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"This study addresses the hub network design problem considering demand uncertainty and hub congestion effects. The problem is formulated as a two-stage stochastic program with recourse model. The model provides a consistent set of hub locations, while adjusting network configuration in response to different demand realizations. A case study collected from real-world data was used to test the proposed model, and a sensitivity analysis was performed to know how several important parameters affected the solution"

"Global revenue by passenger kilometers over the last ten years has grown at an average of 4.7 percent per year. The high growth of air transport must be offset by equivalent airport investment: perhaps even a doubling of the percentage growth of numbers of passengers. The purpose of this paper is to build a development model for investment in hub-and-spoke airport networks. The methodology developed in this paper uses systems dynamics theory. The benefit of using this approach is that the variables in the model are determined through a systems thinking process; the determination of variables through such a thinking process considers causality between variables dynamically, logically, and realistically within a complex aviation industry system. The simulation model shows that using a system dynamics approach can be used to simulate airport infrastructure investment development in a hub-and-spoke network. One of the subsystems is congestion; the result of simulation of this subsystem yields the behavioral characteristics, which show that a surge in demand (which is then offset by the provision of capacity or capacity enlargement) will eventually become stable, indicated by a lack of lines on the runway side. This means that decreases in congestion will increase passenger demand, and will also enhance potential investment in airport infrastructure."

"ABSTRAKThis research focus on consideration of stochastic demand in deterministic Vehicle Routing Problem with Compartment (VRPC) model. VRPC in this research consider split delivery, multi product, and time windows characteristic. Stochastic demand in this research is handled using scenario-based approach. The demand is modeled by constructing discrete scenarios then implementing it in the deterministic VRPC model. The change of customer demand over time is considered as normal probability distribution. Stochastic VRPC model then solved using robust approach by looking for the highest demand under each scenario to be solve, therefore the solution generated deals with the minimum probability of unmet demand."

"Penelitian tentang model persediaan telah banyak dilakukan dan menjadi solusi bagi perusahaan dalam menghadapi ketidakpastiaan dari permintaan pelanggan. Selain data permintaan yang bersifat stokastik, sering pula ditemukan leadtime kedatangan bahan baku di suatu perusahaan yang bersifat stokastik. Sering kali leadtime yang bersifat stokastik dihitung menjadi leadtime yang tetap untuk menyederhanakan perhitungan dan perancangan model persediaan. Hal ini dapat memicu terjadinya stockout pada kenyataan di lapangan, karena tidak memperhitungkan kejadian leadtime kedatangan bahan baku yang berubah atau tidak tetap seperti yang ditentukan. Sehingga penelitian ini dibuat untuk menganalisis bagaimana pengaruh leadtime yang bersifat stokastik pada performa sistem persediaan di suatu perusahaan manufaktur perusahaan di Indonesia. Penelitian ini menggunakan simulasi Monte Carlo untuk melakukan RNG data berjumlah 5000 periode. Simulasi Monte Carlo dipilih karena data permintaan kebutuhan bahan baku komponen pehiasan tidak mengikuti distribusi normal. Dalam penelitian ini juga akan memakai model persediaan (R,Q) untuk membandingkan total biaya yang dikeluarkan ketika menggunakan model persediaan dengan leadtime stokastik atau menggunakan model persediaan dengan leadtime tetap.

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Research on the inventory model has been done a lot and is a solution for companies in dealing with uncertainty of customer demand. In addition to stochastic demand data, it is often found the lead time for the arrival of raw materials in a company that is stochastic. Often a stochastic leadtime is calculated to be a fixed leadtime to simplify the calculation and design of the inventory model. This can trigger a stockout in reality, because it does not calculate the occurrence of the lead time for the arrival of raw materials that changes or does not remain as determined. So this research was made to analyze how the effect of stochastic leadtime on the performance of the inventory system in a manufacturing company in Indonesia. This study uses a Monte Carlo simulation to perform RNG data totaling 5000 periods. The Monte Carlo simulation was chosen because the data on the demand for the raw material requirements of the decking components did not follow a normal distribution. In this study, we will also use the inventory model (R, Q) to compare the total costs incurred when using an inventory model with stochastic leadtime or using an inventory model with a fixed leadtime."

"Aktivitas logistik merupakan salah satu bagian dari rantai pasok supply chain yang sedang menjadi perhatian dibanyak negara, salah satunya Indonesia. Di Indonesia biaya logistik masih terhitung tinggi, dikarenakan adanya ketidakseimbangan aliran distribusi barang di Indonesia bagian Barat dengan bagian Timur. Saat ini pemerintah Indonesia sedang dalam proses untuk mempersiapkan pembangunan pelabuhan peti kemas strategis untuk menyeimbangkan permasalahan anatara Indonesia Timur dengan Indonesia Barat. Dilihat dari konsep perencanaan tersebut maka dalam penelitian tersebut akan mencari alternatif model matematika untuk mencari rute yang optimal dengan fungsi tujuan meminimumkan biaya. Dari model matematika tersebut didapatkan rute yang menghubungkan dari Indonesia bagian barat dengan Indonesia bagian timur.

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Logistic is a part of supply chain that is being addressed in many countries, including Indonesia. The costly logistic of Indonesia is caused by imbalance trading between western and eastern regions in Indonesia. Challenging conditions come to the stakeholders particularly in the logistics sector. In this regard, the Government also plans to develop strategic container terminal ports. Concept of the planning in this research would also search for alternative a mathematics model to minimize logistics cost. From the model mathematics were obtained the route join the west Indonesia with eastern Indonesia."

