Judul: Fluks metana (CH4) oleh tanah hutan di bawah tegakan sengon (Paraserianthes falcataria (L) Nielsen) di hutan Gunung Bunder BKPH Leuwiliang KPH Bogor Perum Perhutani Unit III Jawa Barat
Abstrak: Keseimbangan panas bumi yang dapat mengganggu kehidupan manusia dan ekosistem tegantung pada kadar gas-gas rumah kaca di atmosfir (GRK). Peningkatan kadar gas-gas rumah kaca di atmosfir mengakibatkan efek rumah kaca (ERK). Metana sebagai penyusun gas rumah kaca terpenting setelah karbon dioksida, dalam kontribusinya terhadap pemanasan global, perlu diperhatikan keberadaannya. Salah satu cara hilangnya (perosot) metana dari atmosfir berlangsung melalui oksidasi oleh bakteri methanotrop di dalam tanah. Oksidasi ini berlangsung dengan baik pada tanah-tanah yang aerob (tidak tergenang). Ditinjau dari kondisi tanah di bawah tegakan sengon di Hutan Gunung Bunder yang aerob, maka diduga tanah tersebut merupakan media yang baik bagi kelangsungan methanotrop dalam mengoksidasi metana. Penelitian ini bertujuan untuk mengetahui konsentrasi ambien metana (gas buangan metana), fluktuasi harian konsentrasi ambien metana, korelasi antara kelembaban udara dan suhu udara dengan konsentrasi ambien metana, fluks metana, fluktuasi harian fluks metana dan faktor-faktor yang mempengaruhi fluks metana di bawah tegakan sengon di Hutan Gunung Bunder.
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Judul: Fluks metana (CH4) oleh tanah hutan di bawah tegakan rasamala (Altingia excelsa) di gunung Bunder BKPH Leuwiliang KPH Bogor Perum Perhutani Unit III Jawa Barat
Abstrak: Salah satu isu lingkungan yang dewasa ini dianggap penting oleh manusia adalah terjadinya pemanasan global global warming). Hal ini timbul karena terjadinya peningkatan gas-gas rumah kaca (GRK) di atmosfer. Gas- gas rumah kaca ini yang mengakibatkan efek rumah kaca (ERK). Gas metana merupakan gas rumah kaca kedua terpenting setelah CO2 (Salvato, 1992). Tanah di hutan tropis diketahui sebagai faktor yang penting dalam menentukan kadar metana di atmosfer. Hutan tropis yang mempunyai tanah kering berfungsi sebagai rosot metana karena memberikan kondisi yang baik bagi pertumbuhan dan perkembangan bakteri mechanotropic. Sebaliknya hutan yang tergenang merupakan sumber (sources) emisi metana cukup besar, karena kondisi ini cocok bagi bakteri methanogens yang menghasilkan metana. Penelitian ini bertujuan untuk mengetahui konsentrasi ambien metana, laju fluks metana, fluktuasi harian konsentrasi ambien metana dan faktor-faktor yang mempengaruhi laju fluks metana oleh tanah hutan di bawah tegakan Rasamala. ...
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Judul: The Construction of Greedy SVP LLL Algorithm
Abstrak: A lattice is a set of all integer linear combination of a set of linearly independent vectors in ℝ𝑛���. The independent vectors are called bases of lattice. Any lattice can be generated from many bases, and these bases have the same cardinality. In the lattice, the most fundamental and renowned problem is the Shortest Vector Problem (SVP). SVP is a tracking problem of the shortest nonzero vector in a lattice with equivalent bases. In two dimensions, SVP problem has resolved exactly by Gauss’ algorithm. When the lattice dimension is higher than two, A.K. Lenstra, H.W. Lenstra and L. Lovasz gave a LLL algorithm to compute approximation of nonzero shortest vector in the lattice. Reduced bases solution obtained from LLL algorithm still be an approximation and has polynomial running time of arbitrary dimension which large enough. In 1994, Schnoor and Euchner modified this LLL algorithm as a new variant which later was named deep insertion LLL algorithm. This algorithm is a modified version of the LLL algorithm to the terms of the exchange step to improve the accuracy of output of LLL reduced bases and applying it to the subset sum problem. The purpose of this research are: (1) Reconstruct the LLL algorithm and deep insertion LLL algorithm using a geometric approach. (2) Construct a greedy SVP LLL algorithm. (3) Implement the three algorithms in a symbolic programming language, and evaluate them experimentally. A bases ℬ=[𝐛���1,𝐛���2,…,𝐛���𝑛���] in ℝ𝑚��� is called reduced LLL with parameter 𝛿��� if satisfies: (a) |𝜇���𝑗���𝑖���|≤12, for every integer 𝑖���,𝑗��� with 1≤𝑖���<𝑗���<𝑛���. (b)𝛿���‖𝜋���𝑗���(𝐛���𝑗���)‖2≤‖𝜋���𝑗���(𝐛���𝑗���+1)‖2, for 𝑗���=1,2,…,𝑛���−1,where 𝛿��� is a reduced parameter of real numbers with 14<𝛿���<1. The first requirement is the reduced basis 𝛿��� must “nearly orthogonal” and in its computation case, this requirement can be reached out by using the Gram-Schmidt’s orthogonalization. While the second requirement is called exchange step, or used to called as Lovasz condition. By using both of these requirements, then they establish the LLL algorithm. Then, Schnoor and Euchner modify the LLL algorithm based on the requirements of the exchange step called the deep insertion LLL algorithm, where the exchange step is based on the comparison of the projected vector in orthogonal complement [𝐛���1,𝐛���2,…,𝐛���𝑘���−1]⊥ after j-th reduction. To construct greedy SVP LLL algorithm, the requirements of the exchange step is based on purely by comparing norm of lattice 𝐛���𝑗��� with norm lattice 𝐛���𝑖��� for 𝑖���=1,2,3…,𝑗���−1. The process of insertion reduced vector after the exchange step also has done greedily. Then, we calculate the number of arithmetic operation in greedy SVP LLL algorithm for further analysis. The result of our exprimentation for three algorithms on the certain matrix size shows that the running time of the three algorithms increases propotional to the size of the matrix. The result also shows that by using 𝛿���=34 for the LLL algorithm and the deep insertion LLL algorithm, and the greedy SVP LLL algorithm which is a new variant made by using no parameter of 𝛿���, outperform of the other of two previous algorithm in terms of speed with the same output.
Keyword: LLL algorithm, LLL deep insertion algorithm, greedy SVP LLL algorithm