Influence of reaction time and synthesis temperature on the physical properties of ZnO nanoparticles synthesized by the hydrothermal method

Influence of synthesis temperature and reaction time on the structural and optical properties of ZnO nanoparticles synthesized by the hydrothermal method was investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy-dispersive X-ray, Fourier transform infra-red spectroscopy, and UV–visible and fluorescence spectroscopy. The XRD pattern and HR-TEM images confirmed the presence of crystalline hexagonal wurtzite ZnO nanoparticles with average crystallite size in the range 30–40 nm. Their energy gap determined by fluorescence was found to depend on the synthesis temperature and reaction time with values in the range 2.90–3.78 eV. Thermal analysis, thermogravimetric and the differential scanning calorimetry were used to study the thermal reactions and weight loss with heat of the prepared ZnO nanoparticles

Localization in wireless sensor networks using three masters

In wireless sensor networks, sensor node localization is an important topic because sensor nodes are randomly scattered in the region of interest and they get connected into the network on their own. Localization information is needed in routing of data, reducing energy consumption and in location dependent data acquisition. We propose a localization scheme plus a medium access protocol that: (a) reduces power consumption; (b) does not require high power beacons; (c) provides better localization accuracy; and (d) helps in reducing collisions. The proposed localization scheme is based on received signal strength by the three masters. Moreover, it is a distributed algorithm.© IEE