Science.gov

Sample records for emission channeling lattice

  1. Lattice QCD simulations of the Zc+ channel

    NASA Astrophysics Data System (ADS)

    Prelovsek, Sasa; Lang, C. B.; Leskovec, Luka; Mohler, Daniel

    2016-01-01

    We discuss the lattice QCD simulations that search for the Zc+ with the unconventional quark content c ¯c d ¯u in the channel IG(JPC) = 1+(1+-). The major challenge is due to the two-meson states J /Ψ π , Ψ2 Sπ , Ψ1 Dπ , D D¯*, D *D¯*, ηcρ that are also inevitably present in this channel. The available lattice simulations find expected two-meson eigenstates, but no additional eigenstate as a candidate for Zc+ . This is in a striking contrast to the lattice results in the flavour non-exotic channels, where additional states are found in relation to most of the known resonances and bound states.

  2. Helical Floquet Channels in 1D Lattices

    NASA Astrophysics Data System (ADS)

    Budich, Jan Carl; Hu, Ying; Zoller, Peter

    2017-03-01

    We show how dispersionless channels exhibiting perfect spin-momentum locking can arise in a 1D lattice model. While such spectra are forbidden by fermion doubling in static 1D systems, here we demonstrate their appearance in the stroboscopic dynamics of a periodically driven system. Remarkably, this phenomenon does not rely on any adiabatic assumptions, in contrast to the well known Thouless pump and related models of adiabatic spin pumps. The proposed setup is shown to be experimentally feasible with state-of-the-art techniques used to control ultracold alkaline earth atoms in optical lattices.

  3. Lattice Boltzmann method and channel flow

    NASA Astrophysics Data System (ADS)

    Stensholt, Sigvat; Mongstad Hope, Sigmund

    2016-07-01

    Lattice Boltzmann methods are presented at an introductory level with a focus on fairly simple simulations that can be used to test and illustrate the model’s capabilities. Two scenarios are presented. The first is a simple laminar flow in a straight channel driven by a pressure gradient (Poiseuille flow). The second is a more complex, including a wedge where Moffatt vortices may be induced if the wedge is deep enough. Simulations of the Poiseuille flow scenario accurately capture the theoretical velocity profile. The experiment shows the location of the fluid-wall boundary and the effects viscosity has on the velocity and convergence time. The numerical capabilities of the lattice Boltzmann model are tested further by simulating the more complex Moffatt vortex scenario. The method reproduces with high accuracy the theoretical predction that Moffat vortices will not form in a wedge if the vertex angle exceeds 146°. Practical issues limitations of the lattice Boltzmann method are discussed. In particular the accuracy of the bounce-back boundary condition is first order dependent on the grid resolution.

  4. Coupled-channel scattering in 1 + 1 dimensional lattice model

    SciTech Connect

    Guo, Peng

    2013-07-01

    Based on the Lippmann-Schwinger equation approach, a generalized Lüscher’s formula in 1+1 dimensions for two particles scattering in both the elastic and coupled-channel cases in moving frames is derived. A two-dimensional coupled-channel scattering lattice model is presented, which represents a two-coupled-channel resonant scattering scalars system. The Monte Carlo simulation is performed on finite lattices and in various moving frames. The two-dimensional generalized Lüscher’s formula is used to extract the scattering amplitudes for the coupled-channel system from the discrete finite-volume spectrum.

  5. Size Dependent Cation Channel in Nanoporous Prussian Blue Lattice

    NASA Astrophysics Data System (ADS)

    Moritomo, Yutaka; Igarashi, Kazuhiro; Kim, Jungeun; Tanaka, Hiroshi

    2009-08-01

    Cation and/or molecule transfer within nanoporous materials can be utilized in, for example, electrochromic devices, hydrogen storage, molecular sensors, and molecular filters. Here, we investigated the mobilities of cations, Na+, K+, and Rb+, in vacancy-controlled Prussian blue film, NaxCo[Fe(CN)6]1-vzH2O (v is vacancy concentration) with a jungle gym structure. We found that only the smallest Na+ ions pass through the cubic planes of the lattice, while the larger cations, i.e., K+ and Rb+, take a detour channel along the [Fe(CN)6] vacancy. The size-dependent cation channel is well understood in terms of the potential curve derived by an ab initio total energy calculation.

  6. Diagonal composite order in a two-channel Kondo lattice.

    PubMed

    Hoshino, Shintaro; Otsuki, Junya; Kuramoto, Yoshio

    2011-12-09

    A novel type of symmetry breaking is reported for the two-channel Kondo lattice where conduction electrons have spin and orbital (channel) degrees of freedom. Using the continuous-time quantum Monte Carlo and the dynamical mean-field theory, a spontaneous breaking of the orbital symmetry is observed. The tiny breakdown of orbital occupation number, however, vanishes if the conduction electrons have the particle-hole symmetry. The proper order parameter instead is identified as a composite quantity representing the orbital-selective Kondo effect. The single-particle spectrum of the selected orbital shows insulating property, while the other orbital behaves as a Fermi liquid. This composite order is the first example of odd-frequency order other than off-diagonal order (superconductivity), and is a candidate of hidden order in f-electron systems.

  7. Study of the $Z_c^+$ channel in lattice QCD

    SciTech Connect

    Leskovec, Luka; Prelovsek, Sasa; Lang, C. B.; Mohler, Daniel

    2015-04-11

    Several charged charmonium-like hadrons called $Z_c$ have been recently discovered by different experiments. In contrast to conventional hadrons these contain at least two valence quarks and antiquarks ($\\bar{c}c\\bar{d}u$). We perform a lattice QCD simulation of the $I^G(J^{PC})=1^+(1^{+-})$ channel including all relevant two-meson operators under 4.3 GeV: $J/\\psi \\pi$, $\\psi_{2S}\\pi$, $\\psi_{1D}\\pi$, $D \\bar{D}^*$, $D^* \\bar{D}^*$, $\\eta_c \\rho$ as well as additional diquark anti-diquark operators. In our $N_f = 2$ simulation with pion mass at 266 MeV we are able to identify all two-meson levels within the energy region of interest. However we find no additional level identifiable as a candidate for $Z_c$.

  8. Cubic lattice nanosheets: thickness-driven light emission.

    PubMed

    Golberg, Dmitri; Zhang, Chao; Xu, Zhi

    2014-07-22

    Silicon has a diamond-like cubic crystal lattice for which two-dimensional (2D) nanometer thickness nanosheet crystallization appears not to be trivial. However, in this issue of ACS Nano, the group led by Heon-Jin Choi demonstrates the gas-phase dendritic growth of Si nanosheets, only 1 to 13 nm thick. Moreover, such nanosheets display strong thickness-dependent photoluminescence in a visible range with red, green, and blue emission each documented.

  9. A versatile apparatus for on-line emission channeling experiments

    SciTech Connect

    Silva, M. R.; Wahl, U.; Correia, J. G.

    2013-07-15

    The concept and functionality of an apparatus dedicated to emission channeling experiments using short-lived isotopes on-line at ISOLDE/CERN is described. The setup is assembled in two functional blocks – (a) base stand including beam collimation, implantation and measurement chamber, cryogenic extension, and vacuum control system and (b) Panmure goniometer extension including maneuvering cradle and sample heating furnace. This setup allows for in situ implantation and sample analysis in the as-implanted state and upon cooling down to 50 K and during annealing up to 1200 K. The functionality of the setup will be illustrated with the example of establishing the lattice location of {sup 56}Mn probes implanted into GaAs.

  10. A versatile apparatus for on-line emission channeling experiments.

    PubMed

    Silva, M R; Wahl, U; Correia, J G; Amorim, L M; Pereira, L M C

    2013-07-01

    The concept and functionality of an apparatus dedicated to emission channeling experiments using short-lived isotopes on-line at ISOLDE∕CERN is described. The setup is assembled in two functional blocks - (a) base stand including beam collimation, implantation and measurement chamber, cryogenic extension, and vacuum control system and (b) Panmure goniometer extension including maneuvering cradle and sample heating furnace. This setup allows for in situ implantation and sample analysis in the as-implanted state and upon cooling down to 50 K and during annealing up to 1200 K. The functionality of the setup will be illustrated with the example of establishing the lattice location of (56)Mn probes implanted into GaAs.

  11. Competing pairing channels in the doped honeycomb lattice Hubbard model

    NASA Astrophysics Data System (ADS)

    Xu, Xiao Yan; Wessel, Stefan; Meng, Zi Yang

    2016-09-01

    Proposals for superconductivity emerging from correlated electrons in the doped Hubbard model on the honeycomb lattice range from chiral d +i d singlet to p +i p triplet pairing, depending on the considered range of doping and interaction strength, as well as the approach used to analyze the pairing instabilities. Here, we consider these scenarios using large-scale dynamic cluster approximation (DCA) calculations to examine the evolution in the leading pairing symmetry from weak to intermediate coupling strength. These calculations focus on doping levels around the van Hove singularity (VHS) and are performed using DCA simulations with an interaction-expansion continuous-time quantum Monte Carlo cluster solver. We calculated explicitly the temperature dependence of different uniform superconducting pairing susceptibilities and found a consistent picture emerging upon gradually increasing the cluster size: while at weak coupling the d +i d singlet pairing dominates close to the VHS filling, an enhanced tendency towards p -wave triplet pairing upon further increasing the interaction strength is observed. The relevance of these systematic results for existing proposals and ongoing pursuits of odd-parity topological superconductivity are also discussed.

  12. Mass-Imbalanced Superconductivity in Effective Two-Channel Kondo Lattice

    NASA Astrophysics Data System (ADS)

    Kusunose, Hiroaki

    2016-11-01

    We propose that mass-imbalanced superconductivity is realized in an effective two-channel Kondo lattice, and its characteristic property appears in electromagnetic responses such as the Meissner effect. Starting from an effective two-channel Kondo lattice model as a low-energy effective theory, and approximating it with two mean-field order parameter components in a self-consistent fashion, it is shown that the balance of the two components is sensitively reflected in the magnitude of the Meissner kernel, while thermodynamic properties are little affected by the balance. This remarkable behavior is understood by the localized character of one partner in the Cooper pair, namely, the effect of the mass imbalance. We briefly mention the relevance to the huge enhancement of the upper critical field under pressure observed in Pr 1-2-20 systems.

  13. Drag reduction in a channel with microstructure grooves using the lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Daeian, M. A.; Moosavi, A.; Nouri-Borujerdi, A.; Taghvaei, E.

    2017-03-01

    Using the Shan–Chen lattice Boltzmann multi-phase model, we investigate the effect of adding microstructured grooves to the walls of a 2D parallel-plate channel on the pressure drop in the channel. The effects of the size of the grooves on the pressure drop in the channel were considered. It was observed that the pitch of the grooves has a considerable effect on the pressure drop in the channel, and even for some values of the pitch we observe an increase in the pressure drop. As the pitch decreases, a lower pressure drop is achieved. The results also show that as the ratio of the solid–liquid contact surface to the whole surface is decreased, the pressure drop decreases. It is also observed that the grooves should be deep enough to yield drag reduction, otherwise it would have a negative effect.

  14. Crystallization of a Keplerate-type polyoxometalate into a superposed kagome-lattice with huge channels.

    PubMed

    Saito, Masaki; Ozeki, Tomoji

    2012-09-07

    Crystal structures of two Sr(2+) salts of the Keplerate-type polyoxometalate, [Mo(VI)(72)Mo(V)(60)O(372)(CH(3)COO)(30)(H(2)O)(72)](42-), have been determined by single crystal X-ray diffraction. One compound exhibits a superposed kagome-lattice with huge channels whose diameters measure approximately 3.0 nm, while the arrangement of the Keplerate anions in the other compound approximates to a distorted cubic close packing.

  15. Resonant emission of solitons from impurity-induced localized waves in nonlinear lattices.

    PubMed

    Yu, Gaokun; Wang, Xinlong; Tao, Zhiyong

    2011-02-01

    We propose a mechanism for soliton creation from resonantly excited localized waves via supratransmission in band gaps of nonlinear lattices. A nonlinear localized wave, which is formed by and vibrates around an impurity with an intrinsic frequency, is found to undergo a local resonance when subject to an external forcing. Under the resonance, an instability develops that leads to the efficient emission of solitons at a much lower rate than that in uniform lattices with no impurity. ©2011 American Physical Society

  16. Superconductivity of composite particles in a two-channel Kondo lattice.

    PubMed

    Hoshino, Shintaro; Kuramoto, Yoshio

    2014-04-25

    Emergence of odd-frequency s-wave superconductivity is demonstrated in the two-channel Kondo lattice by means of the dynamical mean-field theory combined with the continuous-time quantum Monte Carlo method. Around half filling of the conduction bands, divergence of an odd-frequency pairing susceptibility is found, which signals instability toward the superconductivity. The corresponding order parameter is equivalent to a staggered composite-pair amplitude with even frequencies, which involves both localized spins and conduction electrons. A model wave function is constructed for the composite order with the use of symmetry operations such as charge conjugation and channel rotations. Given a certain asymmetry of the conduction bands, another s-wave superconductivity is found that has a uniform order parameter. The Kondo effect in the presence of two channels is essential for both types of unconventional superconductivity.

  17. Pion-nucleon scattering in the Roper channel from lattice QCD

    DOE PAGES

    Lang, Christian B.; Leskovec, L.; Padmanath, M.; ...

    2017-01-31

    We present a lattice QCD study ofmore » $$N\\pi$$ scattering in the positive-parity nucleon channel, where the puzzling Roper resonance $N^*(1440)$ resides in experiment. The study is based on the PACS-CS ensemble of gauge configurations with $$N_f=2+1$$ Wilson-clover dynamical fermions, $$m_\\pi \\simeq 156~$$MeV and $$L\\simeq 2.9~$$fm. In addition to a number of $qqq$ interpolating fields, we implement operators for $$N\\pi$$ in $p$-wave and $$N\\sigma$$ in $s$-wave. In the center-of-momentum frame we find three eigenstates below 1.65 GeV. They are dominated by $N(0)$, $$N(0)\\pi(0)\\pi(0)$$ (mixed with $$N(0)\\sigma(0)$$) and $$N(p)\\pi(-p)$$ with $$p\\simeq 2\\pi/L$$, where momenta are given in parentheses. This is the first simulation where the expected multi-hadron states are found in this channel. The experimental $$N\\pi$$ phase-shift would -- in the approximation of purely elastic $$N\\pi$$ scattering -- imply an additional eigenstate near the Roper mass $$m_R\\simeq 1.43~$$GeV for our lattice size. We do not observe any such additional eigenstate, which indicates that $$N\\pi$$ elastic scattering alone does not render a low-lying Roper. Coupling with other channels, most notably with $$N\\pi\\pi$$, seems to be important for generating the Roper resonance, reinforcing the notion that this state could be a dynamically generated resonance. Our results are in line with most of previous lattice studies based just on $qqq$ interpolators, that did not find a Roper eigenstate below $1.65~$GeV. As a result, the study of the coupled-channel scattering including a three-particle decay $$N\\pi\\pi$$ remains a challenge.« less

  18. Pion-nucleon scattering in the Roper channel from lattice QCD

    NASA Astrophysics Data System (ADS)

    Lang, C. B.; Leskovec, L.; Padmanath, M.; Prelovsek, S.

    2017-01-01

    We present a lattice QCD study of N π scattering in the positive-parity nucleon channel, where the puzzling Roper resonance N*(1440 ) resides in experiment. The study is based on the PACS-CS ensemble of gauge configurations with Nf=2 +1 Wilson-clover dynamical fermions, mπ≃156 MeV and L ≃2.9 fm . In addition to a number of q q q interpolating fields, we implement operators for N π in p -wave and N σ in s -wave. In the center-of-momentum frame we find three eigenstates below 1.65 GeV. They are dominated by N (0 ), N (0 )π (0 )π (0 ) [mixed with N (0 )σ (0 )] and N (p )π (-p ) with p ≃2 π /L , where momenta are given in parentheses. This is the first simulation where the expected multi-hadron states are found in this channel. The experimental N π phase shift would—in the approximation of purely elastic N π scattering—imply an additional eigenstate near the Roper mass mR≃1.43 GeV for our lattice size. We do not observe any such additional eigenstate, which indicates that N π elastic scattering alone does not render a low-lying Roper. Coupling with other channels, most notably with N π π , seems to be important for generating the Roper resonance, reinforcing the notion that this state could be a dynamically generated resonance. Our results are in line with most of the previous lattice studies based just on q q q interpolators, which did not find a Roper eigenstate below 1.65 GeV. The study of the coupled-channel scattering including a three-particle decay N π π remains a challenge.

  19. Emission difference super-resolution microscopy with optical lattices scanning and wide field detection

    NASA Astrophysics Data System (ADS)

    Zhu, Dazhao; Chen, Youhua; Kuang, Cuifang; Liu, Xu

    2017-07-01

    A parallel scanning method using optical lattices is proposed theoretically to improve the imaging speed of fluorescence emission difference microscopy (FED), which gives the wide field imaging capability to FED while maintaining all the basic advantages of single point FED. The basic principle of wide field FED (wfFED) is presented briefly and the method of generating optical lattices is discussed. The resolution via two types of optical lattices pattern scanning is also studied. With optical lattices scanning, which is generated by two orthogonally crossed standing waves, the wfFED can be implemented without wide field excitation. This strategy can further improve the wfFED imaging speed and simplify the set-up.

  20. Propagation of monopole defects and flux channels in an artificial square spin-ice lattice

    NASA Astrophysics Data System (ADS)

    Zhu, Yimei; Volkov, V. V.; Pollard, Shawn

    2012-02-01

    The recent development of artificial lattices of magnetic islands in which competing interactions give rise to macroscopic analogs of atomically frustrated spin ices has opened up a new field of research, in which the interaction, frustration and evolution of individual magnetic elements can be directly observed in real space. We investigate the magnetic reversal along the (11) symmetry axis of permalloy islands in an artificial ``square'' spin-ice geometry with in-situ Lorentz transmission electron microscopy. Novel differential transport-of-intensity allows for the identification of ``monopole''-like defects and flux channels, similar to Dirac strings, that link them. We track the growth and propagation of these defects and flux channels throughout the reversal process. Simulations are used to compare with experiment to show how nucleation and propagation of defects affect the reversal of the lattice as a whole. We find that interactions between defects and flux channels can explain the saturation of defect populations at low net magnetizations. This work was supported by U.S. Department of Energy, Office of Basic Energy Science, Material Sciences and Engineering Division, under Contract No. DE-AC02-98CH10886.

  1. Plasmonic emission and plasma lattice structures induced by pulsed laser in Purcell cavity on silicon

    NASA Astrophysics Data System (ADS)

    Huang, Wei-Qi; Huang, Zhong-Mei; Miao, Xin-Jian; Liu, Shi-Rong; Qin, Chao-Jian

    2015-10-01

    The lattice structure image of a plasma standing wave in a Purcell cavity of silicon is observed. The plasma wave produced by the pulsed laser could be used to fabricate the micro-nanostructure of silicon. The plasma lattice structures induced by the nanosecond pulsed laser in the cavity may be similar to the Wigner crystal structure. It is interesting that the beautiful diffraction pattern could be observed in the plasma lattice structure. The radiation lifetime could be shortened to the nanosecond range throughout the entire spectral range and the relaxation time could be lengthened for higher emission efficiency in the Purcell cavity, which results in the fact that the plasmonic emission is stronger and its threshold is lower. Project supported by the National Natural Science Foundation of China (Grant Nos. 11264007 and 61465003).

  2. Lattice Boltzmann simulations of liquid crystal particulate flow in a channel with finite anchoring boundary conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Roberts, Tyler; de Pablo, Juan; dePablo Team

    2014-11-01

    Liquid crystals (LC) posses anisotropic viscoelastic properties, and, as such, LC flow can be incredibly complicated. Here we employ a hybrid lattice Boltzmann method (pioneered by Deniston, Yeomans and Cates) to systematically study the hydrodynamics of nematic liquid crystals (LCs) with and without solid particles. This method evolves the velocity field through lattice Boltzmann and the LC-order parameter via a finite-difference solver of the Beris-Edwards equation. The evolution equation of the boundary points with finite anchoring is obtained through Poisson bracket formulation. Our method has been validated by matching the Ericksen-Leslie theory. We demonstrate two applications in the flow alignment regime. We first investigate a hybrid channel flow in which the top and bottom walls have different anchoring directions. By measuring the apparent shear viscosity in terms of Couette flow, we achieve a viscosity inhomogeneous system which may be applicable to nano particle processing. In the other example, we introduce a homeotropic spherical particle to the channel, and focus on the deformations of the defect ring due to anchorings and flow. The results are then compared to the molecular dynamics simulations of a colloid particle in an LC modeled by a Gay-Berne potential.

  3. Ion channeling study of lattice distortions in chromium-doped SrTiO3 crystals

    NASA Astrophysics Data System (ADS)

    Lavrentiev, V.; Vacik, J.; Dejneka, A.; Trepakov, V.; Jastrabik, L.

    2013-07-01

    The results of ion channeling studies of lattice distortions in SrTiO3: Cr single crystals are presented. Two types of single crystals containing the same amount of Cr impurities but differing in stoichiometry have been investigated. The single crystals grown by the Verneuil method have the compositions of standard-grown SrTiO3: Cr (0.05 at % Cr), whereas the single crystals grown with a strontium deficiency and a chromium compensating amount have the composition Sr0.9995TiO3 (0.05 at % Cr). Analysis of the angular channeling spectra indicates that, in crystals of both types, the main defects are Cr impurities located in octahedral sites. In the SrTiO3: Cr crystals, impurity atoms manifest themselves as Cr4+ with tetragonal Jahn-Teller distortions of the surrounding lattice. In the Sr0.9995TiO3: Cr crystals grown with a Sr deficiency, the characteristic displacements of Ti ions in the third coordination sphere of the Jahn-Teller center Cr4+ exhibit the effect of interaction of the center with a neighboring vacancy in the Sr sublattice.

  4. Three-Dimensional Analysis of the Lattice Confinement Effect on Ion Dynamics in Condensed Matter and Lattice Effect on the D-D Nuclear Reaction Channel

    SciTech Connect

    Violante, Vittorio; Torre, Amalia; Selvaggi, Giovanna; Miley, George H.

    2001-03-15

    A three-dimensional analysis of the dynamics of hydrogen isotopes confined within a metal lattice, like palladium or nickel, is presented. It is assumed that the concentration of the hydrogen isotopes, as an atomic fraction, is close to unity and that coherent oscillations of the metal atom electrons near to the Fermi level take place. Coherent oscillations of the Fermi-level electrons in the metal lattice can produce an oscillating electric field within the cell and hence produce a radio-frequency oscillation of ions like protons or deuterons. The trajectories of the ions can be studied by means of the equations of motion. The results show that under proper initial conditions, the closest distance of approach between two ions or between an ion and the nucleus of an atom of the host metal lattice can be reduced below 0.1 Angst. An evaluation of the excess of heat production has been done for the D-D reaction within a Pd lattice by approximating the reaction both to an s-wave and a d-wave process, respectively. Last, the effect of the lattice field, which causes the collisions between ions, on the nuclear reaction channel for the D-D reaction is investigated by evaluating the transition probability for a stimulated decay.

  5. Plasmonic lattice resonance-enhanced light emission from plastic scintillators by periodical Ag nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Zhu, Zhichao; Wu, Qiang; Cheng, Chuanwei; Gu, Mu; Xu, Jun; Chen, Hong; Liu, Jinliang; Chen, Liang; Ouyang, Xiaoping

    2017-05-01

    We have demonstrated that periodical arrays of silver nanoparticles can enhance the light emission from a plastic scintillator layer on the surface of a silicon substrate. The enhancement is attributed to surface lattice resonances with a photonic-plasmonic nature. Although the enhancement exhibits directional characteristics for individual wavelengths, the wavelength-integrated enhancement shows a monotonous increase with increasing emission angle. As a result, an overall 1.81-fold wavelength- and angle-integrated enhancement has been obtained. This observation is promising for fundamental and applied research into enhanced luminescent material layers on opaque substrates.

  6. Search for Zc+(3900) in the 1 channel on the lattice

    NASA Astrophysics Data System (ADS)

    Prelovsek, Sasa; Leskovec, Luka

    2013-11-01

    Recently three experiments reported a discovery of manifestly exotic Zc+(3900) in the decay to J/ψπ+, while J and P are experimentally unknown. We search for this state on the lattice by simulating the channel with JPC=1 and I=1, and we do not find a candidate for Zc+(3900). Instead, we only find discrete scattering states DD and J/ψπ, which inevitably have to be present in a dynamical QCD. The possible reasons for not finding Zc+ may be that its quantum numbers are not 1 or that the employed interpolating fields are not diverse enough. Simulations with additional types of interpolators will be needed to reach a more definite conclusion.

  7. Coupled lattice-Boltzmann and finite-difference simulation of electroosmosis in microfluidic channels

    NASA Astrophysics Data System (ADS)

    Hlushkou, Dzmitry; Kandhai, Drona; Tallarek, Ulrich

    2004-10-01

    In this article we are concerned with an extension of the lattice-Boltzmann method for the numerical simulation of three-dimensional electroosmotic flow problems in porous media. Our description is evaluated using simple geometries as those encountered in open-channel microfluidic devices. In particular, we consider electroosmosis in straight cylindrical capillaries with a (non)uniform zeta-potential distribution for ratios of the capillary inner radius to the thickness of the electrical double layer from 10 to 100. The general case of heterogeneous zeta-potential distributions at the surface of a capillary requires solution of the following coupled equations in three dimensions: Navier-Stokes equation for liquid flow, Poisson equation for electrical potential distribution, and the Nernst-Planck equation for distribution of ionic species. The hydrodynamic problem has been treated with high efficiency by code parallelization through the lattice-Boltzmann method. For validation velocity fields were simulated in several microcapillary systems and good agreement with results predicted either theoretically or obtained by alternative numerical methods could be established. Results are also discussed with respect to the use of a slip boundary condition for the velocity field at the surface.

  8. Simulation of mixed convection in a horizontal channel heated from below by the lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Sahraoui, Nassim M.; Houat, Samir; Saidi, Nawal

    2017-05-01

    We perform a contribution with a simulation study of the mixed convection in horizontal channel heated from below. The lattice Boltzmann method (LBM) is used with the Boussinesq approximation to solve the coupled phenomenon that governs the systems thermo-hydrodynamics. The double populations thermal lattice Boltzmann model (TLBM) is used with the D2Q5 for the thermal field and D2Q9 model for the dynamic field. A comparison of the results of the averaged Nusselt number obtained by the TLBM with other references is presented for an area stretching. The streamlines, the vortices, the isotherms, the velocity profiles and other parameters of the study, are presented at a certain time tT which is chosen arbitrarily. The results presented here are in good agreement with those reported in the scientific literature which gives us high expectations about the reliability of the TLBM to simulate this kind of physical phenomena. Contribution to the topical issue "Materials for Energy harvesting, conversion and storage II (ICOME 2016)", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  9. Electrical Conductivity, Thermal Stability, and Lattice Defect Evolution During Cyclic Channel Die Compression of OFHC Copper

    NASA Astrophysics Data System (ADS)

    Satheesh Kumar, S. S.; Raghu, T.

    2015-02-01

    Oxygen-free high-conductivity (OFHC) copper samples are severe plastically deformed by cyclic channel die compression (CCDC) technique at room temperature up to an effective plastic strain of 7.2. Effect of straining on variation in electrical conductivity, evolution of deformation stored energy, and recrystallization onset temperatures are studied. Deformation-induced lattice defects are quantified using three different methodologies including x-ray diffraction profile analysis employing Williamson-Hall technique, stored energy based method, and electrical resistivity-based techniques. Compared to other severe plastic deformation techniques, electrical conductivity degrades marginally from 100.6% to 96.6% IACS after three cycles of CCDC. Decrease in recrystallization onset and peak temperatures is noticed, whereas stored energy increases and saturates at around 0.95-1.1J/g after three cycles of CCDC. Although drop in recrystallization activation energy is observed with the increasing strain, superior thermal stability is revealed, which is attributed to CCDC process mechanics. Low activation energy observed in CCDC-processed OFHC copper is corroborated to synergistic influence of grain boundary characteristics and lattice defects distribution. Estimated defects concentration indicated continuous increase in dislocation density and vacancy with strain. Deformation-induced vacancy concentration is found to be significantly higher than equilibrium vacancy concentration ascribed to hydrostatic stress states experienced during CCDC.

  10. Lattice Boltzmann method simulations of Stokes number effects on particle motion in a channel flow

    NASA Astrophysics Data System (ADS)

    Zhang, Lenan; Jebakumar, Anand Samuel; Abraham, John

    2016-06-01

    In a recent experimental study by Lau and Nathan ["Influence of Stokes number on the velocity and concentration distributions in particle-laden jets," J. Fluid Mech. 757, 432 (2014)], it was found that particles in a turbulent pipe flow tend to migrate preferentially toward the wall or the axis depending on their Stokes number (St). Particles with a higher St (>10) are concentrated near the axis while those with lower St (<1) move toward the walls. Jebakumar et al. ["Lattice Boltzmann method simulations of Stokes number effects on particle trajectories in a wall-bounded flow," Comput. Fluids 124, 208 (2016)] have carried out simulations of a particle in a laminar channel flow to investigate this behavior. In their work, they report a similar behavior where particles with low St migrate toward the wall and oscillate about a mean position near the wall while those with high St oscillate about the channel center plane. They have explained this behavior in terms of the Saffman lift, Magnus lift, and wall repulsion forces acting on the particle. The present work extends the previous work done by Jebakumar et al. and aims to study the behavior of particles at intermediate St ranging from 10 to 20. It is in this range where the equilibrium position of the particle changes from near the wall to the axis and the particle starts oscillating about the axis. The Lattice Boltzmann method is employed to carry out this study. It is shown that the change in mean equilibrium position is related to increasing oscillations of the particle with mean position near the wall which results in the particle moving past the center plane to the opposite side. The responsible mechanisms are explained in detail.

  11. Coupled-channel Dπ, Dη and {D}_soverline{K} scattering from lattice QCD

    NASA Astrophysics Data System (ADS)

    Moir, Graham; Peardon, Michael; Ryan, Sinéad M.; Thomas, Christopher E.; Wilson, David J.

    2016-10-01

    We present the first lattice QCD study of coupled-channel Dπ, Dη and {D}_soverline{K} scattering in isospin-1/2 in three partial waves. Using distillation, we compute matrices of correlation functions with bases of operators capable of resolving both meson and mesonmeson contributions to the spectrum. These correlation matrices are analysed using a variational approach to extract the finite-volume energy eigenstates. Utilising Lüscher's method and its extensions, we constrain scattering amplitudes in S, P and D-wave as a function of energy. By analytically continuing the scattering amplitudes to complex energies, we investigate the S-matrix singularities. Working at m π ≈ 391 MeV, we find a pole corresponding to a J P = 0+ near-threshold bound state with a large coupling to Dπ. We also find a deeply bound J P = 1- state, and evidence for a J P = 2+ narrow resonance coupled predominantly to Dπ. Elastic Dπ scattering in the isospin-3 /2 channel is studied and we find a weakly repulsive interaction in S-wave.

  12. Lattice Boltzmann simulations of droplet formation in confined channels with thermocapillary flows

    NASA Astrophysics Data System (ADS)

    Gupta, A.; Sbragaglia, M.; Belardinelli, D.; Sugiyama, K.

    2016-12-01

    Based on mesoscale lattice Boltzmann simulations with the "Shan-Chen" model, we explore the influence of thermocapillarity on the breakup properties of fluid threads in a microfluidic T-junction, where a dispersed phase is injected perpendicularly into a main channel containing a continuous phase, and the latter induces periodic breakup of droplets due to the cross-flowing. Temperature effects are investigated by switching on-off both positive-negative temperature gradients along the main channel direction, thus promoting a different thread dynamics with anticipated-delayed breakup. Numerical simulations are performed at changing the flow rates of both the continuous and dispersed phases, as well as the relative importance of viscous forces, surface tension forces, and thermocapillary stresses. The range of parameters is broad enough to characterize the effects of thermocapillarity on different mechanisms of breakup in the confined T-junction, including the so-called "squeezing" and "dripping" regimes, previously identified in the literature. Some simple scaling arguments are proposed to rationalize the observed behavior, and to provide quantitative guidelines on how to predict the droplet size after breakup.

  13. Fully-resolved prolate spheroids in turbulent channel flows: A lattice Boltzmann study

    NASA Astrophysics Data System (ADS)

    Eshghinejadfard, Amir; Hosseini, Seyed Ali; Thévenin, Dominique

    2017-09-01

    Particles are present in many natural and industrial multiphase flows. In most practical cases, particle shape is not spherical, leading to additional difficulties for numerical studies. In this paper, DNS of turbulent channel flows with finite-size prolate spheroids is performed. The geometry includes a straight wall-bounded channel at a frictional Reynolds number of 180 seeded with particles. Three different particle shapes are considered, either spheroidal (aspect ratio λ =2 or 4) or spherical (λ =1 ). Solid-phase volume fraction has been varied between 0.75% and 1.5%. Lattice Boltzmann method (LBM) is used to model the fluid flow. The influence of the particles on the flow field is simulated by immersed boundary method (IBM). In this Eulerian-Lagrangian framework, the trajectory of each particle is computed individually. All particle-particle and particle-fluid interactions are considered (four-way coupling). Results show that, in the range of examined volume fractions, mean fluid velocity is reduced by addition of particles. However, velocity reduction by spheroids is much lower than that by spheres; 2% and 1.6%, compared to 4.6%. Maximum streamwise velocity fluctuations are reduced by addition of particle. By comparing particle and fluid velocities, it is seen that spheroids move faster than the fluid before reaching the same speed in the channel center. Spheres, on the other hand, move slower than the fluid in the buffer layer. Close to the wall, all particle types move faster than the fluid. Moreover, prolate spheroids show a preferential orientation in the streamwise direction, which is stronger close to the wall. Far from the wall, the orientation of spheroidal particles tends to isotropy.

  14. Extended application of lattice Boltzmann method to rarefied gas flow in micro-channels

    NASA Astrophysics Data System (ADS)

    Yuan, Yudong; Rahman, Sheik

    2016-12-01

    Simulation of rarefied gas flow in micro-channels is of great interest owing to its diverse applications in many engineering fields. In this study, a multiple-relaxation-time lattice Boltzmann (MRT-LB) model with a general second-order slip boundary condition is presented to investigate the behaviour of gas flow with a wide range of Knudsen number in micro-channels. With the aid of a Bosanquet-type effective viscosity, the effective relaxation time is correlated with local Knudsen number (Kn) to account for the varying degree of rarefaction effect. Unlike previous studies, the derived accommodation coefficient r for the combined bounce-back/diffusive reflection (CBBDR) boundary condition is dependent on the local Kn, which allows more flexibility to simulate the slip velocity along the channel walls. When compared with results of other methods, such as linearised Boltzmann equation, experimental data, direct simulation Monte Carlo (DSMC) and Information Preservation DSMC (IP-DSMC), it is found that the LB model is capable of capturing the flow behaviour, including the velocity profile, flow rate, pressure distribution and Knudsen minimum of rarefied gas with Kn up to 10. The effect of Knudsen layer (KL) on the velocity of gas flow with a wide range of Kn is also discussed. It is found that KL effect is negligible in the continuum flow and y-independent in the free molecular flow, while in the intermediate range, especially in transition flow, KL effect is significant and particular efforts should be made to capture this effect.

  15. Radiation emission by electrons channeling in bent silicon crystals

    NASA Astrophysics Data System (ADS)

    Polozkov, Roman G.; Ivanov, Vadim K.; Sushko, Gennady B.; Korol, Andrei V.; Solov'yov, Andrey V.

    2014-09-01

    Results of numerical simulations of electron channeling and emission spectra are reported for straight and uniformly bent silicon crystals. The projectile trajectories are computed using the newly developed module [G.B. Sushko, V.G. Bezchastnov, I.A. Solov'yov, A.V. Korol, W. Greiner, A.V. Solov'yov, J. Comput. Phys. 252, 404 (2013)] of the MBN Explorer packageb [I.A. Solov'yov, A.V. Yakubovich, P.V. Nikolaev, I. Volkovets, A.V. Solov'yov, J. Comput. Chem. 33, 2412 (2013)]. The electron channeling along Si(110) crystallographic planes is studied for the projectile energy 855 MeV.

  16. Matter-Wave Emission in Optical Lattices: Single Particle and Collective Effects

    SciTech Connect

    Vega, Ines de; Porras, Diego; Ignacio Cirac, J.

    2008-12-31

    We introduce a simple setup corresponding to the matter-wave analogue of impurity atoms embedded in a photonic crystal and interacting with the radiation field. Atoms in a given internal level are trapped in an optical lattice, and play the role of the impurities. Atoms in an untrapped level play the role of the radiation field. The interaction is mediated by means of lasers that couple those levels. By tuning the lasers parameters, it is possible to drive the system through different regimes, and observe phenomena such as matter-wave superradiance, non-Markovian atom emission, and the appearance of bound atomic states.

  17. Breathing mode lattice relaxation associated with carrier emission and capture by deep electronic levels in silicon

    SciTech Connect

    Samara, G.A.

    1987-01-01

    The breathing mode (volume) lattice relaxations associated with carrier emission and capture are evaluated for a variety of deep levels in silicon using a recently proposed method based on high pressure measurement of the emission rates and capture cross sections. Included are (1) the vacancy-like acceptor levels associated with the oxygen-vacancy pair (or A-center) and the gold, platinum and palladium impurities, (2) the chalcogenide donors in their singly- and doubly-charged states and (3) a number of 3d transition metal donors. The signs and magnitudes (which range from approx.0 to 5A/sup 3//emitted carrier) of these relaxations are discussed in terms of models for the impurities and defects responsible for the associated levels. The results on the chalcogenides are compared with recent theoretical calculations. 8 refs., 1 tab.

  18. Lattice location of O18 in ion implanted Fe crystals by Rutherford backscattering spectrometry, channeling and nuclear reaction analysis

    NASA Astrophysics Data System (ADS)

    Vairavel, Mathayan; Sundaravel, Balakrishnan; Panigrahi, Binaykumar

    2016-09-01

    There are contradictory theoretical predictions of lattice location of oxygen interstitial atom at tetrahedral and octahedral interstices in bcc Fe. For validating these predictions, 300 keV O18 ions with fluence of 5 × 1015 ions/cm2 are implanted into bcc Fe single crystals at room temperature and annealed at 400 °C. The Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA)/channeling measurements are carried out with 850 keV protons. The lattice location of implanted O18 is analysed using the α-particles yield from O18(p,α)N15 nuclear reaction. The tilt angular scans of α-particle yield along <110> and <100> axial directions are performed at room temperature. Lattice location of O18 is found to be at tetrahedral interstitial site by comparing the experimental scan with simulated scans using FLUX7 software.

  19. 78 FR 59903 - Emission Mask Requirements for Digital Technologies on 800 MHz NPSPAC Channels; Analog FM...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-30

    ... From the Federal Register Online via the Government Publishing Office FEDERAL COMMUNICATIONS COMMISSION 47 CFR Part 90 Emission Mask Requirements for Digital Technologies on 800 MHz NPSPAC Channels; Analog FM Capability on Mutual Aid and Interoperability Channels AGENCY: Federal...

  20. All-optical controllable channel-drop filters in two-dimensional square-lattice photonic crystals

    NASA Astrophysics Data System (ADS)

    Fasihi, K.

    2016-05-01

    A novel all-optical controllable channel-drop filter in photonic crystals (PC) of square lattice is presented. We show that using a resonant-cavity-based add-drop filter with a wavelength-selective reflection feedback and a single-control switching module which is based on nonlinear PC microcavities, the dropped channel can be routed to the drop port or returned to the bus waveguide. Using the temporal coupled-mode theory and two-dimensional nonlinear finite-difference time-domain method, the performance of the proposed device is investigated and the simulation results show the validity of the proposed design.

  1. Breathing-mode lattice relaxation accompanying emission and capture by deep electronic levels in silicon

    SciTech Connect

    Samara, G. A.

    1989-05-15

    The breathing-mode (volume) lattice relaxations associated with carrier emission and capture by a variety of deep electronic levels in silicon are evaluated from high-pressure measurements of the emission rates and capture cross sections. Included are (1) the vacancylike acceptor levels associated with the oxygen-vacancy pair (or /ital A/ center) and the gold, platinum, and palladium impurities, (2) the chalcogenide donors in their singly and doubly charged states, (3) a number of 3/ital d/ transition-metal donors, and (4) the phosphorus-vacancy pair (or /ital E/ center) acceptor. The signs and magnitudes (which range from /similar to/0 to 5 A/sup 3//emitted-carrier) of these relaxations are discussed in terms of models for the impurities and defects responsible for the associated levels. The results on the chalcogenides are compared with recent theoretical results. The experimental method used appears to be the only viable experimental method for determining these relaxations which are a direct manifestation of the effective electron-phonon coupling at deep levels and which are important to the understanding of many of the properties of deep levels.

  2. Lattice Boltzmann simulation of fluid flow and heat transfer in a parallel-plate channel with transverse rectangular cavities

    NASA Astrophysics Data System (ADS)

    Mohebbi, Rasul; Heidari, Hanif

    The aim of this paper is investigating the forced convection heat transfer in a channel with transverse rectangular cavities using the lattice Boltzmann method (LBM) which is not available in the literature yet. The effects of the Reynolds number (100-400), cavity aspect ratio (AR=0.25, 0.5, 1.0), distance of cavities from each other (S‧=0,2,4,6) in fixed depth of cavity (A‧=0.5) on the velocity and temperature profiles are studied. Moreover, the flow patterns such as deflection and re-circulation zone inside the cavities are obtained. The local and averaged Nusselt numbers on the channel walls are achieved. The results show that the channel with cavities achieves heat transfer enhancements relative to the smooth channel. For the constant cavity aspect ratio, the maximum value of averaged Nusselt number in the channel is obtained in the case of S‧=2. Heat transfer to the working fluids increases significantly by increasing the aspect ratio. The existed results are used to ascertain the validity of the numerical code and excellent agreement between results was found.

  3. Exact sum rules for vector channel at finite temperature and their application to lattice QCD analysis

    NASA Astrophysics Data System (ADS)

    Satow, Daisuke; Gubler, Philipp

    2017-03-01

    We derive three exact sum rules for the spectral function of the electromagnetic current with zero spatial momentum at finite temperature. Possible applications of the three sum rules to lattice computations of the spectral function and transport coefficients are also discussed: We propose an ansatz for the spectral function that can be applied to all three sum rules and fit it to available lattice data of the Euclidean vector correlator above the critical temperature. As a result, we obtain estimates for both the electrical conductivity σ and the second order transport coefficient τJ.

  4. Methane emissions from sugarcane vinasse storage and transportation systems: Comparison between open channels and tanks

    NASA Astrophysics Data System (ADS)

    Oliveira, Bruna Gonçalves; Carvalho, João Luís Nunes; Chagas, Mateus Ferreira; Cerri, Carlos Eduardo Pellegrino; Cerri, Carlos Clemente; Feigl, Brigitte Josefine

    2017-06-01

    Over the last few years the brazilian sugarcane sector has produced an average of 23.5 million liters of ethanol annually. This scale of production generates large amounts of vinasse, which depending on the manner that is disposed, can result significant greenhouse gas emissions. This study aimed to quantify the methane (CH4) emissions associated with the two most widespread systems of vinasse storage and transportation used in Brazil; open channel and those comprising of tanks and pipes. Additionally, a laboratory incubation study was performed with the aim of isolating the effects of vinasse, sediment and the interaction between these factors on CH4 emissions. We observed significant differences in CH4 emissions between the sampling points along the channels during both years of evaluation (2012-2013). In the channel system, around 80% of CH4 emissions were recorded from uncoated sections. Overall, the average CH4 emission intensity was 1.36 kg CO2eq m-3 of vinasse transported in open channels, which was 620 times higher than vinasse transported through a system of tanks and closed pipes. The laboratory incubation corroborated field results, suggesting that vinasse alone does not contribute significant emissions of CH4. Higher CH4 emissions were observed when vinasse and sediment were incubated together. In summary, our findings demonstrate that CH4 emissions originate through the anaerobic decomposition of organic material deposited on the bottom of channels and tanks. The adoption of coated channels as a substitute to uncoated channels offers the potential for an effective and affordable means of reducing CH4 emissions. Ultimately, the modernization of vinasse storage and transportation systems through the adoption of tank and closed pipe systems will provide an effective strategy for mitigating CH4 emissions generated during the disposal phase of the sugarcane ethanol production process.

  5. Lattice Boltzmann simulation of self-driven bubble transport in a micro-channel with a virtual check valve

    NASA Astrophysics Data System (ADS)

    Chen, Rou; Diao, Wei; Cheng, Yongguang; Zhu, Likun; Yu, Huidan (Whitney)

    2014-11-01

    An innovative self-circulation, self-regulation mechanism has recently been proposed to experimentally generate gaseous species from liquid reactants with little or zero parasitic power consumption. When a bubble grows at a location close to a virtual check valve, expansion of the left meniscus of the bubble is hindered due to its capability to provide a higher capillary pressure than the right meniscus does. We perform numerical simulation of bubble transport in a channel with a virtual check valve using lattice Boltzmann method to provide benchmarks for the experiments. A stable discretized lattice Boltzmann equation is employed to simulate incompressible bubble-liquid flows with density ratio above 1000. Polynomial wall free energy boundary condition is introduced and examined for static cases with a bubble sitting on solid surfaces for a triple contact among bubble, liquid, and solid surface. In this work, we focus on the effects of channel ratio between with and without check valve on the dynamics of bubble-driven liquid circulation. This work is supported by NSF Collabrotive Research (1264739).

  6. Numerical Simulation of Capillary Channels Growth in Heterogeneous Porous Anode in Aluminum Electrolysis Cells by Lattice Boltzmann Method

    NASA Astrophysics Data System (ADS)

    Diop, Mouhamadou; Wang, Moran

    2014-11-01

    This paper presents results obtained from three-dimensional numerical simulations of multiphase reactive flows in porous anode block in aluminum cells controlling a great extent of mass, heat and chemical balance in the anode-cathode region. A lattice Boltzmann method based on thermal reactive multiphase flows, is developed to simulate the spatial and temporal distribution of fluids, the effects of gas rate and capillary instabilities in the cryolite. A new model, which involves eighteen lattice particles for the first and second derivative, is proposed to achieve accurate simulations at high fluid density ratio. The effects of the dissolution of gas and the capillary number on the flow field induced by gas bubbles evolution are investigated. It is found that capillary channels in the limit of small Stefan, the radial transport of reactant out of the capillary channel decay exponentially with the height of penetration in the porous anode. Several examples are solved by the proposed method to demonstrate the accuracy and robustness of the method.

  7. Exact vector channel sum rules at finite temperature and their applications to lattice QCD data analysis

    NASA Astrophysics Data System (ADS)

    Gubler, Philipp; Satow, Daisuke

    2016-11-01

    We derive three exact sum rules for the spectral function of the electromagnetic current with zero spatial momentum at finite temperature. Two of them are derived in this paper for the first time. We explicitly check that these sum rules are satisfied in the weak coupling regime and examine which sum rule is sensitive to the transport peak in the spectral function at low energy or the continuum at high energy. Possible applications of the three sum rules to lattice computations of the spectral function and transport coefficients are also discussed: we propose an Ansatz for the spectral function that can be applied to all three sum rules and fit it to available lattice data of the Euclidean vector correlator above the critical temperature. As a result, we obtain estimates for both the electrical conductivity σ and the second-order transport coefficient τJ .

  8. Retrieved Surface Emissivity Impact of New Cloud-Clearing Channel Set

    NASA Technical Reports Server (NTRS)

    Fishbein, Evan F.; Hook, Simon

    2006-01-01

    A viewgraph presentation on a proposed new cloud clearing channel set to improve land products and validate surface emissivity is given. The topics include: 1) Methodology; 2) Channel Selection; 3) Temperature Statistics; 4) 850 hPa Temperature Variability; 5) Status of Surface Retrieval; 6) Emissivity at 9 micrometers; 7) Emissivity Spectra; 8) Ha Megev (Israel); 9) Egypt One; 10) Salonga National Park, Zaire; 11) HaGolan (Israel/Syria); 12) Emissivity at 3.75 micrometers; 13) Improving Surface Retrieval; 14) Work Needed for V5 Delivery; 15) Effects of MODIS Emissivity; 16) Channel Selection; 17) 500 hPa Temperature Variability; 18) 850 hPa Temperature Variability; and 19) 850 hPa Temperature Differences;

  9. Simulation of forced convection in a channel with nanofluid by the lattice Boltzmann method

    PubMed Central

    2013-01-01

    This paper presents a numerical study of the thermal performance of fins mounted on the bottom wall of a horizontal channel and cooled with either pure water or an Al2O3-water nanofluid. The bottom wall of the channel is heated at a constant temperature and cooled by mixed convection of laminar flow at a relatively low temperature. The results of the numerical simulation indicate that the heat transfer rate of fins is significantly affected by the Reynolds number (Re) and the thermal conductivity of the fins. The influence of the solid volume fraction on the increase of heat transfer is more noticeable at higher values of the Re. PMID:23594696

  10. Simulation of forced convection in a channel with nanofluid by the lattice Boltzmann method.

    PubMed

    Sidik, Nor Azwadi Che; Khakbaz, Maysam; Jahanshaloo, Leila; Samion, Syahrullail; Darus, Amer Nordin

    2013-04-17

    This paper presents a numerical study of the thermal performance of fins mounted on the bottom wall of a horizontal channel and cooled with either pure water or an Al2O3-water nanofluid. The bottom wall of the channel is heated at a constant temperature and cooled by mixed convection of laminar flow at a relatively low temperature. The results of the numerical simulation indicate that the heat transfer rate of fins is significantly affected by the Reynolds number (Re) and the thermal conductivity of the fins. The influence of the solid volume fraction on the increase of heat transfer is more noticeable at higher values of the Re.

  11. CLASSICAL AREAS OF PHENOMENOLOGY: Lattice Boltzmann simulation of fluid flows in two-dimensional channel with complex geometries

    NASA Astrophysics Data System (ADS)

    Wen, Bing-Hai; Liu, Hai-Yan; Zhang, Chao-Ying; Wang, Qiang

    2009-10-01

    Boundary conditions (BCs) play an essential role in lattice Boltzmann (LB) simulations. This paper investigates several most commonly applied BCs by evaluating the relative L2-norm errors of the LB simulations for two-dimensional (2-D) Poiseuille flow. It is found that the relative L2-norm error resulting from FHML's BC is smaller than that from other BCs as a whole. Then, based on the FHML's BC, it formulates an LB model for simulating fluid flows in 2-D channel with complex geometries. Afterwards, the flows between two inclined plates, in a pulmonary blood vessel and in a blood vessel with local expansion region, are simulated. The numerical results are in good agreement with the analytical predictions and clearly show that the model is effective. It is expected that the model can be extended to simulate some real biologic flows, such as blood flows in arteries, vessels with stenosises, aneurysms and bifurcations, etc.

  12. Lattice Boltzmann simulation of flows in bifurcate channel at rotating inflow boundary conditions and resulted different outflow fluxes

    NASA Astrophysics Data System (ADS)

    Cai, Qing-Dong

    2011-08-01

    The Lattice Boltzmann method (LBM) is used to simulate the flow field in a bifurcate channel which is a simplified model of the draft tube of hydraulic turbine machine. According to the simulation results, some qualitative conclusions can be deduced. The reason of uneven flux in different branches of draft tube is given. Not only the vortex rope itself, but also the attenuation of the rotation strength is important in bringing on the uneven flux. The later leads to adverse pressure gradient, and changes the velocity profile. If the outlet contains more than one exit, the one that contains the vortex rope will lose flux because of this adverse pressure gradient. Several possible methods can be used to minimize the adverse pressure gradient domain in order to improve the efficiency of turbine machine.

  13. Tunable polarization plasma channel undulator for narrow bandwidth photon emission

    DOE PAGES

    Rykovanov, S. G.; Wang, J. W.; Kharin, V. Yu.; ...

    2016-09-09

    The theory of a plasma undulator excited by a short intense laser pulse in a parabolic plasma channel is presented. The undulator fields are generated either by the laser pulse incident off-axis and/or under the angle with respect to the channel axis. Linear plasma theory is used to derive the wakefield structure. It is shown that the electrons injected into the plasma wakefields experience betatron motion and undulator oscillations. Optimal electron beam injection conditions are derived for minimizing the amplitude of the betatron motion, producing narrow-bandwidth undulator radiation. Polarization control is readily achieved by varying the laser pulse injection conditions.

  14. Tunable polarization plasma channel undulator for narrow bandwidth photon emission

    NASA Astrophysics Data System (ADS)

    Rykovanov, S. G.; Wang, J. W.; Kharin, V. Yu.; Lei, B.; Schroeder, C. B.; Geddes, C. G. R.; Esarey, E.; Leemans, W. P.

    2016-09-01

    The theory of a plasma undulator excited by a short intense laser pulse in a parabolic plasma channel is presented. The undulator fields are generated either by the laser pulse incident off-axis and/or under the angle with respect to the channel axis. Linear plasma theory is used to derive the wakefield structure. It is shown that the electrons injected into the plasma wakefields experience betatron motion and undulator oscillations. Optimal electron beam injection conditions are derived for minimizing the amplitude of the betatron motion, producing narrow-bandwidth undulator radiation. Polarization control is readily achieved by varying the laser pulse injection conditions.

  15. Micromechanisms of brittle fracture: Acoustic emissions and electron channeling analyses

    SciTech Connect

    Gerberich, W.W.

    1990-06-01

    The objectives of this work are to: (i) Evaluate the initial stages of cleavage nucleation in single and polycrystalline samples; (ii) Determine the controlling event(s) which lead(s) to unstable cleavage (is it an unstable cluster'' of microcracks or a crack-tip opening displacement criterion for an array of ligaments surrounding these microcracks ); (iii) Determine how the process zone, which depends upon microstructure and processing history, affects the controlling event(s); (iv) Use selected area channeling patterns (SACP's) to assist in an independent measure of the cleavage fracture stress of grains cleaved at or just outside the elastic-plastic boundary; also, use it to evaluate static and dynamic strain distributions; and (v) Evaluate the effects of dislocation shielding and overload using combined methods of computational mechanics with discretized dislocation arrays and direct observations of dislocations using channeling, etch pit and birefringence methods. Accomplishments are discussed. 15 refs., 3 figs.

