The paper’s focus is on the module division dynamically in the virtual assembly sequencing process for the product family, which will affect the module variant quality seriously. Most research merely divides the module on their functions, without paying the attention on which the module division is beneficial for the latter assembly process. Considered assembly relationships as a key constraint, a new variant module division measure based on Extension Logic is presented. Since the tolerances existing everywhere in the assembly process, the connection analysis is employed to build a constraint function on the tolerance. Physical constraints contain mating and combination constraints. After the dynamical position for different parts, the mating constraint is defined as the movement opposition between two mechanical elements including face alignment mating, shaft and hole mating or face against mating. Then the extension radiation model could be generated. According the average value of the relationship function to realize the module division, the product structure is divided into several sub-assemblies. As the main problem in virtual assembly is process collisions, a modified integer coded Particle Swarm Optimization Algorithm is used. Here every part is mapped to corresponding particle. The result is performed in the virtual environment of software DELMIA. At last the extension cluster method in this paper is compared with the direct dynamic cluster method. A case study is performed on virtual assembly of high power Light Emitting Diodes automatic sorting machine manufactured by a factory.
To evaluate key clients comprehensively and objectively, a general comprehensive evaluation system of key clients is defined based on the analysis of the third party logistics enterprises. Then a formalized expression and basic element model of key client comprehensive evaluation problem is given. Furthermore, a key client comprehensive evaluation approach based on extension theory is presented. It adopts the optimal degree evaluation approach from the extension theory, which extends cantor set theory and fuzzy set theory in the semantics.The extension theory based comprehensive evaluation approach consists of three main steps. Firstly we need to determine the measuring weights using the AHP method; Secondly, we need to establish the dependent function, and calculate the qualification degree of each client using this formula, also we should normalize it. Thirdly, we calculate the optimal degree to evaluate the clients. The client with the highest optimal degree is the most important client for enterprise.This approach is implemented as computer program and integrated into the third party logistics intelligent information platform. Results show that the key client comprehensive evaluation approach is effective and efficient.
For the better and stronger information retrieval function, the sequence of search result queue and the correlation of query expression are the key problems that could be computed by similarity algorithm. A new method which is ontology-based weighted semantic tree similarity algorithm (OWSTS) is presented here. In this paper, the construction method of OWSTS and the implementation of similarity algorithm are introduced firstly. And an ontology-based information retrieval prototype system of mechanical products domain is developed secondly. Finally the relative accuracy of retrieval results by OWSTS and generally used cosine vector space based similarity algorithm (TF*IDF) are compared. The successful running of this system shows that OWSTS algorithm is feasible for information retrieval and the similarity algorithm makes the sequence of search result queue fit for users' semantic requirement.Index Terms -Mechanical product, domain ontology, weighted semantic tree, similarity algorithm, intelligent retrieval.
The development of aeroengine needs the collaboration of many enterprises. In order to realize the share and optimization configuration of different enterprises design and manufacturing resources, a method of realizing product collaborative development based on grid service is proposed. In the method, the collaboration among enterprises is realized by grid service cell. The grid service cell is an encapsulated service agent which can provide certain design and manufacturing abilities through the network. Enterprises can release their grid service information in the portal and create their grid service cells, and then they become the grid service supplier. The customers use the grid service matching engine to search the suited grid services in the portal and use these services to accomplish the product development. Accordingly the method can realize the optimization configuration of different enterprises design and manufacturing resources. Therefore, a prototype system of networked collaborative development of aeroengine based on grid service is developed. In the system, an ontology of aeroengine networked collaborative development is proposed, and the models of grid service cell and grid service requirement are built. Aiming at the matching of the grid service, a matching method based on semantic is proposed; a mathematic model for grid service matching is created and the corresponding matching algorithm is presented. Finally, we validated the prototype system with the example of the collaborative development of an aeroengine part.
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