基于物联网的燃气管网泄漏检测系统研究

根据城市公共安全管理的需求,设计并实现了一种基于物联网的燃气管网泄漏检测系统。采用高精度压电式动态压力传感器、无线传感器网络和GPS模块实现泄漏瞬变压力波信号的实时同步采集。为保证数据远程传输的实时性和可靠性,采用4G模块MC7710和STM32F405RG微处理器完成了4G网关的设计。远程数据中心采用基于互功率谱相位的广义互相关时延估计方法对现场信号分析和处理,实现了管网中燃气泄漏点的定位。实验结果表明,该系统数据传输稳定可靠,泄漏定位准确度高,能够满足燃气管网泄漏检测的需要。     

压力容器微泄漏点的非接触超声定位检测研究

文中研究了压力容器微小泄漏点的定位检测问题。基于FUS-40CR型超声传感器,研制了一套高灵敏度非接触超声测漏定位系统。该系统利用4个传感器实现了时差法的测漏定位,并利用Lab Windows/CVI软件编译了泄漏定位程序。利用该系统对设计的一个能够改变漏孔孔径和压力的小型压力罐进行了微小泄漏点的非接触定位检测实验。实验结果表明:在罐内气压为0.6 MPa、漏孔直径不小于0.2 mm的情况下,可以得到满意的定位测试结果。     

在线极性相关器的研究

本文介绍了一种新型的微机化软硬结合的在线极性相关器,采用分级扫描,成功地解决了相关测量中实时相关分析的统计测量精度与响应速度的矛盾。该相关器已用于液固两相(纸浆)流量计中,获得了满意的结果。采用相关测量技术,是解决许多难测流体流速、流量测量的有效途径之一,在线相关器是相关测量的关键组成部分。我们研制的微机化软硬结合的在线极性相关器,成功地解决了在线极性相关分析统计测量精度与响应速度的矛盾,在液固两相(纸浆)流量计中得到了实际应用。为开拓相关分析的在线应用奠定了良好的基础。     

桥壳中段同轴度测量装置的结构设计

为提高铸造桥壳中段测量精度和测量效率,文中提出采用专用测量设备实现在线测量,动态控制产品重要特性指标通过对产品结构和测量要求的深入分析,找出了测量装置设计中多点测头、测头防护、多品种快速切换装置等技术难点的解决方案,实现了铸造桥壳中段基于该装置实时在线测量,为桥壳中段的动态质量控制做出了创造性的探索     

基于GSM/GPRS的供水管网泄漏监测与定位系统

介绍了一种基于GSM/GPRS网络的供水管网泄漏监测与定位系统,由管网监测终端实时采集管网流量、流速、流向和压力,通过GSM/GPRS网络实现远程数据传输,利用基于GIS的Web技术实施城域化、网络化、信息化的管网状态监管.针对供水管网突发性的爆管和地下泄漏特点,综合运用了负压波和流量检测法进行泄漏模式识别与漏点定位,能够及时、准确的发现和定位泄漏点,并在实际使用中取得良好的效果.     

夹钳式超声相关流量计及其在液／固两相流测量中的应用

本文叙述了一种可应用于液/固两相流的夹钳式脉冲超声相关流量计。检测随机流动噪声用的两对超声波传感器,是用卡钳装置牢固地夹紧在被测管道的外壁面上,不和被测流体直接接触,不会对流体产生任何阻碍作用。在线实时相关器的设计,采用了极性相关和峰值溢出检测原理。为兼顾仪表的流速测量范围和测量精度的要求,采用了可自寻最佳采样频率的闭环反馈式方案。     

高精度非接触式激光测径仪设计与研究

针对电线、光纤等线缆在线快速实时检测精度不高的问题,设计实现了高精度非接触式激光测径仪。该测径仪采用"标准棒法"光学测量系统,以FPGA+ARM为控制器,采用呈90°夹角的激光器和CCD接收器方式以及分组处理数据的方法,来实现在线快速实时监测。测试结果表明,测径仪测量范围为0.1～15mm,示值误差不大于±3um,并且具有通过RS485通信接口在PC机上实现实时显示测量数据的功能。     

供水管网泄漏定位研究与检测系统开发

在分析泄漏声波在管线中传播特性的基础上,根据自适应滤波时延估计与泄漏定位的原理,设计与实现了管网泄漏定位系统中的传感器及信号调理电路、数据采集与通信电路、数字滤波以及泄漏定位软件等,并进行了系统集成.在实现的系统中,传感器采集到的泄漏声信号被转换成12位数字量,通过通信端口读入计算机.为了得到准确的定位结果,对采集到的数据采用了选频段滤波、分时段时延估计、根据信号幅值的相对强弱进行抑制突发强干扰.现场试验与运行结果表明:系统硬件和软件流程运行正确,达到了设计的需求;泄漏定位结果误差小于0.5 m,能够满足实际测量的要求.     

基于Φ-OTDR技术的城市地下供水管网主干线泄漏检测与定位

为解决城市地下供水管网水泄漏无法检测及定位的问题,提出基于相位敏感的光时域反射仪Φ-OTDR技术的水声泄漏检测技术。该技术作为一种分布式光纤振动传感器,具有多点探测、灵敏度高、结构简单、低成本等先天优势,应用于城市地下供水管道的实时监测,具有很好的发展前景。本文搭建供水管道水泄漏的模拟实验平台,通过分析泄漏信号的特征频谱分量,排除现场实验环境中其他干扰因素的影响,实现对水泄漏信号的识别,分离与定位,并得到了较高的信噪比。理论分析和现场模拟实验表明,Φ-OTDR技术可以应用于城市地下供水管网漏水事件的监测与定位。     

远程抄表漏水点定位及故障诊断模型的研究

研究了管道泄漏负压波信号的产生机理、信号传播规律,在对比分析了流量检测法、压力梯度法、负压波检测法的基础上,最终确定以负压波检测法及定位公式结合能量统计算法,实现漏水点定位。解决的主要问题包括漏水点定位计算、远程通信传输协议设定和远程抄表故障诊断模型。研究的基本内容包括水管网节点布置、安置压力传感器、信号放大,远程通信协议的设计,实时检测信号出现异常时提示,并且能计算出漏水点的位置。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...