Nodes in Mobile Ad Hoc Networks (MANETs) are limited battery powered. That"s why energy efficient routing has become an important optimization criterion in MANETs. The conventional routing protocols do not consider energy of the nodes while selecting routes which leads to early exhaustion of nodes and partitioning of the network. This paper attempts to provide an energy aware routing algorithm. The proposed algorithm finds the transmission energy between the nodes relative to the distance and

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... e performance of the algorithm is analyzed between two metrics Total Transmission energy of a route and Maximum Number of Hops. The proposed algorithm shows efficient energy utilization and increased network lifetime with total transmission energy metric. 7152 II. APPLICATIONS Because of advanced technology, sensor nodes are becoming smaller, cheaper and most powerful. This enables to deploy a large scale sensor networks. Sensors are linked using wireless technologies that employ ubiquitous sensor networks at low data rates, such as RFID, ZigBee, and Bluetooth; and Wi-Fi networks, cellular, and satellite communications at higher data rates. WSN applications offer great opportunities to optimize production where the use of wired networks is prohibitive. A. Tracking chemical composition in environment Wireless networks can be used to remotely monitor pipelines, natural gas leaks, corrosion, H2S content, equipment condition, and real-time reservoir status. An Air Pollution Monitoring System [2] is one of the applications of sensors where geo-sensor network system measures the contamination in the air. Major gases which cause air pollution are Carbon dioxide CO 2 , Nitrogen dioxide NO 2 and Sulphur dioxide SO 2 .Here the role of geo-sensor network is to send the measured quantity of these pollutants to the remote system where the exact processing and abstraction happens. In order to define facts, events and their relationship, this paper uses context model concept [] so that the context of the remote sensed area is understood. This paper also describes air pollution prevention model. This model defines the pollution and the potential polluted area which is based on abstracted data of the previous stage. 7153 hardware on ordinary FPGAs. Low-power optimized FPGAs are able to enhance the computation of several types of algorithms in terms of speed and power consumption in comparison to microcontrollers of commercial sensor nodes. Architectures based on the combination of microcontrollers and FPGA can play a key role in the future of sensor networks, in fields where processing capabilities such as strong cryptography, self-testing and data compression, among others, are paramount. D. Effective Irrigation system WSN applications can be found in agriculture system also. Paper [9] focuses on microcontroller based drip irrigation system. In the proposed system soil moisture sensor are water flow meter are two major components. Microcontroller sends the sensor data to the computer through ZigBee technology [10]. Thus water body is utilized efficiently which leads to save water. Incorporating soil features namely soil pH, soil electrical conductivity; temperature etc. are possible future enhancement to this work. What is ZigBee technology? ZigBee is a worldwide open standard for wireless radio networks in the monitoring and control fields. The standard was developed by the ZigBee Alliance-an association of International companies. What expected from ZigBee is to provide low cost and low power connectivity for equipment that needs very long battery life as several months to several years but does not require data transfer rates as high as those enabled by Bluetooth. Also ZigBee can be implemented larger networks than is possible with Bluetooth. ZigBee compliant wireless devices are operate in the unlicensed RF worldwide (2.4GHz global, 915MHz Americas or 868 MHz Europe). The data rate is 250kbps at 2.4GHz, 40kbps at 915MHz and 20kbps at 868MHz. E. Healthcaremonitoring systems Earlier WSN was applied majorly for military applications, civilian applications and slowly started using it in environmental species monitoring, industrial production, smart home and health care etc. WSN based health care systems have been deployed for applications such as home monitoring for chronic and elderly patients, real-time continuous patient monitoring in hospitals , automated vital sign analysis to reduce the incidents of medical accidents due to human error, and emergency situations [11] . The wireless healthcare applications use medical sensors and environmental sensors, mobile Devices like PDA, laptop and iPhone and more especially wireless communications protocols namely IEEE 802.11, IEEE 802.15.4, Bluetooth etc. Furthermore, a backend server is used for physiological healthcare information (PHI) storage, and for offline analysis of PHIs. III. CONCLUSION Optimizing a wireless sensor network also bring many open issues in the network design. In wireless sensor networks, they contain a lot of constrains, such as energy limitation, decentralized collaboration, and fault tolerance. This paper gave insight of some sensor network applications and also kind of discussion about some recent research domain of WSN. So it is helpful to the beginners those who like to do work on WSN.