Department of Electrical Engineering

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IIT Jodhpur

This article presents a new event-triggering based design of sliding mode control (SMC) for the control of a dynamical system against external perturbations. This triggering mechanism aims to generate a sparser sampling pattern than the existing one while achieving the minimum resource utilization. The triggering mechanism employs scalar dynamics, hence it is called the dynamic event-triggering mechanism, which acts as a filter for the triggering condition. The output of this dynamics is used in the event condition in addition to a constant threshold while the part of the event function is fed as an input to this filter. The existing design algorithms for event-triggered SMC may not guarantee an increase in the inter event time for the dynamic event-triggering strategy. An alternative approach to this is proposed for the design of dynamic triggering based SMC where we partially relax the dependency of SMC gain on the event parameter without affecting the steady-state performance for the closed-loop system. It is shown that the proposed design achieves a larger inter event time leading to a sparser triggering sequence. We guarantee the stability by showing the convergence of state trajectories of the closed-loop system within any desired bound around the origin for the proposed triggering mechanism, and also the absence of the Zeno phenomenon in the triggering sequence is established. Finally, an illustration of the proposed scheme is presented in a simulation study for a mass-spring-damper system. © 2021 John Wiley & Sons Ltd.

World University root node

International Journal of Robust and Nonlinear Control

Dynamic event-triggering based design of sliding mode control

Heavy metal ions are highly toxic, carcinogens, and non-biodegradable in nature and pollute most water resources that lead to severe health-related issues. It is essential to develop highly sensitive, selective, rapid, and accurate approaches for their detection in water. Semiconducting devices and materials with micro and nanostructures have been featured with fast response time, low power, high sensitivity, low detection limit. This review concisely introduces the recent trends in heavy metal ion sensing with semiconductor devices, including ion-sensitive field-effect transistors (ISFETs) and AlGaN/GaN high electron mobility transistors (HEMTs) and semiconductor materials like graphene, two-dimensional metal dichalcogenides, decorated with different nanoparticles with appropriate functionalization. © 2021 Elsevier B.V.

Sensors and Actuators, A: Physical

Development of semiconductor based heavy metal ion sensors for water analysis: A review

Gas sensor technology is widely utilized in various areas ranging from home security, environment and air pollution, to industrial production. It also hold great promise in non-invasive exhaled breath detection and an essential device in future internet of things. The past decade has witnessed giant advance in both fundamental research and industrial development of gas sensors, yet current efforts are being explored to achieve better selectivity, higher sensitivity and lower power consumption. The sensing layer in gas sensors have attracted dominant attention in the past research. In addition to the conventional metal oxide semiconductors, emerging nanocomposites and graphene-like two-dimensional materials also have drawn considerable research interest. This inspires us to organize this comprehensive 2020 gas sensing materials roadmap to discuss the current status, state-of-the-art progress, and present and future challenges in various materials that is potentially useful for gas sensors. © 2021 IOP Publishing Ltd.

Journal of Physics Condensed Matter

Gas sensing materials roadmap

In this article, we report the synthesis techniques of ZnO nanoparticles (NPs) in open air atmosphere by pulse laser ablation (PLA) method using solid ZnO polycrystalline palette followed by fabrication of formaldehyde (HCHO) sensor. The crystalline phase and morphology of the obtained ZnO NPs were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The XRD patterns showed that the NPs were polycrystalline structure with good crystallinity. The FESEM images revealed that the NPs were spherical in shape and loosely agglomerated. The average diameter of the NPs was in the range of 30-43 nm. Moreover, the ZnO NPs-based sensor exhibited excellent formaldehyde sensing performance at a temperature of 350 °C. The sensor exhibited a gas response of about 5.2 toward 300 ppm formaldehyde with 25 s response and 12 s recovery time. Furthermore, the ZnO NPs-based sensor exhibited excellent reliability and reproducibility to formaldehyde. On the other hand, the sensor showed high sensitivity of about 0.2% ppm {-{1}} to formaldehyde with a 50 ppm lower detection limit. In addition, the sensor showed an excellent linear relationship ( {R} {{2}} = {0.7948} ) between the response and the concentration of formaldehyde in the range of 50-400 ppm. This work demonstrates that PLA in open air is a rapid and cost-effective method for synthesizing metal oxide NPs for gas-sensing applications without the need for wet chemical routes. © 1963-2012 IEEE.

