Judul: Color Change and Resistance of Sengon and Mangium Wood Preserved by Imidacloprid through the Grave Test
Abstrak: Sengon (Falcataria moluccana [L.] Nielsen) dan mangium (Acacia mangium Willd.) merupakan kayu yang memiliki tingkat ketahanan yang rendah terhadap serangan organisme perusak. Ketahanan kayu dapat ditingkatkan dengan bahan pengawet imidakloprid. Penelitian ini bertujuan mengetahui perubahan warna yang terjadi setelah uji kubur 12 bulan dan menganalisis pengaruh pengawetan kayu menggunakan imidakloprid terhadap tingkat ketahanan kayu sengon dan mangium akibat serangan rayap tanah. Pengawetan kayu menggunakan metode vakum-tekan. Pengujian tingkat ketahanan kayu mengacu pada ASTM D 1758-06 yang dimodifikasi. Perubahan warna yang terjadi setelah uji kubur memiliki nilai yang besar. Nilai perubahan warna pada semua perlakuan menunjukkan hasil tidak berbeda nyata. Kadar air pada kondisi kering oven menunjukkan hasil kayu mangium lebih tinggi dari kayu sengon pada kedua perlakuan. Nilai retensi kayu sengon lebih rendah dibandingkan kayu mangium. Pengawetan menggunakan imidakloprid membuat kerapatan kayu menjadi meningkat. Kehilangan berat paling besar yaitu sengon kontrol dan terkecil yaitu mangium imidakloprid. Tingkat ketahanan kayu paling tinggi yaitu mangium imidakloprid dan paling rendah sengon kontrol., Sengon (Falcataria moluccana [L.] Nielsen) and mangium (Acacia mangium Willd.) are woods that have a low level of resistance so they are easily attacked by destructive organisms. The termite resistance of wood can be increased using imidacloprid. This study aims to determine the color change that occurs after the 12 months grave test and to analyze the effect of wood preservation using imidacloprid on the resistance of sengon and mangium woods due to subterranean termite attack. Preservation of wood using the vacuum-pressedmethod. The termite resistance test of wood using the modified ASTM D 1758-06. The color change that occurred after the grave test had a large value. The value of color change in all treatments showed no significant difference. The moisture content in oven dried showed thatmangium wood was higher sengon wood in both treatments. The retention value of sengon wood was lower than mangium wood. Preservation using imidacloprid increased the density of the wood. The biggest weight loss was control sengon and the smallest was mangium imidacloprid. The highest protection level was mangium imidacloprid and the lowest was sengon control.
Keyword: color change, imidacloprid, mangium, sengon, wood preservation

Judul: Color Changes and Resistance of Pinewood and Sengon Impregnated with Furfuryl Alcohol against Subterranean Termites through Graveyard Test
Abstrak: Penelitian ini bertujuan menganalisis perubahan warna yang terjadi serta pengaruh perlakuan impregnasi furfuril alkohol terhadap ketahanan kayu pinus dan kayu sengon dari serangan rayap setelah uji kubur selama 1 tahun. Kayu pinus dan kayu sengon yang telah diimpregnasi dengan furfuril alkohol memiliki penambahan berat berturut-turut sebesar 31,2% dan 79,1%, kerapatan 0,93 g/cm3 dan 0,43 g/cm3, serta kadar air 3,27% dan 2,88%. Setelah dilakukan pengujian kubur, kayu pinus dan kayu sengon mengalami perubahan warna yaitu peningkatan tingkat kecerahan dan memiliki tingkat kehilangan berat secara berturut-turut 4,07% dan 2,09% dengan rata-rata nilai ketahanan untuk kedua jenis tersebut sebesar 9,8. Kayu pinus dan kayu sengon tanpa perlakuan secara berturut-turut memiliki kehilangan berat sebesar 59,02% dan 35,58% dengan rata-rata tingkat ketahanan 4 dan 3,8. Tingkat ketahanan yang tinggi untuk kedua jenis kayu menunjukkan bahwa furfurilasi alkohol dapat meningkatkan ketahanan kayu terhadap serangan rayap tanah., This study aims to analyze the effect of furfuryl alcohol impregnation on color changes and the resistance against subterranean termites of pinewood and sengon after in-ground test for 1 year. Furfurylated pinewood and sengon reach weight percent gain 31.2% and 79.1%, densities 0.93 g/cm3 and 0.43 g/cm3, moisture content 3.27% and 79.1%, respectively. In-ground test caused an increase of lightness on both furfurylated pinewood and sengon. Pinewood and sengon have lost weight 4.07% and 2.09% respectively, with the average resistance level 9.8 on both woods. High resistance score on both woods shows that furfuryl alcohol will increase wood durability against termites.
Keyword: pinewood, sengon, wood resistance, furfuryl alcohol

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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