Judul: The Contribution of Tapping Pine Sap to the Welfare of the Community of Ronggur Nihuta Village Samosir Regency.
Abstrak: Getah pinus merupakan salah satu hasil hutan bukan kayu yang bernilai komersial dan potensial memiliki peluang dan nilai pasar yang tinggi. Hal ini membuat getah pinus dapat dimanfaatkan sebagai sumber pendapatan baru bagi masyarakat yang bertempat tinggal disekitar hutan, sehingga mampu berkontribusi terhadap pendapatan total rumah tangga dan berimplikasi terhadap kesejahteraan. Tujuan penelitian ini adalah menghitung kontribusi penyadapan getah pinus terhadap pendapatan rumah tangga masyarakat sekitar hutan dan menganalisis tingkat kesejahteraan rumah tangga penyadap getah pinus di Desa Ronggur Nihuta Kabupaten Samosir. Penelitian dilakukan menggunakan metode survey dengan pemilihan responden secara purposive berjumlah 49 orang. Data keadaan sosial dan ekonomi penyadap di lokasi penelitian dianalisis secara kualitatif dan kuantitatif. Hasil penelitian menunjukkan bahwa kontribusi hasil penyadapan getah pinus terhadap pendapatan rumah tangga penyadap tergolong besar yaitu 76,05%, akan tetapi berdasarkan kriteria kesejahteraan BPS, UMK Kabupaten Samosir, dan Bank Dunia sebagian besar keluarga penyadap getah pinus di Desa Ronggur Nihuta tergolong tidak sejahtera., Pine sap is a non-timber forest product that has commercial value and has the potential to have high market opportunities and value. This makes pine resin can be used as a new source of income for people who live around the forest, so that it can contribute to total household income and have implications for welfare. The purpose of this study was to calculate the contribution of tapping pine sap to household incomes of communities around the forest and to analyze the level of welfare of households tapping pine sap in Ronggur Nihuta Village, Samosir Regency. The study was conducted using a survey method with a purposive selection of respondents totaling 49 people. Data on the social and economic conditions of tappers at the research site were analyzed qualitatively and quantitatively. The results showed that the contribution of pine resin tapping to the household income of tappers was large, namely 76.05%, but based on the welfare criteria of BPS, UMK Samosir Regency, and the World Bank, most of the families of pine resin tappers in Ronggur Nihuta Village were classified as not prosperous.
Keyword: contribution, income, pine resin, tapper, welfare

Judul: Kontribusi Pendapatan Penyadap Getah Pinus Tehadap Kesejahteraan Penyadap Di BKPH Lengkong, KPH Sukabumi, Perum Perhutani Divisi Regional Jawa Barat-Banten
Abstrak: Pine resin is one of non wood forest product which utilized in Perum Perhutani and has high economic value. Perum Perhutani involves community surrounding forest area as pine resin tapper which aimed to increase of pine resin productivity and their community of welfare. This research aimed to obtain information regarding the level of welfare tappers, identify the characteristics of the tappers, and calculate the contribution of income from pine resin tapping on total tapper income of tappers. The research was conducted at BKPH Lengkong, KPH Sukabumi, Perum Perhutani Divisi Regional West Java-Banten with 78 respondents. The research result showed that the activity of pine sap contributed 67.15% of the total revenue tapper. According poverty line of Sajogyo, approximately 79.49% tappers are above the poverty line, according to the poverty line of World Bank, about 93.59% tappers are above the poverty line, whereas according to the Sukabumi UMR, approximately 64.10% tappers are not welfare.
Keyword: Bogor Agricultural University (IPB), Pine Resin, Tapper, Contribution, Involves community

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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