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Showing papers by "Shantanu Das published in 2020"


Journal ArticleDOI
TL;DR: An online FOM for supercapacitors is presented, which employs a two-stage least square fitting algorithm for identifying the parameters in real time and is implemented using Grunwald–Letnikov derivative in a DSP and the effectiveness is verified.
Abstract: Supercapacitors exhibit different capacitance values under varying operating conditions, due to the porous nature of their electrodes. As a result, the conventional resistor-capacitor (R-C) model or ladder R-C network models fail to accurately represent the dynamics of the supercapacitors. Fractional-order models (FOMs) that have been utilized in recent times, to represent these dynamics are more accurate. But, they too, are prone to inaccuracies because their parameters vary due to the changes in the operating voltage, current, and frequency. To address this issue, this article presents an online FOM for supercapacitors, which employs a two-stage least square fitting algorithm for identifying the parameters in real time. The first stage of the algorithm identifies the derivative order, “α” whereas the second stage calculates the capacitance and resistance values based on the voltage and current measurements. The proposed online FOM is implemented using Grunwald–Letnikov derivative in a DSP and the effectiveness is verified with experimental results. Furthermore, comparison of the online FOM with an existing offline FOM for state of charge estimation is presented. Additionally, certain issues related to the choice of the initial values and sampling time, encountered in the real time implementation of the proposed FOM, are also reported.

19 citations


Journal ArticleDOI
TL;DR: This paper describes how the experiments on fractional calculus can be tailored for graduate, undergraduate students’ education and extended for research in this emerging area.
Abstract: In this paper, a novel prototype laboratory is presented for engineering education, in which experiments are based on the fractional calculus. The prototypes of analog and digital fractional-order ...

15 citations


Journal ArticleDOI
TL;DR: A fractional calculus-based approach is proposed for modeling the hysteresis and estimating the related remnant voltage and associated energy availability after the completion of periodic charging excitations, thus providing a platform for improving the energy efficiency of the ultracapacitor-based energy management applications by optimal charging.
Abstract: The rough and porous structure of the electrode and electrolyte interface in ultracapacitors results in hysteresis between the excitation current and corresponding terminal voltage. The hysteretic behavior causes an increment in terminal voltage even after the removal of input excitation current, referred to as remnant voltage. The design and operation of any ultracapacitor-based energy system should necessarily take into account the hysteretic behavior and the associated remnant voltage for optimal utilization of ultracapacitor as a storage device. Proper modeling of hysteresis allows for determining the optimal excitation profile for charging the ultracapacitor, such that proper balance between the load demand and energy storage is achieved. Motivated by the effectiveness of fractional calculus in representing the long-term memory effect and charge diffusion phenomena in ultracapacitors, this article proposes a fractional calculus-based approach for modeling the hysteresis and estimating the related remnant voltage and associated energy availability after the completion of periodic charging excitations. Analytical expressions for ultracapacitor voltage and energy storage have been formulated for different hysteresis levels using fractional calculus. The formulation helps in quantifying the hysteresis as a function of the excitation magnitude/duration and ultracapacitor model parameters, thus providing a platform for improving the energy efficiency of the ultracapacitor-based energy management applications by optimal charging. The derived expressions have been experimentally validated for varying dynamics of current excitation.

8 citations


Journal ArticleDOI
TL;DR: In this article, the electrical properties of a composite solid polymer electrolyte (SPE) consisting of poly(ethylene oxide), polyvinylidene fluoride, and 35 wt.
Abstract: A solid polymer electrolyte (SPE) film with improved mechanical and thermal stability has drawn significant attention in the field of polymer research due to their technological applications in energy storage devices. We have explored the electrical properties of the blend SPE composed of 20 wt. % poly(ethylene oxide), 80 wt. % polyvinylidene fluoride, and 35 wt. % NH4I by introducing a plasticizer ethylene carbonate (EC). A significant enhancement of electrical conductivity has been found in the composite SPE containing 80 wt. % of EC. We have confirmed the formation of a hydrogen bonding network between the carbonyl group (C=O) of EC and the cations NH4+. Therefore, EC facilitates the new coordination sites via the hydrogen bonding network with the cations NH4+, which eventually leads to the enhancement of conductivity up to a maximum value of 1.2 × 10−4 S/cm at 80 wt. % of EC. The increase in the relative percentage of contact ions over free ions at 80% of EC, as estimated from the FTIR study, is thus intriguing. Therefore, we have proposed an ion transport mechanism based on ion hopping through different coordinating sites mediated by EC. Dielectric relaxation of the composite SPE has been best delineated by a two-parameter Mittag-Leffler function. The exponents obtained from the fit of the experimental decay function with the two-parameter Mittag-Leffler function in the entire time domain are positive and less than one, suggesting non-Debye relaxation in the polymer composite system under investigation.

