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81.
A new contour-based watershed partitioning method, relying on tracking flow lines moving from upslope to downslope, is presented. The model works by using only contour data and consists of three principal steps: 1) Ideal Drainage Network tracking; 2) hillslope and channel elements building; and 3) actual contour-based element network construction. It automatically detects and manages sinks, peaks and saddles and calculates element attributes taking into account the non-planar shape of the elements. Watershed, subwatershed and draining area at any point can be automatically detected by using network elements interconnectivity. It is also possible to determine the Actual Drainage Network. 相似文献
82.
强调了统计域的正确选择对区域地球化学数据分析的重要性。本文以南岭研究区的W元素原始异常作为统计域,分析得出了研究区内不同成矿类型钨矿一种量化的简单元素组合特征。以此量化的元素组合特征,并结合相似度分析方法,统计了研究区内样点与各典型钨矿元素组合特征的相似性系数,其成图结果非常准确地圈定了已知的各类型钨矿,相比W元素原始异常其准确率得到了明显提升。该方法亦可认为是对地球化学场的一种成因分解,能够准确提取其中与成矿有关的异常信息。该研究可作为区域异常结构模式研究的重要补充,也可以为扩大南岭地区钨矿找矿远景提供线索。 相似文献
83.
Abstract: The structure and orientation of the posterior extremity (tail club) of the caudal vertebrae of Mamenchisaurus hochuanensis Young and Chao, 1972 from the Upper Jurassic Shangshaximiao Formation has been analyzed to determine the tail club function using Finite Element Analysis. Of the four caudal vertebrae composing the tail club, the second largest (C\"1\") was probably the most proximal, and is fixed with the preceding sequence of the caudal vertebrae, whereas the smallest (C\"4\") is free and forms the termination of the tail club. Our analysis also suggests that the tail club is more efficient in lateral swinging rather than up-and-down motion, and that the best region for the tail club to impact is at the spine of the largest of the four caudals (C\"2\"), with a maximum load for impact at about 450 N. The tail club of Mamenchisaurus hochuanensis probably also had limitations as a defense weapon and was more possibly a sensory organ to improve nerve conduction velocity to enhance the capacity for sensory perception of its surroundings. 相似文献
84.
??????????????????????????????????????????????????μ?????????;????????????????ī????????????????????????????????????????????塢?????????????????????????????????????????????о?????????????,???????????????????????????????????????????,?????????????????????? 相似文献
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87.
The Direct Matrix Method Interaction Theory (IT) proposed by Kagemoto and Yue [1] speeds up the computation of hydrodynamic coefficients for large arrays of bodies when compared to direct calculations using standard Boundary Element Method (BEM) solvers. One of the most computationally expensive parts of the matrix method is the calculation of two hydrodynamic operators, known as Diffraction Transfer Matrix (DTM) and Radiation Characteristics (RC), which describe the way an isolated geometry scatters and radiates waves, respectively. A third operator, called Force Transfer Matrix (FTM), was introduced by McNatt et al. [2] to facilitate the calculation of the forces exerted on the bodies. In this paper, a novel set of relations between the FTM and RC components is obtained using the Kochin functions specific to the cylindrical basis solutions. They extend the classical Haskind's relations, valid with incident plane waves, to the cylindrical components of the scattered and radiated fields. Moreover, an alternative demonstration of the identities is given, which does not rely on the far-field asymptotic representation of the potential. Additional expressions are provided that relate the hydrodynamic coefficients and the RC for isolated bodies as well as for arrays, and numerical checking of the derived mathematical expressions is presented. These new relations can be used to speed up calculation of the hydrodynamic operators required for the use of the IT and to test its accuracy. 相似文献
88.
铀成矿信息提取和识别是当前铀矿地质找矿工作的研究热点之一.本文利用地面伽玛能谱钾测量数据,采用差量法对铀成矿信息进行提取,结果显示,黄梅尖地区钾差量正值域与负值域呈不均匀面状展布,且具有跨越不同侵入期次岩石单元现象,钾差量亏损场与铀矿床(点)的空间位置显示较好的对应关系,反映了铀成矿作用与钾差量亏损场具有成因联系.结合野外地质调查、显微岩石学和元素地球化学对比研究表明,钾差量亏损场的形成是成矿流体与围岩作用导致水云母、钠长石、绿泥石交代钾长石的结果,是一个铀元素富集、钾质含量流失的过程;依据钾差量亏损场可大致圈定与铀成矿密切相关的"褪色"蚀变作用的空间分布范围,进一步突显了岩体内带铀矿找矿的有利信息,缩小了找矿靶区;初步划分白虎山地段和黄龙桥-4340矿点一带两处铀成矿有利地段,对下一步岩体内带铀矿找矿工作具有重要的指示作用. 相似文献
89.
This paper is concerned with the vibration isolation efficiency analysis of total or partially buried thin walled wave barriers in poroelastic soils. A two-dimensional time harmonic model that treats soils and structures in a direct way by combining appropriately the conventional Boundary Element Method (BEM), the Dual BEM (DBEM) and the Finite Element Method (FEM) is developed to this aim. The wave barriers are impinged by Rayleigh waves obtained from Biot’s poroelasticity equations assuming a permeable free-surface. The suitability of the proposed model is justified by comparison with available previous results. The vibration isolation efficiency of three kinds of wave barriers (open trench, simple wall, open trench-wall) in poroelastic soils is studied by varying their geometry, the soil properties and the frequency. It is found that the efficiency of these wave barriers behaves similarly to these in elastic soils, except for high porosities and small dissipation coefficients. The efficiency of open trench-wall barriers can be evaluated neglecting their walls if they are typical sheet piles. This does not happen with walls of bigger cross-sections, leading in general to efficiency losses. Likewise, increasing the burial depth to trench depth ratio has a negative impact on the efficiency. 相似文献
90.
Linear in-plane soil–structure interaction in two dimensions (2D) is studied in fluid-saturated, poroelastic, layered half-space using the Indirect Boundary Element Method (IBEM). The structure is a shear wall supported by a rigid embedded foundation. Exact stiffness matrices for the soil layer and half-space, and Green׳s functions of uniformly distributed loads and pore pressure on an inclined line are derived. Results of the system response in the frequency domain are presented for the special case of single soil layer over bedrock, semi-circular foundation and zero seepage force. The effects of water saturation, soil porosity, depth of soil layer, rigidity contrast between layer and bedrock are investigated in the frequency domain for incident plane P- and SV waves. The results suggest that water saturation may cause increase of the system frequency by more than 10%. 相似文献
