This article considers a multiple leaks' localization method in fluid pipelines based on the change in the sound velocity of an ultrasonic signal. First, the sound velocity of an ultrasonic signal is denoised by wavelet packet analysis (WPA). Second, the mathematical relationship between the position of a leak and the change in the sound velocity of an ultrasonic signal at the ends of a pipeline is established based on the motion equation and the continuity equation in the transient flow equation of a pipeline. As a consequence, the localization of the leakage position of the proposed method depends only on the change in the sound velocity of the ultrasonic signal at the ends of the pipeline rather than the time difference in a negative pressure wave arriving at the ends of the pipeline. Finally, the change in the sound velocity of the ultrasonic signal is used and it is proven to be efficient to locate the actual leak number. The simulation results show that the proposed method can locate multiple leak positions in a pipeline.

With the stability, high power generation and low environmental impact of offshore wind resources, offshore wind power is being used as the core power supply to promote the development of global low-carbon economy in the future. Firstly, combined with the characteristics of offshore wind power projects, this paper establishes a reasonable sustainability evaluation system from economy, reliability, environmental protection and safety. Then, in this paper, the mixed-cross weighting based on the coefficient of variation method-order relation method is constructed to determine the weight of project sustainability evaluation indexes. Finally, the function interval and form of the common origin gray clustering evaluation method are modified to determine the sustainability level of the projects. In order to verify the scientificity of the sustainability indexes and the accuracy of the evaluation model, combined with the case background of S offshore wind power project in J Province, the results show that the index that has the greatest impact on the sustainability of offshore wind power is the group participation of projects. At the same time, the improved evaluation method overcomes the problems of the inaccuracy of the rate change of the gray-crossing and membership degree of the common origin gray clustering function and makes the evaluation results more reasonable and authentic. This paper provides a reference for the investment decision of the offshore wind power project to be constructed.