利用RS232-CAN总线转换器实现多机通讯

RS232通讯距离短,而且只能进行点到点通讯,不能直接组建多点通讯网络。为了延长RS232的通讯距离,并将RS232节点组成通讯网络,目前广泛使用RS232/RS485信号转换器。但是,由于RS485通讯本身的局限性,在实际应用中存在许多不足。为此,可以将RS232通讯网络转换成CAN通讯网络,以更好地解决用户建立远程通讯网络的问题。     

基于STM32的直流充电桩控制系统设计

设计了一种双枪直流充电桩的电气结构,阐述了其单枪和双枪工作原理,提出了一种双枪充电桩的均充和轮充的输出控制策略。详细阐述了以STM32F407ZGT6处理器为核心的主控制系统应具有的基本功能及其主要的控制流程,分析各程序模块的功能。完成了主控制系统的硬件电路设计,包括CAN通讯、RS485、RS232等总线接口电路,并进行板上CAN接口电路的验证,通过ST官方库函数编程实现CAN在回环模式下的自发自收。通过软件设计,进而实现充电过程中的电气连接确认、电压电流等输出控制、电量计量、人机交互、刷卡结算等功能,满足电动汽车双枪直流充电桩系统的基本功能要求,提高控制智能化水平。     

基于CAN总线的轨道衡计量系统设计

提出了基于CAN总线的轨道衡数据采集系统。系统以MAX187为模数转换器件,对传感器信号进行采样。采样值通过CAN收发器发送到CAN总线上,通过RS232接口输出到上位机。测试结果表明,利用CAN总线通信解决了通信误差大、通讯速度慢等问题,能够实现长期有效的快速传输,满足轨道衡实时数据传输的要求。     

现场总线技术在数据采集与监控系统中的应用

本文介绍了CAN、工业以太网、RS485等的各种通讯技术及基于这些通讯技术的DeviceNet、CANOpen、MODBUS、ProfiBus等现场总线,研究了它们的优点及其在工业监控领域的应用现状,进而提出了一种基于CANOpen、MODBUS的数据采集与监控系统。     

基于RS485总线技术的PC机与单片机多机通讯设计

采用SN75LBC184来实现RS232C与RS485串行口的转换,从而使PC机具备主从式多机通讯功能,实现对多个单片机组成数据采集终端的通讯与管理.约定一种简单和有效的串口通讯协议,根据这种通讯协议设计出单片机与PC机串口通讯程序.     

数字式微机继电保护测控装置研究

数字式微机继电保护测控装置是应用电子技术、计算机技术、电力自动化技术、通讯技术为一体的变电站自动化测控装置。采用了系统化设计思想,保护、测量、控制、监测、通讯显示等功能整体设计,在变电站、发电厂构成综合自动化系统,且广泛应用于电力、国防、化工等领域。采用先进的DSP数字信号处理技术、分层分布式结构、开放的CAN总线和RS485网络接口技术实现保护数据在数据总线上交换,配合监控软件组成变电站自动化系统。     

双端CAN总线与DSP单端CAN总线报文转发的实现

由于CAN通讯控制器采用半双工方式通讯,若将通讯控制器的接收端和发送端相连,可简化设计亦能够实现通讯,但是无法与收发器连接,从而缩短了通讯距离并降低了抗干扰性.若要与收发器连接,需使用CAN通讯控制器将报文转发.论述了两种CAN总线之间报文转发板的硬件结构及软件设计,并详细说明报文转发的实现方法.     

基于Nios II的随钻声波测井仪通讯接口卡设计

针对随钻声波测井仪器通讯接口的特点设计了一种随钻声波测井仪器通讯接口卡,该通讯接口卡基于Nios Ⅱ嵌入式硬件核心,以uClinux嵌入式操作系统为控制软件运行平台,通过自定义CAN控制器接口IP内核及相应的CAN引擎驱动程序,实现以太网与CAN总线、以太网与MWD总线之间的数据转发功能,满足了随钻声波测井仪器研发调试和野外现场施工的需求。     

CAN总线在多通道电液力协调加载系统中的应用

将CAN总线和微控制器技术应用到多通道电液力协调加栽控制系统中,给出了基于CAN总线的控制系统硬件和软件设计.介绍了系统的整体结构、CAN总线节点设置、通讯协议和软件设计.运用Labview软件开发了上位机CAN通信卡的驱动程序.     

基于CAN总线的电力机车辅助变流器控制系统设计

本文基于CAN总线,对神朔铁路SS4机车的辅变控制管理系统进行研究,分析了辅变系统的工作原理,给出系统的CAN总线方案、硬件电路设计、CAN通讯协议,并实现了远距离、高可靠性通信功能和远程监控功能。实验表明,基于CAN总线的辅变系统控制更加方便、操作更加安全,提高了电力机车的控制性能、使用寿命。     

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