Yuji Enomoto

Computer simulation of a two-dimensional type-II superconductor in a magnetic field

The authors study the time-dependent behaviour of type-II superconductors in an external magnetic field. Based on the time-dependent Ginzburg-Landau equation, simulations for several situations are performed in tow dimensions in order that they might discuss the dynamical behaviour of magnetic flux structures.

The magnetization process in type-II superconducting film

The authors numerically solve the time-dependent Ginzburg-Landau equation for a homogeneous, isotropic type-II superconducting film in the presence of an external magnetic field. They study the dynamical processes of the magnetization by stepwise change of the external field. It is demonstrated that the magnetic vortices penetrate and are expelled from the system boundary in accord with the change of the field, and the dynamical instability of magnetic flux wall near the boundary leads to the formation of a vortex at low fields. The hysteresis loop of magnetization versus the external field is also obtained.

Insect Feeding Inhibitors in Plants:Part I. Isolation of Three New Sesquiterpenoids in Parabenzoin trilobum Nakai

Three new sesquiterpenoids were isolated from Parabenzoin trilobum Nakai as feeding inhibitors against a polyphagous insect, Spodoptera littoralis Boisd and an oligophagous insect, Trimeresia miranda Butler. Host selection of polyphagous insects is also discussed.

Dynamics of a vortex line in type-II superconductors

The authors numerically study the dynamics of a vortex line in type-II superconductors which is driven by vortex line tension, external driving force, pinning force and thermal fluctuations. Based on the local stochastic differential equation for the vortex motion, computer simulations are performed within the planar approximation (no torsion) to investigate the pinning time, which is the time for the vortex line to overcome the pinning centre.

Many-body effects on the coarsening of grain boundary precipitates

The authors study the asymptotic behaviour of a diffusion-controlled coarsening of grain boundary precipitates. Using an analogy to two-dimensional particle coarsening, they consider cooperative effects among precipitates occurring via the diffusion field. They discuss the finite volume fraction effects on the form of the precipitate size distribution function and the coarsening rate.

The multi-nuclei growth equation for a vacuum-deposited thin films

The authors study the early stage behaviour of nucleus growth in a vacuum-deposited thin film. Solving a stationary diffusion equation with boundary conditions on each nuclei periphery they derive for the first time the multi-nuclei growth equation. This equation is found to express the cooperative interactions among nuclei via the diffusion field. They also examine a linear stability of a growing nucleus for many nuclei systems.

Dynamics of domain growth in degenerate conserved and non-conserved systems

The authors numerically study the time-dependent behaviour of domain growth in quenched systems with multiply degenerate ordered states. Based on the phenomenological model equations for such degenerate systems recently proposed by Enomoto et al. the authors perform two-dimensional computer simulations for triply degenerate systems both with a conserved and a non-conserved order parameter, respectively. In particular, they discuss the asymptotic scaling behaviour for the systems and the corresponding growth exponents for the characteristic length scales.

Computer simulations of discommensuration patterns

The authors study the dynamical behaviour of discommensuration patterns that have been observed in commensurate-incommensurate phase transitions. Using a method based on a phenomenological dynamics model proposed by Enomoto and Kato, two-dimensional simulations are performed to discuss the time evolution of the model system towards equilibrium states from the initial disordered state.

Dynamics of interacting flux kinks in layered high-Tc superconductors

The author has studied the dynamical behaviour of flux kinks, which appear in layered high-Tc superconductors when the magnetic field is parallel and slightly inclined to the plane of the layers. The author has obtained the equation of motion for flux kink position from the equation of motion for the displacement field of the flux line. Having performed computer simulations of the resulting equation the author discusses the time-dependent behaviour of the system with the initially random distributed kinks.