Kubulay ÇAĞATAY | İpek YILDIRIM | Kenan BAŞOĞLU

Makale/Derleme | 2021 | Indoor and Built Environment

This study aimed to determine how light direction, window proximity and window dimensions could affect students' perceptual evaluations in design studios. The design studios of the Nuh Naci Yazgan University in Kayseri were selected as the research setting. The ‘semantic differential scale’ composed of 10 adjective pairs was used for determining subjects’ perceptual evaluations of design studios having two different window dimensions. According to the results obtained, when making drawings, right-handed students who received light from a window on the left side were determined to perceive the physical environmental factors of design . . . studios more positively compared to students who received light from a window on the right side. In addition, students sitting near a window in design studios were observed to generally perceive the physical environmental factors more positively than those sitting in the middle close to the window, in the middle away from the window and inside. Furthermore, students who sat in an area with floor to ceiling window were determined to perceive the place more positively compared to those who sat in an area with parapet to ceiling window. These results generally confirmed that light direction, window proximity and window dimensions in design studios are effective on students’ perceptual evaluations Daha fazlası Daha az

Ahmet DOĞAN

Makale/Derleme | 2021 | Engineering Science and Technology, an International Journal

With increasing environmental sensitivity and developing technology, Distributed Generations (DGs), Electric Vehicles Charging Stations (EVCSs), andEnergy Storage Systems(ESSs) have been significant part of adistribution grid. However, inappropriate sitting and sizing of these components may negatively affect the performance of distribution grid. Besides, efficient operation of distribution grid can be achieved by only choosing the proper sizes of DGs, EVCSs, ESSs and placing them at the appropriate locations in the grid. In this paper, a weighted sum multi-objective function is formulated for reducing power loss, increasing voltage . . . level and integration capacity of DGs, EVCSs, ESSs, simultaneously. Also, hybrid Soccer League Competition–Pattern Search (hSLC-PS) optimization algorithm is proposed to improve fine-tune performance of optimization. Simulations are carried out considering time-varying and stochastic nature ofPhotovoltaics(PVs) andWind Turbines(WTs) generations and EVCSs load demand. The performance of the proposed method has been investigated on 33-bus and 85-bus test systems under different conditions and the statistical results are compared to SLC and Grey Wolf Optimization (GWO) algorithms to validate the effectiveness of the proposed algorithm. Statistical results clearly reveal the superiority of hSLC-PS in simultaneous sitting and sizing of DGs, EVCSs and ESSs Daha fazlası Daha az

Ali ÖZEN

Makale/Derleme | 2021 | Journal of Lightwave Technology39 ( 13 ) , pp.4255 - 4261

In this paper, it was proposed a new multicarrier modulation scheme, based on lifting wavelet transform for coherent optical communication systems. This new wave scheme used the energy compaction property of lifting wavelet transform that provides low leakage in subcarriers. The new wave scheme based system was allowed improved performance in terms of bit error rate and reduction in the peak to average power ratio compared to conventional cyclic prefix based OFDM. It was found that the use of the new wave scheme was possible to extend the transmission distance by 100 km and 150 km compared to OFDM for QPSK and 16QAM, respectively. T . . .his was occured because the new wave scheme could provide more frequency localization than OFDM Daha fazlası Daha az

Ali ÖZEN | Asuman SAVAŞÇIHABEŞ

Makale/Derleme | 2020 | IEEJ Transactions on Electrical and Electronic Engineering

A novel concatenated Lifting Wavelet Transform (LWT) and Walsh Hadamard Transform (WHT) with Universal Filtered MultiCarrier (UFMC) waveform is suggested as an alternative to Orthogonal Frequency Division Multiplexing (OFDM) waveformfor the next generation wireless telecommunication systems in this paper. The suggested waveform is composed of LWT andWHT with UFMC waveform. Both the elimination the disadvantages of OFDM and the improvement the achievement of UFMCwaveform, from the fifth generation waveform candidates, has been aimed with the suggested waveform. In order to verify theperformance of the suggested waveform and compare w . . .ith the traditional OFDM, UFMC, and LWT-UFMC waveform computersimulation studies are performed in additive white Gaussian noise and flat Rayleigh fading channel environments. The acquiredcomputer simulation results exhibit that the achievement of the suggested waveform has better than the achievement of thetraditional OFDM, UFMC, and LWT-UFMC waveform.©2021 Institute of Electrical Engineers of Japan. Published by WileyPeriodicals LLC Daha fazlası Daha az

