The medium-term runoff forecasting provided new information for forecast of medium and long term runoff and optimal hydroelectric power generation.According to the actual runoff and hydropower generating characteristi...The medium-term runoff forecasting provided new information for forecast of medium and long term runoff and optimal hydroelectric power generation.According to the actual runoff and hydropower generating characteristics of Ertan Hydropower Station,we studied the decade runoff quantitatively and grade forecast model based on Global Forecasting System(GFS) precipitation forecast information in wet season,then used the posteriori runoff transition probability and measurable probability of runoff forecast to research the uncertain runoff description based on runoff forecast;finally on the basis of the runoff description and the grading forecast accuracy of GFS-based next 10 days'total forecast precipitation,we studied the uncertain optimal operating model of Ertan Hydropower Station considering runoff forecast.The results showed that the runoff forecast considering GFS forecast precipitation and uncertainty has significantly improved the existing runoff description and operating optimization model,and obviously raised the hydropower generation efficiency of Ertan Reservoir.展开更多
With the development of researches on the classification quality of remote sensing images, researchers thought that uncertainty is the main factor that influences classification quality. This study puts forward an app...With the development of researches on the classification quality of remote sensing images, researchers thought that uncertainty is the main factor that influences classification quality. This study puts forward an approach to uncertainty repre- sentation, which is developed from two aspects： formalized description and comprehensive evaluation. First, we complete the classification using fuzzy surveillance approach, taking it as a formalized description of classification uncertainty. Then we in- troduce a hybrid entropy model for classification uncertainty evaluation, which can meet the requirement of comprehensive reflection of several uncertainties, while constructing the evaluation index from pixel scale with the full consideration of the different contribution to the error rate of each pixel. Finally, an application example will be studied to examine the new method. The result shows that the evaluation results fully reflect the classification quality, when compared with the conventional evaluation method which constructs models from unitary uncertainty and category scale.展开更多
Ontologies are widely used in modeling the real world for the purpose of information sharing and reasoning. Traditional ontologies contain only concepts and relations that describe asserted facts about the world. Mode...Ontologies are widely used in modeling the real world for the purpose of information sharing and reasoning. Traditional ontologies contain only concepts and relations that describe asserted facts about the world. Modeling in a dynamic world requires taking into consideration the uncertainty that may arise in the domain. In this paper, the concept of soft sets initiated by Molodtsov and the concept of rough sets introduced by Pawlack are used to define a way of instantiating ontologies of vague domains. We define ontological algebraic operations and their properties while taking into consideration the uncertain nature of domains. We show that, by doing so, intra ontological operations and their properties are preserved and formalized as operations in a vague set of objects and can be proved algebraically.展开更多
The indetermination of direction relation is a hot topic for fuzzy GIS researchers. The existing models only study the effects of indetermination of spatial objects,but ignore the uncertainty of direction reference fr...The indetermination of direction relation is a hot topic for fuzzy GIS researchers. The existing models only study the effects of indetermination of spatial objects,but ignore the uncertainty of direction reference framework. In this paper,first a for-malized representation model of indeterminate spatial objects is designed based on quadruple (x,y,A,μ),then a fuzzy direction reference framework is constructed by revising the cone method,in which the partitions of direction tiles are smooth and continuous,and two neighboring sections are overlapped in the transitional zones with fuzzy method. Grounded on these,a fuzzy description model for indeterminate direction relation is proposed in which the uncertainty of all three parts (source object,reference object and reference frame) is taken into account simultaneously. In the end,case studies are implemented to test the rationality and validity of the model.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.50579095,51079015)
文摘The medium-term runoff forecasting provided new information for forecast of medium and long term runoff and optimal hydroelectric power generation.According to the actual runoff and hydropower generating characteristics of Ertan Hydropower Station,we studied the decade runoff quantitatively and grade forecast model based on Global Forecasting System(GFS) precipitation forecast information in wet season,then used the posteriori runoff transition probability and measurable probability of runoff forecast to research the uncertain runoff description based on runoff forecast;finally on the basis of the runoff description and the grading forecast accuracy of GFS-based next 10 days'total forecast precipitation,we studied the uncertain optimal operating model of Ertan Hydropower Station considering runoff forecast.The results showed that the runoff forecast considering GFS forecast precipitation and uncertainty has significantly improved the existing runoff description and operating optimization model,and obviously raised the hydropower generation efficiency of Ertan Reservoir.
基金Supported by the Provincial Science Research Program in Hubei Province of China (No. ETZ2007A03)
文摘With the development of researches on the classification quality of remote sensing images, researchers thought that uncertainty is the main factor that influences classification quality. This study puts forward an approach to uncertainty repre- sentation, which is developed from two aspects： formalized description and comprehensive evaluation. First, we complete the classification using fuzzy surveillance approach, taking it as a formalized description of classification uncertainty. Then we in- troduce a hybrid entropy model for classification uncertainty evaluation, which can meet the requirement of comprehensive reflection of several uncertainties, while constructing the evaluation index from pixel scale with the full consideration of the different contribution to the error rate of each pixel. Finally, an application example will be studied to examine the new method. The result shows that the evaluation results fully reflect the classification quality, when compared with the conventional evaluation method which constructs models from unitary uncertainty and category scale.
文摘Ontologies are widely used in modeling the real world for the purpose of information sharing and reasoning. Traditional ontologies contain only concepts and relations that describe asserted facts about the world. Modeling in a dynamic world requires taking into consideration the uncertainty that may arise in the domain. In this paper, the concept of soft sets initiated by Molodtsov and the concept of rough sets introduced by Pawlack are used to define a way of instantiating ontologies of vague domains. We define ontological algebraic operations and their properties while taking into consideration the uncertain nature of domains. We show that, by doing so, intra ontological operations and their properties are preserved and formalized as operations in a vague set of objects and can be proved algebraically.
基金the National Natural Science Foundation of China (Grant Nos. 40701143, 40701145 and 40571127)
文摘The indetermination of direction relation is a hot topic for fuzzy GIS researchers. The existing models only study the effects of indetermination of spatial objects,but ignore the uncertainty of direction reference framework. In this paper,first a for-malized representation model of indeterminate spatial objects is designed based on quadruple (x,y,A,μ),then a fuzzy direction reference framework is constructed by revising the cone method,in which the partitions of direction tiles are smooth and continuous,and two neighboring sections are overlapped in the transitional zones with fuzzy method. Grounded on these,a fuzzy description model for indeterminate direction relation is proposed in which the uncertainty of all three parts (source object,reference object and reference frame) is taken into account simultaneously. In the end,case studies are implemented to test the rationality and validity of the model.
