Judul: Headway and Velocity Optimization of Buses (A Case Study: Operation of Transjakarta at Corridor 1)
Abstrak: Bus Rapid Transit (BRT) merupakan salah satu solusi masalah transportasi di daerah urban dengan sistem transportasi massal yang canggih dan terjadwal dengan baik. Sistem transportasi massal tersebut menggunakan bus dengan infrastruktur jalan yang khusus. Pada karya ilmiah ini akan dibangun suatu model optimasi untuk menentukan headway dan kecepatan bus yang optimal guna meningkatkan pelayanan kualitas pengoperasian bus. Secara spesifik, fungsi tujuan pada model optimasi yang dibangun adalah meminimumkan rata-rata waktu tunggu penumpang. Model optimasi tersebut merupakan suatu model linear programming dan diselesaikan dengan menggunakan software LINGO versi 11.0. Hasil simulasi untuk kasus pengoperasian Transjakarta koridor 1 menunjukkan bahwa headway yang diperkecil dan kecepatan yang diperbesar akan mengurangi nilai rata-rata waktu tunggu penumpang. Sebaliknya, headway yang diperbesar dan kecepatan yang diperkecil menyebabkan terjadinya peningkatan penumpang yang menunggu pada beberapa shelter
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Judul: Masalah Penentuan Koridor Bus dalam Meminimumkan Biaya Operasional
Abstrak: Population’s mobility in Jakarta is extremely high. This would require adequate public transportation facilities. One of the mass public transportation systems developed in Jakarta is bus rapid transit system, which is better known as busway. Busway is expected to be a public transport that would be able to serve the population’s mobility. Currently, the busway is still subsidized by the government, because the fare is set relatively low (in order to attract people using the busway). Nevertheless, the operational cost is relatively high. This paper presents an optimization model to determine the corridors of the busway to be operated as well as the frequency of the buses at each corridor. This optimization is formulated in order to fulfill the demand of transportation for each pair of origin-destination and, at the same time, to minimize the total operational cost. This problem is formulated as a integer nonlinear programming and solved using Lingo software 11.0.
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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.
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