Applied Mechanics and Materials Vols. 668-669

Abstract: In the atmospheric turbulence, the effects of atmospheric turbulence and transmitted optical power on the BER performance of ultraviolet communication system are analyzed and simulated. The simulation results show that when the atmospheric turbulence strength changes from weak to strong, the BER performance deteriorates along. Compared to OOK intensity modulation, the BPSK subcarrier intensity modulation can be more effectively to inhibit atmospheric turbulence effect on ultraviolet communication system. Under the certain atmospheric turbulence strength, the BER performance of ultraviolet communication system will be improved along with the increase of the transmitted optical power.

Abstract: IP traceback can be used to confirm locations of attackers, stop on-going attacks, and take legal actions against attackers, and then impede attackers. This paper describes the background where IP traceback problem generates, and presents what the functions of IP traceback are. Furthermore, this paper classifies existing IP traceback methods and analyzes advantages and disadvantages of each method. In addition, future researches on IP traceback are proposed. This paper is of valuable reference for network researchers and engineers to be engaged in the further study on IP traceback.

Abstract: A CAD software system for hull lines based on .NET is introduced in terms of system construction and principle. The system adopts a 3D V-shaped fairing computing model, which sufficiently considers the consistency of lines offsets in three different projection planes. By means of tree structure for parametric hull lines and 3-dimensional modeling technology, the system supports total-process-design of hull lines. Such a system not only can draw main parameter table, lines offsets table and lines plan grid automatically, support interactive design and synchronous adjustment for hull lines, but also can cut the hull synchronously and produce the 3-dimensional model of the hull. The implementation of this CAD software system for hull lines improves the hull design efficiency and quality.

Abstract: Multi-user detection is one of the key technologies of CDMA systems. Its basic idea is that, all user signals are considered as useful signals. Then, we can use them to eliminate multiple access interference (MAI). This paper presents an improvement of multi-user detection based on QS-CDMA systems. By the improving, computational complexity is lower, and performances approach synchronous CDMA systems.

Abstract: SLC500 PLC can not directly communicate with the Profibus device, which limits its practical application. This paper studies the Profibus protocol and proposes a scheme to realize communication between SLC500 PLC and Profibus network through Flex I/O module, which is prepared for applying SLC500 PLC in multi-protocol environments. The proposed solution can improve the communication efficiency and the response speed in control systems. Experimental results have validated the proposed method’s accuracy, reliability and efficiency in data communication.

Abstract: In order to prolong the lifetime of WSNs, low-duty-cycled scheduling is a widely used strategy. However, there exists high latency with traditional routing algorithms. In this paper, we model the data collection scheme of WSNs to be a delay optimization problem and propose a distributed algorithm based on Network Utility Maximization. The proposed algorithm can distributed find an optimal routing to achieve minimal average end-to-end delay. The simulation results show that our algorithm performs better than the traditional shortest path algorithm on end-to-end delay with less control message.

Abstract: This paper mainly discusses the problem of localization algorithm for wireless sensor network. For improving the disadvantages of high positioning error and Low coverage, an improved algorithm is proposed based on the optimum node selection determined by the received RSSI strength and virtual anchor nodes. It uses anchor node to locate which selected within 0.5 communication scope of the node by RSSI signal strength. Nodes Completed positioning upgraded to virtual anchor nodes .Complete positioning upgraded to virtual anchor nodes to help neighbors to locate. It reduces the positioning error and improves the positioning accuracy. Simulation experiment shows that the positioning performance of improved algorithm is better than traditional Bounding Box algorithm.

Abstract: The live migration of virtual machine (VM) is an important technology of cloud computing. Down-time, total migration time and network traffic data are the key measures of performance. Through the analysis of dynamic memory state of a virtual machine migration process, we propose a dirty pages algorithm prediction based on pre-copy to avoid dirty pages re transmission. Experimental results show that, compared with the Xen virtual machine live migration method adopted, our method can at least reduce 15.1% of the total amount of data and 12.2% of the total migration time.

Abstract: In order to meet the rapid demand of the modern cryptographic communication, heterogeneous multi-core password system architecture is set up based on shared memory in Xilinx XUP Virtex-II Pro chip in this paper. Under this architecture, the encryption and decryption of the SMS4 algorithm is realized fastly. Make a contrast with the homogeneous multi-core password system and the heterogeneous one-core password system’s performance in the execution time, throughput and resource utilization of the SMS4 algorithm.The experimental results show that the heterogeneous multi-core password system which based on shared memory has better performance.

Abstract: ETL refers to the process of data extracting, transformation and loading and is deemed as a critical step in ensuring the quality, data specification and standardization of marine environmental data. Marine data, due to their complication, field diversity and huge volume, still remain decentralized, polyphyletic and isomerous with different semantics and hence far from being able to provide effective data sources for decision making. ETL enables the construction of marine environmental data warehouse in the form of cleaning, transformation, integration, loading and periodic updating of basic marine data warehouse. The paper presents a research on rules for cleaning, transformation and integration of marine data, based on which original ETL system of marine environmental data warehouse is so designed and developed. The system further guarantees data quality and correctness in analysis and decision-making based on marine environmental data in the future.