Judul: Faktor-faktor yang mempengaruhi produksi manggis di Desa Karacak dan Desa Barengkok Kecamatan Leuwiliang Kabupaten Bogor
Abstrak: Bogor district is known as a central of developing of mangosteen commodity in Indonesia. This is supported not only by potential of agricultural in Bogor district but also the condition of agroecosistem which is very good for mangosteen commodity. Karacak and Barengkok villages in Leuwiliang sub-district are known as a central of mangosteen. The number of crops in this villages have fluctuating in every year cause of some factor, such as the width of area to plant on, the age of mangosteen tree and human resources. Based on these, the goal of research is (1) to identify the that can be influence the mangosteen crops in Karacak and Barengkok villages as sub district of Leuwiliang, Bogor district and (2) to compare the mangosteen crops in these two villages
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Judul: Factors Affecting Production and Income of Mangosteen  Farming in Kaligesing District, Purworejo Regency
Abstrak: Produksi manggis di Kabupaten Purworejo mengalami perubahan jumlah produksi akibat dari pengaruh penggunaan input yang kurang optimal serta umur pohon yang tua khususnya di Kecamatan Kaligesing sebagai sentra produsen buah manggis. Selain itu, harga jual yang rendah diikuti dengan jumlah produksi yang sedikit serta biaya produksi yang tinggi menyebabkan pendapatan menjadi rendah. Tujuan dari penelitian ini adalah untuk menganalisis faktor – faktor yang memengaruhi produksi dan pendapatan usahatani manggis di Kecamatan Kaligesing. Penelitian ini dilaksanakan di Desa Somongari dan Kaligono. Jenis data yang digunakan dalam penelitian ini berupa data kuantitatif dan kualitatif yang bersumber dari data primer dan sekunder. Jumlah sampel sebanyak 60 responden dengan teknik simple random sampling. Metode analisis data menggunakan analisis deskriptif dan analisis regresi linear berganda. Usahatani manggis di Kecamatan Kaligesing menguntungkan untuk dijalankan berdasarkan nilai R/C yang dihasilkan. Hasil regresi menunjukkan variabel luas lahan berpengaruh signifikan terhadap produksi manggis serta variabel harga jual, biaya pupuk kendang, dan biaya pupuk NPK berpengaruh signifikan terhadap pendapatan petani manggis., Mangosteen production in Purworejo Regency experienced changes in the amount of production as a result of the influence of the use of inputs that were less than optimal and the age of old trees, especially in Kaligesing District as a center for mangosteen fruit producers. In addition, the low selling price followed by the small amount of production and high production costs causes low income. The purpose of this research is to analyze the factors that influence the production and income of mangosteen farming in Kaligesing District. This research was carried out in the Villages of Somongari and Kaligono. The type of data used in this study is in the form of quantitative and qualitative data originating from primary and secondary data. The number of samples is 60 respondents with simple random sampling technique. Methods of data analysis using descriptive analysis and multiple linear regression analysis. Mangosteen farming in Kaligesing District is profitable to run based on the resulting R/C value. The regression results show that the variable land area has a significant effect on mangosteen production and the variable selling price, the cost of manure, and the cost of NPK fertilizer have a significant effect on the income of mangosteen farmers.
Keyword: farming, income, mangosteen, production

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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