基于PCI-1750数据采集卡的步进电机控制系统设计

为了方便可靠地控制步进电机,设计了基于"PC+数据采集控制卡"的系统控制方案.通过VC++6.0调用数据采集控制卡中的运动函数库,动态改变脉冲频率,控制电动机的转向和转速,实现步进电机的多轴运动控制.实验表明该控制系统能够很好地满足控制要求.     

基于预测自适应的永磁同步电机无传感器控制

针对传统永磁同步电机无传感器控制动态性能差和转速信号观测精度低的问题,设计了新型永磁同步电机无传感器控制方法.文章采用在线梯度下降法设计二阶线性扩张状态观测器,该二阶线性扩张状态观测器能够在永磁同步电机负载扰动或转速突变情况下准确快速对电机转速实时估计;同时将预测自适应滑模控制系统应用于转速环节,通过预测自适应估计永磁同步电机扰动变化量进行实时电流补偿.仿真结果表明:二阶线性扩张状态观测器能够对转速准确快速实时估计,且抗干扰能力强;预测自适应滑模控制策略有效缩短电机速度响应时间,显著削弱电机转速、电磁转矩的抖振,表现出良好的动态性和鲁棒性.     

三相交流异步电机矢量控制系统仿真建模

分析了三相交流异步电机的数学模型,介绍了三相交流异步电机的矢量控制原理.采用模块式设计方法和结构化设计方法,开发了基于MATILAB/SIMULINKV参数化三相交流异步电机矢量控制仿真模型.该模型的输入参数为电机转子目标转速和转子实时转速,输出参数为电机输出转矩.基于建立的仿真模型开展了电机空载变速过程和恒速加载过程仿真.仿真结果表明,所设计的仿真模型能够实现电机运动过程中转速和转矩的准确计算;所设计的参数化仿真模型可用于三相交流异步电机矢量控制系统仿真研究.     

dSPACE电机控制平台的设计与矢量控制实现

电机的数学模型一般较复杂,离线仿真出来的算法在实际应用中较难得到理想的结果.利用dSPACE与Simulink无缝连接技术,可以实现离线仿真到半实物仿真的快速过渡,提高运动控制系统研究工作的效率.本文介绍了dSPACE的软硬件环境,设计出dSPACE到主驱动的转接电路,并完成电机控制实验平台的搭建;最后在此平台上实现了异步机定子磁链定向的矢量控制,验证了实验平台的高效性.     

基于DS18B20温度监测报警系统的设计与实现

基于DS18B20的温度监测报警系统是以51单片机为控制核心,利用DS18B20温度传感器实时监测环境温度,并把结果在LCD1602液晶显示屏上显示。当温度超出限定范围时,LED灯发光,进行报警。用Proteus和Keil软件联合对该设计进行功能仿真,并在单片机实验板上实现了该报警系统。     

基于实时仿真器的电机控制平台的开发

本文基于通用实时仿真器(UREP),开发了该电机控制平台,并在该平台设计了开环变压变频调速系统。先进行Matlab/Simulink离线仿真,然后在实验室的样机上进行了实验验证。实验结果和离线仿真结果一致,实现了电机电压和频率的实时控制,以及转速、转矩、电压和电流量的采集。为更进一步的研究奠定了基础。     

虚拟手术仿真系统碰撞检测及其形变的研究

设计了一套用于外科医生手术仿真训练的具有实时力反馈的虚拟手术仿真系统.阐述了反馈设备通过带有力/位置传感器的单自由度的机械手和电机控制电路实现实时模拟手术仿真的位置采集和力反馈功能.通过碰撞检测、非线性力反馈计算和软组织形变计算等算法实现逼真的视觉反馈功能.仿真实验表明该系统提供了实时的视觉反馈,具有很强的真实感.     

基于DSP异步电机无速度传感器仿真与实验研究

为提升异步电机矢量控制系统的可靠性和减少系统成本,介绍了基于DSP的异步电机无速度传感器控制系统的设计。在异步电机的转子磁场定向矢量控制系统中,为了完成无速度传感器矢量控制,利用基于反电势积分的控制算法对电机的实时转速进行实时估计。通过MATLAB/Simulink仿真研究了反电势积分算法的效果,使用实验室搭建的拖动系统实验平台对算法进行了实验验证。仿真和实验验证了此控制方案具有很好的实际效果。     

基于FPGA的温度控制系统设计与实现

基于FPGA与温度传感器DS18B20设计实现了单回路水箱温度PID控制系统.软件主要包括PID控制算法及PWM波产生模块、DS18B20驱动模块、数码管显示驱动模块等3个模块.仿真结果验证了设计的正确性.实验结果表明,系统输出温度达到微小超调的稳定控制要求.体现了该设计方法的有效性和实用性.     

金属零件激光直接快速成型制造技术实现

以圆拄形金属零件激光直接快速成型为实倒,阐述了激光直接快速成型技术工艺参数的确定方法,并给出数控平台移动位移、驱动速度、驱动加速度与脉冲、脉冲频率、脉冲频率变化率之间的对应关系.以VC6.0为二次开发平台,采用PCI1240运动控制卡和步进电机驱动器对步进电机的旋转运动进行控制,以完成被加工零件需要的平面由线扫描运动和分层间歇运动.     

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