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Nagoya, Japan

Daido University is a private university in Minami-ku, Nagoya, Aichi Prefecture, Japan. The predecessor of the school was founded in 1939. The school is close to Daidōchō Station. Wikipedia.

This paper consists of three parts. In the first part, we prove that the Bekenstein-Hawking entropy is the unique expression of black hole entropy. Our proof is constructed in the framework of thermodynamics without any statistical discussion. In the second part, intrinsic properties of quantum mechanics are shown, which justify the Boltzmann formula to yield a unique entropy in statistical mechanics. These properties clarify three conditions, one of which is necessary and others are sufficient for the validity of Boltzmann formula. In the third part, by combining the above results, we find a reasonable suggestion from the sufficient conditions that the potential of gravitational interaction among microstates of underlying quantum gravity may not diverge to negative infinity (such as Newtonian gravity) but is bounded below at a finite length scale. In addition to that, from the necessary condition, the interaction has to be repulsive within the finite length scale. The length scale should be Planck size. Thus, quantum gravity may become repulsive at Planck length. Also, a relation of these suggestions with action integral of gravity at semi-classical level is given. These suggestions about quantum gravity are universal in the sense that they are independent of any existing model of quantum gravity. © 2011 by the author.

The ductile fracture of nonferrous pure metals and alloys during notch tensile testing was predicted using an ellipsoidal void model. Simulated and experimental tensile tests were performed using four types of nonferrous sheets and bars. Two magnitudes of prestrain were induced in the sheets by rolling and in the bars by drawing. Six notched sheet specimens and thirteen notched bar specimens with different notch-root radii were prepared. A void configuration and void shape for pure metals and those for alloys were assumed. The effects of the prestrain and notch-root radius on the reduction in area calculated agreed reasonably well with those obtained experimentally. © 2015 Elsevier Ltd.

The n-dimensional homogeneous Lotka-Volterra (HLV) ladder equation possesses Lie symmetries that generate a Lie algebra isomorphic to sl n(K) [J. Phys. Soc. Jpn. 71 (2002) 2396 and 72 (2003) 973], where K = C or R. In this work, using the Lie algebraic structure of the HLV ladder equation, we derive new n-dimensional dynamical systems and prove their integrability from the viewpoint of Lie symmetries. © 2013 The Physical Society of Japan.

Imai K.,Daido University
Journal of the Physical Society of Japan | Year: 2014

In this paper, a new n-dimensional homogeneous Lotka-Volterra (HLV) equation, which possesses a Lie symmetry, is derived by the extension from a three-dimensional HLV equation. Its integrability is shown from the viewpoint of Lie symmetries. Furthermore, we derive dynamical systems of higher order, which possess the Lie symmetry, using the algebraic structure of this HLV equation. © 2014 The Physical Society of Japan.

Komori K.,Daido University
Computational Materials Science | Year: 2013

A void model that can be used for the evaluation of ductile fracture in the simulation of sheet metal-forming processes is proposed. This void model is an extension of the Thomason model of void coalescence, which is based on the internal necking of the matrix between voids. In sheet metal-forming processes, the material is subjected to a complex strain path. Hence, the prestrain should be considered for the evaluation of ductile fracture in the simulation of sheet metal-forming processes. In the present paper, the prestrain is first introduced in the proposed void model. The simulation of the hole expansion test, which is a fundamental material test in sheet metal forming, is performed while paying special attention to the void configuration and the void shape. Finally, the validity of the proposed void model is confirmed by comparing the simulation results with the experimental results. © 2011 Elsevier B.V. All rights reserved.

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