(k) satisfy D- (Lambda) greater than or equal to 1 and D+(Lambda) Ramanathan and Steger. Additionally, we prove the conjecture that no collection boolean ORk=1r {g(k)(x - a)}(a is an element of Gamma k) of pure...

  18. Energy in density gradient

    Energy Technology Data Exchange (ETDEWEB)

    Vranjes, J., E-mail: jvranjes@yahoo.com [Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife (Spain); Departamento de Astrofísica, Universidad de La Laguna, 38205 La Laguna, Tenerife (Spain); Kono, M., E-mail: kono@fps.chuo-u.ac.jp [Faculty of Policy Studies, Chuo University, Tokyo (Japan)

    2015-01-15

    Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work, the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindrical configuration. This is of practical importance for drift wave instability in various plasmas, and, in particular, in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit volume (per second) in quiet regions in the corona. Consequently, within the life-time of a magnetic structure such energy losses can easily be compensated by the stochastic drift wave heating.

  19. Culture systems: embryo density.

    Science.gov (United States)

    Reed, Michael L

    2012-01-01

    Embryo density is defined as the embryo-to-volume ratio achieved during in vitro culture; in other words, it is the number of embryos in a defined volume of culture medium. The same density can be achieved by manipulating either the number of embryos in a given volume of medium, or manipulating the volume of the medium for a given number of embryos: for example, a microdrop with five embryos in a 50 μl volume under oil has the same embryo-to-volume ratio (1:10 μl) as a microdrop with one embryo in a 10 μl volume under oil (1:10 μl). Increased embryo density can improve mammalian embryo development in vitro; however, the mechanism(s) responsible for this effect may be different with respect to which method is used to increase embryo density.Standard, flat sterile plastic petri dishes are the most common, traditional platform for embryo culture. Microdrops under a mineral oil overlay can be prepared to control embryo density, but it is critical that dish preparation is consistent, where appropriate techniques are applied to prevent microdrop dehydration during preparation, and results of any data collection are reliable, and repeatable. There are newer dishes available from several manufacturers that are specifically designed for embryo culture; most are readily available for use with human embryos. The concept behind these newer dishes relies on fabrication of conical and smaller volume wells into the dish design, so that embryos rest at the lowest point in the wells, and where putative embryotrophic factors may concentrate.Embryo density is not usually considered by the embryologist as a technique in and of itself; rather, the decision to culture embryos in groups or individually is protocol-driven, and is based more on convenience or the need to collect data on individual embryos. Embryo density can be controlled, and as such, it can be utilized as a simple, yet effective tool to improve in vitro development of human embryos.

  20. Materials Development

    Institute of Scientific and Technical Information of China (English)

    Brian Tomlinson

    2005-01-01

    @@ Introduction Materials development is both a field of study and a practical undertaking. As a field it studies the principles and procedures of the design, implementation and evaluation and adaptation of language teaching materials, by teachers for their own classrooms and by materials writers for sale or distribution. Ideally these two aspects of materials development are interactive in that the theoretical studies inform and are informed by the development and use of classroom materials (e. g. Tomlinson 1998c).

  1. Partition density functional theory

    Science.gov (United States)

    Nafziger, Jonathan

    Partition density functional theory (PDFT) is a method for dividing a molecular electronic structure calculation into fragment calculations. The molecular density and energy corresponding to Kohn Sham density-functional theory (KS-DFT) may be exactly recovered from these fragments. Each fragment acts as an isolated system except for the influence of a global one-body 'partition' potential which deforms the fragment densities. In this work, the developments of PDFT are put into the context of other fragment-based density functional methods. We developed three numerical implementations of PDFT: One within the NWChem computational chemistry package using basis sets, and the other two developed from scratch using real-space grids. It is shown that all three of these programs can exactly reproduce a KS-DFT calculation via fragment calculations. The first of our in-house codes handles non-interacting electrons in arbitrary one-dimensional potentials with any number of fragments. This code is used to explore how the exact partition potential changes for different partitionings of the same system and also to study features which determine which systems yield non-integer PDFT occupations and which systems are locked into integer PDFT occupations. The second in-house code, CADMium, performs real-space calculations of diatomic molecules. Features of the exact partition potential are studied for a variety of cases and an analytical formula determining singularities in the partition potential is derived. We introduce an approximation for the non-additive kinetic energy and show how this quantity can be computed exactly. Finally a PDFT functional is developed to address the issues of static correlation and delocalization errors in approximations within DFT. The functional is applied to the dissociation of H2 + and H2.

  2. Negative Plasma Densities Raise Questions

    Energy Technology Data Exchange (ETDEWEB)

    Hazi, A

    2006-01-26

    Nearly all the matter encountered on Earth is either a solid, liquid, or gas. Yet plasma-the fourth state of matter-comprises more than 99 percent of the visible universe. Understanding the physical characteristics of plasmas is important to many areas of scientific research, such as the development of fusion as a clean, renewable energy source. Lawrence Livermore scientists study the physics of plasmas in their pursuit to create fusion energy, because plasmas are an integral part of that process. When deuterium and tritium are heated to the extreme temperatures needed to achieve and sustain a fusion reaction (about 100 million degrees), the electrons in these light atoms become separated from the nuclei. This process of separation is called ionization, and the resulting collection of negatively charged free electrons and positively charged nuclei is known as a plasma. Although plasmas and gases have many similar properties, plasmas differ from gases in that they are good conductors of electricity and can generate magnetic fields. For the past decade, x-ray laser interferometry has been used in the laboratory for measuring a plasma's index of refraction to determine plasma density. (The index of refraction for a given material is defined as the wavelength of light in a vacuum divided by the wavelength of light traveling through the material.) Until now, plasma physicists expected to find an index of refraction less than one. Researchers from Livermore and Colorado State University recently conducted experiments on aluminum plasmas at the Laboratory's COMET laser facility and observed results in which the index of refraction was greater than one. This surprising result implied a negative electron density. Livermore physicist Joseph Nilsen and his colleagues from Livermore and the University of Notre Dame have performed sophisticated calculations to explain this phenomenon. Previously, researchers believed that only free electrons contributed to the index

  3. Materials Chemistry

    CERN Document Server

    Fahlman, Bradley D

    2011-01-01

    The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

  4. Precision measurements of Linear Scattering Density using Muon Tomography

    CERN Document Server

    Åström, E; Calliari, I; Calvini, P; Checchia, P; Donzella, A; Faraci, E; Forsberg, F; Gonella, F; Hu, X; Klinger, J; Ödqvist, L S; Pagano, D; Rigoni, A; Ramous, E; Urbani, M; Vanini, S; Zenoni, A; Zumerle, G

    2016-01-01

    We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.

  5. Precision measurements of linear scattering density using muon tomography

    Science.gov (United States)

    Åström, E.; Bonomi, G.; Calliari, I.; Calvini, P.; Checchia, P.; Donzella, A.; Faraci, E.; Forsberg, F.; Gonella, F.; Hu, X.; Klinger, J.; Sundqvist Ökvist, L.; Pagano, D.; Rigoni, A.; Ramous, E.; Urbani, M.; Vanini, S.; Zenoni, A.; Zumerle, G.

    2016-07-01

    We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.

  6. Percolation and Low Density Materials: Theory and Applications

    Science.gov (United States)

    1990-06-01

    the critical point (Heermann et al 1983). E. Literature Cited Alexander S and Orbach R 1983 J Phys (Paris) 43 L625 Amitrano C, di Liberto F, Figari R...s-state Potts and n-vector models at the percolation threshold" Phys. Rev. Lett. 46, 250-3 (1981). *45. A. Coniglio, F. di Liberto and G. Monroy...1982). *81. A. Coniglio, F. di Liberto , G. Monroy and F. Peruggi, "Clusters and Ising droplets in the antiferromag- netic lattice gas" Phys. Lett. 87A

  7. Synthesis of Novel High Energy Density Materials Using Nitrocarbenes

    Science.gov (United States)

    1992-02-21

    synthesis is our finding that the combination of titanium tetrachloride/methylene bromide/zinc smoothly converts the caged diketone to the bismethylene...AD-A248 465 AO PAGE ft 07ŕ Februa re 21 , 992uq" Final~o Repotm 8//9 -12319 4. TITLE AND SUBTITLE S. FUNOING NUMBERS Synthesis of Novel High Energy...theory to predict the structures and energies of potential energetic molecules and to guide the synthesis of the more promising candidate molecules, 2

  8. Carbon Nanotube Spaceframes for Low-Density Aerospace Materials

    Science.gov (United States)

    2012-01-26

    carbene grafting followed by SN2 amination • Amine linking reactions 3 L. Jiang & L. Gao...reactively linked to the target CNT surface moiety via a reversible reaction (e.g. esterification). Remaining dye is thoroughly removed by rinsing and...solvolysis type reactions to bind and cleave the dye from the nanotube surface. Aminoazotoluene is an effective assay dye to characterize carboxylic

  9. The Search for New High-Energy-Density Materials

    Science.gov (United States)

    2014-01-01

    a Mn atom with halogen atoms and stability of its half-filled 3d- shell ”, J. Chem. Phys. 134, 234311 (2011) Pathak, B., Samanta, D., Ahuja, R...Society, Cocoa Beach, FL, February 21-25, 2010 US-Egypt Advanced Studies Institute (ASI) on “Nanomaterials and Nanocatalysis for Energy

  10. Strongly correlated materials.

    Science.gov (United States)

    Morosan, Emilia; Natelson, Douglas; Nevidomskyy, Andriy H; Si, Qimiao

    2012-09-18

    Strongly correlated materials are profoundly affected by the repulsive electron-electron interaction. This stands in contrast to many commonly used materials such as silicon and aluminum, whose properties are comparatively unaffected by the Coulomb repulsion. Correlated materials often have remarkable properties and transitions between distinct, competing phases with dramatically different electronic and magnetic orders. These rich phenomena are fascinating from the basic science perspective and offer possibilities for technological applications. This article looks at these materials through the lens of research performed at Rice University. Topics examined include: Quantum phase transitions and quantum criticality in "heavy fermion" materials and the iron pnictide high temperature superconductors; computational ab initio methods to examine strongly correlated materials and their interface with analytical theory techniques; layered dichalcogenides as example correlated materials with rich phases (charge density waves, superconductivity, hard ferromagnetism) that may be tuned by composition, pressure, and magnetic field; and nanostructure methods applied to the correlated oxides VO₂ and Fe₃O₄, where metal-insulator transitions can be manipulated by doping at the nanoscale or driving the system out of equilibrium. We conclude with a discussion of the exciting prospects for this class of materials.

  11. Degenerate Density Perturbation Theory

    CERN Document Server

    Palenik, Mark C

    2016-01-01

    Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of $N_d$ degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X$\\alpha$ exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first through third-order energies as a function of $\\alpha$, with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.

  12. Gluon density in nuclei

    CERN Document Server

    Ayala, A P; Levin, E M

    1996-01-01

    In this talk we present our detail study ( theory and numbers) [1] on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather contraversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula [2] and estimate the value of the shadowing corrections in this case. Than we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus - nucleus cascade.

  13. Quantal density functional theory

    CERN Document Server

    Sahni, Viraht

    2016-01-01

    This book deals with quantal density functional theory (QDFT) which is a time-dependent local effective potential theory of the electronic structure of matter. The treated time-independent QDFT constitutes a special case. In the 2nd edition, the theory is extended to include the presence of external magnetostatic fields. The theory is a description of matter based on the ‘quantal Newtonian’ first and second laws which is in terms of “classical” fields that pervade all space, and their quantal sources. The fields, which are explicitly defined, are separately representative of electron correlations due to the Pauli exclusion principle, Coulomb repulsion, correlation-kinetic, correlation-current-density, and correlation-magnetic effects. The book further describes Schrödinger theory from the new physical perspective of fields and quantal sources. It also describes traditional Hohenberg-Kohn-Sham DFT, and explains via QDFT the physics underlying the various energy functionals and functional derivatives o...

  14. Density-of-states

    CERN Document Server

    Langfeld, Kurt

    2016-01-01

    Although Monte Carlo calculations using Importance Sampling have matured into the most widely employed method for determining first principle results in QCD, they spectacularly fail for theories with a sign problem or for which certain rare configurations play an important role. Non-Markovian Random walks, based upon iterative refinements of the density-of-states, overcome such overlap problems. I will review the Linear Logarithmic Relaxation (LLR) method and, in particular, focus onto ergodicity and exponential error suppression. Applications include the high-state Potts model, SU(2) and SU(3) Yang-Mills theories as well as a quantum field theory with a strong sign problem: QCD at finite densities of heavy quarks.

  15. Degenerate density perturbation theory

    Science.gov (United States)

    Palenik, Mark C.; Dunlap, Brett I.

    2016-09-01

    Fractional occupation numbers can be used in density functional theory to create a symmetric Kohn-Sham potential, resulting in orbitals with degenerate eigenvalues. We develop the corresponding perturbation theory and apply it to a system of Nd degenerate electrons in a harmonic oscillator potential. The order-by-order expansions of both the fractional occupation numbers and unitary transformations within the degenerate subspace are determined by the requirement that a differentiable map exists connecting the initial and perturbed states. Using the X α exchange-correlation (XC) functional, we find an analytic solution for the first-order density and first- through third-order energies as a function of α , with and without a self-interaction correction. The fact that the XC Hessian is not positive definite plays an important role in the behavior of the occupation numbers.

  16. Buoyant densities of phototrophic sulfur bacteria and cyanobacteria

    Science.gov (United States)

    Guerrero, R.

    1985-01-01

    The buoyant densities of bacterial cells are greatly influenced by the accumulation of intracellular reserve material. The buoyant density of phototrophic bacteria that are planktonic is of particular interest, since these organisms must remain in the photic zone of the water column for optimal growth. Separation of cells by their buoyant density may also be of use in separating and identifying organisms from a natural population. The bacteria used were obtained from pure cultures, enrichments, or samples taken directly from the environment.

  17. Low-dislocation-density epitatial layers grown by defect filtering by self-assembled layers of spheres

    Science.gov (United States)

    Wang, George T.; Li, Qiming

    2013-04-23

    A method for growing low-dislocation-density material atop a layer of the material with an initially higher dislocation density using a monolayer of spheroidal particles to bend and redirect or directly block vertically propagating threading dislocations, thereby enabling growth and coalescence to form a very-low-dislocation-density surface of the material, and the structures made by this method.

  18. Airborne Crowd Density Estimation

    Science.gov (United States)

    Meynberg, O.; Kuschk, G.

    2013-10-01

    This paper proposes a new method for estimating human crowd densities from aerial imagery. Applications benefiting from an accurate crowd monitoring system are mainly found in the security sector. Normally crowd density estimation is done through in-situ camera systems mounted on high locations although this is not appropriate in case of very large crowds with thousands of people. Using airborne camera systems in these scenarios is a new research topic. Our method uses a preliminary filtering of the whole image space by suitable and fast interest point detection resulting in a number of image regions, possibly containing human crowds. Validation of these candidates is done by transforming the corresponding image patches into a low-dimensional and discriminative feature space and classifying the results using a support vector machine (SVM). The feature space is spanned by texture features computed by applying a Gabor filter bank with varying scale and orientation to the image patches. For evaluation, we use 5 different image datasets acquired by the 3K+ aerial camera system of the German Aerospace Center during real mass events like concerts or football games. To evaluate the robustness and generality of our method, these datasets are taken from different flight heights between 800 m and 1500 m above ground (keeping a fixed focal length) and varying daylight and shadow conditions. The results of our crowd density estimation are evaluated against a reference data set obtained by manually labeling tens of thousands individual persons in the corresponding datasets and show that our method is able to estimate human crowd densities in challenging realistic scenarios.

  19. 46 CFR 151.03-21 - Filling density.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Filling density. 151.03-21 Section 151.03-21 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Definitions § 151.03-21 Filling density. The ratio, expressed as...

  20. Contingent kernel density estimation.

    Directory of Open Access Journals (Sweden)

    Scott Fortmann-Roe

    Full Text Available Kernel density estimation is a widely used method for estimating a distribution based on a sample of points drawn from that distribution. Generally, in practice some form of error contaminates the sample of observed points. Such error can be the result of imprecise measurements or observation bias. Often this error is negligible and may be disregarded in analysis. In cases where the error is non-negligible, estimation methods should be adjusted to reduce resulting bias. Several modifications of kernel density estimation have been developed to address specific forms of errors. One form of error that has not yet been addressed is the case where observations are nominally placed at the centers of areas from which the points are assumed to have been drawn, where these areas are of varying sizes. In this scenario, the bias arises because the size of the error can vary among points and some subset of points can be known to have smaller error than another subset or the form of the error may change among points. This paper proposes a "contingent kernel density estimation" technique to address this form of error. This new technique adjusts the standard kernel on a point-by-point basis in an adaptive response to changing structure and magnitude of error. In this paper, equations for our contingent kernel technique are derived, the technique is validated using numerical simulations, and an example using the geographic locations of social networking users is worked to demonstrate the utility of the method.

  1. Analytic materials.

    Science.gov (United States)

    Milton, Graeme W

    2016-11-01

    The theory of inhomogeneous analytic materials is developed. These are materials where the coefficients entering the equations involve analytic functions. Three types of analytic materials are identified. The first two types involve an integer p. If p takes its maximum value, then we have a complete analytic material. Otherwise, it is incomplete analytic material of rank p. For two-dimensional materials, further progress can be made in the identification of analytic materials by using the well-known fact that a 90(°) rotation applied to a divergence-free field in a simply connected domain yields a curl-free field, and this can then be expressed as the gradient of a potential. Other exact results for the fields in inhomogeneous media are reviewed. Also reviewed is the subject of metamaterials, as these materials provide a way of realizing desirable coefficients in the equations.

