大规模MIMO多小区多用户TDD系统导频污染抑制方法

针对大规模MIMO系统中导频污染问题,提出一种基于路径损耗执行用户分组的导频调度策略（pilot scheduling based on path loss to perform user grouping,PLUG）,该策略以用户受导频干扰程度为依据将用户划分为中心用户组和边缘用户组,受导频污染较轻的中心用户分配相同导频,受导频污染严重的边缘用户分配正交导频,从而抑制导频污染的影响。PLUG策略假定每个小区的边缘用户数相同,为提高PLUG策略灵活性,进一步提出一种改进的基于路径损耗执行用户分组的导频调度策略（improved pilot scheduling based on path loss to perform user grouping,IPLUG）,该策略利用判决参数实现每个小区边缘用户数的动态选取,成功地避免一些信道条件好的用户被误划为边缘用户造成导频开销浪费,或信道条件差的用户被误划为中心用户导致通信质量下降,提高了用户分组的准确性和合理性。理论分析和仿真结果表明,所提策略均能在不明显降低中心用户性能的前提下显著提高小区边缘用户的信道估计归一化MSE、上行链路SINR和上行可达速率。由此可知,所提策略可有效抑制大规模MIMO系统的导频污染并降低通信中断概率。     

基于阵列域大尺度衰落模型的1-bit大规模MIMO系统性能的分析

该文研究在阵列域大尺度衰落模型下,基站端天线仅仅配备了1-bit精度的模数转换器时大规模MIMO系统的性能。首先给出了系统采用最大比合并接收机时,用户上行可达速率的闭式表达式。然后分析了1-bit系统的功率效率性能,并将该1-bit系统与传统的具有无穷精度模数转换器的系统性能相比较。通过计算机仿真验证了该文的分析结果。该文指出基站端可以安装更多的天线来弥补1-bit精度的模数转换器所造成的性能损失。     

《大学计算机》MOOC研究及应用

MOOC是一种新型的在线课程模式,目前在国内外受到很多高校及学者的关注。介绍了MOOC的起源发展,阐述了其所面临的机遇和挑战,分析了我院实践应用的状况,所遇到的问题及解决方法。     

某块状硫化物型铜铅锌多金属矿选别工艺优化研究

新疆某复杂难处理铜铅锌多金属矿矿物组成复杂,由于次生铜离子的活化和弥散分布的金银矿物对黄铁矿和闪锌矿的活化作用,造成黄铁矿和闪锌矿具有良好的可浮性,而铅矿物嵌布粒度细,浮游性较差,采用石灰抑制黄铁矿和采用亚硫酸钠抑制闪锌矿时都对铅矿物造成较明显的抑制作用.生产中采用"铜铅混合浮选-铜铅分离-锌浮选"的工艺流程,存在有价...     

Radiation loads on the ITER first wall during massive gas injection

Unmitigated disruptions in ITER can produce strong localized surface damage on the first wall (FW). Massive gas injection (MGI) systems are being designed to dissipate a large fraction of the plasma stored energy at the disruption thermal quench (TQ) and hence reduce the consequences for FW components. The stored energies can be high enough, however, for there to be potential for the photon flash at the MGI TQ to drive local melting of beryllium FW components. To estimate the poloidal distribution of FW surface temperatures, the MGI process is being simulated using the 2D code TOKES, assuming toroidal symmetry. High pressure neon injection, assimilation and transport of injected impurities through the entire plasma volume are modelled. The output of these simulations is used by the melt motion code MEMOS to assess the resulting maximum surface temperature and the regimes with melting on the FW surface.     

大体积防辐射泵送重混凝土在芜湖弋矶山医院工程中的应用

根据设计部门对防辐射混凝土的要求,选择铁矿石作主要集料,并运用集料填充理论适当复合其他优质集料成功配制了大体积防辐射泵送混凝土,并成功运用到弋矶山医院工程。     

Energy potential of a Massive Solar-Thermal Collector design in European climates

The aim of this work is to investigate the energy potential of using exposed concrete structures as solar energy absorbers (here denoted with the general term of Massive Solar-Thermal Collectors, MSTCs) during the heating period and in particular the design of a Concrete Solar Collector (CSC) is then presented. The CSC is a particular kind of MSTC, conceived as an exposed free standing structure that embeds a coiled pipe heat exchanger in a massive-concrete matrix. A numerical design model has been developed and parametric simulations have been conducted in order to get a figure of the energy potential of the CSC under different European climate conditions. The CSC has reached an energy yield of 460.77 kW h/m²/y and an average heat flux of 93.07 W/m² for the reference climate of Stuttgart (Germany) during the winter season (inlet fluid temperature of −5 °C and mass-flow rate of 45 kg/h/m²). The Elementary Effect Method has been adopted as Sensitivity Analysis procedure with the aim of understanding the dependency of design parameters on the energy output. Finally, an economic analysis has been carried out by comparing investment costs and energy outputs.     

5G NSA组网结构下用户体验提升研究

针对现阶段5G NSA组网结构模式下,开展5G特性研究。在研究5G及其相关技术特点的基础上,结合实际测试与分析结果,通过对DC双连接、时隙配比以及MassiveMIMO差异性3个方面进行测试对比,分析5G NSA组网性能,为提升NSA组网结构下的用户体验提供参考。     

水平井开发块状边底水油藏的影响因素分析——以宋家垛油田周43块为例

由于水平井能有效抑制底水锥进,与直井相比具有很大优势,在边底水油藏中应用非常广泛.针对水平井的开发特征,运用数值模拟法,结合生产动态及物理模型试验方法从静态因素和生产动态因素两方面分析,总结了影响水平井开发块状边底水油藏的各项因素,提出了“水平井临界渗透率级差”概念,分析了油藏开发中后期驱动方式的转变,以期对同类油藏的...     

非视距环境下Massive MIMO信道的构建与分析

随着下一代移动通信研究的深入,Massive MIMO 技术已成为业界研究的热点。针对 Massive MIMO 系统特有的天线体积大、信道近场非平稳的特性,构建出较真实的信道模型,该模型适用于 Massive MIMO非视距、瑞利平坦衰落环境。在系统仿真中,基站侧采用128根线形排列的天线,基站天线到信道散射体的导向矩阵由精确的波程差来确定,得到发射端相关矩阵,并结合Kronecker模型构建信道。结合不同的预编码方法和散射体分布情况,对比分析了其对 Massive MIMO信道容量的影响。该信道的构建与分析能更准确地反映信道特性,具有较强的理论价值和实践意义。