Judul: Penentuan Sistem Silvikultur Berbasis pada Proses Pemulihan Vegetasi dalam Teknik Silvikultur Intensif (Studi Kasus di Areal PT Sarpatim, Kalimantan Tengah)
Abstrak: Mistakes in implementing the right silvicultural system with forest characteristic cause forest degradation. The aim of this observation is to determine the appropriate silvicultural system based on the forest standing structure and similarity of community. The analyzed data’s composition’s type and forest standing structure, forest regeneration type composition, type variety index value, ordination showed by important value index and community dissimilarity index, and cluster and biplot analysis. The result shows that non-Dipterocarpaceae commercial type community has the biggest density and proportion in all levels. Forest standing structure shapes J-reversed curve. The variety on all plots is high enough. Ubar and red meranti dominate all observation plots. Almost tree community has relatively different types in each plot. Regeneration community almost all has value for ID <50% that means the community is relatively the same. It can be seen from cluster analysis chart which part of three grup. The biplot analysis result shows that TJ6 has the most similarity between recovery and tree, while the other plots have different composition.
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Judul: Pemulihan Vegetasi di Areal Hutan yang Dikelola dengan Sistem TPTJ (Studi Kasus di Areal IUPHHK-HA PT. Suka Jaya Makmur, Kalimantan Barat)
Abstrak: Massive utilization of forest resources became one factor which caused degradation on natural forest. Forest degradation which occurred continuously could cause a change in forest composition. This could happen because seedling from invasive species dominated the area of natural forest. This research aimed to determine the composition and structure recovery of forest stands managed by TPTJ system on area of IUPHHK-HA PT. Suka Jaya Makmur, West Kalimantan. The results showed that non-commercial Dipterocarp species group had the biggest value of density and proportion among all levels Dipterocarp. Curve diameter distribution showed a balanced logged forest. The diversity in all plotarea was high. Kelampai and meranti were dominated in canopy level. Jambu monyet and kelampai were the species that dominated in seedling level. Tree and seedling had a different composition, it was shown by the ID value at >50%. This was shown by cluster analysis which divided into four groups. Commercial species proportion was generally larger than other non-commercial species.
Keyword: selective cutting and line planting, vegetation recovery, forest utilization

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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