北京市水资源利用与经济增长动态关系研究——基于VAR与SVAR模型分析

基于1990—2012年北京GDP数据和三次产业用水量数据,进行GDP数据与三次产业用水量的平稳性检验和协整检验,检验通过后,对四组数据构建SVAR模型,利用脉冲响应函数,分析北京GDP与三次产业用水量之间的相互关系,结果显示第一产业用水量、第二产业用水量与北京GDP的增长负相关,第三产业用水量与北京GDP的增长正相关.     

西藏农村人力资本投资困境分析

农村人口综合素质整体不高,日益成为西藏农村反贫困和可持续发展的重要制约因素之一,加大人力资本投资日益迫切.文章提出没有基于本地化的农村办学思路,师资队伍整体落后与教育质量不高长期并存,教育投资观念偏差根深蒂固,基层卫生服务能力薄弱及健康知识普及严重不足等是当前西藏农村人力资本投资存在的诸多困境,并指出尽快优化教育发展结构、突出师资队伍建设、加强成人培训力度、关注妇女儿童健康是提高农村人口发展能力的重要途径.     

位于强震区的农村中小学教学楼砌体结构抗震设计分析

针对大开间少墙砌体结构的受力特点，结合教学楼震害，分析了构造柱、圈梁对砌体结构抗震性能的影响，并对提高结构延性的设计理念进行了阐述；同时对大开间少墙单面走廊砌体结构的设计提出了几点建议。     

Optimal multi-asset investment with no-shorting constraint under mean-variance criterion for an insurer

This paper considers the optimal investment strategy for an insurer under the criterion of mean-variance. The risk process is a compound Poisson process and the insurer can invest in a risk-free asset and multiple risky assets. This paper obtains the optimal investment policy using the stochastic linear quadratic (LQ) control theory with no-shorting constraint. Then the efficient strategy (optimal investment strategy) and efficient frontier are derived explicitly by a verification theorem with the viscosity solution of Hamilton-Jacobi-Bellman (HJB) equation.     

水钢高炉最佳炉料结构的试验

采用正交试验方法研究了现有原燃料及设备条件下水钢高炉的最佳炉料结构;在此基础上进一步优化炉料结构,并对它们的冶金性能进行了试验.结果表明:目前水钢高炉最佳炉料结构为86%的烧结矿(二元碱度为1.8)配加14%的印度块矿与越南块矿的混合矿(混合比例为1:1);此种炉料结构的软熔性能好,还原性能达到优良水平,炉渣碱度合适,但低温还原粉化性能不佳;若采用二元碱度为1.7的烧结矿,使炉渣的碱度低于1.2,则熟料率达到90%的炉料结构是完全可行的.     

基于16S rRNA和16S-23S rRNA基因间隔区序列探讨陆生和水生螺原体菌株的系统发生关系

采集江苏省养殖池塘内发病的中华绒螯蟹、克氏原螯虾和南美白对虾,利用已有螺原体16S rRNA和23S rRNA基因序列保守引物扩增并测序16S rRNA和16S-23S rRNA基因间隔区序列(ISRs).基于已获得的序列和GenBank中下载的螺原体序列分别进行同源性比对,比对的结果分别利用PAUP软件和MrBaye...     

Exploring non-equilibrium statistical ensembles

Since Gibbs synthesized a general equilibrium statistical ensemble theory, generalizing the Gibbsian theory to non-equilibrium phenomena has been a dream for some theorists. However, the status of the theory for the non-equilibrium ensemble formalism is not as well established as the Gibbsian ensemble theory. In this work, we explore the formalism behind the non-equilibrium statistical ensemble theory based on the sub-dynamic kinetic equation originating from the Brussels-Austin school and develop...     

广东南雄断裂带Ar-Ar年龄及其地质意义

 南雄断裂带是一条大型的拉伸剥离断层。在详细的野外调查和岩石样品镜下观察的基础上,对南雄断裂带糜棱岩中的同构造变形-变质矿物白云母进行了Ar-Ar法同位素年龄测定。年代学研究结果表明,南雄断裂带作为拉伸剥离正断层活动开始于早白垩世（117.3±2.7 Ma）,而其强烈的伸展变形韧性剪切发生在早白垩世末～晚白垩世初（Ar-Ar坪年龄为94.6±0.4 Ma）,随后在88.9±1.0 Ma和81.1±2.0 Ma还可能发生过2次较明显的热扰动事件。南雄断裂带Ar-Ar年龄数据为进一步判断华南白垩纪岩石圈伸展作用发生的时间提供了新的热年代学制约,即是说,早白垩世末～晚白垩世初是区域岩石圈伸展的重要时期。     

Jamming by shear

A broad class of disordered materials including foams, glassy molecular systems, colloids and granular materials can form jammed states. A jammed system can resist small stresses without deforming irreversibly, whereas unjammed systems flow under any applied stresses. The broad applicability of the Liu-Nagel jamming concept has attracted intensive theoretical and modelling interest but has prompted less experimental effort. In the Liu-Nagel framework, jammed states of athermal systems exist only above a certain critical density. Although numerical simulations for particles that do not experience friction broadly support this idea, the nature of the jamming transition for frictional grains is less clear. Here we show that jamming of frictional, disk-shaped grains can be induced by the application of shear stress at densities lower than the critical value, at which isotropic (shear-free) jamming occurs. These jammed states have a much richer phenomenology than the isotropic jammed states: for small applied shear stresses, the states are fragile, with a strong force network that percolates only in one direction. A minimum shear stress is needed to create robust, shear-jammed states with a strong force network percolating in all directions. The transitions from unjammed to fragile states and from fragile to shear-jammed states are controlled by the fraction of force-bearing grains. The fractions at which these transitions occur are statistically independent of the density. Jammed states with densities lower than the critical value have an anisotropic fabric (contact network). The minimum anisotropy of shear-jammed states vanishes as the density approaches the critical value from below, in a manner reminiscent of an order-disorder transition.