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991.
Low-mature gases and their resource potentiality 总被引:1,自引:0,他引:1
In the 80’s of last century, based on the advances in natural gas exploration practice, the concepts of bio-thermocatalytic transitional-zone gas and early thermogenetic gas were proposed, and the lower limit Ro values for the formation and accumulation of thermogenetic natural gases of industrial importance have been extended to 0.3%–0.4%. In accordance with the two-stage model established on the basis of carbon isotope fractionation involved in the formation of coal-type natural gases, the upper limit Ro ... 相似文献
992.
Wei Lin Michel Faure Yonghong Shi Qingchen Wang Zhong Li 《International Journal of Earth Sciences》2009,98(6):1259-1274
The south-western Chinese Tianshan orogenic belt is famous for its omphacite-bearing blueschists and associated eclogite-facies
metavolcanic rocks. Although numerous petrologic, geochemical and geochronological studies are available, structural data
and interpretations are still rare. This paper provides new structural data, including bulk geometry of structures and kinematic
analyses, based on field and laboratory studies along the Akyazhi, Keburt and Muzaert Rivers. The study area is divided into
three tectonic units, namely (1) a Southern Unit composed of weakly metamorphosed sedimentary rocks of Silurian age; (2) a
Central HP/LT Unit composed of blueschist-eclogite-facies metamorphic rocks derived from basalts, pelites and volcaniclastic
rocks; (3) a Northern Unit, which consists of a Carboniferous magmatic arc developed upon an amphibolite-facies metamorphic
continental basement. Our structural analysis documents a polyphase deformation. The main event (D1) is reflected by Devonian to Carboniferous top-to-the northwest ductile shearing, coeval with HP/LT metamorphism. This is
followed by north-directed thrusting (D2) of the Southern Unit over the Central HP/LT Unit, coeval with retrogression of the high-pressure rocks. A top-to-the-S (SE)
deformation (D3) overprints the earliest events and is observed in the Northern and Central Units. Lastly, Permian dextral ductile-brittle
wrenching (D4) overprints the older flat-lying fabrics. D4 is conspicuous along the Nalati Fault that separates the Northern Unit from the Central HP/LT Unit. The absolute timing of
these deformation events is discussed in the light of available radiometric dating. The structural, metamorphic and geochronological
data are integrated into a geodynamic model of the south-western Chinese Tianshan that emphasizes south-directed subduction
of microcontinents located between Tarim and Junggar. 相似文献
993.
Statistical models using historical data on crop yields and weather to calibrate relatively simple regression equations have been widely and extensively applied in previous studies, and have provided a common alternative to process-based models, which require extensive input data on cultivar, management, and soil conditions. However, very few studies had been conducted to review systematically the previous statistical models for indentifying climate contributions to crop yields. This paper introduces three main statistical methods, i.e., time-series model, cross-section model and panel model, which have been used to identify such issues in the field of agrometeorology. Generally, research spatial scale could be categorized into two types using statistical models, including site scale and regional scale (e.g. global scale, national scale, provincial scale and county scale). Four issues exist in identifying response sensitivity of crop yields to climate change by statistical models. The issues include the extent of spatial and temporal scale, non-climatic trend removal, colinearity existing in climate variables and non-consideration of adaptations. Respective resolutions for the above four issues have been put forward in the section of perspective on the future of statistical models finally. 相似文献
994.
Xiaohua Tong Wenzhong Shi Dajie Liu 《International journal of geographical information science》2013,27(11):1413-1432
In this paper, a least‐squares based cadastral parcel area adjustment in geographic information systems (GIS) is developed based on (1) both the areas and coordinates being treated as observations with errors; and (2) scale parameters being introduced to take the systematic effect into account in the process of cadastral map digitization. The area condition equation for cadastral parcel considerations of scale parameters and geometric constraints is first constructed. The effects of the scale error on area adjustment results are then derived, and statistical hypothesis testing is presented to determine the significance of the scale error. Afterwards, Helmert's variance component estimation based on least‐squares adjustment using the condition equation with additional parameters is proposed to determine the weight between the coordinate and area measurements of the parcel. Practical tests are conducted to illustrate the implementation of the proposed methods. Four schemes for solving the inconsistencies between the registered areas and the digitized areas of the parcels are studied. The analysis of the results demonstrates that in the case of significant systematic errors in cadastral map digitization, the accuracies of the adjusted coordinates and areas are improved by introducing scale parameters to reduce the systematic error influence in the parcel area adjustment. Meanwhile, Helmert's variance component estimation method determines more accurate weights of the digitized coordinates and parcel areas, and the least‐squares adjustment solves the inconsistencies between the registered areas and the digitized areas of the parcels. 相似文献
995.
