基于多声学传感器融合的管道泄漏检测方法研究

针对单一类型传感器检测管道泄漏的局限性,本文提出了一种基于多声学传感器融合的管道泄漏检测方法.它将振动传感器和声音传感器相结合以获取泄漏点声波信号,通过对这两种声波信号提取某种特征量进行相应的融合计算推断出管道泄漏是否发生.实验结果表明,该种方法能有效地提高管道泄漏检测的准确性.     

Leak detection methods for glass capped and polymer sealed MEMS packaging

This paper presents the limitations of the helium leak test when applied to typical MEMS packages. A novel closed-form expression is presented which allows the determination of the minimum cavity volume package that can be accurately tested using the helium leak test method in conjunction with a standard gross leak test. This expression can be used to find optimum test parameters for packages with cavity volumes greater than 2.6 × 10⁻³ cm³. Hermeticity testing using FTIR and Raman spectroscopy are considered as potential methods to overcome the limitations of the helium leak test method.     

Multi-leak detection and isolation in fluid pipelines

A multi-leak detection system for pipelines is designed and tested. The multi-leak detection problem is solved using only sensors of flow and pressure at the extremes of the duct, and using the analytical redundancy given of these measurements. The leak detection design is based on a distributed pipeline model that is discretized in space and assumes a set of leaks distributed through the duct. Leak location is accomplished by evaluating the residuals of a bank of unknown input observers that are robust against one leak and sensitive to the rest. Simulation and experimental results are reported to demonstrate the effectiveness of the proposed approach when two leaks appear simultaneously.     

Map building method for urban gas pipelines based on landmark detection

This paper presents a map building method for an in-pipe robot to navigate inside urban gas pipelines autonomously, whose configuration is unknown or partially known. In the first, we explain the reason why the navigation in the pipeline is difficult and then, present a method for obtaining a robot’s posture by using a pipeline’s unique geometrical features. The robot can obtain its heading direction by detecting the standardized geometries of pipe elements. Based on the method, we propose a robot controller consisting of discrete and continuous controllers. The discrete controller is activated by pre-defined events and generates appropriate paths for exploration. The continuous controller receives the desired path and physically moves the robot to the desired path. The method is implemented in an in-pipe robot, called MRINSPECT-V and its effectiveness is validated.     

基于分布式光纤传感器的输气管道泄漏检测方法

针对传统方法难以精确诊断输气管道泄漏的难题,提出采用准分布式光纤B ragg光栅(FBG)传感技术实现天然气管道泄漏的在线监测技术。利用一条FBG光缆作为传感器,并行铺设在天然气管道附近,拾取管道由于泄漏、附近机械施工和人为破坏等事件产生的压力和振动信号,通过匹配光栅法和自动识别技术检测管道泄漏并进行定位。实验结果表明:该方法可以实现对天然气管道泄漏进行诊断并定位。     

Leak detection from rural aqueducts using airborne remote sensing techniques

Water companies require quick methods of identifying leakage from rural subterranean aqueducts over large areas. This research assessed the possibility of locating water leaks using airborne remotely sensed data and thus considered if such leaks expressed unique and identifiable features. Analysis of soil moisture and vegetation biomass inferred using Airborne Thematic Mapper imagery enabled two known leaks to be highlighted as distinct from their immediate surroundings on the Vyrnwy Aqueduct, North West England.     

基于负压波法的输油管道泄漏检测定位系统

为实现对石油管道的泄漏进行检测并定位,简要分析了国内外输油管道泄漏检测定位方法及其应用现状,重点研究了负压波泄漏检测与定位算法在实际中的应用.尤其对负压波定位公式中需要的首、末站压力拐点的时间差,即各站压力下降的拐点寻找进行了比较深入的研究与分析.在此基础上设计了一套基于ADAM5510的泄漏检测系统,给出了系统的总体组成结构、各部分功能及软件设计思想.现场试验表明设计的泄漏检测与定位方法具有实用价值.     

An experimental comparison of superpixels detection methods for contour detection

Recently, many superpixels detection methods have been proposed and used in various applications. We are interested in which method is more suitable for the application of contour detection. In this paper, superpixels are evaluated on BSDS500 dataset in two different aspects. On the one hand, contours are directly provided by the boundaries of superpixels and experiments show that better results could be achieved by the superpixels with irregular shapes than those with regular shapes and similar sizes. On the other hand, contours are further detected from those candidate positions which are confirmed by the boundaries of superpixels through the operation of dilation. In this situation, experiments show that competitive results could also be achieved by some superpixels with regular shapes and similar sizes. Besides, we propose a superpixels detection method called watershed-based graph (WG), by which superpixels with irregular shapes could be produced. Firstly, a graph is constructed from an over-segmented map which is achieved through a watershed algorithm. Then, to get the desired superpixels, the graph is segmented by merging neighbor segments in an order of decreasing similarity. Experiments show that higher efficiency could be achieved by WG with a moderate worse contour quality than its original graph-based method.     

Graph regularization methods for Web spam detection

We present an algorithm, witch, that learns to detect spam hosts or pages on the Web. Unlike most other approaches, it simultaneously exploits the structure of the Web graph as well as page contents and features. The method is efficient, scalable, and provides state-of-the-art accuracy on a standard Web spam benchmark.     

