Applied Ocean Research最新文献

英文中文

Solitary wave-induced 2D seepage effects on sediment incipient motion

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-02-01 DOI: 10.1016/j.apor.2025.104456

Zhaojun Wang , Junning Pan , Biyao zhai , Yue Zhao , Yuerui Jin

Solitary wave theory has been extensively applied to describe wave motions in very shallow water. Previous studies on sand movement induced by solitary waves have typically neglected the effects of seepage flow. This paper examines the effects of two-dimensional (2D) seepage on the Shields number using a semi-analytical model. A modified Shields number, incorporating seepage scaling factors, is derived to assess the influence of seepage forces on sediment incipience. It is found that wave-induced seepage can cause the maximum Shields number to increase by approximately 43.8 %, thereby promoting the incipience of seabed sediment. However, if only the vertical direction is considered, the downward "injection" force would reduce the Shields number. Ignoring the horizontal components of seepage may lead to an underestimation of seepage effects, potentially resulting in an inaccurate evaluation of sediment incipient motion. Parametric studies reveal that, under conditions of greater wave height, water depth, saturation, permeability, and lower Young’ s modulus, the maximum Shields number would noticeably increase due to the combined effects of horizontal and vertical seepage forces. The primary limitation is that the present results apply only to the laminar and partially transitioning regimes; further research is required for strong turbulence (R_e > 5 × 10⁵).

{"title":"Solitary wave-induced 2D seepage effects on sediment incipient motion","authors":"Zhaojun Wang , Junning Pan , Biyao zhai , Yue Zhao , Yuerui Jin","doi":"10.1016/j.apor.2025.104456","DOIUrl":"10.1016/j.apor.2025.104456","url":null,"abstract":"<div><div>Solitary wave theory has been extensively applied to describe wave motions in very shallow water. Previous studies on sand movement induced by solitary waves have typically neglected the effects of seepage flow. This paper examines the effects of two-dimensional (2D) seepage on the Shields number using a semi-analytical model. A modified Shields number, incorporating seepage scaling factors, is derived to assess the influence of seepage forces on sediment incipience. It is found that wave-induced seepage can cause the maximum Shields number to increase by approximately 43.8 %, thereby promoting the incipience of seabed sediment. However, if only the vertical direction is considered, the downward \"injection\" force would reduce the Shields number. Ignoring the horizontal components of seepage may lead to an underestimation of seepage effects, potentially resulting in an inaccurate evaluation of sediment incipient motion. Parametric studies reveal that, under conditions of greater wave height, water depth, saturation, permeability, and lower Young’ s modulus, the maximum Shields number would noticeably increase due to the combined effects of horizontal and vertical seepage forces. The primary limitation is that the present results apply only to the laminar and partially transitioning regimes; further research is required for strong turbulence (<em>R</em><sub>e</sub> > 5 × 10⁵).</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"155 ","pages":"Article 104456"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Simplified FELA-based evaluation of suction caisson bearing capacity in layered sands

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-02-01 DOI: 10.1016/j.apor.2025.104464

Shili Ma , Zhongling Zong , Yifan Ji , Yuwei Wei , Liquan Xie

Evaluating the bearing capacity of a foundation situated on layered soils is crucial for ensuring offshore wind structure stability under varied loading conditions in its service. This study uses finite element limit analysis (FELA) to investigate suction caisson behavior in one- and two-layered cohesionless soils from the Bohai Sea under purely vertical and combined loading. A key innovation is the introduction of a simplified method to analyze ultimate vertical bearing capacity, employing a theoretical retaining wall model that aligns closely with FELA results. The effective interface frictional angle is proposed as a parameter for assessing caisson performance under lateral loads and moments. The research also explores failure modes and combined load yield surfaces, considering soil layer thickness. The research indicates that as the internal friction angle of soils rises, the critical rupture angle for the active sliding body progressively increases, leading to the mobilization of deeper soil layers. The failure mode of suction caissons under lateral loading remains consistent, while moment loading results in deep rotational failure. Additionally, the study confirms the accuracy of existing elliptical equations in describing failure envelopes and introduces new findings on the influence of soil layer thickness on eccentricity parameters and failure envelope characteristics.

{"title":"Simplified FELA-based evaluation of suction caisson bearing capacity in layered sands","authors":"Shili Ma , Zhongling Zong , Yifan Ji , Yuwei Wei , Liquan Xie","doi":"10.1016/j.apor.2025.104464","DOIUrl":"10.1016/j.apor.2025.104464","url":null,"abstract":"<div><div>Evaluating the bearing capacity of a foundation situated on layered soils is crucial for ensuring offshore wind structure stability under varied loading conditions in its service. This study uses finite element limit analysis (FELA) to investigate suction caisson behavior in one- and two-layered cohesionless soils from the Bohai Sea under purely vertical and combined loading. A key innovation is the introduction of a simplified method to analyze ultimate vertical bearing capacity, employing a theoretical retaining wall model that aligns closely with FELA results. The effective interface frictional angle is proposed as a parameter for assessing caisson performance under lateral loads and moments. The research also explores failure modes and combined load yield surfaces, considering soil layer thickness. The research indicates that as the internal friction angle of soils rises, the critical rupture angle for the active sliding body progressively increases, leading to the mobilization of deeper soil layers. The failure mode of suction caissons under lateral loading remains consistent, while moment loading results in deep rotational failure. Additionally, the study confirms the accuracy of existing elliptical equations in describing failure envelopes and introduces new findings on the influence of soil layer thickness on eccentricity parameters and failure envelope characteristics.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"155 ","pages":"Article 104464"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Neural prescribed-time dynamic positioning control of semi-submersible platforms with asymmetric input saturation

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-02-01 DOI: 10.1016/j.apor.2025.104444

Chenfeng Huang, Yongsheng Dou, Zuojing Su, Xianku Zhang

This paper presents an adaptive prescribed-time control scheme to the dynamic positioning (DP) system of semi-submersible platforms (SSPs) in the presence of asymmetric input saturation. To eliminate the adverse effect induced by the input saturation, a saturated compensating auxiliary system is introduced. The system singularity problem is removed by automatically enlarging and recovering the velocity error by implanting a modification saturated signals into the velocity error. The dynamic errors are transformed into a new error variable by using a fixed-time tracking performance function (FTTPF). After that, the fixed-time funnel boundaries (FTFBs) will no longer need to be redesigned according to various initial attitude errors. Meanwhile, the trajectories of the attitude errors are limited to the designed boundaries over a finite time interval. In addition, the new errors in the closed-loop system are guaranteed to be semi-global uniformly ultimately bounded (SGUUB). Finally, two simulations are performed to illustrate the effectiveness and superiority of the proposed scheme.

{"title":"Neural prescribed-time dynamic positioning control of semi-submersible platforms with asymmetric input saturation","authors":"Chenfeng Huang, Yongsheng Dou, Zuojing Su, Xianku Zhang","doi":"10.1016/j.apor.2025.104444","DOIUrl":"10.1016/j.apor.2025.104444","url":null,"abstract":"<div><div>This paper presents an adaptive prescribed-time control scheme to the dynamic positioning (DP) system of semi-submersible platforms (SSPs) in the presence of asymmetric input saturation. To eliminate the adverse effect induced by the input saturation, a saturated compensating auxiliary system is introduced. The system singularity problem is removed by automatically enlarging and recovering the velocity error by implanting a modification saturated signals into the velocity error. The dynamic errors are transformed into a new error variable by using a fixed-time tracking performance function (FTTPF). After that, the fixed-time funnel boundaries (FTFBs) will no longer need to be redesigned according to various initial attitude errors. Meanwhile, the trajectories of the attitude errors are limited to the designed boundaries over a finite time interval. In addition, the new errors in the closed-loop system are guaranteed to be semi-global uniformly ultimately bounded (SGUUB). Finally, two simulations are performed to illustrate the effectiveness and superiority of the proposed scheme.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"155 ","pages":"Article 104444"},"PeriodicalIF":4.3,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143328412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimization and performance analysis of a track tristable nonlinear energy sink subjected to impulsive, harmonic and sea wave excitations

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-01-01 DOI: 10.1016/j.apor.2024.104404

Haobo Li , Hu Ding , Tienchong Chang , Liqun Chen

A traditional track nonlinear energy sink (TNES) is very sensitive to input energy. In order to extend effective energy threshold range of a TNES, a track tristable nonlinear energy sink (TTNES) with rotational inertia is proposed. Firstly, motion equations of a linear structure coupled with a TTNES are derived. The TTNES can translate into the track bistable NES (TBNES) and the track monostable NES (TMNES, traditional TNES) by adjusting track shape parameters. Secondly, equilibrium stability and bifurcation of a TTNES are determined. Then, analytical analysis and vibration reduction performance of a TTNES are conducted under impulsive excitations. In addition, approximate analysis and vibration reduction performance of a TTNES are carried out under harmonic excitations. Finally, a TTNES is applied to vibration mitigation of an offshore platform under sea wave excitations. The results show the TTNES exhibits better vibration reduction performance and higher robustness than traditional TNES when subjected to impulsive and harmonic excitations. In addition, the TTNES can effectively reduce the response of an offshore platform under sea wave excitations. This research provides the necessary theoretical basis for designing and applying the TTNES.

{"title":"Optimization and performance analysis of a track tristable nonlinear energy sink subjected to impulsive, harmonic and sea wave excitations","authors":"Haobo Li , Hu Ding , Tienchong Chang , Liqun Chen","doi":"10.1016/j.apor.2024.104404","DOIUrl":"10.1016/j.apor.2024.104404","url":null,"abstract":"<div><div>A traditional track nonlinear energy sink (TNES) is very sensitive to input energy. In order to extend effective energy threshold range of a TNES, a track tristable nonlinear energy sink (TTNES) with rotational inertia is proposed. Firstly, motion equations of a linear structure coupled with a TTNES are derived. The TTNES can translate into the track bistable NES (TBNES) and the track monostable NES (TMNES, traditional TNES) by adjusting track shape parameters. Secondly, equilibrium stability and bifurcation of a TTNES are determined. Then, analytical analysis and vibration reduction performance of a TTNES are conducted under impulsive excitations. In addition, approximate analysis and vibration reduction performance of a TTNES are carried out under harmonic excitations. Finally, a TTNES is applied to vibration mitigation of an offshore platform under sea wave excitations. The results show the TTNES exhibits better vibration reduction performance and higher robustness than traditional TNES when subjected to impulsive and harmonic excitations. In addition, the TTNES can effectively reduce the response of an offshore platform under sea wave excitations. This research provides the necessary theoretical basis for designing and applying the TTNES.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"154 ","pages":"Article 104404"},"PeriodicalIF":4.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Research on the influence of environmental loads on the rheological properties of laterite nickel ore during liquefaction

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-01-01 DOI: 10.1016/j.apor.2025.104418

Zihao Zhao , Wanqing Wu , Heping Wang , Yu Zhou , Yueyang Sun , Maocheng Huang , Qinggong Zheng

Liquefaction is one of the main causes of catastrophic accidents during sea transport of liquefiable cargo. Complex rheological processes are often required when liquefying liquefiable cargo. In order to study the rheological properties of the liquefaction process, Cyclic Triaxial Test was used to study the liquefaction process of laterite nickel ore under different consolidation pressures and dynamic loads. The rheological properties during the liquefaction process were quantitatively analyzed based on the apparent viscosity η_ap. Subsequently, the liquefaction process was quantitatively described using rheological characteristic parameters and phase transition points (N_s, N_l) were defined to divide different stages. The phase transition mechanism was combined with the shear stress-shear strain rate curve, and the effects of initial effective consolidation pressure σ′₀, axial dynamic load σ_d, and number of cycles N on the rheological characteristics of laterite nickel ore were further analyzed. Finally, an explicit expression of η_ap during liquefaction was obtained by an intelligent algorithm, which could be a data basis for subsequent risk research of liquefiable cargo during sea transport. This study provides a method for quantitative analysis of load and rheological properties of liquefiable cargo.

