OFDM系统中基于线性预编码技术的均衡方法

在快速移动环境中,子载波间干扰(ICI)是恶化OFDM系统性能的重要因素。为抑制OFDM系统中的ICI,采用了一种基于线性预编码技术的迫零均衡方法,并对其在无冗余情形下的误码率(BER)性能进行了理论分析,推导出了BER最优的线性预编码矩阵的选取准则。仿真结果表明,在较高信噪比条件下,所用的方法能有效抑制ICI和显著改善OFDM系统的误码率性能。     

洁净室气态分子污染物的监测技术

随着微电子工业工序复杂性的增加和产品尺寸的不断缩小,气态分子污染物(AMC)对产品的影响成为洁净室环境控制中重点关注的问题。文章介绍了洁净室中AMC的定义,重点阐述了AMC的监测技术。     

硼离子选择注入制备多孔硅微阵列

根据 p型硅和 n型硅不同的制备多孔硅的工艺条件 ,利用硼离子选择注入 ,在 n型硅片上的局部微区域 ,形成易于腐蚀的 p型硅 ,用电化学腐蚀方法制备出图形化的多孔硅阵列 .省去了传统掩膜腐蚀工艺的掩膜材料的选取与制备以及后道工艺中掩膜材料的清除等工艺 ,克服了掩膜材料掩蔽效果较差以及存在横向钻蚀等缺点 .通过 AFM,SEM测试 ,证明该方法的效果很好     

Tough Transient Ionic Junctions Printed with Ionic Microgels

Emerging soft ionotronics better match the human body mechanically and electrically compared to conventional rigid electronics. They hold great potential for human-machine interfaces, wearable and implantable devices, and soft machines. Among various ionotronic devices, ionic junctions play critical roles in rectifying currents as electrical p–n junctions. Existing ionic junctions, however, are limited in electrical and mechanical performance, and are difficult to fabricate and degrade. Herein, the design, fabrication, and characterization of tough transient ionic junctions fabricated via 3D ionic microgel printing is reported. The 3D printing method demonstrates excellent printability and allows one to fabricate ionic junctions of various configurations with high fidelity. By combining ionic microgels, degradable networks, and highly charged biopolymers, the ionic junctions feature high stretchability (stretch limit 27), high fracture energy (>1000 Jm⁻²), excellent electrical performance (current rectification ratio >100), and transient stability (degrade in 1 week). A variety of ionotronic devices, including ionic diodes, ionic bipolar junction transistors, ionic full-wave rectifiers, and ionic touchpads are further demonstrated. This study merges ionotronics, 3D printing, and degradable hydrogels, and will motivate the future development of high-performance transient ionotronics.     

An Efficient One-Arrow-Two-Hawks Strategy Achieves High Efficiency and Stable Batch Variance for Benzodifuran-based Polymer Solar Cells

With the development of organic solar cells (OSCs), the high-performance and stable batch variance are becoming a new challenge for designing polymer donors. To obtain high photovoltaic performance, adopting polymers with high molecular weight as donors is an ordinary strategy. However, the high molecular weight need to subtly control the reaction time and state, inevitably caused batch-to-batch variations. Herein, a strategy of steric effect is applied to benzodifuran (BDF)-based polymer by introducing different positions of Cl atom, producing two polymers PBDFCl-1 and PBDFCl-2. The more twisted side chains conformation not only achieve the control of moderate molecular weight for PBDFCl-2, but also easily form molecular stacking through adopting BDF unit and maintain sufficient polymeric crystallinity. Due to the optimized stacking mode and good blend miscibility, PBDFCl-2-based device exhibitsa more elegant power conversion efficiency (PCE) of 17.00% compared to PBDFCl-1-based device. This is the highest efficiency record for BDF-based binary OSCs. Meanwhile, the PCE device variation of the different molecular weights for PBDFCl-2 is little, indicating the reduction of the batch variation. Therefore, smartly using steric effect of Cl atom in strong crystalline BDF unit can form efficient molecular stacking regulations and realize the coordination of high-performance and stable batch variance.     

