基于新指数基函数的有理二次三角Bézier曲线（英文）

通过在三角基函数中引入两个指数函数,构造了一种具有4个形状参数的有理二次三角Bézier曲线,它与有理二次Bézier曲线有着相类似的性质.给定控制顶点,该曲线可通过改变形状参数和权因子而调整形状.适当选取控制顶点、形状参数和权因子时,一些二次曲线可以被精确地表示.讨论了连接两条曲线所满足C~0,C~1和C~2的连续条件,并给出了一些例子.     

NURBS曲面权因子及其应用研究

对非均匀有理B样条(NURBS)的权因子作了分析研究。首先，阐述了NURBS曲面权因子的几何意义，说明了权因子是有关4点的交比，并分析了权因子的极限性质以及零权因子对曲面形状的影响；其次，就曲面上一点在控制顶点方向与任意方向移动这两种情况，给出了曲面形状调整时权因子的计算公式；最后，给出了曲面权因子调整的应用算例。     

有理Bzier曲线的光顺拟合法

研究了用有理Ｂéｚｉｅｒ曲线光顺拟合一组平面点列的问题．首先用三次Ｂéｚｉｅｒ曲线拟合平面数据点列,求得拟合Ｂéｚｉｅｒ曲线的控制顶点,然后在能量积分最小的条件下,通过最优化计算调整权因子,使所得到的曲线光顺     

基于新指数基函数的有理二次三角Bézier曲线

通过在三角基函数中引入两个指数函数,构造了一种具有四个形状参数的有理二次三角Bézier曲线,它与有理二次Bézier曲线有着相类似的性质.给定控制顶点,该曲线可通过改变形状参数和权因子而调整形状.适当选取控制顶点、形状参数和权因子时,一些二次曲线可以被精确的表示.讨论了连接两条曲线所满足C⁰,C¹和C²的连续条件,并给出了一些例子.     

带两个形状参数有理二次三角Bézier曲线

本文提出了带两个形状参数的有理二次三角Bézier曲线,由4个控制顶点生成的曲线具有传统有理三次Bézier曲线的几何特性,包括端点性质、对称性、凸包性、几何和仿射不变性、变差缩减性.分析了在权因子固定情形下,通过改变形状参数值可以局部调控曲线形状;也得出当形状参数值都为-1时,曲线可退化为直线段.曲线在适当的控制顶点下,可精确表示椭圆弧和圆弧,从而可方便整圆的表示.在控制顶点和权因子相同的条件下,当形状参数取值在一定范围内,曲线具有比有理三次Bézier曲线对控制多边形更好的逼近.     

修改NURBS曲线形状的一种方法

NURBS曲线是计算机辅助几何设计和计算机图形中最常用的参数曲线。采用NURBS曲线的齐次坐标表示，给出了通过控制顶点和权因子同时改变来修改NURBS曲线形状的一种方法。     

有理Bézier曲线的几何约束修改

有理 Bézier曲线是 CAGD和计算机图形学中常用的参数曲线。研究了有理 Bézier曲线的几何约束修改。给出了基于控制顶点和基于权因子的约束优化方法 ,并给出了数值例子     

一种二次有理Bézier曲线延拓的有效算法

给出了一种平面二次有理Bézier曲线光顺延拓的有效算法.该法首先利用拼接条件初步确定了延拓曲线的控制顶点,然后以延拓曲线的应变能作为光顺准则,通过极小化应变能,最终求得延拓曲线的权因子及控制顶点,从而获得与原曲线C1拼接的光顺延拓曲线.实例表明,该算法使用效果较好.     

基于NURBS技术的船体几何重构研究与实现

为实现船体的几何重构,基于非均匀有理B样条(NURBS)技术针对DTMB5415船体几何重构展开研究.根据NURBS技术原理以及边界处理过程,求解过程结合非节点边界条件,采用一种无需型线切矢量的曲线控制顶点反算算法.利用C++语言编写的程序实现船体型线和船体曲面重构,分析了控制顶点和权因子特性对几何重构结果的影响,通过...     

平面NURBS曲线的自动光顺算法

目的 给出平面NURBS曲线的自动光顺算法。方法 基于节点消去、插入和重新确定权因子等基本算法，根据给定的光顺准则，自动选择需要光顺的节点，局部修改控制顶点和权因子。结果 建立保凸节点消去算法，实现了平面NURBS曲线的自动光顺。结论在给定误差范围内．该算法既可保证节点结构不变，也可对曲线进行微调，达到光顺目的。     

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.     

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