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Search Results: 1 - 10 of 380259 matches for " T. J.;YOSHIDA "
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ACTA MATHEMATICA UNIVERSITATIS COMENIANAE
J. JAROS, T. KUSANO and N. YOSHIDA
ACTA MATHEMATICA UNIVERSITATIS COMENIANAE , 2000,
Abstract: . In the paper a nonlinear version of an identity known in the literature as the Picone's formula is derived and then it is used to extend the classical Sturmian comparison theory to forced superlinear equations of the second order.
Stability of Neutral Fermi Balls with Multi-Flavor Fermions
T. Yoshida,K. Ogure,J. Arafune
Physics , 2003, DOI: 10.1103/PhysRevD.68.023519
Abstract: A Fermi ball is a kind of non-topological soliton, which is thought to arise from the spontaneous breaking of an approximate $Z_2$ symmetry and to contribute to cold dark matter. We consider a simple model in which fermion fields with multi-flavors are coupled to a scalar field through Yukawa coupling, and examine how the number of the fermion flavors affects the stability of the Fermi ball against the fragmentation. (1)We find that the Fermi ball is stable against the fragmentation in most cases even in the lowest order thin-wall approximation. (2)We then find that in the other specific cases, the stability is marginal in the lowest order thin-wall approximation, and the next-to-leading order correction determines the stable region of the coupling constants; We examine the simplest case where the total fermion number $N_i$ and the Yukawa coupling constant $G_i$ of each flavor $i$ are common to the flavor, and find that the Fermi ball is stable in the limited region of the parameters and has the broader region for the larger number of the flavors.
Stable Neutral Fermi Ball
K. Ogure,T. Yoshida,J. Arafune
Physics , 2002, DOI: 10.1103/PhysRevD.67.123518
Abstract: Fermi Ball is a kind of nontopological soliton with fermions trapped in its domain wall, and is suggested to arises from the spontaneous symmetry breaking of the approximate $Z_2$ symmetry in the early universe. We find that the neutral thin-wall Fermi Ball is stable in the limited region of the scalar self-coupling constant $\lambda$ and the Yukawa coupling constant $G$. We find that the Fermi Ball is stabilized due to the curvature effect of the domain wall caused by the fermion sector. We also discuss whether such stable Fermi Balls may contribute to the cold dark matter.
Stability of Fermi ball against deformation from spherical shape
T. Yoshida,K. Ogure,J. Arafune
Physics , 2002, DOI: 10.1103/PhysRevD.67.083506
Abstract: The stability of a Fermi ball (F-ball), which is a kind of non-topological soliton accompanying the breakdown of the approximate $Z_2$ symmetry, is investigated in three situations: the case it is electrically neutral, the case it is electrically charged and unscreened, and the case it is electrically charged and screened. We argue only the third case is physically meaningful since the neutral F-ball is unstable and the case of the unscreened charged one is observationally excluded when it has a sizable contribution to CDM. We found that the energy scale of the breakdown of the approximate $Z_2$ symmetry $v$ should satisfy $v<3\times 10^6 {GeV}$ if the F-ball is a main component of CDM.
MODEL OF A PROCESS FOR DRYING Eucalyptus spp AT HIGH TEMPERATURES
PINHEIRO, P. C. C.;RAAD, T. J.;YOSHIDA, M. I.;
Brazilian Journal of Chemical Engineering , 1998, DOI: 10.1590/S0104-66321998000400007
Abstract: a mathematical model of a process for drying of eucalyptus spp is presented. this model was based on fundamental heat and mass transfer equations and it was numerically solved using a segregated finite volume method. software in the fortran language was developed to solve the mathematical model. the kinetic parameters of drying for eucalyptus spp were experimentally obtained by isothermal thermogravimetry (tg). the theoretical results generated using the mathematical model were validated by experimental data.
Spatial distribution of dust's optical properties over the Sahara and Asia inferred from Moderate Resolution Imaging Spectroradiometer
M. Yoshida,J. M. Haywood,B. T. Johnson,H. Murakami
Atmospheric Chemistry and Physics Discussions , 2012, DOI: 10.5194/acpd-12-31107-2012
Abstract: There is a great deal of uncertainty surrounding the role of mineral dust aerosols in the earth's climate system. One reason for this uncertainty is that the optical properties of mineral dust, such as its single scattering albedo (the ratio of scattering to total extinction), are poorly understood because ground observations are limited to several locations and the satellite standard products are not available due to the excessively bright surface of the desert in the visible wavelength. We develop a method in this paper to estimate the spatial distributions of the aerosol single scattering albedo (ω0) and optical depth (τa), with daily 1 degree latitude and 1 degree longitude resolution, using data from Moderate Resolution Imaging Spectroradiometer (MODIS), as well as model simulations of radiative transfer. This approach is based on the "critical surface reflectance" method developed in the literature, which estimates ω0 from the top of the atmospheric radiance. We confirm that the uncertainties in our estimation of ω0 and τa are suitably minor and that the characteristic spatial distributions estimated over the Sahara and Asia are significant. The results for the Sahara indicate good correlation between ω0 and the surface reflectance and between ω0 and τa. Therefore, ω0 is determined mainly by the mineral composition of surface dust and/or the optical depth of airborne dust in the Sahara. On the other hand, the relationships between ω0, τa, and the surface reflectance are less clear in Asia than in the Sahara, and the values of ω0 are smaller than those in the Sahara. The regions with small ω0 values are consistent with the regions where coal-burning smoke and carbonaceous aerosols are thought to be transported, as reported in previous studies. Because the coal-burning and carbonaceous aerosols are known to be more absorptive and have smaller ω0 values than dust aerosols, our results indicate that the dust aerosols in Asia are contaminated by these anthropogenic aerosols. The spatial distribution of dust optical properties obtained in our work could be useful in understanding the roles of dust aerosols in the earth's climate system, most likely through future collaboration with regional and global modelling studies.
MODEL OF A PROCESS FOR DRYING Eucalyptus spp AT HIGH TEMPERATURES
PINHEIRO P. C. C.,RAAD T. J.,YOSHIDA M. I.
Brazilian Journal of Chemical Engineering , 1998,
Abstract: A mathematical model of a process for drying of Eucalyptus spp is presented. This model was based on fundamental heat and mass transfer equations and it was numerically solved using a segregated finite volume method. Software in the FORTRAN language was developed to solve the mathematical model. The kinetic parameters of drying for Eucalyptus spp were experimentally obtained by isothermal thermogravimetry (TG). The theoretical results generated using the mathematical model were validated by experimental data.
The Most Likely Sources of High Energy Cosmic-Ray Electrons in Supernova Remnants
T. Kobayashi,Y. Komori,K. Yoshida,J. Nishimura
Physics , 2003, DOI: 10.1086/380431
Abstract: Evidences of non-thermal X-ray emission and TeV gamma-rays from the supernova remnants (SNRs) has strengthened the hypothesis that primary Galactic cosmic-ray electrons are accelerated in SNRs. High energy electrons lose energy via synchrotron and inverse Compton processes during propagation in the Galaxy. Due to these radiative losses, TeV electrons liberated from SNRs at distances larger than ~1 kpc, or times older than ~10^5 yr, cannot reach the solar system. We investigated the cosmic-ray electron spectrum observed in the solar system using an analytical method, and considered several candidate sources among nearby SNRs which may contribute to the high energy electron flux. Especially, we discuss the effects for the release time from SNRs after the explosion, as well as the deviation of a source spectrum from a simple power-law. From this calculation, we found that some nearby sources such as the Vela, Cygnus Loop, or Monogem could leave unique signatures in the form of identifiable structure in the energy spectrum of TeV electrons and show anisotropies towards the sources, depending on when the electrons are liberated from the remnant. This suggests that, in addition to providing information on the mechanisms of acceleration and propagation of cosmic-rays, specific cosmic-ray sources can be identified through the precise electron observation in the TeV region.
Parity-sensitive measurements based on ferromagnet/superconductor tunneling junctions
T. Hirai,N. Yoshida,Y. Tanaka,J. Inoue,S. Kashiwaya
Physics , 2001, DOI: 10.1143/JPSJ.70.1885
Abstract: A method to identify the parity of unconventional superconductors is proposed based on tunneling spectroscopy. For a model of calculation, we adopt a ferromagnet/superconductor (F/S) junction of which tunneling current is spin polarized. The tunneling conductance spectra are shown to be quite sensitive to the direction of the magnetization axis in the ferromagnet only when the superconductor has odd parity. Therefore, it is possible to distinguish the parity of the superconductor by measuring the tunneling spectroscopy in F/S junctions.
Interface effects on the shot noise in normal metal- d-wave superconductor Junctions
Y. Tanaka,T. Asai,N. Yoshida,J. Inoue,S. Kashiwaya
Physics , 1999, DOI: 10.1103/PhysRevB.61.R11902
Abstract: The current fluctuation in normal metal / d-wave superconductor junctions are studied for various orientation of the crystal by taking account of the spatial variation of the pair potentials. Not only the zero-energy Andreev bound states (ZES) but also the non-zero energy Andreev bound states influence on the properties of differential shot noise. At the tunneling limit, the noise power to current ratio at zero voltage becomes 0, once the ZES are formed at the interface. Under the presence of a subdominant s-wave component at the interface which breaks time-reversal symmetry, the ratio becomes 4e
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