Search results for "Operation"
showing 10 items of 2969 documents
The min-max close-enough arc routing problem
2022
Abstract Here we introduce the Min-Max Close-Enough Arc Routing Problem, where a fleet of vehicles must serve a set of customers while trying to balance the length of the routes. The vehicles do not need to visit the customers, since they can serve them from a distance by traversing arcs that are “close enough” to the customers. We present two formulations of the problem and propose a branch-and-cut and a branch-and-price algorithm based on the respective formulations. A heuristic algorithm used to provide good upper bounds to the exact procedures is also presented. Extensive computational experiments to compare the performance of the algorithms are carried out.
Manager's Toolbox for OSS/BSS Market Analysis
2009
The purpose of this section is to provide a set of quick tools for analysts and managers to analyze the status of the telecom operator software market.
Heuristics for the bi-objective path dissimilarity problem
2009
In this paper the path dissimilarity problem is considered. The problem has previously been studied within several contexts, the most popular of which is motivated by the need to select transportation routes for hazardous materials. The aim of this paper is to formally introduce the problem as a bi-objective optimization problem, in which a single solution consists of a set of p different paths, and two conflicting objectives arise, on one hand the average length of the paths must be kept low, and on the other hand the dissimilarity among the paths in the set should be kept high. Previous methods are reviewed and adapted to this bi-objective problem, thus we can compare the methods using th…
Comparing multicriteria methods in the context of environmental problems
1998
Abstract The present paper gives an analysis of the use of ELECTRE III, PROMETHEE I, II, and SMART decision-aids in the context of four different real applications to environmental problems in Finland. These methods are widely used decision-aids in the real planning processes. The purpose of this study is to define the differences of these methods and the results obtained with them, and in this way also to consider their applicability in aiding environmental decision-making. Furthermore, a comparison of the methods based on a set of randomly generated problems is carried out. The choice in practice will not be easy; PROMETHEE does not differ much from SMART with linear value functions, and …
Certifying feasibility and objective value of linear programs
2012
Abstract We present an algorithm that certifies the feasibility of a linear program and computes a safe bound on its objective value while using rational arithmetic as little as possible. Our approach relies on computing a feasible solution that is as far as possible from satisfying an inequality at equality. To this end, we have to detect the set of inequalities that can only be satisfied at equality. Compared to previous approaches, our algorithm has a much higher success rate.
Building Composite Indicators With Unweighted-TOPSIS
2023
Composite indicators have been widely used in a large number of fields, including innovation and entrepreneurship as a useful tool for conveying summary information about overall performance in a relatively simple way. The construction of composite indicators implies several stages concerning collection of data, selection of criteria and individual indicators, normalization and weighting of criteria and indicators, aggregation, and comparison of overall performance of the alternatives or options. This article aims at contributing to the construction of synthetic indicators by showing with a real example, how the proposed methodology can overcome the problem of the establisment of the decisi…
Cascades and multifilters
2000
Abstract Cascades (trees every element of which is a filter on the set of its successors), and multifilters, maps from cascades, are introduced. Multisequences constitute a special case of multifilters. Applications to convergence and to topology are indicated.
Toward solutions for energy efficiency
2020
Abstract The tariff setting for district heating (DH) services is a hard regulatory procedure. This chapter is devoted to development of the simple but sufficiently accurate methodology for fast and objective evaluation of the actual costs of DH to optimize the regulatory process and to set adequate tariffs on heat production and transmission. The developed methodology is based on the data sets of Latvian DH providers, but the methodological principles are applicable in another area too. Investigation of heat production drivers and following simulation revealed the key performance indicators (KPIs): fuel type and price. By usage of intelligent benchmarking data mining methods and mathematic…
An Optical Technique for Springback Measurement in Axisymmetrical Deep Drawing Operations
2001
Abstract In this paper, a measurement technique based on the shadow moire method has been set up to evaluate the springback phenomenon in deep drawing operations. Two proper coefficients are introduced to quantitatively describe the investigated effect. In particular, the proposed technique is able to acquire the final profile of the drawn parts along one or more lateral contour, once extracted out from the dies, and compare such profile with the ideal one derived from the dies CAD geometry. The proposed technique has been applied to an axisymmetrical deep drawing operation, and, moreover, the influence of the blankholder force level and lubricating conditions has been taken into account. T…
Further Developments and Tests of a Progressive Algorithm for Multiple Criteria Decision Making
1993
P. Korhonen, H. Moskowitz, and J. Wallenius (1986) developed a progressive algorithm and the supporting theory for modeling and solving multiple criteria decision problems with discrete alternatives. A special feature of the algorithm is that it relaxes the usual assumption of a fixed set of available decision alternatives and complete knowledge of a decision maker's (DM's) preference structure or value function. The algorithm is based on progressively sampling the decision space, obtaining preference information from the DM, determining the likelihood of finding possibly/surely better alternatives, and based on this information, continuing the search or terminating it by making the final …