Judul: Pengujian Keawetan Empat Jenis Kayu Tanaman Dengan Standar SNI 01.7207-2006: Tinjauan Terhadap Lama Waktu Pengujian
Abstrak: INTRODUCTION : The use of wood is increasing as human population and technology advancement nowadays. Wood durability is one of wood characteristic. In term of wood durability information, proper wood durabulity testing methode is also important. So a standard of wood durability testing is needed. Wood durability standard available in Indonesia is SNI 01. 7207- 2006. On this standard, the term of testing is tend to be less efficient, which is 6 weeks. So, it is necessary to study furthermore to get more acurate and accountable on testing time. Besides, SNI 01. 7207- 2006 standard does not certainly imlpy the species of wood as a control. This research used four species of wood which are rubber wood, sengon, pine and mangium, and expected to be a species references as a wood control species later. MATERIAL AND METHOD : This reseach used rubber wood (Hevea brasiliensis), pine wood (Pinus merkusii), sengon wood (Paraserianthes falcataria), mangium wood (Acacia mangium) and termites (Coptotermes curvignathus Holmgren). The objective is to evaluate wood durability testing methode of termite attack on SNI 01. 7207- 2006 standard, specific on testing time and the best species of wood as a control. The indicator on this research are weight loss, termites mortality and feeding rate. RESULT AND DISCUSSION : The feeding time was executed by 3 weeks, 4 weeks, 5 weeks and 6 weeks. The result shows that weight loss for 3 and 4 weeks rather similar, and also for 4 and 5 weeks feeding time. Whereas, for 6 weeks feeding time quite different with others. Sengon is the bigest rate of weight loss based on the result, which include in level V of durability. Followed by rubber wood in level IV, mangium in level IV and so with pine wood in level IV. From the results it is known that the feeding time of 4 weeks is the most effective time and the wood that could potentially be used as a control timber is wood sengon. Mortality value for all species is high. This is estimated by environment factor, mostly humidity and temperature. The humidity changes affecting on termites activity. The highest feeding rate on third, fourth, fifth and sixth week found in rubber wood species, the lowest feeding rate found in sengon wood species.
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Judul: Perbandingan standar pengujian keawetan kayu terhadap serangan rayap tanah skala laboratorium (SNI 01.7207-2006 dan JIS K 1571-2004)
Abstrak: Lebih kurang 90% dari 4000 jenis kayu yang dimiliki oleh Indonesia belum diketahui sifat dan kegunaannya (Mandang dan Pandit 1997). Oleh karena itu diperlukan standar pengujian untuk mengetahui sifat-sifat kayu tersebut, salah satunya adalah sifat keawetan kayu. Standar pengujian keawetan kayu yang digunakan di Indonesia adalah SNI 01.7207-2006. Tahapan prosedur dalam standar pengujian ini kurang jelas dan bersifat umum. Ketidakjelasan tahapan prosedur dalam standar ini memungkinkan terjadinya kesalahan pemahaman dan pelaksanaan pada saat pengujian sehingga data yang dihasilkan tidak benar. Di lain pihak, standar pengujian keawetan kayu yang dimiliki oleh Jepang (JIS K 1571-2004) mudah untuk dipahami karena instruksinya lebih jelas dan terdapat nilai standar untuk mengetahui tingkat keberhasilan pengujian. Penelitian ini menggunakan kayu Karet (Hevea brasiliensis Muell. Arg.), kayu Sugi (Cryptomeria japonica (L.f) D. Don), dan rayap tanah (Coptotermes curvignathus Holmgren). Tujuan penelitian ini adalah mengevaluasi standar SNI 01.7207-2006 dengan cara membandingkannya dengan standar JIS K 1571-2004, mengetahui kekurangan standar SNI 01.7207-2006, serta memberikan saran-saran untuk memperbaiki kualitas standar SNI 01.7207-2006. Parameter pembanding antara kedua standar pengujian ini adalah nilai kehilangan berat kayu, mortalitas rayap, dan feeding rate rayap. Nilai kehilangan berat kayu, mortalitas rayap, dan kemampuan makan rayap secara berurut pada pengujian keawetan kayu terhadap serangan rayap tanah yang menggunakan metode SNI 01.7207-2006 dengan contoh uji kayu Karet adalah sebesar 28,23%, 94,30%, dan 0,48 mg/ekor/minggu; dan pada metode JIS K 1571-2004 dengan contoh uji kayu Sugi adalah sebesar 16,75%, 74,93%, dan 0,42 mg/ekor/minggu. Hasil pengujian menunjukkan bahwa setelah dilakukan perbaikan terhadap instruksi pengujian standar SNI 01.7207-2006, nilai kehilangan berat contoh uji kayu yang diperoleh dapat dijadikan sebagai dasar penetapan kelas awet kayu. Berdasarkan nilai rata-rata kehilangan berat contoh uji kayu pada pengujian, maka kayu Karet termasuk kelas awet V dan Kayu Sugi termasuk kelas awet IV terhadap serangan rayap tanah. Nilai tersebut sesuai dengan literatur kelas awet masing-masing kayu. Nilai mortalitas dan kemampuan makan rayap kedua metode pengujian tidak jauh berbeda, tetapi nilai kehilangan beratnya berbeda nyata. Perbedaan ini diduga dipengaruhi oleh jenis dan volume contoh uji kayu, jenis media uji, jumlah rayap uji, komposisi kasta rayap uji, serta lama waktu pengujian. Tahapan prosedur mengenai komposisi kasta rayap, ukuran botol uji, kadar air media, tahapan persiapan contoh uji, dan rumus kehilangan berat yang dilakukan pada penelitian ini dapat menjadi masukan untuk memperbaiki kualitas standar pengujian SNI 01.7207-2006.
Keyword: Keawetan kayu, Rayap tanah, Standar pengujian, SNI 01.7207-2006, JIS K 1571-2004, Bogor Agricultural University

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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