Leak detection in pipe using transient flow and genetic algorithm

An inverse transient method with genetic algorithm (GA) was applied to leak detection in pipeline. Transient flow caused by valve operation was calculated using the characteristics method. The location and discharge of leak were determined so that the difference of the calculated pressure may be minimized from the reference pressure calculated under a given leak condition. Calculations were done for the leak at one and two locations in pipeline. Furthermore, the effect of noise in pressure data was discussed, and the leak locations and leak discharges can be predicted precisely even in the case of noisy data. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju Korea, October 16–19, 2007.     

自适应供水管网泄漏检测定位仪器系统

介绍了一种供水管网泄漏检测及漏点定位的仪器系统检测原理及基本系统构成。系统针对泄漏信号特征因管道材质、内径、管内压力及流量的不同而各异的情况，以及检测现场不可避免的各种突发干扰噪声，采用自适应信号处理技术结合小波分析方法，估计时间延迟检测定位漏点。仪器系统由主机、多个数据采集单元和内装IC电路的加速度传感器组成，基于虚拟仪器技术构建，软硬件结合，实现信号的采集、存储和传输、信号处理及检测信息的显示。     

新型泵类产品密封性测试系统

介绍一种基于ＵＳＯＮ４０００的泵类产品密封性测试系统的组成、工作原理以及气源、夹具和控制台与ＵＳＯＮ４０００主机的接口设计。     

氦检漏技术的在线应用及漏率换算

氦质谱检漏是空调制造业中一项先进的检漏技术,简要介绍该技术的基本原理,检漏装置以及漏率换算方法。     

Design and performance of an advanced metrology building for MIKES

Fundamental metrology is closely linked to the development of science and needs good facilities to achieve low measurement uncertainty in demanding experiments. The laboratories must have good temperature stability, low vibration level, good electromagnetic shielding, clean room air, and humidity control. This paper outlines specification and design principles of a compact laboratory building that brings most of the activities of MIKES under one roof, thus attaining the performance of the most demanding laboratories. The most demanding specifications of temperature and vibration were set for the length and mass laboratories. The tightest room temperature specification was (20 ± 0.05) °C. The vibration level was specified at the tightest level to 1 μm/s at frequencies of 0.1-5 Hz. Electromagnetic shielding was specified at best to 100 dB for plane waves up to 20 GHz. Relative humidity was specified (48 ± 2)% at 20 °C. The specifications were clearly achieved and state of the art metrology laboratories implemented.     

Surface texture metrology for metal additive manufacturing: a review

A comprehensive analysis of literature pertaining to surface texture metrology for metal additive manufacturing has been performed. This review paper structures the results of this analysis into sections that address specific areas of interest: industrial domain; additive manufacturing processes and materials; types of surface investigated; surface measurement technology and surface texture characterisation. Each section reports on how frequently specific techniques, processes or materials have been utilised and discusses how and why they are employed. Based on these results, possible optimisation of methods and reporting is suggested and the areas that may have significant potential for future research are highlighted.     

About the treatment of systematic effects in metrology

A comparison of the text of VIM recent III Edition with that of the GUM and of its contemporary VIM II Edition alights significant differences in the definition of basic measurement terms in the two documents, and with respect to the basic written standards in the field of testing, ISO 5725 and ISO 3534. The paper intends to introduce author’s interpretation of these – and companion – texts, concerning specifically the terminology and the statistical treatment of the influence quantities and of the effects of their variability (in time and standard-to-standard), either related to replicated measurements performed on a single standard (standard ‘reproducibility’) or to the comparisons of different standards, thus involving the concept of ‘accuracy’ and its estimate, and consequently directly relevant to traceability.Another question that arose a few years ago was whether different types of measurand could be the consequence of the different intrinsic nature of different types of standards. It prompted an analysis that resulted in the proposal of considering two distinct ‘classes’ of standards. These classes require different answers to the issue of the treatment of systematic effects. The distinction is relevant, in particular, to the statistical treatment of comparison data, which form the basis of the traceability assessment. The paper is presenting a discussion on the implications of the above distinction, concentrating on cases where systematic effects are dominating the experimental results, a common case in several metrology fields, and on ways to tackle the problem of the correction required by the GUM for standards of class 2 (standards whose values are accurate measures of a common measurand) – a class often not recognised in the general literature.     

A classification of mathematical software for metrology

A classification of mathematical software for metrology is presented. It covers five main disciplines, viz., approximation, optimisation, differential and integral equations, linear algebra, and statistics. For these disciplines working definitions are given, typical objectives provided, software theme areas indicated, and representative applications quoted.     

