共查询到20条相似文献,搜索用时 78 毫秒
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传统三电平正交坐标系下空间矢量脉宽调制法(SVPWM)在矢量合成过程中,涉及大量函数运算,计算复杂,占用了计算机大量存储空间、导致运算效率下降.为更好的实现编程控制,进行60°坐标系下的SVPWM算法研究,改进和简化传统的SVPWM算法,避免了计算过程中大量的逻辑运算.最后通过对系统进行仿真分析与实验平台验证,结果表明,该算法减少了运算时间,提高了计算精度,更能满足实际工况需求. 相似文献
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一种改进的三电平逆变器空间矢量脉宽调制算法研究 总被引:1,自引:0,他引:1
二极管中点箝位型三电平逆变器广泛用于中高压大容量交流调速系统,具有对器件耐压要求低,输出谐波含量低等优点,但同时存在如何保持中点电压平衡和防止电压跳变等问题.空间矢量脉宽调制(SPVWM)算法能很好地跟踪转矩和磁链的设定值,有效地降低转矩和磁链的脉动,但算法复杂,运算量大.本文在分析了影响三电平逆变器中点电压平衡的主要因素的基础上,提出一种改进的SVPWM算法.该算法用中矢量、长矢量和两个短矢量合成参考矢量,并采用矢量调制的方法,利用短矢量的电流特性,消除中矢量对中点电压的影响,简化了算法,有效地控制了逆变器的中点电压,抑制了电压跳变.仿真结果证明了这种方法的可行性. 相似文献
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针对传统三电平逆变器SVPWM控制策略所存在计算量大,编程实现难度大等问题,本文提出一种改进型的SVPWM算法,该算法的主要思想是将n电平数的逆变器降阶成n-1电平数的逆变器控制方式,实现对其控制,大大简化了计算量。在MATLAB平台上搭建了三相二极管钳位型三电平逆变器改进型SVPWM仿真模型,进行相关仿真实验;采用TMS320F2812作控制器实现了降阶SVPWM调制,实物实验波形和仿真实验结果,都验证了控制策略的可行性和有效性。 相似文献
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微型燃机是靠其内部的永磁同步机系统进行软启动的,而在永磁同步机控制系统中,空间电压矢量调制(SVPWM)是其主要的控制方法之一。针对目前SVPWM算法存在计算工作量大的缺点,提出了一种新型的快速SVPWM控制算法。该算法无需进行复杂运算,只需进行简单的比较和普通运算,就可完成扇区判断和矢量作用时间的计算,解决了常规SVPWM算法中由于三角函数的计算量大而带来的系统性能下降问题。将该算法在100 kW微型燃机软启动系统中进行了实验,并与常规SVPWM算法的通用变频器比较,其结果表明,在启动快速性等性能方面,均优于常规的SVPWM算法。 相似文献
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S. Shaw 《Journal of Computer Assisted Learning》1993,9(2):93-99
Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained. 相似文献
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European Community policy and the market 总被引:1,自引:0,他引:1
C. Lloyd 《Journal of Computer Assisted Learning》1993,9(2):86-91
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven. 相似文献
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融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。 相似文献
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Wayne O’Brien Author Vitae 《Journal of Systems and Software》2008,81(11):1997-2013
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them. 相似文献
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This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives. 相似文献
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Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what
is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic
sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and
its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of
an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify
robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can
or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest.
This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January
31–February 2, 2008 相似文献
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David Poole 《Computational Intelligence》1989,5(2):97-110
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given. 相似文献
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Watts S. Humphrey 《Annals of Software Engineering》2002,14(1-4):39-72
This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)SM and Team Software Process (TSP){SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical. 相似文献
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基于复小波噪声方差显著修正的SAR图像去噪 总被引:4,自引:1,他引:3
提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。 相似文献