Judul: Karakteristik Oseanografi dan Estimasi Indeks Kesehatan Laut di Kawasan Teluk Palabuhanratu dan Sekitarnya
Abstrak: Teluk Palabuhanratu dikenal sebagai salah satu daerah utama penangkapan ikan di perairan Selatan Jawa yang memiliki potensial perikanan pelagis dan sumber daya laut lainnya. Wilayah ini berpotensi terancam oleh kualitas air yang dapat mempengaruhi kesehatan lingkungan laut. Tujuan dari penelitian ini adalah mendeskripsikan karakteristik oseanografi secara spasio-temporal, variasi volume transpor, serta tren dan estimasi indeks kesehatan laut berdasarkan parameter oseanografi di Teluk Palabuhanratu. Dataset rataan harian dari keluaran model INDESO dan MARINE COPERNICUS (2008-2019) digunakan untuk penelitian ini. Data deret-waktu tersebut divalidasi dan dianalisis dengan metode Empirical Orthogonal Function (EOF), metode Power Spectral Density (PSD), serta estimasi tren dan indeks kesehatan laut. Hasil penelitian menunjukkan pola arus pada musim barat (musim timur) bergerak mendekati (menjauhi) teluk dengan pola sebaran suhu yang semakin rendah (tinggi) ke arah laut lepas sedangkan salinitas sebaliknya. Variasi suhu pada musim barat lebih tinggi (rendah) dibandingkan pada musim timur dan saat terjadi IOD negatif suhu lebih rendah. Struktur vertikal arus zonal pada musim barat (musim timur) arus permukaan dominan bergerak ke arah timur (ke arah barat), tetapi pada kedalaman 20-100 m pada musim barat (musim timur) terdapat arus yang bergerak ke arah barat (ke arah timur). Tren parameter selama 12 tahun menunjukan pola penurunan pada parameter suhu dan oksigen, sedangkan pada parameter lainnya mengalami kenaikan. Estimasi indeks kesehatan laut memiliki nilai 0.66 yang tergolong dalam kondisi cukup baik., The Palabuhanratu Bay is well known as one of the main fishing regions in the southern Java waters that has potential pelagic fisheries and other marine resources. This region may be potentially threatened by suitable water quality that may affects the health of the marine environment. The aim of this research is to describe the spatio-temporal oceanographic characteristics, transport volume variability, as well as trends and estimation of marine health indices based on oceanographic parameters in Palabuhanratu Bay. Daily averaged datasets from INDESO and MARINE COPERNICUS model outputs (2008-2019) were used for this study. The time-series data were validated and analyzed by Empirical Orthogonal Function (EOF) method, Power Spectral Density (PSD) method, and trend estimation and ocean health index. The results showed that the current pattern in the west season (east season) moves closer to (away from) the bay with a lower (higher) sea water temperature distribution pattern towards the open sea while salinity is the opposite. Variability of seawater temperature in the western season are higher (lower) than in the eastern season and during negative IOD temperatures are lower. The vertical structure of zonal currents in the west season (east season) dominant surface currents move eastward (westward), but at a depth of 20-100 m in the west season (east season) there are currents that move westward (eastward). The trend of parameters for 12 years shows a decreasing pattern in temperature and oxygen parameters, while other parameters have increased. The estimated ocean health index has a value of 0.66, which is classified as in fairly good condition
Keyword: Analisis data deret-waktu, dataset INDESO, indeks kesehatan laut, karakteristik oseanografi, Teluk Palabuhanratu

Judul: Oceanographic Characteristic, Trend Estimation and Ocean Health Index in Madura Strait
Abstrak: Selat Madura merupakan wilayah perairan yang banyak dimanfaatkan sebagai alur pelayaran, daerah penangkapan ikan, dan eksploitasi migas bumi. Kegiatan pemanfaatan tersebut berpengaruh pada kesehatan lingkungan laut. Tujuan dari penelitian ini adalah mendeskripsikan pola spasial dan variasi temporal dari beberapa parameter oseanografi, struktur vertikal arus, tren dan kondisi kesehatan laut berdasarkan parameter oseanografi yang diestimasi dari nilai IKL di Perairan Selat Madura. Data INDESO dan Marine Copernicus digunakan untuk penelitian dengan analisis data mencakup validasi, volume trasnport, EOF, CWT, tren, dan perhitungan IKL. Hasil penelitian menunjukkan siklus tahunan SPL laut berkisar 27,89 – 30,77 oC, salinitas berkisar 17,51 – 33,6 PSU, TPLberkisar 0,505 – 0,676 m, fosfat berkisar 0,00001 – 0,00978 mg/l, nitrat berkisar 0,00023 – 0,04225 mg/l , klorofil berkisar 0,107 – 1,196 mg/m3, dan DO berkisar 6,318 – 6,77 mg/l. Struktur vertikal arus zonal pada musim barat (musim timur), arus permukaan cenderung bergerak ke arah timur (ke arah barat), tetapi pada musim timur di kedalaman 6-36 m arus bergerak ke arah timur. Struktur vertikal arus meridional pada musim barat dan timur, arus cenderung bergerak ke utara. Tren 12 tahun menunjukkan pola kenaikan hanya pada parameter salinitas dan nitrat sedangkan pada parameter lain mengalami penurunan. Estimasi nilai IKL berkisar 0,63 sehingga Selat Madura tergolong dalam kondisi yang sedang., Madura Strait is a water area that is widely used as a shipping channel, fishing area, and oil and gas exploitation. These utilization activities affect the health of the marine environment. The study aimed to describe the spatial patterns and temporal variations of several oceanographic parameters, the vertical structure of currents, trends, and ocean health conditions based on oceanographic parameters estimated from the OHI value in the Madura Strait Waters. INDESO and Marine Copernicus data were used for the study with data analysis including validation, transport volume, EOF, CWT, trend, and calculation of OHI. The results showed the annual cycle of ocean SST ranged from 27,89 – 30,77 oC, salinity ranged from 17,51 – 33,6 PSU, SSH ranged from 0,505 – 0,676 m, phosphate ranged from 0,00001 – 0,00978 mg/l, nitrate ranged from 0,00023 – 0,04225 mg/l, chlorophyll-a ranged from 0,107 – 1,196 mg/m3, and DO ranged from 6,318 – 6,77 mg/l. In the vertical structure of zonal currents during the west monsoon (east monsoon), surface currents tended to move eastward (westward), but during the east monsoon at depths of 6-36 m, the currents move eastward. The vertical structure of meridional currents during the west and east monsoon showed that currents tended to move northward. The 12-year trend showed an increasing pattern only in the salinity and nitrate parameters while other parameters decreased. The estimated OHI value was around 0,63, so the Madura Strait was classified as being in a fair condition.
Keyword: Indeks Kesehatan Laut, INDESO, Oseanografi, Selat Madura, Tren

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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