Search Results (1,133)

Upon the challenges of climate change and the demand for energy sustainability, nuclear power (NP) units not only provide clean electricity but are also equipped for cogeneration to achieve energy cascade utilization; this represents a key avenue for improving the overall efficiency and achieving the comprehensive utilization of nuclear energy. However, following the heating retrofitting stage, there exists a risk that the supply control valve of the unit may accidentally open completely during operation, which increases the risk of over-powering. Therefore, this study designs response schemes for second-generation large pressurized water reactor NP plants (NPPs) under the accidental full-open condition of the heat-supply control valve. Specifically, an integrated model encompassing the nuclear steam supply system, secondary circuit system, thermal energy supply system (TESS), and related control systems was constructed using the optimal estimation program and 3KeyMaster simulation platform. Subsequently, two response schemes were designed for the accidental full-open valve scenario under two operation modes—namely, the “Reactor Follows Turbine + TESS” and “Turbine Follows TESS” modes. Finally, on the basis of the established simulation platform, the scenario of accidental full opening of the heat-supply control valve was simulated and verified. Ultimately, the results indicate that the response scheme implemented under the “Turbine Follows TESS” mode is more effective in suppressing nuclear overpower when the heat supply control valve accidentally opens fully. Thus, overall, this study provides a feasible accident response strategy and critical technical reference for NPPs involving cogeneration and energy cascade utilization. Full article

With the wave of new campus construction gradually receding, the focus of green campus planning and design is shifting toward the low-carbon retrofitting of the existing built environment. University campuses often face challenges such as dispersed land use, inadequate spatial planning, disorganized road layouts, suboptimal landscape design, and low energy efficiency. Grounded in a review of current research on campus carbon emissions, this study integrates green technology indicators with planning and design approaches to establish a multi-scale, context-adaptive planning framework for carbon control, spanning five dimensions: intensive land use, spatial layout, transportation systems, landscape development, and facility integration. Employing a combined approach of bibliometric analysis and case studies, this research examines and compares typical university campuses both domestically and internationally to validate the effectiveness of the synergistic “technology-system-behavior” pathway in mitigating high-carbon lock-in. Through a systematic comparative analysis of representative low-carbon campuses, the synthesized results indicate that under optimal operational conditions, the clustered reorganization of functional zones demonstrates the potential to reduce transportation carbon emissions by approximately 25%; comprehensive retrofitting of building envelopes can decrease building energy consumption intensity by an estimated 30%; a multimodal coordinated transport system can increase the share of non-motorized travel to around 65%; establishing high carbon-sequestration plant communities can enhance carbon sink capacity by up to 30%; and smart facility integration can reduce overall campus carbon emissions by a projected range of 25–40%. It should be noted that these quantitative outcomes represent high-probability potential ranges, with actual performance subject to behavioral and operational fluctuations. This study provides theoretical support and practical pathways for achieving “near-zero carbon campuses” and underscores the important demonstrative role that higher education institutions can play in addressing climate change. Full article

Urban underground infrastructures are highly vulnerable to intense rainfall events, particularly access stairs, where preferential runoff paths and the most probable evacuation routes can conflict. This study presents a pluvial flood hazard assessment for underground access stairs in the Barcelona Metropolitan Area Metro network. It integrates the EU ICARIA project modeling framework and the hazard assessment criteria based on hydraulic parameters identified by the Spanish national research project FAVOUR. Both current and future climate change rainfall scenarios are considered. The results showed that out of 415 underground access points, 27 face a high risk of floods, while 35 more have potentially high-risk conditions. These figures could rise to 38 (40% increase) and 47 (74% increase) respectively by the end of the century since climate change is projected to increase rainfall intensity and frequency. By quantifying hazard levels across the network, this study allows the identification of points of the infrastructure where hazard conditions can be more critical. Furthermore, the results presented could potentially support targeted adaptation strategies such as entrance retrofitting, improved drainage design, and emergency planning to develop resilient and sustainable cities. The proposed methodology demonstrates how ICARIA’s modeling framework can effectively evaluate and anticipate flood hazards in complex urban environments at the asset level. Full article

Indoor air quality (IAQ) in educational buildings plays a critical role in the health, cognitive performance, and well-being of occupants. Aging university facilities often rely on outdated ventilation systems that are not designed to meet current demands or respond to dynamic occupancy levels. This study investigates the performance and feasibility of various advanced ventilation strategies in comparison to an existing balanced mechanical ventilation (BMV) system in a university classroom accommodating 100 students. Using a Dynamic Building Energy Simulation Program, simulations were conducted to evaluate IAQ (using CO₂ levels), energy consumption, and thermal comfort under three retrofitting scenarios: BMV, demand-controlled ventilation (DCV), and hybrid ventilation combining natural and mechanical airflow. The simulations indicate that DCV cuts annual HVAC energy use by 33% relative to the baseline, while the hybrid strategy achieves the greatest reduction of 42% and maintains CO₂ levels and thermal comfort within recommended limits. Although hybrid systems provide seasonal advantages, their complexity may limit applicability. In addition to technical analysis, this study also explores the financial and tax-related challenges associated with retrofitting ventilation systems in university buildings. Investment payback periods, operational costs, and potential tax incentives are discussed to evaluate economic viability. Overall, the endorse hybrid ventilation as the most cost-effective strategy where mixed-mode control is feasible, and DCV as a practical alternative for buildings unable to employ natural ventilation. Full article

This paper presents a design research study that develops a comprehensive conceptual framework for an integrated digital twin system for architectural heritage. The framework aims to explore mechanisms for real-time monitoring and the coupled regulation of structural health, microclimatic conditions, and energy performance. In the context of the ongoing global warming emergency, this framework supports climate adaptation strategies for heritage sites. It enables a fully coordinated operational process encompassing real-time sensing, predictive analysis, coupled control, and decision support. In the structural dimension, the framework is designed to utilise sensors to monitor and warn against cracks, settlement, and deformation, whilst integrating models to analyse stress conditions. In the microclimate dimension, the study envisages predicting and adjusting HVAC and lighting systems based on environmental parameters and footfall monitoring data via algorithms, with the aim of balancing occupant comfort with humidity control and mould prevention. Regarding energy, the framework optimises equipment operation through smart metering and algorithms and we propose a modelling tool for the quantitative assessment of energy-saving retrofit effects. Furthermore, the framework incorporates the establishment of an open-access dataset covering structural, microclimate, and energy use data, providing data standards and a foundation for subsequent empirical research. Full article

The evaluation of the seismic behavior of masonry aggregates, which characterize Italian historic centres, is a challenging and widely debated topic in the field of structural engineering. These constructions, composed of several adjacent structural units, tend to exhibit both global and local damage when subjected to horizontal seismic actions—loads that were not considered at the time of their original construction. Developed over centuries of unplanned urban growth, they are based on empirical construction rules and locally sourced materials. Due to their poor thermal properties, these buildings are also affected by significant heat losses, resulting in reduced indoor comfort. In this context, the present study aims to evaluate the seismic performance of a masonry aggregate and two of its constituent structural units located in Visso, in the province of Macerata, an area severely affected by the 2016 Central Italy seismic sequence, both before and after the application of an innovative integrated retrofitting solution. The proposed strengthening system combines aluminium alloy exoskeleton with insulating sandwich panels, simultaneously addressing seismic vulnerability and energy inefficiency. The assessment is carried out through numerical analyses, including nonlinear static and dynamic approaches, to achieve a comprehensive understanding of the structural response. Moreover, a comparative analysis between the masonry aggregate and the two individual structural units, modelled as isolated buildings, is performed to investigate the influence of structural interaction among adjacent units. The results demonstrate the effectiveness of the proposed retrofitting strategy, highlighting a significant improvement in global stability. Furthermore, the comparison confirms the critical role of inter-unit interaction and underscores the necessity of modelling historic masonry aggregates rather than isolated buildings to obtain a more realistic seismic performance evaluation. Full article

Phosphorus is a ubiquitous contaminant in urban and agricultural landscapes. A retention basin located in the southern part of Barnegat Bay, New Jersey, was identified as receiving stormwater runoff with elevated phosphorus concentrations. The basin is surrounded by expanding urban development, contributing to the progressive degradation of water quality in the bay, which is already highly eutrophic. This study evaluated the effectiveness of a culvert retrofit with a green filter media composed of granulated-aluminum-based drinking water-treatment residuals (Al-WTR) and granular carbon (5:1 ratio, w/w) for the removal of phosphorus and suspended sediments from stormwater runoff. The performance of the filter media was assessed through water quality monitoring following runoff events over a 12-month period. The results indicated that the green filter media achieved up to 52% removal of total phosphorus from stormwater influent. However, treatment efficiency declined after approximately five months due to clogging of the geotextile bag housing the media. The replacement of the geotextile bag restored phosphorus removal performance (59%), highlighting the importance of routine maintenance. The findings demonstrate a cost-effective, environmentally sustainable, and innovative green engineering approach for mitigating phosphorus contamination in urban stormwater. Full article

The high energy consumption in the building sector and the increasing impacts of climate change have necessitated the transition to net-zero-energy buildings (NZEBs), in which energy retrofit strategies play a key role. However, neglecting moisture transport and climatic design while improving energy efficiency often leads to reduced building performance, material deterioration, worse occupant health, and indoor environmental problems. This review examines in detail the basic mechanisms of moisture transport, including diffusion, capillary action, and airborne moisture transport, and illustrates how poor moisture control affects thermal performance and resident health. Additionally, a comparative analysis of the impact of retrofit strategies implemented in different climatic regions on energy efficiency, carbon emission reduction, moisture-related failures and net-zero goals is conducted. At the same time, the need exists to incorporate awareness regarding the adverse effects on the health of occupants. This systematic review analyzed 120 peer-reviewed studies published from 1994 to 2026, covering different climatic regions (e.g., cold, temperate, warm–humid, etc.). The analysis found that the energy savings rates were reported to range from 18% to 45%, while the moisture-related failures in inappropriately retrofitted buildings were observed to increase by up to 32% in some cold regions. This research review provides a comprehensive advisory framework for domestic residents to take remedial steps until retrofit experts gain access in order to prevent health risks from mold and moisture ingress, which can contribute to a healthy lifestyle and a net-zero-energy building. Full article

Open-air asphalt milling generates hazardous respirable crystalline silica (RCS), posing severe risks to operators of legacy machines lacking enclosed cabs. This study evaluates a novel, standalone retrofit water spray system designed to intercept fugitive dust. Field validation across 11 road maintenance sites involved particle characterization and paired system-off/on exposure monitoring. Results indicated a Mass Median Aerodynamic Diameter (MMAD) of 6.12 µm, confirming the efficacy of fine-atomizing nozzles (0.3 mm) for capturing respirable fractions. The system achieved RCS suppression efficiencies ranging from 60% to over 85% under low-to-moderate wind conditions (<2.5 m/s). A comparative analysis revealed no significant performance gain from larger 0.5 mm nozzles, supporting the use of smaller orifices for optimal water conservation. However, suppression efficacy degraded significantly when crosswinds exceeded 2.5 m/s, indicating a potential operational boundary. This retrofit solution provides a scientifically validated, cost-effective engineering control for reducing occupational silica exposure in aging road maintenance fleets. Full article

Distributed passive vibration control systems (VCSs) offer an attractive solution for improving the seismic response of multi-story buildings, particularly in seismic retrofit applications and when soil–structure interaction (SSI) effects are explicitly considered. This study presents a soil-dependent optimization framework of distributed Tuned Mass Damper (TMD) and Tuned Mass Damper Inerter (TMDI) systems applied to a ten-story building. The proposed framework determines the optimal number, tuning, damping and spatial distribution of these VCS, including non-collocated inerter configurations for TMDI layouts, while also examining different auxiliary mass ratios. Soil–structure interaction effects are explicitly incorporated by considering four soil classes (A–D) in accordance with Eurocode 8, enabling a systematic evaluation of soil-dependent vibration control effectiveness. Structural performance is evaluated using normalized performance criteria associated with peak absolute floor displacements, floor accelerations and inter-story drifts. The results indicate that distributing control devices along the height of the structure enhances seismic mitigation for both TMD and TMDI configurations, with performance improvements becoming more pronounced as the number of devices increases. Moreover, TMDI systems consistently achieve superior response reduction compared to TMDs across all soil classes, highlighting their potential as a robust, efficient, and lightweight passive vibration control solution for seismic retrofit applications involving SSI effects. Full article

Cultural heritage buildings constitute an irreplaceable record of historical, social, and architectural identity, and their preservation is essential for cultural continuity and sustainable development. However, their conservation is inherently challenging due to material aging, complex construction techniques, limited documentation, and strict intervention constraints that restrict invasive monitoring or retrofitting solutions. Environmental degradation and microclimatic effects further accelerate deterioration, often in ways that are difficult to quantify or predict. This paper presents RADAR, a non-invasive, data-driven framework for assessing environmental and structural risk in cultural heritage buildings. The proposed approach integrates high-resolution geometric acquisition, computational fluid dynamics (CFD) modeling, and environmental monitoring to analyze airflow patterns, temperature distribution, and moisture-related decay mechanisms. By combining measured data with numerical simulations, RADAR enables the identification of high-risk zones and deterioration drivers without altering the building fabric. The framework is demonstrated through a real-world case study, illustrating its applicability as a decision-support tool for preventive conservation and heritage management. Full article