Asuman SAVAŞÇIHABEŞ | Ali ÖZEN

Makale/Derleme | 2021 | Sensors

In this paper, a new WHT-LWT-GFDM waveform obtained by combining Walsh–Hadamard Transform (WHT), Lifting Wavelet Transform (LWT), and Generalized Frequency Division Multiplexing (GFDM) is presented for use in next-generation wireless communication systems. The proposed approach meets the requirement of 5th-generation (5G) and beyond communication schemes in terms of low latency, low peak-to-average-power ratio (PAPR), and low bit-error rate (BER). To verify the performance of the presented waveform, PAPR and BER simulation results were obtained in additive white Gaussian noise (AWGN) and flat Rayleigh fading channels, and the perfor . . .mance of the proposed system was compared with conventional Orthogonal Frequency Division Multiplexing (OFDM), GFDM, and Walsh–Hadamard transform-based GFDM (WHT-GFDM). Simulation results show that the proposed waveform achieves the best BER and PAPR performances and it provides considerable performance gains over the conventional waveforms Daha fazlası Daha az

Asuman SAVAŞÇIHABEŞ | Ali ÖZEN

Makale/Derleme | 2021 | AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS

Orthogonal frequency division multiplexing (OFDM) is widely used in many digital communication systems because of its immunity to inter-symbol interference, high spectral efficiency and capability of handling multipath. Walsh-Hadamard transform (WHT) and discrete wavelet transform (DWT) have also been suggested in order to enhance the performances of multi-carrier wireless communication systems. In general, high peak-to-average power ratio (PAPR) is one of the biggest disadvantages of these systems and OFDM also has this disadvantage. Many techniques such as amplitude clipping and filtering, encoding, interleaving, tone reservation . . .(TR), tone addition (TI), partial transmission sequence (PTS), and selected mapping (SLM) techniques have been proposed to reduce the high PAPR. Without any modification these techniques are useless due to the related symbol addition process. For this reason, we developed a new technique composed of Lifting wavelet transform (LWT) and SLM method in order to decrease the PAPR in multi-carrier systems. The performance of this new LWT-SLM scheme is measured by applying it to zero tail (ZT) discrete Fourier transform-spread OFDM (ZT DFT-s OFDM) and unique word OFDM (UW OFDM) waveforms, which are promising next generation waveforms. Simulation results show that, the ZT DFT-s OFDM system obtains the 3.3 dB PAPR gain and 0.8 dB better bit error rate (BER) performance compared to classical OFDM with proposed scheme without sacrificing BER performance Daha fazlası Daha az

Asuman SAVAŞÇIHABEŞ | Ali ÖZEN

Makale/Derleme | 2021 | Iet Communications

Orthogonal frequency division multiplexing (OFDM) has been widely used in wireless communication systems due to its robustness against the frequency selectivity of fading channels. It provides optimal performance and it also meets the requirements of the next generation communication systems. Although OFDM has these advantages, its spectrum efficiency is usually degraded significantly due to the use of cyclic prefix (CP). In this paper, motivated to deal with this issue, the combined structure of Fast Walsh-Hadamard Transform (FWHT) and Time Domain Equalizer (TDE) is proposed to use in CP-free OFDM systems. The results validated by . . .Monte Carlo simulations decipher the improved performances in terms of spectral efficiencies, bit error rate, peak to average power ratio and out of band emission for using this structure over frequency selective multipath fading channels in CP-free OFDM systems. The acquired simulation results have illustrated that the proposed method provides 20 spectral efficiency without compromising the BER performance Daha fazlası Daha az

Mehmet BİLİM

Makale/Derleme | 2021 | Digital Signal Processing

This study evaluates the performance of single-input multiple-output (SIMO) wireless networks or dual- branch (DB) SIMO scenarios over the η–μ and the λ–μ fading links. First, the probability density functions (PDFs) of the instantaneous signal to noise ratio for a DB SIMO system in the η–μ and the λ–μ fading conditions. Then, the closed-form expressions of the effective rate (ER or effective capacity) for a SIMO network are derived. In addition to this, asymptotic ER expressions for the considered SIMO network are proposed. The analytical capacity expressions with different transmission policies such as optimal rate adaptation with . . . constant transmit power, optimal simultaneous power and rate adaptation, channel inversion with fixed-rate (CIFR), and truncated channel inversion with fixed-rate are obtained for the SIMO network. Furthermore, the capacity expressions with CIFR policy for DB SIMO communications over the η–μ and the λ–μ fading channels are derived by using the proposed PDFs. Finally, the amount of fading expressions for SIMO networks over the η–μ and the λ–μ fading links are proposed by employing the elementary functions. The proposed analytical expressions provide to establish different radio propagation scenarios by adjusting η, λ or μ parameter. To confirm the accuracy of our analysis, the proposed analytical expressions are verified via exact simulation Daha fazlası Daha az

