From carbon nanotubes and silicate layers to graphene platelets for polymer nanocomposites

In spite of extensive studies conducted on carbon nanotubes and silicate layers for their polymer-based nanocomposites, the rise of graphene now provides a more promising candidate due to its exceptionally high mechanical performance and electrical and thermal conductivities. The present study developed a facile approach to fabricate epoxy–graphene nanocomposites by thermally expanding a commercial product followed by ultrasonication and solution-compounding with epoxy, and investigated their morphologies, mechanical properties, electrical conductivity and thermal mechanical behaviour. Graphene platelets (GnPs) of 3.5

Performance and security measure of clustering protocols for sensor networks

Micro sensor nodes are now easily available and are very cheap. These resource constrained nodes are spread in remote locations to gather data. There are some energy efficient clustering protocols that are known to work well for sensor networks. The performance of these algorithms are mainly measured by the their energy consumption. In this thesis, we develop a performance measure for these algorithms that includes the energy spent, the time delay incurred in the whole process and the information loss. We have formulated a novel metric, the entropy based information loss metric, which to the best of our knowledge has not been previously addressed. We then optimize the joint performance measure which is a combination of these different metrics to yield the optimal clustering configuration.;Security is a key concern in many sensor network scenarios. In this thesis we analyze the performance differences in existing clustering protocols when security is added. In particular, we analyze how the optimal configuration of the LEACH protocol changes when we apply a pre deployment key distribution based security protocol to it.;The final contribution of this thesis is a new secure clustering protocol for sensor networks. In particular, this is a grid based secure solution to a commonly used clustering protocol, the LEACH protocol. We show that our protocol, the GS-LEACH protocol is more energy efficient than any of the existing secure flavors of LEACH. In addition, our protocol is more scalable to regions of different shapes and sizes and provides uniform coverage due to the grid structure of the clusters, thereby guaranteeing a better quality of the information collected

BATSEN: Modifying the BATMAN Routing Protocol for Wireless Sensor Networks

The proliferation of autonomous Wireless Sensor Networks (WSN) has spawned research seeking power efficient communications to improve the lifetime of sensor motes. WSNs are characterized by their power limitations, wireless transceivers, and the converge-cast communications techniques. WSN motes use low-power, lossy radio systems deployed in dense, random topologies, working sympathetically to sense and notify a sink node of the detectable information. In an effort to extend the life of battery powered motes, and hence the life of the network, various routing protocols have been suggested in an effort to optimize converge-cast delivery of sensor data. It is well known that reducing the overhead required to perform converge-cast routing and communications reduces the effects of the primary power drain in the mote, the transceiver. Furthermore, WSNs are not well protected; network security costs energy both in computation and in RF transmission. This paper investigates the use of a Mobile Ad-hoc Networking (MANET) routing protocol known as B.A.T.M.A.N. in WSN. This thesis proposes that the features of B.A.T.M.A.N. in the MANET realm may prove beneficial to the WSN routing domain; and that slight modifications to the routing technique may prove beneficial beyond current protocol technologies. The B.A.T.M.A.N. variant will be compared against the contemporary LEACH WSN routing protocol to discern any potential energy savings

Proactive Highly Ambulatory Sensor Routing (PHASeR) protocol for mobile wireless sensor networks

This paper presents a novel multihop routing protocol for mobile wireless sensor networks called PHASeR (Proactive Highly Ambulatory Sensor Routing). The proposed protocol uses a simple hop-count metric to enable the dynamic and robust routing of data towards the sink in mobile environments. It is motivated by the application of radiation mapping by unmanned vehicles, which requires the reliable and timely delivery of regular measurements to the sink. PHASeR maintains a gradient metric in mobile environments by using a global TDMA MAC layer. It also uses the technique of blind forwarding to pass messages through the network in a multipath manner. PHASeR is analysed mathematically based on packet delivery ratio, average packet delay, throughput and overhead. It is then simulated with varying mobility, scalability and traffic loads. The protocol gives good results over all measures, which suggests that it may also be suitable for a wider array of emerging applications

A Grey Wolf Optimization-Based Clustering Approach for Energy Efficiency in Wireless Sensor Networks

In the realm of Wireless Sensor Networks, the longevity of a sensor node's battery is pivotal, especially since these nodes are often deployed in locations where battery replacement is not feasible. Heterogeneous networks introduce additional challenges due to varying buffer capacities among nodes, necessitating timely data transmission to prevent loss from buffer overflows. Despite numerous attempts to address these issues, previous solutions have been deficient in significant respects. Our innovative strategy employs Grey Wolf Optimization for Cluster Head selection within heterogeneous networks, aiming to concurrently optimise energy efficiency and buffer capacity. We conducted comprehensive simulations using Network Simulator 2, with results analysed in MATLAB, focusing on metrics such as energy depletion rates, remaining energy, node-to-node distance, node count, packet delivery, and average energy in the cluster head selection process. Our approach was benchmarked against leading protocols like LEACH and PEGASIS, considering five key performance indicators: energy usage, network lifespan, the survival rate of nodes over time, data throughput, and remaining network energy. The simulations demonstrate that our Grey Wolf Optimisation method outperforms conventional protocols, showing a 9% reduction in energy usage, a 12% increase in node longevity, a 9.8% improvement in data packet delivery, and a 12.2% boost in data throughput

Energy Efficient Design of Wireless Ad Hoc Networks

The concept of wireless is not new. When the packet switching technology, the fabric of the Internet was introduced by the Department of Defense, the ARPANET ,it understood the potential of packet switched radio technology to interconnect mobile nodes .The DARPA around early 70’s helped establish the base of ad hoc wireless networking. This is a technology that enables untethered wireless networking environments where there is no wired or cellular infrastructure. Wireless Ad hoc Networks since then is a fast developing research area with a vast spectrum of applications. Wireless sensor network systems enable the reliable monitoring of a variety of environments for both civil and military applications. The Energy efficiency continues to be a key factor in limiting the deployability of ad-hoc networks. Deploying an energy efficient system exploiting the maximum lifetime of the network has remained a great challenge since years. The time period from the instant at which the network starts functioning to the time instant at which the first network node runs out of energy, i.e. the network lifetime is largely dependent on the system energy efficiency. This thesis looks at energy efficient protocols, which can have significant impact on the lifetime of these networks. The cluster heads get drain out maximum energy in the wireless ad hoc networks. The proposed algorithm deals with minimizing the rate of dissipation of energy of cluster heads. The algorithm LEAD deals with energy efficient round scheduling of cluster head followed by allocation of nodes to the cluster heads maximizing network lifetime using ANDA