Judul: Analisis Kapasitas Simpan Air pada DAS Cisukabirus, Kabupaten Bogor, Jawa Barat
Abstrak: Kerusakan DAS dapat ditandai dengan terjadinya perubahan tata guna lahan dari daerah tangkapan hujan berubah menjadi tanah terbuka. Tujuan dari penelitian ini adalah menentukan status daya dukung lingkungan DAS Cisukabirus, menghitung kapasitas simpan air, serta memberikan rekomendasi dalam upaya pengelolaan limpasan di DAS Cisukabirus. Metode yang digunakan berupa analisis data dari peta tata guna lahan, serta data iklim dari tahun 2006 sampai 2015. Status daya dukung lingkungan DAS Cisukabirus tergolong kedalam overshoot dengan nilai kebutuhan sebesar 143.2 x 106 m3/tahun dan ketersediaan air sebesar 34.24 x 106 m3/tahun, sehingga terjadi defisit air sebesar 108.9 x 106 m3/tahun. Kapasitas simpan air pada DAS Cisukabirus pada tahun 2015 diperoleh sebesar 3.2 x 106 m3/tahun. CHlebih diperoleh sebesar 22.4 x 106 m3/tahun dan limpasan yang terjadi sebesar 8.9 x 106 m3/tahun, sehingga pengisian air tanah sebesar 13.6 x 106 m3/tahun. Dalam pengelolaan kelebihan limpasan pada DAS Cisukabirus dapat dilakukan konservasi dengan membangun lubang resapan biopori, sumur resapan, serta penghijauan.
Keyword: DAS Cisukabirus, daya dukung lingkungan, kapasitas simpan air, limpasan

Judul: Analisis Kapasitas Simpan Air pada DAS Cisarua, Kabupaten Bogor
Abstrak: Watershed degradation could be characterized by changes in land use of catchment area with low run off coefficient to bare land with high run-off coefficient. Water balance calculation using Tornthwaite equation could be used to calculate fluctuation of water storage in a region. Water balance analysis was conducted at the Cisarua watershed with total area of 2491.90 ha. The objective of this research were to analyse water storage capacity, to calculate water avaibility (based on rainfall data), to calculate water demand, and to provide recommendations of run-off and groundwater recharge management in Cisarua watershed areas. Based on ideal ratio of run-off and groundwater recharge, the composition of the forest area of 50% in Cisarua watersheds is considered ideal, because it has a percentage of run-off by 51%. Residential area composition in Cisarua watershed (30%) is considered ideal, because the run off percentage is 49%. Environmental carrying capacity based on water balance of an area could be determined by calculating the capacity of water availability in the region. With a density of 2080 habitant / km2 and precipitation of 1870.1 mm / year, it could know that Cisarua watershed areas in 2010 were in the state of overshoot. Conservation methods that could be used in efforts to manage run-off excess were the construction of infiltration wells and reforestation
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Judul: The Exploration of Discrete Logarithm over Finite Field GF(3m)
Abstrak: The security of many public~key algorithms is based on the problem of finding discrete logarithms. The generalized discrete logarithm problem is the following: given a finite cyclic group G of order n, a generator a of G, and an element fl E G, find the integer x, 0 ~ x ~ n - 1, such that 0: = fl. Algorithm for discrete logarithm problem focused on Menezes et al. (1997) that consist of exhaustive search algorithm, the baby-step giant-step algorithm, Pollard's rho algorithm, Pohlig-Hellman algorithm, and index-calculus algorithm. These algorithms are explorated to be used in discrete logarithm problem over finite field GF(3m ). The exploration also produces some algorithms, i.e. naif negative algorithm, baby-step mother-step algorithm, baby-step mother free-step algorithm, and baby-step free-step algorithm. All algorithms implemented using Maple 11. The Pohlig-Hellman and baby-step giant-step algorithms are efficient enough to be used in discrete logarithm problem over finite field GF(3m ) for m < 20.
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