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Sample records for short-range order parameters

  1. Determination of thermodynamical coefficients for Mo-W alloys according to short-range order parameters

    International Nuclear Information System (INIS)

    Erokhin, L.N.; Mokrov, A.P.; Shivrin, O.N.; Khanina, N.I.

    1986-01-01

    A method is proposed for determining thermodynamical coefficients according to short-range order parameters. The method approbation for Mo-W alloys has shown a good agreement between the thermodynamical and diffusion data. The Mo-W system in the concentration range under study is close to the ideal one. The calculated relative error of determination of interdiffusion coefficients in alloys of the Mo-W system does not exceed 16%

  2. Magnetic short range order in Gd

    International Nuclear Information System (INIS)

    Child, H.R.

    1976-01-01

    Quasielastic neutron scattering has been used to investigate magnetic short range order in Gd for 80 0 K 0 K. Short range order exists throughout this range from well below T/sub C/ = 291 0 K to well above it and can be reasonably well described by an anisotropic Orstein-Zernike form for chi

  3. Short range order in liquid pnictides

    International Nuclear Information System (INIS)

    Mayo, M; Makov, G; Yahel, E; Greenberg, Y

    2013-01-01

    Liquid pnictides have anomalous physical properties and complex radial distribution functions. The quasi-crystalline model of liquid structure is applied to interpret the three-dimensional structure of liquid pnictides. It is shown that all the column V elements can be characterized by a short range order lattice symmetry similar to that of the underlying solid, the A7 structure, which originates from a Peierls distorted simple cubic lattice. The evolution of the liquid structure down the column as well as its temperature and pressure dependence is interpreted by means of the effect of thermodynamic parameters on the Peierls distortion. Surprisingly, it is found that the Peierls effect increases with temperature and the nearest neighbour distances exhibit negative thermal expansion. (paper)

  4. Magnetic short range order and the exchange coupling in magnets

    International Nuclear Information System (INIS)

    Antropov, V.P.

    2006-01-01

    We discuss our recent results of time-dependent density functional simulations of magnetic properties of Fe and Ni at finite temperatures. These results indicated that a strong magnetic short range order is responsible for the magnetic properties of elementary Ni and any itinerant magnet in general. We demonstrated that one can use the value of the magnetic short range order parameter to produce new quantitative classification of magnets. We also discuss the nature of the exchange coupling and its connection with the short range order. The spin-wave like propagating and diffusive excitations in paramagnetic localized systems with small short range order have been predicted while in the itinerant systems the short range order is more complicated. The possible smallness of the quantum factor in the itinerant magnets with short range order is discussed

  5. Magnetic short-range order in Gd

    International Nuclear Information System (INIS)

    Child, H.R.

    1978-01-01

    The magnetic short-range order in a ferromagnetic, isotopically enriched 160 Gd metal single crystal has been investigated by quasielastic scattering of 81-meV neutrons. Since Gd behaves as an S-state ion in the metal, little anisotropy is expected in its magnetic behavior. However, the data show that there is anisotropic short-range order present over a large temperature interval both above and below T/sub C/. The data have been analyzed in terms of an Ornstein-Zernike Lorentzian form with anisotropic correlation ranges. These correlation ranges as deduced from the observed data behave normally above T/sub C/ but seem to remain constant over a fairly large interval below T/sub C/ before becoming unobservable at lower temperatures. These observations suggest that the magnetic ordering in Gd may be a more complicated phenomenon than first believed

  6. Measurements of short-range ordering in Ni3Al

    International Nuclear Information System (INIS)

    Okamoto, J.K.; Ahn, C.C.

    1992-01-01

    This paper reports on extended electron energy-loss fine structure (EXELFS) that has been used to measure short-range ordering in Ni 3 Al. Films of fcc Ni 3 Al with suppressed short-range order synthesized by vacuum evaporation of Ni 3 Al onto room temperature substrates. EXELFS data were taken from both Al K and Ni L 23 edges. The development of short-range order was observed after the samples were annealed for various times at temperatures below 350 degrees C. Upon comparison with ab initio planewave EXELFS calculations, it was found that the Warren-Cowley short-range order parameter a(1nn) changed by about -0.1 after 210 minutes of annealing at 150 degrees C

  7. Short range order of selenite glasses

    Czech Academy of Sciences Publication Activity Database

    Neov, S.; Gerasimova, I.; Yordanov, S.; Lakov, L.; Mikula, Pavol; Lukáš, Petr

    1999-01-01

    Roč. 40, č. 2 (1999), s. 111-112 ISSN 0031-9090 R&D Projects: GA AV ČR KSK1010104 Keywords : short range * selenite glasses Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.822, year: 1999

  8. Short-range order parameters in amorphous YBaS4X7(X-S, SE, TE) films

    International Nuclear Information System (INIS)

    Hajiyev, E.S.

    2005-01-01

    Full text : Electron scattering intensity curves from amorphous YbAs 4 X 7 (X-S, SE, TE) films have ben obtained by the transmission electron diffraction (TED) method with rotation sector before screen up. The energy of electrons was 100 keV. Amorphous samples were crystallized and the composition of the products were measured by TED. The atomic radial distribution function has been calculated by the Fourier synthesis of intensities in the TED of amorphous YbAs 4 X 7 (X-S, SE, TE) films. The interatomic average distances of As - S (Se, Te) and As-Yb + 2 and partial coordination numbers have been estimated in these thilms. Based on these numbers, chemical orders in these films differ. This difference is due to differing topological order in the amorphous YbAs 4 X 7 (X-S, SE, TE) films

  9. Chemical and topological short-range order in metallic glasses

    International Nuclear Information System (INIS)

    Vincze, I.; Schaafsma, A.S.; Van der Woude, F.; Kemeny, T.; Lovas, A.

    1980-10-01

    Moessbauer spectroscopy is applied to the study of chemical short-range order in (Fe,Ni)B metallic glasses. It is found that the atomic arrangement in melt-quenched glasses closely resembles that of the crystalline counterparts (Fe 3 B is tetragonal, Ni 3 B is orthorombic). The distribution of transition metal atoms is not random at high Ni concentrations: Ni atoms prefer a neighbourhood with a higher boron coordination. (P.L.)

  10. Temperature dependence of the short-range order parameter and the concentration dependence of the order disorder temperature for Ni-Pt and Ni-Fe systems in the improved statistical pseudopotential approximation

    International Nuclear Information System (INIS)

    Khwaja, F.A.

    1980-08-01

    The calculations for the temperature dependence of the first shell short-range order (SRO) parameter for Ni 3 Fe using the cubic approximation of Tahir Kheli, and the concentration dependence of order-disorder temperature Tsub(c) for Ni-Fe and Ni-Pt systems using the linear approximation, have been carried out in the framework of pseudopotential theory. It is shown that the cubic approximation yields a good agreement between the theoretical prediction of the α 1 and the experimental data. Results for the concentration dependence of the Tsub(c) show that improvements in the statistical pseudo-potential approach are essential to achieve a good agreement with experiment. (author)

  11. Amorphous photonic crystals with only short-range order.

    Science.gov (United States)

    Shi, Lei; Zhang, Yafeng; Dong, Biqin; Zhan, Tianrong; Liu, Xiaohan; Zi, Jian

    2013-10-04

    Distinct from conventional photonic crystals with both short- and long-range order, amorphous photonic crystals that possess only short-range order show interesting optical responses owing to their unique structural features. Amorphous photonic crystals exhibit unique light scattering and transport, which lead to a variety of interesting phenomena such as isotropic photonic bandgaps or pseudogaps, noniridescent structural colors, and light localization. Recent experimental and theoretical advances in the study of amorphous photonic crystals are summarized, focusing on their unique optical properties, artificial fabrication, bionspiration, and potential applications. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Short range order in FeCo-X alloys

    International Nuclear Information System (INIS)

    Fultz, B.

    1988-01-01

    Moessbauer spectrometry was used to study the kinetics of chemical ordering in FeCo and in FeCo alloyed with ternary solutes. With respect to the binary FeCo alloy, the kinetics of B2 ordering were slowed when 2% of 4d- or 5d-series ternary solute atoms were present, but 3p- and 3d-series ternary solutes had little effect on ordering kinetics. The relaxation of order around the ternary solute atoms could be discerned in Moessbauer spectra, and it seems that the development of B2 short range order is influenced by structural relaxations around the ternary solute atoms. Different thermal treatments were shown to cause different relaxations of and correlations, suggesting that Moessbauer spectrometry can be used to identify different kinetic paths of ordering in ternary alloys. (orig.)

  13. Influence of short range ordering and clustering on transport properties

    International Nuclear Information System (INIS)

    Vigier, G.; Pelletier, J.M.

    1982-01-01

    The influence of short range ordering and clustering phenomena on the electrical resistivity p and the thermopower S is investigated both theoretically and experimentally. According to the considered alloys either increases or decreases of transport properties may be observed when deviations from a random distribution of solute atoms occur. These observations are explained with a model based on free electrons and Born approximations the importance of the potential choice is underlined; two kinds of description of the structure factor are investigated. A good semiquantitative agreement is obtained between computed results and experimental observations

  14. Methods for studying short-range order in solid binary solutions

    International Nuclear Information System (INIS)

    Beranger, Gerard

    1969-12-01

    The short range order definition and its characteristic parameters are first recalled. The different methods to study the short range order are then examined: X ray diffusion, electrical resistivity, specific heat and thermoelectric power, neutron diffraction, electron spin resonance, study of thermodynamic and mechanical properties. The theory of the X ray diffraction effects due to short range order and the subsequent experimental method are emphasized. The principal results obtained from binary Systems, by the different experimental techniques, are reported and briefly discussed. The Au-Cu, Li-Mg, Au-Ni and Cu-Zn Systems are moreover described. (author) [fr

  15. Fluctuations in substitution type alloys and their analyses. Short-range order structures

    International Nuclear Information System (INIS)

    Iwasaki, Hiroshi; Ohshima, Ken-ichi

    2010-01-01

    This article is the fifth of the serial lecture, microstructures and fluctuations, in this magazine. The formula of X-ray diffuse scattering intensity was derived for binary alloys by introducing short-range order parameters. Diffuse scattering intensities for a single crystal Cu 3 Au were measured above critical temperature for ordering. The short-range parameters were obtained by a three-dimensional Fourier analysis. The long-range pair interaction between atoms was originated from the indirect screening interaction due to conduction electrons. A detailed study was made on short-range-order diffuse scattering from Cu 3 Au in the disordered state by electron diffraction. Fourfold splitting of the diffuse scattering was observed at 110 in the reciprocal lattice, and this result was attributed to the reflection of the form of the Fermi surface. The X-ray diffuse scattering intensity was measured at room temperature for disordered Cu-Pd alloys for the six composition of Pd. Twofold and fourfold splitting of diffuse scattering due to the short-range order (SRO) were observed at 100, 110 and equivalent positions respectively from alloys with more than 13.0at% Pd. The SRO parameters were determined from all the six alloys. For Cu-Pt alloys, the diffuse scattering originated from the correlation between Cu and Pt layers in direction was observed in addition to the one due to the reflection of the Fermi surface imaging. (author)

  16. Positional short-range order in the nematic phase of n BABAs

    Science.gov (United States)

    Usha Deniz, K.; Pepy, G.; Parette, G.; Keller, P.

    1991-10-01

    The positional short-range order, SRO ⊥, perpendicular to the nematic director n̂ has been studied in the fibre-type nematics, nBABAs, by neutron diffraction. SRO ⊥ is found to be dependent on other types of nematic short-range order but not on the orientational long-range order.

  17. Study of short range order in alloy of glassy metals and effect of neutron irradiation on them

    International Nuclear Information System (INIS)

    Habibi, S.; Banaee, N.; Salman, M.; Gupta, A.; Principi, G.

    2000-04-01

    In this paper, we have studied a series of glassy metals with composition Fe 78-x Ni x Si 8 B 14 with x=0, 15, 25,38,53, 58. We have used Moessbauer spectroscopy to get information about short range order and local structure in these alloys. The specimens are exposed to neutron irradiation to perturb local structure and their short range order. The hyperfine parameters obtained from spectra before and after n-irradiation and are compared

  18. Short range order of Mg-Cd-alloys during the transition from the solid to the molten state

    International Nuclear Information System (INIS)

    Boos, A.; Steeb, S.

    1977-01-01

    Recently a method was published for the determination of short range order parameters in binary melts and also a method for the determination of the concentration of different structures which form such a melt. These methods are used in the present work to evaluate the atomic structure of Mg-Cd-melts and to reval the changes in short range order during the melting process. (orig.) [de

  19. Magnetic susceptibility as a method of investigation of short-range order in strongly nonstoichiometric carbides

    International Nuclear Information System (INIS)

    Nazarova, S.Z.; Gusev, A.I.

    2001-01-01

    Magnetic susceptibility in disordered and ordered carbides of transition metals (M = Ti, Zr, Hf, Nb, Ta) was studied, the results are generalized. It was ascertained that the change in carbide susceptibility induced by deviation from stoichiometry stems from specific features of electronic spectra of the compounds. The use of magnetic susceptibility for determining structural disorder-order transitions is discussed. It is shown that change in the contribution made by orbital paramagnetism, resulting from short-range order formation, is the reason of decrease in susceptibility of nonstoichiometric carbides during the ordering. Experimentally obtained data on susceptibility permitted evaluating short- and far-range order parameters in NbC y , TaC y , TiC y and HfC y carbides [ru

  20. Magnetism and atomic short-range order in Ni-Rh alloys

    Science.gov (United States)

    Carnegie, D. W., Jr.; Claus, H.

    1984-07-01

    Low-field ac susceptibility measurements of Ni-Rh samples of various concentrations are presented. Giant effects of the metallurgical state on the magnetic ordering temperature are associated with changes in the degree of atomic short-range order. By careful control of this degree of short-range order, it is possible to demonstrate the existence of a spin-glass state in Ni-Rh alloys.

  1. Double scattering of light from Biophotonic Nanostructures with short-range order

    Energy Technology Data Exchange (ETDEWEB)

    Noh, Heeso; Liew, Seng Fatt; Saranathan, Vinodkumar; Prum, Richard O.; Mochrie, Simon G.J.; Dufresne, Eric R.; Cao, Hui (Yale)

    2010-07-28

    We investigate the physical mechanism for color production by isotropic nanostructures with short-range order in bird feather barbs. While the primary peak in optical scattering spectra results from constructive interference of singly-scattered light, many species exhibit secondary peaks with distinct characteristic. Our experimental and numerical studies show that these secondary peaks result from double scattering of light by the correlated structures. Without an analog in periodic or random structures, such a phenomenon is unique for short-range ordered structures, and has been widely used by nature for non-iridescent structural coloration.

  2. Directional and short-range ordering kinetics in metallic alloys, crystalline and amorphous

    International Nuclear Information System (INIS)

    Hillairet, J.

    1985-01-01

    This presentation describes the methods (resistometric and anelastic) based on analysis of stress-induced directional ordering and short-range ordering and their application to the study of metallic alloys, crystalline and amorphous. It focuses on the determination of the atomic mobility and point defect properties. It discusses also the structural information which can be gained by Zener relaxation studies about the order-disorder transition and self-induced directional ordering phenomena

  3. Neutron diffraction study on the medium and short-range order of ternary chalcogenide glasses

    Czech Academy of Sciences Publication Activity Database

    Neov, S.; Gerasimova, I.; Skordeva, E.; Arsova, D.; Pamukchieva, V.; Mikula, Pavol; Lukáš, Petr; Sonntag, R.

    1999-01-01

    Roč. 34, - (1999), s. 3669-3676 ISSN 0022-2461 R&D Projects: GA ČR GV202/97/K038 Keywords : neutron diffraction * short-range order * chalcogenide glasses Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.786, year: 1999

  4. EXAFS, Determination of Short Range Order and Local Structures in Materials

    NARCIS (Netherlands)

    Koningsberger, D.C.; Prins, R.

    1981-01-01

    Extended X-ray Absorption Fine Structure (EXAFS) is a powerful method of determining short range order and local structures in materials using X-ray photons produced by a synchrotron light source, or in-house by a high intensity rotating anode X-ray generator. The technique has provided valuable

  5. Monte Carlo simulation of atomic short range order and cluster formation in two dimensional model alloys

    International Nuclear Information System (INIS)

    Rojas T, J.; Instituto Peruano de Energia Nuclear, Lima; Manrique C, E.; Torres T, E.

    2002-01-01

    Using monte Carlo simulation have been carried out an atomistic description of the structure and ordering processes in the system Cu-Au in a two-dimensional model. The ABV model of the alloy is a system of N atoms A and B, located in rigid lattice with some vacant sites. In the model we assume pair wise interactions between nearest neighbors with constant ordering energy J = 0,03 eV. The dynamics was introduced by means of a vacancy that exchanges of place with any atom of its neighbors. The simulations were carried out in a square lattice with 1024 and 4096 particles, using periodic boundary conditions to avoid border effects. We calculate the first two parameters of short range order of Warren-Cowley as function of the concentration and temperature. It was also studied the probabilities of formation of different atomic clusters that consist of 9 atoms as function of the concentration of the alloy and temperatures in a wide range of values. In some regions of temperature and concentration it was observed compositional and thermal polymorphism

  6. Study of the effect of short ranged ordering on the magnetism in FeCr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jena, Ambika Prasad, E-mail: apjena@bose.res.in [Department of Condensed Matter and Materials Science, S N Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata 700098 (India); Sanyal, Biplab, E-mail: biplab.sanyal@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Mookerjee, Abhijit, E-mail: abhijit.mookerjee61@gmail.com [Department of Condensed Matter and Materials Science, S N Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake City, Kolkata 700098 (India)

    2014-01-15

    For the study of magnetism in systems where the local environment plays an important role, we propose a marriage between the Monte Carlo simulation and Zunger's special quasi-random structures. We apply this technique on disordered FeCr alloys and show that our estimates of the transition temperature is in good agreement with earlier experiments. - Highlights: • The magnetism in FeCr is sensitively depended on the ordering of the atoms : disordered or with short ranged ordering. • This work uses the SQS technique suggested by Zunger has been used to generate various degrees of short range ordering in FeCr. • The electronic structure and pair energies have been obatined from first principles ASR and Lichtenstein methods. • The effect of chemical ordering on magnetic ordering is studied in detail. • Only those situations where the chemical ordering is complete have been studied.

  7. Study of the effect of short ranged ordering on the magnetism in FeCr alloys

    International Nuclear Information System (INIS)

    Jena, Ambika Prasad; Sanyal, Biplab; Mookerjee, Abhijit

    2014-01-01

    For the study of magnetism in systems where the local environment plays an important role, we propose a marriage between the Monte Carlo simulation and Zunger's special quasi-random structures. We apply this technique on disordered FeCr alloys and show that our estimates of the transition temperature is in good agreement with earlier experiments. - Highlights: • The magnetism in FeCr is sensitively depended on the ordering of the atoms : disordered or with short ranged ordering. • This work uses the SQS technique suggested by Zunger has been used to generate various degrees of short range ordering in FeCr. • The electronic structure and pair energies have been obatined from first principles ASR and Lichtenstein methods. • The effect of chemical ordering on magnetic ordering is studied in detail. • Only those situations where the chemical ordering is complete have been studied

  8. Influence of short range chemical order on density of states in α-ZrNi

    International Nuclear Information System (INIS)

    Duarte Junior, J.

    1986-01-01

    Calculations of the density of electronic states for amorphous alloys of ZrNi and ZrCu with different chemical order degrees, in order to verify the effect of chemical ordering on this property, are presented. The results obtained for ZrCu shown that the density of states at Fermi level do not vary significantly with the ordering. The results for ZrNi shown that the introduction of short range chemical order can decrease significantly the density of states at Fermi level, leading to better agreement with experimental results. (M.C.K.) [pt

  9. Short-range order analysis and some physical properties of InxSe1-x glasses

    International Nuclear Information System (INIS)

    El-Kabany, N.

    2012-01-01

    Bulk In x Se 1-x (with x=5-25 at%) glasses were prepared using the melt-quench technique. Short range order(SRO) was examined by the X-ray diffraction using Cu(k α ) radiation in the wave vector interval 0.28≤k≤6.5 A 0-1 .The SRO parameters have been obtained from the radial distribution function. The inter-atomic distance obtained from the first and second peak are r 1 =0.263 and r 2 =0.460 nm, which is equivalent In-Se and Se-Se bond length. The fundamental structural unit for the studied glasses is In 2 Se 3 pyramid. Using the differential scanning calorimetry (DSC), the crystallization mechanism of In x Se 1-x chalcogenide glass has been studied. The glass transition activation energy (E g ) is 289±0.3 kj/mol.There is a correlation amongst the glass forming ability, bond strength and the number of lone pair electrons. The utility of the Gibbs-Di Marzio relation was achieved by estimating T g theoretically.

  10. Short-range order in amorphous thin films of indium selenides

    International Nuclear Information System (INIS)

    Zakharov, V.P.; Poltavtsev, Yu.G.; Sheremet, G.P.

    1982-01-01

    A structure of the short-range order and a character of interatomic interactions in indium selenides Insub(1-x)Sesub(x) with 0.333 <= x <= 0.75, obtained in the form of amorphous films 0.05-0.80 μm thick are studied using electron diffraction method. It is found out that mostly tetrahedrical coordination of nearest neighbours in the vicinity of indium atoms is characteristic for studied amorphous films, and coordination of selenium atoms is different. Amorphous film with x=0.75 posesses a considereably microheterogeneous structure of the short-range order, which is characterized by the presence of microunclusions of amorphous selenium and atoms of indium, octohedrically coordinated by selenium atoms

  11. Structure of the short-range atomic order of WO3 amorphous films

    International Nuclear Information System (INIS)

    Olevskij, S.S.; Sergeev, M.S.; Tolstikhina, A.L.; Avilov, A.S.; Shkornyakov, S.M.; Semiletov, S.A.

    1984-01-01

    To study the causes of electrochromism manifestation in thin tungsten oxide films, the structure of WO 3 amorphous films has been investigated. The films were obtained by three different methods: by W(CO) 6 tungsten carbonyl pyrolysis, by high-frequency ion-plasma sputtering of a target prepared by WO 3 powder sintering, and by WO 3 powder thermal evaporation. Monocrystalline wafers of silicon and sodium chloride were used as substrates. The structure of short-range order in WO 3 amorphous films varies versus, the method of preparation in compliance with the type of polyhedral elements, (WO 6 , WO 5 ) and with the character of their packing (contacts via edges or vertices). Manifestation of electroc ro mism in WO 3 films prepared by varions methods and having different structure of short-range order is supposed to be realized through various mechanisms. One cannot exclude a potential simultaneous effect of the two coloration mechanisms

  12. Short-range order of amorphous FeNiB alloy after neutron irradiation

    International Nuclear Information System (INIS)

    Miglierini, M.; Sitek, J.; Baluch, S.; Cirak, J.; Lipka, J.

    1990-01-01

    Transmission Moessbauer spectroscopy was used to study irradiation-induced changes in the short-range order of an amorphous Fe 80-x Ni x B 20 alloy. Neutron irradiation led to an increase of the width of a hyperfine field distribution implying atomic rearrangement towards disordering. Changes in a mean value of a HFD and Moessbauer line areas can be associated with a reorientation of spins due to radiation damage. (orig.)

  13. Short-range order in InSb amorphized under ion bombardment

    International Nuclear Information System (INIS)

    Pavlov, P.V.; Tetel'baum, D.I.; Gerasimov, A.I.

    1979-01-01

    The investigation of short-range order is carried out in polycrystal InSb films, irradiated with Ne + ions with E=150 keV and with the 2x10 15 ion/cm 2 dose. The data are obtained testifying to the film amorphization, the cause of which is the defect storage but not the local melting. Stability of the obtained amorphous phase at the room temperature is noted

  14. Changes in structure of the short-range order of the InP melt when heated

    International Nuclear Information System (INIS)

    Glazov, V.M.; Dovletov, K.; Nashel'skij, A.Ya.; Mamedov, M.M.

    1977-01-01

    An investigation of the temperature dependence of the InP viscosity has indicated an ''after-melting'' effect similar to that observed in other A 3 V 5 compounds having a sphalerite structure. The termodynamic parameters of the viscous flow of indium phosphide melt have been calculated, and a suggestion has been made on the loosening of the short-range order structure of the melt during the period preceding solidification. With the similarity in the behaviour of InP and of A 3 Sb compound melts as a basis, a suggestion has been put forward that the influence of the thermal dissociation upon the character of the changes in the short-range order structure directly after transition from the solid to the liquid phase is negligible

  15. Interlayer exchange coupling in Er|Tb superlattices mediated by short range incommensurate Er order

    International Nuclear Information System (INIS)

    Pfuhl, E; Brueckel, T; Voigt, J; Mattauch, S; Korolkov, D

    2010-01-01

    We study the magnetic correlations in Er|Tb superlattices by means of off-specular scattering of polarized neutrons. We show here the co-existence of inhomogeneous magnetic states: i) ferromagnetic order of moments within the Tb layers below 230 K (FM), correlation length of about 10 bilayer, ii) an incommensurate modulated magnetic order, restricted to single Er layers and iii) antiferromagnetic coupling of ferromagnetic layers below 70K (AFC). Polarised off-specular neutron scattering under grazing incidence reveals that i) magnetic fluctuations appear when the sample is cooled below 70 K, ii) these fluctuations lead to AFC, when the sample is cooled to 10 K, which iii) persists, when the sample is subsequently heated up to 45 K, while the order is not present during the cooling cycle. Also the short range incommensurate order changes accordingly, implying that the magnetic order in the Er layers mediates the interlayer coupling between ferromagnetic Tb layers.

  16. A first-principles study of short range order in Cu-Zn

    International Nuclear Information System (INIS)

    Slutter, M.; Turchi, P.E.A.; Johnson, D.D.; Nicholson, D.M.; Stocks, G.M.; Pinski, F.J.

    1990-01-01

    Recently, measurements of short-range order (SRO) diffuse neutron scattering intensity have been performed on quenched Cu-Zn alloys with 22.4 to 31.1 atomic percent (a/o) Zn, and pair interactions were obtained by inverse Monte Carlo simulation. These results are compared to SRO intensities and effective pair interactions obtained from first-principles electronic structure calculations. The theoretical SRO intensities were calculated with the cluster variation method (CVM) in the tetrahedron-octahedron approximation with first-principles pain interactions as input. More generally, phase stability in the Cu-Zn alloy system is discussed, using ab-initio energetic properties

  17. Short-range order and local conservation of quantum numbers in multiparticle production

    International Nuclear Information System (INIS)

    Le Bellac, M.

    1976-01-01

    These lectures discuss the implications of the hypotheses of short-range order (SRO) and local conservation of quantum numbers (LCQN) for multiple production of elementary particles at high energies. The consequences of SRO for semi-inclusive correlations and the distribution of rapidity gaps are derived, essentially in the framework of the cluster model. Then the experimental status of local conservation of charge and transverse momentum is reviewed. Finally, by making use of the unitarity relation, it is shown that LCQN has important consequences for the elastic amplitude. The derivation is given both in a model-independent way, and in specific multiperiheral models. (Author)

  18. EXAFS study of short range order in Fe-Zr amorphous alloys

    International Nuclear Information System (INIS)

    Fernandez-Gubieda, M.L.; Gorria, P.; Barandiaran, J.M.; Barquin, L.F.

    1995-01-01

    Room temperature X-ray absorption spectra on Fe K-edge have been performed in Fe 100-x-y Zr x B y and Fe 86 Zr 7 Cu 1 B 6 alloys (x=7, 7.7, 9; y=0, 2, 4, 6). Fe-Fe coordination number and interatomic distances do not change in any sample. However, small changes in the Fe-Zr short range order, which could explain the evolution of the magnetic properties, have been observed. (orig.)

  19. Distinct Short-Range Order Is Inherent to Small Amorphous Calcium Carbonate Clusters (<2 nm)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Shengtong [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany; School of Chemical Engineering, State Key Laboratory of Chemical Engineering, Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, East China University of Science and Technology, 130 Meilong Road Shanghai 200237 P.R. China; Chevrier, Daniel M. [Department of Chemistry and Institute for Research in Materials, Dalhousie University, Halifax Nova Scotia B3H 4R2 Canada; Zhang, Peng [Department of Chemistry and Institute for Research in Materials, Dalhousie University, Halifax Nova Scotia B3H 4R2 Canada; Gebauer, Denis [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany; Cölfen, Helmut [Physical Chemistry, University of Konstanz, Universitätsstrasse 10 78457 Konstanz Germany

    2016-09-09

    Amorphous intermediate phases are vital precursors in the crystallization of many biogenic minerals. While inherent short-range orders have been found in amorphous calcium carbonates (ACCs) relating to different crystalline forms, it has never been clarified experimentally whether such orders already exist in very small clusters less than 2 nm in size. Here, we studied the stability and structure of 10,12-pentacosadiynoic acid (PCDA) protected ACC clusters with a core size of ca. 1.4 nm consisting of only seven CaCO3 units. Ligand concentration and structure are shown to be key factors in stabilizing the ACC clusters. More importantly, even in such small CaCO3 entities, a proto-calcite short-range order can be identified but with a relatively high degree of disorder that arises from the very small size of the CaCO3 core. Our findings support the notion of a structural link between prenucleation clusters, amorphous intermediates, and final crystalline polymorphs, which appears central to the understanding of polymorph selection.

  20. Evolution of short range order in Ar: Liquid to glass and solid transitions-A computational study

    Science.gov (United States)

    Shor, Stanislav; Yahel, Eyal; Makov, Guy

    2018-04-01

    The evolution of the short range order (SRO) as a function of temperature in a Lennard-Jones model liquid with Ar parameters was determined and juxtaposed with thermodynamic and kinetic properties obtained as the liquid was cooled (heated) and transformed between crystalline solid or glassy states and an undercooled liquid. The Lennard-Jones system was studied by non-equilibrium molecular dynamics simulations of large supercells (approximately 20000 atoms) rapidly cooled or heated at selected quenching rates and at constant pressure. The liquid to solid transition was identified by discontinuities in the atomic volume and molar enthalpy; the glass transition temperature range was identified from the temperature dependence of the self-diffusion. The SRO was studied within the quasi-crystalline model (QCM) framework and compared with the Steinhardt bond order parameters. Within the QCM it was found that the SRO evolves from a bcc-like order in the liquid through a bct-like short range order (c/a=1.2) in the supercooled liquid which persists into the glass and finally to a fcc-like ordering in the crystalline solid. The variation of the SRO that results from the QCM compares well with that obtained with Steinhardt's bond order parameters. The hypothesis of icosahedral order in liquids and glasses is not supported by our results.

  1. Intermediate- and short-range order in phosphorus-selenium glasses

    International Nuclear Information System (INIS)

    Bytchkov, Aleksei; Hennet, Louis; Price, David L.; Miloshova, Mariana; Bychkov, Eugene; Kohara, Shinji

    2011-01-01

    State-of-the-art neutron and x-ray diffraction measurements have been performed to provide a definitive picture of the intermediate- and short-range structures of P x Se 1-x glasses spanning two glass regions, x 0.025-0.54 and 0.64-0.84. Liquid P 4 Se 3 and amorphous red P and Se were also measured. Detailed information was obtained about the development with increasing phosphorous concentration of intermediate-range order on the length scale ∼6 A ring , based on the behavior of the first sharp diffraction peak. Attention is also paid to the feature in the structure factor at 7.5 A ring -1 , identified in earlier numerical simulations, provides further evidence of the existence of molecular units. The real-space transforms yield a reliable statistical picture of the changing short-range order as x increases, using the information about types and concentrations of local structural units provided by previous NMR measurements to interpret the trends observed.

  2. Polyamorphism and substructure of short-range order in amorphous boron films

    International Nuclear Information System (INIS)

    Palatnik, L.S.; Nechitajlo, A.A.; Koz'ma, A.A.

    1981-01-01

    The structure and substructure of boron amorphous films are studied in detail. Amorphous condensate of Bsup(a) boron is built of the same (but only disorientedly located) 12 B icosahedrons as boron crystalline modifications: B 105 -equilibrium β-rhombic, metastable: B 50 -tetragonal, B 12 -α-rhombohedral Coordination number for Bsup(a) (Z 1 =6.4) is lower than in B 105 (Z 1 =6.6) but higher than in B 50 modification (Z 1 =6.1). In crystalline modifications B 105 , B 50 , B 12 coordination numbers ω in first coordination spheres of icosahedrons are equal to ν 105 =6+4.6=10.6; ν 50 =10+3=14; ν 12 =6 respectively. Both amorphous modifications of boron Bsub(1)sup(a) and Bsub(15)sup(a) are analogs to B 50 in respect of the short-range order of icosahedron location. The difference between them is in ''substructure'' of short-range order: part of boron atoms (approximately 12%) do not occupy the vertices (so that vacancies appear) and enter the emptinesses between icosahedrons. In other words, the structure B 50 is the model basis of both amorphous phases [ru

  3. Unitarity corrections to short-range order long-range rapidity correlations

    CERN Document Server

    Capella, A

    1978-01-01

    Although the effective hadronic forces have short range in rapidity space, one nevertheless expects long-range dynamical correlations induced by unitarity constraints. This paper contains a thorough discussion of long-range rapidity correlations in high-multiplicity events. In particular, the authors analyze in detail the forward- backward multiplicity correlations, measured recently in the whole CERN ISR energy range. They find from these data that the normalized variance of the number n of exchanged cut Pomerons, ((n/(n)-1)/sup 2/) , is most probably in the range 0.32 to 0.36. They show that such a number is obtained from Reggeon theory in the eikonal approximation. The authors also predict a very specific violation of local compensation of charge in multiparticle events: The violation should appear in the fourth-order zone correlation function and is absent in the second-order correlation function, the only one measured until now. (48 refs).

  4. Direct separation of short range order in intermixed nanocrystalline and amorphous phases

    International Nuclear Information System (INIS)

    Frenkel, Anatoly I.; Kolobov, Alexander V.; Robinson, Ian K.; Cross, Julie O.; Maeda, Yoshihito; Bouldin, Charles E.

    2002-01-01

    Diffraction anomalous fine-structure (DAFS) and extended x-ray absorption fine-structure (EXAFS) measurements were combined to determine short range order (SRO) about a single atomic type in a sample of mixed amorphous and nanocrystalline phases of germanium. EXAFS yields information about the SRO of all Ge atoms in the sample, while DAFS determines the SRO of only the ordered fraction. We determine that the first-shell distance distribution is bimodal; the nanocrystalline distance is the same as the bulk crystal, to within 0.01(2) A ring , but the mean amorphous Ge-Ge bond length is expanded by 0.076(19) Angstrom. This approach can be applied to many systems of mixed amorphous and nanocrystalline phases

  5. Short-range order studies in nonstoichiometric transition metal carbides and nitrides by neutron diffuse scattering

    International Nuclear Information System (INIS)

    Priem, Thierry

    1988-01-01

    Short-range order in non-stoichiometric transition metal carbides and nitrides (TiN 0.82 , TiC 0.64 , TiC 0.76 , NbC 0.73 and NbC 0.83 ) was investigated by thermal neutron diffuse scattering on G4-4 (L.L.B - Saclay) and D10 (I.L.L. Grenoble) spectrometers. From experimental measurements, we have found that metalloid vacancies (carbon or nitrogen) prefer the f.c.c. third neighbour positions. Ordering interaction energies were calculated within the Ising model framework by three approximations: mean field (Clapp and Moss formula), Monte-Carlo simulation, Cluster variation Method. The energies obtained by the two latter methods are very close, and in qualitative agreement with theoretical values calculated from the band structure. Theoretical phase diagrams were calculated from these ordering energies for TiN x and TiC x ; three ordered structures were predicted, corresponding to compositions Ti 6 N 5 Ti 2 C and Ti 3 C 2 . On the other hand, atomic displacements are induced by vacancies. The metal first neighbours were found to move away from a vacancy, whereas the second neighbours move close to it. Near neighbour atomic displacements were theoretically determined by the lattice statics formalism with results in good agreement with experiment. (author) [fr

  6. Large magnetoelectric coupling in magnetically short-range ordered Bi₅Ti₃FeO₁₅ film.

    Science.gov (United States)

    Zhao, Hongyang; Kimura, Hideo; Cheng, Zhenxiang; Osada, Minoru; Wang, Jianli; Wang, Xiaolin; Dou, Shixue; Liu, Yan; Yu, Jianding; Matsumoto, Takao; Tohei, Tetsuya; Shibata, Naoya; Ikuhara, Yuichi

    2014-06-11

    Multiferroic materials, which offer the possibility of manipulating the magnetic state by an electric field or vice versa, are of great current interest. However, single-phase materials with such cross-coupling properties at room temperature exist rarely in nature; new design of nano-engineered thin films with a strong magneto-electric coupling is a fundamental challenge. Here we demonstrate a robust room-temperature magneto-electric coupling in a bismuth-layer-structured ferroelectric Bi₅Ti₃FeO₁₅ with high ferroelectric Curie temperature of ~1000 K. Bi₅Ti₃FeO₁₅ thin films grown by pulsed laser deposition are single-phase layered perovskit with nearly (00l)-orientation. Room-temperature multiferroic behavior is demonstrated by a large modulation in magneto-polarization and magneto-dielectric responses. Local structural characterizations by transmission electron microscopy and Mössbauer spectroscopy reveal the existence of Fe-rich nanodomains, which cause a short-range magnetic ordering at ~620 K. In Bi₅Ti₃FeO₁₅ with a stable ferroelectric order, the spin canting of magnetic-ion-based nanodomains via the Dzyaloshinskii-Moriya interaction might yield a robust magneto-electric coupling of ~400 mV/Oe·cm even at room temperature.

  7. Short-range second order screened exchange correction to RPA correlation energies

    Science.gov (United States)

    Beuerle, Matthias; Ochsenfeld, Christian

    2017-11-01

    Direct random phase approximation (RPA) correlation energies have become increasingly popular as a post-Kohn-Sham correction, due to significant improvements over DFT calculations for properties such as long-range dispersion effects, which are problematic in conventional density functional theory. On the other hand, RPA still has various weaknesses, such as unsatisfactory results for non-isogyric processes. This can in parts be attributed to the self-correlation present in RPA correlation energies, leading to significant self-interaction errors. Therefore a variety of schemes have been devised to include exchange in the calculation of RPA correlation energies in order to correct this shortcoming. One of the most popular RPA plus exchange schemes is the second order screened exchange (SOSEX) correction. RPA + SOSEX delivers more accurate absolute correlation energies and also improves upon RPA for non-isogyric processes. On the other hand, RPA + SOSEX barrier heights are worse than those obtained from plain RPA calculations. To combine the benefits of RPA correlation energies and the SOSEX correction, we introduce a short-range RPA + SOSEX correction. Proof of concept calculations and benchmarks showing the advantages of our method are presented.

  8. Short-range order in alloys of nickel with the elements of group VIII of the periodic table

    International Nuclear Information System (INIS)

    Khwaja, F.A.

    1981-08-01

    Experimental measurements of the diffuse X-ray scattering intensity were performed on alloys of Ni with Rh and Os. The atomic short-range order (SRO) parameters αsub(i) and the size-effect parameters βsub(i) were calculated from these measurements. It is established that SRO and size-effect exist in Ni-Rh and Ni-Os alloys analogously as in a few other alloys of Ni with the elements of group VIII of the periodic table. The experimental data was interpreted theoretically by calculating the interaction energies from the pseudo-potentials and the effective valencies of the individual components of the systems studied. It was found that theoretically calculated values of the interaction energies for these alloys are inconsistent with the experimentally determined sign of the SRO parameter. (author)

  9. Short-Range-Order for fcc-based Binary Alloys Revisited from Microscopic Geometry

    Science.gov (United States)

    Yuge, Koretaka

    2018-04-01

    Short-range order (SRO) in disordered alloys is typically interpreted as competition between chemical effect of negative (or positive) energy gain by mixing constituent elements and geometric effects comes from difference in effective atomic radius. Although we have a number of theoretical approaches to quantitatively estimate SRO at given temperatures, it is still unclear to systematically understand trends in SRO for binary alloys in terms of geometric character, e.g., effective atomic radius for constituents. Since chemical effect plays significant role on SRO, it has been believed that purely geometric character cannot capture the SRO trends. Despite these considerations, based on the density functional theory (DFT) calculations on fcc-based 28 equiatomic binary alloys, we find that while conventional Goldschmidt or DFT-based atomic radius for constituents have no significant correlation with SRO, atomic radius for specially selected structure, constructed purely from information about underlying lattice, can successfully capture the magnitude of SRO. These facts strongly indicate that purely geometric information of the system plays central role to determine characteristic disordered structure.

  10. Short-range order in the quantum XXZ honeycomb lattice material BaCo2(PO4)2

    Science.gov (United States)

    Nair, Harikrishnan S.; Brown, J. M.; Coldren, E.; Hester, G.; Gelfand, M. P.; Podlesnyak, A.; Huang, Q.; Ross, K. A.

    2018-04-01

    We present observations of highly frustrated quasi-two-dimensional (2D) magnetic correlations in the honeycomb lattice layers of the Seff =1 /2 compound γ -BaCo2(PO4)2 (γ -BCPO). Specific heat shows a broad peak comprised of two weak kink features at TN 1˜6 K and TN 2˜3.5 K, the relative weights of which can be modified by sample annealing. Neutron powder diffraction measurements reveal short range quasi-2D order that is established below TN 1 and TN 2, at which two separate, incompatible, short range magnetic orders onset: commensurate antiferromagnetic correlations with correlation length ξc=60 ±2 Å (TN 1) and in quasi-2D helical domains with ξh=350 ±11 Å (TN 2). The ac magnetic susceptibility response lacks frequency dependence, ruling out spin freezing. Inelastic neutron scattering data on γ -BCPO is compared with linear spin wave theory, and two separate parameter regions of the XXZ J1-J2-J3 model with ferromagnetic nearest-neighbor exchange J1 are favored, both near regions of high classical degeneracy. High energy coherent excitations (˜10 meV) persist up to at least 40 K, suggesting strong in-plane correlations persist above TN. These data show that γ -BCPO is a rare highly frustrated, quasi-2D Seff =1 /2 honeycomb lattice material which resists long range magnetic order and spin freezing.

  11. Short-Range-Order Mineral Physical Protection On Black Carbon Stabilization

    Science.gov (United States)

    Liang, B.; Weng, Y. T.; Wang, C. C.; Song, Y. F.; Lehmann, J.; Wang, C. H.

    2015-12-01

    Soil organic matter is one of the largest reservoirs in global carbon cycle, and black carbon (BC) represents a chemical resistant component. Black C plays an important role in global climate change. Generally considered recalcitrant due to high aromaticity, the reactive surface and functional groups of BC are crucial for carbon sequestration in soils. Mineral sorption and physical protection is an important mechanism for BC long term stabilization and sequestration in environments. Previous studies on mineral protection of BC were limited to analysis techniques in two-dimensions, for example, by SEM, TEM, and NanoSIMS. Little is known about the scope of organo-mineral association, the in-situ distribution and forms of minerals, and the ultimate interplay of BC and minerals. The aim of this study is to investigate the three-dimensional interaction of organic C and minerals in submicron scale using synchrotron-based Transmission X-ray Microcopy (TXM) and Fourier-Transform Infrared Spectroscopy (FTIR). Abundant poorly-crystallined nano-minerals particles were observed. These short-range-order (SRO) minerals also aggregate into clusters and sheets, and form envelops-like structures on the surface of BC. On top of large surface contact area, the intimate interplay between BC and minerals reinforces the stability of both organic C and minerals, resulting from chemical bonding through cation bridging and ligand exchange. The mineral protection enhances BC stabilization and sequestration and lowers its bioavailability in environment. The results suggest that mineral physical protection for BC sequestration may be more important than previous understanding.

  12. Fungal biomineralization of montmorillonite and goethite to short-range-ordered minerals

    Science.gov (United States)

    Li, Huan; Hu, Shuijin; Polizzotto, Matthew L.; Chang, Xiaoli; Shen, Qirong; Ran, Wei; Yu, Guanghui

    2016-10-01

    Highly reactive nano-scale minerals, e.g., short-range-ordered minerals (SROs) and other nanoparticles, play an important role in soil carbon (C) retention. Yet, the mechanisms that govern biomineralization from bulk minerals to highly reactive nano-scale minerals remain largely unexplored, which critically hinders our efforts toward managing nano-scale minerals for soil C retention. Here we report the results from a study that explores structural changes during Aspergillus fumigatus Z5 transformation of montmorillonite and goethite to SROs. We examined the morphology and structure of nano-scale minerals, using high-resolution transmission electron microscopy, time-resolved solid-state 27Al and 29Si NMR, and Fe K-edge X-ray absorption fine structure spectroscopy combined with two dimensional correlation spectroscopy (2D COS) analysis. Our results showed that after a 48-h cultivation of montmorillonite and goethite with Z5, new biogenic intracellular and extracellular reactive nano-scale minerals with a size of 3-5 nm became abundant. Analysis of 2D COS further suggested that montmorillonite and goethite were the precursors of the dominant biogenic nano-scale minerals. Carbon 1s near edge X-ray absorption fine structure (NEXAFS) spectra and their deconvolution results demonstrated that during fungus Z5 growth, carboxylic C (288.4-289.1 eV) was the dominant organic group, accounting for approximately 34% and 59% in the medium and aggregates, respectively. This result suggested that high percentage of the production of organic acids during the growth of Z5 was the driving factor for structural changes during biomineralization. This is, to the best of our knowledge, the first report of the structural characterization of nano-scale minerals by 2D COS, highlighting its potential to elucidate biomineralization pathways and thus identify the precursors of nano-scale minerals.

  13. Short range order and phase separation in Ti-rich Ti-Al alloys

    International Nuclear Information System (INIS)

    Liew, H.J.

    1999-01-01

    of the reaction over a range of scales, from the atomic level on which order occurs through to large scale precipitates. Ti-15at%Al displays a phase separation mechanism involving both ordering and chemical phase decomposition which occurs in a time and temperature range that is readily accessible experimentally. Hence this alloy is an appropriate model system on which to conduct fundamental investigations into a complex decomposition mechanism and its kinetics. Both experimental and modelling results show that short range order develops rapidly in the alloy, and is followed by the formation and growth of congruent long range ordered regions of DO 19 structure. At a later stage composition variations form and increase in amplitude through a spinodal mechanism. From these findings, it cannot be ruled out that the observed decomposition sequence is due solely to the kinetics of ordering being more rapid than those of chemical phase separation. However, there are some indications which suggest that a thermodynamic criterion is operating, such that the onset of chemical phase separation occurs only after ordering has been achieved to some extent. The observed mechanism is fully consistent in appearance with the class of reactions known as conditional spinodals. (author)

  14. Short Range-Ordered Minerals: Insight into Aqueous Alteration Processes on Mars

    Science.gov (United States)

    Ming, Douglas W.; Morris, R. V.; Golden, D. C.

    2011-01-01

    Short range-ordered (SRO) aluminosilicates (e.g., allophane) and nanophase ferric oxides (npOx) are common SRO minerals derived during aqueous alteration of basaltic materials. NpOx refers to poorly crystalline or amorphous alteration products that can be any combination of superparamagnetic hematite and/or goethite, akaganeite, schwertmannite, ferrihydrite, iddingsite, and nanometer-sized ferric oxide particles that pigment palagonitic tephra. Nearly 30 years ago, SRO phases were suggested as alteration phases on Mars based on similar spectral properties for altered basaltic tephra on the slopes of Mauna Kea in Hawaii and Martian bright regions measured by Earth-based telescopes. Detailed characterization of altered basaltic tephra on Mauna Kea have identified a variety of alteration phases including allophane, npOx, hisingerite, jarosite, alunite, hematite, goethite, ferrihydrite, halloysite, kaolinite, smectite, and zeolites. The presence of npOx and other Fe-bearing minerals (jarosite, hematite, goethite) was confirmed by the M ssbauer Spectrometer onboard the Mars Exploration Rovers. Although the presence of allophane has not been definitely identified on Mars robotic missions, chemical analysis by the Spirit and Opportunity rovers and thermal infrared spectral orbital measurements suggest the presence of allophane or allophane-like phases on Mars. SRO phases form under a variety of environmental conditions on Earth ranging from cold and arid to warm and humid, including hydrothermal conditions. The formation of SRO aluminosilicates such as allophane (and crystalline halloysite) from basaltic material is controlled by several key factors including activity of water, extent of leaching, Si activity in solution, and available Al. Generally, a low leaching index (e.g., wet-dry cycles) and slightly acidic to alkaline conditions are necessary. NpOx generally form under aqueous oxidative weathering conditions, although thermal oxidative alteration may occasional be

  15. Higher-order glass-transition singularities in systems with short-ranged attractive potentials

    International Nuclear Information System (INIS)

    Goetze, W; Sperl, M

    2003-01-01

    Within the mode-coupling theory for the evolution of structural relaxation, the A 4 -glass-transition singularities are identified for systems of particles interacting with a hard-sphere repulsion complemented by different short-ranged potentials: Baxter's singular potential regularized by a large-wavevector cut-off, a model for the Asakura-Oosawa depletion attraction, a triangular potential, a Yukawa attraction, and a square-well potential. The regular potentials yield critical packing fractions, critical Debye-Waller factors, and critical amplitudes very close to each other. The elastic moduli and the particle localization lengths for corresponding states of the Yukawa system and the square-well system may differ by up to 20 and 10%, respectively

  16. Short-range order clustering in BCC Fe-Mn alloys induced by severe plastic deformation

    Science.gov (United States)

    Shabashov, V. A.; Kozlov, K. A.; Sagaradze, V. V.; Nikolaev, A. L.; Lyashkov, K. A.; Semyonkin, V. A.; Voronin, V. I.

    2018-03-01

    The effect of severe plastic deformation, namely, high-pressure torsion (HPT) at different temperatures and ball milling (BM) at different time intervals, has been investigated by means of Mössbauer spectroscopy in Fe100-xMnx (x = 4.1, 6.8, 9) alloys. Deformation affects the short-range clustering (SRC) in BCC lattice. Two processes occur: destruction of SRC by moving dislocations and enhancement of the SRC by migration of non-equilibrium defects. Destruction of SRC prevails during HPT at 80-293 K; whereas enhancement of SRC dominates at 473-573 K. BM starts enhancing the SRC formation at as low as 293 K due to local heating at impacts. The efficiency of HPT in terms of enhancing SRC increases with increasing temperature. The authors suppose that at low temperatures, a significant fraction of vacancies are excluded from enhancing SRC because of formation of mobile bi- and tri-vacancies having low efficiency of enhancing SRC as compared to that of mono vacancies. Milling of BCC Fe100-xMnx alloys stabilises the BCC phase with respect to α → γ transition at subsequent isothermal annealing because of a high degree of work hardening and formation of composition inhomogeneity.

  17. Short-range order in Fe-based metallic glasses: Wide-angle X-ray scattering studies

    International Nuclear Information System (INIS)

    Babilas, Rafał; Hawełek, Łukasz; Burian, Andrzej

    2014-01-01

    The local atomic structure of the Fe 80 B 20 , Fe 70 Nb 10 B 20 and Fe 62 Nb 8 B 30 glasses prepared in the form of ribbons has been studied by wide-angle X-ray scattering. Structural information about the amorphous ribbons has been derived from analysis of the radial distribution functions using the least-squares curve-fitting method. The obtained structural parameters indicate that Fe–Fe, Fe–B, Fe–Nb and Nb–B contributions are involved in the near-neighbor coordination spheres. The possible similarities of the local atomic arrangement in the investigated glasses and the crystalline Fe 3 B, Fe 23 B 6 and bcc Fe structures are also discussed. - Graphical abstract: Pair distribution functions (a) and best-fit model and experimental radial distribution functions for Fe 80 B 20 (b), Fe 70 Nb 10 B 20 (c) and Fe 62 Nb 8 B 30 (d) metallic glasses. - Highlights: • The short-range ordering in the Fe-based metallic glasses is presented. • The results of RDF function have been analyzed using the least-squares method. • The Fe–Fe, Fe–B, Fe–Nb or Nb–B contributions are involved in coordination spheres. • The structural unit is distorted triangular prism containing B, Fe or Nb atoms. • Similarities of atomic arrangement in glassy and crystalline structures are discussed

  18. Thermal ageing and short-range ordering of Alloy 690 between 350 and 550 °C

    Energy Technology Data Exchange (ETDEWEB)

    Mouginot, Roman, E-mail: roman.mouginot@aalto.fi [Aalto University School of Engineering, Department of Mechanical Engineering, Otakaari 4, 02150 Espoo (Finland); Sarikka, Teemu [Aalto University School of Engineering, Department of Mechanical Engineering, Otakaari 4, 02150 Espoo (Finland); Heikkilä, Mikko [University of Helsinki, Laboratory of Inorganic Chemistry, A.I.Virtasen Aukio 1, 00560 Helsinki (Finland); Ivanchenko, Mykola; Ehrnstén, Ulla [VTT Technical Research Centre of Finland LTD, Kemistintie 3, 02150 Espoo (Finland); Kim, Young Suk; Kim, Sung Soo [Korea Atomic Energy Research Institute, Daedeok-Daero, 989-111, Yuseong, Daejeon, 34057 (Korea, Republic of); Hänninen, Hannu [Aalto University School of Engineering, Department of Mechanical Engineering, Otakaari 4, 02150 Espoo (Finland)

    2017-03-15

    Thermal ageing of Alloy 690 triggers an intergranular (IG) carbide precipitation and is known to promote an ordering reaction causing lattice contraction. It may affect the long-term primary water stress corrosion cracking (PWSCC) resistance of pressurized water reactor (PWR) components. Four conditions of Alloy 690 (solution annealed, cold-rolled and/or heat-treated) were aged between 350 and 550 °C for 10 000 h and characterized. Although no direct observation of ordering was made, variations in hardness and lattice parameter were attributed to the formation of short-range ordering (SRO) in all conditions with a peak level at 420 °C, consistent with the literature. Prior heat treatment induced ordering before thermal ageing. At higher temperatures, stress relaxation, recrystallization and α-Cr precipitation were observed in the cold-worked samples, while a disordering reaction was inferred in all samples based on a decrease in hardness. IG precipitation of M{sub 23}C{sub 6} carbides increased with increasing ageing temperature in all conditions, as well as diffusion-induced grain boundary migration (DIGM). - Highlights: • SRO was suggested in Alloy 690 with 9.18 wt% Fe after thermal ageing at 350, 420 and 475 °C. • Prior thermal treatment promoted SRO before ageing. • Cold work led to recrystallization and precipitation of α-Cr upon ageing at 550 °C. • Thermal ageing promoted IG precipitation of Cr-rich M{sub 23}C{sub 6} carbides and DIGM.

  19. Correlation of optical energy gap with the nearest neighbour short range order in amorphous V2O5 films

    International Nuclear Information System (INIS)

    Dhawan, Sahil; Vedeshwar, Agnikumar G; Tandon, R P

    2011-01-01

    The optical and structural properties of well characterized vacuum-evaporated amorphous V 2 O 5 films were studied in the thickness range 5-500 nm. The structural analyses show that V-O, O-O and V-V nearest neighbour distances defining the short range order vary nonlinearly with film thickness. The optical absorption shows thickness-dependent energy gap (E g ) and the nonlinear behaviour of thickness-dependent E g is similar to that of nearest neighbour distance with film thickness. The E g correlates linearly very well with all the three nearest neighbour distances. The variation of E g with film thickness is attributed to the residual stress in the film which causes the changes in short range order. The change in E g corresponding to the change in V-O distance was found to be 35 eV nm -1 . This change is almost three times of that with V-V distance.

  20. Investigation into short-range order, electric conductivity and optical absorption edge of indium selenide thin amorphous films

    International Nuclear Information System (INIS)

    Bilyj, M.N.; Didyk, G.V.; Stetsiv, Ya.I.; Yurechko, R.Ya.

    1980-01-01

    Thin amorphous films of InSe have been obtained by the method of discrete vacuum evaporation of about 10 -2 Pa. The short-range order is investigated according to the radial distribution curves. The temperature and film thickness are shown to affect the character of conductivity. The width of the forbidden band determined by the fundamental absorption edge is found to depend on the time of film annealing

  1. Electron irradiation effect on short-range ordering in Cu-Al and Ag-Al alloys

    International Nuclear Information System (INIS)

    Kulish, N.P.; Mel'nikova, N.A.; Petrenko, P.V.; Ryabishchuk, A.L.; Tatarov, A.A.

    1990-01-01

    Method of X-ray diffuse scattering is used to study short-range order variation in Cu-Al and Ag-Al alloys under radiation effect and the following heat treatment. Irradiation was carried out at -40 deg C by 1.6 MeV electrons, fluence of 5x10 7 cm -2 and 0.5 MeV gamma-rays, the dose being 10 7 pH

  2. Natural gels: crystal-chemistry of short range ordered components in Al, Fe, and Si systems

    International Nuclear Information System (INIS)

    Ildefonse, Ph.; Calas, G.

    1997-01-01

    In this review, the most important inorganic natural gels are presented: opal, aluminosilicate (allophanes) and hydrous iron oxides and silicates. It is demonstrated that natural gels are ordered at the atomic scale. In allophanes, Al is distributed between octahedral and tetrahedral sites. The amount of Al increases as Al/Si ratio decreases. Si-rich allophane have a local structure around Al and Si very different of that is known in kaolinite or halloysite. Transformation of Si-rich allophanes to crystallized minerals implies dissolution-recrystallization processes. On the contrary, in iron silicate with Fe/Si = 0.72, Si and Fe environments are close to those found in nontronite. The gel transformation to Fe-smectite may occur by long range ordering during ageing. In ferric silicate gels, the similarity of local structure around Fe in poorly ordered precursors and what is known in crystallized minerals suggests a solid transformation during ageing. This difference between iron and aluminium is mainly due to the ability of Al to enter both tetrahedral and octahedral sites, while the affinity of iron for octahedral sites is higher at low temperature

  3. Mixed hyperfine interaction - a tool to investigate the short range order and the strange magnetic behaviour of amorphous Fe-based binary alloys

    International Nuclear Information System (INIS)

    Fries, S.M.; Crummenauer, J.; Gonser, U.; Schaaf, P.; Chien, C.L.

    1989-01-01

    The Moessbauer study of the mixed magnetic dipole and electric quadrupole interaction in the paramagnetic state of amorphous Fe-Zr and Fe-Hf alloys is presented. Strong evidence for chemical short range order of the iron-pure alloys is found. The hyperfine parameters of the iron-rich alloys are marked by a complex applied field and temperature dependence, suggesting a not negligible spin-correlation well above Tc. (orig.)

  4. Chemical short range order and magnetic correction in liquid manganese–gallium zero alloy

    Energy Technology Data Exchange (ETDEWEB)

    Grosdidier, B. [Laboratoire de Chimie Physique – Approche Multi-Echelle des Milieux Complexes, Institut Jean Bariol, Université de Lorraine, Institut de Chimie, Physique et Matériaux, 1 Bd Arago, 57078 Metz Cedex 3 (France); Ben Abdellah, A. [Laboratoire de Chimie Physique – Approche Multi-Echelle des Milieux Complexes, Institut Jean Bariol, Université de Lorraine, Institut de Chimie, Physique et Matériaux, 1 Bd Arago, 57078 Metz Cedex 3 (France); Innovation and Management of Industrial Systems, Abdelmalek Essaadi University, College of Sciences and Techniques of Tangier , P.O. Box 416, Postal code 90000, Tangier (Morocco); Université Internationale de Rabat, Parc Technopolis Rabat-Shore, 11100 Sala El Jadida (Morocco); Osman, S.M., E-mail: osm@squ.edu.om [Physics Department, College of Science, Sultan Qaboos University, P.O. Box 36, Postal Code 123, Al-Khod, Muscat (Oman); Ataati, J. [Innovation and Management of Industrial Systems, Abdelmalek Essaadi University, College of Sciences and Techniques of Tangier, P.O. Box 416, Postal code 90000, Tangier (Morocco); Gasser, J.G. [Laboratoire de Chimie Physique – Approche Multi-Echelle des Milieux Complexes, Institut Jean Bariol, Université de Lorraine, Institut de Chimie, Physique et Matériaux, 1 Bd Arago, 57078 Metz Cedex 3 (France)

    2015-12-15

    The Mn{sub 66}Ga{sub 34} alloy at this particular composition is known to be zero alloy in which the linear combination of the two neutron scattering lengths weighted by the atomic compositions vanish. Thus for this specific concentration, the effect of the partial structure factors S{sub NN} and S{sub NC} is cancelled by a weighted term, which value is zero. Then the measured total structure factor S(q) gives directly the concentration–concentration structure factor S{sub CC}(q). We present here the first experimental results of neutron diffraction on the Mn{sub 66}Ga{sub 34} “null matrix alloy” at 1050 °C. The main peak of the experimental S{sub CC}(q) gives a strong evidence of a hetero-atomic chemical order in this coordinated alloy. This order also appears in real space radial distribution function which is calculated by the Fourier transform of the structure factor. The degree of hetero-coordination is discussed together with other manganese-polyvalent alloys. However manganese also shows abnormal magnetic scattering in the alloy structure factor which must be corrected. This correction gives an experimental information on the mean effective spin of manganese in this liquid alloy. We present the first critical theoretical calculations of the magnetic correction factor in Mn–Ga zero-alloy based on our accurate experimental measurements of S{sub CC}(q).

  5. Formation and transformation of a short range ordered iron carbonate precursor

    DEFF Research Database (Denmark)

    Dideriksen, Knud; Frandsen, Cathrine; Bovet, Nicolas

    2015-01-01

    (II) with varying pH produced broad peaks in X-ray diffraction and contained dominantly Fe and CO3 when probed with X-ray photoelectron spectroscopy. Reduced pair distribution function (PDF) analysis shows only peaks corresponding to interatomic distances below 15Å, reflecting a material with no long range...... structural order. Moreover, PDF peak positions differ from those for known iron carbonates and hydroxides. Mössbauer spectra also deviate from those expected for known iron carbonates and suggest a less crystalline structure. These data show that a previously unidentified iron carbonate precursor phase...... formed. Its coherent scattering domains determined from PDF analysis are slightly larger than for amorphous calcium carbonate, suggesting that the precursor could be nanocrystalline. Replica exchange molecular dynamics simulations of Fe-carbonate polynuclear complexes yield PDF peak positions that agree...

  6. A NEUTRON DIFFRACTION DETERMINATION OF SHORT RANGE ORDER IN A Ni63.7Zr36.3 GLASS

    OpenAIRE

    Bellissent , R.; Bigot , J.; Calvayrac , Y.; Lefebvre , S.; Quivy , A.

    1985-01-01

    A precise determination of the three partial structure factors for the eutectic composition Ni63.7Zr36.3 has been carried out using neutron diffraction on three isotopically substituted glasses. The use of a "zero alloy" yields a direct determination of the Bhatia-Thornton structure factor SCC. Evidence for the existence of strong chemical short-range order and a clear size effect is obtained. Due to this chemical order, the partial structure factors cannot be consistent with the ones calcula...

