Mechanical Analysis Research Articles

ZIF-8-derived N-doped porous carbon electrodes enabled with in situ embedded ZrO2 nanoparticles for phosphorus removal

Excessive phosphorus discharges are not favorable to the normal functioning of water ecosystems. Although some treatments have been implemented to control phosphorus concentrations in sewage, several challenges remain for them. Capacitive deionization technology (CDI) possesses excellent potential for phosphorus removal, and the electrode material is the key to CDI. Herein, a novel ZIF-8-derived N-doped porous carbon electrode enabled with in situ embedded ZrO2 nanoparticles (ZNPC) was fabricated through a simple in-situ growth approach. The experimental results demonstrate that ZrO2 embedded in ZNPC can improve the electrochemical performance and provide suitable affinity sites for phosphorus, thus enhancing the electrode performance in capturing phosphorus. Isothermal and kinetic models were adopted to investigate the phosphorus uptake process. Mechanism analysis reveals that the phosphorus removal behavior is associated with the electric field, ligand exchange, and electrostatic attraction. This study provides a promising approach for facile constructing Zr-based N-doped porous carbon and expands its potential utility for phosphorus removal from aqueous solutions.

Fused granulate fabrication of injection molding inserts from high-performance ULTEM 9085™ thermoplastic for cosmetic packaging industry

AbstractRTIM refers to the integration of rapid tooling (RT) using additive manufacturing (AM) with injection molding (IM). Due to the use of raw material (pellet), screw extrusion, fused granulate fabrication (FGF) allows for a cost-effective and versatile production of RTIM inserts especially compared to other material extrusion (MEX) AM processes, such as fused filament fabrication (FFF). This study 3D printed RTIM inserts out of high-performance thermoplastic polyetherimide (PEI) (ULTEM 9085) in granular form, using an in-house developed FGF system. A cosmetic compact was used as a case study part with a simplified design. A dynamic mechanical analysis (DMA) conducted on FGF ULTEM 9085 demonstrated that the strength of the inserts is sustained up to 140 °C, which suits injection molding using polypropylene (PP). Optical profilometry of the FGF 3D printed RTIM inserts demonstrated that when using a 0.4 mm nozzle, the flat surfaces produced had microscopic gaps larger than 10–1 mm. These gaps are sufficiently large so that melt of low viscosity polymer is able to flow through, which leads to undesired part flash. The IM experiments confirmed that the inserts were capable of producing PP parts but with the predicted flash. Simulated part deflection differed both on geometry and magnitude from the actual deflection measured by optical profilometry. A total of 36 prototype parts were produced before the inserts failed due to poor inter-layer bond strength. FGF RTIM using ULTEM 9085 is deemed suitable for prototype part production. Improving the inter-layer bond strength and decreasing part complexity could increase the number of parts produced.

Experimental study on Corn Straw Fiber (CSF) toughening EPS concrete

The natural Corn Straw Fiber (CSF), it has the advantages of light weight, high strength, good toughness and renewable, can delay the cracking and improve the toughness of cement-based materials. The effects of different mass fractions of CSF and Expanded-Polystyrene (EPS) particles on the compressive strength, flexural strength, splitting tensile strength and their failure modes, load-displacement curves and toughness of EPS concrete were analyzed by full factorial experimental design method. The compressive toughness index (I0, I1) and fracture energy (Gf) were defined to evaluate the effect of CSF on toughening EPS concrete. The results show that the addition of CSF can improve the compressive strength, flexural strength and cracking toughness of EPS concrete to a certain extent. The maximum compressive strength occurred in the E1F3 specimen with a CSF content of 3 % in Group I, which was 1.12 MPa, and the improvement rate was also the highest among the four groups, reaching 69.7 %. The compressive toughness index I1 also reached its maximum in the E1F3 specimen; The maximum flexural strength occurred in the E3F4 specimen with a 4 % CSF content in Group III, which was 0.885Mpa, with the highest improvement rate of 127.38 %. The maximum fracture energy Gf reached 0.827 in the E3F4 specimen. However, another additive, EPS particles, did not significantly improve the physical and mechanical properties of concrete. According to the SEM images and toughening mechanism analysis, it was discovered that tight adhesion between EPS particles and CSF with cement matrix, and the failure mode of CSF was tensile fracture, which could maximize the effect of CSF high tensile toughness. On the basis of mechanical properties and toughening effect, the relationship formulas between variable factors and strength, toughness index were fitted, and the optimal content of EPS and CSF were determined to be 1.3 % and 3 %, respectively.

