Judul: Structure and Composition of Shorea pinanga Stands in the KHDTK Haurbentes, Bogor
Abstrak: Hutan tanaman shorea pinanga di luar habitat sudah ditanam sejak 1940 di KHDTK Haurbentes, Bogor. Seperti apakah regenerasi alami dan struktur tegakan yang terjadi di kawasan tersebut. Tujuan penelitian adalah menganalisis proses regenerasi alami pada tegakan S. pinanga. Penelitian menggunakan metode analisis vegetasi di lima petak penelitian yaitu petak 11, 12, 68, 72, dan 100 dengan masing-masing petak dibuat dua plot pengamatan. Hasil penelitian menunjukkan bahwa hutan tanaman S. pinanga berumur tua telah membentuk struktur tegakan seperti hutan alam dengan bentuk kurva “J terbalik”. Permudaan alami S. pinanga ditemukan di semua petak penelitian. Petak 11, 68 dan 72 diperoleh kemiripan struktur tegakan S. pinanga untuk tingkat semai dan pohon., Shorea pinanga out-of-habitat plantations have been planted since 1940 at KHDTK Haurbentes, Bogor. What is the natural regeneration and stand structure that occurs in the area. The research objective was to analyze the natural regeneration process in S. pinanga stands. The research used the vegetation analysis method in five research plots, namely plots 11, 12, 68, 72, and 100 with each plot made two observation plots. The results showed that old-growth S. pinanga plantations have formed a stand structure similar to natural forests with an "inverted J" curve. Natural sprouts of S. pinanga were found in all study plots. Plots 11, 68 and 72 were similar to S. pinanga stand structure at seedling and tree levels.
Keyword: Hutan tanaman, Shorea pinanga, struktur tegakan, regenerasi alami

Judul: Struktur dan Komposisi Tegakan Hutan Tanaman  Shorea leprosula Miq. di KHDTK Haurbentes, Bogor
Abstrak: Shorea leprosula Miq. (meranti merah) merupakan salah satu jenis dari famili Dipterocarpaceae. Proses regenerasi S. leprosula dapat diketahui dengan mempelajari struktur dan komposisi jenisnya. Keberadaan jenis ini mengalami penurunan sehingga perlu dilakukan kegiatan konservasi. Penelitian ini bertujuan menganalisis struktur dan komposisi jenis pada areal tegakan S. leprosula dan kondisi permudaannya. Pengambilan data dilakukan di KHDTK Haurbentes pada petak 32b, 35, 82, 83, dan 84 yang didominasi tegakan S. leprosula. Hasil penelitian menunjukkan jumlah pohon terbesar berada pada kisaran diameter pertengahan dengan grafik sebaran diameter cenderung berbentuk lonceng. Stratifikasi tajuk terdiri atas stratum A, stratum B, dan stratum C yang didominasi oleh jenis S. leprosula, S. stenoptera, dan S. pinanga. Berdasarkan hasil identifikasi ditemukan sebanyak 257 individu pohon yang meliputi 9 jenis, dari 4 marga, dan dari 3 famili. Permudaan S. leprosula memiliki jumlah yang banyak dan mendominasi pada semua petak pengamatan., Shorea leprosula Miq. (red meranti) is a species of the family Dipterocarpaceae. The regeneration process of S. leprosula can be known by studying the structure and composition of its type. The existence of this type has decreased so that it is necessary to carry out conservation activities. This study aims to analyze the structure and type composition of the S. leprosula stand area and its youth conditions. Data collection was carried out at KHDTK Haurbentes on plots 32b, 35, 82, 83, and 84 dominated by S. leprosula stands. The results showed that the largest number of trees was in the mid-diameter range with a diameter distribution chart tending to be bell-shaped. The heading stratification consists of stratum A, stratum B, and stratum C which are dominated by the types S. leprosula, S. stenoptera, and S. pinanga. Based on the identification results, 257 individual trees were found, including 9 types, from 4 clans, and from 3 families. S. leprosula youth has a large number and dominates on all observation plots.
Keyword: youth, S. leprosula, structure of stands

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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