The aim of this paper is to study a class of strongly rpp semigroups with normal idempotent bands, so called NBe rpp semigroups. The structure of such semigroups is established in terms of C rpp semigrou...The aim of this paper is to study a class of strongly rpp semigroups with normal idempotent bands, so called NBe rpp semigroups. The structure of such semigroups is established in terms of C rpp semigroups and normal bands.展开更多
利用2014年8月5日江淮地区一次产生多个双极性窄脉冲事件(narrow bipolar event,NBE)的雷暴个例,结合空基资料(TRMM卫星,NCEP/CPC Global IR Dataset)和地基资料(闪电探测和多普勒雷达回波数据),讨论了NBE与雷暴相关参数的关系以及位于...利用2014年8月5日江淮地区一次产生多个双极性窄脉冲事件(narrow bipolar event,NBE)的雷暴个例,结合空基资料(TRMM卫星,NCEP/CPC Global IR Dataset)和地基资料(闪电探测和多普勒雷达回波数据),讨论了NBE与雷暴相关参数的关系以及位于不同雷暴区域NBE的孤立性和辐射强度.结果表明,NBE主要发生在云顶温度小于210 K、极化修正亮温(PCT-85)小于100 K的雷暴对流旺盛区域.通过分析NBE与30 dBZ多普勒雷达回波最大发展高度及闪电频次的关系,发现NBE主要发生于闪电频次较高时期,且NBE与闪电频次的相关性强于其与30 dBZ雷达回波最大高度的相关性.对NBE孤立性及VLF/LF波段辐射强度的分析表明,大多数孤立NBE发生于雷暴发展期,位于20 dBZ及以下的NBE辐射强度最大且最孤立.展开更多
The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescen...The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.展开更多
Since the 1980s,China has entered an era of transformation which has extended its reach to education and school reforms.The“New Basic Education”(NBE)was born in this era and implemented by the East China Normal Univ...Since the 1980s,China has entered an era of transformation which has extended its reach to education and school reforms.The“New Basic Education”(NBE)was born in this era and implemented by the East China Normal University together with schools around the country.NBE aims at nurturing the active,healthy development of a new generation of Chinese people,focusing on classroom teaching and reform,and life practice within the classroom,as well as a reconstruction of school management.A breakthrough has been made with the development of a system that is suitable for the practice of education in China.展开更多
China’s first biomass electricity company focuses on helping farmers as it strives to expand In April 2011,the world’s largest biomass power company,China National Bio Energy Co.Ltd.(NBE),began building a biomass po...China’s first biomass electricity company focuses on helping farmers as it strives to expand In April 2011,the world’s largest biomass power company,China National Bio Energy Co.Ltd.(NBE),began building a biomass power plant in Shangcai County of central China’s Henan Province.The new plant,due to展开更多
Here we report characteristics of more than 100 cases of Narrow Bipolar Events(NBEs)occurred during two thunderstorms on the basis of our analysis of the dataset collected by a GPS based three-station time of arrival(...Here we report characteristics of more than 100 cases of Narrow Bipolar Events(NBEs)occurred during two thunderstorms on the basis of our analysis of the dataset collected by a GPS based three-station time of arrival(TOA)lightning location system deployed in Northeast China during the summer of 2010.All of the NBEs were of positive polarity and the amplitude of VLF/LF initial pulse of NBE was comparable to that of return strokes.The waveform characteristics of 166 NBEs that occurred within 150 km were consistent with the results of other reports.The average value of initial peak width of the bipolar pulse is 7.8±1.5 μs,full width at half maximum is 4.6±1.0 μs,and the ratio of initial peak amplitude to overshoot peak is 2.1±0.6.The inferred source height of NBEs occurred in two thunderstorms averaged 9.6 and 7.4 km above mean sea level,whereas the corresponding virtual ionosphere heights at two different times were 89 and 78 km,respectively.In NBEproducing thunderstorms,NBEs tended to burst during the active stage of normal lightning;nevertheless,no determinate quantitative relations could be established between them.In Storm 0711,NBEs were inclined to cluster at the proximity of particular convective cores with high radar reflectivity,and NBEs tended to move consistently at the front area of those NBE-producing convective cores during the evolution of thunderstorm.展开更多
文摘The aim of this paper is to study a class of strongly rpp semigroups with normal idempotent bands, so called NBe rpp semigroups. The structure of such semigroups is established in terms of C rpp semigroups and normal bands.
文摘The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.
基金This research was supported as part of the Key Project for Humanities and Social Sciences and approved by the Ministry of Education of PRC(11JJD880034):Basic Education Reform and the Development of Innovative“Life/Practice”Educational Research.
文摘Since the 1980s,China has entered an era of transformation which has extended its reach to education and school reforms.The“New Basic Education”(NBE)was born in this era and implemented by the East China Normal University together with schools around the country.NBE aims at nurturing the active,healthy development of a new generation of Chinese people,focusing on classroom teaching and reform,and life practice within the classroom,as well as a reconstruction of school management.A breakthrough has been made with the development of a system that is suitable for the practice of education in China.
文摘China’s first biomass electricity company focuses on helping farmers as it strives to expand In April 2011,the world’s largest biomass power company,China National Bio Energy Co.Ltd.(NBE),began building a biomass power plant in Shangcai County of central China’s Henan Province.The new plant,due to
基金supported by the R&D Special Fund for Public Welfare Industry(Grant GYHY:(forestry) 200704027 and (meteorology) GYHY201006005)National Natural Science Foundation of China (Grant Nos. 41075001 and 40775003)
文摘Here we report characteristics of more than 100 cases of Narrow Bipolar Events(NBEs)occurred during two thunderstorms on the basis of our analysis of the dataset collected by a GPS based three-station time of arrival(TOA)lightning location system deployed in Northeast China during the summer of 2010.All of the NBEs were of positive polarity and the amplitude of VLF/LF initial pulse of NBE was comparable to that of return strokes.The waveform characteristics of 166 NBEs that occurred within 150 km were consistent with the results of other reports.The average value of initial peak width of the bipolar pulse is 7.8±1.5 μs,full width at half maximum is 4.6±1.0 μs,and the ratio of initial peak amplitude to overshoot peak is 2.1±0.6.The inferred source height of NBEs occurred in two thunderstorms averaged 9.6 and 7.4 km above mean sea level,whereas the corresponding virtual ionosphere heights at two different times were 89 and 78 km,respectively.In NBEproducing thunderstorms,NBEs tended to burst during the active stage of normal lightning;nevertheless,no determinate quantitative relations could be established between them.In Storm 0711,NBEs were inclined to cluster at the proximity of particular convective cores with high radar reflectivity,and NBEs tended to move consistently at the front area of those NBE-producing convective cores during the evolution of thunderstorm.
