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- An Application of Preference-Inspired Co-Evolutionary Algorithm to SectorizationPublication . Ozturk, E. Goksu; Rocha, Pedro; Sousa, Filipe; Lima, Maria Margarida; Rodrigues, Ana Maria; Soeiro Ferreira, José; Catarina Nunes, Ana; Lopes, Isabel Cristina; Oliveira, CristinaSectorization problems have significant challenges arising from the many objectives that must be optimised simultaneously. Several methods exist to deal with these many-objective optimisation problems, but each has its limitations. This paper analyses an application of Preference Inspired Co-Evolutionary Algorithms, with goal vectors (PICEA-g) to sectorization problems. The method is tested on instances of different size difficulty levels and various configurations for mutation rate and population number. The main purpose is to find the best configuration for PICEA-g to solve sectorization problems. Performancemetrics are used to evaluate these configurations regarding the solutions’ spread, convergence, and diversity in the solution space. Several test trials showed that big and medium-sized instances perform better with low mutation rates and large population sizes. The opposite is valid for the small size instances.
- A resectorization of fire brigades in the north of PortugalPublication . Lima, Maria Margarida; Ozturk, E. Goksu; Sousa, FIlipe; Lopes, Isabel Cristina; Teles Oliveira, Cristina; Rodrigues, Ana Maria; Catarina Nunes, Ana; Soeiro Ferreira, JoséSectorization can be regarded as a division of a territory into smaller regions to deal with a complex problem involving multiple-criteria. Resectorization intends to achieve another sectorization, according to some new conditions but avoiding substantial changes. An example of this can be the distribution of geographical areas by fire brigades. In Portugal, fire brigades must protect and rescue the population in the areas surrounding their fire stations. So we will use the current sectorization, the geographic and population characteristics of the areas and the fire brigades’ response capacity to provide an optimised resectorization, in order to decrease rescue time. To achieve that, we will use a decision support system using different optimisation methods, such as Non-dominated Sorting Genetic Algorithm (NSGA II), which provides an effective sectorization concerning compactness and equilibrium criteria.
- Sectorization for managing maintenance techniciansPublication . Lopes, Isabel Cristina; Rodrigues, Ana Maria; Oliveira, Cristina; Soeiro Ferreira, José; Cortinhal, Maria Joãobetter organization of the region, or to simplify a large problem into smaller sub-problems, or to obtain groups with similar characteristics. To evaluate the quality of the solutions, three criteria are commonly used: Equilibrium (the sectors should be identical portions of the whole), Compactness (regular forms like circles are preferred, avoiding sectors shaped with ‘tentacles’), and Contiguity (avoid sectors divided into portions). Depending on the application, other criteria can also be considered, therefore multicriteria approaches should be used. Sectorization problems can arise when designing political districts, defining sales territories, managing routes for distribution of goods or collecting municipal waste, assigning neighborhoods to schools, locating health care services, police stations, or fire brigades. This talk will address the sectorization in an elevator maintenance company, where the definition of the zones assigned to each technician have an impact on the company’s efficiency and quality of service. In order to define the best sectorization, not only the maintenance plan should be considered, but also the unplanned interventions. We will discuss the different solution methods that can be applied to this case.
- Sectorization: measures and an electromagnetism based approachPublication . Rodrigues, Ana Maria; Soeiro Ferreira, JoséSectorization means dividing a set of basic units into sectors or parts, a procedure that occurs in several contexts, such as political, health and school districting, social networks and sales territory or airspace assignment, to achieve some goal or to facilitate an activity. This presentation will focus on three main issues: Measures, a new approach to sectorization problems and an application in waste collection. When designing or comparing sectors different characteristics are usually taken into account. Some are commonly used, and they are related to the concepts of contiguity, equilibrium and compactness. These fundamental characteristics will be addressed, by defining new generic measures and by proposing a new measure, desirability, connected with the idea of preference. A new approach to sectorization inspired in Coulomb’s Law, which establishes a relation of force between electrically charged points, will be proposed. A charged point represents a small region with specific characteristics/values creating relations of attraction/repulsion with the others (two by two), proportional to the charges and inversely proportional to their distance. Finally, a real case about sectorization and vehicle routing in solid waste collection will be mentioned.
- Measures in Sectorization ProblemsPublication . Rodrigues, Ana Maria; Soeiro Ferreira, JoséSectorization means dividing a whole into parts (sectors), a procedure that occurs in many contexts and applications, usually to achieve some goal or to facilitate an activity. The objective may be a better organization or simplification of a large problem into smaller sub-problems. Examples of applications are political districting and sales territory division. When designing/comparing sectors some characteristics such as contiguity, equilibrium and compactness are usually considered. This paper presents and describes new generic measures and proposes a new measure, desirability, connected with the idea of preference.