Boosting Redox Kinetics of Sulfur Electrochemistry by Manipulating Interfacial Charge Redistribution and Multiple Spatial Confinement in Mott–Schottky Electrocatalysts

The serious shuttle effect and sluggish reaction kinetics intrinsically handicap the practical application of Li-S batteries. Herein, a unique 3D hierarchically porous Mott–Schottky electrocatalyst composed of W₂C quantum dots (QD) spatially confined in nitrogen-doped graphene microspheres (NGM) is proposed for regulating the kinetics of sulfur electrochemistry. Experimental and theoretical results disclose a spontaneous charge rearrangement and induce built-in electric field across the W₂C QD/NGM heterojunction interface, contributing to reduced energy barrier for both polysulfides reduction and Li₂S oxidation during entitle discharge/charge processes. Furthermore, the ultrasmall W₂C QD with high electrocatalytic activity and superior conductivity can promote the conversion of S species, while the hierarchically porous microspheres assembled from wrinkled graphene nanosheets not only can efficiently inhibit the polysulfides shuttling via multiple spatial confinement, but also provide abundant inner space for stable reservation of active S, highly conductive networks, and maintain the structural integrity of cathode during consecutive cycling. Consequently, Li-S batteries employed with the designed W₂C QD/NGM-based cathode exhibit outstanding electrochemical properties even at a high sulfur loading. The superior performance combined with the simplicity of the synthesis process represents a promising strategy for the rational design of advanced electrocatalyst for energy applications.     

双波段比色精确测温技术

非接触红外辐射测温具有响应速度快、准确、便捷等优势。为实现中低温(50~400℃)物体温度的精确测量,根据双波段比色测温原理,搭建了双波段比色测温试验系统。首先对试验系统所用的试验器件进行精确标定,得到拟合曲线,用多种插值算法对曲线进行校正。然后,用设定温度的面源黑体作为试验目标来进行试验温度数据采集。实验结果表明:搭建的双波段试验系统不需要知道目标发射率,也能较为精确地得到中低温物体的真实温度。当系统标定置信度为0.95 时,物体的标准偏差在3℃以内。验证了搭建测温系统的正确性,实验装置的搭建对中低温物体真实温度的精确测量具有重要的研究意义。     

Frequency resource allocation strategy with QoS support in hybrid cellular and Device‐to‐Device networks

Hybrid networks, comprising a conventional cellular network overlaid with Device‐to‐Device (D2D), offer efficient way to improve system throughput. In this paper, a novel orthogonal frequency‐division multiple access channel‐assignment method is proposed for hybrid network. The proposed approach is optimal in terms of throughput and is subjected to a sensible QoS requirement, which guarantees that macrocell and D2D achieve a prescribed data rate and outage probability, respectively. Our solution consists of two phases. In the first phase, the minimum sub‐channels are allocated to the macrocell to satisfy their data rate requirements. This problem is mapped to the 0‐1 Knapsack Problem and solved by integer programming based Lagrange dual approach. In the second phase, the redundant sub‐channels are allocated to D2D pairs to maximize the throughput of D2D networks. An interference management scheme is proposed to guarantee the outage probability of D2D communications. A cluster is taken as the unit for frequency reuse among D2D pairs. The problem of clustering is mapped to the MAX k‐CUT problem in graph theory and is solved by graph‐based heuristic algorithm. Extensive simulations demonstrate the superior performance of the proposed solution compared with the existing scheme. Copyright © 2014 John Wiley & Sons, Ltd.     

利用EALCD的数字全息干涉术

基于电寻址液晶(EALCD)读写图像实时、衍射效率高的特性,设计了以EALCD和CCD为关键器件的数字全息干涉系统.系统满足空间带宽积,时间、空间相干度和偏振度的要求,提高了干涉条纹的对比度,降低了散斑噪声等影响,实现了数字全息干涉术的高精度测试.利用双曝光全息干涉术原理,应用Matlab编程取代传统相移术中的压电位移...     

家用电器微波炉对WLAN、蓝牙的干扰测试分析

无线通信已经融入到家庭里的每一个角落,成为生活中的一部分.家庭无线Wi-Fi设备、蓝牙设备、无绳电话等,在带给我们生活便捷的同时,也给家庭电磁环境带来了考验.由于ISM频段的开放性,在当今的家庭电磁环境中,越来越多的无线设备工作在该频段,同时还存在其他可能会在ISM频段产生辐射干扰的电子设备,例如：计算机和微波炉.这使得家庭电磁环境变得越来越恶劣,于是不得不对各种电子设备在此恶劣工作环境下的电磁兼容性进行研究和分析.