A lot of repeated work existed in the design of manufacturing process for similar parts, and many kinds of process knowledge which were not reused effectively contained in the historical process data. In these conditions, in order to reuse the typical process effectively and enhance design efficiency, typical process discovery was studied. The problem of typical process discovery was described firstly, the attributed directed graph was used to model the process. And the similarity between processes could be measured with the similarity between process cells and the similarity between process routes by the process model. Based on the process similarity, affinity propagation method was used to cluster the process. For the purpose of getting the effective clustering results and making sure the best number of clusters, the Silhouette index and the in-group proportion index were separately adopted in the clustering analysis. Finally, we have experimented the validity of the discovery algorithm by clustering typical process of machining process for satellite plate.
The coefficient of variation (CV) is an important quality parameter to measure the stability of the product quality. A variable two stage sampling plan based on the CV is developed in this paper when the quality characteristic follows normal distribution. The optimal plan parameters of the proposed variable two stage sampling plan are determined by minimizing the average sample number (ASN) using the two-point approach on the operating characteristic (OC) curve, and then tabulated for various combinations of acceptance quality level (AQL) and limiting quality level (LQL). The efficiency of the proposed variable two stage sampling plan is compared with the existing variable single sampling plan. The results show that the proposed plan has better performance than the single sampling plan in terms of ASN. Finally, the proposed plan is illustrated with a practical example.
In this paper we introduce a practical method to evaluate the reflectance of a layered turbid medium with a thin layer, which is not possible with the previous methods based on the diffusion theory. To this end, we employ two different reflectance models simultaneously. One is the newly improved 2-flux model for a thin layer and the other is the diffusion model for a thick layer. To combine the evaluation results from these two different models, we introduce a re-parameterization approach which makes these models compatible with each other. We verify that the proposed method yields robust performance by comparing with the Monte Carlo simulation. We also validate visual results and comparing the rendering time ours with other models.
Under growing concerns with sustainability in global and changing market, establishing a cooperative and competitive logistic is becoming a keen issue to provide manufacturing systems amenable to sales and operations planning. As a deployment for such practice, we have engaged in the various studies on logistics optimization. Especially, noticing that transportation cost and/or CO2 emission actually depend not only on distance but also loading weight (Weber basis), we have recently developed a few hybrid meta-heuristic methods for vehicle routing problems (VRP) and shown their effectiveness through numerical experiments. To the best of our knowledge, however, there exist no studies that take the Weber basis into account on VRP except for ours. As a hot interest in this area, we pay our attention on VRP with simultaneous pickup and delivery (VRPSPD). Then, this study attempts to extend the foregoing Weber basis study under single depot to multi-depot problem and intends to reveal some properties of VRPSPD. To work with such concerns, we have developed a novel hierarchical method comprised of a modified tabu search, a graph algorithm for the minimum cost flow problem and a Weber basis saving method. The proposed method is possible to solve various real world applications practically even with large problem sizes. Finally, the effectiveness of the proposed method is validated through numerical experiments taken place from various viewpoints to discuss about some peculiar features of VRPSPD.
In this study, we proposed two types of optimum trade-off charts considering mass variation for the design of a semi-active shock absorber and a passive shock absorber for landing gear. Each of these trade-off charts is formed from two curves indicating different types of data. Along one curve, the aircraft mass is constant, and shock absorbers having various dimensions are considered. Along the other curve, the aircraft mass varies from maximum to minimum values, and a specified shock absorber is considered. In order to generate optimum trade-off charts considering mass variation by means of a multi-objective optimization, we introduce a parameter related to the initial volume of gas inside the shock absorbers. We are able to establish and solve a multi-objective optimization problem and generate optimum trade-off charts considering mass variation. Using the optimum trade-off charts, we evaluate and compare the performance of semi-active and passive shock absorbers considering mass variation. It clearly demonstrates that the optimum trade-off charts are helpful in the design of landing gears for various aircrafts.
This paper presents a forecasting method for product different size production method, which is for the customers and company has different size requirement on single product design, based on multi-attribute decision making (MADM). Because of the forecast product production factor is complicated, so that first step will filter out the evaluation criteria of wheelset design through practical experiences of focus group, seven professional product designers. After filter out, the evaluation criteria are including maneuverability, manufacturability, style, creativity, and cost. We proposed to use grey number design evaluation to solve forecast product production problem, to set weights for evaluation criteria, and to takes wheelset series of product design for example to verify the method. Grey number design evaluation mainly uses grey numbers to represent the ideas of customers and designers, and then uses Grey relational analysis to find out which factor is most needed by customers and forecast needs extra production among series of product design proposal. The prediction results assisted designer to choose the best alternative from single product proposals and serialized proposals.
Sliding friction is utilized in the vehicular friction clutch to provide some slippage for smooth shifting and standing-start which is associated with some undesired issues, such as wear and heating of plates, introduction of high non-linearity and significant frictional dissipation. In order to reduce heat generation and frictional dissipation during slipping phase, a novel concept of clutched train is proposed to substitute for friction clutch. The dynamics of clutched train is modeling and integrated into powertrain to estimate the effects of clutched train on longitudinal vehicle oscillations stimulated by the sudden change of accelerator pedal. Further, the engagement control of clutched train can be transplanted from the developed control algorithm of friction clutch due to their similar control-oriented models, and the influence on longitudinal vehicle oscillations aroused by clutched train engagement is investigated. Simulation results show that it can behave like the conventional clutch and satisfy the requirement of driving comfort with certain control algorithm. Finally, the frictional dissipation of clutched train engagement is evaluated and compared with friction clutch engagement.