Judul: Aren (Arenga pinnata Merr.) Potential and  Development in Cambai, South Cambai and Air Mesu Villages, Central Bangka  Regency
Abstrak: Aren (Arenga pinnata Merr.) merupakan salah satu spesies tumbuhan dari famili Arecaceae yang memiliki potensi nilai ekonomi dan ekologi yang tinggi. Penelitian bertujuan menduga potensi tegakan aren, menduga potensi produksi nira aren dan merencanakan pengembangan tegakan aren di Desa Cambai, Cambai Selatan dan Air Mesu. Penelitian dilakukan dengan metode analisis vegetasi. Pohon aren yang siap berproduksi memiliki kerapatan jarang, sedangkan aren yang belum siap berproduksi memiliki kerapatan padat. Kategori kelestarian di ketiga lokasi penelitian cukup lestari (fair) dengan pola sebaran mengelompok. Nilai pendugaan potensi tegakan di Desa Cambai, Cambai Selatan dan Air Mesu secara berturut-turut 50 (ind/desa), 279 (ind/desa) dan 25 (ind/desa). Produksi nira aren tertinggi yaitu terdapat pada Desa Cambai Selatan sebesar 2.759,31 liter/desa/hari. Desa Air Mesu dan Desa Cambai Selatan merupakan desa prioritas pengembangan aren karena memiliki luas habitat potensial yang tinggi., Aren (Arenga pinnata Merr.) is one of the plant species from the Arecaceae family that has high potential economic and ecological value. The research aims to estimate the potential of aren palm stands, estimate the potential production of aren palm sap and plan the development of aren palm stands in Cambai, South Cambai and Air Mesu villages. The research was conducted using vegetation analysis method. Palm trees that are ready to produce have a sparse density, while palm trees that are not ready to produce have a dense density. The sustainability category in the three research locations is quite sustainable (fair) with a cluster distribution pattern. The estimated potential value of stands in Cambai, South Cambai and Air Mesu villages are 50 (ind/village), 279 (ind/village) and 25 (ind/village) respectively. The highest production of palm sap was found in South Cambai Village at 2,759.31 liters/village/day. Air Mesu Village and South Cambai Village are priority villages for palm oil development because they have a high potential habitat area.
Keyword: aren, habitat potensial, potensi, produksi

Judul: Stand Potential  Aren (Arenga pinnata Merr.) in Beruas and Teru Villages, Central Bangka Regency
Abstrak: Aren merupakan tumbuhan palma dari famili Arecaceae yang memiliki banyak manfaat dan bernilai ekonomi bagi masyarakat Desa Beruas dan Teru. Pemanfaatan aren bergantung pada aren yang tumbuh liar sehingga tingkat produksi aren rendah. Tujuan penelitian untuk menduga potensi tegakan dan produksi nira aren dan menyusun rencana pengembangan aren. Pengambilan data dilakukan dengan studi literatur, analisis vegetasi, pengamatan lapang, dan wawancara. Data dianalisis secara deskripsi kualitatif dan kuantitatif meliputi pendugaan tegakan aren, pola sebaran, kategori kelestarian, produksi nira aren, dan rencana pengembangan tegakan aren. Penelitian menemukan bahwa Desa Beruas memiliki 252 pohon aren dengan klasifikasi kelestarian fair, sementara Desa Teru memiliki 116 pohon dengan kelestarian good. Pola persebarannya cenderung mengelompok. Rata-rata produksi nira aren di Desa Beruas mencapai 11,38 liter per pohon per hari, sementara di Desa Teru belum ada tegakan yang menghasilkan nira aren. Pengembangan agroforestri dapat dilakukan di Desa Beruas, tetapi tidak memungkinkan di Desa Teru karena kondisi tempat tumbuhnya tidak sesuai., Aren is a palm plant from the Arecaceae family that has many benefits and economic value for the people of Beruas and Teru villages. Aren utilization depends on wild-growing aren palm so that the level of aren palm production is low. The aim of the study was to estimate the potential of aren palm stands, the production of aren palm sap, and to compose the development plan of aren palm. Data were collected through literature study, vegetation analysis, field observation, and interview. Data were analyzed qualitatively and quantitatively including estimation of palm stands, distribution patterns, sustainability categories, palm juice production, and development plans for palm stands. The study found that Beruas village has 252 aren palm trees with fair sustainability classification, while Teru village has 116 trees with good sustainability. The distribution pattern tends to be clustered. The average production of palm sap in Beruas village reached 11.38 liters per tree per day, while in Teru village there were no stands producing palm sap. Agroforestry development is possible in Beruas village, but not in Teru village due to the unsuitable growing conditions.
Keyword: aren, nira, pola sebaran, potensi

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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