Fuzzy sliding mode control design of Markovian jump systems with time-varying delay

Sakthivel, R.,Sakthivel, R.,Nithya, V.,Selvaraj, P.,Kwon, O.M. Elsevier 2018 Journal of the Franklin Institute Vol.355 No.14

<P><B>Abstract</B></P> <P>This paper studies the robust stochastic stabilization problem for a class of fuzzy Markovian jump systems with time-varying delay and external disturbances via sliding mode control scheme. Based on the equivalent-input-disturbance (EID) approach, an online disturbance estimator is implemented to reject the unknown disturbance effect on the considered system. Specifically, to obtain exact EID estimation Luenberger fuzzy state observer and a low-pass filter incorporated to the closed-loop system. Moreover, novel fuzzy EID-based sliding mode control law is constructed to ensure the stability of the closed-loop system with satisfactory disturbance rejection performance. By employing Lyapunov stability theory and some integral inequalities, a new set of delay-dependent robust stability conditions is derived in terms of linear matrix inequalities (LMIs). The resulting LMI is used to find the gains of the state-feedback controller and the state observer a for the resulting closed-loop system. At last, numerical simulations based on the single-link arm robot model are provided to illustrate the proposed design technique.</P>

Finite-time synchronization of stochastic coupled neural networks subject to Markovian switching and input saturation

Selvaraj, P.,Sakthivel, R.,Kwon, O.M. Elsevier 2018 Neural networks Vol.105 No.-

<P><B>Abstract</B></P> <P>This paper addresses the problem of finite-time synchronization of stochastic coupled neural networks (SCNNs) subject to Markovian switching, mixed time delay, and actuator saturation. In addition, coupling strengths of the SCNNs are characterized by mutually independent random variables. By utilizing a simple linear transformation, the problem of stochastic finite-time synchronization of SCNNs is converted into a mean-square finite-time stabilization problem of an error system. By choosing a suitable mode dependent switched Lyapunov–Krasovskii functional, a new set of sufficient conditions is derived to guarantee the finite-time stability of the error system. Subsequently, with the help of anti-windup control scheme, the actuator saturation risks could be mitigated. Moreover, the derived conditions help to optimize estimation of the domain of attraction by enlarging the contractively invariant set. Furthermore, simulations are conducted to exhibit the efficiency of proposed control scheme.</P>

Disturbance and uncertainty rejection performance for fractional-order complex dynamical networks

Selvaraj, P.,Kwon, O.M.,Sakthivel, R. Elsevier 2019 Neural networks Vol.112 No.-

<P><B>Abstract</B></P> <P>This paper investigates the synchronization issue for a family of time-delayed fractional-order complex dynamical networks (FCDNs) with time delay, unknown bounded uncertainty and disturbance. A novel fractional uncertainty and disturbance estimator (FUDE) based feedback control strategy is proposed to not only synchronize the considered FCDNs but also guaranteeing the precise rejection of unmodelled system uncertainty and external disturbance. Especially, in FUDE-based approach, model uncertainties and external disturbance are integrated as a lumped disturbance and it does not require a completely known system model or a disturbance model. On the other hand, the design algorithm for the proposed control strategy is based on the state-space framework, rather than frequency-based design methodologies in the literature, which helps for predominant comprehension of the inner system behaviour. Also, by the temperance of Lyapunov stability theory and fractional calculus, a set of adequate conditions in the linear matrix inequality framework is obtained, which guarantees the robust synchronization of the closed-loop system. Furthermore, an iterative optimization algorithm is proposed to improve control robustness against the external disturbance and model uncertainties. Finally, two numerical illustrations including financial network model, where the influence of adjustment of macro-economic policies in the entire financial system are given to exhibit the rightness and important features of the acquired theoretical results.</P>

A vacuum pressure sensor based on graphene/ZnO nanorod Schottky junction

Sakthivel P.,Ramachandran K.,Malarvizhi M.,Karuppuchamy S.,Manivel P. 한국탄소학회 2024 Carbon Letters Vol.34 No.1

We present a practical vacuum pressure sensor based on the Schottky junction using graphene anchored on a vertically aligned zinc oxide nanorod (ZnO-NR). The constructed heterosystem of the Schottky junction showed characteristic rectifying behavior with a Schottky barrier height of 0.64 eV. The current–voltage (I–V) features of the Schottky junction were measured under various pressures between 1.0 × 103 and 1.0 × 10−3 mbar. The maximum current of 38.17 mA for the Schottky junction was measured at – 4 V under 1.0 × 10−3 mbar. The high current responses are larger than those of the previously reported vacuum pressure sensors based on ZnO nanobelt film, ZnO nanowires, and vertically aligned ZnO nanorod devices. The pressure-sensitive current increases with the vacuum pressure and reaches maximum sensitivity (78.76%) at 1.0 × 10−3 mbar. The sensitivity and repeatability of the Schottky junction were studied by the current–time (I–T) behavior under variation of vacuum pressure. The sensing mechanism is debated from the surface charge transfer doping effect by oxygen chemisorption. The results suggest that this simple graphene/ZnO-NR Schottky junction device may have potential in the fabrication of vacuum pressure sensor with high sensitivity.

Adaptive reliable output tracking of networked control systems against actuator faults

Sakthivel, R.,Selvaraj, P.,Lim, Y.,Karimi, H.R. Pergamon 2017 Journal of the Franklin Institute Vol. No.

<P>This paper investigates the reliable adaptive observer-based output tracking control problem for a class of networked control systems subject to actuator faults and external disturbances via equivalent-input disturbance technique. Notably, the reliable control design based on adaptive mechanism is implemented to compensate the on-line actuator faults automatically and an observer-based controller is introduced through communication networks to drive the output of controlled plant to track the output of a reference model. Moreover, due to the effect of network-induced delays and packet dropouts in the controller-to-actuator channel, the inputs of controlled plant and observer-based tracking controller are updated in an asynchronous way. Then, based on the asynchronous characteristic, the resulting closed-loop networked control system is formulated with two interval time-varying delays for obtaining the required result. In particular, the equivalent-input disturbance approach improves the disturbance rejection performance and it does not require any prior knowledge of the disturbances. By constructing a suitable Lyapunov-Krasovskii functional and using free-weighting matrix approach, a new set of sufficient conditions for the solvability of the addressed problem is derived in terms of linear matrix inequalities. At last, the proposed result is validated through two numerical examples and also a comparison study is presented which shows the effectiveness of the developed control scheme over some existing conventional control schemes. (C) 2016 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.</P>

Vibration control of structural systems via robust non-fragile sampled-data control scheme

Sakthivel, R.,Aravindh, D.,Selvaraj, P.,Kumar, S.V.,Anthoni, S.M. Pergamon 2017 Journal of the Franklin Institute Vol. No.

<P>This paper investigates the dissipative non-fragile output feedback sampled-data control problem for uncertain structural systems. In the proposed system, uncertainties are assumed to be time-varying and bounded, which are considered in the linear fractional transformation form. The main objective of this paper is to design a non-fragile sampled-data controller such that the resulting closed-loop system is strictly (Q,S,R)-alpha-dissipative. On the basis of a suitable Lyapunov Krasovskii functional and linear matrix inequality technique, a new set of sufficient conditions is established to achieve the required result for both nominal and uncertain systems. In particular, an output feedback dissipative sampled-data controller is designed by solving a set of matrix inequalities. More precisely, Schur complement lemma, free weighting matrix approach and Wirtinger-based double integral inequality are utilized to substantially simplify the derivation of the main results. Finally, simulations based on structural systems are conducted to illustrate the effectiveness of the proposed control scheme. (C) 2016 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.</P>

Impact Strength of Hybrid Steel Mesh-and-Fiber Reinforced Cementitious Composites

P. B. Sakthivel,A. Ravichandran,N. Alagamurthi 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.5

Large volumes of concrete are produced for construction purposes which creates sustainability issues. Therefore, some of the alternatives to concrete that are being researched and implemented are Steel Mesh Reinforced Cementitious Composites (SMRCC) and Fiber Reinforced Cementitious Composites (FRCC). But due to limitations in element thickness and volume percentage of reinforcement in SMRCC and FRCC, this study has made an attempt to develop Hybrid Steel Mesh-and-Fiber Reinforced Cementitious Composites (HSMFRCC) and study its impact performance. Thus, in order to evaluate the energy absorption of HSMFRCC, 250 mm × 250 mm × 25 mm (thick) slab elements were cast with various combinations of 3-5 layers of steel weld mesh and SS fibers of 0.5-2.5% (of volume of specimens) and low velocity repeated drop weight impact test was administered. From the experimental results, it was found that the impact resistance of HSMFRCC (test specimens) is higher than SMRCC (control specimens using only steel mesh as reinforcement). Regression models have been developed in this study and validated using new hybrid mesh and fiber reinforcement mix. The predicted regression equations developed for initial and ultimate impact energy absorption of cementitious composites with hybrid steel mesh and fibers will be quite useful to the practitioners.

Development of Dye-SensitizedSolar Cells Composed of Liquid Crystal Embedded, Electrospun Poly(vinylidenefluoride-<i>co</i>-hexafluoropropylene) Nanofibers as PolymerGel Electrolytes

Ahn, Sung Kwang,Ban, Taewon,Sakthivel, P.,Lee, Jae Wook,Gal, Yeong-Soon,Lee, Jin-Kook,Kim, Mi-Ra,Jin, Sung-Ho AmericanChemical Society 2012 ACS APPLIED MATERIALS & INTERFACES Vol.4 No.4

<P>In order to overcome the problems associated with the use of liquid electrolytes in dye-sensitized solar cells (DSSCs), a new system composed of liquid crystal embedded, polymer electrolytes has been developed. For this purpose, three types of DSSCs have been fabricated. The cells contain electrospun poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVdF-co-HFP) polymer gel electrolyte, with and without doping with the liquid crystal E7 and with a liquid electrolyte. The morphologies of the newly prepared DSSCs were explored using field emission scanning electron microscopy (FE-SEM). Analysis of the FE-SEM images indicate that the DSSC composed of E7 embedded on e-PVdF-co-HFP polymer gel electrolyte has a greatly regular morphology with an average diameter. The ionic conductivity of E7 embedded on e-PVdF-co-HFP polymer gel electrolyte was found to be 2.9 X 10(-3) S/cm at room temperature, a value that is 37% higher than that of e-PVdF-co-HFP polymer gel electrolyte. The DCCS containing the E7 embedded, e-PVdF-co-HFP polymer gel electrolyte was observed to possess a much higher power conversion efficiency (PCE = 6.82%) than that of an e-PVdF-co-HFP nanofiber (6.35%). In addition, DSSCs parameters of the E7 embedded, e-PVdF-co-HFP polymer gel electrolyte (V-oc = 0.72 V, J(sc) = 14.62 mA/cm(2), FF = 64.8%, and PCE = 6.82% at 1 sun intensity) are comparable to those of a liquid electrolyte (V-oc = 0.75 V, J(sc) = 14.71 mA/cm(2), FF = 64.9%, and PCE = 7.17%, both at a 1 sun intensity).</P>

Reliable anti-synchronization conditions for BAM memristive neural networks with different memductance functions

Sakthivel, R.,Anbuvithya, R.,Mathiyalagan, K.,Ma, Y.K.,Prakash, P. Elsevier [etc.] 2016 Applied mathematics and computation Vol.275 No.-

<P>This paper is concerned with anti-synchronization results for a class of memristor-based bidirectional associate memory (BAM) neural networks with different memductance functions and time-varying delays. Based on drive-response system concept, differential inclusions theory and Lyapunov stability theory, some sufficient conditions are obtained to guarantee the reliable asymptotic anti-synchronization criterion for memristor-based BAM networks. The memristive BAM neural network is formulated for two types of memductance functions. Sufficient results are derived in terms of linear matrix inequalities (LMIs). Finally, the effectiveness of the proposed criterion is demonstrated through numerical example. (C) 2015 Elsevier Inc. All rights reserved.</P>

Passivity of memristor-based BAM neural networks with different memductance and uncertain delays

Anbuvithya, R.,Mathiyalagan, K.,Sakthivel, R.,Prakash, P. Springer Science + Business Media 2016 COGNITIVE NEURODYNAMICS - Vol.10 No.4

<P>This paper addresses the passivity problem for a class of memristor-based bidirectional associate memory (BAM) neural networks with uncertain time-varying delays. In particular, the proposed memristive BAM neural networks is formulated with two different types of memductance functions. By constructing proper Lyapunov-Krasovskii functional and using differential inclusions theory, a new set of sufficient condition is obtained in terms of linear matrix inequalities which guarantee the passivity criteria for the considered neural networks. Finally, two numerical examples are given to illustrate the effectiveness of the proposed theoretical results.</P>