Department of Electrical Engineering

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IIT Jodhpur

This paper presents the development of gold-doped tin oxide (SnO2) film, realized by radiofrequency (RF) sputtering, which is highly sensitive for carbon monoxide (CO) gas. According to the Occupational Safety and Health Administration (OSHA), human exposure to 50 ppm CO is safe up to 8 h (as permissible exposure limit), but inhalation of higher concentrations of CO can cause headache, dizziness, nausea, etc. Hence, it is imperative to detect CO gas in low concentrations. The receptor films were prepared via reactive co-sputtering of high-purity Sn and Au targets and characterized by x-ray diffraction (XRD), which confirmed the presence of SnO2 and gold. The thin films of pristine SnO2 and gold-doped SnO2 were also examined through field emission scanning electron microscopy (FESEM) images, showing the distinction in their structures. A reasonably enhanced response of ~ 56.4% was exhibited by gold-doped SnO2 compared to 15.5% for pristine SnO2 for 50 ppm CO at operating temperature of each film. © 2020, The Minerals, Metals & Materials Society.

World University root node

Journal of Electronic Materials

Gold-Doped Tin Oxide Film for Highly Sensitive Carbon Monoxide Sensing

This paper presents the modeling of electrothermally actuated bimorph actuator for out-of-plane actuation application. Al-Si bimorph was optimized for higher displacement applications. Temperature distribution analysis of the Al-Si bimorph combination was chosen due to their larger displacement range. The modeling of Al-Si was performed with FEM and analytical analysis. Temperature distribution across the bimorph actuator with respect to length and applied voltage was optimized using FEM, lumped, and analytical analysis. The maximum temperature across Al-Si bimorph was achieved around 106 °C without convection and 85 °C with convection. © 2021, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Springer Proceedings in Mathematics and Statistics

Modeling of Electrothermal Microactuator

The work presents a novel computationally efficient transmission policy for throughput maximization over point-to-point sensor links employing harvest-use-store protocol with finite storage capacity battery. In these settings, under finite averaging duration constraint, the stochastic dynamic programming (SDP) technique provides the optimal solution for throughput maximization, but the implementation complexity for SDP is prohibitively large. Thus, there is a need to explore new solutions that can provide near-optimal throughput with lower implementation complexity. The work in this paper presents a adaptive transmission policy based on uniform thresholding that achieves a near-optimal throughput obtainable by SDP. Quantitative comparison with optimal online policies shows that the proposed policy attains performance close to SDP with lower implementation complexity.

Wireless Networks

Uniform thresholding based transmission policy for energy harvesting wireless sensor nodes in fading channel

We show that the output beam exiting from the end facet of a single-mode–multimode–few-mode device can be designed to be a highly pure LG00 or LG01 mode. Our investigation provides a method to generate LG beams in free space using a low-cost, all-fiber solution that also shows potential for an integrated device. © 2021 Optical Society of America

Journal of the Optical Society of America B: Optical Physics

Generation of highly pure lower-order Laguerre–Gaussian radial beams using an all-fiber multimode interference method

Logic gates are designed using symmetric lateral doping-free bipolar junction transistor (BJT) on silicon on insulator (SOI) using differential pass transistor logic, and their performance matrices are presented. Charge carriers are induced in lightly doped emitter and collector regions using two unique approaches. i.e., the charge plasma (CP) and polarity control (PC). AND, OR and XOR gates are designed using four types of devices (CP-NPN, CP-PNP, PC-NPN, and PC-PNP) and transient and noise margin analysis are performed. The transient response shows rise and fall time less than 100 ps while worst-case noise margin of 0.25 V observed for an input voltage of 1 V. Moreover, 2:1 multiplexer is also designed and explored for output transient and voltage levels. The delay of less than 2.2 ns is achieved with a nominal deviation of 0.1 V and 0.04 V for high and low output levels respectively. © 2021 Elsevier Ltd

Solid-State Electronics

Exploration of logic gates and multiplexer using doping-free bipolar junction transistor

Lowering the processing temperature is a crucial factor in the development of flexible electronic devices. Here we report the fabrication of high-performance OFETs based on room temperature deposited Ba0.5Sr0.5TiO3 (BST) as a high-k dielectric layer. The fabricated devices exhibited excellent performance while operating at a low voltage of -3 V along with demonstrating high operational stability when tested for 1 h bias stress and continuous transfer measurement cycles. In addition, inverter circuit performance is also investigated with these devices by connecting them to external loads. © 2021 IEEE.

