Ant Methaheuristics with Adapted Personalities for Vehicle Routing Problem

At each generation of an ant algorithm, each ant builds a solution step by step by adding an element to it. Each choice is based on the greedy force (short term profit or heuristic information) and the trail system (central memory which collects information during the search process). Usually, all the ants of the population have the same char- acteristics and behaviors. In contrast in this paper, a new type of ant metaheuristic is proposed. It relies on the use of ants with different per- sonalities. Such a method has been adapted to the well-known vehicle routing problem, and the obtained average results are very encouraging. On one benchmark instance, new best results have been found

Reliability and validity study of the Spanish adaptation of the "Wijma Delivery Expectancy/Experience Questionnaire" (W-DEQ-A)

The Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ-A) is an instrument that evaluates fear of childbirth through the expectations of women in relation to childbirth and their experience during the birth. The objective of this study was to translate the W-DEQ-A into Spanish and analyse its reliability and validity. The study was carried out in two phases: (1) adapting the questionnaire to Spanish and (2) a transversal study in a sample of 273 pregnant women in the Sexual and Reproductive Health centres in the Metropolitan Northern Barcelona in Catalonia (Spain). The psychometric properties were analysed in terms of reliability and construct validity. The confirmatory factorial analysis did not confirm the unidimensionality of the original structure of the WDEQ-A, as happened with the other studies in which it has previously been validated. The result of the exploratory factorial analysis suggests four factors, or dimensions, very similar but not identical to those obtained in other analysis studies of the W-DEQ-A. The Cronbach alpha and the omega scale were also adequate for all the scales and for each of the dimensions. The results of this study confirm the findings of other studies that suggest that the W-DEQ-A is multi-dimensional. In the Spanish version of the W-DEQ-A four dimensions have been identified to explore fear of childbirth in pregnant women. The Spanish version of the WDEQ-A (WDEQ-A-Sp) is reliable and valid for the measurement of fear of childbirth in clinical practice and for use in future research

Validity and reliability of the Spanish version of the "Wijma Delivery Expectancy/Experience Questionnaire" (W-DEQ-B)

The Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ-B) is an instrument that allows the experiences around fear of childbirth to be examined after the birth. It is currently the most widely used to measure different aspects related to the fear of childbirth and enables healthcare and additional assistance to women after birth to be adapted according to their needs. The objective of this study was to translate the W-DEQ-B into Spanish and analyse its reliability and validity. The study was carried out in two phases: (1) transcultural adaption of the questionnaire to Spanish and (2) a transversal study in a sample of 190 postpartum women from Sexual and Reproductive Health Clinics in the province of Barcelona (Spain). The psychometric properties were examined in terms of reliability (internal consistency and temporal stability) and construct validity (confirmatory factorial analysis [CFA] and exploratory factorial analysis [EFA]). The results of the CFA did not confirm unidimensionality of the W-DEQ-B questionnaire. The EFA suggested four very similar, but not identical, dimensions to those obtained in other studies in which the W-DEQ-B has been evaluated. Both the Cronbach's alpha and the omega coefficient were adequate for the total questionnaire and for each of the four dimensions. The results of this study confirm that the W-DEQ-B is multi-dimensional. In the Spanish version of the W-DEQ-B-Sp four dimensions have been identified that allow the experiences around fear of childbirth to be examined after the birth. The Spanish version of the WDEQ-B (WDEQ-B-Sp) is reliable and valid for the measurement of fear of childbirth in clinical practice and for use in future research

Unconventional ant algorithms for vehicle routing

The algorithm developed in this work differs strongly from the other Ant algorithms in the literature both in the approach and in new elements introduced. For the way the solutions are built, the algorithm is called Extending Ant algorithm. The high-level procedure that governs the algorithm is quite classical (see Algorithm 1): in each generation, several feasible solutions are built; then, for the best solutions of the generation, three classical Local Search methods are applied (2-opt and forward and backward Or-exchange); and these solutions are used to update the Trail system indicating the likelihood of two customers being consecutive in the best solution. In addition, the minTrails value (used as threshold to switch to the 2nd phase of the construction procedure) and the probabilities for each route of the best solution to be copied into new solutions (at the beginning of the construction of every solution) are computed.Outgoin

Unconventional ant algorithms for vehicle routing

The algorithm developed in this work differs strongly from the other Ant algorithms in the literature both in the approach and in new elements introduced. For the way the solutions are built, the algorithm is called Extending Ant algorithm. The high-level procedure that governs the algorithm is quite classical (see Algorithm 1): in each generation, several feasible solutions are built; then, for the best solutions of the generation, three classical Local Search methods are applied (2-opt and forward and backward Or-exchange); and these solutions are used to update the Trail system indicating the likelihood of two customers being consecutive in the best solution. In addition, the minTrails value (used as threshold to switch to the 2nd phase of the construction procedure) and the probabilities for each route of the best solution to be copied into new solutions (at the beginning of the construction of every solution) are computed.Outgoin

Ant Metaheuristics with Adapted Personalities for the Vehicle Routing Problem

At each generation of an ant algorithm, each ant builds a solution step by step by adding an element to it. Each choice is based on the greedy force (short term profit or heuristic information) and the trail system (central memory which collects information during the search process). Usually, all the ants of the population have the same characteristics and behaviors. In contrast in this paper, a new type of ant metaheuristic is proposed. It relies on the use of ants with different personalities. Such a method has been adapted to the well-known vehicle routing problem, and even if it does not match the best known results, its performance is encouraging (on one benchmark instance, new best results have however been found), which opens the door to a new ant algorithm paradigm

Reliability and validity study of the Spanish adaptation of the "Wijma Delivery Expectancy/Experience Questionnaire" (W-DEQ-A).

The Wijma Delivery Expectancy/Experience Questionnaire (W-DEQ-A) is an instrument that evaluates fear of childbirth through the expectations of women in relation to childbirth and their experience during the birth. The objective of this study was to translate the W-DEQ-A into Spanish and analyse its reliability and validity. The study was carried out in two phases: (1) adapting the questionnaire to Spanish and (2) a transversal study in a sample of 273 pregnant women in the Sexual and Reproductive Health centres in the Metropolitan Northern Barcelona in Catalonia (Spain). The psychometric properties were analysed in terms of reliability and construct validity. The confirmatory factorial analysis did not confirm the unidimensionality of the original structure of the WDEQ-A, as happened with the other studies in which it has previously been validated. The result of the exploratory factorial analysis suggests four factors, or dimensions, very similar but not identical to those obtained in other analysis studies of the W-DEQ-A. The Cronbach alpha and the omega scale were also adequate for all the scales and for each of the dimensions. The results of this study confirm the findings of other studies that suggest that the W-DEQ-A is multi-dimensional. In the Spanish version of the W-DEQ-A four dimensions have been identified to explore fear of childbirth in pregnant women. The Spanish version of the WDEQ-A (WDEQ-A-Sp) is reliable and valid for the measurement of fear of childbirth in clinical practice and for use in future research