Judul: Growth Evaluation of Sengon (Paraserianthes falcataria (L.) Nielsen) in Post-Mining Reclamation Land PT Berau Coal
Abstrak: Kegiatan reklamasi lahan pascatambang merupakan proses akhir dari kegiatan usaha pertambangan. Sengon (Paraserianthes falcataria (L.) Nielsen) umumnya digunakan sebagai tanaman pionir dalam reklamasi lahan pascatambang. Tujuan dari penelitian ini adalah mengkaji dan mengevaluasi pertumbuhan sengon pada 10 lokasi blok dan disposal dengan rentang tahun tanam 2012-2021 di SMO PT Berau Coal. Penelitian dilakukan dengan membuat plot pengamatan ukuran 40 m x 25 m pada setiap blok dan disposal. Tinggi dan diameter tertinggi teramati pada sengon dengan tahun tanam 2012 sebesar 21 m dan 40,44 cm, sedangkan nilai terendah teramati pada sengon dengan tahun tanam 2021 sebesar 6,86 m dan 9 cm. Tinggi bebas cabang dan luas proyeksi tajuk tertinggi teramati pada sengon dengan tahun tanam 2014 sebesar 8,2 m dan 454,36 m2 dan terendah pada sengon dengan tahun tanam 2021 sebesar 2,15 m dan 67,44 m2. Hasil analisis regresi positif teramati pada hubungan antara luas proyeksi tajuk dengan tinggi bebas cabang dan diameter serta tinggi dengan diameter sengon. Performa pertumbuhan sengon di Sambarata Mine Operation termasuk kategori baik jika dibandingkan dengan pertumbuhan sengon yang ditanam secara monokultur di Jawa Barat.
Keyword: monoculture, post-mining, reclamation, revegetation, sengon

Judul: Pertumbuhan Bibit Sengon (Paraserianthes falcataria (L) Nielsen) pada Media Bekas Tambang Pasir dengan Pemberian Subsoil dan Arang Batok Kelapa
Abstrak: Exploitation of natural resources in order to meet the increasingly commonplace as the needs of the population increase. Exploitation are likely to cause environmental damage. One such activity is the mining of sand. River sand mining will lead to a sustained decrease in the amount of sand in the river bed. As a result, the river will be damaged by excavation continues. In addition to damaging the ecosystem of the river, sand mining has also led to a decrease in water quality and air pollution. In order to reduce the impact of damage, utilization and processing of mining waste as a growing medium in a first step into alternative revegetation can be done. However, low nutrient content and CEC and texture of sand dominated an obstacle in the utilization of tailings sand as a growing medium. Application subsoil and the addition of coconut shell charcoal is expected to help improve these constraints. Sengon is a very fast growing plant and has a high potential and has been widely known to the public. These plants are best used in the post-mining land rehabilitation. The results showed that the addition of the interaction of subsoil and coconut shell charcoal gives the best growth of influence. Interaction addition of 75% subsoil and charcoal 40 g (a3b2) is the best treatment to improve seedling height by 64%. While the increase in diameter increment, the interaction of subsoil 75% and the addition of 60 g charcoal (a3b3) is the best treatment with the addition of a diameter of 87.50%. The best treatment for weight parameters in total bases (BKT) and total dry weight (BKT) indicated by the treatment (a3b3) with a 63.49% increase% and 36.10%. Giving a single charcoal best in show at the addition of 60 g charcoal (a0b3). Indicated by a high addition of 47.32%. While granting subsoil singly not give significant effect on seedling growth.
Keyword: sengon, subsoil, Charcoal, mining sand

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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