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https://hdl.handle.net/20.500.12587/18125

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Symbol detection using the differential evolution algorithm in MIMO-OFDM systems
(Tubitak Scientific & Technological Research Council Turkey, 2013) Seyman, Muhammet Nuri; Taşpınar, Necmi
Channel estimation and symbol detection in multiple-input and multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) systems are essential tasks. Although the maximum likelihood (ML) detector reveals excellent performance for symbol detection, the computational complexity of this algorithm is extremely high in systems with more transmitter antennas and high-order constellation size. In this paper, we propose the differential evolution (DE) algorithm in order to reduce the search space of the ML detector and the computational complexity of symbol detection in MIMO-OFDM systems. The DE algorithm is also compared to some heuristic approaches, such as the genetic algorithm and particle swarm optimization. According to the simulation results, the DE has the advantage of significantly less complexity and is closer to the optimal solution.
Partial Range Completeness of Case Eigenfunctions and Numerical Solution of Singular Integral Equations of Particle Transport Problems
(TAYLOR & FRANCIS INC, 2020) Sahni, D. C.; Tureci, R. G.; Bozkir, A. Z.
We study numerical solution of Singular Integral Equations (SIE) of particle transport theory. We convert them into matrix equations by standard discretization process. It is found that the matrices are highly ill-conditioned and can be solved by Singular Value Decomposition (SVD) method. One expects that matrices resulting from expansions over Partial Range will not be ill-conditioned. We find this is not true though their ill-conditioning is an order of magnitude less than those of full or half range. Reasons for this phenomenon are explained.
Half-space albedo problem for Inonu, linear and quadratic anisotropic scattering
(Korean Nuclear Soc, 2020) Tureci, R. G.
This study is concerned with the investigation of the half-space albedo problem for "Inonu-linearquadratic anisotropic scattering" by the usage of Modified FN method. The method is based on Case's method. Therefore, Case's eigenfunctions and its orthogonality properties are derived for anisotropic scattering of interest. Albedo values are calculated for various linear, quadratic and inonu anisotropic scattering coefficients and tabulated in Tables. (C) 2019 Korean Nuclear Society, Published by Elsevier Korea LLC.
Modified F-N solution of the neutron transport equation for the Milne problem with FBIS kernel
(Indian Assoc Cultivation Science, 2019) Ersoy, A.; Tureci, G.; Senyigit, M.; Gulecyuz, M. C.
The solution of the Milne problem is studied by one-speed neutron transport equation in plane geometry with Inonu's scattering kernel, which is known as a linear combination of the forward, backward and isotropic scattering kernel (FBIS kernel). The solution of the neutron transport equation with Inonu's scattering kernel can be written in terms of the solution of the neutron transport equation for isotropic scattering case. The extrapolation distance is calculated with modified F-N (or method. The numerical values of the extrapolation distance are obtained depending on the secondary neutron numbers and anisotropy coefficients and compared with the available data in the literature values.
Discrete Eigenvalues of Case Spectrum with Anisotropic Scattering
(Taylor & Francis Inc, 2018) Sahni, D. C.; Tureci, R. G.
Discrete eigenvalues of a one-speed linear transport equation with anisotropic scattering are studied. It is shown that there is only one pair of real discrete eigenvalues for linear, quadratic, or triplet scattering for a nonmultiplicative medium. For a multiplicative medium there is one imaginary pair of eigenvalues or at most four eigenvalues. These can form one real and one imaginary pair, two imaginary pairs, or a quartet. The range of parameters for these different situations is derived analytically. These are then supported by numerical results that are tabulated in tables for each type of scattering.
Adaptive arrangement of cyclic prefix length for MC-CDMA systems via multi-objective bat algorithm
(Springer London Ltd, 2018) Seyman, Muhammet Nuri
Multi-carrier multiplexing systems, used in high bit rate communication applications, are more affected by the time- or frequency-dependent fading effects incurring in the channel than the single-carrier systems. When the fading effects at multi-carrier systems are not taken into consideration, inter-carrier interference or inter-symbol interferences that cause bit error rate increase at the receiver would occur. In order to eliminate these interference effects, the cyclic prefix is used in MC-CDMA systems, which are the kind of multi-carrier systems. However, determining how long the CP length is to be used will directly affect both the error and the capacity performance of the system. In this study, multi-objective bat algorithm is proposed for the adaptive arrangement of the CP lengths according to the channel conditions. Contrary to the standard CP determination methods, not only the bit errors are minimized, but also the maximization of the channel capacity is provided by the utilization of MOBA.
Subcarrier Allocation Algorithm Based on Greedy-Like in Multi Carrier Code Division Multiple Access Systems
(Kaunas Univ Technology, 2017) Seyman, Muhammet Nuri; Demiral, Bircan
One of the most important issues to be taken into consideration in multi carrier communication systems with multi users is the assignment of the available resources to the users efficiently. Thus, how to determine the number of subcarriers to be allocated to the users has an important role with regards to data rate and error performance of the system when active users are increased in multi carrier system. In this study by using Greedy-Like algorithm, the subcarriers in MC-CDMA systems are optimal allocated to the users and the efficiency of this algorithm compared with other algorithms in terms of bit error and bit rate performance.
Half-space albedo problem with modified F-N' method for linear and quadratic anisotropic scattering
(Carl Hanser Verlag, 2017) Tureci, R. G.; Tureci, D.
One speed, time independent and homogeneous medium neutron transport equation can be solved with the anisotropic scattering which includes both the linear anisotropic and the quadratic anisotropic scattering properties. Having solved Case's eigenfunctions and the orthogonality relations among these eigenfunctions, some neutron transport problems such as albedo problem can be calculated as numerically by using numerical or semi-analytic methods. In this study the half-space albedo problem is investigated by using the modified F-N method.
An approach to estimate occupational accidents using least-squares support vector machines
(Academic Publication Council, 2017) Ceylan, Huseyin; Parlakyildiz, Sakir
Least-squares support vector machines represent an emerging technique that has been adopted to estimate accidents. In this study, occupational accident estimation models were developed using the least-squares support vector machine method for the Republic of Turkey. In addition, linear regression analysis, nonlinear regression analysis, and artificial neural network models were considered. During the development phase of the models, statistical data from 1970 to 2012 were used to consider parameters such as insured workers, workplaces, occupational accidents, deaths, and permanent incapacities. Using these models, the numbers of accidents, deaths, and permanent incapacities resulting from occupational accidents were estimated for three different scenarios in the Republic of Turkey through the end of 2025. The performances of the developed models were evaluated considering the mean absolute percent errors and the mean absolute errors. In addition, we compared the least-squares support vector machine, linear regression analysis, nonlinear regression analysis, and artificial neural network methods in terms of their estimation performances. Our simulation results demonstrate that the proposed least-squares support vector machine model outperforms other techniques in terms of accuracy and has a rapid convergence capability when estimating occupational accidents.
Slab albedo for linearly and quadratically anisotropic scattering kernel with modified F-N method
(Carl Hanser Verlag, 2017) Tureci, R. G.; Tureci, D.
One speed, time independent and homogeneous medium neutron transport equation is solved with the anisotropic scattering which includes both the linearly and the quadratically anisotropic scattering kernel. Having written Case's eigenfunctions and the orthogonality relations among of these eigenfunctions, slab albedo problem is investigated as numerically by using Modified F-N method. Selected numerical results are pesented in tables.
The critical slab problem for pure-triplet anisotropic scattering by singular eigenfunction method
(Carl Hanser Verlag, 2017) Tureci, R. G.; Tureci, D.
The infinite medium Green function can be written by using the jump condition, found Case's eigenfunctions. Thus, any reactor theory problem which is inplane geometry such the criticality problem as can be investigated by using the proper boundary conditions and suggested flux definitions. By using the criticality equation the critical thicknesses can be calculated as numerically. The selected numerical results can be tabulated.
A Novel Subcarrier Allocation Algorithm for MC–CDMA Systems
(Slovak Univ Technology, 2016) Seyman, Muhammet Nuri; Sacakli, Bircan
Multi carrier modulation techniques such as MC-CDMA are used in high-speed communication applications. Due to MC-CDMA being a multiuser in technology, the subcarrier quantity allocated per user decreases in case the quantity of active users increases. Consequently, data rates per user are reduced with the increase in the bit error rate (BER). Efficient allocation of subcarriers to users within the system can aid the overcoming of this problem. This study develops a new algorithm for subcarrier allocation and system performance improvement in terms of BER, and data rates in comparison to other algorithms were ensured.
Solving the criticality problem with the reflected boundary condition for the triplet anisotropic scattering with the modified FN method
(Carl Hanser Verlag, 2015) Türeci, R. Gökhan
One speed, time independent neutron transport equation in slab geometry can be solved with the triplet anisotropic scattering for the criticality problem with the reflected boundary condition. The value of the critical slab thickness is investigated numerically by using the Modified F-N (H-N) method. Case's eigenfunctions, normalization relation and orthogonality relations must be derived for this scattering in order to use the Modified FN method. Some selected values, which can be calculated from the criticality equation, can be tabulated. Also the term which comes from the Poincare-Bertrand formula may be added to the orthogonality formula of the continuum eigenfunction.
