Judul: Analisis Kelayakan Pendirian Unit Biogas Kotoran Domba pada Kelompok Ternak Teguh Mandiri Desa Nagrak Bogor
Abstrak: Increased livestock followed also increased by the livestock waste. Biogas fecal waste treatment plant is a right alternative to solves livestock waste problems. The purpose of this research is to analyze the feasibility of Kelompok Ternak Teguh Mandiri in planning the establishment of biogas processing unit sheep waste. The analysis includes financial and non-financial aspects and also the sensitivity of strengthness biogas treatment unit. The results of the study concluded non-financial feasibility has been fullfilled. Financial aspect feasibility are shown by NPV Rp.209.416.798, Net B/C 2,31, IRR 26.41% and Payback periode 4,303 years. Sensitivity test shown that biogas plant unit ability of decreasing rate of input unit is 29,447517%, decreasimg rate of wholesale price is 25,9038328% and increasing rate of variable cost as 215,257202%
Keyword: Establishment of Biogas Processing, Feasible

Judul: Feasibility of Sheep and Biogas Farming (Case Study: Cikarawang Farm)
Abstrak: Jawa Barat merupakan provinsi dengan jumlah peternakan domba terbesar di Indonesia, yaitu 9.987.870 ekor domba pada tahun 2022. Hal tersebut menimbulkan permasalahan lingkungan salah satunya adalah limbah feses atau kotoran domba yang belum dimanfaatkan. Penelitian ini berfokus pada kelayakan usaha peternakan domba dan penerapan biogas di Cikarawang Farm, Bogor. Penelitian ini bertujuan untuk menganalisis kelayakan finansial dan non-finansial dari penggunaan teknologi biogas dalam peternakan domba, serta melakukan analisis switching value. Data dikumpulkan dari 32 responden menggunakan kuesioner dan wawancara. Data dianalisis dengan kriteria investasi seperti NPV, IRR, Net B/C dan PP. Tanpa biogas, NPV sebesar Rp466.418.189, IRR mencapai 22%, Net B/ sebesar 1.04 dan PP selama 4.5 tahun. Sementara itu, dengan penerapan biogas, Rp578.762.730 , IRR naik menjadi 28%, Net B/C juga meningkat menjadi 1.34 dan Payback Period berkurang menjadi 4.1 tahun. Analisis switching value mengindikasikan bahwa penurunan harga domba dapat berdampak negatif pada pendapatan. Kesimpulannya, penggunaan teknologi biogas layak secara finansial dan non-finansial, meskipun terdapat tantangan yang perlu diatasi untuk memaksimalkan keuntungan dan keberlanjutan usaha., West Java is the province with the largest number of sheep farms in Indonesia, totaling 9,987,870 sheep in 2022. This creates environmental issues, particularly with untreated sheep manure. This study focuses on the feasibility of sheep farming and biogas application at Cikarawang Farm, Bogor, aiming to analyze the financial and non-financial aspects of biogas technology, as well as conduct a switching value analysis. Data were collected from 32 respondents through questionnaires and interviews, and analyzed using investment criteria such as NPV, IRR, Net B/C, and Payback Period (PP). Without biogas, NPV was Rp466.418.189, IRR was 22%, Net B/C was 1.04, and PP was 4.5 years. With biogas, NPV rose to Rp578.762.730, IRR increased to 28%, Net B/C rose to 1.34, and Payback Period extended to 4.1 years. The switching value analysis indicates that a decrease in sheep price can negatively impact income. In conclusion, biogas technology is financially and non-financially feasible, though challenges remain to maximize profits and business sustainability.
Keyword: biogas, domba, non finansial, Switching Value, aspek finansial

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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