Judul: Competitiveness of Indonesian Cocoa  Beans and Processed Cocoa Products in the International Market
Abstrak: Kakao memberikan kontribusi pendapatan nasional ketiga tertinggi setelah karet dan kelapa sawit. Sebagian besar kakao Indonesia diekspor dalam bentuk biji. Namun, setelah adanya kebijakan bea keluar terhadap biji kakao terjadi perubahan struktur ekspor yang semula didominasi biji bergeser menjadi produk olahan. Penelitian ini bertujuan untuk mengevaluasi perkembangan dan struktur ekspor kakao setelah adanya kebijakan bea keluar dan menganalisis daya saing biji kakao Indonesia dan beberapa produk olahannya. Metode yang digunakan adalah indeks Revealed Comparative Advantage (RCA), Indeks Spesialisasi Perdagangan (ISP), dan Export Product Dynamics (EPD). Hasil penelitian menunjukkan bahwa daya saing biji kakao Indonesia setelah adanya kebijakan bea keluar diukur dengan metode RCA mengalami penurunan signifikan bahkan pada tahun 2016 sampai 2018 nilai RCA biji kakao Indonesia kurang dari satu yang artinya biji kakao Indonesia tidak memiliki keunggulan komparatif. Sedangkan daya saing produk olahan kakao Indonesia kecuali coklat mengalami peningkatan, nilai RCA pasta kakao, lemak kakao, dan bubuk kakao menunjukkan ketiga produk tersebut memiliki keunggulan komparatif., Cocoa provides the third highest contribution to national income after rubber and palm oil. Most of Indonesia's cocoa is exported in the form of beans. However, after the export tax policy for cocoa beans, there was a change in the export structure, which was originally dominated by cocoa beans, shifted to processed products. This study aims to evaluate the development and structure of cocoa exports after the export tax policy and to analyze the competitiveness of Indonesian cocoa beans and some of their processed products. The methods used are Revealed Comparative Advantage (RCA), Trade Specialization Index (ISP), and Export Product Dynamics (EPD). The results showed that the competitiveness of Indonesian cocoa beans after the export tax policy measured by the RCA method decreased significantly, even 2016 to 2018 the RCA value of Indonesian cocoa beans was less than one, meaning that Indonesian’s cocoa beans did not have a comparative advantage. While the competitiveness of processed Indonesian cocoa products except chocolate has increased, the RCA value of cocoa paste, cocoa butter, and cocoa powder shows that these three products have a comparative advantage.
Keyword: Cocoa Beans, Cocoa Processed Products, Exports, RCA

Judul: Analisis Daya Saing Kakao Olahan Indonesia di Negara Tujuan Ekspor Utama
Abstrak: Indonesia merupakan salah satu negara produsen kakao terbesar di dunia sehingga memiliki potensi yang baik dalam meningkatkan ekspor kakao olahan. Penelitian ini bertujuan untuk (1) menganalisis keunggulan komparatif kakao olahan Indonesia di negara tujuan ekspor utama, (2) menganalisis keunggulan kompetitif kakao olahan Indonesia di negara tujuan ekspor utama, dan (3) menganalisis faktor-faktor yang mempengaruhi ekspor kakao olahan Indonesia di negara tujuan ekspor utama. Metode analisis yang digunakan adalah Revealed Comparative Advantage (RCA), Export Product Dynamic (EPD), Acceleration Ratio (AR), dan Gravity Model. Analisis RCA menunjukkan bahwa kakao olahan Indonesia berdaya saing kuat di negara tujuan ekspor utama. Analisis EPD menunjukkan bahwa posisi pasar ekspor kakao olahan Indonesia berada pada posisi Rising Star dan Lost Opportunity. Analisis AR menunjukkan bahwa Indonesia mampu merebut pasar kakao olahan di negara tujuan ekspor utama. Faktor-faktor yang mempengaruhi ekspor lemak kakao adalah GDP riil per kapita negara tujuan, GDP riil per kapita Indonesia, nilai tukar riil negara tujuan terhadap dollar AS, sedangkan untuk bubuk kakao adalah GDP riil per kapita negara tujuan, GDP riil per kapita Indonesia, nilai tukar riil negara tujuan terhadap dollar AS, dan jarak ekonomi., Indonesia is one of the biggest cocoa producers in the world so it has a great potential to increase processed cocoa export. This research aims to: (1) analyze the comparative advantage of Indonesian processed cocoa in the main export destination countries, (2) analyze the competitive advantage of Indonesian processed cocoa in the main export destination countries, and (3) analyze the factors that affect the export of Indonesian processed cocoa in the main export destination countries. The analytical methods are Revealed Comparative Advantage (RCA), Export Product Dynamic (EPD), Acceleration Ratio (AR), and Gravity Model. RCA analysis showed that Indonesian processed cocoa has strong competitiveness in the destination countries. EPD analysis showed that the market position of the Indonesian processed cocoa export is either Rising Star or Lost Opportunity. AR analysis showed that Indonesia has able to seize the export market for all processed cocoa in all destination countries. Variables that affect the export of cocoa butter are the real GDP per capita of the destination countries, the real GDP per capita of Indonesia, the real exchange rate, while for cocoa powder are the real GDP per capita of the destination countries, the real GDP per capita of Indonesia, the real exchange rate, and the economic distance.
Keyword: Acceleration Ratio (AR), export duty, Export Product Dynamic (EPD), Gravity Model, Revealed Comparative Advantage (RCA)

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: