Judul: Kajian Resistensi Lima Jenis Beras Varietas Lokal Terhadap Serangan Sitophilus zeamais Motsch.
Abstrak: The present study was conducted to evaluate resistance of local rice varieties i.e. Batutegi, Silugonggo, Ciherang, Mamberamo and Indragiri from the attack of post harvest pest Sitophilus zeamais Motsch. The research was divided into two stages, the preparation and the experiments. In the preparation, S. zeamais culture was cultured to get adult S. zeamais aged 7-14 days. In the first experiment, 10 adult insects aged 7-14 days were infested for 7 days. The adults were then removed and discarded. The infested grains were incubated to allow the emergence of progenies. The emerged progenies were counted daily till there was no emergence for 5 days consecutively. From this experiment, the parameters were number of progenies (Nt), development period (D), development index (ID), intrinsic rate of increase (Rm) and weekly multiplication capacity (λ). In the second experiment, 100 gram of rice was infested with 25 adults of S. zeamais for 5 weeks. From this experiment, the parameters used were percentage of weight loss and percentage of holed grain. Based on number of progenies (Nt), development index (ID), intrinsic rate of increase (Rm), weekly multiplication capacity (λ), percentage of weight loss and percentage of holed grain, showed that Silugonggo variety was the most resistance among other tested rice varieties. The values are 57, 12.5239, 0.3781, 1.4596, 10.94%, and 12.45% respectively.
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Judul: Resistensi Relatif Beras Pecah Kulit dan Beras Sosoh Lima Varietas Padi asal Banyumas terhadap Serangan Sitophilus oryzae
Abstrak: The purpose of this study was to examine the resistance level of five different variety of brown rice and milled rice from Sitophilus oryzae attack during storage. Five varieties of rice that examined were Pandanwangi, Inpari 13, IR-64, Situ Bagendit, and Srikandi which all were planted in Banyumas region. This research was conducted in two experiments. The first experiment is done to measure the growth of Sitophilus oryzae during storage, while the second experiment is done to measure the rate of loss during storage. In the first experiment, 200 seeds of rice was infested by 5 couples of Sitophilus oryzae aged 7-15 days and kept for 7 days. The insects were then removed and the rice was observed every day for 14 days for emergence of the first generation (F1) of insects. The progenies were counted every day until there were no emergence for five consecutive days. The experiments were conducted in three replications. From this experiment, the parameters were number of progenies (Nt), development period (D), development index (ID), intrinsic rate of increase (Rm), and weekly multiplication capacity (λ). In second experiment, 100 g of rice infested by 25 insects and stored for 6 weeks. After 6 weeks, insects were removed and the storage loss were determined. In this second experiment, the parameters observed were percentage increase of water fraction, the loss of dry matter loss, and percentage of frass. Those two experiments were conducted in three replication. According to this experiment, Srikandi rice has the highest resistance towards Sitophilus oryzae attack among other varieties.
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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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