Search Results (504)

Accurate prediction and management of the service life of buildings and structural components are crucial for ensuring durability and economic efficiency. This paper investigates both discrete- and continuous-time Markov chains as probabilistic models for representing deterioration processes of building structures. Transition probabilities, fundamental matrices, and absorption times are computed to quantify expected lifespans and degradation pathways. Numerical simulations illustrate how state probabilities evolve, inevitably converging toward structural failure in the absence of maintenance interventions. Additionally, this study explicitly addresses uncertainties inherent in lifecycle predictions through the application of fuzzy set theory. A fuzzy Markov chain model is formulated to represent imprecise deterioration states and transition probabilities, which validate the predictable yet uncertain progression of structural deterioration through graphical analyses and fuzzy simulations. The proposed methodology, including fuzzy modeling, provides building managers and engineers with a robust analytical framework to optimize maintenance scheduling, refurbishment planning, and resource allocation for sustainable lifecycle management under uncertainty. Full article

Sustainable product development demands components that last longer, consume less energy, and can be refurbished within circular supply chains. This study introduces a digital replica-based predictive prototyping workflow for industrial crusher blades that meets these goals. Six commercially used blade geometries (A–F) were recreated as high-fidelity finite-element models and subjected to an identical 5 kN cutting load. Comparative simulations revealed that a triple-edged hooked profile (Blade A) reduced peak von Mises stress by 53% and total deformation by 71% compared with a conventional flat blade, indicating lower drive-motor power and slower wear. To enable fast virtual prototyping and condition-based maintenance, deformation was subsequently predicted using a data-efficient machine-learning model. Multi-view image augmentation enlarged the experimental dataset from 6 to 60 samples, and an XGBoost regressor, trained on computer-vision geometry features and engineering parameters, achieved R² = 0.996 and MAE = 0.005 mm in five-fold cross-validation. Feature-importance analysis highlighted applied stress, safety factor, and edge design as the dominant predictors. The integrated method reduces development cycles, reduces material loss via iteration, extends the life of blades, and facilitates refurbishment decisions, providing a foundation for future integration into digital twin systems to support sustainable product development and predictive maintenance in heavy-duty manufacturing. Full article

To address incomplete die filling, high cracking tendency, and severe die wear in the conventional forging of AISI-410 martensitic stainless steel U-shaped forgings, an optimized billet volume pre-allocation strategy was proposed. Two improved forging schemes for the U-shaped forgings were designed: the Arc Concave Flattening Scheme (adding arc-shaped concave features to the flattening die for corner volume compensation) and Preformed Volume Allocation Scheme (incorporating a preforming step for strategic volume pre-allocation at ends and corners). Finite Element Analysis employing the Oyane damage model and Archard wear model was employed to simulate and optimize the forging process. The optimal scheme was applied to production trials. The results demonstrated that the Preformed Volume Allocation Scheme significantly improved the geometric compatibility between the billets and the final forging die cavity. As a result, the billet’s temperature, strain, and equivalent stress uniformity increased, reducing cracking tendency. Moreover, the rise in the mitigated temperature and stress concentration resulted in reduced final forging die wear. Production trials confirmed a qualified rate of ~96% (34% higher than the Original Scheme). The final forging die service life reached 300 pieces per refurbishment cycle, showing a 50% improvement. This work provides theoretical and practical guidance for optimizing the forging processes of complex martensitic stainless steel components. Full article

Offsite construction (OSC) offers a promising alternative for accelerating refurbishment projects across Italy and Europe. However, its adoption remains limited due to technical, regulatory, and cultural barriers. This study, conducted as part of the OFFICIO project, maps the current European OSC landscape, with a focus on wood and light-steel technologies for sustainable building refurbishment. Combining a literature review, analysis of funded projects, and market data for 541 OSC products, the study develops tailored KPIs to assess these products’ technical maturity, prefabrication level, and environmental integration. The results reveal that wood-based OSC, although less widespread, is more mature and centered on the use of multi-layer panels, while steel-based systems, though more prevalent, remain largely tied to semi-offsite construction, indicating untapped development potential. Research efforts, especially concentrated in Mediterranean regions, focus on technological integration of renewable energy systems. A significant literature gap was identified in information concerning panel-to-wall connection, critical for renovation, limiting OSC’s adaptability to regeneration of existing buildings. The findings highlight the need for cross-sector collaboration, legislative clarity, and better alignment of public procurement standards with OSC characteristics. Addressing these issues is essential to bridge the gap between research prototypes and industrial adoption and accelerate the sustainable transformation of Europe’s construction sector to help meet climate neutrality targets. Full article

