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In the field of ultrasonic-assisted micro-forming, in addition to acoustic softening, impact effects also play a significant role, especially in terms of influencing the deformation behavior of surfaces, such as by generating more deformation on surface asperity. In this study, to understand the mechanisms involved in the effect of an impact, ultrasonic-assisted micro-forging tests were conducted on commercially pure copper, pure aluminum, and pure titanium. A method that can measure the increment in the temperature during ultrasonic vibration was developed. As a result, changes in the surface temperature of the material under the impact effect and acoustic softening were measured. It is indicated that, during ultrasonic vibration, the heat generated through acoustic softening is very limited and the main heat increase occurs after the impact effect. Once the impact effect occurs, the surface temperature increases with increasing amplitude. Nevertheless, for materials with different crystal structures, the influences of the impact effect are also different. The surfaces of copper and aluminum soften, creating more surface deformation, but the exact opposite effect is seen on a titanium surface. Observing the evolution of the microstructure on the material surface with EBSD demonstrates that the impact effect on FCC materials can reach deeper below the surface in terms of temperature diffusion compared to titanium. Meanwhile, the impact effect in the case of titanium causes the regeneration of twinning, which is reduced under the influence of the acoustic softening effect, consequently resulting in strain hardening. [ABSTRACT FROM AUTHOR]

Grinding is an ultra-precision machining technology. The grinding force and grinding heat emerge as pivotal physical parameters. Excessive grinding temperature can engender unwarranted thermal damage to the processed material. In cup grinding wheel face grinding, employing a singular abrasive grain discrete heat source method enables a more precise establishment of the face grinding temperature field. Cross tracks of abrasive exist widely in cup grinding wheel, and the influence of cross-point temperature should be considered in order to accurately establish the grinding temperature field model. Thus, a single-grain discrete point heat source superposition temperature field analytical model was established. Through trochoid feed scratch experiments, the variation law of thermal effect of cross-points under different cutting depth is verified. The experimental findings reveal conspicuous changes in cutting force and cutting heat at the entry and exit positions of the scratch intersection region. Moreover, the abrasive grain scratch sustains more severe damage compared to other regions. The energy change caused by the impact effect is the key factor leading to the temperature change at the intersection. The energy lost at the entrance of the intersection position is close to the energy of the impact effect. With the increase of the cutting depth, the ratio of the two tends to converge towards 1, ranging from 0.868 to 0.932 to 0.965. The error between the theoretical model and experimental verification is less than 5%, indicating the single-particle discrete heat source superposition temperature field model can well characterize the grinding surface temperature field caused by cross-point effect, which lays a foundation for the grinding heat theory based on trochoid model. [ABSTRACT FROM AUTHOR]

[Display omitted] • Impact of artificial intelligence development on water pollution is analysed. • Artificial intelligence technologies can help reduce levels of water pollution. • Conditions in central China need examining to formulate a targeted development plan. • Results remain valid after instrumental variables regression and robustness test. Analysing the impacts of AI development on water pollution is of great significance for improving water environment management measures and promoting global sustainable development. In this study, macro and micro panel data of China from 2008 to 2019 were used to measure the development level of AI at the industry and provincial levels in China, and a panel data regression model was constructed to analyse the effects of AI development on water pollution and regional heterogeneity. The measurement results show that the development level of AI is increasing. Among the six industries, the intelligence level of the manufacturing industry has developed the fastest, by approximately 48.74 times compared with the baseline. At the provincial level, Guangdong Province made the greatest progress in intelligence level, increasing by approximately 23.6 times. The regression results show that AI technology is helpful in reducing the level of water pollution, and this conclusion remains valid after the regression of instrumental variables and robustness testing. In terms of regional heterogeneity, AI technology can significantly reduce the degree of water pollution in eastern and western China. However, the development of AI technology in the central region has no significant impact on water pollution, and a risk of increasing the degree of water pollution exists. The reasons may be that the eastern region has high levels of economic vitality and technological innovation and a strong ability to transform AI achievements, which can significantly improve the water environment. Industrial support policies in the western region are strong, and the application of AI can quickly improve production methods and significantly reduce water pollution levels. In comparison, the levels of economic development, technological innovation, and policy support in the central region need to be strengthened, so the environmental effect of AI is not significant. [ABSTRACT FROM AUTHOR]

The utilization of baffle structures as a highly effective strategy for mitigating debris flow has attracted significant scholarly attention in recent years. Although the predominant focus of existing research has been on augmenting the energy dissipation capabilities of baffle structures, their deformation behavior under impact load has not been extensively investigated. Addressing this research gap, the current study systematically designs a series of physical model experiments, incorporating variables such as baffle height, shape, and various combinations of baffle types to comprehensively analyze the deformation characteristics of baffles subjected to debris flow impact. The experimental results reveal that the deformation of baffle group structures demonstrates a marked non-uniform spatial distribution and exhibits a latency effect. Additionally, distinct baffle configurations show considerable variations in peak strain, suggesting that combining different baffle shapes can not only optimize energy dissipation but also enhance resistance to deformation. Moreover, the relationship between baffle height and the development of deformation in relation to energy dissipation capacity is inconsistent, indicating that deformation must be a key consideration in the design of baffle structures. Consequently, this paper advocates for the formulation of a deformation-based design strategy for baffle structures, with the findings presented herein providing a foundational reference for future studies. [ABSTRACT FROM AUTHOR]

The impact of the digital economy on the healthcare sector is becoming increasingly profound. This article focuses on the relationship between the development of China’s digital economy and medical and health services supply. Based on panel data from 30 provinces in China from 2012 to 2021, the CRITIC weight method was applied to measure the supply capacity of medical and health services and the level of digital economy development, and the kernel density estimation method and Dagum Gini coefficient method was used to characterize the evolutionary trends and regional differences. Additionally, a two-way fixed-effects model is adopted to investigate the impact of digital economy development on medical and health services supply. The results show that both the supply capacity of healthcare services and the level of digital economy development have been increasing continuously in terms of evolutionary trends. From the perspective of regional differences, compared to the supply level of healthcare services, the regional differences in digital economy development are more significant. The intra-regional differences in medical and health services supply are greater than the inter-regional differences, while the development of the digital economy exhibits the opposite trend. The findings of this paper provide supports for China to enhance the development level of digital economy and improve supply of medical and health service.

