Judul: Keberadaan H2S Pascaaerasi Hipolimnion pada Kawasan Keramba Jaring Apung (KJA) di Danau Lido, Bogor, Jawa Barat
Abstrak: Tujuan dari penelitian ini adalah mempelajari keberadaan hidrogen sulfida (H2S) pascaaerasi hipolimnion dengan lokasi penelitian di Danau Lido, Bogor, Jawa Barat. Penelitian dilakukan dari bulan Mei hingga Agustus 2011 dengan pengambilan sampel pada 5 titik yang ditentukan secara purposive sampling berdasarkan arus yang keluar dari outlet alat aerasi, yaitu 0; 1,5; 3; 4,5; dan 8 m. H2S merupakan salah satu bentuk sulfur anorganik yang bersifat racun (toksik) yang dihasikan dari aktivitas biologis bakteri pada kondisi anaerob bahan-bahan organik yang mengandung sulfur serta berasal dari hasil reduksi sulfat (SO42-) di dalam lapisan sedimen. H2S banyak ditemukan di lapisan hipolimnion, karena dalam kondisi oksigen yang sangat rendah akan terjadi akumulasi H2S akibat adanya peningkatan pertumbuhan bakteri anaerob. Aerasi hipolimnion yang dilakukan diharapkan dapat meningkatkan konsentrasi oksigen sehingga proses perombakan bahan organik yang mengandung sulfur tidak menghasilkan H2S yang merugikan bagi kehidupan biota akuatik di dalam danau. Hasil penelitian ini menunjukkan bahwa aerasi yang dilakukan selama 10 jam mampu menurunkan konsentrasi H2S di lapisan hipolimnion Danau Lido, rata-rata sebesar 51,85%. Penurunan terbesar terjadi pada jarak 3 m dari titik outlet aerasi (60%). Setelah aerasi dihentikan konsentrasi hidrogen sulfida mengalami peningkatan, akan tetapi dengan konsentrasi lebih kecil dibandingkan sebelum aerasi dilakukan.
Keyword: aerasi hipolimnion, hidrogen sulfida

Judul: Keberdaan Fosfat Pascaaerasi Hipolimnion pada Lokasi Keramba Jaring Apung di Danau Lido, Bogor, Jawa Barat
Abstrak: The purpose of this research is to study about phosphate presence after hypolimnetic aeration in Lido Lake, Bogor, West Java. The research is carried out from May to July 2011 with 5 sampling spot which is decided by purposive sampling based on the aeration equipment outflows, consist of 0 m;1,5 m; 3 m; 4,5 m; and 8 m. Orthophosphate is one of dissolved inorganic phosphate form that can be used by algae and aquatic plant directly. The presence of orthophosphate is affected by dissolved oxygen concentration in water. Orthophospate mostly found in hypolimnetic layer, this is happened because orthophosphate can form a bond and precipitation with Fe, Ca, or Al ion in the oxic condition, then fall to the bottom of water. In the other side, in anoxic condition, the bond between orthophospate and Fe, Ca, or Al ion will be released. This research aim to observe the presence of phosphate after hypolimnetic aeration. This aeration is expected to increase the ability of ions to make a bond and do precipitation with orthophosphate. The research showed that aeration which is done for 10 hours can decrease the orthophosphate concentration in hypolimnetic layer of Lido Lake for 21,05- 97,56%. The most slope is occurred in 3 m distance from the outlet of aeration (97.56%). After the aeration, the decrease of orthophosphate concentration still can be maintained for 5 hours. The concentration of orthophosphate begin to increase after 10 hours from the end of aeration.
Keyword: 

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
Keyword: