Sürdürülebilir Kalkınma Amaçları
Yayınlar
- MakaleYalnız künye2027Analytical UWB waveform design based on linear combination of Gaussian-modulated sinusoids
Oğuz, Yasin; Kaya, Haydar
This study proposes an analytical ultra wide-band (UWB) waveform design based on linear combination of Gaussian-modulated sine waves to prevent interference with existing narrowband systems, in accordance with the Federal Communications Commission (FCC) UWB spectral mask. The proposed model determines the common pulse duration and the center frequencies of the components in closed-form using the relationships among the number of components, the overlap of components and the design band frequency limits. As a result, UWB waveforms for different design scenarios can be generated without computationally intensive algorithms. The method was evaluated in terms of spectrum utilization efficiency (SUE) within the 3.1-10.6 GHz indoor FCC UWB band. Results show that same SUE can be achieved with fewer components by appropriate overlap level. Comparisons with existing studies demonstrate that the proposed approach provides high performance for similar component numbers while avoiding complex optimization-based models with high computational cost. Moreover, the normalized spectral form and SUE are preserved for different sub-band widths when the analytical parameters are updated according to the new frequency limits. The results demonstrate that the proposed method is an effective waveform design approach due to its low computational complexity, high SUE, and scalability to multi-subband full-band UWB designs.
- BildiriYalnız künye2014A Linear Signal Combination Model for UWB Applications
Oguz, Yasin; Kaya, Haydar
Systems that use UWB technology based on communication with baseband signals of very short duration recently attract attention in communication and radar application, and thereof have been improving rapidly. Because UWB signals occupy a spectrum that is spread about very wide frequency band, one of the principal issues that need to be considered in UWB applications is the frequency allocation. In order to minimize or prevent possible distorting interferences with existing communication systems, spectral distribution of mandatory EIRP limit values has been determined by FCC in UWB applications. In this study, a linear signal combination model has been established and on mathematical expressions have been provided for production of wave forms are suitable UWB emission mask specified by FCC.
- MakaleAçık Erişim2013The effect of prenatal exposure to 900-MHz electromagnetic field on the 21-old-day rat testicle
Hanci, Hatice; Odaci, Ersan; Kaya, Haydar; Aliyazicioǧlu, Yüksel; Turan, Ibrahim; Demir, Selim; Çolakoǧlu, Serdar
The aim of this study was to investigate the effect of exposure to a 900-MHz electromagnetic field (EMF) in the prenatal term on the 21-old-day rat testicle. Pregnant rats were divided into control (CG) and EMF (EMFG) groups. EMFG was exposed to 900-MHz EMF during days 13-21 of pregnancy. Newborn CG rats were obtained from the CG and newborn EMFG (NEMFG) rats from the EMFG. Testicles were extracted at postnatal day 21. Lipid peroxidation and DNA oxidation levels, apoptotic index and histopathological damage scores were compared. NEMFG rats exhibited irregularities in seminiferous tubule basal membrane and epithelium, immature germ cells in the lumen, and a decreased diameter in seminiferous tubules and thickness of epithelium. Apoptotic index, lipid peroxidation and DNA oxidation were higher in NEMFG rats than in NCG. 21-day-old rat testicles exposed to 900-MHz EMF in the prenatal term may be adversely affected, and this effect persists after birth.