Judul: Multi-Product Vehicle  Routing Problem dengan Time Windows dan Penerapannya pada Penentuan Rute  Distribusi Buku
Abstrak: Vehicle routing problem (VRP) merupakan suatu permasalahan penentuan rute kendaraan yang bertujuan meminimumkan jarak tempuh atau biaya distribusi. Dalam penerapannya, permasalahan VRP ditemukan pada berbagai perusahaan dengan berbagai kendala, seperti kapasitas kendaraan, jenis dan ukuran barang yang berbeda-beda, serta pelayanan tiap pelanggan sesuai dengan time windows (selang waktu). Dalam penelitian ini akan dibahas masalah penentuan rute distribusi buku pada Percetakan Gema Insani yang terletak di wilayah Jabodetabek. Kendala yang dimiliki perusahaan terkait dengan jenis dan ukuran buku untuk permasalahan time windows pada setiap pelanggan. Permasalahan ini dapat dimodelkan sebagai Multi-Product Vehicle Routing Problem with Time Windows (MPVRPTW). Ukuran masalah yang ada membutuhkan waktu komputasi yang lama. Oleh karenanya, solusi optimal tidak dapat diperoleh. Kondisi ini dapat diatasi dengan menyelesaikan masalah ini melalui dua tahap. Tahap pertama dilakukan pengelompokan node pelanggan ke dalam empat klaster. Klaster dibentuk berdasarkan jarak antar node pelanggan menggunakan metode k-Means dengan bantuan perangkat lunak RStudio 2022. Tahap kedua ditentukan rute distribusi pada masing-masing klaster dengan model MPVRPTW menggunakan bantuan perangkat lunak LINGO 19.0., The vehicle routing problem (VRP) is the problem of determining the vehicle route in order to minimize the distance traveled or distribution costs. In its application, VRP problems are found in various companies with various constraints, such as vehicle capacity, different types and sizes of goods, and service for each customer according to time windows. In this study, we will discuss the problem of determining vehicle routes to distribute books at Gema Insani Printing in the Jabodetabek area. The company's constraints include the types and sizes of books for each customer’s time windows. This problem can be modeled as the Multi Product Vehicle Routing Problem with Time Windows (MPVRPTW). The size of the problem requires a long computation time. Because of that, the optimal solution cannot be obtained. This situation can be overcome by solving this problem in two stages. The first stage is grouping customer points into four clusters. The clusters are formed based on the distance between customer points using the k-Means method with RStudio 2022 software. The second stage is determining the distribution route for each cluster using the MPVRPTW model with LINGO 19.0 software.
Keyword: klaster, cluster, multi product, vehicle routing problem, time windows

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: 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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