解扩散方程初边值问题的数值边界元积分方程法

在应用中(如数值天气预报等),经常需要对时空偏微分方程进行数值求解,通常大多采用有限差分计算或有限元法,虽然它们是应用得最广的数值解法(如差分方法),但也有某些局限和不足,本文提出了一种边界元积分方程法。作为示例,我们对扩散方程的初边值问题进行了基本原理和方法的讨论,其基本思想是通过积分变换,消除对时间的依赖性,再在变换空间中,用边界元法对积分后的方程进行数值处理,最后用数值逆变换以完成该问题的数值求解,本方法可对更为复杂的依赖于时间的方程进行类似处理,它具有不同于传统有限差分法和有限单元法特点的优越性,可供有关工作者解初边值问题试用和参考。     

Adomian分解法在完全非线性S-G方程中的运用

为分析具有高非线性强度下的偏微分方程的初值问题,简化变量分离等方法带来的繁杂计算,研究了一类完全非线性Sine-Gordon方程以及它的近似方程(在|up|很小的情况下),经过适当的函数变换,运用改进的Ado-mian分解法解决了一些特殊情况下它们的初值问题,结合Talyor级数展开式,得到了一些精确解:扭结解(kink)、紧孤子解(compacton)、多重紧孤子解、compacton-kink解.另外运用线性化的方法结合不同形式的解得到它们一些更加丰富的新形式的精确解.     

振荡型Rossby孤立波与大气阻塞

从正压涡度方程出发,在弱非线性和弱基流切变条件下,导得了描述非线性大气长波活动的推广的Ｋｄｖ方程,并得到了方程的孤立波解及其色散关系。取近似于实际大气运动的物理参数作数值计算,得到了振荡型Ｒｏｓｂｙ孤立波的水平结构和移动特征,其结果较之寻常的Ｋｄｖ孤立波更接近于实际大气中的阻塞流型。     

关于控制迭代过程的结束条件

迭代法属于逐次逼近法,应用很广。它是求解函数方程、方程组和微分方程等的一种基本而重要的数值方法。在具体求解时,需要给出控制迭代过程结束的条件。现有的某些计算方法(或数值分析)的教材和书,在论述求解函数方程的计算方案、流程图(或框图)及算法语言程序时,常常将此条件取为相邻两次迭代值xk、xk-1的差小于给定的准确度本文指出这个条件是不完全的,讨论了该条件的正确表达式,由误差估计式给出了控制迭代过程结束条件的五种形式。     

地下水非稳定流的LTFAM算法

渗流域内应用拉普拉斯变换(LT)建立相应的有限分析(FAM)方程,顾及渗流域内地下水流的初始条件和边界条件,可在LT空间构成一个封闭的以水头像函数为变量的线性方程组。将此方程组所得的解,通过Stehfest数值反演公式,可归化为时间域的解(水头)。由于时间t被隐含在数值方程内,从而克服了传统数值法按时段(△t)逐步迭代的缺陷,提高了计算效率,也为用嵌入法建立地下水流管理模型提供了一条捷径。     

非球形轴对称粒子光散射的散射矩阵元素展开系数的数值计算

扼要地介绍了非球形粒子光散射的散射矩阵元素按广义球函数展开的基本理论,以及球形粒子散射矩阵元素间的关系。在此基础上较详细地阐述了计算展开系数的方法以及在程序研制中所遇到的一些问题。最后,对非球形的Ｃｈｅｂｙｓｈｅｖ粒子光散射的散射矩阵元素的展开系数进行了计算,结果表明数值技术和计算的正确性。     

非线性Kuamoto-Sivashinsky方程的精确控制

运用泛函分析性质以及Fourier变换的方法研究带有周期边界条件的非线性k-s方程在有限时间区间上的精确控制.首先研究线性化k-s方程的精确控制,证明对于任意给定的函数u0∈Hs,uT∈Hs,总能找到一个控制函数h使得线性化k-s方程有解u且满足u(x,0)=u0,u(x,T)=uT;然后结合线性化k-s方程的精确控制,通过定义Fredholm算子并应用Fredholm算子的一些理论找到非线性化k-s方程的控制函数,使其可精确控制.     

