Impact of channel estimation error on channel capacity of multiple input multiple output system

In order to investigate the impact of channel estimation error on channel capacity of multiple input multiple output （MIMO） system, a novel method is proposed to explore the channel capacity in correlated Rayleigh fading environment. A system model is constructed based on the channel estimation error at receiver side. Using the properties of Wishart distribution, the lower bound of the channel capacity is derived when the MIMO channel is of full rank. Then a method is proposed to select the optimum set of transmit antennas based on the lower bound of the mean channel capacity. The novel method can be easily implemented with low computational complexity. The simulation results show that the channel capacity of MIMO system is sensitive to channel estimation error, and is maximized when the signal-to- noise ratio increases to a certain point. Proper selection of transmit antennas can increase the channel capacity of MIMO system by about 1 bit/s in a flat fading environment with deficient rank of channel matrix.     

基于S7-200 PLC和TP170A的船舶中央空调综合控制系统的实现

本文利用S7-200PLC实现船舶中央空调的综合控制和管理，对制冷压缩机进行有级能量调节，温度和湿度实现PID和PWM控制，达到了节能和操作方便的效果。     

中原城市群道路交通与土地利用互动关系研究

文章运用系统分析法及文献资料法分析了中原城市群土地利用与道路交通的特点以及二者的互动关系。分析认为:中原城市群的建设用地矛盾突出,土地利用集约化程度不高;道路交通条件的改善促使本地土地价格上涨,加速了城市边缘区土地的开发;土地的开发利用,产生了巨大的交通需求,道路交通的增长不能完全满足高强度土地开发利用的需求。     

厂拌热再生设备选型对沥青混合料再生质量影响探析

本文就沥青厂拌热再生设备选型进行阐述,探讨了不同种类厂拌热再生设备对沥青混合料的再生技术产生的作用等。并由此对高等级公路沥青路面养护维修工程中沥青混合料再生利用技术的完善具有一定参考价值。     

氟化钙输出镜炸裂原因试验研究

氟化钙输出镜是氟化氘激光器上的重要光学元件,本文针对氟化氘激光器出光过程中氟化钙输出镜出现炸裂的现象,用多种检测方法进行试验研究,分析了氟化钙输出镜炸裂的影响因素。     

Merging bus routes in Hong Kong’s central business district: Analysis and models

A significant portion of the 200,000 people working in Hong Kong’s central business district (CBD) relies on buses as their primary means of transport. During peak hours, nearly a thousand double-decker buses pour into a tiny area of 150 ha. This causes traffic congestion and air pollution. Moreover, given that the flow is uni-directional (into the CBD in the morning and out of the CBD in the afternoon), the occupancy of buses in the CBD is actually low.In this paper, we propose to reduce traffic congestion and to increase bus occupancy by merging bus routes. We describe the peculiar situation of the CBD in Hong Kong and explain the necessary conditions for the possible success of merging routes. Our analysis shows that merging will lead to an overall benefit for all parties, including government, bus operators, and passengers. The actual merging decisions, which routes to merge and at what frequencies buses should run, are determined by a mathematical model. The model also shows quantitatively the benefits of merging routes and the impacts of other factors. The procedure that we follow and the model that we adopt can be applied to other CBD.     

武汉市中环线西环段8+725～9+030段软基处理

武汉市中环线西环段途径沟渠纵横 ,湖塘发育的地区 ,其土壤含水量大、孔隙率高。如何处理好软土地基是设计中的一个关键问题。本文结合在 8+72 5～ 9+0 3 0段软基采用粉喷桩处理的工程实践 ,对处理情况作了分析 ,并就粉喷桩设计、施工、补强和检测中的有关问题进行探讨。     

中央自动充放气铜管开裂失效分析

通过对中央充放气铜管宏观检查、化学成分分析、硬度测试、氨熏试验等结果分析,确定了其开裂原因是由于工件冷变形后未消除残余应力,加之装配后产生的应力,在露天放置又受到大气雨水等共同作用,形成了腐蚀环境,导致产生应力腐蚀裂纹。并提出了去应力退火预防中央充放气铜管开裂,效果良好。     

结合蒙西至华中通道引入方案浅析岳阳铁路地区总图格局

结合岳阳铁路地区既有客运和货运系统现状,综合考虑蒙西至华中地区铁路煤运通道及地区内既有铁路技术标准,研究蒙西至华中通道岳阳铁路地区引入方案;通过对既有铁路地区客货运系统布局的分析,研究蒙西至华中通道引入后的铁路地区总图规划,以充分利用铁路地区既有客货运设施为前提,最终确定规划机场西侧方案为推荐方案;充分利用既有客货运设施,规划铁路地区总图格局,对重载煤运通道引入既有铁路地区具有借鉴意义。     

城市中心区地铁车站导向设施设置的探讨——以南京市新街口地铁站为例

城市中心区地铁车站与商业开发相结合,使得地下空间人流量大,结构复杂。在这样的空间里,建立完善的、人性化的标识导向系统是提高客流疏散效率的有效方法。以南京市新街口地铁站的导向设施为例,分析了当前地铁车站导向设施设置中存在的问题,并提出了地铁车站导向设施设置的改进建议。