because of production process and constrains conditions, circular graphene sheet may be opposed to structural defect and pin hole, respectively. some of the defects and pin hole on a circular graphene sheet can be considered as an eccentric hole on the sheet. hence, analyzing behavior of circular graphene sheet with an eccentric hole is important. free vibration of an eccentric annular graphene...

“Spectrum holes” represent the potential opportunities for non-interfering (safe) use of spectrum and can be considered as multidimensional regions within frequency, time, and space. The core challenge for secondary radio systems is to be able to robustly sense when they are within such a spectrum hole. To allow a unified discussion of the core issues in spectrum sensing, the “Weighted Probabil...

In this study, an organic-inorganic semiconductor gas sensor was fabricated to detect ammonia gas. An inorganic semiconductor was a zinc oxide (ZnO) nanowire array produced by atomic layer deposition (ALD) while an organic material was a p-type semiconductor, poly(3-hexylthiophene) (P3HT). P3HT was suitable for the gas sensing application due to its high hole mobility, good stability, and good ...

Field and remote sensing observations in the ablation zone of the Greenland Ice Sheet have revealed a diverse range of ice surface characteristics, primarily reflecting the variable distribution of fine debris (cryoconite). This debris reduces the surface albedo and is therefore an important control on melt rates and ice sheet mass balance. Meanwhile, studies of ice sheet surface biological pro...

The big demand originated by the deployment of smart grids, where millions of sensors need to be deployed using wireless transport to the corresponding concentrator implies a dramatic change on the paradigmatic scenario of wireless communications. The new scenario is defined by very low bandwidth messages from a device but an enormous number of devices. This new scenario represents also an oppo...

We demonstrate a novel Er3+-doped fibre laser operating in orthogonally polarized dual-frequency modes and its application to electric current sensing with frequency read-out. A Faraday rotating mirror and spatial hole burning effects in a gain medium and in a saturable absorber are utilized to control the lasing mode and polarization. The polarization mode beat frequency changes linearly in re...

In cognitive radio, spectrum sensing is a key component for securing the licensed terminal from interference and detects the white spectrum hole to improve the spectrum efficiency. In the existing techniques, the noise uncertainty was either not considered or only detrimental effects are mitigated without much performance improvement. Therefore, a novel dynamicdouble-threshold energy detection ...

[email protected] [email protected] Abstract— Wireless sensor networks are formed by small sensor nodes communicating over wireless links without using a fixed network infrastructure. Each of the sensor nodes is capable of sensing, processing, and transmitting environmental information. Since the sensor nodes are equipped with battery having limited energy, energy efficient information...

Performance evaluation of spectrum sensing in infrastructure based multihop network is very hard to achieve because of the adverse effects of channel fading. In this paper, performance of a multihop link is studied over Nakagami-m distribution. It provides the exact theoretical methodology for the performance analysis of spectrum sensing by evaluating detection probability. Using a cascaded mul...