Conference Papers
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Item Effect of volume fraction and particle size of reinforcement on thermal analysis and heat transfer parameters of gravity die cast hypereutectic Al-22% SI alloy matrix composites(2006) Subramanya, P.K.; Hegde, S.; Prabhu, K.N.The properties of cast metal matrix composites are largely dependent on the solidification behaviour which is dictated by the thermophysical properties of the melt, mould and the interfacial heat transfer from the metal to the mould. In the present investigation the thermal analysis parameters and heat transfer aspects of hypereutectic aluminium alloy matrix composites were studied. As the vol% of SiC p increases the total solidification time decreases and the cooling rate increases. The morphology of the primary silicon was very much dependent on the presence of SiC p. The estimated peak heat flux for the composites are lower than matrix alloy melts solidified under similar conditions. The particle size has a negligible influence on the cooling behaviour. However, composite with finer particle size shows slightly higher peak heat flux.Item Microhardness of laser ablated alumina coating on Ti-6A1-4V(2008) Sujaya, C.; Shashikala, H.D.; Umesh, G.; Prabhu, K.N.; Hegde, S.Alumina coated on Titanium alloys find wide tribological applications due to the improvement in hardness of substrate. This paper presents the effect of deposition of alumina by pulsed laser ablation on Vickers hardness of Ti-6A1-4V substrate. Nd: YAG laser of wavelength 1064nm is used with sintered alumina disc as target for ablation. The variation of Vickers microhardness with load in Ti-6A1-4V shows indentation size effect. Proportional Specimen Resistance (P.S.R) model is applied to separate load -independent hardness from the load - dependent hardness. Composite hardness of Alumina coated Ti-6A1-4V is measured for different laser processing conditions. The film hardness has been separated from the composite hardness of the film-substrate system by the use of an approach based on the law of area of mixtures model taking into an account of ISE, due to proportional specimen resistance of the material to indentation. Film hardness of different films produced by varying the target - substrate distance is presented. As the film thickness increases its hardness decreases as compared to bulk hardness. These studies will be useful in the selection of appropriate coating thickness and substrate hardness to achieve a required composite hardness in the design and production of wear-resistant parts of engineering devices.Item Multicasting in wireless mesh networks: Challenges and opportunities(2009) Kumar, K.K.S.; Hegde, S.Wireless Mesh Network (WMN) is a multi-hop wireless network with partial mesh topology, which can replace wired infrastructure backbone in a traditional wireless network, to wireless. It is an exciting new technology that has applications in defense, metro-area Internet access, and disaster management. WMNs are believed to be a highly promising technology and will play an increasingly important role in future generation wireless mobile networks. This paper presents a survey on multicast protocols in wireless mesh networks and factors to be addressed while designing a multicast protocol for wireless mesh networks, like availability of mesh router infrastructure, effect of multiple channels and channel assignment, load balancing, selection of multicast routing metric, effect of guaranteed Quality of Service, andcross layer optimization. © 2009 IEEE.Item AMul: Adaptive multicast routing protocol for multi-hop wireless networks(2011) Panwala, V.; Hegde, S.; Tahiliani, M.P.Wireless Networks have evolved as promising technology for numerous applications to provide Internet access to fixed and mobile wireless devices. Multicasting plays a crucial role in many applications of Wireless Networks. Several routing protocols have been proposed for multicast communication in mobile wireless networks. In this paper we propose a reactive and receiver initiated multicast routing protocol called Adaptive Multicast (AMul) to provide better Quality of Service (QoS) in Wireless Networks. Using simulations, we compare AMul with Protocol for Unified Multicasting through Announcements (PUMA) which is also a reactive and receiver initiated multicast routing protocol for Multi- Hop Wireless Networks. Based on the simulation results, we observe that AMul reduces the overall end to end delay while inducing negligible control overhead in the network. © Springer-Verlag 2011.Item Robust two-way locking protocol for key exchange(2011) Shetty, S.; Hegde, S.; Tahiliani, M.P.Sharing of symmetric key between the sender and receiver for encryption and decryption is considered to be one of the major issues in the communication networks. It is due to the fact that the strength of cryptosystem depends not only on the strength of the key, but also on the underlying key exchange protocol. In this paper, we propose a Robust Two-way Locking Protocol which overcomes the drawback of Diffie-Hellman key exchange protocol in terms of flexibility provided to the sender for selecting the desired key. Moreover we demonstrate the applicability of the proposed protocol in TCP handshake and compare it with Secure TCP which is based on Diffie-Hellman (DH) key exchange protocol. Based on the simulation results it is observed that Robust Two-way Locking (RoToLo) Protocol incurs negligible overhead in the network while