Hasebe K.,Sendai National College of Technology
International Journal of Modern Physics A | Year: 2016
Noncommutative geometry naturally emerges in low energy physics of Landau models as a consequence of level projection. In this work, we proactively utilize the level projection as an effective tool to generate fuzzy geometry. The level projection is specifically applied to the relativistic Landau models. In the first half of the paper, a detail analysis of the relativistic Landau problems on a sphere is presented, where a concise expression of the Dirac-Landau operator eigenstates is obtained based on algebraic methods. We establish SU(2) "gauge" transformation between the relativistic Landau model and the Pauli-Schrödinger nonrelativistic quantum mechanics. After the SU(2) transformation, the Dirac operator and the angular momentum operators are found to satisfy the SO(3, 1) algebra. In the second half, the fuzzy geometries generated from the relativistic Landau levels are elucidated, where unique properties of the relativistic fuzzy geometries are clarified. We consider mass deformation of the relativistic Landau models and demonstrate its geometrical effects to fuzzy geometry. Super fuzzy geometry is also constructed from a supersymmetric quantum mechanics as the square of the Dirac-Landau operator. Finally, we apply the level projection method to real graphene system to generate valley fuzzy spheres. © 2016 World Scientific Publishing Company.
Uchida T.,Sendai National College of Technology
Japanese Journal of Applied Physics | Year: 2014
Electronic displays, especially liquid crystal displays (LCDs), have made significant progress. In this paper, the actual situation of how the research and development of the new field was pushed forward is introduced by referring to the process of liquid crystal study related to the author's experience. In addition, the future trends of research and development on image electronics are discussed on the basis of the peculiar characteristics of humans related to information input and output ability. © 2014 The Japan Society of Applied Physics.
Kitamura H.,Toyota Technological Institute |
Sekido M.,Sendai National College of Technology |
Takeuchi H.,Toyota Central R&D Labs. |
Ohno M.,Toyota Technological Institute
Carbon | Year: 2011
Surface functionalization of single-walled carbon nanotubes (SWCNTs) was carried out using fuming nitric acid as a NO2 radical source. The surface double bonds of the SWCNTs reacted with the NO2 radicals at 10-90 °C under sonication, and following treatment with aqueous NaOH yielded modified carbon nanotubes with high affinity for polar solvents such as dimethylformamide. The structure of the product was characterized using Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and atomic force microscopy. FT-IR and XPS spectra revealed the product has OH groups (3400, 1200 cm -1), which was expected due to the addition of NO2 radicals to the surface double bonds and subsequent substitution with OH groups. C1s curve fitting analysis of the XPS spectra was used to quantitatively determine the different functional groups on the surface, and the amount of COOH groups was found to be increased from 2.8% to 9.3% due to progressive oxidation by increasing the reaction temperature from 10 to 90 °C. © 2011 Elsevier Ltd. All rights reserved.
Itoh M.,Sendai National College of Technology
2010 International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2010 | Year: 2010
In the field of industrial machines, the mechanical systems composed of the power circulation structure exist, and the powers of two or more motors of the same output are synthesized through the gear stages to drive the driven machine part and the desired motion of the machine is achieved. In this paper, the case that the power circulation mechanism is driven by two motors is taken up. First, the analytical model for the torsional vibration and the analytical result are shown. Second, the suppression effects on the residual vibration generated in the driven machine part when motors start and stop by applying the model-based control concerning the velocity control loop is confirmed by the simulation. Simulations show satisfactory control results to reduce the transient vibration at the driven machine part. © 2010 IEEE.
Matsueda H.,Sendai National College of Technology |
Ishihara M.,Tohoku University |
Hashizume Y.,Tokyo University of Science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013
A tensor-network variational formalism of thermofield dynamics is introduced. The formalism relates the original Hilbert space with its tilde space by a product of two copies of a tensor network. Then, their interface becomes an event horizon, and the logarithm of the tensor rank corresponds to the black hole entropy. Eventually, a multiscale entanglement renormalization ansatz reproduces an anti-de Sitter black hole at finite temperature. Our finding shows rich functionalities of multiscale entanglement renormalization ansatz as efficient graphical representation of AdS/CFT correspondence. © 2013 American Physical Society.
Itoh M.,Sendai National College of Technology
2013 IEEE International Conference on Mechatronics and Automation, IEEE ICMA 2013 | Year: 2013
In the field of industrial machines, the mechanical systems composed of the power circulation structure exist, and the powers of two or more motors of the same output are synthesized through the gear stages to drive the driven machine part and the desired motion of the machine is achieved. In this paper, the case that the power circulation mechanism is driven by two motors is taken up. First, the analytical model for the torsional vibration and the analytical results are shown. Second, a model-based control related to the velocity control loop is proposed. Third, the suppression effects on the residual vibration generated in the driven machine part when motors start and stop by applying the model-based control integrated into the position control loop is confirmed by simulations. Simulations show satisfactory control results to reduce the transient vibration at the driven machine part. © 2013 IEEE.
