摘要：Cobalt nanoparticles(NPs)catalysts are extensively used in heterogeneous catalytic reactions,and the addition of alkali metal promoters is a common method to modulate the catalytic performance because the catalyst's surface structures and morphologies are sensitive to the addition of ***,the underlying modulation trend remains ***,the adsorption of alkali metal promoters(Na and K)on the surfaces of face-centered-cubic(FCC)and hexagonal-closest packed(HCP)polymorphous cobalt was systematically investigated using density functional ***,the effect of alkali promoters on surface energies and nanoparticle morphologies was revealed on the basis of Wulff *** FCC-Co,the exposed area of the(111)facet in the nanoparticle increases with the adsorption coverage of alkali metal ***,the(311),(110),and(100)facets would disappear under the higher adsorption coverage of alkali *** HCPCo,the Wulff morphology is dominated by the(0001)and(1011)facets and is independent of the alkali metal adsorption *** work provides insights into morphology modulation by alkali metal promoters for the rational design and synthesis of cobalt-based nanomaterials with desired facets and morphologies.

摘要：设计并研究了一种周期性多层金属/介质层结构以获得太赫兹频段的阻带滤波器.通过利用极化综合效应实现了一个大带宽的阻带.这一阻带滤波器的带宽可以通过调制银层的电磁耦合作用进行调节.同时还研究了金属层的数量、晶格常数和介质层的介电常数对阻带滤波器的中心频率和带宽的影响.通过合理调配这些因素可以调制中心频率蓝移和带宽增大.通过耦合作用调制带宽的方法可为设计大带宽阻带滤波器提供好的思路.

摘要：干旱是一种世界范围的自然灾害,长期影响各国农业生产和社会经济活动。"一带一路"沿线区域生态环境脆弱、农业耕地集中、干旱灾害频繁,利用遥感卫星监测大区域的干旱水平及其时空变化,对于科学掌握"一带一路"地区的干旱格局、区域分异特征,及其对农业耕地的影响具有重要的科学和现实意义。本文基于TRMM降水数据,利用降水距平百分率干旱模型研究和获取了N50°以南的"一带一路"沿线地区1998-2015年逐月干旱时空分布,得知冬季的干旱主要分布在东北亚、东南亚和南亚地区,夏季的干旱主要分布在中亚和西亚地区,干旱的发生具有明显的季节周期性。利用BFAST算法以经济走廊为骨干划分六大片区分析了"一带一路"地区干旱的区域分异特征,可知18年来,东北亚、西亚北非、南亚和中东欧地区的干旱平均水平呈现小范围的减轻趋势,中亚地区的干旱平均水平呈现小范围的增强趋势,东南亚地区的干旱平均水平变化呈现先减后增的波动特征。1998-2015年间"一带一路"地区的干旱总面积以每年40260 km^2的总趋势不断减少。