The decarbonization of the building stock by 2050, as set by the European Green Deal, calls for an unprecedented wave of energy renovations. Yet, reliable evidence on the real costs and performance of retrofit interventions remains scarce. This paper presents the results of a large-scale technical and economic analysis conducted on 34 residential buildings, all renovated under a national Italian programme supporting energy efficiency improvements. For each building, pre- and post-renovation energy performances were assessed using standardised procedures, while detailed investment cost data were collected for all implemented measures, including envelope insulation, HVAC system upgrades, and renewable integrations. By combining these datasets, the study evaluates the actual cost-effectiveness of different retrofit strategies, revealing the true financial effort required to achieve substantial energy improvements. The results highlight both the opportunities and limitations of current approaches, showing a significant gap between theoretical models and real outcomes. The findings contribute to the European debate on the economic sustainability of deep renovation policies. Full article

Steel jackets are widely used for the seismic retrofitting of reinforced concrete (RC) beam–column joints. However, the details and efficiencies of steel jackets are directly impacted by the presence of transverse beams. An in-depth understanding of this issue has been lacking so far. In this study, using realistic configurations of transverse beams, the seismic performance of exterior RC beam–column joints retrofitted according to the modified steel jacketing method were investigated numerically and theoretically. The refined nonlinear three-dimensional finite element approach was adopted and verified against experimental observations. A series of parameters were considered, including the number of transverse beams; the thickness, width and spacing of the steel strips at joint panels; and the axial compression ratio of columns. The results obtained from twenty specimens in terms of load response, cracking pattern, stress distribution, stiffness degradation and energy dissipation confirmed the effectiveness of the modified steel jacketing method. Significant differences among the roles of the parameters were revealed, and the reasons behind the differences were analyzed. Moreover, by means of significance analysis, the width and thickness of the steel strips were identified as the most influential parameters on the shear capacities of the joint panels with single- and double-sided transverse beams, respectively. Furthermore, based on the softened strut-and-tie model, a design approach for predicting the shear contribution of steel jackets in the presence of transverse beams was proposed for engineering applications. Full article

A gyroscopic stabilizer generates an anti-roll moment by regulating the precession angle of a high-speed rotor. By computing the precession-angle command in real time, the controller can effectively suppress roll motion. However, research on the application of gyroscopic stabilizers to floating wind turbines remains limited. In this study, the operating mechanism of a gyroscopic stabilizer is modeled, and frequency-domain stability analyses are conducted for the system dynamics both before and after the installation of the stabilizer. A pole-placement-based controller is designed to achieve active stabilization of wave-induced platform motions by adjusting the rotor precession angle. Based on wave spectrum analysis, numerical simulations are performed to compare system responses with and without the active controller under different sea conditions. The results demonstrate that the proposed anti-roll control strategy exhibits robust performance and can increase the roll reduction rate by at least a factor of two across a range of sea states. In addition, the anti-roll effectiveness is influenced by rotor speed and environmental conditions, with higher reduction rates achieved at higher rotor speeds, larger wave heights, and longer wave periods. In addition, we adopt a dual-gyro configuration to cancel yaw-interference moments, and the proposed controller is feedback-based (platform motion only), which is suitable for retrofit applications without requiring wave-preview sensors. Full article

Iron-based shape memory alloys (Fe-SMAs) are promising for structural retrofitting because of their low cost, corrosion resistance, and manufacturability. However, the effect of strain rate on the coupled thermo-microstructural evolution during cyclic training remains underexplored. In this study, samples underwent cyclic tensile training at quasi-static and impact strain rates. After each cycle, DSC was adopted to obtain transformation temperatures and enthalpies, and selected cycles were characterized by EBSD (KAM and IPF) to quantify phase fractions and variant statistics. Results show tensile loading shifts transformation temperatures, with the principal difference between regimes appearing in the evolution of martensite finish temperature. Under impact loading, the transformation enthalpy increases more rapidly (0.18 to 0.8 J/g in absolute value), and the driving force decreases more markedly by the fourth cycle (−0.0578 to −0.1117 J/g), indicating faster thermodynamic changes at high strain rates. Internal stress and dislocation storage accumulate faster under impact, lowering the effective stress (−17.01 MPa) for transformation and promoting martensite nucleation/growth. EBSD reveals increasing lattice distortion; in impact-trained samples, single-variant martensite and higher stored energy reduce interface resistance and enable elastic energy release, accelerating transformation and improving shape recovery. Full article