New multi-layer data correlation algorithm for multi-passive-sensor location system

Under the scenario of dense targets in clutter, a multi-layer optimal data correlation algorithm is proposed. This algorithm eliminates a large number of false location points from the assignment process by rough correlations before we calculate the correlation cost, so it avoids the operations for the target state estimate and the calculation of the correlation cost for the false correlation sets. In the meantime, with the elimination of these points in the rough correlation, the disturbance from the false correlations in the assignment process is decreased, so the data correlation accuracy is improved correspondingly. Complexity analyses of the new multi-layer optimal algorithm and the traditional optimal assignment algorithm are given. Simulation results show that the new algorithm is feasible and effective.

A CROSS-LAYER STRATEGY FOR COOPERATIVE DIVERSITY IN WIRELESS SENSOR NETWORKS

We investigate the problem of how to minimize the energy consumption in multi-hop Wireless Sensor Network (WSN),under the constraint of end-to-end reliability Quality of Seervice (QoS) requirement.Based on the investigation,we jointly consider the routing,relay selection and power allocation algorithm,and present a novel distributed cross-layer strategy using opportunistic relaying scheme for cooperative communication.The results show that under the same QoS requirement,the proposed cross-layer strategy performs better than other cross-layer cooperative communication algorithms in energy efficiency.We also investigated the impact of several parameters on the energy efficiency of the cooperative communication in WSNs,thus can be used to provide guidelines to decide when and how to apply cooperation for a given setup.

A 4-layer method of developing integrated sensor systems with LabVIEW

System integrity is important for fast and accurate measurement and control.LabVIEW is widely used in education and industry.Many LabVIEW codes are hard to be read and shown because of their 2D topology.In order to simplify the programming,a 4-layer model of developing sensor or measurement systems with LabVIEW is proposed in this paper.The purpose of this paper is to show the readers how to design simple,clear and strong automated systems with LabVIEW.Using a Sensirion SHT75 humidity sensor and an NI USB6008 DAQ board as an example,this paper describes the steps of developing a sensor system from the physical layer to application layer in detail.In layer 2,port selection and signal regulation are demonstrated.In layer 3,timing waveform analysis and synthesis,state diagram analysis,instruction set design,micro operation and fault tolerance designs are demonstrated.In layer 4,data visualization is covered with a vivid example.Programmers found it was hard to show readers their LabVIEW codes because many LabVIEW codes occupy several screens.A layer model simplifies the programming,so one is able to show a medium size LabVIEW code easily.

Cross-layer Enhancement to Multi-hop Routing in Sensor Networks: an Empirical Study

Lossy link is one of the unique characteristics in random-deployed sensor networks. We envision that robustness and reliability of routing cannot be ensured purely in network layer. Our idea is to enhance the performance of routing protocol by cross-layer interaction. We modified mint protocol, a routing protocol in TinyOS and proposed an enhanced version of mint called PA-mint. A transmission power control interface is added to network layer in PA-mint. When routing performance of the current network is not satisfied, PA-mint monotonically increases the transmission power via the interface we added. PA-mint is able to connect orphan nodes and robust to node mobility or key nodes failure. In the case that automatic request retransmission is employed, the number of retransmissions can be reduced by PA-mint. Results from experiments show that PA-mint increases the reliability and robustness of routing protocol by cross-layer interaction.

An Energy-Efficient Access Control Algorithm with Cross-Layer Optimization in Wireless Sensor Networks

This paper presents a wireless sensor network (WSN) access control algorithm designed to minimize WSN node energy consumption. Based on slotted ALOHA protocol, this algorithm incorporates the power control of physical layer, the transmitting probability of medium access control (MAC) layer, and the automatic repeat request (ARQ) of link layer. In this algorithm, a cross-layer optimization is preformed to minimizing the energy consuming per bit. Through theory deducing, the transmitting probability and transmitting power level is determined, and the relationship between energy consuming per bit and throughput per node is provided. Analytical results show that the cross-layer algorithm results in a significant energy savings relative to layered design subject to the same throughput per node, and the energy saving is extraordinary in the low throughput region.

