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 Change and Resistance of Pine and Jabon Wood Preserved with Imidacloprid againts Subterranean Termites through Graveyard Test
Abstrak: Kayu pinus (Pinus merkusii Jungh. et de Vriese) dan jabon (Anthocephalus cadamba (Roxb) Miq.) termasuk kelas awet V yang rentan terhadap serangan organisme perusak, sehingga ketahanannya perlu ditingkatkan. Penelitian ini bertujuan menganalisis pengaruh bahan pengawet imidakloprid terhadap perubahan warna dan ketahanan kayu pinus dan jabon akibat serangan rayap tanah melalui uji kubur selama satu tahun. Pengawetan kayu menggunakan metode vakum tekan dengan bahan pengawet imidakloprid. Pengujian terdiri dari kerapatan, kadar air, retensi, perubahan warna, kehilangan berat, dan tingkat ketahanan kayu. Pengujian tingkat ketahanan kayu menggunakan standar ASTM D 1758-06 dimodifikasi. Hasil menunjukkan pada semua contoh uji setelah uji kubur terjadi perubahan warna dengan nilai perubahan warna (ΔE*) yang besar dan perubahan warna antar contoh uji satu sama lain tidak berbeda. Nilai retensi kayu pinus lebih rendah dibandingkan kayu jabon. Kayu pinus dan jabon kontrol dengan pengawetan imidakloprid berbeda nyata pada pengujian kerapatan, kadar air, kehilangan berat, dan tingkat ketahanan kayu., Pine (Pinus merkusii Jungh. Et de Vriese) and jabon (Anthocephalus cadamba (Roxb) Miq.) belong to durable class V which are susceptible to attack by destructive organisms, so their resistance need to be increased. This study aims to analyze the effect of imidacloprid as a preservative on discoloration and resistance of pine and jabon wood due to subterranean termite attack through a one-year grave test. The preservation of wood used the vacuum-pressed method with the preservative imidacloprid. The test consists of density, moisture content, retention, discoloration, weight loss, and wood resistance level. The protection level test of wood used the modified ASTM D 1758-06 standard. The results showed that after the grave test, all samples had a color change with a large color change va lue (ΔE*) and the color cha nges (ΔE*) of the samples were not different from one another. The retention value of pine wood is lower than jabon wood. Pine wood and control jabon with imidacloprid preservation were significantly different in tests of density, moisture content, weight loss, and wood protection level.
Keyword: discoloration, imidacloprid, jabon, pine, wood resistance

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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