Yazar "Yuzer, A. H." seçeneğine göre listele

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    Memory Polynomial with Shaped Memory Delay Profile and Modeling the Thermal Memory Effect
    (Ieee, 2013) Yuzer, A. H.; Bassam, S. A.; Ghannouchi, F. M.; Demir, S.
    This paper presents a proposal for a new memory polynomial modeling technique with non-uniform delay taps to capture the thermal memory effects in power amplifiers. In the proposed modeling structure, each order of the memory polynomial is assigned a different memory delay. The delay profile is an exponentially shaped function, instead of equal unit delays for all memory polynomial branches. Three different metrics, the memory effect modeling ratio (MEMR) and the normalized mean square error (NMSE) and spectrum error (SE) are used to benchmark the proposed exponentially shaped delay profile memorial polynomial model performance against previously published models, namely the memoryless, the unit delay and sparse delay memory based polynomial models. The model coefficients of four models are extracted for three different excitation signals, which were selected as a 64-QAM signal around 2.14 GHz with 20 kHz, 30 kHz and 40 kHz bandwidths, ensuring that the thermal memory effects dominate the electrical memory effects. It is shown that the proposed model outperforms all the previously published models for all three excitation signals used in the experiment.
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    A Novel Wearable Real-Time Sleep Apnea Detection System Based on the Acceleration Sensor
    (Elsevier Science Inc, 2020) Yuzer, A. H.; Sumbul, H.; Polat, K.
    Background and objective: The apnea syndrome is characterized by an abnormal breath pause or reduction in the airflow during sleep. It is reported in the literature that, it affects 2% of middle-aged women and 4% of middle-aged men, approximately. This study has vital importance, especially for the elderly, the disabled, and pediatric sleep apnea patients. Methods: In this study, a device is developed to detect apnea events to alert the patient. The device records continuously accelerations on the diaphragm by using an acceleration sensor, which is placed on the patient's diaphragm. When the apnea is detected by the accelerometer-based system, a signal is sent to the wristband, and then the vibration motor on the wristband vibrates until the patient starts breathing again. The force of the vibration motor can be adjusted according to the patients' sleep debt, especially for elderly, disabled, or pediatric patients. There is no need for a sleeping room to see the patients' breathing properties since those parameters can be stored by using the developed device on a secure digital memory card (SD) at patients' homes during sleeping. Results: A study group were formed of 10 patients (4 males (40%) and 6 females (60%)) with different characteristics ((mean] age, 36.3; height, 169.6 cm; and body weight, 81.4 kg). The patients in the study group have sleep apnea (SA). All the apnea events were detected, and all the patients were successfully alerted. Also, the lying position, which is a significant issue, is performed in this study. Conclusions: This work proposed using an acceleration sensor as a reliable method of sleep apnea screening, detection of an apnea event, sending alert to the patient, and detection of the patient lying position. The developed device is more economical, comfortable, and convenient than existing systems for not only the patients but also the doctors. The patients can easily use this device in their home environment. (C) 2019 AGBM. Published by Elsevier Masson SAS. All rights reserved.
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    Wearable Textile Fabric Based 3D Metamaterials Absorber in X-Band
    (Applied Computational Electromagnetics Soc, 2020) Delihasanlar, E.; Yuzer, A. H.
    In this paper, a new wearable (flexible) textile fabric based 3D metamaterials absorber (MMA) structure is proposed. The proposed MMA was created from three layers; weft-knitted fabric, silicone, and plain weave fabric and then, it was simulated in Computer Simulation Technology (CST). It was obtained maximum absorption power (99.66%) at 9.38 GHz, and the average absorption power of 81-95% was obtained in the frequency range of 8 to 12 GHz depending on the incident angle in the simulation. The effect of the wearable textile structure on absorption was investigated. When compared with other materials, it can be said that the proposed MMA is broadband, incident angle independent, TE and TM polarization-independent, flexible, breathable, wearable, ease of fabrication, practical, low weight, and cost advantage. With this designed the textile fabric-based MMA, it can be obtained both low reflection coefficients and low transmission coefficients at broadband X-band frequencies. This provides a good solution for the cloaking of radar systems.