Search Results (4,865)

Carbon fiber-reinforced thermoplastic composites (CFRTPs) have attracted increasing attention in aerospace, transportation, marine engineering, and other advanced manufacturing fields owing to their high specific mechanical properties, impact resistance, weldability, reprocessibility, and potential recyclability. However, the high melt viscosity of thermoplastic matrices, the permeability limitations associated with different reinforcement architectures, and the chemical inertness of carbon fiber surfaces continue to restrict resin impregnation, interfacial bonding, defect control, and forming stability. This review systematically summarizes recent advances in CFRTP manufacturing from the perspective of material-derived processing challenges and interface engineering. First, representative thermoplastic matrix systems and reinforcement architectures are discussed, with emphasis on their effects on processability, crystallization behavior, resin flow, and load transfer. Subsequently, six major forming processes, including hot stamping, injection molding, pultrusion, filament winding, automated fiber placement, and additive manufacturing, are critically compared in terms of processing principles, typical defects, technical limitations, and application boundaries. Particular attention is given to process-induced quality issues such as voids, wrinkling, springback, fiber breakage, warpage, insufficient consolidation, and weak interlayer bonding. Finally, interface engineering strategies, including chemical surface modification, interfacial structural design, and functional interlayer design, are reviewed as practical routes to improve wetting, shorten impregnation pathways, and enhance fiber–matrix load transfer in high-viscosity thermoplastic systems. This review highlights that CFRTP manufacturing should be understood as a coupled materials–processing–interface problem rather than a single forming operation. Future development is discussed with emphasis on reproducible manufacturing, processability-oriented materials, scalable interface engineering, predictive modeling, and standardized structural validation. Full article

The insulated gate bipolar transistor (IGBT) is widely applied in industrial fields such as rail transit, wind power generation, smart grids, and renewable energy. The temperature distribution, stress variation patterns, thermal performance, and modeling damage in the solder layer of IGBT modules under thermal and stress loadings have rarely been studied. This study first established a three-dimensional geometric model based on the actual dimensions of the IGBT module. A finite element model was successfully constructed for thermal/mechanical multi-physics coupled simulation based on the ANSYS Workbench platform to simulate the temperature, deformation trends, and stress distribution patterns of the solder layer in the IGBT module. Secondly, the solder layer defects of the IGBT module were categorized into five major types, and 37 sets of 3D models of IGBT with damaged solder layers were designed, followed by thermal/mechanical coupled simulation analysis for each. Finally, the influence of the void positions, sizes, and distribution types in the solder layer on the module temperature, heat dissipation path, and thermal stress was simulated during thermal cycling. The results showed that the highest stress at the edge of the solder layer is 6.2504 × 10⁷ Pa, the lowest junction temperature is 70.79 °C, and the average thermal stress is 1.2388 (m/m). The highest junction temperature reached 72.562 °C under central solder layer damage states as determined by a thermal/mechanical coupled simulation analysis of four different types of solder layer defects. This research provides a theoretical basis and reliable technical support for the anti-damage and failure of IGBT modules and high-power devices. Full article

The tuned mass damper (TMD) exhibits good performance in suppressing wind-induced vibrations of high-rise structures. However, a single TMD has a limited control bandwidth and poor robustness. The multiple-pendulum tuned mass damper (MPTMD) offers advantages, such as a wider control bandwidth, stronger robustness, and a simple structural configuration, while its working frequency can be easily adjusted by varying the pendulum lengths. With two optimization objectives, namely displacement and acceleration, this study derives the displacement and acceleration dynamic amplification factors of the primary structure equipped with the MPTMD under external excitation and examines the interrelationships among the optimal parameters and their underlying mechanisms. The accuracy of the proposed optimization method and the effectiveness of the MPTMD are validated by fitting the theoretically derived optimal parameter curves with results from numerical simulations. Finally, the control performance of MPTMD and TMD is compared through a numerical example subjected to realistic wind load excitations, verifying the control effectiveness of MPTMD. Nevertheless, several limitations should be acknowledged. The present optimization is based on a single-degree-of-freedom (SDOF) primary structure and targets only the first translational mode; the effects of higher modes and multi-degree-of-freedom (MDOF) coupling are not considered. Additionally, the wind load is represented by a synthetic time history with a fixed return period, and uncertainties in real wind fields are not fully addressed. Future work should extend the proposed method to multi-modal control, nonlinear behavior, and experimental validation. Full article

