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Analysis of vibration signal responses on pre induced tunnel defects in friction stir welding using wavelet transform and empirical mode decomposition

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Defence Technology（防务技术） 2019年第6期15卷 885-896页

作者： J.rabi T.Balusamy r.raj jawahar Vinayaka Mission’s Kirupananda Variyar Engineering College SalemIndia Department of Mechanical Engineering Government College of EngineeringSalemIndia Department of Mechanical Engineering Dynamech Design SolutionsChennaiIndia

Among many condition-monitoring systems in welding operation,Defect identification is an important method to ensure the precision in finishing *** stir welding is a solid state welding process used to join two metals without the use of electrode at lower *** aim of this present work is to identify and localize the tunnel defect in aluminum alloy and measure the distance of the defect zone in the time domain of the vibration signal during Friction stir *** vibration signals are captured from the experiments and the burst in the vibration signal is focused in the analysis.A signal-processing scheme is proposed to filter the noise and to measure the dimensional parameters of the defect *** proposed technique consists of discrete wavelet transform(DWT),which is used to decompose the *** enveloping technique is applied on the decomposed zero padded *** continuous wavelet transform(CWT) has been implemented on detailed signal followed by a time marginal integration(TMI) of the CWT *** mode decomposition(EMD) is used to replace the detailing coefficients from DWT with Intrinsic Mode Function(IMF).Statistical parameters such as mean,kurtosis,S.D and crest factor have been extracted from the final filtered signal for validating the defect welds from the control defect free *** produced were found to be that kurtosis is 7.4402 for tunnel defect induced weld and 3.3862 for defect free *** the increase in kurtosis value predicts the defect zone impact in the *** measurement of the defect zone of the cut 1(voids) and cut 2(tunnel grooves) in correlation with the processed signal is found to produce a much redundant results with an error rate of 0.02.

关键词： welding friction alloy

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Assessment of groundwater quality in the flood plains of upper Palar river, India

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Chinese Journal Of Geochemistry 2012年第1期31卷 15-23页

作者： rutharvel Murthy Kuppuraj Dhanakumar Selvaraj Solaraj Govindaraj Mohanraj rangaswamy jawahar raj Narayanasamy Kumaraswamy Kuppanagounder Department of Geography School of GeosciencesBharathidasan UniversityTiruchirappalli 620024India Department of Environmental Management Bharathidasan UniversityTiruchirappalli 620024India Department of Geology National CollegeTiruchirappalli 620001India

Groundwater is generally presumed to be good for human consumption and is used as a main source of drinking water. Although there are numerous reasons for groundwater pollution, anthropogenic sources are consid-ered as the prime ones. In this study, twenty-two groundwater samples were collected from the flood plains of upper Palar river during the pre- and post-monsoon seasons to assess the extent of pollution and effects on human health. Physico-chemical characteristics of groundwater were analyzed and compared with those of drinking water standards recommended by the World Health Organization (WHO) and the Bureau of Indian Standards (BIS). The Piper's tri-linear diagram shows the nature of alkali earth with the high contents of alkalies and prevailing sulphate in the pre-sent samples. The univariate statistics and correlation analysis were performed to find out the relationships between the variables. The tannery effluents, solid wastes and sewage were suspected to be the predominant sources of pollu-tion in the area.

关键词：地下水污染冲积平原水质评价印度饮用水标准上游物理化学特性世界卫生组织

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