Judul: Kesuburan Tanah pada Berbagai Tingkat Kerapatan Tajuk di Gunung Cibodas Ciampea, Bogor
Abstrak: Perubahan vegetasi di kawasan karst menyebabkan berkurangnya sumber hara dalam kesuburan tanah. Penelitian ini bertujuan menganalisis pengaruh kerapatan tajuk terhadap tingkat kesuburan tanah di ekosistem karst Gunung Cibodas Ciampea berdasarkan sifat fisika dan sifat kimia tanah. Kerapatan tajuk diukur menggunakan spherical densiometer (SD) kemudian contoh tanah terusik diambil di lima titik dengan kedalaman 0 - 60 cm. Contoh tanah kemudian dianalisis tekstur, pH, kandungan C-organik, kapasitas tukar kation (KTK), kejenuhan basa (KB), kandungan unsur P2O5 dan K2O, serta status kesuburan tanah ditentukan berdasarkan kriteria penilaian sifat tanah menurut Pusat Penelitian Tanah tahun 1995. Berdasarkan hasil analisis, status kesuburan tanah di Gunung Cibodas Ciampea tergolong dalam kategori sedang pada seluruh tingkat kerapatan tajuk. Hubungan antara tingkat kerapatan tajuk dan kesuburan tanah memiliki korelasi positif signifikan pada KTK dan korelasi negatif signifikan pada pH tanah.
Keyword: karst, kerapatan tajuk, kesuburan tanah, kimia tanah, spherical densiometer

Judul: Kesuburan Tanah pada Hutan Wakaf Kampung Muara, Kecamatan Pamijahan, Kabupaten Bogor, Jawa Barat
Abstrak: Pengetahuan tentang karakteristik dan kualitas tanah perlu diketahui untuk menilai dan memantau kesuburan tanah. Penelitian ini bertujuan untuk menentukan status kesuburan tanah Hutan Wakaf Kampung Muara Bogor. Penelitian dilakukan dengan mengambil sampel tanah terusik di lapangan pada tiga tingkat kerapatan tajuk dan dilanjutkan dengan analisis di laboratorium. Setelah dilakukan analisis, selanjutnya dilakukan penilaian sifat kimia tanah dan penilaian status kesuburan tanah. Hasil analisis laboratorium pada kerapatan tajuk rendah, sedang dan tinggi menunjukan pH tanah masam (pH 5,23; pH 4,58; dan pH 4,44), C-Organik tergolong tinggi (3,56%; 5,21% dan 7,98%), kandungan P potensial tinggi (63,45 mg/100g, 20,70 mg/100g, dan 54,47 mg/100g) kandungan K potensial rendah (26,61 mg/100g, 7,11 mg/100g dan 13,37 mg/100g), KTK tergolong tinggi (36,67 cmol/kg, 26,34 cmol/kg dan 28,22 cmol/kg) dan kejenuhan basa sangat rendah (24,57%, 6,30% dan 4,57%). Berdasarkan hasil analisis, status kesuburan tanah pada lokasi penelitian tergolong rendah., The knowledge of quality and characteristics of soil is a vital information for soil assessment and monitoring. This research is aiming to determine the soil fertility in Bogor Waqf Forest Kampung Muara. The research was conducted by collecting disturbed soil samples in three levels of canopy, and followed with laboratory analysis. After the samples are analyzed, an assessment of soil’s chemical properties and an assessment of soil fertility status were enacted. Results of Laboratory analysis on low, medium and high canopy density showed acidic soil pH values (pH 5,23; pH 4,58; and pH 4,44), C-Organic classified as high (3,56%, 5,21% and 7,98%), potential P content classified as high (63,45 mg/100g, 20,70 mg/100g and 54,47 mg/100g), potential K content classified as low (26,61 mg/100g, 7,11 mg/100g and 13,37 mg/100, CEC was high (36,67 cmol/kg, 26,34 cmol/kg and 28,22 cmol/kg), and base saturation was very low (24,57%, 6,30% and 4,57%). Based on the results of the analysis, soil fertility status of Bogor Waqf Forest was relatively low.
Keyword: hutan wakaf, kerapatan tajuk, kesuburan tanah, sifat tanah, status kesuburan tanah

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