Faculty Publications
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Publications by NITK Faculty
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Item Studies on esters of coconut oil as fuel for LPG-Biodiesel dual fuel engine(American Society of Mechanical Engineers Three Park Avenue New York NY 10016-5990, 2003) Kapilan, N.; Reddy, R.P.; Mohanan, P.The rapid depletion in world petroleum reserves and uncertainty in petroleum supply due to political and economical reasons, as well as, the sharp escalation in the petroleum prices, have stimulated the search for alternatives to petroleum based fuels specially diesel and gasoline. Biodiesel is one of the renewable fuels, which will be the good replacement to diesel. But as a sole fuel, it gives poor performance and higher emissions. From the literature survey, it is observed that not much work has been done to use Methyl Ester (ME) of coconut oil as liquid fuel in sole and dual fuel mode of operation. Hence, in the present work, ME of coconut oil is chosen as a sole fuel to run the diesel engine and an alternative pilot fuel to run LPG-Biodiesel dual fuel engine. In dual fuel mode operation, LPG is used as the inducted gaseous fuel. LPG has been chosen as the inducted fuel on account of its easy availability in abundance in the present time. The existing compression ignition diesel engine was modified to work on dual fuel mode. Tests were carried out on a single cylinder, four strokes, water-cooled, direct injection, compression ignition engine using ME of coconut oil as fuel. To study the effect of injection timing, its is advanced and retarded from the standard injection timing recommended for diesel operation. From the results, it is observed that the advanced injection timing results in better performance and lower emissions of the diesel engine. In dual fuel mode operation, first the engine was started with ME of coconut oil as fuel and then the LPG flow rate was increased. With appropriate proportions of the injected (0.45, 0.65 and 0.75 kg/hr) and inducted fuels it is possible to improve the engine performance and reduce its emissions. From the experimental results, it is found that the pilot fuel rate of 0.65 kg/hr is preferred from the point view of brake thermal efficiency, fuel consumption and smooth running. ME of coconut oil were successfully used as sole fuel and pilot fuel. The performance and emission of the engine in sole fuel mode with better injection timing and dual fuel mode with better pilot quantity were compared. From the comparison, it is observed that the ME of coconut oil can be used as pilot fuel in dual fuel engine compared to sole fuel with regard to performance and emissions.Item Search improvement in unstructured P2P network considering type of content(2008) Totekar, C.R.; Vani, M.; Palavalli, S.R.One of the key challenging aspects of peer-to-peer systems has been efficient search for objects. To achieve this, we need to minimize the number of nodes that have to be searched, thereby use minimum number of messages during the search process. This can be done by selectively sending requests to nodes having higher probability of a hit for the queried object. In this paper we present an algorithm CBWS, for searching in unstructured peer-to-peer network, which is based on the fact that most users in peer-to-peer network share various types of data(e.g. audio, video, text, archive) in different proportions. The information about the number of objects of each file-type shared by nodes, is used to selectively forward the query to a node having higher hit-ratio for the data objects of requested type, based on the history of recently succeeded queries. Simulation results prove that our searching algorithm performs better than the selective walk searching algorithm.Item Performance analysis of AODV, AODVUU, AOMDV and RAODV over IEEE 802.15.4 in wireless sensor networks(2009) Gowrishankar, S.; Sarkar, S.K.; Basavaraju, T.G.In this paper the focus is on the performance study of four routing protocols, namely AODV, AODVUU, RAODV and AOMDV. We call these protocols AODV family of protocols as all these protocols consider AODV as the base routing protocol upon which these protocols are improved. Even though AODV and AODVUU are not different protocols, we wanted to see if there is any improvement in using the AODVUU implementation for a sensor network environment. We have investigated whether a multiple path algorithm like AOMDV would result in more data delivery as compared to single path solutions like AODV in a sensor network. Also, the reverse route discovery mechanisms employed in RAODV is checked for a sensor network. There is a need to understand the versatile behavioral aspects of these