Gunawan Nugroho

Duelist Algorithm: An Algorithm Inspired by How Duelist Improve Their Capabilities in a Duel

This paper proposes an optimization algorithm based on human fight and learn from each duelist. The proposed algorithm starts with an initial set of duelists. The duel is to determine the winner and loser. The loser learns from the winner, while the winner try their new skill or technique that may improve their fighting capabilities. A few duelists with highest fighting capabilities are called as champion. The champion train a new duelist such as their capabilities. The new duelist will join the tournament as a representative of each champion. All duelist are re-evaluated, and the duelists with worst fighting capabilities is eliminated to maintain the amount of duelists. Several benchmark functions is used in this work. The results shows that Duelist Algorithm outperform other algorithms in several functions.

Electrochemical analysis of electrolyte additive effect on ionic diffusion for high-performance lithium ion battery

Lithium ion batteries have gained increasing attention in the last two decades. Perfoming electrolyte additive into lithium ion battery could enhance the baterry performance. However several studies on electrolyte additive only show the experimental data. The behavior of battery kinetic inside the battery and the ionic diffusion during operation was not analyzed. This study will investigate the effect of electrolyte additive on ionic diffusion of battery based on electrochemical model. The role of the electrolyte is to provide an ionic conduction path between the anode and the cathode. This study elucidates the improvement of the cycleability by performing the electrolyte containing 0.1 wt % of Flouro-o-phenylenedimaleimide (F-MI) based additive compared to the electrolyte with 0.1 wt % N,N’-o-phenylenedimaleimide (O-MI) and without an additive shown by effective constant phase elements (CPE) coefficient of impedance spectra on electrochemical impedance spectroscopy (EIS). The result elucidates that many amount of lithium ion remains on SEI layer of the mesocarbon microbeads (MCMB) half cell with F-MI additive, indicating that ion move easily because of high diffusion. The simulation result elucidated the agreement with the experimental data, the diffusion of the MCMB half-cell with F-MI additive is highest compared to MCMB half-cell with O-MI and without additive, that is emphasized with result on the EIS test.

Toward Reduction of Conservation Equations in Curvilinear Coordinate Systems into a Set of ODEs Using the Method of Characteristics

This work examined the conservation equations in curvilinear coordinates using the method of characteristics. The method is commonly applied to solve first-order partial differential equations. When applying this method to the conservation laws, the main difficulty is mass and momentum equations which are simultaneous and nonlinear PDEs. The method utilizes the separation of order in order to solve the problem. The resulting nonlinear ODEs in the main equation and characteristic variables were performed by the implementation of the system of Riccati and polynomial equation. The system of polynomial and Riccati equation is handled by the proposed method to solve each polynomial and Riccati equation. Both results were then equated to define each ODE solution. The procedure was then repeated sequentially to reach the final solutions for velocities, pressure, and temperature.

Toward the analytical model of SEI formation and development in lithium-ion battery: The case of solution of the nonlinear transport equation

The nonlinear lithium-ion transport equation with variable diffusion coefficient is considered in this research. The solution is produced by transforming the second order spatial variable into the first order differential in, ξ. The method of characteristics is then implemented for covering the initial-boundary conditions. Several interesting results are obtaining after the calculating the generated solution. It is found that dendrite formation is detected after 100 s which is considered as steady operation. In this case, the concentration ratio is smaller than boundary value at the top surface and the ratio of tip and surface current is high. Also the development of dendrite length is investigated to support the insight from the analytical model.

Performance of Seawater Activated Battery as Alternative Energy Resources

 Research on Freshwater and Seawater batteries, which using Al and Cu electrodes at variation of different electrolyte salinity, distance between electrodes and flowrate of electrolyte has been carried out. The galvanostatic discharge and Electrochemical Impedance Spectroscopy (EIS) of Al and Cu in seawater were investigated. The results showed the optimum condition with significant average potential discharge of 45,02 mV and current of 0,440 mA obtained from combination of 5% electrolyte salinity, 2 cm space between electrodes and 0,5 liter/hour electrolyte rate. EIS studies revealed that the Al and Cu interficial electrochemical process in seawater was determined by an activation controlled reaction. Keywords Seawater Battery, Galvanostatic Discharge, Electrochemical Impedance Spectroscopy.

CFD Studies on the Flanged Diffuser Augmented Wind Turbine with Optimized Curvature Wall

The Diffuser Augmented Wind Turbine (DAWT) offers potentials to cope with the wind availability situation like in Indonesia, i.e. with yearly average of 3–5 m/s. In this paper, computational CFD studies to get insight into the role of adding a flange (at the trailing edge of previously proposed diffuser with interior wall model [1]) to the wind velocity intensification inside the diffuser. Two models of flange are investigated, i.e. the flat-flange and airfoil-shaped flange. The role of angle-of-installment that provides the maximum velocity inside the diffuser is also reported. Results show that the additional flange to the trailing-edge of the diffuser will more step up the air velocity inside the diffuser. The installment of flat-flange will additionally increase the air velocity up to 29% higher. Meanwhile by optimizing the position of flange’s angle, a more step up in velocity up to 3% can still be harvested (i.e. max at ϕ = 60°). An even higher additional velocity (in compare to the installment of flat-flange) can be harvested by installment of flange with airfoil-shape, i.e. up to 31% (max at ϕ = 72°).