Search Results (458)

Cold bending provides a cost-effective method for fabricating triangular glass units for free-form architectural envelopes. Replacing conventional continuous edge constraints with discrete point clamps reduces over-constraint but introduces pronounced bending–membrane coupling in the unsupported spans between adjacent clamps. Consequently, the mechanisms governing local instability and optical-quality degradation remain insufficiently understood. In this study, cold-bending tests were performed on isosceles triangular fully toughened glass plates to measure out-of-plane deflection and surface-strain evolution. The experimental data were then used to establish and validate an Abaqus finite element model for systematic parametric analysis. Based on von Kármán’s large-deflection theory, a semi-empirical reduced-order framework that combines modal superposition with the response-surface method was developed to identify instability-sensitive configurations. The results show that, under weak constraints and large vertex angles, the panel response changes from a bending-dominated regime to a strongly nonlinear large-deflection regime governed by membrane effects; this transition is marked by a reversal of mid-span deflection and a compressive-to-tensile stress transition. Increasing the number of clamps from two to four substantially suppresses both global and local distortion by shortening the free spans and redistributing membrane strain energy, reducing peak mid-span deflection by 47–68%, and satisfying the EN 12150-1 limits for both bow deformation and local distortion. The height-to-base ratio is the dominant geometric parameter controlling instability. Under two-point support, a critical response turning point occurs at a height–base ratio of approximately 0.5 before the material fracture limit is reached, defining a geometric boundary below which optical serviceability failure accelerates. These findings provide a theoretical basis and quantitative engineering guidance for optimizing the cold-bending process of isosceles triangular fully toughened glass plates. Full article

Due to their higher installation position and smaller diameter compared to conductors, DC overhead ground wires are more susceptible to severe icing during cold waves. To investigate the icing growth characteristics of ultra-high voltage (UHV) DC ground wires under the coupled effect of flow and electric fields, this study considers the unique operational conditions of UHV DC ground wires. Based on the physical processes of charged droplet motion, flow-around, collision, and freezing around the ground wire, a numerical model for simulating icing under the coupled flow-electric field interaction is established. The influence of factors such as wind speed, droplet size, and icing morphology on icing development under the coupled field is numerically analyzed. Furthermore, observations of icing morphology on UHV ground wires under natural conditions were conducted. The results indicate that under icing conditions, charged droplets of different sizes exhibit significant differences in trajectory deviation during flow-around and collision with the ground wire, with larger droplets being more significantly affected by the electric field force. Under the influence of the electric field, the local droplet collision coefficient on the ground wire surface can increase by 3.4% to 128.9%. Compared to uncharged conditions, icing coverage under charged conditions extends from the windward side to the leeward side, and the icing rate increases accordingly. Natural observations reveal that icing on the ground wire surface under the DC electric field often forms protruding ice tips, which enhance electric field concentration, leading to increased local droplet collision coefficients and icing rates. This, in turn, further promotes the formation of irregular and rough ice accretion. The findings of this study provide technical insights for predicting and simulating icing on UHV DC ground wires. Full article

A microscale vortex embedded in a cold front over the Pearl River Estuary was observed by weather radars in Hong Kong on the evening of 2 March 2026. This paper presents an observational and simulation study of this vortex. In addition to the reflectivity and Doppler velocity data, the three-dimensional wind field associated with this vortex was analyzed using two radar-based analysis methods. Updrafts were present within the vortex, and the formation of the vortex appears to be related to the horizontal wind shear within the frontal zone and vertical motion triggered by a mid-tropospheric wave. Three commercial aircraft flew across the vortex at low altitude southwest of Lantau Island. Flight data showed marked fluctuations in vertical velocity, including both upward and downward air motions, together with severe turbulence within the vortex. The vortex is therefore of both meteorological interest and operational significance for aviation safety. The event was also simulated using the Weather Research and Forecasting (WRF) model with 200 m resolution. The model reproduced the observed vertical motions and turbulence intensity reasonably well in comparison with aircraft observations. Sensitivity tests with varying sea surface temperature and local terrain over Hong Kong showed no significant impact on the formation of the vortex, confirming that the event was primarily driven by horizontal wind shear in the frontal zone and vertical motion triggered by mid-tropospheric waves. Full article

