第五章 英文文献.docx

第五章 英文文献A new nondestructive technique for measuring pressurein vessels by surface wavesHongjian Zhang a,*, Qing He a, Yong Yan ba National Laboratory of Industrial Control Technology, Institute of Automation Instrumentation, Zhejiang University,Hangzhou 310027, Zhejiang Province, Chinab Department of Electronics, University of Kent, Canterbury, Kent CT2 7NT, UKReceived 22 October 2006; received in revised form 27 May 2007; accepted 29 May 2007AbstractThin-walled pressure vessels are widely used in modern industry. It is important to measure pressure of the vessels. It has been proved that the velocity of ultrasonic propagation in the material could be affected by the stresses applied to it. The pressure measurement should consider the effect of temperature as the velocity of ultrasonic is affected by the temperature and thermo-stress is produced in the vessels wall. Furthermore, the propagation distance of ultrasonic is influenced by thermal deformation due to temperature changes. In consideration of these influencing factors, a modified model of pressure measurement has been developed, and according to this model, a reference method for the temperature compensation is presented. The relationship between the time delay and pressure was established through this method. The correlative time estimation method based on Hilbert–Huang Transform is presented to estimate the time delay. Therefore, a new method for measuring the pressure of thin-walled vessels nondestructively is presented. Two vessels made of differentkinds of materials were used as specimens in our experiments. The results obtain from the tests are used to validate the modified model and demonstrate that the reference method is effective.@2007 Elsevier Ltd. All rights reserved.Keywords: Pressure measurement; Rayleigh waves; Temperature influence; Reference method; Hilbert–Huang Transform .1. IntroductionPressure vessels are widely used in modern industry. In order to ensure that vessels work safely, it is