Yazar "Gömeç, Meltem" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    A novel gfdm waveform design based on cascaded wht-lwt transform for the beyond 5g wireless communications
    (MDPI AG, 2021) Maraş, Meryem; Ayvaz, Elif Nur; Gömeç, Meltem; Savaşcıhabeş, Asuman; Özen, Ali
    In this paper, a new WHT-LWT-GFDM waveform obtained by combining Walsh–Hada-mard 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 performance 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. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
  • [ X ]
    Öğe
    The effect of different curing units on the degree of polymerization of different composite resins
    (J Oral Res Rev, 2021) Karataş, Özcan; Gömeç, Meltem; Ayvaz, Elif Nur; Maraş, Meryem
    Objective: The aim of this study was to investigate the degree of polymerization of composite resins cured with different light-curing units (LCUs). Materials and Methods: Three bulk-fill composite (Beautifil Bulk-Fill Giomer, Filtek Bulk-Fill, and X-Tra Fill) and a methacrylate-based composite (Filtek Z250) were used in this study. Thirty disc-shaped specimens, 4 mm thick, were prepared from each composite resin. Specimens were divided into three groups and polymerized with light-emitting diode (LED), Plasma arch curing unit (PAC), and quartz-tungsten halogen LCU. The bottom and top surface microhardness of the specimens stored in distilled water for 24 h at 37°C after polymerization was measured with a universal test device. The hardness ratio (HR) of specimens was calculated by the bottom surface microhardness/top surface microhardness formula. Data were analyzed by two-way ANOVA and Tukey’s least significant difference post hoc tests (? = 0.05). Results: Statistically significant differences were detected between the mean HR values of the specimens polymerized with different LCUs (P < 0.05). The mean HR values of Beautifil Bulk-Fill Giomer specimens were found to be statistically significantly lower than other composites (P < 0.05). The mean HR values of the specimens polymerized with PAC LCU were found to be statistically significantly lower than other LCUs (P < 0.05). Conclusion: The degree of polymerization of the composite resin restoration may be affected by the structural properties of the resin and the type of LCU. The clinician may use alternative techniques, especially in deep cavities.