流体饱和两相多孔介质动力反应计算分析

基于流体饱和两相多孔介质的弹性波动方程组,运用显式逐步积分格式与局部透射人工边界相结合的时域显式有限元方法对该波动方程组进行求解,对两相介质在输入地震波作用下的弹性动力反应进行计算和分析;对在是否考虑孔隙流体渗流的两种情况下计算得到的两相介质弹性动力反应结果的差异进行对比研究,从而揭示孔隙流体渗流对两相介质动力反应性质的影响。计算结果表明：两相介质弹性动力反应时程的波形与入射地震波的波形相同,且弹性动力反应的峰值出现的时刻对应于入射地震波的峰值出现的时刻;孔隙流体的渗流将对两相介质的弹性动力反应性质产生显著的影响。数值计算同时表明,时域显式有限元方法是进行流体饱和两相多孔介质弹性动力反应计算分析的一种有效的方法。     

桩-土相互作用影响的模型试验研究

通过将模型试验、现场实测的结果与弹性理论解进行对比,指出弹性理论解夸大了桩-桩、桩-土、土-土相互作用影响,造成沉降计算值偏大和过高估计桩顶反力的不均匀性（或筏底地基土反力的不均匀性）,并提出对弹性理论解进行修正的途径和方法。     

Insights from a Simple Hotelling Model of the World Oil Market

This paper uses annual data on world oil price and consumption from 1965 to 2006 to calibrate a Hotelling model of optimal nonrenewable resource extraction. Numerical solutions are generated for various specifications of the elasticity of demand for both isoelastic demand and linear demand under each of two possible market structures: perfect competition and monopoly. Prior to the 1973 oil crisis, the model that best fits actual data is one of perfect competition with linear demand and a demand elasticity of −0.4. For the periods 1973–1981 and 1981–1990, the model that best fits actual data is one of monopoly with linear demand and demand elasticities of −0.8 and −0.7, respectively, suggesting that the market was strongly influenced by OPEC during this time. Under the model that best fits the most recent period (perfect competition with linear demand and demand elasticity −0.5), the real oil price (in 1982–1984 U.S.$) should fall in the range $60.87–$66.31/barrel over the years 2010–2030.

抗浮锚杆应力-应变状态的线弹性理论分析

假定抗浮锚杆各部分贡献的位移与锚杆轴力均呈线弹性关系,运用力学原理分析锚杆轴力与锚侧摩阻力、锚-土变形之间的相互关系,推导出锚杆的摩阻力、轴力及各部分变形与锚杆各参数的相互关系。实例验证结果表明：基于线弹性模型基础上建立的摩阻力、轴力和位移公式能够较好地描述垂向抗浮锚杆在弹性变形阶段的内力和变形形态;获得了抗浮锚杆摩阻力和剪切位移沿锚固长度的分布规律;证实了锚土界面处变形为土层抗浮锚杆变形的主要部分。     

地震孕育过程准静态模型激发扰动电磁场问题

以磁热弹性理论为工具,讨论与地热有关的三维准静态问题: 载热流体侵入竖直或水平裂隙的情况和存在静态局部高温区的情况。在求得其近似解后,着重讨论其扰动磁场的时空分布。最后指出其在地震理论研究中的应用。     

天山北坡西部雪岭云杉海拔梯度生态弹性变化

基于天山北坡西部温泉哈夏林区间隔100m海拔高度采集的雪岭云杉梯度样本的断面积生长量资料,分析该区域树木生态弹性变化。干旱事件是区域生态弹性最主要的干扰因子,高温事件也是干扰因子之一。干扰因子的强度会造成生态弹性梯度特征的变化。在极端干旱年份,哈夏林区梯度生长弹性特征最显著,即中高海拔为强抵抗力和弱恢复力,而低海拔则呈相反态势,并出现生长衰退现象。中旱事件时不同海拔均为强抵抗力和较强的恢复力。高温年份低海拔呈现弱抵抗力和弱恢复力。在发生持续干旱时,不同海拔高度的树木生长均受到遏制,但低海拔衰退强度大于高海拔区域,高海拔区域树木对干旱的适应能力要强于中低海拔。     

A micromechanically derived anisotropic micropolar constitutive law for granular media: Elasticity

In the present work, it is attempted to derive a macroscopic constitutive law for the elastic deformation of granular materials, based on microscopic considerations. For the sake of simplicity, the solution is restricted to two dimensions, that is, a random assembly of infinitely extended cylinders. After examining pairwise contact interactions, the elastic energy rate of the assembly is retrieved in a discrete form. Introducing the probability density function of the contact orientations, the continuum form of the elastic energy density rate is evaluated as a function of generalized strains and curvatures, and their rates. The stresses and couple stresses result as dual variables to the generalized strain and curvature rates. Some properties of the resulting model are discussed, examples are presented and conclusions are drawn.Copyright © 2014 John Wiley & Sons, Ltd.     

中国员工激励的理论模式探讨

探讨企业员工激励的必要条件,员工的需求变化层次,以及个体激励与群体激励的相互关系.     

Shear strength characteristics of Irbid clayey soil mixed with iron filling and iron filling–cement mixture

Iron filling and iron filling–cement mixture were used to improve the shear strength characteristics of Irbid clayey soil. For this purpose, five types of Irbid clay soils were obtained and mixed with iron filling and iron filling–cement mixture at different percentages. Two sets of prepared samples were mixed with the admixture. The first set was prepared by mixing the soil samples with iron filling alone at 2.5, 5.0, 7.5, and 10% by dry weight of the soil. The second set was prepared by mixing with iron filling–cement mixture at equal ratio of the same percentages of the first set. An unconfined compression test was performed in this study to measure the shear strength properties of the soils. The test results showed that the increase in the percentages of the iron filling and iron filling–cement mixture up to 10% will result in increasing the maximum dry density of the soil and increase the unconfined compressive strength and the secant of modulus of elasticity of the clayey soil. Also, the addition of iron filling–cement mixture increased the unconfined compressive strength and secant modulus of elasticity of the clayey soil higher than the addition of iron filling alone.     

A physically-based model of long-term food demand

Reducing hunger while staying within planetary boundaries of pollution, land use and fresh water use is one of the most urgent sustainable development goals. It is imperative to understand future food demand, the agricultural system, and the interactions with other natural and human systems. Studying such interactions in the long-term future is often done with Integrated Assessment Modelling. In this paper we develop a new food demand model to make projections several decades ahead, having 46 detailed food categories and population segmented by income and urban vs rural. The core of our model is a set of relationships between income and dietary patterns, with differences between regions and income inequalities within a region. Hereby we take a different, more long-term-oriented approach than elasticity-based macro-economic models (Computable General Equilibrium (CGE) and Partial Equilibrium (PE) models). The physical and detailed nature of our model allows for fine-grained scenario exploration. We first apply the model to the newly developed Shared Socio-economic Pathways (SSP) scenarios, and then to additional sustainable development scenarios of food waste reduction and dietary change. We conclude that total demand for crops and grass could increase roughly 35–165% between 2010 and 2100, that this future demand growth can be tempered more effectively by replacing animal products than by reducing food waste, and that income-based consumption inequality persists and is a contributing factor to our estimate that 270 million people could still be undernourished in 2050.