► Acoustic plasticity was modeled based on the crystal plasticity theory. ► Vibration energy results in temporary softening and residual hardening. ► The stress decrease during the vibration is ...proportional to the vibration amplitude. ► The acoustic residual hardening is affected by the vibration duration and magnitude. ► The acoustic residual hardening is time-dependent rather than strain-dependent.
It is known that high-frequency vibration affects metal plasticity during metal forming and bonding operations. Metal plasticity is significantly affected by the acoustic field leading to acoustic softening and acoustic residual hardening. In this study, a modeling framework for the acoustic plasticity was proposed based on the crystal plasticity theory. The acoustic softening and acoustic residual hardening effects were modeled based on the thermal activation theory and dislocation evolution theory, respectively. To validate the developed model, vibration-assisted upsetting tests were conducted using pure aluminum specimens. Results showed that the stress decrease due to the acoustic softening was proportional to the vibration amplitude. Moreover, the acoustic residual hardening effect was influenced by the vibration amplitude and duration. The unified acoustic plasticity model accurately captured the acoustic softening and hardening in aluminum. The predicted stress–strain response of the vibration-assisted upsetting agreed well with the experimental results. The findings confirmed the significant effects of high-frequency vibration on metal plasticity and provided a basis to understand the underlying mechanisms of vibration-assisted forming.
To study the effect of the bonding area on the dynamic failure process of a reinforced concrete beam with the same reinforcement ratio, the experimental and numerical researches on the impact ...response of notched reinforced concrete beams in the low-velocity regime (≤2.5 m/s) are presented. The tests are carried out with a drop hammer impact testing machine and then the structural responses under different impact velocities are analyzed. Additionally, the dynamic three-point bending simulation for specimens with different bonding areas, but the same reinforcement ratio is conducted. In this numerical model, the parameters of a cohesive model verified from a steel bar pullout test are applied to the bonding layer to simulate the bond-slip behavior of steel bars. Then, the energy dissipation for each component (e.g., concrete, a steel bar, and the bonding layer) are compared and discussed. The dynamic experimental results suggest that the energy absorbed during the impact process increases with the growth of the impact velocity, while the effect of the impact velocity on the reaction force can be ignored. The numerical results indicate that the failure pattern changes from a bending failure to shear failure with the increase in the bonding area and impact velocity. With the growth of the bonding area, the steel bars reach the plastic stage easily and the internal energy dissipation of the bonding layer decreases, which protects the bonding effect between the steel bar and concrete effectively.
To explore and compare the failure modes, deformation behaviors, and load-bearing capacities of single-edge notched (SEN) beams strengthened with carbon fiber-reinforced polymer (CFRP) and steel ...bars, static and dynamic three-point bending tests on both types of concrete beams have been carried out in this study. During the static tests, the electro-hydraulic servo machine served as a loading device to apply pressure to CFRP beams and reinforced concrete (RC) beams. During the impact experiments, different impact velocities were imparted by adjusting the drop hammer's height. Thus, information regarding crack propagation, energy absorption, and deformation was obtained. The results from the static tests showed that the RC beams predominantly experienced shear failure. In contrast, the CFRP beams primarily exhibited bending-shear failure, attributed to the relatively weaker bond strength between the bars and the concrete. Impact tests were conducted at three different velocities in this study. As the impact velocity increased, both types of concrete beams transitioned from bending failure to bending-shear failure. At the lowest velocity, the difference in energy absorption between beams reinforced with different materials was insignificant during the bending process. However, at the highest velocity, CFRP beams absorbed less energy than RC beams. The study of structures' impact failure modes and their mechanical characteristics offers valuable references for the anti-collision design and protection of structures.
•China's offshore raft and cage aquaculture areas were extracted in 2018, with an accuracy of 87 %.•Offshore aquaculture areas were mostly distributed in estuaries, harbors, and islands.•Raft ...aquaculture is mostly distributed in the northern and central coasts of China.•Cage aquaculture is mostly distributed in the southern coasts of China.•The difference is mainly caused by satellite image phases and statistical errors.
Based on Landsat 8 remote sensing images, a combination of an unsupervised classification algorithm and artificial review was used to extract areas for Chinese offshore raft and cage aquaculture in 2018. The results of the extraction showed that China’s 2018 coastal zone raft aquaculture area comprised 194,110 ha, of which the province having the largest raft aquaculture area was Jiangsu (28.77 %), followed by Fujian (20.42 %) and Shandong (13.11 %). The cage aquaculture area covered 57,847,799 square meters, of which the provinces with the largest cage aquaculture area were Fujian (64.81 %), Guangdong (17.45 %), and Liaoning (5.63 %). In addition, by combining high-resolution remote sensing image visual interpretation and field investigation, the classification of 1200 sample points in four regions was determined, and the accuracy of the aquaculture area extraction was found to be 87.35 %. The extraction results can be used not only to evaluate China’s aquaculture production but also offer significant reference value for scientific planning related to sea use, ecological environmental protection, and marine disaster prevention and mitigation.
