气压式泄漏检测装置及应用

介绍气压泄漏检测装置及其原理,与水浸没检测方法进行对比,总结其在汽车、摩托车制造业的应用及注意点。     

双谱应用于城市地下燃气管网泄漏检测的研究

城市地下燃气管网由于其压力低,周边环境噪声复杂,决定了其泄漏信号检测的难度。本文从实际出发,提出了一种简单实用的城市地下低压燃气管网泄漏检测系统模型,并根据双谱检测理论,研究了模型中涉及到的泄漏信号、管内流体噪声、城市环境噪声的平稳性、高斯性.采用三种基于双谱的统计量,实现了在0.005～0.01 MPa压力范围内的复杂城市环境噪声中的泄漏检测。在对大量现场实验数据处理的基础上,验证了这种模型及双谱检测法在城市特有的环境噪声中检测泄漏信号的有效性。     

现代管道泄漏检测技术

综述了管道泄漏监测和定位领域中应用的各种现代技术和方法，包括硬件方法和软件方法等，并对这些方法和技术进行了评估。     

钛制压力容器的氦泄漏试验

氦泄漏试验作为一种致密性试验,它的检漏灵敏度远远超过了气密性试验和氨渗漏等试验方法。随着国产化钛制压力容器的不断增多,一些高温高压和密封性要求高的压力容器,制造完成后除了进行常规的致密性试验外,还需要进行氦泄漏试验。钛制压力容器与其它相比,在结构上有较大的区别。选择合理的氦泄漏试验方案,可做到既能检漏又能及时发现漏点,有效地保证钛制容器安全性和可靠性。     

燃气管道泄漏巡检系统研究

燃气管道安全性检测是保障燃气管道安全运营的重要环节.基于超声波检测、嗅觉传感器多源数据融合,以及信号预处理技术,设计并开发了一种适用于城市地下综合管网的燃气管道无损伤、无干扰的巡线检测和泄漏定位系统.该系统具有运行稳定、检测可靠性强和定位精度高的优点,具有较高的应用推广价值.     

泄漏检测中压力传感器的误差补偿

密封性是一项重要的技术指标,在通常采用的气压法泄漏检测中,环境温度会极大影响检测的精度和可靠性。本文对此提出了利用神经网络对压力传感器的误差补偿方法,用Levenberg-marquardt BP(LMBP)算法对网络进行训练,为提高泄漏检测系统的精度和可靠性提供了依据。     

泄漏检测方法及试漏机设计中的几个问题

介绍了当前工业生产过程中以空气为介质进行泄漏检测的基本原理，以及常用的几种泄漏检测方法和选用原则，并对试漏机设计中的一些问题，如密封件的结构设计方法和几种参数的计算方法进行了详细阐述，对从事试漏机设计的技术人员有很好的参考价值。     

汽车离合器管气密性检测设备的设计

设计一种汽车离合器管气密性检测设备。介绍其工作原理与结构、主要技术特点及工作流程,分析影响离合器管气密性检测结果的主要因素。该设备可实现汽车离合器管气密性的负正压、负压、正压3种方式的测试,具有高效率、高精度、半自动化操作等特点,满足离合器管气密性的测试要求。     

基于超声的气体泄漏检测与定位技术在载人航天器中的应用

介绍了基于超声的气体泄漏检测与定位技术的基本原理;介绍了便携式超声检漏、无线超声自动检漏这两类已有设备的组成、工作原理及其在国际空间站、美国航天飞机上的应用情况.以此为参照,初步提出了一种可用于我国未来空间站建设的气体泄漏检测与定位方案.     

Leak detection monitoring system of long distance oil pipeline based on dynamic pressure transmitter

A dynamic pressure transmitter (DPT) is designed in this paper for long distance oil and gas pipeline, of which the design principle and main performance indices are introduced. A novel leak detection monitoring system (LDMS) of long distance oil pipeline based on DPT is designed, and the detection principle and system composition are specified. Dynamic pressure signals along the pipeline can be obtained by the DPT, and then the pipeline leak can be detected by extracting the wavelet packet entropy (WPE) of the signals. The WPE signal feature extraction method for judgment of pipeline leak is explored and developed. In addition, the influence of the wavelet basis and calculating window width on the identification performance of the WPE are further discussed. The application examples show that the DPT has higher detection sensitivity and leak resolution than the traditional pressure transmitter. The system can identify the pipeline leak correctly and reduce false alarm rate effectively. It can also improve detection sensitivity and localization accuracy. The system can correctly detect leaks with a rate of 96.7% and the greatest localization error is 101 m.     

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.     

Biological effects of wear particles generated in total joint replacements: trends and future prospects

Abstract

Joint replacements have considerably improved the quality of life of patients with joints damaged by disease or trauma. However, problems associated with wear particles generated due to the relative motion between the components of the bearing are still present and can lead to the eventual failure of the implant. The biological response to wear debris affects directly the longevity of the prosthesis. The identification of the mechanisms by which cells respond to wear debris and how particles distribute into the human body may provide valuable information for the long term success of artificial joints. During the last few decades, orthopaedic research has been focused on predicting the in vivo performance of joint replacements. However, the exact relationship between material physicochemical properties and inflammatory response has not been fully understood. Laboratory wear simulators provide an accurate prediction of implant wear performance. Though, particles generated from such wear simulators require validation to compare them with particles extracted from peri-implant tissues. This review focuses initially on the current status of total joint replacements (hard on soft and hard on hard bearings) as well as on the tribological behaviour of the potential materials currently under investigation. Then, the correspondence between particles observed in vivo and those generated in vitro to predict the cellular response to wear debris is discussed. Finally, the biological effects of the degradation products generated by wear and corrosion are described.     

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。     

Reconfigurable manufacturing systems: Principles,design, and future trends

Reconfigurable manufacturing systems (RMSs), which possess the advantages of both dedicated serial lines and flexible manufacturing systems, were introduced in the mid-1990s to address the challenges initiated by globalization. The principal goal of an RMS is to enhance the responsiveness of manufacturing systems to unforeseen changes in product demand. RMSs are costeffective because they boost productivity, and increase the lifetime of the manufacturing system. Because of the many streams in which a product may be produced on an RMS, maintaining product precision in an RMS is a challenge. But the experience with RMS in the last 20 years indicates that product quality can be definitely maintained by inserting in-line inspection stations. In this paper, we formulate the design and operational principles for RMSs, and provide a state-of-the-art review of the design and operations methodologies of RMSs according to these principles. Finally, we propose future research directions, and deliberate on how recent intelligent manufacturing technologies may advance the design and operations of RMSs.     

自行小车悬挂输送系统的研究现状与发展趋势

对我国自行小车悬挂输送系统的形成背景、主要功能与特点作了简要介绍,并就自行小车悬挂输送系统的市场需求、发展趋势以及单轨悬挂输送系统和多轨重载悬挂输送系统的应用情况进行了初步分析.     

Overview from oil seeds to industrial products: Present and future oleochemistry

In this paper the available technologies for the preparation of oils, fats and their derivatives using oil seeds as a starting material are discussed. Currently, 15 million tonnes per year of fatty products are used for industrial purposes, and their applications are discussed with particular reference to biodiesel, biolubricants, biosolvents, and printing inks. For each product, the discussion concerns the state of the art as well as the prospects for the future, and existing barriers to development. Also, the problem of glycerol production in terms of both economic significance and new outlets for surplus production is discussed. The paper ends with a brief overview of recent trends in research in the field of chemical and technical utilisation of vegetable oils.     

长输油气管道泄漏监测与准实时检测技术综述

长输油气管道泄漏监测与准实时检测技术一直是各科研院所及石化企业的研究重点。通过分析该技术领域中当前广泛使用或者应用前景广阔的几类方法,总结该技术领域的国内外研究现状和发展趋势,为油气管道泄漏监测技术的进一步发展提供一些建议。     

气体管道泄漏声发射单一非频散模态定位

针对气体管道泄漏声发射信号的多模态、频散特性导致互相关泄漏定位误差大的问题,提出采用单一非频散模态提取的气体管道泄漏声发射定位方法。对检测信号的互谱加窗,并根据模态波数确定窗参数,可获得泄漏声发射信号的单一非频散模态导波的互谱。对单一非频散模态导波的互谱进行傅里叶反变换,得到泄漏声发射中单一非频散模态信号的互相关函数以及时延估计,就可以采用单一非频散模态声速,更准确计算出泄漏位置。对气体管道泄漏进行定位实验,相比用未经分解的泄漏声发射信号进行定位,由于声发射单一非频散模态信号的相关性增强,且选用的声速更准确,定位相对误差平均降低7%以上。这表明,通过提取泄漏信号互谱的单一非频散模态成分进行时延估计,可以提高泄漏检测的有效性和减小定位误差。     

压铸机液压系统泄露原因剖析及解决办法

针对压铸机液压系统泄露的原因进行了剖析,并就解决这一难题进行具体阐述。     

气体管道泄漏模态声发射时频定位方法

针对声发射信号频散特性导致基于时延估计的气体管道泄漏定位误差大的问题,提出一种基于模态声发射时频分析的泄漏定位方法。该方法采用平滑伪Wigner-Ville时频分布对两泄漏信号的互相关函数进行时频分析,利用互相关函数的时频谱可同时提取泄漏信号的时间延迟和与之对应的频率;然后根据泄漏声发射信号的主导模态的频散曲线即可确定该频率对应的声速,利用实时确定的声速和时间延迟并根据两传感器之间的距离即可确定泄漏点的位置。实验结果表明,采用时频分析的气体管道泄漏定位误差与互相关相比减少了6倍。所提出的模态声发射时频定位方法能有效抑制泄漏信号的频散,提高泄漏信号的相关性,从而更适合用于声发射管道泄漏定位。