SYNTHESIS AND IMPLEMENTATION OF NiZnFe 2 O 4 FERRITES TO DESIGN EMBEDDED SYSTEM FOR HUMIDITY MEASUREMENT
2 ABSTRACT: Along with magnetic properties, the spinel ferrites exhibit promising electrical properties, deployment of which results into evolution of new area of applications as the electronic sensor materials. The electrical properties significantly depend upon the environmental compositions, for which it has been exposed. The electrical resistance of these sensor materials varies not only with gas concentration but also with change in water vapour concentration. With the view to develop an embedded technology based smart sensor module for humidity measurement a sensor material NixZn1-xFe2O4 are synthesized by chemical method and characterized by XRD and IR tools. The x-ray powder diffraction reveals the formation of single phase spinel ferrite, which is also supported by the IR absorption bands attributed to tetrahedral (A) site and octahedral (B) sites. Employing embedded philosophy, the sensor module is designed about AVR ATmega8L microcontroller for humidity measurement. The thick film of materials under investigation, prepared by screen painting technique, is used to sense the concentration of water molecules. Analog part of the system is wired about highly precise instrumentation amplifier AD620. Deployment of on-chip ADC of 10-bit resolution causes to increase in the preciseness of the results. The system is calibrated to the humidity in RH%. The data shown by the system under investigation reveals close match with the standard data.
Electric conduction in Ni–Zn ferrites
Abstract The AC electrical conductivity was studied as function of temperature, frequency and composition for a series of Ni 1− x Zn x Fe 2 O 4 ferrite samples prepared by usual ceramic technique. The experimental results indicated that the AC electrical conductivity σ 2 ( ω ,  T ) increases while the activation energy for electric conduction in ferrimagnetic region E f decreases on increasing the frequency. The real AC ( σ AC ′) and DC ( σ DC ) electrical conductivities increase as the temperature increases indicating that the studied samples are semiconductors. Both σ AC ′ and σ DC increase whereas the Curie temperature T c , activation energies for electric conduction E f and E p (in paramagnetic region) decrease as Zn ion substitution increases. The activation energy for electric conduction E p in the paramagnetic region is higher than that in ferrimagnetic region E f . The parameter B and exponent n for electrical conductivity σ 2 ( ω ,  T ) in the power law σ 2 ( ω ,  T )= Bω n were found, respectively, to be composition and temperature dependent. Both n and B increase as Zn ion substitution increases. n decreases whereas B increases as the temperature increases. Empirical formulae were suggested for the temperature dependence of both n and B ; compositional dependence of electrical conductivity σ , and compositional dependence of n and B .
Climate change, disasters and electricity generation
Abbrevia ons Foreword 1. Introduc on 8 2. The impacts of changing climate pa erns and changing disaster risks on energy 9 op ons and electricity genera on infrastructure 2.1 The rela onship between climate change and disaster risks 10 2.2 The impact of changing climate pa erns and changing disaster risks on electricity 11 genera on from fossil fuels 2.3 The impact of changing climate pa erns and changing disaster risks on electricity 14 from nuclear power 2.4 The impact of changing climate pa erns and changing disaster risks on electricity 17 genera on from renewable energy 2.4.1 Hydropower 17 2.4.2 Wind Energy 19 2.4.3 Bioenergy 22 2.4.4 Solar Energy 24 3. Climate change and changing disaster risks: implica ons for energy policy and 26 planning