基于AOA和TDOA的无线传感器网络三维联合定位算法

结合二维空间中基于波的干涉的角度测量算法和基于到达时间差的定位算法,提出一种适用于三维空间的无线传感器网络定位算法。算法先测量信标节点和待测节点间的角度和距离,然后精确计算出待测节点坐标。该算法复杂度较低,最少只需三个信标节点,采用分布式计算,定位精度高。仿真表明,算法能够较精确地计算三维空间中传感器节点的位置。     

应用于土壤温度测量的无线传感器节点设计

针对传统土壤温度测量方法的缺陷，设计了一种由MCU、传感器、无线收发模块组成的传感器节点。测量时将整个传感器节点埋入土层长期监测土壤温度，通过无线方式进行传输数据，解决了传统测量方法中劳动强度和测量准确性不能兼顾的矛盾。实验证明，通过对节点的电磁兼容和低功耗设计，使节点的通信距离和电池使用寿命均达到了理想的效果。     

基于改进粒子群优化的无线传感器网络定位算法

无线电干涉定位系统获取的干涉距离是4个传感器节点间距离的线性组合值.针对以两个节点间距离作为输入的传统定位算法无法直接利用上述干涉距离进行定位的问题,提出一种基于改进粒子群优化的定位方法.利用干涉距离的实验数据,分析比较了遗传算法和改进粒子群优化在无线传感器网络节点定位问题中的性能.结果表明,基于改进粒子群优化的定位方法的平均耗费时间远远小于基于遗传算法的定位方法,具有更高的优化效率.     

光纤应变传感器的研究

本文采用在一段单模光纤两端镀膜的方法构成光纤法布里－珀罗干涉腔,导出干涉腔反射光的数学模型,给出干涉腔与其它器件连接构成的干涉式光纤应变传感器的一般理论和测量方法。     

最小跳数路由无线传感器网络中的节点距离测量

无线传感器网络中的间接距离测量是一种性价比极高的距离测量方法,但目前测量精度还有待进一步提高。根据最小跳数路由无线传感器网络的行为特征,提出了一种基于最小跳数路由及其路由重复数的节点距离测量算法,与DV-hop算法相比,借助路由重复数较大地提高了距离测量精度。理论分析及仿真结果表明,该算法在节点密集分布的无线传感器网络中具有很好的效果。     

无线传感器网络RCF-MAC协议研究

射频充电（ RFC）技术是一种通过基站发射射频电波为传感器节点补充电量的新兴技术。但在RFC无线传感器网络中,多基站同时发射能量时产生的能量干涉衰减现象会明显降低充电效率,此外,能量传输与数据通信共享信道会降低整个网络的吞吐量。针对上述问题,提出了RFC—MAC协议,为提高充电效率,将请求充电传感器节点周围的基站按距离分为两组,两组基站分时能量传输,以避免能量干涉衰减现象;传感器网络中设双信道,分别用于能量传输与数据通信,以提高网络的吞吐量。仿真结果表明：RFC—MAC协议显著提高了传感器节点的充电效率和平均网络吞吐量。     

一种移动无线视频传感器节点的覆盖算法

在现有的无线传感器网络覆盖算法的研究中,缺乏对移动节点路径规划的研究,而针对具有视频传感器节点的网络仍使用普通传感器圆形覆盖区域的测量方法来计算覆盖面积,并不完全符合实际情况.基于这两方面的原因,本文提出了一种适用于无线视频传感器节点的最大覆盖算法,并提出一种对于视频传感器节点覆盖面积的计量方法.该算法能够使节点在保证网络连通性的前提下,达到最大的有效监测范围.此外,本文建立了相应的仿真实验模型,对该算法的有效性和覆盖面积进行了实验与分析.结果表明,本算法的节点监测面积大约为使用随机运动算法的节点监测面积的1.5倍左右,并可以保证网络的连通性.     

基于精细化梯度的传感器网络节点距离测量

定位在无线传感器网络中具有极其重要的作用,而距离测量往往是定位的前提、寻求低成本、低开销、高精度的分布式传感器网络节点距离测量算法是本文的主要目的.根据无线传感器网络最小跳数梯度场中节点精细化梯度值的分布特征,提出了一种基于精细化梯度的传感器网络节点距离测量方法DV-FGI.与DV-hop算法相比,DV-FGI保留了DV-hop算法低成本、低开销的优点,具有更高的测量精度,并将节点距离测量分辨率从节点有效通信半径提高至网络节点间距.理论分析及仿真结果表明,该算法在节点密集分布的无线传感器网络中具有很好的效果.     

月球环境下无线传感器网络节点的设计

讨论了月球环境对无线传感器节点的影响;调查与分析了现有的无线传感器节点,对其中的几种著名节点作了简要介绍,并分析了它们对月球环境的适应性;介绍了月球环境下的一种无线传感器网络(WSNs)节点的结构,并从节点的角度讨论了将WSNs用于月球表面要解决的主要问题和关键技术。     

一种基于不同光谱透射比的光纤温度传感器

介绍一种基于多层介质膜干涉滤光片的不同光谱透射比随温度变化的光纤温度传感器 ,采用两个不同波长的透射光功率的比值作为传感器的输出 ,以消除光源功率波动对测量结果的影响。实验结果表明 ,该测量方法是完全可行的。     

支持测试节点按需调整的分布式测试调度模型

针对分布式测试系统动态调整测试节点能力差、测试总体效率低的问题,提出一种实用的支持测试节点按需调整的分布式测试调度模型。该模型利用M/M/N排队理论描述分布式测试任务到达和处理的概率分布,提出待处理强度指标来动态调配测试节点,基于此建立任务调度数学模型,并利用0-1线性整数规划法求解,实现了分布式测试执行时间最短的目的。仿真实验结果证明,该模型可以根据测试需求的变化动态调整测试节点数量,利用简单实用的调度方法,有效地降低测试节点负载,提高了测试效率。     

一种无线传感器网络节点定位算法的改进

利用无线信号强度实现了煤矿安全监测无线传感器网络（WSNs）节点问的自定位,提出了一种新的节点定位算法,介绍了算法的基本原理和实现方法。该算法不需要任何额外的硬件支持,节点间通信开销少。仿真结果表明：所提出的算法可以有效地提高WSNs节点的定位精度。     

New acoustic positioning system for an underwater robot using multiple frequencies

Nowadays, robots are used for many types of underwater work, and knowing their position accurately is very important. Conventional positioning systems are based on the time difference or phase lag of sound waves. However, such systems are complex and expensive, and real-time positioning is difficult and not very accurate. We propose a new system using the loss of sound propagation and a sensor network. In a previous study, we separated directly arrived waves from received waves and measured their amplitude or power. Using this data, we calculated the distance. However, the signal included many types of reflected wave, and we were not able to obtain a correct value over long distances where the direct waves cannot be separated from the influence of the reflected waves. In this study, we propose a new method based on sounds at multiple frequencies. This method uses sounds of several different frequencies, and sends them sequentially at constant intervals. The distance can be calculated by taking the average power of the signals received. The advantage of this method is that it is not necessary to use any separating process, and longer distances can be measured.     

Statistical characteristics of anomalously large surface waves based on computational experiments

The computational experiments on modeling surface waves, which are used for studying the statistics of the occurrence of extremely large surface waves depending on the parameters of the initial waves, are considered. The sudden occurrence of abnormally large waves in the ocean is a big hazard for marine vessels and structures. In recent years, incontrovertible evidence of this phenomenon, such as instrumentation records and photographs, has been presented. The main method of studying the phenomenon of rogue waves in this work is computational experiments based on the complete nonlinear hydrodynamic equations of an ideal liquid with a free surface. The method of conformal variables that is used for the original system of equations enables one to make effective and accurate calculations by computers and computing complexes. According to the experimental results, the statistics of the occurrence of anomalously large surface waves is studied. The use of dissipation and pumping in these computational experiments has made it possible to perform continuous calculations that are not stopped if a rogue wave occurs. The intensity of the occurrence of rogue waves depending on the values of the squares of the mean steepness and wave dispersion is estimated. It is shown that doubling the computational region almost doubles the intensity. The proposed procedure of the computational experiments allows estimating the average waiting time of a rogue wave in the assigned region.     

