Judul: Masalah Penjadwalan Kereta Api Jalur Ganda Menggunakan Model Job-Shop
Abstrak: Train scheduling problem can be modeled as a special case of job-shop scheduling problems. Based on the job-shop scheduling concept, the train trip can be considered as a job, which will be scheduled on tracks as resources. In this paper, train scheduling model is formulated under common rules in railroad system, e.g. crossing, overtaking and headway rules. The crossing rule is not implemented for double track, because there are two tracks that can be used by two trains with different directions. The train scheduling model is expressed in the form of integer linear programming and solved by branch and bound algorithm to minimize the total makespan. The model is then implemented for double track case of Mass Rapid Transit (MRT) Lebak Bulus- Sisingamangaraja route, which involves 11 MRT Economy and 7 MRT Express trains using hypothetical data. The train time-space diagrams show that there is no conflicts occurred and the total makespan is 1502 minutes. The result, in particular, indicates that there is an 11 minutes delay for MRT Express. The length of the delay can be reduced by employing an additional delay constraint. But, of course, this will deteriorate the makespan.
Keyword: 

Judul: Masalah Penjadwalan Kereta Secara Periodik dengan Biaya Minimum pada Jalur Ganda
Abstrak: Train scheduling problem is an interesting topic to be discussed, since train has become such an important mass transportation in Indonesia. For that reason, this paper discusses how to solve a minimum cost scheduling problem (MCSP). The train scheduling problem that minimizes operation cost is formulated by MCSP in the form of integer programming. MCSP can be divided into two sections, i.e. minimum cost train problem (MCTP) and scheduling problem. In the first step, the right train is chosen with MCTP for a route, which satisfies a minimum cost. Furthermore, the next step solves the scheduling problem for the chosen train. The schedule is formulated only for one time period, which is assumed periodic. This solution is carried out by LINGO 11.0. The result gives the train scheduling for the specific route, which has minimum operation cost.
Keyword: 

Judul: Phycocyanin Extract From Spirulina platensis for as an Antioxidant and Biopigment for Spherificated Caviar Product
Abstrak: Fikosianin merupakan pigmen alami berwarna biru cerah yang kaya manfaat dengan kandungan antioksidan yang tinggi. Antioksidan memiliki peran yang sangat penting untuk mencegah kerusakan tubuh pada level molekuler yang disebabkan oleh radikal bebas. Radikal bebas dapat mengakibatkan kerusakan DNA, pembelahan sel abnormal (kanker), penuaan dini, inflamasi, penyakit jantung, dan beragam efek negatif lainnya. Pigmen fikosianin tersedia secara melimpah pada Spirulina platensis yang merupakan ganggang hijau biru (mikroalga) yang mudah dikultivasi dan dikondisikan serta dapat tersedia sepanjang tahun. Sebagai pigmen alami, fikosianin cenderung tidak stabil terpapar oksigen, cahaya, suhu, dan pH tertentu. Pemanfaatan pigmen fikosianin harus mampu menjaga kestabilan kandungan bioaktif pigmen dan tetap menarik bagi konsumen. Pengolahan pigmen fikosianin sebagai food additive pewarna pada produk spherificated caviar dapat dilakukan. Spherificated caviar dibuat dengan teknik spherification yang berfungsi sebagai penyalut yang melindungi bahan inti. Tujuan dari penelitian yaitu mempelajari pengaruh penambahan pigmen fikosianin kedalam produk spherificated caviar terhadap stabilitas kandungan antioksidan pigmen serta penerimaan konsumen terhadap produk. Metode yang dilakukan meliputi ekstraksi pigmen fikosianin dengan metode maserasi, kemurnian pigmen, analisis aktivitas antioksidan, dan uji organoleptik. Hasil menunjukan ekstrak pigmen dalam jangkauan warna biru kehijauan, pemurnian ekstrak menghasilkan angka 1,541 dengan kategori food grade. Analisis antioksidan menghasilkan nilai IC50 2,81 untuk ekstrak, dan nilai IC50 10,54 setelah diolah menjadi produk, keduanya termasuk kedalam kategori antioksidan kuat. Variasi konsentrasi pigmen fikosianin tidak memberi perbedaan nyata terhadap penerimaan konsumen dalam atribut warna, rasa, dan tekstur produk. Kata kunci: antioksidan, fikosianin, pigmen, spherificated caviar, Spirulina platensis, Phycocyanin is a bright blue natural pigment that has great beneficial and rich in antioxidant content. Antioxidant has an important role in preventing molecular damage on the body that is caused by free radicals. Free radicals could cause DNA damage, abnormal cell growth (cancer), premature aging, inflammation, heart diseases, and other negative effects. Phycocyanin pigment is found abundance in Spirulina platensis which is a blue green algae (microalgae) that is easy to cultivated and conditioned, also able to produce throughout the year. As a natural pigment, phycocyanin is prone to be unstable when exposed to oxygen, light, and to a certain temperature and pH. The utilization of phycocyanin pigment as colorant food additive in spherificated caviar product could be considered. Spherificated caviar is made with spherification technique that acts as coat / encapsulating that protects the main substance. The objective of this research is to study the effect of adding phycocyanin pigment into spherificated caviar product and also consumer preference of the product. Methods that are used including phycocyanin extractions with maceration method, phycocyanin pigment purity ratio, antioxidant activity analysis, and organoleptic test. The result shows phycocyanin pigment extraction produce bluish green colour, phycocyanin purification resulting in 1,541 value which belongs in the food grade category. Antioxidant analysis resulting in IC50 value of 2, 81 for phycocyanin extract, and IC50 value of 10,54 after being processed into spherificated caviar product, both value fall under very strong antioxidant category. Variants of phycocyanin pigment concentration added into the product did not affect consumer preferences in color, taste, and texture of the product. Keywords: antioxidant, phycocyanin, pigment, spherificate caviar, Spirulina platensis
Keyword: antioxidant, phycocyanin, pigment, spherificated caviar, spirulina platensis