Channel Assignment Method Using Parallel Tabu Search Based on Graph Theory in Wireless Sensor Networks

Wireless sensor networks are suffering from serious frequency interference.In this paper,we propose a channel assignment algorithm based on graph theory in wireless sensor networks.We first model the conflict infection graph for channel assignment with the goal of global optimization minimizing the total interferences in wireless sensor networks.The channel assignment problem is equivalent to the generalized graph-coloring problem which is a NP-complete problem.We further present a meta-heuristic Wireless Sensor Network Parallel Tabu Search(WSN-PTS) algorithm,which can optimize global networks with small numbers of iterations.The results from a simulation experiment reveal that the novel algorithm can effectively solve the channel assignment problem.

A multi-channel chemical sensor and its application in detecting hydrothermal vents

There are well-established chemical and turbidity anomalies in the plumes occurring vicinity of hydrothermal vents, which are used to indicate their existence and locations. We here develop a small, accurate multi-channel chemical sensor to detect such anomalies which can be used in deep-sea at depths of more than 4 000 m. The design allowed five all-solid-state electrodes to be mounted on it and each (apart from one reference electrode) could be changed according to chemicals to be measured. Two experiments were conducted using the chemical sensors. The first was a shallow-sea trial which included sample measurements and in situ monitoring. pH, Eh, CO3^2- and SO4^2- electrodes were utilized to demonstrate that the chemical sensor was accurate and stable outside the laboratory. In the second experiment, the chemical sensor was integrated with pH, Eh, CO3^2- and H2S electrodes, and was used in 29 scans of the seabed along the Southwest Indian Ridge (SWIR) to detect hydrothermal vents, from which 27 sets of valid data were obtained. Hydrothermal vents were identified by analyzing the chemical anomalies, the primary judging criteria were decreasing voltages of Eh and H2S, matched by increasing voltages of pH and CO3^2- . We proposed that simultaneous detection of changes in these parameters will indicate a hydrothermal vent. Amongst the 27 valid sets of data, five potential hydrothermal vents were targeted using the proposed method. We suggest that our sensors could be widely employed by marine scientists.

Power control and channel allocation optimization game algorithm with low energy consumption for wireless sensor network

In a wireless sensor network （WSN）, the energy of nodes is limited and cannot be charged. Hence, it is necessary to reduce energy consumption. Both the transmission power of nodes and the interference among nodes influence energy consumption. In this paper, we design a power control and channel allocation game model with low energy consumption （PCCAGM）. This model contains transmission power, node interference, and residual energy. Besides, the interaction between power and channel is considered. The Nash equilibrium has been proved to exist. Based on this model, a power control and channel allocation optimization algorithm with low energy consumption （PCCAA） is proposed. Theoretical analysis shows that PCCAA can converge to the Pareto Optimal. Simulation results demonstrate that this algorithm can reduce transmission power and interference effectively. Therefore, this algorithm can reduce energy consumption and prolong the network lifetime.

基于Multi-Radio Multi-Channel传感器网络无冲突信道分配算法的研究

为降低通信冲突和信道干扰,对Mult-i Radio Mult-i Channel传感器网络无冲突信道进行研究,结果证实在网络通信半径大于3倍的网络最大功率通信半径的前提下,Sensor节点规模满足2倍网络功率级数加1的环境下,网络无冲突信道分配的信道数达到网络信道冲突图的最大值。文章通过对无冲突信道算法的运用,最终证实其可以有效地提高传感器网络的工作效率,大幅度提升网络的吞吐量。

Priority-Based Hybrid MAC for Energy Efficiency in Wireless Sensor Networks

This paper introduces I-MAC, a new medium access control protocol for wireless sensor networks. I-MAC targets at improving both channel utilization and energy efficiency while taking into account traffic load for each sensor node according to its role in the network. I-MAC reaches its objectives through prioritized and adaptive access to the channel. I-MAC performances obtained through simulations for different network topologies, scenarios and traffic loads show significant improvements in energy efficiency, channel utilization, loss ratio and delay compared to existing protocols.

