With the wide use of high-resolution remotely sensed imagery, the object-oriented remotely sensed informa- tion classification pattern has been intensively studied. Starting with the definition of object-oriented remo...With the wide use of high-resolution remotely sensed imagery, the object-oriented remotely sensed informa- tion classification pattern has been intensively studied. Starting with the definition of object-oriented remotely sensed information classification pattern and a literature review of related research progress, this paper sums up 4 developing phases of object-oriented classification pattern during the past 20 years. Then, we discuss the three aspects of method- ology in detail, namely remotely sensed imagery segmentation, feature analysis and feature selection, and classification rule generation, through comparing them with remotely sensed information classification method based on per-pixel. At last, this paper presents several points that need to be paid attention to in the future studies on object-oriented RS in- formation classification pattern: 1) developing robust and highly effective image segmentation algorithm for multi-spectral RS imagery; 2) improving the feature-set including edge, spatial-adjacent and temporal characteristics; 3) discussing the classification rule generation classifier based on the decision tree; 4) presenting evaluation methods for classification result by object-oriented classification pattern.展开更多
In order to realize spacecraft autonomy activity duration and complex temporal relations must be taken into consideration. In the space mission planning system, the traditional planners are unable to describe this kno...In order to realize spacecraft autonomy activity duration and complex temporal relations must be taken into consideration. In the space mission planning system, the traditional planners are unable to describe this knowledge, so an object-oriented temporal knowledge representation method is proposed to model every activity as an object to describe the activity's duration, start-time, end-time and the temporal relations with other activities. The layered planning agent architecture is then designed for spacecraft autonomous operation, and the functions of every component are given. A planning algorithm based on the temporal constraint satisfaction is built in detail using this knowledge representation and system architecture. The prototype of Deep Space Mission Autonomous Planning System is implemented. The results show that with the object-oriented temporal knowledge description method, the space mission planning system can be used to describe simultaneous activities, resource and temporal constraints, and produce a complete plan for exploration mission quickly under complex constraints.展开更多
In two dimensions, we study the compressible hydrodynamic flow of liquid crystals with periodic boundary conditions. As shown by Ding et al. （2013）, when the parameter λ→∞ oo, the solutions to the compressible li...In two dimensions, we study the compressible hydrodynamic flow of liquid crystals with periodic boundary conditions. As shown by Ding et al. （2013）, when the parameter λ→∞ oo, the solutions to the compressible liquid crystal system approximate that of the incompressible one. Furthermore, Ding et al. （2013） proved that the regular incompressible limit solution is global in time with small enough initial data. In this paper, we show that the solution to the compressible liquid crystal flow also exists for all time, provided that is sufficiently large and the initial data are almost incompressible.展开更多
基金Under the auspices of the National Natural Science Foundation of China (No. 40301038), Talents Recruitment Foun-dation of Nanjing University
文摘With the wide use of high-resolution remotely sensed imagery, the object-oriented remotely sensed informa- tion classification pattern has been intensively studied. Starting with the definition of object-oriented remotely sensed information classification pattern and a literature review of related research progress, this paper sums up 4 developing phases of object-oriented classification pattern during the past 20 years. Then, we discuss the three aspects of method- ology in detail, namely remotely sensed imagery segmentation, feature analysis and feature selection, and classification rule generation, through comparing them with remotely sensed information classification method based on per-pixel. At last, this paper presents several points that need to be paid attention to in the future studies on object-oriented RS in- formation classification pattern: 1) developing robust and highly effective image segmentation algorithm for multi-spectral RS imagery; 2) improving the feature-set including edge, spatial-adjacent and temporal characteristics; 3) discussing the classification rule generation classifier based on the decision tree; 4) presenting evaluation methods for classification result by object-oriented classification pattern.
文摘In order to realize spacecraft autonomy activity duration and complex temporal relations must be taken into consideration. In the space mission planning system, the traditional planners are unable to describe this knowledge, so an object-oriented temporal knowledge representation method is proposed to model every activity as an object to describe the activity's duration, start-time, end-time and the temporal relations with other activities. The layered planning agent architecture is then designed for spacecraft autonomous operation, and the functions of every component are given. A planning algorithm based on the temporal constraint satisfaction is built in detail using this knowledge representation and system architecture. The prototype of Deep Space Mission Autonomous Planning System is implemented. The results show that with the object-oriented temporal knowledge description method, the space mission planning system can be used to describe simultaneous activities, resource and temporal constraints, and produce a complete plan for exploration mission quickly under complex constraints.
基金supported by National Basic Research Program of China(973 Program)(Grant No.2011CB808002)National Natural Science Foundation of China(Grant Nos.11001085,11071086 and 11128102)+2 种基金the University Special Research Foundation for PhD Program(Grant No.20104407110002)the PhD Programs Foundation of Ministry of Education of China(Grant No.20100172120026)the Fundamental Research Funds for the Central Universities(Grant No.2012ZZ0075)
文摘In two dimensions, we study the compressible hydrodynamic flow of liquid crystals with periodic boundary conditions. As shown by Ding et al. （2013）, when the parameter λ→∞ oo, the solutions to the compressible liquid crystal system approximate that of the incompressible one. Furthermore, Ding et al. （2013） proved that the regular incompressible limit solution is global in time with small enough initial data. In this paper, we show that the solution to the compressible liquid crystal flow also exists for all time, provided that is sufficiently large and the initial data are almost incompressible.