Consumers’ growing interest in sustainability and the consideration of purchasing second-hand products present conditions for developing and improving a new method for Remaining Value (RV) estimation. The remaining value refers to the value of an end-of-life product that has been inspected, repaired, if necessary, and prepared for resale. Through the literature review, the main blockers, trustworthiness, price, and quality, were identified as preventing consumers from purchasing used products. Trustworthiness could be ensured by evaluating used products in an automated and model-based manner. To enhance consumers’ confidence, this study proposes a novel framework to assess the remaining value of non-new products by incorporating the diagnostic test results, even in the absence of a gold standard for model comparison and evaluation. This research expands the application of the Hui–Walter method beyond medical diagnostics by adapting it to sustainability-focused estimation. The proposed framework is designed to assist consumers in making data-informed purchase decisions and support retailers in assessing the market price while contributing to the environmental pillar of sustainability by reducing waste and resource consumption and extending the product lifetime. This work aligns with the United Nations Sustainable Development Goals 12 (Responsible Consumption and Production) and 13 (Climate Action) by providing quantifiable methods to extend the product lifecycle and minimize electronic waste. While this study focuses on developing the theoretical framework, future work will apply and validate this framework using empirical case studies and compare it with the remaining value estimation models. Full article

The world is facing unprecedented sustainability challenges, and the circular economy (CE) can provide some solutions to promote more sustainable practices among companies. This study aimed at exploring, discovering, analyzing and synthetizing approaches related to the 10R principles, the CE principles and CE business models in the shipping sector in Finland. The research approach was based on qualitative research that aimed at identifying approaches related to the selected three main elements: (1) the 10R principles; (2) the CE principles; and (3) CE business models. The findings of this study suggest that most approaches that were identified were related to the following 10R principles: (1) replacement of products or making of products redundant (R0); (2) rethinking of products (R1); and (3) reduction in the use of resources in the manufacturing and use of products (R2). Only a few approaches could be identified that were related to the reuse of products (R3), the recycling of materials (R8) and recovery of materials (R9). There were typically no or only a few approaches identified that were related to the repair of products (R4), refurbishment of products (R5), remanufacturing of products (R6) and repurposing of products and their parts (R7). For many companies, there were no identified approaches related to the R3–R7 principles. Regarding the CE principles, the findings of this study suggest that quite a number of approaches were identified that were related to the circulation of products and materials and that many approaches were identified that were related to the elimination of waste and pollution. Typically only a few approaches were identified for the regeneration of nature. Regarding the CE business models, the findings suggest that quite a number of approaches were identified that were related to the circular supply models, supply chains and inputs, and there were many approaches for resource recovery. Only a few approaches were identified that were related to product use/life extension, sharing and sharing platforms, and product-as-a-service and product-service systems. Full article

Rising raw material costs and complex global supply chains have reduced the durability and availability of conveyor belts. In response, condition-based maintenance (CBM) with in situ diagnostics has become essential. This case study from a Polish lignite mine shows how subjective visual inspections were replaced with objective, repeatable measurements of belt core condition and thickness. Shifting refurbishment decisions from the plant to the conveyor improved success rates from 70% to over 90% and optimized belt lifecycle management. Sensor-based monitoring enables predictive maintenance, reduces premature or delayed replacements, increases belt reuse, lowers costs, and supports the circular economy by extending belt core life and reducing raw material demand. The study demonstrates how real-time, sensor-based diagnostics using inductive and ultrasonic technologies supports predictive maintenance of conveyor belts, improving refurbishment efficiency and lifecycle management. Full article