Evaluating deadlock detection methods for concurrent software

Static analysis of concurrent programs has been hindered by the well-known state explosion problem. Although many different techniques have been proposed to combat this state explosion, there is little empirical data comparing the performance of the methods. This information is essential for assessing the practical value of a technique and for choosing the best method for a particular problem. In this paper, we carry out an evaluation of three techniques for combating the state explosion problem in deadlock detection: reachability searching with a partial-order state-space reduction, symbolic model checking and inequality-necessary conditions. We justify the method used for the comparison, and carefully analyze several sources of potential bias. The results of our evaluation provide valuable data on the kinds of programs to which each technique might best be applied. Furthermore, we believe that the methodological issues we discuss are of general significance in comparison of analysis techniques     

利用分布式光纤传感技术检测天然气管道泄漏

简述了基于Sagnac光纤干涉仪原理的天然气管道泄漏检测系统理论模型和实验系统,并对系统的性能进行了理论分析和实验研究,实验结果与理论分析相吻合,表明该系统可以实现对天然气管道的泄漏检测及定位。     

液体管道的泄漏仿真

为了找出管道参数的动态变化规律,基于管道的机理模型,通过引入附加边界条件,对泄漏量、泄漏位置和泄漏上升时间对管道内参数的影响进行仿真。结果表明,其他两个因素保持不变的条件下,泄漏量主要影响管道参数的幅值,泄漏上升时间主要影响其波形,泄漏位置会同时影响其幅值和波形,而管道泄漏量和孔的大小及其位置密切相关,而且泄漏管道参数具有和停泵显著不同的特征,可以为运行指导、泄漏检测和人员培训提供必要的辅助手段。     

Leak detection in an experimental heat exchanger process: amultiple model approach

An application of a multiple model nonlinear filtering technique is discussed for the detection of leaks in a heat-exchanger process. The results of simulation study and an experimental study on a laboratory heat-exchanger process are presented. A simple decision logic scheme (threshold crossing) is used to process the outputs of the leak-detection algorithm to indicate the status of the process, i.e. whether or not there is a leak. The results of the study provide preliminary indication of the feasibility of the proposed diagnostic technique to detect small leaks in an experimental heat-exchanger process. The study also indicates that the technique is robust in the midst of significant flow disturbances on the inlet water flow, using only simple models for processing of the outlet temperature data, but is sensitive to the aggregate heat transfer parameter used in the detection algorithm     

Evaluation of methods for ridge and valley detection

Ridges and valleys are useful geometric features for image analysis. Different characterizations have been proposed to formalize the intuitive notion of ridge/valley. In this paper, we review their principal characterizations and propose a new one. Subsequently, we evaluate these characterizations with respect to a list of desirable properties and their purpose in the context of representative image analysis tasks     

Linear and kernel methods for multivariate change detection

The iteratively reweighted multivariate alteration detection (IR-MAD) algorithm may be used both for unsupervised change detection in multi- and hyperspectral remote sensing imagery and for automatic radiometric normalization of multitemporal image sequences. Principal components analysis (PCA), as well as maximum autocorrelation factor (MAF) and minimum noise fraction (MNF) analyses of IR-MAD images, both linear and kernel-based (nonlinear), may further enhance change signals relative to no-change background. IDL (Interactive Data Language) implementations of IR-MAD, automatic radiometric normalization, and kernel PCA/MAF/MNF transformations are presented that function as transparent and fully integrated extensions of the ENVI remote sensing image analysis environment. The train/test approach to kernel PCA is evaluated against a Hebbian learning procedure. Matlab code is also available that allows fast data exploration and experimentation with smaller datasets. New, multiresolution versions of IR-MAD that accelerate convergence and that further reduce no-change background noise are introduced. Computationally expensive matrix diagonalization and kernel image projections are programmed to run on massively parallel CUDA-enabled graphics processors, when available, giving an order of magnitude enhancement in computational speed. The software is available from the authors' Web sites.     

Leak detection and localization in water distribution networks: Review and perspective

In this paper, leak detection and localization in water distribution networks will be reviewed. In particular, the paper presents the evolution of the methods from model-based towards data-based approaches, listing, describing and comparing the main and/or most recent methods of both categories. Besides, the practical applicability in real water utilities of different existing methods is discussed, outlining the advantages and limitations of model-based and data-driven methods for this task. A well-known case study is used to compare some of the more promising methods and illustrate their performances. Perspectives of the future evolution of the current existing methods are also provided.     

两种用于微型生化分析的光探测方法

针对微流控分析芯片样品剂量少与微流体芯片集成等要求,设计了两种易于集成在芯片内的,用分光光度法对混合后液体的吸收光谱进行探测的方法。实验利用460～800nm的可见光光源,采用了直接探测法和消逝波探测法对样品进行探测。通过两种方法的比较证明:直接探测法具有原理简单、消耗样品量少、结构容易实现等优点;消逝波探测法具有需要样品量极少、灵敏度高、易于集成等优点。     

基于动态压力变送器的输油管道泄漏检测与定位系统

设计了一套基于动态压力变送器的输油管道泄漏检测与定位系统,阐述了其系统组成和检测原理.通过动态压力变送器获取管道的动态压力信号,采用基于经验模态分解的方法提取信号的特征向量,再利用支持向量机实现对管道泄漏的识别.最后采用相关时延估计算法获得管道泄漏点的位置.通过现场应用实例表明,动态压力变送器具有更高的检测灵敏度和泄漏分辨力.该系统能够对管道泄漏进行正确识别,可以有效地降低误报警率,并提高了泄漏检测的灵敏度和定位精度.     

内存泄漏检测工具与评估方法

内存泄漏是软件系统中常见的一种错误,会持续消耗内存,致使系统运行效率下降,甚至导致系统崩溃。内存泄漏的检测工具主要可以分为两类:一类是使用基于程序扫描分析技术的静态工具;另一类则是监视实时内存分配状态进行判别的动态工具。如何评估工具检测内存泄漏的能力,相关的标准并不明确。通过对内存泄漏的认识与了解,对相关工具能力进行了调研与分析,提出了一个内存泄漏工具的评估标准。