深海海底光缆敷设施工余量控制的原理和控制软件的应用

为解决深海有中继海底光缆项目技术难题,中国海底电缆建设有限公司开发了海底光缆敷设施工控制软件,填补我国相关领域的空白。文章介绍海底光缆敷设施工余量控制的原理和控制软件的操作流程:海底光缆余量包括区域余量、底部余量和释放余量,余量控制是海底光缆敷设施工中最关键的核心技术环节,应用控制软件可极大地降低计算量和提高计算精确度,并可通过在施工中不断调整计划,从而极大地提高施工质量,具有传统人工计算不可比拟的优势。     

Response and capacity of monopod caisson foundation under eccentric lateral loads

Monopod caisson foundation is a viable alternative for supporting offshore wind turbines located at shallow water depths. This foundation system has to resist overturning moment generated due to resultant lateral load, arising from wind and water wave action, that can act at any loading height above the seabed. This paper presents results of a numerical investigation performed to determine the influence of loading height, caisson geometry and superstructure load on the ultimate lateral capacity, initial stiffness, and soil failure zone of the foundation, when installed in very dense sand. Both the ultimate and serviceable states of the caisson foundation obtained from the analyses are represented in terms of envelopes plotted between lateral load and overturning moment. Simplified expressions, which take into account the influence of caisson geometry, loading height, and soil properties, are also presented to serve as a preliminary base for design of the monopod caisson foundation.     

花海拗陷的热演化和生烃期的磷灰石裂变径迹证据

利用裂变径迹分析方法测量了取自花海拗陷的钻井磷灰石样品的裂变径迹年龄和长度。结果表明,随井深增加年龄减小,平均径迹长度亦变短。取自白垩纪地层的磷灰石样品的裂变径迹年龄都比地层年龄年轻得多,表明沉积后曾长时间处于磷灰石裂变径迹退火带中,沉积前的径迹记录已部分消失,古地温高于今地温。利用蒙特卡罗随机取样的热史模拟方法对裂变径迹数据进行了分析,结果表明白垩纪地层沉积后曾经历过超过110 ℃的加热,达到最高古地温的地质时代是早白垩世晚期—晚白垩世末,为主要生烃期。新生代以来盆地变冷,生油岩的成熟度主要受古地温控制     

南海东北部海底沉积物波的形态、粒度特征及物源、成因分析

在南海东北部广泛发育沉积物波。通过高分辨率多波束数据、地震剖面以及重力柱状样,对沉积物波的形态特征、粒度特征、物源以及形成机制进行了分析。研究表明大致以台湾浅滩南海底峡谷为界,北侧为近北东向展布,南侧为近南北向展布。对其分布规律、地貌和形态特征及重力柱状样粒度分析表明这些沉积物波为浊流成因。沉积物波的发育与新生代晚期研究区的构造活动密切相关,自距今6.5 Ma以来台湾造山运动使台湾岛强烈抬升剥蚀,这些剥蚀物为研究区提供了大量的陆源物质,而在南海东北部陆坡区大量发育的峡谷-冲沟系统为陆缘物质向下陆坡的输送提供了良好的通道。研究区西侧的东沙隆起长期处于抬升剥蚀状态,这种抬升剥蚀也为研究区沉积物波的发育提供了部分物源。随着坡度的减缓,浊流沉积物开始堆积,在台湾浅滩南海底峡谷的北侧形成了展布方向与冲沟垂直的沉积物波,而在南侧由于台湾浅滩南海底峡谷发生转向,浊流从水道中漫溢出来,沉积物堆积下来,形成了与原先水道近于垂直的近南北向的沉积物波。     

基于小波变换法定义的波群参数

通过小波变换分析的波能过程定义了两个描述波浪群性的参数,由数值模拟波浪和实测波浪资料对其与常用的波群参数进行对比分析,结果表明基于小波波能过程定义的群性参数是有效的,从而展示了小波变换用于在时频域上分析波群的能力。详细探讨了波浪记录长度对群性参数稳定性的影响,分析结果表明,波浪观测长度对于波群参数的影响较大,在考虑波浪群性的波浪模拟及分析时,建议模拟时间长度应在400~500个波以上。     

Coral assemblages and reef growth in the Commonwealth of the Northern Mariana Islands (Western Pacific Ocean)

