加权BA网络负荷重分配建模及级联抗毁性

增强复杂网络在级联故障下的抗毁性具有重要的实际应用意义。在考虑了网络中边之间的差异性,基于BA无标度网络模型构建了加权BA无标度网络模型,对负荷重分配策略进行建模,分析了分配过程中局部规模大小对网络抗毁性的影响,确定出了最佳负荷重分配策略,并研究了蓄意攻击条件下采取不同负荷重分配策略时重要网络参数对网络抗毁性的影响。仿真结果表明,局部规模越小、权重系数越小、平均度越大,网络的抗毁性越强,且采用就近局部负荷重分配策略时网络抗毁性始终高于采用就近全局负荷重分配策略时网络的抗毁性。研究结果可为提高复杂系统的级联抗毁性提供理论参考。     

基于级联失效的复杂网络抗毁性

传统的复杂网络抗毁性研究主要基于网络静态连通性,而忽视了网络动态特征。该文在网络动态性基础上,研究级联失效条件下复杂网络的抗毁性能,对ER随机网络模型、BA无标度网络模型和PFP互联网拓扑模型这三种模型在不同攻击策略下的抗毁性进行了对比分析和仿真实验。实验结果表明：在随机攻击下,ER网络表现最为脆弱,而BA网络的抗毁性...     

基于动态信息的级联失效负载重分配策略

为解决级联失效网络负载重分配问题,提出了一种将网络局部信息和动态信息相结合的负载动态重分配策略.该策略根据节点的度与节点实时处理能力计算节点权重,并以此依次进行负载重分配;同时,按一定比例选取失效节点暂停工作,其负载重新分配进程相应停止.在BA无标度网络、WS小世界网络和ER随机网络上的仿真结果表明,在一定的参数条件下,相对于介数分配策略与度数分配策略,动态重分配策略通过降低网络整体负载率、优化网络实时流分布缓解级联失效的效果更为明显.     

面向级联失效的复杂层次网络可靠性

为深入研究现代军事复杂网络在级联失效下的可靠性,基于复杂网络的小世界效应、无标度特性和层次模块性,通过网络模块复制迭代方式,构建复杂层次网络模型;在不完全信息条件下,提出一种失效节点负荷局部再分配模型,利用网络连通熵作为网络连通性指标,建立复杂层次网络级联失效模型.研究结果表明:存在一个容限系数的最小阈值,当网络中的容限系数大于该阈值时,任意一个底层叶节点失效均不会导致网络发生级联失效,同时可以通过增加网络模块内部连接程度的方式提高网络可靠性.     

城市复杂地铁网络级联失效抗毁性分析

为全面分析了解地铁网络抗毁性问题,保障地铁网络安全平稳运行。采用复杂网络级联失效理论对城市地铁网络抗毁性进行研究。以北京地铁网络为例,构建北京地铁网络级联失效模型,通过MATLAB软件实现级联失效模型的仿真运算,对比分析不同节点攻击策略北京地铁网络抗毁性。仿真结果表明:随机攻击策略对地铁网络破坏性相对较小,而面临节点重要度和介数的两种蓄意攻击策略时,地铁网络抗毁性较弱。并进一步为地铁网络建设以及运营管理提供理论支持。     

复杂网络子图中心性分析

许多现实网络虽然具有小世界和无标度的全局结构特征,但可能具有非常不同的局部结构特征,子图从局部层次刻画了网络内部相互连接的特定模式.本文通过仿真分析的方法研究了ER随机网络、WS小世界网络和BA无标度网络模型的子图中心性的特点,得出了这三类网络模型的子图中心性与网络密度、重连概率和网络规模之间的关系.仿真结果表明,子图中心性能够刻画复杂网络的拓扑结构.     

基于节点重要度动态评估的复杂网络级联失效分析

级联失效前的评估和检测是预防和控制级联失效现象的关键,对充分把握整个网络系统的稳定运行至关重要。为深入探究级联失效传播过程的内在机理,提出一种考虑网络动态特性的节点重要度评估模型;在此基础上,采用一种更符合真实复杂系统的非线性容量负载模型,利用该模型进行不同攻击策略下的级联失效仿真,以网络的最大连通子图比例为测度量化网络抵御级联失效的抗毁性,仿真结果表明,节点41所在的广安市与节点55所在的重庆市,无论是在静态节点重要度评估,还是动态节点重要度评估下,均是成渝铁路网络中最关键的节点;此外,不考虑级联失效情况下,在网络的静态拓扑结构中,节点的度中心性更能代表节点的关键程度;而在动态的网络拓扑结构中,节点的介数中心性更能代表节点的重要性,与度值攻击相比,采用重要度攻击策略能以更快的速度击溃网络;考虑级联失效情况下,与其他攻击策略比较,采用重要度攻击策略时,在级联失效的作用下,仅攻击2个节点,网络便会迅速崩溃,验证了节点重要度动态评估模型的有效性;同时探讨了网络在不同模型参数下抵御级联失效的抗毁性,实验结果表明,在一定范围内提高负载系数、容量系数可以有效提高网络抵制级联失效的抗毁性;受网络拓扑结构和攻击策略的影响,需设置较大的节点容量,来预防网络的级联失效。     

不同信息条件下加权复杂网络抗毁性仿真研究

针对加权复杂网络的抗毁性分析问题,选取网络效率和网络鲁棒性作为抗毁性的度量指标,对加权网络在不同信息条件下抗毁性的变化进行数值仿真模拟.最后,对成本和性能约束下加权网络的抗毁性进行定量分析,给出不同信息条件下加权网络抗毁性的优化策略.结果表明:在基于局部拓扑信息的攻击策略下,权重系数越大,网络的抗毁性越强;在基于全局拓扑信息的攻击策略下,网络的抗毁性要优于基于局部信息的攻击策略,且权重系数为0.5的网络在攻击初始阶段抗毁性最强;另外,若能在攻击早期加大对节点的防护力度,则会大大降低对网络性能的影响.     

基于搜索效率的复杂网络多模型并行演化分析

很多真实的复杂网络呈现无标度性．但是,这些网络为什么在增长过程中遵从优先连接规则？现有研究尚未给出有力的解释．一个合理的猜想是：这些网络如果不遵从优先连接规则,则将处于不利的地位．为证实这一猜想,采用搜索效率作为评价指标,量化评价不同演化模型的优劣．首先提出一种新的复杂网络并行演化模式,使得同一网络中不同的局部遵从不同的演化模型,从而在统一的基础上比较不同演化模型搜索效率的优劣．以BA无标度网络、WS小世界网络和随机网络为基础,构建了异质复杂网络．其次,采用随机游走搜索策略和DS最大度搜索策略,比较遵从不同演化模型的异质子网的搜索效率,力图解释复杂网络中演化模式同质化的原因．实验发现一种“信息壁垒”现象,即处于劣势的网络模型,其所属节点很难被其他模型的节点访问到．实验结果表明：对于以搜索为重要功能的复杂网络,无标度网络具有最强的适应性,从而在一定程度上解释了无标度现象在众多现实复杂网络中存在的原因．     

BA无标度通信网络的级联故障研究

研究了通信网络在不同通信负载下的鲁棒性问题.采用BA无标度网络作为通信网络模型,采用大度节点优先的局域结构路由策略,研究了网络在自由畅通态的级联故障.仿真研究表明:网络的鲁棒性、平均效率随网络中信息产生速率的增加而减小;当网络处于临界拥塞态时,攻击网络中10％的节点,网络中会有约50％的节点由于级联而失效,攻击网络中20％的节点就会使网络的效率变为零;当网络中节点负荷较轻时,攻击网络中40％～50％的最大度节点也可使得整个网络崩溃.     

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