Search Results (476)

Reliable electricity supply in Colombia’s Non-Interconnected Zones requires sustainable and low-cost energy technologies. Vertical-axis hydrokinetic turbines are promising for this purpose; however, their relatively low power coefficient remains a major challenge. This study combines transient 2D and 3D $k$–$\omega$ SST computational fluid dynamics (CFD) simulations with hydraulic channel experiments to investigate a hybrid Darrieus–Savonius turbine. A 27-case Design of Experiments (DoE) based on 2D CFD was first applied to screen the effects of rotor radius ratio (RR), attachment angle (AA), and water velocity. Within the investigated design space, the configuration with $\mathrm{R}\mathrm{R}=0.5$ and $\mathrm{A}\mathrm{A}=0^{\circ }$ produced the most favorable average performance. The selected configuration was subsequently analyzed using 3D CFD and experimentally evaluated at TSR values of 1.0, 1.1, and 1.2. At TSR = 1.0, the 3D model predicted ${\mathrm{C}}_{\mathrm{P}}=0.1525$, closely matching the experimental value of 0.1541 with a relative error of 1.05%. The results demonstrate that 2D CFD is useful for computationally efficient parameter screening and qualitative trend identification, but it overpredicts absolute performance because it neglects blade tip vortices, spanwise flow, and volumetric wake interactions. Three-dimensional CFD is therefore required for reliable performance prediction and analysis of the complex flow structures governing hybrid hydrokinetic turbine behavior. Full article

Self-start of lift-type Darrieus vertical-axis wind turbines remains one of the main obstacles limiting their wider application, especially at low wind speeds and low Reynolds numbers. This review examines the physical basis of the self-start problem and critically discusses the main aerodynamic and design strategies proposed to improve start-up behaviour. Particular attention is paid to the distinction between the mere initiation of rotation and true self-start, understood as the autonomous acceleration of the rotor from rest to its operating regime. The reviewed approaches include changes in rotor solidity, blade-shape modification, auxiliary blades, slot-based flow control, and active or passive pitch-control systems. The available studies show that increasing solidity generally improves low-TSR torque and facilitates start-up, but usually at the expense of lower peak efficiency. Blade-shape optimization, auxiliary blades, and flow-control concepts may improve start-up-related aerodynamic characteristics; yet, the reported evidence often concerns only motion initiation or low-TSR performance rather than full passive self-start. Pitch-control mechanisms appear to be the most direct way to reduce negative torque regions, but they introduce additional mechanical complexity. Overall, no reviewed solution can yet be regarded as a universally reliable passive self-start method for Darrieus turbines operating under low-wind-speed conditions. Full article

This paper presents a novel cyclone dust removal device and conducts a preliminary investigation into its internal flow field characteristics. The device is equipped with an impeller with Archimedean spiral characteristics and a whip sheath structure arranged in a circle. Using the computational fluid dynamics (CFD) method, the velocity field, pressure field, vortex structure, and fluid trajectory characteristics are studied under the condition of a fixed rotational speed and different inlet velocities. The simulation results demonstrate that, under a fixed rotational speed of 24.5 rps and TSR = 2.0, the downstream vortex system of the impeller is more coherent and structured, developing into a stable configuration with alternating positive and negative vorticity. When the whip sheath structure is added, a larger radial velocity is generated. This study reveals the unique internal flow field evolution law of the device, which provides a theoretical basis for subsequent particle separation research. Full article

The compatibility between economic profitability and environmental commitment remains key in sustainable entrepreneurship research. This study presents a 20-year longitudinal case (2006–2026) of INAMSOS, S.A., a small Spanish environmental enterprise (31 shareholders; initial valuation of €262,500, i.e., the total nominal share capital contributed by shareholders between 2006 and 2009) promoted by an ecological restoration NGO (FIRE) and linked to the University of Alcalá (UAH). The aim is to assess whether a sustainability-inspired business model can simultaneously generate economic, social, and environmental value over time. Data include corporate records, shareholder information, project documentation, and institutional linkages. Economic performance is measured through valuation changes, inflation-adjusted returns, and total shareholder return (TSR). Social and environmental dimensions are assessed via stakeholder engagement, agroecological product distribution, and support for ecological restoration. Results show an accumulated revaluation of 41.4%, above cumulative inflation (~35%), indicating a positive real return. TSR reached 59.5% nominally. Additionally, shareholders received agroecological products valued at €37,495.25 and supported €9812.5 for ecological restoration via FIRE. The case suggests that such hybrid firms can strengthen interactions among the private sector, civil society, and academia, although academic links were weaker than expected. Findings suggest that small hybrid enterprises can create multiple value forms beyond financial metrics and support sustainability transitions. Diversified investments may enhance long-term financial resilience. Evidence supports the feasibility of sustainability-oriented entrepreneurship aligned with European and global ecological restoration targets. Full article

