Previous studies have indicated that pouch volume and stoma size are two important factors related to weight loss after laparoscopic gastric banding in morbid obese patients. A numerical pouch model with variable pouch volume and stoma size was generated and the mass flow of filling and emptying of the pouch was simulated numerically. There was an overall qualitative agreement on the volume change between the simulated results and the clinical recording. Increasing the pouch volume caused a decrease of the maximum circumferential stress and the maximum longitudinal stress in the pouch wall at the same degree of filling. Decreasing the stoma diameter caused an increase of the maximum circumferential stress and a decrease of the maximum longitudinal stress. Both the pouch volume and stoma size are important determinants of mechanical wall stress, wall strain and pouch emptying and hence may affect satiety and weight loss.

View full abstract

In the paper, a two-dimensional model of water transport across the whole cell are presented for the proton exchange membrane fuel cell. The modeling domain consists of the gas channels, gas diffusion layers, catalyst layers and the proton exchange membrane. The numerical results implies that it is very necessary to investigate the interaction effecting between the component of the fuel cell in order to predict correctly the coupled transport phenomena occurred in the whole fuel cell.. The boundary condition between the catalyst layer and gas diffusion layer is investigated, too

View full abstract

[in Japanese]

View full abstract

In this study, a two-layer model is developed for simulating the homogenized elastic-viscoplastic behavior of plate-fin structures. This model consists of plate and fin layers. which are individually ruled by macroscopic constitutive models. An anisotropic, compressible power-law equation that was derived in a recent study by the present authors is used to describe the homogenized viscoplastic behavior of fin layers. On the other hand, an isotropic. incompressible power-law equation is used as the macroscopic constitutive equation of plate layers. The two-layer model developed is applied to an ultra-fine plate-fin structure made of Hastelloy X at 900℃. It is thus shown that the two-layer model is more successful especially under combined loading than the corresponding one-layer model in which plates and fins are non-separately modeled.

View full abstract

In this study. the elastic-viscoplastic properties of ultra tine plate-fin structures with laminate misalignment are investigated using the time-dependent homogenization theory'. For this, it is first shown that, even though plate-fin structures have laminate misalignment, the distribution of perturbed velocity in the structures possesses periodicity. It is further shown that, by employing this periodicity as a boundary condition for boundary value problems, a rectangular unit cell defined for a plate-fin structure with no laminate misalignment can be also used as the analysis domain for the homogenization analysis of plate-fin structures with laminate misalignment. The present method is then applied to the analysis of the elastic-viscoplastic behavior and compressibility of ultra fine plate-fin structures made of Ni-based alloy, under uniaxial tension at high temperature. It is shown that the laminate misalignment can significantly affect both the elastic-viscoplastic behavior and compressibility of the plate-fin structures.

View full abstract

This paper presents the evaluation method of approximate equivalent stiffnesses for structural optimization of double-skin hollowed plates. For this purpose, the equivalent stiffliesses of the plate are given first in the second-order polynomial form with respect to design parameters by using the Response Surface Method (RSM). Finite element analysis for bending problem is formulated by using the ACM rectangular element, and then FEA program is developed by incorporating the equivalent stiffliesses estimated by RSM. Finally the numerical results by the present FEA are compared with the ones by a commercial FEA code, ANSYS, and the applicability of the approximate equivalent stiffnesses and the present FEA are studied

View full abstract

In this paper, we present a free-form optimization method for designing shell's form in order to control the vibration mode at a prescribed frequency to a target mode. With the free-form optimization method, an optimum shell with smooth free-form surface can be obtained without any shape parameterization. We introduce a squared displacements error norm at the prescribed surface as the objective functional to control the vibration mode to a desired one in a frequency response problem. It is assumed that the shell was varied in the normal direction to the surface and the thickness is constant. A non-parametric shape optimization problem is formulated, and the shape gradient function is theoretically derived using the material derivative method. The shape gradient function is applied to the shell surface as the pseudo traction force to vary the form. The calculated results show the effectiveness of the proposed method for the optimal free-form design of shell structures aiming at mode control.

View full abstract

Organic light emitting diode (OLED) used for lighting is utilized as display of television, mobile phone, digital cameri and soon. Luminescence spectrum of light from OLED structure depends on optical indexes and film thickness of the thin films. The structural optimization of thin films is useful to satisfy a design specification. Since the design of OLED structure is result in a combinatorial optimization, it is difficult to find a design solution. We developed the system which could optimize optical indexes and film thickness of each layer simultaneously by genetic algorithm. In this paper, we report results of the optimization of OLED to control the luminescence spectrum.

View full abstract

[in Japanese]

View full abstract

In this paper, we propose a new simple estimate for the width of the Gaussian kernel, based on the estimate proposed by Nakayama. First, the simple estimate for width proposed by Nakayama is analyzed, and then some sufficient conditions will be described. According to these sufficient conditions, a new simple estimate for the width of the Gaussian kernel is proposed. Considering the equivalence between some machine learning techniques, it is expected that the proposed estimate of the width is applicable to wide range of machine learning techniques employing the Gaussian kernel. Through numerical examples, the validity of the proposed estimate of the width is examined.

View full abstract