Facial Features of an Air Gun Array Wavelet in the Time-Frequency Domain Based on Marine Vertical Cables

Air gun arrays are often used in marine energy exploration and marine geological surveys.The study of the single bubble dynamics and multibubbles produced by air guns interacting with each other is helpful in understanding pressure signals.We used the van der Waals air gun model to simulate the wavelets of a sleeve gun of various offsets and arrival angles.Several factors were taken into account,such as heat transfer,the thermodynamically open quasi-static system,the vertical rise of the bubble,and air gun post throttling.Marine vertical cables are located on the seafloor,but hydrophones are located in seawater and are far away from the air gun array vertically.This situation conforms to the acquisition conditions of the air gun far-field wavelet and thus avoids the problems of ship noise,ocean surges,and coupling.High-quality 3D wavelet data of air gun arrays were collected during a vertical cable test in the South China Sea in 2017.We proposed an evaluation method of multidimensional facial features,including zeropeak amplitude,peak-peak amplitude,bubble period,primary-to-bubble ratio,frequency spectrum,instantaneous amplitude,instantaneous phase,and instantaneous frequency,to characterize the 3D air gun wave field.The match between the facial features in the field and simulated data provides confidence for the use of the van der Waals air gun model to predict air gun wavelet and facial features to evaluate air gun array.

Dynamic Motion and Tension of Marine Cables Being Laid During Velocity Change of Mother Vessels

Flexible segment model （FSM） is adopted for the dynamics calculation of marine cable being laid. In FSM, the cable is divided into a number of flexible segments, and nonlinear governing equations are listed according to the moment equilibriums of the segments. Linearization iteration scheme is employed to obtain the numerical solution for the governing equations. For the cable being laid, the payout rate is calculated from the velocities of all segments. The numerical results are shown of the dynamic motion and tension of marine cables being laid during velocity change of the mother vessels.

Experimental Study on the Influence of Cross-Section Type of Marine Cable Conductors on the Bending Performance

Through the development of marine energy,marine cables are the key equipment for transmission of electrical energy between surface platforms and underwater facilities.Fatigue failure is a critical failure mode of marine cables.The bending performance of the cable conductor has a major influence on both bending and fatigue performances of the overall cable structure.To study the influence of different types of the conductor cross-section on the bending performances of marine cable conductors,three types of copper conductors with the same cross-sectional area,i.e.,noncompressed round,compressed round,and shaped wire conductors,were selected.The experimental results demonstrated that the cross-section type significantly affects the bending performances of copper conductors.In particular,the bending stiffness of the shaped wire conductor is the highest among the three conductor types.Four key evaluation parameters,i.e.,the bending stiffness,maximum bending moment,envelope area,and engineering critical slip point,were selected to compare and analyze the bending hysteresis curves of the three copper conductors.The differences in the key evaluation parameters were analyzed based on the structural dimensional parameters,processing methods,and classical bending stiffness theoretical models of the three copper conductor types.The results provide an important theoretical guidance for the structural design and engineering applications of marine cable conductors.

Steady-State Configuration and Tension Calculations of Marine Cables Under Complex Currents via Separated Particle Swarm Optimization?

Under complex currents, the motion governing equations of marine cables are complex and nonlinear, and the calculations of cable configuration and tension become difficult compared with those under the uniform or simple currents. To obtain the numerical results, the usual Newton-Raphson iteration is often adopted, but its stability depends on the initial guessed solution to the governing equations. To improve the stability of numerical calculation, this paper proposed separated the particle swarm optimization, in which the variables are separated into several groups, and the dimension of search space is reduced to facilitate the particle swarm optimization. Via the separated particle swarm optimization, these governing nonlinear equations can be solved successfully with any initial solution, and the process of numerical calculation is very stable. For the calculations of cable configuration and tension of marine cables under complex currents, the proposed separated swarm particle optimization is more effective than the other particle swarm optimizations.

