This paper presents a new technique in the high dielectric constant composite oxide film preparation. On the basis of nano-compsite high dielectric constant aluminum oxide fdm growth technology, a new idea of adultera...This paper presents a new technique in the high dielectric constant composite oxide film preparation. On the basis of nano-compsite high dielectric constant aluminum oxide fdm growth technology, a new idea of adulterating Si oxide species into the aluminum composite film was proposed. As a result, the specific capacitance and withstanding voltage of the composite oxide film formed at the anodizing voltage of 20V are enhanced, and the leakage current of the aluminum composite oxide fdm is reduced through incorporation of Si oxide species.展开更多
Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the ac...Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV·mm–1 were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations(< 2 kV·mm–1) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization.展开更多
Scientists said on Monday they had genetically engineered rice to withstand drought, salt water and cold temperatures by borrowing a gene from the E. coli bacteria. [译文]星期一,科学家们称他们已经利用遗传工程学,借用...Scientists said on Monday they had genetically engineered rice to withstand drought, salt water and cold temperatures by borrowing a gene from the E. coli bacteria. [译文]星期一,科学家们称他们已经利用遗传工程学,借用大肠埃舍利希氏 杆菌的基因培育出了耐干旱、耐咸水、耐严寒的稻米。展开更多
IF there is one name that is familiar to Chinese aged 10 to 80 it is Guo Lanying. Recently a recital was held by CCTV in honor of her 60-year career. When Guo Lanying took the stage, she was met with a lengthy standin...IF there is one name that is familiar to Chinese aged 10 to 80 it is Guo Lanying. Recently a recital was held by CCTV in honor of her 60-year career. When Guo Lanying took the stage, she was met with a lengthy standing ovation. Her voice was choked with emotion. Behind her was a smiling photograph of her that was taken at the start of her opera career. Guo Lanying was born in 1930展开更多
基金This work was supported by the National Nature Science Foundation of China under Grant No.60601006.
文摘This paper presents a new technique in the high dielectric constant composite oxide film preparation. On the basis of nano-compsite high dielectric constant aluminum oxide fdm growth technology, a new idea of adulterating Si oxide species into the aluminum composite film was proposed. As a result, the specific capacitance and withstanding voltage of the composite oxide film formed at the anodizing voltage of 20V are enhanced, and the leakage current of the aluminum composite oxide fdm is reduced through incorporation of Si oxide species.
文摘Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV·mm–1 were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations(< 2 kV·mm–1) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization.
文摘Scientists said on Monday they had genetically engineered rice to withstand drought, salt water and cold temperatures by borrowing a gene from the E. coli bacteria. [译文]星期一,科学家们称他们已经利用遗传工程学,借用大肠埃舍利希氏 杆菌的基因培育出了耐干旱、耐咸水、耐严寒的稻米。
文摘IF there is one name that is familiar to Chinese aged 10 to 80 it is Guo Lanying. Recently a recital was held by CCTV in honor of her 60-year career. When Guo Lanying took the stage, she was met with a lengthy standing ovation. Her voice was choked with emotion. Behind her was a smiling photograph of her that was taken at the start of her opera career. Guo Lanying was born in 1930
