On the Variability of the Fluxes of Momentum and Sensible Heat     

William M. Drennan  Lynn K. Shay 《Boundary-Layer Meteorology》2006,119(1):81-107

Direct measurements of the air–sea turbulent fluxes of momentum and heat, along with surface currents, waves and supporting meteorological variables, were acquired during a recent field campaign. Surface currents, measured from a very high frequency radar, were found to steer the stress away from the mean wind direction. Although this effect has been reported in a recent scatterometer study, this is the first time it has been observed in an in situ study with co-located flux, wind and surface current measurements. Data collected during a week of stationary conditions are used to investigate and quantify the sampling variability of the air–sea fluxes of momentum and sensible heat.  相似文献   

The Genesis of Intermediate and Silicic Magmas in Deep Crustal Hot Zones   总被引：55，自引：2，他引：55  

ANNEN  C.; BLUNDY  J. D.; SPARKS  R. S. J. 《Journal of Petrology》2006,47(3):505-539

A model for the generation of intermediate and silicic igneousrocks is presented, based on experimental data and numericalmodelling. The model is directed at subduction-related magmatism,but has general applicability to magmas generated in other platetectonic settings, including continental rift zones. In themodel mantle-derived hydrous basalts emplaced as a successionof sills into the lower crust generate a deep crustal hot zone.Numerical modelling of the hot zone shows that melts are generatedfrom two distinct sources; partial crystallization of basaltsills to produce residual H₂O-rich melts; and partial meltingof pre-existing crustal rocks. Incubation times between theinjection of the first sill and generation of residual meltsfrom basalt crystallization are controlled by the initial geotherm,the magma input rate and the emplacement depth. After this incubationperiod, the melt fraction and composition of residual meltsare controlled by the temperature of the crust into which thebasalt is intruded. Heat and H₂O transfer from the crystallizingbasalt promote partial melting of the surrounding crust, whichcan include meta-sedimentary and meta-igneous basement rocksand earlier basalt intrusions. Mixing of residual and crustalpartial melts leads to diversity in isotope and trace elementchemistry. Hot zone melts are H₂O-rich. Consequently, they havelow viscosity and density, and can readily detach from theirsource and ascend rapidly. In the case of adiabatic ascent themagma attains a super-liquidus state, because of the relativeslopes of the adiabat and the liquidus. This leads to resorptionof any entrained crystals or country rock xenoliths. Crystallizationbegins only when the ascending magma intersects its H₂O-saturatedliquidus at shallow depths. Decompression and degassing arethe driving forces behind crystallization, which takes placeat shallow depth on timescales of decades or less. Degassingand crystallization at shallow depth lead to large increasesin viscosity and stalling of the magma to form volcano-feedingmagma chambers and shallow plutons. It is proposed that chemicaldiversity in arc magmas is largely acquired in the lower crust,whereas textural diversity is related to shallow-level crystallization. KEY WORDS: magma genesis; deep hot zone; residual melt; partial melt; adiabatic ascent  相似文献   

滑坡稳定性评价及治理工程设计软件Slope Designer     

李长冬  胡新丽 《地质科技情报》2006,25(1):95-99

主要介绍了Slope Designer 1.2的设计开发思路和主要功能.该软件是基于Windows面向对象技术开发的滑坡稳定性评价与治理工程设计的一体化工程软件,采用Visual C 进行程序设计,包括稳定性分析子模块和抗滑桩设计子模块2部分,可对地震作用、暴雨等不同工况下的滑坡进行稳定性评价和推力计算,并能够对(锚拉)抗滑桩(弹性桩、刚性桩)的弯矩、剪力及侧应力进行计算,最后根据内力计算结果完成配筋计算.在三峡库区兴山县二里半滑坡的应用研究表明,该软件具有很好的工程实用性.  相似文献   

花岗岩残积土开挖边坡的工程特性   总被引：6，自引：0，他引：6  

吴能森 《山地学报》2006,24(4):431-436

为研究开挖效应对花岗岩残积土工程特性的影响,进行压缩性和抗剪强度试验,研究应力卸荷、饱和软化、失水干缩的影响以及注浆加固效果,然后从几何微结构及其损伤角度,研究其开挖边坡滑动的微观机理,主要结果有:边坡开挖后,随着临空面的形成和暴露,失水干缩、应力卸荷及饱和软化等开挖效应将导致土体弱化,而且当它们共同作用时,弱化效应叠加;对花岗岩残积土注水泥浆,可修复并增强土体的微结构,减弱开挖效应;提出的微结构几何模型,基本反映了花岗岩残积土的微观特征,可较好地解释开挖效应,揭示开挖边坡的滑动破坏机理。研究成果可为花岗岩残积土开挖边坡防护的设计、施工及新技术研究提供概念上指导和参考。  相似文献   