- Recolha de resíduos sólidos urbanos - otimização de rotasPublication . Rodrigues, Ana Maria; Soeiro Ferreira, JoséEste trabalho dá a conhecer um novo problema, Problema Capacitado de Rotas em Arcos Misto, com Múltiplos Aterros Limitados. Baseado na situação de recolha/transporte de Resíduos Sólidos Urbanos no concelho de Monção, são apresentadas características que, não sendo únicas em Portugal, nunca foram mencionadas na literatura. Diferencia-se pela existência de diversos pontos de deposição que, especialmente devido às reduzidas dimensões, apresentam restrições relacionadas com o número de visitas recebidas por dia. Um novo modelo de otimização, baseado na formulação do Mixed Ca- pacitated Arc Routing Problem é apresentado. São incluídos resultados computacionais provenientes de instâncias adaptadas da literatura e do problema real descrito.
- Setorização aplicada à definição de rotasPublication . Rodrigues, Ana Maria; Soeiro Ferreira, JoséA Setorização entendida como a divisão de um território em regiões mais pequenas pode apresentar vantagens em problemas de rotas com capacidades. Decidir, a priori, que região atribuir a que veículos, reduz substancialmente a dimensão das instâncias e conduz a resultados que, para além de serem obtidos de forma mais rápida podem expressar o interesse do agente decisor. A introdução de sectores em rotas de veículos permite igualmente lidar com situações de planeamento/calendário e outras restrições. Uma situação real será apresentada onde uma abordagem integrada sectores-rotas foi aplicada.
- Sectors and routes in solid waste collectionPublication . Rodrigues, Ana Maria; Soeiro Ferreira, JoséCollecting and transporting solid waste is a constant problem for municipalities and populations in general. Waste management should take into account the preservation of the environment and the reduction of costs. The goal with this paper is to address a real-life solid waste problem. The case reveals some general and specific characteristics which are not rare, but are not widely addressed in the literature. Furthermore, new methods and models to deal with sectorization and routing are introduced, which can be extended to other applications. Sectorization and routing are tackled following a two-phase approach. In the first phase, a new method is described for sectorization based on electromagnetism and Coulomb’s Law. The second phase addresses the routing problems in each sector. The paper addresses not only territorial division, but also the frequency with which waste is collected, which is a critical issue in these types of applications. Special characteristics related to the number and type of deposition points were also a motivation for this work. A new model for a Mixed Capacitated Arc Routing Problem with Limited Multi-Landfills is proposed and tested in real instances. The computational results achieved confirm the effectiveness of the entire approach.
- Cutting path as a rural postman problemPublication . Rodrigues, Ana Maria; Soeiro Ferreira, JoséThe Rural Postman Problem (RPP) is a particular Arc Routing Problem (ARP) which consists of determining a minimum cost circuit on a graph so that a given subset of required edges is traversed. The RPP is an NP-hard problem with significant real-life applications. This paper introduces an original approach based on Memetic Algorithms - the MARP algorithm - to solve the RPP and, also deals with an interesting Industrial Application, which focuses on the path optimization for component cutting operations. Memetic Algorithms are a class of Metaheuristics which may be seen as a population strategy that involves cooperation and competition processes between population elements and integrates “social knowledge”, using a local search procedure. The MARP algorithm is tested with different groups of instances and the results are compared with those gathered from other publications. MARP is also used in the context of various real-life applications.
- Creating homogeneous sectors: criteria and applications of sectorizationPublication . Lopes, Isabel Cristina; Lima, Maria Margarida; Ozturk, E. Goksu; Rodrigues, Ana Maria; Nunes, Ana Catarina; Oliveira, Cristina; Soeiro Ferreira, José; Rocha, PedroSectorization is the process of grouping a set of previously defined basic units (points or small areas) into a fixed number of sectors. Sectorization is also known in the literature as districting or territory design, and is usually performed to optimize one or more criteria regarding the geographic characteristics of the territory and the planning purposes of sectors. The most common criteria are equilibrium, compactness and contiguity, which can be measured in many ways. Sectorization is similar to clustering but with a different motivation. Both aggregate smaller units into groups. But, while clustering strives for inner similarity of data, sectorization aims at outer homogeneity [1]. In clustering, groups should be very different from each other, and similar points are classified in the same cluster. In sectorization, groups should be very similar to each other, and therefore very different points can be grouped in the same sector. We classify sectorization problems into four types: basic sectorization, sectorization with service centers, resectorization, and dynamic sectorization. A Decision Support System for Sectorization, D3S, is being developed to deal with these four types of problems. Multi-objective genetic algorithms were implemented in D3S using Python, and a user-friendly web interface was developed using Django. Several applications can be solved with D3S, such as political districting, sales territory design, delivery service zones, and assignment of fire stations and health services to the population.