Judul: Analisis Corak Pengembangan Usaha Tani Ubi Jalar Serta Faktor-Faktor yang Mempengaruhinya (Studi Kasus Desa Cikarawang dan Desa Purwasari Kecamatan Dramaga Kabupaten Bogor)
Abstrak: The massive growth of sweet potato downstream industries in Indonesia has triggered the excalation of sweet potato availability as derivated product ingredient. Almost seventy percent of national sweet potato production was processd by industries. It leads to sweet potato intensification to increase its level of commercialization. However the uneven distribution of Indonesia economy contribution leads to a different infrastructure and market accessibility development. This study that was conducted in two villages namely Cikarawang and Purwasari aimed to identify the level of commercialization of sweet potato farming due to differences in infrastructure and market accessibility and to analyze the factors that affect the level of commercialization of sweet potato farming. Cikarawang has a closer market accessibility and better infrastructure than Purwasari. The result showed that level of commercialization of sweet potato farming in Cikarawang higher than level of commercialization of sweet potato farming in Purwasari (60.58 persent for Cikarawang and 49.84 persent for the Purwasari ). This indicated that the level of commercialization of swet potato farming was determined by infrastructure and market accessibility. The significant factor that influence level of commercialization of sweet potato farming in both two villages are land , farmer family size, and the price of sweet potato.
Keyword: sweetpotato., market accessibility, level of commercialization, infrastructure, Bogor Agricultural University (IPB)

Judul: Sistem Pemasaran dan Nilai Tambah Produk Olahan Ubi Jalar (Ipomoea batatas, L.) di Desa Cikarawang dan Desa Petir, Kecamatan Dramaga, Kabupaten Bogor
Abstrak: Sweet potato is a source of carbohydrat and protein, relatively inexpensive for consumption. The farmers had high dependency to the middleman, the lack of market access and price information in farmer’s level lead the bargaining position of the farmers low, and the activity of sweet potatoes processing. Therefore, the research is conducted to determine the marketing systems and value-added of processed sweet potato product. The objective of this research is to analyze the agency and functions of marketing, marketing channel, market structure and market behavior; to analyze marketing margin, farmer’s share, and the ratio of benefits to costs; to calculate value-added of dumpling, flour, and cracker. Data collection was held by observation and interviews to the farmers and entrepreneurs of processed sweet potato products in the Cikarawang village and Petir village by purposive sampling method, whereas for the marketing agency data collection was held by following the flow of information from the previous marketing agency and purposive sampling. The results are shown that the third channel was relatively efficient to distribute grade A and B sweet potato, while the first channel was relatively efficient to distribute grade C sweet potato. The results of value added analysis of processed sweet potato products have shown that the value added ratio and profit level of dumpling was the highest than other processed sweet potato products.
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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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