routing protocols in a wireless sensor network with varying traffic loads and the number of sources. All these protocols are simulated using NS- 2 over IEEE 802.15.4. We also claim that our work is the first of its kind to study and compare the performance of all these four routing protocols from a sensor network point of view by extensively using various performance metrics like packet delivery ratio, average network delay, network throughput and normalized routing load. © 2009 IEEE.Item Performance and emission studies of a LPG fueled spark ignition engine with steam induction(Korean Society of Combustion, 2013) Shankar, K.S.; Mohanan, P.In this study the combustion and emission characteristics of a conventional naturally aspirated, four-cylinder, multipoint port fuel injection S.I engine modified to run with liquefied petroleum gas (LPG) injection along with steam induction are evaluated. Experiments are conducted at wide-open throttle condition and at a speed range of 2000 rpm to 4500 rpm with a static ignition timing of 6-degree bTDC. The steam flow rates of 10 to 25% of LPG flow rates (by mass) are used. The results with LPG and 25% steam induction at wide-open throttle condition and 3500 rpm indicates that the brake thermal efficiency has reduced by 2%, and the peak cylinder pressure has reduced by about 10 bar, with the location of the peak pressure being way from top dead centre when compared to LPG combustion. Oxides of nitrogen emission has reduced significantly with the induction of steam with a reduction of 45% when compared to LPG at 3500 rpm. The carbon monoxide and unburnt hydrocarbon emissions at the above condition have increased marginally. Thus the induction of steam along with LPG has resulted in notable reduction in the oxides of nitrogen emissions with a slight reduction in engine performance.Item Experimental analysis of cardanol biofuel as an alternative fuel for diesel engines with air-side oxygen enrichment(Trans Tech Publications Ltd ttp@transtec.ch, 2014) Dinesha, P.; Nayak, V.; Kumar, D.; Mohanan, P.The present study investigates the effect of air-side oxygen concentration enrichment on the performance and emission of a single cylinder diesel engine using a bio-fuel blend as fuel. In this study, a natural phenolic compound, namely, cardanol is selected as the bio-fuel, which is obtained from the shell of cashew nut after purification. A blend of B10M10 (10% cardanol +10% methanol + 80% diesel by volume) is prepared and tested in the engine at various loading conditions. The experiments are carried out at atmospheric oxygen condition and an increment of 3, 5, and 7% of atmospheric oxygen concentration by weight. There is a drastic reduction in HC, CO, and smoke except for NOx emission. The level of NOx emission increases as the oxygen concentration in the intake air is increased. The performance characteristic will increase as the oxygen concentration increases, and higher brake thermal efficiency is obtained for B10M10 at 7% oxygen concentration. B10M10 with 7% oxygen enrichment gives better results, similar to diesel, except for NOx emission. © (2014) Trans Tech Publications, Switzerland.Item Predicting an optimal sparse matrix format for SpMV computation on GPU(IEEE Computer Society help@computer.org, 2014) Bayyapu, B.; Guddeti, G.R.M.; Raghavendra, P.S.Many-threaded architecture based Graphics Processing Units (GPUs) are good for general purpose computations for achieving high performance. The processor has latency hiding mechanism through which it hides the memory access time in such a way that when one warp (group of 32 threads) is computing, the other warps perform memory bound access. But for memory access bound irregular applications such as Sparse Matrix Vector Multiplication (SpMV), memory access times are high and hence improving the performance of such applications on GPU is a challenging research issue. Further, optimizing SpMV time on GPU is an important task for iterative applications like jacobi and conjugate gradient. However, there is a need to consider the overheads caused while computing SpMV on GPU. Transforming the input matrix to a desired format and communicating the data from CPU to GPU are non-trivial overheads associated with SpMV computation on GPU. If the chosen format is not suitable for the given input sparse matrix then desired performance improvements cannot be achieved. Motivated by this observation, this paper proposes a method to chose an optimal sparse matrix format, focusing on the applications where CPU to GPU communication time and pre-processing time are nontrivial. The experimental results show that the predicted format by the model matches with that of the actual high performing format