  16. Harnessing Geometric Frustration to Form Band Gaps in Acoustic Channel Lattices

    NASA Astrophysics Data System (ADS)

    Wang, Pai; Zheng, Yue; Fernandes, Matheus C.; Sun, Yushen; Xu, Kai; Sun, Sijie; Kang, Sung Hoon; Tournat, Vincent; Bertoldi, Katia

    2017-02-01

    We demonstrate both numerically and experimentally that geometric frustration in two-dimensional periodic acoustic networks consisting of arrays of narrow air channels can be harnessed to form band gaps (ranges of frequency in which the waves cannot propagate in any direction through the system). While resonant standing wave modes and interferences are ubiquitous in all the analyzed network geometries, we show that they give rise to band gaps only in the geometrically frustrated ones (i.e., those comprising of triangles and pentagons). Our results not only reveal a new mechanism based on geometric frustration to suppress the propagation of pressure waves in specific frequency ranges but also open avenues for the design of a new generation of smart systems that control and manipulate sound and vibrations.

  17. Harnessing Geometric Frustration to Form Band Gaps in Acoustic Channel Lattices.

    PubMed

    Wang, Pai; Zheng, Yue; Fernandes, Matheus C; Sun, Yushen; Xu, Kai; Sun, Sijie; Kang, Sung Hoon; Tournat, Vincent; Bertoldi, Katia

    2017-02-24

    We demonstrate both numerically and experimentally that geometric frustration in two-dimensional periodic acoustic networks consisting of arrays of narrow air channels can be harnessed to form band gaps (ranges of frequency in which the waves cannot propagate in any direction through the system). While resonant standing wave modes and interferences are ubiquitous in all the analyzed network geometries, we show that they give rise to band gaps only in the geometrically frustrated ones (i.e., those comprising of triangles and pentagons). Our results not only reveal a new mechanism based on geometric frustration to suppress the propagation of pressure waves in specific frequency ranges but also open avenues for the design of a new generation of smart systems that control and manipulate sound and vibrations.

  18. Surface growth for molten silicon infiltration into carbon millimeter-sized channels: Lattice-Boltzmann simulations, experiments and models

    NASA Astrophysics Data System (ADS)

    Sergi, Danilo; Camarano, Antonio; Molina, José Miguel; Ortona, Alberto; Narciso, Javier

    2016-01-01

    The process of liquid silicon (Si) infiltration is investigated for channels with radii from 0.25[mm] to 0.75[mm] drilled in compact carbon (C) preforms. The advantage of this setup is that the study of the phenomenon results can be simplified. For comparison purposes, attempts are made in order to work out a framework for evaluating the accuracy of simulations. The approach relies on dimensionless numbers involving the properties of the surface reaction. It turns out that complex hydrodynamic behavior derived from second Newton law can be made consistent with Lattice-Boltzmann (LB) simulations. The experiments give clear evidence that the growth of silicon carbide (SiC) proceeds in two different stages and basic mechanisms are highlighted. LB simulations prove to be an effective tool for the description of the growing phase. Namely, essential experimental constraints can be implemented. As a result, the existing models are useful to gain more insight on the process of reactive infiltration into porous media in the first stage of penetration, i.e. up to pore closure because of surface growth. A way allowing one to implement the resistance from chemical reaction in Darcy law is also proposed.

  19. Measurement and Analysis of Void Fraction in a Multiple-Channel Simplifying Triangle Tight Lattice Rod Bundle

    SciTech Connect

    Michio Sadatomi; Akimaro Kawahara; Hiroyuki Kudo; Hiroshi Shirai

    2006-07-01

    In order to know the effects of reduced surface tension on void fraction, adiabatic experiments were conducted for both air-water and air-water with surfactant systems at room temperature and pressure. Void fraction data were obtained for bubbly, slug, churn and annular flows in a vertical channel with two subchannels simplifying a triangle tight lattice rod bundle. The void fraction was found to be lower in air-water system than air-water with surfactant one. In addition, the void fractions for both systems were found to be lower than those calculated by various correlations in literatures for circular pipe flow. In order to study the cause of the above data trend, for annular flows as a first step, the void fraction has been calculated by a subchannel analysis using wall and interfacial friction correlations in literatures as constitutive equations, and by assuming the liquid film to be uniform over the wall perimeter. The best agreement between the calculation and the experiment has been obtained when NASCA correlation for wall friction force and modified RELAP5/MOD2 correlation incorporating reduced surface tension effects for interfacial friction force were used. (authors)

  20. Emission and gain characteristics of Er-doped multicomponent bismuthate channel waveguide

    NASA Astrophysics Data System (ADS)

    Kondo, Yuki; Ono, Motoshi; Reyes, Manuel; Hayashi, Hideaki; Kageyama, Junichi; Sugimoto, Naoki

    2005-04-01

    This paper reports on the preparation and the characteristics of Er-doped muliticomponent bismuthate channel waveguide. Dependence of emission lifetime of Er3+ ions on concentration of Er3+ ions is investigated. The concentration of Er3+ in the core film where concentration quenching effect starts is one order of magnitude higher than that of silicate materials. We show that the lower the hydroxyl ion content is, the longer the emission lifetime becomes and the emission lifetime of dehydrated core is the same as that of the fiber perform, namely the same quantum efficiency. The loss of the fabricated channel waveguide measured by cut-back method is 0.15 dB/cm at 1310 nm. Net gain of 8 dB is obtained at 1530 nm by using a 6-cm long waveguide pumped at 980 nm.

  1. A 31-channel MR brain array coil compatible with positron emission tomography.

    PubMed

    Sander, Christin Y; Keil, Boris; Chonde, Daniel B; Rosen, Bruce R; Catana, Ciprian; Wald, Lawrence L

    2015-06-01

    Simultaneous acquisition of MR and positron emission tomography (PET) images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (signal to noise ratio [SNR], g-factor) and PET attenuation. The coil design showed an improvement in attenuation by 190% (average) compared with conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical region of interest) compared with a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. © 2014 Wiley Periodicals, Inc.

  2. Comparative study of the discrete velocity and lattice Boltzmann methods for rarefied gas flows through irregular channels

    NASA Astrophysics Data System (ADS)

    Su, Wei; Lindsay, Scott; Liu, Haihu; Wu, Lei

    2017-08-01

    Rooted from the gas kinetics, the lattice Boltzmann method (LBM) is a powerful tool in modeling hydrodynamics. In the past decade, it has been extended to simulate rarefied gas flows beyond the Navier-Stokes level, either by using the high-order Gauss-Hermite quadrature, or by introducing the relaxation time that is a function of the gas-wall distance. While the former method, with a limited number of discrete velocities (e.g., D2Q36), is accurate up to the early transition flow regime, the latter method (especially the multiple relaxation time (MRT) LBM), with the same discrete velocities as those used in simulating hydrodynamics (i.e., D2Q9), is accurate up to the free-molecular flow regime in the planar Poiseuille flow. This is quite astonishing in the sense that less discrete velocities are more accurate. In this paper, by solving the Bhatnagar-Gross-Krook kinetic equation accurately via the discrete velocity method, we find that the high-order Gauss-Hermite quadrature cannot describe the large variation in the velocity distribution function when the rarefaction effect is strong, but the MRT-LBM can capture the flow velocity well because it is equivalent to solving the Navier-Stokes equations with an effective shear viscosity. Since the MRT-LBM has only been validated in simple channel flows, and for complex geometries it is difficult to find the effective viscosity, it is necessary to assess its performance for the simulation of rarefied gas flows. Our numerical simulations based on the accurate discrete velocity method suggest that the accuracy of the MRT-LBM is reduced significantly in the simulation of rarefied gas flows through the rough surface and porous media. Our simulation results could serve as benchmarking cases for future development of the LBM for modeling and simulation of rarefied gas flows in complex geometries.

  3. Comparative study of the discrete velocity and lattice Boltzmann methods for rarefied gas flows through irregular channels.

    PubMed

    Su, Wei; Lindsay, Scott; Liu, Haihu; Wu, Lei

    2017-08-01

    Rooted from the gas kinetics, the lattice Boltzmann method (LBM) is a powerful tool in modeling hydrodynamics. In the past decade, it has been extended to simulate rarefied gas flows beyond the Navier-Stokes level, either by using the high-order Gauss-Hermite quadrature, or by introducing the relaxation time that is a function of the gas-wall distance. While the former method, with a limited number of discrete velocities (e.g., D2Q36), is accurate up to the early transition flow regime, the latter method (especially the multiple relaxation time (MRT) LBM), with the same discrete velocities as those used in simulating hydrodynamics (i.e., D2Q9), is accurate up to the free-molecular flow regime in the planar Poiseuille flow. This is quite astonishing in the sense that less discrete velocities are more accurate. In this paper, by solving the Bhatnagar-Gross-Krook kinetic equation accurately via the discrete velocity method, we find that the high-order Gauss-Hermite quadrature cannot describe the large variation in the velocity distribution function when the rarefaction effect is strong, but the MRT-LBM can capture the flow velocity well because it is equivalent to solving the Navier-Stokes equations with an effective shear viscosity. Since the MRT-LBM has only been validated in simple channel flows, and for complex geometries it is difficult to find the effective viscosity, it is necessary to assess its performance for the simulation of rarefied gas flows. Our numerical simulations based on the accurate discrete velocity method suggest that the accuracy of the MRT-LBM is reduced significantly in the simulation of rarefied gas flows through the rough surface and porous media. Our simulation results could serve as benchmarking cases for future development of the LBM for modeling and simulation of rarefied gas flows in complex geometries.

  4. A 16-channel heterodyne electron cyclotron emission radiometer on J-TEXT.

    PubMed

    Yang, Z J; Phillips, P E; Zhuang, G; Xiao, J S; Huang, H; Rowan, W L; Wang, Z J

    2012-10-01

    To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field side. The ECE radiometer detects second-harmonic extraordinary mode in the frequency band of 94-125 GHz which corresponds to resonances from 1.8 T to 2.2 T. This ECE system consists of an ECE transmission line, a radio frequency unit, and two 8-channel intermediate frequency units. An in situ blackbody calibration source is applied for system calibration by comparison of hot and cold sources in order to provide an absolute temperature measurement.

  5. A 16-channel heterodyne electron cyclotron emission radiometer on J-TEXT

    SciTech Connect

    Yang, Z. J.; Zhuang, G.; Xiao, J. S.; Wang, Z. J.; Phillips, P. E.; Huang, H.; Rowan, W. L.

    2012-10-15

    To study equilibrium temporal dynamics and the mechanisms of magnetohydrodynamic instabilities, a 16-channel heterodyne electron cyclotron emission (ECE) radiometer has been developed to view the J-TEXT tokamak from the low field side. The ECE radiometer detects second-harmonic extraordinary mode in the frequency band of 94-125 GHz which corresponds to resonances from 1.8 T to 2.2 T. This ECE system consists of an ECE transmission line, a radio frequency unit, and two 8-channel intermediate frequency units. An in situ blackbody calibration source is applied for system calibration by comparison of hot and cold sources in order to provide an absolute temperature measurement.

  6. [Study on Square Super-Lattice Pattern with Surface Discharge in Dielectric Barrier Discharge by Optical Emission Spectra].

    PubMed

    Niu, Xue-jiao; Dong, Li-fang; Liu, Ying; Wang, Qian; Feng, Jian-yu

    2016-02-01

    Square super-lattice pattern with surface discharge consisting of central spots and dim spots is firstly observed in the mixture of argon and air by using a dielectric barrier discharge device with water electrodes. By observing the image, it is found that the central spot is located at the centriod of its surrounding four dim spots. The short-exposure image recorded by a high speed video camera shows that the dim spot results from the surface discharges (SDs). The brightness of the central spot and is quite different from that of the dim spot, which indicates that the plasma states of the central spot and the dim spot may be differentiated. The optical emission spectrum method is used to further study the several plasma parameters of the central spot and the dim spot in different argon content. The emission spectra of the N₂ second positive band (C³IIu --> B³ IIg) are measured, from which the molecule vibration temperatures of the central spot and the dim spot are calculated respectively. The broadening of spectral line 696.57 nm (2P₂-->1S₅) is used to study the electron densities of the central spot and the dim spot. It is found that the molecule vibration temperature and electron density of the dim spot are higher than those of the central spot in the same argon content The molecule vibration temperature and electron density of the central spot and the dim spot increase with the argon content increasing from 90% to 99.9%. The surface discharge induced by the volume discharge (VD) has the determinative effect on the formation of the dim spot The experimental results above play an important role in studying the formation mechanism of surface discharg&of square super-lattice pattern with surface discharge. In addition, the studies exert an influence on the application of surface discharge and volume discharge in different fields.

  7. Dual-channel spontaneous emission of quantum dots in magnetic metamaterials.

    PubMed

    Decker, Manuel; Staude, Isabelle; Shishkin, Ivan I; Samusev, Kirill B; Parkinson, Patrick; Sreenivasan, Varun K A; Minovich, Alexander; Miroshnichenko, Andrey E; Zvyagin, Andrei; Jagadish, Chennupati; Neshev, Dragomir N; Kivshar, Yuri S

    2013-01-01

    Metamaterials, artificial electromagnetic media realized by subwavelength nano-structuring, have become a paradigm for engineering electromagnetic space, allowing for independent control of both electric and magnetic responses of the material. Whereas most metamaterials studied so far are limited to passive structures, the need for active metamaterials is rapidly growing. However, the fundamental question on how the energy of emitters is distributed between both (electric and magnetic) interaction channels of the metamaterial still remains open. Here we study simultaneous spontaneous emission of quantum dots into both of these channels and define the control parameters for tailoring the quantum-dot coupling to metamaterials. By superimposing two orthogonal modes of equal strength at the wavelength of quantum-dot photoluminescence, we demonstrate a sharp difference in their interaction with the magnetic and electric metamaterial modes. Our observations reveal the importance of mode engineering for spontaneous emission control in metamaterials, paving a way towards loss-compensated metamaterials and metamaterial nanolasers.

  8. Dual-channel spontaneous emission of quantum dots in magnetic metamaterials

    NASA Astrophysics Data System (ADS)

    Decker, Manuel; Staude, Isabelle; Shishkin, Ivan I.; Samusev, Kirill B.; Parkinson, Patrick; Sreenivasan, Varun K. A.; Minovich, Alexander; Miroshnichenko, Andrey E.; Zvyagin, Andrei; Jagadish, Chennupati; Neshev, Dragomir N.; Kivshar, Yuri S.

    2013-12-01

    Metamaterials, artificial electromagnetic media realized by subwavelength nano-structuring, have become a paradigm for engineering electromagnetic space, allowing for independent control of both electric and magnetic responses of the material. Whereas most metamaterials studied so far are limited to passive structures, the need for active metamaterials is rapidly growing. However, the fundamental question on how the energy of emitters is distributed between both (electric and magnetic) interaction channels of the metamaterial still remains open. Here we study simultaneous spontaneous emission of quantum dots into both of these channels and define the control parameters for tailoring the quantum-dot coupling to metamaterials. By superimposing two orthogonal modes of equal strength at the wavelength of quantum-dot photoluminescence, we demonstrate a sharp difference in their interaction with the magnetic and electric metamaterial modes. Our observations reveal the importance of mode engineering for spontaneous emission control in metamaterials, paving a way towards loss-compensated metamaterials and metamaterial nanolasers.

  9. Calibration of a 32 channel electron cyclotron emission radiometer on the HL-2A tokamak

    SciTech Connect

    Shi, Z. B. Jiang, M.; Huang, X. L.; Zhong, W. L.; Chen, W.; Che, Y. L.; Liu, Z. T.; Ding, X. T.; Yang, Q. W.; Duan, X. R.

    2014-02-15

    A novel 32-channel electron cyclotron emission radiometer has been designed and tested for the measurement of electron temperature profiles on the HL-2A tokamak. This system is based on the intermediate frequency filter detection technique, and has the features of wide working frequency range and high spatial resolution. Two relative calibration methods have been investigated: sweeping the toroidal magnetic field and hopping the output frequency of the local oscillator. Preliminary results show that both methods can ensure reasonable profiles.

  10. An upgraded 32-channel heterodyne electron cyclotron emission radiometer on Tore Supra

    SciTech Connect

    Segui, J.L.; Molina, D.; Giruzzi, G.; Goniche, M.; Huysmans, G.; Maget, P.; Ottaviani, M.

    2005-12-15

    A 32-channel, 1 GHz spaced heterodyne radiometer is used on the Tore Supra tokamak to measure electron cyclotron emission (ECE) in the frequency range 78-110 GHz for the ordinary mode (O:E parallel B,k perpendicular B) and 94-126 GHz for the extraordinary mode (X:E perpendicular B,k perpendicular B). The radial resolution is essentially limited by ECE relativistic effects, depending on electron temperature and density, and not by the channels' frequency spacing. The time resolution depends on the acquisition scheme: the system allows for both 1 ms and 10 {mu}s acquisition. For example, this leads to precise electron temperature mapping during MHD activity. First experimental results obtained with this upgraded 32-channel radiometer are presented.

  11. White light emission from Eu3+ in CaIn2O4 host lattices

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoming; Lin, Cuikun; Lin, Jun

    2007-02-01

    CaIn2O4:xEu3+ (x =0.5%,1.0%,1.5%) phosphors were prepared by the Pechini sol-gel process [U.S. Patent No. 3,330,697 (1967)] and characterized by x-ray diffraction and photoluminescence and cathodoluminescence spectra as well as lifetimes. Under the excitation of 397nm ultraviolet light and low voltage electron beams, these phosphors show the emission lines of Eu3+ corresponding to D0,1,2,35-FJ7 (J=0,1,2,3,4) transitions from 400to700nm (whole visible spectral region) with comparable intensity, resulting in a white light emission with a quantum efficiency near 10%. The luminescence mechanism for Eu3+ in CaIn2O4 has been elucidated.

  12. Modified emission of extended light emitting layers by selective coupling to collective lattice resonances

    NASA Astrophysics Data System (ADS)

    Ramezani, Mohammad; Lozano, Gabriel; Verschuuren, Marc A.; Gómez-Rivas, Jaime

    2016-09-01

    We demonstrate that the coupling between light emitters in extended polymer layers and modes supported by arrays of plasmonic particles can be selectively enhanced by accurate positioning of the emitters in regions where the electric field intensity of a given mode is maximized. The enhancement, which we measure to reach up to 70%, is due to the improved spatial overlap and coupling between the optical mode and emitters. This improvement of the coupling leads to a modification of the emission spectrum and the luminous efficacy of the sample.

  13. [Study on spectral characteristics of third-order harmonic emission of plasma channels in atmosphere].

    PubMed

    Li, Hai-ning; Zhang, Li-ping; Wu, Hong; Li, Xian; Ding, Liang-en

    2008-06-01

    The authors observed the spectrum of third-order harmonic (TH) emission of the plasma channel in atmosphere by focused ultra-short laser pulses under various conditions. The authors used pulsed Ti: sapphire chirped pulse amplification (CPA) femtosecond laser system, with the central wavelength at 795 nm, repetition rate of 10 Hz, pulse duration of 30 fs and the pulse energy of 12 mJ, focused by a concave mirror with the focal length of 0.5 m, which can generate about 10(13) W x cm(-2) of power intensity. Under this condition, the dynamic balance between nonlinear Kerr self-focusing and plasma defocusing can support a long plasma channel in the interaction of the high intense laser pulses and gaseous media, and the interaction length between the laser pulse and air is greatly elongated, which is helpful to generating third-order harmonic emission. The full width at half maximum (FWHM) of the generated third-order harmonic spectrum is 15 nm with the central wavelength at 265 nm in the forward direction. The spectra of third-order harmonic emission red shift when the laser pulse is positive chirped. On the contrary, the spectra of third-order harmonic emission blue shift when the laser pulse is negative chirped. Proper dispersion can increase the intensity of third-order harmonic spectrum peak and sharped the spectrum peak. With the group velocity dispersion (GVD) of the pulses equal to +1.3 x 10(5) fs2, the peak of third-order harmonic spectrum red shifts and the group velocity dispersion of laser pulses equals to zero fs2. The experiment shows that the rising wing of pulses can obtain higher third-order harmonic conversion efficiency than the falling edge of the pulses. In addition, acoustic-optic programmable dispersive filter (AOPDF) in the laser system can control the spectrum shape of the laser. Changing the hole position of acoustic-optic programmable dispersive filter can also shift the spectrum shape of third-order harmonic emission in a certain range

  14. Two-channel rocket photometer for tracing weak optical emissions at night

    NASA Astrophysics Data System (ADS)

    Gogoshev, M. M.; Petkov, N. P.; Stavrakov, T. L.; Kunev, K. D.; Kostadinov, I. N.

    The photometer was developed to determine the vertical profiles of optical emissions in the F-region and to juxtapose them with optical measurements made on board the Intercosmos-Bulgaria-1300 satellite by means of the EMO-5 spectral and spatial scanning photometric system. The photometer contains two optical channels comprising the input blinds, the lenses, and the interference filters. The light signal, measured in intensity, is converted into an electrical signal by means of photoconvertors based on a photomultiplier. The protective blind contains 10 diaphragms, so fabricated and positioned as to lower to the maximum extent the level of the side hum signal entering the apparatus of the optical channel, whose complete visual angle is 15 deg.

  15. A novel method to form conducting channels in SiOx(Si ) films for field emission application

    NASA Astrophysics Data System (ADS)

    Semenenko, M.; Evtukh, A.; Yilmazoglu, O.; Hartnagel, H. L.; Pavlidis, D.

    2010-01-01

    The electrical and field emission properties of SiOx(Si ) films are studied. SiOx(Si ) films of 40-100nm thick are obtained by plasma-enhanced chemical vapor deposition and thermal evaporation of Si powder onto Si substrates. Nanosized electrical conducting channels are formed in SiOx(Si ) films by electrical conditioning at high current densities. The structures with conducting channels demonstrate increased field emission current and decreased threshold voltage compared to as-deposited SiOx(Si ) films. The decrease in threshold voltage for electron field emission is explained by local enhancement of electric field. The diameters of conducting channels are estimated from the effective emission area to be in the range of 1-2nm.

  16. Channels

    NASA Image and Video Library

    2014-04-29

    Two channels are visible in this image from NASA 2001 Mars Odyssey spacecraft . The smaller one near the bottom did not carve as deeply as the larger channel at the top. The channel near the top of the image is near the origin of Mamers Valles.

  17. Effect of open channel filter on particle emissions of modern diesel engine.

    PubMed

    Heikkilä, Juha; Rönkkö, Topi; Lähde, Tero; Lemmetty, Mikko; Arffman, Anssi; Virtanen, Annele; Keskinen, Jorma; Pirjola, Liisa; Rothe, Dieter

    2009-10-01

    Particle emissions of modern diesel engines are of a particular interest because of their negative health effects. The special interest is in nanosized solid particles. The effect of an open channel filter on particle emissions of a modern heavy-duty diesel engine (MAN D2066 LF31, model year 2006) was studied. Here, the authors show that the open channel filter made from metal screen efficiently reduced the number of the smallest particles and, notably, the number and mass concentration of soot particles. The filter used in this study reached 78% particle mass reduction over the European Steady Cycle. Considering the size-segregated number concentration reduction, the collection efficiency was over 95% for particles smaller than 10 nm. The diffusion is the dominant collection mechanism in small particle sizes, thus the collection efficiency decreased as particle size increased, attaining 50% at 100 nm. The overall particle number reduction was 66-99%, and for accumulation-mode particles the number concentration reduction was 62-69%, both depending on the engine load.

  18. Attribution of atmospheric sulfur dioxide over the English Channel to dimethyl sulfide and changing ship emissions

    NASA Astrophysics Data System (ADS)

    Yang, Mingxi; Bell, Thomas G.; Hopkins, Frances E.; Smyth, Timothy J.

    2016-04-01

    Atmospheric sulfur dioxide (SO2) was measured continuously from the Penlee Point Atmospheric Observatory (PPAO) near Plymouth, United Kingdom, between May 2014 and November 2015. This coastal site is exposed to marine air across a wide wind sector. The predominant southwesterly winds carry relatively clean background Atlantic air. In contrast, air from the southeast is heavily influenced by exhaust plumes from ships in the English Channel as well as near Plymouth Sound. A new International Maritime Organization (IMO) regulation came into force in January 2015 to reduce the maximum allowed sulfur content in ships' fuel 10-fold in sulfur emission control areas such as the English Channel. Our observations suggest a 3-fold reduction in ship-emitted SO2 from 2014 to 2015. Apparent fuel sulfur content calculated from coincidental SO2 and carbon dioxide (CO2) peaks from local ship plumes show a high level of compliance to the IMO regulation (> 95 %) in both years (˜ 70 % of ships in 2014 were already emitting at levels below the 2015 cap). Dimethyl sulfide (DMS) is an important source of atmospheric SO2 even in this semi-polluted region. The relative contribution of DMS oxidation to the SO2 burden over the English Channel increased from about one-third in 2014 to about one-half in 2015 due to the reduction in ship sulfur emissions. Our diel analysis suggests that SO2 is removed from the marine atmospheric boundary layer in about half a day, with dry deposition to the ocean accounting for a quarter of the total loss.

  19. Gravitational wave emission from the single-degenerate channel of Type Ia supernovae.

    PubMed

    Falta, David; Fisher, Robert; Khanna, Gaurav

    2011-05-20

    The thermonuclear explosion of a C/O white dwarf as a Type Ia supernova (SN Ia) generates a kinetic energy comparable to that released by a massive star during a SN II event. Current observations and theoretical models have established that SNe Ia are asymmetric, and therefore--like SNe II--potential sources of gravitational wave (GW) radiation. We perform the first detailed calculations of the GW emission for a SN Ia of any type within the single-degenerate channel. The gravitationally confined detonation (GCD) mechanism predicts a strongly polarized GW burst in the frequency band around 1 Hz. Third-generation spaceborne GW observatories currently in planning may be able to detect this predicted signal from SNe Ia at distances up to 1 Mpc. If observable, GWs may offer a direct probe into the first few seconds of the SNe Ia detonation.

  20. Channeling, Volume Reection and Gamma Emission Using 14GeV Electrons in Bent Silicon Crystals

    SciTech Connect

    Benson, Brandon

    2015-08-14

    High energy electrons can be deflected with very tight bending radius using a bent silicon crystal. This produces gamma radiation. As these crystals can be thin, a series of bent silicon crystals with alternating direction has the potential to produce coherent gamma radiation with reasonable energy of the driving electron beam. Such an electron crystal undulator offers the prospect for higher energy radiation at lower cost than current methods. Permanent magnetic undulators like LCLS at SLAC National Accelerator Laboratory are expensive and very large (about 100 m in case of the LCLS undulator). Silicon crystals are inexpensive and compact when compared to the large magnetic undulators. Additionally, such a high energy coherent light source could be used for probing through materials currently impenetrable by x-rays. In this work we present the experimental data and analysis of experiment T523 conducted at SLAC National Accelerator Laboratory. We collected the spectrum of gamma ray emission from 14 GeV electrons on a bent silicon crystal counting single photons. We also investigated the dynamics of electron motion in the crystal i.e. processes of channeling and volume reflection at 14 GeV, extending and building off previous work. Our single photon spectrum for the amorphous crystal orientation is consistent with bremsstrahlung radiation and the volume reflection crystal orientation shows a trend consistent with synchrotron radiation at a critical energy of 740 MeV. We observe that in these two cases the data are consistent, but we make no further claims because of statistical limitations. We also extended the known energy range of electron crystal dechanneling length and channeling efficiency to 14 GeV.

  1. Channels

    NASA Image and Video Library

    2015-11-20

    Today's VIS image shows a number of unnamed channels located on the northeastern margin of Terra Sabaea. Orbit Number: 61049 Latitude: 33.5036 Longitude: 58.6967 Instrument: VIS Captured: 2015-09-18 12:54 http://photojournal.jpl.nasa.gov/catalog/PIA20097

  2. Twenty-channel grating polychromator diagnostic system for electron cyclotron emission measurement in JT-60

    NASA Astrophysics Data System (ADS)

    Ishida, S.; Nagashima, A.; Sato, M.; Isei, N.; Matoba, T.

    1990-10-01

    A twenty-channel grating polychromator diagnostic system has been built to measure the temporal evolution of local electron temperatures in JT-60. A cross Czerny-Turner diffraction grating spectrometer is utilized for the measurement of second-harmonic electron cyclotron emission with extraordinary modes in the range 85-300 GHz, in which a grating plate grooved on both faces with different grating periods is applied effectively to yield a wide coverage for the toroidal fields. The grating angle is automatically set up by control of a stepping motor according to the relation of the grating equation. The diffracted light is detected by 20 indium-antimonide hot-electron bolometers cooled at 4.3 K in a modified Solvay cycle cryogenic refrigerator. A typical resolving power of the instrument was measured to be λ/Δλ˜130, providing a spatial resolution of 2.3 cm at the plasma center. The transmission line over ˜38 m long is composed of oversized S-band waveguides. The total transmissivity of this system is estimated to be ˜0.01.

  3. Emission of photons by positrons channeled in single crystals near an energy of 100 GeV

    SciTech Connect

    Maisheev, V. A.; Chesnokov, Yu. A. Chirkov, P. N.; Yazynin, I. A.; Bolognini, D.; Hasan, S.; Prest, M.; Vallazza, E.

    2016-05-15

    Emission by 120-GeV positrons in the channeling regime in the (011) plane of a silicon single crystal has been considered. Trajectories of positrons under different initial conditions have been calculated within the theory of nonlinear oscillations. The amplitude distribution function of channeled particles has been determined taking into account the nonlinearity of their motion. The intensity of radiation under various initial conditions has been calculated by two different methods. These results can be useful for comparison with experimental data at energies of positrons beginning with 100 GeV and higher.

  4. Channelling experiments on the lattice location of hydrogen in metals using the nuclear reaction 1H(11B, α)αα

    NASA Astrophysics Data System (ADS)

    Yagi, Eiichi

    1992-03-01

    In order to locate hydrogen dissolved in metals a nuclear reaction 1H(11B, α)αα was applied to a channelling method. As an example of this application the results of the following two experiments were briefly reported. (1) The lattice location of H in V was investigated under a <001> compressive stress of 7 kg/mm2 below the elastic limit. The configuration of hydrogen is extremely sensitive to compressive stress and changes from a tetrahedral (T) site to a diplaced-T or 4T configuration. On release of this stress the hydrogen atoms returned to T-sites. (2) To elucidate the mechanism of the enhancement of the terminal solubility for hydrogen (TSH) in Nb on alloying with undersized Mo atoms, the state of hydrogen was studied in Nb-based Nb-Mo dilute alloys. It was demonstrated that H atoms are trapped by Mo atoms and located at sites displaced from T-sites by about 0.6 Å. This result supports the trapping model for the enhancement of the TSH in the region of low Mo concentration.

  5. A Multi-Channel Method for Retrieving Surface Temperature for High-Emissivity Surfaces from Hyperspectral Thermal Infrared Images.

    PubMed

    Zhong, Xinke; Labed, Jelila; Zhou, Guoqing; Shao, Kun; Li, Zhao-Liang

    2015-06-08

    The surface temperature (ST) of high-emissivity surfaces is an important parameter in climate systems. The empirical methods for retrieving ST for high-emissivity surfaces from hyperspectral thermal infrared (HypTIR) images require spectrally continuous channel data. This paper aims to develop a multi-channel method for retrieving ST for high-emissivity surfaces from space-borne HypTIR data. With an assumption of land surface emissivity (LSE) of 1, ST is proposed as a function of 10 brightness temperatures measured at the top of atmosphere by a radiometer having a spectral interval of 800-1200 cm(-1) and a spectral sampling frequency of 0.25 cm(-1). We have analyzed the sensitivity of the proposed method to spectral sampling frequency and instrumental noise, and evaluated the proposed method using satellite data. The results indicated that the parameters in the developed function are dependent on the spectral sampling frequency and that ST of high-emissivity surfaces can be accurately retrieved by the proposed method if appropriate values are used for each spectral sampling frequency. The results also showed that the accuracy of the retrieved ST is of the order of magnitude of the instrumental noise and that the root mean square error (RMSE) of the ST retrieved from satellite data is 0.43 K in comparison with the AVHRR SST product.

  6. A Multi-Channel Method for Retrieving Surface Temperature for High-Emissivity Surfaces from Hyperspectral Thermal Infrared Images

    PubMed Central

    Zhong, Xinke; Labed, Jelila; Zhou, Guoqing; Shao, Kun; Li, Zhao-Liang

    2015-01-01

    The surface temperature (ST) of high-emissivity surfaces is an important parameter in climate systems. The empirical methods for retrieving ST for high-emissivity surfaces from hyperspectral thermal infrared (HypTIR) images require spectrally continuous channel data. This paper aims to develop a multi-channel method for retrieving ST for high-emissivity surfaces from space-borne HypTIR data. With an assumption of land surface emissivity (LSE) of 1, ST is proposed as a function of 10 brightness temperatures measured at the top of atmosphere by a radiometer having a spectral interval of 800–1200 cm−1 and a spectral sampling frequency of 0.25 cm−1. We have analyzed the sensitivity of the proposed method to spectral sampling frequency and instrumental noise, and evaluated the proposed method using satellite data. The results indicated that the parameters in the developed function are dependent on the spectral sampling frequency and that ST of high-emissivity surfaces can be accurately retrieved by the proposed method if appropriate values are used for each spectral sampling frequency. The results also showed that the accuracy of the retrieved ST is of the order of magnitude of the instrumental noise and that the root mean square error (RMSE) of the ST retrieved from satellite data is 0.43 K in comparison with the AVHRR SST product. PMID:26061199

  7. Hadronic Interactions from Lattice QCD

    SciTech Connect

    Konstantinos Orginos

    2006-03-19

    In this talk I discuss a few recent results on lattice calculations of scattering lengths in hadronic processes. In particular, I present the scattering length of the pion-pion scattering in the I=2 channel and the nucleon-nucleon {sup 1}S{sub 0} channel and {sup 3}S{sub 1}-{sup 3}D{sub 1} coupled channels.

  8. Simulation of field-induced molecular dissociation in atom-probe tomography: Identification of a neutral emission channel

    NASA Astrophysics Data System (ADS)

    Zanuttini, David; Blum, Ivan; Rigutti, Lorenzo; Vurpillot, François; Douady, Julie; Jacquet, Emmanuelle; Anglade, Pierre-Matthieu; Gervais, Benoit

    2017-06-01

    We investigate the dynamics of dicationic metal-oxide molecules under large electric-field conditions, on the basis of ab initio calculations coupled to molecular dynamics. Applied to the case of ZnO2 + in the field of atom probe tomography (APT), our simulation reveals the dissociation into three distinct exit channels. The proportions of these channels depend critically on the field strength and on the initial molecular orientation with respect to the field. For typical field strength used in APT experiments, an efficient dissociation channel leads to emission of neutral oxygen atoms, which escape detection. The calculated composition biases and their dependence on the field strength show remarkable consistency with recent APT experiments on ZnO crystals. Our work shows that bond breaking in strong static fields may lead to significant neutral atom production, and therefore to severe elemental composition biases in measurements.

  9. Soliton assisted control of source to drain electron transport along natural channels - crystallographic axes - in two-dimensional triangular crystal lattices

    NASA Astrophysics Data System (ADS)

    Chetverikov, A. P.; Ebeling, W.; Velarde, M. G.

    2016-09-01

    We present computational evidence of the possibility of fast, supersonic or subsonic, nearly loss-free ballistic-like transport of electrons bound to lattice solitons (a form of electron surfing on acoustic waves) along crystallographic axes in two-dimensional anharmonic crystal lattices. First we study the structural changes a soliton creates in the lattice and the time lapse of recovery of the lattice. Then we study the behavior of one electron in the polarization field of one and two solitons with crossing pathways with suitably monitored delay. We show how an electron surfing on a lattice soliton may switch to surf on the second soliton and hence changing accordingly the direction of its path. Finally we discuss the possibility to control the way an excess electron proceeds from a source at a border of the lattice to a selected drain at another border by following appropriate straight pathways on crystallographic axes.

  10. Parity mix interferences and pairwise channel cancellation in the attosecond control of electron emission from {{\\rm{H}}}_{2}^{+}

    NASA Astrophysics Data System (ADS)

    Boll, D. I. R.; Fojón, O. A.

    2017-03-01

    We study the single photoionization of simple diatomic molecules such as {{{H}}}2+ by a train of attopulses assisted by a near infrared laser. In particular, we focus on the so called orbital parity mix interferences leading to asymmetrical electron emission. We employ a non-perturbative model obtaining for those asymmetries analytical expressions with a functional form independent of the target structure encoding the interaction of the photoelectron with the laser field to all orders. Related to these interferences, we give conditions at which a pairwise cancellation of channels opened by the laser field occurs. Finally, we exploit the non-perturbative character of our model to analyze the dependence of the asymmetrical electron emission and the angular distribution of photoelectrons with the laser intensity. An asymmetric inhibition of the emission in the classical direction is found.

  11. Kalman filter physical retrieval of surface emissivity and temperature from SEVIRI infrared channels: a validation and inter-comparison study

    NASA Astrophysics Data System (ADS)

    Masiello, G.; Serio, C.; Venafra, S.; Liuzzi, G.; Göttsche, F.; Trigo, I. F.; Watts, P.

    2015-04-01

    A Kalman filter based approach for the physical retrieval of surface temperature and emissivity from SEVIRI (Spinning Enhanced Visible and Infrared Imager) infrared observations has been developed and validated against in situ and satellite observations. Validation for land has been provided based on in situ observations from the two permanent stations Evora and Gobabeb operated by Karlsruhe Institute of Technology (KIT) within the framework of EUMETSAT's Satellite Application Facility on Land Surface Analysis (LSA-SAF). Sea surface retrievals have been intercompared on a broad spatial scale with equivalent satellite products (MODIS or Moderate Resolution Imaging Spectroradiometer and AVHRR or Advanced Very High Resolution Radiometer) and ECMWF (European Centre for Medium Range Weather Forecasts) analyses. Results show that for surface temperature the algorithm yields an accuracy of ≈ ± 1.5 °C in case of land and ≈ ± 1.0 °C in case of sea surface. Comparisons with polar satellite instruments over the sea surface show nearly zero temperature bias. Over the land surface the retrieved emissivity follows the seasonal vegetation cycle and allows to identify desert sand regions because of strong reststrahlen bands of Quartz in the SEVIRI channel at 8.7 μm. Considering the two validation stations, we have that emissivity retrieved in SEVIRI channel 10.8 μm over the gravel plains of the Namib desert is in excellent agreement with in situ observations. Over Evora, the seasonal variation of emissivity with vegetation is successfully retrieved and yields emissivity values for green and dry vegetation that are in good agreement with spectral library data. The algorithm has been applied to the SEVIRI full disk and emissivity maps on that global scale have been physically retrieved for the first time.

  12. Kalman filter physical retrieval of surface emissivity and temperature from SEVIRI infrared channels: a validation and intercomparison study

    NASA Astrophysics Data System (ADS)

    Masiello, G.; Serio, C.; Venafra, S.; Liuzzi, G.; Göttsche, F.; Trigo, I. F.; Watts, P.

    2015-07-01

    A Kalman filter-based approach for the physical retrieval of surface temperature and emissivity from SEVIRI (Spinning Enhanced Visible and Infrared Imager) infrared observations has been developed and validated against in situ and satellite observations. Validation for land has been provided based on in situ observations from the two permanent stations at Evora and Gobabeb operated by Karlsruhe Institute of Technology (KIT) within the framework of EUMETSAT's Satellite Application Facility on Land Surface Analysis (LSA SAF). Sea surface retrievals have been intercompared on a broad spatial scale with equivalent satellite products (MODIS, Moderate Resolution Imaging Spectroradiometer, and AVHRR, Advanced Very High Resolution Radiometer) and ECMWF (European Centre for Medium-Range Weather Forecasts) analyses. For surface temperature, the Kalman filter yields a root mean square accuracy of ≍ ±1.5 °C for the two land sites considered and ≍ ±1.0 °C for the sea. Comparisons with polar satellite instruments over the sea surface show nearly zero temperature bias. Over the land surface the retrieved emissivity follows the seasonal vegetation cycle and permits identification of desert sand regions using the SEVIRI channel at 8.7 μm due to the strong quartz reststrahlen bands around 8-9 μm. Considering the two validation stations, we have found that emissivity retrieved in SEVIRI channel 10.8 μm over the gravel plains of the Namibian desert is in excellent agreement with in situ observations. Over Evora, the seasonal variation of emissivity with vegetation is successfully retrieved and yields emissivity values for green and dry vegetation that are in good agreement with spectral library data. The algorithm has been applied to the SEVIRI full disk, and emissivity maps on that global scale have been physically retrieved for the first time.

  13. Generalizing Word Lattice Translation

    DTIC Science & Technology

    2008-02-01

    demonstrate substantial gains for Chinese -English and Arabic -English translation. Keywords: word lattice translation, phrase-based and hierarchical...introduce in reordering models. Our experiments evaluating the approach demonstrate substantial gains for Chinese -English and Arabic -English translation. 15...Section 4 presents two applications of the noisier channel paradigm, demonstrating substantial performance gains in Arabic -English and Chinese -English

  14. A 31-Channel MR Brain Array Coil Compatible with Positron Emission Tomography

    PubMed Central

    Sander, Christin Y.; Keil, Boris; Chonde, Daniel B.; Rosen, Bruce R.; Catana, Ciprian; Wald, Lawrence L.

    2014-01-01

    Purpose Simultaneous acquisition of MR and PET images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. Methods A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (SNR, g-factor) and PET attenuation. Results The coil design showed an improvement in attenuation by 190% (average) compared to conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical ROI) compared to a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. Conclusion The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. PMID:25046699

  15. Simultaneous measurement of temperature and emissivity of lunar regolith simulant using dual-channel millimeter-wave radiometry.

    PubMed

    McCloy, J S; Sundaram, S K; Matyas, J; Woskov, P P

    2011-05-01

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments). The state-of-the-art dual channel MMW passive radiometer with active interferometric capabilities at 137 GHz described here allows for radiometric measurements of sample temperature and emissivity up to at least 1600 °C with simultaneous measurement of sample surface dynamics. These capabilities have been used to demonstrate dynamic measurement of melting of powders of simulated lunar regolith and static measurement of emissivity of solid samples. The paper presents the theoretical background and basis for the dual-receiver system, describes the hardware in detail, and demonstrates the data analysis. Post-experiment analysis of emissivity versus temperature allows further extraction from the radiometric data of millimeter wave viewing beam coupling factors, which provide corroboratory evidence to the interferometric data of the process dynamics observed. These results show the promise of the MMW system for extracting quantitative and qualitative process parameters for industrial processes and access to real-time dynamics of materials behavior in extreme environments.

  16. Simultaneous measurement of temperature and emissivity of lunar regolith simulant using dual-channel millimeter-wave radiometry

    SciTech Connect

    McCloy, J. S.; Sundaram, S. K.; Matyas, J.; Woskov, P. P.

    2011-01-01

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments). The state-of-the-art dual channel MMW passive radiometer with active interferometric capabilities at 137 GHz described here allows for radiometric measurements of sample temperature and emissivity up to at least 1600 °C with simultaneous measurement of sample surface dynamics. These capabilities have been used to demonstrate dynamic measurement of melting of powders of simulated lunar regolith and static measurement of emissivity of solid samples. The paper presents the theoretical background and basis for the dual-receiver system, describes the hardware in detail, and demonstrates the data analysis. Post-experiment analysis of emissivity versus temperature allows further extraction from the radiometric data of millimeter wave viewing beam coupling factors, which provide corroboratory evidence to the interferometric data of the process dynamics observed. Finally, these results show the promise of the MMW system for extracting quantitative and qualitative process parameters for industrial processes and access to real-time dynamics of materials behavior in extreme environments.

  17. Development of 40 channel waveform sampling CMOS ASIC board for Positron Emission Tomography

    NASA Astrophysics Data System (ADS)

    Shimazoe, Kenji; Yeol, Yeom-Jung; Minamikawa, Yasuhiro; Tomida, Yuki; Takahashi, Hiroyuki; Fujita, Kaoru; Nakazawa, Masaharu; Murayama, Hideo

    2007-04-01

    We have designed and fabricated 10 channel/6-bit waveform sampling ASICs using ROHM 0.35 μm CMOS technology. This chip was designed for GSO-APD γ-ray detector and provides a function of "waveform recording" at a sampling frequency of 100 MHz. This chip has 10 channel inputs and each channel has preamp/variable gain amplifier/6-bit folding ADC. The folding ADC greatly reduces the number of comparators and the power consumption of the chip. This chip provides a full function of recording a transient behavior of detector charge signals for each pulse. Self-trigger function is equipped with the system and this will enable simultaneous record of all input waveforms. Each channel has 64 words FIFO where each waveform data are stored. Stored data are converted to serial data and passed to an FPGA where we can implement a detailed signal processing. This chip is operated at 3.3 V and the power consumption is 1.2 W/chip. We have developed a data acquisition board using four bare chips. This board has 40 input channels and we plan to use this board for APD-based DOI-PET detector system which utilizes several different crystals to recognize depth positions by the difference in their decay times.

  18. [Study on Hexagonal Super-Lattice Pattern with Light Spot and Dim Spot in Dielectric Barrier Discharge by Optical Emission Spectra].

    PubMed

    Liu, Ying; Dong, Li-fang; Niu, Xue-jiao; Zhang, Chao

    2016-02-01

    The hexagonal super-lattice pattern composed of the light spot and the dim spot is firstly observed and investigated in the discharge of gas mixture of air and argon by using the dielectric barrier discharge device with double water electrodes. It is found that the dim spot is located at the center of its surrounding three light spots by observing the discharge image. Obviously, the brightness of the light spot and the dim spot are different, which indicates that the plasma states of the light spot and the dim spot may be different. The optical emission spectrum method is used to further study the several plasma parameters of the light spot and the dim spot in different argon content. The emission spectra of the N₂ second positive band (C³IIu --> B³IIg) are measured, from which the molecule vibration temperatures of the light spot and the dim spot are calculated. Based on the relative intensity ratio of the line at 391.4 nm and the N₂ line at 394.1 nm, the average electron energies of the light spot and the dim spot are investigated. The broadening of spectral line 696.57 nm (2P₂-1S₅) is used to study the electron densities of the light spot and the dim spot. The experiment shows that the molecule vibration temperature, average electron energy and the electron density of the dim spot are higher than those of the light spot in the same argon content. The molecule vibration temperature and electron density of the light spot and dim spot increase with the argon content increasing from 70% to 95%, while average electron energies of the light spot and dim spot decrease gradually. The short-exposure image recorded by a high speed video camera shows that the dim spot results from the surface discharges (SDs). The surface discharge induced by the volume discharge (VD) has the decisive effect on the formation of the dim spot. The experiment above plays an important role in studying the formation mechanism of the hexagonal super-lattice pattern with light spot and

  19. Mesoscale analysis of failure in quasi-brittle materials: comparison between lattice model and acoustic emission data.

    PubMed

    Grégoire, David; Verdon, Laura; Lefort, Vincent; Grassl, Peter; Saliba, Jacqueline; Regoin, Jean-Pierre; Loukili, Ahmed; Pijaudier-Cabot, Gilles

    2015-10-25

    The purpose of this paper is to analyse the development and the evolution of the fracture process zone during fracture and damage in quasi-brittle materials. A model taking into account the material details at the mesoscale is used to describe the failure process at the scale of the heterogeneities. This model is used to compute histograms of the relative distances between damaged points. These numerical results are compared with experimental data, where the damage evolution is monitored using acoustic emissions. Histograms of the relative distances between damage events in the numerical calculations and acoustic events in the experiments exhibit good agreement. It is shown that the mesoscale model provides relevant information from the point of view of both global responses and the local failure process. © 2015 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd.

  20. Effects of viscosity in a partially ionized channel flow with thermionic emission

    SciTech Connect

    Mikellides, Ioannis G.

    2009-01-15

    The flow of the partially ionized gas inside thermionic hollow cathodes spans a diverse range of theoretical disciplines in plasma physics and fluid mechanics. Understanding and predicting the evolution of such flows has many practical implications because hollow cathodes are critical components of electric propulsion systems used onboard scientific and commercial spacecraft presently in space or in the mission planning stages. As space missions become more demanding of the propulsion system in terms of throughput, understanding and predicting failure mechanisms of the system becomes imperative. Two-dimensional numerical simulations of the partially ionized gas generated by a thermionic hollow cathode have been performed to quantify the effects of viscosity inside the cylindrical channel of the device. A comparison of the inviscid and fully viscous flow fields shows that viscosity has a significant impact on the atomic species and a lesser effect on the ions. The internal pressure is determined to be more than 40% higher compared to the inviscid solution and the Reynolds number for the flow of atoms is found to be less than 20 inside the channel. Although the Mach number is computed to be <0.1 for approximately 95% of the channel, the solution for the velocity flow field begins to deviate from the Poiseuille (parabolic) solution at about 50% of the channel due mainly to collisional drag with ions.

  1. Lattice QCD

    SciTech Connect

    Bornyakov, V.G.

    2005-06-01

    Possibilities that are provided by a lattice regularization of QCD for studying nonperturbative properties of QCD are discussed. A review of some recent results obtained from computer calculations in lattice QCD is given. In particular, the results for the QCD vacuum structure, the hadron mass spectrum, and the strong coupling constant are considered.

  2. The optical potential on the lattice

    NASA Astrophysics Data System (ADS)

    Agadjanov, Dimitri; Döring, Michael; Mai, Maxim; Meißner, Ulf-G.; Rusetsky, Akaki

    2016-06-01

    The extraction of hadron-hadron scattering parameters from lattice data by using the Lüscher approach becomes increasingly complicated in the presence of inelastic channels. We propose a method for the direct extraction of the complex hadron-hadron optical potential on the lattice, which does not require the use of the multi-channel Lüscher formalism. Moreover, this method is applicable without modifications if some inelastic channels contain three or more particles.

  3. The optical potential on the lattice

    SciTech Connect

    Agadjanov, Dimitri; Doring, Michael; Mai, Maxim; MeiBner, Ulf -G.; Rusetsky, Akaki

    2016-06-08

    The extraction of hadron-hadron scattering parameters from lattice data by using the Luscher approach becomes increasingly complicated in the presence of inelastic channels. We propose a method for the direct extraction of the complex hadron-hadron optical potential on the lattice, which does not require the use of the multi-channel Luscher formalism. Furthermore, this method is applicable without modifications if some inelastic channels contain three or more particles.

  4. The optical potential on the lattice

    DOE PAGES

    Agadjanov, Dimitri; Doring, Michael; Mai, Maxim; ...

    2016-06-08

    The extraction of hadron-hadron scattering parameters from lattice data by using the Luscher approach becomes increasingly complicated in the presence of inelastic channels. We propose a method for the direct extraction of the complex hadron-hadron optical potential on the lattice, which does not require the use of the multi-channel Luscher formalism. Furthermore, this method is applicable without modifications if some inelastic channels contain three or more particles.

  5. Use of a bilayer lattice-matched AlInGaN barrier for improving the channel carrier confinement of enhancement-mode AlInGaN/GaN hetero-structure field-effect transistors

    NASA Astrophysics Data System (ADS)

    Rahbardar Mojaver, Hassan; Gosselin, Jean-Lou; Valizadeh, Pouya

    2017-06-01

    A quaternary lattice-matched layer structure based on employing a bilayer barrier for improving the carrier confinement in the channel of enhancement-mode metal-face c-plane wurtzite AlInGaN/GaN hetero-structure field effect transistors (HFETs) is for the first time proposed. Using the commercial self-consistent Poisson-Schrödinger solver Nextnano, electronic properties of the proposed hetero-structure, including the sheet charge density and carrier confinement on the GaN side of the hetero-interface, are evaluated. Based on these evaluations, it is shown that while the proposed layer structure substantially improves the carrier confinement in the GaN channel layer, it also upholds the merits of employing a lattice-matched barrier towards achieving an enhancement-mode operation (i.e., in the absence of the piezoelectric effect). According to these simulations, in terms of maintaining the required positive threshold-voltage for the enhancement-mode operation, it is also shown that the proposed layer structure substantially outperforms the quaternary AlInGaN/GaN HFETs employing a thin AlN spacer layer.

  6. Study of the Zc+ channel using lattice QCD

    SciTech Connect

    Prelovsek, Sasa; Lang, C. B.; Leskovec, Luka; Mohler, Daniel

    2015-01-01

    Recently experimentalists have discovered several charged charmoniumlike hadrons Zc+ with unconventional quark content c¯cd¯u. We perform a search for Zc+ with mass below 4.2 GeV in the channel IG(JPC)=1+(1+-) using lattice QCD. The major challenge is presented by the two-meson states J/ψπ, ψ2Sπ, ψ1D

  7. Design and characterization of a 32-channel heterodyne radiometer for electron cyclotron emission measurements on experimental advanced superconducting tokamak

    SciTech Connect

    Han, X.; Liu, X.; Liu, Y. Li, E. Z.; Hu, L. Q.; Gao, X.; Domier, C. W.; Luhmann, N. C.

    2014-07-15

    A 32-channel heterodyne radiometer has been developed for the measurement of electron cyclotron emission (ECE) on the experimental advanced superconducting tokamak (EAST). This system collects X-mode ECE radiation spanning a frequency range of 104–168 GHz, where the frequency coverage corresponds to a full radial coverage for the case with a toroidal magnetic field of 2.3 T. The frequency range is equally spaced every 2 GHz from 105.1 to 167.1 GHz with an RF bandwidth of ∼500 MHz and the video bandwidth can be switched among 50, 100, 200, and 400 kHz. Design objectives and characterization of the system are presented in this paper. Preliminary results for plasma operation are also presented.

  8. Use of silicon photovoltaic cells to provide a second channel in flame emission photometry

    PubMed Central

    Hurst, R. J.; Bold, A. M.

    1966-01-01

    Sodium and potassium may be measured simultaneously, using a modified Eppendorf flame photometer. After automatic sampling and dilution of the plasma, the potassium content is measured, using the existing Eppendorf optical and photomultiplier system. The sodium emission is measured by three silicon photovoltaic cells mounted behind an interference filter for sodium, sited on the atomiser casing. The outputs from the photomultiplier and from the silicon cells are recorded by two sensitive recorders. Sixty samples an hour may be estimated, using only 0·12 ml. plasma. Reproducibility tests showed a coefficient of variation of 0·4%. Images PMID:5928613

  9. A lattice relaxation algorithm for three-dimensional Poisson-Nernst-Planck theory with application to ion transport through the gramicidin A channel.

