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Dhake P.D.,SVNIT Surat | Patil H.S.,SVNIT Surat | Patil Y.D.,SVNIT Surat
Proceedings of the Institution of Civil Engineers: Structures and Buildings | Year: 2015

Four exterior reinforced concrete beam–column joint specimens with varying amounts of joint hoop reinforcement are constructed and tested under reverse cyclic loading to assess their performance during earthquakes. Headed bars are used in all the specimens. Various parameters such as crack pattern, hysteresis behaviour, modes of failure, energy dissipation, displacement ductility, stiffness degradation and maximum shear strength are studied. The effectiveness of headed bars with short embedded length terminating in the exterior beam–column joint is assessed. As headed bars have the advantage of transferring a more uniform distribution of compressive stress to the concrete at the headed end, they enable the development of a wider compressive strut in the joint, which enhances the joint shear strength under seismic loading. This makes it possible to reduce transverse reinforcement in joints when using headed bars as longitudinal beam reinforcement. © Thomas Telford Services Ltd. All rights reserved 2015.

Patel P.A.,SVNIT Surat | Desai A.K.,SVNIT Surat | Desai J.A.,SVNIT Surat
Magazine of Concrete Research | Year: 2013

The integrity of a reinforced concrete structure should be safe and stable under lateral loads, especially those structures that depend on the behaviour of the beam-column joint. The ductility capacity of structural elements has a key role to play in seismic design. The ability of the structure to sustain levels of inelastic deformation under lateral loads, implicit in ductility values, is dependent on the material and detailing used. For the ductile behaviour of beam-column joints, a considerable amount of lateral reinforcement is necessary. An experimental investigation is presented on the use of steel fibre reinforced concrete (SFRC) to provide ductility in a beam-column joint even after the increase in hoop spacing of lateral ties. Six one-third scale exterior beam-column joints were tested under reverse cyclic loading. The SFRC beam-column joint contained volume fraction of 1.5% steel fibre for all variable hoop spacing. The results were compared and evaluated with respect to strength, displacement ductility, energy dissipation, specific damping capacity and stiffness. Experimental results reveal that a SFRC beam-column joint performs satisfactorily and improved joint behaviour is indicated. The results also indicate that a reduction in the number of lateral ties in the beam-column joint by the appropriate use of SFRC can be an alternative solution for avoiding conjunction of reinforcement.

Shegokar N.L.,SVNIT Surat | Lal A.,SVNIT Surat
Advanced Materials Research | Year: 2013

This paper deals with the stochastic nonlinear free vibration response of functionally graded materials (FGMs) beam subjected to thermal loadings with uncertain material properties subjected to uniform and nonuniform temperature changes with temperature independent (TID) and dependent (TD) material properties. System properties such as material properties of each constituent's material and volume fraction index are taken as independent random input variables. The basic formulation is based on higher order shear deformation theory (HSDT) with von-Karman nonlinear strains using modified C0 continuity. A direct iterative based nonlinear finite element method in conjunction with first order perturbation technique (FOPT) is used for FGMs beam to compute the second order statistics (mean and coefficient of variation) of the nonlinear fundamental frequency. The present outlined approach has been validated with the results available in literatures and independent Monte Carlo simulation (MCS). © (2013) Trans Tech Publications, Switzerland.

Saladi S.,SVNIT Surat | Menghani J.,SVNIT Surat | Prakash S.,Indian Institute of Technology Roorkee
Journal of Materials Engineering and Performance | Year: 2014

Cyclic oxidation behavior of detonation-gun-sprayed Ni-5Al coating on Inconel-718 is discussed in the present study. Oxidation studies were carried out on both bare and coated superalloy substrates in air at 900 °C for 100 cycles. The thermogravimetric technique was used to establish kinetics of oxidation. X-ray diffraction, FESEM/EDAX, and x-ray mapping techniques were used to analyze the oxidation products of bare and coated samples. The weight gain of bare superalloy was higher than the Ni-5Al-coated superalloy. Both bare and Ni-5Al-coated superalloys followed nearly parabolic oxidation behavior. The Ni-5Al coating was able to reduce the overall weight gain by 26.2% in comparison with bare superalloy in the given environment. The better oxidation resistance of Ni-5Al coating may be due the formation of protective oxides phases such as NiO, Al2O3, and NiAl2O4 on the oxidized coating and Cr2O3 at the coating-substrate interface. The Ni-5Al coatings obtained from detonation-gun-spraying process showed very little porosity and low surface roughness values. © 2014, ASM International.

