Condition Identification Based on Vibration Measurements for Free Spanning Submarine Pipelines

• 出 处: 中国海洋工程（英文版）
• 发表日期: 2004年期
• 关键词: submasine pipelines condition identification free span kernel discriminant analy
• 基金项目: This project was financially supported by the Key Program of National Natural Science Foundation of China;and the Main Program of the Ministry of Education of China

Free spanning pipelines are 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 ill-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.