It is important to calculate the reachable domain(RD)of the manned lunar mission to evaluate whether a lunar landing site could be reached by the spacecraft. In this paper, the RD of free return orbits is quickly eval...It is important to calculate the reachable domain(RD)of the manned lunar mission to evaluate whether a lunar landing site could be reached by the spacecraft. In this paper, the RD of free return orbits is quickly evaluated and calculated via the classification and regression neural networks. An efficient databasegeneration method is developed for obtaining eight types of free return orbits and then the RD is defined by the orbit’s inclination and right ascension of ascending node(RAAN) at the perilune. A classify neural network and a regression network are trained respectively. The former is built for classifying the type of the RD, and the latter is built for calculating the inclination and RAAN of the RD. The simulation results show that two neural networks are well trained. The classification model has an accuracy of more than 99% and the mean square error of the regression model is less than 0.01°on the test set. Moreover, a serial strategy is proposed to combine the two surrogate models and a recognition tool is built to evaluate whether a lunar site could be reached. The proposed deep learning method shows the superiority in computation efficiency compared with the traditional double two-body model.展开更多
Two common problems for a typical Power distribution system are voltage collapse & instability. Challenge is to identify the vulnerable nodes and apply the effective corrective actions. This paper presents a proba...Two common problems for a typical Power distribution system are voltage collapse & instability. Challenge is to identify the vulnerable nodes and apply the effective corrective actions. This paper presents a probabilistic fuzzy approach to assess the node status and proposes feeder reconfiguration as a method to address the same. Feeder reconfiguration is altering the topological structures of distribution feeders by changing the open/closed states of the sectionalizing and ties switches. The solution is converge using a probabilistic fuzzy modeled solution, which defines the nodal vulnerability index (VI) as a function of node voltage and node voltage stability index and predicts nodes critical to voltage collapse. The information is further used to plan best combination of feeders from each loop in distribution system to be switched out such that the resulting configuration gives the optimal performance i.e. best voltage profile and minimal kW losses. The proposed method is tested on established radial distribution system and results are presented.展开更多
Nano-materials are the newly emerged materials developed since the end of eighties and the beginning of nineties of last century by a frontier and cross-discipline technology-nanotechnology. Nanomaterial research invo...Nano-materials are the newly emerged materials developed since the end of eighties and the beginning of nineties of last century by a frontier and cross-discipline technology-nanotechnology. Nanomaterial research involves many unknown processes and wonderful phenomena, which can hardly been explained using traditional terminology and standards. To guide and standardize the development of nanomaterials, in the year of 2002, the Ministry of Science and Technology listed the project of developing the "Nanomaterial Standard" as the "Basic Research Program". Meanwhile, the Standardization Administration of China (SAC) also listed the development of "Nanomaterial Standards" in its yearly work program. Through the efforts of the drafting bodies, the work of drafting and developing the standards has been partly completed. Now, 7 national standards on nanomaterials headed by Terminology for nanomterials (GB/T 19619-2004) and etc. have been promulgated by SAC on Sept.29th, 2004 and Dec.27th, 2004 and were implemented since April 1st, 2005. This is the first time China approves and promulgates national standards concerning nanomaterials and it is also the first time in the world that nanomaterials standards are promulgated as the form of national standards. On Feb.28th, 2005, the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) and SAC jointly held a press conference announcing the promulgation of the first batch of national standards on nanomaterials in Beijing.展开更多
基金supported by the National Natural Science Foundation of China (12072365)the Natural Science Foundation of Hunan Province of China (2020JJ4657)。
文摘It is important to calculate the reachable domain(RD)of the manned lunar mission to evaluate whether a lunar landing site could be reached by the spacecraft. In this paper, the RD of free return orbits is quickly evaluated and calculated via the classification and regression neural networks. An efficient databasegeneration method is developed for obtaining eight types of free return orbits and then the RD is defined by the orbit’s inclination and right ascension of ascending node(RAAN) at the perilune. A classify neural network and a regression network are trained respectively. The former is built for classifying the type of the RD, and the latter is built for calculating the inclination and RAAN of the RD. The simulation results show that two neural networks are well trained. The classification model has an accuracy of more than 99% and the mean square error of the regression model is less than 0.01°on the test set. Moreover, a serial strategy is proposed to combine the two surrogate models and a recognition tool is built to evaluate whether a lunar site could be reached. The proposed deep learning method shows the superiority in computation efficiency compared with the traditional double two-body model.
文摘Two common problems for a typical Power distribution system are voltage collapse & instability. Challenge is to identify the vulnerable nodes and apply the effective corrective actions. This paper presents a probabilistic fuzzy approach to assess the node status and proposes feeder reconfiguration as a method to address the same. Feeder reconfiguration is altering the topological structures of distribution feeders by changing the open/closed states of the sectionalizing and ties switches. The solution is converge using a probabilistic fuzzy modeled solution, which defines the nodal vulnerability index (VI) as a function of node voltage and node voltage stability index and predicts nodes critical to voltage collapse. The information is further used to plan best combination of feeders from each loop in distribution system to be switched out such that the resulting configuration gives the optimal performance i.e. best voltage profile and minimal kW losses. The proposed method is tested on established radial distribution system and results are presented.
文摘Nano-materials are the newly emerged materials developed since the end of eighties and the beginning of nineties of last century by a frontier and cross-discipline technology-nanotechnology. Nanomaterial research involves many unknown processes and wonderful phenomena, which can hardly been explained using traditional terminology and standards. To guide and standardize the development of nanomaterials, in the year of 2002, the Ministry of Science and Technology listed the project of developing the "Nanomaterial Standard" as the "Basic Research Program". Meanwhile, the Standardization Administration of China (SAC) also listed the development of "Nanomaterial Standards" in its yearly work program. Through the efforts of the drafting bodies, the work of drafting and developing the standards has been partly completed. Now, 7 national standards on nanomaterials headed by Terminology for nanomterials (GB/T 19619-2004) and etc. have been promulgated by SAC on Sept.29th, 2004 and Dec.27th, 2004 and were implemented since April 1st, 2005. This is the first time China approves and promulgates national standards concerning nanomaterials and it is also the first time in the world that nanomaterials standards are promulgated as the form of national standards. On Feb.28th, 2005, the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) and SAC jointly held a press conference announcing the promulgation of the first batch of national standards on nanomaterials in Beijing.
