An investigation of roll characteristics of two full scale ships at sea

Random roll responses measured during the sea trials of two Canadian Coast Guard search and rescue vessels have been analysed using an innovative approach. This approach comprises the use of a combination of the random decrement technique, a neural network algorithm and mathematical modelling. Roll characteristics are found to vary randomly. Estimates of the mean values and the variances of the parameters were obtained and their variation with forward speed has been discussed.     

基于遗传算法的开敞域码头桩基优化设计

利用遗传算法对大型高桩码头的桩基布置问题建立了离散结构优化模型,通过对上海宝钢30万吨码头桩基优化的算例分析,得到了较常规算法更好的结构方案。     

基于多阶段贝叶斯网络法的脐带缆全寿命周期可靠性分析

脐带缆是深海油气开发的关键设备之一,主要由钢管单元、电缆单元、光缆单元、护套及铠装单元组成。脐带缆在全寿命周期经过设计制造、储存、安装、在位运行、修复阶段,其每个阶段的可靠性并不是某个常数,而是随时间变化的函数,因此有必要对脐带缆全寿命周期可靠性的变化进行分析。建立某气田水下脐带缆在储存、安装、在位运行阶段的故障树模型,将其转化为多阶段贝叶斯网络模型进行建模分析,基于OREDA手册数据,假设部件寿命服从指数分布,对脐带缆存储、安装、在位运行阶段的可靠性进行分析,得到不同阶段脐带缆可靠性的变化曲线,并与可靠性框图方法进行对比分析。同时,通过引入条件可靠性对该方法进行了优化,分析脐带缆修复后的可靠性变化,以及对脐带缆关键部件进行重要度分析,针对薄弱环节提出改进措施。可靠性分析可为水下脐带缆的安全运行提供技术支持,同时也为海洋结构与设备的全寿命周期可靠性分析提供了一种方法参考。     

基于GPS实测数据和PS-InSAR技术的北极Pedersenbreen冰川表面运动特征分析

Pedersenbreen冰川是我国北极冰川运动监测的重点研究区域之一。本文以2017年9月—2018年9月的共31景Sentinel-1A中等分辨率SAR影像数据为基础,采用PS-InSAR技术对Pedersenbreen冰川进行长时间序列的形变监测,获取Pedersenbreen冰川沿雷达视线方向的运动速率图,提取Pedersenbreen冰川沿雷达视线方向的运动信息。研究发现,Pedersenbreen冰川整体处于向下游运动的趋势,Pedersenbreen冰川主体的运动速率范围为-8.901～-2.957 m/a。将冰川运动速率沿铅垂线方向进行分解,得到GPS监测点P1、P2、P3、P4、P5缓冲区的冰川表面垂直变化速率均值,分别为-2.316 1 m/a、-2.438 7 m/a、-1.851 7 m/a、-2.181 1 m/a和-1.875 4 m/a。基于GPS实测数据进行处理,获得冰川表面垂直变化速率分别为-1.879 6 m/a、-2.041 3 m/a、-1.422 0 m/a、-1.722 3 m/a和-1.376 9 m/a,误差均在0.5 m/a之内,验证了结果的可靠性。表明PS-InSAR技术可以用于极地冰川运动趋势的变化监测,是冰川监测手段的一个有效补充。     

高桩防撞墩动力大变形分析及防撞设计新方法

通过引入合理的船舶与防撞墩相互作用模型及桩基动力p-y曲线法,建立船舶撞击高桩防撞墩的动力学分析模型。通过分析撞击系统的动力响应及能量转移规律发现,撞击过程中水平变形性能较好的高桩通过水平大变形而吸收大部分撞击能量,此时高桩破坏以桩身最大弯矩作为控制标准;船首强度、混凝土防撞墩总质量及桩周土强度参数对撞击过程中桩身最大弯矩影响不大。传统水上结构防撞设计方法不再适于这类刚度较小结构的防撞设计,通过对比分析,提出了工程上适用的基于能量控制的防撞设计新方法。     

