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Publicações

Publicações por LIAAD

2023

Energy Flows Optimization in a Renewable Energy Community with Storage Systems Integration

Autores
Araújo, I; Cerveira, A; Baptista, J;

Publicação
Renewable Energy and Power Quality Journal

Abstract
Currently, there is increasing implementation of renewable energy communities, where consumers and producers come together to form energy cooperatives. This growing trend has been accompanied by several studies aiming to optimize energy exchanges and sharing inside the community, always taking into account the most favorable tariff regimes for community members. This paper presents an analysis that, based on applying a linear programming model, optimizes energy transactions in a renewable energy community with the integration of storage systems. The results show the developed model's effectiveness, presenting substantial profits for the community.

2023

Offshore Wind Farm Layout Optimisation Considering Wake Effect and Power Losses

Autores
Baptista, J; Jesus, B; Cerveira, A; Pires, EJS;

Publicação
SUSTAINABILITY

Abstract
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.

2023

Solving a harvest scheduling optimization problem with constraints on clearcut area and clearcut proximity

Autores
Martins, I; Alvelos, F; Cerveira, A; Kaspar, J; Marusák, R;

Publicação
INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH

Abstract
This study aims at solving a harvesting scheduling optimization problem with constraints on the clearcut area with additional constraints on clearcut proximity. The objective function is defined as the net present value generated by harvesting discounted by a penalty for each clearcut. This problem arises to reduce the negative environmental impact of excessive harvesting. We propose the connected-bucket model, the so-called bucket model with additional constraints on bucket connectivity and two definitions of stand adjacency, and a Dantzig-Wolfe decomposition. The decomposed model is solved by branch-and-price and the connected-bucket model by a general-purpose mixed integer programming solver (CPLEX). We compare the quality of the solutions obtained with both approaches for real instances. The branch-and-price approach found better solutions for the majority of the instances.

2023

Impact of Fire Recurrence and Induced Water Stress on Seed Germination and Root Mitotic Cell Cycle of Pinus pinaster Aiton

Autores
Ribeiro, S; Gaspar, MJ; Lima-Brito, J; Fonseca, T; Soares, P; Cerveira, A; Fernandes, PM; Louzada, J; Carvalho, A;

Publicação
FORESTS

Abstract
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.

2023

Self-Sustainability Assessment for a High Building Based on Linear Programming and Computational Fluid Dynamics

Autores
Oliveira, C; Baptista, J; Cerveira, A;

Publicação
ALGORITHMS

Abstract
With excess energy use from non-renewable sources, new energy generation solutions must be adopted to make up for this excess. In this sense, the integration of renewable energy sources in high-rise buildings reduces the need for energy from the national power grid to maximize the self-sustainability of common services. Moreover, self-consumption in low-voltage and medium-voltage networks strongly facilitates a reduction in external energy dependence. For consumers, the benefits of installing small wind turbines and energy storage systems include tax benefits and reduced electricity bills as well as a profitable system after the payback period. This paper focuses on assessing the wind potential in a high-rise building through computational fluid dynamics (CFD) simulations, quantifying the potential for wind energy production by small wind turbines (WT) at the installation site. Furthermore, a mathematical model is proposed to optimize wind energy production for a self-consumption system to minimize the total cost of energy purchased from the grid, maximizing the return on investment. The potential of a CFD-based project practice that has wide application in developing the most varied processes and equipment results in a huge reduction in the time and costs spent compared to conventional practices. Furthermore, the optimization model guarantees a significant decrease in the energy purchased at peak hours through the energy stored in energy storage systems (ESS). The results show that the efficiency of the proposed model leads to an investment amortization period of 7 years for a lifetime of 20 years.

2023

Confronting security and privacy challenges in digital marketing

Autores
Pires P.B.; Santos J.D.; Pereira I.V.; Torres A.I.;

Publicação
Confronting Security and Privacy Challenges in Digital Marketing

Abstract
Marketing, and specifically its digital marketing component, is being challenged by disruptive innovations, which are creating new, unique, and unusual opportunities, and with the emergence of new paradigms and models. Other areas of knowledge have embraced these innovations with swiftness, adapting promptly and using them as leverage to create new paradigms, models, and realities. Marketing, in clear opposition, has been somewhat dismissive, ignoring the potential of these new contexts that are emerging, some of which are already unavoidable. Confronting Security and Privacy Challenges in Digital Marketing identifies the most relevant issues in the current context of digital marketing and explores the implications, opportunities, and challenges of leveraging marketing strategies with digital innovations. This book explores the impact that these disruptive innovations are having on digital marketing, pointing out guidelines for organizations to leverage their strategy on the opportunities created by them. Covering topics such as blockchain technology, artificial intelligence, and virtual reality, this book is ideal for academicians, marketing professionals, researchers, and more.

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