多个淹没水平圆柱诱发高阶谐波特性的数值与试验研究

基于势流理论采用时域高阶边界元方法建立了模拟非线性波浪与淹没水平双、三圆柱作用的数值水槽模型,其中采用混合欧拉-拉格朗日方法更新自由水面,四阶Runga-Kutta方法进行时间步进。利用两点法分离得到潜体下游高阶自由波,进而研究潜体间距、布置形式等对高倍频自由波的影响。同时在物理水槽内开展多潜体高阶谐波物理模型试验,并将试验结果与数值结果进行对比,吻合较好。研究发现:淹没双圆柱下游高阶谐波幅值随潜体间距呈现周期性振荡变化,其振荡的重现距离约为波长一半。而淹没三圆柱下游的高阶谐波随第一个间距呈周期性振荡变化,随第二个间距的增大而减小。     

喜马拉雅淡色花岗岩带伟晶岩的富铍成矿特点及向更高处找锂

喜马拉雅淡色花岗岩作为新识别的稀有金属成矿区带,已发现以Be-Nb-Ta(Sn-W)组合为主矿化且已形成大型矿床,如错那洞,但仅在为数不多的几处伟晶岩见到锂辉石,尚未发现工业锂矿床。因此,有必要剖析该区伟晶岩成矿(尤其Be同Li的对比)特点、条件及可能潜力,并与国内其他稀有金属矿带进行对比分析,从而推动喜马拉雅伟晶岩稀有金属矿床尤其是锂矿的发现。该区伟晶岩母体淡色花岗岩与华南稀有金属矿化花岗岩类似,显示高的分异程度但较窄的演化区间,并且熔体具有高的Li浓度。在印亚大陆碰撞带复杂的构造-变质-深熔作用下产生了多期次的岩浆活动,尤其新喜马拉雅期巨量的岩浆可为伟晶岩的形成、远距离迁移分异及成矿提供有利的热和物质基础。基于含Li伟晶岩形成于"远"母体、"高"海拔的特点,提出区域构造层位的上部或更高海拔地区以及淡色花岗岩岩体外侧远端的围岩内将可能是含锂伟晶岩的就位空间与找矿重点地段。     

Numerical storm surge model with higher order finite difference method of lines for the coast of Bangladesh

In this study, the method of lines (MOLs) with higher order central difference approximation method coupled with the classical fourth order Runge-Kutta (RK(4,4)) method is used in solving shallow water equations (SWEs) in Cartesian coordinates to foresee water levels associated with a storm accurately along the coast of Bangladesh. In doing so, the partial derivatives of the SWEs with respect to the space variables were discretized with 5-point central difference, as a test case, to obtain a system of ordinary differential equations with time as an independent variable for every spatial grid point, which with initial conditions were solved by the RK(4,4) method. The complex land-sea interface and bottom topographic details were incorporated closely using nested schemes. The coastal and island boundaries were rectangularized through proper stair step representation, and the storing positions of the scalar and momentum variables were specified according to the rules of structured C-grid. A stable tidal regime was made over the model domain considering the effect of the major tidal constituent, M₂ along the southern open boundary of the outermost parent scheme. The Meghna River fresh water discharge was taken into account for the inner most child scheme. To take into account the dynamic interaction of tide and surge, the generated tidal regime was introduced as the initial state of the sea, and the surge was then made to come over it through computer simulation. Numerical experiments were performed with the cyclone April 1991 to simulate water levels due to tide, surge, and their interaction at different stations along the coast of Bangladesh. Our computed results were found to compare reasonable well with the limited observed data obtained from Bangladesh Inland Water Transport Authority (BIWTA) and were found to be better in comparison with the results obtained through the regular finite difference method and the 3-point central difference MOLs coupled with the RK(4,4) method with regard to the root mean square error values.     

Study of the Impact of Industrial Emission on the Vegetation Grown Around Huelva (South of Spain) City

This paper reports the spatial pollution variability, obtained by using vegetal samples for biomonitoring atmospheric pollution around one of the most industrialized areas in the southwestern Spain (Huelva), through the study of the impact of industrial emissions on two Mediterranean species: Pinus pinea L. and Nerium oleander L.Samples were collected during spring of 2002, at different distances (0.5, 1, 2, 4, 6, 8 km) along two transects running to the dominant wind directions from the industrial complex and another against wind direction. Leaves and branches of the two species, together with soil samples were collected at each site. The concentration of Cu, Pb and Zn was determined by simultaneous inductively coupled plasma mass spectrometry (ICP/MS). Two principal emission sources of pollution were identified, one from industrial focus that markedly affects the level of Cu and Zn in the vicinity (0.5–1 km) of the industrial complex, and another one from secondary anthropogenic activities that are responsible of the high level of Cu, Pb and Zn. P. pinea is a better biomonitor of Zn than N. oleander. Pine needles are better biomonitors of Zn pollution than bark because of their physicochemical characteristic.     

关于数值求解卫星运动微分方程中的一个问题

本文阐明地球非球形引力位中的高阶次球谐项（ 即“短”波项） 对求解卫星运动微分方程的两类数值方法（ 单步法和多步法） 选择积分步长的不同影响,并以实际算例证实这一点。     

测绘成人高等函授教育档案管理工作的的工作要点

在测绘成人高等函授教育中,档案管理是函授站的一项重要工作。要做好档案管理工作,必须加强档案管理人员的思想政治教育和科学文化水平,提高他们的政治理论水平,思想道德素养,科学管理能力和档案管理基本技能。     

Kolb's Experiential Learning Theory and Its Application in Geography in Higher Education

Abstract

Kolb's experiential learning theory is one of the best known educational theories in higher education. The theory presents a way of structuring a session or a whole course using a learning cycle. The different stages of the cycle are associated with distinct learning styles. Individuals differ in their preferred learning styles, and recognizing this is the first stage in raising students' awareness of the alternative approaches possible. This article presents some case studies of ways in which the theory can be applied in university geography.     

“学生化”的城中村社区——基于广州下渡村的实证分析

学生化作为绅士化现象的一种类型,是高等教育规模扩张背景下学生群体对于城市空间进行重构的现象。起因于学生群体的居住偏好,以及投资者与房屋所有者的寻租行为,面向学生群体的居住空间开始产生并聚集,形成独特的学生化社区,并由此产生一系列的社会,经济与文化影响。基于对学生化现象相关研究的综述,本文对于广州市中山大学邻近的下渡村学...     

Dynamics of dimensions in factor-space cosmology

For multi-dimensional cosmological models we investigate the dynamics of both, scales and dimensions. The classical equation of motions and the corresponding Wheeler-de Witt equation are set up generally and the qualitative behaviour of the system is discussed for some specific model with 2 factor spaces: A space M₁ with dynamical dimension, and a compact internal space M₂ of constant dimension. With a natural choice of some contraint, there exist a solution where M₁ expands as usual space while M₂ is shrinking down to unobservable scales.