Urban street canyons exert a critical influence on local microclimates; however, the dynamics of mixed convective airflow under unsteady wind and thermal forcing remain poorly quantified. This study systematically investigates the spatiotemporal characteristics of airflow within symmetric and asymmetric street canyons through integrated long-term field measurements and complementary CFD simulations. Field data collected over 120 monitoring days at the Weishui Campus of Chang’an University were analyzed using the Levenberg–Marquardt nonlinear curve-fitting algorithm. The analysis demonstrates that sine functions accurately represent diurnal surface temperature variations during consecutive clear sky periods, whereas polynomial functions of varying orders are required to characterize meteorologically complex episodes, including cold-wave cooling and seasonal transitions. Ambient wind patterns outside the canyon were further classified into two characteristic variation modes: stepwise and gradual. Complementary unsteady RANS simulations, with wall boundary conditions derived directly from the fitted field data, reveal that canyon geometry and meteorological forcing jointly govern the evolution of airflow structures and thermal distributions across seasons. In the symmetric canyon, the flow transitions from complex multi-vortex activity in spring and summer to a more stable regime in autumn, with two well-defined counter-rotating vortices emerging during winter cold-wave events. In the asymmetric canyon, strong summer solar heating sustains a dominant leeward vortex with a strengthening secondary structure, whereas winter cold wave intrusion generates a hierarchically nested vortex system in which secondary and tertiary vortices progressively develop and detach. By coupling empirical surface temperature functions with CFD boundary conditions, this study advances the precision of predictive microclimate models and provides an evidence-based framework for optimizing street canyon geometry to enhance ventilation performance, energy efficiency, and outdoor thermal comfort. Full article

The use of underutilized biomass improves resource-use efficiency and reduces agricultural waste, particularly in temperate systems cultivating tropical crops. Papaya (Carica papaya L.), grown as an annual crop in these systems, produces substantial trunk biomass that is typically discarded after harvest. This study evaluated the potential of papaya trunk xylem rays as an edible resource through compositional, sensory, and functional analyses. Trunks were harvested at the end of the fruiting period (December) and after exposure to a cold wave (January) and were classified by organ types and maturity level. Xylem rays showed moisture and carbohydrate contents comparable to those of green papaya fruit, and were judged as edible by all panelists (100%) in December-harvested samples. However, exposure to a cold wave reduced sweetness and increased bitterness, resulting in decreased overall acceptability. Nevertheless, boiling effectively reduced bitterness and improved palatability even in cold-exposed samples. In addition, xylem rays exhibited higher total polyphenol content than green papaya fruit, while showing comparable DPPH radical scavenging activity. These results suggest that xylem rays have potential as an edible plant resource with antioxidant-related properties, contributing to resource-use efficiency and potentially providing opportunities for biomass valorization in temperate production systems. Full article

The frequent occurrence of extreme climate events poses a severe challenge to the reliability of building energy systems. Hydrogen energy, with its long-term storage capacity, has become a key technology carrier for enhancing building resilience. This study constructs a resilience–environment–economy co-optimization framework that couples dynamic simulation and emergy analysis. Through a five-in-one approach of physical modeling, climate scenario generation, resilience quantification, emergy accounting, and multi-objective optimization, the resilience performance of building hydrogen energy systems under the scenario of extreme heat waves combined with grid failure is evaluated. The results show that the thermal time constant deviation of the electrolyzer is 4.06%, the correlation coefficient between the generated heat wave scenario sequence and the historical measured data is 0.94, the prediction deviation of the once-in-a-century extreme temperature is 0.5%, the environmental load rate is 4.33, the Pareto front contains 127 non-dominated solutions, and the comprehensive performance of the co-optimal solution is improved by 42% to 88%. Engineering suggestions: For public buildings in hot summer and cold winter regions, the hydrogen energy system should adopt a configuration of 50–60 kW electrolyzers and 50–70 kg hydrogen storage tanks, with a key load guarantee rate of no less than 95%, and the ecological cost is 35% lower than that of diesel backup. This study provides a quantitative decision-making tool for the resilience planning of building hydrogen energy systems under extreme climate conditions and can be extended to other high climate risk areas. Full article

