Indian Institute of Technology Guwahati

About: Indian Institute of Technology Guwahati is a education organization based out in Guwahati, Assam, India. It is known for research contribution in the topics: Adsorption & Catalysis. The organization has 6933 authors who have published 17102 publications receiving 257351 citations.

Distance Adaptive Dynamic Routing and Spectrum Allocation in Elastic Optical Networks With Shared Backup Path Protection

Abstract: This paper considers distance adaptive dynamic routing and spectrum assignment (RSA) for elastic optical networks with shared backup path protection (SBPP). Efficient heuristic algorithms based on spectrum window planes are proposed for implementing distance and modulation format adaptive RSA so as to maximize spare capacity sharing among multiple protection lightpaths. A differentiated sharable frequency slot cost was also defined for the first time to more efficiently share protection resource. Network performance is evaluated in terms of bandwidth blocking probability (BBP) through simulations. The proposed SBPP technique is effective in reducing BBP and improving spectral efficiency compared to conventional SBPP schemes and 1+1 path protection. The impact of transponder tunability on bandwidth blocking performance is also evaluated to show that a limited tuning range is sufficient to achieve a BBP performance close to that with full tunability.

Kinetic and Equilibrium Studies on the Adsorption of Crystal Violet Dye using Kaolin as an Adsorbent

Abstract: Experimental investigations are carried out to adsorb toxic crystal violet dye from aqueous medium using kaolin as an adsorbent. Characterization of kaolin is done by measuring particle size distribution using particle size analyzer, BET surface area using BET surface analyzer, structural analysis using X ray diffractometer, and microscopic analysis using scanning electron microscope. The effects of initial dye concentration, contact time, kaolin dose, stirring speed, pH, and temperature are studied for the adsorption of crystal violet in batch mode. Adsorption experiments indicate that the extent of adsorption is strongly dependent on the pH of the solution. Free energy of adsorption (ΔG o ), enthalpy (ΔH o ), and entropy (ΔS o ) changes are calculated to know the nature of adsorption. The calculated values of ΔG o are −4.11 and −4.48 kJ/mol at 295 K and 323 K, respectively, for 20 mg/L of dye concentration, which indicates that the adsorption process is spontaneous. The estimated values of ΔH o...

Capacitated Next Controller Placement in Software Defined Networks

Abstract: Software defined networking shifts the control plane of forwarding devices to one or more external entities known as controllers. Determining the optimal location of controllers in the network and the assignment of switches to them is widely known as controller placement problem. In case of controller failures, the switches are disconnected from the controller until they are reassigned to other active controllers with enough spare capacity. However, there is a significant upsurge in the worst case latency after the reassignment due to lack of planning for controller failures. In this paper, we propose a controller placement strategy that not only considers reliability and capacity of controllers but also plans ahead for controller failures to avoid repeated administrative intervention, drastic increase in latency and disconnections. It is formulated as a mixed integer linear program. The objective is to minimize the maximum, for all switches, of the sum of the latency from the switch to the nearest controller with enough capacity (first reference controller) and the latency from the first reference controller to its closest controller with enough capacity (second reference controller). We also proposed a generalized model which can be used to minimize the average latency and extended it for multiple controller failures. Furthermore, we presented a simulated annealing heuristic that efficiently solves the problem on large scale networks. The proposed formulation and heuristic are evaluated on various networks from the Internet Topology Zoo. Simulation results show that our proposed method performs better than the controller placement that does not plan ahead for failures.