敞开酸溶-电感耦合等离子体光谱法测定钨矿石和钼矿石中微量元素

钨矿石和钼矿石具有丰富的共生或伴生元素,检测共生或伴生元素的含量有利于矿产资源的综合利用.在国家标准方法中钨矿石和钼矿石的共生或伴生元素含量是按元素分别检测,效率很低.本文在敞开体系中用盐酸+硝酸+氢氟酸+高氯酸消解样品,以7％盐酸溶解盐类,电感耦合等离子体发射光谱同时测定钨矿石和钼矿石中铋、钴、铜、锂、镍、磷、铅、锶、钒、锌等10种微量元素.选定了各元素的分析谱线和光谱级次,采用离峰背景校正法消除背景干扰,干扰元素校正系数法消除元素间的谱线重叠干扰.方法检出限为1.43 ～ 18.8 μg/g,加标回收率为90％ ～ 110％.经钨矿石和钼矿石标准物质分析验证,测定结果与标准值基本吻合,方法精密度(RSD,n=10)小于8％.该方法克服了碱熔引入大量碱金属元素以及可能引入杂质的缺陷,又不用处理钨酸和钼酸沉淀,能快速测定钨矿石和钼矿石中微量共生或伴生元素.     

硬玉的差热分析和紫外荧光光谱研究

通过对缅甸硬玉的差热分析和紫外荧光光谱研究，发现不同颜色硬玉的紫外荧光谱中的617nm处的谱峰，可能是Cr引起的；对不同颜色硬玉进行的差热分析表明，其熔融温度略有不同，说明其生长环境有一定差异，而硬玉也可能是较好的耐热材料，具一定的开发潜能。     

孤立冰块流拖曳系数的优化辨识

流拖曳系数是海冰动力学模型中的重要参数,实际海冰运动时受到水流的底面剪切作用和侧面正压力作用,相应的拖曳系数分别为摩拖曳系数和形拖曳系数。利用实验室波流水槽设备,对长方平底、长方粗糙底和圆饼型淡水冰试样进行拖曳运动试验,获得26组冰样运动数据。根据这些试验数据,利用动量法原理和数学优化方法构造了摩拖曳系数和形拖曳系数的辨识模型,将摩拖曳系数和形拖曳系数两项分开。在此基础上,分析了冰样粗糙度指标(支承长度率和冰厚均方根偏差)对这两个系数的影响;发现了摩拖曳系数同冰样水平尺寸和垂直尺寸之比的关系,该关系能将冰山和浮冰的摩拖曳系数归结到同一条曲线上。     

关于部分变元的非常稳定性

本文利用极限方程的方法研究微分方程关于部分变元的多种非常稳定性,讨论了给定方程与其积限方程的非常稳定性的关系。     

近40年来甘肃省降水的变化特征

利用1960—2003年甘肃省59个测站逐日降水资料,研究了甘肃省四季和年降水量及雨日的气候变化特征。结果表明,平均年降水量和雨日的空间分布非常相似。河西和白银市的年降水量的趋势系数为正,省内其它地区为负;河西大部和甘南部分地区的年雨日的趋势系数为正,省内其它地区为负。线性倾向估计的结果表明,年降水量线性倾向值的零线基本以黄河为界,河西在增加,河东在减少,减少最明显的区域在徽县和康县盆地;雨日增加主要在河西西部偏南地区、沿祁连山的大部分地区及临夏以及甘南等海拔相对较高的地区,中部和陇东南的雨日在减少。雨日增多的地方降水量也在增加,反之亦然。全省年降水量和年雨日在1990年代均为低谷,而在21世纪初又都有上升趋势。降水量突变在1990年代中期;雨日突变河西在1960年代后期,河东在1970年代后期和1990年代中期。冬季降水量及雨日表现全省性大范围的增加趋势,秋季降水量及雨日亦呈全省性减少趋势;而春、夏季的降水量及雨日变化趋势则是地区性的。     

A new approach to assessing the water footprint of hydroelectric power based on allocation of water footprints among reservoir ecosystem services

