Judul: Greenhouse Gas Emissions from Beef Cattle  Manure in Semangke Hamlet, Jenu District, Tuban Regency
Abstrak: Emisi gas rumah kaca (GRK) merupakan salah satu penyebab utama perubahan iklim. Peternakan, dengan kontribusi besar terhadap emisi GRK seperti CO2, CH4 dan N2O, turut berperan dalam masalah ini. Penelitian ini fokus pada emisi metana (CH4) yang dihasilkan oleh peternakan sapi potong di Dusun Semangke, Kecamatan Jenu. Menggunakan metode IPCC AFOLU Tier-2, total populasi ternak sebanyak 32,05 satuan ternak di Dusun Semangke diperkirakan dapat menghasilkan emisi GRK sebesar 23,00 Gg CO2-e tahun-1 . Emisi tersebut terdiri dari tiga komponen utama: fermentasi methan fermentasi entirik sebesar 22,31 Gg CO2-e tahun-1 , emisi methane dari pengelolaan ternak sebesar 0,67 Gg CO2-e tahun-1 , dan emisi N2O dari pengelolaan kotoran sebesar 0,02 Gg CO2-e tahun-1 , Meskipun demikian, sektor pertanian di Dusun Semangke memiliki kapasitas penyerapan karbon sebesar 1239,50 Gg CO2-e tahun-1 , yang melebihi emisi yang dihasilkan dari populasi ternaknya. Bersasarkan surplus serapan karbon sebesar 1216,50 Gg CO2-e tahun-1 , dapat disimpulkan bahwa kondisi ini bisa terus ditingkatkan melalui program mitigasi seperti manajemen pakan, pengelolaan kotoran dan penanaman hijauan pakan., Greenhouse gas (GHG) emissions are one of the main drivers of climate change. With significant contributions to GHG emissions such as CO2, CH4, and N2O, livestock play a role in this issue. This study focused on methane (CH4) emissions from beef cattle farming in Semangke Hamlet, Jenu Sub-district. Using the IPCC AFOLU Tier-2 method, the total livestock population of 32,05 livestock units in Semangke Hamlet emitted 23,00 Gg CO2-e year-1 of GHGs. These emissions consisted of three main components: enteric fermentation methane emissions of 22,31 Gg CO2-e year-1 , methane emissions from livestock management of 0,67 Gg CO2-e year-1 , and N2O emissions from manure management of 0,02 Gg CO2-e year-1 . Despite this, the agricultural sector in Semangke Hamlet has a carbon sequestration capacity of 1239,50 Gg CO2-e year-1 , which exceeds the emissions generated by its livestock population. With a carbon sequestration surplus of 1216,50 Gg CO2-e year-1 , it can be concluded that this condition can be further improved through mitigation programs such as feed management, manure management, and forage planting.
Keyword: beef cattle, IPCC, greenhouse gas, Tier 2

Judul: Methane Gas Flux Analysis from Biogas Sheep Manure and Combination of Sheep and Beef Cattle Manure
Abstrak: Sektor Peternakan berkontribusi sebagai penyumbang emisi gas rumah kaca (GRK) seperti metana (CH4), karbon dioksida (CO2), dan dinitrogen oksida (N2O). Tujuan penelitian adalah menganalisis fluk gas CH4 dari biogas kotoran domba dan kombinasi kotoran domba serta sapi potong. Perlakuan meliputi 100% kotoran domba (T1) dan kombinasi 15% kotoran domba serta 85% kotoran sapi potong (T2) dengan dua ulangan untuk setiap perlakuan. Analisis TS, VS, C, N, dan C/N rasio setiap perlakuan diperoleh dari kotoran ternak dan substrat biogas pada awal pengamatan setiap perlakuan. Pengukuran fluk CH4 dan CO2 dilakukan setelah sepuluh hari memasukkan substrat ke dalam digester dengan interval tiga hari sekali selama empat kali pengukuran. Hasil penelitian menunjukkan bahwa nilai TS pada perlakuan T1 dan T2 berbeda secara signifikan (p<0,05). Nilai pH rata-rata pada perlakuan T1 adalah 6,7 dan pada perlakuan T2 adalah 6,6. Nilai rata-rata fluk gas CH4 T1 adalah 40 mgCH4/m2/day dan 107,13 mgCH4/m2/day pada T2 dan kedua perlakuan menunjukkan perbedaan secara signifikan (p<0,05). Komposisi substrat sangat menentukan kandungan TS dan nilai pH dalam fermentasi anaerob produksi biogas., The livestock sector contributes to greenhouse gas (GHG) emissions such as methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O). The study aimed to analyze CH4 flux from the biogas of sheep manure and the combination of sheep and beef cattle manure. The treatments included 100% sheep manure (T1) and a combination of 15% sheep manure and 85% beef cattle manure (T2) with two replications for each treatment. Analysis of TS, VS, C, N, and C/N ratio was obtained from livestock manure and biogas substrate at the beginning of the observation. Measurements of flux CH4 and CO2 were made after ten days of feeding the substrate into the digester at intervals of once every three days for four observations results showed that the T1 and T2 treatment TS values were significantly different (p<0.05). The average pH value in the T1 treatment was 6,7 and the T2 treatment was 6.6. The mean value of CH4 T1 flux was 40 mgCH4/m2/day and 107.13 mgCH4/m2/day in T2 and both treatments differed significant (p<0.05). The composition of the substrate largely determines the TS content and pH value in the anaerobic fermentation of biogas production.
Keyword: biogas, gas rumah kaca, kotoran domba, kotoran sapi potong, beef cattle manure, biogas, greenhouse gases, sheep manure

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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