无线网状网技术与应用

无线网状网(WMNs)由网状路由器节点和客户机节点组成,其中的网状路由器节点组成了无线网状网的网络骨干,其移动性很小。他们一起为无线网状网和其他常规无线网络的客户机节点提供网络的无线接入。WMNs技术结合了中心式控制的蜂窝网与分布式控制的无线自组织网的优点,可有效克服这两种技术的缺陷并显著提高无线网络的性能,已经成为下一代无线通信网络的研究热点之一。WMNs可为无线个域网、局域网、校园网、城域网的一系列应用提供高速无线宽带接入服务。虽然目前WMNs技术发展很快,但其协议栈各层仍存在许多有待研究的课题。首先简要介绍了无线网状网的结构与特点;随后重点分析了其主要的几个应用领域;最后探讨了WMNs各协议层的研究现状与关键技术,并分析了该技术存在的问题及未来的研究方向。     

Optimizing structure for constructing a highly efficient inverted top-emitting organic light-emitting diode with stable electroluminescent spectra

We demonstrate a highly efficient inverted top-emitting organic light-emitting diode （TOLED） having stable electroluminescent spectra and color coordination with variation of viewing angles by simply tuning the reso- nance wavelength corresponding to the free emission of the emitter. Using a doped fluorescent emitting system, the inverted TOLED exhibits an enhanced maximum current efficiency of 19 cd/A and a power efficiency of 17 lm/W, which are much higher than those （11 cd/A and 5 lm/W） of the counterpart with normal structure, although both TOLEDs behave with similar stable electroluminescent spectra characteristics. The results indicate that we provide a simple and effective method of constructing an excellent inverted TOLED for potentially practical applications.     

多层套筒结构的红外消热差镜头设计与分析

重点分析了采用多层套筒与波形弹簧垫圈相结合进行热补偿的红外机械消热差镜头,根据光学软件给出的离焦量设计热补偿结构,并运用ANSYS软件对热补偿结构进行了热变形分析。经过试验测试表明,采用多层套筒实现热补偿的镜头在-40~+60℃的范围内成像质量良好。     

提升微波加热均匀性的新型电介质基底

介绍并分析了一种新型的电介质基底,旨在提升微波加热的温度分布均匀性。该基底为非轴对称结构,由FR-4环氧玻璃纤维板与氧化铝制成,其几何参数的选定是以降低球形介质样品的平均温升变异系数为目的。为探究电介质基底对微波加热均匀性的影响,采用球形马铃薯为研究对象,利用COMSOL Multiphysics多物理场仿真软件模拟微波加热过程,并计算马铃薯的平均温升变异系数。仿真结果表明：相比于不加载基底直接加热,加载电介质基底加热的马铃薯样品的平均温升变异系数降低了40%以上。最后,进行实验测试验证计算的有效性,实验结果表明：实验测试与仿真计算结果一致,温度上升曲线吻合较好,使用该电介质基底可以有效改善微波加热的均匀性。     

Combined Optical,Gravimetric, and Electrical Operando Investigation of Structural Variations in Polymeric Mixed Conductors

Bioelectronics based on organic mixed conductors offers tremendous application potential in biological interfacing, drug delivery systems, and neuromorphic devices. The ion injection and water swelling upon electrochemical switching can significantly change the molecular packing of polymeric mixed conductors and thus influence the device performance. Herein, we quantify ion and water injection, and analyze the change of microscopic molecular packing of typical polymeric mixed conducting materials, namely poly(3,4‑ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) and poly(2-(3,3′-bis(2-(2-(2-methoxyethoxy)ethoxy) ethoxy)-[2,2′-bithiophen]-5-yl)thieno[3,2-b]thiophene) (p(g2T-TT)), by integrating electrochemical quartz crystal microbalance with dissipation monitoring, in situ charge accumulation spectroscopy, and electrical current-voltage measurement. The penetration of ions and water can lead to viscous and disordered microstructures in organic mixed conductors and the water uptake property plays a more dominant role in morphological disruption compared with ion uptake is demonstrated. This study demonstrates the potential application of the combined optical, gravimetric, and electrical operando platform in evaluating the structural kinetics of organic mixed conductors and highlights the importance of concertedly tuning the hydration process, structural integrity, and charge transport properties of organic mixed conductors in order to achieve high performance and stable bioelectronic devices.     

