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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Judul: Kekonsistenan Hamiltonian pada Gerak Gelombang Interfacial
Abstrak: The interfacial wave is an internal wave that occurs at boundary of two layers fluid. It appears because there is difference of mass density between the two layers. The objective of this thesis is to formulate the motion of internal wave with flat base and flat as well as free upper bound surface. The motion equation obtained is a Hamiltonian system. The Hamiltonian in this system is expressed by variable of wave deviation and horizontal component of potential velocity. Under assumption that interfacial wave moves only in one direction, it can be shown that the Hamiltonian depends on the solution of the wave motion equation. The coefficients of the equation depend on the physical characteristics of the two layers of fluid, i.e. thickness and mass density. The numerical results show that Hamiltonian in the system is constant. It is consistent with Hamiltonian characteristic, which does not depend on time.
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Judul: Keragaman 28 Genotipe Cabai (Capsicum annuum L.) dari Berbagai Grup dan Ketahanannya terhadap Penyakit Antraknosa yang disebabkan oleh Colletotrichum acutatum S
Abstrak: Tantangan utama dalam meningkatkan produktivitas cabai Indonesia adalah gangguan penyakit antraknosa. Antraknosa pada cabai disebabkan oleh patogen dalam genus Colletotrichum. Studi tentang keragaman dan seleksi ketahanan tanaman cabai terhadap penyakit antraknosa perlu dilakukan guna memperoleh informasi genetik dalam merakit varietas cabai yang berdaya hasil tinggi dan tahan penyakit antraknosa. Pada penelitian ini dilakukan dua kegiatan yaitu karakterisasi daya hasil dan evaluasi ketahanan terhadap antraknosa. Penelitian dilakukan pada bulan Maret 2011 – September 2011 di lapangan dan laboratorium. Kegiatan karakterisasi daya hasil menggunakan 28 genotipe cabai. Karakter yang diuji untuk karakterisasi daya hasil yaitu karakter kualitatif dan kuantitatif. Pada karakter kuantitatif dilakukan pengamatan terhadap peubah tinggi tanaman, tinggi dikotomus, panjang daun, lebar daun, umur berbunga, umur panen, bobot buah per tanaman, bobot per buah, panjang buah, diameter buah, dan tebal daging buah. Dua puluh delapan genotipe yang diuji sangat beragam. Genotipe yang memiliki bobot buah per tanaman tertinggi adalah IPB C143 (860.26 g) dan IPB C5 (817.16 g). Genotipe IPB C20 memiliki bobot buah per tanaman terendah, yaitu 177.46 g. IPB C143 merupakan genotipe dengan bobot per buah paling tinggi, yaitu 17.20 g. IPB C120 merupakan genotipe yang memiliki panjang buah tertinggi, yaitu 22.09 cm. Genotipe yang memiliki tebal daging buah tertinggi, yaitu IPB C151 (0.29 cm) serta genotipe IPB C145 dan IPB C76 memiliki tebal daging buah terendah, yaitu 0.09 cm. Diameter buah tertinggi dimiliki oleh genotipe IPB C143 (2.08 cm), sedangkan diameter buah terkecil dimiliki oleh genotipe IPB C172 (0.62 cm)....dst
Keyword: cabai, keragaman, ketahanan, antraknosa, colletotrichum acutatum