无线地下传感网信道传播实验虚拟仿真与可视化教学

为帮助学生更好地理解和掌握无线地下传感网信道传播特性,推导并建立一个融合土壤特性参数的改进地下无线信道传播模型,在该模型基础上开发无线地下传感网实验虚拟仿真系统。该仿真系统不仅解决实验环境受限、难以开展实验教学的问题,且具有易于理解和操作的特点,仿真结果以图形化和可视化的形式呈现。通过此系统,学生可直观地观察和比较不同参数影响下地下无线信道传播变化情况,深入理解地下无线信道的复杂传播特性,提高学生的学习效率,激发学生的学习兴趣,促进学生学习的主动性和积极性。

On Energy-Efficient Time Synchronization for Wireless Sensors under Large-Scale and Small-Scale Fading Effects

In this work, the existing trade-off between time synchronization quality and energy is studied for both large-scale and small-scale fading wireless channels. We analyze the clock offset estimation problem using one-way, two-way and N-way message exchange mechanisms affected by Gaussian and exponentially distributed impairments. Our main contribution is a general relationship between the total energy required for synchronizing a wireless sensor network and the clock offset estimation error by means of the transmit power, number of transmitted messages and average message delay, deriving the energy optimal lower bound as a function of the time synchronization quality and the number of hops in a multi-hop network.

AN ENERGY-EFFICIENT OPTIMIZATION DEPLOYMENT SCHEME FOR WIRELESS SENSOR NETWORKS

Most of the current deployment schemes for Wireless Sensor Networks (WSNs) do not take the network coverage and connectivity features into account, as well as the energy consumption. This paper introduces topology control into the optimization deployment scheme, establishes the mathe-matical model with the minimum sum of the sensing radius of each sensors, and uses the genetic al-gorithm to solve the model to get the optimal coverage solution. In the optimal coverage deployment, the communication and channel allocation are further studied. Then the energy consumption model of the coverage scheme is built to analyze the performance of the scheme. Finally, the scheme is simulated through the network simulator NS-2. The results show the scheme can not only save 36% energy av-eragely, but also achieve 99.8% coverage rate under the condition of 45 sensors being deployed after 80 iterations. Besides, the scheme can reduce the five times interference among channels.

Evaluation of Network Stack Optimization Techniques for Wireless Sensor Networks

We present a network stack implementation for a wireless sensor platform based on a byte-level radio. The network stack provides error-correction code, multi-channel capability and reliable communication for a high packet reception rate as well as a basic packet-level communication interface. In outdoor tests, the packet reception rate is close to 100% within 800 ft and is reasonably good up to 1100 ft. This is made possible by using error correction code and a reliable transport layer. Our implementation also allows us to choose a fre-quency among multiple channels. By using multiple frequencies as well as a reliable transport layer, we can achieve a high packet reception rate by paying additional retransmission time when collisions increase with additional sensor nodes.

On the Trade-off between Power Consumption and Time Synchronization Quality for Moving Targets under Large-Scale Fading Effects in Wireless Sensor Networks

In this work we find a lower bound on the energy required for synchronizing moving sensor nodes in a Wireless Sensor Network (WSN) affected by large-scale fading, based on clock estimation techniques. The energy required for synchronizing a WSN within a desired estimation error level is specified by both the transmit power and the required number of messages. In this paper we extend our previous work introducing nodes’ movement and the average message delay in the total energy, including a comprehensive analysis on how the distance between nodes impacts on the energy and synchronization quality trade-off under large-scale fading effects.

基于LabVIEW的风电主轴承螺栓预紧力监测系统

针对大型风电主轴承容易产生轴向振动故障问题,基于端盖螺栓预紧力的变化特性,本文拟开发一款螺栓预紧力采集监测系统。该系统采用一种嵌入分布式的垫片压力传感器测量方法,以DH5902N数据采集卡和计算机为硬件,实现螺栓预紧力数据采集和分析。构建应用于风电机主轴承的压力传感器检测模型,通过建立基于传感器数据测量的螺栓预紧力校正算法,实现风电机主轴承轴向受力检测。选用LabVIEW作为软件开发平台,实现多通道数据采集显示与灯光报警等功能,最终实现对风电主轴承的受力状态监测。

多通道钢丝绳的漏磁检测信号融合方法

分析了现有钢丝绳漏磁检测系统中存在的损伤信号幅值较小、前端多个磁敏元件处理方式较为简单等问题,提出了一种钢丝绳漏磁检测系统中的多通道信号融合方法。首先从磁敏元件阵列的角度出发,提出了多种磁敏元件阵列方式;其次从信号处理模拟电路的角度出发,设计了多通道信号融合硬件电路;最后,针对钢丝绳进行了实际测试,验证了此方法的可行性。

多通道电磁阀电流检测系统设计

为了在线测量应用于石油化工行业的电磁阀驱动电源电流,对石油化工行业的电磁阀驱动电源电流的在线检测进行了研究。设计了一种多通道电磁阀电流检测系统。电流检测系统以STM32为核心控制模块、以电流传感器为测量传感器。硬件部分包括数据采集模块、数据存储模块、数据传输模块等。系统支持多通道电流信号的在线检测、在线设定电流异常阈值,可实时动态地将采集到的电流数据和电流判断结果传送到人机界面(HMI)软件。通过电流模拟试验,验证了测量系统的可行性。测试结果表明,该系统能够满足多路电磁阀电流的在线检测需求,且测试过程对被测设备无影响。该系统测量精度高、实现简单、便于安装,也可应用于其他行业的电流检测。

Lifetime Enhancement of Cluster Based Wireless Sensor Network through Energy Efficient MAC Protocol

The efficient use of energy is an important performance metric to extend the lifetime of wireless sensor networks. Since major energy consumption of node is due to its transceiver, the design of MAC protocol plays a vital role in sensor network design. In cluster based sensor networks, due to the different functions of member node and cluster head node, the usage of common MAC protocol results increased energy consumption. To overcome this problem, a novel energy efficient hybrid MAC protocol (EEHMAC) for cluster based wireless sensor networks is proposed in this paper. The proposed EEHMAC protocol uses E-TDMA (Energy efficient TDMA) for intra-cluster communication and FDMA (Frequency Division Multiple Access) for inter-cluster communication. IDS (Iterative Deepening Search) based Scheduling algorithm is used for assigning time slot and frequency slot to nodes. Nodes in EEHMAC follow the periodic duty cycle, which reduces the idle listening, and overhearing problems. Simulation results reveal that an average of 18% energy saving is achieved compared to LEACH (Low Energy Adaptive Clustered Hierarchy) protocol and 10% energy is saved in comparison with GH-MAC (Graph theory based Hybrid MAC) protocol. It is evident that delay of EEHMAC is reduced by 17% and throughput is increased by 15% under all traffic conditions. These results demonstrate that EEHMAC performs better than existing MAC protocols in terms of energy efficiency, delay and throughput.

无线传感器网络的多信道信息融合方法设计

在无线传感器网络组成的物联网中,受并行通信的干扰,导致多信道信息融合效果差、时延高、信息传送能耗大。为此,提出了针对物联网中无线传感器网络的多信道信息融合方法。通过树型拓扑结构合理分配物联网中传感路由节点信道,抑制并行传感通信的干扰。根据信息熵理论,获取各传感信道信息之间的距离差,采用欧氏距离得出各信息单元的距离熵,进行归一化处理,计算出各传感信息单元属性与融合的权重,按照线性加权算法融合各部分的信息,完成多信道信息融合。仿真结果表明:所提方法的多信道信息融合时延和信息传送能耗始终低于0.69 s和59 J,证明所提方法在传感网络多信道信息融合的效果较好,能够有效降低传感信息融合时延,减小传感信息传送能耗。

基于光电传感的小动物主动运动行为评价及运动动机的神经机制研究

目的:构建小鼠主动运动行为量化评价系统,为运动与主动健康机制研究、慢病运动干预搭建平台,并通过在体实时采集主动运动不同阶段的脑电信号,探讨运动动机的神经调控机制。方法:1)构建基于光电传感的主动运动多模态系统(voluntary exercise multimodal system, VEMS),包括基于霍尔传感电信号的运动行为采集系统和基于机器视觉的运动轨迹分析系统;2)以C57BL/6小鼠为研究对象,应用VEMS系统记录小鼠主动运动行为并进行量化分析;3)结合在体多通道电生理记录技术采集小鼠主动运动不同阶段中脑腹侧被盖区(ventral tegmental area,VTA)神经元电活动,分析运动动机的神经编码特征。结果:1)VEMS系统可实现小鼠运动节律、运动距离、运动圈数、运动速度、运动时长和运动频次等行为数据的采集及量化分析;2)小鼠日运动时间主要集中在19:00—次日7:00,表现出较强的夜行节律,日运动距离最多可达15 km。每小时最大运动量出现在夜间1:00—2:00,运动圈数为0圈/10 min~170圈/10 min,每小时最大运动频次为23次,速度区间分布在0~12 m/min;3)在运动准备期、运动期及运动停止期,VTA神经元表现出不同的局部场单位(local field potentials,LFPs)特征信号,与运动停止期相比,运动准备期和运动期LFPs信号的θ频段(4~8 Hz)功率谱密度显著升高(P<0.001),且振荡显著增强(P<0.001);4)研究记录到59个对运动特异性响应的多巴胺(dopamine,DA)神经元,平均放电频率为(5.01±0.89) Hz,其中21%的DA神经元(Type-Ⅰ)在运动准备期高频放电,42%的DA神经元(Type-Ⅱ)在运动期有较强放电活动,37%(Type-Ⅲ)在运动停止后放电活动增多(P<0.001)。结论:1)本研究首次创建了VEMS系统,该系统能够对小鼠的主动运动行为进行多维度采集与量化评价分析,不仅为后期精准运动处方制定提供参考模型,还为运动神经科学的研究提供在体实时脑信号采集平台;2)小鼠主动运动行为受到VTA神经元特异性调节,DA神经元在运动准备期、运动期、运动停止期发挥不同作用。Type-Ⅰ和Type-Ⅲ神经元分别在运动准备期和运动停止期双向正反编码,即Type-Ⅰ神经元对奖励性正面信号表现出放电增强,而Type-Ⅲ神经元在运动停止时表现出特异放电。

