Judul: Status Kualitas Air dan Tingkat Pencemaran Danau Hias Gold Coast, Pantai Indah Kapuk, Jakarta Utara.
Abstrak: Kualitas air di perairan Danau Hias Gold Coast dipengaruhi oleh limbah domestik di sekitar perairan. Penelitian ini bertujuan untuk menentukan status kualitas air dan tingkat pencemaran perairan Danau Hias Gold Coast, Pantai Indah Kapuk, Jakarta Utara. Pengambilan data kualitas air dilakukan setiap bulan dari Juli 2015 sampai Juni 2016 pada lima stasiun pengamatan. Terdapat beberapa parameter kualitas air yang selalu melebihi baku mutu, yaitu BOD5, COD, amonia, hidrogen sulfida, fosfat total, dan kekeruhan. Status kualitas air ditentukan menggunakan Indeks Pencemaran dan Indeks Canadian Council of Ministers of the Environment. Hasil penelitian menunjukkan tingkat pencemaran perairan menurut Indeks Pencemaran dikategorikan dalam perairan yang tercemar sedang. Berdasarkan pendekatan yang digunakan, status indeks kualitas air CCME lebih mewakili kondisi perairan daripada IP. Status pencemaran Danau Gold Coast menurut indeks kualitas air CCME tergolong sangat buruk. Tingkat pencemaran pada musim kemarau lebih tinggi dibandingkan dengan musim hujan.
Keyword: indeks CCME, indeks pencemaran, kualitas air, limbah domestik

Judul: Status kualitas air Danau Crown Golf, Pantai Indah Kapuk, Jakarta Utara
Abstrak: Danau Crown Golf merupakan perairan buatan yang terletak di antara perumahan warga sehingga banyak menerima bahan pencemar dari limbah domestik. Hal ini dikhawatirkan akan menurunkan kualitas perairan danau. Penelitian dilakukan dimaksudkan untuk menentukan status pencemaran perairan di Danau Crown Golf berdasarkan analisis Indeks Pencemaran (IP) dan Indeks STORET. Penelitian dilaksanakan pada Bulan November 2014–Februari 2015, dengan interval satu bulan. Kondisi perairan danau secara visual berwarna kehijauan dan berbau. Analisis contoh air dan sedimen menunjukkan bahwa terdapat beberapa parameter kualitas air yang tidak memenuhi standar baku mutu kelas III menurut PP No 82 Tahun 2001, di antaranya adalah BOD5, COD, nitrit, dan sulfida. Indeks Pencemaran menunjukkan bahwa kondisi perairan danau tercemar ringan hingga sedang dengan kisaran nilai 4,3 hingga 9,4. Hasil ini berbeda dari status yang didapat dengan menggunakan Indeks STORET, diketahui kondisi perairan danau tercemar sedang hingga berat dengan kisaran nilai -36 hingga -38. Kondisi perairan Danau Crown Golf termasuk kedalam kategori tercemar ringan sampai dengan berat.
Keyword: Pollution Index, STORET Index, water quality

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