Prioritizing Water Distribution and Sewer Network Maintenance Activities

Asset management in water supply and sewerage infrastructures seeks correct planning and prioritization of the maintenance activities on their network elements. To determine the replacement priority for each network asset, an original priority model is utilized. It is based on a risk index that integrates both the probability and consequences of failure. Besides, when designing and performing work programs, water companies generally abide by the street’s topography and other urban elements, such as complete streets or street sections. This work considers street sections between the two nearest intersections as the operational unit

Modelo de optimización para la operativa de almacenamiento y apilado de contenedores en una terminal de contenedores portuaria

En el presente Trabajo Fin de Grado se desarrolla un modelo de optimización matemático para la operativa de almacenamiento y apilado de contenedores en una terminal de contenedores portuaria. Este modelo proporciona la posición exacta de almacenamiento que debe ocupar cada contenedor que llega a la terminal, y las relocalizaciones que dicha ubicación causa, con el fin de mantener un orden en las pilas. El objetivo del mismo es minimizar los costes de traslado de los contenedores en el patio junto con el número de relocalizaciones generadas. Para la resolución del modelo se ha utilizado el software de optimización GUROBI, el cual se ha implementado a través de diversos archivos en lenguaje AMPL. Para realizar el análisis de los resultados obtenidos se ha recurrido al programa Microsoft Excel, simulando diversos escenarios para así comprobar el funcionamiento y la eficiencia del modelo.This final degree project presents a mathematical optimization model that optimizes the stocking and transporting of containers decisions in a port containers terminal. The model provides the exact position for stocking each container and the corresponding relocations that the new stocking position could lead. The objective of the model is to minimize the costs of shifting the containers in the yard along with the number of reallocations generated. The model is implemented and solved using GUROBI software that requires the handling of several AMPL files to deal with the data and variables of the problem. The results are analysed using Microsoft Excel software, which undertakes and simulates several hypothetical situations to perform the efficiency of the model.Universidad de Sevilla. Grado en Ingeniería de Tecnologías Industriale

Diseño óptimo de redes de distribución de agua mediante algoritmos de búsqueda tabú

En este Trabajo Fin de Máster se desarrolla un método de optimización que permite resolver el problema de diseño y planificación de redes hidráulicas de distribución. Las redes de abastecimiento son infraestructuras de gran importancia que suponen grandes inversiones. Con el crecimiento demográfico de las ciudades, y el aumento de la contaminación, están apareciendo nuevos retos de diseño y gestión de las mismas. Debido a las características intrínsecas de los sistemas hidráulicos y a la naturaleza discreta de algunas de sus variables, éste es un problema no-lineal mixto y entero. Ante este tipo de problemas de alta complejidad han surgido técnicas de resolución, como las metaheurísticas, que permiten obtener resultados satisfactorios en tiempos reducidos. En este trabajo se diseña un algoritmo de búsqueda tabú ajustando los parámetros a la problemática de estudio. Para la validación del algoritmo se ha resuelto el problema de diseño de redes de distribución aplicado a la red de Alperovits. Esta red ha sido utilizada por muchos autores en la literatura, permitiendo la comparación de los resultados obtenidos en este trabajo con aquellos que obtuvieron otros autores aplicando otras técnicas de resolución. La ejecución del algoritmo se realiza usando el lenguaje de programación Python y, en concreto, una de sus librerías, WNTR, que permite la generación y simulación de redes hidráulicas.This Final Master Project proposes an optimization method as a tool to the design of water distribution network. Water distribution networks are very important infrastructures that involve huge investments. Due to the population growth of cities and the increase of pollution, new challenges are emerging in the design and manage of those networks. The intrinsic characteristics of hydraulic systems and the discrete nature of some of its variables make this a nonlinear mixed integer problem. There are different techniques to face this kind of complex problems like the meta-heuristics which enables satisfactory solutions in a short period of time. In this work, a Tabu Search algorithm, meta-heuristic that simulates the human mind behaviour, is developed. The parameters are carefully selected for the subject of study. In order to validate the method the design of water distribution network problem have been applied to a specific case, the Alperovits network. Many authors used this network in the past so it enables to compare the results obtained in this work and analyze its efficiency. The algorithm is implemented in Pyhton, a powerful programing language. It contains many libraries which execute different calculation. WNTR is one of the libraries used in the code that allows simulating hydraulic networks.Universidad de Sevilla. Máster Universitario en Organización Industrial y Gestión de Empresa

An evolutionary fuzzy system to support the replacement policy in water supply networks: The ranking of pipes according to their failure risk

Article number 107731In this study, an evolutionary fuzzy system is proposed to predict unexpected pipe failures in water supply networks. The system seeks to underpin the decisions of management companies regarding the maintenance and replacement plans of pipes. On the one hand, fuzzy logic provides high degrees of interpretability over other black box models, which is requested in engineering application where decisions have social consequences. On the other hand, the genetic algorithm helps to optimize the parameters that govern the model, specifically, for two purposes: (i) the selection of variables; and (ii) the optimization of membership functions. Data from a real water supply network are used to evaluate the accuracy of the developed system. Several graphs that depict the ranking of pipes according to their risk of failure against the network length to be replaced support the choice of the most successful model. In fact, results demonstrate that the annual replacement of 6.75% of the network length makes it possible to prevent 41.14% of unexpected pipe failuresEm

Artificial neural networks to forecast failures in water supply pipes

Article number 8226The water supply networks of many countries are experiencing a drastic increase in the number of pipe failures. To reverse this tendency, it is essential to optimise the replacement plans of pipes. For this reason, companies demand pioneering techniques to predict which pipes are more prone to fail. In this study, an Artificial Neural Network (ANN) is designed to classify pipes according to their predisposition to fail based on physical and operational input variables. In addition, the usefulness and effectiveness of two sampling methods, under-sampling and over-sampling, are analysed. The implementation of the model is done using the open-source software Weka, which is specialised in machine-learning algorithms. The system is tested with a database from a real water network in Spain, obtaining high-accurate results. It is verified that the balance of the training set is imperative to increase the predictions’ accurateness. Furthermore, under-sampling prioritises true positive rates, whereas over-sampling makes the system learn to predict failures and non-failures with the same precision.Universidad de Sevilla VI-PPIT-U

Sustainable Development and Efficiency Analysis of the Major Urban Water Utilities in Spain

In Spain, the water supply service is a municipal responsibility and in general is a sector without competitors. For this reason, an efficiency analysis attains greater significance. This study uses Data Envelopment Analysis (DEA) to estimate the efficiency of different urban water utilities. An extensive data search, where several variables such as the capital expenditure, the cost of material, or the labor have been recorded, has allowed evaluating the relative efficiency of the most important Spanish water distribution networks in using their resources. Furthermore, their sustainable efficiency has also been evaluated by including a variable representing the percentage of water losses. Results reveal the weaknesses of inefficient utilities and help to detect potential aspects that these companies should improve. For instance, there is an evident incorrect management of the costs of material by many urban water utilities, which does not happen with the labor. Additionally, the most efficient water utilities regarding the sustainable efficiency help to discover target percentages of water losses for the inefficient ones.Consejería de Economía, Conocimiento, Empresas y Universidad - Junta de Andalucía - European Regional Development Fund (ERDF) PYC20- RE082 US

Machine Learning-Based Analysis of a Wind Turbine Manufacturing Operation: A Case Study

This study analyzes the lead time of the bending operation in the wind turbine tower manufacturing process. Since the operation involves a significant amount of employee interaction and the parts processed are heavy and voluminous, there is considerable variability in the recorded lead times. Therefore, a machine learning regression analysis has been applied to the bending process. Two machine learning algorithms have been used: a multivariate Linear Regression and the M5P method. The goal of the analysis is to gain a better understanding of the effect of several factors (technical, organizational, and experience-related) on the bending process times, and to attempt to predict these operation times as a way to increase the planning and controlling capacity of the plant. The inclusion of the experience-related variables serves as a basis for analyzing the impact of age and experience on the time-wise efficiency of workers. The proposed approach has been applied to the case of a Spanish wind turbine tower manufacturer, using data from the operation of its plant gathered between 2018 and 2021. The results show that the trained models have a moderate predictive power. Additionally, as shown by the output of the regression analysis, there are variables that would presumably have a significant impact on lead times that have been found to be non-factors, as well as some variables that generate an unexpected degree of variability

Aplicación de la regresión logística para la predicción de roturas de tuberías en redes de abastecimiento de agua

Las roturas de tuberías en redes de abastecimiento de agua provocan serios problemas para las compañías encargadas de su gestión. Con objeto de reducir el número de roturas inesperadas, se propone un método predictivo de clasificación de las tuberías que utiliza la regresión logística, junto con técnicas avanzadas de procesamiento de datos, como el equilibrado de clases o la validación cruzada. La metodología se ha aplicado al caso real de la red de abastecimiento de Sevilla. Los resultados muestran que podría llegar a predecirse el 85.9% de las roturas de tuberías, siendo 76.6% la precisión total del modelo.Universidad de Sevilla (España) VI PPIT-U

Modelos lineales mixtos para la programación de la producción con una sola etapa: estado del arte

En este documento se presenta una revisión bibliográfica y una posterior taxonomía para modelos de programación lineal entera mixta (PLEM) en planificación de la producción. En concreto, se analizan modelos de una sola etapa por su interés en diversos tipos de procesos productivos. Se han estudiado un total de 30 modelos que se clasifican en cuanto a los objetivos perseguidos, a su formulación, a su representación y, además, según qué características y restricciones han sido tenidas en cuenta. Como resultado, estos modelos se presentan de forma clara y concisa dando un marco de trabajo para futuros desarrollos

Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI