Considering the instability of the output power of photovoltaic(PV)generation system,to improve the power regulation ability of PV power during grid-connected operation,based on the quantitative analysis of meteorolog...Considering the instability of the output power of photovoltaic(PV)generation system,to improve the power regulation ability of PV power during grid-connected operation,based on the quantitative analysis of meteorological conditions,a short-term prediction method of PV power based on LMD-EE-ESN with iterative error correction was proposed.Firstly,through the fuzzy clustering processing of meteorological conditions,taking the power curves of PV power generation in sunny,rainy or snowy,cloudy,and changeable weather as the reference,the local mean decomposition(LMD)was carried out respectively,and their energy entropy(EE)was taken as the meteorological characteristics.Then,the historical generation power series was decomposed by LMD algorithm,and the hierarchical prediction of the power curve was realized by echo state network(ESN)prediction algorithm combined with meteorological characteristics.Finally,the iterative error theory was applied to the correction of power prediction results.The analysis of the historical data in the PV power generation system shows that this method avoids the influence of meteorological conditions in the short-term prediction of PV output power,and improves the accuracy of power prediction on the condition of hierarchical prediction and iterative error correction.展开更多
English articles belong to a category of high frequency words. However, they also have been considered as one of the most difficult part and latest part to be fully acquired by non-native speakers. Because of this rea...English articles belong to a category of high frequency words. However, they also have been considered as one of the most difficult part and latest part to be fully acquired by non-native speakers. Because of this reason, a lot of efforts have been made to research into the acquisition of them. In China, researches on the article system were mainly focused on the analysis of functions and description of the usage. This essay intends to explore the distribution and features of English article errors made by Chinese EFL （English as a Foreign Language） learners both horizontally and longitudinally with the hope to find the possible factors which lead to the errors, so as to throw some light on English articles learning and teaching展开更多
Learning about culture is an integral part of learning a fbreign language. Participating in speech contests gives language learners a good opportunity to know more about the culture of the target language. Such contes...Learning about culture is an integral part of learning a fbreign language. Participating in speech contests gives language learners a good opportunity to know more about the culture of the target language. Such contests allow students to learn how to write a speech for a particular audience, how to introduce a speaker, how to deliver a speech, and how to say ＂thank you＂ to the speaker. Participation in speech contests can promote insight and understanding through a comparison of American culture and the students＇ native culture. Such comparison is intended to promote better understanding of both cultures.展开更多
A novel algorithm for active noise control systems based on frequency selective filters （FSFANC） is presented in the paper. The FSFANC aims at the multi-tonal noise attenuation problem. One FSFANC system copes with ...A novel algorithm for active noise control systems based on frequency selective filters （FSFANC） is presented in the paper. The FSFANC aims at the multi-tonal noise attenuation problem. One FSFANC system copes with one of the tonal components, and several FSFANC systems can run independently in paralld to cancel the selected multiple tones. The proposed algorithm adopts a simple structure with only two coefficients that can be explained as the real and imaginary parts of the structure to model the secondary path, and estimates the secondary path by injecting sinusoidal identification signals. Theoretical analysis and laboratory experiments show that the proposed algorithm possesses stone advantages, such as simpler structure, less computational burden, greater stability, and fast converging speed.展开更多
An inhomogeneously broadened two-mode laser system with cross-correlations between the real and imag- inary parts of quantum noise is considered. The Fokker-Planek equation of the system is derived by the phase-lockin...An inhomogeneously broadened two-mode laser system with cross-correlations between the real and imag- inary parts of quantum noise is considered. The Fokker-Planek equation of the system is derived by the phase-locking method. The steady-state probability distribution, the mean light intensity, the normalization autocorrelation function, and cross correlation function are calculated. The results indicate that： （i） The cross-correlation between the real and imaginary parts of quantum noise can cause the stationary probability distribution from one peak structure to two extrema structure when the laser system is operated above threshold; （ii） The cross-correlation between the real and imaginary parts of quantum noise enhance the light intensity fluctuation and decrease the laser output when the laser system is operated below or near threshold; （iii） The effect of the cross-correlation between the real and imaginary parts of quantum noise is very weak on the stationary properties when the laser system is operated far above threshold.展开更多
基金supported by National Natural Science Foundation of China(No.516667017).
