Judul: Pemanfaatan log diameter kecil jenis sengon (Paraserianthes falcataria L. Nielsen), cempaka (Elmirillia ovalis (Miq.) Dandy), dan manglid (Manglietia glauca BI.) sebagai bahan baku papan partikel
Abstrak: INTRODUCTION : The degradation of natural forests has made plantations forest and community forests is growing up, supply of raw materials for wood processing industry slowly shifted from natural forests to plantations and community forests. The ability of wood that can grow in a relatively short time make the harvesting time usually done more quickly because of the growing needs of raw materials, so in general logs produced from plantations forest is a type of small diameter logs. The way to optimize the small-diameter logs is by producing composite products, one of them is particle board. The purpose of this research is to evaluate the quality of particle board from small diameter logs with a low density, which is sengon, cempaka, manglid and mixtures of them. MATERIAL AND METHOD : The raw materials used are wood particles of sengon, cempaka, and manglid using 12% UF adhesive and 2% paraffin content. There are four types of boards are made, that is particle board with a pure composition of each type and mixture composition of sengon: cempaka: manglid 1 : 1 : 1 with two different density target, that is 0.4 g/cm3 and 0.6 g/cm3. Compression performed with a temperature of 150 ° C and pressure of 25 kg/cm2 for 10 minutes, with particle board size is 30 cm x 30 cm x 1 cm. RESULT : The test results obtained for particle board with a density target of 0.4 g/cm3 and 0.6 g/cm3 successively include the density with average value of 0.52 g/cm3 and 0.68 g/cm3, the moisture content with average value of 7.13% and 7.3%, water absorption for two hours with average value of 89.51% and 43.14%, water absorption for 24 hours with average value of 123.92% and 74 , 8%, the thickness swelling for two hours with average value of 23.03% and 24.15%, the thickness swelling for 24 hours with average value value of 29.22% and 34.79%, MOE with average value of 8800.88 kg/cm2 and 19581.12 kg/cm2, MOR with average value of 68.57 kg/cm2 and 153.65 kg/cm2, internal bond with average value of 2.53 kg/cm2 and 4.25 kg/cm2, and screw holding power with average value of 24.45 kg and 39.63 kg.
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Judul: Pemanfaatan Cangkang Kemiri Sunan dan Serutan Kayu sebagai Bahan Papan Partikel
Abstrak: Woods are usually used as a raw material of furniture and other wood-based products. Since technology grows rapidly, wood-based products can be made not directly from whole real wood. They can be made from other wood-like processed materials such as hardboard, insulation board, particle board, plywood, and fiberboard. In this research, shell of Aluerites Trisperma Blanco, in Indonesian known as Kemiri Sunan, and wood shaving was used as raw materials of particle board. The objective of this research are (1) to study the effects of difference of material composition to mechanical, physical, and thermal properties of particle board, and (2) to look for the best composition of shell of kemiri sunan and wood shaving. From the research it can be concluded that difference of material composition affects only water content, swelling, modulus of elasticity, modulus of rupture, and internal bonding of particle board. Density, heat spesific, and conductivity are not affected. The best composition was found to be 25% of shell and 75% of wood shaving. At this composition, board density was 0.78 g/cm3, water content 9.23%, swelling 5.93%, modulus of rupture 77.92 kgf/cm2, modulus of elasticity 8.3x102 kgf/cm2, internal bonding 7.98 kgf/cm2, heat spesific 3.64 kJ/kg.K, and conductivity 0.195 W/m.K.
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Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model