An Overview of Structural Design,Analysis and Common Monitoring Technologies for Floating Platform and Flexible Cable and Riser

Offshore oil and gas development plays an important part in the global energy sector.Offshore platforms and flexible pipes are the key equipments in the whole offshore oil and gas development system.Because of the randomness and uncertainty of wave and current loads in the ocean environment,the structural design and mechanical analysis of the marine equipment can be highly complicated.Therefore,this paper reviews the recent works of the theoretical model,numerical simulation,and experimental test in three research areas:hydrodynamic analysis of offshore platforms,structural mechanics analysis of flexible pipe and cable,and monitoring technology of offshore floating structures under marine loads.By analyzing their main research methods and key technical difficulties,this paper provides theoretical basis and technical support for the reliability engineering application of offshore platforms and flexible pipelines.Also,China is relatively backward in the design of marine floating platform,the design,analysis and testing of flexible pipeline and cable,as well as the marine equipment prototype monitoring technology research.Calling for breakthroughs at the earliest possible stage in the above fields,prime research should be focused on and strategic planning should be made to deal with“key areas and stranglehold problems”.It is of great significance for the development of China's deep-sea energy and resource development of independent technology and on time to achieve the“carbon peak”national strategic objectives.

基于开放海缆通信系统的海缆登陆站优化研究

国际互联网带宽的快速增长推动了海底光缆及海缆登陆站的加速建设需求。分析了我国内地海缆登陆站的当前布局及其在未来需求的不足,并结合开放海缆通信系统的发展趋势,研究了将海缆传输终端设备从传统的海缆登陆站转移到核心机房的技术和经济可行性。最后,在此基础上提出了海缆登陆站优化部署的建议。

船舶电缆敷设辅助设计系统电缆册模块二次开发

依据AM软件的可扩展性,以船舶电缆敷设辅助设计系统为基础开发电缆册模块。论述电缆册模块的界面与功能,分析电缆册模块的开发环境、设计需求和功能实现,并进行实例验证。结果表明,电缆册模块可提高电缆册信息的完整度与准确度,并为船厂信息化提供数据接口。

拖曳系统中瑞利阻尼系数变化在回转过程中对拖缆动力学振动响应的影响

海洋拖曳系统是典型的刚柔多体系统。需要指出的是,到目前为止,绝大多数的关于海洋拖曳缆体系统的动力学问题研究都没有非常充分地考虑到阻尼的作用。但在海洋拖曳系统的结构动力学分析中,特别是拖缆回转过程中的动态响应分析中,阻尼的作用是不可忽略的。且由于阻尼的存在,拖缆的模态特性也会呈现出高度的复杂性。为探究瑞利阻尼在拖缆回转过程中的影响,基于凝集质量法对瑞利阻尼的在拖缆系统中的表达形式进行了进一步的整理与分解,并对各个阻尼分量的影响进行了归纳总结,得到了一些较为通用性的结论,对于实际海上拖曳作业有一定的指导意义。

海洋探测装备收放缆力学性能研究综述

收放缆是维系海底探测装备与船舶的唯一纽带,具备电力、信息传输以及承重等功能,被广泛用于各类收放系统。收放缆的安全可靠性是其核心功能要求,因此开展收放缆力学性能试验是整个收放缆研究的基础。从海洋绞车以及收放缆的种类、失效形式出发,系统总结了收放缆力学性能试验研究动态,展望其未来研究方向。对海洋绞车以及收放缆进行了功能分类并详细分析了收放缆失效的形式以及原因;阐述了收放缆服役环境工况及其力学性能要求与试验研究现状;探讨海洋探测装备收放缆的力学性能研究方向,从极端服役环境对合成纤维收放缆力学性能影响及其机制、多重载荷耦合作用下合成纤维收放缆破坏行为及其机理、收放缆力学性能技术与综合模拟装置等方面进行了展望。