{"title":"Research on the influence of environmental loads on the rheological properties of laterite nickel ore during liquefaction","authors":"Zihao Zhao , Wanqing Wu , Heping Wang , Yu Zhou , Yueyang Sun , Maocheng Huang , Qinggong Zheng","doi":"10.1016/j.apor.2025.104418","DOIUrl":"10.1016/j.apor.2025.104418","url":null,"abstract":"<div><div>Liquefaction is one of the main causes of catastrophic accidents during sea transport of liquefiable cargo. Complex rheological processes are often required when liquefying liquefiable cargo. In order to study the rheological properties of the liquefaction process, Cyclic Triaxial Test was used to study the liquefaction process of laterite nickel ore under different consolidation pressures and dynamic loads. The rheological properties during the liquefaction process were quantitatively analyzed based on the apparent viscosity <em>η<sub>ap</sub></em>. Subsequently, the liquefaction process was quantitatively described using rheological characteristic parameters and phase transition points (<em>N<sub>s</sub>, N<sub>l</sub></em>) were defined to divide different stages. The phase transition mechanism was combined with the shear stress-shear strain rate curve, and the effects of initial effective consolidation pressure <em>σ′</em><sub>0</sub>, axial dynamic load <em>σ<sub>d,</sub></em> and number of cycles <em>N</em> on the rheological characteristics of laterite nickel ore were further analyzed. Finally, an explicit expression of <em>η<sub>ap</sub></em> during liquefaction was obtained by an intelligent algorithm, which could be a data basis for subsequent risk research of liquefiable cargo during sea transport. This study provides a method for quantitative analysis of load and rheological properties of liquefiable cargo.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"154 ","pages":"Article 104418"},"PeriodicalIF":4.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Real-time synthesis of the dynamic responses of floating bodies to waves for maritime simulators

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-01-01 DOI: 10.1016/j.apor.2024.104393

Luca Donatini , Jeroen Verwilligen , Guillaume Delefortrie , Marc Vantorre , Evert Lataire

A new implementation of the Fourier approach to synthesize spectral waves in real-time was recently published by the authors, based on an efficient GPU implementation and on a very flexible definition of the wave inputs. This paper presents an extension of the method to deal with the time-domain synthesis of frequency-domain responses of floating bodies, which can be calculated offline with a linear seakeeping solver. The frequency-domain responses are mapped from frequency/direction space to wavenumber space in order to match the same wave components used by the synthesis of the ocean surface, and they are transformed into time-domain responses by means of Inverse Discrete Fourier Transforms. Given the large number of elementary wave components required for a realistic visualization of the ocean surface, the synthesis of dynamic responses becomes computationally expensive and was implemented on GPUs relying on parallel reduction algorithms to speed up the summations. The performance of the GPU implementation was investigated, showing how the present method can synthesize multiple dynamic responses in real-time even when dealing with many elementary wave components. The physical accuracy of the technique proposed in the paper was assessed by simulating a virtual wave measurement buoy: the frequency-domain responses of the buoy were calculated with a linear seakeeping solver and then synthesized according to the proposed method. Then, the timeseries of buoy motions were used to reconstruct directional wave spectra, which proved to be in very good agreement with the wave spectra provided as inputs for the simulations.

{"title":"Real-time synthesis of the dynamic responses of floating bodies to waves for maritime simulators","authors":"Luca Donatini , Jeroen Verwilligen , Guillaume Delefortrie , Marc Vantorre , Evert Lataire","doi":"10.1016/j.apor.2024.104393","DOIUrl":"10.1016/j.apor.2024.104393","url":null,"abstract":"<div><div>A new implementation of the Fourier approach to synthesize spectral waves in real-time was recently published by the authors, based on an efficient GPU implementation and on a very flexible definition of the wave inputs. This paper presents an extension of the method to deal with the time-domain synthesis of frequency-domain responses of floating bodies, which can be calculated offline with a linear seakeeping solver. The frequency-domain responses are mapped from frequency/direction space to wavenumber space in order to match the same wave components used by the synthesis of the ocean surface, and they are transformed into time-domain responses by means of Inverse Discrete Fourier Transforms. Given the large number of elementary wave components required for a realistic visualization of the ocean surface, the synthesis of dynamic responses becomes computationally expensive and was implemented on GPUs relying on parallel reduction algorithms to speed up the summations. The performance of the GPU implementation was investigated, showing how the present method can synthesize multiple dynamic responses in real-time even when dealing with many elementary wave components. The physical accuracy of the technique proposed in the paper was assessed by simulating a virtual wave measurement buoy: the frequency-domain responses of the buoy were calculated with a linear seakeeping solver and then synthesized according to the proposed method. Then, the timeseries of buoy motions were used to reconstruct directional wave spectra, which proved to be in very good agreement with the wave spectra provided as inputs for the simulations.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"154 ","pages":"Article 104393"},"PeriodicalIF":4.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of current on the hydroelastic behaviour of floating flexible circular structure

