The cost for bunker fuel represents a major part of the daily running costs of liner shipping vessels. The vessels, sailing on a fixed roundtrip of ports, can lift bunker at these ports, having differing and fluctuati...
详细信息
The cost for bunker fuel represents a major part of the daily running costs of liner shipping vessels. The vessels, sailing on a fixed roundtrip of ports, can lift bunker at these ports, having differing and fluctuating prices. The stock of bunker on a vessel is subject to a number of operational constraints such as capacity limits, reserve requirements and sulphur content. Contracts are often used for bunker purchasing, ensuring supply and often giving a discounted price. A contract can supply any vessel in a period and port, and is thus a shared resource between vessels, which must be distributed optimally to reduce overall costs. The Bunker Purchasing with Contracts Problem has been formulated as a mixedinteger programme, which has been Dantzig-Wolfe decomposed. To solve it, a novel column generation algorithm has been developed. The algorithm has been run on a series of real-world instances with up to 500+ vessels and 500+ contracts, and provide near optimal solutions. This makes it possible for a major liner shipping company to plan bunker purchasing on a global level, and provides an efficient tool for assessing new contracts.
This work presents a flexible light simulator designed to reproduce precise conditions of both spectrum and intensity of light. The system consists of a combination of different LEDs defined by an optimized selection ...
详细信息
ISBN:
(纸本)9781509062485
This work presents a flexible light simulator designed to reproduce precise conditions of both spectrum and intensity of light. The system consists of a combination of different LEDs defined by an optimized selection method. Buck converters under current-mode control are used to achieve the independent control of each LED model. Independent control of all light sources allows the possibility to vary intensity and spectral distribution of the light. As an example of application, an LED module is designed and implemented to meet the midday sunlight spectrum.
This paper describes the implementation of Nutmeg, a solver that hybridizes mixedinteger linear programming and constraint programming using the branch-and-cut style of logic-based Benders decomposition known as bran...
详细信息
Directional overcurrent relays are used to protect interconnected power systems and looped distribution systems. Several techniques and formulations have been proposed to solve the directional overcurrent relay proble...
详细信息
ISBN:
(纸本)078039156X
Directional overcurrent relays are used to protect interconnected power systems and looped distribution systems. Several techniques and formulations have been proposed to solve the directional overcurrent relay problem. In this paper, the proposed formulations for relay coordination problem are discussed. The protective relay coordination problem is reformulated to take into account the discrete pickup current values. The directional overcurrent relay coordination problem is formulated as a mixedinteger-programming problem. The problem is solved using the OSL solver of the General Algebraic Modeling System (GAMS).
A Digital Twin (DT) is a set of computational models representing real-time physical objects and processes in a digital world. The increasing adoption of this paradigm by the major industrial equipment vendors to simu...
详细信息
ISBN:
(纸本)9781665412919
A Digital Twin (DT) is a set of computational models representing real-time physical objects and processes in a digital world. The increasing adoption of this paradigm by the major industrial equipment vendors to simulate real-time working conditions and perform smart decision-making, established the Smart Factory Digital Twins architectures, where a set of DTs published as microservices interact with each other exchanging information by streaming technology. In this sense, a fundamental problem consists of selecting adequate computational resources to simulate the physical objects. In an Infrastructure as a Service (IaaS) cloud for DTs, the allocation focuses on distributing the jobs of the set into the virtual machine instances in a way that computational resources demand is satisfied and the cost is minimized In this paper, we propose a set of algorithms based on heuristics, metaheuristics, and mixed integer programming to find low-cost solutions. The performance of algorithms is evaluated using Amazon EC2 instances and DT jobs with randomly generated bandwidth, memory, and processor requirements. The experimental results show that the proposed approaches based on bin packing, genetic algorithms, partition, filtering, set coverage, and branch and bound strategies present a competitive performance in the workload allocation of the computational set of jobs of a DT into an IaaS cloud environment. Our allocation heuristic-based techniques allow considerable cost savings in medium and large periods concerning standard approaches such as local search.
