全球海底光缆传输网络的节点职能与鲁棒性评价     

章卓凡  张维阳  翟庆华  钱雨昕  陈硕 《世界地理研究》2022,31(5):929-940

海底光缆传输网络是全球信息传递和要素流动的重要基础设施支撑,国家或地区在全球海底光缆网络中的节点职能和对网络鲁棒性的影响事关国家信息通信安全。在此背景下,研究基于全球网络基础设施Infrapedia数据库,提取了1991—2017年近30年全球光缆分布数据,运用复杂网络分析方法,研究了不同国家或地区在全球光缆网络中承担“传输职能”和“枢纽职能”的特征及其演变,并探究了全球海底光缆网络的鲁棒性。研究发现：①国家或地区的信息传输职能和枢纽职能具有不同的模式;其中信息传输职能较为扁平化,且呈明显廊道格局,咽喉海峡沿线的国家或地区占据重要位置;信息枢纽职能具有明显的等级结构。②毗邻海峡的地缘战略位置、背靠强劲的国家实力、增长迅速的市场需求等共同塑造了全球海底光缆网络中的重要节点。③部分节点（尤其是高中间中心性的节点）发生故障会导致整个网络功能的大幅下降。研究从避免海底光缆链接的单一性、提升全球枢纽职能等方面提出了维护我国海底信息传输安全的启示。  相似文献   

基于VOF方法的海底管道溢油扩散数值模拟研究     

李志刚  蒋梅荣  余建星 《海洋工程》2016,34(6):100-110

在海底输油管道运行过程中,管道渗漏、穿孔及破碎都会导致原油泄漏。对溢油运动的轨迹及其扩散范围作出预报可为溢油事故的处理提供及时、准确的信息,指导应急处理的正确实施。基于工程实际需求,采用有限体积法,结合k-ε紊流模型,建立了海流作用下海底输油管道溢油扩散数值模型。采用VOF方法(volume of fluid method)追踪多相流界面。首先,将数值模拟结果与Fan的实验值及Zheng和Yapa的数值结果进行了对比,验证数值模型的可靠性;其次,研究了不同原油溢出速度与环境水深对不同时刻溢油轨迹、到达海面时间、横向漂移距离与海面扩散范围的影响。研究表明:随原油溢出速度增大,溢油到达海面时间逐渐减小,溢油横向漂移距离与海面扩散范围则逐渐增大;随环境水深增大,溢油到达海面时间逐渐增大,且其变化接近线性分布。  相似文献   

Shallow‐water microbialite‐volcaniclastic facies association in the Cambro‐Ordovician Mt Windsor Subprovince,Australia     

M. G. Doyle  J. McPhie 《Australian Journal of Earth Sciences》2013,60(6):815-831

The Trooper Creek Formation is a mineralised submarine volcano‐sedimentary sequence in the Cambro‐Ordovician Seventy Mile Range Group, Queensland. Most of the Trooper Creek Formation accumulated in a below‐storm‐wave‐base setting. However, microbialites and fossiliferous quartz‐hematite ± magnetite lenses provide evidence for local shoaling to above fairweather wave‐base (typically 5–15 m). The microbialites comprise biogenic (oncolites, stromatolites) and volcanogenic (pumice, shards, crystal fragments) components. Microstructural elements of the bioherms and biostromes include upwardly branching stromatolites, which suggest that photosynthetic microorganisms were important in constructing the microbialites. Because the microbialites are restricted to a thin stratigraphic interval in the Trooper Creek area, shallow‐water environments are interpreted to have been spatially and temporarily restricted. The circumstances that led to local shoaling are recorded by the enclosing volcanic and sedimentary lithofacies. The microbialites are hosted by felsic syneruptive pumiceous turbidites and water‐settled fall deposits generated by explosive eruptions. The microbialite host rocks overlie a thick association (≤?300 m) of andesitic lithofacies that includes four main facies: coherent andesite and associated autoclastic breccia and peperite; graded andesitic scoria breccia (scoriaceous sediment gravity‐flow deposits); fluidal clast‐rich andesitic breccia (water‐settled fall and sediment gravity‐flow deposits); and cross‐stratified andesitic sandstone and breccia (traction‐current deposits). The latter three facies consist of poorly vesicular blocky fragments, scoriaceous clasts (10–90%), and up to 10% fluidally shaped clasts. The fluidal clasts are interpreted as volcanic bombs. Clast shapes and textures in the andesitic volcaniclastic facies association imply that fragmentation occurred through a combination of fire fountaining and Strombolian activity, and a large proportion of the pyroclasts disintegrated due to quenching and impacts. Rapid syneruptive, near‐vent aggradation of bombs, scoria, and quench‐fragmented clasts probably led to temporary shoaling, so that subsequent felsic volcaniclastic facies and microbialites were deposited in shallow water. When subsidence outpaced aggradation, the depositional setting at Trooper Creek returned to being relatively deep marine.  相似文献   

辽宁陆东凹陷前河油田水下扇沉积粒度特征及水流强度分析          下载免费PDF全文

雷霄雨 《沉积与特提斯地质》2015,35(3):63-67

前河油田九佛堂组为一套水下扇沉积。通过对不同层位取心井粒度资料分析及对比,分析其差异的原因,确定各层位搬运方式及沉积作用形式,并运用霍姆斯水流强度图分析从湖盆边缘向湖盆内的水流强度变化。根据岩性组合及测井曲线特征,识别出扇根、扇中前缘及扇端3种微相。并认为沿水流及砂体发育方向为部署有利区带。  相似文献   

A Tsunami Generated by a Possible Submarine Slide: Evidence for Slope Failure Triggered by the North Anatolian Fault Movement     

