wireless sensor networks (wsns) have many applications in the areas of commercial, military and environmental requirements. regarding the deployment of low cost sensor nodes with restricted energy resources, these networks face a lot of security challenges. a basic approach for preparing a secure wireless communication in wsns, is to propose an efficient cryptographic key management protocol be...

sybil attacks pose a serious threat for wireless sensor networks (wsn) security. they can create problems in routing, voting schemes, decision making, distributed storage and sensor re-programming. in a sybil attack,the attacker masquerades as multiple sensor identities, that are actually controlled by one or a few existing attacker nodes. sybil identities are fabricated out of stolen keys, obt...

in this study, a specific ch4 sensor is fabricated based on interdigitated electrode that modified with core-shell of tungsten carbide/tin oxide (wc/sno2) nanoparticles by wet chemical method in different percents of carbon and tungsten. the morphology of wet chemical-synthesized wc/sno2 core-shell was evaluated by different methods such as patterned x-ray diffraction (xrd), and particle size a...

urease was immobilized on platinum electrode both by chemical binding and electropolymerization.the conductometric urea biosensor thus prepared showed a detection limit of 4.9×10-5 m and linear dynamic range from 4.9×10-5 to 5.8×10-3 m for urea concentration when the enzyme is covalently immobilized on pt electrodes. conductometric transducers respond to the changes in ionic strength thereby le...

an extended octagonal ring (eor) transducer was designed and developed to measure forces inside the compression chamber of a large square baler in different directions. the transducer was calibrated by applying forces in three directions simultaneously and independently. the sensor revealed excellent linearity along with small cross sensitivities. horizontal and vertical primary sensitivities o...

soil compaction and moisture content are two of the factors that greatly influence variations in crop yield. capacitance-based sensor is a sensitive device for estimating soil water content. in this method of soil moisture content measurement, soil acts as the dielectric of the capacitor. throughout this research work, a capacitance-based moisture sensor that can measure the soil moisture conte...

wireless sensor networks are composed of hundreds or thousands of small nodes called sensor that work together and are associated with a specific task or tasks to do. each of these nodes includes sensor, processor, communication components, a small memory and a source of energy. it is expected that wireless sensor networks will be used widely in many applications in near future. scalability and...