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: Kajian Klasifikasi Usahatani Ubi Jalar pada Petani Kecil Berdasarkan UU No.20 Tahun 2008, (Studi Kasus di Desa Cikarawang, Kecamatan Dramaga, Kabupaten Bogar, Provinsi Jawa Barat)
Abstrak: Sweet potato has potential as a diversified source of high carbohydrate food, can be used as a food chart, pakanm and industrial raw materials. Reviewing the size of the business in commodity sweet potatoes in pespektif SMEs considered important, sweet potato farming in the perspective of SMEs is measured by net worth and the value of revenues per year, but in the measurement of economic studies of a business can be calculated based on the performance of its business. By using the performance measures the government is much easier to classify a business in specific groups according essence helps policies potentially weak. So to know the circumstances of this research attempts to review the actual conditions experienced sweet potato farming on small farmers as one economic agent in Indonesia. Selection of study sites and respondents were purposively. The required data are the primary data and secondary data, and then analyzed quantitatively using microsoft office exel and the results were analyzed qualitatively. analysis shows the performance of farms in the "small farmers" with an average land area of 0:21 ha penelitain location, shows that farming is done "small farmers" is a productive business with the R / C 1.34 against cash cost or value of R / C 1:10 of the total costs and benefits with cash receipts amounted to USD 2 384 578.34 per year or total revenues of Rp 769 262.95 per year. And in the perspective of SMEs klasifiaksi net sales and net assets for the year in the small farmers of the research included in the scale "micro-enterprises". Microenterprises have a great amount of effort, but it has a weak economic structure in which a low value product, which is not a legal form of business, and education level were rendah.Maka businesses to achieve the essence of policies that help those who are structurally weak, the government needs to review back perspective of classification MSMEs (Micro, Small, and Medium Enterprises) in Article 6 of Law No. 20 of 2008 in order to adapt to the actual conditions, or existing definitions can be added into UGMKM (landless Enterprises, Micro, Small and medium enterprises).
Keyword: Bogor Agricultural University (IPB), business performance., policy, the size of SMEs, Small farmers

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.
Keyword: