Quasi-particle properties in a quasi-two-dimensional electron liquid
Indian Academy of Sciences (India)
R Asgari; B Tanatar
2008-02-01
We consider the quasi-particle properties such as the effective mass and spin susceptibility of quasi-two-dimensional electron systems. The finite quantum well width effects are incorporated into the local-field factors that describe the charge and spin correlations. We employ the Fermi-hypernetted chain formalism in conjunction with fluctuation-dissipation theorem to obtain the local-field factors. Our results are in good agreement with recent experiments.
Quasi-particle vortex scattering in UPt{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Suderow, H.; Huxley, A. [CEA Centre des Etudes Nucleaires de Grenoble, Grenoble (France). DRFMC; Aubin, H.; Behnia, K. [Laboratoire de Physique des Solides (CNRS), Universite Paris-Sud, 91405, Orsay (France)
1997-09-08
We present a study of thermal conductivity in the superconducting phase of the heavy fermion superconductor UPt{sub 3}. The angular dependence of the thermal conductivity shows a cosine-square law when the magnetic field rotates in the basal plane. For a field rotating out of the basal plane, however, our results present features which can not be explained through our current conventional picture for vortex scattering of heat-carrying quasi-particles. (orig.).
Particle Dynamics under Quasi-linear Interaction with Electromagnetic Waves
Energy Technology Data Exchange (ETDEWEB)
Castejon, F.; Eguilior, S.
2003-07-01
Langevin equations for quasi-linear wave particle interaction are obtained taking advantage of the unique vocal equivalence between Fokker-Plank equation and the former ones. Langevin equations are solved numerically and, hence, the evolution of a single particle embedded in an electromagnetic field in momentum space is obtained. The equations are relativistic and valid for any wave. It is also shown that the stochastic part of the equations is negligible in comparison with the deterministic term, except for the momentum to the resonance condition for the main parallel refractive index. (Author) 24 refs.
Selection of quasi-monodisperse super-micron aerosol particles
Rösch, Michael; Pfeifer, Sascha; Wiedensohler, Alfred; Stratmann, Frank
2014-05-01
Size-segregated quasi monodisperse particles are essential for e.g. fundamental research concerning cloud microphysical processes. Commonly a DMA (Differential Mobility Analyzer) is used to produce quasi-monodisperse submicron particles. Thereto first, polydisperse aerosol particles are bipolarly charged by a neutralizer, and then selected according to their electrical mobility with the DMA [Knutson et al. 1975]. Selecting a certain electrical mobility with a DMA results in a particle size distribution, which contains singly charged particles as well as undesired multiply charged larger particles. Often these larger particles need to either be removed from the generated aerosol or their signals have to be corrected for in the data inversion and interpretation process. This problem becomes even more serious when considering super-micron particles. Here we will present two different techniques for generating quasi-monodisperse super-micron aerosol particles with no or only an insignificant number of larger sized particles being present. First, we use a combination of a cyclone with adjustable aerodynamic cut-off diameter and our custom-built Maxi-DMA [Raddatz et al. 2013]. The cyclone removes particles larger than the desired ones prior to mobility selection with the DMA. This results in a reduction of the number of multiply charged particles of up to 99.8%. Second, we utilize a new combination of cyclone and PCVI (Pumped Counterflow Virtual Impactor), which is based on purely inertial separation and avoids particle charging. The PCVI instrument was previously described by Boulter et al. (2006) and Kulkarni et al. (2011). With our two setups we are able to produce quasi-monodisperse aerosol particles in the diameter range from 0.5 to 4.4 µm without a significant number of larger undesired particles being present. Acknowledgements: This work was done within the framework of the DFG funded Ice Nucleation research UnIT (INUIT, FOR 1525) under WE 4722/1-1. References
One-dimensional quasi-relativistic particle in the box
Kaleta, Kamil; Malecki, Jacek
2011-01-01
Two-term Weyl-type asymptotic law for the eigenvalues of one-dimensional quasi-relativistic Hamiltonian (-h^2 c^2 d^2/dx^2 + m^2 c^4)^(1/2) + V_well(x) (the Klein-Gordon square-root operator with electrostatic potential) with the infinite square well potential V_well(x) is given: the n-th eigenvalue is equal to (n pi/2 - pi/8) h c/a + O(1/n), where 2a is the width of the potential well. Simplicity of eigenvalues is proved. Some L^2 and L^infinity properties of eigenfunctions are also studied. Eigenvalues represent energies of a `massive particle in the box' quasi-relativistic model.
Two-particle correlations via quasi-deterministic analyzer model
Dalton, B J
2001-01-01
We introduce a quasi-deterministic eigenstate transition model of analyzers in which the final eigenstate is selected by initial conditions. We combine this analyzer model with causal spin coupling to calculate both proton-proton and photon-photon correlations, one particle pair at a time. The calculated correlations exceed the Bell limits and show excellent agreement with the measured correlations of [M. Lamehi-Rachti and W. Mittig, Phys. Rev. D 14 (10), 2543 (1976)] and [ A. Aspect, P. Grangier and G. Rogers, Phys. Rev. Lett. 49 91 (1982)] respectively. We discuss why this model exceeds the Bell type limits.
Towards thermodynamics of the quark quasi-particles
Molodtsov, S V
2011-01-01
Some features of hot and dense gas of quarks which are considered as the quasi-particles of the model Hamiltonian with four-fermion interaction are studied. Being adapted to the Nambu-Jona-Lasinio model this approach allows us to accommodate a phase transition similar to the nuclear liquid-gas one at the proper scale and to argue an existence of the mixed phase of vacuum and normal baryonic matter as a plausible scenario of chiral symmetry (partial) restoration. Analyzing the transition layer between two phases we estimate the surface tension coefficient and discuss the possibility of quark droplet formation.
Quasi-particle injection into YBa2Cu3O7-δ micro-bridge
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Several types of quasi-particle injections into YBa2Cu3O70-δ (YBCO) micro-bridge have been studied, re-vealing the quasi-particle non-equilibrium effect, the current superposition effect and the heating effect. The current gain's dependence on temperatures indicates that supercon-ductivity of YBCO is really suppressed by quasi-particle injection. We propose a new type of quasi-particle injection which turns out to be a promising candidate for interface between superconductor and semiconductor circuits.
Baryon number fluctuations in quasi-particle model
Energy Technology Data Exchange (ETDEWEB)
Zhao, Ameng [Southeast University Chengxian College, Department of Foundation, Nanjing (China); Luo, Xiaofeng [Central China Normal University, Key Laboratory of Quark and Lepton Physics (MOE), Institute of Particle Physics, Wuhan (China); Zong, Hongshi [Nanjing University, Department of Physics, Nanjing (China); Joint Center for Particle, Nuclear Physics and Cosmology, Nanjing (China); Institute of Theoretical Physics, CAS, State Key Laboratory of Theoretical Physics, Beijing (China)
2017-04-15
Baryon number fluctuations are sensitive to the QCD phase transition and the QCD critical point. According to the Feynman rules of finite-temperature field theory, we calculated various order moments and cumulants of the baryon number distributions in the quasi-particle model of the quark-gluon plasma. Furthermore, we compared our results with the experimental data measured by the STAR experiment at RHIC. It is found that the experimental data can be well described by the model for the colliding energies above 30 GeV and show large discrepancies at low energies. This puts a new constraint on the qQGP model and also provides a baseline for the QCD critical point search in heavy-ion collisions at low energies. (orig.)
Baryon Number Fluctuations in Quasi-particle Model
Zhao, Ameng; Zong, Hongshi
2016-01-01
Baryon number fluctuations are sensitive to the QCD phase transition and QCD critical point. According to the Feynman rules of finite-temperature field theory, we calculated various order moments and cumulants of the baryon number distributions in the quasi-particle model of quark gluon plasma. Furthermore, we compared our results with the experimental data measured by the STAR experiment at RHIC. It is found that the experimental data can be well described by the model for the colliding energies above 30 GeV and show large discrepancies at low energies. It can put new constraint on qQGP model and also provide a baseline for the QCD critical point search in heavy-ion collisions at low energies.
Particle dynamics inside a quasi-isochronous storage ring
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y. [Fermi National Accelerator Lab., Batavia, IL (United States); Bai, M.; Brabson, B.; Chu, C.M.; Kang, X.; Jeon, D.; Lee, S.Y.; Riabko, A.; Zhao, X. [Indiana Univ., Bloomington, IN (United States). Dept. of Physics
1996-10-01
Quasi-isochronous {alpha}-like bucket can be important in providing ultra short bunches. the instability of a bunch inside the bucket is found to be severely affected by rf phase modulation. The synchrotron tune drops to zero at the bucket edge very rapidly, indicating the possibility of a thick chaotic layer due to overlapping of resonance islands. The approach to chaos comes from a sequence of bifurcation into 2:1 parametric resonances. When quantum excitation is included in addition to radiation damping, the instability is worsened. the steady-state particle distribution in the longitudinal phase space is Gaussian in the phase coordinate and non-Gaussian in the momentum coordinate, unless the bunch is small. The size of the bunch is governed only bye the ``thermal energy`` {ital E{sub th}} = D{sup 2}/2A, where D and A are, respectively, the normalized diffusion and damping coefficients. The quantum lifetime of the particle bunch, for the D and A that have been enhanced by the smallness of the phase- slip factor, is studied and turns out to be much longer than expected. Phase modulation tends to enhance quantum diffusion at high frequencies, but leads to stochastic resonances instead at low frequencies.
Pseudolocalized Three-dimensional Solitary Waves as Quasi-Particles
Christov, C I
2012-01-01
A higher-order dispersive equation is introduced as a candidate for the governing equation of a field theory. A new class of solutions of the three-dimensional field equation are considered, which are not localized functions in the sense of the integrability of the square of the profile over an infinite domain. For the new type of solutions, the gradient and/or the Hessian/Laplacian are square integrable. In the linear limiting case, analytical expression for the pseudolocalized solution is found and the method of variational approximation is applied to find the dynamics of the centers of the quasi-particles (QPs) corresponding to these solutions. A discrete Lagrangian can be derived due to the localization of the gradient and the Laplacian of the profile. The equations of motion of the QPs are derived from the discrete Lagrangian. The pseudomass ("wave mass") of a QP is defined as well as the potential of interaction. The most important trait of the new QPs is that at large distances, the force of attraction...
A quasi-particle description of $(2+1)$- flavor lattice QCD equation of state
Chandra, Vinod
2011-01-01
A quasi-particle model has been employed to describe the $(2+1)$-flavor lattice QCD equation of state with physical quark masses. The interaction part of the equation of state has been mapped to the effective fugacities of otherwise non-interacting quasi-gluons and quasi-quarks. The mapping is found to be exact for the equation of state. The model leads to non-trivial dispersion relations for quasi-partons. The dispersion relations, effective quasi-particle number densities, and trace anomaly have been investigated employing the model. A Virial expansion for the EOS has further been obtained to investigate the role of interactions in quark-gluon plasma (QGP). Finally, Debye screening in QGP has been studied employing the model.
Explicit Expression of Seniority Particle Operator and Its Properties in Quasi-spin Theory
Institute of Scientific and Technical Information of China (English)
ZHANG Bo; LU Da-Hai; DENG Wei-Zhen; CHEN Xiao-Lin
2006-01-01
The explicit expression of the seniority particle operator and its properties in the quasi-spin theory of nuclear physics is presented in this paper. The seniority particle operator can be used to construct D-pair in the microscopic theory of interacting boson model to avoid the seniority mixing problem.
Niu, Y F; Vigezzi, E; Bai, C L; Sagawa, H
2016-01-01
We propose a self-consistent quasi-particle random phase approximation (QRPA) plus quasi-particle-vibration coupling (QPVC) model with Skyrme interactions to describe the width and the line shape of giant resonances in open-shell nuclei, in which the effect of superfluidity should be taken into account in both the ground state and the excited states. We apply the new model to the Gamow-Teller resonance in the superfluid nucleus $^{120}$Sn, including both the isoscalar spin-triplet and the isovector spin-singlet pairing interactions. The strength distribution in $^{120}$Sn is well reproduced and the underlying microscopic mechanisms, related to QPVC and also to isoscalar pairing, are analyzed in detail.
Biased impurity tunneling current emission spectrum in the presence of quasi-particle interaction
Maslova, N. S.; Arseyev, P. I.; Mantsevich, V. N.
2016-09-01
We performed theoretical investigations of the tunneling current noise spectra through single-level impurity in the presence of quasi-particle (electron-phonon) interaction by means of the non-equilibrium Green function formalism. We demonstrated a fundamental link between quantum noise in tunneling contact and light emission processes. We calculated tunneling current noise spectra through a single level impurity atom both in the presence and in the absence of quasi-particle interaction for a finite bias voltage and identified it as a source of experimentally observed light emission from bias STM contacts. The results turn out to be sensitive to the tunneling contact parameters. Our findings provide important insight into the nature of non-equilibrium electronic transport in tunneling junctions with quasi-particle interaction.
Quasi-particle Continuum and Resonances in the Hartree-Fock-Bogoliubov Theory
Energy Technology Data Exchange (ETDEWEB)
Pei, J. C. [University of Tennessee, Knoxville (UTK) & Oak Ridge National Laboratory (ORNL); Kruppa, Andras Tibor [ORNL; Nazarewicz, Witold [ORNL
2011-01-01
The quasi-particle energy spectrum of the Hartree-Fock-Bogoliubov (HFB) equations contains discrete bound states, resonances, and non-resonant continuum states. We study the structure of the unbound quasi-particle spectrum of weakly bound nuclei within several methods that do not rely on imposing scattering or outgoing boundary conditions. Various approximations are examined to estimate resonance widths. It is shown that the stabilization method works well for all HFB resonances except for very narrow ones. The Thomas-Fermi approximation to the non-resonant continuum has been shown to be very effective, especially for coordinate-space HFB calculations in large boxes that involve huge amounts of discretized quasi-particle continuum states.
On the decrease in charge radii of multi-quasi particle isomers
Energy Technology Data Exchange (ETDEWEB)
Bissell, M.L. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Flanagan, K.T. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Gardner, M.D. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Avgoulea, M. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Billowes, J. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Campbell, P. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Cheal, B. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom)]. E-mail: bc@mags.ph.man.ac.uk; Eronen, T. [Department of Physics, University of Jyvaeskylae, PB 35 (YFL) FIN-40351 Jyvaeskylae (Finland); Forest, D.H. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Huikari, J. [Department of Physics, University of Jyvaeskylae, PB 35 (YFL) FIN-40351 Jyvaeskylae (Finland); Jokinen, A. [Department of Physics, University of Jyvaeskylae, PB 35 (YFL) FIN-40351 Jyvaeskylae (Finland); Moore, I.D. [Department of Physics, University of Jyvaeskylae, PB 35 (YFL) FIN-40351 Jyvaeskylae (Finland); Nieminen, A. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Penttilae, H. [Department of Physics, University of Jyvaeskylae, PB 35 (YFL) FIN-40351 Jyvaeskylae (Finland); Rinta-Antila, S. [Department of Physics, University of Jyvaeskylae, PB 35 (YFL) FIN-40351 Jyvaeskylae (Finland); Tordoff, B. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Tungate, G. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Aystoe, J. [Department of Physics, University of Jyvaeskylae, PB 35 (YFL) FIN-40351 Jyvaeskylae (Finland)
2007-02-15
We report changes in mean-square charge radii, {delta}
Quasi-particle interference of heavy fermions in resonant x-ray scattering
Gyenis, András; da Silva Neto, Eduardo H.; Sutarto, Ronny; Schierle, Enrico; He, Feizhou; Weschke, Eugen; Kavai, Mariam; Baumbach, Ryan E.; Thompson, Joe D.; Bauer, Eric D.; Fisk, Zachary; Damascelli, Andrea; Yazdani, Ali; Aynajian, Pegor
2016-01-01
Resonant x-ray scattering (RXS) has recently become an increasingly important tool for the study of ordering phenomena in correlated electron systems. Yet, the interpretation of RXS experiments remains theoretically challenging because of the complexity of the RXS cross section. Central to this debate is the recent proposal that impurity-induced Friedel oscillations, akin to quasi-particle interference signals observed with a scanning tunneling microscope (STM), can lead to scattering peaks in RXS experiments. The possibility that quasi-particle properties can be probed in RXS measurements opens up a new avenue to study the bulk band structure of materials with the orbital and element selectivity provided by RXS. We test these ideas by combining RXS and STM measurements of the heavy fermion compound CeMIn5 (M = Co, Rh). Temperature- and doping-dependent RXS measurements at the Ce-M4 edge show a broad scattering enhancement that correlates with the appearance of heavy f-electron bands in these compounds. The scattering enhancement is consistent with the measured quasi-particle interference signal in the STM measurements, indicating that the quasi-particle interference can be probed through the momentum distribution of RXS signals. Overall, our experiments demonstrate new opportunities for studies of correlated electronic systems using the RXS technique.
Quasi-linear wave-particle interactions in the earth's radiation belts
Villalon, Elena; Silevitch, Michel B.; Rothwell, Paul L.; Burke, William J.
1989-11-01
A self-consistent theory on the interaction of magnetospheric particles with ducted electromagnetic cyclotron waves is presented. The main contribution is to calculate the coupling coefficients for the ray equations describing the temporal evolution of the cyclotron instability. These are obtained within the framework of quasi-linear interaction of waves and particles. A set of equations is derived based on the Fokker-Planck theory of pitch angle diffusion, describing the evolution time of the number of particles in the flux tube and the energy density of waves for the interaction of Alfven waves with protons and of whistler waves with electrons. The coupling coefficients are obtained, based on a quasi-linear analysis after averaging over the particle bounce motion. It is found that the equilibrium solutions for particle fluxes and wave amplitudes are stable under small local perturbations. The reflection of the waves in the ionosphere is discussed. A stability analysis around the equilibrium solutions for precipitating particle fluxes and wave intensity indicates that an actively excited ionosphere can cause the development of explosive instabilities.
Quasi-particle Specific Heats for the Crystalline Color Superconducting Phase of QCD
Casalbuoni, Roberto; Mannarelli, M; Nardulli, Giuseppe; Ruggieri, Marco; Stramaglia, S
2003-01-01
We calculate the specific heats of quasi-particles of two-flavor QCD in its crystalline phases for low temperature. We show that for the different crystalline structures considered here there are gapless modes contributing linearly in temperature to the specific heat. We evaluate also the phonon contributions which are cubic in temperature. These features might be relevant for compact stars with an inner shell in a color superconducting crystalline phase.
Quasi-particle specific heats for the crystalline color superconducting phase of QCD
Energy Technology Data Exchange (ETDEWEB)
Casalbuoni, R.; Gatto, R.; Mannarelli, M.; Nardulli, G.; Ruggieri, M.; Stramaglia, S
2003-11-27
We calculate the specific heats of quasi-particles of two-flavor QCD in its crystalline phases for low temperature. We show that for the different crystalline structures considered here there are gapless modes contributing linearly in temperature to the specific heat. We evaluate also the phonon contributions which are cubic in temperature. These features might be relevant for compact stars with an inner shell in a color superconducting crystalline phase.
Quasi-particles and effective mean field in strongly interacting matter
Energy Technology Data Exchange (ETDEWEB)
Levai, P. [MTA KFKI RMKI, POB 49., Budapest 114, 1525 (Hungary); Cyclotron Institute and Physics Department, Texas A and M University, College Station, TX 77843 (United States); Ko, C.M. [Cyclotron Institute and Physics Department, Texas A and M University, College Station, TX 77843 (United States)
2010-03-01
We introduce a quasi-particle model of strongly interacting quark-gluon matter and explore the possible connection to an effective field theoretical description consisting of a scalar sigma field by introducing a dynamically generated mass, M(sigma), and a self-consistently determined interaction term, B(sigma). We display a possible connection between the two types of effective description, using the Friedberg-Lee model.
Quasi-particles and effective mean field in strongly interacting matter
Lévai, P.; Ko, C. M.
2010-03-01
We introduce a quasi-particle model of strongly interacting quark-gluon matter and explore the possible connection to an effective field theoretical description consisting of a scalar σ field by introducing a dynamically generated mass, M(σ), and a self-consistently determined interaction term, B(σ). We display a possible connection between the two types of effective description, using the Friedberg-Lee model.
Equation of State of the Quark Gluon Plasma within the Quasi-particle Approach
Begun, Viktor V; Mogilevsky, Oleg A
2010-01-01
We propose simple analytical form of the quark-gluon plasma (QGP) equation of state (EoS) based on a quasi-particle approach. This new EoS satisfies all qualitative features observed in the lattice QCD calculations and gives a good quantitative description of the lattice results in SU(3) gluodynamics. The suggested EoS opens up new possibilities for hydrodynamic and kinetic phenomenological applications in the studies of the QGP.
Quasi-particles ultrafastly releasing kink bosons to form Fermi arcs in a cuprate superconductor.
Ishida, Y; Saitoh, T; Mochiku, T; Nakane, T; Hirata, K; Shin, S
2016-01-01
In a conventional framework, superconductivity is lost at a critical temperature (Tc) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-Tc cuprates, it is still unknown how superconductivity vanishes at Tc. We provide evidence that the so-called ≲ 70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O(8+δ) and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above Tc.
Quasi-two-dimensional complex plasma containing spherical particles and their binary agglomerates
Chaudhuri, M; Nosenko, V; Thomas, H M
2015-01-01
A new type of quasi-two-dimensional complex plasma system was observed which consisted of monodisperse microspheres and their binary agglomerations (dimers). The particles and their dimers levitated in a plasma sheath at slightly different heights and formed two distinct sublayers. The sys- tem did not crystallize and may be characterized as disordered solid. The dimers were identified based on their characteristic appearance in defocused images, i.e., rotating interference fringe pat- terns. The in-plane and inter-plane particle separations exhibit nonmonotonic dependence on the discharge pressure which agrees well with theoretical predictions.
A non-abelian quasi-particle model for gluon plasma
Politis, E. P.; Tsagkarakis, C. E.; Diakonos, F. K.; Maintas, X. N.; Tsapalis, A.
2016-12-01
We propose a quasi-particle model for the thermodynamic description of the gluon plasma which takes into account non-abelian characteristics of the gluonic field. This is accomplished utilizing massive non-linear plane wave solutions of the classical equations of motion with a variable mass parameter, reflecting the scale invariance of the Yang-Mills Lagrangian. For the statistical description of the gluon plasma we interpret these non-linear waves as quasi-particles with a temperature dependent mass distribution. Quasi-Gaussian distributions with a common variance but different temperature dependent mean masses for the longitudinal and transverse modes are employed. We use recent Lattice results to fix the mean transverse and longitudinal masses while the variance is fitted to the equation of state of pure SU (3) on the Lattice. Thus, our model succeeds to obtain both a consistent description of the gluon plasma energy density as well as a correct behavior of the mass parameters near the critical point.
Nodal quasi-particles of the high-Tc superconductors as carriers of heat
Directory of Open Access Journals (Sweden)
K. Behnia
2006-09-01
Full Text Available In the quest for understanding correlated electrons, high-temperature superconductivity remains a formidable challenge and a source of insight. This paper briefly recalls the central achievement by the study of heat transport at low temperatures. At very low temperatures, nodal quasi-particles of the d-wave superconducting gap become the main carriers of heat. Their thermal conductivity is unaffected by disorder and reflects the fine structure of the superconducting gap. This finding had led to new openings in the exploration of other unconventional superconductors
Dissociation of heavy quarkonium in hot QCD medium in a quasi-particle model
Agotiya, Vineet K; Jamal, M Yousuf; Nilima, Indrani
2016-01-01
Following a recent work on the effective description of the equations of state for hot QCD obtained from a Hard thermal loop expression for the gluon self-energy, in terms of the quasi-gluons and quasi- quark/anti-quarks with respective effective fugacities, the dissociation process of heavy quarkonium in hot QCD medium has been investigated. This has been done by investigating the medium modification to a heavy quark potential. The medium modified potential has a quite different form (a long range Coulomb tail in addition to the usual Yukawa term) in contrast to the usual picture of Debye screening. The flavor dependence of the binding energies of the heavy quarkonia states and the dissociation temperature have been obtained by employing the debye mass for pure gluonic and full QCD case computed employing the quasi-particle picture. Thus estimated dissociation patterns of the charmonium and bottomonium states, considering Debye mass from different approaches in pure gluonic case and full QCD, have shown good...
Kuliev, I G
2002-01-01
One studied the effect of normal processes of electron-electron and phonon-phonon scattering on relaxation of quasi-particle pulse in nonequilibrium electron-phonon systems of degenerate semiconductors. One solved a system of kinetic equations for electron and phonon functions of distribution and calculated kinetic coefficients degeneration parameter. One analyzed the effect of normal processes of quasi-particle scattering on electric conductivity, thermo-emf and heat conductivity of degenerate semiconductors. One took account of redistribution of phonon pulse in N-processes of phonon-phonon scattering both inside every oscillating particle and between phonon different oscillating branches
Quasi-linear wave-particle interactions in the Earth's radiation belts
Energy Technology Data Exchange (ETDEWEB)
Villalon, E. (Center for Electromagnetics Research, Northeastern University, Boston, Massachusetts (USA)); Burke, W.J.; Rothwell, P.L. (Air Force Geophysics Laboratory, Hanscom Air Force Base, Massachusetts (USA)); Silevitch, M.B. (Center for Electromagnetic Research, Northeastern University, Boston, Massachusetts (USA))
1989-11-01
This paper studies the theory of gyroresonant interactions of energetic trapped electrons and protons in the Earth's radiation zones with ducted electromagnetic cyclotron waves. Substorm injected electrons in the mid-latitude regions interact with coherent VLF signals, such as whistler mode waves. Energetic protons may interact with narrow-band hydromagnetic (Alfven) waves. A set of equations is derived based on the Fokker-Planck theory of pitch angle diffusion. They describe the evolution in time of the number of particles in the flux tube and the energy density of waves, for the interaction of Alfven waves with protons and of whistler waves with electrons. The coupling coefficients are obtained based on a quasi-linear analysis after averaging over the particle bounce motion. It is found that the equilibrium solutions for particle fluxes and wave amplitudes are stable under small local perturbations. The reflection of the waves in the ionosphere is discussed. To efficiently dump the energetic particles from the radiation belts, the reflection coefficient must be very close to unity so waves amplitudes can grow to high values. Then, the precipitating particle fluxes may act as a positive feedback to raise the height integrated conductivity of the ionosphere which in turn, enhances the reflection of the waves. In addition, by heating the foot of the flux tube with high intensity, RF energy the mirroring properties of the ionosphere are also enhanced. The stability analysis around the equilibrium solutions for precipitating particle fluxes and wave intensity show that an actively excited ionosphere can cause the development of explosive instabilities. {copyright} American Geophysical Union 1989
Chakraborty, P
2016-01-01
In high energy heavy ion collisions, single particle distributions are distorted from their thermal equilibrium form due to gradients in the flow velocity. These are closely related to the formulas for the shear and bulk viscosities in the quasi-particle approximation. Distorted single particle distributions are now commonly used to calculate the emission of photons and dilepton pairs, and in the late stage to calculate the conversion of a continuous fluid to individual particles. In practice this is done only in a very approximate way. We show how it can be done rigorously in the quasi-particle approximation and illustrate it with the linear $\\sigma$ model at finite temperature for both the shear and bulk contributions.
Nakanishi-Ohno, Yoshinori; Haze, Masahiro; Yoshida, Yasuo; Hukushima, Koji; Hasegawa, Yukio; Okada, Masato
2016-09-01
We applied a method of compressed sensing to the observation of quasi-particle interference (QPI) by scanning tunneling microscopy/spectroscopy to improve efficiency and save measurement time. To solve an ill-posed problem owing to the scarcity of data, the compressed sensing utilizes the sparseness of QPI patterns in momentum space. We examined the performance of a sparsity-inducing algorithm called least absolute shrinkage and selection operator (LASSO), and demonstrated that LASSO enables us to recover a double-circle QPI pattern of the Ag(111) surface from a dataset whose size is less than that necessary for the conventional Fourier transformation method. In addition, the smallest number of data required for the recovery is discussed on the basis of cross validation.
Beyond the quasi-particle: stochastic domain wall dynamics in soft ferromagnetic nanowires
Hayward, T. J.; Omari, K. A.
2017-03-01
We study the physical origins of stochastic domain wall pinning in soft ferromagnetic nanowires using focused magneto-optic Kerr effect measurements and dynamic micromagnetic simulations. Our results illustrate the ubiquitous nature of these effects in Ni80Fe20 nanowires, and show that they are not only a result of the magnetisation history of the system (i.e. the magnetisation structure of the injected domain walls), and the onset of non-linear propagation dynamics above the Walker breakdown field, but also a complex interplay between the two. We show that this means that, while micromagnetics can be used to make qualitative predictions of the behaviour of domain walls at defect sites, making quantitative predictions is much more challenging. Together, our results reinforce the view that even in these simple pseudo-one dimensional nanomagnets, domain walls must be considered as complex, dynamically evolving objects rather than simple quasi-particles.
Lopes, Ilídio P; Silk, Joseph
2002-04-15
SNO measurements strongly constrain the central temperature of the Sun, to within a precision of much less than 1%. This result can be used to probe the parameter space of supersymmetric dark matter. In this first analysis we find a lower limit for the weakly interacting massive particle (WIMP) mass of 60 GeV. Furthermore, in the event that WIMPs create a quasi-isothermal core, they will produce a peculiar distribution of the solar neutrino fluxes measured on Earth. Typically, a WIMP with a mass of 100 GeV and annihilation cross section of 10(-34) cm(3)/sec will decrease the neutrino predictions, by up to 4% for the Cl, by 3% for the heavy water, and by 1% for the Ga detectors.
Institute of Scientific and Technical Information of China (English)
JU Guo-Xing; XIANG Yang; REN Zhong-Zhou
2006-01-01
The properties of the s-wave for a quasi-free particle with position-dependent mass (PDM) have been discussed in details. Differed from the system with constant mass in which the localization of the s-wave for the free quantum particle around the origin only occurs in two dimensions, the quasi-free particle with PDM can experience attractive forces in D dimensions except D=1 when its mass function satisfies some conditions. The effective mass of a particle varying with its position can induce effective interaction, which may be attractive in some cases. The analytical expressions of the eigenfunctions and the corresponding probability densities for the s-waves of the two- and three-dimensional systems with a special PDM are given, and the existences of localization around the origin for these systems are shown.
Self-Localized Quasi-Particle Excitation in Quantum Electrodynamics and Its Physical Interpretation
Directory of Open Access Journals (Sweden)
Ilya D. Feranchuk
2007-12-01
Full Text Available The self-localized quasi-particle excitation of the electron-positron field (EPF is found for the first time in the framework of a standard form of the quantum electrodynamics. This state is interpreted as the ''physical'' electron (positron and it allows one to solve the following problems: i to express the ''primary'' charge $e_0$ and the mass $m_0$ of the ''bare'' electron in terms of the observed values of $e$ and $m$ of the ''physical'' electron without any infinite parameters and by essentially nonperturbative way; ii to consider $mu$-meson as another self-localized EPF state and to estimate the ratio $m_mu/m$; iii to prove that the self-localized state is Lorentz-invariant and its energy spectrum corresponds to the relativistic free particle with the observed mass $m$; iv to show that the expansion in a power of the observed charge $e ll 1$ corresponds to the strong coupling expansion in a power of the ''primary'' charge $e^{-1}_0 sim e$ when the interaction between the ''physical'' electron and the transverse electromagnetic field is considered by means of the perturbation theory and all terms of this series are free from the ultraviolet divergence.
Quasi-Particle Degrees of Freedom versus the Perfect Fluid as Descriptors of the Quark-Gluon Plasma
Levy, L A Linden; Rosen, C; Steinberg, P
2007-01-01
Approaches for understanding the hydrodynamic flow of the hot and dense medium created in the collisions of relativistic heavy ions are discussed, focusing on their implications for scenarios where quasi-particles are assumed to carry the thermodynamic degrees of freedom. Well-defined quasi-particle degrees of freedom are in principle inconsistent with inviscid hydrodynamics, which implies a vanishing mean free path. However, quasi-particles may play a role as the density of the medium decreases. It is thus an open question whether the freeze-out of the fluid stage proceeds directly into hadrons, or via a fleeting intermediate state with effectively-free constituent quarks, which may well be identified with QCD quasi-particle degrees of freedom. The empirical observation of the ``$n_q$'' scaling of elliptic flow \\cite{Adare:2006ti} (the universality of $v_2/n_q$ as a function of $(m_{T}-m)/n_q$, where $n_q$ is the number of constituent quarks in the hadron) is scrutinized in detail. It is found that, at all t...
DEFF Research Database (Denmark)
Henneberg, Morten; Eriksen, René Lynge; Jørgensen, Bent
2015-01-01
Suspension of wear particles in gear oil with respect to the diversity of particle size combined with filter mechanisms has been analyzed. Coupling of wear modes from tribology is combined with particle size bins to show how a mathematical model can be expanded to include information gained from...... sensors that can segment particles into size bins. In order to establish boundary conditions for the model based on real data, a filtration test is included. Finally, the model is fitted to data from a gear in operation and differences between real data and the model are discussed. The findings show...... that particles less than 14 μm dominate the wear. Hence, it is concluded that abrasion dominate the wear, for the gear in operation, and it is concluded to be in quasi-stationary mode. The distribution of the particles is observed in conjunction with the particle quantity to determine a basis for normal...
Asymptotic-preserving Particle-In-Cell methods for the Vlasov-Maxwell system near quasi-neutrality
Degond, Pierre; Doyen, David
2015-01-01
In this article, we design Asymptotic-Preserving Particle-In-Cell methods for the Vlasov-Maxwell system in the quasi-neutral limit, this limit being characterized by a Debye length negligible compared to the space scale of the problem. These methods are consistent discretizations of the Vlasov-Maxwell system which, in the quasi-neutral limit, remain stable and are consistent with a quasi-neutral model (in this quasi-neutral model, the electric field is computed by means of a generalized Ohm law). The derivation of Asymptotic-Preserving methods is not straightforward since the quasi-neutral model is a singular limit of the Vlasov-Maxwell model. The key step is a reformulation of the Vlasov-Maxwell system which unifies the two models in a single set of equations with a smooth transition from one to another. As demonstrated in various and demanding numerical simulations, the Asymptotic-Preserving methods are able to treat efficiently both quasi-neutral plasmas and non-neutral plasmas, making them particularly we...
Degond, P.; Deluzet, F.; Doyen, D.
2017-02-01
In this article, we design Asymptotic-Preserving Particle-In-Cell methods for the Vlasov-Maxwell system in the quasi-neutral limit, this limit being characterized by a Debye length negligible compared to the space scale of the problem. These methods are consistent discretizations of the Vlasov-Maxwell system which, in the quasi-neutral limit, remain stable and are consistent with a quasi-neutral model (in this quasi-neutral model, the electric field is computed by means of a generalized Ohm law). The derivation of Asymptotic-Preserving methods is not straightforward since the quasi-neutral model is a singular limit of the Vlasov-Maxwell model. The key step is a reformulation of the Vlasov-Maxwell system which unifies the two models in a single set of equations with a smooth transition from one to another. As demonstrated in various and demanding numerical simulations, the Asymptotic-Preserving methods are able to treat efficiently both quasi-neutral plasmas and non-neutral plasmas, making them particularly well suited for complex problems involving dense plasmas with localized non-neutral regions.
Thermodynamics and higher order moments in SU(3) linear $\\sigma$-model with gluonic quasi-particles
Tawfik, Abdel Nasser
2014-01-01
In framework of linear $\\sigma$-model (LSM) with three quark flavors, the chiral phase-diagram at finite temperature and density is investigated. At temperatures higher than the critical temperature ($ T_c $), we added to LSM the gluonic sector from the quasi-particle model (QPM), which assumes that the interacting gluons in the strongly interacting matter, the quark-gluon plasma (QGP), are phenomenologically the same as non-interacting massive quasi-particles. The dependence of the chiral condensates of strange and non-strange quarks on temperature and chemical potential is analysed. Then, we have calculated the thermodynamics in the new approach (combination of LSM and QPM). Confronting the results with recent lattice QCD simulations shows an excellent agreement in almost all thermodynamic quantities. The first and second order moments of particle multiplicity are studied in dependence on the chemical potential but at fixed temperature and on the chemical potential but at fixed temperature. These are implem...
Institute of Scientific and Technical Information of China (English)
GENG Yi; SUN Xiaodan; CAI Qiang; SHI Yantao; LI Hengde
2006-01-01
Composite gel electrolytes containing several kinds of particles used as the quasi-solid-state electrolytes in dye-sensitized solar cells (DSSCs) were reported. Mesoporous particles (MCM-41) with unique structures composed of ordered nanochannels were served as a new kind of gelator for quasi-solid-state electrolytes. MCM-41, hydrophobic fumed silica Aerosil R972 and TiO2 nanopatricles P25 were dispersed into gel electrolytes respectively. The solar energy-to-electricity conversion efficiency of these cells is 4.65%, 6.85% and 5.05% respectively under 30 mW·cm-2 illumination. The preparation methods and the particles sizes exert an influence on the performance of corresponding solar cells. Owing to unique pore structures and high specific BET surface area, mesoporous silica MCM-41 was expected to have the potential to afford conducting nanochannels for redox couple diffusion.
Beyond the Quasi-Particle picture in Nuclear Matter calculations using Green's function techniques
Köhler, H S
2006-01-01
Widths of low-lying states in nuclei are of the order of 30 MeV. These large widths are a consequence of the strong interactions leading to a strongly correlated many body system at the typical densities of nuclear matter. Nevertheless "traditional" Brueckner calculations treat these states as quasiparticles i.e. with spectral functions of zero widths. The width is related to the imaginary part of the selfenergy and is included selfconsistently in an extension of the Brueckner theory using T-matrix and Green's function techniques. A more general formulation applicable also to non-equilibrium systems is contained in the Kadanoff-Baym (KB) equations while still maintaining the basic many-body techniques of Bruecknet theory. In the present work the two-time KB-equations are time-stepped along the imaginary time-axis to calculate the binding energy of nuclear matter as a function of density, including the spectral widths self-consistently. These zero temperature calculations are compared with quasi-particle calcu...
Glattli, D. C.; Roulleau, P.
2016-02-01
We study the Hanbury Brown and Twiss correlation of electronic quasi-particles injected in a quantum conductor using current noise correlations and we experimentally address the effect of finite temperature. By controlling the relative time of injection of two streams of electrons it is possible to probe the fermionic antibunching, performing the electron analog of the optical Hong Ou Mandel (HOM) experiment. The electrons are injected using voltage pulses with either sine-wave or Lorentzian shape. In the latter case, we propose a set of orthogonal wavefunctions, describing periodic trains of multiply charged electron pulses, which give a simple interpretation to the HOM shot noise. The effect of temperature is then discussed and experimentally investigated. We observe a perfect electron anti-bunching for a large range of temperature, showing that, as recently predicted, thermal mixing of the states does not affect anti-bunching properties, a feature qualitatively different from dephasing. For single charge Lorentzian pulses, we provide experimental evidence of the prediction that the HOM shot noise variation versus the emission time delay is remarkably independent of the temperature.
Kinetic structures of quasi-perpendicular shocks in global particle-in-cell simulations
Energy Technology Data Exchange (ETDEWEB)
Peng, Ivy Bo, E-mail: bopeng@kth.se; Markidis, Stefano; Laure, Erwin [KTH Royal Institute of Technology, Stockholm (Sweden); Johlander, Andreas; Vaivads, Andris; Khotyaintsev, Yuri [Swedish Institute of Space Physics, Uppsala (Sweden); Henri, Pierre [LPC2E-CNRS, Orléans (France); Lapenta, Giovanni [Centre for mathematical Plasma-Astrophysics, KU Leuven, Leuven (Belgium)
2015-09-15
We carried out global Particle-in-Cell simulations of the interaction between the solar wind and a magnetosphere to study the kinetic collisionless physics in super-critical quasi-perpendicular shocks. After an initial simulation transient, a collisionless bow shock forms as a result of the interaction of the solar wind and a planet magnetic dipole. The shock ramp has a thickness of approximately one ion skin depth and is followed by a trailing wave train in the shock downstream. At the downstream edge of the bow shock, whistler waves propagate along the magnetic field lines and the presence of electron cyclotron waves has been identified. A small part of the solar wind ion population is specularly reflected by the shock while a larger part is deflected and heated by the shock. Solar wind ions and electrons are heated in the perpendicular directions. Ions are accelerated in the perpendicular direction in the trailing wave train region. This work is an initial effort to study the electron and ion kinetic effects developed near the bow shock in a realistic magnetic field configuration.
Kinetic Structures of Quasi-Perpendicular Shocks in Global Particle-in-Cell Simulations
Peng, I. B.; Markidis, S.; Laure, E.; Johlander, A.; Vaivads, A.; Khotyaintsev, Y. V.; Pierre, H.; Lapenta, G.
2015-12-01
We carried out global Particle-in-Cell simulations of the interaction between the solar wind and a magnetosphere to study the kinetic collisionless physics in super-critical quasi-perpendicular shocks. After an initial simulation transient, a collisionless bow shock forms as a result of the interaction of the solar wind and a planet magnetic dipole. The shock ramp has a thickness of approximately one ion skin depth and is followed by a trailing wave train in the shock downstream. At the downstream edge of the bow shock, whistler waves propagate along the magnetic field lines and the presence of electron cyclotron waves has been identified. A small part of the solar wind ion population is specularly reflected by the shock while a larger part is deflected and heated by the shock. Solar wind ions and electrons are heated in the perpendicular directions. Ions are accelerated in the perpendicular direction in the trailing wave train region. This work is an initial effort to study the electron and ion kinetic effects developed near the bow shock in a realistic magnetic field configuration.
Vlad, M
2016-01-01
The quasi-coherent effects in two-dimensional incompressible turbulence are analyzed starting from the test particle trajectories. They can acquire coherent aspects when the stochastic potential has slow time variation and the motion is not strongly perturbed. The trajectories are, in these conditions, random sequences of large jumps and trapping or eddying events. Trapping determines quasi-coherent trajectory structures, which have a micro-confinement effect that is reflected in the transport coefficients. They determine non-Gaussian statistics and flows associated to an average velocity. Trajectory structures also influence the test modes on turbulent plasmas. Nonlinear damping and generation of zonal flow modes is found in drift turbulence in uniform magnetic field. The coupling of test particle and test mode studies permitted to evaluate the self-consistent evolution of the drift turbulence in an iterated approach. The results show an important nonlinear effect of ion diffusion, which can prevent the tran...
Directory of Open Access Journals (Sweden)
M.V. Tkach
2016-12-01
Full Text Available Using the Feynman-Pines diagram technique, the energy spectrum of localized quasi-particles interacting with polarization phonons is calculated and analyzed in the wide range of energies at the finite temperature of the system. It is established that the general model of the system, besides the bound states known from the simplified model with an additional condition for the operator of quasi-particles number, contains the new bound states even for the systems with weak coupling. The contribution of multi-phonon processes into the formation of renormalized spectrum of the system is analyzed. The reasons of the appearance, behaviour and disappearance of separate pairs of bound states depending on the coupling constant and temperature are revealed.
Energy Technology Data Exchange (ETDEWEB)
Schlottmann, P. [Department of Physics, Florida State University, MC 4350-309 Keene Building, Tallahassee, FL 32306 (United States)]. E-mail: schlottm@martech.fsu.edu
2004-12-31
The nesting of the Fermi surfaces of an electron pocket and a hole pocket separated by a wave vector Q and the interaction between electrons gives rise to spin- and charge-density waves. The order can gradually be suppressed by mismatching the nesting and a quantum critical point is obtained as the critical temperature tends to zero. We calculate the quasi-particle damping close to the quantum critical point and discuss its consequences on the resistivity and Hall effect.
Yu, Peicheng; Xu, Xinlu; Davidson, Asher; Tableman, Adam; Dalichaouch, Thamine; Li, Fei; Meyers, Michael D.; An, Weiming; Tsung, Frank S.; Decyk, Viktor K.; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo A.; Lu, Wei; Silva, Luis O.; Mori, Warren B.
2016-07-01
When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at βb c towards the laser, which can lead to a computational speedup of ∼ γb2 = (1 - βb2)-1. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited number of azimuthal harmonics, speedups are achieved by modeling three dimensional (3D) problems with the computational loads on the order of two dimensional r - z simulations. Here, we describe a method to combine the speedups from the Lorentz boosted frame and quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT solver in the quasi-3D geometry that significantly mitigates the Numerical Cerenkov Instability (NCI) which inevitably arises in a Lorentz boosted frame due to the unphysical coupling of Langmuir modes and EM modes of the relativistically drifting plasma in these simulations. In addition, based on the space-time distribution of the LWFA data in the lab and boosted frame, we propose to use a moving window to follow the drifting plasma, instead of following the laser driver as is done in the LWFA lab frame simulations, in order to further reduce the computational loads. We describe the details of how the NCI is mitigated for the quasi-3D geometry, the setups for simulations which combine the Lorentz boosted frame, quasi-3D geometry, and the use of a moving window, and compare the results from these simulations against their corresponding lab frame cases. Good agreement is obtained among these sample simulations, particularly when there is no self-trapping, which demonstrates it is possible to combine the Lorentz boosted frame and the quasi-3D algorithms when modeling LWFA. We also discuss the preliminary speedups achieved in these sample simulations.
Q-balls of Quasi-particles in a (2,0)-theory model of the Fractional Quantum Hall Effect
Ganor, Ori J; Moore, Nathan; Sun, Hao-Yu; Tan, H S; Torres-Chicon, Nesty R
2014-01-01
A toy model of the fractional quantum Hall effect appears as part of the low-energy description of the Coulomb branch of the $A_1$ (2,0)-theory formulated on $(S^1\\times R^2)/Z_k$, where the generator of $Z_k$ acts as a combination of translation on $S^1$ and rotation by $2\\pi/k$ on $R^2$. At low-energy the configuration is described in terms of a 4+1D Super-Yang-Mills theory on a cone ($R^2/Z_k$) with additional 2+1D degrees of freedom at the tip of the cone that include fractionally charged particles. These fractionally charged quasi-particles are BPS strings of the (2,0)-theory wrapped on short cycles. We analyze the large $k$ limit, where a smooth cigar-geometry provides an alternative description. In this framework a W-boson can be modeled as a bound state of $k$ quasi-particles. The W-boson becomes a Q-ball, and it can be described as a soliton solution of Bogomolnyi monopole equations on a certain auxiliary curved space. We show that axisymmetric solutions of these equations correspond to singular maps...
Institute of Scientific and Technical Information of China (English)
赵力; 李建新; 龚昌德; 赵柏儒
2002-01-01
In a self-consistent mean-field treatment of the two-dimensional t - t＇ - J model, we theoretically examine thecoupling of in-plane quasi-particles to the antiferromagnetic spin fluctuations in high-Tc superconductors, whichrenormalizes the fermionic self-energy. We reproduce the characteristic peak,lip-hump structure observed notonly in angle-resolved photoemission spectroscopy, but also in superconductor-insulator-normal metal junctionsand scanning tunnelling microscopy experiments. We consider the evolution of this structure with doping. Itis shown that this kind of coupling can account for many anomalous properties of high-Tc superconductors insuperconducting states.
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
We investigate the energy spectrum of ground state and quasi-particle excitation spectrum of hard-core bosons, which behave very much like spinless noninteracting fermions, in optical lattices by means of the perturbation expansion and Bogoliubov approach. The results show that the energy spectrum has a single band structure, and the energy is lower near zero momentum; the excitation spectrum gives corresponding energy gap, and the system is in Mott-insulating state at Tonks limit. The analytic result of energy spectrum is in good agreement with that calculated in terms of Green's function at strong correlation limit.
Contact forces between a particle and a wet wall at both quasi-static and dynamic state
Directory of Open Access Journals (Sweden)
Zhang Huang
2017-01-01
Full Text Available The contact regime of particle-wall is investigated by the atomic force microscope (AFM and theoretical models. First, AFM is used to measure the cohesive force between a micron-sized grain and a glass plate at quasi-static state under various humidity. It is found out that the cohesive force starts to grow slowly and suddenly increase rapidly beyond a critical Relative Humidity (RH. Second, mathematical models of contacting forces are presented to depict the dynamic process that a particle impacts on a wet wall. Then the energy loss of a falling grain is calculated in comparison with the models and the experimental data from the previous references. The simulation results show that the force models presented here are adaptive for both low and high viscosity fluid films with different thickness.
Radiation of Relativistic Particles in a Quasi-Homogeneous Magnetic Field
Epp, V
2016-01-01
Spectrum of radiation of a relativistic particle moving in a nonhomogeneous magnetic field is considered. The spectrum depends on the pitch-angle $\\alpha$ between the velocity direction and a line tangent to the field line. In case of very small $\\alpha$ the particle generates so-called curvature radiation, in an intermediate case undulator-kind radiation is produced. In this paper we present the calculations of radiation properties in a case when both curvature and undulator radiation is observed.
Detection of small metal particles by a quasi-optical system at sub-millimeter wavelength
Kitahara, Yasuyuki; Domier, C. W.; Ikeda, Makoto; Pham, Anh-Vu; Luhmann, Neville C.
2016-04-01
Inspection of alien metal particles in electronic materials such as glass fibers and resins is a critical issue to control the quality and guarantee the safety of products. In this paper, we present a new detection technique using sub-millimeter wave for films as electric materials in product lines. The advantage of using sub-millimeter wave frequency is that it is easy to distinguish conductive particles from a nonconductive material such as plastic films. Scattering of a submillimeter wave by a metal particle is used as the detection principle. By simulation, it is observed that the scattering pattern varies intricately as the diameter varies from 10 to 700 μm at 300 GHz. The demonstration system is composed of a Keysight performance network analyzer (N5247A PNA-X) with 150-330 GHz VDI extension modules, transmitting and receiving antennas, and focusing dielectric lens. An output signal is radiated via an antenna and focused onto a metal particle on a film. The wave scattered by the metal particle is detected by an identical antenna through a lens. The signal scattered from a metal particle is evaluated from the insertion loss between antennas (S21). The result shows that a particle of diameter 300 μm is detectable at 150-330 GHz through S21 in the experimental system that we prepared. Peaks calculated in simulation were detected in experimental data as well as in the curves of the particle diameter versus S21. It was shown that using this peak frequency could improve S21 level without higher frequency.
Gruca, Marta; Division of Complex Fluids Team
2014-11-01
We investigate dynamics of many particles settling under gravity in a viscous fluid within the Stokes flow regime. We consider several families of regular initial configurations of a large number of point-particles which lead to periodic and quasi-periodic motions of the particles. We vary the relative distance between particles and observe how does it affect the dynamics. We observe the oscillations under some out-of-phase rearrangements of the particles. We also see a large influence of initial conditions on the system stability. By perturbating the regular configurations we obtain the dynamics corresponding to the dynamics of drop of suspension. We also explore the dynamics of such system in porous media where analogous quasi-periodic motions have been found.
Pan, Chong; Wang, Hongping; Wang, Jinjun
2013-05-01
This work mainly deals with the proper orthogonal decomposition (POD) time coefficient method used for extracting phase information from quasi-periodic flow. The mathematical equivalence between this method and the traditional cross-correlation method is firstly proved. A two-dimensional circular cylinder wake flow measured by time-resolved particle image velocimetry within a range of Reynolds numbers is then used to evaluate the reliability of this method. The effect of both the sampling rate and Reynolds number on the identification accuracy is finally discussed. It is found that the POD time coefficient method provides a convenient alternative for phase identification, whose feasibility in low-sampling-rate measurement has additional advantages for experimentalists.
Tursunov, Arman; Kološ, Martin
2016-01-01
We study motion of charged particles in the field of a rotating black hole immersed into an external asymptotically uniform magnetic field, focusing on the epicyclic quasi-circular orbits near the equatorial plane. Separating the circular orbits into four qualitatively different classes according to the sign of the canonical angular momentum of the motion and the orientation of the Lorentz force, we analyse the circular orbits using the so called force formalism. We find the analytical solutions for the radial profiles of velocity, specific angular momentum and specific energy of the circular orbits in dependence on the black hole dimensionless spin and the magnetic field strength. The innermost stable circular orbits are determined for all four classes of the circular orbits. The stable circular orbits with outward oriented Lorentz force can extend to radii lower than the radius of the corresponding photon circular geodesic. We calculate the frequencies of the harmonic oscillatory motion of the charged parti...
Nagashima, Shigeo; Takahashi, Masaharu; Kobayashi, Tominari; Tanggis; Nishizawa, Tsutomu; Nishiyama, Takashi; Primadharsini, Putu Prathiwi; Okamoto, Hiroaki
2017-09-06
Our previous studies demonstrated that membrane-associated hepatitis E virus (HEV) particles-now considered "quasi-enveloped particles"-are present in the multivesicular body with intraluminal vesicles (exosomes) in infected cells, and that the release of HEV virions is related to the exosomal pathway. In this study, we characterized exosomes purified from culture supernatant of HEV-infected PLC/PRF/5 cells. Purified CD63-, CD9-, or CD81-positive exosomes derived from the culture supernatant of HEV-infected cells that had been cultivated in serum-free medium were found to contain HEV RNA and the viral capsid (ORF2) and ORF3 proteins, as determined by a RT-PCR and Western blotting, respectively. Furthermore, immunoelectron microscopy, with or without prior detergent and protease treatment, revealed the presence of virus-like particles in the exosome fraction. These particles were 39.6 ± 1.0 nm in diameter, and were covered with a lipid membrane. After treatment with detergent and protease, the diameter of these virus-like particles was 26.9 ± 0.9 nm, and the treated particles became accessible with an anti-HEV ORF2 monoclonal antibody (mAb). The HEV particles in the exosome fraction were capable of infecting native PLC/PRF/5 cells, but were not neutralized by an anti-HEV ORF2 mAb, which can efficiently neutralize the non-enveloped HEV particles in cell culture. These results indicate that the membrane-wrapped HEV particles released by the exosomal pathway are co-purified with the exosomes in the exosome fraction, and suggest that the capsids of HEV particles are individually covered by lipid membranes resembling those of exosomes, similarly to enveloped viruses.IMPORTANCE Hepatitis E, caused by HEV, is an important infectious disease that is spreading worldwide. HEV infection can cause acute or fulminant hepatitis and can become chronic in immunocompromised hosts, including patients after organ transplantation. The HEV particles present in feces and bile are non
Isospin and particle representations for quasi-bound state of kaonic clusters
Filikhin, Igor; Kezerashvili, Roman; Vlahovic, Branislav
2017-01-01
In the framework of the method of the Faddeev equations in configuration space, the NNK (I = 0) (and KK) kaonic cluster system including two identical particles is considered. We use the formalism of isospin and particle representations to describe the systems. The treatment of I = 1 and I = 0 isospin KN channels is discussed. The presence of the Coulomb force in ppK- channel violates the isospin symmetry of the NNK (I = 0) system. According to the particle representation, NNK is a two-level system of coupled ppK- and ppnl channels with and without the Coulomb energy, respectively. The results of calculations for the bound states with the phenomenological and chiral motivated KN potentials are given for different representations. In particular, new single channel calculations for the ppK- (and K-K- p) cluster are presented. It is shown that the exchange of identical particles plays an important role in the formation of a bound state of the systems. The relation of the exchange and the three-body mass rearrangement effects is discussed. This work is supported by the National Science Foundation grant Supplement to the NSF grant HRD-1345219 and NASA (NNX09AV07A).
Park, Jaehong; Workman, Jared C; Blackman, Eric G
2012-01-01
Low Mach number, high beta fast mode shocks can occur in the magnetic reconnection outflows of solar flares. These shocks, which occur above flare loop tops, may provide the electron energization responsible for some of the observed hard X-rays and contemporaneous radio emission. Here we present new 2D particle-in-cell simulations of low Mach number/high beta quasi-perpendicular shocks. The simulations show that electrons above a certain energy threshold experience shock-drift-acceleration. The transition energy between the thermal and non-thermal spectrum and the spectral index from the simulations are consistent with some of the X-ray spectra from RHESSI in the energy regime, $E\\lesssim 40\\sim 100$ keV. Plasma instabilities associated with the shock structure such as the modified-two-stream and the electron whistler/mirror instabilities are examined and compared with the numerical solutions of the kinetic dispersion relations.
A spectral, quasi-cylindrical and dispersion-free Particle-In-Cell algorithm
Lehe, Remi; Andriyash, Igor A; Godfrey, Brendan B; Vay, Jean-Luc
2015-01-01
We propose a spectral Particle-In-Cell (PIC) algorithm that is based on the combination of a Hankel transform and a Fourier transform. For physical problems that have close-to-cylindrical symmetry, this algorithm can be much faster than full 3D PIC algorithms. In addition, unlike standard finite-difference PIC codes, the proposed algorithm is free of numerical dispersion. This algorithm is benchmarked in several situations that are of interest for laser-plasma interactions. These benchmarks show that it avoids a number of numerical artifacts, that would otherwise affect the physics in a standard PIC algorithm - including the zero-order numerical Cherenkov effect.
Single Particle Dynamics in a Quasi-Integrable Nonlinear Accelerator Lattice
Antipov, Sergey A; Valishev, Alexander
2016-01-01
Fermilab is constructing the Integrable Optics Test Accelerator (IOTA) as the centerpiece of the Accelerator R&D Program towards high-intensity circular machines. One of the factors limiting the beam intensity in present circular accelerators is collective instabilities, which can be suppressed by a spread of betatron frequencies (tunes) through the Landau damping mechanism or by an external damper, if the instability is slow enough. The spread is usually created by octupole magnets, which introduce the tune dependence on the amplitude and, in some cases, by a chromatic spread (tune dependence on particle's momentum). The introduction of octupoles usually lead to a resonant behavior and a reduction of the dynamic aperture. One of the goals of the IOTA research program is to achieve a high betatron tune spread, while retaining a large dynamic aperture using conventional octupole magnets in a special but realistic accelerator configuration. In this report, we present results of computer simulations of an el...
Baryshevsky, Vladimir
2016-01-01
Until recently, the interaction of electromagnetic waves with crystals built from parallel metallic wires (wire media) was analyzed in the approximation of isotropic scattering of the electromagnetic wave by a single wire. However, if the wires are thick (kR~1), electromagnetic wave scattering by a wire is anisotropic, i.e., the scattering amplitude depends on the scattering angle. In this work, we derive the equations that describe diffraction of electromagnetic waves and spontaneous emission of charged particles in wire media, and take into account the angular dependence of scattering amplitude. Numerical solutions of these equations show that the radiation intensity increases as the wire radius is increased and achieves its maximal value in the range kR~1. The case when the condition kR~1 is fulfilled in the THz frequency range is considered in detail. The calculations show that the instantaneous power of Cherenkov and parametric (quasi-Cherenkov) radiations from electron bunches in the crystal can be tens...
Glattli, D. C.; Roulleau, P.
2016-08-01
We study the Hanbury Brown and Twiss correlation of electronic quasi-particles injected in a quantum conductor using current noise correlations and we experimentally address the effect of finite temperature. By controlling the relative time of injection of two streams of electrons it is possible to probe the fermionic antibunching, performing the electron analog of the optical Hong Ou Mandel (HOM) experiment. The electrons are injected using voltage pulses with either sine-wave or Lorentzian shape. In the latter case, we propose a set of orthogonal wavefunctions, describing periodic trains of multiply charged electron pulses, which give a simple interpretation to the HOM shot noise. The effect of temperature is then discussed and experimentally investigated. We observe a perfect electron anti-bunching for a large range of temperature, showing that, as recently predicted, thermal mixing of the states does not affect anti-bunching properties, a feature qualitatively different from dephasing. For single charge Lorentzian pulses, we provide experimental evidence of the prediction that the HOM shot noise variation versus the emission time delay is remarkably independent of the temperature.
GPU-based quasi-real-time Track Recognition in Imaging Devices: from raw Data to Particle Tracks
Bozza, Cristiano; De Sio, Chiara; Stellacci, Simona Maria
2015-01-01
Nuclear emulsions as tracking devices have been used by recent experiments thanks to fast automatic microscopes for emulsion readout. Automatic systems are evolving towards GPU-based solutions. Real-time imaging is needed to drive the motion of the microscope axes and 3D track recognition occurs quasi-online in local GPU clusters. The algorithms implemented in the Quick Scanning System are sketched. Most of them are very general and might turn out useful for other detector
Osorio-Guillén, J. M.; Espinosa-García, W. F.; Moyses Araujo, C.
2015-09-01
First-principles quasi-particle theory has been employed to assess catalytic power of graphitic carbon nitride, g-C3N4, for solar fuel production. A comparative study between g-h-triazine and g-h-heptazine has been carried out taking also into account van der Waals dispersive forces. The band edge potentials have been calculated using a recently developed approach where quasi-particle effects are taken into account through the GW approximation. First, it was found that the description of ground state properties such as cohesive and surface formation energies requires the proper treatment of dispersive interaction. Furthermore, through the analysis of calculated band-edge potentials, it is shown that g-h-triazine has high reductive power reaching the potential to reduce CO2 to formic acid, coplanar g-h-heptazine displays the highest thermodynamics force toward H2O/O2 oxidation reaction, and corrugated g-h-heptazine exhibits a good capacity for both reactions. This rigorous theoretical study shows a route to further improve the catalytic performance of g-C3N4.
Daqing, Yuan; Ping, Fan; Yongnan, Zheng; Yi, Zuo; Dongmei, Zhou; Qiaoli, Zhang; Xiaoguang, Wu; Guangsheng, Li; Lihua, Zhu; Guoji, Xu; Qiwen, Fan; Xizhen, Zhang; Matsuta, K.; Fukuda, M.; Mihara, M.; Minamisono, T.; Shengyun, Zhu
2010-06-01
Dependence of quasi-particle alignment on proton and neutron numbers has been studied in A = 80 mass region through g-factor measurements by using TMF-IMPAD. The experimental results show that for the nuclides 84Zr, 85Zr and 86Zr with Z = 40 the proton alignment is followed by the neutron alignment in 84Zr and 85Zr, while the neutron alignment is followed by the proton alignment in 86Zr, and for the nuclides 82Sr, 83Y, 84Zr and 85Nb with N = 44 the proton aligns only in 82Sr, the proton alignment occurs first that is followed by the neutron alignment in 83Y and 84Zr and the neutron alignment is followed by the proton alignment in 85Nb. Proton and/or neutron alignments lead to different patterns of the g-factor variation with spin.
Kortenkamp, Stephen J.
2016-10-01
We use numerical integrations to model the orbital evolution of IDPs decaying from the asteroid belt into the inner solar system under the influence of radiation pressure, Poynting-Roberston light drag, and solar wind drag. In our models the ratio of radiation pressure to solar gravity ranges from 0.0025 up to 0.02, corresponding to IDP diameters ranging from about 200 microns down to about 25 microns, respectively. In this size range nearly 100% of IDPs become temporarily trapped in mean-motion resonances just outside Earth's orbit. While trapped in these outer resonances the orbital eccentricities of IDPs significantly increases. This causes most IDPs to eventually escape the resonances, allowing their orbits to continue decaying inwards past 1 AU. We've shown previously (Kortenkamp, Icarus 226, 1550-1558, 2013) that significant fractions of IDPs in this size range can subsequently become trapped in Earth's co-orbital horseshoe and quasi-satellite resonance regions, with semi-major axes just inside of 1 AU. Here, we present new results on the long-term effects of Earth's varying orbital eccentricity and inclination on the trapping and evolution of these co-orbital IDPs.
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
Polymer bonded explosives (PBXs) are highly particle-filled composite materials.This paper experimentally studies the tensile deformation and fracture behavior of a PBX simulation by using the semi-circular bending (SCB) test.The deformation and fracture process of a pre-notched SCB sample with a random speckle pattern is recorded by a charge coupled device camera.The displacement and strain fields on the observed surface during the loading process are obtained by using the digital image correlation method....
Continuous quantum mechanics of single particles in closed and quasi-closed systems: Pt. 1 and 2
Energy Technology Data Exchange (ETDEWEB)
Brieger, M. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Stuttgart (Germany). Inst. fuer Technische Physik
2004-07-01
The established statistical interpretation of quantum mechanics never envisioned our today's ability to handle and investigate single particles in trap devices. After scrutinizing the development of quantum mechanics, we point out that Schroedinger's equation establishes an energy representation, which obtains the energy eigenvalues as extrema of the energy curve or on the energy hypersurface, respectively. We also strongly emphasize its never exhausted capability of accounting in classical terms and full detail for the dynamics of single particles in closed systems. This is demonstrated for several familiar examples. They show that the eigensolutions to Schroedinger's equation must not blindly be identified with physically stationary states. The gained insight into the true dynamics allows to describe, without involving QED, the time evolution of a complete spontaneous transition as being driven by unbalanced internal dynamics. This mechanism relies on the fact that perfect balances are only possible in the exact extrema of the total energy and that any deviation, which is characterized by nonstationary states, makes multipole moments oscillate and emit electromagnetic radiation. (orig.)
Covariant Kaon Dynamics and Properties of Quasi-particle Models%K介子协变动力学及其准粒子模型的性质
Institute of Scientific and Technical Information of China (English)
王艳艳; 朱玉兰; 邢永忠; 郑玉明
2011-01-01
简要综述了中高能重离子碰撞中K介子的产生及研究进展。重点介绍了K介子协变动力学模型,并在此框架内分析了中高能重离子碰撞中K＋介子以及与其伴随产生的Λ超子的集体流特征。结果表明：协变动力学模型能够很好地给出K＋介子和Λ超子的微分直接流。相对而言,软势给出的集体流与实验值符合更好。同时,通过对不同输运模型中K介子准粒子模型的基本属性进行对比分析,明确了协变动力学模型中K介子准粒子模型的质量及能量随核物质密度的变化特征,以及周围核子的运动对于K介子基本属性的影响。%In the present paper,we briefly review the progress in the study of kaon production in heavy-ion collisions at intermediate and high energies and introduce the covariant kaon dynamics model.The collective flows of positively charged kaon and the lambda hyperon associated produced with kaon are studied in the framework of the dynamics.It shows that the directed differential flow of K＋ meson and Λ hyperon can be reasonably reproduced in the covariant kaon dynamics model.The calculated results with soft equation of nuclear matter are in better agrement with experimental data.Meawhile,a detailed comparison of the properites of different quasi-particle models in various transport model and the influence of nucleon＇s movement on the effective mass and energy of the quasi-particle in the covariant kaon dynamics model are discussed.
Bian, Nicolas H; Ratcliffe, Heather
2015-01-01
Of particular interest for radio and hard X-ray diagnostics of accelerated electrons during solar flares is the understanding of the basic non-linear mechanisms regulating the relaxation of electron beams propagating in turbulent plasmas. In this work, it is shown that in addition to scattering of beam electrons, scattering of the beam-generated Langmuir waves via for instance mode-coupling, can also result in broadening of the wave-particle resonance. We obtain a resonance-broadened version of weak-turbulence theory with mode-coupling to ion-sound modes. Resonance broadening is presented here as a unified framework which can quantitatively account for the reduction and possible suppression of the beam instability due to background scattering of the beam electrons themselves or due to scattering of the beam-generated Langmuir waves in fluctuating plasmas. Resonance broadening being essentially equivalent to smoothing of the electron phase-space distribution, it is used to construct an intuitive physical pictu...
Jackman, C. M.; Thomsen, M. F.; Mitchell, D. G.; Sergis, N.; Arridge, C. S.; Felici, M.; Badman, S. V.; Paranicas, C.; Jia, X.; Hospodarksy, G. B.; Andriopoulou, M.; Khurana, K. K.; Smith, A. W.; Dougherty, M. K.
2015-05-01
We present a case study of an event from 20 August (day 232) of 2006, when the Cassini spacecraft was sampling the region near 32 RS and 22 h LT in Saturn's magnetotail. Cassini observed a strong northward-to-southward turning of the magnetic field, which is interpreted as the signature of dipolarization of the field as seen by the spacecraft planetward of the reconnection X line. This event was accompanied by very rapid (up to ~1500 km s-1) thermal plasma flow toward the planet. At energies above 28 keV, energetic hydrogen and oxygen ion flow bursts were observed to stream planetward from a reconnection site downtail of the spacecraft. Meanwhile, a strong field-aligned beam of energetic hydrogen was also observed to stream tailward, likely from an ionospheric source. Saturn kilometric radiation emissions were stimulated shortly after the observation of the dipolarization. We discuss the field, plasma, energetic particle, and radio observations in the context of the impact this reconnection event had on global magnetospheric dynamics.
Savoini, P.; Lembege, B.
2015-12-01
The ion foreshock located upstream of the Earth's shock wave is populated with ions having interacted with the shock, and then, reflected back with an high energy gain. Spacecrafts have clearly established the existence of two distinct populations in the quasi-perpendicular shock region (i.e. for 45° ≤ ΘBn ≤ 90°, where ΘBn is the angle between the shock normal and the upstream magnetic field) : (i) field-aligned ion beams or « FAB » characterized by a gyrotropic distribution, and (ii) gyro-phase bunched ions or « GPB » characterized by a NON gyrotropic distribution. One of the important unresolved problem is the exact origin of the particles contributing to these two populations. To our knowledge, it was the first time that full-particle simulations have been performed including self-consistently the shock front curvature and nonstationarity, and the time-of-flight effects. Our analysis evidences that these two backstreaming populations may be reflected by the front itself and can be differentiated both in terms of interaction time and trajectory within the shock front. In particular, simulations evidence that "GPB" population is characterized by a short interaction time (ΔTinter = 1 to 2 τci) while the "FAB" population corresponds to a much larger time range (from 1 τci to 10 τci), where tci is the upstream ion gyroperiod. Present individual ion trajectories evidence that "FAB" population shows a strong perpendicular drift at the shock front (i.e. strong dependence of the pitch angle to the perpendicular velocity) whereas the "GPB" population shows no perpendicular drift (i.e. its pitch angle is mainly driven by the parallel velocity). Such differences explain why the "FAB" population loses their gyro-phase coherency and become gyrotropic which is not the case for the "GPB". This important result was not expected and greatly simplifies the question of their origin.
Fakis, Demetrios; Kalvouridis, Tilemahos
2017-09-01
The regular polygon problem of (N+1) bodies deals with the dynamics of a small body, natural or artificial, in the force field of N big bodies, the ν=N-1 of which have equal masses and form an imaginary regular ν -gon, while the Nth body with a different mass is located at the center of mass of the system. In this work, instead of considering Newtonian potentials and forces, we assume that the big bodies create quasi-homogeneous potentials, in the sense that we insert to the inverse square Newtonian law of gravitation an inverse cube corrective term, aiming to approximate various phenomena due to their shape or to the radiation emitting from the primaries. Based on this new consideration, we apply a general methodology in order to investigate by means of the zero-velocity surfaces, the regions where 3D motions of the small body are allowed, their evolutions and parametric variations, their topological bifurcations, as well as the existing trapping domains of the particle. Here we note that this process is definitely a fundamental step of great importance in the study of many dynamical systems characterized by a Jacobian-type integral of motion in the long way of searching for solutions of any kind.
Directory of Open Access Journals (Sweden)
Décio Krause
2002-11-01
Full Text Available Quasi-set theory was developed to deal with collections of indistinguishable objects. In standard mathematics, there are no such kind of entities, for indistinguishability (agreement with respect to all properties entails numerical identity. The main motivation underlying such a theory is of course quantum physics, for collections of indistinguishable (’identical’ in the physicists’ jargon particles cannot be regarded as ’sets’ of standard set theories, which are collections of distinguishable objects. In this paper, a rationale for the development of such a theory is presented, motivated by Heinz Post’s claim that indistinguishability ofquantum entities should be attributed ’right at the start’.
Energy Technology Data Exchange (ETDEWEB)
Osorio-Guillén, J. M., E-mail: mario.osorio@udea.edu.co [Instituto de Física, Universidad de Antioquia UdeA, Calle 70 No 52-21, Medellín (Colombia); Espinosa-García, W. F. [Instituto de Física, Universidad de Antioquia UdeA, Calle 70 No 52-21, Medellín (Colombia); Grupo de Investigación en Modelamiento y Simulación Computacional, Facultad de Ingenierías, Universidad de San Buenaventura Seccional Medellín, Carrera 56C No 51-110, Medellín (Colombia); Moyses Araujo, C., E-mail: moyses.araujo@physics.uu.se [Materials Theory Division, Department of Physics and Astronomy, Uppsala University, P.O. Box 516, S75120 Uppsala (Sweden)
2015-09-07
First-principles quasi-particle theory has been employed to assess catalytic power of graphitic carbon nitride, g-C{sub 3}N{sub 4}, for solar fuel production. A comparative study between g-h-triazine and g-h-heptazine has been carried out taking also into account van der Waals dispersive forces. The band edge potentials have been calculated using a recently developed approach where quasi-particle effects are taken into account through the GW approximation. First, it was found that the description of ground state properties such as cohesive and surface formation energies requires the proper treatment of dispersive interaction. Furthermore, through the analysis of calculated band-edge potentials, it is shown that g-h-triazine has high reductive power reaching the potential to reduce CO{sub 2} to formic acid, coplanar g-h-heptazine displays the highest thermodynamics force toward H{sub 2}O/O{sub 2} oxidation reaction, and corrugated g-h-heptazine exhibits a good capacity for both reactions. This rigorous theoretical study shows a route to further improve the catalytic performance of g-C{sub 3}N{sub 4}.
Butler, Keith T.; McKechnie, Scott; Azarhoosh, Pooya; van Schilfgaarde, Mark; Scanlon, David O.; Walsh, Aron
2016-03-01
The ternary V-VI-VII chalcohalides consist of one cation and two anions. Trivalent antimony—with a distinctive 5s2 electronic configuration—can be combined with a chalcogen (e.g., S or Se) and halide (e.g., Br or I) to produce photoactive ferroelectric semiconductors with similarities to the Pb halide perovskites. We report—from relativistic quasi-particle self-consistent GW theory—that these materials have a multi-valley electronic structure with several electron and hole basins close to the band extrema. We predict ionisation potentials of 5.3-5.8 eV from first-principles for the three materials, and assess electrical contacts that will be suitable for achieving photovoltaic action from these unconventional compounds.
Quasi-exactly solvable models derived from the quasi-Gaudin algebra
Energy Technology Data Exchange (ETDEWEB)
Lee, Yuan-Harng; Links, Jon; Zhang Yaozhong, E-mail: jrl@uq.edu.au [School of Mathematics and Physics, The University of Queensland, Brisbane, Qld 4072 (Australia)
2011-12-02
The quasi-Gaudin algebra was introduced to construct integrable systems which are only quasi-exactly solvable. Using a suitable representation of the quasi-Gaudin algebra, we obtain a class of bosonic models which exhibit this curious property. These models have the notable feature that they do not preserve U(1) symmetry, which is typically associated with a non-conservation of particle number. An exact solution for the eigenvalues within the quasi-exactly solvable sector is obtained via the algebraic Bethe ansatz formalism. (fast track communication)
Quasi-specular reflection from particulate media
Penttilä, Antti
2013-01-01
Specular reflection is known to play an important role in many fields of scattering applications, e.g., in remote sensing, computer graphics, optimization of visual appearance of industrial products. Usually it can be assumed that the object has a solid surface and that the properties of the surface will dictate the behavior of the specular component. In this study I will show that media consisting of wavelength-sized particles can also have a quasi-specular reflection in cases where there is ordered structure in the media. I will also show that the quasi-specular reflection in particulate media is more than just a surface effect, and planar particle arrangement below the very surface can give arise to quasi-specular reflection. This study shows that the quasi-specular reflection may contribute in some cases in the backscattering direction, together with coherent backscattering and shadow-hiding effects.
Energy Technology Data Exchange (ETDEWEB)
Hanson, P.
1982-10-01
The two and quasi-two body final states ..sigma../sup +/K/sup +/, ..sigma../sup +/K* (892)/sup +/, ..sigma..*(1385)/sup +/K/sup +/, ..sigma..(1385)/sup +/K*(892)/sup +/ produced by neutral strangeness exchange in ..pi../sup +/p interactions are studied using our own 1-3 GeV/c data, comprising the 14 incident momenta of a two million picture bubble chamber experiment, in combination with the world data on the same and related channels. Because low energy resonance formation is not strongly coupled to the ..sigma..,..sigma..* production channels, at very modest incident momenta their dominant features are seen to be understandable in terms of high energy hypercharge exchange phenomenology. We find that Regge models fitted to data in the 10 to 20 GeV/c range adequately describe the ..sigma.. and ..sigma..* channels down to within a few hundred MeV/c of threshold and out to large center of mass scattering angles, and that over the range of the available world data weak exchange degeneracy expectations for these reactions are at least qualitatively successful. We observe that the SU(2), SU(3) flavor symmetries successfully describe these hypercharge exchange processes and relate them to charge exchange via sum rules and equalities expressing flavor independence of the strong interaction; in particular, we derive and test on the available world data a mass broken SU(3) sum rule for ..pi../sup +/p ..-->.. K/sup +/..sigma../sup +/, ..pi../sup -/p ..-->.. K/sup 0/..lambda.., K/sup -/p ..-->.. anti K/sup 0/n and test over a wider range of momenta than before an earlier expression relating ..sigma..* and ..delta.. production. We also find at least qualitative agreement between quark model predictions for forward hypercharge exchange and the data, and we find that 90/sup 0/ hypercharge exchange cross sections also conform to the expectations of the quark constituent picture for hadrons.
Energy Technology Data Exchange (ETDEWEB)
Kotaki, T.; Uraguchi, Y.; Makihara, T.; Suenaga, M.; Sueyoshi, T.; Fujiyoshi, T., E-mail: fuji@cs.kumamoto-u.ac.jp; Mitugi, F.; Ikegami, T.
2015-11-15
Highlights: • BSO nanoparticles which grown at higher temperature have larger diameter. • BSO nanoparticles which have large diameter make a broad peak of J{sub c} around B || c. • BSO/YBCO film which grown at 770 °C shows the improvement of J{sub c} at high temperature. • BHO doped YBCO multilayered film does not show the improvement of J{sub c.} - Abstract: In order to investigate the influence of diameter and spatial distribution of three-dimensional (3D) pinning centers on critical current density J{sub c}, BMO (BaSnO{sub 3} (BSO) or BaHfO{sub 3} (BHO)) doped YBa{sub 2}Cu{sub 3}O{sub y} (YBCO) thin films were fabricated by a quasi-multilayering process using a pulsed laser deposition method. The prepared films are referred as BMO(m,n)T{sub s}, where m and n denotes the number of laser pulse on the BMO target and the total number of BMO/YBCO bilayers, respectively and T{sub s} is the growth temperature. BSO(1,100)750 and BSO(1,100)770 show the improvement of J{sub c} in comparison with the pure YBCO sample in wide range of magnetic field directions at 65 K. However, at 77.3 K, improvement of J{sub c} was seen in only BSO(1,100)770. The BSO nano-particles within BSO(1,100)770 are considered to have larger diameter, so that BSO nano-particles can immobilize the flux lines in the high temperature region. In addition, BSO(1,100)770 shows the high peak of J{sub c} centered at θ = 0° in the angular dependence of J{sub c}. On the other hand, the J{sub c} of BHO(1,100)770 falls below that of pure YBCO samples in all magnetic field orientation. In addition, at 65 K, there is no peak of J{sub c} at any angles except for θ = 90°. These results indicates that the diameter of BHO nano-particles in BHO(1,100)770 might be much smaller than that of BSO nano-particle and BHO nanoparticles cannot work as effective pinning center.
Sawamura, Akitaka; Otsuka, Jun; Kato, Takashi; Kotani, Takao
2017-06-01
We report the determination of parameters for the nearest-neighbor sp3s* tight-binding (TB) model for GaP, GaAs, GaSb, InP, InAs, and InSb at 0, 77, and 300 K based on the hybrid quasi-particle self-consistent GW (QSGW) calculation and their application to a type II (InAs)/(GaSb) superlattice. The effects of finite temperature have been incorporated empirically by adjusting the parameter for blending the exchange-correlation terms of the pure QSGW method and local density approximation, in addition to the usage of experimental lattice parameters. As expected, the TB band gap shrinks with temperature and asymptotically with superlattice period when it is large. In addition, a bell curve in the band gap in the case of small superlattice period and slight and remarkable anisotropy in effective masses of electron and hole, both predicted by the hybrid QSGW method, respectively, are reproduced.
Institute of Scientific and Technical Information of China (English)
Guijun YANG; Lu LIN; Runchu ZHANG
2007-01-01
Quasi-regression, motivated by the problems arising in the computer experiments, focuses mainly on speeding up evaluation. However, its theoretical properties are unexplored systemically. This paper shows that quasi-regression is unbiased, strong convergent and asymptotic normal for parameter estimations but it is biased for the fitting of curve. Furthermore, a new method called unbiased quasi-regression is proposed. In addition to retaining the above asymptotic behaviors of parameter estimations, unbiased quasi-regression is unbiased for the fitting of curve.
Chiral bands for quasi-proton and quasi-neutron coupling with a triaxial rotor
Zhang, S Q; Qi, B; Wang, S Y
2007-01-01
A particle rotor model (PRM) with a quasi-proton and a quasi-neutron coupled with a triaxial rotor is developed and applied to study chiral doublet bands with configurations of a $h_{11/2}$ proton and a $h_{11/2}$ quasi-neutron. With pairing treated by the BCS approximation, the present quasi-particle PRM is aimed at simulating one proton and many neutron holes coupled with a triaxial rotor. After a detailed analysis of the angular momentum orientations, energy separation between the partner bands, and behavior of electromagnetic transitions, for the first time we find aplanar rotation or equivalently chiral geometry beyond the usual one proton and one neutron hole coupled with a triaxial rotor.
Error in Monte Carlo, quasi-error in Quasi-Monte Carlo
Kleiss, R. H. P.; Lazopoulos, A.
2006-01-01
While the Quasi-Monte Carlo method of numerical integration achieves smaller integration error than standard Monte Carlo, its use in particle physics phenomenology has been hindered by the abscence of a reliable way to estimate that error. The standard Monte Carlo error estimator relies on the assumption that the points are generated independently of each other and, therefore, fails to account for the error improvement advertised by the Quasi-Monte Carlo method. We advocate the construction o...
Quasi-Maxwell interpretation of the spin-curvature coupling
Natario, J
2007-01-01
We write the Mathisson-Papapetrou equations of motion for a spinning particle in a stationary spacetime using the quasi-Maxwell formalism and give an interpretation of the coupling between spin and curvature.
Generalized quasi variational inequalities
Energy Technology Data Exchange (ETDEWEB)
Noor, M.A. [King Saud Univ., Riyadh (Saudi Arabia)
1996-12-31
In this paper, we establish the equivalence between the generalized quasi variational inequalities and the generalized implicit Wiener-Hopf equations using essentially the projection technique. This equivalence is used to suggest and analyze a number of new iterative algorithms for solving generalized quasi variational inequalities and the related complementarity problems. The convergence criteria is also considered. The results proved in this paper represent a significant improvement and refinement of the previously known results.
Quasi-Maxwell interpretation of the spin-curvature coupling
Natario, Jose
2007-01-01
We write the Mathisson-Papapetrou equations of motion for a spinning particle in a stationary spacetime using the quasi-Maxwell formalism and give an interpretation of the coupling between spin and curvature. The formalism is then used to compute equilibrium positions for spinning particles in the NUT spacetime.
Quasi-Maxwell interpretation of the spin-curvature coupling
Natário, José
2007-09-01
We write the Mathisson-Papapetrou equations of motion for a spinning particle in a stationary spacetime using the quasi-Maxwell formalism and give an interpretation of the coupling between spin and curvature. The formalism is then used to compute equilibrium positions for spinning particles in the NUT spacetime.
Institute of Scientific and Technical Information of China (English)
晏红梅; 余同希; 周风华
2011-01-01
对颗粒聚苯乙烯(EPS)泡沫单粒及封闭容器中的大量颗粒整体分别进行了不同加载速率下的准静态压缩实验,获得相应的压缩应力应变曲线.分析了单颗泡沫颗粒内部气体对材料压缩性能的影响,以及大量颗粒用作包装材料时由于内、外部气体被挤出所引起的密度变化对整体应力应变关系的影响.研究表明:EPS泡沫是典型的闭胞材料,单颗颗粒内部气体压力对材料力学行为的影响可以用Ashby等提出的闭胞材料内部气体压力贡献来描述,经过对实验数据拟合,给出了描述单颗材料的考虑颗粒内部封闭气体压力贡献及加载速率影响的本构方程.另一方面,封闭容器里的大量泡沫颗粒的整体力学性能既受颗粒内部气体压力影响,又受颗粒间缝隙气体流动的影响；表观上这种内、外部气体的贡献可以通过材料的表观密度来描述.通过引入整体密度影响因子,定量分析了加载速率对大量颗粒整体的应力应变关系的影响.研究结果对理解大量泡沫颗粒整体的力学性能提供一定的线索.%In this paper,we examined experimentally the quasi-static uniaxial compressive behaviors of a single EPS foam particle and an assembly of many enclosed EPS particles at different loading rates. As representative light-weight closed-cell foam,the mechanical behavior of EPS particle is strongly influenced by the gases enclosed in the cell. The contribution of the gas inside the foam cells is analyzed. For a single foam particle,the contribution of the internal gas on its compressive behavior can be described using a gas model proposed by Ashby et al. A constitutive relationship,considering both effects of the inter gas and the loading rate,is proposed for the compressive behavior of a single EPS particle. For an assembly of enclosed EPS particles,it is shown that both the internal gas and the inter-particle gas affect the mechanical behavior of the
Error in Monte Carlo, quasi-error in Quasi-Monte Carlo
Kleiss, R H
2006-01-01
While the Quasi-Monte Carlo method of numerical integration achieves smaller integration error than standard Monte Carlo, its use in particle physics phenomenology has been hindered by the abscence of a reliable way to estimate that error. The standard Monte Carlo error estimator relies on the assumption that the points are generated independently of each other and, therefore, fails to account for the error improvement advertised by the Quasi-Monte Carlo method. We advocate the construction of an estimator of stochastic nature, based on the ensemble of pointsets with a particular discrepancy value. We investigate the consequences of this choice and give some first empirical results on the suggested estimators.
Institute of Scientific and Technical Information of China (English)
Wu Yang YU; Dong Hua WU; Gang Song LENG
2007-01-01
The purpose of this paper is to generalize the notion of intersection bodies to that of quasi Lp-intersection bodies. The Lp-analogs of the Busemann intersection inequality and the Brunn Minkowski inequality for the quasi Lp-intersection bodies are obtained. The Aleksandrov-Fenchel inequality for the mixed quasi Lp-intersection bodies is also established.
Gavrilik, A M; Rebesh, A P
2010-01-01
We study the properties of sequences of the energy eigenvalues for some generalizations of q-deformed oscillators including the p,q-oscillator, the 3-, 4- and 5-parameter deformed oscillators given in the literature. It is shown that most of the considered models belong to the class of so-called Fibonacci oscillators for which any three consequtive energy levels satisfy the relation E_{n+1}=\\lambda E_n+\\rho E_{n-1} with real constants \\lambda, \\rho. On the other hand, for certain \\mu-oscillator known from 1993 we prove the fact of its non-Fibonacci nature. Possible generalizations of the three-term Fibonacci relation are discussed among which for the \\mu$-oscillator we choose, as the most adequate, the so-called quasi-Fibonacci (or local Fibonacci) property of the energy levels. The property is encoded in the three-term quasi-Fibonacci (QF) relation with non-constant, n-dependent coefficients \\lambda and \\rho. Various aspects of the QF relation are elaborated for the \\mu-oscillator and some of its extensions.
Gavrilik, A. M.; Kachurik, I. I.; Rebesh, A. P.
2010-06-01
We study the properties of the sequences of the energy eigenvalues for some generalizations of q-deformed oscillators including the p, q-oscillator, and the three-, four- and five-parameter deformed oscillators given in the literature. It is shown that most of the considered models belong to the class of so-called Fibonacci oscillators for which any three consecutive energy levels satisfy the relation En + 1 = λEn + ρEn - 1 with real constants λ, ρ. On the other hand, for a certain μ-oscillator known since 1993, we prove its non-Fibonacci nature. Possible generalizations of the three-term Fibonacci relation are discussed, among which for the μ-oscillator we choose, as the most adequate, the so-called quasi-Fibonacci (or local Fibonacci) property of the energy levels. The property is encoded in the three-term quasi-Fibonacci (QF) relation with the non-constant, n-dependent coefficients λ and ρ. Various aspects of the QF relation are elaborated for the μ-oscillator and some of its extensions.
Dieckmann, M E; Meli, A; O'Connor-Drury, L
2009-01-01
Plasma processes close to SNR shocks result in the amplification of magnetic fields and in the acceleration of electrons, injecting them into the diffusive acceleration mechanism. The acceleration of electrons and the B field amplification by the collision of two plasma clouds, each consisting of electrons and ions, at a speed of 0.5c is investigated. A quasi-parallel guiding magnetic field, a cloud density ratio of 10 and a plasma temperature of 25 keV are considered. A quasi-planar shock forms at the front of the dense plasma cloud. It is mediated by a circularly left-hand polarized electromagnetic wave with an electric field component along the guiding magnetic field. Its propagation direction is close to that of the guiding field and orthogonal to the collision boundary. It has a low frequency and a wavelength that equals several times the ion inertial length, which would be indicative of a dispersive Alfven wave close to the ion cyclotron resonance frequency of the left-handed mode (ion whistler), provid...
Split Quasi-adequate Semigroups
Institute of Scientific and Technical Information of China (English)
Xiao Jiang GUO; Ting Ting PENG
2012-01-01
The so-called split IC quasi-adequate semigroups are in the class of idempotent-connected quasi-adequate semigroups.It is proved that an IC quasi-adequate semigroup is split if and only if it has an adequate transversal.The structure of such semigroup whose band of idempotents is regular will be particularly investigated.Our obtained results enrich those results given by McAlister and Blyth on split orthodox semigroups.
Brandes, Ulrik; Strasser, Ben; Wagner, Dorothea
2015-01-01
We introduce Quasi-Threshold Mover (QTM), an algorithm to solve the quasi-threshold (also called trivially perfect) graph editing problem with edge insertion and deletion. Given a graph it computes a quasi-threshold graph which is close in terms of edit count. This edit problem is NP-hard. We present an extensive experimental study, in which we show that QTM is the first algorithm that is able to scale to large real-world graphs in practice. As a side result we further present a simple linear-time algorithm for the quasi-threshold recognition problem.
Energy Technology Data Exchange (ETDEWEB)
Sims, J.R. [Los Alamos National Lab., NM (United States); Naumovich, G.J.; Hoang, T.A.; Dent, P.C. [Everson Electric Co., Bethlehem, PA (United States)
1996-05-01
The National High Magnetic Field Laboratory is completing a quasi-continuous magnet which will sustain a constant field of 60 T for 100 ms in a 32-mm 77 K bore. This magnet consists of 9 mechanically independent, nested, liquid nitrogen-cooled coils which are individually reinforced by high-strength stainless steel outer shells. The coils were wound from rectangular large cross-section, high-strength, high-conductivity copper conductor insulated wtih polyimide and fiberglass tapes. After winding, the coils were inserted into closely fitted, stainless steel reinforcing shells and impregnated with epoxy resin. Design, analysis, material, fabrication and operational issues for this class of magnets are reviewed. Fabrication and quality assurance testing of the 60 T coil set are covered in detail. Future growth of and possible links from this technology to other magnet systems are discussed. Needed improvements in design, analysis, materials, and fabrication are outlined.
Hum, David S.; Fejer, Martin M.
2007-03-01
The use of microstructured crystals in quasi-phasematched (QPM) nonlinear interactions has enabled operation of nonlinear devices in regimes inaccessible to conventional birefringently phasematched media. This review addresses basic aspects of the theory of QPM interactions, microstructured ferroelectrics and semiconductors for QPM, devices based on QPM media, and a series of techniques based on engineering of QPM gratings to tailor spatial and spectral response of QPM interactions. Because it is not possible in a brief review to do justice to the large body of results that have been obtained with QPM media over the past twenty years, the emphasis in this review will be on aspects of QPM interactions beyond their use simply as highly nonlinear alternatives to conventional birefringent media. To cite this article: D.S. Hum, M.M. Fejer, C. R. Physique 8 (2007).
Effective field theory approach to quasi-single field inflation
Noumi, Toshifumi; Yokoyama, Daisuke
2012-01-01
We apply the effective field theory approach to quasi-single field inflation, which contains an additional scalar field with Hubble scale mass other than inflaton. Based on the time-dependent spatial diffeomorphism, which is not broken by the time-dependent background evolution, the most generic action of quasi-single field inflation is constructed up to third order fluctuations. Using the obtained action, the effects of the additional massive scalar field on the primordial curvature perturbations are discussed. In particular, we calculate the power spectrum and discuss the momentum-dependence of three point functions in the squeezed limit for general settings of quasi-single field inflation. Our framework can be also applied to inflation models with heavy particles. We make a qualitative discussion on the effects of heavy particles during inflation and that of sharp turning trajectory in our framework.
Elizarova, Tatiana G
2009-01-01
This book presents two interconnected mathematical models generalizing the Navier-Stokes system. The models, called the quasi-gas-dynamic and quasi-hydrodynamic equations, are then used as the basis of numerical methods solving gas- and fluid-dynamic problems.
Microwave instability in {alpha}-like quasi-isochronous buckets
Energy Technology Data Exchange (ETDEWEB)
Ng, K.Y.
1996-10-01
The problem of microwave instability inside an {alpha}-like quasi- isochronous bucket is addressed. The coupling impedance at wavelengths shorter than the length of the short bunches is found to be not small. The Keil-Schnell criterion is modified for such a bucket using the concept of self-bunching. The mechanism of particle loss during a microwave growth is examined.
Micromechanical Study of fabric evolution in quasi-static deformation of granular materials
Kruyt, Nicolaas P.
2012-01-01
In micromechanical studies of granular materials, relations are investigated between macro-level, continuum characteristics and micro-level, (inter) particle characteristics. For quasi-static deformation of granular materials, the fabric tensor is an important micromechanical characteristic that des
García-Bellido, J; Montes, X; Garcia-Bellido, Juan; Garriga, Jaume; Montes, Xavier
1998-01-01
We show that a large class of two-field models of single-bubble open inflation do not lead to infinite open universes, as it was previously thought, but to an ensemble of very large but finite inflating `islands'. The reason is that the quantum tunneling responsible for the nucleation of the bubble does not occur simultaneously along both field directions and equal-time hypersurfaces in the open universe are not synchronized with equal-density or fixed-field hypersurfaces. The most probable tunneling trajectory corresponds to a zero value of the inflaton field; large values, necessary for the second period of inflation inside the bubble, only arise as localized fluctuations. The interior of each nucleated bubble will contain an infinite number of such inflating regions of comoving size of order $\\gamma^{-1}$, where $\\gamma$ depends on the parameters of the model. Each one of these islands will be a quasi-open universe. Since the volume of the hyperboloid is infinite, inflating islands with all possible values...
Integer Quadratic Quasi-polyhedra
Letchford, Adam N.
This paper introduces two fundamental families of 'quasi-polyhedra' - polyhedra with a countably infinite number of facets - that arise in the context of integer quadratic programming. It is shown that any integer quadratic program can be reduced to the minimisation of a linear function over a quasi-polyhedron in the first family. Some fundamental properties of the quasi-polyhedra are derived, along with connections to some other well-studied convex sets. Several classes of facet-inducing inequalities are also derived. Finally, extensions to the mixed-integer case are briefly examined.
Rogalla, M
1999-01-01
A model for the electric field distribution beneath the Schottky contact in semi-insulating (SI) GaAs particle detectors is developed. The model is based on a field-enhanced electron capture of the EL2-defect. The influence of the compensation mechanism in SI-GaAs on the field distribution, leakage current density and charge collection properties of the detectors will be discussed. The detailed understanding allows then a device optimization. (author)
Bimodal pattern in the fragmentation of Au quasi-projectiles
Bruno, M; D'Agostino, M; Gramegna, F; Gulminelli, F; Vannini, G
2006-01-01
Signals of bimodality have been investigated in experimental data of quasi-projectile decay produced in Au+Au collisions at 35 AMeV. This same data set was already shown to present several signals characteristic of a first order, liquid-gas-like phase transition. For the present analysis, events are sorted in bins of transverse energy of light charged particles emitted by the quasi-target source. A sudden change in the fragmentation pattern is observed from the distributions of the asymmetry of the two largest fragments, and the charge of the largest fragment. This latter distribution shows a bimodal behavior. The interpretation of this signal is discussed.
Practical quasi parton distribution functions
Ishikawa, Tomomi; Qiu, Jian-Wei; Yoshida, Shinsuke
2016-01-01
A completely new strategy to calculate parton distribution functions on the lattice has recently been proposed. In this method, lattice calculable observables, called quasi distributions, are related to normal distributions. The quasi distributions are known to contain power-law UV divergences arise from a Wilson line in the non-local operator, while the normal distributions only have logatithmic UV divergences. We propose possible method to subtract the power divegence to make the matching of the quasi with the normal distributions well-defined. We also demonstrate the matching of the quasi quark distribution between continuum and lattice implementing the power divergence subtraction. The matching calculations are carried out by one-loop perturbation.
Free path lengths in quasi crystals
Wennberg, Bernt
2012-01-01
The Lorentz gas is a model for a cloud of point particles (electrons) in a distribution of scatterers in space. The scatterers are often assumed to be spherical with a fixed diameter $d$, and the point particles move with constant velocity between the scatterers, and are specularly reflected when hitting a scatterer. There is no interaction between point particles. An interesting question concerns the distribution of free path lengths, i.e. the distance a point particle moves between the scattering events, and how this distribution scales with scatterer diameter, scatterer density and the distribution of the scatterers. It is by now well known that in the so-called Boltzmann-Grad limit, a Poisson distribution of scatters leads to an exponential distribution of free path lengths, whereas if the scatterer distribution is periodic, the distribution of free path behaves asymptotically like a Cauchy distribution. This paper considers the case when the scatters are distributed on a quasi crystal, i.e. non periodica...
