Department of Mechanical Engineering

&ldquo;IIT Jodhpur is committed to impart quality education to facilitate the creation of qualified, competent and responsible human resources to meet the emerging technological challenges of the world. It is working towards creating an equitable learning platform that is positive, accessible and effective in the face of the modern societal and scientific advancements.

Flexibility in curriculum, in all its academic programs, encompassing elements of teaching, research, creativity, innovation and entrepreneurship is the most unique feature of IIT Jodhpur. The Department of Science and Technology (DST), under the National Mission on Cyber Physical Systems, has identified IIT Jodhpur as a Technology &amp; Innovation Hub in the area of Augmented Reality and Virtual Reality. The institute has also been nominated as the coordinator for the Jodhpur City and Knowledge Cluster by the Office of Principal Scientific Adviser, Government of India.

The sprawling 852-acre IIT Jodhpur campus is a majestic tribute to the deep-rooted diverse cultural heritage of the region. The campus is an architectural masterpiece, which is slated to become an international exemplar of sustainability with net-zero energy, and advanced water and waste management strategies.&rdquo;

IIT Jodhpur

The primary aim of this paper is to analyze solar power variability. Ground-based measurements of solar photovoltaic power are used for the forecasting of 43-kW A-Si SPV system. In this study, we describe the variability in the power production of solar photovoltaic plant at IIT, Jodhpur. Solar PV generation forecasting is playing a key role in accurate solar power dispatchability as well as scheduling of PV power for hybrid power generation systems. The actual power produced by a PV power system varies according to variation in meteorological parameters and efficiency of PV system components. For the purpose of forecasting as per the schedule in the Indian power sector, a time slot of 15 min is considered for each forecasting. The proposed generalized neural network technique will be appropriated for modeling of solar power variability forecasting. In this paper, we used generalized neural network for forecasting the PV power variability. © Springer India 2015.

World University root node

Department of Mathematics

Lecture Notes in Electrical Engineering

Ground-based measurement for solar power variability forecasting modeling using generalized neural network

Zirconium carbide-nitride absorber (ZrC-ZrN) and zirconium reflector tandem structures were prepared on glass and aluminum substrate, in conjunction with zirconium oxide (ZrOx) anti-reflection coatings, using DC/RF magnetron sputtering system. The solar absorption properties of zirconium carbide-nitride absorber layers were optimized by controlling nitrogen flow during synthesis process for optimal solar thermal response. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements were carried out on fabricated absorber-reflector tandem structures to understand the structure-property correlation. We absorbed strong dependence of zirconium nitride fraction on solar thermal performance. We observed enhanced solar absorptance α ∼ 0.86 and thermal emittance ϵ ∼ 0.05 at room temperature for structures fabricated with optimized synthesis parameters. The optimized structures are stable up to 150 °C in the air without any significant degradation in their solar performance. © 2016. The Authors.

Department of Physics

ISES Solar World Congress 2015, Conference Proceedings

Zirconium carbide-nitride composite matrix based solar absorber structures on glass and aluminum substrates for solar thermal applications

In this study a reliable shape optimization for laminated plate structures has been attempted. For a fixed higher order plate model, a simple a-posteriori strain recovery algorithm, following ZZ type patch recovery technique, has been developed. The recovery is seen to be accurate. The effect of higher approximation order and mesh refinement on the quality of the obtained solution quantities like stress components and displacements, is studied in detail. The shape of the cutout is optimized with weight minimization as the objective function and the first-ply failure criterion as the constraint. It is observed that control of the discretization error (via adaptive mesh refinements) leads to vastly different final designs, as compared to those obtained using reasonably refined meshes, but without adaptivity. It is seen that without adaptivity, the design obtained is unsafe, as either more material removal is predicted or failure is predicted at higher loads, as compared to that obtained using adaptivity. © 2015 Elsevier Ltd. All rights reserved.

