Corrosion Inhibitive and Adsorption Properties of a Flavonoid compound for Mild Steel in Acidic Medium

Ezhilarasi, J. Christy,Nagarajan, Prabavathy Korean Chemical Society 2011 대한화학회지 Vol.55 No.3

플라보노이드계 화합물인 HMPC (3-hydroxy-7-methoxy-2-phenylchromen-4-one의 부식억제성질, HMPC와 TBAB(n-tetrabutylammonium bromide) 간 상승효과, 염산 조건하 부드러운 강철의 흡착성질을 무게 감량, 변전위 편극, 전기화학 임피던스 분광기를 사용하여 연구하였다. 다양한 온도에서 무게 감량 측정 실험한 결과 부식 억제 효율은 억제제 농도가 증가함에 따라 증가하였고, 계의 온도가 증가함에 따라 감소하였다. 전기화학 실험 결과 부식 억제는 여러 혼합된 형태의 억제 방법에 의해 가능하였다. 금속 표면에 흡착된 억제 화합물 분자는 보호막을 형성하였다. The corrosion inhibitive nature of a flavonoid compound, 3-Hydroxy-7-methoxy-2-phenylchromen-4-one (HMPC), the synergistic effect between HMPC and n-Tetrabutylammonium bromide (TBAB) and their adsorption behavior on mild steel in hydrochloric acid solution were studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results of weight loss study at different temperatures revealed that the inhibition efficiency increases with inhibitor concentration and decreases with increase in the temperature of the system. The electrochemical studies showed that the inhibitor acts through mixed mode of inhibition and the inhibitor molecules adsorb on the metal - solution interface forming a protective layer. The adsorption of the inhibitor molecules over the metal surface was supported by the obeyed Langmuir's adsorption isotherm, Scanning Electron Microscopic analysis (SEM) and Fourier Transform Infrared (FT-IR) spectroscopic studies.

Modeling and Evaluation of Adaptive Super Twisting Sliding Mode Control in Lower Extremity Exoskeleton

D. Ezhilarasi,Anjali S. Nair 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.8 No.3

In this paper, an integrated human-in-the-loop simulation paradigm for the design and performance analysis of a 6 DOF lower extremity exoskeleton is presented. An adaptive Super Twisting Sliding Mode Controller (ASTSMC) is designed for the trajectory tracking control of the exoskeleton by considering the human motion as reference trajectory. The dynamic model, that include linear and rotational displacement of hip, knee and ankle joints of both the legs is developed using Lagrange energy formulation. The position and angular velocity error of the wearer and the exoskeleton are being considered to establish the control law. Super twisting SMC is a robust control scheme that works effectively in the presence of external disturbances and parameter variations. However, the STSMC introduces chattering in the closed loop because of its high gain, to overcome this drawback, an adaptive STSMC is proposed for the control of exoskeleton against unknown disturbances without chattering. An adaptation scheme using Lyapunov criterion is derived that ensures the stability of the system in closed loop. The performance of the proposed control strategy is verified by implementing on the integrated CAD model of the exoskeleton along with the wearer. The effectiveness of the controller is tested under wind disturbance of varying velocity and direction. The results demonstrate improved tracking performance of the proposed control scheme with least error and less control effort compared to constant gain STSMC in normal and uneven terrain.

Novel Synthesis of bis Acetylated Hybrid Pyrazoles as Potent Anticandidiasis Agents

Kanagarajan, V.,Ezhilarasi, M. R.,Gopalakrishnan, M. Korean Chemical Society 2011 대한화학회지 Vol.55 No.2

Bis acetylated hybrid pyrazoles 을 합성하여 이들 화합물에 대해 녹는점, 원소분석, MS, FT-IR, one-dimensional $^1H,-$ 및 $^{13}C$-NMR로 분석하였다. 합성한 화합물들에 대해 in vitro 항균활성을 Candida sp. namely Candida albicans, Candida glabrata, Candida parapsilosis, Candida dubliniensis 및 Candida tropicali 균에 대해 수행하였다. Pyrazoles의 페닐고리에 작용기($-CH_3$, $-OCH_3$, -F, -Cl, 및 Br)가 있는 화합물은 Candida species에 대해서 강한 활성을 나타내었다. A new series of bis acetylated hybrid pyrazoles were synthesized and characterized by their melting point, elemental analysis, MS, FT-IR, one-dimensional $^1H$, and $^{13}C$ NMR spectroscopic data. All the synthesized compounds were tested for their in vitro antifungal activities against Candida sp. namely Candida albicans, Candida glabrata, Candida parapsilosis, Candida dubliniensis and Candida tropicalis. A close inspection of the in vitro anticandidal activity profile in differently electron donating ($CH_3$ and $OCH_3$) and electron withdrawing (-F, -Cl, and Br) functional group substituted phenyl rings of novel hybrid pyrazoles exerted strong anticandidal activity against all the tested Candida species.

Performance Analysis of Super Twisting Sliding Mode Controller by ADAMS–MATLAB Co-simulation in Lower Extremity Exoskeleton

Anjali S. Nair,D. Ezhilarasi 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.3

Lower extremity exoskeleton is a kind of wearable robot and is used both in medical and industrial applications for diff erent purposes. In the medical fi eld it is used as a piece of therapeutic equipment and in the industry especially in defense, to carry heavy loads. This paper deals with the analysis of the performance of super twisting sliding mode controller (STSMC) on tracking the motion of the wearer by the lower extremity exoskeleton using automatic dynamic analysis of mechanical systems (ADAMS)–MATLAB co-simulation during walking and step climbing and the results are compared with a conventional PID controller. The model of the lower extremity exoskeleton is developed by solid-works software and the model of the human body is done with ADAMS software. Super twisting sliding mode controller (STSMC) is designed and simulated with Simulink. This paper also aims to develop a mathematical model of the system and analyze the performance of STSMC to control hip, knee, and ankle movements and also to point out the advantages of the ADAMS–MATLAB co-simulation over the conventional methods of modeling and simulation analysis of the controller to control the exoskeleton. Stability analysis of the controller is also done.

A Review of Acoustic Energy Harvesting

Minu A Pillai,Ezhilarasi Deenadayalan 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

Acoustic energy is an important form of energy which is generated and unused all around us. Despite the prevalence of acousticenergy a major challenge of energy harvesting is the low power density in typical acoustic noise fields. With a larger focus on greenenergy, acoustic energy is one of the vastly available energy sources and so harvesting this energy plays an important role in research. Unconventionally a thermoacoustic engine converts thermal energy to acoustic energy via its core, comprising a porous material thatis sandwiched between two heat exchangers. The induced acoustic wave can be converted into electricity by introducing novelenvironment friendly energy converters. Integration of the thermoacoustic technology with piezoelectricity tends to be promising, sincethe piezoelectric ceramics are sensitive and operating efficiently at high frequencies. Thermoacoustic technology is receiving growinginterest in research for its many advantages, such as having no moving parts, being environment friendly and the possibility of usingother renewable energy for its operation. This paper aims at providing a review on various acoustic and thermoacoustic energyharvesting techniques and the maximum power generated from each of these techniques.

Design and implementation of fast output sampling feedback control for shape memory alloy actuated structures

Dhanalakshmi, K.,Umapathy, M.,Ezhilarasi, D.,Bandyopadhyay, B. Techno-Press 2011 Smart Structures and Systems, An International Jou Vol.8 No.4

This paper presents the design and experimental evaluation of fast output sampling feedback controller to minimize structural vibration of a cantilever beam using Shape Memory Alloy (SMA) wires as control actuators and piezoceramics as sensor and disturbance actuator. Linear dynamic models of the smart cantilever beam are obtained using online recursive least square parameter estimation. A digital control system that consists of $Simulink^{TM}$ modeling software and dSPACE DS1104 controller board is used for identification and control. The effectiveness of the controller is shown through simulation and experimentation by exciting the structure at resonance.

Cantilever Beam with Trapezoidal Cavity for Improved Energy Harvesting

Annapureddy Rami Reddy,Mangalanathan Umapathy,Deenadayalan Ezhilarasi,Gandhi Uma 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.

This paper presents a cantilever structure as energy harvester by introducing a trapezoidal cavity to increase the amplitude of the generated voltage and the overall mechanical to electrical energy conversion efficiency. An analytical model of the proposed structure is developed using Euler-Bernoulli beam theory. The effect of taper angle of the trapezoidal cavity and the neutral axis shift on the generated voltage is analyzed using analytical model and through experimentation. The generated output voltage from the energy harvester with trapezoidal cavity is compared with the beam having rectangular cavity and the beam without cavity. The generated voltage for the beam with trapezoidal cavity is 97.5% and 108% higher as compared with the beam having rectangular cavity and the beam without cavity. The characteristics of the energy harvester are evaluated through analytical model and experimentation and the results are in close agreement.

Design and implementation of fast output sampling feedback control for shape memory alloy actuated structures

K. Dhanalakshmi,M. Umapathy,D. Ezhilarasi,B. Bandyopadhyay 국제구조공학회 2011 Smart Structures and Systems, An International Jou Vol.8 No.4

This paper presents the design and experimental evaluation of fast output sampling feedback controller to minimize structural vibration of a cantilever beam using Shape Memory Alloy (SMA) wires as control actuators and piezoceramics as sensor and disturbance actuator. Linear dynamic models of the smart cantilever beam are obtained using online recursive least square parameter estimation. A digital control system that consists of Simulink modeling software and dSPACE DS1104 controller board is used for identification and control. The effectiveness of the controller is shown through simulation and experimentation by exciting the structure at resonance.

Modelling and experimental investigations on stepped beam with cavity for energy harvesting

A. Rami Reddy,M. Umapathy,D. Ezhilarasi,G. Uma 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.4

This paper presents techniques to harvest higher voltage from piezoelectric cantilever energy harvester by structural alteration. Three different energy harvesting structures are considered namely, stepped cantilever beam, stepped cantilever beam with rectangular and trapezoidal cavity. The analytical model of three energy harvesting structures are developed using Euler-Bernoulli beam theory. The thickness, position of the rectangular cavity and the taper angle of the trapezoidal cavity is found to shift the neutral axis away from the surface of the piezoelectric element which in turn increases the generated voltage. The performance of the energy harvesters is evaluated experimentally and is compared with regular piezoelectric cantilever energy harvester. The analytical and experimental investigations reveal that, the proposed energy harvesting structures generate higher output voltage as compared to the regular piezoelectric cantilever energy harvesting structure. This work suggests that through simple structural modifications higher energy can be harvested from the widely reported piezoelectric cantilever energy harvester.