FLEPS 2021 - IEEE International Conference on Flexible and Printable Sensors and Systems

Low Voltage Organic Field-Effect Transistors with Room Temperature Deposited Dielectric Layer

Arc welding is an indirectly controlled process where the electrical variables of arc are controlled to create joints of requisite mechanical and metallurgical characteristics after maintaining workable environment for the welder. Constant voltage arc types are mostly used in industry because they are energy efficient, more productive and welder friendly, these processes could be easily automated. However, the nature of arc types for CV processes appears drastically different for different metal transfer modes, input conditions, and process settings. The nonlinear arc itself poses as altogether different loads to power controller. Moreover, the process consists of several dynamic activities, each having different response time, their interaction with control variables add extra burden to controller. To simplify controller design, the input conditions of the process are defined in such a way that minimally defined two-input process could be controlled by controlling two independent dynamic activities. To meet that purpose with increased robustness this article proposes to use two independent easily implementable yet superior SOSM controllers—one for control of arc and another for control of wire feed speed. Robust control of wire feeding would reduce disturbance burden on the arc controller. The approach would be experimentally validated by practically designing both controllers along with creating requisite joints for wide range use suitable for ready-to-use in industrial applications. © 2021, Springer Nature Singapore Pte Ltd.

Studies in Systems, Decision and Control

Industry-Grade Robust Controller Design for Constant Voltage Arc Welding Process

A novel unknown input observer (UIO) using sliding modes is proposed for a general class of uncertain, nonlinear systems. The system generalization over-comes requirement of observability matching condition for the uncertainties and also does not rely on any transformation techniques, typically used for nonlinear systems. The UIO philosophy of disturbance decoupling is used for compensating the matched disturbances and overall robustness is engineered using sliding modes. Fault detection is proposed using the estimations. The efficacy of the method is illustrated through simulations on a quadruple tank process (QTP) plant. © 2021 IEEE.

IECON Proceedings (Industrial Electronics Conference)

Robust Unknown Input Observer for Uncertain Non-Linear Systems using Sliding Modes with Fault Detection

This brief introduces a practical sliding mode using state depended intermittent control strategy. Robust stabilization of the linear time-invariant system is achieved by rejecting the effect of matched and bounded input disturbances using the proposed state dependent intermittent sliding mode control (SDI-SMC). The system trajectories are driven to a predesigned practical sliding mode band by the proposed control to establish a practical sliding mode. The salient feature of the proposed control strategy is that the control is turned off whenever it is not necessary, which will result in a considerable saving in the control effort and other resources. The proposed SDI-SMC is simulated on the model of an industrial plant emulator and a detailed comparison is done with sliding mode control (SMC), event-triggered sliding mode control (ET-SMC) and adaptive sliding mode control (Adp-SMC). © 2004-2012 IEEE.

IEEE Transactions on Circuits and Systems II: Express Briefs

Practical Sliding Mode Using State Depended Intermittent Control

Typically, if the system is right-invertible only, then this implies that the number of inputs is more than that of outputs as well as states of the system. Over-actuated systems belong to such class. In this paper, a systematic design of a reduced-order super-twisting control is proposed to track arbitrary reference signals for uncertain non-minimum phase over-actuated systems. The proposed method involves the transformation that resolves the redundancy in the control inputs so that system can be represented as a normally-actuated system with virtual control inputs. Further, unstable zero dynamics are virtually stabilized through one more transformation so that stable and virtually stable zero dynamic states can be excluded from the super-twisting control design. Finally, the computed virtual control magnitude is spread across all the actuators via a redistributed pseud-inverse type of control allocation so that the system can be operated within the actuator saturation limits. © 2021 Elsevier Ltd