This study establishes an evaluation index system for residents' happiness and empirically examines the impact of traffic exhaust pollution (TEP) on residents' happiness using data from the China General Social Survey (CGSS), Statistical Yearbook, and European Center for Medium-Range Weather Forecasts (ECMWF). The findings demonstrate that TEP significantly influences residents' happiness: a 1 unit increase in TEP leads to a 0.105 unit increase in life satisfaction, a 0.233 unit decrease in emotional experience, a 0.109 unit decrease in social adaptation, and a 0.088 unit decrease in overall happiness. Mediation analysis reveals two pathways of influence: economic prosperity resulting from TEP enhances residents' happiness, while travel intention diminishes it. Heterogeneity analysis indicates variations across time windows, population groups, and regions. The impact of TEP on life satisfaction becomes evident after six months, with the effect on emotional experience remaining statistically significant for up to nine months. Social adaptation and overall happiness continue to be significantly affected for 15 months, while the impact on self-actualization persists even longer. Vulnerable groups including middle-aged individuals, seniors, women, rural residents, and those residing in economically developed areas are more prone to experiencing negative emotions and dissatisfaction with life due to TEP exposure. Furthermore regression analyses reveal that household income levels, public budge, travel intention play mediating roles between TEP exposure and happiness outcomes. These findings significantly contribute to the comprehension of the influence of TEP on residents' happiness, with the objective of fostering the high-quality advancement of environmental happiness initiatives and enhancing residents' overall welfare. [ABSTRACT FROM AUTHOR]

Urban-rural development is an important driving force for regional economic growth. The existing researches have studied this issue from various perspectives, but they ignore the impact of big data on the economy. In the post pandemic era, big data, as an emerging production factor, has a significant indicative effect in promoting urban-rural economic recovery and fostering new business forms. Therefore, fully considering the factor of big data can help reveal its impact mechanism on urban-rural economic growth in the post-epidemic period. Based on the data of 30 provinces and cities in China, this paper introduced big data on the basis of traditional models and constructed a multi-dimensional factor indicator system. At the same time, the panel regression model was established by using unit root test, Hausman test and precision test. Through benchmark regression and heterogeneity analysis, the impact of urban-rural development factors on economic growth was discussed. The results showed that the panel model passed all tests, and its regression error was stable below 5 %. Transportation, technology, and the three major industries can all promote positive economic growth, with a significance of 1 %. The three industries' contribution to economic growth ranks the third, second and first industries in order. In addition, the good ecological environment contributes to the benign economic growth during the study period. A 1 % increase in forest cover would drive economic growth by 0.215 %. But the impact of public's attention on the overall economy was an indirect effect manifested through its physical industries.The regional heterogeneity indicated that each element had different effects on economic development in eastern, central and western regions. Based on its results, this paper proposed suggestions for each region. In addition, this study found that the Internet attention reflected by big data did not directly drive economic growth, but affected economic growth through indirect channels such as information flow and resource allocation of real industries. This study provided data support for the existing theoretical review, and provided policy reference for the rational planning and industrial layout of China's regional economy.

Abstract Background As the exploitation of marine resources intensifies, the impact of submarine landslides on underwater structures has become a significant issue. Existing research primarily focuses on the impact on pipelines, often neglecting the actual deformation and mechanical response of underwater structures under impact loads in numerical simulations, thus complicating the evaluation of the reliability of these engineering structures in extreme conditions. Moreover, the dynamic response of bucket foundations, a common form of underwater base, under the effect of submarine landslide impacts remains unclear. Methods To address this knowledge gap, we have developed a fluid-structure coupling system that employs the coupled Smoothed Particle Hydrodynamics (SPH)-Finite Element Method (FEM) to investigate a single impact process and analyze the displacement response of bucket foundations within a water-offshore landslide-bucket foundationsubgrade context. The accuracy of this developed method has been systematically verified through comparisons with previous experimental and numerical results. Results During a submarine landslide impact event, the impact force demonstrates a distinct decrease followed by stabilization, and the displacement response of the bucket foundation exhibits a rebound effect after reaching its maximum value. Furthermore, we conducted an extensive analysis of different impact angles for underwater data centers equipped with multi-bucket foundations. Our study revealed that group-bucket foundations experience a combined translation-turnover failure when subjected to submarine landslide impacts, and the most unfavorable scenario for such impact is identified. The research introduces a novel numerical simulation approach for investigating the impact of submarine landslides on complex underwater structures.

Background: As the exploitation of marine resources intensifies, the impact of submarine landslides on underwater structures has become a significant issue. Existing research primarily focuses on the impact on pipelines, often neglecting the actual deformation and mechanical response of underwater structures under impact loads in numerical simulations, thus complicating the evaluation of the reliability of these engineering structures in extreme conditions. Moreover, the dynamic response of bucket foundations, a common form of underwater base, under the effect of submarine landslide impacts remains unclear. Methods: To address this knowledge gap, we have developed a fluid-structure coupling system that employs the coupled Smoothed Particle Hydrodynamics (SPH)-Finite Element Method (FEM) to investigate a single impact process and analyze the displacement response of bucket foundations within a water-offshore landslide-bucket foundationsubgrade context. The accuracy of this developed method has been systematically verified through comparisons with previous experimental and numerical results. Results: During a submarine landslide impact event, the impact force demonstrates a distinct decrease followed by stabilization, and the displacement response of the bucket foundation exhibits a rebound effect after reaching its maximum value. Furthermore, we conducted an extensive analysis of different impact angles for underwater data centers equipped with multi-bucket foundations. Our study revealed that group-bucket foundations experience a combined translation-turnover failure when subjected to submarine landslide impacts, and the most unfavorable scenario for such impact is identified. The research introduces a novel numerical simulation approach for investigating the impact of submarine landslides on complex underwater structures. [ABSTRACT FROM AUTHOR]

The impact effect can cause structural damage to a transmission tower's foundation and affect its overall stability. In order to study the influence of the impact effect on the stability of transmission tower foundations, a three-dimensional finite element numerical simulation method was used to investigate the variations in the extent of damage, displacement, and inclination degree of a transmission tower foundation under different impact velocities, impact durations, impactor shapes, and impact locations. The results show that as the impact velocity increases, the damage value of the transmission tower foundation continuously increases, and the damaged area expands. The lateral displacement value increases continuously with the duration of the impact effect, and the variation in lateral displacement follows a linear function distribution. The inclination degree of the transmission tower foundation increases continuously with increased impact duration and can lead to overturning failure. A smaller impact contact area results in a larger compressive damage value for the transmission tower foundation, and different impact contact areas lead to different modes of failure for the transmission tower foundation. The damage value and damaged area of the transmission tower foundation vary with the location of the impact. By comparing the deformation of the transmission tower foundation before and after reinforcement, it is evident that the reinforcement design can significantly improve the deformation resistance and anti-overturning capacity of the transmission tower foundation. [ABSTRACT FROM AUTHOR]

In the field of ultrasonic-assisted micro-forming, in addition to acoustic softening, impact effects also play a significant role, especially in terms of influencing the deformation behavior of surfaces, such as by generating more deformation on surface asperity. In this study, to understand the mechanisms involved in the effect of an impact, ultrasonic-assisted micro-forging tests were conducted on commercially pure copper, pure aluminum, and pure titanium. A method that can measure the increment in the temperature during ultrasonic vibration was developed. As a result, changes in the surface temperature of the material under the impact effect and acoustic softening were measured. It is indicated that, during ultrasonic vibration, the heat generated through acoustic softening is very limited and the main heat increase occurs after the impact effect. Once the impact effect occurs, the surface temperature increases with increasing amplitude. Nevertheless, for materials with different crystal structures, the influences of the impact effect are also different. The surfaces of copper and aluminum soften, creating more surface deformation, but the exact opposite effect is seen on a titanium surface. Observing the evolution of the microstructure on the material surface with EBSD demonstrates that the impact effect on FCC materials can reach deeper below the surface in terms of temperature diffusion compared to titanium. Meanwhile, the impact effect in the case of titanium causes the regeneration of twinning, which is reduced under the influence of the acoustic softening effect, consequently resulting in strain hardening.

The utilization of baffle structures as a highly effective strategy for mitigating debris flow has attracted significant scholarly attention in recent years. Although the predominant focus of existing research has been on augmenting the energy dissipation capabilities of baffle structures, their deformation behavior under impact load has not been extensively investigated. Addressing this research gap, the current study systematically designs a series of physical model experiments, incorporating variables such as baffle height, shape, and various combinations of baffle types to comprehensively analyze the deformation characteristics of baffles subjected to debris flow impact. The experimental results reveal that the deformation of baffle group structures demonstrates a marked non-uniform spatial distribution and exhibits a latency effect. Additionally, distinct baffle configurations show considerable variations in peak strain, suggesting that combining different baffle shapes can not only optimize energy dissipation but also enhance resistance to deformation. Moreover, the relationship between baffle height and the development of deformation in relation to energy dissipation capacity is inconsistent, indicating that deformation must be a key consideration in the design of baffle structures. Consequently, this paper advocates for the formulation of a deformation-based design strategy for baffle structures, with the findings presented herein providing a foundational reference for future studies.

The self‐centering (SC) pier system exhibits different mechanical behaviors under an earthquake compared with that in quasi‐static experiments, especially the impact effect on the rocking interface. Published theoretical analysis and experiments had indicated that the impact events significantly affected the rocking motion, including extra energy dissipation, greater contact stress, and even more serious damage. To describe the impact mechanism more clearly and obtain the impact responses more directly, this study investigates a dynamic theoretical model considering the impact effect and its influences on the seismic responses and rocking interface. First, a dynamic theoretical model based on the Hertz contact‐pounding model specific to the SC pier system is proposed, and the impact mechanism is described in detail. Subsequently, dynamic motion equations considering the impact effect are derived. The key parameters of the contact‐pounding element (stiffness KHertz and damping CHertz) that significantly affect the impact process are presented. The accuracy of the proposed theoretical model is verified by test data and a finite element model (FEM). Finally, the influences of the key parameters (KHertz and CHertz) on the impact force are analyzed, and the impact effect on the rocking interface is investigated. The results indicate that the impact effect significantly increases the vertical acceleration and contact stress, particularly under near‐fault earthquakes. This may cause unexpected damage on the rocking interface and should be an important consideration in the optimize design of SC pier system. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Exploring the influence of haze pollution on the inbound tourism flow is an important topic to stabilize the inbound tourism market and control the inbound tourism flow space. This paper describes the spatial evolution characteristics of haze pollution and inbound tourism flow in the Yangtze River Delta Urban Agglomeration from 2002 to 2018 by bivariate spatial autocorrelation model and standard deviation ellipse, and analyzes the effect of haze pollution on inbound tourism flow by spatial econometric model. The results show that: ➀ The spatial distribution of haze pollution and inbound tourism flow in the Yangtze River Delta Urban Agglomeration shows obvious heterogeneity and imbalance, and the spatial evolution of the two has significant "southeast-northwest" reverse coupling characteristics. ➁ From the perspective of global space, haze pollution and inbound tourism flow in the Yangtze River Delta Urban Agglomeration show negative correlation in the study period, with negative spatial dependence and aggregation effect. From the perspective of local space, there are three types of spatial clusters, namely high-low, low-high and high-high. The high-low clusters are mainly distributed in southwest Anhui and northeast Jiangsu, while Zhoushan is characterized by stable low-high cluster. The high-high cluster cities are mainly Suzhou, Jiaxing and Nantong. ➂ Haze pollution has a significant negative impact on inbound tourism flow in the local region, and has a negative spatial spillover effect on neighboring cities through spatial correlation; industrial structure, opening degree and transportation convenience also have spatial spillover effect on inbound tourism flow in adjacent areas. Finally, the paper puts forward some suggestions such as strengthening the linkage effect of regional haze prevention and control, coordinating various tourism elements to stabilize the inbound tourism market and improve the tourism competitiveness. [ABSTRACT FROM AUTHOR]

