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Search Results: 1 - 10 of 299 matches for " Hidehiko Kita "
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On Test Data Compression Using Selective Don’t-Care Identification
On Test Data Compression Using Selective Don t-Care Identification

Terumine Hayashi,Haruna Yoshioka,Tsuyoshi Shinogi,Hidehiko Kita,Haruhiko Takase,
TerumineHayashi
,HarunaYoshioka,TsuyoshiShinogi,HidehikoKita,HaruhikoTakase

计算机科学技术学报 , 2005,
Abstract: This paper proposes an effective method for reducing test data volume under multiple scan chain designs. The proposed method is based on reduction of distinct scan vectors using selective dont-care identification. Selective dont-care identification is repeatedly executed under condition that each bit of frequent scan vectors is fixed to binary values (0 or 1). Besides, a code extension technique is adopted for improving compression efficiency with keeping decompressor circuits simple in the manner that the code length for infrequent scan vectors is designed as double of that for frequent ones. The effectiveness of the proposed method is shown through experiments for ISCAS89 and ITC99 benchmark circuits.
Endoscopic Submucosal Dissection for Early Gastric Cancer  [PDF]
Kouichi Nonaka, Hiroto Kita
Journal of Cancer Therapy (JCT) , 2013, DOI: 10.4236/jct.2013.41A004
Abstract: The field of endoscopy has progressed markedly and become widespread in recent years, and the role of minimally invasive endoscopic treatment has become increasingly more important with the increase in the number of patients in whom gastric cancer is detected at an early stage. In addition, the characteristics of early gastric cancer, which can be curably treated by mucosal resection alone just as by surgical cancer resection, were clarified, and endoscopic submucosal dissection (ESD) was developed as a highly curable, minimally invasive treatment, that is gaining popularity. In this paper, we describe the technical details and complications of ESD for early gastric cancer, including their management.
A unified approach to marginal equivalence in the general framework of group invariance
Hidehiko Kamiya
Statistics , 2014,
Abstract: Two Bayesian models with different sampling densities are said to be marginally equivalent if the joint distribution of observables and the parameter of interest is the same for both models. We discuss marginal equivalence in the general framework of group invariance. We introduce a class of sampling models and establish marginal equivalence when the prior for the nuisance parameter is relatively invariant. We also obtain some robustness properties of invariant statistics under our sampling models. Besides the prototypical example of $v$-spherical distributions, we apply our general results to two examples---analysis of affine shapes and principal component analysis.
Self-consistent perturbation expansion for Bose-Einstein condensates satisfying Goldstone's theorem and conservation laws
Takafumi Kita
Physics , 2009, DOI: 10.1103/PhysRevB.80.214502
Abstract: Quantum-field-theoretic descriptions of interacting condensed bosons have suffered from the lack of self-consistent approximation schemes satisfying Goldstone's theorem and dynamical conservation laws simultaneously. We present a procedure to construct such approximations systematically by using either an exact relation for the interaction energy or the Hugenholtz-Pines relation to express the thermodynamic potential in a Luttinger-Ward form. Inspection of the self-consistent perturbation expansion up to the third order with respect to the interaction shows that the two relations yield a unique identical result at each order, reproducing the conserving-gapless mean-field theory [T. Kita, J. Phys. Soc. Jpn. 74, 1891 (2005)] as the lowest-order approximation. The uniqueness implies that the series becomes exact when infinite terms are retained. We also derive useful expressions for the entropy and superfluid density in terms of Green's function and a set of real-time dynamical equations to describe thermalization of the condensate.
Entropy in Nonequilibrium Statistical Mechanics
Takafumi Kita
Physics , 2006, DOI: 10.1143/JPSJ.76.067001
Abstract: Entropy in nonequilibrium statistical mechanics is investigated theoretically so as to extend the well-established equilibrium framework to open nonequilibrium systems. We first derive a microscopic expression of nonequilibrium entropy for an assembly of identical bosons/fermions interacting via a two-body potential. This is performed by starting from the Dyson equation on the Keldysh contour and following closely the procedure of Ivanov, Knoll and Voskresensky [Nucl. Phys. A {\bf 672} (2000) 313]. The obtained expression is identical in form with an exact expression of equilibrium entropy and obeys an equation of motion which satisfies the $H$-theorem in a limiting case. Thus, entropy can be defined unambiguously in nonequilibrium systems so as to embrace equilibrium statistical mechanics. This expression, however, differs from the one obtained by Ivanov {\em et al}., and we show explicitly that their ``memory corrections'' are not necessary. Based on our expression of nonequilibrium entropy, we then propose the following principle of maximum entropy for nonequilibrium steady states: ``The state which is realized most probably among possible steady states without time evolution is the one that makes entropy maximum as a function of mechanical variables, such as the total particle number, energy, momentum, energy flux, etc.'' During the course of the study, we also develop a compact real-time perturbation expansion in terms of the matrix Keldysh Green's function.
Principle of Maximum Entropy Applied to Rayleigh-Bénard Convection
Takafumi Kita
Physics , 2006, DOI: 10.1143/JPSJ.75.124005
Abstract: A statistical-mechanical investigation is performed on Rayleigh-B\'enard convection of a dilute classical gas starting from the Boltzmann equation. We first present a microscopic derivation of basic hydrodynamic equations and an expression of entropy appropriate for the convection. This includes an alternative justification for the Oberbeck-Boussinesq approximation. We then calculate entropy change through the convective transition choosing mechanical quantities as independent variables. Above the critical Rayleigh number, the system is found to evolve from the heat-conducting uniform state towards the convective roll state with monotonic increase of entropy on the average. Thus, the principle of maximum entropy proposed for nonequilibrium steady states in a preceding paper is indeed obeyed in this prototype example. The principle also provides a natural explanation for the enhancement of the Nusselt number in convection.
Entropy Change through Rayleigh-Bénard Convective Transition with Rigid Boundaries
Takafumi Kita
Physics , 2007, DOI: 10.1143/JPSJ.76.064006
Abstract: The previous investigation on Rayleigh-B\'enard convection of a dilute classical gas [T. Kita: J. Phys. Soc. Jpn. {\bf 75} (2006) 124005] is extended to calculate entropy change of the convective transition with the rigid boundaries. We obtain results qualitatively similar to those of the stress-free boundaries. Above the critical Rayleigh number, the roll convection is realized among possible steady states with periodic structures, carrying the highest entropy as a function of macroscopic mechanical variables.
Introduction to Nonequilibrium Statistical Mechanics with Quantum Field
Takafumi Kita
Physics , 2010, DOI: 10.1143/PTP.123.581
Abstract: In this article, we present a concise and self-contained introduction to nonequilibrium statistical mechanics with quantum field theory by considering an ensemble of interacting identical bosons or fermions as an example. Readers are assumed to be familiar with the Matsubara formalism of equilibrium statistical mechanics such as Feynman diagrams, the proper self-energy, and Dyson's equation. The aims are threefold: (i) to explain the fundamentals of nonequilibrium quantum field theory as simple as possible on the basis of the knowledge of the equilibrium counterpart; (ii) to elucidate the hierarchy in describing nonequilibrium systems from Dyson's equation on the Keldysh contour to the Navier-Stokes equation in fluid mechanics via quantum transport equations and the Boltzmann equation; (iii) to derive an expression of nonequilibrium entropy that evolves with time. In stage (i), we introduce nonequilibrium Green's function and the self-energy uniquely on the round-trip Keldysh contour, thereby avoiding possible confusions that may arise from defining multiple Green's functions at the very beginning. We try to present the Feynman rules for the perturbation expansion as simple as possible. In particular, we focus on the self-consistent perturbation expansion with the Luttinger-Ward thermodynamic functional, i.e., Baym's Phi-derivable approximation, which has a crucial property for nonequilibrium systems of obeying various conservation laws automatically. We also show how the two-particle correlations can be calculated within the Phi-derivable approximation, i.e., an issue of how to handle the "Bogoliubov-Born-Green-Kirkwood-Yvons (BBGKY) hierarchy".
Hall Coefficient of Equilibrium Supercurrents Flowing inside Superconductors
Takafumi Kita
Physics , 2009, DOI: 10.1103/PhysRevB.79.024521
Abstract: We study augmented quasiclassical equations of superconductivity with the Lorentz force, which is missing from the standard Ginzburg-Landau and Eilenberger equations. It is shown that the magnetic Lorentz force on equilibrium supercurrents induces finite charge distribution and the resulting electric field to balance the Lorentz force. An analytic expression is obtained for the corresponding Hall coefficient of clean type-II superconductors with simultaneously incorporating the Fermi-surface and gap anisotropies. It has the same sign and magnitude at zero temperature as the normal state for an arbitrary pairing, having no temperature dependence specifically for the s-wave pairing. The gap anisotropy may bring a considerable temperature dependence in the Hall coefficient and can lead to its sign change as a function of temperature, as exemplified for a model d-wave pairing with a two-dimensional Fermi surface. The sign change may be observed in some high-$T_{c}$ superconductors.
On the density matrix of nonequilibrium steady-state statistical mechanics
Takafumi Kita
Physics , 2002, DOI: 10.1143/JPSJ.71.1795
Abstract: This paper derives a density matrix of the steady-state statistical mechanics compatible with the steady-state thermodynamics proposed by Oono and Paniconi [Prog. Theor. Phys. Suppl. {\bf 130}, 29 (1998)]. To this end, we adopt three plausible basic assumptions for uniform steady states: (i) equivalence between any two subsystems of the total, (ii) statistical independence between any two subsystems, and (iii) additivity of energy. With a suitable definition of energy, it is then shown that uniform steady states driven by mechanical forces may be described by the Gibbs distribution.
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