Judul: Pengaruh Aplikasi Kalsium dan Biopori terhadap Cemaran Getah Kuning dan Kualitas Buah Manggis (Garcinia mangostana)
Abstrak: Gamboge disorder is the major problem limiting marketable yield of mangosteen fruit. Soil calcium (Ca) application has been known to control the gamboge disorder, but the absorption of calcium occasionally becomes ineffective. The objectives of this research are to find the effect of calcium and biopore application to reduce gamboge disorder and increasing quality of fruit. This research was conducted from November 2010 to April 2011 in mangosteen farm at Karacak, Leuwiliang, Bogor and Postharvest Laboratory, Department of Agronomy and Horticulture IPB. The treatment design is based on Randomized Completely Block Design with two factors. The first factor was concentration of calcium and the second factor was biopore application. There were five concentrations of calcium; 0 kg Ca2+/tree/year; 5.33 kg dolomit/tree/year; 3.55 kg kalsit/tree/year; 10.67 kg dolomit/tree/year; 7.11 kg kalsit/tree/year and there were two treatments of biopore; without biopore application and with biopore application. The result showed that calcium factors were significant to reduce gamboge disorder, but the bi opore factors didn’t give significant effect to reduce gamboge disorder. Interaction between 7.11kg kalsit/tree/year with biopore technology were effectif to reduce gamboge disorder in mangosteen peel. In aril, interaction between 5.33 kg dolomit/tree/year with and without biopore technology, were give significant effect to reduce gamboge disorder in aril.
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Judul: Aplikasi kalsium untuk mengendalikan cemaran getah kuning pada buah manggis (Garcinia mangostana) di Bogor dan Purworejo)
Abstrak: Gamboge disorder is a main problem in mangosteen production. Result of previous researches showed that calcium fertilization could control gamboge disorder. This experiment was conducted to get lower effective dosage of calcium in two locations i.e., Bogor and Purworejo. The experiment was held from October 2013 to March 2014 in Leuwiliang-Bogor and Kaligesing-Purworejo. Observation of physical and chemical quality was conducted in Postharvest Laboratory, Department of Agronomy and Horticulture. The design of this expermient is Randomized Completely Block Design with one factor. The factor is calcium dosage: 0 kg Ca2+/tree, 1.5 kg Ca2+/tree, 3 kg Ca2+/tree. The result showed that application of calcium decreased the gamboge disorder in two locations. The effective dosage which could decrease the gamboge disorder in Bogor and Purworejo is 1.5 kg Ca2+/tree. The result also showed that application of calcium didn’t affect total soluble solid and total titrated acid.
Keyword: Bogor Agricultural University (IPB), Purworejo, Bogor, calcium, disorder gamboge, mangosteen

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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