  7. Relationship between Magnetic Anisotropy below Pseudogap Temperature and Short-Range Antiferromagnetic Order in High-Temperature Cuprate Superconductor

    Science.gov (United States)

    Morinari, Takao

    2018-06-01

    The central issue in high-temperature cuprate superconductors is the pseudogap state appearing below the pseudogap temperature T*, which is well above the superconducting transition temperature. In this study, we theoretically investigate the rapid increase of the magnetic anisotropy below the pseudogap temperature detected by the recent torque-magnetometry measurements on YBa2Cu3Oy [Y. Sato et al., 10.1038/nphys4205" xlink:type="simple">Nat. Phys. 13, 1074 (2017)]. Applying the spin Green's function formalism including the Dzyaloshinskii-Moriya interaction arising from the buckling of the CuO2 plane, we obtain results that are in good agreement with the experiment and find a scaling relationship. Our analysis suggests that the characteristic temperature associated with the magnetic anisotropy, which coincides with T*, is not a phase transition temperature but a crossover temperature associated with the short-range antiferromagnetic order.

  8. Short-range order in ab initio computer generated amorphous and liquid Cu–Zr alloys: A new approach

    International Nuclear Information System (INIS)

    Galván-Colín, Jonathan; Valladares, Ariel A.; Valladares, Renela M.; Valladares, Alexander

    2015-01-01

    Using ab initio molecular dynamics and a new approach based on the undermelt-quench method we generated amorphous and liquid samples of Cu x Zr 100−x (x=64, 50, 36) alloys. We characterized the topology of our resulting structures by means of the pair distribution function and the bond-angle distribution; a coordination number distribution was also calculated. Our results for both amorphous and liquids agree well with experiment. Dependence of short-range order with the concentration is reported. We found that icosahedron-like geometry plays a major role whenever the alloys are Cu-rich or Zr-rich disregarding if the samples are amorphous or liquid. The validation of these results, in turn would let us calculate other properties so far disregarded in the literature

  9. Short-range order in ab initio computer generated amorphous and liquid Cu–Zr alloys: A new approach

    Energy Technology Data Exchange (ETDEWEB)

    Galván-Colín, Jonathan, E-mail: jgcolin@ciencias.unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, México, D.F. 04510, México (Mexico); Valladares, Ariel A., E-mail: valladar@unam.mx [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, México, D.F. 04510, México (Mexico); Valladares, Renela M.; Valladares, Alexander [Facultad de Ciencias, Universidad Nacional Autónoma de México, Apartado Postal 70-542, México, D.F. 04510, México (Mexico)

    2015-10-15

    Using ab initio molecular dynamics and a new approach based on the undermelt-quench method we generated amorphous and liquid samples of Cu{sub x}Zr{sub 100−x} (x=64, 50, 36) alloys. We characterized the topology of our resulting structures by means of the pair distribution function and the bond-angle distribution; a coordination number distribution was also calculated. Our results for both amorphous and liquids agree well with experiment. Dependence of short-range order with the concentration is reported. We found that icosahedron-like geometry plays a major role whenever the alloys are Cu-rich or Zr-rich disregarding if the samples are amorphous or liquid. The validation of these results, in turn would let us calculate other properties so far disregarded in the literature.

  10. Effect of short-range ordering on the electrical conductivity and superconducting properties of Nb6C5 single crystals

    International Nuclear Information System (INIS)

    Utkina, T.G.

    1995-01-01

    Niobium carbide, NbC x , belongs to the family of so called interstital phases. Metal atoms form a face-centered cubic lattice, whose octahedral interstices are occupied by carbon atoms. The fraction (1 - x) of interstices remain vacant, and this determines the nonstoichiometry of these phases: most of them are characterized by a wide homogeneity range, 0.70 m ≅ 3308 - 3886 K). In contrast, the metalloid atoms exhibit high mobility at relatively low temperatures. For compositions close to Nb 6 C 5 (0.81 O-D ≅ 1300 K. The presence of vacancies in the carbon sublattice considerably affects the physical properties of carbides, which depend not only on total vacancy concentration but also on their distribution, i.e., on the degree of ordering (both short-range and long-range order) in the metalloid sublattice. The purpose of this work is to study the effects of such ordering on the superconducting properties of Nb 6 C 5 single crystals

  11. Correlation between short-range order, optical properties and UV-absorption ability in tellurate glasses; Poster M7

    Energy Technology Data Exchange (ETDEWEB)

    Burger, H; Tews, W; Vogel, W; Kozhukharov, V [Jena Univ. (Germany)

    1989-01-01

    Tellurate glasses, with as second components Al[sub 2]O[sub 3], PbO, PbF[sub 2], PbCl[sub 2], PbBr[sub 2], PbSO[sub 4], ZnO, B[sub 2]O[sub 3], P[sub 2]O[sub 5], Li[sub 2]O, Na[sub 2]O, K[sub 2]O, MgO and BaO as well as some glasses from ternary TeO[sub 2]-P[sub 2]O[sub 5]-RO systems (R is Pb, Ba and Zn ions), have been investigated. Transmittance spectra in UV and VIS region of some selected glasses have been measured. A correlation between optical properties and UV absorption edge of the transmittance have been done. Using p[sup 31]-NMR spectroscopy the structural changes on short-range level order are studied. A strong influence on the refraction and dispersion values as well as UV-absorption ability of the glasses is established. For p[sup 31] -NMR spectroscopy investigations of crystalline phosphotellurites and related phosphotellurite glasses the TeO[sub 2]-P[sub 2]O[sub 5B]aO ternary system have been chosen. (author).

  12. Concentration and temperature dependence of short-range order in Ni-Ta solid solution using X-ray diffraction method

    International Nuclear Information System (INIS)

    Khwaja, F.A.; Alam, A.

    1980-09-01

    Diffuse X-ray scattering investigations about the existence of short-range order (SRO) have been carried out in the Ni-Ta system for different concentrations and annealing temperatures. It is observed that the values of the SRO parameters for the first co-ordination shell have anomalously large negative values for all the samples studied. These values of the α 1 depend upon the annealing temperatures and the concentration of Ta atoms in the Ni-Ta system. The results of the theoretical predictions of the ordering potential obtained using the formulae of the electronic theory of SRO, confirm the existence of very strong attractive correlation between the atoms of the different species in this system. (author)

  13. High-energy X-ray study of short range order and phase transformations in titanium-vanadium

    International Nuclear Information System (INIS)

    Ramsteiner, I.B.

    2005-01-01

    This work presents a study of configurational correlations and phase transformations in the binary alloy Ti-V, using high-energy X-ray diffraction. The experiments have been performed at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The high-energy (60-100 keV) technique developed recently allows in-situ measurements on bulk material in transmission geometry. The first part of the thesis discusses multiple scattering effects which might occur with this method. These effects are experimentally verified and discussed. Special emphasis is put on the questions, whether they affect the results obtained with this method, and how they can be avoided. Understanding alloys on the most fundamental level requires knowledge about the atomic interaction potentials. Competing with entropy, these potentials determine the configurational short range order in a disordered alloy, which generates together with static and dynamic distortions the diffuse scattering. The thesis presents measurements and calculations of the diffuse scattering patterns of Ti-V. The calculations, taking into account configurational correlations, static distortions induced by atomic size mismatch and thermal diffuse scattering, agree with the experimental data. Structural transformations in Ti-V are carefully characterized using high-energy x-ray diffraction in combination with the complementary transmission electron microscopy (TEM). While the first technique allows to study the phenomena in-situ and time-resolved, TEM yields real space images and chemical information about the phases. Ti-V near the equiatomic composition is a beta-Ti-alloy. The body centered cubic beta phase is retained at room temperature by fast quenching. Aging the material below the phase transformation temperature, however, leads to the precipitation of hexagonal alpha titanium. Another transformation process confusing earlier works is identified as TiC formation from carbon impurities in the material. In addition

  14. Applications of the KKR-DCA: A Finite-Temperature Density Functional Theory to Predict Chemical Short-Range Order Effects in Disordered Metallic Alloys

    Science.gov (United States)

    Biava, D. A.; Johnson, D. D.

    2009-03-01

    Short-range order (SRO) is ubiquitous in metallic alloys, affecting changes in their electronic, thermodynamic, mechanical, magnetic, and structural properties. For example, SRO is responsible for the yield-strength anomalies observed in Cu-Al at high temperatures, i.e., the materials is more resistant to dislocation motion at high temperature than it is at room temperature. Within the Korringa-Kohn-Rostorker (KKR) electronic-structure method, we present results using the dynamical cluster approximations (DCA) to obtain the temperature-dependent SRO in disordered alloys. We obtain the KKR-DCA SRO energetics versus local neighbor SRO parameters and minimize it at fixed temperature to predict the SRO. We show that the calculated SRO at fixed temperature compares well with available experimental results, and then correlate the results to the electronic structure. We discuss how an accurate analytic estimate can be made for the SRO in most metals due to the dependence of the grand potential on SRO.

  15. Electronic structure of disordered alloys - I: self-consistent cluster CPA incorporating off-diagonal disorder and short-range order

    International Nuclear Information System (INIS)

    Kumar, V.; Mookerjee, A.; Srivastava, V.K.

    1980-09-01

    We have developed here a self-consistent coherent potential approximation generalized to take into account effect of clusters. Off-diagonal disorder and short-range order are taken into account. A graphical method married to the recursion technique, enables us to work on realistic three-dimensional lattices. Calculations are shown for a binary alloy on a diamond lattice. (author)

  16. Deuterium short-range order in Pd0.975Ag0.025D0.685 by diffuse neutron scattering

    DEFF Research Database (Denmark)

    Blaschko, O.; Klemencic, R.; Fratzl, P.

    1983-01-01

    By diffuse neutron scattering the D short-range order in a Pd0.975Ag0.025D0.685 crystal was investigated at 50 and 70K. The results are compared with the D ordering in the PdDx system previously investigated, and it is shown that the isointensity contours around the (1/2,1,0) point are similar...

  17. BeP2: a tetrahedral structure of type order-disorder which obeys a coordination rule for short-range order

    International Nuclear Information System (INIS)

    L'Haridon, P.; David, J.; Lang, J.; Parthe, E.

    1976-01-01

    Single-crystal studies on BeP 2 indicate that this compound possesses an OD structure. The substructure has a tetragonal unit cell with: a = 3.546 A, c = 15.01 A, Z = 4, space group: I4 1 /amd. The final R factor has a value of 0.033. The atom sites in this substructure correspond to the sites of diamond if the latter is described with a tetragonal cell, where a = (2/sup 1/2//a/sub diamond/ and c = 3a/sub diamond/. A short-range order governs the occupation of these sites with Be and P atoms. Each Be has four tetrahedral P neighbors and every P has two Be and two P neighbors. Consideration of the maxima on the diffuse streaks between the sharp reflectins of the substructure leads to an intermediate unit cell with a = 7.09 A and c = 30.02 A. Coordination considerations allow a structure proposal to be formulated for this intermediate structure which is triclinic but pseudotetragonal. The true unit cell is also pseudotetragonal with a = 7.09 A and c = N . 15.01 A, where N is a large integer

  18. Short range charge/orbital ordering in La1-xSrxMn1-zBzO3 (B Cu,Zn) manganites

    International Nuclear Information System (INIS)

    Popovic, Z V; Cantarero, A; Thijssen, W H A; Paunovic, N; Dohcevic-Mitrovic, Z; Sapina, F

    2005-01-01

    We have measured the reflectivity spectra of La 1-x Sr x Mn 1-z B z O 3 (B = Cu, Zn; 0.17 ≤ x ≤ 0.30; 0 ≤ z ≤ 0.10) manganites over wide frequency (100-4000 cm -1 ) and temperature (80-300 K) ranges. Besides the previously observed infrared active modes or mode pairs at about 160 cm -1 (external mode), 350 cm -1 (bond bending mode) and 590 cm -1 (bond stretching mode), we have clearly observed two additional phonon modes at about 645 and 720 cm -1 below the temperature T 1 (T 1 C ), which coincides with the phase transition temperature when the system transforms from ferromagnetic metallic into a ferromagnetic insulator state. This transition is related to the formation of short range charge/orbitally ordered domains. The temperature T 1 of the phase transition is dependent on the doping concentration and for optimally doped samples we have found that T 1 ∼(0.93 ± 0.02) T C . Electrical resistivity and magnetization measurements versus temperature and magnetic field support the short range charge/orbital ordering scenario

  19. Microwave absorption measurements in the complex perovskite Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3}: Detection of short-range orderly regions

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, G., E-mail: memodin@yahoo.com [Seccion de Estudios de Posgrado e Investigacion, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico); Montiel, H. [Departamento de Tecnociencias, Centro de Ciencias Aplicadas y Desarrollo Tecnologico de la Universidad Nacional Autonoma de Mexico, Apartado Postal 70-360, Mexico DF 04510 (Mexico); Castellanos, M.A. [Facultad de Quimica, Universidad Nacional Autonoma de Mexico, Cd. Universitaria, Mexico DF 04510 (Mexico); Heiras, J. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km. 107, Carretera Tijuana Ensenada, Ensenada, Baja California 22860 (Mexico); Zamorano, R. [Seccion de Estudios de Posgrado e Investigacion, ESFM-IPN, U.P. Adolfo Lopez Mateos Edificio 9, Av. Instituto Politecnico Nacional S/N, San Pedro Zacatenco, Mexico DF 07738 (Mexico)

    2011-10-17

    Highlights: {yields} LFMA spectra showed straight lines with positive slope and non-hysteretic traces. {yields} The spectral changes for the plot of the slope vs. temperature give evidence of the formation of iron clusters. {yields} These small orderly regions of iron ions generate short-range magnetic correlations, and that they produce changes in dynamics of microwave absorption. - Abstract: An electron paramagnetic resonance (EPR) study of the complex perovskite Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3} (PFT) at X-band (8.8-9.8 GHz) is presented. The EPR spectra show a single broad line in the 300-480 K temperature range, attributable to Fe{sup 3+} (S = 5/2) ions. The temperature dependence of the EPR parameters: the peak-to-peak linewidth ({Delta}H{sub pp}), the resonance field (H{sub res}) and the integrated intensity (I{sub EPR}), suggests the existence of short-range magnetic correlations; which are associated with the presence of small orderly regions of iron ions in B-sites of the perovskites-type structure, and that they give origin to formation of iron clusters. Low-field microwave absorption (LFMA) is used to give further knowledge on this material; where this technique also gives evidence of these short-range orderly regions.

  20. Growth of epitaxially oriented Ag nanoislands on air-oxidized Si(1 1 1)-(7 × 7) surfaces: Influence of short-range order on the substrate

    International Nuclear Information System (INIS)

    Roy, Anupam; Bhattacharjee, K.; Ghatak, J.; Dev, B.N.

    2012-01-01

    Clean Si(1 1 1)-(7 × 7) surfaces, followed by air-exposure, have been investigated by reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). Fourier transforms (FTs) of STM images show the presence of short-range (7 × 7) order on the air-oxidized surface. Comparison with FTs of STM images from a clean Si(1 1 1)-(7 × 7) surface shows that only the 1/7th order spots are present on the air-oxidized surface. The oxide layer is ∼2-3 nm thick, as revealed by cross-sectional transmission electron microscopy (XTEM). Growth of Ag islands on these air-oxidized Si(1 1 1)-(7 × 7) surfaces has been investigated by in situ RHEED and STM and ex situ XTEM and scanning electron microscopy. Ag deposition at room temperature leads to the growth of randomly oriented Ag islands while preferred orientation evolves when Ag is deposited at higher substrate temperatures. For deposition at 550 °C face centered cubic Ag nanoislands grow with a predominant epitaxial orientation [11 ¯ 0] Ag ||[11 ¯ 0] Si , (1 1 1) Ag || (1 1 1) Si along with its twin [1 ¯ 10] Ag ||[11 ¯ 0] Si , (1 1 1) Ag || (1 1 1) Si , as observed for epitaxial growth of Ag on Si(1 1 1) surfaces. The twins are thus rotated by a 180° rotation of the Ag unit cell about the Si[1 1 1] axis. It is intriguing that Ag nanoislands follow an epitaxial relationship with the Si(1 1 1) substrate in spite of the presence of a 2-3 nm thick oxide layer between Ag and Si. Apparently the short-range order on the oxide surface influences the crystallographic orientation of the Ag nanoislands.

  1. Structure of short-range-ordered iron(III)-precipitates formed by iron(II) oxidation in water containing phosphate, silicate, and calcium

    Science.gov (United States)

    Voegelin, A.; Frommer, J.; Vantelon, D.; Kaegi, R.; Hug, S. J.

    2009-04-01

    The oxidation of Fe(II) in water leads to the formation of Fe(III)-precipitates that strongly affect the fate of nutrients and contaminants in natural and engineered systems. Examples include the cycling of As in rice fields irrigated with As-rich groundwater or the treatment of drinking water for As removal. Knowledge of the types of Fe(III)-precipitates forming in such systems is essential for the quantitative modeling of nutrient and contaminant dynamics and for the optimization of water purification techniques on the basis of a mechanistic understanding of the relevant biogeochemical processes. In this study, we investigated the local coordination of Fe, P, and Ca in Fe(III)-precipitates formed by aeration of synthetic Fe(II)-containing groundwater with variable composition (pH 7, 2-30 mg/L Fe(II), 2-20 mg/L phosphate-P, 2-20 mg/L silicate-Si, 8 mM Na-bicarbonate or 2.5 mM Ca-&1.5 mM Mg-bicarbonate). After 4 hours of oxidation, Fe(III)-precipitates were collected on 0.2 µm nylon filters and dried. The precipitates were analyzed by Fe K-edge EXAFS (XAS beamline, ANKA, Germany) and by P and Ca K-edge XANES spectroscopy (LUCIA beamline, SLS, Switzerland). The Fe K-edge EXAFS spectra indicated that local Fe coordination in the precipitates systematically shifted with water composition. As long as water contained P, mainly short-range-ordered Fe(III)-phosphate formed (with molar P/Fe ~0.5). In the absence of P, Fe(III) precipitated as hydrous ferric oxide at high Si/Fe>0.5, as ferrihydrite at intermediate Si/Fe, and mainly as lepidocrocite at Si/Fe<0.2. Analysis of the EXAFS by shell-fitting indicated that Fe(III)-phosphates mainly contained mono- or oligomeric (edge- or corner-sharing) Fe and that the linkage between neighboring Fe(III)-octahedra changed from predominantly edge-sharing in Si-rich hydrous ferric oxide to edge- and corner-sharing in ferrihydrite. Electron microscopic data showed that changes in local precipitate structure were systematically

  2. Short-range fundamental forces

    International Nuclear Information System (INIS)

    Antoniadis, I.; Baessler, S.; Buchner, M.; Fedorov, V.V.; Hoedl, S.; Nesvizhevsky, V.V.; Pignol, G.; Protasov, K.V.; Lambrecht, A.; Reynaud, S.; Sobolev, Y.

    2010-01-01

    We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: 1) spin-independent forces; 2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments

  3. Effects of short-range order on electronic properties of Zr-Ni glasses as seen from low-temperature specific heat

    International Nuclear Information System (INIS)

    Kroeger, D.M.; Koch, C.C.; Scarbrough, J.O.; McKamey, C.G.

    1984-01-01

    Measurements of the low-temperature specific heat C/sub p/ of liquid-quenched Zr-Ni glasses for a large number of compositions in the range from 55 to 74 at. % Zr revealed an unusual composition dependence of the density of states at the Fermi level, N(E/sub F/). Furthermore, for some compositions the variation of C/sub p/ near the superconducting transition temperature T/sub c/ indicated the presence of two superconducting phases, i.e., two superconducting transitions were detected. Comparison of the individual T/sub c/'s in phase-separated samples to the composition dependence of T/sub c/ for all of the samples suggests that amorphous phases with compositions near 60 and 66.7 at. % Zr occur. We discuss these results in terms of an ''association model'' for liquid alloys (due to Sommer), in which associations of unlike atoms with definite stoichiometries are assumed to exist in equilibrium with unassociated atoms. We conclude that in the composition range studied, associate clusters with the compositions Zr 3 Ni 2 and Zr 2 Ni occur. In only a few cases are the clusters sufficiently large, compared with the superconducting coherence length, for separate superconducting transitions to be observed. The variation of N(E/sub F/) with composition is discussed, as well as the effects of this chemical short-range ordering on the crystallization behavior and glass-forming tendency

  4. Effects of short-range order on electronic properties of Zr-Ni glasses as seen from low-temperature specific heat

    Science.gov (United States)

    Kroeger, D. M.; Koch, C. C.; Scarbrough, J. O.; McKamey, C. G.

    1984-02-01

    Measurements of the low-temperature specific heat Cp of liquid-quenched Zr-Ni glasses for a large number of compositions in the range from 55 to 74 at.% Zr revealed an unusual composition dependence of the density of states at the Fermi level, N(EF). Furthermore, for some compositions the variation of Cp near the superconducting transition temperature Tc indicated the presence of two superconducting phases, i.e., two superconducting transitions were detected. Comparison of the individual Tc's in phase-separated samples to the composition dependence of Tc for all of the samples suggests that amorphous phases with compositions near 60 and 66.7 at.% Zr occur. We discuss these results in terms of an "association model" for liquid alloys (due to Sommer), in which associations of unlike atoms with definite stoichiometries are assumed to exist in equilibrium with unassociated atoms. We conclude that in the composition range studied, associate clusters with the compositions Zr3Ni2 and Zr2Ni occur. In only a few cases are the clusters sufficiently large, compared with the superconducting coherence length, for separate superconducting transitions to be observed. The variation of N(EF) with composition is discussed, as well as the effects of this chemical short-range ordering on the crystallization behavior and glass-forming tendency.

  5. Ab initio molecular dynamics model for density, elastic properties and short range order of Co-Fe-Ta-B metallic glass thin films

    International Nuclear Information System (INIS)

    Hostert, C; Music, D; Schneider, J M; Bednarcik, J; Keckes, J; Kapaklis, V; Hjörvarsson, B

    2011-01-01

    Density, elastic modulus and the pair distribution function of Co-Fe-Ta-B metallic glasses were obtained by ab initio molecular dynamics simulations and measured for sputtered thin films using x-ray reflectivity, nanoindentation and x-ray diffraction using high energy photons. The computationally obtained density of 8.19 g cm -3 for Co 43 Fe 20 Ta 5.5 B 31.5 and 8.42 g cm -3 for Co 45.5 Fe 24 Ta 6 B 24.5 , as well as the Young’s moduli of 273 and 251 GPa, respectively, are consistent with our experiments and literature data. These data, together with the good agreement between the theoretical and the experimental pair distribution functions, indicate that the model established here is useful to describe the density, elasticity and short range order of Co-Fe-Ta-B metallic glass thin films. Irrespective of the investigated variation in chemical composition, (Co, Fe)-B cluster formation and Co-Fe interactions are identified by density-of-states analysis. Strong bonds within the structural units and between the metallic species may give rise to the comparatively large stiffness. (paper)

  6. First-principles theory of short-range order in size-mismatched metal alloys: Cu-Au, Cu-Ag, and Ni-Au

    International Nuclear Information System (INIS)

    Wolverton, C.; Ozolins, V.; Zunger, A.

    1998-01-01

    We describe a first-principles technique for calculating the short-range order (SRO) in disordered alloys, even in the presence of large anharmonic atomic relaxations. The technique is applied to several alloys possessing large size mismatch: Cu-Au, Cu-Ag, Ni-Au, and Cu-Pd. We find the following: (i) The calculated SRO in Cu-Au alloys peaks at (or near) the left-angle 100 right-angle point for all compositions studied, in agreement with diffuse scattering measurements. (ii) A fourfold splitting of the X-point SRO exists in both Cu 0.75 Au 0.25 and Cu 0.70 Pd 0.30 , although qualitative differences in the calculated energetics for these two alloys demonstrate that the splitting in Cu 0.70 Pd 0.30 may be accounted for by T=0 K energetics while T≠0 K configurational entropy is necessary to account for the splitting in Cu 0.75 Au 0.25 . Cu 0.75 Au 0.25 shows a significant temperature dependence of the splitting, in agreement with recent in situ measurements, while the splitting in Cu 0.70 Pd 0.30 is predicted to have a much smaller temperature dependence. (iii) Although no measurements exist, the SRO of Cu-Ag alloys is predicted to be of clustering type with peaks at the left-angle 000 right-angle point. Streaking of the SRO peaks in the left-angle 100 right-angle and left-angle 1 (1) /(2) 0 right-angle directions for Ag- and Cu-rich compositions, respectively, is correlated with the elastically soft directions for these compositions. (iv) Even though Ni-Au phase separates at low temperatures, the calculated SRO pattern in Ni 0.4 Au 0.6 , like the measured data, shows a peak along the left-angle ζ00 right-angle direction, away from the typical clustering-type left-angle 000 right-angle point. (v) The explicit effect of atomic relaxation on SRO is investigated and it is found that atomic relaxation can produce significant qualitative changes in the SRO pattern, changing the pattern from ordering to clustering type, as in the case of Cu-Ag. copyright 1998 The American

  7. Narrow resonances and short-range interactions

    International Nuclear Information System (INIS)

    Gelman, Boris A.

    2009-01-01

    Narrow resonances in systems with short-range interactions are discussed in an effective field theory (EFT) framework. An effective Lagrangian is formulated in the form of a combined expansion in powers of a momentum Q 0 | 0 --a resonance peak energy. At leading order in the combined expansion, a two-body scattering amplitude is the sum of a smooth background term of order Q 0 and a Breit-Wigner term of order Q 2 (δε) -1 which becomes dominant for δε 3 . Such an EFT is applicable to systems in which short-distance dynamics generates a low-lying quasistationary state. The EFT is generalized to describe a narrow low-lying resonance in a system of charged particles. It is shown that in the case of Coulomb repulsion, a two-body scattering amplitude at leading order in a combined expansion is the sum of a Coulomb-modified background term and a Breit-Wigner amplitude with parameters renormalized by Coulomb interactions.

  8. Short-range communication system

    Science.gov (United States)

    Alhorn, Dean C. (Inventor); Howard, David E. (Inventor); Smith, Dennis A. (Inventor)

    2012-01-01

    A short-range communication system includes an antenna, a transmitter, and a receiver. The antenna is an electrical conductor formed as a planar coil with rings thereof being uniformly spaced. The transmitter is spaced apart from the plane of the coil by a gap. An amplitude-modulated and asynchronous signal indicative of a data stream of known peak amplitude is transmitted into the gap. The receiver detects the coil's resonance and decodes same to recover the data stream.

  9. Discovery of a new phase with magnetic short range correlations and its possible relevance for the hidden order in URu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sykora, Steffen [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Becker, Klaus W. [Technische Universitaet Dresden, D-01062 Dresden (Germany)

    2016-07-01

    In this paper we discuss a new phase of the Kondo lattice model which arises from the competition of Kondo and RKKY energy scales. Normally the Kondo lattice model is used to capture the low-energy physics of heavy fermion systems. However, according to the so-called Doniach picture the Kondo state will be replaced by an antiferromagnetic state for the case that the Kondo energy scale becomes smaller than the magnetic interaction between magnetic ions. In the present study we start instead from a modified electronic one-particle dispersion which avoids nesting of particle-hole excitations. Thus the magnetic ordered state should be suppressed which provides an opportunity for the inset of a new low-energy state with competing Kondo and magnetic energies. As will be shown, this new state avoids magnetic symmetry breaking but leads to a number of physical properties which are relevant for the understanding of the hidden order state in URu{sub 2}Si{sub 2}.

  10. Exchange integrals and magnetic short range order in the system CdCr2-xGaxSe4 (0=

    International Nuclear Information System (INIS)

    Bakrim, H.; Bouslykhane, K.; Hamedoun, M.; Hourmatallah, A.; Benzakour, N.

    2005-01-01

    High-temperature series expansions are derived for the magnetic susceptibility and two-spin correlation functions for a Heisenberg ferromagnetic model on the B-spinel lattice. The calculations are developed in the framework of the random phase approximation and are given for both nearest and next-nearest neighbour exchange integrals J1 and J2, respectively. Our results are given up to order 6 in β=(kBT)-1 and are used to study the paramagnetic region of the ferromagnetic spinel CdCr 2-x Ga x Se 4 . The critical temperature Tc and the critical exponents γ and ν associated with the magnetic susceptibility χ(T) and the correlation length ξ(T), respectively are deduced by applying the Pade approximate methods. The results as a function of the dilution x obtained by the present approach are found to be in agreement with the experimental ones

  11. Short-range order in irradiated diamonds

    International Nuclear Information System (INIS)

    Agafonov, S.S.; Glazkov, V.P.; Nikolaenko, V.A.; Somenkov, V.A.

    2005-01-01

    Structural changes in irradiated diamond with a change in its density were studied. Natural diamond powders with average particle size from 14-20 μm to 0.5 mm, irradiated in beryllium block of the MR reactor up to a fluence of 1.51 x 10 21 were used as samples. Using the neutron-diffraction method, it has been established that, when density in irradiated diamonds varies, a transition from a diamond-like amorphous structure to a graphite-like structure occurs. The transition occurs at a density ρ ∼ 2.7-2.9 g/cm 3 and is accompanied by a sharp change in resistivity [ru

  12. Short range order in amorphous polycondensates

    Energy Technology Data Exchange (ETDEWEB)

    Lamers, C.; Richter, D.; Schweika, W. [Forschungszentrum Juelich GmbH (Germany). Inst. fuer Festkoerperforschung; Batoulis, J.; Sommer, K. [Bayer AG, Leverkusen (Germany); Cable, J.W. [Oak Ridge National Lab., TN (United States); Shapiro, S.M. [Brookhaven National Lab., Upton, NY (United States)

    1992-12-01

    The static coherent structure factors S(Q) of the polymer glass Bisphenol-A-Polycarbonate and its chemical variation Bisphenol-A- Polyctherkctone- both in differently deuterated versions- have been measured by spin polarized neutron scattering. The method of spin polarization analysis provided an experimental separation of coherent and incoherent scattering and a reliable intensity calibration. Results are compared to structure factors calculated for model structures which were obtained by ``amorphous cell`` computer simulations. In general reasonable agreement is found between experiment and simulation; however, certain discrepancies hint at an insufficient structural relaxation in the amorphous cell method. 15 refs, 1 fig, 1 tab.

  13. Short range order of selenite glasses

    Czech Academy of Sciences Publication Activity Database

    Neov, Dimitar; Gerasimova, I.; Yordanov, S.; Lakov, L.; Mikula, Pavol; Lukáš, Petr; Dimitriev, Y.

    1999-01-01

    Roč. 40, č. 2 (1999), s. 111-112 ISSN 0031-9090 R&D Projects: GA ČR GV202/97/K038; GA AV ČR KSK1048601 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.822, year: 1999

  14. Short range charge/orbital ordering in La{sub 1-x}Sr{sub x}Mn{sub 1-z}B{sub z}O{sub 3} (B Cu,Zn) manganites

    Energy Technology Data Exchange (ETDEWEB)

    Popovic, Z V [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Cantarero, A [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Thijssen, W H A [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Paunovic, N [Centre for Solid State Physics and New Materials, Institute of Physics, PO Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Dohcevic-Mitrovic, Z [Centre for Solid State Physics and New Materials, Institute of Physics, PO Box 68, 11080 Belgrade/Zemun (Serbia and Montenegro); Sapina, F [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain)

    2005-01-19

    We have measured the reflectivity spectra of La{sub 1-x}Sr{sub x}Mn{sub 1-z}B{sub z}O{sub 3} (B = Cu, Zn; 0.17 {<=} x {<=} 0.30; 0 {<=} z {<=} 0.10) manganites over wide frequency (100-4000 cm{sup -1}) and temperature (80-300 K) ranges. Besides the previously observed infrared active modes or mode pairs at about 160 cm{sup -1} (external mode), 350 cm{sup -1} (bond bending mode) and 590 cm{sup -1} (bond stretching mode), we have clearly observed two additional phonon modes at about 645 and 720 cm{sup -1} below the temperature T{sub 1} (T{sub 1}short range charge/orbitally ordered domains. The temperature T{sub 1} of the phase transition is dependent on the doping concentration and for optimally doped samples we have found that T{sub 1} {approx}(0.93 {+-} 0.02) T{sub C}. Electrical resistivity and magnetization measurements versus temperature and magnetic field support the short range charge/orbital ordering scenario.

  15. Electron diffraction study of the sillenites Bi12SiO20, Bi25FeO39 and Bi25InO39: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

    Directory of Open Access Journals (Sweden)

    Craig A. Scurti

    2014-08-01

    Full Text Available We present an electron diffraction study of three sillenites, Bi12SiO20, Bi25FeO39, and Bi25InO39 synthesized using the solid-state method. We explore a hypothesis, inspired by optical studies in the literature, that suggests that trivalent sillenites have additional disorder not present in the tetravalent compounds. Electron diffraction patterns of Bi25FeO39 and Bi25InO39 show streaks that confirm deviations from the ideal sillenite structure. Multi-slice simulations of electron-diffraction patterns are presented for different perturbations to the sillenite structure - partial substitution of the M site by Bi3+, random and ordered oxygen-vacancies, and a frozen-phonon model. Although comparison of experimental data to simulations cannot be conclusive, we consider the streaks as evidence of short-range ordered oxygen-vacancies.

  16. Nonlocality and short-range wetting phenomena.

    Science.gov (United States)

    Parry, A O; Romero-Enrique, J M; Lazarides, A

    2004-08-20

    We propose a nonlocal interfacial model for 3D short-range wetting at planar and nonplanar walls. The model is characterized by a binding-potential functional depending only on the bulk Ornstein-Zernike correlation function, which arises from different classes of tubelike fluctuations that connect the interface and the substrate. The theory provides a physical explanation for the origin of the effective position-dependent stiffness and binding potential in approximate local theories and also obeys the necessary classical wedge covariance relationship between wetting and wedge filling. Renormalization group and computer simulation studies reveal the strong nonperturbative influence of nonlocality at critical wetting, throwing light on long-standing theoretical problems regarding the order of the phase transition.

  17. Nonlocality and Short-Range Wetting Phenomena

    Science.gov (United States)

    Parry, A. O.; Romero-Enrique, J. M.; Lazarides, A.

    2004-08-01

    We propose a nonlocal interfacial model for 3D short-range wetting at planar and nonplanar walls. The model is characterized by a binding-potential functional depending only on the bulk Ornstein-Zernike correlation function, which arises from different classes of tubelike fluctuations that connect the interface and the substrate. The theory provides a physical explanation for the origin of the effective position-dependent stiffness and binding potential in approximate local theories and also obeys the necessary classical wedge covariance relationship between wetting and wedge filling. Renormalization group and computer simulation studies reveal the strong nonperturbative influence of nonlocality at critical wetting, throwing light on long-standing theoretical problems regarding the order of the phase transition.

  18. Role of Short-Range Chemical Ordering in (GaN) 1–x (ZnO) x for Photodriven Oxygen Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dennis P. [Department; Neuefeind, Joerg C. [Chemical; Koczkur, Kallum M. [Department; Bish, David L. [Department; Skrabalak, Sara E. [Department

    2017-07-21

    (GaN)1–x(ZnO)x (GZNO) is capable of visible-light driven water splitting, but its bandgap at x ≤ 0.15 (>2.7 eV) results in poor visible-light absorption. Unfortunately, methods to narrow its bandgap by incorporating higher ZnO concentrations are accompanied by extensive Urbach tailing near the absorption-edge, which is indicative of structural disorder or chemical inhomogeneities. We evaluated whether this disorder is intrinsic to the bond-length distribution in GZNO or is a result of defects introduced from the loss of Zn during nitridation. Here, the synthesis of GZNO derived from layered double hydroxide (LDH) precursors is described which minimizes Zn loss and chemical inhomogeneities and enhances visible-light absorption. The average and local atomic structures of LDH-derived GZNO were investigated using X-ray and neutron scattering and are correlated with their oxygen evolution rates. An isotope-contrasted neutron-scattering experiment was conducted in conjunction with reverse Monte Carlo (RMC) simulations. We showed that a bond-valence bias in the RMC refinements reproduces the short-range ordering (SRO) observed in structure refinements using isotope-contrasted neutron data. The findings suggest that positional disorder of cation–anion pairs in GZNO partially arises from SRO and influences local bond relaxations. Furthermore, particle-based oxygen evolution reactions (OERs) in AgNO3 solution reveal that the crystallite size of GZNO correlates more than positional disorder with oxygen evolution rate. These findings illustrate the importance of examining the local structure of multinary photocatalysts to identify dominant factors in particulate-based photodriven oxygen evolution.

  19. Short-range correlations with pseudopotentials

    International Nuclear Information System (INIS)

    Osman, A.

    1976-01-01

    Short-range correlations in nuclei are considered on an unitary-model operator approach. Short-range pseudopotentials have been added to achieve healing in the correlated wave functions. With the introduction of the pseudopotentials, correlated basis wave functions are constructed. The matrix element for effective interaction in nuclei is developed. The required pseudopotentials have been calculated for the Hamda-Johnston, Yale and Reid potentials and for the nuclear nucleon-nucleon potential A calculated by us according to meson exchange between nucleons. (Osman, A.)

  20. A method of short range system analysis for nuclear utilities

    International Nuclear Information System (INIS)

    Eng, R.; Mason, E.A.; Benedict, M.

    1976-01-01

    An optimization procedure has been formulated and tested that is capable of solving for the optimal generation schedule of several nuclear power reactors in an electric power utility system, under short-range, resource-limited, conditions. The optimization procedure utilizes a new concept called the Opportunity Cost of Nuclear Power (OCNP) to optimally assign the resource-limited nuclear energy to the different weeks and hours in the short-range planning horizon. OCNP is defined as the cost of displaced energy when optimally distributed nuclear energy is marginally increased. Under resource-limited conditions, the short-range 'value' of nuclear power to a utility system is not its actual generation cost, but the cost of the next best alternative supply of energy, the OCNP. OCNP is a function of a week's system reserve capacity, the system's economic loading order, the customer demand function, and the nature of the available utility system generating units. The optimized OCNP value of the short-range planning period represents the utility's short-range energy replacement cost incurred when selling nuclear energy to a neighbouring utility. (author)

  1. A short-range ensemble prediction system for southern Africa

    CSIR Research Space (South Africa)

    Park, R

    2012-10-01

    Full Text Available system for southern Africa R PARK, WA LANDMAN AND F ENGELBRECHT CSIR, PO Box 395, Pretoria, South Africa, 0001 Email: xxxxxxxxxxxxxx@csir.co.za ? www.csir.co.za INTRODUCTION This research has been conducted in order to develop a short-range ensemble... stream_source_info Park_2012.pdf.txt stream_content_type text/plain stream_size 7211 Content-Encoding ISO-8859-1 stream_name Park_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 A short-range ensemble prediction...

  2. Brownian motion in short range random potentials

    International Nuclear Information System (INIS)

    Romero, A.H.; Romero, A.H.; Sancho, J.M.

    1998-01-01

    A numerical study of Brownian motion of noninteracting particles in random potentials is presented. The dynamics are modeled by Langevin equations in the high friction limit. The random potentials are Gaussian distributed and short ranged. The simulations are performed in one and two dimensions. Different dynamical regimes are found and explained. Effective subdiffusive exponents are obtained and commented on. copyright 1998 The American Physical Society

  3. On the universality of the long-/short-range separation in multiconfigurational density-functional theory

    Science.gov (United States)

    Fromager, Emmanuel; Toulouse, Julien; Jensen, Hans Jørgen Aa.

    2007-02-01

    In many cases, the dynamic correlation can be calculated quite accurately and at a fairly low computational cost in Kohn-Sham density-functional theory (KS-DFT), using current standard approximate functionals. However, in general, KS-DFT does not treat static correlation effects (near degeneracy) adequately which, on the other hand, can be described in wave-function theory (WFT), for example, with a multiconfigurational self-consistent field (MCSCF) model. It is therefore of high interest to develop a hybrid model which combines the best of both WFT and DFT approaches. The merge of WFT and DFT can be achieved by splitting the two-electron interaction into long-range and short-range parts. The long-range part is then treated by WFT and the short-range part by DFT. In this work the authors consider the so-called "erf" long-range interaction erf(μr12)/r12, which is based on the standard error function, and where μ is a free parameter which controls the range of the long-/short-range decomposition. In order to formulate a general method, they propose a recipe for the definition of an optimal μopt parameter, which is independent of the approximate short-range functional and the approximate wave function, and they discuss its universality. Calculations on a test set consisting of He, Be, Ne, Mg, H2, N2, and H2O yield μopt≈0.4a.u.. A similar analysis on other types of test systems such as actinide compounds is currently in progress. Using the value of 0.4a.u. for μ, encouraging results are obtained with the hybrid MCSCF-DFT method for the dissociation energies of H2, N2, and H2O, with both short-range local-density approximation and PBE-type functionals.

  4. Folding of polymer chains with short-range binormal interactions

    International Nuclear Information System (INIS)

    Craig, A; Terentjev, E M

    2006-01-01

    We study the structure of chains which have anisotropic short-range contact interactions that depend on the alignment of the binormal vectors of chain segments. This represents a crude model of hydrogen bonding or 'stacking' interactions out of the plane of curvature. The polymers are treated as ribbon-like semi-flexible chains, where the plane of the ribbon is determined by the local binormal. We show that with dipole-dipole interactions between the binormals of contacting chain segments, mean-field theory predicts a first-order transition to a binormally aligned state. We describe the onset of this transition as a function of the temperature-dependent parameters that govern the chain stiffness and the strength of the binormal interaction, as well as the binormal alignment's coupling to chain collapse. We also examine a metastable state governing the folding kinetics. Finally, we discuss the possible mesoscopic structure of the aligned phase, and application of our model to secondary structure motifs like β-sheets and α-helices, as well as composite structures like β-(amyloid) fibrils

  5. Deductive multiscale simulation using order parameters

    Science.gov (United States)

    Ortoleva, Peter J.

    2017-05-16

    Illustrative embodiments of systems and methods for the deductive multiscale simulation of macromolecules are disclosed. In one illustrative embodiment, a deductive multiscale simulation method may include (i) constructing a set of order parameters that model one or more structural characteristics of a macromolecule, (ii) simulating an ensemble of atomistic configurations for the macromolecule using instantaneous values of the set of order parameters, (iii) simulating thermal-average forces and diffusivities for the ensemble of atomistic configurations, and (iv) evolving the set of order parameters via Langevin dynamics using the thermal-average forces and diffusivities.

  6. Long-range displacive to short-range order-disorder crossover in weakly concentrated KTa.sub.y./sub.Nb.sub.1-y./sub.O.sub.3./sub..

    Czech Academy of Sciences Publication Activity Database

    Trepakov, V. A.; Prosandeev, V. A.; Savinov, Maxim; Galinetto, P.; Samoggia, G.; Kapphan, S.; Jastrabík, Lubomír; Boatner, L. A.

    2002-01-01

    Roč. 41, 11B (2002), s. 7176-7178 ISSN 0021-4922 R&D Projects: GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010914 Keywords : incipient ferroelectrics * impurity effects * multiscale ordering Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.280, year: 2002

  7. Short-range correlations in quark and nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    Froemel, Frank

    2007-06-15

    In the first part of this thesis, the role of short-range correlations in quark matter is explored within the framework of the Nambu-Jona-Lasinio model. Starting from a next-to-leading order expansion in the inverse number of the quark colors, a fully self-consistent model constructed that employs the close relations between spectral functions and self-energies. In contrast to the usual quasiparticle approximations, this approach allows the investigation of the collisional broadening of the quark spectral function. Numerical calculations at various chemical potentials and zero temperature show that the short-range correlations do not only induce a finite width of the spectral function but also have some influence on the structure of the chiral phase transition. In the second part of this thesis, the temperature and density dependence of the nucleon spectral function in symmetric nuclear matter is investigated. The short-range correlations can be well described by a simple, self-consistent model on the one-particle-two-hole and two-particle-one-hole level (1p2h, 2p1h). The thermodynamically consistent description of the mean-field properties of the nucleons is ensured by incorporating a Skyrme-type potential. Calculations at temperatures and densities that can also be found in heavy-ion collisions or supernova explosions and the formation of neutron stars show that the correlations saturate at high temperatures and densities. (orig.)

  8. Order parameters in smectic liquid crystals

    International Nuclear Information System (INIS)

    Beldon, Stephen M.

    2001-01-01

    This thesis explores some of the important mechanisms for switching in smectic liquid crystals. It is mainly concerned with the interaction of the electric field and various order parameters in smectic phases. Distortion of these order parameters and also the layer structures associated with smectics are discussed in depth. Initial work is concentrated on the electroclinic effect of commercially available FLC mixtures, where experimental results suggest the presence of non-uniformity in the molecular director profile. Two possible models are suggested assuming a variation of the order parameter θ through the cell. The first model assumes that the smectic layers remain bookshelf-like, and the second that the layers tilt in a vertical chevron structure when a cone angle is induced electroclinically or otherwise. The latter model is the first 'order parameter' model of an electric field induced vertical chevron. The presence of non-uniformity in the director profile is sensed by a method similar to wavelength extinction spectroscopy. Investigations are undertaken on racemic smectic materials with high dielectric biaxiality. Modelling of such a material reveals a new electroclinic effect which shows a discrete second order phase transition on application of a field. It is suggested that a bistable electroclinic effect stabilised with a high frequency ac field may be realised if a residual polarisation is present in the high biaxiality material, and that this might be useful in the displays industry. Experimental investigations of such a material confirm the above effects close to the smectic A-C transition. Finally a higher order smectic phase, the smectic I* phase, is considered. The distortion of the hexagonal bond orientational order is investigated experimentally during application of an electric field. The first dynamic model of the switching process is presented, showing good agreement with the experimental results. It is suggested that the bond orientational

  9. A continuum order parameter for deconfinement

    International Nuclear Information System (INIS)

    Roberts, C.D.

    1997-01-01

    Dyson-Schwinger equations are presented as a non-perturbative tool for the study and modeling of QCD at finite-T. An order parameter for deconfinement, applicable for both light and heavy quarks, is introduced. In a simple Dyson-Schwinger equation model of two-flavor QCD, coincident, 2nd-order chiral symmetry restoration and deconfinement transitions occur at T ∼ 150 MeV, with the same critical exponent, Β ∼ 0.33

  10. The Order Parameter in a Spin Glass

    NARCIS (Netherlands)

    Enter, A.C.D. van; Griffiths, Robert B.

    1983-01-01

    Various possible precise definitions of an Edwards-Anderson type of order parameter for an Ising model spin glass are considered, using boundary conditions for a finite system, states of an infinite system, and a duplicate-system approach. Several of these definitions are shown to yield identical

  11. Dynamical arrest in dense short-ranged attractive colloids

    International Nuclear Information System (INIS)

    Foffi, G; Sciortino, F; Zaccarelli, E; Tartaglia, P

    2004-01-01

    We study thermodynamic and dynamic properties of model colloidal systems interacting with a hard core repulsion and a short-range attraction, and provide an overall picture of their phase diagrams which shows a very rich phenomenology. We focus on the slow dynamic properties of this model, investigating in detail the glass transition lines (both repulsive and attractive), the glass-glass transitions and the location of the higher order singularities. We discuss the relative location of the glass lines and of the metastable liquid-gas binodal, an issue relevant for the understanding of low density arrested states of matter

  12. Short range ordering and microstructure property relationship in amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shariq, A.

    2006-07-01

    A novel algorithm, ''Next Neighbourhood Evaluation (NNE)'', is enunciated during the course of this work, to elucidate the next neighbourhood atomic vicinity from the data, analysed using tomographic atom probe (TAP) that allows specifying atom positions and chemical identities of the next neighbouring atoms for multicomponent amorphous materials in real space. The NNE of the Pd{sub 55}Cu{sub 23}P{sub 22} bulk amorphous alloy reveals that the Pd atoms have the highest probability to be the next neighbours to each other. Moreover, P-P correlation corroborates earlier investigations with scattering techniques that P is not a direct next neighbour to another P atom. Analogous investigations on the Fe{sub 40}Ni{sub 40}B{sub 20} metallic glass ribbons, in the as quenched state and for a state heat treated at 350 C for 1 hour insinuate a pronounced elemental inhomogeneity for the annealed state, though, it also depicts glimpse of a slight inhomogeneity for B distribution even for the as quenched sample. Moreover, a comprehensive microstructural investigation has been carried out on the Zr{sub 53}Co{sub 23.5}Al{sub 23.5} glassy system. TEM and TAP investigations evince that the as cast bulk samples constitutes a composite structure of an amorphous phase and crystalline phase(s). The crystallization is essentially triggered at the mould walls due to heterogeneous nucleation. The three dimensional atomic reconstruction maps of the volume analysed by TAP reveal a complex stereological interconnected network of two phases. The phase that is rich in Zr and Al concentration is depleted in Co concentration while the phase that is rich in Co concentration is depleted both in Zr and Al. Zr{sub 53}Co{sub 23.5}Al{sub 23.5} glassy splat samples exhibit a single exothermic crystallization peak contrary to the as cast bulk sample with a different T{sub g} temperature. A single homogeneous amorphous phase revealed by TEM investigations depicts that the faster cooling rate during splat quenching is sufficient for the vitrification of this alloy system. Zr{sub 53}Co{sub 23.5}Al{sub 23.5} bulk samples and splat samples, both exhibit very soft ferromagnetic properties. The heat treatment of as cast bulk sample results in an increase in net magnetization. The crystallization kinetics during the heat treatment, effects both the remanent magnetization, M{sub r} and coercivity, H{sub c} accordingly. Intriguingly, a salient increase in soft ferromagnetic properties is recorded for the heat treated splat samples. (orig.)

  13. Short-range order of germanium selenide glass

    Indian Academy of Sciences (India)

    Carlo (RMC) simulations are useful to compute the partial pair distribution ... recent times,13 the sorption ability of Ge20Se80 thin films, ... and the structural configuration is adjusted so as to mini- ... it is accepted with probability exp(−(χ2 n − χ2.

  14. Level shifts induced by a short-range potential

    International Nuclear Information System (INIS)

    Karnakov, B.M.; Mur, V.D.

    1984-01-01

    Formulas are derived which express the shifts of levels with energies Esub(n)sup((0)) << rsub(c)sup(-2) in a field Vsub(f)(r) induced by a short-range potential U(r) of radius rsub(c) in terms of the low energy scattering parameters (scattering length and effective radius) with a moment l in the potential. If the interaction between the particle and center is nonresonant, the method developed is identical to perturbation theory on the scattering length. The theory is extended to systems with random degeneracy (Vsub(f) is the Coulomb potential). Formulas describing quasi-intersection of terms are obtained for the case of resonance interaction with the center in a partial wave with l not equal to 0 when energetically close levels are present in both U and Vsub(f). Some features of the level shift are mentioned for the case when the level possesses an anomalously small coupling energy and its coresponding wave function becomes delocalized with decrease of the coupling energy to zero. The problem is discussed of the level shift when the potential Vsub(f) is a potential well surrounded by a weaklyt penetrable barrier. Some applications of the theory to a particle in the field of two short-range potentials or in the field of a short-range and Coulomb centers are considered. Formulas are also obtained for the shifts and widths of the Landau levels and of the shallow level with an arbitrary moment which perturbs the Landau levels

  15. Numerical challenges of short range wake field calculations

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Thomas; Gjonaj, Erion; Weiland, Thomas [Technische Universitaet Darmstadt (Germany). Institut fuer Theorie Elektromagnetischer Felder (TEMF)

    2011-07-01

    For present and future accelerator projects with ultra short bunches the accurate and reliable calculation of short range wake fields is an important issue. However, the numerical calculation of short range wake fields is a numerical challenging task. The presentation gives an overview over the numerical challenges and techniques for short range wake field calculations. Finally, some simulation results obtained by the program PBCI developed at the TU Darmstadt are presented.

  16. Isobar configurations in nuclei and short range correlations

    CERN Document Server

    Weber, H J

    1979-01-01

    Recent results on short range correlations and isobar configurations are reviewed, and in particular a unitary version of the isobar model, coupling constants and rho -meson transition potentials, a comparison with experiments, the CERN N*-knockout from /sup 4/He, QCD and the NN interaction of short range. (42 refs).

  17. New universality class for superconducting order parameter

    International Nuclear Information System (INIS)

    Dobroliubov, M.I.; Khlebnikov, S.Yu.

    1991-04-01

    We present a model of superconductivity with pairing due to Aharonov-Bohm forces. The gap is proportional to the first power of the small parameter (in which the self-consistent perturbation scheme is developed), as opposed to the BCS class of models where the gap is exponentially suppressed with the small parameter. (orig.)

  18. Impact of additional surface observation network on short range ...

    Indian Academy of Sciences (India)

    Stations (AWS) surface observations (temperature and moisture) on the short range forecast over the Indian ... models, which are able to resolve mesoscale fea- ... J. Earth Syst. Sci. ..... terization of the snow field in a cloud model; J. Climate.

  19. Electron diffraction study of the sillenites Bi{sub 12}SiO{sub 20}, Bi{sub 25}FeO{sub 39} and Bi{sub 25}InO{sub 39}: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

    Energy Technology Data Exchange (ETDEWEB)

    Scurti, Craig A.; Arenas, D. J. [Department of Physics, University of North Florida, Jacksonville, FL 32224 (United States); Auvray, Nicolas [Department of Physics, University of North Florida, Jacksonville, FL 32224 (United States); Laboratoire de Nanotechnologie et d’Instrumentation Optique - UMR CNRS 6279, Université Technologie de Troyes, 12 rue Marie Curie, Troyes 10010 (France); Lufaso, Michael W. [Department of Chemistry, University of North Florida, Jacksonville, FL 32224 (United States); Takeda, Seiji [The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kohno, Hideo [School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502 Japan (Japan)

    2014-08-15

    We present an electron diffraction study of three sillenites, Bi{sub 12}SiO{sub 20}, Bi{sub 25}FeO{sub 39}, and Bi{sub 25}InO{sub 39} synthesized using the solid-state method. We explore a hypothesis, inspired by optical studies in the literature, that suggests that trivalent sillenites have additional disorder not present in the tetravalent compounds. Electron diffraction patterns of Bi{sub 25}FeO{sub 39} and Bi{sub 25}InO{sub 39} show streaks that confirm deviations from the ideal sillenite structure. Multi-slice simulations of electron-diffraction patterns are presented for different perturbations to the sillenite structure - partial substitution of the M site by Bi{sup 3+}, random and ordered oxygen-vacancies, and a frozen-phonon model. Although comparison of experimental data to simulations cannot be conclusive, we consider the streaks as evidence of short-range ordered oxygen-vacancies.

  20. Hard probes of short-range nucleon-nucleon correlations

    Energy Technology Data Exchange (ETDEWEB)

    J. Arrington, D. W. Higinbotham, G. Rosner, M. Sargsian

    2012-10-01

    The strong interaction of nucleons at short distances leads to a high-momentum component to the nuclear wave function, associated with short-range correlations between nucleons. These short-range, high-momentum structures in nuclei are one of the least well understood aspects of nuclear matter, relating to strength outside of the typical mean-field approaches to calculating the structure of nuclei. While it is difficult to study these short-range components, significant progress has been made over the last decade in determining how to cleanly isolate short-range correlations in nuclei. We have moved from asking if such structures exist, to mapping out their strength in nuclei and studying their microscopic structure. A combination of several different measurements, made possible by high-luminosity and high-energy accelerators, coupled with an improved understanding of the reaction mechanism issues involved in studying these structures, has led to significant progress, and provided significant new information on the nature of these small, highly-excited structures in nuclei. We review the general issues related to short-range correlations, survey recent experiments aimed at probing these short-range structures, and lay out future possibilities to further these studies.

  1. The MOLDY short-range molecular dynamics package

    Science.gov (United States)

    Ackland, G. J.; D'Mellow, K.; Daraszewicz, S. L.; Hepburn, D. J.; Uhrin, M.; Stratford, K.

    2011-12-01

    We describe a parallelised version of the MOLDY molecular dynamics program. This Fortran code is aimed at systems which may be described by short-range potentials and specifically those which may be addressed with the embedded atom method. This includes a wide range of transition metals and alloys. MOLDY provides a range of options in terms of the molecular dynamics ensemble used and the boundary conditions which may be applied. A number of standard potentials are provided, and the modular structure of the code allows new potentials to be added easily. The code is parallelised using OpenMP and can therefore be run on shared memory systems, including modern multicore processors. Particular attention is paid to the updates required in the main force loop, where synchronisation is often required in OpenMP implementations of molecular dynamics. We examine the performance of the parallel code in detail and give some examples of applications to realistic problems, including the dynamic compression of copper and carbon migration in an iron-carbon alloy. Program summaryProgram title: MOLDY Catalogue identifier: AEJU_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJU_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License version 2 No. of lines in distributed program, including test data, etc.: 382 881 No. of bytes in distributed program, including test data, etc.: 6 705 242 Distribution format: tar.gz Programming language: Fortran 95/OpenMP Computer: Any Operating system: Any Has the code been vectorised or parallelized?: Yes. OpenMP is required for parallel execution RAM: 100 MB or more Classification: 7.7 Nature of problem: Moldy addresses the problem of many atoms (of order 10 6) interacting via a classical interatomic potential on a timescale of microseconds. It is designed for problems where statistics must be gathered over a number of equivalent runs, such as

  2. Short-range components of nuclear forces: Experiment versus mythology

    International Nuclear Information System (INIS)

    Kukulin, V. I.; Platonova, M. N.

    2013-01-01

    The present-day situation around the description of various (central, spin-orbit, and tensor) components of short-range nuclear forces is discussed. A traditional picture of these interactions based on the idea of one-meson exchange is contrasted against numerous results of recent experiments. As is shown in the present study, these results often deviate strongly from the predictions of traditional models. One can therefore state that such models are inapplicable to describing short-range nuclear forces and that it is necessary to go over from a traditional description to some alternative QCD-based (or QCD-motivated) picture. This means that, despite the widespread popularity of traditional concepts of short-range nuclear forces and their applicability in many particular cases, these concepts are not more than scientific myths that show their inconsistency when analyzed from the viewpoint of the modern experiment

  3. Small Device For Short-Range Antenna Measurements Using Optics

    DEFF Research Database (Denmark)

    Yanakiev, Boyan Radkov; Nielsen, Jesper Ødum; Christensen, Morten

    2011-01-01

    This paper gives a practical solution for implementing an antenna radiation pattern measurement device using optical fibers. It is suitable for anechoic chambers as well as short range channel sounding. The device is optimized for small size and provides a cheap and easy way to make optical antenna...

  4. High-Capacity Short-Range Optical Communication Links

    DEFF Research Database (Denmark)

    Tatarczak, Anna

    Over the last decade, we have observed a tremendous spread of end-user mobile devices. The user base of a mobile application can grow or shrink by millions per day. This situation creates a pressing need for highly scalable server infrastructure; a need nowadays satisfied through cloud computing...... offered by data centers. As the popularity of cloud computing soars, the demand for high-speed, short-range data center links grows. Vertical cavity surface emitting lasers (VCSEL) and multimode fibers (MMF) prove especially well-suited for such scenarios. VCSELs have high modulation bandwidths......, we achieve 10 Gbps over 400 m and then conrm the approach in an optimized system at 25 Gbps over 300 m. The techniques described in this thesis leverage additional degrees of freedom to better utilize the available resources of short-range links. The proposed schemes enable higher speeds and longer...

  5. Schroedinger operators with point interactions and short range expansions

    International Nuclear Information System (INIS)

    Albeverio, S.; Hoeegh-Krohn, R.; Oslo Univ.

    1984-01-01

    We give a survey of recent results concerning Schroedinger operators with point interactions in R 3 . In the case where the point interactions are located at a discrete set of points we discuss results about the resolvent, the spectrum, the resonances and the scattering quantities. We also discuss the approximation of point interactions by short range local potentials (short range or low energy expansions) and the one electron model of a 3-dimensional crystal. Moreover we discuss Schroedinger operators with Coulomb plus point interactions, with applications to the determination of scattering lengths and of level shifts in mesic atoms. Further applications to the multiple well problem, to multiparticle systems, to crystals with random impurities, to polymers and quantum fields are also briefly discussed. (orig.)

  6. Thermodynamic properties of short-range square well fluid

    Science.gov (United States)

    López-Rendón, R.; Reyes, Y.; Orea, P.

    2006-08-01

    The interfacial properties of short-range square well fluid with λ =1.15, 1.25, and 1.375 were determined by using single canonical Monte Carlo simulations. Simulations were carried out in the vapor-liquid region. The coexistence curves of these models were calculated and compared to those previously reported in the literature and good agreement was found among them. We found that the surface tension curves for any potential model of short range form a single master curve when we plot γ* vs T /Tc. It is demonstrated that the critical reduced second virial coefficient B2* as a function of interaction range or Tc* is not constant.

  7. Recent results on short-range gravity experiment

    International Nuclear Information System (INIS)

    Hata, Maki; Akiyama, Takashi; Ikeda, Yuki; Kawamura, Hirokazu; Narita, Keigo; Ninomiya, Kazufumi; Ogawa, Naruya; Sato, Toshiaki; Seitaibashi, Etsuko; Sekiguchi, Yuta; Tsutsui, Ryosuke; Yazawa, Kazumasa; Murata, Jiro

    2009-01-01

    According to the ADD model, deviation from Newton's inverse square law is expected at below sub-millimeter scale. Present study is an experimental investigation of the Newton's gravitational law at a short range scale. We have developed an experimental setup using torsion balance bar, and succeeded to confirm the inverse square law at a centimeter scale. In addition, composition dependence of gravitational constant G is also tested at the centimeter scale, motivated to test the weak equivalence principle.

  8. Quantum fluctuation of the order parameter in polyacetylene

    International Nuclear Information System (INIS)

    Su Zhao-bin; Wang Ya-xin; Yu Lu.

    1984-07-01

    The effects of the lattice quantum fluctuation upon the order parameter in the Peierls systems are studied by using the Green's function technique. The order parameter is reduced but survives the quantum fluctuations in agreement with the Monte Carlo simulations. (author)

  9. Chiral-symmetry order parameter, the lattice, and nucleosynthesis

    International Nuclear Information System (INIS)

    McLerran, L.

    1987-01-01

    I discuss an order parameter for the chiral-symmetry restoration phase transition which may be useful in computations of big-bang nucleosynthesis, a phenomenon which requires a finite baryon-number density. This parameter is strictly speaking an order parameter in the large-N limit, and distinguishes between a parity-doubled and a massless-fermion realization of chiral-symmetry restoration. This order parameter may be evaluated at a zero net baryon-number density at finite temperature, and is useful as long as the baryon chemical potential μ is much less than the temperature T

  10. Short range correlations in the pion s-wave self-energy of pionic atoms

    OpenAIRE

    Salcedo, L. L.; Holinde, K.; Oset, E.; Schütz, C.

    1995-01-01

    We evaluate the contribution of second order terms to the pion-nucleus s-wave optical potential of pionic atoms generated by short range nuclear correlation. The corrections are sizeable because they involve the isoscalar s-wave $\\pi N$ amplitude for half off-shell situations where the amplitude is considerably larger than the on-shell one. In addition, the s-wave optical potential is reanalyzed by looking at all the different conventional contributions together lowest order, Pauli corrected ...

