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: Uji Penanaman Menggunakan Teknik Direct Seeding di Lahan Bekas Tambang Batu Kapur, Gunung Putri, Bogor
Abstrak: Kegiatan reklamasi dan rehabilitasi penting dilakukan untuk mengembalikan daya dukung lahan agar berfungsi kembali sesuai dengan peruntukannya. Inovasi dalam kegiatan reklamasi dan rehabilitasi lahan bekas tambang perlu dilakukan untuk mempercepat dan meningkatkan keberhasilan dalam mengembalikan fungsi lahan sesuai peruntukannya. Salah satu bentuk kegiatan reklamasi dan rehabilitasi lahan bekas tambang adalah revegetasi. Direct seeding adalah teknik penanaman dengan menggunakan benih yang ditanam langsung di lapangan tanpa melalui tahapan pembibitan di persemaian. Penting untuk menganalisis pertumbuhan tanaman yang ditanam menggunakan teknik direct seeding dan penanaman menggunakan semai. Kedua teknik tersebut diujicoba untuk merehabilitasi lahan bekas tambang batu kapur PT. Solusi Bangun Indonesia di Bogor. Benih dan bibit yang digunakan dalam penelitian ini adalah merbau (Intsia bijuga), ketapang (Terminalia catappa), jengkol (Archidendron jiringa), bisbul (Diospyros blancoi), dan nangka (Artocarpus heterophyllus). Rancangan percobaan yang digunakan adalah Rancangan Acak Lengkap (RAL) dengan kombinasi metode penanaman dan pemupukan serta lima jenis tanaman sebagai perlakuan. Benih dan bibit kelima tanaman tersebut ditanam di lahan bekas tambang batu kapur dengan kondisi tanah yang didominasi fraksi pasir. Hasil penelitian menunjukkan bahwa tanaman yang ditanam dengan teknik direct seeding memiliki persentase bertahan hidup dan rata- rata pertumbuhan tanaman yang sama bahkan cenderung lebih baik dibandingkan dengan tanaman yang ditanam menggunakan bibit polybag. Jenis tanaman yang dapat ditanam menggunakan teknik direct seeding di lahan terbuka bekas tambang batu kapur adalah nangka dan merbau, sedangkan jengkol kurang mampu bertahan pada kondisi lingkungan yang kering, ketapang yang ditanam menggunakan teknik direct seeding rentan terhadap serangan hama yang menyebabkan benih gagal berkecambah, dan bisbul yang memiliki pertumbuhan kurang baik walaupun persentase hidup dan daya berkecambahnya tinggi. Penanaman menggunakan teknik direct seeding mampu menghemat biaya penanaman dibandingkan menggunakan bibit tanaman hingga 65%. Berdasarkan uraian diatas dapat disimpulkan bahwa teknik direct seeding menggunakan jenis nangka dan merbau dapat dilakukan untuk mempercepat reklamasi dan rehabilitasi lahan bekas tambang batu kapur dan menghemat biaya operasional penanaman., Reclamation and rehabilitation activities are carried out to restore the land function according to its designation. Innovations in reclamation and rehabilitation of ex-mining land need to be carried out to accelerate and increase success in restoring land functions. One form of reclamation and rehabilitation of ex-mining land is revegetation. The direct seeding technique is a planting method using seeds planted directly in the field without going through nursery stages. It is important to analyze and find out wether the direct seeding technique has better plant growth when compared to planting using seedlings. The technique was tested to rehabilitate ex-limestone mining of PT. Solusi Bangun Indonesia in Bogor. The seeds and seedlings used in this study were Merbau (Intsia bijuga), ketapang (Terminalia catappa), jengkol (Archidendron jiringa), bisbul (Diospyros blancoi), and jackfruit (Artocarpus heterophyllus). This experiment design used was a completely randomized design (CRD) with combination of planting methods and fertilizer as well as five tree species as treatments. The seeds and seedlings are planted on ex-limestone mining land which has soil with a dominant sand fraction. The results showed that plants grown using the direct seeding technique had a higher survival rate than seedlings, except for ketapang. The growth of plants grown using the direct
Keyword: Direct seeding, Ex-limestone mining land, Reclamation, Seedlings

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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