Quasi-stable injection channels in a wakefield accelerator
Wiltshire-Turkay, Mara; Farmer, John P.; Pukhov, Alexander
2016-05-01
The influence of initial position on the acceleration of externally injected electrons in a plasma wakefield is investigated. Test-particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the wake centre. Particles injected into these channels remain in the wake for a considerable time after dephasing and as a result achieve significantly higher energy than their neighbours. The result is relevant to both the planning and optimisation of experiments making use of external injection.
Quasi-stable injection channels in a wakefield accelerator
Wiltshire-Turkay, Mara; Pukhov, Alexander
2016-01-01
Particle-driven plasma-wakefield acceleration is a promising alternative to conventional electron acceleration techniques, potentially allowing electron acceleration to energies orders of magnitude higher than can currently be achieved. In this work we investigate the dependence of the energy gain on the position at which electrons are injected into the wake. Test particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the centre of the wake. The result is relevant to the planning and tuning of experiments making use of external injection.
Lagrangian multi-particle statistics
DEFF Research Database (Denmark)
Lüthi, Beat; Berg, Jacob; Ott, Søren
2007-01-01
Combined measurements of the Lagrangian evolution of particle constellations and the coarse-grained velocity derivative tensor. partial derivative(u) over tilde (i) /partial derivative x(j) are presented. The data are obtained from three-dimensional particle tracking measurements in a quasi isotr...
Simulation of Dam Break Flow Using Quasi-Molecular Modelling
Directory of Open Access Journals (Sweden)
Sitthichai KULSRI
2007-01-01
Full Text Available We developed a new method based on quasi-molecular modelling to simulate dam break flow. Each quasi-molecule was a group of particles that interacted in a fashion entirely analogous to classical Newtonian molecular interactions. The tank had a base length of 58.4 cm. A water column with a base length of 14.6 cm and a height of 29.2 cm was initially supported on the right side by a vertical plate drawn up rapidly at time t = 0.0 s. The water fell under the influence of gravity acting vertically downwards. The numerical results were validated by quantitative comparison with a previous study. The predicted height and leading edge of the water column corresponded very well with experimental measurements from a previous study. Therefore, our new method based on quasi-molecular modelling showed its ability to adequately simulate a free surface problem.
Quasi-linear dynamics of Weibel instability
Directory of Open Access Journals (Sweden)
O. A. Pokhotelov
2011-11-01
Full Text Available The quasi-linear dynamics of resonant Weibel mode is discussed. It is found that nonlinear saturation of Weibel mode is accompanied by substantial modification of the distribution function in resonant region. With the growth of the wave amplitude the parabolic bell-like form of the electron distribution function in this region converts into flatter shape, such as parabola of the fourth order. This results in significant weakening of the resonant interaction of the wave with particles. The latter becomes weaker and then becomes adiabatic interaction with the bulk of the plasma. This is similar to the case of Bernstein-Greene-Kruskal (Bernstein et al., 1957 electrostatic waves. The mathematical similarity of the Weibel and magnetic mirror instabilities is discussed.
Quasi-least squares regression
Shults, Justine
2014-01-01
Drawing on the authors' substantial expertise in modeling longitudinal and clustered data, Quasi-Least Squares Regression provides a thorough treatment of quasi-least squares (QLS) regression-a computational approach for the estimation of correlation parameters within the framework of generalized estimating equations (GEEs). The authors present a detailed evaluation of QLS methodology, demonstrating the advantages of QLS in comparison with alternative methods. They describe how QLS can be used to extend the application of the traditional GEE approach to the analysis of unequally spaced longitu
Quasi-Periodic Spatiotemporal Filtering
Burghouts, G.J.; Geusebroek, J.M.
2006-01-01
This paper presents the online estimation of temporal frequency to simultaneously detect and identify the quasi-periodic motion of an object. We introduce color to increase discriminative power of a reoccurring object and to provide robustness to appearance changes due to illumination changes. Spati
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
This paper introduces a new inverter topology called a “quasi-Y-source inverter”. The proposed inverter inherits all the advantages of the original Y-source inverter. In addition, the new topology draws continuous current from the source which is required for many renewable sources. It also has d...
Quasi-Graphic Matroids (retracted)
J. Geelen (Jim); A.M.H. Gerards (Bert); G. Whittle (Geoff)
2017-01-01
textabstractFrame matroids and lifted-graphic matroids are two interesting generalizations of graphic matroids. Here, we introduce a new generalization, quasi-graphic matroids, that unifies these two existing classes. Unlike frame matroids and lifted-graphic matroids, it is easy to certify that a
Fluidization of spherocylindrical particles
Mahajan, Vinay V.; Nijssen, Tim M. J.; Fitzgerald, Barry W.; Hofman, Jeroen; Kuipers, Hans; Padding, Johan T.
2017-06-01
Multiphase (gas-solid) flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like) particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.
Fluidization of spherocylindrical particles
Directory of Open Access Journals (Sweden)
Mahajan Vinay V.
2017-01-01
Full Text Available Multiphase (gas-solid flows are encountered in numerous industrial applications such as pharmaceutical, food, agricultural processing and energy generation. A coupled computational fluid dynamics (CFD and discrete element method (DEM approach is a popular way to study such flows at a particle scale. However, most of these studies deal with spherical particles while in reality, the particles are rarely spherical. The particle shape can have significant effect on hydrodynamics in a fluidized bed. Moreover, most studies in literature use inaccurate drag laws because accurate laws are not readily available. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation with the flow, Reynolds number and packing fraction. In this work, the CFD-DEM approach is extended to model a laboratory scale fluidized bed of spherocylinder (rod-like particles. These rod-like particles can be classified as Geldart D particles and have an aspect ratio of 4. Experiments are performed to study the particle flow behavior in a quasi-2D fluidized bed. Numerically obtained results for pressure drop and bed height are compared with experiments. The capability of CFD-DEM approach to efficiently describe the global bed dynamics for fluidized bed of rod-like particles is demonstrated.
Ion motion in the current sheet with sheared magnetic field – Part 1: Quasi-adiabatic theory
Directory of Open Access Journals (Sweden)
A. V. Artemyev
2013-02-01
Full Text Available We present a theory of trapped ion motion in the magnetotail current sheet with a constant dawn–dusk component of the magnetic field. Particle trajectories are described analytically using the quasi-adiabatic invariant corresponding to averaging of fast oscillations around the tangential component of the magnetic field. We consider particle dynamics in the quasi-adiabatic approximation and demonstrate that the principal role is played by large (so called geometrical jumps of the quasi-adiabatic invariant. These jumps appear due to the current sheet asymmetry related to the presence of the dawn–dusk magnetic field. The analytical description is compared with results of numerical integration. We show that there are four possible regimes of particle motion. Each regime is characterized by certain ranges of values of the dawn–dusk magnetic field and particle energy. We find the critical value of the dawn–dusk magnetic field, where jumps of the quasi-adiabatic invariant vanish.
Graphical Models for Quasi-Experimental Designs
Kim, Yongnam; Steiner, Peter M.; Hall, Courtney E.; Su, Dan
2016-01-01
Experimental and quasi-experimental designs play a central role in estimating cause-effect relationships in education, psychology, and many other fields of the social and behavioral sciences. This paper presents and discusses the causal graphs of experimental and quasi-experimental designs. For quasi-experimental designs the authors demonstrate…
Reconstruction of weak quasi-Hopf algebras
Häring, Reto Andreas
1995-01-01
All rational semisimple braided tensor categories are representation categories of weak quasi Hopf algebras. To proof this result we construct for any given category of this kind a weak quasi tensor functor to the category of finite dimensional vector spaces. This allows to reconstruct a weak quasi Hopf algebra with the given category as its representation category.
Quasi-Hyperbolicity and Delay Semigroups
Directory of Open Access Journals (Sweden)
Shard Rastogi
2016-01-01
Full Text Available We study quasi-hyperbolicity of the delay semigroup associated with the equation u′(t=Bu(t+Φut, where ut is the history function and (B,D(B is the generator of a quasi-hyperbolic semigroup. We give conditions under which the associated solution semigroup of this equation generates a quasi-hyperbolic semigroup.
Some applications of stochastic averaging method for quasi Hamiltonian systems in physics
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Many physical systems can be modeled as quasi-Hamiltonian systems and the stochastic averaging method for quasi-Hamiltonian systems can be applied to yield reasonable approximate response sta-tistics.In the present paper,the basic idea and procedure of the stochastic averaging method for quasi Hamiltonian systems are briefly introduced.The applications of the stochastic averaging method in studying the dynamics of active Brownian particles,the reaction rate theory,the dynamics of breathing and denaturation of DNA,and the Fermi resonance and its effect on the mean transition time are reviewed.
Rigidification of quasi-categories
Dugger, Daniel
2009-01-01
We give a new construction for rigidifying a quasi-category into a simplicial category, and prove that it is weakly equivalent to the rigidification given by Lurie. Our construction comes from the use of necklaces, which are simplicial sets obtained by stringing simplices together. As an application of these methods, we use our model to reprove some basic facts from Lurie's "Higher Topos Theory" regarding the rigidification process.
Calculations of quasi-particle spectra of semiconductors under pressure
DEFF Research Database (Denmark)
Christensen, Niels Egede; Svane, Axel; Cardona, M.;
2011-01-01
-gap materials QSGW overestimates the gaps by 0.3–0.8 eV, an error which is ascribed to the omission of ‘‘vertex corrections.’’ This is confirmed by calculations of excitonic effects, by solving the Bethe-Salpeter equation. The LDA error in predicting the binding energy of the Cu-3d states is examined...... and the QSGW and LDA+U approximations are compared. For PbX the spinorbit coupling is included, and it is shown that although LDA gives a reasonable magnitude of the gap at L, only QSGW predicts the correct order of the L+6 and L-6 states and thus the correct sign (negative) of the gap pressure coefficient....... The pressure-induced gap closure leads to linear (Dirac-type) band dispersions around the L point....
Resolving nanophotonic spectra with quasi-normal modes (Conference Presentation)
Powell, David A.
2016-09-01
Many nanophotonic systems are strongly coupled to radiating waves, or suffer significant dissipative losses. Furthermore, they may have complex shapes which are not amenable to closed form calculations. This makes it challenging to determine their modes without resorting to quasi-static or point dipole approximations. To solve this problem, the quasi-normal modes (QNMs) are found from an integral equation model of the particle. These give complex frequencies where excitation can be supported without any incident field. The corresponding eigenvectors yield the modal distributions, which are non-orthogonal due to the non-Hermitian nature of the system. The model based on quasi-normal modes is applied to plasmonic and dielectric particles, and compared with a spherical multipole decomposition. Only with the QNMs is it possible to resolve all features of the extinction spectrum, as each peak in the spectrum can be attributed to a particular mode. In contrast, many of the multipole coefficient have multiple peaks and dips. Furthermore, by performing a multipolar decomposition of each QNM, the spectrum of multipole coefficients is explained in terms of destructive interference between modes of the same multipole order.
Quasi-Optical Control of Intense Microwave Transmission
Hirshfield, Jay L
2005-01-01
This volume assembles the texts of presentations given at the NATO-sponsored Advanced Research Workshop on Quasi-Optical Transmission of High-Power Microwaves, held in Nizhny Novgorod, Russia in February 2004. The presentations bridge a wide range of technical areas, but share common tools of analysis and design. Applications of quasi-optics extend to the use of high-power microwaves—including millimeter-waves— for radar and communications (especially deep space millimeter-wave systems, space debris detection radar, and radar for the detection of small targets moving over heavy clutter); particle accelerators (especially for a future high-acceleration-gradient electron-positron collider); plasma research (especially for controlled nuclear fusion and waste decontamination); and material processing (in particular, ceramic sintering with millimeter-waves, and the coating of metal surfaces with protective dielectric films.). Scientists and engineers working in any of these areas should benefit significantly f...
Quantum quasi-steady states in current transport
D'Agosta, Roberto; Zwolak, Michael; di Ventra, Massimiliano
2007-03-01
We investigate quasi-steady state solutions to transport in quantum systems by finding states which at some time minimize the change in density throughout all space and have a given current density flowing from one part of the system to another [1]. Contrary to classical dynamics, in a quantum mechanical system there are many states with a given energy and particle number which satisfy this minimization criterion. Taking as an example spinless fermions on a one-dimensional lattice, we explicitly show the phase space of a class of quasi-steady states. We also discuss the possibility of coherent and incoherent mixing of these steady state solutions leading to a new type of noise in quantum transport. [1] M. Di Ventra and T.N. Todorov J. Phys. Cond. Matt. 16, 8025 (2004).
Does \\Sigma -\\Sigma -\\alpha Form a Quasi-Bound State?
Htun Oo, H; Kamada, H; Glöckle, W
2004-01-01
We have investigated the possible existence of a quasi-bound state for the \\Sigma -\\Sigma -\\alpha system in the framework of Faddeev calculations. We are particularly interested in the state of total iso-spin T=2, since for an inert \\alpha particle there is no strong conversion to \\Xi -N-\\alpha or \\Lambda -\\Lambda -\\alpha possible. A \\Sigma -\\alpha optical potential based on Nijmegen model D and original \\Sigma -\\Sigma interactions of the series of Nijmegen potentials NSC97 as well a simulated Gaussian type versions thereof are used. Our investigation of the \\Sigma -\\Sigma -\\alpha system leads to a quasi bound state where, depending on the potential parameters, the energy ranges between -1.4 and -2.4 MeV and the level width is about 0.2MeV.
M-quasi-hyponormal composition operators
Directory of Open Access Journals (Sweden)
Pushpa R. Suri
1987-01-01
Full Text Available A necessary and sufficient condition is obtained for M-quasi-hyponormal composition operators. It has also been proved that the class of M-quasi-hyponormal composition operators coincides with the class of M-paranormal composition operators. Existence of M-hyponormal composition operators which are not hyponormal; and M-quasihyponormal composition operators which are not M-hyponormal and quasi-hyponormal are also shown.
Mapping spaces in Quasi-categories
Dugger, Daniel
2009-01-01
We apply the Dwyer-Kan theory of homotopy function complexes in model categories to the study of mapping spaces in quasi-categories. Using this, together with our work on rigidification from [DS1], we give a streamlined proof of the Quillen equivalence between quasi-categories and simplicial categories. Some useful material about relative mapping spaces in quasi-categories is developed along the way.
... Your Health Particle Pollution Public Health Issues Particle Pollution Recommend on Facebook Tweet Share Compartir Particle pollution ... see them in the air. Where does particle pollution come from? Particle pollution can come from two ...
Quasi Periodic Oscillations in Blazars
Indian Academy of Sciences (India)
Alok C. Gupta
2014-09-01
Here we report our recent discoveries of Quasi-Periodic Oscillations (QPOs) in blazars time series data in X-ray and optical electromagnetic bands. Any such detection can give important clues of the location and nature of the processes of emission mechanism. In the case of radio-quiet AGN, the detected QPOs are very likely to be associated with the accretion disk. But in the case of blazars, it may be associated with jets in the high and outburst states, and in the low-state, it is probably associated with the accretion disk. In this brief review, I summarize the recent QPO detections in blazars. There is one strong evidence of QPO detection in XMM–Newton time series data of narrow line Seyfert 1 galaxy RE J1034+396 about which we will also discuss briefly.
Directory of Open Access Journals (Sweden)
F. CESARANO
2013-12-01
Full Text Available The analysis of the definition of monetary aggregates has had a leading role in the debate on money in the sixties and the first half of the seventies. The problems associated with the relationship between money and quasi-money has important implications for various fundamental aspects of monetary theory and monetary policy. In Italy, for reasons related to the peculiar institutional framework, the issue in question has not received much attention. Only recently, as a result of the diffusion of money market instruments, have many parties raised the question regarding the inclusion of these instruments in the definition of the stock of money. After explaining the nature of the problem, the present work provides an empirical analysis of the issue.
Moussessian, Alina
Quasi-optical power combiners such as quasi-optical grids provide an efficient means of combining the output power of many solid-state devices in free space. Unlike traditional power combiners no transmission lines are used, therefore, high output powers with less loss can be achieved at higher frequencies. This thesis investigates four different active antenna grids. The first investigation is into X-band High Electron Mobility Transistor (HEMT) grid amplifiers. Modelling and stability issues of these grids are discussed, and gain and power measurements are presented. A grid amplifier with a maximum efficiency of 22.5% at 10 GHz and a peak gain of 11dB is presented. The second grid is a varactor grid used as a positive feedback network for a grid amplifier to construct a tunable grid oscillator. Reflection measurements for the varactor grid show a tuning range of 1.2 GHz. The third grid is a self- complementary grid amplifier. The goal is to design a new amplifier with a unit cell structure that can be directly modelled using CAD tools. The properties of self- complementary structures are studied and used in the design of this new amplifier grid. The fourth grid is a 12 x 12 terahertz Schottky grid frequency doubler with a measured output power of 24 mW at 1 THz for 3.1-μs 500-GHz input pulses with a peak power of 47 W. A passive millimeter-wave travelling-wave antenna built on a dielectric substrate is also presented. Calculations indicate that the antenna has a gain of 15 dB with 3-dB beamwidths of 10o in the H-plane and 64o in the E-plane. Pattern measurements at 90 GHz support the theory. The antenna is expected to have an impedance in the range of 50/Omega to 80/Omega.
Discrete particle simulation of the homogeneous fluidization of Geldart A particles
Ye, M.; Hoef, van der, M.A.; J.A.M. Kuipers
2004-01-01
The homogeneous fluidization of Geldart A particles has been studied with a 2D soft-sphere discrete particle model. We find that the homogeneous fluidization regime represents a quasi-equilibrium state where the force balance exists at the macroscopic-level, but not at the level of individual particles. The velocity fluctuation of particles is an exponential function of the squared superficial gas velocity in the homogeneous fluidization regime, not a linear function as found by Cody et al.
Perturbative Calculation of Quasi-Potential in Non-equilibrium Diffusions: A Mean-Field Example
Bouchet, Freddy; Gawȩdzki, Krzysztof; Nardini, Cesare
2016-06-01
In stochastic systems with weak noise, the logarithm of the stationary distribution becomes proportional to a large deviation rate function called the quasi-potential. The quasi-potential, and its characterization through a variational problem, lies at the core of the Freidlin-Wentzell large deviations theory (Freidlin and Wentzell, Random perturbations of dynamical systems, 2012). In many interacting particle systems, the particle density is described by fluctuating hydrodynamics governed by Macroscopic Fluctuation Theory (Bertini et al., arXiv:1404.6466 URL"/> , 2014), which formally fits within Freidlin-Wentzell's framework with a weak noise proportional to 1/√{N}, where N is the number of particles. The quasi-potential then appears as a natural generalization of the equilibrium free energy to non-equilibrium particle systems. A key physical and practical issue is to actually compute quasi-potentials from their variational characterization for non-equilibrium systems for which detailed balance does not hold. We discuss how to perform such a computation perturbatively in an external parameter λ , starting from a known quasi-potential for λ =0. In a general setup, explicit iterative formulae for all terms of the power-series expansion of the quasi-potential are given for the first time. The key point is a proof of solvability conditions that assure the existence of the perturbation expansion to all orders. We apply the perturbative approach to diffusive particles interacting through a mean-field potential. For such systems, the variational characterization of the quasi-potential was proven by Dawson and Gartner (Stochastics 20:247-308, 1987; Stochastic differential systems, vol 96, pp 1-10, 1987). Our perturbative analysis provides new explicit results about the quasi-potential and about fluctuations of one-particle observables in a simple example of mean field diffusions: the Shinomoto-Kuramoto model of coupled rotators (Prog Theoret Phys 75:1105-1110, [74
System of Operator Quasi Equilibrium Problems
Directory of Open Access Journals (Sweden)
Suhel Ahmad Khan
2014-01-01
Full Text Available We consider a system of operator quasi equilibrium problems and system of generalized quasi operator equilibrium problems in topological vector spaces. Using a maximal element theorem for a family of set-valued mappings as basic tool, we derive some existence theorems for solutions to these problems with and without involving Φ-condensing mappings.
Semisimplicity of u-Quasi-Hopf Algebra
Institute of Scientific and Technical Information of China (English)
WANG Xiu-rong
2008-01-01
The notions of u-quasi-Hopf algebras and the quantum dimensioa dimu M of a representation M by u are introduced. It is shown that a u-quasi-Hopf algebra H is semisimple if and only if there is a fmite-dimeasional projective H-module P such that dimu P is invertible.
Quasi-Experimental Designs for Causal Inference
Kim, Yongnam; Steiner, Peter
2016-01-01
When randomized experiments are infeasible, quasi-experimental designs can be exploited to evaluate causal treatment effects. The strongest quasi-experimental designs for causal inference are regression discontinuity designs, instrumental variable designs, matching and propensity score designs, and comparative interrupted time series designs. This…
On Judicial and Quasi-Judicial Independence
Comtois, Suzanne; de Graaf, K.J.
2013-01-01
'Principles of judicial and quasi-judicial independence are fundamental to all democracies and yet, the notion of independence is still elusive. What is judicial and quasi-judicial independence and why is it important? From whom and what are the judiciary and other adjudicators to be independent? Is
Minimax discrimination of quasi-Bell states
Energy Technology Data Exchange (ETDEWEB)
Kato, Kentaro [Quantum ICT Research Institute, Tamagawa University, 6-1-1 Tamagawa-gakuen, Machida, Tokyo 194-8610 (Japan)
2014-12-04
An optimal quantum measurement is considered for the so-called quasi-Bell states under the quantum minimax criterion. It is shown that the minimax-optimal POVM for the quasi-Bell states is given by its square-root measurement and is applicable to the teleportation of a superposition of two coherent states.
Quasi experimental designs in pharmacist intervention research.
Krass, Ines
2016-06-01
Background In the field of pharmacist intervention research it is often difficult to conform to the rigorous requirements of the "true experimental" models, especially the requirement of randomization. When randomization is not feasible, a practice based researcher can choose from a range of "quasi-experimental designs" i.e., non-randomised and at time non controlled. Objective The aim of this article was to provide an overview of quasi-experimental designs, discuss their strengths and weaknesses and to investigate their application in pharmacist intervention research over the previous decade. Results In the literature quasi experimental studies may be classified into five broad categories: quasi-experimental design without control groups; quasi-experimental design that use control groups with no pre-test; quasi-experimental design that use control groups and pre-tests; interrupted time series and stepped wedge designs. Quasi-experimental study design has consistently featured in the evolution of pharmacist intervention research. The most commonly applied of all quasi experimental designs in the practice based research literature are the one group pre-post-test design and the non-equivalent control group design i.e., (untreated control group with dependent pre-tests and post-tests) and have been used to test the impact of pharmacist interventions in general medications management as well as in specific disease states. Conclusion Quasi experimental studies have a role to play as proof of concept, in the pilot phases of interventions when testing different intervention components, especially in complex interventions. They serve to develop an understanding of possible intervention effects: while in isolation they yield weak evidence of clinical efficacy, taken collectively, they help build a body of evidence in support of the value of pharmacist interventions across different practice settings and countries. However, when a traditional RCT is not feasible for
Directory of Open Access Journals (Sweden)
Christoph Dönges
1994-01-01
Full Text Available Several statements on quasi-ideals of semirings are given in this paper, where these semirings may have an absorbing element O or not. In Section 2 we characterize regular semirings and regular elements of semi-rings using quasi-ideals (cf. Thms. 2.1, 2.2 and 2.7. In Section 3 we deal with (O−minimal and canonical quasi-ideals. In particular, if the considered semiring S is semiprime or quasi-reflexive, we present criterions which allow to decide easily whether an (O−minimal quasi-ideal of S is canonical (cf. Thms. 3.4 and 3.8. If S is an arbitrary semiring, we prove that for (O−minimal left and right ideals L and R of S the product 〈RL〉⫅L⋂R is either {O} or a canonical quasi-ideal of S (Thm. 3.9. Moreover, for each canonical quasi-ideal Q of a semiring S and each element a∈S, Qa is either {O} or again a canonical quasi-ideal of S (Thm. 3.11, and the product 〈Q1Q2〉 of canonical quasi-ideals Q1, Q2 of S is either {O} or again a canonical quasi-ideal of S (Thm. 3.12. Corresponding results to those given here for semirings are mostly known as well for rings as for semigroups, but often proved by different methods. All proofs of our paper, however, apply simultaneously to semirings, rings and semigroups (cf. Convention 1.1, and we also formulate our results in a unified way for these three cases. The only exceptions are statements on semirings and semigroups without an absorbing element O, which cannot have corresponding statements on rings since each ring has its zero as an absorbing element.
Quasi-one-dimensional scattering in a discrete model
Energy Technology Data Exchange (ETDEWEB)
Valiente, Manuel; Moelmer, Klaus [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)
2011-11-15
We study quasi-one-dimensional scattering of one and two particles with short-range interactions on a discrete lattice model in two dimensions. One of the directions is tightly confined by an arbitrary trapping potential. We obtain the collisional properties of these systems both at finite and zero Bloch quasimomenta, considering as well finite sizes and transversal traps that support a continuum of states. This is made straightforward by using the exact ansatz for the quasi-one-dimensional states from the beginning. In the more interesting case of genuine two-particle scattering, we find that more than one confinement-induced resonances appear due to the nonseparability of the center-of-mass and relative coordinates on the lattice. This is done by solving its corresponding Lippmann-Schwinger-like equation. We characterize the effective one-dimensional interaction and compare it with a model that includes only the effect of the dominant, broadest resonance, which amounts to a single-pole approximation for the interaction coupling constant.
Discrete particle simulation of the homogeneous fluidization of Geldart A particles
Ye, M.; Hoef, van der M.A.; Kuipers, J.A.M.
2004-01-01
The homogeneous fluidization of Geldart A particles has been studied with a 2D soft-sphere discrete particle model. We find that the homogeneous fluidization regime represents a quasi-equilibrium state where the force balance exists at the macroscopic-level, but not at the level of individual partic
Quasi steady MPD performance analysis
Guarducci, F.; Paccani, G.; Lehnert, J.
2011-04-01
Pulsed (quasi-steady) solid propellant magnetoplasmadynamic thruster operation has been investigated both in the self-induced and applied magnetic field cases. Input parameters have been varied in order to analyze performance (in particular impulse bit) dependance on these parameters. The stored energy per shot has been set to four values between 2000 and 3000 J, while magnetic field has been set to six values between 0 and 159 mT. Impulse bit has been evaluated through a thrust stand technique: a brief overview of this method is given together with a description of the data processing procedure. Current measurements allow to use Maeker's formula as a reference for comparison between theoretical and empirical results as well as between self and applied field operation. Appreciable improvements of the thruster impulse bit performance have been noticed for defined sets of stored energy and applied field values. An inductive interaction between the magnet coil and the laboratory facilities, resulting in thrust stand displacement, has been observed: this phenomenon and its consequences on measurements have been investigated. A target used as a ballistic pendulum, insensitive to magnetic coupling, has been employed to acquire a new set of measurements: the results obtained with the target technique show a maximum discrepancy of 5% when compared with the measurements derived from the thrust stand technique. Finally, the thrust stand measurements appear to be affected by the inductive interactions only for very high values of the applied field.
Good B-quasi-Ehresmann semigroups
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
A semigroup S with a sub-band B is called a good B-quasi-Ehresmann semigroup if it is a Bsemiabundant semigroup satisfying the congruence condition such that B((ab)+)abB((ab)*)aB(a*)B(b+)b for all a,b ∈S.We show that every good B-quasi-Ehresmann semigroup has a global representation and a standard representation.As a special case,the structure of good quasi-adequate semigroups is described.
Quasi-Periodically Driven Quantum Systems
Verdeny, Albert; Puig, Joaquim; Mintert, Florian
2016-10-01
Floquet theory provides rigorous foundations for the theory of periodically driven quantum systems. In the case of non-periodic driving, however, the situation is not so well understood. Here, we provide a critical review of the theoretical framework developed for quasi-periodically driven quantum systems. Although the theoretical footing is still under development, we argue that quasi-periodically driven quantum systems can be treated with generalisations of Floquet theory in suitable parameter regimes. Moreover, we provide a generalisation of the Floquet-Magnus expansion and argue that quasi-periodic driving offers a promising route for quantum simulations.
High-energy nuclear optics of polarized particles
Baryshevsky, Vladimir G
2012-01-01
The various phenomena caused by refraction and diffraction of polarized elementary particles in matter have opened up a new research area in the particle physics: nuclear optics of polarized particles. Effects similar to the well-known optical phenomena such as birefringence and Faraday effects, exist also in particle physics, though the particle wavelength is much less than the distance between atoms of matter. Current knowledge of the quasi-optical effects, which exist for all particles in any wavelength range (and energies from low to extremely high), will enable us to investigate different properties of interacting particles (nuclei) in a new aspect. This pioneering book will provide detailed accounts of quasi-optical phenomena in the particle polarization, and will interest physicists and professionals in experimental particle physics.
Some applications of stochastic averaging method for quasi Hamiltonian systems in physics
Institute of Scientific and Technical Information of China (English)
DENG MaoLin; ZHU WeiQiu
2009-01-01
Many physical systems can be modeled as quasi-Hamiltonian systems and the stochastic averaging method for uasi-Hamiltonian systems can be applied to yield reasonable approximate response sta-tistics. In the present paper, the basic idea and procedure of the stochastic averaging method for quasi Hamiltonian systems are briefly introduced. The applications of the stochastic averaging method in studying the dynamics of active Brownian particles, the reaction rate theory, the dynamics of breathing and denaturation of DNA, and the Fermi resonance and its effect on the mean transition time are re-viewed.
Dissipative dynamics in quasi-fission
Oberacker, V E; Simenel, C
2014-01-01
Quasi-fission is the primary reaction mechanism that prevents the formation of superheavy elements in heavy-ion fusion experiments. Employing the time-dependent density functional theory approach we study quasi-fission in the systems $^{40,48}$Ca+$^{238}$U. Results show that for $^{48}$Ca projectiles the quasi-fission is substantially reduced in comparison to the $^{40}$Ca case. This partly explains the success of superheavy element formation with $^{48}$Ca beams. For the first time, we also calculate the repartition of excitation energies of the two fragments in a dynamic microscopic theory. The system is found in quasi-thermal equilibrium only for reactions with $^{40}$Ca. The differences between both systems are interpreted in terms of initial neutron to proton asymmetry of the colliding partners.
Hermite polynomials and quasi-classical asymptotics
Energy Technology Data Exchange (ETDEWEB)
Ali, S. Twareque, E-mail: twareque.ali@concordia.ca [Department of Mathematics and Statistics, Concordia University, Montréal, Québec H3G 1M8 (Canada); Engliš, Miroslav, E-mail: englis@math.cas.cz [Mathematics Institute, Silesian University in Opava, Na Rybníčku 1, 74601 Opava, Czech Republic and Mathematics Institute, Žitná 25, 11567 Prague 1 (Czech Republic)
2014-04-15
We study an unorthodox variant of the Berezin-Toeplitz type of quantization scheme, on a reproducing kernel Hilbert space generated by the real Hermite polynomials and work out the associated quasi-classical asymptotics.
The dynamics of quasi-isometric foliations
Hammerlindl, Andy
2011-01-01
If the stable, center, and unstable foliations of a partially hyperbolic system are quasi-isometric, the system has Global Product Structure. This result also applies to Anosov systems and to other invariant splittings. If a partially hyperbolic system on a manifold with abelian fundamental group has quasi-isometric stable and unstable foliations, the center foliation is without holonomy. If, further, the system has Global Product Structure, then all center leaves are homeomorphic.
Quasi self-adjoint nonlinear wave equations
Energy Technology Data Exchange (ETDEWEB)
Ibragimov, N H [Department of Mathematics and Science, Blekinge Institute of Technology, SE-371 79 Karlskrona (Sweden); Torrisi, M; Tracina, R, E-mail: nib@bth.s, E-mail: torrisi@dmi.unict.i, E-mail: tracina@dmi.unict.i [Dipartimento di Matematica e Informatica, University of Catania (Italy)
2010-11-05
In this paper we generalize the classification of self-adjoint second-order linear partial differential equation to a family of nonlinear wave equations with two independent variables. We find a class of quasi self-adjoint nonlinear equations which includes the self-adjoint linear equations as a particular case. The property of a differential equation to be quasi self-adjoint is important, e.g. for constructing conservation laws associated with symmetries of the differential equation. (fast track communication)
Quasi-adiabatic transport in Mercury's magnetotail
Delcourt, Dominique; Malova, Helmi; Zelenyi, Lev
2017-04-01
MESSENGER observations have revealed that the magnetotail of Mercury is fairly dynamical, possibly subjected to series of magnetic field line dipolarization on time scales of a few seconds. Because of the sharp reversal of the magnetic field, ions may not travel adiabatically in this region of space, and their behavior can be organized according to different categories. Among these categories, quasi-adiabatic (Speiser) ions are such that they experience negligible net change of magnetic moment upon crossing of the field reversal and can thus travel back to low altitudes. We examine the robustness of this quasi-adiabatic behavior during magnetic field line dipolarization where ions are subjected to a large induced electric field. We demonstrate that, although this surging electric field possibly yields substantial nonadiabatic heating, quasi-adiabaticity is robust for ions with velocities larger than the peak ExB drift speed, a behavior that we refer to as "strong" quasi-adiabaticity (as opposed to "weak" quasi-adiabaticity that is violated during dipolarization). We show that the impulsive energization of such quasi-adiabatic ions during dipolarization events can lead to prominent energy-time dispersion structures at low altitudes.
Investigating the Role of Earth's Quasi-Satellite Resonance in the Accretion of Interplanetary Dust
Kortenkamp, S.
2012-12-01
We studied the orbital evolution of low inclination asteroidal interplanetary dust particles (IDPs) decaying towards 1 AU under the influence of radiation pressure, PR drag, and solar wind drag. We used a series of β values (the ratio of radiation pressure to central gravity) ranging from 0.0025 up to 0.02. Assuming a composition consistent with astronomical silicate and a particle density of 2.5 g cm-3 these β values correspond to diameters ranging from 200 down to 25 microns, respectively. Simulations with the larger IDPs (>50 microns) typically showed that 100% of the dust particles became temporarily trapped in mean-motion resonances outside Earth's orbit. When trapped in these outer resonances a dust particle's orbital eccentricity significantly increases (sometimes to e > 0.2) while its decay in semi-major axis is halted. Most dust particles eventually slip out of these outer resonances and their orbits continue decaying inwards toward 1 AU. We found that a significant fraction of the initial populations subsequently became trapped in 1:1 co-orbital resonance with Earth. In addition to traditional horseshoe type co-orbitals, IDPs also became trapped as so-called quasi-satellites. About 1% of the smallest IDPs (25 microns) and 10% of the largest (200 microns) became trapped in the quasi-satellite resonance for some length of time. Quasi-satellite IDPs always remain relatively near to Earth, within about 0.2-0.3 AU, and undergo two close-encounters with Earth each year. While resonant perturbations from Earth halt the decay in semi-major axis of quasi-satellite IDPs their eccentricities continue to decrease, forcing the IDPs onto more Earth-like orbits and causing them to spiral closer and closer to Earth. This has dramatic consequences for the relative velocity and distance of closest approach between Earth and the IDPs. After about 104 years in the quasi-satellite resonance IDPs are typically less than 0.1 AU from Earth and consistently coming within about
Spectral properties of quasi-one-dimensional conductors with a finite transverse band dispersion
Energy Technology Data Exchange (ETDEWEB)
Losic, Z Bonacic; Zupanovic, P [Department of Physics, Faculty of Natural Sciences, Mathematics and Kinesiology, University of Split, Teslina 12, 21000 Split (Croatia); Bjelis, A [Department of Physics, Faculty of Science, University of Zagreb, POB 162, 10001 Zagreb (Croatia)], E-mail: agicz@pmfst.hr, E-mail: bjelis@phy.hr
2008-08-13
We determine the one-particle spectral function and the corresponding derived quantities for the conducting chain lattice with finite inter-chain hopping t{sub perpendicular} and three-dimensional long-range Coulomb electron-electron interaction. The standard G{sub 0}W{sub 0} approximation is used. It is shown that, due to the optical character of the anisotropic plasmon dispersion caused by the finite t{sub perpendicular}, a low energy quasi-particle {delta}-peak appears in the spectral function in addition to the hump present at energies of the order of the plasmon energy. Particular attention is devoted to the continuous crossover from the non-Fermi liquid regime to the Fermi liquid regime with increasing t{sub perpendicular}. It is shown that the spectral weight of the hump transfers to the quasi-particle as the optical gap in the plasmon dispersion increases together with t{sub perpendicular}, with the quasi-particle residuum Z behaving like -ln t{sub perpendicular}){sup -1} in the limit t{sub perpendicular} {yields}0. Our approach is appropriate for the wide range of energy scales given by the plasmon energy and the width of the conduction band, and is complementary to the Luttinger liquid techniques that are limited to the low energy regime close to the Fermi surface.
Quasi-idempotent Rota-Baxter operators arising from quasi-idempotent elements
Jian, Run-Qiang
2017-02-01
In this short note, we construct quasi-idempotent Rota-Baxter operators by quasi-idempotent elements and show that every finite dimensional Hopf algebra admits nontrivial Rota-Baxter algebra structures and tridendriform algebra structures. Several concrete examples are provided, including finite quantum groups and Iwahori-Hecke algebras.
Doubles of Quasi-Quantum Groups
Hausser, F; Hausser, Frank; Nill, Florian
1999-01-01
Drinfeld showed that any finite dimensional Hopf algebra \\G extends to a quasitriangular Hopf algebra \\D(\\G), the quantum double of \\G. Based on the construction of a so--called diagonal crossed product developed by the authors, we generalize this result to the case of quasi--Hopf algebras \\G. As for ordinary Hopf algebras, as a vector space the ``quasi--quantum double'' \\D(\\G) is isomorphic to the tensor product of \\G and its dual \\dG. We give explicit formulas for the product, the coproduct, the R--matrix and the antipode on quasi--Hopf algebra. In particular \\D(\\G) becomes an associative algebra containing \\G as a quasi--Hopf subalgebra. On the other hand, \\dG øtimes 1 is not a subalgebra of \\D(\\G) unless the coproduct on \\G is strictly coassociative. It is shown that the category of finite dimensional representations of \\D(\\G) coincides with what has been called the double category of \\G--modules by S. Majid [M2]. Thus our construction gives a concrete realization of Majid's abstract definition of quasi-...
Quasi Distribution Amplitude of Heavy Quarkonia
Jia, Yu
2015-01-01
The recently-proposed quasi distributions point out a promising direction for lattice QCD to investigate the light-cone correlators, such as parton distribution functions (PDF) and distribution amplitudes (DA), directly in the $x$-space. Owing to its excessive simplicity, the heavy quarkonium can serve as an ideal theoretical laboratory to ascertain certain features of quasi-DA. In the framework of non-relativistic QCD (NRQCD) factorization, we compute the order-$\\alpha_s$ correction to both light-cone distribution amplitudes (LCDA) and quasi-DA associated with the lowest-lying quarkonia, with the transverse momentum UV cutoff interpreted as the renormalization scale. We confirm analytically that the quasi-DA of a quarkonium does reduce to the respective LCDA in the infinite-momentum limit. We also observe that, provided that the momentum of a charmonium reaches about 2-3 times its mass, the quasi-DAs already converge to the LCDAs to a decent level. These results might provide some useful guidance for the fut...
Quasi mode-locking of coherent feedback random fiber laser
Ma, R.; Zhang, W. L.; Zeng, X. P.; Yang, Z. J.; Rao, Y. J.; Yao, B. C.; Yu, C. B.; Wu, Y.; Yu, S. F.
2016-12-01
Mode-locking is a milestone in the history of lasers that allows the generation of short light pulses and stabilization of lasers. This phenomenon is known to occur only in standard ordered lasers for long time and until recently it is found that it also occurs in disordered random lasers formed by nanoscale particles. Here, we report the realization of a so-called quasi mode-locking of coherent feedback random fiber laser which consists of a partially disordered linear cavity formed between a point reflector and a random distributed fiber Bragg grating array with an inserted graphene saturable absorber. We show that multi-groups of regular light pulses/sub-pulses with different repetition frequencies are generated within the quasi mode-locking regime through the so-called collective resonances phenomenon in such a random fiber laser. This work may provide a platform to study mode locking as well as pulse dynamic regulation of random lasing emission of coherent feedback disordered structures and pave the way to the development of novel multi-frequency pulse fiber lasers with potentially wide frequency tuning range.
Energy Technology Data Exchange (ETDEWEB)
Misguich, J.H
2004-04-01
As a first step toward a nonlinear renormalized description of turbulence phenomena in magnetized plasmas, the lowest order quasi-linear description is presented here from a unified point of view for collisionless as well as for collisional plasmas in a constant magnetic field. The quasi-linear approximation is applied to a general kinetic equation obtained previously from the Klimontovich exact equation, by means of a generalised Dupree-Weinstock method. The so-obtained quasi-linear description of electromagnetic turbulence in a magnetoplasma is applied to three separate physical cases: -) weak electrostatic turbulence, -) purely magnetic field fluctuations (the classical quasi-linear results are obtained for cosmic ray diffusion in the 'slab model' of magnetostatic turbulence in the solar wind), and -) collisional kinetic equations of magnetized plasmas. This mathematical technique has allowed us to derive basic kinetic equations for turbulent plasmas and collisional plasmas, respectively in the quasi-linear and Landau approximation. In presence of a magnetic field we have shown that the systematic use of rotation matrices describing the helical particle motion allows for a much more compact derivation than usually performed. Moreover, from the formal analogy between turbulent and collisional plasmas, the results derived here in detail for the turbulent plasmas, can be immediately translated to obtain explicit results for the Landau kinetic equation.
Goyal, R.; Sharma, R. P.; Kumar, S.
2017-01-01
A model is proposed to study the dynamics of high-amplitude quasi-electrostatic whistler waves propagating near resonance cone angle and their interaction with low-frequency kinetic Alfvén waves (KAWs) in Earth's radiation belts. The wave dynamics clearly indicates the whistlers having quasi-electrostatic character when propagating close to resonance cone angle. A high-amplitude whistler wave packet is obtained using the present analysis which has also been observed by S/WAVES (STEREO/WAVES) instrument onboard STEREO (Solar Terrestrial Relations Observatory). A numerical simulation technique has been employed to study the localization of quasi-electrostatic whistler waves in radiation belts. The ponderomotive force of pump quasi-electrostatic whistlers (high frequency) is used to excite low-frequency waves (KAWs). The turbulent spectrum obtained using the analysis suggests the presence of quasi-electrostatic whistlers and density fluctuations associated with KAW in radiation belts plasma. The wave localization and steeper spectra could be responsible for particle energization or heating in radiation belts.
The Quasi-Molecular Stage of Ternary Fission
Poenaru, D N; Greiner, W; Hamilton, J H; Ramayya, A V
2000-01-01
We developed a three-center phenomenological model,able to explainqualitatively the recently obtained experimental results concerning thequasimolecular stage of a light-particle accompanied fission process. It wasderived from the liquid drop model under the assumption that the alignedconfiguration, with the emitted particle between the light and heavy fragment,is reached by increasing continuously the separation distance, while the radiiof the heavy fragment and of the light particle are kept constant. In such away,a new minimum of a short-lived molecular state appears in the deformationenergy at a separation distance very close to the touching point. This minimumallows the existence of a short-lived quasi-molecular state, decaying into thethree final fragments.The influence of the shell effects is discussed. Thehalf-lives of some quasimolecular states which could be formed in the $^{10}$Beand $^{12}$C accompanied fission of $^{252}$Cf are roughly estimated to be theorder of 1 ns, and 1 ms, respectively.
On generalized operator quasi-equilibrium problems
Kum, Sangho; Kim, Won Kyu
2008-09-01
In this paper, we will introduce the generalized operator equilibrium problem and generalized operator quasi-equilibrium problem which generalize the operator equilibrium problem due to Kazmi and Raouf [K.R. Kazmi, A. Raouf, A class of operator equilibrium problems, J. Math. Anal. Appl. 308 (2005) 554-564] into multi-valued and quasi-equilibrium problems. Using a Fan-Browder type fixed point theorem in [S. Park, Foundations of the KKM theory via coincidences of composites of upper semicontinuous maps, J. Korean Math. Soc. 31 (1994) 493-519] and an existence theorem of equilibrium for 1-person game in [X.-P. Ding, W.K. Kim, K.-K. Tan, Equilibria of non-compact generalized games with L*-majorized preferences, J. Math. Anal. Appl. 164 (1992) 508-517] as basic tools, we prove new existence theorems on generalized operator equilibrium problem and generalized operator quasi-equilibrium problem which includes operator equilibrium problems.
Weighing the black hole via quasi-local energy
Ha, Yuan K.
2017-08-01
We set to weigh the black holes at their event horizons in various spacetimes and obtain masses which are substantially higher than their asymptotic values. In each case, the horizon mass of a Schwarzschild, Reissner-Nordström, or Kerr black hole is found to be twice the irreducible mass observed at infinity. The irreducible mass does not contain electrostatic or rotational energy, leading to the inescapable conclusion that particles with electric charges and spins cannot exist inside a black hole. This is proposed as the External Energy Paradigm. A higher mass at the event horizon and its neighborhood is obligatory for the release of gravitational waves in binary black hole merging. We describe how these horizon mass values are obtained in the quasi-local energy approach and applied to the black holes of the first gravitational waves GW150914.
Ion Acceleration at the Quasi-Parallel Shock: Injection Unveiled
Sundberg, Torbjörn; Burgess, David; Mazelle, Christian X
2015-01-01
Collisionless shocks are efficient particle accelerators. At Earth, ions with energies exceeding 100 keV are seen upstream of the bow shock when the magnetic geometry is quasi-parallel, and large-scale supernova remnant shocks can accelerate ions into cosmic rays energies. This energization is attributed to diffusive shock acceleration, however, for this process to become active the ions must first be sufficiently energized. How and where this initial acceleration takes place has been one of the key unresolved issues in shock acceleration theory. Using Cluster spacecraft observations, we study the signatures of ion reflection events in the turbulent transition layer upstream of the shock, and with the support of a hybrid simulation of the shock, we show that these reflection signatures are characteristic of the first step in the ion injection process. These reflection events develop in particular in the region where the trailing edge of large-amplitude upstream waves intercept the local shock ramp and the ups...
Some remarks on quasi-Hermitian operators
Energy Technology Data Exchange (ETDEWEB)
Antoine, Jean-Pierre, E-mail: jean-pierre.antoine@uclouvain.be [Institut de Recherche en Mathématique et Physique, Université Catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Trapani, Camillo, E-mail: camillo.trapani@unipa.it [Dipartimento di Matematica e Informatica, Università di Palermo, I-90123, Palermo (Italy)
2014-01-15
A quasi-Hermitian operator is an operator that is similar to its adjoint in some sense, via a metric operator, i.e., a strictly positive self-adjoint operator. Whereas those metric operators are in general assumed to be bounded, we analyze the structure generated by unbounded metric operators in a Hilbert space. Following our previous work, we introduce several generalizations of the notion of similarity between operators. Then we explore systematically the various types of quasi-Hermitian operators, bounded or not. Finally, we discuss their application in the so-called pseudo-Hermitian quantum mechanics.
Stochastic averaging of quasi-Hamiltonian systems
Institute of Scientific and Technical Information of China (English)
朱位秋
1996-01-01
A stochastic averaging method is proposed for quasi-Hamiltonian systems (Hamiltonian systems with light dampings subject to weakly stochastic excitations). Various versions of the method, depending on whether the associated Hamiltonian systems are integrable or nonintegrable, resonant or nonresonant, are discussed. It is pointed out that the standard stochastic averaging method and the stochastic averaging method of energy envelope are special cases of the stochastic averaging method of quasi-Hamiltonian systems and that the results obtained by this method for several examples prove its effectiveness.
ACCURACY ANALYSIS FOR QUASI-CAREY ELEMENT
Institute of Scientific and Technical Information of China (English)
Dongyang SHI; Xiaobin HAO
2008-01-01
In this paper, a new triangular element (Quasi-Carey element) is constructed by the idea of Specht element. It is shown that this Quasi-Carey element possesses a very special property, i.e.,the consistency error is of order O(h2), one order higher than its interpolation error when the exact solution belongs to Ha(Ω). However, the interpolation error and consistency error of Carey element are of order O(h). It seems that the above special property has never been seen for other triangular elements for the second order problems.
Quasi-crystalline geometry for architectural structures
DEFF Research Database (Denmark)
Weizierl, Barbara; Wester, Ture
2001-01-01
Artikel på CD-Rom 8 sider. The quasi-crystal (QC) type of material was discovered in 1983 by Dan Schechtman from Technion, Haifa. This new crystalline structure of material broke totally with the traditional conception of crystals and geometry introducing non-periodic close packing of cells....... The purpose of the paper is to investigate some possibilities for the application of Quasi-Crystal geometry for structures in architecture. The basis for the investigations is A: to use the Golden Cubes (the two different hexahedra consisting of rhombic facets where the length of the diagonals has the Golden...
Orbifold groups, quasi-projectivity and covers
Bartolo, Enrique Artal; Matei, Daniel
2012-01-01
We discuss properties of complex algebraic orbifold groups, their characteristic varieties, and their abelian covers. In particular, we deal with the question of (quasi)-projectivity of orbifold groups. We also prove a structure theorem for the variety of characters of normal-crossing quasi-projective orbifold groups. Finally, we extend Sakuma's formula for the first Betti number of abelian covers of orbifold fundamental groups. Several examples are presented, including a compact orbifold group which is not projective and a Zariski pair of plane projective curves that can be told by considering an unbranched cover of the projective plane with an orbifold structure.
