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661.
对海滩冲流带内的流与泥沙输运的计算机模拟表明,一个将局部流加速与沿岸水面梯度结合的模型足以形成均匀间距的滩角。模拟的滩角特征以及其形成的条件与观测的自然滩角状况吻合良好。模型中的自组织机制与一个巳被接受的孤立波模型不同,在孤立波模型中沿岸孤立波产生规则的淤积模式从而形成滩角。由于这两个模型给出类似的预测,目前所具有的观测数据不足以将它们分开。 相似文献
662.
XIONG Fahui YANG Jingsui ROBINSON Paul T. XU Xiangzhen BA Dengzhu LI Yuan ZHANG Zhongming RONG He 《《地质学报》英文版》2016,90(2):425-439
Various combinations of diamond, moissanite, zircon, quartz, corundum, rutile, titanite, almandine garnet, kyanite, and andalusite have been recovered from the Dangqiong peridotites. More than 80 grains of diamond have been recovered, most of which are pale yellow to reddish-orange to colorless. The grains are all 100-200 μm in size and mostly anhedral, but with a range of morphologies including elongated, octahedral and subhedral varieties. Their identification was confirmed by a characteristic shift in the Raman spectra between 1325 cm~(-1) and 1333 cm~(-1), mostly at 1331.51 cm~(-1) or 1326.96 cm~(-1). Integration of the mineralogical, petrological and geochemical data for the Dongqiong peridotites suggests a multi-stage formation for this body and similar ophiolites in the Yarlung-Zangbo suture zone. Chromian spinel grains and perhaps small bodies of chromitite crystallized at various depths in the upper mantle, and encapsulated the UHP, highly reduced and crustal minerals. Some oceanic crustal slabs containing the chromian spinel and their inclusion were later trapped in suprasubduction zones(SSZ), where they were modified by island arc tholeiitic and boninitic magmas, thus changing the chromian spinel compositions and depositing chromitite ores in melt channels. 相似文献
663.
XIONG Fahui YANG Jingsui Paul T. ROBINSON Yildirim DILEK Ibrahim MILUSHI 《《地质学报》英文版》2016,90(Z1):245-245
正The ultramafic massif of Bulqiza,which belongs to the eastern ophiolitic belt of Albania,is the most important area for metallurgical chromitite ores.The massif consists of a thick(4 km)rock sequence,with a generalized 相似文献
664.
An analytical solution is undertaken to describe the wave-induced flow field and the surge motion of a permeable platform structure with fuzzy controllers in an oceanic environment. In the design procedure of the controller, a parallel distributed compensation (PDC) scheme is utilized to construct a global fuzzy logic controller by blending all local state feedback controllers. A stability analysis is carried out for a real structure system by using Lyapunov method. The corresponding boundary value problems are then incorporated into scattering and radiation problems. They are analytically solved, based on separation of variables, to obtain series solutions in terms of the harmonic incident wave motion and surge motion. The dependence of the wave-induced flow field and its resonant frequency on wave characteristics and structure properties including platform width, thickness and mass has been thus drawn with a parametric approach. From which mathematical models are applied for the wave-induced displacement of the surge motion. A nonlinearly inverted pendulum system is employed to demonstrate that the controller tuned by swarm intelligence method can not only stabilize the nonlinear system, but has the robustness against external disturbance. 相似文献
665.
近年以来政府增加飞机测候所,每日探测高空情形,尤注意于一九二五年春季发生于平原各省而致灾害之麈暴(Duststorm)。有时麈沙非常浓厚,飞行只能停止,但大多数仍可飞行,而沙麈之高度亦经测定。在最强烈之麈暴中,曾测得其高度,约达一万四千英尺,在其他数次之实例,其上部之界限皆不及一万八千英尺。在 O(?)lahomo 相似文献
667.
Design of bridges against large tectonic deformation 总被引:1,自引:1,他引:0
The engineering community has devoted much effort to understanding the response of soil-structure systems to seismic ground motions, but little attention to the effects of an outcropping fault offset. The 1999 earthquakes of Turkey and Taiwan, offering a variety of case histories of structural damage due to faulting, have (re)fueled the interest on the subject. This paper presents a methodology for design of bridges against tectonic deformation. The problem is decoupled in two analysis steps: the first (at the local level) deals with the response of a single pier and its foundation to fault rupture propagating through the soil, and the superstructure is modeled in a simplified manner; and the second (at the global level) investigates detailed models of the superstructure subjected to the support (differential) displacements of Step 1. A parametric study investigates typical models of viaduct and overpass bridges, founded on piles or caissons. Fixed-head piled foundations are shown to be rather vulnerable to faulting-dnduced deformation. End-bearing piles in particular are unable to survive bedrock offsets exceeding 10 cm. Floating piles perform better, and if combined with hinged pile-to-cap connections, they could survive much larger offsets. Soil resilience is beneficial in reducing pile distress. Caisson foundations are almost invariably successful. Statically-indeterminate superstructures are quite vulnerable, while statically-determinate are insensitive (allowing differential displacements and rotations without suffering any distress). For large-span cantilever-construction bridges, where a statically determinate system is hardly an option, inserting resilient seismic isolation bearings is advantageous as long as ample seating can prevent the deck from falling off the supports. An actual application of the developed method is presented for a major bridge, demonstrating the feasibility of design against tectonic deformation. 相似文献
668.
在富甲烷和含天然气水合物的海洋沉积物中,硫酸盐-甲烷界面(SMI)正逐步为大家所认识,被看作一个基本的生物地球化学氧化还原作用边界。SMI之上沉积物富硫酸盐,其下贫硫酸盐和富甲烷。SMI是一个很薄的带,甲烷的厌氧氧化作用是通过甲烷氧化作用完成的。在甲烷氧化作用过程中,甲烷和硫酸盐被消耗,形成溶解无机碳(DIC)和硫化氢(HS^-),反应式如下: 相似文献
669.
Kömle NI Hütter ES Macher W Kaufmann E Kargl G Knollenberg J Grott M Spohn T Wawrzaszek R Banaszkiewicz M Seweryn K Hagermann A 《Planetary and Space Science》2011,59(8):639-660
The thermo-mechanical properties of planetary surface and subsurface layers control to a high extent in which way a body interacts with its environment, in particular how it responds to solar irradiation and how it interacts with a potentially existing atmosphere. Furthermore, if the natural temperature profile over a certain depth can be measured in situ, this gives important information about the heat flux from the interior and thus about the thermal evolution of the body. Therefore, in most of the recent and planned planetary lander missions experiment packages for determining thermo-mechanical properties are part of the payload. Examples are the experiment MUPUS on Rosetta's comet lander Philae, the TECP instrument aboard NASA's Mars polar lander Phoenix, and the mole-type instrument HP3 currently developed for use on upcoming lunar and Mars missions. In this review we describe several methods applied for measuring thermal conductivity and heat flux and discuss the particular difficulties faced when these properties have to be measured in a low pressure and low temperature environment. We point out the abilities and disadvantages of the different instruments and outline the evaluation procedures necessary to extract reliable thermal conductivity and heat flux data from in situ measurements. 相似文献
670.
Please?refer?to?the?attachment(s)?for?more?details. 相似文献