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The last two decades have witnessed a new paradigm in terms of electrical energy production. The production of electricity from renewable sources has come to play a leading role, thus allowing us not only to face the global increase in energy consumption, but also to achieve the objectives of decarbonising the economies of several countries. In this scenario, where onshore wind energy is practically exhausted, several countries are betting on constructing offshore wind farms. Since all the costs involved are higher when compared to onshore, optimising the efficiency of this type of infrastructure as much as possible is essential. The main aim of this paper was to develop an optimisation model to find the best wind turbine locations for offshore wind farms and to obtain the wind farm layout to maximise the profit, avoiding cable crossings, taking into account the wake effect and power losses. The ideal positioning of wind turbines is important for maximising the production of electrical energy. Furthermore, a techno-economic analysis was performed to calculate the main economic indicators, namely the net present value, the internal rate of return, and the payback period, to support the decision-making. The results showed that the developed model found the best solution that maximised the profits of the wind farm during its lifetime. It also showed that the location of the offshore substation played a key role in achieving these goals.

Climate change will increase the frequency of drought, heat waves, and wildfires. We intended to analyse how fire recurrence and/or induced water stress can affect seed germination and root cell division in Pinus pinaster Aiton. Seeds from stands with no prior fire history and from post-fire regeneration (in areas burnt once, twice, and thrice) in northern Portugal were germinated in distilled water (control) and polyethylene glycol (PEG) to simulate water stress for four weeks, followed by a recovery period. Roots were analysed cytogenetically. The germination index of the Pinus pinaster seeds was not statistically influenced by the induction of osmotic stress, nor by the fire recurrence of the stands. The mean germination time (MGT) was 10–29 days and 1–36 days for the stress and recovery periods, respectively, and increased with PEG concentration. The 20% PEG treatment inhibited root growth after germination. The 10% PEG treatment induced a high frequency of cytogenetic anomalies, mostly in the sites which experienced fire exposure. While fire recurrence did not affect the germination rate, it seemed to reduce the water stress response, negatively impacting cell division and impair root growth.

Vineyard replacement is a common practice in every wine-growing farm since the grapevine production decays over time and requires a new vine to ensure the business sustainability. In this paper, we formulate a simple discrete model that captures the vineyard's main dynamics such as production values and grape quality. Then, by applying binary non-linear programming methods to find the vineyard replacement trigger, we seek the optimal solution concerning different governmental subsidies to the target producer., This is a preprint of a paper whose final and definite form is with 'Discontinuity, Nonlinearity and Complexity', available from [https://lhscientificpublishing.com/Journals/DNC-Default.aspx]. Submitted 30 May 2018; Revised 28 July 2018; Accepted 6 Sept 2018

The success of forest management towards achieving desired outcomes depends on various factors and can be improved through forest planning based on optimization approaches. Regardless of the owner type (state, private or common land) and/or governance model, the number of owners or management bodies considered in most studies is low, typically involving one owner/management body or a very small group. This study extends the approach of formulating a Forest Management Plan (FMP) to a large forest area, consisting of areas with different management bodies. The FMP model returns the harvest schedule that maximizes the volume of wood harvested during the planning horizon, while ensuring (1) sustainability and environmental constraints at the overall scale and (2) independent revenues for each management body. The FMP is tested in a real forested area, consisting of 22 common lands, governed by local communities for a planning period of 30 years. The results show that our approach is appropriate for several management bodies. When evaluating the impact of grouping areas (and their owner bodies) on the total volume removed, a comparison of the FMP model with an alternative model that allows for independent management (FMP-IND) showed significant differences, in terms of total volume removed at the end of the horizon. Global management leads to a reduction of about 8.6% in the total removed volume; however, it will ensure a heritage of well-diversified stands, in terms of age classes. The results highlight the importance of managing multi-stakeholder forest areas as a whole, instead of being managed independently, if the aim is to assure more sustainable management of forest resources in the mid and long term.

