内蒙古固阳地区太古宙乌拉山群构造变形分析

乌拉山群的变质－变形问题一直有不同的认识＾「１～３」。该文以固阳地区３幅１∶５万区调资料为基础,结合９０年代以来周边地区１∶５万区调成果,提出晚太古宙乌拉山群经历了两期主要的构造变形。第一期为伸展体制下近水平分层剪切形成的固态流变褶皱和高温顺层韧性剪切带,属高角闪岩相－麻粒岩相,变形时间为太古代末;第二期构造变形为地壳抬升之后的剂压体制下,中、浅层次的紧闭同斜相似褶皱－－主期褶皱和低温韧性剪切带,     

水深测量数据采集的抗干扰技术

在水深测量数据采集中,由于外部环境的影响和数据采集系统自身的限制,使得采集水深测量数据时存在多种干扰和噪声,从而降低了数据的可靠性和准确性。针对实际作业情况,文中对常见的干扰进行了分析,对抑制与削弱干扰的措施进行了一定的研究．给出了可用于水深数据采集的多种抗干扰技术。     

末次冰消期以来东海内陆架古环境演化

通过对位于浙—闽沿岸泥质带的EC2005孔岩性、粒度以及AMS14C年代分析,探讨了研究区自末次冰消期以来的古沉积环境演化,认为是湖水或海水深度、气候变化等综合影响的结果。岩芯底部60.20～41.00 m（17.3～13.1 ka BP）为湖泊三角洲沉积序列,可划分为前三角洲—三角洲前缘—三角洲平原三个沉积亚相,物质来源主要是湖盆流域物质的输入。随着海平面的逐渐上升,海水自13.1 ka BP开始侵入研究区,形成了41.00 m的海相沉积地层,可划分为前滨—近滨—浅海三个沉积亚相,与海平面变化曲线具有良好的对应。自12.3 ka BP开始,研究区受到沿岸流影响,长江物质开始影响研究区,7.3 ka BP以来主要是来自长江的悬浮体在沿岸流作用下输送沉积而形成,稳定的泥质沉积物开始形成。全球性重要气候事件如新仙女木事件、8.2 ka冷事件在东海内陆架沉积物中也得到了良好揭示。     

末次冰消期以来东海内陆架沉积物磁化率的环境意义

对末次冰消期以来东海内陆架沉积物磁化率的影响因素及其蕴含的古环境信息进行了探讨.对位于浙闽沿岸泥质沉积中心附近的EC2005孔沉积物磁化率、岩性、粒度、常量元素、矿物以及AMS<'14>C测年数据进行了综合分析,得出以下主要结论:EC2005孔沉积物磁化率的变化受多种因素的制约,不同层位的主要控制因素不同,60.20～...     

方钢管混凝土框架内隔板节点抗震性能的试验研究

本文设计了一榀三层两跨的方钢管混凝土框架模型,梁柱节点采用内隔板节点型式。采用拟静力试验方法,对方钢管混凝土框架施加低周反复水平荷载,研究了方钢管混凝土框架内隔板节点的荷载一位移曲线、节点延性、节点破坏机制和破坏特点等抗震性能。研究结果表明,方钢管混凝土框架内隔板节点的抗震性能较好。     

An Iteration Method for Computation of Flexible Fender Piles

—In the designing of the flexible fender pile,M-method is usually adopted.But M-method isusable only in the case that the value of the force(moment M and shear force Q)exerted on the pile abovethe soil is known.In practical cases,only the percussive energy of the ship can be found,while the exactvalue of the percussive force cannot be computed directly.In this paper,a method is introduced which canbe used to calculate the inner force of flexible fender piles by a computer in these cases.First,according tothe known docking dynamic energy of a ship,the absorbed energy can be found from the deformation ofthe pile and the rubber fender respectively,at the same time the value of the force acting on the fender pilesand the reaction of fenders can be calculated.Then the inner force and displacement of the fender piles canalso be calculated further by M-method.The whole computing process is realized by a computer programand the results obtained are reasonable.In this paper,the computation,the iteration method a     

Sediment-starved sand ridges on a mixed carbonate/siliciclastic inner shelf off west-central Florida

High-resolution side-scan mosaics, sediment analyses, and physical process data have revealed that the mixed carbonate/siliciclastic, inner shelf of west-central Florida supports a highly complex field of active sand ridges mantled by a hierarchy of bedforms. The sand ridges, mostly oriented obliquely to the shoreline trend, extend from 2 km to over 25 km offshore. They show many similarities to their well-known counterparts situated along the US Atlantic margin in that both increase in relief with increasing water depth, both are oriented obliquely to the coast, and both respond to modern shelf dynamics. There are significant differences in that the sand ridges on the west-central Florida shelf are smaller in all dimensions, have a relatively high carbonate content, and are separated by exposed rock surfaces. They are also shoreface-detached and are sediment-starved, thus stunting their development. Morphological details are highly distinctive and apparent in side-scan imagery due to the high acoustic contrast. The seafloor is active and not a relict system as indicated by: (1) relatively young AMS ¹⁴C dates (<1600 yr BP) from forams in the shallow subsurface (1.6 meters below seafloor), (2) apparent shifts in sharply distinctive grayscale boundaries seen in time-series side-scan mosaics, (3) maintenance of these sharp acoustic boundaries and development of small bedforms in an area of constant and extensive bioturbation, (4) sediment textural asymmetry indicative of selective transport across bedform topography, (5) morphological asymmetry of sand ridges and 2D dunes, and (6) current-meter data indicating that the critical threshold velocity for sediment transport is frequently exceeded. Although larger sand ridges are found along other portions of the west-central Florida inner shelf, these smaller sand ridges are best developed seaward of a major coastal headland, suggesting some genetic relationship. The headland may focus and accelerate the N–S reversing currents. An elevated rock terrace extending from the headland supports these ridges in a shallower water environment than the surrounding shelf, allowing them to be more easily influenced by currents and surface gravity waves. Tidal currents, storm-generated flows, and seasonally developed flows are shore-parallel and oriented obliquely to the NW–SE trending ridges, indicating that they have developed as described by the Huthnance model. Although inner shelf sand ridges have been extensively examined elsewhere, this study is the first to describe them in a low-energy, sediment-starved, dominantly mixed siliciclastic/carbonate sedimentary environment situated on a former limestone platform.     

0414号"云娜"台风路径分析

通过对0414号“云娜”台风的高空背景场及云图的分析,揭示影响台风移动路径的辛勿理因子。研究结果表明：副高、弱环境场中台风自身内力、台风的非对称结构是影响“云娜”台风移动的主要因素,西风槽对“云娜”台风的移动起着间接作用。     

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