    PubMed Central

    Kurnikova, M G; Coalson, R D; Graf, P; Nitzan, A

    1999-01-01

    A lattice relaxation algorithm is developed to solve the Poisson-Nernst-Planck (PNP) equations for ion transport through arbitrary three-dimensional volumes. Calculations of systems characterized by simple parallel plate and cylindrical pore geometries are presented in order to calibrate the accuracy of the method. A study of ion transport through gramicidin A dimer is carried out within this PNP framework. Good agreement with experimental measurements is obtained. Strengths and weaknesses of the PNP approach are discussed. PMID:9929470

  10. A lattice relaxation algorithm for three-dimensional Poisson-Nernst-Planck theory with application to ion transport through the gramicidin A channel.

    PubMed

    Kurnikova, M G; Coalson, R D; Graf, P; Nitzan, A

    1999-02-01

    A lattice relaxation algorithm is developed to solve the Poisson-Nernst-Planck (PNP) equations for ion transport through arbitrary three-dimensional volumes. Calculations of systems characterized by simple parallel plate and cylindrical pore geometries are presented in order to calibrate the accuracy of the method. A study of ion transport through gramicidin A dimer is carried out within this PNP framework. Good agreement with experimental measurements is obtained. Strengths and weaknesses of the PNP approach are discussed.

  11. Denitrification capacity and greenhouse gas emissions of soils in channelized and restored reaches along an Alpine river corridor

    NASA Astrophysics Data System (ADS)

    Shrestha, Juna; Niklaus, Pascal; Samaritani, Emanuela; Frossard, Emmanuel; Tockner, Klement; Luster, Jörg

    2010-05-01

    In order to assess the effects of river restoration on water and air quality, the biogeochemical functions of channelized and restored river reaches have to be quantified. The objective of this study was to compare denitrification potential and greenhouse gas emissions of functional processing zones (FPZ) in a channelized and a recently restored reach of the alpine river Thur in north-eastern Switzerland. The study was part of the project cluster RECORD of the ETH domain, Switzerland, which was initiated to increase the mechanistic understanding of coupled hydrological and ecological processes in river corridors. The denitrification potential represents an important aspect of the soil filter function related to water quality. Besides, it also contributes to the emission of greenhouse gases. Extensively used pasture growing on a sandy loam is the characteristic FPZ of the channelized section. The restored section encompasses five FPZ: (i) bare gravel bars sparsely colonized by plants, (ii) gravel bars densely colonized by grass (mainly canary reed grass with up to 80 cm sandy deposits), (iii) mixed forest dominated by ash and maple, (iv) riparian forest dominated by willow (Salix alba), (v) older overbank sediments stabilized during restoration with young willows separating the forests from the river-gravel bar system (willow bush). The FPZ were sampled in January, April, August and October 2009. In addition, in June and July 2009 two flood events were monitored in the restored section with more frequent samplings. At each date, topsoil samples were collected in each FPZ (four replicates per samples) and analyzed for denitrifier enzyme activity (DEA). In addition, gas samples were taken in-situ using the closed chamber technique to measure soil respiration as well as N2O and CH4 fluxes. In all FPZ, the denitrification potential was mainly governed by soil moisture. It was highest in the willow forest exhibiting low spatial variability. The DEA in pasture, grass zone

  12. Channeling, volume reflection and gamma emission using 14GeV electrons in bent silicon crystals - Oral presentation

    SciTech Connect

    Benson, Brandon

    2015-08-23

    High energy electrons can be deflected with very tight bending radius using a bent silicon crystal. This produces gamma radiation. As these crystals can be thin, a series of bent silicon crystals with alternating direction has the potential to produce coherent gamma radiation with reasonable energy of the driving electron beam. Such an electron crystal undulator offers the prospect for higher energy radiation at lower cost than current methods. Permanent magnetic undulators like LCLS at SLAC National Accelerator Laboratory are expensive and very large (about 100 m in case of the LCLS undulator). Silicon crystals are inexpensive and compact when compared to the large magnetic undulators. Additionally, such a high energy coherent light source could be used for probing through materials currently impenetrable by x-rays. In this work we present the experimental data and analysis of experiment T523 conducted at SLAC National Accelerator Laboratory. We collected the spectrum of gamma ray emission from 14 GeV electrons on a bent silicon crystal counting single photons. We also investigated the dynamics of electron motion in the crystal i.e. processes of channeling and volume reflection at 14 GeV, extending and building off previous work. Our single photon spectrum for the amorphous crystal orientation is consistent with bremsstrahlung radiation and the volume reflection crystal orientation shows a trend consistent with synchrotron radiation at a critical energy of 740 MeV. We observe that in these two cases the data are consistent, but we make no further claims because of statistical limitations. We also extended the known energy range of electron crystal dechanneling length and channeling efficiency to 14 GeV.

  13. Radiative parameters for multi-channel visible and near-infrared emission transitions of Sm3+ in heavy-metal-silicate glasses

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Zhai, Bin; Zhao, Xin; Wang, Zhiqiang; Lin, Hai

    2013-05-01

    Multi-channel visible and near-infrared (NIR) emission transitions originating from 4G5/2 emitting state of Sm3+ in cadmium-aluminum-silicate (CAS) glasses with maximum-phonon-energy of ˜980 cm-1 have been investigated. Based on the measured absorption spectrum, the Judd-Ofelt parameters Ωt (t=2, 4, 6) are derived to be 2.87×10-20, 3.34×10-20 and 1.86×10-20 cm2, respectively. From the evaluated Judd-Ofelt parameters, the radiative parameters such as spontaneous emission probabilities (Arad), branching ratios (β), and radiative lifetime (τrad) are obtained from the 4G5/2 excited level to different lower energy levels. The efficient visible and NIR transition emissions have been observed in the Sm3+ doped CAS glasses, and the maximum stimulated emission cross-sections (σe-max) corresponding to emission peaks are calculated and demonstrated to lay in the same order of magnitude. The quantum efficiency of 4G5/2 level of Sm3+ has been derived to be 60%. Investigations on multi-channel radiative transition emissions originated from 4G5/2 level of Sm3+ in CAS glasses expose its potential applications in tunable laser, medical light source and NIR optoelectronic devices.

  14. Lattice overview

    SciTech Connect

    Creutz, M.

    1984-01-01

    After reviewing some recent developments in supercomputer access, the author discusses a few areas where perturbation theory and lattice gauge simulations make contact. The author concludes with a brief discussion of a deterministic dynamics for the Ising model. This may be useful for numerical studies of nonequilibrium phenomena. 13 references.

  15. Lattice fermions

    NASA Technical Reports Server (NTRS)

    Wilczek, Frank

    1987-01-01

    A simple heuristic proof of the Nielsen-Ninomaya theorem is given. A method is proposed whereby the multiplication of fermion species on a lattice is reduced to the minimal doubling, in any dimension, with retention of appropriate chiral symmetries. Also, it is suggested that use of spatially thinned fermion fields is likely to be a useful and appropriate approximation in QCD - in any case, it is a self-checking one.

  16. Source attribution and quantification of benzene event emissions in a Houston ship channel community based on real-time mobile monitoring of ambient air.

    PubMed

    Olaguer, Eduardo P; Erickson, Matthew H; Wijesinghe, Asanga; Neish, Bradley S

    2016-02-01

    A mobile laboratory equipped with a proton transfer reaction mass spectrometer (PTR-MS) operated in Galena Park, Texas, near the Houston Ship Channel during the Benzene and other Toxics Exposure Study (BEE-TEX). The mobile laboratory measured transient peaks of benzene of up to 37 ppbv in the afternoon and evening of February 19, 2015. Plume reconstruction and source attribution were performed using the four-dimensional (4D) variational data assimilation technique and a three-dimensional (3D) micro-scale forward and adjoint air quality model based on mobile PTR-MS data and nearby stationary wind measurements at the Galena Park Continuous Air Monitoring Station (CAMS). The results of inverse modeling indicate that significant pipeline emissions of benzene may at least partly explain the ambient concentration peaks observed in Galena Park during BEE-TEX. Total pipeline emissions of benzene inferred within the 16-km(2) model domain exceeded point source emissions by roughly a factor of 2 during the observational episode. Besides pipeline leaks, the model also inferred significant benzene emissions from marine, railcar, and tank truck loading/unloading facilities, consistent with the presence of a tanker and barges in the Kinder Morgan port terminal during the afternoon and evening of February 19. Total domain emissions of benzene exceeded corresponding 2011 National Emissions Inventory (NEI) estimates by a factor of 2-6. Port operations involving petrochemicals may significantly increase emissions of air toxics from the transfer and storage of materials. Pipeline leaks, in particular, can lead to sporadic emissions greater than in emission inventories, resulting in higher ambient concentrations than are sampled by the existing monitoring network. The use of updated methods for ambient monitoring and source attribution in real time should be encouraged as an alternative to expanding the conventional monitoring network.

  17. Angular emission from 1D and 2D meso- and nano-structures: Probed by dual-channel Fourier-plane microscopy

    NASA Astrophysics Data System (ADS)

    Singh, Danveer; Sharma, Deepak Kumar; Chaubey, Shailendra Kumar; Kumar, G. V. Pavan

    2017-09-01

    The optical emission characteristics from individual nanostructures such as organic waveguides, plasmonic nanowires and 2D materials such as MoS2 can vary depending on the nature of interface on which they are grown or deposited. We constructed a dual-channel Fourier-plane microscopy, and studied the directional emission characteristics of an individual organic mesowires, Ag nanowires and MoS2 nanolayers through the glass substrate or air superstrate. Specifically, we show the ability of our microscope to quantitatively probe the radial and azimuthal angular spread in the waveguided PL from the distal ends of the mesowire across the interface without changing its position or orientation. Furthermore, from the guided PL spectral signatures, we show that the finesse of the waveguided Fabry-Perot resonance depends on whether the measurement was performed through the substrate or superstrate. To reveal the versatility of our microscope, we have quantified angular distribution of directional light scattering from the distal end of Ag nanowire at an interface, and angular distribution of excitonic emission from MoS2 nanolayers through a glass substrate. Our work highlights the capability of dual-channel Fourier microscope in quantifying the angular emission characteristics from individual optical antenna structures at an interface, and can be extrapolated to nonlinear organic nanophotonic regimes.

  18. Transmission Electron Microscope Measures Lattice Parameters

    NASA Technical Reports Server (NTRS)

    Pike, William T.

    1996-01-01

    Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.

  19. Transmission Electron Microscope Measures Lattice Parameters

    NASA Technical Reports Server (NTRS)

    Pike, William T.

    1996-01-01

    Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.

  20. Evaluation of the Industrial Point Source Emission Inventory for the Houston Ship Channel Area Using Ship-Based, High-Time-Resolution Measurements of Volatile Organic Compounds

    NASA Astrophysics Data System (ADS)

    Bon, D.; de Gouw, J. A.; Gilman, J. B.; Kuster, W. C.; Lerner, B. M.; Williams, E. J.; Frost, G. J.

    2010-12-01

    Proton Transfer Reaction Ion Trap Mass Spectrometry (PIT-MS) was used to characterize several large (>100 ppbv) industrial volatile organic compound (VOC) plumes in the Houston, Texas Ship Channel observed from the NOAA R/V Ronald H. Brown during the 2006 Texas Air Quality Study (TexAQS) field campaign. Because the ship was sampling close to numerous large emission sources, many of the observed plumes were highly transient making the PIT-MS, with its high time resolution and continuous full mass scan capability, a very useful tool for VOC characterization of the plumes. Plume compositions are compared to the TexAQS2K6 Houston-Galveston-Brazoria Point Source Emission Inventory for individual aromatic compounds; oxygenated VOCs and other selected industrial VOCs observed by PIT-MS. In many cases, we do not find good agreement between the measured plume composition and the VOC speciation in the emissions inventory. These observations are not surprising, as previous research has shown that emission fluxes of individual VOCs may be underestimated by as much as 1-2 orders of magnitude in inventories for the Houston area. In many cases, PIT-MS measurements show clear evidence of industrial emissions not previously identified by the Proton Transfer Reaction (PTR) method. The frequent lack of correlation between large VOC enhancements and enhancements in SO2, NOx and CO suggests large, non-combustion sources of VOCs.

  1. Atom location by electron channeling analysis

    SciTech Connect

    Pennycook, S.J.

    1984-07-01

    For many years the orientation dependence of the characteristic x-ray emission close to a Bragg reflection has been regarded as a hindrance to accurate microanalysis, and a random incident beam direction has always been recommended for accurate composition analysis. However, this orientation dependence can be put to use to extract information on the lattice location of foreign atoms within the crystalline matrix. Here a generalization of the technique is described which is applicable to any crystal structure including monatomic crystals, and can quantitatively determine substitutional fractions of impurities. The technique was referred to as electron channeling analysis, by analogy with the closely related and widely used bulk technique of ion channeling analysis, and was developed for lattice location studies of dopants in semiconductors at high spatial resolution. Only two spectra are required for each channeling analysis, one in each of the channeling conditions described above. If the matrix and dopant x-ray yields vary identically between the two orientations then the dopant necessarily lies within the reflecting matrix planes. If the dopant x-ray yield does not vary the dopant atoms are randomly located with respect to the matrix planes. 10 references, 2 figures.

  2. The world's most spectacular marine hydrocarbon seeps (Coal Oil Point, Santa Barbara Channel, California): Quantification of emissions

    NASA Astrophysics Data System (ADS)

    Hornafius, J. Scott; Quigley, Derek; Luyendyk, Bruce P.

    1999-09-01

    We used 50 kHz sonar data to estimate natural hydrocarbon emission rates from the 18 km2 marine seep field offshore from Coal Oil Point, Santa Barbara, California. The hydrocarbon gas emission rate is 1.7 ± 0.3 × 105 m3 d-1 (including gas captured by a subsea seep containment device) and the associated oil emission rate is 1.6 ± 0.2 × 104 Ld-1 (100 barrels d-1). The nonmethane hydrocarbon emission rate from the gas seepage is 35±7 td-1 and a large source of air pollution in Santa Barbara County. Our estimate is equal to twice the emission rate from all the on-road vehicle traffic in the county. Our estimated methane emission rate for the Coal Oil Point seeps (80±12 td-1) is 4 times higher than previous estimates. The most intense areas of seepage correspond to structural culminations along anticlinal axes. Seep locations are mostly unchanged from those documented in 1946, 1953, and 1973. An exception is the seepage field that once existed near offshore oil platform Holly. A reduction in seepage within a 1 km radius around this offshore platform is correlated with reduced reservoir pressure beneath the natural seeps due to oil production. Our findings suggest that global emissions of methane from natural marine seepage have been underestimated and may be decreasing because of oil production.

  3. Dynamics of lattice kinks

    NASA Astrophysics Data System (ADS)

    Kevrekidis, P. G.; Weinstein, M. I.

    2000-08-01

    We consider a class of Hamiltonian nonlinear wave equations governing a field defined on a spatially discrete one-dimensional lattice, with discreteness parameter, d= h-1, where h>0 is the lattice spacing. The specific cases we consider in detail are the discrete sine-Gordon (SG) and discrete φ4 models. For finite d and in the continuum limit ( d→∞) these equations have static kink-like (heteroclinic) states which are stable. In contrast to the continuum case, due to the breaking of Lorentz invariance, discrete kinks cannot be “Lorentz boosted” to obtain traveling discrete kinks. Peyrard and Kruskal pioneered the study of how a kink, initially propagating in the lattice, dynamically adjusts in the absence of an available family of traveling kinks. We study in detail the final stages of the discrete kink’s evolution during which it is pinned to a specified lattice site (equilibrium position in the Peierls-Nabarro barrier). We find the following: For d sufficiently large (sufficiently small lattice spacing), the state of the system approaches an asymptotically stable ground state static kink (centered between lattice sites). For d sufficiently small, d< d*, the static kink bifurcates to one or more time-periodic states. For the discrete φ4 we have wobbling kinks which have the same spatial symmetry as the static kink as well as “ g-wobblers” and “ e-wobblers”, which have different spatial symmetry. In the discrete SG case, the “ e-wobbler” has the spatial symmetry of the kink, whereas the “ g-wobbler” has the opposite one. These time-periodic states may be regarded as a class of discrete breather/topological defect states; they are spatially localized and time-periodic oscillations mounted on a static kink background. The large time limit of solutions with initial data near a kink is marked by damped oscillation about one of these two types of asymptotic states. In case (1) we compute the characteristics of the damped oscillation

  4. Mid-infrared laser emission from Cr:ZnS channel waveguide fabricated by femtosecond laser helical writing

    PubMed Central

    Peng, Ya-Pei; Zou, Xiao; Bai, Zhengyuan; Leng, Yuxin; Jiang, Benxue; Jiang, Xiongwei; Zhang, Long

    2015-01-01

    The operation of a mid-infrared laser at 2244 nm in a Cr:ZnS polycrystalline channel waveguide fabricated using direct femtosecond laser writing with a helical movement technique is demonstrated. A maximum power output of 78 mW and an optical-to-optical slope efficiency of 8.6% are achieved. The compact waveguide structure with 2 mm length was obtained through direct femtosecond laser writing, which was moved on a helical trajectory along the laser medium axis and parallel to the writing direction. PMID:26692268

  5. Nucleon-Nucleon Scattering From Fully-Dynamical Lattice QCD

    SciTech Connect

    Konstantinos Orginos; Martin Savage; Paulo Bedaque; Silas Beane

    2006-07-01

    We present results of the first fully-dynamical lattice QCD determination of nucleon-nucleon scattering lengths in the 1 S0 channel and 3 S1 - 3 D1 coupled channels. The calculations are performed with domain-wall valence quarks on the MILC staggered configurations with lattice spacing of b = 0.125 fm in the isospin-symmetric limit, and in the absence of electromagnetic interactions

  6. Exotic damping ring lattices

    SciTech Connect

    Palmer, R.B.

    1987-05-01

    This paper looks at, and compares three types of damping ring lattices: conventional, wiggler lattice with finite ..cap alpha.., wiggler lattice with ..cap alpha.. = 0, and observes the attainable equilibrium emittances for the three cases assuming a constraint on the attainable longitudinal impedance of 0.2 ohms. The emittance obtained are roughly in the ratio 4:2:1 for these cases.

  7. Biological Particle Emissions From a South-East Asian Tropical Rainforest Using a Real- Time Dual Channel UV Fluorescence Bio-Aerosol Spectrometer

    NASA Astrophysics Data System (ADS)

    Gabey, A.; Coe, H.; Gallagher, M.; McFiggans, G.; Kaye, P.; Stanley, W.; Foot, V.

    2008-12-01

    and net emission for all fungal spores is ~1 μ g m-3 and ~50 Tg yr-1. These calculations demonstrate the potential importance of PBA, and in particular fungal spores, for global budgets of organic aerosols, particularly in tropical regions, however uncertainties are extremely large, ranging from 50 - 1000 Tg yr- 1. In this study we use the WIBS-3: a low-cost portable single-particle dual-channel UV fluorescence spectrometer (Kaye et al., 2008) to investigate the dynamics of PBA in real-time within and above a tropical forest of 50 m height in Borneo, Malaysia, to estimate net PBA emissions. Different circadian cycles were observed for bio and non-bio aerosol sources and the factors controlling bioaerosol emissions will be discussed in detail.

  8. Electron-emission yield under electron impact of ceramics used as channel materials in Hall-effect thrusters

    NASA Astrophysics Data System (ADS)

    Tondu, T.; Belhaj, M.; Inguimbert, V.

    2011-11-01

    We report measurement of electron-emission yield (EEY) under the impact of electrons on materials of Hall-effect-thruster (HET) interest: BN, BN-SiO2, and Al2O3. The effects of the material aging (under electron irradiation) on the yield of BN and Al2O3 are investigated. The EEY of BN grows with electron exposure, whereas that of Al2O3 reduces. A simple analysis of our experimental results indicates that these variations are most likely because of surface and near surface composition changes caused by the electron beam. The representativeness of EEY measurements on ceramics that have not suffered from the specific environment of a HET (ion and electron bombardment) is discussed.

  9. Effect of entrance-channel asymmetry on the isospin dependence of nucleon emission in heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Zhang, Fang; Zuo, Wei; Chen, Ji-Yan; Zhou, Zhen-Xiao

    2008-07-01

    Using the isospin- and momentum-dependent hadronic transport model IBUU04, we have investigated the influence of the entrance-channel isospin asymmetry on the sensitivity of the pre-equilibrium neutron/proton ratio to symmetry energy in central heavy-ion collisions induced by high-energy radioactive beams. Our analysis and discussion are based on the dynamical simulations of the three isotopic reaction systems 132Sn+124Sn, 124Sn+112Sn and 112Sn+112Sn which are of the same total proton number but different isospin asymmetry. We find that the kinetic-energy distributions of the pre-equilibrium neutron/proton ratio are quite sensitive to the density-dependence of symmetry energy at incident beam energy E/A = 400 MeV, and the sensitivity increases as the isospin asymmetry of the reaction system increases. Supported by National Natural Science Foundation of China (10575119, 10775061), Knowledge Innovation Project of Chinese Academy of Sciences (KJCX3-SYW-N2), Major State Basic Research Developing Program of China (2007CB815004), CAS/SAFEA International Partnership Program for Creative Research Teams (CXTD-J2005-1), and the Asia-Link Project of the European Commission (CN/ASIA-LINK/008(94791))

  10. Scalar meson spectroscopy with a fine lattice

    NASA Astrophysics Data System (ADS)

    Fu, Zi-Wen; Carleton, DeTar

    2011-10-01

    With sufficiently light u and d quarks the isovector (a0) and isosinglet (f0) scalar meson propagators are dominated at large distances by two-meson states. In the staggered fermion formulation of lattice QCD, taste-symmetry breaking causes a proliferation of multihadron states that complicates the analysis of these channels. Of special interest is the bubble contribution, which makes a considerable contribution to these channels. Using numerical simulation we have measured the correlators for both a0 and f0 channels in the “Asqtad" improved staggered fermion formulation in a MILC fine (a = 0.09 fm) lattice ensemble. We analyze those correlators using rooted staggered chiral perturbation theory (rSχPT) and achieve chiral couplings that are well consistent with previous determinations.

  11. Spin-(3/2) pentaquark resonance signature in lattice QCD

    SciTech Connect

    Lasscock, B.G.; Leinweber, D.B.; Melnitchouk, W.; Thomas, A.W.; Williams, A.G.; Young, R.D.; Zanotti, J.M.

    2005-10-01

    The possible discovery of the {theta}{sup +} pentaquark has motivated a number of studies of its nature using lattice QCD. While all the analyses thus far have focused on spin-(1/2) states, here we report the results of the first exploratory study in quenched lattice QCD of pentaquarks with spin (3/2). For the spin-(3/2) interpolating field we use a product of the standard N and K* operators. We do not find any evidence for the standard lattice resonance signature of attraction (i.e., binding at quark masses near the physical regime) in the J{sup P}=(3/2){sup -} channel. Some evidence of binding is inferred in the isoscalar (3/2){sup +} channel at several quark masses, in accord with the standard lattice resonance signature. This suggests that this is a good candidate for the further study of pentaquarks on the lattice.

  12. Grid refinement for entropic lattice Boltzmann models.

    PubMed

    Dorschner, B; Frapolli, N; Chikatamarla, S S; Karlin, I V

    2016-11-01

    We propose a multidomain grid refinement technique with extensions to entropic incompressible, thermal, and compressible lattice Boltzmann models. Its validity and accuracy are assessed by comparison to available direct numerical simulation and experiment for the simulation of isothermal, thermal, and viscous supersonic flow. In particular, we investigate the advantages of grid refinement for the setups of turbulent channel flow, flow past a sphere, Rayleigh-Bénard convection, as well as the supersonic flow around an airfoil. Special attention is paid to analyzing the adaptive features of entropic lattice Boltzmann models for multigrid simulations.

  13. Lattice calculation of nonleptonic charm decays

    SciTech Connect

    Simone, J.N.

    1991-11-01

    The decays of charmed mesons into two body nonleptonic final states are investigated. Weak interaction amplitudes of interest in these decays are extracted from lattice four-point correlation functions using a effective weak Hamiltonian including effects to order G{sub f} in the weak interactions yet containing effects to all orders in the strong interactions. The lattice calculation allows a quantitative examination of non-spectator processes in charm decays helping to elucidate the role of effects such as color coherence, final state interactions and the importance of the so called weak annihilation process. For D {yields} K{pi}, we find that the non-spectator weak annihilation diagram is not small, and we interpret this as evidence for large final state interactions. Moreover, there is indications of a resonance in the isospin {1/2} channel to which the weak annihilation process contributes exclusively. Findings from the lattice calculation are compared to results from the continuum vacuum saturation approximation and amplitudes are examined within the framework of the 1/N expansion. Factorization and the vacuum saturation approximation are tested for lattice amplitudes by comparing amplitudes extracted from lattice four-point functions with the same amplitude extracted from products of two-point and three-point lattice correlation functions arising out of factorization and vacuum saturation.

  14. Lattice location and thermal stability of implanted Fe in ZnO

    SciTech Connect

    Rita, E.; Wahl, U.; Correia, J.G.; Alves, E.; Soares, J.C.

    2004-11-22

    The emission channeling technique was applied to evaluate the lattice location of implanted {sup 59}Fe in single-crystalline ZnO. The angular distribution of {beta}{sup -} particles emitted by {sup 59}Fe was monitored with a position-sensitive electron detector, following 60 keV low dose (2.0x10{sup 13} cm{sup -2}) room-temperature implantation of the precursor isotope {sup 59}Mn. The emission patterns around the [0001], [1102],[1101], and [2113] directions revealed that following annealing at 800 deg. C, 95(8)% of the Fe atoms occupy ideal substitutional Zn sites with rms displacements of 0.06-0.09 A.

  15. Chaotic behavior of channeling particles.

    PubMed

    Chen, Ling; Kaloyeros, Alain E.; Wang, Guang-Hou

    1994-03-01

    Channeling describes the collimated motion of energetic charged particles along the lattice plane or axis in a crystal. The energetic particles are steered through the channels formed by strings of atomic constituents in the lattice. In the case of planar channeling, the motion of a charged particle between the atomic planes can be periodic or quasiperiodic, such as a simple oscillatory motion in the transverse direction. In practice, however, the periodic motion of the channeling particles can be accompanied by an irregular, chaotic behavior. In this paper, the Moliere potential, which is considered as a good analytical approximation for the interaction of channeling particles with the rows of atoms in the lattice, is used to simulate the channeling behavior of positively charged particles in a tungsten (100) crystal plane. By appropriate selection of channeling parameters, such as the projectile energy E(0) and incident angle psi(0), the transition of channeling particles from regular to chaotic motion is demonstrated. It is argued that the fine structures that appear in the angular scan channeling experiments are due to the particles' chaotic motion.

  16. Lattice invariants for knots

    SciTech Connect

    Janse Van Rensburg, E.J.

    1996-12-31

    The geometry of polygonal knots in the cubic lattice may be used to define some knot invariants. One such invariant is the minimal edge number, which is the minimum number of edges necessary (and sufficient) to construct a lattice knot of given type. In addition, one may also define the minimal (unfolded) surface number, and the minimal (unfolded) boundary number; these are the minimum number of 2-cells necessary to construct an unfolded lattice Seifert surface of a given knot type in the lattice, and the minimum number of edges necessary in a lattice knot to guarantee the existence of an unfolded lattice Seifert surface. In addition, I derive some relations amongst these invariants. 8 refs., 5 figs., 2 tabs.

  17. The EMMA Lattice

    NASA Astrophysics Data System (ADS)

    Berg, J. Scott

    2008-02-01

    EMMA is a 10 to 20 MeV electron ring designed to test our understanding of beam dynamics in a relativistic linear non-scaling fixed field alternating gradient accelerator (FFAG). I will give a basic review of the EMMA lattice parameters. Then I will review the different lattice configurations that we would like to have for EMMA. Finally, I will briefly discuss the process of commissioning each lattice configuration.

  18. Lattice location of phosphorus in n-type homoepitaxial diamond films grown by chemical-vapor deposition

    NASA Astrophysics Data System (ADS)

    Hasegawa, Masataka; Teraji, Tokuyuki; Koizumi, Satoshi

    2001-11-01

    The lattice location of phosphorus dopant atoms in n-type homoepitaxial diamond {111} films grown by chemical-vapor deposition has been investigated by Rutherford backscattering spectrometry and particle-induced x-ray emission under ion-channeling conditions. It is found that phosphorus dopant atoms occupy the substitutional sites almost completely in the host diamond lattice. The substitutional fraction of phosphorus was more than 0.9 for <011> and <111> directions. Present observation implies that the deep ground-state energy level of phosphorus in diamond, which is at 0.6 eV below the bottom of the conduction band, is attributed to the relaxation of surrounding carbon atoms.

  19. Damped Bloch oscillations of cold atoms in optical lattices

    SciTech Connect

    Kolovsky, A.R.; Ponomarev, A.V.; Korsch, H.J.

    2002-11-01

    The paper studies Bloch oscillations of cold neutral atoms in the optical lattice. The effect of spontaneous emission on the dynamics of the system is analyzed both analytically and numerically. The spontaneous emission is shown to cause (i) the decay of Bloch oscillations with the decrement given by the rate of spontaneous emission and (ii) the diffusive spreading of the atoms with a diffusion coefficient depending on both the rate of spontaneous emission and the Bloch frequency.

  20. Exploring Three Nucleon Forces in Lattice QCD

    SciTech Connect

    Doi, Takumi

    2011-10-21

    We study the three nucleon force in N{sub f} = 2 dynamical clover fermion lattice QCD, utilizing the Nambu-Bethe-Salpeter wave function of the three nucleon system. Since parity-odd two nucleon potentials are not available in lattice QCD at this moment, we develop a new formulation to extract the genuine three nucleon force which requires only the information of parity-even two nucleon potentials. In order to handle the extremely expensive calculation cost, we consider a specific three-dimensional coordinate configuration for the three nucleons. We find that the linear setup is advantageous, where nucleons are aligned linearly with equal spacings. The lattice calculation is performed with 16{sup 3}x32 configurations at {beta} = 1.95, m{sub {pi}} = 1.13 GeV generated by CP-PACS Collaboration, and the result of the three nucleon force in triton channel is presented.

  1. Dissipative photonic lattice solitons.

    PubMed

    Ultanir, Erdem A; Stegeman, George I; Christodoulides, Demetrios N

    2004-04-15

    We show that discrete dissipative optical lattice solitons are possible in waveguide array configurations that involve periodically patterned semiconductor optical amplifiers and saturable absorbers. The characteristics of these low-power soliton states are investigated, and their propagation constant eigenvalues are mapped on Floquet-Bloch band diagrams. The prospect of observing such low-power dissipative lattice solitons is discussed in detail.

  2. Sensitivity of Satellite-Based Skin Temperature to Different Surface Emissivity and NWP Reanalysis Sources Demonstrated Using a Single-Channel, Viewing-Angle-Corrected Retrieval Algorithm

    NASA Astrophysics Data System (ADS)

    Scarino, B. R.; Minnis, P.; Yost, C. R.; Chee, T.; Palikonda, R.

    2015-12-01

    Single-channel algorithms for satellite thermal-infrared- (TIR-) derived land and sea surface skin temperature (LST and SST) are advantageous in that they can be easily applied to a variety of satellite sensors. They can also accommodate decade-spanning instrument series, particularly for periods when split-window capabilities are not available. However, the benefit of one unified retrieval methodology for all sensors comes at the cost of critical sensitivity to surface emissivity (ɛs) and atmospheric transmittance estimation. It has been demonstrated that as little as 0.01 variance in ɛs can amount to more than a 0.5-K adjustment in retrieved LST values. Atmospheric transmittance requires calculations that employ vertical profiles of temperature and humidity from numerical weather prediction (NWP) models. Selection of a given NWP model can significantly affect LST and SST agreement relative to their respective validation sources. Thus, it is necessary to understand the accuracies of the retrievals for various NWP models to ensure the best LST/SST retrievals. The sensitivities of the single-channel retrievals to surface emittance and NWP profiles are investigated using NASA Langley historic land and ocean clear-sky skin temperature (Ts) values derived from high-resolution 11-μm TIR brightness temperature measured from geostationary satellites (GEOSat) and Advanced Very High Resolution Radiometers (AVHRR). It is shown that mean GEOSat-derived, anisotropy-corrected LST can vary by up to ±0.8 K depending on whether CERES or MODIS ɛs sources are used. Furthermore, the use of either NOAA Global Forecast System (GFS) or NASA Goddard Modern-Era Retrospective Analysis for Research and Applications (MERRA) for the radiative transfer model initial atmospheric state can account for more than 0.5-K variation in mean Ts. The results are compared to measurements from the Surface Radiation Budget Network (SURFRAD), an Atmospheric Radiation Measurement (ARM) Program ground

  3. Scalar meson spectroscopy with lattice staggered fermions

    SciTech Connect

    Bernard, Claude; DeTar, Carleton; Fu Ziwen; Prelovsek, Sasa

    2007-11-01

    With sufficiently light up and down quarks the isovector (a{sub 0}) and isosinglet (f{sub 0}) scalar meson propagators are dominated at large distance by two-meson states. In the staggered-fermion formulation of lattice quantum chromodynamics, taste-symmetry breaking causes a proliferation of two-meson states that further complicates the analysis of these channels. Many of them are unphysical artifacts of the lattice approximation. They are expected to disappear in the continuum limit. The staggered-fermion fourth-root procedure has its purported counterpart in rooted staggered chiral perturbation theory (rS{chi}PT). Fortunately, the rooted theory provides a strict framework that permits the analysis of scalar meson correlators in terms of only a small number of low-energy couplings. Thus the analysis of the point-to-point scalar meson correlators in this context gives a useful consistency check of the fourth-root procedure and its proposed chiral realization. Through numerical simulation we have measured correlators for both the a{sub 0} and f{sub 0} channels in the 'Asqtad' improved staggered-fermion formulation in a lattice ensemble with lattice spacing a=0.12 fm. We analyze those correlators in the context of rS{chi}PT and obtain values of the low-energy chiral couplings that are reasonably consistent with previous determinations.

  4. BB Potentials in Quenched Lattice QCD

    SciTech Connect

    William Detmold; Kostas Orginos; Martin J. Savage

    2007-12-01

    The potentials between two B-mesons are computed in the heavy-quark limit using quenched lattice QCD at $m_\\pi\\sim 400~{\\rm MeV}$. Non-zero central potentials are clearly evident in all four spin-isospin channels, (I,s_l) = (0,0) , (0,1) , (1,0) , (1,1), where s_l is the total spin of the light degrees of freedom. At short distance, we find repulsion in the $I\

  5. Lattice QCD studies of pentaquarks and exotics

    SciTech Connect

    Ben Lasscock; John Hedditch; Waseem Kamleh; Derek Leinweber; Wolodymyr Melnitchouk; Anthony Thomas; Anthony Williams; Ross Young; James Zanotti

    2005-09-14

    The possible discovery of the {Theta}{sup +} pentaquark has motivated a number of studies into its nature using lattice QCD. Initial studies focused on spin-1/2 states and more recently also spin-3/2 states. Here we report the results of the first exploratory study in quenched lattice QCD of pentaquarks with both spin-1/2 and spin-3/2 using the FLIC fermion action. We do not find any evidence for the standard lattice resonance signature of attraction (i.e. binding at quark masses near the physical regime) in the spin-1/2 channels or in the J{sup P} = 3/2{sup -} channel. Some evidence of binding is inferred in the isoscalar 3/2{sup +} channel. We also present the results of our study into exotic meson states using hybrid meson interpolators with explicit gluonic degrees of freedom. We find a candidate for the J{sup PC} = 1{sup {-+}} exotic meson which has a mass consistent with the {pi}{sub 1}(1600) experimental candidate.

  6. Quasicrystallography from Bn lattices

    NASA Astrophysics Data System (ADS)

    Koca, M.; Koca, N. O.; Al-Mukhaini, A.; Al-Qanabi, A.

    2014-11-01

    We present a group theoretical analysis of the hypercubic lattice described by the affine Coxeter-Weyl group Wa (Bn). An h-fold symmetric quasicrystal structure follows from the hyperqubic lattice whose point group is described by the Coxeter-Weyl group W (Bn) with the Coxeter number h=2n. Higher dimensional cubic lattices are explicitly constructed for n = 4,5,6 by identifying their rank-3 Coxeter subgroups and maximal dihedral subgroups. Decomposition of their Voronoi cells under the respective rank-3 subgroups W (A3), W (H2)×W (A1) and W (H3)lead to the rhombic dodecahedron, rhombic icosahedron and rhombic triacontahedron respectively. Projection of the lattice B4 describes a quasicrystal structure with 8-fold symmetry. The B5 lattice leads to quasicrystals with both 5fold and 10 fold symmetries. The lattice B6 projects on a 12-fold symmetric quasicrystal as well as a 3D icosahedral quasicrystal depending on the choice of subspace of projections. The projected sets of lattice points are compatible with the available experimental data.

  7. Superalloy Lattice Block Structures

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Nathal, M. V.; Hebsur, M. G.; Kraus, D. L.

    2003-01-01

    In their simplest form, lattice block panels are produced by direct casting and result in lightweight, fully triangulated truss-like configurations which provide strength and stiffness [2]. The earliest realizations of lattice block were made from A1 and steels, primarily under funding from the US Navy [3]. This work also showed that the mechanical efficiency (eg., specific stiffness) of lattice block structures approached that of honeycomb structures [2]. The lattice architectures are also less anisotropic, and the investment casting route should provide a large advantage in cost and temperature capability over honeycombs which are limited to alloys that can be processed into foils. Based on this early work, a program was initiated to determine the feasibility of extending the high temperature superalloy lattice block [3]. The objective of this effort was to provide an alternative to intermetallics and composites in achieving a lightweight high temperature structure without sacrificing the damage tolerance and moderate cost inherent in superalloys. To establish the feasibility of the superalloy lattice block concept, work was performed in conjunction with JAMCORP, Inc. Billerica, MA, to produce a number of lattice block panels from both IN71 8 and Mar-M247.

  8. A realistic lattice example

    SciTech Connect

    Courant, E.D.; Garren, A.A.

    1985-10-01

    A realistic, distributed interaction region (IR) lattice has been designed that includes new components discussed in the June 1985 lattice workshop. Unlike the test lattices, the lattice presented here includes utility straights and the mechanism for crossing the beams in the experimental straights. Moreover, both the phase trombones and the dispersion suppressors contain the same bending as the normal cells. Vertically separated beams and 6 Tesla, 1-in-1 magnets are assumed. Since the cells are 200 meters long, and have 60 degree phase advance, this lattice has been named RLD1, in analogy with the corresponding test lattice, TLD1. The quadrupole gradient is 136 tesla/meter in the cells, and has similar values in other quadrupoles except in those in the IR`s, where the maximum gradient is 245 tesla/meter. RLD1 has distributed IR`s; however, clustered realistic lattices can easily be assembled from the same components, as was recently done in a version that utilizes the same type of experimental and utility straights as those of RLD1.

  9. Ultracold nonreactive molecules in an optical lattice: connecting chemistry to many-body physics

    NASA Astrophysics Data System (ADS)

    Mukherjee, Rick; Ewart, Kevin; Alam, Shah; Wall, Michael; Doçaj, Andris; Hazzard, Kaden

    2016-05-01

    We derive effective lattice models for ultracold bosonic or fermionic nonreactive molecules (NRMs) in an optical lattice. In stark contrast to the standard Hubbard model, which is commonly assumed to accurately describe NRMs, we find that the single on-site interaction parameter U is replaced by a multi-channel interaction. The complex, multi-channel collisional physics is unrelated to dipolar interactions, and so occurs even in the absence of an electric field or for homonuclear molecules. We find a crossover between coherent few-channel models and fully incoherent single-channel models as the lattice depth is increased. We devise ways to control the effective model parameters using external fields and lattice anisotropy. We show that these parameters can be determined in lattice modulation experiments, which measure molecular collision dynamics with a vastly sharper energy resolution than experiments in an ultracold gas. We will report our progress calculating this novel model's ground state phase diagram.

  10. Features of angular dependence of secondary electron emission from metal single crystals

    NASA Astrophysics Data System (ADS)

    Minnebaev, K. F.; Khaidarov, A. A.; Ivanenko, I. P.; Minnebaev, D. K.; Yurasova, V. E.

    2017-09-01

    The dependence of secondary electron emission coefficient σ on the angle α of primary electron incidence onto single crystals of metals with different crystalline lattice has been studied for undisturbed surface and for disturbed one by sputtering. We used the single crystals of Cu (fcc), Mo (bcc), Zn (hcp) and Ni4Mo (tetragonal lattice). It was shown that the coefficient σ is smaller for the disturbed surface, than for initial one due to absorption of secondary and scattered electrons by the lateral surfaces of hills and cones which are formed as a result of sputtering. For the initial surfaces (of Cu, Mo and Ni4Mo) the maxima of σ(α) in the low-index directions of the crystal lattice arise as a result of primary and secondary electron scattering on the atoms in open channels. At the same time, for the preliminary highly oxidized single crystal surface (of Zn) the minimum of σ in the direction of open channel was observed. The last can be explained by a reduction of work function of surface, and increase in penetration depth of electrons in open channel and by a rise of electron-phonon interaction. Angular dependences of secondary electron emission for a sputtered surface have a more complicated structure with the additional maxima and minima caused by interaction of secondary and scattered electrons with a cone-shaped relief.

  11. Jammed lattice sphere packings

    NASA Astrophysics Data System (ADS)

    Kallus, Yoav; Marcotte, Étienne; Torquato, Salvatore

    2013-12-01

    We generate and study an ensemble of isostatic jammed hard-sphere lattices. These lattices are obtained by compression of a periodic system with an adaptive unit cell containing a single sphere until the point of mechanical stability. We present detailed numerical data about the densities, pair correlations, force distributions, and structure factors of such lattices. We show that this model retains many of the crucial structural features of the classical hard-sphere model and propose it as a model for the jamming and glass transitions that enables exploration of much higher dimensions than are usually accessible.

  12. Architecture and Function of Mechanosensitive Membrane Protein Lattices

    NASA Astrophysics Data System (ADS)

    Kahraman, Osman; Koch, Peter D.; Klug, William S.; Haselwandter, Christoph A.

    2016-01-01

    Experiments have revealed that membrane proteins can form two-dimensional clusters with regular translational and orientational protein arrangements, which may allow cells to modulate protein function. However, the physical mechanisms yielding supramolecular organization and collective function of membrane proteins remain largely unknown. Here we show that bilayer-mediated elastic interactions between membrane proteins can yield regular and distinctive lattice architectures of protein clusters, and may provide a link between lattice architecture and lattice function. Using the mechanosensitive channel of large conductance (MscL) as a model system, we obtain relations between the shape of MscL and the supramolecular architecture of MscL lattices. We predict that the tetrameric and pentameric MscL symmetries observed in previous structural studies yield distinct lattice architectures of MscL clusters and that, in turn, these distinct MscL lattice architectures yield distinct lattice activation barriers. Our results suggest general physical mechanisms linking protein symmetry, the lattice architecture of membrane protein clusters, and the collective function of membrane protein lattices.

  13. Micro-channel plate detector

    DOEpatents

    Elam, Jeffrey W.; Lee, Seon W.; Wang, Hsien -Hau; Pellin, Michael J.; Byrum, Karen; Frisch, Henry J.

    2015-09-22

    A method and system for providing a micro-channel plate detector. An anodized aluminum oxide membrane is provided and includes a plurality of nanopores which have an Al coating and a thin layer of an emissive oxide material responsive to incident radiation, thereby providing a plurality of radiation sensitive channels for the micro-channel plate detector.

  14. Quantum oscillation and decoherence in triangular antidot lattice

    NASA Astrophysics Data System (ADS)

    Ueki, M.; Endo, A.; Katsumoto, S.; Iye, Y.

    2004-04-01

    Quantum oscillation phenomena in triangular antidot lattice have been investigated. Altshuler-Aronov-Spivak oscillations and Aharonov-Bohm (AB)-type oscillations are observed at low magnetic field, and AB-type oscillations due to edge channels are observed in the quantum Hall regime. Measurements of the temperature dependence of these oscillations furnish information on the mechanism of decoherence in the antidot lattice, which is compared with the single ring case.

  15. SPIN ON THE LATTICE.

    SciTech Connect

    ORGINOS,K.

    2003-01-07

    I review the current status of hadronic structure computations on the lattice. I describe the basic lattice techniques and difficulties and present some of the latest lattice results; in particular recent results of the RBC group using domain wall fermions are also discussed. In conclusion, lattice computations can play an important role in understanding the hadronic structure and the fundamental properties of Quantum Chromodynamics (QCD). Although some difficulties still exist, several significant steps have been made. Advances in computer technology are expected to play a significant role in pushing these computations closer to the chiral limit and in including dynamical fermions. RBC has already begun preliminary dynamical domain wall fermion computations [49] which we expect to be pushed forward with the arrival of QCD0C. In the near future, we also expect to complete the non-perturbative renormalization of the relevant derivative operators in quenched QCD.

  16. Root lattices and quasicrystals

    NASA Astrophysics Data System (ADS)

    Baake, M.; Joseph, D.; Kramer, P.; Schlottmann, M.

    1990-10-01

    It is shown that root lattices and their reciprocals might serve as the right pool for the construction of quasicrystalline structure models. All noncrystallographic symmetries observed so far are covered in minimal embedding with maximal symmetry.

  17. Root lattices and quasicrystals

    NASA Astrophysics Data System (ADS)

    Baake, M.; Joseph, D.; Kramer, P.; Schlottmann, M.

    1990-10-01

    It is shown how root lattices and their reciprocals might serve as the right pool for the construction of quasicrystalline structure models. All non-periodic symmetries observed so far are covered in minimal embedding with maximal symmetry.

  18. Superalloy Lattice Block Structures

    NASA Technical Reports Server (NTRS)

    Nathal, M. V.; Whittenberger, J. D.; Hebsur, M. G.; Kantzos, P. T.; Krause, D. L.

    2004-01-01

    Initial investigations of investment cast superalloy lattice block suggest that this technology will yield a low cost approach to utilize the high temperature strength and environmental resistance of superalloys in lightweight, damage tolerant structural configurations. Work to date has demonstrated that relatively large superalloy lattice block panels can be successfully investment cast from both IN-718 and Mar-M247. These castings exhibited mechanical properties consistent with the strength of the same superalloys measured from more conventional castings. The lattice block structure also accommodates significant deformation without failure, and is defect tolerant in fatigue. The potential of lattice block structures opens new opportunities for the use of superalloys in future generations of aircraft applications that demand strength and environmental resistance at elevated temperatures along with low weight.

  19. Asymptotic energy of lattices

    NASA Astrophysics Data System (ADS)

    Yan, Weigen; Zhang, Zuhe

    2009-04-01

    The energy of a simple graph G arising in chemical physics, denoted by E(G), is defined as the sum of the absolute values of eigenvalues of G. As the dimer problem and spanning trees problem in statistical physics, in this paper we propose the energy per vertex problem for lattice systems. In general for a type of lattice in statistical physics, to compute the entropy constant with toroidal, cylindrical, Mobius-band, Klein-bottle, and free boundary conditions are different tasks with different hardness and may have different solutions. We show that the energy per vertex of plane lattices is independent of the toroidal, cylindrical, Mobius-band, Klein-bottle, and free boundary conditions. In particular, the asymptotic formulae of energies of the triangular, 33.42, and hexagonal lattices with toroidal, cylindrical, Mobius-band, Klein-bottle, and free boundary conditions are obtained explicitly.

  20. Automated Lattice Perturbation Theory

    SciTech Connect

    Monahan, Christopher

    2014-11-01

    I review recent developments in automated lattice perturbation theory. Starting with an overview of lattice perturbation theory, I focus on the three automation packages currently "on the market": HiPPy/HPsrc, Pastor and PhySyCAl. I highlight some recent applications of these methods, particularly in B physics. In the final section I briefly discuss the related, but distinct, approach of numerical stochastic perturbation theory.

  1. Study of pentaquarks on the lattice with overlap fermions

    SciTech Connect

    Mathur, N.; Alexandru, A.; Dong, S.J.; Draper, T.; Horvath, I.; Liu, K.F.; Tamhankar, S.; Lee, F.X.; Bennhold, C.; Chen, Y.; Zhang, J. B.

    2004-10-01

    We present a quenched lattice QCD calculation of spin-1/2 five-quark states with uudds quark content for both positive and negative parities. We do not observe any bound pentaquark state in these channels for either I=0 or I=1. The states we found are consistent with KN scattering states which are checked to exhibit the expected volume dependence of the spectral weight. The results are based on overlap-fermion propagators on two lattices, 12{sup 3}x28 and 16{sup 3}x28, with the same lattice spacing of 0.2 fm, and pion mass as low as {approx}180 MeV.

  2. Additive lattice kirigami.

    PubMed

    Castle, Toen; Sussman, Daniel M; Tanis, Michael; Kamien, Randall D

    2016-09-01

    Kirigami uses bending, folding, cutting, and pasting to create complex three-dimensional (3D) structures from a flat sheet. In the case of lattice kirigami, this cutting and rejoining introduces defects into an underlying 2D lattice in the form of points of nonzero Gaussian curvature. A set of simple rules was previously used to generate a wide variety of stepped structures; we now pare back these rules to their minimum. This allows us to describe a set of techniques that unify a wide variety of cut-and-paste actions under the rubric of lattice kirigami, including adding new material and rejoining material across arbitrary cuts in the sheet. We also explore the use of more complex lattices and the different structures that consequently arise. Regardless of the choice of lattice, creating complex structures may require multiple overlapping kirigami cuts, where subsequent cuts are not performed on a locally flat lattice. Our additive kirigami method describes such cuts, providing a simple methodology and a set of techniques to build a huge variety of complex 3D shapes.

  3. Additive lattice kirigami

    PubMed Central

    Castle, Toen; Sussman, Daniel M.; Tanis, Michael; Kamien, Randall D.

    2016-01-01

    Kirigami uses bending, folding, cutting, and pasting to create complex three-dimensional (3D) structures from a flat sheet. In the case of lattice kirigami, this cutting and rejoining introduces defects into an underlying 2D lattice in the form of points of nonzero Gaussian curvature. A set of simple rules was previously used to generate a wide variety of stepped structures; we now pare back these rules to their minimum. This allows us to describe a set of techniques that unify a wide variety of cut-and-paste actions under the rubric of lattice kirigami, including adding new material and rejoining material across arbitrary cuts in the sheet. We also explore the use of more complex lattices and the different structures that consequently arise. Regardless of the choice of lattice, creating complex structures may require multiple overlapping kirigami cuts, where subsequent cuts are not performed on a locally flat lattice. Our additive kirigami method describes such cuts, providing a simple methodology and a set of techniques to build a huge variety of complex 3D shapes. PMID:27679822

  4. Legless locomotion in lattices

    NASA Astrophysics Data System (ADS)

    Schiebel, Perrin; Dai, Jin; Gong, Chaohui; Serrano, Miguel M.; Mendelson, Joseph R., III; Choset, Howie; Goldman, Daniel I.

    2015-03-01

    By propagating waves from head to tail, limbless organisms like snakes can traverse terrain composed of rocks, foliage, soil and sand. Previous research elucidated how rigid obstacles influence snake locomotion by studying a model terrain-symmetric lattices of pegs placed in hard ground. We want to understand how different substrate-body interaction modes affect performance in desert-adapted snakes during transit of substrates composed of both rigid obstacles and granular media (GM). We tested Chionactis occipitalis, the Mojave shovel-nosed snake, in two laboratory treatments: lattices of 0 . 64 cm diameter obstacles arrayed on both a hard, slick substrate and in a GM of ~ 0 . 3 mm diameter glass particles. For all lattice spacings, d, speed through the hard ground lattices was less than that in GM lattices. However, maximal undulation efficiencies ηu (number of body lengths advanced per undulation cycle) in both treatments were comparable when d was intermediate. For other d, ηu was lower than this maximum in hard ground lattices, while on GM, ηu was insensitive to d. To systematically explore such locomotion, we tested a physical robot model of the snake; performance depended sensitively on base substrate, d and body wave parameters.

  5. Ghost condensation on the lattice

    SciTech Connect

    Cucchieri, Attilio; Mendes, Tereza; Mihara, Antonio

    2005-11-01

    We perform a numerical study of ghost condensation--in the so-called Overhauser channel--for SU(2) lattice gauge theory in minimal Landau gauge. The off-diagonal components of the momentum-space ghost propagator G{sup cd}(p) are evaluated for lattice volumes V=8{sup 4}, 12{sup 4}, 16{sup 4}, 20{sup 4}, 24{sup 4} and for three values of the lattice coupling: {beta}=2.2, 2.3, 2.4. Our data show that the quantity {phi}{sup b}(p)={epsilon}{sup bcd}G{sup cd}(p)/2 is zero within error bars, being characterized by very large statistical fluctuations. On the contrary, vertical bar {phi}{sup b}(p) vertical bar has relatively small error bars and behaves at small momenta as L{sup -2}p{sup -z}, where L is the lattice side in physical units and z{approx_equal}4. We argue that the large fluctuations for {phi}{sup b}(p) come from spontaneous breaking of a global symmetry and are associated with ghost condensation. It may thus be necessary (in numerical simulations at finite volume) to consider vertical bar {phi}{sup b}(p) vertical bar instead of {phi}{sup b}(p), to avoid a null average due to tunneling between different broken vacua. Also, we show that {phi}{sup b}(p) is proportional to the Fourier-transformed gluon field components A-tilde{sub {mu}}{sup b}(q). This explains the L{sup -2} dependence of vertical bar {phi}{sup b}(p) vertical bar, as induced by the behavior of vertical bar A-tilde{sub {mu}}{sup b}(q) vertical bar. We fit our data for vertical bar {phi}{sup b}(p) vertical bar to the theoretical prediction (r/L{sup 2}+v)/(p{sup 4}+v{sup 2}), obtaining for the ghost condensate v an upper bound of about 0.058 GeV{sup 2}. In order to check if v is nonzero in the continuum limit, one probably needs numerical simulations at much larger physical volumes than the ones we consider. As a by-product of our analysis, we perform a careful study of the color structure of the inverse Faddeev-Popov matrix in momentum space.

  6. Solitons in spiraling Vogel lattices.

    PubMed

    Kartashov, Yaroslav V; Vysloukh, Victor A; Torner, Lluis

    2013-01-15

    We address light propagation in Vogel optical lattices and show that such lattices support a variety of stable soliton solutions in both self-focusing and self-defocusing media, whose propagation constants belong to domains resembling gaps in the spectrum of a truly periodic lattice. The azimuthally rich structure of Vogel lattices allows generation of spiraling soliton motion.