providing greater flexibility of key selection to the sender as compared to Secure TCP. © Springer-Verlag 2011.Item Energy efficient load sharing mechanism for multipath routing protocol in wireless sensor networks(2011) Prasanna, K.; Hegde, S.; Shiva, M.G.Many existing energy efficient routing protocols in wireless sensor networks attempt to reduce the energy usage in data routing from source to sink node. Energy efficient routing in wireless sensor network is a paramount requirement to prolong the lifetime of the network. To increase the network lifetime, effective distribution of the traffic from the source node is very much necessary. We would like to propose a novel energy efficient load sharing mechanism in multipath routing for wireless sensor networks. The load sharing mechanism improves the wireless sensor network effectively. © Springer-Verlag 2011.Item Ant-CAMP: Ant based congestion adaptive multi-path routing protocol for wireless networks(2011) Raval, C.; Hegde, S.; Tahiliani, M.P.The advent of mobile computing devices and wide deployment of wireless networks have led to an exponential increase in the internet traffic. Long congestion epochs and frequent link failures in wireless network lead to more number of packets being dropped and incur high end-to-end delay, thereby degrading the overall performance of the network. Congestion control, though mainly incorporated at the transport layer, if coupled with the routing protocols, can significantly improve overall performance of the network. In this paper we propose Ant based Congestion Adaptive Multipath (Ant-CAMP) routing protocol that aims to avoid congestion by proactively sending congestion notification to the sender. The proposed Ant-CAMP routing protocol is implemented in Network Simulator-2 (NS-2) and its performance is compared with Ad-hoc On Demand Multi-Path Distance Vector (AOMDV) in terms of Packet Drops due to Congestion, Packet Delivery Fraction and Average End-to-End Delay. © Springer-Verlag 2011.Item A novel APSP algorithm and its application in multi domain SDN(Institute of Electrical and Electronics Engineers Inc., 2014) Gingupalli, S.C.P.; Hegde, S.Finding the shortest path in networks has always been a major challenge in terms of it's computation time and space complexities. Rather than computing the shortest paths whenever it is needed, they can be pre computed and can be retrieved using hashing techniques effectively. But as the network grows or updates, storing and recomputing requires a lot of memory and processing resources. To overcome this, many approaches which work by effectively decomposing the graph have been proposed. In this paper, one such approach which effectively decomposes the given network into dense components with minimal crossovers between them is being proposed. It was analysed with the existing approaches and shown how the proposed approach works effectively in finding the shortest path in a Multi Domain SDN. It has been tested against different network topologies and in all the cases it is producing promising results. © 2014 IEEE.Item A novel proposal to effectively combine multipath data forwarding for data center networks with congestion control and load balancing using Software-Defined Networking Approach(Institute of Electrical and Electronics Engineers Inc., 2014) Mallik, A.; Hegde, S.Modern data center networks (DCNs) often use multi-rooted topologies, which offer multipath capability, for increased bandwidth and fault tolerance. However, traditional routing algorithms for the Internet have no or limited support for multipath routing, and cannot fully utilize available bandwidth in such DCNs. As a result, they route all the traffic through a single path, and thus form congestion. Multipath (MP) routing might be a good alternative, but is not sufficient alone to handle congestion that comes from the contention of end stations. Dynamic load balancing, on the other hand, protects the network from sudden congestions which could be caused by load spikes or link failures. However, little work has been done to incorporate all these features in a single and comprehensive solution for Data Center Ethernet (DCE). In this paper, we propose a novel method that attempts to integrate dynamic load balancing, multi-path scheme with congestion control (CC), with the use of pure Software-Defined-Networking (SDN) approach. SDN decouples control plane from the data forwarding plane, which reduces the overheads of the network switches. The major objectives that our solution attempts to achieve are, efficient utilization of network resources, high throughput and minimal frame loss. © 2014 IEEE.Item Conjugate Heat Transfer Studies in a Hexagonal Micro Channel(Elsevier Ltd, 2015) Hegde, S.; Narendran, N.; Gnanasekaran, N.This paper reports conjugate heat transfer studies in micro channel heat sink of 3 cm2 which acts as a sink for the heat generating material. The hexagonal micro channel is modeled with surface roughness to counter the manufacturing outcomes. Different combinations of Nano fluids such as ethylene glycol, isopropyl alcohol and de-ionized water are proposed in the numerical study and the maximum heat dissipation is obtained. Simulations are also carried out for various heat flux and different velocities of the fluids. The conjugate heat transfer model is helpful as a forward model in the field of inverse heat transfer wherein the unknown heat flux is estimated by either deterministic or stochastic models. © 2015 The Authors.