基于高速PCB的信号完整性理论分析

介绍了高速PCB设计中的信号完整性概念以及影响信号完整性的因素和不完整性形成原因;从传输线理论的层面上重点分析了高速电路设计中反射和串扰的形成机制并提出了解决办法;基于IBIS模型实现了对ARM9 S3C2410X01芯片的时钟输出引脚的仿真,给出了IBIS模型仿真步骤.     

高速电路板的信号完整性设计与仿真

提出了一种高速电路板信号完整性设计与仿真分析方法.介绍了信号完整性基本理论以及基于仿真软件Hyperlynx的信号完整性仿真流程,重点讨论了如何采用高速PCB设计方法保证高速数采模块的信号完整性,并对在此方法下所设计电路板的关键网络进行了IBIS模型仿真.仿真结果表明:采用该方法能有效实现数据采集模块信号完整性的设计及仿真.     

一种高频时钟源的设计与实现

目的　研究一种用于高速数据采集的高频时钟源的设计与实现。方法　在其物理实现中采用微带传输线的连接方式及多种抗干扰设计,进行了基于输入/输出缓冲参数特性(IBIS)模型的信号完整性分析及软件仿真。结果　给出了示波器实测的高频时钟源输出结果。该时钟源可输出500MHz或外接信号源频率的两路正交差分ECL时钟信号。结论　系统工作稳定可靠,能够满足各项性能指标要求。     

高速数字电路中信号完整性及仿真策略

在高速数字电路中，信号完整性问题至关重要。介绍了高速数字电路中的信号完整性，并给出了信号完整性仿真分析策略。     

基于IBIS模型的高速数字I／O缓冲器的瞬态行为建模

引入了一种基于最新版本的IBIS模型给出的信息构造高速数字I／O缓冲器的瞬态行为模型的方法，阐述了从IBIS建模数据中得到这种瞬时状态转换行为模型的过程，同时获得了建模所需要的充分条件，与相应的晶体管级模型相比，该方法在获得了更高仿真精度的同时，提高了具有大量同步开关器件芯片互连的仿真速度，最后，为了验证模型的有效性，给出了该模型和晶体管级模型（SPICE模型）模拟结果的比较。     

高速互连信号串扰的分析及优化

高速数字设计领域里,信号完整性已经成了一个关键的问题,给设计工程师带来越来越严峻的考验。信号完整性问题主要为反射、串扰、延迟、振铃和同步开关噪声等。本文基于高速电路设计的信号完整性基本理论,通过近端和远端串扰这种方法来研究多线间串扰问题。利用Hyperlyynx,主要分析串扰对高速信号传输模型的侵害作用并根据仿真结果,获得了最佳的解决办法,优化设计目标。     

高速互连设计中串扰噪声的抑制策略研究

在高速互连设计中,信号完整性问题越来越突出,愈来愈严重的信号噪声已经成为不可避免的问题。分析了串扰仿真模型的优化方法,重点研究了耦合长度与饱和长度比例对近端串扰的影响、开关信号上升时间对远端串扰的影响和紧耦合微带线串扰模型的端接控制。运用信号完整性分析软件Hyperlynx建立仿真模型,对影响串扰的各种因素进行仿真分析,并总结其抑制和改善的方法,最后提出高速互连设计中减小串扰噪声的策略。     

基于高速PCB传输线建模的仿真

在高速印刷电路板(PCB)设计中,逻辑门元器件速度的提高,使得PCB传输线效应成了电路正常工作的制约因素.对传输线做计算机仿真,可以找出影响信号传输性能的各种因素,优化信号的传输特性.采用全电荷格林函数法结合矩量法提取高速PCB传输线分布参数并建立等效时域网络模型,应用端接I/O缓冲器IBIS瞬态行为模型,对实际PCB布线进行电气特性仿真,其结果与Cadence公司的SPECCTRAQUEST软件仿真结果一致,且仿真效率得到提高.     

高速数字电路的信号完整性分析及仿真

在高速数字电路设计中,信号完整性是设计中至关重要的问题.本文介绍了信号完整性分析的相关基础理论,运用HyperLynx信号完整性仿真软件,对串扰和反射问题进行了分析,并给出相应的修改策略,尽量减小信号完整性产生的问题.     

基于最优小波包基改善高速长输信号的完整性

为了解决理想无损传输线理论在分析高速信号长距离输送时的不适用性的问题,将信号衰减因子引入高速长输信号的反射和串扰分析。围绕由不确定环境骚扰、反射和串扰噪声所引出的高频数字信号的完整性问题,通过对将自底向顶和深度优先相结合的最优小波包基搜索策略的探讨,采用数字仿真与实验数据相结合的方法,提出基于最优小波包基改善高速长输信号完整性的方法。数字仿真结果表明：最优小波包基方法消噪效果优于小波方法或普通小波包方法,可提高高频数字信号的边沿质量,有利于高速长输信号完整性的改善。     

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