摘要：The paper presents a wideband high frequency (HF) channel simulator. The simulation consists of a software simulation of a direct-sequence spread-spectrum (DSSS) HF system with RAKE receiver. The validity of the HF channel simulator is demonstrated by the analysis of the scattering function and example results of the simulator. The performance of DS system under HF channel and noise are also presented. The simulation results and theoretical analysis show that a straightforward DS system may properly mitigate the intersymbol interference (ISI) distortion of the HF channel while perform badly under the HF noise and interference.

摘要：Web offers a very convenient way to access remote information resources, an important measurement of evaluating Web services quality is how long it takes to search and get information. By caching the Web server’s dynamic content, it can avoid repeated queries for database and reduce the access frequency of original resources, thus to improve the speed of server’s response. This paper describes the concept, advantages, principles and concrete realization procedure of a dynamic content cache module for Web server. Key words dynamic content caching - network acceleration - apache module CLC number TP 393.09 Foundation item: Supported by the Science Committee of WuhanBiography: LIU Dan (1980-), male, Master candidate, research direction: high speed computer network, high performance server clusters system.

摘要：This paper describes a new interleaver construction technique for turbo code. The technique searches as much as possible pseudo-random interleaving patterns under a certain condition using genetic algorithms(GAs). The new interleavers have the superiority of the S-random interleavers and this interleaver construction technique can reduce the time taken to generate pseudo-random interleaving patterns under a certain condition. The results obtained indicate that the new interleavers yield an equal to or better performance than the S-random interleavers. Compared to the S-random interleaver, this design requires a lower level of computational complexity. Key words interleaver - Turbo codes - genetic algorithm CLC number TN 911. 22 Foundation item: Supported by the National Natural Science Foundation of China (60372057) and the Key Open Laboratory on Information Science and Engineering of Railway Transportation Ministry of Beijing Jiaotong University of China (KLISAE-0103)Biography: Tan Ying (1963-), female, Associate professor, Ph. D, research direction: error control coding, analysis and design of wireless communication system.

摘要：This paper, using the frequency bandwidth, where both the gain and the VSWR (Voltage Standing Wave Ratio) of a monopole can satisfy the design requirement, as object function, mainly describes the process, in which the load locations, the matching network topology and their component values are optimized by the AGA (Adaptive Genetic Algorithm), to achieve a gain more than -2 dB in horizontal direction and a VSWR less than 3 in bandwidth as wide as possible. Moreover the design results are presented for monopoles with two concentrated loadings. It shows that the AGA is an effective method for designing wideband antennas.