基于全向型S_0模态磁致伸缩传感器的无参考缺陷成像方法研究

Lamb波具有传播距离远、衰减小等优点,能在板结构中实现大范围、高效率的损伤检测和监测,在无损检测和结构健康监测领域具有极大的应用潜力。针对板结构大范围健康监测问题,为了能周向一致地激励出模态单一Lamb波S0模态,提高缺陷成像能力,基于磁致伸缩效应,设计并制作一种全向型S0模态磁致伸缩传感器,由印刷电路板线圈,圆柱磁铁,圆形镍片组成。试验验证研制的传感器能够在铝板中有效激励出单一的S0模态,并测试其频率响应特性以及全向性,结果表明设计传感器中心频率为365 k Hz,并具有较好的全向性。进一步利用研制的全向型S0模态磁致伸缩型传感器组成稀疏传感器阵列。采用自激自收的方式对铝板结构中缺陷进行检测。利用离散圆弧成像与数据融合算法相结合的方法对多组数据进行处理,消除常规的稀疏传感器阵列成像时对结构健康状况下的信号依赖,无需健康状况下的信号作为参考,实现了在板结构中缺陷的定位和成像。

水库涵管检测用十字结构全向型管道机器人研究（英文）

该管道机器人是为了提高地方水利员人工检测水库(山塘)涵管隐患的工作效率而设计的,做到机器换人,大幅度提高野外检测效率。水库涵管检测用十字结构全向型管道机器人的结构是由一个十字结构作为机器人的基本框架,在十字的各个驱动腿顶端安装驱动轮,可以根据管壁具体地形自适应变化。该机器人的通行平面是管道中心水平面,可以最大限度地避开山塘涵管淤泥问题,且能大幅度提高管道错位越障能力。

全向型天线在北斗遥测终端上的应用研究

北斗遥测终端是目前航标管理中监控航标状态的重要手段,但在日常管理中发现有些北斗遥测终端不能按时上传数据,造成了一定程度的数据丢包。为了改善数据丢包现象,我们研究分析了产生问题的原因,提出了改善终端天线的设想,试制了新终端样品并完成了测试。本文简要介绍了全向型天线的工作原理和在北斗遥测终端上实际的应用情况,通过测试与实际使用总结了新型天线的优势与存在的问题,并且提出相关建议以及对未来的展望。

全向感知型传感器覆盖率优化研究

为了降低全向感知型应变传感器网络的节点布置数量以及提高传感网络的测量精度,研究全向感知型传感器覆盖率优化问题。分析了全向感知传感器数学模型,对覆盖率优化问题进行数学化描述,建立优化函数,确定优化目标。使用全局人工鱼群算法对所建立的传感器覆盖率优化函数进行求解,得出最优传感器节点布置方案。研究结果表明:在传感器节点数量较少时,使用优化方法得到的覆盖率提升较为明显;随着节点数量的增多,使用优化方法得到的覆盖率曲线逐渐平缓。使用所研究的优化方法后,测量的应变相比人工随机布置传感器测量值更接近真实值,具有较高的测量精度。

基于超声水平剪切波的加筋板结构损伤识别

采用一种新型的厚度剪切式(d15)全向型水平剪切波(SH波)压电换能器,结合离散椭圆算法,对加筋铝板结构焊接处的损伤进行超声无损检测,并对单损伤、多损伤以及损伤程度等问题进行了分析,验证了基于超声SH波的无损检测技术识别加筋板焊接结构处损伤的有效性,为SH波在实际工程中的应用提供了技术支撑。

登高望远——WiFi高增益天线选购指南

随着电脑配件价格的逐步走低，更多的家庭用户拥有了多台电脑，与此同时，无线联网以其便利和整洁性成为不少家庭联网的考虑方案，无线网络产品的选购也渐渐成为热门话题。我们知道无线网络在距离过远或有障碍物的情况下会有较大的信号衰减，这将影响无线网络连接的质量，而本文正是从原理到选购，让你明明白白地用最低廉的价格解决这个普遍的问题。

Simulation Analysis of Macroeconomic Policy Orientations' Effects on the Industrial Economy——Based on Dynamic CGE Model

There are three different orientations of the macroeconomic policies,namely,factor-expansion,prudent-continuation and structural-adjustment.The paper uses the dynamic CGE model to simulate the effects of the three different orientations on the economy,and arrives at the following conclusions:while the factor-expansion policies can lead to growth of economic output,they also result in the further imbalance in the industrial structure and the "crowding-out effect" on the private investment.In addition,such growth is unsustainable in the long run;the growth of the industrial economy will decline rapidly to a lower level after reaching a certain high level.The prudent-continuation policies refer to the continuation of the current policies that sustain the current trends of the industrial economy,and such policies reduce the growth of the industrial economy to a lower level in the long run.The structural-adjustment policies reduce the economic output at the current stage;however,it can bring a gradual improvement of industrial structure and a balance of the supply and demand.In the long run,the optimized structure will improve the total factor productivity(TFP) and the production-possibility frontier,and thereby realize a longterm steady and rapid growth of the industrial economy.Four policy recommendations are proposed based on the simulation of the models,including taking the structural adjustment as the fundamental orientation of macroeconomic policies,lowering the "floor level" of economic growth with macro regulation,giving play to the fundamental role of market mechanism in structural adjustment and increasing the role of TFP in the growth of the industrial economy.

GA-SVC model and application of comprehensive evaluation of coal mine essential safety management

In order to evaluate the level of the coal mine essential safety management, the comprehensive index system was designed base on the connotation principle of the mine essential safety management. Due to the disadvantage of index weight setting by subjective idea in the former method, support vector classification algorithm was used to assess the level of coal mine essential safety management. According to the advantages of the global search capability of the genetic algorithm, support vector classification parameters optimization method was proposed based on genetic algorithm, and genetic algorithm-support vector classification model of coal mine essential safety management assessment was established. Learning samples were constructed on the basis of former data of mine essential safety management evaluation. The test results show that the genetic algorithm-support vector classification model has higher evaluation accuracy and good generalization ability, and the advantage of no need for artificial setting of index weight and absence of the subjective factors influence to evaluation results.

Safety evaluation of Dagangshan arch dam resisting strong earthquakes with a rate-dependency anisotropic damage model

This paper presents a model to simulate the safe behavior of Dagangshan arch dam with a rate-dependency anisotropic damage model. This model considers the damage of asymmetry and anisotropy under cyclic loading of tension and compression, and it is used in the compiled finite element code. The material parameters used in the model can be identified from uniaxial static and dynamic experiments. Thereafter, it is used for analyzing damage and failure patterns of the dam subjected to water pressure and strong earthquakes. The numerical results show that it is necessary to consider both asymmetry between tension and compression and anisotropy of damage. Severe damage regions of the dam reveal brittle and risky positions clearly. Meanwhile damage patterns show the failure trend and safety behaviors of the dam. These results match well with that of the experiments carried out in DUT. The proposed model may be used to predict the damage patterns and potential failure modes of concrete structures like the dam. And the aseismic performance of the dam can be figured out.