Research

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13 pages, 4092 KiB

Open AccessArticle

Numerical Investigation of the Influence of a Splitter Plate on Mixing Transfer in the Ducts of a Rotary Energy Recovery Device

by Kai Liu, Xuyu Liu, Lijuan Wu, Xingkai Zhang, Baocheng Shi and Lixing Zheng

J. Mar. Sci. Eng. 2023, 11(9), 1804; https://doi.org/10.3390/jmse11091804 - 16 Sep 2023

Viewed by 659

Abstract

The rotary energy recovery device (RERD) is integral in reducing energy consumption in desalination processes. The absence of a physical piston in RERD ducts allows salinity transfer from the brine to the seawater stream, which reduces RERD efficiency. To address this challenge, this [...] Read more.

The rotary energy recovery device (RERD) is integral in reducing energy consumption in desalination processes. The absence of a physical piston in RERD ducts allows salinity transfer from the brine to the seawater stream, which reduces RERD efficiency. To address this challenge, this study investigates the potential of utilizing splitter plates as a flow control technique to decrease the mixing degree within RERDs. Numerical simulations were performed to examine five different splitter plate configurations in RERD ducts in order to identify optimal designs for reducing the mixing degree. The analysis of internal streamlines and vortex distributions revealed that horizontal splitter plates positioned at the duct inlet effectively suppressed swirling flows, while splitter plates positioned at the center of the duct suppressed the formation of flow-induced vortices. This resulted in a more uniform salinity distribution and a reduction in the mass transfer rate between brine and seawater streams. The most significant reduction in the volumetric mixing rate was observed when employing cross-spread splitter plates positioned at the center of the duct. This paper presents an innovative method to reduce the mixing degree in the RERD. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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13 pages, 4924 KiB

Open AccessArticle

An Underwater Triboelectric Biomechanical Energy Harvester to Power the Electronic Tag of Marine Life

by Bo Liu, Taili Du, Xiaoyan Xu, Jianhua Liu, Peng Zhu, Linan Guo, Yuanzheng Li, Tianrun Wang, Yongjiu Zou, Hao Wang, Peng Xu, Peiting Sun and Minyi Xu

J. Mar. Sci. Eng. 2023, 11(9), 1766; https://doi.org/10.3390/jmse11091766 - 09 Sep 2023

Viewed by 1148

Abstract

Implantable electronic tags are crucial for the conservation of marine biodiversity. However, the power supply associated with these tags remains a significant challenge. In this study, an underwater flexible triboelectric nanogenerator (UF-TENG) was proposed to harvest the biomechanical energy from the movements of [...] Read more.

Implantable electronic tags are crucial for the conservation of marine biodiversity. However, the power supply associated with these tags remains a significant challenge. In this study, an underwater flexible triboelectric nanogenerator (UF-TENG) was proposed to harvest the biomechanical energy from the movements of marine life, ensuring a consistent power source for the implantable devices. The UF-TENG, which is watertight by the protection of a hydrophobic poly(tetrafluoroethylene) film, consists of high stretchable carbon black-silicone as electrode and silicone as a dielectric material. This innovative design enhances the UF-TENG’s adaptability and biocompatibility with marine organisms. The UF-TENG’s performance was rigorously assessed under various conditions. Experimental data highlight a peak output of 14 V, 0.43 μA and 38 nC, with a peak power of 2.9 μW from only one unit. Notably, its performance exhibited minimal degradation even after three weeks, showing its excellent robustness. Furthermore, the UF-TENG is promising in the self-powered sensing of the environmental parameter and the marine life movement. Finally, a continuous power supply of an underwater temperature is achieved by paralleling UF-TENGs. These findings indicate the broad potential of UF-TENG technology in powering implantable electronic tags. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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13 pages, 9598 KiB

Open AccessArticle

Experimental Validation of a Fast-Tracking FOCV-MPPT Circuit for a Wave Energy Converter Embedded into an Oceanic Drifter

by Matias Carandell, Daniel Mihai Toma, Andrew S. Holmes, Joaquín del Río and Manel Gasulla

J. Mar. Sci. Eng. 2023, 11(4), 816; https://doi.org/10.3390/jmse11040816 - 11 Apr 2023

Cited by 1 | Viewed by 1243

Abstract

Wave Energy Converters (WECs) are an ideal solution for expanding the autonomy of surface sensor platforms such as oceanic drifters. To extract the maximum amount of energy from these fast-varying sources, a fast maximum power point tracking (MPPT) technique is required. Previous studies [...] Read more.

Wave Energy Converters (WECs) are an ideal solution for expanding the autonomy of surface sensor platforms such as oceanic drifters. To extract the maximum amount of energy from these fast-varying sources, a fast maximum power point tracking (MPPT) technique is required. Previous studies have examined power management units (PMU) with fast MPPT circuits, but none of them have demonstrated their feasibility in a real-world scenario. In this study, the performance of a fast-tracking fractional open circuit voltage (FOCV)-MPPT circuit (sampling period T_MPPT of 48 ms) is compared with a commercial slow-tracking PMU (T_MPPT of 16 s) in a monitored sea area while using a small-scale, pendulum-type WEC. A specific low-power relaxation oscillator circuit is designed to control the fast MPPT circuit. The results demonstrate that by speeding up the sampling frequency of the MPPT circuit, the harvested energy can be increased by a factor of three. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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20 pages, 7310 KiB

Open AccessArticle

Flow-Induced Motion and Energy Conversion of the Cir-T-Att Oscillator in a Flow Field with a High Reynolds Number

by Danjie Ran, Jijian Lian, Xiang Yan, Fang Liu, Nan Shao, Xu Yang and Lingfan Li

J. Mar. Sci. Eng. 2023, 11(4), 795; https://doi.org/10.3390/jmse11040795 - 07 Apr 2023

Viewed by 851

Abstract

The present study aims to systematically investigate the effects of a high Reynolds number on the flow-induced motion and energy conversion of the Cir-T-Att oscillator. Experiments are conducted in six Reynolds number ranges (2.89 × 10⁴~6.51 × 10⁴ < Re [...] Read more.

The present study aims to systematically investigate the effects of a high Reynolds number on the flow-induced motion and energy conversion of the Cir-T-Att oscillator. Experiments are conducted in six Reynolds number ranges (2.89 × 10⁴~6.51 × 10⁴ < Re < 7.71 × 10⁴~15.21 × 10⁴) in regimes of TrSL2, TrSL3 and TrBL0. The system total damping ratio (ζ_total) is adjusted by varying excitation voltages (V_B) with a controllable magnetic damping system. The V_B is varied from 0 V to 165 V, corresponding to 0.082 ≤ ζ_total ≤ 1.153. The amplitude, frequency, fluid force, spectral content, active power, and upper limit of power output are analyzed. The results show that the Reynolds number affects both amplitude and global response characteristics. The active power increases with an increasing Reynolds number within the upper branch. The maximum power output of the Cir-T-Att oscillator reaches 10.43 W, appearing at Re = 14.67 × 10⁴ (D = 0.16 m, ζ_total = 0.468, U_r = 6.34), while the maximum upper limit of power output is 17.80 W at Re = 15.21 × 10⁴ (D = 0.16 m, ζ_total = 0.678, U_r = 6.57). Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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15 pages, 1647 KiB

Open AccessArticle

Optimization Study of Marine Energy Harvesting from Vortex-Induced Vibration Using a Response-Surface Method

by Peng Xu, Shanshan Jia, Dongao Li, Ould el Moctar and Changqing Jiang

J. Mar. Sci. Eng. 2023, 11(3), 668; https://doi.org/10.3390/jmse11030668 - 22 Mar 2023

Cited by 2 | Viewed by 1449

Abstract

Vortex-induced vibration (VIV) of bluff bodies is one type of flow-induced vibration phenomenon, and the possibility of using it to harvest hydrokinetic energy from marine currents has recently been revealed. To develop an optimal harvester, various parameters such as mass ratio, structural stiffness, [...] Read more.

