Judul: Aktivitas dan Produktivitas Lebah Trigona laeviceps di Kebun Polikultur dan Monokultur Pala (Myristica fragrans)
Abstrak: Trigona laeviceps is belong to the family Apideae. It has belong to no sting (stingless bee) and produce propolis, honey and bee pollen. This study aimed to study and compare the activity and productivity of Trigona laeviceps in polyculture and monoculture plantation nutmeg (Myristica fragrans). The study used completely randomized with type of garden (policultures and monocultures of nutmeg) Trigona activity and productivity (honey, pollen, propolis and development of colonies) were the variables and the obtained data were analyzed by ANOVA T - test with 95% confidence interval. observation the activity in and out in the morning until late afternoon (from 06:00 to 17:00), and productivity seen from the weight indication colony, honey, propolis and bee pollen. Trigona bee activity in the nutmeg monoculture plantation (83 %) was higher than in polyculture garden (84 %) and determined by light intensity. Activity in the garden polyculture affected by temperature pollen and propolis production percentages were higher in policulture plantation, while Trigona colonies in nutmeg monoculture had a better development. However, in this study, ambient factors (temperature, Rh, and light intensity) do not significantly determined variation in Trigona productions.
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Judul: Aktivitas Terbang dan Produktivitas Lebah Trigona laeviceps pada Bahan Stup Kayu Sengon dan Kayu Lapis (Plywood)
Abstrak: Trigona laeviceps is one of stingless bees species which produce propolis and its productivity influenced by flight activity of the workers. This study aimed to obtain stup material place Trigona hive which may improve the weight of bees colony and increase production of propolis. The weight gain of colony was counted every week while propolis+bee pollen and honey was measured at the end of the study. Temperature, internal temperature, relative humidity, light intensity and wind speed were also measured. Daily flight activity of Trigona for obtain pollen/resin and nectar/water on sengon stup was very significantly higher (p<0.01) compared to the bees kept in plywood stup (80.40±41.40 vs 42.33±21.90 bees/day). The light intensity affect the daily flight activity (R2=78.3% in sengon stup and R2= 85.6% in stup plywood). Colony weight gain on sengon stup was significantly higher (p<0.05) as compared to those on plywood stup (23.70 vs -−8.44 g/week). Whereas the production of propolis+bee pollen and honey were not significantly different (24.77 and 19.66 vs 19.92 and 17.61 g/8 weeks).
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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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