Judul: Masalah Penentuan Rute Kendaraan Antarjemput Roti
Abstrak: Product distribution is one of important activitis for a company. In this paper we discussed a pickup and delivery problem in a company. The objective is to find an optimal route in the framework of vehicle routing problem with pickup and delivery with time windows (VRPPDTW). We provided an illustrative example which describes a pickup and delivery process in a bread company with 1 depot, 10 customers, and 7 units of vehicles. In the first stage we decided the minimum number of vehicles required. Then, in the second stage, we determined the route with minimum cost. LINGO 11.0 is utilized in solving the problem.
Keyword: vehicle routing problem, time windows, pickup and delivery product, optimum

Judul: Vehicle Routing Problem pada Distribusi Sayuran Organik
Abstrak: Pengendalian permasalahan yang terjadi pada distribusi sayuran organik dapat diselesaikan dengan Multiple Trip Vehicle Routing Problem for Multiple Product and Compartments with Time Windows (MTVRPMPCTW) dan diselesaikan dengan salah satu metode eksak, yaitu Integer Linear Programming. Aplikasi model dilakukan terhadap tiga kasus berbeda, pelayanan 5 lokasi dengan rute tunggal, pelayanan 10 lokasi dengan rute majemuk, dan pelayanan 15 lokasi dengan rute majemuk serta adanya time windows yang harus terpenuhi. Pada kasus 10 lokasi dan 15 lokasi, kendaraan yang telah selesai mengantarkan sayuran organik harus kembali ke depot dan dapat melakukan lebih dari satu kali proses distribusi apabila masih terdapat lokasi yang belum dilayani. Setiap lokasi pada seluruh kasus dapat memesan lebih dari satu jenis sayuran organik. Produk yang dikirim akan ditempatkan di kompartemen yang spesifik agar produk tidak saling bercampur. Solusi yang diperoleh berupa rute pendistribusian sayuran organik yang meminimumkan total biaya distribusi, serta semakin bertambahnya lokasi maka semakin bertambah pula waktu komputasi yang diperlukan., The distribution problem of organic vegetables can be solved by the Multiple Trip Vehicle Routing Problem for Multiple Products and Compartments with Time Windows (MTVRPMPCTW) and solved by one exact method, namely Integer Linear Programming. The application of the model is carried out on three different cases, service for 5 locations with a single trip, service for 10 locations with multiple trip, and service for 15 locations with multiple trip and there are time windows that must be met. In the case of 10 locations and 15 locations, vehicles that have finished delivering organic vegetables must return to the depot and can carry out more than one distribution process if there are still locations that have not been served. Each location in all cases can order more than one type of organic vegetable. Products sent will be placed in a specific compartment so that the products do not mix with each other. The solution obtained is in the form of an organic vegetable distribution route that minimizes the total distribution cost, and the more locations, the more computational time required.
Keyword: distribution route, exact method, MTVRPMPCTW, organic vegetables

Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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