Malpani A.,SVNIT Surat
IFIP International Conference on Wireless and Optical Communications Networks, WOCN | Year: 2012

The performance of ground to satellite Free Space Optical (FSO) communication link is degraded due to the presence of atmospheric turbulence that causes fluctuations in both intensity and phase of the received optical signal. In this paper, bit error rate (BER) performance of FSO link using low-overhead technique i.e., aperture averaging is investigated for coherent (sub-carrier BPSK) and non-coherent (OOK) modulation schemes in weak atmospheric turbulence channel. RSoft OptSim software is used to design communication links for these modulations and simulation is done in the block mode. It is seen that aperture averaging along with coding schemes provides robust mitigation strategies. It is observed that sub-carrier BPSK modulation outperforms the other modulation scheme i.e., OOK in terms of less probability of error rate if all other parameters are kept constant or varied accordingly. Also, sensitivity of modulation schemes towards different channel parameters is observed for aperture averaging. © 2012 IEEE.

Baloni B.D.,S.V.N.I.T. Surat | Pathak Y.,S.V.N.I.T. Surat | Channiwala S.A.,S.V.N.I.T. Surat
Computers and Fluids | Year: 2015

The performance of centrifugal blower is enhanced with an optimization process on the blower volute using Taguchi method and ANOVA approach. The important geometrical parameters of volute are prioritized by applying first level of analytic hierarchy process. The analytic hierarchy process (AHP) is a structured technique for organizing and analyzing complex decisions, based on mathematics and psychology. Based on review of literatures, three levels are defined for each geometrical parameter. Reduction in the percentage variation of static pressure at impeller outlet, minimization of losses inside volute and maximization of stagnation pressure at volute outlet are selected as quality characteristics to ensure the enhancement of centrifugal blower performance. In this process, numerical simulation of 3-D flow in single stage centrifugal blower volute is carried out by FLUENT software for matrix experiments. These matrix experiments are suggested by Minitab software. The simulation case is carried out by flow, turbulence and Energy equations using SIMPLE pressure-velocity coupling. Standard discretisation method is used to solve pressure whereas; others are solved by second order upwind discretisation method. The realizable k-. ε is adapted as turbulence model. Stator-rotor interactions are defined by means of mixing plane model of multiple rotating reference frames. Impeller is situated in rotating reference frame whereas; volute is in fixed reference frame. The process reveals that optimization of the original geometry of blower, at 1.5 times width of impeller, 24° tongue angle and 10% reduction in volute outer radial locations, pressure head and flow uniformity increases compared to other cases; this improvement takes place due to reduction in the non-uniformity of flow at impeller outlet and losses inside the volute passages. The experimental performance of optimized configuration is carried out and compared with existing centrifugal blower. The result indicates better performance in case of optimized volute than original configuration of volute. In case of optimized centrifugal blower, 7.4% higher efficiency is observed at the design rated speed compared to existing centrifugal blower. © 2015 Elsevier Ltd.

Rathod M.K.,SVNIT Surat | Banerjee J.,SVNIT Surat
Experimental Heat Transfer | Year: 2014

Thermal performance of a latent heat storage unit is evaluated experimentally. The latent heat thermal energy storage system analyzed in this work is a shell-and-tube type of heat exchanger using paraffin wax (melting point between 58°C and 60°C) as the phase change material. The temperature distribution in the phase change material is measured with time. The influence of mass flow rate and inlet temperature of the heat transfer fluid on heat fraction is examined for both the melting and solidification processes. The mass flow rate of heat transfer fluid (water) is varied in the range of 0.0167 kg/s to 0.0833 kg/s (1 kg/min to 5 kg/min), and the fluid inlet temperature is varied between 75°C and 85°C. The experimental results indicate that the total melting time of the phase change material increases as the mass flow rate and inlet temperature of heat transfer fluid decrease. The fluid inlet temperature influences the heat fraction considerably as compared to the mass flow rate of heat transfer fluid during the melting process of the phase change material. © Taylor and Francis Group, LLC.

