酞菁钯-聚苯胺修饰声表面波传感器及含磷毒气的检测

针对含磷毒气快速检测问题,以自制的杂化酞菁钯.聚苯胺为敏感膜材料,设计了一种双信道声表面波(SAW)传感器.阐述了传感器的基本原理,推导出以有机膜作为信道中间介质时,差频输出△f由物理化学吸附两种机制叠加的数学模型.依据声波振荡条件,设计了146±5MHz振荡频率的信号采集电路;以钽酸锂晶体为压电基片,通过MEMS微加工技术形成叉指电极对和加热膜;以真空镀膜工艺将敏感膜材料成膜,修饰在SAW信道中间区域构成SAW传感器.测试结果表明:最优气敏性时的材料配比为PdPc0.35PANI0.65;芯片加热60～80℃可提高性能,响应时间≤30s;输出与测试气体浓度与数学模型一致,为线性变化率-110kHz(mg/m3)的N型线性关系;抗汽油、CO2等气体干扰;80天稳定性考核,△f≤±0.1kHz,满足实际使用要求.     

基于射频识别的无线传感网节点设计研究

为了解决无线传感网通常运行在人不能或不便接近的环境,能源无法替代的问题,该设计采用了单片机MSP430F2370芯片和少量外围电路等来构成完整测量系统。由于其充分利用了单片机内部资源,使系统硬、软件设计达到了最小化,具有识别可靠性高、抗干扰能力强、成本低廉和体积小巧等特点。它可以识别ISO15693,ISO14443A,ISO14443B等多种协议标准的电子标签。在今后的门禁系统、生产线检测、自动收费系统、超市物流等方面有很大的应用前景。     

一种多媒体传感器网络低能耗分簇协议

多媒体传感器网络面临的主要挑战是在能量受限的情况下传输大量数据。在经典分簇协议LEACH的基础上,提出一种考虑数据量的多媒体传感器网络低能耗分簇协议。在簇头选举阶段,选择剩余能量多和数据量大的节点作为簇头;在成簇阶段,同时考虑节点到簇头的通信距离和节点的数据量让节点加入簇。仿真结果表明,提出的协议能有效提高网络的生命周期。     

Pixel‐Structured Scintillator with Polymeric Microstructures for X‐Ray Image Sensors

We introduce a pixel‐structured scintillator realized on a flexible polymeric substrate and demonstrate its feasibility as an X‐ray converter when it is coupled to photosensitive elements. The sample was prepared by filling Gd₂O₂S:Tb scintillation material into a square‐pore‐shape cavity array fabricated with polyethylene. For comparison, a sample with the conventional continuous geometry was also prepared. Although the pixelated geometry showed X‐ray sensitivity of about 58% compared with the conventional geometry, the resolving power was improved by about 70% above a spatial frequency of 3 mm^?1. The spatial frequency at 10% of the modulation‐transfer function was about 6 mm^?1.     

无线传感器网络关键技术及其研究难点

本文在简要介绍无线传感器网络特点的基础上,给出了无线传感器网络的体系结构,在此体系结构下,系统地阐述了无线传感器网络的研究现状,并指出了尚存在的难点和可能的研究方向.     

基于遗传聚类的无线传感器负载均衡路由算法

通常的无线传感器分簇网络存在节点负载不均衡的问题。为均衡各节点能量消耗,延长网络生存周期,将K均值算法与遗传算法相结合,提出一种负载均衡的无线传感器网络路由算法,算法利用遗传算法的全局寻优能力以克服传统K均值算法的局部性和对初始中心的敏感性,实现了传感器网络节点自适应成簇与各节点负载均衡。仿真实验表明,该算法显著延长了网络寿命,相对于其他分簇路由算法,其网络生存时间延长了约43%。     

Anchor‐free distance estimation: A new approach to distance estimation for multihop ad hoc wireless networks

In ad hoc wireless networks, devices that normally cannot directly communicate route their messages through intermediate nodes. The number of those nodes is called hop count, a useful metric in estimating the distance between 2 nodes. Current methods usually depend on special nodes, called anchors, that need accurate localization information, in order to calculate an estimate for the average distance traversed per hop. The drawback of this approach is that anchor nodes increase the overall cost and complexity of the system. To address this problem, this letter proposes a novel, anchor node–free algorithm that can achieve a useful estimate for actual distance between 2 nodes, by analytically finding an estimate for the average maximum distance traveled per hop and multiplying with the hop count. The only requirement is the a priori knowledge of the networks' node density and the node range. The performance of our method is compared with a recent anchor node–based method and is shown to yield similar location estimation accuracy, despite the fact that it does not use anchor nodes.     

红外探测器组网预警技术研究

通过对红外探测器组网的可行性进行分析和对其优化配置,数据接入与融合以及预警系统评估技术进行研究,为发展预警探测系统的集成实验提供了技术支撑,并为提升我国红外探测器组网技术水平提出了一些新的思路.     

A 1.65μm three-section distributed Bragg reflector （DBR） laser for CH4 gas sensors

A 1.65-μm three-section distributed Bragg reflector(DBR) laser for CH4 gas sensors is reported.The DBR laser has a wide tunable range covering the R3 and R4 methane absorption line manifolds.The wavelength tunability properties,temperature stability and laser linewidth are characterized and analyzed.Several advantages were demonstrated compared with traditional DFB lasers in harmonic detection.     

电磁矢量传感器阵列相干信号源波达方向和极化参数的同时估计:空间平滑方法

研究如何利用电磁矢量传感器阵列中隐含的冗余空域信息解决多个相干极化信号源的二维波达方向(DOA)和极化参数的同时估计问题。基于整个阵列中所隐含的多个空域旋转不变结构,将组成阵列的单个或多个电磁矢量传感器单元看作一个无模糊子阵,利用空间平滑方法对阵列数据进行预处理,以恢复信号协方差矩阵的秩特性。在此基础上,利用多信号分类方法(MUSIC)和旋转不变参数估计方法(ESPRIT)完成多个相干极化信号源的二维 DOA 和极化参数的同时估计。文中还讨论了成功进行信号解相干的必要条件,并通过计算机仿真验证和比较了所给方法的有效性及其辨识能力。