Forests assume a great socioeconomic and environmental importance, requiring good management decisions to value and care for these natural resources. In Portugal, forest land use accounts for 34.5% of the continental area. The softwood species with the highest representation is maritime pine (Pinus pinaster Ait.). Traditionally, the species is managed as pure and even-aged stands for timber production, with a rotation age of 45 to 50 years. Depending on the initial stand density, the stands are thinned 2 to 4 times during the rotation period. Disturbances associated with forest fires have a negative impact on the age structure of stands over time, as they result in a narrow range of stand ages. This age homogenization over large forest areas increases with the recurrence and size of forest fires, bringing new challenges to forest management, namely the difficulty in ensuring the long-term sustainability of the wood supply. The problem aggravates with the increasing demand pressure on pine wood. This article aims to suggest a framework of DSS for Pinus pinaster that can effectively support the management of forest areas under these circumstances, i.e., narrow age ranges and high demand of harvested timber volume. A communal woodland area in the Northern region of Portugal affected by forest fires was selected as a study case. The Modispinaster model was used as the basis of the DSS, to simulate growth scenarios and interventions along the optional rotation period. Two clear-cut ages were considered: 25 and 40 years. The results obtained were the input data for an integer linear programming (ILP) model to obtain the plan that maximizes the volume of timber harvested in the study area, during the planning horizon. The ILP model has constraints bounding the area of clearings, and sustainability, operational and forestry restrictions. The computational results are a powerful tool for guidance in the decision-making of scheduling and forecasting the execution of interventions determining the set of stands that are exploited according to the different scenarios and the period in which the clear-cut is made throughout the planning horizon. Considering all constraints, the solution allows a balanced extraction of a total of 685 m3·ha−1, over the 50-year horizon, as well as the representation of all age classes at the end of the planning period.

Teaching project management and industrial optimization to engineering students requires real-world experiences in which they can explicitly integrate, apply and develop work-ready skills, such as critical thinking, communication, and teamwork. This paper presents an exploratory case study research describing an online Project-based Learning (PjBL) experience aimed at tackling the challenge of decreasing the ecological footprint in the university campus generated by the local locomotion of students from university-home and/or home-university. The experience was implemented from February to June 2020, in the middle of the COVID-19 pandemic, with 9 participating students enrolled in the ‘Industrial Management I’ course, part of the Master of Science in Mechanical Engineering at the University of Tras-os-Montcs and Alto Douro (UTAD), Portugal. We firstly describe the course in terms of the key driving question, the learning goals, the educational activities, the collaboration among students, the scaffolding technologies, and the tangible artefacts produced. We further discuss the preliminary results of the study by taking into account the main tangible learning artefact produced by the students - a carpooling model proposal for the UTAD student community - as well as the data collected from a post, self-completion questionnaire on students' perceptions about the PjBL experience. Finally, we outline implications for the teaching practice and some concerns that need to be addressed in future course editions.

Green energy has become a media issue due to climate changes, and consequently, the population has become more aware of pollution. Wind farms are an essential energy production alternative to fossil energy. The incentive to produce wind energy was a government policy some decades ago to decrease carbon emissions. In recent decades, wind farms were formed by a substation and a couple of turbines. Nowadays, wind farms are designed with hundreds of turbines requiring more than one substation. This paper formulates an integer linear programming model to design wind farms’ cable layout with several turbines. The proposed model obtains the optimal solution considering different cable types, infrastructure costs, and energy losses. An additional constraint was considered to limit the number of cables that cross a walkway, i.e., the number of connections between a set of wind turbines and the remaining wind farm. Furthermore, considering a discrete set of possible turbine locations, the model allows identifying those that should be present in the optimal solution, thereby addressing the optimal location of the substation(s) in the wind farm. The paper illustrates solutions and the associated costs of two wind farms, with up to 102 turbines and three substations in the optimal solution, selected among sixteen possible places. The optimal solutions are obtained in a short time.

Resumo: Em Portugal, a disponibilidade de mão de obra tem-se revelado um fator-chave para a viticultura de montanha. Estatísticas mais recentes denotam valores preocupantes que poderão colocar em causa a produção de vinho de qualidade e o atraente conjunto de paisagens vitivinícolas consideradas um recurso potencial para o desenvolvimento do turismo. Por a região duriense ser uma das principais regiões vitivinícolas portuguesas, caracterizada por proeminente e acentuada viticultura de montanha, pretende-se, neste trabalho, simular o comportamento das suas explorações perante alterações do preço de mão de obra, recorrendo-se a modelos baseados em agentes (ABM). Foi ainda usado o software MATLAB para obter funções periódicas ajustadas aos dados caracterizadores das variáveis consideradas pertinentes, obtidas de inquéritos presenciais a 110 explorações e atendendo aos dados disponibilizados pela Rede de Informação de Contabilidades Agrícolas (RICA). Posteriormente, o software ABM (NETLOGO) foi selecionado para simular os próximos 100 anos, familiarizando a dinâmica real baseada nos dados anteriormente considerados. Dependendo do preço da mão de obra, no final do horizonte de simulação, com o preço da uva a 0,77€ /kg, das 300 explorações existentes inicialmente, sobrevivem entre 127 e 231 (42,3% a 77%). Num cenário mais otimista, com o preço da uva a 1,17 €/kg, a taxa de sobrevivência oscila entre 72,1% e 93,2%. Abstract: In Portugal, labour availability has been revealed as a key factor for the activity, particularly in mountain viticulture. The latest statistics present worrying values that could undermine the production of quality wine and the attractive set of wine landscapes considered as a potential resource for tourism development. The Douro Region is one of the main Portuguese wine regions, characterized by a prominent and accentuated mountain viticulture. This paper aims to simulate the behaviour of its farms about the changes in the price of labour, through Agent-Based Models (ABM). The MATLAB software was used to obtain periodic functions adjusted to the data that characterize the relevant variables, obtained from face-to-face surveys of 110 farms, and taking into account the data provided by PTFADN. Subsequently, the ABM software (NETLOGO) was selected to simulate the next 100 years, familiarizing the real dynamics based on the previously considered data. Depending on the price of labour at the end of the simulation horizon, with a grape price of 0,77 €/kg, from the 300 initially existing farms survive between 127 and 231 (42,3 - 77%). In a more optimistic scenario, with a grape price of 1,17 €/kg, the survival rate ranges between 72.1 and 93.2%.

Review The main objective of the present work was to review the current knowledge about the factors that influence the different phases of the natural regeneration of maritime pine (Pinus pinaster Aiton) and propose scientifically based management schedules. The review focused on the natural regeneration of maritime pine within its most representative areas (Portugal, Spain, and France). First, a brief characterisation of the main phases of the natural regeneration of maritime pine is described. Next, information on the factors affecting the natural regeneration of the species is provided, highlighting its positive and negative effects. Finally, management proposals are presented to promote the natural regeneration of maritime pine species. Numerous factors influencing the natural regeneration of maritime pine were identified. Fires and climatic factors can intervene in all three regeneration phases (seeding, germination, and seedling survival and development). The natural regeneration failure of maritime pine species can be aggravated in drier scenarios. Forest management plays an important role as it can promote the natural regeneration of the species info:eu-repo/semantics/publishedVersion

The wine industry has a high business volume and adds value to the economy. This chapter intends to predict the wine firm performance of three of the most relevant Portuguese regions, by resorting to data available on the Portuguese Farm Accountancy Data Network (PTFADN, Resultados medios por exploracao. Available on http://www.gpp.pt/index.php/rica/rede-de-informacao-de-contabilidades-agricolas-rica. Accessed 13 Mar 2018, 2001–2015). The existing social, economic and environmental parameters allowed us to perform function fitting with MATLAB, in order to attain information about the variable’s behaviour. Through the Agent-Based Model (ABM) simulations, it is possible to realize that, in general, the Alentejo region is substantially well prepared to deal with negative scenarios when compared with North and Central regions. Alternative scenarios can be performed in order to develop overall governmental policy recommendations, so as to ensure the sustainability of the three regions.

The use of industrial by-products to produce new types of cement-substitute binders is gaining significant momentum, especially through the alkaline activation technique. However, the exact curing conditions that should be considered with each binder variation have not yet been fully understood. The aim of the present work is thus the statistical analysis of the effects of several factors, namely filler/precursor ratio and curing humidity, on the compressive strength of different mixtures prepared with mine tailings (filler), fly ash (precursor) and an alkali activator based on sodium hydroxide. Five different types of mixture were prepared, with filler/precursor ratios of 80/20, 60/40, 40/60, 20/80 and 0/100. All the specimens were cured at 80oC for 7 days, after which they were submitted to a uniaxial compression strength (UCS) test. Three different values of curing humidity were considered, namely 25%, 50% and 75%. Each UCS value was the average of 9 different specimens tested. The aim of the present research is to establish how much these two factors (inert/precursor ratio and curing humidity) influence the UCS. For that purpose, a two-way Analysis of Variance (ANOVA), with interaction, was performed; followed by a Tuckey's Post hoc test. The results showed statistically significant differences for at least one humidity value F(2,127) = 31.647 (p

Understanding the role of the climate on the wine production is one of the major concerns of this sector since the environment usually determines the output of this industry. There are only a few previous studies that attempted to compile these environmental effects as an index, usually considering the temperature and the precipitation as their core variables. The present study suggests a new climate index which is based on descriptive statistics. Our index tries to mimic the target region characteristics and avoid the past studies premise of imposing previously conceived restrictions such as a fixed optimal climate. We then used yearly production and daily temperature data (1950-2016) from the Portuguese Minho wine region to test our proposed index and compare it with Ribéreau-Gayon and Peynaud (RGP, Ribéreau-Gayon et al., 2003) and Growing Degree-Days (GDD, Winkler et al., 1974) indexes. Our results showed that the newly proposed index may outperform the explanatory power of the other indexes and, in addition, may output interesting and unknown characteristics such as the different ideal temperatures regarding the studied region.

Research Highlights: This study bridges a gap of knowledge about the maximum size&ndash, density trajectory for juvenile stands of maritime pine. The continuity of the trajectory along the development stages to maturity is assured with a straightforward approach providing support to determine optimum density along all the revolution periods for the species. Background and Objectives: Forest fire is a significant threat to forests in the Mediterranean regions, but also a natural disturbance that plays a vital role in the perpetuation of forest stands. In recent decades, there has been an increase of burnt area in maritime forests in Portugal, followed by an increased interest in managing the natural and usually abundant regeneration occurring after the fires. The gap in the knowledge of growth dynamics for juvenile stages, for these forest systems, currently constrains their correct management, for forest planning, particularly in determining the optimal densities. The study aims to identify the maximum attainable density trajectory at the early stages of development of the species that could support a non-empirical definition of silvicultural prescriptions and thinning decisions, along the revolution. Materials and Methods: A representative data set collected in stands regenerated after fire supports the analysis of the maximum size&ndash, density trajectory for the species. Results: The maximum size&ndash, density trajectory for the juvenile stands deviates from the expected trajectory defined in the self-thinning line published for the species. Significant deviation occurs at the lower end of the line, indicating the need for a reevaluation of the existing self-thinning line. We propose a new self-thinning model for the species that explicitly considers the behavior of size&ndash, density for juvenile stands. The new model assures a logical continuity for the trajectory from the young stages of development to maturity. Conclusions: The proposed model based on the maximum attainable size&ndash, density trajectory provides ecological-based support to define silvicultural guidelines for management of the species.

