Judul: Physical and Mechanical Characteristics of Tali Bamboo Sandwich Panel with Variation in Dimensions and Number of Layers of Hexagonal Cells
Abstrak: Bambu dapat dipilih sebagai alternatif material lain seperti kayu solid, beton, dan baja. Penelitian ini bertujuan menganalisis pengaruh dimensi dan jumlah lapisan sel heksagon pada core terhadap sifat fisis dan mekanis panel sandwich. Bahan utama pembuatan panel berukuran 300 mm × 300 mm ini adalah bambu tali dan perekat polivinil asetat. Percobaan faktorial dengan pola rancangan acak lengkap diterapkan dengan dua faktor yaitu dimensi sel (kecil, sedang, dan besar) dan jumlah lapisan sel heksagon (2 lapis, 3 lapis, dan 4 lapis). Evaluasi sifat fisis dan mekanis panel sandwich dibandingkan dengan standar JIS A 5905-2003 untuk papan serat dan standar JIS A 5908-2003 untuk papan partikel. Hasil analisis membuktikan adanya pengaruh kombinasi dimensi sel dan jumlah lapisan sel heksagon pada kerapatan dan kuat tekan panel sandwich. Hasil yang paling optimal diperoleh dari panel sandwich dengan kombinasi sel berdimensi kecil berlapis empat yang menghasilkan nilai kadar air 10,18%; kerapatan 0,42%; kuat tekan 20,88 kg/cm2; MOE tegak lurus serat dan sejajar serat berturut-turut 4246 kg/cm2 dan 7883 kg/cm2; MOR tegak lurus serat dan sejajar serat berturut-turut 53,54 kg/cm2 dan 112,27 kg/cm2; serta internal bond 1,04 kg/cm2., Bamboo can be chosen as an alternative to other materials such as solid wood, concrete, and steel. This study aims to analyze the effect of dimensions and the number of layers of hexagonal cells in the core of sandwich panels on their physical and mechanical properties. The main material for making this 300 mm × 300 mm panel was tali bamboo and polyvinyl acetate adhesive. A factorial experiment with a complete randomized design pattern was applied with two factors namely cell dimension (small, medium, and large) and the number of layers of hexagonal cells (2 layers, 3 layers, and 4 layers). The evaluation of these sandwich panels physical and mechanical properties was compared to the JIS A 5905-2003 standard for fiberboards and the JIS A 5908-2003 standard for particleboards. The results of the analysis proved the effect of a combination of cell dimensions and the number of layers of hexagonal cells on the density and compressive strength of the sandwich panel. The optimum result was obtained from sandwich panels with a combination of small-dimensional and four-layered cells, which resulted in a moisture content of 10,18%; density of 0,42%; compressive strength of 20,88 kg/cm2; MOE in perpendicular and parallel to the grain were 4246 kg/cm2 and 7883 kg/cm2, respectively; while MOR in perpendicular and parallel to the grain were 53,54 kg/cm2 and 112,27 kg/cm2, respectively; and internal bond of 1,04 kg/cm2.
Keyword: mechanical properties, physical properties, sandwich panel, tali bamboo

Judul: Characteristics of Physical and Mechanical Properties with Differences on the Thickness of Core and Skin from Tali Bamboo Sandwich Panels
Abstrak: Kebutuhan kayu yang semakin meningkat ditengah ketersediaannya yang terbatas saat ini, telah mendorong dibutuhkannya suatu bahan alternatif lain pengganti kayu yang memiliki kekuatan yang baik serta melimpah ketersediaannya. Bambu dapat menjadi salah satu alternatif bahan baku pengganti kayu yang dapat digunakan dengan potensi yang berlimpah. Penelitian ini bertujuan untuk menganalisis pengaruh ketebalan skin dan core terhadap sifat fisis dan mekanis panel sandwich bambu tali. Variabel yang diuji terdiri atas 6 variasi pasangan ukuran tebal skin dan core yang berukuran 1 mm dan 18 mm, 2 mm dan 16 mm, 3 mm dan 14 mm, 4 mm dan 12 mm, 5 mm dan 10 mm, serta 6 mm dan 8 mm. Perekat yang digunakan dalam pembuatan panel sandwich ini adalah polyvinyl acetate (PVAc). Pengujian contoh uji yang meliputi sifat fisis dan mekanis panel, masing-masing mengacu pada standar SNI 03-2105-2006. Sifat fisis yang diuji meliputi kadar air, kerapatan, pengembangan tebal, dan daya serap air. Sementara, pengujian sifat mekanis meliputi MOE, MOR, kuat tekan, dan keteguhan rekat. Hasil penelitian menunjukkan kualitas panel yang dibuat belum memenuhi syarat SNI 03-2105-2006 untuk papan partikel, kecuali kadar air dan pengembangan tebal. Panel sandwich tidak mengalami kerusakan baik pada bagian core maupun skin. Kerusakan terjadi pada ikatan garis rekat antar skin dan core. Penggunaan jenis perekat yang lebih kuat namun tetap ramah lingkungan diharapkan dapat memperbaiki karakter panel sandwich yang dihasilkan., The increasing need for wood amidst its current limited availability has prompted the need for an alternative substitute for wood that has good strength and is abundantly available. Bamboo is the one of alternative raw materials that can be used with abundant potential. This study aims to analyze the effect of skin and core thickness on the physical and mechanical properties of tali bamboo sandwich panels. The variables tested consisted of 6 variations of skin and core thickness pairs measuring 1 mm and 18 mm, 2 mm and 16 mm, 3 mm and 14 mm, 4 mm and 12 mm, 5 mm and 10 mm, as well as 6 mm and 8 mm. The adhesive used in making this sandwich panel was polyvinyl acetate (PVAc). The obtained panels were tested for their physical and mechanical properties by referring to the SNI 03-2105-2006 standard. The physical properties tested include water content, density, thickness expansion, and water absorption capacity. Meanwhile, mechanical properties testing includes MOE, MOR, compressive strength, and internal bond. Results revealed that the quality of the panels produced did not meet the SNI 03-2105-2006 requirements for particle board, except for moisture content and thickness swelling. The sandwich panel did not undergo damage to either the core or skin. Damage occurred at the bond line between the skin and core. The use of a stronger but still environmentally friendly type of adhesive is expected to improve the character of sandwich panels production.
Keyword: core thickness, polyvinyl acetate, sandwich panel, skin thickness, tali bamboo

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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