Spectrum sensing is a critical functionality of Cognitive Radio(CR) systems. There are number of spectrum sensing techniques. One of techniques is energy detection. Energy detection is the simplest detection method and is the most commonly used. But, energy detection has a hidden terminal problem in real wireless communication, because of SU can be affected by frequency fading and shadowing. Co...

The limited spectrum resources and dramatic growth of high data rate communications have motivated opportunistic spectrum access using the promising concept of cognitive radio networks. Although this concept has emerged primarily to enhance spectrum utilization, the importance of energy consumption poses new challenges, because energy efficiency and communication performance can be at odds. In ...

Spectrum sensing is an essential function that enables cognitive radio technology to explore spectral holes and resourcefully access them without any harmful interference to the licenses user. Spectrum sensing done by a single node is highly affected by fading and shadowing. Thus, to overcome this, cooperative spectrum sensing was introduced. Currently, the advancements in multiple antennas hav...

PURPOSE Energy-resolved CT has the potential to improve the contrast-to-noise ratio (CNR) through optimal weighting of photons detected in energy bins. In general, optimal weighting gives higher weight to the lower energy photons that contain the most contrast information. However, low-energy photons are generally most corrupted by scatter and spectrum tailing, an effect caused by the limited e...

The cognitive radio technology can provide dynamic spectrum access and improve the efficiency of spectrum utilization. Spectrum sensing is one of the key technologies of cognitive radio networks. The spectrum sensing performance of cognitive radio networks will be greatly reduced in the low SNR environment, especially when using energy detection. Due to the monostable stochastic resonance syste...

background: the assessment of rbe quantity in the treatment of cancer tumors with proton beams in treatment planning systems (tps) is of high significance. given the significance of the issue and the studies conducted in the literature, this quantity is fixed and is taken as equal to 1.1. objective: the main objective of this study was to assess rbe quantity of proton beams and their variations...

cadmium oxide (cdo) nanoparticles were prepared by precipitation method using cadmium acetate and ammonia solution. presence of chemical species, were verified by fourier transform infra red (ftir) spectrum. from x-ray diffraction (xrd) spectrum the particle size, d-spacing value and structure of the nanoparticle were analysed. size of the nanoparticles and the elemental composition were detect...

In this thesis, first, we address the problem of energy efficiency for spectrum sensing. We propose a combined censoring and ”on/off” scheme as an energy efficient technique for cognitive radio networks. We maximize the lifetime of the spectrum sensing system by minimizing the energy consumption of the system subject to a specific detection performance constraint. We show that our proposed tech...

We present optical absorption spectra in the UV-visible range (1.6 eV < ℏω < 5.5 eV) of mass selected neutral copper clusters Cu(n)(n = 1-9) embedded in a solid neon matrix at 7 K. The atom and the dimer have already been measured in neon matrices, while the absorption spectra for sizes between Cu(3) and Cu(9) are entirely (n = 6-9) or in great part new. They show a higher complexity and a larg...