Department of Mechanical Engineering

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IIT Jodhpur

The transfer of elements C, Si, Mn, P and S from slag into the weld metal or from weld metal into the slag and microhardness has been studied using formulated fluxes. The fluxes have been formulated using extreme vertices design with an aim to develop mathematical models for change in element content and mechanical properties versus flux constituents for submerged arc welding of high-strength low-alloy steel. It is found that CaO is the most significant flux constituent and Al2O3 is the second most significant constituent among individual mixtures. CaO·MgO and CaO·Al2O3 among binary mixtures have significant effect on element transfer and microhardness. Developed mathematical models have been checked for adequacy using t-test and analysis of variance (F-test). Flux mixtures' composition has been provided for optimum chemical composition and mechanical properties. One of the optimum flux mixture with composition, CaO 11.61, Al2O3 12.33, CaF2 15.00 and MgO 39.06, would be providing desirable chemical composition and mechanical properties. © IMechE 2014.

World University root node

Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture

Prediction of element transfer due to flux and optimization of chemical composition and mechanical properties in high-strength low-alloy steel weld

This paper presents a unified approach for dynamic modeling and analysis of a biped. A biped is modeled as a floating-base system where the foot-ground interactions are modeled as external forces and moments. Dynamic modeling is proposed using the concept of the Decoupled Natural Orthogonal Complement (DeNOC) matrices. The equations of motion thus obtained are independent of topology of the biped. The advantage of the proposed modeling is highlighted in the paper. A numerical example of a 7-link biped is provided using the methodology presented. Copyright (c) 2010 by JSME.

5th Asian Conference on Multibody Dynamics 2010, ACMD 2010

A unified approach to dynamics of a biped

In oil and gas industries, submerged arc welding is the only primarily used process to weld high thickness, large distance structural oil pipes. Welding process parameters play a significant role in determining the quality of a weld joint in submerged arc welding. In the present work, an attempt has been made to optimize the weld bead parameters: weld bead form factor, dilution, microhardness and diffusible hydrogen content for welding of structural pipe steel (API 5L X65 grade) by desirability function approach used by Derringer and Harrington. For design of experiments, response surface methodology had been used. Mathematical models for output responses had been developed in terms of welding parameters and checked for adequacy using t-test and analysis of variance (F-test). It was found that welding current was the most significant parameter controlling all the responses, and arc voltage had increasing effect on all the responses except microhardness. © IMechE 2013.

Effect of welding parameters on bead profile, microhardness and H 2 content in submerged arc welding of high-strength low-alloy steel

The Indian Institute of Technology, Jodhpur (IITJ) has been monitoring and recording all the parameter of 101 kW (43.30 kW A-Si PV system located in Block 1 and 58.08 kW C-Si PV system in Block 2) grid tied solar photovoltaic system over the 4 year. The paper present the operational data 43.30 kW amorphous silicon (A-Si) based PV system located at Block 1 and 58.08 kW crystalline silicon based PV system at Block 2 of IIT Jodhpur. This paper helps in a study of the performance and consistency of this system. This paper will estimate the theoretical and actual Power output, Energy yield of the both PV systems. During the year, the PV systems in Jodhpur, India have generated a 74922 kWh by C-Si PV and 55910 kWh solar energy by A-Si PV system. As a whole, the location of Solar PV system is the primary reason of energy variability and system production. © 2014 IEEE.

Department of Mathematics

3rd International Conference on Renewable Energy Research and Applications, ICRERA 2014

A comparative performance analysis of C-Si and A-Si PV based rooftop grid tied solar photovoltaic systems in Jodhpur

This paper is devoted to the study of non-conforming h-p spectral element methods for three dimensional elliptic problems on non-smooth domains using parallel computers. To overcome the singularities which arise in the neighbourhoods of vertices, edges and vertex-edges we use local systems of coordinates together with geometric meshes which become finer near corners and edges. We provide estimates for the error and the computational complexity of our method and present results of numerical simulations that have been performed to validate the theoretical estimates obtained in [22]. © 2014 Elsevier Inc. All rights reserved.

Applied Mathematics and Computation

H-p Spectral element methods for three dimensional elliptic problems on non-smooth domains

For performance improvement and noise reduction, swept and anhedral tips have been incorporated in advanced geometry rotor blades. While there are aerodynamic benefits to these advanced tip geometries, they come at the cost of complicated structural design and weight penalties. The effect of these tip shapes on loads, vibration and aeroelastic response are also unclear. In this study, a comprehensive helicopter aeroelastic analysis which includes rotor-fuselage coupling shall be, briefly, described and the analysis results for rotor blades with straight tip, tip-sweep and tip-anhedral shall be presented and compared. The helicopter modeled is a conventional one with a hingeless single main rotor and single tail rotor. The blade undergoes flap, lag, torsion and axial deformations. Aerodynamic model includes 3-state Peters-He dynamic wake theory for inflow and the modified ONERA dynamic stall theory for airloads calculations. The complete 6-dof nonlinear equilibrium equations are solved for analyzing any general flight condition. Response to pilot control inputs is determined by integrating the full set of nonlinear equations of motion with respect to time. The effects of tip-sweep and tip-anhedral on loads and vehicle response to pilot inputs shall be presented.

