Search results

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%.

In this study water-soluble N-Acetyl Cysteine Capped-Cadmium Telluride QDs (NAC/CdTe nanocrystals) using N-acetyl cysteine as a stabilizer were prepared to investigate the utility of quantum dots (QDs) in distinguishing damaged DNA, (extracted from blood samples of leukaemia patients), from intact DNA (extracted from blood samples of healthy individuals) to be used for biosensing application. Based on the optical characterization of the prepared QDs, the XRD results revealed the formation of the NAC-CdTe-QDs with a grain size of 7.1nm. Whereas, the SEM test showed that the spherical size of the NAC-CdTe-QDs lies within 11~33nm. NAC-CdTe-QDs have superior PL emission properties at of 550nm and UV-Vis absorption peak at 300nm. The energy gap measurement through PL and UV–Vis was found to be 2.2eV and 2.3 eV, respectively. The interaction between the synthesized QDs and the extracted genomic DNA (both cancer damaged DNA and healthy undamaged DNA) was analysed optically, and compared to the normal reference DNA. The results showed a shift in the maximum fluorescence emission intensities (observed at 540nm nm for a damaged sample and 535 for a reference cell). Based on the obtained fluorescence results, the present study reached the conclusion that the prepared core/shell QDs could be employed as probes for diagnosing genetically disrupted DNA that is associated with malignant diseases from healthy DNA.

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.