Most current research on aquaculture ponds focuses on coastal areas, leaving a gap in understanding of inland regions, such as the strategically significant Yangtze River Economic Belt in China. This ...study introduces an intelligent extraction method for extensive monitoring of aquaculture ponds in Yangtze River Economic Belt, using Landsat and Sentinel data from 1985 to 2020 with five-year intervals based on the Google Earth Engine (GEE) platform. Land cover change data were also analyzed to understand the impact of aquaculture-related changes. Results indicate a significant increase in aquaculture ponds in the Yangtze River Economic Belt from 3235.51 km2 to 14,207.08 km2 between 1985 and 2020. Aquaculture activity primarily shifted eastward from 1985 to 2015, then westward from 2015 to 2020. Approximately 2018.36 km2 of aquatic areas underwent conversion, mainly to water bodies or croplands, with fewer transitions to impervious surfaces, grasslands, or forests. This study highlights that inland areas can also experience significant increases in aquaculture ponds, particularly alongside large rivers, and that the environmental impacts of these changes differ from those in coastal areas, warranting specific attention.
•Blast response of gradient honeycomb sandwich panels were examined.•Influence of core arrangement on the blast response were investigated.•The energy absorption of gradient cores was calculated.•The ...use of basalt FMLs can enhance the blast resistance of sandwich panels.
In this paper, the blast responses of fiber metal laminates (FMLs) and gradient aluminum honeycomb sandwich panels with FML as skins were experimentally investigated. The woven basalt fabric was chosen as the composite reinforcement in FMLs due to its excellent mechanical and eco-friendly properties. Five different core layer arrangements were considered for sandwich panels in the experiments by arranging honeycomb core layers with different cell geometric dimensions. The deformation/failure modes of sandwich panels were obtained in the experiments, in terms of FML face-sheets and gradient honeycomb cores. The energy absorption of gradient honeycomb cores was quantitatively analyzed by digitizing the deformation/failure region of cores. The results showed that the use of basalt FMLs as face sheets can greatly enhance the blast resistance of sandwich panels compared with that with aluminum sheets as skins. The blast resistance of gradient sandwich panels not only depends on the geometric dimensions and arrangements of core layers, but also related to the intensity of target load which will cause different deformation/failure mechanism of panels. Thus, in order to obtain the best blast resistance, a well-design gradient sandwich panel should have suitable core layer arrangements and geometry to satisfy the intensity of target blast load. The results obtained from current study can give valuable reference to the using of sandwich panels in engineering protection field.
Against the backdrop of frequent extreme climates and international consensus on green and low-carbon development, Environmental, Social, and Governance (ESG) has progressively drawn increasing ...attention. Integrating the perspectives of stakeholder theory and signaling theory, this study employed the Malmquist-Luenberger productivity index, fixed-effects regression model, mediating effect model, propensity matching score difference-in-differences model, and a two-stage least squares method. Using the research sample of Chinese A-share listed companies between 2011 and 2021, the mechanisms linking ESG ratings and each component (the individual scores of E, S, and G) with the green innovation and green total factor productivity (GTFP) of enterprises were investigated. This study conducted heterogeneity analysis integrating regional, industry, and enterprise dimensions, fully considered the potential endogeneity issues, and conducted multiple robustness tests by exploring alternative approaches, replacing the measures of indicators, and reducing the research sample. The results demonstrated that higher ESG ratings significantly improved the green innovation and GTFP of enterprises. This improvement was achieved through the stakeholders and signaling mechanisms, and was more prominent in economically underdeveloped regions, patent-intensive industries, and industries with lower environmental risk. In addition, the impact varied among enterprises with different property rights. The findings elucidate the pathways through which soft regulation influences micro-level corporate decision-making, making significant contributions to the literature. Furthermore, this study provides a theoretical foundation and policy reference for constructing a positive feedback loop mechanism for ESG ratings and promoting the green transformation and upgrading of enterprises.
•The mechanisms linking ESG ratings with green transformation were investigated.•Constructed a theoretical model that combines stakeholder and signaling theories.•Higher ESG ratings significantly improved the green innovation and GTFP.•Theoretical basis for a feedback loop mechanism for ESG ratings was provided.
The aim of this study was to explain the lncRNA MEG3 had anti-cancer effects to suppress cervical carcinoma biological activity.