Wind power is the source of electrical energy that has grown more over the last years, with annual rate in installed capacity around 20%. Therefore, it is important to optimize the production efficiency of wind farms. In a wind farm, the electrical energy is collected at a central substation from different wind turbines placed nearby. This paper addresses the optimal design of the cable network interconnecting the turbines to the substation aiming to minimize not only the infrastructure cost but also the cost of the energy losses in the cables. Although this problem is nonlinear, different integer linear programming models are proposed considering the wind farm technical constraints. The models are applied to three real cases Portuguese wind farms. The computational results show that the proposed models are able to compute the optimal solutions for all cases.

In the past few decades, ecological and environmental issues have dominated the forest industry worldwide, but economic aspects have been much less studied in this dynamic period. However, a sustainable and efficient forest biomass supply is critical for socio-economic development in many regions, particularly in rural areas. Nature protection efforts have contributed to reduced harvesting quotas, which have resulted in an imbalance of the environmental functions of the forests and forest management, particularly wood supply. Considering the size and distribution of forest production management units and the forest stands that compose those units, there is a clear need for improved decision-making tools that help forest managers in planning harvest sequences. The optimization of harvest scheduling should consider economic and spatial factors, which may reduce production costs by increasing the logistic efficiency. Moreover, incorporating maximum harvesting opening size constraints into planning can help preserve biodiversity. This article presents a new spatial harvest scheduling model based on the integer programming method; it was developed using real data from a forest production unit located in the northern part of the southeast region of Brazil. The goal of the proposed scheduling approach is to maximize the net present value and concentrate the harvesting locations in each period. In spite of the fact that the object of the study is plantation forest under management different to common conditions in Europe or North America, the model is flexible and can be used in management of forest in Central Europe.

This study aims to develop an approach for the management of a forest of maritime pine located in the north region of Portugal. The forest is classified into five public lands, the so‐called baldios, extending over 4432 ha. These baldios are co‐managed by the Official Forest Services and the local communities mainly for timber production purposes. The forest planning involves non‐spatial and spatial constraints. Spatial constraints dictate a maximum clearcut area and an exclusion time. An integer programming model is presented and the computational results are discussed.

We consider the Weight‐constrained Minimum Spanning Tree problem (WMST). The WMST aims at finding a minimum spanning tree such that the overall tree weight does not exceed a specified limit on a graph with costs and weights associated with each edge. We present and compare, from the computational point of view, several formulations for the WMST. From preliminary computational results we propose a model that combines a formulation similar to the well known Miller‐Tucker‐Zemlin formulation with the cut‐set inequalities.

One of the classical problems in the structural optimization field is the Truss Topology Design Problem (TTDP) which deals with the selection of optimal configuration for structural systems for applications in mechanical, civil, aerospace engineering, among others. In this paper we consider a TTDP where the goal is to find the stiffest truss, under a given load and with a bound on the total volume. The design variables are the cross-section areas of the truss bars that must be chosen from a given finite set. This results in a large-scale non-convex problem with discrete variables. This problem can be formulated as a Semidefinite Programming Problem (SDP problem) with binary variables. We propose a branch and bound algorithm to solve this problem. In this paper it is considered a binary formulation of the problem, to take advantage of its structure, which admits a Knapsack problem as subproblem. Thus, trying to improve the performance of the Branch and Bound, at each step, some valid inequalities for the Knapsack problem are included.

The design of truss structures is an important engineering activity which has traditionally been done without optimization support. Nowadays we witness an increasing concern for efficiency and therefore engineers seek aid on Mathematical Programming to optimize a design. In this article, we consider a mathematical model where we maximize the stiffness with a volume constraint and bounds in the cross sectional area of the bars, [2]. The basic model is a large-scale non-convex constrained optimization problem but two equivalent problems are considered. One of them is a minimization of a convex non-smooth function in several variables (much less than in the basic model), being only one non-negative. The other is a semidefinite programming problem. We solve some instances using both alternatives and we present and compare the results.