Nakayama T.,Hokkaido University |
Kaneshita E.,Sendai National College of Technology
Journal of the Physical Society of Japan | Year: 2011
We show that the distinct differences of low-lying THz-frequency dynamics between type-I clathrates with on-center and off-center guest ions naturally follow from a theoretical model taking into account essential features of the dynamics of rattling guest ions. Our model analysis demonstrates the drastic change from the conventional dynamics shown by on-center systems to the peculiar dynamics of off-center systems in a unified manner. We claim that glasslike plateau thermal conductivities observed for off-center systems stem from the flattening of acoustic phonon dispersion in the regime |k| lt; |G|/4. The mechanism is applicable to other systems such as glasses or relaxers. © 2011 The Physical Society of Japan.
Matsueda H.,Sendai National College of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012
In quantum spin chains at criticality, two types of scaling for the entanglement entropy exist: one comes from conformal field theory (CFT), and the other is for entanglement support of matrix product state (MPS) approximation. On the other hand, the quantum spin-chain models can be mapped onto two-dimensional (2D) classical ones by the Suzuki-Trotter decomposition. Motivated by the scaling and the mapping, we introduce information entropy for 2D classical spin configurations as well as a spectrum, and examine their basic properties in the Ising and the three-state Potts models on the square lattice. They are defined by the singular values of the reduced density matrix for a Monte Carlo snapshot. We find scaling relations of the entropy compatible with the CFT and the MPS results. Thus, we propose that the entropy is a kind of "holographic" entanglement entropy. At T c, the spin configuration is fractal, and various sizes of ordered clusters coexist. Then, the singular values automatically decompose the original snapshot into a set of images with different length scales, respectively. This is the origin of the scaling. In contrast to the MPS scaling, long-range spin correlation can be described by only few singular values. Furthermore, the spectrum, which is a set of logarithms of the singular values, also seems to be a holographic entanglement spectrum. We find multiple gaps in the spectrum, and in contrast to the topological phases, the low-lying levels below the gap represent spontaneous symmetry breaking. These contrasts are strong evidence of the dual nature of the holography. Based on these observations, we discuss the amount of information contained in one snapshot. © 2012 American Physical Society.
Drollette E.S.,University of Illinois at Urbana - Champaign |
Shishido T.,Sendai National College of Technology |
Pontifex M.B.,University of Illinois at Urbana - Champaign |
Hillman C.H.,University of Illinois at Urbana - Champaign
Medicine and Science in Sports and Exercise | Year: 2012
OBJECTIVE: The present study evaluated the effects of an acute bout of moderate-intensity treadmill walking on aspects of cognitive control underlying successful academic achievement. METHODS: The study used a within-subjects counterbalanced design with a sample of 36 preadolescent children. Cognitive performance was assessed using a modified flanker task and a modified spatial n-back task to assess inhibition and working memory, respectively. RESULTS: No changes in task performance were observed while individuals were actively walking or at seated rest across both tasks. However, during the flanker task, increased response accuracy was observed after exercise relative to post-seated rest. Further observation revealed decrements to response accuracy after seated rest relative to baseline. No such effect was observed for the n-back task. CONCLUSIONS: These findings suggest selective exercise-induced changes to cognitive control for aspects of inhibitory control and attention but not for working memory. Furthermore, the findings suggest that short bouts of exercise may be efficacious for maintaining cognitive performance, which may have implications for scholastic achievement. Copyright © 2012 by the American College of Sports Medicine.
Takabatake T.,Hiroshima University |
Suekuni K.,Hiroshima University |
Nakayama T.,Max Planck Institute for the Physics of Complex Systems |
Nakayama T.,Tongji University |
And 2 more authors.
Reviews of Modern Physics | Year: 2014
Type-I clathrate compounds have attracted a great deal of interest in connection with the search for efficient thermoelectric materials. These compounds constitute networked cages consisting of nanoscale tetrakaidecahedrons (14-hedrons) and dodecahedrons (12-hedrons), in which the group-1 or -2 elements in the periodic table are encaged as so-called rattling guest atoms. It is remarkable that, although these compounds have a crystalline cubic structure, they exhibit glasslike phonon thermal conductivity over the whole temperature range depending on the states of rattling guest atoms in the tetrakaidecahedron. In addition, these compounds show unusual glasslike specific heats and terahertz-frequency phonon dynamics, providing a remarkable broad peak almost identical to those observed in amorphous materials or structural glasses, the so-called boson peak. An efficient thermoelectric effect is realized in compounds showing these glasslike characteristics. In this decade, a number of experimental works dealing with type-I clathrate compounds have been published. These are diffraction, thermal, and spectroscopic experiments in addition to those based on heat and electronic transport. These form the raw materials for this review based on advances from this decade. The subject of this review involves interesting phenomena from the viewpoint not only of physics but also of the practical problem of elaborating efficient thermoelectric materials. This review presents a survey of a wide range of experimental investigations of type-I clathrate compounds, together with a review of theoretical interpretations of the peculiar thermal and dynamic properties observed in these materials. © 2014 American Physical Society.