Judul: Karakteristik Komunitas Fauna di Derah Intertidal Pantai Kamal Kecamatan Penjaringan, Jakarta Utara
Abstrak: Penelitian ini dilaksanakan di Desa Kamal Muara Kecamatan Penjaringan, Jakarta Utara, yaitu di daerah intertidal Pantai Kamal. Penelitian ini dimulai tanggal 8 ApriI 1988 dan selesai tanggal 8 Mei 1988 (selama satu bulan) Pada daerah intertidal terdapat berbagai macam biota, baik flora maupun fauna. Diantara fauna tersebut adalah komunitas benthos yang mendiami sedimen atau substrat. Dengan beragamnya kondisi lingkungan pada daerah ini, maka masing-masing spesies mempunyai cara adaptasi khusus untuk dapat memanfaatkan berbagai sumber yang ada pada habitat tersebut. Tujuan penelitian ini adalah untuk mendapatkan informasi mengenai karakteristik komunitas fauna benthos dengan mengkaji struktur komunitas, pola distribusi, similaritas, dan assosiasi jenis. Disamping itu juga dilihat beberapa faktor lingkungan yang mempengaruhi kehidupan benthos sebagai data penunjang .
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Judul: Struktur Komunitas di Perairan Pantai Batu Namprak, Sukabumi, Jawa Barat
Abstrak: Penelitian ini bertujuan untuk mempelajari struktur komunits rumput laut pada daerah intertidal Batu Namprak Sukabumi, Jawa Barat yang meliputi komposisi jenis, penutupan dan kepadatan serta kaitannya dengan faktor-faktor lingkungan yang mempengaruhinya. Penelitian dilakukan selama 2 bulan. Pengamatan dilakukan pada pagi dan siang hari saat surut melalui observasi visual "in situ" dan pengambilan contoh menurut garis transek dan plot kuadrat (50x50 cm). garis transek ditentukan tegak lurus pantai ke arah tubir. Pada setiap lima meter sepanjang garis transek tersebut diambil sampel rumput laut pada are plot (50x50 cm), selanjutnya dicatat pula penutupan rumput laut, subtrat dasar serta kedalaman air. Pemeriksaan sampel dilakukan dengan cara sortasi berdasarkan marga dan penimbangan berat (bobot) basah
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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