Pdm System Security And The Document Management Key Technologies

The dissertation makes a presentation of the research and development of PDM (Production Data Management) system. We call it X-PDM in the following. X-PDM takes modern project management as its core, and aim at the trade of electronic products designing for army.The main topic of the thesis is talking about the security services of X-PDM, the realization of the security scheme, and the automatic understanding for electronic circuit schematic drawings, which is the key technology of document management in X-PDM. The characteristic, the system structure and system management module of X-PDM are also mentioned in the thesis.First in chapter one, we introduce the background of X-PDM system and the development of PDM technology. We propose the frame of the whole system and introduce the X-PDM system structure and the network that it runs on.In chapter 2, the basic algorithms and protocol of applied cryptography are introduced here, including symmetric-key cryptography, public-key cryptography, hash functions and key management protocols. The algorithms and protocols are the base of modern information security technology. Kinds of typical algorithms widely used are listed, such as DES, RSA and MD5, and we also discuss the security of them.In chapter 3, we describe the research and development of X-PDM security scheme. Distributed Multi-tiers Architecture is the way that PDM are focusing on. X-PDM is constructed on this architecture. Comparing with ISO7489-2, aiming at the hidden troubles of the distributed 3-tiers architecture, we redefine the security services of X-PDM into 4 classes, which are authentication, access control, data security and anti-repudiation. Based on user management, kinds of cryptography algorithms and protocols, an integrated and applied realization of security service is proposed. The principal parts of the scheme includeapplication server access authentication, database server access authentication, secure communication, and administrator attack prevention. The scheme is already realized in X-PDM. At last, we also introduce the main functions, module flow and relationship between interfaces of system management module.In the last chapter, the automatic understanding system for electronic circuit schematic drawings is introduced. It is a key part of X-PDM document management. The main task of it is to recognize 3 kinds of element inside the drawings, including characters, components and also the topologic of the whole graph. And finally, count out the kind and the number of each component symbols, and redraw the circuit schematic drawing. After characters are divided from the raster image, the features of characters are extracted by symmetrical grids and then are inputted into BP neural network for further analysis. For components, we use the means of feature extraction and also propose Structural Pattern Recognition to recognize them. After all 3 kinds of elements being recognized, they are well organized to form the final result.