共查询到20条相似文献,搜索用时 31 毫秒
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ZHANG Hong-wei 《上海交通大学学报(英文版)》2005,10(4):349-353
A new improved group space-time block code (G-STBC) based on constellation rotation for four transmit antennas was proposed. In comparison with the traditional G-STBC coding scheme, the proposed space-time code has longer code length and adopts proper rotation-based symbols, which can increase the minimum distance of space-time codes and thereby improve code gain and achieve full diversity performance. The simulation results verify that the proposed group space-time code can achieve better bit error performance than both the traditional group space-time code and other quasi-orthogonal space-time codes. Compared with Ma's full diversity full rate (FDFR) codes, the proposed space-time code also can achieve the same excellent error performance. Furthermore, the design of the new space-time code gives another new and simple method to construct space-time codes with full diversity and high rate in case that it is not easy to design the traditional FDFR space-time codes. 相似文献
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GUO Qiang 《上海交通大学学报(英文版)》2005,10(4):364-367
Mobility management is a very important function of mobile communication in all-IP radio heterogeneous network. In order to achieve an efficient mobility management, with low delay and low beacon overhead, a micromobile stream control transmission protocol (mmSCTP) scheme was proposed. This scheme reasonably utilizes SCTP features and elaborately designs execution-steps for vertical handoff. Moreover, it provides fast locating for idle mobile node when a session is initiated by the correspondent node. The analytical and simulation results show that the proposed scheme is effective in supporting fast vertical handoff and effective location management. 相似文献
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国内外对有关吸水性石料的研究和应用报道较少。规范JTJ032—94不允许石料吸水率>2%(玄武岩除外)用于高等级沥青路面,实践证明,通过技术改进吸水率稍大于2%的一般石料也能够较好地应用在局部路段的高等级沥青路面上,可以解决某些特殊地区由于石料吸水性偏大不能应用,导致建设成本大大提高的问题。 相似文献
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主动交通管理系统(ATM)是将经试验和检测的交通管理技术和现有技术,改进技术、新技术融合起来的交通管理系统,该系统正在英国伯明翰东南部的M42公路上试用。 相似文献
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作为公路承重基础的公路路基,其施工的质量直接影响到公路的行车安全、使用寿命与维护成本。加强路基施工的质量管理关系到我国公路建设的长远发展。当代路基施工技术的快速进步给复杂地质状况的公路施工工程带来了优良的技术保障,促使我国公路施工技术的大力进步。首先阐述了路基的定义,然后对公路路基施工的技术现状和改进措施给予了说明。 相似文献
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王萌 《交通世界(建养机械)》2015,(4)
作为世界上最大的发展中国家,我国的经济不断发展,我国的GDP也在不断增长,已经跃居为世界第二大经济大国。随着国家的发展,公路桥梁的建设工程也得到了相应的发展。好的道路桥梁施工能够带来密集的车流和较大的车辆载重等等好处,但是在我国的不少公路桥梁施工技术存在着缺陷,使得施工质量较差,产生了安全隐患。除了新的道路桥梁施工建设中存在问题,对旧桥和危桥的加固施工中也存在不足。本文通过分析我国现代道路桥梁的现状,对公路桥梁施工技术的问题及改进措施进行了探究。 相似文献
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CAI Zhi-hai 《上海交通大学学报(英文版)》2005,10(4):387-391,396
Cubic boron nitride(c-BN) films were deposited on W6Mo5Cr4V2 high speed steel(HSS) substrate implanted with boron ion by RF-magnetron sputtering. The films were analyzed by the bending beam method, scratch test, XPS and AFM. The experimental results show that the implantation of boron atom can reduce the internal stress and improve the adhesion strength of the films. The critical load of scratch test rises to 27.45 N, compared to 1.75 N of c-BN film on the unimplanted HSS. The AFM shows that the surface of the c-BN film on the implanted HSS is low in roughness and small in grain size. Then the composition of the boron implanted layer was analyzed by the XPS. And the influence of the boron implanted layer on the internal stress and adhesion strength of c-BN films were investigated. 相似文献
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