Interfacial Proton Supply/Filtration Regulates the Dynamics of Electrocatalytic Nitrogen Reduction Reaction: A Perspective

As a promising energy carrier, ammonia synthesis by electrocatalytic nitrogen reduction reaction (eNRR) is a promising green and low-carbon ammonia synthesis strategy that can replace the traditional Haber–Bosch process. However, the development of eNRR processes is mainly severely constrained by competitive hydrogen evolution reaction (HER), and the corresponding strategies to inhibit this adverse side reaction to obtain high eNRR selectivity are still limited. In addition, for this complex reaction involving gas–liquid–solid three-phase interface and proton/electron transfer, it is great significance to analyze and summarize the existing inhibition HER strategies from the viewpoint of dynamics. In view of this, this work reviews proton supply/filtration regulation strategy in catalytic system, allowing a systematic survey of the literature focusing on interface membrane regulation (inorganic membrane and organic membrane), electrolyte regulation (metal-mediated strategy and electrolyte ion regulation strategy) and system device design (electrode structure design and electrolytic cell device design). Constructive catalytic system design guidance is also suggested to inhibit hydrogen evolution and improve NH₃ selectivity, aiming for scalable and economically feasible applications.     

一种新型温度不敏感阵列波导光栅的设计

提出了一种新型结构的阵列波导光栅。在AWG的阵列波导中嵌入多种补偿介质,补偿二阶或二阶以上温度偏移。首先从理论上推导出器件的工作原理表达式;其次给出了器件结构的设计方案,阵列波导采用同心圆结构设计,使得嵌入介质与波导垂直,有效减小了散射损耗,并显著提高了芯片的集成度。最后,对器件性能进行了评估,引入的附加损耗小于1dB;理论上实现了零温度偏移。     

利用CORDIC算法计算平方根及其FPGA实现

平方根运算作为信号处理的一种基本数据运算,在工程项目中应用广泛,但是在FPGA中直接进行平方根运算较为复杂,需要研究其高效实现方法。当利用CORDIC算法进行双曲线方程求解时,可以高效地完成平方根运算。这里首先介绍了CORDIC算法的原理,迭代结构的实现流程,及其在平方根计算中的应用。设计了两种适合于FPGA实现的CORDIC算法平方根运算的结构,并行结构和位串行结构,比较了两种结构的优缺点,并给出仿真结果。     

BNKT BZT陶瓷的制备和性能研究

采用传统固相法制备了Bi0.5(Na0.825K0.175)0.5TiO3-Ba(TiyZr1-y)O3 (BNKT-BZT)无铅压电陶瓷.运用XRD、SEM等技术表征了陶瓷的晶体结构、形貌、介电和压电性能.研究结果表明,在所研究的结构范围内,所有陶瓷样品都形成钙钛矿固溶体.陶瓷晶粒的尺寸随x、y适当的增大而增大,压电性能随x、y的增大先增大后减小,在x=0.05,y=0.2(摩尔比)时,压电常数d33=157 pC/N,介电常数εr=1 510.     

电子注通道形貌对折叠波导慢波结构的影响

折叠波导结构是一种极具潜力的太赫兹行波管慢波电路.分析了电子注通道形貌对折叠波导高频特性的影响,包括色散特性、耦合阻抗和衰减特性.仿真结果表明,相比于圆形电子注通道,矩形电子注通道的折叠波导结构色散要略微陡一些,损耗也要略微高一些.在中心频率处,矩形电子注通道结构的耦合阻抗比圆形电子注通道结构低0.5Ω左右.皮尔斯小信号理论表明,在中心频率处,矩形电子注通道结构和圆形电子注通道结构的增益速率分别为4.85 dB/cm和5.22 dB/cm,具有相似的3 dB带宽,约为6.3 GHz和7.2 GHz.粒子模拟表明,对于矩形和圆形电子注通道,54 mm(100个周期)的折叠波导慢波结构在220 GHz增益分别为24.42 dB和28.44 dB.