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161.
内蒙古入境旅游消费结构变化及其对国民消费的贡献 总被引:1,自引:0,他引:1
为探察内蒙古入境旅游发展水平及经济效应,依据2003—2014年内蒙古有关统计数据,用变动度、高级指数、地位指数、弹性系数和贡献率等指标,分析入境旅游消费结构变化及其对国民消费的贡献。结果表明:2003年以来,内蒙古入境游人均消费呈波动式缓慢增长;各要素项消费额及结构、逐年消费结构变动度呈波动起伏变化;基本消费和非基本消费比例在小幅波动中基本稳定,消费结构高级化指数均大于1,且呈起伏变化;入境旅游消费构成中购物比重最高,交通费比重次之,均值分别为43.6%,21.8%;入境游总消费、各项消费对三次产业及对应行业的弹性系数小于1与大于1的年份交替出现,地位指数、贡献率起伏变化,入境旅游消费对国民消费的拉动作用不稳定。 相似文献
162.
1994—2007年中国主要城市的规模产出效应实证研究:一个面板模型 总被引:1,自引:0,他引:1
建立柯布道格拉斯城市规模产出效应面板模型,对1994—2007年全国30个主要城市的规模产出效应进行了实证研究,研究表明,城市规模对产出有显著性影响,城市规模产出效应中包含显著的时间影响和地区影响。包含时间影响的变截距模型显示,城市规模产出弹性为0.128,时间影响系数由1994年的-0.652单调增加到2007年的0.615,说明城市规模产出效应、资源使用效率和城市化质量逐步提高;包含地区影响的变系数模型表明,城市规模对产出影响中存在显著的固定水平效应和增长效应,水平效应在-13.569和17.140之间,增长效应在0.438和5.0之间。研究结果同时显示,规模越大的城市通常具有更高的水平效应,但是增长效应却越低,这表明可能存在适度的最优城市规模。 相似文献
163.
The degree-one deformation of the Earth (and the induced discrepancy between the figure centre and the mass centre of the Earth) is computed using a theoretical approach (Love numbers formalism) at short timescales (where the Earth has an elastic behaviour) as well as at long timescales (where the Earth has a viscoelastic or quasi-fluid behaviour). For a Maxwell model of rheology, the degree-one relaxation modes associated with the viscoelastic Love numbers have been investigated: the Mo mode does not exist and there is only one transition mode (instead of two) generated by a viscosity discontinuity.
The translations at each interface of the incompressible layers of the earth model [surface, 670 km depth discontinuity, core-mantle boundary (CMB) and inner-core boundary (ICB)] are computed. They are elastic with an order of magnitude of about 1 mm when the excitation source is the atmospheric continental loading or a magnetic pressure acting at the CMB. They are viscoelastic when the earth is submitted to Pleistocene deglaciation, with an order of magnitude of about 1 m. In a quasi-fluid approximation (Newtonian fluid) because of the mantle density heterogeneity their order of magnitude is about 100 m (except for the ICB, which is in quasi-hydrostatic equilibrium at this timescale). 相似文献
The translations at each interface of the incompressible layers of the earth model [surface, 670 km depth discontinuity, core-mantle boundary (CMB) and inner-core boundary (ICB)] are computed. They are elastic with an order of magnitude of about 1 mm when the excitation source is the atmospheric continental loading or a magnetic pressure acting at the CMB. They are viscoelastic when the earth is submitted to Pleistocene deglaciation, with an order of magnitude of about 1 m. In a quasi-fluid approximation (Newtonian fluid) because of the mantle density heterogeneity their order of magnitude is about 100 m (except for the ICB, which is in quasi-hydrostatic equilibrium at this timescale). 相似文献
164.
The electricity generation capacity in the Limay River basin is approximately 26% of the total electrical power generation
in Argentina. Assessing the potential effects of climate change on the hydrological regime of this basin is an important issue
for water resources management. This study explores the presence of trends in streamflow series, evaluates climate sensitivity
and studies the effects on the flow regime of predicted changes in precipitation in the basin. In order to identify and quantify
changes in observed streamflow series, the Mann–Kendall test, with a modification for autocorrelated data, and an estimator
of the magnitude of the trend are applied. In order to evaluate the sensitivity of streamflow to changes in climate, the concept
of elasticity is used. Precipitation elasticity of streamflow is used to quantify the sensitivity of streamflow to changes
in precipitation and is estimated using a power law model and a linear statistical model in two sub-basins, Aluminé and Nahuel
Huapi. The effects on flow regime of the predicted changes in precipitation under different scenarios are studied. Climatic
results for different scenarios of growth in greenhouse gases from some General Circulation Models are used as inputs into
the proposed models. The analysis identifies decreasing trends in mean and minimum annual flows and in the low flow season.
The estimates of the precipitation elasticity imply that changes in precipitation produce similar changes in streamflow and
the climatic results for different scenarios show that the variations are moderate. 相似文献
165.
