Judul: Penyadapan Getah Pinus dengan Metode Bor di Hutan Aek Nauli Kabupaten Simalungun Provinsi Sumatera Utara
Abstrak: Pine tapping at Aek Nauli have been done using quarre method, the disadvantage of this method is the damage of tree stem because of a large area which tapped. The disadvantage of quaree method can be substituted by using another method like drill method. The aimed of study is to measure the productivity of pine resin tapping with the drill method and apply stimulants. The study was conducted with 4 different treatments, there are treatment A using the quarre method without stimulants as a control, treatment B using quarre method with stimulants, treatment C using the drill method with a pipe and stimulants, and treatment D using the drill method with a tap gutter and stimulants at Aek Nauli Simalungun District North Sumatera. The results showed that the quarre method by applying stimulants produces the highest production of pine resin. But for the application of pine resin tapping in Aek Nauli is better to use the drill method with a tap gutter that provides minimal impact damage to trees and the forest in Aek Nauli as Water Absorption Area.
Keyword: stimulant, productivity, pine resin, drill method, Bogor Agricultural University (IPB)

Judul: Produktivitas Penyadapan Getah Pinus dengan Metode Bor tanpa Pipa
Abstrak: Drill method is a method of tapping that gives many advantages but also has many deficiency, such as the use of pipes is not efficient and add more costs, it also difficult to move the resin from the receptacle into a drum, and it can’t accommodate the resin which came after the tapping period. This research uses five different treatments. Treatment A by using the quarre method without stimulansia as a control, treatment B by using the quarre method with stimulansia, treatment C by using the drilling method with a pipe, treatment D by using drilling method without a pipe, and treatment E by using the drill method with a pipe and resin shelters not on a pipe. The tree sample used in every treatment is 10. The research shows that the treatment D by using drill method without a pipe gives the highest resin productivity however it has more water content and higher levels of impurities than the other drill method designed. Thus, drill methods without a pipe, is a tapping solution that capable of producing qualified resin also has not destructive to trees compared to the quarre method. It also can produce more resin with an economical and practical surplus than the drill method by using a pipe.
Keyword: quality, productivity, pine resin, drill method

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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