基于侧边抛磨光纤光栅双反射峰的折射率传感器

介绍了一种利用具有双布拉格反射峰效应的侧边抛磨光纤光栅(SPFBG)进行折射率测量的新型光纤折射率传感器.该传感器基于由轮式侧边抛磨法加工而成的侧边抛磨光纤光栅,通过将折射率液覆盖一部分抛磨区的方法在一根光纤光栅上获得两个布拉格反射峰.这两个布拉格反射峰差值与覆盖材料折射率有关,而与光纤光栅所受应力与环境温度无关,因此用这两个布拉格反射峰差值作为测量量对折射率测量,可减小应力与环境温度的影响,实现高精度的折射率传感测量.实验表明,当维持环境温度恒定时,光纤光栅轴向应变在线性变化范围内,该传感器测量折射率时不受应力与温度变化的影响.折射率液在1.4298～1.4479范围内,该传感器的折射率测量分辨率为0.0001.     

一种基于流水线的SpaceWire路由器研究

SpaceWire路由器是面向Spacewire总线网路互联的设计,它解决了SpaceWire总线只能点对点连接的问题,并提供了通用标准接口和规范进行SpaceWire网络的建立.提出了一种基于流水线技术的SpaceWire路由器,它是利用FP-GA设计来实现无阻塞的交换矩阵,并且利用流水线原理提高系统的并行工作速度,以提高SpaceWire路由器的交换速度.目前经过验证的速度已达200 Mb/s.且正在不断改进中.     

Polyphenylene Dendrimer‐Templated In Situ Construction of Inorganic–Organic Hybrid Rice‐Shaped Architectures

A novel dendrimer‐templating method for the synthesis of CuO nanoparticles and the in situ construction of ordered inorganic–organic CuO–G2Td(COOH)₁₆rice‐shaped architectures (RSAs) with analogous monocrystalline structures are reported. The primary CuO nanoparticles are linked by the G2Td(COOH)₁₆ dendrimer. This method provides a way to preserve the original properties of primary CuO nanoparticles in the ordered hybrid nanomaterials by using the 3D rigid polyphenylene dendrimer (G2Td(COOH)₁₆) as a space isolation. The primary CuO nanoparticles with diameter of (6.3 ± 0.4) nm are synthesized via four successive reaction steps starting from the rapid reduction of Cu(NO₃)₂ by using NaBH₄ as reducer and G2Td(COOH)₁₆ as surfactant. The obtained hybrid CuO–G2Td(COOH)₁₆ RSA, formed in the last reaction step, possesses a crystal structure analogous to a monocrystal as observed by transmission electron microscopy(TEM). In particular, the formation process of the RSA is monitored by UV–vis, TEM, and X‐ray diffraction. Small angle X‐ray scattering and Fourier transform infrared spectroscopy are used to investigate the role of the dendrimer in the RSA formation process. The obtained results illuminate that Cu²⁺? COO^? coordination bonds play an indispensable role in bridging and dispersing the primary CuO nanoparticles to induce and maintain the hybrid RSA. More importantly, the RSA is retained through the Cu²⁺? COO^?coordination bonds even with HCl treatment, suggesting that the dendrimers and Cu²⁺ ions may form rice‐shaped polymeric complexes which could template the assembly of CuO nanoparticles towards RSAs. This study highlights the feasibility and flexibility of employing the peculiar dendrimers to in‐situ build up hybrid architectures which could further serve as templates, containers or nanoreactors for the synthesis of other nanomaterials.     

基于多分支卷积神经网络的车辆图像比对方法

为了更有针对性地从车辆图像的不同区域提取出独特的图像特征,提出基于多分支卷积神经网络的车辆图像比对方法.首先,根据车牌定位结果获取比对车辆的车脸图像,并根据车脸图像的纹理丰富度将车脸图像划分为多个图像块;其次,使用多分支卷积神经网络分别提取各车脸图像块的深度特征;最后,通过计算车脸图像深度特征的相似度判定比对的车辆图像是否属于同种车型.实验表明,提出的方法能够提取有效的车辆图像各区域的深度特征,获得良好的车辆比对准确率,可用于套牌车辆识别.     

功率AlGaN/GaN肖特基二极管结构优化设计

利用Silvaco-ATLAS软件设计了AlGaN/GaN肖特基二极管(SBD)的基本结构,主要针对功率器件的关键参数—击穿电压进行仿真模拟,分析对比了AlGaN/GaN异质结中Al的组分、二极管阳极与阴极的间距Lac、场板的引入和长度以及FP结构下钝化层Si₃N₄的厚度t对二极管击穿特性的影响。结果显示,Lac的增加、场板的引入和FP结构下钝化层厚度t的变化均对二极管的击穿特性有所优化,但同时,Al组分的增加和Lac的增加对二极管引入了不同程度的负面影响。仿真结果对器件的实际制作具有一定的指导意义。     

空间网络中基于身份的分布式密钥管理研究

为解决在空间网络中实施集中式密钥管理困难以及维护公钥证书开销过大等问题,论文设计了一种基于身份的分布式密钥管理方案。结合空间网络特点,给出了分布式私钥生成中心的构建方法。并利用Boneh和Franklin提出的基于身份的公钥加密体制,设计了私钥更新、主密钥分量更新和会话密钥协商等策略。分析和仿真验证,该方案能满足安全要求,具有较好的扩展性。     

BP神经网络在异向介质基本结构分析中的应用

为了减少传统数值分析法由于厚度谐振而引起的结果错误问题,实现异向介质高分析精度与高效率的共存,建立基于反向传播多层前馈型神经网络(BP神经网络)的异向介质电磁特性与介质敏感结构参数之间的神经网络模型,对异向介质的基本结构进行分析。实验结果表明,采用量化共轭梯度法的分析时间为145.535648 s,训练均方误差为0.00020679,所得结果与全波分析相吻合,满足工程要求。有效地克服了再次预测过程中提取参数的不稳定性,为异向介质的分析提供一种快速而准确的方法。     

一种可重构流媒体调度算法

针对现有流媒体算法在异构环境下性能恶化的问题,论文提出一种支持用户异构性的可重构流媒体调度算法RSMS算法。该算法引入了追赶流的概念,能重构追赶流的速率来服务于具有不同接收带宽的异构用户,并最终通过流合并达到资源共享的目的。分析了RSMS算法的最佳组播调度间隔、所需的平均服务器带宽和服务器带宽需求分布。仿真实验表明该算法简单高效,可扩展性好。     

基于和差波束极化特性的目标极化散射矩阵测量方法研究

该文建立了一种基于常规单脉冲体制的目标全极化散射矩阵测量算法。首先证明了该型雷达天线具有复杂的极化结构,并且对回波信号的极化特性有一定的敏感性。利用单脉冲雷达和差通道的极化特性在获取目标角度信息的同时利用一个脉冲重复周期即可完成目标极化散射矩阵的测量,降低了全极化单脉冲雷达研发的系统复杂度和设计成本,通过电磁计算和仿真分析验证了上述研究的正确性。这对于开发现有雷达装备的极化测量处理能力、提升其抗干扰和目标识别能力具有一定的启发和指导意义。     

Improved Morphology and Efficiency of Polymer Solar Cells by Processing Donor–Acceptor Copolymer Additives

A novel wide‐bandgap conjugated polymer PBTA‐FPh based on benzodithiophene‐alt‐benzo[1,2,3]triazole as the main chain and a polar pentafluorothiophenyl (FPh) group in the side chain has been designed and synthesized. In comparison to the pristine polymer PBTA‐BO that consists of nonpolar alkyl side chains, the resulting PBTA‐FPh exhibits less pronounced aggregation while possessing analogous optical and electrochemical bandgaps. Contact angle measurements demonstrate that the surface energy can be enhanced by incorporating FPh moiety, leading to a better miscibility of PBTA‐BO with PC₇₁BM in the presence of a certain amount of PBTA‐FPh. The photoactive layer of PBTA‐BO:PC₇₁BM:PBTA‐FPh with weight ratio of 1:1.2:0.02% exhibits a percolated network with the fibrous features, as revealed by transmission electron microscopy measurements. Of particular interest is the significantly improved photovoltaic performances of polymer solar cell devices for which the power conversion efficiency is enhanced from 6.46% for the control device to 7.91% for device processed with PBTA‐FPh as the polymeric additive. These observations indicate that introducing donor–acceptor type of polymeric additive comprising of polar groups in the side chain can be a promising strategy for the fabrication of high‐performance polymer solar cells.