"Tol Laut adalah program pemerintah yang bertujuan menjadikan Indonesia sebagai poros maritim dunia, dengan cara meningkatkan kapasitas ekonomi nasional dan menurunkan disparitas ekonomi antar daerah. Mulai 2021 pembuatan jaringan berdasarkan hub and spoke mulai dilakukan oleh pemerintah dengan tujuan mengurangi biaya total dengan memanfaatkan economies of scale. Penelitian ini dilakukan untuk membuat design jaringan yang optimal dalam segi total biaya pengiriman dengan memanfaatkan genetika algoritma, pada penilitian ini terdapat dua kasus yang dinyatakan dalam bentuk model hub and spoke yaitu model tipe single allocation model dan model dengan hub tier satu dan hub tier dua. Pada kedua model tersebut dilakukan perhitungan dimana dipertimbangkan faktor diskon dengan yang tidak, kemudian perbandingan hasil biaya pelayaran dari kedua kasus tersebut dilakukan. Hasil penelitian ini memberikan desain jaringan dengan biaya pengiriman terminimum pada kedua kasus.

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The Sea Highway is a government program that aims to make Indonesia the world's maritime axis, by increasing national economic capacity and reducing economic disparities between regions. Starting in 2021, the government will start making networks based on hub and spokes with the aim of reducing total costs by taking advantage of economies of scale. This research was conducted to create an optimal network design in terms of total shipping costs by utilizing genetic algorithms, in this study there are two cases expressed in the form of a hub and spoke model, namely the single allocation model and the model with tier one hub and tier two hub. In both models, a calculation is carried out with and without the discount factor, then the results of the shipping costs from the two cases are compared. The results of this study provide a network design with the minimum shipping cost for both cases."

"The thesis deals with averaging dynamics in a multiagent networked system, which is a main mechanism for diffusing the information over such networks. It arises in a wide range of applications in engineered physical networks (such as mobile communication and sensor networks), as well as social and economic networks. The thesis provides in depth study of stability and other phenomena characterizing the limiting behavior of both deterministic and random averaging dynamics. By developing new concepts, and using the tools from dynamic system theory and non-negative matrix theory, several novel fundamental results are rigorously developed. These contribute significantly to our understanding of averaging dynamics as well as to non-negative random matrix theory."

"Pemerintah Republik Indonesia telah mendorong penggunaan biodiesel B30 pada tahun 2020 dengan penetapan Peraturan Menteri Energi dan Sumber Daya Mineral Republik Indonesia No. 12 Tahun 2015. Hal ini berimplikasi pada peningkatan pengadopsian biodiesel di berbagai sektor. Untuk membentuk biodiesel B30, Fatty Acid Methyl Ester (FAME) digunakan sebagai bahan pencampur minyak solar dengan proporsi 30% untuk FAME dan 70% untuk minyak solar. Namun, perlu adanya perhatian lebih mengenai kendala yang dialami dalam proses distribusi FAME seperti jumlah titik serah yang turut meningkat seiring dengan volume pemanfaatan biodiesel yang meningkat dan banyaknya opsi pola pemenuhan kebutuhan FAME. Skema distribusi FAME yang dilakukan di Indonesia saat ini berbasis pada jaringan point-to-point atau pengiriman langsung dari titik suplai menuju ke titik serah. Dalam penelitian ini, penulis mencoba menggunakan jenis jaringan lain yaitu hub-and-spoke dengan menugaskan sejumlah titik suplai atau titik serah untuk menjadi sarana penerimaan, penyimpanan dan penyaluran FAME bagi daerah sekitarnya. Hasil dari optimasi yang dilakukan menunjukan bahwa terdapat trade off antara kedua tipe jaringan distribusi. Skenario point-to-point memiliki biaya distribusi 35% lebih rendah jika dibandingkan dengan skenario hub-and-spoke. Namun, skenario hub-and-spoke memiliki lead time 24% lebih rendah jika dibandingkan dengan skenario point-to-point

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.The Government of the Republic of Indonesia has encouraged the use of B30 biodiesel in 2020 with the stipulation of Regulation of the Minister of Energy and Mineral Resources of the Republic of Indonesia No. 12 of 2015. This has implications for increasing biodiesel adoption in various sectors. To form biodiesel B30, Fatty Acid Methyl Ester (FAME) is used as a mixing material for diesel oil with a proportion of 30% for FAME and 70% for diesel oil. However, it is necessary to pay more attention to the constraints experienced in the FAME distribution process, such as the number of delivery points which also increases along with the increasing volume of biodiesel utilization and the many options for fulfilling FAME needs. The current FAME distribution scheme in Indonesia is based on a point-to-point network or direct delivery from the supply point to the delivery point. In this study, the researcher tries to use another type of network, namely hub-and-spoke by assigning several supply points or delivery points to be a means of receiving, storing, and distributing FAME for the surrounding area. The results of the optimization carried out show that there is a trade off between the two types of distribution networks. The point-to-point scenario has 35% lower distribution costs when compared to the hub-and-spoke scenario. However, the hub-and-spoke scenario has a 24% lower lead time when compared to the point-to-point scenario."