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一种定频化的T型三电平并网逆变器模型预测控制研究
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作者 闫富平 《中国新技术新产品》 2023年第1期67-69,共3页
模型预测控制能够根据实际控制目标不同来设计不同的价值函数,基于系统数学模型遍历所有的开关状态进行寻优,最终得到最佳的开关状态并输出。该文将这种控制方法应用于T型三电平并网逆变器之中,同时针对模型预测控制开关频率不固定的缺... 模型预测控制能够根据实际控制目标不同来设计不同的价值函数,基于系统数学模型遍历所有的开关状态进行寻优,最终得到最佳的开关状态并输出。该文将这种控制方法应用于T型三电平并网逆变器之中,同时针对模型预测控制开关频率不固定的缺陷,提出了一种定频化的方法。针对价值函数进行求偏导,得到电压矢量与传统调制策略并进行结合。试验波形验证了该文方案的有效性与正确性。 展开更多
关键词 T型三电平 并网逆变器 预测控制 定频化
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定频化VIENNA整流器模型预测电流控制 被引量:2
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作者 韩会山 靳晨聪 毕艳军 《电气传动》 2021年第5期76-80,共5页
VIENNA整流器是一种高性能三相三电平整流器,不仅网侧性能优良,并且具有功率密度高、结构简单等特点。将模型预测控制引入了VIENNA整流器的电流控制当中,并针对传统模型预测控制计算复杂、开关频率不固定的缺点,提出了一种定频化的模型... VIENNA整流器是一种高性能三相三电平整流器,不仅网侧性能优良,并且具有功率密度高、结构简单等特点。将模型预测控制引入了VIENNA整流器的电流控制当中,并针对传统模型预测控制计算复杂、开关频率不固定的缺点,提出了一种定频化的模型预测电流控制方法,通过优化价值函数、引入调制模块的方式固定开关频率,并实现网侧单位功率因数、输出直流电压稳定和输入电流正弦的目标。实验验证了所提方案的正确性。 展开更多
关键词 VIENNA整流器 模型预测控制 定频化 SPWM调制
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Effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis 被引量:1
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作者 LEI Si-jia 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2006年第7期580-585,共6页
The effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis, were investigated. Four ration levels 1.5%, 2.5%, 4.0% and satiation (6.0% BW/d) were used. Ap... The effects of ration level and feeding frequency on digestibility in juvenile soft-shelled turtle, Pelodiscus sinensis, were investigated. Four ration levels 1.5%, 2.5%, 4.0% and satiation (6.0% BW/d) were used. Apparent digestibility (AD) of dry matter (DMAD), protein (PAD) and protein real digestibility (PRD) were significantly affected by ration level, but not by feeding frequency when the ration level was similar. However, the feeding frequency affected the AD, DMAD, PAD and PRD significantly when the turtles were fed to satiation. The relationship between fecal protein content (Y) and protein intake (At) can be expressed as a quadric equation: Y=-0.1742+0.1476X-0.0003X^2 (r^2=0.876, n=27, F=93.92, P〈0.01). 展开更多
关键词 DIGESTIBILITY Ration level Feeding frequency Juvenile soft-shelled turtle Pelodiscus sinensis
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Frequency—Locking in Coupled Chaotic Systems
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作者 HUBam-Bi LIUZong-Hua 《Communications in Theoretical Physics》 SCIE CAS CSCD 2001年第4期425-430,共6页
A novel approach is presented for measuring the phase synchronization (frequency-locking) of coupled nonidentical oscillators, which can characterize frequency-locking for chaotic systems without well-defined phase b... A novel approach is presented for measuring the phase synchronization (frequency-locking) of coupled nonidentical oscillators, which can characterize frequency-locking for chaotic systems without well-defined phase by measuring the mean frequency. Numerical simulations confirm the existence of frequency-locking. The relations between the mean frequency and the coupling strength and the frequency mismatch are given. For the coupled hyperchaotic systems, the frequency-locking can be better characterized by more than one mean frequency curves. 展开更多
关键词 frequency-locking mean frequency hyperchaotic system
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Understanding the commonalities and differences in genomic organizations across closely related bacteria from an energy perspective 被引量:1
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作者 MA Qin CHEN Xin +5 位作者 LIU Chao MAO XiZeng ZHANG HanYuan JI Fei WU ChunGuo XU Ying 《Science China(Life Sciences)》 SCIE CAS 2014年第11期1121-1130,共10页
The availability of a large number of sequenced bacterial genomes facilitates in-depth studies about why genes(operons)in a bacterial genome are globally organized the way they are.We have previously discovered that(t... The availability of a large number of sequenced bacterial genomes facilitates in-depth studies about why genes(operons)in a bacterial genome are globally organized the way they are.We have previously discovered that(the relative)transcription-activation frequencies among different biological pathways encoded in a genome have a dominating role in the global arrangement of operons.One complicating factor in such a study is that some operons may be involved in multiple pathways with different activation frequencies.A quantitative model has been developed that captures this information,which tends to be minimized by the current global arrangement of operons in a bacterial(and archaeal)genome compared to possible alternative arrangements.A study is carried out here using this model on a collection of 52 closely related Escherichia coli genomes,which revealed interesting new insights about how bacterial genomes evolve to optimally adapt to their environments through adjusting the(relative)genomic locations of the encoding operons of biological pathways once their utilization and hence transcription activation frequencies change,to maintain the above energy-efficiency property.More specifically we observed that it is the frequencies of the transcription activation of pathways relative to those of the other encoded pathways in an organism as well as the variation in the activation frequencies of a specific pathway across the related genomes that play a key role in the observed commonalities and differences in the genomic organizations of genes(and operons)encoding specific pathways across different genomes. 展开更多
关键词 genomic organization transcription activation frequency pathway modeling comparative genomics analysis
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Ab initio simulation of the sum-frequency generation response of optically active liquids in the presence of a dc electric field —determination of the absolute molecular configuration
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作者 CHAMPAGNE Benot QUINET Olivier 《Science China Chemistry》 SCIE EI CAS 2014年第10期1405-1408,共4页
Quantum chemical computations have been performed to evaluate the first and second hyperpolarizability quantities of the interference term, linear in the external static electric field, that appear in the electric fie... Quantum chemical computations have been performed to evaluate the first and second hyperpolarizability quantities of the interference term, linear in the external static electric field, that appear in the electric field-induced sum-frequency generation signal of chiral liquids. These are performed at the time-dependent Hartree-Fock level on the prototypical 1,1′-bi-2-naphtol chiral species. 展开更多
关键词 second and third hyperpolarizabilities chirality nonlinear optics time-dependent Hartree-Fock
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Quantization of black hole entropy from unstable circular null geodesics
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作者 Shao-Wen Wei Yu-Xiao Liu Chun-E Fu 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2016年第4期29-36,共8页
The quasinormal mode frequencies can be understood from the massless particles trapped at the unstable circular null geodesics and slowly leaking out to infinity. Based on this viewpoint, in this paper, we semiclassic... The quasinormal mode frequencies can be understood from the massless particles trapped at the unstable circular null geodesics and slowly leaking out to infinity. Based on this viewpoint, in this paper, we semiclassically construct the entropy spectrum of the static and stationary black holes from the null geodesics. The result shows that the spacing of the entropy spectrum only depends on the property of the black hole in the eikonal limit. Moreover, for a black hole far from the extremal case, the spacing is found to be smaller than 2π for any dimension, which is very different from the result of the previous work by using the usual quasinormal mode frequencies. 展开更多
关键词 black hole entropy spectrum null geodesics quantization
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A Model of Irregular Impurity at the Surface of Nanoparticle and Catalytic Activity
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作者 I.V.Blinova V.V.Gusarov I.Yu.Popov 《Communications in Theoretical Physics》 SCIE CAS CSCD 2012年第7期55-58,共4页
A problem of nanocatalyst improvement is considered. The existence of irregularities at the surface of nanoparticle leads to the increasing of the surface/volume ratio and, correspondingly, to the improvement of the c... A problem of nanocatalyst improvement is considered. The existence of irregularities at the surface of nanoparticle leads to the increasing of the surface/volume ratio and, correspondingly, to the improvement of the catalytic activity. But this impurity gives one an additional effect due to the change of the electronic density at the surface. We suggest simple model for the description of this effect. The model allows one to find the discrete spectrum of the Schrdinger operator for nanoparticle. Due to this impurity induced bound states the electron density increases near the surface. It leads to the increase of the catalytic activity of nanoparticles with surface impurities. 展开更多
关键词 semi-infinite crystal operator spectrum IMPURITY catalytic activity NANOPARTICLE
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