1 Introduction
The ship pipelines, as the safest and a cost-effective de-vices for liquids transportation [1], are the significant components of the ship, ensuring the stability of the voyage and meeting the normal needs of the crews and passengers[2]. However, pipeline leakage is a threat to ship operation, mem-bers' safety, and marine environment pollution [3]. Typical causes of wear and corrosion in pipelines include the vibration, high temperature in the cabin environment [4] or hu-man sabotage[5]. In recent years, several leakage detection technologies have been developed to locate the position of ship pipeline leakage. Manual inspection is the most com-mon method, which has a high accuracy for the larger leak-age location, but limited by the responsibility and experi-ence of the inspector. Furthermore, the manual inspection has low accuracy for invisible leakage in pipelines, and the inspection is discontinuous, since the large pipelines num-bers and the scattered distribution. Thus, methods based on multi-type sensors are proposed [6], containing the acoustic sensor[7], infrared sensor [8], fiber optic sensors [9], and ultrasonic flow sensor [10]. These sensors detecting and locating pipeline leakage rely on the pressure, temperature, den-sity, flow rate or sonic velocity information. However, their insensitive to low liquid level volumes leads to a detection difficult in minor leakage and limits the further intelligent application [11], [12]. Thus, the design of an effective sensor for detecting invisible and minor leakage in ship pipeline is still a challenge.