基于柔性薄膜的多参数高灵敏汗液传感器研究

提出一种全新的基于柔性薄膜材料的高灵敏度、多参数汗液成分分析传感器,对敏感材料的特性及高灵敏度捕获机理进行了研究分析,设计了一种抗干扰信号采集电路,最终完成传感器样品制备,并搭建测试环境,对其关键性能指标进行了测试。结果表明,汗液传感器可实现对钾离子、钠离子、葡萄糖3种汗液成分的实时监测,在检测灵敏度和抗干扰性能上达到较好水平,与传统的检测仪器或单参数汗液传感器检测方法相比,在实用性上有很大的提升。

基于比色法和表面增强拉曼光谱双传感系统检测水中的芘

设计了一种基于AgNPs-AuNPs的核-卫星纳米结构检测水样中多环芳烃芘的比色和SERS双通道传感系统。首先将单巯基β-环糊精修饰到纳米金颗粒和纳米银颗粒的表面。受益于氧化态的四甲基联苯胺的触发,当体系中存在多环芳烃芘时,纳米颗粒会自组装形成AgNPs-pyrene-AuNPs的核-卫星结构。芘分子在其中充当分子桥的作用,拉近纳米粒子距离,使得纳米粒子发生一定的聚集。所以芘分子的个数直接影响AgNPs-pyrene-AuNPs的核-卫星结构数量,使溶液颜色发生变化,能够通过目测法建立溶液颜色与芘浓度的关系;组装形成的的核-卫星结构具有非常丰富的“热点”而表现出较强的表面增强拉曼光谱(SERS)活性,可通过SERS方法实现芘分子的高灵敏高特异检测。此结构可通过比色法和SERS方法实现水中芘的高灵敏高特异性检测。该方法可以在25 min内快速完成微量芘的检测,比色法对芘的检出限为3.4μmol·L^(-1), SERS法的检出限为0.42μmol·L^(-1)。根据上述原理,基于AgNPs-PAHs-AuNPs核-卫星结构的SERS传感器可用来检测水样中的多种多环芳烃。这一双通道传感系统提供了一种检测水样中多环芳烃芘的新方法,并为开发多路复用的传感系统提供了新的思路。

半航空电磁接收系统的设计与应用

利用半航空电磁法进行勘探时,半航空电磁接收系统中线圈传感器获取的电压信号很小且易受噪声等因素干扰,无法直接采样和分析。针对上述问题,设计了一套新型的低噪声半航空电磁接收系统。该系统以双通道匹配晶体管MAT03、MAT12和低噪声放大器AD8429为核心设计了低噪声放大电路,以运算放大器NE5532为核心设计了五阶低通滤波电路。通过仿真验证了设计电路功能的可行性,并对其进行了性能测试和野外试验。测试和试验结果表明:所设计的放大电路增益可调且噪声低于市面上的放大器,低通滤波电路抑制高频干扰效果良好。

基于LoRa的多传感器低功耗数据采集方法

针对LoRa多传感器低功耗采集中同信道传感节点无效唤醒的问题,提出一种基于空中唤醒策略与信道切换机制相结合的低功耗采集方法。通过将LoRa通信链路划分为多个通信信道,不同信道分时切换复用,实现多传感节点的分组通信,避免从传感节点的无效唤醒,在有限信道容量下最大限度地降低从节点的通信功耗;并制定了LoRa局域网传感器通信指令协议,实现了多传感器的低功耗主动轮询采集、定点调试与预警上报。实验结果证明了所提方法的有效性。