Judul: Volatilitas dan Pembentukan Harga Bawang Putih di Indonesia
Abstrak: Allium sativum or garlic is one of the agricultural commodities that has a high level of consumption in Indonesia. However, domestic demand for garlic depends on imported garlic products, causing uncertainty in domestic garlic prices. Uncertainty in the price of garlic in Indonesia is related to how high the increase or decrease in the price of garlic is, or called by price volatility. It is also will get worse with the Covid-19 pandemic because the main import destination for Indonesian garlic is China. The aim of this study was to analyze the volatility of Indonesian garlic prices before and during the Covid-19 outbreak. The data used is the consumer price of Indonesian garlic and is analyzed using the ARCH-GARCH analysis. The results of this study are that volatility occurred both before and during Covid-19. The highest volatility occurred in July 2019 which was allegedly the result of a surge in garlic imports from China. During the Covid-19 pandemic, the price of garlic also experienced price volatility. The volatility was due to the panic buying impact of Covid-19. Covid-19 at the beginning of 2020 caused distributors to reduce the supply of garlic to the market, because it was feared that it would make it difficult for distributors to import garlic.
Keyword: volatilitas, harga, bawang putih, ecm, arch-garch

Judul: The Impact of Policies and Determinants of Indonesian Garlic Imports from China
Abstrak: Bawang putih merupakan komoditas hortikultura yang ditargetkan pemerintah untuk swasembada di tahun 2021 untuk memenuhi permintaan bawang putih nasional. Akan tetapi, produksi bawang putih domestik masih belum mampu memenuhi permintaan tersebut. Dengan demikian, sebagian besar kebutuhan akan bawang putih dalam negeri dipenuhi dengan melakukan impor bawang putih dari negara produsen bawang putih. Cina merupakan produsen bawang putih terbesar di dunia yang juga merupakan negara pengekspor utama bawang putih ke Indonesia. Penelitian ini bertujuan menganalisis pengaruh kebijakan dan faktor penentu impor bawang putih Indonesia dari Cina tahun 1996 hingga 2019 menggunakan analisis regresi linier berganda dengan metode Ordinary Least Square (OLS). Berdasarkan hasil estimasi, variabel yang berpengaruh signifikan terhadap volume impor bawang putih dari Cina adalah harga bawang putih impor, harga bawang merah domestik, populasi Indonesia, dan kebijakan penghapusan tarif. Sedangkan nilai tukar riil dan kebijakan RIPH tidak berpengaruh signifikan terhadap volume impor bawang putih dari Cina., Garlic is a horticultural commodity targeted by the government for self-sufficiency in 2021 to fulfill the national demand. However, garlic production is still unable to meet the domestic demand. Thus, most of the domestic demand for garlic has been fulfilled by importing garlic from garlic producing countries. China is the largest producer of garlic in the world and is the main exporter of garlic to Indonesia. This research aims to analyze the policies impact and determinants of Indonesian garlic imports from China since 1996 to 2019 using multiple linear regression analysis with the Ordinary Least Square (OLS) method. Based on the estimation results, the variables that significantly affect the volume of imported garlic from China are the price of imported garlic, the price of domestic shallots, the population of Indonesia, and tariff elimination policy. Meanwhile, the real exchange rate and the RIPH policy did not significantly affect the import volume of garlic from China.
Keyword: China, horticultural, Ordinary Least Square

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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