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.

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.

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.

Acidity, Electric Conductivity, Dissolved Oxygen Total Dissolved Solid and Salinity Profiles of Marine Water in Gaza: Influence of Wastewater Discharge

Effects of wastewater discharge on the coastal area in Gaza strip Palestine are not fully investigated. This study investigated the effect wastewater discharge of the physical and chemical properties of marine water in the coastal area over a period of 2 year. Sea water and sediment samples were collected from about 20 different sites. The water and the sediments were collected wastewater/sea water mixing zone at depth 0, 2.5 and 5 m water column depth at a direct wastewater discharging pipe line from different location and similarly from other locations. Water temperature T, electric conductivity (EC), dissolved oxygen (DO), pH, total dissolved solid (TDS) and salinity were determined for water samples using field equipment such as pH-meter, DO meter, TDS-/ and EC-meter. On the other hand, NO3-, SO42-, PO43- were determined in the laboratory using chemical methods, details are described in materials and method section. Results showed average and standard deviation of T, EC, DO, pH, TDS and salinity were 22.02°C ± 4.1°C, EC: 58.41 ± 4.8 ms/cm;DO: 6.96 ± 1.8 mg/L;pH: 7.69 ± 0.37;TDS: 30.51 ± 3.29 and salinity 4.39 ± 0.12 (%);whereas, average and standard deviation of NO3-: were 299.8 ± 204.1 mg/L;SO42-, 5736.9 ± 817.1;and PO43-: 164.35 ± 120.7 mg/L. The measured values indicate significant differences due to high value of standard deviation of some measured parameters. This indicates the influence of wastewater discharge in sea water as shown inside the manuscript in the appropriate section. The study recommends efficient treatment of wastewater and reuses it for agricultural purposes instead of discharging it in sea.

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。

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。

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。

深沪湾末次冰期以来的地层结构及古环境演变

通过深沪湾高分辨率浅地层剖面声学地层和地质钻孔沉积地层的对比,并结合沉积物的粒度、微体古生物以及AMS14C测年的综合分析,揭示了研究区晚更新世末次冰期以来的地层层序,探讨了深沪湾的古环境演变。深沪湾高分辨率浅地层剖面自上而下划分的5个声学地层单元与钻孔岩芯划分的5个沉积地层单元具有较好的对应关系。8.2 ka BP左右,全新世海侵使得海水进入深沪湾海域,海平面低于现今海平面10~12 m,气候凉爽;7 ka BP左右海水到达现今海平面位置,并于6 ka BP左右到达最高,约比现今海平面高2~3 m,气候温暖湿润,这一时期,近岸大量裸子植物被海水淹没并被沉积物快速掩埋;5 850~5 642 a BP研究区温度降低,该降温活动持续到2 ka BP左右,气候凉爽干燥;2 ka BP以来温度逐渐上升,600 a BP左右有一个相对冷期,之后温度又逐渐上升至现今水平。

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。

三种探测技术在舟山港航道扩建工程海底管线探测中的联合应用

海底管线路由探测对航道疏浚施工具有重要意义,而传统的探测技术手段单一,效率较低,无法确定掩埋段信息。为提高海底管线探测结果精度及作业效率,依托宁波舟山港条帚门航道扩建工程项目,综合利用侧扫声呐、浅剖及海洋磁探对工程区域海底管线进行探测:利用侧扫声呐成果作为裸露段海底管线探测结果的基本支撑,浅剖埋深结果与磁探反演埋深结果相互印证,共同提高了海底管线判别的准确性。工程应用结果表明,三种探测技术手段在海底管线探测方面的联合应用成果可靠,探测精度和作业效率显著提升,且具有较好的适用性,在类似项目中具有较好的参考和推广作用。

有缆智能分采技术在多层合采定向井中的应用——以渤海X油田B38井为例

由于衰竭开发,B38井生产2年后储层脱气造成油气干扰,影响该井正常生产。受大斜度、多层段和井段长等井况限制,该井不具备应用“Y”型分采管柱实施测试和控气措施,需要应用新的采油工艺技术。有缆智能分采技术可适用于各种井型,通过地面控制器实现对油井各层段产量、压力和温度等生产参数全过程实时监测及产量调控,同时也为油藏分析、评价和决策提供大量的数据支撑。B38井通过应用该技术,准确判断脱气层段,采取关闭主要产气层段、控制次要产气层段等措施,减缓了油气干扰,恢复了油井正常生产。该技术在渤海油田已经应用10井次,增油效果显著,具有很好的推广价值。

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.

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.

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。