Ultimate water level and deformation failures of the artificial dam in the coal mine underground reservoir

Coal mine underground reservoirs provide a new choice for the protection and utilization of water resources. This paper takes the underground reservoir of Wulanmulun Mine as the background, and takes the MB-1# artificial dam in the goaf of 31104–31116 working face of 3–1 coal seam as the research object. The theoretical model of artificial dam is established by elastic–plastic two-way slab theory, and the theoretical mechanical analysis and calculation are carried out. A similitude physical model for the coal mine underground reservoir was built by using the self-developed nested dual-dynamic-pressure similitude simulation testing system. Later, the mechanical response and deformation failure features of the artificial dam under different water pressure values were analyzed and the ultimate water pressure was determined. In addition, FLAC3D was used to determine the stress-seepage field-coupling model for the artificial dam. Using this model, the influence of water pressure on the multi-load coupling effect of the artificial dam and coal pillar dam was characterized. The dam form is optimized and the safety water level evaluation method of the dam body is proposed. The research results are as follows: (1) Based on the theory of elastic–plastic two-way slab, the theoretical analysis model of artificial dam is established, the expression of the ultimate water level function of artificial dam is derived, and the theoretical ultimate water head is determined to be 18.2 m (2) The seepage law of underground reservoir under different water pressures is obtained, and the ultimate water pressure of the model is determined to be 11.43 kPa. (3) It is clarified that the failure modes of the artificial dam are seepage failure and mechanical failure, and it is revealed that the groove area is the weakest position where the dam is most vulnerable to failure. In view of the failure modes of the dam, the I-shaped structure artificial dam is proposed. (4) A safe water level assessment method is proposed for the constructed artificial dam. According to the analysis of on-site monitoring data of MB-1# dam, the actual water level in the reservoir is within the allowable water level range of the artificial dam, and the whole reservoir is in a stable and relatively safe state at present. The reliability of this assessment method has been verified.

ESG Performance, Heterogeneous Creditors, and Bond Financing Costs: Firm-Level Evidence

Exploiting credit spread to measure firm bond financing costs, this study explored the impact of environmental, social, and governance (ESG) performance on bond financing costs from the perspective of heterogeneous creditors. Our results revealed that national interbank bond market and qualified institutional investors are increasingly interested in aligning their capital with ESG-related investment opportunities. Thus, they require a low rate of return from firms with good ESG performance. In contrast, domestic legal and natural persons and ordinary institutional investors are unlikely to accept a low investment return in exchange for the positive impact of ESG. Additional robustness tests confirmed the results, including firm-fixed effects, variable substitution method, supplemental variable method, lagged variable approach, instrumental variable analysis, and propensity score matching. The results of mechanism analysis indicated that the bond cost reduction effect of ESG is achieved by improving firms’ information disclosure quality and reputation. In addition, because of trade-off theory and agency problems, the environmental and social factors of ESG have only a limited impact on bond cost reduction, whereas the governance factor markedly reduces bond costs.

Optimized Design and Electromagnetic-Thermal- Mechanical Analysis of a Toroidal D-Shaped Superconducting Magnet in 5 MW LIQHY-SMES System

Optimized Design and Electromagnetic-Thermal- Mechanical Analysis of a Toroidal D-Shaped Superconducting Magnet in 5 MW LIQHY-SMES System

Morphology evolution and non-uniformity removal mechanism analysis of diamond nanocone arrays by reactive ion etching

