The study explores the optimization of the distribution network for a petrochemical business in Thailand, facing intense competition and market share loss to foreign competitors. Aiming to expand its domestic market, ...
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The study explores the optimization of the distribution network for a petrochemical business in Thailand, facing intense competition and market share loss to foreign competitors. Aiming to expand its domestic market, the business seeks to enhance its distribution network by adding a new distribution center (DC). Given the industry’s environmental impact concerns, the study also focuses on reducing the environmental footprint of its supply chain and logistics activities. Despite extensive research on distribution network optimization, there remains a gap in understanding the integrated approach that simultaneously address economic efficiency, customer responsiveness, and environmental sustainability within the petrochemical sector in Thailand. This research proposes various scenarios for the distribution network, considering candidate DC locations based on current customer distributions, particularly in the Bangkok Metropolitan Area and Laem Chabang (LCB) port, along with potential hinterland arears. The analysis evaluates key performance metrics, including responsiveness, economic efficiency, and environmental impact. The findings indicate that the optimal scenario involves operating two DCs: the existing DC and a new DC in Samut Prakarn Province, significantly improving customer responsiveness. However, the results reveal that cost reduction does not directly correlate with decreased GHG emissions. The study underscores the need for businesses to define clear objectives, such as cost reduction, improved customer service, market expansion, or environmental sustainability, before redesigning distribution networks. A comprehensive evaluation of criteria, including social, opportunities, infrastructure, accessibility, resilience, and cybersecurity, is essential for informed decision-making, leading to improved cost efficiency, customer service, and operational agility.
This paper addresses the problem of designing scheduled route for river liner shipping services with empty container repositioning. Given estimated weekly demands, the goal is to determine ports to be called and the s...
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This paper addresses the problem of designing scheduled route for river liner shipping services with empty container repositioning. Given estimated weekly demands, the goal is to determine ports to be called and the ship schedule, while considering navigational restrictions, in order to maximize a shipping company's profit. In this decision -making process, we propose a novel integrated approach that enables the shipping company to optimize liner service routes and ship schedule simultaneously, taking into account empty container repositioning. Two mixed integerprogrammingmodels, the arc -based model and the node -based model, are established to simulate this problem, and linearization techniques are applied to solve the integrated models. We prove the strict equivalence of the two models and discuss the properties of the optimal solutions. Numerical experiments based on the Yangtze River are conducted to test the applicability of these methods. We find that in the case of unsplittable demands, modeling the shipping of empty containers based on node variables significantly outperforms the approach based on arc variables in terms of computation time and accuracy. Additionally, we provide recommendations to guide the tactical decisions of liner shipping companies.
A cruise company faces three decision problems: at a strategic level, to decide in which maritime area and in which season window to locate each ship of its fleet;at a tactical level, given a ship in a maritime area a...
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A cruise company faces three decision problems: at a strategic level, to decide in which maritime area and in which season window to locate each ship of its fleet;at a tactical level, given a ship in a maritime area and in a season window, to decide which cruises to offer to the customers;at an operational level, to determine the day-by-day itinerary, in terms of transit ports, arrival and departure times and so on. This paper focuses on the tactical level, namely on the Cruise Itineraries Optimal Scheduling (CIOS), aiming at determining a scheduling of cruises with the objective to maximize the revenue provided by a given ship placed in a specified maritime area, in a selected season window, taking into account a number of constraints. In particular, we refer to luxury cruises, implying several additional considerations to be taken into account. We propose an integerlinearprogramming (ILP) model for such a CIOS problem. This model has been experimented by a major luxury cruise company to schedule the itineraries of its fleet in many geographical areas all over the world. A commercial solver has been used to solve the ILP problem. Here we report, as illustrative examples, the results obtained on some of these real instances to show the computational viability of the proposed approach.
Original Equipment Manufacturers (OEM) that assemble multiple durable products are actively engaged in adopting remanufacturing practices. This study addresses the introduction of a new business proposal, which is car...
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Original Equipment Manufacturers (OEM) that assemble multiple durable products are actively engaged in adopting remanufacturing practices. This study addresses the introduction of a new business proposal, which is carrying out remanufacturing of components from acquired returns by an OEM through the set-up of required Reverse Flow Capacities (RFC), which are capacities for dismantling the returns and capacities for remanufacturing various components. Hence, by incorporating the activity on remanufacturing of components, an OEM creates a new cheaper source for obtaining components, in addition to the conventional sources of manufacturing and/or purchasing. The components obtained from any of these three sources can be used to assemble the multiple durable products for satisfying demands. The study refers to this problem as "Multi Products-Component Remanufacturing (MP-CR) problem". Furthermore, it is identified that the incorporation of MP-CR problem has tremendous potential in the Indian automobile sector. With these, this study address two strategic issues and an operation issue for the incorporation of new MP-CR problem to an OEM. The first strategic issue is the determination of RFC that must be set-up. This strategic issue is addressed in synchronize with the operational issue of determining the optimal Inventory & Production Plans (I&PP) for assembling multiple products for a given planning horizon. In addition, once the optimal RFC is determined, the second strategic issue is the determination of optimal period (called as Breakeven Period (BEP)), after which the OEM would reclaim the capital investment for setting-up the optimal RFC. In order to address these three interrelated decisions, a systematic methodology is proposed. In the proposed methodology, first an integer linear programming model is developed for the existing system of the OEM to determine the optimal I&PP. Next, this model is extended to determine the optimal RFC and corresponding optimal I&PP
The Virtual Network Function (VNF) embedding problem is important for service provision in the context of Network Function Virtualisation (NFV). However, this problem is proved to be NP-hard and challenging, and requi...