Computers and Structures

Adaptive finite element based shape optimization in laminated composite plates

An aerodynamic formulation has been developed to estimate the aerodynamic loads on a blade in a cascade of slightly cambered airfoils based on Whitehead?s aerodynamic theory for cascade of flat plates. The stability of the blade is determined by solving the structural model by posing it as a complex eigenvalue problem. It is shown that the flutter velocities in the bending mode get reduced by significant margin upon the inclusion of the camber. A possible explanation is that, as the blade camber increases, the lift force experienced by the blade in the heaving direction increases due to increased loading. This makes the blade more prone to bending flutter. Also, from the flutter boundaries for cambered blades, for values of the frequency ratio moved from unity, the flutter velocity increases in the torsional mode. This means that when a cambered blade with a significant difference in bending and torsional stiffness is employed for operation torsional flutter occurs only at higher air velocities, and at lower air velocities, the structure is prone to bending flutter. At frequency ratios near unity, the flutter velocities in the bending mode and torsional mode overlap, resulting in coupled bending?torsion flutter of the blade.

AIAA Journal

Aerodynamic formulation for stability analysis of lightly cambered airfoils in cascade

Abstract Capillary tubes are extensively used in several cooling applications like refrigeration, electronic cooling etc. Local pressure variation in adiabatic straight capillary tube (mini channel) is studied experimentally and numerically with R134a as the working fluid. Experiments are performed on two straight capillary tubes. It is found that the diameter is the most sensitive design parameter of the capillary tube. Experiments are performed on five helically coiled capillary tubes to quantify the effect of pitch and curvature of helically coiled capillary tube on the pressure drop. Non dimensionalized factor to account coiling of capillary tube is derived to calculate mass flow rate in helically coiled capillary tubes. Flow visualization in adiabatic capillary tube confirms the bubbly nature of two phase flow. Numerical and experimental investigations in diabatic capillary tube suggest that the use of positive displacement pump and choking at the exit of the channel ensures flow stability. © 2015 Elsevier Ltd.

Applied Thermal Engineering

Experimental and numerical studies of choked flow through adiabatic and diabatic capillary tubes

This work focuses on enhancing step descending ability of the modular robot proposed in [16]. The proposed robot consists of three modules connected with each other through passive joints. It is propelled using an active pair of wheels per module. Since there are no actuators at the joints, the joints are not susceptible to losing operability while traversing on rugged terrain. However with the absence of actuators, we face the issue of the robot toppling over when an abnormally large obstacle is encountered. This shortcoming is overcome with the use of compliant joints. The compliant joints are designed by employing springs of optimal stiffness, which is calculated through an optimization formulation aided with the constraints presented by the static analysis of the robot. The novelty lies in the systematic design of compliant joint for step descent. The robot is successful in climbing and descending obstacles of dimension 17 cm. Simulations of the mathematically modelled robot are carried out. The results from the same are validated on a working prototype and presented. © 2015 ACM.

ACM International Conference Proceeding Series

An improved compliant joint design of a modular robot for descending big obstacles

This paper presents a novel approach for algorithmic singularity avoidance for reactionless visual servoing of a satellite mounted space robot. Task priority approach is used to perform visual servoing while reactionless manipulation of the space robot. Algorithmic singularity is prominent in such cases of prioritizing two tasks. The algorithmic singularity is different from the kinematic and dynamic singularities as the former is an artefact of the tasks at hand, and difficult to predict. In this paper, we present a geometric interpretation of its occurrence, and propose a method to avoid it. The method involves path planning in image space, and generates a sequence of images that guides the robot towards goal avoiding algorithmic singularity. The method is illustrated through numerical studies on a 6-DOF planar dual-arm robot mounted on a service satellite. © 2015 IEEE.

Proceedings of the 17th International Conference on Advanced Robotics, ICAR 2015

Switching method to avoid algorithmic singularity in vision-based control of a space robot

