Department of Electrical Engineering

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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

Graphene was synthesized and used as a counter electrode in place of platinum in dye sensitized solar cells. This study reveals that the graphene synthesized by reduction of graphene oxide still contains functional groups even after reduction. The synthesized graphene counter electrodes were prepared by screen printing fabrication techniques. The influence of temperature variation on the films morphology, crystallinity, and its interfacial adhesiveness to the fluorine doped tin oxide coated glass were studied. Screen printing technique has shown uniform surface, decreased agglomeration of nanoparticles and high film adhesiveness. The screen printed film annealed at 400 degrees C reveals best surface morphology

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Department of Chemistry

Investigation of Chemically Synthesized Graphene as Counter Electrode for Dye Sensitized Solar Cells

1D gold gratings are optimally designed using Rigorous Couple Wave Analysis (RCWA) to realize angle dependent color shifting property. This interesting optical property is experimentally confirmed on the gratings fabricated using Dip pen nanolithography. © OSA 2014.

Proceedings 12th International Conference on Fiber Optics and Photonics, Photonics 2014

Color shifting properties of 1D gold gratings fabricated using Dip pen nanolithography

This paper presents the growth and release process effects on the deformation of suspended gold micro-structures. Cantilever type test structures, typically used for RF MEMS devices have been examined. The structures have a thickness of 2μm, produced by patterned gold electro deposition above a sacrificial photoresist layer, then removed by dry release in oxygen plasma ashing and wet release using critical point dryer (CPD). The growth process of gold electroplating is optimized for low residual stress using pulse power supply. Minimum stress 35-60 MPa is obtained at grain size 30-45nm and RMS roughness of the order of 5-8nm. The growth mechanism of structural layer and releasing methods are optimized to obtain planar MEMS structures. The main parameters considered are the initial stress during the growth of electroplated gold and the release process recipes developed for fabrication of metallic structural layer. © 2014 SPIE.

Proceedings of SPIE - The International Society for Optical Engineering

Residual stress control during the growth and release process in gold suspended microstructures

High Dynamic Range (HDR) imaging has been gaining popularity in recent years. Different from the traditional low dynamic range (LDR), HDR content tends to be visually more appealing and realistic as it can represent the dynamic range of the visual stimuli present in the real world. As a result, more scene details can be faithfully reproduced. As a direct consequence, the visual quality tends to improve. HDR can be also directly exploited for new applications such as video surveillance and other security tasks. Since more scene details are available in HDR, it can help in identifying/tracking visual information which otherwise might be difficult with typical LDR content due to factors such as lack/excess of illumination, extreme contrast in the scene, etc. On the other hand, with HDR, there might be issues related to increased privacy intrusion. To display the HDR content on the regular screen, tone-mapping operators (TMO) are used. In this paper, we present the universal method for TMO parameters tuning, in order to maintain as many details as possible, which is desirable in security applications. The method's performance is verified on several TMOs by comparing the outcomes from tone-mapping with default and optimized parameters. The results suggest that the proposed approach preserves more information which could be of advantage for security surveillance but, on the other hand, makes us consider possible increase in privacy intrusion. © 2014 Copyright SPIE.

An automated approach for tone mapping operator parameter adjustment in security applications

In this article, we identify adaptive sampling strategies for haptic signals. Our approach relies on experiments wherein we record the response of several users to haptic stimuli. We then learn different classifiers to predict the user response based on a variety of causal signal features. The classifiers that have good prediction accuracy serve as candidates to be used in adaptive sampling. We compare the resultant adaptive samplers based on their rate-distortion tradeoff using synthetic as well as natural data. For our experiments, we use a haptic device with a maximum force level of 3 N and 10 users. Each user is subjected to several piecewise constant haptic signals and is required to click a button whenever he perceives a change in the signal. For classification, we not only use classifiers based on level crossings and Weber's law but also random forests using a variety of causal signal features. The random forest typically yields the best prediction accuracy and a study of the importance of variables suggests that the level crossings and Weber's classifier features are most dominant. The classifiers based on level crossings and Weber's law have good accuracy (more than 90%) and are only marginally inferior to random forests. The level crossings classifier consistently outperforms the one based on Weber's law even though the gap is small. Given their simple parametric form, the level crossings and Weber's law-based classifiers are good candidates to be used for adaptive sampling. We study their rate-distortion performance and find that the level crossing sampler is superior. For example, for haptic signals obtained while exploring various rendered objects, for an average sampling rate of 10 samples per second, the level crossings adaptive sampler has a mean square error about 3dB less than the Weber sampler. © 2014 ACM 1544-3558/2014/12-ART16 $15.00.

