Judul: Analisis penawaran dan permintaan pulp dan kertas Indonesia di pasar domestik dan internasional
Abstrak: Industri pulp dan kertas sangat penting peranannya dalam perekonomian nasional, karena hampir semua aktivitas kehidupan manusia memanfaatkannya.
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Judul: Potensi permintaan dan penawaran pulp dan kertas di Indonesia
Abstrak: Kertas merupakan produk yang sangat penting sesudah kebutuhan fisik dan mental terpenuhi pada saat ini. Sejalan dengan laju perkembangan penduduk dan teknologi maka permintaan kertas di Indonesia terus meningkat yang otomatis meningkatkan pula permintaan pulp sebagai bahan baku utama kertas. Rata-rata tingkat pertumbuhan per tahun permintaan pulp dan kertas di Indonesia dari tahun 1987 1996 masing-masing adalah 14,3% dan 17,5% (Departemen Perindustrian dan Perdagangan, 1997). Dalam rangka memenuhi permintaan pulp dan kertas, maka produksi komoditi tersebut mutlak dilakukan. Tingkat pertumbuhan produksi pulp dari tahun 1987 - 1996 rata-rata per tahun mencapai 24,5%, sedangkan kertas 21,3% (Departemen Perindustrian dan Perdagangan, 1997). Tujuan dari penelitian ini adalah untuk mengetahui faktor-faktor yang mempengaruhi permintaan dan penawaran pulp dan kertas serta meramalkan permintaan dan penawarannya untuk tahun 1998 - 2003. Data yang digunakan dalam penelitian ini merupakan data sekunder yang mencakup periode tahun 1987 - 1996. Batasan penelitiannya adalah bahwa permintaan merupakan jumlah konsumsi per tahun baik untuk pulp maupun kertas. Sedangkan penawaran yang dimaksud adalah jumlah produksi setiap tahunnya untuk masing-masing komoditi tersebut. Analisis regresi linear digunakan untuk mencari hubungan antara peubah- peubah yang mempengaruhi permintaan dan penawaran pulp dan kertas di Indonesia, sedangkan demi efisiensi dalam rangka peramalan dipilih model regresi terbaik dari sejumlah subset model yang ada....
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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