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An Efficient Optimization Design Framework for Low-Resistance Shape of Bionic Amphibious Robot

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China ocean Engineering 2024年第1期38卷 117-128页

作者： ZHANG Dai-yu ZHANG Man-yu WANG Zhi-dong ZHENG Wen-sheng LING Hong-jie HU Jun-ming school of Naval Architecture and ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

To realize the low-resistance shape optimization design of amphibious robots,an efficient optimization design framework is proposed to improve the geometric deformation flexibility and optimization *** the proposed framework,the free-form deformation parametric model of the flat slender body is established and an analytical calculation method for the height constraints is *** method is introduced to carry out the high-precision resistance calculation and a constrained Kriging-based optimization method is built to improve the optimization efficiency by circularly infilling the new sample points which satisfying the ***,the shape of an amphibious robot example is optimized to get the low-resistance shape and the results demonstrate that the presented optimization design framework has the advantages of simplicity,flexibility and high efficiency.

关键词： amphibious robot optimization method free-form deformation CFD-based hydrodynamic calculation

A Time-Domain Numerical Simulation for Free Motion Responses of Two Ships Advancing in Head Waves

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China ocean Engineering 2024年第3期38卷 519-530页

作者： PAN Su-yong CHENG Yong school of Naval Architecture and ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

The constant panel method within the framework of potential flow theory in the time domain is developed for solving the hydrodynamic interactions between two parallel ships with forward *** solving problems within a time domain framework,the free water surface needs to simultaneously satisfy both the kinematic and dynamic boundary conditions of the free water *** provides conditions for adding artificial damping *** the Runge−Kutta method to solve equations related to *** upwind differential scheme is used in the present method to deal with the convection terms on the free surface to prevent waves *** the comparison with the available experimental data and other numerical methods,the present method is proved to have good mesh convergence,and satisfactory results can be *** constant panel method is applied to calculate the hydrodynamic interaction responses of two parallel ships advancing in head *** simulations are conducted on the effects of forward speed,different longitudinal and lateral distances on the motion response of two modified Wigley ships in head *** further investigations are conducted on the effects of different ship types on the motion response.

关键词： ship motions time domain simulation forward speed different distances wave loads

Quantitative Analysis of Frosting Characteristics on the Drip Tray of A Cryogenic Valve for LNG Ships

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China ocean Engineering 2024年第4期38卷 572-585页

作者： BAI Xu CHEN Guan-yu DU Yue XU Cao CHEN Jia-jing school of Naval Architecture&ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

Cryogenic valves play a crucial role in the production and transportation of liquefied natural gas(LNG),and are primarily responsible for efficiently controlling the inflow and outflow of LNG and regulating ***,due to their operation in low-temperature and high-humidity environments,crucial components such as drip trays are susceptible to frosting,which may lead to LNG leakage,thereby causing severe safety *** this study,the user-defined function(UDF)is employed to redevelop Fluent,which integrates the frost growth model with the Eulerian multiphase flow model,to conduct a quantitative analysis of frosting on drip trays of cryogenic *** effects of environmental parameters,such as wind speed,ambient temperature,air humidity,and cold surface temperature on the growth of the frost layer were *** study reveals a limiting wind speed between 1 m/s and 2 m/*** reaching this limit speed,the growth of the frost layer reaches its maximum,and further increases in the wind speed have no significant effect on the growth of the frost ***,the influence of the change in the flow field on droplet impingement and freezing during the growth of the frost layer is considered through the coupling method of the kinematic characteristics of water droplets and the collection coefficient of water *** study identifies the influence of different parameters on the droplet impact efficiency,leading to the modification of the frost layer on the drip tray.

关键词： LNG carrier drip tray frost effective impact coefficient

Study on Effectiveness of Solitary-Wave-Like Form Based on Overtopping Data from Irregular Wave Tests

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China ocean Engineering 2024年第4期38卷 701-710页

作者： LI Xiao-liang Huang Gui-biao school of Naval Architecture&ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China

The previous study conducted by Li(2022)demonstrates that the Goda graph can be adequately represented by a solitary-wave-like form across the entire range of relative water depth,with the exception of the extremely shallow ***,it remains uncertain whether this form is equally effective when applied to test data generated by irregular waves,as the Goda graph was initially developed based on overtopping data from regular wave ***,it is unclear whether this form is suitable for formulating overtopping discharge at composite vertical *** order to address these questions,a 2D overtopping experiment was conducted,incorporating both simple and composite types of vertical walls,with various relative water depths across the entire range,excluding the extremely shallow zone.A novel analysis procedure was developed,which proved to be highly productive and can be considered a general method for data ***,the study yielded two conclusions:(1)the solitary-wave-like form is remarkably effective in formulating overtopping test data generated by irregular waves,regardless of whether the vertical wall is simple or composite,and(2)the resulting formulas exhibit definitely better performance compared with existing formulas.

关键词： solitary-wave-like form overtopping discharge overtopping formula vertical wall

Adversarial attacks against dynamic graph neural networks via node injection

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High-Confidence Computing 2024年第1期4卷 43-51页

作者： Yanan Jiang Hui Xia school of Computer science and technology Ocean University of ChinaQingdao 266100China

Dynamic graph neural networks(DGNNs)have demonstrated their extraordinary value in many practical ***,the vulnerability of DNNs is a serious hidden danger as a small disturbance added to the model can markedly reduce its *** the same time,current adversarial attack schemes are implemented on static graphs,and the variability of attack models prevents these schemes from transferring to dynamic *** this paper,we use the diffused attack of node injection to attack the DGNNs,and first propose the node injection attack based on structural fragility against DGNNs,named Structural Fragility-based Dynamic Graph Node Injection Attack(SFIA).SFIA firstly determines the target time based on the period ***,it introduces a structural fragile edge selection strategy to establish the target nodes set and link them with the malicious node using serial ***,an optimization function is designed to generate adversarial features for malicious *** on datasets from four different fields show that SFIA is significantly superior to many comparative *** the graph is injected with 1%of the original total number of nodes through SFIA,the link prediction Recall and MRR of the target DGNN link decrease by 17.4%and 14.3%respectively,and the accuracy of node classification decreases by 8.7%.

关键词： Dynamic graph neural network Adversarial attack Malicious node Vulnerability

Security defense strategy algorithm for Internet of Things based on deep reinforcement learning

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High-Confidence Computing 2024年第1期4卷 7-13页

作者： Xuecai Feng Jikai Han Rui Zhang Shuo Xu Hui Xia school of Computer science and technology Ocean University of ChinaQingdao 266100China

Currently,important privacy data of the Internet of Things(IoT)face extremely high risks of *** persistently engage in continuous attacks on terminal devices to obtain private data of crucial *** significant progress has been made in recent years in deep reinforcement learning defense strategies,most defense methods still face problems such as low defense resource allocation efficiency and insufficient defense coordination *** solve the above problems,this paper constructs a novel adversarial security scenario and proposes a security game model that integrates defense resource allocation and patrol *** the above game model,this paper designs a deep reinforcement learning algorithm named SDSA to calculate its security defense *** calculates the allocation strategy of the best patrolling strategy that is most suitable for the defender by searching the policy on a multi-dimensional discrete action space,and enables multiple defense agents to cooperate efficiently by training a multi-intelligent Dueling Double Deep Q-Network(D3QN)with prioritized experience ***,the experimental results show that the SDSA-learned security defense strategy can provide a feasible and effective security protection strategy for defenders against attacks compared to the MADDPG and OptGradFP methods.

关键词： Internet of Things Cyber security Deep reinforcement learning Game theory

Lignite-Based Hierarchical Porous C/SiOx Composites as High-Performance Anode for Potassium-Ion Batteries

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Energy & Environmental Materials 2024年第4期7卷 107-117页

作者： Zexu Yang Shouwang Zhao Rongji Jiao Gengyu Hao Yunying Liu Wenxiu He Jingwei Chen Guixiao Jia Jinlong Cui Shaohui Li school of Chemistry and Chemical Engineering Aerogel Functional Nanomaterials Laboratory Inner Mongolia University of Science & Technology school of Materials science and Engineering Ocean University of China school of Materials science and Engineering Zhengzhou University

Silicon oxide （SiOx,0 详细信息

Silicon oxide （SiOx,0

关键词： anode hierarchical porous C/SiOx K4SiO4 lignite potassium-ion batteries

Two-Staged Method for Ice Channel Identification Based on Image Segmentation and Corner Point Regression

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China ocean Engineering 2024年第2期38卷 313-325页

作者： DONG Wen-bo ZHOU Li DING Shi-feng WANG Ai-ming CAI Jin-yan school of Naval Architecture and ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China school of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Identification of the ice channel is the basic technology for developing intelligent ships in ice-covered waters,which is important to ensure the safety and economy of *** the Arctic,merchant ships with low ice class often navigate in channels opened up by *** in the ice channel often depends on good maneuverability skills and abundant experience from the captain to a large *** ship may get stuck if steered into ice fields off the *** this circumstance,it is very important to study how to identify the boundary lines of ice channels with a reliable *** this paper,a two-staged ice channel identification method is developed based on image segmentation and corner point *** first stage employs the image segmentation method to extract channel *** the second stage,an intelligent corner regression network is proposed to extract the channel boundary lines from the channel region.A non-intelligent angle-based filtering and clustering method is proposed and compared with corner point regression *** training and evaluation of the segmentation method and corner regression network are carried out on the synthetic and real ice channel *** evaluation results show that the accuracy of the method using the corner point regression network in the second stage is achieved as high as 73.33%on the synthetic ice channel dataset and 70.66%on the real ice channel dataset,and the processing speed can reach up to 14.58frames per second.

关键词： ice channel ship navigation identification image segmentation corner point regression

Reliability analysis of carbon fiber rod-reinforced umbilical cable under tension using an improved sampling method

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Petroleum science 2024年第4期21卷 2769-2778页

作者： Yu Zhang Hong-Yu Zhang Ran Xia Si-Ao Jiang Fang Wang College of Safety and ocean Engineering China University of Petroleum China Academy of Aerospace Aerodynamics China Aerospace Science and Technology Group College of Engineering science and technology Shanghai Ocean University

The umbilical cable is a vital component of subsea production systems that provide power, chemical agents, control signals et al., and its requirement for reliability is exceedingly high. However, as the umbilical cable is a composite structure comprising multiple functional units, the reliability analysis of such cables involves numerous parameters that can impact calculation efficiency. In this paper, the reliability analysis of a new kind of umbilical cable with carbon fiber rod under tension is analyzed. The global dynamic analytical model is first established to determine the maximum tension load, then the local analytical model of umbilical cable including each unit are constructed by finite element method(FEM). Based on the mechanical analytical model, the reliability of umbilical cable under tension load is studied using response surface method(RSM) and Monte Carlo method. During the calculation process, a new tangent plane sampling method to calculate the response surface function(RSF) is proposed in this paper, which could make sampling points faster come close to the RSF curve, and it is proved that the calculation efficiency increases about 33% comparing with traditional method.

关键词： Umbilical cable Carbon fiber rod Failure analysis Response surface method Reliability