Bilinear theological lubrication mechanics provides an important basis for the designs of re- cently developed electrorheological(ER)'smart'journal bearings and those lubricated by mixed fluid-solid lubri- ***...
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Bilinear theological lubrication mechanics provides an important basis for the designs of re- cently developed electrorheological(ER)'smart'journal bearings and those lubricated by mixed fluid-solid lubri- *** there is not yet a reliable and efficient numerical method for such a problem of non-Newtonian flu- id *** the present paper,a finite element method(FEM)together with mat hematical programming solution is successfully used to solve such a problem.A reliable and generalized numerical method for the designs of electrorheological 'smart' journal bearings and the bearings lubricated by mixed fluid- solid lubri- cant is presented.
In this work, we study the transit network design problem from the perspective of mathematical programming. More precisely, we consider the problem of defining the number and itinerary of bus routes and their frequenc...
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In this work, we study the transit network design problem from the perspective of mathematical programming. More precisely, we consider the problem of defining the number and itinerary of bus routes and their frequencies, for a public transportation system. In this problem, the routes should be defined in terms of a given infrastructure of streets and stops and should cover a given origin-destination demand. The solution (routes and frequencies) should be convenient for the users and the operators. We review existing mathematical programming formulations and propose a new one, paying attention to the following aspects of public transportation systems, that are identified as key elements in order to have a realistic model: (a) the interest of the users, (b) the interest of the operators, (c) the behavior of the users, and (d) constraints regarding transfer, infrastructure and bus capacity. First, we discuss the formulations existing on the literature, in terms of the aspects mentioned above. Second, we propose a mixed integer linear programming (MILP) formulation, that incorporates the waiting time and the existence of multiple lines in the behavior of the users. We validate the proposed formulation using several cases, including a real one. Also, we compare the obtained results against results from the existing literature. In order to include transfer, infrastructure and bus capacity constraints, we propose an extension to the formulation and we discuss its impact in the structure of the model, based on concepts of bi-level mathematical programming. The mathematical formulations developed contribute towards a more realistic modeling effort, taking into account important aspects of the real system which were not included in previous proposals in the literature. (C) 2015 Elsevier Ltd. All rights reserved.
This paper assesses the benefits of cloud federation for cloud providers. Outsourcing and insourcing are explored as means to maximize the revenues of the providers involved in the federation. An exact method using a ...
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This paper assesses the benefits of cloud federation for cloud providers. Outsourcing and insourcing are explored as means to maximize the revenues of the providers involved in the federation. An exact method using a linear integer program is proposed to optimize the partitioning of the incoming workload across the federation members. A pricing model is suggested to enable providers to set their offers dynamically and achieve highest revenues. The conditions leading to highest gains are identified and the benefits of cloud federation are quantified.
There exists little investigation on multiattribute decision making under intuitionistic fuzzy environments although both crisp and fuzzy multiattribute decision making have achieved a great progress. In this paper, m...
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There exists little investigation on multiattribute decision making under intuitionistic fuzzy environments although both crisp and fuzzy multiattribute decision making have achieved a great progress. In this paper, multiattribute decision making problems using intuitionistic fuzzy sets are investigated and the TOPSIS is further extended to develop one new methodology for solving such problems. In this methodology, an interval fractional programming model is constructed on the basis of the relative closeness co-efficient using the TOPSIS. Comprehensive evaluation of each alternative, which may be described as an intuitionistic fuzzy set or interval number, is calculated using two auxiliary mathematical programming problems derived from the interval fractional programming model proposed in this paper. Optimal degrees of membership for alternatives are calculated to determine their ranking order using the concept of likelihood based on the ranking method of interval numbers. Implementation process of the method proposed in this paper is illustrated with a numerical example.
General awareness of the potential of mathematics to support sports decision making has been raised by the movie "Moneyball" through its portrayal of a real professional American baseball club that used math...
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General awareness of the potential of mathematics to support sports decision making has been raised by the movie "Moneyball" through its portrayal of a real professional American baseball club that used mathematical tools to improve team performance. This article addresses the same challenge using as a test case a fantasy sport game organized by an Argentinian newspaper. Two mathematical programming models are presented that act as virtual coaches that choose a virtual team lineup for each round of the real Argentinian soccer league. The a priori design creates a competitive team for the game, while the a posteriori model determines what would have been its optimal lineup once the season is over and all the results are known. The a priori model was entered in the fantasy game, achieving results that positioned it among the highest scoring participants. Further development of such models would provide useful tools for supporting decision making by coaches or managers of real sports.
A flexible formulation for handling a wide range of short-term scheduling problems arising in multi-product/multipurpose batch chemical plants is presented. Time is directly used to model events arising in the schedul...
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A flexible formulation for handling a wide range of short-term scheduling problems arising in multi-product/multipurpose batch chemical plants is presented. Time is directly used to model events arising in the schedule and thus use of binary variables over periods during which no changes in system state occur is avoided. Batch processes involving a variety of operational complexities can be readily represented. The scheduling problem is formulated as a mixed integer nonlinear program (MINLP). The resulting model can be simplified via exact linearization to yield a mixed integer bilinear program (MIBLP) in which the only nonlinearity arises in the objective function as a product of continuous variables. A preliminary computational comparison is made against a uniform time discretization formulation. (C) 1997 Elsevier Science Ltd.
A concept from optimization theory, specifically, mathematical programming, is proposed for designing drugs with desired properties. The mathematical programming formulation is solved to obtain the optimal descriptor ...
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A concept from optimization theory, specifically, mathematical programming, is proposed for designing drugs with desired properties. The mathematical programming formulation is solved to obtain the optimal descriptor values, which are employed in the Cerius(2) modeling environment to infer the optimal lead candidates, in the sense that they exhibit both high selectivity and activity while ensuring low toxicity. It has been observed that unique substituent groups and their molecular conformations are responsible for attaining the goal of simultaneous high selectivity and activity. Both linear and nonlinear quantitative structure activity relationships (QSARs) have been developed for use in the proposed approach. A comparative study of these models is done, and it is shown that the QSARs are well represented by nonlinear models. The proposed mathematical programming strategy has been demonstrated for a class of nonclassical antifolates for Pneumocistis carinii and Tooxplasma gondii dihydofolate reductase. Some of the potential leads found in this study have biological properties similar to those in the open literature. We believe the technique proposed is general and can be applied to other structure based drug design.
One of the approaches to mathematical programming problems solving by means of R-functional modeling is considered. Some functional voxel method tools are presented for the wide class of optimization problems computer...
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One of the approaches to mathematical programming problems solving by means of R-functional modeling is considered. Some functional voxel method tools are presented for the wide class of optimization problems computer solution using voxel algorithm of gradient descent. The illustrative examples of the computer calculations in comparison to non-computer solutions are given.
Many researchers have suggested methods for developing manufacturing cells (machines cells/part families). However, few of these methods have addressed the possible (in actuality, highly probable) existence of excepti...
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Many researchers have suggested methods for developing manufacturing cells (machines cells/part families). However, few of these methods have addressed the possible (in actuality, highly probable) existence of exceptional elements in the solution. Exceptional elements are bottleneck machines and exceptional parts that span two or more manufacturing cells. This paper presents a mathematical programming model that deals with exceptional elements. An initial solution is developed using any of the numerous cell formation procedures. Any exceptional elements that can be eliminated by changing the design or the process plans of the parts are eliminated. Then, the mathematical programming model is solved to determine how best to deal with the remaining exceptional elements. The mathematical programming model considers three important costs: (1) intercellular transfer;(2) machine duplication;and (3) subcontracting. The model is an optimizing model that can recognize possibly advantageous mixed strategies ignored by previous approaches.
mathematical programming can be used for the optimal design of shell-and-tube heat exchangers (STHEs). This paper proposes a mixed integer non-linear programming (MINLP) model for the design of STHEs, following rigoro...
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mathematical programming can be used for the optimal design of shell-and-tube heat exchangers (STHEs). This paper proposes a mixed integer non-linear programming (MINLP) model for the design of STHEs, following rigorously the standards of the Tubular Exchanger Manufacturers Association (TEMA). Bell-Delaware Method is used for the shell-side calculations. This approach produces a large and non-convex model that cannot be solved to global optimality with the current state of the art solvers. Notwithstanding, it is proposed to perform a sequential optimization approach of partial objective targets through the division of the problem into sets of related equations that are easier to solve. For each one of these problems a heuristic objective function is selected based on the physical behavior of the problem. The global optimal solution of the original problem cannot be ensured even in the case in which each of the sub-problems is solved to global optimality, but at least a very good solution is always guaranteed. Three cases extracted from the literature were studied. The results showed that in all cases the values obtained using the proposed MINLP model containing multiple objective functions improved the values presented in the literature. (C) 2013 Elsevier Ltd. All rights reserved.
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