电驱动海洋绞车自动排缆控制系统建模与仿真

为了克服海洋环境下作业绞车时常出现空槽、乱缆、夹缆等排缆故障,综合考虑海浪、负载、缆绳、摩擦等因素,并通过缆绳张力引入外部干扰,建立起电驱动海洋绞车自动排缆控制系统数学模型,仿真分析了排缆丝杆转速响应,结果表明:海洋绞车运行过程中外部环境、绞车自身特性的变化,致使排缆丝杆转速的幅值、周期发生变化,易出现排缆误差,为电驱动海洋绞车自动排缆协同控制提供了理论支撑。

论国家对海底电缆和海底管道的投资保障义务与中国因应

作为通讯和能源传输领域的基础设施,海底电缆和海底管道的重要性得到了国际社会的广泛承认。由于私人投资者控制着绝大部分海底电缆和管道,因此国际投资法对海底电缆和管道保障具有无法替代的现实作用,《联合国海洋法公约》等亦为投资保障的落实提供了部分国际法层面的依据。然而因海底电缆和管道自身的独特跨界属性,以及国际法和各国国内法就海底电缆和管道法律制度供给的短缺,使得海底电缆和管道能否获得国际投资协定(IIAs)的保障,以及东道国对海底电缆和管道肩负哪些具体保障义务,均存在较大的不确定性。中国应重视国际投资法与海底电缆和管道保障的其他法律规则之间的联动关系,并以此为基础在现有国际投资协定、国际法和各国国内法与规则中就海底电缆和管道作出针对性的法律制度设计,以实现对海底电缆和管道的有效保障。

海洋大气自然环境下电连接器线缆密封措施验证分析

研究海洋大气环境下,电连接器线缆不同密封工艺方法的环境适应性。试验选取航空常用的GJB599系列圆形连接器,实施4种不同的线缆密封防护措施,在某南海环境自然暴晒站开展了3年自然环境暴露试验,通过电连接器的绝缘电阻和耐电压测试结果的变化,验证不同线缆密封防护工艺的环境适应性。试验结果与试验室模拟海洋环境的加速试验存在一定偏差,通过原因分析和对试验结果的综合评估,给出工程应用上给出了一些实用的建议。

穿越工程中海缆拖拉力学仿真分析

在水平定向钻配合穿越的海缆铺设工程里,海缆拖拉穿越海缆套管的过程中海缆与钢制管道之间的摩擦随着进入套管距离变大而不断增加,当海缆所受的最大牵引力大于最大允许拉力时,将造成海缆的机械损坏。本文对海缆拖拉过程进行了理论分析和计算,并通过有限元仿真模拟了海缆拖拉的过程,实现了对海缆拖拉机械损伤分析和预测。

一种水下机器人用海洋脐带缆的研制

为了满足水下机器人与水面控制系统的电力传输、信号传输和音/视频传输等需求,文中介绍了一种水下机器人用海洋脐带缆。通过结构设计、材料选型、制造工艺、计算分析、关键参数设计和测试方法的确定,对脐带缆的机械性能、环境性能和电气性能进行实测。结果表明,脐带缆的实测值与设计要求相符,具有抗拉力强、耐海水腐蚀、耐盐雾性、防生物侵袭等特点,满足电源线与音/视频线兼容、柔软性好的要求。

基于神经网络的风电海缆弯曲限制器优化设计

我国海上风力发电已进入平价并网时代,行业中所有零部件设计都将面临优化设计的挑战。弯曲限制器广泛应用于风电缆保护中,其弯曲刚度与Mises峰值应力都是结构设计的关键指标。目前,弯曲限制器结构优化设计多基于经验和有限元分析迭代,该方法效率较低,并且多目标优化较困难。本文针对该问题提出一种基于神经网络的风电海缆弯曲限制器多目标优化方法。先在给定的设计域内,利用正交试验设计法和有限元分析获得的样本,构建RBF神经网络代理模型;再采用非支配排序遗传算法IⅡI(NSGA-IⅡI)对弯曲限制器进行多目标优化,得到了Pareto最优解集。本文为限弯器结构结构设计提供了一种可行的多目标优化方法。

