Judul: Analisis Usaha Pengrajin Tahu Sumedang Sebelum dan Setelah Kenaikan Harga Kedelai (Studi Kasus: Kecamatan Tanjungsari, Sumedang)
Abstrak: Soybean is one of the food that the price level is fluctuated. The soybean price increase will affect the soybean processing industry, one of which is tofu industry. The soybean prices increase are expected to affect the structure of cost, revenue, profit, and the efficiency of a business. This research aimed to analyze of tofu industry business before and after the soybean price increase. The method that used in the study was a census method. Data were analyzed quantitatively and qualitatively. The analytical tool used is the R / C ratio, paired t-test, and anova test. The results of the analysis of a total of 20 respondents showed that the soybean price increase has effect on the cost, revenue, profit, and the R/C ratio, as well as with an internal analysis of business scale. However, the results of the analysis at different levels of scale of business is no different. This is due to the small sample size in each scale of business and strategy performed relatively the same at every scale of business, so it can not represent the whole population in the District Tanjungsari, Sumedang.
Keyword: the soybean price increase, profit, efficinecy, different test, cost

Judul: Dampak Kenaikan Harga Kedelai Terhadap Tiga Usaha Kecil dan Menengah Tahu Kota Bogor
Abstrak: Inability to meet the needs of domestic soybeans make Indonesia dependence on imports. Consequently there is no certainty of domestic supply availability and price stability of soybean. The increased price of soybeans in the country influenced by the world soybean prices often occur and cannot be avoided by tofu industries that are consumers of imported soybeans. With the diversity of tofu business scale existing in Indonesia, the impact of rising soybean prices will vary from one tofu business to others. Therefore, this study uses three samples with different scale business to compare the impact of rising soybean prices. Classification of used business scale is based on the amount of daily production capacity, that is the scale of households with a daily production capacity of ≤ 100 kg, small scale with a daily production capacity of 101-200 kg, and medium scale with a daily production capacity of 201-300 kg. The indicators used in this study is the profitability value, value-added and sensitivity. The results obtained are that v medium-sized tofu businesses generate the highest profitability value and valueadded, and are the most resistant tofu business in encountering the increased soybean prices. However, the results obtained by medium-sized tofu businesses are not much different from the value obtained by small-sized tofu businesses. Thus, in this study, small and medium-sized tofu business generate insignificantly different profitability value, value-added, and the sensitivity.
Keyword: Bogor Agricultural University (IPB), tofu, profitability, value added, soybean price fluctuations

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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