In recent decades, Japan has faced rural depopulation due to urban migration, resulting in widespread property abandonment, the “Akiyas”. This paper presents RE-HAK (Refurbish to Host in Akiyas), a blockchain-based framework promoting a circular economy (CE). RE-HAK enables occupants to live rent-free in Akiyas by completing AI-managed refurbishment milestones via smart contracts. Each milestone—waste removal, structural repairs, or energy upgrades—is verified and recorded on the blockchain. Benefits include: (1) rural economic revival through restoration incentives; (2) sustainable CE adoption; (3) preserving property values by halting deterioration; (4) safeguarding cultural heritage via traditional architecture restoration; and (5) transparent management through automated contracts, minimizing disputes. Findings from three case studies demonstrate RE-HAK’s adaptability across skill levels and project scales, though limitations such as rural digital literacy gaps and reliance on government support for scalability are noted. The framework advances Japan’s revitalization goals while offering a replicable model for nations facing depopulation and property abandonment, contingent on addressing technological and policy barriers. Full article

The European building sector significantly contributes to the EU’s greenhouse gas reduction goals, with the 2024 Energy Performance of Buildings Directive (EPBD) aiming to achieve a decarbonised building stock by 2050. By focusing on an existing office building representative of the Italian building stock, this research evaluates various energy efficiency measures and integrates renewable energy systems to transform the building into a Zero-emission Building (ZeB). Moreover, it also utilises future weather data to address the effects of climate change. Results highlight the actions needed for an empirical ZeB transition, offering insights into challenges and key performance indicators across different intervention scenarios. The findings contribute to establishing national ZeB standards, emphasising the importance of the national building renovation plan in compliance with the EPBD recast requirements. Full article

Durable plastics are a sustainability challenge for healthcare products. Orthopedic products are regulated with strict specifications for human tissue interactions. Healthcare engineers and managers select plastic to meet the full range of material properties. Plastic is plentiful, low cost, and reliable, with established supply chains. Used plastic products can be discarded using existing waste management systems with low externality costs for orthopedic businesses. However, plastic is produced from fossil petroleum, raising issues for sustainability commitments of healthcare product companies. Barriers to the transition away from single-use plastic toward circular systems and bio-based healthcare products have been studied, but the transition is a goal that has yet to be realized. This research article reports on a transition engineering design sprint with a medium-sized orthopedic company specializing in orthoses for children and teenagers. The design sprint process engages company experts with systems perspectives on the role of unsustainable plastic in orthopedic healthcare and illuminates opportunities for capturing value in business transition. Two system transition project concepts were co-developed. The first concept is a plastics value map that aims to converge the satisfaction of essential needs with the usefulness of plastics under the limitations of a biophysically constrained future economy. The second concept is an orthopedics library data system concept that would allow reusing of fit-for-purpose used products and to inform the refurbishment of used products. In addition to an explanation of the design of the two concepts, the article presents reflections of co-design stakeholders on the usefulness and usability of the concepts. The article provides a real-world application of the co-design processes in transition engineering and the reflection by the company on the value of the results. The results indicate that the co-designed concepts could enable the company to address its sustainability aspirations and potentially resolve the dissonance of sustainability and business viability. Full article

The renovation of buildings impacts various factors; one of them is the economic aspect, which has a significant influence on the decision-making process in building refurbishment, especially in social housing. An often-neglected aspect of renovation is the influence of climate change. Typically, historical climate data are used to estimate the building’s future energy needs. However, due to climate change, this approach may fail to accurately represent future environmental conditions, resulting in miscalculations in energy consumption and costs. This study analyzed a building archetype obtained from the TABULA webtool with the characteristics of a social house building located in Trieste. Dynamic simulations were performed using DesignBuilder and EnergyPlus software and future climate models (the GERICS_CNRM-CM5 and GERICS_IPSL-CM5A-MR models obtained from the EURO-CORDEX database). The projected energy needs of the renovated building and its economic effects were compared with current scenarios, and due to the uncertainties in economic parameters, the outcome is expressed in terms of percentiles of the Net Present Value (NPV). The results of this study show that since temperature increases in the future, the need for energy in the heating period reduces, while the need for cooling increases, directly affecting the statistical distribution of the NPV. Full article

The refurbishment of school buildings offers the opportunity to reduce energy consumption and carbon emissions, which positively influences reductions in environmental impact. It is also important to remember to maintain or enhance the comfort of the users of such buildings. This paper presents a systematic review of the state of the art of current trends and low-carbon technical, operational, and behavioural methods used in the refurbishment of school buildings in cool temperate climates. This subject matter is positioned at the interface of architecture and environmental engineering. This study identifies the most commonly used active and passive refurbishment methods, as well as the research gaps and problems of applied solutions, and demonstrates the most likely and cost-effective optimisation directions in existing schools. The article also considers the issue of innovative technologies, the increasing impact of climate change, and the impact of less predictable phenomena, such as the outbreak of the COVID-19 pandemic and its huge impact on school buildings. Full article

