Judul: dampak Kebakaran Hutan Terhadap Sifat Fisik dan Sifat Kimia Tanah (Studi Kasusdi Hutan Sekunder Haurbentes Jasinga-Bogor)
Abstrak: Kebakaran hutan merupakan salah satu perisliwa alam yang dapal menyebabkan kerusakan dan musnahnya hutan dalam waktu yang sangal cepat. Rusaknya hutan ini melipuli hilangnya keanekaragaman tumbuhan dan satwa serta musnahnya plasma nutfah. Kebakaran hutan yang menimbulkan kerusakan ekosistem dunia sampai sekarang ini belum dapat ditanggulangi secara maksimal. Dampak kebakaran hulan dapat merugikan kehidupan manusia. Sedangkan beberapa keuntungan dari kebakaran hutan adalah memperoleh tunas atau rumpul muda untuk lemak serta untuk mengurangi timbunan bahan bakar di lantai hulan sehingga lahan hulan siap ditanami. Adapun dampak negatif kebakaran hulan terhadap tanah adalah penurunan kualitas lahan hulan yang meliputi sifat fisik dan kimia tanah, erosi, kapasitas penyimpanan air tanah dan penghilangan serasah serta humus, yang seluruhnya sangat mempengaruhi pertumbuhan pohon.
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Judul: Dampak kebakaran hutan terhadap tumbuhan bawah dan sifat kimia tanah di hutan pendidikan Gunung Walat-Sukabumi
Abstrak: Hak cipta Kebakaran hutan dan lahan saat ini dipandang telah menjadi salah satu bentuk gangguan terhadap pengelolaan hutan dan lahan. Akibat negatif yang ditimbulkan cukup besar misalnya kerusakan ekologis, menurunnya estetika, merosotnya nilai ekonomi hutan dan produktivitas tanah, perubahan iklim mikro maupun global, menurunkan keanekaragaman sumberdaya alam hayati dan ekosistemnya. Penelitian ini bertujuan untuk menilai dampak terjadinya kebakaran hutan terhadap tumbuhan bawah dan perubahan kandungan sifat kimia tanah periode 3 tahun setelah terbakar. Diharapkan dapat diperoleh informasi tentang perkembangan pemulihan kondisi ekosistem hutan dilihat dari perkembangan tumbuhan bawah dan perubahan kondisi kandungan kimia tanah yang akan berpengaruh terhadap perubahan tingkat kesuburan tanah di areal tersebut setelah terjadi kebakaran hutan...
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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