Suchergebnisse

Wireless Sensor Networks WSNs are emerged as effective network types which mainly depend on employing very small manufactured sensor nodes to aggregate the environmental data and then transfer it toward the concerned node. Some tactical applications such as medical, military, monitoring, emergency, and others require high density of WSN in limited area. Dense WSNs is a special type of WSNs in which very large density for the deployed nodes and also for the exchanged data are considered. Routing process in DWSNs requires special design due to its unique characteristics and requirements. This paper investigates the characteristics, design and challenges in routing protocols of DWSNs. Furthermore; the paper classifies the routing protocols based on different criteria. The paper ends up with an evaluation of several hierarchal and flat-based routing protocols based on different performance criteria. Finally some open research areas, conclusion remarks and future works are presented.

Fabrication and investigation of the properties of CdSe/ZnS core/shell for the luminescent solar concentrates (LSC) application is presented. An increase of the efficiency of a silicon solar cell was obtained by applying the LSC. The increase was a result of the optical properties of the semiconductor nanoparticles CdSe/ZnS core/shell that were deposited over the top surface of the silicon solar cell facing the illumination source (Halogen lamp). The gravity force was invested for the film deposition process.The optical properties of these nanoparticles were studied. The absorption spectra for the CdSe/ZnS core-shell were 270-600nm, i.e., located within the spectral response area of the examined solar cell. The energy gap values for CdSe were 2.5 eV and 3.3eV for ZnS. X-Ray Diffraction (XRD) analysis was adopted and showed that the particle dimensions are within the nanometer scale.The efficiency value of the bare solar cell was 7.3%, whereas the value was increased to 8.0 % by applying the CdSe/ZnS core/shell LSC, indicating an efficiency gain percentage of 9.59%.

This research evaluates the optical properties of an inhomogeneous and non-paraxial system using a solar ball lens (SBL) as a new thermal solar concentrated collector. This evaluation is based on detecting a diacaustic curve in a straightforward and accurate manner, with the diagnostic relying on image processing as a computational tool using the MATLAB program rather than a complicated numerical analytic procedure. The circle of least confusion (CLC) of the (SBL), (Fluorinated ethylene propylene (FEP) polymer – water core), was calculated. Furthermore, the study evaluated the maximum geometrical concentration ratio (G C) of refracted solar radiation that can be captured by a receiver of the (SBL). Without energy losses due to spherical aberration, the (G C) ratio was (14.10) at (h/r) ratio, circular aperture radius to ball radius, around (0.6). The investigation also revealed an aplanatic point for preventing the development of optical envelope inside the solar ball lens at (h/r) equal to 0.8638, as well as a maximum (h/r) value of 0.7351 for collecting solar radiation.