The cyclic process of the circular supply chain (CSC) involves many stakeholders, and how to synergistically promote the active participation of different entities in CSC practices in the complex context of interacting factors is an important condition for moving towards low-carbon sustainable development and realizing the economic benefits as well as the competitive advantages of enterprises. Therefore, based on the technology cycle perspective (recycling, remanufacturing, refurbishing, repairing, and reusing), this study combines text mining and bibliometrics to identify CSC drivers, establish a factor prioritization assessment model, and construct a comprehensive framework for a set of CSC implementation pathways covering multiple subjects and multidimensional factor interaction mechanisms. The results emphasize that the most critical drivers are policies and regulations, resource use efficiency, and consumer awareness and attitudes, with contribution rates of 5.1%, 4.5%, and 4.5%, respectively. On this basis, this paper explores the efficiency-enhancing path strategy for the synergistic implementation of CSC by multiple subjects from the perspectives of the four key subjects of CSC. It puts forward policy recommendations to promote the successful implementation of CSC at the level of mechanism construction and specific operation, to provide theoretical guidance for the cooperation of upstream and downstream subjects. Full article

Cables are critical to the safe and reliable operation of nuclear power plants (NPPs) since they are widely used as a connection medium for various safety-critical equipment. According to research data and operational experience (OPEX), cable materials can degrade with time, resulting in reduced dielectric strength and higher leakage current. Cables may degrade gradually over time under normal service conditions and fail unexpectedly as a result of sudden exposure to harsher environments, such as Secondary Steam Line Breaks (SSLBs), or when required to operate under the severe conditions of a design basis event, such as a Loss-of-Coolant Accident (LOCA). To assess the condition of medium- and low-voltage cables in Canadian nuclear power plants, numerous inspection methods and electrical testing techniques are employed. These techniques include dielectric spectroscopy, polarization/depolarization current analysis, reflectometry, dielectric standby tests, AC partial discharge, and very-low-frequency (VLF) Tan Delta assessments for medium-voltage (MV) cables. While these methods provide precise diagnostic insights, they require cables to be disconnected at both ends and de-energized, posing operational constraints. Consequently, on-line plant cable monitoring has garnered significant interest, particularly for new reactor developments and large-scale NPP refurbishments. This paper provides a comprehensive benchmarking of existing technologies and a state-of-the-art review of modern cable assessment methodologies. It examines commercially available solutions and ongoing research in power testing for low-voltage (LV) and MV cables, with a particular focus on their applicability in nuclear power settings. Full article

In the case of load increases and the refurbishment of existing buildings, it is often necessary to carry out strengthening measures on existing timber beams. When timber concrete composite (TCC) ceilings cannot be used, it is possible to reinforce the undersides of the beams with structural steel or fiber composites (aramid or carbon-fiber-reinforced polymer). This work investigates how significant effects on the load-bearing and deformation behavior can be achieved with these materials in terms of construction practice. The article is intended to show structural engineers which reinforcement measures lead to which forces, deformations, etc., and how these are utilized. This should form the basis for the planning of reinforcement measures, as it is not clear from the beginning whether AFRP, CFRP, or steel is the most suitable material. For this purpose, a comparative parameter study was carried out under practical conditions and with a variable degree of reinforcement using the corresponding formulas. The internal forces in the timber and reinforcement cross-sections, the deflection behavior, and the failure loads at the strength and design levels were calculated. It was demonstrated that, particularly for steel and carbon-fiber-reinforced polymer (CFRP) reinforcements, significant increases in the ultimate load can be achieved and the often-important deformation behavior can be significantly improved. Especially the steel variant leads to high improvements in deflection and breaking load behavior, with the base material (wood) also being utilized more economically as a result. A comparative ecological study in the form of the global warming potential showed that reinforcement methods are also advantageous from the point of view of sustainability compared to renovations with timber concrete composite slabs or new concrete slabs. Full article