文摘Considering the instability of the output power of photovoltaic(PV)generation system,to improve the power regulation ability of PV power during grid-connected operation,based on the quantitative analysis of meteorological conditions,a short-term prediction method of PV power based on LMD-EE-ESN with iterative error correction was proposed.Firstly,through the fuzzy clustering processing of meteorological conditions,taking the power curves of PV power generation in sunny,rainy or snowy,cloudy,and changeable weather as the reference,the local mean decomposition(LMD)was carried out respectively,and their energy entropy(EE)was taken as the meteorological characteristics.Then,the historical generation power series was decomposed by LMD algorithm,and the hierarchical prediction of the power curve was realized by echo state network(ESN)prediction algorithm combined with meteorological characteristics.Finally,the iterative error theory was applied to the correction of power prediction results.The analysis of the historical data in the PV power generation system shows that this method avoids the influence of meteorological conditions in the short-term prediction of PV output power,and improves the accuracy of power prediction on the condition of hierarchical prediction and iterative error correction.
文摘English articles belong to a category of high frequency words. However, they also have been considered as one of the most difficult part and latest part to be fully acquired by non-native speakers. Because of this reason, a lot of efforts have been made to research into the acquisition of them. In China, researches on the article system were mainly focused on the analysis of functions and description of the usage. This essay intends to explore the distribution and features of English article errors made by Chinese EFL （English as a Foreign Language） learners both horizontally and longitudinally with the hope to find the possible factors which lead to the errors, so as to throw some light on English articles learning and teaching
文摘Learning about culture is an integral part of learning a fbreign language. Participating in speech contests gives language learners a good opportunity to know more about the culture of the target language. Such contests allow students to learn how to write a speech for a particular audience, how to introduce a speaker, how to deliver a speech, and how to say ＂thank you＂ to the speaker. Participation in speech contests can promote insight and understanding through a comparison of American culture and the students＇ native culture. Such comparison is intended to promote better understanding of both cultures.
基金supported by the Independent Innovation Foundation of Shandong University(No.2009JC004)the Natural Science Foundation of Shandong Province(No.Y2007G31)
文摘A novel algorithm for active noise control systems based on frequency selective filters （FSFANC） is presented in the paper. The FSFANC aims at the multi-tonal noise attenuation problem. One FSFANC system copes with one of the tonal components, and several FSFANC systems can run independently in paralld to cancel the selected multiple tones. The proposed algorithm adopts a simple structure with only two coefficients that can be explained as the real and imaginary parts of the structure to model the secondary path, and estimates the secondary path by injecting sinusoidal identification signals. Theoretical analysis and laboratory experiments show that the proposed algorithm possesses stone advantages, such as simpler structure, less computational burden, greater stability, and fast converging speed.
基金Supported by the National Natural Science Foundation of China under Grant No.10865006
文摘An inhomogeneously broadened two-mode laser system with cross-correlations between the real and imag- inary parts of quantum noise is considered. The Fokker-Planek equation of the system is derived by the phase-locking method. The steady-state probability distribution, the mean light intensity, the normalization autocorrelation function, and cross correlation function are calculated. The results indicate that： （i） The cross-correlation between the real and imaginary parts of quantum noise can cause the stationary probability distribution from one peak structure to two extrema structure when the laser system is operated above threshold; （ii） The cross-correlation between the real and imaginary parts of quantum noise enhance the light intensity fluctuation and decrease the laser output when the laser system is operated below or near threshold; （iii） The effect of the cross-correlation between the real and imaginary parts of quantum noise is very weak on the stationary properties when the laser system is operated far above threshold.