Quasi-Dirac neutrinos at the LHC
Anamiati, G; Nardi, E
2016-01-01
Lepton number violation is searched for at the LHC using same-sign leptons plus jets. The standard lore is that the ratio of same-sign lepton to opposite-sign lepton events, $R_{ll}$, is equal to $R_{ll}=1$ ($R_{ll}=0$) for Majorana (Dirac) neutrinos. We argue that for "quasi-Dirac" neutrinos, $R_{ll}$ can have any value between 0 and 1, the precise value being controlled by the mass splitting versus the width of the quasi-Dirac resonances. A measurement of $R_{ll}\
Quasi-quantum groups from strings
Jureit, J -H
2007-01-01
Motivated by string theory on the orbifold ${\\cal M}/G$ in presence of a Kalb-Ramond field strength $H$, we define the operators that lift the group action to the twisted sectors. These operators turn out to generate the quasi-quantum group $D_{\\omega}[G]$, introduced in the context of conformal field theory by R. Dijkgraaf, V. Pasquier and P. Roche, with $\\omega$ a 3-cocycle determined by a series of cohomological equations in a tricomplex combining de Rham, \\u{C}ech and group cohomologies. We further illustrate some properties of the quasi-quantum group from a string theoretical point of view.
Categorification and Quasi-Hopf Algebras
Institute of Scientific and Technical Information of China (English)
常文静; 王志玺; 吴可; 杨紫峰
2011-01-01
We categorify the notion of coalgebras by imposing a co-associative law up to some isomorphisms on the co-multiplication map and requiring that these isomorphisms satisfy certairl law of their own, which is called the copentagon identity. We also set up a 2-category of 2-coalgebras. The purpose of this study is from the idea of reconsidering the quasi-Hopf algebras by the categorification process, so that we can study the theory of quasi-Hopf algebras and their representations in some new framework of higher category theory in natural ways.
Occupation of quasi-bound states by electrons in a Schwarzschild field
Energy Technology Data Exchange (ETDEWEB)
Galtsov, D.V.; Pomerantseva, G.V.; Chizhov, G.A.
1983-08-01
It is noted that quasi-steady states at energies omega less than mu exist near a Schwarzschild black hole. The occupation of these states by massive spinor particles is examined in the Pauli approximation for small black holes (mu)(M) much less than 1. It is shown that, as in the case of a scalar field, the occupation process is a thermal one. 7 references.
Quasi-periodic solutions of nonlinear beam equations with quintic quasi-periodic nonlinearities
Directory of Open Access Journals (Sweden)
Qiuju Tuo
2015-01-01
Full Text Available In this article, we consider the one-dimensional nonlinear beam equations with quasi-periodic quintic nonlinearities $$ u_{tt}+u_{xxxx}+(B+ \\varepsilon\\phi(tu^5=0 $$ under periodic boundary conditions, where B is a positive constant, $\\varepsilon$ is a small positive parameter, $\\phi(t$ is a real analytic quasi-periodic function in t with frequency vector $\\omega=(\\omega_1,\\omega_2,\\dots,\\omega_m$. It is proved that the above equation admits many quasi-periodic solutions by KAM theory and partial Birkhoff normal form.
Quasi-eikonal and quasi-U-matrix unitarization schemes beyond the Black Disk Limit
Martynov, E
2014-01-01
Quasi-eikonal and quasi-U-matrix unitarization of the standard Regge-pole amplitude for ${\\alpha}(0)>1$ have been considered. We show that some violation of unitarity even at high energy exists in both models. We have found in quasi-eikonal model a bump-oscillation structure of ${\\rm Im}H(s,b)$ at large values of impact parameter $b$ but where ${\\rm Im}H(s,b)$ is closed to the maximal value. We argue that it is possible to choose the parameter regulating deviation of generalized models from pure eikonal or U-matrix modes in order to restore unitarity.
Differential Inequalities, Normality and Quasi-Normality
Liu, Xiaojun; Pang, Xuecheng
2011-01-01
We prove that if D is a domain in C, alpha>1 and c>0, then the family F of functions meromorphic in D such that |f'(z)|/(1+|f(z)|^alpha)>c for every z in D is normalin D. For alpha=1, the same assumptions imply quasi-normality but not necessarily normality.
Model checking Quasi Birth Death processes
Remke, A.K.I.
2004-01-01
Quasi-Birth Death processes (QBDs) are a special class of infinite state CTMCs that combines a large degree of modeling expressiveness with efficient solution methods. This work adapts the well-known stochastic logic CSL for use on QBDs as CSL and presents model checking algorithms for so-called lev
q-exchangeability via quasi-invariance
Gnedin, A.V.; Olshanski, G.
2010-01-01
For positive q is not 1, the q-exchangeability of an infinite random word is introduced as quasi-invariance under permutations of letters, with a special cocycle which accounts for inversions in the word. This framework allows us to extend the q-analog of de Finetti’s theorem for binary sequences—se
Quasi-crystalline geometry for architectural structures
DEFF Research Database (Denmark)
Wester, Ture; Weinzieri, Barbara
The quasi-crystal (QC) type of material was discovered in 1983 by Dan Schechtman from Technion, Haifa. This new crystalline structure of material broke totally with the traditional conception of crystals and geometry introducing non-periodic close packing of cells with fivefold symmetry in 3D space...
Survival in a quasi-death process
Doorn, van Erik A.; Pollett, Philip K.
2008-01-01
We consider a Markov chain in continuous time with an absorbing coffin state and a finite set $S$ of transient states. When $S$ is irreducible the limiting distribution of the chain as $t \\to\\infty,$ conditional on survival up to time $t,$ is known to equal the (unique) quasi-stationary distribution
Perfect and Quasi-Perfect Lattice Actions
Bietenholz, W
1998-01-01
Perfect lattice actions are exiting with several respects: they provide new insight into conceptual questions of the lattice regularization, and quasi-perfect actions could enable a great leap forward in the non-perturbative solution of QCD. We try to transmit a flavor of them, also beyond the lattice community.
A characterization of quasi-rational polygons
Bedaride, Nicolas
2012-11-01
The aim of this paper is to study quasi-rational polygons related to the outer billiard. We compare different notions introduced in Gutkin and Simányi (1992 Commun. Math. Phys. 143 431-49) and Schwartz (2009 Outer Billiards on Kites (Annals of Mathematics Studies vol 171) (Princeton, NJ: Princeton University Press)) and make a synthesis of them.
Institute of Scientific and Technical Information of China (English)
范志勇; 魏俊潮; 李立斌
2009-01-01
Let R be a ring and M a R-bimodule. If eR(1- e)Me = eM(1- e)Re = 0 for every element e∈E E(R), then M is called quasi-Abel module, where E(R) is the set of all idempotent elements of R. If R as R-bimodule is quasi-Abel module, then R is called a quasi-Abel ring. This article proves some main results as follows: ① R is a quasi-Abel ring if and only if for any element a∈N(R), e∈ E(R), ea = 0 implies eRae=0; ② R is an Abel ring if and only if R is a nilpotent reflexive ring and quasi-Abel ring; (3) Suppose σ is an endomorphism of ring R such that σ(e) =e for any e ∈ E(R) , then R is a quasi-Abel ring if and only if R(σ) is quasi-Abel module.%设R是一个环,M是双R-模.若对每个e∈E(R),有eR(1-e)Me=eM(1-e)Re=0,则称M为拟Abel模,这里E(R)表示R的幂等元集合.若R-双模R是拟Abel的,则称R为拟Abel环.证明了如下结果:①R为拟Abel环当且仅当对任意的a∈N(R),e∈E(R),ea=0蕴涵eRae=0,这里N(R)表示R的幂零元集合;②R为Abel环当且仅当R为幂零自反环和拟Abel环;③设σ为环R的环自同态映射且满足条件: (A)e∈E(R),σ(e)=e,则R为拟Abel环当且仅当R(σ)为拟Abel模.
Slow dynamics in a quasi-two-dimensional binary complex plasma
Du, Cheng-Ran; Thomas, Hubertus M; Morfill, Gregor E; Ivlev, Alexei V
2016-01-01
Slow dynamics in an amorphous quasi-two-dimensional complex plasma, comprised of microparticles of two different sizes, was studied experimentally. The motion of individual particles was observed using video microscopy, and the self part of the intermediate scattering function as well as the mean-squared particle displacement was calculated. The long-time structural relaxation reveals the characteristic behavior near the glass transition. Our results suggest that binary complex plasmas can be an excellent model system to study slow dynamics in classical supercooled fluids.
Quasi-nearly subharmonic functions and quasiconformal mappings
Koskela, Pekka; Manojlović, Vesna
2011-01-01
We prove that the composition of a quasi-nearly subharmonic function and a quasiregular mappings of bounded multiplicity is quasi-nearly subharmonic. Also, we prove that if $u\\circ f$ is quasi-nearly subharmonic for all quasi-nearly subharmonic $u$ and $f$ satisfies some additional conditions, then $f$ is quasiconformal. Similar results are further established for the class of regularly oscillating functions.
Invariant curves of quasi-periodic reversible mappings
Liu, Bin
2005-03-01
We deal with the existence of invariant curves of planar reversible mappings which are quasi-periodic in one of the spatial variables. As applications, we will study the existence of quasi-periodic solutions and the boundedness of solutions for a pendulum-type equation and an asymmetric oscillator depending quasi-periodically on time.
Entropy of continuous maps on quasi-metric spaces
Sayyari, Y.; Molaei, M.; Moghayer, S.M.
2015-01-01
The category of metric spaces is a subcategory of quasi-metric spaces. In this paper the notion of entropy for the continuous maps of a quasi-metric space is extended via spanning and separated sets. Moreover, two metric spaces that are associated to a given quasi-metric space are introduced and the
Nonlocal and quasi-local field theories
Tomboulis, E T
2015-01-01
We investigate nonlocal field theories, a subject that has attracted some renewed interest in connection with nonlocal gravity models. We study, in particular, scalar theories of interacting delocalized fields, the delocalization being specified by nonlocal integral kernels. We distinguish between strictly nonlocal and quasi-local (compact support) kernels and impose conditions on them to insure UV finiteness and unitarity of amplitudes. We study the classical initial value problem for the partial integro-differential equations of motion in detail. We give rigorous proofs of the existence but accompanying loss of uniqueness of solutions due to the presence of future, as well as past, "delays," a manifestation of acausality. In the quantum theory we derive a generalization of the Bogoliubov causality condition equation for amplitudes, which explicitly exhibits the corrections due to nonlocality. One finds that, remarkably, for quasi-local kernels all acausal effects are confined within the compact support regi...
Quasi-neutral theory of epidemic outbreaks.
Directory of Open Access Journals (Sweden)
Oscar A Pinto
Full Text Available Some epidemics have been empirically observed to exhibit outbreaks of all possible sizes, i.e., to be scale-free or scale-invariant. Different explanations for this finding have been put forward; among them there is a model for "accidental pathogens" which leads to power-law distributed outbreaks without apparent need of parameter fine tuning. This model has been claimed to be related to self-organized criticality, and its critical properties have been conjectured to be related to directed percolation. Instead, we show that this is a (quasi neutral model, analogous to those used in Population Genetics and Ecology, with the same critical behavior as the voter-model, i.e. the theory of accidental pathogens is a (quasi-neutral theory. This analogy allows us to explain all the system phenomenology, including generic scale invariance and the associated scaling exponents, in a parsimonious and simple way.
Quasi-classical alternatives in quantum chemistry
Gineityte, V
2014-01-01
The article contains an overview of authors achievements in development of alternative quantum-chemical approaches oriented towards revival of the classical tradition of qualitative chemical thinking instead of obtaining numerical results. The above-mentioned tradition is concluded to be based mainly on principles (rules) of additivity, transferability and locality of molecular properties. Accordingly, model Hamiltonian matrices are used in the approaches under development (called quasi-classical alternatives), wherein algebraic parameters play the role of matrix elements and these are assumed to be transferable for similar atoms and/or atomic orbitals in addition. Further, passing to delocalized descriptions of electronic structures (as usual) is expected to be the main origin of difficulties seeking to formulate quasi-classical alternatives. In the framework of the canonical method of molecular orbitals (MOs), delocalization is shown to be partially avoidable by invoking a recently-suggested approach to sec...
Coupled quasi-homogeneous orthotropic laminates
York, C. B.
2011-09-01
Laminate stacking sequence configurations with quasi-homogeneous properties are derived, whereby the inplane and out-of-plane stiffness properties are concomitant. The stacking sequence configurations contain equal-thickness layers and identical orthotropic properties, differing only by their orientations, which are represented by standard angle- and cross-ply combinations. These simplifying assumptions are in fact representative of the common design practice, but help one to identify and isolate a range of highly complex physical coupling responses, which continue to be referred to collectively in the literature as bending-extension coupling. Dimensionless parameters are developed from which the elements of the extensional, coupling, and bending stiffness matrices are readily calculated for any fibre/resin properties. Feasible domains of lamination parameters are also illustrated for each coupling response to complement abridged listings of stacking sequences. Finally, hygrothermally curvature-stable configurations with quasi-homogeneous properties are identified, thus simplifying the manufacture of laminate configurations possessing tailored mechanical coupling responses.
Quasi-Neutral Theory of Epidemic Outbreaks
Pinto, Oscar A.; Muñoz, Miguel A.
2011-01-01
Some epidemics have been empirically observed to exhibit outbreaks of all possible sizes, i.e., to be scale-free or scale-invariant. Different explanations for this finding have been put forward; among them there is a model for “accidental pathogens” which leads to power-law distributed outbreaks without apparent need of parameter fine tuning. This model has been claimed to be related to self-organized criticality, and its critical properties have been conjectured to be related to directed percolation. Instead, we show that this is a (quasi) neutral model, analogous to those used in Population Genetics and Ecology, with the same critical behavior as the voter-model, i.e. the theory of accidental pathogens is a (quasi)-neutral theory. This analogy allows us to explain all the system phenomenology, including generic scale invariance and the associated scaling exponents, in a parsimonious and simple way. PMID:21760930
Quasi-quantum groups from strings
Energy Technology Data Exchange (ETDEWEB)
Jureit, J-H; Krajewski, T [Centre de Physique Theorique, Campus de Luminy, 13288 Marseille (France)], E-mail: jureit@cpt.univ-mrs.fr, E-mail: krajew@cpt.univ-mrs.fr
2008-02-01
Motivated by string theory on the orbifold M/G in presence of a Kalb-Ramond field strength H, we define the operators that lift the group action to the twisted sectors. These operators turn out to generate the quasi-quantum group D{sub {omega}}[G], introduced in the context of conformal field theory by R. Dijkgraaf, V. Pasquier and P. Roche, with {omega} a 3-cocycle determined by a series of cohomological equations in a tricomplex combining de Rham, Cech and group cohomologies. We further illustrate some properties of the quasi-quantum group from a string theoretical point of view. This work is based on [2], from which a full-fledged treatment may be extracted.
Anisotropy in Quasi-Static Magnetohydrodynamic Turbulence
Verma, Mahendra K.
2017-08-01
In this review we summarise the current status of the quasi-static magnetohydrodynamic turbulence. The energy spectrum is steeper than Kolmogorov’s k -5/3 spectrum due to the decrease of the kinetic energy flux with wavenumber k as a result of Joule dissipation. The spectral index decreases with the increase of interaction parameter. The flow is quasi two-dimensional with strong {{\\mathbf{U}}\\bot} at small k and weak {{U}\\parallel} at large k, where {{\\mathbf{U}}\\bot} and {{U}\\parallel} are the perpendicular and parallel components of velocity relative to the external magnetic field. For small k, the energy flux of {{\\mathbf{U}}\\bot} is negative, but for large k, the energy flux of {{U}\\parallel} is positive. Pressure mediates the energy transfer from {{\\mathbf{U}}\\bot} to {{U}\\parallel} .
Quasi-Static Electric Field Generator
Generazio, Edward R. (Inventor)
2017-01-01
A generator for producing an electric field for with an inspection technology system is provided. The generator provides the required variable magnitude quasi-static electric fields for the "illumination" of objects, areas and volumes to be inspected by the system, and produces human-safe electric fields that are only visible to the system. The generator includes a casing, a driven, non-conducting and triboelectrically neutral rotation shaft mounted therein, an ungrounded electrostatic dipole element which works in the quasi-static range, and a non-conducting support for mounting the dipole element to the shaft. The dipole element has a wireless motor system and a charging system which are wholly contained within the dipole element and the support that uses an electrostatic approach to charge the dipole element.
Threshold fracture energy in solid particle erosion
Argatov, I I; Petrov, Yu V
2012-01-01
The effect of geometrical shape of eroding absolutely rigid particles on the threshold rate of failure has been studied. The Shtaerman-Kilchevsky theory of quasi-static blunt impact, which generalizes Hertz's classical impact theory, is used for modeling the frictionless contact interaction of an axially-symmetric particle with an elastic half-space. The incubation time fracture criterion is applied for predicting surface fracture. It is shown that there exist a critical value of the particle shape parameter such that for all its lower values the fracture energy possesses a nonzero minimal value.
A Quasi Time Optimal Receding Horizon Control
Bania, Piotr
2007-01-01
This paper presents a quasi time optimal receding horizon control algorithm. The proposed algorithm generates near time optimal control when the state of the system is far from the target. When the state attains a certain neighbourhood of the aim, it begins the adaptation of the cost function. The purpose of this adaptation is to move from the time optimal control to the stabilizing control. Sufficient conditions for the stability of the closed loop system and the manner of the adaptation of ...
Periodic solutions of quasi-differential equations
Directory of Open Access Journals (Sweden)
Abdelkader Boucherif
1996-01-01
Full Text Available Existence principles and theorems are established for the nonlinear problem Lu=f(t,u where Lu=−(pu′′+hu is a quasi-differential operator and f is a Carathéodory function. We prove a maximum principle for the operator L and then we show the validity of the upper and lower solution method as well as the monotone iterative technique.
Quasi-optical slot antenna SIS mixers
Zmuidzinas, Jonas; LeDuc, H. G.
1992-01-01
A quasi-optical SIS mixer designed for efficient radiation coupling is described. The mixer uses a twin-slot antenna which has the advantages of a good beam pattern and a low impedance. The radiation and impedance characteristics of the antenna were obtained from a moment-matched calculation. Tapered superconducting microstrip transmission lines are used to carry the radiation from the slot antennas to the tunnel junction. The effective impedance seen by the tunnel junction is quite low, abou...
Perturbative calculation of quasi-normal modes
Siopsis, G
2005-01-01
I discuss a systematic method of analytically calculating the asymptotic form of quasi-normal frequencies. In the case of a four-dimensional Schwarzschild black hole, I expand around the zeroth-order approximation to the wave equation proposed by Motl and Neitzke. In the case of a five-dimensional AdS black hole, I discuss a perturbative solution of the Heun equation. The analytical results are in agreement with the results from numerical analysis.
Mixed quasi-equilibrium-like problems
Directory of Open Access Journals (Sweden)
Muhammad Aslam Noor
2006-01-01
Full Text Available We use the auxiliary principle technique in conjunction with the Bregman function to suggest and analyze a three-step predictor-corrector method for solving mixed quasi-equilibrium-like problems. We also study the convergence criteria of this new method under some mild conditions. As special cases, we obtain various new and known methods for solving variational-like inequalities and related optimization problems.
Quasi-stationary distributions and population processes
Méléard, Sylvie
2011-01-01
This survey concerns the study of quasi-stationary distributions with a specific focus on models derived from ecology and population dynamics. We are concerned with the long time behavior of different stochastic population size processes when 0 is an absorbing point almost surely attained by the process. The hitting time of this point, namely the extinction time, can be large compared to the physical time and the population size can fluctuate for large amount of time before extinction actually occurs. This phenomenon can be understood by the study of quasi-limiting distributions. In this paper, general results on quasi-stationarity are given and examples developed in detail. One shows in particular how this notion is related to the spectral properties of the semi-group of the process killed at 0. Then we study different stochastic population models including nonlinear terms modeling the regulation of the population. These models will take values in countable sets (as birth and death processes) or in continuou...
Generalized Convective Quasi-Equilibrium Closure
Yano, Jun-Ichi; Plant, Robert
2016-04-01
Arakawa and Schubert proposed convective quasi-equilibrium as a basic principle for closing their spectrum mass-flux convection parameterization. In deriving this principle, they show that the cloud work function is a key variable that controls the growth of convection. Thus, this closure hypothesis imposes a steadiness of the cloud work function tendency. This presentation shows how this principle can be generalized so that it can also encompasses both the CAPE and the moisture-convergence closures. Note that the majority of the current mass-flux convection parameterization invokes a CAPE closure, whereas the moisture-convergence closure was extremely popular historically. This generalization, in turn, includes both closures as special cases of convective quasi-equilibrium. This generalization further suggests wide range of alternative possibilities for convective closure. In general, a vertical integral of any function depending on both large-scale and convective-scale variables can be adopted as an alternative closure variables, leading to an analogous formulation as Arakawa and Schubert's convective quasi-equilibrium formulation. Among those, probably the most fascinating possibility is to take a vertical integral of the convective-scale moisture for the closure. Use of a convective-scale variable for closure has a particular appeal by not suffering from a loss of predictability of any large-scale variables. That is a main problem with any of the current convective closures, not only for the moisture-convergence based closure as often asserted.
The analemma criterion: accidental quasi-satellites are indeed true quasi-satellites
Marcos, C de la Fuente
2016-01-01
In the Solar system, a quasi-satellite is an object that follows a heliocentric path with an orbital period that matches almost exactly that of a host body (planetary or not). The trajectory is of such nature that, without being gravitationally attached, the value of the angular separation between host and quasi-satellite as seen from the Sun remains confined within relatively narrow limits for time spans that exceed the length of the host's sidereal orbital period. Here, we show that under these conditions, a quasi-satellite traces an analemma in the sky as observed from the host in a manner similar to that found for geosynchronous orbits. The analemmatic curve (figure-eight-, teardrop-, ellipse-shaped) results from the interplay between the tilt of the rotational axis of the host and the properties of the orbit of the quasi-satellite. The analemma criterion can be applied to identify true quasi-satellite dynamical behaviour using observational or synthetic astrometry and it is tested for several well docume...
Toward a Principled Sampling Theory for Quasi-Orders
Ünlü, Ali; Schrepp, Martin
2016-01-01
Quasi-orders, that is, reflexive and transitive binary relations, have numerous applications. In educational theories, the dependencies of mastery among the problems of a test can be modeled by quasi-orders. Methods such as item tree or Boolean analysis that mine for quasi-orders in empirical data are sensitive to the underlying quasi-order structure. These data mining techniques have to be compared based on extensive simulation studies, with unbiased samples of randomly generated quasi-orders at their basis. In this paper, we develop techniques that can provide the required quasi-order samples. We introduce a discrete doubly inductive procedure for incrementally constructing the set of all quasi-orders on a finite item set. A randomization of this deterministic procedure allows us to generate representative samples of random quasi-orders. With an outer level inductive algorithm, we consider the uniform random extensions of the trace quasi-orders to higher dimension. This is combined with an inner level inductive algorithm to correct the extensions that violate the transitivity property. The inner level correction step entails sampling biases. We propose three algorithms for bias correction and investigate them in simulation. It is evident that, on even up to 50 items, the new algorithms create close to representative quasi-order samples within acceptable computing time. Hence, the principled approach is a significant improvement to existing methods that are used to draw quasi-orders uniformly at random but cannot cope with reasonably large item sets. PMID:27965601
DEFF Research Database (Denmark)
Bekö, Gabriel; Weschler, Charles J.; Wierzbicka, Aneta;
2013-01-01
Particle number (PN) concentrations (10-300 nm in size) were continuously measured over a period of ∼45 h in 56 residences of nonsmokers in Copenhagen, Denmark. The highest concentrations were measured when occupants were present and awake (geometric mean, GM: 22.3 × 103 cm-3), the lowest when...... the homes were vacant (GM: 6.1 × 103 cm-3) or the occupants were asleep (GM: 5.1 × 103 cm-3). Diary entries regarding occupancy and particle related activities were used to identify source events and apportion the daily integrated exposure among sources. Source events clearly resulted in increased PN...... concentrations and decreased average particle diameter. For a given event, elevated particle concentrations persisted for several hours after the emission of fresh particles ceased. The residential daily integrated PN exposure in the 56 homes ranged between 37 × 103 and 6.0 × 106 particles per cm3·h/day (GM: 3...
Energy Technology Data Exchange (ETDEWEB)
Raju, M.R.
1993-09-01
Particle therapy has a long history. The experimentation with particles for their therapeutic application got started soon after they were produced in the laboratory. Physicists played a major role in proposing the potential applications in radiotherapy as well as in the development of particle therapy. A brief review of the current status of particle radiotherapy with some historical perspective is presented and specific contributions made by physicists will be pointed out wherever appropriate. The rationale of using particles in cancer treatment is to reduce the treatment volume to the target volume by using precise dose distributions in three dimensions by using particles such as protons and to improve the differential effects on tumors compared to normal tissues by using high-LET radiations such as neutrons. Pions and heavy ions combine the above two characteristics.
Martin, B R
2008-01-01
An essential introduction to particle physics, with coverage ranging from the basics through to the very latest developments, in an accessible and carefully structured text. Particle Physics: Third Edition is a revision of a highly regarded introduction to particle physics. In its two previous editions this book has proved to be an accessible and balanced introduction to modern particle physics, suitable for those students needed a more comprehensive introduction to the subject than provided by the 'compendium' style physics books. In the Third Edition the standard mod
Energy Technology Data Exchange (ETDEWEB)
Buta, A
2003-02-01
During the collision between the projectile and the target nuclei in the intermediate energy regime (E < 100 MeV/nucleon) two excited nuclei are mainly observed in the exit channel, the quasi projectile (QP) and the quasi target. They disintegrate by particle emission. However, this binary picture is perturbed by the emission of particles and light fragments with velocities intermediate between the projectile velocity and the target one, all along the interaction (midrapidity component). This work aim to determine the excitation energy and the intrinsic angular momentum (or spin) of quasi-projectiles produced in the Ni+Ni and Ni+Au collisions at 52 and 90 MeV/nucleon. The excitation energy is deduced from the kinematical characteristics of particles emitted by the quasi-projectile. They have to be separated from midrapidity particles. Three different scenarios have been used for this purpose. The spin of the quasi-projectile has been extracted from the experimental data by mean of proton and alpha particles multiplicities emitted by the QP in the Ni+Au at 52 MeV/nucleon reaction. The results have been compared to the predictions of a theoretical model based on nucleon transfers. Their evolution is qualitatively reproduced as a function of the violence of the collision. (author)
Computer modeling of test particle acceleration at oblique shocks
Decker, Robert B.
1988-01-01
The present evaluation of the basic techniques and illustrative results of charged particle-modeling numerical codes suitable for particle acceleration at oblique, fast-mode collisionless shocks emphasizes the treatment of ions as test particles, calculating particle dynamics through numerical integration along exact phase-space orbits. Attention is given to the acceleration of particles at planar, infinitessimally thin shocks, as well as to plasma simulations in which low-energy ions are injected and accelerated at quasi-perpendicular shocks with internal structure.
Measurement of quasi-elastic 12C(p,2p) scattering at high momentum transfer
Mardor, Y.; Aclander, J.; Alster, J.; Barton, D.; Bunce, G.; Carroll, A.; Christensen, N.; Courant, H.; Durrant, S.; Gushue, S.; Heppelmann, S.; Kosonovsky, E.; Mardor, I.; Marshak, M.; Makdisi, Y.; Minor, E. D.; Navon, I.; Nicholson, H.; Piasetzky, E.; Roser, T.; Russell, J.; Sutton, C. S.; Tanaka, M.; White, C.; Wu, J.-Y.
1998-10-01
We measured the high-momentum transfer [Q2=4.8 and 6.2 (GeV/c)2] quasi-elastic 12C(p,2p) reaction at θcm~=90 deg for 6 and 7.5 GeV/c incident protons. The momentum components of both outgoing protons and the missing energy and momentum of the proton in the nucleus were measured. We verified the validity of the quasi-elastic picture for ground state momenta up to about 0.5 GeV/c. Transverse and longitudinal momentum distributions of the target proton were measured. They have the same shape with a large momentum tail which is not consistent with independent particle models. We observed that the transverse distribution gets wider as the longitudinal component increases in the beam direction.
Electron acceleration to relativistic energies at a strong quasi-parallel shock wave
Masters, A; Fujimoto, M; Schwartz, S J; Sergis, N; Thomsen, M F; Retinò, A; Hasegawa, H; Lewis, G R; Coates, A J; Canu, P; Dougherty, M K
2013-01-01
Electrons can be accelerated to ultrarelativistic energies at strong (high-Mach number) collisionless shock waves that form when stellar debris rapidly expands after a supernova. Collisionless shock waves also form in the flow of particles from the Sun (the solar wind), and extensive spacecraft observations have established that electron acceleration at these shocks is effectively absent whenever the upstream magnetic field is roughly parallel to the shock surface normal (quasi-parallel conditions). However, it is unclear whether this magnetic dependence of electron acceleration also applies to the far stronger shocks around young supernova remnants, where local magnetic conditions are poorly understood. Here we present Cassini spacecraft observations of an unusually strong solar system shock wave (Saturn's bow shock) where significant local electron acceleration has been confirmed under quasi-parallel magnetic conditions for the first time, contradicting the established magnetic dependence of electron accele...
An Introduction to Control of Chaos for Quasi-Integrable Hamiltonian Systems
Silva, Vilarbo da
2013-01-01
Quasi-integrable Hamiltonian systems are of great interest in many research fields of physics and mathematics. In these systems, the phase space has regular and chaotic trajectories. These trajectories depend in part on the magnitude of perturbation that breaks the integrability of the system. The value of the critical perturbation responsible for this transition is a key element in the control of chaos . In this paper, we explore a procedure for the control in quasi-integrable Hamiltonian systems via canonical map. Initially, we present the basic tools for this study: Hamiltonian map, linearization of the map and Chirikov criterion. Subsequently, we investigated the behavior of a wave-particle interaction front perturbation. Finally, we confront with a numerical analytical approach (iteration of the map) results, showing a good agreement.
Loiko, V. A.; Miskevich, A. A.
2017-01-01
The spectra of the coherent transmission and reflection coefficients of multilayers consisting of the periodic, Fibonacci (quasi-periodic), and Thue-Morse (aperiodic) sequences of plane-parallel monolayers of monodisperse spherical alumina and silica particles are investigated using the quasi-crystalline approximation (QCA) and the transfer matrix method (TMM). The additional opportunities for the transmission and reflection spectra manipulation in comparison with the periodic sequence of monolayers are demonstrated. Photonic band gaps in the spectra of the particulate structures are shifted to the short-wavelength range in comparison with those for systems of homogeneous layers. The shift is larger for the Thue-Morse sequence. The widths of the photonic band gaps for particulate systems are narrower than the ones for multilayers consisting of homogeneous layers of an equivalent volume of matter. The results can be used to create optical, optoelectronics, and photonics devices—for example, multispectral filters, light emitting diodes, solar cells, displays.
Energy Technology Data Exchange (ETDEWEB)
Zhao, Peng [School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Tian, Yu [School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Xiaoning [State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); Institute of Mathematics, Academy of Mathematics and System Science, Chinese Academy of Sciences, Beijing 100190 (China); Sun, Zhao-Yong [School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China)
2015-11-24
It is well-known that there is a geometric correspondence between high-frequency quasi-normal modes (QNMs) and null geodesics (spherical photon orbits). In this paper, we generalize such correspondence to charged scalar field in Kerr-Newman space-time. In our case, the particle and black hole are all charged, so one should consider non-geodesic orbits. Using the WKB approximation, we find that the real part of quasi-normal frequency corresponds to the orbits frequency, the imaginary part of the frequency corresponds to the Lyapunov exponent of these orbits and the eigenvalue of angular equation corresponds to carter constant. From the properties of the imaginary part of quasi-normal frequency of charged massless scalar field, we can still find that the QNMs of charged massless scalar field possess the zero damping modes in extreme Kerr-Newman spacetime under certain condition which has been fixed in this paper.
Pseudo-communication vs Quasi-communication
Directory of Open Access Journals (Sweden)
Елена Константиновна Черничкина
2016-12-01
Full Text Available The article is devoted to the analysis of such specific forms of human interaction as quasi- and pseudo-communication. The authors specify the terms which sometimes are used interchangeably. The aim of the conducted research is to find out and demonstrate existing differences and similarities of these communicative phenomena on the basis of theoretical and empirical analysis of the research material in the Russian and English languages. The authors describe communicative features of these phenomena and consider the reasons for such forms of communication and their increased use at present. The research material is represented fiction extracts, film scripts, jokes, print media, a collection of oral speech records both in Russian and English. The authors make use of the following research methods: definitional analysis (to define the terminology of the research, the method of linguistic observation and introspection (to select the communicative situations, the descriptive-analytical method and the method of comparative analysis (to identify similarities and differences of the target phenomena, and the conversational analysis method (to view productivity and effectiveness of a dialogue, etc. The classification of possible forms of their existence in different discourses is suggested. The authors assume that both pseudo- and quasi-communication are characterized as fictitious forms of human interaction with some noticeable violation of the basic communicative model. Pseudo-communication suffers from the discrepancy of the meaning of a coded and decoded message. The authors put forward the main parameters of scientific classification of it as follows: adequate understanding, intentionality, and the stage of communicative action where the failure takes place. At the same time they stress the necessity to distinguish the cases of pseudo talks from phatic and indirect communication. Quasi-communcation is marked by the lack of a real partner and hence
Quasi-Carbon Fibers and the Composites
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
@@The aim of this report is to study the properties of quasi-carbon fibers (QCF) prepared from the PAN fiber precursor by pyrolysis at a temperature between 400℃ and 1200℃. The resistivity of QCF with different heat-treated temperature (HTT) was investigated by a Hall-35 testing system,and the flexural properties of the result composites (QCFC) are also discussed. In addition, the scanning electronic microscope (SEM) was utilized to observe the surface morphology of QCF and the fracture section of QCFC obtained from flexural testing.
Quasi-exotic open-flavor mesons
Hilger, T
2016-01-01
Meson states with exotic quantum numbers arise naturally in a covariant bound-state framework in QCD. We investigate the consequences of shifting quark masses such that the states are no longer restricted to certain C-parities, but only by J^P. Then, a priori, one can no longer distinguish exotic or conventional states. In order to identify signatures of the different states to look for experimentally, we provide the behavior of masses, leptonic decay constants, and orbital-angular-momentum decomposition of such mesons, as well as the constellations in which they could be found. Most prominently, we consider the case of charged quasi-exotic excitations of the pion.
Is there an quasi-bound state?
Wilkin, C; Chiladze, D; Dymov, S; Hanhart, C; Hartmann, M; Hejny, V; Kacharava, A K; Keshelashvili, I; Khoukaz, A; Maeda, Y; Mersmann, T; Mielke, M; Mikirtychiants, S; Papenbrock, M; Rathmann, F; Rausmann, T; Schleichert, R; Ströher, H; Täschner, A; Valdau, Yu; Wronska, A
2007-01-01
The observed variation of the total cross section for the dp -> 3He eta reaction near threshold means that the magnitude of the s--wave amplitude falls very rapidly with the eta centre--of--mass momentum. It is shown here that recent measurements of the momentum dependence of the angular distribution imply a strong variation also in the phase of this amplitude. Such a behaviour is that expected from a quasi--bound or virtual eta-3He state. The interpretation can be investigated further through measurements of the deuteron or proton analysing powers and/or spin--correlations.
Naturalizing language: human appraisal and (quasi) technology
DEFF Research Database (Denmark)
Cowley, Stephen
2013-01-01
Using contemporary science, the paper builds on Wittgenstein’s views of human language. Rather than ascribing reality to inscription-like entities, it links embodiment with distributed cognition. The verbal or (quasi) technological aspect of language is traced to not action, but human specific...... the verbal aspect of language constrains action and thinking, we also develop customary ways of behaving. Humans extend embodiment by linking real-time activity to actions through which the collectivity imposes a variable degree of control over how individuals realise values....
The Linguistic Relevance of Quasi-Trees
Kroch, A; Kroch, Anthony; Rambow, Owen
1994-01-01
We discuss two constructions (long scrambling and ECM verbs) which challenge most syntactic theories (including traditional TAG approaches) since they seem to require exceptional mechanisms and postulates. We argue that these constructions should in fact be analyzed in a similar manner, namely as involving a verb which selects for a ``defective'' complement. These complements are defective in that they lack certain Case-assigning abilities (represented as functional heads). The constructions differ in how many such abilities are lacking. Following the previous analysis of scrambling of Rambow (1994), we propose a TAG analysis based on quasi-trees.
Quasi-biennial oscillation above 10 mb
Baldwin, Mark P.; Dunkerton, Timothy J.
1991-01-01
It is shown that the quasi-biennial oscillation of the equatorial lower stratosphere was correlated with mean zonal wind in the upper stratosphere, 1979-1990. Correlations were positive near 60 deg N and 30 deg S during Northern Hemisphere (NH) winter and negative in the equatorial upper stratosphere during all seasons. Spatial autocorrelation of mean zonal wind during NH winter was actually largest in the upper stratosphere, between 10 deg S and 62 deg N, due to strong coupling between tropical and extratropical flow at upper levels.
Motility of \\textit{Escherichia coli} in a quasi-two-dimensional porous medium
Sosa-Hernández, Juan Eduardo; Santana-Solano, Jesús
2016-01-01
Bacterial migration through confined spaces is critical for several phenomena like: biofilm formation, bacterial transport in soils, and bacterial therapy against cancer . In the present work, \\textit{E. coli} (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-2-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98 $\\mu m$ spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing trajectory parameters like: instantaneous velocity and turn angle, as well as mean squared displacement, we were able to quantify the effects that different latex particle concentrations have upon bacterial motility. To better understand our results, bacterial trajectories were simulated by means of a phenomenological random-walk model (developed ad hoc), and the simulated ...
Camporeale, Enrico; Zimbardo, G.
2015-01-01
We present a self-consistent Particle-in-Cell simulation of the resonant interactions between anisotropic energetic electrons and a population of whistler waves, with parameters relevant to the Earths radiation belt. By tracking PIC particles, and comparing with test-particle simulations we emphasize the importance of including nonlinear effects and time evolution in the modeling of wave-particle interactions, which are excluded in the resonant limit of quasi- linear theory routinely used in ...
On quasi-similarity of subnormal operators
Institute of Scientific and Technical Information of China (English)
2007-01-01
For a compact subset K in the complex plane, let Rat(K) denote the set of the rational functions with poles off K. Given a finite positive measure with support contained in K, let R2(K,v) denote the closure of Rat(K) in L2(v) and let Sv denote the operator of multiplication by the independent variable z on R2(K, v), that is, Svf = zf for every f∈R2(K, v). SupposeΩis a bounded open subset in the complex plane whose complement has finitely many components and suppose Rat(Ω) is dense in the Hardy space H2(Ω). Letσdenote a harmonic measure forΩ. In this work, we characterize all subnormal operators quasi-similar to Sσ, the operators of the multiplication by z on R2(Ω,σ). We show that for a given v supported onΩ, Sv is quasi-similar to Sσif and only if v/■Ω■σ and log(dv/dσ)∈L1(σ). Our result extends a well-known result of Clary on the unit disk.
On quasi-similarity of subnormal operators
Institute of Scientific and Technical Information of China (English)
Zhi-jian QIU
2007-01-01
For a compact subset K in the complex plane, let Rat(K) denote the set of the rational functions with poles off K. Given a finite positive measure with support contained in K, let R2(K, ν)denote the closure of Rat(K) in L2(ν) and let Sν denote the operator of multiplication by the independent variable z on R2(K,ν), that is, Sνf = zf for every f ∈ R2(K,ν).Suppose Ω is a bounded open subset in the complex plane whose complement has finitely many components and suppose Rat(Ω) is dense in the Hardy space H2(Ω). Let σ denote a harmonic measure for Ω. In this work, we characterize all subnormal operators quasi-similar to Sσ, the operators of the multiplication by z on R2 (-Ω, σ). We show that for a given ν supported on -Ω, Sν is quasi-similar to Sσ if and only if ν|(a)Ω<σ and log (dν/dσ)∈ L1 (σ). Our result extends a well-known result of Clary on the unit disk.
Exophobic quasi-realistic heterotic string vacua
Energy Technology Data Exchange (ETDEWEB)
Assel, Benjamin [Centre de Physique Theorique, Ecole Polytechnique, F-91128 Palaiseau (France); Christodoulides, Kyriakos [Dept. of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL (United Kingdom); Faraggi, Alon E., E-mail: faraggi@amtp.liv.ac.u [Dept. of Mathematical Sciences, University of Liverpool, Liverpool L69 7ZL (United Kingdom); Kounnas, Costas [Lab. Physique Theorique, Ecole Normale Superieure, F-75231 Paris 05 (France); Rizos, John [Department of Physics, University of Ioannina, GR45110 Ioannina (Greece)
2010-01-25
We demonstrate the existence of heterotic string vacua that are free of massless exotic fields. The need to break the non-Abelian GUT symmetries in k=1 heterotic string models by Wilson lines, while preserving the GUT embedding of the weak hypercharge and the GUT prediction sin{sup 2}theta{sub w}(M{sub GUT})=3/8, necessarily implies that the models contain states with fractional electric charge. Such states are severely restricted by observations, and must be confined or sufficiently massive and diluted. We construct the first quasi-realistic heterotic string models in which the exotic states do not appear in the massless spectrum, and only exist, as they must, in the massive spectrum. The SO(10) GUT symmetry is broken to the Pati-Salam subgroup. Our PS heterotic string models contain adequate Higgs representations to break the GUT and electroweak symmetry, as well as colour Higgs triplets that can be used for the missing partner mechanism. By statistically sampling the space of Pati-Salam vacua we demonstrate the abundance of quasi-realistic three generation models that are completely free of massless exotics, rendering it plausible that obtaining realistic Yukawa couplings may be possible in this space of models.
q-Exchangeability via quasi-invariance
Gnedin, Alexander
2009-01-01
For positive q, the q-exchangeability is introduced as quasi-invariance under permutations, with a special cocycle. This allows us to extend the q-analogue of de Finetti's theorem for binary sequences (arXiv:0905.0367) to the general real-valued sequences. In contrast to the classical case with q=1, the order on the reals plays for the q-analogues a significant role. An explicit construction of ergodic q-exchangeable measures involves a random shuffling of the set N={1,2,..} by iteration of the geometric choice. For q distinct from 1, the shuffling yields a probability measure Q that is supported by the group of bijections of N, and has the property of quasi-invariance under both left and right multiplications by finite permutations. We establish connections of the q-exchangeability to certain transient Markov chains on the q-Pascal pyramids and to invariant random flags over the Galois fields.
Quasi-degenerate neutrinos in SO(10)
Joshipura, Anjan S
2010-01-01
Quark lepton universality inherent in grand unified theories based on $SO(10)$ gauge group generically leads to hierarchical neutrino masses. We propose a specific ansatz for the structure of Yukawa matrices in $SO(10)$ models which differ from this generic expectations and lead to quasi degenerate neutrinos through the type-I seesaw mechanism. Consistency of this ansatz is demonstrated through a detailed fits to fermion masses and mixing angles all of which can be explained with reasonable accuracy in a model which uses the Higgs fields transforming as $10,120$ and $\\overline{126}$ representations of $SO(10)$. The proposed ansatz is shown to follow from an extended model based on the three generations of the vector like fermions and an $O(3)$ flavour symmetry. Successful numerical fits are also discussed in earlier proposed models which used combination of the type-I and type-II seesaw mechanisms for obtaining quasi degenerate neutrinos. Large neutrino mixing angles emerge as a consequence of neutrino mass d...
Weak completeness of the Bourbaki quasi-uniformity
Directory of Open Access Journals (Sweden)
M.A. Sánchez Granero
2001-04-01
Full Text Available The concept of semicompleteness (weaker than half-completeness is defined for the Bourbaki quasi-uniformity of the hyperspace of a quasi-uniform space. It is proved that the Bourbaki quasi-uniformity is semicomplete in the space of nonempty sets of a quasi-uniform space (X,U if and only if each stable filter on (X,U* has a cluster point in (X,U. As a consequence the space of nonempty sets of a quasi-pseudometric space is semicomplete if and only if the space itself is half-complete. It is also given a characterization of semicompleteness of the space of nonempty U*-compact sets of a quasi-uniform space (X,U which extends the well known Zenor-Morita theorem.
Biliary Secretion of Quasi-Enveloped Human Hepatitis A Virus
Directory of Open Access Journals (Sweden)
Asuka Hirai-Yuki
2016-12-01
Full Text Available Hepatitis A virus (HAV is an unusual picornavirus that is released from cells cloaked in host-derived membranes. These quasi-enveloped virions (eHAV are the only particle type circulating in blood during infection, whereas only nonenveloped virions are shed in feces. The reason for this is uncertain. Hepatocytes, the only cell type known to support HAV replication in vivo, are highly polarized epithelial cells with basolateral membranes facing onto hepatic (blood sinusoids and apical membranes abutting biliary canaliculi from which bile is secreted to the gut. To assess whether eHAV and nonenveloped virus egress from cells via vectorially distinct pathways, we studied infected polarized cultures of Caco-2 and HepG2-N6 cells. Most (>99% progeny virions were released apically from Caco-2 cells, whereas basolateral (64% versus apical (36% release was more balanced with HepG2-N6 cells. Both apically and basolaterally released virions were predominantly enveloped, with no suggestion of differential vectorial release of eHAV versus naked virions. Basolateral to apical transcytosis of either particle type was minimal (<0.02%/h in HepG2-N6 cells, arguing against this as a mechanism for differences in membrane envelopment of serum versus fecal virus. High concentrations of human bile acids converted eHAV to nonenveloped virions, whereas virus present in bile from HAV-infected Ifnar1−/−Ifngr1−/− and Mavs−/− mice banded over a range of densities extending from that of eHAV to that of nonenveloped virions. We conclude that nonenveloped virions shed in feces are derived from eHAV released across the canalicular membrane and stripped of membranes by the detergent action of bile acids within the proximal biliary canaliculus.
Rheological Properties of Quasi-2D Fluids in Microgravity
Stannarius, Ralf; Trittel, Torsten; Eremin, Alexey; Harth, Kirsten; Clark, Noel; Maclennan, Joseph; Glaser, Matthew; Park, Cheol; Hall, Nancy; Tin, Padetha
2015-01-01
In recent years, research on complex fluids and fluids in restricted geometries has attracted much attention in the scientific community. This can be attributed not only to the development of novel materials based on complex fluids but also to a variety of important physical phenomena which have barely been explored. One example is the behavior of membranes and thin fluid films, which can be described by two-dimensional (2D) rheology behavior that is quite different from 3D fluids. In this study, we have investigated the rheological properties of freely suspended films of a thermotropic liquid crystal in microgravity experiments. This model system mimics isotropic and anisotropic quasi 2D fluids [46]. We use inkjet printing technology to dispense small droplets (inclusions) onto the film surface. The motion of these inclusions provides information on the rheological properties of the films and allows the study of a variety of flow instabilities. Flat films have been investigated on a sub-orbital rocket flight and curved films (bubbles) have been studied in the ISS project OASIS. Microgravity is essential when the films are curved in order to avoid sedimentation. The experiments yield the mobility of the droplets in the films as well as the mutual mobility of pairs of particles. Experimental results will be presented for 2D-isotropic (smectic-A) and 2D-nematic (smectic-C) phases.
Technology for a quasi-GSO satellite communications system
Katagi, T.; Yonezawa, R.; Chiba, I.; Urasaki, S.
1999-01-01
In this paper, a satellite communications system using a Quasi Geostationary Satellite Orbit (Quasi-GSO) is proposed. A 24-hour period Quasi-GSO system could give high quality communication to high latitude regions with its satellites observed from earth stations having high elevation angles. In this paper, a system concept and a deployable flat antenna with light weight antenna elements are described proposing it to be a good candidate for mobile communications satellite use.
Ergodicity of Quasi-birth and Death Processes (Ⅰ)
Institute of Scientific and Technical Information of China (English)
Zhen Ting HOU; Xiao Hua LI
2007-01-01
Quasi-birth and death processes with block tridiagonal matrices find many applications in various areas. Neuts gave the necessary and sufficient conditions for the ordinary ergodicity and found an expression of the stationary distribution for a class of quasi-birth and death processes. In this paper we obtain the explicit necessary and sufficient conditions for l-ergodicity and geometric ergodicity for the class of quasi-birth and death processes, and prove that they are not strongly ergodic.
Pae, Ki Hong; Kim, Chul Min; Nam, Chang Hee
2016-03-01
In laser-driven proton acceleration, generation of quasi-monoenergetic proton beams has been considered a crucial feature of the radiation pressure acceleration (RPA) scheme, but the required difficult physical conditions have hampered its experimental realization. As a method to generate quasi-monoenergetic protons under experimentally viable conditions, we investigated using double-species targets of controlled composition ratio in order to make protons bunched in the phase space in the RPA scheme. From a modified optimum condition and three-dimensional particle-in-cell simulations, we showed by varying the ion composition ratio of proton and carbon that quasi-monoenergetic protons could be generated from ultrathin plane targets irradiated with a circularly polarized Gaussian laser pulse. The proposed scheme should facilitate the experimental realization of ultrashort quasi-monoenergetic proton beams for unique applications in high field science.