Reef development varies considerably around the high, raised‐limestone islands of the Commonwealth of the Northern Mariana Islands (CNMI). Here we examine the modern assemblages at 30 sites for coral composition, colony density, colony size, and fidelity. We defined four reef types and hypothesize the presence of environmentally driven ecological stasis, whereby the environment continuously selects for coral species membership, defines colony sizes, and over time creates the noted reef types. Our results show that constructional spur‐and‐groove reefs supported significantly larger coral‐colony sizes and higher coral species richness compared with high‐relief interstitial framework, low‐relief incipient, and non‐constructional coral assemblages. Non‐constructional reefs supported much smaller coral colony sizes, despite similar population densities, and were consistently found in association with high wave exposure. The distinct coral assemblages found on interstitial framework and low‐relief incipient reefs were not affiliated with any wave exposure regime, but were located adjacent to large watersheds and on islands with unique geological history. These assemblages were nested within the spur‐and‐groove species pool. Overall, modern coral cover was well predicted by bathymetric slope and watershed size, while species richness was additively influenced by two proxies of pollution, suggesting the latter is better suited for establishing management targets. In contrast with previous studies that suggested modern assemblages were biologically controlled in the CNMI, we show reef assemblages and reef development are highly influenced by long‐term environmental forcing.     

A review of the climatological characteristics of landfalling Gulf hurricanes for wind, wave, and surge hazard estimation

The climatological characteristics of landfalling Gulf of Mexico hurricanes are presented, focusing on the basic parameters needed for accurately determining the structure and intensity of hurricanes for ocean response models. These include the maximum sustained wind, radius of maximum winds, the Holland-B parameter, the peripheral or far-field pressure, the surface roughness and coefficient of drag, and the central pressure for historical hurricanes in the Gulf.Despite evidence of a slight increase in the annual number of named storms over the past 50 years, presently there is no statistically significant trend in tropical storms, hurricanes, or major hurricanes in the Gulf of Mexico. In addition, the long-term variability of tropical cyclones in the Gulf reflects the observed variability in the Atlantic basin as a whole. Analyses of hurricane winds from multiple sources suggest the presence of a bias toward overestimating the strength of winds in the HURDAT dataset from 7% to 15%. Results presented comparing HURDAT with other sources also show an overestimation of intensity at landfall, with an estimated bias of ~10%.Finally, a review of recent studies has shown that hurricane frequencies and intensities appear to vary on a much more localized scale than previously believed. This exacerbates the sampling problem for accurate characterization of hurricane parameters for design and operational applications.     

Deterministic non-linear wave prediction using probe data

The accurate prediction of non-linear sea states represents a great challenge, with a number of applications in oceanography, marine engineering, security of people and marine transportation, etc. In this paper, we report on the development of two efficient deterministic prediction models for 2D irregular wave-fields. These models are based on the exploitation of wave elevation time series given by one or more probes and on the use of two different numerical models for the wave-fields simulation. Two effective data assimilation processes are developed to improve the wave-field estimates obtained from the study of one or several probe signals, so that we obtain proper initial conditions for the forecast. The assimilation schemes have been validated on the reconstruction of model-generated observations and accurate predictions of the corresponding synthetic wave-fields evolution have been obtained.     

小振幅海洋内波的演变、破碎和所致混合

利用基于谱方法和MPI并行运算的数值模式SpectralModel,直接数值模拟了三维小振幅海洋内波的演变、破碎和所致湍流混合,指出导致其不稳定而破碎的为PSI(parametric subharmonic instability)机制;对于内波破碎所致的湍流混合过程,分析了跨等密度面扩散系数kρ、混合效率γ、浮力通量谱、动能谱以及势能谱等统计性质:内波破碎前,kρ和γ保持低值水平,浮力通量谱值为负,且集中在低波数段;内波破碎后,kρ和γ迅速增大,最大值分别约为0.9×103m2/s和0.18,浮力通量谱值在低波数段为负值,在高波数段为正值,这是因为层化湍流中势能向小尺度运动传递和动能向小尺度运动传递相比更为有效。在内波破碎、强湍流混合阶段,势能谱存在一谱段满足kz3律,P(kz)=0.2N2kz3。此外,与二维模拟结果相比较,导致内波不稳定而破碎的均为PSI机制,kρ、浮力通量谱、势能谱变化趋势大体一致;但三维数值实验中,内波破碎时间提前,湍流衰减加快;KE谱在高波数部分下降速度相对减小,更接近于kz3。     

基于闪锌矿晶体中受激电磁耦子散射产生可调谐太赫兹波的理论研究

基于受激电磁耦子散射原理,采用已报道的利用非线性光学参量振荡方法产生可调谐太赫兹波的实验条件作为理论分析的实验模型,以GaAs,GaP, InP,ZnTe晶体为代表,计算分析了在闪锌矿晶体中参量振荡产生太赫兹波的吸收、增益特性,对输出THz波的调谐特性给出了详尽分析.分析太赫兹波高效耦合输出的腔型结构,并与掺氧化镁铌酸锂晶体组成的太赫兹波参量振荡器做对比.