采用解析和数值方法分析浮动式矩形浮箱的波浪诱导载荷研究

A three-dimensional mathematical hydrodynamic model associated with surface wave radiation by a floating rectangular box-type structure due to heave,sway,and roll motions in finite water depth is investigated based on small amplitude water wave theory and linear structural response.The analytical expressions for the radiation potentials,wave forces,and hydrodynamic coefficients are presented based on matched eigenfunction expansion method(MEFEM).The correctness of the analytical results of wave forces is compared with the construction of a numerical model using the open-source boundary element method code NEMOH.In addition,the present result is compared with the existing published experimental results available in the literature.The effects of the different design parameters on the floating box-type rectangular structure are studied by analyzing the vertical wave force,horizontal wave force,torque,added mass,and damping coefficients due to the heave,sway,and roll motions,and the comparison analysis between the forces is also analyzed in detail.Further,the effect of reflection and transmission coefficients by varying the structural width and drafts are analyzed.

预测规则波浪中船舶运动和载荷的频域三维计算机程序

The development of an in-house computer program for determining the motions and loads of advancing ships through sea waves in the frequency domain,is described in this paper.The code is based on the potential flow formulation and originates from a double-body code enhanced with the regular part of the velocity potential computed using the pulsing source Green function.The code is fully developed in C++language with extensive use of the object-oriented paradigm.The code is capable of estimating the excitation and inertial radiation loads or arbitrary incoming wave frequencies and incidence angles.The hydrodynamic responses such as hydrodynamic coefficients,ship motions,the vertical shear force and the vertical bending moment are estimated.A benchmark container ship and an LNG carrier are selected for testing and validating the computer code.The obtained results are compared with the available experimental data which demonstrate the acceptable compliance for the zero speed whereas there are some discrepancies over the range of frequencies for the advancing ship in different heading angles.

RepDNet:A re-parameterization despeckling network for autonomous underwater side-scan sonar imaging with prior-knowledge customized convolution

Side-scan sonar(SSS)is now a prevalent instrument for large-scale seafloor topography measurements,deployable on an autonomous underwater vehicle(AUV)to execute fully automated underwater acoustic scanning imaging along a predetermined trajectory.However,SSS images often suffer from speckle noise caused by mutual interference between echoes,and limited AUV computational resources further hinder noise suppression.Existing approaches for SSS image processing and speckle noise reduction rely heavily on complex network structures and fail to combine the benefits of deep learning and domain knowledge.To address the problem,Rep DNet,a novel and effective despeckling convolutional neural network is proposed.Rep DNet introduces two re-parameterized blocks:the Pixel Smoothing Block(PSB)and Edge Enhancement Block(EEB),preserving edge information while attenuating speckle noise.During training,PSB and EEB manifest as double-layered multi-branch structures,integrating first-order and secondorder derivatives and smoothing functions.During inference,the branches are re-parameterized into a 3×3 convolution,enabling efficient inference without sacrificing accuracy.Rep DNet comprises three computational operations:3×3 convolution,element-wise summation and Rectified Linear Unit activation.Evaluations on benchmark datasets,a real SSS dataset and Data collected at Lake Mulan aestablish Rep DNet as a well-balanced network,meeting the AUV computational constraints in terms of performance and latency.

海上液化天然气行业风险分析研究综述

This research presents a review and classification of the published work related to applied risk analysis and risk management in the maritime liquefied natural gas(LNG)sector from 2000 to 2023.The papers are categorised under two primary contexts.The first is the risk analysis theory context which represents the classification with respect to(w.r.t.)the used risk analysis method,the used risk analysis tool,and the objective of risk analysis,whereas the second is the presented case in the risk analysis context which represents the classification w.r.t.the analysed LNG ship type,the analysed operation,and the inclusion level of human error in risk analysis.The above process has revealed that the interest in this domain of research has increased significantly during the past decade.In addition,the use of dynamic risk analysis(DRA)tools,and the inclusion of human error in the risk analysis model have been observed significantly in the past five years,in particular,for modelling the risk of external LNG transfer operations.It is concluded that the inclusion of the effect of human and organisational factors(HOFs)in risk analysis,and the use of DRA methods for modelling the risk of the daily routine operations of the complex maritime LNG systems can improve the management of the operational risk of these systems.

海上自主水面船舶(MASS)路径跟踪控制系统综述

A review presents the state-of-the-art path-following control systems for maritime autonomous surface ships,where the special focus is placed on the guidance subsystem and control subsystem.The path following control system is one of the basic requirements for autonomous ships since it guarantees that the ship can track the predefined path with small crosstrack errors.The path following problem is firstly defined,and the cross-track error dynamics are derived from the kinematic equations of marine surface ships.The classical guidance laws are introduced,and the governing equations are also presented in this paper.A review of the guidance laws and controllers for the maritime autonomous surface ships has been carried out based on relevant journal and conference papers.Several important properties and characteristics,such as control structure,guidance law,control method,stability,environmental disturbance and vessel dynamics,are defined for the comparative analysis.Finally,the summary and a discussion on the most used technologies for the path following control of marine autonomous surface ships are presented and highlighted.

编者按

The need to reduce the trends associated with climate change imposes measures to reduce the emissions of greenhouse gases to the atmosphere and increase the efficiency of the use of energy.The International Maritime Organization(IMO)has been active since 1997 in promoting the implementation of measures that lead to more efficient ship operation with less fuel consumption and less emissions(Tadros et al.,2023a).The measures include improved ship design and improved operational practices.Several indexes have been created to quantify different aspects of these improvements.The shipping industry has been very actively implementing several actions aiming at the decarbonization of ship operation and more need to continue being implemented.

某散货船单桨、双桨推进系统燃油消耗分析

This paper presents a comparative analysis between single and twin-screw propulsion systems of a bulk carrier to evaluate the ship and propeller performance in terms of fuel consumption as well as to discuss the cavitation and noise criteria.An optimization model is developed to select the optimum propeller geometry and operational point along the engine load diagram for the selected engines of each case.The engines are selected from the same series due to the same behaviour along the engine load diagram.The propellers are selected from the B-series as fixed-pitch propellers.It has been concluded that while the components of the single-screw propulsion system are larger than the twin-screw,the single-screw propulsion system shows a reduction in fuel consumption than the twin screw by around 19%,thus affecting the amount of exhaust emissions from the ship.This model helps the ship designers to select a suitable propeller to improve the energy efficiency of the ships.

国际海事组织船舶能效提案及其影响综述

This paper presents a review of the different International Maritime Organization(IMO)initiatives to improve the ship energy efficiency of new and existing ships,which is considered one of the essential tasks to reduce Greenhouse Gas(GHG)in the maritime industry.First,the IMO effort and initiatives and the different indices suggested by the IMO are presented till the last version of the Marine Environment Protection Committee(MEPC),showing the effect of different technologies on reducing the level of indices and the suggested improvement of the terms of indices in the next years.Second,the short-and long-term strategies suggested by the IMO are presented,showing that the effect of indices will be noticed in the short term,while the new fuels will show a significant improvement in the long term.Finally,several examples of cooperation between the different organizations are presented,showing that transferring knowledge and experience will significantly impact the maritime industry and thus lead to the concept of green ships in the near future.This paper shows that the combination of different solutions,the cooperation between stakeholders and the sharing of the data and information are important to achieve the required goal.

物理生成的长峰不规则波的非高斯统计特性

An experimental study is presented on the non-Gaussian statistics of random unidirectional laboratory wave fields described by JONSWAP spectra.Relationships between statistical parameters indicative of the occurrence of largeamplitude waves are discussed in the context of the initial steepness of the waves combined with the effect of spectral peakedness.The spatial evolution of the relevant statistical and spectral parameters and features is also considered.It is demonstrated that over the distance the spectra exhibit features typical for developing nonlinear instabilities,such as spectral broadening and downshift of the peak,along with lowering of the high-frequency tail and decrease of the peak magnitude.The wave fields clearly show an increase of third-order nonlinearity with the distance,which can be significant,depending on the input wave environment.The steeper initial conditions,however,while favouring the occurrence of extremely large waves,also increase the chances of wave breaking and loss of energy due to dissipation,which results in lower extreme crests and wave heights.The applied Miche-Stokes-type criteria do confirm that some of the wave extremes exceed the limiting individual steepness.Eventually,this result agrees with the observation that the largest number of abnormal waves is recorded in sea states with moderate steepness.

极端海浪对LNG运输船影响的试验研究

This paper presents a comprehensive experimental study on the effect of extreme waves on a LNG carrier.The LNG carrier model was equipped with a variety of sensors to measure motions,green water height on deck as well as local and global loads.Experiments in transient wave packets provided the general performance in waves in terms of response amplitude operators and were accompanied by tests in regular waves with two different wave steepness.These tests allowed detailed insights into the nonlinear behavior of the vertical wave bending moment in steep waves showing that green water on deck can contribute to a decrease of vertical wave bending moment.Afterwards,systematic model tests in irregular waves were performed to provide the basis for statistical analysis.It is shown that the generalized extreme value distribution model is suitable for the estimation of the extreme peak values of motions and loads.Finally,model tests in tailored extreme wave sequences were conducted comparing the results with the statistical analysis.For this purpose,analytical breather solutions of the nonlinear Schrödinger equation were applied to generate tailored extreme waves of certain critical wave lengths in terms of ship response.Besides these design extreme waves,the LGN carrier was also investigated in the model scale reproduction of the real-world Draupner wave.By comparing the motions,vertical wave bending moment,green water column and slamming pressures it is concluded that the breather solutions are a powerful and efficient tool for the generation of design extreme waves of certain critical wave lengths for wave/structure investigations on different subjects.

Rolling Bearing Fault Diagnosis Based On Convolutional Capsule Network

Fault diagnosis technology has been widely applied and is an important part of ensuring the safe operation of mechanical equipment.In response to the problem of frequent faults in rolling bearings,this paper designs a rolling bearing fault diagnosis method based on convolutional capsule network(CCN).More specifically,the original vibration signal is converted into a two-dimensional time–frequency image using continuous wavelet transform(CWT),and the feature extraction is performed on the two-dimensional time–frequency image using the convolution layer at the front end of the network,and the extracted features are input into the capsule network.The capsule network converts the extracted features into vector neurons,and the dynamic routing algorithm is used to achieve feature transfer and output the results of fault diagnosis.Two different datasets are used to compare with other traditional deep learning models to verify the fault diagnosis capability of the method.The results show that the CCN has good diagnostic capability under different working conditions,even in the presence of noise and insufficient samples,compared to other models.This method contributes to the safe and reliable operation of mechanical equipment and is suitable for other rotating scenarios.

船舶AIS轨迹快速自适应谱聚类算法

为了对船舶AIS轨迹数据进行快速聚类,本文提出了一种基于Hausdorff距离的船舶轨迹快速自适应谱聚类算法(fast self-tune spectral clustering,FSSC)。在保留轨迹特征的情况下,利用Douglas-Peucker(DP)算法对船舶轨迹数据进行预处理;基于Hausdorff距离,设计自动选取尺度参数的相似度度量函数,构造相似度矩阵并采用谱聚类算法对船舶轨迹进行聚类。以长江口水域船舶实际AIS数据为样本对算法进行了验证,结果表明:聚类结果能够准确提取水域船舶主要航路,算法消耗系统资源少,计算速度快。该方法对水域船舶主要航路识别,提高海事监管效率等方面具有参考意义。

桥梁防船撞钢套箱的碰撞力快速估算

研究船舶与单墩桥梁防撞钢套箱艏尖舱的碰撞过程,探讨碰撞力快速估算及防撞装置模块化设计的可行性。首先采用非线性有限元方法模拟1 000吨级三峡标准散货船与钢套箱式桥梁防船撞装置的碰撞过程,分析了防撞钢套箱艏尖舱在不同的斜边角和船舶碰撞速度下的能量吸收特性以及传递至桥墩的碰撞力特性,得到的结果可为防撞钢套箱外形的选择提供参考。对所选择的防撞钢套箱形式,采用Boltzmann函数拟合了撞击船速与桥梁所受横桥向及顺桥向碰撞力之间的关系,该拟合公式可以用于此类防撞钢套箱方案设计阶段的撞击力快速估算。

散货船与桥墩碰撞力的经验公式与数值模拟对比研究

介绍了目前几种常见的船桥碰撞力估算公式,并采用这些公式分别计算了四艘三峡标准散货船在各种航速下撞击桥墩的碰撞力。根据三峡标准散货船的设计图纸建立船体有限元模型,通过数值模拟计算了不同吨级、船速下的船桥碰撞力曲线。在桥梁设计时,该曲线可以为该类船舶一桥墩碰撞力计算及评估提供参考。结合经验公式的推导过程,通过船桥碰撞力经验公式与有限元数值仿真分析计算结果表明,铁路桥涵设计规范的船桥碰撞力公式更适合于斜艏500至3 000 t级散货船,而美国公路桥梁设计规范的船桥撞击力计算公式对该类型吨级船舶的碰撞力结果偏大。

中国区域生态建设协调度评价及提升——基于能源技术专利数据

不断深化的工业化和城市化使中国化石能源消耗处于扩展期。日益增加的化石能源消耗尽管带来了快速的经济发展,但也使中国面临着日益严重的资源环境问题。而随着经济发展水平的不断提高,人们对生活质量的要求越来越高,并逐渐成为社会主要矛盾的重要体现。在另一方面,受区域技术、经济等因素影响,区域生态建设绩效出现了加大的差异。尽管国家采取了一系列政策来促使区域生态建设协调程度,但区域差异现象依然明显。在这种情况下,中央提出建设美丽中国来满足各地区人们对高质量生活的向往。结合现有研究结论来看,要想建设美丽中国、实现区域平衡发展,就必须提高区域生态建设协调程度。而要真正实现区域生态建设协调发展,就必须通过能源技术创新提高区域能源效率改善区域生态水平。基于上述分析,文章在基于能源约束程度对内陆省市进行区域划分基础上,运用DEA方法评价了区域生态建设协调度,分析了能源技术专利总量对区域生态建设协调度的影响,讨论了区域生态建设协调度提升途径。结论显示:①中国区域生态建设协调度在不断提高但总体水平不高,且与能源约束程度成正比。②能源技术专利是区域生态建设协调程度不断提高的重要动力,区域生态建设协调程度与专利总量成正相关关系;但区域推动作用差异明显,其大小取决于区域能源消费特征与专利结构。可从以下方面提高区域生态建设协调程度:扩大能源技术研发规模,优化能源技术研发投入和专利结构;控制能源消费总量,实现能源消费结构的低碳化;加强政策体系建设,充分发挥政策工具的创新诱导作用。

二苯甲酮结晶热力学性质及其模型研究

采用静态法测定了常压下在278.15~313.15 K温度范围内二苯甲酮在不同配比的甲醇-乙腈混合溶剂中的溶解度数据。实验结果表明,当溶剂组成固定时,二苯甲酮的溶解度随温度的升高而增大;同时,二苯甲酮在甲醇-乙腈混合溶剂中存在潜溶现象。此外,分别使用改进的Apelblat方程和λh方程拟合二苯甲酮的溶解度实验数据,结果表明2种模型均能取得较好拟合效果。最后,基于NRTL模型和实验获得的溶解度数据,计算并分析了二苯甲酮的混合和溶解过程的热力学性质。二苯甲酮溶解度的测定与关联能够为其结晶工艺的开发提供重要的理论依据。

Computation of Ship Hydrodynamic Interaction Forces in Restricted Waters using Potential Theory

A computer code based on the double-body potential flow model and the classic source panel method has been developed to study various problems of hydrodynamic interaction between ships and other objects with solid boundaries including the seabed. A peculiarity of the proposed implementation is the application of the so-called ＂moving-patch＂ method for simulating steady boundaries of large extensions. The method is based on an assumption that at any moment just the part of the boundary （＂moving patch＂） which lies close to the interacting ship is significant for the near-field interaction. For a specific case of the fiat bottom, comparative computations were performed to determine optimal dimensions of the patch and of the constituting panels based on the trade-off between acceptable accuracy and reasonable efficiency. The method was applied to estimate the sway force on a ship hull moving obliquely across a dredged channel. The method was validated for a case of ship-to-ship interaction when tank data were available. This study also contains a description of a newly developed spline approximation algorithm necessary for creating consistent discretizations of ship hulls with various degrees of refinement.

Optimization of the Performance of Marine Diesel Engines to Minimize the Formation of SO_x Emissions

Optimization procedures are required to minimize the amount of fuel consumption and exhaust emissions from marine engines.This study discusses the procedures to optimize the performance of any marine engine implemented in a 0D/1D numerical model in order to achieve lower values of exhaust emissions.From that point,an extension of previous simulation researches is presented to calculate the amount of SOx emissions from two marine diesel engines along their load diagrams based on the percentage of sulfur in the marine fuel used.The variations of SOx emissions are computed in g/k W·h and in parts per million(ppm)as functions of the optimized parameters:brake specific fuel consumption and the amount of air-fuel ratio respectively.Then,a surrogate model-based response surface methodology is used to generate polynomial equations to estimate the amount of SOx emissions as functions of engine speed and load.These developed non-dimensional equations can be further used directly to assess the value of SOx emissions for different percentages of sulfur of the selected or similar engines to be used in different marine applications.

CFD Analysis of Ship-to-Ship Hydrodynamic Interaction

A numerical study of ship-to-ship interaction forces is performed using a commercial CFD code,and the results are compared with experimental data and with the results of a panel method analysis.Two ship models have been used in the interaction forces analysis:a tug and a tanker,advancing parallel to each other with different lateral distances and two different values of the fluid depth.Computations are carried out with four different flow models:inviscid and viscous flow with the free surface modeled as a rigid wall and inviscid and viscous flow with the deformable free surface.A fair agreement was obtained with available experimental data and results obtained by panel method.The influence of viscosity in the computations is found to be comparatively weak,while the wavemaking effects may be important,at small magnitude of the horizontal clearance.

Review of Condition-Based Maintenance Strategies for Offshore Wind Energy

The existing maintenance strategies of offshore wind energy are reviewed including the specific aspects of condition-based maintenance, focusing on three primary phases, namely, condition monitoring, fault diagnosis and prognosis, and maintenance optimization. Relevant academic research and industrial applications are identified and summarized. The state of art, capabilities,and constraints of condition-based maintenance are analyzed. The presented research demonstrates that the intelligent-based approach has become a promising solution for condition recognition, and an integrated data platform for offshore wind farms is significant to optimize the maintenance activities.