Fast web service selection approach is crucial for seamless and dynamic integration of e-business applications. However, since existing service selection approaches take up a lot of time, this make service selection o...
详细信息
ISBN:
(纸本)9783642240096;9783642240102
Fast web service selection approach is crucial for seamless and dynamic integration of e-business applications. However, since existing service selection approaches take up a lot of time, this make service selection out of time control. In this paper, we propose a fast web service selection (FWSS) approach for service composition system in e-business. In FWSS, only those services that fit to the context of users are valid candidates for the composition. and then mixed integer programming is used to find the most suitable service from above services. Experimental results show that our approach can fast perform service selection for web service composition.
Aiming at the green multi-depot heterogeneous-fleet vehicle routing problem (GMDHFVRP), a mixed integer programming model (MIP) was established to minimize the total cost, and a Lagrange heuristic algorithm incorporat...
详细信息
ISBN:
(纸本)9789819947607;9789819947614
Aiming at the green multi-depot heterogeneous-fleet vehicle routing problem (GMDHFVRP), a mixed integer programming model (MIP) was established to minimize the total cost, and a Lagrange heuristic algorithm incorporated with decomposition strategy (LHA_DS) was proposed to solve it. First, the original problem is decomposed into a number of vehicle sub-problems by relaxing the complex constraints. At the same time, the distance-based K-means clustering method is used to allocate service customer sets for each parking lot, and the surrogate subgradient method is used to solve the sub-problems to update the lagrange multiplier;Secondly, in order to obtain a better initial feasible solution, a repair strategy based on greedy idea is designed to repair the problem relaxation solution to obtain a better solution, and a neighborhood search method to determine the operation order is designed to optimize the feasible solution. Finally, the effectiveness of LHA_DS in solving GMDHFVRP is verified by simulation experiments.
Electricity markets have brought significant benefit to the society. The core of the market clearing system is Security Constrained Unit Commitment (SCUC) and Security Constrained Economic Dispatch (SCED). This paper ...
详细信息
ISBN:
(纸本)9781538677032
Electricity markets have brought significant benefit to the society. The core of the market clearing system is Security Constrained Unit Commitment (SCUC) and Security Constrained Economic Dispatch (SCED). This paper first shares the experience from Midcontinent Independent System Operator (MISO) and GE Grid Solution to improve MISO market clearing software performance to meet the needs of market development and business requirement. It then introduces the research and development on next generation market clearing software, including the ARPA-E project to develop high performance computer based optimization engines, to position RTOs/ISOs for future industry evolution.
Power system unit commitment (UC) is a non-convex NP-complete problem, which is very complex to solve on a large scale. Solution methods for the UC problem have been explored, with Lagrangian relaxation (LR) being one...
详细信息
ISBN:
(纸本)9781479979493
Power system unit commitment (UC) is a non-convex NP-complete problem, which is very complex to solve on a large scale. Solution methods for the UC problem have been explored, with Lagrangian relaxation (LR) being one of the most popular approaches in practice. The significant reduction in numerical solution times of commercial mixed integer programming (MIP) solvers makes transitioning from LR to MIP possible. This paper presents a MIP based two-stage optimization approach for solving the UC problem as well as the energy price. The proposed framework has been implemented using MATLAB and tested on two test power systems.
This paper addresses the integration of process planning and scheduling (IPPS) with sequence dependent setup times for a case from the electrical wires and power cables industry. While the IPPS problem has been a subj...
详细信息
ISBN:
(纸本)9783319181677;9783319181660
This paper addresses the integration of process planning and scheduling (IPPS) with sequence dependent setup times for a case from the electrical wires and power cables industry. While the IPPS problem has been a subject of researchers' attention in recent years, majority of research in this field neglect setup time or assume it as a part of processing time. The objective is to simultaneously select the most feasible process plan and schedule with minimum makespan. The problem is modeled as a mixedinteger linear programming problem and an example is presented to demonstrate the applicability and effectiveness of the proposed modeling approach.
暂无评论