The user innovation community does not consider the impact of incentive mechanism of enterprise on the knowledge sharing behavior of lead users. In order to solve the problem, a new knowledge sharing behavior incentive mechanism for lead users based on evolutionary game was proposed. Firstly, the enterprise and lead users were regarded as the main players of the evolutionary game, and the models under the conditions that the enterprise did not adopt incentive measures and the enterprise adopted incentive measures were constructed respectively. Then, to explore the dynamic evolution process and evolutionary stable strategy of the system, the local stability analysis was performed to the two models respectively. Finally, through the computer simulation, the evolution results of knowledge sharing under the two conditions were compared, and the influence factors and the best incentive strategy of the knowledge sharing behavior of lead users were analyzed. Experimental results show that, the enterprise taking incentive measures can effectively promote the knowledge sharing behavior of lead users, and when the incentive distribution coefficient is controlled within a certain range, the system will reach the best stable state; the optimal incentive distribution coefficient is determined by knowledge sharing cost, knowledge search cost and additional cost; the knowledge sharing cost, knowledge search cost and incentive distribution coefficient can significantly influence the level of knowledge sharing behavior of lead users.

Aiming at the problem of high time complexity of Conditional Preference networks (CP-nets) graph model in reasoning computation, a Generating CP-nets with Bounded Tree Width based on Dandelion code (BTW-CP-nets Gen) algorithm was proposed. First, through the principle of bidirectional mapping between Dandelion code and tree structure with tree width k ( k-tree), the decoding and encoding algorithms between Dandelion code and k-tree were derived to realize the one-to-one mapping between code and tree structure. Second, the k-tree was used to constrain the tree width of CP-nets structure, and the k-tree feature tree was used to obtain the directed acyclic graph structure of CP-nets. Finally, the bijection of discrete multi-valued functions was used to calculate the conditional preference table of each CP-nets node, and the dominant query test was executed to the generated bounded tree-width CP-nets. Theoretical analysis and experimental data show that, compared with the Pruffer code generating k-tree (Pruffer code) algorithm, BTW-CP-nets Gen algorithm has the running time on generating simple and complex structures reduced by 21.1% and 30.5% respectively,and the node traversal ratio of the graph model generated by BTW-CP-nets Gen in the dominant query is 18.48% and 29.03% higher on simple structure and complex structure respectively; the smaller the time consumed by BTW-CP-nets Gen algorithm, the higher the traversal node ratio of the dominant query. It can be seen that BTW-CP-nets Gen algorithm can effectively improve the algorithm efficiency in graph model reasoning.

In the process of traditional impact assessment of engineering change propagation for complex products,the joint effect of different association relationships among parts on change propagation is not comprehensively considered. Therefore,the multiplex network theory was applied to the modeling of complex product. Firstly,to explore the impact of different association relationships on engineering change propagation,the parts of a complex product and their functional, behavioral and structural association relationships were abstracted to a multiplex network. Then,the improved all-around distance index was used for evaluating the importance degrees of nodes in the multiplex network. Finally,the Susceptibility-Infection-Susceptibility(SIS)model was used to quantitatively assess the impact of engineering change propagation. To verify the effectiveness of the proposed method,the impact assessment of engineering change propagation of a type of diesel engine was taken as an example. Results demonstrate that:the multiplex network can fully describe complex products with different types of association relationships;the improved all-around distance index increases the ability to distinguish the importance degrees of nodes with the same coreness;the change in high-important parts will cause the avalanche propagation of engineering change throughout the product range.

In Ciphertext-Policy Attribute-Based Encryption (CP-ABE) schemes, the private key is defined on attributes shared by multiple users. For any private key that can not be traced back to the owner of the original key, the malicious users may sell their decryption privileges to the third parties for economic benefit and will not be discoverable. In addition, most of the existing ABE schemes have a linear increase in decryption cost and ciphertext size with the complexity of access structure. These problems severely limit the applications of CP-ABE. By defining a traceable table to trace the users who intentionally disclosed the key, the cost of the decryption operation was reduced through the outsourcing operation, and a CP-ABE scheme with traceable and fully verifiable outsourced decryption was proposed. The scheme can simultaneously check the correctness for transformed ciphertexts of authorized users and unauthorized users, and supports any monotonous access structure, which traceability will not have any impact on its security. Finally, the proposed scheme is proved to be CPA (Chosen Plaintext Attack)-secure in the standard model.

The malicious cloud server may send incorrect or forged query results to the user, and the authorized user may send the key information privately to a non-authorized user after completing the retrieval. In order to solve the problems, a new verifiable ciphertext retrieval scheme with user revocation was constructed. Firstly, an encryption algorithm was used to encrypt the user documents and sign the keywords. Secondly, a searching algorithm was used to retrieve documents that needed to be retrieved. Finally, a verification algorithm and user revocation algorithm were used to verify the retrieval results and encrypt the unretrieved documents again. The analysis results show that, the proposed scheme can complete the accurate retrieval on the premise of guaranteeing the integrity of data, realize the user revocation through re-encryption scheme, and guarantee the security of system. Moreover, the proposed scheme satisfies the security of Indistinguishability-Chosen Keyword Attack (IND-CKA).

