Judul: Trends and Patterns of Ocean Health Index Fluctuations Based on Physical Oceanographic Parameters in the Cendrawasih Bay National Park Area
Abstrak: Taman Nasional Teluk Cendrawasih (TNTC) merupakan kawasan perairan laut terbesar di Papua dan salah satu Taman Nasional terbesar di Indonesia. Kawasan ini diketahui memiliki biodiversitas hayati laut yang tinggi, sehingga perlu dilakukan penilaian dan pemantauan kondisi lingkungan laut secara sinambung melalui kuantifikasi Indeks Kesehatan Laut (IKL). Indeks Kesehatan Laut (IKL) atau Ocean Health Index (OHI) merupakan kerangka penilaian terpadu pertama yang menggabungkan unsur penting biologi, fisik, ekonomi, dan sosial dari kesehatan laut secara ilmiah. IKL dapat digunakan sebagai alat untuk menilai dan memantau kesehatan dan manfaat laut secara keseluruhan. Tujuan dari penelitian ini adalah untuk mendeskripsikan karakteristik dan variabilitas, serta tren dan estimasi Indeks Kesehatan Laut (IKL) di perairan Teluk Cendrawasih dengan fokus hanya pada parameter oseanografi fisik. Dataset selama 11 tahun (2008-2018), keluaran simulasi model laut INDESO dengan variabel komponen arus zonal, meridional, salinitas, suhu, dan tinggi muka laut (TPL) dianalisis periodisitas, tren dan nilai IKL-nya. Hasil penelitian diperoleh bahwa variabilitas parameter oseanografi fisik di TNTC berfluktuasi pada skala-waktu tahunan dan antar- tahunan. Estimasi rerata volume transpor di sisi utara teluk adalah -0.0817 Sv (ke arah selatan). Dalam rentang waktu 11 tahun, tren suhu, kedalaman isotherm 27°C, dan TPL mengalami penurunan, tetapi tren salinitas mengalami kenaikan. Estimasi IKL dari 3 parameter oseanografi fisik (suhu, salinitas, TPL) menunjukkan bahwa perairan TNTC termasuk ke dalam kategori sedang (fair) dengan nilai IKL sekitar 0.90., Cendrawasih Bay National Park is the largest marine area in Papua and one of the largest National Parks in Indonesia. This area is known to have high marine biodiversity, so it is necessary to continuously assess and monitor the condition of the marine environment through the quantification of the Ocean Health Index (OHI). The Ocean Health Index (OHI) is the first integrated assessment framework that combines the scientifically important biological, physical, economic and social elements of ocean health. OHI can be used as a tool to assess and monitor the overall health and benefits of the ocean. The purpose of this study is to describe the characteristics and variability, as well as trends and estimates of the Ocean Health Index (OHI) in the waters of Cendrawasih Bay with a focus only on physical oceanographic parameters. The dataset for 11 years (2008-2018), the output of the INDESO marine model simulation with the component variables of zonal current, meridional current, salinity, temperature, and sea surface height (SSH) were analyzed for periodicity, trends and OHI values. The results showed that the variability of physical oceanographic parameters in Cendrawasih Bay waters fluctuates on an annual and inter-annual time-scale. The estimated mean transport volume on the north side of the bay is -0.0817 Sv (to the south). In a span of 11 years, the trend of temperature, depth isotherm 27°C, and SSH has decreased, but the trend of salinity has increased. OHI estimation using 3 physical oceanographic parameters (temperature, salinity, SSH) shows that the Cendrawasih Bay waters are in the fair category with an OHI value of around 0.90.
Keyword: Dataset INDESO, Indeks Kesehatan Laut (IKL), Teluk Cendrawasih, Tren, Variabilitas

Judul: Variation of seasonal, Trend and Ocean Health Index based on Oceanographic Parameter in the Natuna Sea
Abstrak: Laut Natuna merupakan salah satu laut Indonesia yang berbatasan langsung dengan Laut Cina Selatan dan Laut Jawa. Laut ini memiliki kelimpahan sumberdaya perikanan, migas, dan tambang. Sehingga dapat menimbulkan fenomena serta masalah terhadap kondisi kesehatan perairan. Tujuan dari penelitian ini adalah mengetahui variasi musiman, variabilitas, tren, serta indeks kesehatan Laut Natuna. Data model INDESO dengan resolusi 1/12° dan Marine Copernicus digunakan untuk studi dengan analisis data mencakup validasi, volume transport, karakteristik musiman oseanografi, variabilitas, tren, dan perhitungan Indeks Kesehatan Laut (IKL). Hasil penelitian menggambarkan validasi data model dengan satelit memiliki korelasi yang tinggi yaitu 0,94 (suhu permukaan laut/SPL), 0,70 (arus zonal), dan 0,95 (arus meridional). Siklus musiman SPL di Laut Natuna berkisar 27,21 sampai 32,00 °C, salinitas berkisar 32,00 sampai 34,00 PSU, oksigen terlarut (DO) berkisar 5,465 sampai 7,112 mg/L, dan nitrat berkisar 0,0005 sampai 0,0780 mg/L. Analisis Transformasi Wavelet Kontinu menunjukkan variabilitas parameter yaitu Semi Annual Variability (SAV), Intra Seasonal Variability (ISV), Annual Variability (AV), dan Inter Annual Variability (IAV). Tren per tahun menunjukkan nilai -0,05 °C (SPL), 0,07 PSU (salinitas), -0,002 mg/L (DO), dan -0,0002 mg/L (nitrat). Nilai IKLNatuna berkisar 71,54 dan tergolong dalam kategori cukup baik., The Natuna Sea is one of Indonesian seas that are contiguous with the South China Sea and the Java Sea. This sea has abundant resources of fish, oil and gas, and mines. Thus, the marine health in this sea is prone to problems. The aim of this study was to find out the seasonal variation, variability, trend, and Ocean Health Index of the Natuna Sea. INDESO data model with the resolution of 1/12° and Marine Corpernicus were used in this study with the scope of analysis covering validation, volume transport, seasonal oceanographic characteristic, variability, trend, and Ocean Health Index calculation. The results portray that the data model validation with the satellite shows a high degree of correlation which are 0,94 (sea surface temperature), 0,70 (zonal current), and 0,95 (meridional current). Seasonal SPL cycle in the Natuna Sea ranges from 27,21 °C to 32,00 °C, salinity ranges from 32,00 to 34,00 PSU, dissolved oxygen (DO) ranges between 5,465 and 7,112 mg/L, nitrate ranges from 0,0005 to 0,0780mg/L. Continuous Wavelet Transform analysis showed parameter variabilities which are Semi Annual Variability (SAV), Intra Seasonal Variability (ISV), Annual Variability (AV), and Inter Annual Variability (IAV). Annual parameter trend shows the value of -0,05°C (SPL), 0,07 PSU (salinity), -0,002 mg/L (DO), and -0,0002 mg/L (nitrate). The Natuna Sea’s IKL values around 71,54 and is considered good enough.
Keyword: IKL, INDESO, Natuna Sea, Trend, Variability

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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