Offshore floating photovoltaics (OFPVs) offer a promising route for expanding solar energy development from land and inland waters to marine space, particularly in China’s coastal regions where electricity demand, land-use constraints, offshore wind infrastructure, and photovoltaic manufacturing capacity are highly concentrated. This review examines the development status, structural concepts, hydrodynamic challenges, research methodologies, reliability issues, and future pathways of OFPV systems in China from the perspective of marine engineering. Demonstration projects, representative platform concepts, and recent studies on environmental loading, platform motion, multi-body interaction, connector and mooring responses, and hydroelastic behavior are systematically synthesized. The review shows that Chinese OFPV technology has progressed from conceptual exploration to prototype testing and sea-based validation, with flexible membrane, steel-frame, semi-submersible, tensioned floating-island, HDPE modular, and composite-material concepts under active investigation. However, mature and replicable engineering solutions remain limited. Key barriers include survivability under extreme sea states, fatigue reliability of large arrays, corrosion, biofouling, material degradation, insufficient long-term field data, and the lack of dedicated design standards. Future development should emphasize array-level hydrodynamic design, coupled connector–mooring optimization, life-cycle reliability assessment, full-scale monitoring, and integration with offshore wind, wave energy, floating breakwaters, aquaculture, and other marine energy systems. Full article

Individual differences in outdoor thermal comfort (OTC) are critical to the healthy use of urban public spaces, yet whether thermal preference can shape OTC independently of demographic characteristics remains largely unexamined. Using residential outdoor spaces in Fuzhou, a representative hot-humid city in China, as a case, this study combines field measurements and questionnaire data from 296 respondents (72.6% aged 60 or above) with explainable machine learning and K-Modes clustering to examine how thermal preference drives individual differences in OTC. Three stable preference profiles were identified—heat-sensitive (56.4%), wind-seeking (20.3%), and heat-tolerant (23.3%)—which exhibit markedly different thermal responses. The neutral globe temperature ranges from 29.90 °C for the heat-sensitive profile to 35.85 °C for the heat-tolerant profile, a difference of 5.95 °C, whereas the comfort bandwidth is widest for the heat-sensitive profile (9.03 °C) and narrowest for the heat-tolerant profile (4.13 °C), the former being 2.2 times the latter. The profiles are independent of sex and BMI and only weakly correlated with age, yet their explanatory power for the variance in thermal comfort vote (TCV) (η² = 0.254) is 4.9 to 23.1 times that of the demographic variables. The thermal environment contributes far more to TCV than the visual environment (74.4% versus 25.6%), with globe temperature (Tg) as the strongest single factor. Overall, differentiated design that adopts the most heat-sensitive profile as the constraint boundary covers the comfort needs of a broad population more effectively than demographic stratification. The novelty of this study lies in introducing psychologically grounded thermal-preference profiles as an operational stratification dimension for architectural design, offering age-friendly hot-humid residential environments a preference-oriented pathway toward refined, human-centered outdoor space design. Full article

The structural dynamic characteristics of super high-rise buildings are key to understanding how they respond to wind-induced vibration. Currently, one widely adopted method involves using vibration sensors to capture structural vibration responses through on-site measurements, followed by identifying structural dynamic characteristics using output-only methods. However, when measuring and analyzing the dynamic characteristics of super high-rise buildings, the modal directions associated with the vibration modes of the structure are often ignored, which can lead to identification errors. This is particularly true for super high-rise buildings with irregular cross-sections, for which research into the impact of actual structural vibration modes is notably lacking. Therefore, this study uses a normal mode decomposition method to examine the determination of structural vibration mode directions in detail. This method identifies the angular deviation between the viewing and normal coordinates by analysing the spectral energy distribution. It then decomposes the measured signal in the viewing coordinate system based on this deflection angle. This achieves decoupling of modes that are coupled in both directions. Specifically, the study analyses the phenomenon of modal aliasing in structural modal parameters from both time-domain and frequency-domain perspectives based on the measured acceleration response signals of a super high-rise building with a non-circular cross-section during Super Typhoon Saola, and employs the structural modal orthogonal decomposition method to determine the modal directions. The fundamental sway modes of the structure exhibit aliasing between the two adjacent modes at 0.1748 Hz and 0.1825 Hz due to a 46° angle of deviation between the viewing and normal coordinates. Based on the clarification of modal directions, the study further refines the identification of structural modal parameters. Following decoupling, the dispersion of the damping ratio and frequency identification results in the normal coordinate system decreased significantly (concentrating at 1.0–2.0% and 0.175–0.185 Hz, respectively). The damping ratio increased by 1.0% with increasing amplitude, while the frequency decreased by 0.005 Hz with increasing amplitude. The research findings help to improve the accuracy with which the dynamic characteristics of super high-rise buildings can be identified, thereby enabling the structure’s wind-induced response to be assessed more rationally. Full article

We propose a decentralized strategy for coordinating the bidirectional charging and discharging of battery electric vehicles (BEVs) in renewable-powered parking lots. The framework combines mean-field games (MFGs) and model predictive control (MPC) to address the coupled stochastic dynamics induced by uncertain renewable generation and random vehicle arrivals and departures. Solar and wind power fluctuations are modeled using autoregressive moving-average (ARMA) processes, while the time-varying vehicle population is represented through finite Poisson processes. The coordination problem is formulated as a large-scale game, where an aggregator designs individual cost functions to maximize available energy utilization while promoting fairness through near-equal states of charge (SOCs) at departure. Scalability is achieved through MFG theory, ensuring convergence and stability even under highly volatile generation and fluctuating agent populations. Numerical simulations validate the proposed strategy against two straightforward algorithms: capacity-ordered saturation allocation (COSA) and capacity-ordered fair allocation (COFA). These centralized approaches achieve high target fulfillment in static, low-intensity environments, where available energy accommodates a stable fleet without exceeding power limits. However, their efficacy degrades significantly in dynamic, high-intensity environments, where the interplay of volatile generation, continuous fleet turnover, and strict power constraints strains the system. In contrast, the proposed MFG-MPC framework provides a decentralized response that elegantly navigates the trade-offs between energy availability, demand stochasticity, and power limits. Ultimately, this approach ensures robust energy utilization while safeguarding vehicle equity, confirming its strong suitability for real-time deployment. Full article

Winter underuse of urban parks in severe-cold cities limits year-round outdoor activity, especially for cold-sensitive users. This study developed a comfort–risk–adaptation framework integrating thermal perception, model-estimated cold-stress risk, and behavioral responses. Field microclimate measurements and synchronous questionnaires were conducted in Nanhu Park, Changchun, China, under clear winter conditions, yielding 386 paired human–environment samples. The Universal Thermal Climate Index (UTCI), Required Clothing Insulation (IREQ), wind chill temperature (WCT), and contact cooling indicators were used to quantify thermal exposure and cold-stress risk. Results showed significant spatial differences in wind speed, solar radiation, mean radiant temperature, and UTCI, while air temperature and humidity varied little. The neutral UTCI was 3.14 °C (unweighted) and 3.70 °C (weighted), and the 80% thermal acceptability threshold was −15.24 °C (95% CI: −16.14 to −14.22 °C). Despite acceptable thermal perception, physiological cold-stress risks remained under certain conditions. The findings highlight the need to integrate solar access, wind mitigation, low-conductivity materials, and moderate activity routes to improve winter usability in severe-cold urban parks. Results are condition-specific and reflect observed users under clear to partly cloudy winter daytime conditions rather than universal thresholds. Full article

Given that strong wind poses a potential threat to the safe operation of tower cranes, a finite element analysis model was established using the finite element method. Considering wind load calculation theory, the stress characteristics of tower cranes under different wind levels and lifting loads were simulated and analyzed. Field tests were conducted to verify the corresponding simulation results. The results show that the safety performance of tower cranes is influenced by the interaction of wind level and lifting load, with certain operational conditions posing safety risks at wind level 5. To ensure safety, tower cranes should be operated under wind level 4 or below. Additionally, during non-working periods in strong winds, the jib should be released to avoid locking it, which could lead to structural collisions. The destructive stress is relatively lower when the tower crane stands downwind. Full article