  2. Analytic Materials

    CERN Document Server

    Milton, Graeme W

    2016-01-01

    The theory of inhomogeneous analytic materials is developed. These are materials where the coefficients entering the equations involve analytic functions. Three types of analytic materials are identified. The first two types involve an integer $p$. If $p$ takes its maximum value then we have a complete analytic material. Otherwise it is incomplete analytic material of rank $p$. For two-dimensional materials further progress can be made in the identification of analytic materials by using the well-known fact that a $90^\\circ$ rotation applied to a divergence free field in a simply connected domain yields a curl-free field, and this can then be expressed as the gradient of a potential. Other exact results for the fields in inhomogeneous media are reviewed. Also reviewed is the subject of metamaterials, as these materials provide a way of realizing desirable coefficients in the equations.

  3. Hazardous materials

    Science.gov (United States)

    ... can cause cancer. Know how to use the material and how to store it or throw it away when you are done. Other tips include: Never enter an area where radiation ... materials from one area to another. Check bottles, containers, ...

  4. Density measures and additive property

    OpenAIRE

    Kunisada, Ryoichi

    2015-01-01

    We deal with finitely additive measures defined on all subsets of natural numbers which extend the asymptotic density (density measures). We consider a class of density measures which are constructed from free ultrafilters on natural numbers and study a certain additivity property of such density measures.

  5. Density measures and additive property

    OpenAIRE

    Kunisada, Ryoichi

    2015-01-01

    We deal with finitely additive measures defined on all subsets of natural numbers which extend the asymptotic density (density measures). We consider a class of density measures which are constructed from free ultrafilters on natural numbers and study a certain additivity property of such density measures.

  6. Noncovalent Interactions in Density-Functional Theory

    CERN Document Server

    DiLabio, Gino A

    2014-01-01

    Non-covalent interactions are essential in the description of soft matter, including materials of technological importance and biological molecules. In density-functional theory, common approaches fail to describe dispersion forces, an essential component in noncovalent binding interactions. In the last decade, great progress has been made in the development of accurate and computationally-efficient methods to describe noncovalently bound systems within the framework of density-functional theory. In this review, we give an account of the field from a chemical and didactic perspective, describing different approaches to the calculation of dispersion energies and comparing their accuracy, complexity, popularity, and general availability. This review should be useful to the newcomer who wants to learn more about noncovalent interactions and the different methods available at present to describe them using density-functional theory.

  7. Semiclassics in Density Functional Theory

    Science.gov (United States)

    Lee, Donghyung; Cangi, Attila; Elliott, Peter; Burke, Kieron

    2009-03-01

    Recently, we published an article [1] about the semiclassical origin of density functional theory. We showed that the density and the kinetic energy density of one dimensional finite systems with hard walls can be expressed in terms of the external potential using the semiclassical Green's function method. Here, we show a uniformization scheme for the semiclassical density and the kinetic energy density for turning-point problems.[1] P. Elliott, D. Lee, A. Cangi, and K. Burke, Phys. Rev. Lett. 100, 256406 (2008).

  8. Insight and progress in density functional theory

    Science.gov (United States)

    Yang, Weitao; Mori-Sanchez, Paula; Cohen, Aron J.

    2012-12-01

    Density functional theory of electronic structure is widely and successfully applied in simulations throughout engineering and sciences. However, there are spectacular failures for many predicted properties. The errors include underestimation of the barriers of chemical reactions, the band gaps of materials, the energies of dissociating molecular ions and charge transfer excitation energies. Typical DFT calculations also fail to describe degenerate or near degenerate systems, as arise in the breaking of chemical bonds, and strongly correlated materials. These errors can all be characterized and understood through the perspective of fractional charges and fractional spins introduced recently.

  9. Method of high-density foil fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Blue, Craig A.; Sikka, Vinod K.; Ohriner, Evan K.

    2003-12-16

    A method for preparing flat foils having a high density includes the steps of mixing a powdered material with a binder to form a green sheet. The green sheet is exposed to a high intensity radiative source adapted to emit radiation of wavelengths corresponding to an absorption spectrum of the powdered material. The surface of the green sheet is heated while a lower sub-surface temperature is maintained. An apparatus for preparing a foil from a green sheet using a radiation source is also disclosed.

  10. Standard Penetration Test and Relative Density

    Science.gov (United States)

    1971-02-01

    laboratorio ejecutados con un penetr6metro est’tico pequeno. INTRODUCTION One of the main problems encountered in subsoil e’xploration is in situ...would be more valid. REFERENCES Burmister, D. M. �), "The Grading-Density Relation of Gr•anular Materials ." Proc,.edings of the American Society for...Reclamation (1953), "Second Progress Report of Re- search of the Penetration Resistance Method of Subsurface Explora- tion," Report No. EM-356. Design and Construction Division, Earth Materials Laboratory, Denver,

  11. Reduced density-matrix functionals from many-particle theory

    Science.gov (United States)

    Schade, Robert; Kamil, Ebad; Blöchl, Peter

    2017-07-01

    In materials with strong electron correlation the proper treatment of local atomic physics described by orbital occupations is crucial. Reduced density-matrix functional theory is a natural extension of density functional theory for systems that are dominated by orbital physics. We review the current state of reduced density-matrix functional theory (RDMFT). For atomic structure relaxations or ab-initio molecular dynamics the combination of density functional theory (DFT) and dynamical mean-field theory (DMFT) possesses a number of disadvantages, like the cumbersome evaluation of forces. We therefore describe a method, DFT+RDMFT, that combines many-particle effects based on reduced density-matrix functional theory with a density functional-like framework. A recent development is the construction of density-matrix functionals directly from many-particle theory such as methods from quantum chemistry or many-particle Green's functions. We present the underlying exact theorems and describe current progress towards quantitative functionals.

  12. High density photovoltaic

    Energy Technology Data Exchange (ETDEWEB)

    Haigh, R.E.; Jacobson, G.F.; Wojtczuk, S. [Spire Corp., Bedford, MA (United States)

    1997-10-14

    Photovoltaic technology can directly generate high voltages in a solid state material through the series interconnect of many photovoltaic diodes. We are investigating the feasibility of developing an electrically isolated, high-voltage power supply using miniature photovoltaic devices that convert optical energy to electrical energy.

  13. Density Distribution Sunflower Plots

    Directory of Open Access Journals (Sweden)

    William D. Dupont

    2003-01-01

    Full Text Available Density distribution sunflower plots are used to display high-density bivariate data. They are useful for data where a conventional scatter plot is difficult to read due to overstriking of the plot symbol. The x-y plane is subdivided into a lattice of regular hexagonal bins of width w specified by the user. The user also specifies the values of l, d, and k that affect the plot as follows. Individual observations are plotted when there are less than l observations per bin as in a conventional scatter plot. Each bin with from l to d observations contains a light sunflower. Other bins contain a dark sunflower. In a light sunflower each petal represents one observation. In a dark sunflower, each petal represents k observations. (A dark sunflower with p petals represents between /2-pk k and /2+pk k observations. The user can control the sizes and colors of the sunflowers. By selecting appropriate colors and sizes for the light and dark sunflowers, plots can be obtained that give both the overall sense of the data density distribution as well as the number of data points in any given region. The use of this graphic is illustrated with data from the Framingham Heart Study. A documented Stata program, called sunflower, is available to draw these graphs. It can be downloaded from the Statistical Software Components archive at http://ideas.repec.org/c/boc/bocode/s430201.html . (Journal of Statistical Software 2003; 8 (3: 1-5. Posted at http://www.jstatsoft.org/index.php?vol=8 .

  14. Composite Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. "Composite Materials" provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the significance of phase geometry....... The book enables the reader to a better understanding of the behavior of natural composites, improvement of such materials, and design of new materials with prescribed properties. A number of examples are presented: Special composite properties considered are stiffness, shrinkage, hygro-thermal behavior...... materials. Numerical procedures are outlined which facilitate the practical analysis of any feature considered in this book. Examples are presented which illustrate the analysis of well-known materials such as concrete, hardening cement paste, ceramics, tile, wood, impregnated and reinforced materials...

  15. Sensor-Free Surface Density Detector

    Science.gov (United States)

    Wu, Huixuan

    2016-11-01

    We have developed an optical-based method to measure the absolute air density on a wall surface in compressible turbulent boundary layers. The temporal resolution can be higher than 1MHz, and the spatial resolution can research 10 micron. For isothermal flows, our system can also be used to obtain the wall pressure distributions or volume-ratio of two-species gas. It is a powerful tool for observing turbulent fluctuations and flow separations in sub-, trans-, and supersonic airflows. The working principle of our method is to detect the air density by measuring the refractive index, which linearly depends on density and determines the transmission coefficient at the interface. For single- or multiple-point measurements, we do not need to install sensors on the wall surface, which is a big advantage compared to conventional methods. In 2D cases, a layer of anti-reflection coating is needed. The optical measurement range is not limited by the surface material or sensor. These advantages make our method a good complement or better alternative to the other approaches, such as focused laser differential interferometry technique, which provides density gradient, and pressure (temperature) sensitive paints, which depends significantly on the material properties.

  16. Aerospace materials and material technologies

    CERN Document Server

    Wanhill, R

    2017-01-01

    This book is a comprehensive compilation of chapters on materials (both established and evolving) and material technologies that are important for aerospace systems. It considers aerospace materials in three Parts. Part I covers Metallic Materials (Mg, Al, Al-Li, Ti, aero steels, Ni, intermetallics, bronzes and Nb alloys); Part II deals with Composites (GLARE, PMCs, CMCs and Carbon based CMCs); and Part III considers Special Materials. This compilation has ensured that no important aerospace material system is ignored. Emphasis is laid in each chapter on the underlying scientific principles as well as basic and fundamental mechanisms leading to processing, characterization, property evaluation and applications. A considerable amount of materials data is compiled and presented in appendices at the end of the book. This book will be useful to students, researchers and professionals working in the domain of aerospace materials.

  17. Discrete density of states

    Science.gov (United States)

    Aydin, Alhun; Sisman, Altug

    2016-03-01

    By considering the quantum-mechanically minimum allowable energy interval, we exactly count number of states (NOS) and introduce discrete density of states (DOS) concept for a particle in a box for various dimensions. Expressions for bounded and unbounded continua are analytically recovered from discrete ones. Even though substantial fluctuations prevail in discrete DOS, they're almost completely flattened out after summation or integration operation. It's seen that relative errors of analytical expressions of bounded/unbounded continua rapidly decrease for high NOS values (weak confinement or high energy conditions), while the proposed analytical expressions based on Weyl's conjecture always preserve their lower error characteristic.

  18. Finite Density Fat QCD

    CERN Document Server

    Aloisio, R; Di Carlo, G; Galante, A; Grillo, A F

    2000-01-01

    Lattice formulation of Finite Baryon Density QCD is problematic from computer simulation point of view; it is well known that for light quark masses the reconstructed partition function fails to be positive in a wide region of parameter space. For large bare quark masses, instead, it is possible to obtain more sensible results; problems are still present but restricted to a small region. We present evidence for a saturation transition independent from the gauge coupling $\\beta$ and for a transition line that, starting from the temperature critical point at $\\mu=0$, moves towards smaller $\\beta$ with increasing $\\mu$ as expected from simplified phenomenological arguments.

  19. Oblique dust density waves

    Science.gov (United States)

    Piel, Alexander; Arp, Oliver; Menzel, Kristoffer; Klindworth, Markus

    2007-11-01

    We report on experimental observations of dust density waves in a complex (dusty) plasma under microgravity. The plasma is produced in a radio-frequency parallel-plate discharge (argon, p=15Pa, U=65Vpp). Different sizes of dust particles were used (3.4 μm and 6.4μm diameter). The low-frequency (f 11Hz) dust density waves are naturally unstable modes, which are driven by the ion flow in the plasma. Surprisingly, the wave propagation direction is aligned with the ion flow direction in the bulk plasma but becomes oblique at the boundary of the dust cloud with an inclination of 60^o with respect to the plasma boundary. The experimental results are compared with a kinetic model in the electrostatic approximation [1] and a fluid model [2]. Moreover, the role of dust surface waves is discussed. [1] M. Rosenberg, J. Vac. Sci. Technol. A 14, 631 (1996) [2] A. Piel et al, Phys. Rev. Lett. 97, 205009 (2006)

  20. Gluon density in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, A.L. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica][Pelotas Univ., RS (Brazil). Inst. de Fisica e Matematica; Ducati, M.B.G. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica; Levin, E.M. [Fermi National Accelerator Lab., Batavia, IL (United States)][Nuclear Physics Inst., St. Petersburg (Russian Federation)

    1996-10-01

    In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab.

  1. Impact of particle density and initial volume on mathematical compression models

    DEFF Research Database (Denmark)

    Sonnergaard, Jørn

    2000-01-01

    on the derived apparent yield pressures. Substances with ionic bonds or macromolecular materials with amorphous structures do not show this dependency on the particle density. The influence of density is demonstrated by performing non-linear regression on the Heckel equation where the optimal particle density...... equations. The problems are illustrated by investigations on compaction profiles of 17 materials with different molecular structures and particle densities. It is shown that the particle density of materials with covalent bonds in the Heckel model acts as a key parameter with a dominating influence...

  2. Gedanken Densities and Exact Constraints in Density Functional Theory

    CERN Document Server

    Perdew, John P; Sun, Jianwei; Burke, Kieron

    2014-01-01

    Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is no...

  3. Material Systems

    DEFF Research Database (Denmark)

    Jensen, Mads Brath; Mortensen, Henrik Rubæk; Mullins, Michael;

    2009-01-01

    This paper describes and reflects upon the results of an investigative project which explores the setting up of a material system - a parametric and generative assembly consisting of and taking into consideration material properties, manufacturing constraints and geometric behavior. The project...... approaches the subject through the construction of a logic-driven system aiming to explore the possibilities of a material system that fulfills spatial, structural and performative requirements concurrently and how these are negotiated in situations where they might be conflicting....

  4. Material Systems

    DEFF Research Database (Denmark)

    Jensen, Mads Brath; Mortensen, Henrik Rubæk; Mullins, Michael

    2009-01-01

    This paper describes and reflects upon the results of an investigative project which explores the setting up of a material system - a parametric and generative assembly consisting of and taking into consideration material properties, manufacturing constraints and geometric behavior. The project...... approaches the subject through the construction of a logic-driven system aiming to explore the possibilities of a material system that fulfills spatial, structural and performative requirements concurrently and how these are negotiated in situations where they might be conflicting....

  5. Density functional theory: Foundations reviewed

    Energy Technology Data Exchange (ETDEWEB)

    Kryachko, Eugene S., E-mail: eugene.kryachko@ulg.ac.be [Bogolyubov Institute for Theoretical Physics, Kiev, 03680 (Ukraine); Ludeña, Eduardo V., E-mail: popluabe@yahoo.es [Centro de Química, Instituto Venezolano de Investigaciones Científicas, IVIC, Apartado 21827, Caracas 1020-A (Venezuela, Bolivarian Republic of); Prometheus Program, Senescyt (Ecuador); Grupo Ecuatoriano para el Estudio Experimental y Teórico de Nanosistemas, GETNano, USFQ, N104-E, Quito (Ecuador); Escuela Politécnica Superior del Litoral, ESPOL, Guayaquil (Ecuador)

    2014-11-10

    Guided by the above motto (quotation), we review a broad range of issues lying at the foundations of Density Functional Theory, DFT, a theory which is currently omnipresent in our everyday computational study of atoms and molecules, solids and nano-materials, and which lies at the heart of modern many-body computational technologies. The key goal is to demonstrate that there are definitely the ways to improve DFT. We start by considering DFT in the larger context provided by reduced density matrix theory (RDMT) and natural orbital functional theory (NOFT), and examine the implications that N-representability conditions on the second-order reduced density matrix (2-RDM) have not only on RDMT and NOFT but, also, by extension, on the functionals of DFT. This examination is timely in view of the fact that necessary and sufficient N-representability conditions on the 2-RDM have recently been attained. In the second place, we review some problems appearing in the original formulation of the first Hohenberg–Kohn theorem which is still a subject of some controversy. In this vein we recall Lieb’s comment on this proof and the extension to this proof given by Pino et al. (2009), and in this context examine the conditions that must be met in order that the one-to-one correspondence between ground-state densities and external potentials remains valid for finite subspaces (namely, the subspaces where all Kohn–Sham solutions are obtained in practical applications). We also consider the issue of whether the Kohn–Sham equations can be derived from basic principles or whether they are postulated. We examine this problem in relation to ab initio DFT. The possibility of postulating arbitrary Kohn–Sham-type equations, where the effective potential is by definition some arbitrary mixture of local and non-local terms, is discussed. We also deal with the issue of whether there exists a universal functional, or whether one should advocate instead the construction of problem

  6. Density Sensitive Hashing

    CERN Document Server

    Lin, Yue; Li, Cheng

    2012-01-01

    Nearest neighbors search is a fundamental problem in various research fields like machine learning, data mining and pattern recognition. Recently, hashing-based approaches, e.g., Locality Sensitive Hashing (LSH), are proved to be effective for scalable high dimensional nearest neighbors search. Many hashing algorithms found their theoretic root in random projection. Since these algorithms generate the hash tables (projections) randomly, a large number of hash tables (i.e., long codewords) are required in order to achieve both high precision and recall. To address this limitation, we propose a novel hashing algorithm called {\\em Density Sensitive Hashing} (DSH) in this paper. DSH can be regarded as an extension of LSH. By exploring the geometric structure of the data, DSH avoids the purely random projections selection and uses those projective functions which best agree with the distribution of the data. Extensive experimental results on real-world data sets have shown that the proposed method achieves better ...

  7. High Density QCD

    CERN Document Server

    Ducati, M B G

    2001-01-01

    The dynamics of high partonic density QCD is presented considering, in the double logarithm approximation, the parton recombination mechanism built in the AGL formalism, developed including unitarity corrections for the nucleon as well for nucleus. It is shown that these corrections are under theoretical control. The resulting non linear evolution equation is solved in the asymptotic regime, and a comprehensive phenomenology concerning Deep Inelastic Scattering like $F_2$, $F_L$, $F_2^c$. $\\partial F_2/ \\partial \\ln Q^2$, $\\partial F^A_2/ \\partial \\ln Q^2$, etc, is presented. The connection of our formalism with the DGLAP and BFKL dynamics, and with other perturbative (K) and non-perturbative (MV-JKLW) approaches is analised in detail. The phenomena of saturation due to shadowing corrections and the relevance of this effect in ion physics and heavy quark production is emphasized. The implications to e-RHIC, HERA-A, and LHC physics and some open questions are mentioned.

  8. Density constrained TDHF

    CERN Document Server

    Oberacker, V E

    2015-01-01

    In this manuscript we provide an outline of the numerical methods used in implementing the density constrained time-dependent Hartree-Fock (DC-TDHF) method and provide a few examples of its application to nuclear fusion. In this approach, dynamic microscopic calculations are carried out on a three-dimensional lattice and there are no adjustable parameters, the only input is the Skyrme effective NN interaction. After a review of the DC-TDHF theory and the numerical methods, we present results for heavy-ion potentials $V(R)$, coordinate-dependent mass parameters $M(R)$, and precompound excitation energies $E^{*}(R)$ for a variety of heavy-ion reactions. Using fusion barrier penetrabilities, we calculate total fusion cross sections $\\sigma(E_\\mathrm{c.m.})$ for reactions between both stable and neutron-rich nuclei. We also determine capture cross sections for hot fusion reactions leading to the formation of superheavy elements.

  9. Bone Densitometry (Bone Density Scan)

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Bone Densitometry (DEXA) Bone densitometry, also called dual-energy ... limitations of DEXA Bone Densitometry? What is a Bone Density Scan (DEXA)? Bone density scanning, also called ...

  10. Earth's density flattening and hypothesis of latitudinal normal density

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the definition of latitudinal density and density flattening of the level ellipsoid is given, and integral formulas of latitudinal density for pole gravity and equator gravity are derived. According to the pole gravity condition and equator gravity condition for the level ellipsoid, latitudinal density distribution function of the level ellipsoid is obtained. It is proved mathematically that latitudinal density of the earth's equator is larger than that of the pole, the earth's density flat-tening calculated preliminarily is 1/322, and hypothesis of the earth's latitudinal normal density is further proposed, so that theoretical preparation for studying the forming cause of the earth gravity in problems such as continent drift, mantle convection, and submarine extension is made well.

  11. Materials characterization

    Energy Technology Data Exchange (ETDEWEB)

    Cheung, N.W.; Nicolet, M.A.

    1986-01-01

    This book presents the papers given at a symposium on the methods used in the chemical analysis of materials. Topics considered at the symposium included emerging techniques for materials microanalysis, scanning electron microscopy, Raman spectroscopy, Auger electron spectroscopy, crystal lattices, computerized tomography using synchrotron radiation, epitaxy, photoconductivity, elastic properties, neutron-induced particle track mapping of elemental distributions, and point defects in crystals.

  12. Bone Densitometry (Bone Density Scan)

    Science.gov (United States)

    ... of DXA Bone Densitometry? What is a Bone Density Scan (DXA)? Bone density scanning, also called dual-energy x-ray absorptiometry ( ... is today's established standard for measuring bone mineral density (BMD). An x-ray (radiograph) is a noninvasive ...

  13. Supercapacitors specialities - Materials review

    Science.gov (United States)

    Obreja, Vasile V. N.

    2014-06-01

    The electrode material is a key component for supercapacitor cell performance. As it is known, performance comparison of commercial available batteries and supercapacitors reveals significantly lower energy storage capability for supercapacitor devices. The energy density of commercial supercapacitor cells is limited to 10 Wh/kg whereas that of common lead acid batteries reaches 35-40 Wh/kg. For lithium ion batteries a value higher than 100 Wh/kg is easily available. Nevertheless, supercapacitors also known as ultracapacitors or electrochemical capacitors have other advantages in comparison with batteries. As a consequence, many efforts have been made in the last years to increase the storage energy density of electrochemical capacitors. A lot of results from published work (research and review papers, patents and reports) are available at this time. The purpose of this review is a presentation of the progress to date for the use of new materials and approaches for supercapacitor electrodes, with focus on the energy storage capability for practical applications. Many reported results refer to nanostructured carbon based materials and the related composites, used for the manufacture of experimental electrodes. A specific capacitance and a specific energy are seldom revealed as the main result of the performed investigation. Thus for nanoprous (activated) carbon based electrodes a specific capacitance up to 200-220 F/g is mentioned for organic electrolyte, whereas for aqueous electrolyte, the value is limited to 400-500 F/g. Significant contribution to specific capacitance is possible from fast faradaic reactions at the electrode-electrolyte interface in addition to the electric double layer effect. The corresponding energy density is limited to 30-50 Wh/kg for organic electrolyte and to 12-17 Wh/kg for aqueous electrolyte. However such performance indicators are given only for the carbon material used in electrodes. For a supercapacitor cell, where two electrodes

  14. Bioresponsive materials

    Science.gov (United States)

    Lu, Yue; Aimetti, Alex A.; Langer, Robert; Gu, Zhen

    2016-10-01

    'Smart' bioresponsive materials that are sensitive to biological signals or to pathological abnormalities, and interact with or are actuated by them, are appealing therapeutic platforms for the development of next-generation precision medications. Armed with a better understanding of various biologically responsive mechanisms, researchers have made innovations in the areas of materials chemistry, biomolecular engineering, pharmaceutical science, and micro- and nanofabrication to develop bioresponsive materials for a range of applications, including controlled drug delivery, diagnostics, tissue engineering and biomedical devices. This Review highlights recent advances in the design of smart materials capable of responding to the physiological environment, to biomarkers and to biological particulates. Key design principles, challenges and future directions, including clinical translation, of bioresponsive materials are also discussed.

  15. Composite material

    Science.gov (United States)

    Hutchens, Stacy A.; Woodward, Jonathan; Evans, Barbara R.; O'Neill, Hugh M.

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  16. Periodontal materials.

    Science.gov (United States)

    Darby, I

    2011-06-01

    Periodontics is more associated with debridement of periodontal pockets and not generally thought of as using dental materials in the treatment of patients. However, the last 30 years have seen the development of materials used in regeneration of the periodontal tissues following periodontal disease, guided tissue regeneration, and the use of these materials in bone regeneration more recently, guided bone regeneration. The materials used include bone grafts and membranes, but also growth factors and cells-based therapies. This review provides an overview of the materials currently used and looks at contemporary research with a view to what may be used in the future. It also looks at the clinical effectiveness of these regenerative therapies with an emphasis on what is available in Australia.

  17. Bioresponsive materials

    Science.gov (United States)

    Lu, Yue; Aimetti, Alex A.; Langer, Robert; Gu, Zhen

    2017-01-01

    'Smart' bioresponsive materials that are sensitive to biological signals or to pathological abnormalities, and interact with or are actuated by them, are appealing therapeutic platforms for the development of next-generation precision medications. Armed with a better understanding of various biologically responsive mechanisms, researchers have made innovations in the areas of materials chemistry, biomolecular engineering, pharmaceutical science, and micro- and nanofabrication to develop bioresponsive materials for a range of applications, including controlled drug delivery, diagnostics, tissue engineering and biomedical devices. This Review highlights recent advances in the design of smart materials capable of responding to the physiological environment, to biomarkers and to biological particulates. Key design principles, challenges and future directions, including clinical translation, of bioresponsive materials are also discussed.

  18. High Volumetric Energy Density Hybrid Supercapacitors Based on Reduced Graphene Oxide Scrolls.

    Science.gov (United States)

    Rani, Janardhanan R; Thangavel, Ranjith; Oh, Se-I; Woo, Jeong Min; Chandra Das, Nayan; Kim, So-Yeon; Lee, Yun-Sung; Jang, Jae-Hyung

    2017-07-12

    The low volumetric energy density of reduced graphene oxide (rGO)-based electrodes limits its application in commercial electrochemical energy storage devices that require high-performance energy storage capacities in small volumes. The volumetric energy density of rGO-based electrode materials is very low due to their low packing density. A supercapacitor with enhanced packing density and high volumetric energy density is fabricated using doped rGO scrolls (GFNSs) as the electrode material. The restacking of rGO sheets is successfully controlled through synthesizing the doped scroll structures while increasing the packing density. The fabricated cell exhibits an ultrahigh volumetric energy density of 49.66 Wh/L with excellent cycling stability (>10 000 cycles). This unique design strategy for the electrode material has significant potential for the future supercapacitors with high volumetric energy densities.

  19. Carbon nanotube growth density control

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  20. Density Estimations in Laboratory Debris Flow Experiments

    Science.gov (United States)

    Queiroz de Oliveira, Gustavo; Kulisch, Helmut; Malcherek, Andreas; Fischer, Jan-Thomas; Pudasaini, Shiva P.

    2016-04-01

    Bulk density and its variation is an important physical quantity to estimate the solid-liquid fractions in two-phase debris flows. Here we present mass and flow depth measurements for experiments performed in a large-scale laboratory set up. Once the mixture is released and it moves down the inclined channel, measurements allow us to determine the bulk density evolution throughout the debris flow. Flow depths are determined by ultrasonic pulse reflection, and the mass is measured with a total normal force sensor. The data were obtained at 50 Hz. The initial two phase material was composed of 350 kg debris with water content of 40%. A very fine pebble with mean particle diameter of 3 mm, particle density of 2760 kg/m³ and bulk density of 1400 kg/m³ in dry condition was chosen as the solid material. Measurements reveal that the debris bulk density remains high from the head to the middle of the debris body whereas it drops substantially at the tail. This indicates lower water content at the tail, compared to the head and the middle portion of the debris body. This means that the solid and fluid fractions are varying strongly in a non-linear manner along the flow path, and from the head to the tail of the debris mass. Importantly, this spatial-temporal density variation plays a crucial role in determining the impact forces associated with the dynamics of the flow. Our setup allows for investigating different two phase material compositions, including large fluid fractions, with high resolutions. The considered experimental set up may enable us to transfer the observed phenomena to natural large-scale events. Furthermore, the measurement data allows evaluating results of numerical two-phase mass flow simulations. These experiments are parts of the project avaflow.org that intends to develop a GIS-based open source computational tool to describe wide spectrum of rapid geophysical mass flows, including avalanches and real two-phase debris flows down complex natural

  1. Density sensitive hashing.

    Science.gov (United States)

    Jin, Zhongming; Li, Cheng; Lin, Yue; Cai, Deng

    2014-08-01

    Nearest neighbor search is a fundamental problem in various research fields like machine learning, data mining and pattern recognition. Recently, hashing-based approaches, for example, locality sensitive hashing (LSH), are proved to be effective for scalable high dimensional nearest neighbor search. Many hashing algorithms found their theoretic root in random projection. Since these algorithms generate the hash tables (projections) randomly, a large number of hash tables (i.e., long codewords) are required in order to achieve both high precision and recall. To address this limitation, we propose a novel hashing algorithm called density sensitive hashing (DSH) in this paper. DSH can be regarded as an extension of LSH. By exploring the geometric structure of the data, DSH avoids the purely random projections selection and uses those projective functions which best agree with the distribution of the data. Extensive experimental results on real-world data sets have shown that the proposed method achieves better performance compared to the state-of-the-art hashing approaches.

  2. Generating random density matrices

    CERN Document Server

    Zyczkowski, Karol; Nechita, Ion; Collins, Benoit

    2010-01-01

    We study various methods to generate ensembles of quantum density matrices of a fixed size N and analyze the corresponding probability distributions P(x), where x denotes the rescaled eigenvalue, x=N\\lambda. Taking a random pure state of a two-partite system and performing the partial trace over one subsystem one obtains a mixed state represented by a Wishart--like matrix W=GG^{\\dagger}, distributed according to the induced measure and characterized asymptotically, as N -> \\infty, by the Marchenko-Pastur distribution. Superposition of k random maximally entangled states leads to another family of explicitly derived distributions, describing singular values of the sum of k independent random unitaries. Taking a larger system composed of 2s particles, constructing $s$ random bi-partite states, performing the measurement into a product of s-1 maximally entangled states and performing the partial trace over the remaining subsystem we arrive at a random state characterized by the Fuss-Catalan distribution of order...

  3. Flash sintering of ceramic materials

    OpenAIRE

    Dancer, C. E. J.

    2016-01-01

    During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sint...

  4. Accurate ab initio spin densities

    CERN Document Server

    Boguslawski, Katharina; Legeza, Örs; Reiher, Markus

    2012-01-01

    We present an approach for the calculation of spin density distributions for molecules that require very large active spaces for a qualitatively correct description of their electronic structure. Our approach is based on the density-matrix renormalization group (DMRG) algorithm to calculate the spin density matrix elements as basic quantity for the spatially resolved spin density distribution. The spin density matrix elements are directly determined from the second-quantized elementary operators optimized by the DMRG algorithm. As an analytic convergence criterion for the spin density distribution, we employ our recently developed sampling-reconstruction scheme [J. Chem. Phys. 2011, 134, 224101] to build an accurate complete-active-space configuration-interaction (CASCI) wave function from the optimized matrix product states. The spin density matrix elements can then also be determined as an expectation value employing the reconstructed wave function expansion. Furthermore, the explicit reconstruction of a CA...

  5. Computing dispersion interactions in density functional theory

    Science.gov (United States)

    Cooper, V. R.; Kong, L.; Langreth, D. C.

    2010-02-01

    In this article techniques for including dispersion interactions within density functional theory are examined. In particular comparisons are made between four popular methods: dispersion corrected DFT, pseudopotential correction schemes, symmetry adapted perturbation theory, and a non-local density functional - the so called Rutgers-Chalmers van der Waals density functional (vdW-DF). The S22 benchmark data set is used to evaluate the relative accuracy of these methods and factors such as scalability and transferability are also discussed. We demonstrate that vdW-DF presents an excellent compromise between computational speed and accuracy and lends most easily to full scale application in solid materials. This claim is supported through a brief discussion of a recent large scale application to H2 in a prototype metal organic framework material (MOF), Zn2BDC2TED. The vdW-DF shows overwhelming promise for first-principles studies of physisorbed molecules in porous extended systems; thereby having broad applicability for studies as diverse as molecular adsorption and storage, battery technology, catalysis and gas separations.

  6. Thermoelectric studies of charge density wave dynamics.

    Science.gov (United States)

    McDonald, Ross; Harrison, Neil; Singleton, John

    2008-03-01

    The conventional pyroelectric effect is intimately connected to the symmetry, or rather lack of center of symmetry, of the material. Although the experiments we discuss involve studies of low symmetry materials, the pyroelectric currents observed are of an entirely new origin. Systems with broken-translational-symmetry phases that incorporate orbital quantization can exhibit significant departures from thermodynamic equilibrium due to a change in magnetic induction. For charge density wave systems, this metastable state consists of a balance between the density-wave pinning force and the Lorentz force on the extended currents due to the drift of cyclotron orbits. In this way the density wave pinning potential plays a similar role to the edge potential in a two-dimensional electron gas, leading to a large Hall angle and quantization of the Hall resistance. A thermal perturbation that reduces the pinning potential returns the system towards thermal equilibrium, via a phason avalanche orthogonal to the sample surface. The observation of this new form of pyroelectric effect in the high magnetic field phase (B > 30 T) of the organic charge transfer salt α-(BEDT-TTF)2KHg(SCN)4, thus provides a measure of the phason thermopower.

  7. Radioactive Material

    CERN Multimedia

    2004-01-01

    The Radiation Protection Group of the Safety Commission is responsible for shipping of radioactive material from CERN to any external institute or organisation. The RP group is equally responsible for the reception of radioactive material shipped to any of the CERN sites. Anyone who needs to ship from or import into CERN radioactive material must contact the Radioactive Shipping Service of the RP group in advance. Instructions are available at: http://cern.ch/rp-shipping or in the Radiation Protection Procedure PRP13: https://edms.cern.ch/document/346823 Radiation Protection Group

  8. Radioactive Material

    CERN Multimedia

    2004-01-01

    The Radiation Protection Group of the Safety Commission is responsible for shipping of radioactive material from CERN to any external institute or organisation. The RP group is equally responsible for the reception of radioactive material shipped to any of the CERN sites. Anyone who needs to ship from or import into CERN radioactive material must contact the Radioactive Shipping Service of the RP group in advance. Instructions are available at: http://cern.ch/rp-shipping or in the Radiation Protection Procedure PRP13: https://edms.cern.ch/document/346823 Radiation Protection Group

  9. Broadband giant-refractive-index material based on mesoscopic space-filling curves

    National Research Council Canada - National Science Library

    Chang, Taeyong; Kim, Jong Uk; Kang, Seung Kyu; Kim, Hyowook; Kim, Do Kyung; Lee, Yong-Hee; Shin, Jonghwa

    2016-01-01

    The refractive index is the fundamental property of all optical materials and dictates Snell's law, propagation speed, wavelength, diffraction, energy density, absorption and emission of light in materials...

  10. Virtual materiality

    DEFF Research Database (Denmark)

    Søndergaard, Dorte Marie

    an interesting platform for further development including virtual materiality and agency. If we choose to proceed along this line – some of our steps would include attention to the following points: 1. Working with virtual realities first of all undermines a pure realist conceptualization of materiality. We need......There are two questions that feed the curiosity of this paper: a theoretical question connected to the conceptualization of materiality across the real/virtual divide and an empirical question connected to the understanding of virtual experiences in children’s lives when studied in relation...... as their recounts of them and 3. the consumption of other media products like movies, reality shows, YouTube videos etc. How do we theorize ‘matter’ in such dimensions? Is it possible to theorize virtual matter as ‘materiality’ in line with any real life materiality? What conceptualization will help us understand...