when total SpMV time in terms of pre-processing time, CPU to GPU communication time and SpMV computation time on GPU, is taken into account. The model predicts an optimal format for any given input sparse matrix with a very small overhead of prediction within an application. Compared to the format to achieve high performance only on GPU, our approach is more comprehensive and valuable. This paper also proposes to use a communication and pre-processing overhead optimizing sparse matrix format to be used when these overheads are non trivial. © 2014 IEEE.Item O3 - A webpage preprocessing tool(SciTePress, 2015) Senthil, K.; Bhat, K.S.; Jamadagni, N.; Sureshan, S.; Prasad, G.One of the prime factors for the success of the internet is determined by the time taken to load a web page. Even a difference of a few hundred milliseconds in the response time will largely affect the number of users of a web page to shift from one to the other. So, in the commercial market, providing quick service to the users is of utmost importance in remaining ahead of competitors. In this paper, we mainly address this issue by applying various optimization techniques at the front-end to improve the user experience by reducing the load time of the web pages. Though the overall optimization is purely web page-dependent, the optimization techniques not only reduce the time taken to load the page, but also reduce the load on the server.Item Workload Characterization: Survey of Current Approaches and Research Challenges(Association for Computing Machinery acmhelp@acm.org, 2017) Shishira, S.R.; Kandasamy, A.; Chandrasekaran, K.Workload is a set of inputs given to a infrastructure for processing. Performance can be measured based on the efficient processing of the workloads. Different workloads has different set of characteristics. In this paper, we have mainly focused on cloud workloads. Understanding the characteristics of workloads is the key to make an optimal configuration decisions and improve the system performance. This paper describes various computing workloads and relates them to their resource utilization. Specifically, the paper concentrates on cloud workloads characterization. We have classified the workloads based on different aspects from the literature also we have provided the characteristic features of the workload to know the properties and make it more understandable for the researchers. © 2017 Association for Computing Machinery.Item Performance Emission and Combustion Characteristics of CRDI Engine Operating on Jatropha Curcas Blend with EGR(Elsevier Ltd, 2018) Bedar, P.; Kumar, G.N.The present experimental study uses dual cylinder common rail direct injection (CRDI) engine fuelled by Jatropha curcas biodiesel blends produced through Transesterification process along with application of water cooled exhaust gas recirculation (EGR) rates. Performance, emissions and combustion properties of an engine at constant speed were measured and analysed. The improvement in brake thermal efficiency (BTE) along with reduction in carbon monoxide (CO), unburned hydrocarbons (UBHC) and smoke opacity were observed for the B20 biodiesel blend with a marginal increase in oxides of nitrogen (NOx). EGR application has reduced the NOx emissions and peak pressure inside the combustion chamber due to lower flame temperature. Combining B20 blend ratio with 15% EGR rate has the potential to achieve ultra-low NOx without affecting other type of diesel engine exhaust emissions by maintaining same efficiency level. © 2018 Elsevier Ltd.Item Parallel OpenMP and CUDA Implementations of the N-Body Problem(Springer Verlag service@springer.de, 2019) Gangavarapu, T.; Pal, H.; Prakash, P.; Hegde, S.; Geetha, V.The N-body problem, in the field of astrophysics, predicts the movements of the planets and their gravitational interactions. This paper aims at developing efficient and high-performance implementations of two versions of the N-body problem. Adaptive tree structures are widely used in N-body simulations. Building and storing the tree and the need for work-load balancing pose significant challenges in high-performance implementations. Our implementations use various cores in CPU and GPU via efficient work-load balancing with data and task parallelization. The contributions include OpenMP and Nvidia CUDA implementations to parallelize force computation and mass distribution, and achieve competitive performance in terms of speedup and running time which is empirically justified and graphed. This research not only aids as an alternative to complex simulations but also to other big data applications requiring work-load distribution and computationally expensive procedures. © 2019, Springer Nature Switzerland AG.