Numerous previous investigations have exploited single-component aluminum hydroxide, silica, or phosphorus-containing organic agents to improve the fire resistance of epoxy resin. Existing literature confirms that ATH relies on endothermic dehydration and inorganic barrier layers to suppress combustion, while phosphorus organics exert radical quenching effects in the gas phase. However, separate use of these fillers generally requires high loading to achieve satisfactory flame retardancy, which inevitably weakens the mechanical properties of the epoxy matrix; few studies integrate N, P, and Si elements into ATH via chemical grafting to realize synergistic flame retardancy at low filler dosage, and the dual heat-transfer regulation effect of formed SiO₂-Al₂O₃ inorganic residues has rarely been systematically discussed in prior reports. This study presents an organic–inorganic hybrid flame retardant, SPDP-PTMS@ATH, synthesized by grafting N,P,Si-containing organic groups onto Al(OH)₃. The modified ATH retained its layered structure, as confirmed by FTIR, XPS, SEM, and XRD. At only 5 wt.% loading in epoxy, the additive significantly enhanced flame retardancy and smoke suppression: LOI increased to 33.5% (34% higher than pure EP), UL-94 reached V-0 rating, and peak HRR, THR, COPR, TSR, CO2PR, and SPR are reduced by 30.2%, 30.8%, 33.1%, 26.9%, 25.86%, and 15%, respectively. Char analysis revealed a denser, more graphitized structure with fewer defects. Moreover, tensile strength and elongation at break improved by 22.0% and 47.5%, respectively. This work demonstrates that low-loading SPDP-PTMS@ATH simultaneously boosts fire safety, smoke suppression, and mechanical performance, offering a cost-effective and sustainable route to high-performance epoxy composites. Full article

Foamed asphalt mixtures (FAMs) are considered to be among the most environmentally friendly. They are produced at temperatures ranging from 100 °C to 120 °C. In order to produce asphalt mixtures at such a low temperature, it is necessary to produce foamed asphalt binder with high foaming parameters, i.e., maximum expansion (ER) and a half-life (HLa) of the asphalt foam. Consequently, the asphalt binders were modified with a surfactant at a concentration of 0.6% by weight of the binder, prior to its foaming with water. Subsequently, an AC 8 S asphalt mixture was designed using traditional hot-mix asphalt (HMA) technology and with modified foamed asphalt binders in quantities ranging from 5.6% to 6.5% by weight, in increments of 0.3%. To ensure optimal properties of the FAM, hydrated lime was added at levels of 0%, 15%, 30% and 45% by weight as a substitute for filler. The influence of modified foamed asphalt binders and hydrated lime on the void content (Va), resistance to moisture and frost (TSR) and resistance to permanent deformation (WTS_AIR and PRD_AIR) of the FAM was assessed. A key element of the research was the determination of the complex modulus of stiffness E* and resistance to low-temperature cracking R₋₂, σ_cry, T_failure and crack propagation using the SCB methodology. Analysis of the test results using desirability functions enabled the determination of the optimum proportions of foamed asphalt binders and hydrated lime—5.9% and 30% respectively—in the FAM, ensuring that its properties meet all the requirements of the relevant standards and guaranteeing resistance to low-temperature cracking. Full article

Post-welding vibratory stress relief (VSR) has been studied extensively for its capability of decreasing welding residual stresses (RS). This study examines the effectiveness of VSR applied on butt-welded thick sheets of high-strength low-alloy steel. The effect of thermal stress relief (TSR) was examined simultaneously. X-ray diffractometry (XRD), hole drilling method (HDM), and instrumented indentation technique (IIT) were employed for evaluating RS distribution. Global mechanical properties of the weld joint were assessed using tensile tests, bending tests, and Charpy impact tests. Hardness was employed to assess local variation in mechanical properties. The microstructure was observed through light optical microscopy (LOM) and electron back-scatter diffraction (EBSD). It was found that RS redistributed after VSR. The overall decrease in RS could be seen after VSR; however, the scatter in RS increased. TSR, on the other hand, resulted in the decrease in both magnitude and scatter of RS. Peak values of the post-welding RS were evaluated in the range of −200 to 200 MPa; meanwhile, the mean RS was within the range of −100 to 100 MPa. After TSR, RS was mostly within the range of −50 to 50 MPa. After VSR, RS was found to lie mostly within the range of −100 to 200 MPa with peak values being close to the yield strength. VSR had no adverse effect on the structural integrity of the weld joint. No significant differences in the microstructure were seen among as-welded, TSR, and VSR conditions. Full article

The wide deployment of phasor measurement units has enabled data-driven transient stability prediction (TSP) of power systems. However, ensuring the reliability of TSP results is still a significant challenge that limits the practical application of data-driven methods. To this end, a convolutional neural network (CNN)-based deep ensemble model with optimized class-specific thresholds is proposed to achieve reliable TSP. Specifically, a CNN is utilized as the backbone predictor, where the time-series variables from multiple generators are transformed into image-like inputs, and a CNN-based deep ensemble model is developed to provide accurate confidence estimation for TSP. Subsequently, considering the asymmetric importance of different classes in TSP, a confidence-based class-specific thresholds rule is adopted, and a multi-objective optimization model for determining the class-specific thresholds is formulated. In this optimization model, the reliability requirement of TSP is imposed as a constraint, requiring that true unstable rate (TUR) equal to 100%, with the objectives of minimizing the rejection rate and maximizing the true stable rate (TSR). The Pareto front of the class-specific thresholds can be obtained by solving the optimization model. Test results on two benchmark power systems show that the proposed method achieves a TUR of 100% and a TSR of at least 99% with approximately 10% of the samples rejected, demonstrating its effectiveness and scalability. Full article

Warm mix asphalt (WMA) provides a sustainable way of lowering production temperatures, reducing energy use for sustainable pavement construction; however, moisture damage affects its durability. Reclaimed asphalt pavement (RAP) contains aged binder that is stiffer, harder, and more brittle than virgin binder, resulting in asphalt mixtures with higher stiffness/modulus. This review examines the effect of incorporating RAP to amend the moisture damage susceptibility of WMA. It surveys the various moisture-damage failures reported in the literature on WMA with RAP mixes, including adhesive and cohesive failures, as well as hydraulic scouring and aggregate fracture. The analysis further explains the influence of WMA technology, RAP content, rejuvenation, and interfacial chemistry on the moisture durability of WMA-RAP mixtures. The strengths and limitations of the conventional and emerging moisture damage evaluation tests, including AASHTO T 283 tensile strength ratio (TSR), boiling water test (BWT), surface free energy (SFE), and fracture-energy-based approaches, were compared. This mechanistic synthesis linking production-related moisture sources, RAP heterogeneity and practical mitigation strategies highlights why reliance on TSR alone can conceal moisture-cracking vulnerability. The synthesis clarifies how RAP changes the moisture damage susceptibility of WMA to retain the environmental, economic and social benefits and circularity without compromising durability. This review proposes a practical roadmap based on technology-specific screening, multi-metric performance evaluation, and construction quality control for more reliable WMA-RAP specifications. Full article

Flame-retardant coatings and films are widely used to delay flame spread on interior finishing and wood-based materials; however, their fire effluent toxicity has not been sufficiently characterized, and direct comparisons between these product types remain scarce. This study evaluated three commercial flame-retardant coatings and three flame-retardant films using the KS F 2271 gas toxicity test, NES 713 toxicity index test, and Py-GC/MS and HS-GC/MS analyses. Representative coating and film products were also applied to medium-density fiberboard (MDF) to assess average incapacitation time, total smoke release (TSR), and total heat release (THR). All tested specimens, including the 1 coat/layer, increased-loading, and MDF-applied conditions, satisfied the Korean gas toxicity criterion of 9 min. However, increased loading affected the two product groups differently; the intumescent coating showed a marked reduction in average incapacitation time, whereas the films remained relatively stable. The coatings produced higher toxicity indices and more diverse detected gases and pyrolysis products than the films. In MDF-based specimens, flame-retardant treatment increased average incapacitation time and reduced TSR and THR. These findings show that fire effluent toxicity differs between coatings and films and should be considered together with flame-retardant performance. Full article

This paper presents a comprehensive three-dimensional numerical investigation of a novel vertical-axis wind turbine (VAWT) characterised by a unique aerodynamic profile and a passive blade-pitch control mechanism. Unlike conventional fixed-geometry designs, the proposed turbine utilizes rectangular blades mounted on horizontal axes via articulated bearings, allowing them to rotate freely up to 90 degrees, constrained by a vertical pin-and-belt system. This configuration ensures that blades on the power-stroke side hit the vertical stopper to capture maximum wind energy, while blades on the return-stroke side open up to 90 degrees to significantly reduce aerodynamic drag. This dynamic adjustment enables the turbine to operate efficiently in low-wind conditions (3–5 m/s) while maintaining enhanced torque stability. To ensure numerical reliability, a rigorous grid independence study was performed, and the computational domain was configured to eliminate wall interference effects. The aerodynamic performance was analyzed using COMSOL Multiphysics v6.2 by solving the Reynolds-averaged Navier–Stokes (RANS) equations. Four turbulence models—SST, k–ε, k–ω, and RNG—were evaluated, with the SST model demonstrating the highest fidelity in capturing flow separation and wake structures under adverse pressure gradients. This study establishes the turbine’s performance benchmarks, including the power coefficient (C_p) versus tip speed ratio (TSR) curves. The numerical results were validated against laboratory experimental data, with excellent agreement (relative error < 5%). The findings identify the optimal geometric parameters and tangential velocity distributions that distinguish this configuration (Patent FAP 20240465) from traditional VAWTs. Finally, the successful implementation of a 2 kW prototype confirms the model’s accuracy and highlights the turbine’s potential as a stable and efficient solution for sustainable urban energy harvesting. Full article

Federated learning enables privacy-preserving training of spiking neural networks on distributed neuromorphic and event-based data, but it also exposes the global model to stealthy backdoor attacks injected by malicious clients. Compared with conventional artificial neural networks, federated spiking neural networks are more difficult to sanitize because malicious behavior may be encoded not only in spatial filters but also in spike timing, membrane dynamics, and temporal firing sparsity. Existing backdoor defenses usually require repeated federated retraining, access to client data, trigger synthesis, or computationally expensive model repair, which limits their practicality in low-power neuromorphic deployment. This paper proposes FedTSR, a fast post-training backdoor removal framework for spiking neural networks trained through federated learning. FedTSR introduces two coordinated algorithms: temporal synaptic risk estimation, which identifies backdoor-sensitive synaptic groups by measuring abnormal spike-response contributions across simulation timesteps using a small clean calibration set, and spike-consistency recalibration, which restores benign task performance through lightweight membrane-potential alignment and firing-rate regularization without restarting federated training. The proposed method is trigger-agnostic, client-independent, and compatible with surrogate-gradient trained spiking models. Here, trigger-agnostic means that FedTSR does not use trigger identity during repair; it should not be interpreted as certified robustness against every adaptive trigger family. Experiments on real neuromorphic and vision benchmarks, including N-MNIST, CIFAR10-DVS, DVS Gesture, and CIFAR-10, show that FedTSR substantially reduces attack success rate while preserving clean accuracy under multiple backdoor patterns, poisoning ratios, and non-IID federated settings. The results indicate that exploiting temporal spike dynamics provides an efficient and effective route for sanitizing compromised federated spiking neural networks. Full article

