Judul: Determinasi Status Hara N, P, K pada Jaringan Daun untuk Rekomendasi Pemupukan dan Prediksi Produksi Manggis
Abstrak: The objectives of this study were to find out the response of growth, yield and quality of mangosteen fruit on rate of nitrogen, phosphorus and potassium; find out the best mangosteen leaves as a sample of tissue analysis to determine nutrient status based on the mangosteen plant flush age and leaf position on the terminal flus; build the nitrogen, phosphorus and potassium fertilizer recommendation at productive mangosteen trees. This study consist of five separate experiments, ie: nitrogen fertilization experiment, phosphorus fertilization experiment, potassium fertilization experiment, determination of the mangosteen leaf samples based on flush ages and determination of the mangosteen leaf samples based on the position of the terminal leaves.
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Judul: Diagnosis Status Hara Menggunakan Analisis Daun untuk Menyusun Rekomendasi Pemupukan pada Tanaman Manggis (Garcinia Mangostana L.)
Abstrak: Mendiagnosis permasalahan hara utama (N, P, K) pada tanaman manggis dilakukan dengan dua pendekatan, yaitu analisis jaringan daun dan observasi gejala secara visual. Analisis jaringan daun untuk mendiagnosis status hara dan menentukan rekomendasi pemupukan bagi tanaman manggis dilakukan melalui tiga tahap percobaan. Percobaan pertama adalah uji korelasi antara konsentrasi hara daun dan hasil untuk mendapatkan umur daun yang tepat sebagai sampel. Sampel daun ini dipergunakan untuk uji kalibrasi. Percobaan kedua adalah uji kalibrasi untuk menentukan hubungan antara kisaran konsentrasi hara daun dengan hasil relatif tanaman. Percobaan yang ketiga adalah uji optimasi untuk mendapatkan dosis optimum untuk hasil maksimum. Pendekatan kedua, observasi terhadap gejala secara visual kekurangan dan kelebihan hara N, P dan K dilakukan pada bibit manggis, karena gejala tersebut sulit didapatkan pada tanaman manggis dewasa di lapangan. Status hara dan rekomendasi pemupukan pada bibit manggis ditentukan berdasarkan hubungan antara konsentrasi hara daun dan parameter pertumbuhan.
Keyword: Nitrogen, Fosfor, Kalium, Uji korelasi, Uji kalibrasi, Uji optimasi

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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