The quasi-magnetic-hysteresis behavior of polydisperse ferrofluids with small coupling constant
Energy Technology Data Exchange (ETDEWEB)
Li Jian, E-mail: aizhong@swu.edu.cn [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Lin Yueqiang; Liu Xiaodong; Lin Lihua; Zhang Qingmei; Fu Jun; Chen Longlong [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Li Decai [School of Mechanical and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China)
2012-12-15
The magnetization behaviors of ferrofluids based on {gamma}-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3} composite nanoparticles of size about 11 nm have been investigated. The dipole coupling constant {lambda} of these particles is so small (0.43) that they cannot form aggregates through magnetic interaction alone. Experimental results have shown that for a polydisperse ferrofluid with a particle volume fraction of {phi}{sub V}=2.4%, the magnetization curve exhibits quasi-magnetic-hysteresis behavior, i.e., the demagnetization curve lies above the magnetization curve in a high field. However, for a more dilute {gamma}-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3} ferrofluid with {phi}{sub V}=0.94%, the magnetization curve does not show such behavior. According to the bidisperse model for polydisperse ferrofluids, these magnetization behaviors may be attributed to field-induced effects of self-assembled pre-existing chain-like aggregates. For such pre-existing chain-like aggregates, the orientation of the moments inside the particles is not co-linear, so that during the magnetization and demagnetization processes, their apparent magnetizations at the high-field limit are different. As a consequence, the magnetization curve of the ferrofluid with {phi}{sub V}=2.4% displays quasi-magnetic-hysteresis.
Plasma wakefield acceleration studies using the quasi-static code WAKE
Energy Technology Data Exchange (ETDEWEB)
Jain, Neeraj [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen (Germany); Palastro, John [Icarus Research Inc., P.O. Box 30780, Bethesda, Maryland 20824-0780 (United States); Antonsen, T. M. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Mori, Warren B.; An, Weiming [University of California, Los Angeles, California 90095 (United States)
2015-02-15
The quasi-static code WAKE [P. Mora and T. Antonsen, Phys. Plasmas 4, 217 (1997)] is upgraded to model the propagation of an ultra-relativistic charged particle beam through a warm background plasma in plasma wakefield acceleration. The upgraded code is benchmarked against the full particle-in-cell code OSIRIS [Hemker et al., Phys. Rev. Spec. Top. Accel. Beams 3, 061301 (2000)] and the quasi-static code QuickPIC [Huang et al., J. Comput. Phys. 217, 658 (2006)]. The effect of non-zero plasma temperature on the peak accelerating electric field is studied for a two bunch electron beam driver with parameters corresponding to the plasma wakefield acceleration experiments at Facilities for Accelerator Science and Experimental Test Beams. It is shown that plasma temperature does not affect the energy gain and spread of the accelerated particles despite suppressing the peak accelerating electric field. The role of plasma temperature in improving the numerical convergence of the electric field with the grid resolution is discussed.
Plasma wakefield acceleration studies using the quasi-static code WAKE
Jain, Neeraj; Antonsen, T M; Mori, Warren B; An, Weiming
2014-01-01
The quasi-static code WAKE [P. Mora and T. Antonsen, Phys. Plasmas {\\bf 4}, 217(1997)] is upgraded to model the propagation of an ultra-relativistic charged particle beam through a warm background plasma in plasma wakefield acceleration. The upgraded code is benchmarked against the full particle-in-cell code OSIRIS [Hemker et al., Phys. Rev. ST Accel. Beams {\\bf 3}, 061301(2000)] and the quasi-static code QuickPIC [Huang et al., J. Comp. Phys. {\\bf 217}, 658 (2006)]. The effect of non-zero plasma temperature on the peak accelerating electric field is studied for a two bunch electron beam driver with parameters corresponding to the plasma wakefield acceleration experiments at FACET. It is shown that plasma temperature does not affect the energy gain and spread of the accelerated particles despite suppressing the peak accelerating electric field. The role of plasma temperature in improving the numerical convergence of the electric field with the grid resolution is discussed.
Miele, A.; Wang, T.; Melvin, W. W.
1987-01-01
The near-optimum guidance of an aircraft from quasi-steady flight to quasi-steady flight in a windshear is studied. The take-off problem is considered with reference to flight in a vertical plane; allowance is made for the presence of a downdraft as well as horizontal shear. It is assumed that the power setting is held at the maximum value and that the aircraft is controlled through the angle of attack. While the shear guidance and the initial aftershear guidance use constant gain coefficients, the final aftershear guidance employs a variable gain coefficient. The results show that the guidance scheme for quasi-steady flight recovery yields a transition from quasi-steady flight to quasi-steady flight which is close to that of the optimal trajectory; it guarantees the restoration of the initial quasi-steady state and has good stability properties.
Quasi-steady State Reduction of Molecular Motor-Based Models of Directed Intermittent Search
Newby, Jay M.
2010-02-19
We present a quasi-steady state reduction of a linear reaction-hyperbolic master equation describing the directed intermittent search for a hidden target by a motor-driven particle moving on a one-dimensional filament track. The particle is injected at one end of the track and randomly switches between stationary search phases and mobile nonsearch phases that are biased in the anterograde direction. There is a finite possibility that the particle fails to find the target due to an absorbing boundary at the other end of the track. Such a scenario is exemplified by the motor-driven transport of vesicular cargo to synaptic targets located on the axon or dendrites of a neuron. The reduced model is described by a scalar Fokker-Planck (FP) equation, which has an additional inhomogeneous decay term that takes into account absorption by the target. The FP equation is used to compute the probability of finding the hidden target (hitting probability) and the corresponding conditional mean first passage time (MFPT) in terms of the effective drift velocity V, diffusivity D, and target absorption rate λ of the random search. The quasi-steady state reduction determines V, D, and λ in terms of the various biophysical parameters of the underlying motor transport model. We first apply our analysis to a simple 3-state model and show that our quasi-steady state reduction yields results that are in excellent agreement with Monte Carlo simulations of the full system under physiologically reasonable conditions. We then consider a more complex multiple motor model of bidirectional transport, in which opposing motors compete in a "tug-of-war", and use this to explore how ATP concentration might regulate the delivery of cargo to synaptic targets. © 2010 Society for Mathematical Biology.
$^{11}$Be($\\beta$p), a quasi-free neutron decay?
Riisager, K.; Borge, M.J.G.; Briz, J.A.; Carmona-Gallardo, M.; Fraile, L.M.; Fynbo, H.O.U.; Giles, T.; Gottberg, A.; Heinz, A.; Johansen, J.G.; Jonson, B.; Kurcewicz, J.; Lund, M.V.; Nilsson, T.; Nyman, G.; Rapisarda, E.; Steier, P.; Tengblad, O.; Thies, R.; Winkler, S.R.
2014-01-01
We have observed $\\beta$-delayed proton emission from the neutron-rich nucleus $^{11}$Be by analysing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.4 $\\pm$ 0.6)$\\times$ 10$^{-6}$ the strength of this decay mode, as measured by the B$_\\mathrm{GT}$-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the $^{11}$Be halo neutron into a single-proton state.
$^{11}$Be($\\beta$p), a quasi-free neutron decay?
Riisager, K.; Borge, M.J.G.; Briz, J.A.; Carmona-Gallardo, M.; Fraile, L.M.; Fynbo, H.O.U.; Giles, T.; Gottberg, A.; Heinz, A.; Johansen, J.G.; Jonson, B.; Kurcewicz, J.; Lund, M.V.; Nilsson, T.; Nyman, G.; Rapisarda, E.; Steier, P.; Tengblad, O.; Thies, R.; Winkler, S.R.
2014-01-01
We have observed $\\beta$-delayed proton emission from the neutron-rich nucleus $^{11}$Be by analysing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.4 $\\pm$ 0.6)$\\times$ 10$^{-6}$ the strength of this decay mode, as measured by the B$_\\mathrm{GT}$-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the $^{11}$Be halo neutron into a single-proton state.
Modular invariance and (quasi)-Galois symmetry in conformal field theory
Schellekens, Adrian Norbert
1994-01-01
A brief heuristic explanation is given of recent work with Jürgen Fuchs, Beatriz Gato-Rivera and Christoph Schweigert on the construction of modular invariant partition functions from Galois symmetry in conformal field theory. A generalization, which we call quasi-Galois symmetry, is also described. As an application of the latter, the invariants of the exceptional algebras at level g (for example E_8 level 30) expected from conformal embeddings are presented. [Contribution to the Proceedings of the International Symposium on the Theory of Elementary Particles Wendisch-Rietz, August 30 - September 3, 1994
{sup 11}Be(βp), a quasi-free neutron decay?
Energy Technology Data Exchange (ETDEWEB)
Riisager, K., E-mail: kvr@phys.au.dk [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Forstner, O. [Faculty of Physics, University of Vienna, Währinger Strasse 17, A-1090 Wien (Austria); Stefan-Meyer-Institut für subatomare Physik, Austrian Academy of Sciences, A-1090 Wien (Austria); Borge, M.J.G. [ISOLDE, PH Department, CERN, CH-1211 Geneve 23 (Switzerland); Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Briz, J.A.; Carmona-Gallardo, M. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); Fraile, L.M. [Grupo de Física Nuclear, Universidad Complutense de Madrid, CEI Moncloa, E-28040 Madrid (Spain); Fynbo, H.O.U. [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Giles, T. [EN Department, CERN, CH-1211 Geneve 23 (Switzerland); Gottberg, A. [Instituto de Estructura de la Materia, CSIC, E-28006 Madrid (Spain); EN Department, CERN, CH-1211 Geneve 23 (Switzerland); Heinz, A. [Fundamental Fysik, Chalmers Tekniska Högskola, SE-41296 Göteborg (Sweden); Johansen, J.G. [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Jonson, B. [Fundamental Fysik, Chalmers Tekniska Högskola, SE-41296 Göteborg (Sweden); Kurcewicz, J. [ISOLDE, PH Department, CERN, CH-1211 Geneve 23 (Switzerland); Lund, M.V. [Department of Physics and Astronomy, Aarhus University, DK-8000, Aarhus C (Denmark); Nilsson, T.; Nyman, G. [Fundamental Fysik, Chalmers Tekniska Högskola, SE-41296 Göteborg (Sweden); Rapisarda, E. [ISOLDE, PH Department, CERN, CH-1211 Geneve 23 (Switzerland); and others
2014-05-01
We have observed β{sup −}-delayed proton emission from the neutron-rich nucleus {sup 11}Be by analyzing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.3±0.9)⋅10{sup −6} the strength of this decay mode, as measured by the B{sub GT}-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the {sup 11}Be halo neutron into a single-proton state.
Rockers, Peter C; Tugwell, Peter; Røttingen, John-Arne; Bärnighausen, Till
2017-04-06
Although the number of quasi-experiments conducted by health researchers has increased in recent years, there clearly remains unrealized potential for using these methods for causal evaluation of health policies and programs globally. This article proposes five prescriptions for capturing the full value of quasi-experiments for health research. First, new funding opportunities targeting proposals that use quasi-experimental methods should be made available to a broad pool of health researchers. Second, administrative data from health programs, often amenable to quasi-experimental analysis, should be made more accessible to researchers. Third, training in quasi-experimental methods should be integrated into existing health science graduate programs to increase global capacity to use these methods. Fourth, clear guidelines for primary research and synthesis of evidence from quasi-experiments should be developed. Fifth, strategic investments should be made to continue to develop new innovations in quasi-experimental methodologies. Tremendous opportunities exist to expand the use of quasi-experimental methods to increase our understanding of which health programs and policies work and which do not. Health researchers should continue to expand their commitment to rigorous causal evaluation with quasi-experimental methods, and international institutions should increase their support for these efforts. Copyright © 2017 Elsevier Inc. All rights reserved.
Electromagnetics of active coated nano-particles
DEFF Research Database (Denmark)
Arslanagic, Samel
2013-01-01
This work reviews the fundamental properties of several spherical and cylindrical active coated nano-particles excited by their respective single and/or multiple sources of radiation at optical frequencies. Particular attention is devoted to the influence of the source location and orientation......, the optical gain constant and the nano-particle material composition on the electric and magnetic near fields, the power flow density, the radiated power as well as the directivities. Resonant as well as quasi-transparent states will be emphasized in the discussion....
Dynamics of quasi-stable dissipative systems
Chueshov, Igor
2015-01-01
This book is devoted to background material and recently developed mathematical methods in the study of infinite-dimensional dissipative systems. The theory of such systems is motivated by the long-term goal to establish rigorous mathematical models for turbulent and chaotic phenomena. The aim here is to offer general methods and abstract results pertaining to fundamental dynamical systems properties related to dissipative long-time behavior. The book systematically presents, develops and uses the quasi-stability method while substantially extending it by including for consideration new classes of models and PDE systems arising in Continuum Mechanics. The book can be used as a textbook in dissipative dynamics at the graduate level. Igor Chueshov is a Professor of Mathematics at Karazin Kharkov National University in Kharkov, Ukraine.
Quasi-periodic oscillations of perturbed tori
Parthasarathy, Varadarajan; Kluzniak, Wlodek
2015-01-01
We performed axisymmetric hydrodynamic simulations of perturbed tori orbiting a black hole. The tori in equilibrium were constructed with a constant distribution of angular momentum in a pseudo-Newtonian potential (Klu{\\'z}niak-Lee). Epicyclic motions were triggered by adding sub-sonic velocity fields: radial, vertical and diagonal to the tori in equilibrium. As the perturbed tori evolved in time, we measured $L_{2}$ norm of density and obtained the power spectrum of $L_{2}$ norm which manifested eigenfrequencies of tori modes. We observe a pair of modes which occur in an approximate 3:2 ratio. Results from our simulations are relevant in the context of high-frequency quasi-periodic oscillations (HF QPOs) observed in stellar-mass black hole binaries.
Radiation from ring quasi-arrays
DEFF Research Database (Denmark)
Knudsen, H.
1956-01-01
of the field radiated from homogenous ring arrays of axial dipoles and homogeneous ring quasi-arrays of tangential and radial dipoles; i.e., systems of respectively axial, tangential, and radial dipoles placed equidistantly along a circle and carrying currents of the same numerical value but with a phase...... that increases uniformly along the circle. At first a calculation has been made of the radiated field in the case where the number of elements in the antenna system is infinitely large. After that the influence of the finite number of elements is accounted for by the introduction of correction terms....... Subsequently, the radiation resistance and the gain have been calculated in a few simple cases. The antenna systems described above may display super-gain. On the basis of the theory of super-gain an estimate is made of the smallest permissible radius of these antenna systems. Further an investigation is made...
Quasi-chemical approximation for polyatomic mixtures
Dávila, M V; Matoz-Fernandez, D A; Ramirez-Pastor, A J
2016-01-01
The statistical thermodynamics of binary mixtures of polyatomic species was developed on a generalization in the spirit of the lattice-gas model and the quasi-chemical approximation (QCA). The new theoretical framework is obtained by combining: (i) the exact analytical expression for the partition function of non-interacting mixtures of linear $k$-mers and $l$-mers (species occupying $k$ sites and $l$ sites, respectively) adsorbed in one dimension, and its extension to higher dimensions; and (ii) a generalization of the classical QCA for multicomponent adsorbates and multisite-occupancy adsorption. The process is analyzed through the partial adsorption isotherms corresponding to both species of the mixture. Comparisons with analytical data from Bragg-Williams approximation (BWA) and Monte Carlo simulations are performed in order to test the validity of the theoretical model. Even though a good fitting is obtained from BWA, it is found that QCA provides a more accurate description of the phenomenon of adsorpti...
Saturn's Quasi-Periodic Magnetohydrodynamic Waves
Yates, J. N.; Dougherty, M. K.; Southwood, D. J.; Sulaiman, A.; Masters, A.; Cowley, S. W. H.; Provan, G.; Chen, C. H. K.; Kivelson, M.; Mitchell, D. G.; Hospodarsky, G. B.; Achilleos, N. A.; Sorba, A. M.; Coates, A. J.
2016-12-01
Quasi-periodic 1 hour fluctuations have been recently observed in numerous instruments on-board the Cassini spacecraft. The source of these fluctuations has remained elusive to date. Here we present a case study of such fluctuations observed using the magnetometer instrument during six days in December 2006. We find that magnetic field observations at high-latitudes have small scale ( 0.4 nT) Alfvénic fluctuations present and these fluctuations are concentrated in wave-packets similar to those observed in Kleindienst et al., 2009. The observed wave-packets recur periodically at the northern magnetic oscillation period. Furthermore, we explore the nature of these fluctuations with regards to the consistency of the 1 h period using a magnetospheric box model. Our model results suggest that the observed magnetic fluctuations are standing second harmonic Alfvén waves within Saturn's outer magnetosphere.
Forces acting in quasi 2d emulsions
Orellana, Carlos; Lowensohn, Janna; Weeks, Eric
We study the forces in a quasi two dimensional emulsion system. Our samples are oil-in-water emulsions confined between two close-spaced parallel plates, so that the oil droplets are deformed into pancake shapes. By means of microscopy, we measure the droplet positions and their deformation, which we can relate to the contact forces due to surface tension. We improve over prior work in our lab, achieving a better force resolution. We use this result to measure and calibrate the viscous forces acting in our system, which fully determine all the forces on the droplets. Our results can be applied to study static configurations of emulsion, as well as faster flows.
Quasi Goldstone fermion as a sterile neutrino
Chun, E J; Smirnov, Yu A
1996-01-01
The existence of sterile neutrino is hinted by simultaneous explanation of diverse neutrino anomalies. We suggest that the quasi Goldstone fermions (QGF) arising in supersymmetric theory as a result of spontaneous breaking of global symmetry like the Peccei-Quinn symmetry or the lepton number symmetry can play a role of the sterile neutrino. The smallness of mass of QGF (m_S \\sim 10^{-3}-10 eV) can be related to the specific choice of superpotential or K\\"ahler potential (e.g., no-scale kinetic terms for certain superfields). Mixing of QGF with neutrinos implies the R-parity violation. It can proceed via the coupling of QGF with the Higgs supermultiplets or directly with the lepton doublet. A model which accounts for the solar and atmospheric anomalies and the dark matter is presented.
Noncommutative integrability, paths and quasi-determinants
Di Francesco, Philippe
2010-01-01
In previous work, we showed that the solution of certain systems of discrete integrable equations, notably $Q$ and $T$-systems, is given in terms of partition functions of positively weighted paths, thereby proving the positive Laurent phenomenon of Fomin and Zelevinsky for these cases. This method of solution is amenable to generalization to non-commutative weighted paths. Under certain circumstances, these describe solutions of discrete evolution equations in non-commutative variables: Examples are the corresponding quantum cluster algebras [BZ], the Kontsevich evolution [DFK09b] and the $T$-systems themselves [DFK09a]. In this paper, we formulate certain non-commutative integrable evolutions by considering paths with non-commutative weights, together with an evolution of the weights that reduces to cluster algebra mutations in the commutative limit. The general weights are expressed as Laurent monomials of quasi-determinants of path partition functions, allowing for a non-commutative version of the positiv...
Optical localization in quasi-periodic multilayers
Vasconcelos, M. S.; Albuquerque, E. L.; Mariz, A. M.
1998-07-01
We investigate the optical transmission spectra of quasi-periodic dielectric multilayer slabs arranged in a fashion that exhibits what has been called deterministic disorders. They can be of the so-called substitutional sequences type, and are characterized by the nature of their Fourier spectrum, which can be dense pure point (e.g. a Fibonacci sequence) or singular continuous (e.g. Thue-Morse and double-period sequences). The transmission coefficients are conveniently derived by using a theoretical model based on the transfer-matrix approach. A comparison between the oblique-incidence optical transmission spectrum and the normal-incidence one shows quite a different transmission behaviours over a particular range of frequency.
Quasi-free photoproduction of {eta}-mesons off the deuteron
Energy Technology Data Exchange (ETDEWEB)
Jaegle, I.; Krusche, B.; Dieterle, M.; Keshelashvili, I.; Kotulla, M.; Maghrbi, Y.; Mertens, T.; Oberle, M.; Pheron, F.; Werthmueller, D.; Witthauer, L. [Univ. Basel (Switzerland). Dept. Physik; Anisovich, A.V.; Bayadilov, D.E.; Nikonov, V.A.; Novinski, D.V.; Sarantsev, A.V. [Helmholtz-Inst. fuer Strahlen- und Kernphysik der Univ. Bonn (Germany); Petersburg Nuclear Physics Inst., Gatchina (Russian Federation); Bacelar, J.C.S.; Castelijns, R.; Loehner, H.; Messchendorp, J.G. [Univ. of Groningen, KVI, Groningen (Netherlands); Bantes, B.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Hillert, W.; Hoeffgen, S.; Kammer, S.; Kleber, V.; Klein, Frank; Klein, Friedrich; Konrad, M.; Menze, D.; Schmieden, H.; Schoch, B.; Suele, A.; Walther, D. [Physikalisches Inst. der Universitaet Bonn (Germany); Bartholomy, O.; Beck, R.; Funke, C.; Gutz, E.; Hoffmeister, P.; Horn, I.; Junkersfeld, J.; Kalinowsky, H.; Klempt, E.; Lang, M.; Schmidt, C.; Sokhoyan, V.; Szczepanek, T.; Wendel, C. [Helmholtz-Inst. fuer Strahlen- und Kernphysik der Univ. Bonn (Germany); Beloglazov, Y.A.; Gridnev, A.B.; Lopatin, I.V.; Sumachev, V.V. [Petersburg Nuclear Physics Inst., Gatchina (Russian Federation); Crede, V. [Florida State Univ., Dept. of Physics, Tallahassee, FL (United States); Gothe, R. [Physikalisches Inst. der Univ. Bonn (Germany); Univ. of South Carolina (United States); Gregor, R.; Lugert, S.; Metag, V.; Nanova, M.; Novotny, R.; Pfeiffer, M.; Trnka, D. [Univ. Giessen, II. Physikalisches Inst., Giessen (Germany); Ostrick, M. [Physikalisches Inst. der Univ. Bonn (Germany); University of Mainz (Germany); Pant, L.M. [Univ. Giessen, II. Physikalisches Inst., Giessen (Germany); BARC, Nuclear Physics Div., Mumbai (India); Pee, H. van; Thoma, U. [Helmholtz-Inst. fuer Strahlen- und Kernphysik der Univ. Bonn (Germany); Univ. Giessen (Germany); Roy, A.; Varma, R. [Univ. Giessen (Germany); Indian Inst. of Technology, Mumbai (India). Dept. of Physics] [and others
2011-08-15
Precise data for quasi-free photoproduction of {eta}-mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5GeV. The {eta}-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to {eta}-production off the free proton. No significant effects beyond the folding of the free cross-section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the {eta}-nucleon pairs reconstructed from the final-state four-momenta of the particles. The total cross-section for quasi-free {eta}-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1GeV of incident photon energy, which is not observed for the proton. This structure is even narrower in the invariant-mass spectrum of the {eta}-neutron pairs. Position and width of the peak in the invariant-mass spectrum are W {approx} 1665 MeV and FWHM {gamma} {approx} 25 MeV. The data are compared to the results of different models. (orig.)
Quasi-free photoproduction of eta-mesons off the deuteron
Jaegle, I; Anisovich, A V; Bacelar, J C S; Bantes, B; Bartholomy, O; Bayadilov, D E; Beck, R; Beloglazov, Y A; Castelijns, R; Crede, V; Dieterle, M; Dutz, H; Elsner, D; Ewald, R; Frommberger, F; Funke, C; Gothe, R; Gregor, R; Gridnev, A B; Gutz, E; Hillert, W; Hoeffgen, S; Hoffmeister, P; Horn, I; Junkersfeld, J; Kalinowsky, H; Kammer, S; Keshelashvili, I; Kleber, V; Klein, Frank; Klein, Friedrich; Klempt, E; Konrad, M; Kotulla, M; Lang, M; Loehner, H; Lopatin, I V; Lugert, S; Maghrbi, Y; Menze, D; Mertens, T; Messchendorp, J G; Metag, V; Nikonov, V A; Nanova, M; Novinski, D V; Novotny, R; Oberle, M; Ostrick, M; Pant, L M; van Pee, H; Pfeiffer, M; Pheron, F; Roy, A; Sarantsev, A V; Schadmand, S; Schmidt, C; Schmieden, H; Schoch, B; Shende, S V; Sokhoyan, V; Suele, A; Sumachev, V V; Szczepanek, T; Thoma, U; Trnka, D; Varma, R; Walther, D; Wendel, C; Werthmueller, D; Witthauer, L
2011-01-01
Precise data for quasi-free photoproduction of $\\eta$ mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5 GeV. The $\\eta$-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to $\\eta$-production off the free proton. No significant effects beyond the folding of the free cross section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the $\\eta$-nucleon pairs reconstructed from the final state four-momenta of the particles. The total cross section for quasi-free $\\eta$-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1 GeV of incident photon energy, which is not observed for...
Lorentz boosted frame simulation of Laser wakefield acceleration in quasi-3D geometry
Yu, Peicheng; Davidson, Asher; Tableman, Adam; Dalichaouch, Thamine; Meyers, Michael D; Tsung, Frank S; Decyk, Viktor K; Fiuza, Frederico; Vieira, Jorge; Fonseca, Ricardo A; Lu, Wei; Silva, Luis O; Mori, Warren B
2015-01-01
When modeling laser wakefield acceleration (LWFA) using the particle-in-cell (PIC) algorithm in a Lorentz boosted frame, the plasma is drifting relativistically at $\\beta_b c$ towards the laser, which can lead to a computational speedup of $\\sim \\gamma_b^2=(1-\\beta_b^2)^{-1}$. Meanwhile, when LWFA is modeled in the quasi-3D geometry in which the electromagnetic fields and current are decomposed into a limited number of azimuthal harmonics, speedups are achieved by modeling three dimensional problems with the computation load on the order of two dimensional $r-z$ simulations. Here, we describe how to combine the speed ups from the Lorentz boosted frame and quasi-3D algorithms. The key to the combination is the use of a hybrid Yee-FFT solver in the quasi-3D geometry that can be used to effectively eliminate the Numerical Cerenkov Instability (NCI) that inevitably arises in a Lorentz boosted frame due to the unphysical coupling of Langmuir modes and EM modes of the relativistically drifting plasma in these simul...
Energy Technology Data Exchange (ETDEWEB)
Stelina, J., E-mail: julius.stelina@fel.uniza.sk [Department of Physics, University of Zilina, Univerzitna 1, 010 26 Zilina (Slovakia); Musil, C. [Department of Physics, University of Zilina, Univerzitna 1, 010 26 Zilina (Slovakia)
2012-05-15
The effect of a quasi-homogeneous external magnetic field on a created and decaying space nanoparticle structure and its distribution in a sample of a magnetic fluid was studied. This space structure was created as a grating by applying an interference field of two crossed Ar laser beams. The magnetic field was formed using two electromagnets and was applied in three main directions of the created nanoparticle grating. The magnetic field oriented parallel to the strips of the grating or perpendicular to the grating plain does not significantly change the shape of it. The magnetic field oriented in the perpendicular direction to the grating plain causes redistribution of the nanoparticles and as a consequence a perpendicular nanoparticle 'quasi-grating' arises. - Highlights: Black-Right-Pointing-Pointer External magnetic field creates a new nanoparticle quasi-grating. Black-Right-Pointing-Pointer We find that the new grating is perpendicular to the original one. Black-Right-Pointing-Pointer We observe a planar grating in the transitional phase of about 15 s. Black-Right-Pointing-Pointer We speculate that the new grating is related to structuralization of particles.
Quasi-SU(3) truncation scheme for even-even sd-shell nuclei
Vargas, C E; Draayer, J P
2000-01-01
The Quasi-SU(3) symmetry was uncovered in full pf and sdg shell-model calculations for both even-even and odd-even nuclei. It manifests itself through a dominance of single-particle and quadrupole-quadrupole terms in the Hamiltonian used to describe well-deformed nuclei. A practical consequence of the quasi-SU(3) symmetry is an efficient basis truncation scheme. In a recent work was shown that when this type of Hamiltonian is diagonalized in an SU(3) basis, only a few irreducible represntations (irreps) of SU(3) are needed to describe the Yrast band, the leading S = 0 irrep augmented with the leading S = 1 irreps in the proton and neutron subspaces. In the present article the quasi-SU(3) truncation scheme is used, in conjunction with a "realistic but schematic" Hamiltonian that includes the most important multipole terms, to describe the energy spectra and B(E2) transition strengths of 20-Ne, 22-Ne, 24-Mg and 28-Si. The effect of the size of the Hilbert space on both sets of observables is discussed, as well ...
Quasi-variational principles of single flexible body dynamics and their applications
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
The reasons for studying single flexible body dynamics are that on one hand,it is the basis of flexible multi-body dynamics.If the theory of the single flexible body dynamics has been deeply studied,the theory of flexible multi-body dynamics will be researched easily.On the other hand,it has its unique and important applications.Quasi-variational principle of non-conservative single flexible body dynamics is established under the cross-link of particle rigid body mechanics and deformable body mechanics.Taking the interceptor as an example,this paper has explained the physical meaning of the quasi-stationary value condition of the quasi-variational principle in non-conservative single flexible body dynamics.Taking the launch of rocket as an example,it has illustrated the features of"one force for two effects"in a single flexible body dynamics.With an example of the extending flexible beam coupled with the spacecraft attitude,it has shown the transition from the single flexible body dynamics to the flexible multi-body dynamics.Finally,a number of related problems are discussed.
Quasi-variational principles of single flexible body dynamics and their applications
Institute of Scientific and Technical Information of China (English)
LIANG LiFu; LIU ShiQuan; ZHOU JianSheng
2009-01-01
The reasons for studying single flexible body dynamics are that on one hand, it is the basis of flexible multi-body dynamics. If the theory of the single flexible body dynamics has been deeply studied, the theory of flexible multi-body dynamics will be researched easily. On the other hand, it has its unique and important applications. Quasi-variational principle of non-conservative single flexible body dynamics is established under the cross-link of particle rigid body mechanics and deformable body mechanics. Taking the interceptor as an example, this paper has explained the physical meaning of the quasi-stationary value condition of the quasi-variational principle in non-conservative single flexible body dynamics. Taking the launch of rocket as an example, it has illustrated the features of "one force for two effects" in s single flexible body dynamics. With an example of the extending flexible beam coupled with the spacecraft attitude, it has shown the transition from the single flexible body dynamics to the flexible multi-body dynamics. Finally, a number of related problems are discussed.
COLLABORATIVE TRACKING VIA PARTICLE FILTER IN WIRELESS SENSOR NETWORKS
Institute of Scientific and Technical Information of China (English)
Yan Zhenya; Zheng Baoyu; Xu Li; Li Shitang
2008-01-01
Target tracking is one of the main applications of wireless sensor networks. Optimized computation and energy dissipation are critical requirements to save the limited resource of the sensor nodes. A framework and analysis for collaborative tracking via particle filter are presented in this paper.Collaborative tracking is implemented through sensor selection, and results of tracking are propagated among sensor nodes. In order to save communication resources, a new Ganssian sum particle filter,called Gaussian sum quasi particle filter, to perform the target tracking is presented, in which only mean and covariance of mixands need to be communicated. Based on the Gaussian sum quasi particle filter, a sensor selection criterion is proposed, which is computationally much simpler than other sensor selection criterions. Simulation results show that the proposed method works well for target tracking.
Diamond lemma for the group graded quasi-algebras
Indian Academy of Sciences (India)
MAMTA BALODI; HUA-LIN HUANG; SHIV DATT KUMAR
2016-08-01
Let $G$ be a group. We prove that every expression in a $G$-graded quasialgebra can be reduced to a unique irreducible form and the irreducible words form abasis for the quasi-algebra. The result obtained is applied to some interesting classes of group graded quasi-algebras like generalized octonions.
POINTWISE SIMULTANEOUS APPROXIMATION BY LEFT GAMMA QUASI-INTERPOLANTS
Institute of Scientific and Technical Information of China (English)
Hongbiao Jiang
2008-01-01
Recently some classical operator quasi-interpolants were introduced to obtain much faster convergence.We consider left Gamma quasi-interpolants and give a pointwise simultaneous approximation equivalence theorem with ω2r(4)λ(f,f)∞ by means of unified the classical modulus and Ditzian-Totick modulus.
A REMARK ON THE QUASI-HARMONIC SPHERES
Institute of Scientific and Technical Information of China (English)
XuDeliang; ZhouChunqin
2002-01-01
Several theorems on the finiteness of energy for quasi-harmonic spheres are proved,some counter-examples which state that the energy of quasi-harmonic sphere may be infinite are given. The results support some conditions of a question posed by Lin Fanghua and Wang Changyou.
Lebesgue-Type inequalities for quasi-greedy bases
Hernández, Eugenio
2011-01-01
We show that for quasi-greedy bases in real Banach spaces the error of the thresholding greedy algorithm of order N is bounded by the best N-term error of approximation times a constant which depends on the democracy functions and the quasi-greedy constant of the basis.
Quasi-Type δ Semigroups with an Adequate Transversal
Institute of Scientific and Technical Information of China (English)
Shou Feng WANG
2011-01-01
In this paper,some properties of quasi-type δ semigroups with an adequate transversal are explored.In particular,abundant semigroups with a cancellative transversal are characterized.Our results generalize and enrich Saito's results on quasi-orthodox semigroups with an inverse transversal.
MULTI-VALUED QUASI VARLATIONAL INCLUSIONS IN BANACH SPACES
Institute of Scientific and Technical Information of China (English)
张石生
2004-01-01
The purpose is to introduce and study a class of more general multivalued quasi variational inclusions in Banach spaces.By using the resolvent operator technique some existence theorem of solutions and iterative approximation for solving this kind of multivalued quasi variational inclusions are established.The results generalize,improve and unify a number of Noor's and others' recent results.
Quasi-periodic solutions of the Boomeron equation
Martini, R.; Wesselius, W.
1985-01-01
The quasi-periodic solutions for the Boomeron equation are determined by means of function-theoretical methods related to Riemann surfaces and theta functions. Also determined are the so-called Boomerons as degenerations of the quasi-periodic solutions. Moreover it is indicated that there are no hig
On Quasi E-Convex Bilevel Programming Problem
Directory of Open Access Journals (Sweden)
E. A. Youness
2005-01-01
Full Text Available Bilevel programming problems involve two optimization problems where the data of the first one is implicity determined by the solution of the second. This study introduces the notions of E-convexity and quasi E-convexity in bilevel programming problems to generalize quasi convex bilevel programming problems.
A New Perturbed Algorithm for Generalized Quasi-Variational Inclusions
Institute of Scientific and Technical Information of China (English)
徐海丽; 郭兴明
2003-01-01
In this paper, a perturbed iterative method for solving a general class of quasi-variational inclusions was studied. The existence and convergence of solution were proved. Furthermore, a new iterative method for solving a general class of quasi-variational inclusions was proposed. The continuity of the perturbed solution was also proved for a parametric variational inclusion problem. Several special cases were discussed.
E x B shearing rate in quasi-symmetric plasmas
Energy Technology Data Exchange (ETDEWEB)
Hahm, T.S.
1997-06-20
The suppression of turbulence by the E x B shear is studied in systems with quasi-symmetry using the nonlinear analysis of eddy decorrelation previously utilized in finite aspect ratio tokamak plasmas. The analytically derived E x B shearing rate which contains the relevant geometric dependence can be used for quantitative assessment of the fluctuation suppression in stellarators with quasi-symmetry.
Higgs Boson: god particle or divine comedy?
Rangacharyulu, Chary
2013-10-01
While particle physicists around the world rejoice the announcement of discovery of Higgs particle as a momentous event, it is also an opportune moment to assess the physicists' conception of nature. Particle theorists, in their ingenious efforts to unravel mysteries of the physical universe at a very fundamental level, resort to macroscopic many body theoretical methods of solid state physicists. Their efforts render the universe a superconductor of correlated quasi-particle pairs. Experimentalists, devoted to ascertain the elementary constituents and symmetries, depend heavily on numerical simulations based on those models and conform to theoretical slang in planning and interpretation of measurements . It is to the extent that the boundaries between theory/modeling and experiment are blurred. Is it possible that they are meandering in Dante's Inferno?
Motion behavior of particles in air-solid magnetically stabilized fluidized beds for separation
Institute of Scientific and Technical Information of China (English)
Song Shulei; Zhao Yuemin; Luo Zhenfu; Tang Ligang
2012-01-01
In order to study the settling mechanism of particles in an air-solid magnetically stabilized fluidized bed (MSFB) for separation,we carried out free settling and quasi-zero settling tests on the tracing particles.The results show that the main resistance forces as the tracing particles settled in an air-solid MSFB were motion resistance force and yield force.The motion resistance and yield forces greatly hindered the free settling of the particles by greatly decreasing the acceleration for settling process of the particles.The acceleration decreased from 3022.62 cm/s2 to zero in 0.1 s,and in the end,the particles stopped in the air-solid MSFB.The yield force on particles increased with increasing the magnetic field intensity,resulting in decrease of the quasi-zero settling displacement.However,the yield force on particles decreased with increasing the fluidized air velocity,leading to increase of the quasi-zero settling displacement.When the structure and operating parameters of the air-solid MSFB were set up,the yield stress on particles stopped in an air-solid MSFB was a function of diameter and density of particles.The settling displacements of equal diameter particles increased with increasing their densities,and the settling displacements of equal density particles increased with increasing their diameters.
Hunt, Arlon J.
1984-01-01
A method and apparatus whereby small carbon particles are made by pyrolysis of a mixture of acetylene carried in argon. The mixture is injected through a nozzle into a heated tube. A small amount of air is added to the mixture. In order to prevent carbon build-up at the nozzle, the nozzle tip is externally cooled. The tube is also elongated sufficiently to assure efficient pyrolysis at the desired flow rates. A key feature of the method is that the acetylene and argon, for example, are premixed in a dilute ratio, and such mixture is injected while cool to minimize the agglomeration of the particles, which produces carbon particles with desired optical properties for use as a solar radiant heat absorber.
The Properties of κ-quasi-*-A(n) Operator
Institute of Scientific and Technical Information of China (English)
ZUO Fei; SHEN Jun-li
2012-01-01
An operator T is called k-quasi-*-A(n) operator,if T*k|T1+n|2/1+nTk ≥T*k|T*|2Tk,k ∈ Z,which is a generalization of quasi-*-A(n) operator.In this paper we prove some properties of k-quasi-*-A(n) operator,such as,if T is a k-quasi-*-A(n) operator and N(T) (∈)N(T*),then its point spectrum and joint point spectrum are identical.Using these results,we also prove that if T is a k-quasi-*-A(n) operator and N(T) (∈) N(T*),then the spectral mapping theorem holds for the Weyl spectrum and for the essential approximate point spectrum.
Determining pitch-angle diffusion coefficients from test particle simulations
Ivascenko, A.; S. Lange; Spanier, F.; R. Vainio
2016-01-01
Transport and acceleration of charged particles in turbulent media is a topic of great interest in space physics and interstellar astrophysics. These processes are dominated by the scattering of particles off magnetic irregularities. The scattering process itself is usually described by small-angle scattering with the pitch-angle coefficient $D_{\\mu\\mu}$ playing a major role. Since the diffusion coefficient $D_{\\mu\\mu}$ can be determined analytically only for the approximation of quasi-linear...
Diffusion and particle mobility in 1D system
Borman, V. D.; Johansson, B.; Skorodumova, N. V.; Tronin, I. V.; Tronin, V. N.; Troyan, V. I.
2006-01-01
The transport properties of one-dimensional (1D) systems have been studied theoretically. Contradictory experimental results on molecular transport in quasi-1D systems, such as zeolite structures, when both diffusion transport acceleration and the existence of the diffusion mode with lower particle
Equations of motion for charged particles in strong laser fields
Ruhl, Hartmut
2016-01-01
Starting from the Dirac equation coupled to a classical radiation field a set of equations of motion for charged quasi-particles in the classical limit for slowly varying radiation and matter fields is derived. The radiation reaction term derived in the paper is the Abraham-Lorentz-Dirac term.
Closure relations for shallow granular flows from particle simulations
Weinhart, Thomas; Thornton, Anthony Richard; Luding, Stefan; Bokhove, Onno
The Discrete Particle Method (DPM) is used to model granular flows down an inclined chute. We observe three major regimes: static piles, steady uniform flows and accelerating flows. For flows over a smooth base, other (quasi-steady) regimes are observed where the flow is either highly energetic and
Martin, Brian R
2017-01-01
An accessible and carefully structured introduction to Particle Physics, including important coverage of the Higgs Boson and recent progress in neutrino physics. Fourth edition of this successful title in the Manchester Physics series. Includes information on recent key discoveries including : An account of the discovery of exotic hadrons, beyond the simple quark model; Expanded treatments of neutrino physics and CP violation in B-decays; An updated account of ‘physics beyond the standard model’, including the interaction of particle physics with cosmology; Additional problems in all chapters, with solutions to selected problems available on the book’s website; Advanced material appears in optional starred sections.
ION ACCELERATION AT THE QUASI-PARALLEL BOW SHOCK: DECODING THE SIGNATURE OF INJECTION
Energy Technology Data Exchange (ETDEWEB)
Sundberg, Torbjörn; Haynes, Christopher T.; Burgess, D. [School of Physics and Astronomy, Queen Mary University of London, London, E1 4NS (United Kingdom); Mazelle, Christian X. [IRAP, Université Paul Sabatier Toulouse III-CNRS, 31028 Toulouse Cedex 4 (France)
2016-03-20
Collisionless shocks are efficient particle accelerators. At Earth, ions with energies exceeding 100 keV are seen upstream of the bow shock when the magnetic geometry is quasi-parallel, and large-scale supernova remnant shocks can accelerate ions into cosmic-ray energies. This energization is attributed to diffusive shock acceleration; however, for this process to become active, the ions must first be sufficiently energized. How and where this initial acceleration takes place has been one of the key unresolved issues in shock acceleration theory. Using Cluster spacecraft observations, we study the signatures of ion reflection events in the turbulent transition layer upstream of the terrestrial bow shock, and with the support of a hybrid simulation of the shock, we show that these reflection signatures are characteristic of the first step in the ion injection process. These reflection events develop in particular in the region where the trailing edge of large-amplitude upstream waves intercept the local shock ramp and the upstream magnetic field changes from quasi-perpendicular to quasi-parallel. The dispersed ion velocity signature observed can be attributed to a rapid succession of ion reflections at this wave boundary. After the ions’ initial interaction with the shock, they flow upstream along the quasi-parallel magnetic field. Each subsequent wavefront in the upstream region will sweep the ions back toward the shock, where they gain energy with each transition between the upstream and the shock wave frames. Within three to five gyroperiods, some ions have gained enough parallel velocity to escape upstream, thus completing the injection process.
Thermodynamics of Quasi-One Oxides
Kuo, Yung-Kang
1995-11-01
Quasi-one-dimensional materials are of interest because of the large variety of phase transitions they exhibit, such as charge-density-wave (CDW), spin-density -wave (SDW), spin-Peierls (SP) and superconducting transitions. Thermodynamic measurements are important to our understanding of the nature and magnitude of the phase transitions and the effect of fluctuations. Two quasi-one-dimensional inorganic oxides are comprehensively investigated in this thesis. First, CuGeO _3 undergoes a spin-Peierls transition at 14 K, and second, K_{0.3}MoO _3 shows a charge-density-wave ground state below the transition temperature of 180 K. We measured the heat capacity of CuGeO _3, using a high resolution ac calorimeter, both in the absence and presence of magnetic field. For the zero-field data, a sharp discontinuity at its spin -Peierls phase transition (~14 K) is observed. The magnitude of the jump is consistent with mean-field theory, indicating a nearest neighbor exchange interaction ~75 K, and that low-dimensional fluctuations have a small effect in depressing T_{c}. A temperature -dependent activation energy is observed at very low temperature. Between 5 and 10 K, we observed an activation energy Delta ~ 24K ~ 1.76 T_{c}, suggesting that the gap opens up more quickly below T_{c} than predicted by mean-field theory. The ratio of the specific heat anomaly and temperature derivative of the magnetic susceptibility at T _{c} equals the observed value of rm d^2T_{c}/dH ^2 at T_{c}, as expected in mean-field theory, but this ratio deviates from mean-field behavior below the transition. The depression of T_{c } in the presence of a magnetic field agrees well with mean-field theory, and there are no signs of suppression and broadening of the specific heat peaks due to external magnetic fields. The activation energy appears to be temperature dependent in all fields, but there is no clear evidence of reducing the activation energy in higher fields, suggesting that there is no
Quasi-Hamiltonian description of classical spin
Matsyuk, Roman
2015-01-01
A family of Lagrange functions is considered, each producing the classical relativistic free spinning particle equation of motion of the third order. On this grounds a generalized Hamilton-Ostrohrads'kyj description of the free relativistic spherical top is proposed, which comply with the Pirani supplementary conditions.
Trapping, anomalous transport and quasi-coherent structures in magnetically confined plasmas
Vlad, Madalina
2009-01-01
Strong electrostatic turbulence in magnetically confined plasmas is characterized by trapping or eddying of particle trajectories produced by the $E\\times B$ stochastic drift. Trapping is shown to produce strong effects on test particles and on test modes. It determines non-standard statistics of trajectories: non-Gaussian distribution, memory effects and coherence. Trapped trajectories form quasi-coherent structure. Trajectory trapping has strong nonlinear effects on the test modes on turbulent plasmas. We determine the growth rate of drift modes as function of the statistical characteristics of the background turbulence. We show that trapping provides the physical mechanism for the inverse cascade observed in drift turbulence and for the zonal flow generation.
Nonlinear Mirror and Weibel modes: peculiarities of quasi-linear dynamics
Directory of Open Access Journals (Sweden)
O. A. Pokhotelov
2010-12-01
Full Text Available A theory for nonlinear evolution of the mirror modes near the instability threshold is developed. It is shown that during initial stage the major instability saturation is provided by the flattening of the velocity distribution function in the vicinity of small parallel ion velocities. The relaxation scenario in this case is accompanied by rapid attenuation of resonant particle interaction which is replaced by a weaker adiabatic interaction with mirror modes. The saturated plasma state can be considered as a magnetic counterpart to electrostatic BGK modes. After quasi-linear saturation a further nonlinear scenario is controlled by the mode coupling effects and nonlinear variation of the ion Larmor radius. Our analytical model is verified by relevant numerical simulations. Test particle and PIC simulations indeed show that it is a modification of distribution function at small parallel velocities that results in fading away of free energy driving the mirror mode. The similarity with resonant Weibel instability is discussed.
Motility of Escherichia coli in a quasi-two-dimensional porous medium
Sosa-Hernández, Juan Eduardo; Santillán, Moisés; Santana-Solano, Jesús
2017-03-01
Bacterial migration through confined spaces is critical for several phenomena, such as biofilm formation, bacterial transport in soils, and bacterial therapy against cancer. In the present work, E. coli (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-two-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98-μ m -diameter spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing several trajectory parameters (instantaneous velocity, turn angle, mean squared displacement, etc.), and contrasting with the results of a random-walk model developed ad hoc, we were able to quantify the effects that different obstacle concentrations have upon bacterial motility.
Particle-laden turbulence under radiation: toward a novel small-particle solar receiver
Frankel, Ari; Mani, Ali; Iaccarino, Gianluca
2016-11-01
In particle-based solar receivers, an array of mirrors focuses sunlight onto a falling curtain of particles in a duct that absorb the light and warm up. The heated particles can be stored for later energy extraction. In this work we consider a design concept in which the particles and air are in a co-flowing configuration, and as the particles are heated they conduct the energy to the surrounding air. The air-particle mixture can then be separated and the heated air used for energy extraction. To assess the viability of this energy concept we have developed a simulation capability to analyze the flow of small particles in a turbulent flow with radiation. The code combines a point-particle direct numerical simulation of the particle-air flow in the low Mach number limit with the discrete ordinates solution of the gray, quasi-steady radiative transfer equation. We will describe the individual solution components and the coupling methodology. We will then demonstrate some results from the replication of a lab-scale experiment of a laser diode array irradiating a transparent channel with a flowing air-particle mixture. This work was supported by the Predictive Science Academic Alliance Program 2 at Stanford.
Resonant and non-resonant whistlers-particle interaction in the radiation belts
Camporeale, E.
2015-01-01
We study the wave-particle interactions between lower band chorus whistlers and an anisotropic tenuous population of relativistic electrons. We present the first direct comparison of first-principle Particle-in-Cell (PIC) simulations with a quasi-linear diffusion code. In the PIC approach, the waves
Resonant and non-resonant whistlers-particle interaction in the radiation belts
Camporeale, E.
