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Rajagopal Karthikeyan,Kingni Sifeu Takougang,Kom Guillaume Honoré,Pham Viet-Thanh,Karthikeyan Anitha,Jafari Sajad 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.2
A chaotic simple jerk system (SJS) that belongs to systems with self-excited and hidden attractors is introduced in this paper. The dynamics of the proposed SJS is analytically and numerically investigated. Interestingly, the influence of the time delay on the proposed chaotic SJS is studied. In addition, the physical existence of self-excited and hidden chaotic attractors found in the proposed SJS and in the time-delayed form of SJSs (TDSJSs) are verified by using Orcard-PSpice software. Finally, chaos synchronization of identical, unidirectional, coupled, proposed chaotic TDSJSs is also reported.
Optimization of active area of proton exchange membrane fuel cell with better water management
M. Karthikeyan,M. Muthukumar,P. Karthikeyan,C. Mathan 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.5
Water flooding is one of the major issues which is influencing the performance of PEMFC, while scaling up the active area. Water accumulation in between the GDL and cathode flow field landing in PEMFC can be removed by fixing porous inserts along the landing area of the cathode flow field. In this paper, the optimum active area of the PEMFC is found from the experimental investigations of three active area sizes of 25 cm2, 36 cm2 and 70 cm2 with better water management by fixing porous inserts along the landing surface. All three active areas of PEMFCs with three different flow fields viz. Serpentine; Uniform and Stagger patterned pin types having porous inserts on cathode side have been investigated experimentally. The PEMFCs with active area of 25 cm2, 36 cm2 and 70 cm2 with stagger patterned pin types having porous inserts have obtained maximum power densities as 0.270 W/cm2, 0.338 W/cm2and 0.170 W/cm2 respectively. The PEMFC with active area of 36 cm2 yields higher power density compared to 25 cm2 and 70 cm2 PEMFCs. So it is found that the active area of 36 cm2 is the optimum active area of single cell PEMFC for maximum performance.
KARTHIKEYAN, K.,RAJA, D. SENTHIL,SUNDARARAJAN, P. The Korean Society for Computational and Applied M 2022 Journal of applied mathematics & informatics Vol.40 No.1-2
We study the existence and uniqueness of solutions for a class of boundary value problems of nonlinear fractional order differential equations involving the Caputo fractional derivative by employing the Banach's contraction principle and the Schauder's fixed point theorem. In addition, an example is given to demonstrate the application of our main results.
Karthikeyan, Kaliyappan,Amaresh, Samuthirapandian,Son, Ju-Nam,Kim, Shin-Ho,Kim, Min-Chul,Kim, Kwang-Jin,Lee, Sol-Nip,Lee, Yun-Sung Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.1
Layered $Li_{1+x}(Mn_{0.4}Ni_{0.4}Fe_{0.2})_{1-x}O_2$ (0 < x < 0.3) solid solutions were synthesized using solgel method with adipic acid as chelating agent. Structural and electrochemical properties of the prepared powders were examined by means of X-ray diffraction, Scanning electron microscopy and galvanostatic charge/discharge cycling. All powders had a phase-pure layered structure with $R\bar{3}m$ space group. The morphological studies confirmed that the size of the particles increased at higher x content. The charge-discharge profiles of the solid solution against lithium using 1 M $LiPF_6$ in EC/DMC as electrolyte revealed that the discharge capacity increases with increasing lithium content at the 3a sites. Among the cells, $Li_{1.2}(Mn_{0.32}Ni_{0.32}Fe_{0.16})O_2$ (x = 0.2)/$Li^+$ exhibits a good electrochemical property with maximum initial capacity of 160 $mAhg^{-1}$ between 2-4.5 V at 0.1 $mAcm^{-2}$ current density and the capacity retention after 25 cycles was 92%. Whereas, the cell fabricated with x = 0.3 sample showed continuous capacity fading due to the formation of spinel like structure during the subsequent cycling. The preparation of solid solutions based on $LiNiO_2-LiFeO_2-Li_2MnO_3$ has improved the properties of its end members.
Karthikeyan, K.,Kannan, S.,Baskar, S.,Thangaraj, C. The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.4
Generation Expansion Planning (GEP) is one of the most important decision-making activities in electric utilities. Least-cost GEP is to determine the minimum-cost capacity addition plan (i.e., the type and number of candidate plants) that meets forecasted demand within a pre specified reliability criterion over a planning horizon. In this paper, Differential Evolution (DE), and Opposition-based Differential Evolution (ODE) algorithms have been applied to the GEP problem. The original GEP problem has been modified by incorporating Virtual Mapping Procedure (VMP). The GEP problem of a synthetic test systems for 6-year, 14-year and 24-year planning horizons having five types of candidate units have been considered. The results have been compared with Dynamic Programming (DP) method. The ODE performs well and converges faster than DE.
Numerical modelling of dry-out in pulsating heat pipe using VOF model
Karthikeyan Cheiyar Palani,Deepakkumar Rajagopal 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
Operational limits are critical in the continuous functioning of a pulsating heat pipe (PHP). A computational fluid dynamics study was conducted to analyze the influence of working-fluid properties on the dry-out limit of closed-loop water-based PHP with a 50 % fill ratio. Working fluid (water) was boiled decisively at low temperature (35 °C) under reduced operating pressures to ease and analyze dry-out. Although, vapor pressure of water at 35 °C is 5.6 kPa; different evacuated pressures ranging from 2 to 10 kPa were attempted to validate the numerical model using different boiling characteristics and their influence on the dry-out phenomena. 2-D transient pressure based Navier-Stokes solver (ANSYS Fluent) was used to predict the field variables using the SIMPLE algorithm. The standard k-ϵ model with the enhanced wall treatment approach was used to capture the turbulent physics. VOF model was used to shape the two-phase flow characteristics. The adiabatic section was noticed to act as a functional barrier (for the pressure drop to occur) between evaporator and condenser sections. New concepts such as inverse flow dynamics, zero-gradient and equivalent points were established from time variation plots of working fluid properties.
Karthikeyan, K.,Anguraj, A. The Korean Society for Computational and Applied M 2012 Journal of applied mathematics & informatics Vol.30 No.1
In this paper, we prove the existence of mild solutions for a first order impulsive neutral differential inclusion with state dependent delay. We assume that the state-dependent delay part generates an analytic resolvent operator and transforms it into an integral equation. By using a fixed point theorem for condensing multi-valued maps, a main existence theorem is established.