  7. A lattice-Boltzmann scheme of the Navier-Stokes equations on a 3D cuboid lattice

    NASA Astrophysics Data System (ADS)

    Min, Haoda; Peng, Cheng; Wang, Lian-Ping

    2015-11-01

    The standard lattice-Boltzmann method (LBM) for fluid flow simulation is based on a square (in 2D) or cubic (in 3D) lattice grids. Recently, two new lattice Boltzmann schemes have been developed on a 2D rectangular grid using the MRT (multiple-relaxation-time) collision model, by adding a free parameter in the definition of moments or by extending the equilibrium moments. Here we developed a lattice Boltzmann model on 3D cuboid lattice, namely, a lattice grid with different grid lengths in different spatial directions. We designed our MRT-LBM model by matching the moment equations from the Chapman-Enskog expansion with the Navier-Stokes equations. The model guarantees correct hydrodynamics. A second-order term is added to the equilibrium moments in order to restore the isotropy of viscosity on a cuboid lattice. The form and the coefficients of the extended equilibrium moments are determined through an inverse design process. An additional benefit of the model is that the viscosity can be adjusted independent of the stress-moment relaxation parameter, thus improving the numerical stability of the model. The resulting cuboid MRT-LBM model is then validated through benchmark simulations using laminar channel flow, turbulent channel flow, and the 3D Taylor-Green vortex flow.

  8. Hyperon-Nulceon Scattering from Fully-Dynamical Lattice QCD

    SciTech Connect

    Silas Beane; Paulo Bedaque; Thomas Luu; Konstantinos Orginos; Elizabetta Pallante; Assumpta Parreno; Martin Savage

    2007-10-01

    We present results of the first fully-dynamical lattice QCD determination of hyperon-nucleon scattering. One s-wave phase shift was determined for n{Lambda} scattering in both spin-channels at pion masses of 350, 490, and 590 MeV, and for n{Sigma}^- scattering in both spin channels at pion masses of 490, and 590 MeV. The calculations were performed with domain-wall valence quarks on dynamical, staggered gauge configurations with a lattice spacing of b ~0.125 fm.

  9. Realization of non-linear coherent states by photonic lattices

    SciTech Connect

    Dehdashti, Shahram Li, Rujiang; Chen, Hongsheng; Liu, Jiarui Yu, Faxin

    2015-06-15

    In this paper, first, by introducing Holstein-Primakoff representation of α-deformed algebra, we achieve the associated non-linear coherent states, including su(2) and su(1, 1) coherent states. Second, by using waveguide lattices with specific coupling coefficients between neighbouring channels, we generate these non-linear coherent states. In the case of positive values of α, we indicate that the Hilbert size space is finite; therefore, we construct this coherent state with finite channels of waveguide lattices. Finally, we study the field distribution behaviours of these coherent states, by using Mandel Q parameter.

  10. Taylor line swimming in microchannels and cubic lattices of obstacles

    NASA Astrophysics Data System (ADS)

    Münch, Jan L.; Alizadehrad, Davod; Babu, Sujin B.; Stark, Holger

    Microorganisms naturally move in microstructured fluids. Using the simulation method of multi-particle collision dynamics, we study an undulatory Taylor line swimming in a two-dimensional microchannel and in a cubic lattice of obstacles, which represent simple forms of a microstructured environment. In the microchannel the Taylor line swims at an acute angle along a channel wall with a clearly enhanced swimming speed due to hydrodynamic interactions with the bounding wall. While in a dilute obstacle lattice swimming speed is also enhanced, a dense obstacle lattice gives rise to geometric swimming. This new type of swimming is characterized by a drastically increased swimming speed. Since the Taylor line has to fit into the free space of the obstacle lattice, the swimming speed is close to the phase velocity of the bending wave traveling along the Taylor line. While adjusting its swimming motion within the lattice, the Taylor line chooses a specific swimming direction, which we classify by a lattice vector. When plotting the swimming velocity versus the magnitude of the lattice vector, all our data collapse on a single master curve. Finally, we also report more complex trajectories within the obstacle lattice.

  11. Taylor line swimming in microchannels and cubic lattices of obstacles.

    PubMed

    Münch, Jan L; Alizadehrad, Davod; Babu, Sujin B; Stark, Holger

    2016-09-21

    Microorganisms naturally move in microstructured fluids. Using the simulation method of multi-particle collision dynamics, we study in two dimensions an undulatory Taylor line swimming in a microchannel and in a cubic lattice of obstacles, which represent simple forms of a microstructured environment. In the microchannel the Taylor line swims at an acute angle along a channel wall with a clearly enhanced swimming speed due to hydrodynamic interactions with the bounding wall. While in a dilute obstacle lattice swimming speed is also enhanced, a dense obstacle lattice gives rise to geometric swimming. This new type of swimming is characterized by a drastically increased swimming speed. Since the Taylor line has to fit into the free space of the obstacle lattice, the swimming speed is close to the phase velocity of the bending wave traveling along the Taylor line. While adjusting its swimming motion within the lattice, the Taylor line chooses a specific swimming direction, which we classify by a lattice vector. When plotting the swimming velocity versus the magnitude of the lattice vector, all our data collapse on a single master curve. Finally, we also report more complex trajectories within the obstacle lattice.

  12. Light-induced atomic elevator in optical lattices

    NASA Astrophysics Data System (ADS)

    Prants, S. V.

    2016-12-01

    It is shown how an atomic elevator that can elevate falling cold atoms in a vertical optical lattice can be created. The effect appears near resonance owing to the nonlinear interaction between the electronic and mechanical degrees of freedom of an atom, which is responsible for its random walk in rigid optical lattices without any modulation and additional action. Numerical experiments involving spontaneous emission demonstrate that random walk of atoms and light-induced atomic elevator can be observed in a real experiment.

  13. Measuring on Lattices

    NASA Astrophysics Data System (ADS)

    Knuth, Kevin H.

    2009-12-01

    Previous derivations of the sum and product rules of probability theory relied on the algebraic properties of Boolean logic. Here they are derived within a more general framework based on lattice theory. The result is a new foundation of probability theory that encompasses and generalizes both the Cox and Kolmogorov formulations. In this picture probability is a bi-valuation defined on a lattice of statements that quantifies the degree to which one statement implies another. The sum rule is a constraint equation that ensures that valuations are assigned so as to not violate associativity of the lattice join and meet. The product rule is much more interesting in that there are actually two product rules: one is a constraint equation arises from associativity of the direct products of lattices, and the other a constraint equation derived from associativity of changes of context. The generality of this formalism enables one to derive the traditionally assumed condition of additivity in measure theory, as well introduce a general notion of product. To illustrate the generic utility of this novel lattice-theoretic foundation of measure, the sum and product rules are applied to number theory. Further application of these concepts to understand the foundation of quantum mechanics is described in a joint paper in this proceedings.

  14. Time-Dependent Lattice Methods for Ion-Atom Collisions in Cartesian and Cylindrical Coordinate Systems

    SciTech Connect

    Pindzola, Michael S; Schultz, David Robert

    2008-01-01

    Time-dependent lattice methods in both Cartesian and cylindrical coordinates are applied to calculate excitation cross sections for p+H collisions at 40 keV incident energy. The time-dependent Schroedinger equation is solved using a previously formulated Cartesian coordinate single-channel method on a full 3D lattice and a newly formulated cylindrical coordinate multichannel method on a set of coupled 2D lattices. Cartesian coordinate single-channel and cylindrical coordinate five-channel calculations are found to be in reasonable agreement for excitation cross sections from the 1s ground state to the 2s, 2p, 3s, 3p, and 3d excited states. For extension of the time-dependent lattice method to handle the two electron dynamics found in p+He collisions, the cylindrical coordinate multichannel method appears promising due to the reduced dimensionality of its lattice.

  15. Dechanneling of Positrons in Disordered Lattices Effect of Anharmonic Potential

    NASA Astrophysics Data System (ADS)

    Abu-Assy, M. K.; El-Ashry, M. Y.; Mohamed, A. A.

    2005-01-01

    Dechanneling of positrons due to lattice disorder has been investigated for two stable configurations of the disordered face-centered cubic(fcc) lattices, Dumb-bell configuration (DBC) and Body-centered interstitial (BCI) for channeled positrons with incident energy (10 200) MeV in Cu single crystal in the planar direction (100). The effects of anharmonic terms in the channeling potential have been considered in the calculations. The calculations covered the transition-channeling probability, dechanneling probability, transmission and dechanneling coefficients. It has been found that the transition-channeling probability from the normal into the disordered region occurs only for the transitions n (normal) → n (disordered). Also the dependence of the transmission and dechanneling coefficients on the incident beam position has been studied by using a planar potential function based on shell structure model and compared with the results of a planar potential based on Lindhard's model.

  16. Lattice studies of baryons

    SciTech Connect

    David Richards

    2004-10-01

    This talk describes progress at understanding the properties of the nucleon and its excitations from lattice QCD. I begin with a review of recent lattice results for the lowest-lying states of the excited baryon spectrum. The need to approach physical values of the light quark masses is emphasized, enabling the effects of the pion cloud to be revealed. I then outline the development of techniques that will enable the extraction of the masses of the higher resonances, and describe how such calculations provide insight into the structure of the hadrons. Finally, I discuss direct probes of the quark and gluon structure of baryons through the lattice measurement of the moments of quark distributions and of Generalized Parton Distributions.

  17. Crossing on hyperbolic lattices

    NASA Astrophysics Data System (ADS)

    Gu, Hang; Ziff, Robert M.

    2012-05-01

    We divide the circular boundary of a hyperbolic lattice into four equal intervals and study the probability of a percolation crossing between an opposite pair as a function of the bond occupation probability p. We consider the {7,3} (heptagonal), enhanced or extended binary tree (EBT), the EBT-dual, and the {5,5} (pentagonal) lattices. We find that the crossing probability increases gradually from 0 to 1 as p increases from the lower pl to the upper pu critical values. We find bounds and estimates for the values of pl and pu for these lattices and identify the self-duality point p* corresponding to where the crossing probability equals 1/2. Comparison is made with recent numerical and theoretical results.

  18. Lattice gauge theories

    NASA Astrophysics Data System (ADS)

    Weisz, Peter; Majumdar, Pushan

    2012-03-01

    Lattice gauge theory is a formulation of quantum field theory with gauge symmetries on a space-time lattice. This formulation is particularly suitable for describing hadronic phenomena. In this article we review the present status of lattice QCD. We outline some of the computational methods, discuss some phenomenological applications and a variety of non-perturbative topics. The list of references is severely incomplete, the ones we have included are text books or reviews and a few subjectively selected papers. Kronfeld and Quigg (2010) supply a reasonably comprehensive set of QCD references. We apologize for the fact that have not covered many important topics such as QCD at finite density and heavy quark effective theory adequately, and mention some of them only in the last section "In Brief". These topics should be considered in further Scholarpedia articles.

  19. Lattice Boltzmann Stokesian dynamics.

    PubMed

    Ding, E J

    2015-11-01

    Lattice Boltzmann Stokesian dynamics (LBSD) is presented for simulation of particle suspension in Stokes flows. This method is developed from Stokesian dynamics (SD) with resistance and mobility matrices calculated using the time-independent lattice Boltzmann algorithm (TILBA). TILBA is distinguished from the traditional lattice Boltzmann method (LBM) in that a background matrix is generated prior to the calculation. The background matrix, once generated, can be reused for calculations for different scenarios, thus the computational cost for each such subsequent calculation is significantly reduced. The LBSD inherits the merits of the SD where both near- and far-field interactions are considered. It also inherits the merits of the LBM that the computational cost is almost independent of the particle shape.

  20. Precise lattice location of substitutional and interstitial Mg in AlN

    SciTech Connect

    Amorim, L. M.; Pereira, L. M. C.; Decoster, S.; Temst, K.; Vantomme, A.; Wahl, U.; Correia, J. G.; Silva, D. J.; Silva, M. R. da; Gottberg, A.

    2013-12-23

    The lattice site location of radioactive {sup 27}Mg implanted in AlN was determined by means of emission channeling. The majority of the {sup 27}Mg was found to substitute for Al, yet significant fractions (up to 33%) were also identified close to the octahedral interstitial site. The activation energy for interstitial Mg diffusion is estimated to be between 1.1 eV and 1.7 eV. Substitutional Mg is shown to occupy ideal Al sites within a 0.1 Å experimental uncertainty. We discuss the absence of significant displacements from ideal Al sites, in the context of the current debate, on Mg doped nitride semiconductors.

  1. Atoms in non-dissipative optical lattices

    NASA Astrophysics Data System (ADS)

    Bergamini, Silvia

    Optical lattices induced by light detuned far from the frequency of any atomic resonance transition are ideal systems in which to develop techniques for the coherent control of atomic motional and internal states. Decoherence arising from spontaneous emission can be eliminated to an arbitrary degree by varying the detuning of the optical field. The atoms trapped in these lattices are to a large extent isolated from environmental disturbances and from each other. The first step towards the coherent control of atoms in a far-detuned lattice is their preparation in a single motional state. In this thesis the preparation of atoms in the ground vibrational state of a two-dimensional far-detuned optical lattice via resolved-sideband Raman cooling is presented. This sideband-cooling scheme involves stimulated Raman transitions between bound vibrational states of a pair of magnetic ground state sublevels, followed by an irreversible step due to optical pumping, resulting in a net loss of one quantum of vibrational energy per cooling cycle. This process provides efficient cooling in two-dimensions and leads to the accumulation of a large fraction of atoms in the 2-D ground vibrational state of a potential well associated with a single Zeeman substate. Experiments aimed at improving and monitoring the characteristics of the lar-detuned lattice and the sideband-Raman cooling efficiency are also described. Parametric excitation experiments and modelling are employed to investigate the degree of anharmonicity of the optical potential and the importance of heating induced by laser intensity noise, whilst Zeeman-state analysis of the sample is performed for monitoring the distribution of atoms over different magnetic sub- states. Finally, spin-polarization experiments are carried out in order to study the paramagnetic properties of the lattice and lead to an evaluation of a spin-temperature for the sample.

  2. Exact Lattice Supersymmetry

    SciTech Connect

    Catterall, Simon; Kaplan, David B.; Unsal, Mithat

    2009-03-31

    We provide an introduction to recent lattice formulations of supersymmetric theories which are invariant under one or more real supersymmetries at nonzero lattice spacing. These include the especially interesting case of N = 4 SYM in four dimensions. We discuss approaches based both on twisted supersymmetry and orbifold-deconstruction techniques and show their equivalence in the case of gauge theories. The presence of an exact supersymmetry reduces and in some cases eliminates the need for fine tuning to achieve a continuum limit invariant under the full supersymmetry of the target theory. We discuss open problems.

  3. Optical Lattice Clocks

    NASA Astrophysics Data System (ADS)

    Oates, Chris

    2012-06-01

    Since they were first proposed in 2003 [1], optical lattice clocks have become one of the leading technologies for the next generation of atomic clocks, which will be used for advanced timing applications and in tests of fundamental physics [2]. These clocks are based on stabilized lasers whose frequency is ultimately referenced to an ultra-narrow neutral atom transition (natural linewidths << 1 Hz). To suppress the effects of atomic motion/recoil, the atoms in the sample (˜10^4 atoms) are confined tightly in the potential wells of an optical standing wave (lattice). The wavelength of the lattice light is tuned to its ``magic'' value so as to yield a vanishing net AC Stark shift for the clock transition. As a result lattice clocks have demonstrated the capability of generating high stability clock signals with small absolute uncertainties (˜ 1 part in 10^16). In this presentation I will first give an overview of the field, which now includes three different atomic species. I will then use experiments with Yb performed in our laboratory to illustrate the key features of a lattice clock. Our research has included the development of state-of-the-art optical cavities enabling ultra-high-resolution optical spectroscopy (1 Hz linewidth). Together with the large atom number in the optical lattice, we are able to achieve very low clock instability (< 0.3 Hz in 1 s) [3]. Furthermore, I will show results from some of our recent investigations of key shifts for the Yb lattice clock, including high precision measurements of ultracold atom-atom interactions in the lattice and the dc Stark effect for the Yb clock transition (necessary for the evaluation of blackbody radiation shifts). [4pt] [1] H. Katori, M. Takamoto, V. G. Pal'chikov, and V. D. Ovsiannikov, Phys. Rev. Lett. 91, 173005 (2003). [0pt] [2] Andrei Derevianko and Hidetoshi Katori, Rev. Mod. Phys. 83, 331 (2011). [0pt] [3] Y. Y. Jiang, A. D. Ludlow, N. D. Lemke, R. W. Fox, J. A. Sherman, L.-S. Ma, and C. W. Oates

  4. Low lattice thermal conductivity of stanene.

    PubMed

    Peng, Bo; Zhang, Hao; Shao, Hezhu; Xu, Yuchen; Zhang, Xiangchao; Zhu, Heyuan

    2016-02-03

    A fundamental understanding of phonon transport in stanene is crucial to predict the thermal performance in potential stanene-based devices. By combining first-principle calculation and phonon Boltzmann transport equation, we obtain the lattice thermal conductivity of stanene. A much lower thermal conductivity (11.6 W/mK) is observed in stanene, which indicates higher thermoelectric efficiency over other 2D materials. The contributions of acoustic and optical phonons to the lattice thermal conductivity are evaluated. Detailed analysis of phase space for three-phonon processes shows that phonon scattering channels LA + LA/TA/ZA ↔ TA/ZA are restricted, leading to the dominant contributions of high-group-velocity LA phonons to the thermal conductivity. The size dependence of thermal conductivity is investigated as well for the purpose of the design of thermoelectric nanostructures.

  5. Low lattice thermal conductivity of stanene

    NASA Astrophysics Data System (ADS)

    Peng, Bo; Zhang, Hao; Shao, Hezhu; Xu, Yuchen; Zhang, Xiangchao; Zhu, Heyuan

    2016-02-01

    A fundamental understanding of phonon transport in stanene is crucial to predict the thermal performance in potential stanene-based devices. By combining first-principle calculation and phonon Boltzmann transport equation, we obtain the lattice thermal conductivity of stanene. A much lower thermal conductivity (11.6 W/mK) is observed in stanene, which indicates higher thermoelectric efficiency over other 2D materials. The contributions of acoustic and optical phonons to the lattice thermal conductivity are evaluated. Detailed analysis of phase space for three-phonon processes shows that phonon scattering channels LA + LA/TA/ZA ↔ TA/ZA are restricted, leading to the dominant contributions of high-group-velocity LA phonons to the thermal conductivity. The size dependence of thermal conductivity is investigated as well for the purpose of the design of thermoelectric nanostructures.

  6. Low lattice thermal conductivity of stanene

    PubMed Central

    Peng, Bo; Zhang, Hao; Shao, Hezhu; Xu, Yuchen; Zhang, Xiangchao; Zhu, Heyuan

    2016-01-01

    A fundamental understanding of phonon transport in stanene is crucial to predict the thermal performance in potential stanene-based devices. By combining first-principle calculation and phonon Boltzmann transport equation, we obtain the lattice thermal conductivity of stanene. A much lower thermal conductivity (11.6 W/mK) is observed in stanene, which indicates higher thermoelectric efficiency over other 2D materials. The contributions of acoustic and optical phonons to the lattice thermal conductivity are evaluated. Detailed analysis of phase space for three-phonon processes shows that phonon scattering channels LA + LA/TA/ZA ↔ TA/ZA are restricted, leading to the dominant contributions of high-group-velocity LA phonons to the thermal conductivity. The size dependence of thermal conductivity is investigated as well for the purpose of the design of thermoelectric nanostructures. PMID:26838731

  7. Supersymmetry on the Lattice

    NASA Astrophysics Data System (ADS)

    Schaich, David

    2016-03-01

    Lattice field theory provides a non-perturbative regularization of strongly interacting systems, which has proven crucial to the study of quantum chromodynamics among many other theories. Supersymmetry plays prominent roles in the study of physics beyond the standard model, both as an ingredient in model building and as a tool to improve our understanding of quantum field theory. Attempts to apply lattice techniques to supersymmetric field theories have a long history, but until recently these efforts have generally encountered insurmountable difficulties related to the interplay of supersymmetry with the lattice discretization of spacetime. In recent years these difficulties have been overcome for a class of theories that includes the particularly interesting case of maximally supersymmetric Yang-Mills (N = 4 SYM) in four dimensions, which is a cornerstone of AdS/CFT duality. In combination with computational advances this progress enables practical numerical investigations of N = 4 SYM on the lattice, which can address questions that are difficult or impossible to handle through perturbation theory, AdS/CFT duality, or the conformal bootstrap program. I will briefly review some of the new ideas underlying this recent progress, and present some results from ongoing large-scale numerical calculations, including comparisons with analytic predictions.

  8. Fibonacci Optical Lattices

    NASA Astrophysics Data System (ADS)

    Singh, Kevin; Geiger, Zachary; Senaratne, Ruwan; Rajagopal, Shankari; Fujiwara, Kurt; Weld, David; Weld Group Team

    2015-05-01

    Quasiperiodicity is intimately involved in quantum phenomena from localization to the quantum Hall effect. Recent experimental investigation of quasiperiodic quantum effects in photonic and electronic systems have revealed intriguing connections to topological phenomena. However, such experiments have been limited by the absence of techniques for creating tunable quasiperiodic structures. We propose a new type of quasiperiodic optical lattice, constructed by intersecting a Gaussian beam with a 2D square lattice at an angle with an irrational tangent. The resulting potential, a generalization of the Fibonacci lattice, is a physical realization of the mathematical ``cut-and-project'' construction which underlies all quasiperiodic structures. Calculation of the energies and wavefunctions of atoms loaded into the proposed quasiperiodic lattice demonstrate a fractal energy spectrum and the existence of edge states. We acknowledge support from the ONR (award N00014-14-1-0805), the ARO and the PECASE program (award W911NF-14-1-0154), the AFOSR (award FA9550-12-1-0305), and the Alfred P. Sloan foundation (grant BR2013-110).

  9. Moving embedded lattice solitons.

    PubMed

    Malomed, B A; Fujioka, J; Espinosa-Cerón, A; Rodríguez, R F; González, S

    2006-03-01

    It was recently proved that solitons embedded in the spectrum of linear waves may exist in discrete systems, and explicit solutions for isolated unstable embedded lattice solitons (ELS) of a differential-difference version of a higher-order nonlinear Schrodinger equation were found [Gonzalez-Perez-Sandi, Fujioka, and Malomed, Physica D 197, 86 (2004)]. The discovery of these ELS gives rise to relevant questions such as the following: (1) Are there continuous families of ELS? (2) Can ELS be stable? (3) Is it possible for ELS to move along the lattice? (4) How do ELS interact? The present work addresses these questions by showing that a novel equation (a discrete version of a complex modified Korteweg-de Vries equation that includes next-nearest-neighbor couplings) has a two-parameter continuous family of exact ELS. These solitons can move with arbitrary velocities across the lattice, and the numerical simulations demonstrate that these ELS are completely stable. Moreover, the numerical tests show that these ELS are robust enough to withstand collisions, and the result of a collision is only a shift in the positions of the solitons. The model may apply to the description of a Bose-Einstein condensate with dipole-dipole interactions between the atoms, trapped in a deep optical-lattice potential.

  10. Career Ladders and Lattices.

    ERIC Educational Resources Information Center

    Dory, Fran

    1975-01-01

    The first part of this report discusses the career lattice concept in the Career Opportunities Program (COP), a concept which represents the marriage of two career development ideas--upward mobility and task differentiation at separate levels. It explains that by combining task differentiation and upward mobility, a system can effectively reduce a…

  11. Convex Lattice Polygons

    ERIC Educational Resources Information Center

    Scott, Paul

    2006-01-01

    A "convex" polygon is one with no re-entrant angles. Alternatively one can use the standard convexity definition, asserting that for any two points of the convex polygon, the line segment joining them is contained completely within the polygon. In this article, the author provides a solution to a problem involving convex lattice polygons.

  12. Progress in lattice QCD

    SciTech Connect

    Andreas S. Kronfeld

    2002-09-30

    After reviewing some of the mathematical foundations and numerical difficulties facing lattice QCD, I review the status of several calculations relevant to experimental high-energy physics. The topics considered are moments of structure functions, which may prove relevant to search for new phenomena at the LHC, and several aspects of flavor physics, which are relevant to understanding CP and flavor violation.

  13. Random lattice superstrings

    SciTech Connect

    Feng Haidong; Siegel, Warren

    2006-08-15

    We propose some new simplifying ingredients for Feynman diagrams that seem necessary for random lattice formulations of superstrings. In particular, half the fermionic variables appear only in particle loops (similarly to loop momenta), reducing the supersymmetry of the constituents of the type IIB superstring to N=1, as expected from their interpretation in the 1/N expansion as super Yang-Mills.

  14. Phenomenology Using Lattice QCD

    NASA Astrophysics Data System (ADS)

    Gupta, R.

    2005-08-01

    This talk provides a brief summary of the status of lattice QCD calculations of the light quark masses and the kaon bag parameter BK. Precise estimates of these four fundamental parameters of the standard model, i.e., mu, md, ms and the CP violating parameter η, help constrain grand unified models and could provide a window to new physics.

  15. Phenomenology Using Lattice QCD

    NASA Astrophysics Data System (ADS)

    Gupta, R.

    This talk provides a brief summary of the status of lattice QCD calculations of the light quark masses and the kaon bag parameter BK. Precise estimates of these four fundamental parameters of the standard model, i.e., mu, md, ms and the CP violating parameter η, help constrain grand unified models and could provide a window to new physics.

  16. Rigidity of lattice domes

    NASA Technical Reports Server (NTRS)

    Savelyev, V. A.

    1979-01-01

    The means of ensuring total rigidity of lattice domes, using comparison with solid shells of 1-3 layers are discussed. Irregularities of manufacture, processing, and other factors are considered, as they relate to diminution of rigidity. The discussion uses the concepts of upper and lower critical loads on the structure in question.

  17. Localization oscillation in antidot lattices

    NASA Astrophysics Data System (ADS)

    Uryu, S.; Ando, T.

    1998-06-01

    The Anderson localization in square and hexagonal antidot lattices is numerically studied with the use of a Thouless number method. It is revealed that localization is very sensitive to the aspect ratio between the antidot diameter and the lattice constant. In a hexagonal lattice, both the Thouless number and the localization length oscillate with the period equal to the Al’tshuler-Aronov-Spivak oscillation. The oscillation is quite weak in a square lattice.

  18. Rare B meson decays on the lattice

    NASA Astrophysics Data System (ADS)

    Agadjanov, Andria

    2017-03-01

    We discuss a framework for the measurement of the B → K* transition form factors in lattice simulations, when the K* eventually decays. The possible mixing of πK and ηK states is considered. We reproduce the two-channel analogue of the Lellouch-Lüscher formula, which allows one to extract the B → K*l+l- decay amplitude in the low-recoil region. Since the K* is a resonance, we provide a procedure to determine the form factors at the complex pole position in a process-independent manner. The infinitely-narrow width approximation of the results is also studied.

  19. A novel colorimetric and fluorescent probe for simultaneous detection of SO3(2-)/HSO3(-) and HSO4(-) by different emission channels and its bioimaging in living cells.

    PubMed

    Yu, Ting; Yin, Guoxing; Niu, Tingting; Yin, Peng; Li, Haitao; Zhang, Youyu; Chen, Haimin; Zeng, Ying; Yao, Shouzhuo

    2018-01-01

    A novel fluorescent probe (E)-3-ethyl-2-(4-hydroxystyryl)-1,1-di-methyl-1H-benzo-[e]indolium iodide (probe EDB) based on benzo[e]indolium was synthesized, which provided the simultaneous detection of SO3(2-)/HSO3(-) and HSO4(-) ion with different emission channels. Based on the principle of ion-induced rotation-displaced H-aggregates, when treated with NaHSO4, a fluorescence enhancement at 580nm was observed with the excitation wavelength at 420nm. While, in the advantage of the nucleophilic addition of SO3(2-) to the vinyl group, strong fluorescence was obtained at 455nm when treated with Na2SO3 with the excitation wavelength at 320nm, along with obvious color change by naked eyes. So the probe could be applied to sense SO3(2-)/HSO3(-) and HSO4(-) ion via different excited and emission channels simultaneously. The probe was also applicable for fluorescence imagings of bisulfite and hydrosulfate in HeLa cells. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Biological Lattice Gas Models

    NASA Astrophysics Data System (ADS)

    Alber, Mark S.; Kiskowski, Maria; Jiang, Yi; Newman, Stuart

    Modelling pattern formation and morphogenesis are fundamental problems in biology. One useful approach is lattice gas cellular automata (LGCA) model. This paper reviews several stochastic lattice gas models for pattern formation in myxobacteria fruiting body morphogenesis and vertebrate limb skeletogenesis. The fruiting body formation in myxobacteria is a complex morphological process that requires the organized, collective effort of tens of thousands of cells. It provides new insight into collective microbial behavior since myxobacteria morphogenic pattern formation is governed by cell-cell interactions rather than chemotaxis. We describe LGCA models for the aggregation stage of the fruiting body formation. Limb bud precartilage mesenchymal cells in micromass culture undergo chondrogenic pattern formation, which results in the formation of regularly-spaced "islands" of cartilage analogous to the cartilage primordia of the developing limb skeleton. An LGCA model, based on reaction-diffusion coupling and cell-matrix adhesion, is described for this process.

  1. Statistics of lattice animals

    NASA Astrophysics Data System (ADS)

    Hsu, Hsiao-Ping; Nadler, Walder; Grassberger, Peter

    2005-07-01

    The scaling behavior of randomly branched polymers in a good solvent is studied in two to nine dimensions, modeled by lattice animals on simple hypercubic lattices. For the simulations, we use a biased sequential sampling algorithm with re-sampling, similar to the pruned-enriched Rosenbluth method (PERM) used extensively for linear polymers. We obtain high statistics of animals with up to several thousand sites in all dimension 2⩽d⩽9. The partition sum (number of different animals) and gyration radii are estimated. In all dimensions we verify the Parisi-Sourlas prediction, and we verify all exactly known critical exponents in dimensions 2, 3, 4, and ⩾8. In addition, we present the hitherto most precise estimates for growth constants in d⩾3. For clusters with one site attached to an attractive surface, we verify the superuniversality of the cross-over exponent at the adsorption transition predicted by Janssen and Lyssy.

  2. Parametric lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Shim, Jae Wan

    2017-06-01

    The discretized equilibrium distributions of the lattice Boltzmann method are presented by using the coefficients of the Lagrange interpolating polynomials that pass through the points related to discrete velocities and using moments of the Maxwell-Boltzmann distribution. The ranges of flow velocity and temperature providing positive valued distributions vary with regulating discrete velocities as parameters. New isothermal and thermal compressible models are proposed for flows of the level of the isothermal and thermal compressible Navier-Stokes equations. Thermal compressible shock tube flows are simulated by only five on-lattice discrete velocities. Two-dimensional isothermal and thermal vortices provoked by the Kelvin-Helmholtz instability are simulated by the parametric models.

  3. Fractional lattice charge transport

    PubMed Central

    Flach, Sergej; Khomeriki, Ramaz

    2017-01-01

    We consider the dynamics of noninteracting quantum particles on a square lattice in the presence of a magnetic flux α and a dc electric field E oriented along the lattice diagonal. In general, the adiabatic dynamics will be characterized by Bloch oscillations in the electrical field direction and dispersive ballistic transport in the perpendicular direction. For rational values of α and a corresponding discrete set of values of E(α) vanishing gaps in the spectrum induce a fractionalization of the charge in the perpendicular direction - while left movers are still performing dispersive ballistic transport, the complementary fraction of right movers is propagating in a dispersionless relativistic manner in the opposite direction. Generalizations and the possible probing of the effect with atomic Bose-Einstein condensates and photonic networks are discussed. Zak phase of respective band associated with gap closing regime has been computed and it is found converging to π/2 value. PMID:28102302

  4. Introduction to lattice QCD

    SciTech Connect

    Gupta, R.

    1998-12-31

    The goal of the lectures on lattice QCD (LQCD) is to provide an overview of both the technical issues and the progress made so far in obtaining phenomenologically useful numbers. The lectures consist of three parts. The author`s charter is to provide an introduction to LQCD and outline the scope of LQCD calculations. In the second set of lectures, Guido Martinelli will discuss the progress they have made so far in obtaining results, and their impact on Standard Model phenomenology. Finally, Martin Luescher will discuss the topical subjects of chiral symmetry, improved formulation of lattice QCD, and the impact these improvements will have on the quality of results expected from the next generation of simulations.

  5. Instantons on the lattice

    NASA Astrophysics Data System (ADS)

    Fucito, F.; Solomon, S.

    By modifying the lattice action of spin and gauge models we insure that the system cannot tunnel between topological sectors by local Monte Carlo (MC) steps. We insure the correct weight of the topological sectors in the statistical sum by considering global MC steps. This strategy permits us to study the effects of topological objects in ϑ-vacua, < Q2> scaling and chiral symmetry breaking in a straightforward way.

  6. Charmonium from Lattice QCD

    SciTech Connect

    Jozef Dudek

    2007-08-05

    Charmonium is an attractive system for the application of lattice QCD methods. While the sub-threshold spectrum has been considered in some detail in previous works, it is only very recently that excited and higher-spin states and further properties such as radiative transitions and two-photon decays have come to be calculated. I report on this recent progress with reference to work done at Jefferson Lab.

  7. Multipole plasmonic lattice solitons

    SciTech Connect

    Kou Yao; Ye Fangwei; Chen Xianfeng

    2011-09-15

    We theoretically demonstrate a variety of multipole plasmonic lattice solitons, including dipoles, quadrupoles, and necklaces, in two-dimensional metallic nanowire arrays with Kerr-type nonlinearities. Such solitons feature complex internal structures with an ultracompact mode size approaching or smaller than one wavelength. Their mode sizes and the stability characteristics are studied in detail within the framework of coupled mode theory. The conditions to form and stabilize these highly confined solitons are within the experimentally achievable range.

  8. Lattice dynamics of coesite.

    PubMed

    Wehinger, Björn; Bosak, Alexeï; Chumakov, Aleksandr; Mirone, Alessandro; Winkler, Björn; Dubrovinsky, Leonid; Dubrovinskaia, Natalia; Brazhkin, Vadim; Dyuzheva, Tatiana; Krisch, Michael

    2013-07-10

    The lattice dynamics of coesite has been studied by a combination of diffuse x-ray scattering, inelastic x-ray scattering and ab initio lattice dynamics calculations. The combined technique gives access to the full lattice dynamics in the harmonic description and thus eventually provides detailed information on the elastic properties, the stability and metastability of crystalline systems. The experimentally validated calculation was used for the investigation of the eigenvectors, mode character and their contribution to the density of vibrational states. High-symmetry sections of the reciprocal space distribution of diffuse scattering and inelastic x-ray scattering spectra as well as the density of vibrational states and the dispersion relation are reported and compared to the calculation. A critical point at the zone boundary is found to contribute strongly to the main peak of the low-energy part in the density of vibrational states. Comparison with the most abundant SiO2 polymorph--α-quartz--reveals similarities and distinct differences in the low-energy vibrational properties.

  9. Digital lattice gauge theories

    NASA Astrophysics Data System (ADS)

    Zohar, Erez; Farace, Alessandro; Reznik, Benni; Cirac, J. Ignacio

    2017-02-01

    We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with 2 +1 dimensions and higher are obtained stroboscopically, through a sequence of two-body interactions with ancillary degrees of freedom. This yields stronger interactions than the ones obtained through perturbative methods, as typically done in previous proposals, and removes an important bottleneck in the road towards experimental realizations. The scheme applies to generic gauge theories with Lie or finite symmetry groups, both Abelian and non-Abelian. As a concrete example, we present the construction of a digital quantum simulator for a Z3 lattice gauge theory with dynamical fermionic matter in 2 +1 dimensions, using ultracold atoms in optical lattices, involving three atomic species, representing the matter, gauge, and auxiliary degrees of freedom, that are separated in three different layers. By moving the ancilla atoms with a proper sequence of steps, we show how we can obtain the desired evolution in a clean, controlled way.

  10. Crystallographic Lattice Boltzmann Method

    NASA Astrophysics Data System (ADS)

    Namburi, Manjusha; Krithivasan, Siddharth; Ansumali, Santosh

    2016-06-01

    Current approaches to Direct Numerical Simulation (DNS) are computationally quite expensive for most realistic scientific and engineering applications of Fluid Dynamics such as automobiles or atmospheric flows. The Lattice Boltzmann Method (LBM), with its simplified kinetic descriptions, has emerged as an important tool for simulating hydrodynamics. In a heterogeneous computing environment, it is often preferred due to its flexibility and better parallel scaling. However, direct simulation of realistic applications, without the use of turbulence models, remains a distant dream even with highly efficient methods such as LBM. In LBM, a fictitious lattice with suitable isotropy in the velocity space is considered to recover Navier-Stokes hydrodynamics in macroscopic limit. The same lattice is mapped onto a cartesian grid for spatial discretization of the kinetic equation. In this paper, we present an inverted argument of the LBM, by making spatial discretization as the central theme. We argue that the optimal spatial discretization for LBM is a Body Centered Cubic (BCC) arrangement of grid points. We illustrate an order-of-magnitude gain in efficiency for LBM and thus a significant progress towards feasibility of DNS for realistic flows.

  11. Topological lattice actions

    NASA Astrophysics Data System (ADS)

    Bietenholz, W.; Gerber, U.; Pepe, M.; Wiese, U.-J.

    2010-12-01

    We consider lattice field theories with topological actions, which are invariant against small deformations of the fields. Some of these actions have infinite barriers separating different topological sectors. Topological actions do not have the correct classical continuum limit and they cannot be treated using perturbation theory, but they still yield the correct quantum continuum limit. To show this, we present analytic studies of the 1-d O(2) and O(3) model, as well as Monte Carlo simulations of the 2-d O(3) model using topological lattice actions. Some topological actions obey and others violate a lattice Schwarz inequality between the action and the topological charge Q. Irrespective of this, in the 2-d O(3) model the topological susceptibility {χ_t} = {{{left< {{Q^2}} rightrangle }} left/ {V} right.} is logarithmically divergent in the continuum limit. Still, at non-zero distance the correlator of the topological charge density has a finite continuum limit which is consistent with analytic predictions. Our study shows explicitly that some classically important features of an action are irrelevant for reaching the correct quantum continuum limit.

  12. Hadroquarkonium from lattice QCD

    NASA Astrophysics Data System (ADS)

    Alberti, Maurizio; Bali, Gunnar S.; Collins, Sara; Knechtli, Francesco; Moir, Graham; Söldner, Wolfgang

    2017-04-01

    The hadroquarkonium picture [S. Dubynskiy and M. B. Voloshin, Phys. Lett. B 666, 344 (2008), 10.1016/j.physletb.2008.07.086] provides one possible interpretation for the pentaquark candidates with hidden charm, recently reported by the LHCb Collaboration, as well as for some of the charmoniumlike "X , Y , Z " states. In this picture, a heavy quarkonium core resides within a light hadron giving rise to four- or five-quark/antiquark bound states. We test this scenario in the heavy quark limit by investigating the modification of the potential between a static quark-antiquark pair induced by the presence of a hadron. Our lattice QCD simulations are performed on a Coordinated Lattice Simulations (CLS) ensemble with Nf=2 +1 flavors of nonperturbatively improved Wilson quarks at a pion mass of about 223 MeV and a lattice spacing of about a =0.0854 fm . We study the static potential in the presence of a variety of light mesons as well as of octet and decuplet baryons. In all these cases, the resulting configurations are favored energetically. The associated binding energies between the quarkonium in the heavy quark limit and the light hadron are found to be smaller than a few MeV, similar in strength to deuterium binding. It needs to be seen if the small attraction survives in the infinite volume limit and supports bound states or resonances.

  13. Crystallographic Lattice Boltzmann Method

    PubMed Central

    Namburi, Manjusha; Krithivasan, Siddharth; Ansumali, Santosh

    2016-01-01

    Current approaches to Direct Numerical Simulation (DNS) are computationally quite expensive for most realistic scientific and engineering applications of Fluid Dynamics such as automobiles or atmospheric flows. The Lattice Boltzmann Method (LBM), with its simplified kinetic descriptions, has emerged as an important tool for simulating hydrodynamics. In a heterogeneous computing environment, it is often preferred due to its flexibility and better parallel scaling. However, direct simulation of realistic applications, without the use of turbulence models, remains a distant dream even with highly efficient methods such as LBM. In LBM, a fictitious lattice with suitable isotropy in the velocity space is considered to recover Navier-Stokes hydrodynamics in macroscopic limit. The same lattice is mapped onto a cartesian grid for spatial discretization of the kinetic equation. In this paper, we present an inverted argument of the LBM, by making spatial discretization as the central theme. We argue that the optimal spatial discretization for LBM is a Body Centered Cubic (BCC) arrangement of grid points. We illustrate an order-of-magnitude gain in efficiency for LBM and thus a significant progress towards feasibility of DNS for realistic flows. PMID:27251098

  14. Lattice location of implanted transition metals in 3C-SiC

    NASA Astrophysics Data System (ADS)

    Costa, A. R. G.; Wahl, U.; Correia, J. G.; Bosne, E.; Amorim, L. M.; Augustyns, V.; Silva, D. J.; da Silva, M. R.; Bharuth-Ram, K.; Pereira, L. M. C.

    2017-06-01

    We have investigated the lattice location of implanted transition metal (TM) 56Mn, 59Fe and 65Ni ions in undoped single-crystalline cubic 3C-SiC by means of the emission channeling technique using radioactive isotopes produced at the CERN-ISOLDE facility. We find that in the room temperature as-implanted state, most Mn, Fe and Ni atoms occupy carbon-coordinated tetrahedral interstitial sites (T C). Smaller TM fractions were also found on Si substitutional (S Si) sites. The TM atoms partially disappear from ideal-T C positions during annealing at temperatures between 500 °C and 700 °C, which is accompanied by an increase in the TM fraction occupying both S Si sites and random sites. An explanation is given according to what is known about the annealing mechanisms of silicon vacancies in silicon carbide. The origin of the observed lattice sites and their changes with thermal annealing are discussed and compared to the case of Si, highlighting the feature that the interstitial migration of TMs in SiC is much slower than in Si.

  15. Entropic Lattice Boltzmann Methods for Fluid Mechanics

    NASA Astrophysics Data System (ADS)

    Chikatamarla, Shyam; Boesch, Fabian; Sichau, David; Karlin, Ilya

    2013-11-01

    With its roots in statistical mechanics and kinetic theory, the lattice Boltzmann method (LBM) is a paradigm-changing innovation, offering for the first time an intrinsically parallel CFD algorithm. Over the past two decades, LBM has achieved numerous results in the field of CFD and is now in a position to challenge state-of-the art CFD techniques. Our major restyling of LBM resulted in an unconditionally stable entropic LBM which restored Second Law (Boltzmann H theorem) in the LBM kinetics and thus enabled affordable direct simulations of fluid turbulence. We review here recent advances in ELBM as a practical, modeling-free tool for simulation of turbulent flows in complex geometries. We shall present recent simulations including turbulent channel flow, flow past a circular cylinder, knotted vortex tubes, and flow past a surface mounted cube. ELBM listed all admissible lattices supporting a discrete entropy function and has classified them in hierarchically increasing order of accuracy. Applications of these higher-order lattices to simulations of turbulence and thermal flows shall also be presented. This work was supported CSCS grant s437.

  16. Ultracold Nonreactive Molecules in an Optical Lattice: Connecting Chemistry to Many-Body Physics.

    PubMed

    Doçaj, Andris; Wall, Michael L; Mukherjee, Rick; Hazzard, Kaden R A

    2016-04-01

    We derive effective lattice models for ultracold bosonic or fermionic nonreactive molecules (NRMs) in an optical lattice, analogous to the Hubbard model that describes ultracold atoms in a lattice. In stark contrast to the Hubbard model, which is commonly assumed to accurately describe NRMs, we find that the single on-site interaction parameter U is replaced by a multichannel interaction, whose properties we elucidate. Because this arises from complex short-range collisional physics, it requires no dipolar interactions and thus occurs even in the absence of an electric field or for homonuclear molecules. We find a crossover between coherent few-channel models and fully incoherent single-channel models as the lattice depth is increased. We show that the effective model parameters can be determined in lattice modulation experiments, which, consequently, measure molecular collision dynamics with a vastly sharper energy resolution than experiments in a free-space ultracold gas.

  17. Lattice-induced nonadiabatic frequency shifts in optical lattice clocks

    SciTech Connect

    Beloy, K.

    2010-09-15

    We consider the frequency shift in optical lattice clocks which arises from the coupling of the electronic motion to the atomic motion within the lattice. For the simplest of three-dimensional lattice geometries this coupling is shown to affect only clocks based on blue-detuned lattices. We have estimated the size of this shift for the prospective strontium lattice clock operating at the 390-nm blue-detuned magic wavelength. The resulting fractional frequency shift is found to be on the order of 10{sup -18} and is largely overshadowed by the electric quadrupole shift. For lattice clocks based on more complex geometries or other atomic systems, this shift could potentially be a limiting factor in clock accuracy.

  18. Lattice topology dictates photon statistics.

    PubMed

    Kondakci, H Esat; Abouraddy, Ayman F; Saleh, Bahaa E A

    2017-08-21

    Propagation of coherent light through a disordered network is accompanied by randomization and possible conversion into thermal light. Here, we show that network topology plays a decisive role in determining the statistics of the emerging field if the underlying lattice is endowed with chiral symmetry. In such lattices, eigenmode pairs come in skew-symmetric pairs with oppositely signed eigenvalues. By examining one-dimensional arrays of randomly coupled waveguides arranged on linear and ring topologies, we are led to a remarkable prediction: the field circularity and the photon statistics in ring lattices are dictated by its parity while the same quantities are insensitive to the parity of a linear lattice. For a ring lattice, adding or subtracting a single lattice site can switch the photon statistics from super-thermal to sub-thermal, or vice versa. This behavior is understood by examining the real and imaginary fields on a lattice exhibiting chiral symmetry, which form two strands that interleave along the lattice sites. These strands can be fully braided around an even-sited ring lattice thereby producing super-thermal photon statistics, while an odd-sited lattice is incommensurate with such an arrangement and the statistics become sub-thermal.

  19. Single identities for lattice theory and for weakly associative lattices

    SciTech Connect

    McCune, W.; Padmanabhan, R.

    1995-03-13

    We present a single identity for the variety of all lattices that is much simpler than those previously known to us. We also show that the variety of weakly associative lattices is one-based, and we present a generalized one-based theorem for subvarieties of weakly associative lattices that can be defined with absorption laws. The automated theorem-proving program OTTER was used in substantial way to obtain the results.

  20. Searching for X (3872) using lattice QCD

    NASA Astrophysics Data System (ADS)

    Lee, Song-Haeng; Detar, Carleton; MILC / Fermilab Collaboration

    2016-03-01

    For decades, many excited charmonium states have been discovered that cannot be explained within the conventional quark model. Among the those mesons, the narrow charmonium-like state X (3872) has been examined using various phenomenological models, however, the question for its constituent still remains open. One of the strong candidates is a DD* molecular state because its mass is within 1MeV of the DD* threshold, however, such a molecular state can't be directly studied by perturbative QCD in such a low energy regime where the interaction of the colored quarks and gluons is very strong. Numerical simulation with lattice QCD provides a nonperturbative, ab initio method for studying this mysterious meson state. In this talk, I present preliminary simulation results for this charmonium-like states with quantum numbers JPC =1++ in both the isospin 0 and 1 channels. We use interpolating operators including both the conventional excited P-wave charmonium state (χc 1) and the DD* open charm state for the isospin 0 channel, but only DD* for the isospin 1 channel. We extract large negative S-wave scattering length and find an X (3872) candidate 13 +/- 6 MeV below the DD* threshold in the isospin 0 channel.

  1. Lattice thermal conductivity of minerals in the deep mantle condition

    NASA Astrophysics Data System (ADS)

    Dekura, H.; Tsuchiya, T.; Tsuchiya, J.

    2011-12-01

    Thermal transport property of materials under pressure and temperature is of importance for understanding the dynamics of the solid Earth and the thermal history. Both experimental and theoretical determinations of the thermal conductivity, however, still remain technically challenging particularly at the deep mantle condition. Recent progress in ab initio computational method based on the density-functional theory is now makes it possible to examine the transport phenomena including the lattice thermal conduction. The intrinsic bulk thermal conduction of insulator is caused by lattice anharmonicity owing to phonon-phonon interaction. The key parameter to predict lattice thermal conductivity is thus the anharmonic coupling constant. Earlier theoretical works calculated the lattice thermal conductivity of MgO with ab initio molecular dynamics simulation or finite difference lattice dynamics simulation (Nico de Koker, Phys. Rev. Lett. 103, 125902, 2009; X. Tang and J. Dong, Proc. Natl. Acad. Sci. U.S.A. 107, 4539, 2010). However, in these approaches, the simulation cell size could often be insufficient for accurate description of the long wavelength phonon scattering. This leads to a lack of the decay channels for the phonons. As an alternative approach, the anharmonic coupling strength between phonon modes can be evaluated within the density-functional perturbation theory. In this approach, the higher-order force tensors are calculated through a number of phonon decay channels obtained within the perturbative scheme taking care only of the primitive cell. We have been developing a technique for calculation of the phonon linewidth necessary to obtain the phonon lifetime. Then the lattice thermal conductivity is evaluated combining with additional harmonic-level of propeties. In this presentation, we show the behavior of lattice thermal conductivity in lower mantle minerals, and discuss the effects of pressure and temperature on their conductivities up to the deep

  2. Thermodynamics of the Relationship between Lattice Energy and Lattice Enthalpy

    NASA Astrophysics Data System (ADS)

    Jenkins, H. Donald B.

    2005-06-01

    Incorporation of lattice potential energy, U POT , within a Born Fajans Haber thermochemical cycle based on enthalpy changes necessitates correction of the energy of the lattice to an enthalpy term, Δ H L . For a lattice containing p i ions of type i in the formula unit, the lattice enthalpy is given by Δ H L = U POT + ∑ s i [( c i /2) - 2] RT where R is the gas constant (= 8.314 J K -1 mol -1 ), T is the absolute temperature, and c i is defined according as to whether the ion i is monatomic ( c i = 3), linear polyatomic ( c i = 5), or polyatomic ( c i = 6), respectively.

  3. Group theoretical construction of extended baryon operators in lattice QCD

    SciTech Connect

    Subhasish Basak; Robert Edwards; George Fleming; Urs Heller; Colin Morningstar; David Richards; Ikuro Sato; Stephen Wallace

    2005-06-01

    The design and implementation of large sets of spatially-extended, gauge-invariant operators for use in determining the spectrum of baryons in lattice QCD computations are described. Group theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. The operators are constructed to maximize overlaps with the low-lying states of interest, while minimizing the number of sources needed in computing the required quark propagators. Issues related to the identification of the spin quantum numbers of the states in the continuum limit are addressed.

  4. Lattice Boltzmann Method for Two-Dimensional Unsteady Incompressible Flow

    NASA Astrophysics Data System (ADS)

    Mužík, Juraj

    2016-12-01

    A Lattice Boltzmann method is used to analyse incompressible fluid flow in a two-dimensional cavity and flow in the channel past cylindrical obstacle. The method solves the Boltzmann's transport equation using simple computational grid - lattice. With the proper choice of the collision operator, the Boltzmann's equation can be converted into incompressible Navier-Stokes equation. Lid-driven cavity benchmark case for various Reynolds numbers and flow past cylinder is presented in the article. The method produces stable solutions with results comparable to those in literature and is very easy to implement.

  5. Full lattice QCD study of the κ scalar meson

    NASA Astrophysics Data System (ADS)

    Fu, Zi-Wen; Carleton, DeTar

    2011-12-01

    We studied the κ light scalar meson in 2+1 flavor full QCD with sufficiently light u and d quarks. Via lattice simulation we measured the correlators for the κ channel in the “Asqtad" improved staggered fermion formulation. After chiral extrapolation we obtained the mass of the κ meson with 826 ± 119 MeV, which is within recent experimental values of 800-900 MeV. The simulations were carried out with the MILC 2+1 flavor gauge configurations at lattice spacing a≈0.15 fm.

  6. Lattice QCD for nuclei

    NASA Astrophysics Data System (ADS)

    Beane, Silas

    2016-09-01

    Over the last several decades, theoretical nuclear physics has been evolving from a very-successful phenomenology of the properties of nuclei, to a first-principles derivation of the properties of visible matter in the Universe from the known underlying theories of Quantum Chromodynamics (QCD) and Electrodynamics. Many nuclear properties have now been calculated using lattice QCD, a method for treating QCD numerically with large computers. In this talk, some of the most recent results in this frontier area of nuclear theory will be reviewed.

  7. Thermodynamics of lattice OCD

    SciTech Connect

    Matsuoka, H.

    1985-01-01

    The thermodynamic consequences of QCD are explored in the framework of lattice gauge theory. Attention is focused upon the nature of the chiral symmetry restoration transition at finite temperature and at finite baryon density, and possible strategies for identifying relevant thermodynamic phases are discussed. Some numerical results are presented on the chiral symmetry restoration in the SU(2) gauge theory at high baryon density. The results suggest that with T approx. = 110 MeV there is a second order restoration transition at the critical baryon density n/sub B//sup c/ approx. = 0.62 fm/sup -3/.

  8. Lava Channels

    NASA Image and Video Library

    2013-12-03

    The channels and linear depression in this image captured by NASA 2001 Mars Odyssey spacecraft are located on the western margin of the Elysium Volcanic complex. The channels were created by lava flow.

  9. Achromatic Cooling Channel with Li Lenses

    SciTech Connect

    Balbekov, V.

    2002-04-29

    A linear cooling channel with Li lenses, solenoids, and 201 MHz RF cavities is considered. A special lattice design is used to minimize chromatic aberrations by suppression of several betatron resonances. Transverse emittance of muon beam decreases from 2 mm to 0.5 mm at the channel of about 110 m length. Longitudinal heating is modest, therefore transmission of the channel is rather high: 96% without decay and 90% with decay. Minimal beam emittance achievable by similar channel estimated as about 0.25 mm at surface field of Li lenses 10 T.

  10. Lattice harmonics expansion revisited

    NASA Astrophysics Data System (ADS)

    Kontrym-Sznajd, G.; Holas, A.

    2017-04-01

    The main subject of the work is to provide the most effective way of determining the expansion of some quantities into orthogonal polynomials, when these quantities are known only along some limited number of sampling directions. By comparing the commonly used Houston method with the method based on the orthogonality relation, some relationships, which define the applicability and correctness of these methods, are demonstrated. They are verified for various sets of sampling directions applicable for expanding quantities having the full symmetry of the Brillouin zone of cubic and non-cubic lattices. All results clearly show that the Houston method is always better than the orthogonality-relation one. For the cubic symmetry we present a few sets of special directions (SDs) showing how their construction and, next, a proper application depend on the choice of various sets of lattice harmonics. SDs are important mainly for experimentalists who want to reconstruct anisotropic quantities from their measurements, performed at a limited number of sampling directions.

