Mechanical Analysis Research Articles

Mechanism Analysis and Elimination of Multiple Pulse Phenomenon of Active Rectifier in Wireless Power Transfer Systems

Mechanism Analysis and Elimination of Multiple Pulse Phenomenon of Active Rectifier in Wireless Power Transfer Systems

Multiscale Analysis of the Function Mechanism of Aging Action on the Adhesion Properties between Asphalt and Aggregate

Multiscale Analysis of the Function Mechanism of Aging Action on the Adhesion Properties between Asphalt and Aggregate

Analysis of Deformation Characteristics and Failure Mechanism of Interbedded Surrounding Rock Tunnels Based on Principal Stress Difference

Analysis of Deformation Characteristics and Failure Mechanism of Interbedded Surrounding Rock Tunnels Based on Principal Stress Difference

Analysis of Urban Thermal Environment Evolution and Mechanisms Based on Multisource Data: A Case Study of Hangzhou, China

Analysis of Urban Thermal Environment Evolution and Mechanisms Based on Multisource Data: A Case Study of Hangzhou, China

Trade networks and corporate ESG performance: Evidence from Chinese resource-based enterprises

Trade network connects enterprises together, while its impact on corporate ESG performance is unknown. Drawing on unbalanced panel data of resource-based enterprises in China from 2009 to 2021, this study decomposes the trade network into purchasing network and sales network based on trade directions, and explores their impact on corporate ESG performance and the mechanisms involved. The findings indicate that: (1) The trade networks exhibit a negative correlation with corporate ESG performance. Meanwhile, purchasing network demonstrates a more pronounced adverse impact on corporate ESG than sales network. After a series of endogeneity tests, the above results still hold. (2) Heterogeneity analysis shows that trade networks have a more significant effect on the ESG performance of state-owned enterprises, mature enterprises and heavily polluting enterprises. And the most pronounced negative effect is observed in the governance (G) component of ESG. (3) Mechanism analysis reveals that trade networks negatively influence corporate ESG performance by impeding the progress of green innovation and internal control. (4) Accelerating digital transformation and intensifying government environmental regulations can mitigate the inhibitory impact of trade networks on corporate ESG performance. This study provides theoretical support and empirical evidence for resource-based enterprises to enhance ESG performance while reinforcing trade linkages.

Failure mechanism analysis and support strength determination of deep coal mine roadways-A case study

In order to solve the problems related to deformations, failures, and difficulties in support controls of deep coal mine roadways, the typical failure forms and characteristics of deep coal mine roadways were investigated and analyzed in this study. The distribution laws of plastic zones of circular roadways under different lateral pressure coefficients were expounded using a theoretical analysis method, and the influence of plastic zone scopes on the failure forms of roadways was explained. In addition, considering the distribution characteristics of plastic zones, a calculation method of the required support strength based on the plastic zone scopes was proposed. The primary and secondary factors affecting the support strength were then determined. A numerical simulation method was applied in order to analyze the distribution characteristics of the displacements and plastic zones of deep mine circular roadways under the conditions of no support scheme, an existing support scheme, and a support scheme determined by the proposed support strength calculation method (referred to in this study as the optimized support scheme), respectively. The simulation results showed that the support effects of the optimized support scheme were superior to those of the existing support scheme, and thereby more conducive to maintaining roadway stability. In addition, an on-site engineering test method was used to identify support schemes for bolting and shotcrete with wire mesh + concrete-filled steel tubular supports based on the plastic zone scopes and the support strength of roadways in order to determine the support parameters. As indicated by the field monitoring results, the proposed support strength calculation method and optimized support scheme had shown the ability to effectively control the large deformations of the tested roadway, and thereby guarantee its overall stability.

Efficient separation of alcohol ester via extractive distillation and pressure swing distillation based on molecular interaction mechanism analysis

N-amyl alcohol, n-amyl formate, n-propanol and n-propyl formate are all organic solvents with important industrial application value. In industrial production, related alcohol ester azeotropic systems are often generated. Therefore, it is necessary to study the refining process of these substances. The work designed purification processes for two different azeotropic systems of alcohol esters via extractive distillation and pressure swing distillation methods. The required binary interaction parameters were obtained through vapor–liquid equilibrium experiments. Based on experimental data, a suitable entrainer was determined through different methods of analysis. The processes were optimized with the economic cost as the objective. In addition, it evaluated and analyzed different processes from multiple perspectives. This work explores the purification process of alcohol ester systems, providing theoretical guidance for achieving efficient separation of alcohol ester systems.

E-commerce and Rural Women Entrepreneurship ——Based on the Quasi-Natural Experiment of “Comprehensive Demonstration Policy” for E-commerce in Rural Areas

The importance of information and communication technology in rural areas has gradually become prominent, and rural e-commerce has emerged as a crucial driver for promoting agricultural and rural development. This paper takes the comprehensive demonstration policy for e-commerce in rural areas as a quasi-natural experiment. It is based on five-period panel data from the China Family Panel Studies (CFPS) and employs the staggered difference-in-differences method to examine the impact of e-commerce on rural women entrepreneurship and its mechanisms. The research results indicate that the implementation of the comprehensive demonstration policy for e-commerce in rural areas significantly increases the probability of rural women engaging in entrepreneurship by 1.6% points. The entrepreneurial promotion effect of this demonstration policy is more pronounced for rural women in the central and western regions and those with lower educational levels, demonstrating the inclusiveness of e-commerce in rural development. Additionally, this promotion effect is also significantly influenced by marital heterogeneity. Mechanism analysis results suggest that the comprehensive demonstration policy for e-commerce in rural areas can stimulate the use of information and communication technology by rural women, leverage the crucial role of non-traditional education in skill development, alleviate financial and social capital constraints for rural women, and inspire a wave of rural women entrepreneurship. The paper argues that the construction of rural e-commerce has the potential to empower rural women entrepreneurship.

Digital transformation of enterprises under the pressure of air pollution

ABSTRACT Although the effects of air pollution on economics have been reflected in recent research, very little literature has explored whether enterprises are actively adopting digital transformation under the pressure of air pollution. Considering the serious air pollution in China and the importance of digital transformation, this study uses the panel data of Chinese A-share listed companies and air quality data, from 2014 to 2020, to investigate the impact of air pollution pressure on digital transformation. The results show that air pollution pressure forces enterprises to engage in digital transformation. The conclusion still holds after endogeneity and robustness tests. Further, a mechanism analysis indicates that air pollution pressure affects digital transformation through green cognition, green innovation, and government subsidies. Meanwhile, regional informatization positively moderates the relationship between air pollution pressure and three mechanisms. Finally, a heterogeneity analysis shows that air pollution significantly affects digital transformation in eastern regions, state-owned, capital-intensive, and technology-intensive enterprises.

Photothermal Assisted Biomass Oxidation for Pairing Carbon Dioxide Electroreduction with Low Cell Potential.

Integrating anodic biomass valorization with carbon dioxide electroreduction (CO2RR) can produce value-added chemicals on both the cathode and anode; however, anodic oxidation still suffers from high overpotential. Herein, a photothermal-assisted method was developed to reduce the potential of 5-hydroxymethyl furfural (HMF) electrooxidation. Capitalizing on the copious oxygen vacancies, defective Co3O4 (D-Co3O4) exhibited a stronger photothermal effect, delivering a local temperature of 175.47 oC under near infrared light illumination. The photothermal assistance decreased the oxidation potential of HMF from 1.7 V over pristine Co3O4 to 1.37 V over D-Co3O4 to achieve a target current density of 30 mA cm-2, with 2,5-furandicarboxylic acid as the primary product. Mechanistic analysis disclosed that the photothermal effect did not change the HMF oxidation route but greatly enhanced the adsorption capacity of HMF. Meanwhile, faster electron transfer for direct HMF oxidation and the surface conversion to cobalt (oxy)hydroxide, which contributed to indirect HMF oxidation, was observed. Thus, rapid HMF conversion was realized, as evidenced by in situ surface-enhanced infrared spectroscopy. Upon coupling cathodic CO2RR with an atomically dispersed Ni-N/C catalyst, the Faradaic efficiencies of CO (cathode) and 2,5-furandicarboxylic acid (FDCA, anode) exceeded 90.0% under a low cell potential of 1.77 V.

Impact of the National Ecological Civilization Construction Demonstration Zone on corporate ESG: Evidence from China

This study examines the effect of implementation of the National Ecological Civilization Construction Demonstration Zone (NECCDZ) policy in China as a quasi-natural experiment on Chinese listed firms’ ESG performance. By utilizing a multi-period differences-in-differences model, the empirical results reveal that the NECCDZ policy boosted the ESG performance of China’s A-share listed companies in the pilot region by an average of 38%. However, the NECCDZ policy has differential effects on the three subdimensions of ESG. More specifically, the NECCDZ policy significantly improves the social responsibility performance and governance performance of the company, and has a lagged positive effect on the environmental performance. The mechanism analysis shows that the NECCDZ policy enhances corporate ESG practices by promoting enterprise green technology innovation, while media attention positively moderates the impact of the NECCDZ policy on corporate ESG practices. Further analysis shows that the NECCDZ policy also improves the enterprises’ financing environment through government subsidies and public investment. Overall, the empirical findings show the effectiveness of NECCDZ policy in enhancing ESG practices at the enterprise level and offer a new approach to improving corporate ESG finance in emerging markets such as China.

Designing the Second Target Station with a Coupled Neutronics-Mechanical Optimization Workflow

The Second Target Station (STS) at the Spallation Neutron Source of the U.S. Department of Energy’s Oak Ridge National Laboratory is being designed to become the world’s highest peak brightness source of cold neutrons. As the STS project evolves, neutronics and other engineering analyses will inform many design iterations. To facilitate this process, a fully automated optimization workflow was developed to convert a parameterized computer-aided-design model of the target into an unstructured mesh geometry model and then to run a neutronics calculation and (optionally) a mechanical analysis for each design iteration. This workflow enables efficient, high-fidelity modeling; simulation; and optimization of new designs, as has been demonstrated for the optimization of the STS neutron moderators. In this paper, we present the results of our first major effort to automate the design optimization process for a spallation target. In the first analysis, the goal is to find optimal dimensions of a monolithic tungsten target coupled with an optimal super-Gaussian proton beam profile to deliver maximum brightness of the resulting neutron beams while maintaining good mechanical properties of the target. In the second analysis, geometric and beam parameters are optimized for an alternative design with tungsten plates, which can reach superior mechanical performance without compromising the neutronics performance.

Syntaxin-6 delays prion protein fibril formation and prolongs presence of toxic aggregation intermediates.

Prions replicate via the autocatalytic conversion of cellular prion protein (PrPC) into fibrillar assemblies of misfolded PrP. While this process has been extensively studied in vivo and in vitro, non-physiological reaction conditions of fibril formation in vitro have precluded the identification and mechanistic analysis of cellular proteins, which may alter PrP self-assembly and prion replication. Here, we have developed a fibril formation assay for recombinant murine and human PrP (23-231) under near-native conditions (NAA) to study the effect of cellular proteins, which may be risk factors or potential therapeutic targets in prion disease. Genetic screening suggests that variants that increase syntaxin-6 expression in the brain (gene: STX6) are risk factors for sporadic Creutzfeldt-Jakob disease (CJD). Analysis of the protein in NAA revealed, counterintuitively, that syntaxin-6 is a potent inhibitor of PrP fibril formation. It significantly delayed the lag phase of fibril formation at highly sub-stoichiometric molar ratios. However, when assessing toxicity of different aggregation time points to primary neurons, syntaxin-6 prolonged the presence of neurotoxic PrP species. Electron microscopy and super-resolution fluorescence microscopy revealed that, instead of highly ordered fibrils, in the presence of syntaxin-6 PrP formed less-ordered aggregates containing syntaxin-6. These data strongly suggest that the protein can directly alter the initial phase of PrP self-assembly and, uniquely, can act as an 'anti-chaperone', which promotes toxic aggregation intermediates by inhibiting fibril formation.

Accelerated Proton Transfer in Asymmetric Active Units for Sustainable Acidic Oxygen Evolution Reaction.

The poor durability of Ru-based catalysts limits the practical application in proton exchange membrane water electrolysis (PEMWE). Here, we report that the asymmetric active units in Ru1-xMxO2 (M = Sb, In, and Sn) binary solid solution oxides are constructed by introducing acid-resistant p-block metal sites, breaking the activity and stability limitations of RuO2 in acidic oxygen evolution reaction (OER). Constructing highly asymmetric Ru-O-Sb units with a strong electron delocalization effect significantly shortens the spatial distance between Ru and Sb sites, improving the bonding strength of the overall structure. The unique two-electron redox couples at Sb sites in asymmetric active units trigger additional chemical steps at different OER stages, facilitating continuous proton transfer. The optimized Ru0.8Sb0.2O2 solid solution requires a superlow overpotential of 160 mV at 10 mA cm-2 and a record-breaking stability of 1100 h in an acidic electrolyte. Notably, the scale-prepared Ru0.8Sb0.2O2 achieves efficient PEMWE performance under industrial conditions. General mechanism analysis shows that the enhanced proton transport in the asymmetric Ru-O-M unit provides a new working pathway for acidic OER, breaking the scaling relationship without sacrificing stability.

Multi-objective optimization, shrinkage and fracture properties of unsaturated polyester resin modified concrete for bridge deck pavement based on system theory

For the purpose of fabricating unsaturated polyester modified concrete (UPMC) with excellent shrinkage and fracture properties for bridge deck pavement, the optimization design of mix proportion and enhancement mechanism analysis were implemented based on system theory. Firstly, for unsaturated polyester resin (UPR) subsystem, the viscosity, mechanical properties and droplet-size distribution were analyzed to determine the types and dosage of auxiliary additives after emulsification treatment; Next, for UPMC mortar slave-system, the optimization design was implemented through the combination of experimental analysis and hybrid multi-attribute ellipsoidal decision of grey-target (HMEDG) model; Subsequently, for UPMC main-system, the optimal proportion was determined utilizing orthogonal design test. Finally, the variation law and enhancement mechanism on fracture properties and shrinkage characteristics of UPMC was analyzed by combining macroscopic test, thermogravimetry (TG) and X-ray diffraction (XRD). The results demonstrated that 2.0 wt%BPO+1.0 wt%DMA and meta-benzene types UPR were utilized as auxiliary additives for UPMC based on the results of HMEDG models. The demulsified and cured WUP might supplement the interior moisture losses based on humidity compensation, and substantially constrain the evaporation loss inside the matrix, upgrading the hydration degree and facilitating the generation of hydration products. The introduction of 3 %-6 % waterborne-UPR (WUP) would improve 28d-fracture toughness within approximately 23.33 %-49.32 %, and reduce the shrinkage deformation by roughly 28–43 % through inducing the crack tip stress redistribution against the initiation and propagation of interior microcracks and enhancing the homogenization and densification.

Mechanism Analysis of the Reduction Process of the NiO-YSZ Anode of a Solid Oxide Fuel Cell by Hydrogen

Abstract Reduction of the nickel oxide-yttria stabilized zirconia (NiO-YSZ) anode is a significant step before the operation of a solid oxide fuel cell (SOFC). However, phenomena which occur during the reduction and their mechanism analyses are not summarized sufficiently. In this study, we investigated the influence of the hydrogen concentration, water vapor concentration of the reduction gas, Y2O3 content of the YSZ material of the anode, and temperature on the reduction process. The results showed that water vapor added to the hydrogen during reduction caused a temporary stasis period of the open circuit voltage. The length of the temporary stasis period was almost irrelevant to the water vapor concentration. During reduction, the length of the temporary stasis period of the open circuit voltage was negatively associated with hydrogen concentration and temperature, but positively associated with Y2O3 content of the YSZ material of the anode. After reduction, the SOFC showed better initial performance when the hydrogen concentration or the water vapor concentration during the reduction were higher. The classical shrinking core model can be used to explain these phenomena.

