现场总线技术及其应用研究

对于现场总线的概况、分类及主从站的种类的研究可以了解到,PROFIBUS总线应用较多,针对PROFIBUS总线技术研究了主站的结构形式,从站接口分类,PROFIBUS总线通讯协议,以及PROFIBUS总线与自动化系统的连接.     

现场总线技术及其应用研究

对于现场总线的概况、分类及主从站的种类的研究可以了解到,PROFIBUS总线应用较多,针对PROFIBUS总线技术研究了主站的结构形式,从站接口分类,PROFIBUS总线通讯协议,以及PROFIBUS总线与自动化系统的连接。     

PROFIBUS现场总线技术及发展分析

分析PROFIBUS现场总线发展现状，对PROFIBUS-DP现场总线技术的协议结构、通信原理、网络系统结构和设备分类等网络技术问题进行了阐述。将PROFIBUS与基金会现场总线FF、LONWORKS、控制局域网CAN及HART总线等几种目前已成熟的现场总线技术进行比较、分析，提出了PROFIBUS在应用中的几点优势。PROFIBUS与其他网络协议兼容形成开放的系统是PROFIBUS现场总线应用技术及网络的发展趋势。     

过程现场总线Profibus在宽厚板控制系统中的应用

本文介绍了将PROFIBUS总线技术应用到宽厚板控制系统的设计方案及其实现方法。通过研究PROFIBUS总线技术的结构、特点及通讯机理,针对宽厚板生产控制工艺要求,结合实践测试结果,说明PROFIBUS总线技术在宽厚板控制系统中的应用,起到了良好的作用。同时PROFIBUS总线技术的高可靠性、高精确性及维护性,大大提升了宽厚板的生产质量和生产效率,也体现了PROFIBUS总线技术在过程控制领域中的优势。     

多路PROFIBUS—DP数字量输出节点硬件设计

PROFIBUS是一种不依赖于设备生产商的开放式现场总线标准。PROFIBUS—DP主要用于分布式I／O通信和设备级控制系统中。是市场占有率绝对领先的总线技术。目前，我国对于PROFIBUS—DP的研究和应用主要以西门子等公司的成套设备为主．而自主开发的产品比较少，基于这一现状，本文在对PROFIBUS—DP技术进行分析研究的基础上，完成了多路PROFIBUS—DP数字量输出节点硬件的设计并应用于实际系统中，实践证明其应用效果良好。     

PROFIBUS PA在PROFINET中集成的研究

PROFIBUS PA集成到PROFINET中是实际应用的需要,研究了PA在过程自动化中的应用情况,对PROFINET在过程自动化中的应用进行了评估.经过分析得出结论:PROFIBUS PA集成到PROFINET中是必要的.提出了PROFIBUS PA集成到PROFINET中的方法.详细给出了通信服务、协议映射和工程设计方法.可以为PROFIBUS工程人员提供实现的参考.     

基于PROFIBUS过程控制实训系统的实现

论文重点介绍了PROFIBUS通信协议、系统组成和应用领域;提出了一种基于PROFIBUS过程控制实训系统的实现方案,包括系统硬件组成和组态步骤;结果表明该实训系统达到了预期效果。     

PROFIBUS非周期通讯技术在NT6000系统中的实现及应用

PROFIBUS是一种国际化、开放式、不依赖于设备生产商的现场总线标准.目前国产化主站有很多都实现了DPV0功能,但是没有实现DPV1非周期通讯功能.科远智慧经过多年的研究,在自研PROFIBUS协议栈的基础上进行开发,成功实现了PROFIBUS主站的二类非周期通讯功能(MSAC_C2).通过和上位机FDT/AMS软件的配合使用,现场总线主站可以将PROFIBUS DP/PA从站的周期/非周期数据采集到NT6000控制系统中,实现DCS和现场总线技术的完美结合.现场应用表明,非周期通讯模块技术先进,稳定可靠;可以很方便地管理现场PROFIBUS设备,满足客户需求.     

西门子WinCC及S7-400的应用

本文叙述了利用S7-400可编程控制器组建PROFIBUS现场总线的基本过程,并讨论通过PROFIBUS实现S7-400与工控组态软件WinCC之间通讯的方法。     

基于PROFIBUS总线技术的智能化开关柜的研究与开发

针对智能化开关柜的远程控制、故障检测、信息提取等方面的要求，介绍了基于PROFIBUS总线技术的智能化开关柜的研究与开发；设计了模块化的、标准化的开关柜，通过组成PROFIBUS—DP网络结构，建立主／从通信模式，利用软件系统，可靠性的进行数据读取及处理，并对系统的技术特征进行了详细的分析。其研究与开发结果证明，PROFIBUS总线技术在智能化开关柜中具有广泛的应用前景。     

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