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Yayın The sectoral sweeper scheme for wireless sensor networks: Adaptive antenna array based sensor node management and location estimation(Kluwer Academic Publishers-Plenum Publishers, 2006-12) Erdoğan, Ayhan; Coşkun, Vedat; Kavak, AdnanWe introduce a novel sensor node management and location estimation method referred as sectoral sweeper (SS) scheme that uses an adaptive antenna array (AAA) at a central node in wireless sensor networks (WSNs). With the SS scheme, the central node can activate or deactivate the nodes in a desired region which is specified by beam direction and beam width of the transmit beam and also by minimum and maximum thresholds (R (min) and R (max)) for the received signal strength indicator (RSSI) of signals received by the nodes. In order to perform a specified task that is associated with a Task_id, two different beams are transmitted, which are task region beam and routing region beam to switch the nodes into active or routing modes. Since our scheme does not require any additional software or hardware for node management and location estimation in sensor nodes, the deficiencies of tiny sensors are effectively eliminated. The proposed scheme is shown to reduce the number of sensing nodes and the amount of data traffic in the network, thus leading to considerable savings in energy consumption and prolonged sensor lifetime.Yayın On the equilibrium of a rigid body suspended by a set of linear springs(John Wiley & Sons, 2000-08) Tokad, YılmazIn this paper an approach is described for determining equilibrium states of a rigid body suspended elastically in space by a set of linear springs. This system is considered as a two-terminal generalized spring with terminal across (translational and rotational velocities, V-G, omega(G)) and terminal through (terminal force and moment, f(G), m(G)) variables. The algorithmic approach used for the solution of six nonlinear and coupled equilibrium equations consists of two major steps. The first step is to assign an initial orientation to the rigid body which is represented by the transformation (rotation) matrix T(theta,n) and reduce the problem to the solution of force equations only through a computer program. This yields the position vector xi of a preselected point G on the rigid body. Although the terminal force f(G) becomes zero at this position, the calculated terminal moment m(G), in general, is not equal to zero. The second step is to try to determine the correct orientation of the rigid body based on an argument that the terminal moment should vanish. The same argument is also used for the solution of force equilibrium equations. These two steps are repeated several times until both f(G) and m(G) vanish simultaneously yielding an equilibrium state (xi,T(theta, n)). Application of the approach is illustrated through various examples. It is observed that, if there are nonstable equilibrium states of the system, then sometimes all possible physical equilibrium states may not be obtained with this approach.Yayın Signals of chaotic behavior in PMMA(Pergamon-Elsevier Science, 2003-07) Hacınlıyan, Avadis Simon; Skarlatos, Yani; Şahin, Gökhan; Akın, Güzin GülsünThe time evolution of the current passing through PMMA polymer thin films under 10 V at 23degreesC (296 K) was sampled at intervals ranging from 1 to 20 s. The data showed chaotic behavior in the context of pinned charge density waves [Phys. Rev. B 41 (1990) 11522]. The resultant time series has been analyzed by means of TISEAN, time series analysis software [The TISEAN package CHAOS 9 (1999) 413]. The analysis has revealed a positive maximal Lyapunov exponent. This is also corroborated by a calculation of the fractal dimension and application of the Kaplan-Yorke conjecture. In the analysis two widely separated time scales have been observed; the first zero crossing of the correlation function at 8380 s and the first marked minimum of the average mutual information at 40 s.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 Usability of mobile voting with NFC technology(Acta Press, 2010) Ok, Kerem; Coşkun, Vedat; Aydın, Mehmet NafizVoting is a method to select one opinion or a person often following discussion, debate or an election campaign. After centuries of paper based voting ballots, electronic voting is used along with various technologies. One of the promising technologies is Near Field Communication (NFC) which allows data transfer between NFC-enabled devices and smart tags within a short distance. In this paper, we have presented a new type of a secure voting system, namely NFC voting, and evaluated the system's usability in a university council election with an executable prototype. Among other findings, we found that NFC voting satisfies electronic voting requirements and further increases the subjective usability of the proposed system.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 parametric approach to construct two-variable positive real impedance functions for the real frequency design of mixed lumped-distributed matching networks(IEEE, 2004) Aksen, Ahmet; Pınarbaşı, Hacı; Yarman, Bekir Sıddık BinboğaIn this paper, a parametric approach to construct two-variable positive real driving point impedance functions characterizing lossless ladder networks with mixed lumped and distributed elements is presented. The proposed approach is based on the generation of two-variable positive real impedance functions from the single variable boundary conditions. Utilizing the proposed parametric construction algorithm, real frequency matching technique is extended to the design of matching networks with mixed lumped and distributed elements. The application of the approach is illustrated by a broadband microwave amplifier design incorporating mixed lumped and distributed type matching networks. The resultant design has been compared with the AWR Microwave Office software simulation.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.Yayın Air interface identification for Software Radio systems(Elsevier GMBH, 2007) Öner, Mustafa Mengüç; Jondral, Friedrich K.Reconfigurable Software Radio (SR) equipment is considered as the next evolutionary step in the mobile communications. One of the most crucial properties of a SR terminal is that it is capable of using a wide range of air interface standards, providing a seamless interoperability between different standards and an enhanced roaming capability, paving way to a more flexible and efficient use of spectral resources. This multimode operation has to be supported by a number of key functionalities, one of which is the air interface identification. A SR terminal, when switched on, has to be able to locate and identify the air interfaces available in the frequency environment, and while connected to a network, it has to monitor the presence of alternative air interfaces to perform interstandard handover if necessary. In our work, we propose exploiting the distinct cyclostationary properties of signals from different air interfaces as features for air interface identification.