  11. Size effect in thermoelectric materials

    Science.gov (United States)

    Mao, Jun; Liu, Zihang; Ren, Zhifeng

    2016-12-01

    Thermoelectric applications have attracted increasing interest recently due to its capability of converting waste heat into electricity without hazardous emissions. Materials with enhanced thermoelectric performance have been reported in recent two decades. The revival of research for thermoelectric materials began in early 1990s when the size effect is considered. Low-dimensional materials with exceptionally high thermoelectric figure of merit (ZT) have been presented, which broke the limit of ZT around unity. The idea of size effect in thermoelectric materials even inspired the later nanostructuring and band engineering strategies, which effectively enhanced the thermoelectric performance of bulk materials. In this overview, the size effect in low-dimensional thermoelectric materials is reviewed. We first discuss the quantum confinement effect on carriers, including the enhancement of electronic density of states, semimetal to semiconductor transition and carrier pocket engineering. Then, the effect of assumptions on theoretical calculations is presented. Finally, the effect of phonon confinement and interface scattering on lattice thermal conductivity is discussed.

  12. Encountering Materiality

    DEFF Research Database (Denmark)

    Svabo, Connie

    2016-01-01

    DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016.......DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016....

  13. Background Material

    DEFF Research Database (Denmark)

    Zandersen, Marianne; Hyytiäinen, Kari; Saraiva, Sofia

    2016-01-01

    This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders.......This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders....

  14. Encountering Materiality

    DEFF Research Database (Denmark)

    Svabo, Connie

    2016-01-01

    DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016.......DHT researcher Connie Svabo and artist Charlotte Grum did a joint performance presentation titled Becoming Sheep, Becoming Animal at the international conference Encountering Materiality – Transdisciplinary Conversations, held in Geneve, Schwitzerland, June 23-25 2016....

  15. Propulsion materials

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Edward J. [U.S. Dept. of Energy, Washington, D.C. (United States); Sullivan, Rogelio A. [U.S. Dept. of Energy, Washington, D.C. (United States); Gibbs, Jerry L. [U.S. Dept. of Energy, Washington, D.C. (United States)

    2008-01-01

    The Department of Energy’s (DOE’s) Office of Vehicle Technologies (OVT) is pleased to introduce the FY 2007 Annual Progress Report for the Propulsion Materials Research and Development Program. Together with DOE national laboratories and in partnership with private industry and universities across the United States, the program continues to engage in research and development (R&D) that provides enabling materials technology for fuel-efficient and environmentally friendly commercial and passenger vehicles.

  16. Nanostructured Materials

    Science.gov (United States)

    2012-08-30

    with macroscopic reinforcements such as fiber, clay, glass mineral and other fillers. The nano-alloyed polymers are particularly useful for producing...applications, including space-sur- vivable materials and seals, gaskets, cosmetics , and personal care. 25 Claims, 10 Drawing Sheets B-3 U.S. Patent Mar...the incorporation of fluorinated nanostructured chemicals onto the surface of a secondary material (such as Ti02 , CaC03 , glass or mineral

  17. Advanced materials for energy storage.

    Science.gov (United States)

    Liu, Chang; Li, Feng; Ma, Lai-Peng; Cheng, Hui-Ming

    2010-02-23

    Popularization of portable electronics and electric vehicles worldwide stimulates the development of energy storage devices, such as batteries and supercapacitors, toward higher power density and energy density, which significantly depends upon the advancement of new materials used in these devices. Moreover, energy storage materials play a key role in efficient, clean, and versatile use of energy, and are crucial for the exploitation of renewable energy. Therefore, energy storage materials cover a wide range of materials and have been receiving intensive attention from research and development to industrialization. In this Review, firstly a general introduction is given to several typical energy storage systems, including thermal, mechanical, electromagnetic, hydrogen, and electrochemical energy storage. Then the current status of high-performance hydrogen storage materials for on-board applications and electrochemical energy storage materials for lithium-ion batteries and supercapacitors is introduced in detail. The strategies for developing these advanced energy storage materials, including nanostructuring, nano-/microcombination, hybridization, pore-structure control, configuration design, surface modification, and composition optimization, are discussed. Finally, the future trends and prospects in the development of advanced energy storage materials are highlighted.

  18. Recycling of irradiated high-density polyethylene

    Science.gov (United States)

    Navratil, J.; Manas, M.; Mizera, A.; Bednarik, M.; Stanek, M.; Danek, M.

    2015-01-01

    Radiation crosslinking of high-density polyethylene (HDPE) is a well-recognized modification of improving basic material characteristics. This research paper deals with the utilization of electron beam irradiated HDPE (HDPEx) after the end of its lifetime. Powder of recycled HDPEx (irradiation dose 165 kGy) was used as a filler into powder of virgin low-density polyethylene (LDPE) in concentrations ranging from 10% to 60%. The effect of the filler on processability and mechanical behavior of the resulting mixtures was investigated. The results indicate that the processability, as well as mechanical behavior, highly depends on the amount of the filler. Melt flow index dropped from 13.7 to 0.8 g/10 min comparing the lowest and the highest concentration; however, the higher shear rate the lower difference between each concentration. Toughness and hardness, on the other hand, grew with increasing addition of the recycled HDPEx. Elastic modulus increased from 254 to 450 MPa and material hardness increased from 53 to 59 ShD. These results indicate resolving the problem of further recycling of irradiated polymer materials while taking advantage of the improved mechanical properties.

  19. Synthesis, characterization, thermal behaviour and single crystal X-ray analysis of two new insensitive high energy density materials [8-hydroxyquinolinium 5-(2,4,6-trinitrophenyl)barbiturate (I) and 8-hydroxyquinolinium 5-(5-chloro-2,4-dinitrophenyl)-1,3-dimethyl barbiturate (II)

    Science.gov (United States)

    Manickkam, V.; Devi, P. Poornima; Kalaivani, D.

    2014-12-01

    Barbiturates I and II have been synthesized as maroon red and red orange coloured solids by mixing the ethanolic solutions of 2-chloro-1,3,5-trinitrobenzene ( TNCB), pyrimidine-2,4,6(1 H,3 H,5 H)-trione [barbituric acid ( BA)] and 8-hydroxyquinoline and 1,3-dichloro-4,6-dinitrobenzene ( DCDNB), 1,3-dimethylpyrimidine-2,4,6(1 H,3 H,5 H)-trione(1,3-dimethylbarbituric acid) and 8-hydroxyquinoline respectively. The structures of these two barbiturates have been predicted from the spectral studies (UV-VIS, IR, 1H NMR, 13C NMR, mass) and elemental analysis. Qualitative tests have been carried out to infer the presence of nitrogen and nitro groups and also chlorine atom in barbiturate II. Slow evaporation of ethanol-dimethylsulphoxide/ethanol solutions of barbiturate I/barbiturate II at 293 K yielded good for X-Ray diffraction crystals. Single crystal X-ray diffraction studies of the crystals further confirm the putative structures of the barbiturates. The asymmetric unit of the barbiturate I comprises of 8-hydroxyquinolinium cation, 5-(2,4,6-trinitrophenyl) barbiturate anion and a molecule of dimethylsulphoxide (DMSO), which is used as a recrystallizing solvent. It crystallizes in the triclinic system with space group (centrosymmetric). Barbiturate II crystallizes in the orthorhombic system with space group P212121 (non-centrosymmetric). Barbiturates I and II are stable towards an impact sensitivity test, when a weight of 2 kg mass hammer is dropped from a height of 160 cm of the instrument. TGA/ DTA analyses at four different heating rates (5, 10, 20, and 40 K/min) imply that they undergo exothermic decomposition (˜85%) in three different stages between 273 and 873 K. Activation energies for these decomposition processes have been calculated by employing Kissinger and Ozawa plots. Impact sensitivity test and activation energies have revealed that the titled barbiturates are insensitive high energy density materials ( IHEDMS).

  20. Pressure Correction in Density Functional Theory Calculations

    CERN Document Server

    Lee, S H

    2008-01-01

    First-principles calculations based on density functional theory have been widely used in studies of the structural, thermoelastic, rheological, and electronic properties of earth-forming materials. The exchange-correlation term, however, is implemented based on various approximations, and this is believed to be the main reason for discrepancies between experiments and theoretical predictions. In this work, by using periclase MgO as a prototype system we examine the discrepancies in pressure and Kohn-Sham energy that are due to the choice of the exchange-correlation functional. For instance, we choose local density approximation and generalized gradient approximation. We perform extensive first-principles calculations at various temperatures and volumes and find that the exchange-correlation-based discrepancies in Kohn-Sham energy and pressure should be independent of temperature. This implies that the physical quantities, such as the equation of states, heat capacity, and the Gr\\"{u}neisen parameter, estimat...

  1. Density functional theory a practical introduction

    CERN Document Server

    Sholl, David

    2009-01-01

    Demonstrates how anyone in math, science, and engineering can master DFT calculations Density functional theory (DFT) is one of the most frequently used computational tools for studying and predicting the properties of isolated molecules, bulk solids, and material interfaces, including surfaces. Although the theoretical underpinnings of DFT are quite complicated, this book demonstrates that the basic concepts underlying the calculations are simple enough to be understood by anyone with a background in chemistry, physics, engineering, or mathematics. The authors show how the widespread availability of powerful DFT codes makes it possible for students and researchers to apply this important computational technique to a broad range of fundamental and applied problems. Density Functional Theory: A Practical Introduction offers a concise, easy-to-follow introduction to the key concepts and practical applications of DFT, focusing on plane-wave DFT. The authors have many years of experience introducing DFT to studen...

  2. Nanograin densities outside Saturn's A-ring

    CERN Document Server

    Johnson, Robert E; Elrod, Meredith K; Persoon, Ann M

    2016-01-01

    The observed disparity between the radial dependence of the ion and electron densities measured by the Cassini plasma and radio science instruments are used to show that the region between the outer edge of Saturn's main rings and its tenuous G-ring is permeated with small charged grains (nanograins). These grains emanate from the edge of the A-ring and from the tenuous F-ring and G-ring. This is a region of Saturn's magnetosphere that is relatively unexplored, but will be a focus of Cassini's F-ring orbits prior to the end of mission in September 2017. Confirmation of the grain densities predicted here will enhance our ability to describe the formation and destruction of material in this important region of Saturn's magnetosphere.

  3. Hybrid materials offer new perspectives.

    Science.gov (United States)

    Arnetzl, G; Arnetzl, G V

    2015-01-01

    Dental materials, especially in restorative dentistry, must not only be cost-effective, they must also meet many other requirements: biocompatibility, durability, excellent shade and light effects, abrasion resistance, hardness, mechanical strength under pressure, chemical resistance, surface density, ease of manufacture, and easy intraoral maintenance.

  4. Metallic carbon materials

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M.L.; Crespi, V.H.; Louie, S.G.S.; Zettl, A.K.

    1999-11-30

    Novel metallic forms of planar carbon are described, as well as methods of designing and making them. Nonhexagonal arrangements of carbon are introduced into a graphite carbon network essentially without destroying the planar structure. Specifically a form of carbon comprising primarily pentagons and heptagons, and having a large density of states at the Fermi level is described. Other arrangements of pentagons and heptagons that include some hexagons, and structures incorporating squares and octagons are additionally disclosed. Reducing the bond angle symmetry associated with a hexagonal arrangement of carbons increases the likelihood that the carbon material will have a metallic electron structure.

  5. Optical Materials

    Science.gov (United States)

    2014-05-30

    colloidal RL sample was prepared by ultrasonically dispersing the nanoparticles (NP) with the laser dye. For the experiment, the suspension was placed...section and TiO2 nanoparticles (250 nm diameter), optimized upconverted emission was obtained for particle densities of ~2 x 10 9 /cm 3 . A strong...dependence on the nanoparticle concentration and the pumping area was verified. The presence of spikes with linewidths ~ 0.4 nm in the emitted spectrum is

  6. Noise reduction in muon tomography for detecting high density objects

    CERN Document Server

    Benettoni, M; Bonomi, G; Calvagno, G; Calvini, P; Checchia, P; Cortelazzo, G; Cossutta, L; Donzella, A; Furlan, M; Gonella, F; Pegoraro, M; Garola, A Rigoni; Ronchese, P; Squarcia, S; Subieta, M; Vanini, S; Viesti, G; Zanuttigh, P; Zenoni, A; Zumerle, G

    2013-01-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. A new and innovative method is presented in this paper to handle the density fluctuations (noise) of reconstructed images, that are a known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect in short times high density materials, such as lead, when surrounded by light or medium density material. A comparison with algorithms published in literature is also presented.

  7. Noise reduction in muon tomography for detecting high density objects

    Science.gov (United States)

    Benettoni, M.; Bettella, G.; Bonomi, G.; Calvagno, G.; Calvini, P.; Checchia, P.; Cortelazzo, G.; Cossutta, L.; Donzella, A.; Furlan, M.; Gonella, F.; Pegoraro, M.; Rigoni Garola, A.; Ronchese, P.; Squarcia, S.; Subieta, M.; Vanini, S.; Viesti, G.; Zanuttigh, P.; Zenoni, A.; Zumerle, G.

    2013-12-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented.

  8. Vanadium based materials as electrode materials for high performance supercapacitors

    Science.gov (United States)

    Yan, Yan; Li, Bing; Guo, Wei; Pang, Huan; Xue, Huaiguo

    2016-10-01

    As a kind of supercapacitors, pseudocapacitors have attracted wide attention in recent years. The capacitance of the electrochemical capacitors based on pseudocapacitance arises mainly from redox reactions between electrolytes and active materials. These materials usually have several oxidation states for oxidation and reduction. Many research teams have focused on the development of an alternative material for electrochemical capacitors. Many transition metal oxides have been shown to be suitable as electrode materials of electrochemical capacitors. Among them, vanadium based materials are being developed for this purpose. Vanadium based materials are known as one of the best active materials for high power/energy density electrochemical capacitors due to its outstanding specific capacitance and long cycle life, high conductivity and good electrochemical reversibility. There are different kinds of synthetic methods such as sol-gel hydrothermal/solvothermal method, template method, electrospinning method, atomic layer deposition, and electrodeposition method that have been successfully applied to prepare vanadium based electrode materials. In our review, we give an overall summary and evaluation of the recent progress in the research of vanadium based materials for electrochemical capacitors that include synthesis methods, the electrochemical performances of the electrode materials and the devices.

  9. Method for determining transport critical current densities and flux penetration depth in bulk superconductors

    Science.gov (United States)

    Israelsson, Ulf E. (Inventor); Strayer, Donald M. (Inventor)

    1992-01-01

    A contact-less method for determining transport critical current density and flux penetration depth in bulk superconductor material. A compressor having a hollow interior and a plunger for selectively reducing the free space area for distribution of the magnetic flux therein are formed of superconductor material. Analytical relationships, based upon the critical state model, Maxwell's equations and geometrical relationships define transport critical current density and flux penetration depth in terms of the initial trapped magnetic flux density and the ratio between initial and final magnetic flux densities whereby data may be reliably determined by means of the simple test apparatus for evaluating the current density and flux penetration depth.

  10. Iso-geometric shape optimization of magnetic density separators

    OpenAIRE

    2014-01-01

    PurposeThe waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently, a new separator design has been proposed that significantly reduces the required amount of permanent magnet material. The purpose of this paper is to alleviate the undesired end-effects in this design by altering the shape of the ferromagnetic covers of the ...

  11. Interfacial Engineering for Low-Density Graphene Nanocomposites

    Science.gov (United States)

    2014-07-23

    AFRL-OSR-VA-TR-2014-0192 Interfacial engineering for low-density graphene nanocomposites Micah Green TEXAS TECH UNIVERSITY SYSTEM Final Report 07/23...98) v Prescribed by ANSI Std. Z39.18 14-07-2014 Final April 2011 - March 2014 Interfacial engineering for low-density graphene nanocomposites and...several new platforms for graphene-based materials. They examined the use of graphene in polymer nanocomposites , including epoxy films and poly vinyl

  12. Density limits investigation and high density operation in EAST tokamak

    Science.gov (United States)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  13. Atmospheric materiality

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2016-01-01

    A disjunction between the material and the immaterial has been at the heart of the architectural debate for decades. In this dialectic tension, the notion of atmosphere which increasingly claims attention in architectural discourse seems to be parallactic, leading to the re-evaluation of perceptual...... experience and, consequently, to the conceptual and methodological shifts in the production of space, and hence in the way we think about materiality. In this context, architectural space is understood as a contingent construction – a space of engagement that appears to us as a result of continuous...... and complex interferences revealed through our perception; ‘the atmospheric’ is explored as a spatial and affective quality as well as a sensory background, and materiality as a powerful and almost magical agency in shaping of atmosphere. Challenging existing dichotomies and unraveling intrinsic...

  14. Characterization of low density rigid urethane foam

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, F.N.

    1978-10-01

    The chemical and mechanical properties of a low density, rigid polyurethane foam material taken from a Joint Test Assembly (JTA) after 13 years of storage were measured. Chemical analyses confirmed the composition to be Bendix Rigifoam 6003-1.5, a pentaerythritol/epsilon-caprolactone/tolyene diisocyanate polyurethane foam. Comparison of data from testing thermal and mechanical characteristics with data from a currently manufactured foam of identical composition indicates no degradation of properties had occurred. This information gives added confidence to the stockpile lifetime integrity of the Rigifoam 6003-2 foam system designated for use in other programs.

  15. Bonding charge density from atomic perturbations.

    Science.gov (United States)

    Wang, Yi; Wang, William Yi; Chen, Long-Qing; Liu, Zi-Kui

    2015-05-15

    Charge transfer among individual atoms is the key concept in modern electronic theory of chemical bonding. In this work, we present a first-principles approach to calculating the charge transfer. Based on the effects of perturbations of an individual atom or a group of atoms on the electron charge density, we determine unambiguously the amount of electron charge associated with a particular atom or a group of atoms. We computed the topological electron loss versus gain using ethylene, graphene, MgO, and SrTiO3 as examples. Our results verify the nature of chemical bonds in these materials at the atomic level.

  16. Mammographic density estimation with automated volumetric breast density measurement.

    Science.gov (United States)

    Ko, Su Yeon; Kim, Eun-Kyung; Kim, Min Jung; Moon, Hee Jung

    2014-01-01

    To compare automated volumetric breast density measurement (VBDM) with radiologists' evaluations based on the Breast Imaging Reporting and Data System (BI-RADS), and to identify the factors associated with technical failure of VBDM. In this study, 1129 women aged 19-82 years who underwent mammography from December 2011 to January 2012 were included. Breast density evaluations by radiologists based on BI-RADS and by VBDM (Volpara Version 1.5.1) were compared. The agreement in interpreting breast density between radiologists and VBDM was determined based on four density grades (D1, D2, D3, and D4) and a binary classification of fatty (D1-2) vs. dense (D3-4) breast using kappa statistics. The association between technical failure of VBDM and patient age, total breast volume, fibroglandular tissue volume, history of partial mastectomy, the frequency of mass > 3 cm, and breast density was analyzed. The agreement between breast density evaluations by radiologists and VBDM was fair (k value = 0.26) when the four density grades (D1/D2/D3/D4) were used and moderate (k value = 0.47) for the binary classification (D1-2/D3-4). Twenty-seven women (2.4%) showed failure of VBDM. Small total breast volume, history of partial mastectomy, and high breast density were significantly associated with technical failure of VBDM (p = 0.001 to 0.015). There is fair or moderate agreement in breast density evaluation between radiologists and VBDM. Technical failure of VBDM may be related to small total breast volume, a history of partial mastectomy, and high breast density.

  17. Mammography density estimation with automated volumetic breast density measurement

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Su Yeon; Kim, Eun Kyung; Kim, Min Jung; Moon, Hee Jung [Dept. of Radiology, Severance Hospital, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2014-06-15

    To compare automated volumetric breast density measurement (VBDM) with radiologists' evaluations based on the Breast Imaging Reporting and Data System (BI-RADS), and to identify the factors associated with technical failure of VBDM. In this study, 1129 women aged 19-82 years who underwent mammography from December 2011 to January 2012 were included. Breast density evaluations by radiologists based on BI-RADS and by VBDM (Volpara Version 1.5.1) were compared. The agreement in interpreting breast density between radiologists and VBDM was determined based on four density grades (D1, D2, D3, and D4) and a binary classification of fatty (D1-2) vs. dense (D3-4) breast using kappa statistics. The association between technical failure of VBDM and patient age, total breast volume, fibroglandular tissue volume, history of partial mastectomy, the frequency of mass > 3 cm, and breast density was analyzed. The agreement between breast density evaluations by radiologists and VBDM was fair (k value = 0.26) when the four density grades (D1/D2/D3/D4) were used and moderate (k value = 0.47) for the binary classification (D1-2/D3-4). Twenty-seven women (2.4%) showed failure of VBDM. Small total breast volume, history of partial mastectomy, and high breast density were significantly associated with technical failure of VBDM (p 0.001 to 0.015). There is fair or moderate agreement in breast density evaluation between radiologists and VBDM. Technical failure of VBDM may be related to small total breast volume, a history of partial mastectomy, and high breast density.

  18. Utopian Materialities

    DEFF Research Database (Denmark)

    Elgaard-Jensen, Torben

    2004-01-01

    In various ways, this paper makes the counter-intuitive claim that the utopian and the material are thoroughlyinterdependent, rather than worlds apart. First, through a reading of Thomas More's Utopia, it is argued thatUtopia is the product of particular kinds of relations, rather than merely...... a detachment from the known world.Second, the utopianism of a new economy firm is examined. It is argued that the physical set-up of the firm -in particular the distribution of tables and chairs - evoke a number of alternatives to ordinary work practice.In this way the materialities of the firm are crucial...

  19. Electronic materials

    CERN Document Server

    Kwok, H L

    2010-01-01

    The electronic properties of solids have become of increasing importance in the age of information technology. The study of solids and materials, while having originated from the disciplines of physics and chemistry, has evolved independently over the past few decades. The classical treatment of solid-state physics, which emphasized classifications, theories and fundamental physical principles, is no longer able to bridge the gap between materials advances and applications. In particular, the more recent developments in device physics and technology have not necessarily been driven by new conc

  20. Density Functional Theory An Advanced Course

    CERN Document Server

    Dreizler, Reiner M

    2011-01-01

    Density Functional Theory (DFT) has firmly established itself as the workhorse for the atomic-level simulation of condensed matter phases, pure or composite materials and quantum chemical systems. The present book is a rigorous and detailed introduction to the foundations up to and including such advanced topics as orbital-dependent functionals and both time-dependent and relativistic DFT. Given the many ramifications of contemporary DFT, this text concentrates on the self-contained presentation of the basics of the most widely used DFT variants. This implies a thorough discussion of the corresponding existence theorems and effective single particle equations, as well as of key approximations utilized in implementations. The formal results are complemented by selected quantitative results, which primarily aim at illustrating strengths and weaknesses of a particular approach or functional. DFT for superconducting or nuclear and hadronic systems are not addressed in this work. The structure and material contain...

  1. Measurement and analyses of molten Ni-Co alloy density

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; K. MUKAI; FANG Liang; FU Ya; YANG Ren-hui

    2006-01-01

    With the advent of powerful mathematical modeling techniques for material phenomena, there is renewed interest in reliable data for the density of the Ni-based superalloys. Up to now, there has been few report on the density of molten Ni-Co alloy.In order to obtain more accurate density data for molten Ni-Co alloy, the density of molten Ni-Co alloy was measured with a modified sessile drop method, and the accommodation of different atoms in molten Ni-Co alloy was analyzed. The density of alloy is found to decrease with increasing temperature and Co concentration in the alloy. The molar volume of molten Ni-Co alloy increases with increasing Co concentration. The molar volume of Ni-Co alloy determined shows a positive deviation from the linear molar volume, and the deviation of molar volume from ideal mixing increases with increasing Co concentration over the experimental concentration range.

  2. Emerging Materiality

    DEFF Research Database (Denmark)

    Bertelsen, Olav Wedege; Breinbjerg, Morten; Pold, Søren

    2009-01-01

    The authors examine how materiality emerges from complex chains of mediation in creative software use. The primarily theoretical argument is inspired and illustrated by interviews with two composers of electronic music. The authors argue that computer mediated activity should not primarily...

  3. Touching Materiality

    DEFF Research Database (Denmark)

    Rasmussen, Lisa Rosén

    2012-01-01

    Dripping ink pens, colourful paint on skin, vegetables pots on a school roof. In interviews with three generations of former school pupils, memories of material objects bore a relation to everyday school life in the past. Interwoven, these objects entered the memorising processes, taking...

  4. Combined backscatter and transmission method for nuclear density gauge

    Directory of Open Access Journals (Sweden)

    Golgoun Seyed Mohammad

    2015-01-01

    Full Text Available Nowadays, the use of nuclear density gauges, due to the ability to work in harsh industrial environments, is very common. In this study, to reduce error related to the ρ of continuous measuring density, the combination of backscatter and transmission are used simultaneously. For this reason, a 137Cs source for Compton scattering dominance and two detectors are simulated by MCNP4C code for measuring the density of 3 materials. Important advantages of this combined radiometric gauge are diminished influence of μ and therefore improving linear regression.

  5. All Road Density (18km)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Density (km / km^2) of all roads in the western United States. Dataset was developed to generalize the 2000 US Census TIGER/Line Roads layer to a density within 18km...

  6. Space, Density and Urban Form

    NARCIS (Netherlands)

    Berghauser Pont, M.Y.; Haupt, P.A.

    2009-01-01

    The concentration of humans – in some cases judged as too high, in others not high enough – and the problems connected to this, have resulted in discussions on density. Prior to the 20th century, density in European cities was merely an outcome of complex circumstances. During the second half of the

  7. The Density of Sustainable Settlements

    DEFF Research Database (Denmark)

    Lauring, Michael; Silva, Victor; Jensen, Ole B.

    2010-01-01

    This paper is the initial result of a cross-disciplinary attempt to encircle an answer to the question of optimal densities of sustainable settlements. Urban density is an important component in the framework of sustainable development and influences not only the character and design of cities...

  8. The Density of Sustainable Settlements

    DEFF Research Database (Denmark)

    Lauring, Michael; Silva, Victor; Jensen, Ole B.;

    2010-01-01

    This paper is the initial result of a cross-disciplinary attempt to encircle an answer to the question of optimal densities of sustainable settlements. Urban density is an important component in the framework of sustainable development and influences not only the character and design of cities...

  9. Effect of High-K Dielectric Materials on Leakage Current

    OpenAIRE

    Puneet Kundu; Rekha Yadav

    2012-01-01

    In this paper, a comparative study of different high-k dielectric materials based on tunneling current density has been deployed. The various types of high-k dielectric materials such as aluminium oxide, hafnium oxide, silicon nitride are compared using Schrödinger equation. The analytical model of tunneling current density has been computed using WKB approximation method. The simulation results of various high-k dielectric materials have also been computed. Different high-k dielectric materi...

  10. LEGO Materials.

    Science.gov (United States)

    Talapin, Dmitri V

    2008-06-01

    Two papers in this issue report important developments in the field of inorganic nanomaterials. Chen and O'Brien discuss self-assembly of semiconductor nanocrystals into binary nanoparticle superlattices (BNSLs). They show that simple geometrical principles based on maximizing the packing density can determine BNSL symmetry in the absence of cohesive electrostatic interactions. This finding highlights the role of entropy as the driving force for ordering nanoparticles. The other paper, by Weller and co-workers, addresses an important problem related to device integration of nanoparticle assemblies. They employ the Langmuir-Blodgett technique to prepare long-range ordered monolayers of close-packed nanocrystals and transfer them to different substrates.

  11. Local doping of two-dimensional materials

    Science.gov (United States)

    Wong, Dillon; Velasco, Jr, Jairo; Ju, Long; Kahn, Salman; Lee, Juwon; Germany, Chad E.; Zettl, Alexander K.; Wang, Feng; Crommie, Michael F.

    2016-09-20

    This disclosure provides systems, methods, and apparatus related to locally doping two-dimensional (2D) materials. In one aspect, an assembly including a substrate, a first insulator disposed on the substrate, a second insulator disposed on the first insulator, and a 2D material disposed on the second insulator is formed. A first voltage is applied between the 2D material and the substrate. With the first voltage applied between the 2D material and the substrate, a second voltage is applied between the 2D material and a probe positioned proximate the 2D material. The second voltage between the 2D material and the probe is removed. The first voltage between the 2D material and the substrate is removed. A portion of the 2D material proximate the probe when the second voltage was applied has a different electron density compared to a remainder of the 2D material.

  12. Aspects of unconventional density waves

    Science.gov (United States)

    Maki, Kazumi; Dóra, Balázs; Virosztek, Attila

    2003-12-01

    Recently many people discuss unconventional density waves (i.e. unconventional charge density waves (UCDW) and unconventional spin density waves (USDW)). Unlike in conventional density waves, the quasiparticle spectrum in these systems is gapless. Also these systems remain metallic. Indeed it appears that there are many candidates for UDW. The low temperature phase of α-(BEDT-TTF)2KHg(SCN)4, the antiferromagnetic phase in URu2Si2, the CDW in transition metal dichalcogenite NbSe2, the pseudogap phase in high Tc cuprate superconductors, the glassy phase in organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br. After a brief introduction on UCDW and USDW, we shall discuss some of the above systems, where we believe we have evidence for unconventional density waves.

  13. Detecting density variations and nanovoids.

    Science.gov (United States)

    Miller, M K; Longstreth-Spoor, L; Kelton, K F

    2011-05-01

    A combination of simulated and experimental data has been used to investigate the size range of nanovoids that can be detected in atom probe tomography data. Simulated atom probe tomography data have revealed that nanovoids as small as 1 nm in diameter can be detected in atom probe tomography data with the use of iso-density surfaces. Iso-density surfaces may be used to quantify the size, morphology and number density of nanovoids and other variations in density in atom probe tomography data. Experimental data from an aluminum-yttrium-iron metallic glass ribbon have revealed the effectiveness of this approach. Combining iso-density surfaces with atom maps also permits the segregation of solute to the nanovoids to be investigated. Field ion microscopy and thin section atom maps have also been used to detect pores and larger voids. Published by Elsevier B.V.

  14. Friction Material Composites Materials Perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  15. Flash sintering of ceramic materials

    Science.gov (United States)

    Dancer, C. E. J.

    2016-10-01

    During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sintering methods carried out to date, and compares the properties of the materials obtained to those produced by conventional sintering. The flash sintering process is described for oxides of zirconium, yttrium, aluminium, tin, zinc, and titanium; silicon and boron carbide, zirconium diboride, materials for solid oxide fuel applications, ferroelectric materials, and composite materials. While experimental observations have been made on a wide range of materials, understanding of the underlying mechanisms responsible for the onset and latter stages of flash sintering is still elusive. Elements of the proposed theories to explain the observed behaviour include extensive Joule heating throughout the material causing thermal runaway, arrested by the current limitation in the power supply, and the formation of defect avalanches which rapidly and dramatically increase the sample conductivity. Undoubtedly, the flash sintering process is affected by the electric field strength, furnace temperature and current density limit, but also by microstructural features such as the presence of second phase particles or dopants and the particle size in the starting material. While further experimental work and modelling is still required to attain a full understanding capable of predicting the success of the flash sintering process in different materials, the technique non-etheless holds great potential for exceptional control of the ceramic sintering process.

  16. Electrical energy storage and dissipation in materials

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Xiaoyu, E-mail: zheng@math.kent.edu [Department of Mathematical Sciences, Kent State University, Kent, OH 44242 (United States); Palffy-Muhoray, Peter [Liquid Crystal Institute, Kent State University, Kent, OH 44242 (United States)

    2015-09-18

    Using a simple classical approach, we consider where and how electrical energy is stored in lossy dispersive materials. We argue that the material contribution to the electrical energy density is simply the sum of the kinetic and potential energies of the charges present under the influence of the applied electric field. It follows that the stored energy density must be positive. We provide simple expressions for the stored and dissipated energy densities; in the lossless case, our expressions reduce to the standard results of Brillouin and Landau.

  17. High Energy Density aluminum/oxygen cell

    Science.gov (United States)

    Rudd, E. J.; Gibbons, D. W.

    An alternative to a secondary battery as the power source for vehicle propulsion is a fuel cell, an example of which is the metal/air cell using metals such as aluminum, zinc, or iron. Aluminum is a particularly attractive candidate, with high energy and power densities, environmentally acceptable and having a large, established industrial base for production and distribution. An aluminum/oxygen system is currently under development for a prototype unmanned, undersea vehicle (UUV) for the US navy and recent work has focussed upon low corrosion aluminum alloys, and an electrolyte management system for processing the by-products of the energy-producing reactions. This paper summarizes the progress made in both areas. Anode materials capable of providing high utilization factors over current densities ranging from 5 to 150 mA/cm 2 have been identified, such materials being essential to realize mission life for the UUV. With respect to the electrolyte management system, a filter/precipitator unit has been successfully operated for over 250 h in a large scale, half-cell system.

  18. Density of States for Warped Energy Bands

    Science.gov (United States)

    Mecholsky, Nicholas A.; Resca, Lorenzo; Pegg, Ian L.; Fornari, Marco

    2016-02-01

    Warping of energy bands can affect the density of states (DOS) in ways that can be large or subtle. Despite their potential for significant practical impacts on materials properties, these effects have not been rigorously demonstrated previously. Here we rectify this using an angular effective mass formalism that we have developed. To clarify the often confusing terminology in this field, “band warping” is precisely defined as pertaining to any multivariate energy function E(k) that does not admit a second-order differential at an isolated critical point in k-space, which we clearly distinguish from band non-parabolicity. We further describe band “corrugation” as a qualitative form of band warping that increasingly deviates from being twice differentiable at an isolated critical point. These features affect the density-of-states and other parameters ascribed to band warping in various ways. We demonstrate these effects, providing explicit calculations of DOS and their effective masses for warped energy dispersions originally derived by Kittel and others. Other physical and mathematical examples are provided to demonstrate fundamental distinctions that must be drawn between DOS contributions that originate from band warping and contributions that derive from band non-parabolicity. For some non-degenerate bands in thermoelectric materials, this may have profound consequences of practical interest.

