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In multi-attribute decision making the number of decision elements under consideration may be huge, especially for complex, real-world problems. Typically these elements are clustered and then the clusters organized hierarchically to reduce the number of elements to be simultaneously handled. These decomposition methodologies are intended to bring the problem within the cognitive ability of decision makers. However, such methodologies have disadvantages, and it may happen that such a priori clustering is not clear, and/or the problem has previously been addressed without any grouping action. This is the situation for the case study we address, in which a panel of experts gives opinions about the operation of 15 previously established district metered areas in a real water distribution system. Large pairwise comparison matrices may also be found when building comparisons of elements using large bodies of information. In this paper, we address a consistent compression of an AHP comparison matrix that collapses the judgments corresponding to a given number of compared elements. As a result, an a posteriori clustering of various elements becomes possible. In our case study, such a clustering offers several added benefits, including the identification of hidden or unknown criteria to cluster the considered elements of the problem.
J. Benítez; S. Carpitella; A. Certa; Amilkar E. Ilaya-Ayza; Joaquín Izquierdo. Consistent clustering of entries in large pairwise comparison matrices. Journal of Computational and Applied Mathematics 2018, 343, 98 -112.
AMA StyleJ. Benítez, S. Carpitella, A. Certa, Amilkar E. Ilaya-Ayza, Joaquín Izquierdo. Consistent clustering of entries in large pairwise comparison matrices. Journal of Computational and Applied Mathematics. 2018; 343 ():98-112.
Chicago/Turabian StyleJ. Benítez; S. Carpitella; A. Certa; Amilkar E. Ilaya-Ayza; Joaquín Izquierdo. 2018. "Consistent clustering of entries in large pairwise comparison matrices." Journal of Computational and Applied Mathematics 343, no. : 98-112.
Amilkar E. Ilaya-Ayza; Carlos Martins; Enrique Campbell; Joaquín Izquierdo. Gradual transition from intermittent to continuous water supply based on multi-criteria optimization for network sector selection. Journal of Computational and Applied Mathematics 2018, 330, 1016 -1029.
AMA StyleAmilkar E. Ilaya-Ayza, Carlos Martins, Enrique Campbell, Joaquín Izquierdo. Gradual transition from intermittent to continuous water supply based on multi-criteria optimization for network sector selection. Journal of Computational and Applied Mathematics. 2018; 330 ():1016-1029.
Chicago/Turabian StyleAmilkar E. Ilaya-Ayza; Carlos Martins; Enrique Campbell; Joaquín Izquierdo. 2018. "Gradual transition from intermittent to continuous water supply based on multi-criteria optimization for network sector selection." Journal of Computational and Applied Mathematics 330, no. : 1016-1029.
Intermittent supply is a common way of delivering water in many developing countries. Limitations on water and economic resources, in addition to poor management and population growth, limit the possibilities of delivering water 24 h a day. Intermittent water supply networks are usually designed and managed in an empirical manner, or using tools and criteria devised for continuous supply systems, and this approach can produce supply inequity. In this paper, an approach based on the hydraulic capacity concept, which uses soft computing tools of graph theory and cluster analysis, is developed to define sectors, also called district metered areas (DMAs), to produce an equitable water supply. Moreover, this approach helps determine the supply time for each sector, which depends on each sector’s hydraulic characteristics. This process also includes the opinions of water company experts, the individuals who are best acquainted with the intricacies of the network.
Amilkar E. Ilaya-Ayza; Carlos Martins; Enrique Campbell; Joaquín Izquierdo. Implementation of DMAs in Intermittent Water Supply Networks Based on Equity Criteria. Water 2017, 9, 851 .
AMA StyleAmilkar E. Ilaya-Ayza, Carlos Martins, Enrique Campbell, Joaquín Izquierdo. Implementation of DMAs in Intermittent Water Supply Networks Based on Equity Criteria. Water. 2017; 9 (11):851.
Chicago/Turabian StyleAmilkar E. Ilaya-Ayza; Carlos Martins; Enrique Campbell; Joaquín Izquierdo. 2017. "Implementation of DMAs in Intermittent Water Supply Networks Based on Equity Criteria." Water 9, no. 11: 851.
Generalmente, los sistemas con suministro intermitente son diseñados para trabajar inicialmente bajo suministro continuo. Sin embargo, por diversas causas las empresas de agua adoptan el suministro intermitente. En el presente artículo se analiza este proceso de transición, de suministro continuo a intermitente. En el primer caso de estudio se evalúa la presencia de nodos favorables y nodos desfavorables en una red con suministro intermitente; esta clasificación permite comprender la inequidad en la entrega de agua y las causas de su falta en los nodos desfavorables, situación que puede ser interpretada de modo erróneo como escasez física de agua. En el segundo caso de estudio se reconstruyen las etapas de ampliación de la red del subsistema sur de Oruro, con base en las cuales se calcula la capacidad de la red y el requerimiento de agua de la población; ambos valores son comparados para establecer la etapa desde la cual el suministro es intermitente.
Amilkar E. Ilaya-Ayza; Rafael Pérez-García; Carlos Martins; Joaquín Izquierdo; Enrique Campbell. Análisis de las causas que originan el suministro de agua intermitente, caso de estudio: zona sur de la ciudad de Oruro (Bolivia). Acta Universitaria 2017, 26, 64 -73.
AMA StyleAmilkar E. Ilaya-Ayza, Rafael Pérez-García, Carlos Martins, Joaquín Izquierdo, Enrique Campbell. Análisis de las causas que originan el suministro de agua intermitente, caso de estudio: zona sur de la ciudad de Oruro (Bolivia). Acta Universitaria. 2017; 26 ():64-73.
Chicago/Turabian StyleAmilkar E. Ilaya-Ayza; Rafael Pérez-García; Carlos Martins; Joaquín Izquierdo; Enrique Campbell. 2017. "Análisis de las causas que originan el suministro de agua intermitente, caso de estudio: zona sur de la ciudad de Oruro (Bolivia)." Acta Universitaria 26, no. : 64-73.
One of the problems for water supply systems with intermittent supply is the peak flow produced at some hours of the day, which is usually much larger than that in a system with continuous supply. The main consequence is the reduction of pressure and flow at the ends or highest points of the system network. This, in turn, generates inequity in water supply and complaints from users. To reduce the peak flow, some sectors of the system must be assigned a different supply schedule. As a result, the supply curve is modified, and the peak flow is reduced. This reorganization seeks some optimal allocation schedule and must be based on various quantitative and qualitative technical criteria. This paper hybridizes integer linear programming and multi-criteria analysis to contribute with a solution proposal to the technical management of intermittent water supply systems, which provides short-term results and requires little investment for implementation. This solution does not seek perpetuating intermittent water supply. On the contrary, this methodology can be a useful tool in gradual transition processes from intermittent to continuous supply.
Amilkar E. Ilaya-Ayza; Julio Benítez; Joaquín Izquierdo; Rafael Pérez-García. Multi-criteria optimization of supply schedules in intermittent water supply systems. Journal of Computational and Applied Mathematics 2017, 309, 695 -703.
AMA StyleAmilkar E. Ilaya-Ayza, Julio Benítez, Joaquín Izquierdo, Rafael Pérez-García. Multi-criteria optimization of supply schedules in intermittent water supply systems. Journal of Computational and Applied Mathematics. 2017; 309 ():695-703.
Chicago/Turabian StyleAmilkar E. Ilaya-Ayza; Julio Benítez; Joaquín Izquierdo; Rafael Pérez-García. 2017. "Multi-criteria optimization of supply schedules in intermittent water supply systems." Journal of Computational and Applied Mathematics 309, no. : 695-703.
Water supply systems have been facing many challenges in recent decades due to the potential effects of climate change and rapid population growth. Water systems need to expand because of demographic growth. Therefore, evaluating and increasing system capacity is crucial. Specifically, we analyze network capacity as one of the main features of a system. When the network capacity starts to decrease, there is a risk that continuous supply will become intermittent. This paper discusses how network expansion carried out throughout the network life span typically reduces network capacity, thus transforming a system originally designed to work with continuous supply into a system with intermittent supply. A method is proposed to expand the network capacity in an environment of economic scarcity through a greedy algorithm that enables the definition of a schedule for pipe modification stages, and thus efficiently expands the network capacity. This method is, at the same time, an important step in the process of changing a water system from intermittent back to continuous supply—an achievement that remains one of the main challenges related to water and health in developing countries.
Amilkar E. Ilaya-Ayza; Enrique Campbell; Rafael Pérez-García; Joaquín Izquierdo. Network Capacity Assessment and Increase in Systems with Intermittent Water Supply. Water 2016, 8, 126 .
AMA StyleAmilkar E. Ilaya-Ayza, Enrique Campbell, Rafael Pérez-García, Joaquín Izquierdo. Network Capacity Assessment and Increase in Systems with Intermittent Water Supply. Water. 2016; 8 (4):126.
Chicago/Turabian StyleAmilkar E. Ilaya-Ayza; Enrique Campbell; Rafael Pérez-García; Joaquín Izquierdo. 2016. "Network Capacity Assessment and Increase in Systems with Intermittent Water Supply." Water 8, no. 4: 126.
A novel methodology to sectorize water supply networks (WSNs) depending on a main transmission line is presented in this paper. The methodology is based on concepts derived from the social network theory and graph theory (namely, community detection and shortest path respectively); and also on a multi-objective optimization process by means of agent swarm optimization (ASO). A series of energy, operative, and economic criteria are optimized in this process. The core idea is to form sectors over the distribution network based on communities found using a community detection algorithm (Walktrap). The methodology is flexible and enables the technical staff in water utilities to make decisions at different stages. It has been tested by generating four feasible solutions over a portion of a real WSN.
Enrique Campbell; Joaquín Izquierdo; Idel Montalvo; Amilkar E. Ilaya-Ayza; Rafael Pérez-García; Mario Tavera. A flexible methodology to sectorize water supply networks based on social network theory concepts and multi-objective optimization. Journal of Hydroinformatics 2015, 18, 62 -76.
AMA StyleEnrique Campbell, Joaquín Izquierdo, Idel Montalvo, Amilkar E. Ilaya-Ayza, Rafael Pérez-García, Mario Tavera. A flexible methodology to sectorize water supply networks based on social network theory concepts and multi-objective optimization. Journal of Hydroinformatics. 2015; 18 (1):62-76.
Chicago/Turabian StyleEnrique Campbell; Joaquín Izquierdo; Idel Montalvo; Amilkar E. Ilaya-Ayza; Rafael Pérez-García; Mario Tavera. 2015. "A flexible methodology to sectorize water supply networks based on social network theory concepts and multi-objective optimization." Journal of Hydroinformatics 18, no. 1: 62-76.