Browsing by Author "Rao, S."
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Item A laboratory investigation on a single row of suspended porous pipes is conducted in a two-dimensional wave flume to study their hydraulic performance under regular wave attack. The wave energy losses are computed and the effects of porosity, water depth, incident wave steepness and relative wave height on loss coefficient are studied. It is found that loss coefficient increases with an increase in incident wave steepness. Water depth has insignificant effect on K1 when wave steepness is varied. It is also observed that as porosity increases K1 decreases. For the range of variables studied, as the relative wave height increases, K1 decreases.(Energy dissipation in suspended porous pipe breakwaters in laboratory) Rao, S.; Rao, N.B.S.; Shirlal, K.G.2003Item A laboratory investigation on a single row of suspended porous pipes was conducted in a two-dimensional regular wave flume to study their hydraulic performance. The wave energy losses at the structure were computed and the effects of depth of submergence, incident wave steepness, water depth, pipe diameter, percentage of perforations, size of perforations and relative wave height on loss coefficient were studied. It was found that as incident wave steepness increases, loss coefficient K 1 increases. Water depth has insignificant effect on K 1. It is also observed that as percentage of perforations increases, K 1 increases. For the range of variables studied, as the relative wave height increases, K 1 decreases.(Energy dissipation at single row of suspended perforated pipe breakwaters) Rao, S.; Rao, N.B.S.; Shirlal, K.G.; Guddeti, G.R.2003Item A laboratory investigation on perforated hollow piles in two rows was conducted in a two dimensional regular wave flume to study the wave transmission and reflection characteristics. The influence of incident wave steepness, relative clear spacing between the piles and rows of piles on transmission co-efficient and reflection co-efficient have been investigated. The effect of staggering of piles in the rows on both transmission and reflection co-efficients was also studied. The present study has revealed that for perforated pile groups incident wave steepness, relative clear spacing between the piles, relative clear spacing between the rows of piles influence both transmission and reflection co-efficients. Staggering of piles reduces reflection from the perforated piles. Perforated piles have smaller transmission and reflection co-efficient values compared to that of non-perforated piles at lower wave steepness.(Wave transmission and reflection for two rows of perforated hollow piles) Rao, S.; Shirlal, K.G.; Rao, N.B.S.2002Item A laboratory investigation on single row suspended porous pipes was conducted in a two-dimensional regular wave flume to study their hydraulic performance. The effects of porosity, water depth, incident wave steepness and relative wave height on transmission and reflection coefficients were studied. It was found that (a) as incident wave steepness increases transmission coefficient Kt decreases and reflection coefficient Kt increases; (b) water depth has insignificant effect on Kt and Kt for porous pipes; (c) as porosity decreases Kt decreases and Kt increases; and (d) the range of variables studied, as the relative wave height increases Kt increases and Kr decreases.(Performance of single row of suspended porous pipe breakwater) Rao, S.; Rao, N.B.S.; Reddy, Y.V.B.2001Item A laboratory investigation on the suspended perforated hollow cylinders in a single row was conducted in a two-dimensional wave flume, to study their hydraulic performance. The influence of depth of submergence, size of pipes, percentage of perforations and water depth on wave reflection characteristics have been investigated. From the investigation it was found that, as the relative depth of submergence increases, reflection increases. Water depth has insignificant effect on reflection coefficient Kr. The reflection coefficient Kr increases as incident wave steepness increases. For perforated pipes, size of the pipe has negligible effect on Kr. Wave period alone does not directly influence the reflection. © 1999 Taylor & Francis Group, LLC.(Laboratory investigation on wave reflection characteristics of suspended perforated pipe breakwater) Rao, S.; Rao, N.B.S.1999Item A Review on Stability of Caisson Breakwater(Springer Nature, 2018) Gedda, A.B.; Rao, M.; Rao, S.A Breakwater can be designed for several different purposes; the basic function of such kind breakwater is to protect the water region against waves. It provides a tranquility condition for ships to navigate, moor, and for cargo handling. These vertical structures (caisson) are more economical compared to the rubble mound breakwater, especially in deeper water depths. There is a demand to expand existing ports or to make them more profound, to provide a sufficient tranquil harbor basin in deep-water due to increasing draught of large vessels. The material required for rubble mound breakwaters increase quadratic with depth, but the volume of the caisson is less than that needed for a rubble mound breakwater because the latter increases with the square of water depth. This paper concerned the previous design and failure mechanism on caisson breakwater and highlights the future studies for such kind of breakwater. © Springer Nature Singapore Pte Ltd. 2019.Item A survey and comparison of GTS allocation and scheduling algorithms in IEEE 802.15.4 wireless sensor networks(2013) Rao, S.; Keshri, S.; Gangwar, D.; Sundar, P.; Geetha, V.Multimedia applications in the wireless domain require not only contention-based communication, but also reservation based one. The IEEE 802.15.4 standard is widely used for Wireless Sensor Networks (WSNs), and is a standard for low rate, low power and low cost WPANs (Wireless Personal Area Networks). Moreover, it supports the allocation of Guaranteed Time Slot (GTS) to the devices in Contention free period (CFP). With time, many GTS scheduling and allocation algorithms have been proposed with the aim to make maximum the use of GTS. This paper provides a survey and comparison on the current state-of-the-art researches in this important area. We have firstly summarized all the important algorithms proposed till now and then classified and compared them based on various parameters including type, delay, bandwidth, cost, topology, traffic and energy efficiency. © 2013 IEEE.Item Alternate Approaches to Scattering Networks in Image Classification(Institute of Electrical and Electronics Engineers Inc., 2023) Rao, S.; Varma, V.Scattering networks are a special class of convolutional neural networks (CNNs) which implement a windowed scattering transform in their initial layers while learning the rest of the parameters. For classification tasks requiring little data, scattering networks beat cutting-edge deep neural networks. When given a huge dataset, their performance is comparable to end-to-end trained networks, but they're better suited for real-time applications due to their lower latency. The use of a windowed scattering transform for tasks involving image classification on the CIFAR-10 dataset is examined in this paper. We replace the 2-D Gabor filterbank in the state-of-the-art scattering network with alternate filterbanks that provide better directional separation in the frequency domain. We also develop a trainable directional filterbank that uses data-driven directional filters in its construction. The directional filters are built using the weights of a 2D convolutional operator. We demonstrate the performance of the alternate approaches in supervised classification tasks and observe that the trainable implementation outperforms the traditional scattering networks. © 2023 IEEE.Item Analysis of berthing structures for wave induced forces(2011) Shanthala, B.; Rao, S.; Venkataramana, K.; Narayana, H.Countries surrounded by ocean can easily achieve tremendous progress in trade and industry provided proper planning of ports and harbours is made for transportation of goods and materials through sea transport. Berthing structures are to be designed for different load combinations. The deck of berthing structure is generally supported by vertical piles. Marine and offshore structures are subjected to wave and current forces and the loads acting on the member are cyclic and will induce time varying forces and moments. Due to this nature of wave forces and moments, the stress in the structure material fluctuates with respect to time, leading to progressive growth of cracks and they ultimately lead to fracture. This fatigue changes depends upon the wave action. To reduce wave and berthing forces, it is important to fix the alignment in such a way that incoming forces are minimum. Berthing structures are the facilities constructed in ports for berthing and mooring of vessels, for loading and unloading of cargo and for embarkment and disembarkment of passengers or vehicles. The berthing structures are designed for dead load, live load, berthing force, mooring force, earthquake load and other environmental loading due to winds, waves, currents etc,. In the present study layout of jetty for berthing 5000 DWT ship at NMPT is modeled using the ship dimensions from IS code and analyzed for the available environmental data from NMPT using StruCAD 3D software. The detailed analysis of the berthing structure for the significant wave height of 3.2m is carried out for a full cycle of wave and the Variation of deflection, forces and moments for perpendicular wave directions and different pile diameters is done by Static and Dynamic analysis. Dynamic Amplification Factor is calculated by comparing static and dynamic analysis results. Time history analysis is also done for the wave loading and deflection, forces and moments of the structure is calculated. From the results it is observed that the forces and moments are large as the diameter of pile increases and the deflection is reduced. From the time history analysis it is observed that as the pile diameter increases the maximum deflection occurs at the larger time period. It was found that at time period of 8.611sec peak response occurs. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Application of neural network for the prediction of tensile properties of friction stir welded composites(2017) Shettigar, A.K.; Prabhu, S.; Malghan, R.; Rao, S.; Herbert, M.In this paper, an attempt has been made to apply the neural network (NN) techniques to predict the mechanical properties of friction stir welded composite materials. Nowadays, friction stri welding of composites are predominatally used in aerospace, automobile and shipbuilding applications. The welding process parameters like rotational speed, welding speed, tool pin profile and type of material play a foremost role in determining the weld strength of the base material. An error back propagation algorithm based model is developed to map the input and output relation of friction stir welded composite material. The proposed model is able to predict the joint strength with minimum error. � 2017 Trans Tech Publications, Switzerland.Item Application of response surface methodology and enhanced non- Dominated sorting genetic algorithm for optimisation of grinding process(2013) Pai, D.; Rao, S.; D'Souza, R.Optimisation of grinding process during grinding of A16061-SiC composites is investigated in this study. Stir cast A16061-SiC composites with varying volume percentage of SiC reinforcement were ground on a conventional grinding machine with diamond grit grinding wheel. Three grinding variables were studied for simultaneous optimization of material removal rate and surface roughness. Initially, the response surface models for grinding process parameters were developed using response surface methodology. Further, the developed models were optimized using enhanced elitist non-dominated sorting genetic algorithm (enhanced NSGA-II), a time saving algorithm in comparison to conventional NSGA-II. The suitable grinding conditions for multi-objective optimization of the grinding process were obtained from enhanced NSGA-II. Finally the confirmation tests were performed to validate the results obtained from response surface methodology and enhanced NSGA-II. It is observed that, experimental results and the results obtained from enhanced NSGA-II are in close conformance. Hence it is concluded that the developed algorithm can effectively be used for optimization of grinding process. � 2013 The Authors. Published by Elsevier Ltd.Item Application of response surface methodology and enhanced non- Dominated sorting genetic algorithm for optimisation of grinding process(Elsevier Ltd, 2013) Dayananda Pai, D.; Rao, S.; D'Souza, R.Optimisation of grinding process during grinding of A16061-SiC composites is investigated in this study. Stir cast A16061-SiC composites with varying volume percentage of SiC reinforcement were ground on a conventional grinding machine with diamond grit grinding wheel. Three grinding variables were studied for simultaneous optimization of material removal rate and surface roughness. Initially, the response surface models for grinding process parameters were developed using response surface methodology. Further, the developed models were optimized using enhanced elitist non-dominated sorting genetic algorithm (enhanced NSGA-II), a time saving algorithm in comparison to conventional NSGA-II. The suitable grinding conditions for multi-objective optimization of the grinding process were obtained from enhanced NSGA-II. Finally the confirmation tests were performed to validate the results obtained from response surface methodology and enhanced NSGA-II. It is observed that, experimental results and the results obtained from enhanced NSGA-II are in close conformance. Hence it is concluded that the developed algorithm can effectively be used for optimization of grinding process. © 2013 The Authors. Published by Elsevier Ltd.Item Areca nut husk biochar as a sustainable carbonaceous filler for cement: Pyrolysis temperature and its effect on characterization, strength, and hydration(Elsevier B.V., 2024) Manjunath, B.; Ouellet-Plamondon, C.M.; Das, B.B.; Rao, S.; Bhojaraju, C.; Rao, M.This study addresses the gap in sustainable agro-based materials for cement by exploring locally available areca nut husk pyrolyzed into areca nut husk biochar (AB). The research investigated the effect of pyrolysis temperature (300°C, 400°C, and 500°C) on the characteristics of AB and its impact on cementitious performance. The study found that increasing pyrolysis temperatures led to lower yield, greater aromaticity, and increased surface area of AB. Fourier Transform Infrared Spectroscopy (FTIR) analysis showed decreased functional groups in AB at higher temperatures, confirming enhanced carbonization. Thermogravimetric analysis (TGA) revealed greater thermal stability of AB. X-ray diffraction (XRD) indicated a carbon-rich amorphous structure and crystalline graphite carbon formation in AB. Incorporating AB at 2 % into cementitious composites substantially increased the compressive strength compared to the control mortar. At 7 and 28 days, the compressive strength increased by 8 % and 12 % for AB 300, 16 % and 21 % for AB 400, and 27 % and 34 % for AB 500. This improvement was due to the micro filler effect of AB, which improved the compactness of the cementitious matrix. Hydration studies from TGA showed that the addition of AB accelerated early-stage hydration, with the degree of hydration increasing from 46 % (in control mix) to 48–53 % in AB blended mixes using Bhatty's method. FTIR analysis demonstrated improved hydration of silicate phases and C-S-H formation in the presence of AB, supported by XRD analysis. AB blended mortar reduced the CO2 equivalent emission by 22 % compared to the control mortar attributed to its carbon sequestration capacity. These results highlight the potential of AB as a sustainable carbonaceous filler for cementitious composites, offering an environmentally friendly option for future research in construction materials. © 2024 Elsevier B.V.Item Assessment of dynamic pressure and wave forces on vertical-caisson type breakwater(Taylor and Francis Ltd., 2022) Kumaran, V.; Rao, M.; Rao, S.The design and construction of coastal structures such as breakwaters, at great water depths is rapidly increasing as a result of the increasing draught of large vessels and off-shore land reclamations. Vertical caisson breakwaters may be the best alternative compared to ordinary rubble mound breakwaters in larger water depths, in terms of performance, total costs, environmental aspects, construction time and maintenance. To fulfilling the functional utility and impact of the structure on the sea environment, it is necessary to study the hydraulic performance. This can be found by field investigation, numerical simulations and by physical modelling. Scale modelling techniques are used to study various coastal engineering problems. This article presents the results obtained by conducting series of experiments in two-dimensional wave flume to assess the hydrodynamic performance of vertical-caisson breakwater, which is made of concrete, with the protection of toe. The dynamic pressure distribution, wave runup, wave reflection, wave forces and stability parameter on the vertical caisson breakwater are discussed. The maximum wave force on the wall breakwater is calculated from measured pressure values and is compared with the forces calculated by Goda’s and Sainflou wave theories. © 2021 Informa UK Limited, trading as Taylor & Francis Group.Item Assessment Of Wave Overtopping Discharge at Quarter Circle Breakwater Using Soft Computing Techniques(Universidad de Cantabria, 2024) Mane, V.; Shankara Krishna, A.; Rao, M.; Rao, S.The precise prediction of wave overtopping (WO) discharge is crucial for the design of coastal protection structures, particularly in light of the challenges posed by climate change. This study focuses on a quarter-circle breakwater (QBW) comprising a vertical back wall, a horizontal base slab on a rubble mound foundation, and a quarter-circle front wall facing incident waves. Utilizing Support Vector Machine (SVM) and Least Square Support Vector Machine (LSSVM), the research aims to estimate the mean overtopping discharge at the QBW. Input parameters, including incident wave steepness (Hi/gT2), depth parameter (d/gT2), percentage of perforations (p), and crest height parameter (Rc/Hi), are employed, with mean overtopping discharge (q/gHi T) as the output. Model performance is assessed using indicators such as Root Mean Square Error (RMSE), Correlation Coefficient (CC), Scatter Index (SI), and Index of Agreement (d). Results suggest that both SVM and LSSVM are effective in estimating mean overtopping discharge, with LSSVM demonstrating superior accuracy compared to SVM. The study findings contribute valuable insights for coastal engineering, particularly in designing structures resilient to wave overtopping amid ongoing climate change effects. © SEECMAR | All rights reserved.Item Assessment of wind and wave energy potential along the Indian coast(Cogent OA, 2024) Upadhyaya, S.; Rao, S.; Rao, M.The focus is now on sustainable development, which is inevitable without harnessing renewable energy sources. The fundamental element in wind wave generation is the interaction between air and sea which helps in momentum exchange between atmosphere and ocean. The Indian coastline is under a dynamic wave climate with the action of wind. Indian landmass has two tropical basins, the Bay of Bengal and the Arabian Sea, which have tremendous potential to tap renewable energy. The variations in wave climate due to dynamic-wind have to be assessed. Hindcast data obtained from Global Climate Models help us in the long-term analysis of wind and wave climate. In an attempt to explore the renewable energy potential along the Indian coast, a numerical wave model is developed using MIKE 21 SW module to assess the wind and wave climate. A gridded global wind speed dataset from ECMWF called ERA-Interim wind speed data of 38 years (1981 to 2018) is used as input for the numerical model. The dataset and numerical model performance were validated against in-situ measurements. The results showed amongst the locations studied off Goa, Karnataka, Kerala, Tamil Nadu, and Andhra Pradesh had good potential to extract offshore wind energy using offshore wind turbines. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Item Classification of tidal inlets along the central east coast of India(2015) Reddy, N.A.; Vikas, M.; Rao, S.; Seelam, J.K.Coastal inlets are the openings along the coastline that provide a linkage between the open ocean and the hinterland water bodies. These coastal inlets are varied in nature depending on many influencing parameters such as tide, wind, river flow and waves. Amongst these parameters, the tides are the most regular while waves and freshwater flow are more seasonal. The tidal inlets have to be examined and studied to understand the nearshore coastal processes. The inlet remains stable (i.e. open) as long as the alongshore sediment bypasses the tidal inlet. Classification of coastal systems in a broader view is necessary for the management of tidal inlets. There are several methods to classify tidal inlets based on different perspectives namely geo-morphological, hydrodynamic etc. In the present study, tidal inlet classification is carried out considering the hydrodynamics and morphodynamics along the Andhra Pradesh coast, considering the classification method as in Hayes (1984) and Thuy (2013). The Hayes (1984) classification considers only the tidal range and significant wave height, whereas Thuy (2013) considers discharge due to tide (?Tidal prism/tide duration) and wave (??gH5). A total of 108 tidal inlets along Andhra Pradesh coast on the east coast of India are classified considering annual mean wave height (Hs) as well as seasonal wave heights. This paper presents the methods used and results of the coastal classification along the central east coast of India. � 2015 Published by Elsevier Ltd.Item Classification of tidal inlets along the central east coast of India(Elsevier Ltd, 2015) Reddy, N.A.; Mendi, M.; Rao, S.; Seelam, J.K.Coastal inlets are the openings along the coastline that provide a linkage between the open ocean and the hinterland water bodies. These coastal inlets are varied in nature depending on many influencing parameters such as tide, wind, river flow and waves. Amongst these parameters, the tides are the most regular while waves and freshwater flow are more seasonal. The tidal inlets have to be examined and studied to understand the nearshore coastal processes. The inlet remains stable (i.e. open) as long as the alongshore sediment bypasses the tidal inlet. Classification of coastal systems in a broader view is necessary for the management of tidal inlets. There are several methods to classify tidal inlets based on different perspectives namely geo-morphological, hydrodynamic etc. In the present study, tidal inlet classification is carried out considering the hydrodynamics and morphodynamics along the Andhra Pradesh coast, considering the classification method as in Hayes (1984) and Thuy (2013). The Hayes (1984) classification considers only the tidal range and significant wave height, whereas Thuy (2013) considers discharge due to tide (∼Tidal prism/tide duration) and wave (∼√gH5). A total of 108 tidal inlets along Andhra Pradesh coast on the east coast of India are classified considering annual mean wave height (Hs) as well as seasonal wave heights. This paper presents the methods used and results of the coastal classification along the central east coast of India. © 2015 Published by Elsevier Ltd.Item Classification of tidal inlets along the central west coast of India(2015) Vikas, M.; Reddy, N.A.; Rao, S.; Seelam, J.K.Tidal inlets along the Maharashtra coast on the central west coast of India were classified according to three methods available in the literature. Two classification methods viz., (i) Hydrodynamic classification (Hayes, 1979) and (ii) Classification based on dimensionless parameters (Vu, 2013) used for the classification are compared with the morphological classification of de Vriend et al., (1999). The hydrodynamic classification of Tidal inlets along Maharashtra coast is carried out considering mean annual significant wave height. The classification is also extended considering significant wave heights obtained for South-West monsoon, North-East monsoon and Fair Weather seasons. It has been observed that 74% of the inlets are tide dominated as per morphological classification whereas considering annual mean wave heights in Vu (2013) method, 67% of the inlets are wave dominated. � 2015 The Authors. Published by Elsevier Ltd.