无心二次曲线位置的确定

无心二次曲线(即抛物线)位置的确定目前大多数教科书上和长期从事这方面研究的同志撰写的论文中都是通过探讨方程的系数来实现的，本文由文[1]中所给的方法，借助点到直线的离差给出了另一种确定无心二次曲线位置的方法。值得指出的是：这种方法可以直接确定抛物线的对称轴、顶点、开口方向，并且写出其标准方程和画出图形。     

抛物线的位置与作图

本文主要给出确定抛物线的位置并作出图形的简便方法(无需具体作坐标变换)。文中关于抛物线开口方向的判定方法,在常见的一些解析几何教材中都未曾提及,可供中学教师参考。1.确定位置先考虑如何确定抛物线的位置。我们的作法是:求出抛物线的对称轴和顶点的坐标,并确定抛物线开口的方向,而只需依据于方程的系数。设二元二次方程     

关于“二次曲线”教学的几个问题

一.二次曲线在中学数学中的地位和作用根据中学数学的总的要求,不难看出:直线和二次曲线是中学数学教学的重点。1、用代数的方法研究几何问题的优越性在“二次曲线”这一章得到了充分的体现。本章,通过对抛物线、椭圆、双曲线的标准方程的推导,就把研究二次曲线的几何问题,转化为研究二元二次方程的代数问题。用代数的方法研究曲线的性质,在处理一些几何问题上,有很多的优越性。同时通过二次曲线的教学,可以使学生对于直角坐标系中曲线和方程的相互关系得到较深刻的认识。2、二次曲线是学生获得必要的生产斗争实践知识的重要教材。在生产实践中,常常遇     

用配方法对二次曲线方程分类与化简

通过对二次曲线方程配方变形,对二次曲线方程进行分类,化简;然后根据直线与二次曲线相交时参数t的几何意义,确定二次曲线的标准方程.从而解决了利用坐标系的平移,旋转,不变量对二次曲线方程分类,化简时运算复杂或无法确定图形具体位置等问题.     

用配方法对二次曲线议程分类与化简

通过对二次曲线的标准方程进行分类,化简;然后根据直线与二次曲线相交时参数t的几何意义,确定二次曲线的标准方程.从而解决了利用坐标系的平移,旋转,不变量对二次曲线方程分类,化简时运算复杂或无法确定图形具体位置等问题.     

宏程序的研究与应用一加工斜椭圆

数控车床在加工二次曲线轮廓过程中。常用的指令G02／G03圆孤插补只能加工标准圆孤,对于二次曲线知椭圆、抛物线、双曲线奏的轮廓则难以完成。为此,必须采用宏程序编程。而斜椭圆的加工,必须通过旋转转换方程确定旋转椭圆的参数方程,才能编制出实际加工程序。试文以法兰克数控系统为例,详细介绍了宏程序在旋转椭圆车削中的应用。     

利用配方法讨论无心二次曲线

二次曲线为非中心曲线的充要条件及方程表示形式。本据此理论提出了利用配方法确定曲线的形状，大小和位置的方法步骤。     

化简二次曲线方程的一种简捷方法

二次曲线方程的化简与作图是解析几何的一个重要问题，也量一个已经得到解决的问题，用一般教科书上给出的坐标变换的化简方法，涉及到理论知识和公式较多，不便记忆，而且计算复杂，因此寻求化简二次曲线方程的比较简捷易行的办法，就成了近年来解几何学讨论较多的问题之一，本文将曲线的主直径用参数方程表示，根据参数的几何意义，求出半轴之长定出主直径的倾角（或斜率）就可以对二次曲线方程进行化简及确定图形的形状和位置。     

论二次曲线的不变量

<正> 二次曲线在直角坐标变换下的不变量,是解析几何里一个十分重要的问题。解析几何要求通过方程来研究图形的几何性质,反映图形的几何性质的量,是为方程的系数确定的,且方程的系数确定的几何性质的量如轴长,焦半径等则与直角坐标变换无关,这种和坐标轴的选择无关的性质,正是二次曲线最重要的性质。由二次曲线方程的系数所组成的     

二次曲线方程化简与作图的简易方法

针对二次曲线方程化简与作图的方法,有的化简简单,但难于作图;有的化简繁琐,但易于作图.寻找一种既易于化简又易于作图的简便方法是一个值得研究的问题.文章在深入探讨二次曲线方程化简并作图的四种方法:坐标变换法、主直径主方向法、不变量与半不变量法、因式分解法的基础上,通过分析,归纳这四种方法之间的联系,给出一种相对于前四种方法对化简二次曲线方程并作图更为简便的方法,得到两个主要结论.     

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.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with