Judul: Strategy for Development of Superior Commodity  Based Capture Fisheries System at Logending Coastal Fishing Port Kebumen Central Java
Abstrak: Hasil tangkapan ikan di PPP Logending periode tahun 2016–2019 berfluktuasi, sementara itu nilai produksi cenderung naik. Hal ini disebabkan oleh beberapa faktor, seperti pendangkalan kolam pelabuhan dan faktor cuaca. Kondisi ini menjadi fokus kajian dengan menetapkan kebijakan yang tepat untuk pengembangannya berbasis komoditas ikan unggulan. Tujuan penelitian adalah menentukan sumber daya ikan komoditas unggulan, mendeskripsikan kondisi sistem perikanan tangkap, serta merumuskan prioritas kebijakan dalam strategi pengembangan perikanan tangkap komoditas unggulan yang berbasis di PPP Logending. Penelitian menggunakan pendekatan sistem. Pengambilan data lapang menggunakan metode survei. Analisis data meliputi aspek biologi, teknis, finansial, dan sosial, serta analisis hierarki proses. Hasil penelitian menunjukkan sumber daya ikan unggulan adalah ikan layur, bawal putih, dan tenggiri dengan nilai skor masing-masing (3,76; 2,25; dan 1,47). Musim penangkapan ikan terjadi pada bulan Agustus–November. Alat tangkap dominan gillnet dan trammel net dengan kapal berukuran 1–3 GT. Alternatif prioritas strategi pengembangan perikanan tangkap berbasis komoditas unggulan di PPP Logending adalah kualitas sumber daya manusia dengan nilai rasio kepentingan 0,620., The catch of fish at PPP Logending for the period 2016–2019 fluctuates, while the value of production tends to increase. This is due to several factors, such as siltation of the harbor pond and weather factors. This condition became the focus of the study by determining the right policy for its development based on superior fish commodities. The objectives of the study were to determine the fish resources of superior commodities, describe the condition of the capture fisheries system, and formulate policy priorities in the development strategy of superior commodity capture fisheries based at PPP Logending. The research used a system approach. Field data collection using survey method. Data analysis included biological, technical, financial, and social aspects, as well as hierarchical process analysis. The results showed that the leading fish resources were hairtail fish, white pomfret, and mackerel with respective score values (3.76; 2.25; and 1.47). The fishing season occurs in August–November. The dominant fishing gear is gillnet and trammel net with vessels of 1–3 GT. Alternative priority strategy for the development of capture fisheries based on superior commodities at PPP Logending is the quality of human resources with an importance ratio value of 0.620.
Keyword: analytical hierarchy process, development strategy, Kebumen, PPP Logending, superior commodities

Judul: Catching productivity and biotechnical economic analysis of Danish Seine Net Fishing Units at Palabuhanratu Fishing Port
Abstrak: Volume produksi ikan tongkol di PPN Palabuhanratu tahun 2017 sampai 2021 menunjukkan trend menurun. Salah satu alat tangkap yang menangkap tongkol adalah payang. Penelitian ini bertujuan menganalisis produktivitas penangkapan dan bioteknik ekonomi unit penangkapan payang di PPN Palabuhanratu. Analisis yang dilakukan yaitu CPUE, komposisi hasil tangkapan, korelasi Pearson, dan analisis ekonomi. Penelitian dilakukan di PPN Palabuhanratu, pada bulan April sampai Mei 2022, menggunakan metode observasi dan wawancara. Produktivitas unit penangkapan payang mengalami fluktuasi dan pada tahun 2021 terjadi penurunan sebesar 50% tetapi trend yang dihasilkan masih stabil. komposisi hasil tangkapan payang di antaranya cakalang, eteman, peperek, tongkol lisong, tongkol banjar, dan tongkol abu-abu. Terdapat beberapa jenis ikan dengan volume produksi yang rendah tetapi bernilai ekonomis di antaranya ikan selar bentong, kuwe, dan gulamah. Faktor teknis yang mempengaruhi produksi kegiatan penangkapan adalah lama setting dan hauling, jumlah ABK mempengaruhi waktu yang dibutuhkan untuk melakukan setting dan hauling. Analisis ekonomi dari kelayakan usaha diperoleh keuntungan sebesar Rp79.928.095,00, PP selama tiga tahun delapan bulan, dan ROI sebesar 20,88%, kelayakan investasi menunjukkan nilai NPV sebesar Rp230.766.053,00, nilai IRR sebesar 24,1%, dan nilai Net B/C 1,786 sehingga usaha menguntungkan dan investasi layak dilakukan., The volume of mackerel tuna production at Palabuhanratu Fishing Port in 2017 to 2021 shows declining trend. One fishing gear that catches mackerel tuna is danish seine net. This study aims to analyze catching productivity and biotechnical economic of danish seine net fishing unit at Palabuhanratu. Analysis carried out is CPUE, catch composition, Pearson correlation, and economic analysis. The research was conducted at Palabuhanratu Fishing Port, in April to May 2022, using observation and interview methods. The productivity of danish seine net fluctuates, in 2021 there will be a 50% decrease in productivity, but resulting trend is still stable. The composition of danish seine net catch included skipjack tuna, moonfish, ponyfish, bullet tuna, black skipjack, and longtail tuna. Fish with low production but high economic value include bigeye scad, giant trevally, and leaftail croaker. Technical factors that affect the production of fishing activities are the length of setting and hauling, number of crews affects time needed to setting and hauling. Economic analysis of business feasibility obtained profit Rp79.928.095.00, PP for three years and eight months, and ROI 20,88%, investment feasibility shows NPV value Rp230.766053.00, IRR value 24,1%, and Net B/C value is 1,786, so that business is profitable and investment is feasible.
Keyword: biotechnical economic analysis, catching productivity, danish seine net, mackerel tuna

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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