• OpenAccess
    • List of Articles Aref Safari

      • Open Access Article

        1 - Uncertain Fuzzy Time Series: Technical and Mathematical Review
        Aref Safari
        Time series consists of a sequence of observations, measured at moments in time, sorted chronologically, and evenly spaced from each other, so the data are usually dependent on each other. Uncertainty is the consequence of imperfection of knowledge about a state or a pr More
        Time series consists of a sequence of observations, measured at moments in time, sorted chronologically, and evenly spaced from each other, so the data are usually dependent on each other. Uncertainty is the consequence of imperfection of knowledge about a state or a process. The time series is an important class of time-based data objects and it can be easily obtained from scientific and financial applications. Main carrier of time series forecasting is which constitutes the level of uncertainty human knowledge, with its intrinsic ambiguity and vagueness in complex and non-stationary criteria. In this study, a comprehensive revision on the existing time series pattern analysis research is given. They are generally categorized into representation and indexing, similarity measure, uncertainty modeling, visualization and mining. Various Fuzzy Time Series (FTS) models have been proposed in scientific literature during the past decades or so. Among the most accurate FTS models found in literature are the high order models. However, three fundamental issues need to be resolved with regards to the high order models. The primary objective of this paper is to serve as a glossary for interested researchers to have an overall depiction on the current time series prediction and fuzzy time-series models development. Manuscript profile
      • Open Access Article

        2 - An Interval Type-2 Fuzzy-Markov Model for Prediction of Urban Air Pollution
        Aref Safari Rahil Hosseini Mahdi Mazinani
        Prediction is a very important problem that appears in many disciplines. Better weather forecasts can save lives in the event of a catastrophic hurricane; better financial forecasts can improve the return on an investment. The increasing rate of industrial development a More
        Prediction is a very important problem that appears in many disciplines. Better weather forecasts can save lives in the event of a catastrophic hurricane; better financial forecasts can improve the return on an investment. The increasing rate of industrial development and urbanization, especially in developing countries, has led to increased levels of air pollution along with increased concern about air pollution effect on human health. This has taken about a diversity of strategies for air quality management, prediction and pollution control. Today’s applications of fuzzy systems are emerging in uncertain environments such as air quality assessments. A fuzzy system that accounts for all of the uncertainties that are present, namely, rule uncertainties due to training with noisy data and measurement uncertainties due to noisy measurements that are used during actual forecasting. The performance results on real data set show the superiority of the fuzzy-markov model in the prediction process with an average accuracy of 94.79% compared to other related works. These results are promising for early prediction of the natural disasters and prevention of its side effects Manuscript profile
      • Open Access Article

        3 - A Technical Review on Unsupervised Learning of Graph and Hypergraph Pattern Analysis
        Aref Safari
        Graph and hypergraph matching are fundamental problems in pattern analysis problems. They are applied to various tasks requiring 2D and 3D feature matching, such as image alignment, 3D reconstruction, and object or action recognition. Graph pattern analysis considers pa More
        Graph and hypergraph matching are fundamental problems in pattern analysis problems. They are applied to various tasks requiring 2D and 3D feature matching, such as image alignment, 3D reconstruction, and object or action recognition. Graph pattern analysis considers pairwise constraints that usually encode geometric and appearance associations between local features. On the other hand, hypergraph matching incorporates higher-order relations computed over sets of features, which could capture both geometric and appearance information. Therefore, using higher-order constraints enables matching that is more robust (or even invariant) to changes in scale, non-rigid deformations, and outliers. Many objects or other entities such as gesture recognition and human activities in the spatiotemporal domain can be signified by graphs with local information on nodes and more global information on edges or hyperedges. In this research, and essential review have been done on the unsupervised methods to explore and communicate meta-analytic data and results with a large number of novel graphs proposed quite recently. Manuscript profile