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Yayın Improving the calibration time of traffic simulation models using parallel computing technique(Institute of Electrical and Electronics Engineers Inc., 2019-06) Dadashzadeh, Nima; Ergün, Murat; Kesten, Ali Sercan; Zura, MarijanThe calibration procedure for traffic simulation models can be a very time-consuming process in the case of a large-scale and complex network. In the application of Evolutionary Algorithms (EA) such as Genetic Algorithms (GA) and Particle Swarm Optimization (PSO) for calibration of traffic simulation models, objective function evaluation is the most time-consuming step in such calibration problems, because EA has to run a traffic simulation and calculate its corresponding objective function value once for each set of parameters. The main contribution of this study has been to develop a quick calibration procedure for the parameters of driving behavior models using EA and parallel computing techniques (PCTs). The proposed method was coded and implemented in a microscopic traffic simulation software. Two scenarios with/without PCT were analyzed using the developed methodology. The results of scenario analysis show that using an integrated calibration and PCT can reduce the total computational time of the optimization process significantly-in our experiments by 50%-and improve the optimization algorithm's performance in a complex optimization problem. The proposed method is useful for overcoming the limitation of computational time of the existing calibration methods and can be applied to various EAs and traffic simulation software.Yayın Detection of DHCP starvation attacks in software defined networks: a case study(IEEE, 2018-12-06) Toprak, Cansu; Türker, Cem; Tüysüz Erman, AyşegülSoftware Defined Networking (SDN) is an emerging concept that maintains and analyzes the network status with its centralized architecture. This facility ensures network operators to monitor and manage the network elements with custom applications running on a single or multiple controllers. In this paper, we show that network security issues such as threat detection can easily be solved by using SDN due to its programmable nature. This paper specifically presents a case study that addresses a solution for detection of DHCP starvation attacks in an SDN, which is one of the most common network security problems that may disable the whole network operations.Yayın Modeling and simulation support to the defense planning process(Sage Publications Inc, 2017-04-01) Çayırcı, Erdal; Özçakır, LütfüDefense planning is a crucial part of the defense process. It identifies the capabilities required for the future defense environment, analyzes the capability shortfalls, prioritizes them, and provides the fundamental inputs for their development. Modeling and simulation may significantly contribute to the success of defense planning. However, neither the theory nor the tools are mature enough to fulfill the defense planning requirements. Various types of simulation tools, such as static, dynamic, deterministic, stochastic, closed, discrete, continuous, and symbiotic, in multiple levels of resolution and fidelity are needed to support the different stages and phases. The verification and validation of the models and the analysis of the input and output data are critical. Yet another challenge is that the uncertainties related to the contemporary defense scenarios are mostly not in aleatory but in the epistemic domain. In this paper, we briefly present a new computer-assisted defense planning process. Then, we introduce the service-oriented cloud approach for the modeling and simulation support to the process.Yayın A new software tool to model measured RF-data with optimum circuit topology(IEEE, 2004) Yarman, Bekir Sıddık Binboğa; Kılınç, Ali; Aksen, AhmetIn this paper a new S/W tool is presented to model measured RF data employing immitance interpolation techniques. This S/W tool also employs a recently developed sub-routine, which generates circuit models with least number of circuit elements by means of a novel numerical approach. Furthermore, an analytic procedure is introduced and implemented within the new S/W package to select proper sample-points subject to interpolation which in turn controls the interpolation error in the "near min-max sense" or the so-called "Chebyshev Sense". Hence, the optimum circuit topology for the given data is constructed. An example is presented to exhibit the utilization of the new tool. This new S/W package may be utilized as the front end to the commercially available Design and Analysis Packages such as ANSOFT, EAGELWARE etc.
