Applied Mechanics and Materials Vols. 644-650

Abstract: Let s and t be two points on the boundary of a simple polygon, how to compute the Euclidean shortest path between s and t which visits a sequence of segments given in the simple polygon is the problem to be discussed, especially, the situation of the adjacent segments intersect is the focus of our study. In this paper, we first analyze the degeneration applying rubber-band algorithm to solve the problem. Then based on rubber-band algorithm, we present an improved algorithm which can solve the degeneration by the method of crossing over two segments to deal with intersection and in our algorithm the adjacent segments order can be changed when they intersect. Particularly, we have implemented the algorithm and have applied a large of test data to test it. The experiments demonstrate that our algorithm is correct and efficient, and it has the same time complexity as the rubber-band algorithm.

Abstract: At present, digital multimedia files containing text, images, audio and video are four main formats. In the search for multimedia files, because dissemination of images, audio and video files on the Internet, is lack of uniform standards, the same content will be used to describe different keywords. And it contains the richer content, the larger the amount of file data, as thus the traditional theme keyword search technology cannot meet the needs of the way of images and audio and video files. Text search technology is the most mature and widely used. Content-based search engine of search technology is an important topic in the development of digital media files on Internet search.

Abstract: Roof pre-splitting roadway is a new technology in roof induced rock burst prevention and control of incline coal seam. With the purpose of increasing rock burst prevention and control effective, FLAC^3D numerical simulation software was used to analyze stress distribution characteristics and roof pre-splitting effect and the layout of the roof pre-splitting roadway parameters. The results showed that the roof pre-splitting roadway changed roof and floor stress distribution, the stress concentration degree is high in the zone of roof and floor around pre-splitting roadway and the two ribs of pre-splitting roadway, which made the roof strength weakened and easy to break, avoiding a large overhang in the process of mining and rock-burst; The roof pre-splitting roadway led to stress concentration in the range of 5 ~ 10 m, roof effective weakening range 12 m, so the distance of two roof pre-splitting roadway should be more than 20m. The research provided the reference basis for rock burst prevention by roof pre-splitting roadway in the incline coal seam group mining.

Abstract: Frequent closed itemsets play an important role in pruning redundant rules fast. A lot of algorithms for mining FCI by vertical data formats have been developed. Previous methods often consume more memory for storage Bit-Vectors and the time for computing the intersection among Bit-Vectors. In this paper, it uses Dynamic Binary Group for compress the database and generates DBG-lattice for mining FCI. Advantages of this method are fast computing the support and the intersection of two DBGs. Experimental results show the efficient of this method in both the mining time and memory usage.

Abstract: This paper presents an algorithm about key management including key generation and key recovery in cryptosystem based on fingerprint and fuzzy decision. Traditional key for the encryption and decryption is remembered by a trusted person, or stored in a safety location. The key may be lost or misused for the person’s self-ish desire. Sharing secret algorithm is used to prevent from misusing in a single management, and fuzzy vault scheme is used to avoid the disadvantage of numerical password. But the proposed method is not an easy combination of fuzzy vault and sharing secret. To keep from the collusion among some persons, a simple fuzzy decision is added in the proposed method. Security analysis and experimental results are given to show the proposed algorithm is feasible and safe for key management in cryptosystem.

Abstract: Considering the confidentiality and integrity of big data in cloud storage, a MapReduce-based AES parallelization scheme is designed by using MapReduce framework of the open source Hadoop in this paper. The scheme takes full advantage of MapReduce and modern cryptography technologies to parallelize AES encryption and decryption process, in the way of data decomposition, which speeds up the efficiency in the implementation of encryption and decryption. Meanwhile, mix plaintext, separate storage and other technical means are taken into account in this scheme to ensure the confidentiality and security of the key and the ciphertext. By analyzing the performance, it is proved that the time consumption of new scheme is significantly reduced comparing with the traditional method.

Abstract: With development of computer technology, massive information has brought huge challenge on the storage system reliability. A algorithm called HG(Heuristic greedy) algorithm is proposed to optimal calculation path, reduce XOR operation and computational complexity for data recovery, which applies CRS(Cauchy Reed-Solomon) code to cloud storage system HDFS and turns multiply operation of CRS coding to binary matrix multiplication operation.The performance analysis shows that it improves fault tolerance of cloud file system, storage space effectively and timeliness with reduction of additional storage overhead.

Abstract: In view of the current popular cloud storage access control, some security problems were still existed. To solve the problem which the cloud service provider can’t verify the user write permissions by the CP-ABE based cloud storage access control, in this paper a cloud storage access control method is proposed which is based on the encryption algorithm of the cipher-text (CP-ABE) and the attribute-based signature (ABS). This method not only achieves the cloud storage environment information privacy and integrity, but also supports inheritance authorization and scalability.

Abstract: Aiming at solving data integrity protection problems in the cloud , a remote data integrity verification scheme is proposed. Firstly, the data integrity verification is constructed based on homomorphic identification and data fragment structure. Secondly, by introducing random mask, the public verification is realized and by building index-hash table (IHT), the scheme can support dynamic verification. Finally, use the MapReduce for parallel computing, which reduces computation overhead side and storage overhead. The security and performance analyses show that our proposed scheme is secure and reliable.

Abstract: A distributed reactive power optimization algorithm is put forward based on cloud computing and improved NSGA-II (fast non-dominated sorting genetic algorithm) in this paper. It is designed to solve problem of multi-objective reactive power optimization with huge amounts of data in power grid, whose difficulties lie in local optimum and slow processing speed. First, NSGA-II's crossover and mutation operator are improved based on Cloud Model, so as to satisfy the adaptive characteristics. In this way, we improved global optimization ability and convergence speed when dealing with large-scale reactive power optimization. Second, we introduced cloud computing, parallelized the proposed algorithm based on MapReduce programming framework. In this way, we achieved distributed improved NSGA-II algorithm, effectively improved the calculation speed of handling massive high-dimensional reactive power optimization. Through theoretical study demonstrated the superiority of the algorithm to solve the Multi-Objective reactive power optimization.