Judul: Penelaahan Tanah-Tanah Bersifat Oksik dari Daerah Cipayung, Bogor
Abstrak: Tujuan penelitian ini adalah untuk menelaah dan menghapus keraguan tentang terdapatnya sifat-sifat oksik pada tanah-tanah di Daerah C ipayung, Bogor dari penelitian yang telah dilakukan sebelumnya (Iswahyudi, 1985) dan mengklasifikasikannya menurut Taksonomi Tanah. Contoh tanah dari tiga profil (PI, P2, dan P3) yang telah diambil kemudian dianalisis sifat-sifat kimia, tekstur, dan mineral pada fraksi I V (200 - 100 mikron) maupun mineral liatnya (lebih kecil dari 2 mibon).
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Judul: Penilaian tingkat pelapukan, karakteristik dan klasifikasi tanah-tanah bersifat andik dari desa sukamantri, kabupaten bogor
Abstrak: Penilitian ini bertujuan mempelajari tingkat pela- pukan dikaitkan dengan bahan induk dan umur pada jenis tanah Andosol dan Latosol, serta karakter dan klasifikasinya menurut sistem Taksonomi Tanah berkaitan dengan sifat andik sebagai penciri. Tanah-tanah tersebut terletak pada satu transek lereng di kebun percobaan IPB, Sukamantri. Sifat andik mencerminkan tanah-tanah abu dan tufa volkanik yang banyak mengandung abu volkanik vitrik, cinder dan bahan piroklastik vitrik lainnya. Biasanya, bobot isi tanah rendah dan komplek pertukaran didomina- si oleh bahan amorf. Sifat andik tercermin pada kategori suborder dan subgroup. Penonjolan sifat tersebut dipengaruhi oleh sifat dari bahan induk dan waktu erupsi yang tidak sama. Latosol terbentuk dari tufa volkanik yang lebih tua, sedangkan Andosol berkembang dari abu volkanik yang lebih muda.
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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