Judul: Perbandingan Mean Residual Life Plot dan Measure of Surprise untuk Menentukan Nilai Ambang Batas
Abstrak: Curah hujan ekstrem dapat mengakibatkan bencana alam seperti banjir dan tanah longsor. Bencana alam tersebut akan menimbulkan kerusakan dan kerugian bagi lingkungan sekitar. Pencegahan terhadap kerusakan akibat bencana alam tersebut dapat dilakukan dengan menduga curah hujan ekstrem. Pendugaan curah hujan ekstrem dilakukan berdasarkan Generalized Pareto Distribution (GPD) yang membutuhkan informasi nilai ambang batas. Nilai ambang batas dapat ditentukan dengan dua metode yaitu Mean Residual Life Plot (MRLP) dan Measure of Surprise (MOS). Tujuan penelitian ini yaitu menentukan dan membandingkan nilai ambang batas dengan MRLP dan MOS. Data yang digunakan adalah data curah hujan dasarian dan bulanan. Hasil penelitian ini menunjukkan prosedur MOS lebih singkat dan mudah daripada prosedur MRLP. Berdasarkan hasil validasi silang, nilai log-likelihood MOS lebih besar daripada nilai log-likelihood MRLP sehingga MOS lebih baik daripada MRLP.
Keyword: GPD, MOS, MRLP, threshold

Judul: Penentuan Ambang Batas Curah Hujan Ekstrim dengan Mean Residual Life dan Threshold Choice (Studi Kasus : Curah Hujan Periode 1977-2010 di Stasiun Pondok Betung)
Abstrak: Rainfall has a high diversity and potentially extreme rainfall which can cause flood. Extreme rainfall information needs to be known early to anticipate the possibility of flooding by determining the threshold value. This threshold value can be determined by the 90th percentile, Mean Residual Life (MRL), and Threshold Choice (TC) based on Generalized Pareto Distribution (GPD). Threshold value in Pondok Betung station is 61 mm, based on daily rainfall data in 1977-2010. In general, the majority of flood events occur when daily rainfall at Pondok Betung station above 61 mm.
Keyword: GPD, MRL, TC

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: