Judul: Structure of Costs and Income of  Cayenne Pepper Farming in Indonesian
Abstrak: Cabai rawit merupakan salah satu komoditas hortikultura dengan tingkat permintaan yang terus meningkat setiap tahunnya. Perbedaan wilayah, perbedaan dalam pengalokasian penggunaan input, dan perkembangan harga yang memengaruhi pendapatan usahatani cabai rawit. Penelitian ini bertujuan untuk menganalisis keragaan usahatani cabai rawit, struktur biaya, penerimaan hingga pendapatan usahatani cabai rawit. Data yang digunakan yaitu data sekunder yang bersumber Sensus Pertanian 2013: Survei Rumah Tangga Usaha Tanaman Hortikultura Tahun 2014. Jumlah sampel petani cabai rawit sebanyak 4818 petani responden. Metode analisis yang digunakan yaitu analisis struktur biaya, penerimaan, pendapatan, dan R/C ratio usahatani cabai rawit di kedua sentra cabai rawit. Hasil penelitian menunjukkan bahwa biaya tunai dan biaya total serta penerimaan total usahatani di Sumatra Utara lebih besar dibandingkan di Jawa Timur. Usahatani cabai rawit dikedua sentra menguntungkan dengan nilai pendapatan atas biaya tunai, pendapatan atas biaya total, dan nilai R/C ratio., Cayenne pepper is one of the garden crops whose demand is increasing year by year. Regional differences, differences in input use allocation, and price trends affecting income from cayenne pepper cultivation. This study aims to analyze the performance, cost structure, acceptance, and income of cayenne pepper cultivation. The data used is secondary data from the 2013 Agricultural Census: Horticultural Crops Household Survey 2014. The number of samples of cayenne pepper farmers was 4818 respondents. The analytical method used is the analysis of the cost structure, revenue, income, and R/C ratio of cayenne pepper farming in both centers of cayenne pepper. The results showed that the cash costs, total costs, and total income of farming in North Sumatra were greater than those in East Java. Cayenne pepper farming in both centers is profitable with the value of income on cash costs, income on total costs, and the value of the R/C ratio.
Keyword: cayenne pepper, cost structure, income, R/C Ratio

Judul: Red Chili Farming Income Based on Season in Central Java Province
Abstrak: Perbedaan musim memengaruhi struktur biaya dan penerimaan usahatani cabai merah di Provinsi Jawa Tengah. Oleh karena itu, penelitian ini bertujuan untuk menganalisis struktur biaya, penerimaan, dan pendapatan usahatani cabai merah pada musim kemarau dan musim hujan. Data yang digunakan yaitu data sekunder yang bersumber dari Sensus Pertanian 2013: Survei Rumah Tangga Usaha Tanaman Hortikultura Tahun 2014. Jumlah sampel petani cabai merah sebanyak 2535 petani. Metode analisis yang digunakan yaitu analisis struktur biaya, analisis penerimaan, analisis pendapatan, analisis R/C ratio, dan uji beda Mann-Whitney. Hasil penelitian menunjukkan biaya tunai dan biaya total usahatani cabai merah pada musim kemarau lebih besar daripada musim hujan. Begitu pula pada penerimaan tunai dan penerimaan total. Usahatani cabai merah pada musim kemarau lebih menguntungkan dengan nilai pendapatan atas biaya tunai, net farm income, R/C ratio, return to total capital, dan return to land yang lebih besar dibandingkan musim hujan. Hasil uji beda Mann-Whitney menunjukkan terdapat perbedaan yang signifikan terhadap variabel pendapatan dan R/C ratio usahatani cabai merah pada musim kemarau dan musim hujan.
Keyword: cost structure, income, R/C ratio, red chili, season

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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