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1.
基于Matlab的水准点稳定性分析 总被引：1，自引：0，他引：1
通过使用Matlab功能强大的数学软件，应用于测量工程的数据处理。具体解决变形监测中水准点是否稳定的判定问题。并通过计算实例说明其可行性和优越性。 相似文献
2.
Concentration–discharge relationships have been widely used as clues to the hydrochemical processes that control runoff chemistry. Here we examine concentration–discharge relationships for solutes produced primarily by mineral weathering in 59 geochemically diverse US catchments. We show that these catchments exhibit nearly chemostatic behaviour; their stream concentrations of weathering products such as Ca, Mg, Na, and Si typically vary by factors of only 3 to 20 while discharge varies by several orders of magnitude. Similar patterns are observed at the inter‐annual time scale. This behaviour implies that solute concentrations in stream water are not determined by simple dilution of a fixed solute flux by a variable flux of water, and that rates of solute production and/or mobilization must be nearly proportional to water fluxes, both on storm and inter‐annual timescales. We compared these catchments' concentration–discharge relationships to the predictions of several simple hydrological and geochemical models. Most of these models can be forced to approximately fit the observed concentration–discharge relationships, but often only by assuming unrealistic or internally inconsistent parameter values. We propose a new model that also fits the data and may be more robust. We suggest possible tests of the new model for future studies. The relative stability of concentration under widely varying discharge may help make aquatic environments habitable. It also implies that fluxes of weathering solutes in streams, and thus fluxes of alkalinity to the oceans, are determined primarily by water fluxes. Thus, hydrology may be a major driver of the ocean‐alkalinity feedback regulating climate change. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
3.
本文利用云南省跨断层短水准测量资料,提出且证实了一个新的观点:在地震平静期点位基本稳定的条件下,地震前不同测点间的不同变化是一种地震前兆信息。 相似文献
4.
The aim of this paper is to evaluate the accuracy, stability and efficiency of the overset grid approach coupled with the RANS (Reynolds Averaged Navier-Stokes) model via the benchmark computations of flows around a stationary smooth circular cylinder. Two dimensional numerical results are presented within a wide range of Reynolds numbers (6.31 × 104 ∼ 7.57 × 105) including the critical flow regime. All the simulations are carried out using the RANS solver pimpleFoam provided by OpenFOAM, an open source CFD (Computational Fluid Dynamics) toolkit. Firstly, a grid convergence study is performed. The results of the time-averaged drag and lift force coefficients, root-mean square value of lift force coefficient and Strouhal number (St number) are then compared with the experimental data. The velocity, vorticity fields and pressure distribution are also given. One main conclusion is that the numerical solutions in regard to a fixed cylinderare not deteriorated due to the implementation of the overset grid. Furthermore, it can be an appealing approach to facilitate simulations of Vortex Induced Vibrations (VIV), which involves grid deformation. The present study is a good start to implement the overset grid to solve VIV problems in the future. 相似文献
5.
全国基准产业集群识别及在区域经济分析中的应用——以北京市为例 总被引：3，自引：1，他引：2
全国基准产业集群反映一国产业技术经济联系的一般特征,可以作为模板应用于区域集群分析。本研究首次识别我国基准产业集群,为我国的区域集群实证研究提供集群模板。以识别的基准产业集群为模板,本研究分析了北京市制造业集群的发展现状,并以北京市电子及通信设备制造业集群为例分析了该集群的组成结构及空间布局。分析发现,北京市目前已形成三个规模较大,并具有区域专业化优势的制造业集群:电子及通信设备制造、汽车及装备制造和电子元器件制造业集群。北京市电子及通信设备制造业集群的优势环节是通信设备制造和其他通信、电子设备制造业,其配套产业环节电子元器件和其他电气机械及器材制造业仍相对较弱。在空间上,北京市电子及通信设备制造业集群主要分布在城市近郊地区,朝阳、海淀、大兴区是集群环节配套较为完善的区域。 相似文献
6.
基于Benchmark模型的抑制屈曲支撑耗能减振作用分析 总被引：2，自引：0，他引：2
抑制屈曲支撑可在拉压循环荷载作用下均达到屈服,拉压承载力基本一致,滞回曲线稳定饱满,耗能能力强。基于Benchmark模型对安装抑制屈曲支撑的钢框架结构基于ANSYS的数值分析表明,抑制屈曲支撑不仅可使结构在小震时的抗侧刚度有所提高,同时在大震时通过其往复滞回变形发挥耗能减振作用,大大地降低了结构的地震响应,提高了结构的抗震性能。同时分析表明考虑高阶振型影响的能力谱分析方法是一种更为精确的分析方法。 相似文献
7.
结构磁流变阻尼半主动控制的改进算法与仿真分析 总被引：19，自引：0，他引：19
基于线性二次型最优控制理论,结合磁流变阻尼器装置的出力特点,提出了结构磁流变阻尼半主动控制的两种改进算法：以速度负反馈渐进逼近主动最优的界限滑动半主动控制算法和基于结构响应状态组合反馈的界限开关半主动控制算法。首先给出了采用磁流变阻尼器装置控制结构振动的系统框图,然后结合一个三层Benchmark模型,仿真分析其在多种地震输入工况下,LQR、磁流变阻尼两种半自动和两种被动控制下的控制效果,最后给出了Benchmark评价指标。 相似文献
8.
通过对青海省察尔汗盐湖地区裹体碎石桩复合地基的静载试验,认为复合地基试验中堆载反力梁装置及正确布设基准梁对试验结果有较大的影响。 相似文献
9.
A new benchmark semi-analytical solution is proposed for the verification of density-driven flow codes. The problem deals with a synthetic square porous cavity subject to different salt concentrations at its vertical walls. A steady state semi-analytical solution is investigated using the Fourier–Galerkin method. Contrarily to the standard Henry problem, the cavity benchmark allows high truncation orders in the Fourier series and provides semi-analytical solutions for very small diffusion cases. The problem is also investigated numerically to validate the semi-analytical solution. The obtained results represent a set of new test case high quality data that can be effectively used for benchmarking density-driven flow codes. 相似文献
10.
Many popular groundwater modeling codes are based on the finite differences or finite volume method for orthogonal grids. In cases of complex subsurface geometries this type of grid either leads to coarse geometric representations or to extremely fine meshes. We use a coordinate transformation method (CTM) to circumvent this shortcoming. In computational fluid dynamics (CFD), this method has been applied successfully to the general Navier–Stokes equation. The method is based on tensor analysis and performs a transformation of a curvilinear into a rectangular unit grid, on which a modified formulation of the differential equations is applied. Therefore, it is not necessary to reformulate the code in total. We applied the CTM to an existing three-dimensional code (SHEMAT), a simulator for heat conduction and advection in porous media. The finite volume discretization scheme for the non-orthogonal, structured, hexahedral grid leads to a 19-point stencil and a correspondingly banded system matrix. The implementation is straightforward and it is possible to use some existing routines without modification. The accuracy of the modified code is demonstrated for single phase flow on a two-dimensional analytical solution for flow and heat transport. Additionally, a simple case of potential flow is shown for a two-dimensional grid which is increasingly deformed. The result reveals that the corresponding error increases only slightly. Finally, a thermal free-convection benchmark is discussed. The result shows, that the solution obtained with the new code is in good agreement with the ones obtained by other codes. 相似文献