Judul: Analysis of Potential Non-Timber Forest Products in North Sumatra
Abstrak: Sumatera Utara memiliki potensi Hasil Hutan Bukan Kayu yang besar karena memiliki kawasan hutan yang luas. Komoditas HHBK di Sumatera Utara masih belum dimanfaatkan secara optimal. Tujuan penelitian ini mengetahui jenis HHBK yang berpotensi di Sumatera Utara. Jenis-jenis HHBK yang tercatat di Dinas Kehutanan Provinsi Sumatera Utara yaitu getah pinus, rotan manau, daun nilam, biji rotan, cengkeh, daun cengkeh, rotan sega (taman), rotan semambu, madu, dan nira. Data dan informasi diperoleh melalui hasil data sekunder yang berasal dari Dinas Kehutanan Sumatera Utara, situs internet resmi Badan Pusat Statistik Sumatera Utara, jurnal serta buku pustaka yang mendukung. Hasil penelitian menunjukkan jenis HHBK yang paling berpotensi pada saat ini di Sumatera Utara adalah getah pinus karena getah pinus memiliki Provisi Sumber Daya Hutan (PSDH) yang meningkat setiap tahunnya. PSDH yang dihasilkan getah pinus di Sumatera Utara dapat menambah pemasukan pendapatan Provinsi Sumatera Utara dan didukung oleh tempat tumbuh yang sesuai untuk pertumbuhan pinus berdasarkan kondisi iklim dan edafis., North Sumatra has great potential for non-timber forest products (NTFP) because it has a large forest area. NTFP commodities in North Sumatra are still not used optimally. The purpose of this study was to determine the types of NTFPs that have the potential in North Sumatra. The types of NTFPs recorded at the North Sumatra Provincial Forestry Service are pine resin, manau rattan, patchouli leaves, rattan seeds, cloves, clove leaves, sega (taman) rattan, semambu rattan, honey, and nira. Data and information were obtained through secondary data from the North Sumatra Forestry Service, the official website of the Central Statistics Agency of North Sumatra, journals and books that support. The results showed that currently the most potential NTFP species in North Sumatra is pine resin because pine resin has a Forest Resource Provision (FRP) which increases every year. FRP produced by pine resin in North Sumatra can increase the income of the Province of North Sumatra and is supported by suitable growing places for pine growth based on climatic and edaphic conditions.
Keyword: NTFPs, pine resin, FRP, potential

Judul: Pendugaan Nilai Pemanfaatan Hasil Hutan Bukan Kayu di Desa Simatalu Zona Tradisional Taman Nasional Siberut
Abstrak: Masyarakat sekitar hutan sangat bergantung pada hasil hutan untuk memenuhi kebutuhan hidup mereka. Salah satu jenis hasil hutan yang dimanfaatkan masyarakat adalah hasil hutan bukan kayu (HHBK). Pemanfaatan HHBK merupakan serangkaian kegiatan yang mencakup pemanenan, pengolahan, serta pemasaran komoditas hasil hutan tersebut. Penelitian ini bertujuan untuk mengidentifikasi bentuk pemanfaatan dan menduga nilai ekonomi berbagai spesies HHBK yang dimanfaatkan oleh masyarakat di kawasan Taman Nasional Siberut. Metode yang digunakan pada penelitian ini adalah wawancara, observasi lapang, dan studi literatur. Hasil penelitian menunjukkan bahwa masyarakat Desa Simatalu memanfaatkan tujuh spesies HHBK untuk kebutuhan subsisten dan komersial. Spesies HHBK tersebut meliputi rotan manau, madu, kopra, arang, sagu, pinang, dan cengkeh. Faktor-faktor seperti jenis kelamin, kelas umur, dan tingkat pendidikan memiliki kaitan terhadap pemanfaatan HHBK. Total nilai ekonomi yang didapatkan masyarakat desa dari pemanfaatan HHBK sebesar Rp. 10.061.679.969,7 per tahun., Communities around the forest are very dependent on forest products to meet their needs. One type of forest product utilized by the community is non-timber forest product (NTFP). The use of NTFP is a series of activities that include harvesting, processing and marketing of these forest product commodities. This study aims to describe the form of utilization and calculate the economic value of various NTFP species utilized by the community in the Siberut National Park area. The methods used in this study were interviews, field observations, and literature studies. The results showed that the people of Simatalu Village utilized seven NTFP species for subsistence and commercial needs. The NTFP species include manau rattan, honey, copra, charcoal, sago, areca nut and cloves. Factors such as gender, age class, and level of education are related to the utilization of NTFPs. The total economic value obtained by the village community from the utilization of NTFP is Rp. 10,061,679,969.7 per year.
Keyword: utilization, NTFP, community, economic value

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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