From Networks to Time Series
Yutaka Shimada; Tohru Ikeguchi; Takaomi Shigehara
Physical Review Letters, 巻：109, 開始ページ：158701, 2012年, ［査読有り］
Algorithm for Solving Jordan Problem of Block Schur Form
Takuya Matsumoto; Kenji Kudo; Yutaka Kuwajima; Takaomi Shigehara
JSIAM Letters, 巻：4, 開始ページ：9, 終了ページ：12, 2012年, ［査読有り］
実対称固有値問題に対する多分割の分割統治法の分散並列アルゴリズムの提案
田村純一; 坪谷怜; 桑島豊; 重原孝臣
情報処理学会論文誌 コンピューティングシステム(ACS), 巻：3, 号：2, 開始ページ：20, 終了ページ：29, 2010年, ［査読有り］
Algorithm for Computing Jordan Basis
Kenji Kudo; Yoshiaki Kakinuma; Kazuyuki Hiraoka; Hiroki Hashiguchi; Yutaka Kuwajima; Takaomi Shigehara
JSIAM Letters, 巻：2, 開始ページ：119, 終了ページ：122, 2010年, ［査読有り］
Proposal and Efficient Implementation of Multiple Division Divide-and-Conquer Algorithm for SVD
Yutaka Kuwajima; Youichiro Shimizu; Takaomi Shigehara
JSIAM Letters, 巻：2, 開始ページ：91, 終了ページ：94, 2010年, ［査読有り］
Algorithm for Computing Kronecker Basis
Yoshiaki Kakinuma; Kazuyuki Hiraoka; Hiroki Hashiguchi; Yutaka Kuwajima; Takaomi Shigehara
JSIAM Letters, 巻：1, 開始ページ：60, 終了ページ：63, 2009年, ［査読有り］
実対称三重対角固有値問題に対する多分割の分割統治法の改良
桑島豊; 重原孝臣
日本応用数理学会論文誌, 巻：16, 号：4, 開始ページ：453, 終了ページ：480, 2006年, ［査読有り］
実対称三重対角固有値問題の分割統治法の拡張
桑島豊; 重原孝臣
日本応用数理学会論文誌, 巻：15, 号：2, 開始ページ：89, 終了ページ：115, 2005年, ［査読有り］
Continuous Spectra of Generalized Kronig-Penney Model Taksu Cheon; T. Shigehara
Journal of the Physical Society of Japan,
巻：73,
号：11,
開始ページ：2986,
終了ページ：2990, 2004年08月,
［査読有り］The standard Kronig-Penney model with periodic $\delta$ potentials is extended to the cases with generalized contact interactions. The eigen equation which determines the dispersion relation for one-dimensional periodic array of the generalized contact interactions is deduced with the transfer matrix formalism. Numerical results are presented which reveal unexpected band spectra with broader band gap in higher energy region for generic model with generalized contact interaction.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JPSJ.73.2986DOI ID：10.1143/JPSJ.73.2986,
ISSN：0031-9015,
CiNii Articles ID：150000083835 共有メモリ型並列計算機上の行列計算に対する並列化手法の性能評価
舘野諭司; 重原孝臣; 長谷川秀彦; 桧山澄子
情報処理学会論文誌：コンピューティングシステム, 巻：44, 号：SIG 11(ACS 3), 開始ページ：286, 終了ページ：296, 2003年, ［査読有り］
共有メモリ型並列計算機におけるLAPACKの性能評価
西村成司; 舘野諭司; 重原孝臣; 長谷川秀彦; 桧山澄子
情報処理学会論文誌：ハイパフォーマンスコンピューティングシステム, 巻：43, 号：SIG 6 (HPS 5), 開始ページ：163, 終了ページ：171, 2002年, ［査読有り］
Estimation of Camera Rotation Using Quasi Moment Features
H Shimai; T Kawamoto; T Shigehara; T Mishima; M Tanaka; T Kurita
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 巻：E83A, 号：6, 開始ページ：1005, 終了ページ：1013, 2000年06月, ［査読有り］
We present two estimation methods for camera rotation from two images obtained by the active camera before and after rotation. Based on the representation of the projected rotation group, quasi moment features are constructed. Camera rotation can be estimated by applying the singular value decomposition (SVD) or Newton's method to tensor quasi moment features. In both cases, we can estimate 3D rotation of the active camera from only two projected images. We also give some experiments for the estimation of the actual active camera rotation to show the effectiveness of these methods.
IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, 英語, 研究論文（学術雑誌）
ISSN：0916-8508, eISSN：1745-1337, Web of Science ID：WOS:000087901300011
Equivalence of Local and Separable Realizations of the Discontinuity-Inducing Contact Interaction and Its Perturbative RenormalizabilityTaksu Cheon; T. Shigehara; K. Takayanagi
Journal of the Physical Society of Japan,
巻：69,
号：2,
開始ページ：345,
終了ページ：350, 2000年01月,
［査読有り］We prove that the separable and local approximations of the discontinuity-inducing zero-range interaction in one-dimensional quantum mechanics are equivalent. We further show that the interaction allows the perturbative treatment through the coupling renormalization.
Keywords: one-dimensional system, generalized contact interaction, renormalization, perturbative expansion. PACS Nos: 3.65.-w, 11.10.Gh, 31.15.Md
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1143/JPSJ.69.345DOI ID：10.1143/JPSJ.69.345,
ISSN：0031-9015 Realization of a Four Parameter Family of Generalized One-Dimensional Contact Interactions by Three Nearby Delta Potentials with Renormalized Strengths
T Shigehara; H Mizoguchi; T Mishima; T Cheon
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 巻：E82A, 号：9, 開始ページ：1708, 終了ページ：1713, 1999年09月, ［査読有り］
We propose a new method to construct a four parameter family of quantum-mechanical point interactions in one dimension, which is known as all possible self-adjoint extensions of the symmetric operator T = Delta inverted right perpendicularC(0)(infinity)(R\{0}). It is achieved in the small distance limit of equally spaced three neighboring Dirac's delta potentials. The strength for each delta is appropriately renormalized according to the distance and it diverges, in general, in the small distance limit. The validity of our method is ensured by numerical calculations. In general cases except for usual delta, the wave function discontinuity appears around the interaction and one can observe such a tendency even at a finite distance level.
IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG, 英語, 研究論文（学術雑誌）
ISSN：0916-8508, eISSN：1745-1337, Web of Science ID：WOS:000082875700005
Fermion-Boson Duality of One-Dimensional Quantum Particles with Generalized Contact Interaction Taksu Cheon; T. Shigehara
Physical Review Letters,
巻：82,
号：12,
開始ページ：2536,
終了ページ：2539, 1999年06月,
［査読有り］For a system of spinless one-dimensional fermions, the non-vanishing short-range limit of two-body interaction is shown to induce the wave-function discontinuity. We prove the equivalence of this fermionic system and the bosonic particle system with two-body $\delta$-function interaction with the reversed role of strong and weak couplings.
KEYWORDS: one-dimensional system, $\epsilon$-interaction, solvable many-body problem, exact bosonization
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevLett.82.2536DOI ID：10.1103/PhysRevLett.82.2536,
ISSN：0031-9007,
CiNii Articles ID：80011006237 Realizing Discontinuous Wave Functions with Renormalized Short-Range Potentials T Cheon; T Shigehara
Physics Letters A,
巻：243,
号：3,
開始ページ：111,
終了ページ：116, 1998年06月,
［査読有り］We show that the most general three-parameter family of point interactions on the line can be expressed as the self-adjoint local operators in terms of three Dirac's delta functions with the renormalized strengths in the disappearing distances. Experimental realization of the Neumann boundary is discussed. (C) 1998 Elsevier Science B.V.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0375-9601(98)00188-1DOI ID：10.1016/S0375-9601(98)00188-1,
ISSN：0375-9601,
CiNii Articles ID：80010324434,
Web of Science ID：WOS:000074019600001 Chaos Induced by Quantization
Takaomi Shigehara; Hiroshi Mizoguchi; Taketoshi Mishima; Taksu Cheon
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 巻：E81-A, 開始ページ：1762, 終了ページ：1768, 1998年02月, ［査読有り］
In this paper, we show that two-dimensional billiards with point interactions inside exhibit a chaotic nature in the microscopic world, although their classical counterpart is non-chaotic. After deriving the transition matrix of the system by using the self-adjoint extension theory of functional analysis, we deduce the general condition for the appearance of chaos. The prediction is confirmed by numerically examining the statistical properties of energy
spectrum of rectangular billiards with multiple point interactions inside. The dependence of the level statistics on the strength as well a...
英語, 研究論文（学術雑誌）
Spectral Properties of Three-Dimensional Quantum Billiards with a Pointlike Scatterer T. Shigehara; T. Cheon
Physical Review E,
巻：55,
号：6,
開始ページ：6832,
終了ページ：6844, 1997年06月,
［査読有り］We examine the spectral properties of three-dimensional quantum billiards with a single pointlike scatterer inside. It is found that the spectrum shows chaotic (random-matrix-like) characteristics when the inverse of the formal strength <(upsilon)over bar>(-1) is within a band whose width increases parabolically as a function of the energy. This implies that thr spectrum becomes random-matrix-like at very high energy irrespective to the value of the formal strength. The predictions are confirmed by numerical experiments with a rectangular box, The findings for a pointlike scatterer an applied to the case for a small but finite-size impurity. We clarify the proper procedure for its zero-size limit which involves nontrivial divergence. The previously known results in one- and two-dimensional quantum billiards with small impurities inside are also reviewed ed from the present perspective.
AMERICAN PHYSICAL SOC, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevE.55.6832DOI ID：10.1103/PhysRevE.55.6832,
ISSN：1063-651X,
CiNii Articles ID：80009730829,
Web of Science ID：WOS:A1997XG96500071 Resonance Tunneling in Double-Well Billiards with a Pointlike Scatterer Taksu Cheon; T. Shigehara
Physics Letters A,
巻：228,
号：3,
開始ページ：151,
終了ページ：158, 1997年03月,
［査読有り］The coherent tunneling phenomenon is investigated in rectangular billiards divided into two domains by a classically unclimbable potential barrier. We show that by placing a pointlike scatterer inside the billiard, we can control the occurrence and the rate of the resonance tunneling. The key role of the avoided crossing is stressed.
Keywords: chaotic tunneling, quantum billiard, delta potential, diabolical degeneracy PACS: 3.65.-w, 4.30.Nk, 5.45.+b, 73.40.Gk
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0375-9601(97)00119-9DOI ID：10.1016/S0375-9601(97)00119-9,
ISSN：0375-9601,
CiNii Articles ID：80009570238 Flux String in Quantum Billiards with Two Particles Taksu Cheon; T. Shigehara
Physics Letters A,
巻：233,
号：1/2,
開始ページ：11,
終了ページ：16, 1997年03月,
［査読有り］We examine the quantum motion of two particles interacting through a contact force which are confined in a rectangular domain in two and three dimensions. When there is a difference in the mass scale of two particles, adiabatic separation of the fast and slow variables can be performed. Appearance of the Berry phase and magnetic flux is pointed out. The system is reduced to a one-particle Aharonov-Bohm billiard in two-dimensional case. In three dimension, the problem effectively becomes the motion of a particle in the presence of closed flux string in a box billiard.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/S0375-9601(97)00439-8DOI ID：10.1016/S0375-9601(97)00439-8,
ISSN：0375-9601,
CiNii Articles ID：80009837613 Scale Anomaly and Quantum Chaos in the Billiards with Pointlike Scatterers Taksu Cheon; Takaomi Shigehara
Physical Review E,
巻：54,
号：4,
開始ページ：3300,
終了ページ：3303, 1996年12月,
［査読有り］We argue that the random-matrix like energy spectra found in pseudointegrable billiards with pointlike scatterers are related to the quantum violation of scale invariance of classical analogue system. It is shown that the behavior of the running coupling constant explains the key characteristics of the level statistics of pseudointegrable billiards.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevE.54.3300DOI ID：10.1103/PhysRevE.54.3300,
ISSN：1063-651X,
CiNii Articles ID：80009307993,
PubMed ID：9965474 Wave Chaos in Quantum Billiards with a Small but Finite-Size Scatterer T Shigehara; T Cheon
Physical Review E,
巻：54,
号：2,
開始ページ：1321,
終了ページ：1331, 1996年08月,
［査読有り］We study the low-energy quantum spectra of two-dimensional rectangular billiards with a small but finite-size scatterer inside. We start by examining the spectral properties bf billiards with a single pointlike scatterer: The problem is formulated in terms of the self-adjoint extension theory of functional analysis: The condition for the appearance of so-called wave chaos is clarified. We then relate the pointlike scatterer to a finite-size scatterer through an appropriate truncation of the basis. We show that the signature of wave chaos in low-energy states is most prominent when the scatterer is weakly attractive. As an illustration, numerical results of a rectangular billiard with a small rectangular scatterer inside are exhibited.
AMERICAN PHYSICAL SOC, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevE.54.1321DOI ID：10.1103/PhysRevE.54.1321,
ISSN：1063-651X,
CiNii Articles ID：80009156316,
PubMed ID：9965201,
Web of Science ID：WOS:A1996VD67400046 Geometric Phase in Quantum Billiards with a Pointlike Scatterer T. Cheon; T. Shigehara
Physical Review Letters,
巻：76,
号：11,
開始ページ：1770,
終了ページ：1773, 1996年03月,
［査読有り］We examine the quantum energy levels of rectangular billiards with a pointlike scatterer in one and two dimensions. By varying the location and the strength of the scatterer, we systematically find diabolical degeneracies among various levels. The associated Berry phase is illustrated, and the existence of localized wave functions is pointed out. In one dimension, even the ground state is shown to display the sign reversal with a mechanism to circumvent the Sturm-Liouville theorem.
AMERICAN PHYSICAL SOC, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevLett.76.1770DOI ID：10.1103/PhysRevLett.76.1770,
ISSN：0031-9007,
CiNii Articles ID：80008836716,
PubMed ID：10060516,
Web of Science ID：WOS:A1996TZ28200002 Irregular Scattering with Complex Target Taksu Cheon; Takaomi Shigehara; Naotaka Yoshinaga
Progress of Theoretical Physics,
巻：93,
号：2,
開始ページ：483,
終了ページ：488, 1995年,
［査読有り］The one-dimensional scatterings by a target with two internal degrees of freedom are investigated. The damping of resonance peaks and the associated appearance of fluctuating background found in the quantum inelastic amplitudes are related to the disorderly reaction function in the analog classical system.
一般社団法人日本物理学会, 英語
DOI：https://doi.org/10.1143/PTP.93.483DOI ID：10.1143/PTP.93.483,
ISSN：0033-068X,
CiNii Articles ID：110001205869 Conditions for the Appearance of Wave Chaos in Quantum Singular Systems with a Pointlike Scatterer T. Shigehara
Physical Review E,
巻：50,
号：6,
開始ページ：4357,
終了ページ：4370, 1994年,
［査読有り］AMERICAN PHYSICAL SOC, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevE.50.4357DOI ID：10.1103/PhysRevE.50.4357,
ISSN：1063-651X,
CiNii Articles ID：80008029348,
PubMed ID：9962517,
Web of Science ID：WOS:A1994QA10800014 Nuclear Mass Dependence of Chaotic Dynamics in Ginocchio Model Naotaka Yoshinaga; Nobuaki Yoshida; Takaomi Shigehara; Taksu Cheon
Physical Review C,
巻：48,
号：2,
開始ページ：R509,
終了ページ：R512, 1993年02月,
［査読有り］The chaotic dynamics in nuclear collective motion is studied in the framework of a schematic shell model which has only monopole and quadrupole degrees of freedom. The model is shown to reproduce the experimentally observed global trend toward less chaotic motion in heavier nuclei. The relation between current approach and the earlier studies with bosonic models is discussed.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevC.48.R509DOI ID：10.1103/PhysRevC.48.R509,
ISSN：0556-2813,
CiNii Articles ID：80007217097,
PubMed ID：9968921 Level-Spacing Distribution of a Singular Billiard T. Shigehara; N. Yoshinaga; Taksu Cheon; T. Mizusaki
Physical Review E,
巻：47,
号：6,
開始ページ：R3822,
終了ページ：R3825, 1993年,
［査読有り］In this paper, we examine the level-spacing distribution P(S) of the rectangular billiard with a single pointlike scatterer, which is known as almost integrable. It is shown that the observed P(S) is a new type, which is quite different from the previous conclusion. Even in the strong-coupling limit, the Poisson-like behavior rather than Wigner-like behavior is seen for S1, although the level repulsion still remains in the small-S region. The difference from the previous works is analyzed in detail. © 1993 The American Physical Society.
英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevE.47.R3822DOI ID：10.1103/PhysRevE.47.R3822,
ISSN：1063-651X,
SCOPUS ID：5544324406 Chaos and Symmetry in the Interacting Boson Model
T. Mizusaki; N. Yoshinaga; T. Shigehara; T. Cheon
Physics Letters B, 巻：269, 号：1-2, 開始ページ：6, 終了ページ：12, 1991年, ［査読有り］
The level spectra of the interacting boson model for the whole range of parameters which span over three dynamical symmetries are analyzed in terms of the nearest-neighbour level-spacing distribution, and the "quantum chaos map" is charted. Strongly chaotic level spectra are seen in between SU (3) and O (6) symmetries. Unexpected persistence of Poisson statistics is found along the line connecting U (5) and O (6) symmetries. We argue that this is to be identified with the Berry-Robnik distribution with high division number arising from the preserved O (5) subsymmetry.
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
ISSN：0370-2693, Web of Science ID：WOS:A1991GN32900002
Signature of Chaos in Quantum Pseudointegrable Billiard T. Cheon; T. Mizusaki; T. Shigehara; N. Yoshinaga
Physical Review A,
巻：44,
号：2,
開始ページ：R809,
終了ページ：R812, 1991年,
［査読有り］英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1103/PhysRevA.44.R809DOI ID：10.1103/PhysRevA.44.R809,
ISSN：1050-2947,
CiNii Articles ID：80006027678,
PubMed ID：9906101 Isoscalar Spin Response Functions in the Quasielastic Scattering Region
T. Shigehara; K. Shimizu; A. Arima
Nuclear Physics A, 巻：510, 号：1, 開始ページ：106, 終了ページ：124, 1990年, ［査読有り］
ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
ISSN：0375-9474, Web of Science ID：WOS:A1990CY72700005
The Continuum RPA with the Exchange Term Explicitly Included and Its Application to the Spin-Isospin and Longitudinal Response Functions T. Shigehara; K. Shimizu; A.Arima
Nuclear Physics A,
巻：492,
号：3,
開始ページ：388,
終了ページ：410, 1989年,
［査読有り］ELSEVIER SCIENCE BV, 英語, 研究論文（学術雑誌）
DOI：https://doi.org/10.1016/0375-9474(89)90404-1DOI ID：10.1016/0375-9474(89)90404-1,
ISSN：0375-9474,
CiNii Articles ID：80004438249,
Web of Science ID：WOS:A1989U325300002 The Isovector Spin Response in a Finite Nucleus T. Shigehara; K. Shimizu; A. Arima
Nulcear Physics A,
巻：477,
号：4,
開始ページ：583,
終了ページ：595, 1988年,
［査読有り］DOI：https://doi.org/10.1016/0375-9474(88)90407-1DOI ID：10.1016/0375-9474(88)90407-1,
ISSN：0375-9474,
CiNii Articles ID：80003792279