The Hela cell were divided into three groups (NC group,BL group and ...lncRNA group). The cells of lncRNA or BL groups were transfered with lncRNA MEG3 or blank carrier. Evaluating the cell proliferation rate of difference groups by MTT assay; measuring the cell apoptosis and cell cycle of difference groups’ cell by flow-cytometry; the cell invasion activity of difference groups were measured by transwell assay, the cell migration ability of difference groups were evaluated by wound healing testing. Measuring the relative gene expressions (PI3K, AKT, MMP-2, MMP-9, Bcl-2, Bax and P21) and protein expressions (PI3K, AKT, p-AKT, MMP-2, MMP-9, Bcl-2, Bax and P21) by RT-PCR or WB assay.
Compared with NC group, The cell proliferation rate of lncRNA group was significantly reduced (P<0.05) and the cell apoptosis and G1 phase were significantly increased (P<0.05, respectively). The invasion cell of lncRNA MEG3 group were significantly difference compared with NC group (P<0.05), and the wound healing rate of lncRNA MEG3 group was significantly shorter than NC group (P<0.05). The PI3K, AKT, MMP-2, MMP-9 and Bcl-2 gene expression of lncRNA group were significanlty down-regulation compared with NC group (P<0.05,respectively), and Bax and P21 gene expression of lncRNA group were significantly up-regulation compared with NC group (P<0.05,respectively) by RT-PCR testing. The PI3K, AKT, p-AKT, MMP-2, MMP-9 and Bcl-2 protein expression of lncRNA group were significanlty down-regulation compared with NC group (P<0.05,respectively), and Bax and P21 protein expression of lncRNA group were significantly up-regulation compared with NC group (P<0.05,respectively) by WB assay.
The lncRNA MEG3 had effects to supress cervical cancer by regulation PI3K/AKT/Bcl-2/Bax/P21 and PI3K/AKT/MMP-2/9 signaling pathway.
Finite element simulations were conducted to investigate the dynamic responses of metallic sandwich spherical shells with graded aluminum foam cores under inner blast loading. The deformation of ...spherical shells, the energy absorption of each core layer, and the propagation characteristic of stress waves in the foam core layers were analyzed and discussed. The spherical shells exhibited an overall inflation–deformation mode as the foam cores were compressed gradually. The arrangement of the core layers with different relative densities had significant effects on the dynamic plastic responses of the spherical shells. The core layer arrangements of 15%–20%–10% and 20%–15%–10% (relative densities) from inside to outside demonstrate the optimal resistance to blast loading.
Land cover changes in tropical rainforest climate zones play an important role in global climate change and the functioning of the Earth’s natural system. Existing research on the consistency of ...different land cover products has mainly focused on administrative divisions (continental or national scales). However, the ongoing production of large regional or global land cover products with higher resolutions requires us to have a better grasp of confusing land types and their geographical locations for different zoning (e.g., geographical zoning) in order to guide the optimization of strategies such as zoning and sample selection in automated land cover classification. Therefore, we selected the GlobeLand30-2010, GLC_FCS30-2015, and FROM_GLC2015 global land cover products with a 30-m resolution covering Indonesia, which has a tropical rainforest climate, as a case study, and then analyzed these products in terms of areal consistency, spatial consistency, and accuracy evaluation. The results revealed that (a) all three land cover products revealed that forest is the main land cover type in Indonesia. The area correlation coefficient of any two products is better than 0.89; (b) the areas that are completely consistent among the three products account for 58% of the total area of Indonesia, mainly distributed in the central and northern parts of Kalimantan and Papua, which are dominated by forest land types. The spatial consistency of the three products is low, however, due to the complex surface types and staggered distributions of grassland, shrub, cultivated land, artificial surface, and other land cover types in Java, eastern Sumatra, and the eastern, southern, and northwestern sections of Kalimantan, where the elevation is less than 200 m. Given these results, land cover producers should take heed of the classification accuracy of these areas; (c) the absolute accuracy evaluation demonstrated that the GLC_FCS30-2015 product has the highest overall accuracy (65.59%), followed by the overall accuracy of the GlobeLand30-2010 product (61.65%), while the FROM_GLC2015 exhibits the lowest overall accuracy (57.71%). The mapping accuracy of the three products is higher for forests and artificial surfaces. The cropland mapping accuracy of the GLC_FCS30-2015 product is higher than those of the other two products. The mapping accuracy of all products is low for grassland, shrubland, bareland, and wetland. The classification accuracy of these land cover types requires further improvement and cannot be used directly by land cover users when conducting relevant research in tropical rainforest climate zones, since the utilization of these products could lead to serious errors.
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