Didem KAYA

Makale/Derleme | 2016 | TAF Preventive Medicine Bulletin

Amaç: Bu çalışma hemşirelik ve ebelik öğrencilerinde premenstrual sendrom (PMS) yaygınlığını ve PMS ile sigara içme davranışı arasındaki ilişkiyi belirlemek amacıyla yapılmıştır. Yöntem: Çalışmanın örneklemini 584 hemşirelik ve ebelik öğrencisi oluşturmuştur (hemşirelik öğrencisi: 334, ebelik öğrencisi: 250). Veriler Bireysel ve Sigara İçme Davranışı Özellikleri Formu, Premenstrual Sendrom Ölçeği (PMSÖ), Fagerstrom Nikotin Tolerans Testi (FNTT) ile toplanmıştır. Verilerin değerlendirilmesinde Ki-Kare ve Varyans Analizi testleri kullanılmıştır. Bulgular: Öğrencilerin yaş ortalaması 19,94 (SD=1,77)’tür. Öğrencilerin menarş yaş ortalam . . .ası 13,27 (SD=1,19) olup, %53,6’sının menstrual siklusu düzenlidir. Öğrencilerde PMS yaygınlığı %33’tür. Sigara içme durumuna göre PMS yaygınlığı karşılaştırıldığında gruplar arasında anlamlı bir fark olduğu bulunmuştur ( Daha fazlası Daha az

Ali ÖZEN | Büşra AVCI | Gazihan AYKIRI | Kudret KARAERİK | Elif Büşra TUNA | Sabiha YAŞAR | Hayriye SİNOP | Yusuf İslam TEK

Bildiri | 2020 | IEEE 2nd International Conference on Electrical, Communication and Computer Engineering, ICECCE 2020 , pp.904 - 907

Visible Light Communication (VLC), an alternative to radio frequency (RF), was born as a promising technology. In VLC systems, orthogonal frequency division multiplexing (OFDM) has received much attention due to its high data rate, simple equalization and robustness against inter symbol interference (ISI). However, high peak to average power ratio (PAPR) and LED non-linearity have remarkable effects on the performance of indoor VLC-OFDM systems. Asymmetrically clipped optical OFDM (ACO-OFDM) is a technique that sacrifices spectral efficiency to transmit a unipolar frequency division multiplexed signal over a unipolar channel. In thi . . .s study, fast Walsh Hadamard transform based ACO-OFDM (FWHT-ACO-OFDM) method is proposed to improve the performance of ACO-OFDM system by recovering this spectral efficiency. The performance of the proposed method is verified by computer simulation studies for bit error rate (BER) and PAPR performance criteria. From the simulation consequence, it is seen that the proposed method is better for both performance criteria than ACO-OFDM method Daha fazlası Daha az

Ali ÖZEN | Kudret KARAERİK | Elif Büşra TUNA | Yusuf İslam TEK | Hayriye SİNOP | Sabiha YAŞAR | Büşra AVCI | Gazihan AYKIRI

Bildiri | 2020 | IEEE 2nd International Conference on Electrical, Communication and Computer Engineering, ICECCE 2020 , pp.828 - 831

In this paper, combining with the fast Walsh Hadamard transform (FWHT) to improve the performance of the double-tree complex wavelet transform (DTCWT) based OFDM technique developed to eliminate the disadvantages of the orthogonal frequency division multiplexing (OFDM) system is suggested. In order to test the achievement of the proposed DTCWT FWHT OFDM method, computer simulation studies are performed in AWGN and flat Rayleigh fading channel environments. In addition, peak to average power ratio (PAPR) simulations, which are one of the major disadvantages of the classical OFDM system, are also realized. From the achieved simulation . . . results, it is seen that the suggested method has better performance than classical OFDM, Discrete Wavelet Transform (DWT) based OFDM and DTCWT OFDM techniques for both performance metrics Daha fazlası Daha az

Turan Emre KUZU

Makale/Derleme | 2021 | Cumhuriyet Dental Journal

Objectives: The purpose of this study is to compare the tensile strength of different types of surgical suture materials. Materials and Methods: Current study, the tensile strengths of 4 different suture materials was compared. [(1-4/0 silk suture 2-4/0 propylene suture 3-4/0 Polyamide suture 4-4/0 Poly[Glycolide-Co-L-Lactide] (90:10) (PGLA) suture)] The tensile strength of a total of 40 samples was calculated, with 10 samples in each group. In the study, the tensile strength of the sutures was calculated using a universal tester, the sutures were tightened to both poles of the test device and fixed with a distance of 15 mm between . . .the poles, tensile force was applied so that both poles of the test device moved away from each other at a speed of 25cm/min until the sutures broke, and the force value of the sutures at the moment of brake was recorded in Newton units (N) as the tensile strength of suture. Statistical analysis of the data was evaluated by OneWay ANOVA and Tukey HSD tests. Results: In the statistical analysis of the tensile strength of the suture materials, the difference between the tension resistance of the PGLA and Polyamide suture was not statistically significant, but the difference between all other suture materials was statistically significant ( 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

