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Studies the structure formation of short chain molecules consisting of CH[sub 2] groups using molecular dynamics simulations. Formation of the structures from a random configuration by quenching; Growth process of the local orientationally-ordered domains; Parallel ordering of the chain molecules; Evidence of chain sliding diffusion in the hexagonal phase.

Reports on the structural formation of a single polymer chain using molecular dynamics simulations. Formation of bond-orientationally ordered structure at low temperatures from a random-coil structure at high temperatures; Growth of the anisotropy of a polymer chain during the growth of the bond-orientational order.

A central theme of ``Complexity?? is the question of the creation of ordered structure in nature (self-organization). The assertion is made that self-organization is governed by three key processes, i.e., energy pumping, entropy expulsion and nonlinearity. Extensive efforts have been done to confirm this assertion through computer simulations of plasmas. A system exhibits markedly different features in self-organization, depending on whether the energy pumping is instantaneous or continuous, or whether the produced entropy is expulsed or reserved. The nonlinearity acts to bring a nonequilibrium state into a bifurcation, thus resulting in a new structure along with an anomalous entropy production. As a practical application of our grand view of self-organization a preferential generation of a dipole magnetic field is successfully demonstrated. [ABSTRACT FROM AUTHOR]

The energy conversion process as well as the plasma heating mechanism in the starting-up phase of driven reconnection is investigated in detail using two-dimensional magnetohydrodynamic (MHD) simulation. It is revealed that the compressional heating effect is predominant in this phase rather than the Ohmic and the viscous heating. The predominance of the compressional heating means that the plasma flow energy is considerably converted to the thermal energy. The strong compression takes place in the process during which the fast shock is generated in the downstream region of the reconnection point. The plasma heating due to nonsteady reconnection is briefly discussed as a promising mechanism for the anomalous ion heating, which is observed in reversed-field pinch (RFP) experiments. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are carried out to study structure formation of a single polymer chain with 500 CH[sub 2] groups. Our simulations show that the orientationally ordered structure is formed at a low temperature both by gradual stepwise cooling and by quenching from a random configuration at a higher temperature. The growth of the global orientational order proceeds in a gradual manner in the case of gradual stepwise cooling, whereas it proceeds in a stepwise manner in the case of quenching. The latter feature endorses the previously proposed hypothetical grand view of self-organization [e.g., see T. Sato, Phys. Plasmas 3, 2135 (1996)]: when a system is driven far from equilibrium, it will evolve to a more stable state in a stepwise fashion irrespective of its fundamental interaction forces. From the microscopic analysis of the structure formation process, we find the following characteristic features: (i) In the case of gradual stepwise cooling, the global orientational order grows gradually through the incorporation of small trans domains and the surrounding trans segments into the largest trans domain. (ii) In the case of quenching, the growth of the orientational order is either due to the incorporation of small trans domains and the surrounding trans segments into the largest trans domain or to the elongation of the trans segments in the largest trans domain. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Nonlinear magnetohydrodynamic (MHD) simulations are executed to investigate the dynamical behavior of the relaxation phenomenon observed in spherical tokamak (ST) plasma that is known as the Internal Reconnection Event (IRE). The simulation results successfully reproduce several key features of IRE, and the physical mechanisms are revealed. A sudden collapse of the pressure profile takes place as a result of a nonlinear time development of a pressure-driven instability. A magnetic reconnection induced between the internal and the external magnetic field is found to play a crucial role in determining the nature of the overall process, namely, the rapid expulsion of the plasma heat energy due to the pressure imbalance along the reconnected field lines, and the large distortion in the overall shape. The resultant deformations in overall shape of the plasma are in good agreement with the experimental observations. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: A new simulation code of mantle convection in a three-dimensional spherical shell is presented. Major innovation of the code comes from an combination of two numerical techniques, namely Yin–Yang grid and ACuTE algorithm, which we had developed for large-scale simulations of solid earth sciences. Benchmark comparisons for the steady convection for low Rayleigh numbers (Ra) with previous calculations revealed that accurate results are successfully reproduced not only for isoviscous cases but also for the cases where the mild temperature-dependence of viscosity is included. We also demonstrated that our code can reproduce the change in convective flow patterns into the “sluggish-lid” regime with increasing the viscosity variation up to . [Copyright &y& Elsevier]

Abstract: A couple of orthogonal coordinates for dipole geometry are proposed for numerical simulations of plasma geophysics in the Earth''s dipole magnetic field. These coordinates have proper metric profiles along field lines in contrast to the standard dipole coordinate system that is commonly used in analytical studies for dipole geometry. [Copyright &y& Elsevier]