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61.
为了研究上海地区土层锚杆的群锚效应,本文以明德林(Mindlin)解为基础,通过引用根据试验所得的锚杆非线性传递函数,对软地层中斜拉锚杆的长度、间距、入土深度、压浆等因素对群锚效应的影响进行了探讨,得出一些有价值的结果。 相似文献
62.
皖南—浙西下古生界碳沥青成因及南方海相“有效烃源岩”问题探讨 总被引:2,自引:0,他引:2
赋存于皖南—浙西的固体碳沥青分为古油藏裂解碳沥青和古油藏破坏次生充填碳沥青两种类型 ,阐明了两类碳沥青的不同成因机制。重新认定了浙西“康山沥青脉”为碳沥青而不是泥岩。论证了皖南、浙西碳沥青的烃源为下寒武统、中—上奥陶统至下志留统、中—上寒武统等。认为加里东运动—广西事件期间是下扬子盆地相区以下寒武统黑页岩为烃源的油藏形成和部分破坏的主要时期。针对南方的油气勘探 ,提出了只有在晚期成藏中作出贡献的源岩才是“有效烃源岩”的新概念。 相似文献
63.
Seasonal Variations of the East Asian Subtropical Westerly Jet and the Thermal Mechanism 总被引:3,自引:0,他引:3
The seasonal variations of the intensity and location of the East Asian subtropical westerly jet (EAWJ) and the thermal mechanism are analyzed by using NCEP/NCAR monthly reanalysis data from 1961 to 2000. It is found that the seasonal variation of the EAWJ center not only has significant meridional migration, but also shows the rapid zonal displacements during June-July. Moreover, there exists zonal inconsistency in the northward shift process of the EAWJ axis. Analysis on the thermal mechanism of the EAWJ seasonal variations indicates that the annual cycle of the EAWJ seasonal variation matches very well with the structure of the meridional difference of air temperature, suggesting that the EAWJ seasonal variation is closely related to the inhomogeneous heating due to the solar radiation and the land-sea thermal contrast. Through investigating the relation between the EAWJ and the heat transport, it is revealed that the EAWJ weakens and shifts northward during the warming period from wintertime to summertime, whereas the EAWJ intensifies and shifts southward during the cooling period from summertime to wintertime. The meridional difference of the horizontal heat advection transport is the main factor determining the meridional temperature difference. The meridional shift of the EAWJ follows the location of the maximum meridional gradient of the horizontal heat advection transport. During the period from April to October, the diabatic heating plays the leading role in the zonal displacement of the EAWJ center. The diabatic heating of the Tibetan Plateau to the mid-upper troposphere leads to the rapid zonal displacement of the EAWJ center during June-July. 相似文献
64.
JIN Long KUANG Xueyuan HUANG Haihong QIN Zhinian WANG Yehong 《Acta Meteorologica Sinica》2005,19(2):216-225
Because of overfitting and the improvement of generalization capability (GC) available in the construction of forecasting models using artificial neural network (ANN), a new method is proposed for model establishment by means of making a low-dimension ANN learning matrix through principal component analysis (PCA). The results show that the PCA is able to construct an ANN model without the need of finding an optimal structure with the appropriate number of hidden-layer nodes, thus avoids overfitting by condensing forecasting information, reducing dimension and removing noise, and GC is greatly raised compared to the traditional ANN and stepwise regression techniques for model establishment. 相似文献
65.
CHENG Yuqi LIU Dunyi I.S. WILLIAMS JIAN Ping ZHUANG Yuxun GAO Tianshan Institute of Geology Chinese Academy of Geological Sciences Barwanzhuang Rd. Beijing China Research School of Earth Sciences Australian National University G.P.O Box Canberr A.C.T. Australia Anhui Geological Survey Changjiangdong Rd. Hefei Anhui China 《《地质学报》英文版》2000,74(4):748-765
The paper reports SHRIMP U-Pb zircon data of a dark eclogite and a post-eclogite garnet-bearing gneissic granitic rock from the Bixiling area, Yuexi County, Anhui Province, in the eastern Dabie Mountains. The eclogite, which is metamorphosed basic tuff, contains very scarce zircons in omphacite or garnet, but more zircons in quartz. They usually exhibit a double-layered texture, as shown clearly in cathodoluminescence images. Their inner main parts give a 206Pb/238U age of 757±7 Ma, representing the approximate age of the high-pressure (HP)- ultrahigh-pressure (UHP) metamorphic event during which the eclogite was formed. The outer peripheral parts of the zircons, which have been modified by late-stage fluids, give an age of 223±3 Ma. The granitic rock contains more zircons of anatectic origin found mostly in feldspar and quartz and usually also showing a similar composite texture. The inner main parts of the anatectic zircons with oscillatory zoning give a 206Pb/238U age of 727±15 Ma for the approxim 相似文献
66.
