Judul: Kualitas air pada pemeliharaan ikan nila Oreochromis sp intensif di kolam Departemen Budidaya Perairan Institut Pertanian Bogor
Abstrak: Tilapia Oreochromis sp. is one of the most importants freshwater fish that have a high potential of economic value to be an intensive culture. Water quality management is the major component that must be considered in increasing production. The application of a paddle wheel on aquaculture is used in order to be able to maintain the supply of oxygen, which required for the growth of fish. This study aimed to analyze the effect of water quality parameters on decreased in appetite and body resistance in an intensive culture of tilapia. The study was conducted by taking samples of water at depth ranged from 10 to 30 cm with different distances in pond culture. The samples were taken at 06.00 am and at 02.00 pm. Water quality parameters observed in this study were dissolved of oxygen (DO), temperature, pH, ammonia, and organic matter content. The results of study showed that dissolved of oxygen ranged from 5.5 to 7.6 mg/l; water temperatur ranged from 26.9 to 28.3 °C; pH ranged from 6.85 to 7.68; ammonia ranged from 0.0012 to 0.017 mg/l; and the organic matter content ranged from 11.16 to 38.44 mg/l KMnO4. The values of water quality parameters measured in the range of optimal. Decreased appetite in fish caused by the concentration level of ammonia (NH3) that have almost reached its upper limit and the high concentration of the total organic matter in the water, so that fish are more susceptible to disease. The operation of the paddle wheel was supplied enough of oxygen for aquatic organisms, so that the concentration of dissolved oxygen did not reduced.
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Judul: Kualitas Air dan Produksi Budidaya Ikan Nila (Oreochromis niloticus) dengan Feeding Rate Berbeda pada Sistem IMTA (Integrated Multi Trophic Aquaculture)
Abstrak: This research aims to knowing the quality of water by determinating optimal feeding rate on growth, survival, feeding efficiency, economic analysis and productivity of the Tilapia maintained by IMTA system. Tilapia fish which used in this study were about 6.68±0.63 cm length and 4.9±1.38 g weight on the average and 50 m2 stocking density. The container that used was 9 concrete pools with measurement of large 7 m2 for each pool. Intensive Tilapia farming with IMTA system had the best result in treatment by feeding 2.5% of biomass which could provide quality of water conditions in the appropriate range of water quality for cultivation such as temperature (25.2 to 31.1 ° C), pH (6.6 to 8.5) , DO (1.9 to 6.59 mg/l), ammonia (0.0003 to 0.0208 mg/l), nitrite (0.0048 to 0.179 mg/l), nitrate (0 to 0.403 mg/l) , phosphate (0.12 to 0.384 mg/l), survival rate (94.86±2.00%), the absolute length of (6.77±0.20 cm), absolute weight (35.28±1.93 g), SGR (2.96±0.07%), EP (229.65±28.39%), productivity could reach up to 14 665 g and profit up to Rp 553 360 was the best result of economic analysis and good quality of water with IMTA system could press feeding rate to 2.5%.
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Judul: Invers dari Matriks Tridiagonal Jacobi
Abstrak: Suatu matriks berukuran n×n dinamakan matriks tridiagonal jika untuk . Karya ilmiah ini memberikan algoritma yang mudah untuk menemukan invers ( dari matriks tridiagonal Jacobi yang simetrik dan nonsimetrik. Setiap elemen pada matriks tridiagonal ini adalah bilangan real. Terdapat 3 lema dan 2 teorema untuk menentukan . Lema pertama menunjukkan persamaan utama dalam membuktikan lema-lema dan teorema-teorema selanjutnya. Invers dari matriks yang simetrik dibuktikan oleh lema kedua yang menunjukkan elemen-elemen baris ke- dari . Selanjutnya, lema kedua dilengkapi dengan teorema pertama yang menunjukkan elemen-elemen dengan . Invers dari matriks yang nonsimetrik dibuktikan oleh lema ketiga yang menunjukkan elemen-elemen dengan dan elemen-elemen dengan dibuktikankan oleh teorema kedua.
Keyword: symmetric, nonsymmetric, matrix