  19. Magnetocaloric materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeppesen, Stinus

    2008-10-15

    New and improved magnetocaloric materials are one of the cornerstones in the development of room temperature magnetic refrigeration. Magnetic refrigeration has been used since the 1930ies in cryogenic applications, but has since the discovery of room temperature refrigerants received enormous attention. This Ph.D. work has been mainly concerned with developing a new technique to characterize the magnetocaloric effect (MCE) and using this technique in the investigations on new and improved magnetocaloric materials. For this purpose a novel differential scanning calorimeter (DSC) with applied magnetic fields was developed for measuring heat capacity as function of magnetic field. Measurements using the developed DSC demonstrate a very high sensitivity, fast measurements and good agreement with results obtained by other techniques. Furthermore, two material systems have been described in this work. Both systems take basis in the mixed-valence manganite system La{sub 1-x}Ca{sub x}MnO{sub 3} well known from research on colossal magnetoresistance (CMR). The mixed-valence manganite crystallizes in the perovskite structure of general formula ABO{sub 3}. The first material system is designed to investigate the influence of low level Cu doping on the B-site. Six different samples were prepared with over-stoichiometric compositions La{sub 0.67}Ca{sub 0.33}Mn{sub 1.05}Cu{sub x}O{sub 3}, x=0, 1, 2, 3, 4 and 5%. All compositions crystallized well in the same perovskite structure, but the morphology of the samples changed drastically with doping. Investigation on the magnetocaloric properties revealed that small levels of Cu up to around 3% could improve the magnetocaloric performance of the materials. Furthermore, Cu could be used to tune the temperature interval without deteriorating the MCE, which is a much desired characteristic for potential use in magnetic refrigerators. A less comprehensive part of the work has been concerned with the investigation of doping on the A

  20. DENTAL MATERIALS.

    Science.gov (United States)

    The study deals with the determination of characteristic physical and mechanical properties of restorative dental materials, and effect of...manipulative variables on these properties. From the study an entirely new dental gold inlay casting technic was developed, based on the principle of...controlled water added hygroscopic technic. The method has had successful dental applications and is a recognized method of dental inlay casting procedure

  1. Strategic Materials

    Science.gov (United States)

    2007-01-01

    Titanium exists primarily in the minerals anatase , brookite, ilmenite, perovskite, rutile , titanite (sphene), as well in many iron ores. Of these minerals...raw materials ( anatase , ilmenite, and rutile ) are estimated at over 2 billion tons (U.S.G.S., 2007, p. 175). Due to its tendency to react with air at...only rutile (titanium dioxide) and ilmenite (iron-titanium oxide) have any economic importance. Unfortunately, high concentrations of the mineral

  2. Biomedical Materials

    Institute of Scientific and Technical Information of China (English)

    CHANG Jiang; ZHOU Yanling

    2011-01-01

    @@ Biomedical materials, biomaterials for short, is regarded as "any substance or combination of substances, synthetic or natural in origin, which can be used for any period of time, as a whole or as part of a system which treats, augments, or replaces any tissue, organ or function of the body" (Vonrecum & Laberge, 1995).Biomaterials can save lives, relieve suffering and enhance the quality of life for human being.

  3. Material monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kotter, W.; Zirker, L.; Hancock, J.A.

    1995-11-01

    Waste Reduction Operations Complex (WROC) facilities are located at the Idaho National Engineering Laboratory (INEL). The overall goal for the Pollution Prevention/Waste Minimization Unit is to identify and establish the correct amount of waste generated so that it can be reduced. Quarterly, the INEL Pollution Prevention (P2) Unit compares the projected amount of waste generated per process with the actual amount generated. Examples of waste streams that would be addresses for our facility would include be are not limited to: Maintenance, Upgrades, Office and Scrap Metal. There are three potential sources of this variance: inaccurate identification of those who generate the waste; inaccurate identification of the process that generates the waste; and inaccurate measurement of the actual amount generated. The Materials Monitoring Program was proposed to identify the sources of variance and reduce the variance to an acceptable level. Prior to the implementation of the Material Monitoring Program, all information that was gathered and recorded was done so through an informal estimation of waste generated by various personnel concerned with each processes. Due to the inaccuracy of the prior information gathering system, the Material Monitoring Program was established. The heart of this program consists of two main parts. In the first part potential waste generators provide information on projected waste generation process. In the second part, Maintenance, Office, Scrap Metal and Facility Upgrade wastes from given processes is disposed within the appropriate bin dedicated to that process. The Material Monitoring Program allows for the more accurate gathering of information on the various waste types that are being generated quarterly.

  4. A Density Functional Theory Study

    KAUST Repository

    Lim, XiaoZhi

    2011-12-11

    Complexes with pincer ligand moieties have garnered much attention in the past few decades. They have been shown to be highly active catalysts in several known transition metal-catalyzed organic reactions as well as some unprecedented organic transformations. At the same time, the use of computational organometallic chemistry to aid in the understanding of the mechanisms in organometallic catalysis for the development of improved catalysts is on the rise. While it was common in earlier studies to reduce computational cost by truncating donor group substituents on complexes such as tertbutyl or isopropyl groups to hydrogen or methyl groups, recent advancements in the processing capabilities of computer clusters and codes have streamlined the time required for calculations. As the full modeling of complexes become increasingly popular, a commonly overlooked aspect, especially in the case of complexes bearing isopropyl substituents, is the conformational analysis of complexes. Isopropyl groups generate a different conformer with each 120 ° rotation (rotamer), and it has been found that each rotamer typically resides in its own potential energy well in density functional theory studies. As a result, it can be challenging to select the most appropriate structure for a theoretical study, as the adjustment of isopropyl substituents from a higher-energy rotamer to the lowest-energy rotamer usually does not occur during structure optimization. In this report, the influence of the arrangement of isopropyl substituents in pincer complexes on calculated complex structure energies as well as a case study on the mechanism of the isomerization of an iPrPCP-Fe complex is covered. It was found that as many as 324 rotamers can be generated for a single complex, as in the case of an iPrPCP-Ni formato complex, with the energy difference between the global minimum and the highest local minimum being as large as 16.5 kcalmol-1. In the isomerization of a iPrPCP-Fe complex, it was found

  5. Constitutive models based on dislocation density:formulation and implementation into finite element codes

    OpenAIRE

    Domkin, Konstantin

    2005-01-01

    Correct description of the material behaviour is an extra challenge in simulation of the materials processing and manufacturing processes such as metal forming. Material models must account for varying strain, strain rate and temperature, and changing microstructure. This study is devoted to the physically based models of metal plasticity - dislocation density models, their numerical implementation and parameter identification. The basic concepts of dislocation density modelling are introduce...

  6. Electron and Positron Stopping Powers of Materials

    Science.gov (United States)

    SRD 7 NIST Electron and Positron Stopping Powers of Materials (PC database for purchase)   The EPSTAR database provides rapid calculations of stopping powers (collisional, radiative, and total), CSDA ranges, radiation yields and density effect corrections for incident electrons or positrons with kinetic energies from 1 keV to 10 GeV, and for any chemically defined target material.

  7. Density fluctuations in traffic flow

    CERN Document Server

    Yukawa, S

    1996-01-01

    Density fluctuations in traffic current are studied by computer simulations using the deterministic coupled map lattice model on a closed single-lane circuit. By calculating a power spectral density of temporal density fluctuations at a local section, we find a power-law behavior, \\sim 1/f^{1.8}, on the frequency f, in non-congested flow phase. The distribution of the headway distance h also shows the power law like \\sim 1/h^{3.0} at the same time. The power law fluctuations are destroyed by the occurence of the traffic jam.

  8. Breakup Densities of Hot Nuclei.

    Science.gov (United States)

    Viola, Vic

    2006-04-01

    Breakup densities of hot ^197Au-like residues have been deduced from the systematic trends of Coulomb parameters required to fit intermediate-mass-fragment kinetic-energy spectra. The results indicate emission from nuclei near normal nuclear density below an excitation energy E*/A .3ex˜x 5 MeV. Temperatures derived from these data with a density-dependent Fermi-gas model yield a nuclear caloric curve that is generally consistent with those derived from isotope ratios.

  9. Density perturbations with relativistic thermodynamics

    CERN Document Server

    Maartens, R

    1997-01-01

    We investigate cosmological density perturbations in a covariant and gauge- invariant formalism, incorporating relativistic causal thermodynamics to give a self-consistent description. The gradient of density inhomogeneities splits covariantly into a scalar part, a rotational vector part that is determined by the vorticity, and a tensor part that describes the shape. We give the evolution equations for these parts in the general dissipative case. Causal thermodynamics gives evolution equations for viswcous stress and heat flux, which are coupled to the density perturbation equation and to the entropy and temperature perturbation equations. We give the full coupled system in the general dissipative case, and simplify the system in certain cases.

  10. FOREWORD: Materials metrology Materials metrology

    Science.gov (United States)

    Bennett, Seton; Valdés, Joaquin

    2010-04-01

    It seems that so much of modern life is defined by the materials we use. From aircraft to architecture, from cars to communications, from microelectronics to medicine, the development of new materials and the innovative application of existing ones have underpinned the technological advances that have transformed the way we live, work and play. Recognizing the need for a sound technical basis for drafting codes of practice and specifications for advanced materials, the governments of countries of the Economic Summit (G7) and the European Commission signed a Memorandum of Understanding in 1982 to establish the Versailles Project on Advanced Materials and Standards (VAMAS). This project supports international trade by enabling scientific collaboration as a precursor to the drafting of standards. The VAMAS participants recognized the importance of agreeing a reliable, universally accepted basis for the traceability of the measurements on which standards depend for their preparation and implementation. Seeing the need to involve the wider metrology community, VAMAS approached the Comité International des Poids et Mesures (CIPM). Following discussions with NMI Directors and a workshop at the BIPM in February 2005, the CIPM decided to establish an ad hoc Working Group on the metrology applicable to the measurement of material properties. The Working Group presented its conclusions to the CIPM in October 2007 and published its final report in 2008, leading to the signature of a Memorandum of Understanding between VAMAS and the BIPM. This MoU recognizes the work that is already going on in VAMAS as well as in the Consultative Committees of the CIPM and establishes a framework for an ongoing dialogue on issues of materials metrology. The question of what is meant by traceability in the metrology of the properties of materials is particularly vexed when the measurement results depend on a specified procedure. In these cases, confidence in results requires not only traceable

  11. A Model of Foam Density Prediction for Expanded Perlite Composites

    Directory of Open Access Journals (Sweden)

    Arifuzzaman Md

    2015-01-01

    Full Text Available Multiple sets of variables associated with expanded perlite particle consolidation in foam manufacturing were analyzed to develop a model for predicting perlite foam density. The consolidation of perlite particles based on the flotation method and compaction involves numerous variables leading to the final perlite foam density. The variables include binder content, compaction ratio, perlite particle size, various perlite particle densities and porosities, and various volumes of perlite at different stages of process. The developed model was found to be useful not only for prediction of foam density but also for optimization between compaction ratio and binder content to achieve a desired density. Experimental verification was conducted using a range of foam densities (0.15 – 0.5 g/cm3 produced with a range of compaction ratios (1.5 – 3.5, a range of sodium silicate contents (0.05 – 0.35 g/ml in dilution, a range of expanded perlite particle sizes (1 – 4 mm, and various perlite densities (such as skeletal, material, bulk, and envelope densities. A close agreement between predictions and experimental results was found.

  12. Lightweight hydride storage materials

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, G.J.; Guthrie, S.E.; Bauer, W. [Sandia National Labs., Livermore, CA (United States)

    1995-09-01

    The need for lightweight hydrides in vehicular applications has prompted considerable research into the use of magnesium and its alloys. Although this earlier work has provided some improved performance in operating temperature and pressure, substantial improvements are needed before these materials will significantly enhance the performance of an engineered system on a vehicle. We are extending the work of previous investigators on Mg alloys to reduce the operating temperature and hydride heat of formation in light weight materials. Two important results will be discussed in this paper: (1) a promising new alloy hydride was found which has better pressure-temperature characteristics than any previous Mg alloy and, (2) a new fabrication process for existing Mg alloys was developed and demonstrated. The new alloy hydride is composed of magnesium, aluminum and nickel. It has an equilibrium hydrogen overpressure of 1.3 atm. at 200{degrees}C and a storage capacity between 3 and 4 wt.% hydrogen. A hydrogen release rate of approximately 5 x 10{sup -4} moles-H{sub 2}/gm-min was measured at 200{degrees}C. The hydride heat of formation was found to be 13.5 - 14 kcal/mole-H{sub 2}, somewhat lower than Mg{sub 2}Ni. The new fabrication method takes advantage of the high vapor transport of magnesium. It was found that Mg{sub 2}Ni produced by our low temperature process was better than conventional materials because it was single phase (no Mg phase) and could be fabricated with very small particle sizes. Hydride measurements on this material showed faster kinetic response than conventional material. The technique could potentially be applied to in-situ hydride bed fabrication with improved packing density, release kinetics, thermal properties and mechanical stability.

  13. Manufacturing technology of the composite materials: nanocrystalline material – polymer type

    OpenAIRE

    B. Ziębowicz; D. Szewieczek; L.A. Dobrzański

    2005-01-01

    Purpose: This paper presents the material and technological solution which makes it possible to obtain the nanocrystalline, ferromagnetic powder material of Fe73.5Cu1Nb3Si13.5B9 alloy after its thermal nanocrystallization with the succeeding high-energy milling. Another aspect was to develop the technology to obtain the nanocrystalline composite materials made by binding the obtained powder material with the high density low-pressures polyethylene (PEHD) with the controlled ferromagnetic and ...

  14. High Energy Density Capacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA?s future space science missions cannot be realized without the state of the art energy storage devices which require high energy density, high reliability, and...

  15. Density functionals from deep learning

    CERN Document Server

    McMahon, Jeffrey M

    2016-01-01

    Density-functional theory is a formally exact description of a many-body quantum system in terms of its density; in practice, however, approximations to the universal density functional are required. In this work, a model based on deep learning is developed to approximate this functional. Deep learning allows computational models that are capable of naturally discovering intricate structure in large and/or high-dimensional data sets, with multiple levels of abstraction. As no assumptions are made as to the form of this structure, this approach is much more powerful and flexible than traditional approaches. As an example application, the model is shown to perform well on approximating the kinetic-energy density functional for noninteracting electrons. The model is analyzed in detail, and its advantages over conventional machine learning are discussed.

  16. Adiabatic density surface, neutral density surface, potential density surface, and mixing path

    Institute of Scientific and Technical Information of China (English)

    HUANG Rui-xin

    2014-01-01

    In this paper, adiabatic density surface, neutral density surface and potential density surface are compared. The adiabatic density surface is defined as the surface on which a water parcellcan move adiabatically, without changing its potential temperature and salinity. For a water parcelltaken at a given station and pressure level, the corresponding adiabatic density surface can be determined through simple calculations. This family of surface is neutrally buoyant in the world ocean, and different from other surfaces that are not truly neutrally buoyant. In order to explore mixing path in the ocean, a mixing ratio m is introduced, which is defined as the portion of potential temperature and salinity of a water parcellthat has exchanged with the environment during a segment of migration in the ocean. Two extreme situations of mixing path in the ocean are m=0 (no mixing), which is represented by the adiabatic density curve, and m=1, where the original information is completely lost through mixing. The latter is represented by the neutral density curve. The reality lies in between, namely, 0

  17. Primordial density and BAO reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Chen, Xuelei

    2016-01-01

    We present a new method to reconstruct the primordial (linear) density field using the estimated nonlinear displacement field. The divergence of the displacement field gives the reconstructed density field. We solve the nonlinear displacement field in the 1D cosmology and show the reconstruction results. The new reconstruction algorithm recovers a lot of linear modes and reduces the nonlinear damping scale significantly. The successful 1D reconstruction results imply the new algorithm should also be a promising technique in the 3D case.

  18. Parallel Multiscale Autoregressive Density Estimation

    OpenAIRE

    Reed, Scott; Oord, Aäron van den; Kalchbrenner, Nal; Colmenarejo, Sergio Gómez; Wang, Ziyu; Belov, Dan; de Freitas, Nando

    2017-01-01

    PixelCNN achieves state-of-the-art results in density estimation for natural images. Although training is fast, inference is costly, requiring one network evaluation per pixel; O(N) for N pixels. This can be sped up by caching activations, but still involves generating each pixel sequentially. In this work, we propose a parallelized PixelCNN that allows more efficient inference by modeling certain pixel groups as conditionally independent. Our new PixelCNN model achieves competitive density e...

  19. Casting materials

    Energy Technology Data Exchange (ETDEWEB)

    Chaudhry, Anil R. (Xenia, OH); Dzugan, Robert (Cincinnati, OH); Harrington, Richard M. (Cincinnati, OH); Neece, Faurice D. (Lyndurst, OH); Singh, Nipendra P. (Pepper Pike, OH)

    2011-06-14

    A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

  20. Energy materials

    CERN Document Server

    Bruce, Duncan W; Walton, Richard I

    2011-01-01

    In an age of global industrialisation and population growth, the area of energy is one that is very much in the public consciousness. Fundamental scientific research is recognised as being crucial to delivering solutions to these issues, particularly to yield novel means of providing efficient, ideally recyclable, ways of converting, transporting and delivering energy. This volume considers a selection of the state-of-the-art materials that are being designed to meet some of the energy challenges we face today. Topics are carefully chosen that show how the skill of the synthetic chemist can

  1. Materializing Superghosts

    CERN Document Server

    Alexandrov, Victor; Losev, Andrei; Lysov, Vyacheslav

    2007-01-01

    We construct the off-shell BV realization of N=1, d=10 SYM with 7 auxillary fields. This becomes possible due to materialized ghost phenomenon. Namely, supersymmetry ghosts are coordinates on a manifold B of 10-dimensional spinors with pure spinors cut out. Auxillary fields are sections of a bundle over B, and supersymmetry transformations are nonlinear in ghosts. By integrating out axillary fields we obtain on-shell supersymmetric BV action with terms quadratic in antifields. Exactly this on-shell BV action was obtained in our previous paper after integration out of auxiliary fields in the framework of Pure Spinor Superfield Formalism.

  2. Construction material

    Science.gov (United States)

    Wagh, Arun S.; Antink, Allison L.

    2008-07-22

    A structural material of a polystyrene base and the reaction product of the polystyrene base and a solid phosphate ceramic is applied as a slurry which includes one or more of a metal oxide or a metal hydroxide with a source of phosphate to produce a phosphate ceramic and a poly (acrylic acid or acrylate) or combinations or salts thereof and polystyrene or MgO applied to the polystyrene base and allowed to cure so that the dried aqueous slurry chemically bonds to the polystyrene base. A method is also disclosed of applying the slurry to the polystyrene base.

  3. High Thermal Conductivity Materials

    CERN Document Server

    Shinde, Subhash L

    2006-01-01

    Thermal management has become a ‘hot’ field in recent years due to a need to obtain high performance levels in many devices used in such diverse areas as space science, mainframe and desktop computers, optoelectronics and even Formula One racing cars! Thermal solutions require not just taking care of very high thermal flux, but also ‘hot spots’, where the flux densities can exceed 200 W/cm2. High thermal conductivity materials play an important role in addressing thermal management issues. This volume provides readers a basic understanding of the thermal conduction mechanisms in these materials and discusses how the thermal conductivity may be related to their crystal structures as well as microstructures developed as a result of their processing history. The techniques for accurate measurement of these properties on large as well as small scales have been reviewed. Detailed information on the thermal conductivity of diverse materials including aluminum nitride (AlN), silicon carbide (SiC), diamond, a...