2014-01-01
We study the wave-particle interactions between lower band chorus whistlers and an anisotropic tenuous population of relativistic electrons. We present the first direct comparison of first-principle Particle-in-Cell (PIC) simulations with a quasi-linear diffusion code, in this context. In the PIC ap
A Quasi-Decoupled State for Dark Matter in Non-Standard Thermal Histories
Waldstein, Isaac Raj; Ilie, Cosmin
2016-01-01
In a radiation-dominated universe, dark matter kinetically decouples from Standard Model particles when the momentum-transfer rate equals the expansion rate. However, dark matter may kinetically decouple during an early matter-dominated era (EMDE), which occurs when the energy content of the Universe is dominated by either an oscillating scalar field or a semi-stable massive particle before Big Bang Nucleosynthesis. Until now, it has been assumed that kinetic decoupling during an EMDE happens similarly to the way it does in a radiation-dominated era. We show that this is not the case. By studying the evolution of the dark matter temperature, we establish a quasi-decoupled state for dark matter in an EMDE, during which the dark matter temperature cools faster than the plasma temperature but slower than it would if the dark matter were fully decoupled. The dark matter does not fully decouple until the EMDE ends and the Universe becomes radiation dominated. We also extend the criteria for quasi-decoupling to oth...
Quasi-mosaicity as a powerful tool to investigate coherent effects
Bellucci, Valerio; Camattari, Riccardo; Guidi, Vincenzo
2013-09-01
Quasi-mosaicity is a mechanical property driven by anisotropy in diamond-like structure crystals such as Si and Ge. QM crystals were recently proposed as optical components of a Laue lens for focusing hard X-rays (with energy larger than 70 keV). In contrast to a Laue lens based on conventional crystals (e.g. mosaic crystals), usage of QM crystals allows focusing the incident beam in a spot smaller than the dimension of the diffracting crystal. Focusing of photons in a small spot would allow an unprecedented resolution and sensitivity, together with a wide-passband response. In astrophysics, a Laue lens implementing QM crystals should allow observations of cosmic phenomena producing X-ray emissions with high sensitivity. As another, a Laue lens would be useful for imaging in nuclear medicine, leading to a lower radioactive dose imparted to the patient because of no need for tomography scanning. Quasi-mosaicity was also used for bending Si crystals in order to steer high-energy particles via coherent effects in crystals, viz. planar channeling and volume reflection. Channeled or reflected light particles are also useful as sources of gamma ray beams with intense flux, which can be either monochromatic or polychromatic.
Quasi-satellite dynamics in formation flight
Mikkola, Seppo
2016-01-01
The quasi-satellite (QS) phenomenon makes two celestial bodies to fly near each other (Mikkola et al. 2006) and that effect can be used also to make artificial satellites move in tandem. We consider formation flight of two or three satellites in low eccentricity near Earth orbits. With the help of weak ion thrusters it is possible to accomplish tandem flight. With ion thrusters it is also possible to mimic many kinds of mutual force laws between the satellites. We found that both a constant repulsive force or an attractive force that decreases with the distance are able to preserve the formation in which the eccentricities cause the actual relative motion and the weak thrusters keep the mean longitude difference small. Initial values are important for the formation flight but very exact adjustment of orbital elements is not important. Simplicity is one of our goals in this study and this result is achieved at least in the way that, when constant force thrusters are used, the satellites only need to detect the...
Large-Scale Quasi-geostrophic Magnetohydrodynamics
Balk, Alexander M.
2014-12-01
We consider the ideal magnetohydrodynamics (MHD) of a shallow fluid layer on a rapidly rotating planet or star. The presence of a background toroidal magnetic field is assumed, and the "shallow water" beta-plane approximation is used. We derive a single equation for the slow large length scale dynamics. The range of validity of this equation fits the MHD of the lighter fluid at the top of Earth's outer core. The form of this equation is similar to the quasi-geostrophic (Q-G) equation (for usual ocean or atmosphere), but the parameters are essentially different. Our equation also implies the inverse cascade; but contrary to the usual Q-G situation, the energy cascades to smaller length scales, while the enstrophy cascades to the larger scales. We find the Kolmogorov-type spectrum for the inverse cascade. The spectrum indicates the energy accumulation in larger scales. In addition to the energy and enstrophy, the obtained equation possesses an extra (adiabatic-type) invariant. Its presence implies energy accumulation in the 30° sector around zonal direction. With some special energy input, the extra invariant can lead to the accumulation of energy in zonal magnetic field; this happens if the input of the extra invariant is small, while the energy input is considerable.
Large Scale Quasi-geostrophic Magnetohydrodynamics
Balk, Alexander M
2014-01-01
We consider the ideal magnetohydrodynamics (MHD) of a shallow fluid layer on a rapidly rotating planet or star. The presence of a background toroidal magnetic field is assumed, and the "shallow water" beta-plane approximation is used. We derive a single equation for the slow large length scale dynamics. The range of validity of this equation fits the MHD of the lighter fluid at the top of Earth's outer core. The form of this equation is similar to the quasi-geostrophic (Q-G) equation (for usual ocean or atmosphere), but the parameters are essentially different. Our equation also implies the inverse cascade; but contrary to the usual Q-G situation, the energy cascades to smaller length scales, while the enstrophy cascades to the larger scales. We find the Kolmogorov-type spectrum for the inverse cascade. The spectrum indicates the energy accumulation in larger scales. In addition to the energy and enstrophy, the obtained equation possesses an extra invariant. Its presence is shown to imply energy accumulation ...
The Causes of Quasi-homologous CMEs
Liu, Lijuan; Wang, Yuming; Liu, Rui; Zhou, Zhenjun; Temmer, M.; Thalmann, J. K.; Liu, Jiajia; Liu, Kai; Shen, Chenglong; Zhang, Quanhao; Veronig, A. M.
2017-08-01
In this paper, we identified the magnetic source locations of 142 quasi-homologous (QH) coronal mass ejections (CMEs), of which 121 are from solar cycle (SC) 23 and 21 from SC 24. Among those CMEs, 63% originated from the same source location as their predecessor (defined as S-type), while 37% originated from a different location within the same active region as their predecessor (defined as D-type). Their distinctly different waiting time distributions, peaking around 7.5 and 1.5 hr for S- and D-type CMEs, suggest that they might involve different physical mechanisms with different characteristic timescales. Through detailed analysis based on nonlinear force-free coronal magnetic field modeling of two exemplary cases, we propose that the S-type QH CMES might involve a recurring energy release process from the same source location (by magnetic free energy replenishment), whereas the D-type QH CMEs can happen when a flux tube system is disturbed by a nearby CME.
Quasi Goldstone fermion as a sterile neutrino
Energy Technology Data Exchange (ETDEWEB)
Jin Chun, E. [International Center for Theoretical Physics, P.O. Box 586, 34100 Trieste (Italy); Joshipura, A.S. [Theoretical Physics Group, Physical Research Laboratory, Navarangpura, Ahmedabad, 380 009 (India); Smirnov, A.Y. [International Center for Theoretical Physics P.O. Box 586, 34100 Trieste (Italy)]|[Institute for Nuclear Research, Russian Academy of Sciences, 117312 Moscow (Russia)
1996-10-01
The existence of sterile neutrinos is hinted by the simultaneous presence of diverse neutrino anomalies. We suggest that the quasi Goldstone fermions (QGF{close_quote}s) arising in supersymmetric theory as a result of spontaneous breaking of global symmetry such as the Peccei-Quinn symmetry or the lepton number symmetry can play the role of the sterile neutrino. The smallness of the mass of QGF{close_quote}s ({ital m}{sub {ital S}}{approximately}10{sup {minus}3}{endash}10 eV) can be related to the specific choice of superpotential or K{umlt a}hler potential (e.g., no-scale kinetic terms for certain superfields). Mixing of QGF{close_quote}s with neutrinos implies {ital R}-parity violation. It can proceed via the coupling of QGF{close_quote}s with Higgs supermultiplets or directly with a lepton doublet. A model which accounts for the solar and atmospheric anomalies and dark matter is presented. {copyright} {ital 1996 The American Physical Society.}
Computational and Experimental Study of Spherocylinder Particles in Fluidized Beds
Mahajan, Vinay; Kuipers, Hans; Padding, Johan; Multiphase Reactors Group, TU Eindhoven Team
2016-11-01
Non-spherical particle flows are often encountered in fluidized process equipment. A coupled computational fluid dynamics (CFD) and discrete element method(DEM) approach has been extensively applied in recent years to study these flows at the particle scale. However, most of these studies focus on spherical particles while in reality, the constituent particles are seldom spherical. Particle shape can significantly affect the hydrodynamical response in fluidized beds. The drag force acting on a non-spherical particle can vary considerably with particle shape, orientation of the particle, Reynolds number and packing fraction. In this work, a CFD-DEM approach has been extended to model a lab scale quasi-2D fluidized bed of spherocylinder (rod-like) particles. These particles can be classified as Geldart D particles and have an aspect ratio of 4. Numerical results for the pressure drop, bed height and solid circulation patterns are compared with results from a complementary laboratory experiment. We also present results on particle orientations close to the confining walls, which provides interesting insight regarding the particle alignment. Thus the capability of the CFD-DEM approach to efficiently account for global bed dynamics in fluidized bed of rod-like particle is demonstrated. This research work is funded by ERC Grant.
Quasi-periodic solutions for an asymmetric oscillation
Huang, Peng; Li, Xiong; Liu, Bin
2016-10-01
In this paper we study the dynamical behaviour of the differential equation x‧‧+ax+-bx-=f(t), where {{x}+}=\\max ≤ft\\{x,0\\right\\} , {{x}-}=\\max ≤ft\\{-x,0\\right\\} , a and b are two different positive constants, and f (t) is a smooth quasi-periodic function. For this purpose, firstly, we have to establish some variants of the invariant curve theorem of planar smooth quasi-periodic mappings, which was proved recently by the authors (see Huang et al preprint). Then we will discuss the boundedness of all solutions and the existence of quasi-periodic solutions for the above asymmetric oscillation.
Affine and quasi-affine frames for rational dilations
DEFF Research Database (Denmark)
Bownik, Marcin; Lemvig, Jakob
2011-01-01
, the corresponding family of quasi-affine systems are frames with uniform frame bounds. We also prove a similar equivalence result between pairs of dual affine frames and dual quasi-affine frames. Finally, we uncover some fundamental differences between the integer and rational settings by exhibiting an example......In this paper we extend the investigation of quasi-affine systems, which were originally introduced by Ron and Shen [J. Funct. Anal. 148 (1997), 408-447] for integer, expansive dilations, to the class of rational, expansive dilations. We show that an affine system is a frame if, and only if...
Concept of quasi-periodic undulator - control of radiation spectrum
Energy Technology Data Exchange (ETDEWEB)
Sasaki, Shigemi [Japan Atomic Energy Research Institute, Ibaraki (Japan)
1995-02-01
A new type of undulator, the quasi-periodic undulator (QPU) is considered which generates the irrational harmonics in the radiation spectrum. This undulator consists of the arrays of magnet blocks aligned in a quasi-periodic order, and consequentially lead to a quasi-periodic motion of electron. A combination of the QPU and a conventional crystal/grating monochromator provides pure monochromatic photon beam for synchrotron radiation users because the irrational harmonics do not be diffracted in the same direction by a monochromator. The radiation power and width of each radiation peak emitted from this undulator are expected to be comparable with those of the conventional periodic undulator.
Quasi-lisse vertex algebras and modular linear differential equations
Arakawa, Tomoyuki
2016-01-01
We introduce a notion of quasi-lisse vertex algebras, which generalizes admissible affine vertex algebras. We show that the normalized character of an ordinary module over a quasi-lisse vertex operator algebra has a modular invariance property, in the sense that it satisfies a modular linear differential equation. As an application we obtain the explicit character formulas of simple affine vertex algebras associated with the Deligne exceptional series at level $-h^{\\vee}/6-1$, which expresses the homogeneous Schur limit of the superconformal index of 4d SCFTs studied by Beem, Lemos, Liendo, Peelaers, Rastelli and van Rees, as quasi-modular forms.
Stiffness of serial and quasi-serial manipulators: comparison analysis
Directory of Open Access Journals (Sweden)
Klimchik Alexandr
2016-01-01
Full Text Available The paper deals with comparison analysis of serial and quasi-serial manipulators. It shows a difference between stiffness behaviours of corresponding industrial robots under external loading, which is caused by machining process. The analysis is based on the estimation of compliance errors induced by cutting forces that are applied to the manipulator end-effector. We demonstrate that the quasi-seral manipulators are preferable for large-dimensional tasks while the quasi-serial ones better suit small size tasks.
Conformally warped manifolds, quasi-Einstein metrics, and tractors
Case, Jeffrey S
2011-01-01
We present a natural formulation of CWMs in the language of tractor bundles from conformal geometry. In particular, this gives rise to a correspondence between quasi-Einstein metrics and parallel sections of certain tractor bundles. We use this formulation to give a sharp upper bound on the dimension of the vector space of quasi-Einstein metrics, providing a different perspective on some recent results of He, Petersen and Wylie. We also use this formulation to mention some potentially interesting connections between conformal geometry, the study of quasi-Einstein metrics, and gradient Ricci solitons.
Quasi-periodicity in the autonomous glycolytic system
Institute of Scientific and Technical Information of China (English)
GAO Qingyu; ZHANG Lu; ZHANG Xing; WANG Jichang
2005-01-01
This study predicts that quasi-periodic oscilla-tions could exist in a detailed model of glycolysis that is ana-lyzed in an autonomous system. In addition to period-dou- bling, quasi-periodic and period-adding bifurcation, a new stationary branch, which lies in between the thermodynamic and flow branches, is also uncovered in the glycolytic reac-tion system. Results presented in this study illustrate that the Michaelis constant (K4GAP) of glyceraldehyde 3-phosphate dehydrogenase for glyceraldehyde 3-phosphate has great influences on glycolytic oscillations, in which increasing K4GAP widens the range of flow rate over which quasi-peri- odic oscillations exist.
The Quasi-Exactly Solvable Problems in Relativistic Quantum Mechanics
Liu, Li-Yan; Hao, Qing-Hai
2014-06-01
We study the quasi-exactly solvable problems in relativistic quantum mechanics. We consider the problems for the two-dimensional Klein—Gordon and Dirac equations with equal vector and scalar potentials, and try to find the general form of the quasi-exactly solvable potential. After obtaining the general form of the potential, we present several examples to give the specific forms. In the examples, we show for special parameters the harmonic potential plus Coulomb potential, Killingbeck potential and a quartic potential plus Cornell potential are quasi-exactly solvable potentials.
Quasi-elastic neutron scattering studies of protein dynamics
Energy Technology Data Exchange (ETDEWEB)
Rorschach, H.E.
1993-05-25
Results that shed new light on the study of protein dynamics were obtained by quasi-elastic neutron scattering. The triple axis instrument H-9 supplied by the cold source was used to perform a detailed study of the quasi-elastic spectrum and the Debye-Waller factor for trypsin in powder form, in solution, and in crystals. A preliminary study of myoglobin crystals was also done. A new way to view the results of quasi-elastic scattering experiments is sketched, and the data on trypsin are presented and analyze according to this new picture.
QUASI-STATIC ANALYSIS FOR VISCOELASTIC TIMOSHENKO BEAMS WITH DAMAGE
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Based on convolution-type constitutive equations for linear viscoelastic materials with damage and the hypotheses of Timoshenko beams, the equations governing quasi-static and dynamical behavior of Timoshenko beams with damage were first derived. The quasi-static behavior of the viscoelastic Timoshenko beam under step loading was analyzed and the analytical solution was obtained in the Laplace transformation domain. The deflection and damage curves at different time were obtained by using the numerical inverse transform and the influences of material parameters on the quasi-static behavior of the beam were investigated in detail.
Quasi-optimal convergence rate of an AFEM for quasi-linear problems
Garau, Eduardo M.; Morin, Pedro; Zuppa, Carlos
2010-01-01
We prove the quasi-optimal convergence of a standard adaptive finite element method (AFEM) for nonlinear elliptic second-order equations of monotone type. The adaptive algorithm is based on residual-type a posteriori error estimators and D\\"orfler's strategy is assumed for marking. We first prove a contraction property for a suitable definition of total error, which is equivalent to the total error as defined by Casc\\'on et al. (in SIAM J. Numer. Anal. 46 (2008), 2524--2550), and implies line...
Solutions to the Quasi-flatness and Quasi-lambda Problems
Barrow, John D; Barrow, John D.; Magueijo, Joao
1999-01-01
Big Bang models of the Universe predict rapid domination by curvature, a paradox known as the flatness problem. Solutions to this problem usually leave the Universe exactly flat for every practical purpose. Explaining a nearly but not exactly flat current Universe is a new problem, which we label the quasi-flatness problem. We show how theories incorporating time-varying coupling constants could drive the Universe to a late-time near-flat attractor. A similar problem may be posed with regards to the cosmological constant as well.
Kennedy, Eugene
2012-01-01
Stimulated by the Large Hadron Collider and the search for the elusive Higgs Boson, interest in particle physics continues at a high level among scientists and the general public. This book includes theoretical aspects, with chapters outlining the generation model and a charged Higgs boson model as alternative scenarios to the Standard Model. An introduction is provided to postulated axion photon interactions and associated photon dispersion in magnetized media. The complexity of particle physics research requiring the synergistic combination of theory, hardware and computation is described in terms of the e-science paradigm. The book concludes with a chapter tackling potential radiation hazards associated with extremely weakly interacting neutrinos if produced in copious amounts with future high-energy muon-collider facilities.
Degond, Pierre; Tadmor, Eitan
2017-01-01
This volume collects ten surveys on the modeling, simulation, and applications of active particles using methods ranging from mathematical kinetic theory to nonequilibrium statistical mechanics. The contributing authors are leading experts working in this challenging field, and each of their chapters provides a review of the most recent results in their areas and looks ahead to future research directions. The approaches to studying active matter are presented here from many different perspectives, such as individual-based models, evolutionary games, Brownian motion, and continuum theories, as well as various combinations of these. Applications covered include biological network formation and network theory; opinion formation and social systems; control theory of sparse systems; theory and applications of mean field games; population learning; dynamics of flocking systems; vehicular traffic flow; and stochastic particles and mean field approximation. Mathematicians and other members of the scientific commu...
Krauss, Lawrence M
1997-01-01
Astrophysics and cosmology provide fundamental testing grounds for many ideas in elementary particle physics, and include potential probes which are well beyond the range of current or even planned accelerators. In this series of 3 lectures, I will give and overview of existing constraints, and a discussion of the potential for the future. I will attempt whenever possible to demonstrate the connection between accelerator-based physics and astrophysicas/cosmology. The format of the kectures will be to examine observables from astrophysics, and explore how these can be used to constrain particle physics. Tentatively, lecture 1 will focus on the age and mass density of the universe and galaxy. Lecture 2 will focus on stars, stellar evolution, and the abundance of light elements. Lecture 3 will focus on various cosmic diffuse backgrounds, including possibly matter, photons, neutrinos and gravitational waves.
Sun, Xiaobin
2000-01-01
Several engineering processes are powder based, ranging from food processing to engineering ceramic and composite production. In most of these processes, powders of different composition are mixed together in order to produce the final product, and this combining of powders of different density, shape, and surface properties is often very difficult. Mixtures may be quite inhomogeneous. This research focuses on a method of avoiding such problems, by coating individual particles of one material...
2008-01-01
This image of Martian soil was taken by the Phoenix Lander's atomic force microscope on Sol 74 of the mission, which began on May 25, 2008. This image of a flat, smooth-surfaced particle is consistent with the appearance of soil from Earth containing the mineral phyllosilicate. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by JPL, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.
Williams, Paul; Read, Peter; Haine, Thomas
2010-05-01
We compare laboratory observations of equilibrated baroclinic waves in the rotating two-layer annulus, with numerical simulations from a quasi-geostrophic model. The laboratory experiments lie well outside the quasi-geostrophic regime: the Rossby number reaches unity; the depth-to-width aspect ratio is large; and the fluid contains ageostrophic inertia-gravity waves. Despite being formally inapplicable, the quasi-geostrophic model captures the laboratory flows reasonably well. The model displays several systematic biases, which are consequences of its treatment of boundary layers and neglect of interfacial surface tension, and which may be explained without invoking the dynamical effects of the moderate Rossby number, large aspect ratio or inertia-gravity waves. We conclude that quasi-geostrophic theory appears to continue to apply well outside its formal bounds. This is an unexpected and intriguing result that could not have been predicted from the existing literature. It is also potentially useful, for example by permitting the use of a low-order quasi-geostrophic model to easily map out the bifurcation structure - which would be very difficult with a primitive equations model - followed by the use of a primitive equations model for more quantitative agreement in specific cases. Reference Williams, PD, PL Read and TWN Haine (2010) Testing the limits of quasi-geostrophic theory: application to observed laboratory flows outside the quasi-geostrophic regime. Journal of Fluid Mechanics, in press.
Quasi-isochronous muon collection channels
Energy Technology Data Exchange (ETDEWEB)
Ankenbrandt, Charles M. [Muons, Inc., Batavia, IL (United States); Neuffer, David [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Johnson, Rolland P. [Muons, Inc., Batavia, IL (United States)
2015-04-26
Intense muon beams have many potential commercial and scientific applications, ranging from low-energy investigations of the basic properties of matter using spin resonance to large energy-frontier muon colliders. However, muons originate from a tertiary process that produces a diffuse swarm. To make useful beams, the swarm must be rapidly captured and cooled before the muons decay. In this STTR project a promising new concept for the collection and cooling of muon beams to increase their intensity and reduce their emittances was investigated, namely, the use of a nearly isochronous helical cooling channel (HCC) to facilitate capture of the muons into RF bunches. The muon beam can then be cooled quickly and coalesced efficiently to optimize the luminosity of a muon collider, or could provide compressed muon beams for other applications. Optimal ways to integrate such a subsystem into the rest of a muon collection and cooling system, for collider and other applications, were developed by analysis and simulation. The application of quasi-isochronous helical cooling channels (QIHCC) for RF capture of muon beams was developed. Innovative design concepts for a channel incorporating straight solenoids, a matching section, and an HCC, including RF and absorber, were developed, and its subsystems were simulated. Additionally, a procedure that uses an HCC to combine bunches for a muon collider was invented and simulated. Difficult design aspects such as matching sections between subsystems and intensity-dependent effects were addressed. The bunch recombination procedure was developed into a complete design with 3-D simulations. Bright muon beams are needed for many commercial and scientific reasons. Potential commercial applications include low-dose radiography, muon catalyzed fusion, and the use of muon beams to screen cargo containers for homeland security. Scientific uses include low energy beams for rare process searches, muon spin resonance applications, muon beams for
SHERLOCK: A quasi-model-independent new physics search strategy.
Knuteson, Bruce
2000-04-01
We develop a quasi-model-independent prescription for searching for physics responsible for the electroweak symmetry breaking in the Standard Model, and show a preliminary version of what we find when this prescription is applied to the DZero data.
Differential subordination for meromorphic multivalent quasi-convex functions
R. W. Ibrahim; M. Darus
2010-01-01
We introduce new classes of meromorphic multivalent quasi-convex functions and find some sufficient differential subordination theorems for such classes in punctured unit disk with applications in fractional calculus.
Total variation approximation for quasi-equilibrium distributions, II
Barbour, A D
2011-01-01
Quasi-stationary distributions, as discussed by Darroch & Seneta (1965), have been used in biology to describe the steady state behaviour of population models which, while eventually certain to become extinct, nevertheless maintain an apparent stochastic equilibrium for long periods. These distributions have some drawbacks: they need not exist, nor be unique, and their calculation can present problems. In an earlier paper, we gave biologically plausible conditions under which the quasi-stationary distribution is unique, and can be closely approximated by distributions that are simple to compute. In this paper, we consider conditions under which the quasi-stationary distribution, if it exists, need not be unique, but an apparent stochastic equilibrium can nonetheless be identified and computed; we call such a distribution a quasi-equilibrium distribution.
Differential subordination for meromorphic multivalent quasi-convex functions
Directory of Open Access Journals (Sweden)
R. W. Ibrahim
2010-02-01
Full Text Available We introduce new classes of meromorphic multivalent quasi-convex functions and find some sufficient differential subordination theorems for such classes in punctured unit disk with applications in fractional calculus.
Weak-quasi-bandwidth and forward-bandwidth of graphs
Institute of Scientific and Technical Information of China (English)
原晋江
1996-01-01
Concepts of weak-quasi-bandwidth and forward-bandwidth of graphs are introduced. They are used to studythe following problems in graph theory: bandwidth, topological bandwidth, fill-in, profile, path-width, tree-width.
Improved quasi parton distribution through Wilson line renormalization
Chen, Jiunn-Wei; Zhang, Jian-Hui
2016-01-01
Recent developments showed that hadron light-cone parton distributions could be directly extracted from spacelike correlators, known as quasi parton distributions, in the large hadron momentum limit. Unlike the normal light-cone parton distribution, a quasi parton distribution contains ultraviolet (UV) power divergence associated with the Wilson line self energy. We show that to all orders in the coupling expansion, the power divergence can be removed by a "mass" counterterm in the auxiliary $z$-field formalism, in the same way as the renormalization of power divergence for an open Wilson line. After adding this counterterm, the quasi quark distribution is improved such that it contains at most logarithmic divergences. Based on a simple version of discretized gauge action, we present the one-loop matching kernel between the improved non-singlet quasi quark distribution with a lattice regulator and the corresponding quark distribution in dimensional regularization.
Dynamical Equation of Post Newtonian Quasi-rigid Body
Institute of Scientific and Technical Information of China (English)
XU Chong-Ming; TAO Jin-He; HUANG Tian-Yi; WU Xue-Jun
2004-01-01
We derive the dynamical equation ofa post Newtonian (PN) quasi-rigid body from the general rotational equation of motion, I.e. The PN rotational equation of motion for a quasi-rigid body. It is emphasized that a rotational angular velocity vector and a figure axis besides the first post Newtonian (1PN) spin vector can be defined and realized for the model of a PN quasi-rigid body model constructed recently. Actually, we have shown that the moment of inertia tensor of a quasi-rigid body can be transformed into a diagonal form by an orthogonal transformation, which defines the principal axes of inertia of the body. As an example, its torque-free motion is discussed and a PN Poinsot configuration, which is similar to the Newtonian one with a small 1PN correction, is solved.
Quasi-Bézier Curves with Shape Parameters
Directory of Open Access Journals (Sweden)
Jun Chen
2013-01-01
Full Text Available The universal form of univariate Quasi-Bézier basis functions with multiple shape parameters and a series of corresponding Quasi-Bézier curves were constructed step-by-step in this paper, using the method of undetermined coefficients. The series of Quasi-Bézier curves had geometric and affine invariability, convex hull property, symmetry, interpolation at the endpoints and tangent edges at the endpoints, and shape adjustability while maintaining the control points. Various existing Quasi-Bézier curves became special cases in the series. The obvious geometric significance of shape parameters made the adjustment of the geometrical shape easier for the designer. The numerical examples indicated that the algorithm was valid and can easily be applied.
Infinitesimal generators and quasi-units in potential theory.
Arsove, M; Leutwiler, H
1975-07-01
The underlying structure is taken as a strongly superharmonic cone [unk], defined as a partially ordered abelian semigroup with identity 0 which admits a multiplication by nonnegative scalars and satisfies two fundamental axioms of a potentialtheoretic character. In terms of a fixed nonzero element e there is introduced on [unk] a one-parameter family of nonlinear operators S(lambda) (lambda >/= 0) closely connected with the abstract theory of quasibounded and singular elements. The semigroup {S(lambda)} admits an infinitesimal generator A, and the elements invariant under A, called quasi-units, generalize the Yosida quasi-units in the theory of Riesz spaces. Quasi-units in [unk] are studied, both from a potentialtheoretic and a function-alanalytic viewpoint, culminating in a spectral representation theorem for quasi-bounded elements which extends the classical Freudenthal spectral theorem of Riesz space theory.
Log canonical thresholds of quasi-ordinary hypersurface singularities
Budur, Nero; Villa, Manuel González
2011-01-01
The log canonical thresholds of irreducible quasi-ordinary hypersurface singularities are computed, using an explicit list of pole candidates for the motivic zeta function found by the last two authors.
Studies of nondegenerate, quasi-phase-matched optical parametric amplification
Energy Technology Data Exchange (ETDEWEB)
Lawrence Livermore National Laboratory
2004-03-18
We have performed extensive numerical studies of quasi-phase-matched optical parametric amplification with the aim to improve its nondegenerate spectral bandwidth. Our multi-section fan-out design calculations indicate a 35-fold increase in spectral bandwidth.
Improved quasi parton distribution through Wilson line renormalization
Directory of Open Access Journals (Sweden)
Jiunn-Wei Chen
2017-02-01
Full Text Available Recent developments showed that hadron light-cone parton distributions could be directly extracted from spacelike correlators, known as quasi parton distributions, in the large hadron momentum limit. Unlike the normal light-cone parton distribution, a quasi parton distribution contains ultraviolet (UV power divergence associated with the Wilson line self energy. We show that to all orders in the coupling expansion, the power divergence can be removed by a “mass” counterterm in the auxiliary z-field formalism, in the same way as the renormalization of power divergence for an open Wilson line. After adding this counterterm, the quasi quark distribution is improved such that it contains at most logarithmic divergences. Based on a simple version of discretized gauge action, we present the one-loop matching kernel between the improved non-singlet quasi quark distribution with a lattice regulator and the corresponding quark distribution in dimensional regularization.
Optimization: NURBS and the quasi-Newton method
Coburn, Todd Dale
Optimization is important in both engineering and mathematics. The Quasi-Newton Method is widely used for optimization due to its speed and efficiency. NonUniform Rational B-Splines (NURBS) are piecewise parametric approximations to curves and surfaces. NURBS have great curve-fitting properties that can be applied to improve optimization performance. This dissertation investigated the use of NURBS in optimization, focusing primarily on the coupling of NURBS with the Quasi-Newton Method. A hybrid optimization procedure dubbed the NURBS-Quasi-Newton (NQN) Method was developed and utilized that can virtually assure that the global minimum will be found. A Method was also developed to implement Pure NURBS Optimization (PNO), which can be used to optimize non-continuous and singular functions as well as functions of point cloud data. It was concluded that NURBS offer significant benefits for optimization, both individually and coupled with Quasi-Newton Methods.
Generalization of quasi-exactly solvable and isospectral potentials
Indian Academy of Sciences (India)
P K Bera; J Datta; M M Panja; Tapas Sil
2007-09-01
A uniﬁed approach in the light of supersymmetric quantum mechanics (SSQM) has been suggested for generating multidimensional quasi-exactly solvable (QES) potentials. This method provides a convenient means to construct isospectral potentials of derived potentials.
The microphysical properties of small ice particles measured during MACPEX
Schmitt, C. G.; Schnaiter, M.; Heymsfield, A.; Bansemer, A.; Hirst, E.
2012-12-01
During the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) field campaign, the Small Ice Detector version 3 (SID-3) and the NCAR Video Ice Particle Sampler (VIPS) probes were operated onboard the NASA WB-57 aircraft to measure the microphysical properties of small ice particles in midlatitude cirrus clouds. The VIPS was optimized to measure the particle size distribution and projected area properties of ice particles between 20 and 200 microns and measurements agreed well with other microphysical probes. SID-3 measures the forward light scattering pattern from ice particles in the 1 to 100 micron size range. Forward scattering patterns can be used to characterize ice particle shape as well as surface roughness. Scattering patterns appear to be 'speckled' when particles have surface roughness and/or are polycrystalline. Scattering patterns can be used to identify quasi-spherical ice particles as well as particles which are sublimating. Sublimating crystals, spherical ice particles, and particles with surface roughness were all observed by SID-3 during MACPEX. Observed particle properties will be correlated to concurrent atmospheric observations. Measurements from the controlled environment of the Aerosol Interaction and Dynamics in the Atmosphere (AIDA) cloud chamber will be related to atmospheric particle measurements.
Modelling the solar wind interaction with Mercury by a quasi-neutral hybrid model
Directory of Open Access Journals (Sweden)
E. Kallio
Full Text Available Quasi-neutral hybrid model is a self-consistent modelling approach that includes positively charged particles and an electron fluid. The approach has received an increasing interest in space plasma physics research because it makes it possible to study several plasma physical processes that are difficult or impossible to model by self-consistent fluid models, such as the effects associated with the ions’ finite gyroradius, the velocity difference between different ion species, or the non-Maxwellian velocity distribution function. By now quasi-neutral hybrid models have been used to study the solar wind interaction with the non-magnetised Solar System bodies of Mars, Venus, Titan and comets. Localized, two-dimensional hybrid model runs have also been made to study terrestrial dayside magnetosheath. However, the Hermean plasma environment has not yet been analysed by a global quasi-neutral hybrid model.
In this paper we present a new quasi-neutral hybrid model developed to study various processes associated with the Mercury-solar wind interaction. Emphasis is placed on addressing advantages and disadvantages of the approach to study different plasma physical processes near the planet. The basic assumptions of the approach and the algorithms used in the new model are thoroughly presented. Finally, some of the first three-dimensional hybrid model runs made for Mercury are presented.
The resulting macroscopic plasma parameters and the morphology of the magnetic field demonstrate the applicability of the new approach to study the Mercury-solar wind interaction globally. In addition, the real advantage of the kinetic hybrid model approach is to study the property of individual ions, and the study clearly demonstrates the large potential of the approach to address these more detailed issues by a quasi-neutral hybrid model in the future.
Key words. Magnetospheric physics
Strange Quasi-Repeller in a Kicked Rotor
Institute of Scientific and Technical Information of China (English)
姜玉梅; 何大韧
2003-01-01
A new kind of crisis was observed in a system where a transition from conservative toquasi-dissipative can be observed. The crisis signifies a sudden and intrinsic change of a stochasticweb, which is formed by the end-results of the images of the discontinuous borderlines of the systemfunction. In the crisis, a strange quasi-repeller can be defined. When changing the controllingparameter, the variation of the fractile dimension of the quasi-repeller obeys a logarithmic rule.
Endoscopic classification of representations of quasi-split unitary groups
Mok, Chung Pang
2015-01-01
In this paper the author establishes the endoscopic classification of tempered representations of quasi-split unitary groups over local fields, and the endoscopic classification of the discrete automorphic spectrum of quasi-split unitary groups over global number fields. The method is analogous to the work of Arthur on orthogonal and symplectic groups, based on the theory of endoscopy and the comparison of trace formulas on unitary groups and general linear groups.
Uniqueness of symmetric basis in quasi-Banach spaces
Albiac, F.; Leránoz, C.
2008-12-01
We show that if X is a nonlocally convex natural quasi-Banach space with symmetric basis whose Banach envelope is isomorphic to l1, then all symmetric bases of X are equivalent. The scope of this result is quite ample since the Banach envelopes of natural quasi-Banach spaces with basis always exhibit an l1-like behavior, in the sense that they contain copies of 's uniformly complemented.
Characteristic varieties of quasi-projective manifolds and orbifolds
Bartolo, Enrique Artal; Matei, Daniel
2010-01-01
We prove that the irreducible components of the characteristic varieties of quasi-projective manifolds are either pull-backs of such components for orbifolds, or torsion points. This gives an interpretation for the so-called \\emph{translated} components of the characteristic varieties, and shows that the zero-dimensional components are indeed torsion. The main result is used to derive further obstructions for a group to be the fundamental group of a quasi-projective manifold.
Quasi-rigidity of hyperbolic 3-manifolds and scattering theory
Borthwick, D; Taylor, E; Borthwick, David; Rae, Alan Mc; Taylor, Edward
1996-01-01
Take two isomorphic convex co-compact co-infinite volume Kleinian groups, whose regular sets are diffeomorphic. The quotient of hyperbolic 3-space by these groups gives two hyperbolic 3-manifolds whose scattering operators may be compared. We prove that the operator norm of the difference between the scattering operators is small, then the groups are related by a coorespondingly small quasi-conformal deformation. This in turn implies that the two hyperbolic 3-manifolds are quasi-isometric.
Confronting quasi-exponential inflation with WMAP seven
Energy Technology Data Exchange (ETDEWEB)
Pal, Barun Kumar; Pal, Supratik; Basu, B., E-mail: barunp1985@rediffmail.com, E-mail: pal@th.physik.uni-bonn.de, E-mail: banasri@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 B.T. Road, Kolkata 700 108 (India)
2012-04-01
We confront quasi-exponential models of inflation with WMAP seven years dataset using Hamilton Jacobi formalism. With a phenomenological Hubble parameter, representing quasi exponential inflation, we develop the formalism and subject the analysis to confrontation with WMAP seven using the publicly available code CAMB. The observable parameters are found to fair extremely well with WMAP seven. We also obtain a ratio of tensor to scalar amplitudes which may be detectable in PLANCK.
Strong Converse Inequality for Left Gamma Quasi-Interpolants
Institute of Scientific and Technical Information of China (English)
Qiu-lan Qi; Shun-sheng Guo
2005-01-01
The rate of convergence for the Gamma operators cannot be faster than O(1/n). In order to obtain much faster convergence, quasi-interpolants in the sense of Sablonniere are considered. For the first time in the theory of quasi-interpolants, the strong converse inequality is solved in sup-norm with the K-functional Kaλ(f, t2r) (0≤λ≤ 1, 0＜α＜2r).
Investigation on the Quasi-Cycle of Black Hole Spin
Institute of Scientific and Technical Information of China (English)
WANG Ding-Xiong; XIAO Kan; LEI Wei-Hua
2001-01-01
A reverse condition of accretion flow and its constraints on black hole spin in the quasi-cycle are proposed. It is shown that the necessary condition for the quasi-cycle is that the closed magnetic field lines must dominate over the open ones at the horizon. The efficiency of converting accreted rest mass into radiation energy in the quasicycle is proved to increase with the strength of the magnetic transfer process. In addition, a general expression for the efficiency is derived.
Quasi-doubly periodic solutions to a generalized Lame equation
Pawellek, Michael
2007-01-01
We consider the algebraic form of a generalized Lame equation with five free parameters. By introducing a generalization of Jacobi's elliptic functions we transform this equation to a 1-dim time-independent Schroedinger equation with (quasi-doubly) periodic potential. We show that only for a finite set of integral values for the five parameters quasi-doubly periodic eigenfunctions expressible in terms of generalized Jacobi functions exist. For this purpose we also establish a relation to the generalized Ince equation.
QUASI-INTERPOLATION AND APPROXIMATION VIA NONSEPARABLE SCALING FUNCTION
Institute of Scientific and Technical Information of China (English)
Enbing Lin; Ling Yi
2002-01-01
Quasi-interpolation has been audied in many papers, e.g. , [5]. Here we introduce nonseparable scal-ing function quasi-interpolation and show that its approximation can provide similar convergence propertiesas scalar wavelet system. Several equivalent statements of accuracy of nonseparable scaling function are alsogien. In the numerical experiments, it appears that nonseparable scaling function interpolation has betterconvergonce results than scalar wavelet systems in some cases.
Quasi serializable concurrency control in mobile broadcast environments
Institute of Scientific and Technical Information of China (English)
Dang Depeng; Liu Yunsheng
2007-01-01
The problem of maintaining data consistency in mobile broadcast environments is researched.Quasi serializability is formally defined and analyzed at first.It was shown that quasi serializability is less stringent than serializability when database consistency is maintained for transactions.Then,corresponding concurrency control protocol that supports both update transactions and read-only transactions is outlined for mobile broadcast environments.Finally,the simulation results confirmed that the proposed protocol could improve the response time significantly.
Quasi linear flows on tori regularity of their linearization
Bonetto, F; Gentile, G; Mastropietro, V; Bonetto, Federico; Gallavotti, Giovanni; Gentile, Guido; Mastropietro, Vieri
1996-01-01
Under suitable conditions a flow on a torus C^{(p)}--close, with p large enough, to a quasi periodic diophantine rotation is shown to be conjugated to the quasi periodic rotation by a map that is analytic in the perturbation size. This result is parallel to Moser's theorem stating conjugability in class C^{(p')} for some p'
Energetic Particles Dynamics in Mercury's Magnetosphere
Walsh, Brian M.; Ryou, A.S.; Sibeck, D. G.; Alexeev, I. I.
2013-01-01
We investigate the drift paths of energetic particles in Mercury's magnetosphere by tracing their motion through a model magnetic field. Test particle simulations solving the full Lorentz force show a quasi-trapped energetic particle population that gradient and curvature drift around the planet via "Shabansky" orbits, passing though high latitudes in the compressed dayside by equatorial latitudes on the nightside. Due to their large gyroradii, energetic H+ and Na+ ions will typically collide with the planet or the magnetopause and will not be able to complete a full drift orbit. These simulations provide direct comparison for recent spacecraft measurements from MESSENGER. Mercury's offset dipole results in an asymmetric loss cone and therefore an asymmetry in particle precipitation with more particles precipitating in the southern hemisphere. Since the planet lacks an atmosphere, precipitating particles will collide directly with the surface of the planet. The incident charged particles can kick up neutrals from the surface and have implications for the formation of the exosphere and weathering of the surface
The acceleration of low energy protons by quasi-perpendicular interplanetary shocks
Energy Technology Data Exchange (ETDEWEB)
Erdos, G. (Hungarian Academy of Sciences, Budapest (Hungary). Central Research Inst. for Physics); Balogh, A. (Imperial Coll. of Science and Technology, London (UK). Blackett Lab.)
1990-03-01
New aspects of the acceleration of low energy (35-1000 keV) protons by quasi-perpendicular interplanetary shocks are presented, using observations and numerical simulations. Time reverse trajectory calculations of particles are used to derive the behaviour of the angular distribution and spectrum through the shock. These calculations show that for simple planar geometries of the magnetic field and for a power-law spectrum of pre-accelerated particles the expected omnidirectional enhancements are smaller than observed. Pitch angle distributions in the vicinity of six interplanetary shocks have been determined from the measurements carried out onboard the ISEE-3 spacecraft. Reflection of particles was clearly identifiable by the loss cone type angular distribution observed upstream of the shock. Downstream of the shock, the shape and the energy dependence of the pitch angle distributions provide support for the scatter-free model in some cases. However, the observed spikes at the shock passage and bidirectional upstream distributions measured at the nearest to perpendicular shocks, together with other features of particle spectra and angular distributions which cannot be readily explained by model calculations suggest that fluctuations in the magnetic field might also seriously affect the acceleration process. (author).
Agglomeration of Celecoxib by Quasi Emulsion Solvent Diffusion Method: Effect of Stabilizer
Directory of Open Access Journals (Sweden)
Maryam Maghsoodi
2016-12-01
Full Text Available Purpose: The quasi-emulsion solvent diffusion (QESD has evolved into an effective technique to manufacture agglomerates of API crystals. Although, the proposed technique showed benefits, such as cost effectiveness, that is considerably sensitive to the choice of a stabilizer, which agonizes from a absence of systemic understanding in this field. In the present study, the combination of different solvents and stabilizers were compared to investigate any connections between the solvents and stabilizers. Methods: Agglomerates of celecoxib were prepared by QESD method using four different stabilizers (Tween 80, HPMC, PVP and SLS and three different solvents (methyl acetate, ethyl acetate and isopropyl acetate. The solid state of obtained particles was investigated by differential scanning calorimetry (DSC and Fourier transform infrared (FT-IR spectroscopy. The agglomerated were also evaluated in term of production yield, distribution of particles and dissolution behavior. Results: The results showed that the effectiveness of stabilizer in terms of particle size and particle size distribution is specific to each solvent candidate. A stabilizer with a lower HLB value is preferred which actually increased its effectiveness with the solvent candidates with higher lipophilicity. HPMC appeared to be the most versatile stabilizer because it showed a better stabilizing effect compared to other stabilizers in all solvents used. Conclusion: This study demonstrated that the efficiency of stabilizers in forming the celecoxib agglomerates by QESD was influenced by the HLB of the stabilizer and lipophilicity of the solvents.
Gratale, Matthew D; Ma, Xiaoguang; Davidson, Zoey S; Still, Tim; Habdas, Piotr; Yodh, A G
2016-10-01
We measure the vibrational modes and particle dynamics of quasi-two-dimensional colloidal glasses as a function of interparticle interaction strength. The interparticle attractions are controlled via a temperature-tunable depletion interaction. Specifically, the interparticle attraction energy is increased gradually from a very small value (nearly hard-sphere) to moderate strength (∼4k_{B}T), and the variation of colloidal particle dynamics and vibrations are concurrently probed. The particle dynamics slow monotonically with increasing attraction strength, and the particle motions saturate for strengths greater than ∼2k_{B}T, i.e., as the system evolves from a nearly repulsive glass to an attractive glass. The shape of the phonon density of states is revealed to change with increasing attraction strength, and the number of low-frequency modes exhibits a crossover for glasses with weak compared to strong interparticle attraction at a threshold of ∼2k_{B}T. This variation in the properties of the low-frequency vibrational modes suggests a new means for distinguishing between repulsive and attractive glass states.
On the quasi-one dimensional structure of the cellular detonation in a two-dimensional duct
Uyeda, C. M.; Kurosaka, M.; Ferrante, A.
2015-11-01
We performed numerical simulations of cellular detonations in a 2D duct to establish the validity of the one-dimensional ZND model. The detonation was simulated by solving the Euler equations with a WENO-TCD numerical method using adaptive mesh refinement and a detailed chemical reaction mechanism. The results show that the properties of the ZND model of a 2H2-O2-7Ar reaction are very close to the results of the simulations initiated using three different methods for the area-averaged properties and the properties of particles tracked along their pathlines. Disagreements between the particle properties and the ZND model are greatest near the detonation front where the transverse wave and Mach stem introduce larger jumps in the flow properties than the ZND model predicts. The particle pathlines also exhibit a quasi one-dimensional motion downstream from the detonation front which is supported by the quick decay in the particles' velocity ratio of the vertical to horizontal velocity components, in the reference frame attached to the detonation front. These findings show the quasi one-dimensional nature of 2D detonations and the applicability of the ZND model.
A Hamiltonian interpretation of Penrose's quasi-local mass
Mason, L. J.
1989-02-01
A connection is established between Penrose's definition of quasi-local mass and the more conventional notions of mass, momentum etc., arising from the canonical formalism of general relativity (which exist at least asymptotically). It is shown that each component of the 'angular momentum' twistor can be thought of as the value of a Hamiltonian which generates motions of regions of the spacetime which tend towards one of a collection of 'quasi-Killing vectors' on the bounding 2-surface on which the computations take place. The quasi-Killing vectors are obtained from solutions of the twistor equation, and essential use is made of the spinorial version of the gravitational Hamiltonian first employed in Witten's simplified proof of positive energy in general relativity. These ideas are then used to suggest a variation on Penrose's quasi-local mass definition using 'quasi-conformal Killing vectors' rather than quasi-Killing vectors. This has the advantage that there are only sixteen real quantities rather than the twenty real (ten complex) ones from Penrose's original definition.
Collinson, Chris
1995-01-01
* Assumes no prior knowledge* Adopts a modelling approach* Numerous tutorial problems, worked examples and exercises included* Elementary topics augmented by planetary motion and rotating framesThis text provides an invaluable introduction to mechanicsm confining attention to the motion of a particle. It begins with a full discussion of the foundations of the subject within the context of mathematical modelling before covering more advanced topics including the theory of planetary orbits and the use of rotating frames of reference. Truly introductory , the style adoped is perfect for those u
Quantum effects for particles channeling in a bent crystal
Feranchuk, Ilya; San, Nguyen Quang
2016-09-01
Quantum mechanical theory for channeling of the relativistic charged particles in the bent crystals is considered in the paper. Quantum effects of under-barrier tunneling are essential when the radius of the curvature is closed to its critical value. In this case the wave functions of the quasi-stationary states corresponding to the particles captured in a channel are presented in the analytical form. The efficiency of channeling of the particles and their angular distribution at the exit crystal surface are calculated. Characteristic experimental parameters for observation the quantum effects are estimated.
Energy exchange in systems of particles with nonreciprocal interaction
Energy Technology Data Exchange (ETDEWEB)
Vaulina, O. S.; Lisina, I. I., E-mail: Irina.Lisina@mail.ru; Lisin, E. A. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)
2015-10-15
A model is proposed to describe the sources of additional kinetic energy and its redistribution in systems of particles with a nonreciprocal interaction. The proposed model is shown to explain the qualitative specific features of the dust particle dynamics in the sheath region of an RF discharge. Prominence is given to the systems of particles with a quasi-dipole–dipole interaction, which is similar to the interaction induced by the ion focusing effects that occur in experiments on a laboratory dusty plasma, and with the shadow interaction caused by thermophoretic forces and Le Sage’s forces.
Cooper, Necia Grant; West, Geoffrey B.
1988-06-01
Preface; Introduction; Part I. Theoretical Framework: 1. Scale and dimension - From animals to quarks Geoffrey B. West; 2. Particle physics and the standard model Stuart Raby, Richard C. Slansky and Geoffrey B. West; QCD on a Cray: the masses of elementary particles Gerald Guralnik, Tony Warnock and Charles Zemach; Lecture Notes - From simple field theories to the standard model; 3. Toward a unified theory: an essay on the role of supergravity in the search for unification Richard C. Slansky; 4. Supersymmetry at 100 GeV Stuart Raby; 5. The family problem T. Goldman and Michael Martin Nieto; Part II. Experimental Developments: 6. Experiments to test unification schemes Gary H. Sanders; 7. The march toward higher energies S. Peter Rosen; LAMPF II and the High-Intensity Frontier Henry A. Thiessen; The SSC - An engineering challenge Mahlon T. Wilson; 8. Science underground - the search for rare events L. M. Simmons, Jr; Part III. Personal Perspectives: 9. Quarks and quirks among friends Peter A. Carruthers, Stuart Raby, Richard C. Slansky, Geoffrey B. West and George Zweig; Index.
