晾晒气象指数预报

室外晾晒条件的优劣，取决于日蒸发量的大小。根据这一思路，分析了影响日蒸发量的因子及其与蒸发量的关系，建立了日蒸发量预报方程，并根据不同季节日蒸发量的大小，确定了晾晒指数。     

风的动力作用

本文从工程角度出发，阐述了风谱的表达、意义及应用，并对风载荷的稳态及脉动部分都进行了讨论，脉动风载荷的计算与前人不同，文中保留了和频项的贡献，对风载荷的各组成部分提供了量的概念。结果表明，风载荷的脉动峰值有可能是平均值的２．３６倍，利用阵风风速计算出的风载荷，数量上接近风载荷的±值，一阶与二阶风载荷的脉动频率都极低，对低频系统应加以注意。     

Study on semi-active control of mega-sub controlled structure by MR damper subject to random wind loads

The recently proposed mega-sub controlled structure （MSCS）, a new type of structure associated with the design and construction of super-tall buildings, has attracted the attention of designers for use in enhancing the control effectiveness in mega-frame buildings. In this paper, a dynamic equation and method to assemble parameter matrixes for a mega-sub controlled structure under random wind loads is presented. Semi-active control using magnetorheological dampers for the MSCS under random wind loads is investigated, and is compared with a corresponding system without dampers. A parametric study of the relative stiffness ratio and relative mass ratio between the mega-frame and the substructures, as well as the additional column stiffness ratio that influences the response control effectiveness of the MSCS, is discussed. The studies reveal, for the first time, that different control mechanisms exist. The results indicate that the proposed structure employing semi-active control can offer an effective control mechanism. Guidelines for selecting parameters are provided based on the analytical study.     

土地利用动态与风力侵蚀动态对比研究——以内蒙古自治区为例

内蒙古是我国土壤风力侵蚀较为严重的地区之一,同时也是我国土地利用方式剧烈变化的地区之一。依据两期土地利用数据以及相应年代的土壤风力侵蚀数据,研究了20世纪90年代末期内蒙古自治区土地利用和风力侵蚀的静、动态格局。根据土地利用和风力侵蚀的空间分布及动态变化特点,设计了内蒙古土地利用-风力侵蚀动态区划,基于该区划详细讨论了内蒙古不同地区占主导地位的土地利用动态与风力侵蚀动态,由此揭示了两者之间存在的驱动--被驱动关系。研究发现,在20世纪90年代末期,内蒙古土地利用和风力侵蚀的基本格局没有太大变化,但风力侵蚀强度在总体上增强了;土地利用的变化主要反映为草地的退化和耕地的扩张。土地利用动态与风力侵蚀动态有着良好的时空对应关系:草地的退化与耕地的扩张导致了显著的风力侵蚀增强,而草地的改善以及耕地的收缩对风力侵蚀的影响不如前者明显,这表明了土地利用动态对风力侵蚀动态正、反向驱动的不平衡性。     

中国沙尘事件的区域特征

AsevereduststormoccurredoverEastAsiainthemiddletendaysofApril1998.Afteroneweek,itsdustplumeaffectedthecontinentofNorthAmerica.Thisattractedtheattentionofmanyscientistsintherelatedcountriestoduststorms.InrecentyearsthenumberofduststormshasbeenincreasinginChina.Itisnotonlyanimportantsymptomofdesertificationfromslowerchangetofasterchange,butalsoareflectionofthesynthesisofenvironmentalstates,includingclimate,ecosystemandsoil,whicharealldeterioratingtosomedegrees.AccordingtothedefinitionofMeteo…     

柴达木盆地东北部哈勒腾河流域风况特征及其对风沙地貌发育的影响

风况是影响风沙地貌发育的重要因子,在一定程度上决定了沙丘类型.为探究区域风沙地貌发育与风况之间的关系,对哈勒腾河流域不同区域一个完整年度的风况进行分析.结果表明:流域年平均风速为2.78 m·s-1,起沙风集中在春夏季,平均风速为7.78 m· s-1,起沙风事件平均持续时间为4.1 h;流域输沙势122-254 VU...     

风力发电机对荒漠草原地表温度及蒸散发的影响

以内蒙古朱日和风电场为例,利用Landsat 5及Landsat 8数据对风力发电机建设前后的地表温度(LST)及蒸散发(ET)进行了模拟,并统计了风力发电机所在位置与周围8个相邻像元、以及风力发电机240 m缓冲区范围内的LST、ET均值及显著性差异,以此来判断风力发电机对荒漠草原地表温度及蒸散发的影响程度.本文结论...     

关于风力发电场风机光影影响防护距离的研究

风力发电场的建设,极大地推动了地方经济的发展;但如果风机布置不科学,极有可能对周围民宅产生光影闪烁影响。关于风力发电场风机的光影闪烁影响预测,国家目前尚无相应的标准和规范,也无可借鉴资料。综合分析了辽宁省环境工程评估审核中心所评估的个例环评报告,初步探讨了风机产生的光影闪烁影响的各种情况,提出了风机光影影响防护距离的概念和计算方法。     

A modification to the Munk wind-driven ocean circulation theory

In order to fulfill the no-slip condition at the western and eastern boundaries of the ocean basin, introduced ＂effective wind stress＂, which has much larger spatial variations towards the boundaries than in the ocean interior. The effective wind stress can thus be decomposed into spatially slow-varying and fast varying components. Careful scale analysis on the classical Munk winddriven ocean circulation theory, which consists of the interior Sverdrup flow and the western boundary current but of no eastern boundary current, shows that the wind stress curl appearing in the Sverdrup equation must have negligible spatial variations. In the present model the spatially slow-varying component of the wind stress appears in the Sverdrup equation, and the spatially fastvarying component becomes the forcing term of the boundary equations. As a result, in addition to the classical Munk solution the present model has an extra term at the western boundary which （Northern Hemisphere） increases the northward transport as well as the southward return transport, and has a term at the eastern boundary corresponding to the eastern boundary current.     

Approximate solution for mechanism of thermally and wind-driven ocean circulation

The thermally and wind-driven ocean circulation is a complicated natural phenomenon in the atmospheric physics. Hence we need to reduce it using basic models and solve the models using approximate methods. A non-linear model of the thermally and wind-driven ocean circulation is used in this paper. The results show that the zero solution of the linear equation is a stable focus point, which is the path curve trend origin point as time (t) trend to infinity. By using the homotopic mapping perturbation method,...