Mehmet BİLİM

Makale/Derleme | 2021 | Peer-to-Peer Networking and Applications

In this study, the performance of hexagonal quadrature amplitude modulation (HQAM) for a dual-branch selection combining (SC) receiver for beyond fifth-generation (B5G) is analyzed in detail. For general applicability, the links are modeled with η-μ fading channels. In this context, analytical expressions of error probability (EP) are derived in terms of the Chernoff, Chiani, Prony (2 and 3 terms), and Trapezoidal approximations for Gaussian Q-function. For the high signal to noise ratio (SNR) analysis, asymptotic EP expression is also derived by using the Chernoff approximation. Further, for the comparison, the analytical EP expres . . .sions with rectangular QAM and quadrature phase-shift keying modulation schemes are obtained by using the Chiani approximation. Moreover, a comprehensive work of various modulation schemes is presented and the effects of fading parameters, type of Gaussian Q-function approximations, and average SNR values of first and second links are highlighted on the EP performance. Finally, to show the accuracy of the proposed analytical derivations, some results for the exact simulations and numerical results are demonstrated Daha fazlası Daha az

Gülçin CANBULUT | Erkan KÖSE | Oğuzhan Ahmet ARIK

Makale/Derleme | 2021 | Soft Computing

One of the most important problems faced in supply chain management is the coordination between supply chain members. Supply chain contracts, such as buyback contract, quantity-flexibility contract, revenue sharing contract, etc., can be used for solving this problem. In revenue sharing contracts, the manufacturer applies a low wholesale price to the retailer and in return shares a portion of the retailer's revenue. In this study, the revenue sharing contracts between the supplier and the retailer are handled as two-person non-constant sum games. There are two players in the game, supplier and retailer, and the main motivation of bo . . .th is to increase their profitability. To this end, the supplier applies different wholesale prices, while the retailer responds by using different revenue sharing rates. In the study, profit functions of the supply chain members are calculated in the event of an income sharing agreement. These functions differ due to changes in supply chain parameters. The profits of the retailer and supplier corresponding to different wholesale prices and revenue sharing rates have been transferred to the two-person non-constant sum game revenue matrix. Then, the best strategies of the supplier and retailer are tried to be determined by the search of equilibrium point which is one of the solution methods that can be used to determine the best strategies in two-person non-constant sum games. The results showed that the solution approaches of game theory can be applied successfully in determining the best strategies that the parties can implement in revenue sharing contracts between the supplier and the retailer Daha fazlası Daha az

Oğuzhan Ahmet ARIK

Makale/Derleme | 2021 | Operational Research An International Journal

Additive manufacturing (AM) is a candidate to be one of the future general-purpose technologies. AM is called with 3D printing, Rapid Prototyping, Direct Digital Manufacturing, layered manufacturing, and/or additive manufacturing. Today, AM is a tool for producing customized small products with small lot sizes. Tomorrow, it will be possible for AM to enter every home and to be used for general purposes. The literature about AM has focused mainly on the technology to decrease the cost of AM, to increase the speed of AM machines, and to increase the common availability of those machines. There are so few papers investigating AM machin . . .es in view of scheduling problems. This paper considers a single AM machine that produces multiple parts in batches and then these parts are assembled to produce desired goods. Most AM machines have limitations because of the area of the machine tray and the height of the machine. Therefore, products are separated into small parts considering the area and height of the machine. Then, these separated small parts are assembled to produce the desired goods. In view of scheduling problems, the proposed problem includes single machine batch scheduling and assembly operations. In this paper, we propose a mixed-integer programming (MIP) model and a fast heuristic method with a simple local search mechanism for the problem. We investigate two cases for the same problem. In the frst, we consider only the one-dimensional assignment of parts to baches and we just design our solution approaches to assign parts to the batch, if the total area of parts is less than or equal to the machine tray’s area. In the second, we modify our solution approaches to consider parts’ lengths and widths while assigning parts to batches in a 2D assignment. In the end, we compare the proposed heuristic with the proposed MIP by using some test problems within time limits for all cases. Experimental results show that the proposed heuristic provides promising results Daha fazlası Daha az

Oğuzhan Ahmet ARIK

Makale/Derleme | 2021 | Neural Computing and Applications

The permutation flow shop scheduling problem has been investigated by researchers for more than 40 years due to its complexity and lots of real-life examples of the problem. Many exact or approximate solution approaches have been presented for the problem. Among solution approaches in the literature, iterated greedy algorithm and its variants are the most effective solution methods for the problem. This paper proposes a hybrid solution algorithm that uses the best components such as local search operators and destruction/construction operators of the variants of iterated greedy algorithm in an artificial bee colony algorithm. An ANO . . .VA is made for determining the most proper components of iterated greedy algorithm. Then, these components are combined with artificial bee colony algorithm. Furthermore, a design of experiment is made for determining the best parameter setting for the proposed hybrid artificial bee colony. The experimental results of the proposed algorithm compared with variants of iterated greedy algorithms in the literature show that the proposed algorithm produces better solutions that deviate less from the optimum or lower-bound solutions for permutation flow shop scheduling problems with the makespan performance criterion Daha fazlası Daha az