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Quasi-likelihood nonlinear models (QLNM) include generalized linear models as a special case.Under some regularity conditions,the rate of the strong consistency of the maximum quasi-likelihood estimation (MQLE) is obtained in QLNM.In an important case,this rate is O(n-1/2(loglogn)1/2),which is just the rate of LIL of partial sums for I.I.d variables,and thus cannot be improved anymore.
Institute of Scientific and Technical Information of China (English)
沈辉; 徐雪青; 王伟
2003-01-01
The surface morphology of quasi-periodic stripe-shaped patterns of magnetite fluids was observed in applied perpendicular magnetic fields by means of scanning electron microscopy. The nanoparticles of the magnetite fluids are arranged in oriental quasilinear chains in applied perpendicular magnetic fields as observed using transmission electron microscopy. This arrangement results from particle-particle interactions and particle-carrier liquids interactions, which are eventually controlled by the magnetic fields distribution.
Hastings, M B
2010-01-01
We present a possible definition of a mobility gap for a many-body quantum system, in analogy to definitions of dynamical localization for single particle systems. Using this definition, we construct "corrected" quasi-adiabatic continuation operators. Under an appropriate definition of a unique ground state, we show how to introduce virtual fluxes. Armed with these results, we can directly carry over previous results in the case of a spectral gap. We present a proof of decay of correlation functions and we present a proof of Hall conductance quantization under very mild density-of-states assumptions defined later. We also generalize these definitions to the case of a "bulk mobility gap", in the case of a system with boundaries, and present a proof of Hall conductance quantization on an annulus under appropriate assumptions. Further, we present a new "optimized" quasi-adiabatic continuation operator which simplifies previous estimates and tightens bounds in certain cases. This is presented in an appendix which...
Directory of Open Access Journals (Sweden)
D. R. Shklyar
2011-06-01
Full Text Available When a quasi-monochromatic wave propagating in an inhomogeneous magnetoplasma has sufficiently large amplitude, there exist phase-trapped resonant particles whose energy increases or decreases depending on the "sign" of inhomogeneity. The variation of energy density of such particles can greatly exceed the wave energy density which contradicts energy conservation under the prevalent assumption that the wave serves as the energy source or sink. We show that, in fact, the energy increase (or decrease of phase-trapped particles is related to energy transfer from (to phase untrapped particles, while the wave basically mediates the energization process. Virtual importance of this comprehension consists in setting proper quantitative constraints on attainable particle energy. The results have immediate applications to at least two fundamental problems in the magnetospheric physics, i.e. particle dynamics in the radiation belts and whistler-triggered emissions.
Average observed properties of the Earth's quasi-perpendicular and quasi-parallel bow shock
Czaykowska, A; Treumann, R A; Baumjohann, W
2000-01-01
We present a statistical analysis of 132 dayside (LT 0700-1700) bow shock crossings of the AMPTE/IRM spacecraft. We perform a superposed epoch analysis of plasma and magnetic field parameters as well as of low frequency magnetic power spectra some minutes upstream and downstream of the bow shock by dividing the events into categories depending on the angle between bow shock normal and interplanetary magnetic field and on the plasma-beta, i.e., the ratio of plasma to magnetic pressure. Downstream of the quasi-perpendicular low-beta (beta 1.0) crossings mirror waves are identified. However, there are also cases where the conditions for mirror modes are met downstream of the nearly perpendicular shock, but no mirror waves are observed.
Quasi-Nearly Subharmonicity and Separately Quasi-Nearly Subharmonic Functions
Directory of Open Access Journals (Sweden)
Riihentaus Juhani
2008-01-01
Full Text Available Abstract Wiegerinck has shown that a separately subharmonic function need not be subharmonic. Improving previous results of Lelong, Avanissian, Arsove, and of us, Armitage and Gardiner gave an almost sharp integrability condition which ensures a separately subharmonic function to be subharmonic. Completing now our recent counterparts to the cited results of Lelong, Avanissian and Arsove for so-called quasi-nearly subharmonic functions, we present a counterpart to the cited result of Armitage and Gardiner for separately quasinearly subharmonic function. This counterpart enables us to slightly improve Armitage's and Gardiner's original result, too. The method we use is a rather straightforward and technical, but still by no means easy, modification of Armitage's and Gardiner's argument combined with an old argument of Domar.
Quasi-Nearly Subharmonicity and Separately Quasi-Nearly Subharmonic Functions
Directory of Open Access Journals (Sweden)
Juhani Riihentaus
2008-09-01
Full Text Available Wiegerinck has shown that a separately subharmonic function need not be subharmonic. Improving previous results of Lelong, Avanissian, Arsove, and of us, Armitage and Gardiner gave an almost sharp integrability condition which ensures a separately subharmonic function to be subharmonic. Completing now our recent counterparts to the cited results of Lelong, Avanissian and Arsove for so-called quasi-nearly subharmonic functions, we present a counterpart to the cited result of Armitage and Gardiner for separately quasinearly subharmonic function. This counterpart enables us to slightly improve Armitage's and Gardiner's original result, too. The method we use is a rather straightforward and technical, but still by no means easy, modification of Armitage's and Gardiner's argument combined with an old argument of Domar.
Observations of the sedimentation of individual particles in a quasi-two dimensional system
Ramos, Eduardo; Lee, Andrew; Goldman, Daniel; Swinney, Harry
2002-11-01
We report observations of single sedimenting acrylic spheres (diameter = 3.175 mm, relative density = 1.19) in a vertical Hele-Shaw cell formed by two parallel glass plates and filled with water. The distance between walls of the cell varies from 1.1 to 1.3 sphere diameters; the corresponding sedimenting Reynolds number varies from 220 to 300. In the narrower cell, a wake was formed by an attached vortical region behind the sphere with two asymetrical branches. These branches oscillated and shed vortices alternately; this structure is similar to the Von Karman vortex street generated by a fixed cylinder exposed to a constant flow at approximately the same Reynolds number. In contrast, the wake of a sphere falling in a cell with a gap of 1.3 diameters was similar to that for a sphere in an infinite system at Reynolds numbers slightly larger than the threshhold for the onset of periodic wake oscillations (Re 300): the sphere sheds vortex loops, which are separated by counterotating pairs of vortex filaments.
High Resolution Angle Resolved Photoemission Studies on Quasi-Particle Dynamics in Graphite
Energy Technology Data Exchange (ETDEWEB)
Leem, C.S.
2010-06-02
We obtained the spectral function of the graphite H point using high resolution angle resolved photoelectron spectroscopy (ARPES). The extracted width of the spectral function (inverse of the photo-hole lifetime) near the H point is approximately proportional to the energy as expected from the linearly increasing density of states (DOS) near the Fermi energy. This is well accounted by our electron-phonon coupling theory considering the peculiar electronic DOS near the Fermi level. And we also investigated the temperature dependence of the peak widths both experimentally and theoretically. The upper bound for the electron-phonon coupling parameter is 0.23, nearly the same value as previously reported at the K point. Our analysis of temperature dependent ARPES data at K shows that the energy of phonon mode of graphite has much higher energy scale than 125K which is dominant in electron-phonon coupling.
Maxwell consideration of polaritonic quasi-particle Hamiltonians in multi-level systems
Energy Technology Data Exchange (ETDEWEB)
Richter, Steffen; Michalsky, Tom; Fricke, Lennart; Sturm, Chris; Franke, Helena; Grundmann, Marius; Schmidt-Grund, Rüdiger [Institut für Experimentelle Physik II, Universität Leipzig, Linnéstr. 5, 04103 Leipzig (Germany)
2015-12-07
We address the problem of the correct description of light-matter coupling for excitons and cavity photons in the case of systems with multiple photon modes or excitons, respectively. In the literature, two different approaches for the phenomenological coupling Hamiltonian can be found: Either one single Hamiltonian with a basis whose dimension equals the sum of photonic modes and excitonic resonances is used. Or a set of independent Hamiltonians, one for each photon mode, is chosen. Both are usually used equivalently for the same kind of multi-photonic systems which cannot be correct. However, identifying the suitable Hamiltonian is difficult when modeling experimental data. By means of numerical transfer matrix calculations, we demonstrate the scope of application of each approach: The first one holds only for the coupling of a single photon state to several excitons, while in the case of multiple photon modes, separate Hamiltonians must be used for each photon mode.
One-parameter quasi-filled function algorithm for nonlinear integer programming
Institute of Scientific and Technical Information of China (English)
SHANG You-lin; HAN Bo-shun
2005-01-01
A definition of the quasi-filled function for nonlinear integer programming problem is given in this paper. A quasi-filled function satisfying our definition is presented. This function contains only one parameter. The properties of the proposed quasi-filled function and the method using this quasi-filled function to solve nonlinear integer programming problem are also discussed in this paper. Numerical results indicated the efficiency and reliability of the proposed quasi-filled function algorithm.
Factorisable Quasi-adequate Semigroups%因子拟适当半群
Institute of Scientific and Technical Information of China (English)
彭婷婷; 郭小江
2011-01-01
In this paper, we investigate a class of factorisable IC quasi-adequate semigroups,so-called, factorisable IC quasi-adequate semigroups of type-(H, I). Some characterizations of factorisable IC quasi-adequate semigroups of type-(H, I) are obtained. In particular, we prove that any IC quasi-adequate semigroup has a factorisable IC quasi-adequate subsemigroups of type-(H, I) and a band of cancellative monoids.
A field theoretical approach to the quasi-continuum method
Iyer, Mrinal; Gavini, Vikram
2011-08-01
The quasi-continuum method has provided many insights into the behavior of lattice defects in the past decade. However, recent numerical analysis suggests that the approximations introduced in various formulations of the quasi-continuum method lead to inconsistencies—namely, appearance of ghost forces or residual forces, non-conservative nature of approximate forces, etc.—which affect the numerical accuracy and stability of the method. In this work, we identify the source of these errors to be the incompatibility of using quadrature rules, which is a local notion, on a non-local representation of energy. We eliminate these errors by first reformulating the extended interatomic interactions into a local variational problem that describes the energy of a system via potential fields. We subsequently introduce the quasi-continuum reduction of these potential fields using an adaptive finite-element discretization of the formulation. We demonstrate that the present formulation resolves the inconsistencies present in previous formulations of the quasi-continuum method, and show using numerical examples the remarkable improvement in the accuracy of solutions. Further, this field theoretic formulation of quasi-continuum method makes mathematical analysis of the method more amenable using functional analysis and homogenization theories.
Kinetics of Photocatalytic Degradation of Methylene Blue over TiO2 Particles in Aqueous Suspensions
Institute of Scientific and Technical Information of China (English)
史载锋; 范益群; 徐南平; 时钧
2000-01-01
The kinetics of photodegradation of methylene blue over UV light illuminated titania particles in aqueous suspensions has been studied with different initial methylene blue concentrations and TiO2 particle sizes. The degradation rate increases with the decrease of initial concentration and particle size. A quasi-experienced model for photodegradation rate is derived based mainly on the coinstantaneous effects of different initial concentrations and particle sizes. The mathematical relationships of model parameters with initial concentration and particle size are given. The model results of the photodegradation rate of methylene blue are coincident with the experimental data.
Laser-driven platform for generation and characterization of strong quasi-static magnetic fields
Santos, J J; Giuffrida, L; Forestier-Colleoni, P; Fujioka, S; Zhang, Z; Korneev, Ph; Bouillaud, R; Dorard, S; Batani, D; Chevrot, M; Cross, J; Crowston, R; Dubois, J -L; Gazave, J; Gregori, G; d'Humières, E; Hulin, S; Ishihara, K; Kojima, S; Loyez, E; Marquès, J -R; Morace, A; Nicolaï, Ph; Peyrusse, O; Poyé, A; Raffestin, D; Ribolzi, J; Roth, M; Schaumann, G; Serres, F; Tikhonchuk, V T; Vacar, Ph; Woolsey, N
2015-01-01
Quasi-static magnetic-fields up to $800\\,$T are generated in the interaction of intense laser pulses (500J, 1ns, 10^{17}W/cm^2) with capacitor-coil targets of different materials. The reproducible magnetic-field was consistently measured by three independent diagnostics: GHz-bandwidth inductor pickup coils (B-dot probes), Faraday rotation of polarized optical laser light and proton beam-deflectometry. The field rise time is consistent with the laser pulse duration, and it has a dipole-like distribution over a characteristic volume of 1mm^3, which is coherent with theoretical expectations. These results demonstrate a very efficient conversion of the laser energy into magnetic fields, thus establishing a robust laser-driven platform for reproducible, well characterized, generation of quasi-static magnetic fields at the kT-level, as well as for magnetization and accurate probing of high-energy-density samples driven by secondary powerful laser or particle beams.
Kinetic Theory of a Confined Quasi-Two-Dimensional Gas of Hard Spheres
Directory of Open Access Journals (Sweden)
J. Javier Brey
2017-02-01
Full Text Available The dynamics of a system of hard spheres enclosed between two parallel plates separated a distance smaller than two particle diameters is described at the level of kinetic theory. The interest focuses on the behavior of the quasi-two-dimensional fluid seen when looking at the system from above or below. In the first part, a collisional model for the effective two-dimensional dynamics is analyzed. Although it is able to describe quite well the homogeneous evolution observed in the experiments, it is shown that it fails to predict the existence of non-equilibrium phase transitions, and in particular, the bimodal regime exhibited by the real system. A critical revision analysis of the model is presented , and as a starting point to get a more accurate description, the Boltzmann equation for the quasi-two-dimensional gas has been derived. In the elastic case, the solutions of the equation verify an H-theorem implying a monotonic tendency to a non-uniform steady state. As an example of application of the kinetic equation, here the evolution equations for the vertical and horizontal temperatures of the system are derived in the homogeneous approximation, and the results compared with molecular dynamics simulation results.
Quasi-three-dimensional refined modelling of turbulent flow and water quality in coastal waters
Institute of Scientific and Technical Information of China (English)
沈永明; 李玉成; AllenT.CHWANG
1996-01-01
The water quality in Victoria Harbour.Hong Kong is dominated by strong seasonal effects resulting from the variation in freshwater discharge into the Pearl Estuary.The quasi-three-dimensional water quality model has been developed to simulate the variations in water quality and the ecosystem in the harbour.The model is unique in that it completely integrates the refined modelling of the hydrodynamics,biochemical reactions and the ecosystem in the harbour.It is a quasi-three-dimensional segmented model which is capable of resolving mean daily variations in all the parameters relevant to pollution control.It predicts daily fluctuations in the oxygen content at different depths in water throughout the year.It takes into account transport and settling of pollutant particles.It predicts light penetration from computed turbidity variations.It includes interactions between the ecosystem and water quality,through nutrient cycling and photosynthesis.The model has been calibrated well against the data set of hist
A quasi-continuum hydrodynamic model for slit shaped nanochannel flow
Bhadauria, Ravi; Aluru, N. R.
2013-08-01
We propose a quasi-continuum hydrodynamic model for isothermal transport of Lennard-Jones fluid confined in slit shaped nanochannels. In this work, we compute slip and viscous contributions independently and superimpose them to obtain the total velocity profile. Layering of fluid near the interface plays an important role in viscous contribution to the flow, by apparent viscosity change along the confining dimension. This relationship necessitates computing density profiles, which is done using the recently proposed empirical-potential based quasi-continuum theory [A. V. Raghunathan, J. H. Park, and N. R. Aluru, J. Chem. Phys. 127, 174701 (2007)], 10.1063/1.2793070. Existing correlations for density dependent viscosity provided by Woodcock [AIChE J. 52, 438 (2006)], 10.1002/aic.10676 are used to compute viscosity profile in the nanopores. A Dirichlet type slip boundary condition based on a static Langevin friction model describing center-of-mass motion of fluid particles is used, the parameters of which are dependent on the fluctuations of total wall-fluid force from an equilibrium molecular dynamics simulation. Different types of corrugated surfaces are considered to study wall-fluid friction effects on boundary conditions. Proposed hydrodynamic model yields good agreement of velocity profiles obtained from non-equilibrium molecular dynamics simulations for gravity driven flow.
Material property measurement using the quasi-Scholte mode-A waveguide sensor
Cegla, F. B.; Cawley, P.; Lowe, M. J. S.
2005-03-01
In the food industry and other industries, rheological measurements and determination of particle sizes in suspensions and emulsions is of great importance for process and quality control. Current test cell based ultrasonic methods exist but are often inconvenient. An attractive alternative could be to insert a simple measurement ``dipstick'' into the fluid; this paper presents an initial study of the feasibility of using measurements of the velocity and attenuation of the quasi-Scholte mode on a plate to obtain the longitudinal velocity and attenuation of an embedding medium. The attenuation of the quasi-Scholte mode is caused by two mechanisms: shear leakage and attenuation due to the bulk longitudinal attenuation of the embedding material. In a calibration test the bulk longitudinal velocity and viscosity of glycerol were determined experimentally. Measurements agreed well with results from conventional methods and literature data. Quantitative results and an independent validation for honey, a very viscous fluid, are also presented. For Newtonian liquids like glycerol and honey, the shear leakage and longitudinal bulk attenuation are both related to viscosity. To demonstrate the sensitivity to nonviscous attenuation mechanisms, qualitative measurement results on fluids that mainly exhibit attenuation due to scattering are presented. .
Antonella Del Rosso
2014-01-01
These devices are designed to provide a current pulse of 5000 Amps which will in turn generate a fast magnetic pulse that steers the incoming beam into the LHC. Today, the comprehensive upgrade of the LHC injection kicker system is entering its final stages. The upgraded system will ensure the LHC can be refilled without needing to wait for the kicker magnets to cool, thus enhancing the performance of the whole accelerator. An upgraded kicker magnet in its vacuum tank, with an upgraded beam screen. The LHC is equipped with two kicker systems installed at the injection points (near points 2 and 8, see schematic diagram) where the particle beams coming from the SPS are injected into the accelerator’s orbit. Each system comprises four magnets and four pulse generators in which the field rises to 0.12 Tesla in less than 900 nanoseconds and for a duration of approximately 8 microseconds. Although the injection kickers only pulse 12 times to fill the LHC up with beam, the LHC beam circ...
Kemaneci, Efe; Graef, Wouter; van Dijk, Jan; Kroesen, Gerrit M W
2015-01-01
Collisional and radiative dynamics of a plasma is exposed by so-called Collisional Radiative Models [1] that simplify the chemical kinetics by quasi-steady state assignment on certain types of particles. The assignment is conventionally based on the classification of the plasma species by the ratio of the transport to the local destruction frequencies. We show that the classification is not exact due to the role of the time-dependent local production, and a measure is necessary to confirm the validity of the assignment. The main goal of this study is to evaluate a measure on the quasi-steady state assumptions of these models. Inspired by a chemical reduction technique called Intrinsic Low Dimensional Manifolds [2, 3], an estimate local source is provided at the transport time-scale. This source is a deviation from the quasi-steady state for the particle and its value is assigned as an error of the quasi-steady state assumption. The propagation of this error on the derived quantities is formulated in the Colli...
Particle Diffusion and Acceleration by Shock Wave in Magnetized Filamentary Turbulence
Honda, M; Honda, Mitsuru; Honda, Yasuko S.
2005-01-01
We expand the off-resonant scattering theory for particle diffusion in magnetized current filaments that can be typically compared to astrophysical jets, including active galactic nucleus jets. In a high plasma beta region where the directional bulk flow is a free-energy source for establishing turbulent magnetic fields via current filamentation instabilities, a novel version of quasi-linear theory to describe the diffusion of test particles is proposed. The theory relies on the proviso that the injected energetic particles are not trapped in the small-scale structure of magnetic fields wrapping around and permeating a filament but deflected by the filaments, to open a new regime of the energy hierarchy mediated by a transition compared to the particle injection. The diffusion coefficient derived from a quasi-linear type equation is applied to estimating the timescale for the stochastic acceleration of particles by the shock wave propagating through the jet. The generic scalings of the achievable highest ener...
The formation of the ion seed population at quasi-parallel shocks
Johlander, Andreas; Vaivads, Andris; Khotyaintsev, Yuri; Retino, Alessandro; Dandouras, Iannis; Yordanova, Emiliya; André, Mats
2015-04-01
Collisionless shocks in space plasma are known to be capable of accelerating particles to very high energies through Fermi acceleration. However, this process requires an injection of a suprathermal ion seed population. The process of how the ion seed population is formed is still not fully understood. In this work, we studied the formation of the ion seed population as a result of solar wind ions being reflected off short large amplitude magnetic structures (SLAMS) in the quasi-parallel bow shock of Earth. For our analysis, we used field and particle data from the four Cluster satellites. In order to follow the ion dynamics at fast temporal scales we used ion subspin data from times when the separation of the satellites was ~ 100 km. We have found that SLAMS nearly specularly reflect solar wind ions through magnetic mirroring. We have also performed test particle simulations of ions encountering a SLAMS using field data from the satellites. The simulations show that solar wind ions with lower energy are more likely to be reflected off the SLAMS while high energy ions pass through the SLAMS, which is consistent with observational ion data. Additionally, high energy ions are observed upstream of the shock. These are most likely ions that were reflected off a SLAMS and energy conservation in the solar wind frame causes an increase of energy in the spacecraft frame.
Characterization of V-modules by Relative Quasi-continuity
Institute of Scientific and Technical Information of China (English)
LIU Zhong-kui
2001-01-01
We characterize V-modules by relative (quasi-)continuity of left R-modules in this paper. It is shown that a left R-module M is a V-module if and only if every finitely cogenerated left R- module in σ[M] is - (quasi-)continuous if and only if every left R-module in σ[M] is -continuous, where is the set of all simple left R- modules. We also show that a left R- module M is a locally noetherian V- module if and only if every semisimple left R-module (in σ[M]) is M- injective ff and only if every essential extension in σ[M] of every semisimple left R-module in σ[M] is 2-(quasi-)continuous, where 2 is the set of all semisimple left R-modules.
Quasi-Optical 34-GHz Rf Pulse Compressor
Energy Technology Data Exchange (ETDEWEB)
Hirshfield, Jay L
2007-06-19
Designs have been carried out on non-high-vacuum, low-power versions of three- and four-mirror quasi-optical passive and active Ka-band pulse compressors, and prototypes built and tested based on these designs. The active element is a quasi-optical grating employing gas discharge tubes in the gratings. Power gains of about 3:1 were observed experimentally for the passive designs, and about 7:1 with the active designs. High-power, high-vacuum versions of the three-and four-mirror quasi-optical pulse compressors were built and tested at low power. These now await installation and testing using multi-MW power from the 34-GHz magnicon.
Mapping from quasi-elastic scattering to fusion reactions
Hagino, K
2014-01-01
The fusion barrier distribution has provided a nice representation for the channel coupling effects on heavy-ion fusion reactions at energies around the Coulomb barrier. Here we discuss how one can extract the same representation using the so called sum-of-differences (SOD) method with quasi-elastic scattering cross sections. In contrast to the conventional quasi-elastic barrier distribution, the SOD barrier distribution has an advantage in that it can be applied both to non-symmetric and symmetric systems. It is also the case that the correspondence to the fusion barrier distribution is much better than the quasi-elastic barrier distribution. We demonstrate its usefulness by studying $^{16}$O+$^{144}$Sm, $^{58}$Ni+$^{58}$Ni, and $^{12}$C+$^{12}$C systems.
Quasi-Koszul-like modules%拟Koszul-like模
Institute of Scientific and Technical Information of China (English)
吕家凤; 包科维; 叶晓晓; 王一帆
2011-01-01
It was discussed the Koszul-like property of finitely generated modules over a Noetherian semiperfect algebra. Motivated by the minimal graded projective resolution of a Koszul-like module, quasi-Koszul-like module was introduced. The Ext module of a quasi-Koszul-like module was studied in detail, which generalized some properties of Koszul-like modules to quasi-Koszul-like modules.%主要讨论了诺特半完全代数上有限生成模的Koszul-like性质.受分次Koszul-like模的极小分次投射分解的启发,定义了拟Koszul-like模.讨论了拟Koszul-like模的Ext模的性质,把Koszul-like模的一些性质推广到拟Koszul-like模的情形.
Quasi-lattices of qubits for generating inequivalent multipartite entanglements
Ian, Hou
2016-06-01
The mesoscopic scale of superconducting qubits makes their inter-spacings comparable to the scale of wavelength of a circuit cavity field to which they commonly couple. This comparability results in inhomogeneous coupling strengths for each qubit and hence asynchronous Rabi excitation cycles among the qubits that form a quasi-lattice. We find that such inhomogeneous coupling benefits the formation of multi-photon resonances between the single-mode cavity field and the quasi-lattice. The multi-photon resonances lead, in turn, to the simultaneous generation of inequivalent |\\text{GHZ}> and |W> types of multipartite entanglement states, which are not transformable to each other through local operations with classical communications. Applying the model on the 3-qubit quasi-lattice and using the entanglement measures of both concurrence and 3-tangle, we verify that the inhomogeneous coupling specifically promotes the generation of the totally inseparable |\\text{GHZ}> state.
Quasi-objects, Cult Objects and Fashion Objects
DEFF Research Database (Denmark)
Andersen, Bjørn Schiermer
2011-01-01
This article attempts to rehabilitate the concept of fetishism and to contribute to the debate on the social role of objects as well as to fashion theory. Extrapolating from Michel Serres’ theory of the quasi-objects, I distinguish two phenomenologies possessing almost opposite characteristics....... These two phenomenologies are, so I argue, essential to quasi-object theory, yet largely ignored by Serres’ sociological interpreters. They correspond with the two different theories of fetishism found in Marx and Durkheim, respectively. In the second half of the article, I introduce the fashion object...... as a unique opportunity for studying the interchange between these two forms of fetishism and their respective phenomenologies. Finally, returning to Serres, I briefly consider the theoretical consequences of introducing the fashion object as a quasi-object....
Quasi-local approach to general universal horizons
Maciel, Alan
2015-01-01
Theories of gravity with a preferred foliation usually display arbitrarily fast signal propagation, changing the black hole definition. A new inescapable barrier, the universal horizon, has been defined and many static and spherically symmetric examples have been studied in the literature. Here, we translate the usual definition of universal horizon in terms of an optical scalar built with the preferred flow defined by the preferred spacetime foliation. The new expression have the advantage of being of quasi-local nature and not depend on specific spacetime symmetries to be well defined. Therefore, we propose it as a definition for general quasi-local universal horizons. We also to give a general (peeling) surface gravity definition for general spacetimes. Using the new formalism we show that there are no universal analog of cosmological horizons for FLRW models, for any scale factor function and we also state that quasi-local universal horizons are restricted to trapped regions of the spacetime. We analyze t...
Quasi-Normal Modes of Stars and Black Holes
Directory of Open Access Journals (Sweden)
Kokkotas Kostas
1999-01-01
Full Text Available Perturbations of stars and black holes have been one of the main topics of relativistic astrophysics for the last few decades. They are of particular importance today, because of their relevance to gravitational wave astronomy. In this review we present the theory of quasi-normal modes of compact objects from both the mathematical and astrophysical points of view. The discussion includes perturbations of black holes (Schwarzschild, Reissner-Nordström, Kerr and Kerr-Newman and relativistic stars (non-rotating and slowly-rotating. The properties of the various families of quasi-normal modes are described, and numerical techniques for calculating quasi-normal modes reviewed. The successes, as well as the limits, of perturbation theory are presented, and its role in the emerging era of numerical relativity and supercomputers is discussed.
Quasi-Normal Modes from Non-Commutative Matrix Dynamics
Aprile, Francesco
2016-01-01
We explore the connection between the process of relaxation in the BMN matrix model and the physics of black holes in AdS/CFT. Focusing on Dyson-fluid solutions of the matrix model, we perform numerical simulations of the real time dynamics of the system. By quenching the equilibrium distribution we study the quasi-normal oscillations of scalar single trace observables, we isolate the lowest quasi-normal mode, and we determine its frequencies as function of the energy. Considering the BMN matrix model as a truncation of $\\mathcal{N}=4$ SYM, we also compute the frequencies of the quasi-normal modes of the dual scalar fields in the AdS$_5$-Schwarzschild background. We compare the results of the black hole and the classical Dyson fluid, and we point out a correspondence between the two descriptions.
Completely generalized multivalued nonlinear quasi-variational inclusions
Directory of Open Access Journals (Sweden)
Zeqing Liu
2002-01-01
Full Text Available We introduce and study a new class of completely generalized multivalued nonlinear quasi-variational inclusions. Using the resolvent operator technique for maximal monotone mappings, we suggest two kinds of iterative algorithms for solving the completely generalized multivalued nonlinear quasi-variational inclusions. We establish both four existence theorems of solutions for the class of completely generalized multivalued nonlinear quasi-variational inclusions involving strongly monotone, relaxed Lipschitz, and generalized pseudocontractive mappings, and obtain a few convergence results of iterative sequences generated by the algorithms. The results presented in this paper extend, improve, and unify a lot of results due to Adly, Huang, Jou-Yao, Kazmi, Noor, Noor-Al-Said, Noor-Noor, Noor-Noor-Rassias, Shim-Kang-Huang-Cho, Siddiqi-Ansari, Verma, Yao, and Zhang.
Luttinger parameter of quasi-one-dimensional para -H2
Ferré, G.; Gordillo, M. C.; Boronat, J.
2017-02-01
We have studied the ground-state properties of para-hydrogen in one dimension and in quasi-one-dimensional configurations using the path-integral ground-state Monte Carlo method. This method produces zero-temperature exact results for a given interaction and geometry. The quasi-one-dimensional setup has been implemented in two forms: the inner channel inside a carbon nanotube coated with H2 and a harmonic confinement of variable strength. Our main result is the dependence of the Luttinger parameter on the density within the stable regime. Going from one dimension to quasi-one dimension, keeping the linear density constant, produces a systematic increase of the Luttinger parameter. This increase is, however, not enough to reach the superfluid regime and the system always remain in the quasicrystal regime, according to Luttinger liquid theory.
Characteristic modules and tensor products over quasi-hereditary algebras
Institute of Scientific and Technical Information of China (English)
Yue-hui ZHANG; Shi-ying SHEN; Ping-kai YE
2007-01-01
Let A be a monomial quasi-hereditary algebra with a pure strong exact Borel subalgebra B. It is proved that the category of induced good modules over B is contained in the category of good modules over A; that the characteristic module of A is an induced module of that of B via the exact functor - (×)B A if and only if the induced A-module of an injective B-module remains injective as a B-module. Moreover, it is shown that an exact Borel subalgebra of a basic quasi-hereditary serial algebra is right serial and that the characteristic module of a basic quasi-hereditary serial algebra is exactly the induced module of that of its exact Borel subalgebra.
Characteristic modules and tensor products over quasi-hereditary algebras
Institute of Scientific and Technical Information of China (English)
2007-01-01
Let A be a monomial quasi-hereditary algebra with a pure strong exact Borel subalgebra B.It is proved that the category of induced good modules over B is contained in the category of good modules over A;that the characteristic module of A is an induced module of that of B via the exact functor-(?)_B A if and only if the induced A-module of an injective B-module remains injective as a B-module.Moreover,it is shown that an exact Borel subalgebra of a basic quasi-hereditary serial algebra is right serial and that the characteristic module of a basic quasi-hereditary serial algebra is exactly the induced module of that of its exact Borel subalgebra.
{ P }{ T } symmetry in quasi-integrable models
Assis, P. E. G.
2016-06-01
Observations of almost stable scattering in nonintegrable models have been reinforced and a framework is proposed to describe quasi-integrability in terms of { P }{ T } symmetry. This new mechanism can be used to regard { P }{ T } symmetry in classical field theories as a guiding principle to also select relevant systems when it comes to integrability properties. It turns out that the if a deformed Lax pair is invariant under this symmetry, corresponding to the unbroken { P }{ T }-symmetric regime, quasi-integrable excitations are produced with asymptotically conserved charges. A generic nonlinear field equation is used in order to verify the validity of the assumptions but results for a specific non-integrable class of models are also presented. A set of quasi-integrable excitations is investigated and shown to have spectral functions with appropriate properties, which might lead to the determination of the almost conserved charges.
Thermodynamical Study of FRW Universe in Quasi-Topological Theory
Directory of Open Access Journals (Sweden)
H. Moradpour
2016-01-01
Full Text Available By applying the unified first law of thermodynamics on the apparent horizon of FRW universe, we get the entropy relation for the apparent horizon in quasi-topological gravity theory. Throughout the paper, the results of considering the Hayward-Kodama and Cai-Kim temperatures are also addressed. Our study shows that whenever there is no energy exchange between the various parts of cosmos, we can get an expression for the apparent horizon entropy in quasi-topological gravity, which is in agreement with other attempts that followed different approaches. The effects of a mutual interaction between the various parts of cosmos on the apparent horizon entropy as well as the validity of second law of thermodynamics in quasi-topological gravity are perused.
Design of a 9-loop quasi-exponential waveform generator.
Banerjee, Partha; Shukla, Rohit; Shyam, Anurag
2015-12-01
We know in an under-damped L-C-R series circuit, current follows a damped sinusoidal waveform. But if a number of sinusoidal waveforms of decreasing time period, generated in an L-C-R circuit, be combined in first quarter cycle of time period, then a quasi-exponential nature of output current waveform can be achieved. In an L-C-R series circuit, quasi-exponential current waveform shows a rising current derivative and thereby finds many applications in pulsed power. Here, we have described design and experiment details of a 9-loop quasi-exponential waveform generator. In that, design details of magnetic switches have also been described. In the experiment, output current of 26 kA has been achieved. It has been shown that how well the experimentally obtained output current profile matches with the numerically computed output.
A quasi-linear gyrokinetic transport model for tokamak plasmas
Casati, Alessandro
2012-01-01
The development of a quasi-linear gyrokinetic transport model for tokamak plasmas, ultimately designed to provide physically comprehensive predictions of the time evolution of the thermodynamic relevant quantities, is a task that requires tight links among theoretical, experimental and numerical studies. The framework of the model here proposed, which operates a reduction of complexity on the nonlinear self-organizing plasma dynamics, allows in fact multiple validations of the current understanding of the tokamak micro-turbulence. The main outcomes of this work stem from the fundamental steps involved by the formulation of such a reduced transport model, namely: (1) the verification of the quasi-linear plasma response against the nonlinearly computed solution, (2) the improvement of the turbulent saturation model through an accurate validation of the nonlinear codes against the turbulence measurements, (3) the integration of the quasi-linear model within an integrated transport solver.
A Meshfree Quasi-Interpolation Method for Solving Burgers’ Equation
Directory of Open Access Journals (Sweden)
Mingzhu Li
2014-01-01
Full Text Available The main aim of this work is to consider a meshfree algorithm for solving Burgers’ equation with the quartic B-spline quasi-interpolation. Quasi-interpolation is very useful in the study of approximation theory and its applications, since it can yield solutions directly without the need to solve any linear system of equations and overcome the ill-conditioning problem resulting from using the B-spline as a global interpolant. The numerical scheme is presented, by using the derivative of the quasi-interpolation to approximate the spatial derivative of the dependent variable and a low order forward difference to approximate the time derivative of the dependent variable. Compared to other numerical methods, the main advantages of our scheme are higher accuracy and lower computational complexity. Meanwhile, the algorithm is very simple and easy to implement and the numerical experiments show that it is feasible and valid.
Quasi-universal properties of neutron star mergers
Bernuzzi, Sebastiano; Balmelli, Simone; Dietrich, Tim; Ujevic, Maximiliano
2014-01-01
Binary neutron star mergers are investigated using nonlinear 3+1 numerical relativity simulations and the analytical effective-one-body (EOB) model. The EOB model predicts quasi-universal relations between the mass-rescaled gravitational wave frequency and the binding energy at the moment of merger, and certain dimensionless binary tidal coupling constants depending on the stars Love numbers, compactnesses and the binary mass ratio. These relations are quasi-universal in the sense that, for a given value of the tidal coupling constant, they depend significantly neither on the equation of state nor on the mass ratio, though they do depend on stars spins. The spin dependence is approximately linear for small spins aligned with the orbital angular momentum. The quasi-universality is a property of the conservative dynamics, and emerges as the binary interaction becomes tidally dominated. This analytical prediction is qualitatively consistent with new, multi-orbit numerical relativity results for the relevant case...
Measurement of Muon Neutrino Quasi-Elastic Scattering on a Hydrocarbon Target at E_{\
Fiorentini, G A; Rodrigues, P A; Aliaga, L; Altinok, O; Bodek, A; Boehnlein, D; Bradford, R; Brooks, W K; Budd, H; Butkevich, A; Caicedo, D A M; Castromonte, C M; Christy, M E; Chvojka, J; da Motta, H; Damiani, D S; Danko, I; Datta, M; Day, M; DeMaat, R; Devan, J; Diaz, G A; Dytman, S A; Eberly, B; Edmondson, D A; Felix, J; Fields, L; Fitzpatrick, T; Gago, A M; Gallagher, H; Gobbi, B; Gran, R; Harris, D A; Higuera, A; Howley, I J; Hurtado, K; Jerkins, M; Kafka, T; Kanter, M O; Keppel, C; Kordosky, M; Krajeski, A H; Kulagin, S A; Le, T; Leister, A G; Maggi, G; Maher, E; Manly, S; Mann, W A; Marshall, C M; McFarland, K S; McGivern, C L; McGowan, A M; Mislivec, A; Morfin, J G; Mousseau, J; Naples, D; Nelson, J K; Niculescu, G; Niculescu, I; Ochoa, N; O'Connor, C D; Osta, J; Palomino, J L; Paolone, V; Park, J; Patrick, C E; Perdue, G N; Pena, C; Rakotondravohitra, L; Ransome, R D; Ray, H; Ren, L; Sassin, K E; Schellman, H; Schneider, R M; Schulte, E C; Sedita, P; Simon, C; Snider, F D; Snyder, M C; Sobczyk, J T; Salinas, C J Solano; Tagg, N; Tan, W; Tice, B G; Tzanakos, G; Velasquez, J P; Walding, J; Walton, T; Wolcott, J; Wolthuis, B A; Zavala, G; Zhang, D; Ziemer, B P
2013-01-01
We report a study of muon neutrino charged-current quasi-elastic events in the segmented scintillator inner tracker of the MINERvA experiment running in the NuMI neutrino beam at Fermilab. The events were selected by requiring a {\\mu}^- and low calorimetric recoil energy separated from the interaction vertex. We measure the flux-averaged differential cross-section, d{\\sigma}/dQ^2, and study the low energy particle content of the final state. Deviations are found between the measured d{\\sigma}/dQ^2 and the expectations of a model of independent nucleons in a relativistic Fermi gas. We also observe an excess of energy near the vertex consistent with multiple protons in the final state.
Extraction of structure functions for lepton-nucleus scattering in the quasi-elastic region
Kim, K. S.; Kim, Hungchong; Cheoun, Myung-Ki; So, W. Y.
2016-12-01
Within the framework of a relativistic single-particle model, we calculate inclusive electron-nucleus scattering by electromagnetic current, and neutrino-nucleus scattering by neutral and charged current in the quasi-elastic region. The longitudinal, the transverse, and the transverse-interference structure functions are extracted from the theoretical cross section by using the Rosenbluth separation method at fixed momentum transfer and scattering angle and then compared with each other from the viewpoint of these current interactions. The position of peak for the electron scattering shifts to higher energy transfer than that for the neutrino scattering. The axial and pseudoscalar terms turn out to play an important role in the neutrino-nucleus scattering.
Nuclear reactor transient analysis via a quasi-static kinetics Monte Carlo method
Jo, YuGwon; Cho, Bumhee; Cho, Nam Zin
2015-12-01
The predictor-corrector quasi-static (PCQS) method is applied to the Monte Carlo (MC) calculation for reactor transient analysis. To solve the transient fixed-source problem of the PCQS method, fission source iteration is used and a linear approximation of fission source distributions during a macro-time step is introduced to provide delayed neutron source. The conventional particle-tracking procedure is modified to solve the transient fixed-source problem via MC calculation. The PCQS method with MC calculation is compared with the direct time-dependent method of characteristics (MOC) on a TWIGL two-group problem for verification of the computer code. Then, the results on a continuous-energy problem are presented.
The properties and causes of rippling in quasi-perpendicular collisionless shock fronts
Directory of Open Access Journals (Sweden)
R. E. Lowe
Full Text Available The overall structure of quasi-perpendicular, high Mach number collisionless shocks is controlled to a large extent by ion reflection at the shock ramp. Departure from a strictly one-dimensional structure is indicated by simulation results showing that the surface of such shocks is rippled, with variations in the density and all field components. We present a detailed analysis of these shock ripples, using results from a two-dimensional hybrid (particle ions, electron fluid simulation. The process that generates the ripples is poorly understood, because the large gradients at the shock ramp make it difficult to identify instabilities. Our analysis reveals new features of the shock ripples, which suggest the presence of a surface wave mode dominating the shock normal magnetic field component of the ripples, as well as whistler waves excited by reflected ions.
Key words. Space plasma physics (numerical simulation studies; shock waves; waves and instabilities
Simulation of Quasi-Adiabatic Beam Capture into Acceleration at the Nuclotron
Volkov, V I; Issinsky, I B; Kovalenko, A D
2003-01-01
The routine RF system being used at the Nuclotron allows one to inject the beam at ramping magnetic field with following acceleration at constant amplitude of accelerating voltage. At these conditions at least a half of the particles circulating in the vacuum chamber after injection is not captured in longitudinal acceptance. At the same time vacuum chamber sizes permit to extend the momentum spread of the beam enough to make gymnastic with it inside the stable zone of longitudinal phase space on the flat magnetic field at injection. A quasi-adiabatic capture was considered for increasing the Nuclotron beam intensity. Simulation of such a kind of process with subsequent acceleration was performed. It was shown that in this case it is possible to capture and accelerate up to 100 % of the injected beam.
Nuclear reactor transient analysis via a quasi-static kinetics Monte Carlo method
Energy Technology Data Exchange (ETDEWEB)
Jo, YuGwon; Cho, Bumhee; Cho, Nam Zin, E-mail: nzcho@kaist.ac.kr [Korea Advanced Institute of Science and Technology 291 Daehak-ro, Yuseong-gu, Daejeon, Korea 305-701 (Korea, Republic of)
2015-12-31
The predictor-corrector quasi-static (PCQS) method is applied to the Monte Carlo (MC) calculation for reactor transient analysis. To solve the transient fixed-source problem of the PCQS method, fission source iteration is used and a linear approximation of fission source distributions during a macro-time step is introduced to provide delayed neutron source. The conventional particle-tracking procedure is modified to solve the transient fixed-source problem via MC calculation. The PCQS method with MC calculation is compared with the direct time-dependent method of characteristics (MOC) on a TWIGL two-group problem for verification of the computer code. Then, the results on a continuous-energy problem are presented.
Indian Academy of Sciences (India)
M Sivanantham; B V R Tata
2010-12-01
Polyacrylamide (PAAm) hydrogels immersed in water and aqueous NaCl solutions were investigated for their structure and dynamics using static and quasi-elastic laser light scattering (QELS) techniques. Ensemble-averaged electric field correlation function (, ) obtained from the non-ergodic analysis of intensity-autocorrelation function for PAAm gel immersed in water and in 5 M NaCl showed an exponential decay to a plateau with an initial decay followed by saturation at long times. The value of the plateau was found to depend on NaCl concentration and was higher than that of water. Collective diffusion coefficient, , of the polymer network of the hydrogel immersed in water and in different concentrations of NaCl was determined by analysing (, ). The measured diffusion coefficient showed linear decrease with increase in concentration of NaCl. The characteristic network parameters were obtained by analyzing (, ) with harmonically bound Brownian particle model and from static light scattering studies.
A coupling model for quasi-normal modes of photonic resonators
Vial, Benjamin; Hao, Yang
2016-11-01
We develop a model for the coupling of quasi-normal modes in open photonic systems consisting of two resonators. By expressing the modes of the coupled system as a linear combination of the modes of the individual particles, we obtain a generalized eigenvalue problem involving small size dense matrices. We apply this technique to dielectric rod dimmer of rectangular cross section for transverse electric polarization in a two-dimensional setup. The results of our model show excellent agreement with full wave finite element simulations. We provide a convergence analysis, and a simplified model with a few modes to study the influence of the relative position of the two resonators. This model provides interesting physical insights on the coupling scheme at stake in such systems and pave the way for systematic and efficient design and optimization of resonances in more complicated systems, for applications including sensing, antennae and spectral filtering.
A coupling model for quasi-normal modes of photonic resonators
Vial, Benjamin
2016-01-01
We develop a model for the coupling of quasi-normal modes in open photonic systems consisting of two resonators. By expressing the modes of the coupled system as a linear combination of the modes of the individual particles, we obtain a generalized eigenvalue problem involving small size dense matrices. We apply this technique to a 2D problem of a high index rod dimmer of rectangular cross section for Transverse Electric (TE) polarization. The results of our model are compared with full-wave finite element simulations and show a good agreement for the four lowest eigenvalues by taking into account the two lowest eigenfrequencies of the isolated rods. This model provides interesting physical insights on the coupling scheme at stake in such systems and pave the way for the design and optimization of resonances in more complicated systems, including the engineering of metamaterial unit cells.
Constant-temperature level densities in the quasi-continuum of Th and U isotopes
Guttormsen, M; Wilson, J N; Aiche, M; Bernstein, L A; Ducasse, Q; Giacoppo, F; Goergen, A; Gunsing, F; Hagen, T W; Larsen, A C; Lebois, M; Leniau, B; Renstroem, T; Rose, S J; Siem, S; Tornyi, T; Tveten, G M; Wiedeking, M
2013-01-01
Particle-gamma coincidences have been measured to obtain gamma-ray spectra as a function of excitation energy for 231-233Th and 237-239U. The level densities, which were extracted using the Oslo method, show a constant temperature behavior. The isotopes display very similar temperatures in the quasi-continuum, however, the even-odd isotopes reveal a constant entropy increase Delta S compared to their even-even neighbors. The entropy excess depends on available orbitals for the last unpaired valence neutron of the heated nuclear system. Also, experimental microcanonical temperature and heat capacity have been extracted. Several poles in the heat capacity curve support the idea that an almost continuous melting of Cooper pairs is responsible for the constant-temperature behavior.
Numerical simulation of flow fields and particle trajectories
DEFF Research Database (Denmark)
Mayer, Stefan
2000-01-01
A model describing the ciliary driven flow and motion of suspended particles in downstream suspension feeders is developed. The quasi-steady Stokes equations for creeping flow are solved numerically in an unbounded fluid domain around cylindrical bodies using a boundary integral formulation...... region close to the driving ciliary bands and a steady region covering the remaining fluid domain. The size of the unsteady region appears to be comparable to the metachronal wavelength of the ciliary band. A systematic investigation is performed of trajectories of infinitely small (fluid) particles...... in the simulated unsteady ciliary driven flow. A fraction of particles appear to follow trajectories, that resemble experimentally observed particle capture events in the downstream feeding system of the polycheate Sabella penicillus, indicating that particles can be captured by ciliary systems without mechanical...
Determining pitch-angle diffusion coefficients from test particle simulations
Ivascenko, A; Spanier, F; Vainio, R
2016-01-01
Transport and acceleration of charged particles in turbulent media is a topic of great interest in space physics and interstellar astrophysics. These processes are dominated by the scattering of particles off magnetic irregularities. The scattering process itself is usually described by small-angle scattering with the pitch-angle coefficient $D_{\\mu\\mu}$ playing a major role. Since the diffusion coefficient $D_{\\mu\\mu}$ can be determined analytically only for the approximation of quasi-linear theory, the determination of this coefficient from numerical simulations has, therefore, become more important. So far these simulations yield particle tracks for small-scale scattering, which can then be interpreted using the running diffusion coefficients. This method has a limited range of validity. This paper presents two new methods that allow for the calculation of the pitch-angle diffusion coefficient from numerical simulations. These methods no longer analyse particle trajectories, but the change of particle dist...
Acoustic radiation force on a rigid elliptical cylinder in plane (quasi)standing waves
Energy Technology Data Exchange (ETDEWEB)
Mitri, F. G., E-mail: F.G.Mitri@ieee.org [Chevron, Area 52 Technology–ETC, Santa Fe, New Mexico 87508 (United States)
2015-12-07
The acoustic radiation force on a 2D elliptical (non-circular) cylinder centered on the axis of wave propagation of plane quasi-standing and standing waves is derived, based on the partial-wave series expansion (PWSE) method in cylindrical coordinates. A non-dimensional acoustic radiation force function, which is the radiation force per unit length, per characteristic energy density and per unit cross-sectional surface of the ellipse, is defined in terms of the scattering coefficients that are determined by applying the Neumann boundary condition for an immovable surface. A system of linear equations involving a single numerical integration procedure is solved by matrix inversion. Numerical simulations showing the transition from the quasi-standing to the (equi-amplitude) standing wave behaviour are performed with particular emphasis on the aspect ratio a/b, where a and b are the ellipse semi-axes, as well as the dimensionless size parameter kb (where k is the wavenumber), without the restriction to a particular range of frequencies. It is found that at high kb values > 1, the radiation force per length with broadside incidence is larger, whereas the opposite situation occurs in the long-wavelength limit (i.e., kb < 1). The results are particularly relevant in acoustic levitation of elliptical cylinders, the acoustic stabilization of liquid columns in a host medium, acousto-fluidics devices, and other particle dynamics applications to name a few. Moreover, the formalism presented here may be effectively applied to compute the acoustic radiation force on other 2D surfaces of arbitrary shape such as super-ellipses, Chebyshev cylindrical particles, or other non-circular geometries.