Research on shaft resistance of rock-socketed piles based on the cavity expansion theory

The shaft resistance of rock-socketed piles depends not only on the properties of its surrounding rock, but also on the radial force induced by the load imposed on the top of the pile. This paper deduced a plastic zone of rock around a single pile and obtained the shaft resistance of a rock-socketed pile based on the theories of cavity expansion and shear strength. The research results showed that the magnitude of the radial force in the socketed portion of a rock-socketed pile was related to the pile diameter, Poisson’s ratio, and properties of the surrounding rock. The influence area of rock decreased with increasing pile diameter. The radial force and lateral friction decreased with the increasing relative stiffnesses of the pile and rock. The radial stress on the elastic–plastic interface can be analytically determined based on the rock properties and depth. A field test was used to validate the proposed method, and a good agreement was obtained between the field data and predicted results of the proposed method. The research results in this paper are beneficial to guide actual practice.     

基于SAR的海上溢油监测最佳探测参数分析

基于SAR数据,在后向散射系数计算的基础上,从波段、极化方式、入射角等方面开展了海上溢油监测参数分析,结果表明:基于SAR的海上溢油监测,从波段分析,X波段与C波段较L波段更适合监测海上溢油;从极化方式分析,VV极化较HH,HV极化更适合监测海上溢油;从入射角分析,在计算溢油与海水临界值时,经多次实验,位于远入射角的疑...     

基于元胞自动机的6因子海洋溢油模型

本文采用三维元胞自动机模型,对风流、水流等水平方向的影响系数进行了改进,另外考虑了蒸发、垂直扩散等垂直方向的影响,以及岸边附着、溶解等因子,并且引入乳化含水率将乳化因子进行实际量化,构建了6因子海洋溢油模型。并以“DeepSpill”的溢油试验为基础进行了模拟,Kappa系数达到0.902,模拟结果与实际具有极好的一致性。     

Premature refusal of large-diameter,deep-penetration piles on an offshore platform

Open-ended pipe piles are commonly driven into the seabed to support offshore platforms. This paper presents a case of practical offshore driven pile installation experiences associating with premature refusal. Pile drivability and capacity are analyzed using sufficient driving records. Dynamic loading tests were performed three months after the driving in order to determine the pile capacity after refusal. The test results are detailed in this paper compared with back analysis of measured pile driving records. Empirical equations are provided to predict soil resistance during driving and after setup according to the driving records and dynamic loading tests. Analyzing this practical engineering case is hoped to lead to a better understanding of pile driving, especially when premature refusal occurs. The sufficient details of the engineering data in this paper are also expected to enrich the engineering experience and literature of offshore piles in offshore engineering.     

基于元胞自动机的海上溢油扩散模拟

利用逻辑回归算法和决策树C5.0算法分别获取溢油扩散的转换规则,并构建了基于逻辑回归的CA模型和决策树CA模型。这两个模型仅需要设置起始影像、影响因子和权重等少数的变量,便可以方便地模拟出溢油的动态变化情况。把逻辑回归CA模型和决策树CA模型应用到Deep Spill项目的海上溢油模拟实验,结果表明逻辑回归CA模型的模拟总精度达到96.4%,Kappa系数达0.893,而决策树CA模型的模拟结果更为理想,其精度和kappa系数分别提高了0.2%和0.006。利用元胞自动机能够很好地模拟并预测出海上溢油的动态变化,可以满足对溢油快速响应的要求。     