  11. The nuclear contacts and short range correlations in nuclei

    Science.gov (United States)

    Weiss, R.; Cruz-Torres, R.; Barnea, N.; Piasetzky, E.; Hen, O.

    2018-05-01

    Atomic nuclei are complex strongly interacting systems and their exact theoretical description is a long-standing challenge. An approximate description of nuclei can be achieved by separating its short and long range structure. This separation of scales stands at the heart of the nuclear shell model and effective field theories that describe the long-range structure of the nucleus using a mean-field approximation. We present here an effective description of the complementary short-range structure using contact terms and stylized two-body asymptotic wave functions. The possibility to extract the nuclear contacts from experimental data is presented. Regions in the two-body momentum distribution dominated by high-momentum, close-proximity, nucleon pairs are identified and compared to experimental data. The amount of short-range correlated (SRC) nucleon pairs is determined and compared to measurements. Non-combinatorial isospin symmetry for SRC pairs is identified. The obtained one-body momentum distributions indicate dominance of SRC pairs above the nuclear Fermi-momentum.

  12. Unsupervised learning in neural networks with short range synapses

    Science.gov (United States)

    Brunnet, L. G.; Agnes, E. J.; Mizusaki, B. E. P.; Erichsen, R., Jr.

    2013-01-01

    Different areas of the brain are involved in specific aspects of the information being processed both in learning and in memory formation. For example, the hippocampus is important in the consolidation of information from short-term memory to long-term memory, while emotional memory seems to be dealt by the amygdala. On the microscopic scale the underlying structures in these areas differ in the kind of neurons involved, in their connectivity, or in their clustering degree but, at this level, learning and memory are attributed to neuronal synapses mediated by longterm potentiation and long-term depression. In this work we explore the properties of a short range synaptic connection network, a nearest neighbor lattice composed mostly by excitatory neurons and a fraction of inhibitory ones. The mechanism of synaptic modification responsible for the emergence of memory is Spike-Timing-Dependent Plasticity (STDP), a Hebbian-like rule, where potentiation/depression is acquired when causal/non-causal spikes happen in a synapse involving two neurons. The system is intended to store and recognize memories associated to spatial external inputs presented as simple geometrical forms. The synaptic modifications are continuously applied to excitatory connections, including a homeostasis rule and STDP. In this work we explore the different scenarios under which a network with short range connections can accomplish the task of storing and recognizing simple connected patterns.

  13. Two-dimensional quasistatic stationary short range surface plasmons in flat nanoprisms.

    Science.gov (United States)

    Nelayah, J; Kociak, M; Stéphan, O; Geuquet, N; Henrard, L; García de Abajo, F J; Pastoriza-Santos, I; Liz-Marzán, L M; Colliex, C

    2010-03-10

    We report on the nanometer scale spectral imaging of surface plasmons within individual silver triangular nanoprisms by electron energy loss spectroscopy and on related discrete dipole approximation simulations. A dependence of the energy and intensity of the three detected modes as function of the edge length is clearly identified both experimentally and with simulations. We show that for experimentally available prisms (edge lengths ca. 70 to 300 nm) the energies and intensities of the different modes show a monotonic dependence as function of the aspect ratio of the prisms. For shorter or longer prisms, deviations to this behavior are identified thanks to simulations. These modes have symmetric charge distribution and result from the strong coupling of the upper and lower triangular surfaces. They also form a standing wave in the in-plane direction and are identified as quasistatic short range surface plasmons of different orders as emphasized within a continuum dielectric model. This model explains in simple terms the measured and simulated energy and intensity changes as function of geometric parameters. By providing a unified vision of surface plasmons in platelets, such a model should be useful for engineering of the optical properties of metallic nanoplatelets.

  14. Electronic structure of disordered binary alloys with short range correlation in Bethe lattice

    International Nuclear Information System (INIS)

    Moreno, I.F.

    1987-01-01

    The determination of the electronic structure of a disordered material along the tight-binding model when applied to a Bethe lattice. The diagonal as well as off-diagonal disorder, are considered. The coordination number on the Bethe is fixed lattice to four (Z=4) that occurs in most compound semiconductors. The main proposal was to study the conditions under which a relatively simple model of a disordered material, i.e, a binary alloy, could account for the basic properties of transport or more specifically for the electronic states in such systems. By using a parametrization of the pair probability the behaviour of the electronic density of states (DOS) for different values of the short range order parameter, σ, which makes possible to treat the segregated, random and alternating cases, was analysed. In solving the problem via the Green function technique in the Wannier representation a linear chain of atoms was considered and using the solution of such a 1-D system the problem of the Bethe lattice which is constructed using such renormalized chains as elements, was solved. The results indicate that the obtained DOS are strongly dependent on the correlation assumed for the occupancy in the lattice. (author) [pt

  15. Order parameter analysis of synchronization transitions on star networks

    Science.gov (United States)

    Chen, Hong-Bin; Sun, Yu-Ting; Gao, Jian; Xu, Can; Zheng, Zhi-Gang

    2017-12-01

    The collective behaviors of populations of coupled oscillators have attracted significant attention in recent years. In this paper, an order parameter approach is proposed to study the low-dimensional dynamical mechanism of collective synchronizations, by adopting the star-topology of coupled oscillators as a prototype system. The order parameter equation of star-linked phase oscillators can be obtained in terms of the Watanabe-Strogatz transformation, Ott-Antonsen ansatz, and the ensemble order parameter approach. Different solutions of the order parameter equation correspond to the diverse collective states, and different bifurcations reveal various transitions among these collective states. The properties of various transitions in the star-network model are revealed by using tools of nonlinear dynamics such as time reversibility analysis and linear stability analysis.

  16. Testing for one Generalized Linear Single Order Parameter

    DEFF Research Database (Denmark)

    Ellegaard, Niels Langager; Christensen, Tage Emil; Dyre, Jeppe

    We examine a linear single order parameter model for thermoviscoelastic relaxation in viscous liquids, allowing for a distribution of relaxation times. In this model the relaxation of volume and entalpy is completely described by the relaxation of one internal order parameter. In contrast to prior...... work the order parameter may be chosen to have a non-exponential relaxation. The model predictions contradict the general consensus of the properties of viscous liquids in two ways: (i) The model predicts that following a linear isobaric temperature step, the normalized volume and entalpy relaxation...... responses or extrapolate from measurements of a glassy state away from equilibrium. Starting from a master equation description of inherent dynamics, we calculate the complex thermodynamic response functions. We device a way of testing for the generalized single order parameter model by measuring 3 complex...

  17. Analyses of kinetic glass transition in short-range attractive colloids based on time-convolutionless mode-coupling theory.

    Science.gov (United States)

    Narumi, Takayuki; Tokuyama, Michio

    2017-03-01

    For short-range attractive colloids, the phase diagram of the kinetic glass transition is studied by time-convolutionless mode-coupling theory (TMCT). Using numerical calculations, TMCT is shown to recover all the remarkable features predicted by the mode-coupling theory for attractive colloids: the glass-liquid-glass reentrant, the glass-glass transition, and the higher-order singularities. It is also demonstrated through the comparisons with the results of molecular dynamics for the binary attractive colloids that TMCT improves the critical values of the volume fraction. In addition, a schematic model of three control parameters is investigated analytically. It is thus confirmed that TMCT can describe the glass-glass transition and higher-order singularities even in such a schematic model.

  18. Solliton-like order parameter distributions in the critical region

    Directory of Open Access Journals (Sweden)

    A.V.Babich

    2006-01-01

    Full Text Available Some exact one-component order parameter distributions for the Michelson thermodynamic potential are obtained. The phase transition of second kind in Ginzburg-Landau type model is investigated. The exact partial distribution of the order parameter in the form of Jakobi elliptic function is obtained. The energy of this distribution is lower at some temperature interval than for the best known models.

  19. Fluctuations of order parameters in the high Tc superconductors

    International Nuclear Information System (INIS)

    Das, M.P.; Saif, A.G.

    1987-07-01

    Recently we have proposed a phenomenological approach in terms of two coexisting macroscopic order parameters corresponding to the superconducting and insulating states and have discussed the electrodynamical responses of the superconducting ceramics. In this paper we discuss the fluctuations of the order parameters both in the static and in the dynamical situations in the mean field approach and obtain results for the electrical conductivity which possesses anomalies as in granular materials. (author). 22 refs

  20. Short-range disorder in pseudobinary ionic alloys

    International Nuclear Information System (INIS)

    Di Cicco, Andrea; Principi, Emiliano; Filipponi, Adriano

    2002-01-01

    The short-range distribution functions of the RbBr 1-x I x solid and molten ionic alloys have been accurately measured using multiple-edge refinement of the K-edge extended x-ray absorption fine structure spectra (EXAFS). The local structure is characterized by two well-defined first-neighbor peaks associated with the Rb-I and Rb-Br distributions, both for solid and liquid alloys. The distribution of distances in solid alloys gives experimental evidence to available theoretical models. In the liquid, the two distance distributions are found to be practically independent of the concentration x. The effect of different effective charge screening of the ions is observed in the molten systems for limiting concentrations

  1. Kernel optimization for short-range molecular dynamics

    Science.gov (United States)

    Hu, Changjun; Wang, Xianmeng; Li, Jianjiang; He, Xinfu; Li, Shigang; Feng, Yangde; Yang, Shaofeng; Bai, He

    2017-02-01

    To optimize short-range force computations in Molecular Dynamics (MD) simulations, multi-threading and SIMD optimizations are presented in this paper. With respect to multi-threading optimization, a Partition-and-Separate-Calculation (PSC) method is designed to avoid write conflicts caused by using Newton's third law. Serial bottlenecks are eliminated with no additional memory usage. The method is implemented by using the OpenMP model. Furthermore, the PSC method is employed on Intel Xeon Phi coprocessors in both native and offload models. We also evaluate the performance of the PSC method under different thread affinities on the MIC architecture. In the SIMD execution, we explain the performance influence in the PSC method, considering the "if-clause" of the cutoff radius check. The experiment results show that our PSC method is relatively more efficient compared to some traditional methods. In double precision, our 256-bit SIMD implementation is about 3 times faster than the scalar version.

  2. Freely cooling granular gases with short-ranged attractive potentials

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Eric; Subramaniam, Shankar, E-mail: shankar@iastate.edu [Department of Mechanical Engineering, Center for Multiphase Flow Research, Iowa State University, Ames, Iowa 50011 (United States)

    2015-04-15

    We treat the case of an undriven gas of inelastic hard-spheres with short-ranged attractive potentials via an extension of the pseudo-Liouville operator formalism. New evolution equations for the granular temperature and coordination number are obtained. The granular temperature exhibits deviation from both Haff’s law and the case of long-ranged potentials. We verify this departure using soft-sphere discrete element method simulations. Excellent agreement is found for the duration of the simulation even beyond where exclusively binary collisions are expected. Simulations show the emergence of strong spatial-velocity correlations on the length scale of the last peak in the pair-correlation function but do not show strong correlations beyond this length scale. We argue that molecular chaos may remain an adequate approximation if the system is modelled as a Smoluchowski type equation with aggregation and break-up processes.

  3. Local and nonlocal order parameters in the Kitaev chain

    Science.gov (United States)

    Chitov, Gennady Y.

    2018-02-01

    We have calculated order parameters for the phases of the Kitaev chain with interaction and dimerization at a special symmetric point applying the Jordan-Wigner and other duality transformations. We use string order parameters (SOPs) defined via the correlation functions of the Majorana string operators. The SOPs are mapped onto the local order parameters of some dual Hamiltonians and easily calculated. We have shown that the phase diagram of the interacting dimerized chain comprises the phases with the conventional local order as well as the phases with nonlocal SOPs. From the results for the critical indices, we infer the two-dimensional Ising universality class of criticality at the particular symmetry point where the model is exactly solvable.

  4. Examining a Thermodynamic Order Parameter of Protein Folding.

    Science.gov (United States)

    Chong, Song-Ho; Ham, Sihyun

    2018-05-08

    Dimensionality reduction with a suitable choice of order parameters or reaction coordinates is commonly used for analyzing high-dimensional time-series data generated by atomistic biomolecular simulations. So far, geometric order parameters, such as the root mean square deviation, fraction of native amino acid contacts, and collective coordinates that best characterize rare or large conformational transitions, have been prevailing in protein folding studies. Here, we show that the solvent-averaged effective energy, which is a thermodynamic quantity but unambiguously defined for individual protein conformations, serves as a good order parameter of protein folding. This is illustrated through the application to the folding-unfolding simulation trajectory of villin headpiece subdomain. We rationalize the suitability of the effective energy as an order parameter by the funneledness of the underlying protein free energy landscape. We also demonstrate that an improved conformational space discretization is achieved by incorporating the effective energy. The most distinctive feature of this thermodynamic order parameter is that it works in pointing to near-native folded structures even when the knowledge of the native structure is lacking, and the use of the effective energy will also find applications in combination with methods of protein structure prediction.

  5. Perturbation theory for short-range weakly-attractive potentials in one dimension

    Energy Technology Data Exchange (ETDEWEB)

    Amore, Paolo, E-mail: paolo.amore@gmail.com [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal Díaz del Castillo 340, Colima, Colima (Mexico); Fernández, Francisco M., E-mail: fernande@quimica.unlp.edu.ar [INIFTA (UNLP, CONICET), Division Química Teórica, Blvd. 113 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)

    2017-03-15

    We have obtained the perturbative expressions up to sixth order for the energy of the bound state in a one dimensional, arbitrarily weak, short range finite well, applying a method originally developed by Gat and Rosenstein Ref. [1]. The expressions up to fifth order reproduce the results already known in the literature, while the sixth order had not been calculated before. As an illustration of our formulas we have applied them to two exactly solvable problems and to a nontrivial problem.

  6. Combining 2-m temperature nowcasting and short range ensemble forecasting

    Directory of Open Access Journals (Sweden)

    A. Kann

    2011-12-01

    Full Text Available During recent years, numerical ensemble prediction systems have become an important tool for estimating the uncertainties of dynamical and physical processes as represented in numerical weather models. The latest generation of limited area ensemble prediction systems (LAM-EPSs allows for probabilistic forecasts at high resolution in both space and time. However, these systems still suffer from systematic deficiencies. Especially for nowcasting (0–6 h applications the ensemble spread is smaller than the actual forecast error. This paper tries to generate probabilistic short range 2-m temperature forecasts by combining a state-of-the-art nowcasting method and a limited area ensemble system, and compares the results with statistical methods. The Integrated Nowcasting Through Comprehensive Analysis (INCA system, which has been in operation at the Central Institute for Meteorology and Geodynamics (ZAMG since 2006 (Haiden et al., 2011, provides short range deterministic forecasts at high temporal (15 min–60 min and spatial (1 km resolution. An INCA Ensemble (INCA-EPS of 2-m temperature forecasts is constructed by applying a dynamical approach, a statistical approach, and a combined dynamic-statistical method. The dynamical method takes uncertainty information (i.e. ensemble variance from the operational limited area ensemble system ALADIN-LAEF (Aire Limitée Adaptation Dynamique Développement InterNational Limited Area Ensemble Forecasting which is running operationally at ZAMG (Wang et al., 2011. The purely statistical method assumes a well-calibrated spread-skill relation and applies ensemble spread according to the skill of the INCA forecast of the most recent past. The combined dynamic-statistical approach adapts the ensemble variance gained from ALADIN-LAEF with non-homogeneous Gaussian regression (NGR which yields a statistical mbox{correction} of the first and second moment (mean bias and dispersion for Gaussian distributed continuous

  7. Order parameter fluctuations and collective modes in superconductors

    International Nuclear Information System (INIS)

    Carlson, R.V.

    1975-06-01

    Measurements of the frequency and wave vector dependence of the pair-field susceptibility and the dynamical structure factor of homogeneous, short mean free path aluminum films have been carried out. These measurements critically probe the dynamical nature of order parameter fluctuations in the vicinity of the superconducting phase transition. Two important results are found. The first is that at temperatures higher than the transition temperature of the aluminum film, the fluctuations of the order parameter can be described by a diffusive time-dependent generalization of the Ginzburg-Landau equation. Detailed comparison of the data to the results of theoretical calculations of Scalapino, and Shenoy and Lee is carried out. Except in the immediate vicinity of the transition, there is excellent agreement with the theories. A major discrepancy between theory and experiment does exist in the vicinity of the superconducting transition, in that the pair relaxation frequency falls well below the theoretical predictions. Possible explanations of this behavior are discussed. Below the transition temperature measurements of the structure factor (Fourier transform of the order parameter-order parameter correlation function) provide the first clear cut demonstration of the existence of a propagating, low frequency, order parameter collective mode which appears as a finite frequency peak in the structure factor. This mode has been identified with fluctuations in the phase of the order parameter and has a linear dispersion relation over the range in which it is observed. A detailed comparison to some of the theoretical explanations is made, with the conclusion that at this time, existing theories do not adequately explain the behavior of the mode over the range of temperature and magnetic field in which it is observed. (4 figures, 4 tables, 86 references) (U.S.)

  8. Glass-forming liquids: one or more "order" parameters"

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Christensen, Tage Emil; Jakobsen, Bo

    2008-01-01

    We first summarize the classical arguments that the vast majority of glass-forming liquids require more than one ‘order' parameter for their description. Critiques against this conventional wisdom are then presented, and it is argued that the matter deserves to be reconsidered in the light...... that a description with a single "order" parameter applies to a good approximation whenever thermal equilibrium fluctuations of fundamental variables like energy and pressure are strongly correlated. Results from computer simulations showing that this is the case for a number of simple glass-forming liquids, as well...

  9. Single-order-parameter description of glass-forming liquids

    DEFF Research Database (Denmark)

    Ellegaard, Niels Langager; Christensen, Tage Emil; Christiansen, Peder Voetmann

    2007-01-01

    Thermoviscoelastic linear-response functions are calculated from the master equation describing viscous liquid inherent dynamics. From the imaginary parts of the frequency-dependent isobaric specific heat, isothermal compressibility, and isobaric thermal expansion coefficient, we define a "linear...... dynamic Prigogine-Defay ratio" with the property that if this ratio is unity at one frequency, then it is unity at all frequencies. This happens if and only if there is a single-order-parameter description of the thermoviscoelastic linear responses via an order parameter which may be nonexponential...

  10. Hybrid superconducting-magnetic memory device using competing order parameters.

    Science.gov (United States)

    Baek, Burm; Rippard, William H; Benz, Samuel P; Russek, Stephen E; Dresselhaus, Paul D

    2014-05-28

    In a hybrid superconducting-magnetic device, two order parameters compete, with one type of order suppressing the other. Recent interest in ultra-low-power, high-density cryogenic memories has spurred new efforts to simultaneously exploit superconducting and magnetic properties so as to create novel switching elements having these two competing orders. Here we describe a reconfigurable two-layer magnetic spin valve integrated within a Josephson junction. Our measurements separate the suppression in the superconducting coupling due to the exchange field in the magnetic layers, which causes depairing of the supercurrent, from the suppression due to the stray magnetic field. The exchange field suppression of the superconducting order parameter is a tunable and switchable behaviour that is also scalable to nanometer device dimensions. These devices demonstrate non-volatile, size-independent switching of Josephson coupling, in magnitude as well as phase, and they may enable practical nanoscale superconducting memory devices.

  11. Hybrid gesture recognition system for short-range use

    Science.gov (United States)

    Minagawa, Akihiro; Fan, Wei; Katsuyama, Yutaka; Takebe, Hiroaki; Ozawa, Noriaki; Hotta, Yoshinobu; Sun, Jun

    2012-03-01

    In recent years, various gesture recognition systems have been studied for use in television and video games[1]. In such systems, motion areas ranging from 1 to 3 meters deep have been evaluated[2]. However, with the burgeoning popularity of small mobile displays, gesture recognition systems capable of operating at much shorter ranges have become necessary. The problems related to such systems are exacerbated by the fact that the camera's field of view is unknown to the user during operation, which imposes several restrictions on his/her actions. To overcome the restrictions generated from such mobile camera devices, and to create a more flexible gesture recognition interface, we propose a hybrid hand gesture system, in which two types of gesture recognition modules are prepared and with which the most appropriate recognition module is selected by a dedicated switching module. The two recognition modules of this system are shape analysis using a boosting approach (detection-based approach)[3] and motion analysis using image frame differences (motion-based approach)(for example, see[4]). We evaluated this system using sample users and classified the resulting errors into three categories: errors that depend on the recognition module, errors caused by incorrect module identification, and errors resulting from user actions. In this paper, we show the results of our investigations and explain the problems related to short-range gesture recognition systems.

  12. Short-range quantitative precipitation forecasting using Deep Learning approaches

    Science.gov (United States)

    Akbari Asanjan, A.; Yang, T.; Gao, X.; Hsu, K. L.; Sorooshian, S.

    2017-12-01

    Predicting short-range quantitative precipitation is very important for flood forecasting, early flood warning and other hydrometeorological purposes. This study aims to improve the precipitation forecasting skills using a recently developed and advanced machine learning technique named Long Short-Term Memory (LSTM). The proposed LSTM learns the changing patterns of clouds from Cloud-Top Brightness Temperature (CTBT) images, retrieved from the infrared channel of Geostationary Operational Environmental Satellite (GOES), using a sophisticated and effective learning method. After learning the dynamics of clouds, the LSTM model predicts the upcoming rainy CTBT events. The proposed model is then merged with a precipitation estimation algorithm termed Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) to provide precipitation forecasts. The results of merged LSTM with PERSIANN are compared to the results of an Elman-type Recurrent Neural Network (RNN) merged with PERSIANN and Final Analysis of Global Forecast System model over the states of Oklahoma, Florida and Oregon. The performance of each model is investigated during 3 storm events each located over one of the study regions. The results indicate the outperformance of merged LSTM forecasts comparing to the numerical and statistical baselines in terms of Probability of Detection (POD), False Alarm Ratio (FAR), Critical Success Index (CSI), RMSE and correlation coefficient especially in convective systems. The proposed method shows superior capabilities in short-term forecasting over compared methods.

  13. Exploiting orbital effects for short-range extravehicular transfers

    Science.gov (United States)

    Williams, Trevor; Baughman, David

    The problem studied in this paper is that of using Simplified Aid for Extravehicular Activity (EVA) Rescue (SAFER) to carry out efficient short-range transfers from the payload bay of the Space Shuttle Orbiter to the vicinity of the underside of the vehicle, for instance for inspection and repair of thermal tiles or umbilical doors. Trajectories are shown to exist, for the shuttle flying noise forward and belly down, that take the astronaut to the vicinity of the underside with no thrusting after the initial push-off. However, these trajectories are too slow to be of practical interest, as they take roughly an hour to execute. Additionally, they are quite sensitive to errors in the initial push-off rates. To overcome both of these difficulties, trajectories are then studied which include a single in-flight impulse of small magnitude ( in the range 0.1 - 0.4 fps). For operational simplicity, this impulse is applied towards the Orbiter at the moment when the line-of -sight of the EVA crewmember is tangential to the underside of the vehicle. These trajectories are considerably faster than the non-impulsive ones: transit times of less than 10 minutes are achievable. Furthermore, the man-in-the-loop feedback scheme used for impulse timing greatly reduces the sensitivity to initial velocity errors. Finally, similar one-impulse trajectories are also shown to exist for the Orbiter in a gravity-gradient attitiude.

  14. Short range spread-spectrum radiolocation system and method

    Science.gov (United States)

    Smith, Stephen F.

    2003-04-29

    A short range radiolocation system and associated methods that allow the location of an item, such as equipment, containers, pallets, vehicles, or personnel, within a defined area. A small, battery powered, self-contained tag is provided to an item to be located. The tag includes a spread-spectrum transmitter that transmits a spread-spectrum code and identification information. A plurality of receivers positioned about the area receive signals from a transmitting tag. The position of the tag, and hence the item, is located by triangulation. The system employs three different ranging techniques for providing coarse, intermediate, and fine spatial position resolution. Coarse positioning information is provided by use of direct-sequence code phase transmitted as a spread-spectrum signal. Intermediate positioning information is provided by the use of a difference signal transmitted with the direct-sequence spread-spectrum code. Fine positioning information is provided by use of carrier phase measurements. An algorithm is employed to combine the three data sets to provide accurate location measurements.

  15. Order parameters in smectic liquid crystals[Smectics

    Energy Technology Data Exchange (ETDEWEB)

    Beldon, Stephen M

    2001-07-01

    This thesis explores some of the important mechanisms for switching in smectic liquid crystals. It is mainly concerned with the interaction of the electric field and various order parameters in smectic phases. Distortion of these order parameters and also the layer structures associated with smectics are discussed in depth. Initial work is concentrated on the electroclinic effect of commercially available FLC mixtures, where experimental results suggest the presence of non-uniformity in the molecular director profile. Two possible models are suggested assuming a variation of the order parameter {theta} through the cell. The first model assumes that the smectic layers remain bookshelf-like, and the second that the layers tilt in a vertical chevron structure when a cone angle is induced electroclinically or otherwise. The latter model is the first 'order parameter' model of an electric field induced vertical chevron. The presence of non-uniformity in the director profile is sensed by a method similar to wavelength extinction spectroscopy. Investigations are undertaken on racemic smectic materials with high dielectric biaxiality. Modelling of such a material reveals a new electroclinic effect which shows a discrete second order phase transition on application of a field. It is suggested that a bistable electroclinic effect stabilised with a high frequency ac field may be realised if a residual polarisation is present in the high biaxiality material, and that this might be useful in the displays industry. Experimental investigations of such a material confirm the above effects close to the smectic A-C transition. Finally a higher order smectic phase, the smectic I* phase, is considered. The distortion of the hexagonal bond orientational order is investigated experimentally during application of an electric field. The first dynamic model of the switching process is presented, showing good agreement with the experimental results. It is suggested that the bond

  16. First Measurements of Higher Order Optics Parameters in the LHC

    CERN Document Server

    Vanbavinckhove, G; Bartolini, R; Calaga, R; Giovannozzi, M; Maclean, E H; Miyamoto, R; Schmidt, F; Tomas, R

    2011-01-01

    Higher order effects can play an important role in the performance of the LHC. Lack of knowledge of these pa- rameters can increase the tune footprint and compromise the beam lifetime. First measurements of these parameters at injection and flattop have been conducted. Detailed sim- ulations are compared to the measurements together with discussions on the measurement limitations.

  17. Riccati-parameter solutions of nonlinear second-order ODEs

    International Nuclear Information System (INIS)

    Reyes, M A; Rosu, H C

    2008-01-01

    It has been proven by Rosu and Cornejo-Perez (Rosu and Cornejo-Perez 2005 Phys. Rev. E 71 046607, Cornejo-Perez and Rosu 2005 Prog. Theor. Phys. 114 533) that for some nonlinear second-order ODEs it is a very simple task to find one particular solution once the nonlinear equation is factorized with the use of two first-order differential operators. Here, it is shown that an interesting class of parametric solutions is easy to obtain if the proposed factorization has a particular form, which happily turns out to be the case in many problems of physical interest. The method that we exemplify with a few explicitly solved cases consists in using the general solution of the Riccati equation, which contributes with one parameter to this class of parametric solutions. For these nonlinear cases, the Riccati parameter serves as a 'growth' parameter from the trivial null solution up to the particular solution found through the factorization procedure

  18. Chiral approach to nuclear matter: Role of explicit short-range NN-terms

    International Nuclear Information System (INIS)

    Fritsch, S.; Kaiser, N.

    2004-01-01

    We extend a recent chiral approach to nuclear matter by including the most general (momentum-independent) NN-contact interaction. Iterating this two-parameter contact vertex with itself and with one-pion exchange the emerging energy per particle exhausts all terms possible up to and including fourth order in the small momentum expansion. Two (isospin-dependent) cut-offs Λ 0,1 are introduced to regularize the (linear) divergences of some three-loop in-medium diagrams. The equation of state of pure neutron matter, anti E n (k n ), can be reproduced very well up to quite high neutron densities of ρ n =0.5 fm -3 by adjusting the strength of a repulsive nn-contact interaction. Binding and saturation of isospin-symmetric nuclear matter is a generic feature of our perturbative calculation. Fixing the maximum binding energy per particle to - anti E(k f0 )=15.3 MeV we find that any possible equilibrium density ρ 0 lies below ρ 0 max =0.191 fm -3 . The additional constraint from the neutron matter equation of state leads however to a somewhat too low saturation density of ρ 0 =0.134 fm -3 . We also investigate the effects of the NN-contact interaction on the complex single-particle potential U(p,k f )+iW(p,k f ). We find that the effective nucleon mass at the Fermi surface is bounded from below by M * (k f0 ) ≥1.4 M. This property keeps the critical temperature of the liquid-gas phase transition at somewhat too high values T c ≥21 MeV. The downward bending of the asymmetry energy A(k f ) above nuclear-matter saturation density is a generic feature of the approximation to fourth order. We furthermore investigate the effects of the NN-contact interaction on the (vector-∇ρ) 2 -term in the nuclear energy density functional E[ρ,τ]. Altogether, there is within this complete fourth-order calculation no ''magic'' set of adjustable short-range parameters with which one could reproduce simultaneously and accurately all semi-empirical properties of nuclear matter. In

  19. Research of Short-range Missile Motion in Terms of Different Wind Loads

    Directory of Open Access Journals (Sweden)

    A. N. Klishin

    2015-01-01

    Full Text Available When modeling the aircraft motion it is advisable to choose a particular model of the Earth, depending both on the task and on the required accuracy of calculation. The article describes various models of the Earth, such as the flat Earth with a plane-parallel field of gravity, spherical and non-rotating Earth with a plane-parallel field of gravity, spherical and non-rotating Earth with a central gravitational field, spherical and non-rotating Earth, taking into account the polar flattening of the Earth, spherical Earth based compression and polar daily rotation. The article also considers the influence of these models on the motion of the selected aircraft.To date, there is technical equipment to provide highly accurate description of the Earthshape, gravitational field, etc. The improved accuracy of the Earth model description results in more correct description of the trajectory and motion parameters of a ballistic missile. However, for short ranges (10-20 km this accuracy is not essential, and, furthermore, it increases time of calculation. Therefore, there is a problem of choosing the optimal description of the Earth parameters.The motion in the model of the Earth, which takes into account a daily rotation of the planet and polar flattening, is discussed in more detail, and the geographical latitude impact on coordinates of the points of fall of a ballistic missile is analyzed on the basis of obtained graphs.The article individually considers a problem of the wind effect on the aircraft motion and defines dependences of the missile motion on the parameters of different wind loads, such as wind speed and height of its action.A mathematical model of the missile motion was built and numerically integrated, using the Runge-Kutta 4th order method, for implementation and subsequent analysis.Based on the analysis of the calculation results in the abovementioned models of the Earth, differences in impact of these models on the parameters of the

  20. Short-range solar radiation forecasts over Sweden

    Directory of Open Access Journals (Sweden)

    T. Landelius

    2018-04-01

    Full Text Available In this article the performance for short-range solar radiation forecasts by the global deterministic and ensemble models from the European Centre for Medium-Range Weather Forecasts (ECMWF is compared with an ensemble of the regional mesoscale model HARMONIE-AROME used by the national meteorological services in Sweden, Norway and Finland. Note however that only the control members and the ensemble means are included in the comparison. The models resolution differs considerably with 18 km for the ECMWF ensemble, 9 km for the ECMWF deterministic model, and 2.5 km for the HARMONIE-AROME ensemble.The models share the same radiation code. It turns out that they all underestimate systematically the Direct Normal Irradiance (DNI for clear-sky conditions. Except for this shortcoming, the HARMONIE-AROME ensemble model shows the best agreement with the distribution of observed Global Horizontal Irradiance (GHI and DNI values. During mid-day the HARMONIE-AROME ensemble mean performs best. The control member of the HARMONIE-AROME ensemble also scores better than the global deterministic ECMWF model. This is an interesting result since mesoscale models have so far not shown good results when compared to the ECMWF models.Three days with clear, mixed and cloudy skies are used to illustrate the possible added value of a probabilistic forecast. It is shown that in these cases the mesoscale ensemble could provide decision support to a grid operator in terms of forecasts of both the amount of solar power and its probabilities.

  1. In-medium short-range dynamics of nucleons: Recent theoretical and experimental advances

    Energy Technology Data Exchange (ETDEWEB)

    Atti, Claudio Ciofi degli, E-mail: ciofi@pg.infn.it

    2015-08-14

    The investigation of in-medium short-range dynamics of nucleons, usually referred to as the study of short-range correlations (SRCs), is a key issue in nuclear and hadronic physics. As a matter of fact, even in the simplified assumption that the nucleus could be described as a system of protons and neutrons interacting via effective nucleon–nucleon (NN) interactions, several non trivial problems arise concerning the description of in-medium (NN short-range dynamics, namely: (i) the behavior of the NN interaction at short inter-nucleon distances in medium cannot be uniquely constrained by the experimental NN scattering phase shifts due to off-shell effects; (ii) by rigorous renormalization group (RG) techniques entire families of phase equivalent interactions differing in the short-range part can be derived; (iii) the in-medium NN interaction may be, in principle, different from the free one; (iv) when the short inter-nucleon separation is of the order of the nucleon size, the question arises of possible effects from quark and gluon degrees of freedom. For more than fifty years, experimental evidence of SRCs has been searched by means of various kinds of nuclear reactions, without however convincing results, mainly because the effects of SRCs arise from non observable quantities, like, e.g., the momentum distributions, and have been extracted from observable cross sections where short- and long-range effects, effects from nucleonic and non nucleonic degrees of freedom, and effects from final state interaction, could not be unambiguously separated out. Recent years, however, were witness of new progress in the field: from one side, theoretical and computational progress has allowed one to solve ab initio the many-nucleon non relativistic Schrödinger equation in terms of realistic NN interactions, obtaining realistic microscopic wave functions, unless the case of parametrized wave functions used frequently in the past, moreover the development of advanced

  2. Link Design Rules for Cost-Effective Short-Range Radio Over Multimode Fiber Systems

    DEFF Research Database (Denmark)

    Visani, Davide; Tartarini, Giovanni; Petersen, Martin Nordal

    2010-01-01

    Referring to short-range radio over multimode fiber links, we find out important guidelines for the realization of cost-effective intensity modulated directly detected systems. Since the quality of today's connectors is considerably higher than in the past, we demonstrate that two important...... parameters of the system are the finite detecting area of the photodiode and the laser frequency chirp. Furthemore, we show that the use of the central launch technique inherently determines a lower impact of modal noise fluctuations with respect to the offset launch one. This makes CL more convenient...

  3. Study of an Ising model with competing long- and short-range interactions

    International Nuclear Information System (INIS)

    Loew, U.; Emery, V.J.; Fabricius, K.; Kivelson, S.A.

    1994-01-01

    A classical spin-one lattice gas model is used to study the competition between short-range ferromagnetic coupling and long-range antiferromagnetic Coulomb interactions. The model is a coarse-grained representation of frustrated phase separation in high-temperature superconductors. The ground states are determined for the complete range of parameters by using a combination of numerical and analytical techniques. The crossover between ferromagnetic and antiferromagnetic states proceeds via a rich structure of highly symmetric striped and checkerboard phases. There is no devil's staircase behavior because mixtures of stripes with different period phase separate

  4. Renormalization group analysis of order parameter fluctuations in fermionic superfluids

    International Nuclear Information System (INIS)

    Obert, Benjamin

    2014-01-01

    In this work fluctuation effects in two interacting fermion systems exhibiting fermionic s-wave superfluidity are analyzed with a modern renormalization group method. A description in terms of a fermion-boson theory allows an investigation of order parameter fluctuations already on the one-loop level. In the first project a quantum phase transition between a semimetal and a s-wave superfluid in a Dirac cone model is studied. The interplay between fermions and quantum critical fluctuations close to and at the quantum critical point at zero and finite temperatures are studied within a coupled fermion-boson theory. At the quantum critical point non-Fermi liquid and non-Gaussian behaviour emerge. Close to criticality several quantities as the susceptibility show a power law behaviour with critical exponents. We find an infinite correlation length in the entire semimetallic ground state also away from the quantum critical point. In the second project, the ground state of an s-wave fermionic superfluid is investigated. Here, the mutual interplay between fermions and order parameter fluctuations is studied, especially the impact of massless Goldstone fluctuations, which occur due to spontaneous breaking of the continuous U(1)-symmetry. Fermionic gap and bosonic order parameter are distinguished. Furthermore, the bosonic order parameter is decomposed in transverse and longitudinal fluctuations. The mixing between transverse and longitudinal fluctuations is included in our description. Within a simple truncation of the fermion-boson RG flow, we describe the fermion-boson theory for the first time in a consistent manner. Several singularities appear due the Goldstone fluctuations, which partially cancel due to symmetry. Our RG flow captures the correct infrared asymptotics of the system, where the collective excitations act as an interacting Bose gas. Lowest order Ward identities and the massless Goldstone mode are fulfilled in our truncation.

  5. Microscopic analysis of order parameters in nuclear quantum phase transitions

    International Nuclear Information System (INIS)

    Li, Z. P.; Niksic, T.; Vretenar, D.; Meng, J.

    2009-01-01

    Microscopic signatures of nuclear ground-state shape phase transitions in Nd isotopes are studied using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. As a function of the physical control parameter, the number of nucleons, energy gaps between the ground state and the excited vibrational states with zero angular momentum, isomer shifts, and monopole transition strengths exhibit sharp discontinuities at neutron number N=90, which is characteristic of a first-order quantum phase transition.

  6. Anyonic order parameters for discrete gauge theories on the lattice

    International Nuclear Information System (INIS)

    Bais, F.A.; Romers, J.C.

    2009-01-01

    We present a new family of gauge invariant non-local order parameters Δ α A for (non-abelian) discrete gauge theories on a Euclidean lattice, which are in one-to-one correspondence with the excitation spectrum that follows from the representation theory of the quantum double D(H) of the finite group H. These combine magnetic flux-sector labeled by a conjugacy class with an electric representation of the centralizer subgroup that commutes with the flux. In particular, cases like the trivial class for magnetic flux, or the trivial irrep for electric charge, these order parameters reduce to the familiar Wilson and the 't Hooft operators, respectively. It is pointed out that these novel operators are crucial for probing the phase structure of a class of discrete lattice models we define, using Monte Carlo simulations.

  7. Nodes in an alternatively defined order parameter in HTSC

    Science.gov (United States)

    Nettel, Stephen

    2008-10-01

    In a previous study the BCS wave function was generalized to include the motion of the center-of-mass of Cooper pairs. It was found that the Ginsburg-Landau order parameter could be identified with a wave function describing this motion. Here attention is focussed on the effects of replacing free electron orbitals by Bloch waves. In the copper oxides, where the Fermi surface lies contiguous to the Brillouin zone boundary, and with pairs coupled by soft phonon modes, limitations on the wave vectors associated with the center-of-mass coordinates are found. These limitations lead to nodes in the Fourier transform of the Ginsburg-Landau order parameter. Possible relevance of the nodes to the more recently discovered properties of high TC superconductors is discussed.

  8. Nodes in an alternatively defined order parameter in HTSC

    International Nuclear Information System (INIS)

    Nettel, Stephen

    2008-01-01

    In a previous study the BCS wave function was generalized to include the motion of the center-of-mass of Cooper pairs. It was found that the Ginsburg-Landau order parameter could be identified with a wave function describing this motion. Here attention is focussed on the effects of replacing free electron orbitals by Bloch waves. In the copper oxides, where the Fermi surface lies contiguous to the Brillouin zone boundary, and with pairs coupled by soft phonon modes, limitations on the wave vectors associated with the center-of-mass coordinates are found. These limitations lead to nodes in the Fourier transform of the Ginsburg-Landau order parameter. Possible relevance of the nodes to the more recently discovered properties of high T C superconductors is discussed

  9. Infinitely robust order and local order-parameter tulips in Apollonian networks with quenched disorder

    Science.gov (United States)

    Kaplan, C. Nadir; Hinczewski, Michael; Berker, A. Nihat

    2009-06-01

    For a variety of quenched random spin systems on an Apollonian network, including ferromagnetic and antiferromagnetic bond percolation and the Ising spin glass, we find the persistence of ordered phases up to infinite temperature over the entire range of disorder. We develop a renormalization-group technique that yields highly detailed information, including the exact distributions of local magnetizations and local spin-glass order parameters, which turn out to exhibit, as function of temperature, complex and distinctive tulip patterns.

  10. Strong orientational coordinates and orientational order parameters for symmetric objects

    International Nuclear Information System (INIS)

    Haji-Akbari, Amir; Glotzer, Sharon C

    2015-01-01

    Recent advancements in the synthesis of anisotropic macromolecules and nanoparticles have spurred an immense interest in theoretical and computational studies of self-assembly. The cornerstone of such studies is the role of shape in self-assembly and in inducing complex order. The problem of identifying different types of order that can emerge in such systems can, however, be challenging. Here, we revisit the problem of quantifying orientational order in systems of building blocks with non-trivial rotational symmetries. We first propose a systematic way of constructing orientational coordinates for such symmetric building blocks. We call the arising tensorial coordinates strong orientational coordinates (SOCs) as they fully and exclusively specify the orientation of a symmetric object. We then use SOCs to describe and quantify local and global orientational order, and spatiotemporal orientational correlations in systems of symmetric building blocks. The SOCs and the orientational order parameters developed in this work are not only useful in performing and analyzing computer simulations of symmetric molecules or particles, but can also be utilized for the efficient storage of rotational information in long trajectories of evolving many-body systems. (paper)

  11. Kernel methods for interpretable machine learning of order parameters

    Science.gov (United States)

    Ponte, Pedro; Melko, Roger G.

    2017-11-01

    Machine learning is capable of discriminating phases of matter, and finding associated phase transitions, directly from large data sets of raw state configurations. In the context of condensed matter physics, most progress in the field of supervised learning has come from employing neural networks as classifiers. Although very powerful, such algorithms suffer from a lack of interpretability, which is usually desired in scientific applications in order to associate learned features with physical phenomena. In this paper, we explore support vector machines (SVMs), which are a class of supervised kernel methods that provide interpretable decision functions. We find that SVMs can learn the mathematical form of physical discriminators, such as order parameters and Hamiltonian constraints, for a set of two-dimensional spin models: the ferromagnetic Ising model, a conserved-order-parameter Ising model, and the Ising gauge theory. The ability of SVMs to provide interpretable classification highlights their potential for automating feature detection in both synthetic and experimental data sets for condensed matter and other many-body systems.

  12. Observations of multiple order parameters in 5f electron systems

    International Nuclear Information System (INIS)

    Blackburn, E.

    2005-12-01

    In this thesis, multiple order parameters originating in the same electronic system are studied. The multi-k magnetic structures, where more than one propagation wavevector, k, is observed in the same volume, are considered as prototypical models. The effect of this structure on the elastic and inelastic response is studied. In cubic 3-k uranium rock-salts, unexpected elastic diffraction events were observed at positions in reciprocal space where the structure factor should have been zero. These diffraction peaks are identified with correlations between the (orthogonal) magnetic order parameters. The 3-k structure also affects the observed dynamics; the spin-wave fluctuations in uranium dioxide as observed by inelastic neutron polarization analysis can only be explained on the basis of a 3-k structure. In the antiferromagnetic superconductor UPd 2 Al 3 the magnetic order and the super-conducting state coexist, and are apparently generated by the same heavy fermions. The effect of an external magnetic field on both the normal and superconducting states is examined. In the normal state, the compound displays Fermi-liquid-like behaviour. The inelastic neutron response is strongly renormalized on entering the superconducting state, and high-precision measurements of the low-energy transfer part of this response confirm that the superconducting energy gap has the same symmetry as the antiferromagnetic lattice. (author)

  13. Short-range effects in large white dwarfs

    International Nuclear Information System (INIS)

    Membrado, M.C.; Pacheco, A.F.

    1988-01-01

    Recent work of Membrado and Pacheco (1988) on the implication of Yukawa-like effects in small white dwarfs is extended to analyze the very massive case. Although the role of these impurities grows substantially as the radius of the star decreases, when reasonable supergravity parameters are used the predicted change in the white dwarf mass-radius relation is unobservably small. 8 references

  14. Implementation of Polar WRF for short range prediction of weather ...

    Indian Academy of Sciences (India)

    An inter-comparison of the time series of daily mean sea level pressure and sur- face winds of Maitri ..... face winds are two important parameters from the forecasting point of .... Forecast para- meters considered for this exercise are: (a) mean.

  15. Competing order parameters in Fermi systems with engineered band dispersion

    Science.gov (United States)

    Wu, Chien-Te; Boyack, Rufus; Anderson, Brandon; Levin, K.

    We explore a variety of competing phases in 2D and 3D Fermi gases in the presence of novel dispersion relations resulting from a shaken optical lattice. We incorporate spin imbalance along with attractive interactions. In 3D, at the mean field level we present phase diagrams reflecting the stability of alternative order parameters in the pairing (including LOFF) and charge density wave channels. We perform analogous studies in 2D, where we focus on the competition between different paired phases. Important in this regard is that our 2D studies are consistent with the Mermin Wagner theorem, so that, while there is competition, conventional superfluidity cannot occur

  16. Ordering dynamics of microscopic models with nonconserved order parameter of continuous symmetry

    DEFF Research Database (Denmark)

    Zhang, Z.; Mouritsen, Ole G.; Zuckermann, Martin J.

    1993-01-01

    crystals. For both models, which have a nonconserved order parameter, it is found that the linear scale, R(t), of the evolving order, following quenches to below the transition temperature, grows at late times in an effectively algebraic fashion, R(t)∼tn, with exponent values which are strongly temperature......Numerical Monte Carlo temperature-quenching experiments have been performed on two three-dimensional classical lattice models with continuous ordering symmetry: the Lebwohl-Lasher model [Phys. Rev. A 6, 426 (1972)] and the ferromagnetic isotropic Heisenberg model. Both models describe a transition...... from a disordered phase to an orientationally ordered phase of continuous symmetry. The Lebwohl-Lasher model accounts for the orientational ordering properties of the nematic-isotropic transition in liquid crystals and the Heisenberg model for the ferromagnetic-paramagnetic transition in magnetic...

  17. A novel nuclear dependence of nucleon–nucleon short-range correlations

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Hongkai [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Rong, E-mail: rwang@impcas.ac.cn [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Lanzhou University, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Huang, Yin [Lanzhou University, Lanzhou 730000 (China); Chen, Xurong [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2017-06-10

    A linear correlation is found between the magnitude of nucleon–nucleon short-range correlations and the nuclear binding energy per nucleon with pairing energy removed. By using this relation, the strengths of nucleon–nucleon short-range correlations of some unmeasured nuclei are predicted. Discussions on nucleon–nucleon pairing energy and nucleon–nucleon short-range correlations are made. The found nuclear dependence of nucleon–nucleon short-range correlations may shed some lights on the short-range structure of nucleus.

  18. Short range correlations in high energy heavy ion collisions

    International Nuclear Information System (INIS)

    Franco, V.; Nutt, W.T.

    1978-01-01

    We present a technique for including the effects of nucleon-nucleon correlations in the optical phase shift (chi) expansion of the nucleus-nucleus scattering amplitude and present the results for chi to second order. The total and inelastic cross sections are consistently higher than those obtained ignoring correlations, and are in better agreement with the data. Furthermore, the inclusion of correlations leads to second order phase shift functions which do not violate unitarity, in constrast to the case when correlations are ignored in very heavy nuclei (A 1 , A 2 > or approx. = 200). In elastic scattering differential cross sections, the effects of correlations can be quite large

  19. Short-range correlations in an extended time-dependent mean-field theory

    International Nuclear Information System (INIS)

    Madler, P.

    1982-01-01

    A generalization is performed of the time-dependent mean-field theory by an explicit inclusion of strong short-range correlations on a level of microscopic reversibility relating them to realistic nucleon-nucleon forces. Invoking a least action principle for correlated trial wave functions, equations of motion for the correlation functions and the single-particle model wave function are derived in lowest order of the FAHT cluster expansion. Higher order effects as well as long-range correlations are consider only to the extent to which they contribute to the mean field via a readjusted phenomenological effective two-body interaction. The corresponding correlated stationary problem is investigated and appropriate initial conditions to describe a heavy ion reaction are proposed. The singleparticle density matrix is evaluated

  20. Effects of short range ΔN interaction on observables of the πNN system

    International Nuclear Information System (INIS)

    Alexandrou, C.; Blankleider, B.

    1990-01-01

    The inadequacy of standard few-body approaches in describing the πNN system has motivated searches for the responsible missing mechanism. In the case of πd scattering, it has recently been asserted that an additional short range ΔN interaction can account for essentially all the discrepancies between a few-body calculation and experimental data. This conclusion, however, has been based on calculations where a phenomenological ΔN interaction is added only in Born term to background few-body amplitudes. In the present work we investigate the effect of including such a ΔN interaction to all orders within a unitary few-body calculation of the πNN system. Besides testing the validity of adding the ΔN interaction in Born term in πd scattering, our fully coupled approach also enables us to see the influence of the same ΔN interaction on the processes NN→πd and NN→NN. For πd elastic scattering, we find that the higher order ΔN interaction terms can have as much influence on πd observables as the lowest order contribution alone. Moreover, we find that the higher order contributions tend to cancel the effect obtained by adding the ΔN interaction in Born term only. The effect of the same ΔN interaction on NN→πd and NN→NN appears to be as significant as in πd→πd, suggesting that future investigations of the short range ΔN interaction should be done in the context of the fully coupled πNN system

  1. A brief note on the magnecule order parameter upgrade hypothesis

    International Nuclear Information System (INIS)

    Schmidt, Nathan O.

    2015-01-01

    In this short remark, we report on recent hypothetical work that aims to equip Santilli’s magnecule model with topological deformation order parameters (OP) of fractional statistics to define a preliminary set of wavepacket wavefunctions for the electron toroidal polarizations. The primary objective is to increase the representational precision and predictive accuracy of the magnecule model by exemplifying the fluidic characteristics for direct industrial application. In particular, the OPs are deployed to encode the spontaneous superfluidic gauge symmetry breaking (which may be restored at the iso-topic level) and correlated with Leggett’s superfluid B phases to establish a long range constraint for the wavefunctions. These new, developing, theoretical results may be significant because the OP configuration arms us with an extra degree of freedom for encoding a magnecule’s states and transitions, which may reveal further insight into the underlying physical mechanisms and features associated with these state-of-the-art magnecular bonds

  2. Reduction of the chiral order parameter by a nuclear medium

    International Nuclear Information System (INIS)

    Kienle, P.; Yamazaki, Toshimizu

    2001-01-01

    We propose a model independent procedure to deduce from the 1s-binding energy of heavy, neutron rich pionic atoms, the isovector scattering length b 1 of the pion nucleus interaction. It is related to the pion decay constant f π , the order parameter of spontaneous chiral symmetry breaking and thus to the value of the chiral quark condensate. Based on the results with pionic 205 Pb, we find with the assertion that only the isovector part of the pion-nucleus interaction be modified by a QCD effect, a reduction of the quark condensate by 30% in a 205 Pb nucleus. Forthcoming experiments to measure pionic 1s-binding energies in Sn-isotopes, including isotope shifts, will yield decisive information on the quark condensate without assertion. (orig.)

  3. Mutual information as an order parameter for quantum synchronization

    Science.gov (United States)

    Ameri, V.; Eghbali-Arani, M.; Mari, A.; Farace, A.; Kheirandish, F.; Giovannetti, V.; Fazio, R.

    2015-01-01

    Spontaneous synchronization is a fundamental phenomenon, important in many theoretical studies and applications. Recently, this effect has been analyzed and observed in a number of physical systems close to the quantum-mechanical regime. In this work we propose mutual information as a useful order parameter which can capture the emergence of synchronization in very different contexts, ranging from semiclassical to intrinsically quantum-mechanical systems. Specifically, we first study the synchronization of two coupled Van der Pol oscillators in both classical and quantum regimes and later we consider the synchronization of two qubits inside two coupled optical cavities. In all these contexts, we find that mutual information can be used as an appropriate figure of merit for determining the synchronization phases independently of the specific details of the system.

  4. Resonant tunnelling through short-range singular potentials

    International Nuclear Information System (INIS)

    Zolotaryuk, A V; Christiansen, P L; Iermakova, S V

    2007-01-01

    A three-parameter family of point interactions constructed from sequences of symmetric barrier-well-barrier and well-barrier-well rectangles is studied in the limit, when the rectangles are squeezed to zero width but the barrier height and the well depth become infinite (the zero-range limit). The limiting generalized potentials are referred to as the second derivative of Dirac's delta function ±λδ-prime(x) with a renormalized coupling constant λ > 0 or simply as ±δ-prime-like point interactions. As a result, a whole family of self-adjoint extensions of the one-dimensional Schroedinger operator is shown to exist, which results in full and partial resonant tunnelling through this class of singular potentials. The resonant tunnelling occurs for countable sets of interaction strength values in the λ-space which are the roots of several transcendental equations. The comparison with the previous results for δ'-like point interactions is also discussed

  5. Ionization induced by strong electromagnetic field in low dimensional systems bound by short range forces

    Energy Technology Data Exchange (ETDEWEB)

    Eminov, P.A., E-mail: peminov@mail.ru [Moscow State University of Instrument Engineering and Computer Sciences, 20 Stromynka Street, Moscow 2107996 (Russian Federation); National Research University Higher School of Economics, 3/12 Bolshoy Trekhsvyatskiy pereulok, Moscow 109028 (Russian Federation)

    2013-10-01

    Ionization processes for a two dimensional quantum dot subjected to combined electrostatic and alternating electric fields of the same direction are studied using quantum mechanical methods. We derive analytical equations for the ionization probability in dependence on characteristic parameters of the system for both extreme cases of a constant electric field and of a linearly polarized electromagnetic wave. The ionization probabilities for a superposition of dc and low frequency ac electric fields of the same direction are calculated. The impulse distribution of ionization probability for a system bound by short range forces is found for a superposition of constant and alternating fields. The total probability for this process per unit of time is derived within exponential accuracy. For the first time the influence of alternating electric field on electron tunneling probability induced by an electrostatic field is studied taking into account the pre-exponential term.

  6. Molecular dynamics simulations of short-range force systems on 1024-node hypercubes

    International Nuclear Information System (INIS)

    Plimpton, S.J.

    1990-01-01

    In this paper, two parallel algorithms for classical molecular dynamics are presented. The first assigns each processor to a subset of particles; the second assigns each to a fixed region of 3d space. The algorithms are implemented on 1024-node hypercubes for problems characterized by short-range forces, diffusion (so that each particle's neighbors change in time), and problem size ranging from 250 to 10000 particles. Timings for the algorithms on the 1024-node NCUBE/ten and the newer NCUBE 2 hypercubes are given. The latter is found to be competitive with a CRAY-XMP, running an optimized serial algorithm. For smaller problems the NCUBE 2 and CRAY-XMP are roughly the same; for larger ones the NCUBE 2 is up to twice as fast. Parallel efficiencies of the algorithms and communication parameters for the two hypercubes are also examined

  7. Contribution of silicon recombination properties in resolution of short-range particle detectors

    International Nuclear Information System (INIS)

    Verbitskaya, E.M.; Eremin, V.K.; Malyarenko, A.M.; Strokan, N.B.; Sukhanov, V.L.

    1987-01-01

    Tracks of short-range particles represent dense clusters of electron-hole pairs 2-4 μm in diameter and 20-30 μm long. Thus, conditions for charge carrier transport in microscopic Si volume are discovered at registration of each particle. Statistical distribution by the specimen square of the main parameter - lifetime of charge carriers (τ) is disclosed as a result of particle chaotic hitting the detector. Analytical description for the shape of the spectral line of the detector is found in the assumption of Gauss distribution τ. The function is applied to the analysis of detector spectra with maximum energy resolution, for which contributions to the shape of the line of the fundamental factors and nonperfection of Si or of the detector structure as a whole are comparable. Excess fluctuations of α-particle energy transformation to the charge of electron-hole pairs are found relatively to adopted values

  8. Contribution of silicon recombination properties in resolution of short-range particle detectors

    Energy Technology Data Exchange (ETDEWEB)

    Verbitskaya, E M; Eremin, V K; Malyarenko, A M; Strokan, N B; Sukhanov, V L

    1987-10-01

    Tracks of short-range particles represent dense clusters of electron-hole pairs 2-4 ..mu..m in diameter and 20-30 ..mu..m long. Thus, conditions for charge carrier transport in microscopic Si volume are discovered at registration of each particle. Statistical distribution by the specimen square of the main parameter - lifetime of charge carriers (tau) is disclosed as a result of particle chaotic hitting the detector. Analytical description for the shape of the spectral line of the detector is found in the assumption of Gauss distribution tau. The function is applied to the analysis of detector spectra with maximum energy resolution, for which contributions to the shape of the line of the fundamental factors and nonperfection of Si or of the detector structure as a whole are comparable. Excess fluctuations of ..cap alpha..-particle energy transformation to the charge of electron-hole pairs are found relatively to adopted values.

  9. Microscopic nucleon spectral function for finite nuclei featuring two- and three-nucleon short-range correlations: The model versus ab initio calculations for three-nucleon systems

    Science.gov (United States)

    Ciofi degli Atti, Claudio; Mezzetti, Chiara Benedetta; Morita, Hiko

    2017-04-01

    order of magnitude less than the effect of two-nucleon short-range correlations. Conclusions: The convolution model of the spectral function of the three-nucleon systems featuring both two- and three-nucleon short-range correlations and correctly depending upon the ab initio two-nucleon relative and center-of-mass momentum distributions provides in the correlation region a satisfactory approximation of the spectral function in a wide range of momentum and removal energy. The extension of the model to complex nuclei is expected to provide a realistic microscopic parameter-free model of the spectral function, whose properties are therefore governed by the features of realistic two-nucleon interactions and the momentum distributions in a given nucleus.

  10. Thermal algebraic-decay charge liquid driven by competing short-range Coulomb repulsion

    Science.gov (United States)

    Kaneko, Ryui; Nonomura, Yoshihiko; Kohno, Masanori

    2018-05-01

    We explore the possibility of a Berezinskii-Kosterlitz-Thouless-like critical phase for the charge degrees of freedom in the intermediate-temperature regime between the charge-ordered and disordered phases in two-dimensional systems with competing short-range Coulomb repulsion. As the simplest example, we investigate the extended Hubbard model with on-site and nearest-neighbor Coulomb interactions on a triangular lattice at half filling in the atomic limit by using a classical Monte Carlo method, and find a critical phase, characterized by algebraic decay of the charge correlation function, belonging to the universality class of the two-dimensional XY model with a Z6 anisotropy. Based on the results, we discuss possible conditions for the critical phase in materials.

  11. Dependence of Coulomb Sum Rule on the Short Range Correlation by Using Av18 Potential

    Science.gov (United States)

    Modarres, M.; Moeini, H.; Moshfegh, H. R.

    The Coulomb sum rule (CSR) and structure factor are calculated for inelastic electron scattering from nuclear matter at zero and finite temperature in the nonrelativistic limit. The effect of short-range correlation (SRC) is presented by using lowest order constrained variational (LOCV) method and the Argonne Av18 and Δ-Reid soft-core potentials. The effects of different potentials as well as temperature are investigated. It is found that the nonrelativistic version of Bjorken scaling approximately sets in at the momentum transfer of about 1.1 to 1.2 GeV/c and the increase of temperature makes it to decrease. While different potentials do not significantly change CSR, the SRC improves the Coulomb sum rule and we get reasonably close results to both experimental data and others theoretical predictions.

  12. Observation of short range three-particle correlations in e+e- annihilations at LEP energies

    CERN Document Server

    Abreu, P; Adye, T; Agasi, E; Ajinenko, I; Aleksan, Roy; Alekseev, G D; Allport, P P; Almehed, S; Alvsvaag, S J; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Apel, W D; Arnoud, Y; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barate, R; Barbiellini, Guido; Bardin, Dimitri Yuri; Barker, G J; Baroncelli, A; Barrio, J A; Bartl, Walter; Barão, F; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Belous, K S; Benvenuti, Alberto C; Berggren, M; Bertrand, D; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bloch, D; Blume, M; Blyth, S; Bocci, V; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Borisov, G; Bosio, C; Bosworth, S; Botner, O; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenner, R A; Bricman, C; Brillault, L; Brown, R C A; Brunet, J M; Brückman, P; Bugge, L; Buran, T; Buys, A; Bärring, O; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carrilho, P; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Cerrito, L; Chabaud, V; Charpentier, P; Chaussard, L; Chauveau, J; Checchia, P; Chelkov, G A; Chierici, R; Chochula, P; Chorowicz, V; Cindro, V; Collins, P; Contreras, J L; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; D'Almagne, B; Da Silva, W; Dahl-Jensen, Erik; Dahm, J; Dam, M; Damgaard, G; Daum, A; Dauncey, P D; Davenport, Martyn; De Angelis, A; De Boeck, H; De Brabandere, S; De Clercq, C; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Defoix, C; Della Ricca, G; Delpierre, P A; Demaria, N; Di Ciaccio, Lucia; Dijkstra, H; Djama, F; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Dufour, Y; Dupont, F; Dönszelmann, M; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Ershaidat, N; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Fenyuk, A; Ferrer, A; Filippas-Tassos, A; Firestone, A; Fischer, P A; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Föth, H; Fürstenau, H; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gibbs, M; Gillespie, D; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Gracco, Valerio; Graziani, E; Grosdidier, G; Gunnarsson, P; Guy, J; Guz, Yu; Górski, M; Günther, M; Haedinger, U; Hahn, F; Hahn, M; Hahn, S; Hajduk, Z; Hallgren, A; Hamacher, K; Hao, W; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Houlden, M A; Huet, K; Hultqvist, K; Ioannou, P; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Joram, Christian; Juillot, P; Jönsson, L B; Jönsson, P E; Kaiser, M; Kalmus, George Ernest; Kapusta, F; Karlsson, M; Karvelas, E; Katargin, A; Katsanevas, S; Katsoufis, E C; Keränen, R; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klein, H; Klovning, A; Kluit, P M; Kokkinias, P; Koratzinos, M; Kostyukhin, V; Kourkoumelis, C; Kramer, P H; Krammer, Manfred; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Królikowski, J; Kubinec, P; Kucewicz, W; Kurvinen, K L; Kuznetsov, O; Köhne, J H; Köne, B; La Vaissière, C de; Lacasta, C; Laktineh, I; Lamblot, S; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Last, I; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemoigne, Y; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lokajícek, M; Loken, J G; Loukas, D; Lutz, P; Lyons, L; López, J M; López-Aguera, M A; López-Fernandez, A; Lörstad, B; MacNaughton, J N; Maehlum, G; Maio, A; Malychev, V; Mandl, F; Marco, J; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Maron, T; Martí i García, S; Martínez-Rivero, C; Martínez-Vidal, F; Maréchal, B; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Meroni, C; Meyer, W T; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Monge, M R; Morettini, P; Mundim, L M; Murray, W J; Muryn, B; Myagkov, A; Myatt, Gerald; Mönig, K; Møller, R; Müller, H; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Negri, P; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Némécek, S; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Palka, H; Papadopoulou, T D; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernegger, H; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Phillips, H T; Piana, G; Pierre, F; Pimenta, M; Plaszczynski, S; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Prest, M; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Rosso, E; Roudeau, Patrick; Rovelli, T; Ruhlmann-Kleider, V; Ruiz, A; Rídky, J; Rückstuhl, W; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sajot, G; Salt, J; Sannino, M; Schneider, H; Schyns, M A E; Sciolla, G; Scuri, F; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Shellard, R C; Siccama, I; Siegrist, P; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sokolov, A; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Squarcia, S; Stanescu, C; Stapnes, Steinar; Stavitski, I; Stepaniak, K; Stichelbaut, F; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Stäck, H; Szczekowski, M; Szeptycka, M; Sánchez, J; Tabarelli de Fatis, T; Tavernet, J P; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Toet, D Z; Tomaradze, A G; Tomé, B; Tortora, L; Tranströmer, G; Treille, D; Trischuk, W; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Ullaland, O; Valenti, G; Vallazza, E; Van Eldik, J; Van der Velde, C; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Wehr, A; Weierstall, M; Weilhammer, Peter; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Woschnagg, K; Yip, K; Yushchenko, O P; Zach, F; Zacharatou-Jarlskog, C; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zito, M; Zontar, D; Zuberi, R; Zucchelli, G C; Zumerle, G; de Boer, Wim; van Apeldoorn, G W; van Dam, P; Åsman, B; Österberg, K; Überschär, B; Überschär, S

    1995-01-01

    \\def\\tpc{three-particle correlation} \\def\\twopc{two-particle correlation} Measurements are presented of short range three-particle correlations in e^+ e^- annihilations at LEP using data collected by the DELPHI detector. %The jet structure is studied using three-particle correlation functions. At small values of the four-momentum difference, strong three-particle correlations are observed for like-sign (+++ and ---) and for unlike-sign (++- and +--) pion combinations which are not a consequence of two-particle correlations. A possible explanation of the observed effects in like-sign combinations is the existence of higher order Bose-Einstein interference, which significantly changes the particle distributions in jets.