Background: The treatment of rectal cancer frequently involves a multimodal approach, including neoadjuvant therapy prior to surgery in patients with locally advanced disease. However, the response to such treatment is variable. Robust biomarkers to predict neoadjuvant therapy response represent an unmet clinical need; they could help to stratify patients for organ preservation strategies or treatment intensification. The tumour–stroma ratio (TSR) is an established prognostic marker that has recently gained attention for its potential predictive value when assessed in pre-treatment biopsies. Objective: This narrative review critically evaluates the existing evidence regarding TSR as a predictive biomarker for neoadjuvant therapy response in rectal cancer. Results: Emerging evidence from retrospective studies of large cohorts suggests that stroma-high tumours often demonstrate resistance to standard neoadjuvant chemoradiotherapy, resulting in lower major pathological response rates. Conversely, some smaller studies report no significant association between biopsy TSR and treatment efficacy. This conflicting evidence could be attributable to methodological heterogeneity, including inconsistent definitions, varying measurement techniques (manual versus automated), and mixed patient cohorts. The predictive value of TSR appears to be neoadjuvant regimen-specific, with stroma-high phenotypes interacting differently with treatments like short-course radiotherapy or intensified chemotherapy. Conclusions: TSR is a simple, biologically plausible, and readily assessable promising biomarker with apparently predictive as well as prognostic potential. It is likely to represent a regimen-specific predictor rather than a universal marker of resistance to neoadjuvant therapy in rectal cancer. Future clinical translation will require standardised, AI-driven quantification and robust prospective clinical validation. Full article

This study evaluates the 20-year operational performance (2006–2025) of a preseason prediction system for Atlantic hurricane activity developed at North Carolina State University (NCSU) and compares it with forecasts from Colorado State University (CSU), Tropical Storm Risk (TSR), and NOAA. Unlike previous studies based primarily on hindcast experiments, this analysis uses real-time forecasts generated under evolving model configurations, providing a realistic assessment of operational forecast skill. Results show that NCSU April forecasts exhibit lower mean absolute error than other April-issued forecasts and achieve performance comparable to later-issued forecasts from NOAA and CSU, indicating that improved model formulation can partially offset the advantage of later initialization. To identify the sources of forecast improvement, regression and ensemble analyses are conducted. Forecast adjustments between early- and late-season forecasts are primarily explained by changes in tropical North Atlantic sea surface temperature (SST), while ENSO contributes secondarily as forecast uncertainty decreases beyond the spring predictability barrier. These results establish a clear hierarchy of predictors, with Atlantic SST providing the dominant source of preseason predictability. Multi-model ensemble experiments further show that simple averaging does not outperform the best individual models; instead, selective combinations yield the highest skill, with optimal configurations differing between named storm and hurricane predictions, demonstrating that forecast improvement depends on combining complementary information rather than increasing ensemble size. Forecast performance is also shown to be predictand-dependent, with named storm counts more sensitive to late-spring environmental evolution and hurricane counts more strongly constrained by basin-scale thermodynamic conditions. Despite these advances, all models exhibit reduced skill during extreme seasons, reflecting the intrinsic limits of seasonal predictability. Overall, these results demonstrate that preseason hurricane forecast skill is governed by the interaction of forecast timing, model capability, and a hierarchical structure of environmental predictors, providing a unified framework for interpreting differences among forecasting systems and guiding future model development. Full article

Waste plastic aggregate (WPA) is a promising recycled material for asphalt mixtures, but its polymeric surface can weaken binder adhesion and increase moisture-related damage, even in SBS-modified systems. Therefore, a clear need exists to identify anti-stripping agents that are compatible with WPA, rather than simply increasing WPA content in asphalt mixtures. This study evaluates the interfacial and mixture-scale performance of SBS-modified asphalt mixtures containing two WPA types, namely coarse WPA and fine WPA, treated with three liquid anti-stripping agents: amine-based agent (AS-Am), organosilane coupling-type adhesion promoter (AS-OS), and ester/surfactant-based wetting agent (AS-Es). The novelty of this study lies in selecting the anti-stripping system based on WPA–binder adhesion compatibility and validating it through moisture, rutting, rheological, and fracture performance. Binder bond strength, tensile bond strength, shear bond strength, indirect tensile strength/tensile strength ratio (ITS/TSR), Hamburg wheel tracking (HWT), multiple stress creep recovery (MSCR), and semi-circular bending (SCB) tests were conducted. AS-OS showed the best overall performance. It increased binder bond strength (BBS) by 52.8% for coarse WPA and 61.5% for fine WPA, while the optimum 0.5% dosage improved tensile bond strength by 81.0% and 97.2%, respectively. AS-OS also increased shear strength by 58.8–68.3% and improved TSR to 89.0% and 86.2%. In HWT, C-OS and F-OS reduced final rut depth by 44.0% and 45.8%, respectively. SCB results further showed higher fracture work, especially for F-OS. The findings indicate that proper anti-stripping chemistry is essential for durable WPA–SBS asphalt mixtures. Full article