基于关键层理论的地表下沉盆地模型初探 总被引:1,自引:0,他引:1
目前,开采沉陷的研究主要是现场观测和以概率积分法为代表的开采沉陷预测。这些方法仅是对地表沉陷稳定后的现象进行观测和推断,不涉及对采场上覆岩层整体移动规律的研究。因长壁式布置工作面开采煤层的深厚比较大时,采场上覆岩层在靠近地表处会形成明显的弯曲带。在假设此弯曲带是控制地表沉陷及沉陷盆地最终形态的离地表最近一层主关键层且地表的下沉量远远小于该岩层厚度的基础上,用关键层位置的判别方法找出离地表最近一层关键层的位置后,用弹性薄板理论的半逆解法选择了较适合地表沉陷盆地形状的挠度函数,用薄板理论建立了缓倾斜煤层和倾斜煤层开采地表沉陷盆地力学模型,并对该模型的适用范围和参数进行了讨论。该模型考虑了影响地表下沉的多种因素,比概率积分法更具有理论意义。 相似文献
166.
本文根据中国西南部四个强震带残余应力场水平和铅直分布的测量和实验研究结果,讨论了古构造残余应力场对震源的作用:降低震源岩体强度,增大震源岩体形变,与现今应力场迭加在一起促成地震,随岩体破裂释放残余弹性能加到震源释放的现今弹性能中去提高震级和地震活动水平。 相似文献
167.
The purpose of the present article is to give a precise definition and analysis from first principals of anisotropy, as the term applies to elastic media, taking care to avoid unnecessary assumptions. Two fundamental concepts, material invariance and symmetry group of a material, are defined purely in terms of the stress-strain relation. The implications of material symmetry, or in other words, of anisotropy, for the structure of the stiffness tensor are then investigated. Using the reduced notation of Voigt, these results are presented as the well-known simplifications in the form taken by the six-by-six stiffness matrix that represents the material's stiffness tensor. A new, simple proof is given for the remarkable fact that an elastic medium cannot have rotational symmetry by an angle of less than 90° without being transversely isotropic. In addition, the mutual relation that the notions of elastic symmetry and crystal symmetry have with respect to the so-called orthogonal group is sketched. Despite the historical association between anisotropic elastic materials and the study of crystals, the given presentation shows that conceptually the notion of anisotropy in elastic media is entirely independent of that of crystal symmetry. 相似文献
168.
为了控制苏锡常地区的地面沉降,2000年开始该区实行了深层地下水的禁采。基于近10年来监测数据,对比分析了禁采前后地质环境要素的变化规律,重点剖析禁采后地下水回升条件下的土层变形特征。数据分析结果显示,禁采以来,以主采层第Ⅱ承压含水层为代表的地下水位逐步回升,自2000年至2009年,40m埋深水位降落漏斗面积由近4000km2缩小至1200km2。地面沉降的发展速率也出现不同程度的减缓,至2008年,大于5mm/a 的沉降区面积已缩减到1200km2。研究区土层的变形特征表现出明显的差异性。苏州北部沿江地区和中部地区地面沉降出现了明显回弹,土层表现为弹性变形特征。而位于地下水位漏斗和沉降漏斗中心附近的土层表现出沉降的迟滞性,即使在禁采后水位回升的情况下土层仍表现为持续沉降或微沉。研究结果为后续区域地面沉降模型中土层沉降模型的合理选择提供依据。 相似文献
169.
Hybrid time integration and coupled solution methods for nonlinear finite element analysis of partially saturated deformable porous media at small strain 下载免费PDF全文
The goal of the paper is to determine the most efficient, yet accurate and stable, finite element nonlinear solution method for analysis of partially saturated deformable porous media at small strain. This involves a comparison between fully implicit, semi‐implicit, and explicit time integration schemes, with monolithically coupled and staggered‐coupled nonlinear solution methods and the hybrid combination thereof. The pore air pressure pa is assumed atmospheric, that is, pa=0 at reference pressure. The solid skeleton is assumed to be pressure‐sensitive nonlinear isotropic elastic. Coupled partially saturated ‘consolidation’ in the presence of surface infiltration and traction is simulated for a simple one‐dimensional uniaxial strain example and a more complicated plane strain slope example with gravity loading. Three mixed plane strain quadrilateral elements are considered: (i) Q4P4; (ii) stabilized Q4P4S; and (iii) Q9P4; “Q” refers to the number of solid skeleton displacement nodes, and “P” refers to the number of pore fluid pressure nodes. The verification of the implementation against an analytical solution for partially saturated pore water flow (no solid skeleton deformation) and comparison between the three time integration schemes (fully implicit, semi‐implicit, and explicit) are presented. It is observed that one of the staggered‐coupled semi‐implicit schemes (SIS(b)), combined with the fully implicit monolithically coupled scheme to resolve sharp transients, is the most efficient computationally. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
170.