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      • Open Access Article

        1 - A Conflict Resolution Approach using Prioritization Strategy
        Hojjat Emami Kamyar Narimanifar
        In current air traffic control system and especially in free flight method, the resolution of conflicts between different aircrafts is a critical problem. In recent years, conflict detection and resolution problem has been an active and hot research topic in the aviatio More
        In current air traffic control system and especially in free flight method, the resolution of conflicts between different aircrafts is a critical problem. In recent years, conflict detection and resolution problem has been an active and hot research topic in the aviation industry. In this paper, we mapped the aircrafts’ conflict resolution process to graph coloring problem, then we used a prioritization method to solve this problem. Valid and optimal solutions for corresponding graph are equivalent to free conflict flight plans for aircrafts in airspace. The proposed prioritization method is based on some score allocation metrics. After score allocation process, how much the score of an aircraft be higher its priority will be higher and vice versa how much the score of an aircraft be lower its priority will be lower. We implemented and tested our proposed method by different test cases and test results indicate high efficiency of this method. Manuscript profile
      • Open Access Article

        2 - A New Method for Detecting the Number of Coherent Sources in the Presence of Colored Noise
        Shahriar Shirvani Moghaddam Somaye  Jalaei
        In this paper, a new method for determining the number of coherent/correlated signals in the presence of colored noise is proposed which is based on the Eigen Increment Threshold (EIT) method. First, we present a new approach which combines EIT criterion and eigenvalue More
        In this paper, a new method for determining the number of coherent/correlated signals in the presence of colored noise is proposed which is based on the Eigen Increment Threshold (EIT) method. First, we present a new approach which combines EIT criterion and eigenvalue correction. The simulation results show that the new method estimates the number of noncoherent signals in the presence of colored noise with higher detection probability respect to MDL, AIC, EGM and conventional EIT. In addition, to apply the proposed EIT algorithm to detect the number of sources in the case of coherent and/or correlated sources, a spatial smoothing preprocessing is added. In this case, simulation results show 100% detection probability for signal to noise ratios greater than -5dB. Final version of the proposed EIT-based method is a simple and efficient way to increase the detection probability of EIT method in the presence of colored noise considering either coherent/correlated or noncoherent sources. Manuscript profile
      • Open Access Article

        3 - A Robust Statistical Color Edge Detection for Noisy Images
        Mina Alibeigi Niloofar Mozafari Zohre Azimifar Mahnaz Mahmoodian
        Edge detection is a fundamental tool that plays a significant role in image processing, and performance of high-level tasks such as image segmentation and object recognition depends on its efficiency. Therefore, edge detection is one of the well-studied areas in image p More
        Edge detection is a fundamental tool that plays a significant role in image processing, and performance of high-level tasks such as image segmentation and object recognition depends on its efficiency. Therefore, edge detection is one of the well-studied areas in image processing and computer vision. However, it is clear that accurate edge map generation is more difficult when images are corrupted with noise. Moreover, most of edge detection methods have parameters which must be set manually. In recent years different approaches has been used to address these problems. Here we propose a new color edge detector based on a statistical test, which is robust to noise. Also, the parameters of this method will be set automatically based on image content. To show the effectiveness of the proposed method, four state-of-the-art edge detectors are implemented and the results are compared. Experimental results on five of the most well-known edge detection benchmarks show that the proposed method is robust to noise. The performance of our method for lower levels of noise is very comparable to the existing approaches, whose performances highly depend on their parameter tuning stage. However, for higher levels of noise, the observed results significantly highlight the superiority of the proposed method over the existing edge detection methods, both quantitatively and qualitatively. Manuscript profile
      • Open Access Article

        4 - A New Architecture for Intrusion-Tolerant Web Services Based on Design Diversity Techniques
        Sadegh Bejani Mohammad  Abdollahi Azgomi
        Web services are the realization of service-oriented architecture (SOA). Security is an important challenge of SOAP-based Web services. So far, several security techniques and standards based on traditional security mechanisms, such as encryption and digital signature, More
        Web services are the realization of service-oriented architecture (SOA). Security is an important challenge of SOAP-based Web services. So far, several security techniques and standards based on traditional security mechanisms, such as encryption and digital signature, have been proposed to enhance the security of Web services. The aim has been to employ the concepts and techniques of fault-tolerant computing to make Web services more secure, which is called intrusion-tolerance. Intrusion-tolerance means the continuous delivery of services in presence of security attacks, which can be used as a fundamental approach for enhancing the security of Web services. In this paper, we propose a novel architecture for intrusion-tolerant Web services with emphasis on intrusion-tolerance concepts and composite Web service techniques. The proposed architecture, which is called design-diverse intrusion-tolerant Web service (DDITWS), takes the advantages of design diversity techniques. For Web service composition, BPEL4WS is used. Formal modeling and verification of the proposed architecture is performed using colored Petri nets (CPNs) and CPN Tools. We have checked the behavioral properties of the model to ensure its correctness. The reliability and security evaluation of the proposed architecture is also performed using a stochastic Petri net (SPN) model and the SHARPE tool. The results show that the reliability and mean-time-to-security-failure (MTTSF) in the proposed architecture are improved. Manuscript profile