By etching diamond films, microstructures can be fabricated on the surfaces, giving films with extra functionalities. During the etching process, the evolution of diamond surface morphology will affect the electric field near the microstructure. These changes in the electric field will alter the trajectory of ions, thereby affecting the number of ion bombardments on the surface regions of the microstructure. Consequently, this will affect the removal rate of the material on the microstructure surface and consequently affects the evolution of microstructure morphology. In order to understand the morphology evolution process of diamond during etching. H2 and Ar were used as the reactive gases to etch the nanocrystalline diamond (NCD) films with masks. The electric field near the microstructure and the trajectories of reactive ions was stimulated. The number of H+ and Ar+ bombardments at various regions on the diamond microstructure surface has been recorded and analyzed. By observing the cross-sectional morphology of the microstructure at different periods, the etching process of nanocones was analyzed. The study found that the microstructure of the diamond surface would gradually be etched into convex shaped and waist drum shaped and cone. By stimulating the electric field near the microstructure, it was found that the electric field distorted near the microstructure, causing the electric field lines initially perpendicular to the diamond surface to be diverted. As a result, the trajectory of the particles originally arrived perpendicularly to the diamond surface was distorted and hence they bombarded against the sidewall of the diamond microstructures. The angle between the ion trajectory and the electric field line also increased gradually.

Experimental Study on the Bond-Slip Behavior of Steel Tube-Coal Gangue Concrete

This study investigated the the bond-slip behavior at the interface between steel tubes and coal gangue concrete, considering the coal gangue coarse aggregate replacement rate, the strength grade of coal gangue concrete, and the bond length as variable parameters. Eleven groups of push out tests were conducted on steel tube coal gangue concrete specimens. The the bond slip curve and the longitudinal strain distribution curve of the steel tubes were obtained, and the effects of these parameters on bond strength were analyzed. The results showed that the load-slip curves at both the loading and free ends of the specimens were similar, with slip occurring earlier at the loading end. The regularity of the test curves in repeated experiments indicated that interfacial bond stress was primarily determined by friction in the later stages. The longitudinal strain of steel tubes was approximately exponentially distributed along their length. The interfacial bond strength increased with the increase of coal gangue aggregate replacement rate and was more pronounced in specimens with higher strength coal gangue concrete. Longer bond lengths resulted in greater bond failure loads, with a lower rate of increase in higher strength coal gangue concrete specimens compared to those with lower strength. Based on the three stage bond stress-slip relationship for steel tube-concrete, a bond-slip constitutive model for steel tube-coal gangue concrete was established. This provided a reference for mechanical analysis and interface performance design of steel tube-coal gangue concrete.

Optimization and mechanism analysis of photosynthetic EPA production in Nannochloropsis salina: evaluating the effect of temperature and nitrogen concentrations

Microalgae, recognized as sustainable and eco-friendly photosynthetic microorganisms, play a pivotal role in converting CO2 into value-added products. Among these, Nannochloropsis salina (Microchloropsis salina) stands out, particularly for its ability to produce eicosapentaenoic acid (EPA), a crucial omega-3 fatty acid with significant health benefits such as anti-inflammatory properties and cardiovascular health promotion. This study focused on optimizing the cultivation conditions of Nannochloropsis salina to maximize EPA production. We thoroughly investigated the effects of varying temperatures and nitrogen (NaNO3) concentrations on biomass, total lipid content, and EPA proportions. We successfully identified optimal conditions at an initial NaNO3 concentration of 1.28 g.L-1 and a temperature of 21°C. This condition was further validated by response surface methodology, which resulted in the highest EPA productivity reported in batch systems (14.4 mg.L-1.day-1). Quantitative real-time PCR and transcriptomic analysis also demonstrated a positive correlation between specific gene expressions and enhanced EPA production. Through a comprehensive lipid analysis and photosynthetic pigment analysis, we deduced that the production of EPA in Nannochloropsis salina seemed to be produced by the remodeling of chloroplast membrane lipids. These findings provide crucial insights into how temperature and nutrient availability influence fatty acid composition in N. salina, offering valuable guidance for developing strategies to improve EPA production in various microalgae species.