The main problems exist in current Attribute-Based Encryption (ABE) schemes, such as the access policy has a single function, and the size and decryption time of ciphertext increase with the complexity of access formula. In order to solve the problems, a multi-function ABE scheme for effecient outsourced computing was proposed. Firstly, through the fine-grained access control of sensitive data, different function encryption systems were implemented. Then, using the huge computing power of cloud server to perform partial decryption calculations, the user attribute ciphertext satisfying the access policy was converted into a (constant-size) ElGamal-style ciphertext. At the same time, the correctness of outsourced computing was ensured through the efficient verification methods. The theoretical analysis results show that, compared with the traditional attribute-based functional encryption scheme, the decryption computation at the user end of the proposed scheme is reduced to one exponential operation and one pair operation. The proposed scheme can save a lot of bandwidth and decryption time for users without increasing the amount of transmission.

Combining with the privacy-preserving problem of secure outsourced computation in the cloud and aiming at arbitrary outsourcing multivariate polynomials, a publicly verifiable outsourced computation scheme based on two-server model was constructed by homomorphic encryption and multilinear mapping. The scheme can guarantee the privacy and security of inputs and outputs of polynomial functions, and reach the goal that users or any third party can verify the correctness of the results, thus achieving open verification and availability. The results returned by the cloud are in the state of encryption, only users who have decryption key can output the final results, which can ensure the security of computation. Besides, the scheme can achieve Chosen Plaintext Attack (CPA) security of inputs in the standard model, and the user's computational cost is much less than that of the server and direct computation.

The traditional key policy attribute base encryption and decryption scheme has the disadvantages that the ciphertext length increases linearly with the increase of the number of attributes, and consumes a large amount of communication bandwidth of the user in the communication process. The improved scheme of attribute encryption was proposed. Based on the encryption of key policy attributes, a verifiable packet decryption scheme with fixed ciphertext length was proposed. In the non-monotonic access structure, the cipher length was fixed, and the communication bandwidth was effectively saved. Through the improvement of outsourced key generation algorithm, a primary modular exponentiation operation was realized, and the generation time of key generation was effectively shortened.The hash function was used to realize the verification of the decryption and its security was proved.

Focusing on the issue that there exist defects of vertex data redundancy and lack of adjacency information among the faces in the STereo Lithography (STL) file format, an explicit algorithm of surface topology reconstruction was presented based on the multi-dimensional dynamic spatial index. During the process of eliminating the copies of the mesh vertex data, the K-Dimensional Tree (KD Tree) of the vertices on the mesh surface was gradually built. The efficiency of eliminating the vertex copies was improved by the index and the surface topology was rapidly built based on the storage openness of the data in the leaf node layer of KD-tree, in which the half-edge data structure could be integrated. Finally, compared with methods using R ^*-Tree, array and hash table as index, the proposed dynamic spatial index integrated KD-Tree with half-edge date structure used 11.93 s to remove redundant vertices and 2.87 s to reconstruct surface topology when dealing with the data file of nearly one million faces, which significantly reduced the time of eliminating the redundant vertices and surface topology reconstruction. And the index effectively supported quick query of the topology information of mesh surface with the query time in 1 ms, which was far less than the comparison algorithms. The experimental results show that the proposed algorithm can improve the efficiency of eliminating the vertex data redundancy and the topological reconstruction as well as achieve quick query of the topology information of mesh surface.

The matching points cant be decided absolutely by its residuals just relying on epipolar geometry residuals, which influences the selection of optimum inlier set. So a novel fundamental matrix calculation algorithm was proposed based on three-view constraint. Firstly, the initial fundamental matrices were estimated by traditional RANdom SAmple Consensus (RANSAC) method. Then matching points existed in every view were selected, and the epipolar lines of points not in the common view were calculated in fundamental matrix estimation. Distances between the points in common view and the intersection of its matching points epipolar lines were calculated. Under judgment based on the distances, a new optimum inlier set was obtained. Finally, the M-Estimators (ME) algorithm was used to calculate the fundamental matrices based on the new optimum inlier set. Through a mass of experiments in case of mismatching and noise, the results indicate that the algorithm can effectively reduce the influence of mismatch and noise on accurate calculation of fundamental matrices. It gets better accuracy than traditional robust algorithms by limiting distance between point and epipolar line to about 0.3 pixels, in addition, an improvement in stability. So, it can be widely applied to fields such as 3D reconstruction based on image sequence and photogrammetry.

Faced with the inefficiency problem of current identity-based multi-signcryption schemes, an efficient and secure identity-based multi-signcryption scheme was proposed. The new scheme eliminated the number of multiplicative operations, and increased the procedure of key verification. Furthermore, through security and efficiency analysis in the standard model, the new scheme is proved secure under computational Diffie-Hellman assumption and reduces the calculation work. Compared with the known schemes, the new scheme is more secure and efficient.