参数扰动下时滞忆阻神经网络的Lagrange稳定性

根据忆阻器物理特性,建立了一类荷控忆阻神经网络模型,模型中忆阻器的记忆特性被保留.针对实际忆阻器阻值与理想模型存在差异造成忆阻神经网络中参数不确定的问题,研究参数扰动下时滞忆阻神经网络的Lagrange稳定性.将模型重构为双重扰动形式以处理忆阻器忆阻值变化造成的模型中的参数变化.通过构造Lyapunov函数和应用线性矩...     

基于Simulink的忆阻器模型

为了使忆阻器具有与其他器件相结合的能力,本文在惠普实验室提出的忆阻器物理模型电路关系的基础上,在Simulink中用二种方法对忆阻器进行了双端口建模,方便准确的实现了对于忆阻器的仿真。与编写M文件、构建图形用户界面和搭建输入输出模型的建模方法相比,基于Simulink的双端口模型不仅能够方便准确的观察忆阻器的输入输出特性,而且具有更广阔的应用范围,对于忆阻器的研究有一定的指导作用。     

含两个忆阻器的隐藏吸引子及其Hamilton能量控制

以Kirchhoff定律为理论基础,设计含磁控、荷控两种忆阻器的非线性电路模型。分析系统的平衡点特性时,发现此忆阻系统存在隐藏吸引子,通过仿真关于参数的分岔图、相轨迹、Poincaré映射图,发现其具有丰富的动力学特性,比如,存在混沌、超混沌、暂态混沌、周期等非线性现象。根据Helmholtz定理计算得出此忆阻系统的Hamilton能量函数,讨论了系统的电容在充放电过程中电流随时间变化时与产生的能量变化关系并提出新的Hamilton能量控制法,通过选择不同的控制参数将忆阻系统的控制到期望的状态。     

驱动忆阻性负载逆变系统中Hopf分岔控制的研究

针对驱动忆阻性负载逆变系统易发生Hopf分岔、导致系统出现振荡频率大于工频频率但远小于开关频率的不稳定现象，提出交流输出电压微分反馈控制方法，实现了对系统中Hopf分岔行为的有效控制。驱动忆阻性负载逆变系统因Hopf分岔引起的振荡现象属于慢尺度不稳定行为，因此建立了交流输出电压微分反馈控制下系统的平均模型，基于谐波平衡法求得系统变量的周期解，以Floquet理论揭示了系统中出现慢尺度不稳定行为的机理，给出了确保系统稳定运行的控制参数取值范围。此外，通过计算Floquet乘数对积分参数的敏感值，分析了交流输出电压微分反馈控制下系统在积分参数受到扰动时的抗干扰能力。研究结果表明：交流输出电压微分反馈控制方法可有效控制驱动忆阻性负载逆变系统中的Hopf分岔行为，能大幅度增加确保系统稳定的控制参数取值范围，并可增强系统的抗干扰能力。最后，通过PSpice仿真结果和电路实验结果的一致性，验证了理论分析的正确性和所提出的控制方法的有效性。     

忆阻混沌系统的同步

忆阻器之所以引起了人们的大量关注,是因为它具有其一些特殊的特点,在普通的混沌系统中代替蔡氏二极管通过用忆阻器,因之得到了一个忆阻混沌系统;研究了忆阻混沌系统的同步,通过用Lyapunov稳定性理论,并设计一个脉冲控制器来实现忆阻混沌系统在不同的条件下的同步,从理论分析上说明了结果的有效性。     

基于忆阻器的鉴相电路设计与分析

分析忆阻器的基本理论,推导忆阻器阻值与电量、时间的函数关系,使用Simulink建立忆阻器模型,并验证该模型在正弦信号激励下,电流和电压具有滞回特性.设计基于忆阻器的鉴相电路,将相位差测量转化成对脉冲宽度的测量,对方法进行理论分析,并通过仿真实验验证了电路的功能.通过仿真、计算,得到忆阻器在边界非线性效应的影响下,非线性误差为9.82%.     

多种连接模型的忆阻神经网络学习

忆阻器以其独特的非易失性、天然的记忆功能以及纳米级尺寸,在人工神经网络、信号处理和模式识别等方面展现了巨大的应用前景。采用了基于STDP学习规则的忆阻神经网络,运用了网络自适应突变以及网络拓扑结构变化的基因算法,其中包括隐藏层神经元个数,连接权重以及神经网络突触模型的变化。比较了基于HP线性忆阻器模型,非线性忆阻器模型以及阈值模型这3种不同忆阻器模型的忆阻神经网络,并提出了学习效果更好的混合型忆阻神经网络。     

忆阻神经网络图像处理综述

忆阻神经网络能有效改善传统神经网络电路复杂、不易集成以及能耗大等不足。概述了忆阻器与忆阻神经网络,以及目前忆阻神经网络在图像处理方面的应用。基于忆阻特性,实现神经网络突触的动态可变,使忆阻神经网络比传统神经网络在图像处理领域具备更多优势且应用范围更广。同时,展望了忆阻神经网络未来发展前景。     

一种基于有源忆阻器模型的混沌电路

提出一种内部状态变量导数中含有平方项的有源忆阻器模型;并基于该模型构造了一个仅含电容、电感和忆阻器三个元件的混沌电路系统。该系统仅包含有一个平衡点;且吸引子关于原点中心对称。通过系统的李雅普诺夫指数谱和分岔图发现,在不同的电阻参数下该系统会以混沌危机和倒分岔两种方式退出混沌。最后,利用运算放大器等对该忆阻器进行电路模拟,给出了混沌系统的电路实现。     

基于改进忆阻器的混沌电路研究

忆阻器是一种具有记忆和连续输出特点的非线性电阻器,针对窗函数忆阻器模型的不足,提出了一种改进的窗函数,它通过添加一个参数来关联忆阻器的线性与非线性特性。为了对该窗函数进行验证,运用了数值分析与模拟电路分析的方法,仿真得出了忆阻器的伏安特性曲线,结果表明,使用改进窗函数的忆阻器模型更加接近实际物理状态。同时,为了进一步研究该模型的电路特性,将该模型应用于蔡氏混沌电路,通过MATLAB仿真得出其相图,并分析它的李雅普诺夫指数谱,数据表明该电路能产生混沌现象,因此,该忆阻器模型是一个能被应用的非线性模型。     

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