  13. Microscopic interplay of superconducting and magnetic order parameters in ferropnictides

    Energy Technology Data Exchange (ETDEWEB)

    Maeter, H.; Goltz, T.; Spehling, J.; Klauss, H.H. [Institut fuer Festkoerperphysik, TU Dresden (Germany); Bendele, M.; Luetkens, H.; Khasanov, R.; Pascua, G.; Shermadini, Z.; Amato, A. [Laboratory for Muon-Spin Spectroscopy, Paul Scherrer Institut, Villigen (Switzerland); Aswartham, S.; Hamann-Borrero, J.E.; Kondrat, A.; Hess, C.; Wolter, A.; Wurmehl, S.; Behr, G.; Buechner, B. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden (Germany); Wiesenmayer, E.; Johrendt, D. [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany); Potts, H.; Banusch, B. [Swiss Nanoscience Institute, Universitaet Basel (Switzerland)

    2012-07-01

    We present results of {mu}SR experiments of Ba{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} that show a large coupling of the superconducting and magnetic order parameters. This is unexpected in light of the phase separation in Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2}. However, in a {mu}SR study of Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} we unambiguously showed microscopic coexistence, even though there are many reports of phase separation in this system. In FeSe{sub 1-x} the interplay of phase separation and microscopic coexistence is also evident, here pressure can induce a change from microscopic coexistence to a combination of both. In light of the {mu}SR results it seems likely that phase separation and microscopic coexistence depend on the microscopic properties much more than on disorder.

  14. Direct test of the Gaussian auxiliary field ansatz in nonconserved order parameter phase ordering dynamics

    Science.gov (United States)

    Yeung, Chuck

    2018-06-01

    The assumption that the local order parameter is related to an underlying spatially smooth auxiliary field, u (r ⃗,t ) , is a common feature in theoretical approaches to non-conserved order parameter phase separation dynamics. In particular, the ansatz that u (r ⃗,t ) is a Gaussian random field leads to predictions for the decay of the autocorrelation function which are consistent with observations, but distinct from predictions using alternative theoretical approaches. In this paper, the auxiliary field is obtained directly from simulations of the time-dependent Ginzburg-Landau equation in two and three dimensions. The results show that u (r ⃗,t ) is equivalent to the distance to the nearest interface. In two dimensions, the probability distribution, P (u ) , is well approximated as Gaussian except for small values of u /L (t ) , where L (t ) is the characteristic length-scale of the patterns. The behavior of P (u ) in three dimensions is more complicated; the non-Gaussian region for small u /L (t ) is much larger than that in two dimensions but the tails of P (u ) begin to approach a Gaussian form at intermediate times. However, at later times, the tails of the probability distribution appear to decay faster than a Gaussian distribution.

  15. Effect of Jahn-Teller distortion on the short range magnetic order in copper ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abdellatif, M.H., E-mail: Mohamed.abdellatif@iit.it [Nanostrctures Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Innocenti, Claudia [INSTM—Department of Chemistry, University of Florence, via della Lastruccia 3, I-50019 Sesto Fiorentino, FI (Italy); Liakos, Ioannis [Nanostrctures Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Scarpellini, Alice; Marras, Sergio [Nanochemistry Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy); Salerno, Marco [Nanostrctures Department, Istituto Italiano di Tecnologia, via Morego 30, I-16163 Genova (Italy)

    2017-02-15

    Copper ferrite of spinel crystal structure was synthesized in the form of nano-particles using citrate-gel auto-combustion method. The sample morphology and composition were identified using scanning electron microscopy, X-ray diffraction, and X-ray spectroscopy. The latter technique reveals an inverse spinel structure with Jahn-Teller tetragonal distortion. The static magnetization was measured using vibrating sample magnetometer. Magnetic force microscopy was used in combination with the magnetization data to demonstrate the finite size effect of the magnetic spins and their casting behavior due to the introduction of copper ions in the tetrahedral magnetic sub-lattices, which results in tetragonal distorting the spinel structure of the copper ferrite. The magnetic properties of materials are a result of the collective behavior of the magnetic spins, and magnetic force microscopy can probe the collective behavior of the magnetic spins in copper ferrite, yet providing a sufficient resolution to map the effects below the micrometer size scale, such as the magnetic spin canting. A theoretical study was done to clarify the finite size effect of Jahn-Teller distortion on the magnetic properties of the material. When the particles are in the nano-scale, below the single domain size, their magnetic properties are very sensitive to their size change. - Highlights: • The spin canting due to Jahn-Teller distortion in Copper ferrite can be detected using magnetic force microscope. • The contrast in the magnetic AFM image can be analyzed to give information not only about the surface spins but also about the canting of the core spins inside the aggregated cluster of magnetic nanoparticle.

  16. Investigation of short range order in Fe-C melts by neutron scattering

    International Nuclear Information System (INIS)

    Weber, M.; Steeb, S.

    1978-01-01

    Neutron diffraction measurements were done with Fe-C-melts (5; 13; and 17 at % C) using the method of isotopic substitution. The neutron small angle scattering effect observed could be explained by magnetic scattering, caused by spin-fluctuations still existing in the molten state far away from the Curie temperature. Total structure factors were calculated from observed intensities taking into account the correction for magnetic scattering. For each carbon concentration two alloys were investigated, one using iron of natural isotopic abundance and the other using enriched 57 Fe. From a comparison of the q-region below the first maximum of the total structure factor as obtained using Fesup(nat) or 57 Fe, respectively, a tendency to the preference of unlike nearest neighbours is concluded, the distance between Fe-C-pairs being 2.2 A. (orig.) [de

  17. Elastic properties and short-range structural order in mixed network former glasses.

    Science.gov (United States)

    Wang, Weimin; Christensen, Randilynn; Curtis, Brittany; Hynek, David; Keizer, Sydney; Wang, James; Feller, Steve; Martin, Steve W; Kieffer, John

    2017-06-21

    Elastic properties of alkali containing glasses are of great interest not only because they provide information about overall structural integrity but also they are related to other properties such as thermal conductivity and ion mobility. In this study, we investigate two mixed-network former glass systems, sodium borosilicate 0.2Na 2 O + 0.8[xBO 1.5 + (1 - x)SiO 2 ] and sodium borogermanate 0.2Na 2 O + 0.8[xBO 1.5 + (1 - x)GeO 2 ] glasses. By mixing network formers, the network topology can be changed while keeping the network modifier concentration constant, which allows for the effect of network structure on elastic properties to be analyzed over a wide parametric range. In addition to non-linear, non-additive mixed-glass former effects, maxima are observed in longitudinal, shear and Young's moduli with increasing atomic number density. By combining results from NMR spectroscopy and Brillouin light scattering with a newly developed statistical thermodynamic reaction equilibrium model, it is possible to determine the relative proportions of all network structural units. This new analysis reveals that the structural characteristic predominantly responsible for effective mechanical load transmission in these glasses is a high density of network cations coordinated by four or more bridging oxygens, as it provides for establishing a network of covalent bonds among these cations with connectivity in three dimensions.

  18. Temperature Dependence of Short-Range Order in β-Brass

    DEFF Research Database (Denmark)

    Dietrich, O.W.; Als-Nielsen, Jens Aage

    1967-01-01

    Critical scattering of neutrons around the superlattice reflections (1, 0, 0) and (1, 1, 1) from a single crystal of beta-brass has been measured at temperatures from 2 to 25deg C above the transition temperature. The temperature dependence of the critical peak intensity, proportional to the susc......Critical scattering of neutrons around the superlattice reflections (1, 0, 0) and (1, 1, 1) from a single crystal of beta-brass has been measured at temperatures from 2 to 25deg C above the transition temperature. The temperature dependence of the critical peak intensity, proportional...

  19. Dependability investigation of wireless short range embedded systems: hardware platform oriented approach

    NARCIS (Netherlands)

    Senouci, B.; Kerkhoff, Hans G.; Annema, Anne J.; Bentum, Marinus Jan

    2015-01-01

    A new direction in short-range wireless applications has appeared in the form of high-speed data communication devices for distances of hundreds meters. Behind these embedded applications, a complex heterogeneous architecture is built. Moreover, these short range communications are introduced into

  20. Air defense planning for an area with the use of very short range air defense sets

    Directory of Open Access Journals (Sweden)

    Tadeusz Pietkiewicz

    2017-12-01

    Full Text Available This paper presents a heuristic method of planning the deployment of very short-range anti-air missile and artillery sets (VSHORAD around an area (‘protected area’ in order to protect it. A function dependent on the distance between the earliest feasible points of destroying targets and the centre of the protected area was taken as an objective function. This is a different indicator from those commonly used in the literature, and based on the likelihood of a defense zone penetration by means of an air attack (MAA: the kill probability of the MAA and the probability of area losses. The model constraints resulted directly from the restrictions imposed by real air defense systems and the nature of the area being defended. This paper assumes that the VSHORAD system operates as a part of a general, superordinate air defense command and control system based on the idea of network-centric warfare, which provides the VSHORAD system with a recognized air picture, air defense plans, and combat mission specifications. The presented method has been implemented. The final part of the paper presents the computational results. Keywords: optimal planning, air defense system, area installation protection, deployment of very short range anti-air missile and artillery sets (VSHORAD

  1. Very-short range forecasting system for 2018 Pyeonchang Winter Olympic and Paralympic games

    Science.gov (United States)

    Nam, Ji-Eun; Park, Kyungjeen; Kim, Minyou; Kim, Changhwan; Joo, Sangwon

    2016-04-01

    The 23rd Olympic Winter and the 13th Paralympic Winter Games will be held in Pyeongchang, Republic of Korea respectively from 9 to 25 February 2018 and from 9 to 18 February 2018. The Korea Meteorological Administration (KMA) and the National Institute for Meteorological Science (NIMS) have the responsibility to provide weather information for the management of the Games and the safety of the public. NIMS will carry out a Forecast Demonstration Project (FDP) and a Research and Development Project (RDP) which will be called ICE-POP 2018. These projects will focus on intensive observation campaigns to understand severe winter weathers over the Pyeongchang region, and the research results from the RDP will be used to improve the accuracy of nowcasting and very short-range forecast systems during the Games. To support these projects, NIMS developed Very-short range Data Assimilation and Prediction System (VDAPS), which is run in real time with 1 hour cycling interval and up to 12 hour forecasts. The domain is covering Korean Peninsular and surrounding seas with 1.5km horizontal resolution. AWS, windprofiler, buoy, sonde, aircraft, scatwinds, and radar radial winds are assimilated by 3DVAR on 3km resolution inner domain. The rain rate is converted into latent heat and initialized via nudging. The visibility data are also assimilated with the addition of aerosol control variable. The experiments results show the improvement in rainfall over south sea of Korean peninsula. In order to reduce excessive rainfalls during first 2 hours due to the reduced cycling interval, the data assimilation algorithm is optimized.

  2. Short-range airborne transmission of expiratory droplets between two people

    DEFF Research Database (Denmark)

    Liu, Li; Li, Yuguo; Nielsen, Peter Vilhelm

    2017-01-01

    , ventilation, and breathing mode. Under the specific set of conditions studied, we found a substantial increase in airborne exposure to droplet nuclei exhaled by the source manikin when a susceptible manikin is within about 1.5 m of the source manikin, referred to as the proximity effect. The threshold...... distance of about 1.5 m distinguishes the two basic transmission processes of droplets and droplet nuclei, that is, short-range modes and the long-range airborne route. The short-range modes include both the conventional large droplet route and the newly defined short-range airborne transmission. We thus...... reveal that transmission occurring in close proximity to the source patient includes both droplet-borne (large droplet) and short-range airborne routes, in addition to the direct deposition of large droplets on other body surfaces. The mechanisms of the droplet-borne and short-range airborne routes...

  3. Introducing a new family of short-range potentials and their numerical solutions using the asymptotic iteration method

    Science.gov (United States)

    Assi, I. A.; Sous, A. J.

    2018-05-01

    The goal of this work is to derive a new class of short-range potentials that could have a wide range of physical applications, specially in molecular physics. The tridiagonal representation approach has been developed beyond its limitations to produce new potentials by requiring the representation of the Schrödinger wave operator to be multidiagonal and symmetric. This produces a family of Hulthén potentials that has a specific structure, as mentioned in the introduction. As an example, we have solved the nonrelativistic wave equation for the new four-parameter short-range screening potential numerically using the asymptotic iteration method, where we tabulated the eigenvalues for both s -wave and arbitrary l -wave cases in tables.

  4. Objectives for next generation of practical short-range atmospheric dispersion models

    International Nuclear Information System (INIS)

    Olesen, H.R.; Mikkelsen, T.

    1992-01-01

    The proceedings contains papers from the workshop ''Objectives for Next Generation of Practical Short-Range Atmospheric Dispersion Models''. They deal with two types of models, namely models for regulatory purposes and models for real-time applications. The workshop was the result of an action started in 1991 for increased cooperation and harmonization within atmospheric dispersion modelling. The focus of the workshop was on the management of model development and the definition of model objectives, rather than on detailed model contents. It was the intention to identify actions that can be taken in order to improve the development and use of atmospheric dispersion models. The papers in the proceedings deal with various topics within the broad spectrum of matters related to up-to-date practical models, such as their scientific basis, requirements for model input and output, meteorological preprocessing, standardisation within modelling, electronic information exchange as a potentially useful tool, model evaluation and data bases for model evaluation. In addition to the papers, the proceedings contain summaries of the discussions at the workshop. These summaries point to a number of recommended actions which can be taken in order to improve ''modelling culture''. (AB)

  5. Short Range Air Defense in Army Divisions: Do We Really Need It

    National Research Council Canada - National Science Library

    Anderson, Charles

    2000-01-01

    Ever since the Soviet threat collapsed, coupled with the demonstrated, overwhelming, capability of our air forces during numerous operations in the 1990s, the relevance of the Short Range Air Defense (SHORAD...

  6. Revision to dedicated short range communication roadside equipment specification - RSU 4.1.Bench Test Plan.

    Science.gov (United States)

    2017-04-28

    The document describes the overall process for evaluating Dedicated Short Range Communication (DSRC) Roadside Units (RSU) against USDOT RSU Specification 4.1 in preparation for field evaluation. The Test Cases contained in this document only evaluate...

  7. Probing short-range correlations in asymmetric nuclei with quasi-free pair knockout reactions

    Science.gov (United States)

    Stevens, Sam; Ryckebusch, Jan; Cosyn, Wim; Waets, Andreas

    2018-02-01

    Short-range correlations (SRC) in asymmetric nuclei with an unusual neutron-to-proton ratio can be studied with quasi-free two-nucleon knockout processes following the collision between accelerated ions and a proton target. We derive an approximate factorized cross section for those SRC-driven p (A ,p‧N1N2) reactions. Our reaction model hinges on the factorization properties of SRC-driven A (e ,e‧N1N2) reactions for which strong indications are found in theory-experiment comparisons. In order to put our model to the test we compare its predictions with results of 12C (p ,p‧ pn) measurements conducted at Brookhaven National Laboratory (BNL) and find a fair agreement. The model can also reproduce characteristic features of SRC-driven two-nucleon knockout reactions, like back-to-back emission of the correlated nucleons. We study the asymmetry dependence of nuclear SRC by providing predictions for the ratio of proton-proton to proton-neutron knockout cross sections for the carbon isotopes 9-15C thereby covering neutron excess values (N - Z) / Z between -0.5 and +0.5.

  8. Performance analysis of dedicated short range communications technology and overview of the practicability for developing countries

    Directory of Open Access Journals (Sweden)

    Vandana Bassoo

    2015-12-01

    Full Text Available Vehicular communication is a widely researched field and aims at developing technologies that may complement systems such as the advanced driver assistance systems. It is therefore important to analyse and infer on the performance of vehicular technologies for different driving and on-road criteria. This study considers the dedicated short range communications technology and more precisely the IEEE 802.11p standard for a performance and practicability analysis. There is also the proposal of a new classification scheme for typical driving conditions, which includes the main categories of Emergency and Safety scenarios while sub-classifications of Critical and Preventive Safety also exist. The scheme is used to build up scenarios as well as related equations relevant to developing countries for practical network simulation. The results obtained indicate that the relative speed of nodes is a determining factor in the overall performance and effectiveness of wireless vehicular communication systems. Moreover, delay values of low order were observed while an effective communication range of about 800 m was calculated for highway scenarios. The research thus indicates suitability of the system for an active use in collision avoidance even though independent factors such as climatic conditions and driver behaviour may affect its effectiveness in critical situations.

  9. Short-range ferromagnetism in alloy ribbons of Fe-Cr-Si-Nb-(Ag, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    THANH, P. Q.; HOA, N. Q.; CHAU, N. [Vietnam National University, Hanoi (Viet Nam); HUU, C. X. [Danang University of Technology, Danang (Viet Nam); NGO, D. T. [Technical University of Denmark, Kgs. Lyngby (Denmark); PHAN, T. L. [Chungbuk National University, Cheongju (Korea, Republic of)

    2014-04-15

    We have studied the magnetic properties of two amorphous alloy ribbons Fe{sub 72}Cr{sub 6}Si{sub 4}Nb{sub 5}B{sub 12}Ag{sub 1} (FCSNB-Ag) and Fe{sub 72}Cr{sub 6}Si{sub 4}Nb{sub 5}B{sub 12}Cu{sub 1} (FCSNB-Cu), prepared by using a melt-spinning technique. Magnetization (M) measurements for various temperatures (T) and magnetic fields (H) indicate that ferromagnetic-paramagnetic (FM-PM) phase transitions take place in FCSNB-Ag and FCSNB-Cu at Curie temperatures (T{sub C} ) of about 308.3 K and 322.5 K, respectively. Analyses of M - H data at different temperatures in the vicinity of the FM-PM phase transition based on the modified Arrott plot method and scaling hypothesis yielded the exponent values of β = 0.369 ± 0.005, γ = 1.359 ± 0.005 and δ = 4.7 ± 0.1 for FCSNB-Ag, and β = 0.376 ± 0.002, γ = 1.315 ± 0.006 and δ = 4.5 ± 0.1 for FCSNB-Cu. Compared with the values from theoretical models, these values are close to those expected for the 3D Heisenberg model, demonstrating the existence of short-range FM order in the amorphous alloy ribbons.

  10. Influence of retardation effects on photodisintegration of a quantum system bound by short-range forces

    International Nuclear Information System (INIS)

    Preobrazhenskii, M.A.; Golovinskii, P.A.

    1996-01-01

    Expressions for cross sections for multiphonon disintegration of quantum systems bound by short-range forces are obtained in the plane-wave approximation taking into account retardation effects. It is shown that, in the region of nonrelativistic energies, their contribution is factored, and the resulting universal factor is expressed for an arbitrary degree of process nonlinearity n in terms of elementary functions. Arguments of functions are determined only by the mode ω, the radiation spectrum width β, and the bound-state energy of a system. The dependence of the contribution of retardation effects on ω, β, and n is studied in detail. Analytical expressions for cross sections for multiquantum disintegration in the first nonvanishing order with respect to correlation interaction, which exactly take into account retardation effects, are obtained. It is shown that for two-quantum processes, the contribution of correlation effects is expressed in terms of a function representing an extension of dipole polarizability, whereas for n>2, it can be described in the dipole approximation

  11. Demonstration of micro-projection enabled short-range communication system for 5G.

    Science.gov (United States)

    Chou, Hsi-Hsir; Tsai, Cheng-Yu

    2016-06-13

    A liquid crystal on silicon (LCoS) based polarization modulated image (PMI) system architecture using red-, green- and blue-based light-emitting diodes (LEDs), which offers simultaneous micro-projection and high-speed data transmission at nearly a gigabit, serving as an alternative short-range communication (SRC) approach for personal communication device (PCD) application in 5G, is proposed and experimentally demonstrated. In order to make the proposed system architecture transparent to the future possible wireless data modulation format, baseband modulation schemes such as multilevel pulse amplitude modulation (M-PAM), M-ary phase shift keying modulation (M-PSK) and M-ary quadrature amplitude modulation (M-QAM) which can be further employed by more advanced multicarrier modulation schemes (such as DMT, OFDM and CAP) were used to investigate the highest possible data transmission rate of the proposed system architecture. The results demonstrated that an aggregative data transmission rate of 892 Mb/s and 900 Mb/s at a BER of 10^(-3) can be achieved by using 16-QAM baseband modulation scheme when data transmission were performed with and without micro-projection simultaneously.

  12. Structural study of liquids with strong short-range correlation in the atomic distribution

    International Nuclear Information System (INIS)

    Uzuki, Kenji

    1976-01-01

    Structure factors of liquids and amorphous solids having a relatively high degree of ordering in their short-range structures have been measured over a wide range of scattering vectors by means of the T-O-F neutron diffraction using epithermal pulsed neutrons generated by an electron linear accelerator. It has been shown in the case of liquid CS 2 that the size and shape of a molecule existing in the liquid phase are determined from the behaviour of the structure factor in the range of high scattering vectors, and that the structure factor in the region of low scattering vectors informs on inter-molecular orientational and center-center correlations in the liquid state. Moreover, based on highly resoluted radial distribution functions, a free rotating chain model has been discussed for chain molecules contained in liquid Se, and a splitting of the nearest neighbour Pd-Pd and Pd-Si correlation has been clearly found in the amorphous Pdsub(0.8) - Sisub(0.2) alloy. (orig./HK) [de

  13. 2D fluorescence spectra measurement of six kinds of bioagents simulants by short range Lidar

    Science.gov (United States)

    Sanpedro, Man

    2018-02-01

    Pantoea agglomerans (Pan), Staphylococcus aureus (Sta), Bacillus globigii (BG) and Escherichia coli (EH), these four kinds of bioagents simulants of were cultured and then their growth curves were measured, the generation time was 0.99h, 0.835h, 1.07h and 1.909h, respectively. A small short range fluorescence lidar working at wavelengths of 266nm and 355nm was designed and used to measure the two-dimensional fluorescence spectra of bioagents simulants in the amino acid segment and NADH segment, respectively. In a controllable fluorescence measurement chamber, the two-dimensional fluorescence spectra of vegetative liquid bacterial aerosols as well as BSA and OVA, two protein toxinic simulants were measured with a resolution of 4nm. The two-dimensional fluorescence spectral shape of Pan, Sta, EH and BG, BSA and OVA were consistent with the standard fluorescent component tryptophan in the amino acid band with FWHM of 60nm, but the central wavelength of the fluorescence spectra of these simulants blue/purple shifted obviously as affected by the external biochemical environment, concentration and ratio of different bacterial internal fluorophores, so the energy level between the excited state and the ground state of the fluorescence molecule increased. Differently, weak NADH fluorescence spectra with 100nm FWHM inside the four vegetative bacteria aerosols were detected, but Rayleigh scattering, Raman scattering contribution of water, nitrogen in the fluorescence spectra could not be effectively extracted. The second - order derivative fluorescence spectra of four simulants showed that the high - order processing and recognition of the fluorescence spectra was feasible.

  14. Short-range structure of barium tellurite glasses and its correlation with stress-optic response

    Science.gov (United States)

    Kaur, Amarjot; Khanna, Atul; Fábián, Margit

    2018-06-01

    The atomic parameters of metal ion-oxygen speciation such as bond-lengths and nearest neighbor distances for Ba-O, Te-O and O-O pairs, co-ordination numbers and bond angle distributions for O-Ba-O, O-Te-O and O-O-O linkages are determined by neutron diffraction and Reverse Monte Carlo simulations on the series of xBaO-(100-x)TeO2 glasses containing 10, 15 and 20 mol% BaO. The glass network depolymerizes and the average Te-O co-ordination number decreases from 3.60 ± 0.02 to 3.48 ± 0.02 with increase in BaO concentration. Te-O bond lengths are in the range: 1.97 ± 0.01–1.92 ± 0.01 Å. Ba2+ is mostly in octahedral coordination and the Ba-O bond lengths are in the range: 2.73 ± 0.01 to 2.76 ± 0.03 Å. Te-O co-ordination number is also determined by Raman spectroscopy and it shows good agreement with the neutron data. The short-range structural properties i.e. metal ion coordination number (Nc) and bond lengths (d) were correlated with the stress-optic response. The bonding characteristic, Br values were determined from the structural data of xBaO-(100-x)TeO2 glasses and were used to predict the stress-induced birefringence properties.

  15. Short-range/Long-range Integrated Target (SLIT) for Video Guidance Sensor Rendezvous and Docking

    Science.gov (United States)

    Roe, Fred D. (Inventor); Bryan, Thomas C. (Inventor)

    2009-01-01

    A laser target reflector assembly for mounting upon spacecraft having a long-range reflector array formed from a plurality of unfiltered light reflectors embedded in an array pattern upon a hemispherical reflector disposed upon a mounting plate. The reflector assembly also includes a short-range reflector array positioned upon the mounting body proximate to the long-range reflector array. The short-range reflector array includes three filtered light reflectors positioned upon extensions from the mounting body. The three filtered light reflectors retro-reflect substantially all incident light rays that are transmissive by their monochromatic filters and received by the three filtered light reflectors. In one embodiment the short-range reflector array is embedded within the hemispherical reflector,

  16. Short-range wireless communication fundamentals of RF system design and application

    CERN Document Server

    Bensky, Alan

    2004-01-01

    The Complete "Tool Kit” for the Hottest Area in RF/Wireless Design!Short-range wireless-communications over distances of less than 100 meters-is the most rapidly growing segment of RF/wireless engineering. Alan Bensky is an internationally recognized expert in short-range wireless, and this new edition of his bestselling book is completely revised to cover the latest developments in this fast moving field.You'll find coverage of such cutting-edge topics as: architectural trends in RF/wireless integrated circuits compatibility and conflict issues between differen

  17. The effect of short-range spatial variability on soil sampling uncertainty

    Energy Technology Data Exchange (ETDEWEB)

    Perk, Marcel van der [Department of Physical Geography, Utrecht University, P.O. Box 80115, 3508 TC Utrecht (Netherlands)], E-mail: m.vanderperk@geo.uu.nl; De Zorzi, Paolo; Barbizzi, Sabrina; Belli, Maria [Agenzia per la Protezione dell' Ambiente e per i Servizi Tecnici (APAT), Servizio Laboratori, Misure ed Attivita di Campo, Via di Castel Romano, 100-00128 Roma (Italy); Fajgelj, Ales; Sansone, Umberto [International Atomic Energy Agency (IAEA), Agency' s Laboratories Seibersdorf, A-1400 Vienna (Austria); Jeran, Zvonka; Jacimovic, Radojko [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

    2008-11-15

    This paper aims to quantify the soil sampling uncertainty arising from the short-range spatial variability of elemental concentrations in the topsoils of agricultural, semi-natural, and contaminated environments. For the agricultural site, the relative standard sampling uncertainty ranges between 1% and 5.5%. For the semi-natural area, the sampling uncertainties are 2-4 times larger than in the agricultural area. The contaminated site exhibited significant short-range spatial variability in elemental composition, which resulted in sampling uncertainties of 20-30%.

  18. The effect of short-range spatial variability on soil sampling uncertainty.

    Science.gov (United States)

    Van der Perk, Marcel; de Zorzi, Paolo; Barbizzi, Sabrina; Belli, Maria; Fajgelj, Ales; Sansone, Umberto; Jeran, Zvonka; Jaćimović, Radojko

    2008-11-01

    This paper aims to quantify the soil sampling uncertainty arising from the short-range spatial variability of elemental concentrations in the topsoils of agricultural, semi-natural, and contaminated environments. For the agricultural site, the relative standard sampling uncertainty ranges between 1% and 5.5%. For the semi-natural area, the sampling uncertainties are 2-4 times larger than in the agricultural area. The contaminated site exhibited significant short-range spatial variability in elemental composition, which resulted in sampling uncertainties of 20-30%.

  19. On the Interplay between Order Parameter Dynamics and System Parameter Dynamics in Human Perceptual-Cognitive-Behavioral Systems.

    Science.gov (United States)

    Frank, T D

    2015-04-01

    Previous research has demonstrated that perceiving, thinking, and acting are human activities that correspond to self-organized patterns. The emergence of such patterns can be completely described in terms of the dynamics of the pattern amplitudes, which are referred to as order parameters. The patterns emerge at bifurcations points when certain system parameters internal and external to a human agent exceed critical values. At issue is how one might study the order parameter dynamics for sequences of consecutive, emergent perceptual, cognitive, or behavioral activities. In particular, these activities may in turn impact the system parameters that have led to the emergence of the activities in the first place. This interplay between order parameter dynamics and system parameter dynamics is discussed in general and formulated in mathematical terms. Previous work that has made use of this two-tiered framework of order parameter and system parameter dynamics are briefly addressed. As an application, a model for perception under functional fixedness is presented. Finally, it is argued that the phenomena that emerge in this framework and can be observed when human agents perceive, think, and act are just as likely to occur in pattern formation systems of the inanimate world. Consequently, these phenomena do not necessarily have a neurophysiological basis but should instead be understood from the perspective of the theory of self-organization.

  20. On the universality of the long-/short-range separation in multiconfigurational density-functional theory. II. Investigating f0 actinide species

    DEFF Research Database (Denmark)

    Fromager, Emmanuel; Réal, Florent; Wåhlin, Pernilla

    2009-01-01

    In a previous paper [Fromager , J. Chem. Phys. 126, 074111 (2007)], some of the authors proposed a recipe for choosing the optimal value of the mu parameter that controls the long-range/short-range separation of the two-electron interaction in hybrid multiconfigurational self-consistent field sho...

  1. A universal order parameter for synchrony in networks of limit cycle oscillators

    Science.gov (United States)

    Schröder, Malte; Timme, Marc; Witthaut, Dirk

    2017-07-01

    We analyze the properties of order parameters measuring synchronization and phase locking in complex oscillator networks. First, we review network order parameters previously introduced and reveal several shortcomings: none of the introduced order parameters capture all transitions from incoherence over phase locking to full synchrony for arbitrary, finite networks. We then introduce an alternative, universal order parameter that accurately tracks the degree of partial phase locking and synchronization, adapting the traditional definition to account for the network topology and its influence on the phase coherence of the oscillators. We rigorously prove that this order parameter is strictly monotonously increasing with the coupling strength in the phase locked state, directly reflecting the dynamic stability of the network. Furthermore, it indicates the onset of full phase locking by a diverging slope at the critical coupling strength. The order parameter may find applications across systems where different types of synchrony are possible, including biological networks and power grids.

  2. Linear Parameter Varying Versus Linear Time Invariant Reduced Order Controller Design of Turboprop Aircraft Dynamics

    Directory of Open Access Journals (Sweden)

    Widowati

    2012-07-01

    Full Text Available The applicability of parameter varying reduced order controllers to aircraft model is proposed. The generalization of the balanced singular perturbation method of linear time invariant (LTI system is used to reduce the order of linear parameter varying (LPV system. Based on the reduced order model the low-order LPV controller is designed by using synthesis technique. The performance of the reduced order controller is examined by applying it to lateral-directional control of aircraft model having 20th order. Furthermore, the time responses of the closed loop system with reduced order LPV controllers and reduced order LTI controller is compared. From the simulation results, the 8th order LPV controller can maintain stability and to provide the same level of closed-loop systems performance as the full-order LPV controller. It is different with the reduced-order LTI controller that cannot maintain stability and performance for all allowable parameter trajectories.

  3. Constituent Order in Minimalist Syntax, Universals and Parameters. (VP-Specifier and VP-Complement Order

    Directory of Open Access Journals (Sweden)

    Rachid Bouziane

    2017-01-01

    Full Text Available Natural Languages adopt a variety of structural strategies and architectures in ordering syntactic constituents. We will try in this paper to explain how these strategies and architectures are explained within the Minimalist Program framework. According to this framework, the most significant parametric differences between natural languages in constituent word order are widely and strongly limited to lexical differences. They are specifically attributed to the N-features and V-features of lexical items that occupy the functional category nodes, basically elements belonging to the functional categories Agreement and Tense: “The N-features are those that are checked off against a DP in [Spec, AGRP] (or, potentially, [Spec, TP]”, and “the V-features are those that are checked off against a V that adjoins to a functional head”.

  4. Two-Order-Parameter Description of Liquids: Critical Phenomena and Phase Separation of Supercooled Liquids

    OpenAIRE

    Tanaka, Hajime

    1997-01-01

    Because of the isotropic and disordered nature of liquids, the anisotropy hidden in intermolecular interactions are often neglected. Accordingly, the order parameter describing a simple liquid has so far been believed to be only density. In contrast to this common sense, we propose that two order parameters, namely, density and bond order parameters, are required to describe the phase behavior of liquids since they intrinsically tend to form local bonds. This model gives us clear physical exp...

  5. Functional framework and hardware platform for dependability study in short range wireless embedded systems

    NARCIS (Netherlands)

    Senouci, B.; Annema, Anne J.; Bentum, Marinus Jan; Kerkhoff, Hans G.

    2011-01-01

    A new direction in short-range wireless applications has appeared in the form of high-speed data communication devices for distances of a few meters. Behind these embedded applications, a complex Hardware/Software architecture is built. Dependability is one of the major challenges in these systems.

  6. Short-range clustering and decomposition in copper-nickel and copper-nickel-iron alloys

    International Nuclear Information System (INIS)

    Aalders, T.J.A.

    1982-07-01

    The thermodynamic equilibrium state of short-range clustering and the kinetics of short-range clustering and decomposition has been studied for a number of CuNi(Fe)-alloys by means of neutron scattering. The validity of the theories, which are usually applied to describe spinodal decomposition, nucleation and growth, coarsening etc., was investigated. It was shown that for the investigated substances the conventional theory of spinodal decomposition is valid for the relaxation of short-range clustering only for the case that the initial and final states do not differ too much. The dynamical scaling procedure described by Lebowitz et al. did not lead to a time-independent scaled function F(x) for the relaxation of short-range clustering, for the early stages of decomposition and for the case that an alloy, which was already decomposed at the quench temperature T 1 , was annealed at a temperature T 2 (T 1 ). For the later stages of decomposition, however, the scaling procedure was indeed successful. The coarsening of the alloys could, except for the later stages, be described by the Lifshitz-Slyozov theory. (Auth.)

  7. Status of the dedicated short-range communications technology and applications : report to Congress.

    Science.gov (United States)

    2015-07-01

    This report responds to a Congressional request for an assessment of the 5.9 Gigahertz (GHz) Dedicated Short Range : Communications (DSRC) in accordance with the requirements provided by Congress in the Moving Ahead for Progress in the : 21st Century...

  8. Electronically driven short-range lattice instability: Possible role in superconductive pairing

    International Nuclear Information System (INIS)

    Szasz, A.

    1991-01-01

    A superconducting pairing mechanism is suggested, mediating by collective and coherent cluster fluctuations in the materials. The model, based on a geometrical frustration, proposes a dynamic effect driven by a special short-range electronic instability. Experimental support for this model is discussed

  9. Investigations of multiphoton excitation and ionization in a short range potential

    International Nuclear Information System (INIS)

    Susskind, S.M.; Cowley, S.C.; Valeo, E.J.

    1989-02-01

    We introduce an approach to the study of excitation and ionization for a system with a short range potential. In particular, analytical and numerical results are presented for the multiphoton ionization rate, under strong field conditions, of an electron confined by a δ-function potential. 9 refs., 3 figs

  10. Investigations of multiphoton excitation and ionization in a short range potential

    Energy Technology Data Exchange (ETDEWEB)

    Susskind, S.M.; Cowley, S.C.; Valeo, E.J.

    1989-02-01

    We introduce an approach to the study of excitation and ionization for a system with a short range potential. In particular, analytical and numerical results are presented for the multiphoton ionization rate, under strong field conditions, of an electron confined by a delta-function potential. 9 refs., 3 figs.

  11. Fluid–fluid coexistence in colloidal systems with short-ranged strongly directional attraction

    NARCIS (Netherlands)

    Kern, N.; Frenkel, D.

    2003-01-01

    We present a systematic numerical study of the phase behavior of square-well fluids with a "patchy" short-ranged attraction. In particular, we study the effect of the size and number of attractive patches on the fluid–fluid coexistence. The model that we use is a generalization of the hard sphere

  12. Order parameters and synchronization of FitzHugh–Nagumo small-world networks

    International Nuclear Information System (INIS)

    Yan-Long, Li; Jun, Ma; Yan-Jun, Liu; Wei, Zhang

    2009-01-01

    This paper numerically investigates the order parameter and synchronisation in the small world connected FitzHugh–Nagumo excitable systems. The simulations show that the order parameter continuously decreases with increasing D, the quality of the synchronisation worsens for large noise intensity. As the coupling intensity goes up, the quality of the synchronisation worsens, and it finds that the larger rewiring probability becomes the larger order parameter. It obtains the complete phase diagram for a wide range of values of noise intensity D and control parameter g. (cross-disciplinary physics and related areas of science and technology)

  13. Variances as order parameter and complexity measure for random Boolean networks

    International Nuclear Information System (INIS)

    Luque, Bartolo; Ballesteros, Fernando J; Fernandez, Manuel

    2005-01-01

    Several order parameters have been considered to predict and characterize the transition between ordered and disordered phases in random Boolean networks, such as the Hamming distance between replicas or the stable core, which have been successfully used. In this work, we propose a natural and clear new order parameter: the temporal variance. We compute its value analytically and compare it with the results of numerical experiments. Finally, we propose a complexity measure based on the compromise between temporal and spatial variances. This new order parameter and its related complexity measure can be easily applied to other complex systems

  14. Variances as order parameter and complexity measure for random Boolean networks

    Energy Technology Data Exchange (ETDEWEB)

    Luque, Bartolo [Departamento de Matematica Aplicada y EstadIstica, Escuela Superior de Ingenieros Aeronauticos, Universidad Politecnica de Madrid, Plaza Cardenal Cisneros 3, Madrid 28040 (Spain); Ballesteros, Fernando J [Observatori Astronomic, Universitat de Valencia, Ed. Instituts d' Investigacio, Pol. La Coma s/n, E-46980 Paterna, Valencia (Spain); Fernandez, Manuel [Departamento de Matematica Aplicada y EstadIstica, Escuela Superior de Ingenieros Aeronauticos, Universidad Politecnica de Madrid, Plaza Cardenal Cisneros 3, Madrid 28040 (Spain)

    2005-02-04

    Several order parameters have been considered to predict and characterize the transition between ordered and disordered phases in random Boolean networks, such as the Hamming distance between replicas or the stable core, which have been successfully used. In this work, we propose a natural and clear new order parameter: the temporal variance. We compute its value analytically and compare it with the results of numerical experiments. Finally, we propose a complexity measure based on the compromise between temporal and spatial variances. This new order parameter and its related complexity measure can be easily applied to other complex systems.

  15. Ultra-low-power and ultra-low-cost short-range wireless receivers in nanoscale CMOS

    CERN Document Server

    Lin, Zhicheng; Martins, Rui Paulo

    2016-01-01

    This book provides readers with a description of state-of-the-art techniques to be used for ultra-low-power (ULP) and ultra-low-cost (ULC), short-range wireless receivers. Readers will learn what is required to deploy these receivers in short-range wireless sensor networks, which are proliferating widely to serve the internet of things (IoT) for “smart cities.” The authors address key challenges involved with the technology and the typical tradeoffs between ULP and ULC. Three design examples with advanced circuit techniques are described in order to address these trade-offs, which specially focus on cost minimization. These three techniques enable respectively, cascading of radio frequency (RF) and baseband (BB) circuits under an ultra-low-voltage (ULV) supply, cascoding of RF and BB circuits in current domain for current reuse, and a novel function-reuse receiver architecture, suitable for ULV and multi-band ULP applications such as the sub-GHz ZigBee. ·         Summarizes the state-of-the-art i...

  16. Short-range correlations control the G/K and Poisson ratios of amorphous solids and metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zaccone, Alessio; Terentjev, Eugene M. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

    2014-01-21

    The bulk modulus of many amorphous materials, such as metallic glasses, behaves nearly in agreement with the assumption of affine deformation, namely that the atoms are displaced just by the amount prescribed by the applied strain. In contrast, the shear modulus behaves as for nonaffine deformations, with additional displacements due to the structural disorder which induce a marked material softening to shear. The consequence is an anomalously large ratio of the bulk modulus to the shear modulus for disordered materials characterized by dense atomic packing, but not for random networks with point atoms. We explain this phenomenon with a microscopic derivation of the elastic moduli of amorphous solids accounting for the interplay of nonaffinity and short-range particle correlations due to excluded volume. Short-range order is responsible for a reduction of the nonaffinity which is much stronger under compression, where the geometric coupling between nonaffinity and the deformation field is strong, whilst under shear this coupling is weak. Predictions of the Poisson ratio based on this model allow us to rationalize the trends as a function of coordination and atomic packing observed with many amorphous materials.

  17. Characterizing short-range vs. long-range spatial correlations in dislocation distributions

    Energy Technology Data Exchange (ETDEWEB)

    Chevy, Juliette, E-mail: juliette.chevy@gmail.com [Laboratoire de Glaciologie et Geophysique de l' Environnement-CNRS, 54 rue Moliere, 38402 St. Martin d' Heres (France)] [Laboratoire Science et Ingenierie des Materiaux et Procedes, Grenoble INP-CNRS-UJF, BP 75, 38402 St. Martin d' Heres Cedex (France); Fressengeas, Claude; Lebyodkin, Mikhail; Taupin, Vincent [Laboratoire de Physique et Mecanique des Materiaux, Universite Paul Verlaine-Metz/CNRS, Ile du Saulcy, 57045 Metz Cedex (France); Bastie, Pierre [Laboratoire de Spectrometrie Physique, BP 87, 38402 St. Martin d' Heres Cedex (France)] [Institut Laue Langevin, BP 156, 38042 Grenoble Cedex 9 (France); Duval, Paul [Laboratoire de Glaciologie et Geophysique de l' Environnement-CNRS, 54 rue Moliere, 38402 St. Martin d' Heres (France)

    2010-03-15

    Hard X-ray diffraction experiments have provided evidence of a strongly heterogeneous distribution of dislocation densities along the axis of cylindrical ice single crystals oriented for basal slip in torsion creep. The dislocation arrangements showed a complex scale-invariant character, which was analyzed by means of statistical and multifractal techniques. A trend to decreasing autocorrelation of the dislocation distribution was observed as deformation proceeds. At low strain levels, long-range spatial correlations control the distribution, but short-range correlations in relation with cross-slip progressively prevail when strain increases. This trend was reproduced by a model based on field dislocation dynamics, a theory accounting for both long-range elastic interactions and short-range interactions through transport of dislocation densities.

  18. Characterizing short-range vs. long-range spatial correlations in dislocation distributions

    International Nuclear Information System (INIS)

    Chevy, Juliette; Fressengeas, Claude; Lebyodkin, Mikhail; Taupin, Vincent; Bastie, Pierre; Duval, Paul

    2010-01-01

    Hard X-ray diffraction experiments have provided evidence of a strongly heterogeneous distribution of dislocation densities along the axis of cylindrical ice single crystals oriented for basal slip in torsion creep. The dislocation arrangements showed a complex scale-invariant character, which was analyzed by means of statistical and multifractal techniques. A trend to decreasing autocorrelation of the dislocation distribution was observed as deformation proceeds. At low strain levels, long-range spatial correlations control the distribution, but short-range correlations in relation with cross-slip progressively prevail when strain increases. This trend was reproduced by a model based on field dislocation dynamics, a theory accounting for both long-range elastic interactions and short-range interactions through transport of dislocation densities.

  19. The short range effective interaction and the spectra of calcium isotopes in (f-p) space

    International Nuclear Information System (INIS)

    Qing-ying, Z.; Shen-wu, L.; Jian-xin, W.

    1986-01-01

    In this work, the authors use a new type of extremely short range interaction, the double delta interaction (DDI) to calculate the low-lying spectra of calcium isotopes /sup 41/Ca through /sup 48/Ca. The configuration space (f-p) includes configurations ( f/sub 7/2//sup n/ ) and ( f/sub 7/2//sup n-1/2p/sub 3/2/). The calculated energies are compared with experimental data for 75 levels. For comparison, they also use usual modified surface delta interaction (MSDI) to calculate the same spectra aforementioned. It is clear that the results calculated with DDI are better than with MSDI. Therefore, in the short-range effective interaction the addition of body delta force to the modified surface delta force may improve the agreement with experiment. The authors believe that the conclusion will not be changed if one enlarges the shell model space

  20. Attractive short-range interatomic potential in the lattice dynamics of niobium and tantalum

    International Nuclear Information System (INIS)

    Onwuagba, B.N.; Pal, S.

    1987-01-01

    It is shown in the framework of the pseudopotential approach that there is a sizable attractive short-range component of the interatomic potential due to the s-d interaction which has the same functional form in real space as the Born-Mayer repulsion due to the overlap of core electron wave functions centred on neighbouring ions. The magnitude of this attractive component is such as to completely cancel the conventional Born-Mayer repulsion, making the resultant short-range interatomic potential attractive rather than repulsive. Numerical calculations show that the attractive interatomics potential, which represents the local-field correction, leads to a better understanding of the occurrence of the soft modes in the phonon dispersion curves of niobium and tantalum

  1. Short-Range Noncontact Sensors for Healthcare and Other Emerging Applications: A Review

    Directory of Open Access Journals (Sweden)

    Changzhan Gu

    2016-07-01

    Full Text Available Short-range noncontact sensors are capable of remotely detecting the precise movements of the subjects or wirelessly estimating the distance from the sensor to the subject. They find wide applications in our day lives such as noncontact vital sign detection of heart beat and respiration, sleep monitoring, occupancy sensing, and gesture sensing. In recent years, short-range noncontact sensors are attracting more and more efforts from both academia and industry due to their vast applications. Compared to other radar architectures such as pulse radar and frequency-modulated continuous-wave (FMCW radar, Doppler radar is gaining more popularity in terms of system integration and low-power operation. This paper reviews the recent technical advances in Doppler radars for healthcare applications, including system hardware improvement, digital signal processing, and chip integration. This paper also discusses the hybrid FMCW-interferometry radars and the emerging applications and the future trends.

  2. Neutrino-Nucleus Interactions and the Short-Range Structure of Nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Cavanna, F. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Palamara, O. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Schiavilla, R. [Old Dominion Univ., Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Soderberg, M. [Syracuse Univ., NY (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Wiringa, R. B. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-01-08

    Improvements in theoretical modeling of Short Range structures and phenomena, and comparisons with data, will require sustained collaboration between nuclear theorists and neutrino experimentalists. The extensive history of studying this area of nuclear physics in electron- and hadron-scattering experiments, coupled with the transformative capabilities of LArTPCs to identify neutrinos, will provide a ripe opportunity for new discoveries that will further our understanding of the nucleus.

  3. Probing the short range behavior of nuclei with high PT photo- and electro-nuclear reactions

    International Nuclear Information System (INIS)

    Laget, J.M.

    1990-01-01

    The short range behavior of the nucleus and the use of the nucleus as a filter are studied. Special emphasis is given to photon and hadron induced reactions. The components of the nuclear wave function are described. The evidences of hard scattering processes in reactions induced by real photons as well as by hadrons on free nucleus are reviewed. The spin observables are also investigated. The perspectives opened by these studies in the nuclear environment are considered

  4. Particle simulation algorithms with short-range forces in MHD and fluid flow

    International Nuclear Information System (INIS)

    Cable, S.; Tajima, T.; Umegaki, K.

    1992-07-01

    Attempts are made to develop numerical algorithms for handling fluid flows involving liquids and liquid-gas mixtures. In these types of systems, the short-range intermolecular interactions are important enough to significantly alter behavior predicted on the basis of standard fluid mechanics and magnetohydrodynamics alone. We have constructed a particle-in-cell (PIC) code for the purpose of studying the effects of these interactions. Of the algorithms considered, the one which has been successfully implemented is based on a MHD particle code developed by Brunel et al. In the version presented here, short range forces are included in particle motion by, first, calculating the forces between individual particles and then, to prevent aliasing, interpolating these forces to the computational grid points, then interpolating the forces back to the particles. The code has been used to model a simple two-fluid Rayleigh-Taylor instability. Limitations to the accuracy of the code exist at short wavelengths, where the effects of the short-range forces would be expected to be most pronounced

  5. Angular correlation between short-range. cap alpha. particles and. gamma. quanta

    Energy Technology Data Exchange (ETDEWEB)

    Kul' chitskii, L A; Latyshev, G D; Bulyginskii, D G

    1949-01-01

    Chang (Phys. Rev. 69, 60(1946); 70, 632(1946)) has found that the intensities of short-range ..cap alpha.. rays of Po and Ra are considerably higher than the values given by the Geiger-Nuttall law. This can be explained by assuming surface vibrations of ..cap alpha..-radioactive nuclei, which produce deformations and corresponding lowerings of the potential barrier in certain directions. In this case an angular correlation should exist between the short-range ..cap alpha.. ray and the accompanying ..gamma.. quantum. The authors checked this conclusion by applying the coincidence method to the ..cap alpha.. and ..gamma.. radiations of a mixture of RdTh (/sup 228/Th) and ThC (/sup 212/Bi). Maxima of coincidence numbers occur at angles 45 and 135 deg., with lesser maxima at 0 and 180 deg. Theoretical considerations show that in cases (like the one investigated) where the nuclear spin before and after the ..cap alpha.. and ..gamma.. emissions is zero, the angular correlations are uniquely determined whatever the deformation caused by the vibration; in other cases, the correlation depends on the kind of deformation. Therefore, it would be interesting to investigate the case of Pa, whose nuclear spin is not zero and the decay exhibits intensive groups of short-range ..cap alpha.. particles.

  6. Parameters and Fractional Differentiation Orders Estimation for Linear Continuous-Time Non-Commensurate Fractional Order Systems

    KAUST Repository

    Belkhatir, Zehor; Laleg-Kirati, Taous-Meriem

    2017-01-01

    This paper proposes a two-stage estimation algorithm to solve the problem of joint estimation of the parameters and the fractional differentiation orders of a linear continuous-time fractional system with non-commensurate orders. The proposed algorithm combines the modulating functions and the first-order Newton methods. Sufficient conditions ensuring the convergence of the method are provided. An error analysis in the discrete case is performed. Moreover, the method is extended to the joint estimation of smooth unknown input and fractional differentiation orders. The performance of the proposed approach is illustrated with different numerical examples. Furthermore, a potential application of the algorithm is proposed which consists in the estimation of the differentiation orders of a fractional neurovascular model along with the neural activity considered as input for this model.

  7. Parameters and Fractional Differentiation Orders Estimation for Linear Continuous-Time Non-Commensurate Fractional Order Systems

    KAUST Repository

    Belkhatir, Zehor

    2017-05-31

    This paper proposes a two-stage estimation algorithm to solve the problem of joint estimation of the parameters and the fractional differentiation orders of a linear continuous-time fractional system with non-commensurate orders. The proposed algorithm combines the modulating functions and the first-order Newton methods. Sufficient conditions ensuring the convergence of the method are provided. An error analysis in the discrete case is performed. Moreover, the method is extended to the joint estimation of smooth unknown input and fractional differentiation orders. The performance of the proposed approach is illustrated with different numerical examples. Furthermore, a potential application of the algorithm is proposed which consists in the estimation of the differentiation orders of a fractional neurovascular model along with the neural activity considered as input for this model.

  8. Competition between crystallization and glassification for particles with short-ranged attraction. Possible applications to protein crystallization

    Science.gov (United States)

    Zaccarelli, E.; Sciortino, F.; Tartaglia, P.; Foffi, G.; McCullagh, G. D.; Lawlor, A.; Dawson, K. A.

    2002-11-01

    We discuss the phase behaviour of spherical hard-core particles, with an attractive potential, as described by a hard-core Yukawa model. The ratio of the range of the attraction to the diameter of the particles is an important control parameter of the problem. Upon decreasing the range of the attraction, the phase diagram changes quite significantly, with the liquid-gas transition becoming metastable, and the crystal being in equilibrium with the fluid, with no intervening liquid. We also study the glass transition lines and, crucially, find that the situation, being very simple for pure repulsive potentials, becomes much richer in competition between glass and crystal phases for short-range attractions. Also a transition between attractive and repulsive glass appears somewhat in analogy with the isostructural equilibrium transition between two crystals.

  9. Quasiclassical description of multi-band superconductors with two order parameters

    Energy Technology Data Exchange (ETDEWEB)

    Moor, Andreas

    2014-05-19

    This Thesis deals with multi-band superconductors with two order parameters, i.e., the superconductivity and the spin-density wave, also touching on one-band superconductors with a charge-density wave, as well as with only the superconducting order parameter. Quasiclassical description of suchlike structures is developed and applied to investigation of various effects, inter alia, the Josephson and the proximity effects, the Knight shift, the Larkin-Ovchinnikov-Fulde-Ferrell-like state, and the interplay of the order parameters in coexistence regime. The applicability of the developed approach to pnictides is discussed.

  10. Order parameter fluctuations at a critical point - an exact result about percolation -

    International Nuclear Information System (INIS)

    Botet, Robert

    2011-01-01

    The order parameter of the system in the critical state, is expected to undergo large non-Gaussian fluctuations. However, almost nothing is known about the mathematical forms of the possible probability distributions of the order parameter. A remarkable exception is the site-percolation on the Bethe lattice, for which the complete order-parameter distribution has been recently derived at the critical point. Surprisingly, it appears to be the Kolmogorov-Smirnov distribution, well known in very different areas of mathematical statistics. In the present paper, we explain first how this special distribution could appear naturally in the context of the critical systems, under the assumption (still virtually unstudied) of the exponential distribution of the number of domains of a given size. In a second part, we present for the first time the complete derivation of the order-parameter distribution for the critical percolation model on the Bethe lattice, thus completing a recent publication announcing this result.

  11. Random textures of the order parameter of superfluid sup 3 He-B in aerogel

    CERN Document Server

    Fomin, Yu A

    2002-01-01

    The scheme for describing the properties of the superfluid sup 3 He in the aerogel is proposed in accordance with the Ginzburg and Landau theory. The aerogel effect on the order parameter is described by the random tensor field. This field exerts desorientation effect on the order parameter in the sup 3 He A-phase, but it does not influence the order parameter orientation in the B-phase, if there is no magnetic field. The change in the order parameter texture, originating in the B-phase in the aerogel in the magnetic field, is considered. Fluctuations of the sup 3 He-B anisotropy axis direction are correlated on the length, inversely proportional to the field intensity and having the macroscopic scale

  12. Coupling of order parameters, chirality, and interfacial structures in multiferroic materials.

    Science.gov (United States)

    Conti, Sergio; Müller, Stefan; Poliakovsky, Arkady; Salje, Ekhard K H

    2011-04-13

    We study optimal interfacial structures in multiferroic materials with a biquadratic coupling between two order parameters. We discover a new duality relation between the strong coupling and the weak coupling regime for the case of isotropic gradient terms. We analyze the phase diagram depending on the coupling constant and anisotropy of the gradient term, and show that in a certain regime the secondary order parameter becomes activated only in the interfacial region.

  13. Magnetic phase transitions with incommensurate structures in systems with coupled order parameters

    International Nuclear Information System (INIS)

    Izyumov, Yu.A.; Laptev, V.M.; Petrov, S.B.

    1984-01-01

    Modulated magnetic phases are investigated for the case when symmetry does not allow linear by gradients Lifshits invariants and magnetic momenta are converted by two irreducible representations. Possible phase diagrams with participation of incommensurable phases are plotted on the base of Ginsburg-Landau functional for 2 bound parameters of the order. The role of the highest harmonics in spatial distribution of the order parameters is clarified on the example of magnetic phase transitions in Er

  14. Highly excited bound-state resonances of short-range inverse power-law potentials

    Energy Technology Data Exchange (ETDEWEB)

    Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Academic College, Jerusalem (Israel)

    2017-11-15

    We study analytically the radial Schroedinger equation with long-range attractive potentials whose asymptotic behaviors are dominated by inverse power-law tails of the form V(r) = -β{sub n}r{sup -n} with n > 2. In particular, assuming that the effective radial potential is characterized by a short-range infinitely repulsive core of radius R, we derive a compact analytical formula for the threshold energy E{sub l}{sup max} = E{sub l}{sup max}(n, β{sub n}, R), which characterizes the most weakly bound-state resonance (the most excited energy level) of the quantum system. (orig.)

  15. OTDM Networking for Short Range High-Capacity Highly Dynamic Networks

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros

    This PhD thesis aims at investigating the possibility of designing energy-efficient high-capacity (up to Tbit/s) optical network scenarios, leveraging on the effect of collective switching of many bits simultaneously, as is inherent in high bit rate serial optical data signals. The focus...... is on short range highly dynamic networks, catering to data center needs. The investigation concerns optical network scenarios, and experimental implementations of high bit rate serial data packet generation and reception, scalable optical packet labeling, simple optical label extraction and stable ultra...

  16. The Spectrum of Particles with Short-Ranged Interactions in a Harmonic Trap

    Directory of Open Access Journals (Sweden)

    Metsch B. Ch.

    2010-04-01

    Full Text Available The possibility to control short-ranged interactions of cold gases in optical traps by Feshbachresonances makes these systems ideal candidates to study universal scaling properties and Efimov physics. The spectrum of particles in a trap, idealised by a harmonic oscillator potential, in the zero range limit with 2- and 3-particle contact interactions is studied numerically. The Hamiltonian is regularised by restricting the oscillator basis and the coupling constants are tuned such that the ground state energies of the 2- and 3-particle sector are reproduced [1],[2]. Results for 2-, 3-, and 4 particle systems are presented and compared to exact results [3],[4].

  17. Study of the short-range 3He structure from the dd→3Hen reaction

    International Nuclear Information System (INIS)

    Ladygin, V.P.; Ladygina, N.V.

    1995-01-01

    An experiment on studying of the tensor analysing power C 0,NN,0,0 and spin correlation C N,N,0,0 due to the transverse polarization of both initial particles from the dd→ 3 Hen reaction has been proposed. Those polarization observables are very sensitive to the short-range 3 He structure. This experiment is proposed to be done at the LHE Accelerator Complex using both a polarized deuteron beam and a polarized deuterium target. 25 refs., 2 figs

  18. Measurement based scenario analysis of short-range distribution system planning

    DEFF Research Database (Denmark)

    Chen, Peiyuan; Bak-Jensen, Birgitte; Chen, Zhe

    2009-01-01

    This paper focuses on short-range distribution system planning using a probabilistic approach. Empirical probabilistic distributions of load demand and distributed generations are derived from the historical measurement data and incorporated into the system planning. Simulations with various...... feasible scenarios are performed based on a local distribution system at Støvring in Denmark. Simulation results provide more accurate and insightful information for the decision-maker when using the probabilistic analysis than using the worst-case analysis, so that a better planning can be achieved....

  19. Numerical study of the glass-glass transition in short-ranged attractive colloids

    International Nuclear Information System (INIS)

    Zaccarelli, Emanuela; Sciortino, Francesco; Tartaglia, Piero

    2004-01-01

    We report extensive numerical simulations in the glass region for a simple model of short-ranged attractive colloids, the square well model. We investigate the behaviour of the density autocorrelation function and of the static structure factor in the region of temperatures and packing fractions where a glass-glass transition is expected according to theoretical predictions. We strengthen our observations by studying both waiting time and history dependence of the numerical results. We provide evidence supporting the possibility that activated bond-breaking processes destabilize the attractive glass, preventing the full observation of a sharp glass-glass kinetic transition

  20. Short Range Correlations in Nuclei at Large xbj through Inclusive Quasi-Elastic Electron Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Zhihong [Univ. of Virginia, Charlottesville, VA (United States)

    2013-12-01

    The experiment, E08-014, in Hall-A at Jefferson Lab aims to study the short-range correlations (SRC) which are necessary to explain the nuclear strength absent in the mean field theory. The cross sections for 2H, 3He, 4He, 12C, 40Ca and 48Ca, were measured via inclusive quasi-elastic electron scattering from these nuclei in a Q2 range between 0.8 and 2.8 (GeV/c)2 for x>1. The cross section ratios of heavy nuclei to 2H were extracted to study two-nucleon SRC for 1

  1. Characteristics of III-nitride based laser diode employed for short range underwater wireless optical communications

    Science.gov (United States)

    Xue, Bin; Liu, Zhe; Yang, Jie; Feng, Liangsen; Zhang, Ning; Wang, Junxi; Li, Jinmin

    2018-03-01

    An off-the-shelf green laser diode (LD) was measured to investigate its temperature dependent characteristics. Performance of the device was severely restricted by rising temperature in terms of increasing threshold current and decreasing modulation bandwidth. The observation reveals that dynamic characteristics of the LD is sensitive to temperature. Influence of light attenuation on the modulation bandwidth of the green LD was also studied. The impact of light attenuation on the modulation bandwidth of the LD in short and low turbid water channel was not obvious while slight difference in modulation bandwidth under same injection level was observed between water channel and free space even at short range.

