Judul: Characteristics of Pyrolysis Charcoal from Kenaf (Hibiscus cannabinus L.) Stem with Pyrolysis Carbonization
Abstrak: Karbonisasi pirolisis dipilih dalam penelitian ini karena metode ini memiliki kelebihan, yaitu tidak diperlukannya bahan tambah pada saat proses karbonisasi. Karbonisasi pirolisis menghasilkan produk berupa arang pirolisis. Limbah batang kenaf yang cukup banyak dan belum dimanfaatkan dengan optimal, mendasari penggunaan batang kenaf pada penelitian ini. Penelitian ini bertujuan untuk mengetahui pengaruh karbonisasi terhadap karakteristik arang pirolisis batang kenaf, serta mengetahui suhu dan waktu yang terbaik dalam melakukan karbonisasi pirolisis. Pada penelitian ini karbonisasi dilakukan dengan variasi suhu 175 °C, 200 °C, dan 225 °C dengan waktu karbonisasi 3, 4, dan 5 jam. Karakteristik yang diuji meliputi komponen kimia bahan, analisis proksimat arang hasil karbonisasi, daya jerap polutan, dan daya jerap iodin. Hasil pada penelitian ini menunjukkan bahwa, daya jerap polutan dan daya jerap iodin dari arang batang kenaf menjerap dengan baik dibandingkan dengan daya jerap batang kenaf sebelum dijadikan arang. Berdasarkan hasil pengujian daya jerap polutan dan total bilangan iodin, didapatkan arang terbaik pada suhu 225 °C selama suhu 4 jam., Pyrolysis carbonization was chosen in this study because this method has an advantage that it does not require additional materials during the carbonization process. Pyrolysis carbonization produces a product in the form of pyrolysis charcoal. There is a lot of kenaf stems and it has not been used optimally, underlies the use of kenaf stems in this study. This study aims to determine the effect of carbonization on the characteristics of pyrolysis charcoal from kenaf stems, as well as to determine the best temperature and time to carry out pyrolysis carbonization. In this study, carbonization was carried out with variations in temperature of 175 °C, 200 °C, and 225 °C with carbonization times of 3, 4, and 5 hours. The characteristics tested include the chemical components of the material, proximate analysis of carbonized charcoal, pollutant adsorption capacity, and iodine adsorption capacity. The results of this study indicate that the adsorption capacity of the pollutant and the iodine adsorption capacity of the kenaf stem charcoal is better than the adsorption capacity of the kenaf stem before being made into charcoal. Result showed that pollutant adsorption test and the total number of iodine, the best charcoal was obtained at a temperature of 225 °C for 4 hours.
Keyword: Arang pirolisis, batang kenaf, daya jerap iodin, daya jerap polutan, pirolisis, Charcoal pyrolysis, iodine number, kenaf stem, pollutants adsorbtion, pyrolysis

Judul: Characteristics of Kenaf Fiber Charcoal (Hibiscus cannabinus L.) With Pyrolysis Carbonization
Abstrak: Serat kenaf merupakan serat yang cukup potensial untuk dijadikan sebagai bahan baku arang aktif melalui proses karbonisasi pirolisis. Proses ini lebih dipilih karena waktu proses yang digunakan relatif lebih singkat dan efisien dibandingkan dengan karbonisasi hidrotermal. Namun, ada beberapa hal yang harus dievalusi untuk menganalisis karakteristik arang pirolisis serat kenaf hasil karbonisasi pirolisis serta menganalisis pengaruh suhu dan waktu dalam proses karbonisasi pirolisis terhadap sifat arang serat kenaf dan daya jerap polutannya. Proses karbonisasi pirolisis dilakukan pada suhu 175 oC, 200 oC, 225 oC dengan waktu selama 3, 4, dan 5 jam. Karakteristik yang dianalisis dalam penelitian ini antara lain komponen kimia dan analisis proksimat dari serat kenaf, sedangkan dari arang yang dihasilkan, dianalisis rendemen, kadar air, kadar abu, kadar zat terbang, kadar karbon terikat, daya jerap iodin, dan daya jerap polutan (amonia, kloroform, formaldehida, dan benzena). Hasil penelitian menunjukkan interaksi antara suhu dan waktu karbonisasi pirolisis berpengaruh nyata terhadap kadar zat terbang, karbon terikat, daya jerap amonia dan daya jerap kloroform. Namun, interaksi antara suhu dan waktu karbonisasi pirolisis tidak memberikan pengaruh yang nyata pada daya jerap benzena, kadar air, dan kadar abu. Arang pirolisis terbaik didapatkan pada suhu 200oC selama 5 jam dengan daya jerap iodin sebesar 148,19 mg/g, Kenaf fiber is a fiber that has potential to be used as raw material for activated charcoal through the pyrolysis carbonization process. This process is preferred because the processing time used is relatively shorter and more efficient than hydrothermal carbonization. However, there are several things that must be evaluated to analyze the characteristics of the pyrolysis charcoal of kenaf fiber asa result of pyrolysis carbonization and to analyze the effect of temperature and time in the pyrolysis carbonization process on the characteristics of the kenaf fiber charcoal and its pollutant adsorption capacity. The pyrolysis carbonization process was carried out at temperatures of 175 oC, 200 oC, 225 oC for 3, 4, and 5 hours. The characteristics analyzed in this study included chemical components and proximate analysis of kenaf fiber, while the resulting charcoal was analyzed for yield, moisture content, ash content, volatile matter content, bound carbon content, iodine adsorption capacity, and pollutant adsorption capacity (ammonia, chloroform, formaldehyde, and benzene). The results showed that the interaction between temperature and time of pyrolysis carbonization had a significant effect on volatile matter, bound carbon, ammonia adsorption capacity and chloroform adsorption capacity. However, the interaction between temperature and time of pyrolysis carbonization did not have a significant effect on the adsorption capacity of benzene, moisture content, and ash content. The best pyrolysis charcoal was obtained at 200oC for 5 hours with an iodine adsorption capacity of 148.19 mg/g
Keyword: Arang pirolisis, daya jerap iodin, Daya jerap polutan, Karbonisasi pirolisis, Serat kenaf, Pyrolysis charcoal, Iodine adsorption capacity, Pollutant adsorption capacity, Pyrolysis carbonization, Kenaf fiber

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