The impact effect is a crucial issue in civil engineering and has received considerable attention for decades. For the first time, this study develops hybrid machine learning models that integrate the novel Extreme Gradient Boosting (XGB) model with Particle Swam Optimization (PSO), Grey Wolf Optimizer (GWO), Moth Flame Optimizer (MFO), Jaya (JA), and Multi-Verse Optimizer (MVO) algorithms for predicting the permanent transverse displacement of circular hollow section (CHS) steel members under impact loads. The hybrid machine learning models are developed using data collected from 357 impact tests of CHS steel members. The efficacy of hybrid machine learning models is evaluated using three performance metrics. The results show that the GWO-XGB model achieves high accuracy and outperforms the other models. The values of R2, RMSE, and MAE obtained from the GWO-XGB model for the test set are 0.981, 2.835 mm, and 1.906 mm, respectively. The SHAP-based model explanation shows that the initial impact velocity of the indenter, the impact mass, and the ratio of impact position to the member length are the most sensitive parameters, followed by the yield strength of the steel member and the member length; meanwhile, member diameter and member thickness are the parameters least sensitive to the permanent transverse displacement of CHS steel members. Finally, this study develops a web application tool to help rapidly estimate the permanent transverse displacement of CHS steel members under impact loads. [ABSTRACT FROM AUTHOR]

Optimizing the allocation of university resources to improve the efficiency of inputs and outputs is an important issue for the high-quality development of universities. In recent years, China has become an important growth pole for the development of global higher education. In particular, Chinese agricultural universities, with their distinctive disciplinary characteristics and outstanding professional advantages, have made important contributions to the sustainable development of agricultural education around the world. In contrast, academic research on the efficiency of resource allocation in Chinese agricultural universities is very limited. To fill this gap, this study was guided by econometrics and took high-level agricultural universities in China as the research object to measure the effects of financial investment, disciplinary differences, and development level on the level of resource allocation efficiency of universities. With the help of a data envelopment model (DEA) and a Malmquist index decomposition model, we found that the overall level of resource allocation efficiency in the sample universities was high, but there were great disparities in resource input–output effectiveness between universities. In many universities, marginal inputs exceeded marginal outputs, resulting in input redundancy and resource wastage. In addition, this study shows that for high-level agricultural universities, the regression of capital input technology is preventing a sustained increase in productivity, which places the total factor productivity of resource allocation in a diminishing state. [ABSTRACT FROM AUTHOR]

In order to study the vehicle impact effect on the fatigue assessment for steel bridge decks, the segmental finite element model is built of a continuous steel box girder bridge, and 7-day Weigh-in-Motion(WIM) data of Lianyungang-to-Horgos Expressway is selected to carry out fatigue assessment of typical details. The influence law of impact factors on the fatigue assessment result is analyzed, and the applicability of impact factors in different current specifications is studied. Research results show that the vehicle impact effect has a significant influence on the fatigue assessment results of steel bridge decks. Obvious differences exist in impact effects of different details, the impact effect of rib-to-deck detail is the largest, and the rib-to-rib detail is the smallest. The bridge deck pavement condition has great influence on the impact effect of steel bridge deck, fatigue assessment result of “worse” pavement condition is 3. 30-3. 91 times of “excellent” pavement condition. The vehicle impact effect should be fully considered when the fatigue assessment is performed, and reasonable impact factors should be adopted according to pavement conditions and detail types. [ABSTRACT FROM AUTHOR]

Taking Haixin Bridge as an example, the structural response of a new type arch bridge composed of an inclined arch and a curved beam under cable breaking is analyzed numerically. The cable breaking at different positions, different numbers of broken cables and different ways of breaking are modeled and calculated, and the remaining cables' internal force and main girder's deflection are selected as research indexes to evaluate the degree of impact effect of broken cables on the bridge. The numerical results show that (1) duration time of cable breaking is an important factor affecting the impact effect of the bridge, when the cable breaking time is less than 1% of the first order natural vibration period of the structure, the dynamic response caused by cable breaking no longer variates with time; (2) for the cables adjacent to the breaking cable at equal distances, the cable with a shorter length will carry more released force of breaking cable than the longer, and the impact effect is more significant; (3) the dynamic response of displacement and cable force caused by cables at different locations are different, a cable located in the L/4 arch rib area suddenly breaking shows the largest dynamic response; (4) it is feasible to take the dynamic amplification factor (DAF) of cable force and the main girder's deflection as 2, but it is unsafe to take the DAF of the arch rib's deflection as 2; (5) the dynamic response of multiple cables breaking at the same time cannot be simplified as a linear superposition of single cable breaks one by one, and the amplification effect becomes more significant with the increase of the number of broken cables. These conclusions can provide guidance for structural safety assessment of similar arch bridges after cable breakage. [ABSTRACT FROM AUTHOR]