IEEE Transactions on Electron Devices

Fabrication of Fast and Reliable Pulse Laser-Ablated ZnO Nanoparticles-Based Formaldehyde Sensor

We have demonstrated a highly sensitive novel platform for real-time detection of Mercury (Hg2+) ions after successfully making silver nanowires (AgNWs)-MoS2 nanocomposite and functionalizing it over ungated AlGaN/GaN high electron mobility transistor (HEMT). The AlGaN/GaN HEMT structures were grown over the sapphire substrate using Molecular Beam Epitaxy. AgNWs-MoS2 nanocomposites were optimized for the device functionalization and 1:4 ratio was found highly sensitive for Hg2+ ions. The sensor exhibits high sensitivity towards Hg2+ ions of 1.604 mA/ppb and calculated its Limit of Detection (LoD) up to the range of 20 ppt. The observed sensitivity is highest among previously reported AlGaN/GaN fabricated HEMT based sensors for Mercury (Hg2+) ions detection and is well below the standard permissible limits as set by World Health Organization (WHO) and Environmental Protection Agency (EPA). The enhancement in sensitivity is due to the enhanced surface to volume ratio of AgNW-MoS2 nanocomposite and the highly conductive nature of silver nanowires incorporated in MoS2. Moreover, we also performed sensing on real water samples of tap water and lake water. Further, we showed the smart sensing capability of our developed sensor by illustrating the Internet of Things (IoT) enabled system for next-generation heavy metal ion sensing. IEEE

Department of Mechanical Engineering

IEEE Internet of Things Journal

Mercury (II) Ion Detection using AgNWs-MoS2 Nanocomposite on GaN HEMT for IoT Enabled Smart Water Quality Analysis

In this work, a control technique based on self acculturative damped (SAD) filter for solar photovoltaic energy conversion systems tied to the grid is presented. Its performance is evaluated in a single-phase single-stage configuration. Initially, the power requirements of a nonlinear load at the grid side is fulfilled and the superfluous extra power is fed into grid network. The primary intention of the technique is to fully utilize the effectuated power from the PV module and fulfill the active power demand in the grid side even during adverse grid conditions. The InC method is employed for the operation of maximum power point tracking (MPPT). The performance is evaluated with the help of simulation on SIMULINK MATLAB. The results entail that IEEE-519 is followed strictly by the control scheme and also shows its excellent performance. © 2021 IEEE.

2021 International Conference on Sustainable Energy and Future Electric Transportation, SeFet 2021

Control Scheme for Single Phase Single Stage Solar PV Energy Conversion System

The prime facets for the control of grid integrated voltage source converters (VSC) during abnormal grid variations are the control of voltage as well as power quality. In this article, a unique control strategy is presented for the control of solar photovoltaic (PV) system interfaced to the grid utilizing an interweaved generalized integrator. A single-stage three-phase topology is considered. The primary purpose of control is to deliver the PV power to the grid even during various abnormal grid variations. During normal operation, the system delivers power at unity power factor. However, during variations in the grid voltage, the profile of the PCC voltage is maintained within prescribed limits by reactive power injection. Moreover, LVRT operation is undertaken during severe voltage sags. The utilization of the system is increased in the absence of PV generation during night, the VSC and dc link capacitor act as a distribution static compensator. Contrary to traditional control techniques, power quality of the system is not compromised. The achievements of the control are demonstrated through simulation as well as with hardware implementation. Furthermore, a comparative analysis, with the state-of-the-art techniques, is highlighted, which shows the efficacy of the presented control. © 1982-2012 IEEE.

IEEE Transactions on Industrial Electronics

A Voltage Support Control Strategy for Grid Integrated Solar PV System during Abnormal Grid Conditions Utilizing Interweaved GI

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.

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.