Reddy P.G.,SVNIT Surat | Kundu P.,SVNIT Surat
2014 Annual International Conference on Emerging Research Areas: Magnetics, Machines and Drives, AICERA/iCMMD 2014 - Proceedings | Year: 2014

Partial Discharge (PD) measurement is a precise diagnosis to give the knowledge about the condition of the insulation. There are several methods to detect and measure the PD such as Electrical, Acoustic, Optical, Chemical and Ultra High Frequency (UHF) detection methods. Among all these methods, UHF sensor plays crucial role to detect the PD, efficiently with high sensitivity. PD pulses tend to appear only in the time of nano-seconds, which pulses can be detected without any power outage by using high bandwidth antenna i.e. UHF sensor. UHF sensor is conical in shape with base diameter 2.5cm and axial length 10cm. This sensor can detect the electromagnetic interference signals without any background noise in the range of 300 MHz to 1.5 GHz. In this paper, the experimental work was presented to study the characteristics of PD by using the designed UHF conical monopole antenna with the help of high bandwidth digital oscilloscope connected through co-axial cables in two distinct lengths. FFT analysis was applied to deduce the frequency response of the PD signal and sensitivity of the antenna. © 2014 IEEE.

Jagtap K.R.,SVNIT Surat | Lal A.,SVNIT Surat | Singh B.N.,Indian Institute of Technology Kharagpur
International Journal of Mechanics and Materials in Design | Year: 2012

This study deals with the stochastic nonlinear bending response of functionally graded materials (FGMs) plate with uncertain system properties subjected to transverse uniformly distributed load in thermal environments. The system properties such as material properties of each constituent's material, volume fraction index and transverse load are taken as independent random input variables. The material properties are assumed to be temperature independent (TID) and temperature dependent (TD). The basic formulation is based on higher order shear deformation theory with von-Karman nonlinear strain kinematics using modified C 0 continuity. A direct iterative based nonlinear finite element method in conjunction with first-order perturbation technique developed by last two authors for the composite plate is extended for the FGM plate to compute the second order statistics (mean and standard deviation) of the nonlinear bending response of the FGM plates. Effects of TD, TID material properties, aspect ratios, volume fraction index and boundary conditions, uniform temperature and non-uniform temperature distribution on the nonlinear bending are presented in detail through parametric studies. The present outlined approach has been validated with the results available in the literature and independent Monte Carlo simulation. © 2011 Springer Science+Business Media, LLC.

Sharma P.J.,SVNIT Surat | Patel P.L.,SVNIT Surat | Jothiprakash V.,Indian Institute of Technology Bombay
ISH Journal of Hydraulic Engineering | Year: 2016

The monthly time step stochastic dynamic programming (SDP) model has been applied to derive the optimal operating policies of Ukai reservoir, a multipurpose reservoir in Tapi river basin, India. The initial reservoir storages and inflows into the reservoir in a particular month are considered as hydrological state variables. Since flood control and irrigation are the two major purposes of this reservoir, the SDP model is developed with the objective of minimizing annual sum of squared deviations of actual releases and actual storages from their respective target values. The uncertainty in the prediction of inflows into the reservoir system is addressed by incorporating the inflow transition probabilities. In this study, the effect of state variable discretization in deriving optimal operating policies using SDP for the reservoir is investigated. From the model results, it is inferred that, by adopting unequal interval storage discretization approach over equal interval storage discretization approach, there is an improvement of about 8–58% in the values of the objective function. The optimal operating policies derived using unequal interval storage discretization have been expressed in terms of final storages (levels) for each month for various combinations of inflows and initial storages. © 2016 Indian Society for Hydraulics

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