6 citations



Journal ArticleDOI
01 Dec 2020-Pramana
TL;DR: In this article, a fractional Klein-Gordon equation with fractional vector and scalar potential has been studied, where both fractional potentials are taken as attractive Coulomb-type with different multiplicative parameters, namely v and s. This manipulation delivers fractional-type confluent hypergeometric equation to solve.
Abstract: D-dimensional fractional Klein–Gordon equation with fractional vector and scalar potential has been studied. Both fractional potentials are taken as attractive Coulomb-type with different multiplicative parameters, namely v and s. Jumarie-type definitions for fractional calculus have been used. We have succeeded in achieving Whittaker-type classical differential equation in fractional mode for the required eigenfunction. Fractional Whittaker equation has been manipulated using the behaviour of the eigenfunction at asymptotic distance and origin. This manipulation delivers fractional-type confluent hypergeometric equation to solve. Power series method has been employed to do the task. All the obtained results agree with the existing results in literature when fractional parameter $$\alpha $$ is unity. Finally, we furnish numerical results with a few eigenfunction graphs for different spatial dimensions and fractional parameters.

3 citations


Journal ArticleDOI
TL;DR: In this article, a commercial steel-alloyed drill tool has been used as a microwave concentrator and was characterized after the microwave drilling process to investigate the practicability of drilling sub-millimeter holes in the low-melting-point Perspex using microwave energy.
Abstract: An attempt was made to investigate the practicability of drilling sub-millimeter holes in the low–melting-point Perspex using microwave energy. However, a complete characterization study of the microwave drilling process occurs through the characterization of the drill concentrator and the drilled hole in the Perspex specimen. In the present study, a commercial steel-alloyed drill tool has been used as a microwave concentrator and was characterized after the microwave drilling process. The key objective was to understand the capability of the drill tool in concentrating the microwave energy for effective hole drilling in Perspex specimens. A method based on mutual material interaction inside a customized applicator was employed to drill a hole in Perspex by thermal ablation. Energy dispersive spectroscopy using a field emission scanning electron microscopy was performed on a drill tool and workpiece to understand the composition variation during microwave drilling. A Dewinter optical microscope with material and software was used for macroscopic studies (Dewinter, New Delhi, India). Often, a precise weighing machine, jiffy digital clock, and fluke infrared thermometer were used for basic preparation. Thermal analyses based on thermogravimetric analysis (thermogravimetric analysis, differential thermal analyzer, and derivative thermogravimetric) were attempted in order to understand the thermal losses and heat energy influencing the performance of the microwave drilling process. Thermal characterization was carried out for the high heating rates of individual materials as well as the interaction with other materials. The results confirm the drilling of a hole at a low power (90–360 W) setting by a steel alloy drill bit concentrator. It was observed that the melting of the drill bit increased with an increase in the power beyond 180 W. A quality hole of 0.9 mm was drilled with a 0.8 mm drill bit after material characterization at optimized parametric settings.

2 citations


Journal ArticleDOI
TL;DR: In this paper, the main goal is to find the approximate solution of the space-time fractional order KdV (STFKdV) equation and Coupled kdV equation by using Homotopy analysis method (HAM).
Abstract: The main goal of this article is to find the approximate solution of the space-time fractional order KdV (STFKdV) equation and Coupled KdV (STFCKdV) equations by using Homotopy analysis method (HAM...

2 citations


Journal ArticleDOI
TL;DR: In this article, the authors used fractional calculus to find left and right fractional derivatives at those non-differentiable points and then predict LVH and RVH by calculating the phase transition values.
Abstract: In this paper we have studied Left and Right ventricular hypertrophy of heart from ECGs using fractional calculus. An ECG is a rough or unreachable curve which is continuous everywhere but nondifferentiable at some points or all points where classical calculus fails. Our purpose of this paper is to find left and right fractional derivatives at those non-differentiable points and then predict LVH and RVH by calculating the phase transition values (absolute difference of left and right fractional derivatives). Our investigation shows that for LVH patients the phase transition values at the non-differentiable points of V1, V2, V5 and V6 leads are higher than those for normal ECG. For RVH ECG the phase transition values at S are smaller than those of R in V1 leads which are just opposite to the case of normal ECGs. Fractal dimension and Hurst Exponents of V1, V2, V5 and V6 leads of the ECGs have been calculated for both problematic and normal ECGs. All such measures may help doctors to diagnose LVH and RVH from ECG more accurately than the technique they use.

1 citations