Applied Mechanics and Materials Vols. 143-144

Abstract: All aspects of coal mining will emit large quantities of dust to the tunnel. There are many factors of the floating dust in the tunnel affecting the propagation of electromagnetic waves, such as frequency, consistency and droplet. Combining with the formula in relevant references, this paper uses software to simulate and obtains relevant characteristic curves. Finally, it is clear that the attenuation of propagation increases with the frequency of electromagnetic waves, dust consistency, droplet and temperature also affect the propagation characteristic. Obviously, these factors almost weaken the propagation of electromagnetic waves

Abstract: With the extensive application of wireless sensor networks, low energy consumption of nodes is the most important consideration.The medium access control MAC protocol is an important technology that structures first floor foundation network architecture. In this article by comparing the domestic and foreign research results, current several kinds of quite typical MAC protocol is analyzed according to the energy saved aspect. According to the special environment of coal mine, we got a MAC protocol which was suitable to mine.

Abstract: The RFID technology of personnel orientation in coal mine is introduced in this article. Combined with special circumstances and special coal mine safety regulations, the unavoidable collision problem in RFID is also analyzed detailedly. It points out the deficiencies of the general anti-collision algorithm. Then it brings forward an improved anti-collision algorithm, which is significative for enhancing performance of personnel orientation system in coal mine.

Abstract: The application solution of OFDM-Based Transform Domain Communication System (TDCS) in mine is proposed under the ground where wireless communication is easily disturbed in mine environment. In this paper ,concept, characters and system constitutes of Transform Domain Communication System are introduced. The design and simulation methods are discribed in detail in this thesis. According to the analysis, this solution has good resistance to multipath fading, interference and noise characteristics and wireless communication is more effective in that complex electromagnetic field environment

Abstract: Analyzed and recomposed to J2EE architecture, and during research of design pattern, the document bases on existing frame for achieving more application-layer reuse to engineer framework, and forms an optimal design pattern of electronic commerce. The pattern is actualized in on-line shopping system found on J2EE. The experiment results show that it reduces system development cycle, optimizes system structure, enhances the system's performance, and decreases the risk and the cost in software development when the framework and design pattern are combined artfully to use on electronic commerce

Abstract: A fast automatic routing method based on skeleton model in virtual environment is introduced in this paper. By defining the properties of the stent, electronic connector and electronic equipment of the routing solid model, the routing factors are obtained and skeleton is built. Then, the cables can generated automatically based on the connection relationship and cable attributes. This method can bring out the connection between electronic connector node tables and 3D model, managing the network path, flexible modification of 3D routing features, 3D routing automatically, and generating cable branch diagrams. The routing efficiency can be improved and the length of the cables inosculates with the actual one perfectly, which is of great value in engineering.

Abstract: Security of authentication protocol is an important factor to network security. To ensure protocol security, attacks on authentication protocol were classified from the aspect of security theory and implement. On this basis, an authentication protocol security assessment was discussed. The framework determines security risk of authentication from security of password system, vulnerability of protocol itself and environment threat possibility. It can be used to assess security and capability to resist risks objectively

Abstract: The efficiency of metadata indexing is important to the performance of distributed file system. Time and space spending of current metadata management algorithms are unstable. In this paper, we use B-tree to index the metadata of distributed file system. Lustre is an open source distributed file system in which Hash function is used to manage the metadata. We implement the prototype of metadata indexing sub-system on Lustre and use Iozone to test the I/O performance of Lustre with and without the metadata indexing sub-system respectively. The simulation results show that Lustre with the metadata indexing sub-system has higher adaptability than Lustre with Hash-based metadata management algorithm.

Abstract: As a problem of network flows, pipe network layout optimization is a combinatorial problem with variable weight. This paper takes flow variation by different layout scheme into account to the pipeline optimization and obtains the irrigation pipe network layout optimization with variable weight. Line-up competition algorithm (LCA) is introduced to optimize the tree pipe network layout. The corresponding fitness function, encoded mode and mutation are designed on the basis of the characteristic of tree graph expressed by adjacency matrix. It is testified by case study that LCA can obtain the optimal result, and is better in search efficiency and much stable compared with other algorithms.

Abstract: According to the characteristics of ZPMC automated container terminal operation system, this paper investigates the equipment distribution problem among transportation system, and establishes the scheduling solution of mathematical model for single ship with the shortest total loading/unloading time. Using an improved particle swarm algorithm as the experimental solving method, results show that the proposed model and algorithm are effective and practical.