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Analysis of Planar Double-Layer Timber Spatial Frames by Using Parametric Tools
Get PDFPublisher Copyright: © 2024 by the authors.It is in the preliminary design phase of a project that the designer makes decisions concerning the global geometry of the structure. When working with space frames, the choice of the frame topology is key for the structural behavior. It is difficult to find manuals that provide guidance on which of the most common topologies is the right one for the project, let alone in wood construction. In response to this shortcoming, the use of parametric software is proposed (Grasshopper build1.0.0007 and Karamba 3D 2.2.0.16-220828). The aim is to create a dynamic catalog that responds instantaneously to changes in the parameters to provide information on structural behavior, pre-dimensioning and metrics. With the display of all this information, the architect will have enough technical argumentation to choose or reject options. The proposal is developed through a case study: the early design and analysis stages of flat double-layer timber spatial frames as for rectangular medium-span roofs.Peer reviewe
Structural safety assessment criteria for dismantling operations of unique structures. San Mames Roof Arch Experience
Get PDFPublisher Copyright: © 2024 The AuthorsDismantling is a fundamental phase of the life cycle on transport infrastructures and buildings in terms of sustainability and environmental impact but also in terms of structural safety. The requirements of the dismantling operation of a structure are linked to the complexity of the structure, and it is necessary to monitor the evolution of its structural behavior to avoid unexpected and demanding conditions and facilitate it reuse in the future. The authors present (1) an optimal methodology for the approach to the dismantling project of a structure, (2) a new global structural safety indicator for real time assessment, as well as (3) its application in the dismantling of the San Mames arch roof. The application of the vibrating chord technique in order to obtain the existing stresses in the lower tie rod of the arch of the San Mames roof arch and the monitoring of the evolution of the stresses in this tie rod during the operation of lifting and dismantling of the roof arch is presented. As a result, the paper contributes to reducing the lack of shared experience in the sector, as it is one of the few in the literature on the dismantling of large structural elements.Peer reviewe
Exploring Data Augmentation and Active Learning Benefits in Imbalanced Datasets
Get PDFPublisher Copyright: © 2024 by the authors.Despite the increasing availability of vast amounts of data, the challenge of acquiring labeled data persists. This issue is particularly serious in supervised learning scenarios, where labeled data are essential for model training. In addition, the rapid growth in data required by cutting-edge technologies such as deep learning makes the task of labeling large datasets impractical. Active learning methods offer a powerful solution by iteratively selecting the most informative unlabeled instances, thereby reducing the amount of labeled data required. However, active learning faces some limitations with imbalanced datasets, where majority class over-representation can bias sample selection. To address this, combining active learning with data augmentation techniques emerges as a promising strategy. Nonetheless, the best way to combine these techniques is not yet clear. Our research addresses this question by analyzing the effectiveness of combining both active learning and data augmentation techniques under different scenarios. Moreover, we focus on improving the generalization capabilities for minority classes, which tend to be overshadowed by the improvement seen in majority classes. For this purpose, we generate synthetic data using multiple data augmentation methods and evaluate the results considering two active learning strategies across three imbalanced datasets. Our study shows that data augmentation enhances prediction accuracy for minority classes, with approaches based on CTGANs obtaining improvements of nearly 50% in some cases. Moreover, we show that combining data augmentation techniques with active learning can reduce the amount of real data required.Peer reviewe
A methodology to assess circular economy strategies for sustainable manufacturing using process eco-efficiency
Get PDFPublisher Copyright: © 2024 The AuthorsA growing number of companies engage in sustainability, with early adopters already realizing financial and environmental benefits. However, the current linear production model followed by most manufacturers is widely recognized as not being sustainable. The circular economy model can be an eco-friendly alternative to production and consumption, ensuring a smooth transition to sustainable practices. In this study, the impact of various sustainable practices in manufacturing is reviewed as well as the impact of life cycle assessment in the quantification of the impact of the sustainable practices. However, a simple and fast methodology for manufacturers to get a first indication about the potential improvements in their production lines and required changes for adopting circular economy practices is missing from the literature. The main objective of this study is to provide a quantified methodology that facilitates decision-making at a manufacturing process and system level regarding the adoption of more sustainable strategies. An eco-efficiency indicator is proposed targeting the reduction of energy consumption and manufacturing waste caused by production operations, on top of the life cycle assessment and cost analysis of a process. The indicator combines a process's