Maximizing lifetime in wireless sensor networks with multiple sensor families

Wireless sensor networks are generally composed of a large number of hardware devices of the same type, deployed over a region of interest in order to perform a monitoring activity on a set of target points. Nowadays, several different types of sensor devices exist, which are able to monitor different aspects of the region of interest (including sound, vibrations, proximity, chemical contaminants, among others) and may be deployed together in a heterogeneous network. In this work, we face the problem of maximizing the amount of time during which such a network can remain operational, while maintaining at all times a minimum coverage guarantee for all the different sensor types. Some global regularity conditions in order to guarantee a fair level of coverage for each sensor type to each target are also taken into account in a second variant of the proposed problem. For both problem variants we developed an exact approach, which is based on a column generation algorithm whose subproblem is either solved heuristically by means of a genetic algorithm or optimally by an appropriate ILP formulation. In our computational tests the proposed genetic algorithm is shown to be able to dramatically speed up the procedure, enabling the resolution of large-scale instances within reasonable computational times.     

一种矿用二氧化氮传感器的检测方法

矿用二氧化氮传感器是煤矿常用的气体检测仪表，针对煤矿需求开发的矿用二氧化氮传感器，需要满足煤矿矿用产品要求。文章提出一种矿用二氧化氮传感器检测方法，说明矿用二氧化氮传感器需要满足的技术参数，供实验室检测人员借鉴，也为设计制造矿用二氧化氮传感器提供了参考。     

Influences of magnetic fields on current–voltage characteristics of gold-DNA-gold structure with variable gaps

Achieving highly sensitive magnetic sensors by means of Metal-DNA-Metal (MDM) structure is a key issue. DNA, being a genetic information carrier in living cells reveals tunable semiconducting response in the presence of external electric and magnetic fields, which is promising for molecular electronics. The influence of magnetic fields up to 1200 mT on the current–voltage (I–V) behavior of Gold-DNA-Gold (GDG) structure having variable gap sizes from 20–50 μm are reported in this work. These structures were fabricated using UV lithography, DC magnetron sputtering and thermal evaporation techniques. DNA strands were extracted from Boesenbergia rotunda plant via standard protocol. The acquired I–V characteristics display the semiconducting diode nature of DNA in GDG structures. The potential barrier for all the structures exhibit an increasing trend with the increase of externally imposed magnetic field irrespective of variable gap sizes. Furthermore, the potential barrier in GDG junction at higher magnetic field strengths (>1000 mT) is found to be considerably enhanced. This enhancement in the junction barrier height at elevated magnetic fields is attributed to the reduction of carrier mobility and augmentation of resistance. The achieved admirable features of magnetic sensitivity suggest the viability of using these GDG sandwiches as a prospective magnetic sensor.     

浅谈D11T推土机履带链实施翻套检修工艺的必要性

文章从黑岱沟露天煤矿及哈尔乌素露天煤矿D11T推土机履带链的结构入手，对其常见故障的失效形式进行了详细分析和论述，并通过对160条履带链的使用寿命进行采样统计分析，阐述了在5500h进行履带链翻套检修的必要性，以及详细的检修工艺措施。为延长矿用推土机履带链的使用时间提供了可参考的资料，有一定的借鉴价值。     

Highly stretchable self-sensing actuator based on conductive photothermally-responsive hydrogel

Soft robots built with active soft materials have been increasingly attractive. Despite tremendous efforts in soft sensors and actuators, it remains extremely challenging to construct intelligent soft materials that simultaneously actuate and sense their own motions, resembling living organisms’ neuromuscular behaviors. This work presents a soft robotic strategy that couples actuation and strain-sensing into a single homogeneous material, composed of an interpenetrating double-network of a nanostructured thermo-responsive hydrogel poly(N-isopropylacrylamide) (PNIPAAm) and a light-absorbing, electrically conductive polymer polypyrrole (PPy). This design grants the material both photo/thermal-responsiveness and piezoresistive-responsiveness, enabling remotely-triggered actuation and local strain-sensing. This self-sensing actuating soft material demonstrated ultra-high stretchability (210%) and large volume shrinkage (70%) rapidly upon irradiation or heating (13%/°C, 6-time faster than conventional PNIPAAm). The significant deswelling of the hydrogel network induces densification of percolation in the PPy network, leading to a drastic conductivity change upon locomotion with a gauge factor of 1.0. The material demonstrated a variety of precise and remotely-driven photo-responsive locomotion such as signal-tracking, bending, weightlifting, object grasping and transporting, while simultaneously monitoring these motions itself via real-time resistance change. The multifunctional sensory actuatable materials may lead to the next-generation soft robots of higher levels of autonomy and complexity with self-diagnostic feedback control.     

