Judul: The Affecting Factors of Sugar Production in Indonesia due to National Sugar Self Sufficiency
Abstrak: Untuk memenuhi peningkatan konsumsi gula, pemerintah sedang gencar mendorong peningkatan produksi gula dengan target dapat berswasembada gula nasional. Akan tetapi, produktivitas gula saat ini tergolong rendah, dan produksi gula pun mengalami tren penurunan setiap tahunnya. Tujuan penelitian ini yaitu mendeskripsikan perkembangan agribisnis gula, menganalisis faktor-faktor yang memengaruhi produksi gula di Indonesia, dan meramalkan pencapaian swasembada gula Indonesia tahun 2025. Data yang digunakan berupa data runtun waktu dari tahun 1966-2019 dan dianalisis menggunakan metode VECM. Hasil analisis menunjukkan bahwa pada jangka pendek, produksi gula dipengaruhi oleh luas areal panen tebu dan konsumsi gula, sedangkan pada jangka panjang produksi gula dipengaruhi oleh konsumsi gula, impor gula, dan harga GKG. Peramalan hingga tahun 2025 menunjukkan bahwa ketergantungan Indonesia terhadap gula impor cenderung meningkat, sehingga Indonesia tidak dapat memenuhi target swasembada gula tahun 2025., In order to fulfill the increasing of sugar consumprtion, government is aggressively encouraging an increase in sugar production to achieve sugar selfsufficiency. However, the sugar production still has low productivity, and decreasing trend each year. This study aims to describe the growth of sugar agribusiness, analyze the affecting factors of sugar production, and forecast the achievement of sugar self-sufficiency in 2025. The data has been used in this study is time series data from 1966 until 2019, and analyzed by VECM method. The result of the analysis shows that, in the short term sugar production are affected by sugarcane harvest area and sugar consumption, while in long term, sugar production are affected by sugar consumption, sugar import, and price of paddy. Forecasting until 2025 shows that Indonesia's dependence on imported sugar tends to increase, so that Indonesia cannot achieve the sugar self-sufficiency target in 2025.
Keyword: production, self sufficiency, sugar, VECM

Judul: Analisis Faktor-faktor yang Memengaruhi Impor Gula di Indonesia
Abstrak: High sugar imports lead to import dependence that affects the domestic sugar industry. The purpose of this study is to analyze the development of the sugar industry conditions in Indonesia, measure the sugar import dependency ratio and factors that affect the import of sugar in the long run. This study uses the Vector Error Correction Model (VECM), and annual time series data from 1980 to 2012. The results of this study shows that sugar consumption increasing 3.82 percent per year while the production growth of ups and downs with 2.06 percent per year and imports continued to fluctuate with 6.86 percent per year during the period 1980-2012. Indonesian sugar import dependency ratio is still quite high with an average value of 26 percent per year. Based on VECM test, variables that significantly affect the sugar import are domestic production, domestic consumption, domestic sugar prices, international sugar prices, exchange rates and import tariffs on sugar. Meanwhile sugarcane planting area variable does not significantly affect the import of sugar in both the short and long term.
Keyword: VECM, import dependency ratio, sugar imports

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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