The impact effect can cause structural damage to a transmission tower’s foundation and affect its overall stability. In order to study the influence of the impact effect on the stability of transmission tower foundations, a three-dimensional finite element numerical simulation method was used to investigate the variations in the extent of damage, displacement, and inclination degree of a transmission tower foundation under different impact velocities, impact durations, impactor shapes, and impact locations. The results show that as the impact velocity increases, the damage value of the transmission tower foundation continuously increases, and the damaged area expands. The lateral displacement value increases continuously with the duration of the impact effect, and the variation in lateral displacement follows a linear function distribution. The inclination degree of the transmission tower foundation increases continuously with increased impact duration and can lead to overturning failure. A smaller impact contact area results in a larger compressive damage value for the transmission tower foundation, and different impact contact areas lead to different modes of failure for the transmission tower foundation. The damage value and damaged area of the transmission tower foundation vary with the location of the impact. By comparing the deformation of the transmission tower foundation before and after reinforcement, it is evident that the reinforcement design can significantly improve the deformation resistance and anti-overturning capacity of the transmission tower foundation.

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, we present a novel reduced Galinstan-based microfluidic energy harvester, which can converse kinetic energy to electricity from an arbitrary vibration source. Firstly, the wetting behaviors of reduced Galinstan are performed, which shows a robust impact effect on polymer substrates. Moreover, the electric circuit model of the reduced Galinstan-based energy harvester is made and discussed by the use of the EDLCs (electrical double layer capacitors). After modeling, the microfluidic energy harvester with coplanar microfluidic channels is designed and fabricated. Finally, the performance of the microfluidic energy harvester is investigated, which can harvest multi-direction vibration energy. The experiment results demonstrate that the novel reduced Galinstan-based microfluidic energy harvester is suitably and uniquely applied in a complex vibration environment. [ABSTRACT FROM AUTHOR]

The impact of the digital economy on the healthcare sector is becoming increasingly profound. This article focuses on the relationship between the development of China's digital economy and medical and health services supply. Based on panel data from 30 provinces in China from 2012 to 2021, the CRITIC weight method was applied to measure the supply capacity of medical and health services and the level of digital economy development, and the kernel density estimation method and Dagum Gini coefficient method was used to characterize the evolutionary trends and regional differences. Additionally, a two-way fixed-effects model is adopted to investigate the impact of digital economy development on medical and health services supply. The results show that both the supply capacity of healthcare services and the level of digital economy development have been increasing continuously in terms of evolutionary trends. From the perspective of regional differences, compared to the supply level of healthcare services, the regional differences in digital economy development are more significant. The intra-regional differences in medical and health services supply are greater than the inter-regional differences, while the development of the digital economy exhibits the opposite trend. The findings of this paper provide supports for China to enhance the development level of digital economy and improve supply of medical and health service., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Guan, Xu and Huang.)

To study the mechanism of strain rate on the grinding damage of zirconia ceramics (ZrO 2), a ZrO 2 surface grinding experiment was conducted to analyse the effect of strain rate on the grinding force, surface morphology and subsurface cracks. As the strain rate increased, the grinding force decreased significantly; the grinding scratches gradually became continuous and clear, and the grinding surface gradually became smooth. Increasing the strain rate can greatly reduce the length of subsurface cracks; however, the length of subsurface cracks drops slowly and tends to stabilise when the strain rate reaches a certain value. The direction of subsurface cracks is related to the internal defects of the material, and there is a trend of approaching the surrounding cracks and defects. When the internal defects were stimulated by the impact stress wave, the cracks started to grow and expand from the tip, and the expanding direction remained at approximately 125° in the direction of the defect length. The results show that an increase in the grinding strain rate can effectively improve the grinding quality of zirconia ceramics, which has guiding significance for practical production. [ABSTRACT FROM AUTHOR]

A modified VG model considering both pore ratio and temperature effect is constructed. Based on the wet-thermal elasticity theory and mixture theory, coupled thermo-hydro-mechanical (THM) equations for moisture migration, heat transfer, and deformation in unsaturated soil are derived. The numerical implementation of the coupled theory was implemented by secondary development in the finite element platform. The validity of the established theoretical equation was verified by comparing it with the experimental data. Then the THM coupling response characteristics and internal mechanism of axisymmetric soil samples were numerically analyzed. Study shows that the water in unsaturated soil migrates from high-temperature zone to low-temperature zone under temperature load, and the permeability will change during the process of moisture absorption and dehydration. Particular attention should pay to the reasonable determination of the parameters in the modified VG model for the warming and cooling process of different measurement points during the numerical calculation. The higher the heat source temperature, the greater the saturation at the specific measurement point of the soil sample at thermal stability. The lower the heat source temperature, the shorter the time required for the saturation to stabilize at the specific measuring point. The volumetric strain of unsaturated soil results from a combination of wet expansion and thermal expansion, which is dominated by wet expansion near the heat source and mainly by thermal expansion far from the heat source. The change of the total displacement with time is dominated by the z-direction displacement, and its change trend along the radial direction is similar to that in the r-direction. The peak of the total displacement curve keeps moving backward with time.

