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Closed-loop production systems are used in many factories, e.g., machining, adhesive manufacturing, plastic forming and assembly factories. In these systems, many pallets, jigs or molds circulate and are used repeatedly, and the number affects the system production rate. In this paper, we analyze the effect of a number of pallets and system parameters on the production rate, and present the existence of the optimum number of pallets which yields the maximum production rate. Next, we propose an approximation method for estimating the optimum number of pallets, for which the estimation error is very small and the estimated number gives almost the same production rate as that yielded by the optimum number of pallets.

application/pdf, 論文(Article), We consider queueing systems with more than one assembly-like queues which are used for modelling assemly operation in production systems, and propose an approximation method to evaluate throughputs and stationary probabilities.

This paper describes an approximation method to estimate the system production rate of a machinging-assembly automatic production system connected by series machining Lines. In this method, the system is decomposed into 2-stage assembly systems, which are further decomposed into series lines with the assembly stage. Thus, the system production rate of any machining-assembly system can be estimated. It is shown that the estimated production rate agrees with the simulation result. Furthermore, this paper describes the effects of system parameters (numbers of assembly stages, machining lines and machining stages, and buffer capacities) on the production rate. The results show that operation probabilities of stages and buffer capacities affect the system production rate significantly, and that the increase in the number of parts assembled in each assembly stage has little effect on the production rate when the number of parts is large.

An approximation method is proposed to estimate the system production rate for an automatic merge machining-assembly production system in which L parts are machined in multi-stage series lines and are assembled. In this method, the system is decomposed into L series machining lines, each of which considers the parts delay occurring in other series machining lines. From the comparison between approximation and simulation results, it is found that the estimation error is very small. Furthermore, we study the effects of system parameters on the system production rate. The main results are as follows. (1) As the number of machining lines feeding assembly parts increases, the production rate decreases but the decrease becomes slight. (2) When the number of stages in machining lines is greater than two, the number of stages has little effect on the production rate.

3次元弾性論の基礎方程式にKirchhoff-Loveの仮定を適用することによって、外的負荷として温度変化と表面力の作用を同時に受ける多層積層円筒殻の弾性変形の支配方程式の1次近似表示が、面外変位に関する8階の微分方程式の形で導かれる。多層積層円筒殻の各層はそれぞれ異なる均質等方性材料から構成されているものとし、また、各層内では物性値は一定と仮定される。解析例として、軸対称熱変形問題の解が示される。, A governing equation for multi-layered cylindrical shells under combined thermal and mechanical loading is derived as a first approximation, consistent with the Kirchhoff-Love hypothesis, in the form of an eighth-order differential equation with respect to the lateral displacement. The shell structure is assumed to consist of homogeneous and isotropic layers having different material properties. It is also assumed that the material properties are constant for each layer. As an analytical example, the deformations and stresses of a multi-layered cylindrical shell under axisymmetric thermal load are analyzed., 資料番号: AA0004237000, レポート番号: NAL TR-1222

この論文は、原理と4つの具体例の解析からなる。原理では、互いに離れたいくつかの複素周波数をもった項に解を分解して解析している。この場合、基本解としては、ある一定の値の近くを時間と共に徐々に変化する複素周波数をもつ2つの項からなるものとしている。その目的は、物理的概念を明白化し、振動系と比較して大きな減衰率を持つ制御系への適用に対しても、計算を簡素化し、あわせて解をできうるかぎり定式化することである。, A nonlinear equation is analysed by dividing the solution into terms with different complex frequencies separated from each other. This is conducted in a manner where the complex frequencies in the two terms forming the fundamental solution have been assumed to vary slowly with time in the vicinity of certain constant frequencies. The purpose of the new method is to clarify the physical concept of each equation. For example, this aids in simplifying the analysis of a nonlinear control system in which the damping factor is extremely large in the vibrating system. Furthermore this method makes it possible to formulate many different solutions to any particular equation. In the four examples presented, equations are analysed utilizing a technique based on feedback theory, thus illustrating the method applied to a'real' physical concept., 資料番号: AA0004232000, レポート番号: NAL TR-1217