Judul: Studi Kasus pada AMS Farm, Sukabumi
Abstrak: Kecenderungan pertanian organik saat ini tengah melanda dunia, terutama di negara-negara maju. Maraknya perkembangan pertanian organik di dunia dipacu oleh dampak revolusi hijau. Dampak negatif dari revolusi hijau diantaranya adalah adanya residu bahan kimia dalam makanan yang dikonsumsi, berkurangnya kesuburan tanah dan turunnya produktivitas lahan akibat penggunaan masukan kimia dalam pertanian dalam jangka panjang. Hal ini menyebabkan masyarakat makin sadar akan akibat yang ditimbulkannya. Secara perlahan perhatian masyarakat dunia mulai bergeser ke pertanian yang berwawasan lingkungan karena kini masyarakat sangat peduli terhadap alam dan kesehatan.
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Judul: Analisis keberlanjutan praktik pertanian organik di kalangan petani: kasus Desa Ketapang, Kecamatan Susukan, Kabupaten Semarang, Propinsi Jawa Tengah
Abstrak: Pertanian organik merupakan suatu sistem usahatani yang memanfaatkan sumber daya alam organik secara alami, bijaksana dan holistik, sebagai “input dalam” pertanian tanpa “input luar” tinggi kimiawi untuk memenuhi kebutuhan manusia khususnya pangan. Pertanian organik dikembangkan sesuai budaya lokal setempat, sehingga mampu menjamin keseimbangan aspek lingkungan, ekonomi, sosial budaya, serta mendorong terwujudnya fair trade bagi petani secara berkelanjutan. Gerakan organik melalui pertanian organik telah lama diinisiasi oleh berbagai pihak di level internasional, sebagai salah satu wujud perlawanan dari pembangunan pertanian yang berorientasi pada pertumbuhan dan sering disebut sebagai “Revolusi Hijau”. Gerakan organik kemudian berkembang menjadi sebuah filosofi yang diimplementasikan dalam sistem pertanian secara holistik, sehingga muncullah istilah pertanian organik sebagai sebuah alternatif sistem pertanian yang berkelanjutan.
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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