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研究了方波电流驱动的永磁无刷电机交流伺服系统。系统采用电流、速度和位置三闭环结构,并由8098单片机实现位置闭环控制。文中分析了系统的工作原理,设计了硬件电路和双模控制算法。最后给出系统实验结果。 相似文献
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温景国 《太原理工大学学报》1999,30(1):57-59,101
根据SRD系统闭环控制及调速特性,分析以单片机为核心的SRD系统中的闭环控制问题,提出了51系列单片机为核心的SRD系统闭环控制参数的获得方法。 相似文献
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数字闭环控制电液速度伺服系统的仿真及实验研究 总被引:2,自引:0,他引:2
计算机应用数字闭环控制的电液速度伺服系统进行了仿和实验研究,建立了该系统完整的数学和仿真模型,研究表明,仿与实验结果非常一致,建立的仿真模型完全能够描述真实物理系统的运动特征。 相似文献
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从转速电流双闭环控制的串级调速系统的有关参数分析入手,通过对常规处理非定常参数后系统性能的分析,提出了单片机在线编程技术在患级调速系统中非定常参数定常处理上的应用,从而提高了系统的动态性能和控制性能。 相似文献
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基于励磁电流环的功率因数控制策略研究 总被引:1,自引:0,他引:1
本文分析了单闭环控制的同步发电机励磁系统的特点,指出了其存在的部题.以提高励磁系统动静态性能指标为原则,提出了基于励磁电流环的功率因数控制策略,并对其动静态性能进行了分析,理论分析及实际运行结果均验证了该方案的正确性. 相似文献
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王辉 《湖南大学学报(自然科学版)》1994,21(1):61-68
转差频率控制是异步电动机变频调速系统转矩控制的重要方法,本文从讨论转差频率控制原理及转差闭环高速系统的控制结构出发,研究了异步电动机数学模型的工程简化及电压型变频高速系统转差闭环控制的动态设计问题,提出了类似直汉高速系统动态设计的工程设计方法,经仿真研究证明了该方法的可行性。 相似文献
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研究了旋转导向井下闭环钻井系统RCLD控制系统的设计及工作原理。结果表明:这种系统利用钻井液作为控制动力,使系统具有自行动力供应能力,并根据控制指令,控制其摇动幅度和平衡位置,从而达到改变导向力方向和大小的目的,进而实现井眼轨迹的闭环控制。 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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。 相似文献
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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. 相似文献
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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. 相似文献
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Miao Maosheng 《华南师范大学学报(自然科学版)》2014,(6)
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- 相似文献
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Yang Weitao 《华南师范大学学报(自然科学版)》2014,46(6):137-138
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- 相似文献
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Bernard Kirtman 《华南师范大学学报(自然科学版)》2014,(6)
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 相似文献