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Indexed by:期刊论文

Date of Publication:2008-12-01

Journal:CHINA OCEAN ENGINEERING

Included Journals:SCIE、EI、ISTIC、CSCD、Scopus

Volume:22

Issue:4

Page Number:561-574

ISSN No.:0890-5487

Key Words:submasine pipelines; condition identification; free span; kernel discriminant analysis (KDA); frequency structure

Abstract:Free spanning pipelines arc suspended between two points on an uneven seafloor. The variations of structural conditions, such as the changes in soil property, flow velocity, axial force and span length etc., directly affect working performance of the whole submarine pipeline system. But until now few researches have focused on condition identification for free span (CIFS). A method to identify the operational conditions of free spanning submarine pipelines based on vibration measurements is proposed in this paper. Firstly, the in-posedness, of CIFS is analyzed in detail. Secondly, the framework for CIFS based on the nonlinear kernel discriminant analysis (KDA) is established. Thirdly, the internal structural characteristics of natural frequencies, normalized frequencies and frequency change ratios are studied. And then the condition feature vector for CIFS is extracted by use of the vibration measurements. Finally, the validity of the proposed approach is evaluated by a case study. The results demonstrate that the proposed approach can effectively identify each condition of free span when condition variation occurs even if under measurement noise. It is concluded that the proposed method is a promising tool for CIFS in real applications.