Cobalt Deposits in the Central China Orogenic Belt 总被引:2,自引:0,他引:2
XU Yong Bureau of Geology Exploration B Fuxing Rd. Beijing and ZHU Xinyou Beijing Institute of Geology for Mineral Resources Anwai Beiyuan Beijing 《《地质学报》英文版》2000,74(3):540-543
Cobalt mostly occurs as an associated metal in Cu-Ni sulphide deposits, skarn Fe-Cu-Pb-Zn deposits and volcanic-hosted massive sulphide (VHMS) or sedex deposits. There are different types of cobalt deposits in the Central China orogenic belt. In the Tamu-Kalangu Mississippi-valley type Pb-Zn deposits, many cobalt-nickel sulphide minerals were found. The cobalt content of the ore is 0.064%-0.46% in sedex-type Kendekeke Fe-Pb-Zn-Au deposits, and cobalt sulphide veins with Co contents of 4%-9% have also been found. About 28000 tons of cobalt reserves were delineated in the Dur'ngoi Cu-Co-Zn deposit of VHMS type in the A'nyemaqen Mountains. It is considered that the exploration potential for cobalt is attractive in this district, especially in sedex-type deposits and Co-rich sulphide veins in sedex-type Fe, Cu and Pb-Zn deposits and their surroundings. 相似文献
67.
YUAN Zhongxin BAI Ge Institute of Mineral Deposits Chinese Academy of Geological Sciences Baiwanzhuang Rd. Beijing ZHANG Zongqing Institute of Geology Chinese Academy of Geological Sciences Baiwanzhuang Rd. Beijing 《《地质学报》英文版》2000,74(2):148-153
Trachytic rock and its altered rock-fenite-in the Bayan Obo ore district, Inner Mongolia, China, were referred to as slate or feldspar rock before, and identified by the authors for the first time (in 1992). In the paper the mineral assemblages, structures and textures and petrochemical compositions of the rocks, as well as the electron microprobe analysis of feldspars in the rocks are described. The Sm-Nd isochron age of the trachytic rock is 1096±56 Ma, with INd=0.51100+4 (2σ) and εNd(t)= -4.4±0.7. Alterations of the trachytic rock, including microclinization, riebeckitization, aegirinization and biotitization, and accompanied rare element and REE mineralizations are discussed. Based on the occurrence of the trachytic rock and associated fenitization it is deduced that the Bayan Obo Fe-Nb-REE ore deposit is genetically related to magmatic-hydrothermal activity of an alkali carbonatite complex. 相似文献
68.
LONG Shengxiang WANG ChuanResearch Institute of Petroleum Geology China National StarPetroleum Corporation CNSPC Xueyuan R Beijing LI Yuzhan Exploration Department CNSPC Xueyuan R Beijing 《《地质学报》英文版》2000,74(3):666-673
The gas resources assessment expert system is one of the advanced methods for appraising oil and gas resources. The establishment of a knowledge base is the focal task in developing the expert system. This paper presents a summary of the mechanism and the major controlling factors in the formation of gas pools in the southeast uplift of the Songliao basin. Then an appropriate assessment model is established for trapping the gas resources and a knowledge base built in the expert system to realize the model. By using the expert system to appraise the gas-bearing probability of 25 major traps of the Quantou and Denglouku Formations in the Shiwu-Dehui area, the authors have proved that the expert system is suitable for appraising traps in the Songliao basin and similar basins. 相似文献
69.
基于近现代地图与相关地理信息,结合历史文献与实地考察,通过GIS空间分析、核密度估算、欧氏距离、基尼系数等方法,以传统林盘聚落的核心区成都郫县为例,定量揭示了1947、1970、1985、2000与2018年郫县林盘居民点的空间分布特征与场镇分布关系的变化情况。结果表明:1)不同时期林盘居民点的分布具有明显的空间差异性,在改革开放前,林盘居民点的分布极易受到政治经济中心的影响,在改革开放后,其具有均质化快速发展的特点,但城镇化的快速推进从根本上改变了林盘居民点的散居特征,其聚集程度明显增高。林盘居民点高密度区始终具有围绕传统场镇及城镇建成区分布的特点。2)传统场镇的市场半径大致为3 km,交通条件是其选址的首要因素,民国时期场镇选址主要受水路交通影响,建国后水路交通为场镇带来的交通便利逐渐被陆路交通所取代。3)传统场镇的分布会随着林盘居民的自组织行为与相关政策的调控而不断趋于均衡状态,但在改革开放之后,场镇由乡村市场驱动的自由放任式发展转变为地方政府驱动下的固定场所。4)林盘居民点具有沿河流水系分布的特点;传统时期林盘居民点与主要道路之间的关联性较低,但当前其具有沿道路分布的特点。 相似文献
70.
一种基于分步式滤波的多传感器组合导航系统算法研究 总被引:2,自引:1,他引:1
提出了一种多传感器组合导航系统的分步滤波算法。当所有传感器的观测值到来时,首先对该时刻的系统状态进行预测,然后利用常规卡尔曼滤波器和各导航传感器的观测值依次对该时刻的状态向量估计值进行更新,进而得到该时刻状态向量基于全局信息的最优融合估计。最后利用GPS/SST/高度表/SINS多组合导航系统对上述算法进行验证。仿真结果表明,该算法与集中式卡尔曼滤波算法的估计精度相同,但计算量得到降低。 相似文献