学员视角下一道第二类平面曲线积分题目的解法探讨

为培养学员的发散思维,针对一道第二类平面曲线积分题目的计算方法进行探讨,提出4种计算方法:可以利用格林公式计算;可以先将曲线方程代入被积函数中,再利用平面曲线积分与路径无关的性质计算;也可以先利用平面曲线积分的性质,再利用平面曲线积分与路径无关的性质计算;还可以将其直接转化成定积分计算。     

对称性在两类曲线积分中的应用

利用积分区域的对称性和被积函数的奇偶性可以简化曲线积分的计算.文章给出平面曲线积分和空间曲线积分的对称性定理,最后总结对称性在两类曲线积分中的应用.     

平面第二类曲线积分的一种简便计算方法

第二类曲线积分的计算在微积分学中是一个难点,其中概念既多又抽象,计算既繁又难以判断;而在研究生入学考试的命题中,曲线积分的出题率却又非常高,同时又伴随着题目难度大、解题正确率低的现象。但是,若将格林公式进行转化,就可得到平面第二类曲线积分计算的一种简便方法。它无需更多的判别就可直接进行计算,给正确理解、准确计算平面第二类曲线积分提供了一种思路。     

无穷曲线上的第二类曲线积分

在有限长曲线段上的第二类曲线积分定义的基础上,对第二类曲线积分做了进一步推广,给出了曲线长度为无穷长情形的第二类曲线积分定义与相关性质及其收敛性判定法,最后举例对无穷曲线上的第二类曲线积分进行了计算。     

无穷曲线上的第二类曲线积分

在有限长曲线段上的第二类曲线积分定义的基础上,对第二类曲线积分做了进一步推广,给出了曲线长度为无穷长情形的第二类曲线积分定义与相关性质及其收敛性判定法,最后举例对无穷曲线上的第二类曲线积分进行了计算.     

两类含参变量Dirichlet积分的公式解

给出了含参变量Dirichiet积分In,M(s)的定义。数学分析中的许多含参变量积分都是In,m(s)的特例。利用三角降次公式及解析函数的理论解决了含参变量Dirichiet积分的公式解问题,由此推出第一类Dirichlet积分与第二类Dirichlet积分的公式解。通过计算,解决了In,m(s)的表示问题。     

第二类广义曲线积分

在积分曲线为可求长的第二类曲线积分的基础上,利用一元函数广义积分的思想,给出了第二类广义曲线积分的定义、相关性质和第二类广义曲线积分的收敛性判定,并对部分性质和定理进行了推理论证.     

Green公式及其证明

首先指出数学分析中反映二重积分和第二类平面线积分联系的Green公式可以看成是散度定理的一种特殊情形，然后利用散度定理给出广义分部积分公式、第一Green公式和第二Green公式的证明．     

第二类广义曲线积分

在积分曲线为可求长的第二类曲线积分的基础上，利用一元函数广义积分的思想，给出了第二类广义曲线积分的定义、相关性质和第二类广义曲线积分的收敛性判定，并对部分性质和定理进行了推理论证．     

Green公式及其证明

首先指出数学分析中反映二重积分和第二类平面线积分联系的Green公式可以看成是散度定理的一种特殊情形，然后利用散度定理给出广义分部积分公式、第一Green公式和第二Green公式的证明．     

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