Numerical Investigation of the Dynamics for Low Tension Marine Cables

This paper presents a numerical investigation into the dynamics of marine cables which are extensively used in offshore industry. In this numerical study, the Euler-Bernoulli beam model is adopted to develop the governing equations of the cable. Bending stiffness is considered to cope with the low tension problem in local area of towing cable, and thus a more accurate solution with the consideration of the axial elongation can be given.The derived strongly-coupled and nonlinear governing equations are solved by a second-order accurate, implicit,and large time step stable central finite difference method. The quadratically convergent Newton-Raphson iteration method is applied to solving the discrete nonlinear algebraic equations. Then a towed array sonar system(TASS)problem is studied. The numerical solutions agree reasonably well with the experimental data and the simulated results of the references. The specified program of the present paper shows great robustness with high efficiency.

有缆海底观测系统进展及发展建议

有缆海底观测系统具备长期、原位、在线观测的技术优点,在海洋基础科学研究、资源与能源勘探开发利用、海洋灾害预报预警、海洋环境保护、航海与军事海洋环境保障等方面有广泛应用。阐述和总结了国内外有缆海底观测系统发展现状,分析了有缆海底观测系统关键技术、应用场景和数据衍生服务,从有缆海底观测系统顶层设计、创新发展、差异化研发,以及拓展有缆海底观测数据应用领域等方面提出了未来发展的具体建议,以期对我国海底观测系统的发展提供有益的借鉴。

船舶电缆敷设辅助设计系统

利用AVEVA Marine平台的可扩展性,在电缆敷设设计功能中增加电缆通道类型、电缆通道容量和避碰区域等约束条件,对电缆铺设设计功能进行优化。运用C#高级编程语言和改进的Dijkstra算法对AVEVA Marine软件船舶电缆敷设设计功能进行二次开发,实现对船舶电缆路径的高效辅助设计,在提高电缆敷设效率的同时,减少电缆敷设带来的资源浪费。

海洋拖缆平衡位形及振动特性影响因素研究

海洋拖缆地震勘探系统是海洋石油勘探的主要设备。水下拖缆在工作时受到重力、浮力、流体力和两端集中力的作用,当拖曳速度稳定时会呈现稳定的平衡位形。本文采用集中质量法对拖缆的平衡位形进行预测,研究单位长度拖缆质量、拖体质量、拖缆阻力系数、拖体阻力系数和拖曳速度对拖缆平衡位形的影响,研究发现拖缆的平衡位形可以分为“上凸”形、“下凹”形和“直线”形三类,采用理论推导讨论拖缆呈现三种平衡位形的内在机理。最终研究不同参数对拖缆固有频率的影响,揭示拖缆固有频率与平衡位形、张力和单位长度拖缆质量的关系。

海工装备系泊缆索拉力监测技术与装置研究

目的 研究缆索拉力的实时监测技术和装置,以保障海工装备的系泊安全。方法 以导向滑轮的主承力构件滑轮轴为研究对象,在保证结构强度的前提下,对滑轮轴结构进行改造,研制缆索拉力监测新结构新装置,将求解大径长比滑轮轴剪力问题转化为测量局部特征点的单向变形,并通过实尺度试验得到标定系数,间接推算缆索拉力,将试验数据与有限元计算结果进行对比,验证监测方法的可行性和精确度。结果 经过仿真分析与试验标定表明,滑轮轴特征点的变形与缆索拉力之间存在线性关系,以缆索拉力280 kN为界,可分段线性拟合缆索拉力标定系数,测点1系数为0.312 4和0.137 6,测点2系数为0.2699和0.098 2。结论 本文研究的监测技术和装置能够较为准确地监测海工装备系泊缆索的实时拉力,兼具高可靠性、低成本、易实施的特点。