  2. Spin-fluctuation mechanism of high-Tc superconductivity and order-parameter symmetry

    International Nuclear Information System (INIS)

    Izyumov, Yurii A

    1999-01-01

    The notion that electrons in high-T c cuprates pair via antiferromagnetic spin fluctuations is discussed and the symmetry of the superconducting order parameter is analyzed. Three approaches to the problem, one phenomenological (with an experimental dynamic magnetic susceptibility) and two microscopic (involving, respectively, the Hubbard model and the tJ-model) are considered and it is shown that in each case strong-coupling theory leads to a d-wave order parameter with zeros at the Fermi surface. The review then proceeds to consider experimental techniques in which the d-symmetry of the order parameter may manifest itself. These include low-temperature thermodynamic measurements, measurements of the penetration depth and the upper critical field, Josephson junction experiments to obtain the phase of the superconducting order parameter, and various spectroscopic methods. The experimental data suggest that the order parameter in cuprates is d x 2 -y 2 -wave. Ginzburg-Landau theory for a superconductor with a d-wave order parameter is outlined and both an isolated vortex and a vortex lattice are investigated. Finally, some theoretical aspects of the effects of nonmagnetic impurities on a d-wave superconductor are considered. (reviews of topical problems)

  3. Effects of temperature and electric field on order parameters in ferroelectric hexagonal manganites

    Science.gov (United States)

    Zhang, C. X.; Yang, K. L.; Jia, P.; Lin, H. L.; Li, C. F.; Lin, L.; Yan, Z. B.; Liu, J.-M.

    2018-03-01

    In Landau-Devonshire phase transition theory, the order parameter represents a unique property for a disorder-order transition at the critical temperature. Nevertheless, for a phase transition with more than one order parameter, such behaviors can be quite different and system-dependent in many cases. In this work, we investigate the temperature (T) and electric field (E) dependence of the two order parameters in improper ferroelectric hexagonal manganites, addressing the phase transition from the high-symmetry P63/mmc structure to the polar P63cm structure. It is revealed that the trimerization as the primary order parameter with two components: the trimerization amplitude Q and phase Φ, and the spontaneous polarization P emerging as the secondary order parameter exhibit quite different stability behaviors against various T and E. The critical exponents for the two parameters Q and P are 1/2 and 3/2, respectively. As temperature increases, the window for the electric field E enduring the trimerization state will shrink. An electric field will break the Z2 part of the Z2×Z3 symmetry. The present work may shed light on the complexity of the vortex-antivortex domain structure evolution near the phase transition temperature.

  4. Order parameters in lanthanum gallate lightly doped with manganese and paramagnetic resonance

    Science.gov (United States)

    Vazhenin, V. A.; Potapov, A. P.; Artyomov, M. Yu.; Guseva, V. B.

    2010-09-01

    The Cr3+ centers have been revealed, transitions at room temperature have been identified, and spin Hamiltonian parameters have been determined for the Cr3+ and Fe3+ triclinic centers in lanthanum gallate lightly doped with manganese. The principal axes of the fourth-rank fine-structure tensor for the Fe3+ triclinic centers have been established and used to determine the order parameters, i.e., the angles of rotation of oxygen octahedra of lanthanum gallate with respect to the perovskite structure. The order parameter in the rhombohedral phase has been estimated.

  5. Self-assembled fluids with order-parameter-dependent mobility: The ...

    Indian Academy of Sciences (India)

    The study is for quenching from an uncorrelated high temperature state into the Lifshitz line within the microemulsion phase. In the later stage of the ordering process, the structure factor exhibits multiscaling behavior with characteristic length scale (/ ln )1/2(2+3). The order-parameter-dependent mobility is found to slow ...

  6. BAYESIAN PARAMETER ESTIMATION IN A MIXED-ORDER MODEL OF BOD DECAY. (U915590)

    Science.gov (United States)

    We describe a generalized version of the BOD decay model in which the reaction is allowed to assume an order other than one. This is accomplished by making the exponent on BOD concentration a free parameter to be determined by the data. This "mixed-order" model may be ...

  7. Short-range contacts govern the performance of industry-relevant battery cathodes

    Science.gov (United States)

    Morelly, Samantha L.; Alvarez, Nicolas J.; Tang, Maureen H.

    2018-05-01

    Fundamental understanding of how processing affects composite battery electrode structure and performance is still lacking, especially for industry-relevant electrodes with low fractions of inactive material. This work combines rheology, electronic conductivity measurements, and battery rate capability tests to prove that short-range electronic contacts are more important to cathode rate capability than either ion transport or long-range electronic conductivity. LiNi0.33Mn0.33Co0.33O2, carbon black, and polyvinylidene difluoride in 1-methyl-2-pyrrolidinone represent a typical commercial electrode with films. Improvements in battery rate capability at constant electrode porosity do not correlate to electronic conductivity, but rather show an optimum fraction of free carbon. Simple comparison of rate capability in electrodes with increased total carbon loading (3 wt%) shows improvement for all fractions of free carbon. These results clearly indicate that ion transport cannot be limiting and highlight the critical importance of short-range electronic contacts for controlling battery performance.

  8. CMOS Receiver Front-ends for Gigabit Short-Range Optical Communications

    CERN Document Server

    Aznar, Francisco; Calvo Lopez, Belén

    2013-01-01

    This book describes optical receiver solutions integrated in standard CMOS technology, attaining high-speed short-range transmission within cost-effective constraints.  These techniques support short reach applications, such as local area networks, fiber-to-the-home and multimedia systems in cars and homes. The authors show how to implement the optical front-end in the same technology as the subsequent digital circuitry, leading to integration of the entire receiver system in the same chip.  The presentation focuses on CMOS receiver design targeting gigabit transmission along a low-cost, standardized plastic optical fiber up to 50m in length.  This book includes a detailed study of CMOS optical receiver design – from building blocks to the system level. Reviews optical communications, including long-haul transmission systems and emerging applications focused on short-range; Explains necessary fundamentals, such as characteristics of a data signal, system requirements affecting receiver design and key par...

  9. Short range part of the NN interaction: Equivalent local potentials from quark exchange kernels

    International Nuclear Information System (INIS)

    Suzuk, Y.; Hecht, K.T.

    1983-01-01

    To focus on the nature of the short range part of the NN interaction, the intrinsically nonlocal interaction among the quark constituents of colorless nucleons is converted to an equivalent local potential using resonating group kernels which can be evaluated in analytic form. The WKB approximation based on the Wigner transform of the nonlocal kernels has been used to construct the equivalent potentials without recourse to the long range part of the NN interaction. The relative importance of the various components of the exchange kernels can be examined: The results indicate the importance of the color magnetic part of the exchange kernel for the repulsive part in the (ST) = (10), (01) channels, in particular since the energy dependence of the effective local potentials seems to be set by this term. Large cancellations of color Coulombic and quark confining contributions, together with the kinetic energy and norm exchange terms, indicate that the exact nature of the equivalent local potential may be sensitive to the details of the parametrization of the underlying quark-quark interaction. The equivalent local potentials show some of the characteristics of the phenomenological short range terms of the Paris potential

  10. Implementing Molecular Dynamics for Hybrid High Performance Computers - 1. Short Range Forces

    International Nuclear Information System (INIS)

    Brown, W. Michael; Wang, Peng; Plimpton, Steven J.; Tharrington, Arnold N.

    2011-01-01

    The use of accelerators such as general-purpose graphics processing units (GPGPUs) have become popular in scientific computing applications due to their low cost, impressive floating-point capabilities, high memory bandwidth, and low electrical power requirements. Hybrid high performance computers, machines with more than one type of floating-point processor, are now becoming more prevalent due to these advantages. In this work, we discuss several important issues in porting a large molecular dynamics code for use on parallel hybrid machines - (1) choosing a hybrid parallel decomposition that works on central processing units (CPUs) with distributed memory and accelerator cores with shared memory, (2) minimizing the amount of code that must be ported for efficient acceleration, (3) utilizing the available processing power from both many-core CPUs and accelerators, and (4) choosing a programming model for acceleration. We present our solution to each of these issues for short-range force calculation in the molecular dynamics package LAMMPS. We describe algorithms for efficient short range force calculation on hybrid high performance machines. We describe a new approach for dynamic load balancing of work between CPU and accelerator cores. We describe the Geryon library that allows a single code to compile with both CUDA and OpenCL for use on a variety of accelerators. Finally, we present results on a parallel test cluster containing 32 Fermi GPGPUs and 180 CPU cores.

  11. Analysis of deuterium relaxation-derived methyl axis order parameters and correlation with local structure

    International Nuclear Information System (INIS)

    Mittermaier, Anthony; Kay, Lewis E.; Forman-Kay, Julie D.

    1999-01-01

    Methyl axis (S2axis) and backbone NH (S2NH) order parameters derived from eight proteins have been analyzed. Similar distribution profiles for Ala S2axis and S2NH order parameters were observed. A good correlation between the two S2axis values of Val and Leu methyl groups is noted, although differences between order parameters can arise. The relation of S2axis or S2NH to solvent accessibility and packing density has also been investigated. Correlations are weak, likely reflecting the importance of collective, non-local motions in proteins. The lack of correlation between these simple structural parameters and dynamics emphasizes the importance of motional studies to fully characterize proteins

  12. Evidence for short range corelations from high Q2 (e,e') reactions

    International Nuclear Information System (INIS)

    Strikman, M.I.; Frankfurt, L.L.; Sargayan, M.M.

    1994-01-01

    For many years now short-range correlations (SRC) in nuclei have been considered as an essential feature of the nuclear wave function. At high energy (e,e') reactions, where Q 2 > 1 (GeV/c) 2 , x = Q 2 /2mq o > 1 and 1 GeV > q o > 300 ∼ 400 MeV the scattering from low momentum nucleons is kinematically suppressed and there the evidence of SRC expected to be more prominent. These reactions have been intensively investigated during the last decade or so at SLAC on both light and heavy nuclei. The above kinematics allows one to compute the cross section through the processes local in space. To explain this the authors analyse the representation of the cross section as a Fourier transform of the commutator of electromagnetic currents and see that the major contribution in the cross section is given by the region of integration

  13. Improving Short-Range Ensemble Kalman Storm Surge Forecasting Using Robust Adaptive Inflation

    KAUST Repository

    Altaf, Muhammad

    2013-08-01

    This paper presents a robust ensemble filtering methodology for storm surge forecasting based on the singular evolutive interpolated Kalman (SEIK) filter, which has been implemented in the framework of the H∞ filter. By design, an H∞ filter is more robust than the common Kalman filter in the sense that the estimation error in the H∞ filter has, in general, a finite growth rate with respect to the uncertainties in assimilation. The computational hydrodynamical model used in this study is the Advanced Circulation (ADCIRC) model. The authors assimilate data obtained from Hurricanes Katrina and Ike as test cases. The results clearly show that the H∞-based SEIK filter provides more accurate short-range forecasts of storm surge compared to recently reported data assimilation results resulting from the standard SEIK filter.

  14. Mass dependence of short-range correlations in nuclei and the EMC effect

    Directory of Open Access Journals (Sweden)

    Cosyn Wim

    2014-03-01

    Full Text Available We sketch an approximate method to quantify the number of correlated pairs in any nucleus A. It is based on counting independent-particle model (IPM nucleon-nucleon pairs in a relative S-state with no radial excitation. We show that IPM pairs with those quantum numbers are most prone to short-range correlations and are at the origin of the high-momentum tail of the nuclear momentum distributions. Our method allows to compute the a2 ratios extracted from inclusive electron scattering. Furthermore, our results reproduce the observed linear correlation between the number of correlated pairs and the magnitude of the EMC effect. We show that the width of the pair center-ofmass distribution in exclusive two-nucleon knockout yields information on the quantum numbers of the pairs.

  15. Short-Range Electron Transfer in Reduced Flavodoxin: Ultrafast Nonequilibrium Dynamics Coupled with Protein Fluctuations.

    Science.gov (United States)

    Kundu, Mainak; He, Ting-Fang; Lu, Yangyi; Wang, Lijuan; Zhong, Dongping

    2018-05-03

    Short-range electron transfer (ET) in proteins is an ultrafast process on the similar timescales as local protein-solvent fluctuations thus the two dynamics are coupled. Here, we use semiquinone flavodoxin and systematically characterized the photoinduced redox cycle with eleven mutations of different aromatic electron donors (tryptophan and tyrosine) and local residues to change redox properties. We observed the forward and backward ET dynamics in a few picoseconds, strongly following a stretched behavior resulting from a coupling between local environment relaxations and these ET processes. We further observed the hot vibrational-state formation through charge recombination and the subsequent cooling dynamics also in a few picoseconds. Combined with the ET studies in oxidized flavodoxin, these results coherently reveal the evolution of the ET dynamics from single to stretched exponential behaviors and thus elucidate critical timescales for the coupling. The observed hot vibration-state formation is robust and should be considered in all photoinduced back ET processes in flavoproteins.

  16. The dependence of the nuclear charge form factor on short range correlations and surface fluctuation effects

    International Nuclear Information System (INIS)

    Massen, S. E.; Garistov, V. P.; Grypeos, M. E.

    1996-01-01

    The effects of nuclear surface fluctuations on harmonic oscillator elastic charge form factor of light nuclei are investigated, simultaneously approximating the short-range correlations through a Jastrow correlation factor. Inclusion of the surface fluctuation effects within this description, by truncating the cluster expansion at the two-body part, is found to improve somewhat the fit to the elastic charge form-factor of 16 O and 40 Ca. However, the convergence of the cluster expansion is expected to deteriorate. An additional finding is that surface-fluctuation correlations produce a drastic change in the asymptotic behaviour of the point-proton form-factor, which now falls off quite slowly (i.e. as const.q -4 ) at large values of the momentum transfer q

  17. Age differences in visual search for compound patterns: long- versus short-range grouping.

    Science.gov (United States)

    Burack, J A; Enns, J T; Iarocci, G; Randolph, B

    2000-11-01

    Visual search for compound patterns was examined in observers aged 6, 8, 10, and 22 years. The main question was whether age-related improvement in search rate (response time slope over number of items) was different for patterns defined by short- versus long-range spatial relations. Perceptual access to each type of relation was varied by using elements of same contrast (easy to access) or mixed contrast (hard to access). The results showed large improvements with age in search rate for long-range targets; search rate for short-range targets was fairly constant across age. This pattern held regardless of whether perceptual access to a target was easy or hard, supporting the hypothesis that different processes are involved in perceptual grouping at these two levels. The results also point to important links between ontogenic and microgenic change in perception (H. Werner, 1948, 1957).

  18. Structure factor of polymers interacting via a short range repulsive potential: Application to hairy wormlike micelles

    International Nuclear Information System (INIS)

    Massiera, Gladys; Ramos, Laurence; Ligoure, Christian; Pitard, Estelle

    2003-01-01

    We use the random phase approximation to compute the structure factor S(q) of a solution of chains interacting through a soft and short range repulsive potential V. Above a threshold polymer concentration, whose magnitude is essentially controlled by the range of the potential, S(q) exhibits a peak whose position depends on the concentration. We take advantage of the close analogy between polymers and wormlike micelles and apply our model, using a Gaussian function for V, to quantitatively analyze experimental small angle neutron scattering profiles of solutions of hairy wormlike micelles. These samples, which consist in surfactant self-assembled flexible cylinders decorated by amphiphilic copolymer, provide indeed an appropriate experimental model system to study the structure of sterically interacting polymer solutions

  19. A New Theoretical Analysis of the Effects of Short Range Correlations in Inclusive Lepton Scattering

    Science.gov (United States)

    Benedetta Mezzetti, Chiara; Ciofi Degli Atti, Claudio

    2009-05-01

    Recently, evidence of short range correlations (SRC) has been provided by experimental data on inclusive lepton A(e, e')X scattering by the observation of a scaling behavior of the ratios of the cross sections on heavy nuclei to those on the deuteron and ^3He. Other attempts to get information on SRC rely on the concept of Y-scaling, whose interest has been renewed by new Jlab data. A new approach to Y-scaling, relying on the definition of a new relativistic scaling variable which incorporates the momentum dependence of the excitation energy of the (A - 1) system is presented, with the resulting scaling function being closely related to the longitudinal momentum distributions. Taking into account final state interaction effects, the new analysis of experimental data on nuclei, ranging from ^3He to Nuclear Matter, provides unique information on the nucleon momentum distributions and confirms the analysis in terms of cross section ratios.

  20. Controlling Short-Range Interactions by Tuning Surface Chemistry in HDPE/Graphene Nanoribbon Nanocomposites.

    Science.gov (United States)

    Sadeghi, Soheil; Zehtab Yazdi, Alireza; Sundararaj, Uttandaraman

    2015-09-03

    Unique dispersion states of nanoparticles in polymeric matrices have the potential to create composites with enhanced mechanical, thermal, and electrical properties. The present work aims to determine the state of dispersion from the melt-state rheological behavior of nanocomposites based on carbon nanotube and graphene nanoribbon (GNR) nanomaterials. GNRs were synthesized from nitrogen-doped carbon nanotubes via a chemical route using potassium permanganate and some second acids. High-density polyethylene (HDPE)/GNR nanocomposite samples were then prepared through a solution mixing procedure. Different nanocomposite dispersion states were achieved using different GNR synthesis methods providing different surface chemistry, interparticle interactions, and internal compartments. Prolonged relaxation of flow induced molecular orientation was observed due to the presence of both carbon nanotubes and GNRs. Based on the results of this work, due to relatively weak interactions between the polymer and the nanofillers, it is expected that short-range interactions between nanofillers play the key role in the final dispersion state.

  1. Short-range structure and thermal properties of lead tellurite glasses

    Science.gov (United States)

    Hirdesh, Kaur, Amarjot; Khanna, Atul; Gonzàlez, Fernando

    2017-05-01

    PbO-TeO2 glasses having composition: xPbO-(100 - x)TeO2 (x = 10, 15 and 20 mol%) were prepared by melt quenching and characterized by X-ray diffraction, density measurements, differential scanning calorimetry and Raman spectroscopy. Glass density increases from 5.89 to 6.22 g cm-3 with increase in PbO concentration from 10 to 20 mol%, due to the replacement of TeO2 by heavier PbO. DSC studies found that glass transition temperature (Tg) decreases from a value of 295°C to 281°C. Raman studies found that glass short-range structure consists of TeO4 and TeO3 structural units and that PbO modifies the network by the structural transformation: TeO4 to TeO3.

  2. Short-range structure and thermal properties of barium tellurite glasses

    Science.gov (United States)

    Kaur, Amarjot; Khanna, Atul; Gonzàlez, Fernando

    2017-05-01

    BaO-TeO2 glasses containing 10 to 20 BaO mol% were prepared and characterized by X-ray diffraction, density measurements, differential scanning calorimetry and Raman spectroscopy. Glass density decreases with increase in BaO concentration from 10 to 20 mol%, due to replacement of heavier TeO2 by lighter BaO, however glass transition temperature (Tg) increases significantly from a value of 318°C to 327°C due to increase in average single bond enthalpy of the tellurite network. Raman studies found that glass short-range structure consists of TeO4 and TeO3 structural units and BaO modifies the network by producing the structural transformation: TeO4→ TeO3.

  3. Polarizable embedding with a multiconfiguration short-range density functional theory linear response method

    DEFF Research Database (Denmark)

    Hedegård, Erik D.; Olsen, Jógvan Magnus Haugaard; Knecht, Stefan

    2015-01-01

    . To demonstrate the capabilities of PE-MC-srDFT, we also investigated the retinylidene Schiff base chromophore embedded in the channelrhodopsin protein. While using a much more compact reference wave function in terms of active space, our PE-MC-srDFT approach yields excitation energies comparable in quality......We present here the coupling of a polarizable embedding (PE) model to the recently developed multiconfiguration short-range density functional theory method (MC-srDFT), which can treat multiconfigurational systems with a simultaneous account for dynamical and static correlation effects. PE......-MC-srDFT is designed to combine efficient treatment of complicated electronic structures with inclusion of effects from the surrounding environment. The environmental effects encompass classical electrostatic interactions as well as polarization of both the quantum region and the environment. Using response theory...

  4. Improving Short-Range Ensemble Kalman Storm Surge Forecasting Using Robust Adaptive Inflation

    KAUST Repository

    Altaf, Muhammad; Butler, T.; Luo, X.; Dawson, C.; Mayo, T.; Hoteit, Ibrahim

    2013-01-01

    This paper presents a robust ensemble filtering methodology for storm surge forecasting based on the singular evolutive interpolated Kalman (SEIK) filter, which has been implemented in the framework of the H∞ filter. By design, an H∞ filter is more robust than the common Kalman filter in the sense that the estimation error in the H∞ filter has, in general, a finite growth rate with respect to the uncertainties in assimilation. The computational hydrodynamical model used in this study is the Advanced Circulation (ADCIRC) model. The authors assimilate data obtained from Hurricanes Katrina and Ike as test cases. The results clearly show that the H∞-based SEIK filter provides more accurate short-range forecasts of storm surge compared to recently reported data assimilation results resulting from the standard SEIK filter.

  5. Utilizing Context in Location-Aware Short-Range Wireless Communication

    Directory of Open Access Journals (Sweden)

    Vesa A. Korhonen

    2010-01-01

    Full Text Available We discuss how a short-range wireless communication service implemented for modern mobile communication devices can provide additional value for both the consumer and the service/product provider. When used as an information search tool, such systems allow services and products being promoted at the location they are available. For the customer, it may provide a “digitally augmented vision”, an enhanced view to the current environment. With data filtering and search rules, this may provide a self-manageable context, where the user's own personal environment and preferences to the features available in the current surroundings cooperate with a direct connection to the web-based social media. A preliminary design for such service is provided. The conclusion is that the method can generate additional revenue to the company and please the customers' buying process. In addition to the marketing, the principles described here are also applicable to other forms of human interaction.

  6. 79 GHz UWB automotive short range radar – Spectrum allocation and technology trends

    Directory of Open Access Journals (Sweden)

    H.-L. Bloecher

    2009-05-01

    Full Text Available Automotive UWB (Ultra-Wideband short range radar (SSR is on the market as a key technology for novel comfort and safety systems. SiGe based 79 GHz UWB SRR will be a definite candidate for the long term substitution of the 24 GHz UWB SRR. This paper will give an overview of the finished BMBF joint project KOKON and the recently started successing project RoCC, which concentrate on the development of this technology and sensor demonstrators. In both projects, the responsibilities of Daimler AG deal with application based sensor specification, test and evaluation of realized sensor demonstrators. Recent UWB SRR frequency regulation approaches and activitites will be introduced. Furthermore, some first results of Daimler activities within RoCC will be presented, dealing with the packaging and operation of these sensors within the complex car environment.

  7. Short-range wakefields generated in the blowout regime of plasma-wakefield acceleration

    Science.gov (United States)

    Stupakov, G.

    2018-04-01

    In the past, calculation of wakefields generated by an electron bunch propagating in a plasma has been carried out in linear approximation, where the plasma perturbation can be assumed small and plasma equations of motion linearized. This approximation breaks down in the blowout regime where a high-density electron driver expels plasma electrons from its path and creates a cavity void of electrons in its wake. In this paper, we develop a technique that allows us to calculate short-range longitudinal and transverse wakes generated by a witness bunch being accelerated inside the cavity. Our results can be used for studies of the beam loading and the hosing instability of the witness bunch in plasma-wakefield and laser-wakefield acceleration.

  8. Multi-channel, passive, short-range anti-aircraft defence system

    Science.gov (United States)

    Gapiński, Daniel; Krzysztofik, Izabela; Koruba, Zbigniew

    2018-01-01

    The paper presents a novel method for tracking several air targets simultaneously. The developed concept concerns a multi-channel, passive, short-range anti-aircraft defence system based on the programmed selection of air targets and an algorithm of simultaneous synchronisation of several modified optical scanning seekers. The above system is supposed to facilitate simultaneous firing of several self-guided infrared rocket missiles at many different air targets. From the available information, it appears that, currently, there are no passive self-guided seekers that fulfil such tasks. This paper contains theoretical discussions and simulations of simultaneous detection and tracking of many air targets by mutually integrated seekers of several rocket missiles. The results of computer simulation research have been presented in a graphical form.

  9. An Empirical Path-Loss Model for Wireless Channels in Indoor Short-Range Office Environment

    Directory of Open Access Journals (Sweden)

    Ye Wang

    2012-01-01

    Full Text Available A novel empirical path-loss model for wireless indoor short-range office environment at 4.3–7.3 GHz band is presented. The model is developed based on the experimental datum sampled in 30 office rooms in both line of sight (LOS and non-LOS (NLOS scenarios. The model is characterized as the path loss to distance with a Gaussian random variable X due to the shadow fading by using linear regression. The path-loss exponent n is fitted by the frequency using power function and modeled as a frequency-dependent Gaussian variable as the standard deviation σ of X. The presented works should be available for the research of wireless channel characteristics under universal indoor short-distance environments in the Internet of Things (IOT.

  10. n-p Short-Range Correlations from (p,2p+n) Measurements

    Science.gov (United States)

    Tang, A.; Watson, J. W.; Aclander, J.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Gushue, S.; Heppelmann, S.; Leksanov, A.; Makdisi, Y.; Malki, A.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Yu.; Piasetzky, E.; Schetkovsky, A.; Shimanskiy, S.; Zhalov, D.

    2003-01-01

    We studied the 12C(p,2p+n) reaction at beam momenta of 5.9, 8.0, and 9.0 GeV/c. For quasielastic (p,2p) events pf, the momentum of the knocked-out proton before the reaction, was compared (event by event) with pn, the coincident neutron momentum. For |pn|>kF=0.220 GeV/c (the Fermi momentum) a strong back-to-back directional correlation between pf and pn was observed, indicative of short-range n-p correlations. From pn and pf we constructed the distributions of c.m. and relative motion in the longitudinal direction for correlated pairs. We also determined that 49±13% of events with |pf|>kF had directionally correlated neutrons with |pn|>kF.

  11. HQET at order 1/m. Pt. 1. Non-perturbative parameters in the quenched approximation

    Energy Technology Data Exchange (ETDEWEB)

    Blossier, Benoit [Paris XI Univ., 91 - Orsay (France). Lab. de Physique Theorique; Della Morte, Michele [Mainz Univ. (Germany). Inst. fuer Kernphysik; Garron, Nicolas [Universidad Autonoma de Madrid (Spain). Dept. Fisica Teorica y Inst. de Fisica Teorica UAM/CSIC; Edinburgh Univ. (United Kingdom). School of Physics and Astronomy - SUPA; Sommer, Rainer [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC

    2010-01-15

    We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of heavy-light axial-vector and vector currents in the quenched approximation. The HQET expansion includes terms of order 1/m{sub b}. Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m{sub b} in HQET. The determination of the parameters is separated into universal and non-universal parts. The universal results can be used to determine the parameters for various discretizations. The computation reported in this paper uses the plaquette gauge action and the ''HYP1/2'' action for the b-quark described by HQET. The parameters of the currents also depend on the light-quark action, for which we choose non-perturbatively O(a)-improved Wilson fermions. (orig.)

  12. HQET at order 1/m. Pt. 1. Non-perturbative parameters in the quenched approximation

    International Nuclear Information System (INIS)

    Blossier, Benoit; Della Morte, Michele; Garron, Nicolas; Edinburgh Univ.; Sommer, Rainer

    2010-01-01

    We determine non-perturbatively the parameters of the lattice HQET Lagrangian and those of heavy-light axial-vector and vector currents in the quenched approximation. The HQET expansion includes terms of order 1/m b . Our results allow to compute, for example, the heavy-light spectrum and B-meson decay constants in the static approximation and to order 1/m b in HQET. The determination of the parameters is separated into universal and non-universal parts. The universal results can be used to determine the parameters for various discretizations. The computation reported in this paper uses the plaquette gauge action and the ''HYP1/2'' action for the b-quark described by HQET. The parameters of the currents also depend on the light-quark action, for which we choose non-perturbatively O(a)-improved Wilson fermions. (orig.)

  13. Searching for Short Range Correlations Using (e,e'NN) Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bin [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2003-02-01

    Electron induced two nucleon knockout reactions (e,e'pp) and (e,e'np) were performed for 3He, 4He, and 12C nuclei with incident energies of 2.261 GeV and 4.461 GeV using the CLAS detector at Jefferson Lab. Events with missing momenta lower than the Fermi level and missing energies smaller than the pion threshold were studied. The residual system was assumed to be a spectator and the process was considered as a quasi-free knockout of an NN pair. The data showed that the initial momentum extends up to 800 MeV/c with considerable strength. The cross sections for 3He(e,e'pp)n were compared to the calculations of J.M. Laget. It was found that the final state interactions (FSI) and the meson exchange currents (MEC) dominate the cross sections and the short range properties of the NN pair were substantially undermined. However, the node of the S state wave function of the pp pair at around 400 MeV/c initial momentum starts to be recognizable in the 4.461 GeV data. The data and the theory suggest that with higher momentum transfers, especially in the region xBj > 1, the competing processes such as FSI and MEC will be less important and the detailed study of the short-range properties of nucleons inside nuclei will be more desirable.

  14. NMR determination of the order parameter in proton and deuteron glasses

    International Nuclear Information System (INIS)

    Blinc, R.; Dolinsek, J.; Zalar, B.

    1989-01-01

    The inhomogeneous broadening of the ND + deuteron, O-D--O deuteron and 87 Rb quadrapole perturbed NMR spectra in Rb 0.56 (ND 4 ) 0.44 D 2 PO 4 is used for a direct determination of the Edwards-Anderson pseudo-spin glass order parameter. The data provide strong support for a model where the basic difference between magnetic spin glasses and proton or deuteron glasses is the presence of an inherent random field resulting from substitutional disorder which linearly couples to the O-D--O pseudo spins. In these systems we do not deal with a transition from a paraelectric to a pseudo-spin glass phase but rather with a transition from an ergodic pseudo-spin glass phase with a single order parameter q to a non-ergodic pseudo-spin glass phase with an infinite number of order parameters. (author). 11 refs.; 6 figs

  15. Diffusionless phase transition with two order parameters in spin-crossover solids

    Energy Technology Data Exchange (ETDEWEB)

    Gudyma, Iurii, E-mail: yugudyma@gmail.com; Ivashko, Victor [Department of General Physics, Chernivtsi National University, 58012 Chernivtsi (Ukraine); Linares, Jorge [Groupe d' Etude de la Matière Condensée (GEMAC), UMR 8635, CNRS, Université de Versailles Saint Quentin, 45 avenue des Etats-Unis, 78035 Versailles (France)

    2014-11-07

    The quantitative analysis of the interface boundary motion between high-spin and low-spin phases is presented. The nonlinear effect of the switching front rate on the temperature is shown. A compressible model of spin-crossover solid is studied in the framework of the Ising-like model with two-order parameters under statistical approach, where the effect of elastic strain on interaction integral is considered. These considerations led to examination of the relation between the order parameters during temperature changes. Starting from the phenomenological Hamiltonian, entropy has been derived using the mean field approach. Finally, the phase diagram, which characterizes the system, is numerically analyzed.

  16. Ginsburg-Landau theory of two antagonistic order parameters: magnetism and superconductivity

    International Nuclear Information System (INIS)

    Suhl, H.

    1978-01-01

    An attempt is made to construct a Ginsburg-Landau theory of so-called magnetic superconductors. Two order parameters, the magnetization field and the gap function, are introduced in such a way as to inhibit each others growth. It is found that the non-local character of the superconducting order parameter must be taken into account in any evaluation of effects of the critical magnetic fluctuations. Some predictions are made within the limits of Ornstein-Zoernicke-like fluctuation theory and some comparison is made with available data. (Auth.)

  17. Parameter estimation of fractional-order chaotic systems by using quantum parallel particle swarm optimization algorithm.

    Directory of Open Access Journals (Sweden)

    Yu Huang

    Full Text Available Parameter estimation for fractional-order chaotic systems is an important issue in fractional-order chaotic control and synchronization and could be essentially formulated as a multidimensional optimization problem. A novel algorithm called quantum parallel particle swarm optimization (QPPSO is proposed to solve the parameter estimation for fractional-order chaotic systems. The parallel characteristic of quantum computing is used in QPPSO. This characteristic increases the calculation of each generation exponentially. The behavior of particles in quantum space is restrained by the quantum evolution equation, which consists of the current rotation angle, individual optimal quantum rotation angle, and global optimal quantum rotation angle. Numerical simulation based on several typical fractional-order systems and comparisons with some typical existing algorithms show the effectiveness and efficiency of the proposed algorithm.

  18. On the transition from short-range diffusion-limited to collision-limited growth in alloy solidification

    International Nuclear Information System (INIS)

    Aziz, M.J.; Boettinger, W.J.

    1994-01-01

    Short-range diffusion-limited growth, collision-limited growth, and the transition between the two regimes are explained as natural consequences of a single model for the kinetics of alloy solidification. Analytical expressions are developed for the velocity-undercooling function of a planar interface during dilute alloy solidification, using Turnbull's collision-limited growth model and the Continuous Growth Solute Trapping Model of Aziz and Kaplan both with and without a solute drag effect. The interface mobility, -dv/dT, is shown to be very high (proportional to the speed of sound) if the alloy is sufficiently dilute or if the growth rate is sufficiently rapid for nearly complete solute trapping. The interface mobility is reduced by the three orders of magnitude (becoming proportional to the diffusive speed) at intermediate growth rates where partial solute trapping occurs. Differences in low velocity predictions of the models with and without solute drag are also discussed. Comparison of the results of the analytical expressions to numerical solutions of the non-dilute kinetic model for Al-Be alloys shows that the dilute approximation breaks down at melt compositions on the order of 10 at.%. Similar variations in the interface mobility are shown for the disorder-trapping model of Boettinger and Aziz

  19. Quantum correction and ordering parameter for systems connected by a general point canonical transformation

    International Nuclear Information System (INIS)

    Yeon, Kyu Hwang; Hong, Suc Kyoung; Um, Chung In; George, Thomas F.

    2006-01-01

    With quantum operators corresponding to functions of the canonical variables, Schroedinger equations are constructed for systems corresponding to classical systems connected by a general point canonical transformation. Using the operator connecting quantum states between systems before and after the transformation, the quantum correction term and ordering parameter are obtained

  20. Spatial variations of order parameter around Kondo impurity for T<=Tsub(c)

    International Nuclear Information System (INIS)

    Yoksan, S.

    1980-04-01

    Analytic expressions for the spatial variations of the order parameter around a Kondo impurity are obtained. The oscillatory contribution due to the impurity scattering is calculated using the t matrix of Matsuura which conveniently yields the general results below Tsub(c). Differences between our values and those of Schlottmann are reported. (author)

  1. Evaluation of third order nonlinear optical parameters of CdS/PVA nanocomposite

    International Nuclear Information System (INIS)

    Sharma, Mamta; Tripathi, S. K.

    2015-01-01

    CdS nanoparticles dispersed in PVA are prepared by Chemical method at room temperature. The nonlinear optical parameters such as nonlinear absorption (β), nonlinear refractive index (n 2 ) and nonlinear susceptibility (χ 3 ) are calculated for this sample by using Z-scan technique. CdS/PVA samples show the two photon absorption mechanism. The third order nonlinear susceptibility is calculated from n 2 and β and is found to be of the order of 10 −7 – 10 −8 m 2 /V 2 . The larger value of third order nonlinear susceptibility is due to dielectric and quantum confinement effect

  2. Unexpected behavior of an order parameter for lattice gauge theories with matter fields

    International Nuclear Information System (INIS)

    Meyer, H.

    1983-07-01

    I consider a slightly modified definition of an order parameter that was recently suggested by DeTar and McLerran. It is supposed to test for confinement in lattice gauge theories when arbitrary matter fields are present, at finite physical temperature β -1 > 0. Its definition is quite directly related to confinement in the sense that no physical states with fractional baryon number can be observed. We test the parameter for different ranges of the coupling constants in the Z(2) Higgs model, whose phase structure is well known at zero temperature. It is found that the order parameter always shows the behavior characteristic of confinement, for all values of the coupling constants and arbitrary nonzero temperature. (orig.)

  3. Assessing first-order emulator inference for physical parameters in nonlinear mechanistic models

    Science.gov (United States)

    Hooten, Mevin B.; Leeds, William B.; Fiechter, Jerome; Wikle, Christopher K.

    2011-01-01

    We present an approach for estimating physical parameters in nonlinear models that relies on an approximation to the mechanistic model itself for computational efficiency. The proposed methodology is validated and applied in two different modeling scenarios: (a) Simulation and (b) lower trophic level ocean ecosystem model. The approach we develop relies on the ability to predict right singular vectors (resulting from a decomposition of computer model experimental output) based on the computer model input and an experimental set of parameters. Critically, we model the right singular vectors in terms of the model parameters via a nonlinear statistical model. Specifically, we focus our attention on first-order models of these right singular vectors rather than the second-order (covariance) structure.

  4. Order parameters in the Landau–de Gennes theory – the static and dynamic scenarios

    KAUST Repository

    Majumdar, Apala

    2011-01-01

    We obtain quantitative estimates for the scalar order parameters of liquid crystal configurations in three-dimensional geometries, within the Landau-de Gennes framework. We consider both static equilibria and non-equilibrium dynamics and we include external fields and surface anchoring energies in our formulation. Using maximum principle-type arguments, we obtain explicit bounds for the corresponding scalar order parameters in both static and dynamic situations; these bounds are given in terms of the material-dependent thermotropic coefficients, electric field strength and surface anchoring coefficients. These bounds provide estimates for the degree of orientational ordering, quantify the competing effects of the different energetic contributions and can be used to test the accuracy of numerical simulations. © 2011 Taylor & Francis.

  5. Order parameters in the Landau–de Gennes theory – the static and dynamic scenarios

    KAUST Repository

    Majumdar, Apala

    2011-02-17

    We obtain quantitative estimates for the scalar order parameters of liquid crystal configurations in three-dimensional geometries, within the Landau-de Gennes framework. We consider both static equilibria and non-equilibrium dynamics and we include external fields and surface anchoring energies in our formulation. Using maximum principle-type arguments, we obtain explicit bounds for the corresponding scalar order parameters in both static and dynamic situations; these bounds are given in terms of the material-dependent thermotropic coefficients, electric field strength and surface anchoring coefficients. These bounds provide estimates for the degree of orientational ordering, quantify the competing effects of the different energetic contributions and can be used to test the accuracy of numerical simulations. © 2011 Taylor & Francis.

  6. Order-parameter tensor description of HPr in a medium of oriented bicelles.

    Science.gov (United States)

    van Lune, Franciska; Manning, Linda; Dijkstra, Klaas; Berendsen, Herman J C; Scheek, Ruud M

    2002-07-01

    Residual dipolar couplings between 15N and 1H nuclear spins in HPr were used to determine the protein's orientation in a medium of bicelles, oriented by a magnetic field. In the case of wild-type HPr the protein's non-spherical shape can explain its orientation in this medium. In the case of the F48W mutant it was found that at least one other mechanism contributes to the observed orientation of the protein, to a degree that depends on the concentration of phosphate ions in the medium. We propose that the F48W mutant has a weak affinity towards the bicelle-surfaces that decreases with increasing phosphate concentrations. We used an order-parameter description to analyse this situation and to determine the axis of main order and the sign of the order parameter pertaining to this additional orientation mechanism.

  7. Crossover Scaling of Apparent First-order Wetting in Two-dimensional Systems with Short-ranged Forces.

    Czech Academy of Sciences Publication Activity Database

    Parry, A.O.; Malijevský, Alexandr

    2016-01-01

    Roč. 93, č. 6 (2016), s. 062802 ISSN 2470-0045 R&D Projects: GA ČR GA13-09914S Grant - others:EPSRC(GB) EP/L0205641/1 Institutional support: RVO:67985858 Keywords : planar ising ferromagnet * line tension * functional renormalization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.366, year: 2016

  8. The pitfalls of short-range endemism: high vulnerability to ecological and landscape traps

    Directory of Open Access Journals (Sweden)

    Leanda D. Mason

    2018-05-01

    Full Text Available Ecological traps attract biota to low-quality habitats. Landscape traps are zones caught in a vortex of spiralling degradation. Here, we demonstrate how short-range endemic (SRE traits may make such taxa vulnerable to ecological and landscape traps. Three SRE species of mygalomorph spider were used in this study: Idiommata blackwalli, Idiosoma sigillatum and an undescribed Aganippe sp. Mygalomorphs can be long-lived (>43 years and select sites for permanent burrows in their early dispersal phase. Spiderlings from two species, I. blackwalli (n = 20 and Aganippe sp. (n = 50, demonstrated choice for microhabitats under experimental conditions, that correspond to where adults typically occur in situ. An invasive veldt grass microhabitat was selected almost exclusively by spiderlings of I. sigillatum. At present, habitat dominated by veldt grass in Perth, Western Australia, has lower prey diversity and abundance than undisturbed habitats and therefore may act as an ecological trap for this species. Furthermore, as a homogenising force, veldt grass can spread to form a landscape trap in naturally heterogeneous ecosystems. Selection of specialised microhabitats of SREs may explain high extinction rates in old, stable landscapes undergoing (human-induced rapid change.

  9. Evidence for short range corelations from high Q{sup 2} (e,e{prime}) reactions

    Energy Technology Data Exchange (ETDEWEB)

    Strikman, M.I. [Pennsylvania State Univ., University Park, PA (United States); Frankfurt, L.L.; Sargayan, M.M. [Tel Aviv Univ. (Iceland)] [and others

    1994-04-01

    For many years now short-range correlations (SRC) in nuclei have been considered as an essential feature of the nuclear wave function. At high energy (e,e{prime}) reactions, where Q{sup 2} > 1 (GeV/c){sup 2}, x = Q{sup 2}/2mq{sub o} > 1 and 1 GeV > q{sub o}> 300 {approximately} 400 MeV the scattering from low momentum nucleons is kinematically suppressed and there the evidence of SRC expected to be more prominent. These reactions have been intensively investigated during the last decade or so at SLAC on both light and heavy nuclei. The above kinematics allows one to compute the cross section through the processes local in space. To explain this the authors analyse the representation of the cross section as a Fourier transform of the commutator of electromagnetic currents and see that the major contribution in the cross section is given by the region of integration.

  10. On the skill of various ensemble spread estimators for probabilistic short range wind forecasting

    Science.gov (United States)

    Kann, A.

    2012-05-01

    A variety of applications ranging from civil protection associated with severe weather to economical interests are heavily dependent on meteorological information. For example, a precise planning of the energy supply with a high share of renewables requires detailed meteorological information on high temporal and spatial resolution. With respect to wind power, detailed analyses and forecasts of wind speed are of crucial interest for the energy management. Although the applicability and the current skill of state-of-the-art probabilistic short range forecasts has increased during the last years, ensemble systems still show systematic deficiencies which limit its practical use. This paper presents methods to improve the ensemble skill of 10-m wind speed forecasts by combining deterministic information from a nowcasting system on very high horizontal resolution with uncertainty estimates from a limited area ensemble system. It is shown for a one month validation period that a statistical post-processing procedure (a modified non-homogeneous Gaussian regression) adds further skill to the probabilistic forecasts, especially beyond the nowcasting range after +6 h.

  11. Dissipative NEGF methodology to treat short range Coulomb interaction: Current through a 1D nanostructure.

    Science.gov (United States)

    Martinez, Antonio; Barker, John R; Di Prieto, Riccardo

    2018-06-13

    A methodology describing Coulomb blockade in the Non-equilibrium Green Function formalism is presented. We carried out ballistic and dissipative simulations through a 1D quantum dot using an Einstein phonon model. Inelastic phonons with different energies have been considered. The methodology incorporates the short-range Coulomb interaction between two electrons through the use of a two-particle Green's function. Unlike previous work, the quantum dot has spatial resolution i.e. it is not just parameterized by the energy level and coupling constants of the dot. Our method intends to describe the effect of electron localization while maintaining an open boundary or extended wave function. The formalism conserves the current through the nanostructure. A simple 1D model is used to explain the increase of mobility in semi-crystalline polymers as a function of the electron concentration. The mechanism suggested is based on the lifting of energy levels into the transmission window as a result of the local electron-electron repulsion inside a crystalline domain. The results are aligned with recent experimental findings. Finally, as a proof of concept, we present a simulation of a low temperature resonant structure showing the stability diagram in the Coulomb blockade regime. . © 2018 IOP Publishing Ltd.

  12. Current research efforts at JILA to test the equivalence principle at short ranges

    International Nuclear Information System (INIS)

    Faller, J.E.; Niebauer, T.M.; McHugh, M.P.; Van Baak, D.A.

    1988-01-01

    We are presently engaged in three different experiments to search for a possible breakdown of the equivalence principle at short ranges. The first of these experiments, which has been completed, is our so-called Galilean test in which the differential free-fall of two objects of differing composition was measured using laser interferometry. We observed that the differential acceleration of two test bodies was less than 5 parts in 10 billion. This experiment set new limits on a suggested baryon dependent ''Fifth Force'' at ranges longer than 1 km. With a second experiment, we are investigating substance dependent interactions primarily for ranges up to 10 meters using a fluid supported torsion balance; this apparatus has been built and is now undergoing laboratory tests. Finally, a proposal has been made to measure the gravitational signal associated with the changing water level at a large pumped storage facility in Ludington, Michigan. Measuring the gravitational signal above and below the pond will yield the value of the gravitational constant, G, at ranges from 10-100 m. These measurements will serve as an independent check on other geophysical measurements of G

  13. Experimental Searches for Exotic Short-Range Forces Using Mechanical Oscillators

    Science.gov (United States)

    Weisman, Evan

    Experimental searches for forces beyond gravity and electromagnetism at short range have attracted a great deal of attention over the last decade. In this thesis I describe the test mass development for two new experiments searching for forces below 1 mm. Both modify a previous experiment that used 1 kHz mechanical oscillators as test masses with a stiff conducting shield between them to suppress backgrounds, a promising technique for probing exceptionally small distances at the limit of instrumental thermal noise. To further reduce thermal noise, one experiment will use plated silicon test masses at cryogenic temperatures. The other experiment, which searches for spin-dependent interactions, will apply the spin-polarizable material Dy3Fe5O 12 to the test mass surfaces. This material exhibits orbital compensation of the magnetism associated with its intrinsic electron spin, minimizing magnetic backgrounds. Several plated silicon test mass prototypes were fabricated using photolithography (useful in both experiments), and spin-dependent materials were synthesized with a simple chemical recipe. Both silicon and spin-dependent test masses demonstrate the mechanical and magnetic properties necessary for sensitive experiments. I also describe sensitivity calculations of another proposed spin-dependent experiment, based on a modified search for the electron electric dipole moment, which show unprecedented sensitivity to exotic monopole-dipole forces. Inspired by a finite element model, a study attempting to maximize detector quality factor versus geometry is also presented, with experimental results so far not explained by the model.

  14. Meta-heuristic CRPS minimization for the calibration of short-range probabilistic forecasts

    Science.gov (United States)

    Mohammadi, Seyedeh Atefeh; Rahmani, Morteza; Azadi, Majid

    2016-08-01

    This paper deals with the probabilistic short-range temperature forecasts over synoptic meteorological stations across Iran using non-homogeneous Gaussian regression (NGR). NGR creates a Gaussian forecast probability density function (PDF) from the ensemble output. The mean of the normal predictive PDF is a bias-corrected weighted average of the ensemble members and its variance is a linear function of the raw ensemble variance. The coefficients for the mean and variance are estimated by minimizing the continuous ranked probability score (CRPS) during a training period. CRPS is a scoring rule for distributional forecasts. In the paper of Gneiting et al. (Mon Weather Rev 133:1098-1118, 2005), Broyden-Fletcher-Goldfarb-Shanno (BFGS) method is used to minimize the CRPS. Since BFGS is a conventional optimization method with its own limitations, we suggest using the particle swarm optimization (PSO), a robust meta-heuristic method, to minimize the CRPS. The ensemble prediction system used in this study consists of nine different configurations of the weather research and forecasting model for 48-h forecasts of temperature during autumn and winter 2011 and 2012. The probabilistic forecasts were evaluated using several common verification scores including Brier score, attribute diagram and rank histogram. Results show that both BFGS and PSO find the optimal solution and show the same evaluation scores, but PSO can do this with a feasible random first guess and much less computational complexity.

  15. Interplay between short-range correlated disorder and Coulomb interaction in nodal-line semimetals

    Science.gov (United States)

    Wang, Yuxuan; Nandkishore, Rahul M.

    2017-09-01

    In nodal-line semimetals, Coulomb interactions and short-range correlated disorder are both marginal perturbations to the clean noninteracting Hamiltonian. We analyze their interplay using a weak-coupling renormalization group approach. In the clean case, the Coulomb interaction has been found to be marginally irrelevant, leading to Fermi liquid behavior. We extend the analysis to incorporate the effects of disorder. The nodal line structure gives rise to kinematical constraints similar to that for a two-dimensional Fermi surface, which plays a crucial role in the one-loop renormalization of the disorder couplings. For a twofold degenerate nodal loop (Weyl loop), we show that disorder flows to strong coupling along a unique fixed trajectory in the space of symmetry inequivalent disorder couplings. Along this fixed trajectory, all symmetry inequivalent disorder strengths become equal. For a fourfold degenerate nodal loop (Dirac loop), disorder also flows to strong coupling, however, the strengths of symmetry inequivalent disorder couplings remain different. We show that feedback from disorder reverses the sign of the beta function for the Coulomb interaction, causing the Coulomb interaction to flow to strong coupling as well. However, the Coulomb interaction flows to strong coupling asymptotically more slowly than disorder. Extrapolating our results to strong coupling, we conjecture that at low energies nodal line semimetals should be described by a noninteracting nonlinear sigma model. We discuss the relation of our results with possible many-body localization at zero temperatures in such materials.

  16. A UHF RFID system with on-chip-antenna tag for short range communication

    International Nuclear Information System (INIS)

    Peng Qi; Zhang Chun; Zhao Xijin; Wang Zhihua

    2015-01-01

    A UHF RF identification system based on the 0.18 μm CMOS process has been developed for short range and harsh size requirement applications, which is composed of a fully integrated tag and a special reader. The whole tag chip with the antenna takes up an area of 0.36 mm 2 , which is smaller than other reported tags with an on-chip antenna (OCA) using the standard CMOS process. A self-defined protocol is proposed to reduce the power consumption, and minimize the size of the tag. The specialized SOC reader system consists of the RF transceiver, digital baseband, MCU and host interface. Its power consumption is about 500 mW. Measurement results show that the system's reading range is 2 mm with 20 dBm reader output power. With an inductive antenna printed on a paper substrate around the OCA tag, the reading range can be extended from several centimeters to meters, depending on the shape and size of the inductive antenna. (paper)

  17. Measurement of transparency ratios for protons from short-range correlated pairs

    Science.gov (United States)

    Hen, O.; Hakobyan, H.; Shneor, R.; Piasetzky, E.; Weinstein, L. B.; Brooks, W. K.; May-Tal Beck, S.; Gilad, S.; Korover, I.; Beck, A.; Adhikari, K. P.; Aghasyan, M.; Amaryan, M. J.; Anefalos Pereira, S.; Arrington, J. R.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Harrison, N.; Heddle, D.; Hicks, K.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kubarovsky, V.; Kuhn, S. E.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Martinez, D.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Munevar, E.; Munoz Camacho, C.; Mustapha, B.; Nadel-Turonski, P.; Nasseripour, R.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Phelps, E.; Phillips, J. J.; Pisano, S.; Pivnyuk, N.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Schott, D.; Schumacher, R. A.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stepanyan, S.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tian, Ye; Tkachenko, S.; Ungaro, M.; Vernarsky, B.; Vlassov, A.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zheng, X.; Zonta, I.

    2013-05-01

    Nuclear transparency, Tp (A), is a measure of the average probability for a struck proton to escape the nucleus without significant re-interaction. Previously, nuclear transparencies were extracted for quasi-elastic A (e ,e‧ p) knockout of protons with momentum below the Fermi momentum, where the spectral functions are well known. In this Letter we extract a novel observable, the transparency ratio, Tp (A) /Tp(12 C), for knockout of high-missing-momentum protons from the breakup of short-range correlated pairs (2N-SRC) in Al, Fe and Pb nuclei relative to C. The ratios were measured at momentum transfer Q2 ⩾ 1.5(GeV /c) 2 and xB ⩾ 1.2 where the reaction is expected to be dominated by electron scattering from 2N-SRC. The transparency ratios of the knocked-out protons coming from 2N-SRC breakup are 20-30% lower than those of previous results for low missing momentum. They agree with Glauber calculations and agree with renormalization of the previously published transparencies as proposed by recent theoretical investigations. The new transparencies scale as A - 1 / 3, which is consistent with dominance of scattering from nucleons at the nuclear surface.

  18. Quantum saturation of the order parameter and the dynamical soft mode in quartz

    CERN Document Server

    Romero, F J

    2003-01-01

    The temperature evolution of the static order parameter of alpha-quartz and its soft-mode frequencies were determined at temperatures below 300 K. While these parameters follow classic Landau theory at higher temperatures, quantum saturation was found below room temperature with a characteristic quantum temperature of 187 K. A quantitative analysis gave a good agreement with the predictions of a PHI sup 6 model close to the displacive limit and a rather flat dispersion of the soft-mode branch. No indication of any effect of strong mode-mode coupling on the saturation behaviour was observed.

  19. Modulating functions method for parameters estimation in the fifth order KdV equation

    KAUST Repository

    Asiri, Sharefa M.

    2017-07-25

    In this work, the modulating functions method is proposed for estimating coefficients in higher-order nonlinear partial differential equation which is the fifth order Kortewegde Vries (KdV) equation. The proposed method transforms the problem into a system of linear algebraic equations of the unknowns. The statistical properties of the modulating functions solution are described in this paper. In addition, guidelines for choosing the number of modulating functions, which is an important design parameter, are provided. The effectiveness and robustness of the proposed method are shown through numerical simulations in both noise-free and noisy cases.

  20. Magnetic anisotropy and order parameter in nanostructured CoPt particles

    Science.gov (United States)

    Komogortsev, S. V.; Iskhakov, R. S.; Zimin, A. A.; Filatov, E. Yu.; Korenev, S. V.; Shubin, Yu. V.; Chizhik, N. A.; Yurkin, G. Yu.; Eremin, E. V.

    2013-10-01

    The correlation of magnetic anisotropy energy with order parameter in the crystallites of CoPt nanostructured particles prepared by thermal decomposition and further annealing has been studied by investigation of the approach magnetization to saturation curves and x-ray powder diffraction pattern profiles. It is shown that magnetic anisotropy energy value in partially ordered CoPt crystallite could be described as an intermediate case between two extremes, corresponding to either single or several c-domains of L10 phase in crystallite.

  1. Does an electronic continuum correction improve effective short-range ion-ion interactions in aqueous solution?

    Science.gov (United States)

    Bruce, Ellen E.; van der Vegt, Nico F. A.

    2018-06-01

    Non-polarizable force fields for hydrated ions not always accurately describe short-range ion-ion interactions, frequently leading to artificial ion clustering in bulk aqueous solutions. This can be avoided by adjusting the nonbonded anion-cation or cation-water Lennard-Jones parameters. This approach has been successfully applied to different systems, but the parameterization is demanding owing to the necessity of separate investigations of each ion pair. Alternatively, polarization effects may effectively be accounted for using the electronic continuum correction (ECC) of Leontyev et al. [J. Chem. Phys. 119, 8024 (2003)], which involves scaling the ionic charges with the inverse square-root of the water high-frequency dielectric permittivity. ECC has proven to perform well for monovalent salts as well as for divalent salts in water. Its performance, however, for multivalent salts with higher valency remains unexplored. The present work illustrates the applicability of the ECC model to trivalent K3PO4 and divalent K2HPO4 in water. We demonstrate that the ECC models, without additional tuning of force field parameters, provide an accurate description of water-mediated interactions between salt ions. This results in predictions of the osmotic coefficients of aqueous K3PO4 and K2HPO4 solutions in good agreement with experimental data. Analysis of ion pairing thermodynamics in terms of contact ion pair (CIP), solvent-separated ion pair, and double solvent-separated ion pair contributions shows that potassium-phosphate CIP formation is stronger with trivalent than with divalent phosphate ions.

  2. Structural order parameter in the pyrochlore superconductor Cd sub 2 Re sub 2 O sub 7

    CERN Document Server

    Sergienko, I A

    2003-01-01

    It is shown that both structural phase transitions in Cd sub 2 Re sub 2 O sub 7 , which occur at T sub s sub 1 = 200 K and T sub s sub 2 = 120 K, are due to an instability of the Re tetrahedral network with respect to the same doubly degenerate long-wavelength phonon mode. The primary structural order parameter transforms according to the irreducible representation E sub u of the point group O sub h. We argue that the transition at T sub s sub 1 may be of the second order, in accordance with experimental data. We obtain the phase diagram in the space of phenomenological parameters and propose a thermodynamic path that Cd sub 2 Re sub 2 O sub 7 follows upon cooling. Coupling of the itinerant electronic system and localized spin states in pyrochlores and spinels to atomic displacements are discussed. (author)

  3. Effect of a pseudogap on Tc and on the superconducting order parameter

    International Nuclear Information System (INIS)

    Rodriguez Nunez, J.J.; Reimer Romero, J.J.; Valera, M.; Schmidt, A.A.

    2007-09-01

    We further develop the pseudogap model proposed by J.L. Tallon and J.W. Loram, Physica C 349, 53-68 (2001). For the pseudogap order parameter we choose a particular form which reproduces the main features of the high temperature superconductor (HTSC) phase diagram which depends on carrier number, n. For fitting the key features of the cuprate oxides we have sensible parameters at our disposal, namely, α, which fixes the density where the pseudogap order parameter is maximum, α' which allows us to display the T c vs n curve and E go which gives us the value of the pseudogap. We have reproduced in a qualitative fashion the main details of the experimental data given in the work of Suryadijaya, T. Sasaqawa, and H. Takagi, Physica C 426-431, 402-406 (2005). Our main results are the following: To have decreased the value of T c with respect to the 'free' case, namely, E go = 0, namely, when the pseudogap order parameter is not present. To have obtained the maximum of T c by choosing α' ≠ 0. To have chosen the minimum value of T c inside the pseudogap region, namely, in the region where the pseudogap parameter is a maximum. To have bounded the region of the superconducting dome by choosing the value of E g. In short, we have proposed a phenomenological form for the pseudogap energy, which depends on carrier number and which reproduces in a qualitative way the results of Suryadijaya, T. Sasaqawa and H. Takagi, Physica C 426-431, 402-406 (2005). Consequently, we conclude that the pseudogap is necessary for HTSC. (author)

  4. Short-Range Prediction of Monsoon Precipitation by NCMRWF Regional Unified Model with Explicit Convection

    Science.gov (United States)

    Mamgain, Ashu; Rajagopal, E. N.; Mitra, A. K.; Webster, S.

    2018-03-01

    There are increasing efforts towards the prediction of high-impact weather systems and understanding of related dynamical and physical processes. High-resolution numerical model simulations can be used directly to model the impact at fine-scale details. Improvement in forecast accuracy can help in disaster management planning and execution. National Centre for Medium Range Weather Forecasting (NCMRWF) has implemented high-resolution regional unified modeling system with explicit convection embedded within coarser resolution global model with parameterized convection. The models configurations are based on UK Met Office unified seamless modeling system. Recent land use/land cover data (2012-2013) obtained from Indian Space Research Organisation (ISRO) are also used in model simulations. Results based on short-range forecast of both the global and regional models over India for a month indicate that convection-permitting simulations by the high-resolution regional model is able to reduce the dry bias over southern parts of West Coast and monsoon trough zone with more intense rainfall mainly towards northern parts of monsoon trough zone. Regional model with explicit convection has significantly improved the phase of the diurnal cycle of rainfall as compared to the global model. Results from two monsoon depression cases during study period show substantial improvement in details of rainfall pattern. Many categories in rainfall defined for operational forecast purposes by Indian forecasters are also well represented in case of convection-permitting high-resolution simulations. For the statistics of number of days within a range of rain categories between `No-Rain' and `Heavy Rain', the regional model is outperforming the global model in all the ranges. In the very heavy and extremely heavy categories, the regional simulations show overestimation of rainfall days. Global model with parameterized convection have tendency to overestimate the light rainfall days and

  5. Limited-area short-range ensemble predictions targeted for heavy rain in Europe

    Directory of Open Access Journals (Sweden)

    K. Sattler

    2005-01-01

    Full Text Available Inherent uncertainties in short-range quantitative precipitation forecasts (QPF from the high-resolution, limited-area numerical weather prediction model DMI-HIRLAM (LAM are addressed using two different approaches to creating a small ensemble of LAM simulations, with focus on prediction of extreme rainfall events over European river basins. The first ensemble type is designed to represent uncertainty in the atmospheric state of the initial condition and at the lateral LAM boundaries. The global ensemble prediction system (EPS from ECMWF serves as host model to the LAM and provides the state perturbations, from which a small set of significant members is selected. The significance is estimated on the basis of accumulated precipitation over a target area of interest, which contains the river basin(s under consideration. The selected members provide the initial and boundary data for the ensemble integration in the LAM. A second ensemble approach tries to address a portion of the model-inherent uncertainty responsible for errors in the forecasted precipitation field by utilising different parameterisation schemes for condensation and convection in the LAM. Three periods around historical heavy rain events that caused or contributed to disastrous river flooding in Europe are used to study the performance of the LAM ensemble designs. The three cases exhibit different dynamic and synoptic characteristics and provide an indication of the ensemble qualities in different weather situations. Precipitation analyses from the Deutsche Wetterdienst (DWD are used as the verifying reference and a comparison of daily rainfall amounts is referred to the respective river basins of the historical cases.

  6. Short-range and long-range forces in quantum theory: selected topics

    International Nuclear Information System (INIS)

    Hiller, J.R.

    1980-01-01

    Short-range forces (SRF) are encountered when the effects of the parity-violating (PV) weak neutral current are considered in atomic systems. We consider these and other SRF that are associated with operators that contain delta functions. Identities which convert a delta-function matrix element to that of a global operator are reviewed. Past and possible future applications of such identities are described. It has been found that use of these identities can substantially improve the results obtained with less accurate wave functions. We present a further application to the hyperfine structure of the ground state of lithium where we again find that results are improved by the use of an identity. A long-range force (LRF) is here defined to be one that is associated with a potential V(r) that is asymptotically of the form lambda r - 1 (r 0 /r)/sup N-1/. We use a dispersion-theoretic approach to study LRF between hadrons due to two-glucon exchange within the framework of quantum chromodynamics. Such an LRF is usually related to the presence of a spectrum of physical states that extends to zero mass. A speculative scheme put forward by Feinberg and Sucher is used to avoid requiring the existence of massless gluons as observable particles. Semi-quantitative expressions for the two-glucon exchange potential between hadrons and, in particular, between two nucleons are obtained. Limits on two-gluon corrections to πp forward scattering dispersion relations are used to provide an upper bound for lambda, the coupling constant in the nucleon-nucleon potential. For N greater than or equal to 7, expected on heuristic grounds, we obtain the bound lambda less than or equal to 10 6 , which is very weak; gluon effects as treated here do not lead to significant effects in the dispersion-theoretic analysis of πp scattering

  7. Reduced-order modelling of parameter-dependent, linear and nonlinear dynamic partial differential equation models.

    Science.gov (United States)

    Shah, A A; Xing, W W; Triantafyllidis, V

    2017-04-01

    In this paper, we develop reduced-order models for dynamic, parameter-dependent, linear and nonlinear partial differential equations using proper orthogonal decomposition (POD). The main challenges are to accurately and efficiently approximate the POD bases for new parameter values and, in the case of nonlinear problems, to efficiently handle the nonlinear terms. We use a Bayesian nonlinear regression approach to learn the snapshots of the solutions and the nonlinearities for new parameter values. Computational efficiency is ensured by using manifold learning to perform the emulation in a low-dimensional space. The accuracy of the method is demonstrated on a linear and a nonlinear example, with comparisons with a global basis approach.

