Judul: Pengaruh Penyimpanan Biji Kopi pada Berbagai Tingkat Kelembaban Relatif terhadap Perubahan Kadar Air, Citarasa dan Perkembangan Mikroflora
Abstrak: Petani kopi di Indonesia umunya melakukan pengolahan kopi dengan cara kering. Kadar air awal biji kopi hasil pengolahan yang dilakukan mereka relatif masih tinggi (sekitar 15% hingga 20%) sehingga penyimpanan dalam jangka waktu lama sulit diharapkan.
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Judul: Pengaruh Kadar Air Awal, Jenis Wadah dan Kondisi Ruang Terhadap Viabilitas Benih Kopi (Coffea canephora) Apabila Periode Konservasi Delapan Minggu
Abstrak: Beracuan pada Paket Kebijaksanaan 24 Desember 1987 tentang deregulasi dan debirokratisasi komoditi ekspor di Indonesia, maka peningkatan produksi dan kualitas komoditi kopi harus segera ditangani dengan lebih intensif, sehingga nilai devisa yang dihasilkannya menjadi lebih tinggi lagi. Untuk menghasilkan komoditi kopi yang bermutu tinggi maka tanaman sumber yang digunakan harus merupakan tanaman yang baik dan resisten terhadap serangan hama maupun bibit penyakit (Wachyar, 1984). Syarat utama yang diperlukan untuk mendapatkan tanaman kopi yang baik adalah penggunaan benih kopi yang baik dan benar pula. Penelitian ini bertujuan untuk mengetahui pengaruh kadar air awal, jenis wadah, kondisi ruang, dan interaksinya terhadap viabilitas benih kopi apabila periode konservasi delapan minggu. Status viabilitas benih yang diamati dalam penelitian ini meliputi viabilitas potensial yang diukur dengan tolok ukur daya berkecambah, serta vigor kekuatan tumbuh dengan tolok ukur kecepatan tumbuh dan keserempakan tumbuh. Selain itu juga dilakukan pengukuran terhadap kadar air benih setelah masa konservasi. Agar benih kopi memiliki kadar air yang tetap tinggi kalau periode konservasi 2, 4 dan 6 minggu, maka benih sebaiknya berada dalam wadah plastik dengan kadar air awal 50-55% serta dalam kondisi ruang RH 90.4% dan suhu 27.4°C. Benih dalam wadah porus dengan kadar air awal yang lebih rendah serta berada dalam ruang RH 42.8% dan suhu 22.7°C akan mengalami penurunan kadar air yang sangat drastis. Wadah plastik bersifat resisten terhadap kelembaban, sehing- ga benih sulit mengadakan kesetimbangan kadar air dengan lingkungan di luar wadah. Hal seperti ini berlaku pula kalau periode konservasi 8 minggu, benih kopi dengan kadar air awal 50-55% dan berada dalam wadah plastik ternyata memiliki kadar air setelah masa konservasi yang masih tetap tinggi...
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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