Multi-hierarchical fuzzy judgment and nested dominance relation of rough set theory-based environmental risk evaluation for tailings reservoirs

Environmental risk assessment of tailings reservoir assessment system is complex and has many index factors.In order to accurately judge surrounding environmental risks of tailings reservoirs and determinate the corresponding prevention and control work,multi-hierarchical fuzzy judgment and nested dominance relation of rough set theory are implemented to evaluate them and find out the rules of this evaluation system with 14 representative cases.The methods of multi-hierarchical fuzzy evaluation can overall consider each influence factor of risk assessment system and their mutual impact,and the index weight based on the analytic hierarchy process is relatively reasonable.Rough set theory based on dominance relation reduces each index attribute from the top down,largely simplifies the complexity of the original evaluation system,and considers the preferential information in each index.Furthermore,grey correlation theory is applied to analysis of importance of each reducted condition attribute.The results demonstrate the feasibility of the proposed safety evaluation system and the application potential.

System portfolio selection based on GRA method under hesitant fuzzy environment

The hesitant fuzzy set(HFS) is an important tool to deal with uncertain and vague information.In equipment system portfolio selection, the index attribute of the equipment system may not be expressed by precise data;it is usually described by qualitative information and expressed as multiple possible values.We propose a method of equipment system portfolio selection under hesitant fuzzy environment.The hesitant fuzzy element(HFE) is used to describe the index and attribute values of the equipment system.The hesitation degree of HFEs measures the uncertainty of the criterion data of the equipment system.The hesitant fuzzy grey relational analysis(GRA) method is used to evaluate the score of the equipment system, and the improved HFE distance measure is used to fully consider the influence of hesitation degree on the grey correlation degree.Based on the score and hesitation degree of the equipment system,two portfolio selection models of the equipment system and an equipment system portfolio selection case is given to illustrate the application process and effectiveness of the method.

An Advanced Uncertainty Measure Using Fuzzy Soft Sets:Application to Decision-Making Problems

In this paper, uncertainty has been measured in the form of fuzziness which arises due to imprecise boundaries of fuzzy sets. Uncertainty caused due to human’s cognition can be decreased by the use of fuzzy soft sets. There are different approaches to deal with the measurement of uncertainty. The method we proposed uses fuzzified evidence theory to calculate total degree of fuzziness of the parameters. It consists of mainly four parts.The first part is to measure uncertainties of parameters using fuzzy soft sets and then to modulate the uncertainties calculated. Afterward, the appropriate basic probability assignments with respect to each parameter are produced. In the last, we use Dempster’s rule of combination to fuse independent parameters into integrated one. To validate the proposed method, we perform an experiment and compare our outputs with grey relational analysis method. Also,a medical diagnosis application in reference to COVID-19 has been given to show the effectiveness of advanced method by comparing with other method.

A fuzzy trust-based routing model for mitigating the misbehaving nodes in mobile ad hoc networks

Purpose–Security is one of the major challenges in the design and implementation of protocols for mobile ad hoc networks(MANETs).In such systems,the cooperation between nodes is one of the important principles being followed in the current research works to formulate various security protocols.Many existing works assume that mobile nodes will follow prescribed protocols without deviation.However,this is not always the case,because these networks are subjected to a variety of malicious attacks.Since there are various models of attack,trust routing scheme can guarantee security and trust of the network.The purpose of this paper is to propose a novel trusted routing model for mitigating attacks in MANETs.Design/methodology/approach–The proposed model incorporates the concept of trust into the MANETs and applies grey relational analysis theory combined with fuzzy sets to calculate a node’s trust level based on observations from neighbour nodes’trust level,these trust levels are then used in the routing decision-making process.Findings–In order to prove the applicability of the proposed solution,extensive experiments were conducted to evaluate the efficiency of the proposed model,aiming at improving the network interaction quality,malicious node mitigation and enhancements of the system’s security.Originality/value–The proposed solution in this paper is a new approach combining the fundamental basics of fuzzy sets with the grey theory,where establishment of trust relationships among participating nodes is critical in order to enable collaborative optimisation of system metrics.Experimental results indicate that the proposed method is useful for reducing the effects of malicious nodes and for the enhancements of system’s security.