environmental performance, whose calculation is performed using life cycle assessment studies, and the process's value performance, whose calculation is derived from a combination of a life cycle costing analysis with the process and product-related metrics encapsulated under the umbrella of the overall equipment effectiveness, and of a cost of implementation metrics signifying the required cost for replacing existing equipment to adopt a circular economy strategy. Additionally, the indicator is not constrained by any geographical coverage and applies to any manufacturing use case as long as the life cycle assessment model is constructed using the ISO 14044:2006 standard. The proposed approach is examined in two industrial use cases, in which the proposed indicator is evaluated against three potential circular economy strategies for improved sustainability, the use of renewable energy sources, and material reuse.Peer reviewe
Effect of Sulphate-Reducing Bacteria Activity on the Performance of Thermally Sprayed Aluminium and Polyurethane Coatings
Get PDFPublisher Copyright: © 2024 by the authors.In the present work, we studied whether the exposure of synthetic seawater with anaerobic sulphate-reducing bacteria (SRB) on some steel samples generates a bacterial biofilm in their surfaces. Bare steel belonging to a mooring chain as well as two coating systems applied on the steel surface were studied: polyurethane (PU) and thermally sprayed aluminium (TSA) with and without an epoxy-based sealant. After 30 days of immersion in SRB-inoculated synthetic seawater, a bacterial count was attained, and the samples were observed using scanning electron microscopy (SEM) and locally analysed using X-ray scattered energy spectroscopy (EDS). A biofilm developed on every tested surface (continuous or in the form of pustules), with evidence of metabolic activity of the SRB. Finally, a mechanism of degradation for TSA in the presence of SRB is proposed for environments with a high concentration of bacteria.Peer reviewe
Leveraging Blockchain Usage to Enhance Slag Exchange
Get PDFPublisher Copyright: © 2024 by the authors.The slag generated as a by-product of the steelmaking process can be used to manufacture cement, reducing the generated waste and contributing to the circular economy. Currently, steelmaking companies promote long-term bilateral deals with one or few cement companies where the price is fixed, and the slag is a treated as commodity. We propose a new solution, which promotes slag reuse through its differentiation with a composition-based grouping and an auction. This process is carried out in a blockchain network, which increases trust in the system, provides guarantees about the slag composition to cement companies and helps external regulators to reliably extract circularity indicators.Peer reviewe
Impact of Chronic Pain on Use-Dependent Plasticity: Corticomotor Excitability and Motor Representation in Musicians With and Without Pain
Get PDFPublisher Copyright: © 2024, The Author(s).Long-term musical training induces adaptive changes in the functional representation of the motor cortex. It is unknown if the maladaptive plasticity associated with chronic pain, frequently affecting trained musicians, may alter the use-dependent plasticity in the motor cortex. This study investigated the interaction between adaptive and maladaptive plasticity in the motor pathways, in particular how chronic pain influences long-term use-dependent plasticity. Using transcranial magnetic stimulation (TMS), corticospinal excitability was assessed by measuring the amplitude of the motor-evoked potential (MEP), area of the motor map, volume, and center of gravity of the first dorsal interosseous muscle in 19 pain-free musicians, 17 upper limb/neck pain chronic pain musicians, and 19 pain-free non-musicians as controls. Motor map volume and MEP amplitude were smaller for both pain-free and chronic pain musicians compared to pain-free controls (P < 0.011). No significant differences were found between musicians with and without chronic pain. These findings confirm that long-term musical training can lead to focalized and specialized functional organization of the primary motor cortex. Moreover, the adaptive use-dependent plasticity acquired through fine-motor skill acquisition is not significantly compromised by the maladaptive plasticity typically associated with chronic pain, highlighting the potential of long-term sensorimotor training to counteract the effects of chronic pain in the motor system.Open access funding provided by Aalborg University. This study was funded by a grant from the Danish National Research Foundation (DNRF121) to the Center for Neuroplasticity and Pain (CNAP), and by a grant from the Lundbeck Foundation (R303-2018-3356) to AMZ. PV and BK are affiliated to the Center for Music in the Brain that is supported by the Danish National Research Foundation (DNRF117). HF was supported by the Deutsche Forschungsgemeinschaft (FL 156/41-1).Peer reviewe
Life cycle costing as part of a life cycle sustainability assessment of products: methodology and case studies
