Judul: Kemampuan Tanah Menahan Air dan Kepekaan Erosi Tanah Pada Berbagai Umur Pembukaan Lahan Alang-Alang di Daerah Transmigrasi Barubara Martapura, Sumatera Selatan
Abstrak: Penelitian ini bertujuan untuh melihat pengaruh umur pembukaan lahan terhadap kemampuan tanah menahan air, menetapkan nilai kepekaan erosi tanah dengan menggunakan nomograf (Wischmeier, Johnson dan Cross, 1971) dan melihat hubungannya dengan umur pembukaan lahan, dan menduga besarnya erosi yang dan terjadi dengan sistim usahatani gang ada di daerah Baturaja Bartapura, Sumatera Selatan.
Keyword: 

Judul: Laju infiltrasi tanah pada berbagai umur pembukaan dan sistim pengelolaan lahan alang-alang dari podsolik merah kuning daerah transmigrasi Baturaja - Martapura Sumatera Selatan
Abstrak: Untuk menghindari terjadinya kerusakan tanah akibat pembukaan lahan yang terus-menerus dan penggunaannya secara maksimal, maka perlu menggunakan kaedah-kaedah konservasi tanah dan air dalam mengelola lahan tersebut sebagai lahan pertanian. Pada dasarnya konservasi tanah dan air adalah memperbesar laju infiltrasi dan memperkecil aliran permukaan. Tinggi rendahnya laju infiltrasi sangat berpengaruh terhadap simpanan air bawah tanah dan laju penyediaan air untuk tanaman. Oleh karena itu kemampuan tanah untuk menginfiltrasikan air perlu ditingkatkan dan dipertahan- kan. Metode pembukaan lahan dan sistim pengelolaan lahan selanjutnya yang dilakukan petani, dapat mempengaruhi tinggi rendahnya laju infiltrasi lahan tersebut. Tujuan penelitian ini adalah untuk mengetahui pengaruh umur pembukaan lahan alang-alang terhadap laju infiltrasi tanah, dan untuk membantu usaha mencari keserasi an dan keseimbangan antara metode pembukaan lahan dan pengelolaan lahan selanjutnya, sehingga produktivitas tanah dapat ditingkatkan dan dipertahankan. Pengukuran infiltrasi dilakukan pada tujuh tingkat umur pembukaan lahan alang- alang di Daerah Transmigrasi Baturaja-Martapura Sumatera Selatan, pada jenis tanah Podsolik Merah Kuning, kemiring- an lereng, dan vegetasi yang relatif sama. Berdasarkan penelitian ini, laju infiltrasi awal dari lokasi-lokasi pengamatan bervariasi dari 33.4 cm/jam sampai 169.1 cm/jam. Hal ini terjadi karena adanya perbedaan kadar air tanah sebelum dilakukan pengukuran, dan perbedaan sifat-sifat fisik tanah dari lokasi-lokasi pengamatan tersebut…dst
Keyword: 

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