基于HART协议的工业无线监控系统设计

针对基于HART协议工业仪表数据远程有线传输易受现场恶劣环境影响的问题,将工业无线通信技术应用于现场监控,设计了一种基于HART协议的无线网络监控系统,采用ATM91SAM7X256微处理器和XBee为无线通信控制模块.系统测试结果表明,该系统现场数据采集准确性高,生产运行控制管理安全可靠.     

无线传感器网络协议的研究

在对无线传感器网络分析研究的基础上,阐述了新兴的ZigBee技术标准协议栈的架构。以工业现场实时温度数据采集为背景,利用ZigBee终端设备和协调器组网完成了温度数据采集任务,实验证明,ZigBee技术是有效的无线传感器网络组网技术。     

无线传感器网络研究

从无线传感器网络的概念、发展历程和特点,剖析了其节点以及网络体系结构、算法和协议等研究热点,并对广泛的应用领域做了描述。     

基于WirelessHART的监控系统设计

随着无线技术的日渐成熟,无线技术在工业中的应用也愈来愈广泛.针对工业现场中广泛使用的HART现场总线作了相应的研究,并在HART的基础上对WirelessHART进行了研究.提出利用WirelessHART无线模块,设计一种WirelessHART适配器,并在WirelessHART 适配器的基础上搭建一个上位机监控系统,完成了基于WirelessHART的监控系统的设计.     

HART协议在智能电磁流量计中的实现

现场总线控制系统代表了工业控制系统向分散化、网络化、智能化发展的方向.为构建现场总线型工业测控系统,要求系统中所有仪表都应具有现场总线功能.其中,HART总线技术在电磁流量仪表中应用最为广泛,本文在对HART协议进行详细分析的基础上,重点介绍了系统设计结构以及HART协议在智能电磁流量计中的软硬件实现方法.测试结果表明,该设计满足现场实际要求,达到了设计目的.     

无线应用协议体系结构及其应用

无线应用协议产生于移动通信技术与Internet技术交汇处,为在移动通信网上创建灵活、先进的服务制定了行业统一的规范.无线应用协议采用分层的协议体系结构,为创建基于移动通信设备的应用提供了可升级、可扩充的应用开发环境.     

一种高吞吐量的无线传感器网络多信道MAC协议

针对工业现场环境下无线传感器网络易受干扰而导致可靠性和吞吐量降低的问题,提出了一种基于单接口的多信道MAC层协议.该协议针对分簇式网络,采用改进的MMSN算法为各簇分配簇内通信基础信道,保证网内任意相邻簇信道互异,避免邻簇间的干扰,并在通信过程中根据实际信道质量和干扰强度动态分配簇内节点的通信信道,在抵御干扰的同时提高了信道的利用率.仿真结果表明,相比传统的MAC协议,该协议能有效提高无线传感器网络的吞吐量和抗干扰性.     

医疗监护中基于分段TCP协议无线传输方式的设计

讨论了无线网络技术在医疗监护中的应用,并使用IEEE 802.15.4标准对低速率无线个人局域网作为医疗信息通信传输平台的适用性进行评估.根据医疗信息的特点,对传统的无线传输协议(TCP协议)和Snoop算法加以改进,通过加入时间戳的方式提高分段式TCP数据包传输效率和点到点的数据吞吐量,降低传输平均延迟.仿真实验表明,改进后的Snoop算法提高了低速率无线网络传输方式在医疗应用的传输效率.     

EPA无线工业控制系统的任务调度算法

针对基于EPA标准的工业控制系统底层使用无线通信技术时,传统的实时调度机制不适应无线工业应用的特点,很难达到原有的效果等问题.以解决无线工业控制系统通信任务的超时现象为目的,提出了适合无线EPA标准的任务调度算法.利用启发式机制搜索合理的通信任务预留时间,并根据预留时间进行功能任务和通信任务的联合调度.最后,分析了基于该方法的一个应用实例,该调度方法有效地延长了通信任务的截止时间,进而补偿了无线技术在工业恶劣环境中出现的信道传输质量极不稳定带来的实时性较差等负面影响.     

无线传感器网络在数控机床监测中的应用

数控机床远程监测是目前工业自动化领域所关注的热点。传统的基于总线或LAN方式存在较多问题,如对现场环境要求严格等。随着无线传感器网络(WSN)技术的成熟,可以将网络节点完全集成在一个芯片中,这样就大大拓宽了无线传感器网络技术的应用范围。本文的研究内容是利用现有设备搭建基于IEEE802.15.4/ZigBee协议的无线传感器网络原型,并分析了实现的关键技术。同时结合工程实际,给出了一个无线传感器在数控机床监控领域的应用实例。     

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.     

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     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has