  11. Lattice Transparency of Graphene.

    PubMed

    Chae, Sieun; Jang, Seunghun; Choi, Won Jin; Kim, Youn Sang; Chang, Hyunju; Lee, Tae Il; Lee, Jeong-O

    2017-03-08

    Here, we demonstrated the transparency of graphene to the atomic arrangement of a substrate surface, i.e., the "lattice transparency" of graphene, by using hydrothermally grown ZnO nanorods as a model system. The growth behaviors of ZnO nanocrystals on graphene-coated and uncoated substrates with various crystal structures were investigated. The atomic arrangements of the nucleating ZnO nanocrystals exhibited a close match with those of the respective substrates despite the substrates being bound to the other side of the graphene. By using first-principles calculations based on density functional theory, we confirmed the energetic favorability of the nucleating phase following the atomic arrangement of the substrate even with the graphene layer present in between. In addition to transmitting information about the atomic lattice of the substrate, graphene also protected its surface. This dual role enabled the hydrothermal growth of ZnO nanorods on a Cu substrate, which otherwise dissolved in the reaction conditions when graphene was absent.

  12. Orthocomplemented complete lattices and graphs

    NASA Astrophysics Data System (ADS)

    Ollech, Astrid

    1995-08-01

    The problem I consider originates from Dörfler, who found a construction to assign an Orthocomplemented lattice H(G) to a graph G. By Dörfler it is known that for every finite Orthocomplemented lattice L there exists a graph G such that H(G)=L. Unfortunately, we can find more than one graph G with this property, i.e., orthocomplemented lattices which belong to different graphs can be isomorphic. I show some conditions under which two graphs have the same orthocomplemented lattice.

  13. Extreme lattices: symmetries and decorrelation

    NASA Astrophysics Data System (ADS)

    Andreanov, A.; Scardicchio, A.; Torquato, S.

    2016-11-01

    We study statistical and structural properties of extreme lattices, which are the local minima in the density landscape of lattice sphere packings in d-dimensional Euclidean space {{{R}}d} . Specifically, we ascertain statistics of the densities and kissing numbers as well as the numbers of distinct symmetries of the packings for dimensions 8 through 13 using the stochastic Voronoi algorithm. The extreme lattices in a fixed dimension of space d (d≥slant 8 ) are dominated by typical lattices that have similar packing properties, such as packing densities and kissing numbers, while the best and the worst packers are in the long tails of the distribution of the extreme lattices. We also study the validity of the recently proposed decorrelation principle, which has important implications for sphere packings in general. The degree to which extreme-lattice packings decorrelate as well as how decorrelation is related to the packing density and symmetry of the lattices as the space dimension increases is also investigated. We find that the extreme lattices decorrelate with increasing dimension, while the least symmetric lattices decorrelate faster.

  14. More on lattice BRST invariance

    NASA Astrophysics Data System (ADS)

    Bock, Wolfgang; Golterman, Maarten F. L.; Shamir, Yigal

    1998-11-01

    In the gauge-fixing approach to (chiral) lattice gauge theories, the action in the U(1) case implicitly contains a free ghost term, in accordance with the continuum Abelian theory. On the lattice there is no BRST symmetry and, without fermions, the partition function is strictly positive. Recently, Neuberger pointed out, Phys. Rev. D 58, 057502 (1998), that a different choice of the ghost term would lead to a BRST-invariant lattice model, which is ill defined nonperturbatively. We show that such a lattice model is inconsistent already in perturbation theory, and clearly different from the gauge-fixing approach.

  15. Nuclear Physics and Lattice QCD

    SciTech Connect

    Beane, Silas

    2003-11-01

    Impressive progress is currently being made in computing properties and interac- tions of the low-lying hadrons using lattice QCD. However, cost limitations will, for the foreseeable future, necessitate the use of quark masses, Mq, that are signif- icantly larger than those of nature, lattice spacings, a, that are not significantly smaller than the physical scale of interest, and lattice sizes, L, that are not sig- nificantly larger than the physical scale of interest. Extrapolations in the quark masses, lattice spacing and lattice volume are therefore required. The hierarchy of mass scales is: L 1 j Mq j â ºC j a 1 . The appropriate EFT for incorporating the light quark masses, the finite lattice spacing and the lattice size into hadronic observables is C-PT, which provides systematic expansions in the small parame- ters e m L, 1/ Lâ ºC, p/â ºC, Mq/â ºC and aâ ºC . The lattice introduces other unphysical scales as well. Lattice QCD quarks will increasingly be artificially separated

  16. Two Nucleons on a Lattice

    SciTech Connect

    S.R. Beane; P.F.Bedaque; A. Parreno; M.J. Savage

    2004-04-01

    The two-nucleon sector is near an infrared fixed point of QCD and as a result the S-wave scattering lengths are unnaturally large compared to the effective ranges and shape parameters. It is usually assumed that a lattice QCD simulation of the two-nucleon sector will require a lattice that is much larger than the scattering lengths in order to extract quantitative information. In this paper we point out that this does not have to be the case: lattice QCD simulations on much smaller lattices will produce rigorous results for nuclear physics.

  17. Elimination of spurious lattice fermion solutions and noncompact lattice QCD

    SciTech Connect

    Lee, T.D.

    1997-09-22

    It is well known that the Dirac equation on a discrete hyper-cubic lattice in D dimension has 2{sup D} degenerate solutions. The usual method of removing these spurious solutions encounters difficulties with chiral symmetry when the lattice spacing l {ne} 0, as exemplified by the persistent problem of the pion mass. On the other hand, we recall that in any crystal in nature, all the electrons do move in a lattice and satisfy the Dirac equation; yet there is not a single physical result that has ever been entangled with a spurious fermion solution. Therefore it should not be difficult to eliminate these unphysical elements. On a discrete lattice, particle hop from point to point, whereas in a real crystal the lattice structure in embedded in a continuum and electrons move continuously from lattice cell to lattice cell. In a discrete system, the lattice functions are defined only on individual points (or links as in the case of gauge fields). However, in a crystal the electron state vector is represented by the Bloch wave functions which are continuous functions in {rvec {gamma}}, and herein lies one of the essential differences.

  18. Effect of AlN content on the lattice site location of terbium ions in Al x Ga1-x N compounds

    NASA Astrophysics Data System (ADS)

    Fialho, M.; Rodrigues, J.; Magalhães, S.; Correia, M. R.; Monteiro, T.; Lorenz, K.; Alves, E.

    2016-03-01

    Terbium lattice site location and optical emission in Tb implanted Al x Ga1-x N (0 ≤ x ≤ 1) samples grown by halide vapour phase epitaxy on (0001) sapphire substrates are investigated as a function of AlN content. The samples were implanted with a fluence of 5 × 1014 cm-2 of terbium ions and an energy of 150 keV. Lattice implantation damage is reduced using channelled ion implantation performed along the <0001> axis, normal to the sample surface. Afterwards, thermal annealing treatments at 1400 °C for GaN and 1200 °C for samples with x > 0 were performed to reduce the damage and to activate the optical emission of Tb3+ ions. The study of lattice site location is achieved measuring detailed angular ion channelling scans across the <0001>, < 10\\bar{1}1> and < \\bar{2}113> axial directions. The precise location of the implanted Tb ions is obtained by combining the information of these angular scans with simulations using the Monte Carlo code FLUX. In addition to a Ga/Al substitutional fraction and a random fraction, a fraction of Tb ions occupying a site displaced by 0.2 Å along c-axis from the Ga/Al substitutional site was considered, giving a good agreement between the experimental results and the simulation. Photoluminescence studies proved the optical activation of Tb3+ after thermal annealing and the enhancement of the 5D4 to 7F6 transition intensity with increasing AlN content.

  19. Optical Abelian lattice gauge theories

    SciTech Connect

    Tagliacozzo, L.; Celi, A.; Zamora, A.; Lewenstein, M.

    2013-03-15

    We discuss a general framework for the realization of a family of Abelian lattice gauge theories, i.e., link models or gauge magnets, in optical lattices. We analyze the properties of these models that make them suitable for quantum simulations. Within this class, we study in detail the phases of a U(1)-invariant lattice gauge theory in 2+1 dimensions, originally proposed by P. Orland. By using exact diagonalization, we extract the low-energy states for small lattices, up to 4 Multiplication-Sign 4. We confirm that the model has two phases, with the confined entangled one characterized by strings wrapping around the whole lattice. We explain how to study larger lattices by using either tensor network techniques or digital quantum simulations with Rydberg atoms loaded in optical lattices, where we discuss in detail a protocol for the preparation of the ground-state. We propose two key experimental tests that can be used as smoking gun of the proper implementation of a gauge theory in optical lattices. These tests consist in verifying the absence of spontaneous (gauge) symmetry breaking of the ground-state and the presence of charge confinement. We also comment on the relation between standard compact U(1) lattice gauge theory and the model considered in this paper. - Highlights: Black-Right-Pointing-Pointer We study the quantum simulation of dynamical gauge theories in optical lattices. Black-Right-Pointing-Pointer We focus on digital simulation of abelian lattice gauge theory. Black-Right-Pointing-Pointer We rediscover and discuss the puzzling phase diagram of gauge magnets. Black-Right-Pointing-Pointer We detail the protocol for time evolution and ground-state preparation in any phase. Black-Right-Pointing-Pointer We provide two experimental tests to validate gauge theory quantum simulators.

  20. TRP Channels

    PubMed Central

    Venkatachalam, Kartik; Montell, Craig

    2011-01-01

    The TRP (Transient Receptor Potential) superfamily of cation channels is remarkable in that it displays greater diversity in activation mechanisms and selectivities than any other group of ion channels. The domain organizations of some TRP proteins are also unusual, as they consist of linked channel and enzyme domains. A unifying theme in this group is that TRP proteins play critical roles in sensory physiology, which include contributions to vision, taste, olfaction, hearing, touch, and thermo- and osmosensation. In addition, TRP channels enable individual cells to sense changes in their local environment. Many TRP channels are activated by a variety of different stimuli and function as signal integrators. The TRP superfamily is divided into seven subfamilies: the five group 1 TRPs (TRPC, TRPV, TRPM, TRPN, and TRPA) and two group 2 subfamilies (TRPP and TRPML). TRP channels are important for human health as mutations in at least four TRP channels underlie disease. PMID:17579562

  1. Compromised extinction and signal-to-noise ratios of weak-resonant-cavity laser diode transmitter injected by channelized and amplitude squeezed spontaneous-emission.

    PubMed

    Lin, Yi-Hung; Lin, Gong-Cheng; Wang, Hai-Lin; Chi, Yu-Chieh; Lin, Gong-Ru

    2010-03-01

    By using a 200GHz AWG channelized ASE source in connection with a saturable semiconductor optical amplifier (SOA) based noise blocker as the injecting source at the remote node in front of the local optical network units (ONUs), we demonstrate the spectrum-sliced ASE transmitter with greatly suppressed intensity noise performance in WDM-PON network. Such channelized SOA filtering technique effectively reduces the relative intensity noise of the ASE source by at least 4.5 dB. The low-noise WRC-FPLD transmitter improves its extinction-ratio (ER) from 8.9 to 9.6 dB and signal-to-noise ratio (SNR) from 5.9 to 6.3 dB. In comparison with broad-band ASE injection-locked WRC-FPLD transmitter at same power, there is an improvement on receiving power penalty (DeltaP(Receiver)) by 2 dB at BER 10(-9) in back-to-back case, and the receiving power of BER 10(-9) can achieve -24 dBm even after 25km fiber transmission. With additional AWG filtering, the intraband crosstalk effect between the upstream transmitted data and the reflected ASE signal is significantly reduced by 6.3dB. The compromised effects of ER and SNR on BER performance are also elucidated via the modified SNR model for the WRC-FPLD under ASE injection induced gain-saturation condition. The DeltaP(Receiver)/DeltaSNR of 8.89 at same ER condition is more pronounced than the DeltaP(Receiver)/DeltaER of 3.17 obtained under same SNR condition, indicating that the SNR plays a more important role than the ER on enhancing the BER performance.

  2. Electron Density and Two-Channel Neutron Emission Measurements in Steady-State Spherical Inertial-Electrostatically Confined Plasmas, with Review of the One-Dimensional Kinetic Model

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Hrbud, Ivana

    2004-01-01

    Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7 x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the one-dimensional Poisson equation for IEC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with nonfusing hydrogen- 1. The deuterium rates are consistent with predictions from the model.

  3. Electron Density and Two-Channel Neutron Emission Measurements in Steady-State Spherical Inertial-Electrostatically Confined Plasmas, with Review of the 1-D Kinetic Model

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Hrbud, Ivana

    2004-01-01

    Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the 1-D Poisson equation for EC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with non-fusing hydrogen-1. The deuterium rates are consistent with predictions from the model.

  4. Electron Density and Two-Channel Neutron Emission Measurements in Steady-State Spherical Inertial-Electrostatically Confined Plasmas, with Review of the One-Dimensional Kinetic Model

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Hrbud, Ivana

    2004-01-01

    Electron density measurements have been made in steady-state plasmas in a spherical inertial electrostatic confinement (IEC) discharge using microwave interferometry. Plasma cores interior to two cathodes, having diameters of 15 and 23 cm, respectively, were probed over a transverse range of 10 cm with a spatial resolution of about 1.4 cm for buffer gas pressures from 0.2 to 6 Pa in argon and deuterium. The transverse profiles are generally flat, in some cases with eccentric symmetric minima, and give mean densities of from approx. = 0.4 to 7 x 10(exp 10)/cu cm, the density generally increasing with the neutral gas pressure. Numerical solutions of the one-dimensional Poisson equation for IEC plasmas are reviewed and energy distribution functions are identified which give flat transverse profiles. These functions are used with the plasma approximation to obtain solutions which also give densities consistent with the measurements, and a double potential well solution is obtained which has minima qualitatively similar to those observed. Explicit consideration is given to the compatibility of the solutions interior and exterior to the cathode, and to grid transparency. Deuterium fusion neutron emission rates were also measured and found to be isotropic, to within the measurement error, over two simultaneous directions. Anisotropy was observed in residual emissions during operation with nonfusing hydrogen- 1. The deuterium rates are consistent with predictions from the model.

  5. A study of pentaquarks on the lattice with overlap fermions

    SciTech Connect

    N. Mathur; F.X. Lee; A. Alexandru; C. Bennhold; Y. Chen; S.J. Dong; T. Draper; I. Horvath; K.F. Liu; S. Tamhankar; J.B. Zhang

    2004-10-01

    We present a quenched lattice QCD calculation of spin-1/2 five-quark states with uudd{bar s} quark content for both positive and negative parities. We do not observe any bound pentaquark state in these channels for either I = 0 or I = 1. The states we found are consistent with KN scattering states which are checked to exhibit the expected volume dependence of the spectral weight. The results are based on overlap-fermion propagators on two lattices, 12{sup 3} x 28 and 16{sup 3} x 28, with the same lattice spacing of 0.2 fm, and pion mass as low as {approx} 180 MeV.

  6. Absence of evidence for pentaquarks on the lattice

    SciTech Connect

    Holland, Kieran; Juge, K. Jimmy

    2006-04-01

    We study the question of whether or not QCD predicts a pentaquark state {theta}{sup +}. We use the improved, fixed point lattice QCD action which has very little sensitivity to the lattice spacing and also allows us to reach light quark masses. The analysis was performed on a single volume of size (1.8 fm){sup 3}x3.6 fm with lattice spacing of a=0.102 fm. We use the correlation matrix method to identify the ground and excited states in the isospin 0, negative parity channel. In the quenched approximation where dynamical quark effects are omitted, we do not find any evidence for a pentaquark resonance in QCD.

  7. Lattice Boltzmann Equation On a 2D Rectangular Grid

    NASA Technical Reports Server (NTRS)

    Bouzidi, MHamed; DHumieres, Dominique; Lallemand, Pierre; Luo, Li-Shi; Bushnell, Dennis M. (Technical Monitor)

    2002-01-01

    We construct a multi-relaxation lattice Boltzmann model on a two-dimensional rectangular grid. The model is partly inspired by a previous work of Koelman to construct a lattice BGK model on a two-dimensional rectangular grid. The linearized dispersion equation is analyzed to obtain the constraints on the isotropy of the transport coefficients and Galilean invariance for various wave propagations in the model. The linear stability of the model is also studied. The model is numerically tested for three cases: (a) a vortex moving with a constant velocity on a mesh periodic boundary conditions; (b) Poiseuille flow with an arbitrasy inclined angle with respect to the lattice orientation: and (c) a cylinder &symmetrically placed in a channel. The numerical results of these tests are compared with either analytic solutions or the results obtained by other methods. Satisfactory results are obtained for the numerical simulations.

  8. Dynamics of Lattice Kinks

    NASA Astrophysics Data System (ADS)

    Kevrekidis, P. G.; Weinstein, M. I.

    2000-03-01

    In this paper we consider two models of soliton dynamics (the sine Gordon and the \\phi^4 equations) on a 1-dimensional lattice. We are interested in particular in the behavior of their kink-like solutions inside the Peierls- Nabarro barrier and its variation as a function of the discreteness parameter. We find explicitly the asymptotic states of the system for any value of the discreteness parameter and the rates of decay of the initial data to these asymptotic states. We show that genuinely periodic solutions are possible and we identify the regimes of the discreteness parameter for which they are expected to persist. We also prove that quasiperiodic solutions cannot exist. Our results are verified by numerical simulations.

  9. The EMMA Main Ring Lattice.

    SciTech Connect

    Berg,J.S.

    2008-02-21

    I give a brief introduction to the purpose and goals of the EMMA experiment and describe how they will impact the design of the main EMMA ring. I then describe the mathematical model that is used to describe the EMMA lattice. Finally, I show how the different lattice configurations were obtained and list their parameters.

  10. Buckling modes in pantographic lattices

    NASA Astrophysics Data System (ADS)

    Giorgio, Ivan; Della Corte, Alessandro; dell'Isola, Francesco; Steigmann, David J.

    2016-07-01

    We study buckling patterns in pantographic sheets, regarded as two-dimensional continua consisting of lattices of continuously distributed fibers. The fibers are modeled as beams endowed with elastic resistance to stretching, shearing, bending and twist. Included in the theory is a non-standard elasticity due to geodesic bending of the fibers relative to the lattice surface. xml:lang="fr"

  11. Introduction to lattice gauge theory

    NASA Astrophysics Data System (ADS)

    Gupta, R.

    The lattice formulation of Quantum Field Theory (QFT) can be exploited in many ways. We can derive the lattice Feynman rules and carry out weak coupling perturbation expansions. The lattice then serves as a manifestly gauge invariant regularization scheme, albeit one that is more complicated than standard continuum schemes. Strong coupling expansions: these give us useful qualitative information, but unfortunately no hard numbers. The lattice theory is amenable to numerical simulations by which one calculates the long distance properties of a strongly interacting theory from first principles. The observables are measured as a function of the bare coupling g and a gauge invariant cut-off approx. = 1/alpha, where alpha is the lattice spacing. The continuum (physical) behavior is recovered in the limit alpha yields 0, at which point the lattice artifacts go to zero. This is the more powerful use of lattice formulation, so in these lectures the author focuses on setting up the theory for the purpose of numerical simulations to get hard numbers. The numerical techniques used in Lattice Gauge Theories have their roots in statistical mechanics, so it is important to develop an intuition for the interconnection between quantum mechanics and statistical mechanics.

  12. Branes and integrable lattice models

    NASA Astrophysics Data System (ADS)

    Yagi, Junya

    2017-01-01

    This is a brief review of my work on the correspondence between four-dimensional 𝒩 = 1 supersymmetric field theories realized by brane tilings and two-dimensional integrable lattice models. I explain how to construct integrable lattice models from extended operators in partially topological quantum field theories, and elucidate the correspondence as an application of this construction.

  13. Recent progress in lattice QCD

    SciTech Connect

    Sharpe, S.R.

    1992-12-01

    A brief overview of the status of lattice QCD is given, with emphasis on topics relevant to phenomenology. The calculation of the light quark spectrum, the lattice prediction of {alpha} {sub {ovr MS}} (M {sub Z}), and the calculation of f{sub B} are discussed. 3 figs., 3 tabs., 40 refs.

  14. Study of lattice defect vibration

    NASA Technical Reports Server (NTRS)

    Elliott, R. J.

    1969-01-01

    Report on the vibrations of defects in crystals relates how defects, well localized in a crystal but interacting strongly with the other atoms, change the properties of a perfect crystal. The methods used to solve defect problems relate the properties of an imperfect lattice to the properties of a perfect lattice.

  15. Anisotropic lattice models of electrolytes

    NASA Astrophysics Data System (ADS)

    Kobelev, Vladimir; Kolomeisky, Anatoly B.

    2002-11-01

    Systems of charged particles on anisotropic three-dimensional lattices are investigated theoretically using Debye-Huckel theory. It is found that the thermodynamics of these systems strongly depends on the degree of anisotropy. For weakly anisotropic simple cubic lattices, the results indicate the existence of order-disorder phase transitions and a tricritical point, while the possibility of low-density gas-liquid coexistence is suppressed. For strongly anisotropic lattices this picture changes dramatically: The low-density gas-liquid phase separation reappears and the phase diagram exhibits critical, tricritical, and triple points. For body-centered lattices, the low-density gas-liquid phase coexistence is suppressed for all degrees of anisotropy. These results show that the effect of anisotropy in lattice models of electrolytes amounts to reduction of spatial dimensionality.

  16. Lattice models of ionic systems

    NASA Astrophysics Data System (ADS)

    Kobelev, Vladimir; Kolomeisky, Anatoly B.; Fisher, Michael E.

    2002-05-01

    A theoretical analysis of Coulomb systems on lattices in general dimensions is presented. The thermodynamics is developed using Debye-Hückel theory with ion-pairing and dipole-ion solvation, specific calculations being performed for three-dimensional lattices. As for continuum electrolytes, low-density results for simple cubic (sc), body-centered cubic (bcc), and face-centered cubic (fcc) lattices indicate the existence of gas-liquid phase separation. The predicted critical densities have values comparable to those of continuum ionic systems, while the critical temperatures are 60%-70% higher. However, when the possibility of sublattice ordering as well as Debye screening is taken into account systematically, order-disorder transitions and a tricritical point are found on sc and bcc lattices, and gas-liquid coexistence is suppressed. Our results agree with recent Monte Carlo simulations of lattice electrolytes.

  17. Shaping solitons by lattice defects

    SciTech Connect

    Dong Liangwei; Ye Fangwei

    2010-11-15

    We demonstrate the existence of shape-preserving self-localized nonlinear modes in a two-dimensional photonic lattice with a flat-topped defect that covers several lattice sites. The balance of diffraction, defocusing nonlinearity, and optical potential induced by lattices with various forms of defects results in novel families of solitons featuring salient properties. We show that the soliton shape can be controlled by varying the shape of lattice defects. The existence domains of fundamental and vortex solitons in the semi-infinite gap expand with the defect amplitude. Vortex solitons in the semi-infinite gap with rectangular intensity distributions will break into dipole solitons when the propagation constant exceeds a critical value. In the semi-infinite and first-finite gaps, we find that lattices with rectangular defects can support stable vortex solitons which exhibit noncanonical phase structure.

  18. Phase transition in finite density and temperature lattice QCD

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Chen, Ying; Gong, Ming; Liu, Chuan; Liu, Yu-Bin; Liu, Zhao-Feng; Ma, Jian-Ping; Meng, Xiang-Fei; Zhang, Jian-Bo

    2015-06-01

    We investigate the behavior of the chiral condensate in lattice QCD at finite temperature and finite chemical potential. The study was done using two flavors of light quarks and with a series of β and ma at the lattice size 24 × 122 × 6. The calculation was done in the Taylor expansion formalism. We are able to calculate the first and second order derivatives of ≤ft< {\\bar{\\psi} \\psi } \\right> in both isoscalar and isovector channels. With the first derivatives being small, we find that the second derivatives are sizable close to the phase transition and that the magnitude of \\bar{\\psi} \\psi decreases under the influence of finite chemical potential in both channels. Supported by National Natural Science Foundation of China (11335001, 11105153, 11405178), Projects of International Cooperation and Exchanges NSFC (11261130311)

  19. Nonlinear dust-lattice waves: a modified Toda lattice

    SciTech Connect

    Cramer, N. F.

    2008-09-07

    Charged dust grains in a plasma interact with a Coulomb potential, but also with an exponential component to the potential, due to Debye shielding in the background plasma. Here we investigate large-amplitude oscillations and waves in dust-lattices, employing techniques used in Toda lattice analysis. The lattice consists of a linear chain of particles, or a periodic ring as occurs in experimentally observed dust particle clusters. The particle motion has a triangular waveform, and chaotic motion for large amplitude motion of a grain.

  20. A process for co-molding a visible-wavelength photonic crystal and microfluidic channel for biosensing applications

    NASA Astrophysics Data System (ADS)

    Srungarapu, Maurya; Snyder, Chloe E.; Kadiyala, Anand; Hamza, Bashar; Liu, Yuxin; Dawson, Jeremy M.

    2013-05-01

    Rapid DNA analysis systems show promise for reduced DNA analysis times and can be used by untrained operators in point-of-use applications. Throughput improvements can be gained by reducing the polymerase chain reaction (PCR) cycle count, which is used in conventional DNA processing to amplify the DNA to an easily measurable amount. A Photonic Crystal (PhC) can be integrated within a microfluidic channel to enhance fluorescence emission, enabling a reduction in PCR cycling. Most PhCs are fabricated using serial top-down fabrication techniques, resulting in a structure that is challenging to integrate with microfluidic system components. Here, we present a co-integration process for fabricating a Silicon master mold consisting of a visible range PhC lattice and a microfluidic channel. This process can be used to co-fabricate microscale channel and nanoscale lattice structures in polymer or thermoplastic materials. Two dimensional visible range PhCs are fabricated by patterning electron beam resist via E-Beam Lithography (EBL). The patterned features (100-300nm features with 200-450nm pitch) are cured to a glass-like material that is used as a direct etch mask for Reactive Ion Etching. A 200μm wide and 25μm high ridge "strip" is fabricated around the PhC region using Photolithography and Deep RIE etching to form the completed channel and lattice mold. Results indicating the quality of nanoscale features resulting from the molding process in Polydimethylsiloxane (PDMS) will be discussed.

  1. Electron Microdiffraction and Channeling: Theory and Applications.

    NASA Astrophysics Data System (ADS)

    Kim, Young Ock

    1988-12-01

    This thesis treats three related topics in the theory of dynamical kilovolt electron diffraction, and provides one practical application of the theory. The first topic concerns the theory of coherent electron microdiffraction for atomic clusters and precipitates. It has frequently been suggested that strains in small atomic clusters, precipitates and particles could be measured from the High Order Laue Zone (HOLZ) lines in convergent beam electron diffraction patterns (CBED). However the uncertainty principle prevents sharp lines appearing for either very small (sub-nanometer) particles or probe sizes. The visibility of HOLZ lines within the central beam disk of coherent electron microdiffraction patterns has therefore been studied using dynamical electron diffraction theory. The electron source size is also shown to affect HOLZ line visibility. The relationship between these effects is discussed, and the possibility of obtaining three dimensional lattice images in Scanning Transmission Microscopy (STEM) without tilting is also proposed. Coherent electron microdiffraction patterns have been obtained from a new crystalline precipitate found in silicon wafers annealed at 635^circ C for 256 h. The most likely structure is that of keatite (SiO_2, tetragonal). The implications for the study of oxygen precipitation in silicon are discussed. The second theoretical topic concerns the possibilities for determining the sites of adatoms on surfaces by measurements of their X-ray or Auger electron yield as a function of diffraction conditions in the RHEED geometry. Dynamical electron diffraction calculations using a slice method with slices taken normal to the beam are used to reveal the perturbations in the wavefield along the beam path caused by the adsorbate atoms. Ratio methods, in which adsorbate and substrate emission are compared, are discussed, and the use of a reference adsorbate proposed. Finally, the effects of wave-function dimensionality and inelastic localization

  2. Ion channeling revisited

    SciTech Connect

    Doyle, Barney Lee; Corona, Aldo; Nguyen, Anh

    2014-09-01

    A MS Excel program has been written that calculates accidental, or unintentional, ion channeling in cubic bcc, fcc and diamond lattice crystals or polycrystalline materials. This becomes an important issue when simulating the creation by energetic neutrons of point displacement damage and extended defects using beams of ions. All of the tables and graphs in the three Ion Beam Analysis Handbooks that previously had to be manually looked up and read from were programed into Excel in handy lookup tables, or parameterized, for the case of the graphs, using rather simple exponential functions with different powers of the argument. The program then offers an extremely convenient way to calculate axial and planar half-angles and minimum yield or dechanneling probabilities, effects on half-angles of amorphous overlayers, accidental channeling probabilities for randomly oriented crystals or crystallites, and finally a way to automatically generate stereographic projections of axial and planar channeling half-angles. The program can generate these projections and calculate these probabilities for axes and [hkl] planes up to (555).

  3. Hadron scattering lengths in lattice QCD

    SciTech Connect

    Fukugita, M. |; Kuramashi, Y.; Okawa, M.; Mino, H.; Ukawa, A.

    1995-09-01

    For {ital N}-{ital N} scattering a phenomenological study with one-boson exchange potentials indicate that the deuteron becomes unbound if the quark mass is increased beyond 30--40% of the physical value. Simulations with the Wilson action on a 20{sup 4} lattice with heavy quarks with {ital m}{sub {pi}}/{ital m}{sub {rho}}{approx}0.74--0.95 show that the nucleon-nucleon force is attractive for both spin triplet and singlet channels, and that the scatteirng lengths are substantially larger compared to those for the {pi}-{pi} and {pi}-{ital N} cases even for such heavy quarks. The problem of statistical errors, which has to be overcome toward a more realistic calculation of hadron scattering lengths, is discussed.

  4. Rho resonance parameters from lattice QCD

    SciTech Connect

    Guo, Dehua; Alexandru, Andrei; Molina, Raquel; Döring, Michael

    2016-08-01

    We perform a high-precision calculation of the phase shifts for $\\pi$-$\\pi$ scattering in the I = 1, J = 1 channel in the elastic region using elongated lattices with two mass-degenerate quark favors ($N_f = 2$). We extract the $\\rho$ resonance parameters using a Breit-Wigner fit at two different quark masses, corresponding to $m_{\\pi} = 226$MeV and $m_{\\pi} = 315$MeV, and perform an extrapolation to the physical point. The extrapolation is based on a unitarized chiral perturbation theory model that describes well the phase-shifts around the resonance for both quark masses. We find that the extrapolated value, $m_{\\rho} = 720(1)(15)$MeV, is significantly lower that the physical rho mass and we argue that this shift could be due to the absence of the strange quark in our calculation.

  5. Towards Nuclear Reactions from Lattice QCD

    NASA Astrophysics Data System (ADS)

    Briceno, Raul

    2012-10-01

    In this talk I will motivate the evaluation of nuclear reactions cross sections from Lattice Quantum Chromodynamics (LQCD) and discuss challenges associated with such calculations. In particular, I will explore the connection between the energy spectrum of a three-body system in a finite volume and infinite volume scattering matrix elements using an effective field theoretical approach. The implication of this formalism for studying systems composed of a particle and a bound-state below the bound-state break- up, as well as a trimer state will be discussed. I will show that one in fact recovers a Luscher-like quantization condition for sufficiently low-energy up to exponential corrections in the volume due to the size of the two-particle bound-state. I will briefly discuss the similarities of the three-body problem and that of two- body coupled-channels systems and will comment on challenges in applying the formalism above the inelastic threshold.

  6. Lattice QCD: Status and Prospect

    SciTech Connect

    Ukawa, Akira

    2006-02-08

    A brief review is given of the current status and near-future prospect of lattice QCD studies of the Standard Model. After summarizing a bit of history, we describe current attempts toward inclusion of dynamical up, down and strange quarks. Recent results on the light hadron mass spectrum as well as those on the heavy quark quantities are described. Recent work on lattice pentaquark search is summarized. We touch upon the PACS-CS Project for building our next machine for lattice QCD, and conclude with a summary of computer situation and the physics possibilities over the next several years.

  7. Localized structures in Kagome lattices

    SciTech Connect

    Saxena, Avadh B; Bishop, Alan R; Law, K J H; Kevrekidis, P G

    2009-01-01

    We investigate the existence and stability of gap vortices and multi-pole gap solitons in a Kagome lattice with a defocusing nonlinearity both in a discrete case and in a continuum one with periodic external modulation. In particular, predictions are made based on expansion around a simple and analytically tractable anti-continuum (zero coupling) limit. These predictions are then confirmed for a continuum model of an optically-induced Kagome lattice in a photorefractive crystal obtained by a continuous transformation of a honeycomb lattice.

  8. Screened Wigner-lattice model

    NASA Astrophysics Data System (ADS)

    Dias, Mirabeau; Chaba, A. N.

    1983-01-01

    Recently Medeiros e Silva and Mokross proposed the screened Wigner-lattice model which consists of negative point charges on a Bravais lattice interacting through the screened Coulomb potential -Qexp(-λr)r and the positive charge background with the density (QΩ)exp(-λr). We point out the drawbacks of this model and show that by modifying the background charge density to (Qλ24π)Στ-->exp(-λ|r-->-τ-->|)|r-->-τ-->| the screened Coloumb form of the potential emerges naturally as a consequence. Further, this modified screened Wigner-lattice model is free from the defects of the other model.

  9. Random topics in lattice QCD

    SciTech Connect

    Kilcup, G.W.

    1986-01-01

    The author studies the physics of fermions in lattice regularized QCD, both abstractly and numerically. The author presents four papers, in the first showing how one can in principle extract the ..pi../sup +/-..pi../sup 0/ mass difference, in the second using a Monte Carlo simulation to compute the hadron spectrum and certain matrix elements on a small lattice, and in the third analyzing the symmetries of the staggered formulation of lattice fermions. Finally, the author presents preliminary results for the spectrum from a relatively large scale Monte Carlo simulation.

  10. Scaling the Kondo lattice.

    PubMed

    Yang, Yi-feng; Fisk, Zachary; Lee, Han-Oh; Thompson, J D; Pines, David

    2008-07-31

    The origin of magnetic order in metals has two extremes: an instability in a liquid of local magnetic moments interacting through conduction electrons, and a spin-density wave instability in a Fermi liquid of itinerant electrons. This dichotomy between 'local-moment' magnetism and 'itinerant-electron' magnetism is reminiscent of the valence bond/molecular orbital dichotomy present in studies of chemical bonding. The class of heavy-electron intermetallic compounds of cerium, ytterbium and various 5f elements bridges the extremes, with itinerant-electron magnetic characteristics at low temperatures that grow out of a high-temperature local-moment state. Describing this transition quantitatively has proved difficult, and one of the main unsolved problems is finding what determines the temperature scale for the evolution of this behaviour. Here we present a simple, semi-quantitative solution to this problem that provides a basic framework for interpreting the physics of heavy-electron materials and offers the prospect of a quantitative determination of the physical origin of their magnetic ordering and superconductivity. It also reveals the difference between the temperature scales that distinguish the conduction electrons' response to a single magnetic impurity and their response to a lattice of local moments, and provides an updated version of the well-known Doniach diagram.

  11. TRP Channels

    NASA Astrophysics Data System (ADS)

    Voets, Thomas; Owsianik, Grzegorz; Nilius, Bernd

    The TRP superfamily represents a highly diverse group of cation-permeable ion channels related to the product of the Drosophila trp (transient receptor potential) gene. The cloning and characterization of members of this cation channel family has experienced a remarkable growth during the last decade, uncovering a wealth of information concerning the role of TRP channels in a variety of cell types, tissues, and species. Initially, TRP channels were mainly considered as phospholipase C (PLC)-dependent and/or store-operated Ca2+-permeable cation channels. More recent research has highlighted the sensitivity of TRP channels to a broad array of chemical and physical stimuli, allowing them to function as dedicated biological sensors involved in processes ranging from vision to taste, tactile sensation, and hearing. Moreover, the tailored selectivity of certain TRP channels enables them to play key roles in the cellular uptake and/or transepithelial transport of Ca2+, Mg2+, and trace metal ions. In this chapter we give a brief overview of the TRP channel superfamily followed by a survey of current knowledge concerning their structure and activation mechanisms.

  12. Photodissociation of gaseous CH{sub 3}COSH at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Observation of three dissociation channels

    SciTech Connect

    Hu, En-Lan; Tsai, Po-Yu; Fan, He; Lin, King-Chuen

    2013-01-07

    Upon one-photon excitation at 248 nm, gaseous CH{sub 3}C(O)SH is dissociated following three pathways with the products of (1) OCS + CH{sub 4}, (2) CH{sub 3}SH + CO, and (3) CH{sub 2}CO + H{sub 2}S that are detected using time-resolved Fourier-transform infrared emission spectroscopy. The excited state {sup 1}(n{sub O}, {pi}{sup *}{sub CO}) has a radiative lifetime of 249 {+-} 11 ns long enough to allow for Ar collisions that induce internal conversion and enhance the fragment yields. The rate constant of collision-induced internal conversion is estimated to be 1.1 Multiplication-Sign 10{sup -10} cm{sup 3} molecule{sup -1} s{sup -1}. Among the primary dissociation products, a fraction of the CH{sub 2}CO moiety may undergo further decomposition to CH{sub 2}+ CO, of which CH{sub 2} is confirmed by reaction with O{sub 2} producing CO{sub 2}, CO, OH, and H{sub 2}CO. Such a secondary decomposition was not observed previously in the Ar matrix-isolated experiments. The high-resolution spectra of CO are analyzed to determine the ro-vibrational energy deposition of 8.7 {+-} 0.7 kcal/mol, while the remaining primary products with smaller rotational constants are recognized but cannot be spectrally resolved. The CO fragment detected is mainly ascribed to the primary production. A prior distribution method is applied to predict the vibrational distribution of CO that is consistent with the experimental findings.

  13. Rippley Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    18 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a narrow channel on the upper east flank of the martian volcano, Hadriaca Patera. Because it is located on a volcano, most likely this channel was formed by lava, perhaps as a lava tube at which the thin roof later collapsed. Large ripples of windblown sediment now occur on the channel floor; their crests are generally perpendicular to the channel walls, suggesting that winds blow up and down through this channel.

    Location near: 30.5oS, 266.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  14. Rippley Channel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    18 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a narrow channel on the upper east flank of the martian volcano, Hadriaca Patera. Because it is located on a volcano, most likely this channel was formed by lava, perhaps as a lava tube at which the thin roof later collapsed. Large ripples of windblown sediment now occur on the channel floor; their crests are generally perpendicular to the channel walls, suggesting that winds blow up and down through this channel.

    Location near: 30.5oS, 266.2oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

  15. LATTICE QCD AT FINITE TEMPERATURE.

    SciTech Connect

    PETRECZKY, P.

    2005-03-12

    I review recent progress in lattice QCD at finite temperature. Results on the transition temperature will be summarized. Recent progress in understanding in-medium modifications of interquark forces and quarkonia spectral functions at finite temperatures is discussed.

  16. Counting Lattice-Gas Invariants

    DTIC Science & Technology

    2007-11-02

    Dominique d’Humières, Brosl Hasslacher, Pierre Lallemand, Yves Pomeau, and Jean-Pierre Rivet . Lattice gas hydrodynamics in two and three dimensions...177. Springer -Verlag, Februrary 1989. Proceedings of the Winter School, Les Houches, France. 6

  17. Lattice Multiplication: Old and New.

    ERIC Educational Resources Information Center

    Givan, Betty; Karr, Rosemary

    1988-01-01

    The author presents two examples of lattice multiplication followed by a computer algorithm to perform this multiplication. The algorithm is given in psuedocode but could easily be given in Pascal. (PK)

  18. Heavy quarks and lattice QCD

    SciTech Connect

    Andreas S. Kronfeld

    2003-11-05

    This paper is a review of heavy quarks in lattice gauge theory, focusing on methodology. It includes a status report on some of the calculations that are relevant to heavy-quark spectroscopy and to flavor physics.

  19. Channeling through Bent Crystals

    SciTech Connect

    Mack, Stephanie; /Ottawa U. /SLAC

    2012-09-07

    Bent crystals have demonstrated potential for use in beam collimation. A process called channeling is when accelerated particle beams are trapped by the nuclear potentials in the atomic planes within a crystal lattice. If the crystal is bent then the particles can follow the bending angle of the crystal. There are several different effects that are observed when particles travel through a bent crystal including dechanneling, volume capture, volume reflection and channeling. With a crystal placed at the edge of a particle beam, part of the fringe of the beam can be deflected away towards a detector or beam dump, thus helping collimate the beam. There is currently FORTRAN code by Igor Yazynin that has been used to model the passage of particles through a bent crystal. Using this code, the effects mentioned were explored for beam energy that would be seen at the Facility for Advanced Accelerator Experimental Tests (FACET) at a range of crystal orientations with respect to the incoming beam. After propagating 5 meters in vacuum space past the crystal the channeled particles were observed to separate from most of the beam with some noise due to dechanneled particles. Progressively smaller bending radii, with corresponding shorter crystal lengths, were compared and it was seen that multiple scattering decreases with the length of the crystal therefore allowing for cleaner detection of the channeled particles. The input beam was then modified and only a portion of the beam sent through the crystal. With the majority of the beam not affected by the crystal, most particles were not deflected and after propagation the channeled particles were seen to be deflected approximately 5mm. After a portion of the beam travels through the crystal, the entire beam was then sent through a quadrupole magnet, which increased the separation of the channeled particles from the remainder of the beam to a distance of around 20mm. A different code, which was developed at SLAC, was used to

  20. Lattice Studies of Hyperon Spectroscopy

    SciTech Connect

    Richards, David G.

    2016-04-01

    I describe recent progress at studying the spectrum of hadrons containing the strange quark through lattice QCD calculations. I emphasise in particular the richness of the spectrum revealed by lattice studies, with a spectrum of states at least as rich as that of the quark model. I conclude by prospects for future calculations, including in particular the determination of the decay amplitudes for the excited states.

  1. Lattice QCD in rotating frames.

    PubMed

    Yamamoto, Arata; Hirono, Yuji

    2013-08-23

    We formulate lattice QCD in rotating frames to study the physics of QCD matter under rotation. We construct the lattice QCD action with the rotational metric and apply it to the Monte Carlo simulation. As the first application, we calculate the angular momenta of gluons and quarks in the rotating QCD vacuum. This new framework is useful to analyze various rotation-related phenomena in QCD.

  2. Berry Phase in Lattice QCD.

    PubMed

    Yamamoto, Arata

    2016-07-29

    We propose the lattice QCD calculation of the Berry phase, which is defined by the ground state of a single fermion. We perform the ground-state projection of a single-fermion propagator, construct the Berry link variable on a momentum-space lattice, and calculate the Berry phase. As the first application, the first Chern number of the (2+1)-dimensional Wilson fermion is calculated by the Monte Carlo simulation.

  3. Lattice QCD: A Brief Introduction

    NASA Astrophysics Data System (ADS)

    Meyer, H. B.

    A general introduction to lattice QCD is given. The reader is assumed to have some basic familiarity with the path integral representation of quantum field theory. Emphasis is placed on showing that the lattice regularization provides a robust conceptual and computational framework within quantum field theory. The goal is to provide a useful overview, with many references pointing to the following chapters and to freely available lecture series for more in-depth treatments of specifics topics.

  4. Hadronic Resonances from Lattice QCD

    SciTech Connect

    John Bulava; Robert Edwards; George Fleming; K. Jimmy Juge; Adam C. Lichtl; Nilmani Mathur; Colin Morningstar; David Richards; Stephen J. Wallace

    2007-06-16

    The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

  5. Hadronic Resonances from Lattice QCD

    SciTech Connect

    Lichtl, Adam C.; Bulava, John; Morningstar, Colin; Edwards, Robert; Mathur, Nilmani; Richards, David; Fleming, George; Juge, K. Jimmy; Wallace, Stephen J.

    2007-10-26

    The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

  6. The EMMA main ring lattice

    NASA Astrophysics Data System (ADS)

    Berg, J. Scott

    2008-11-01

    The EMMA experiment will study beam dynamics in a linear non-scaling fixed-field alternating gradient (FFAG) accelerator. I give a brief introduction to the purpose and goals of the EMMA experiment and describe how they will impact the design of the main EMMA ring. I then describe the mathematical model that is used to describe the EMMA lattice. Finally, I show how the different lattice configurations were obtained and list their parameters.

  7. Lattice gauge theory for QCD

    SciTech Connect

    DeGrand, T.

    1997-06-01

    These lectures provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1: Basic techniques for QCD and results for hadron spectroscopy using the simplest discretizations; lecture 2: Improved actions--what they are and how well they work; lecture 3: SLAC physics from the lattice-structure functions, the mass of the glueball, heavy quarks and {alpha}{sub s} (M{sub z}), and B-{anti B} mixing. 67 refs., 36 figs.

  8. Emergent three-brane lattices

    SciTech Connect

    Mello Koch, Robert de; Mashile, Grant; Park, Nicholas

    2010-05-15

    In this article the anomalous dimension of a class of operators with a bare dimension of O(N) is studied. The operators considered are dual to excited states of a two giant graviton system. In the Yang-Mills theory they are described by restricted Schur polynomials, labeled with Young diagrams that have at most two columns. In a certain limit the dilatation operator looks like a lattice version of a second derivative, with the lattice emerging from the Young diagram itself.

  9. Coupled-channel scattering on a torus

    SciTech Connect

    Guo, Peng; Dudek, Jozef Jon; Edwards, Robert G.; Szczepaniak, Adam Pawel

    2013-07-01

    Based on the Hamiltonian formalism approach, a generalized Luscher's formula for two particle scattering in both the elastic and coupled-channel cases in moving frames is derived from a relativistic Lippmann-Schwinger equation. Some strategies for extracting scattering amplitudes for a coupled-channel system from the discrete finite-volume spectrum are discussed and illustrated with a toy model of two-channel resonant scattering. This formalism will, in the near future, be used to extract information about hadron scattering from lattice QCD computations.

  10. Coupled-channel scattering on a torus

    DOE PAGES

    Guo, Peng; Dudek, Jozef Jon; Edwards, Robert G.; ...

    2013-07-01

    Based on the Hamiltonian formalism approach, a generalized Luscher's formula for two particle scattering in both the elastic and coupled-channel cases in moving frames is derived from a relativistic Lippmann-Schwinger equation. Some strategies for extracting scattering amplitudes for a coupled-channel system from the discrete finite-volume spectrum are discussed and illustrated with a toy model of two-channel resonant scattering. This formalism will, in the near future, be used to extract information about hadron scattering from lattice QCD computations.

  11. Optimal lattice-structured materials

    DOE PAGES

    Messner, Mark C.

    2016-07-09

    This paper describes a method for optimizing the mesostructure of lattice-structured materials. These materials are periodic arrays of slender members resembling efficient, lightweight macroscale structures like bridges and frame buildings. Current additive manufacturing technologies can assemble lattice structures with length scales ranging from nanometers to millimeters. Previous work demonstrates that lattice materials have excellent stiffness- and strength-to-weight scaling, outperforming natural materials. However, there are currently no methods for producing optimal mesostructures that consider the full space of possible 3D lattice topologies. The inverse homogenization approach for optimizing the periodic structure of lattice materials requires a parameterized, homogenized material model describingmore » the response of an arbitrary structure. This work develops such a model, starting with a method for describing the long-wavelength, macroscale deformation of an arbitrary lattice. The work combines the homogenized model with a parameterized description of the total design space to generate a parameterized model. Finally, the work describes an optimization method capable of producing optimal mesostructures. Several examples demonstrate the optimization method. One of these examples produces an elastically isotropic, maximally stiff structure, here called the isotruss, that arguably outperforms the anisotropic octet truss topology.« less

  12. Optimal lattice-structured materials

    SciTech Connect

    Messner, Mark C.

    2016-07-09

    This paper describes a method for optimizing the mesostructure of lattice-structured materials. These materials are periodic arrays of slender members resembling efficient, lightweight macroscale structures like bridges and frame buildings. Current additive manufacturing technologies can assemble lattice structures with length scales ranging from nanometers to millimeters. Previous work demonstrates that lattice materials have excellent stiffness- and strength-to-weight scaling, outperforming natural materials. However, there are currently no methods for producing optimal mesostructures that consider the full space of possible 3D lattice topologies. The inverse homogenization approach for optimizing the periodic structure of lattice materials requires a parameterized, homogenized material model describing the response of an arbitrary structure. This work develops such a model, starting with a method for describing the long-wavelength, macroscale deformation of an arbitrary lattice. The work combines the homogenized model with a parameterized description of the total design space to generate a parameterized model. Finally, the work describes an optimization method capable of producing optimal mesostructures. Several examples demonstrate the optimization method. One of these examples produces an elastically isotropic, maximally stiff structure, here called the isotruss, that arguably outperforms the anisotropic octet truss topology.

  13. Optimal lattice-structured materials

    SciTech Connect

    Messner, Mark C.

    2016-07-09

    This paper describes a method for optimizing the mesostructure of lattice-structured materials. These materials are periodic arrays of slender members resembling efficient, lightweight macroscale structures like bridges and frame buildings. Current additive manufacturing technologies can assemble lattice structures with length scales ranging from nanometers to millimeters. Previous work demonstrates that lattice materials have excellent stiffness- and strength-to-weight scaling, outperforming natural materials. However, there are currently no methods for producing optimal mesostructures that consider the full space of possible 3D lattice topologies. The inverse homogenization approach for optimizing the periodic structure of lattice materials requires a parameterized, homogenized material model describing the response of an arbitrary structure. This work develops such a model, starting with a method for describing the long-wavelength, macroscale deformation of an arbitrary lattice. The work combines the homogenized model with a parameterized description of the total design space to generate a parameterized model. Finally, the work describes an optimization method capable of producing optimal mesostructures. Several examples demonstrate the optimization method. One of these examples produces an elastically isotropic, maximally stiff structure, here called the isotruss, that arguably outperforms the anisotropic octet truss topology.

  14. Advances in Lattice Quantum Chromodynamics

    NASA Astrophysics Data System (ADS)

    McGlynn, Greg

    In this thesis we make four contributions to the state of the art in numerical lattice simulations of quantum chromodynamics (QCD). First, we present the most detailed investigation yet of the autocorrelations of topological observations in hybrid Monte Carlo simulations of QCD and of the effects of the boundary conditions on these autocorrelations. This results in a numerical criterion for deciding when open boundary conditions are useful for reducing these autocorrelations, which are a major barrier to reliable calculations at fine lattice spacings. Second, we develop a dislocation-enhancing determinant, and demonstrate that it reduces the autocorrelation time of the topological charge. This alleviates problems with slow topological tunneling at fine lattice spacings, enabling simulations on fine lattices to be completed with much less computational effort. Third, we show how to apply the recently developed zMobius technique to hybrid Monte Carlo evolutions with domain wall fermions, achieving nearly a factor of two speedup in the light quark determinant, the single most expensive part of the calculation. The dislocation-enhancing determinant and the zMobius technique have enabled us to begin simulations of fine ensembles with four flavors of dynamical domain wall quarks. Finally, we show how to include the previously-neglected G1 operator in nonperturbative renormalization of the DeltaS = 1 effective weak Hamiltonian on the lattice. This removes an important systematic error in lattice calculations of weak matrix elements, in particular the important K → pipi decay.

  15. Optimal lattice-structured materials

    NASA Astrophysics Data System (ADS)

    Messner, Mark C.

    2016-11-01

    This work describes a method for optimizing the mesostructure of lattice-structured materials. These materials are periodic arrays of slender members resembling efficient, lightweight macroscale structures like bridges and frame buildings. Current additive manufacturing technologies can assemble lattice structures with length scales ranging from nanometers to millimeters. Previous work demonstrates that lattice materials have excellent stiffness- and strength-to-weight scaling, outperforming natural materials. However, there are currently no methods for producing optimal mesostructures that consider the full space of possible 3D lattice topologies. The inverse homogenization approach for optimizing the periodic structure of lattice materials requires a parameterized, homogenized material model describing the response of an arbitrary structure. This work develops such a model, starting with a method for describing the long-wavelength, macroscale deformation of an arbitrary lattice. The work combines the homogenized model with a parameterized description of the total design space to generate a parameterized model. Finally, the work describes an optimization method capable of producing optimal mesostructures. Several examples demonstrate the optimization method. One of these examples produces an elastically isotropic, maximally stiff structure, here called the isotruss, that arguably outperforms the anisotropic octet truss topology.

  16. Searching for X(3872) on the lattice

    NASA Astrophysics Data System (ADS)

    Lee, Song-haeng

    The purpose of this dissertation is to provide high-precision lattice quantum chromodynamics (QCD) simulation results for the mass splittings of low-lying charmonium states as the test of the Standard Model, and, further, to study the nature of a higher mass charmonium-like state called X(3872). Since the discovery of charmonium, it has played an important role in the study of QCD. However, it had been impossible to study charmonium energy levels at a low energy regime in QCD perturbative theory due to color connement, which is the consequence of the SU(3) nonabelian gauge theory in QCD. From this point of view, numerical simulation with lattice QCD is a unique method that provides a nonperturbative, ab initio approach for studying hadronic states governed by the strong interactions. In this dissertation, I describe a high-precision study of the splittings of the low-lying charmonium states, particularly the 1S and 1P states, including a chiral-continuum extrapolation. The highly excited charmonium states, discovered in the past decade, are much more challenging to study because their energy levels lie near or above the D0 D0 threshold, so they cannot be explained within the conventional quark model. Among those, we are interested in the narrow charmonium-like state, X(3872), due to its closeness to the DD* threshold and its possible four-quark nature. Since the X(3872) mass is within 1 MeV of the D D* threshold, it is a strong candidate for a D D* molecular state. Therefore, we use interpolating operators including both the conventional, excited P-wave charmonium state, chi c1, and the DD* open charm state for the isospin 0 channel. I provide the theoretical background for the lattice calculation and the corresponding methodologies, report on our high-precision results for the mass splittings of low-lying charmonium states, I introduce a new methodology called the "staggered variational method", which is a variational method applied to the staggered fermion

  17. The site occupation and valence of Mn ions in the crystal lattice of Sr{sub 4}Al{sub 14}O{sub 25} and its deep red emission for high color-rendering white light-emitting diodes

    SciTech Connect

    Chen, Lei; Xue, Shaochan; Chen, Xiuling; Bahader, Ali; Deng, Xiaorong; Zhao, Erlong; Jiang, Yang; Chen, Shifu; Chan, Ting-Shan; Zhao, Zhi; Zhang, Wenhua

    2014-12-15

    Highlights: • Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were identified using XANES and EPR. • Red luminescence was attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. • The Mn{sup 3+} incorporated in the center of AlO{sub 4} tetrahedron was non-luminescent. • The bond-valence theory was used to analyze the effective valences of cations. • A white LED device with CRI up to Ra 93.23 was packaged by using the red phosphor. - Abstract: The synthesis and component of red phosphor, Sr{sub 4}Al{sub 14}O{sub 25}: Mn, were optimized for application in white light-emitting diodes. The microstructure and morphology were investigated by the X-ray diffraction and scanning electron microscopy. Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were discriminated using the electron paramagnetic resonance and X-ray absorption near-edge structure spectroscopy techniques. The bond-valence theory was used to analyze the effective valences of Sr{sup 2+} and Al{sup 3+} in Sr{sub 4}Al{sub 14}O{sub 25}. As a result, the strong covalence of Al{sup 3+} in the AlO{sub 4} tetrahedron other than in the AlO{sub 6} octahedron is disclosed. The deep red emission is attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. The mechanism of energy transfer is mainly through dipole–dipole interaction, revealed by the analyses of critical distance and concentration quench. A high color rendering white LED prototype with color-rendering index up to Ra 93.23 packaged by using the red phosphor demonstrates its applicability.

