Judul: Deteksi Kemurnian Air Zamzam melalui Uji Konduktivitas Listrik.
Abstrak: Air zamzam merupakan air yang dianggap suci oleh umat Islam. Air zamzam dapat diperoleh dari keran air zamzam yang terletak di Masjidilharam, Kota Mekah, Arab Saudi. Tingginya permintaan serta larangan ekspor air zamzam untuk kepentingan komersial oleh pemerintah Arab Saudi menyebabkan banyaknya peredaran air zamzam yang tidak murni. Tujuan dari penelitian ini adalah menguji nilai konduktivitas listrik air zamzam, air baku lain, dan air campuran antara keduanya untuk mengetahui tingkat kemurnian air zamzam. Setelah diuji menggunakan alat konduktimeter, nilai konduktivitas listrik air zamzam berada pada rentang 800 μS/cm. Air baku lain nilai konduktivitas listriknya dibawah 150 μS/cm sedangkan air campuran nilainya tergantung oleh konsentrasi masingmasing air.
Keyword: air zamzam, air baku, kemurnian, konduktivitas listrik, konduktimeter

Judul: Perhitungan Nilai Konduktivitas Hidrolik Akuifer Melalui Uji Pemompaan Dengan Metode Thiem Di Leuwikopo, Dramaga, Bogor
Abstrak: Air merupakan salah satu sumberdaya alam yang sangat dibutuhkan oleh seluruh makhluk hidup, terutama manusia. Tujuan dari penelitian ini adalah untuk menentukan jenis tanah berdasarkan nilai konduktivitas hidrolik yang didapat melalui uji pemompaan pada sumur bor. Metode penelitian yang digunakan dalam penelitian ini secara umum terbagi menjadi tiga, yaitu studi literatur, studi lapangan, dan pengolahan data. Konduktivitas hidrolik dapat dihitung menggunakan metode Thiem untuk akuifer bebas. Uji pemompaan merupakan suatu metode yang dipergunakan secara luas untuk mengetahui karakteristik teknis akuifer. Pada penelitian ini, uji pemompaan dilakukan selama dua hari, dengan waktu pemompaan 8 jam per hari. uji pemompaan dibagi menjadi tiga tahap, yaitu uji pemompaan bertingkat, uji pemompaan kambuh, dan uji pemompaan menerus. Berdasarkan hasil penelitian, jenis akuifer di Leuwikopo, Dramaga, Bogor adalah akuifer bebas. Nilai konduktivitas hidrolik akuifer adalah 0,09 m/hari. Jenis tanah atau batuan di Leuwikopo, Dramaga, Bogor adalah liat, pasir, dan campuran kerikil.
Keyword: aquifer, hydraulic conductivity, Thiem method, pumping test

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