K.?MinouraEmail author  F.?Imamura  U.?Kuran  T.?Nakamura  G. A.?Papadopoulos  D.?Sugawara  T.?Takahashi  A. C.?Yalciner 《Natural Hazards》2005,36(3):297-306

A tsunamigenic sediment layer has been discovered in fluvio-alluvial sequences on the northern coast of the Marmara Sea, northwestern Turkey. The layer consists of unsorted silty coarse sand including terrestrial molluscs and charcoal fragments. The AMS radiometric ages of the shells have been estimated at around BC 400, AD 300, AD 400, and AD 1000. We propose that a tsunami occurred in the Marmara Sea in the middle of 11th century and invaded the fluvial plains. The older fossils were derived from the underlying horizons, and it is probable that buoyant materials such as terrestrial molluscs and charcoals were isolated from liquefied sediments during submarine sliding. Slope failure of coastal blocks triggered by fault movement generated tsunamis, which might have transported floating materials to the backshore.  相似文献   

Volcanic and Scientific Activity at Kick ’em Jenny Submarine Volcano 2001–2002: Implications for Volcanic Hazard in the Southern Grenadines,Lesser Antilles     

Jan?M.?LindsayEmail author  John?B.?Shepherd  Doug?Wilson 《Natural Hazards》2005,34(1):1-24

Kick em Jenny submarine volcano, ~8 km north of Grenada, has erupted at least 12 times since it was first discovered in 1939, making it the most frequently active volcano in the Lesser Antilles arc. The volcano lies in shallow water close to significant population centres and directly beneath a major shipping route, and as a consequence an understanding of the eruptive behaviour and potential hazards at the volcano is critical. The most recent eruption at Kick em Jenny occurred on December 4 2001, and differed significantly from past eruptions in that it was preceded by an intensive volcanic earthquake swarm. In March 2002 a multi-beam bathymetric survey of the volcano and its surroundings was carried out by the NOAA ship Ronald H Brown. This survey provided detailed three-dimensional images of the volcano, revealing the detailed morphology of the summit area. The volcano is capped by a summit crater which is breached to the northeast and which varies in diameter from 300 to 370 m. The depth to the summit (highest point on the crater rim) is 185 m and the depth to the lowest point inside the crater is 264 m. No dome is present within the crater. The crater and summit region of Kick em Jenny are located at the top of an asymmetrical cone which is about 1300 m from top to bottom on its western side. It lies within what appear to be the remnants of a much larger arcuate collapse structure. An evaluation of the morphology, bathymetry and eruptive history of the volcano indicates that the threat of eruption-generated tsunamis is considerably lower than previously thought, mainly because the volcano is no longer thought to be growing towards the surface. Of more major and immediate concern are the direct hazards associated with the volcano, such as ballistic ejecta, water disturbances and lowered water density due to degassing.  相似文献   

海洋地理信息系统中两个问题的探讨     

查正军  鲍峰  欧建良 《测绘工程》2006,15(6):4-7

由离散水深数据如何描述海底地貌以及水深数据与属性数据如何关联一直是海洋地理信息系统(MGIS)需要解决的问题。文中探讨利用超图中层次结构和非层次关系对海底山峰构建,最后在一个试验区内实现,论证了其可行性。  相似文献   

信息熵在潜艇作战系统多目标任务调度中的应用     

宋奂寰  王树宗 《武汉大学学报(信息科学版)》2012,37(12):1477-1481

为解决潜艇多目标作战的任务调度问题,针对处理器服务的作战任务队列,提出了基于目标信息增量的作战任务调度算法。运用信息处理系统计算各目标信息增量来描述作战系统对各目标状态的了解程度,并分别给出了作战系统目标探测、识别和跟踪过程中信息增量的计算方法。仿真结果表明,该方法能够定量描述作战任务调度和目标信息不确定性之间的关系,具有一定的可行性和实用性。  相似文献   

太平洋水下海山磷酸盐的成因及形成环境   总被引：3，自引：1，他引：2  

潘家华  刘淑琴  杨忆  刘学清 《地球学报》2004,25(4):453-458

笔者首次对太平洋与大洋富钴结壳密切相关的海山磷酸盐的成因及形成环境进行了比较深入的研究。研究发现 ,各种产出形态的磷酸盐都不同程度地交代碳酸盐等含钙物质 ,而呈现出交代生物结构、交代凝灰结构、交代角砾状结构及交代填间结构等各种交代结构 ,反映了磷酸盐的交代成因。此外 ,其δ13 C值 (变化于 0 .7‰～ 2 .0‰之间 )也证实其属于交代成因。磷酸盐中Na、Mg、Sr、F、P2 O5含量以及Na/P2 O5、Mg/P2 O5、Sr/P2 O5、F/P2 O5的比值 ,特别是晶格中结构CO2 的含量 (变化于 5 .7%～ 6 .2 %之间 ) ,与形成于氧化环境下的Blakeplateau、ChathamRise、AgulhasBank等处的磷酸盐相近 ,表明调查区磷酸盐亦形成于氧化环境。氧同位素测定结果表明 ,磷酸盐的形成温度为 5 .8～ 14 .8℃ ,平均为 11.5℃ ,显示其形成于正常的海水温度环境。西、中太平洋海山磷酸盐形成环境十分接近的事实暗示 ,西、中太平洋广大区域内的成磷事件存在着时间上和成因上的统一性和相似性。  相似文献   

海底斜坡土体失稳的研究进展   总被引：1，自引：0，他引：1  

胡光海  刘忠臣  孙永福  张效龙 《海岸工程》2004,23(1):63-72

根据国内外最新的文献,综述了海底斜坡失稳研究核心问题的进展情况。这些进展主要包括海底斜坡土体失稳的定性和定量研究,以及海底斜坡土体失稳后演变趋势的定性和定量研究。  相似文献