Judul: Effects of the Price Increase of Soybean on Profitability of Small and Micro Businesses Sanan, Tempe Chips, Malang City.
Abstrak: Salah satu komoditas yang membuat Indonesia bergantung pada impor agar ketersediaannya selalu ada adalah kedelai. Akibatnya harga kedelai impor tidak terjaga kestabilannya. Kenaikan harga kedelai impor di dalam negeri disebabkan beberapa faktor seperti melemahnya nilai tukar rupiah terhadap dolar dan kenaikan harga kedelai di pasar dunia. Dampak naiknya harga kedelai adalah berkurangnya profitabilitas UMKM keripik tempe pada masing-masing skala usaha. Tujuan dari penelitian ini untuk mengetahui profitabilitas masing-masing skala usaha dan mengetahui skala usaha yang paling bertahan pada penurunan ukuran tempe. Profitabilitas usaha dihitung dengan perhitungan titik impas, Marginal Income Ratio (MIR) dan Marginal of Safety (MOS) serta dilakukan perhitungan analisis sensitivitas untuk mengetahui skala usaha yang paling bertahan pada penurunan ukuran tempe. Hasil yang diperoleh adalah usaha dengan kapasitas produksi keripik tempe paling besar tidak memiliki profitabilitas tertinggi dan tidak tahan terhadap penurunan ukuran tempe. Usaha mikro lebih menguntungkan dan lebih mampu bertahan jika dibandingkan dengan usaha kecil.
Keyword: Bogor Agricultural University, Institut Pertanian Bogor, IPB, MOS, MIR, Business scale, Sensitivity analysis, UMKM, Break even point, Smail enterprises, Small businesses, Soybean

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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