  8. Generalized dislocated lag function projective synchronization of fractional order chaotic systems with fully uncertain parameters

    International Nuclear Information System (INIS)

    Wang, Cong; Zhang, Hong-li; Fan, Wen-hui

    2017-01-01

    In this paper, we propose a new method to improve the safety of secure communication. This method uses the generalized dislocated lag projective synchronization and function projective synchronization to form a new generalized dislocated lag function projective synchronization. Moreover, this paper takes the examples of fractional order Chen system and Lü system with uncertain parameters as illustration. As the parameters of the two systems are uncertain, the nonlinear controller and parameter update algorithms are designed based on the fractional stability theory and adaptive control method. Moreover, this synchronization form and method of control are applied to secure communication via chaotic masking modulation. Many information signals can be recovered and validated. Finally, simulations are used to show the validity and feasibility of the proposed scheme.

  9. Short-time dynamics of lysozyme solutions with competing short-range attraction and long-range repulsion: Experiment and theory

    Science.gov (United States)

    Riest, Jonas; Nägele, Gerhard; Liu, Yun; Wagner, Norman J.; Godfrin, P. Douglas

    2018-02-01

    Recently, atypical static features of microstructural ordering in low-salinity lysozyme protein solutions have been extensively explored experimentally and explained theoretically based on a short-range attractive plus long-range repulsive (SALR) interaction potential. However, the protein dynamics and the relationship to the atypical SALR structure remain to be demonstrated. Here, the applicability of semi-analytic theoretical methods predicting diffusion properties and viscosity in isotropic particle suspensions to low-salinity lysozyme protein solutions is tested. Using the interaction potential parameters previously obtained from static structure factor measurements, our results of Monte Carlo simulations representing seven experimental lysoyzme samples indicate that they exist either in dispersed fluid or random percolated states. The self-consistent Zerah-Hansen scheme is used to describe the static structure factor, S(q), which is the input to our calculation schemes for the short-time hydrodynamic function, H(q), and the zero-frequency viscosity η. The schemes account for hydrodynamic interactions included on an approximate level. Theoretical predictions for H(q) as a function of the wavenumber q quantitatively agree with experimental results at small protein concentrations obtained using neutron spin echo measurements. At higher concentrations, qualitative agreement is preserved although the calculated hydrodynamic functions are overestimated. We attribute the differences for higher concentrations and lower temperatures to translational-rotational diffusion coupling induced by the shape and interaction anisotropy of particles and clusters, patchiness of the lysozyme particle surfaces, and the intra-cluster dynamics, features not included in our simple globular particle model. The theoretical results for the solution viscosity, η, are in qualitative agreement with our experimental data even at higher concentrations. We demonstrate that semi

  10. On the relationship between NMR-derived amide order parameters and protein backbone entropy changes.

    Science.gov (United States)

    Sharp, Kim A; O'Brien, Evan; Kasinath, Vignesh; Wand, A Joshua

    2015-05-01

    Molecular dynamics simulations are used to analyze the relationship between NMR-derived squared generalized order parameters of amide NH groups and backbone entropy. Amide order parameters (O(2) NH ) are largely determined by the secondary structure and average values appear unrelated to the overall flexibility of the protein. However, analysis of the more flexible subset (O(2) NH  entropy than that reported by the side chain methyl axis order parameters, O(2) axis . A calibration curve for backbone entropy vs. O(2) NH is developed, which accounts for both correlations between amide group motions of different residues, and correlations between backbone and side chain motions. This calibration curve can be used with experimental values of O(2) NH changes obtained by NMR relaxation measurements to extract backbone entropy changes, for example, upon ligand binding. In conjunction with our previous calibration for side chain entropy derived from measured O(2) axis values this provides a prescription for determination of the total protein conformational entropy changes from NMR relaxation measurements. © 2015 Wiley Periodicals, Inc.

  11. Dynamical susceptibility near a long-wavelength critical point with a nonconserved order parameter

    Science.gov (United States)

    Klein, Avraham; Lederer, Samuel; Chowdhury, Debanjan; Berg, Erez; Chubukov, Andrey

    2018-04-01

    We study the dynamic response of a two-dimensional system of itinerant fermions in the vicinity of a uniform (Q =0 ) Ising nematic quantum critical point of d - wave symmetry. The nematic order parameter is not a conserved quantity, and this permits a nonzero value of the fermionic polarization in the d - wave channel even for vanishing momentum and finite frequency: Π (q =0 ,Ωm)≠0 . For weak coupling between the fermions and the nematic order parameter (i.e., the coupling is small compared to the Fermi energy), we perturbatively compute Π (q =0 ,Ωm)≠0 over a parametrically broad range of frequencies where the fermionic self-energy Σ (ω ) is irrelevant, and use Eliashberg theory to compute Π (q =0 ,Ωm) in the non-Fermi-liquid regime at smaller frequencies, where Σ (ω )>ω . We find that Π (q =0 ,Ω ) is a constant, plus a frequency-dependent correction that goes as |Ω | at high frequencies, crossing over to |Ω| 1 /3 at lower frequencies. The |Ω| 1 /3 scaling holds also in a non-Fermi-liquid regime. The nonvanishing of Π (q =0 ,Ω ) gives rise to additional structure in the imaginary part of the nematic susceptibility χ″(q ,Ω ) at Ω >vFq , in marked contrast to the behavior of the susceptibility for a conserved order parameter. This additional structure may be detected in Raman scattering experiments in the d - wave geometry.

  12. Systematic expansion in the order parameter for replica theory of the dynamical glass transition.

    Science.gov (United States)

    Jacquin, Hugo; Zamponi, Francesco

    2013-03-28

    It has been shown recently that predictions from mode-coupling theory for the glass transition of hard-spheres become increasingly bad when dimensionality increases, whereas replica theory predicts a correct scaling. Nevertheless if one focuses on the regime around the dynamical transition in three dimensions, mode-coupling results are far more convincing than replica theory predictions. It seems thus necessary to reconcile the two theoretic approaches in order to obtain a theory that interpolates between low-dimensional, mode-coupling results, and "mean-field" results from replica theory. Even though quantitative results for the dynamical transition issued from replica theory are not accurate in low dimensions, two different approximation schemes--small cage expansion and replicated hyper-netted-chain (RHNC)--provide the correct qualitative picture for the transition, namely, a discontinuous jump of a static order parameter from zero to a finite value. The purpose of this work is to develop a systematic expansion around the RHNC result in powers of the static order parameter, and to calculate the first correction in this expansion. Interestingly, this correction involves the static three-body correlations of the liquid. More importantly, we separately demonstrate that higher order terms in the expansion are quantitatively relevant at the transition, and that the usual mode-coupling kernel, involving two-body direct correlation functions of the liquid, cannot be recovered from static computations.

  13. Evaluation of third order nonlinear optical parameters of CdS/PVA nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Mamta [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160014 (India); Department of Applied Sciences (Physics), UIET, Panjab University, Chandigarh-160014 (India); Tripathi, S. K., E-mail: surya@pu.ac.in, E-mail: surya-tr@yahoo.com [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160014 (India)

    2015-06-24

    CdS nanoparticles dispersed in PVA are prepared by Chemical method at room temperature. The nonlinear optical parameters such as nonlinear absorption (β), nonlinear refractive index (n{sub 2}) and nonlinear susceptibility (χ{sup 3}) are calculated for this sample by using Z-scan technique. CdS/PVA samples show the two photon absorption mechanism. The third order nonlinear susceptibility is calculated from n{sub 2} and β and is found to be of the order of 10{sup −7} – 10{sup −8} m{sup 2}/V{sup 2}. The larger value of third order nonlinear susceptibility is due to dielectric and quantum confinement effect.

  14. Polarized neutron scattering study of the multiple order parameter system NdB4

    Science.gov (United States)

    Metoki, N.; Yamauchi, H.; Matsuda, M.; Fernandez-Baca, J. A.; Watanuki, R.; Hagihala, M.

    2018-05-01

    Neutron polarization analysis has been carried out in order to clarify the magnetic structures of multiple order parameter f -electron system NdB4. We confirmed the noncollinear "all-in all-out" structure (Γ4) of the in-plane moment, which is in good agreement with our previous neutron powder diffraction study. We found that the magnetic moment along the c -axis mc showed diagonally antiferromagnetic structure (Γ10), inconsistent with previously reported "vortex" structure (Γ2). The microscopic mixture of these two structures with q⃗0=(0 ,0 ,0 ) appears in phase II and remains stable in phases III and IV, where an incommensurate modulation coexists. The unusual magnetic ordering is phenomenologically understood via Landau theory with the primary order parameter Γ4 coupled with higher-order secondary order parameter Γ10. The magnetic moments were estimated to be 1.8 ±0.2 and 0.2 ±0.05 μB at T =7.5 K for Γ4 and Γ10, respectively. We also found a long-period incommensurate modulation of the q⃗1=(0 ,0 ,1 /2 ) antiferromagnetic structure of mc with the propagation q⃗s 1=(0.14 ,0.14 ,0.1 ) and q⃗s 2=(0.2 ,0 ,0.1 ) in phase III and IV, respectively. The amplitude of sinusoidal modulation was about mc=1.0 ±0.2 μB at T =1.5 K. The local (0 ,0 ,1 /2 ) structure consists of in-plane ferromagnetic and out-of-plane antiferromagnetic coupling of mc, opposite to the coexisting Γ10. The mc of Γ10 is significantly enhanced up to 0.6 μB at T =1.5 K, which is accompanied by the incommensurate modulations. The Landau phenomenological approach indicates that the higher-order magnetic and/or multipole interactions based on the pseudoquartet f -electron state play important roles.

  15. Fractional Order Controller Designing with Firefly Algorithm and Parameter Optimization for Hydroturbine Governing System

    Directory of Open Access Journals (Sweden)

    Li Junyi

    2015-01-01

    Full Text Available A fractional order PID (FOPID controller, which is suitable for control system designing for being insensitive to the variation in system parameter, is proposed for hydroturbine governing system in the paper. The simultaneous optimization for several parameters of controller, that is, Ki, Kd, Kp, λ, and μ, is done by a recently developed metaheuristic nature-inspired algorithm, namely, the firefly algorithm (FA, for the first time, where the selecting, moving, attractiveness behavior between fireflies and updating of brightness, and decision range are studied in detail to simulate the optimization process. Investigation clearly reveals the advantages of the FOPID controller over the integer controllers in terms of reduced oscillations and settling time. The present work also explores the superiority of FA based optimization technique in finding optimal parameters of the controller. Further, convergence characteristics of the FA are compared with optimum integer order PID (IOPID controller to justify its efficiency. What is more, analysis confirms the robustness of FOPID controller under isolated load operation conditions.

  16. DYNAMIC ESTIMATION FOR PARAMETERS OF INTERFERENCE SIGNALS BY THE SECOND ORDER EXTENDED KALMAN FILTERING

    Directory of Open Access Journals (Sweden)

    P. A. Ermolaev

    2014-03-01

    Full Text Available Data processing in the interferometer systems requires high-resolution and high-speed algorithms. Recurrence algorithms based on parametric representation of signals execute consequent processing of signal samples. In some cases recurrence algorithms make it possible to increase speed and quality of data processing as compared with classic processing methods. Dependence of the measured interferometer signal on parameters of its model and stochastic nature of noise formation in the system is, in general, nonlinear. The usage of nonlinear stochastic filtering algorithms is expedient for such signals processing. Extended Kalman filter with linearization of state and output equations by the first vector parameters derivatives is an example of these algorithms. To decrease approximation error of this method the second order extended Kalman filtering is suggested with additionally usage of the second vector parameters derivatives of model equations. Examples of algorithm implementation with the different sets of estimated parameters are described. The proposed algorithm gives the possibility to increase the quality of data processing in interferometer systems in which signals are forming according to considered models. Obtained standard deviation of estimated amplitude envelope does not exceed 4% of the maximum. It is shown that signal-to-noise ratio of reconstructed signal is increased by 60%.

  17. Behaviour of the order parameter of the simple magnet in an external field

    Directory of Open Access Journals (Sweden)

    M.P.Kozlovskii

    2005-01-01

    Full Text Available The effect of a homogeneous external field on the three-dimensional uniaxial magnet behaviour near the critical point is investigated within the framework of the nonperturbative collective variables method using the ρ4 model. The research is carried out for the low-temperature region. The analytic explicit expressions for the free energy, average spin moment and susceptibility are obtained for weak and strong fields in comparison with the field value belonging to the pseudocritical line. The calculations are performed on the microscopic level without any adjusting parameters. It is established that the long-wave fluctuations of the order parameter play a crucial role in forming a crossover between the temperature-dependence and field-dependence critical behaviour of the system.

  18. Assessing local structure motifs using order parameters for motif recognition, interstitial identification, and diffusion path characterization

    Science.gov (United States)

    Zimmermann, Nils E. R.; Horton, Matthew K.; Jain, Anubhav; Haranczyk, Maciej

    2017-11-01

    Structure-property relationships form the basis of many design rules in materials science, including synthesizability and long-term stability of catalysts, control of electrical and optoelectronic behavior in semiconductors as well as the capacity of and transport properties in cathode materials for rechargeable batteries. The immediate atomic environments (i.e., the first coordination shells) of a few atomic sites are often a key factor in achieving a desired property. Some of the most frequently encountered coordination patterns are tetrahedra, octahedra, body and face-centered cubic as well as hexagonal closed packed-like environments. Here, we showcase the usefulness of local order parameters to identify these basic structural motifs in inorganic solid materials by developing classification criteria. We introduce a systematic testing framework, the Einstein crystal test rig, that probes the response of order parameters to distortions in perfect motifs to validate our approach. Subsequently, we highlight three important application cases. First, we map basic crystal structure information of a large materials database in an intuitive manner by screening the Materials Project (MP) database (61,422 compounds) for element-specific motif distributions. Second, we use the structure-motif recognition capabilities to automatically find interstitials in metals, semiconductor, and insulator materials. Our Interstitialcy Finding Tool (InFiT) facilitates high-throughput screenings of defect properties. Third, the order parameters are reliable and compact quantitative structure descriptors for characterizing diffusion hops of intercalants as our example of magnesium in MnO2-spinel indicates. Finally, the tools developed in our work are readily and freely available as software implementations in the pymatgen library, and we expect them to be further applied to machine-learning approaches for emerging applications in materials science.

  19. Assessing Local Structure Motifs Using Order Parameters for Motif Recognition, Interstitial Identification, and Diffusion Path Characterization

    Directory of Open Access Journals (Sweden)

    Nils E. R. Zimmermann

    2017-11-01

    Full Text Available Structure–property relationships form the basis of many design rules in materials science, including synthesizability and long-term stability of catalysts, control of electrical and optoelectronic behavior in semiconductors, as well as the capacity of and transport properties in cathode materials for rechargeable batteries. The immediate atomic environments (i.e., the first coordination shells of a few atomic sites are often a key factor in achieving a desired property. Some of the most frequently encountered coordination patterns are tetrahedra, octahedra, body and face-centered cubic as well as hexagonal close packed-like environments. Here, we showcase the usefulness of local order parameters to identify these basic structural motifs in inorganic solid materials by developing classification criteria. We introduce a systematic testing framework, the Einstein crystal test rig, that probes the response of order parameters to distortions in perfect motifs to validate our approach. Subsequently, we highlight three important application cases. First, we map basic crystal structure information of a large materials database in an intuitive manner by screening the Materials Project (MP database (61,422 compounds for element-specific motif distributions. Second, we use the structure-motif recognition capabilities to automatically find interstitials in metals, semiconductor, and insulator materials. Our Interstitialcy Finding Tool (InFiT facilitates high-throughput screenings of defect properties. Third, the order parameters are reliable and compact quantitative structure descriptors for characterizing diffusion hops of intercalants as our example of magnesium in MnO2-spinel indicates. Finally, the tools developed in our work are readily and freely available as software implementations in the pymatgen library, and we expect them to be further applied to machine-learning approaches for emerging applications in materials science.

  20. Derivation of the spin-glass order parameter from stochastic thermodynamics

    Science.gov (United States)

    Crisanti, A.; Picco, M.; Ritort, F.

    2018-05-01

    A fluctuation relation is derived to extract the order parameter function q (x ) in weakly ergodic systems. The relation is based on measuring and classifying entropy production fluctuations according to the value of the overlap q between configurations. For a fixed value of q , entropy production fluctuations are Gaussian distributed allowing us to derive the quasi-FDT so characteristic of aging systems. The theory is validated by extracting the q (x ) in various types of glassy models. It might be generally applicable to other nonequilibrium systems and experimental small systems.

  1. Storm Identification, Tracking and Forecasting Using High-Resolution Images of Short-Range X-Band Radar

    Directory of Open Access Journals (Sweden)

    Sajid Shah

    2015-05-01

    Full Text Available Rain nowcasting is an essential part of weather monitoring. It plays a vital role in human life, ranging from advanced warning systems to scheduling open air events and tourism. A nowcasting system can be divided into three fundamental steps, i.e., storm identification, tracking and nowcasting. The main contribution of this work is to propose procedures for each step of the rain nowcasting tool and to objectively evaluate the performances of every step, focusing on two-dimension data collected from short-range X-band radars installed in different parts of Italy. This work presents the solution of previously unsolved problems in storm identification: first, the selection of suitable thresholds for storm identification; second, the isolation of false merger (loosely-connected storms; and third, the identification of a high reflectivity sub-storm within a large storm. The storm tracking step of the existing tools, such as TITANand SCIT, use only up to two storm attributes, i.e., center of mass and area. It is possible to use more attributes for tracking. Furthermore, the contribution of each attribute in storm tracking is yet to be investigated. This paper presents a novel procedure called SALdEdA (structure, amplitude, location, eccentricity difference and areal difference for storm tracking. This work also presents the contribution of each component of SALdEdA in storm tracking. The second order exponential smoothing strategy is used for storm nowcasting, where the growth and decay of each variable of interest is considered to be linear. We evaluated the major steps of our method. The adopted techniques for automatic threshold calculation are assessed with a 97% goodness. False merger and sub-storms within a cluster of storms are successfully handled. Furthermore, the storm tracking procedure produced good results with an accuracy of 99.34% for convective events and 100% for stratiform events.

  2. Impacts of Amazonia biomass burning aerosols assessed from short-range weather forecasts

    Directory of Open Access Journals (Sweden)

    S. R. Kolusu

    2015-11-01

    Full Text Available The direct radiative impacts of biomass burning aerosols (BBA on meteorology are investigated using short-range forecasts from the Met Office Unified Model (MetUM over South America during the South American Biomass Burning Analysis (SAMBBA. The impacts are evaluated using a set of three simulations: (i no aerosols, (ii with monthly mean aerosol climatologies and (iii with prognostic aerosols modelled using the Coupled Large-scale Aerosol Simulator for Studies In Climate (CLASSIC scheme. Comparison with observations show that the prognostic CLASSIC scheme provides the best representation of BBA. The impacts of BBA are quantified over central and southern Amazonia from the first and second day of 2-day forecasts during 14 September–3 October 2012. On average, during the first day of the forecast, including prognostic BBA reduces the clear-sky net radiation at the surface by 15 ± 1 W m−2 and reduces net top-of-atmosphere (TOA radiation by 8 ± 1 W m−2, with a direct atmospheric warming of 7 ± 1 W m−2. BBA-induced reductions in all-sky radiation are smaller in magnitude: 9.0 ± 1 W m−2 at the surface and 4.0 ± 1 W m−2 at TOA. In this modelling study the BBA therefore exert an overall cooling influence on the Earth–atmosphere system, although some levels of the atmosphere are directly warmed by the absorption of solar radiation. Due to the reduction of net radiative flux at the surface, the mean 2 m air temperature is reduced by around 0.1 ± 0.02 °C. The BBA also cools the boundary layer (BL but warms air above by around 0.2 °C due to the absorption of shortwave radiation. The overall impact is to reduce the BL depth by around 19 ± 8 m. These differences in heating lead to a more anticyclonic circulation at 700 hPa, with winds changing by around 0.6 m s−1. Inclusion of climatological or prognostic BBA in the MetUM makes a small but significant improvement in forecasts of temperature and relative humidity, but improvements were

  3. Trapping of a particle in a short-range harmonic potential well

    OpenAIRE

    Castro, L. B.; de Castro, A. S.

    2012-01-01

    Eigenstates of a particle in a localized and unconfined harmonic potential well are investigated. Effects due to the variation of the potential parameters as well as certain results from asymptotic expansions are discussed.

  4. Nonlinear Parameter-Varying AeroServoElastic Reduced Order Model for Aerostructural Sensing and Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the project is to develop reliable reduced order modeling technologies to automatically generate nonlinear, parameter-varying (PV),...

  5. Minimum of the order parameter fluctuations of seismicity before major earthquakes in Japan.

    Science.gov (United States)

    Sarlis, Nicholas V; Skordas, Efthimios S; Varotsos, Panayiotis A; Nagao, Toshiyasu; Kamogawa, Masashi; Tanaka, Haruo; Uyeda, Seiya

    2013-08-20

    It has been shown that some dynamic features hidden in the time series of complex systems can be uncovered if we analyze them in a time domain called natural time χ. The order parameter of seismicity introduced in this time domain is the variance of χ weighted for normalized energy of each earthquake. Here, we analyze the Japan seismic catalog in natural time from January 1, 1984 to March 11, 2011, the day of the M9 Tohoku earthquake, by considering a sliding natural time window of fixed length comprised of the number of events that would occur in a few months. We find that the fluctuations of the order parameter of seismicity exhibit distinct minima a few months before all of the shallow earthquakes of magnitude 7.6 or larger that occurred during this 27-y period in the Japanese area. Among the minima, the minimum before the M9 Tohoku earthquake was the deepest. It appears that there are two kinds of minima, namely precursory and nonprecursory, to large earthquakes.

  6. Deterministic flows of order-parameters in stochastic processes of quantum Monte Carlo method

    International Nuclear Information System (INIS)

    Inoue, Jun-ichi

    2010-01-01

    In terms of the stochastic process of quantum-mechanical version of Markov chain Monte Carlo method (the MCMC), we analytically derive macroscopically deterministic flow equations of order parameters such as spontaneous magnetization in infinite-range (d(= ∞)-dimensional) quantum spin systems. By means of the Trotter decomposition, we consider the transition probability of Glauber-type dynamics of microscopic states for the corresponding (d + 1)-dimensional classical system. Under the static approximation, differential equations with respect to macroscopic order parameters are explicitly obtained from the master equation that describes the microscopic-law. In the steady state, we show that the equations are identical to the saddle point equations for the equilibrium state of the same system. The equation for the dynamical Ising model is recovered in the classical limit. We also check the validity of the static approximation by making use of computer simulations for finite size systems and discuss several possible extensions of our approach to disordered spin systems for statistical-mechanical informatics. Especially, we shall use our procedure to evaluate the decoding process of Bayesian image restoration. With the assistance of the concept of dynamical replica theory (the DRT), we derive the zero-temperature flow equation of image restoration measure showing some 'non-monotonic' behaviour in its time evolution.

  7. Simulation of Higher-Order Electrical Circuits with Stochastic Parameters via SDEs

    Directory of Open Access Journals (Sweden)

    BRANCIK, L.

    2013-02-01

    Full Text Available The paper deals with a technique for the simulation of higher-order electrical circuits with parameters varying randomly. The principle consists in the utilization of the theory of stochastic differential equations (SDE, namely the vector form of the ordinary SDEs. Random changes of both excitation voltage and some parameters of passive circuit elements are considered, and circuit responses are analyzed. The voltage and/or current responses are computed and represented in the form of the sample means accompanied by their confidence intervals to provide reliable estimates. The method is applied to analyze responses of the circuit models of optional orders, specially those consisting of a cascade connection of the RLGC networks. To develop the model equations the state-variable method is used, afterwards a corresponding vector SDE is formulated and a stochastic Euler numerical method applied. To verify the results the deterministic responses are also computed by the help of the PSpice simulator or the numerical inverse Laplace transforms (NILT procedure in MATLAB, while removing random terms from the circuit model.

  8. Order parameter in CeCu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Vieyra, Hugo A.; Brando, Manuel; Oeschler, Niels; Seiro, Silvia; Geibel, Christoph; Steglich, Frank [Max-Planck-Institute for Chemical Physics of Solids, Dresden (Germany); Jeevan, Hirale S. [I. Physikalisches Institut, Georg-August-Universitaet Goettingen (Germany); Parker, David [US Naval Research Laboratory, Washington, DC (United States)

    2011-07-01

    Understanding the interplay between magnetism and unconventional superconductivity remains a key challenge in solid-state physics. A clear example is the archetypical heavy-fermion compound CeCu{sub 2}Si{sub 2} which exhibits superconductivity (T{sub c}=600 mK) in the vicinity of a magnetic quantum critical point. It is believed that magnetic fluctuations mediate superconductivity and its order parameter possesses d-wave symmetry, both ideas still under debate. In this work, a high-quality single crystal with a purely superconducting ground state (S type) has been chosen to investigate the low-temperature thermal- and electric-transport characteristics of the superconducting state. Non-vanishing contributions of low-energy quasiparticle excitations to the thermal transport ({kappa}{sub 0}/T>0) suggest the presence of nodal structure in CeCu{sub 2}Si{sub 2}. In turn, angle-dependent resistivity measurements of the upper critical field H{sub c2} point towards unconventional superconductivity with d-wave symmetry of the order parameter. Theoretical calculations reveal the strong influence of Pauli paramagnetic effects and a d{sub xy} symmetry of the gap function.

  9. Higher-Order Approximations of Motion of a Nonlinear Oscillator Using the Parameter Expansion Technique

    Science.gov (United States)

    Ganji, S. S.; Domairry, G.; Davodi, A. G.; Babazadeh, H.; Seyedalizadeh Ganji, S. H.

    The main objective of this paper is to apply the parameter expansion technique (a modified Lindstedt-Poincaré method) to calculate the first, second, and third-order approximations of motion of a nonlinear oscillator arising in rigid rod rocking back. The dynamics and frequency of motion of this nonlinear mechanical system are analyzed. A meticulous attention is carried out to the study of the introduced nonlinearity effects on the amplitudes of the oscillatory states and on the bifurcation structures. We examine the synchronization and the frequency of systems using both the strong and special method. Numerical simulations and computer's answers confirm and complement the results obtained by the analytical approach. The approach proposes a choice to overcome the difficulty of computing the periodic behavior of the oscillation problems in engineering. The solutions of this method are compared with the exact ones in order to validate the approach, and assess the accuracy of the solutions. In particular, APL-PM works well for the whole range of oscillation amplitudes and excellent agreement of the approximate frequency with the exact one has been demonstrated. The approximate period derived here is accurate and close to the exact solution. This method has a distinguished feature which makes it simple to use, and also it agrees with the exact solutions for various parameters.

  10. Spectral Properties, Generation Order Parameters, and Luminosities for Spin-powered X-Ray Pulsars

    Science.gov (United States)

    Wang, Wei; Zhao, Yongheng

    2004-02-01

    We show the spectral properties of 15 spin-powered X-ray pulsars, and the correlation between the average power-law photon index and spin-down rate. Generation order parameters (GOPs) based on polar cap models are introduced to characterize the X-ray pulsars. We calculate three definitions of generation order parameters arising from the different effects of magnetic and electric fields on photon absorption during cascade processes, and study the relations between the GOPs and spectral properties of X-ray pulsars. There exists a possible correlation between the photon index and GOP in our pulsar sample. Furthermore, we present a method stemming from the concept of GOPs to estimate the nonthermal X-ray luminosity for spin-powered pulsars. Then X-ray luminosity is calculated in the context of our polar cap accelerator model, which is consistent with most observed X-ray pulsar data. The ratio between the X-ray luminosity estimated by our method and the pulsar's spin-down power is consistent with the LX~10-3Lsd feature.

  11. Health Parameter Estimation with Second-Order Sliding Mode Observer for a Turbofan Engine

    Directory of Open Access Journals (Sweden)

    Xiaodong Chang

    2017-07-01

    Full Text Available In this paper the problem of health parameter estimation in an aero-engine is investigated by using an unknown input observer-based methodology, implemented by a second-order sliding mode observer (SOSMO. Unlike the conventional state estimator-based schemes, such as Kalman filters (KF and sliding mode observers (SMO, the proposed scheme uses a “reconstruction signal” to estimate health parameters modeled as artificial inputs, and is not only applicable to long-time health degradation, but reacts much quicker in handling abrupt fault cases. In view of the inevitable uncertainties in engine dynamics and modeling, a weighting matrix is created to minimize such effect on estimation by using the linear matrix inequalities (LMI. A big step toward uncertainty modeling is taken compared with our previous SMO-based work, in that uncertainties are considered in a more practical form. Moreover, to avoid chattering in sliding modes, the super-twisting algorithm (STA is employed in observer design. Various simulations are carried out, based on the comparisons between the KF-based scheme, the SMO-based scheme in our earlier research, and the proposed method. The results consistently demonstrate the capabilities and advantages of the proposed approach in health parameter estimation.

  12. Control of strength and stability of emulsion-gels by a combination of long- and short-range interactions

    NARCIS (Netherlands)

    Blijdenstein, T.B.J.; Hendriks, W.P.G.; Linden, van der E.; Vliet, van T.; Aken, van G.A.

    2003-01-01

    This paper discusses the change in phase behavior and mechanical properties of oil-in-water emulsion gels brought about by variation of long- and short-range attractive interactions. The model system studied consisted of oil droplets stabilized by the protein -lactoglobulin (-lg). A long-range

  13. On-chip patch antenna on InP substrate for short-range wireless communication at 140 GHz

    DEFF Research Database (Denmark)

    Dong, Yunfeng; Johansen, Tom Keinicke; Zhurbenko, Vitaliy

    2017-01-01

    This paper presents the design of an on-chip patch antenna on indium phosphide (InP) substrate for short-range wireless communication at 140 GHz. The antenna shows a simulated gain of 5.3 dBi with 23% bandwidth at 140 GHz and it can be used for either direct chip-to-chip communication or chip...

  14. Two-nucleon electromagnetic current in chiral effective field theory: One-pion exchange and short-range contributions

    International Nuclear Information System (INIS)

    Koelling, S.; Epelbaum, E.; Krebs, H.; Meissner, U.-G.

    2011-01-01

    We derive the leading one-loop contribution to the one-pion exchange and short-range two-nucleon electromagnetic current operator in the framework of chiral effective field theory. The derivation is carried out using the method of unitary transformation. Explicit results for the current and charge densities are given in momentum and coordinate space.

  15. Renormalization of the three-boson system with short-range interactions revisited

    International Nuclear Information System (INIS)

    Epelbaum, E.; Gegelia, J.; Meissner, Ulf G.; Yao, De-Liang

    2017-01-01

    We consider renormalization of the three-body scattering problem in low-energy effective field theory of self-interacting scalar particles by applying time-ordered perturbation theory to the manifestly Lorentz-invariant formulation. The obtained leading-order equation is perturbatively renormalizable and non-perturbatively finite and does not require a three-body counter term in contrast to its non-relativistic approximation. (orig.)

  16. Local tuning of the order parameter in superconducting weak links: A zero-inductance nanodevice

    Science.gov (United States)

    Winik, Roni; Holzman, Itamar; Dalla Torre, Emanuele G.; Buks, Eyal; Ivry, Yachin

    2018-03-01

    Controlling both the amplitude and the phase of the superconducting quantum order parameter (" separators="|ψ ) in nanostructures is important for next-generation information and communication technologies. The lack of electric resistance in superconductors, which may be advantageous for some technologies, hinders convenient voltage-bias tuning and hence limits the tunability of ψ at the microscopic scale. Here, we demonstrate the local tunability of the phase and amplitude of ψ, obtained by patterning with a single lithography step a Nb nano-superconducting quantum interference device (nano-SQUID) that is biased at its nanobridges. We accompany our experimental results by a semi-classical linearized model that is valid for generic nano-SQUIDs with multiple ports and helps simplify the modelling of non-linear couplings among the Josephson junctions. Our design helped us reveal unusual electric characteristics with effective zero inductance, which is promising for nanoscale magnetic sensing and quantum technologies.

  17. Evaluation of higher order statistics parameters for multi channel sEMG using different force levels.

    Science.gov (United States)

    Naik, Ganesh R; Kumar, Dinesh K

    2011-01-01

    The electromyograpy (EMG) signal provides information about the performance of muscles and nerves. The shape of the muscle signal and motor unit action potential (MUAP) varies due to the movement of the position of the electrode or due to changes in contraction level. This research deals with evaluating the non-Gaussianity in Surface Electromyogram signal (sEMG) using higher order statistics (HOS) parameters. To achieve this, experiments were conducted for four different finger and wrist actions at different levels of Maximum Voluntary Contractions (MVCs). Our experimental analysis shows that at constant force and for non-fatiguing contractions, probability density functions (PDF) of sEMG signals were non-Gaussian. For lesser MVCs (below 30% of MVC) PDF measures tends to be Gaussian process. The above measures were verified by computing the Kurtosis values for different MVCs.

  18. Excitonic magnet in external field: Complex order parameter and spin currents

    Science.gov (United States)

    Geffroy, D.; Hariki, A.; Kuneš, J.

    2018-04-01

    We investigate spin-triplet exciton condensation in the two-orbital Hubbard model close to half-filling by means of dynamical mean-field theory. Employing an impurity solver that handles complex off-diagonal hybridization functions, we study the behavior of excitonic condensate in stoichiometric and doped systems subject to external magnetic field. We find a general tendency of the triplet order parameter to lie perpendicular with the applied field and identify exceptions from this rule. For solutions exhibiting k -odd spin textures, we discuss the Bloch theorem, which, in the absence of spin-orbit coupling, forbids the appearance of spontaneous net spin current. We demonstrate that the Bloch theorem is not obeyed by the dynamical mean-field theory.

  19. Quasiparticles and order parameter near quantum phase transition in heavy fermion metals

    Energy Technology Data Exchange (ETDEWEB)

    Shaginyan, V.R. [Petersburg Nuclear Physics Institute, Russian Academy of Sciences, Gatchina 188300 (Russian Federation) and CTSPS, Clark Atlanta University, Atlanta, GA 30314 (United States)]. E-mail: vrshag@thd.pnpi.spb.ru; Msezane, A.Z. [CTSPS, Clark Atlanta University, Atlanta, GA 30314 (United States); Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); A.F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation)

    2005-05-02

    It is shown that the Landau paradigm based upon both the quasiparticle concept and the notion of the order parameter is valid and can be used to explain the anomalous behavior of the heavy fermion metals near quantum critical points. The understanding of this phenomenon has been problematic largely because of the absence of theoretical guidance. Exploiting this paradigm and the fermion condensation quantum phase transition, we investigate the anomalous behavior of the heavy electron liquid near its critical point at different temperatures and applied magnetic fields. We show that this anomalous behavior is universal and can be used to capture the essential aspects of recent experiments on heavy-fermion metals at low temperatures.

  20. Statistical model with two order parameters for ductile and soft fiber bundles in nanoscience and biomaterials.

    Science.gov (United States)

    Rinaldi, Antonio

    2011-04-01

    Traditional fiber bundles models (FBMs) have been an effective tool to understand brittle heterogeneous systems. However, fiber bundles in modern nano- and bioapplications demand a new generation of FBM capturing more complex deformation processes in addition to damage. In the context of loose bundle systems and with reference to time-independent plasticity and soft biomaterials, we formulate a generalized statistical model for ductile fracture and nonlinear elastic problems capable of handling more simultaneous deformation mechanisms by means of two order parameters (as opposed to one). As the first rational FBM for coupled damage problems, it may be the cornerstone for advanced statistical models of heterogeneous systems in nanoscience and materials design, especially to explore hierarchical and bio-inspired concepts in the arena of nanobiotechnology. Applicative examples are provided for illustrative purposes at last, discussing issues in inverse analysis (i.e., nonlinear elastic polymer fiber and ductile Cu submicron bars arrays) and direct design (i.e., strength prediction).

  1. Critical behavior of order-parameter fluctuations in liquid 4He near T/sub lambda/

    International Nuclear Information System (INIS)

    Lambert, B.; Perzynski, R.; Salin, D.

    1979-01-01

    We hve measured the critical attenuation of first sound in liquid 4 He from 550 to 1700 MHz. We can describe the attenuation due to the fluctuations of the order parameter up to 1.7 GHz, using experimental data at lower frequencies from various authors. Above T/sub lambda/, the fluctuations are the only phenomena and are analyzed with a scaling function of ωtau 2 with a characteristic time tau 2 = 2 x 10 -12 x t/sup -1.062/ sec, t = vertical-bar (T-T/sub lambda/)/T/sub lambda/vertical-bar. Below T/sub lambda/, several phenomena are present. In the range of 1 GHz, the main contribution is due to the fluctuations. We demonstrate experimentally that the fluctuation attenuation is not symmetric about T/sub lambda/. We fit our data with a scaling function of ωtau 2

  2. Hannay angle. Yet another symmetry-protected topological order parameter in classical mechanics

    International Nuclear Information System (INIS)

    Kariyado, Toshikaze; Hatsugai, Yasuhiro

    2016-01-01

    The topological way of thinking now goes beyond quantum solids, and topological characters of classical mechanical systems obeying Newton's law are attracting current interest. To provide a physical insight into the topological numbers in mechanics, we demonstrate the use of the Hannay angle, a “classical” Berry phase, as a symmetry-protected topological order parameter. The Hannay angle is derived using a canonical transformation that maps Newton's equation to a Schrödinger-type equation, and the condition for the quantization is discussed in connection with the symmetry in mechanics. Also, we demonstrate the use of the Hannay angle for a topological characterization of a spring-mass model focusing on the bulk-edge correspondence. (author)

  3. Reduced order modeling and parameter identification of a building energy system model through an optimization routine

    International Nuclear Information System (INIS)

    Harish, V.S.K.V.; Kumar, Arun

    2016-01-01

    Highlights: • A BES model based on 1st principles is developed and solved numerically. • Parameters of lumped capacitance model are fitted using the proposed optimization routine. • Validations are showed for different types of building construction elements. • Step response excitations for outdoor air temperature and relative humidity are analyzed. - Abstract: Different control techniques together with intelligent building technology (Building Automation Systems) are used to improve energy efficiency of buildings. In almost all control projects, it is crucial to have building energy models with high computational efficiency in order to design and tune the controllers and simulate their performance. In this paper, a set of partial differential equations are formulated accounting for energy flow within the building space. These equations are then solved as conventional finite difference equations using Crank–Nicholson scheme. Such a model of a higher order is regarded as a benchmark model. An optimization algorithm has been developed, depicted through a flowchart, which minimizes the sum squared error between the step responses of the numerical and the optimal model. Optimal model of the construction element is nothing but a RC-network model with the values of Rs and Cs estimated using the non-linear time invariant constrained optimization routine. The model is validated with comparing the step responses with other two RC-network models whose parameter values are selected based on a certain criteria. Validations are showed for different types of building construction elements viz., low, medium and heavy thermal capacity elements. Simulation results show that the optimal model closely follow the step responses of the numerical model as compared to the responses of other two models.

  4. Perturbation theory for nematic liquid crystals of axially symmetric molecules: Evaluation of fourth rank orientational order parameter

    International Nuclear Information System (INIS)

    Singh, K.

    1993-11-01

    Using a statistical mechanical perturbation theory for isotropic-nematic transition we report a calculation of second and fourth rank orientation order parameters and thermodynamic properties for a model system of prolate ellipsoids of revolution parameterized by its length-to-width ratio. The influence of attractive potential represented by dispersion interaction on a variety of thermodynamic properties is analysed. Inclusion of fourth rank orientational order parameter in calculation slightly changes the transition parameter. (author). 7 refs, 1 tab

  5. Order parameter effect critical fields and current of Y1–xPrx:123 superconductors

    Directory of Open Access Journals (Sweden)

    Sedky A.

    2018-03-01

    Full Text Available Fluctuation induced conductivity by Pr substitution at Y sites of Y1-xPrx:123 superconductors is reported. It is found that the mean field temperature Tcmf, deduced from the peak of dρ/dT versus T plot, gradually decreases by increasing Pr up to 0.40. The order parameter dimensionality (OPD is estimated from the slope of the logarithmic plot between excess conductivity Δσ and reduced temperature є. Interestingly, the crossover from 2D to 3D is obtained for samples with Pr = 0.00, 0.10 and 0.20, while with increasing Pr up to 0.40, the crossover from 0D to quasi-2D is obtained. On the other hand, the calculated values of interlayer coupling, coherence lengths, critical fields and critical current decrease with increasing Pr up to 0.20, but with the further increase of Pr, up to 0.40, they increase. The hole carriers/Cu ions anisotropy and G-L parameter gradually increase with Pr up to 0.40. Our results are discussed in terms of the effects of Pr substitution at Y site, such as oxygen rearrangements, anisotropy, hybridization and localization of holes in the overdoped region.

  6. Parameter Sensitivity of High–Order Equivalent Circuit Models Of Turbine Generator

    Directory of Open Access Journals (Sweden)

    T. Niewierowicz–Swiecicka

    2010-01-01

    Full Text Available This work shows the results of a parametric sensitivity analysis applied to a state–space representation of high–order two–axis equivalent circuits (ECs of a turbo generator (150 MVA, 120 MW, 13.8 kV y 50 Hz. The main purpose of this study is to evaluate each parameter impact on the transient response of the analyzed two–axis models –d–axis ECs with one to five damper branches and q–axis ECs from one to four damper branches–. The parametric sensitivity concept is formulated in a general context and the sensibility function is established from the generator response to a short circuit condition. Results ponder the importance played by each parameter in the model behavior. The algorithms were design within MATLAB® environment. The study gives way to conclusions on electromagnetic aspects of solid rotor synchronous generators that have not been previously studied. The methodology presented here can be applied to any other physical system.

  7. Short-range and long-range correlations in DIS at HERA

    International Nuclear Information System (INIS)

    Chekanov, S. V.; Zawiejski, L.

    1999-01-01

    Correlations in deep-inelastic scattering (DIS) at HERA are investigated in order to test perturbative QCD and quark fragmentation universality. Two-particle correlations at small angular separations are measured in the Breit frame and compared to e + e - collisions. Also presented are the correlations between the current and target regions of the Breit frame

  8. Dimensional study of the caging order parameter at the glass transition.

    Science.gov (United States)

    Charbonneau, Patrick; Ikeda, Atsushi; Parisi, Giorgio; Zamponi, Francesco

    2012-08-28

    The glass problem is notoriously hard and controversial. Even at the mean-field level, little is agreed upon regarding why a fluid becomes sluggish while exhibiting but unremarkable structural changes. It is clear, however, that the process involves self-caging, which provides an order parameter for the transition. It is also broadly assumed that this cage should have a gaussian shape in the mean-field limit. Here we show that this ansatz does not hold. By performing simulations as a function of spatial dimension d, we find the cage to keep a nontrivial form. Quantitative mean-field descriptions of the glass transition, such as mode-coupling theory, density functional theory, and replica theory, all miss this crucial element. Although the mean-field random first-order transition scenario of the glass transition is qualitatively supported here and non-mean-field corrections are found to remain small on decreasing d, reconsideration of its implementation is needed for it to result in a coherent description of experimental observations.

  9. METABOLIC AND BEHAVIORAL PARAMETERS IN NEWBORN PIGLETS IN RELATION TO BIRTH ORDER

    Directory of Open Access Journals (Sweden)

    H. SĂRĂNDAN

    2008-05-01

    Full Text Available The experiment had 2 phases:During the first phase 19 sows were monitored during farrowing; the piglets were numbered according to birth order, they were weighed and there were recorded the time each piglet was born and when it first suckled. There was calculated the time from the beginning of the farrowing until the time each piglet was born (TNPP and the time from birth until the first suckle (TPS. A statistical correlation was established between these parameters.During the second experimental phase, for 49 piglets from 5 sows were determined: birth weight, TPS, glycemia at birth (G0 and after the first suckle (G1, rectal temperature at birth (T0 and after the first suckles (T1. This data was statistically analyzed using the Mann-Whitney U test.Respecting the birth order, TPS is shorter for piglets born last (p<0.05. Average TPS was 23.04±2.49 minutes; during this time glycemia rises from 58.35 mg% to 64.35 mg% and rectal temperature drops from 38.58°C to 37.35°C. T0 is positively correlated with G0 (p<0.01 with G1 (p<0.01 and T1 (p<0.01. G0 is highly correlated to G1 (r=0.8855; p=0.

  10. Exposure caused by wireless technologies used for short-range indoor communication in homes and offices

    International Nuclear Information System (INIS)

    Schmid, G.; Lager, D.; Preiner, P.; Ueberbacher, R.; Cecil, S.

    2007-01-01

    In order to estimate typical radio frequency exposures from indoor used wireless communication technologies applied in homes and offices, WLAN, Bluetooth and Digital Enhanced Cordless Telecommunications systems, as well as baby surveillance devices and wireless headphones for indoor usage, have been investigated by measurements and numerical computations. Based on optimised measurement methods, field distributions and resulting exposure were assessed on selected products and real exposure scenarios. Additionally, generic scenarios have been investigated on the basis of numerical computations. The obtained results demonstrate that under usual conditions the resulting spatially (over body dimensions) averaged and 6-min time-averaged exposure for persons in the radio frequency fields of the considered applications is below ∼0.1% of the reference level for power density according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines published in 1998. Spatial and temporal peak values can be considerably higher by 2-3 orders of magnitude. In case of some transmitting devices operated in close proximity to the body (e.g. WLAN transmitters), local exposure can reach the same order of magnitude as the basic restriction; however, none of the devices considered in this study exceeded the limits according to the ICNIRP guidelines. (authors)

  11. Exposure caused by wireless technologies used for short-range indoor communication in homes and offices.

    Science.gov (United States)

    Schmid, G; Lager, D; Preiner, P; Uberbacher, R; Cecil, S

    2007-01-01

    In order to estimate typical radio frequency exposures from indoor used wireless communication technologies applied in homes and offices, WLAN, Bluetooth and Digital Enhanced Cordless Telecommunications systems, as well as baby surveillance devices and wireless headphones for indoor usage, have been investigated by measurements and numerical computations. Based on optimised measurement methods, field distributions and resulting exposure were assessed on selected products and real exposure scenarios. Additionally, generic scenarios have been investigated on the basis of numerical computations. The obtained results demonstrate that under usual conditions the resulting spatially (over body dimensions) averaged and 6-min time-averaged exposure for persons in the radio frequency fields of the considered applications is below approximately 0.1% of the reference level for power density according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines published in 1998. Spatial and temporal peak values can be considerably higher by 2-3 orders of magnitude. In case of some transmitting devices operated in close proximity to the body (e.g. WLAN transmitters), local exposure can reach the same order of magnitude as the basic restriction; however, none of the devices considered in this study exceeded the limits according to the ICNIRP guidelines.

  12. Ordering parameters of three-dimensional ordered quantum-dot lattices determined by anomalous x-ray diffraction

    International Nuclear Information System (INIS)

    Lechner, R.T.; Springholz, G.; Stangl, J.; Raab, A.; Bauer, G.; Schuelli, T.U.; Holy, V.; Metzger, T.H.

    2004-01-01

    Three dimensional (3D) quantum dot structures can be obtained, e.g., by the growth of self-assembled quantum dot multilayers in which vertically and laterally ordered dot superstructures are formed as a result of the elastic interlayer dot interactions between the dots. This not only results in a significant narrowing of the size distribution, but different 3D interlayer correlations can be obtained by changes in the spacer thickness, as has been demonstrated for the PbSe/PbEuTe quantum dot material system. Apart from microscopic techniques, x-ray diffraction is a very powerful tool to characterize the ordering in such 3D assembled quantum dot structures. However, the analysis of the diffraction spectra is usually complicated by the weak scattering contrast between the self-assembled quantum dots and the surrounding matrix material. In the present work, we therefore employ anomalous x-ray diffraction with synchrotron radiation to drastically enhance the chemical contrast in such multilayers by tuning the wavelength close to an inner shell absorption resonance. This technique is applied to determine the ordering of differently stacked self-assembled PbSe quantum dot lattices fabricated by molecular beam epitaxy. In this case, the x-ray wavelength is tuned to the Pb M-shell at 5.1 Aato enhance the scattering contrast between the PbSe dots and the matrix material in comparison to the results obtained using conventional x-ray wavelengths around 1.5 Aa. As a result, it is shown that the lateral ordering is significantly better for 3D trigonal PbSe dot superlattices as compared to those with 3D hexagonal dot arrangement. (author)

  13. Development and application of a water calorimeter for the absolute dosimetry of short-range particle beams

    Science.gov (United States)

    Renaud, J.; Rossomme, S.; Sarfehnia, A.; Vynckier, S.; Palmans, H.; Kacperek, A.; Seuntjens, J.

    2016-09-01

    In this work, we describe a new design of water calorimeter built to measure absorbed dose in non-standard radiation fields with reference depths in the range of 6-20 mm, and its initial testing in clinical electron and proton beams. A functioning calorimeter prototype with a total water equivalent thickness of less than 30 mm was constructed in-house and used to obtain measurements in clinical accelerator-based 6 MeV and 8 MeV electron beams and cyclotron-based 60 MeV monoenergetic and modulated proton beams. Corrections for the conductive heat transfer due to dose gradients and non-water materials was also accounted for using a commercial finite element method software package. Absorbed dose to water was measured with an associated type A standard uncertainty of approximately 0.4% and 0.2% for the electron and proton beam experiments, respectively. In terms of thermal stability, drifts were on the order of a couple of hundred µK min-1, with a short-term variation of 5-10 µK. Heat transfer correction factors ranged between 1.021 and 1.049. The overall combined standard uncertainty on the absorbed dose to water was estimated to be 0.6% for the 6 MeV and 8 MeV electron beams, as well as for the 60 MeV monoenergetic protons, and 0.7% for the modulated 60 MeV proton beam. This study establishes the feasibility of developing an absorbed dose transfer standard for short-range clinical electrons and protons and forms the basis for a transportable dose standard for direct calibration of ionization chambers in the user’s beam. The largest contributions to the combined standard uncertainty were the positioning (⩽0.5%) and the correction due to conductive heat transfer (⩽0.4%). This is the first time that water calorimetry has been used in such a low energy proton beam.

  14. Short-Range Correlated Magnetic Core-Shell CrO₂/Cr₂O₃ Nanorods: Experimental Observations and Theoretical Considerations.

    Science.gov (United States)

    Gandhi, Ashish C; Li, Tai-Yue; Chan, Ting Shan; Wu, Sheng Yun

    2018-05-09

    With the evolution of synthesis and the critical characterization of core-shell nanostructures, short-range magnetic correlation is of prime interest in employing their properties to develop novel devices and widespread applications. In this regard, a novel approach of the magnetic core-shell saturated magnetization (CSSM) cylinder model solely based on the contribution of saturated magnetization in one-dimensional CrO₂/Cr₂O₃ core-shell nanorods (NRs) has been developed and applied for the determination of core-diameter and shell-thickness. The nanosized effect leads to a short-range magnetic correlation of ferromagnetic core-CrO₂ extracted from CSSM, which can be explained using finite size scaling method. The outcome of this study is important in terms of utilizing magnetic properties for the critical characterization of core-shell nanomagnetic materials.

  15. Properties of short-range and long-range correlation energy density functionals from electron-electron coalescence

    International Nuclear Information System (INIS)

    Gori-Giorgi, Paola; Savin, Andreas

    2006-01-01

    The combination of density-functional theory with other approaches to the many-electron problem through the separation of the electron-electron interaction into a short-range and a long-range contribution is a promising method, which is raising more and more interest in recent years. In this work some properties of the corresponding correlation energy functionals are derived by studying the electron-electron coalescence condition for a modified (long-range-only) interaction. A general relation for the on-top (zero electron-electron distance) pair density is derived, and its usefulness is discussed with some examples. For the special case of the uniform electron gas, a simple parametrization of the on-top pair density for a long-range only interaction is presented and supported by calculations within the ''extended Overhauser model.'' The results of this work can be used to build self-interaction corrected short-range correlation energy functionals

  16. Ionization from short-range potential under action of electromagnetic field of complex configuration

    CERN Document Server

    Rodionov, V N; Kravtsova, G A

    2002-01-01

    The transcendental equation for the complex energy is obtained on the basis of the exactly solvable 3D model of the short-acting potential and the Green time function in the intensive electromagnetic field, constituting the combination of the constant magnetic field and the circular-polarization wave field. The electron quasistationary states parameters in the delta-potential with an account of the action of the intensive external field of complex configuration are calculated. The problem on the possibility of stabilizing the bound states decay of the spinor and scalar particles through the intensive magnetic field is clarified. It is established that the obtained results regime the reexamination of the accepted notion on the stabilizing role of the strong magnetic field by the atoms ionization

  17. SHORT-RANGE WAKEFIELD IN A FLAT PILLBOX CAVITY GENERATED BY A SUB-RELATIVISTIC BEAM BUNCH

    International Nuclear Information System (INIS)

    WANG, H.; PALMER, R.B.; GALLARDO, J.

    2001-01-01

    The short-range wakefield between two parallel conducting plates generated by a sub-relativistic beam bunch has been solved analytically by the image charge method in time domain. Comparing with the traditional modal analysis in frequency domain, this algorithm simplifies the mathematics and reveals in greater details the physics of electromagnetic field generation, propagation, reflection and causality. The calculated results have an excellent agreement with MAFIA and ABC1 simulations in all range of beam velocities

  18. New spin source to search for scalar-pseudoscalar couplings at short range

    International Nuclear Information System (INIS)

    Hammond, G. D.; Pulido Paton, A.; Speake, C. C.; Trenkel, C.; Rochester, G. K.; Shaul, D.; Sumner, T. J.

    2008-01-01

    We describe the design and performance of a new source of polarized spins that can be employed in experiments that search for macroscopic interactions between particles with intrinsic spin. In this article we concentrate on the analysis of the performance of the spin source in generating putative scalar-pseudoscalar forces. We outline two methods of calculating the magnitude of such forces and compare the predictions of the models. We discuss the manufacture of the spin source and the measurements that we have carried out in order to place upper limits on systematic effects that would limit the sensitivity of such searches. We have shown, in a recent article to Physical Review Letters [G. D. Hammond, C. C. Speake, C. Trenkel, and A. Pulido-Paton, Phys. Rev. Lett. 98, 081101 (2007)], that the combination of the spin source together with the torque sensitivity of our torsion balance improves constraints on the coupling strength of macroscopic scalar-pseudoscalar interactions by 10 orders of magnitude at a range of 1 mm. This paper further supports that work and provides a detailed description and characterization of the spin source

  19. Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

  20. Application of short-range dual-Doppler lidars to evaluate the coherence of turbulence

    Science.gov (United States)

    Cheynet, Etienne; Jakobsen, Jasna Bogunović; Snæbjörnsson, Jónas; Mikkelsen, Torben; Sjöholm, Mikael; Mann, Jakob; Hansen, Per; Angelou, Nikolas; Svardal, Benny

    2016-12-01

    Two synchronized continuous wave scanning lidars are used to study the coherence of the along-wind and across-wind velocity components. The goal is to evaluate the potential of the lidar technology for application in wind engineering. The wind lidars were installed on the Lysefjord Bridge during four days in May 2014 to monitor the wind field in the horizontal plane upstream of the bridge deck. Wind records obtained by five sonic anemometers mounted on the West side of the bridge are used as reference data. Single- and two-point statistics of wind turbulence are studied, with special emphasis on the root-coherence and the co-coherence of turbulence. A four-parameter decaying exponential function has been fitted to the measured co-coherence, and a good agreement is observed between data obtained by the sonic anemometers and the lidars. The root-coherence of turbulence is compared to theoretical models. The analytical predictions agree rather well with the measured coherence for the along-wind component. For increasing wavenumbers, larger discrepancies are, however, noticeable between the measured coherence and the theoretical predictions. The WindScanners are observed to slightly overestimate the integral length scales, which could not be explained by the laser beam averaging effect alone. On the other hand, the spatial averaging effect does not seem to have any significant effect on the coherence.

  1. Structure of the conversion laws in quantum integrable spin chains with short range interactions

    International Nuclear Information System (INIS)

    Grabowski, M.P.; Mathieu, P.

    1995-01-01

    The authors present a detailed analysis of the structure of the conservation laws in quantum integrable chains of the XYZ-type and in the Hubbard model. The essential tool for the former class of models is the boost operator, which provides a recursive way of calculating the integrals of motion. With its help, they establish the general form of the XYZ conserved charges in terms of simple polynomials in spin variables and derive recursion relations for the relative coefficients of these polynomials. Although these relations are difficult to solve in general, a subset of the coefficients can be determined. Moreover, for two submodels of the XYZ chain, namely the XXX and XY cases, all the charges can be calculated in closed form. Using this approach, the authors rederive the known expressions for the XY charges in a novel way. For the XXX case. a simple description of conserved charges is found in terms of a Catalan tree. This construction is generalized for the su(M) invariant integrable chain. They also investigate the circumstances permitting the existence of a recursive (ladder) operator in general quantum integrable systems. They indicate that a quantum ladder operator can be traced back to the presence of a Hamiltonian mastersymmetry of degree one in the classical continuous version of the model. In this way, quantum chains endowed with a recursive structure can be identified from the properties of their classical relatives. The authors also show that in the quantum continuous limits of the XYZ model, the ladder property of the boost operator disappears. For the Hubbard model they demonstrate the nonexistence of a ladder operator. Nevertheless, the general structure of the conserved charges is indicated, and the expression for the terms linear in the model's free parameter for all charges is derived in closed form. 62 refs., 4 figs

  2. An unscaled parameter to measure the order of surfaces: a new surface elaboration to increase cells adhesion.

    Science.gov (United States)

    Bigerelle, M; Anselme, K; Dufresne, E; Hardouin, P; Iost, A

    2002-08-01

    We present a new parameter to quantify the order of a surface. This parameter is scale-independent and can be used to compare the organization of a surface at different scales of range and amplitude. To test the accuracy of this roughness parameter versus a hundred existing ones, we created an original statistical bootstrap method. In order to assess the physical relevance of this new parameter, we elaborated a great number of surfaces with various roughness amplitudes on titanium and titanium-based alloys using different physical processes. Then we studied the influence of the roughness amplitude on in vitro adhesion and proliferation of human osteoblasts. It was then shown that our new parameter best discriminates among the cell adhesion phenomena than others' parameters (Average roughness (Ra em leader )): cells adhere better on isotropic surfaces with a low order, provided this order is quantified on a scale that is more important than that of the cells. Additionally, on these low ordered metallic surfaces, the shape of the cells presents the same morphological aspect as that we can see on the human bone trabeculae. The method used to prepare these isotropic surfaces (electroerosion) could be undoubtedly and easily applied to prepare most biomaterials with complex geometries and to improve bone implant integration. Moreover, the new order parameter we developed may be particularly useful for the fundamental understanding of the mechanism of bone cell installation on a relief and of the formation of bone cell-material interface.

  3. Symmetry of order-parameters in high-Tc layered superconductors

    International Nuclear Information System (INIS)

    Rajagopal, A.K.; Jha, Sudhanshu S.

    1997-01-01

    It is well known that the anisotropy and wave-vector dependence of the energy-gap function determine many important properties of a superconductor which are relevant for device applications. Apart from a weak dependence on the wave-vector k - > in the direction perpendicular to the reciprocal layer-plane of a high-T c layered superconductor, it is shown that anisotropic superconducting order parameters for intra-layer pairing in the class of such materials with orthorhombic crystal structures, can have either pure s-wave like symmetry or mixed d-wave and anisotropic extended s-wave like symmetries in the reciprocal layer-plane. However, in such materials with tetragonal crystal structures, it is possible to have a pure s-wave like symmetry, which may be either isotropic or anisotropic in the layer k - >-space, or a pure d-wave like symmetry, as far the k - >-dependence in the reciprocal layer plane is concerned. In view of this, some suggestions for analysing experimental data will also be presented. (author)

  4. Short-Range Vital Signs Sensing Based on EEMD and CWT Using IR-UWB Radar

    Directory of Open Access Journals (Sweden)

    Xikun Hu

    2016-11-01

    Full Text Available The radar sensor described realizes healthcare monitoring capable of detecting subject chest-wall movement caused by cardiopulmonary activities and wirelessly estimating the respiration and heartbeat rates of the subject without attaching any devices to the body. Conventional single-tone Doppler radar can only capture Doppler signatures because of a lack of bandwidth information with noncontact sensors. In contrast, we take full advantage of impulse radio ultra-wideband (IR-UWB radar to achieve low power consumption and convenient portability, with a flexible detection range and desirable accuracy. A noise reduction method based on improved ensemble empirical mode decomposition (EEMD and a vital sign separation method based on the continuous-wavelet transform (CWT are proposed jointly to improve the signal-to-noise ratio (SNR in order to acquire accurate respiration and heartbeat rates. Experimental results illustrate that respiration and heartbeat signals can be extracted accurately under different conditions. This noncontact healthcare sensor system proves the commercial feasibility and considerable accessibility of using compact IR-UWB radar for emerging biomedical applications.

  5. Kinetic arrest and glass-glass transition in short-ranged attractive colloids

    International Nuclear Information System (INIS)

    Sztucki, M.; Narayanan, T.; Belina, G.; Moussaied, A.; Pignon, F.; Hoekstra, H.

    2006-01-01

    A thermally reversible repulsive hard-sphere to sticky-sphere transition was studied in a model colloidal system over a wide volume fraction range. The static microstructure was obtained from high resolution small angle x-ray scattering, the colloid dynamics was probed by dynamic x-ray and light scattering, and supplementary mechanical properties were derived from bulk rheology. At low concentration, the system shows features of gas-liquid type phase separation. The bulk phase separation is presumably interrupted by a gelation transition at the intermediate volume fraction range. At high volume fractions, fluid-attractive glass and repulsive glass-attractive glass transitions are observed. It is shown that the volume fraction of the particles can be reliably deduced from the absolute scattered intensity. The static structure factor is modeled in terms of an attractive square-well potential, using the leading order series expansion of Percus-Yevick approximation. The ensemble-averaged intermediate scattering function shows different levels of frozen components in the attractive and repulsive glassy states. The observed static and dynamic behavior are consistent with the predictions of a mode-coupling theory and numerical simulations for a square-well attractive system

  6. The quasi-classical limit of scattering amplitude - L2-approach for short range potentials

    International Nuclear Information System (INIS)

    Yajima, K.; Vienna Univ.

