Judul: Kondisi Ekosistem Mangrove Berdasarkan Indikator Kualitas Lingkungan dan Ukuran Morfometrik Daun di Sebelah Utara dan Selatan Sungai Kembang Kuning, Cilacap, Jawa Tengah
Abstrak: Hutan mangrove merupakan suatu tipe hutan yang khas yang terdapat di sepanjang pantai atau muara sungai yang dipengaruhi oleh pasang surut air taut (Nontji, 1987). Segala macam tumbuhan yang terdapat dalam hutan mangrove saling berinteraksi dengan lingkungannya, baik yang bersifat biotik maupun abiotik. Seluruh sistem ini saling bergantung dan membentuk suatu ekosistem yang khas. Hutan mangrove di Segara Anakan, Cilacap merupakan sumberdaya alam yang langka dan ter1uas di Pulau Jawa yang masih tersisa. Makin meningkatnya aktivitas manusia di sekitar kawasan hutan mangrove, juga menimbulkan tekanan secara ekologis terutama dalam pemanfaatan areal hutan mangrove dan pencemaran lingkungan. Kondisi hutan mangrove di sepanjang Sungai Kembang Kuning mengalami kerusakan, baik yang di sebabkan oleh aktivitas manusia maupun secara alami.
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Judul: Kondisi ekosistem mangrove berdasarkan indikator kualitas lingkungan dan pengukuran morfometrik daun di muara sungai Bengawan Solo, Ujung Pangkah, Gresik, Jawa Timur
Abstrak: Pertumbuhan penduduk yang tinggi dan pesatnya pembangunan di wilayah pesisir menyebabkan tekanan ekologis terhadap ekosistem pesisir, khususnya ekosistem mangrove. Hal ini berdampak terhadap kerusakan ekosistem hutan mangrove baik secara langsung maupun tidak langsung. Demikian juga yang terjadi pada hutan mangrove di Jawa Timur, yang telah mengalami kerusakan baik akibat aktivitas manusia maupun secara alami. Penelitian ini bertujuan untuk menganalisis kualitas lingkungan mangrove di Muara Sungai Bengawan Solo, Ujung Pangkah, Gresik, Jawa Timur berdasarkan indikator kualitas lingkungan mangrove dan mengetahui kondisi ekosistem mangrove berdasarkan sebaran morfometrik daun mangrove.
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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