A CO2 tracer-gas method for local air leakage detection and characterization

A method for local measurement of air leakage rate is presented that can be used to accurately and quickly assess leakage rates across a surface, such as around a valve or hatch in a pressurized gas tank or a window in a building. The method uses a small local enclosure with constant volume placed about a region on the structure under investigation (e.g., a window), which is depressurized and injected with a small concentration of carbon dioxide as a tracer gas. The time variation of the pressure and carbon dioxide concentration inside the enclosure are monitored and used to quantify the leakage flow rate as a function of pressure difference. This method uses a small enclosure with internal mixing so that a quasi-steady-state condition is quickly achieved. Because of the small size of the enclosure, advanced data processing techniques are necessary to reduce uncertainty in determination of the rate of change of the carbon dioxide concentration that arises from sensor variability. Results of a laboratory demonstration of the proposed leakage detection and characterization device are reported for the problem of leakage through a circular hole in a plate with prescribed pressure differences. Experimental results from the laboratory tests are found to be in excellent agreement with results of a numerical simulation of leakage flow through a hole, as well as predictions from a number of empirical equations for this problem found in the literature.     

抗交串自适应噪声对消系统在管道相关检漏技术的应用

管道相关检漏技术通过对泄漏引发的振动信号的处理来完成检漏工作 ,系统原理和结构都非常简单。但在实际应用中 ,它有应用的局限性。在强噪声环境下 ,传感器接收到的包含独立噪声和公共噪声的信号 ,会导致相关曲线中出现虚假的峰值。为提高该类仪器的抗干扰性能 ,本文引入了一种新型的自适应滤波器结构——抗交串自适应噪声对消系统 (CTRANC)。在 Windows95平台上 ,我们编制了一个相关检漏软件 ,其中加入了 CTRANC模块。仿真的结果是令人满意的。     

System for automatic gauge block length measurement optimized for secondary length metrology

This paper presents a contactless system for automatic gauge blocks calibration based on combination of laser interferometry and low-coherence interferometry. In the presented system, the contactless measurement of the absolute gauge block length is done as a single-step operation without any change in optical setup during the measurement. The optical setup is combined with compact gauge block changer with a capacity of 126-ga blocks, which makes the resulting system fully automatic.The paper also presents in detail a set of optimization steps which have been done in order to transform the original experimental setup into the automatic system which meets secondary length metrology requirements. To prove the measurement traceability, we conducted a set of gauge block length measurement comparing data from the optimized system and the established reference systems TESA NPL A.G.I. 300 and TESA–UPC operated in Czech Metrology Institute Laboratory.     

输油管道泄漏监测SCADA系统设计与实现

介绍一套输油管道泄漏检测的SCADA系统设计和实现。采用3点一线式结构，集成了传感器技术、计算机技术、无线通信技术和自动化技术。描述了系统的组成、网络结构及数据采集。采用了瞬态负压波法、流量输差法和压力流量综合法等多种泄漏诊断方法。利用LabView平台开发了系统软件。该系统具有可扩展性。     

大轴径引风机轴承箱漏油治理研究

本文对大直径引风机轴承箱漏油治理提出几点改进措施，供同行参考。     

Creative measurement in view of the scope of metrology

The conception of creative measurements, i.e. measurements when the model of the object is not totally available, is presented. They are compared with routine measurements. The examples of creative measurements of odour and hand are described. The attempted motive of the thesis about metrological sense of modelling and necessity of expansion of the metrology scope is undertaken.     

发动机气门试漏装置的设计

针对柳州五菱汽车有限责任公司柳州机械厂以前用煤油进行发动机气门试漏存在的问题,利用流体力学和密封学的特点研制发动机气门试漏的装置,以提高生产效率和降低成本及改善工作环境等。该装置在柳州五菱汽车有限责任公司柳州机械厂已广泛使用,并取得很大成效。     

基于Lyapunov稳定性理论的气体管道泄漏检测技术研究

管道泄漏检测技术已经在长输气体管道安全运行中起到很重要的作用.本文讨论了基于李雅普诺夫稳定性理论的天然气管道泄漏检测技术,建立了气体管道泄漏动态模型,根据李雅普诺夫意义下对非线性系统的稳定性定义,通过对特征值的分析判断泄漏.实验仿真证明该方法具有一定的可行性.     

Novel application of gas chromatography in measurement of gas flow rate

Real-time volume flow rate of gas component for slowly changing composition mixtures is of chief importance for some special research applications. However, it is always difficult for us to achieve the goal by sophisticated gas flowmeter. In this study, we demonstrate two methods for the problem solution by the flow measurement of acetylene in unsteady gas flow based on online gas chromatography accompanying with a gas mass-flowmeter. For Method 1, high purity methane is applied as an internal standard and the volume flow rate of acetylene is obtained via coherent equations. Method 2 makes fully use of the online gas chromatography automated integration under fixed gas chromatography work conditions. Results have shown that both methods are feasible and effective, and Method 2 is more accurate than Method 1 with relative error less than 0.7%.