Search Results (394)

This study examines the in-plane compression behavior of sandwich panels produced with additive manufacturing. This study focuses on two types of honeycomb unit cell topologies with larger dimensions: a hexagonal one and a re-entrant one. For each panel geometry, two material configurations were examined: Onyx (a nylon-based composite) and Onyx reinforced with 10% continuous carbon fibers (CCFs) by mass. The objective was to assess the influence of fiber reinforcement on the mechanical performance and deformation response of the panel structures. In-plane compression tests were conducted to determine the stiffness, strength, and failure modes of the specimens. Additionally, the digital image correlation (DIC) technique was used to capture full-field strain distributions and analyze local deformation mechanisms during loading. The results revealed distinct mechanical responses between the two geometries: the re-entrant structure exhibited auxetic behavior and enhanced energy absorption characteristics. Although reinforced honeycomb panels have an average load capacity that is 35% higher, they fail at a displacement that is approximately 55% smaller compared to unreinforced panels. Despite accounting for only 25% of the total number of layers and 10% of the panel’s mass, the reinforcement achieved superior strength. Re-entrant panel testing showed a 25% force increase in favor of the reinforced variant. They fail at a displacement that is 36.5% greater than that of reinforced honeycombs. This demonstrates a more compliant response while also maintaining 4.9% greater strength, indicating the superior behavior of auxetic reinforced sandwich panels. Introducing CCF reinforcement increased the load-bearing capacity and reduced localized strain concentrations without altering the overall deformation pattern. These findings suggest that enhancing materials can increase the strength and flexibility of 3D-printed re-entrant structures, providing valuable insights for lightweight design and optimized material use in structural applications. Full article

Sustainable urban energy is based on innovative solar and wind solutions. The paper presents such a hybrid solar–wind system, which is easy to place on building terraces, highlighting the advantages of this technical solution: energy production as close as possible to consumers, the elimination of system losses, and small installation spaces being required. The system operates well in the low-speed range for the horizontal axis crossflow wind turbine placed under a flexible solar panel, at speeds between 2 and 8 m/s, and exhibits good efficiency in cooling the photovoltaic panels. The prototype proposed by the paper is a small-scale model that can produce on average 400 Wh/day and about 150 kWh/year. The paper analyses numerically the aerodynamic behaviour of the prototype at several wind speeds, as well as experimental results regarding the power and power coefficient for the wind turbine, as well as the power and efficiency of the flexible solar panel in the hybrid system. The research is complemented with comparative technical analysis and economic analysis. Full article

Innovative learning environments such as IkasLab demand evaluation instruments that connect spatial design with pedagogical, cognitive, and technological dimensions; however, no validated tools currently address this need. This study aimed to develop and validate a rubric for assessing IkasLab classrooms, conceived as active learning environments that foster cognitive and metacognitive processes. A two-round Delphi study was conducted with a panel of 13 experts in learning spaces, cognitive processes, and ICT. Quantitative assessments and qualitative contributions were analysed, and the expert competence index (K = 0.835) confirmed a high level of expertise and consensus. The resulting rubric is organised into four blocks—social learning spaces, learner-centred environments, spaces for reflective thinking, and spaces for deep learning—each linked to specific cognitive processes derived from established theoretical frameworks. The validated instrument offers a structured and coherent framework for examining how spatial, cognitive, and technological components interact within IkasLab environments. The findings contribute theoretically by articulating a model that associates physical learning spaces with cognitive processes, and practically by providing an evidence-based tool for teachers, designers, and policymakers seeking to evaluate or implement active, flexible, and cognitively oriented learning environments. Full article

Cold-formed thin-walled steel (CFS) members were widely used in steel structures but faced challenges in meeting bearing capacity and assembly efficiency requirements as single-limb members. To overcome the above limitations, a promising fold-fastened multi-cellular steel panel (FMSP) was proposed. The FMSP eliminated the need for discrete self-drilling screws, instead utilizing a continuous mechanical fold-fastened connection, which enhanced structural integrity and assembly efficiency. This approach also provided greater flexibility to meet the design requirements of complex structural configurations. This study investigated the flexural behaviors of panels—a key mechanical property governing their structural behavior. A bearing capacity test was conducted on five FMSP specimens, focusing on the failure modes, bending moment–deflection curves, deflection distributions under representative loading levels, and flexural bearing capacities of the specimens. Refined finite element models (FEMs) of the specimens were established, and the stress and deformation distributions were further studied. The comparison results showed that the numerical results were in good agreement with the experimental results. Finally, the parametric analysis was carried out, and the influence of key parameters on the flexural behavior was revealed. Analysis results demonstrated that doubling the steel plate thickness increased the flexural capacity by 207%, while a twofold increase in panel thickness resulted in a 123% improvement. In contrast, increasing the steel strength from 235 MPa to 460 MPa yielded only a 61% enhancement. This research laid a solid foundation for promoting the application and investigation of FMSPs, thus achieving high industrialization and meeting the requirements of complex structural design. Full article