利用LS+AR模型和激发函数预报地球自转参数

分别采用LS+AR组合模型和包含大气角动量、海洋角动量的流体激发函数对地球自转参数进行长期预报。数值实验表明,激发函数预报精度优于LS+AR组合模型,其中大气角动量激发函数预报精度优于海洋角动量激发函数。     

沈阳地区地下水运动数学模型的定解条件及其函数式选择

用于求解地下水运动偏微分方程,只限于研究地下水变化的方程是不够的,还应具有说明地下水运动具体状态的初始值和边值这些附加的条件——地下水运动方程的定解条件。地下水运动方程定解条件的初值一般是从地下水观测中获得,而边值的确定则是在函数式的选择下进行的。根据确定一类边界的函数式,结合地下水的运动规律,总结沈阳地区十年期一类边值问题的构成,完成了一类边界处理,并确认为一稳定性状态,所测数值的十年期预测计算是一收敛过程。     

斜压大气中非线性ROSSBY波

本文利用位涡守恒方程,导出了斜压大气中非线性Rossby波满足KDV方程和MKDV方程,求得了斜压大气中非线性Rossby波足椭园余弦波和孤立波,并对它们的性质进行了讨论,着重用斜压Rossby立波的性质解释了大气中的一些重要天气现象如极涡、阻塞高压和切断低压。     

Thermohaline structure inhomogeneity associated with polynia at the northern margin of Emery Ice-shelf

Based on the hydrographic data in austral summer during the 22nd Antarctic Expedition of China(2005/2006),some features can be found about the northern margin of Emery ice shelf as follows.The heat content in the surface layer(0-50 m) at the eastern end and the western end of the ice-shelf margin is much higher than that at the middle.The upper mixing-layer depth and the seasonal thermocline depth at the middle of the ice-shelf northern margin are much shallower than those at the both ends.However there is much less difference between the middle and the ends in the bottom layer.The remote sensing photos show that the inhomogeneity in the surface-layer water is closely related to the spatial distribution of the floes and polynia in the area.     

Phylogenetic analysis of cultivable bacteria isolated from Arctic sea-ice

Phylogenetic analysis based on 16S rDNA of 8 strains of cultivable bacteria isolated from Arctic sea-ice was studied.The results showed that strain BJ1 belonged to genus Planococcus,which was a genus of low mole percent G C gram-positive bacteria;strain BJ6 belonged to genus Burkholderia of β-proteobacteria and the rest 6 strain all belonged to γ-proteobacteria,of which strain BJ8 was a species of Pseudoalteromonas,strain BJ2-BJ5 and BJ7 were members of genus Psychrobacter.Phylogenetic analysis also indicated that bacteria of genus Psychrobacter of the isolates formed a relatively independent phylogenetic cluster in comparison with other bacteria belonged to genus Psychrobacter.     

Information for authors

正1 Aims and Scope Advances in Polar Science(APS)is an international,peer-reviewed journal jointly sponsored by the Polar Research Institute of China and the Chinese Arctic and Antarctic Administration.APS is a comprchensive academic journal dedicated to presentation of multi-disciplinary achievements in Arctic and Antarctic expeditions and research.Its primary purpose is to publish achievements in fundamental research,applied     

Advances in Polar Science CONTENTS(Volume 25,2014)

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Guide to Authors： Journal of Mountain Science

<正>AIMS AND SCOPE(Editorial Policy)The Journal of Mountain Science(JMS)is devoted to mountains and their surrounding lowlands-ecoregions of particular global importance,with a particular emphasis on the important highlands/mountains in the world,such as the Tibetan Plateau,the Himalayas,the Alps,the Andes,the Rockies and many other mountain ranges of our planet.     

Journal of Mountain Science(JMS)

<正>The Journal of Mountain Science(JMS),founded in2004,is an international English-language journal on mountain sciences.JMS is supervised by the Chinese Academy of Sciences(CAS),sponsored by the Chengdu Institute of Mountain Hazards and Environment,CAS,published by Science Press China,and distributed by Springer exclusively throughout the world(excluding Mainland China).The JMS is published bimonthly,fulltexted in SpringerLink and CNKI,indexed/abstracted by     

Relationship of Arctic sea ice and Northern Hemispheric 500 hPa Polar vortices

Using the NCEP/NCAR reanalysis monthly 500 hPa height data on a 2.5 latitude-longitude grid and 1°×1° sea ice data,the polar vortex area,intensity index and arctic sea ice area index are calculated respectively,and the meridional distribution,period variation and the abrupts in the long range trend are analyzed to study their relationship.The results show that the meridional distribution of sea ice and polar vortex h-ave distinctive difference,the relative positions of them are different in the eastern and western hemispheres,and exept they have periods of 4 months,quasi half year,quasi year,4-5 years and 10 years commonly,and each of them has its own respective variation as well.The sea ice area is decreasing apparently since 1980's,so is the polar vortex area,but their abrupt changge time are different totally.The area of sea ice and polar vortex has prominent positive correlation,but the relationship of sea ice intensity,polar vortex intensity,polar vortex area is complicated.     

Author Index for Journal of Mountain Science Volume 11,2014,pp 1-1656

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Information for Authors

<正>The Journal of Ocean University of China(Oceanic and Coastal Sea Research)is a comprehensive academic quarterly sponsored by the Ocean University of China,published one volume per year.This journal is devoted to the publication of the theoretical and applied research