The impact effect is a crucial issue in civil engineering and has received considerable attention for decades. For the first time, this study develops hybrid machine learning models that integrate the novel Extreme Gradient Boosting (XGB) model with Particle Swam Optimization (PSO), Grey Wolf Optimizer (GWO), Moth Flame Optimizer (MFO), Jaya (JA), and Multi-Verse Optimizer (MVO) algorithms for predicting the permanent transverse displacement of circular hollow section (CHS) steel members under impact loads. The hybrid machine learning models are developed using data collected from 357 impact tests of CHS steel members. The efficacy of hybrid machine learning models is evaluated using three performance metrics. The results show that the GWO-XGB model achieves high accuracy and outperforms the other models. The values of R2, RMSE, and MAE obtained from the GWO-XGB model for the test set are 0.981, 2.835 mm, and 1.906 mm, respectively. The SHAP-based model explanation shows that the initial impact velocity of the indenter, the impact mass, and the ratio of impact position to the member length are the most sensitive parameters, followed by the yield strength of the steel member and the member length; meanwhile, member diameter and member thickness are the parameters least sensitive to the permanent transverse displacement of CHS steel members. Finally, this study develops a web application tool to help rapidly estimate the permanent transverse displacement of CHS steel members under impact loads.

Taking Haixin Bridge as an example, the structural response of a new type arch bridge composed of an inclined arch and a curved beam under cable breaking is analyzed numerically. The cable breaking at different positions, different numbers of broken cables and different ways of breaking are modeled and calculated, and the remaining cables’ internal force and main girder’s deflection are selected as research indexes to evaluate the degree of impact effect of broken cables on the bridge. The numerical results show that (1) duration time of cable breaking is an important factor affecting the impact effect of the bridge, when the cable breaking time is less than 1% of the first order natural vibration period of the structure, the dynamic response caused by cable breaking no longer variates with time; (2) for the cables adjacent to the breaking cable at equal distances, the cable with a shorter length will carry more released force of breaking cable than the longer, and the impact effect is more significant; (3) the dynamic response of displacement and cable force caused by cables at different locations are different, a cable located in the L/4 arch rib area suddenly breaking shows the largest dynamic response; (4) it is feasible to take the dynamic amplification factor (DAF) of cable force and the main girder’s deflection as 2, but it is unsafe to take the DAF of the arch rib’s deflection as 2; (5) the dynamic response of multiple cables breaking at the same time cannot be simplified as a linear superposition of single cable breaks one by one, and the amplification effect becomes more significant with the increase of the number of broken cables. These conclusions can provide guidance for structural safety assessment of similar arch bridges after cable breakage.

Experimental and numerical behaviour of steel test specimens with various types of joints is investigated in this study. A drop weight test setup with necessary test equipment is used for this purpose. The mass and drop height of the hammer is taken to be constant so that the same impact energy can be applied on test specimens. The acceleration, displacement, impact load, drop numbers and drop durations, are obtained through experimental study. In addition, development of damage to test specimens is observed during tests. Numerical analyses of behaviour of test specimens under impact load are also conducted to verify test results using the Abaqus software, and a comparison of results is made.

Steel sections with four different joint types, subjected to sudden impact, are investigated in this study. A drop weight test setup was developed for this purpose. Impact tests were performed for two different energy levels. Acceleration-time, displacement-time, impact load-time, and impact load-displacement graphs were developed and presented. It was established that the behaviour of test specimens is affected by joint types and impact energy applied. Failure damage situation occurs earlier when rigidity of specimens decreases and when higher level of impact energy is applied.

Urban-rural development is an important driving force for regional economic growth. The existing researches have studied this issue from various perspectives, but they ignore the impact of big data on the economy. In the post pandemic era, big data, as an emerging production factor, has a significant indicative effect in promoting urban-rural economic recovery and fostering new business forms. Therefore, fully considering the factor of big data can help reveal its impact mechanism on urban-rural economic growth in the post-epidemic period. Based on the data of 30 provinces and cities in China, this paper introduced big data on the basis of traditional models and constructed a multi-dimensional factor indicator system. At the same time, the panel regression model was established by using unit root test, Hausman test and precision test. Through benchmark regression and heterogeneity analysis, the impact of urban-rural development factors on economic growth was discussed. The results showed that the panel model passed all tests, and its regression error was stable below 5 %. Transportation, technology, and the three major industries can all promote positive economic growth, with a significance of 1 %. The three industries' contribution to economic growth ranks the third, second and first industries in order. In addition, the good ecological environment contributes to the benign economic growth during the study period. A 1 % increase in forest cover would drive economic growth by 0.215 %. But the impact of public's attention on the overall economy was an indirect effect manifested through its physical industries.The regional heterogeneity indicated that each element had different effects on economic development in eastern, central and western regions. Based on its results, this paper proposed suggestions for each region. In addition, this study found that the Internet attention reflected by big data did not directly drive economic growth, but affected economic growth through indirect channels such as information flow and resource allocation of real industries. This study provided data support for the existing theoretical review, and provided policy reference for the rational planning and industrial layout of China's regional economy., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Large blocks of drift ice have posed a strong impact on the open channels in the long-distance water delivery projects in the alpine regions. The drift ice is easy to form with the different speeds and compression strength in the high latitudes of northwestern China, especially the north of 35°N latitude. Particularly, the ice period lasts for 4 to 5 months in the cold and dry winter, covering from the freezing in November to the open in the following spring. The long-term collision of drift ice can cause some serious damage to the concrete lining of an open channel, such as cracking or peeling of the surface. The lining structure can result in different degrees of damage and deformation, even a threat to the long-term stability of water supply, including the safe operation of the open channel, irrigation of farmland, and water use for humans and animals. Therefore, this study aims to clarify the impact of the drift ice on the open delivery channels in the long-distance water delivery projects in the alpine regions. A collision model of the drift ice and open channels was also established as a water-air coupling medium using the ANSYS/LS-DYNA platform. Specifically, the collision motion equation of drift ice in the open channel was obtained, according to the display of time integration. The contact-collision process was assumed as a symmetric penalty function. The fluid-structure coupling calculation was then implemented considering the coupling effect between water-air-flow ice-open channels. After that, LS-DYNA SOLVER software was used to simulate the collision and extrusion of drift ice and open channel under different working conditions. As such, the degree of the collision was classified to evaluate the damage caused by the drift ice to the lining of the open channel. An indoor model test was carried out to verify the model. A damage law of drift ice was thus found in the water-air coupling medium when colliding with the open channel. The results showed that there was an approximate Pseudo-Voigt function peak curve relationship for the maximum equivalent stress and the maximum displacement in the X direction of the impact of the ice velocity on the open channel lining. Besides, there was an approximately linear relationship for the maximum equivalent stress and the maximum displacement in the X direction of the impact of drift ice compression strength on the lining of open channels. Furthermore, a combination interval posed a significant impact on the open channel lining, where the compressive strength of the flowing ice was 1.825-3.199 MPa, and the speed of the flowing ice was 3.5-4.5 m/s. This equivalent stress value of impact was 4.3-16.8 MPa, and the maximum displacement value in the X direction was 2.59×10-5-5.52×10-5 m. More importantly, a two-factor combination was posed the greatest impact on the open channel lining impact, where the flow ice compression strength of 3.059 MPa, and the flow ice velocity of 4.0 m/s. This equivalent stress value of impact was 16.8 MPa, and the maximum displacement value in the X direction was 5.52×10-5 m. By contrast, the combination interval presented a fewer outstanding impact on the open channel lining, where the drift ice velocity of 0.5-1.0 m/s, and the compressive strength was 1.825-2.375 MPa. This equivalent stress of impact was 0.7-2.8 MPa, and the maximum displacement in the X direction was 0.24×10-5-0.52×10-5 m. Therefore, there was a significant correlation between the temperature and the compressive strength of drift ice, while the flow velocity and the speed of drift ice. Correspondingly, the influence of the ice load needed to be considered in the design stage of the open channel lining structure. The findings can also provide sound theoretical and technical support to the safe operation of long-distance water transportation projects for the alpine regions in winter. [ABSTRACT FROM AUTHOR]

