Judul: Estimating the Stand Biomass of  Community Forest at the Taman Wijaya Rasa Cooperative (Kostajasa) Kebumen  District Using the Tree Sampling
Abstrak: Metode tree sampling belum pernah digunakan untuk menduga biomassa tegakan hutan rakyat, sehingga jumlah pohon contoh yang efisien untuk metode tree sampling belum diketahui. Penelitian ini bertujuan untuk menentukan jumlah pohon contoh yang efisien untuk menduga biomassa tegakan, cadangan karbon, dan serapan CO2 pada hutan rakyat Kostajasa. Penelitian ini mengukur 3, 4, 5, 6, 7, 8, 9, 10, 11, dan 12 pohon contoh yang paling dekat dengan pusat plot contoh dari 81 unit contoh yang tersebar di lapangan dengan metode stratified sampling. Data yang diambil pada setiap unit contoh adalah jenis pohon, diameter pohon, tinggi pohon, dan jarak pohon terjauh. Hasil penelitian menunjukkan bahwa 12 pohon contoh dapat digunakan untuk menduga biomassa tegakan, menghasilkan rata-rata biomassa sebesar 83,41 ton/ha atau total biomassa 27632,88 ton dengan sampling error 14,08%. Nilai tersebut setara dengan cadangan karbon sebesar 39,20 ton/ha dengan total 12987,45 ton atau serapan CO2 sebesar 143,87 ton/ha dengan total 47663,95 ton., The tree sampling method has never been used to estimate stand biomass of community forests, so that an efficient number of sample tree for the tree sampling method is not known yet. The study aimed to determine an efficient number of sample tree for estimating the stand biomass, carbon stock, and CO2 sequestration of the Kostajasa’s community forests. This study measured 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 sample trees closest to the center of 81 sample units, which were established in the field using a stratified sampling method. The data collected in each sample unit were tree species, tree diameter, tree height, and distance to the farthest tree. The results showed that 12 sample trees could be used to estimate the stand biomass, resulting a mean biomass of 83,41 ton/ha or a total biomass of 27632,88 tons with a sampling error of 14,08%. These values equal to the carbon stock of 39,20 ton/ha or 12987,45 tons in total or the CO2 sequestration of 143,87 ton/ha or 47663,95 tons in total.
Keyword: biomass, community forest, tree sampling

Judul: Estimation of Biomass and CO2 Uptake of the Upper Stand of Community Forest Stands in Cimanggu Village, Cikembar District, Sukabumi Regency
Abstrak: Keberadaan hutan rakyat dapat dijadikan sebagai alternatif untuk meningkatkan serapan CO2 di atmosfer, melihat saat ini terjadi penurunan udara karena kurangnya sumber serapan alami. Tujuan penelitian ini adalah untuk mengetahui informasi mengenai besarnya dugaan biomassa, cadangan karbon, dan serapan CO2. Metode yang digunakan dalam pengambilan data pada setiap responden menggunakan sensus, sedangkan penentuan lokasi dan penentuan responden dipilih secara purposive sebanyak 36 responden berdasarkan luasannya di 4 dusun. Kandungan biomassa diduga menggunakan rumus persamaan allometrik dan metode konversi volume dengan menggunakan BEF. Hasil penelitian menunjukkan total dan rata-rata simpanan dugaan biomassa sebesar 179,22 ton dan 11,908 ton/ha. Total dan rata-rata stok karbon per satuan luas adalah 205,225 ton/ha dan 5,701 ton/ha, sedangkan dugaan serapan sebesar CO2 753,176 ton/ha dan 20,922 ton/ha. Dusun yang memiliki total dan rata-rata serapan CO2 terbesar adalah Dusun Cikembang sebanyak 333,723 ton/ha dan 37,08 ton/ha., The existence of community forests can be used as an alternative to increase CO2 absorption in the atmosphere, seeing that currently there is a decrease in air due to a lack of natural sources of absorption. The purpose of this study was to find out information about the magnitude of the estimated biomass, carbon stocks, and CO2 absorption. The method used in collecting data on each respondent was using a census, while determining the location and determining the respondents purposively selected as many as 36 respondents based on their area in 4 hamlets. Biomass content was estimated using the allometric equation formula and the volume conversion method using BEF. The results showed that the total and average estimated biomass savings were 179.22 tons and 11.908 tons/ha. The total and average carbon stocks per unit area are 205.225 tons/ha and 5.701 tons/ha, while the estimated CO2 absorption is 753.176 tons/ha and 20.922 tons/ha. The hamlets that have the largest total and average CO2 absorption are Cikembang Hamlet with 333.723 tons/ha and 37.08 tons/ha.
Keyword: biomass, carbon, community forest, CO2 absorption

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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