Faculty Publications
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Publications by NITK Faculty
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Item Development of scheduler for real time and embedded system domain(2008) Rao, M.V.P.; Shet, K.C.; Balakrishna, R.; Roopa, K.We discuss scheduling techniques to be used for real-time, embedded systems. Though there are several scheduling policies, the preemptive scheduling policy holds promising results. In this research paper, the different approaches to design of a scheduler for real-time Linux kernel are discussed in detail. The comparison of different preemptive scheduling algorithms is performed. Hence, by extracting the positive characteristics of each of these preemptive scheduling policies, a new hierarchical scheduling policy is developed. The proposed hierarchical scheduling for real time and embedded system will be implemented for a prototype system, using C or C++ language. It is expected that the new scheduling algorithm will give better performance with respect to satisfy the needs, such as time, capturing and usage of resources of different applications. © 2008 IEEE.Item Development of a digital excitation system for synchronous generator on RTAI-Linux platform(2012) Deepak, M.; Shubhanga, K.N.In this paper realization of a digital excitation system for synchronous generator is discussed. Such a real-time task is implemented using Real-Time Application Interface on Linux platform which is an open source effort. In this work a static excitation system is considered which involved the development of additional hardware circuits such as fully-controlled thyristor bridge-rectifier, the associated firing circuit module and data acquisition systems. In addition to normally discussed proportional controller, a proportional-integral controller is also realized to understand its generator voltage regulation performance under different operating conditions. Case studies are presented related to both standalone and parallel operation conditions of the generator without taking up complex controller-tuning procedures. Such a setup is found to augment the generally employed simulation-based power system dynamics analysis. © 2012 IEEE.Item Implementation and characterization of a numerical distance relay using a relay test-bench on RTAI-Linux platform(2013) Padmasali, A.; Amoghimath, K.; Hazarika, P.P.; Shetty, P.K.; Shubhanga, K.N.This paper deals with the implementation, evaluation and characterization of a numerical distance relay using a laboratory relay test-bench implemented on real-time application interface (RTAI)-Linux platform. The numerical distance relay has been realized on RTAI-Linux platform based on the full-cycle recursive discrete Fourier series algorithm. This relay provides a selectable relay characteristic such as Mho or Quadrilateral or Elliptical characteristic. The relay test-bench not only can be used to obtain steady-state relay characteristics, but also facilitates to generate any fault signals to perform dynamic testing of the relays. In this paper, Mho and Quadrilateral type numerical relay characteristics have been chosen for demonstration. It is found that such an experimental setup provides a hardware-in-the-loop facility in the lab environment to enhance the understanding about protective systems and thereby augmenting the classroom learning. © 2013 IEEE.Item Hardware-In-The-Loop testing of PSS for synchronous generator(Institute of Electrical and Electronics Engineers Inc., 2014) Latha, A.H.; Shubhanga, K.N.This paper presents the Hardware-In-The-Loop type simulation, where an analog power system stabilizer (PSS) is connected in closed loop with a real-time virtual synchronous generator. The synchronous generator along with its excitation controller is simulated in real-time using Real-Time Application Interface (RTAI) on Linux. Forward Euler numerical integration technique with a suitable step-size has been employed for obtaining the solution of the generator model differential equations. The PSS hardware is interfaced with the virtual synchronous generator using a peripheral component interconnect (PCI) card and the simulation results are captured on the oscilloscope. The real-time simulations are also validated using off-line MATLAB simulations. This setup demonstrates different aspects of realtime simulation and a laboratory-oriented Hardware-In-The-Loop simulation. © 2014 IEEE.Item Revisiting design choices in queue disciplines: The PIE case(Elsevier B.V., 2020) Imputato, P.; Avallone, S.; Tahiliani, M.P.; Ramakrishnan, G.Bloated buffers in the Internet add significant queuing delays and have a direct impact on the user perceived latency. There has been an active interest in addressing the problem of rising queue delays by designing easy-to-deploy and efficient Active Queue Management (AQM) algorithms for bottleneck devices. The real deployment of AQM algorithms is a complex task because the efficiency of every algorithm depends on appropriate setting of its parameters. Hence, the design of AQM algorithms is usually entrusted on simulation environments where it is relatively straightforward to evaluate the algorithms with different parameter configurations. Unfortunately, several factors that affect the efficiency of AQM algorithms in real deployment do not manifest during simulations, and therefore, lead to inefficient design of the AQM algorithm. In this paper, we revisit the design considerations of Proportional Integral controller Enhanced (PIE), an algorithm widely considered for network deployment, and extensively evaluate its performance using a Linux based testbed. Our experimental study reveals some performance anomalies in certain circumstances and we prove that they can be attributed to a specific design choice of PIE, namely the use of the estimated departure rate to compute the expected queuing delay. Therefore, we designed an alternative approach based on packet timestamps, implemented it in the Linux kernel and proved its effectiveness through an experimental campaign. © 2020