  18. A Ten Channel Temperature Controller.

    DTIC Science & Technology

    1984-05-01

    R 1D-A152 664 R TEN CHANNEL TEMPERATURE CONTROLLER(U) ROYAL AXRCRAFT 1/i ESTABLISHMENT FARNBOROUGH ( ENGLAND ) D H LISTER MAY 84 U A E RAE-T-P-1926...obtained with the design and build of a multi-channel temperature control unit for the first NGTE emissions van .While this was a platinum resistance...voltage switch, had proved highly reliable. It was decided therefore to capitalise on this experience and build, in-house, a modular multi-channel unit . A

  19. Phyllotaxis of flux lattices in layered superconductors

    SciTech Connect

    Levitov, L.S. )

    1991-01-14

    The geometry of a flux lattice pinned by superconducting layers is studied. Under variation of magnetic field the lattice undergoes an infinite sequence of continuous transitions corresponding to different ways of selection of shortest distances. All possible lattices form a hierarchical structure identified as the hierarchy of Farey numbers. It is shown that dynamically accessible lattices are characterized by pairs of consecutive Fibonacci numbers.

  20. Lattice Structure in Astrophysics: A reconsideration of White Dwarfs, Variables, and Wolf-Rayet Stars

    NASA Astrophysics Data System (ADS)

    Robitaille, Pierre-Marie

    2016-03-01

    Stars of the main sequence display a mass-luminosity relation which indicates that they share a common building block (hydrogen) and lattice structure (hexagonal planar) with the solar photosphere. White dwarfs however display very low luminosity in spite of their elevated color temperature. Rather than postulate that these stars represent degenerate matter, as Eddington and Chandrasekhar were forced to assume given their gaseous models, within the context of a Liquid Metallic Hydrogen Solar Model white dwarfs might simply be thought as possessing a different lattice structure (e.g. body centered cubic) and hence a lowered emissivity. They do not need to possess exceeding densities, reduced radii, and degeneracy in order to account for their lowered emissivity. Similarly, variable stars might well be oscillating between lattices types wherein the energy differences involved in the transformations are small. Other stars, such as Wolf-Rayet stars, which lack photospheric emission, might be too hot to enable a discrete lattice to form. Though condensed, the photosphere in that case would have a lattice which is so poorly organized that its emissivity is trivial. Nonetheless, the broad emission lines of Wolf-Rayet stars indicates that these objects are not breaking apart but rather, are important sites of condensation.

  1. Mechanosensitive Channels

    NASA Astrophysics Data System (ADS)

    Martinac, Boris

    Living cells are exposed to a variety of mechanical stimuli acting throughout the biosphere. The range of the stimuli extends from thermal molecular agitation to potentially destructive cell swelling caused by osmotic pressure gradients. Cellular membranes present a major target for these stimuli. To detect mechanical forces acting upon them cell membranes are equipped with mechanosensitive (MS) ion channels. Functioning as molecular mechanoelectrical transducers of mechanical forces into electrical and/or chemical intracellular signals these channels play a critical role in the physiology of mechanotransduction. Studies of prokaryotic MS channels and recent work on MS channels of eukaryotes have significantly increased our understanding of their gating mechanism, physiological functions, and evolutionary origins as well as their role in the pathology of disease.

  2. Channel catfish

    USDA-ARS?s Scientific Manuscript database

    This book chapter provides a comprehensive overview of channel catfish aquaculture. Sections include fish biology; commercial culture; culture facilities; production practices; water quality management; nutrition, feeding and feed formulation; infectious diseases; harvesting and processing; and the...

  3. Infrared and terahertz radiation of a crystal at axial channeling

    NASA Astrophysics Data System (ADS)

    Epp, V.; Mitrofanova, T. G.; Zotova, M. A.

    2015-08-01

    Basic properties of radiation of a crystal lattice excited by an axial channeling particle are considered. It is shown that a coherent radiation of atoms occurs if the frequency of oscillations of the channeled particle comes to a resonance with the vibrational mode of the crystal. Spectral and angular distribution of radiation and its polarization are calculated. In case of a relativistic channeled particle, the radiation of atoms is generated into a narrow cone in the direction of a crystallographic axis along which the particle is channeling. The radiation of atoms exited at axial channelling has significant degree of circular polarization.

  4. Role of Lattice Coupling in Establishing Electronic and Magnetic Properties in Quasi-One-Dimensional Cuprates

    SciTech Connect

    Lee, W. S.; Johnston, S.; Moritz, B.; Lee, J.; Yi, M.; Zhou, K. J.; Schmitt, T.; Patthey, L.; Strocov, V.; Kudo, K.; Koike, Y.; van den Brink, J.; Devereaux, T. P.; Shen, Z. X.

    2013-06-25

    High resolution resonant inelastic x-ray scattering has been performed to reveal the role of lattice coupling in a family of quasi-1D insulating cuprates, Ca2+5xY2-5xCu5O10. Site-dependent low-energy excitations arising from progressive emissions of a 70 meV lattice vibrational mode are resolved for the first time, providing a direct measurement of electron-lattice coupling strength. We show that such electron-lattice coupling causes doping-dependent distortions of the Cu-O-Cu bond angle, which sets the intrachain spin exchange interactions. Our results indicate that the lattice degrees of freedom are fully integrated into the electronic behavior in low-dimensional systems.

  5. Lattice vertex algebras on general even, self-dual lattices

    NASA Astrophysics Data System (ADS)

    Kleinschmidt, Axel

    2003-07-01

    In this note we analyse the Lie algebras of physical states stemming from lattice constructions on general even, self-dual lattices Gammap,q with p geq q. It is known that if the lattice is at most lorentzian, the resulting Lie algebra is of generalized Kac-Moody type (or has a quotient that is). We show that this is not true as soon as q geq 1. By studying a certain sublattice in the case q > 1 we obtain results that lead to the conclusion that the resulting non-GKM Lie algebra cannot be described conveniently in terms of generators and relations and belongs to a new and qualitatively different class of Lie algebras.

  6. Hamiltonian tomography of photonic lattices

    NASA Astrophysics Data System (ADS)

    Ma, Ruichao; Owens, Clai; LaChapelle, Aman; Schuster, David I.; Simon, Jonathan

    2017-06-01

    In this paper we introduce an approach to Hamiltonian tomography of noninteracting tight-binding photonic lattices. To begin with, we prove that the matrix element of the low-energy effective Hamiltonian between sites α and β may be obtained directly from Sα β(ω ) , the (suitably normalized) two-port measurement between sites α and β at frequency ω . This general result enables complete characterization of both on-site energies and tunneling matrix elements in arbitrary lattice networks by spectroscopy, and suggests that coupling between lattice sites is a topological property of the two-port spectrum. We further provide extensions of this technique for measurement of band projectors in finite, disordered systems with good band flatness ratios, and apply the tool to direct real-space measurement of the Chern number. Our approach demonstrates the extraordinary potential of microwave quantum circuits for exploration of exotic synthetic materials, providing a clear path to characterization and control of single-particle properties of Jaynes-Cummings-Hubbard lattices. More broadly, we provide a robust, unified method of spectroscopic characterization of linear networks from photonic crystals to microwave lattices and everything in between.

  7. Quantum lattice model solver HΦ

    NASA Astrophysics Data System (ADS)

    Kawamura, Mitsuaki; Yoshimi, Kazuyoshi; Misawa, Takahiro; Yamaji, Youhei; Todo, Synge; Kawashima, Naoki

    2017-08-01

    HΦ [aitch-phi ] is a program package based on the Lanczos-type eigenvalue solution applicable to a broad range of quantum lattice models, i.e., arbitrary quantum lattice models with two-body interactions, including the Heisenberg model, the Kitaev model, the Hubbard model and the Kondo-lattice model. While it works well on PCs and PC-clusters, HΦ also runs efficiently on massively parallel computers, which considerably extends the tractable range of the system size. In addition, unlike most existing packages, HΦ supports finite-temperature calculations through the method of thermal pure quantum (TPQ) states. In this paper, we explain theoretical background and user-interface of HΦ. We also show the benchmark results of HΦ on supercomputers such as the K computer at RIKEN Advanced Institute for Computational Science (AICS) and SGI ICE XA (Sekirei) at the Institute for the Solid State Physics (ISSP).

  8. Algebraic Lattices in QFT Renormalization

    NASA Astrophysics Data System (ADS)

    Borinsky, Michael

    2016-07-01

    The structure of overlapping subdivergences, which appear in the perturbative expansions of quantum field theory, is analyzed using algebraic lattice theory. It is shown that for specific QFTs the sets of subdivergences of Feynman diagrams form algebraic lattices. This class of QFTs includes the standard model. In kinematic renormalization schemes, in which tadpole diagrams vanish, these lattices are semimodular. This implies that the Hopf algebra of Feynman diagrams is graded by the coradical degree or equivalently that every maximal forest has the same length in the scope of BPHZ renormalization. As an application of this framework, a formula for the counter terms in zero-dimensional QFT is given together with some examples of the enumeration of primitive or skeleton diagrams.

  9. Screened Wigner-lattice model

    SciTech Connect

    Dias, M.; Chaba, A.N.

    1983-01-15

    Recently Medeiros e Silva and Mokross proposed the screened Wigner-lattice model which consists of negative point charges on a Bravais lattice interacting through the screened Coulomb potential -Q exp(-lambdar)/r and the positive charge background with the density (Q/..cap omega..) exp(-lambdar). We point out the drawbacks of this model and show that by modifying the background charge density to (Qlambda/sup 2//4..pi..) summation/sub tau-arrow-right/ exp(-lambdaVertical Barr-tau-arrow-rightVertical Bar)/Vertical Barr-tau-arrow-rightVertical Bar the screened Coloumb form of the potential emerges naturally as a consequence. Further, this modified screened Wigner-lattice model is free from the defects of the other model.

  10. Lattice QCD Beyond Ground States

    SciTech Connect

    Huey-Wen Lin; Saul D. Cohen

    2007-09-11

    In this work, we apply black box methods (methods not requiring input) to find excited-state energies. A variety of such methods for lattice QCD were introduced at the 3rd iteration of the numerical workshop series. We first review a selection of approaches that have been used in lattice calculations to determine multiple energy states: multiple correlator fits, the variational method and Bayesian fitting. In the second half, we will focus on a black box method, the multi-effective mass. We demonstrate the approach on a toy model, as well as on real lattice data, extracting multiple states from single correlators. Without complicated operator construction or specialized fitting programs, the black box method shows good consistency with the traditional approaches.

  11. Subwavelength lattice optics by evolutionary design.

    PubMed

    Huntington, Mark D; Lauhon, Lincoln J; Odom, Teri W

    2014-12-10

    This paper describes a new class of structured optical materials--lattice opto-materials--that can manipulate the flow of visible light into a wide range of three-dimensional profiles using evolutionary design principles. Lattice opto-materials are based on the discretization of a surface into a two-dimensional (2D) subwavelength lattice whose individual lattice sites can be controlled to achieve a programmed optical response. To access a desired optical property, we designed a lattice evolutionary algorithm that includes and optimizes contributions from every element in the lattice. Lattice opto-materials can exhibit simple properties, such as on- and off-axis focusing, and can also concentrate light into multiple, discrete spots. We expanded the unit cell shapes of the lattice to achieve distinct, polarization-dependent optical responses from the same 2D patterned substrate. Finally, these lattice opto-materials can also be combined into architectures that resemble a new type of compound flat lens.

  12. Three-dimensional simulations of pressure-driven displacement flow of two immiscible liquids using a multiphase Lattice Boltzmann approach

    NASA Astrophysics Data System (ADS)

    Redapangu, Prasanna R.; Sahu, Kirti Chandra; Vanka, S. P.

    2013-11-01

    A three-dimensional multiphase lattice Boltzmann approach is used to study the pressure-driven displacement flow of two immiscible liquids of different densities and viscosities in an inclined square duct. A three-dimensional-fifteen-velocity (D3Q15) lattice model is used. The simulations are performed on a graphics processing unit (GPU) based machine. The effects of channel inclination, viscosity and density contrasts are investigated. The contours of the density and the average viscosity profiles in different planes are plotted and compared with two dimensional simulations. We demonstrate that the flow dynamics in three-dimensional channel is quite different as compared to that of two-dimensional channel. In particular, we found that the flow is relatively more coherent in three-dimensional channel than that in two-dimensional channel. A new screw-type instability is seen in the three-dimensional channel which cannot be observed in two-dimensional simulations.

  13. Tetraquark states from lattice QCD

    SciTech Connect

    Mathur, Nilmani

    2011-10-24

    Recently there have been considerable interests in studying hadronic states beyond the usual two and three quark configurations. With the renewed experimental interests in {sigma}(600) and the inability of quark model to incorporate too many light scalar mesons, it is quite appropriate to study hadronic states with four quark configurations. Moreover, some of the newly observed charmed hadrons may well be described by four quark configurations. Lattice QCD is perhaps the most desirable tool to adjudicate the theoretical controversy of the scalar mesons and to interpret the structures of the newly observed charmed states. Here we briefly reviewed the lattice studies of four-quark hadrons.

  14. Lattice QCD and Nuclear Physics

    SciTech Connect

    Konstantinos Orginos

    2007-03-01

    A steady stream of developments in Lattice QCD have made it possible today to begin to address the question of how nuclear physics emerges from the underlying theory of strong interactions. Central role in this understanding play both the effective field theory description of nuclear forces and the ability to perform accurate non-perturbative calculations in lo w energy QCD. Here I present some recent results that attempt to extract important low energy constants of the effective field theory of nuclear forces from lattice QCD.

  15. Nuclear Physics from Lattice QCD

    SciTech Connect

    William Detmold, Silas Beane, Konstantinos Orginos, Martin Savage

    2011-01-01

    We review recent progress toward establishing lattice Quantum Chromodynamics as a predictive calculational framework for nuclear physics. A survey of the current techniques that are used to extract low-energy hadronic scattering amplitudes and interactions is followed by a review of recent two-body and few-body calculations by the NPLQCD collaboration and others. An outline of the nuclear physics that is expected to be accomplished with Lattice QCD in the next decade, along with estimates of the required computational resources, is presented.

  16. Continuous Lattices and Mathematical Morphology

    DTIC Science & Technology

    1998-06-01

    ARMY RESEARCH LABORATORY Continuous Lattices and Mathematical Morphology by Dennis W. McGuire ARL-TR-1548 ^»»».■■SiSIIIBRHH^ June 1998...Research Laboratory Adelphi, MD 20783-1197 ARL-TR-1548 June 1998 Continuous Lattices and Mathematical Morphology Dennis W. McGuire Sensors and...Washington DC 20301-7100 AMCOM MRDEC Atta AMSMI-RD W C McCorkle Redstone Arsenal AL 35898-5240 Army RsrchPhysics Div Atta AMXRO-EMCS Assoc Dir Math

  17. Nucleon Structure from Lattice QCD

    SciTech Connect

    Haegler, Philipp

    2011-10-24

    Hadron structure calculations in lattice QCD have seen substantial progress during recent years. We illustrate the achievements that have been made by discussing latest lattice results for a limited number of important observables related to nucleon form factors and generalized parton distributions. A particular focus is placed on the decomposition of the nucleon spin 1/2 in terms of quark spin and orbital angular momentum contributions. Results and limitations of the necessary chiral extrapolations based on ChPT will be briefly discussed.

  18. Negative-viscosity lattice gases

    SciTech Connect

    Rothman, D.H. )

    1989-08-01

    A new irreversible collision rule is introduced for lattice-gas automata. The rule maximizes the flux of momentum in the direction of the local momentum gradient, yielding a negative shear viscosity. Numerically results in 2D show that the negative viscosity leads to the spontaneous ordering of the velocity field, with vorticity resolvable down to one lattice-link length. The new rule may be used in conjunction with previously proposed collision rules to yield a positive shear viscosity lower than the previous rules provide. In particular, Poiseuille flow tests demonstrate a decrease in viscosity by more than a factor of 2.

  19. Kondo length in bosonic lattices

    NASA Astrophysics Data System (ADS)

    Giuliano, Domenico; Sodano, Pasquale; Trombettoni, Andrea

    2017-09-01

    Motivated by the fact that the low-energy properties of the Kondo model can be effectively simulated in spin chains, we study the realization of the effect with bond impurities in ultracold bosonic lattices at half filling. After presenting a discussion of the effective theory and of the mapping of the bosonic chain onto a lattice spin Hamiltonian, we provide estimates for the Kondo length as a function of the parameters of the bosonic model. We point out that the Kondo length can be extracted from the integrated real-space correlation functions, which are experimentally accessible quantities in experiments with cold atoms.

  20. Chiral symmetry on the lattice

    SciTech Connect

    Creutz, M.

    1994-11-01

    The author reviews some of the difficulties associated with chiral symmetry in the context of a lattice regulator. The author discusses the structure of Wilson Fermions when the hopping parameter is in the vicinity of its critical value. Here one flavor contrasts sharply with the case of more, where a residual chiral symmetry survives anomalies. The author briefly discusses the surface mode approach, the use of mirror Fermions to cancel anomalies, and finally speculates on the problems with lattice versions of the standard model.

  1. Lattice Green's Function for the Body-Centered Cubic Lattice

    NASA Astrophysics Data System (ADS)

    Sakaji, A. J.

    2002-05-01

    An expression for the Green's function (GF) of Body-Centered Cubic (BCC) lat tice is evaluated analytically and numerically for a single impurity lattice. Th e density of states (DOS), phase shift, and scattering cross section are express ed in terms of complete elliptic integrals of the first kind.

  2. English Channel

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The cloud covered earthscape of Northern Europe demonstrates the difficulty of photographing this elusive subject from space. The English Channel (51.0N, 1.5E) separating the British Islands from Europe is in the center of the scene. The white cliffs of Dover on the SE coast of the UK, the Thames River estuary and a partial view of the city of London can be seen on the north side of the Channel while the Normandy coast of France is to the south.

  3. English Channel

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The cloud covered earthscape of Northern Europe demonstrates the difficulty of photographing this elusive subject from space. The English Channel (51.0N, 1.5E) separating the British Islands from Europe is in the center of the scene. The white cliffs of Dover on the SE coast of the UK, the Thames River estuary and a partial view of the city of London can be seen on the north side of the Channel while the Normandy coast of France is to the south.

  4. Lattice Boltzmann method for the Saint-Venant equations

    NASA Astrophysics Data System (ADS)

    Liu, Haifei; Wang, Hongda; Liu, Shu; Hu, Changwei; Ding, Yu; Zhang, Jie

    2015-05-01

    The Saint-Venant equations represent the hydrodynamic principles of unsteady flows in open channel network through a set of non-linear partial differential equations. In this paper, a new lattice Boltzmann approach to solving the one-dimensional Saint-Venant equations (LABSVE) is developed, demonstrating the variation of discharge and sectional area with external forces, such as bed slope and bed friction. Our research recovers the Saint-Venant equations through deducing the Chapman-Enskog expansion on the lattice Boltzmann equation, which is a mesoscopic technique, bridging the molecular movement and macroscopic physical variables. It is also a fully explicit process, providing simplicity for programming. The model is verified by three benchmark tests: (i) a one-dimensional subcritical gradient flow; (ii) a dam-break wave flow; (iii) a flood event on the Yongding River. The results showed the accuracy of the proposed method and its good applicability in solving Saint-Venant problems.

  5. Spin-Lattice Coupling and Superconductivity in Fe Pnictides

    DOE PAGES

    Egami, T.; Fine, B. V.; Parshall, D.; ...

    2010-01-01

    We consider strong spin-lattice and spin-phonon coupling in iron pnictides and discuss its implications on superconductivity. Strong magneto-volume effect in iron compounds has long been known as the Invar effect. Fe pnictides also exhibit this effect, reflected in particular on the dependence of the magnetic moment on the atomic volume of Fe defined by the positions of the nearest neighbor atoms. Through the phenomenological Landau theory, developed on the basis of the calculations by the density functional theory (DFT) and the experimental results, we quantify the strength of the spin-lattice interaction as it relates to the Stoner criterion for themore » onset of magnetism. We suggest that the coupling between electrons and phonons through the spin channel may be sufficiently strong to be an important part of the superconductivity mechanism in Fe pnictides.« less

  6. Toward the excited isoscalar meson spectrum from lattice QCD

    SciTech Connect

    Dudek, Jozef J.; Edwards, Robert G.; Guo, Peng; Thomas, Christopher E.

    2013-11-18

    We report on the extraction of an excited spectrum of isoscalar mesons using lattice QCD. Calculations on several lattice volumes are performed with a range of light quark masses corresponding to pion masses down to about ~400 MeV. The distillation method enables us to evaluate the required disconnected contributions with high statistical precision for a large number of meson interpolating fields. We find relatively little mixing between light and strange in most JPC channels; one notable exception is the pseudoscalar sector where the approximate SU(3)F octet, singlet structure of the η, η' is reproduced. We extract exotic JPC states, identified as hybrid mesons in which an excited gluonic field is coupled to a color-octet qqbar pair, along with non-exotic hybrid mesons embedded in a qq¯-like spectrum.

  7. Toward the excited isoscalar meson spectrum from lattice QCD

    DOE PAGES

    Dudek, Jozef J.; Edwards, Robert G.; Guo, Peng; ...

    2013-11-18

    We report on the extraction of an excited spectrum of isoscalar mesons using lattice QCD. Calculations on several lattice volumes are performed with a range of light quark masses corresponding to pion masses down to about ~400 MeV. The distillation method enables us to evaluate the required disconnected contributions with high statistical precision for a large number of meson interpolating fields. We find relatively little mixing between light and strange in most JPC channels; one notable exception is the pseudoscalar sector where the approximate SU(3)F octet, singlet structure of the η, η' is reproduced. We extract exotic JPC states, identifiedmore » as hybrid mesons in which an excited gluonic field is coupled to a color-octet qqbar pair, along with non-exotic hybrid mesons embedded in a qq¯-like spectrum.« less

  8. Many-body lattice wave functions from conformal blocks

    NASA Astrophysics Data System (ADS)

    Montes, Sebastián; Rodríguez-Laguna, Javier; Tu, Hong-Hao; Sierra, Germán

    2017-02-01

    We introduce a general framework to construct many-body lattice wave functions starting from the conformal blocks (CBs) of rational conformal field theories (RCFTs). We discuss the different ways of encoding the physical degrees of freedom of the lattice system using both the internal symmetries of the theory and the fusion channels of the CBs. We illustrate this construction both by revisiting the known Haldane-Shastry model and by providing a novel implementation for the Ising RCFT. In the latter case, we find a connection to the Ising transverse field (ITF) spin chain via the Kramers-Wannier duality and the Temperley-Lieb-Jones algebra. We also find evidence that the ground state of the finite-size critical ITF Hamiltonian corresponds exactly to the wave function obtained from CBs of spin fields.

  9. Lattice fluid dynamics from perfect discretizations of continuum flows

    SciTech Connect

    Katz, E.; Wiese, U.

    1998-11-01

    We use renormalization group methods to derive equations of motion for large scale variables in fluid dynamics. The large scale variables are averages of the underlying continuum variables over cubic volumes and naturally exist on a lattice. The resulting lattice dynamics represents a perfect discretization of continuum physics, i.e., grid artifacts are completely eliminated. Perfect equations of motion are derived for static, slow flows of incompressible, viscous fluids. For Hagen-Poiseuille flow in a channel with a square cross section the equations reduce to a perfect discretization of the Poisson equation for the velocity field with Dirichlet boundary conditions. The perfect large scale Poisson equation is used in a numerical simulation and is shown to represent the continuum flow exactly. For nonsquare cross sections one can use a numerical iterative procedure to derive flow equations that are approximately perfect. {copyright} {ital 1998} {ital The American Physical Society}

  10. Toward the excited isoscalar meson spectrum from lattice QCD

    NASA Astrophysics Data System (ADS)

    Dudek, Jozef J.; Edwards, Robert G.; Guo, Peng; Thomas, Christopher E.

    2013-11-01

    We report on the extraction of an excited spectrum of isoscalar mesons using lattice QCD. Calculations on several lattice volumes are performed with a range of light quark masses corresponding to pion masses down to ˜400MeV. The distillation method enables us to evaluate the required disconnected contributions with high statistical precision for a large number of meson interpolating fields. We find relatively little mixing between (1)/(2)(uu¯+dd¯) and ss¯ in most JPC channels; one notable exception is the pseudoscalar sector where the approximate SU(3)F octet, singlet structure of the η, η' is reproduced. We extract exotic JPC states, identified as hybrid mesons in which an excited gluonic field is coupled to a color-octet qq¯ pair, along with nonexotic hybrid mesons embedded in a qq¯-like spectrum.

  11. Lattice Location of Mg in GaN: A Fresh Look at Doping Limitations

    NASA Astrophysics Data System (ADS)

    Wahl, U.; Amorim, L. M.; Augustyns, V.; Costa, A.; David-Bosne, E.; Lima, T. A. L.; Lippertz, G.; Correia, J. G.; da Silva, M. R.; Kappers, M. J.; Temst, K.; Vantomme, A.; Pereira, L. M. C.

    2017-03-01

    Radioactive 27Mg (t1 /2=9.5 min ) was implanted into GaN of different doping types at CERN's ISOLDE facility and its lattice site determined via β- emission channeling. Following implantations between room temperature and 800 °C , the majority of 27Mg occupies the substitutional Ga sites; however, below 350 °C significant fractions were also found on interstitial positions ˜0.6 Å from ideal octahedral sites. The interstitial fraction of Mg was correlated with the GaN doping character, being highest (up to 31%) in samples doped p type with 2 ×1019 cm-3 stable Mg during epilayer growth, and lowest in Si-doped n -GaN, thus giving direct evidence for the amphoteric character of Mg. Implanting above 350 °C converts interstitial 27Mg to substitutional Ga sites, which allows estimating the activation energy for migration of interstitial Mg as between 1.3 and 2.0 eV.

  12. Inherent secure communications using lattice based waveform design.

    SciTech Connect

    Pugh, Matthew Owen

    2013-12-01

    The wireless communications channel is innately insecure due to the broadcast nature of the electromagnetic medium. Many techniques have been developed and implemented in order to combat insecurities and ensure the privacy of transmitted messages. Traditional methods include encrypting the data via cryptographic methods, hiding the data in the noise floor as in wideband communications, or nulling the signal in the spatial direction of the adversary using array processing techniques. This work analyzes the design of signaling constellations, i.e. modulation formats, to combat eavesdroppers from correctly decoding transmitted messages. It has been shown that in certain channel models the ability of an adversary to decode the transmitted messages can be degraded by a clever signaling constellation based on lattice theory. This work attempts to optimize certain lattice parameters in order to maximize the security of the data transmission. These techniques are of interest because they are orthogonal to, and can be used in conjunction with, traditional security techniques to create a more secure communication channel.

  13. Lattice continuum and diffusional creep

    NASA Astrophysics Data System (ADS)

    Mesarovic, Sinisa Dj.

    2016-04-01

    Diffusional creep is characterized by growth/disappearance of lattice planes at the crystal boundaries that serve as sources/sinks of vacancies, and by diffusion of vacancies. The lattice continuum theory developed here represents a natural and intuitive framework for the analysis of diffusion in crystals and lattice growth/loss at the boundaries. The formulation includes the definition of the Lagrangian reference configuration for the newly created lattice, the transport theorem and the definition of the creep rate tensor for a polycrystal as a piecewise uniform, discontinuous field. The values associated with each crystalline grain are related to the normal diffusional flux at grain boundaries. The governing equations for Nabarro-Herring creep are derived with coupled diffusion and elasticity with compositional eigenstrain. Both, bulk diffusional dissipation and boundary dissipation accompanying vacancy nucleation and absorption, are considered, but the latter is found to be negligible. For periodic arrangements of grains, diffusion formally decouples from elasticity but at the cost of a complicated boundary condition. The equilibrium of deviatorically stressed polycrystals is impossible without inclusion of interface energies. The secondary creep rate estimates correspond to the standard Nabarro-Herring model, and the volumetric creep is small. The initial (primary) creep rate is estimated to be much larger than the secondary creep rate.

  14. On Some Periodic Toda Lattices

    PubMed Central

    Kac, M.; Van Moerbeke, Pierre

    1975-01-01

    A discrete version of Floquet's theory is developed and applied to a system of non-linear differential equations related to the periodic Toda lattice. A special solution previously found by Toda is thus seen to fit into the formalism of inverse scattering problems. PMID:16592244

  15. Subwavelength vortical plasmonic lattice solitons.

    PubMed

    Ye, Fangwei; Mihalache, Dumitru; Hu, Bambi; Panoiu, Nicolae C

    2011-04-01

    We present a theoretical study of vortical plasmonic lattice solitons, which form in two-dimensional arrays of metallic nanowires embedded into nonlinear media with both focusing and defocusing Kerr nonlinearities. Their existence, stability, and subwavelength spatial confinement are investigated in detail.

  16. Lattice continuum and diffusional creep

    PubMed Central

    2016-01-01

    Diffusional creep is characterized by growth/disappearance of lattice planes at the crystal boundaries that serve as sources/sinks of vacancies, and by diffusion of vacancies. The lattice continuum theory developed here represents a natural and intuitive framework for the analysis of diffusion in crystals and lattice growth/loss at the boundaries. The formulation includes the definition of the Lagrangian reference configuration for the newly created lattice, the transport theorem and the definition of the creep rate tensor for a polycrystal as a piecewise uniform, discontinuous field. The values associated with each crystalline grain are related to the normal diffusional flux at grain boundaries. The governing equations for Nabarro–Herring creep are derived with coupled diffusion and elasticity with compositional eigenstrain. Both, bulk diffusional dissipation and boundary dissipation accompanying vacancy nucleation and absorption, are considered, but the latter is found to be negligible. For periodic arrangements of grains, diffusion formally decouples from elasticity but at the cost of a complicated boundary condition. The equilibrium of deviatorically stressed polycrystals is impossible without inclusion of interface energies. The secondary creep rate estimates correspond to the standard Nabarro–Herring model, and the volumetric creep is small. The initial (primary) creep rate is estimated to be much larger than the secondary creep rate. PMID:27274696

  17. Lattice continuum and diffusional creep.

    PubMed

    Mesarovic, Sinisa Dj

    2016-04-01

    Diffusional creep is characterized by growth/disappearance of lattice planes at the crystal boundaries that serve as sources/sinks of vacancies, and by diffusion of vacancies. The lattice continuum theory developed here represents a natural and intuitive framework for the analysis of diffusion in crystals and lattice growth/loss at the boundaries. The formulation includes the definition of the Lagrangian reference configuration for the newly created lattice, the transport theorem and the definition of the creep rate tensor for a polycrystal as a piecewise uniform, discontinuous field. The values associated with each crystalline grain are related to the normal diffusional flux at grain boundaries. The governing equations for Nabarro-Herring creep are derived with coupled diffusion and elasticity with compositional eigenstrain. Both, bulk diffusional dissipation and boundary dissipation accompanying vacancy nucleation and absorption, are considered, but the latter is found to be negligible. For periodic arrangements of grains, diffusion formally decouples from elasticity but at the cost of a complicated boundary condition. The equilibrium of deviatorically stressed polycrystals is impossible without inclusion of interface energies. The secondary creep rate estimates correspond to the standard Nabarro-Herring model, and the volumetric creep is small. The initial (primary) creep rate is estimated to be much larger than the secondary creep rate.

  18. Triangles in a Lattice Parabola.

    ERIC Educational Resources Information Center

    Sastry, K. R. S.

    1991-01-01

    Discussed are properties possessed by polygons inscribed in the lattice parabola y=x, including the area of a triangle, triangles of minimum area, conditions for right triangles, triangles whose area is the cube of an integer, and implications of Pick's Theorem. Further directions to pursue are suggested. (MDH)

  19. Decompressive craniectomy with lattice duraplasty.

    PubMed

    Mitchell, P; Tseng, M; Mendelow, A D

    2004-02-01

    A method of opening dura for decompressive craniectomies is described. Numerous cuts intersecting in a lattice pattern allow the dura to expand in a gradual and controlled manner minimising the chances of cortical laceration or venous kinking on the craniectomy edge.

  20. Lattice QCD in Background Fields

    SciTech Connect

    William Detmold, Brian Tiburzi, Andre Walker-Loud

    2009-06-01

    Electromagnetic properties of hadrons can be computed by lattice simulations of QCD in background fields. We demonstrate new techniques for the investigation of charged hadron properties in electric fields. Our current calculations employ large electric fields, motivating us to analyze chiral dynamics in strong QED backgrounds, and subsequently uncover surprising non-perturbative effects present at finite volume.

  1. Confinement and lattice gauge theory

    SciTech Connect

    Creutz, M

    1980-06-01

    The motivation for formulating gauge theories on a lattice to study non-perturbative phenomena is reviewed, and recent progress supporting the compatibility of asymptotic freedom and quark confinement in the standard SU(3) Yang-Mills theory of the strong interaction is discussed.

  2. Spin-orbit-coupled fermions in an optical lattice clock

    NASA Astrophysics Data System (ADS)

    Kolkowitz, S.; Bromley, S. L.; Bothwell, T.; Wall, M. L.; Marti, G. E.; Koller, A. P.; Zhang, X.; Rey, A. M.; Ye, J.

    2017-02-01

    Engineered spin-orbit coupling (SOC) in cold-atom systems can enable the study of new synthetic materials and complex condensed matter phenomena. However, spontaneous emission in alkali-atom spin-orbit-coupled systems is hindered by heating, limiting the observation of many-body effects and motivating research into potential alternatives. Here we demonstrate that spin-orbit-coupled fermions can be engineered to occur naturally in a one-dimensional optical lattice clock. In contrast to previous SOC experiments, here the SOC is both generated and probed using a direct ultra-narrow optical clock transition between two electronic orbital states in 87Sr atoms. We use clock spectroscopy to prepare lattice band populations, internal electronic states and quasi-momenta, and to produce spin-orbit-coupled dynamics. The exceptionally long lifetime of the excited clock state (160 seconds) eliminates decoherence and atom loss from spontaneous emission at all relevant experimental timescales, allowing subsequent momentum- and spin-resolved in situ probing of the SOC band structure and eigenstates. We use these capabilities to study Bloch oscillations, spin-momentum locking and Van Hove singularities in the transition density of states. Our results lay the groundwork for using fermionic optical lattice clocks to probe new phases of matter.

  3. Spin–orbit-coupled fermions in an optical lattice clock

    NASA Astrophysics Data System (ADS)

    Kolkowitz, S.; Bromley, S. L.; Bothwell, T.; Wall, M. L.; Marti, G. E.; Koller, A. P.; Zhang, X.; Rey, A. M.; Ye, J.

    2016-12-01

    Engineered spin–orbit coupling (SOC) in cold-atom systems can enable the study of new synthetic materials and complex condensed matter phenomena. However, spontaneous emission in alkali-atom spin–orbit-coupled systems is hindered by heating, limiting the observation of many-body effects and motivating research into potential alternatives. Here we demonstrate that spin–orbit-coupled fermions can be engineered to occur naturally in a one-dimensional optical lattice clock. In contrast to previous SOC experiments, here the SOC is both generated and probed using a direct ultra-narrow optical clock transition between two electronic orbital states in 87Sr atoms. We use clock spectroscopy to prepare lattice band populations, internal electronic states and quasi-momenta, and to produce spin–orbit-coupled dynamics. The exceptionally long lifetime of the excited clock state (160 seconds) eliminates decoherence and atom loss from spontaneous emission at all relevant experimental timescales, allowing subsequent momentum- and spin-resolved in situ probing of the SOC band structure and eigenstates. We use these capabilities to study Bloch oscillations, spin–momentum locking and Van Hove singularities in the transition density of states. Our results lay the groundwork for using fermionic optical lattice clocks to probe new phases of matter.

  4. Chiral four-dimensional heterotic covariant lattices

    NASA Astrophysics Data System (ADS)

    Beye, Florian

    2014-11-01

    In the covariant lattice formalism, chiral four-dimensional heterotic string vacua are obtained from certain even self-dual lattices which completely decompose into a left-mover and a right-mover lattice. The main purpose of this work is to classify all right-mover lattices that can appear in such a chiral model, and to study the corresponding left-mover lattices using the theory of lattice genera. In particular, the Smith-Minkowski-Siegel mass formula is employed to calculate a lower bound on the number of left-mover lattices. Also, the known relationship between asymmetric orbifolds and covariant lattices is considered in the context of our classification.

  5. Modeling pions on the lattice

    NASA Astrophysics Data System (ADS)

    Cecile, D. J.

    In Quantum Chromodynamics (QCD), the pions are the lightest bound states. Current lattice QCD calculations are not able to study pions at realistic masses due to algorithmic difficulties. Instead, lattice studies are limited to unphysically large pion masses, and Chiral Perturbation Theory (ChPT) is often relied upon to extrapolate lattice results to the phenomenological regime and to the chiral limit, where quarks are massless. One of the outstanding problems in the field is to determine the range of quark masses where ChPT is valid and to understand the nonperturbative physics that may cause ChPT to break down. Given the difficulty of studying QCD, it is interesting and useful to construct a lattice field theory model of pions, which would allow a direct lattice calculation without the need for chiral extrapolations. This model can be used to evaluate the reliability of chiral extrapolations as applied to lattice data in the context of a lattice field theory that is exactly solvable numerically even at small quark masses and in the chiral limit. In this light, to create a model of pions of two-flavor Quantum Chromodynamics (QCD), a lattice field theory involving two flavors of staggered quarks interacting strongly with Abelian gauge fields is constructed. In the chiral limit, this theory exhibits a SUL(2) x SU R(2) x UA(1) symmetry. The UA(1) symmetry can be broken by introducing a four-fermion term into the action, thereby incorporating the physics of the QCD anomaly. To qualify as a meaningful model of QCD, this lattice model must exhibit spontaneous chiral symmetry breaking and confinement and must have a continuum limit. An interesting mechanism is introduced to address the continuum limit. In particular, an extra dimension allows one to tune a fictitious temperature in order to access a phase of broken symmetry and to find a range where the pion decay constant is much smaller than the lattice cutoff, i.e. Fpi ≪1a . Unlike lattice QCD, a major advantage of

  6. Lattice dynamics and lattice thermal conductivity of thorium dicarbide

    NASA Astrophysics Data System (ADS)

    Liao, Zongmeng; Huai, Ping; Qiu, Wujie; Ke, Xuezhi; Zhang, Wenqing; Zhu, Zhiyuan

    2014-11-01

    The elastic and thermodynamic properties of ThC2 with a monoclinic symmetry have been studied by means of density functional theory and direct force-constant method. The calculated properties including the thermal expansion, the heat capacity and the elastic constants are in a good agreement with experiment. Our results show that the vibrational property of the C2 dimer in ThC2 is similar to that of a free standing C2 dimer. This indicates that the C2 dimer in ThC2 is not strongly bonded to Th atoms. The lattice thermal conductivity for ThC2 was calculated by means of the Debye-Callaway model. As a comparison, the conductivity of ThC was also calculated. Our results show that the ThC and ThC2 contributions of the lattice thermal conductivity to the total conductivity are 29% and 17%, respectively.

  7. The channels of Mars

    NASA Technical Reports Server (NTRS)

    Baker, Victor R.

    1988-01-01

    The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

  8. The channels of Mars

    NASA Technical Reports Server (NTRS)

    Baker, Victor R.

    1988-01-01

    The geomorphology of Mars is discussed, focusing on the Martian channels. The great flood channels of Mars, the processes of channel erosion, and dendritic channel networks, are examined. The topography of the Channeled Scabland region of the northwestern U.S. is described and compared to the Martian channels. The importance of water in the evolution of the channel systems is considered.

  9. Lattice Boltzmann solver of Rossler equation

    NASA Astrophysics Data System (ADS)

    Yan, Guangwu; Ruan, Li

    2000-06-01

    We proposed a lattice Boltzmann model for the Rossler equation. Using a method of multiscales in the lattice Boltzmann model, we get the diffusion reaction as a special case. If the diffusion effect disappeared, we can obtain the lattice Boltzmann solution of the Rossler equation on the mesescopic scale. The numerical results show the method can be used to simulate Rossler equation.

  10. The CKM Matrix from Lattice QCD

    SciTech Connect

    Mackenzie, Paul B.; /Fermilab

    2009-07-01

    Lattice QCD plays an essential role in testing and determining the parameters of the CKM theory of flavor mixing and CP violation. Very high precisions are required for lattice calculations analyzing CKM data; I discuss the prospects for achieving them. Lattice calculations will also play a role in investigating flavor mixing and CP violation beyond the Standard Model.

  11. Long-Range Lattice-Gas Algorithm

    DTIC Science & Technology

    2007-11-02

    lattice-gases, and therefore inherits exact computabil- ity on a discrete spacetime lattice. Our contribution is the use of nonlocal interactions that...gases, and therefore inherits exact computability on a discrete spacetime lattice. Our contribution is the use of nonlocal interactions that allow us to

  12. Evidence for a bound H-dibaryon using lattice QCD

    SciTech Connect

    Will Detmold

    2012-04-01

    The H-dibaryon, a J = 0 state with the valence quark content udsuds, has long been hypothesized to exist because of the attractive nature of color magnetic gluon exchange in the flavor- singlet channel. Using lattice QCD the NPLQCD collaboration have investigated this system and evidence is presented for the existence of a stable H-dibaryon, albeit at a quark mass somewhat larger than that in nature. This calculation is reviewed and combined with subsequent calculations by the HALQCD collaboration at the SU(3) flavor symmetric point to identify bounds on the H-dibaryon mass at the physical quark masses.

  13. Partial lattice participation in the spin-lattice relaxation of potassium chromium alum

    NASA Astrophysics Data System (ADS)

    Overweg, J. A.; Flokstra, J.; ter Brake, H. J. M.; Gerritsma, G. J.

    1981-08-01

    We developed a SQUID-based frequency sweeping system for a.c. susceptibility measurements. Using this instrument we found that in Potassium Chromium Alum only a part of the lattice system is involved in the spin-lattice relaxation process. This partial lattice participation amounts 60-75% of the total lattice specific heat.

  14. Lattice gaugefixing and other optics in lattice gauge theory

    SciTech Connect

    Yee, Ken.

    1992-06-01

    We present results from four projects. In the first, quark and gluon propagators and effective masses and {Delta}I = 1/2 Rule operator matching coefficients are computed numerically in gaugefixed lattice QCD. In the second, the same quantities are evaluated analytically in the strong coupling, N {yields} {infinity} limit. In the third project, the Schwinger model is studied in covariant gauges, where we show that the effective electron mass varies with the gauge parameter and that longitudinal gaugefixing ambiguities affect operator product expansion coefficients (analogous to {Delta}I = 1/2 Rule matching coefficients) determined by matching gauge variant matrix elements. However, we find that matching coefficients even if shifted by the unphysical modes are {xi} invariant. In the fourth project, we show that the strong coupling parallelogram lattice Schwinger model as a different thermodynamic limit than the weak coupling continuum limit. As a function of lattice skewness angle these models span the {Delta} = {minus}1 critical line of 6-vertex models which, in turn, have been identified as c = 1 conformal field theories.

  15. Ion Channeling Analysis of Gallium Nitride Implanted with Deuterium

    SciTech Connect

    Myers, S.M.; Wampler, W.R.

    1998-12-23

    Ion channeling and transmission electron microscopy were used to examine the microstructure of GaN implanted with deuterium (D) at high (>1 at. %) and low (< 0.1 at. %) D concentrations. At high concentrations, bubbles and basal-plane stacking faults were observed. Ion channeling showed the D was disordered relative to the GaN lattice, consistent with precipitation of D2 into bubbles. At low D concentrations, bubbles and stacking faults are absent and ion channeling shows that a large fraction of the D occupies sites near the center of the c-axis channel.

  16. Small-angle electron scattering from magnetic artificial lattice.

    PubMed

    Takayanagi, Kazuya; Koyama, Tsukasa; Mori, Shigeo; Harada, Ken; Togawa, Yoshihiko

    2012-01-01

    In this study, quantitative reciprocal-space analyses of magnetic domain structures in magnetic artificial lattices of patterned elements were performed by means of the small-angle electron scattering (SAES) technique. Using a conventional transmission electron microscope with a LaB(6) thermal-emission electron gun, Lorentz deflection due to magnetic moments in patterned elements and Bragg diffraction due to the lattice periodicity are simultaneously recorded at an angle of the order of less than 1 10(-)(6) rad when using electron waves with high spatial coherency and large camera length. The present SAES technique together with TEM real-space imaging methods such as Lorentz microscopy will be useful in analyzing electromagnetic fields in nano-scaled materials.

  17. A unified model for two-lane lattice traffic flow

    NASA Astrophysics Data System (ADS)

    Wang, Yanhong

    2016-09-01

    In this paper, a unified model is presented for two-lane lattice traffic flow, with comparing different effects in the various lattice hydrodynamic models. Results of linear and nonlinear analysis show that multiple density difference effect (MDDE) is the strongest to enlarge the stable region in two-lane systems. Followed by density difference effect (DDE), multiple flux difference effect (MFDE), and finally flux difference effect (FDE). But when density is around 0.25, MFDE is better to enlarge the stable region than DDE. The reason is that a small flow-rate value might correspond to either a light traffic or a heavy traffic. Also energy consumption and traffic emissions are analyzed and shown to be the same marshaling sequence as linear and nonlinear analysis results. Numerical simulations validate theoretical analysis. And this is consistent with the realistic.

  18. Inverted Channels

    NASA Technical Reports Server (NTRS)

    2006-01-01

    23 June 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sinuous ridges and other landforms exposed by erosion in the Aeolis region of Mars. The ridges in this scene indicate the locations of ancient channels in a fan of sediment deposited in this region. Over time, wind erosion has removed surrounding materials and left the channels, which had been filled by sediment, standing as ridges.

    Location near: 4.5oS, 205.2oW Image width: 2 km (1.2 mi) Illumination from: upper left Season: Southern Autumn

  19. Channel drop filters in woodpile-heterostructures

    NASA Astrophysics Data System (ADS)

    Feng, Zhifang; Zhang, Dandan; Yasin Akhtar Raja, M.

    2014-02-01

    Channel drop-filter is essential building blocks of transceivers that are the workhorse of Gbps communication and enable the emerging 100 Gb/s technology. Using finite difference time domain method, heterostructures based channel drop filter in microwave region involving resonant system (in woodpile structure) are designed, analyzed, and simulated. Our simulations using hetero-woodpile-structures show that the resonant modes can be effectively adjusted in various ways, such as only changing the distance of two cavities or changing the lattice constants in the core woodpile. When bus/drop waveguides and resonant systems are located in different layers, we find that there is a resonant band.

  20. Starburst Channels

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies.

    In this example (figure 1) the channels form a 'starburst' pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out.

    Observation Geometry Image PSP_003443_0980 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 21-Apr-2007. The complete image is centered at -81.8 degrees latitude, 76.2 degrees East longitude. The range to the target site was 247.1 km (154.4 miles). At this distance the image scale is 24.7 cm/pixel (with 1 x 1 binning) so objects 74 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel. The image was taken at a local Mars time of 04:52 PM and the scene is illuminated from the west with a solar incidence angle of 71 degrees, thus the sun was about 19 degrees above the horizon. At a solar longitude of 223.4 degrees, the season on Mars is Northern Autumn.

  1. Starburst Channels

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] Figure 1

    Translucent carbon dioxide ice covers the polar regions of Mars seasonally. It is warmed and sublimates (evaporates) from below, and escaping gas carves a numerous channel morphologies.

    In this example (figure 1) the channels form a 'starburst' pattern, radiating out into feathery extensions. The center of the pattern is being buried with dust and new darker dust fans ring the outer edges. This may be an example of an expanding morphology, where new channels are formed as the older ones fill and are no longer efficiently channeling the subliming gas out.

    Observation Geometry Image PSP_003443_0980 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 21-Apr-2007. The complete image is centered at -81.8 degrees latitude, 76.2 degrees East longitude. The range to the target site was 247.1 km (154.4 miles). At this distance the image scale is 24.7 cm/pixel (with 1 x 1 binning) so objects 74 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel. The image was taken at a local Mars time of 04:52 PM and the scene is illuminated from the west with a solar incidence angle of 71 degrees, thus the sun was about 19 degrees above the horizon. At a solar longitude of 223.4 degrees, the season on Mars is Northern Autumn.

  2. Nonlinear channelizer.

    PubMed

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D; Leung, Daniel; Liu, Norman; Meadows, Brian K; Gordon, Frank; Bulsara, Adi R; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  3. Nonlinear channelizer

    NASA Astrophysics Data System (ADS)

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  4. Limiting vibration in space lattices

    SciTech Connect

    Midturi, S.

    1997-12-01

    Using finite-element analysis and other methods, engineers are evaluating ways to control the vibrations and extend the use of flexible, deployable structures in space. The exploration of the universe by the United States has led to many technological innovations for space travel. Among them are lightweight lattice structures and booms, which have been used on the Voyager probes to the outer planets, the Hubble space telescope,m and many other missions. Typical applications of lattice structures in space include instrument booms, antennae, and solar-array deployers and supports. Booms are designed for automatic deployment to a controlled length and retraction into a very compact stowage volume. Deployable solar booms are often subjected to severe vibration while in orbit, and vibration must be limited or completely eliminated for safe and satisfactory performance.

  5. Form factors from lattice QCD

    SciTech Connect

    Dru Renner

    2012-04-01

    Precision computation of hadronic physics with lattice QCD is becoming feasible. The last decade has seen precent-level calculations of many simple properties of mesons, and the last few years have seen calculations of baryon masses, including the nucleon mass, accurate to a few percent. As computational power increases and algorithms advance, the precise calculation of a variety of more demanding hadronic properties will become realistic. With this in mind, I discuss the current lattice QCD calculations of generalized parton distributions with an emphasis on the prospects for well-controlled calculations for these observables as well. I will do this by way of several examples: the pion and nucleon form factors and moments of the nucleon parton and generalized-parton distributions.

  6. Lattice QCD on nonorientable manifolds

    NASA Astrophysics Data System (ADS)

    Mages, Simon; Tóth, Bálint C.; Borsányi, Szabolcs; Fodor, Zoltán; Katz, Sándor D.; Szabó, Kálmán K.

    2017-05-01

    A common problem in lattice QCD simulations on the torus is the extremely long autocorrelation time of the topological charge when one approaches the continuum limit. The reason is the suppressed tunneling between topological sectors. The problem can be circumvented by replacing the torus with a different manifold, so that the connectivity of the configuration space is changed. This can be achieved by using open boundary conditions on the fields, as proposed earlier. It has the side effect of breaking translational invariance strongly. Here we propose to use a nonorientable manifold and show how to define and simulate lattice QCD on it. We demonstrate in quenched simulations that this leads to a drastic reduction of the autocorrelation time. A feature of the new proposal is that translational invariance is preserved up to exponentially small corrections. A Dirac fermion on a nonorientable manifold poses a challenge to numerical simulations: the fermion determinant becomes complex. We propose two approaches to circumvent this problem.

  7. Innovations in Lattice QCD Algorithms

    SciTech Connect

    Konstantinos Orginos

    2006-06-25

    Lattice QCD calculations demand a substantial amount of computing power in order to achieve the high precision results needed to better understand the nature of strong interactions, assist experiment to discover new physics, and predict the behavior of a diverse set of physical systems ranging from the proton itself to astrophysical objects such as neutron stars. However, computer power alone is clearly not enough to tackle the calculations we need to be doing today. A steady stream of recent algorithmic developments has made an important impact on the kinds of calculations we can currently perform. In this talk I am reviewing these algorithms and their impact on the nature of lattice QCD calculations performed today.

  8. The Fermilab lattice supercomputer project

    NASA Astrophysics Data System (ADS)

    Fischler, Mark; Atac, R.; Cook, A.; Deppe, J.; Gaines, I.; Husby, D.; Nash, T.; Pham, T.; Zmuda, T.; Hockney, George; Eichten, E.; Mackenzie, P.; Thacker, H. B.; Toussaint, D.

    1989-06-01

    The ACPMAPS system is a highly cost effective, local memory MIMD computer targeted at algorithm development and production running for gauge theory on the lattice. The machine consists of a compound hypercube of crates, each of which is a full crossbar switch containing several processors. The processing nodes are single board array processors based on the Weitek XL chip set, each with a peak power of 20 MFLOPS and supported by 8MBytes of data memory. The system currently being assembled has a peak power of 5 GFLOPS, delivering performance at approximately $250/MFLOP. The system is programmable in C and Fortran. An underpinning of software routines (CANOPY) provides an easy and natural way of coding lattice problems, such that the details of parallelism, and communication and system architecture are transparent to the user. CANOPY can easily be ported to any single CPU or MIMD system which supports C, and allows the coding of typical applications with very little effort.

  9. Tracking the SSC test lattices

    SciTech Connect

    Leemann, B.T.; Douglas, D.R.; Forest, E.