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???????????????????????????????????:λ????????????????????λ?????????????????????????????????;??????????????????????????????????????????????????????????????????????????????????????????????????????3????????????:???????????????????????????????????????÷??????н????????? 相似文献
996.
利用玉树震后地质调查获取的地表破裂位移,参考余震精定位结论以及地震波和InSAR反演结果,构建了玉树Ms7.1地震发震断层模型.基于弹性-粘弹分层介质模型中平面矩形位错理论,考虑介质自重的影响,模拟了玉树地震同震形变和重力变化.图像显示,玉树绝对重力点刚好位于同震重力变化极值附近,变化量达到25.02 ×10-8 m·s-2.通过对震前重力变化以及对两台FG-5绝对重力仪的一致性进行讨论,认为实测玉树台27.2 ×10-8 m·s-2为同震重力变化,这与基于位错理论的同震模拟结果一致,是对位错理论近场变化的1次很好的验证. 相似文献
997.
998.
北斗卫星系统是中国正在实施的自主研发、独立运行的卫星定位与通信系统.因其具有短报文通信功能,进行相应的软硬件开发,可以用于传输包括烈度在内的强震动台网观测数据.通过北斗卫星传输烈度速报的性能测试和在芦山7.0级大地震中的实际应用效果,对北斗卫星系统目前在强震动台网数据传输中的应用方式和效能进行介绍. 相似文献
999.
Modeling the circulation in the Gulf of Tonkin, South China Sea 总被引:4,自引:0,他引:4
The circulation in the Gulf of Tonkin (Beibu Gulf) was studied using the Princeton Ocean Model, which was forced with the daily surface and lateral boundary fluxes for 2006 and 2007, as well as tidal harmonics and monthly climatological river discharges. In the southern Gulf, the vertically averaged circulation was anti-cyclonic in summer and changed to cyclonic in winter. Although it was highly correlated with the local wind, the southern gyre was driven primarily by the South China Sea (SCS) general circulation from the south. Flows in the Qiongzhou Strait that played a significant role in determining the circulation variability in the northeastern Gulf could be eastward or westward at any given day in summer or winter, but the seasonal mean current was eastward from late spring through summer and westward during the rest of the year, with an annual mean westward transport of ~0.1 Sv into the Gulf. Different water masses were distinguished at the surface with the warm and saline SCS water in the south, relatively fresh plume waters along the northern and western coasts of the Gulf, and the mixture of the two in between. At lower levels, two cold water masses were identified in the model, and each had T/S distributions qualitatively similar to the observations obtained in 2007. These two water masses were produced throughout the winter, sheltered from the surface warming by a thermocline as the season progressed, and eventually disappeared in late fall. 相似文献
1000.
基于高灵敏度检波器数据的分频匹配滤波方法及其应用(英文) 总被引:1,自引:0,他引:1
具有较高自然频率的高灵敏度检波器在采集数据时可以通过压制低频信号来相对提高高频能量,但这也造成了其低频响应差的问题,如果将高灵敏度数据与常规数据进行优势组合,就可以达到拓宽频带的目的。为此,本文提出分频段匹配滤波的方法,即在保持常规数据低频优势的前提下,对其高频端进行匹配滤波,实现不同频带范围内的优势互补,从而改善地震记录。通过引入不同主频的雷克子波模拟得到具有常规数据和高灵敏度数据特点的理论模型,论证了分频匹配滤波方法的可行性。在对野外单炮地震记录处理中发现,分频匹配滤波方法拓宽了地震记录的有效频带宽度,提高了地震记录的分辨率。 相似文献