Judul: Coastal Circulation and Trajectory Analysis of Water Particles Related to Oil Spill in the North Coastal Waters of Karawang
Abstrak: Perairan Pantai Utara Karawang adalah bagian dari Laut Jawa yang dipengaruhi oleh variabilitas muson. Sehingga interaksi antara muson dengan sirkulasi permukaan laut perairan Karawang diduga dapat mempengaruhi pola distribusi pencemar, terutama berkaitan dengan kejadian tumpahan minyak di perairan Karawang. Tujuan penelitian ini membangun model sirkulasi menggunakan CROCO, serta menganalisis pola sirkulasi dan trajektori partikel massa air sebagai tahap awal analisis tumpahan minyak. Penentuan titik keluaran tumpahan minyak menggunakan citra Sentinel-1A. Metode analisis data dengan Diagram Taylor, deret-waktu, klimatologi, sirkulasi permukaan laut, serta analisis trajektori menggunakan Ichthyop. Model yang dibangun dengan resolusi 1/96º (±1.159 km), dengan validasi SST, SSH, dan komponen arus (zonal dan meridional) menunjukkan korelasi yang tinggi (0.86, 0.87, 0.96, 0.91). Hasil penelitian menunjukkan tren kenaikan suhu terjadi di musim peralihan 1 dan 2 dan terendah di muson timur. Tren salinitas meningkat dari Februari-Oktober dan menurun dari November-Februari. Selama muson barat, pola sirkulasi air laut bergerak dari barat menuju timur dan mulai berbalik arah pada bulan April. Memasuki muson timur pola sirkulasi bergerak dari timur menuju barat. Dominansi arah arus ini juga ditemukan di musim peralihan 2. Hasil model CROCO digunakan untuk analisis trajektori partikel massa air dengan Ichthyop menunjukkan pergerakan partikel yang sesuai dengan arus yang terjadi pada bulan Juli, dimana secara keseluruhan pergerakan partikel didominasi pergerakan dari arah timur menuju barat dan mengikuti kontur topografi Pantai Utara Jawa., The waters of the North Coast of Karawang are part of the Java Sea which is influenced by monsoon variability. Thus, the interaction between monsoons and sea surface circulation in Karawang waters is expected to affect the distribution pattern of polluted materials, especially related to the oil spill event in Karawang waters. The objective of this study is to build circulation model using CROCO and analyze the circulation pattern and water mass trajectory as the preliminary stage of oil spill analysis. The released point of the oil spill is determined using Sentinel-1A imagery. Data analysis method using Taylor Diagrams, time series, climatology, sea surface circulation, and trajectory analysis using Ichthyop. This model used 1/96º resolution (±1.159 km), where SST, SSH, and current components validation showed high correlation (0.86, 0.87, 0.96, 0.91). The results showed that the trend of temperature is increased during monsoon breaks 1 and 2 while the lowest occurred in the southeast monsoon. The trend of salinity increased from February-October and decreased from November-February. During the northwest monsoon, the seawater circulation pattern moves from west to east and begins to reverse in April. Entering the southeast monsoon, the circulation pattern moves from east to west. The results of the CROCO model used for the analysis of water mass particle trajectories with Ichthyop showed that the particle movement corresponds to the current that occurred in July, where overall particle movement is dominated by current movement from east to west and through contours of the north coast of Java.
Keyword: the Java Sea, Ocean circulation, CROCO, Ichthyop, Trajectory, Oil spill

Judul: Spreading Detection of Oil Spill Based on Satellite Data at Karawang Waters
Abstrak: Tumpahan minyak akibat kebocoran minyak di sekitar anjungan lepas pantai di perairan Karawang telah menimbulkan dampak negatif bagi sumberdaya alam, lingkungan, dan ekonomi. Penelitian ini bertujuan mendeteksi sebaran tumpahan minyak di perairan Karawang, Laut Jawa mengunakan citra satelit optik (Aqua-MODIS, Landsat 8, dan Sentinel 2B) berdasarkan perbedaan nilai spektral remote sensing reflectance (Rrs) kanal RGB dan penerapan algoritma (oil spill index, fluorescence index, dan NDVI). Nilai spektral Rrs di daerah yang terdapat tumpahan minyak lebih tinggi dibandingkan dengan lokasi yang tidak terkena tumpahan minyak karena lapisan minyak memiliki indeks bias yang tinggi sehingga merefleksikan radiasi lebih besar dibandingkan permukaan air laut bersih. Secara umum, algoritma NDVI menghasilkan peta sebaran tumpahan minyak yang terbaik. Berdasarkan visualisasi true color pada satelit Aqua-MODIS tanggal 13 Juli 2019 dan 15 Juli 2019, satelit Landsat-8 tanggal 25 Juli 2019, Sentinel 2B tanggal 28 Agustus 2019, estimasi luas sebaran minyak berturut-turut adalah 21,9396 km², 35,0338 km², 23,4737 km², dan 10,5114 km². Minyak menyebar ke arah Barat–Barat Laut pada jangka waktu Juli–Agustus 2019., Oil spills around an oil offshore platform in the Karawang waters had a negative effect on natural resources, environment, and economic. The main purposes of this research were to detect oil spills in Karawang waters, Java Sea by using an optical satellite images (Aqua-MODIS, Landsat 8, and Sentinel 2) based on differences in remote sensing reflectance (Rrs) value in RGB bands and the application of several algorithms (oil spill index, fluorescence index, and NDVI) on images processing. Rrs values were higher where oil spills were detected, because the oil layers had a high refractive index causing the oil surface to reflect radiation greater than clean water surface. In general, the NDVI algorithm produced the best map of the distribution of oil spills. Based on true color visualization on the Aqua-MODIS satellite on 13 July 2019 and 15 July 2019, Landsat-8 satellite on 25 July 2019, Sentinel 2B on 28 August 2019, the estimated oil spreading area were 21.9396 km², 35.0338 km², 23.4737 km², and 10.5114 km², respectively. The oil spills spreaded from East to Westward–Northwest on July–August 2019.
Keyword: fluorescence index, NDVI, oil spill, remote sensing reflectance

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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