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-01-01 DOI: 10.1016/j.apor.2024.104387

P. Amouzadrad, S.C. Mohapatra, C. Guedes Soares

An analytical model of wave-current interaction with a moored floating circular structure has been developed using Timoshenko-Mindlin beam theory. The analytical solution is derived utilising the matched eigenfunction expansion method, combined with orthogonal relations and Bessel functions. The convergence study of the analytical solution for different current speeds on the deflection amplitude, bending moment, and shear forces is demonstrated. Further, the correctness of the current solution is validated against existing published numerical results and experimental datasets and multiple outcomes of vertical displacement, bending moment, shear force, reflection and transmission coefficients on the current speed, and various design and physical parameters are examined. It has been noted that the current speed influences the structural responses significantly, and the present analysis may help understand the design parameters needed to model a VLFS application for ocean space utilisation.

引用次数: 0

Linear stability and numerical analysis of gas hydrate dissociation in hydrate bearing sediments

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-01-01 DOI: 10.1016/j.apor.2024.104394

Yan Zhang , Jiangong Wei , Xuhui Zhang , Wanlong Ren , Xiaobing Lu , Hongsheng Guo , Tianju Wang

The stability of gas hydrate (GH) dissociation is crucial for understanding and predicting various hazards triggered by GH dissociation, such as landslides and gas blowouts. This study employs linear stability analysis and numerical simulation approaches to investigate the dynamics of GH dissociation under depressurization and heating. An instability criterion is derived, emphasizing conditions where the environmental heat supply exceeds the heat absorption by GH. We analyze the spatial and temporal evolution of key parameters, such as pore pressure, GH volume fraction, temperature, and strength, across different dissociation zones within the sediment. It is observed that pore pressure and temperature increase rapidly over time in unstable conditions, resulting in GH dissociation completing in approximately 10 s and a sharp decrease in the strength of hydrate-bearing sediments (HBS). Our findings offer insights into the behavior of HBS during GH dissociation and elucidate the formation mechanism of potential hazards associated with GH dissociation.

{"title":"Linear stability and numerical analysis of gas hydrate dissociation in hydrate bearing sediments","authors":"Yan Zhang , Jiangong Wei , Xuhui Zhang , Wanlong Ren , Xiaobing Lu , Hongsheng Guo , Tianju Wang","doi":"10.1016/j.apor.2024.104394","DOIUrl":"10.1016/j.apor.2024.104394","url":null,"abstract":"<div><div>The stability of gas hydrate (GH) dissociation is crucial for understanding and predicting various hazards triggered by GH dissociation, such as landslides and gas blowouts. This study employs linear stability analysis and numerical simulation approaches to investigate the dynamics of GH dissociation under depressurization and heating. An instability criterion is derived, emphasizing conditions where the environmental heat supply exceeds the heat absorption by GH. We analyze the spatial and temporal evolution of key parameters, such as pore pressure, GH volume fraction, temperature, and strength, across different dissociation zones within the sediment. It is observed that pore pressure and temperature increase rapidly over time in unstable conditions, resulting in GH dissociation completing in approximately 10 s and a sharp decrease in the strength of hydrate-bearing sediments (HBS). Our findings offer insights into the behavior of HBS during GH dissociation and elucidate the formation mechanism of potential hazards associated with GH dissociation.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"154 ","pages":"Article 104394"},"PeriodicalIF":4.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143166950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Greedy dynamic reward algorithm-based coverage path planning for unmanned sailboats in non-stationary wind environments

