傅立叶变换在工程应用中的演变

傅立叶变换是分析信号与系统最基本的分析工具,但在工程实际应用中具有很大的局限性,由此产生了多种傅立叶变换的演变形式,常见的包含离散傅立叶变换、快速傅立叶变换、短时傅立叶变换、小波变换、Laplace变换、Z变换等,这些变换形式都与傅立叶变换有关,都可以从傅立叶变换推广得到,它们和傅立叶变换之间以及它们相互之间可以转化.     

Hilbert变换及其基本性质分析

Hilbert变换是广泛应用于数字系统和通信系统的基本重要变换.对Hilbert变换及其性质做了较为详细的介绍,给出常用信号的Hilbert变换形式,研究部分特殊函数的变换形式,并与傅立叶变换,Z变换,拉普拉斯变换做比较.     

直射变换的透视定义

给出透视变换定义,研究了透视变换与透视对应的关系,利用直射变换可分解为透视变换,得出直射变换的充要条件,进而给出直射变换的透视定义.     

Laplace变换与某些积分变换的关系结果

证明Laplace变换与Stieltjes变换间关系定理，并由此得到关于Laplace变换，Stieljes变换，广义Stieltjes变换，Laguerre变换间关系的许多结果，同时给出其对积分方程的应用。     

纽结的(m,n)-变换

定义了一类新的纽结变换——(m,n)-变换.区别于交叉点变换和#-变换,(m,n)-变换把m条线从n条线的下方移到了上方.对于新定义的纽结变换,证明了对任意的正整数m、n,(m,n)-变换都是可使纽结变成平凡结的变换.通过对纽结投影图的讨论,先证明(1,2)-变换和(2,1)-变换都是可平凡化变换,然后再通过数学归纳法证明了该结论.结果表明,(m,n)-变换也可以像交叉点变换和#-变换一样用来定义纽结的不变量.     

基于变换函数的风险度量方法之比较

在变换函数的基础上对包括VaR、TVaR以及基于PH变换、DP变换、Beta变换、Beta变换和王变换六种风险度量方法进行比较研究.通过比较它们的变换函数和生存函数,讨论了它们各自的性质和特点.     

小波变换与Fourier变换的关系

从对Fourier变换的分析揭示出小波变换是数学本身发展的必然;从Fourier分析的局限性,讨论小波变换的变焦距特性;从Fourier变换的固定基给出小波变换基的选取原则,从而得出小波变换是Fourier变换的继承和发展。     

勒贝格积分与积分变换公式

目的为了减弱面积变换公式和二重积分变换公式成立的条件。方法利用勒贝格积分和傅立叶级数讨论平面区域面积变换公式和二重积分变量变换公式。结果在比现有文献有关结论中较弱条件下得到了面积变换公式和二重积分的变量变换公式。结论对现有的有关面积变换公式和二重积分变量变换公式的结果作了相应的改进和推广。     

S变换在地震时频分析中的对比研究

介绍了S变换基本原理的基础上,通过设计实验数据,对比Fourier变换、短时窗傅立叶变换和S变换的时频分析特点,最后对地震数据分别应用S变换和Gabor变换,认为S变换具有自身独特的优点,更适合于地震资料的时频分析。     

有关幂等变换的相关结论

无论是从理论上还是从应用上来看,幂等变换是重要的线性变换.有关幂等变换的结论常见于各种教材和习题中,尤其在研究生入学考试试题中.文章给出了四个幂等变换的相关结论:幂等变换与线性变换的像和核、与射影变换,幂等变换与可逆线性变换,以及幂等变换的应用一利用幂等变换证明幂等变换.     

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.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

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-