基于海面多普勒谱模型的海浪反演精度分析

Microwave remote sensing is one of the most useful methods for observing the ocean parameters. The Doppler frequency or interferometric phase of the radar echoes can be used for an ocean surface current speed retrieval,which is widely used in spaceborne and airborne radars. While the effect of the ocean currents and waves is interactional. It is impossible to retrieve the ocean surface current speed from Doppler frequency shift directly. In order to study the relationship between the ocean surface current speed and the Doppler frequency shift, a numerical ocean surface Doppler spectrum model is established and validated with a reference. The input parameters of ocean Doppler spectrum include an ocean wave elevation model, a directional distribution function, and wind speed and direction. The suitable ocean wave elevation spectrum and the directional distribution function are selected by comparing the ocean Doppler spectrum in C band with an empirical geophysical model function(CDOP). What is more, the error sensitivities of ocean surface current speed to the wind speed and direction are analyzed. All these simulations are in Ku band. The simulation results show that the ocean surface current speed error is sensitive to the wind speed and direction errors. With VV polarization, the ocean surface current speed error is about 0.15 m/s when the wind speed error is 2 m/s, and the ocean surface current speed error is smaller than 0.3 m/s when the wind direction error is within 20° in the cross wind direction.     

基于层次分析法的沿海省市海洋科技竞争力比较与分析

近年来沿海各省市都制定了自己的“海洋强省战略”,海洋科技实力作为海洋强省战略中一个独立要素,必将发挥越来越重要的作用。对沿海11省市海洋科技综合实力进行比较分析,有助于各省市对自身实力有更加准确地把握,为今后的工作重点提供科学的依据,从而制定更加完备准确的发展战略和政策。     

Assessment of typhoon storm surge disaster scale based on expansion model

The South China Sea suffers strongly from the typhoon storm surge disasters in China, and its northern coastal areas are facing severe risks. Therefore, it is necessary and urgent to establish an assessment system for rating typhoon storm surge disaster. We constructed an effective and reliable rating assessment system for typhoon storm surge disaster based on the theories of over-threshold, distribution function family, and composite extreme value. The over-threshold sample was used as the basi...     

基于多目标决策模型的如东近岸浅滩适宜围填规模研究

适宜的围填海规模能够最大限度的协调岸滩围填和海洋资源环境保护的关系。以江苏辐射沙脊海域如东近岸浅滩围填海为例,运用多目标决策理论与方法,综合考虑围填海对动力泥沙环境、海洋生态环境、资源综合开发和社会经济影响,建立围填海适宜规模评价指标体系,构建适宜围填规模评价决策模型。并对该岸段不同的围填规模方案进行计算,据此推荐围堤前沿线位于+5 m的围填海方案是该岸段的适宜围填规模。对围填海适宜规模的研究手段和方法进行了探索和尝试。提出的研究方法及推荐的如东岸段近岸浅滩适宜围填规模可为江苏滩涂资源的开发提供参考。     

基于海上实测的秋刀鱼舷提网沉降和提升性能研究

根据2015年7-10月和2016年6-10月蓬莱京鲁渔业有限公司"鲁蓬远渔019"在西北太平洋进行的海上秋刀鱼舷提网网具性能测试所获得的数据,采用线性回归方法,分析了舷提网在沉降和提升阶段,网衣的沉降深度和提升深度以及网具沉降速度和提升速度的变化状况。利用广义加性模型(GAM)探讨秋刀鱼舷提网沉降深度和提升速度各自有效的影响因子,且分析了这些影响因子与舷提网主要性能参数两者之间的关系。结果发现:(1)网衣沉降深度随时间连续增加;网具下纲和侧纲的沉降速度都是先逐渐增大,然后缓慢减小,直至沉降过程结束;网衣沉降速度波动剧烈,无规律性变化。(2)网具下纲、侧纲的提升速度均快速达到最大值然后随时间连续降低,下纲的最大提升速度大于侧纲,网衣提升速度无规律性变化,上下波动剧烈。(3)GAM模型结果显示,30 m水层流速、60 m水层流速、下纲纲索松放长度3个因子对网衣最大沉降深度有显著性影响(P0.05),影响程度依次为30 m水层的流速下纲纲索松放长度60 m水层流速。30 m水层流速和绞网速度两个因子对平均提升速度有着显著性影响(P0.05),其中,绞网速度影响最大。     

