An XML-based approach to represent generic bill of materials

To solve the difficulty in describing the generic bill of material (GBOM) with the conventional tabular structure in a relational database system,a novel XML-based approach is presented to represent GBOM. It can represent and maintain one generic structure that encompasses all variants of a product. With the combination of product-oriented notation,this approach further gives a high degree of flexibility to support the user in the product variant specification task. The generic BOM system is then introduced for the particular product variant,and a prototype system has been developed. It is indicated that the presented approach is feasible.     

基于有效交叉点搜索的点串等距边界环生成算法

提出了一种根据零件截面点串边界曲线生成等距加工轨迹的新算法。当点串边界曲线的等距环自交或内外环相交时,根据边界上交叉点的穿越深度判定出有效交叉点,在有效交点处的四段进出边中选取一对转角最大的进边与出边连入环中,形成环形加工轨迹。该算法已在自主开发的RPM数据处理软件中成功应用。该算法提高了已有数据处理软件的稳定性;并在此基础上实现了RPM的OFFSET加工轨迹的生成。     

用混合像元线性模型提取中等植被覆盖区的粘土蚀变信息

基于混合像元线性分解模型,针对中等植被覆盖区提出了一种提取粘土蚀变信息的新方法。主要分3步实现:用混合像元线性分解模型提取植被覆盖丰度;对线性模型进行完善,并依此重构不含有植被信息的新的多波段图像;利用TM5/TM7增强粘土蚀变信息。经验证,提取的植被信息以及粘土类蚀变信息与实际吻合较好,与基于比值-主成分分析的方法相比有明显的优越性。
     

A process net model approach for multiple process plans

A process planning system that generates alternative process plans offers multiple process plans for a part, thereby providing the flexibility to cope with changes in shop floor status. In this paper, we introduce the concept of a process net as a model for the generation of alternative process plans. We also show the usefulness of the process net model in generating alternative process plans by implementing the developed system to construct process nets, and devising an algorithm to generate alternative process plans for rotational parts.     

Hybrid approach to distribution planning reflecting a stochastic supply chain

Today’s business environment is experiencing as a period of expansion and the globalization. Therefore, a distribution plan with low cost and high customer satisfaction in supply chain management (SCM) has been widely investigated. The purpose of this study is to establish optimal distribution planning in the supply chain. In this paper, a hybrid approach involving a genetic algorithm (GA) and simulation is presented to solve this problem. The GA is employed in order to quickly generate feasible distribution sequences. Considering uncertain factors such as queuing, breakdowns and repairing time in the supply chain, the simulation is used to minimize completion time for the distribution plan. The computational results for an example of a simple supply chain are given and discussed to validate the proposed approach. We obtained a more realistic distribution plan with optimal completion time by performing the iterative hybrid GA simulation procedure which reflects the stochastic nature of supply chains.     

Characteristics of turbine spacing in a wind farm using an optimal design process

The characteristics of turbine spacing for optimal wind farm efficiency were investigated using combined numerical models. The effects of wakes from upstream turbines were predicted by a model capable of determining velocity distributions on a rotor plane, based on Ainslie's approach. The performance results of a wind farm showed good agreement with measurements. The blade element momentum theory, in combination with a dynamic wake model, was applied. Wake model used the results of aerodynamic analysis as input properties. The optimal distance between wind turbines was predicted using a genetic algorithm to maximize efficiency in a wind farm. The results showed that the spacing between the first and the second turbines had the importance to the entire farm's efficiency.     

Interference-free tool path generation in five-axis machining of a marine propeller

The manufacture of a marine propeller typically requires long lead-time to generate five-axis tool paths. It usually takes several days to generate satisfactory tool paths with a general purpose CAD/CAM system. This paper proposes a novel methodology that generates effective five-axis tool paths for marine propellers. The machining of a propeller is accomplished in three steps: rough cut, semi-finish cut, and finish cut. For generating accurate finish cut tool paths, the proposed system computes check vectors that determine a maximum range of valid tool motion based upon tool size and passage width for each CL (Cutter Location) point along the tool path. Interference-free tool paths can be acquired by positioning the tool inside the two check vectors. The modelling capability for propellers is also of importance because it determines the eventual success or failure of the whole process. An iterative B-spline surface modelling technique is employed to improve the accuracy of the models and to increase the productivity. The proposed system generates interference-free tool paths with superior surface finish and reduces lead-time to manufacture a propeller. The system validation and sample results are given and discussed.     

机械产品图档文件管理系统

介绍一个能与产品ＣＡＤ／ＣＡＰＰ系统集成的通用的机械产品图档文件管理系统的组成、功能及设计原理。     

Investigation on minimum quantity lubricant-MQL grinding of 100Cr6 hardened steel using different abrasive and coolant–lubricant types

Large quantities of coolant–lubricants are still widely used in the metal working industry, generating high consumption and discard costs and impacting the environment. Alternatives to current practices are getting more serious consideration in response to environmental and operational cost pressures. In the grinding process, promising alternatives to conventional dry and fluid coolant applications are minimum quantity lubrication (MQL) or near dry grinding process. Despite several researches, there have been a few investigations about the influence of different types of coolant–lubricants and grinding wheels on the process results. The current study aims to show the effects of the above parameters on grinding performance such as grinding forces and surface quality. The tests have been performed in presence of fluid, air jet and eleven types of coolant–lubricants, as well as, in dry condition. The grinding wheels employed in this study were vitrified bond corundum, resin bond corundum and vitrified bond SG wheels. The results indicate that SG wheels and MQL oils have potential for the development of the MQL process in comparison to vitrified and resin bond corundums and water miscible oils. Also, the lowest thermal damages, material side flow on the ground surface and wheel loading were generated by using the SG grinding wheel in MQL grinding process.     

Contour pocketing computation using mathematical morphology

Tool path generation problem is one of the most complexes in computer aided manufacturing (CAM). Although some efficient algorithms have been developed to solve it, their technological dependency makes them efficient in only a limited number of cases. In the article we propose a model that will set apart the geometrical issues involved in the manufacturing process from the purely technology-dependent physical issues by means of a topological system. Presented in the paper there is a method for offsetting any kind of curve regardless of the machining technology (i.e., independent of any tool geometry: spherical, conical, toroidal and so on). Specifically, we use parametric cubic curves, which is one of the most general and popular models in CAD/CAM applications.