解二阶抛物型方程的一族高精度恒稳格式

对二阶抛物型方程构造了一族含参数高精度三层差分格式.当参数满足一定的条件时,差分格式绝对稳定,其局部截断误差阶数最高可达O(τ2+h4).适当地调节参数,可以得到一个七点显式差分格式和一个两层六点隐格式.数值例子表明,对稳定性所作的分析是正确的.     

二维Helmholtz方程的改进六阶紧致差分法

为得到求解二维Helmholtz方程的高精度差分法, 构造了一种改进六阶紧致差分格式: 首先, 给出一种带优化参数的六阶紧致差分格式的截断误差; 然后, 对此截断误差的部分项进行二阶紧致逼近, 得到一种改进紧致差分格式; 其次, 对该格式进行了收敛性分析, 证明其为六阶收敛的; 最后, 基于极小化数值频散的思想, 给出该格式优化参数的加细选取策略。与带优化参数的六阶紧致差分格式相比, 数值实验说明改进六阶紧致差分格式的数值精度有了显著提高, 且其误差对波数k的依赖性更低。     

一维Helmholtz方程的四阶优化紧致差分法

构造了一维Helmholtz方程的四阶优化紧致差分格式.首先,建立了带参数的四阶差分格式,并通过经典的频散分析得到差分格式的频散方程,给出该格式的数值波数与真实波数之间的误差.其次,基于极小化数值频散的思想,提出了差分系数的整体选取策略和加细选取策略.最后,数值结果表明本文所提出的带加细参数的四阶差分格式抑制了数值频散,有效地提高了数值计算的精度.     

一种构造三维双曲型方程完全守恒差分格式的方法

研究三维双曲型方程组的完全守恒差分格式,在差分格式中引入参数的方法,针对三维欧拉双曲型方程进行讨论,通过一系列变换和运算技巧,得到三维双曲型方程组的完全守恒差分格式,理论上证明了这些完全守恒差分格式具有二阶精度,并对三维非定常无粘性,无热传导和可压缩的欧拉流体力学方程组建立含待定参量的差分格式,为它的数值求解提供了一种方便可行的差分格式。     

解变系数抛物型方程组的一族显式差分格式

本文对一维抛物型方程组构造了一种带多参数的三层显式差分格式，证明只要选择适当的参数和在适当的范数下，可使差分格式稳定．     

具波动算子非线性Schrödinger方程线性化差分格式

构造了具波动算子的非线性Schr?dinger方程的一种线性化差分格式。即在守恒非线性差分格式的基础上,利用Taylor方法展开非线性项,引入小参数得到该方程的线性化差分格式。利用Fourier方法证明了其格式的收敛性和稳定性。最后通过数值例子验证了该方法的可信性和有效性。     

解四阶杆振动方程的三层高精度差分格式

对四阶杆振动方程构造含参数高精度三层差分格式,当参数满足一定条件时,差分格式稳定,局部截断误差阶数最高可达O(τ4+h8).数值例子说明该方法对稳定性的分析是正确的.     

奇摄动抛物型方程的一致收敛差分格式

讨论两类奇摄动抛物型方程,构造相应的拟合网格差分格式,并证明差分格式关于小参数是一致收敛,数值例子显示数值解很好地逼近精确解．     

含两参数的抛物型方程混合问题的差分解法

研究含２个小参数的抛物型方程的奇异摄动问题,构造了指数拟合差分格式并证明了差分格式的解一阶一致收敛于微分方程的解,提高了一致收敛的精度．     

解四阶抛物型方程的高精度差分格式

对四阶抛物型方程构造了一族含参数高精度三层差分格式 .当参数满足一定的条件时 ,差分格式稳定 ,局部截断误差阶数最高可达 O(τ2 h6) .最后 ,用数值例子说明对稳定性所作的分析是正确的 .     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that