度、半径约束最小生成树问题及其算法

提出了度、半径约束最小生成树问题,证明了该问题是NP-完全的.建立了该问题的数学规划模型.进一步给出了快速启发式求解算法,并分析了该算法的时间复杂性.分析和实例实验表明该算法具有良好的效果.     

文档碎片取证分析模型

为进行文档碎片取证调查,提出了一个文档碎片取证分析模型.该模型扩展了现有的文档碎片取证过程,并将不同抽象层次的文档碎片数据引入该模型.同时将扩展的可信计算技术应用于该模型,解决了文档碎片取证过程中证据链保全机制.对该模型的取证能力进行了评价.通过案例分析,该模型具有较强的文档碎片取证能力并能够进行分布式取证分析.     

保守修正BFGS算法及全局收敛性

基于新拟牛顿方程,提出一类保守修正BFGS算法.该算法的特点是:即使当目标函数是非凸函数时,该算法仍然是全局收敛的.在适当的条件下,该算法具有局部超线性收敛性.初步的数值实验表明,该算法是有效的.     

一类非线性动力系统的行为分析

文章对一类经典的非线性动力系统模型——三级电子管电路的VAN DER POL方程进行稳定性分析.首先,通过线性近似法对该微分方程在零点处的稳定性态做出判断,得出结论：该方程在零点处不稳定.再证明该模型存在唯一的极限环,最后用二变量多尺度法求出该方程的周期解.通过所求得的周期解,近似得出该模型的极限环.     

基于模糊关系传递闭包的聚类方法

根据数据之间的相似关系,构造了基于模糊相似关系传递闭包的聚类方法.该方法用数据之间的距离定义模糊相似关系,利用模糊关系的合成算子,构造该关系的传递闭包,该传递闭包是等价关系.以等价类为聚类.实验结果表明该聚类方法可得到与传统K-均值方法相同的聚类结果.     

求解一阶线性双曲型偏微分方程组的一个差分格式

利用有限差分法,构造一个求解一阶线性双曲型偏微分方程组的高精度隐式差分格式.该格式的相容性和收敛性被证明.进一步,Fourier级数法分析表明该格式无条件稳定.另外,该隐式差分格式可以转化为显格式求解,较同类格式的计算量小.通过实例验证,该格式数值结果绘制的图形稳定、光滑、效果良好.     

一种通信网络节点重要性的计算公式

针对基于节点的移除可能导致网络拓扑结构变化的不足,提出了一种确定通信网络节点重要性的评价公式.该公式综合考虑了节点在网络中的全局性影响,能精确地评价网络节点重要性,尤其对解决卫星网络的节点重要性评价方面.该计算公式定义了网络中节点重要性取决于该节点在网络中的位置信息和其他节点对该节点的贡献度.节点的位置由节点介数确定,其他节点对该节点的贡献度与其他节点的介数及紧密度相关.利用该公式对典型网络的节点重要性进行分析,并与其他评价方法进行对比,结果表明,该公式能精确并正确评价节点对网络的控制能力.     

使用除法算法对里德-所罗门编码进行解码

里德-所罗门编码是最广泛使用的纠错码之一.介绍一种使用除法算法的解码方法,发展该算法的理论并讨论支持该算法的例子.最后,证明与该解码算法有关的一个概率上的定理,关于何时该方法是最有效的,得出一些概率上的结果.     

广义双模实参数型相干纠缠态

构建一种广义双模实参数型相干纠缠态︱α,x;λ〉.该态不仅具有相干态的特性,而且具有纠缠态的特性.利用有序算符内的积分技术,证明该态具有完备性.利用该态的不对称积分构造一种具有压缩特性的压缩算符.而且利用该态还得到广义的P表示和广义的纠缠态.     

匿名通信系统时间攻击的时延规范化防御方法

为了防御针对匿名通信系统的时间攻击,提出一种基于数据包时延规范化的防御方法.该方法将数据流中所有时延间隔调整至一个固定值,防止攻击者嵌入标记信息,从而达到防御攻击的目的.该固定值利用经验指定法或者移动平均法确定.如果包间时延间隔小于该值,延长此包间时延间隔;如果包间时延间隔大于该值,则插入1个或者多个干扰包.这样可使得所有时延间隔相同且等于该固定值.对时间水印攻击的防御实验结果表明,该方法的防御效果不受攻击者选取的起始时间和用于嵌入水印的时间间隔影响.真实网络环境中的实验结果显示,时间水印攻击的错误识别率均值达到43.51%,证明了该方法的有效性.     

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