In this paper, we propose a new mathematical programming model for integrating production and procurement transport planning decisions in manufacturing systems in a unique optimization model. This problem was introduc...
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In this paper, we propose a new mathematical programming model for integrating production and procurement transport planning decisions in manufacturing systems in a unique optimization model. This problem was introduced conceptually and dubbed as MRP IV by Diaz-Madrofiero et al. (2012) to extend the current MRP (material requirement planning) systems. This proposal simultaneously considers material, production resources capacities and procurement transport planning decisions with different shipping modes (such as full truckload, less-than-truckload and milk-run) in the supply chain to avoid suboptimal results, which are usually generated due to sequential and independent plans. We considered an industrial automobile company to validate the proposed model using real world data. The results obtained by the MRP IV proposed model, in terms of total planning costs and transport efficiency indicators, are better than those obtained in the current heuristic procedures followed in the company under study. (C) 2017 Elsevier Inc. All rights reserved.
This study applied mathematical programming approach to investigate the brand efficiency of smartphone brands by collecting data of 2013-2015 from Consumer Report. The brand efficiency was completed by employing the s...
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This study applied mathematical programming approach to investigate the brand efficiency of smartphone brands by collecting data of 2013-2015 from Consumer Report. The brand efficiency was completed by employing the slack-based measure in data envelopment analysis. The degree of inefficiency of each brand was evaluated, and each brand's metatechnology ratio was calculated using the metafrontier concept. The results revealed that the sampled smartphone brands reach the highest average brand efficiency in 2013, where Apple exhibited the highest brand efficiency among the sampled brands. The high brand efficiency in 2013 was attributed to the small number of product types at beginning of the growth period of smartphones. Finally, this study examined the efficiency of smartphone brands among four major telecommunications operators in the United States. It was found that Apple demonstrated the highest efficiency with all four operators, while no significant difference was noted among operators and smartphone brands.
The problem of tuning stabilizers in multimachine power systems has been formulated here as a sequence of optimization problems. Both quadratic and linear programming problems have been considered. In the former case,...
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The problem of tuning stabilizers in multimachine power systems has been formulated here as a sequence of optimization problems. Both quadratic and linear programming problems have been considered. In the former case, stabilizers with complex zeros have been included in the compensator model. In each case a particular measure of the stabilizers' gain has been defined. The constraints have been written to represent the region allowed for eigenvalue shifting together with specific constraints. The objective has been to shift the lightly damped eigenvalues associated to the system electromechanical modes. The results have shown that the quadratic programming formulation may be an important auxiliary tool for stabilizers tuning.
We propose a structural optimisation method, based on the level set method and using mathematical programming such as the method of moving asymptotes (MMA), which we apply to the design of compliant mechanisms. A comp...
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We propose a structural optimisation method, based on the level set method and using mathematical programming such as the method of moving asymptotes (MMA), which we apply to the design of compliant mechanisms. A compliant mechanism is a monolithic joint-free mechanism designed to be flexible to obtain a specified motion. In the design of compliant mechanisms, several requirements such as the direction of the deformation and stress concentrations must be considered to obtain the specified mechanical function. Topology optimisation, the most flexible type of structural optimisation, has been successfully used as a design optimisation method for compliant mechanisms, but the utility of topology optimisation results is often spoiled by a plethora of impractical designs such as structures containing grayscale areas. Level set-based topology optimisation methods are immune to the problem of grayscales since the boundaries of the optimal configuration are implicitly represented using the level set function. The proposed method updates the level set function using mathematical programming to facilitate the treatment of constraint functionals. To verify its capability, we apply our method to compliant mechanism design problems that include displacement constraints and stress constraints.
A method is proposed that uses operations research techniques to optimize the routes of waste collection vehicles servicing dumpster or skip-type containers. The waste collection problem is reduced to the classic trav...
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A method is proposed that uses operations research techniques to optimize the routes of waste collection vehicles servicing dumpster or skip-type containers. The waste collection problem is reduced to the classic travelling salesman problem, which is then solved using the Concorde solver program. A case study applying the method to the collection system in the southern zone of Buenos Aires is also presented. In addition to the typical minimum distance criterion, the optimization problem incorporates the objective of reducing vehicle wear and tear as measured by the physics concept of mechanical work. The solution approach, employing graph theory and mathematical programming tools, is fully described and the data correction process is also discussed. The application of the proposed method minimized the distance travelled by each collection vehicle in the areas studied, with actual reductions ranging from 10 to 40% of the existing routes. The shortened distances led in turn to substantial decreases in work done and therefore in vehicle wear and tear. Extrapolation of the results to the entire southern zone of Buenos Aires indicates potential savings for the civic authorities of more than US$200 000 per year in addition to the qualitative impacts of less traffic disruption, less vehicle driver fatigue and less pollution.
Intelligent planning for inspection of parts with complex geometric surfaces using contact or non-contact devices is still a major challenge. Contact measurement is widely used in manufacturing owing to its superiorit...