Due Date Single Machine Scheduling Problems with Nonlinear Deterioration and Learning Effects and Past Sequence Dependent Setup Times
(Hindawi Ltd, 2014) Ceylan, Huseyin
We present some problems against due dates with nonlinear learning and deterioration effects and past sequence dependent setup times. In this study, two effects (learning and deterioration) are used for the same processing time. The processing time of a job is shorter if it is scheduled later, rather than in the sequence. This phenomenon is known in the literature as a "learning effect." On the other hand, in many realistic scheduling settings, a job processed later consumes more time than the same job processed earlier-this is known as scheduling with deteriorating jobs. In the past sequence dependent setup times approach, the setup time of a job is proportionate to the sum of processing times of the jobs already scheduled. In this study, we demonstrated that some problems with due dates remain polynomially solvable. However, for some other problems, we concentrated on finding polynomially solves under their special cases.
An Artificial Neural Networks Approach to Estimate Occupational Accident: A National Perspective for Turkey
(Hindawi Ltd, 2014) Ceylan, Huseyin
Occupational accident estimation models were developed by using artificial neural networks (ANNs) for Turkey. Using these models the number of occupational accidents and death and permanent incapacity numbers resulting from occupational accidents were estimated for Turkey until the year of 2025 by the three different scenarios. In the development of the models, insured workers, workplace, occupational accident, death, and permanent incapacity values were used as model parameters with data between 1970 and 2012. 2-5-1 neural network architecture was selected as the best network architecture. Sigmoid was used in hidden layers and linear function was used at output layer. The feed forward back propagation algorithm was used to train the network. In order to obtain a useful model, the network was trained between 1970 and 1999 to estimate the values of 2000 to 2012. The result was compared with the real values and it was seen that it is applicable for this aim. The performances of all developed models were evaluated using mean absolute percent errors (MAPE), mean absolute errors (MAE), and root mean square errors (RMSE).
Albedo and constant source problems for extremely anisotropic scattering
(Carl Hanser Verlag, 2013) Kocmen, M. A.; Tegmen, A.; Tureci, D.; Gulecyuz, M. C.; Tureci, R. G.
The half-space albedo problem and the constant source problem have been solved for a combination of the linearly anisotropic scattering and Inonu's scattering functions. The linear transport equation for extremely anisotropic scattering kernel can be converted into an equivalent equation with a linearly anisotropic scattering kernel and the modified F-N method can be used for albedo calculations.
MIMO-OFDM Channel Estimation Using ANFIS
(Kaunas Univ Technology, 2012) Seyman, M. N.; Taspinar, N.
M. N. Seyman, N. Taspinar. MIMO-OFDM Channel Estimation Using ANFIS // Electronics and Electrical Engineering. - Kaunas: Technologija, 2012. - No. 4(120). - P. 75-78. In this paper, adaptive neuro fuzzy inference system (ANFIS) model is proposed for channel estimation in MIMO-OFDM system and the performance of this estimator is compared to the least square error (LS), least mean square error (LMS) algorithms by computer simulations. According to the simulations, ANFIS performs better than LS and LMS algorithms. Moreover, there is no need of sending pilot tones which are necessary for classical algorithms, in ANFIS. Therefore the ANFIS is bandwidth efficient algorithm. Ill. 4, bibl. 15, tabl. 1 (in English; abstracts in English and Lithuanian).
Channel Estimation Based on Neural Network With Feedback for Mimo Ofdm Mobile Communication Systems
(Taylor & Francis Inc, 2012) Seyman, M. Nuri; Taspinar, Necmi
Multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) has received a great deal of attention of recently in achieving high data rate in wireless communication systems such as WIMAX. Channel estimation is, however, a critical issue for coherent demodulation. In this paper, a new channel estimator based on neural network with feedback for MIMO-OFDM mobile system is designed and its performance is compared to the least square error (LS), least mean square error (LMS), minimum mean square error (MMSE) algorithms and neural network without feedback by using computer simulations. Simulation results demonstrate that our proposed system is an effective solution to channel estimation in time varying fast fading channels without any knowledge of channel statistics and noise information.
Particle swarm optimization for pilot tones design in MIMO-OFDM systems
(Springer, 2011) Seyman, Muhammet Nuri; Taspinar, Necmi
Channel estimation is an essential task in MIMO-OFDM systems for coherent demodulation and data detection. Also designing pilot tones that affect the channel estimation performance is an important issue for these systems. For this reason, in this article we propose particle swarm optimization (PSO) to optimize placement and power of the comb-type pilot tones that are used for least square (LS) channel estimation in MIMO-OFDM systems. To optimize the pilot tones, upper bound of MSE is used as the objective function of PSO. The effects of Doppler shifts on designing pilot tones are also investigated. According to the simulation results, PSO is an effective solution for designing pilot tones.

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