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: Factors Influencing Indonesia Red Chili Farmers Joining Farmers Group
Abstrak: Kelompok tani memiliki peran penting dalam pengembangan agribisnis cabai merah. Namun, hanya sebagian kecil petani cabai merah yang bergabung dengan kelompok tani. Penelitian ini bertujuan untuk menganalisis faktor-faktor yang memengaruhi petani cabai merah Indonesia bergabung dengan kelompok tani dan menganalisis perbedaan pendapatan usahatani cabai merah antara petani anggota dan non anggota kelompok tani. Data yang digunakan dalam penelitian ini adalah data sekunder Survei Rumah Tangga Usaha Tanaman Hortikultura Tahun 2014 oleh Badan Pusat Statistik (BPS) dengan jumlah sampel 19468 rumah tangga petani cabai merah. Data dianalisis dengan analisis regresi logistik biner dan uji beda Mann-Whitney. Hasil penelitian menunjukkan hanya sebesar 21,29% sampel petani cabai merah yang bergabung dengan kelompok tani. Faktor-faktor yang memengaruhi petani cabai merah bergabung dengan kelompok tani, yaitu jenis kelamin, usia, tingkat pendidikan, penggunaan teknologi produksi, penerimaan bantuan usahatani, keikutsertaan dalam penyuluhan, keanggotaan dalam KUD, dan kemitraan. Pendapatan usahatani cabai merah pada petani anggota kelompok tani lebih rendah dibandingkan petani non anggota., Farmers group has an important roles in the development of red chili agribusiness. However, only a small part of red chili farmers joining farmers group. This research aims to analyze factors influencing red chili farmers joining farmers group and to analyse the difference of red chili farming income between farmers group members and non members. Data used in this research were secondary data from Survei Rumah Tangga Usaha Tanaman Hortikultura Tahun 2014 by Badan Pusat Statistik (BPS) with total sample of 19468 red chili farmers households. Data were analysed by binary logistic regression analysis and Mann-Whitney difference test. The result showed that only 21,29% of red chili farmers sample joined farmers group. Factors influencing red chili farmers joining farmers group were gender, age, level of education, use of production technology, farming support acceptance, participation in extension, cooperative membership in KUD, and contract farming. Chili farmers members’ income was lower than non members’ farmers.
Keyword: farmers group, agribusiness institution, membership decision, farming income, red chili farming

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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