Robust hybrid beamforming design for millimeter-wave massive MIMO systems

Hybrid analog-digital beamforming is recognized as a promising solution for a practical implementation of massive multiple-input multiple-output(MIMO) systems based on millimeter-wave(mmWave) technology. In view of the overwhelming hardware cost and excessive power consumption and the imperfection of the channel state information(CSI), a robust hybrid beamforming design is proposed for the mmWave massive MIMO systems, where the robustness is defined with respect to imperfect knowledge or error of the CSI at the transmitter due to limited feedback and/or imperfect channel estimation. Assuming the errors of the CSI are bounded, the optimal hybrid beamforming design with robustness is formulated to a mean squared error(MSE) minimization problem. An iterative semidefinite programming(SDP) based algorithm is proposed to obtain the beamforming matrices. Simulation results show that the proposed robust design can provide more than 4 dB performance gain compared to that of non-robust design.     

图像处理技术在河工模型试验流场量测中的应用

本文系统介绍了图像处理在流场分析中的应用及摄录像系统的配置、操作和计算软件开发的一般原理，对系统的量测误差作了全面的分析并用专门设计的试验进行了检验，量测误差小于1.0％。本文研制开发的流场图像处理系统操作录活，软件功能齐全，能够快速得出全流场表面流速的大小和方向，为河工模型试验提供了一个全新的流场量测方法。     

HFETR主冷却系统设备的运行与维修

本文介绍了 HFETR 主冷却系统十年来的运行及维修情况。着重介绍了主泵的改进、热交换器的振动实验和结垢检查,蝶阀开度的限位与标定等内容。     

自增强高性能聚合物的成型工艺同力学性能间相关性研究——5.一种从实验上来测定取向聚乙烯纤维理论强度的新方法

本文提出了一种从实验上来测定取向聚乙烯纤维理论强度的新方法。它基于自增强高聚物恒定应力下持久强度动力学模型理论,采用自增强高聚物非晶区(或微区)中伸直应力集中链系数作为自变量来建立微区中伸直应力集中链(TautTie Molecule和/或Trapped Entanglement Chain)的断链动力学方程,经积分和化简后,得到了自增强高聚物的抗张强度同其起始结构、成型工艺、测试条件和断裂时间等的一般关系式。当把牵伸时间t_D远远大于松弛时间τ_3和起始分子量趋近无穷大时,结合光子强度理论后就得到了超拉伸高取向高聚物的抗张强度同理论强度、微区中应力集中伸直链(TTM和/或TEC)的重量分数(X_(e3))和热涨落等间的定量关系,并提出了一种从实验上来测定高取向纤维理论强度的新方法。用该法测定了超高分子量聚乙烯(UHMWPE)纤维的理论强度,其结果同理论计算值很好符合。     

微波干燥生产线用食品级胶辊的研制

研究确定了微波干燥生产线用胶辊的性能，试验选择了耐微波辐射的食品级橡胶配方，介绍了这胶辊的生产应用情况。     

空间异形柱框架中异形柱的力学特性

运用非线性有限元方法对空间异形柱框架及矩形柱框架作推覆分析,根据计算结果,分析空间异形柱框架中异形柱不同于矩形柱的力学性能,探讨异形柱设计中应注意的问题。     

2D Metal–Organic Framework Nanosheets with Time‐Dependent and Multilevel Memristive Switching

Metal–organic framework (MOF) nanosheets have attracted significant interests for sensing, electrochemical, and catalytic applications. Most significantly, 2D MOF with highly accessible sites on the surface is expected to be applicable in data storage. Here, the memory device is first demonstrated by employing M‐TCPP (TCPP: tetrakis(4‐carboxyphenyl)porphyrin, M: metal) as resistive switching (RS) layer. The as‐fabricated resistive random access memory (RRAM) devices exhibit a typical electroforming free bipolar switching characteristic with on/off ratio of 10³, superior retention, and reliability performance. Furthermore, the time‐dependent RS behaviors under constant voltage stress of 2D M‐TCPP–based RRAMs are systematically investigated. The properties of the percolated conducting paths are revealed by the Weibull distribution by collecting the measured turn‐on time. The multilevel information storage state can be gotten by setting a series of compliance current. The charge trapping assisted hopping is proposed as operation principle of the MOF‐based RRAMs which is further confirmed by atomic force microscopy at electrical modes. The research is highly relevant for practical operation of 2D MOF nanosheet–based RRAM, since the time widths, magnitudes of pulses, and multilevel‐data storage can be potentially set.     

铑-钌双金属催化剂用于丁腈橡胶加氢最佳工艺参数

用作者研制的铑 -钌双金属配位化合物催化剂 (BMSC)对丁腈橡胶溶液进行均相加氢 .采用正交设计方法 ,考察温度、压力、催化剂用量和反应时间对加氢度的影响 ,并用极差分析方法对正交试验结果进行分析 ,得到了最佳的加氢工艺参数 .在反应温度为 145℃、氢气压力 1.2MPa、反应 4h的条件下 ,催化剂用量为NBR胶重的 0 .2 5 % ,产物加氢度可达 98%以上 .     

草酸二甲酯气相加氢反应中铜基催化剂改性方法研究进展

介绍近年来草酸二甲酯气相加氢反应中铜基催化剂改性方法,总结通过制备方法、催化剂载体和助剂等改性对催化反应性能的影响。重点概述不同改性方法下制备的催化剂对反应物转化率和产物选择性的影响,并解释采用不同改性方法时催化剂催化活性变化的原因。