Ali BOZER

Makale/Derleme | 2021 | THE INTERNATIONAL JOURNAL OF RESEARCH ON ENGINEERING STRUCTURES AND MATERIALS

Tuned Liquid Dampers (TLD) consist of a container that is generally partially filled with water. When the sloshing frequency of the water mass is tuned to the fundamental mode of the primary structure a significant amount of sloshing and wave breaking can be achieved which are the primary sources of energy dissipation. Although TLDs are easy to install, operate and maintain; it is generally challenging to model the nonlinear nature of sloshing water. Equivalent mechanical models provide a simplified solution in which sloshing liquid mass, liquid damping, and sloshing frequency are represented by an equivalent mass, damper, spring sy . . .stem. Equivalent mechanical model derivations are generally based on linear sloshing of water mass, which is possible when the water depth/tank length ratio is high and excitation amplitude is low. In this study, a well-known and widely accepted Housner equivalent mechanical model is used to model water sloshing. The water depth/tank length ratio is kept low to enhance the energy dissipation of TLD. The main objective of this study is to experimentally investigate the effectiveness of TLD and check the accuracy of Housner equivalent mechanical model under seismic excitations and low water depth/tank length ratio. Water depth is optimized by the Artificial Bee Colony algorithm which is a population-based optimization algorithm. Frequency sweep analysis and seismic excitations are employed to investigate TLD performance. It is shown that even TLD behavior is modeled by a simplified linear equivalent mechanical model, it is still effective in reducing structural response under large amplitude seismic excitations and low water level/tank length ratios. This is due to more energy dissipation with an increased amount of sloshing and wave breaking Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2021 | Ieee International Conference On Electrical, Computer, Communications And Mechatronics Engineering (Iceccme 2021) , pp.1 - 5

This paper suggests employing channel encoders techniques to develop the attainment of the Flip-OFDM system. Reed Solomon (RS) and convolutional coders (CC) are used as channel coding techniques. Simulation works are carried out in AWGN channel and flat fading optical LOS channel surroundings to compare the performance of Non-Encoded VLC-OFDM, NonEncoded Flip-OFDM, RS-Coded Flip-OFDM and 1/2 rate CC Coded Flip-OFDM systems on bit error rate (BER) achievement benchmark. From the acquired numerical outcomes, it is observed that especially the 1/2 CC Coded Flip-OFDM method is better than other methods. In addition, it is understood fro . . .m the results that with the 1/2 CC Coded Flip-OFDM method, approximately 18 dB SNR development is achieved for the 1E-3 BER value against the Un-Coded VLC-OFDM method. Daha fazlası Daha az

Ali ÖZEN

Bildiri | 2022 | Ieee International Conference On Electrical, Computer, Communications And Mechatronics Engineering (Iceccme 2021) , pp.1 - 4

This article recommends using channel encoders to develop the achievement of optical single carrier frequency domain equalizers (OSC-FDE) in multi-path optical channel environment, which is an alternative to OFDM waveform for visible light communication (VLC) systems. Reed Solomon (RS) and convolutional coding (CC) are used as channel encoders. Computer simulations are made to compare the encoded OSCFDE method with the non-encoded OSC-FDE and VLC-OFDM methods over the bit error rate (BER) achievement criteria. From the acquired outcomes, it is perceived that 18 dB SNR development is achieved, especially with the convolutional coding.

Ali ÖZEN | Asuman SAVAŞÇIHABEŞ

Bildiri | 2021 | IEEE 44th International Conference On Telecommunications And Signal Processing, Tsp 2021 , pp.394 - 398

In this paper, it is recommended to combine the partial transmit sequence (PTS) and amplitude clipping (AC) methods as a solution to the peak to average power ratio (PAPR) problem of multi-carrier (MC) communication systems. The suggested technique is verified on zero tail discrete cosine transform spread OFDM (ZT-DCT-s OFDM), ZT discrete Fourier transform spread OFDM (ZT-DFT-s OFDM) and ZT discrete sine transform spread OFDM (ZT-DST-s OFDM) waveforms, from the next generation waveform alternative to OFDM, with classical OFDM waveform. Computer simulation studies are performed to verify the success of the recommended PTS-AC method o . . .ver bit error rate (BER) and PAPR achievement benchmark. From the obtained results, it is observed that the suggested technique provides approximately 6 dB PAPR enhancement versus the original versions of the waveforms without compromising the BER performance. Daha fazlası Daha az

Alper AYDEMİR

Bildiri | 2019 | Ieee Jordan International Joint Conference On Electrical Engineering And Information Technology (Jeeıt) , pp.495 - 500

Wind has been used to facilitate human life throughout history, but besides being a beneficial renewable energy resource it could transform into a hazardous disaster which could result high loss of life and property. The wind energy was first used for purposes such as produce cereals, transport sailing ships in the sea. Nowadays, wind energy is used in electricity production. The temporal spatial variability and difficulties faced during measurement process of wind speed increased the importance of studies related with wind speed forecast. In this study, Gray estimation method was applied to monthly wind speed data measured between . . .2000-2017 years at three weather stations in Kayseri. Three different GM(1,1) equations were obtained from results of analysis. The average of coefficients obtained from GM(1,1) equations were used to forecast monthly wind speed data between 2014-2017 of other six weather stations located in Kayseri. Accuracy of wind speed estimates were investigated with statistics mean absolute error (MAE) and root mean squared error (RMSE).According to MAE and RMSE criteria, GM(1,1) model has the best result in 18207 station (MAE: 0.28 RMSE: 0.32), while the worst result in 18457 station (MAE: 1.93 RMSE: 1.99). Results of the study indicated that the forecast of wind speed for locations without measurement could be accurately predicted with GM(1,1) model obtained from the other near stations Daha fazlası Daha az