无线多址信道中的协作模型研究

在无线多址信道环境下,为了充分利用协作分集技术提高系统的传输速率和通信质量,引入了多址接入中继信道（MARC）模型。通过加入一个专门的中继节点,MARC模型中的发送节点类似操作在普通的多址信道下,从而使得现有的系统可平滑过渡到协作系统,实用性强。把MARC模型应用在直序扩频CDMA系统中,在Rayleigh信道下对其误码率进行仿真,结果表明,采用MARC模型的协作网络能获得显著的性能增益。     

Research on the low complexity adaptive power allocation algorithm in cooperative systems

Cooperative diversity is a new technology to improve bit error rate(BER)performance in wireless communications.A new power allocation algorithm to improve BER performance in cellular uplink has been proposed in this paper.Some existing power allocation schemes were proposed for the purpose of maximizing the channel capacity or minimizing the outage probability.Different from these schemes,the proposed algorithm aims at minimizing the BER of the systems under the constraint of total transmission power.Besides this characteristic,the proposed algorithm can realize a low complexity real-time power allocation according to the fluctuation of channels.Simulation results show that the proposed algorithm can decrease the BER performance of the systems effectively.     

Spectral efficient half-duplex relaying with interference suppression

Two-hop relaying systems suffer spectral efficiency loss due to the half-duplex property of relays. This paper proposes an efficient relaying protocol which can recover the spectral efficiency loss but still work with half-duplex relays. However, there exists inter-relay interference which degrades the performance of the protocol. With this consideration, a power control policy is derived to suppress the interference using game theory, and then an algorithm is given to facilitate distributed implementation. Furthermore, impact of deploying more destination antennas on performance of the relaying protocol is investigated. Simulation results show that, with the power control policy, the proposed relaying protocol can achieve high spectral efficiency.     

SNR-based weighted cooperative spectrum sensing in cognitive radio networks

Cooperative spectrum sensing (CSS) is an approach to confront fading environment. However, in conventional cooperative spectrum sensing (CCSS), the difference among the secondary users (SUS) is ignored when SUS suffer from different fading. In this article, a signal-to-noise ratio (SNR)-based weighted spectrum sensing scheme is proposed to improve the sensing performance. The sensing performance of the weighted spectrum sensing scheme is then derived. Considering the minor contribution of the SUS with small weighted factor, a selective CSS scheme is proposed, where SUS with low SNR are not selected into cooperative spectrum sensing. The simulation results confirm the analytical results. And the performance of weighted scheme is better than that of conventional schemes. In the case where the SNR of SUS are randomly distributed, the performance of selective scheme is almost the same as the weighted scheme while the number of cooperative SUS is reduced to save the consumption of system resource in cooperation with little additional complexity.     

厦门时代广场复杂连体隔震结构整体分析

针对厦门时代广场商业区这一复杂连体顶托一网架的环形建筑采用整体建模方法,分别进行了水平两方向多遇地震和罕遇地震作用下的非线性动力时程计算及分析,并与无连体结构进行了对比研究。整体模型的动力分析结果表明,连廊与主体之间组合隔震系统后,连廊的滑动端平均滑动距离的减震效果自下而上逐渐显著;各单体建筑楼层剪力由于连廊与顶部网架的动力影响,底部两层出现楼层剪力放大,但其余楼层剪力明显减小;网架与托柱之间采用柱顶组合隔震系统后,网架柱底总剪力减震效果极为显著,底部剪力分布更均匀,对调整下部结构内力分布,减小结构在动力作用下的反应是显著的。     

基于多智能体的编队协同空战战术规划

把编队看成一个多Agent系统,编队中的长机和僚机都看成是Agent。首先叙述了BDOTI-Agent的逻辑结构,然后提出基于多Agent的编队协同空战战术规划合作求解的方法,合作求解过程分为任务形成、合作产生、团队初步形成、任务分解、团队最终形成、角色指定和子任务分配、执行任务等7个阶段。最后举例说明了合作求解的过程。     

Cooperative Activation in the Hydrolytic Kinetic Resolution of Epoxides by a Bis‐Cobalt(III)salen‐Calix[4]arene Hybrid

A chiral, bimetallic cobalt(III)salen‐calix[4]arene hybrid structure was prepared and tested in the hydrolytic kinetic resolution (HKR) of racemic epoxides. Kinetic studies have revealed that the two catalytic units on the upper rim of the calixarene scaffold are able to activate the reactants in a cooperative and primarily intramolecular mode. High enantioselective behaviour was observed and besides, a higher stability was found for the bimetallic catalyst as compared to a monometallic reference complex.     

基坑斜撑支护体系先拆后撑法研究

从斜撑系统的协同变形理论出发,利用最小势能解,提出了分区段先拆后撑的思路,推导了该类支撑结构在分段拆撑过程中,拆撑区段长度的计算方法。并结合具体工程实例,对该计算理论和结果加以验证,证实该方法是可行的,从而可以为今后该类支护形式的拆撑设计和施工提供借鉴。     

南京地铁二号线钟灵街站防水设计

钟灵街站是南京地铁二号线一期工程的一个地下车站,防水设计是设计的关键技术之一。通过优化混凝土配合比,降低水泥水化热,合理设置施工缝、诱导缝,取消了主体结构上的后浇带和变形缝,实现了主体结构的整体浇筑,增进了主体结构的自防水功能。针对不同的部位,采用不同的附加防水措施,侧壁和底板采用预铺式冷自粘防水卷材,顶板采用单组分聚氨酯涂膜防水层。另外,车站和通道接口部位施工缝采用预埋注浆技术,变形缝采用中埋注浆止水带。通过上述措施的综合运用,钟灵街站的防水设计满足了防水功能要求。     

以科学发展观为指导构建保持研究生党员先进性的长效机制

通过分析新时期研究生党建的特点和科学发展观对党建的内在要求,指出在科学发展观指导下构建研究生党员保持先进性的长效机制,必须结合研究生党员群体的特点,坚持以学生为本,充分调动主观能动性,发挥研究生党员的主体作用,把党的先进性要求与研究生党员的个体发展、价值追求、宗旨观改造、自律他律结合起来,把满足学生全面需求和促进学生全面发展作为教育的根本出发点和落脚点。通过全面协调、统筹兼顾和不断创新学习教育机制、健全激励机制、强化联系群众机制、完善考评与监督管理机制,最终形成研究生党员常保先进性的长效机制,达到培养人才的目的。