常见涂料的主要特性和我国涂料产业面临的机遇

涂料是一类使用非常广泛的化工产品，随着我国经济的快速发展，我国的各个行业对于涂料的需求也迅速增长。但是，目前我国涂料的高档次产品还非常欠缺。本文从材料本性方面对于各种涂料进行了介绍，并且提出应当抓住机遇迅速提升我国高性能涂料的研究开发和生产，使整个行业水平得以提升。     

Solid-state interfacial reactions and compound morphology of cBN grain and surface Ti coating

In order to research thoroughly the mechanism of the solid-state interfacial reactions and the induced compound morphology of cubic boron nitride (cBN) abrasive grains and the surface Ti-coating layer, annealing experiments of Ti-coated cBN grains were conducted at different temperatures of 550-950 °C for dwell times of 60 min under high-vacuum conditions. The corresponding interfacial characteristics were investigated by differential thermal analysis, X-ray diffraction and scanning electron microscopy. The results show that the relevant interfacial reactions and compound morphology between cBN and Ti are significantly influenced by the heat-treatment temperature. No reaction occurs below 550 °C, and TiN is the sole reaction product during heating from 650-750 °C. Three kinds of compounds, TiN, TiB₂ and TiB, can exist in the interfacial region at 950 °C. Here, the favorable interfacial structures, cBN/TiB₂/TiB/(TiB+TiN)/TiN/Ti, are developed for the excellent mechanical and chemical transition effects between cBN grains and Ti coating. The thermodynamic analysis finally predicts that there is a reasonable probability for the formation of such a special interfacial transition layer.     

深处的激情

在澳大利亚一片森林的深处，当弯曲钢架结构的假日别墅内泛起火光的时候，它确实将世界照亮了，《Wallpaper》总第83期讲述一段深处的激情。[编者按]     

毛泽东的社会主义发展阶段思想与社会主义初级阶段理论

毛泽东在领导中国人民探索建设社会主义的过程中，对社会主义发展阶段问题进行了深入的思考，提出了许多重要的思想。这些宝贵的思想成为我们党形成社会主义初级阶段理论的思想来源之一。探讨毛泽东与社会主义初级阶段理论的关系，有助于我们加深理解毛泽东思想及其和邓小平理论之间的渊源关系。     

Voice capacity analysis of WLAN with unbalanced traffic

An analytical model to study the performance of wireless local area networks (WLANs) supporting asymmetric nonpersistent traffic using the IEEE 802.11 distributed coordination function mode for medium access control (MAC) is developed. Given the parameters of the MAC protocol and voice codecs, the voice capacity of an infrastructure-based WLAN, in terms of the maximum number of voice connections that can be supported with satisfactory user-perceived quality, is obtained. In addition, voice capacity analysis reveals how the overheads from different layers, codec rate, and voice packetization interval affect voice traffic performance in WLANs, which provides an important guideline for network planning and management. The analytical results can be used for effective call admission control to guarantee the quality of voice connections. Extensive simulations have been performed to validate the analytical results.     

Combined and iterative form of spatial and temporal error concealment for video signals

Video transmission over unreliable channels may suffer from the data loss or corruption. To facilitate the transmission, video content is compressed to save the bandwidth. The compression algorithms remove the redundancies in the video signal, meanwhile increasing the dependencies among symbols in the compressed bit-stream. Thus, when errors occur, they may propagate in both space and time. Among various error control techniques, error concealment (EC) is an effective method that is performed at the decoder to mitigate the influence of errors on the quality of reconstructed images. In this paper, a joint spatial and temporal EC algorithm (JSTEC) is presented. First, several existing temporal EC algorithms are combined in an appropriate order. Then, the spatial correlation in the video is exploited in an iterative form to improve the performance of the temporal EC. Experimental results show that JSTEC performs better both in peak signal-to-noise ratio and subjective quality of images than the existing algorithms.     

A novel frequency offset estimation method for OFDM systems with large estimation range

In this paper, we proposed a novel frequency synchronization method which has larger estimation range than conventional method proposed by Tufvesson. A two steps frequency offset estimation method is performed in the new method. In the first step the received signal is correlated with local training sequence to eliminate the influence of training sequence which makes the estimation range of frequency offset is independent of period of the repeated data in the training sequence. The received signal is correlated with its delay in the second step to obtain the fine estimation of frequency offset. Precise estimation can be achieved in the proposed method than Tufvesson's method. The period of the repeated data in the training sequence determines the estimation range of the frequency offset in the conventional method, while in the new method they are irrelevant. Tens of subcarriers spacing can be estimated by the new method. The new method can be used in other cases as long as a known sequence is transmitted, which will introduce valuable flexibility in training sequence design. The validity of the algorithm is verified in AWGN channel and multipath fading channel.     

手机发送WAP邮件

介绍了基于ASP WML,利用JMail组件实现手机发送WAP邮件的功能,解决了中文邮件内容传递中的乱码问题并提供了具体实现代码及测试办法.     

采用FPGA通过BT.656接口实现传输4路视频流的方法

提出一种使用FPGA(现场可编程门阵列)实现一个ITU-R BT.656并行硬件接口传输4路CIF格式视频流的方法。该方法说明了从视频处理器到FPGA传输4路CIF格式视频流的数据结构,利用该数据结构,一个ITU-R BT.656的硬件接口可传输4路不同的CIF格式的视频数据流。FP-GA将4路视频数据流分离、插值生成D1(720×576像素)格式的数据输出给视频处理器。这种方法提高了视频处理器的扩展性,增加了视频处理器输出视频的路数。