Vortex-induced vibration (VIV) of bluff bodies is one type of flow-induced vibration phenomenon, and the possibility of using it to harvest hydrokinetic energy from marine currents has recently been revealed. To develop an optimal harvester, various parameters such as mass ratio, structural stiffness, and inflow velocity need to be explored, resulting in a large number of test cases. This study primarily aims to examine the validity of a parameter optimization approach to maximize the energy capture efficiency using VIV. The Box–Behnken design response-surface method (RSM-BBD) applied in the present study, for an optimization purpose, allows for us to efficiently explore these parameters, consequently reducing the number of experiments. The proper combinations of these operating variables were then identified in this regard. Within this algorithm, the spring stiffness, the reduced velocity, and the vibrator diameter are set as level factors. Correspondingly, the energy conversion efficiency was taken as the observed value of the target. The predicted results were validated by comparing the optimized parameters to values collected from the literature, as well as to our simulations using a computational-fluid dynamics (CFD) model. Generally, the optimal operating conditions predicted using the response-surface method agreed well with those simulated using our CFD model. The number of experiments was successfully reduced somewhat, and the operating conditions that lead to the highest efficiency of energy harvesting using VIV were determined. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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20 pages, 4046 KiB

Open AccessArticle

Research on a Novel Combined Cooling and Power Scheme for LNG-Powered Ship

by Xiu Xiao, Xiaoqing Xu, Zhe Wang, Chenxi Liu and Ying He

J. Mar. Sci. Eng. 2023, 11(3), 592; https://doi.org/10.3390/jmse11030592 - 10 Mar 2023

Cited by 2 | Viewed by 1296

Abstract

Cold energy recovery in LNG-powered vessels can not only improve the utilization efficiency of energy, but also benefit environmental protection. This paper put forward a new cascade scheme for utilizing flue gas waste heat and LNG cold energy comprehensively. The scheme was integrated [...] Read more.

Cold energy recovery in LNG-powered vessels can not only improve the utilization efficiency of energy, but also benefit environmental protection. This paper put forward a new cascade scheme for utilizing flue gas waste heat and LNG cold energy comprehensively. The scheme was integrated by a dual organic Rankine circulation system (ORC), a high- and low-temperature cold storage system (TCS), an air conditioning system (ACS) and a seawater desalination system (SDS). The working medium of the dual ORC system was firstly determined by considering exergy efficiency and economic index simultaneously. On this basis, the adaptive weighted particle swarm optimization algorithm was employed to enhance thermodynamic performance of the scheme with the net output power as the optimization objective. The maximum net power and annual net interest rate can reach 725.78 kW and $115,300, respectively. Furthermore, the economic benefit of the scheme was analyzed by referring to the running track and the operation condition of the target ship. The results showed that the proposed scheme is a potential large-scale cryogenic technology and can bring considerable economic benefits to ship navigation. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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34 pages, 8835 KiB

Open AccessArticle

Coupled Translational–Rotational Stability Analysis of a Submersible Ocean Current Converter Platform Mooring System under Typhoon Wave

by Shueei-Muh Lin, Didi Widya Utama and Chihng-Tsung Liauh

J. Mar. Sci. Eng. 2023, 11(3), 518; https://doi.org/10.3390/jmse11030518 - 27 Feb 2023

Cited by 1 | Viewed by 848

Abstract

This study proposes a mathematical model for the coupled translational–rotational motions of a mooring system for an ocean energy converter working under a typhoon wave impact. The ocean energy convertor comprises two turbine generators and an integration structure. The configuration of the turbine [...] Read more.

This study proposes a mathematical model for the coupled translational–rotational motions of a mooring system for an ocean energy converter working under a typhoon wave impact. The ocean energy convertor comprises two turbine generators and an integration structure. The configuration of the turbine blade and the floating platform is designed. The two turbine blades rotate reversely at the same rotating speed for rotational balance. If the current velocity is 1.6 m/s and the tip speed ratio is 3.5, the power generation is approximately 400 kW. In the translational and rotational motions of elements under ocean velocity, the hydrodynamic parameters in the fluid–structure interaction are studied. Initially, the hydrodynamic forces and moments on the converter and the platform are calculated and further utilized in obtaining the hydrodynamic damping and stiffness parameters. The 18 degrees of freedom governing equations of the mooring system are derived. The solution method of the governing equations is utilized to determine the component’s motion and the ropes’ dynamic tensions. In the mooring system, the converter is mounted under a water surface at some safe depth so that it can remain undamaged and stably generate electricity under typhoon wave impact and water pressure. It is theoretically verified that the translational and angular displacements of the converter can be kept small under the large wave impact. In other words, the water pressure on the converter cannot exceed the predicted value. The relative flow velocity of the convertor to the current is kept fixed such that the power efficiency of convertor can be maintained as high. In addition, the dynamic tension of the rope is far less than its breaking strength. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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19 pages, 15619 KiB

Open AccessArticle

Offshore Measurements and Numerical Validation of the Mooring Forces on a 1:5 Scale Buoy

by Jens Engström, Zahra Shahroozi, Eirini Katsidoniotaki, Charitini Stavropoulou, Pär Johannesson and Malin Göteman

J. Mar. Sci. Eng. 2023, 11(1), 231; https://doi.org/10.3390/jmse11010231 - 16 Jan 2023

Viewed by 1773

Abstract

Wave energy conversion is a renewable energy technology with a promising potential. Although it has been developed for more than 200 years, the technology is still far from mature. The survivability in extreme weather conditions is a key parameter halting its development. We [...] Read more.

Wave energy conversion is a renewable energy technology with a promising potential. Although it has been developed for more than 200 years, the technology is still far from mature. The survivability in extreme weather conditions is a key parameter halting its development. We present here results from two weeks of measurement with a force measurement buoy deployed at Uppsala University’s test site for wave energy research at the west coast of Sweden. The collected data have been used to investigate the reliability for two typical numerical wave energy converter models: one low fidelity model based on linear wave theory and one high fidelity Reynolds-Averaged Navier–Stokes model. The line force data is also analysed by extreme value theory using the peak-over-threshold method to study the statistical distribution of extreme forces and to predict the return period. The high fidelity model shows rather good agreement for the smaller waves, but overestimates the forces for larger waves, which can be attributed to uncertainties related to field measurements and numerical modelling uncertainties. The peak-over-threshold method gives a rather satisfying result for this data set. A significant deviation is observed in the measured force for sea states with the same significant wave height. This indicates that it will be difficult to calculate the force based on the significant wave height only, which points out the importance of more offshore experiments. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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18 pages, 3689 KiB

Open AccessArticle

Swarm Game and Task Allocation for Autonomous Underwater Robots

by Minglei Xiong and Guangming Xie

J. Mar. Sci. Eng. 2023, 11(1), 148; https://doi.org/10.3390/jmse11010148 - 08 Jan 2023

Cited by 1 | Viewed by 1789

Abstract

Although underwater robot swarms have demonstrated increasing application prospects, organizing and optimizing the swarm’s scheduling for uncertain tasks are challenging. Thus, we designed robot games and task allocation experiments, where the robots have different cooperative attributes, as some are more selfish and others [...] Read more.

Although underwater robot swarms have demonstrated increasing application prospects, organizing and optimizing the swarm’s scheduling for uncertain tasks are challenging. Thus, we designed robot games and task allocation experiments, where the robots have different cooperative attributes, as some are more selfish and others more altruistic. Specifically, we designed two experiments: target search and target moving, aiming to reveal the relationship between individual cooperation and group task achievement in a robot swarm as a collaborative strategy. The task information is shared among the robots, because performing the tasks consumes a certain amount of energy, reducing the robot’s running speed. Our experiments prove that the robot swarms can evolve and enhance their strategies during the game, and will guide guiding future works in designing more efficient robot swarms. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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25 pages, 12147 KiB

Open AccessArticle

Leakage Fault Diagnosis of Lifting and Lowering Hydraulic System of Wing-Assisted Ships Based on WPT-SVM

by Ranqi Ma, Haoyang Zhao, Kai Wang, Rui Zhang, Yu Hua, Baoshen Jiang, Feng Tian, Zhang Ruan, Hao Wang and Lianzhong Huang

J. Mar. Sci. Eng. 2023, 11(1), 27; https://doi.org/10.3390/jmse11010027 - 26 Dec 2022

Cited by 4 | Viewed by 1999

Abstract

Wing-assisted technology is an effective way to reduce emissions and promote the decarbonization of the shipping industry. The lifting and lowering of wing-sail is usually driven by hydraulic system. Leakage, as an important failure form, directly affects the safety as well as the [...] Read more.

Wing-assisted technology is an effective way to reduce emissions and promote the decarbonization of the shipping industry. The lifting and lowering of wing-sail is usually driven by hydraulic system. Leakage, as an important failure form, directly affects the safety as well as the functioning of hydraulic system. To increase the system reliability and improve the wing-assisted effect, it is essential to conduct leakage fault diagnosis of lifting and lowering hydraulic system. In this paper, an AMESim simulation model of lifting and lowering hydraulic system of a Very Large Crude Carrier (VLCC) is established to analyze the operation characteristics of the hydraulic system. The effectiveness of the model is verified by the operation data of the actual hydraulic system. On this basis, a wavelet packet transform (WPT)-based sensitive feature extracting method of leakage fault for the hydraulic system is proposed. Subsequently, a support vector machine (SVM)-based multi-classification model and diagnosis method of leakage fault are proposed. The study results show that the proposed method has an accuracy of as high as 97.5% for six leakage fault modes. It is of great significance for ensuring the reliability of the wing-sail operation and improving the utilization rate of the offshore wind resources. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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13 pages, 2668 KiB

Open AccessArticle

Self-Powered and Robust Marine Exhaust Gas Flow Sensor Based on Bearing Type Triboelectric Nanogenerator

by Taili Du, Fangyang Dong, Meixian Zhu, Ziyue Xi, Fangming Li, Yongjiu Zou, Peiting Sun and Minyi Xu

J. Mar. Sci. Eng. 2022, 10(10), 1416; https://doi.org/10.3390/jmse10101416 - 03 Oct 2022

Cited by 8 | Viewed by 1725

Abstract

Exhaust gas flow takes a vital position in the assessment of ship exhaust emissions, and it is essential to develop a self-powered and robust exhaust gas flow sensor in such a harsh working environment. In this work, a bearing type triboelectric nanogenerator (B-TENG) [...] Read more.

Exhaust gas flow takes a vital position in the assessment of ship exhaust emissions, and it is essential to develop a self-powered and robust exhaust gas flow sensor in such a harsh working environment. In this work, a bearing type triboelectric nanogenerator (B-TENG) for exhaust gas flow sensing is proposed. The rolling of the steel balls on PTFE film leads to an alternative current generated, which realizes self-powered gas flow sensing. The influence of ball materials and numbers is systematically studied, and the B-TENG with six steel balls is confirmed according to the test result. After design optimization, it is successfully applied to monitor the gas flow with the linear correlation coefficient higher than 0.998 and high output voltage from 25 to 106 V within the gas flow of 2.5–14 m/s. Further, the output voltage keeps stable at 70 V under particulate matter concentration of 50–120 mg/m³. And the output performance of the B-TENG after heating at 180 °C for 10 min is also surveyed. Moreover, the mean error of the gas flow velocity by the B-TENG and a commercial gas flow sensor is about 0.73%. The test result shows its robustness and promising perspective in exhaust gas flow sensing. Therefore, the present B-TENG has a great potential to apply for self-powered and robust exhaust gas flow monitoring towards Green Ship. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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20 pages, 5816 KiB

Open AccessArticle

Prediction of Wave Energy Flux in the Bohai Sea through Automated Machine Learning

by Hengyi Yang, Hao Wang, Yong Ma and Minyi Xu

J. Mar. Sci. Eng. 2022, 10(8), 1025; https://doi.org/10.3390/jmse10081025 - 26 Jul 2022

Cited by 5 | Viewed by 2259

Abstract

The rational assessment of regional energy distribution provides a scientific basis for the selection and siting of power generation units. This study, which focused on the Bohai Sea, set 31 research coordinate points in the Bohai sea for assessing the potential/trends of wave [...] Read more.

The rational assessment of regional energy distribution provides a scientific basis for the selection and siting of power generation units. This study, which focused on the Bohai Sea, set 31 research coordinate points in the Bohai sea for assessing the potential/trends of wave energy flux (WEF). We applied a point-to-point time series prediction method which modelled the different geographical coordinate points separately. Subsequently, we evaluated the performance of three traditional machine learning methods and three automated machine learning methods. To estimate WEF, the best model was applied to each research coordinate points, respectively. Then, the WEF was calculated and predicted based on the data of MWP, SWH, and water depth. The results indicate that, for all coordinates in the Bohai Sea, the H2O-AutoML algorithm is superior to the other five algorithms. Gradient boosting machine (GBM), extreme gradient boosting (XGBoost), and stacked ensemble models yielded the best performance out of the H2O algorithms. The significant wave height (SWH), the mean wave period (MWP), and the WEF in the Bohai Sea tended to be concentrated in the center of the sea and dispersed in the nearshore areas. In the year 2000, 2010, 2020, and 2030, the maximum annual average WEF at each research coordinate in the Bohai Sea is around 1.5 kW/m, with a higher flux in autumn and winter. In summary, the results provide ocean parameter characterization for the design and deployment of wave energy harvesting devices. Moreover, the automated machine learning introduced herein has potential for use in more applications in ocean engineering. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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Review

Jump to: Research

26 pages, 7931 KiB

Open AccessReview

Advances in Marine Self-Powered Vibration Sensor Based on Triboelectric Nanogenerator

by Yongjiu Zou, Minzheng Sun, Weipeng Xu, Xin Zhao, Taili Du, Peiting Sun and Minyi Xu

J. Mar. Sci. Eng. 2022, 10(10), 1348; https://doi.org/10.3390/jmse10101348 - 22 Sep 2022

Cited by 5 | Viewed by 3031

Abstract

With the rapid development of advanced electronics/materials and manufacturing, marine vibration sensors have made great progress in the field of ship and ocean engineering, which could cater to the development trend of marine Internet of Things (IoT) and smart shipping. However, the use [...] Read more.

With the rapid development of advanced electronics/materials and manufacturing, marine vibration sensors have made great progress in the field of ship and ocean engineering, which could cater to the development trend of marine Internet of Things (IoT) and smart shipping. However, the use of conventional power supply models requires periodic recharging or replacement of batteries due to limited battery life, which greatly causes too much inconvenience and maintenance consumption, and may also pose a potential risk to the marine environment. By using the coupling effect of contact electrification and electrostatic induction, triboelectric nanogenerators (TENGs) were demonstrated to efficiently convert mechanical vibration movements into electrical signals for sensing the vibration amplitude, direction, frequency, velocity, and acceleration. In this article, according to the two working modes of harmonic vibration and non-harmonic vibration, the latest representative achievements of TENG-based vibration sensors for sensing mechanical vibration signals are comprehensively reviewed. This review not only covers the fundamental working mechanism, rational structural design, and analysis of practical application scenarios, but also investigates the characteristics of harmonic vibration and non-harmonic vibration. Finally, perspectives and challenges regarding TENG-based marine self-powered vibration sensors at present are discussed. Full article

(This article belongs to the Special Issue Advanced Marine Energy Harvesting Technologies)

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