Large high-dimensional data have posed great challenges to existing algorithms for frequent itemsets mining.To solve the problem,a hybrid method,consisting of a novel row enumeration algorithm and a column enumeration...Large high-dimensional data have posed great challenges to existing algorithms for frequent itemsets mining.To solve the problem,a hybrid method,consisting of a novel row enumeration algorithm and a column enumeration algorithm,is proposed.The intention of the hybrid method is to decompose the mining task into two subtasks and then choose appropriate algorithms to solve them respectively.The novel algorithm,i.e.,Inter-transaction is based on the characteristic that there are few common items between or among long transactions.In addition,an optimization technique is adopted to improve the performance of the intersection of bit-vectors.Experiments on synthetic data show that our method achieves high performance in large high-dimensional data.展开更多
Since its installation on the International Space Station(ISS)in mid-May 2011,the Alpha Magnetic Spectrometer(AMS)has spent over two years on orbit,fully operational,collecting an enormous amount of data including the...Since its installation on the International Space Station(ISS)in mid-May 2011,the Alpha Magnetic Spectrometer(AMS)has spent over two years on orbit,fully operational,collecting an enormous amount of data including the temperatures from the on-board 1118 sensors for thermal control.A large database is continuously updated and analyzed to understand the thermal behavior of the experiment in the space environment and its interaction with the ISS.This paper specifies the design,building,analysis and testing of the thermal control system and its various components for an overview of the AMS thermal control system and its space environment.Also given are some examples of analysis and correlation of the space environmental and ISS parameters with the thermal behaviors of various AMS components.展开更多
A dedicated 24 h S/X dual-band geodetic very long baseline interferometry(VLBI) experiment was conducted in January 2015 with the goal of improving the position estimates for the Chinese Deep Space Station Kashi. Prev...A dedicated 24 h S/X dual-band geodetic very long baseline interferometry(VLBI) experiment was conducted in January 2015 with the goal of improving the position estimates for the Chinese Deep Space Station Kashi. Previously, the position estimates had been only accurate to ~20 cm, which is insufficient for future Chinese deep space explorations. The experiment design and data reduction are described with special emphasis on the limited frequency ranges of Kashi for bandwidth synthesis. A narrowed multi-band delay search window based on post-fit residuals was utilized to resolve the sub-ambiguities due to the drop of a frequency channel in fringe fit, which saved ~22% of the observations from the affected baseline. Final position estimates of Kashi were obtained from the global solution by using more than 5300 international VLBI sessions from August 1979 to September 2015, and estimates were found to be accurate to about 10, 25, and 20 mm in the X, Y, and Z components. Various statistical tests were run, and the estimates and precisions are believed to be reliable.展开更多
基金The work was supported in part by Research Fund for the Doctoral Program of Higher Education of China(No.20060255006)
文摘Large high-dimensional data have posed great challenges to existing algorithms for frequent itemsets mining.To solve the problem,a hybrid method,consisting of a novel row enumeration algorithm and a column enumeration algorithm,is proposed.The intention of the hybrid method is to decompose the mining task into two subtasks and then choose appropriate algorithms to solve them respectively.The novel algorithm,i.e.,Inter-transaction is based on the characteristic that there are few common items between or among long transactions.In addition,an optimization technique is adopted to improve the performance of the intersection of bit-vectors.Experiments on synthetic data show that our method achieves high performance in large high-dimensional data.
文摘Since its installation on the International Space Station(ISS)in mid-May 2011,the Alpha Magnetic Spectrometer(AMS)has spent over two years on orbit,fully operational,collecting an enormous amount of data including the temperatures from the on-board 1118 sensors for thermal control.A large database is continuously updated and analyzed to understand the thermal behavior of the experiment in the space environment and its interaction with the ISS.This paper specifies the design,building,analysis and testing of the thermal control system and its various components for an overview of the AMS thermal control system and its space environment.Also given are some examples of analysis and correlation of the space environmental and ISS parameters with the thermal behaviors of various AMS components.
基金supported by China’s Lunar Exploration Key Techniques Research Program (Grant No. TY3Q20100009)
文摘A dedicated 24 h S/X dual-band geodetic very long baseline interferometry(VLBI) experiment was conducted in January 2015 with the goal of improving the position estimates for the Chinese Deep Space Station Kashi. Previously, the position estimates had been only accurate to ~20 cm, which is insufficient for future Chinese deep space explorations. The experiment design and data reduction are described with special emphasis on the limited frequency ranges of Kashi for bandwidth synthesis. A narrowed multi-band delay search window based on post-fit residuals was utilized to resolve the sub-ambiguities due to the drop of a frequency channel in fringe fit, which saved ~22% of the observations from the affected baseline. Final position estimates of Kashi were obtained from the global solution by using more than 5300 international VLBI sessions from August 1979 to September 2015, and estimates were found to be accurate to about 10, 25, and 20 mm in the X, Y, and Z components. Various statistical tests were run, and the estimates and precisions are believed to be reliable.
