Judul: Analisis Kinerja Ekspor Ubi Kayu (Cassava) Indonesia ke Negara tujuan Ekspor
Abstrak: Indonesia merupakan tiga besar negara pengekspor ubi kayu di dunia yang memberikan peluang bagi Indonesia untuk menguasai pangsa pasar dunia. Tujuan dari penelitian ini adalah untuk menganalisis daya saing dan faktor–faktor yang memengaruhi permintaan ekspor ubi kayu Indonesia ke negara tujuan. Negara yang dianalisis adalah China, Korea, Amerika Serikat, Belanda, Brunei Darussalam, Singapura, Inggris, Australia, Malaysia, dan Hongkong pada periode 2001-2014. Metode yang digunakan dalam analisis adalah Revealed Comparative Advantage (RCA), Export Product Dynamic (EPD), dan gravity model. Hasil analisis RCA menunjukkan bahwa ubi kayu Indonesia berdaya saing di negara tujuan. Sedangkan hasil analisis EPD komoditas ubi kayu Indonesia berada pada posisi rising star untuk negara Australia, Amerika Serikat, Belanda, dan Singapura. Terdapat lima negara pada posisi falling star yaitu Brunei Darussalam, Korea, Inggris, Malaysia, Hongkong, dan pada posisi retreat adalah China. Pada hasil analisis gravity model menunjukkan bahwa kelima variabel berpengaruh secara signifikan terhadap permintaan ekspor ubi kayu Indonesia, yaitu jarak ekonomi, nilai tukar riil, GDP riil negara tujuan, populasi, dan harga ekspor riil.
Keyword: Daya saing, EPD, gravity model, RCA, ubi kayu

Judul: Analysis of Competitiveness and Factors Influencing Indonesian Sawn Timber Export
Abstrak: Indonesia dikenal sebagai negara produksi hasil hutan di dunia. Penelitian ini bertujuan menganalisis daya saing dan faktor-faktor yang memengaruhi ekspor kayu gergajian Indonesia. Metode penelitian untuk menganalisis daya saing adalah RCA, EPD, dan X-Model Potensial Export. Metode untuk menganalisis faktor-faktor yang memengaruhi ekspor kayu gergajian Indonesia adalah metode regresi data panel dengan time series 2013-2021 serta cross section enam negara tujuan ekspor. Hasil analisis RCA menunjukkan bahwa Indonesia memiliki daya saing komparatif di negara tujuan ekspor. Hasil EPD menunjukkan posisi pasar falling star di Korea Selatan, India dan Jepang sedangkan posisi rising star China, Bangladesh, dan Vietnam. Hasil X-Model menunjukkan komoditas kayu gergagjian memiliki potensi ekspansi pasar yang potensial di China, dan Vietnam sedangkan kurang potensial Jepang, India dan Korea Selatan serta posisi optimis ditempati Bangladesh. Hasil analisis regresi data panel menunjukkan GDP riil negara tujuan berpengaruh positif terhadap volume ekspor kayu gergajian Indonesia. Sedangkan nilai tukar, harga ekspor, jarak ekonomi dan populasi berpengaruh negatif terhadap volume ekspor kayu gergajian Indonesia., Indonesia is know as the largest forest product producing country in the world. This study aims to analyze competitiveness and the factors that influence Indonesia exports of sawn timber. Research methods to analyze competitiveness are RCA, EPD, and X-Model Potential Export the method for analyzing the factors influencing Indonesian sawn timber export is the panel data regression method with the 2013-2021 time series and cross sections of six export destination countries. The result of the RCA analysis show that Indonesia has comparative competitiveness in export destination country. The EPD result show the market positions of falling stars in South Korea and Japan while the positions of rising stars are China, Bangladesh, Vietnam and India. The result of the X-Model show that the sawn timber commodity has potential for market expansion in China, Vietnam, and India, while Japan and South Korea have less potential and Bangladesh occupy an optimistic position. The result of the panel data regression analysis show that the real GDP of the destination country has a positive effect on the export volume of Indonesia sawn timber. Meanwhile the exchange rate, export price, economic distance and population have a negative effect on the export volume of Indonesia sawn timber.
Keyword: EPD, Regresi Data Panel, RCA, X-Model, Kayu Gergajian

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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