Judul: Pengembangan proses ekstraksi gambir (Uncaria gambir)
Abstrak: Tujuan dari penelitian ini adalah untuk mendapatkan gambaran lebih jelas mengenai imdustri pengolahan gambir secara tradisional, serta mengambangkan proses industri yang lebih baik berdasarkan proses tradisional tersebut. Pengolahan gambir tradisional di Sumatera Barat khususnya di Tanjung Balit, masih sangat sederhana dan cara kerjanya tidak nyaman. Produktivitas pengolahannya kecil, walaupun mutunya baik. Proses ekstraksi mekanis dengan penirisan pada suhu ruang menghasilkan gambir dengan karakteristik terbaik, jika dibandingkan dengan proses ekstraksi menggunakan pelarutan. Proses ekstraksi mekanis merupakan pengembangan dari proses tradisional yang dilaksanakan di Tanjung Balit, Sumatera Barat. Perbaikan mutu gambir dapat dilaksanakan di Indonesia, dengan teknologi yang dapat dikembang- kan di Indonesia.
Keyword: Ekstraksi gambir, Uncaria gambir

Judul: Studi pemanfaatan gambir (Uncaria gambir Roxb) dalam proses pewarnaan kain mori
Abstrak: Gambier is an extract of leaves and branches of gambier plant (Uncaria gambier Roxb). Gambier is one of Indonesia export commodities mostly produced in Sumatera island. Indonesia plays role as the world’s largest gambier exporter. In Indonesia, gambier utilized traditionally as leather tanning material, ingredient of traditional medicine, rust omission, etc. Chemical components of gambier mostly utilized are catechin and tannin. Technology of gambier processing that existed in Indonesia is still low in capacity, so the processing of gambier is mostly done traditionally. This kind of processing resulted on low quality and lack of economical value products of gambier. Therefore, development of processing method and wide utilization of Gambier in industry are needed to increase gambier added value. Tannin and catechin on gambier also can be utilized as colouring agent in textile industry to gain reddish brown colour on batik clothes that will be endure on intense sunlight exposure. Textile industries in Indonesia, especially batik industries, are now developing rapidly where the trend of batik clothes on every occasion is becoming common interest. On technological side, in general the batik industrialists have not done any development on their production sytem and method, so they could be more productive and produce uniformity of product quality. Utilization of natural colouring agent is also not becoming a consideration of most batik industrialists in the environmental issue that is now being widely concerned.
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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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