Papers by Keyword: Rough Set Theory (RST)

Abstract: Rough Set Theory is a mathematic tool which mainly deals with the uncertain knowledge. In this paper a new comprehensive evaluation model of low carbon economy based on rough set is formed. At last, the results of comprehensive evaluation of low carbon economy of 6 provinces based on this model are obtained which show this method is effective and feasible.

Abstract: Under the saline soil environment in the western area of Jilin Province, the concrete durability is affected by a lot of factors, which include wet-dry cycles, freeze-thaw cycles, wet-dry and freeze-thaw cycles, salt soaking time, salts concentration, fly-ash content, air content. These factors impact on the durability of concrete is uncertain, and there may be a problem of duplicate action, with some roughness characteristics. In this article, the rough set theory is used to analyze the degree that these seven factors affect the concrete durability, and to calculate weights. In this article, the loss rate of dynamic elasticity modulus is looked as the evaluation index of concrete durability. The results show that: the importance degrees of 7 factors influencing the loss rate of concrete dynamic elasticity modulus in order are: wet-dry and freeze-thaw cycles > wet-dry cycle > freeze-thaw cycles > multiple salts concentration > air content > long-term soak > fly-ash content.

Abstract: According to the communication equipment fault characteristics of complexity, hierarchy, relevance, delay and uncertainty, the method of extracting diagnosis rules based on rough set is presented in order to obtain diagnostic decision rules with good adaptability and maximum matching capabilities. This method can process a large amount of fault data and it can reduce both attribute and attribute value.4 evaluations are selected to evaluate the effectiveness and reasonableness of decision rules, and finally core value table of decision rules which has a certain ability to adapt. Example shows that this method can remove noise in fault diagnosis sample, reduce the computation and improve the efficiency of diagnosis effectively.

Abstract: An algorithm of uncertain reasoning which more than one result of a new object can be obtained according to the known knowledge is an important part of an expert system. A new object is an especial decision rule which has only a predecessor. In order to resolve the problem that the differences of attributes’ importance in the new object are not considered in traditional methods of uncertain reasoning, a new uncertain reasoning algorithm based on the rules set which is obtained on the basis of the rough set theory is proposed. In the algorithm, both subjective factors and objective factors in the process of reasoning are considered, and the proportion of subjective factors to objective factors can be controlled by users. So the algorithm is better than the tradition method in flexibility and practicability.

Abstract: There are various evaluation indicators in command information system. It is important to determine the weight of each indicator because it has a direct impact on the final result for evaluation and decision making. The reasonable and accurate attribute weight is helpful to ascertain the status or effect on the policy decision. With analyzing the deficiency of attribute weighting algorithms based on the rough sets theory, the new attribute weight algorithm is proposed in the paper. The proposed algorithm considers objective weight and subjective weight. The objective weight includes three factors, named as the importance of the attribute itself, the increment of mutual information, and its own information entropy. The subjective weight is obtained by the experts with prior knowledge in the field. Experiment results prove that the new method not only overcomes the deficiency of the existing weight methods, but also is more in line with the actual situation.

Abstract: The paper discusses general theoretical and practical aspects of the emerging probabilistic and non-probabilistic approaches for uncertainty treatment in finite element analysis. Based on rough set theory, a new methodology for structural reliability computation is presented. The uncertain parameters of structures are expressed by rough variables. The structure reliability index is computed by rough function and metric. It is valid, and efficient in physics and geometry. Examples of practical application are given.

Abstract: The photovoltaic power generation system needed to be work at the maximum power point (MPP) to get the maximum efficiency. As the MPP can be influenced by environment condition, such as temperature and irradiation, it is necessary to optimize and control the PV system operation process. In this paper, a rough Fuzzy-PID control strategy is proposed to adjusting the PV operation to make the system working efficiency. Rough Fuzzy-PID control strategy is best in dealing with time-varying and non-linear system, it is much suitable for solving the MPPT of photovoltaic system through switching pulse generation to DC/DC buck converter. These control systems are modeled and simulated in Matlab/Simulink environment.

Abstract: As a new soft computing method, rough set theory can deal with imprecise, inconsistent, incomplete problems, which is due to the maturity mathematical basis. Considering the environmental factors, the forecast model of grid-connected PV system based on rough sets theory was established, which has been tested and verified on the 5.6kW grid-connected PV system in Beijing Institute of Architectural Engineering. Compared the forecasting result with acture operation results of the week, month, season and year generation, it shows that former is more correct and accuracy. So the research proved that the forecasting model of rough set is practical.

Abstract: The current proposed technologies for fault diagnosis of power system were investigated, including expert system, artificial neural network, optimization methods, and rough set theory. The applicability and characteristics of these technologies for power system fault diagnosis were briefly analyzed and also. The existing flaws and improvements are given. Finally, the recently research status were reviewed and discussed, the key technology issues on and main development trends of the issues are pointed out to motivate the developments.

Abstract: In view of some problems existing in smart grid comprehensive evaluation, such as subjectively determined weight, and the evaluation results strong dependence on the index weight, rough set theory is introduced into this paper because of its objective characteristics in handling multi-attribute decision problems, which can also avoid determining the index weight and data discretional processes. Firstly, the sorting method based on rough sets is improved to overcome the shortages of existing methods, and then the improved sorting method is used in the smart grid evaluation process. Comprehensive evaluation results are shown by examples, with comparison and analysis to other sort method. It shows that the proposed method is reasonable and practical.