Applied Mechanics and Materials Vols. 548-549

Abstract: The high-performance parallel computing (HPPC) has a better overall performance and higher productivity, for a generical large-scale army equipment system of systems (AESoS) simulation, and the runtime efficiency can be multiplied several tenfold to several hundredfold. The requirement analysis of simulation framework of AESoS based on HPPC was proposed. After the simulation framework of AESoS based on HPPC and its key techniques were discussed, the simulation framework of AESoS Based HPPC was designed. it is of great significance to offer certain references for the engineering application in the simulation fields of AESoS based on HPPC.

Abstract: Nowadays, software is expected to have an extended lifespan, which makes the evaluation of its complexity at the early stages critical in upcoming maintenance. Indeed, complexity is proportional to the evolution of software. Software metrics were introduced as tools that allow us to obtain an objective measurement of the complexity of software. Hence, enabling software engineering to assess and manage software complexity. Reducing software costs is one of the major concerns of software engineering which creates an increasing need for new methodologies and techniques to control those costs. Software complexity metrics can help us to do so. In this paper, we would investigate how those metrics can be used to reduce software costs. We would first analyze the most popular complexity metrics and distinguish their properties. Then, we will show how each of those metrics fit within the software life cycle. Finally, we will provide a detailed approach to use the complexity metrics to reduce software costs.

Abstract: Against to the unsustainable problems of health diagnosis, fault location and fault tolerance mechanisms that existing in the current avionics applications, we proposed a fault-tolerant communication middleware which is based on time-triggered in this paper. This middleware is designed to provide a support platform for applications of the real-time based on communication middleware. From the communication middleware level and also combined with time-triggered mechanism and fault-tolerant strategy, it diagnoses the general faults first, and then routes them to the appropriate fault mechanism to process it. So the middleware completely separates fault-tolerant process from the application software functions.

Abstract: Network crawler as web information extraction tools, it can download web pages from internet for the engine. The implementation strategy and operating efficiency of crawling program have a direct influence on results of subsequent work. The paper aimed at the shortcomings of ordinary crawler, puts forward a practical and efficient precise crawler theme method for the BBS, the method for the BBS characteristics, attempts in the web page parsing, theme correlation analysis and the crawling strategy, using the template configuration, analyze and crawl on the article. The method is better than the general crawler in the performance, accuracy and comprehensive rate.

Abstract: This paper presents a quickly locate the query methods in the face of huge amounts of data. The method by analyzing the data relationship, split the database, the formation of cross-database quickly Hash positioning table, and by analyzing the query cost to build double weighted graph and weight table. Each query is given based on the node weight table fast cross-database query path, and quickly locate the target from the cross-database positioning Hash table Hash calculation, in order to achieve fast positioning method.

Abstract: The composition, related knowledge and implementation of Bluetooth roll call system based on Android platform were introduced in this paper. The Bluetooth roll call system designed was simple, convenient, effective and reliable; its data transmission was stable, and suitable for teachers’ daily teaching.

Abstract: Private signature is a signature which provides signature privacy and restricted transference. Using the private scheme a user can sign a message in such a way that only a designated verifier can verify the signature. In some cases, the signer may want to preserve the privacy forever, which means that the initial verifier should not be able to convince anyone else of the fact that the signer signed the message. In some other cases, the signer may want to give the initial verifier the possibility to transfer his conviction to someone else, if desired. In this paper we first review the private signatures proposed by Javier Herranz, and point its drawback. Then we propose efficient private signature by combining a secure signature scheme and a non-interactive one-way key agreement.

Abstract: Currently, When Shielding effectiveness(SE) test was conducted in MIL-STD-188-125-1, The experiments are using Loop antenna, Log Periodic(LP) antenna, Biconical antenna about shielding in the frequency range of 10k∼1GHz. But, Their size in the shielding effectiveness test influences chamber construction costs. And these influences play a role in increased production costs. So spiral antenna to clear antenna size problem was proposed. This antenna has small size and function to cover broad frequency compared to other antennas. To evaluate antenna performance, we use commercial software simulation program. And we observe radiation characteristic changing arm width and distance between arm. First, through magnitude analysis of S-parameter, antenna characteristic according to each arm distance is analyzed. Secondly, through Theta/Degree Vs. dB function and 2D/3D model, radiation pattern of antenna is investigated. Third, radiation energy magnitude and characteristic of antenna is investigated in simulation program.

Abstract: Spectrum sensing is used to identify the unused frequency bands and as such plays a key role in dynamic spectrum access. In most of the existing spectrum sensing models, the channel state of primary user is assumed unchanged within the spectrum sensing duration, which is not suitable for the channels with high activity, in which the primary user accesses or vacates from the channel frequently. In this paper, a Modified Energy Detection (MED) algorithm is proposed for this scenarios by considering the primary user activity within the spectrum sensing duration. Theory analysis and computer simulation results show that both the probability of detection and false alarm in this scenarios have been improved with our MED.

Abstract: Using multiple antennas in coexisting radio systems can cancel or control the co-channel interference and hence improves the overall spectrum efficiency. However, the hardware complexity and costs limit the usage of multiple-antenna technology. Antenna selection may reduce such costs while partly remaining the advantage of the multiple-antenna technology. In this paper, a fixed power cognitive radio system model jointly combined with antenna selection and users selection is set up. And the mathematical closed-form expressions of the channel capacity and bit error rate (BER) are obtained through mathematical derivation. Simulation verifies the correctness of theoretical results and shows that the system exists an optimal transmit power which optimizes the system performance. Furthermore, the influences of users number and antennas number on the system performance have been studied.