  4. Density-Decomposed Orbital-Free Density Functional Theory for Covalent Systems and Application to Li-Si alloys

    Science.gov (United States)

    Xia, Junchao; Carter, Emily

    2014-03-01

    We propose a density decomposition scheme using a Wang-Govind-Carter (WGC)-based kinetic energy density functional (KEDF) to accurately and efficiently simulate covalent systems within orbital-free (OF) density functional theory (DFT). By using a local, density-dependent scale function, the total density is decomposed into a localized density within covalent bond regions and a flattened delocalized density, with the former described by semilocal KEDFs and the latter treated by the WGC KEDF. The new model predicts reasonable equilibrium volumes, bulk moduli, and phase ordering energies for various semiconductors compared to Kohn-Sham (KS) DFT benchmarks. The surface energy of Si(100) also agrees well with KSDFT. We further apply the model to study mechanical properties of Li-Si alloys, which have been recently recognized as a promising candidate for next-generation anodes of Li-ion batteries with outstanding capacity. We study multiple crystalline Li-Si alloys. The WGCD KEDF predicts accurate cell lattice vectors, equilibrium volumes, elastic moduli, electron densities, alloy formation and Li adsorption energies. Because of its quasilinear scaling, coupled with the level of accuracy shown here, OFDFT appears quite promising for large-scale simulation of such materials phenomena. Office of Naval Research, National Science Foundation, Tigress High Performance Computing Center.

  5. Relationship between mass density, electron density, and elemental composition of body tissues for Monte Carlo simulation in radiation treatment planning

    CERN Document Server

    Kanematsu, Nobuyuki

    2015-01-01

    Purpose: For Monte Carlo simulation of radiotherapy, x-ray CT number of every system needs to be calibrated and converted to mass density and elemental composition. This study aims to formulate material properties of body tissues for practical two-step conversion from CT number. Methods: We used the latest compilation on body tissues that constitute reference adult male and female. We formulated the relations among mass, electron, and elemental densities into polylines to connect representative tissues, for which we took mass-weighted mean for the tissues in limited density regions. We compared the polyline functions of mass density with a bi-line for electron density and broken lines for elemental densities, which were derived from preceding studies. Results: There was generally high correlation between mass density and the other densities except of C, N, and O for light spongiosa tissues occupying 1% of body mass. The polylines fitted to the dominant tissues and were generally consistent with the bi-line an...

  6. Modeling pyrolysis of charring material in fire

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A modified model of pyrolysis for charring materials in fire has been proposed in this note. In this model some special factors which show the effect on pyrolysis are considered, i.e. heat loss by convection and radiation caused by surface temperature rise and shrinkage of char surface are considered. Experimental device is designed specially for validating the reliability of the model. Effects of density of materials and heat radiation on pyrolysis of materials have also been investigated.

  7. Density of Plutonium Turnings Generated from Machining Activities

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, John Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Vigil, Duane M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jachimowski, Thomas A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Archuleta, Alonso [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Arellano, Gerald Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Melton, Vince Lee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-10-20

    The purpose of this project was to determine the density of plutonium (Pu) turnings generated from the range of machining activities, using both surrogate material and machined Pu turnings. Verify that 500 grams (g) of plutonium will fit in a one quart container using a surrogate equivalent volume and that 100 grams of Pu will fit in a one quart Savy container.

  8. State of the Art in Photon-Density Estimation

    DEFF Research Database (Denmark)

    Hachisuka, Toshiya; Jarosz, Wojciech; Georgiev, Iliyan

    2013-01-01

    Photon-density estimation techniques are a popular choice for simulating light transport in scenes with complicated geometry and materials. This class of algorithms can be used to accurately simulate inter-reflections, caustics, color bleeding, scattering in participating media, and subsurface sc...

  9. State of the Art in Photon Density Estimation

    DEFF Research Database (Denmark)

    Hachisuka, Toshiya; Jarosz, Wojciech; Bouchard, Guillaume

    2012-01-01

    Photon-density estimation techniques are a popular choice for simulating light transport in scenes with complicated geometry and materials. This class of algorithms can be used to accurately simulate inter-reflections, caustics, color bleeding, scattering in participating media, and subsurface sc...

  10. Mass of materials: the impact of designers on construction ergonomics.

    Science.gov (United States)

    Smallwood, John

    2012-01-01

    Many construction injuries are musculoskeletal related in the form of sprains and strains arising from the handling of materials, which are specified by designers. The paper presents the results of a study conducted among delegates attending two 'designing for H&S' (DfH&S) seminars using a questionnaire. The salient findings include: the level of knowledge relative to the mass and density of materials is limited; designers generally do not consider the mass and density of materials when designing structures and elements and specifying materials; to a degree designers appreciate that the mass and density of materials impact on construction ergonomics; designers rate their knowledge of the mass and density of materials as limited, and designers appreciate the potential of the consideration of the mass and density of materials to contribute to an improvement in construction ergonomics. Conclusions include: designers lack the requisite knowledge relative to the mass and density of materials; designers are thus precluded from conducting optimum design hazard identification and risk assessments, and tertiary built environment designer education does not enlighten designers relative to construction ergonomics. Recommendations include: tertiary built environment designer education should construction ergonomics; professional associations should raise the level of awareness relative to construction ergonomics, and design practices should include a category 'mass and density of materials' in their practice libraries.

  11. Anti-Ferroelectric Ceramics for High Energy Density Capacitors

    Directory of Open Access Journals (Sweden)

    Aditya Chauhan

    2015-11-01

    Full Text Available With an ever increasing dependence on electrical energy for powering modern equipment and electronics, research is focused on the development of efficient methods for the generation, storage and distribution of electrical power. In this regard, the development of suitable dielectric based solid-state capacitors will play a key role in revolutionizing modern day electronic and electrical devices. Among the popular dielectric materials, anti-ferroelectrics (AFE display evidence of being a strong contender for future ceramic capacitors. AFE materials possess low dielectric loss, low coercive field, low remnant polarization, high energy density, high material efficiency, and fast discharge rates; all of these characteristics makes AFE materials a lucrative research direction. However, despite the evident advantages, there have only been limited attempts to develop this area. This article attempts to provide a focus to this area by presenting a timely review on the topic, on the relevant scientific advancements that have been made with respect to utilization and development of anti-ferroelectric materials for electric energy storage applications. The article begins with a general introduction discussing the need for high energy density capacitors, the present solutions being used to address this problem, and a brief discussion of various advantages of anti-ferroelectric materials for high energy storage applications. This is followed by a general description of anti-ferroelectricity and important anti-ferroelectric materials. The remainder of the paper is divided into two subsections, the first of which presents various physical routes for enhancing the energy storage density while the latter section describes chemical routes for enhanced storage density. This is followed by conclusions and future prospects and challenges which need to be addressed in this particular field.

  12. The Influence of Flame Retardant Treated Timber Density on Combustibility

    Directory of Open Access Journals (Sweden)

    Zbignev Karpovič

    2011-04-01

    Full Text Available Timber is widely used as a construction material in the majority of countries. In most cases, timber is the main structural material. Timber and timber fabrics used in building structure elements have to fulfill the requirements of fire safety. This article presents factors affecting the combustibility of timber, mainly the influence of flame retardants on the combustion phase, timber density and moisture. The influence of flame retardant treated timber density on combustibility is analyzed in this paper. Research was performed according to the requirements of the standard LST ISO 5657:1999 “Reaction to fire tests – ignitibility of building products using a radiant heat source”. The influence of flame retardant treated timber density on combustibility is assessed according to duration up to the combustion of the specimen. Article in Lithuanian

  13. Clathrates and beyond: Low-density allotropy in crystalline silicon

    Science.gov (United States)

    Beekman, Matt; Wei, Kaya; Nolas, George S.

    2016-12-01

    In its common, thermodynamically stable state, silicon adopts the same crystal structure as diamond. Although only a few alternative allotropic structures have been discovered and studied over the past six decades, advanced methods for structure prediction have recently suggested a remarkably rich low-density phase space that has only begun to be explored. The electronic properties of these low-density allotropes of silicon, predicted by first-principles calculations, indicate that these materials could offer a pathway to improving performance and reducing cost in a variety of electronic and energy-related applications. In this focus review, we provide an introduction and overview of recent theoretical and experimental results related to low-density allotropes of silicon, highlighting the significant potential these materials may have for technological applications, provided substantial challenges to their experimental preparation can be overcome.

  14. Photovoltaic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Duty, C.; Angelini, J.; Armstrong, B.; Bennett, C.; Evans, B.; Jellison, G. E.; Joshi, P.; List, F.; Paranthaman, P.; Parish, C.; Wereszczak, A.

    2012-10-15

    The goal of the current project was to help make the US solar industry a world leader in the manufacture of thin film photovoltaics. The overall approach was to leverage ORNL’s unique characterization and processing technologies to gain a better understanding of the fundamental challenges for solar cell processing and apply that knowledge to targeted projects with industry members. ORNL has the capabilities in place and the expertise required to understand how basic material properties including defects, impurities, and grain boundaries affect the solar cell performance. ORNL also has unique processing capabilities to optimize the manufacturing process for fabrication of high efficiency and low cost solar cells. ORNL recently established the Center for Advanced Thin-film Systems (CATS), which contains a suite of optical and electrical characterization equipment specifically focused on solar cell research. Under this project, ORNL made these facilities available to industrial partners who were interested in pursuing collaborative research toward the improvement of their product or manufacturing process. Four specific projects were pursued with industrial partners: Global Solar Energy is a solar industry leader in full scale production manufacturing highly-efficient Copper Indium Gallium diSelenide (CIGS) thin film solar material, cells and products. ORNL worked with GSE to develop a scalable, non-vacuum, solution technique to deposit amorphous or nanocrystalline conducting barrier layers on untextured stainless steel substrates for fabricating high efficiency flexible CIGS PV. Ferro Corporation’s Electronic, Color and Glass Materials (“ECGM”) business unit is currently the world’s largest supplier of metallic contact materials in the crystalline solar cell marketplace. Ferro’s ECGM business unit has been the world's leading supplier of thick film metal pastes to the crystalline silicon PV industry for more than 30 years, and has had operational

  15. Disordered hyperuniform heterogeneous materials

    Science.gov (United States)

    Torquato, Salvatore

    2016-10-01

    Disordered hyperuniform many-body systems are distinguishable states of matter that lie between a crystal and liquid: they are like perfect crystals in the way they suppress large-scale density fluctuations and yet are like liquids or glasses in that they are statistically isotropic with no Bragg peaks. These systems play a vital role in a number of fundamental and applied problems: glass formation, jamming, rigidity, photonic and electronic band structure, localization of waves and excitations, self-organization, fluid dynamics, quantum systems, and pure mathematics. Much of what we know theoretically about disordered hyperuniform states of matter involves many-particle systems. In this paper, we derive new rigorous criteria that disordered hyperuniform two-phase heterogeneous materials must obey and explore their consequences. Two-phase heterogeneous media are ubiquitous; examples include composites and porous media, biological media, foams, polymer blends, granular media, cellular solids, and colloids. We begin by obtaining some results that apply to hyperuniform two-phase media in which one phase is a sphere packing in d-dimensional Euclidean space {{{R}}d} . Among other results, we rigorously establish the requirements for packings of spheres of different sizes to be ‘multihyperuniform’. We then consider hyperuniformity for general two-phase media in {{{R}}d} . Here we apply realizability conditions for an autocovariance function and its associated spectral density of a two-phase medium, and then incorporate hyperuniformity as a constraint in order to derive new conditions. We show that some functional forms can immediately be eliminated from consideration and identify other forms that are allowable. Specific examples and counterexamples are described. Contact is made with well-known microstructural models (e.g. overlapping spheres and checkerboards) as well as irregular phase-separation and Turing-type patterns. We also ascertain a family of

  16. Role of baseline nodule density and changes in density and nodule features in the discrimination between benign and malignant solid indeterminate pulmonary nodules

    NARCIS (Netherlands)

    Xu, D.M.; van Klaveren, R.J.; de Bock, G.H.; Leusveld, A.L.M.; Dorrius, M.D.; Zhao, Y.; Wang, Y.; de Koning, H.J.; Scholten, E.T.; Verschakelen, J.; Prokop, M.; Oudkerk, M.

    2009-01-01

    Purpose: To retrospectively evaluate whether baseline nodule density or changes in density or nodule features could be used to discriminate between benign and malignant solid indeterminate nodules. Materials and methods: Solid indeterminate nodules between 50 and 500 mm(3) (4.6-9.8 mm) were assessed

  17. MateriApps — a Portal Site of Materials Science Simulation

    Science.gov (United States)

    Konishi, Yusuke; Igarashi, Ryo; Kasamatsu, Shusuke; Kato, Takeo; Kawashima, Naoki; Kawatsu, Tsutomu; Kouta, Hikaru; Noda, Masashi; Sasaki, Shoichi; Terada, Yayoi; Todo, Synge; Tsuchida, Shigehiro; Yoshimi, Kazuyoshi; Yoshizawa, Kanako

    "MateriApps" is a portal website of computational materials science simulation that has a database containing over 100 application software including density functional theory calculation, quantum chemistry, molecular dynamics, etc. On the MateriApps website, researchers can find applications suitable for their own research in materials science by browsing the website or searching by keywords. We also provide forums and tutorial courses of applications. In order to avoid troublesome installation procedures and provide users an environment in which they can try out various applications easily, we develop and freely distribute "MateriApps LIVE!," a live Linux system, in which several applications introduced in MateriApps are pre-installed.

  18. Importing low-density ideas to high-density revitalisation

    DEFF Research Database (Denmark)

    Anrholtz, Jens; Ibsen, Christian Lyhne; Ibsen, Flemming

    2016-01-01

    Why did union officials from a high-union-density country like Denmark choose to import an organising strategy from low-density countries such as the US and the UK? Drawing on in-depth interviews with key union officials and internal documents, the authors of this article argue two key points. Fi...... cherry-pick some elements while leaving fundamental aspects out. The study nevertheless indicates that a lack of coherency and model-fit to Danish industrial relations might hamper the positive effects of the organising strategy....

  19. Superfluid density in the d-density-wave scenario.

    Science.gov (United States)

    Wang, Q H; Han, J H; Lee, D H

    2001-08-13

    Recently Chakravarty, Laughlin, Morr, and Nayak [Phys. Rev. B 62, 4880 (2000)] made an interesting proposal that the cuprate superconductors possess a hidden " d-density-wave" (DDW) order. We study the implication of this proposal for the superfluid density rho(s). We find that it predicts a temperature gradient [d rho(s)/dT](T = 0) that is strongly doping dependent near the critical doping at which the superconducting gap vanishes. This demonstrates that the DDW scenario is inconsistent with existing well-established experimental data.

  20. Comparison of density estimators. [Estimation of probability density functions

    Energy Technology Data Exchange (ETDEWEB)

    Kao, S.; Monahan, J.F.

    1977-09-01

    Recent work in the field of probability density estimation has included the introduction of some new methods, such as the polynomial and spline methods and the nearest neighbor method, and the study of asymptotic properties in depth. This earlier work is summarized here. In addition, the computational complexity of the various algorithms is analyzed, as are some simulations. The object is to compare the performance of the various methods in small samples and their sensitivity to change in their parameters, and to attempt to discover at what point a sample is so small that density estimation can no longer be worthwhile. (RWR)

  1. Materializing ideas

    DEFF Research Database (Denmark)

    Strandvad, Sara Malou

    2011-01-01

    to investigate how the evolving object may form an active part in the collaborative process of its making. The article identifies three moments when the evolving object becomes decisive for the collaboration: the idea has to be detached to enable collaboration; attachments between collaborators are made via...... the evolving object; and closure of the product is postponed to enhance creative development. Thus, the article suggests that cultural objects and the processes of their making are co-produced, evolve simultaneously and are mutually constitutive. In this way, the object may have effects even while......Based on a qualitative study of development processes in the Danish film industry, this article sketches a socio-material perspective for analysing the production of culture. Whereas previous studies of cultural production have identified social factors in cultural production, this article sets out...

  2. Virtual materiality

    DEFF Research Database (Denmark)

    Søndergaard, Dorte Marie

    to bullying practices in school. The theoretical question concerns the conceptual challenges that arise from empirical data which contain 1. children’s narratives about matter and meaning as they intertwine in their nightly dreams, 2. the observations of children’s’ computer gaming practices as well...... the character and effects of the skeleton army, which came across the sea to drown the boys in Phillip’s school class: a central scene in one of the dreams he recounted? Are the boat and the water in that dream materialities? Discourse? Part of some kind of enacted subjectivity? How will our decision of which......, experiences etc. Among these many interacting forces technologies play a crucial part – as do bodies, whether they are fighting, playing, dreaming, loving or hating bodies. And as do weapons - whether in the shape of virtual weapons of the computer games (as in e.g. Battlefield, Counter Strike, Grand Theft...

  3. Materializing superghosts

    Science.gov (United States)

    Alexandrov, V.; Krotov, D.; Losev, A.; Lysov, V.

    2007-12-01

    The off-shell Batalin-Vilkovysky (BV) realization has been constructed for N = 1, d = 10 super-Yang-Mills theory with seven auxiliary fields. This becomes possible due to the materialized ghost phenomenon. Namely, supersymmetry ghosts are coordinates on a manifold B of ten-dimensional spinors with the pure spinors cut out. Auxiliary fields are sections of a bundle over B, and supersymmetry transformations are nonlinear in ghosts. By integrating out the auxiliary fields, we obtain an on-shell supersymmetric BV action with quadratic terms in the antifields. Exactly this on-shell BV action was obtained in our previous paper after integration out of auxiliary fields in the framework of a pure spinor superfield formalism.

