Judul: Income Analysis and Factors Affecting Pummelo Production in Pati District
Abstrak: Jeruk pamelo sebagai buah unggulan Kabupaten Pati memiliki produksi yang cenderung meningkat sementara luas lahan panen cenderung menurun. Artinya ada faktor lain yang memengaruhi produksi selain luas lahan. Namun, produksi tinggi belum tentu mencerminkan pendapatan petani juga tinggi. Penelitian ini dilakukan untuk menganalisis faktor-faktor yang memengaruhi produksi dan menganalisis pendapatan petani jeruk pamelo di Kabupaten Pati. Metode analisis yang digunakan yaitu analisis deskriptif, analisis fungsi produksi Cobb-Douglass, serta analisis pendapatan usahatani dan R/C ratio. Hasil regresi menunjukkan bahwa hanya 2 dari 6 faktor yang berpengaruh nyata. Faktor jumlah pohon dan penggunaan tenaga kerja berpengaruh positif signifikan terhadap produksi. Hasil analisis pendapatan usahatani menunjukkan bahwa usahatani tidak menguntungkan jika memperhitungkan seluruh biaya (total biaya) dan tidak mampu memberikan imbalan terhadap seluruh sumber daya yang digunakan. Kerugian bersih yang diterima petani sebesar Rp 132.967,00 per pohon per tahun dengan R/C atas total biaya sebesar 0,8918. Namun, jika hanya memperhitungkan biaya tunai, usahatani masih memberikan keuntungan Rp 297.194,00 per pohon per tahun dengan R/C sebesar 2,3297., Pummelo as a superior fruit in Pati Regency has a production that trends to increase while the area of harvested land trends to decrease. It mean that there are other factors that influence production besides land area. However, high production does not necessarily reflect high farmers income. This research was conducted to analyze the factors that influence production and to analyze the income of pummelo farmers in Pati Regency. The analytical method used is descriptive analysis, Cobb-Douglass production function analysis, and farm income analysis and R/C ratio. The regression results show that only 2 of 6 factors have a real effect. The number of trees and the use of labor had a significant positive effect on production. The results of the analysis of farm income show that farming is not profitable if it takes into account all costs (total costs) and it unable to provide rewards for all the resources used. The net loss received by farmers was IDR 132.967,00 per tree per year and R/C for the total cost of 0,8918. However, if only consider cash costs, farming still provides a profit of IDR 297.194,00 per tree per year and R/C of 2,3297.
Keyword: income, production, production factor, R/C ratio

Judul: Analysis of Youth Interest in Working as Farmers of Pamelo Oranges (Citrus maxima) in Tambakmas Village, Sukomoro Subdistrict, Magetan Regency
Abstrak: Desa Tambakmas merupakan desa sentra jeruk pamelo yang sebagian besar penduduknya bekerja sebagai petani jeruk pamelo. Petani jeruk pamelo didominasi berumur tua. Rendahnya minat pemuda terhadap pekerjaan sebagai petani jeruk pamelo dapat menghambat regenerasi petani dan keberlanjutan usahatani tersebut. Penelitian ini bertujuan untuk (1)menganalisis pendapatan usahatani jeruk pamelo di Desa Tambakmas, (2)menganalisis persepsi pemuda Desa Tambakmas terhadap pekerjaan sebagai petani jeruk pamelo, (3)menganalisis faktor-faktor sosial ekonomi yang memengaruhi minat pemuda Desa Tambakmas terhadap pekerjaan sebagai petani jeruk pamelo. Metode analisis data terdiri dari analisis pendapatan, skala likert, dan regresi logistik biner. Hasil analisis menunjukkan R/C ratio lebih dari satu dan rata-rata pendapatan usahatani jeruk pamelo menguntungkan, tetapi lebih rendah daripada UMK Kabupaten Magetan tahun 2021 dan 2022. Persepsi pemuda Desa Tambakmas setuju terhadap pekerjaan sebagai petani jeruk pamelo yang memiliki pendapatan positif, lingkungan kerja nyaman, membuka lapangan pekerjaan, meningkatkan status sosial, tidak merusak lingkungan, tetapi terdapat risiko dalam pengelolaannya. Faktor-faktor sosial ekonomi yang berpengaruh signifikan pada taraf nyata lima persen adalah jenis kelamin, status pernikahan, lama pendidikan, pendapatan orang tua, latar belakang pekerjaan orang tua pemuda, dan persepsi pemuda terhadap pekerjaan sebagai petani jeruk pamelo. Berdasarkan hal tersebut, diperlukan pelatihan dan manajemen risiko budidaya jeruk pamelo untuk meningkatkan minat pemuda., Tambakmas village is one of the pamelo oranges village where most of the residents work as pamelo orange farmers. Pamelo orange farmers in this village are dominated by old farmers. Some youths are not interested in working as pamelo orange farmers which constrains the regeneration and sustainability of pamelo oranges farming. This study aims to (1) analyze the income of pamelo orange farmers in Tambakmas village, (2) analyze the perception of the youth of Tambakmas village towards work as a pamelo orange farmers, (3) analyze of socio-economic factors that influence the interest of the youth of Tambakmas village towards work as a pamelo orange farmers. Data analysis methods are income analysis, likert scale, and binary logistic regression. The result of the analysis show that the R/C ratio is more than one and income average of pamelo orange farming is profitable, but lower than the UMK in Magetan Regency in 2021 and 2022.The youth of Tambakmas village have the perception of agreeing to work as a pamelo orange farmers, which is indicated by a positive value income, a comfortable work environment, creating jobs, increasing of social status, and not damaging the environment, but there are risks in its management. The factors of socio-economic that have a significant level of five percent are gender, marital status, length of education, parents income, the work background of the youth’s parents and the youth’s perception of work as a pamelo orange farmers. Based on this, training and risk management of pamelo oranges cultivation are needed to increase youth interest.
Keyword: binary logistics regression, farmer regeneration, income analysis, likert scale, youth perception

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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