Documents disponibles écrits par cet auteur

Breaching parameters for earth and rockfill dams / Xu, Y. in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 12 (Décembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1957–1970 Titre : Breaching parameters for earth and rockfill dams Type de document : texte imprimé Auteurs : Xu, Y., Auteur ; Zhang, L. M., Auteur Année de publication : 2010 Article en page(s) : pp. 1957–1970 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : DamsDam  failureDam  safetyErosionReservoirsRisk  management Résumé : Dam risk analysis is at the heart of dam failure prevention and mitigation. In order to assess dam risk, it is essential to conduct a quantitative analysis of the process of a dam breach, which can be described by such parameters as breach geometry, breaching duration, and peak outflow rate. The main objective of this paper is to develop robust empirical formulas with physical meaning for predicting dam breaching parameters based on past dam failure data. A database of 182 earth and rockfill dam failure cases has been compiled; among these cases nearly one-half are for large dams higher than 15 m. A multiparameter nonlinear regression model is recommended to develop empirical relationships between five breaching parameters (breach depth, breach top width, average breach width, peak outflow rate, and failure time) and five selected dam and reservoir control variables (dam height, reservoir shape coefficient, dam type, failure mode, and dam erodibility). The relative importance of each control variable is evaluated. The dam erodibility is found to be the most important factor, influencing all five breaching parameters. The reservoir shape coefficient and the failure mode also play an important role in the prediction models. Two case studies are presented to show the application of the empirical models developed in this paper. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000162 [article] Breaching parameters for earth and rockfill dams [texte imprimé] / Xu, Y., Auteur ; Zhang, L. M., Auteur . - 2010 . - pp. 1957–1970. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1957–1970 Mots-clés : DamsDam  failureDam  safetyErosionReservoirsRisk  management Résumé : Dam risk analysis is at the heart of dam failure prevention and mitigation. In order to assess dam risk, it is essential to conduct a quantitative analysis of the process of a dam breach, which can be described by such parameters as breach geometry, breaching duration, and peak outflow rate. The main objective of this paper is to develop robust empirical formulas with physical meaning for predicting dam breaching parameters based on past dam failure data. A database of 182 earth and rockfill dam failure cases has been compiled; among these cases nearly one-half are for large dams higher than 15 m. A multiparameter nonlinear regression model is recommended to develop empirical relationships between five breaching parameters (breach depth, breach top width, average breach width, peak outflow rate, and failure time) and five selected dam and reservoir control variables (dam height, reservoir shape coefficient, dam type, failure mode, and dam erodibility). The relative importance of each control variable is evaluated. The dam erodibility is found to be the most important factor, influencing all five breaching parameters. The reservoir shape coefficient and the failure mode also play an important role in the prediction models. Two case studies are presented to show the application of the empirical models developed in this paper. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000162

Solving multi-objective multicast routing problems by evolutionary multi-objective simulated annealing algorithms with variable neighbourhoods / Xu, Y. in Journal of the operational research society (JORS), Vol. 62 N° 2 Special issue (Fevrier 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 2 Special issue (Fevrier 2011) . - pp. 313–325 Titre : Solving multi-objective multicast routing problems by evolutionary multi-objective simulated annealing algorithms with variable neighbourhoods Type de document : texte imprimé Auteurs : Xu, Y., Auteur ; Qu, R., Auteur Année de publication : 2011 Article en page(s) : pp. 313–325 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Multi-objective  optimisation  Evolutionary  multi-objective  simulated  annealing  Variable  neighbourhood  search  Multicast  routing Index. décimale : 001.424 Résumé : This paper presents the investigation of an evolutionary multi-objective simulated annealing (EMOSA) algorithm with variable neighbourhoods to solve the multi-objective multicast routing problems in telecommunications. The hybrid algorithm aims to carry out a more flexible and adaptive exploration in the complex search space by using features of the variable neighbourhood search to find more non-dominated solutions in the Pareto front. Different neighbourhood strictures have been designed with regard to the set of objectives, aiming to drive the search towards optimising all objectives simultaneously. A large number of simulations have been carried out on benchmark instances and random networks with real world features including cost, delay and link utilisations. Experimental results demonstrate that the proposed EMOSA algorithm with variable neighbourhoods is able to find high-quality non-dominated solutions for the problems tested. In particular, the neighbourhood structures that are specifically designed for each objective significantly improved the performance of the proposed algorithm compared with variants of the algorithm with a single neighbourhood. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n2/abs/jors2010138a.html [article] Solving multi-objective multicast routing problems by evolutionary multi-objective simulated annealing algorithms with variable neighbourhoods [texte imprimé] / Xu, Y., Auteur ; Qu, R., Auteur . - 2011 . - pp. 313–325. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 2 Special issue (Fevrier 2011) . - pp. 313–325 Mots-clés : Multi-objective  optimisation  Evolutionary  multi-objective  simulated  annealing  Variable  neighbourhood  search  Multicast  routing Index. décimale : 001.424 Résumé : This paper presents the investigation of an evolutionary multi-objective simulated annealing (EMOSA) algorithm with variable neighbourhoods to solve the multi-objective multicast routing problems in telecommunications. The hybrid algorithm aims to carry out a more flexible and adaptive exploration in the complex search space by using features of the variable neighbourhood search to find more non-dominated solutions in the Pareto front. Different neighbourhood strictures have been designed with regard to the set of objectives, aiming to drive the search towards optimising all objectives simultaneously. A large number of simulations have been carried out on benchmark instances and random networks with real world features including cost, delay and link utilisations. Experimental results demonstrate that the proposed EMOSA algorithm with variable neighbourhoods is able to find high-quality non-dominated solutions for the problems tested. In particular, the neighbourhood structures that are specifically designed for each objective significantly improved the performance of the proposed algorithm compared with variants of the algorithm with a single neighbourhood. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n2/abs/jors2010138a.html