Parallelization schemes for 2-D hydrodynamics codes using the independent time step method

In order to realize the full potential of parallel processing, investigation into new types of physics codes has begun. Two guiding physical principles behind the new approaches are the avoidance of any non-essential synchronization and the use of local information whenever possible. Consideration of these principles has given rise to a new method for the time advance of computation, called the Independent Time Step Method (ITSM).

The basic approach of ITSM is to advance local spatial regions using locally determined time steps. Regions which share no information may be advanced simultaneously. This relaxation of time coordinate constraints finds a natural counterpart in the Free Lagrange approach to the spatial coordinates for a hydrodynamics code. In the Free Lagrange approach, information is evaluated at spatial points (nodes) which move in concert with the fluid motion. Accordingly, this hydrodynamics code is characterized by nodes which change relationships in the course of the computation. The Voronoi construction technique is used to determined a triangularization for the nodes.

This paper describes parallelization strategies for ITSM on a 2-D hydrodynamics code. Pertinent issues are both the scheduling of nodes to processes and the lower-level synchronization mechanisms. Fairness and efficiency are discussed, and results of experiments run on a 16-processor Sequent Balance 21000 are presented.     

传感器在管道超声导波检测中的应用

管道超声导波检测技术是一种新兴的无损检测方法。利用该技术可以在一点对管道进行快速而全面的检测,节省检测时间,减少劳动强度。而由于导波的频散、多模态特性和管道工作条件、结构尺寸的不同,使得在超声导波检测中对导波的激励方式和传感器的使用要求也不尽相同。传感器的选择对管道超声导波检测的实现十分重要。简要回顾了五种不同类型传感器在管道导波检测中的工作机理、特性及其应用。     

基于GSO算法的最小连通支配集问题求解

经典的最小连通支配集(MCDS)计算是NP难问题。为此,提出一种利用萤火虫优化算法求解该难题的新方法。把网络中的每个节点当作一个萤火虫个体,以节点度为基础构成荧光素,通过概率选择和荧光素调节机制,使个体被吸引向邻接的高亮度个体,从而由所选出的个体组成网络的支配集。经连接和修剪处理后,得到MCDS的近似解。在无线传感器网络模型的单位圆盘图上进行模拟实验,结果表明,该算法得到的连通支配集规模较小,更接近集中式算法的结果。     

节点分类及失效对网络能控性的影响

复杂系统间的相互作用能够用复杂网络描述.复杂网络中某些节点遭受攻击或破坏会造成网络故障,导致整个网络能控性变化.不同节点失效会对网络能控性有不同的影响.本文提出一种网络节点的分类方式,将网络中的节点根据边的方向和匹配关系分成九种类型,并给出了辨识节点类型的算法.另外,本文给出了基于此分类方式下复杂网络中某类节点失效时,...     

最优二叉树的逆推调位启发式算法设计

针对构造有个带权叶子结点的最优二叉树提出一种新颖的启发式算法,该算法根据递推算法的逆推原理,利用结点位置的调动产生的权的变化值来决定节点在最优二叉树中的位置。该算法在使二叉树达到最优的运算过程中,完全区别于以往的哈夫曼算法。逆推调位算法步骤简明,速度迅捷,最后以举例的方式说明该算法的实效性。     

Bounding and shaping the demand of generalized mixed-criticality sporadic task systems

We generalize the commonly used mixed-criticality sporadic task model to let all task parameters (execution-time, deadline and period) change between criticality modes. In addition, new tasks may be added in higher criticality modes and the modes may be arranged using any directed acyclic graph, where the nodes represent the different criticality modes and the edges the possible mode switches. We formulate demand bound functions for mixed-criticality sporadic tasks and use these to determine EDF-schedulability. Tasks have different demand bound functions for each criticality mode. We show how to shift execution demand between different criticality modes by tuning the relative deadlines. This allows us to shape the demand characteristics of each task. We propose efficient algorithms for tuning all relative deadlines of a task set in order to shape the total demand to the available supply of the computing platform. Experiments indicate that this approach is successful in practice. This new approach has the added benefit of supporting hierarchical scheduling frameworks.