Judul: Completion of the Lotka Volterra Model of Two Species Using the Homotopy Analysis Method
Abstrak: Dalam tulisan ini, model Lotka Volterra dua spesies yang bersaing dan dikembangkan oleh Bakare et.al (2018) diselesaikan dengan metode analisis homotopi. Dalam metode ini didefinisikan suatu persamaan deformasi dengan memperkenalkan suatu operator linear. Tujuan penelitian ini adalah menentukan penyelesaian semi-analitik dari model Lotka Volterra dengan menggunakan persamaan deformasi yang didefinisikan. Hampiran penyelesaian yang diperoleh ini cukup baik untuk mendekati penyelesaian model Lotka Volterra dua spesies. Beberapa tafsiran terhadap penyelesaian dari model untuk perubahan tingkat intrinsik spesies satu dan spesies dua, juga diberikan. Hasil simulasi menunjukkan bahwa penyelesaian tingkat intrinsik populasi spesies satu menghasilkan penurunan pada jumlah spesies kedua. Kata kunci: metode analisis homotopi, model Lotka Volterra, semi-analitik, In this paper, the competing two species Lotka Volterra model developed by Bakare et.al (2018) was completed using the homotopy analysis method. In this method a deformation equation is defined by introducing a linear operator. The purpose of this study was to determine the semi-analytic solution of the Lotka Volterra model using the defined deformation equation. The approximation of the obtained solution is good enough to approximate the completion of the two species Lotka Volterra model. Several interpretations of the completion of the model for changes in the intrinsic rate of species one and species two, are also given. The simulation results show that the completion of the intrinsic level of the population of one species results in a decreacse in the number of the second species. Keywords: homotopy analysis method, model Lotka Volterra, semi-analytic.
Keyword: metode analisis homotopi, model Lotka Volterra, semi-analitik

Judul: Penggunaan Metode Homotopi Pade' untuk Menyelesaikan Masalah Lotka–Volterra Logistik.
Abstrak: In this research, the problems of Lotka–Volterra and Lotka–Volterra with prey logistic growth models are solved by using homotopy and Pade' homotopy methods. The homotopy method is an analytical approach to solve non linear problems. The solution of homotopy method is common series. The solution of the problem using Pade' homotopy method is obtained by using the result of applying the homotopy method and then transforming the equation into the form of rational function. The results of homotopy and Pade' homotopy methods are compared with some numerical solutions. The result shows that in solving Lotka–Volterra and Lotka–Volterra with prey logistic growth, the Pade' homotopy method is better than homotopy method because the Pade' homotopy method covers a larger area of convergence and produces smaller errors.
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Judul: Elektrodeposisi Film Tipis Semikonduktor Cu2ZnSnS4 (CZTS) pada Substrat Kaca ITO
Abstrak: Semiconductor Cu2ZnSnS4 (CZTS) thin film that can be used as absorber layers on solar cell module was made via electrodeposition method. CZTS thin film was electrodeposited on the surface of a silicate glass coated with a thin layer of indium tin oxide (ITO). Deposition process was done using potentiostatic mode at room temperature with a potential of 1.05 V for 30, 45, and 60 minutes, followed with annealing the film at 2 different temperatures, 500 ºC using furnace and 180 ºC using hot plate, both treatments for 45 minutes in N2/H2S atmosphere. The X-ray difractograms were analyzed using Match 2 program and showed that the CZTS thin films had kesterit crystalline structure, with a low percentage of CZTS phase. The thin film also contained secondary phases such as Cu2S, ZnS, and SnS. The obtained CZTS thin films had a thickness between 1.039 and 1.676 μm. Absorption study showed that the band gap energy of CZTS thin films which was annealed using furnace ranged from 1.50 to 1.52 eV, whereas that annealed using the hot plate was not observed. The band gap energy value showed that CZTS thin films can be used as sunlight absorber layers on solar cell. The formation of CZTS crystal film on this investigation was effectively performed using furnace annealing process at a temperature of 500 ºC with deposition time of 45 minutes.
Keyword: Thin film, Electrodeposition, Cu2ZnSnS4