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Intelligent planning for inspection of parts with complex geometric surfaces using contact or non-contact devices is still a major challenge. Contact measurement is widely used in manufacturing owing to its superiority in point accuracy. However, the volumetric accuracy of non-contact measurement techniques is better owing to the large number of points that can be measured in a short time. Consequently, contact measurement is usually used for mechanical parts with prismatic shapes while non-contact measurement methods are mostly used with free-form shapes. Complex parts that include both prismatic and free form shapes may require inspection using both techniques. It may not be possible to fully digitise a part using a single type of sensor owing to occlusion or accessibility issues. This paper proposes a hybrid (contact/non-contact) inspection planning approach that capitalises on the advantages of both inspection techniques. In the beginning, a knowledge-based system has been developed for selecting the most suitable sensor for the inspected features using a proposed inspection-specific features taxonomy. Additionally, a new travel salesperson problem (TSP) formulation has been developed for sequencing of hybrid inspection tasks, where a novel sub-tour elimination constraint has been formulated. The proposed 0-1 integer mathematical model minimises the non-digitisation related time between successive inspection operations. The developed hybrid inspection planning system not only overcomes the incompleteness of information when each sensor type is used separately, but also improves the accuracy of the point cloud obtained by using both sensors. The developed hybrid inspection planner was applied to the inspection of a water pump housing of an automotive engine. The applicability of the developed inspection planning framework and methodology for inspecting complex parts and associated dies and moulds has been demonstrated. The developed system makes it easier to util
This paper presents a hybrid genetic algorithm/mathematical programming heuristic for the n-job, m-machine flowshop problems with lot streaming. The number of sublots for each job and the size of sublots are directly ...
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This paper presents a hybrid genetic algorithm/mathematical programming heuristic for the n-job, m-machine flowshop problems with lot streaming. The number of sublots for each job and the size of sublots are directly addressed by the heuristic and setups may be sequence-dependent. A new aspect of the problem, the interleaving of sublots from different jobs in the processing sequence, is developed and addressed. Computational results from 12 randomly generated test sets of 24 problems each are presented. (C) 2006 Elsevier Ltd. All rights reserved.
In a dynamic manufacturing environment, manufacturing cell configurations based on current part mix and production process may need to be revised once the part mix or the production process has changed. However, machi...
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In a dynamic manufacturing environment, manufacturing cell configurations based on current part mix and production process may need to be revised once the part mix or the production process has changed. However, machine and equipment moving costs make frequent reconfiguration uneconomical and sometimes impossible. Designing a sustainable cellular manufacturing system in a dynamic environment is studied in this paper. An integer programming model is developed to minimize material handling and machine costs as well as cell reconfiguration cost for a planning horizon of multiple time periods. Solving this integer programming problem is NP-complete. A decomposition approach is developed so that the decomposed subproblems can be solved with less computational effort. Dynamic programming is then employed to find a solution of the original problem. Numerical examples are presented to illustrate the model and the solution technique developed in this paper.
Solution of steady-state scalar conservation laws [f(u)]x + pi[f(u)]y = 0 (tau-constant) on the unit square is considered for the two cases f(u) = u and u2. Piecewise constant Dirichlet conditions producing shocked so...
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Solution of steady-state scalar conservation laws [f(u)]x + pi[f(u)]y = 0 (tau-constant) on the unit square is considered for the two cases f(u) = u and u2. Piecewise constant Dirichlet conditions producing shocked solutions are given on the boundary of the unit square. A nonsingular perturbation 2-epsilon-u (epsilon a sufficiently small positive number), rather than a singular perturbation such as -epsilon(u(xx) + u(yy)), is added to the conservation law. The perturbed equation is discretized in a finite-volume sense on each of the cells of a grid of mm equal rectangular cells (m in the x-direction and n in the y-direction). Numerical values of u are located at the cell vertices. The arclength and area integrals of the finite-volume formulas are discretized by the trapezoidal rule. A system of mn equations results for the (m - 1)(n - 1) unknown values of u in the interior of the domain. This system is solved in the l1 sense;that is, the sum of the absolute values of the residuals of the equations is minimized. An algorithm requiring only O(mn) operations is introduced to solve this mathematical programming problem. The numerical solutions have discontinuities in or near the cells containing the shocks of the physically relevant solutions of the original conservation laws and are O(epsilon) approximations of these solutions. A complete theory for the linear case f(u) = u and computational results for the nonlinear case f(u) = u2 are presented. The l1 procedure captures boundary shocks as well as oblique and even zigzag interior shocks in one cell. The results presented here demonstrate that the l1 procedure is a robust, efficient, and highly accurate numerical procedure for solving certain two-dimensional scalar conservation laws.
作者：
Cottle, RWStanford Univ
Terman Engn Ctr Dept Management Sci & Engn Stanford CA 94305 USA
mathematical programming owes much to George B. Dantzig who passed away on May 13, 2005 at the age of 90. This article is a tribute to this legendary pioneer and a very brief review of his extensive and enduring contr...
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mathematical programming owes much to George B. Dantzig who passed away on May 13, 2005 at the age of 90. This article is a tribute to this legendary pioneer and a very brief review of his extensive and enduring contributions to our field.
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