ACM Transactions on Applied Perception

Design and analysis of predictive sampling of haptic signals

This paper explores the design of a non-linear output-feedback control technique based on the higher order sliding mode approach for an uncertain manual gas metal arc welding (GMAW) system. To cope with the large uncertainties affecting the dynamics of the system and the rapid changes in contact tip to workpiece distance (CT) caused by the uneven movement of the welding gun by the operator, an output-feedback control system has been developed with an observer-controller that combines the second order sliding mode (SOSM) controllers and an SOSM differentiator. A non-linear single input single output (SISO) system model has been considered here for the design. Thus, the robust output feedback controller with observer is proposed here, which has been compared with an earlier proposed classical feedback linearisation approach. Simulation results are presented and discussed in order to establish a framework for comparison. Copyright © 2014 Inderscience Enterprises Ltd.

International Journal of Modelling, Identification and Control

Output-feedback control of arc length for manual gas metal arc welding with higher order sliding modes

The Stewart platform manipulator is a 6 degrees of freedom parallel robot with a superior performance over serial robots. A variable gain super twisting algorithm ensuring global finite time convergence to the desired sliding surface is proposed for the position stabilization of the Stewart platform. For a given position of the platform, the leg lengths are estimated using inverse kinematics and corresponding leg velocities are obtained using a super twisting observer. The desired position of the platform is achieved using the proposed controller even in the presence of matched disturbances. The effectiveness of the proposed controller has been proved with the simulation results. © 2014 IFAC.

IFAC Proceedings Volumes (IFAC-PapersOnline)

Variable gain super twisting controller for the position stabilization of Stewart platform

A new type of counter electrode for dye sensitized solar cells has been fabricated using a stainless steel sheet as substrate and graphite, graphene and multiwall carbon nanotubes as the catalytic material which applied by screen printing technique. The sheet resistances of the substrates and there influence on the dye sensitized solar cells has been studied. The fabricated counter electrodes i.e. SS-graphite, SS-graphene SS-MWCNT and SS-platinum were tested for their photovoltaic response in the form of dye sensitized solar cells.

Carbon Coated Stainless Steel as Counter Electrode for Dye Sensitized Solar

Nonpolar a-plane InN films were grown on r-plane sapphire substrate by plasma assisted molecular beam epitaxy with GaN underlayer. Effect of growth temperature on structural, morphological, and optical properties has been studied. The growth of nonpolar a-plane (1 1 -2 0) orientation was confirmed by high resolution X-ray diffraction study. The film grown at 500 °C shows better crystallinity with the rocking curve FWHM 0.67° and 0.85° along [0 0 0 1] and [1 -1 0 0] directions, respectively. Scanning electron micrograph shows formation of Indium droplets at higher growth temperature. Room tem-perature absorption spectra show growth temperature dependent band gap variation from 0.74-0.81 eV, consistent with the expected Burstein-Moss effect. The rectifying behaviour of the I-V curve indicates the existence of Schottky barrier at the InN and GaN interface. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Physica Status Solidi (C) Current Topics in Solid State Physics

Effects of growth temperature on nonpolar a-plane InN grown by molecular beam epitaxy

A comparison of dry and wet release methods for surface micromachining of metallic structures, such as RF MEMS switches, test structures, bridges, and cantilevers is presented. The dry release process is optimized by varying the concentration of O2 and CF4 plasma and RF power. The plasma ashing of the sacrificial layer typically results in damage to metallic structures or stress-related deformation due to rise in temperature (80°C). A wet release process using critical point drying (CPD) has been investigated to realize gold-electroplated structures with reduced residual stress. The CPD, being a low-temperature (31.1°C) process, is more suitable for compliant structures without any deformation. © 2014 Society of Photo-Optical Instrumentation Engineers.