Judul: Palm Ethnobotany in Beruas Village Community, Simpang Katis District, Central Bangka Regency
Abstrak: Aren (Arenga pinnata Merr.) merupakan spesies palma multiguna yang tersebar hampir di seluruh kawasan Indonesia, salah satunya di Desa Beruas. Penelitian ini bertujuan untuk mengidentifikasi profil masyarakat, bentuk pemanfaatan, kearifan lokal, dan tumbuhan berguna yang berada di sekitar tegakan aren. Pengambilan data dilakukan menggunakan metode wawancara secara mendalam, observasi partisipatif, dan dokumentasi. Hasil penelitian menunjukan bahwa seluruh petani aren di Desa Beruas berjenis kelamin laki-laki dengan dominan usia 36-45 tahun (dewasa akhir, KU III). Masyarakat memanfaatkan aren sebagai bahan pangan seperti gula aren dan kolang-kaling serta sebagai kerajinan tangan seperti sapu ijuk. Masyarakat memiliki kearifan lokal dalam menentukan aren yang menghasilkan banyak air melalui morfologi aren. Petani aren juga menggunakan pengawet alami seperti akar ube-ube kuning dan daun karamuang untuk memperpanjang masa simpan air nira. Spesies tumbuhan berguna yang pada umumnya ditemukan pada kelekak yaitu durian, nangka, manggis, cempedak, karet, dan kelapa., Sugar palm (Arenga pinnata Merr.) is a multipurpose palm species that is spread almost throughout Indonesia, one of which is in Beruas Village and Teru Village. This research aims to identify community profiles, forms of use, local wisdom, and useful plants located around sugar palm stands. Data collection was carried out using in-depth interview methods, participant observation, and documentation. The research results show that all sugar palm farmers in Beruas Village and Teru Village are male with a dominant age of 36-45 years (late adulthood, KU III). People use sugar palm as a food ingredient such as palm sugar and palm fruit and as a handicraft such as palm fiber brooms. The community has local wisdom in determining palm trees that produce a lot of water through palm morphology. Sugar palm farmers also use natural preservatives such as yellow ube- ube roots and Karamuang leaves to extend the shelf life of palm juice. Useful plant species that are generally found in kelekak are durian, jackfruit, mangosteen, cempedak, rubber, and coconut.
Keyword: aren, Kearifan lokal, kelekak, pemanfaatan aren

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: 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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