40th European Rotorcraft Forum 2014

Comparative study of the influence of straight and modified-tip rotor blades on loads and control response: Session subject - Dynamics

This study proposes a robust controller in conjunction with the dynamic modeling of an existing three degrees of freedom planar parallel manipulator which can perform effectually in the presence of parameter uncertainties and external disturbances. The planar manipulator discussed here has three legs each with a prismatic-prismatic-revolute (3-PPR) joint configuration and located on the same plane connecting the moving platform which is in the form of an equilateral triangle. Each leg consists of an active prismatic joint, a passive prismatic joint and a passive rotary joint. The dynamic model has been obtained using the Euler-Lagrangian formulation method which is based on the kinetic and potential energies of the system. The proposed controller is based on a sliding mode control scheme with a nonlinear disturbance observer incorporated which aids in eliminating disturbances present in the system which is a result of both disturbances (internal and external disturbances) and parameter uncertainties which might arise due to un-modeled dynamics. Computer based numerical simulations are performed to demonstrate the effectiveness of the proposed control and results confirming the same in the presence of disturbances. © 2014 IEEE.

SCES 2014: Inspiring Engineering and Systems for Global Sustainability

Robust disturbance observer based sliding mode control of a planar parallel (3-PPR) manipulator

ZnO nanobundles were grown via a nano-templating technique over a porous silica bed using an aqueous chemical route. The growth of nanobundles initiated from ZnO nano-seeds positioned at various levels over a nanoporous matrix of self-assembled polymethylsilsesquioxane nanoparticles. Bundles of different features like nanowires, nanorods and nanotubes with a high surface roughness were grown over these templates by a day-long incubation in an aqueous solution of hexamethylene tetra-amine and zinc nitrate. We envisage these ZnO nanostructures for sensitive hydrogen detection. Photoluminescence spectra indicate the nanotubes to be most sensitive towards H2. We observe high reconditionability, moderate sensitivity and a temperature dependent charge carrier reversal phenomenon. © 2014 The Royal Society of Chemistry.

RSC Advances

Hydrogen sensing based on nanoporous silica-embedded ultra dense ZnO nanobundles

A detailed numerical investigation on stability and bifurcation analysis of a highly nonlinear electrically driven MEMS resonator has been established. A nonlinear model has been developed by using Hamilton’s principle and Galerkin’s method considering both transverse and longitudinal displacement of the resonator. The special care has been paid by incorporating higher order correction of electrostatic pressure. The pull-in results and consequences of higher order correction on the pull-in stability have been investigated. Furthermore, investigation of nonlinear phenomenon for the consequences of air-gap, electrostatic forcing parameter and effective damping on overall responses has been thoroughly studied. The possible of undesirable catastrophic failure at the unstable critical points has been critically examined. Basins of attractions that postulate a unique response in multi-region state for a specific initial condition have been depicted. The obtained responses using first-order method of multiple scales have been cross compared with the findings obtained numerically. Findings from this work can significantly be adopted to identify the locus of instability in microcantilever-based resonator when subjected to AC voltage polarization. In addition, the present outcomes provide theoretical and practical ideas for controlling the systems and optimizing their operation. © 2014, Springer Science+Business Media Dordrecht.

Nonlinear Dynamics

Stability and bifurcation analysis of an electrostatically controlled highly deformable microcantilever-based resonator

An analytical moisture diffusion model which considers the influence of external resistance to mass transfer is developed. The methodology to determine constant and variable moisture diffusion coefficients, Deff is proposed. A laboratory model of mixed-mode solar dryer is constructed to perform 16 experiments for different performance dependent variables under simulated indoor conditions. The potatoes (Solanum tuberosum) of Kufri Safed variety have been chosen as the test food product. The range of variables investigated is absorbed thermal energy (150-750 W/m2); air mass flow rate (0.009-0.022 kg/s); loading density (1.08-4.33 kg/m2) and sample thickness (5-18 mm). The efficiency results have been analysed to identify the value of each process variable leading to optimal operation of dryer. The study reveals that dryer with sample thickness of 8 mm and loading density of 4.33 kg/m2 can operate optimally for absorbed energy of 450 W/m2 and air mass flow rate of 0.017 kg/s. © 2013 © 2013 Taylor &amp; Francis.