  4. Materials for Alternative Energies: Computational Materials Discovery and Crystal Structure Prediction

    Science.gov (United States)

    Wolverton, Chris

    2013-03-01

    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.

  5. A novel muon detector for borehole density tomography

    Science.gov (United States)

    Bonneville, Alain; Kouzes, Richard T.; Yamaoka, Jared; Rowe, Charlotte; Guardincerri, Elena; Durham, J. Matthew; Morris, Christopher L.; Poulson, Daniel C.; Plaud-Ramos, Kenie; Morley, Deborah J.; Bacon, Jeffrey D.; Bynes, James; Cercillieux, Julien; Ketter, Chris; Le, Khanh; Mostafanezhad, Isar; Varner, Gary; Flygare, Joshua; Lintereur, Azaree T.

    2017-04-01

    Muons can be used to image the density of materials through which they pass, including geological structures. Subsurface applications of the technology include tracking fluid migration during injection or production, with increasing concern regarding such timely issues as induced seismicity or chemical leakage into aquifers. Current density monitoring options include gravimetric data collection and active or passive seismic surveys. One alternative, or complement, to these methods is the development of a muon detector that is sufficiently compact and robust for deployment in a borehole. Such a muon detector can enable imaging of density structure to monitor small changes in density - a proxy for fluid migration - at depths up to 1500 m. Such a detector has been developed, and Monte Carlo modeling methods applied to simulate the anticipated detector response. Testing and measurements using a prototype detector in the laboratory and shallow underground laboratory demonstrated robust response. A satisfactory comparison with a large drift tube-based muon detector is also presented.

  6. Numerical analysis of wet separation of particles by density differences

    CERN Document Server

    Markauskas, Darius

    2016-01-01

    Wet particle separation is widely used in mineral processing and plastic recycling to separate mixtures of particulate materials into further usable fractions due to density differences. This work presents efforts aiming to numerically analyze the wet separation of particles with different densities. In the current study the discrete element method (DEM) is used for the solid phase while the smoothed particle hydrodynamics (SPH) is used for modeling of the liquid phase. The two phases are coupled by the use of a volume averaging technique. In the current study, simulations of spherical particle separation were performed. In these simulations, a set of generated particles with two different densities is dropped into a rectangular container filled with liquid. The results of simulations with two different mixtures of particles demonstrated how separation depends on the densities of particles.

  7. Determining the Limiting Current Density of Vanadium Redox Flow Batteries

    Directory of Open Access Journals (Sweden)

    Jen-Yu Chen

    2014-09-01

    Full Text Available All-vanadium redox flow batteries (VRFBs are used as energy storage systems for intermittent renewable power sources. The performance of VRFBs depends on materials of key components and operating conditions, such as current density, electrolyte flow rate and electrolyte composition. Mass transfer overpotential is affected by the electrolyte flow rate and electrolyte composition, which is related to the limiting current density. In order to investigate the effect of operating conditions on mass transport overpotential, this study established a relationship between the limiting current density and operating conditions. First, electrolyte solutions with different states of charge were prepared and used for a single cell to obtain discharging polarization curves under various operating conditions. The experimental results were then analyzed and are discussed in this paper. Finally, this paper proposes a limiting current density as a function of operating conditions. The result helps predict the effect of operating condition on the cell performance in a mathematical model.

  8. Photovoltaic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Duty, C.; Angelini, J.; Armstrong, B.; Bennett, C.; Evans, B.; Jellison, G. E.; Joshi, P.; List, F.; Paranthaman, P.; Parish, C.; Wereszczak, A.

    2012-10-15

    The goal of the current project was to help make the US solar industry a world leader in the manufacture of thin film photovoltaics. The overall approach was to leverage ORNL’s unique characterization and processing technologies to gain a better understanding of the fundamental challenges for solar cell processing and apply that knowledge to targeted projects with industry members. ORNL has the capabilities in place and the expertise required to understand how basic material properties including defects, impurities, and grain boundaries affect the solar cell performance. ORNL also has unique processing capabilities to optimize the manufacturing process for fabrication of high efficiency and low cost solar cells. ORNL recently established the Center for Advanced Thin-film Systems (CATS), which contains a suite of optical and electrical characterization equipment specifically focused on solar cell research. Under this project, ORNL made these facilities available to industrial partners who were interested in pursuing collaborative research toward the improvement of their product or manufacturing process. Four specific projects were pursued with industrial partners: Global Solar Energy is a solar industry leader in full scale production manufacturing highly-efficient Copper Indium Gallium diSelenide (CIGS) thin film solar material, cells and products. ORNL worked with GSE to develop a scalable, non-vacuum, solution technique to deposit amorphous or nanocrystalline conducting barrier layers on untextured stainless steel substrates for fabricating high efficiency flexible CIGS PV. Ferro Corporation’s Electronic, Color and Glass Materials (“ECGM”) business unit is currently the world’s largest supplier of metallic contact materials in the crystalline solar cell marketplace. Ferro’s ECGM business unit has been the world's leading supplier of thick film metal pastes to the crystalline silicon PV industry for more than 30 years, and has had operational

  9. Does gravity help to improve seismic inversion for density?

    Science.gov (United States)

    Blom, Nienke; Böhm, Christian; Fichtner, Andreas

    2016-04-01

    Density is one of the most important material properties that influence the dynamics of our planet's interior, and knowledge of it alongside with knowledge of seismic velocities will help constrain composition more directly. However, the variation of density inside the Earth is poorly known. The travel times of seismic waves, the classical tool to probe the Earth's interior, are barely sensitive to density (with large tradeoffs) and gravity is so extremely non-unique that very little information can be extracted from it without placing very strong prior constraints. As a result, density has, up until now, usually only been regarded as a derived quantity, which may lead to erroneous interpretations. Here, we aim to determine to what extent it is possible to image density as an independent parameter using modern geophysical techniques. The main technique is seismic (full) waveform inversion, which is more sensitive to density than travel-times alone, for the simple reason that more information of the seismogram is being used: basically the amplitude and phase of every wiggle. We construct synthetic tests in 2-D where density is a completely independent parameter from S-wave velocity and P-wave velocity - this setup (albeit physically unrealistic) has the advantage that our ability to image density independently is assessed in an unbiased way. We find that it is indeed possible to image density using waveform inversion. If prior information, such as constraints on S- and P-velocity structure, is included in the inversion, the results for density are markedly improved. The use of gravity data as an additional observable, however, deteriorates the inversion results. This is because of the significant non-uniqueness of potential field measurements, so that an unconstrained update based on gravity will only almost definitely work to push the inversion in the wrong direction.

  10. Engineered monodisperse mesoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Saunders, R.S.; Small, J.H.; Lagasse, R.R.; Schroeder, J.L.; Jamison, G.M.

    1997-08-01

    Porous materials technology has developed products with a wide variety of pore sizes ranging from 1 angstrom to 100`s of microns and beyond. Beyond 15{angstrom} it becomes difficult to obtain well ordered, monodisperse pores. In this report the authors describe efforts in making novel porous material having monodisperse, controllable pore sizes spanning the mesoporous range (20--500 {angstrom}). They set forth to achieve this by using unique properties associated with block copolymers--two linear homopolymers attached at their ends. Block copolymers phase separate into monodisperse mesophases. They desired to selectively remove one of the phases and leave the other behind, giving the uniform monodisperse pores. To try to achieve this the authors used ring-opening metathesis polymerization to make the block copolymers. They synthesized a wide variety of monomers and surveyed their polymers by TGA, with the idea that one phase could be made thermally labile while the other phase would be thermally stable. In the precipitated and sol-gel processed materials, they determined by porosimetry measurements that micropores, mesopores, and macropores were created. In the film processed sample there was not much porosity present. They moved to a new system that required much lower thermal treatments to thermally remove over 90% of the labile phase. Film casting followed by thermal treatment and solvent extraction produced the desired monodisperse materials (based solely on SEM results). Modeling using Density Functional Theory was also incorporated into this project. The modeling was able to predict accurately the domain size and spacing vs. molecular weight for a model system, as well as accurate interfacial thicknesses.

  11. Ferroelectrically driven spatial carrier density modulation in graphene.

    Science.gov (United States)

    Baeumer, Christoph; Saldana-Greco, Diomedes; Martirez, John Mark P; Rappe, Andrew M; Shim, Moonsub; Martin, Lane W

    2015-01-22

    The next technological leap forward will be enabled by new materials and inventive means of manipulating them. Among the array of candidate materials, graphene has garnered much attention; however, due to the absence of a semiconducting gap, the realization of graphene-based devices often requires complex processing and design. Spatially controlled local potentials, for example, achieved through lithographically defined split-gate configurations, present a possible route to take advantage of this exciting two-dimensional material. Here we demonstrate carrier density modulation in graphene through coupling to an adjacent ferroelectric polarization to create spatially defined potential steps at 180°-domain walls rather than fabrication of local gate electrodes. Periodic arrays of p-i junctions are demonstrated in air (gate tunable to p-n junctions) and density functional theory reveals that the origin of the potential steps is a complex interplay between polarization, chemistry, and defect structures in the graphene/ferroelectric couple.

  12. The effect of aggregate density on pavement performance of SMA-13 asphalt mixture

    Directory of Open Access Journals (Sweden)

    Qiao Yinping

    2016-05-01

    Full Text Available This paper chooses the top layer SMA-13 asphalt mixture material as the research object. Basalt was selected as pavement material, and modified SBS asphalt was used as a cementing material. Two basalt aggregates with different densities were used to carry out standard Marshall test in the laboratory.Aimed at the volume parameters of the asphalt mixture carry on anaiysis,and obtian the effect of aggregate density on pavement performance of SMA-13 asphalt mixture, which is that the density of aggregate has a significant effect on the void ratio, saturation, and the gap rate of the aggregate, thus affecting the pavement performance of the asphalt mixture

  13. Six Decades of Spiral Density Wave Theory

    Science.gov (United States)

    Shu, Frank H.

    2016-09-01

    The theory of spiral density waves had its origin approximately six decades ago in an attempt to reconcile the winding dilemma of material spiral arms in flattened disk galaxies. We begin with the earliest calculations of linear and nonlinear spiral density waves in disk galaxies, in which the hypothesis of quasi-stationary spiral structure (QSSS) plays a central role. The earliest success was the prediction of the nonlinear compression of the interstellar medium and its embedded magnetic field; the earliest failure, seemingly, was not detecting color gradients associated with the migration of OB stars whose formation is triggered downstream from the spiral shock front. We give the reasons for this apparent failure with an update on the current status of the problem of OB star formation, including its relationship to the feathering substructure of galactic spiral arms. Infrared images can show two-armed, grand design spirals, even when the optical and UV images show flocculent structures. We suggest how the nonlinear response of the interstellar gas, coupled with overlapping subharmonic resonances, might introduce chaotic behavior in the dynamics of the interstellar medium and Population I objects, even though the underlying forces to which they are subject are regular. We then move to a discussion of resonantly forced spiral density waves in a planetary ring and their relationship to the ideas of disk truncation, and the shepherding of narrow rings by satellites orbiting nearby. The back reaction of the rings on the satellites led to the prediction of planet migration in protoplanetary disks, which has had widespread application in the exploding data sets concerning hot Jupiters and extrasolar planetary systems. We then return to the issue of global normal modes in the stellar disk of spiral galaxies and its relationship to the QSSS hypothesis, where the central theoretical concepts involve waves with negative and positive surface densities of energy and angular

  14. Density matrix quantum Monte Carlo

    CERN Document Server

    Blunt, N S; Spencer, J S; Foulkes, W M C

    2013-01-01

    This paper describes a quantum Monte Carlo method capable of sampling the full density matrix of a many-particle system, thus granting access to arbitrary reduced density matrices and allowing expectation values of complicated non-local operators to be evaluated easily. The direct sampling of the density matrix also raises the possibility of calculating previously inaccessible entanglement measures. The algorithm closely resembles the recently introduced full configuration interaction quantum Monte Carlo method, but works all the way from infinite to zero temperature. We explain the theory underlying the method, describe the algorithm, and introduce an importance-sampling procedure to improve the stochastic efficiency. To demonstrate the potential of our approach, the energy and staggered magnetization of the isotropic antiferromagnetic Heisenberg model on small lattices and the concurrence of one-dimensional spin rings are compared to exact or well-established results. Finally, the nature of the sign problem...

  15. Union Density and Hospital Outcomes.

    Science.gov (United States)

    Koys, Daniel J; Martin, Wm Marty; LaVan, Helen; Katz, Marsha

    2015-01-01

    The authors address the hospital outcomes of patient satisfaction, healthcare quality, and net income per bed. They define union density as the percentage of a hospital's employees who are in unions, healthcare quality as its 30-day acute myocardial infraction (AMI; heart attack) mortality rate, and patient satisfaction as its overall Hospital Consumer Assessment of Healthcare Providers and Systems score. Using a random sample of 84 union and 84 nonunion hospitals from across the United States, multiple regression analyses show that union density is negatively related to patient satisfaction. Union density is not related to healthcare quality as measured by the AMI mortality rate or to net income per bed. This implies that unions per se are not good or bad for hospitals. The authors suggest that it is better for hospital administrators to take a Balanced Scorecard approach and be concerned about employee satisfaction, patient satisfaction, healthcare quality, and net income.

  16. High Energy Density Laboratory Astrophysics

    CERN Document Server

    Lebedev, Sergey V

    2007-01-01

    During the past decade, research teams around the world have developed astrophysics-relevant research utilizing high energy-density facilities such as intense lasers and z-pinches. Every two years, at the International conference on High Energy Density Laboratory Astrophysics, scientists interested in this emerging field discuss the progress in topics covering: - Stellar evolution, stellar envelopes, opacities, radiation transport - Planetary Interiors, high-pressure EOS, dense plasma atomic physics - Supernovae, gamma-ray bursts, exploding systems, strong shocks, turbulent mixing - Supernova remnants, shock processing, radiative shocks - Astrophysical jets, high-Mach-number flows, magnetized radiative jets, magnetic reconnection - Compact object accretion disks, x-ray photoionized plasmas - Ultrastrong fields, particle acceleration, collisionless shocks. These proceedings cover many of the invited and contributed papers presented at the 6th International Conference on High Energy Density Laboratory Astrophys...

  17. A Tryst With Density: Walter Kohn and Density Functional Theory

    Indian Academy of Sciences (India)

    Shobhana Narasimhan

    2017-08-01

    Walter Kohn transformed theoretical chemistry and solid statephysics with his development of density functional theory, forwhich he was awarded the Nobel Prize. This article tries toexplain, in simple terms, why this was an important advancein the field, and to describe precisely what it was that he (togetherwith his collaborators Pierre Hohenberg and Lu JeuSham) achieved.

  18. Sheared solid materials

    Indian Academy of Sciences (India)

    Akira Onuki; Akira Furukawa; Akihiko Minami

    2005-05-01

    We present a time-dependent Ginzburg–Landau model of nonlinear elasticity in solid materials. We assume that the elastic energy density is a periodic function of the shear and tetragonal strains owing to the underlying lattice structure. With this new ingredient, solving the equations yields formation of dislocation dipoles or slips. In plastic flow high-density dislocations emerge at large strains to accumulate and grow into shear bands where the strains are localized. In addition to the elastic displacement, we also introduce the local free volume . For very small the defect structures are metastable and long-lived where the dislocations are pinned by the Peierls potential barrier. However, if the shear modulus decreases with increasing , accumulation of around dislocation cores eventually breaks the Peierls potential leading to slow relaxations in the stress and the free energy (aging). As another application of our scheme, we also study dislocation formation in two-phase alloys (coherency loss) under shear strains, where dislocations glide preferentially in the softer regions and are trapped at the interfaces.

  19. Forecasting Thermosphere Density: an Overview

    Science.gov (United States)

    Bruinsma, S.

    2015-12-01

    Our knowledge of the thermosphere has improved considerably since 2000 thanks to the availability of high-resolution accelerometer inferred densities. Consequently, precision and shortcomings of thermosphere models are better known. Thermosphere density forecast accuracy is limited by: 1) the accuracy of the thermosphere model 2) the solar and geomagnetic activity forecast 3) the quality of the data assimilation system. The precision of semi-empirical thermosphere models is 10-25%. Solar activity forecasts can be accurate up to 5 days. They become less accurate with time, but some proxies are more forecastable than others. Geomagnetic activity forecasting is more problematic, since in most cases storm events cannot be predicted on any time scale. The forecast accuracy is ultimately bounded by the thermosphere model precision and the (varying) degree to which mainly the solar proxy represents EUV heating of the atmosphere. Both errors can be corrected for by means of near real time (nrt) assimilation of satellite drag data, provided that the data is of high quality. At present, only the classified High Accuracy Satellite Drag Model of the Air Force has that capability operationally, even if other prototype nrt models have been developed. Data assimilation significantly improves density forecasts up to 72-hours out; there is no gain for longer periods due to the short memory of the thermosphere system. Only physical models, e.g. TIMEGCM and CTIPe, can in principle reproduce the dynamic changes in density for example during geomagnetic storms. However, accurate information on atmospheric heating is often missing, or not used. When it is, observed and modeled Traveling Atmospheric Disturbances are very similar. Nonmigrating tides and waves propagating from the lower atmosphere cause longitudinal density variations; sources of geophysical noise for semi-empirical models, they can be predicted qualitatively and sometimes quantitatively with physical models. This

  20. Critical density of urban traffic

    CERN Document Server

    da Silva, Adilton Jose

    2010-01-01

    A modified version of the Intelligent Driver Model was used to simulate traffic in the district of Afogados, in the city of Recife, Brazil, with the objective to verify whether the complexity of the underlying street grid, with multiple lane streets, crossings, and semaphores, is capable of exhibiting the effect of critical density: appearance of a maximum in the vehicle flux versus density curve. Numerical simulations demonstrate that this effect indeed is observed on individual avenues, while the phase offset among the avenues results in damping of this effect for the region as a whole.