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Experimental assessment of condition monitoring techniques for an OWC electrical generator operating at overload
Get PDFPublisher Copyright: © 2025Traditionally, the nominal power of a generator in renewable energy converters is determined based on its maximum mechanical input power within the drive train. Implementing this procedure for Wave Energy Converters would result in a generator operating well below its nominal power, leading to prolonged periods of suboptimal efficiency depending on the location of the device. Generators are generally engineered to manage brief periods of overload. Consequently, opting for a smaller generator and permitting it to function above its nominal power can be a viable strategy. However, it is essential to carefully evaluate the limits and operational durations specific to each application. Enhancing the operational speed may result in increased vibrations, while boosting the torque can elevate the temperature of the stator winding. This temperature rise can eventually compromise the insulation of the stator winding, leading to potential failure. At the present work, an overload operational regime of a generator, under the special operation mode of the MARMOK-Idom Oscillating Water Column (OWC) Wave Energy Converter (WEC), will be evaluated at overload till the end of its life. The testing procedure uses an “accelerated testing” concept, introducing consecutive representative power peaks instead of real wave trains, reflecting the probable mechanical power peak magnitudes and durations to simulate real conditions. Several generator condition monitoring alternatives will be evaluated to identify the best option to detect and predict a future failure of the generator stator winding, such as Electrical Signature Analysis, Park's Vector Approach, or direct monitorization of stator temperature and insulation. Through an appropriate condition monitoring technique, a stator winding degradation model will be developed, which could assist in the sizing phase of the generator's nominal power in future designs, as well as in making decisions to modify the control law based on the degradation of the generator during the operation of the wave energy converter.Peer reviewe
STEP-BY-STEP METHOD FOR DISTRICT RENOVATION THROUGH COMMUNITY ENGAGEMENT AND URBAN PLANNING TO FOSTER LOCAL ECONOMIC DEVELOPMENT AND IMPROVE THE QUALITY OF LIFE
Get PDFPublisher Copyright: © 2024 WIT Press.Reaching environmental targets set by the European Union (EU) requires, among other intervention areas, the energy renovation of the existing building stock. Current studies show that the renovation rate is more than two times less than what is necessary to reach the targets. Most implemented renovations across the EU reach just a small amount of energy savings. At the same time, their built environment presents habitability and accessibility problems which require regeneration processes at the district scale. In any case, the renovation rates are low to reach EU targets and milestones for 2030, 2040 and 2050. Therefore, an integral renovation process supporting district-level approaches to renovation could help if it addresses the quality of the urban space, the urban accessibility, and the social and economic challenges. Moreover, such processes need to be carried out through a participatory approach to cultivate active engagement and collaboration among community members, thereby enhancing the sustainability of renovation initiatives. This paper proposes an integrated renovation methodology for guaranteeing and fostering an integral renovation approach by providing decision-makers and stakeholders with sound support concerning the identification, selection and prioritisation of the renovation initiatives. The proposed methodology is rooted in well-established step-based methods which contemplate human-centred approaches to technology development with social innovation guaranteeing citizens’ participation and engagement. The methodology is demonstrated using a case study in Spain. The main outcomes demonstrate that the characterisation of both the buildings of the neighbourhood (and its physical diagnosis) and the neighbour’s profile allows for effectively anticipating the needs of the residents concerning the neighbourhood and buildings. The ultimate purpose is to provide recommendations and lessons learned for its replicability in neighbourhoods with similar characteristics since the method paves a promising basis for assessing district-scale energy renovation alternatives.Peer reviewe
Microstructure and mechanical properties of Al/TiC and Al/(Ti,W)C nanocomposites fabricated via in situ casting method
Get PDFPublisher Copyright: © 2023 The AuthorsA modified self-propagating high-temperature synthesis in bath (SHSB) via cast was successfully used to produce the aluminium-based composites reinforced by TiC and (Ti,W)C nanoparticles. The process was managed by the addition of a moderator affecting supercooling, which consequently influences the nucleation and growth of TiC crystals. Thus, by choosing the suitable amount of moderator, not only the size and amount but also the distribution of the strengthening particles can be controlled. In this work, the research was performed in a twin-track approach: fabrication of good quality TiC particles with a homogenous distribution inside of the aluminium matrix (1), and modification of TiC particles by the addition of W in order to improve the coherency degree between both particles and the matrix and ensure more uniform distribution of the reinforcement (2). Moreover, the homogenous microstructure of Al/TiC composites was obtained. TiC particles were uniformly distributed, and no cluster in the matrix in composite up to the highest moderator content (80 wt%) was found. The compressive strength and hardness of composites reinforced with TiC particles have been significantly improved (over 100 %) compared to the base alloy while the highest values were achieved for the composite containing 80 wt% of the moderator. Moreover, the addition of W causes a significant change in the lattice parameters of TiC at the interface without changing its face-centered cubic structure (fcc). This in turn leads to improved coherence at the particle/matrix interface.Financial support of the National Science Centre, Poland (project no. 2021/43/B/ST8/03271 ) is greatly acknowledged. A. Wójcik and A. A. Jimenez Zabaleta are grateful for the financial support of a KMM-VIN Research Fellowship from the European Virtual Institute ( https://www.kmm-vin.eu/fellowships/ ).Peer reviewe
On generating trustworthy counterfactual explanations
Get PDFPublisher Copyright: © 2023 The Author(s)Deep learning models like chatGPT exemplify AI success but necessitate a deeper understanding of trust in critical sectors. Trust can be achieved using counterfactual explanations, which is how humans become familiar with unknown processes; by understanding the hypothetical input circumstances under which the output changes. We argue that the generation of counterfactual explanations requires several aspects of the generated counterfactual instances, not just their counterfactual ability. We present a framework for generating counterfactual explanations that formulate its goal as a multiobjective optimization problem balancing three objectives: plausibility; the intensity of changes; and adversarial power. We use a generative adversarial network to model the distribution of the input, along with a multiobjective counterfactual discovery solver balancing these objectives. We demonstrate the usefulness of six classification tasks with image and 3D data confirming with evidence the existence of a trade-off between the objectives, the consistency of the produced counterfactual explanations with human knowledge, and the capability of the framework to unveil the existence of concept-based biases and misrepresented attributes in the input domain of the audited model. Our pioneering effort shall inspire further work on the generation of plausible counterfactual explanations in real-world scenarios where attribute-/concept-based annotations are available for the domain under analysis.This work has received funding support from the Basque Government (Eusko Jaurlaritza) through the Consolidated Research Group MATHMODE ( IT1256-22 ) and by the “Centro para el Desarrollo Tecnologico Industrial” (CDTI) and the European Union (AI4ES project, grant no. CER-20211030 ). Parts of this work have been funded by the Austrian Science Fund (FWF), Project: P-32554 . Parts of this work have received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 826078 (Feature Cloud). This publication reflects only the authors' view and the European Commission is not responsible for any use that may be made of the information it contains. N. Díaz-Rodríguez was supported by the Spanish Government Juan de la Cierva Incorporación contract ( IJC2019-039152-I ), the Google Research Scholar Programme 2021 and a Marie Skłodowska-Curie Actions (MSCA) Postdoctoral Fellowship with agreement ID: 101059332 .Peer reviewe
Connected and Intelligent Framework for Vehicle Automation in Smart-Ports
Get PDFPublisher Copyright: AuthorsThe increase in maritime traffic due to the globalization of trade has led to an exponential growth in logistics operations and port traffic management is becoming increasingly complicated. The need to improve the efficiency, safety, and sustainability of operations is leading to a strong demand for automation in port processes. A significant challenge is the optimization and automation of loading and unloading systems, given their complexity and repetitive nature. Advances in automated systems, through ongoing research and application in various transportation scenarios, are addressing these challenges. However, automating vehicles alone is insufficient; it is also important to have a connected, infrastructure-based collaborative framework to manage the complex logistics of port operations effectively and in a synchronized manner. In this sense, ESTIBA+2022, a Spanish-funded project, is addressing this challenge, aiming to develop strategic technologies for Smart-Ports. Its goal is to design and validate a scalable collaborative framework that meets the specifications and functions of port services using Industry 4.0 technologies and advanced wireless communications through Connected Intelligent Transportation Systems (C-ITS). This article presents the proposed architecture and its validation in the comprehensive use case of the project, focusing on communication from the supervision platform to Automated Guided Vehicles (AGVs) to ensure optimal traffic flow and management in ports. Specifically, the scenario involves three different forklifts equipped with an On-Board Unit (OBU) that interact with each other and the infrastructure via Roadside Units (RSU). The outcome of the project shows that the framework can meet the requirements for Smart-Port logistics, showing the feasibility of the implementation with a collaborative maneuver between three forklifts, a supervision station, and connected traffic lights.Peer reviewe
Analysis of the machining process of short carbon fiber-reinforced polyamide additive manufactured parts