基于地基微波辐射计观测的东营地区低能见度天气指示性分析

针对东营市2016—2017年出现的27个低能见度天气过程,利用MP-3000A型地基微波辐射计二级数据,计算过程影响期间逐10 min的逆温层温差、逆温层厚度和低层相对湿度等物理量。结合空气质量和能见度变化情况,按照雾和霾、雾、降水三类天气对27次过程进行分类研究,总结地基微波辐射计观测的温湿度量对低能见度天气的指示意义和参考指标。结果表明：(1)雾和霾共同影响导致的低能见度天气出现在冬半年,PM_2.5浓度越大通常对应的能见度越低;逆温层温差和逆温层厚度与能见度的相关系数分别为-0.39和-0.45,逆温层温差增大指示能见度降低,逆温层厚度减小指示能见度升高。低层相对湿度在90%以上时,能见度受雾影响通常小于2 km;低层相对湿度在80%以下时,能见度受霾影响仍然维持在5 km以下。(2)雾影响导致的低能见度天气多出现在冬半年,与PM_2.5浓度无关;逆温层温差和逆温层厚度与能见度的相关系数分别为-0.54和-0.45。在逆温层生成和破坏阶段,逆温层温差变化幅度大,对能见度的指示性更强,而逆温层厚度变化幅度相对较小,多维持在300～400 m...     

An experimental model application of wavescreen: Dynamic pressure, water particle velocity, and wave measurements

This paper analyses the results of an application of a piled wavescreen. Experimental measurements were undertaken in the laboratory conditions for a given structural configuration under the attack of regular and irregular waves. Dynamic pressure distribution along and around the inclined piles was obtained employing pressure transducers. Using these data, in-line dynamic wave forces acting on piles were also determined. Water particle (orbital) velocities were measured at seaward and landward of the wavescreen using two acoustic Doppler velocimeters (ADV) simultaneously. Furthermore, wave data were collected using resistance type wave gauges at the seaward and landward of the structure. Based on those data, wave attenuation performance of the wavescreen was explored for two different depth values. Findings showed that piled wavescreen can provide effective shore protection as an environmentally friendly coastal structure.     

基于能量法的大直径超长钢管桩溜桩问题分析

海洋桩平台采用大直径超长桩,由于桩、锤的重量很大,沉桩过程中经常发生溜桩现象。因此为了便于打桩控制,判断溜桩的范围是非常必要的。结合实际工程对溜桩的过程和发生机理进行了探讨;利用PCPT原位测量资料,基于能量法建立了判断溜桩范围的分析计算方法。针对南海油田典型的平台桩沉桩过程中的溜桩问题进行了分析计算,验证了所提出的方法的合理性,可供桩设计以及沉桩施工参考。     

An intercomparison of GEOSAT, TOPEX and ERS1 measurements of wind speed and wave height

Mean monthly values of altimeter wind speed and wave height are compared with data from NDBC buoys. As a result of these comparisons, corrections are made to the raw data products available from these satellites. Data from the GEOSAT, TOPEX and ERS1 missions corrected in this fashion are used to show that there have been no measurable changes in the global wind and wave climate during the 10 years spanned by these various missions. It is proposed that the corrected values of wind speed and wave height provide the basis for the formation of a long-term global data base which spans the periods of these multiple missions.     

考虑软土蠕变对强度影响的高桩码头岸坡时变可靠度分析

考虑软土蠕变导致的土体抗剪强度的衰减效应,建立了软土长期强度模型,用以量化由于土体蠕变导致的土体抗剪强度参数随时间的变化规律。将时变可靠度理论结合有限元强度折减法,提出了考虑软土蠕变对强度影响的高桩码头岸坡时变可靠度算法。采用拉丁超立方抽样方法来改进传统蒙特卡罗法的随机抽样过程,提高计算效率。针对某一岸坡实例,将采用本文算法计算得到的可靠度结果与其他算法评估的结果进行对比分析,验证本文算法的可靠性。最后以我国沿海某高桩码头岸坡为例,基于本文算法评估了该码头岸坡的时变可靠度,分析了岸坡稳定性的时变规律。文中提出的时变可靠度分析方法不仅可以为在役高桩码头岸坡的安全评估提供强有力的技术支撑,同时也能为一些新建工程项目提供一定的参考应用价值。