    1984-01-01

    We are concerned with the asymptotic behaviour as Planck's constant h → 0 of the scattering operator Ssup(h) associated with the pair of Schroedinger equations i h/2π delta u/delta t = - ((h/2π) 2 /2m)Δu + V(x) u equivalent to Hsup(h)u and i h/2π delta u/delta t = - ((h/2π) 2 /2m)Δu equivalent to Hsup(h) 0 u. We shall show under certain conditions that the scattering matrix S-circumflexsup(h)(p,q), the distribution kernel of Ssup(h) in momentum representation, may be expressed in terms of a Fourier integral operator. Then applying the stationary phase method to it, we shall prove that S-circumflexsup(h) has an asymptotic expansion in powers of h/2π up to any order in L 2 -space and that the limit as h → 0 of the total cross section is twice the one of classical mechanics, in generic. (Author)

  7. ℋ- adaptive observer design and parameter identification for a class of nonlinear fractional-order systems

    KAUST Repository

    Ndoye, Ibrahima; Voos, Holger; Laleg-Kirati, Taous-Meriem; Darouach, Mohamed

    2014-01-01

    In this paper, an adaptive observer design with parameter identification for a nonlinear system with external perturbations and unknown parameters is proposed. The states of the nonlinear system are estimated by a nonlinear observer and the unknown

  8. Nonlinear Parameter-Varying AeroServoElastic Reduced Order Model for Aerostructural Sensing and Control, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The overall goal of the project is to develop reliable reduced order modeling technologies to automatically generate parameter-varying (PV), aeroservoelastic (ASE)...

  9. Optimization of accelerator parameters using normal form methods on high-order transfer maps

    Energy Technology Data Exchange (ETDEWEB)

    Snopok, Pavel [Michigan State Univ., East Lansing, MI (United States)

    2007-05-01

    in a way that is easy to understand, such important characteristics as the strengths of the resonances and the tune shifts with amplitude and various parameters of the system are calculated. Each major section is supplied with the results of applying various numerical optimization methods to the problems stated. The emphasis is made on the efficiency comparison of various approaches and methods. The main simulation tool is the arbitrary order code COSY INFINITY written by M. Berz, K. Makino, et al. at Michigan State University. Also, the code MAD is utilized to design the 750 x 750 GeV Muon Collider storage ring baseline lattice.

  10. Generalizing the order and the parameters of macro-operators by explanation-based learning - Extension of Explanation-Based Learning on Partial Order

    International Nuclear Information System (INIS)

    Li, Huihua

    1992-01-01

    The traditional generalization methods such as FIKE's macro-operator learning and Explanation-Based Learning (EBL) deal with totally ordered plans. They generalize only the plan operators and the conditions under which the generalized plan can be applied in its initial total order, but not the partial order among operators in which the generalized plan can be successfully executed. In this paper, we extend the notion of the EBL on the partial order of plans. A new method is presented for learning, from a totally or partially ordered plan, partially ordered macro-operators (generalized plans) each of which requires a set of the weakest conditions for its reuse. It is also valuable for generalizing partially ordered plans. The operators are generalized in the FIKE's triangle table. We introduce the domain axioms to generate the constraints for the consistency of generalized states. After completing the triangle table with the information concerning the operator destructions (interactions), we obtain the global explanation of the partial order on the operators. Then, we represent all the necessary ordering relations by a directed graph. The exploitation of this graph permits to explicate the dependence between the partial orders and the constraints among the parameters of generalized operators, and allows all the solutions to be obtained. (author) [fr

  11. Crystal nucleation in binary hard-sphere mixtures: the effect of order parameter on the cluster composition

    NARCIS (Netherlands)

    Ni, R.; Smallenburg, F.; Filion, L.C.; Dijkstra, M.

    2011-01-01

    We study crystal nucleation in a binary mixture of hard spheres and investigate the composition and size of the (non)critical clusters using Monte Carlo simulations. In order to study nucleation of a crystal phase in computer simulations, a one-dimensional order parameter is usually defined to

  12. ℋ- adaptive observer design and parameter identification for a class of nonlinear fractional-order systems

    KAUST Repository

    Ndoye, Ibrahima

    2014-12-01

    In this paper, an adaptive observer design with parameter identification for a nonlinear system with external perturbations and unknown parameters is proposed. The states of the nonlinear system are estimated by a nonlinear observer and the unknown parameters are also adapted to their values. Sufficient conditions for the stability of the adaptive observer error dynamics are derived in terms of linear matrix inequalities. Simulation results for chaotic Lorenz systems with unknown parameters in the presence of external perturbations are given to illustrate the effectiveness of our proposed approach. © 2014 IEEE.

  13. Assessment of oscillator strengths with multiconfigurational short-range density functional theory for electronic excitations in organic molecules

    DEFF Research Database (Denmark)

    Hedegård, Erik Donovan

    2017-01-01

    considered the large collection of organic molecules whose excited states were investigated with a range of electronic structure methods by Thiel et al. As a by-product of our calculations of oscillator strengths, we also obtain electronic excitation energies, which enable us to compare the performance......We have in a series of recent papers investigated electronic excited states with a hybrid between a complete active space self-consistent field (CASSCF) wave function and density functional theory (DFT). This method has been dubbed the CAS short-range DFT method (CAS–srDFT). The previous papers...

  14. A short-range weather prediction system for South Africa based on a multi-model approach

    CSIR Research Space (South Africa)

    Landman, S

    2012-10-01

    Full Text Available stream_source_info Landman5_2012.pdf.txt stream_content_type text/plain stream_size 44898 Content-Encoding ISO-8859-1 stream_name Landman5_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 1 A short... to be skillful. Moreover, the system outscores the forecast skill of the individual models. Keywords: short-range, ensemble, forecasting, precipitation, multi-model, verification Tel: +27 12 367 6054...

  15. Mean-Field Theory of Electrical Double Layer In Ionic Liquids with Account of Short-Range Correlations

    International Nuclear Information System (INIS)

    Goodwin, Zachary A.H.; Feng, Guang; Kornyshev, Alexei A.

    2017-01-01

    We develop the theory of the electrical double layer in ionic liquids as proposed earlier by Kornyshev (2007). In the free energy function we keep the so called ‘short-range correlation terms’ which were omitted there. With some simplifying assumptions, we arrive at a modified expression for differential capacitance, which makes differential capacitance curves less sharply depending on electrode potential and having smaller values at extrema than in the previous theory. This brings the results closer to typical experimental observations, and makes it appealing to use this formalism for treatment of experimental data. Implications on Debye length and the extent of ion paring in ionic liquids are then briefly discussed.

  16. On the analysis of glow curves with the general order kinetics: Reliability of the computed trap parameters

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, F. [Facultad de Ingeniería (UNCPBA) and CIFICEN (UNCPBA – CICPBA – CONICET), Av. del Valle 5737, 7400 Olavarría (Argentina); Santiago, M.; Martinez, N.; Marcazzó, J.; Molina, P.; Caselli, E. [Instituto de Física Arroyo Seco (UNCPBA) and CIFICEN (UNCPBA – CICPBA – CONICET), Pinto 399, 7000 Tandil (Argentina)

    2017-04-15

    Nowadays the most employed kinetics for analyzing glow curves is the general order kinetics (GO) proposed by C. E. May and J. A. Partridge. As shown in many articles this kinetics might yield wrong parameters characterizing trap and recombination centers. In this article this kinetics is compared with the modified general order kinetics put forward by M. S. Rasheedy by analyzing synthetic glow curves. The results show that the modified kinetics gives parameters, which are more accurate than that yield by the original general order kinetics. A criterion is reported to evaluate the accuracy of the trap parameters found by deconvolving glow curves. This criterion was employed to assess the reliability of the trap parameters of the YVO{sub 4}: Eu{sup 3+} compounds.

  17. Modulating functions method for parameters estimation in the fifth order KdV equation

    KAUST Repository

    Asiri, Sharefa M.; Liu, Da-Yan; Laleg-Kirati, Taous-Meriem

    2017-01-01

    In this work, the modulating functions method is proposed for estimating coefficients in higher-order nonlinear partial differential equation which is the fifth order Kortewegde Vries (KdV) equation. The proposed method transforms the problem into a

  18. High-order dynamic modeling and parameter identification of structural discontinuities in Timoshenko beams by using reflection coefficients

    Science.gov (United States)

    Fan, Qiang; Huang, Zhenyu; Zhang, Bing; Chen, Dayue

    2013-02-01

    Properties of discontinuities, such as bolt joints and cracks in the waveguide structures, are difficult to evaluate by either analytical or numerical methods due to the complexity and uncertainty of the discontinuities. In this paper, the discontinuity in a Timoshenko beam is modeled with high-order parameters and then these parameters are identified by using reflection coefficients at the discontinuity. The high-order model is composed of several one-order sub-models in series and each sub-model consists of inertia, stiffness and damping components in parallel. The order of the discontinuity model is determined based on the characteristics of the reflection coefficient curve and the accuracy requirement of the dynamic modeling. The model parameters are identified through the least-square fitting iteration method, of which the undetermined model parameters are updated in iteration to fit the dynamic reflection coefficient curve with the wave-based one. By using the spectral super-element method (SSEM), simulation cases, including one-order discontinuities on infinite- and finite-beams and a two-order discontinuity on an infinite beam, were employed to evaluate both the accuracy of the discontinuity model and the effectiveness of the identification method. For practical considerations, effects of measurement noise on the discontinuity parameter identification are investigated by adding different levels of noise to the simulated data. The simulation results were then validated by the corresponding experiments. Both the simulation and experimental results show that (1) the one-order discontinuities can be identified accurately with the maximum errors of 6.8% and 8.7%, respectively; (2) and the high-order discontinuities can be identified with the maximum errors of 15.8% and 16.2%, respectively; and (3) the high-order model can predict the complex discontinuity much more accurately than the one-order discontinuity model.

  19. Modeling Short-Range Soil Variability and its Potential Use in Variable-Rate Treatment of Experimental Plots

    Directory of Open Access Journals (Sweden)

    A Moameni

    2011-02-01

    Full Text Available Abstract In Iran, the experimental plots under fertilizer trials are managed in such a way that the whole plot area uniformly receives agricultural inputs. This could lead to biased research results and hence to suppressing of the efforts made by the researchers. This research was conducted in a selected site belonging to the Gonbad Agricultural Research Station, located in the semiarid region, northeastern Iran. The aim was to characterize the short-range spatial variability of the inherent and management-depended soil properties and to determine if this variation is large and can be managed at practical scales. The soils were sampled using a grid 55 m apart. In total, 100 composite soil samples were collected from topsoil (0-30 cm and were analyzed for calcium carbonate equivalent, organic carbon, clay, available phosphorus, available potassium, iron, copper, zinc and manganese. Descriptive statistics were applied to check data trends. Geostatistical analysis was applied to variography, model fitting and contour mapping. Sampling at 55 m made it possible to split the area of the selected experimental plot into relatively uniform areas that allow application of agricultural inputs with variable rates. Keywords: Short-range soil variability, Within-field soil variability, Interpolation, Precision agriculture, Geostatistics

  20. Decreased long- and short-range functional connectivity at rest in drug-naive major depressive disorder.

    Science.gov (United States)

    Guo, Wenbin; Liu, Feng; Chen, Jindong; Wu, Renrong; Zhang, Zhikun; Yu, Miaoyu; Xue, Zhimin; Zhao, Jingping

    2016-08-01

    Abnormal functional connectivity has been observed in major depressive disorder. Anatomical distance may affect functional connectivity in patients with major depressive disorder. However, whether and how anatomical distance affects functional connectivity at rest remains unclear in drug-naive patients with major depressive disorder. Forty-four patients with major depressive disorder, as well as 44 age-, sex- and education-matched healthy controls, underwent resting-state functional magnetic resonance imaging scanning. Regional functional connectivity strength was calculated for each voxel in the whole brain, which was further divided into short- and long-range functional connectivity strength. The patients showed decreased long-range positive functional connectivity strength in the right inferior parietal lobule, as well as decreased short-range positive functional connectivity strength in the right insula and right superior temporal gyrus relative to those of the controls. No significant correlations existed between abnormal functional connectivity strength and the clinical variables of the patients. The findings revealed that anatomical distance decreases long- and short-range functional connectivity strength in patients with major depressive disorder, which may underlie the neurobiology of major depressive disorder. © The Royal Australian and New Zealand College of Psychiatrists 2015.

  1. Model-order reduction of lumped parameter systems via fractional calculus

    Science.gov (United States)

    Hollkamp, John P.; Sen, Mihir; Semperlotti, Fabio

    2018-04-01

    This study investigates the use of fractional order differential models to simulate the dynamic response of non-homogeneous discrete systems and to achieve efficient and accurate model order reduction. The traditional integer order approach to the simulation of non-homogeneous systems dictates the use of numerical solutions and often imposes stringent compromises between accuracy and computational performance. Fractional calculus provides an alternative approach where complex dynamical systems can be modeled with compact fractional equations that not only can still guarantee analytical solutions, but can also enable high levels of order reduction without compromising on accuracy. Different approaches are explored in order to transform the integer order model into a reduced order fractional model able to match the dynamic response of the initial system. Analytical and numerical results show that, under certain conditions, an exact match is possible and the resulting fractional differential models have both a complex and frequency-dependent order of the differential operator. The implications of this type of approach for both model order reduction and model synthesis are discussed.

  2. On the number of free energy extremums of a solid solution with two long-range order parameters

    International Nuclear Information System (INIS)

    Dateshidze, N.A.; Ratishvili, I.G.

    1977-01-01

    The free energy of ordering f.c.c. lattice solid solution is investigated. The ordering is regarded as homogeneous in the whole bulk of the crystal (i.e. resistant towards formation of antiphase domains). It is described by one of the appropriate distribution functions which contains two long-range order parameters. The calculations have revealed the extrema of the free energy function, and their shape and behaviour upon variations of temperature are analyzed. It is shown that under certain circumstances the system can display more than one minimum of free energy within the ordered phase

  3. Inadmissibility of Usual and Mixed Estimators of Two Ordered Gamma Scale Parameters Under Reflected Gamma Loss Function

    Directory of Open Access Journals (Sweden)

    Z. Meghnatisi

    2009-06-01

    Full Text Available Let Xi1, · · · , Xini be a random sample from a gamma distribution with known shape parameter νi > 0 and unknown scale parameter βi > 0, i = 1, 2, satisfying 0 < β1 6 β2. We consider the class of mixed estimators for estimation of β1 and β2 under reflected gamma loss function. It has been shown that the minimum risk equivariant estimator of βi, i = 1, 2, which is admissible when no information on the ordering of parameters are given, is inadmissible and dominated by a class of mixed estimators when it is known that the parameters are ordered. Also, the inadmissible estimators in the class of mixed estimators are derived. Finally the results are extended to some subclass of exponential family

  4. Investigate the effect of anisotropic order parameter on the specific heat of anisotropic two-band superconductors

    International Nuclear Information System (INIS)

    Udomsamuthirun, P.; Peamsuwan, R.; Kumvongsa, C.

    2009-01-01

    The effect of anisotropic order parameter on the specific heat of anisotropic two-band superconductors in BCS weak-coupling limit is investigated. An analytical specific heat jump and the numerical specific heat are shown by using anisotropic order parameters, and the electron-phonon interaction and non-electron-phonon interaction. The two models of anisotropic order parameters are used for numerical calculation that we find little effect on the numerical results. The specific heat jump of MgB 2 , Lu 2 Fe 3 Si 5 and Nb 3 Sn superconductors can fit well with both of them. By comparing the experimental data with overall range of temperature, the best fit is Nb 3 Sn, MgB 2 , and Lu 2 Fe 3 Si 5 superconductors.

  5. Macroscopically constrained Wang-Landau method for systems with multiple order parameters and its application to drawing complex phase diagrams

    Science.gov (United States)

    Chan, C. H.; Brown, G.; Rikvold, P. A.

    2017-05-01

    A generalized approach to Wang-Landau simulations, macroscopically constrained Wang-Landau, is proposed to simulate the density of states of a system with multiple macroscopic order parameters. The method breaks a multidimensional random-walk process in phase space into many separate, one-dimensional random-walk processes in well-defined subspaces. Each of these random walks is constrained to a different set of values of the macroscopic order parameters. When the multivariable density of states is obtained for one set of values of fieldlike model parameters, the density of states for any other values of these parameters can be obtained by a simple transformation of the total system energy. All thermodynamic quantities of the system can then be rapidly calculated at any point in the phase diagram. We demonstrate how to use the multivariable density of states to draw the phase diagram, as well as order-parameter probability distributions at specific phase points, for a model spin-crossover material: an antiferromagnetic Ising model with ferromagnetic long-range interactions. The fieldlike parameters in this model are an effective magnetic field and the strength of the long-range interaction.

  6. On the motion of non-linear oscillators with a fractional-order restoring force and time variable parameters

    International Nuclear Information System (INIS)

    Kovacic, Ivana

    2009-01-01

    An analytical approach to determine the approximate solution for the periodic motion of non-conservative oscillators with a fractional-order restoring force and slowly varying parameters is presented. The solution has the form of the first-order differential equation for the amplitude and phase of motion. The method used is based on the combination of the Krylov-Bogoliubov method with Hamilton's variational principle with the uncommutative rule for the variation of velocity. The conservative systems with slowly varying parameters are also considered. The corresponding adiabatic invariant is obtained. Two examples are given to illustrate derived theoretical results.

  7. Two-order parameters theory of the metal-insulator phase transition kinetics in the magnetic field

    Science.gov (United States)

    Dubovskii, L. B.

    2018-05-01

    The metal-insulator phase transition is considered within the framework of the Ginzburg-Landau approach for the phase transition described with two coupled order parameters. One of the order parameters is the mass density which variation is responsible for the origin of nonzero overlapping of the two different electron bands and the appearance of free electron carriers. This transition is assumed to be a first-order phase one. The free electron carriers are described with the vector-function representing the second-order parameter responsible for the continuous phase transition. This order parameter determines mostly the physical properties of the metal-insulator transition and leads to a singularity of the surface tension at the metal-insulator interface. The magnetic field is involved into the consideration of the system. The magnetic field leads to new singularities of the surface tension at the metal-insulator interface and results in a drastic variation of the phase transition kinetics. A strong singularity in the surface tension results from the Landau diamagnetism and determines anomalous features of the metal-insulator transition kinetics.

  8. Inadmissibility of Usual and Mixed Estimators of Two Ordered Gamma Scale Parameters Under Reflected Gamma Loss Function

    OpenAIRE

    Z. Meghnatisi; N. Nematollahi

    2009-01-01

    Let Xi1, · · · , Xini be a random sample from a gamma distribution with known shape parameter νi > 0 and unknown scale parameter βi > 0, i = 1, 2, satisfying 0 < β1 6 β2. We consider the class of mixed estimators for estimation of β1 and β2 under reflected gamma loss function. It has been shown that the minimum risk equivariant estimator of βi, i = 1, 2, which is admissible when no information on the ordering of parameters are given, is inadmissible and dominated by a cla...

  9. On the parameter estimation of first order IMA model corrupted with ...

    African Journals Online (AJOL)

    In this paper, we showed how the autocovariance functions can be used to estimate the true parameters of IMA(1) models corrupted with white noise . We performed simulation studies to demonstrate our findings. The simulation studies showed that under the presence of errors in not more than 30% of total data points, our ...

  10. Digital predistortion of 75–110 GHz W-band frequency multiplier for fiber wireless short range access systems

    DEFF Research Database (Denmark)

    Zhao, Ying; Deng, Lei; Pang, Xiaodan

    2011-01-01

    be effectively pre-compensated. Without using costly W-band components, a transmission system with 26km fiber and 4m wireless transmission operating at 99.6GHz is experimentally validated. Adjacent-channel power ratio (ACPR) improvements for IQ-modulated vector signals are guaranteed and transmission......We present a W-band fiber-wireless transmission system based on a nonlinear frequency multiplier for high-speed wireless short range access applications. By implementing a baseband digital signal predistortion scheme, intensive nonlinear distortions induced in a sextuple frequency multiplier can...... performances for fiber and wireless channels are studied. This W-band predistortion technique is a promising candidate for applications in high capacity wireless-fiber access systems....

  11. One-level modeling for diagnosing surface winds over complex terrain. II - Applicability to short-range forecasting

    Science.gov (United States)

    Alpert, P.; Getenio, B.; Zak-Rosenthal, R.

    1988-01-01

    The Alpert and Getenio (1988) modification of the Mass and Dempsey (1985) one-level sigma-surface model was used to study four synoptic events that included two winter cases (a Cyprus low and a Siberian high) and two summer cases. Results of statistical verification showed that the model is not only capable of diagnosing many details of surface mesoscale flow, but might also be useful for various applications which require operative short-range prediction of the diurnal changes of high-resolution surface flow over complex terrain, for example, in locating wildland fires, determining the dispersion of air pollutants, and predicting changes in wind energy or of surface wind for low-level air flights.

  12. Role of long- and short-range hydrophobic, hydrophilic and charged residues contact network in protein’s structural organization

    Directory of Open Access Journals (Sweden)

    Sengupta Dhriti

    2012-06-01

    Full Text Available Abstract Background The three-dimensional structure of a protein can be described as a graph where nodes represent residues and the strength of non-covalent interactions between them are edges. These protein contact networks can be separated into long and short-range interactions networks depending on the positions of amino acids in primary structure. Long-range interactions play a distinct role in determining the tertiary structure of a protein while short-range interactions could largely contribute to the secondary structure formations. In addition, physico chemical properties and the linear arrangement of amino acids of the primary structure of a protein determines its three dimensional structure. Here, we present an extensive analysis of protein contact subnetworks based on the London van der Waals interactions of amino acids at different length scales. We further subdivided those networks in hydrophobic, hydrophilic and charged residues networks and have tried to correlate their influence in the overall topology and organization of a protein. Results The largest connected component (LCC of long (LRN-, short (SRN- and all-range (ARN networks within proteins exhibit a transition behaviour when plotted against different interaction strengths of edges among amino acid nodes. While short-range networks having chain like structures exhibit highly cooperative transition; long- and all-range networks, which are more similar to each other, have non-chain like structures and show less cooperativity. Further, the hydrophobic residues subnetworks in long- and all-range networks have similar transition behaviours with all residues all-range networks, but the hydrophilic and charged residues networks don’t. While the nature of transitions of LCC’s sizes is same in SRNs for thermophiles and mesophiles, there exists a clear difference in LRNs. The presence of larger size of interconnected long-range interactions in thermophiles than mesophiles, even at

  13. Short-Range Temporal Interactions in Sleep; Hippocampal Spike Avalanches Support a Large Milieu of Sequential Activity Including Replay.

    Directory of Open Access Journals (Sweden)

    J Matthew Mahoney

    Full Text Available Hippocampal neural systems consolidate multiple complex behaviors into memory. However, the temporal structure of neural firing supporting complex memory consolidation is unknown. Replay of hippocampal place cells during sleep supports the view that a simple repetitive behavior modifies sleep firing dynamics, but does not explain how multiple episodes could be integrated into associative networks for recollection during future cognition. Here we decode sequential firing structure within spike avalanches of all pyramidal cells recorded in sleeping rats after running in a circular track. We find that short sequences that combine into multiple long sequences capture the majority of the sequential structure during sleep, including replay of hippocampal place cells. The ensemble, however, is not optimized for maximally producing the behavior-enriched episode. Thus behavioral programming of sequential correlations occurs at the level of short-range interactions, not whole behavioral sequences and these short sequences are assembled into a large and complex milieu that could support complex memory consolidation.

  14. Change in the order parameter of a superconductor of type I in the presence of magnetic dipoles

    International Nuclear Information System (INIS)

    Lebeau, C.; Pinel, J.

    1977-01-01

    Taking the order parameter to be spatially constant, we show that magnetic dipoles modify the energy with a term proportional to the difference between the local fields in the normal and supercondcuting states. Evaluation of this difference predicts a second-order transition. The transition temperature only depends on the mean value of ferromagnetic magnetisation. Specific heat and susceptibility measurements made on HgFe are compared with this model [fr

  15. Analysis of long- and short-range contribution to adhesion work in cardiac fibroblasts: An atomic force microscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Sbaizero, O., E-mail: sbaizero@units.it [Department of Engineering and Architecture, University of Trieste (Italy); University of Colorado Cardiovascular Institute, University of Colorado Denver, Aurora (United States); DelFavero, G. [Department of Engineering and Architecture, University of Trieste (Italy); Martinelli, V. [International Center for Genetic Engineering and Biotechnology, Trieste (Italy); Long, C.S.; Mestroni, L. [University of Colorado Cardiovascular Institute, University of Colorado Denver, Aurora (United States)

    2015-04-01

    Atomic force microscopy (AFM) for single-cell force spectroscopy (SCFS) and Poisson statistic were used to analyze the detachment work recorded during the removal of gold-covered microspheres from cardiac fibroblasts. The effect of Cytochalasin D, a disruptor of the actin cytoskeleton, on cell adhesion was also tested. The adhesion work was assessed using a Poisson analysis also derived from single-cell force spectroscopy retracting curves. The use of Poisson analysis to get adhesion work from AFM curves is quite a novel method, and in this case, proved to be effective to study the short-range and long-range contributions to the adhesion work. This method avoids the difficult identification of minor peaks in the AFM retracting curves by creating what can be considered an average adhesion work. Even though the effect of actin depolymerisation is well documented, its use revealed that control cardiac fibroblasts (CT) exhibit a work of adhesion at least 5 times higher than that of the Cytochalasin treated cells. However, our results indicate that in both cells short-range and long-range contributions to the adhesion work are nearly equal and the same heterogeneity index describes both cells. Therefore, we infer that the different adhesion behaviors might be explained by the presence of fewer membrane adhesion molecules available at the AFM tip–cell interface under circumstances where the actin cytoskeleton has been disrupted. - Highlights: • AFM force–deformation curve was used to characterize the cardiac fibroblast adhesion behavior. • The amount and nature of adhesion were assessed using a Poisson analysis applied to the AFM curve. • The work of adhesion for control cells was about four times higher than that of the Cyt-D treated cells. • Short- and long-range contributions to adhesion are nearly equal for both control and treated cells.

  16. Numerical solution of second-order stochastic differential equations with Gaussian random parameters

    Directory of Open Access Journals (Sweden)

    Rahman Farnoosh

    2014-07-01

    Full Text Available In this paper, we present the numerical solution of ordinary differential equations (or SDEs, from each orderespecially second-order with time-varying and Gaussian random coefficients. We indicate a complete analysisfor second-order equations in specially case of scalar linear second-order equations (damped harmonicoscillators with additive or multiplicative noises. Making stochastic differential equations system from thisequation, it could be approximated or solved numerically by different numerical methods. In the case oflinear stochastic differential equations system by Computing fundamental matrix of this system, it could becalculated based on the exact solution of this system. Finally, this stochastic equation is solved by numericallymethod like E.M. and Milstein. Also its Asymptotic stability and statistical concepts like expectationand variance of solutions are discussed.

  17. Higher order corrections to Higgs boson decays in the MSSM with complex parameters

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Karina E. [Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Rzehak, Heidi [Freiburg Univ. (Germany). Physikalisches Inst.; Weiglein, Georg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2011-03-15

    We discuss Higgs boson decays in the CP-violating MSSM, and examine their phe- nomenological impact using cross section limits from the LEP Higgs searches. This includes a discussion of the full 1-loop results for the partial decay widths of neutral Higgs bosons into lighter neutral Higgs bosons (h{sub a}{yields}h{sub b}h{sub c}) and of neutral Higgs bosons into fermions (h{sub a}{yields}f anti f). In calculating the genuine vertex corrections, we take into account the full spectrum of supersymmetric particles and all complex phases of the supersymmetric parameters. These genuine vertex corrections are supplemented with Higgs propagator corrections incorporating the full one-loop and the dominant two-loop contributions, and we illustrate a method of consistently treating diagrams involving mixing with Goldstone and Z bosons. In particular, the genuine vertex corrections to the process h{sub a}{yields}h{sub b}h{sub c} are found to be very large and, where this process is kinematically allowed, can have a significant effect on the regions of the CPX bench- mark scenario which can be excluded by the results of the Higgs searches at LEP. However, there remains an unexcluded region of CPX parameter space at a lightest neutral Higgs boson mass of {proportional_to}45 GeV. In the analysis, we pay particular attention to the conversion between parameters defined in different renormalisation schemes and are therefore able to make a comparison to the results found using renormalisation group improved/effective potential calculations. (orig.)

  18. Understanding agent-based models of financial markets: A bottom-up approach based on order parameters and phase diagrams

    Science.gov (United States)

    Lye, Ribin; Tan, James Peng Lung; Cheong, Siew Ann

    2012-11-01

    We describe a bottom-up framework, based on the identification of appropriate order parameters and determination of phase diagrams, for understanding progressively refined agent-based models and simulations of financial markets. We illustrate this framework by starting with a deterministic toy model, whereby N independent traders buy and sell M stocks through an order book that acts as a clearing house. The price of a stock increases whenever it is bought and decreases whenever it is sold. Price changes are updated by the order book before the next transaction takes place. In this deterministic model, all traders based their buy decisions on a call utility function, and all their sell decisions on a put utility function. We then make the agent-based model more realistic, by either having a fraction fb of traders buy a random stock on offer, or a fraction fs of traders sell a random stock in their portfolio. Based on our simulations, we find that it is possible to identify useful order parameters from the steady-state price distributions of all three models. Using these order parameters as a guide, we find three phases: (i) the dead market; (ii) the boom market; and (iii) the jammed market in the phase diagram of the deterministic model. Comparing the phase diagrams of the stochastic models against that of the deterministic model, we realize that the primary effect of stochasticity is to eliminate the dead market phase.

  19. Search for a spin-dependent short-range force between nucleons with a 3He/129Xe clock-comparison experiment

    International Nuclear Information System (INIS)

    Tullney, Kathlynne

    2014-01-01

    The standard model (SM) of particle physics describes all known particles and their interactions. However, the SM leaves many issues unresolved. For example, it only includes three of the four fundamental forces and does not clarify the question why in the strong interaction CP symmetry is violated due to its non-trivial vacuum structure is predicted (Θ-term), but experimentally unverifiable. The latter one is known as the strong CP-problem of quantum chromodynamics (QCD) and is solved by the Peccei-Quinn-Weinberg-Wilczek theory. This theory predicts a new and almost massless boson which is known as the axion. The axion feebly interacts with matter and therefore it is a good candidate for cold dark matter, too. Axions are produced by the Primakoff-effect, i.e. by conversion of photons which are scattered in the electromagnetic field, e.g. of atoms. The inverse Primakoff-effect, which converts axions to photons again, can be used for direct detection of galactic, solar, or laboratory axions. Cosmological and astrophysical observations constrain the mass of the axion from a few μeV to some meV (''axion mass window''). If the axion exists, then it mediates a CP violating, spin-dependent, short-range interaction between a fermion and the spin of another fermion. By verification of this interaction, the axion can be detected indirectly. In the framework of the present thesis an experiment to search for this spindependent short-range interaction was performed in the magnetically shielded room BMSR-2 of the Physikalisch-Technische Bundesanstalt Berlin. An ultra-sensitive low-field co-magnetometer was employed which is based on the detection of free precession of 3 He and 129 Xe nuclear spins using SQUIDs as low-noise magnetic flux detectors. The two nuclear spin polarized gases are filled into a glass cell which is immersed in a low magnetic field of about B 0 = 0.35 μT with absolute field gradients in the order of pT/cm. The spin precession frequencies of 3 He and 129

  20. Choosing order of operations to accelerate strip structure analysis in parameter range

    Science.gov (United States)

    Kuksenko, S. P.; Akhunov, R. R.; Gazizov, T. R.

    2018-05-01

    The paper considers the issue of using iteration methods in solving the sequence of linear algebraic systems obtained in quasistatic analysis of strip structures with the method of moments. Using the analysis of 4 strip structures, the authors have proved that additional acceleration (up to 2.21 times) of the iterative process can be obtained during the process of solving linear systems repeatedly by means of choosing a proper order of operations and a preconditioner. The obtained results can be used to accelerate the process of computer-aided design of various strip structures. The choice of the order of operations to accelerate the process is quite simple, universal and could be used not only for strip structure analysis but also for a wide range of computational problems.

  1. Influence of nonstoichiometry and ordering on basic structure parameter of cubic titanium carbide

    International Nuclear Information System (INIS)

    Zueva, L.V.; Gusev, A.I.

    1999-01-01

    Effect of nonstoichiometry and phase transformations of the disorder-order type on the basis (B1 type) structure period of TiC y (0.5 y titanium carbide with formation of the Ti 2 C and Ti 3 C 2 superstructures leads to growth of the basic crystal lattice period as compared to disordered carbide. The problem on trends in static atomic displacement near vacancy is discussed with an account of the lattice period change [ru

  2. Topological network entanglement as order parameter for the emergence of geometry

    International Nuclear Information System (INIS)

    Diamantini, M Cristina; Trugenberger, Carlo A

    2017-01-01

    We show that, in discrete models of quantum gravity, emergent geometric space can be viewed as the entanglement pattern in a mixed quantum state of the ‘universe’, characterized by a universal topological network entanglement. As a concrete example we analyze the recently proposed model in which geometry emerges due to the condensation of 4-cycles in random regular bipartite graphs, driven by the combinatorial Ollivier–Ricci curvature. Using this model we show that the emergence of geometric order decreases the entanglement entropy of random configurations. The lowest geometric entanglement entropy is realized in four dimensions. (paper)

  3. Analytical Expressions for the Mixed-Order Kinetics Parameters of TL Glow Peaks Based on the two Heating Rates Method.

    Science.gov (United States)

    Maghrabi, Mufeed; Al-Abdullah, Tariq; Khattari, Ziad

    2018-03-24

    The two heating rates method (originally developed for first-order glow peaks) was used for the first time to evaluate the activation energy (E) from glow peaks obeying mixed-order (MO) kinetics. The derived expression for E has an insignificant additional term (on the scale of a few meV) when compared with the first-order case. Hence, the original expression for E using the two heating rates method can be used with excellent accuracy in the case of MO glow peaks. In addition, we derived a simple analytical expression for the MO parameter. The present procedure has the advantage that the MO parameter can now be evaluated using analytical expression instead of using the graphical representation between the geometrical factor and the MO parameter as given by the existing peak shape methods. The applicability of the derived expressions for real samples was demonstrated for the glow curve of Li 2 B 4 O 7 :Mn single crystal. The obtained parameters compare very well with those obtained by glow curve fitting and with the available published data.

  4. The order parameter equations of superfluid Fermi-liquid with spin-triplet pairing near Tc in magnetic field

    International Nuclear Information System (INIS)

    Tarasov, A.N.

    1995-01-01

    The article is devoted to description of equilibrium properties of superfluid phases of 3 He in magnetic field at temperatures near the normal-superfluid point T c . The Landau Fermi-liquid (F-L) approach generalized to superfluid Fermi-liquids (SFLs) is used. Equations for the order parameter paramagnetic SFL with spin-triplet pairing in static and uniform (DC) moderately strong magnetic field are derived without taking into account strong-coupling (SC) effects. An integro-differential equation is deduced for the order parameter in the general case of spin-triplet pairing (spin of a pair is s = 1, orbital moment l of a pair is any odd number). It is valid in the approximation of small space inhomogeneities of the SFL for external DC magnetic field at temperatures near T c . In the case of spin-triplet p-wave pairing a Ginzburg-Landau (GL) equation is derived for the order parameter A αj (complex 3 x 3 matrix). Corrections to the coefficients in the GL eq. are resulted from taking into account the influence of moderately strong DC magnetic field and spin-exchange F-L interaction by the theory of permutations. In such fields these corrections can be of the same order of magnitude as the so-called > SC corrections to the GL eq. (or even exceed them) and are much higher than the particle-hole asymmetric contribution. The above corrections are connected with deformation of the order parameter in moderate magnetic fields and are of interest at description of 3 He - B at low pressures

  5. Investigations of coal ignition in a short-range flame burner using optical measuring systems; Untersuchungen zur Kohlezuendung am Flachflammenbrenner unter Verwendung optischer Messtechnik

    Energy Technology Data Exchange (ETDEWEB)

    Hackert, G.; Kremer, H.; Wirtz, S. [Bochum Univ. (Germany). Lehrstuhl fuer Energieanlagentechnik

    1999-09-01

    The short-range flame burner and the KOALA reactor of DMT are experimental facilities for realistic simulation of coal conversion processes at high temperatures and pressures in atmospheric conditions. The TOSCA system enable measurements of temperatures, sizes, shapes and velocities of the fuel particles, which serve as a basis for a three-dimensional simulation model of coal combustion. In the future, further parameter studies will deepen the present knowledge of coal dust combustion under pressure and enable optimisation of the numerical models for simulation of industrial-scale systems for coal dust combustion under pressure. [Deutsch] Mit dem Flachflammenbrenner und dem KOALA-Reaktor der DMT stehen Versuchsapparaturen zur Verfuegung, mit deren Hilfe die Kohleumwandlungsprozesse bei hohen Temperaturen unter Druck und unter atmosphaerischen Bedingungen realistisch wiedergegeben werden. Das TOSCA-System erlaubt dabei die Bestimmung von Temperaturen, Groessen, Formen und Geschwindigkeiten der Brennstoffpartikel. Diese Daten liefern die Grundlage fuer die Erstellung eines dreidimensionalen Simulationsmodells zur Modellierung der Kohleverbrennung. In Zukunft werden weitere Parameterstudien das Verstaendnis der Kohlenstaubdruckverbrennung vertiefen und ein Optimierung der numerischen Modelle ermoeglichen, so dass die Simulation grosstechnischer Kohlenstaubdruckverbrennungsanlagen realisiert werden kann. (orig.)

  6. Josephson scanning tunneling microscopy -- a local and direct probe of the superconducting order parameter

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Hikari; Dynes, Robert; Barber Jr., Richard. P.; Ono, S.; Ando, Y.

    2009-09-01

    Direct measurements of the superconducting superfluid on the surface of vacuum-cleaved Bi2Sr2CaCu2O8+delta (BSCCO) samples are reported. These measurements are accomplished via Josephson tunneling into the sample using a novel scanning tunneling microscope (STM) equipped with a superconducting tip. The spatial resolution of the STM of lateral distances less than the superconducting coherence length allows it to reveal local inhomogeneities in the pair wavefunction of the BSCCO. Instrument performance is demonstrated first with Josephson measurements of Pb films followed by the layered superconductor NbSe2. The relevant measurement parameter, the Josephson ICRN product, is discussed within the context of both BCS superconductors and the high transition temperature superconductors. The local relationship between the ICRN product and the quasiparticle density of states (DOS) gap are presented within the context of phase diagrams for BSCCO. Excessive current densities can be produced with these measurements and have been found to alter the local DOS in the BSCCO. Systematic studies of this effect were performed to determine the practical measurement limits for these experiments. Alternative methods for preparation of the BSCCO surface are also discussed.

  7. Analog Circuit Design Low Voltage Low Power; Short Range Wireless Front-Ends; Power Management and DC-DC

    CERN Document Server

    Roermund, Arthur; Baschirotto, Andrea

    2012-01-01

    The book contains the contribution of 18 tutorials of the 20th workshop on Advances in Analog Circuit Design.  Each part discusses a specific to-date topic on new and valuable design ideas in the area of analog circuit design. Each part is presented by six experts in that field and state of the art information is shared and overviewed. This book is number 20 in this successful series of Analog Circuit Design, providing valuable information and excellent overviews of Low-Voltage Low-Power Data Converters - Chaired by Prof. Anderea Baschirotto, University of Milan-Bicocca Short Range Wireless Front-Ends - Chaired by Prof. Arthur van Roermund, Eindhoven University of Technology Power management and DC-DC - Chaired by Prof. M. Steyaert, Katholieke University Leuven Analog Circuit Design is an essential reference source for analog circuit designers and researchers wishing to keep abreast with the latest development in the field. The tutorial coverage also makes it suitable for use in an advanced design.

  8. Development and Short-Range Testing of a 100 kW Side-Illuminated Millimeter-Wave Thermal Rocket

    Science.gov (United States)

    Bruccoleri, Alexander; Eilers, James A.; Lambot, Thomas; Parkin, Kevin

    2015-01-01

    The objective of the phase described here of the Millimeter-Wave Thermal Launch System (MTLS) Project was to launch a small thermal rocket into the air using millimeter waves. The preliminary results of the first MTLS flight vehicle launches are presented in this work. The design and construction of a small thermal rocket with a planar ceramic heat exchanger mounted along the axis of the rocket is described. The heat exchanger was illuminated from the side by a millimeter-wave beam and fed propellant from above via a small tank containing high pressure argon or nitrogen. Short-range tests where the rocket was launched, tracked, and heated with the beam are described. The rockets were approximately 1.5 meters in length and 65 millimeters in diameter, with a liftoff mass of 1.8 kilograms. The rocket airframes were coated in aluminum and had a parachute recovery system activated via a timer and Pyrodex. At the rocket heat exchanger, the beam distance was 40 meters with a peak power intensity of 77 watts per square centimeter. and a total power of 32 kilowatts in a 30 centimeter diameter circle. An altitude of approximately 10 meters was achieved. Recommendations for improvements are discussed.

  9. Primer and short-range releaser pheromone properties of premolt female urine from the shore crab Carcinus maenas.

    Science.gov (United States)

    Ekerholm, Mattias; Hallberg, Eric

    2005-08-01

    The European shore crab Carcinus maenas is considered to rely on a female pheromone when mating. Evidence, however, is scarce on how the urine pheromone in itself affects males. We investigated male primer and releaser responses to female pheromones with methods that minimized effects from females, delivering female urine either as a pump-generated plume or deposited on a polyurethane sponge. We delivered the pheromone at different concentrations in far, near, and close/contact range to get a picture of how distance affects behavioral response. Our results show that substances in premolt female urine (PMU) function as primer and potent short-range releaser pheromones. Based on the olfactometer and sponge tests, we conclude that PMU stimulus in itself is sufficient to elicit increased search and mating-specific behaviors such as posing, posing search, cradle carrying, and stroking. Pheromone concentrations do not seem to be important for attenuating search and posing as long as the level is above a certain threshold concentration. Instead, pheromone levels seem to play a role in male acceptance of females, recruiting more males to respond, and generating better responses with increasing concentration.

  10. Short-range remote spectral sensor using mid-infrared semiconductor lasers with orthogonal code-division multiplexing approach

    Science.gov (United States)

    Morbi, Zulfikar; Ho, D. B.; Ren, H.-W.; Le, Han Q.; Pei, Shin Shem

    2002-09-01

    Demonstration of short-range multispectral remote sensing, using 3 to 4-micrometers mid- infrared Sb semiconductor lasers based on code-division multiplexing (CDM) architecture, is described. The system is built on a principle similar to intensity- modulated/direct-detection optical-CDMA for communications, but adapted for sensing with synchronous, orthogonal codes to distinguish different wavelength channels with zero interchannel correlation. The concept is scalable for any number of channels, and experiments with a two-wavelength system are conducted. The CDM-signal processing yielded a white-Gaussian-like system noise that is found to be near the theoretical level limited by the detector fundamental intrinsic noise. With sub-mW transmitter average power, the system was able to detect an open-air acetylene gas leak of 10-2 STP ft3/hr from 10-m away with time-varying, random, noncooperative backscatters. A similar experiment detected and positively distinguished hydrocarbon oil contaminants on water from bio-organic oils and detergents. Projection for more advanced systems suggests a multi-kilometer-range capability for watt-level transmitters, and hundreds of wavelength channels can also be accommodated for active hyperspectral remote sensing application.

  11. Will high-resolution global ocean models benefit coupled predictions on short-range to climate timescales?

    Science.gov (United States)

    Hewitt, Helene T.; Bell, Michael J.; Chassignet, Eric P.; Czaja, Arnaud; Ferreira, David; Griffies, Stephen M.; Hyder, Pat; McClean, Julie L.; New, Adrian L.; Roberts, Malcolm J.

    2017-12-01

    As the importance of the ocean in the weather and climate system is increasingly recognised, operational systems are now moving towards coupled prediction not only for seasonal to climate timescales but also for short-range forecasts. A three-way tension exists between the allocation of computing resources to refine model resolution, the expansion of model complexity/capability, and the increase of ensemble size. Here we review evidence for the benefits of increased ocean resolution in global coupled models, where the ocean component explicitly represents transient mesoscale eddies and narrow boundary currents. We consider lessons learned from forced ocean/sea-ice simulations; from studies concerning the SST resolution required to impact atmospheric simulations; and from coupled predictions. Impacts of the mesoscale ocean in western boundary current regions on the large-scale atmospheric state have been identified. Understanding of air-sea feedback in western boundary currents is modifying our view of the dynamics in these key regions. It remains unclear whether variability associated with open ocean mesoscale eddies is equally important to the large-scale atmospheric state. We include a discussion of what processes can presently be parameterised in coupled models with coarse resolution non-eddying ocean models, and where parameterizations may fall short. We discuss the benefits of resolution and identify gaps in the current literature that leave important questions unanswered.

  12. Short-ranged structural rearrangement and enhancement of mechanical properties of organosilicate glasses induced by ultraviolet radiation

    International Nuclear Information System (INIS)

    Iacopi, F.; Travaly, Y.; Eyckens, B.; Waldfried, C.; Abell, T.; Guyer, E.P.; Gage, D.M.; Dauskardt, R.H.; Sajavaara, T.; Houthoofd, K.; Grobet, P.; Jacobs, P.; Maex, K.

    2006-01-01

    The short-ranged bonding structure of organosilicate glasses can vary to a great extent and is directly linked to the mechanical properties of the thin film material. The combined action of ultraviolet (UV) radiation and thermal activation is shown to generate a pronounced rearrangement in the bonding structure of thin organosilicate glass films involving no significant compositional change or film densification. Nuclear magnetic resonance spectroscopy indicates loss of -OH groups and an increase of the degree of cross-linking of the organosilicate matrix for UV-treated films. Fourier transform infrared spectroscopy shows a pronounced enhancement of the Si-O-Si network bond structure, indicating the formation of more energetically stable silica bonds. Investigation with x-ray reflectivity and ellipsometric porosimetry indicated only minor film densification. As a consequence, the mechanical properties of microporous organosilicate dielectric films are substantially enhanced while preserving the organosilicate nature and pristine porosity of the films. UV-treated films show an increase in elastic modulus and hardness of more than 40%, and a similar improvement in fracture energy compared to untreated films. A minor increase in material dielectric constant from 3.0 to 3.15 was observed after UV treatment. This mechanism is of high relevance for the application of organosilicate glasses as dielectric materials for microelectronics interconnects, for which a high mechanical stability and a low dielectric constant are both essential film requirements

  13. Studies of wheel-running reinforcement: parameters of Herrnstein's (1970) response-strength equation vary with schedule order.

    Science.gov (United States)

    Belke, T W

    2000-05-01

    Six male Wistar rats were exposed to different orders of reinforcement schedules to investigate if estimates from Herrnstein's (1970) single-operant matching law equation would vary systematically with schedule order. Reinforcement schedules were arranged in orders of increasing and decreasing reinforcement rate. Subsequently, all rats were exposed to a single reinforcement schedule within a session to determine within-session changes in responding. For each condition, the operant was lever pressing and the reinforcing consequence was the opportunity to run for 15 s. Estimates of k and R(O) were higher when reinforcement schedules were arranged in order of increasing reinforcement rate. Within a session on a single reinforcement schedule, response rates increased between the beginning and the end of a session. A positive correlation between the difference in parameters between schedule orders and the difference in response rates within a session suggests that the within-session change in response rates may be related to the difference in the asymptotes. These results call into question the validity of parameter estimates from Herrnstein's (1970) equation when reinforcer efficacy changes within a session.

  14. Fractional order sliding-mode control based on parameters auto-tuning for velocity control of permanent magnet synchronous motor.

    Science.gov (United States)

    Zhang, BiTao; Pi, YouGuo; Luo, Ying

    2012-09-01

    A fractional order sliding mode control (FROSMC) scheme based on parameters auto-tuning for the velocity control of permanent magnet synchronous motor (PMSM) is proposed in this paper. The control law of the proposed F(R)OSMC scheme is designed according to Lyapunov stability theorem. Based on the property of transferring energy with adjustable type in F(R)OSMC, this paper analyzes the chattering phenomenon in classic sliding mode control (SMC) is attenuated with F(R)OSMC system. A fuzzy logic inference scheme (FLIS) is utilized to obtain the gain of switching control. Simulations and experiments demonstrate that the proposed FROSMC not only achieve better control performance with smaller chatting than that with integer order sliding mode control, but also is robust to external load disturbance and parameter variations. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

  15. Unstable Modes and Order Parameters of Bistable Signaling Pathways at Saddle-Node Bifurcations: A Theoretical Study Based on Synergetics

    Directory of Open Access Journals (Sweden)

    Till D. Frank

    2016-01-01

    Full Text Available Mathematical modeling has become an indispensable part of systems biology which is a discipline that has become increasingly popular in recent years. In this context, our understanding of bistable signaling pathways in terms of mathematical modeling is of particular importance because such bistable components perform crucial functions in living cells. Bistable signaling pathways can act as switches or memory functions and can determine cell fate. In the present study, properties of mathematical models of bistable signaling pathways are examined from the perspective of synergetics, a theory of self-organization and pattern formation founded by Hermann Haken. At the heart of synergetics is the concept of so-called unstable modes or order parameters that determine the behavior of systems as a whole close to bifurcation points. How to determine these order parameters for bistable signaling pathways at saddle-node bifurcation points is shown. The procedure is outlined in general and an explicit example is worked out in detail.

  16. Microsecond molecular dynamics simulation shows effect of slow loop dynamics on backbone amide order parameters of proteins

    DEFF Research Database (Denmark)

    Maragakis, Paul; Lindorff-Larsen, Kresten; Eastwood, Michael P

    2008-01-01

    . Molecular dynamics (MD) simulation provides a complementary approach to the study of protein dynamics on similar time scales. Comparisons between NMR spectroscopy and MD simulations can be used to interpret experimental results and to improve the quality of simulation-related force fields and integration......A molecular-level understanding of the function of a protein requires knowledge of both its structural and dynamic properties. NMR spectroscopy allows the measurement of generalized order parameters that provide an atomistic description of picosecond and nanosecond fluctuations in protein structure...... methods. However, apparent systematic discrepancies between order parameters extracted from simulations and experiments are common, particularly for elements of noncanonical secondary structure. In this paper, results from a 1.2 micros explicit solvent MD simulation of the protein ubiquitin are compared...

  17. Towards all-order Laurent expansion of generalized hypergeometric functions around rational values of parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kalmykov, M.Yu.; Kniehl, B.A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2008-07-15

    We prove the following theorems: 1) The Laurent expansions in {epsilon} of the Gauss hypergeometric functions {sub 2}F{sub 1}(I{sub 1}+a{epsilon},I{sub 2}+b{epsilon};I{sub 3}+(p)/(q)+c{epsilon};z), {sub 2}F{sub 1}(I{sub 1}+(p)/(q)+a{epsilon},I{sub 2}+(p/q)+b{epsilon};I{sub 3}+(p)/(q)+c{epsilon};z) and {sub 2}F{sub 1}(I{sub 1}+(p)/(q)+ a{epsilon},I{sub 2}+b{epsilon};I{sub 3}+(p)/(q)+c{epsilon};z), where I{sub 1},I{sub 2},I{sub 3},p,q are arbitrary integers, a,b,c are arbitrary numbers and {epsilon} is an infinitesimal parameter, are expressible in terms of multiple polylogarithms of q-roots of unity with coefficients that are ratios of polynomials; 2) The Laurent expansion of the Gauss hypergeometric function {sub 2}F{sub 1}(I{sub 1}+(p)/(q)+a{epsilon},I{sub 2}+b{epsilon};I{sub 3}+c{epsilon};z) is expressible in terms of multiple polylogarithms of q-roots of unity times powers of logarithm with coefficients that are ratios of polynomials; 3) The multiple inverse rational sums {sigma}{sup {infinity}}{sub j=1}({gamma}(j))/({gamma}(1+j-(p)/(q))) (z{sup j})/(j{sup c}) S{sub a{sub 1}}(j-1).. S{sub a{sub p}}(j-1) and the multiple rational sums {sigma}{sup {infinity}}{sub j=1} ({gamma}(j+(p)/(q)))/({gamma}(1+j)) (z{sup j})/(j{sup c}) S{sub a{sub 1}}(j-1).. S{sub a{sub p}}(j-1), where S{sub a}(j)={sigma}{sup j}{sub k=1}(1)/(k{sup a}) is a harmonic series and c is an arbitrary integer, are expressible in terms of multiple polylogarithms; 4) The generalized hypergeometric functions {sub p}F{sub p.1}((vector)A+(vector)a{epsilon};(vector)B+(vector)b{epsilon},(p)/(q)+B{sub p-1};z) and {sub p}F{sub p-1}((vector)A+(vector)a{epsilon},(p)/(q)+A{sub p};(vector)B+(vector)b{epsilon};z) are expressible in terms of multiple polylogarithms with coefficients that are ratios of polynomials. (orig.)

  18. Existence of positive solutions for nonlocal second-order boundary value problem with variable parameter in Banach spaces

    Directory of Open Access Journals (Sweden)

    Zhang Peiguo

    2011-01-01

    Full Text Available Abstract By obtaining intervals of the parameter λ, this article investigates the existence of a positive solution for a class of nonlinear boundary value problems of second-order differential equations with integral boundary conditions in abstract spaces. The arguments are based upon a specially constructed cone and the fixed point theory in cone for a strict set contraction operator. MSC: 34B15; 34B16.

  19. Clicking in shallow rivers: short-range echolocation of Irrawaddy and Ganges River dolphins in a shallow, acoustically complex habitat.

    Directory of Open Access Journals (Sweden)

    Frants H Jensen

    Full Text Available Toothed whales (Cetacea, odontoceti use biosonar to navigate their environment and to find and catch prey. All studied toothed whale species have evolved highly directional, high-amplitude ultrasonic clicks suited for long-range echolocation of prey in open water. Little is known about the biosonar signals of toothed whale species inhabiting freshwater habitats such as endangered river dolphins. To address the evolutionary pressures shaping the echolocation signal parameters of non-marine toothed whales, we investigated the biosonar source parameters of Ganges river dolphins (Platanista gangetica gangetica and Irrawaddy dolphins (Orcaella brevirostris within the river systems of the Sundarban mangrove forest. Both Ganges and Irrawaddy dolphins produced echolocation clicks with a high repetition rate and low source level compared to marine species. Irrawaddy dolphins, inhabiting coastal and riverine habitats, produced a mean source level of 195 dB (max 203 dB re 1 µPapp whereas Ganges river dolphins, living exclusively upriver, produced a mean source level of 184 dB (max 191 re 1 µPapp. These source levels are 1-2 orders of magnitude lower than those of similar sized marine delphinids and may reflect an adaptation to a shallow, acoustically complex freshwater habitat with high reverberation and acoustic clutter. The centroid frequency of Ganges river dolphin clicks are an octave lower than predicted from scaling, but with an estimated beamwidth comparable to that of porpoises. The unique bony maxillary crests found in the Platanista forehead may help achieve a higher directionality than expected using clicks nearly an octave lower than similar sized odontocetes.

  20. Order parameters and energies of analytic and singular vortex lines in rotating 3He-A

    International Nuclear Information System (INIS)

    Passvogel, T.; Schopohl, N.; Warnke, M.; Tewordt, L.

    1982-01-01

    We present the expressions of the generalized Ginzburg-Landau (GL) theory for the free energy and the supercurrent in terms of the d vector, the magnetic field H, and operators containing the spatial gradient and the rotation Ω. These expressions are then specialized to the Anderson--Brinkman--Morel (ABM) state. We consider eight single-vortex lines of cylindrical symmetry and radius R = [2mΩ/h]/sup -1/2/: the Mermin--Ho vortex, a second analytic vortex, and six singular vortices, i.e., the orbital and radial disgyrations, the orbital and radial phase vortices, and two axial phase vortices. These eight vortex states are determined by solving the Euler--Lagrange equations whose solutions minimize the GL free energy functional. For increasing field, the core radius of the I texture of the Mermin--Ho vortex tends to a limiting value, while the core radius of the d texture goes to zero. The gap of the singular vortices behaves like r/sup α/ for r→0, where α ranges between √1/2 and √9/2. The energy of the radial disgyration becomes lower than that of the Mermin--Ho vortex for fields H> or =6.5 H* = 6.5 x 25 G (at T = 0.99 T/sub c/ and for R = 10 L* = 60 μm, or Ω = 2.9 rad/sec). For R→2xi/sub T/ (xi/sub T/ is the GL coherence length) or Ω→Ω/sub c2/ (upper critical rotation speed), the energies of the singular vortices become lower than the energies of the analytic vortices. This is in agreement with the exact result of Schopohl for a vortex lattice at Ω/sub c/2 . Finally, we calculate the correction of order (1-T/T/sub c/) to the GL gap for the axial phase vortex

  1. Traplining in bumblebees (Bombus impatiens): a foraging strategy's ontogeny and the importance of spatial reference memory in short-range foraging.

    Science.gov (United States)

    Saleh, Nehal; Chittka, Lars

    2007-04-01

    To test the relative importance of long-term and working spatial memories in short-range foraging in bumblebees, we compared the performance of two groups of bees. One group foraged in a stable array of six flowers for 40 foraging bouts, thereby enabling it to establish a long-term memory of the array, and adjust its spatial movements accordingly. The other group was faced with an array that changed between (but not within) foraging bouts, and thus had only access to a working memory of the flowers that had been visited. Bees in the stable array started out sampling a variety of routes, but their tendency to visit flowers in a repeatable, stable order ("traplining") increased drastically with experience. These bees used shorter routes and converged on four popular paths. However, these routes were mainly formed through linking pairs of flowers by near-neighbour movements, rather than attempting to minimize overall travel distance. Individuals had variations to a primary sequence, where some bees used a major sequence most often, followed by a minor less used route, and others used two different routes with equal frequency. Even though bees foraging in the spatially randomized array had access to both spatial working memory and scent marks, this manipulation greatly disrupted foraging efficiency, mainly via an increase in revisitation to previously emptied flowers and substantially longer search times. Hence, a stable reference frame greatly improves foraging even for bees in relatively small arrays of flowers.

  2. Dynamical vanishing of the order parameter in a confined Bardeen-Cooper-Schrieffer Fermi gas after an interaction quench

    Science.gov (United States)

    Hannibal, S.; Kettmann, P.; Croitoru, M. D.; Axt, V. M.; Kuhn, T.

    2018-01-01

    We present a numerical study of the Higgs mode in an ultracold confined Fermi gas after an interaction quench and find a dynamical vanishing of the superfluid order parameter. Our calculations are done within a microscopic density-matrix approach in the Bogoliubov-de Gennes framework which takes the three-dimensional cigar-shaped confinement explicitly into account. In this framework, we study the amplitude mode of the order parameter after interaction quenches starting on the BCS side of the BEC-BCS crossover close to the transition and ending in the BCS regime. We demonstrate the emergence of a dynamically vanishing superfluid order parameter in the spatiotemporal dynamics in a three-dimensional trap. Further, we show that the signal averaged over the whole trap mirrors the spatiotemporal behavior and allows us to systematically study the effects of the system size and aspect ratio on the observed dynamics. Our analysis enables us to connect the confinement-induced modifications of the dynamics to the pairing properties of the system. Finally, we demonstrate that the signature of the Higgs mode is contained in the dynamical signal of the condensate fraction, which, therefore, might provide a new experimental access to the nonadiabatic regime of the Higgs mode.

  3. Strain and order-parameter coupling in Ni-Mn-Ga Heusler alloys from resonant ultrasound spectroscopy

    Science.gov (United States)

    Salazar Mejía, C.; Born, N.-O.; Schiemer, J. A.; Felser, C.; Carpenter, M. A.; Nicklas, M.

    2018-03-01

    Resonant ultrasound spectroscopy and magnetic susceptibility experiments have been used to characterize strain coupling phenomena associated with structural and magnetic properties of the shape-memory Heusler alloy series Ni50 +xMn25 -xGa25 (x =0 , 2.5, 5.0, and 7.5). All samples exhibit a martensitic transformation at temperature TM and ferromagnetic ordering at temperature TC, while the pure end member (x =0 ) also has a premartensitic transition at TP M, giving four different scenarios: TC>TP M>TM,TC>TM without premartensitic transition, TC≈TM , and TCorder parameters relating to magnetic ordering, a soft mode, and the electronic instability responsible for the large strains typical of martensitic transitions. Linear-quadratic or biquadratic coupling between these order parameters, either directly or indirectly via the common strains, is then used to explain the stabilities of the different structures. Acoustic losses are attributed to critical slowing down at the premartensite transition, to the mobility of interphases between coexisting phases at the martensitic transition, and to mobility of some aspect of the twin walls under applied stress down to the lowest temperatures at which measurements were made.

  4. Simulation study of signal formation in position sensitive planar p-on-n silicon detectors after short range charge injection

    International Nuclear Information System (INIS)

    Peltola, T.; Eremin, V.; Verbitskaya, E.; Härkönen, J.

    2017-01-01

    Segmented silicon detectors (micropixel and microstrip) are the main type of detectors used in the inner trackers of Large Hadron Collider (LHC) experiments at CERN. Due to the high luminosity and eventual high fluence of energetic particles, detectors with fast response to fit the short shaping time of 20–25 ns and sufficient radiation hardness are required. Charge collection measurements carried out at the Ioffe Institute have shown a reversal of the pulse polarity in the detector response to short-range charge injection. Since the measured negative signal is about 30–60% of the peak positive signal, the effect strongly reduces the CCE even in non-irradiated detectors. For further investigation of the phenomenon the measurements have been reproduced by TCAD simulations. As for the measurements, the simulation study was applied for the p-on-n strip detectors similar in geometry to those developed for the ATLAS experiment and for the Ioffe Institute designed p-on-n strip detectors with each strip having a window in the metallization covering the p + implant, allowing the generation of electron-hole pairs under the strip implant. Red laser scans across the strips and the interstrip gap with varying laser diameters and Si-SiO 2 interface charge densities ( Q f ) were carried out. The results verify the experimentally observed negative response along the scan in the interstrip gap. When the laser spot is positioned on the strip p + implant the negative response vanishes and the collected charge at the active strip increases respectively. The simulation results offer a further insight and understanding of the influence of the oxide charge density in the signal formation. The main result of the study is that a threshold value of Q f , that enables negligible losses of collected charges, is defined. The observed effects and details of the detector response for different charge injection positions are discussed in the context of Ramo's theorem.

  5. Simulation study of signal formation in position sensitive planar p-on-n silicon detectors after short range charge injection

    Science.gov (United States)

    Peltola, T.; Eremin, V.; Verbitskaya, E.; Härkönen, J.