Extreme wind events, particularly tropical cyclones, pose the most severe safety threat to aging lattice steel space-truss structures in coastal regions, including transmission towers, communication and observation towers, and lattice supports of building-integrated wind-energy facilities. Such structures suffer progressive capacity degradation through multiple concurrent mechanisms, yet their actual residual safety margin under extreme wind loading remains poorly quantified. Current assessment practices rely on code-prescribed simplified wind speeds that ignore terrain-induced local amplification, and assume an intact structural condition that neglects in-service deterioration. This paper proposes a Risk-Based Safety Assessment Framework (RBSAF) that addresses both deficiencies through a five-step pipeline: (i) multi-scale wind field downscaling that resolves terrain-amplified wind profiles at individual structure sites; (ii) independent degradation models for atmospheric corrosion, bolt loosening, fatigue accumulation, and pitting corrosion; (iii) a multi-degradation coupling aggregation method that yields a unified Structural Health Index (SHI) capturing nonlinear interaction effects; (iv) code-based multi-scenario safety margin scanning with automatic identification of weak components; and (v) a risk-informed reinforcement priority mapping strategy. A representative 220 kV angle-steel lattice tower in a coastal mountainous corridor of Southeastern China is employed as the case study. Results show that after 30 years of service in an ISO 9223 C4 corrosive environment, the structure-level SHI decreases from 1.47 (intact, code wind) to 1.00 under the proposed coupled assessment with code-prescribed wind, and further to 0.76 when terrain amplification (15% speed-up) is considered, with the failure probability rising from 3.6% to 24.1%. Multi-degradation coupling causes an additional 28% capacity loss relative to single-factor assessment and substantially alters the weak-component ranking. Reinforcing the five most critical members restores the SHI to 1.25 with only a 2.8% steel-weight increase. The framework provides a systematic, quantitative tool for safety evaluation and maintenance prioritization of aging lattice steel structures in wind-prone built environments. Full article

To address insufficient representativeness and the potential risk of the underestimation of the long-term atmospheric diffusion assessment of nuclear facility gaseous effluents, a CFD numerical simulation framework based on annual joint-frequency weighting of 16 wind directions, 6 wind speed classes and 6 atmospheric stability classes is proposed and applied to a representative multi-source nuclear facility. The regulation law of near-surface flow field of the building complex and the diffusion characteristics of uranium aerosol is analyzed. The results indicate: Complex building matrix facilitates the formation of recirculating wake regions, which may serve as potential zones for aerosol accumulation. The uranium aerosol concentration weighted by joint frequency presents a distribution characteristic of central agglomeration and asymmetric gradient attenuation. Compared with the single most-frequent meteorological scenario, the joint-frequency-weighted field shows a higher expected peak and a 237 m shift in peak position. This shows that the joint-frequency weighting framework can reduce directional bias and underestimation of hotspot extent relative to a most-frequent meteorological condition. The method may provide quantitative support for refined radiation protection management and the environmental monitoring layout of nuclear facilities. Full article

This study investigates the structural sensitivity of a large-span steel space frame at Yanjiao Station to environmental disturbances during the critical “flexible suspension” stage of asymmetric hydraulic lifting. First, by analyzing the offset between the center of mass and the center of stiffness—induced by the asymmetric lifting configuration—the study systematically examines the spatial eccentric amplification effect under a coupled thermal-wind field. To this end, a non-uniform solar radiation model based on the Axis-Aligned Bounding Box (AABB) algorithm is integrated with a refined finite element model, enabling a full-factor parametric analysis under 20 coupled load conditions. The results reveal a significant time lag in the structural temperature field, with 12:00 identified as the critical time for maximum thermal deformation. The wind-induced response follows a “bimodal evolution” pattern, and the maximum translational-torsional coupling effect occurs at wind direction angles of 60° and 120°. Further analysis of the multi-field coupling mechanism indicates that the wind field dominates the deformation mode, while the temperature field amplifies the resulting response. Consequently, the peak displacement reaches 192.50 mm, which represents a 360.81% increase compared to the dead load baseline. The cantilever end is identified as the primary vulnerable region. Based on these findings, a “wind direction–time” two-dimensional monitoring strategy is proposed. This strategy provides scientific quantitative criteria and theoretical support for the construction safety of large-span structures, as well as for the development of a comprehensive early warning and health monitoring system. Full article

Adaptive construction techniques in traditional vernacular dwellings play an important role in improving the wind–thermal microclimate of buildings. However, comparative studies on such techniques across different regions remain limited. Moving beyond a static regional perspective, this study selects six representative skywell dwellings along the historical migration route from Jiangxi to Hunan. Through field monitoring and CFD numerical simulation using PHOENICS, the wind–thermal performance of these dwellings under extreme summer high-temperature conditions is comparatively analyzed. The results reveal case-based regional differences characterized by “shared origins and regional differentiation.” The western Jiangxi dwellings tend to adopt ventilation as the main spatial logic, using open spaces to enhance convective heat dissipation. In contrast, the northern Hunan dwellings show more prominent shading and heat control characteristics, relying on optimized skywell geometry to achieve geometric shading and reduce radiative heat gain. This study clarifies that adaptive construction techniques vary significantly under regional influences, and the findings may provide quantitative data support and design references for optimizing the microenvironment of contemporary buildings. Full article

Understanding turbidity in coastal systems is essential to ensure the sustainable management of these ecosystems, which are increasingly under pressure from natural factors and human activities. Thus, this study aims to develop a local Sentinel-2-based turbidity model for the Aveiro lagoon (Portugal) by combining Sentinel-2 records with in situ measurements. A field campaign synchronized with a Sentinel-2 overpass was conducted across the lagoon channels on 28 May 2025, to capture spatial variability by measuring near-surface turbidity and Secchi depth, for correspondence with the spectral records of satellite. Remote Sensing Reflectance (Rrs) and turbidity were derived using various algorithms integrated within the ACOLITE software (v20250114.0). Additionally, new turbidity models were developed and empirically adjusted based on the Rrs data, with their performance quantified through the coefficient of determination (R²) and Root Mean Square Error (RMSE). The results showed that the existing algorithms are not directly suitable for the Aveiro lagoon, as they underestimate the highest turbidity values. The ratio between 665 and 560 nm bands (RG_ratio) proved to be the most suitable spectral index, performing best in estimating turbidity (R² = 0.822 and RMSE = 1.77 NTU). This study highlights the importance of locally calibrated models over standard ACOLITE algorithms for turbidity retrieval in shallow coastal lagoons, while emphasizing that the proposed model was calibrated for the tidal, wind, and river discharge conditions sampled during the campaign and has not yet been independently validated. Full article

Typhoon-eye sensing places unmanned aerial vehicle (UAV) swarms in a setting where the wind field that carries the target signal also displaces aircraft, drains energy, weakens links, and increases failure risk. A rule that improves only routing or only motion can therefore move the swarm into another failure mode. This paper proposes a risk-driven cross-layer coordination scheme for such missions. A bounded risk index, computed from isolation, connectivity loss, and wind intensity, acts as a supervisory variable for multi-hop reachability maintenance, isolated-node recovery, and layered altitude adaptation. For evaluation, graph reachability is separated from useful data return through a degraded multi-hop aggregation model that includes distance loss, wind-dependent reliability, rain-induced packet loss, relay forwarding loss, and mothership collection capacity. The simulator combines a bounded Holland-type storm field, stochastic turbulence, nonlinear propulsion energy consumption, and wind-dependent structural failure. Against three literature-inspired baselines, two AI-inspired comparators, and six ablation variants, the method keeps a balanced profile across connectivity, isolation, wind exposure, data collection, and survival. In 30-run steady-state robustness tests under heavy-rain attenuation, the full strategy showed clear gains over routing-only and multi-agent reinforcement learning (MARL)-routing comparators in connectivity and isolation, but did not uniformly dominate topology reconstruction or the multi-agent deep deterministic policy gradient–artificial potential field (MADDPG-APF) recovery comparator. The results indicate that, in storm-dominated swarm sensing, resilience comes mainly from coordinating exposure reduction with topology stabilization, rather than from optimizing a single layer. Full article