Fabrication of in situ polymerized polyaniline‐based functional nanofibrous structures for flexible electromechanical devices

AbstractRecently, flexible electromechanical devices (EMDs) emerged as alternatives to rigid electronics, promoting polymeric materials over traditional semiconductors. This study develops EMDs using conductive nanofibrous membranes of thermoplastic polyurethane (TPU), polyaniline (PANI), and multi‐walled carbon nanotubes (MWCNTs) in various structures. The fabrication technique included the combination of electrospinning and in situ polymerization to create random and aligned conductive membranes. Morphological, mechanical, thermomechanical, and electrical characterizations were conducted to assess their potential in EMDs applications. Mechanical testing revealed that, in comparison to aligned pure TPU mats, aligned TPU/PANI and TPU/MWCNTs/PANI membranes exhibited maximum strains of 26% and 19%, respectively. Meanwhile, randomly oriented mats, TPU/PANI and TPU/MWCNTs/PANI demonstrated maximum strains of 18% and 27%, respectively. Moreover, incorporating PANI and/or MWCNTs increased the Young's modulus. Thermogravimetric analysis showed thermal stability up to 250°C for all mats, with TPU/PANI mats demonstrating superior stability. Dynamic mechanical analysis revealed that PANI incorporation increased the storage modulus from 119 and 180 MPa to 2012 and 1367 MPa for aligned and random mats, respectively, compared with pure TPU mats. The combination of MWCNTs and PANI yielded moduli of 1501 and 1096 MPa, respectively. All conductive mats exhibited symmetric ohmic behavior, with conductivities varying based on orientation and composition. Specifically, TPU/PANI and TPU/MWCNTs/PANI mats exhibited conductivities of 0.83 and 1.78 S/cm for aligned mats, and 0.35 and 0.67 S/cm for random mats, respectively. Pure TPU, on the other hand, displayed a conductivity of 1.8 × 10−10 S/cm, indicating a significantly lower conductivity compared with the other mats.

The role of information industry convergence in energy transition

To cope with global climate risks, promoting energy transformation has become a global consensus. China issued a reform policy in 2010 to promote the convergence of the three major information industries, namely broadcasting and television networks, telecommunications networks and the Internet (TPR policy). However, is the convergence of information industries able to promote energy transition? This study constructs a quasi-natural experimental framework using China's TPR policy as a representative case of industrial convergence. Using city-level panel data between 2003 and 2016 in China and a multi-period difference-in-differences model, this study examines the impact of TPR policy on energy transition. The results show that TPR policy positively contributes to energy transition at a 1% significance level. Extensive robustness tests support this finding. This positive effect is particularly evident in regions with less developed communications infrastructure and stricter environmental regulations. Mechanism analysis suggests that TPR policy promotes energy transition by improving the level of information networks, promoting technological innovation, and optimizing industrial structure. The findings of this paper emphasize the importance of information industry convergence in facilitating energy transformation.

Facile purification of glass fiber powder by sedimentation for enhanced epoxy resin composites

Glass fiber powder contains two distinct forms: crumb-shaped and rod-shaped glass fiber powder particles. The shape and size of the particles in glass fiber powder have a great influence on its application. In order to separate rod-shaped glass fiber, the effects of different dispersants, such as SHMP, NaOL, and Na2SiO3 on them were investigated by settling experiments. Zeta potential, X-ray photoelectron spectroscopy (XPS), optical microscope, and other methods were used to analyze the adsorption behavior and settling mechanism. Three-point bending experiment and dynamic mechanical analysis (DMA) were used to evaluate the performance of epoxy resin composites reinforced with the raw glass fiber powder and the rod-shaped glass fiber powder. The results show that SHMP can effectively separate crumb-shaped glass fiber powder and rod-shaped glass fiber powder, leading to a notable increase in sedimentation recovery difference, up to Δ=51.08%. A preferential sedimentation separation mechanism is proposed to elucidate the settling mechanism. When the content of glass fiber powder and rod-shaped glass fiber is 5%, the glass transition temperature shifts significantly towards higher values, leading to the optimum comprehensive mechanical properties of the composites. Compared with the original epoxy resin, the flexural strength increased by 10.38% to 95.18MPa and by 20.11% to 103.57MPa. Similarly, the storage modulus increased by 14.14% to 2083MPa and by 21.64% to 2220MPa.

Performance evolution of epoxy adhesive and CFRP-steel epoxy-bonded joints subjected to hygrothermal exposure

Carbon fiber-reinforced polymer (CFRP)-steel epoxy-bonded joints are widely used in civil, mechanical, and railway engineering structures. However, the mechanical and bonding performance of the epoxy adhesive is sensitive to hygrothermal exposure, which may lead to performance degradation of CFRP-steel bonded interfaces. In this study, the performance evolution of epoxy adhesives and CFRP-steel epoxy-bonded joints after hygrothermal exposure was investigated. Three temperature levels (25°C/50°C/75°C) and three hygrothermal exposure time levels (24h/120h/360h) were considered. The dynamic mechanical behavior and tensile properties of the bulk adhesives were studied by dynamic mechanical analysis (DMA) and tensile tests, respectively. Additionally, the mechanical failure properties of the bonded joints, including failure mode, strain distribution, and bond-slip relationship were obtained by tensile tests. The results indicated that the glass transition temperature (GTT) and tensile strength of adhesive J133 are always higher than those of A2014 in all test scenarios. The interface remains the weakest after hygrothermal exposure. After the 50°C hygrothermal exposure, both CFRP-steel joints possess the highest bond strength and interfacial maximum bond stress, which corresponds to their higher adhesive tensile strength at the same temperature. In addition, we also find that both CFRP-steel joints show an increase in bond strength after short-term hygrothermal exposure.

Digital economy, data resources and enterprise green technology innovation: Evidence from A-listed Chinese Firms

The digital economy provides a framework for leveraging data resources to enhance enterprise green technology innovation. By harnessing digital tools and analytics, businesses can optimize resource use, streamline operations, and develop eco-friendly products and services. This synergy between the digital economy, data resources, and green technology innovation underscores the transformative potential of technology in addressing environmental challenges and fostering sustainable development. Against this backdrop, this study examines whether the digital economy promotes green technological innovation and uses a two-way fixed effect based on the data of A-share listed companies in Shanghai and Shenzhen from 2011 to 2020. The mediation effect model and threshold model are used to explore the possible mechanism played by data resources. The study shows that the development of the digital economy significantly promotes enterprises' green technology innovation. This positive effect is especially prominent in the east-central region, second-tier cities, and non-resource cities. In contrast, the digital economy inhibits firms' green technology innovation in Tier 4 and Tier 5 cities and resource-based cities. Mechanism analysis shows that the digital economy can further promote enterprise green technology innovation by developing data resources. The threshold effect indicates a double threshold variable for data resources. The digital economy has differentiated effects on enterprise green technology innovation in different digital resource intervals. It provides a new perspective for understanding green technology innovation in the context of the digital economy and data resources.

The effect of education expenditure on air pollution: Evidence from China

Education expenditure is essential in mitigating air pollution, but the relationship between education expenditure and air pollution lacks in-depth discussion. Utilizing data at the county level in China during 2007–2021, this study estimates the effect of education expenditure from local governments on air pollution. Our findings demonstrate that education expenditure significantly and negatively affects air pollution, which remains robust after addressing endogeneity. The mechanism analysis presents that education expenditure reduces air pollution through the composition, technique, and income effects. The heterogeneity analysis indicates that the impact of education expenditure exhibits marked regional heterogeneity. Specifically, the role of education expenditure is significant in strong regulation, key, eastern, and central regions. By considering interaction terms, we identify the moderating effects of human capital, economic development, infrastructure construction, and public service for education expenditure. The cost-benefit analysis emphasizes that education expenditure improves social welfare. Our findings can inspire local governments to place more emphasis on air quality and public education expenditure.

Synergistic effects of peracetic acid and free ammonia pretreatment on anaerobic fermentation of waste activated sludge to promote short-chain fatty acid production for polyhydroxyalkanoate biosynthesis: Mechanisms and optimization

Peracetic acid (PAA) combined with free ammonia (FA) pretreatment can be utilized to promote anaerobic fermentation (AF) of waste activated sludge (WAS) to produce short-chain fatty acids (SCFAs), and the resulting SCFAs are desirable carbon sources (C-sources) for polyhydroxyalkanoate (PHA) biosynthesis. This work aimed to determine the optimum conditions for PAA + FA pretreatment of sludge AF and the feasibility of using anaerobic fermentation liquor (AFL) for PHA production. To reveal the mechanisms of integrated pretreatment, the impacts of PAA + FA pretreatment on different stages of sludge AF and changes in the microbial community structure were explored. The experimental results showed that the maximum SCFA yield reached 491.35 ± 6.02 mg COD/g VSS on day 5 after pretreatment with 0.1 g PAA/g VSS +70 mg FA/L, which was significantly greater than that resulting from PAA or FA pretreatment alone. The mechanism analysis showed that PAA + FA pretreatment promoted sludge solubilization but strongly inhibited methanogenesis. According to the analysis of the microbial community, PAA + FA pretreatment changed the microbial community structure and promoted the enrichment of bacteria related to hydrolysis and acidification, and Proteiniclasticum, Macellibacteroides and Petrimonas became the dominant hydrolytic and acidifying bacteria. Finally, after alkali treatment, the AFL was utilized for batch-mode PHA production, and a maximum PHA yield of 55.05 wt% was achieved after five operation periods.

Design and Simulation of Flexible Rail Hoisting System Without Wind Rope

Under extreme terrain conditions, there is no site to arrange the control rope retraction system. In this paper, a flexible guide rail hoisting system is designed to replace the traditional transmission tower wind rope hoisting method. Taking the JC27151CG tower assembly as the object, the design of the flexible guide rail hoisting system is carried out, and the ADAMS software is used to establish the dynamic model of the flexible guide rail hoisting system. The mechanical analysis of the flexible guide rail hoisting system is carried out from the perspectives of statics and dynamics.

Does digital economy affect corporate ESG performance? New insights from China

With the explosive development and innovation of digital and information technologies, a big data era has arrived in China. We examine the influence of the digital economy on corporate ESG performance using panel data from A-share listed firms in China between 2011 and 2021. First, we find that the digital economy can significantly improve corporate ESG performance, especially in environmental and governance dimensions. Second, our mechanism analysis identifies two channels—green innovation and digital transformation—through which the digital economy affects corporate ESG performance. Third, our cross-sectional analysis shows that the effect of the digital economy on corporate ESG performance is more pronounced for listed firms located in areas with lower economic levels, facing higher financing constraints, and belonging to high-polluting industries. Finally, our results remain robust after conducting a series of tests. Our study underscores the policy implication that embracing and promoting digital economy initiatives can serve as a potent lever to enhance corporate ESG performance, particularly in environmental and governance dimensions.

Potential contributions of digital finance to alleviating the ‘low-end lock-in’ dilemma for green innovation in enterprises

As climate change risks intensify worldwide, green technological innovation by enterprises has become a crucial factor affecting the balance between economic development and ecological governance. This paper utilizes data from Chinese A-share listed companies in heavily polluting industries from 2011 to 2021 to investigate the impact and mechanism of the knowledge spillover effect of enterprise digital finance development on the phenomenon of ‘low-end lock-in’ in green innovation. The study finds that digital finance development significantly promotes green innovation in enterprises, with a more pronounced enhancement in high-end green innovation output, thereby mitigating the phenomenon of ‘low-end lock-in’ in green innovation. Mechanism analysis reveals that the development of digital finance in enterprises facilitates high-end green innovation by alleviating financing constraints and enhancing internal control levels through internal and external governance structures. Heterogeneity tests indicate that the promotion effect of digital finance development on high-end green innovation is more pronounced in samples of state-owned enterprises, large and medium-sized enterprises, and enterprises in central and eastern regions. This paper constructs an index of digital finance development for enterprises through text analysis, providing theoretical support for micro-enterprise research on digital finance development and empirical support for the impact of financial development trends on theories of enterprise green innovation.

Enhancing airless tire performance for military vehicles: natural rubber compound with carbon black Fillers N220 and N550 with dynamic mechanical analysis approach

Enhancing airless tire performance for military vehicles: natural rubber compound with carbon black Fillers N220 and N550 with dynamic mechanical analysis approach