We consider a real production planning problem occurring in a glass container manufacturing company. The goal is to minimise the average stock level during a planning horizon of one year, maintaining customers satisfaction and keeping the production at its maximum rate. Besides the production capacity, the main constraints considered are related to the number of setup changes in machines, which is restricted in each factory. The main goal is to find the best balance between the number of setups and the average stock level. We propose a decomposition of the problem into two interrelated problems: a lot-sizing problem and a scheduling problem. For each problem we propose a mathematical model that can be solved using a commercial solver package. To be an efficient managerial tool, the method should provide quickly good solutions. Therefore we solve the lot-sizing problem through a relax-and-fix heuristic and discuss the results.

Neste trabalho conjuga-se a exploração sustentável de material lenhoso com a avaliação da capacidade de propagação de fogo em pinheiro bravo num conjunto de 5 áreas comunitárias (baldios), no Norte de Portugal, para o período de 2012 a 2016. Foram considerados dois cenários: ausência de intervenção versus implementação de um plano de exploração. Para obter o plano usou-se um modelo de otimização visando a maximização do material lenhoso removido, considerando um conjunto de restrições. As caraterísticas do fogo foram determinadas com recurso ao simulador PiroPinus. Para cada parcela, registou-se a capacidade de propagação do fogo ao nível de vegetação de sub-bosque (fogo de superfície) e a propagação do fogo às copas, distinguindo-se neste caso, fogo de copas passivo ou ativo, dependendo da velocidade da propagação do fogo. Em 2012 havendo deflagração, cerca de 1/3 da área é propensa a fogo de copas. Em 2016 verificou-se uma redução nessa proporção, quer se adote ou não o plano de exploração. Isto deve-se ao estado de desenvolvimento dos povoamentos (maturidade) e à sua evolução natural, cujo crescimento se traduz num aumento da altura média a que se encontram as copas com uma concomitante redução na possibilidade de propagação do estrato superficial às copas. This study combines a sustainable forest management for timber production with the assessment of the spread of fire, in a maritime pine forest located in the northern region of Portugal, during the period 2012-2016. The study area refers to 1393 ha, distributed among five common lands called baldio areas. Two scenarios were analyzed: absence of intervention versus thinning and clear-cutting scheduling using a timber management plan. The plan was obtained by an optimization model where the goal is to maximize the removed timber given a set of constraints. The characteristics of the fire were determined with the simulator PiroPinus. The output individualizes between surface fire and crown fire, distinguishing in the case of the canopy layer, a passive or active crown fire, depending on the speed of spread of fire. In 2012 the proportion of area prone to crown fire is around 1/3. In 2016 that proportion decreases. This is due to the stand development stage of the studied stands (maturity) and to the natural evolution of the forest. The crown height increases with stand age with a simultaneous reduction in the possibility of fire spreading to the canopy layer. Cette étude combine une gestion durable des forêts pour la production de bois à l’évaluation de la propagation du feu, dans une forêt de pin maritime situé dans la région nord du Portugal, au cours de la période 2012-2016. La zone d’étude se réfère à 1393 ha, répartis entre cinq terres communes appelées zones Baldio. Deux scénarios ont été analysés: l’absence d’intervention contre l’éclaircie et coupe rase utilisant un plan de gestion forestière. Le plan a été obtenu par un modèle d’optimisation dont le but est de maximiser le bois prélevé étant donné un ensemble de contraintes. Les caractéristiques du feu ont été déterminées avec le simulateur PiroPinus. La sortie individualise le feu de surface des feux de canopée, en distinguant dans le cas de la canopée, un feu passif ou actif, en fonction de la vitesse de propagation du feu. En 2012, la proportion de la zone sujette aux feux de canopée est de 1/3 environ. En 2016, cette proportion diminue. Cela est dû à la phase de développement des peuplements étudiés (maturité) et à l’évolution naturelle de la forêt. La hauteur de la couronne augmente avec l’âge du peuplement avec une réduction simultanée de la possibilité de propagation du feu à la canopée.