The continuously improving power density of Li-ion batteries and the widespread application of fast charging and discharging have rendered thermal management an increasingly critical task. Cold plates are among the most important means for such a task, and their channel structure significantly affects battery performance. Aiming to further improve the thermohydraulic performance of cold plate, this study proposes a cold plate with sinusoidal wave-shaped channel. Using channel quantity, amplitude, wavelength, diameter, and coolant mass flow rate as variables, the orthogonal experimental scheme is employed to design combinations of different variables for numerical simulation. The numerical simulation results are used to train a deep neural network for cold plate performance prediction. The trained neural network can accurately predict the maximum temperature, comprehensive performance indicators, and entropy generation rate with errors below 5.0%, 5.0%, and 10.0%, respectively. Multi-objective optimization design (MOOD) is implemented by combining a deep neural network with the NSGA-II genetic optimization, yielding two sets of Pareto fronts as follows: one for maximizing comprehensive performance indicator and minimizing entropy generation rate, and the other for minimizing maximum temperature and entropy generation rate, and TOPSIS decision points are provided. This study provides a new method and valuable MOOD results for the thermal management of Li-ion batteries and cold plate engineering while offering theoretical guidance for practical applications. Full article

The next generation of space-based gravitational wave observatories, such as LISA, TianQin, and Taiji, requires ultra-precise drag-free control and therefore micro-propulsion systems with thrust noise below $0.1\mathsf{\mu }\mathrm{N}/\sqrt{\mathrm{Hz}}$. This paper presents the design and experimental validation of a high-precision pressure regulation unit (PRU) for cold-gas micro-propulsion, guided by a requirement-driven analysis of pressure-induced thrust-noise sensitivity. A first-order mapping translates the mission-level thrust-noise constraint into a subsystem-level pressure-stability target, yielding an upper bound of about $50\mathrm{Pa}/\sqrt{\mathrm{Hz}}$ and an adopted design budget of about $40\mathrm{Pa}/\sqrt{\mathrm{Hz}}$. On this basis, a dual-stage architecture integrating solenoid pre-conditioning and piezoelectric fine regulation is developed. Stochastic simulations indicate that thermal drift dominates at very low frequency, whereas pressure fluctuation is the dominant contributor in the main $0.01$–$1\mathrm{Hz}$ control band under the adopted budget. Experimental validation under three operating modes shows that solenoid-only regulation provides the smallest performance margin, that the piezoelectric stage significantly improves outlet stability, and that the integrated dual-stage configuration achieves the strongest pressure-noise suppression in the mission-relevant sensitive band. These results provide a subsystem-level pressure-conditioning basis for the further development of high-precision cold-gas micro-propulsion systems for future drag-free missions. Full article

The response of temperature extremes to recent warming at the local scale remains uncertain because changes in mean temperature may be accompanied by changes in the shape of the temperature distribution. While higher mean temperatures generally lead to more frequent heat waves and fewer cold events, variations in higher-order statistical moments can either amplify or moderate these effects. This study examines how the probability distribution of 2 m temperature has evolved during the last 80 years in Greece using the ERA-5 reanalysis dataset. The evolution of the first four statistical moments (mean, standard deviation, skewness and kurtosis) and of the 5th and 95th percentiles of daily mean temperature is calculated by splitting the time series into eight decades, with each decade representing a separate climatology. A clear increase in mean temperature is observed across Greece. However, trends in the higher-order moments are more complex: the standard deviation and skewness exhibit positive and negative trends that depend on the region and the season, while kurtosis trends are weaker with a few regional exceptions. These changes alter the response of temperature extremes to warming, resulting in non-uniform shifts of the 5th and 95th percentiles. In mountainous regions, extreme cold events during winter and autumn have decreased more strongly than expected from mean warming alone, while in marine regions extreme warm events during summer and autumn have increased beyond what would be expected by a shift in the mean. In other areas, changes in the distribution shape lead to weaker extremes than those predicted by mean warming alone. These results highlight the role that changes in temperature variability have in modulating the evolution of temperature extremes under climate warming. Full article

Temperature extremes represent a major constraint for the cultivation of yellow passion fruit (Passiflora edulis Sims f. flavicarpa), a tropical crop increasingly exposed to heat waves and chilling events under climate change. Glycine betaine (GB) is a widely studied osmoprotectant in plants, yet its influence on metabolic responses of passion fruit under contrasting temperature stresses remains poorly characterized. This study investigated the effects of exogenous GB on primary metabolite profiles of passion fruit seedlings subjected to heat (25, 35, and 45 °C) and cold (25, 15, and 5 °C) conditions. Seedlings were treated with GB (100 mM) or left untreated, and leaf metabolites were quantified using GC–MS-based metabolomics. Heat exposure was associated with pronounced changes in amino acids, organic acids, sugars, polyamines, and γ-aminobutyric acid (GABA), while GB-treated plants showed altered levels of proline, GABA, polyamines, and selected tricarboxylic acid intermediates. Under cold conditions, several amino acids and organic acids decreased, whereas soluble sugars accumulated, particularly in GB-treated plants. Principal component analysis revealed distinct metabolic configurations under heat and cold treatments and indicated that GB modified metabolite profiles in a stress-dependent manner rather than restoring control-like states. These findings describe how GB is associated with shifts in central carbon and nitrogen metabolism under contrasting temperature regimes, providing a metabolomic perspective on stress-related metabolic adjustments in passion fruit. Full article

Background/Objectives: Laryngeal leukoplakia and dysplasia carry a variable risk of malignant transformation. Although microlaryngoscopic excision is standard of care, data on voice function are limited. Multidimensional diagnostics, including the Vocal Extent Measure (VEM), were employed to assess pre- and postoperative status while identifying factors associated with vocal outcomes. Methods: This retrospective cohort included 44 patients with histologically confirmed vocal fold leukoplakia or dysplasia. All underwent cold steel or laser-assisted phonomicrosurgery. Voice assessments were conducted pre- and three months postoperatively, comprising videolaryngostroboscopy, auditory-perceptual evaluation of grade, roughness and breathiness (GRB), self-assessment (Voice Handicap Index, VHI-9i), and objective acoustic-aerodynamic measures. Results: Overall, 57% of patients were active smokers; 73% consumed alcohol. Lesions were mostly unilateral (77%), craniomedially localized (65%), and involved up to one-third of the vocal fold (48%), with impaired mucosal wave (76%). Histopathology revealed mainly hyperkeratosis (52%) and dysplasia (35%). Recurrence rate was 14%, with histology unchanged. Postoperatively, subjective measures showed significant improvements (post- vs. preoperative), with decreased VHI-9i scores (10 vs. 14) and GRB ratings (p < 0.05). Objective measures showed positive trends, including enhanced vocal capacity (VEM 85 vs. 82), stability (jitter 0.6 vs. 0.8%), and aerodynamics (maximum phonation time 18 vs. 15 s). Phonosurgical method, histopathology, and age did not significantly affect voice outcomes; however, higher dysplasia grades and younger age showed trends toward greater VEM gains. Conclusions: Phonomicrosurgical excision of laryngeal leukoplakia and dysplasia effectively preserves or enhances vocal function. The VEM provides a reliable, quantitative complement to established voice diagnostics and should be integrated into standardized assessment protocols. Full article

Cosmology is living through fascinating times, where new observations from ground and space telescopes are questioning the established paradigm, the so-called $\mathsf{\Lambda }$ Cold Dark Matter model. The particle nature of Dark Matter is severely constrained by underground experiments, while recent observations by galaxy surveys indicate that the cosmological constant ($\mathsf{\Lambda }$) may not be constant after all. Furthermore, observations at high redshift of fully formed galaxies with massive black holes at their centers by the James Webb Space Telescope, as well as black holes with unexpected properties observed by the LIGO-Virgo gravitational wave detectors, are driving an in-depth revision of our assumptions in models of structure formation and the evolution of the Universe. I propose exploring two new paradigms to account for Dark Matter and Dark Energy, based on known physics, without introducing new particles into the Standard Model of Particle Physics. I will extend the primordial spectrum of fluctuations to small scales with new statistical properties to provide a viable Primordial Black Hole scenario for Dark Matter, and will include non-equilibrium thermodynamics in the expanding Universe, in the form of General Relativistic Entropic Acceleration, to explain Dark Energy. My proposal could provide a unified explanation for a plethora of interrelated multi-epoch, multi-scale, and multi-probe observations from present and future Gravitational Wave detectors, Large Scale Structure observatories, and Cosmic Microwave Background experiments. It emphasizes the need to develop new theoretical ideas hand-in-hand with observations to acquire a deeper understanding of our universe. If these ideas are correct, they will open a new window into the early universe and a new fundamental understanding of gravity in the late universe. Full article

Bird migration is an awe-inspiring phenomenon that causes massive global shifts in bird distributions twice a year. To understand the evolution of this phenomenon, it is crucial to know the mortality costs of these journeys. Extreme weather-related events can lead to abnormally high mortality rates among migratory birds, while high mercury concentration may reduce the survival of songbirds in the field, especially for the long-distance migrant insectivores. Yet the specific vulnerability factors remain largely unknown. We collected the opportunistic dead Eastern Red-rumped Swallows (Cecropis daurica) in a mass-mortality event caused by a cold wave in autumn migration in Southern China. Mercury concentration in their tail feathers is 0.57 ± 0.37 µg g⁻¹, lower than the established toxicity threshold for birds. The claws’ hydrogen stable isotopic (δD) values ranged from −116 to −78 ‰, with a mean of (−88.00 ± 8.22) ‰. Stable hydrogen isotopes indicated broad origins for the Eastern Red-rumped Swallows, ranging from ~30° N to ~62° N and ~10° E to ~150° E. Considering subspecies ranges, most of the dead swallows likely came from their almost furthest breeding sites. Our results indicated the primary cause of the mass-mortality event was likely fatigue or starvation resulting from long-distance flight during an extreme cold wave. Mercury exposure may not be the main direct cause of death. Full article

In this investigation, the nonlinear dust-acoustic waves in the lunar terminator region are studied in a three-component complex plasma comprising Boltzmann-distributed electrons and ions and inertial, cold, negatively charged dust grains. The fluid model is reduced, via the reductive perturbation technique, to a planar Korteweg–de Vries (KdV) equation that governs the evolution of small-amplitude dust-acoustic structures in this environment. Hirota’s direct method is then employed to derive exact multiple-soliton solutions, which allow us to examine the parameter dependence of dust-acoustic solitons and to characterize their overtaking collisions. The analysis shows that the soliton polarity and amplitude are controlled by the equilibrium electron–ion density ratio and the electron-to-ion temperature ratio, and that multi-soliton interactions remain elastic, with only finite phase shifts after collision. In the second part of the study, the planar integer KdV model is generalized to a time-fractional KdV (FKdV) equation to incorporate nonlocal temporal memory effects in the dust-acoustic dynamics. This FKdV equation is analyzed using two analytical approximation schemes: the Tantawy technique, recently proposed as a direct and rapidly convergent approach to fractional evolution equations, and the new iterative method, a widely used high-accuracy scheme in the fractional literature. For both methods, higher-order approximations are constructed, and their absolute and global maximum residual errors are quantified. The results demonstrate that the Tantawy technique provides compact approximations with superior accuracy and stability compared with the new iterative method for the present FKdV-soliton problem. The combined integer- and fractional-analytic framework provides a physically transparent framework for understanding how nonlinearity, dispersion, and fractional memory jointly shape dust-acoustic solitary structures in the electrostatically complex lunar terminator plasma, which is of paramount interest for future lunar missions like Luna-25 and Luna-27. Full article

Winter rapeseed (Brassica rapa L.) is an important crop for vegetable oil production in China. However, its productivity is frequently threatened by severe cold waves during winter. To investigate the role of the microtubule cytoskeleton in cold adaptation of winter rapeseed, a microtubule stabilizer paclitaxel (Tax) and a microtubule depolymerizer colchicine (Col) were sprayed on winter rapeseed and transgenic proBrAFP1 Arabidopsis, respectively. The mRNA levels of cold-induced genes, along with cell membrane stability, antioxidant enzyme activities, and hormone levels were assessed under cold stresses of 4 °C and −4 °C. The results showed that low temperature significantly activated the proBrAFP1 promoter activity and increased the mRNA levels of core cold signaling pathway genes, such as C-REPEAT BINDING FACTORS (CBFs), Cyclic Nucleotide-Gated Channel (CNGC), OPEN STOMATA 1 (OST1) and Inducer of CBF EXPRESSION 1 (ICE1). Notably, under low-temperature stress, exogenous application of the microtubule stabilizer Tax markedly suppressed proBrAFP1-driven reporter activity in transgenic Arabidopsis, with consistent inhibition observed across both stem and leaf tissues; meanwhile, the Tax application alleviated reactive oxygen species (ROS) accumulation and mitigated membrane damage. In contrast, under the same low-temperature stress, the Col treatment exacerbated oxidative stress, enhanced lipid peroxidation, and elevated membrane damage. Collectively, these findings establish that microtubule regulators play indispensable roles in the cold stress response of winter rapeseed. It provides new insights into the mechanism by which plant microtubule cytoskeleton regulators mediate the cold response. Full article