Stress Coupling Analysis and Failure Damage Evaluation of Wind Turbine Blades during Strong Winds

Blades in strong wind conditions are prone to various failures and damage that is due to the action of random variable amplitude loads. In this study, we analyze the failure of 1.5 MW horizontal axis wind turbine blades. The computational fluid dynamics unsteady calculation method is used to simulate the aerodynamic load distribution on the blade. Fluid–structure coupling methods are applied to calculate the blade stress. The results show that the equivalent stress of the blade is the largest when the azimuth angle is 30°, and the maximum equivalent stress is 20.60 MPa. There are obvious stress peaks in six sections, such as r/R = 0.10 (the span length of blade/the full length of the blade = 0.10). The frequency of damage that is caused by the stress in each area of the blade is determined based on the blade damage. The frequency of gel coat cracking in the blade tips and leaves is 77.78% and 22.22%, respectively, and the frequency of crack occurrence is 87.75%, 10.20% and 2.05%, respectively. By combining the stress concentration area and the damage results, the cause of blade damage is determined, which can replace the traditional inspection methods and improve the inspection efficiency

Stress Coupling Analysis and Failure Damage Evaluation of Wind Turbine Blades during Strong Winds

Blades in strong wind conditions are prone to various failures and damage that is due to the action of random variable amplitude loads. In this study, we analyze the failure of 1.5 MW horizontal axis wind turbine blades. The computational fluid dynamics unsteady calculation method is used to simulate the aerodynamic load distribution on the blade. Fluid–structure coupling methods are applied to calculate the blade stress. The results show that the equivalent stress of the blade is the largest when the azimuth angle is 30°, and the maximum equivalent stress is 20.60 MPa. There are obvious stress peaks in six sections, such as r/R = 0.10 (the span length of blade/the full length of the blade = 0.10). The frequency of damage that is caused by the stress in each area of the blade is determined based on the blade damage. The frequency of gel coat cracking in the blade tips and leaves is 77.78% and 22.22%, respectively, and the frequency of crack occurrence is 87.75%, 10.20% and 2.05%, respectively. By combining the stress concentration area and the damage results, the cause of blade damage is determined, which can replace the traditional inspection methods and improve the inspection efficiency

Seed soaking with melatonin promotes seed germination under chromium stress via enhancing reserve mobilization and antioxidant metabolism in wheat

Chromium (Cr) pollution has serious harm to crop growth, while little is known on the role of melatonin (MT) on seed germination and physiology in Cr-stressed wheat. The effects of seed soaking with MT on growth, reserve mobilization, osmotic regulation and antioxidant capacity of wheat seeds during germination under hexavalent chromium (100 μM) stress were investigated. The results indicated that Cr toxicity decreased the seed germination rate by 16% and suppressed the growth of germinated seeds compared to unstressed seeds. MT in the concentration-dependent manner increased germination rate and promoted subsequent growth when seeds were exposed to Cr stress, but the effect could be counteracted at high concentration. Seed soaking with MT (100 μM) markedly decreased Cr accumulation in seeds, radicals and coleoptiles by 15%, 6% and 15%, respectively, and enhanced α-amylase activity and soluble sugar and free amino acids content in seeds to improve reserve mobilization under Cr stress, compared with Cr treatment. Furthermore, decreasing the level of osmotic regulators (soluble sugar and soluble protein) in radicles under MT combined with Cr treatment confirmed the reduction of osmotic stress caused by Cr stress. Importantly, MT pretreatment reduced H2O2 content by 19% and O2·− release rate by 45% in radicles under Cr toxicity compared with Cr-stressed wheat, in terms of promoting scavenging ability and decreasing production ability, which was to upregulate the activities and encoding genes expression levels of superoxide dismutase (SOD), catalase (CAT), ascorbic acid peroxidase (APX) and peroxidase (POD) and to downregulate plasma membrane-bound NADPH oxidase (NOX) encoding genes (TaRbohD, TaRbohF) expression, respectively. In all, these results provided evidence that seed soaking with MT could be a potentially method to protect wheat seeds from Cr toxicity, which effectively ameliorated germination under Cr stress by enhancing reserve mobilization and antioxidant metabolism in wheat

N-Acetylglucosamine mitigates lung injury and pulmonary fibrosis induced by bleomycin

Lung injury and pulmonary fibrosis contribute to morbidity and mortality, and, in particular, are characterized as leading cause on confirmed COVID-19 death. To date, efficient therapeutic approach for such lung diseases is lacking. N-Acetylglucosamine (NAG), an acetylated derivative of glucosamine, has been proposed as a potential protector of lung function in several types of lung diseases. The mechanism by which NAG protects against lung injury, however, remains unclear. Here, we show that NAG treatment improves pulmonary function in bleomycin (BLM)-induced lung injury model measured by flexiVent system. At early phase of lung injury, NAG treatment results in silenced immune response by targeting ARG1+ macrophages activation, and, consequently, blocks KRT8+ transitional stem cell in the alveolar region to stimulate PDGF Rβ+ fibroblasts hyperproliferation, thereby attenuating the pulmonary fibrosis. This combinational depression of immune response and extracellular matrix deposition within the lung mitigates lung injury and pulmonary fibrosis induced by BLM. Our findings provide novel insight into the protective role of NAG in lung injury

DataSheet_1_Low red/far-red ratio can induce cytokinin degradation resulting in the inhibition of tillering in wheat (Triticum aestivum L.).docx

Shoot branching is inhibited by a low red/far-red ratio (R/FR). Prior studies have shown that the R/FR suppressed Arabidopsis thaliana branching by promotes bud abscisic acid (ABA) accumulation directly. Given that wheat tiller buds are wrapped in leaf sheaths and may not respond rapidly to a R/FR, systemic cytokinin (CTK) may be more critical. Here, systemic hormonal signals including indole-3-acetic acid (IAA), gibberellins (GA) and CTK and bud ABA signals in wheat were tested under a low R/FR. The results showed that a low R/FR reduced the percentage of tiller occurrence of tiller IV and the tiller number per plant. The low R/FR did not rapidly induced ABA accumulation in the tiller IV because of the protection of the leaf sheath and had little effect on IAA content and signaling in the tiller nodes. The significant change in the CTK levels was observed earlier than those of other hormone (ABA, IAA and GA) and exogenous cytokinin restored the CTK levels and tiller number per plant under low R/FR conditions. Further analysis revealed that the decrease in cytokinin levels was mainly associated with upregulation of cytokinin degradation genes (TaCKX5, TaCKX11) in tiller nodes. In addition, exposure to a decreased R/FR upregulated the expression of GA biosynthesis genes (TaGA20ox1, TaGA3ox2), resulting in elevated GA levels, which might further promote CTK degradation in tiller nodes and inhibit tillering. Therefore, our results provide evidence that the enhancement of cytokinin degradation is a novel mechanism underlying the wheat tillering response to a low R/FR.</p