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Background A medical device is any instrument, apparatus, implement, machine, appliance, software, material, which is intended material, to be utilized, either alone or in combination, for medical purpose. These devices should work precisely and the maintenance program of them has also a key role to achieve this goal. Many of the maintenance programs have not considered important functional parameters such as equipment type, risk factors, and expert opinion. Objective The purpose of this study is to present a novel fuzzy method for medical device risk assessment. The obtained values for risk could be used to prioritize maintenance operations by considering allocation budget. Material and methods This experimental study aims to make a new application of Ordered-Weighted Average operator in aggregation of different parameters for calculating Risk Priority Number. This model is a fuzzy multi-criteria decision making approach based on risk maintenance framework for medical device prioritization. Results A limited budget is one of the barrier in medical centers. The suggested framework presents a simple and reliable method to choose the best maintenance strategy for each kind of medical device by considering budget limitation. Based on obtained results from numerical model, defibrillators and surgical suction have respectively the highest and the lowest priority in mentioned example. Conclusion Risk prioritization of medical devices is valuable because the medical centers can prioritize maintenance operations and thereby to establish preference of maintenance strategy. Implementation of our proposed maintenance program has many effective results in medical center budgets. more...

Today, due to the massive amount of information, NoSQL databases are used to compute complex data. These databases are used to store semi-structured and unstructured data for big data management. In this paper, fuzzy queries are executed by users on the information stored in the Neo4j graph database, which show results in defuzzy manner. To evaluate the efficiency of the proposed method, we considered a database of manufactured company, two price and quality fuzzy variable were considered and used to define and execute the fuzzy queries that the results can verify the performance of the proposed method. Additionally, a counselor (who has information about the data) defines fuzzy terms, membership functions, and fuzzy rules table. The most important process in this method is to find the center of gravity in order to defuzzify the final result. So, an algorithm has been implemented for this purpose by C # programming language. The greatest query time is due to find center of gravity. The evaluation results show that the query time increasing by using the proposed approach than the query time by using Cypher language, is acceptable due to the complexity of fuzzy concepts; therefore, the proposed solution will be suitable for using ambiguous and fuzzy queries in large databases. more...

One of the modern paradigms to develop a system is object oriented analysis and design. In this paradigm, there are several objects and each object plays some specific roles. There is a sequence of activities to develop an analysis model. In the first step, we work in developing an initial use case model. Then in the second step, they identify a number of concepts and build a glossary of participating objects. Identifying attributes of objects (and classes) is one of the most important steps in the object-oriented paradigm. This paper proposes a method to identify attributes of objects and verify them. The method is also concerned itself with classifying and eliminating the incorrect attributes of objects. Then the method is evaluated in a large application, a Control Command Police System. After that, several guidelines on attributes of objects, based on the practical experience obtained from the evaluation, are provided. more...

The rapid growth of social networks use has made a great platform to present different services, increasing beneficiary of services and business profit. Therefore considering different levels of member activities in these networks, finding highly active members who can have the influence on the choice and the role of other members of the community is one the most important and challenging issues in recent years. These nodes that usually have a high number of relations with a lot of quality interactions are called influential nodes. There are various types of methods and measures presented to find these nodes. Among all the measures, centrality is the one that identifies various types of influential nodes in a network. Here we define four different factors which affect the strength of a relationship. A fuzzy inference system calculates the strength of each relation, creates a crisp matrix in which the corresponding elements identify the strength of each relation, and using this matrix eigenvector measure calculates the most influential node. Applying our suggested method resulted in choosing a more realistic central node with consideration of the strength of all friendships. more...

The Smart Grid is defined as a large-scale electrical grid that can amalgamate the actions of whole users connected to it — generators, consumers and those that do both. Now, the technologies should lie on the abstract mathematics firmly to model and control the operations. Game theory is a mathematical tool to model systems with multi-agents (rational decision-makers). Game theory models the behavior of independent and rational agents which they want to maximize their profits. To this end, we model the behavior of agents and the possible behaviors profit. In the new system, users are able to generate the required energy from renewable energy sources such as solar panels, electric generators, and so forth. Hence, in these complex systems, we would make the use of the mathematical tools to model the interactions and features between the entities. In this paper, three basic questions will be answered which I) Why cooperation between agents is valuable. II) Which forms of cooperation are forming and III) Why and how game theory can model the cooperation. In the following, we survey a number of Game theory-based applications especially cooperative game theory to solve relevant problems in Smart Grid. Smart grid mainly is divided into three branches including Distributed electricity generation (Micro-grid), Demand Side Management (DSM), and Communications that we will describe the applications of game theory in Micro-grid in detail in the following. more...

Recommender Systems (RS) are turned into remarkable tools in electronics commerce (e-commerce) in a way that they effectively find items which are suitable for user's interests. Techniques such as collaborative filtering and content-based filtering are designed for RS. One of the novel methods to recommend appropriate items is using the Ordered Weighted Averaging (OWA) operators to fuzzify the output of RS [1]. OWA is one of the decision-making methods capable of considering the priorities and mental evaluations of a decision-maker. Furthermore it has the ability to assess the measure of orness and include the computation in final decision. This article aims at presenting methods that have been proposed to combine RS and OWA operators and also at proposing the implementation and development of these two methods in future. more...

Multi agent environment are often complex, while each member of agent community has vision about only a part of the environment. In such environment, information fusion of agent community is vital to attain a better accuracy or quality of information. Agents have different ability and can access to information sources with different degree of credibility. As a result, information which is obtained by agents, should be fused with considering their response credibility. In this research, at first we have introduced a method to obtain agent credibility based upon the opinion of agent community. In the proposed method, we measure the possibility of credibility for each agent. Next, we assume that in response to a query, every agent produces a fuzzy answer set in response to a query. On this assumption, a new fuzzy operator with some desired properties for agent responses fusing with their credibility consideration is proposed. more...

Smart grids are integrating advanced technologies into power grids. The new structure has a profound effect on the entire system. Now, power networks can deploy computing technologies to achieve new level of performance and efficiency. Game theory is a mathematical tool for modeling distributed multi-agent systems. There are game theoretic approaches for studying and solving smart grid issues. Important issues have been studied with game theory include demand side management, load shifting and dynamic energy price. Different authors have used different types of games and payoff functions. In this paper, we categorize most important issues and subjects in both game theory and smart grid. Also, we have a comprehensive review of articles which propose game theoretic approaches in the field of smart grid. more...

Load balancing is one of the most challenging goals in smart grid systems. Obviously, a selfish user's behavior necessitates the use of incentive compatible mechanisms in order to regulate supply and demand. Dynamic pricing is one of the best mechanisms in which the price is being adjusted dynamically such that to make a balance between supply and demand. In the balance, the consumer's demand for energy through financial incentives is adjusted. To determine and announce the appropriate electricity price, there should be a precise forecast for energy usage. In this paper, in order to forecast energy usage two neural networks for each influential factors based on the situation such as weather related or historical loads criteria are developed. Afterwards, the outputs of neural networks are aggregated with the use of Induced Ordered Weighted Operator (IOWA). The argument ordering process is guided by mean absolute percentage error. Also the cuckoo optimization algorithm is applied on artificial neural networks to improve the accuracy of them. The experimental result show that the precision of aggregated load forecasting based upon IOWA operator is improved significantly. more...