This study presents the design and implementation of a prototype dual-function photovoltaic window system that integrates flexible solar panels for dynamic shading and a compact lithium battery for local energy storage. The methodology involves developing an experimental setup where translucent, flexible photovoltaic panels are retrofitted onto a standard residential window. The system is connected to a charge controller and a small-capacity lithium-ion battery pack. Key performance metrics, including solar irradiance, power generation efficiency, reduction in thermal transmittance, and battery state of charge, are continuously monitored under varying real-world environmental conditions. The integrated panels can significantly reduce solar heat gain, thereby lowering indoor ambient temperature and reducing the building’s cooling load. Simultaneously, the system will generate sufficient electricity to be stored in the lithium battery, providing a self-contained power source for low-draw applications such as lighting or charging personal devices. This research highlights the viability of developing cost-effective, multi-functional building components that transform passive architectural elements into active energy-saving and power-generating systems in terms of green environment goals. Full article

In the area of the European Union (EU) energy policy, among the entities involved in the process of financing investments in renewable energy sources (RESs), the European Investment Bank (EIB) plays a particularly important role. Therefore, the aim of the research was to identify the relationship between the EIB’s financing of RES projects and the level of energy transition, measured by the share of RES in gross final energy consumption (RE). The goal was achieved using quantitative methods and a two-way fixed-effects panel model FE (country and year), based on data from EIB, Eurostat, World Bank, OECD, EDGAR, and Our World in Data for 2012–2023. As a result of the research, it was determined that the scale of EIB financing alone does not translate into short-term growth of the RE in the examined sample (EU countries). Indeed, the effectiveness of funding depends on the regulatory and institutional context; the grid’s ability to absorb new capacities (throughput, storage, demand flexibility); and from the time horizon (delayed materialization of effects). Increasing the efficiency of converting euros into RE percentage points requires better targeting (power + grid), simplification of procedures and good financial assembly with the right allocation of risks. Full article

The increasing scale and operational complexity of cyberattacks have exposed the limitations of static taxonomies for representing multistage threat scenarios. This study addresses the need for more flexible classification models by proposing a relational taxonomy of cyberattacks grounded in documented incidents. Therefore, the main objective is to propose a relational taxonomy that encodes direct transitions across eight groups in a dependency matrix and a directed graph while preserving traceability to MITRE ATT&CK. The taxonomy was validated by an independent panel of experts who assessed methodological clarity and operational utility. The results reveal consistent transition patterns across groups, delineate reproducible escalation routes, and pinpoint cut-off points linked to specific detection and control activities, providing an operational map of progression and intervention. The conclusions show that the taxonomy clarifies escalation paths, strengthens alignment across security monitoring and incident response functions, threat intelligence workflows and training, and provides an operational structure to manage interdependencies, anticipate escalation and focus monitoring on critical points. Full article

The rapid growth of renewable energy integration in modern power systems brings new challenges in terms of stability and quality of electricity supply. Hybrid AC/DC microgrids represent a promising solution to integrate photovoltaic panels (PV), wind turbines, fuel cells, and storage units with flexibility and efficiency. However, maintaining adequate power quality (PQ) under variable conditions of generation, load, and grid connection remains a critical issue. This paper presents the modelling, implementation, and validation of a hybrid AC/DC microgrid equipped with a fuzzy-logic-based energy management system (EMS). The study combines PQ assessment, measurement architecture, and supervisory control for technical compliance and economic efficiency. The microgrid integrates a combination of PV array, wind turbine, proton exchange membrane fuel cell (PEMFC), battery storage system, and heterogeneous AC/DC loads, all modelled in MATLAB/Simulink using a physical-network approach. The fuzzy EMS coordinates distributed energy resources by considering power imbalance, battery state of charge (SOC), and dynamic tariffs. Results demonstrate that the proposed controller maintains PQ indices within IEC/IEEE standards while eliminating short-term continuity events. The proposed EMS prevents harmful deep battery cycles, maintaining SOC within 30–90%, and optimises fuel cell activation, reducing hydrogen consumption by 14%. Economically, daily operating costs decrease by 10–15%, grid imports are reduced by 18%, and renewable self-consumption increases by approximately 16%. These findings confirm that fuzzy logic provides an effective, computationally light, and uncertainty-resilient solution for hybrid AC/DC microgrid EMS, balancing technical reliability with economic optimisation. Future work will extend the framework toward predictive algorithms, reactive power management, and hardware-in-the-loop validation for real-world deployment. Full article

