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: Sifat Fisis-Mekanis Papan Partikel dari Kombinasi Limbah Shaving Kulit Samak dan Tandan Kosong Kelapa Sawit dengan Konsentrasi Perekat Berbeda
Abstrak: Shaving leather waste is the residue of shaving yield which had been tanned wether by plant or chrome tannin. Shaving leather waste of tannin leather which used by plant tannin could be used directly as fertilizer, while if it used more than 2 mg/l or 0,14 kg/ton could be caused soil fertility disturbance and skin illness (BAPEDAL, 1996). According to BAPEDAL (1996) later many tanning leather factories used chrome tanning, since the increasing of market demand toward leather into chrome tannin. The objectives of this research was to use shaving leather waste which usually pile up and interfered the environment and its neighborhood, and to study for other alternative of the present leather tanning waste usage. The result reveals that physical and mechanical properties of particleboard made from shaving leather waste and palm empty bunches conform with SNI standard with hardwood bonded by urea formaldehida. Completely Randomized Design two factor is used in this research. With combinate shaving waste and palm bunch (0:100, 25:75, 50:50, 75:25) as first factor and adhesive concentration such as 6, 8, and 10% as second factor with three time replication. Parameters were board density, moisture content, water absorption, thickness swelling, modulus of rupture, modulus of elasticity, internal bond and wood screw holding power. The data were analyzed ANOVA, and if the significant differences occurred then continued with Polynomial Orthogonal Test. The result showed that shaving combine with palm empty bunches level significantly (P<0.05) affected moisture content, thickness swelling, wood screw holding power, modulus of rupture, modulus of elasticity and internal bond. Adhesives level significantly (P<0.05) the board density, modulus of rupture, modulus of elasticity and internal bond.
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Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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