In the direct simulation Monte Carlo method (DSMC), it is shown that a widely used time counter (TC) scheme proposed by Bird gives inaccurate results for certain non-equilibrium distribution functions. The functions are defined in the text and include as an extreme case the distribution function of the cold counter-streaming flow. When the TC scheme is applied to these distribution functions it results in counting a rate of collision too largely, and there is consequently a corresponding error in advancing the simulation time. This effect appears in functions which differ from the equilibrium one by more than a certain threshold amount. The threshold is shown to depend on the number of particles being simulated, and increases with their number. That is, the applicability of the TC scheme increases with particle numbers. A new scheme based on the collision rate is proposed to overcome the difficulty with the TC scheme. The CPU time of the new scheme is proportional to the particle numbers and is comparable to both the TC scheme and the no-time counter scheme in computation efficiency.

The book aims to clarify from a demographic and geographical perspective how population trends of the Tohoku Region were changed as a result of the GEJED. The author shows how different the 2011 GEJED was from past disasters in this region with regard to the impacts on population change in the Tohoku Region. He explains how the recent disaster is different from past disasters, based on the theories of the first and second demographic transitions. He also clarifies the causality between the extent of housing damage and mortality through geographical analysis. Furthermore, this book shows how migration patterns were changed before and after the GEJED, and it identifies the differences between the areas affected by the tsunami and by the nuclear power plant accident. Investigating the GEJED as a case study, the book presents a method to analyze the relationship between natural disasters and population change. This book is especially useful for researchers inthe fields of disaster, environment, and population to better understand the relationship between the environment and population.

An experimental study of quasi-steady operation of repetitively-pulsed laser thruster was conducted by using Kr-F laser of 100 pps (pulse per second). The measured impulse coupling coefficient is comparable to the result previously reported and the theoretical value predicted by the transparent vapor model. The thrust level in a quasi-steady operation can be estimated as the impulse coupling coefficient multiplied by the average power of the laser beam, since the time in which the recoil momentum is delivered by each shot of laser beam is satisfactorily smaller than the laser pulse interval. The specific impulse is also measured. It is larger than the theoretical value predicted from the transparent vapor model. During a few thousand shots of laser, there was not much reduction in the impulse coupling coefficient at the present laser power of a few watts. The new configuration in which the thrust vector is anti-parallel to the laser beam is proposed and is demonstrated.

A method to obtain transport coefficients for systems simulated by the direct simulation Monte Carlo method is proposed using the fluctuation-dissipation theorem. Its application is demonstrated by determining the viscosity coefficient. To this end, the correlation function was calculated numerically in the equilibrium system modelled by the direct simulation Monte Carlo method. The viscosity coefficient was obtained by matching, in the collisional regime, the numerical correlation function with the theoretical one the viscosity coefficient being a free parameter. The viscosity so determined agrees well with the one given by the Chapman-Enskog method. The present method can also be used to obtain the other transport coefficients in much complex gases such as the one with multispecies.

A structured package for radiation analysis, SPRADIAN, is developed and its application is presented. This study is primarily motivated by necessity of a quantitative analysis of severe radiative environment which the MESES-C capsule encounters during its reentry into the earth atmosphere. In comparison with other radiation programs, much attention is paid to extension of the temperature range up to 100,000 K, detailed treatment of UV and VUV radiation, and flexibility with applications. Incorporated into the programs are the bound-bound, bound-free, and free-free radiation from monatomic and diatomic species. The bound-bound radiation is calculated by the line-by-line method, while the others are computed using corresponding cross-sections which are evaluated by the quantum defect method. Two approximate models are introduced to integration of the radiative heat transfer equation over the shock layer in order to evaluate the radiative heat flux. Accuracy of the program is discussed, and the application to the MUSES-C radiation analysis is presented briefly.

The wake flow field behind the EXPRESS capsule at supersonic speeds is studied experimentally in the wind tunnel. The schlieren photographs and the measurements of the Pitot pressure and the static pressure in the wake clarify the structure of the wake flow field and the effects of the freestream Mach number on it. The wake structure is classified into two types, that is, the subsonic wake neck type and the supersonic wake neck type. The flow characteristics of each wake neck type are discussed. From a viewpoint of the parachute deployment, the effects of the freestream Mach number on the dynamic pressure in the wake are investigated. The recovery ratio of the dynamic pressure in the wake increases with the decrease in the Mach number. At lower Mach number, however, the recovery is delayed due to the extension of the recirculating region behind the capsule bottom. The numerical simulations of the wake flow field are carried out by solving the laminar Navier-Stokes equations and it is pointed out that the recovery of the flow velocity and the dynamic pressure may be enhanced significantly by the turbulent transition on the wake trail.