Therapeutic peptides are a unique drug class due to their high-specificity binding with biological targets. However, the low bioavailability of peptides, as well as the lack of enzymatic stability, imposes a number of limitations on their biomedical application. A good strategy by which to overcome these limitations is the use of peptidomimetics, which are able to imitate the binding and activity of peptides both in vitro and in vivo. Peptidomimetics can be obtained by combining natural and synthetic amino acids in a peptide sequence. Various five-membered heterocycles are often used as structural fragments of peptide imitators to fix the chain in a certain conformation and to increase proteolytic stability. The use of 5-aminomethyl-1,2,4-triazole-3-carboxylic acid derivatives as building blocks of peptidomimetic structures may be a very attractive strategy, in which the tautomeric 1,2,4-triazole fragment is capable of flexibly forming hydrogen bonds on the protein surface of the target. In this work, a number of ethyl 5-aminomethyl-1,2,4-triazole-3-carboxylates and their derivatives were synthesized as mimetics of aliphatic amino acids. Their use as building blocks for synthesizing peptidomimetics was demonstrated. In addition, through the use of a panel of pathogenic and model strains of microorganisms and fungi, we demonstrated the lack of independent activity of the amino acid 1,2,4-triazole mimetics synthesized. This similarity of the biological properties of the obtained mimetics and their natural analogues reveals their bioisosterism. The bioisosterism and geometric similarity of 1,2,4-triazole mimetics and natural amino acid highlights the potential of their use as building blocks for therapeutic peptides. Full article

This study evaluated the feasibility of culturing Seriola lalandi in a low-cost recirculating aquaculture system (RAS) in an arid region of northern Chile, aiming to establish strategies for broodstock farming and diversify national aquaculture. The system was designed as a low-cost recirculating aquaculture system (RAS) built with locally available materials, such as galvanized corrugated steel panels and flexible plastic liners, instead of specialized aquaculture tanks. Its modular configuration, based on gravity-fed filtration using sedimentation, sand, and disc filters, allows efficient water reuse with minimal energy consumption and a daily water turnover of 12 times the total volume. This design significantly reduced construction and operational costs, making it a feasible option for aquaculture development in arid regions with limited water resources. Over an 8-month period, 46 S. lalandi individuals were used, and the results showed successful physiological adaptation of the specimens to confinement, as evidenced by low mortality, progressive acceptance of formulated feed, and sustained growth. Individual weights progressively increased, with averages ranging from 675 to 1435 g, and the specific growth rate (SGR) fluctuated between 0.14 and 0.43% per day. Fulton’s condition factor (K) remained in an adequate range between 2.4 and 2.8, suggesting good physical condition of the sampled individuals. Water quality within the RAS system was maintained within acceptable parameters, although a strong negative correlation between temperature and dissolved oxygen was recorded (Spearman coefficient = −0.71, p < 0.001), highlighting the importance of monitoring these factors in warm environments. The lack of adequate protocols for the adaptation of marine species in arid areas, such as northern Chile, has limited aquaculture development in these regions. This study addresses this problem by assessing the feasibility of a low-cost recirculating system (RAS) for the cultivation of S. lalandi under conditions of water scarcity, with the aim of diversifying the national aquaculture in arid zones. Full article

As coal-fired power plants shift from being primary power sources to operating as flexible peak-shaving units, the reheater—a critical component of the boiler’s ‘four tubes’—has attracted significant attention. This study focuses on the tube wall temperature distributions of the reheater at different loads and measurement points, analyzing factors that contribute to its uneven heat distribution. The results indicate that the heat distribution across the tubes of the low temperature reheater (LRH) is uneven. From the left to the right side of the tube panel, the tube wall temperatures form two parabolic profiles. The tubes most susceptible to overheating are the first tube of the 91st panel and the first tube of the 181st panel. For the high-temperature reheater (HRH), at an electrical load of 217.7 MW, the maximum temperature difference is higher than that of LRH. At all other electrical loads, however, the maximum temperature difference of the HRH is lower than that of the LRH. The LRH is at a higher risk of tube rupture caused by uneven heating compared to the HRH. Full article

