Browsing by Author "Hegde, S."

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A novel approach to investigate effect of magnetic field on dynamic properties of natural rubber based isotropic thick magnetorheological elastomers in shear mode
(Central South University of Technology f-ysxb@mail.csut.edu.cn, 2015) Hegde, S.; Kiran, K.; Gangadharan, K.V.
The preparation of natural rubber based isotropic thick magnetorheological elastomers (MRE) was focused on by varying the percentage volume concentration of carbonyl iron powder and developing a test set up to test the dynamic properties. Effect of magnetic field on the damping ratio was studied on the amplification region of the transmissibility curve. The viscoelastic dynamic damping nature of the elastomer was also studied by analyzing the force-displacement hysteresis graphs. The results show that MR effect increases with the increase in magnetic field as well as carbonyl iron powder particle concentration. It is observed that softer matrix material produces more MR effect. A maximum of 125% improvement in the loss factor is observed for the MRE with 25% carbonyl iron volume concentration. FEMM simulation shows that as carbonyl iron particle distribution becomes denser, MR effect is improved. FEMM analysis also reveals that if the distance between the adjacent iron particles are reduced from 20 ?m to 10 ?m, a 40% increase in stored energy is observed. © 2014, Central South University Press and Springer-Verlag Berlin Heidelberg.
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. Â© 2014 IEEE.
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. Â© 2014 IEEE.
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.
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. Â© Springer-Verlag 2011.
An experimental investigation on the matrix dependent rheological properties of MRE
(SAGE Publications Ltd, 2024) Poojary, U.R.; Kiran, K.; Hegde, S.; Gangadharan, K.V.
The rheological properties of magnetorheological elastomers are influenced by magnetically sensitive fillers and the elastomer matrix. The ability to respond to an external magnetic field is imparted by the fillers, while the load-bearing capability is determined by the matrix type. In this paper, the effect of matrix material on the properties of magnetorhological elastomer is explored experimentally. Carbonyl iron particle content is varied by 0%, 15% and 25% by volume to produce magnetorheological elastomer samples using natural rubber, silicone rubber and nitrile butadiene rubber matrices. Forced transmissibility test approach was employed to evaluate the field induced variations in the dynamic stiffness and loss factor of magnetorheological elastomers. The dynamic stiffness of nitrile butadiene rubber is the highest, while that of silicone rubber is the lowest. Addition of carbonyl iron particles significantly improves stiffness, although these gains depend on the properties of unfilled matrix. The addition of 25% by volume of carbonyl iron particle increased the dynamic stiffness of a silicone rubber matrix based magnetorheological elastomer by 67.78%, while the similar change in magnetorheological elastomer with nitrile butadiene rubber matrix was 38.58%. The field dependent response of magnetorheological elastomers is governed by the matrix and ferromagnetic filler concentration. These qualities are higher in magnetorheological elastomer with a low initial dynamic stiffness matrix and lower in magnetorheological elastomers with a stiffer matrix. © The Author(s) 2023.
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.
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. Â© Springer-Verlag 2011.
Anti-corrosion treatment for bearing steel
(American Institute of Physics Inc., 2021) Chawla, S.; Larsson, S.; Huang, H.; Hegde, S.
The rolling bearing is one of the key components for the functioning of sophisticated machinery in the demanding industrial world today. For efficient and smooth operation, bearings need to sustain wear, fatigue, high loads, and sometimes, heat and harsh environments. Preceding failure analysis of the current work concluded that the recurring failure of the bearings under consideration is predominantly caused by the excessive wearing of the bearing track, and false brinelling due to harsh corrosive environment. This work, as a remedial measure, aims at enhancing the bearing life by suitably applying nitrocarburizing, a thermochemical heat treatment, to bearing parts. By heat treatment, nitrogen and carbon are diffused in hardened bearing races and rolling elements at a relatively lower temperature of 560-580 Â°C followed by controlled oxidation. Structural transformation during the process formed a compound layer at the sub-surface consisting of s-Fe2-3(N, C) and y'-Fe4(N, C) phases and a thin continuous layer of Fe3O4 on the compound layer as confirmed by X-Ray diffraction and microstructural analysis. Microhardness profile confirmed progressively declining hardness from the surface towards the core. Salt spray tests performed on the nitrocarburized parts indicated excellent corrosion-resistance properties. Â© 2021 Author(s).
Biodegradation of PEEK Piston Rings
(Elsevier Ltd, 2021) Shetty, P.; Dsilva, P.; Sondar, P.R.; Kumar, B.G.; Hegde, S.
Polyether ether ketone (PEEK) is considered a high performance thermoplastic with excellent mechanical, chemical, and thermal properties. It is generally believed that this material is chemically and biologically inert, and is used for various biomedical and industrial applications, especially in the form of fiber reinforced polymeric composites. Contrary to the general belief, the present work reports the biodegradation of PEEK piston rings that were used in a reciprocating CO2 compressor. A series of circumstantial and direct evidences were collected by following various tests and characterization methods to confirm the degradation of the piston rings by bacterial attack. The bacterial cells were extracted from the degraded piston rings, cultured in agar medium and then studied using scanning electron microscope. An experimental simulation was carried out by depositing and incubating a bacterial culture on the pristine surface of a PEEK specimen. The simulation experiment revealed an early stage of bacterial degradation in the form of cracking of the PEEK specimen surface. The results of various tests, characterization, and the experimental simulation presented in the paper suggest that PEEK based composites degrade due to enzymatic hydrolysis process by Myxococcus Xanthus, the rod–shaped soil bacteria. © 2021
Characterization of Consonant Sounds Using Features Related to Place of Articulation
(2020) Ramteke, P.B.; Hegde, S.; Koolagudi, S.G.
Speech sounds�are classified into 5 classes, grouped based on place�and manner of articulation: velar, palatal, retroflex, dental�and labial. In this paper, an attempt has been made to explore the role of place of articulation and vocal tract length in characterizing the different class of speech sounds. Formants and vocal tract length available for the production of each class of sound are extracted from the region of transition from consonant burst to the rising profile of the immediate following vowel. These features along with their statistical variations are considered for the analysis. Based on the non-linear nature of the features Random Forest (RF) is used for the classification. From the results, it is observed that the proposed features are efficient in discriminating the class of consonants: velar and palatal, palatal and retroflex and palatal and labial sounds with an accuracy of 92.9%, 93.83 and 94.07 respectively. � 2020, Springer Nature Singapore Pte Ltd.
Characterization of Consonant Sounds Using Features Related to Place of Articulation
(Springer, 2020) Ramteke, P.B.; Hegde, S.; Koolagudi, S.G.
Speech soundsÂ are classified into 5 classes, grouped based on placeÂ and manner of articulation: velar, palatal, retroflex, dentalÂ and labial. In this paper, an attempt has been made to explore the role of place of articulation and vocal tract length in characterizing the different class of speech sounds. Formants and vocal tract length available for the production of each class of sound are extracted from the region of transition from consonant burst to the rising profile of the immediate following vowel. These features along with their statistical variations are considered for the analysis. Based on the non-linear nature of the features Random Forest (RF) is used for the classification. From the results, it is observed that the proposed features are efficient in discriminating the class of consonants: velar and palatal, palatal and retroflex and palatal and labial sounds with an accuracy of 92.9%, 93.83 and 94.07 respectively. Â© 2020, Springer Nature Singapore Pte Ltd.
Comparison of creep rates of AA 5356 alloy based aluminium silicon carbide composite and AISI 316L stainless steel by indentation creep test method
(2012) Udaya Prasanna, H.U.; Rajendra Udupa, K.; Hegde, S.
[No abstract available]
Conjugate Heat Transfer Studies in a Hexagonal Micro Channel
(2015) Hegde, S.; Narendran, N.; Ganasekaran, 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.
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. Â© 2015 The Authors.
Controlled release of nutrients to mammalian cells cultured in shake flasks
(2012) Hegde, S.; Pant, T.; Pradhan, K.; Badiger, M.; Gadgil, M.
Though cell culture-based protein production processes are rarely carried out under batch mode of operation, cell line and initial process development operations are usually carried out in batch mode due to simplicity of operation in widely used scale down platforms like shake flasks. Nutrient feeding, if performed, is achieved by bolus addition of concentrated feed solution at different intervals, which leads to large transient increases in nutrient concentrations. One negative consequence is increased waste metabolite production. We have developed a hydrogel-based nutrient delivery system for continuous feeding of nutrients in scale down models like shake flasks without the need for manual feed additions or any additional infrastructure. Continuous delivery also enables maintaining nutrient concentrations at low levels, if desired. The authors demonstrate the use of these systems for continuous feeding of glucose and protein hydrolysate to a suspension Chinese Hamster Ovary (CHO) culture in a shake flask. Glucose feeding achieved using the glucose-loaded hydrogel resulted in a 23% higher integral viable cell density and an 89% lower lactate concentration at the end of the culture when compared with a bolus-feed of glucose. © 2011 American Institute of Chemical Engineers (AIChE).
Detection andÂ Categorization ofÂ DNS overÂ HTTPS Traffic Using Lightweight Feature Selection Methods andÂ Ensemble Classification Model
(Springer Science and Business Media Deutschland GmbH, 2025) Moulya, D.M.; Hegde, S.
In recent times, the adoption of DNS-over-HTTPS (DoH) has been projected as a means to secure DNS queries through encryption and shielding these communications from potential eavesdroppers via HTTPS and TLS protocols. However, this advancement is a double-edged sword as it also offers a veil for cybercriminals to execute undetected data exfiltration and command-and-control (C2) attacks. This creates a substantial challenge for network administrators who must detect malicious activities without direct visibility into the content of DoH traffic. Our research addresses this critical issue by detecting and categorizing DoH using lightweight feature selection algorithms, Mutual Information (MI) and Fisherâ€™s score to determine the most relevant features within DoH traffic. These features were then used to train Random Forest, CatBoost, and XGBoost classifiers. We adopted a layered approach: the first layer focuses on accurately detecting DoH traffic, while the second layer classifies the nature of the detected DoH traffic. A Voting-based ensemble classifier trained and tested on features identified by both algorithms achieved high accuracy rates of 99.7% in the initial layer and 100% in the second layer. Experimental results demonstrate that our model infrequently misclassifies HTTPS traffic as DoH, enhancing the reliability of our detection mechanism. In an effort to make these processes transparent, we have implemented an explainable AI framework that clarifies the decision-making pathways of our best base model. Â© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.
Dynamic blocked transfer stiffness method of characterizing the magnetic field and frequency dependent dynamic viscoelastic properties of MRE
(Korean Society of Rheology, 2016) Poojary, U.R.; Hegde, S.; Gangadharan, K.V.
Magneto rheological elastomer (MRE) is a potential resilient element for the semi active vibration isolator. MRE based isolators adapt to different frequency of vibrations arising from the source to isolate the structure over wider frequency range. The performance of MRE isolator depends on the magnetic field and frequency dependent characteristics of MRE. Present study is focused on experimentally evaluating the dynamic stiffness and loss factor of MRE through dynamic blocked transfer stiffness method. The dynamic stiffness variations of MRE exhibit strong magnetic field and mild frequency dependency. Enhancements in dynamic stiffness saturate with the increase in magnetic field and the frequency. The inconsistent variations of loss factor with the magnetic field substantiate the inability of MRE to have independent control over its damping characteristics. © 2016 The Korean Society of Rheology and Springer.
Dynamic controller placement in edge-core software defined networks
(2017) Hegde, S.; Ajayghosh, R.; Koolagudi, S.G.; Bhattacharya, S.
Software Defined Networking (SDN) is fast gaining acceptance as a networking architecture, which simplifies network management, by separating the control plane from the data plane. Edge-Core SDN is an extended SDN architecture which divides the underlying network into edge and core components. This decouples the edge switch requirements from the network core switch behaviour. When the number of networking elements and traffic flows increase, a single centralized controller can not efficiently manage, the large network nor the diverse requirements of the core and edge switches. We therefore need multiple controllers for wide area SDN deployments. Distributed controller architectures are already recommended to resolve scalability issues. The drawback of these approaches is that they use static mapping of switches to controllers. When the traffic conditions changes this static allotment may lead to unbalanced partitioning of load among the controllers. In this paper, we present controller placement algorithms for SDN, where the edge and core of the network are separated. The algorithm uses a different set of metrics for the edge and core algorithms. Also, in order to establish the Edge-Core model, we use source routing, which embeds the path information into the packet header itself. We also discusses the switch migration procedure for transfer of switch from one controller to another, such that, on going connections are not disrupted. We build a prototype of the above architecture, evaluate it and present our results here. � 2017 IEEE.
Dynamic controller placement in edge-core software defined networks
(Institute of Electrical and Electronics Engineers Inc., 2017) Hegde, S.; Ajayghosh, R.; Koolagudi, S.G.; Bhattacharya, S.
Software Defined Networking (SDN) is fast gaining acceptance as a networking architecture, which simplifies network management, by separating the control plane from the data plane. Edge-Core SDN is an extended SDN architecture which divides the underlying network into edge and core components. This decouples the edge switch requirements from the network core switch behaviour. When the number of networking elements and traffic flows increase, a single centralized controller can not efficiently manage, the large network nor the diverse requirements of the core and edge switches. We therefore need multiple controllers for wide area SDN deployments. Distributed controller architectures are already recommended to resolve scalability issues. The drawback of these approaches is that they use static mapping of switches to controllers. When the traffic conditions changes this static allotment may lead to unbalanced partitioning of load among the controllers. In this paper, we present controller placement algorithms for SDN, where the edge and core of the network are separated. The algorithm uses a different set of metrics for the edge and core algorithms. Also, in order to establish the Edge-Core model, we use source routing, which embeds the path information into the packet header itself. We also discusses the switch migration procedure for transfer of switch from one controller to another, such that, on going connections are not disrupted. We build a prototype of the above architecture, evaluate it and present our results here. Â© 2017 IEEE.