Judul: Pengaruh Curah Hujan terhadap Infiltrasi pada Tanah Terbuka
Abstrak: Keterbatasan dan ketidak teraturan curah hujan sering menjadi sebab penurunan dan kegagalan usaha pertanian . Berbagai usaha perbaikan ditempuh guna meningkatkan intensifikasi lahan. Pengaturan jadwal tanam merupakan salah satu cara dalam usaha ini . selain itu usaha perbaikan fisik tanah juga dilakukan . Penambahan bahan organik (BO) diketahui berpengaruh positif terhadap daya simpan air tanah, sealin juga menambah kesuburan tanah. Penelitian ini bertujuan mempelajari pengaruh curah hujan terhadap pinfiltrasi pada tanah terbuka yang diberibahan organik (kotoran hewan).
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Judul: Hubungan Kadar Air Tanah dengan Curah Hujan dan Sifat Fisik Tanah pada Penggunaan Lahan Berbeda di Kecamatan Warunggunung, Kabupaten Lebak.
Abstrak: Ketersediaan air pada suatu lahan sangat berhubungan dengan karakteristik tanahnya. Karakteristik tanah suatu lahan banyak dipengaruhi oleh jenis tutupan lahan, karena perbedaan jenis vegetasinya. Pengaruh tersebut akibat perbedaan kadar bahan organik yang dihasilkan maupun kedalaman perakaran tanamannya. Kondisi tersebut berpengaruh terhadap kemampuan tanah dalam menyimpan air. Kemampuan tanah dalam menyimpan air hujan, sangat diperlukan oleh petani dalam merencanakan irigasi. Penelitian ini bertujuan untuk melihat pengaruh curah hujan terhadap kadar air tanah. Penelitian dilakukan pada lahan kebun campuran dan lahan terbuka. Pengamatan curah hujan dan kadar air tanah di kebun campuran dan lahan terbuka dilakukan selama 28 hari. Hasil penelitian menunjukkan bahwa pada curah hujan tinggi, kadar air tanah di kedua lahan berada di atas kondisi kapasitas lapang. Kadar air di lahan terbuka lebih tinggi dibanding kebun campuran. Pada curah hujan rendah, kadar air di kebun campuran cenderung lebih tinggi dibanding lahan terbuka. Penurunan kadar air tanah di lahan terbuka relatif lebih cepat dibanding di lahan kebun campuran, sehingga berpeluang lebih cepat membutuhkan irigasi jika tidak segera turun hujan.
Keyword: curah hujan, irigasi, kadar air tanah

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