Performance analysis of surface plasmon resonance sensor with high-order absentee layer

A surface plasmon resonance （SPR） sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit （FOM） depends on the refractive index of absentee layer. By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO2 （or AlAs） absentee layer is 1.059% （or 2.587%） higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors.

A Comparison of Link Layer Attacks on Wireless Sensor Networks

Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions such as cost, invisible deployment and many application domains, lead to small size and resource limited sensors [3]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional network security techniques are unusable on WSNs [3];This is due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. Therefore security is a vital requirement for these networks;but we have to design a proper security mechanism that attends to WSN’s constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs’ link layer attacks and a comparison of them. This work enables us to identify the purpose and capabilities of the attackers;furthermore, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paper discusses known approaches of security detection and defensive mechanisms against the link layer attacks;this would enable IT security managers to manage the link layer attacks of WSNs more effectively.

Toluene Sensing Properties of P4VP/Multi-Walled Carbon Nanotubes Multi-Layer Film Sensors

Abstract--Poly4-vinylphenol （P4VP）/multi-wan carbon nanotubes （MWNTs） multi-layer sensitive films were deposited on interdigitated electrodes by airbrush technology to detect toluene vapor at room temperature. The surface and section morphologies of the multi-layer films were observed by a scanning electron microscope （SEM）. It is found that the resistance of the sensor increases when it is exposed to toluene vapor and the response has a good linearity with the concentration of toluene. The results show that the P4VP/MWNTs three-layer film sensors have better sensing properties compared with the two-layer film sensors. The related sensing mechanism is studied in detail.

Cross Layered MAC Design for RF Energy Harvesting Sensor Network

The main research objective in wireless sensor networks (WSN) domain is to develop algorithms and protocols to ensure minimal energy consumption with maximum network lifetime. In this paper, we propose a novel design for energy harvesting sensor node and cross-layered MAC protocol using three adjacent layers (Physical, MAC and Network) to economize energy for WSN. The basic idea behind our protocol is to re-energize the neighboring nodes using the radio frequency (RF) energy transmitted by the active nodes. This can be achieved by designing new energy harvesting sensor node and redesigning the MAC protocol. The results show that the proposed cross layer CL_EHSN improves the life time of the WSN by 40%.

An Electrochemical Nitrite Sensor Based on a Multilayer Film of Polyoxometalate

In this work, we have developed an electrochemical sensor for nitrite detection, based on a polyoxometalate (POM) namely mono-lacunary keggin anion [SiW11O39]8﹣ cited as (SiW11). Electrochemical characterization of SiW11 shows two-step reduction processes, with formal potentials of ﹣0.5 V (I) and ﹣0.68 V (II). Oppositely charged polyelectrolyte (poly (allylamine hydrochloride) (PAH)) and (SiW11) were assembled alternately to modify glassy carbon electrode. The electrochemical behavior of the modified electrode was studied in detail using cyclic voltammetry (CV). The results showed that SiW11/PAH/GC electrode present good electrocatalytic activity for the reduction of nitrite. The sensor showed a dynamic range from 100 μM to 3.6 mMof nitrite and no interference from other classical anions. Experimental factors that affect electron-transfer rate in these films, such as pH effect and layers number, were systematically analyzed.

Cross Layer Design for Cooperative Transmission in Wireless Sensor Networks

Several protocols and schemes have been proposed to reduce energy consumption in Wireless Sensor Net-works (WSNs). In this paper we employ farcoopt, a cross layer design approach with the concept of coop-eration among the nodes with best farthest neighbor scheme to increase the Quality of Service (QoS), reduce energy consumption, increases performance and end-to-end throughput. We present cooperative transmission to connect previously disconnect parts of a network thus overcoming the separation problem of multi-hop network. We show that this approach improves connectivity over 50% compared to multi-hop approaches and reduces the number of nodes necessary to provide full coverage of an area up to 35%. Simulation results show that on increase of data rates i.e. packet the network life time increases in farcoopt as compared to tra-ditional multi hop approach. The result of this analysis is presented in this work.

用于压电传感器的层加层结构纳米纤维膜

通过聚丙烯腈(PAN)与改性木质素(CEHL-PTMG)接枝物进行共混,使用多层静电纺丝技术得到PAN|PAN/CEHL-PTMG|PAN层加层结构的纳米纤维膜,并制备一系列的薄膜。对制备的层加层结构纳米纤维膜进行表面形貌、构象、热性能、力学性能以及压电性能测试。实验结果表明:层加层结构使得薄膜的压电性能得到了大幅提高,PAN(11%,1 mL)|PAN/CEHL-PTMG(11%/2%,2 mL)|PAN(11%,1 mL)层加层结构纳米纤维膜的压电性能最为优异,输出电压和电流分别可达2.57 V、1468.0 nA;层加层结构薄膜的拉伸强度提高到了7.16 MPa,相较复合纳米纤维膜拉伸强度提高了7.51%,比纯PAN薄膜拉伸强度提高了52.67%;结构化后的薄膜的稳定性大幅提高,经过上千次的撞击仍能输出较好的电压;同时将其附于手指及手肘上,能更加明确地指示两者的运动,且在数值上出现较大的差距。

Characteristics Analysis of Chemical Concentration Sensor Based on Three-layer FBG

The three-layer structure model of the fiber Bragg grating is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments. A kind of simple structure, small size, good stability, high sensitivity chemical concentration sensor is obtained.

全纤维电容式传感器的结构设计及其性能

由于受柔性电容式传感器介电层弹性模量的限制,目前电容器的性能如灵敏度等难以达到应用要求,为提高传感器的传感性能,以聚吡咯复合蚕丝织物作为织物电极,羊毛纤维集合体作为介电层构建全纤维的电容式压力传感器,对电极的织物结构和纤维集合体高度进行优化分析;对传感器的电学及传感性能进行测试,并进行了应用探索。结果表明:面密度为69 g/m^(2)素绉缎聚吡咯复合织物方阻最小,为42Ω/□;纤维电容器以素绉缎聚吡咯复合织物作为电极,羊毛纤维集合体为介电层,且高度为1.4 cm时传感性能最优,在频率为10 kHz、电容最高为66 pF、压力为0~5 N范围内灵敏度最高为1.08 N^(-1)。该电容式传感器具有良好的稳定性,有望应用于肢体运动监测与公共场合安全监测中。

基于改进天鹰的三维室内多层结构定位算法

在面向一些大型商超、医院、教学楼等大规模室内多层结构定位中,针对多层WSN结构的非测距定位问题,提出一种基于改进天鹰的三维室内多层结构定位算法IAODV-HOP算法。首先,为节点划分3类通信半径以细化跳数,同时利用最小均方差和权重因子修正节点的平均跳距。其次,用IAO算法对未知节点坐标进行寻优,通过佳点集策略对种群初始化,解决天鹰算法因初始种群随机分布而导致的种群的质量和多样性难以保证的问题,并且在局部搜索中加入黄金正弦的搜索策略完善种群的位置更新方式,增强了算法的局部搜索能力。通过仿真实验,本文所提算法IAODV-HOP相较于传统3D-DV-Hop、PSO-3DDV-Hop、N3-3DDV-Hop以及N3-ACO-3DDV-Hop算法,归一化平均定位误差分别下降70.33%、62.67%、64%、53.67%,表现出更优的性能,具有更好的稳定性和更高的定位精度。

基于高温压力传感器的耐高温金属体系

从制约高温压力传感器发展的耐高温金属体系研究出发,采用钨/氮化钽/铂(W/TaN/Pt)作为金属布线的电传导层,开发出适用于500 ℃高温环境下稳定工作的金属薄膜,实现电信号稳定传输,有效避免相邻金属层之间相互扩散或合金导致的电性能失效。对500 ℃高温前后的压力传感器进行带电测试,并对非线性、迟滞性、灵敏度、重复性等8项指标做了测试对比,高温压力传感器性能稳定,各性能指标均满足使用要求,证明该金属体系的可行性。

A Contention-Based MAC and Routing Protocol for Wireless Sensor Network

Advance development of wireless technologies and micro-sensor systems have enabled Wireless Sensor Network (WSN) to emerge as a leading solution in many crucial sensor-based applications. WSN deploys numerous resource-constrained sensor nodes which have limited power supply, memory and computation capability in a harsh environment. Inefficient routing strategy results in degraded network performance in terms of reliability, latency and energy efficiency. In this paper, a cross-layer design, Contention-based MAC and Routing protocol is proposed, termed Contention/SNIR-Based Forwarding (CSBF) protocol. CSBF utilizes the geographical information of sensor nodes to effectively guide the routing direction towards destination node, thereby enhancing reliability. Furthermore, Signal-to-Noise-plus-Interference Ratio (SNIR) metric is used as a routing parameter to guarantee high quality link for data transmission. A Contention-Winner Relay scheme is utilized to reduce the delays caused by the contention procedure. Energy efficiency is also improved by introducing sleep mode technique in CSBF. The simulation work is carried out via OMNeT++ network simulator. The performance of CSBF is compared with other existing routing protocols such as AODV and DSDV in terms of packet delivery ratio (PDR), average end-to-end (ETE) delay and energy consumption per packet. Simulation results highlight that CSBF outperforms AODV and DSDV protocols in respect of PDR and energy efficiency. CSBF also has the most consistent overall network performance.

柔性层状石墨烯感应元件制备及其力敏特性

为了弥补现有传感器在混凝土非连续变形监测上的不足,采用特殊构型法,以还原氧化石墨烯-纳米纤维素(RGO-CNF)为传感层、聚二甲基硅氧烷(PDMS)为基层,设计和制备了PDMS/RGO-CNF/PDMS层状感应元件,对其力学、电学和力敏性能进行测试和分析.结果表明,CNF能够有效地协助RGO在异丙醇中均匀分散,经化学溶胀和孔隙填充构建的传感层与基底层紧密结合,能够承受超过100%的拉伸应变.感应元件经过约10次循环拉伸后,应变电阻响应达到稳定状态,表现出良好的可回复性和可重复性.在0~10%应变下,感应元件的电阻变化率近似呈线性变化,灵敏系数可达15,随应变继续增大,电阻变化率呈指数型增长.应变电阻响应强度随应变速率的增大而提高,利用建立的考虑应变率效应的应变电阻响应模型,能够较好地预测感应元件的力敏行为.

基于取向纤维基底和图案化双相金属层的高灵敏应变传感器

为了提高液态金属基应变传感器的灵敏度,研究了一种高灵敏度、可拉伸的应变传感器,该传感器由取向的静电纺热塑性聚氨酯纤维基底和图案化双相金属传感层构成。以液态金属Galinstan为“岛”,固体金属银为“海”,构建了图案化双相金属传感层。银“海”可阻止连续的液态金属导电路径的形成,基于银导电区域的裂纹扩展机制,传感器的灵敏度显著提高。此外,纤维取向(水平或垂直)削弱了在受力时纤维的重新排列,增强了传感层的变形。结果表明,对于单一液态金属层或Ag层组成的传感器,基底纤维垂直取向与随机排列比较,灵敏度分别提高1.09倍和33.19倍。最终制成的基于垂直取向纤维基底和图案化双相金属层的应变传感器具有超高的灵敏度(灵敏度系数高达952.20)和宽传感范围(高达59.33%)。这种设计有望在可穿戴设备中显示良好的应用潜力。

动态层簇式无线传感网络信息加密算法

与传统的无线网络基于某种确定的网络拓扑结构组织不同,动态层簇式无线传感网络(Dynamic Layer Clustered Wireless Sensor Networks,DLCN)则是通过动态层次化的方式进行组织,导致DLCN在层次簇、簇首节点选取等诸多细节,实现较为复杂,其信息加密复杂度增加,安全性和平衡性问题一直是一个难点。提出针对动态层簇式无线传感网络的信息加密算法。分析动态层簇式无线传感网络结构,计算网络节点权重跳数以及传输时延,选取最优簇首,通过Logistic混沌映射对混沌序列展开计算,结合Merlay状态机的迁移传输,输出子密钥,实现了传感信息的加密。仿真结果表明:所提算法在DLCN数据加密过程中的密文位数始终在60左右、平均密钥扩展用时在2.5 ms以下、且二值比数值更接近于1,具备较高的安全性和平衡性。