武装直升机火控系统仿真转台的综合性能指标调试策略研究

针对武装直升机火控系统仿真转台的综合性能指标,提出了一种新型调试策略．在推导该仿真转台数学模型的基础上,设计了其控制系统的四闭环结构：电流环、速度环、模拟位置环和数字位置环．调试前首先对测速机、电位计等反馈信号进行校准,内回路前向通道采用了串联超前-滞后校正网络．仿真转台各框架的数字位置量反馈采用二十四位补码格式,而数字速度反馈量解算则采用了三点式数值微分算法,在对反馈信号数字鉴频的基础上,对仿真转台的数字位置环进行了变频前馈补偿．仿真测试实验表明,应用本设计的调试策略所研制的武装直升机火控系统仿真转台幅值误差和相位误差均很小,具有较高的频带宽度和良好的跟踪性能,能够满足各项动静态性能指标要求。     

高精度伺服稳定跟踪平台数字控制器研制

以陀螺伺服稳定跟踪平台为背景 ,介绍了以DSP为处理核心的平台数字伺服运动控制器的研制 .指出惯性速率环和电机速度环的本质不同 ;提出增加电机转矩 (电流 )环用于提高电机输出转矩线性度的方法 ,从而达到提高惯性速率稳定环的控制效果 ;介绍了以CCD图像或增量式码盘测角组成系统位置闭环 ,以光纤速率陀螺作为惯性速率反馈传感器组成系统速率闭环 ,附带电流反馈组成电机转矩 (电流 )环和速度、加速度前馈装置的前馈反馈复合控制系统 .组成伺服跟踪平台系统联调后测试结果表明 ,系统具有良好的动、静态性能指标和很好的控制效果 .     

高精度伺服稳定跟踪平台数字控制器研制

以陀螺伺服稳定跟踪平台为背景，介绍了以DSP为处理核心的平台数字伺服运动控制器的研制．指出惯性速率环和电机速度环的本质不同；提出增加电机转矩(电流)环用于提高电机输出转矩线性度的方法，从而达到提高惯性速率稳定环的控制效果；介绍了以CCD图像或增量式码盘测角组成系统位置闭环，以光纤速率陀螺作为惯性速率反馈传感器组成系统速率闭环，附带电流反馈组成电机转矩(电流)环和速度、加速度前馈装置的前馈一反馈复合控制系统．组成伺服跟踪平台系统联调后测试结果表明，系统具有良好的动、静态性能指标和很好的控制效果．     

交流伺服系统位置控制器的仿真研究

在交流伺服控制系统中，采用带速度和加速度前馈的数字PID调节器与数字阶式滤波器构成的复合控制器，可以显著提高控制系统的精度，大大降低跟随误差。仿真结果表明，所设计和复合位置控制器可以实现对位置指令的快速无超调跟踪，且稳态无静差，满足高精度伺服系统控制的要求，是一种切实可行的控制方法。     

基于PMAC的三轴转台的伺服系统设计

介绍了基于PMAC运动控制卡的三轴仿真转台的直流伺服系统设计，给出了转台的基本组成，控制系统的硬件结构，运动控制卡连同驱动器参数的整定方法及控制软件的设计，实现了转台的实时控制以及位置、速度、摇摆等的伺服控制．实际操作表明，该系统满足了转台实时运动控制的要求，运行稳定，操作方便．     

高速伺服注塑机成型过程预测迭代学习控制

将学习控制应用于高精密快速伺服注塑机成型过程，根据成型过程的特点设计了一个预测迭代学习控制器，并利用先前得到的系统模型对算法进行仿真．控制器由前馈和反馈控制两部分组成，引入滤波器用于增强学习控制器的鲁棒性．将预测学习控制算法在伺服注塑机上进行了实验．实验和仿真结果表明，该预测学习算法对提高成型过程的位置重复精度效果明显．     

垂直陀螺180°回转伺服变结构PID控制

为减小垂直陀螺仪的漂移,提高平台罗经系统精度,设计了垂直陀螺180°回转伺服控制系统,采用变结构PID校正网络和角速度数字控制器,实现垂直陀螺仪精确角位置伺服控制和接近匀速的回转．实验结果表明,采用变结构比例、积分、微分(PID)控制方法,可以使旋转机构在0°和180°位置精确定位,有效减小陀螺仪漂移．在对系统动态性能要求不高的情况下,该方案能将稳态绝对误差控制在30″以内,满足设计精度要求．     

基于前馈控制的压电单轴实时位移控制系统

为满足微细加工、超精加工等的实时性、精度要求,基于前馈复合控制,提出一种压电单轴精密位移的嵌入式实时控制系统.建立了压电致动器的阶跃响应模型、迟滞特性的Preisach及逆模型.采用Preisach逆模型作为前馈控制环节、比例积分控制作为反馈环节,设计前馈复合控制器.研制了基于S3C2410控制器的压电单轴实时位移控制系统.测试表明:阶跃响应稳态误差小于0.15 μm,调节时间约1.2 ms,超调量约10％;正弦响应误差为-0.41～0.45 μm,在±1.5％以内;该系统能满足多个领域的实时精确控制要求.     

永磁同步伺服电机的变结构与前馈复合控制

为提高永磁同步伺服电机控制系统的性能,文章阐述了永磁同步电机伺服系统架构并给出了永磁同步电机的数学模型。在此基础上,对传统的三环伺服位置控制进行了分析,给出了各控制环参数的设计准则,并总结了传统伺服控制策略下的特点。随后,针对传统伺服控制系统定位精度低、响应慢的缺陷,在分析研究变结构控制和前馈控制特点的基础上,将其与传统控制相结合,提出了三者控制方式结合的复合控制策略,并对其进行了相应地理论分析。最后,建立了相应的系统仿真控制模型,并进行了测试。结果表明：变结构控制和前馈控制独立作用时均可缩短系统响应时间,而前馈控制还可提高系统的定位精度;同时复合控制结合了两者的优点,既提高了系统位置响应速度又改善了位置跟踪精度。     

云台精密转动控制的研究

针对云台高速、精度等发展特性,本文对云台的伺服系统进行了研究,为了提高系统位置定位的动态性能,提出对三环伺服控制系统加入速度的前馈控制这一方案。首先对无刷直流电机的数学模型进行建立,根据各个控制环路的等效进而建立系统的三环控制系统,并以此来确定加入速度前馈控制的复合控制系统。对两种控制模型进行simulink仿真,输入相同的激励信号后分别对系统的阶跃、斜坡、加速度的信号响应进行对比。对比结果表明,加入速度前馈控制后,不仅可以有效的提高云台控制系统的动态响应,而且同时不会影响到其稳定性。     

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