Rapid decarbonization relies on knowing which structural and energy factors affect national carbon dioxide emissions. Much of the literature leans on linear and additive assumptions, which may gloss over curvature and interactions in this energy–emissions link. Unlike previous studies, we take a different approach. Using a panel of 80 high- and upper-middle-income countries from 2011 to 2020, we model emissions as a function of fossil fuel energy consumption, methane, the food production index, renewable electricity output, gross domestic product (GDP), and trade measured as trade over GDP. Our contribution is twofold. First, we evaluate how different modeling strategies, from a traditional Generalized Linear Model to more flexible approaches such as Support Vector Machine regression and Random Forest (RF), influence the identification of emission drivers. Second, we use Double Machine Learning (DML) to estimate the incremental effect of fossil fuel consumption while controlling for other variables, offering a more careful interpretation of its likely causal role. Across models, a clear pattern emerges: GDP dominates; fossil fuel energy consumption and methane follow. Renewable electricity output and trade contribute, but to a moderate degree. The food production index adds little in this aggregate, cross-country setting. To probe the mechanism rather than the prediction, we estimate the incremental role of fossil fuel energy consumption using DML with RF nuisance functions. The partial effect remains positive after conditioning on the other covariates. Taken together, the results suggest that economic scale and the fuel mix are the primary levers for near-term emissions profiles, while renewables and trade matter, just less than is often assumed and in ways that may depend on context. Full article

Risk identification is a foundational process in construction project management, yet the selection of appropriate identification techniques often lacks empirical guidance. To address this gap, this study adopts a case study design and conducts a comparative evaluation of four established but underutilized methods—Delphi, Nominal Group Technique (NGT), Hazard and Operability Study (HAZOP), and Preliminary Hazard Analysis (PHA)—within the context of a large-scale infrastructure project in Türkiye. The Delphi panel consisted of five senior experts. The NGT session involved six site-level practitioners, and the HAZOP team was composed of four multidisciplinary professionals. Two project-level managers conducted the PHA. Each technique was assessed against seven evaluative criteria: methodological structure, stakeholder engagement, analytical depth, resource intensity, flexibility, decision-support value, and contextual fit. The findings reveal that HAZOP achieved the highest analytical depth and decision-support capacity, while NGT demonstrated the strongest stakeholder engagement and contextual adaptability. Delphi provided robust systemic insights but required substantial time and expert availability, whereas PHA offered rapid screening capacity with limited depth. Drawing on these findings, the study proposes a Contextual Decision Support Model that helps practitioners select the most suitable technique based on project complexity, available resources, and stakeholder conditions. This practical framework enables construction professionals to balance methodological rigor with contextual feasibility, ensuring that risk identification processes are both systematic and adaptable to real-world constraints. Beyond its methodological contribution, the study advances risk management in construction by providing a structured and transparent decision-support approach that bridges academic rigor with on-site practice. By aligning method selection with project-specific attributes and stakeholder dynamics, the model strengthens the integration of analytical precision and practical decision-making across the project lifecycle, thereby contributing to more proactive, evidence-based, and resilient risk management in construction projects. Full article

This study aims to explore how organizations plan and implement flexible work arrangements (FWAs) to support managers in fostering work–family balance. In doing so, we examine the sequential mediating roles of work–family conflict, CEO gender equality perceptions, and organizational commitment to elucidate the consequences of FWAs. Our study draws upon the Korean Women Manager Panel (KWMP), a three-year initiative that includes 2345 mother and father managers working in 469 Korean companies. We utilized the longitudinal multilevel macro process model 8 to examine the mediating effects of work–family conflict and CEO gender equality perceptions on the relationship between FWAs and organizational commitment. The findings show that both work–family conflict and CEO gender equality perceptions mediate the relationship between FWAs and organizational commitment. Notably, father managers perceive less work–family conflict than mother managers, which indicates that as FWAs increase, CEO gender equality perceptions and organizational commitment rise as well. The use of FWAs is more beneficial for father managers as it alleviates work–family conflict and fosters positive perceptions and attitudes about CEOs and organizations. Thus, to increase the effectiveness of FWAs, it is pivotal to consider managers’ gender. Additionally, the CEO must be actively involved in shaping and promoting gender equality in the workplace. Full article

This article presents the manufacturing technology and mechanical properties of innovative pre-impregnated coatings (PCs). The base materials for PC are powders of metal oxides, non-metals, minerals and thermoplastic non-wovens. PC can be used in the manufacture of composites by methods such as vacuum infusion, autoclave curing or hand lamination. This is possible due to the novel PC structure consisting of a functional layer (FL) and a backing layer (BL). PCs are flexible so that they can be used on curved surfaces. In this work, five types of PC were subjected to a uniaxial tensile test. Depending on the powder used, failure force values ranging from 24.61 N to 28.73 N were obtained. In the next step, the pre-impregnated coatings were applied as a coating in “sandwich” composites made by vacuum infusion, which were subjected to three-point bending (3-PB) and adhesion tests. 3-PB tests proved that the coating remained integral with the substrate, even under high flexural deformation, while the adhesion achieved was in the range of 0.95 MPa to 1.57 MPa. PC can be used in many engineering products, e.g., for the coating of façade panels, roof tiles, automotive parts or rail vehicles, etc. Full article