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: The Impact of Farmer Group Membership on Indonesia’s Chili Farming Income, The Impact of Farmer Group Membership on Indonesia’s Chili Farming Income
Abstrak: Cabai rawit merupakan salah satu komoditas strategis nasional, namun memiliki risiko harga yang tinggi dan produksinya fluktuatif. Sebagai akibatnya pendapatan petani cabai rawit juga bersifat fluktuatif. Kelompok tani menjadi salah satu upaya untuk menghadapi risiko tersebut. Mengingat kelompok tani berfungsi sebagai kelas belajar, wahana kerja, serta unit produksi bagi petani. Penelitian ini bertujuan untuk menganalisis dampak keanggotaan kelompok tani terhadap pendapatan usahatani cabai rawit. Data yang digunakan adalah data sekunder dari Survei Rumah Tangga Usaha Tanaman Hortikultura Tahun 2014 dengan jumlah 18.049 rumah tangga usahatani. Pengolahan data dilakukan secara kuantitatif, melalui metode deskriptif dan propensity score matching (PSM). Hasil penelitian menunjukkan bahwa penerimaan, biaya, dan pendapatan petani cabai rawit anggota kelompok tani lebih tinggi dibandingkan petani yang bukan anggota kelompok tani. Keanggotaan kelompok tani berpengaruh terhadap peningkatan biaya dan berpengaruh positif signifikan terhadap penerimaan dan pendapatan petani., Cayenne pepper, one of the national strategic commodities has fluctuating price and production risks. As a result, income of cayenne pepper farmers is also fluctuating. Farmer groups which function as learning classes, work platforms, and production units for farmers are few of many efforts to deal with the issue mentioned. This research aims to analyze the impact of farmer group membership on the cayenne pepper farming income. The data used is secondary data from Horticultural Crop Household Survey 2014 with total of 18.049 households. The data processing is carried out qualitatively and quantitatively. Qualitative data analysis using descriptive and quantitative methods using propensity score matching (PSM). Study results showed farmers who are farmer group members have higher incomes, costs, and revenues compared to farmers who are not farmer group members. Farmer groups membership impact on higher costs as well as significant positive effect towards farmer’s incomes and revenues.
Keyword: cayenne pepper, farmer group, farmer’s income, propensity score matching

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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