    2017-09-01

    Segmented silicon detectors (micropixel and microstrip) are the main type of detectors used in the inner trackers of Large Hadron Collider (LHC) experiments at CERN. Due to the high luminosity and eventual high fluence of energetic particles, detectors with fast response to fit the short shaping time of 20-25 ns and sufficient radiation hardness are required. Charge collection measurements carried out at the Ioffe Institute have shown a reversal of the pulse polarity in the detector response to short-range charge injection. Since the measured negative signal is about 30-60% of the peak positive signal, the effect strongly reduces the CCE even in non-irradiated detectors. For further investigation of the phenomenon the measurements have been reproduced by TCAD simulations. As for the measurements, the simulation study was applied for the p-on-n strip detectors similar in geometry to those developed for the ATLAS experiment and for the Ioffe Institute designed p-on-n strip detectors with each strip having a window in the metallization covering the p+ implant, allowing the generation of electron-hole pairs under the strip implant. Red laser scans across the strips and the interstrip gap with varying laser diameters and Si-SiO2 interface charge densities (Qf) were carried out. The results verify the experimentally observed negative response along the scan in the interstrip gap. When the laser spot is positioned on the strip p+ implant the negative response vanishes and the collected charge at the active strip increases respectively. The simulation results offer a further insight and understanding of the influence of the oxide charge density in the signal formation. The main result of the study is that a threshold value of Qf, that enables negligible losses of collected charges, is defined. The observed effects and details of the detector response for different charge injection positions are discussed in the context of Ramo's theorem.

  6. Elastic strain relaxation in interfacial dislocation patterns: II. From long- and short-range interactions to local reactions

    Science.gov (United States)

    Vattré, A.

    2017-08-01

    The long- and short-range interactions as well as planar reactions between two infinitely periodic sets of crossing dislocations are investigated using anisotropic elasticity theory in face- (fcc) and body- (bcc) centered cubic materials. Two preliminary cases are proposed to examine the substantial changes in the elastic stress states and the corresponding strain energies due to a slight rearrangement in the internal dislocation geometries and characters. In general, significant differences and discrepancies resulting from the considered cubic crystal structure and the approximation of isotropic elasticity are exhibited. In a third scenario, special attention is paid to connecting specific internal dislocation structures from the previous cases with non-equilibrium configurations predicted by the quantized Frank-Bilby equation for the (111) fcc and (110) bcc twist grain boundaries. The present solutions lead to the formation of energetically favorable dislocation junctions with non-randomly strain-relaxed configurations of lower energy. In particular, the local dislocation interactions and reactions form equilibrium hexagonal-shaped patterns with planar three-fold dislocation nodes without producing spurious far-field stresses.Numerical application results are presented from a selection of cubic metals including aluminum, copper, tantalum, and niobium. In contrast to the fcc materials, asymmetric dislocation nodes occur in the anisotropic bcc cases, within which the minimum-energy paths for predicting the fully strain-relaxed dislocation patterns depend on the Zener anisotropic factor with respect to unity. The associated changes in the dislocation structures as well as the removal of the elastic strain energy upon relaxations are quantified and also discussed.

  7. Interplay of long-range and short-range Coulomb interactions in an Anderson-Mott insulator

    Science.gov (United States)

    Baćani, Mirko; Novak, Mario; Orbanić, Filip; Prša, Krunoslav; Kokanović, Ivan; Babić, Dinko

    2017-07-01

    In this paper, we tackle the complexity of coexisting disorder and Coulomb electron-electron interactions (CEEIs) in solids by addressing a strongly disordered system with intricate CEEIs and a screening that changes both with charge carrier doping level Q and temperature T . We report on an experimental comparative study of the T dependencies of the electrical conductivity σ and magnetic susceptibility χ of polyaniline pellets doped with dodecylbenzenesulfonic acid over a wide range. This material is special within the class of doped polyaniline by exhibiting in the electronic transport a crossover between a low-T variable range hopping (VRH) and a high-T nearest-neighbor hopping (NNH) well below room temperature. Moreover, there is evidence of a soft Coulomb gap ΔC in the disorder band, which implies the existence of a long-range CEEI. Simultaneously, there is an onsite CEEI manifested as a Hubbard gap U and originating in the electronic structure of doped polyaniline, which consists of localized electron states with dynamically varying occupancy. Therefore, our samples represent an Anderson-Mott insulator in which long-range and short-range CEEIs coexist. The main result of the study is the presence of a crossover between low- and high-T regimes not only in σ (T ) but also in χ (T ) , the crossover temperature T* being essentially the same for both observables over the entire doping range. The relatively large electron localization length along the polymer chains results in U being small, between 12 and 20 meV for the high and low Q , respectively. Therefore, the thermal energy at T* is sufficiently large to lead to an effective closing of the Hubbard gap and the consequent appearance of NNH in the electronic transport within the disorder band. ΔC is considerably larger than U , decreasing from 190 to 30 meV as Q increases, and plays the role of an activation energy in the NNH.

  8. Single-Chip Fully Integrated Direct-Modulation CMOS RF Transmitters for Short-Range Wireless Applications

    Directory of Open Access Journals (Sweden)

    M. Jamal Deen

    2013-08-01

    Full Text Available Ultra-low power radio frequency (RF transceivers used in short-range application such as wireless sensor networks (WSNs require efficient, reliable and fully integrated transmitter architectures with minimal building blocks. This paper presents the design, implementation and performance evaluation of single-chip, fully integrated 2.4 GHz and 433 MHz RF transmitters using direct-modulation power voltage-controlled oscillators (PVCOs in addition to a 2.0 GHz phase-locked loop (PLL based transmitter. All three RF transmitters have been fabricated in a standard mixed-signal CMOS 0.18 µm technology. Measurement results of the 2.4 GHz transmitter show an improvement in drain efficiency from 27% to 36%. The 2.4 GHz and 433 MHz transmitters deliver an output power of 8 dBm with a phase noise of −122 dBc/Hz at 1 MHz offset, while drawing 15.4 mA of current and an output power of 6.5 dBm with a phase noise of −120 dBc/Hz at 1 MHz offset, while drawing 20.8 mA of current from 1.5 V power supplies, respectively. The PLL transmitter delivers an output power of 9 mW with a locking range of 128 MHz and consumes 26 mA from 1.8 V power supply. The experimental results demonstrate that the RF transmitters can be efficiently used in low power WSN applications.

  9. Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

    International Nuclear Information System (INIS)

    Yu, Tang-Qing; Vanden-Eijnden, Eric; Chen, Pei-Yang; Chen, Ming; Samanta, Amit; Tuckerman, Mark

    2014-01-01

    The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency

  10. Order parameter free enhanced sampling of the vapor-liquid transition using the generalized replica exchange method.

    Science.gov (United States)

    Lu, Qing; Kim, Jaegil; Straub, John E

    2013-03-14

    The generalized Replica Exchange Method (gREM) is extended into the isobaric-isothermal ensemble, and applied to simulate a vapor-liquid phase transition in Lennard-Jones fluids. Merging an optimally designed generalized ensemble sampling with replica exchange, gREM is particularly well suited for the effective simulation of first-order phase transitions characterized by "backbending" in the statistical temperature. While the metastable and unstable states in the vicinity of the first-order phase transition are masked by the enthalpy gap in temperature replica exchange method simulations, they are transformed into stable states through the parameterized effective sampling weights in gREM simulations, and join vapor and liquid phases with a succession of unimodal enthalpy distributions. The enhanced sampling across metastable and unstable states is achieved without the need to identify a "good" order parameter for biased sampling. We performed gREM simulations at various pressures below and near the critical pressure to examine the change in behavior of the vapor-liquid phase transition at different pressures. We observed a crossover from the first-order phase transition at low pressure, characterized by the backbending in the statistical temperature and the "kink" in the Gibbs free energy, to a continuous second-order phase transition near the critical pressure. The controlling mechanisms of nucleation and continuous phase transition are evident and the coexistence properties and phase diagram are found in agreement with literature results.

  11. An extended Kalman filter approach to non-stationary Bayesian estimation of reduced-order vocal fold model parameters.

    Science.gov (United States)

    Hadwin, Paul J; Peterson, Sean D

    2017-04-01

    The Bayesian framework for parameter inference provides a basis from which subject-specific reduced-order vocal fold models can be generated. Previously, it has been shown that a particle filter technique is capable of producing estimates and associated credibility intervals of time-varying reduced-order vocal fold model parameters. However, the particle filter approach is difficult to implement and has a high computational cost, which can be barriers to clinical adoption. This work presents an alternative estimation strategy based upon Kalman filtering aimed at reducing the computational cost of subject-specific model development. The robustness of this approach to Gaussian and non-Gaussian noise is discussed. The extended Kalman filter (EKF) approach is found to perform very well in comparison with the particle filter technique at dramatically lower computational cost. Based upon the test cases explored, the EKF is comparable in terms of accuracy to the particle filter technique when greater than 6000 particles are employed; if less particles are employed, the EKF actually performs better. For comparable levels of accuracy, the solution time is reduced by 2 orders of magnitude when employing the EKF. By virtue of the approximations used in the EKF, however, the credibility intervals tend to be slightly underpredicted.

  12. Global exponential stability of neutral high-order stochastic Hopfield neural networks with Markovian jump parameters and mixed time delays.

    Science.gov (United States)

    Huang, Haiying; Du, Qiaosheng; Kang, Xibing

    2013-11-01

    In this paper, a class of neutral high-order stochastic Hopfield neural networks with Markovian jump parameters and mixed time delays is investigated. The jumping parameters are modeled as a continuous-time finite-state Markov chain. At first, the existence of equilibrium point for the addressed neural networks is studied. By utilizing the Lyapunov stability theory, stochastic analysis theory and linear matrix inequality (LMI) technique, new delay-dependent stability criteria are presented in terms of linear matrix inequalities to guarantee the neural networks to be globally exponentially stable in the mean square. Numerical simulations are carried out to illustrate the main results. © 2013 ISA. Published by ISA. All rights reserved.

  13. 2H(p, pp) n reaction as a probe of the short-range nuclear force

    International Nuclear Information System (INIS)

    Haftel, M.I.; Petersen, E.L.; Wallace, J.M.

    1976-01-01

    We examine the feasibility of using the 2 H(p, pp) n reaction as a means of extracting information about the short-range behavior of the nuclear force not obtainable from N-N scattering experiments. To do this we use several separable potentials and examine the predicted cross section in various regions of phase space and for beam energies between 14 and 65 MeV. The questions that we address are likely to be insensitive to Coulomb effects. Both the form factor and the energy dependence of the potentials have been modified from the usual Yamaguchi form. The form of the energy dependence is chosen to obtain phase-shift equivalence for two different form factors while guaranteeing a unitary two-body scattering amplitude. The sensitivity of breakup results to the on-shell and off-shell aspects of the nuclear force is examined and discussed. Significant on-shell sensitivity occurs for breakup amplitudes in all states and for cross sections over all regions of phase space. Off-shell sensitivity appears only in the S = 1/2, L = 0 breakup amplitudes, with all S = 3/2 and all L > 0 amplitudes exhibiting negligible off-shell dependence. This result leads to only a very small (< or = 5%) off-shell sensitivity for quasifree scattering. However, cross sections far from quasifree scattering, and in particular cross sections in the final-state interaction region of phase space, exhibit as much as a 50% variation for phase-shift-equivalent potentials. This sensitivity is small at low beam energy and increases with increasing energy. The energy dependence at negative energies of one potential is also altered to adjust the triton binding energy. This enables us to compare phase-shift-equivalent potentials differing off shell but predicting the same triton binding energy. The energy dependence of this potential is somewhat unconventional. Fixing of the triton binding energy reduces the off-shell sensitivity appreciably only for E approximately-less-than 20 MeV

  14. Stochastic Parameter Estimation of Non-Linear Systems Using Only Higher Order Spectra of the Measured Response

    Science.gov (United States)

    Vasta, M.; Roberts, J. B.

    1998-06-01

    Methods for using fourth order spectral quantities to estimate the unknown parameters in non-linear, randomly excited dynamic systems are developed. Attention is focused on the case where only the response is measurable and the excitation is unmeasurable and known only in terms of a stochastic process model. The approach is illustrated through application to a non-linear oscillator with both non-linear damping and stiffness and with excitation modelled as a stationary Gaussian white noise process. The methods have applications in studies of the response of structures to random environmental loads, such as wind and ocean wave forces.

  15. Calculation of Wakefields and Higher Order Modes for the New Design of the Vacuum Chamber of the ALICE Experiment for the HL-LHC

    CERN Document Server

    Wanzenberg, Rainer; CERN. Geneva. ATS Department

    2016-01-01

    The High Luminosity Large Hadron Collider (HL-LHC) project was started with the goal to extend the discovery potential of the Large Hadron Collider (LHC). The HL-LHC study implies also an upgraded dimensions of the ALICE beam pipe. The trapped monopole and dipole Higher Order Modes (HOMs) and the short range wakefields for the new design of the ALICE vacuum chamber were calculated with help of the computer codes MAFIA and ECHO2D. The results of the short range wakefields calculations and the HOMs calculations for the ALICE vacuum chamber with new dimensions are presented in this report. The short range wakefields are presented in terms of longitudinal and transverse wake potentials and also in terms of loss and kick parameters. The frequency, the loss parameter, the R/Q and the Qvalues and also power loss parameters are presented as result of the HOMs calculations and can be converted into impedance values.

  16. The role of the form factor and short-range correlation in the relativistic Hartree-Fock model for nuclear matter

    International Nuclear Information System (INIS)

    Hu, J.; Toki, H.; Wen, W.; Shen, H.

    2010-01-01

    The role of the form factor and short-range correlation in nuclear matter is studied within the relativistic Hartree-Fock approximation. We take, first, the mean-field approximation for meson fields and obtain the fluctuation terms of mesons to be used for the Fock energies. We introduce form factors in the meson-nucleon coupling vertices to take into account the finite-size effect of the nucleon. We use further the unitary correlation operator method for the treatment of the short-range correlation. The form factors of the size (Λ∝1.0 -2.0 GeV) of the nucleon-nucleon interaction cut down largely the contribution of the ρ-meson in the Fock term. The short-range correlation effect is not large but has a significant effect on the pion and ρ-meson energies in the relativistic Hartree-Fock approximation for nuclear matter. (orig.)

  17. The role of the form factor and short-range correlation in the relativistic Hartree-Fock model for nuclear matter

    Science.gov (United States)

    Hu, J.; Toki, H.; Wen, W.; Shen, H.

    2010-03-01

    The role of the form factor and short-range correlation in nuclear matter is studied within the relativistic Hartree-Fock approximation. We take, first, the mean-field approximation for meson fields and obtain the fluctuation terms of mesons to be used for the Fock energies. We introduce form factors in the meson-nucleon coupling vertices to take into account the finite-size effect of the nucleon. We use further the unitary correlation operator method for the treatment of the short-range correlation. The form factors of the size ( Λ ˜ 1.0 -2.0GeV) of the nucleon-nucleon interaction cut down largely the contribution of the ρ -meson in the Fock term. The short-range correlation effect is not large but has a significant effect on the pion and ρ -meson energies in the relativistic Hartree-Fock approximation for nuclear matter.

  18. High-field magnetization curve of random-anisotropy amorphous magnet: Observation of a crossover and link to structural short-range order

    Science.gov (United States)

    Filippi, J.; Amaral, V. S.; Barbara, B.

    1991-08-01

    High-field magnetization curves of the series of amorphous alloys DyxGd1-xNi have been measured up to 15 tesla and interpreted in the framework of the theory of Chudnovsky et al. The results show several features (high-field crossovers, correlation volume of local-anisotropy directions, ferromagnetic correlation length) all consistent with each other and in agreement with theoretical predictions.

  19. High-field magnetization curve of random-anisotropy amorphous magnet: Observation of a crossover and link to structural short-range order

    International Nuclear Information System (INIS)

    Filippi, J.; Amaral, V.S.; Barbara, B.

    1991-01-01

    High-field magnetization curves of the series of amorphous alloys Dy x Gd 1-x Ni have been measured up to 15 tesla and interpreted in the framework of the theory of Chudnovsky et al. The results show several features (high-field crossovers, correlation volume of local-anisotropy directions, ferromagnetic correlation length) all consistent with each other and in agreement with theoretical predictions

  20. Evidence of icosahedral short-range order in Zr70Cu30 and Zr70Cu29Pd1 metallic glasses

    DEFF Research Database (Denmark)

    Saksl, K.; Franz, H.; Jovari, P.

    2003-01-01

    Change in local atomic environment during crystallization of Zr-based glassy alloys was studied by extended x-ray absorption fine structure (EXAFS) spectroscopy. The formation of icosahedral quasicrystalline phase followed by crystallization of tetragonal CuZr2 has been observed in the Zr70Cu29Pd1...... glassy alloy during annealing up to 850 K. On the other hand, the binary Zr70Cu30 alloy shows a single glassy to crystalline CuZr2 phase transformation. The local atomic environment of as-quenched Zr70Cu30 alloy is matched to an icosahedral local atomic configuration, which is similar to that of the as......-quenched Zr70Cu29Pd1 alloy and the alloy annealed at 593 K containing icosahedral phase. Considering that the supercooled liquid region appears prior to crystallization in the Zr70Cu30 glassy alloy, the observed results support the theory claiming a strong correlation between the existence of local...

  1. Short-range order structures of self-assembled Ge quantum dots probed by multiple-scattering extended x-ray absorption fine structure

    International Nuclear Information System (INIS)

    Sun Zhihu; Wei Shiqiang; Kolobov, A.V.; Oyanagi, H.; Brunner, K.

    2005-01-01

    Multiple-scattering extended x-ray absorption fine structure (MS-EXAFS) has been used to investigate the local structures around Ge atoms in self-assembled Ge-Si quantum dots (QDs) grown on Si(001) substrate. The MS effect of Ge QDs is dominated by the scattering path Ge 0 →B 1 →B 2 →Ge 0 (DS2), which contributes a signal destructively interfering with that of the second shell single-scattering path (SS2). MS-EXAFS analysis reveals that the degree of Ge-Si intermixing for Ge-Si QDs strongly depends on the temperature at which the silicon cap layer is overgrown. It is found that the interatomic distances (R Ge-Ge and R Ge-Si ) within the third nearest-neighbor shells in Ge-Si QDs indicate the compressively strained nature of QDs. The present study demonstrates that the MS-EXAFS provides detailed information on the QDs strain and the Ge-Si mixing beyond the nearest neighbors

  2. Order parameters for symmetry-breaking structural transitions: The tetragonal-monoclinic transition in ZrO2

    Science.gov (United States)

    Thomas, John C.; Van der Ven, Anton

    2017-10-01

    Group/subgroup structural phase transitions are exploited in a wide variety of technologies, including those that rely on shape-memory behavior and on transformation toughening. Here, we introduce an approach to identify symmetry-adapted strain and shuffle order parameters for any group/subgroup structural transition between a high-symmetry parent phase and its symmetrically equivalent low-symmetry product phases. We show that symmetry-adapted atomic shuffle order parameters can be determined by the diagonalization of an orbital covariance matrix, formed by taking the covariance among the atomic displacement vectors of all symmetrically equivalent product phase variants. We use this approach to analyze the technologically important tetragonal to monoclinic structural phase transformation of ZrO2. We explore the energy landscapes, as calculated with density functional theory, along distinct paths that connect m ZrO2 to t ZrO2 and to other m ZrO2 variants. The calculations indicate favorable pairs of variants and reveal intermediate structures likely to exist at coherent twin boundaries and having relatively low deformation energy. We identify crystallographic features of the monoclinic ZrO2 variant that make it very sensitive to shape changing strains.

  3. Derivation and solution of a time-dependent, nonlinear, Schrodinger-like equation for the superconductivity order parameter

    International Nuclear Information System (INIS)

    Esrick, M.A.

    1981-01-01

    A time-dependent, nonlinear, Schrodinger-like equation for the superconductivity order parameter is derived from the Gor'kov equations. Three types of traveling wave solutions of the equation are discussed. The phases and amplitudes of these solutions propagate at different speeds. The first type of solution has an amplitude that propagates as a soliton and it is suggested that this solution might correspond to the recently observed propagating collective modes of the order parameter. The amplitude of the second type of solution propagates as a periodic disturbance in space and time. It is suggested that this type of solution might explain the recently observed multiple values of the superconductor energy gap as well as the spatially inhomogenous superconducting state. The third type of solution, which is of a more general character, might provide some insight into non-periodic, inhomogeneous states occuring in superconductors. It is also proposed that quasiparticle injection and microwave irradiation might generate soliton-like disturbances in superconductors

  4. Assessment of reduced-order unscented Kalman filter for parameter identification in 1-dimensional blood flow models using experimental data.

    Science.gov (United States)

    Caiazzo, A; Caforio, Federica; Montecinos, Gino; Muller, Lucas O; Blanco, Pablo J; Toro, Eluterio F

    2016-10-25

    This work presents a detailed investigation of a parameter estimation approach on the basis of the reduced-order unscented Kalman filter (ROUKF) in the context of 1-dimensional blood flow models. In particular, the main aims of this study are (1) to investigate the effects of using real measurements versus synthetic data for the estimation procedure (i.e., numerical results of the same in silico model, perturbed with noise) and (2) to identify potential difficulties and limitations of the approach in clinically realistic applications to assess the applicability of the filter to such setups. For these purposes, the present numerical study is based on a recently published in vitro model of the arterial network, for which experimental flow and pressure measurements are available at few selected locations. To mimic clinically relevant situations, we focus on the estimation of terminal resistances and arterial wall parameters related to vessel mechanics (Young's modulus and wall thickness) using few experimental observations (at most a single pressure or flow measurement per vessel). In all cases, we first perform a theoretical identifiability analysis on the basis of the generalized sensitivity function, comparing then the results owith the ROUKF, using either synthetic or experimental data, to results obtained using reference parameters and to available measurements. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Improved Hybrid Fireworks Algorithm-Based Parameter Optimization in High-Order Sliding Mode Control of Hypersonic Vehicles

    Directory of Open Access Journals (Sweden)

    Xiaomeng Yin

    2018-01-01

    Full Text Available With respect to the nonlinear hypersonic vehicle (HV dynamics, achieving a satisfactory tracking control performance under uncertainties is always a challenge. The high-order sliding mode control (HOSMC method with strong robustness has been applied to HVs. However, there are few methods for determining suitable HOSMC parameters for an efficacious control of HV, given that the uncertainties are randomly distributed. In this study, we introduce a hybrid fireworks algorithm- (FWA- based parameter optimization into HV control design to satisfy the design requirements with high probability. First, the complex relation between design parameters and the cost function that evaluates the likelihood of system instability and violation of design requirements is modeled via stochastic robustness analysis. Subsequently, we propose an efficient hybrid FWA to solve the complex optimization problem concerning the uncertainties. The efficiency of the proposed hybrid FWA-based optimization method is demonstrated in the search of the optimal HV controller, in which the proposed method exhibits a better performance when compared with other algorithms.

  6. Assessment of aerosol radiation environment in short-range region of ChNPP during building of the new safe confinment

    International Nuclear Information System (INIS)

    Garger, E.K.; Shynkarenko, V.K.; Kashpur, V.A.; Skoryak, G.G.; Kalinovsky, A.K.

    2017-01-01

    Variability of 137 Cs volume activity in a subsurface layer of the atmosphere of a short-range region of the object ''Shelter'' (object ''Ukryttya'') during the works on building of a new safety confinement in 2016 was investigated. Influence of the type and location of works, weather conditions, and sampling points was shown. Excess of medial permissible concentrations of 137 Cs in the air was not fixed during the observations. However, due to the averaging of the measured values of the volume activity for the exposure time of the filter and use of the stationary aerosol samplers, it cannot ensure the absence of excess of the permissible concentrations at the locations of works and on the propagation path of the local emission plumes. In 2016, as well as in 2013 - 2015, high levels of 137 Cs volume activity in the air were preferentially localized near to the machine hall of the 4th block and near to the places of ground works at the industrial site [ 1]. Concurrently the levels of volume activity essentially grew (practically by the order of magnitude) due to the intense works on the machine hall transformation. The conservative estimation of volume activity of isotopes of the plutonium, executed in the assumption of fuel composition of hot particles, showed the presence of substantial excess of permissible limits even for the average values within, at least, four weeks. Absence of reliable correlation (R = -0.09) of 137 Cs volume activity in the air near to the machine hall and near to the aerosol sampler 1,4 km remote from it testifies the localization of pollution within the industrial site.

  7. Local order and concentration fluctuations in K-Pb and Rb-Pb alloys

    International Nuclear Information System (INIS)

    Akinlade, O.

    1992-08-01

    The concentration fluctuations in the long wavelength limit S cc (0), short range order parameter and free energy of mixing of K-Pb and Rb-Pb alloys have been studied within the framework of the quasi-chemical theory. It is observed that the simple model could be used to shed more insight into the nature of chemical ordering that exists in such strongly compound forming binary alloys. (author). 19 refs, 6 figs, 1 tab

  8. Short-range forecast of Shershnevskoie (South Ural) water-storage algal blooms: preliminary results of predictors' choosing and membership functions' construction

    Science.gov (United States)

    Gayazova, Anna; Abdullaev, Sanjar

    2014-05-01

    Short-range forecasting of algal blooms in drinking water reservoirs and other waterbodies is an actual element of water treatment system. Particularly, Shershnevskoie reservoir - the source of drinking water for Chelyabinsk city (South Ural region of Russia) - is exposed to interannual, seasonal and short-range fluctuations of blue-green alga Aphanizomenon flos-aquae and other dominant species abundance, which lead to technological problems and economic costs and adversely affect the water treatment quality. Whereas the composition, intensity and the period of blooms affected not only by meteorological seasonal conditions but also by ecological specificity of waterbody, that's important to develop object-oriented forecasting, particularly, search for an optimal number of predictors for such forecasting. Thereby, firstly fuzzy logic and fuzzy artificial neural network patterns for blue-green alga Microcystis aeruginosa (M. aeruginosa) blooms prediction in nearby undrained Smolino lake were developed. These results subsequently served as the base to derive membership functions for Shernevskoie reservoir forecasting patterns. Time series with the total lenght about 138-159 days of dominant species seasonal abundance, water temperature, cloud cover, wind speed, mineralization, phosphate and nitrate concentrations were obtained through field observations held at Lake Smolino (Chelyabinsk) in the warm season of 2009 and 2011 with time resolution of 2-7 days. The cross-correlation analysis of the data revealed the potential predictors of M. aeruginosa abundance quasi-periodic oscillations: green alga Pediastrum duplex (P. duplex) abundance and mineralization for 2009, P. duplex abundance, water temperature and concentration of nitrates for 2011. According to the results of cross-correlation analysis one membership function "P. duplex abundance" and one rule linking M. aeruginosa and P. duplex abundances were set up for database of 2009. Analogically, for database of 2011

  9. Structure Factor of a Hard-core Fluid with Short-range Yukawa Attraction: Analytical FMSA Theory against Monte Carlo Simulations.

    Czech Academy of Sciences Publication Activity Database

    Melnyk, R.; Nezbeda, Ivo; Trokhymchuk, A.

    2016-01-01

    Roč. 114, 16-17 (2016), s. 2523-2529 ISSN 0026-8976 Institutional support: RVO:67985858 Keywords : hard-core fluid * reference system * short-range Yukawa attraction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.870, year: 2016

  10. The order parameter of glass transition: Spontaneously delocalized nanoscale solitary wave with transverse ripplon-like soft wave

    Directory of Open Access Journals (Sweden)

    Jia Lin Wu

    2013-06-01

    Full Text Available In macromolecular self-avoiding random walk, movement of each chain-particle accompanies an instantaneous spin system with de Gennes n = 0 that provides extra energy, extra vacancy volume and relaxation time needed for chain-particles co-movement. Using these additional and instantaneous spin systems not only directly yields the same Brownian motion mode in glass transition (GT and reptation-tube model, but also proves that the entangled chain length corresponding to the Reynolds number in hydrodynamics and the inherent diffusion - delocalization mode of entangled chains, from frozen glass state to melt liquid state, is a chain-size solitary wave with transverse ripplon-like soft wave. Thus, the order parameter of GT is found. The various currently available GT theories, such as Static Replica, Random First-Order Transition, Potential Energy Landscape, Mode-Coupling and Nanoscale Heterogeneity, can be unified using the additional and instantaneous spin system. GT served as an inspiration and continues to serve as the paradigm in the universal random delocalization transitions from disorder to more disorder until turbulence.

  11. An increase of structural order parameter in Fe endash Co endash V soft magnetic alloy after thermal aging

    International Nuclear Information System (INIS)

    Zhu, Q.; Li, L.; Masteller, M.S.; Del Corso, G.J.

    1996-01-01

    Alloys of Fe 49 Co 49 V 2 (Hiperco Alloy 50) (Hiperco is a registered trademark of CRS Holdings, Inc.), both annealed and thermally aged, were studied using anomalous synchrotron x-ray and neutron powder diffraction. Rietveld and diffraction profile analysis indicated both an increase in the structural order parameter and a small lattice expansion (∼0.0004 A) after aging at 450 degree C for 200 h. In addition, a cubic minority phase (<0.3%) was identified in the open-quote open-quote annealed close-quote close-quote sample, which increased noticeably (0.3%→0.8%) as a result of aging. The presence of antiphase domain boundaries in the alloys was also revealed. These results directly correlate with the observed changes in the magnetization behavior and challenge the notion that a open-quote open-quote fully close-quote close-quote ordered Fe endash Co alloy demonstrates optimum soft magnetic properties. copyright 1996 American Institute of Physics

  12. Onset of local ordering in some copper-based alloys: critical solute concentration vis-a-vis various solutionhardening parameters

    Science.gov (United States)

    Butt, Muhammad Zakria; Noshi, Mozina; Bashir, Farooq

    2008-12-01

    The mode of planar distribution of solute atoms in Cu single crystals alloyed with 0.5 to 8.0 at.%Ge has been investigated via the temperature dependence of the critical resolved shear stress of these alloys. It is found that there exists a critical solute concentration c m ≈ 5 at.%Ge below which the distribution of solute atoms in the crystal is random, and above which some local ordering occurs. This together with such data available in the literature for Cu-Zn, Cu-Al and Cu-Mn alloys, i.e. c m ≈7 at. %Zn, 7 at.%Al and 1 at.%Mn, when examined as a function of the size-misfit factor δ = (1/ b)(d b/d c)of a given binary alloy system, shows that the value of c m strongly depends on δ; the smaller the magnitude of δ, the greater the value of c m and vice versa. Also, the value of c m is found to correlate well with the electron-to-atom ratio ( e/a)of the Cu-Zn, Cu-Al, Cu-Ge and Cu-Mn alloys with the solute concentration c = c m . However, no systematic correlation exists between the critical solute concentration c m for the onset of local ordering and the modulus-mismatch parameter η = (1/ G)(d G/d c).

  13. How Confinement-Induced Structures Alter the Contribution of Hydrodynamic and Short-Ranged Repulsion Forces to the Viscosity of Colloidal Suspensions

    Directory of Open Access Journals (Sweden)

    Meera Ramaswamy

    2017-10-01

    Full Text Available Confined systems ranging from the atomic to the granular are ubiquitous in nature. Experiments and simulations of such atomic and granular systems have shown a complex relationship between the microstructural arrangements under confinement, the short-ranged particle stresses, and flow fields. Understanding the same correlation between structure and rheology in the colloidal regime is important due to the significance of such suspensions in industrial applications. Moreover, colloidal suspensions exhibit a wide range of structures under confinement that could considerably modify such force balances and the resulting viscosity. Here, we use a combination of experiments and simulations to elucidate how confinement-induced structures alter the relative contributions of hydrodynamic and short-range repulsive forces to produce up to a tenfold change in the viscosity. In the experiments we use a custom-built confocal rheoscope to image the particle configurations of a colloidal suspension while simultaneously measuring its stress response. We find that as the gap decreases below 15 particle diameters, the viscosity first decreases from its bulk value, shows fluctuations with the gap, and then sharply increases for gaps below 3 particle diameters. These trends in the viscosity are shown to strongly correlate with the suspension microstructure. Further, we compare our experimental results to those from two different simulations techniques, which enables us to determine the relative contributions of hydrodynamic and short-range repulsive stresses to the suspension rheology. The first method uses the lubrication approximation to find the hydrodynamic stress and includes a short-range repulsive force between the particles while the second is a Stokesian dynamics simulation that calculates the full hydrodynamic stress in the suspension. We find that the decrease in the viscosity at moderate confinements has a significant contribution from both the

  14. Unusual mechanism for the short-range electron transfer within gold-alkanethiol-ionic-liquid films of subnanometer thickness

    International Nuclear Information System (INIS)

    Khoshtariya, Dimitri E.; Dolidze, Tina D.; Eldik, Rudi van

    2009-01-01

    Exploiting nanoscopically tunable composite gold-alkanethiol-ionic-liquid/ferrocene self-assembled systems with tunable electron transfer distance, we discovered in the case of thinner alkanethiol films a thermally activated electron transfer pattern totally controlled by the viscosity-related slow relaxation mode(s) of the ionic liquid acting as the reactant's fluctuating environment. This pattern manifested through the activation enthalpy and volume parameters that are identical to those for viscous flow was explained in terms of the extreme adiabatic mechanism with a vanishing Marcus barrier (via the exponential Franck-Condon-like term approaching unity).

  15. Chiral effective field theory for nuclear matter including long- and short-range multi-nucleon interactions

    Directory of Open Access Journals (Sweden)

    Oller J.A.

    2010-04-01

    Full Text Available We review on a novel chiral power counting scheme for in-medium chiral perturbation theory with nucleons and pions as degrees of freedom. It allows for a systematic expansion taking into account local as well as pion-mediated inter-nucleon interactions. Based on this power counting, one can identify classes of nonperturbative diagrams that require a resummation. As a method for performing those resummations we review on the techniques of Unitary Chiral Pertubation Theory for nucleon-nucleon interactions. We then apply both power counting and non-perturbative methods to the example of calculating the pion self-energy in asymmetric nuclear matter up-to-and-including next-to-leading order. It is shown that the leading corrections involving in-medium nucleon-nucleon interactions cancel between each other at given chiral orders.

  16. Short-Range Correlated Magnetic Core-Shell CrO2/Cr2O3 Nanorods: Experimental Observations and Theoretical Considerations

    Directory of Open Access Journals (Sweden)

    Ashish C. Gandhi

    2018-05-01

    Full Text Available With the evolution of synthesis and the critical characterization of core-shell nanostructures, short-range magnetic correlation is of prime interest in employing their properties to develop novel devices and widespread applications. In this regard, a novel approach of the magnetic core-shell saturated magnetization (CSSM cylinder model solely based on the contribution of saturated magnetization in one-dimensional CrO2/Cr2O3 core-shell nanorods (NRs has been developed and applied for the determination of core-diameter and shell-thickness. The nanosized effect leads to a short-range magnetic correlation of ferromagnetic core-CrO2 extracted from CSSM, which can be explained using finite size scaling method. The outcome of this study is important in terms of utilizing magnetic properties for the critical characterization of core-shell nanomagnetic materials.

  17. Direct-Bandgap InAs Quantum-Dots Have Long-Range Electron--Hole Exchange Whereas Indirect Gap Si Dots Have Short-Range Exchange

    International Nuclear Information System (INIS)

    Juo, J.W.; Franceschetti, A.; Zunger, A.

    2009-01-01

    Excitons in quantum dots manifest a lower-energy spin-forbidden 'dark' state below a spin-allowed 'bright' state; this splitting originates from electron-hole (e-h) exchange interactions, which are strongly enhanced by quantum confinement. The e-h exchange interaction may have both a short-range and a long-range component. Calculating numerically the e-h exchange energies from atomistic pseudopotential wave functions, we show here that in direct-gap quantum dots (such as InAs) the e-h exchange interaction is dominated by the long-range component, whereas in indirect-gap quantum dots (such as Si) only the short-range component survives. As a result, the exciton dark/bright splitting scales as 1/R 2 in InAs dots and 1/R 3 in Si dots, where R is the quantum-dot radius.

  18. A simplified fixed-point perturbation theory and its application to the coulomb + short-range potential

    International Nuclear Information System (INIS)

    Znojil, M.

    1986-01-01

    The radial Schroedinger equation and its bound-state solutions for the interaction V(r)=Vsub(coulomb)+Vsub(Pade), where Vsub(Pade)(r)=(b+cr)/(1+drsup(2)) are considered. In order to construct exactly the Feshbach effective Hamiltonian Hsup(eff), the fixed-point-substraction technique is employed and its simplification is proposed. The first two terms in the resulting asymptotic expansions of PSIsub(n) and Hsup(eff) are calculated and interpreted as a new type of perturbation theory

  19. Three-dimensional short-range MR angiography and multiplanar reconstruction images in the evaluation of neurovascular compression in hemifacial spasm

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Woo Suk; Kim, Eui Jong; Lee, Jae Gue; Rhee, Bong Arm [Kyunghee Univ. Hospital, Seoul (Korea, Republic of)

    1998-08-01

    To evaluate the diagnostic efficacy of three-dimensional(3D) short-range MR angiography(MRA) and multiplanar reconstruction(MPR) imaging in hemifacial spasm(HS). Materials and Methods : Two hundreds patients with HS were studied using a 1.5T MRI system with a 3D time-of-flight(TOF) MRA sequence. To reconstruct short-range MRA, 6-10 source images near the 7-8th cranial nerve complex were processed using a maximum-intensity projection technique. In addition, an MPR technique was used to investigate neurovascular compression. We observed the relationship between the root-exit zone(REZ) of the 7th cranial nerve and compressive vessel, and identified the compressive vessels on symptomatic sides. To investigate neurovascular contact, asymptomatic contralateral sides were also evaluated. Results : MRI showed that in 197 of 200 patients there was vascular compression or contact with the facial nerve REZ on symptomatic sides. One of the three remaining patients was suffering from acoustic neurinoma on the symptomatic side, while in two patients there were no definite abnormal findings.Compressive vessels were demonstrated in all 197 patients; 80 cases involved the anterior inferior cerebellar artery(AICA), 74 the posterior cerebellar artery(PICA), 13 the vertebral artery(VA), 16 the VA and AICA, eight the VA and PICA, and six the AICA and PICA. In all 197 patients, compressive vessels were reconstructed on one 3D short-range MRA image without discontinuation from vertebral or basilar arteries. 3D MPR studies provided additional information such as the direction of compression and course of the compressive vessel. In 31 patients there was neurovascular contact on the contralateral side at the 7-8th cranial nerve complex. Conclusion : Inpatients with HS, 3D short-range MRA and MPR images are excellent and very helpful for the investigation of neurovascular compression and the identification of compressive vessels.

  20. Altered Long- and Short-Range Functional Connectivity in Patients with Betel Quid Dependence: A Resting-State Functional MRI Study

    Directory of Open Access Journals (Sweden)

    Tao Liu

    2016-12-01

    Full Text Available Objective: Addiction is a chronic relapsing brain disease. Brain structural abnormalities may constitute an abnormal neural network that underlies the risk of drug dependence. We hypothesized that individuals with Betel Quid Dependence (BQD have functional connectivity alterations that can be described by long- and short-range functional connectivity density(FCD maps. Methods: We tested this hypothesis using functional magnetic resonance imaging (fMRI data from subjects of the Han ethnic group in Hainan, China. Here, we examined BQD individuals (n = 33 and age-, sex-, and education-matched healthy controls (HCs (n = 32 in a rs-fMRI study to observe FCD alterations associated with the severity of BQD. Results: Compared with HCs, long-range FCD was decreased in the right anterior cingulate cortex (ACC and increased in the left cerebellum posterior lobe (CPL and bilateral inferior parietal lobule (IPL in the BQD group. Short-range FCD was reduced in the right ACC and left dorsolateral prefrontal cortex (dlPFC, and increased in the left CPL. The short-range FCD alteration in the right ACC displayed a negative correlation with the Betel Quid Dependence Scale (BQDS (r=-0.432, P=0.012, and the long-range FCD alteration of left IPL showed a positive correlation with the duration of BQD(r=0.519, P=0.002 in BQD individuals. Conclusions: fMRI revealed differences in long- and short- range FCD in BQD individuals, and these alterations might be due to BQ chewing, BQ dependency, or risk factors for developing BQD.

  1. Three-dimensional short-range MR angiography and multiplanar reconstruction images in the evaluation of neurovascular compression in hemifacial spasm

    International Nuclear Information System (INIS)

    Choi, Woo Suk; Kim, Eui Jong; Lee, Jae Gue; Rhee, Bong Arm

    1998-01-01

    To evaluate the diagnostic efficacy of three-dimensional(3D) short-range MR angiography(MRA) and multiplanar reconstruction(MPR) imaging in hemifacial spasm(HS). Materials and Methods : Two hundreds patients with HS were studied using a 1.5T MRI system with a 3D time-of-flight(TOF) MRA sequence. To reconstruct short-range MRA, 6-10 source images near the 7-8th cranial nerve complex were processed using a maximum-intensity projection technique. In addition, an MPR technique was used to investigate neurovascular compression. We observed the relationship between the root-exit zone(REZ) of the 7th cranial nerve and compressive vessel, and identified the compressive vessels on symptomatic sides. To investigate neurovascular contact, asymptomatic contralateral sides were also evaluated. Results : MRI showed that in 197 of 200 patients there was vascular compression or contact with the facial nerve REZ on symptomatic sides. One of the three remaining patients was suffering from acoustic neurinoma on the symptomatic side, while in two patients there were no definite abnormal findings.Compressive vessels were demonstrated in all 197 patients; 80 cases involved the anterior inferior cerebellar artery(AICA), 74 the posterior cerebellar artery(PICA), 13 the vertebral artery(VA), 16 the VA and AICA, eight the VA and PICA, and six the AICA and PICA. In all 197 patients, compressive vessels were reconstructed on one 3D short-range MRA image without discontinuation from vertebral or basilar arteries. 3D MPR studies provided additional information such as the direction of compression and course of the compressive vessel. In 31 patients there was neurovascular contact on the contralateral side at the 7-8th cranial nerve complex. Conclusion : Inpatients with HS, 3D short-range MRA and MPR images are excellent and very helpful for the investigation of neurovascular compression and the identification of compressive vessels

  2. Topological and Graph-Coloring Conditions on the Parameter-Independent Stability of Second-Order Networked Systems

    NARCIS (Netherlands)

    Koerts, Filip; Bürger, Mathias; van der Schaft, Abraham; De Persis, Claudio

    2017-01-01

    In this paper, we study parameter-independent stability in qualitatively heterogeneous passive networked systems containing damped and undamped nodes. Given the graph topology and a set of damped nodes, we ask if output consensus is achieved for all system parameter values. For given parameter

  3. On-line adaptive battery impedance parameter and state estimation considering physical principles in reduced order equivalent circuit battery models part 2. Parameter and state estimation

    Science.gov (United States)

    Fleischer, Christian; Waag, Wladislaw; Heyn, Hans-Martin; Sauer, Dirk Uwe

    2014-09-01

    Lithium-ion battery systems employed in high power demanding systems such as electric vehicles require a sophisticated monitoring system to ensure safe and reliable operation. Three major states of the battery are of special interest and need to be constantly monitored. These include: battery state of charge (SoC), battery state of health (capacity fade determination, SoH), and state of function (power fade determination, SoF). The second paper concludes the series by presenting a multi-stage online parameter identification technique based on a weighted recursive least quadratic squares parameter estimator to determine the parameters of the proposed battery model from the first paper during operation. A novel mutation based algorithm is developed to determine the nonlinear current dependency of the charge-transfer resistance. The influence of diffusion is determined by an on-line identification technique and verified on several batteries at different operation conditions. This method guarantees a short response time and, together with its fully recursive structure, assures a long-term stable monitoring of the battery parameters. The relative dynamic voltage prediction error of the algorithm is reduced to 2%. The changes of parameters are used to determine the states of the battery. The algorithm is real-time capable and can be implemented on embedded systems.

  4. Extracting rephase-invariant CP and CPT violating parameters from asymmetries of time-ordered integrated rates of correlated decays of entangled mesons

    International Nuclear Information System (INIS)

    Huang, Zhijie; Shi, Yu.

    2012-01-01

    We present a general model-independent formalism of measuring CP and CPT violating parameters through time-ordered integrated rates of correlated decays of C=±1 entangled states of neutral pseudoscalar mesons. We give the general formulae of CP and CPT violating parameters in terms of four measurable asymmetries defined for the time-ordered integrated rates, applicable to all kinds of decay product. Two special cases which are often realized in experiments are discussed specifically. (orig.)

  5. Analysis of the Impact of Storage Parameters and the Size of Orders on the Choice of the Method for Routing Order Picking

    Directory of Open Access Journals (Sweden)

    Grzegorz Tarczyński

    2012-01-01

    Full Text Available The paper presents an analysis of the impact of the number of picking aisles, slots in a rack, the size of pick lists, and the routing method on the performance of the order picking process. In the analysis, the forklift truck's maneuvers such as turns back and turns aside, omitted by some scientists, are considered. Although only random storage assignment is examined in this paper, the possible congestion effect is considered. Experiments were performed by the use of simulations. (original abstract

  6. Comparison of short-range rapidity correlations in anti pp and pp interactions at √S = 53 GeV

    International Nuclear Information System (INIS)

    Breakstone, A.; Crawley, H.B.; Firestone, A.; Gorbics, M.; Lamsa, J.W.; Meyer, W.T.

    1982-01-01

    Measurements are presented of two-particle rapidity correlations in anti pp and pp at √S = 53 GeV. The data were recorded at the CERN-ISR using the Split Field Magnet spectrometer with a minimum bias trigger. Short range correlations in normal inelastic events with measured charged multiplicities nsub(ch) >= 4 are observed for pairs of charged particles in all charge combinations. Within the experimental errors no differences are observed between the analogous correlations in pp and anti pp interactions. (orig.)

  7. Intentionally Short Range Communications (ISRC)

    Science.gov (United States)

    1993-05-01

    molecular oxygen in the atmosphere at 60 GHz (figure 9 LIppolito, 1981]). The MMW range is similar to that of the UV links. 3.3.1 Variable Range Similar to...option also requires that the signal be strong enough to overcome the noise from the solar and background sources, although the molecular oxygen and... emisions . Lasing will occur only within the cavity when the alignment is correct and not lasing othem ise. Such a cavity is dcteclable only when an observer

  8. First-order exchange coefficient coupling for simulating surface water-groundwater interactions: Parameter sensitivity and consistency with a physics-based approach

    Science.gov (United States)

    Ebel, B.A.; Mirus, B.B.; Heppner, C.S.; VanderKwaak, J.E.; Loague, K.

    2009-01-01

    Distributed hydrologic models capable of simulating fully-coupled surface water and groundwater flow are increasingly used to examine problems in the hydrologic sciences. Several techniques are currently available to couple the surface and subsurface; the two most frequently employed approaches are first-order exchange coefficients (a.k.a., the surface conductance method) and enforced continuity of pressure and flux at the surface-subsurface boundary condition. The effort reported here examines the parameter sensitivity of simulated hydrologic response for the first-order exchange coefficients at a well-characterized field site using the fully coupled Integrated Hydrology Model (InHM). This investigation demonstrates that the first-order exchange coefficients can be selected such that the simulated hydrologic response is insensitive to the parameter choice, while simulation time is considerably reduced. Alternatively, the ability to choose a first-order exchange coefficient that intentionally decouples the surface and subsurface facilitates concept-development simulations to examine real-world situations where the surface-subsurface exchange is impaired. While the parameters comprising the first-order exchange coefficient cannot be directly estimated or measured, the insensitivity of the simulated flow system to these parameters (when chosen appropriately) combined with the ability to mimic actual physical processes suggests that the first-order exchange coefficient approach can be consistent with a physics-based framework. Copyright ?? 2009 John Wiley & Sons, Ltd.

  9. Long-range versus short-range correlations in the two-neutron transfer reaction 64Ni(18O,16O)66Ni

    Science.gov (United States)

    Paes, B.; Santagati, G.; Vsevolodovna, R. Magana; Cappuzzello, F.; Carbone, D.; Cardozo, E. N.; Cavallaro, M.; García-Tecocoatzi, H.; Gargano, A.; Ferreira, J. L.; Lenzi, S. M.; Linares, R.; Santopinto, E.; Vitturi, A.; Lubian, J.

    2017-10-01

    Recently, various two-neutron transfer studies using the (18O,16O) reaction were performed with a large success. This was achieved because of a combined use of the microscopic quantum description of the reaction mechanism and of the nuclear structure. In the present work we use this methodology to study the two-neutron transfer reaction of the 18O+64Ni system at 84 MeV incident energy, to the ground and first 2+ excited state of the residual 66Ni nucleus. All the experimental data were measured by the large acceptance MAGNEX spectrometer at the Instituto Nazionale di Fisica Nucleare -Laboratori Nazionali del Sud (Italy). We have performed exact finite range cross section calculations using the coupled channel Born approximation (CCBA) and coupled reaction channel (CRC) method for the sequential and direct two-neutron transfers, respectively. Moreover, this is the first time that the formalism of the microscopic interaction boson model (IBM-2) was applied to a two-neutron transfer reaction. From our results we conclude that for two-neutron transfer to the ground state of 66Ni, the direct transfer is the dominant reaction mechanism, whereas for the transfer to the first excited state of 66Ni, the sequential process dominates. A competition between long-range and short-range correlations is discussed, in particular, how the use of two different models (Shell model and IBM's) help to disentangle long- and short-range correlations.

  10. Statistical Short-Range Guidance for Peak Wind Speed Forecasts on Kennedy Space Center/Cape Canaveral Air Force Station: Phase I Results

    Science.gov (United States)

    Lambert, Winifred C.; Merceret, Francis J. (Technical Monitor)

    2002-01-01

    This report describes the results of the ANU's (Applied Meteorology Unit) Short-Range Statistical Forecasting task for peak winds. The peak wind speeds are an important forecast element for the Space Shuttle and Expendable Launch Vehicle programs. The Keith Weather Squadron and the Spaceflight Meteorology Group indicate that peak winds are challenging to forecast. The Applied Meteorology Unit was tasked to develop tools that aid in short-range forecasts of peak winds at tower sites of operational interest. A 7 year record of wind tower data was used in the analysis. Hourly and directional climatologies by tower and month were developed to determine the seasonal behavior of the average and peak winds. In all climatologies, the average and peak wind speeds were highly variable in time. This indicated that the development of a peak wind forecasting tool would be difficult. Probability density functions (PDF) of peak wind speed were calculated to determine the distribution of peak speed with average speed. These provide forecasters with a means of determining the probability of meeting or exceeding a certain peak wind given an observed or forecast average speed. The climatologies and PDFs provide tools with which to make peak wind forecasts that are critical to safe operations.

  11. Scalable improvement of SPME multipolar electrostatics in anisotropic polarizable molecular mechanics using a general short-range penetration correction up to quadrupoles.

    Science.gov (United States)

    Narth, Christophe; Lagardère, Louis; Polack, Étienne; Gresh, Nohad; Wang, Qiantao; Bell, David R; Rackers, Joshua A; Ponder, Jay W; Ren, Pengyu Y; Piquemal, Jean-Philip

    2016-02-15

    We propose a general coupling of the Smooth Particle Mesh Ewald SPME approach for distributed multipoles to a short-range charge penetration correction modifying the charge-charge, charge-dipole and charge-quadrupole energies. Such an approach significantly improves electrostatics when compared to ab initio values and has been calibrated on Symmetry-Adapted Perturbation Theory reference data. Various neutral molecular dimers have been tested and results on the complexes of mono- and divalent cations with a water ligand are also provided. Transferability of the correction is adressed in the context of the implementation of the AMOEBA and SIBFA polarizable force fields in the TINKER-HP software. As the choices of the multipolar distribution are discussed, conclusions are drawn for the future penetration-corrected polarizable force fields highlighting the mandatory need of non-spurious procedures for the obtention of well balanced and physically meaningful distributed moments. Finally, scalability and parallelism of the short-range corrected SPME approach are addressed, demonstrating that the damping function is computationally affordable and accurate for molecular dynamics simulations of complex bio- or bioinorganic systems in periodic boundary conditions. Copyright © 2016 Wiley Periodicals, Inc.

  12. Application of Short-Range LIDAR in Early Alerting for Low-Level Windshear and Turbulence at Hong Kong International Airport

    Directory of Open Access Journals (Sweden)

    K. K. Hon

    2014-01-01

    Full Text Available Hong Kong Observatory currently uses a series of meteorological instruments, including long-range LIDAR (light detection and ranging systems, to provide alerting services of low-level windshear and turbulence for Hong Kong International Airport. For some events that are smaller in spatial dimensions and are rapidly changing, such as low altitude windshear and turbulence associated with buildings or man-made structures, it would be necessary to involve meteorological instruments that offer greater spatial resolution. Therefore, the Observatory has set up a short-range LIDAR on the roof of the AsiaWorld-Expo during the summers over the past several years, conducting field research on the feasibility of strengthening early alerting for windshear and turbulence over the north runway’s eastern arrival runway (Runway 25RA and developing an automated early alerting algorithm. This paper takes the pilot reports for Runway 25RA during the 2013 field research as verification samples, using different thresholds for radial wind velocity spatial and temporal changes detected by the short-range LIDAR to calculate the relative operating characteristic (ROC curve, and analyzes its early alerting performance.

  13. Adaptive Blending of Model and Observations for Automated Short-Range Forecasting: Examples from the Vancouver 2010 Olympic and Paralympic Winter Games

    Science.gov (United States)

    Bailey, Monika E.; Isaac, George A.; Gultepe, Ismail; Heckman, Ivan; Reid, Janti

    2014-01-01

    An automated short-range forecasting system, adaptive blending of observations and model (ABOM), was tested in real time during the 2010 Vancouver Olympic and Paralympic Winter Games in British Columbia. Data at 1-min time resolution were available from a newly established, dense network of surface observation stations. Climatological data were not available at these new stations. This, combined with output from new high-resolution numerical models, provided a unique and exciting setting to test nowcasting systems in mountainous terrain during winter weather conditions. The ABOM method blends extrapolations in time of recent local observations with numerical weather predictions (NWP) model predictions to generate short-range point forecasts of surface variables out to 6 h. The relative weights of the model forecast and the observation extrapolation are based on performance over recent history. The average performance of ABOM nowcasts during February and March 2010 was evaluated using standard scores and thresholds important for Olympic events. Significant improvements over the model forecasts alone were obtained for continuous variables such as temperature, relative humidity and wind speed. The small improvements to forecasts of variables such as visibility and ceiling, subject to discontinuous changes, are attributed to the persistence component of ABOM.

  14. The order parameter and susceptibility of the 3D Ising-like system in an external field near the phase transition point

    Directory of Open Access Journals (Sweden)

    M.P. Kozlovskii

    2010-01-01

    Full Text Available The present work is devoted to the investigation of the 3D Ising-like model in the presence of an external field in the vicinity of critical point. The method of collective variables is used. General expressions for the order parameter and susceptibility are calculated as functions of temperature and the external field as well as scaling functions of that are explicitly obtained. The results are compared with the ones obtained within the framework of parametric representation of the equation of state and Monte Carlo simulations. New expression for the exit point from critical regime of the order parameter fluctuations is proposed and used for the calculation.

  15. Parameter Control of Genetic Algorithms by Learning and Simulation of Bayesian Networks——A Case Study for the Optimal Ordering of Tables

    Institute of Scientific and Technical Information of China (English)

    Concha Bielza; Juan A.Fernández del Pozo; Pedro Larra(n)aga

    2013-01-01

    Parameter setting for evolutionary algorithms is still an important issue in evolutionary computation.There are two main approaches to parameter setting:parameter tuning and parameter control.In this paper,we introduce self-adaptive parameter control of a genetic algorithm based on Bayesian network learning and simulation.The nodes of this Bayesian network are genetic algorithm parameters to be controlled.Its structure captures probabilistic conditional (in)dependence relationships between the parameters.They are learned from the best individuals,i.e.,the best configurations of the genetic algorithm.Individuals are evaluated by running the genetic algorithm for the respective parameter configuration.Since all these runs are time-consuming tasks,each genetic algorithm uses a small-sized population and is stopped before convergence.In this way promising individuals should not be lost.Experiments with an optimal search problem for simultaneous row and column orderings yield the same optima as state-of-the-art methods but with a sharp reduction in computational time.Moreover,our approach can cope with as yet unsolved high-dimensional problems.

  16. Short-range spatial variability of soil δ15N natural abundance – effects on symbiotic N2-fixation estimates in pea

    DEFF Research Database (Denmark)

    Holdensen, Lars; Hauggaard-Nielsen, Henrik; Jensen, Erik Steen

    2007-01-01

    abundance in spring barley and N2-fixing pea was measured within the 0.15-4 m scale at flowering and at maturity. The short-range spatial variability of soil δ15N natural abundance and symbiotic nitrogen fixation were high at both growth stages. Along a 4-m row, the δ15N natural abundance in barley......-abundance are that estimates of symbiotic N2-fixation can be obtained from the natural abundance method if at least half a square meter of crop and reference plants is sampled for the isotopic analysis. In fields with small amounts of representative reference crops (weeds) it might be necessary to sow in reference crop...

  17. Solvent-shared pairs of densely charged ions induce intense but short-range supra-additive slowdown of water rotation.

    Science.gov (United States)

    Vila Verde, Ana; Santer, Mark; Lipowsky, Reinhard

    2016-01-21

    The question "Can ions exert supra-additive effects on water dynamics?" has had several opposing answers from both simulation and experiment. We address this ongoing controversy by investigating water reorientation in aqueous solutions of two salts with large (magnesium sulfate) and small (cesium chloride) effects on water dynamics using molecular dynamics simulations and classical, polarizable models. The salt models are reparameterized to reproduce properties of both dilute and concentrated solutions. We demonstrate that water rotation in concentrated MgSO4 solutions is unexpectedly slow, in agreement with experiment, and that the slowdown is supra-additive: the observed slowdown is larger than that predicted by assuming that the resultant of the extra forces induced by the ions on the rotating water molecules tilts the free energy landscape associated with water rotation. Supra-additive slow down is very intense but short-range, and is strongly ion-specific: in contrast to the long-range picture initially proposed based on experiment, we find that intense supra-additivity is limited to water molecules directly bridging two ions in solvent-shared ion pair configuration; in contrast to a non-ion-specific origin to supra-additive effects proposed from simulations, we find that the magnitude of supra-additive slowdown strongly depends on the identity of the cations and anions. Supra-additive slowdown of water dynamics requires long-lived solvent-shared ion pairs; long-lived ion pairs should be typical for salts of multivalent ions. We discuss the origin of the apparent disagreement between the various studies on this topic and show that the short-range cooperative slowdown scenario proposed here resolves the existing controversy.

  18. Identification of the same polyomavirus species in different African horseshoe bat species is indicative of short-range host-switching events.

    Science.gov (United States)

    Carr, Michael; Gonzalez, Gabriel; Sasaki, Michihito; Dool, Serena E; Ito, Kimihito; Ishii, Akihiro; Hang'ombe, Bernard M; Mweene, Aaron S; Teeling, Emma C; Hall, William W; Orba, Yasuko; Sawa, Hirofumi

    2017-10-06

    Polyomaviruses (PyVs) are considered to be highly host-specific in different mammalian species, with no well-supported evidence for host-switching events. We examined the species diversity and host specificity of PyVs in horseshoe bats (Rhinolophus spp.), a broadly distributed and highly speciose mammalian genus. We annotated six PyV genomes, comprising four new PyV species, based on pairwise identity within the large T antigen (LTAg) coding region. Phylogenetic comparisons revealed two instances of highly related PyV species, one in each of the Alphapolyomavirus and Betapolyomavirus genera, present in different horseshoe bat host species (Rhinolophus blasii and R. simulator), suggestive of short-range host-switching events. The two pairs of Rhinolophus PyVs in different horseshoe bat host species were 99.9 and 88.8 % identical with each other over their respective LTAg coding sequences and thus constitute the same virus species. To corroborate the species identification of the bat hosts, we analysed mitochondrial cytb and a large nuclear intron dataset derived from six independent and neutrally evolving loci for bat taxa of interest. Bayesian estimates of the ages of the most recent common ancestors suggested that the near-identical and more distantly related PyV species diverged approximately 9.1E4 (5E3-2.8E5) and 9.9E6 (4E6-18E6) years before the present, respectively, in contrast to the divergence times of the bat host species: 12.4E6 (10.4E6-15.4E6). Our findings provide evidence that short-range host-switching of PyVs is possible in horseshoe bats, suggesting that PyV transmission between closely related mammalian species can occur.

  19. Comparison of the Tritium permeated from ITER Blanket in normal operation and its short range impact of HT over France, Swiss or Spain

    Energy Technology Data Exchange (ETDEWEB)

    Castro, P.; Velarde, M.; Ardao, J.; Perlado, J.; Sedano, L.; Xiberta, J.

    2015-07-01

    In this paper we assumes the hydrogen isotopes permeation from a liquid metal ITER breeder blanket (assuming normal operation and a LM as DCLL or HCLL blanket) as one of the possible sources of a leak and tritium release,mainly but not only. The paper presents a short range low impact of HT gas activity over France, Swiss or Spain from same cases in 2014 and 2015 releases from ITER. The permeation of hydrogen isotopes is an important experimental issue to take into account into the development of a Tritium Breeder Module for ITER [1]. Tritium cannot be confined -without an uncertainty of 5% in the flux permeation- and therefore HT can be detected (e.g. by ionization chamber) as permeates though the structure of RAFM steel towards the coolant [1]. HT from Pb15.7Li and permeated in Eurofer97 can contaminate the other parts of the system and may be delivered though the normal-vent detritiation system (NVDS). Real time forecast of transport of tritium in air from the fusion reactor towards off-site far downwind though extended tritium clouds into the low levels of the atmosphere is calculated for the short range (up to 24 hours) by the coupling of 2 models the European Centre for Medium Range Weather Forecast (ECMWF) [2] model and the FLEXPART lagrangian dispersion model [3] verified with NORMTRI simulation [4] and implemented in many different cases and scenarios [5, 6, 7]. As a function of daily weather conditions the release will affect just France or already can be delivered towards Swiss when cyclonic circulation, or towards the Iberian Peninsula or Balearic Islands (Spain) when high produce anticyclonic circulation of the air over the Mediterranean Sea. (Author)

  20. Experimental parameters optimization of instrumental neutron activation analysis in order to determine selected elements in some industrial soils in Turkey

    International Nuclear Information System (INIS)

    Haciyakupoglu, Sevilay; Nur Esen, Ayse; Erenturk, Sema

    2014-01-01

    The purpose of this study is optimization of the experimental parameters for analysis of soil matrix by instrumental neutron activation analysis and quantitative determination of barium, cerium, lanthanum, rubidium, scandium and thorium in soil samples collected from industrialized urban areas near Istanbul. Samples were irradiated in TRIGA MARK II Research Reactor of Istanbul Technical University. Two types of reference materials were used to check the accuracy of the applied method. The achieved results were found to be in compliance with certified values of the reference materials. The calculated E n numbers for mentioned elements were found to be less than 1. The presented data of element concentrations in soil samples will help to trace the pollution as an impact of urbanization and industrialization, as well as providing database for future studies. - Highlights: • Optimization of experimental parameters is important for high sensitivity results by INAA. • Assessment of uncertainty sources is necessary to increase reliability of results. • The aim of this study is to determine a number of elements in industrial soil samples. • The higher concentrations of studied elements are due to rapid industrialization. • This baseline data can be used in future studies for other industrial areas