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: 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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