基于连续函数为自变量的Bernstein多项式的推广及其曲线曲面应用

用一般的连续函数h(x)替换经典Bernstein基的参变量x,对经典Bernstein多项式进行了推广.通过实例说明,这样得到的Bernstein多项式虽然不一定具有原Bernstein多项式的收敛性,但给出了推广的Bernstein多项式具有收敛性的条件.特别地,当h(x)是折线函数时,推广的Bernstein多项式也可能不具有可导性、保凸性、凸包等性质.而这种推广的Bernstein多项式的优势在于,可以通过调整折线函数的参数值,产生不同于经典形状的曲线和曲面,对自由曲线、曲面的设计具有一定的价值.     

Bernsteinα-多项式对单调函数的保持性质

研究了文献[1]中提出的一元Bernstein α-多项式，给出其关于函数单调性的保持性质，并构造出单纯形上二元Bernstein α-多项式，也给出类似于一元的结果．     

关于Bernstein算子的一些性质

§1 引言Bernstein算子B_n:C[0,1]→C[0,1],其定义为:其中. 设{k_n}是自然序列,本文讨论的是Bernstein多项式B_n(f;x)导函数的性质、多项式     

三角域上的二元Bernstein多项式

证明了三角域上的二元Bernstein多项式的两个新的性质。     

基于Bernstein多项式构造前向神经网络的遗传算法

首先,介绍一元Bernstein多项式的逼近定理和基本性质,并引入二元甚至n元Bernstein多项式,从而根据一元Bernstein多项式在相邻等距剖分点的差值为后置连接权构造一个三层前向神经网络;其次,通过编码机制、模拟选择、遗传复制、交叉和变异等操作给出算法运行过程;最后,利用误差函数和适用度函数对前置连接权及阈...     

一类推广的Bernstein算子的逼近

通过Bernstein多项式的基函数,引进一类推广的Bernstein算子序列,并借助于连续模研究该算子序列的一些逼近性质.同时,还得到一个Voronovskaja-type结果.     

多元Bernstein多项式分片光滑条件

本文根据多元Bernstein多项式的性质,导出了S元多项式在S-1维超“平面”上光滑连接的必要和充分条件。     

单纯形上修正Bernstein算子的逼近性质

对高维单纯形上的Bernstein多项式进行了变形，通过减少多项式的项数以获得更好的计算效果，从而得到了两个修正Bernstein算子的模型，并且定义了新的函数类．文中利用函数构造法、不等式的缩放和单纯形上Bernstein算子的性质，研究了修正算子在一定条件下的收敛性和保证收敛的最小项数，同时给出了算子不收敛的范围．     

单纯形上Bernstein多项式的渐近展开式及关于阶的高阶差分(英文)

给出了单纯形上两个相邻Bernstein多项式的差的一个估计式以及Bernstein多项式的一个渐近展开式并讨论了Bernstein多项式关于阶的高阶差分,得到一个极限公式。     

L_p范数下随机连续函数空间中的Weierstrass定理

通过概率方法对随机连续函数的多项式逼近性质进行了研究.借助随机Bernstein算子给出了Lp范数下随机系数多项式逼近的定性估计,进而推广了Weierstrass定理.     

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.     

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