Recent advancement in parallel computing enables the precise finite element analysis of steel frames using solid elements. However, the finite element models used in the analysis have not been verified sufficiently. In this study, first, static finite element elastic-plastic buckling analyses of a square steel tube column subjected to a prescribed lateral displacement are performed with different meshes in order to verify the analysis model. It is shown that the accuracy and computation time of the analysis depend not only on the number of mesh divisions but also on the aspect ratio of each finite element. Then, dynamic elastic-plastic buckling analyses are performed for different meshes and different time increments. In the dynamic buckling problem, which is a kind of slow dynamics problem, accurate results can be obtained using a fine mesh but with a rather large time increment.
As a Lagrangian meshfree method, the MPS(Moving Particle Semi-implicit) method has been shown useful in engineering applications widely. In this paper, by using the Taylor series expansion, generalized schemes for any order spatial derivatives with higher order consistency, convergence, and completeness conditions are developed. Applying new schemes for numerical tests, calculating first and second derivatives of linear and non-linear functions, demonstrates higher order convergence regardless of whether particles are distributed regularly or randomly spread involving domain boundaries. Furthermore, application of new spatial derivative schemes enhances computational accuracy and stability for numerical analysis of incompressible flow with the free surface.
A welding process simulation considering the weld pool and dropped metal during welding which have a fluid flow with thermal conduction and a free surface is performed by using the hybrid particle and grid method with Explicit MPS. In this study, first, the applicability of Explicit MPS to the welding process is studied. Second, a hybrid particle and grid method is developed. In the hybrid method, particles can be used in the weld pool and the area located near the weld pool, while grid elements are used in the other areas. For high-speed simulation of the weld pool, all of calculation processes are parallelized and accelerated by a GPU (CUDA). The welding process simulation using the hybrid method can reduce the calculation cost reasonably within 1 to 2 % accuracy or so on.
トポロジー最適化は，構造形状の最適なレイアウトを探索する主要な設計手法のひとつである．多目的トポロジー最適化問題においては，その適用の容易さから，目的関数を重み付き線形和手法（Weighted sum method）によって単一目的化したSIMP(Solid Isotropic Material with Penalization)法が広く用いられる．SIMP法は目的関数の感度を用いる手法であるため，計算効率が高いが，多峰性が強い設計空間の場合，設計パラメータや解析メッシュの設定方法等により異なるトポロジー最適解が得られ，一義的な解が得られない問題点がある．このため，グローバルかつロバストな探索が可能な遺伝的アルゴリズム(Genetic algorithm)の適用が注目されるが，GAは高計算コストになる問題がある．そこで本研究では，GAを用いた多目的トポロジー最適化計算を高効率化するため，重み付き線形和手法を用いたSIMP法から得られた局所最適解（エリート）と類似する個体を複数生成し，それらをGAの初期集団として用いる手法を提案する．SIMP法から得られた代表的な最適解のトポロジーと類似するエリートトポロジー解を初期集団としてGAをスタートさせることで，GAの計算効率の向上に加え，グローバルなパレート解群が得られる可能性が期待される．本研究では，提案手法の有効性について検証するために，GAの初期集団をランダムに発生する従来手法とエリート初期集団を用いる提案手法の収束性および安定性を比較検討した．
Adiabatic quantum computation has been proposed as quantum parallel processing with adiabatic evolution by using a superposition state to solve combinatorial optimization problem, then it has been applied to many problems like satisfiability problem. Among them, Deutsch and Deutsch-Jozsa problems have been tried to be solved by using adiabatic quantum computation. In our previous paper, it has been shown that the adiabatic quantum computation in Deutsch problem is modified by using a cubic step function instead of a linear step parameter. In this paper, it is proposed to solve Bernstein-Vazirani problem more efficiently by the same cubic method to obtain a solution with higher observation probability of 99.6%.