With the continuous development of society,the urban space has already met the basic functional needs of the people.As the crystallization of the ideology of mankind and the social development,the urban space exerts a...With the continuous development of society,the urban space has already met the basic functional needs of the people.As the crystallization of the ideology of mankind and the social development,the urban space exerts an effect on the people on both the material level and the spiritual level.The urban space inherits the urban culture and influences people’s feelings,and the proper narrative space can meet the increasing emotional needs.This paper analyzes the three formative factors of the urban narrative space—the temporal factor,the spatial factor and the diversified event factor,showing the readers a clearer narrative space and laying foundation for the further study on narrative space theory.展开更多
Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment,it is prone to the partial loss of control effectiveness(PLCE)fault.An adaptive fault-tolerant co...Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment,it is prone to the partial loss of control effectiveness(PLCE)fault.An adaptive fault-tolerant control algorithm is designed for a space robot system with the uncertain parameters and the PLCE actuator faults.The mathematical model of the system is established based on the Lagrange method,and the PLCE actuator fault is described as an effectiveness factor.The lower bound of the effectiveness factors and the upper bound of the uncertain parameters are estimated by an adaptive strategy,and the estimated value is fed back to the control algorithm.Compared with the traditional fault-tolerant algorithms,the proposed algorithm does not need to predetermine the lower bound of the effectiveness factor,hence it is more in line with the actual engineering application.It is proved that the algorithm can guarantee the stability of the closed-loop system based on the Lyapunov function method.The numerical simulation results show that the proposed algorithm can not only compensate for the uncertain parameters,but also can tolerate the PLCE actuator faults effectively,which verifies the effectiveness and superiority of the control scheme.展开更多
Oil-paper compound insulation has been widely used in power transformers for quite a long time because of its good performances. The insulation gradually degrades under combined thermal, electrical and chemical stress...Oil-paper compound insulation has been widely used in power transformers for quite a long time because of its good performances. The insulation gradually degrades under combined thermal, electrical and chemical stresses during routine operations, mainly because of space charges inside. This work investigated the space charge characteristics in oil-paper insulation under oil aging circumstance. New trans- former oil samples are thermally aged to obtain different aging states, and their physical and chemical properties are analyzed. New Kraft papers are dried in vacuum and fully immersed in these different aged oil samples, and three kinds of oil-paper samples are obtained. We use the pulsed electro-acoustic (PEA) method to measure space charge under both DC voltage-on and voltage-off conditions at room temperature. The effect of oil aging state on characteristics of space charge injection, accumulation, and decay is analyzed and discussed. The results show that comparing with the DC voltage-off condition, more charges are injected into samples at the interface of electrode and dielectric when DC voltage is on. When the oil-aged state gets worse, more charges are induced at both cathode and anode, more space charges are accumulated in the bulk, the area of negative charges is larger, and local electric field is distorted more seriously. Moreover, for the voltage-off condition, aged oil is good for space charge decay, and trapped positive space charges decay faster than trapped negative charges.展开更多
科学评估地下空间开发需求潜力是缓解城市化问题和合理拓展有限区域的重要基础工作。目前地下空间评价中的社会经济数据多来自于传统官方文件,其全面完整性和时空精度并不理想;此外主客观赋权方法的使用,一定程度上存在主观性强和受数...科学评估地下空间开发需求潜力是缓解城市化问题和合理拓展有限区域的重要基础工作。目前地下空间评价中的社会经济数据多来自于传统官方文件,其全面完整性和时空精度并不理想;此外主客观赋权方法的使用,一定程度上存在主观性强和受数据干扰等不足。文章以多源大数据支持的指标体系为基础,构建熵权-随机森林耦合的地下空间需求评价模型。该模型基于熵权法确定负样本,将总样本和指标因子导入随机森林算法中,挖掘社会经济指标与现有地下设施间的复杂非线性关系。研究表明,经过网格搜索调优后的模型AUC(area under curve)精度达到0.979,其中77.45%的现有设施落入评价的高需求区内,证明所采用模型有较强的准确性和可靠性,其精细化评价结果可为今后地下建设选址提供更符合实际的借鉴。展开更多
基金the staged achievement of the national natural sciences funded program-Quantitative Study on the Historical Urban Narrative Environment System(51178465)
文摘With the continuous development of society,the urban space has already met the basic functional needs of the people.As the crystallization of the ideology of mankind and the social development,the urban space exerts an effect on the people on both the material level and the spiritual level.The urban space inherits the urban culture and influences people’s feelings,and the proper narrative space can meet the increasing emotional needs.This paper analyzes the three formative factors of the urban narrative space—the temporal factor,the spatial factor and the diversified event factor,showing the readers a clearer narrative space and laying foundation for the further study on narrative space theory.
基金Supported by Siberian Branch of RASEducation and Science Ministry of Russian Federation (No.01-27-SSRT, FSTP "Astron- omy", Leading scientific school 00-15-96 710/SS-477.2003.2)RFBR (02-02-39030, 03-02-16591, 03-02-16229, 03-07-90087, 03-02-3102)RFBR-SFNS (02-02-39030)Integration with the Universities: state contract (No. 10208/1173)the China- Russia Joint Research Center on Space Weather, Chinese Academy of Sciences
文摘In this paper, the possibility and some results of radioheliographic study of space weather solar factors are shortly described.
基金supported by the National Natural Science Foundation of China(11372073,11072061)
文摘Since the joint actuator of the space robot executes the control instructions frequently in the harsh space environment,it is prone to the partial loss of control effectiveness(PLCE)fault.An adaptive fault-tolerant control algorithm is designed for a space robot system with the uncertain parameters and the PLCE actuator faults.The mathematical model of the system is established based on the Lagrange method,and the PLCE actuator fault is described as an effectiveness factor.The lower bound of the effectiveness factors and the upper bound of the uncertain parameters are estimated by an adaptive strategy,and the estimated value is fed back to the control algorithm.Compared with the traditional fault-tolerant algorithms,the proposed algorithm does not need to predetermine the lower bound of the effectiveness factor,hence it is more in line with the actual engineering application.It is proved that the algorithm can guarantee the stability of the closed-loop system based on the Lyapunov function method.The numerical simulation results show that the proposed algorithm can not only compensate for the uncertain parameters,but also can tolerate the PLCE actuator faults effectively,which verifies the effectiveness and superiority of the control scheme.
基金Project supported by China National Fund for Distinguished Young Scientists (51125029)National High-tech Research and Development Program of China (863 Program) (2007AA04Z411)
文摘Oil-paper compound insulation has been widely used in power transformers for quite a long time because of its good performances. The insulation gradually degrades under combined thermal, electrical and chemical stresses during routine operations, mainly because of space charges inside. This work investigated the space charge characteristics in oil-paper insulation under oil aging circumstance. New trans- former oil samples are thermally aged to obtain different aging states, and their physical and chemical properties are analyzed. New Kraft papers are dried in vacuum and fully immersed in these different aged oil samples, and three kinds of oil-paper samples are obtained. We use the pulsed electro-acoustic (PEA) method to measure space charge under both DC voltage-on and voltage-off conditions at room temperature. The effect of oil aging state on characteristics of space charge injection, accumulation, and decay is analyzed and discussed. The results show that comparing with the DC voltage-off condition, more charges are injected into samples at the interface of electrode and dielectric when DC voltage is on. When the oil-aged state gets worse, more charges are induced at both cathode and anode, more space charges are accumulated in the bulk, the area of negative charges is larger, and local electric field is distorted more seriously. Moreover, for the voltage-off condition, aged oil is good for space charge decay, and trapped positive space charges decay faster than trapped negative charges.
文摘科学评估地下空间开发需求潜力是缓解城市化问题和合理拓展有限区域的重要基础工作。目前地下空间评价中的社会经济数据多来自于传统官方文件,其全面完整性和时空精度并不理想;此外主客观赋权方法的使用,一定程度上存在主观性强和受数据干扰等不足。文章以多源大数据支持的指标体系为基础,构建熵权-随机森林耦合的地下空间需求评价模型。该模型基于熵权法确定负样本,将总样本和指标因子导入随机森林算法中,挖掘社会经济指标与现有地下设施间的复杂非线性关系。研究表明,经过网格搜索调优后的模型AUC(area under curve)精度达到0.979,其中77.45%的现有设施落入评价的高需求区内,证明所采用模型有较强的准确性和可靠性,其精细化评价结果可为今后地下建设选址提供更符合实际的借鉴。