No full textPublisher Copyright: © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.Purpose: Existing life cycle sustainability assessments (LCSAs) suffer from a lack of comprehensiveness, consistency and practical tools for implementation. A robust and operational methodology for LCSA of products was developed in which life cycle costing (LCC) covers the economic dimension. We aim to define a comprehensive LCC methodology not tailored to a specific type of product for the purpose of LCSA and test its applicability. Methods: Based on a literature screening, best practice and research needs are identified. Subsequently, a comprehensive LCC methodology is developed that (a) suits LCSA purposes, (b) explicitly addresses double counting, (c) is applicable to different stakeholder needs, (d) addresses externalities and (e) facilitates LCC. It can be used as part of the LCSA, but also stand-alone. The LCC methodology is applied in two case studies, one on the business-to-business (B2B) “beverage carton package” and one on the consumer product “outdoor wool jacket”. Results and discussion: To align specifically with the LCSA’s environmental part, guidance for an environmental LCC for a generic product was established. While providing minimum requirements, it also allows flexibility in terms of considering discounting or positive cash flows and thus the choice of the economic indicator, depending also on the defined goal and scope, and the chosen stakeholder perspective. Practical guidance on data collection and management is provided in the form of an extended cost breakdown structure and regarding the allocation of product-unspecific costs. Double counting within LCC and within LCSA is addressed. The methodology was applied in two case studies, quantifying the “total undiscounted value” (package) and “total undiscounted cost” indicators (jacket). A solution to communicating results containing confidential data and from different stakeholder perspectives was found for the jacket case. Confidentiality and the lack of publicly available data of sufficient quality prevented the sharing of the “package” results. Conclusions: An LCC methodology for use in LCSA is developed, and its applicability is tested in two case studies. Novelties concern the methodological consideration of different stakeholder perspectives, suggesting alternative aggregated economic indicators, the proposed cost breakdown structure as an economic inventory, guidance on allocation of product-unspecific costs and addressing double counting. Data availability, including confidentiality, and quality remain barriers to publishing LCC results.Peer reviewe
High-Resolution Interannual Evolution of the Dune Toe at a Mesotidal Barrier (Camposoto Beach, SW Spain)
Get PDFPublisher Copyright: © 2024 by the authors.Over recent years, processes related to marine storms, sediment shortages and human intervention have caused the global retreat of many coastal systems and the degradation of their dunes. In this context, changes in the dune toe are commonly used as a proxy to study the interannual shoreline evolution, and it is usually analyzed using orthophotography, while high temporal- and spatial-scale resolution studies of dune toe evolution are not frequent. In this work, a quasi-monthly study of dune toe data was carried out between 2008 and 2018. These data, taken from the RTK-DGPS and UAS systems, were subjected to shoreline analysis, and they showed an average regression rate of −2.30 m/year, a higher value than the one registered until 2008 (1 m/year). This suggests an acceleration in the erosion suffered within the system, which was revealed to be more intense in the northern sector of the study area. Dune toe variability increased over the years, probably due to the presence of washover fans breaking the foredune that were reactivated and expanded during storm events. The ephemeral progradation of the dune toe was also noted, which could be explained with reference to wind events and/or beach nourishment that had been carried out over the studied period. From the analysis of the dune toe elevation, a decrease in this variable was obtained, especially in the areas affected due to washover fans. This finding is supported by the significant correlation of the dune toe elevation and erosion trend, suggesting that the areas where the dune toe was lower are prone to suffering a greater retreat. This correlation provides insight into the future evolution of the barrier, suggesting a state of degradation and a transition to a lower-resilience state.Peer reviewe
Simulating chemical mixing and molten pool shape in dissimilar welds using thermal fluid dynamics
Get PDFPublisher Copyright: © 2024 The Author(s)Estimating the properties of dissimilar metal welded joints made using modern high-energy beam techniques presents significant challenges due to the complex nature of the process. These complexities arise from the different thermal and mechanical properties of the materials involved. The properties of a welded joint are primarily determined by the element mixing and final chemical composition when two dissimilar metals are fused together, or when a dissimilar filler material is used. Hence, a representative model capable of tracking elemental distribution and temperature is essential for accurately estimating the micro-scale and macro-scale mechanical properties of the joint, thus optimising the joining process. In this work, a high-fidelity thermal fluid flow model in the multiComponentlaserbeamFoam computational fluid dynamics (CFD) solver is used to simulate the process of laser beam welding. For this purpose, the joining process of AISI 304 stainless steel with a low alloy steel filler material (G3Si1) is simulated. This framework is rigorously validated with experimental results showing the capabilities of such modelling approach. Different strategies to model the filler and material properties are explored: a stationary filler model, applied through the parent material's thickness, was found to accurately mirror experimental results. This model is then used to study the flow properties, thermocapillary effect, and diffusion on the intermixing of composition, aspects that have not been previously examined in depth. The thermocapillary forces were concluded to be the most significant, dictating the peak composition value, the shape and topology of the molten pool. Diffusion fluxes were found to be negligible and not responsible for the majority of the mixing.Peer reviewe