Human Body Model for Channel Characterization Based on Ray-Tracing

The propagation channel around human body will fluctuate due to the body effects, so it is essential to investigate the body channel. As an important method of channel modeling, ray-tracing (RT) is affected by the human body model. In this paper, a realistic human body is modeled with the idea of greedy algorithm. Based on the RT simulation and measurement results of path loss (PL), we derive the approximate shapes of the torso, head, arms, and legs, and propose a reference human body model whose credibility and accuracy have been verified at 2.4 GHz and 60 GHz. These results prove that the simulation results based on the reference human body model are in good agreement with the measurement values. In addition, the reference human body model can be adjusted according to the realistic dimension data of body

Vehicle-to-Vehicle Channel Characterization Based on Ray-Tracing for Urban Road Scenarios

In this paper, the vehicle-to-vehicle (V2V) channel characteristics in peak hours at the 5.9 GHz band in two typical urban road scenarios, the urban straight road and the intersection, are investigated. The channel characteristics, such as path loss, root mean square (RMS) delay spread, and angular spread, are derived from the ray-tracing (RT) simulations. Due to the low height of antennas at both the transmitter (Tx) and the receiver (Rx), the line of sight (LOS) between the Tx and the Rx will often be obstructed by other vehicles. Based on the RT simulation results, the shadowing loss is modelled by the multimodal Gaussian distribution, and path loss models in both LOS and non-LOS (NLOS) conditions are obtained. And the RMS delay spread in two scenarios can be modelled by the Weibull distribution. In addition, the deployment of an antenna array is discussed based on the statistics distribution of the angular spread

Corrosion and mechanical properties of AM50 magnesium alloy after modified by different amounts of rare earth element Gadolinium

To improve the corrosion and mechanical properties of the AM50 magnesium alloy, different amounts of the rare earth element gadolinium were used. The microstructure, corrosion and mechanical properties were evaluated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and electrochemical and mechanical stretch methods. The results indicate that, with Gd addition, the amount of the Al2Gd3 phase increased while the β-Mg17Al12 phase amount decreased. Due to the Gd addition, the grain of the AM50 magnesium alloy was significantly refined, which improved its tensile strength. Further, the decrease in the amount of the β phase improved the corrosion resistance of the alloy. The fracture mechanism of the Gd-modified AM50 magnesium alloy was a quasi-cleavage fracture. Finally, the optimum corrosion residual strength of the AM50 magnesium alloy occurred with 1 wt.%of added Gd

Stress Corrosion Behavior of AM50Gd Magnesium Alloy in Different Environments

A new type of high strength corrosion-resistant magnesium alloy was prepared by adding 1% rare earth Gd to AM50 and then treated with hot extrusion method. The stress corrosion properties of the new materials in air, pure water, 0.5 mol/L NaCl, and 0.5 mol/L Na2SO4 solution were studied by the slow strain rate tensile (SSRT) test, in situ open circuit potential test, Tafel curve test, stereomicroscope, SEM, and EDS. The results showed the following. The stress corrosion sensitivity of the material in different environments was Na2SO4 > NaCl > distilled water > air. According to the Tafel curves measured at 0 and 100 MPa, the corrosion voltage decreased little and the corrosion current density increased rapidly under 100 Pa. This was because the film of the corrosion product ruptured to form a large cathode and a small anode, which resulted in a large instantaneous corrosion current. The mechanism of hydrogen embrittlement and anodic dissolution together affected the stress corrosion behavior of the alloy. In distilled water, hydrogen embrittlement played a major role, while in NaCl and Na2SO4 solution, hydrogen embrittlement and anodic dissolution were both affected. The direct reason of the stress corrosion crack (SCC) samples’ failure was the cracks expanding rapidly at the bottom of pit, which was caused by corrosion

Effect of Adding Rare Earth Elements Er and Gd on the Corrosion Residual Strength of Magnesium Alloy

The effects of the single and compound addition of rare earth Gd and Er on corrosion resistance and residual strength of as-cast AM50 magnesium alloy were studied using XRD, SEM, EDS, the weightlessness test, electrochemistry method, and tensile test. The results of XRD and SEM showed that Al3Er, Al2Gd3, and Al–Mn–Gd(Er) phases appeared in the alloy structure after the addition of rare earth Er and Gd. The results from the weightlessness test and Tafel curves show that the corrosion resistance of the modified composite rare earth was improved. Stress concentration caused by a corrosion pit is the direct cause of the tensile samples after corrosion. The corrosion residual strength of modified composite rare earth specimens is better than that of modified single rare earth samples. Fracture analysis indicates that the addition of rare earth elements did not change the fracture mechanism of the alloy, and the fracture was still the cleavage fracture

Facile Synthesis of Diatomite/β-Cyclodextrin Composite and Application for the Adsorption of Diphenolic Acid from Wastewater

Diphenolic acid (DPA) is a kind of endocrine-disrupting compound, which brings serious health problems to humans and animals. An eco-friendly and cost-effective adsorbent was prepared through a simple method, in which the β-Cyclodextrin(β-CD) was crosslinked onto the surface of diatomite (DA), the as-prepared DA/β-CD composite showed higher adsorption efficiency for DPA than DA as the host–guest interaction between DPA and β-CD. DA is a kind of biosilica with a hierarchical pore structure that provides enough surface area for the DA/β-CD. The surface area and pore size of DA/β-CD were investigated by nitrogen adsorption and desorption. The DA/β-CD composite illustrated a good adsorption capability, and was used for removing DPA from wastewater. The adsorption ratio of DPA could achieve 38% with an adsorption amount of 9.6 mg g−1 under room temperature at pH = 6. The adsorption isotherm curves followed the Langmuir (R2 = 0.9867) and Freundlich (R2 = 0.9748) models. In addition, the regeneration rate of the DA/β-CD was nearly at 80.32% after three cycles of regeneration. These results indicated that the DA/β-CD has the potential for practical removal of the EDC contaminants from wastewater

A Positive Association between Working Memory Capacity and Human Creativity: A Meta-Analytic Evidence

Creativity serves as a fountain for social and scientific development. As one of the most crucial human capabilities, creativity has been believed to be supported by the core component of higher cognitive functions—working memory capacity (WMC). However, the evidence supporting the association between WMC and creativity remains contradictory. Here, we conducted a meta-analysis using random-effects models to investigate the linear association between WMC and creativity by pooling the individual effect size from the previous literature. Further, a subgroup analysis was performed to examine whether such association is specific for different WMC categories (i.e., verbal WMC, visual–spatial WMC and dual-task WMC). The main meta-analytic results showed a significantly positive association between WMC and creativity (r = .083, 95% CI: .050–.115, p < .001, n = 3104, k = 28). The subgroup analysis demonstrated consistent results by showing a significantly positive association between them, irrespective of WMC category. We also found that cultural environments could moderate this association, and we identified a strong correlation in participants from an Asian cultural context. In conclusion, this study provides the evidence to clarify the positive association between WMC and creativity, and implies that the Asian cultural context may boost such an association

Attitude and Performance for Online Learning during COVID-19 Pandemic: A Meta-Analytic Evidence

The COVID-19 pandemic prominently hit almost all the aspects of our life, especially in routine education. For public health security, online learning has to be enforced to replace classroom learning. Thus, it is a priority to clarify how these changes impacted students. We built a random-effect model of a meta-analysis to pool individual effect sizes for published articles concerning the attitudes and performance towards online learning. Databases included Google Scholar, PubMed and (Chinese) CNKI repository. Further, a moderated analysis and meta-regression were further used to clarify potential heterogenous factors impacting this pooled effect. Forty published papers (n = 98,558) were screened that were eligible for formal analysis. Meta-analytic results demonstrated that 13.3% (95% CI: 10.0&ndash;17.5) of students possessed negative attitudes towards online learning during the COVID-19 pandemic. A total of 12.7% (95% CI: 9.6&ndash;16.8) students were found to report poor performance in online learning. Moderated analysis revealed poor performance in online learning in the early pandemic (p = 0.006). Results for the meta-regression analysis showed that negative attitudes could predict poor learning performance significantly (p = 0.026). In conclusion, online learning that is caused by COVID-19 pandemic may have brought about negative learning attitudes and poorer learning performance compared to classroom learning, especially in the early pandemic

Study on the Mechanism of Lianpu Drink for the Treatment of Chronic Gastritis Based on Network Pharmacology

Chronic gastritis (CG) places a considerable burden on the healthcare system worldwide. Traditional Chinese Medicine (TCM) formulas characterized by multicompounds and multitargets have been acknowledged with striking effects in the treatment of CG in China’s history. Nevertheless, their accurate mechanisms of action are still ambiguous. In this study, we analyzed the effective compounds, potential targets, and related biological pathway of Lianpu Drink (LPD), a TCM formula which has been reported to have a therapeutic effect on CG, by contrasting a “compound-target-disease” network. According to the results, 92 compounds and 5762 putative targets of LPD were screened; among them, 8 compounds derived from different herbs in LPD and 30 common targets related to LPD and CG were selected as candidate compounds and precision targets, respectively. Meanwhile, the predicted common targets were verified by Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analysis and pharmacological experiments. The results demonstrated that quercetin, ephedrine, trigonelline, crocetin, and β-sitosterol were major effective compounds of LPD responsible for the CG treatment by inhibiting the activation of the JAK 2-STAT 3 signaling pathway to reduce the expressions of cyclin D1 and Bcl-2 proteins. The study provides evidence for the mechanism of understanding of LPD for the treatment of CG

A Hydrochemical Study of Groundwater Salinization in Qinzhou Bay, Guangxi, Southern China

Abstract The salinity of groundwater in Qinzhou Bay has been increasing since 2013. This phenomenon affects livelihoods and the local agricultural economy, specifically in the Longmengang area. In this work, we investigate the causes of water salinization to provide evidence for effectively managing the local water resources and improving water quality. We collected 110 samples of water from spatially distributed local wells, rivers, reservoirs, and the sea, and conducted a hydrochemical study complemented by numerical modeling. We found that water pumping and mariculture practices are the principal contributors to seawater intrusion into the groundwater table, which leads to increased water salinization