Impact and mechanism analysis of industrial robot imports on export performance of Chinese firms

Digital import trade is of great practical significance for enhancing the export performance of enterprises and preventing external shocks. This paper empirically examines the impact and mechanism of industrial robot imports on Chinese firms’ export performance based on Chinese microenterprise data from 2004 to 2014. The study shows that the application of imported robots can significantly improve firms’ export performance, and this conclusion still holds after a series of robustness tests. Heterogeneity analysis shows that imported robots have a more significant role in boosting the export performance of state-owned enterprises and enterprises in capital- and technology-intensive industries; at the same time, they have a significant effect on the export performance of enterprises in different modes of trade; and they have a significant role in boosting the export performance of enterprises in eastern China compared with those in central and western regions. Mechanism analysis shows that the enhancement of export performance of enterprises by imported robots is mainly realized by promoting enterprise productivity and human capital efficiency. The policy implication of this paper is that in the era of digital trade, Chinese enterprises should fully utilize the import of digital products to enhance their productivity and promote the high-quality development of foreign trade.

Environmental Protection Tax Reform in China: A Catalyst or a Barrier to Total Factor Productivity? An Analysis through a Quasi-Natural Experiment

China’s 2018 environmental protection tax (EPT) reform was introduced in response to increasing concerns about environmental degradation. It aimed to use fiscal policy to enhance environmental governance while fostering economic productivity. This study employs a difference-in-differences approach to analyze panel data from publicly listed companies between 2009 and 2019. It examines the reform’s influence on total factor productivity (TFP) in pollution-intensive industries, addressing both environmental and economic objectives. The results reveal that the tax reform significantly enhances TFP, acting as a robust catalyst for economic growth rather than a barrier. This effect is particularly strong in state-owned enterprises and those with less-severe financing constraints. Mechanism analysis indicates that the reform boosts TFP through the promotion of green innovations and alleviation of financing constraints. These findings provide empirical evidence at the micro-level of the reform’s efficacy in promoting sustainable business practices. The study offers insights for future environmental tax policies in China and underscores the necessity of aligning environmental and economic strategies to achieve sustainable development.

Analysis of the Molecular Mechanism of Energy Metabolism in the Sex Differentiation of Chickens Based on Transcriptome Sequencing

The determination of sex in mammals is established and controlled by various complex mechanisms. In contrast, sex control in poultry remains an unresolved issue. In this study, RNA-sequencing was conducted for male gonads and ovarian tissues in chicken embryos of up to 18.5 days to identify metabolic factors influencing male and female sex differentiation, as well as gonadal development. Our results reveal that PKM2, a critical glycolysis-related protein, plays a significant role in chicken sex differentiation via PPARG, a crucial hormone gene. We propose that our discoveries bolster the notion that glycolysis and oxidative phosphorylation function as antecedent contributors to sexual phenotypic development and preservation.

Research on the static and dynamic tensile damage mechanism of concrete based on fuzzy sets

The quantitative analysis of microscopic damage mechanisms in concrete and the formulation of damage evolution equations using mathematical theory and computerized tomography (CT) imaging are still emerging fields. The test data from CT scans have yet to be fully exploited. This study proposes a method for quantitatively characterizing mesoscale damage evolution in concrete. By segmenting CT images from static and dynamic tensile tests, we define metrics such as the aggregate rate, mortar rate, and porosity to examine the damage progression under both stress conditions. We then establish a damage evolution model based on porosity changes. Our findings reveal that crack growth in concrete is slower under static tension, with cracks navigating around aggregates towards weaker regions. Conversely, under dynamic loads, cracks propagate more rapidly and directly through aggregates, following paths of quicker energy dispersion. Static loading results in less aggregate damage than does dynamic loading, with a notable increase in porosity and a more varied change in the mortar rate. The damage to the finer components of concrete increases as the crack-adjacent region diminishes. Damage is generally more extensive under static loading than under dynamic loading. The proposed porosity-based damage evolution model effectively describes concrete damage under static tension, leveraging CT technology to enhance the universality of the research and offering a microscopic-level theoretical foundation for studying concrete mechanical properties.