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-01-01 DOI: 10.1016/j.apor.2024.104382

Jinkun Shen , Zhongben Zhu , Guiqiang Bai , Zhongchao Deng , Yifan Xue , Xiaojian Cao , Xiaokai Mu , Hongde Qin

Unmanned sailboats, powered by wind, are well-suited for long-term island patrols but face challenges in maneuverability due to wind constraints, limiting route flexibility. This study addresses the issue of coverage path planning by proposing a Greedy Dynamic Reward Algorithm that incorporates wind conditions and sailboat kinematic constraints. A sailboat movement model is developed using a velocity prediction program. With dynamic rewards assigned to map grids based on wind direction, trajectory, and obstacles, the sailboat selects the grid with the highest reward among the available options for its next move. In cases of deadlock, a Breadth-First Search algorithm identifies the nearest uncovered node, and an improved artificial potential field method is employed to navigate to that node. Key strategies, including occupying the relatively most upwind position and disabling movement directions based on the sailed path, effectively minimize overlap and enhance the trackability of the path. Simulation results demonstrate the algorithm's robustness and adaptability in both single-island and archipelago environments, even under changing wind conditions. Furthermore, the study discusses potential directions for algorithm optimization.

{"title":"Greedy dynamic reward algorithm-based coverage path planning for unmanned sailboats in non-stationary wind environments","authors":"Jinkun Shen , Zhongben Zhu , Guiqiang Bai , Zhongchao Deng , Yifan Xue , Xiaojian Cao , Xiaokai Mu , Hongde Qin","doi":"10.1016/j.apor.2024.104382","DOIUrl":"10.1016/j.apor.2024.104382","url":null,"abstract":"<div><div>Unmanned sailboats, powered by wind, are well-suited for long-term island patrols but face challenges in maneuverability due to wind constraints, limiting route flexibility. This study addresses the issue of coverage path planning by proposing a Greedy Dynamic Reward Algorithm that incorporates wind conditions and sailboat kinematic constraints. A sailboat movement model is developed using a velocity prediction program. With dynamic rewards assigned to map grids based on wind direction, trajectory, and obstacles, the sailboat selects the grid with the highest reward among the available options for its next move. In cases of deadlock, a Breadth-First Search algorithm identifies the nearest uncovered node, and an improved artificial potential field method is employed to navigate to that node. Key strategies, including occupying the relatively most upwind position and disabling movement directions based on the sailed path, effectively minimize overlap and enhance the trackability of the path. Simulation results demonstrate the algorithm's robustness and adaptability in both single-island and archipelago environments, even under changing wind conditions. Furthermore, the study discusses potential directions for algorithm optimization.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"154 ","pages":"Article 104382"},"PeriodicalIF":4.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143167006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Beach nourishment with coarse sediments: An in-situ investigation on the issues of abrasion and chipping

IF 4.3 2区工程技术 Q1 ENGINEERING, OCEAN

Applied Ocean Research

Pub Date : 2025-01-01 DOI: 10.1016/j.apor.2024.104409

Chiara Favaretto , Duccio Bertoni , Alessandro Pozzebon , Luca Martinelli , Giovanni Sarti , Piero Ruol

The use of coarse sediments for beach nourishment represents an alternative solution to structural interventions for the protection of coasts that are exposed to energetic waves. Predicting the mass loss of fill material due to abrasion and scouring is crucial for proper nourishment design, as it has implications for the littoral sediment budget and sediment stability under extreme wave conditions. The present study aims at characterising the typical abrasion and chipping of coarse sediments used for beach nourishments, providing insights into their correlation with the wave energy flux incident on the coast. Estimation of weight loss and roundness variability is obtained through RFID (Radio Frequency IDentification) sediment tracking technology, 3D scanning techniques, and Los Angeles tests. The 1 year and 7 months in-situ investigation was carried out at Marina di Pisa (Italy), an artificial beach where the size of supplied pebbles was significantly reduced after few months of typical wave climate, jeopardizing the sediment stability and the lifetime of the nourishment. The methodology could be applied to other beaches and lithologies to establish a database of weight loss useful for coastal managers and engineers.

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