1,721,177 research outputs found
Exploring Design Dimensions in Flash-based Mass-memory Devices
Full text linkMission-critical space system applications present several issues: a typical one is the design of a mass-memory device (i.e., a solid- state recorder). This goal could be accomplished by using flash- memories: the exploration of a huge number of parameters and trade-offs is needed. On the one hand flash-memories are nonvolatile, shock-resistant and power-economic, but on the other hand their cost is higher than normal hard disk, the number of erasure cycles is bounded and other different drawbacks have to be considered. In addition space environment presents various issues especially because of radiations: the design of a flash- memory based solid-state recorder implies the exploration of different and quite often contrasting dimensions. No systematic approach has so far been proposed to consider them all as a whole: as a consequence the design of flash-based mass-memory device for space applications is intended to be supported by a novel design environment currently under development and refinemen
FLARE: A design environment for FLASH-based space applications
Full text linkDesigning a mass-memory device (i.e., a solid-state recorder) is one of the typical issues of mission-critical space system applications. Flash-memories could be used for this goal: a huge number of parameters and trade-offs need to be explored. Flash-memories are nonvolatile, shock-resistant and power-economic, but in turn have different drawback: e.g., their cost is higher than normal hard disk and the number of erasure cycles is bounded. Moreover space environment presents various issues especially because of radiations: different and quite often contrasting dimensions need to be explored during the design of a flash-memory based solid-state recorder. No systematic approach has so far been proposed to consider them all as a whole: as a consequence a novel design environment currently under development is aimed at supporting the design of flash-based mass-memory device for space application
Maximizing recyclable materials and user utility in waste collection: a linear-quadratic bilevel optimization approach
No full textIn this paper, we present the problem in which a municipal company operating in the waste management sector willing to encourage users to use differentiated waste collection facilities, designs a utility user function to attain such a goal. The problem is modeled in terms of bilevel optimization where the leader is the municipal firm which aims at maximizing the concurrent fraction of user waste demand thrown in recycling facilities, and the follower are users aiming at maximizing the utility function proposed by the leader. The resulting bilevel model is analysed in terms of stability showing that its optimistic solution value equals the pessimistic solution value. A solution approach is presented. Finally, a computational study shows the effectiveness of our proposal
“Multi-Objective and Multi-Level Optimization: Algorithms and Applications”: Foreword by the Guest Editor
Full text linkDecision making in real-world applications frequently calls for taking into account multiple goals to come up with viable solutions [...
Clustering, location, and allocation in two stage supply chain for waste management: A fractional programming approach
No full textIn this paper, we deal with waste management. Our modelling proposal is to use fractional programming to solve two strategical objectives related to the costs incurred and utility generated in servicing customers when clustering, location, and allocation are performed on the supply chain associated with the considered waste management problem. To the best of our knowledge, this is the first model in the literature acting in these directions. After describing the fractional model and its rationale, we apply a reformulation of the latter in terms of mixed-integer linear programming. Experiments carried out after its implementation reveal that the model is effective in producing high quality solutions for the problem
“Algorithms in Multi-Objective Optimization”: Foreword by the Guest Editor
Full text linkMany real-world optimization problems typically involve multiple (conflicting) objectives [...
Multi-objectives Management in Freight Logistics Systems:Increasing Capacity, Service Level and Safety with Optimisation Algorithms
No full textThe complexity of modern supply chains requires decision makers in logistics to work with a set of efficient (Pareto optimal) solutions, mainly to catch different economic aspects for which one optimal solution related to a single objective function is not able to capture entirely. Motivated by this, and by recent changes in global markets and the availability of new transportation services, Multi-objective Management in Freight Logistics provides a detailed study of freight transportation systems, with a specific focus on multi-objective modeling.
Multi-objective Management in Freight Logistics provides decision makers with new methods and tools to implement multi-objective optimization models in logistics. The book combines theoretical aspects with applications, showing the advantages and the drawbacks of adopting scalarization techniques, and when it is worthwhile to reduce the problem to a goal programming one. The book also shows applications where more than one decision maker evaluates the effectiveness of the logistic system and thus a multilevel programming approach is sought to attain meaningful solutions.
Multi-objective Management in Freight Logistics opens by presenting the general working framework, and with analyses of logistic platforms and intermodality management in large scale transportation systems. This is then followed by a study of multi-objective route planning, based on the application of hazardous material transportation. Additionally, the book examines freight distribution on a smaller scale, as in the case of goods distribution in metropolitan areas. The general approach followed by the text is that of presenting both the network design and the tactical (planning) point of view, providing mathematics, algorithms and related experiments for each problem
Location of differentiated waste collection centers with user cooperation: a bilevel optimization approach
No full textWe focus on the problem of locating differentiated waste collection centers: a municipal firm acts with the goal of locating and installing proper capacities to such facilities with the goal of defining a cooperative behaviour of the users of an urban area, possibly giving economic incentives to the latter in the case they decide to follow a predefined planning on waste recycling. The problem has a hierarchical structure and can be modeled as a bilevel program where the leader decision maker, i.e., the municipal firm, identifies which facilities should be opened along with their capacities minimizing the costs while the follower decision maker acts on behalf of the cooperating users in order to maximize the total utility deriving from delivering wastes to facilities. Besides the mathematical formulation of the problem, we propose a randomized-rounding based heuristic to cope with its solution. Experiments on synthetic instances and a comparison with a known algorithm in the literature are presented to assess the effectiveness of our proposal
Novel bilevel formulations for waste management
No full textIn this paper, we propose two bilevel models to cope with problems concerning waste management. The first formulation stems from a multi-objective version of the problem present in the literature, while the second one improves upon the first by taking into account a theoretical result associated with the first formulation. For both models, we provide the optimistic and the pessimistic versions. We validate these formulations in a case study in the Pathum Thani province in Thailand. Moreover, we compare the results obtained by the bilevel formulation to those obtained by a multi-objective version of the problem. Finally, we provide our thoughts on future applications in this field
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