Judul: Analisis Keuntungan Usahaternak Sapi Perah (Kasus di Kelurahan Kebon Pedes, Kota Bogor
Abstrak: Indonesia’s milk production in 2012 equal 959.732 litre. Most of dairy cattle farmers in Indonesia run their business in small and medium scale. Productivity of dairy milk is closely related to the location of the farm. One of the location dairy farm in Bogor city is in Kebon Pedes sub-district. Dairy farm activities in Kebon Pedes sub-district been going on for decades. This area has an average temperature of 36o – 40o C and the unavailability of land as source of green feed making dairy milk productivity is not good. The results of this research showed milk productivity average by 10,51 litres per day. Cost of concentrate feed contributed the highest percentage of the total costs that equals to 49,33% of the total cost. Profit of dairy farm average by Rp.2.296,30 per litre and R/C ratio obtained 1,39. Feed cost factor and health cost factor significantly affect profitability of dairy farm business.
Keyword: profitability, dairy farm, dairy milk

Judul: Kinerja Usahaternak Sapi Perah pada Kedua Kelompok Ternak di Kelurahan Kebon Pedes, Kota Bogor
Abstrak: Dairy cows is one of animal husbandry that produce milk. The production of dairy cow milk in Indonesia is lower than the demand of milk. So, animal husbandary milk has good chance and prospect in business. Bogor is one of city in West Java which has numbers of family with lifelihood rely their family on animal husbandry business. There are two cattle farmers groups that still operate in Bogor, Kelompok Ternak Maju Terus („Maju Terus‟ Cattle Group) and Kelompok Ternak Sumber Makmur („Sumber Makmur‟ Cattle Group). The purpose of this research is to analyze the determinant factors of milk production and the influnce of milk production to business performance in both cattle group in Kebon Pedes, Bogor, West Java. The income approach and R/C ratio analysis are used to gain the research purpose. The result of this research are the determinant factors that statistically significant are the number of productive cows, the amount of feed both green feed and „waste‟ feed, otherwise concentrate is not statistically significant. The cattleman performance of („Maju Terus‟ Cattle Group is better than „Sumber Makmur‟ Cattle Group for the R/C ratio is higher.
Keyword: dairy cow, R/C ratio, income approach, performance

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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