Judul: Study of White Jabon (Anthocephalus cadamba) Growth in Gap Planting Research Plot PT. Sarmiento Parakantja Timber, Central Kalimantan
Abstrak: Sistem silvikultur Tanam Rumpang Tebang Rumpang (TRTR) diharapkan menjadi salah satu sistem silvikultur untuk merehabilitasi hutan alam terdegradasi. Penelitian ini bertujuan mengetahui pertumbuhan jabon putih yang ditanam dalam rumpang serta mengetahui pengaruh kemiringan lapangan terhadap pertumbuhan jabon putih. Metode penelitian menggunakan cara sensus dan pengukuran diameter dan tinggi total pohon jabon putih yang terdapat dalam 16 buah rumpang dengan luas masing-masing rumpang 2000 m^2. Hasil penelitian menunjukkan bahwa ukuran diameter berumur dua tahun adalah 7,42 cm dan tinggi total pohon rata-rata mencapai 651,11 cm. Uji statistik menunjukkan terdapat perbedaan nyata pengaruh kelerengan dengan jabon putih. Jabon putih tumbuh lebih baik pada kelas lereng curam dibandingkan dengan kelas lereng datar -landai dan sedang., The Gap Planting and Gap Cutting silvicultural system (TRTR) is expected to be one of the silvicultural systems to rehabilitate degraded natural forests. This study aims to determine the growth of white jabon planted in gaps and to determine the effect of slope on the growth of white jabon. The research method used the census and measured the diameter and total height of the white jabon trees contained in 16 gap plots of stump with an area of 2000 m^2 each. The results showed that the diameter at two years old was 7,42 cm and the average total height of the trees was 651,11 cm. Statistical tests showed that there were significant differences in the effect of slopes on white jabon growth. White Jabon grows better on steep slopes compared to flat-sloping and moderate slopes.
Keyword: Anthocephalus cadamba, forest degradation, gap planting, growth

Judul: Cost Analysis of Maintenance of White Jabon (Anthocephalus cadamba) in the Gap Planting Research Plot Area of PT. Sarmiento Parakantja Timber
Abstrak: Tanam rumpang merupakan salah satu metode untuk merehabilitasi hutan dan lahan terdegradasi. Tujuan dari penelitian ini adalah mengetahui biaya kegiatan pemeliharaan jabon putih pada areal rumpang dalam areal plot penelitian PT. Sarmiento Parakantja Timber. Metode yang digunakan dalam penelitian ini terdiri dari metode time study, analisis biaya, dan uji statisik menggunakan Uji Independent sample t-test. Hasil penelitian menunjukkan untuk menyelesaikan kegiatan pemeliharaan rumpang dengan luas 3,2 ha membutuhkan waktu 8-9 hari dengan jumlah pekerja sebanyak 3-4 orang. Tenaga kerja yang diperlukan untuk menyelesaikan kegiatan pemeliharaan rumpang yaitu sebesar 7,15 HOK per ha. Rata-rata biaya aktual pemeliharaan yaitu sebesar Rp. 2.627.124,41/ha, sedangkan biaya standar pemeliharaan sebesar Rp. 2.861.007,53/ha. Proporsi biaya pemeliharaan terbesar pada kegiatan pemupukan sebesar 81%, diikuti oleh penyiangan sebesar 13%, dan pendangiran sebesar 6%. Kondisi topografi datar-landai dan topografi sedang-curam di areal rumpang tidak mempengaruhi biaya total pemeliharaan aktual maupun standar., Gap planting is one method used to rehabilitate degraded forests and land. The purpose of this study was to determine the cost of maintaining white jabon in the gap area in the research plot area of PT. Sarmiento Parakantja Timber. The method used in this study consisted of a time study method, cost analysis, and statistical tests using the independent sample t-test. The results showed that it took 8-9 days to complete maintenance activities in an area of 3.2 ha with a total of 3-4 workers. The labor required to complete the maintenance of the gap is 7.15 HOK per ha. The average actual cost of maintenance is Rp. 2,627,124.41/ha, while the standard maintenance cost is Rp. 2,861,007.53/ha. The biggest proportion of maintenance costs was 81% for fertilizing activities, followed by 13% for weeding and 6% for post planting soil tillage . Condition of flat-sloping topography and moderate-steep topography in the gap area do not affect the actual or standard total maintenance costs.
Keyword: cost, maintenance, orest rehabilitation, gap planting

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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