Judul: Ethnobotany of Aren Palm in the community of Cambai Village, South Cambai Village and Air Mesu Village, Central Bangka District
Abstrak: Aren atau kabung merupakan salah satu spesies tumbuhan palma yang memiliki potensi nilai ekologi, ekonomi, maupun sosial yang ditemukan di Desa Cambai, Cambai Selatan, dan Air Mesu. Penelitian bertujuan untuk mengidentifikasi profil masyarakat, bentuk pemanfaatan, kearifan lokal, dan tumbuhan berguna yang ada di sekitar tegakan aren di Desa Cambai, Cambai Selatan, dan Air Mesu. Pengambilan data dilakukan menggunakan metode wawancara, observasi partisipatif, dan dokumentasi. Hasil penelitian menunjukkan bahwa petani aren didominasi kelompok umur dewasa akhir dan semuanya berjenis kelamin laki-laki. Masyarakat memanfaatkan aren untuk diolah sebagai gula aren, bahan makanan dan minuman, obat-obatan, kayu bakar, perabot rumah tangga, serta media tanam. Masyarakat memanfaatkan olahan gula aren untuk digunakan sebagai bahan dalam pembuatan makanan tradisional. Petani aren memiliki kearifan lokal untuk menentukan aren yang menghasilkan banyak air dengan melihat sifat fisik aren. Petani aren juga menggunakan akar ube-ube, daun manggis, kapur sirih, dan teras cempedak sebagai pengawet air nira. Aren tumbuh di kebun campuran milik warga yang disebut sebagai kelekak. Spesies tumbuhan berguna yang biasanya terdapat pada kelekak yaitu manggis, nangka, cempedak, dan durian., Sugar palm or kabung is a species of palm plant that has potential ecological, economic and social value which is found in the villages of Cambai, South Cambai and Air Mesu. The research aims to identify community profiles, forms of use, local wisdom and useful plants around sugar palm stands in the villages of Cambai, South Cambai and Air Mesu. Data collection was carried out using interview methods, participant observation and documentation. The results of the research show that sugar palm farmers are dominated by the late adult age group and all of them are male. People use sugar palm to process it as palm sugar, food and drink ingredients, medicines, firewood, household furniture and planting media. People use processed palm sugar to use it as an ingredient in making traditional food. Palm farmers have local wisdom to determine which palm produces a lot of water by looking at the physical properties of palm. Sugar palm farmers also use ube-ube roots, mangosteen leaves, whiting, and cempedak terraces as sap water preservatives. Sugar palm grows in mixed gardens owned by residents called kelekak. Useful plant species that are usually found in kelekak are mangosteen, jackfruit, cempedak, and durian.
Keyword: local wisdom, useful plants, use of sugar palm

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: 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.
Keyword: