Judul: Analysis of Trade Specialization and The Impact  of Non-Tariff Measures (NTM) on Indonesian Ginger Export to the Main Export  Destinations
Abstrak: Jahe merupakan komoditas andalan ekspor biofarmaka Indonesia tetapi kinerja ekspor jahe Indonesia justru mengalami penurunan selama beberapa tahun terakhir. Bahkan pada tahun 2019, Indonesia tercatat memiliki neraca perdagangan yang negatif dan menjadi negara pengimpor jahe. Penurunan ekspor jahe ini diduga disebabkan oleh ketidakmampuan produk untuk memenuhi persyaratan non-tariff measures (NTM) khususnya dalam bentuk sanitary and phytosanitary (SPS) dan technical barriers to trade (TBT) dari negara tujuan. Oleh karena itu, penelitian ini bertujuan untuk menganalisis spesialisasi perdagangan jahe Indonesia dan menganalisis dampak NTM terhadap ekspor jahe Indonesia ke negara-negara tujuan utama. Hasil dari Indeks Spesialisasi Perdagangan (ISP) menunjukkan bahwa Indonesia masih memiliki spesialisasi perdagangan sebagai eksportir jahe. Sementara hasil dari analisis regresi data panel dengan model gravity menunjukkan bahwa SPS berpengaruh positif dan TBT berpengaruh negatif terhadap ekspor jahe Indonesia ke negara-negara tujuan utama., Ginger is the main commodity of Indonesian herb export. However, Indonesia’s ginger export performance has declined over the last few years. Even in 2019, Indonesia had a negative trade balance and became a ginger importer country. The derivation of ginger export is thought to be caused by product inability to fulfil non-tariff measures (NTM) requirements especially for sanitary and phytosanitary (SPS) and technical barriers to trade (TBT). Therefore, this study aims to analyze the trade specialization of Indonesian ginger and analyze the impact of NTM on Indonesian ginger export to the main destination countries. The result of Indeks Spesialisasi Perdagangan (ISP) shows that Indonesia still have specialization in trading as a ginger exporter. Meanwhile the result of panel data regression analysis using gravity model shows that SPS has a positive effect and TBT has a negative effect on Indonesian ginger export to the main destination countries.
Keyword: Gravity Model, ISP, SPS, TBT

Judul: Faktor-Faktor yang Memengaruhi Volume Ekspor Jahe Indonesia
Abstrak: Indonesia merupakan salah satu produsen dan pengekspor jahe di pasar global. Permintaan jahe yang tinggi di pasar global selama periode 2013 sampai 2019 memberi peluang besar bagi Indonesia sebagai eksportir jahe. Namun, di periode yang sama ekspor jahe Indonesia justru menurun drastis. Penurunan volume ekspor jahe Indonesia dapat disebabkan oleh berbagai faktor. Penelitian ini bertujuan untuk menganalisis faktor-faktor yang memengaruhi volume ekspor jahe Indonesia selama periode 2013 sampai 2019 dengan cakupan penelitian meliputi 6 negara tujuan ekspor jahe Indonesia; Bangladesh, Malaysia, Singapura, Jepang, Amerika Serikat dan Belanda. Metode yang digunakan adalah analisis deskriptif melalui pendekatan inventory (coverage ratio) dan regresi data panel. Hasil estimasi menunjukkan bahwa nilai tukar dan populasi negara tujuan berpengaruh positif terhadap ekspor jahe, sedangkan GDP riil negara tujuan, harga ekspor jahe dan bentuk kebijakan non tarif Technical Barrier to Trade (TBT) berpengaruh negatif. Bentuk kebijakan non tarif Sanitary and Phytosanitary (SPS) tidak berpengaruh terhadap ekspor jahe., Indonesia is one of the producers and exporters of ginger in the global market. High demand for ginger in the global market during the period 2013-2019 provides opportunities for Indonesia as a ginger exporter. However, at the same period Indonesian ginger exports have declined significantly. There are several factors that affect the decline of Indonesian ginger export volume. This research aims to analyze the factors that affect the volume of Indonesian ginger exports during the period 2013-2019 with the scope of the study covering 6 export destinations of Indonesian ginger; Bangladesh, Malaysia, Singapore, Japan, the United States and the Netherlands. This study used a descriptive analysis method based on inventory approach (coverage ratio) and panel data regression. The result shows that the exchange rate and the population of the destination countries have a positive effect on ginger exports, while the real GDP of the destination countries, ginger export prices and the Technical Barrier to Trade (TBT) of non-tariff policies have a negative effect. The Sanitary and Phytosanitary (SPS) of non-tariff policies have no effect on ginger exports.
Keyword: Coverage Ratio, Export, Ginger, Panel Data

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: