Recently,power electronic transformers(PETs)have received widespread attention owing to their flexible networking,diverse operating modes,and abundant control objects.In this study,we established a steady-state model ...Recently,power electronic transformers(PETs)have received widespread attention owing to their flexible networking,diverse operating modes,and abundant control objects.In this study,we established a steady-state model of PETs and applied it to the power flow calculation of AC-DC hybrid systems with PETs,considering the topology,power balance,loss,and control characteristics of multi-port PETs.To address new problems caused by the introduction of the PET port and control equations to the power flow calculation,this study proposes an iterative method of AC-DC mixed power flow decoupling based on step optimization,which can achieve AC-DC decoupling and effectively improve convergence.The results show that the proposed algorithm improves the iterative method and overcomes the overcorrection and initial value sensitivity problems of conventional iterative algorithms.展开更多
Tarnavas established mixed weighted power mean inequality in 1999. A separation of weighted power mean inequslity was derived in this paper. As its applications, some separations of other inequalities were given.
A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magne...A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, new demands on the new fast control power supply have led to an enhanced ability of fast response and output current, as well as a new control mode. The structure of cascaded and paralleled H-bridges can meet the demand of extended capacity, and digital control can reMize current and voltage mixed control mode. The validity of the proposed scheme is confirmed by experiments.展开更多
Since the decision of the State Council in 1985 on expanding the export of electromechanical products, China’s exports of electrome-chanical products has freed itself from long fluctuation and realized fast growth. A...Since the decision of the State Council in 1985 on expanding the export of electromechanical products, China’s exports of electrome-chanical products has freed itself from long fluctuation and realized fast growth. According to statistics from the Customs Office, China’s exports of electro-mechanical products in 1995 reached US$43.86 billion, increasing 25 times in 10 years, and becoming China’s first pillar products for export. While achieving fast growth in exports, product mix has also seen sig-展开更多
It is proved that if λ_1, λ_2, ···, λ_7are nonzero real numbers, not all of the same sign and not all in rational ratios, then for any given real numbers η and σ, 0 < σ <1/16, the inequalit...It is proved that if λ_1, λ_2, ···, λ_7are nonzero real numbers, not all of the same sign and not all in rational ratios, then for any given real numbers η and σ, 0 < σ <1/16, the inequality |λ_1x^2_1+ λ_2x^2_2+∑7 i=3λ_ix^4_i+ η| <( max1≤i≤7|x_i|)^(-σ)has infinitely many solutions in positive integers x_1, x_2, ···, x_7. Similar result is proved for |λ_1x^2_1+ λ_2x^2_2+ λ_3x^2_3+ λ_4x^4_4+ λ_5x^4_5+ λ_6x^4_6+ η| <( max1≤i≤6|xi|)-σ.These results constitute an improvement upon those of Shi and Li.展开更多
Using a fixed-point method, we establish the generalized Hyers-Ulam stability of a general mixed additive-cubic equation： f（kx ＋ y） ＋ f（kx - y） = kf（x ＋ y） ＋ kf（x - y） ＋ 2f（kx） - 2kf（x） in Banach mod...Using a fixed-point method, we establish the generalized Hyers-Ulam stability of a general mixed additive-cubic equation： f（kx ＋ y） ＋ f（kx - y） = kf（x ＋ y） ＋ kf（x - y） ＋ 2f（kx） - 2kf（x） in Banach modules over a unital Banach algebra.展开更多
The objective of this paper is to show that the German way towards renewable energy production could become an example for successful energy transition in other countries.Based on the Renewable Energy Act(Erneuerbare ...The objective of this paper is to show that the German way towards renewable energy production could become an example for successful energy transition in other countries.Based on the Renewable Energy Act(Erneuerbare Energien Gesetz(EEG))in the year 2000 the most important steps for this transition seemed to be start-ups with relevant and reliable feed-in tariffs,the involvement of“many single”intelligently and digitally connected producers to form a kind of“swarm-energy.”In addition regional smart grids,a national grid structure with sufficient capacity,and,last but not least,implementation of energy efficiency tools in the building,construction and transport sector,are necessary driving sources.展开更多
基金supported by the National Key Research and Development Program of China(2017YFB0903300).
