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Variation of Flow Field Around Twin Cylinders with and Without the Outer Perforated Cylinder ? Numerical Study

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China Ocean Engineering 2016年第5期30卷 763-771页

作者： chandrasekaran srinivasan N.MADHAVI Department of Ocean Engineering Indian Institute of Technology Madras Department of Ocean Engineering IIT Madras

Presence of the outer perforated cylinder reduces the direct wave impact on the inner cylinder, which has been testified by many researchers. However, the force reduction mechanism, which is complicated due to the wave-porous structure interaction, needs to be addressed in detail. The present study explains the mechanism with the aid of the computational fluid dynamics （CFD） tool STAR CCM＋. This package is chosen for its capabilities to simulate viscous and turbulence effects caused by passage of waves. For the present study, flow fields around the twin cylinders with different orientations are examined with and without the outer perforated cover. Mechanism contributing to the reduction of force on the existing structure is explained in physical terms, and force reduction is quantified. The present study has direct application in the retrofitting application of offshore members.

关键词： CFD offshore structure perforated cylinder hydrodynamic force water particle kinematics twin cylinders

Laboratory experiment on using non-floating body to generate electrical energy from water waves

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Frontiers in Energy 2012年第4期6卷 361-365页

作者： Arunachalam AMARKARTHIK srinivasan chandrasekaran Karuppan SIVAKUMAR HarenderSINHMAR Bannari Amman Institute of Technology Erode 638401India Indian Institute of Technology Madras Chennai 600036India

This paper describes an innovative method of using a nonbuoyant body to harness ocean waves. All the point absorbers are buoyant in nature and move up due to buoyancy and come down because of gravity. The point absorbers are designed to move along the waves to make the device efficient. These devices face excessive stress during the rough weather on account of the extreme motion of waves and cause the total device failure. The present study shows that using a nonbuoyant body for conven tional point absorber principle is much efficient and safer than any other device proposed till today. A small scale wave energy converter with nonbuoyant body was designed, fabricated and tested in small scale wave maker. An electrical generator was coupled with the device to generate electrical energy from harnessed waves. The generator was electrically loaded and the generated power was measured. It was found from the experiments that the proposed device showed a significant improve ment in electricity generation and safety during extreme conditions. In addition to the electricity generation, the characteristics of the device were also studied by using various wave and device parameters.

关键词： ocean wave energy point absorbers heavingbody non-floating object heave response ratio electricalenergy generation

Experimental investigation and ANN modeling on improved performance of an innovative method of using heave response of a non-floating object for ocean wave energy conversion

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Frontiers in Energy 2013年第3期7卷 279-287页

作者： srinivasan chandrasekaran Arunachalam AMARKARTHIK Karuppan SIVAKUMAR Dhanasekaran SELVAMUTHUKUMARAN Shaji SIDNEY Department of Ocean Engineering Indian Institute of TechnologyMadras Chennai 600036 India Department of Mechanical Engineering Bannari Amman Institute ofTechnology TamilNadu 638401 India

To convert wave energy into usable forms of energy by utilizing heaving body, heaving bodies （buoys） which are buoyant in nature and float on the water surface are usually used. The wave exerts excess buoyancy force on the buoy, lifting it during the approach of wave crest while the gravity pulls it down during the wave trough. A hydraulic, direct or mechanical power takeoff is used to convert this up and down motion of the buoy to produce usable forms of energy. Though using a floating buoy for harnessing wave energy is conventional, this device faces many challenges in improving the overall conversion efficiency and survivability in extreme conditions. Up to the present, no studies have been done to harness ocean waves using a non-floating object and to find out the merits and demerits of the system. In the present paper, an innovative heaving body type of wave energy converter with a non-floating object was proposed to harness waves. It was also shown that the conversion efficiency and safety of the proposed device were significantly higher than any other device proposed with floating buoy. To demonstrate the improvements, experiments were conducted with non- floating body for different dimensions and the heave response was noted. Power generation was not considered in the experiment to observe the worst case response of the heaving body. The device was modeled in artificial neural network （ANN）, the heave response for various parameters were predicted, and compared with the experimental results. It was found that the ANN model could predict the heave response with an accuracy of 99%.

关键词： ocean wave energy point absorbers heaving body non-floating object heave response ratio artificial neural network (ANN)

Structural Health Monitoring of Offshore Buoyant Leg Storage and Regasification Platform:Experimental Investigations

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Journal of Marine Science and Application 2018年第1期17卷 87-100页

作者： srinivasan chandrasekaran Thailammai Chithambaram Department of Ocean Engineering IIT MadrasChennaiTamil Nadu 600036India

Offshore platforms are of high strategic importance,whose preventive maintenance is on top *** Leg Storage and Regasification Platforms(BLSRP)are special of its kind as they handle LNG storage and processing,which are highly *** of structural health monitoring(SHM)to offshore platforms ensures safe operability and structural *** damages on the offshore platforms under rare events can be readily identified by deploying dense array of sensors.A novel scheme of deploying wireless sensor network is experimentally investigated on an offshore BLSRP,including postulated failure modes that arise from tether *** of the scaled model under wave loads is acquired by both wired and wireless sensors to validate the proposed *** wireless sensor network is used to trigger alert monitoring to communicate the unwarranted response of the deck and buoyant legs under the postulated failure *** triggers the alert mechanisms on exceedance of the measured data with that of the preset threshold values;alert mechanisms used in the present study include email alert and message pop-up to the validated user *** study is a prima facie of SHM application to offshore platforms,successfully demonstrated in lab scale.

关键词： Wireless sensor network Structural health monitoring Condition-based monitoring Response analysis Alert Monitoring System Underwater sensors Postulated failure

Damage Detection in Reinforced Concrete Berthing Jetty Using a Plasticity Model Approach

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Journal of Marine Science and Application 2019年第4期18卷 482-491页

作者： srinivasan chandrasekaran P.T.Ajesh Kumar Department of Ocean Engineering Indian Institute of Technology Madras

A conventional method of damage modeling by a reduction in stiffness is insufficient to model the complex non-linear damage characteristics of concrete material *** this research,the concrete damage plasticity constitutive model is used to develop the numerical model of a deck beam on a berthing jetty in the Abaqus finite element *** model constitutes a solid section of 3D hexahedral brick elements for concrete material embedded with 2D quadrilateral surface elements as *** model was validated against experimental results of a beam of comparable dimensions in a cited *** validated beam model is then used in a three-point load test configuration to demonstrate its applicability for preliminary numerical evaluation of damage detection strategy in marine concrete structural health *** natural frequency was identified to detect the presence of damage and mode shape curvature was found sensitive to the location of damage.

关键词： Structural health monitoring Damage detection natural frequency Mode shape Curvature Damage parameters Concrete damaged plasticity model Finite element method Numericalmodel

Marine Structures under Special Loads

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Sustainable Marine Structures 2022年第2期4卷 55-56页

作者： chandrasekaran srinivasan Madras Institute of Technology India

Environmental loads that act on marine structures are highly non-deterministic in *** these loads is a basic requirement for their structural design,but their response is far beyond just counteracting the loads[1,2].The marine environment poses more challenges starting from the choice of material,structural form,design methods,construction techniques,inspection methods,repair,and retrofitting.

关键词： Marine starting structural

Comparative Study on Decision Tree Techniques for Mobile Call Detail Record

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通讯和计算机（中英文版） 2012年第12期9卷 1331-1335页

作者： Suban Ravichandran Vijay Bhanu srinivasan chandrasekaran Ramasamy Department of Computer Science & Engineering Annamalai University Annamalai Nagar 608002 India

Every mobile operator of today"s world switches their technology over from 2G (second generation) to 3G (third generation) network. Operators are keen analyzing their CDR (call detail record) obtained over the past usage for predicting the behavior of their customers and their usage. The operators are willing to mine knowledge from real-world dataset which implies the pattern of user mentality on this changing world. To identify the usage of 2G and 3G services the classification models were trained using the data collected from PAKDD 2006 dataset. In order to obtain the prediction accuracy, the classifiers were evaluated using 10 folds cross validation. On comparing the results of the experiment, J48 performed more accurately and random tree consumed less time.

关键词：移动运营商呼叫详细记录技术决策树现实世界预测精度分类模型交叉验证

Thermophoresis and Brownian motion effects on boundary layer flow of nanofluid in presence of thermal stratification due to solar energy

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Applied Mathematics and Mechanics(English Edition) 2012年第6期33卷 765-780页

作者： N.ANBUCHEZHIAN K.srinivasan K.chandrasekaran R.KANDASAMY Department of Mechanical Engineering Sri Guru Institute of Technology Department of Mechanical Engineering Anna University Department of Mechanical Engineering R.M.K.Engineering College Research Centre for Computational Mathematics Faculty of ScienceTechnology and Human DevelopmentUniversiti Tun Hussein Onn Malaysia

The problem of laminar fluid flow, which results from the stretching of a vertical surface with variable stream conditions in a nanofluid due to solar energy, is in- vestigated numerically. The model used for the nanofluid incorporates the effects of the Brownian motion and thermophoresis in the presence of thermal stratification. The sym- metry groups admitted by the corresponding boundary value problem are obtained by using a special form of Lie group transformations, namely, the scaling group of transfor- mations. An exact solution is obtained for the translation symmetrys, and the numerical solutions are obtained for the scaling symmetry. This solution depends on the Lewis number, the Brownian motion parameter, the thermal stratification parameter, and the thermophoretic parameter. The conclusion is drawn that the flow field, the temperature, and the nanoparticle volume fraction profiles are significantly influenced by these param- eters. Nanofluids have been shown to increase the thermal conductivity and convective heat transfer performance of base liquids. Nanoparticles in the base fluids also offer the potential in improving the radiative properties of the liquids, leading to an increase in the efficiency of direct absorption solar collectors.

关键词： solar radiation Brownian motion nanofluid thermophoresis thermalstratification

MIMO Multi Carrier Interleave Division Multiple Access System with Multiuser Detection: Performance Results

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International Journal of Communications, Network and System Sciences 2010年第4期3卷 413-417页

作者： Prabagarane Nagaradjane Sai N. chandrasekaran Kuttathatti srinivasan Vishvaksenan 不详

This paper provides the performance analysis of multi input multi output (MIMO) Multi carrier (MC) interleaver based multiple-access system with multiuser detection. Interleave-division multiple access (IDMA) is a scheme in which users are separated by employing different interleavers instead of different signatures as in a conventional code-division multiple-access (CDMA) scheme. The basic principle of IDMA is that the interleaver is different for different users. Interleavers are generated independently and randomly. At the receiver, ZF, LLSE, VBLAST/ZF/MAP and VBLAST/LLSE/MAP detectors are employed. The performance of the system is analyzed for different channel conditions using extensive simulation runs based on Monte Carlo simulation trials. Simulation results divulge that VBLAST/LLSE/MAP detector results in significant performance amelioration compared to other detectors as applied to MC/IDMA system.

关键词： CDMA Channel Capacity Iterative Decoding Multi-User Detection