Judul: Evaluasi Atribut Produktivitas Ikan Sidat (Anguilla bicolor bicolor) di Sungai Cimandiri, Pelabuhanratu, Kabupaten Sukabumi, Jawa Barat
Abstrak: Purpose the research is to evaluate NOAA methods and attribute productivity of anguillid eel needed to suppose sustainable potention anguillid eel. All arrested the anguillid eel pigmented in Cimandiri Rivers observed growth parameters, reproduction, and mortality rate. Sample anguillid eel in gather for research in Juni to December totaled 209 tail. An abundance of anguillid eel increase the same time as the rainy season. Evaluation the attribute of productivity indicate that score made by NOAA not comforming if adapted to anguillid eel and the result 3 score krom NOAA and 1,375-2,5 to be score modification. Based on the result obtained, which made The score NOAA can not be adapted to the anguillid eel. Fish difference and environment can to affect productivity.
Keyword: Cimandiri River, Anguillid eel, Evaluate attribute productivity

Judul: Analisis Sumberdaya dan Faktor-faktor Pengelolaan Perikanan Sidat (Anguilla spp.) di Muara Sungai Cibuni, Kabupaten Sukabumi
Abstrak: Indonesia memiliki kelimpahan sidat baik dalam ukuran benih maupun ukuran konsumsi yang melimpah, namun belum dimanfaatkan dengan baik. Penelitian ini dilaksanakan pada bulan Februari sampai bulan Juni 2021. Tujuan penelitian adalah mengidentifikasi dan menganalisis faktor pengelolaan perikanan sidat di muara Sungai Cibuni, Kabupaten Sukabumi. Manfaat dari penelitian ini adalah menyajikan informasi terkait faktor sosial-ekologi perikanan sidat (glass eel) yang dapat menjadi acuan dalam pengelolaan sumberdaya dan perikanan sidat di muara Cibuni, Kabupaten Sukabumi. Pengambilan sampel glass eel dilakukan selama lima hari pada fase bulan gelap setiap bulannya. Muara Sungai Cibuni memiliki kualitas perairan yang baik dengan kisaran sesuai baku mutu, tipologi muara juga mendukung ruaya sidat. Muara Sungai Cibuni memiliki tiga jenis sidat yaitu Anguilla bicolor bicolor, Anguilla marmorata dan Anguilla nebulosa nebulosa. Anguilla bicolor bicolor mendominasi kelimpahan dengan angka 84,55%. Biomassa glass eel tertinggi terjadi pada bulan maret sebesar 2157,32 kg. Demografi nelayan sidat di muara Sungai Cibuni berasal dari Desa Sinarlaut dan Desa Tegalbuleud, dengan dominasi sebaran usia 39-45 tahun, dominasi pendidikan pada Sekolah Lanjut Tingkat Pertama, dan dominasi telah bekerja selama 10-13 tahun. Pengelolaan glass eel di muara Sungai Cibuni memiliki atribut penghubung pengelolaan, adalah kebijakan pemerintah daerah yang dapat meningkatkan pengelolaan sidat di muara Sungai Cibuni., Indonesia has abundant eel, both in seed size and consumption size, but it has not been used properly. This research was conducted from February to June 2021. The purpose of the study was to identify and analyze the management factors of eel fisheries in the Cibuni River estuary, Sukabumi Regency. The benefit of this research is to provide information related to the socio-ecological factors of glass eel fisheries that can be used as a reference in resource management and eel fisheries in the Cibuni estuary, Sukabumi Regency. Glass eel sampling was carried out for five days in the dark moon phase each month. The estuary of the Cibuni River has good water quality with a range according to quality standards; the typology of the estuary also supports eels. The Cibuni River estuary has three types of eels, namely Anguilla bicolor bicolor, Anguilla marmorata and Anguilla nebulosa nebulosa. Anguilla bicolor bicolor dominates the abundance with a figure of 84.55%. The highest glass eel biomass occurred in March, which was 2157.32 kg. The demographics of eel fishermen in the Cibuni River estuary are from Sinarlaut Village and Tegalbuleud Village, with a dominance of 39-45 years of age distribution, dominance of education in Junior High School, and dominance of having worked for 10-13 years. The management of glass eels at the Cibuni River estuary has a management link attribute, namely local government policies that can improve eel management at the Cibuni River estuary.
Keyword: SES, Sidat, Sungai Cibuni

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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