Space–Time Power Schedule for Distributed MIMO Links Without Instantaneous Channel State Information at the Transmitting Nodes

A space-time optimal power schedule for multiple distributed multiple-input multiple-output (MIMO) links without the knowledge of the instantaneous channel state information (CSI) at the transmitting nodes is proposed. A readily computable expression for the ergodic sum capacity of the MIMO links is derived. Based on this expression, which is a non-convex function of power allocation vectors, a projected gradient algorithm is developed to optimize the power allocation. For a symmetric set of MIMO links with independent identically distributed channels, it is observed that the space-time optimal power schedule reduces to a uniform isotropic power schedule when nominal interference is low, or to an orthogonal isotropic power schedule when nominal interference is high. Furthermore, the transition region between the latter two schedules is seen to be very sharp in terms of nominal interference-to-noise ratio (INR). For MIMO links with correlated channels, the corresponding space-time optimal power schedule is developed based on the knowledge of the channel correlation matrices. It is shown that the channel correlation has a great impact on the ergodic capacity and the optimality of different power scheduling approaches.     

纳米加工和纳米电子器件

介绍了电子束曝光技术、EUV光刻技术和X射线光刻技术的进展;对各种纳米电子器件如单电子器件、共振隧穿器件和分子电子器件的研究现状及面临的主要挑战进行了讨论。     

Viterbi译码器的硬件实现

介绍了一种Vkerbi译码器的硬件实现方法。设计的基于硬判决的Viterbi译码器具有约束长度长（9)、译码深度深（64)的特点。为了兼顾硬件资源与电路性能两个方面，在设计中使用了4个ACS单元，并根据Xilinx Virtex系列FPGA的结构特点．利用FPGA内部的BlockRAM保存汉明距离和幸存路径，提高了译码速度。     

虚拟企业图纸数据传输

图纸数据是企业间合作需交换的一种重要的信息。本文分析了虚拟企业环境下企业之间交换图纸数据的要求，提出了一种具体的解决方案，并给出实例。     

磨损自补偿添加剂在成品油中的摩擦学效应

利用四球试验机考察了二聚酸－3－氯－2－羟基丙单酯（DAE）在4种成品油中的摩擦学性能。试验结果表明，DAE添加剂在L－HM68液压油和L－DAB100空压机油中具有良好的适应性，使其承载能力增强，摩擦系数降低及耐磨性增强；DAE在L－CKE涡轮蜗杆油中使耐磨性增强；DAE在L－CKC150齿轮油中虽使承载能力提高，减磨性增强，但有使耐磨性减小的趋势，说明DAE在不同的油中有不同的性能。     

碳纳米管的制备及研究

介绍了在直流电弧放电法制备富勒烯过程中，从阴电极表面收集到大量的碳纳米管及巴基葱，产生率达到５０％，并用电子显微镜对其进行了观察和初步研究。     

高发射率节能涂料及其应用

讨论了高发射率涂料节能的条件，了一种在1000℃仍保持高发射率的优质涂料，并解决了涂料与金属基体的粘结工艺，用此涂料制成增强辐射电阻带和复合炉衬，得到的新炉比旧炉节能20－40％。     

Modeling and control of magnet power supply system with switch-moderipple regulator

This paper presents the dynamic performance analysis and closed-loop design of a new power supply system for a high-current magnet load. This new system introduces a series switch-mode ripple regulator (SMRR) into a phase-controlled rectifier to improve system dynamic response and to reduce the harmonic content in the magnet current. In this paper, the new system control configuration is explained. The small signal dynamic model is established. The function of the SMRR as a speed-up feed-forward path during dynamic transients is assessed. The criteria of the closed-loop regulator design are identified. The theoretical analyses are accompanied by computer simulation and experimental results. The systematical design procedure is outlined by an example which offers better performance than ever reported on high-current magnet power supplies in terms of fast dynamic response (closed-loop bandwidth several kHz) and low harmonic content (less than 10 ppm) in the magnet current