Judul: Uji Laboratoris Daya Tahan Komposit Serbuk Kayu Plastik Polietilena Berkerapatan Tinggi Setelah Pelunturan Terhadap Serangan Rayap Tanah (Coptotermes Gestroi)
Abstrak: In 1999, economic lost caused by termite attack in Indonesia’s building reached 300 billion and in 2000 was predicted reached Rp 3 trilyun (Nandika et al. 2003). In general, damage in this building caused by soil termite attack of Coptotermes genus. To over take this problem, many efforts has been implemented such as development of composite wood technology by combining wood powder with plastic. It is hoped that this combination can decrease termite attack case. Generally, plastic wood composite is made from wood powder and polyethylene mixture. Implementing leaching procedure, testing endurance to soil termite attack by calculating weight decline and termite mortality after baiting was conducted to know the endurance of high density polyethylene plastic wood powder composite from soil termite (Coptotermes gestroi). The smallest leaching percentage was in mixture of HDPE and acetylated wood powder mixture amount of 0,13 %, acetylation treatment increase weight addition percentage and produce wood with higher hydrofobisity (Hadi et al. 1993), while the highest leaching percentage was in control test sample amount of 2,07 %. This is happened because it is easier for wood component to be dissolve in water. Leaching effect was not significant to the sample weight, which means that HDPE and wood powder is resistance to C. gestroi attack. Plastic became the physical blocker for termites to use wood cellulosa. Termite mortality was increase since the first week until observation to all test sample. Research results showed that the resistance of high density polyethylene plastic wood powder composite to C. gestroi attack was not significantly effected by leaching process. Plastic wood powder composite with of HDPE could increase Pinus ponderosa resistance to C. gestroi attack. Wood powder acetylation treatment to plastic wood powder composite produce better resistance to soil termite attack than the others treatment. Coupling agent treatment gave a very small effect increasing plastic wood powder composite resistance to C. gestroi attack. Treatment by adding 1 % zinc borate to P. ponderosa wood powder produce a good plastic wood powder composite resistance to C. gestroi attack.
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Judul: Ketahanan Delapan Jenis Produk Kayu Komposit terhadap Serangan Rayap Tanah (Coptotermes curvignathus Holmgren)
Abstrak: Wood composite products are potential products which are able to be utilized for structural and non-structural functions. However, wood composite needs resistant to subterranean termites attack because of the climate condition in Indonesia supporting the growth of these termites. The objective of this research was to analyze the resistance of eight wood composite products against subterranean termite. Wood composite products comprised of a medium density fiberboard with and without PVC coating, laminated veneer lumber (LVL), particleboard, corrugated board, plywood, MDF treated with anti termites, and treated rubberwood. Method used in this research was based on modified JIS K 1571-2004. Resistance class of plywood and medium density fiberboard (MDF) treated with anti-termite were classified into the first resistance class, which the weight losses were classified into 3.47% and 2% respectively. Rubber wood treated with boric acid treatment was classified into the second resistance class, where the weight loss of this product was 6.13%. In addition, LVL and particleboard were classified into the fourth resistance class, where the percentage of weight losses were 12.21% and 12.28% respectively. However, corrugated board, MDF with or without PVC linings were the worst (fifth) resistance class, which their weight losses percentage were 26.97%, 19.92%, and 19.80% respectively.
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Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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