Judul: Pengembangan teknik pengadaan bibit jenis lokal untuk rehabilitasi lahan bekas tambang PT Bukit Asam Tbk
Abstrak: Mining activities have negative effects for environment directly. The effect such soil surface layer exposure which increase erosion rate and surface run-off, disturbance of land stability rate and destruction of forest ecology. Mine rehabilitation intends to improve disturbed land that resultant of mining activities so that it can be useful as its function. Rehabilitation activities in PT Bukit Asam Tbk were aimed to revegetation. Revegetation needs great number of seeds were used better adaptability. However, local seeds expansion has not done yet by PT Bukit Asam Tbk. Thereupon, this research intend to find the most suitable multiplication technique for local plant that will promote for rehabilitation in the land ex mining.
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Judul: Pengembangan Penggunaan Metode Direct Seeding untuk Rehabilitasi Lahan Pasca Tambang PT Tunas Inti Abadi, Kalimantan Selatan
Abstrak: The method of direct seeding is developed in post mining land in order to give the opportunity to seeds to early adapt with extreem condition in post mining land. This method is implemented in impermanent reclamation land by small mining enterprises caused of its cheap operational cost. The objective of this research is to find out the efficiency of direct seeding method and the suitability of four species; trembesi (Samanea saman), sengon (Falcataria moluccana), sengon buto (Enterolobium cyclocarpum), and randu (Ceiba pentandra) in reclaiming post mining land. The research was conducted implementating three experiments: Experiment I implemented Seeds Physical and Physiological Quality Testing, Experiment II is Forest Species Seeds Adaptation in Post Mining Land, and Experiment III is Effect of Manure Addition in Seed Germination and Growth of Direct Seeding Results. Seed physical quality testing with 1000 grain weight method used the seeds which are classified into small size seeds (sengon and randu) and medium size seeds (trembesi and sengon buto). Based on physiological quality testing, the result of experiment I is 66.67% - 86.67%, Experiment II is 11.2% - 31.6%, and Experiment III is 7.2%-13.2%. Manure addition has significantly influenced the height and diameter growth in Experiment III, but not to the survival rate of plantation. In Experiment II, at the age of twelve weeks, the height of randu plantation was 9.6 cm; trembesi 7.9 cm; and sengon 3.6 cm. The diameter of sengon buto was 4.35 mm; randu 2.12 mm; trembesi 1.91 mm; and sengon 0.98 mm. The result of Experiment III is that average height of sengon buto was 41.5 cm; trembesi 15.4 cm; randu 12.4 cm; and sengon 7.4 cm. The diameter of sengon buto was 5.46 mm; trembesi 2.47 mm; randu 2.42 mm; and sengon 1.12 mm. The survival rate based on the plantation hole in Experiment II was the survival rate of randu and sengon was 66%; trembesi 58%; and sengon bruto 52%. In Experiment III, the higest survival rate was trembesi 72% followed by randu 40%, sengon 38% and sengon buto 28%. From the result of these four species used in the experiment, all of the species are highly adaptive with extreme condition in post mining land and suitable to implement with direct seeding method. It is also identified that size of seed highly influenced the successfulness of direct seeding. Small size seeds are the most suitable one in competition with weed. Direct seeding is more economic with plantation cost of 2 million rupiahs per hectare compared with conventional seeding method with cost of 4.487.500 rupiah per ha.
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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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