基于链路可靠性的两跳QoS路由

针对工业无线传感器网络对路由协议的QoS要求，研究了一种基于链路可靠性的两跳QoS路由（Link-Reliability Based Two-Hop Routing for QoS Guarantee in Industrial Wireless Sensor Networks， LRTHQR）.采用两跳速度策略和数据优先级调度策略提高实时性，采用改进的信任评估模型以选择可信路径进行路由，采用基于接收功率的链接概率和数据包重传次数作为衡量链路可靠性的指标，同时采用能够综合考虑节点剩余能量和转发能耗的转发策略，以改善网络寿命.仿真结果显示：与未考虑链路可靠性的NCSRT （NodeCredible Security Routing for IWSN Based on THTR）算法相比， LRTHQR算法在丢包率、时延以及包平均能耗方面有着明显优势；与同样侧重QoS要求的LRTHR （Link-Reliability based Two-Hop Routing）算法相比， LRTHQR算法在截止期错失率、路由开销以及包平均能耗方面有着显著提升.     

网络匿名扫描系统设计及优化

针对网络扫描工具在进行扫描时面临的溯源问题，提出了一种匿名网络扫描系统。首先将匿名系统与网络扫描工具结合以实现匿名扫描；然后在现有匿名系统的基础上实现了该系统的本地私有化；接着通过流量分析发现，Nmap的多进程扫描因为代理链的原因会变成单进程扫描而导致其扫描扫描性能较低；最后提出了一种基于多Namp进程并发的性能优化方案，将总体扫描任务分割为多个扫描任务，并分配给多个单独的Nmap进程并行运行。实验结果表明，该性能优化方案的扫描时延接近正常扫描情况下的时延，达到了提高匿名扫描系统性能的目的。因此，该优化后的网络匿名扫描系统在阻碍溯源的同时提升了扫描效率。     

基于MF-R和AWS密钥管理机制的物联网健康监测大数据分析系统

带有传感器的可穿戴式医疗设备不断生成大量数据，由于数据的复杂性，难以通过处理和分析大数据来找到有价值的决策信息。为了解决这个问题，提出了一种新的物联网体系结构，用于存储和处理医疗应用的可扩展传感器数据（大数据）。所提出的架构主要由两个子架构组成：Meta Fog重定向（MF-R）架构和AWS密钥管理机制。MF-R架构使用Apache Pig和Apache HBase等大数据技术来收集和存储不同传感器设备生成的传感器数据，并利用卡尔曼滤波消除噪声。AWS密钥管理机制使用密钥管理方案，目的是保护云中的数据，防止未经授权的访问。当数据存储在云中时，所提出的系统能够使用随机梯度下降算法和逻辑回归来开发心脏病的预测模型。仿真实验表明，和其他几种算法相比，提出的算法具有更小的误差，且在吞吐量、准确度等方面具有一定的优越性。     

基于概率感知模型的多节点联合网络覆盖算法

针对传感网在对关注目标节点进行覆盖过程中出现的非连续性覆盖，将会产生覆盖盲区以及大量冗余数据迫使通信链路出现瓶颈现象，提出了一种基于概率感知模型的多节点联合覆盖算法（Multi-Node Joint Network Coverage Algorithm，MNJC）。该算法借助于概率相关知识，给出了多节点联合时覆盖质量期望值计算方法，以减少覆盖盲区的产生，提高了多节点联合网络覆盖率；利用节点动态转换机制对节点部署进行重新优化，抵制了网络能量的快速消耗，延长网络生存周期；该算法与其他三种算法覆盖率、生存周期以及节点存活数量等方面进行了比对实验，其性能指标平均提升了18.11%，15.57%和8.26%，从而验证该算法的有效性和实效性。     

基于3D打印技术制造柔性传感器研究进展

与传统的涂覆、沉积等加工手段相比，使用3D打印技术可制造复杂立体功能结构的传感器，将3D打印与柔性传感技术结合可以促进未来生物医疗、人工智能等领域的发展。本文介绍了国内外基于3D打印技术制造柔性传感器的最新进展，其中包括聚酰亚胺等多种基底材料、纳米金属等多种打印传感材料；按照熔融沉积、黏弹性墨水沉积、粉末烧结熔化、还原光聚合和材料喷射的制造原理分别阐述了多种传感器的材料选择、成型特点，并对制造方法进行总结分析。虽然3D打印制造柔性传感器件存在着缺乏行业标准及多种类打印材料等问题，但经过不断创新与发展，3D打印将成为柔性传感领域极佳的制造手段。