Judul: Penggunaan Metode Perturbasi Homotopi pada Masalah Gelombang Rossby yang Melibatkan Gaya Coriolis
Abstrak: Masalah gelombang Rossby yang melibatkan gaya coriolis merupakan salah satu masalah gelombang yang sering muncul di daerah khatulistiwa dan model matematikanya berbentuk persamaan diferensial tak linear. Salah satu model matematika yang menjelaskan masalah gelombang Rossby adalah persamaan Zakharov-Kuznetsov(ZK)-Burgers. Persamaan ZK-Burgers diselesaikan dengan metode perturbasi homotopi. Penyelesaian menggunakan metode perturbasi homotopi dinyatakan dalam bentuk deret pangkat. Hasil penelitian menunjukkan bahwa galat relatif antara penyelesaian menggunakan metode perturbasi homotopi dan penyelesaian eksak dari model masalah gelombang Rossby relatif kecil. Selain itu, diperoleh bahwa amplitudo gelombang mengalami penurunan pada saat perambatan.
Keyword: gelombang Rossby, persamaan Zakharov-Kuznetsov-Burgers, metode perturbasi homotopi

Judul: Penyelesaian Masalah Gelombang Permukaan dengan Menggunakan Metode Perturbasi Homotopi
Abstrak: Surface wave is a phenomenon that is encountered at the sea surface. Generally, the motion of surface waves in three dimensions could be described mathematically in the form of Kadomtsev-Petviashvili (KP) equation. Kadomtsev-Petviashvili equation is solved using the homotopy perturbation method. In this method, the solution of the KP equation is assumed in the form of power series with the first term of the solution as the initial approach. The solution to the KP equation is studied using two initial approaches. Those are solitary wave solution and solutions in the form of rational functions. The solution of homotopy perturbation method is closed to the exact solution given by Drazin and Johnson (1989).
Keyword: 

Judul: Synthesis of Apatite - Chitosan Composite Using Duck Eggshell and Chitosan with Temperature and pH Control
Abstrak: Composite of apatite-chitosan was prepared by using chitosan as polymer matrix. Calcium phosphate was prepared from CaO and (NH4)2HPO4, which the ratio Ca : P had to be 1.67. Chitosan is produced by deacetilase from biopolymer chitin. Duck eggshell (95% CaCO3) as starting material was converted to be calcium oxide (CaO) through calcinations with temperature 1000oC for 5 hours. In-situ and ex-situ methods were prepared from apatite and chitosan (dissolved with acetate acid 2%). Calcium phosphate prepared for bone implantation, but it is too fragile and brittle to be implant into the body. So addition of chitosan can decrease crystalinity and increase mechanic characteristic (tougher). Composite apatite-chitosan was resulted by fast precipitation. Fast precipitation was held in a breaker glass with nitrogen atmosphere, under controlled temperature at 37oC and pH 7, in order to increase amount of hydroxyapatite. Precipitation with CaO which was dropped by (NH4)2HPO4. Hydroxyapatite and chitosan were appearing at samples with in-situ and ex-situ methods which indicating by peak matching of XRD (closed lattice parameter, crystal size), overlapping at FTIR spectra and supporting by SEM picture (homogenous and agglomerated particle). However, it still needs further research to examine biocompatibility osteoconductive degree of sample by in-vivo and in-vitro test.
Keyword: