WAPN: a distributed wormhole attack detection approach for wireless sensor networks

As the applications of wireless sensor networks （WSNs） diversify, providing secure communication is emerging as a critical requirement. In this paper, we investigate the detection of wormhole attack, a serious security issue for WSNs. Wormhole attack is difficult to detect and prevent, as it can work without compromising sensor nodes or breaching the encryption key. We present a wormhole attack detection approach based on the probability distribution of the neighboring-node-number, WAPN, which helps the sensor nodes to judge distributively whether a wormhole attack is taking place and whether they are in the influencing area of the attack. WAPN can be easily implemented in resource-constrained WSNs without any additional requirements such as node localization, tight synchronization, or directional antennas. WAPN uses the neighboring-node-number as the judging criterion, since a wormhole usually results in a significant increase of the neighboring-node-number due to the extra attacking link. Firstly, we model the distribution of the neighboring-node-number in the form of a Bernoulli distribution. Then the model is simplified to meet the sensor nodes＇ constraints in computing and memory capacity. Finally, we propose a simple method to obtain the threshold number, which is used to detect the existence of a wormhole, Simulation results show that WAPN is effective under the conditions of different network topologies and wormhole parameters.     

Nonlinear multifunctional sensor signal reconstruction based on least squares support vector machines and total least squares algorithm

Least squares support vector machines （LS-SVMs） are modified support vector machines （SVMs） that involve equality constraints and work with a least squares cost function, which simplifies the optimization procedure. In this paper, a novel training algorithm based on total least squares （TLS） for an LS-SVM is presented and applied to multifunctional sensor signal reconstruction. For three different nonlinearities of a multifunctional sensor model, the reconstruction accuracies of input signals are 0.00136%, 0.03184% and 0.504 80%, respectively. The experimental results demonstrate the higher reliability and accuracy of the proposed method for multifunctional sensor signal reconstruction than the original LS-SVM training algorithm, and verify the feasibility and stability of the proposed method.     

Mechanical analysis and reasonable design for Ti-Al alloy liner wound with carbon fiber resin composite high pressure vessel

To consider the internal pressure loaded by both the cylindrical Ti-Al alloy liner and the carbon fiber resin composite （CFRC） wound layers, two models are built. The first one is a cylinder loaded with the internal pressure in the hoop direction only. In this model, the total hoop direction load is distributed over all layers under the internal pressure. The second one is a cylinder loaded with the internal pressure in the axial direction only. In this model, the total axial load is distributed over all cylinders under the internal pressure. Taking the boundary conditions of the continuous displacement between layers into account, a group of equations are built. From these equations, we get the solutions of stresses in both hoop direction and axial direction loaded by every layer under internal pressures. After the stresses are obtained, a reasonable design can be done. An example is given in the final section of this study.     

一维纳米阵列的制备及其在传感器中的应用

一维纳米阵列结构材料性能独特,在磁性、光学、电化学、催化等领域有很大应用潜力.该文介绍一维纳米阵列主要制备方法,包括模板法、化学气相沉积法、水热法,指出了一维纳米阵列制备技术中存在的不足,对一维纳米阵列在传感器方面的应用进行了概述和展望.     

范德瓦尔斯气体的内压强

1内压强的引入 对于给定的处于平衡态的简单气体系统,如果选择某些独立变量,其他状态参量就可看成是这些独立变量的函数．通过求偏导数得系统参量之间的微分关系,可以把一些不能直接测量的物理量用可以直接测量的物理量来表达．气体系统内部由于分子间存在相互作用力,而致使气压计测出的压强与实际气体内部的压强存在差异,下面我们来讨论它们之间的差异量．     

减压沸腾演示器的制作与使用

在人教版八年级物理上册第四章第三节《汽化与液化》中有一则"不烫手的开水"的阅读材料。文章旨在阐述"水的沸点随压强的减小而降低,随压强的增大而升高"这一物理规律。其中引证了前言中的一个小实验(实验0.1-2)。笔者     

基于传感器的光伏发电监测系统

在线监测技术是保证设备安全可靠运行的关键,尤其是在成本非常高的光伏发电系统中。本文在简单介绍光伏发电系统之后,阐述了如何在光伏发电系统中建立一套监测系统,并着重介绍了在监测系统中起到信号变送作用的几种传感器。     

RFID与无线传感器网络的融合技术研究

探讨了RFID和无线传感器网络走向融合的必然性,在此基础上提出了三种RFID和无线传感器网络相互融合的技术方案,并分析了各种方案的优劣。     

基于MSP430电动车控制系统的设计

该系统基于MSP430F149单片机为电动车的控制核心.整个电动车智能控制系统包括:主控制模块、电机驱动模块、方向控制与速度检测模块,水平检测传感器模块四大部分.其控制过程是通过对各种传感器采集的数据进行处理和判断,实现电动车在跷跷板上不同路段的行驶方向和速度的实时控制以及在相应的位置达到动态平衡,同时用LCD对各指定路段行驶的时间进行实时显示,采用PWM与霍尔传感器实现了对电动车自动往返速度的精密控制.     

小波包分解在迎角传感器信号预处理中的应用

针对基于四象限压力传感器阵列的迎角测量方法中传感器信号受到干扰的问题,讨论了在其预处理中应用小波包变换进行信号分离提取的方法。根据小波包分解理论,对信号进行小波包分解,信号中频率不同的部分落在不同的尺度上,剔除反映干扰的变换尺度,提取出有用信息。结果表明,该方法可很好地提取信号的主要特征信息,也有效地去除了确定性干扰和随机噪声,与传统的信号滤波方法相比较具有明显的优点,同时为后续的信号处理奠定了基础。