HBV subgenotype misclassification expands quasi-subgenotype A3.
Pourkarim, M R; Amini-Bavil-Olyaee, S; Lemey, P; Maes, P; Van Ranst, M
2011-06-01
Recently, we proposed a new classification for 'subgenotype A' of hepatitis B virus (HBV), in which the novel 'quasi-subgenotype A3' group comprising HBV 'subgenotype A3', 'tentative A4', and A5 was introduced. Newly 'Tentative subgenotype A7' strains from Cameroon were introduced by Hubschen et al. However, our meticulous phylogenetic analysis demonstrated that these isolates should also be classified into 'quasi-subgenotype A3'. Such misclassification can be avoided by following established principles for HBV subgenotyping. Moreover, their close evolutionary relationship with A3 highlights our hypothesis that geographical origin may be an important factor in further classification of HBV subgenotypes.
Hydrodynamic turbulence in quasi-Keplerian rotating flows
Shi, Liang; Hof, Björn; Rampp, Markus; Avila, Marc
2017-04-01
We report a direct-numerical-simulation study of the Taylor-Couette flow in the quasi-Keplerian regime at shear Reynolds numbers up to O (105) . Quasi-Keplerian rotating flow has been investigated for decades as a simplified model system to study the origin of turbulence in accretion disks that is not fully understood. The flow in this study is axially periodic and thus the experimental end-wall effects on the stability of the flow are avoided. Using optimal linear perturbations as initial conditions, our simulations find no sustained turbulence: the strong initial perturbations distort the velocity profile and trigger turbulence that eventually decays.
Quasi-optical attenuators for ALMA band 10 receiver
Gonzalez, A.; Fujii, Y.; Kaneko, K.; Uzawa, Y.
2011-12-01
Simple quasi-optical attenuators based on beam truncation have been designed, fabricated and tried on ALMA band 10 receivers (787-950 GHz) with optimal results. The design is based on physical-optics simulations considering effects of diffraction. The use of these attenuators allows flexibility in the design of the local oscillator (LO) quasi-optical injection scheme depending on the specific performance of components for each of the 73 ALMA band 10 receivers. In particular, they have proven very effective to keep system noise within the stringent ALMA requirements (230 K at 80% of 787-950 GHz band).
Total variation approximation for quasi-equilibrium distributions
Barbour, A D
2010-01-01
Quasi-stationary distributions, as discussed by Darroch & Seneta (1965), have been used in biology to describe the steady state behaviour of population models which, while eventually certain to become extinct, nevertheless maintain an apparent stochastic equilibrium for long periods. These distributions have some drawbacks: they need not exist, nor be unique, and their calculation can present problems. In this paper, we give biologically plausible conditions under which the quasi-stationary distribution is unique, and can be closely approximated by distributions that are simple to compute.
Quasi-single-mode homogeneous 31-core fibre
DEFF Research Database (Denmark)
Sasaki, Y.; Saitoh, S.; Amma, Y.
2015-01-01
A homogeneous 31-core fibre with a cladding diameter of 230 μm for quasi-single-mode transmission is designed and fabricated. LP01-crosstalk of -38.4 dB/11 km at 1550 nm is achieved by using few-mode trench-assisted cores.......A homogeneous 31-core fibre with a cladding diameter of 230 μm for quasi-single-mode transmission is designed and fabricated. LP01-crosstalk of -38.4 dB/11 km at 1550 nm is achieved by using few-mode trench-assisted cores....
Hydromagnetic quasi-geostrophic modes in rapidly rotating planetary cores
DEFF Research Database (Denmark)
Canet, E.; Finlay, Chris; Fournier, A.
2014-01-01
The core of a terrestrial-type planet consists of a spherical shell of rapidly rotating, electrically conducting, fluid. Such a body supports two distinct classes of quasi-geostrophic (QG) eigenmodes: fast, primarily hydrodynamic, inertial modes with period related to the rotation time scale......, or shorter than, their oscillation time scale.Based on our analysis, we expect Mercury to be in a regime where the slow magnetic modes are of quasi-free decay type. Earth and possibly Ganymede, with their larger Elsasser numbers, may possess slow modes that are in the transition regime of weak diffusion...
Quasi-Monte Carlo methods for the Heston model
Jan Baldeaux; Dale Roberts
2012-01-01
In this paper, we discuss the application of quasi-Monte Carlo methods to the Heston model. We base our algorithms on the Broadie-Kaya algorithm, an exact simulation scheme for the Heston model. As the joint transition densities are not available in closed-form, the Linear Transformation method due to Imai and Tan, a popular and widely applicable method to improve the effectiveness of quasi-Monte Carlo methods, cannot be employed in the context of path-dependent options when the underlying pr...
Electron-phonon coupling in quasi free-standing graphene
DEFF Research Database (Denmark)
Christian Johannsen, Jens; Ulstrup, Søren; Bianchi, Marco
2013-01-01
Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many......-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both...
Quasi-static Deployment Simulation for Deployable Space Truss Structures
Institute of Scientific and Technical Information of China (English)
陈务军; 付功义; 何艳丽; 董石麟
2004-01-01
A new method was proposed for quasi-static deployment analysis of deployable space truss structures. The structure is assumed a rigid assembly, whose constraints are classified as three categories:rigid member constraint, joint-attached kinematic constraint and boundary constraint. And their geometric constraint equations and derivative matrices are formulated. The basis of the null space and M-P inverse of the geometric constraint matrix are employed to determine the solution for quasi-static deployment analysis. The influence introduced by higher terms of constraints is evaluated subsequently. The numerical tests show that the new method is efficient.
Quasi-dynamical symmetries in the backbending of chromium isotopes
Herrera, Raul A
2016-01-01
We examine the well-known backbending, or abrupt change in the moment of inertia along the yrast line, in $^{48,49,50}$Cr by decomposing configuration-interaction shell-model wavefunctions into group irreps, using the subgroups $L$ (total orbital angular momentum) and $S$ (total spin) of SU(2), and the groups SU(3) and SU(4). We see strong signatures of quasi-dynamical symmetries--the same or similar decomposition across members of a band--below the backbending, while quasi-dynamical symmetry is weaker above the bandbending.
Pressure-driven reconnection and quasi periodical oscillations in plasmas
Paccagnella, R.
2014-03-01
This paper presents a model for an ohmically heated plasma in which a feedback exists between thermal conduction and transport, on one side, and the magneto-hydro-dynamical stability of the system, on the other side. In presence of a reconnection threshold for the magnetic field, a variety of periodical or quasi periodical oscillations for the physical quantities describing the system are evidenced. The model is employed to interpret the observed quasi periodical oscillations of electron temperature and perturbed magnetic field around the so called "Single Helical" state in the reversed field pinch, but its relevance for other periodical phenomena observed in magnetic confinement systems, especially in tokamaks, is suggested.
Quasi-coherent Hecke category and Demazure descent
DEFF Research Database (Denmark)
Arkhipov, Sergey; Kanstrup, Tina
2015-01-01
Let G be a reductive algebraic group with a Borel subgroup B. We define the quasi-coherent Hecke category for the pair (G,B). For any regular Noetherian G- scheme X we construct a monoidal action of the Hecke category on the derived category of B-equivariant quasi-coherent sheaves on X. Using...... the action we define the Demazure Descent Data on the latter category and prove that the Descent category is equivalent to the derived category of G-equivariant sheaves on X....
A note on extremal quasi-conformal mappings
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
An extremal quasi-conformal mapping f of a domain D is said to be of non-landslide type if the set Ef(δ):= {z∈D:|μf(z)|≤||μ|| ∞ -δ} has no interior points for any δ > 0. In this paper,we construct a quasi-conformal mapping f of the unit disc D such that its Teichmu¨ller equivalence class [f] contains infinitely many extremal mappings of non-landslide type. The relation between extremal mappings of non-landslide type and locally extremal mappings is also discussed.
A note on unibasic spaces and transitive quasi-proximities
Adalberto García-Máynez; Adolfo Pimienta Acosta
2017-01-01
[EN] In this paper we prove there is a bijection between the set of all annular bases of a topological spaces $(X,\\tau)$ and the set of all transitive quasi-proximities on $X$ inducing $\\tau$.We establish some properties of those topological spaces $(X,\\tau)$ which imply that $\\tau$ is the only annular basis García-Máynez, A.; Pimienta Acosta, A. (2017). A note on unibasic spaces and transitive quasi-proximities. Applied General Topology. 18(1):23-30. doi:10.4995/agt.2017.4092. 23 30...
Covariant Hamiltonian boundary term: Reference and quasi-local quantities
Sun, Gang; Liu, Jian-Liang; Nester, James M
2016-01-01
The Hamiltonian for dynamic geometry generates the evolution of a spatial region along a vector field. It includes a boundary term which determines both the value of the Hamiltonian and the boundary conditions. The value gives the quasi-local quantities: energy-momentum, angular-momentum and center-of-mass. The boundary term depends not only on the dynamical variables but also on their reference values; the latter determine the ground state (having vanishing quasi-local quantities). For our preferred boundary term for Einstein's GR we propose 4D isometric matching and extremizing the energy to determine the reference metric and connection values.
Quasi-Normal Modes and Gravitational Wave Astronomy
Ferrari, V
2007-01-01
We review the main results obtained in the literature on quasi-normal modes of compact stars and black holes, in the light of recent exciting developments of gravitational wave detectors. Quasi-normal modes are a fundamental feature of the gravitational signal emitted by compact objects in many astrophysical processes; we will show that their eigenfrequencies encode interesting information on the nature and on the inner structure of the emitting source and we will discuss whether we are ready for a gravitational wave asteroseismology.
Electron-phonon coupling in quasi free-standing graphene
DEFF Research Database (Denmark)
Christian Johannsen, Jens; Ulstrup, Søren; Bianchi, Marco;
2013-01-01
Quasi free-standing monolayer graphene can be produced by intercalating species like oxygen or hydrogen between epitaxial graphene and the substrate crystal. If the graphene is indeed decoupled from the substrate, one would expect the observation of a similar electronic dispersion and many......-body effects, irrespective of the substrate and the material used to achieve the decoupling. Here we investigate the electron-phonon coupling in two different types of quasi free-standing monolayer graphene: decoupled from SiC via hydrogen intercalation and decoupled from Ir via oxygen intercalation. Both...
Nonlinear dynamic analysis of quasi-symmetric anisotropic structures
Noor, Ahmed K.; Peters, Jeanne M.
1987-01-01
An efficient computational method for the nonlinear dynamic analysis of quasi-symmetric anisotropic structures is proposed. The application of mixed models simplifies the analytical development and improves the accuracy of the response predictions, and operator splitting allows the reduction of the analysis model of the quasi-symmetric structure to that of the corresponding symmetric structure. The preconditoned conjugate gradient provides a stable and effective technique for generating the unsymmetric response of the structure as the sum of a symmetrized response plus correction modes. The effectiveness of the strategy is demonstrated with the example of a laminated anisotropic shallow shell of quadrilateral planform subjected to uniform normal loading.
Restricted and quasi-toral restricted Lie-Rinehart algebras
Directory of Open Access Journals (Sweden)
Sun Bing
2015-09-01
Full Text Available In this paper, we introduce the definition of restrictable Lie-Rinehart algebras, the concept of restrictability is by far more tractable than that of a restricted Lie-Rinehart algebra. Moreover, we obtain some properties of p-mappings and restrictable Lie-Rinehart algebras. Finally, we give some sufficient conditions for the commutativity of quasi-toral restricted Lie-Rinehart algebras and study how a quasi-toral restricted Lie-Rinehart algebra with zero center and of minimal dimension should be.
Quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei
Kovalchuk, V I
2016-01-01
The observed cross sections of quasi-elastic scattering of 6He, 7Be, and 8B nuclei by 12C nuclei are described within the framework of the diffraction nuclear model and the model of nucleus-nucleus scattering in the high-energy approximation with a double folding potential, for intermediate energies of the incident particles. The calculations make use of realistic distributions of nucleon densities and take account of the Coulomb interaction and inelastic scattering with excitation of low-lying collective states of the target.
Composite Vector Particles in External Electromagnetic Fields
Davoudi, Zohreh
2015-01-01
Lattice quantum chromodynamics (QCD) studies of electromagnetic properties of hadrons and light nuclei, such as magnetic moments and polarizabilities, have proven successful with the use of background field methods. With an implementation of nonuniform background electromagnetic fields, properties such as charge radii and higher electromagnetic multipole moments (for states of higher spin) can be additionally obtained. This can be achieved by matching lattice QCD calculations to a corresponding low-energy effective theory that describes the static and quasi-static response of hadrons and nuclei to weak external fields. With particular interest in the case of vector mesons and spin-1 nuclei such as the deuteron, we present an effective field theory of spin-1 particles coupled to external electromagnetic fields. To constrain the charge radius and the electric quadrupole moment of the composite spin-1 field, the single-particle Green's functions in a linearly varying electric field in space are obtained within t...
Indian Academy of Sciences (India)
A. Shanmugaraju; S. Umapathy
2000-09-01
A set of 21 solar type II radio bursts observed using Hiraiso radio spectrograph have been analysed to study the direction of propagation of coronal shocks. Α simple analysis is carried out to find the approximate angle between the shock normal and magnetic field by solving the Rankine-Hugoniot MHD relation with assumption of Alfven speed and plasma beta. From this analysis, it is suggested that both quasi-parallel shocks (favourable) and quasi-perpendicular shocks can generate type II bursts depending upon the circumstances of the corona.
Zhu, Minjie; Scott, Michael H.
2016-07-01
Accurate and efficient response sensitivities for fluid-structure interaction (FSI) simulations are important for assessing the uncertain response of coastal and off-shore structures to hydrodynamic loading. To compute gradients efficiently via the direct differentiation method (DDM) for the fully incompressible fluid formulation, approximations of the sensitivity equations are necessary, leading to inaccuracies of the computed gradients when the geometry of the fluid mesh changes rapidly between successive time steps or the fluid viscosity is nonzero. To maintain accuracy of the sensitivity computations, a quasi-incompressible fluid is assumed for the response analysis of FSI using the particle finite element method and DDM is applied to this formulation, resulting in linearized equations for the response sensitivity that are consistent with those used to compute the response. Both the response and the response sensitivity can be solved using the same unified fractional step method. FSI simulations show that although the response using the quasi-incompressible and incompressible fluid formulations is similar, only the quasi-incompressible approach gives accurate response sensitivity for viscous, turbulent flows regardless of time step size.
Study of particle swarm optimization particle trajectories
CSIR Research Space (South Africa)
Van den Bergh, F
2006-01-01
Full Text Available provides a formal proof that each particle converges to a stable point. An empirical analysis of multidimensional stochastic particles is also presented. Experimental results are provided to support the conclusions drawn from the theoretical findings...
Quasi-harmonic calculations of the isotope effect in diffusion
Energy Technology Data Exchange (ETDEWEB)
Harding, J.H.
1986-11-10
It is shown how the kinetic energy factor for isotope diffusion may be calculated within the quasi-harmonic approximation using methods devised to calculate the vibrational contribution to defect entropies. The results are compared with experiment in the cases of CoO and NiO and good agreement found.
Quasi-periodic oscillations from Rossby Wave Instability
Vincent, F H; Meheut, H; Paumard, T; Torok, G; Wildner, M
2013-01-01
We study the Rossby wave instability model of high-frequency quasi-periodic oscillations (QPO) of microquasars. We show ray-traced light curves of QPO within this model and discuss perspectives of distinguishing alternative QPO models with the future Large Observatory For X-ray Timing (LOFT) observations.
QUASI-PML FOR WAVES IN CYLINDRICAL COORDINATES. (R825225)
We prove that the straightforward extension of Berenger's original perfectly matched layer (PML) is not reflectionless at a cylindrical interface in the continuum limit. A quasi-PLM is developed as an absorbing boundary condition (ABC) for the finite-difference time-domain method...
Scale ratios in decaying quasi-geographic turbulence
Energy Technology Data Exchange (ETDEWEB)
Dritschel, G. [St. Andrews Univ., St. Andrews, Scotland (United Kingdom). School of Mathematics
1999-12-01
The study re-examines quasi-geographic turbulence in vertically periodic boundaries, at times well before two-dimensional vortices might emerge. It has been focused specifically on the characteristic scale ratio of structures, and how it compares to that found for rigid, isothermal boundaries.
Current-Voltage Characteristics of Quasi-One-Dimensional Superconductors
DEFF Research Database (Denmark)
Vodolazov, D.Y.; Peeters, F.M.; Piraux, L.
2003-01-01
The current-voltage (I-V) characteristics of quasi-one-dimensional superconductors were discussed. The I-V characteristics exhibited an unusual S behavior. The dynamics of superconducting condensate and the existence of two different critical currents resulted in such an unusual behavior....
Origin of Quasi-decadal North Atlantic Oscillation Variability
Reintges, Annika; Latif, Mojib; Park, Wonsun
2015-04-01
The North Atlantic Oscillation (NAO) is the leading mode of internal atmospheric variability in the North Atlantic sector. It depicts significant quasi-decadal variability that is well documented, but the underlying mechanism is still under discussion. Other quantities in the North Atlantic sector such as sea surface temperature (SST) exhibit variability on a similar timescale. Here we present results from a global climate model which simulates the quasi-decadal NAO and North Atlantic SST variability consistent with observations. The quasi-decadal NAO variability is suggested to originate from large-scale air-sea interactions, where the Atlantic Meridional Overturning Circulation (AMOC) basically sets the timescale. Wind-driven ocean circulation changes provide a fast positive feedback on North Atlantic SST through anomalous Ekman currents and the establishment of an "intergyre" gyre. A delayed negative feedback on SST is accomplished through surface heat flux-driven changes of the AMOC and associated heat transport. The results stress the importance of both wind-induced and thermohaline-induced changes in the ocean circulation for quasi-decadal climate variability in the North Atlantic sector.
On some perturbation techniques for quasi-linear parabolic equations
Directory of Open Access Journals (Sweden)
Igor Malyshev
1990-01-01
Full Text Available We study a nonhomogeneous quasi-linear parabolic equation and introduce a method that allows us to find the solution of a nonlinear boundary value problem in explicit form. This task is accomplished by perturbing the original equation with a source function, which is then found as a solution of some nonlinear operator equation.
Quasi Y-Source Boost DC-DC Converter
DEFF Research Database (Denmark)
Siwakoti, Yam P.; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
A new topology called “quasi-Y-source impedance network” is presented in this paper. It inherits all the advantages of the original Y-source network. In addition, the new topology draws continuous current from the source which is required for many renewable sources. It also has dc-current-blockin...
Quasi-Y-Source Boost DC–DC Converter
DEFF Research Database (Denmark)
Siwakoti, Yam Prasad; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
In this letter, a new topology called “quasi-Y-source dc-dc converter” is presented. It inherits all the advantages of the original Y-source converter. In addition, the new topology draws a continuous current from the source, which is definitely more appropriate for most renewable sources. It als...
Dynamics of Shape Fluctuations of Quasi-spherical Vesicles Revisited
DEFF Research Database (Denmark)
Miao, L.; Lomholt, Michael Andersen; Kleis, J.
2002-01-01
In this paper, the dynamics of spontaneous shape fluctuations of a single, giant quasi-spherical vesicle formed from a single lipid species is revisited theoretically. A coherent physical theory for the dynamics is developed based on a number of fundamental principles and considerations, and a sy...
Design of a Quasi-Hemispherical UWB Antenna
DEFF Research Database (Denmark)
Zhekov, Stanislav Stefanov; Tatomirescu, Alexandru; Franek, Ondrej;
2016-01-01
This paper proposes a design of three-dimensional antenna for ultrawideband applications. The antenna has dimensions of 58 mm x 58 mm x 76.5 mm and is composed of two identical arms. Each arm consists of a hollow quasi-hemisphere and an inner for it tube. In the simulation, a 50 Ω coaxial cable...
Dirac oscillators and quasi-exactly solvable operators
Brihaye, Y
2005-01-01
The Dirac equation is considered in the background of potentials of several types, namely scalar and vector-potentials as well as "Dirac-oscillator" potential or some of its generalisations. We investigate the radial Dirac equation within a quite general spherically symmetric form for these potentials and we analyse some exactly and quasi exactly solvable properties of the underlying matricial linear operators.
QUASI-EQUILIBRIA IN MARKETS WITH NON-CONVEX PREFERENCES.
An upper bound is placed on social divergence from general equilibrium , due to non-convexity of the traders’ preference relations. Existence and significance of certain quasi-equilibria are investigated. If there is a sufficiently large number of traders in the market, the existence of a configuration arbitrarily close to equilibrium is demonstrated. (Author)
Constrained Hartree-Fock and quasi-spin projection
Cambiaggio, M. C.; Plastino, A.; Szybisz, L.
1980-08-01
The constrained Hartree-Fock approach of Elliott and Evans is studied in detail with reference to two quasi-spin models, and their predictions compared with those arising from a projection method. It is found that the new approach works fairly well, although limitations to its applicability are encountered.
Second Noether theorem for quasi-Noether systems
Rosenhaus, V.; Shankar, R.
2016-04-01
Quasi-Noether differential systems are more general than variational systems and are quite common in mathematical physics. They include practically all differential systems of interest, at least those that have conservation laws. In this paper, we discuss quasi-Noether systems that possess infinite-dimensional (infinite) symmetries involving arbitrary functions of independent variables. For quasi-Noether systems admitting infinite symmetries with arbitrary functions of all independent variables, we state and prove an extension of the second Noether theorem. In addition, we prove that infinite sets of conservation laws involving arbitrary functions of all independent variables are trivial and that the associated differential system is under-determined. We discuss infinite symmetries and infinite conservation laws of two important examples of non-variational quasi-Noether systems: the incompressible Euler equations and the Navier-Stokes equations in vorticity formulation, and we show that the infinite sets of conservation laws involving arbitrary functions of all independent variables are trivial. We also analyze infinite symmetries involving arbitrary functions of not all independent variables, prove that the fluxes of conservation laws in these cases are total divergences on solutions, and demonstrate examples of this situation.
Hawking-Hayward quasi-local energy under conformal transformations
Prain, Angus; Faraoni, Valerio; Lapierre-Léonard, Marianne
2015-01-01
We derive a formula describing the transformation of the Hawking-Hayward quasi-local energy under a conformal rescaling of the spacetime metric. A known formula for the transformation of the Misner-Sharp-Hernandez mass is recovered as a special case.
Validating a quasi-linear transport model versus nonlinear simulations
Casati, A.; Bourdelle, C.; Garbet, X.; Imbeaux, F.; Candy, J.; Clairet, F.; Dif-Pradalier, G.; Falchetto, G.; Gerbaud, T.; Grandgirard, V.; Gürcan, Ö. D.; Hennequin, P.; Kinsey, J.; Ottaviani, M.; Sabot, R.; Sarazin, Y.; Vermare, L.; Waltz, R. E.
2009-08-01
In order to gain reliable predictions on turbulent fluxes in tokamak plasmas, physics based transport models are required. Nonlinear gyrokinetic electromagnetic simulations for all species are still too costly in terms of computing time. On the other hand, interestingly, the quasi-linear approximation seems to retain the relevant physics for fairly reproducing both experimental results and nonlinear gyrokinetic simulations. Quasi-linear fluxes are made of two parts: (1) the quasi-linear response of the transported quantities and (2) the saturated fluctuating electrostatic potential. The first one is shown to follow well nonlinear numerical predictions; the second one is based on both nonlinear simulations and turbulence measurements. The resulting quasi-linear fluxes computed by QuaLiKiz (Bourdelle et al 2007 Phys. Plasmas 14 112501) are shown to agree with the nonlinear predictions when varying various dimensionless parameters, such as the temperature gradients, the ion to electron temperature ratio, the dimensionless collisionality, the effective charge and ranging from ion temperature gradient to trapped electron modes turbulence.
Implementation of the quasi-static method for neutron transport
Energy Technology Data Exchange (ETDEWEB)
Alcaro, Fabio; Dulla, Sandra; Ravetto, Piero, E-mail: fabio.alcaro@polito.it, E-mail: sandra.dulla@polito.it, E-mail: piero.ravetto@polito.it [Dipartimento di Energetica, Politecnico di Torino (Italy); Le Tellier, Romain; Suteau, Christophe, E-mail: romain.le-tellier@cea.fr, E-mail: christophe.suteau@cea.fr [CEA, DEN, DER/SPRC/LEPh, Cadarache, Saint Paul-lez-Durance (France)
2011-07-01
The study of the dynamic behavior of next generation nuclear reactors is a fundamental aspect for safety and reliability assessments. Despite the growing performances of modern computers, the full solution of the neutron Boltzmann equation in the time domain is still an impracticable task, thus several approximate dynamic models have been proposed for the simulation of nuclear reactor transients; the quasi-static method represents the standard tool currently adopted for the space-time solution of neutron transport problems. All the practical applications of this method that have been proposed contain a major limit, consisting in the use of isotropic quantities, such as scalar fluxes and isotropic external neutron sources, being the only data structures available in most deterministic transport codes. The loss of the angular information produces both inaccuracies in the solution of the kinetic model and the inconsistency of the quasi-static method itself. The present paper is devoted to the implementation of a consistent quasi-static method. The computational platform developed by CEA in Cadarache has been used for the creation of a kinetic package to be coupled with the existing SNATCH solver, a discrete-ordinate multi-dimensional neutron transport solver, employed for the solution of the steady-state Boltzmann equation. The work aims at highlighting the effects of the angular treatment of the neutron flux on the transient analysis, comparing the results with those produced by the previous implementations of the quasi-static method. (author)
Quasi-one-dimensional intermittent flux behavior in superconducting films
DEFF Research Database (Denmark)
Qviller, A. J.; Yurchenko, V. V.; Galperin, Y. M.
2012-01-01
. The intermittent behavior shows no threshold value in the applied field, in contrast to conventional flux jumping. The results strongly suggest that the quasi-one-dimensional flux jumps are of a different nature than the thermomagnetic dendritic (branching) avalanches that are commonly found in superconducting...
Quasi-elastic nuclear scattering at high energies
Cucinotta, Francis A.; Townsend, Lawrence W.; Wilson, John W.
1992-01-01
The quasi-elastic scattering of two nuclei is considered in the high-energy optical model. Energy loss and momentum transfer spectra for projectile ions are evaluated in terms of an inelastic multiple-scattering series corresponding to multiple knockout of target nucleons. The leading-order correction to the coherent projectile approximation is evaluated. Calculations are compared with experiments.
Nonhomogeneous Variational Problems and Quasi-Minimizers on Metric Spaces
Gong, Jasun; Parviainen, Mikko
2010-01-01
We show that quasi-minimizers of non-homogeneous energy functionals on metric measure spaces are locally H\\"older continuous and satisfy the Harnack inequality. We assume that the spaces are doubling and support a Poincar\\'e inequality. The proof is based on the De Giorgi method, combined with the "expansion of positivity" technique.
Quasi-classical dynamics of interacting Bose condensates
Salgueiro, A N; Sampaio, M D; De Toledo di Piza, A F R
1998-01-01
The dynamics of the composition of uniform Bose condensates involving two species capable of reciprocal interconversion is treated in terms of a collective quasi-spin model. This collective model quickly reduces to classical form towards the thermodynamic limit. Quantum solutions are easily obtained numerically short of this limit which give insight into the dynamically relevant correlation processes.
A note on unibasic spaces and transitive quasi-proximities
Directory of Open Access Journals (Sweden)
Adalberto García-Máynez
2017-04-01
Full Text Available In this paper we prove there is a bijection between the set of all annular bases of a topological spaces $(X,\\tau$ and the set of all transitive quasi-proximities on $X$ inducing $\\tau$. We establish some properties of those topological spaces $(X,\\tau$ which imply that $\\tau$ is the only annular basis
A Robin Problem for Quasi-linear System
Institute of Scientific and Technical Information of China (English)
0UYANGCheng
2004-01-01
In this paper, a Robin problem for quasi-linear system is considered. Under the appropriate assumptions, the existence of solution for the problem is proved and the asymptotic behavior of the solution is studied using the theory of differential inequalities.
Quasi-Elastic Scattering in MINERvA
McFarland, Kevin S
2011-01-01
Determination of the quasi-elastic scattering cross-section over a broad range of neutrino energies, nuclear targets and Q^2 is a primary goal of the MINERvA experiment. We present preliminary comparisons of data and simulation in a sample rich in anti-{\
Interpretation of Quasi-Isothermal Thermogravimetric Weight Curves
DEFF Research Database (Denmark)
Sørensen, Ole Toft
1979-01-01
Quasi-isothermal analysis (QIA) is a very useful technique. Compared to conventional non-isothermal thermogravimetry, close-lying reactions can easily be separated by use of this method and kinetic data can be obtained for each intermediate reaction in a single run. This paper discusses the shape...
Thermal undulations of quasi-spherical vesicles stabilized by gravity
DEFF Research Database (Denmark)
Henriksen, Jonas Rosager; Ipsen, John Hjorth
2002-01-01
The classical treatment of quasi-spherical vesicle undulations has, in the present work, been reviewed and extended to systems, which are affected by a gravitational field caused by a density difference across the membrane. The effects have been studied by the use of perturbation theory leading...
Quasi-elastic Charm Production In Neutrino-nucleon Scattering
Bischofberger, M
2005-01-01
A study of quasi elastic charm production in charged current neutrino-nucleon scattering is presented. A sample of about 1.3 million interactions recorded with the NOMAD detector in the CERN SPS wide band neutrino beam has been searched for quasi elastically produced charmed baryons ( L+c,Sc and S*c ). The search has been performed in two exclusive decay channels of the L+c, both including a L . Also, the semi-inclusive decay channels L+c,Sc,S *c→L+X have been studied. Kinematic selection criteria have been chosen in order to obtain samples enriched with quasi elastic charm events. Signal efficiencies and background expectations have been estimated by Monte Carlo simulations. The observed number of events in each searched channel has been found to agree with the background expectation from charged and neutral current reactions and an upper limit for the cross section has been derived. For the quasi elastic charm production cross section averaged over the neutrino energy spectrum (&lan...
One Dimensional Quasi-Exactly Solvable Differential Equations
Fasihi, Mohammad A.
2006-01-01
In this paper by means of similarity transformation we find some one-dimensional quasi-exactly solvable differential equations and their related Hamiltonians which appear in physical problems. We have provided also two examples with application of these differential equations.
A Search Model with a Quasi-Network
DEFF Research Database (Denmark)
Ejarque, Joao Miguel
This paper adds a quasi-network to a search model of the labor market. Fitting the model to an average unemployment rate and to other moments in the data implies the presence of the network is not noticeable in the basic properties of the unemployment and job finding rates. However, the network c...
PT-symmetry in quasi-integrable models
Assis, P E G
2015-01-01
We reinforce the observations of almost stable scattering in nonintegrable models and show that $\\mathcal{PT}$-symmetry can be used as a guiding principle to select relevant systems also when it comes to integrability properties. We show that the presence of unbroken $\\mathcal{PT}$-symmetry in classical field theories produces quasi-integrable excitations with asymptotically conserved charges.
A Search Model with a Quasi-Network
DEFF Research Database (Denmark)
Ejarque, Joao Miguel
This paper adds a quasi-network to a search model of the labor market. Fitting the model to an average unemployment rate and to other moments in the data implies the presence of the network is not noticeable in the basic properties of the unemployment and job finding rates. However, the network...
Failure processes in soft and quasi-brittle materials with nonhomogeneous microstructures
Spring, Daniel W.
Material failure pervades the fields of materials science and engineering; it occurs at various scales and in various contexts. Understanding the mechanisms by which a material fails can lead to advancements in the way we design and build the world around us. For example, in structural engineering, understanding the fracture of concrete and steel can lead to improved structural systems and safer designs; in geological engineering, understanding the fracture of rock can lead to increased efficiency in oil and gas extraction; and in biological engineering, understanding the fracture of bone can lead to improvements in the design of bio-composites and medical implants. In this thesis, we numerically investigate a wide spectrum of failure behavior; in soft and quasi-brittle materials with nonhomogeneous microstructures considering a statistical distribution of material properties. The first topic we investigate considers the influence of interfacial interactions on the macroscopic constitutive response of particle reinforced elastomers. When a particle is embedded into an elastomer, the polymer chains in the elastomer tend to adsorb (or anchor) onto the surface of the particle; creating a region in the vicinity of each particle (often referred to as an interphase) with distinct properties from those in the bulk elastomer. This interphasial region has been known to exist for many decades, but is primarily omitted in computational investigations of such composites. In this thesis, we present an investigation into the influence of interphases on the macroscopic constitutive response of particle filled elastomers undergoing large deformations. In addition, at large deformations, a localized region of failure tends to accumulate around inclusions. To capture this localized region of failure (often referred to as interfacial debonding), we use cohesive zone elements which follow the Park-Paulino-Roesler traction-separation relation. To account for friction, we present a new
Test-particle simulations in increasingly strong turbulence
Pontius, D. H., Jr.; Gray, P. C.; Matthaeus, W. H.
1995-01-01
Quasi-linear theory supposes that the energy in resonant fluctuations is small compared to that in the mean magnetic field. This is evident in the fact that the zeroth-order particle trajectories are helices about a mean field B(sub o) that is spatially uniform over many correlation lengths. However, in the solar wind it is often the case that the fluctuating part of the field is comparable in magnitude to the mean part. It is generally expected that quasi-linear theory remains viable for particles that are in resonance with a region of the fluctuation spectrum having only small energy density, but even so, care must be taken when comparing simulations to theoretical predictions. We have performed a series of test-particle simulations to explore the evolution of ion distributions in turbulent situations with varying levels of magnetic fluctuations. As delta-B/B(sub o) is increased the distinctions among absolute pitch angle (defined relative to B(sub o)), local pitch angle (defined relative to B(x)), and magnetic moment become important, some of them exhibiting periodic sloshing unrelated to the nonadiabatic processes of interest. Comparing and contrasting the various runs illustrates the phenomena that must be considered when the premise underlying quasi-linear theory are relaxed.
Furbish, D. J.
2009-04-01
Sediment particles transported by rainsplash, by bioturbation, and as bedload in turbulent flows, undergo motions that are quasi-random in magnitude and direction. Moreover, these motions characteristically are intermittent, in that particles are mostly at rest most of the time, and heterogeneous, in that the volumetric or areal concentration of particles in motion at any instant is spatially patchy. These particle motions can be formulated as a stochastic processes involving both advective and dispersive parts. By taking into account the intermittent activity of particles, and separating this activity from the physics of motion in the parametric description of transport, the formulation indicates that gradients in particle activity can have a key role in transport. The formulation illustrates, for example, how the growth of soil mounds beneath desert shrubs involves differential rainsplash that initially causes more grains to be splashed inward beneath protective shrub canopies than outward. This ‘harvesting' of nearby soil material, including nutrients, means that shrubs locally participate in regulating the rate sediment transport down a hillslope. With soil bioturbation, spatial variations in the disturbance frequency strongly influence the mixing of soil constituents, including distinct particle fractions (such as specific size or mineral fractions, seeds, or debitage), or elements and compounds adsorbed to particles. The formulation also provides a probabilistic version of the Exner equation. During bedload transport, gradients in particle activity, through both advective and dispersive effects, may contribute importantly to the local divergence of the particle flux, thereby influencing initial bedform growth.
Lubrication approximation for micro-particles moving along parallel walls
Ekiel-Jezewska, M L; Blawzdziewicz, J; Feuillebois, F
2008-01-01
Lubrication expressions for the friction coefficients of a spherical particle moving in a fluid between and along two parallel solid walls are explicitly evaluated in the low-Reynolds-number regime. They are used to determine lubrication expression for the particle free motion under an ambient Poiseuille flow. The range of validity and the accuracy of the lubrication approximation is determined by comparing with the corresponding results of the accurate multipole procedure. The results are applicable for thin, wide and long microchannels, or quasi-two-dimensional systems.
Wave-particle interactions in the outer radiation belts
Agapitov, O V; Artemyev, A V; Mourenas, D; Krasnoselskikh, V V
2015-01-01
Data from the Van Allen Probes have provided the first extensive evidence of non-linear (as opposed to quasi-linear) wave-particle interactions in space with the associated rapid (fraction of a bounce period) electron acceleration to hundreds of keV by Landau resonance in the parallel electric fields of time domain structures (TDS) and very oblique chorus waves. The experimental evidence, simulations, and theories of these processes are discussed. {\\bf Key words:} the radiation belts, wave-particle interaction, plasma waves and instabilities
Study of atomic jumps in quasi-crystals; Etude des sauts atomiques dans les quasi-cristaux
Energy Technology Data Exchange (ETDEWEB)
Lyonnard, S
1997-05-07
The terminology phason used in quasicrystals to refer to atomic jumps. The study of the hopping process is important for the understanding of many basic issues in quasi-crystallography: structure, stability, diffusion, phase transitions between quasicrystals and approximants, mechanical properties. Quasi-elastic neutron scattering allows to find the characteristics of each elementary jump: chemical species involves, relaxation times, activation energies, jump distances and orientations. We performed a series of experiments in the perfect icosahedral phases AlFeCu and AlMnPd, on both powders and single domain samples, using time-of-flight, backscattering and triple axis spectrometers. We evidenced the existence of very fast phason hopping, and studied about ten different atomic jumps. An unusual temperature dependence has been found systematically: each process is assisted by a thermally activated mechanism. The assistance process has to be determined case by case, but the more plausible explanation invokes assistance by phonons or phason clouds. Moreover, the dependence of the quasi elastic signal as a function of the momentum transfer shows that the jumps are local and do not give rise to any long-range diffusion. Phason hopping mainly corresponds to the atom moving forwards and backwards between two energetically equivalent sites. Finally, we have been able to show that the jumps occur along the various quasi-crystalline symmetry axes. (author) 91 refs.
On the Coefficients Problem of Quasi-convex Mappings and Starlike Mapppings in Cn
Institute of Scientific and Technical Information of China (English)
LIUWei-xian; WANGYu-min
2003-01-01
Let Bn be the unit ball in Cn, we study quasi-convex mappings and starlike mappings on Bn.The upper bounds of second order item coefficients ofr quasi-convex mappings and starlike mappings are obtained.
Quasi-sure Limit Theorem of Parabolic Stochastic Partial Differential Equations
Institute of Scientific and Technical Information of China (English)
Xi Cheng ZHANG
2004-01-01
In this paper we prove a quasi-sure limit theorem of parabolic stochastic partial differential equations with smooth coefficients and some initial conditions, by the way, we obtain the quasi-sure continuity of the solution.
Some Hermite–Hadamard Type Inequalities for Geometrically Quasi-Convex Functions
Indian Academy of Sciences (India)
Feng Qi; Bo-Yan Xi
2014-08-01
In the paper, we introduce a new concept ‘geometrically quasi-convex function’ and establish some Hermite–Hadamard type inequalities for functions whose derivatives are of geometric quasi-convexity.
Approximate Integrals of rf-driven Particle Motion in Magnetic Field
Energy Technology Data Exchange (ETDEWEB)
I.Y. Dodin; N.J. Fisch
2004-04-26
For a particle moving in nonuniform magnetic field under the action of an rf wave, ponderomotive effects result from rf-driven oscillations nonlinearly coupled with Larmor rotation. Using Lagrangian and Hamiltonian formalism, we show how, despite this coupling, two independent integrals of the particle motion are approximately conserved. Those are the magnetic moment of free Larmor rotation and the quasi-energy of the guiding center motion parallel to the magnetic field. Under the assumption of non-resonant interaction of the particle with the rf field, these integrals represent adiabatic invariants of the particle motion.
Thermodynamic properties of a quasi-harmonic model for ferroelectric transitions
Energy Technology Data Exchange (ETDEWEB)
Mkam Tchouobiap, S E [Laboratory of Research on Advanced Materials and Nonlinear Sciences (LaRAMaNS), Department of Physics, Faculty of Science, University of Buea, PO Box 63, Buea (Cameroon); Mashiyama, H, E-mail: esmkam@yahoo.com [Department of Physics, Faculty of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512 (Japan)
2011-03-30
Within a framework of a quasi-harmonic model for quantum particles in a local potential of the double Morse type and within the mean-field approximation for interactions between particles, we investigate the thermodynamic properties of ferroelectric materials. A quantum thermodynamic treatment gives analytic expressions for the internal energy, the entropy, the specific heat, and the static susceptibility. The calculated thermodynamic characteristics are studied as a function of temperature and energy barrier, where it is shown that at the proper choice of the theory parameters, particularly the energy barrier, the model system exhibits characteristic features of either second-order tricritical or first-order phase transitions. Our results indicate that the barrier energy seems to be an important criterion for the character of the structural phase transition. The influence of quantum fluctuations manifested on zero-point energy on the phase transition and thermodynamic properties is analyzed and discussed. This leads to several quantum effects, including the existence of a saturation regime at low temperatures, where the order parameter saturates giving thermodynamic saturation of the calculated thermodynamic quantities. It is found that both quantum effects and energy barrier magnitude have an important influence on the thermodynamic properties of the ferroelectric materials and on driving the phase transition at low temperatures. Also, the analytical parameters' effect on the transition temperature is discussed, which seems to give a general insight into the structural phase transition and its nature.
Fouvry, Jean-Baptiste; Magorrian, John
2016-01-01
We derive the kinetic equation that describes the secular evolution of a large set of particles orbiting a dominant massive object, such as stars bound to a supermassive black hole or a proto-planetary debris disc encircling a star. Because the particles move in a quasi-Keplerian potential, their orbits can be approximated by ellipses whose orientations remain fixed over many dynamical times. The kinetic equation is obtained by simply averaging the BBGKY equations over the fast angle that describes motion along these ellipses. This so-called Balescu-Lenard equation describes self-consistently the long-term evolution of the distribution of quasi-Keplerian orbits around the central object: it models the diffusion and drift of their actions, induced through their mutual resonant interaction. Hence, it is the master equation that describes the secular effects of resonant relaxation. We show how it captures the phenonema of mass segregation and of the relativistic Schwarzschild barrier recently discovered in $N$-b...
Fouvry, J.-B.; Pichon, C.; Magorrian, J.
2017-02-01
We derive the kinetic equation that describes the secular evolution of a large set of particles orbiting a dominant massive object, such as stars bound to a supermassive black hole or a proto-planetary debris disc encircling a star. Because the particles move in a quasi-Keplerian potential, their orbits can be approximated by ellipses whose orientations remain fixed over many dynamical times. The kinetic equation is obtained by simply averaging the BBGKY equations over the fast angle that describes motion along these ellipses. This so-called Balescu-Lenard equation describes self-consistently the long-term evolution of the distribution of quasi-Keplerian orbits around the central object: it models the diffusion and drift of their actions, induced through their mutual resonant interaction. Hence, it is the master equation that describes the secular effects of resonant relaxation. We show how it captures the phenonema of mass segregation and of the relativistic Schwarzschild barrier recently discovered in N-body simulations.
Particle Scattering off of Right-Handed Dispersive Waves
Schreiner, Cedric; Spanier, Felix
2016-01-01
Resonant scattering of fast particles off low frequency plasma waves is a major process determining transport characteristics of energetic particles in the heliosphere and contributing to their acceleration. Usually, only Alfv\\'en waves are considered for this process, although dispersive waves are also present throughout the heliosphere. We investigate resonant interaction of energetic electrons with dispersive, right-handed waves. For the interaction of particles and a single wave a variable transformation into the rest frame of the wave can be performed. Here, wellestablished analytic models derived in the framework of magnetostatic quasi-linear theory (QLT) can be used as a reference to validate simulation results. However, this approach fails as soon as several dispersive waves are involved. Based on analytic solutions modeling the scattering amplitude in the magnetostatic limit, we present an approach to modify these equations for the use in the plasma frame. Thereby we aim at a description of particle ...
Dry deposition of large, airborne particles onto a surrogate surface
Kim, Eugene; Kalman, David; Larson, Timothy
Simultaneous measurements of particle dry deposition flux and airborne number concentration in the open atmosphere were made using three different types of artificially generated particles in the size range 10-100 μm - perlite, diatomaceous earth and glass beads. A combination of gravimetric analysis, automated microscopy and sonic anemometry provided size-resolved estimates of both the inertial and gravitational components of the quasi-laminar layer particle deposition velocity, ( Vd) b, as a function of size. Eddy inertial deposition efficiency ( ηdI) was determined as a function of dimensionless eddy Stokes number (Stk e). In the range 3PNL-SA-6721, Pacific Northwest Laboratories, Richland, WA), used in several regulatory models, significantly under-predicted (up to seven times) ( Vd) b for large particles ( da>10 μm).
The global convergence of the non-quasi-Newton methods with non-monotone line search
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The non-quasi-Newton methods for unconstrained optimization was investigated. Non-monotone line search procedure is introduced, which is combined with the non-quasi-Newton family. Under the uniform convexity assumption on objective function, the global convergence of the non-quasi-Newton family was proved.Numerical experiments showed that the non-monotone line search was more effective.
Search for Quasi-isodynamic Effects in TJ-II; Busqueda de efectos quasi-isodinamicos en el TJ-II
Energy Technology Data Exchange (ETDEWEB)
Guasp, J.; Liniers, M. [Ciemat. Madrid (Spain)
2000-07-01
The possibility of quasi-isodynamics effects (QID) in the TJ-II helical axis Stellarator has been explored maintaining the present setting for the toroidal field coils (TFC). In order to do this it has been necessary to implement a new method of calculation, using real space coordinates to follow the particle trajectories, instated the Boozer coordinates as was usual formerly. The result for the exploration of the flexibility diagram of TJ-II, including magnetic axis a shift effects, has been negative. It seems that there are not useful QID regions in TJ-II with the present setting of TFC carrying equal currents in all coils. Nevertheless, in spite of this negative result, the calculation in real space and, mainly, the grater number of configurations analysed, have produced a series of new important results, some of them unexpected. The influence of rational surfaces is very important. Optima and minima of confinement alternate at both sides of the rational values (mainly for the 1/2 by period) in a way very similar to the radial electric field resonance cases. This effect originates in the peculiar orbit topology in the presence of diffusion. Some lines of study are proposed to deal with this problem. Finally, the negative result of the QID search suggests the convenience to start a similar search without the restriction of equal currents on all the TEC. (Author) 18 refs.
Phase equilibria in stratified thin liquid films stabilized by colloidal particles
Blawzdziewicz, J.; Wajnryb, E.
2005-01-01
Phase equilibria between regions of different thickness in thin liquid films stabilized by colloidal particles are investigated using a quasi-two-dimensional thermodynamic formalism. Appropriate equilibrium conditions for the film tension, normal pressure, and chemical potential of the particles in the film are formulated, and it is shown that the relaxation of these parameters occurs consecutively on three distinct time scales. Film stratification is described quantitatively for a hard-spher...
Two-particle interference of electron pairs on a molecular level
Waitz, M; Lower, J; Schober, C; Keiling, M; Pitzer, M; Mertens, K; Martins, M; Viefhaus, J; Klumpp, S; Weber, T; Schmidt-Böcking, H; Schmidt, L Ph H; Morales, F; Miyabe, S; Rescigno, T N; McCurdy, C W; Martin, F; Williams, J B; Schöffler, M S; Jahnke, T; Dörner, R
2016-01-01
We investigate the photo-doubleionization of $H_2$ molecules with 400 eV photons. We find that the emitted electrons do not show any sign of two-center interference fringes in their angular emission distributions if considered separately. In contrast, the quasi-particle consisting of both electrons (i.e. the "dielectron") does. The work highlights the fact that non-local effects are embedded everywhere in nature where many-particle processes are involved.
Energy loss of a heavy particle near 3D charged rotating hairy black hole
Energy Technology Data Exchange (ETDEWEB)
Naji, Jalil [Ilam University, Physics Department, P.O.Box 69315-516, Ilam (Iran, Islamic Republic of)
2014-01-15
In this paper we consider a charged rotating black hole in three dimensions with a scalar charge and discuss the energy loss of a heavy particle moving near the black-hole horizon. We also study quasi-normal modes and find the dispersion relations. We find that the effect of scalar charge and electric charge increases the energy loss. (orig.)
Energy loss of a heavy particle near 3D charged rotating hairy black hole
Naji, Jalil
2014-01-01
In this paper we consider a charged rotating black hole in three dimensions with a scalar charge and discuss the energy loss of a heavy particle moving near the black-hole horizon. We also study quasi-normal modes and find the dispersion relations. We find that the effect of scalar charge and electric charge increases the energy loss.
Bergshoeff, Eric; Gomis, Joaquim; Longhi, Giorgio
2014-01-01
We investigate particles whose dynamics are invariant under the Carroll group. Although a single, free such Carroll particle has no non-trivial dynamics (the Carroll particle does not move), we show that non-trivial dynamics exists for a set of interacting Carroll particles. Furthermore, we gauge th