Biofuels production has been promoted in the attempt to address global warming and oil dependence concerns. However, the environmental impact of biofuels is a very complex issue and cannot be represents by GHG (greenh...
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Biofuels production has been promoted in the attempt to address global warming and oil dependence concerns. However, the environmental impact of biofuels is a very complex issue and cannot be represents by GHG (greenhouse gas) emissions only (carbon footprint). In particular, water consumption (water footprint) has been recognized as a key issue in renewable fuels production. This paper proposes a multiobjective mixedinteger Liner programming modeling framework to optimize the environmental (i.e., the carbon and water footprints) and economic performances of bioethanol supply chains. Multiechelon, multiperiod, and spatially explicit features are embedded within the formulation to steer decisions and investments through a global approach. The strategic design and planning of corn- and stover-based bioethanol production networks is taken into account. A case study is presented referring to the emerging Italian ethanol production. Results show the effectiveness of mathematical programming-based tools to provide decision makers with a quantitative analysis assessing the economic and environmental performances of different design configurations.
Materials selection is an area where designers can have a significant impact on the sustainable performance of a building. Objective factors such as cost constraints, design considerations, and environmental requireme...
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Materials selection is an area where designers can have a significant impact on the sustainable performance of a building. Objective factors such as cost constraints, design considerations, and environmental requirements can play a role in the selection of materials. However, there may be subjective factors that could also impact the selection and affect the achievement of sustainability goals. In order to help decision makers with the selection of appropriate materials, this study proposes a mixedinteger optimization model that considers objective and subjective factors. Design, budget, and the number of points achieved under the Leadership in Energy and Environmental Design (LEED) account for objective factors while subjective factors comprehend user-based perceptions. An instrument further validated through a factor analysis approach is developed to measure perceptions of product sustainability in an attempt to capture subjective factors. To illustrate how objective and subjective factors influence decision making, this paper presents two cases of a building in which materials are selected using the optimization model proposed. (C) 2012 Elsevier Ltd. All rights reserved.
In this paper, we present the derivation of the multiparametric disaggregation technique (MDT) by Teles et al. (J. Glob. Optim., 2011) for solving nonconvex bilinear programs. Both upper and lower bounding formulation...
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In this paper, we present the derivation of the multiparametric disaggregation technique (MDT) by Teles et al. (J. Glob. Optim., 2011) for solving nonconvex bilinear programs. Both upper and lower bounding formulations corresponding to mixed-integerlinear programs are derived using disjunctive programming and exact linearizations, and incorporated into two global optimization algorithms that are used to solve bilinearprogramming problems. The relaxation derived using the MDT is shown to scale much more favorably than the relaxation that relies on piecewise McCormick envelopes, yielding smaller mixed-integer problems and faster solution times for similar optimality gaps. The proposed relaxation also compares well with general global optimization solvers on large problems.
Carbon capture and storage (CCS) involves capturing relatively pure carbon dioxide (CO2) from gaseous combustion products and storing it in various reservoirs. In this work, a multiperiod mixedintegerlinear programm...
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Carbon capture and storage (CCS) involves capturing relatively pure carbon dioxide (CO2) from gaseous combustion products and storing it in various reservoirs. In this work, a multiperiod mixed integer linear programming model focusing primarily on physical and temporal considerations of CO2 sourcesink matching is proposed. CO2 sources are assumed to be characterized by variable flow rates and fixed operating lives;on the other hand, CO2 sinks are characterized by finite injection rate and storage capacity limits, as well as earliest time of availability. The proposed approach takes into account important temporal issues that may be encountered in planning the CCS system, particularly when the operating lives of sources and sinks do not completely overlap. Two illustrative case studies are then solved to illustrate the use of the model to realistic CCS planning problems. (c) 2012 American Institute of Chemical Engineers Environ Prog, 32: 411-416, 2013
In this paper, the problem of minimising maximum completion time on a single batch processing machine is studied. A batch processing is performed on a machine which can simultaneously process several jobs as a batch. ...
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In this paper, the problem of minimising maximum completion time on a single batch processing machine is studied. A batch processing is performed on a machine which can simultaneously process several jobs as a batch. The processing time of a batch is determined by the longest processing time of jobs in the batch. The batch processing machine problem is encountered in many manufacturing systems such as burn-in operations in the semiconductor industry and heat treatment operations in the metalworking industries. Heuristics are developed by iterative decomposition of a mixedintegerprogramming model, modified from the successive knapsack problem by Ghazvini and Dupont (1998, Minimising mean flow times criteria on a single batch processing machine with non-identical jobs sizes. International Journal of Production Economics 55: 273-280) and the waste of batch clustering algorithm by Chen, Du, and Huang (2011, Scheduling a batch processing machine with non-identical job sizes: a clustering perspective. International Journal of Production Research 49 (19): 5755-5778). Experimental results show that the suggested heuristics produce high-quality solutions comparable to those of previous heuristics in a reasonable computation time.
Traditionally centralized manufacturing planning, scheduling, and control mechanisms are being found to be insufficiently flexible to respond to highly dynamic variations in the market requirements. In order to be com...
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Traditionally centralized manufacturing planning, scheduling, and control mechanisms are being found to be insufficiently flexible to respond to highly dynamic variations in the market requirements. In order to be competitive in today's rapidly changing business world, organizations have shifted from a centralized to a decentralized structure in many areas of decision making. Distributed scheduling is an approach that enables local decision makers to create schedules that consider local objectives and constraints within the boundaries of the overall system objectives. In this paper, we assumed that production takes place in several factories, which may be geographically distributed in different locations, in order to take advantage from the trend of globalization. In this approach, the factories that are available to process the jobs have different speeds in which each factory has parallel identical machine. The optimization criterion is the minimization of the maximum completion time or makespan among the factories. After proposing mixed integer linear programming model for the problem, we developed a heuristic and genetic algorithm. For the proposed genetic algorithm, at first, to represent the solutions, we suggested a new encoding scheme, and then proposed a local search based on the theorem developed in the paper. Finally, we compare the obtained solutions using the lower bound developed in this paper. The results show the proposed algorithms to be very efficient for different structures of instances. (C) 2012 Elsevier Inc. All rights reserved.
This note shows that the input targets of proposed model by Kuosmanen and Kazemi Matin (2009) (http://***/10.1016/***.2007.09.040 and http://***/10.1016/***.2008.11.002) may not be less than the input targets of propo...
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This note shows that the input targets of proposed model by Kuosmanen and Kazemi Matin (2009) (http://***/10.1016/***.2007.09.040 and http://***/10.1016/***.2008.11.002) may not be less than the input targets of proposed model by Lozano and Villa (2006) (http://***/10.1016/***.2005.02.031). (C) 2013 Elsevier Ltd. All rights reserved.
The main motivation of this study is to provide, for the first time, a formulation and solution for a class of production scheduling problems (as in cluster tools) characterized mainly by resource collaboration to per...
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The main motivation of this study is to provide, for the first time, a formulation and solution for a class of production scheduling problems (as in cluster tools) characterized mainly by resource collaboration to perform an operation and while allowing batches and considering alternative production methods. We develop a formulation for the new problem and term it a multiple mode per operation, resource collaboration, and constrained scheduling problem (MRCCSP). Some of the important new characteristics we consider are: multiple products (families);multiple orders (jobs) per family;precedence restrictions among the operations that constitute a job;alternative modes for the performance of an operation (each of which needs a set of collaborating resources) may be defined;complementary and exclusive restrictions between operation-modes;batch production is allowed;and setup times may depend on sequence and batch-size. The objective of the MRCCSP is to minimize makespan. We formulate the MRCCSP as a mixed integer linear programming model, and acknowledging the considerable size of the monolithic formulation required, we prescribe a specific method to achieve size reduction. Finally, a customized branch and bound algorithm for optimally solving this problem is proposed and examined experimentally.
The classical implementation of Benders decomposition in some cases results in low density Benders cuts. Covering Cut Bundle (CCB) generation addresses this issue with a novel way generating a bundle of cuts which cou...
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The classical implementation of Benders decomposition in some cases results in low density Benders cuts. Covering Cut Bundle (CCB) generation addresses this issue with a novel way generating a bundle of cuts which could cover more decision variables of the Benders master problem than the classical Benders cut. Our motivation to improve further CCB generation led to a new cut generation strategy. This strategy is referred to as the Maximum Density Cut (MDC) generation strategy. MDC is based on the observation that in some cases CCB generation is computational expensive to cover all decision variables of the master problem than to cover part of them. Thus MDC strategy addresses this issue by generating the cut that involves the rest of the decision variables of the master problem which are not covered in the Benders cut and/or in the CCB. MDC strategy can be applied as a complimentary step to the CCB generation as well as a standalone strategy. In this work the approach is applied to two case studies: the scheduling of crude oil and the scheduling of multi-product, multi-purpose batch plants. In both cases, MDC strategy significant decreases the number of iterations of the Benders decomposition algorithm, leading to improved CPU solution times.
This article presents a mixed integer linear programming model for the problem of operation planning of an electrical distribution system. The model defines the most appropriate adjustment of a set of control variable...
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This article presents a mixed integer linear programming model for the problem of operation planning of an electrical distribution system. The model defines the most appropriate adjustment of a set of control variables to minimize active energy losses of the system. The generation of active and reactive powers of distributed generators, the number of modules in operation of capacitor banks, and the number of tap steps for the voltage regulators are considered as the control variables. In the proposed formulation, the steady-state operation of the electrical distribution network is modeled mathematically, using linear expressions. The use of a mixed-integerlinear model guarantees convergence to optimality using existing optimization software. The model was implemented in the mathematical modeling language AMPL and solved using the commercial solver CPLEX. A test system of 42 nodes was used to show the accuracy of the mathematical model as well as the efficiency of the proposed solution technique.
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