Judul: Identifikasi Pola Pergerakan Harga Beras Melalui Dekomposisi Deret Waktu Secara Ensemble
Abstrak: The price of rice is one of the important indicator to determine the availability of rice. Ensemble Empirical Mode Decomposition (Ensemble EMD) is an alternative approach to analyze rice price fluctuation behavior through the process decomposition into several intrinsic mode functions (IMFs) and the residual. The EMD could be applied to a dataset eventhough that the data are nonlinear and nonstationary so it can work with the characteristics of unstable rice prices between seasons and years. The concept of ensemble is needed to optimalize the characteristic scale of the IMF by adding a series of white noise in the data. This research was carried out on the identification of the time series pattern of monthly and weekly rice price in Jakarta using Ensemble EMD. Our Ensemble EMD approach resulted three IMFs which have large contribution to volatility of monthly rice price. Those are IMFs whose mean periods of 1.1, 2.8 and 5.6 years respectively. Meanwhile, from the weekly dataset, Ensemble EMD revealed three high contribution IMFs, whose mean period of 0.5, 1.0, and 3.4 years. Trend component contributes dominantly to the price level change. It could be seen by its contribution as long as 92.40% for monthly data and 96.34% for weekly data. Furthermore, the reconstruction of fine-to-coarse for weekly price data shows that all IMFs produced by decomposition weekly rice price are included in the high frequency component. It indicates that the imbalance of supply and demand market and the weather factor still affect the stability of rice prices in Jakarta.
Keyword: rice prices, ensemble, empirical mode decomposition

Judul: Analysis of Rice Market Integration in Indonesia.
Abstrak: Beras merupakan komoditas pangan strategis dan termasuk barang inelastis yang memiliki permintaan tinggi di sepanjang tahun. Namun produksi yang bergantung pada musim tanam mengakibatkan harga komoditas beras menjadi tidak stabil sehingga terjadi selisih harga yang besar antara harga di tingkat petani produsen dan harga di tingkat konsumen akhir. Penelitian ini bertujuan untuk mengetahui pola pergerakan harga gabah-beras dan menganalisis integrasi pada pasar beras Indonesia. Analisis integrasi dilakukan dengan Vector Error Correction Model (VECM). Hasil analisis menunjukkan bahwa harga gabah lebih fluktuatif dibandingkan dengan harga beras eceran maupun beras grosir dan kebijakan pemerintah mengatur harga beras efektif menstabilkan harga gabah bulanan. Hasil analisis VECM menunjukkan bahwa antara pasar produsen dan pasar grosir tidak terjadi integrasi jangka panjang dan terintegrasi dalam jangka pendek. Antara pasar produsen dan pasar eceran tidak terintegrasi dalam jangka panjang maupun jangka pendek. Antara pasar grosir dan pasar konsumen terintegrasi baik dalam jangka panjang maupun jangka pendek., Rice is a strategic food commodity and an inelastic goods that have high demand throughout the year. However, rice production that depends on the growing season causes the price of rice to become unstable, resulting in a large price difference between the farmers price and the consumer price. This study aims to determine the pattern of grain-rice price movements and analyze the integration that occurs in Indonesian rice markets. Integration analysis was analyzed using Vector Error Correction Model (VECM). The analysis showed that grain price was more volatile than the retail and wholesale rice prices and the government's policy to regulate rice prices is effective in stabilizing monthly grain prices. The analysis result showed that the market integration in producers markets and wholesale market are not integrated in the long-term, but they are integrated in the short-term. There no integration between the producers and consumers in long or short-term. The wholesale markets and retail markets are integrated well in the long-term and short-term.
Keyword: rice price, market integration, VECM

Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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