Judul: Peran Kelompok Tani terhadap Pendapatan Usahatani Bawang Putih di Tiga Sentra Produksi di Indonesia
Abstrak: Dalam upaya mewujudkan swasembada bawang putih, pemerintah telah melakukan upaya berupa pemberian input produksi dan pembentukan kelompok tani. Namun, petani cenderung melakukan usahatani secara individu sehingga program-program yang dibuat belum tersalurkan secara merata dan menyebabkan perbedaan biaya produksi dan pendapatan antara petani anggota dan bukan anggota kelompok tani. Oleh karena itu, penelitian ini bertujuan untuk menganalisis peran keanggotaan kelompok tani terhadap pendapatan usahatani bawang putih. Data yang digunakan adalah data sekunder dari Sensus Pertanian 2013 yaitu data Survei Rumah Tangga Usaha Tanaman Hortikultura tahun 2014. Pengolahan data dilakukan secara kualitatif dan kuantitatif. Analisis data kualitatif dengan metode deskriptif dan kuantitatif dengan analisis pendapatan serta Propensity Score Matching. Hasil penelitian menunjukkan bahwa kelompok tani belum mampu berperan positif terhadap pendapatan usahatani bawang putih. Rata-rata pendapatan, penerimaan, produktivitas, serta biaya total per tahun per hektar yang diperoleh petani anggota kelompok tani masih lebih rendah dibandingkan petani yang bukan anggota kelompok tani. Hal tersebut mengindikasikan bahwa fungsi kelompok tani belum berjalan sepenuhnya secara optimal., In order to be self-sufficient in garlic production, the government provides programs such as input subsidies and develop farmer groups. However, farmers tend to do farming individually so that assistance in efforts to be self-sufficient has not been distributed evenly, which will lead to differences in production costs and income between farmer members and non-members of farmer groups. Therefore, this study aims to analyze the impact of farmer group membership on garlic farm income. The data used is secondary data from the 2013 Agricultural Census, namely the 2014 Horticultural Plant Household Survey data. Data processing was carried out qualitatively and quantitatively. Qualitative data analysis with descriptive and quantitative methods with income analysis and Propensity Score Matching. The result shows that farmer group has not capable yet to increase garlic farming income. The average of total income, productivity level, as well as total cost per year per hectare obtained by farmers who are members of farmer groups is lesser than farmers who are not members of farmer group. Hence, it indicates that the function of farmer group is not running optimally yet as it should.
Keyword: farmer group, garlic, farm income, propensity score matching

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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