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Yayın Numerical modelling of energy dissipative steel cushions(Korean Soc Steel Constructiın-KSSC, 2019-08) Güllü, Ahmet; Smyrou, Eleni; Khajehdehi, Arastoo; Özkaynak, Hasan; Bal, İhsan Engin; Yüksel, Ercan; Karadoğan, Hüseyin FarukEnergy dissipative steel cushions (EDSCs) are simple units that can be used to join structural members. They can absorb a substantial amount of seismic energy due to their geometric shapes and the ductile behavior of mild steel. Large deformation capability and stable hysteretic behavior were obtained in monotonic and cyclic tests of EDSCs in the framework of the SAFECLADDING project. Discrete numerical modeling strategies were applied to reproduce the experimental results. The first and second models comprise two-dimensional shell elements and one-dimensional flexural frame elements, respectively. The uncertain points in the preparation of the models included the mesh density, representation of the material properties, and interaction between contacting surfaces. A zero-length nonlinear link element was used in the third attempt in the numerical modeling. Parameters are recommended for the Ramberg-Osgood and bilinear models. The obtained results indicate that all of the numerical models can reproduce the response, and the stiffness, strength, and unloading and reloading curves were fitted accurately.Yayın An automatic calibration procedure of driving behaviour parameters in the presence of high bus volume(Faculty of Transport and Traffic Engineering, 2019-11) Dadashzadeh, Nima; Ergün, Murat; Kesten, Ali Sercan; Zura, MarijanMost of the microscopic traffic simulation programs used today incorporate car-following and lane-change models to simulate driving behaviour across a given area. The main goal of this study has been to develop an automatic calibration process for the parameters of driving behaviour models using metaheuristic algorithms. Genetic Algorithm (GA), Particle Swarm Optimization (PSO), and a combination of GA and PSO (i.e. hybrid GAPSO and hybrid PSOGA) were used during the optimization stage. In order to verify our proposed methodology, a suitable study area with high bus volume on-ramp from the 0-1 Highway in Istanbul has been modelled in VISSIM. Traffic data have been gathered through detectors. The calibration procedure has been coded using MATLAB and implemented via the VISSIM-MATLAB COM interface. Using the proposed methodology, the results of the calibrated model showed that hybrid GAPSO and hybrid PSOGA techniques outperformed the GA-only and PSO-only techniques during the calibration process. Thus, both are recommended for use in the calibration of microsimulation traffic models, rather than GA-only and PSO-only techniques.Yayın Analytical and numerical aspects of the dissipative nonlinear Schrödinger equation(Işık University Press, 2016-02-15) Bayındır, CihanIn this paper various analytical and numerical aspects of the dissipative nonlinear Schrodinger equation (d-NLS equation) are discussed. Decaying solitary wave type solutions derived by Demiray is reviewed and a new approximate solitary wave type solution of the d-NLS equation is introduced in order to make comparisons. Also a split-step Fourier scheme is proposed for numerical solution of the d-NLS equation and the analytical solutions are compared with the numerical results.Yayın Rogue wavefunctions due to noisy quantum tunneling potentials(Işık University Press, 2017-02-02) Bayındır, CihanIn this paper, we study the effects of white-noised potentials on nonlinear quantum tunneling. We use a split-step scheme to numerically solve the nonlinear Schrodinger equation (NLSE) with a tunneling potential. We consider three different types of potentials, namely; the single rectangular barrier, double rectangular barrier, and triangular barrier. For all these three cases, we show that white-noise given to potentials do not trigger modulation instability for tunneling of the sech type soliton solutions of the NLSE. However, white-noised potentials trigger modulation instability for tunneling of the sinusoidal wavefunctions; thus, such a wavefield turns into a chaotic one with many apparent peaks. We argue that peaks of such a field may be in the form of rational rogue wave solutions of the NLSE. Our results can be used to examine the effects of noise on quantum tunneling. Since a rogue wavefunction means a higher probability of the tunneling particle to be at a given (x,t) coordinate, our results may also be used for developing the quantum science and technology with many possible applications including but are not limited to increasing the resolution and efficiency of scanning tunneling microscopes, enhancing proton tunneling for DNA mutation and enhancing superconducting properties of junctions.Yayın Compressive split-step Fourier method(Işık University Press, 2015-02-09) Bayındır, CihanIn this paper an approach for decreasing the computational effort required for the split-step Fourier method (SSFM) is introduced. It is shown that using the sparsity property of the simulated signals, the compressive sampling algorithm can be used as a very efficient tool for the split-step spectral simulations of various phenomena which can be modeled by using differential equations. The proposed method depends on the idea of using a smaller number of spectral components compared to the classical split-step Fourier method with a high number of components. After performing the time integration with a smaller number of spectral components and using the compressive sampling technique with l(1) minimization, it is shown that the sparse signal can be reconstructed with a significantly better efficiency compared to the classical split-step Fourier method. Proposed method can be named as compressive split-step Fourier method (CSSFM). For testing of the proposed method the Nonlinear Schrodinger Equation and its one-soliton and two-soliton solutions are considered.
