Judul: Daya Saing Ubi Kayu Olahan Kering Indonesia di Pasar Internasional
Abstrak: Indonesia is the third largest exporter of cassava dried in the world. More than 80 percent of Indonesia’s cassava dried product are exported to China. Inspite of the productivity of Indonesia cassava that is increasing in rate of 5.22 percent per year, the export volume has decreased in rate of -4.4 percent per year. The purpose of this study is to analyze the market share behavior and the comparative advantage of Indonesia cassava dried product in the International market. The time series data used in this study and the Revealed Comparative Advantage (RCA) method used to analyze the data. Market share of cassava dried Indonesia in China around 1 to 8 percent (2001-2013), with -8 percent/year growth rate. It means Indonesia market share has dropped. Currently, Indonesia cassava dried market share in China around 1percent. Thailand is the biggest competitor of cassava dried Indonesia Cassava dried Indonesia has a comparative advantages in the international market (2004-2011), depend on RCA value which is more than 1. The RCA value of cassava dried Indonesia around 8.40 (2004) to18.38 (2010).
Keyword: Bogor Agricultural University (IPB), RCA, Comparative Advantages, Cassava

Judul: Analisis Daya Saing Ubi Jalar Indonesia di Pasar Internasional
Abstrak: Agriculture sector in Indonesia has an important role and big contribution to Gross Domestic Product(GDP).Crop sub sector has the most important part in GDP of agricultural sector. Development of this sub sector such as sweet potatoes is one of the solutions for achieving food security and poverty alleviation in Indonesia. Sweet Potatoes has an important role in food self-sufficiency through diversification program. Indonesia is one of the top five sweet potatoes producers and exporters in the world. The aim of this study is to analyze competitiveness of Indonesian sweet potatoes. This study can be a reference for policy maker related to Indonesian competitiveness in international market. This study use Herfindahl Index and Concentration Ratio (CR) to analyze market structure. Besides that, this study used RCA (Revealed Comparative Advantage) and Porter Diamond’s model to explain comparative and competitive advantages. The result of this study shows that the average of HI value in 2001 to 2010 is 1457.92. This value is between 1110.80 and 2231.99 so that can be categorized sufficiently concentrated.CR4 is analyzed for USA, China, Indonesia, and Israel. CR4 value is more than 40% (60.30%) which has similar mean to the HI value. Therefore this value supports the HI.According to RCA Index, during 2001-2010 periods Indonesia has a strong comparative advantage in sweet potatoes. This can be seen from high RCA index (more than one). Competitive advantage is used to explain Indonesian sweet potatoes problems in international market. Porter Diamond’s model is one of the methods to analyze these internal and external factors of Indonesian sweet potatoes industry. There are four internal factors; (1) Resources such as natural, human resources, financing, information and technology, and infrastructure,(2) demand,(3) related and supporting industry, (4) competitiveness, structure, and firm strategy, and two external factors; (1) government role, and (2) opportunity. The results revealed that natural resources, human resources, domestic demand, government intervention, and opportunity to export are supporting factors to increase competitive advantages. However, there are still several weaknesses such as information and technology, infrastructure, financing, related industry, tight competition and market structure.
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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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