    1990-01-01

    The dynamic aperture and its determination emerged from the SSC reference design study as the single most important accelerator physics issue pertinent to the SSC. Beside the fundamental need of a finite dynamic aperture for any accelerator, it was considered to be a useful criterion for the magnet selection. An aperture workshop organized in November 1984 at LBL served the purpose to identify the various aspects of the aperture question and to organize the aperture task force accordingly. It was recognized that numerical models had to play an important role and the qualifications of several tracking codes were investigated. None of the existing codes could meet all of the criteria for an ideal tracking code and substantial program development became unavoidable. It was therefore decided to begin tracking SSC test lattices, which were provided by the aperture task force's lattice group and are described in an other paper to this conference, with existing tracking programs. 6 refs., 5 figs., 2 tabs.

  10. Fluctuating multicomponent lattice Boltzmann model.

    PubMed

    Belardinelli, D; Sbragaglia, M; Biferale, L; Gross, M; Varnik, F

    2015-02-01

    Current implementations of fluctuating lattice Boltzmann equations (FLBEs) describe single component fluids. In this paper, a model based on the continuum kinetic Boltzmann equation for describing multicomponent fluids is extended to incorporate the effects of thermal fluctuations. The thus obtained fluctuating Boltzmann equation is first linearized to apply the theory of linear fluctuations, and expressions for the noise covariances are determined by invoking the fluctuation-dissipation theorem directly at the kinetic level. Crucial for our analysis is the projection of the Boltzmann equation onto the orthonormal Hermite basis. By integrating in space and time the fluctuating Boltzmann equation with a discrete number of velocities, the FLBE is obtained for both ideal and nonideal multicomponent fluids. Numerical simulations are specialized to the case where mean-field interactions are introduced on the lattice, indicating a proper thermalization of the system.

  11. A transportable optical lattice clock

    NASA Astrophysics Data System (ADS)

    Vogt, Stefan; Häfner, Sebastian; Grotti, Jacopo; Koller, Silvio; Al-Masoudi, Ali; Sterr, Uwe; Lisdat, Christian

    2016-06-01

    We present the experimental setup and first results of PTB's transportable 87Sr clock. It consists of a physics package, several compact laser breadboards, and a transportable high finesse cavity for the clock laser. A comparison of the transportable system with our stationary optical lattice clock yields an instability of 2.2 x 10-15 √s/τ for the transportable clock. The current fractional uncertainty of 1 × 10-15 is still limited by the not yet fully evaluated light shift from the free running optical lattice laser operated near the magic wavelength. We are currently improving our transportable system to reach an uncertainty at or below the 10-17 level, which will finaly be limited by the uncertainty in blackbody radiation shift correction.

  12. LATTICE QCD AT FINITE DENSITY.

    SciTech Connect

    SCHMIDT, C.

    2006-07-23

    I discuss different approaches to finite density lattice QCD. In particular, I focus on the structure of the phase diagram and discuss attempts to determine the location of the critical end-point. Recent results on the transition line as function of the chemical potential (T{sub c}({mu}{sub q})) are reviewed. Along the transition line, hadronic fluctuations have been calculated; which can be used to characterize properties of the Quark Gluon plasma and eventually can also help to identify the location of the critical end-point in the QCD phase diagram on the lattice and in heavy ion experiments. Furthermore, I comment on the structure of the phase diagram at large {mu}{sub q}.

  13. Scattering in Quantum Lattice Gases

    NASA Astrophysics Data System (ADS)

    O'Hara, Andrew; Love, Peter

    2009-03-01

    Quantum Lattice Gas Automata (QLGA) are of interest for their use in simulating quantum mechanics on both classical and quantum computers. QLGAs are an extension of classical Lattice Gas Automata where the constraint of unitary evolution is added. In the late 1990s, David A. Meyer as well as Bruce Boghosian and Washington Taylor produced similar models of QLGAs. We start by presenting a unified version of these models and study them from the point of view of the physics of wave-packet scattering. We show that the Meyer and Boghosian-Taylor models are actually the same basic model with slightly different parameterizations and limits. We then implement these models computationally using the Python programming language and show that QLGAs are able to replicate the analytic results of quantum mechanics (for example reflected and transmitted amplitudes for step potentials and the Klein paradox).

  14. Lattice Simulations and Infrared Conformality

    DOE PAGES

    Appelquist, Thomas; Fleming, George T.; Lin, Meifeng; ...

    2011-09-01

    We examine several recent lattice-simulation data sets, asking whether they are consistent with infrared conformality. We observe, in particular, that for an SU(3) gauge theory with 12 Dirac fermions in the fundamental representation, recent simulation data can be described assuming infrared conformality. Lattice simulations include a fermion mass m which is then extrapolated to zero, and we note that this data can be fit by a small-m expansion, allowing a controlled extrapolation. We also note that the conformal hypothesis does not work well for two theories that are known or expected to be confining and chirally broken, and that itmore » does work well for another theory expected to be infrared conformal.« less

  15. Studying and applying channeling at extremely high bunch charges

    SciTech Connect

    Carrigan, R.A.; /Fermilab

    2005-01-01

    The potentially high plasma densities possible in solids might produce extremely high acceleration gradients. However solid-state plasmas could pose daunting challenges. Crystal channeling has been suggested as a mechanism to ameliorate these problems. A high-density plasma in a crystal lattice could quench the channeling process. There is no experimental or theoretical guidance on channeling for intense charged particle beams. An experiment has been carried out at the Fermilab A0 photoinjector to observe electron channeling radiation at high bunch charges. An electron beam with up to 8 nC per electron bunch was used to investigate the electron-crystal interaction. No evidence was found of quenching of channeling at charge densities two orders of magnitude larger than in earlier experiments. Possible new channeling experiments are discussed for the much higher bunch charge densities and shorter times required to probe channeling breakdown and plasma behavior.

  16. Apiary B Factory Lattice Design

    SciTech Connect

    Donald, M.H.R.; Garren, A.A.

    1991-05-03

    The Apiary B Factory is a proposed high-intensity electron-positron collider. This paper presents the lattice design for this facility, which envisions two rings with unequal energies in the PEP tunnel. The design has many interesting optical and geometrical features due to the needs to conform to the existing tunnel, and to achieve the necessary emittances, damping times and vacuum. Existing hardware is used to a maximum extent.

  17. Apiary B Factory lattice design

    SciTech Connect

    Donald, M.H.R. ); Garren, A.A. )

    1991-04-01

    The Apiary B Factory is a proposed high-intensity electron-positron collider. This paper will present the lattice design for this facility, which envisions two rings with unequal energies in the PEP tunnel. The design has many interesting optical and geometrical features due to the needs to conform to the existing tunnel, and to achieve the necessary emittances, damping times and vacuum. Existing hardware is used to a maximum extent. 8 figs. 1 tab.

  18. Hadron physics from lattice QCD

    NASA Astrophysics Data System (ADS)

    Bietenholz, Wolfgang

    2016-07-01

    We sketch the basic ideas of the lattice regularization in Quantum Field Theory, the corresponding Monte Carlo simulations, and applications to Quantum Chromodynamics (QCD). This approach enables the numerical measurement of observables at the non-perturbative level. We comment on selected results, with a focus on hadron masses and the link to Chiral Perturbation Theory. At last, we address two outstanding issues: topological freezing and the sign problem.

  19. Scanning phononic lattices with ultrasound

    SciTech Connect

    Vines, R.E.; Wolfe, J.P.; Every, A.V.

    1999-11-01

    A method for probing the elastic properties of newly developed periodic structures using acoustic waves is introduced. Highly anisotropic transmission of surface acoustic waves is observed by continuously scanning the wave vector angle. Preliminary models of wave propagation through multilayers and two-dimensional lattices explain some of the experimental features, while other features can be attributed to the resonant excitation of interface waves. {copyright} {ital 1999} {ital The American Physical Society}

  20. Fuzzy lattice neurocomputing (FLN) models.

    PubMed

    Kaburlasos, V G; Petridis, V

    2000-12-01

    In this work it is shown how fuzzy lattice neurocomputing (FLN) emerges as a connectionist paradigm in the framework of fuzzy lattices (FL-framework) whose advantages include the capacity to deal rigorously with: disparate types of data such as numeric and linguistic data, intervals of values, 'missing' and 'don't care' data. A novel notation for the FL-framework is introduced here in order to simplify mathematical expressions without losing content. Two concrete FLN models are presented, namely 'sigma-FLN' for competitive clustering, and 'FLN with tightest fits (FLNtf)' for supervised clustering. Learning by the sigma-FLN, is rapid as it requires a single pass through the data, whereas learning by the FLNtf, is incremental, data order independent, polynomial theta(n3), and it guarantees maximization of the degree of inclusion of an input in a learned class as explained in the text. Convenient geometric interpretations are provided. The sigma-FLN is presented here as fuzzy-ART's extension in the FL-framework such that sigma-FLN widens fuzzy-ART's domain of application to (mathematical) lattices by augmenting the scope of both of fuzzy-ART's choice (Weber) and match functions, and by enhancing fuzzy-ART's complement coding technique. The FLNtf neural model is applied to four benchmark data sets of various sizes for pattern recognition and rule extraction. The benchmark data sets in question involve jointly numeric and nominal data with 'missing' and/or 'don't care' attribute values, whereas the lattices involved include the unit-hypercube, a probability space, and a Boolean algebra. The potential of the FL-framework in computing is also delineated.

  1. Optical emission spectrometric determination of arsenic and antimony by continuous flow chemical hydride generation and a miniaturized microwave microstrip argon plasma operated inside a capillary channel in a sapphire wafer

    NASA Astrophysics Data System (ADS)

    Pohl, Pawel; Zapata, Israel Jimenéz; Bings, Nicolas H.; Voges, Edgar; Broekaert, José A. C.

    2007-05-01

    Continuous flow chemical hydride generation coupled directly to a 40 W, atmospheric pressure, 2.45 GHz microwave microstrip Ar plasma operated inside a capillary channel in a sapphire wafer has been optimized for the emission spectrometric determination of As and Sb. The effect of the NaBH 4 concentration, the concentration of HCl, HNO 3 and H 2SO 4 used for sample acidification, the Ar flow rate, the reagent flow rates, the liquid volume in the separator as well as the presence of interfering metals such as Fe, Cu, Ni, Co, Zn, Cd, Mn, Pb and Cr, was investigated in detail. A considerable influence of Fe(III) (enhancement of up to 50 %) for As(V) and of Fe(III), Cu(II) and Cr(III) (suppression of up to 75%) as well as of Cd(II) and Mn(II) (suppression by up to 25%) for Sb(III) was found to occur, which did not change by more than a factor of 2 in the concentration range of 2-20 μg ml - 1 . The microstrip plasma tolerated the introduction of 4.2 ml min - 1 of H 2 in the Ar working gas, which corresponded to an H 2/Ar ratio of 28%. Under these conditions, the excitation temperature as measured with Ar atom lines and the electron number density as determined from the Stark broadening of the H β line was of the order of 5500 K and 1.50 · 10 14 cm - 3 , respectively. Detection limits (3σ) of 18 ng ml - 1 for As and 31 ng ml - 1 for Sb were found and the calibration curves were linear over 2 orders of magnitude. With the procedure developed As and Sb could be determined at the 45 and 6.4 μg ml - 1 level in a galvanic bath solution containing 2.5% of NiSO 4. Additionally, As was determined in a coal fly ash reference material (NIST SRM 1633a) with a certified concentration of As of 145 ± 15 μg g - 1 and a value of 144 ± 4 μg g - 1 was found.

  2. Nuclear reactions from lattice QCD

    DOE PAGES

    Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.

    2015-01-13

    In this study, one of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculationsmore » of some of the low-energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.« less

  3. Nuclear reactions from lattice QCD

    SciTech Connect

    Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.

    2015-01-13

    In this study, one of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low-energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.

  4. Quantised vortices in polariton lattices

    NASA Astrophysics Data System (ADS)

    Berloff, Natalia

    2015-11-01

    The first comprehensive treatment of quantised vorticity in the light of research on vortices in modern fluid mechanics appeared in Russell Donnelly seminal research papers and summarized in his 1991 book ``Quantized Vortices in Helium II''. Recently quantized vortices have been studied in polariton condensates. Polaritons are the mixed light-matter quasi-particles that are formed in the strong exciton-photon coupling regime. Under non-resonant optical excitation rapid relaxation of carriers and bosonic stimulation result in the formation of a non-equilibrium polariton condensate characterized by a single many-body wave-function, therefore, naturally possessing quantized vortices. Polariton condensates can be imprinted into any two-dimensional lattice by spatial modulation of the pumping laser and form vortices via interacting outfows from the pumping sites. Optically pumped polariton condensates can be injected in lattice configurations with arbitrary density profiles offering the possibility to control the kinetics of the condensate and therefore the number and location of vortices. I will present some new developments in theoretical and experimental studies of quantized vortices in polariton condensates and discuss possible practical implementations of polariton lattices.

  5. Ectopic A-lattice seams destabilize microtubules.

    PubMed

    Katsuki, Miho; Drummond, Douglas R; Cross, Robert A

    2014-01-01

    Natural microtubules typically include one A-lattice seam within an otherwise helically symmetric B-lattice tube. It is currently unclear how A-lattice seams influence microtubule dynamic instability. Here we find that including extra A-lattice seams in GMPCPP microtubules, structural analogues of the GTP caps of dynamic microtubules, destabilizes them, enhancing their median shrinkage rate by >20-fold. Dynamic microtubules nucleated by seeds containing extra A-lattice seams have growth rates similar to microtubules nucleated by B-lattice seeds, yet have increased catastrophe frequencies at both ends. Furthermore, binding B-lattice GDP microtubules to a rigor kinesin surface stabilizes them against shrinkage, whereas microtubules with extra A-lattice seams are stabilized only slightly. Our data suggest that introducing extra A-lattice seams into dynamic microtubules destabilizes them by destabilizing their GTP caps. On this basis, we propose that the single A-lattice seam of natural B-lattice MTs may act as a trigger point, and potentially a regulation point, for catastrophe.

  6. Ectopic A-lattice seams destabilize microtubules

    PubMed Central

    Katsuki, Miho; Drummond, Douglas R.; Cross, Robert A.

    2014-01-01

    Natural microtubules typically include one A-lattice seam within an otherwise helically symmetric B-lattice tube. It is currently unclear how A-lattice seams influence microtubule dynamic instability. Here we find that including extra A-lattice seams in GMPCPP microtubules, structural analogues of the GTP caps of dynamic microtubules, destabilizes them, enhancing their median shrinkage rate by >20-fold. Dynamic microtubules nucleated by seeds containing extra A-lattice seams have growth rates similar to microtubules nucleated by B-lattice seeds, yet have increased catastrophe frequencies at both ends. Furthermore, binding B-lattice GDP microtubules to a rigor kinesin surface stabilizes them against shrinkage, whereas microtubules with extra A-lattice seams are stabilized only slightly. Our data suggest that introducing extra A-lattice seams into dynamic microtubules destabilizes them by destabilizing their GTP caps. On this basis, we propose that the single A-lattice seam of natural B-lattice MTs may act as a trigger point, and potentially a regulation point, for catastrophe. PMID:24463734

  7. Lattice Truss Structural Response Using Energy Methods

    NASA Technical Reports Server (NTRS)

    Kenner, Winfred Scottson

    1996-01-01

    A deterministic methodology is presented for developing closed-form deflection equations for two-dimensional and three-dimensional lattice structures. Four types of lattice structures are studied: beams, plates, shells and soft lattices. Castigliano's second theorem, which entails the total strain energy of a structure, is utilized to generate highly accurate results. Derived deflection equations provide new insight into the bending and shear behavior of the four types of lattices, in contrast to classic solutions of similar structures. Lattice derivations utilizing kinetic energy are also presented, and used to examine the free vibration response of simple lattice structures. Derivations utilizing finite element theory for unique lattice behavior are also presented and validated using the finite element analysis code EAL.

  8. Finite temperature mechanical instability in disordered lattices

    NASA Astrophysics Data System (ADS)

    Zhang, Leyou; Mao, Xiaoming

    Mechanical instability takes different forms in various ordered and disordered systems, and little is known about how thermal fluctuations affect different classes of mechanical instabilities. We develop an analytic theory involving renormalization of rigidity and coherent potential approximation that can be used to understand finite-temperature mechanical stabilities in various disordered systems. We used this theory to study two disordered lattices: randomly diluted triangular lattice and randomly braced square lattice. These two lattices belong to two different universality classes as they approach mechanical instability at T = 0 . We show that thermal fluctuations stabilize both lattices. In particular, the triangular lattice displays a critical regime in which the shear modulus scales as G ~T 1 / 2 , whereas the square lattice shows G ~T 2 / 3 . We discuss generic scaling laws for finite T mechanical instabilities and relate to experimental systems including jamming and glass transitions.

  9. Dicke superradiance as nondestructive probe for the state of atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Brinke, Nicolai ten; Schützhold, Ralf

    2016-05-01

    We present a proposal for a probing scheme utilizing Dicke superradiance to obtain information about ultracold atoms in optical lattices. A probe photon is absorbed collectively by an ensemble of lattice atoms generating a Dicke state. The lattice dynamics (e.g., tunneling) affects the coherence properties of that Dicke state and thus alters the superradiant emission characteristics - which in turn provides insight into the lattice (dynamics). Comparing the Bose-Hubbard and the Fermi-Hubbard model, we find similar superradiance in the strongly interacting Mott insulator regime, but crucial differences in the weakly interacting (superfluid or metallic) phase. Furthermore, we study the possibility to detect whether a quantum phase transition between the two regimes can be considered adiabatic or a quantum quench.

  10. Dynamic Channel Allocation

    DTIC Science & Technology

    2003-09-01

    7 1 . Fixed Channel Allocation (FCA) ........................................................7 2. Dynamic Channel ...19 7. CSMA/CD-Based Multiple Network Lines .....................................20 8. Hybrid Channel Allocation in Wireless Networks...28 1 . Channel Allocation

  11. Induced resonance evolution of the channeling electron beam

    NASA Astrophysics Data System (ADS)

    Ambartsumov, Vazgen V.; Kalashnikov, Nikolay P.

    2017-07-01

    The motion of channeling particles in the accompanying coordinate system can be considered as one-dimensional oscillator (in the case of planar channeling) or as a two-dimensional atom (in the case of axial channeling) (Lindhard, 1965; Baryshevskii, 1982; Vorobiev, 1984; Kalashnikov, 1988; Ryabov, 1994). The transversal motion of the channeling particles is characterized by discrete spectrum. The occupation probability of the transversal motion levels depends on the entrance angle of charged particle relative to the crystallographic axis. Passing through the single crystal the charged channeling particle undergoes periodic impact of the lattice atoms (Kalashnikov, 1988; Foot, 2005; Ter-Mikaelyan, 1972; Okorokov et al., 1973) with the main frequency ω = 2 πv/d γ , where d is the lattice constant, v and γ = E/mc2 are the speed and the Lorentz-factor of the channeling particles (Kalashnikov, 1988). If an external periodic action frequency coincides with the transition frequency of the channeling particles from one quantized state of transversal motion in another, then the resonant excitation of channeling particles is possible. This effect is analogous with the excitation of the atomic electrons by the periodic field of monochromatic electromagnetic waves (Ter-Mikaelyan, 1972; Okorokov et al., 1973; Ohtsuki, 1983). The resonance conditions are discussed and the dependence of the occupation probability of the transversal motion levels of the channeling particles (electrons) upon the single crystal thickness is analyzed.

  12. Positron emission tomography wrist detector

    DOEpatents

    Schlyer, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois

    2006-08-15

    A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal representing a time-of-occurrence of an annihilation event, generating an address signal representing a channel detecting the annihilation event, and generating a channel signal including the time and address signals. The method also includes generating a composite signal including the channel signal and another similarly generated channel signal concerning another annihilation event. An apparatus that serially transfers annihilation information includes a time signal generator, address signal generator, channel signal generator, and composite signal generator. The time signal is asynchronous and the address signal is synchronous to a clock signal. A PET scanner includes a scintillation array, detection array, front-end array, and a serial encoder. The serial encoders include the time signal generator, address signal generator, channel signal generator, and composite signal generator.

  13. Calculation of Helium nuclei in quenched lattice QCD

    SciTech Connect

    Yamazaki, T.; Kuramashi, Y.; Ukawa, A.

    2011-10-24

    We present results for the binding energies for {sup 4}He and {sup 3}He nuclei calculated in quenched lattice QCD at the lattice spacing of a = 0.128 fm with a heavy quark mass corresponding to m{sub {pi}} = 0.8 GeV. Enormous computational cost for the nucleus correlation functions is reduced by avoiding redundancy of equivalent contractions stemming from permutation symmetry of protons or neutrons in the nucleus and various other symmetries. To distinguish a bound state from an attractive scattering state, we investigate the volume dependence of the energy difference between the ground state of the nucleus channel and the free multi-nucleon state by changing the spatial extent of the lattice from 3.1 fm to 12.3 fm. A finite energy difference left in the infinite spatial volume limit leads to the conclusion that the measured ground states are bounded. It is also encouraging that the measured binding energies and the experimental ones show the same order of magnitude.

  14. Lattice-assisted proton hopping in oxides at low temperatures

    NASA Astrophysics Data System (ADS)

    Samgin, A. L.

    2013-12-01

    Stimulated diffusion of protons in oxides such as ABO3 crystals and rutile TiO2 is discussed in the context of quantum Brownian motion. A self-consistent lattice-assisted proton hopping (LAPH) model is developed by going from white noise (characteristic of the standard stochastic theory of superionic conduction) to colored noise in the Markovian limit. This model differs from the commonly used ion jump models in that the hydrogen diffusion rate prefactor is identified as a quantity proportional to the frequency of phonon assistance. Application of the quantum fluctuation-dissipation theorem suggests that the dynamic activation energy for diffusion is a function of a bath-mode frequency. The LAPH model can predict enhanced rates of barrier jumping at room temperature compared to thermally activated proton diffusion. This indicates that low-temperature solid oxide devices are potential candidates for use in hydrogen energy research. The LAPH model offers a valid explanation for the mechanism of high protonic mobility recently observed for TiO2 in a picosecond transient pump-probe experiment. This unexpected dominant lattice relaxation channel must be considered as a new classical-like (but low-temperature) proton transfer mechanism. For vibration-assisted protonic jumps to occur at low temperature, the phonon assistance must be classified as a low-frequency vibration specific to each lattice.

  15. Analysis of transport of collimated radiation in a participating media using the lattice Boltzmann method

    NASA Astrophysics Data System (ADS)

    Mishra, Subhash C.; Vernekar, Rohan Ranganath

    2012-11-01

    Application of the lattice Boltzmann method (LBM) recently proposed by Asinari et al. [Asinari P, Mishra SC, Borchiellini R. A lattice Boltzmann formulation to the analysis of radiative heat transfer problems in a participating medium. Numer Heat Transfer B 2010; 57:126-146] is extended to the analysis of transport of collimated radiation in a planar participating medium. To deal with azimuthally symmetric radiation in planar medium, a new lattice structure for the LBM is used. The transport of the collimated component in the medium is analysed by two different, viz., flux splitting and direct approaches. For different angles of incidence of the collimated radiation, the LBM formulation is tested for the effects of the extinction coefficient, the anisotropy factor, and the boundary emissivities on heat flux and emissive power distributions. Results are compared with the benchmark results obtained using the finite volume method. Both the approaches in LBM provide accurate results.

  16. Emissions Inventory

    EPA Pesticide Factsheets

    This page describes the role of emission inventories in the air quality management process, a description of how emission inventories are developed, and where U.S. emission inventory information can be found.

  17. Topological magnon bands in ferromagnetic star lattice

    NASA Astrophysics Data System (ADS)

    Owerre, S. A.

    2017-05-01

    The experimental observation of topological magnon bands and thermal Hall effect in a kagomé lattice ferromagnet Cu(1-3, bdc) has inspired the search for topological magnon effects in various insulating ferromagnets that lack an inversion center allowing a Dzyaloshinskii-Moriya (DM) spin-orbit interaction. The star lattice (also known as the decorated honeycomb lattice) ferromagnet is an ideal candidate for this purpose because it is a variant of the kagomé lattice with additional links that connect the up-pointing and down-pointing triangles. This gives rise to twice the unit cell of the kagomé lattice, and hence more interesting topological magnon effects. In particular, the triangular bridges on the star lattice can be coupled either ferromagnetically or antiferromagnetically which is not possible on the kagomé lattice ferromagnets. Here, we study DM-induced topological magnon bands, chiral edge modes, and thermal magnon Hall effect on the star lattice ferromagnet in different parameter regimes. The star lattice can also be visualized as the parent material from which topological magnon bands can be realized for the kagomé and honeycomb lattices in some limiting cases.

  18. Unbiased sampling of lattice Hamilton path ensembles

    NASA Astrophysics Data System (ADS)

    Mansfield, Marc L.

    2006-10-01

    Hamilton paths, or Hamiltonian paths, are walks on a lattice which visit each site exactly once. They have been proposed as models of globular proteins and of compact polymers. A previously published algorithm [Mansfield, Macromolecules 27, 5924 (1994)] for sampling Hamilton paths on simple square and simple cubic lattices is tested for bias and for efficiency. Because the algorithm is a Metropolis Monte Carlo technique obviously satisfying detailed balance, we need only demonstrate ergodicity to ensure unbiased sampling. Two different tests for ergodicity (exact enumeration on small lattices, nonexhaustive enumeration on larger lattices) demonstrate ergodicity unequivocally for small lattices and provide strong support for ergodicity on larger lattices. Two other sampling algorithms [Ramakrishnan et al., J. Chem. Phys. 103, 7592 (1995); Lua et al., Polymer 45, 717 (2004)] are both known to produce biases on both 2×2×2 and 3×3×3 lattices, but it is shown here that the current algorithm gives unbiased sampling on these same lattices. Successive Hamilton paths are strongly correlated, so that many iterations are required between statistically independent samples. Rules for estimating the number of iterations needed to dissipate these correlations are given. However, the iteration time is so fast that the efficiency is still very good except on extremely large lattices. For example, even on lattices of total size 10×10×10 we are able to generate tens of thousands of uncorrelated Hamilton paths per hour of CPU time.

  19. Topological magnon bands in ferromagnetic star lattice.

    PubMed

    Owerre, S A

    2017-05-10

    The experimental observation of topological magnon bands and thermal Hall effect in a kagomé lattice ferromagnet Cu(1-3, bdc) has inspired the search for topological magnon effects in various insulating ferromagnets that lack an inversion center allowing a Dzyaloshinskii-Moriya (DM) spin-orbit interaction. The star lattice (also known as the decorated honeycomb lattice) ferromagnet is an ideal candidate for this purpose because it is a variant of the kagomé lattice with additional links that connect the up-pointing and down-pointing triangles. This gives rise to twice the unit cell of the kagomé lattice, and hence more interesting topological magnon effects. In particular, the triangular bridges on the star lattice can be coupled either ferromagnetically or antiferromagnetically which is not possible on the kagomé lattice ferromagnets. Here, we study DM-induced topological magnon bands, chiral edge modes, and thermal magnon Hall effect on the star lattice ferromagnet in different parameter regimes. The star lattice can also be visualized as the parent material from which topological magnon bands can be realized for the kagomé and honeycomb lattices in some limiting cases.

  20. Channeling technique to make nanoscale ion beams

    NASA Astrophysics Data System (ADS)

    Biryukov, V. M.; Bellucci, S.; Guidi, V.

    2005-04-01

    Particle channeling in a bent crystal lattice has led to an efficient instrument for beam steering at accelerators [Biryukov et al., Crystal Channeling and its Application at High Energy Accelerators, Springer, Berlin, 1997], demonstrated from MeV to TeV energies. In particular, crystal focusing of high-energy protons to micron size has been demonstrated at IHEP with the results well in match with Lindhard (critical angle) prediction. Channeling in crystal microstructures has been proposed as a unique source of a microbeam of high-energy particles [Bellucci et al., Phys. Rev. ST Accel. Beams 6 (2003) 033502]. Channeling in nanostructures (single-wall and multi-wall nanotubes) offers the opportunities to produce ion beams on nanoscale. Particles channeled in a nanotube (with typical diameter of about 1 nm) are trapped in two dimensions and can be steered (deflected, focused) with the efficiency similar to that of crystal channeling or better. This technique has been a subject of computer simulations, with experimental efforts under way in several high-energy labs, including IHEP. We present the theoretical outlook for making channeling-based nanoscale ion beams and report the experience with crystal-focused microscale proton beams.

  1. Collisional Losses, Decoherence, and Frequency Shifts in Optical Lattice Clocks with Bosons

    SciTech Connect

    Lisdat, Ch.; Winfred, J. S. R. Vellore; Middelmann, T.; Riehle, F.; Sterr, U.

    2009-08-28

    We have quantified collisional losses, decoherence and the collision shift in a one-dimensional optical lattice clock on the highly forbidden transition {sup 1}S{sub 0}-{sup 3}P{sub 0} at 698 nm with bosonic {sup 88}Sr. We were able to distinguish two loss channels: inelastic collisions between atoms in the upper and lower clock state and atoms in the upper clock state only. Based on the measured coefficients, we determine the operation parameters at which a 1D-lattice clock with {sup 88}Sr shows no degradation due to collisions on the fractional uncertainty level of 10{sup -16}.

  2. Rho Meson Decay into pi+pi- on Asymmetrical Lattices

    NASA Astrophysics Data System (ADS)

    Pelissier, Craig S.

    The computation of the lowest-lying hadron masses was the earliest success of lattice QCD. Current spectroscopy is faced with the task of computing excited-states. This is particularly challenging when excited-states appear as scattering resonances. In this case, the resonance parameters have to be determined by studying the energies of the scattering states. Currently it is only computationally feasible to compute resonances of the simplest systems. In our work, we carry out a calculation of the ρ(770) resonance seen in the isospin l = 1 two-pion system in the l = 1 channel. To determine the resonance parameters, we compute the scattering phase shifts from the two-pion spectrum using Luscher's formula. Unlike other studies which employ the moving frame formalism, we use lattices with one spatial direction elongated. To vary the momentum of the two-pion state, we adjust the length of the elongated direction. With this approach, the two-pion momentum can be tuned more finely, which allows one to map out the resonance more accurately. In this work, we employed nHYP-smeared clover fermions with two mass-degenerate quarks. The lattice computations were carried out on large elongated lattices with spatial volumes ≥ 33 fm3. We carried out an exploratory quenched study and found the two-pion spectrum to be compatible with the results obtained using dynamical fermions. Our results showed a disagreement with the physical decay at the level of 20% which is typical for quenched simulations. After completing the quenched study, we recomputed the resonance parameters on fully dynamical gauge configurations with a pion mass of 304(2) MeV. We found a value mρ = 827(3)(5) MeV and gρππ = 6.67(42) for the resonance mass and coupling constant. Our results are consistent with other lattice studies at similar pion masses and are in good agreement with the prediction from unitarized Chiral Perturbation Theory at NLO. The scattering phase shifts we computed are more evenly

  3. Fractional random walk lattice dynamics

    NASA Astrophysics Data System (ADS)

    Michelitsch, T. M.; Collet, B. A.; Riascos, A. P.; Nowakowski, A. F.; Nicolleau, F. C. G. A.

    2017-02-01

    We analyze time-discrete and time-continuous ‘fractional’ random walks on undirected regular networks with special focus on cubic periodic lattices in n  =  1, 2, 3,.. dimensions. The fractional random walk dynamics is governed by a master equation involving fractional powers of Laplacian matrices {{L}\\fracα{2}}} where α =2 recovers the normal walk. First we demonstrate that the interval 0<α ≤slant 2 is admissible for the fractional random walk. We derive analytical expressions for the transition matrix of the fractional random walk and closely related the average return probabilities. We further obtain the fundamental matrix {{Z}(α )} , and the mean relaxation time (Kemeny constant) for the fractional random walk. The representation for the fundamental matrix {{Z}(α )} relates fractional random walks with normal random walks. We show that the matrix elements of the transition matrix of the fractional random walk exihibit for large cubic n-dimensional lattices a power law decay of an n-dimensional infinite space Riesz fractional derivative type indicating emergence of Lévy flights. As a further footprint of Lévy flights in the n-dimensional space, the transition matrix and return probabilities of the fractional random walk are dominated for large times t by slowly relaxing long-wave modes leading to a characteristic {{t}-\\frac{n{α}} -decay. It can be concluded that, due to long range moves of fractional random walk, a small world property is emerging increasing the efficiency to explore the lattice when instead of a normal random walk a fractional random walk is chosen.

  4. One-dimensional lattices topologically equivalent to three-dimensional lattices within the context of the lattice gas model

    NASA Astrophysics Data System (ADS)

    Costanza, E. F.; Costanza, G.

    2017-09-01

    Continuum partial differential equations are obtained from a set of discrete stochastic evolution equations of both non-Markovian and Markovian processes and applied to the diffusion on a cubic lattice within the context of the lattice gas model. A procedure allowing to construct one-dimensional lattices that are topologically equivalent to a cubic three-dimensional lattice is described in detail using a successive ;unfolding; process. This example shows some new features that possess the procedure and extensions are also suggested in order to provide some another uses of the present approach.

  5. Casimir effect for Dirac lattices

    NASA Astrophysics Data System (ADS)

    Bordag, M.; Pirozhenko, I. G.

    2017-03-01

    We consider polarizable sheets, which recently received some attention, especially in the context of the dispersion interaction of thin sheets like graphene. These sheets are modeled by a collection of delta function potentials and resemble zero-range potentials, which are known in quantum mechanics. We develop a theoretical description and apply the so-called TGTG formula to calculate the interaction of two such lattices. Thereby, we make use of the formulation of the scattering of waves off such sheets provided earlier. We consider all limiting cases, providing a link to earlier results. Also, we discuss the relation to the pairwise summation method.

  6. Fractal lattice of gelatin nanoglobules

    NASA Astrophysics Data System (ADS)

    Novikov, D. V.; Krasovskii, A. N.

    2012-11-01

    The globular structure of polymer coatings on a glass, which were obtained from micellar solutions of gelatin in the isooctane-water-sodium (bis-2-ethylhexyl) sulfosuccinate system, has been studied using electron microscopy. It has been shown that an increase in the average globule size is accompanied by the formation of a fractal lattice of nanoglobules and a periodic physical network of macromolecules in the coating. The stability of such system of the "liquid-in-a-solid" type is limited by the destruction of globules and the formation of a homogeneous network structure of the coating.

  7. Hadron structure from lattice QCD

    SciTech Connect

    Green, Jeremy

    2016-01-22

    Recent progress in lattice QCD calculations of nucleon structure will be presented. Calculations of nucleon matrix elements and form factors have long been difficult to reconcile with experiment, but with advances in both methodology and computing resources, this situation is improving. Some calculations have produced agreement with experiment for key observables such as the axial charge and electromagnetic form factors, and the improved understanding of systematic errors will help to increase confidence in predictions of unmeasured quantities. The long-omitted disconnected contributions are now seeing considerable attention and some recent calculations of them will be discussed.

  8. GLAD: A Generic LAttice Debugger

    SciTech Connect

    Lee, M.J.

    1991-11-01

    Today, numerous simulation and analysis codes exist for the design, commission, and operation of accelerator beam lines. There is a need to develop a common user interface and database link to run these codes interactively. This paper will describe a proposed system, GLAD (Generic LAttice Debugger), to fulfill this need. Specifically, GLAD can be used to find errors in beam lines during commissioning, control beam parameters during operation, and design beam line optics and error correction systems for the next generation of linear accelerators and storage rings.

  9. Colliding-beam-accelerator lattice

    SciTech Connect

    Claus, J.; Cornacchia, M.; Courant, E.D.; Parzen, G.

    1983-01-01

    We describe the lattice of the Colliding Beam Accelerator, a 400 x 400 GeV pp facility proposed for construction at Brookhaven National Laboratory. The structure adopted is very versatile, in part in consequence of its desirable behavior as function of momentum deviation and as function of the betatron tunes. Each of the six insertions can be arranged to meet specific requirements at the crossing points as illustrated by a discussion of the tuneable low-beta insertions. The luminosity in these low-beta insertions (2 x 10/sup 33/ cm/sup -2/ sec/sup -1/) would be an order of magnitude larger than the standard insertions.

  10. Percolation in finite matching lattices

    NASA Astrophysics Data System (ADS)

    Mertens, Stephan; Ziff, Robert M.

    2016-12-01

    We derive an exact, simple relation between the average number of clusters and the wrapping probabilities for two-dimensional percolation. The relation holds for periodic lattices of any size. It generalizes a classical result of Sykes and Essam, and it can be used to find exact or very accurate approximations of the critical density. The criterion that follows is related to the criterion used by Scullard and Jacobsen to find precise approximate thresholds, and our work provides a different perspective on their approach.

  11. Lattice models of biological growth

    SciTech Connect

    Young, D.A.; Corey, E.M. )

    1990-06-15

    We show that very simple iterative rules for the growth of cells on a two-dimensional lattice can simulate biological-growth phenomena realistically. We discuss random cellular automata models for the growth of fern gametophytes, branching fungi, and leaves, and for shape transformations useful in the study of biological variation and evolution. Although there are interesting analogies between biological and physical growth processes, we stress the uniqueness of biological automata behavior. The computer growth algorithms that successfully mimic observed growth behavior may be helpful in determining the underlying biochemical mechanisms of growth regulation.

  12. Working Group Report: Lattice Field Theory

    SciTech Connect

    Blum, T.; et al.,

    2013-10-22

    This is the report of the Computing Frontier working group on Lattice Field Theory prepared for the proceedings of the 2013 Community Summer Study ("Snowmass"). We present the future computing needs and plans of the U.S. lattice gauge theory community and argue that continued support of the U.S. (and worldwide) lattice-QCD effort is essential to fully capitalize on the enormous investment in the high-energy physics experimental program. We first summarize the dramatic progress of numerical lattice-QCD simulations in the past decade, with some emphasis on calculations carried out under the auspices of the U.S. Lattice-QCD Collaboration, and describe a broad program of lattice-QCD calculations that will be relevant for future experiments at the intensity and energy frontiers. We then present details of the computational hardware and software resources needed to undertake these calculations.

  13. Localization of Waves in Merged Lattices

    PubMed Central

    Alagappan, G.; Png, C. E.

    2016-01-01

    This article describes a new two–dimensional physical topology–merged lattice, that allows dense number of wave localization states. Merged lattices are obtained as a result of merging two lattices of scatters of the same space group, but with slightly different spatial resonances. Such merging creates two–dimensional scattering “beats” which are perfectly periodic on the longer spatial scale. On the shorter spatial scale, the systematic breakage of the translational symmetry leads to strong wave scattering, and this causes the occurrences of wave localization states. Merged Lattices promises variety of localization states including tightly confined, and ring type annular modes. The longer scale perfect periodicity of the merged lattice, enables complete prediction and full control over the density of the localization states and its’ quality factors. In addition, the longer scale periodicity, also allows design of integrated slow wave components. Merged lattices, thus, can be engineered easily to create technologically beneficial applications. PMID:27535096

  14. Localization of Waves in Merged Lattices.

    PubMed

    Alagappan, G; Png, C E

    2016-08-18

    This article describes a new two-dimensional physical topology-merged lattice, that allows dense number of wave localization states. Merged lattices are obtained as a result of merging two lattices of scatters of the same space group, but with slightly different spatial resonances. Such merging creates two-dimensional scattering "beats" which are perfectly periodic on the longer spatial scale. On the shorter spatial scale, the systematic breakage of the translational symmetry leads to strong wave scattering, and this causes the occurrences of wave localization states. Merged Lattices promises variety of localization states including tightly confined, and ring type annular modes. The longer scale perfect periodicity of the merged lattice, enables complete prediction and full control over the density of the localization states and its' quality factors. In addition, the longer scale periodicity, also allows design of integrated slow wave components. Merged lattices, thus, can be engineered easily to create technologically beneficial applications.

  15. Localization of Waves in Merged Lattices

    NASA Astrophysics Data System (ADS)

    Alagappan, G.; Png, C. E.

    2016-08-01

    This article describes a new two-dimensional physical topology-merged lattice, that allows dense number of wave localization states. Merged lattices are obtained as a result of merging two lattices of scatters of the same space group, but with slightly different spatial resonances. Such merging creates two-dimensional scattering “beats” which are perfectly periodic on the longer spatial scale. On the shorter spatial scale, the systematic breakage of the translational symmetry leads to strong wave scattering, and this causes the occurrences of wave localization states. Merged Lattices promises variety of localization states including tightly confined, and ring type annular modes. The longer scale perfect periodicity of the merged lattice, enables complete prediction and full control over the density of the localization states and its’ quality factors. In addition, the longer scale periodicity, also allows design of integrated slow wave components. Merged lattices, thus, can be engineered easily to create technologically beneficial applications.

  16. Study a compound orthorhombic lattice pattern in dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Dong, Lifang; Gao, Xing; Liu, Weibo; Wei, Lingyan; Pan, Yuyang

    2016-12-01

    The compound orthorhombic lattice pattern which is composed of the bright spot and the dim spot is observed for the first time in a dielectric barrier discharge system. It is found that the dim spot is located at the gravity center of the surrounding three bright spots. The discharge bifurcates from a square lattice, hexagon pattern to compound orthorhombic lattice pattern and finally changes to an irregular pattern. The phase diagram of the pattern types as a function of the applied voltage and the argon concentration is given. The spatio-temporal dynamics of the pattern is studied by the time correlation measurement and the high speed video camera images. Results show that the dim spot is formed by both volume discharge and surface discharge induced by the bright spot. The differences of plasma parameters between the bright spots and the dim spots obtained by optical emission spectroscopy verify that the dim spot is formed by both volume discharge and surface discharge. To better understand the mechanism of firing of the dim spots for the same conditions as in the first phase diagram, the phase diagram of the mechanism of firing of the dim spots as a function of the gas pressure and the argon concentration is given. The simulation of the electric fields of wall charges accumulated by bright spots further verifies that the bright spot has an effect on the formation of dim spot.

  17. Experimental generation of optical coherence lattices

    SciTech Connect

    Chen, Yahong; Cai, Yangjian E-mail: yangjiancai@suda.edu.cn; Ponomarenko, Sergey A. E-mail: yangjiancai@suda.edu.cn

    2016-08-08

    We report experimental generation and measurement of recently introduced optical coherence lattices. The presented optical coherence lattice realization technique hinges on a superposition of mutually uncorrelated partially coherent Schell-model beams with tailored coherence properties. We show theoretically that information can be encoded into and, in principle, recovered from the lattice degree of coherence. Our results can find applications to image transmission and optical encryption.

  18. Observing dynamical SUSY breaking with lattice simulation

    SciTech Connect

    Kanamori, Issaku

    2008-11-23

    On the basis of the recently developed lattice formulation of supersymmetric theories which keeps a part of the supersymmetry, we propose a method of observing dynamical SUSY breaking with lattice simulation. We use Hamiltonian as an order parameter and measure the ground state energy as a zero temperature limit of the finite temperature simulation. Our method provides a way of obtaining a physical result from the lattice simulation for supersymmetric theories.

  19. Bose-Einstein condensates in rotating lattices.

    PubMed

    Bhat, Rajiv; Holland, M J; Carr, L D

    2006-02-17

    Strongly interacting bosons in a two-dimensional rotating square lattice are investigated via a modified Bose-Hubbard Hamiltonian. Such a system corresponds to a rotating lattice potential imprinted on a trapped Bose-Einstein condensate. Second-order quantum phase transitions between states of different symmetries are observed at discrete rotation rates. For the square lattice we study, there are four possible ground-state symmetries.

  20. Trapping Rydberg Atoms in an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Anderson, Sarah E.

    2012-06-01

    Optical lattice traps for Rydberg atoms are of interest in advanced science and in practical applications. After a brief discussion of these areas of interest, I will review some basics of optical Rydberg-atom trapping. The trapping potential experienced by a Rydberg atom in an optical lattice is given by the spatial average of the free-electron ponderomotive energy weighted by the Rydberg electron's probability distribution. I will then present experimental results on the trapping of ^85Rb Rydberg atoms in a one-dimensional ponderomotive optical lattice (wavelength 1064 nm). The principal methods employed to study the lattice performance are microwave spectroscopy, which is used to measure the lattice's trapping efficiency, and photo-ionization, which is used to measure the dwell time of the atoms in the lattice. I have achieved a 90% trapping efficiency for ^85Rb 50S atoms by inverting the lattice immediately after laser excitation of ground-state atoms into Rydberg states. I have characterized the dwell time of the atoms in the lattice using photo-ionization of 50D5/2 atoms. In continued work, I have explored the dependence of the Rydberg-atom trapping potential on the angular portion of the atomic wavefunction. Distinct angular states exhibit different trapping behavior in the optical lattice, depending on how their wavefunctions are oriented relative to the lattice planes. Specifically, I have measured the lattice potential depth of sublevels of ^85Rb nD atoms (50<=n<=65) in a one-dimensional optical lattice with a transverse DC electric field. The trapping behavior varies substantially for the various angular sublevels, in agreement with theory. The talk will conclude with an outlook into planned experiments.

  1. Computational study of lattice models

    NASA Astrophysics Data System (ADS)

    Zujev, Aleksander

    This dissertation is composed of the descriptions of a few projects undertook to complete my doctorate at the University of California, Davis. Different as they are, the common feature of them is that they all deal with simulations of lattice models, and physics which results from interparticle interactions. As an example, both the Feynman-Kikuchi model (Chapter 3) and Bose-Fermi mixture (Chapter 4) deal with the conditions under which superfluid transitions occur. The dissertation is divided into two parts. Part I (Chapters 1-2) is theoretical. It describes the systems we study - superfluidity and particularly superfluid helium, and optical lattices. The numerical methods of working with them are described. The use of Monte Carlo methods is another unifying theme of the different projects in this thesis. Part II (Chapters 3-6) deals with applications. It consists of 4 chapters describing different projects. Two of them, Feynman-Kikuchi model, and Bose-Fermi mixture are finished and published. The work done on t - J model, described in Chapter 5, is more preliminary, and the project is far from complete. A preliminary report on it was given on 2009 APS March meeting. The Isentropic project, described in the last chapter, is finished. A report on it was given on 2010 APS March meeting, and a paper is in preparation. The quantum simulation program used for Bose-Fermi mixture project was written by our collaborators Valery Rousseau and Peter Denteneer. I had written my own code for the other projects.

  2. The Fermilab lattice supercomputer project

    SciTech Connect

    Fischler, M.; Atac, R.; Cook, A.; Deppe, J.; Gaines, I.; Husby, D.; Nash, T.; Pham, T.; Zmuda, T.; Hockney, G.

    1989-02-01

    The ACPMAPS system is a highly cost effective, local memory MIMD computer targeted at algorithm development and production running for gauge theory on the lattice. The machine consists of a compound hypercube of crates, each of which is a full crossbar switch containing several processors. The processing nodes are single board array processors based on the Weitek XL chip set, each with a peak power of 20 MFLOPS and supported by 8 MBytes of data memory. The system currently being assembled has a peak power of 5 GFLOPS, delivering performance at approximately $250/MFLOP. The system is programmable in C and Fortran. An underpinning of software routines (CANOPY) provides an easy and natural way of coding lattice problems, such that the details of parallelism, and communication and system architecture are transparent to the user. CANOPY can easily be ported to any single CPU or MIMD system which supports C, and allows the coding of typical applications with very little effort. 3 refs., 1 fig.

  3. QCD thermodynamics on a lattice

    NASA Astrophysics Data System (ADS)

    Levkova, Ludmila A.

    Numerical simulations of full QCD on anisotropic lattices provide a convenient way to study QCD thermodynamics with fixed physics scales and reduced lattice spacing errors. We report results from calculations with two flavors of dynamical staggered fermions, where all bare parameters and the renormalized anisotropy are kept constant and the temperature is changed in small steps by varying only the number of time slices. Including results from zero-temperature scale setting simulations, which determine the Karsch coefficients, allows for the calculation of the Equation of State at finite temperatures. We also report on studies of the chiral properties of dynamical domain-wall fermions combined with the DBW2 gauge action for different gauge couplings and fermion masses. For quenched theories, the DBW2 action gives a residual chiral symmetry breaking much smaller than what was found with more traditional choices for the gauge action. Our goal is to investigate the possibilities which this and further improvements provide for the study of QCD thermodynamics and other simulations at stronger couplings.

  4. Collapsing lattice animals and lattice trees in two dimensions

    NASA Astrophysics Data System (ADS)

    Hsu, Hsiao-Ping; Grassberger, Peter

    2005-06-01

    We present high statistics simulations of weighted lattice bond animals and lattice trees on the square lattice, with fugacities for each non-bonded contact and for each bond between two neighbouring monomers. The simulations are performed using a newly developed sequential sampling method with resampling, very similar to the pruned-enriched Rosenbluth method (PERM) used for linear chain polymers. We determine with high precision the line of second-order transitions from an extended to a collapsed phase in the resulting two-dimensional phase diagram. This line includes critical bond percolation as a multicritical point, and we verify that this point divides the line into different universality classes. One of them corresponds to the collapse driven by contacts and includes the collapse of (weakly embeddable) trees. There is some evidence that the other is subdivided again into two parts with different universality classes. One of these (at the far side from collapsing trees) is bond driven and is represented by the Derrida-Herrmann model of animals having bonds only (no contacts). Between the critical percolation point and this bond-driven collapse seems to be an intermediate regime, whose other end point is a multicritical point P* where a transition line between two collapsed phases (one bond driven and the other contact driven) sparks off. This point P* seems to be attractive (in the renormalization group sense) from the side of the intermediate regime, so there are four universality classes on the transition line (collapsing trees, critical percolation, intermediate regime, and Derrida-Herrmann). We obtain very precise estimates for all critical exponents for collapsing trees. It is already harder to estimate the critical exponents for the intermediate regime. Finally, it is very difficult to obtain with our method good estimates of the critical parameters of the Derrida-Herrmann universality class. As regards the bond-driven to contact-driven transition in the

  5. Commissioning Simulations for the APS Upgrade Lattice

    SciTech Connect

    Sajaev, V.; Borland, M.

    2015-01-01

    A hybrid seven-bend-achromat lattice that features very strong focusing elements and a relatively small vacuum chamber has been proposed for the APS upgrade. Achieving design lattice parameters during commissioning will need to be accomplished quickly in order to minimize dark time for APS users. The paper will describe start-to-end simulation of the machine commissioning beginning from first-turn trajectory correction, progressing to orbit and lattice correction, and culminating in evaluation of the nonlinear performance of the corrected lattice

  6. Dark periodic lattices in nonlinear liquid media

    NASA Astrophysics Data System (ADS)

    Alvarado-Méndez, Edgar; Trejo-Durán, Mónica; Cano-Lara, Miroslava; Huerta-Mascotte, Eduardo; Castaňo, Víctor M.

    2007-11-01

    Experimental evidence of the formation of one- and two-dimensional dark periodic lattices in a negative Kerr-type nonlinear liquid media is presented. Bright periodic lattices propagate throughout two nonlinear liquids [alcohol with rhodamine (R6G), and acetone with R6G] as the negative nonlinear refractive index forms a dark periodic lattice. Our experiments demonstrate that the nonlinearity increases with the optical power and that a proper selection of the period leads to self-phase modulation of the lattice.

  7. Elastic lattice in an incommensurate background

    SciTech Connect

    Dickman, R.; Chudnovsky, E.M. )

    1995-01-01

    We study a harmonic triangular lattice, which relaxes in the presence of an incommensurate short-wavelength potential. Monte Carlo simulations reveal that the elastic lattice exhibits only short-ranged translational correlations, despite the absence of defects in either lattice. Extended orientational order, however, persists in the presence of the background. Translational correlation lengths exhibit approximate power-law dependence upon cooling rate and background strength. Our results may be relevant to Wigner crystals, atomic monolayers on crystals surfaces, and flux-line and magnetic bubble lattices.

  8. Lattices of processes in graphs with inputs

    SciTech Connect

    Shakhbazyan, K.V.

    1995-09-01

    This article is a continuation of others work, presenting a detailed analysis of finite lattices of processes in graphs with input nodes. Lattices of processes in such graphs are studied by representing the lattices in the form of an algebra of pairs. We define the algebra of pairs somewhat generalizing the definition. Let K and D be bounded distributive lattices. A sublattice {delta} {contained_in} K x D is called an algebra of pairs if for all K {element_of} K we have (K, 1{sub D}) {element_of} {delta} and for all d {element_of} D we have (O{sub K}).

  9. One-dimensional lattices topologically equivalent to two-dimensional lattices within the context of the lattice gas model, III. The hexagonal lattice

    NASA Astrophysics Data System (ADS)

    Costanza, E. F.; Costanza, G.

    2017-02-01

    Continuum partial differential equations are obtained from a set of discrete stochastic evolution equations of both non-Markovian and Markovian processes and applied to the diffusion within the context of the lattice gas model. A procedure allowing to construct one-dimensional lattices that are topologically equivalent to two-dimensional lattices is described in detail in the case of a hexagonal lattice which has the particular feature that need four types of dynamical variables. This example shows additional features to the general procedure and some extensions are also suggested in order to provide a wider insight in the present approach.

  10. One-dimensional lattices topologically equivalent to two-dimensional lattices within the context of the lattice gas model. II The triangular lattice

    NASA Astrophysics Data System (ADS)

    Costanza, E. F.; Costanza, G.

    2016-12-01

    Continuum partial differential equations are obtained from a set of discrete stochastic evolution equations of both non-Markovian and Markovian processes and applied to the diffusion within the context of the lattice gas model. A procedure allowing to construct one-dimensional lattices that are topologically equivalent to two-dimensional lattices is described in detail in the case of a triangular lattice. This example shows the general features that possess the procedure and extensions are also suggested in order to provide a wider insight in the present approach.

  11. Buckling of imperfect periodic lattice structures

    NASA Technical Reports Server (NTRS)

    Anderson, M. S.

    1983-01-01

    A simplified buckling analysis is presented for a family of periodic lattice structures such as those proposed for large space structures. A transcendental 6 x 6 matrix of eigenvalues is shown to be sufficient for modeling buckling behavior because member stiffnesses are based on an exact solution of the beam-column equation. Exact stiffnesses are derived for a curved member, thus allowing modeling of imperfect lattice structures. Comparisons of predictions of the lattice model with those available from shell and beam theory underscore the inaccuracies introduced by treating the lattice structure as a continuum. Sample calculations are provided for an isogrid cylinder and a three element double-laced truss.

  12. Polarization response of RHIC electron lens lattices

    DOE PAGES

    Ranjbar, V. H.; Méot, F.; Bai, M.; ...

    2016-10-10

    Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. Particularly, we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and threshold strengths of the spin resonances. Furthermore, these results are benchmarked and compared to two dimensional direct tracking results for the RHIC e-lens lattice and the standard lattice. We then consider the effect of longitudinal motion via chromatic scans using direct six dimensional lattice tracking.

  13. Subwavelength Lattice Optics by Evolutionary Design

    PubMed Central

    2015-01-01

    This paper describes a new class of structured optical materials—lattice opto-materials—that can manipulate the flow of visible light into a wide range of three-dimensional profiles using evolutionary design principles. Lattice opto-materials are based on the discretization of a surface into a two-dimensional (2D) subwavelength lattice whose individual lattice sites can be controlled to achieve a programmed optical response. To access a desired optical property, we designed a lattice evolutionary algorithm that includes and optimizes contributions from every element in the lattice. Lattice opto-materials can exhibit simple properties, such as on- and off-axis focusing, and can also concentrate light into multiple, discrete spots. We expanded the unit cell shapes of the lattice to achieve distinct, polarization-dependent optical responses from the same 2D patterned substrate. Finally, these lattice opto-materials can also be combined into architectures that resemble a new type of compound flat lens. PMID:25380062

  14. Potts and percolation models on bowtie lattices.

    PubMed

    Ding, Chengxiang; Wang, Yancheng; Li, Yang

    2012-08-01

    We give the exact critical frontier of the Potts model on bowtie lattices. For the case of q = 1, the critical frontier yields the thresholds of bond percolation on these lattices, which are exactly consistent with the results given by Ziff et al. [J. Phys. A 39, 15083 (2006)]. For the q = 2 Potts model on a bowtie A lattice, the critical point is in agreement with that of the Ising model on this lattice, which has been exactly solved. Furthermore, we do extensive Monte Carlo simulations of the Potts model on a bowtie A lattice with noninteger q. Our numerical results, which are accurate up to seven significant digits, are consistent with the theoretical predictions. We also simulate the site percolation on a bowtie A lattice, and the threshold is s(c) = 0.5479148(7). In the simulations of bond percolation and site percolation, we find that the shape-dependent properties of the percolation model on a bowtie A lattice are somewhat different from those of an isotropic lattice, which may be caused by the anisotropy of the lattice.

  15. Polarization response of RHIC electron lens lattices

    NASA Astrophysics Data System (ADS)

    Ranjbar, V. H.; Méot, F.; Bai, M.; Abell, D. T.; Meiser, D.

    2016-10-01

    Depolarization response for a system of two orthogonal snakes at irrational tunes is studied in depth using lattice independent spin integration. In particular we consider the effect of overlapping spin resonances in this system, to understand the impact of phase, tune, relative location and threshold strengths of the spin resonances. These results are benchmarked and compared to two dimensional direct tracking results for the RHIC e-lens lattice and the standard lattice. Finally we consider the effect of longitudinal motion via chromatic scans using direct six dimensional lattice tracking.

  16. Minio Vallis Channel

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    This VIS image is of the southern reach of Minio Vallis, a small fluvial channel located near the larger Mangala Vallis. Both channels are in the Tharsis region, in the area west of Arsia Mons and southeast of Medusae Fossae.

    Image information: VIS instrument. Latitude -8.2, Longitude 208.1 East (151.9 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  17. Channel Wall Landslides

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The multiple landslides in this VIS image occur along a steep channel wall. Note the large impact crater in the context image. The formation of the crater may have initially weakened that area of the surface prior to channel formation.

    Image information: VIS instrument. Latitude -2.7, Longitude 324.8 East (35.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  18. Channel Wall Landslides

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The multiple landslides in this VIS image occur along a steep channel wall. Note the large impact crater in the context image. The formation of the crater may have initially weakened that area of the surface prior to channel formation.

    Image information: VIS instrument. Latitude -2.7, Longitude 324.8 East (35.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  19. Channel to Nowhere

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 22 May 2003

    A channel-like feature roughly halfway between the Isidis Basin and Elysium Mons shows no connection to either a source region or terminal basin. It may be that this feature is not a channel at all and has instead arisen from the erosion of a once continuous layer of material into remnants that mimic a channel.

    Image information: VIS instrument. Latitude 20.9, Longitude 105 East (255) meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  20. Channels and Erosion

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 20 June 2003

    The dissected and eroded channel observed in this THEMIS image taken of plains materials southwest of the volcano Elysium Mons shows typical erosional islands and depositional features. The interesting thing about this channel is that it appears to start out of nowhere. The MOLA context image shows that the channel originates from a fissure within the ground, whose origin is likely volcanic, but may also be related to volatile processes.

    Image information: VIS instrument. Latitude 19.5, Longitude 126.8 East (233.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  1. Channels and Erosion

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 20 June 2003

    The dissected and eroded channel observed in this THEMIS image taken of plains materials southwest of the volcano Elysium Mons shows typical erosional islands and depositional features. The interesting thing about this channel is that it appears to start out of nowhere. The MOLA context image shows that the channel originates from a fissure within the ground, whose origin is likely volcanic, but may also be related to volatile processes.

    Image information: VIS instrument. Latitude 19.5, Longitude 126.8 East (233.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. Effect of impurities on the vortex lattice in Bose-Einstein condensates on optical lattice

    NASA Astrophysics Data System (ADS)

    Mithun, T.; Porsezian, K.; Dey, Bishwajyoti

    2015-06-01

    We numerically solve the Gross-Pitaeveskii equation to study the Bose-Einstein condensate in the rotating harmonical tarp and co-rotating optical lattice. The effect of a pinning site or impurity shows that it is able to move the vortex lattice center to either left or right depending on the position of the impurity. Also, it is observed that the impurity at the random positions can destroy the vortex lattice and the resulting disordered lattice has more energy.

  3. Meson Resonances from Lattice QCD

    SciTech Connect

    Edwards, Robert G.

    2016-06-01

    There has been recent, significant, advances in the determination of the meson spectrum of QCD. Current efforts have focused on the development and application of finite-volume formalisms that allow for the determination of scattering amplitudes as well as resonance behavior in coupled channel systems. I will review some of these recent developments, and demonstrate the viability of the method in meson systems.

  4. Meson resonances on the lattice

    SciTech Connect

    Edwards, Robert G.

    2016-06-01

    There has been recent, significant, advances in the determination of the meson spectrum of QCD. Current efforts have focused on the development and application of finite-volume formalisms that allow for the determination of scattering amplitudes as well as resonance behavior in coupled channel systems. I will review some of these recent developments, and demonstrate the viability of the method in meson systems

  5. Eukaryotic mechanosensitive channels.

    PubMed

    Arnadóttir, Jóhanna; Chalfie, Martin

    2010-01-01

    Mechanosensitive ion channels are gated directly by physical stimuli and transduce these stimuli into electrical signals. Several criteria must apply for a channel to be considered mechanically gated. Mechanosensitive channels from bacterial systems have met these criteria, but few eukaryotic channels have been confirmed by the same standards. Recent work has suggested or confirmed that diverse types of channels, including TRP channels, K(2P) channels, MscS-like proteins, and DEG/ENaC channels, are mechanically gated. Several studies point to the importance of the plasma membrane for channel gating, but intracellular and/or extracellular structures may also be required.

  6. Bimaterial lattices as thermal adapters and actuators

    NASA Astrophysics Data System (ADS)

    Toropova, Marina M.; Steeves, Craig A.

    2016-11-01

    The goal of this paper is to demonstrate how anisotropic biomaterial lattices can be used in thermal actuation. Compared to other lattices with tailored thermal expansion, the anisotropy of these bimaterial lattices makes them uniquely suitable for use as thermal actuators. Each individual cell, and hence lattices consisting of such cells, can be designed with widely different predetermined coefficients of thermal expansion (CTE) in different directions, enabling complex shape changes appropriate for actuation with either passive or active control. The lattices are composed of planar non-identical cells that each consist of a skewed hexagon surrounding an irregular triangle. The cells and all members of any cell are connected to each other by pins so that they have no rotational constraints and are able to expand or contract freely. In this case, the skew angles of the hexagon and the ratio of the CTEs of the two component materials determine the overall performance of the lattice. At its boundaries, the lattice is connected to substrates by pins and configured such that the CTE between two neighboring lattice vertices coincides with the CTE of the adjacent substrate. Provided the boundary behavior of the lattice is matched to the thermal properties of the substrates, temperature changes in the structure produce thermal strains without producing any corresponding stresses. Such lattices can be used in three different ways: as adaptive elements for stress-free connection of components with different CTEs; for fine tuning of structures; and as thermally driven actuators. In this paper, we demonstrate some concepts for lattice configurations that produce thermally-driven displacements that enable several actuators: a switch, a valve and tweezers.

  7. Cold atoms in a rotating optical lattice

    NASA Astrophysics Data System (ADS)

    Foot, Christopher J.

    2009-05-01

    We have demonstrated a novel experimental arrangement which can rotate a two-dimensional optical lattice at frequencies up to several kilohertz. Our arrangement also allows the periodicity of the optical lattice to be varied dynamically, producing a 2D ``accordion lattice'' [1]. The angles of the laser beams are controlled by acousto-optic deflectors and this allows smooth changes with little heating of the trapped cold (rubidium) atoms. We have loaded a BEC into lattices with periodicities ranging from 1.8μm to 18μm, observing the collapse and revival of the diffraction orders of the condensate over a large range of lattice parameters as recently reported by a group in NIST [2]. We have also imaged atoms in situ in a 2D lattice over a range of lattice periodicities. Ultracold atoms in a rotating lattice can be used for the direct quantum simulation of strongly correlated systems under large effective magnetic fields, i.e. the Hamiltonian of the atoms in the rotating frame resembles that of a charged particle in a strong magnetic field. In the future, we plan to use this to investigate a range of phenomena such as the analogue of the fractional quantum Hall effect. [4pt] [1] R. A. Williams, J. D. Pillet, S. Al-Assam, B. Fletcher, M. Shotter, and C. J. Foot, ``Dynamic optical lattices: two-dimensional rotating and accordion lattices for ultracold atoms,'' Opt. Express 16, 16977-16983 (2008) [0pt] [2] J. H. Huckans, I. B. Spielman, B. Laburthe Tolra, W. D. Phillips, and J. V. Porto, Quantum and Classical Dynamics of a BEC in a Large-Period Optical Lattice, arXiv:0901.1386v1

  8. Photogenerated excitons in plain core CdSe nanocrystals with unity radiative decay in single channel: the effects of surface and ligands.

    PubMed

    Gao, Yuan; Peng, Xiaogang

    2015-04-01

    A systematic and reproducible method was developed to study the decay dynamics of an exciton, a photogenerated electron-hole pair, in semiconductor nanocrystals in solution. Results revealed that the excitons in plain core CdSe nanocrystals in either zinc-blende or wurtzite or mixed lattice structures could be reproducibly prepared to decay radiatively in unity quantum yield and in single channel. The single-channel lifetime was found to increase monotonically by increasing size of the CdSe nanocrystals, with zinc-blende ones increasing in a relatively slow pace. Surface inorganic stoichiometry was found to be a sensitive parameter to affect the exciton decay dynamics for all crystal structures with different sizes. Excess Se (Cd) sites on the surface were found to induce short (long) lifetime channels for the excitons. Both types of traps reduced the quantum yield of the radiative decay of the excitons, and the hole traps associated with Se sites were nearly not emissive. With optimal surface inorganic stoichiometry, primary amines were identified as "ideal" organic ligands for CdSe core nanocrystals to achieve unity radiative decay of excitons in single channel in comparison to other types of neutral ligands commonly applied in the field.

  9. Entropy of Open Lattice Systems

    NASA Astrophysics Data System (ADS)

    Derrida, B.; Lebowitz, J. L.; Speer, E. R.

    2007-03-01

    We investigate the behavior of the Gibbs-Shannon entropy of the stationary nonequilibrium measure describing a one-dimensional lattice gas, of L sites, with symmetric exclusion dynamics and in contact with particle reservoirs at different densities. In the hydrodynamic scaling limit, L → ∞, the leading order ( O( L)) behavior of this entropy has been shown by Bahadoran to be that of a product measure corresponding to strict local equilibrium; we compute the first correction, which is O(1). The computation uses a formal expansion of the entropy in terms of truncated correlation functions; for this system the k th such correlation is shown to be O( L - k+1). This entropy correction depends only on the scaled truncated pair correlation, which describes the covariance of the density field. It coincides, in the large L limit, with the corresponding correction obtained from a Gaussian measure with the same covariance.

  10. On lattice chiral gauge theories

    NASA Technical Reports Server (NTRS)

    Maiani, L.; Rossi, G. C.; Testa, M.

    1991-01-01

    The Smit-Swift-Aoki formulation of a lattice chiral gauge theory is presented. In this formulation the Wilson and other non invariant terms in the action are made gauge invariant by the coupling with a nonlinear auxilary scalar field, omega. It is shown that omega decouples from the physical states only if appropriate parameters are tuned so as to satisfy a set of BRST identities. In addition, explicit ghost fields are necessary to ensure decoupling. These theories can give rise to the correct continuum limit. Similar considerations apply to schemes with mirror fermions. Simpler cases with a global chiral symmetry are discussed and it is shown that the theory becomes free at decoupling. Recent numerical simulations agree with those considerations.

  11. Lattice mechanics of origami tessellations

    NASA Astrophysics Data System (ADS)

    Evans, Arthur A.; Silverberg, Jesse L.; Santangelo, Christian D.

    2015-07-01

    Origami-based design holds promise for developing materials whose mechanical properties are tuned by crease patterns introduced to thin sheets. Although there have been heuristic developments in constructing patterns with desirable qualities, the bridge between origami and physics has yet to be fully developed. To truly consider origami structures as a class of materials, methods akin to solid mechanics need to be developed to understand their long-wavelength behavior. We introduce here a lattice theory for examining the mechanics of origami tessellations in terms of the topology of their crease pattern and the relationship between the folds at each vertex. This formulation provides a general method for associating mechanical properties with periodic folded structures and allows for a concrete connection between more conventional materials and the mechanical metamaterials constructed using origami-based design.

  12. Nuclear forces from lattice QCD

    SciTech Connect

    Ishii, Noriyoshi

    2011-05-06

    Lattice QCD construction of nuclear forces is reviewed. In this method, the nuclear potentials are constructed by solving the Schroedinger equation, where equal-time Nambu-Bethe-Salpeter (NBS) wave functions are regarded as quantum mechanical wave functions. Since the long distance behavior of equal-time NBS wave functions is controlled by the scattering phase, which is in exactly the same way as scattering wave functions in quantum mechanics, the resulting potentials are faithful to the NN scattering data. The derivative expansion of this potential leads to the central and the tensor potentials at the leading order. Some of numerical results of these two potentials are shown based on the quenched QCD.

  13. Tracking the SSC test lattices

    SciTech Connect

    Leemann, B.T.; Douglas, D.R.; Forest, E.

    1985-10-01

    The dynamic aperture and its determination emerged from the SSC reference design study as the single most important accelerator physics issue pertinent to the SSC. Beside the fundamental need of a finite dynamic aperture for any accelerator, it was considered to be a useful criterion for the magnet selection. An aperture workshop organized in November 1984 at LBL served the purpose to identify the various aspects of the aperture question and to organize the aperture task force accordingly. It was recognized that numerical models had to play an important role and the qualifications of several tracking codes were investigated. None of the existing codes could meet all of the criteria for an ideal tracking code and substantial program development became unavoidable. It was therefore decided to begin tracking SSC test lattices.

  14. Majorana fermions in vortex lattices

    NASA Astrophysics Data System (ADS)

    Biswas, Rudro

    2013-03-01

    We consider Majorana fermions tunneling between vortices, within an array of such vortices in a 2D chiral p-wave superconductor. We calculate that the tunneling amplitude for Majorana fermions in a pair of vortices is proportional to the sine of half the difference between the global order parameter phases at the two vortices. Using this result we study tight-binding models of Majorana fermions in vortices arranged in a triangular or square lattice. In both cases we find that this phase-tunneling relationship leads to the creation of superlattices where the Majorana fermions form macroscopically degenerate `flat' bands at zero energy, in addition to other dispersive bands. This finding suggests that in vortex arrays tunneling processes do not change the energies of a finite fraction of Majorana fermions and hence brighten the prospects of topological quantum computing with a large number of Majorana states.

  15. Lattice mechanics of origami tessellations.

    PubMed

    Evans, Arthur A; Silverberg, Jesse L; Santangelo, Christian D

    2015-07-01

    Origami-based design holds promise for developing materials whose mechanical properties are tuned by crease patterns introduced to thin sheets. Although there have been heuristic developments in constructing patterns with desirable qualities, the bridge between origami and physics has yet to be fully developed. To truly consider origami structures as a class of materials, methods akin to solid mechanics need to be developed to understand their long-wavelength behavior. We introduce here a lattice theory for examining the mechanics of origami tessellations in terms of the topology of their crease pattern and the relationship between the folds at each vertex. This formulation provides a general method for associating mechanical properties with periodic folded structures and allows for a concrete connection between more conventional materials and the mechanical metamaterials constructed using origami-based design.

  16. Reflooding of tight lattice bundles

    SciTech Connect

    Veteau, J.M.; Digonnet, A.; Deruaz, R. . Centre d'Etudes Nucleaires de Grenoble)

    1994-07-01

    Results regarding analytical bottom reflooding experiments in a 37- and a 127-heater rod bundle are presented for two different tight lattices. A comparison between these two geometries and with the standard pressurized water reactor (PWR) array shows a degradation of cooling efficiency when the cross section of the subchannels is decreased. The core heat sinks (guide thimbles and water tubes'') are seen to have a noticeable influence on the overall cooling of the bundle, and it is confirmed that a combined top/bottom injection does not significantly improve cooling efficiency. Calculations with CATHARE 1.3 code adjusted for the standard PWR array are presented (zero heat sinks), but results have to be confirmed over a wider range of parameters.

  17. Realizing Parafermions in Optical Lattices

    NASA Astrophysics Data System (ADS)

    Liu, Fangli; Gorshkov, Alexey

    2016-05-01

    Parafermions, which are the fractional versions of Majorana fermions, possess more exotic braiding statistics than Majorana fermions and are therefore more powerful from the point of view of topological quantum computing. We propose a scheme to realize parafermionic zero modes in optical lattices, without the use of superconductive paring. With the help of laser assisted tunneling and on-site interactions, two layers of ultracold atoms in distinct hyperfine states can be engineered to host +/- 1 / m fractional quantum Hall states. We then introduce a finite-extent potential barrier that pierces both layers - this gives rise to two counter-propagating edge states that sit on top of each other. Finally, laser induced coupling is used to introduce backscattering between the two edge states and to gap them out. We show that the resulting defects give rise to the topological degeneracy associated with parafermions. We also discuss methods for preparation and detection.

  18. FFAG lattice without opposite bends

    NASA Astrophysics Data System (ADS)

    Trbojevic, Dejan; Courant, Ernest D.; Garren, Al

    2000-08-01

    A future "neutrino factory" or Muon Collider requires fast muon acceleration before the storage ring. Several alternatives for fast muon acceleration have previously been considered. One of them is the FFAG (Fixed Field Alternating Gradient) synchrotron. The FFAG concept was developed in 1952 by K. R. Symon (ref. 1). The advantages of this design are the fixed magnetic field, large range of particle energy, simple RF; power supplies are simple, and there is no transition energy. But a drawback is that reverse bending magnets are included in the configuration; this increases the size and cost of the ring. Recently some modified FFAG lattice designs have been described where the amount of opposite bending was significantly reduced (ref. 2, ref. 3).

  19. Results and Frontiers in Lattice Baryon Spectroscopy

    SciTech Connect

    Bulava, John; Morningstar, Colin; Edwards, Robert; Richards, David; Fleming, George; Juge, K. Jimmy; Lichtl, Adam C.; Mathur, Nilmani; Wallace, Stephen J.

    2007-10-26

    The Lattice Hadron Physics Collaboration (LHPC) baryon spectroscopy effort is reviewed. To date the LHPC has performed exploratory Lattice QCD calculations of the low-lying spectrum of Nucleon and Delta baryons. These calculations demonstrate the effectiveness of our method by obtaining the masses of an unprecedented number of excited states with definite quantum numbers. Future work of the project is outlined.

  20. The Chroma Software System for Lattice QCD

    SciTech Connect

    Robert Edwards; Balint Joo

    2004-06-01

    We describe aspects of the Chroma software system for lattice QCD calculations. Chroma is an open source C++ based software system developed using the software infrastructure of the US SciDAC initiative. Chroma interfaces with output from the BAGEL assembly generator for optimized lattice fermion kernels on some architectures. It can be run on workstations, clusters and the QCDOC supercomputer.

  1. Lattice studies of hadrons with heavy flavors

    SciTech Connect

    Christopher Aubin

    2009-07-01

    I will discuss recent developments in lattice studies of hadrons composed of heavy quarks. I will mostly cover topics which are at a state of direct comparison with experiment, but will also discuss new ideas and promising techniques to aid future studies of lattice heavy quark physics.

  2. The mystery of the fifteenth Bravais lattice

    NASA Astrophysics Data System (ADS)

    Nussbaum, Allen

    2000-10-01

    An understanding of the principles of crystal structure is necessary for the study of solids. There are contradictions in the literature dealing with the nature of crystal lattices, and there is also a miscounting of the number of possible lattices. This paper clarifies the situation in a systematic and simple way.

  3. Unorthodox lattice fermion derivatives and their shortcomings

    SciTech Connect

    Bodwin, G.T.; Kovacs, E.V.

    1987-03-10

    We discuss the DWY (Lagrangian), Quinn-Weinstein, and Rebbi proposals for incorporating fermions into lattice gauge theory and analyze them in the context of weak coupling perturbation theory. We find that none of these proposals leads to a completely satisfactory lattice transcription of fully-interacting gauge theory.

  4. Recent advances in lattice Boltzmann methods

    SciTech Connect

    Chen, S.; Doolen, G.D.; He, X.; Nie, X.; Zhang, R.

    1998-12-31

    In this paper, the authors briefly present the basic principles of lattice Boltzmann method and summarize recent advances of the method, including the application of the lattice Boltzmann method for fluid flows in MEMS and simulation of the multiphase mixing and turbulence.

  5. On Some Properties of PBZ*-Lattices

    NASA Astrophysics Data System (ADS)

    Giuntini, Roberto; Ledda, Antonio; Paoli, Francesco

    2017-04-01

    We continue the algebraic investigation of PBZ*-lattices, a notion introduced in Giuntini et al. (Stud. Logica 104, 1145-1177, 2016) in order to obtain insights into the structure of certain algebras of effects of a Hilbert space, lattice-ordered under the spectral ordering.

  6. Disorder solutions of lattice spin models

    NASA Astrophysics Data System (ADS)

    Batchelor, M. T.; van Leeuwen, J. M. J.

    1989-01-01

    It is shown that disorder solutions, which have been obtained by different methods, follow from a simple decimation method. The method is put in general form and new disorder solutions are constructed for the Blume-Emery-Griffiths model on a triangular lattice and for Potts and Ising models on square and fcc lattices.

  7. Selective nanoscale growth of lattice mismatched materials

    DOEpatents

    Lee, Seung-Chang; Brueck, Steven R. J.

    2017-06-20

    Exemplary embodiments provide materials and methods of forming high-quality semiconductor devices using lattice-mismatched materials. In one embodiment, a composite film including one or more substantially-single-particle-thick nanoparticle layers can be deposited over a substrate as a nanoscale selective growth mask for epitaxially growing lattice-mismatched materials over the substrate.

  8. PROGRESS IN LATTICE QCD AT FINITE TEMPERATURE.

    SciTech Connect

    PETRECZKY,P.

    2007-02-11

    I review recent developments in lattice QCD at finite temperature, including the determination of the transition temperature T{sub c}, equation of state and different static screening lengths. The lattice data suggest that at temperatures above 1.5T{sub c} the quark gluon plasma can be considered as gas consisting of quarks and gluons.

  9. Numerical study of localization in antidot lattices

    NASA Astrophysics Data System (ADS)

    Uryu, Seiji; Ando, Tsuneya

    1998-10-01

    Localization effects in antidot lattices in weak magnetic fields are numerically studied with the use of a Thouless-number method. In hexagonal antidot lattices, both conductance and inverse localization length oscillate as a function of a magnetic flux with the same period as an Al'tshuler-Aronov-Spivak oscillation, in qualitative agreement with recent experiments.

  10. Gap solitons in Rabi lattices

    NASA Astrophysics Data System (ADS)

    Chen, Zhaopin; Malomed, Boris A.

    2017-03-01

    We introduce a two-component one-dimensional system, which is based on two nonlinear Schrödinger or Gross-Pitaevskii equations (GPEs) with spatially periodic modulation of linear coupling ("Rabi lattice") and self-repulsive nonlinearity. The system may be realized in a binary Bose-Einstein condensate, whose components are resonantly coupled by a standing optical wave, as well as in terms of the bimodal light propagation in periodically twisted waveguides. The system supports various types of gap solitons (GSs), which are constructed, and their stability is investigated, in the first two finite bandgaps of the underlying spectrum. These include on- and off-site-centered solitons (the GSs of the off-site type are additionally categorized as spatially even and odd ones), which may be symmetric or antisymmetric, with respect to the coupled components. The GSs are chiefly stable in the first finite bandgap and unstable in the second one. In addition to that, there are narrow regions near the right edge of the first bandgap, and in the second one, which feature intricate alternation of stability and instability. Unstable solitons evolve into robust breathers or spatially confined turbulent modes. On-site-centered GSs are also considered in a version of the system that is made asymmetric by the Zeeman effect, or by birefringence of the optical waveguide. A region of alternate stability is found in the latter case too. In the limit of strong asymmetry, GSs are obtained in a semianalytical approximation, which reduces two coupled GPEs to a single one with an effective lattice potential.

  11. Coincident electron channeling and cathodoluminescence studies of threading dislocations in GaN.

    PubMed

    Naresh-Kumar, Gunasekar; Bruckbauer, Jochen; Edwards, Paul R; Kraeusel, Simon; Hourahine, Ben; Martin, Robert W; Kappers, Menno J; Moram, Michelle A; Lovelock, Stephen; Oliver, Rachel A; Humphreys, Colin J; Trager-Cowan, Carol

    2014-02-01

    We combine two scanning electron microscopy techniques to investigate the influence of dislocations on the light emission from nitride semiconductors. Combining electron channeling contrast imaging and cathodoluminescence imaging enables both the structural and luminescence properties of a sample to be investigated without structural damage to the sample. The electron channeling contrast image is very sensitive to distortions of the crystal lattice, resulting in individual threading dislocations appearing as spots with black-white contrast. Dislocations giving rise to nonradiative recombination are observed as black spots in the cathodoluminescence image. Comparison of the images from exactly the same micron-scale region of a sample demonstrates a one-to-one correlation between the presence of single threading dislocations and resolved dark spots in the cathodoluminescence image. In addition, we have also obtained an atomic force microscopy image from the same region of the sample, which confirms that both pure edge dislocations and those with a screw component (i.e., screw and mixed dislocations) act as nonradiative recombination centers for the Si-doped c-plane GaN thin film investigated.

  12. A lattice approach to spinorial quantum gravity

    NASA Technical Reports Server (NTRS)

    Renteln, Paul; Smolin, Lee

    1989-01-01

    A new lattice regularization of quantum general relativity based on Ashtekar's reformulation of Hamiltonian general relativity is presented. In this form, quantum states of the gravitational field are represented within the physical Hilbert space of a Kogut-Susskind lattice gauge theory. The gauge field of the theory is a complexified SU(2) connection which is the gravitational connection for left-handed spinor fields. The physical states of the gravitational field are those which are annihilated by additional constraints which correspond to the four constraints of general relativity. Lattice versions of these constraints are constructed. Those corresponding to the three-dimensional diffeomorphism generators move states associated with Wilson loops around on the lattice. The lattice Hamiltonian constraint has a simple form, and a correspondingly simple interpretation: it is an operator which cuts and joins Wilson loops at points of intersection.

  13. Spin Chains with Dynamical Lattice Supersymmetry

    NASA Astrophysics Data System (ADS)

    Hagendorf, Christian

    2013-02-01

    Spin chains with exact supersymmetry on finite one-dimensional lattices are considered. The supercharges are nilpotent operators on the lattice of dynamical nature: they change the number of sites. A local criterion for the nilpotency on periodic lattices is formulated. Any of its solutions leads to a supersymmetric spin chain. It is shown that a class of special solutions at arbitrary spin gives the lattice equivalents of the {N}=(2,2) superconformal minimal models. The case of spin one is investigated in detail: in particular, it is shown that the Fateev-Zamolodchikov chain and its off-critical extension possess a lattice supersymmetry for all its coupling constants. Its supersymmetry singlets are thoroughly analysed, and a relation between their components and the weighted enumeration of alternating sign matrices is conjectured.

  14. Quantum transport in d-dimensional lattices

    DOE PAGES

    Manzano, Daniel; Chuang, Chern; Cao, Jianshu

    2016-04-28

    We show that both fermionic and bosonic uniform d-dimensional lattices can be reduced to a set of independent one-dimensional chains. This reduction leads to the expression for ballistic energy fluxes in uniform fermionic and bosonic lattices. By the use of the Jordan–Wigner transformation we can extend our analysis to spin lattices, proving the coexistence of both ballistic and non-ballistic subspaces in any dimension and for any system size. Lastly, we then relate the nature of transport to the number of excitations in the homogeneous spin lattice, indicating that a single excitation always propagates ballistically and that the non-ballistic behaviour ofmore » uniform spin lattices is a consequence of the interaction between different excitations.« less

  15. Ising antiferromagnet on the Archimedean lattices

    NASA Astrophysics Data System (ADS)

    Yu, Unjong

    2015-06-01

    Geometric frustration effects were studied systematically with the Ising antiferromagnet on the 11 Archimedean lattices using the Monte Carlo methods. The Wang-Landau algorithm for static properties (specific heat and residual entropy) and the Metropolis algorithm for a freezing order parameter were adopted. The exact residual entropy was also found. Based on the degree of frustration and dynamic properties, ground states of them were determined. The Shastry-Sutherland lattice and the trellis lattice are weakly frustrated and have two- and one-dimensional long-range-ordered ground states, respectively. The bounce, maple-leaf, and star lattices have the spin ice phase. The spin liquid phase appears in the triangular and kagome lattices.

  16. Extended applications of the vortex lattice method

    NASA Technical Reports Server (NTRS)

    Miranda, L. R.

    1976-01-01

    The application of the vortex lattice method to problems not usually dealt with by this technique is considered. It is shown that if the discrete vortex lattice is considered as an approximation to surface-distributed vorticity, then the concept of the generalized principal part of an integral yields a residual term to the vortex-induced velocity that renders the vortex lattice method valid for supersonic flow. Special schemes for simulating non-zero thickness lifting surfaces and fusiform bodies with vortex lattice elements are presented. Thickness effects of wing-like components are simulated by a double vortex lattice layer, and fusiform bodies are represented by a vortex grid arranged on a series of concentric cylindrical surfaces. Numerical considerations peculiar to the application of these techniques are briefly discussed.

  17. Lattice Boltzmann modeling of phonon transport

    NASA Astrophysics Data System (ADS)

    Guo, Yangyu; Wang, Moran

    2016-06-01

    A novel lattice Boltzmann scheme is proposed for phonon transport based on the phonon Boltzmann equation. Through the Chapman-Enskog expansion, the phonon lattice Boltzmann equation under the gray relaxation time approximation recovers the classical Fourier's law in the diffusive limit. The numerical parameters in the lattice Boltzmann model are therefore rigorously correlated to the bulk material properties. The new scheme does not only eliminate the fictitious phonon speed in the diagonal direction of a square lattice system in the previous lattice Boltzmann models, but also displays very robust performances in predicting both temperature and heat flux distributions consistent with analytical solutions for diverse numerical cases, including steady-state and transient, macroscale and microscale, one-dimensional and multi-dimensional phonon heat transport. This method may provide a powerful numerical tool for deep studies of nonlinear and nonlocal heat transports in nanosystems.

  18. Counting lattice animals in high dimensions

    NASA Astrophysics Data System (ADS)

    Luther, Sebastian; Mertens, Stephan

    2011-09-01

    We present an implementation of Redelemeier's algorithm for the enumeration of lattice animals in high-dimensional lattices. The implementation is lean and fast enough to allow us to extend the existing tables of animal counts, perimeter polynomials and series expansion coefficients in d-dimensional hypercubic lattices for 3 <= d <= 10. From the data we compute formulae for perimeter polynomials for lattice animals of size n <= 11 in arbitrary dimension d. When amended by combinatorial arguments, the new data suffice to yield explicit formulae for the number of lattice animals of size n <= 14 and arbitrary d. We also use the enumeration data to compute numerical estimates for growth rates and exponents in high dimensions that agree very well with Monte Carlo simulations and recent predictions from field theory.

  19. Synthetic magnetic fluxes on the honeycomb lattice

    SciTech Connect

    Gorecka, Agnieszka; Gremaud, Benoit; Miniatura, Christian

    2011-08-15

    We devise experimental schemes that are able to mimic uniform and staggered magnetic fluxes acting on ultracold two-electron atoms, such as ytterbium atoms, propagating in a honeycomb lattice. The atoms are first trapped into two independent state-selective triangular lattices and then further exposed to a suitable configuration of resonant Raman laser beams. These beams induce hops between the two triangular lattices and make atoms move in a honeycomb lattice. Atoms traveling around each unit cell of this honeycomb lattice pick up a nonzero phase. In the uniform case, the artificial magnetic flux sustained by each cell can reach about two flux quanta, thereby realizing a cold-atom analog of the Harper model with its notorious Hofstadter's butterfly structure. Different condensed-matter phenomena such as the relativistic integer and fractional quantum Hall effects, as observed in graphene samples, could be targeted with this scheme.

  20. Status of the ATF2 Lattices

    SciTech Connect

    Marin, E.; Tomas, R.; Bambade, P.; Okugi, T.; Tauchi, T.; Terunuma, N.; Urakawa, J.; Seryi, A.; White, G.; Woodley, M.; /SLAC

    2011-12-09

    The current status for the ATF2 Nominal and Ultra-low {beta}* lattices are presented in this paper. New lattice designs have been obtained in order to minimise the impact of the last interpretation of multipole measurements that have been included into the model. However, the new ATF2 Ultra-low design is not able to recover the expected vertical beam size at the IP with the current magnet distribution. Therefore, different quadrupole sorting have been studied. A significant gain is evident for the ATF2 Ultra-low lattice when sorting the magnets according to the skew-sextupolar components. The ATF2 Nominal lattice is also expected to benefit from the new sorting. Tuning results of the new ATF2 Ultra-low lattice under realistic imperfections are also reported.

  1. Synthetic magnetic fluxes on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Górecka, Agnieszka; Grémaud, Benoît; Miniatura, Christian

    2011-08-01

    We devise experimental schemes that are able to mimic uniform and staggered magnetic fluxes acting on ultracold two-electron atoms, such as ytterbium atoms, propagating in a honeycomb lattice. The atoms are first trapped into two independent state-selective triangular lattices and then further exposed to a suitable configuration of resonant Raman laser beams. These beams induce hops between the two triangular lattices and make atoms move in a honeycomb lattice. Atoms traveling around each unit cell of this honeycomb lattice pick up a nonzero phase. In the uniform case, the artificial magnetic flux sustained by each cell can reach about two flux quanta, thereby realizing a cold-atom analog of the Harper model with its notorious Hofstadter’s butterfly structure. Different condensed-matter phenomena such as the relativistic integer and fractional quantum Hall effects, as observed in graphene samples, could be targeted with this scheme.

  2. A lattice approach to spinorial quantum gravity

    NASA Technical Reports Server (NTRS)

    Renteln, Paul; Smolin, Lee

    1989-01-01

    A new lattice regularization of quantum general relativity based on Ashtekar's reformulation of Hamiltonian general relativity is presented. In this form, quantum states of the gravitational field are represented within the physical Hilbert space of a Kogut-Susskind lattice gauge theory. The gauge field of the theory is a complexified SU(2) connection which is the gravitational connection for left-handed spinor fields. The physical states of the gravitational field are those which are annihilated by additional constraints which correspond to the four constraints of general relativity. Lattice versions of these constraints are constructed. Those corresponding to the three-dimensional diffeomorphism generators move states associated with Wilson loops around on the lattice. The lattice Hamiltonian constraint has a simple form, and a correspondingly simple interpretation: it is an operator which cuts and joins Wilson loops at points of intersection.

  3. Chaotic phenomena of charged particles in crystal lattices.

    PubMed

    Desalvo, Agostino; Giannerini, Simone; Rosa, Rodolfo

    2006-06-01

    In this article, we have applied the methods of chaos theory to channeling phenomena of positive charged particles in crystal lattices. In particular, we studied the transition between two ordered types of motion; i.e., motion parallel to a crystal axis (axial channeling) and to a crystal plane (planar channeling), respectively. The transition between these two regimes turns out to occur through an angular range in which the particle motion is highly disordered and the region of phase space spanned by the particle is much larger than the one swept in the two ordered motions. We have evaluated the maximum Lyapunov exponent with the method put forward by Rosenstein et al. [Physica D 65, 117 (1993)] and by Kantz [Phys. Lett. A 185, 77 (1994)]. Moreover, we estimated the correlation dimension by using the Grassberger-Procaccia method. We found that at the transition the system exhibits a very complex behavior showing an exponential divergence of the trajectories corresponding to a positive Lyapunov exponent and a noninteger value of the correlation dimension. These results turn out to be linked to a physical interpretation. The Lyapunov exponents are in agreement with the model by Akhiezer et al. [Phys. Rep. 203, 289 (1991)], based on the equivalence between the ion motion along the crystal plane described as a "string of strings" and the "kicked" rotator. The nonintegral value of the correlation dimension can be explained by the nonconservation of transverse energy at the transition.

  4. Transport and localization in a topological phononic lattice with correlated disorder

    NASA Astrophysics Data System (ADS)

    Ong, Zhun-Yong; Lee, Ching Hua

    2016-10-01

    Recently proposed classical analogs of topological insulators in phononic lattices have the advantage of much more accessible experimental realization compared to conventional materials. Drawn to their potential practical structural applications, we investigate how disorder, which is generically nonnegligible in macroscopic realization, can attenuate the topologically protected edge (TPE) modes that constitute robust transmitting channels at zero disorder. We simulate the transmission of phonon modes in a quasi-one-dimensional classical lattice waveguide with mass disorder and show that the TPE mode transmission remains highly robust (Ξ ˜1 ) in the presence of uncorrelated disorder but diminishes when disorder is spatially correlated. This reduction in transmittance is attributed to the Anderson localization of states within the mass disorder domains. By contrast, non-TPE channels exhibit qualitatively different behavior, with spatial correlation in the mass disorder leading to significant transmittance reduction (enhancement) at low (high) frequencies. Our results demonstrate how TPE modes drastically modify the effect of spatial correlation on mode localization.

  5. Lattice calculation of coordinate-space vector and axial-vector current correlators in QCD

    NASA Astrophysics Data System (ADS)

    Tomii, M.; Cossu, G.; Fahy, B.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Noaki, J.; Jlqcd Collaboration

    2017-09-01

    We study the vector and axial-vector current correlators in perturbative and nonperturbative regimes of QCD. The correlators in Euclidean coordinate space are calculated on the lattice using the Möbius domain-wall fermion formulation at three lattice spacings covering 0.044-0.080 fm. The dynamical quark effects of 2 +1 light flavors are included. The sum V +A and the difference V -A of the vector (V ) and axial-vector (A ) current correlators calculated on the lattice after extrapolating to the physical point agree with those converted from the ALEPH experimental data of hadronic τ decays. The level of the agreement in the V +A channel is about 1.3 σ or smaller in the region of |x |≥0.4 fm , while that in the V -A channel is about 1.8 σ at |x |=0.74 fm and smaller at other distances. We also extract the chiral condensate from the short-distance correlators on the lattice using the partially conserved axial current relation. Its result extrapolated to the chiral and continuum limit is compatible with other estimates at low energies.

  6. Molecular dynamics simulation of nanochannel flows with effects of wall lattice-fluid interactions.

    PubMed

    Soong, C Y; Yen, T H; Tzeng, P Y

    2007-09-01

    In the present paper, molecular dynamics simulations are performed to explore the effects of wall lattice-fluid interactions on the hydrodynamic characteristics in nanochannels. Couette and Poiseuille flows of liquid argon with channel walls of face-centered cubic (fcc) lattice structure are employed as the model configurations. Truncated and shifted Lennard-Jones (LJ) 12-6 potentials for evaluations of fluid-fluid and wall-fluid interactions, and a nonlinear spring potential for wall-wall interaction, are used as interatomistic or molecular models. The hydrodynamics at various flow orientation angles with respect to channel walls of lattice planes (111), (100), and (110) are explored. The present work discloses that the effects of key parameters, such as wall density, lattice plane, flow orientation, and LJ interaction energy, have a very significant impact on the nanochannel flow characteristics. The related interfacial phenomena and the underlying physical mechanisms are explored and interpreted. These results are significant in the understanding of nanoscale hydrodynamics, as well as in various applications where an accurate nanoscale flow rate control is necessary.

  7. Toward a realistic low-field SSC lattice

    SciTech Connect

    Heifets, S.

    1985-10-01

    Three six-fold lattices for 3 T superferric SSC have been generated at TAC. The program based on the first order canonical transformation was used to compare lattices. On this basis the realistic race-track lattices were generated.

  8. Fluorescence imaging of lattice re-distribution on step-index direct laser written Nd:YAG waveguide lasers

    SciTech Connect

    Martínez de Mendívil, Jon; Pérez Delgado, Alberto; Lifante, Ginés; Jaque, Daniel; Ródenas, Airán; Benayas, Antonio; Aguiló, Magdalena; Diaz, Francesc; Kar, Ajoy K.

    2015-01-14

    The laser performance and crystalline micro-structural properties of near-infrared step-index channel waveguides fabricated inside Neodymium doped YAG laser ceramics by means of three-dimensional sub-picosecond pulse laser direct writing are reported. Fluorescence micro-mapping of the waveguide cross-sections reveals that an essential crystal lattice re-distribution has been induced after short pulse irradiation. Such lattice re-distribution is evidenced at the waveguide core corresponding to the laser written refractive index increased volume. The waveguides core surroundings also present diverse changes including slight lattice disorder and bi-axial strain fields. The step-index waveguide laser performance is compared with previous laser fabricated waveguides with a stress-optic guiding mechanism in absence of laser induced lattice re-distribution.

  9. Vibrons in finite size molecular lattices: a route for high-fidelity quantum state transfer at room temperature

    NASA Astrophysics Data System (ADS)

    Pouthier, Vincent

    2012-11-01

    A communication protocol is proposed in which vibron-mediated quantum state transfer takes place in a molecular lattice. We consider two distant molecular groups grafted on each side of the lattice. These groups form two quantum computers where vibrational qubits are implemented and received. The lattice defines the communication channel along which a vibron delocalizes and interacts with a phonon bath. Using quasi-degenerate perturbation theory, vibron-phonon entanglement is taken into account through the effective Hamiltonian concept. A vibron is thus dressed by a virtual phonon cloud whereas a phonon is clothed by virtual vibronic transitions. It is shown that three quasi-degenerate dressed states define the relevant paths followed by a vibron to tunnel between the computers. When the coupling between the computers and the lattice is judiciously chosen, constructive interference takes place between these paths. Phonon-induced decoherence is minimized and a high-fidelity quantum state transfer occurs over a broad temperature range.

  10. The QR-Decomposition Based Least-Squares Lattice Algorithm for Adaptive Filtering

    DTIC Science & Technology

    1990-07-01

    Copyright © Controller HMSO London 1990 THIS PAGE IS LEFT BLANI( INTENTIONALLY CONTENTS 1. INTRODUCION ...bring together the work of Lewis [9] and McWhiner[ 14]. Lewis began with the standard (covariance domain) multi-channel least squares lattice equations...decomposition. As the bulk of the calculation is exactly the computation of the reflection coefficients. Lewis pmoceeded no further with this re-formu

  11. Slanted, asymmetric microfluidic lattices as size-selective sieves for continuous particle/cell sorting.

    PubMed

    Yamada, Masumi; Seko, Wataru; Yanai, Takuma; Ninomiya, Kasumi; Seki, Minoru

    2017-01-17

    Hydrodynamic microfluidic platforms have been proven to be useful and versatile for precisely sorting particles/cells based on their physicochemical properties. In this study, we demonstrate that a simple lattice-shaped microfluidic pattern can work as a virtual sieve for size-dependent continuous particle sorting. The lattice is composed of two types of microchannels ("main channels" and "separation channels"). These channels cross each other in a perpendicular fashion, and are slanted against the macroscopic flow direction. The difference in the densities of these channels generates an asymmetric flow distribution at each intersection. Smaller particles flow along the streamline, whereas larger particles are filtered and gradually separated from the stream, resulting in continuous particle sorting. We successfully sorted microparticles based on size with high accuracy, and clearly showed that geometric parameters, including the channel density and the slant angle, critically affect the sorting behaviors of particles. Leukocyte sorting and monocyte purification directly from diluted blood samples have been demonstrated as biomedical applications. The presented system for particle/cell sorting would become a simple but versatile unit operation in microfluidic apparatus for chemical/biological experiments and manipulations.

  12. Effective lattice model for the collective modes in a Fermi liquid with spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Kumar, Abhishek; Maslov, Dmitrii L.

    2017-04-01

    A Fermi liquid (FL) with spin-orbit coupling (SOC) supports a special type of collective modes—chiral spin waves—which are oscillations of magnetization that occur even in the absence of the external magnetic field. We study the chiral spin waves of a two-dimensional FL in the presence of both the Rashba and Dresselhaus types of SOC and also subject to the in-plane magnetic field. We map the system of coupled kinetic equations for the angular harmonics of the occupation number onto an effective one-dimensional tight-binding model, in which the lattice sites correspond to angular-momentum channels. Linear-in-momentum SOC ensures that the effective tight-binding model has only nearest-neighbor hopping on a bipartite lattice. In this language, the continuum of spin-flip particle-hole excitations becomes a conduction band of the lattice model, whereas electron-electron interaction, parametrized by harmonics of the Landau function, is mapped onto lattice defects of both on-site and bond type. The collective modes correspond to bound states formed by such defects. All the features of the collective-mode spectrum receive natural explanation in the lattice picture as resulting from the competition between on-site and bond defects.

  13. The I=2 ππ S-wave Scattering Phase Shift from Lattice QCD

    DOE PAGES

    Beane, S. R.; Chang, E.; Detmold, W.; ...

    2012-02-16

    The π+π+ s-wave scattering phase-shift is determined below the inelastic threshold using Lattice QCD. Calculations were performed at a pion mass of mπ ≈ 390 MeV with an anisotropic nf = 2+1 clover fermion discretization in four lattice volumes, with spatial extent L ≈ 2.0, 2.5, 3.0 and 3.9 fm, and with a lattice spacing of bs ≈ 0.123 fm in the spatial direction and bt bs/3.5 in the time direction. The phase-shift is determined from the energy-eigenvalues of π+π+ systems with both zero and non-zero total momentum in the lattice volume using Luscher's method. Our calculations are precise enoughmore » to allow for a determination of the threshold scattering parameters, the scattering length a, the effective range r, and the shape-parameter P, in this channel and to examine the prediction of two-flavor chiral perturbation theory: mπ2 a r = 3+O(mπ2/Λχ2). Chiral perturbation theory is used, with the Lattice QCD results as input, to predict the scattering phase-shift (and threshold parameters) at the physical pion mass. Our results are consistent with determinations from the Roy equations and with the existing experimental phase shift data.« less

  14. A Review of Nucleon Spin Calculations in Lattice QCD

    SciTech Connect

    Huey-Wen Lin

    2009-08-01

    We review recent progress on lattice calculations of nucleon spin structure, including the parton distribution functions, form factors, generalization parton distributions, and recent developments in lattice techniques.

  15. Electron channeling radiation experiments at very high electron bunch charges

    SciTech Connect

    Carrigan, R.A. Jr.; Freudenberger, J.; Fritzler, S.; Genz, H.; Richter, A.; Ushakov, A.; Zilges, A.; Sellschop, J.P.F.

    2003-12-01

    Plasmas offer the possibility of high acceleration gradients. An intriguing suggestion is to use the higher plasma densities possible in solids to get extremely high gradients. Although solid-state plasmas might produce high gradients they would pose daunting problems. Crystal channeling has been suggested as one mechanism to address these challenges. There is no experimental or theoretical guidance on channeling for intense electron beams. A high-density plasma in a crystal lattice could quench the channeling process. An experiment has been carried out at the Fermilab NICADD Photoinjector Laboratory to observe electron channeling radiation at high bunch charges. An electron beam with up to 8 nC per electron bunch was used to investigate the electron-crystal interaction. No evidence was found of quenching of channeling at charge densities two orders of magnitude larger than that in earlier experiments.

  16. Studying defects in the silicon lattice using CCDs

    NASA Astrophysics Data System (ADS)

    Hall, D. J.; Murray, N. J.; Gow, J. P. D.; Wood, D.; Holland, A.

    2014-12-01

    Silicon has long been the material of choice for detectors for many applications, from space astronomy to synchrotron research. When operating in space, or within a synchrotron or other accelerator, the detector can be subjected to a harsh radiation environment. The presence of these high energy electrons, protons and gammas can lead to radiation-induced damage within the silicon lattice of the detector, creating further defects or ``traps'' in addition to any defects intrinsic to the lattice. Charge-Coupled Devices (CCDs) have been used for many years to populate the focal planes of space telescopes, with recent examples ranging from the Hubble Space Telescope to the more recently launched ESA Gaia mission. The radiation environment in such missions is often dominated by high-energy protons, and leads to traps which act to capture electrons from signal charge packets as they are transferred through the device. Any captured electrons are then released later in time, with this time determined by the emission time constant of the trap species in question. The repeated capture and release of signal as it is transferred through the CCD produces a ``smearing'' effect, resulting in a change in shape of the objects imaged. This change in shape is not only undesirable, but has particular importance to future applications such as the ESA Euclid mission, in which the subtle shape changes due to weak gravitational lensing are to be measured. In order to correct for any radiation damage present in a CCD, one must be able to produce a model that accurately represents the transfer of charge through a device containing such traps. While current models are often based on fits to observed data, it is now highly desirable to be able to actively predict the effects of any radiation on the device through a deeper understanding of the defects present in the lattice, at a sub-pixel, single-trap level. However, currently our understanding of defects within silicon has been based largely

  17. Two-nucleon higher partial-wave scattering from lattice QCD

    NASA Astrophysics Data System (ADS)

    Berkowitz, Evan; Kurth, Thorsten; Nicholson, Amy; Joó, Bálint; Rinaldi, Enrico; Strother, Mark; Vranas, Pavlos M.; Walker-Loud, André

    2017-02-01

    We present a determination of nucleon-nucleon scattering phase shifts for ℓ ≥ 0. The S, P, D and F phase shifts for both the spin-triplet and spin-singlet channels are computed with lattice Quantum ChromoDynamics. For ℓ > 0, this is the first lattice QCD calculation using the Lüscher finite-volume formalism. This required the design and implementation of novel lattice methods involving displaced sources and momentum-space cubic sinks. To demonstrate the utility of our approach, the calculations were performed in the SU (3)-flavor limit where the light quark masses have been tuned to the physical strange quark mass, corresponding to mπ =mK ≈ 800 MeV. In this work, we have assumed that only the lowest partial waves contribute to each channel, ignoring the unphysical partial wave mixing that arises within the finite-volume formalism. This assumption is only valid for sufficiently low energies; we present evidence that it holds for our study using two different channels. Two spatial volumes of V ≈(3.5 fm) 3 and V ≈(4.6 fm) 3 were used. The finite-volume spectrum is extracted from the exponential falloff of the correlation functions. Said spectrum is mapped onto the infinite volume phase shifts using the generalization of the Lüscher formalism for two-nucleon systems.

  18. Duality analysis on random planar lattices.

    PubMed

    Ohzeki, Masayuki; Fujii, Keisuke

    2012-11-01

    The conventional duality analysis is employed to identify a location of a critical point on a uniform lattice without any disorder in its structure. In the present study, we deal with the random planar lattice, which consists of the randomized structure based on the square lattice. We introduce the uniformly random modification by the bond dilution and contraction on a part of the unit square. The random planar lattice includes the triangular and hexagonal lattices in extreme cases of a parameter to control the structure. A modern duality analysis fashion with real-space renormalization is found to be available for estimating the location of the critical points with a wide range of the randomness parameter. As a simple test bed, we demonstrate that our method indeed gives several critical points for the cases of the Ising and Potts models and the bond-percolation thresholds on the random planar lattice. Our method leads to not only such an extension of the duality analyses on the classical statistical mechanics but also a fascinating result associated with optimal error thresholds for a class of quantum error correction code, the surface code on the random planar lattice, which is known as a skillful technique to protect the quantum state.

  19. Dynamic Behavior of Engineered Lattice Materials

    PubMed Central

    Hawreliak, J. A.; Lind, J.; Maddox, B.; Barham, M.; Messner, M.; Barton, N.; Jensen, B. J.; Kumar, M.

    2016-01-01

    Additive manufacturing (AM) is enabling the fabrication of materials with engineered lattice structures at the micron scale. These mesoscopic structures fall between the length scale associated with the organization of atoms and the scale at which macroscopic structures are constructed. Dynamic compression experiments were performed to study the emergence of behavior owing to the lattice periodicity in AM materials on length scales that approach a single unit cell. For the lattice structures, both bend and stretch dominated, elastic deflection of the structure was observed ahead of the compaction of the lattice, while no elastic deformation was observed to precede the compaction in a stochastic, random structure. The material showed lattice characteristics in the elastic response of the material, while the compaction was consistent with a model for compression of porous media. The experimental observations made on arrays of 4 × 4 × 6 lattice unit cells show excellent agreement with elastic wave velocity calculations for an infinite periodic lattice, as determined by Bloch wave analysis, and finite element simulations. PMID:27321697

  20. Controlling quantum dot emission by plasmonic nanoarrays.

    PubMed

    Guo, R; Derom, S; Väkeväinen, A I; van Dijk-Moes, R J A; Liljeroth, P; Vanmaekelbergh, D; Törmä, P

    2015-11-02

    Metallic nanoparticle arrays support localized surface plasmon resonances (LSPRs) and propagating surface lattice resonances (SLRs). We study the control of quantum dot (QD) emission coupled to the optical modes of silver nanoparticle arrays, both experimentally and numerically. With a hybrid lithography-functionalization method, the QDs are deposited in the vicinity of the nanoparticles. Directionality and enhancement of the emission are observed in photoluminescence spectra and fluorescence lifetime measurements, respectively. Similar features are also demonstrated in the numerical simulations. The tunable emission of this type of hybrid structures could lead to potential applications in light sources.