应用遗传神经网络研究碎屑岩储集层流动单元     

李海燕  彭仕宓 《地质科技情报》2007,26(3):56-60

应用遗传神经网络模式识别方法,以文72块沙三中为例,在取芯关键井流动单元聚类分析的基础上,选用流动层指数、孔隙度、渗透率、粒度中值、泥质含量、最大孔喉半径6项参数,将取芯井流动单元划分为4类,采用神经网络模式识别方法,通过建立遗传神经网络的学习及预测模型,对文72块沙三中油藏进行了流动单元识别,阐述了各类流动单元的特征,并应用序贯指示模拟,获得了流动单元的时空展布.流动单元与沉积微相空间分布的对比表明,物性和储集能力都较好的流动单元大部分位于水下分支水道微相中部及河口坝微相,水道和河口坝沉积是控制物性较好流动单元的主要沉积微相.储集层流动单元比沉积微相更精细地刻画了影响储集层流体流动的地下结构,通过流动单元研究可以预测剩余油的可能分布.  相似文献   

非线性回归法求解爆破振动速度衰减公式参数   总被引：15，自引：1，他引：15  

吕涛  石永强  黄诚  李海波  夏祥  周青春  李俊如 《岩土力学》2007,28(9):1871-1878

准确分析场地爆破振动衰减规律是爆破工程设计的基本依据。通过考察爆破振动速度衰减公式中参数的线性回归方法和非线性回归方法,提出了线性残差平方和与非线性（亦即标准残差平方和）的概念,给出了求解衰减公式参数的非线性回归法,并详述了该方法的实现过程。结合工程实例,以标准残差平方和作为爆破振动实测数据与衰减公式拟合值偏差大小的判断依据,分析了线性和非线性回归分析方法得到的萨道夫斯基公式和其修正公式的标准残差平方和。分析结果表明,非线性回归分析方法的准确度明显高于线性回归分析方法;分别采用线性回归和非线性回归方法得到的萨道夫斯基公式和其修正公式的标准残差平方和非常接近,因此,采用两种形式的公式拟合爆破振动衰减规律都是可行的。  相似文献   

流变学基础模型的地质应用及启示   总被引：5，自引：1，他引：5  

刘瑞珣 《地学前缘》2007,14(4):61-65

地质作用经常是流变过程,岩石经受长时间应力作用可以在小应力条件下产生大变形。地质作用具有充分漫长的时间,所以野外露头成为研究天然流变学最好的现场,流变学理论在力学中自19世纪下半叶以来已经有迅速的发展,但用于解释地质作用的文献仍然很少。文中介绍一个基本粘弹性模型——马克斯威尔模型作为描述岩石变形的实例,同时给出应变与应力和时间三者的本构关系。代入真实岩石的“E”值和“η”值,获得了岩石的“马克斯威尔松弛时间”,约为1012s,约合3.2万年,这意味着使应力经松弛降低到某一明显程度和使应变经蠕变增加到某一明显程度在数量级上至少需要10万年以上。  相似文献   

青藏高原重力异常与地形高程的负相关校正     

张春灌  张明华  安玉林 《物探与化探》2007,31(3):236-238,

针对消除青藏高原重力异常与地形高程呈负相关关系所引起的假异常,提出了均衡校正和残余负相关校正相结合的一套具有可操作性的校正方法,并对青藏高原可可西里地区重力异常数据进行了处理,效果明显,验证了方法的有效性.  相似文献   

大民屯凹陷高分辨地震资料处理技术研究     

赵延江  段云卿  杨文军  高海燕  皮金云 《物探与化探》2007,31(4):370-373

通过对大民屯凹陷地震资料的详细分析，针对洼陷部位信噪比高、主要目的层沙三、沙四段频率相对较低的特点，研究出一套高分辨率处理技术，主要包括子波处理技术及优势频带约束下的分频处理技术，能满足沙三、沙四段储层横向预测的需要，见到了较好的应用效果。  相似文献   

Analytical modelling of wintertime coastal jets in the Adriatic Sea     

Martin Lazar  Marko Pavić  Zoran Pasarić  Mirko Orlić 《Continental Shelf Research》2007

Two diagnostic models, reproducing circulation generated in a marginal sea by variable density, have been developed. The models’ domain is a 2D transverse section for which analytical solutions have been obtained. They describe the winter situation in the northern Adriatic, with a strong vertical mixing present and the density maximum dominating the centre of the basin. Both models employ Boussinesq-type parametrisation of friction and linear slip at the bottom. The first model allows for frictional departure from hydrostatic equilibrium and includes vertical friction only. The second one is hydrostatic but allows for lateral friction as well. The results obtained by the two models are similar and to some extent dependent on the vertical and bottom friction. They reproduce several well known characteristics of the Adriatic circulation (cyclonic surface flow, downwelling in the central and larger part of the basin compensated by upwelling in the coastal zone) but also predict some phenomena that are still not well understood. A conspicuous feature of the model results are coastal jets, which were observed in the Adriatic on several occasions. The present models show that the distance of jets from the coasts depends on lateral friction: it is found to vary from 1 up to 10 km on the Italian side and between 2 and 15 km on the Croatian side. Both models reproduce the west–east asymmetry, with the wider current on the east side of the basin. The asymmetry is a subject on which conflicting empirical results exist in the Adriatic. In the two models cyclonic flow occupies the whole water column, which disagrees with some recent theoretical findings of the near-bottom anticyclonic flow and thus leaves the issue open.  相似文献