Hydroelectric power is an important energy source to meet the growing demand for energy, and large amounts of water are consumed to generate this energy. Previous studies often assumed that the water footprint of hydroelectric power equaled the reservoir’s water footprint, but failed to allocate the reservoir water footprint among the many beneficiaries; dealing with this allocation remains a challenge. In this study, we developed a new approach to quantify the water footprint of hydroelectric power (WF_h) by separating it from the reservoir water footprint (WF) using an allocation coefficient (η_h) based on the ratio of the benefits from hydroelectric power to the total ecosystem service benefits. We used this approach in a case study of the Three Gorges Reservoir, the world’s largest reservoir, which provides multiple ecosystem services. We found large differences between the WF_h and the water footprint of per unit of hydroelectric production (PWF_h) calculated using η_h and those calculated without this factor. From 2003 to 2012, η_h decreased sharply (from 0.76 in 2005 to 0.41 in 2012), which was due to the fact that large increases in the value of non-energy ecosystem services, and particularly flood control. In 2009, flood control replaced hydroelectricity as the largest ecosystem service of water from the Three Gorges Reservoir. Using our approach, WF_h and PWF_h averaged 331.0 × 10⁶ m³ and 1.5 m³ GJ⁻¹, respectively. However, these values would almost double without allocating water footprints among different reservoir ecosystem services. Thus, previous studies have overestimated the WF_h and PWF_h of reservoirs, especially for reservoirs that serve multiple purposes. Thus, the allocation coefficient should not be ignored when calculating the WF of a product or service.     

A review on stochastic differential equations for applications in hydrology

Fundamentals of the theory of stochastic calculus and stochastic differential equations (SDE's) which are finding increasing application in water resources engineering are reviewed. The basics of probability theory, mean square calculus and the Wiener, white Gaussian and compound Poisson processes are given in preparation for a discussion of the general Itô SDE with drift, diffusion and jump discontinuity terms driven by Gaussian white noise and compound Poissionian impulses. Also discussed are stochastic integration and the derivation of moment equations via the Itô differential rule. The lierature of SDE's is reviewed with an emphasis on the more accessible sources.     

Predicting the displacement of triple pendulum™ bearings in a full‐scale shaking experiment using a three‐dimensional element

The accuracy of a series spring model to predict the peak displacement and displacement history of Triple Pendulum? (TP) bearings in a strongly shaken, full‐scale building is evaluated in this paper. The series spring model was implemented as a self‐contained three‐dimensional TP bearing element in OpenSees and is now available for general use. The TP bearing element contains the option for constant friction or a generalized friction model that accounts for the effect of instantaneous velocity and compression load on the friction coefficient. Comparison between numerical simulation and experimental data of a five‐story steel moment frame building shows that the peak displacement of isolation system can generally be predicted with confidence using a constant friction coefficient model. The friction coefficient model accounting for the effect of axial load and velocity leads to minor improvement over the constant friction coefficient models in some cases. Copyright © 2013 John Wiley & Sons, Ltd.     

热水条件下角闪石断层泥的摩擦滑动性质——与斜长石断层泥的对比

基于速率与状态依赖性摩擦本构关系理论框架,在热水条件下研究了角闪石断层泥的摩擦滑动性质并与闪长岩的另一种主要矿物斜长石的摩擦滑动性质进行了对比.摩擦实验是在三轴实验系统上完成,有效正应力200 MPa,孔隙压力30 MPa,并将加载速率在1.22 μm/s和 0.122 μm/s之间实施了切换.结果表明角闪石的摩擦系数均值为0.70±0.01,随着温度增加没有系统性的变化,整体低于斜长石的摩擦系数(0.75±0.01);计算与实验表明,角闪石和斜长石的摩擦系数的体积分数加权平均值与闪长岩的摩擦系数基本一致;角闪石在实验温度范围内(100～614 ℃)显示速率强化(a-b>0),与斜长石在整个温度范围内的速率弱化(a-b<0)正好相反;角闪石的速率依赖性在整个实验温度范围内无系统性的变化.     

基于Theil指数的广东省入境旅游经济时空差异研究

运用Theil指数定量评价了1990-2009年广东省入境旅游经济时空尺度上的市际、地带间和地带内差异变化状况,其结论如下:(1)在时间尺度上,广东入境旅游经济市际差异Tp、地带内差异Twr演变呈逐渐收敛趋同的阶梯状下降趋势;珠三角地带间及地带内差异也呈阶梯状下降,东翼、西翼、山区地带间及地带内演变趋势不明显.(2)在空间尺度上,广东省入境旅游经济发展存在非均衡性,市际差异Tp主要来源于地带内差异Twr的贡献,尤其是珠三角地带内差异的贡献;珠三角与东翼、西翼、山区地带间差异较大,而东翼、西翼、山区地带间差异很小,地带间差异Tbr指数珠三角＞东翼＞山区＞西翼.引入区域分离Separation(缩写为SEP)指数来定量比较广东省四大地带入境旅游经济分离收敛的空间变化规律,并对广东省入境旅游经济发展提出相关建议.