文摘Recently,power electronic transformers(PETs)have received widespread attention owing to their flexible networking,diverse operating modes,and abundant control objects.In this study,we established a steady-state model of PETs and applied it to the power flow calculation of AC-DC hybrid systems with PETs,considering the topology,power balance,loss,and control characteristics of multi-port PETs.To address new problems caused by the introduction of the PET port and control equations to the power flow calculation,this study proposes an iterative method of AC-DC mixed power flow decoupling based on step optimization,which can achieve AC-DC decoupling and effectively improve convergence.The results show that the proposed algorithm improves the iterative method and overcomes the overcorrection and initial value sensitivity problems of conventional iterative algorithms.
基金Project supported by National Natural Science Foundation of China （Grant No. 10271071）
文摘Tarnavas established mixed weighted power mean inequality in 1999. A separation of weighted power mean inequslity was derived in this paper. As its applications, some separations of other inequalities were given.
基金supported by ITER Program of China(973 Program)(No.2011GB109002)National Natural Science Foundation of China(No.11275056)Hefei University of Technology Doctor Research Foundation of China(No.2011HGBZ1292)
文摘A feedback control system is needed to restrain plasma vertical displacement in EAST （Experimental Advanced Superconducting Toknmak）. A fast control power supply excites active feedback coils, which produces a magnetic field to control the plasma＇s displacement. With the development of EAST, new demands on the new fast control power supply have led to an enhanced ability of fast response and output current, as well as a new control mode. The structure of cascaded and paralleled H-bridges can meet the demand of extended capacity, and digital control can reMize current and voltage mixed control mode. The validity of the proposed scheme is confirmed by experiments.
文摘Since the decision of the State Council in 1985 on expanding the export of electromechanical products, China’s exports of electrome-chanical products has freed itself from long fluctuation and realized fast growth. According to statistics from the Customs Office, China’s exports of electro-mechanical products in 1995 reached US$43.86 billion, increasing 25 times in 10 years, and becoming China’s first pillar products for export. While achieving fast growth in exports, product mix has also seen sig-
基金Supported by the National Natural Science Foundation of China(11201107,11271283,11501435)Supported by the Natural Science Foundation of Anhui Province(1208085QA01)
文摘It is proved that if λ_1, λ_2, ···, λ_7are nonzero real numbers, not all of the same sign and not all in rational ratios, then for any given real numbers η and σ, 0 < σ <1/16, the inequality |λ_1x^2_1+ λ_2x^2_2+∑7 i=3λ_ix^4_i+ η| <( max1≤i≤7|x_i|)^(-σ)has infinitely many solutions in positive integers x_1, x_2, ···, x_7. Similar result is proved for |λ_1x^2_1+ λ_2x^2_2+ λ_3x^2_3+ λ_4x^4_4+ λ_5x^4_5+ λ_6x^4_6+ η| <( max1≤i≤6|xi|)-σ.These results constitute an improvement upon those of Shi and Li.
基金supported by the National Natural Science Foundation of China (10671013,60972089,11171022)
文摘Using a fixed-point method, we establish the generalized Hyers-Ulam stability of a general mixed additive-cubic equation： f（kx ＋ y） ＋ f（kx - y） = kf（x ＋ y） ＋ kf（x - y） ＋ 2f（kx） - 2kf（x） in Banach modules over a unital Banach algebra.
文摘The objective of this paper is to show that the German way towards renewable energy production could become an example for successful energy transition in other countries.Based on the Renewable Energy Act(Erneuerbare Energien Gesetz(EEG))in the year 2000 the most important steps for this transition seemed to be start-ups with relevant and reliable feed-in tariffs,the involvement of“many single”intelligently and digitally connected producers to form a kind of“swarm-energy.”In addition regional smart grids,a national grid structure with sufficient capacity,and,last but not least,implementation of energy efficiency tools in the building,construction and transport sector,are necessary driving sources.