In this paper, we report a pneumatically actuated solenoid micro-valve with simulation, design and characterization. In micro-fluidic applications dealing with soft biological fluids very often, digital micro-valves [also known as Quake valves (Unger et al. in Science 288:113, 2000)] are deployed to start/stop flows in pressurized micro-channels. These valves are designed in a manner so that the actuation is performed by a control micro-channel filled with compressed air seating on the top of another micro-channel filled with fluidic sample. The response time of these valves is so miniscule that they almost close immediately qualifying them to be digital in nature. Still in applications like drug screening where a small amount of intermixing may have a counterintuitive effect on the whole experiment, the valves may underperform. In order to address the problem of leakages/leaching of fluids across a fully pressure-closed digital micro-valve, we have tried to incorporate a design modification with a completely different fabrication process, wherein the closing approach of a Quake valve has been varied from top down to radially inwards across the whole cross-section of the micro-channel. The design of this valve enables its wide applicability to embedded micro-fluidics, which is widely used to mimic/study the flow of body fluids across our vasculature or is highly useful for chip cooling applications. Micro-valving has been seldom explored in the embedded domain, and the current architecture of the micro-valve in a way fills this technology gap. In our design, two concentric hollow tracks, one straight and another helical are replicated in polydimethyl siloxane using preformed 80-micron copper wires that are of circular cross-section. Compressed oxygen is passed through the helical channel to control the fluid flow in the concentrically placed straight micro-channel. The micro-valve controls the fluid flow by applying uniform pressure homogeneously on micro-channel wall so that the wall can collapse and close the channel cross-section (stop condition). The system has been designed and simulated using COMSOL multi-physics platform where a design optimization was carried out in details in an earlier work (Singh et al. in Microsyst Technol. doi:10.1007/s00542-013-1738-7, 2013). In this work, we have evaluated the design experimentally through monitoring the inlet/outlet flow rate in the central micro-channel through microparticle image velocimetry (micro-PIV) analysis on opened/closed valve conditions. A flow behavior of the central micro-channel is simulated using COMSOL multi-physics platform, and the pre/post-valving discharge have been estimated theoretically for various input flow rate conditions at a corresponding air pressure of 5 psi in the helical track. We have further validated this through micro-PIV experiments wherein the valving behavior observed is different to the extent of the transient flow part but quite similar as regards the steady-state part. © 2015, Springer-Verlag Berlin Heidelberg.

Microfluidics and Nanofluidics

A novel helical micro-valve for embedded micro-fluidic applications

Background: Hydroxyapatite (HAP) has been a principal mineral phase in bone cell and tooth because of several favourable properties like anti-carcinogenicity, good mechanical strength, biocompatibility etc. ZnO being an inorganic material possesses unique properties such as antisepticity, low thermal expansion coefficient, low thermal conductivity and antimicrobial properties, all of which find prominent applications in dental materials. In this regard, we have prepared a novel biomaterial blending ZnO and HAP into a nano-composite which can be incorporated directly into the restorative glass ionomer cement (GIC) to enhance its mechanical and antibacterial properties. Results: We have fabricated the ZnO-HAP nano composite using a wet chemical route through ultrasonication process. Characterization of this nano composite has been carried out with Dynamic Light Scattering (DLS), Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infra Red Spectroscopy (FTIR) and Micro-hardness testing etc. Further, the antimicrobial properties of ZnO-HAP nano composites embedded in GIC has been investigated for the E. Coli DH5α and Streptococcus mutans and we have found out the composite to significantly retard microbial activity. Copyright © 2015 American Scientific Publishers.

Journal of Bionanoscience

Investigation of ZnO-hydroxyapatite nanocomposite incorporated in restorative glass ionomer cement to enhance its mechanical and antimicrobial properties

We measure evaporation rates from water kept in an insulated tank and which is at a temperature higher than the ambient. Different schemes are used to obtain different temperature profiles in the water layer: a) water is heated from bellow, b) water left to cool after being heated, c) water heated from above with an IR heater, d) water heated from above in a very shallow tank. The idea of having these different schemes is to check the role of water side convection on evaporation rates. In cases a) and b) unstable stratification causes convection; in case c) we have stable stratification, and in case d), the temperature is uniform in the water layer. The heating-from-above experiments simulate some aspects of evaporation from natural bodies, like lakes, due to solar radiation. Evaporation rates were measured using a precision balance. Temperatures were measured in the water and in the ambient, and a thermal camera was used to monitor the water surface temperature and visualize the convection patterns. We present results of evaporation rates under the different conditions. © 2015 Published by Elsevier B.V.