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The Virtual Network Function (VNF) embedding problem is important for service provision in the context of Network Function Virtualisation (NFV). However, this problem is proved to be NP-hard and challenging, and requires to be explored further. In this study, the authors first formulate it as an integerlinearprogramming (ILP) model for optimal solutions. Then, to compensate for the high running time of solving the ILP model, they propose a heuristic approach which fulfils the embedding process by jointly taking the global network connectivity and the local substrate node capacity into consideration. The simulation on real-world network topologies demonstrates that the proposed approach can provide solutions within 1.7 times of the optimal solution offered by ILP. In addition, the experiments also suggest that the proposed approach can provide up to 2.75 times reduction in the overall cost than the other benchmarks.
Routing and spectrum allocation (RSA) is an important problem in elastic optical networks (EONs). With the increase of network scale and task requests, the imbalance of the network topology becomes more and more promi...
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Routing and spectrum allocation (RSA) is an important problem in elastic optical networks (EONs). With the increase of network scale and task requests, the imbalance of the network topology becomes more and more prominent, causing congestion of some links in the network and even paralysation of the entire network. To tackle this issue, in this paper, we first set up an integer linear programming model for RSA problems in EONs, which minimises the number of used slots, optimises the balance of networks and the burden of KeyLinks (i.e., the links which are easy blocked when large requests comes). Then we design a new routing scheme called dynamically adjusted shortest hop count and minimum rank value first (DSHMRF) to select the candidate routes for each request. Moreover, we propose a new genetic algorithm called direction and distance-based genetic algorithm (DDGA) to look for optimal routes for all requests among the candidate routes. To allocate the spectrum reasonably, we adopt first fit (FF) scheme. Finally, the experiments are conducted on several network topologies of different scales with different request sets and the results indicate that the proposed model is effective and the proposed genetic algorithm is efficient.
This work analyses the complex processes for the development of cruises' itineraries to offer on the market and proposes a mathematical model for determining a new itinerary maximizing revenues, customers satisfac...
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This work analyses the complex processes for the development of cruises' itineraries to offer on the market and proposes a mathematical model for determining a new itinerary maximizing revenues, customers satisfaction, while minimizing operative costs. This work represents one of the first attempt to apply optimization techniques to cruise shipping and has been realized in collaboration with Costa Crociere, a cruise company operating in Europe. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
The traditional distribution planning problem in a supply chain has often been studied mainly with a focus on economic benefits. The growing concern about the effects of anthropogenic pollutions has forced researchers...
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The traditional distribution planning problem in a supply chain has often been studied mainly with a focus on economic benefits. The growing concern about the effects of anthropogenic pollutions has forced researchers and supply chain practitioners to address the socio-environmental concerns. This research study focuses on incorporating the environmental impact on route design problem. In this work, the aim is to integrate both the objectives, namely economic cost and emission cost reduction for a capacitated multi-depot green vehicle routing problem. The proposed models are a significant contribution to the field of research in green vehicle routing problem at the operational level. The formulated integer linear programming model is solved for a set of small scale instances using LINGO solver. A computationally efficient Ant Colony Optimization (ACO) based meta-heuristic is developed for solving both small scale and large scale problem instances in reasonable amount of time. For solving large scale instances, the performance of the proposed ACO based meta-heuristic is improved by integrating it with a variable neighbourhood search.
The factory crane scheduling problem (FCSP) deals with assigning delivery tasks to cranes and then sequencing them, in order to minimize the total completion time for all tasks. In this paper, delivery tasks for requi...
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The factory crane scheduling problem (FCSP) deals with assigning delivery tasks to cranes and then sequencing them, in order to minimize the total completion time for all tasks. In this paper, delivery tasks for required jobs are preemptive allowed at most once before the jobs arrive at exit. The preemptive jobs are temporarily stored in a buffer stack, in which jobs pickup and delivery should be performed under the Last-In-First-Out policy. This feature makes our problem more changeling and interesting. In this paper, FCSP is first formulated as an integerprogrammingmodel. Based on properties of the problem, FCSP is then reformulated with a much tighter bound. After that, several families of valid inequalities are proposed and used within a Branch-and-Cut framework. In addition, preprocessing techniques and separation heuristics are used to improve algorithm efficiency. Computational experiments are carried out on practical data collected from the steel company. The results support both effectiveness and efficiency of the model refinements as well as the Branch-and-Cut algorithm proposed.
In this paper, we propose an integerlinearprogramming (ILP) model for static elevator operation problems. The proposed model is based on hall- and car-calls which correspond to pickup and delivery requests in pickup...
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ISBN:
(纸本)9781479959556
In this paper, we propose an integerlinearprogramming (ILP) model for static elevator operation problems. The proposed model is based on hall- and car-calls which correspond to pickup and delivery requests in pickup-and-delivery problems (PDPs), thus is similar to ILP models for PDPs. The primary difference between those models and the proposed model is the prevention of the reverse run, which means that an elevator with a passenger is moved to the direction opposite to that of the passenger. In computer illustrations, the proposed model is roughly investigated by being compared with a trip-based ILP model which has been proposed by the authors.
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