Get PDFPublisher Copyright: © 2024 The Author(s)In recent years, additive manufacturing technologies have revolutionized the production of parts, particularly in the aeronautical sector. This new manufacturing paradigm has created significant challenges and opportunities for researchers in materials and manufacturing processes. One important aspect is the development of optimal strategies for finishing-oriented machining of parts produced through additive manufacturing. This article focuses on the analysis of reinforced polyamide materials and the integration of large-scale additive manufacturing using Big Area Additive Manufacturing (BAAM) technology, along with robotic systems for subtractive machining. The aim is to explore the potential of integrating additive and subtractive processes to produce high-quality, large-scale components. The study examines the production and subsequent machining of reinforced polyamide parts using BAAM technology, showcasing the advantages and promising results observed. By combining additive manufacturing with subtractive machining, this research contributes to the ongoing advancements in the field of manufacturing, particularly in relation to reinforced polyamide materials. The findings presented in this article shed light on the potential of integrating additive and subtractive processes in the manufacturing industry, paving the way for more efficient and high-quality production methods.Peer reviewe
Functionality of macrophages encapsulated in porcine decellularized adipose matrix hydrogels and interaction with Candida albicans
Get PDFPublisher Copyright: © 2024 The AuthorsExtracellular matrix hydrogels are considered one of the most suitable biomaterials for tissue regeneration due to their similarity with the extracellular microenvironment of the native tissue. Their properties are dependent on their composition, material concentration, fiber density and the fabrication approaches, among other factors. The encapsulation of immune cells in this kind of hydrogels, both in absence or presence of a pathogen, represents a promising strategy for the development of platforms that mimic healthy and infected tissues, respectively. In this work, we have encapsulated macrophages in 3D hydrogels of porcine decellularized adipose matrices (pDAMs) without and with the Candida albicans fungus, as 3D experimental models to study the macrophage immunocompetence in a closer situation to the physiological conditions and to mimic an infection scenario. Our results indicate that encapsulated macrophages preserve their functionality within these pDAM hydrogels and phagocytose live pathogens. In addition, their behavior is influenced by the hydrogel pore size, inversely related to the hydrogel concentration. Thus, larger pore size promotes the polarization of macrophages towards M2 phenotype along the time and enhances their phagocytosis capability. It is important to point out that encapsulated macrophages in absence of pathogen showed an M2 phenotype, but macrophages coencapsulated with C. albicans can switch towards an M1 inflammatory phenotype to resolve the infection, depending on the fungus quantity. The present study reveals that pDAM hydrogels preserve the macrophage plasticity, demonstrating their relevance as new models for macrophage-pathogen interaction studies that mimic an infection scenario with application in regenerative medicine research.Peer reviewe
Improving the OWC Wave Energy Converter Power Take-Off Efficiency throughout Experimental and Numerical Characterisation of an SCIG
Get PDFPublisher Copyright: © 2024 by the authors.The increasing interest in the use of renewable energy technologies is directing attention towards the potential contribution of marine energy technologies, especially ocean wave energy, to world energy demand. While open-sea demonstrations of full-scale devices have been carried out to validate several technologies, the focus now is shifting to optimising the components for efficiency and reliability. The efficiency of the electrical generator plays a crucial role in wave-to-wire numerical models for converting wave energy into usable electricity. It provides essential data that enables the industry to reduce technical risks and uncertainties. Wave-to-wire models typically simplify the generator’s efficiency through assuming a single curve based on the load. This curve is usually provided by the machine manufacturers for the nominal rotational speed. However, the rotational speed varies in the case of air turbines used in OWC devices. Therefore, to accurately estimate decision variables derived from these models, a comprehensive efficiency map is necessary. This map should demonstrate the performance at different rotational speeds and loads, as it directly influences the estimation of key parameters. The main objective of the present work is to improve the generator behaviour of an OWC for different generator operation regimes. For this purpose, a numerical model of the generator’s efficiency will be developed throughout the segregation of losses and validated experimentally. Finally, an optimal control law will be presented to maximise the electrical power output of the wave energy converter, considering the efficiency of both the generator and the turbine.Peer reviewe
MEDINA Catalogue of Cloud Security controls and metrics: Towards Continuous Cloud Security compliance
Get PDFPublisher Copyright: Copyright: © 2024 Martinez C et al.In order to address current challenges on security certification of European ICT products, processes and services, the European Comission, through ENISA (European Union Agency for Cybersecurity), has developed the European Cybersecurity Certification Scheme for Cloud Services (EUCS). This paper presents the overview of the H2020 MEDINA project approach and tools to support the adoption of EUCS and offers a detailed description of one of the core components of the framework, the MEDINA Catalogue of Controls and Metrics. The main objective of the MEDINA Catalogue is to provide automated functionalities for CSPs’ compliance managers and auditors to ease the certification process towards EUCS, through the provision of all information and guidance related to the scheme, namely categories, controls, security requirements, assurance levels, etc. The tool has been enhanced with all the research and implementation works performed in MEDINA, such as definition of compliance metrics, suggestion of related implementation guidelines, alignment of similar controls in other schemes, and a set of self-assessment questionnaires, which are presented and discussed in this paper.Peer reviewe