It can be challenging to analyze Reinforced Concrete (RC) sandwich plates with hollow structures under impact loads in terms of crushing, punching, cracking, and crack trajectories via static and dynamic equations. In the literature, the finite element solutions were provided after determining the behaviors of the materials based on the test results. Therefore, it is required to test the behaviors of RC plates. To this end, the behaviors of sandwich plates under impact loads were experimentally analyzed in this study. The sandwich plates were manufactured by cutting Polyester Foams (PF) into hexagonal prisms, square prisms, I-type, and S-type and installing them inside the RC plates. The manufactured sandwich plates were 27% lighter than full plates. A weight of 320 kg declined freely from 2.5 m, and the load was implemented at the center of the plate at a velocity of 7.5 m/s. Similar implementations were also conducted for filled plates and the maximum displacements were measured in both types of plate tests. The measurements obtained from each test were compared to determine the sandwich plate with the core geometry which provided the highest absorption and the lowest displacement. In the analyses, the S-type core geometry exhibited greater absorption than other core geometries. [ABSTRACT FROM AUTHOR]

Blade off that occurs during operation will generate a sudden imbalance excitation and make the rotor become inertially asymmetric, which leads to large instantaneous impact load and induces more complex rotor dynamic phenomena. In order to study the transient dynamic characteristics for complex rotors suffering from blade off, a mathematical model for solving the response of the gas generator rotor in the aero-turboshaft engine is established based on the FE method and DOF condensation, in which the complex structural characteristics, transient impact load, and inertia asymmetry of the rotor are considered. The complex impeller structure is modeled by piecewise linear fitting with cylindrical beam elements and tapered beam elements. Without loss of generality, the modeling method suitable for complex rotors is verified through a general complex test rotor with modal experiments. Based on this, the responses are solved for carrying out parametric studies and an understanding of the transient dynamic characteristics of the rotor under the extreme working conditions of blade off. The results show that the blade off has a great impact effect on the time-domain waveform, frequency components, and rotor orbits. At the instantaneous stage after blade off, the complex motion is composed of synchronous motion and some lower-order natural modes excited by blade off. Although the transient responses with blade off at different rotational speeds have similar time-varying characteristics, the impact factor is sensitive to the rotating speed. Most important is that the parameter of the blade off location will not only have a significant effect on the impact factor, but also on the frequency spectrum. These dynamic characteristics as well as impact effect provide certain guidance for the fault recognition and dynamic analysis to these complex rotors suffering blade off. [ABSTRACT FROM AUTHOR]

Based on the provincial data of tourism and cultural industries from 2009 to 2019, this paper studies the impact of the integration of culture and tourism on the economic benefits of regional tourism in China. The results show that: (1) The integration level of the two industries is generally low in all provinces and regions, and the regional differences are obvious. The integration degree of the central and eastern regions is generally higher than that of the western regions. (2) The integration degree of culture and tourism has a significant positive impact on the economic benefits of regional tourism. The influence on the central and eastern regions is greater than that on the western regions. (3) The level of informatization has a positive moderating effect on the economic benefits of regional tourism caused by the integration of culture and tourism. (4) Government intervention has a negative moderating effect on the economic benefits of tourism. In addition, the level of regional economic development, accessibility and tourism resource endowment are also significant factors affecting the economic benefits of regional tourism. The results show that promoting the deep integration of culture and tourism, promoting the informatization of tourism and moderate government intervention in the industry are conducive to improving the economic benefits of regional tourism. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel reduced Galinstan-based microfluidic energy harvester, which can converse kinetic energy to electricity from an arbitrary vibration source. Firstly, the wetting behaviors of reduced Galinstan are performed, which shows a robust impact effect on polymer substrates. Moreover, the electric circuit model of the reduced Galinstan-based energy harvester is made and discussed by the use of the EDLCs (electrical double layer capacitors). After modeling, the microfluidic energy harvester with coplanar microfluidic channels is designed and fabricated. Finally, the performance of the microfluidic energy harvester is investigated, which can harvest multi-direction vibration energy. The experiment results demonstrate that the novel reduced Galinstan-based microfluidic energy harvester is suitably and uniquely applied in a complex vibration environment.

The effects of nanosecond pulse laser-generated processing Ti-6Al-4V alloy with different conditions were investigated by numerical simulations and experiments. A dynamic model of Ti-6Al-4V during laser shock processing (LSP) was established based on LS-DYNA. The attenuation characteristics and variation rules of stress waves were described. Further, the formation behaviors of residual stress fields with different power densities were discussed, and the interaction between residual stresses and plastic strains was revealed under different pulse widths. Results showed that the simulation values were consistent with the experimental results. In particular, the maximum radial velocity of node reached 8.6 m/s when the node had the strongest sparse wave, and the stress wave attenuated faster in the process of stress wave propagating from the depth of 0.1 to 0.3 mm. The maximum residual compressive stress was not at the geometric center of laser spot, but at a distance about 0.57 mm from the center of laser spot under different power densities. [ABSTRACT FROM AUTHOR]

Cylindrical liquid storage tanks are contemplated as vital structures in industrial complex whose nonlinear dynamic behavior is of crucial importance. Some of these structures around the world have demonstrated poor seismic behavior over the last few decades; consonantly a major improvement is required to reach their level of applicability. There are several methods and techniques for rehabilitation and reducing damages in these structures which among them the devices for passive control, particularly base isolators, are perceptible. Friction Pendulum System (FPS) is the most popular base isolation system which its period does not depend on the structural weight. In this research work, the efficiency of FPS is examined on decreasing the seismic responses of base isolated steel storage tanks as well as the impact effect of slider to the side restrainer. To this end, the whole mass of liquid storage tank is contemplated as three lumped masses known as convective mass, impulsive mass which is connected to tanks with corresponding spring, and rigid mass which is connected rigidly. By means of state space method the time history analysis is done applying 60 earthquake records to acquire dynamic responses under the various hazard levels i.e. SLE, DBE and MCE ground motions. The results show that the normalized base shear force in squat tank decreased 59%, 62% and 33% respectively under SLE, DBE and MCE ground motions. The reduction of normalized base shear force in slender tank is 53%, 49% and 35% under the aforementioned hazard levels. Examining the effect of side restrainer’s stiffness on the maximum responses exhibit that the impact effect must be considered particularly when the system is excited by MCE’s ground motions.

The COVID-19 pandemic has affected economic activities in the various sectors due to different levels of lockdown like border closure, stay at home, and social distancing. In this regard, energy use patterns are bound to change. The objective of this paper was to analyze the changes of energy supply and energy consumption in Taiwan through the official database due to the COVID-19 pandemic in the first quarter (Q1) of 2020. In addition, some governmental measures were addressed in response to COVID-19 impacts on renewable energy development, especially in off-shore wind power and solar photovoltaic (PV). It was revealed that the results of the change analysis in energy supply and energy consumption were in line with those in the literature. The Taiwan’s energy supply and energy consumption showed a decrease by 4.7% and 4.3% on a year-on-year basis (YoY), respectively. More consistently, the petroleum consumption per capita indicated a decreasing trend at this period, but the electricity consumption per capita showed an upward increase over the Q1 of past decade (2010–2020). However, the electricity consumption slightly increased by 2.2% mainly due to the increase of the electrical and electronic machinery industry in the industrial sector for the strong demand in overseas markets. In addition, the electricity consumption in the residential sector also increased by 5.1% in response to the lockdown measures like stay-at-home learning and working. Apart from the epidemic prevention measures for assisting the off-shore power project constructions, some financial and economic relief measures have been taken to mitigate the COVID-19 impacts on the renewable energy (RE) development, especially in solar PV system. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Liquid storage tanks are important industrial structures that must continue their performance under severe earthquakes. The induced damages caused in the past earthquakes shows their poorly behavior of these structures. One of the most effective methods to retrofit and reduce the induced forces is to use base isolation. Friction Pendulum System called FPS has better performance compared to other base isolation systems, due to its period does not depend on the weight of the structures above it. The aim of this paper is to investigate the effect of FPS under three different hazard level earthquakes (SLE, DBE and MCE). It is also, the impact effect due to contacting the slider with the side restrainers is investigated. For the required analysis, two different liquid storage tanks are considered and their responses are compared in Fixed, Isolated without considering impact and isolated with considering impact conditions. The obtained results show, increasing the hazard level of ground motions leads to decreasing the performance of FPS. It is also observed, compared to SLE and DBE earthquake ground motions the MCE has the maximum probability of impact. The results also show that, the impulsive mass displacement, overturning moment and base shear increases when the impact occurs, while the impact has no special effect on convective displacement.

Abstract The process of the gas jet from aircraft engines impacting a jet blast deflector is not only a complex fluid–solid coupling problem that is not easy to compute, but also a safety issue that seriously interferes with flight deck environment. The computational fluid dynamics (CFD) method is used to simulate numerically the impact effect of gas jet from aircraft engines on a jet blast deflector by using the Reynolds-averaged Navier-Stokes (RANS) equations and turbulence models. First of all, during the pre-processing of numerical computation, a sub-domains hybrid meshing scheme is adopted to reduce mesh number and improve mesh quality. Then, four different turbulence models including shear-stress transport (SST) k-w, standard k-w, standard k-ε and Reynolds stress model (RSM) are used to compare and verify the correctness of numerical methods for gas jet from a single aircraft engine. The predicted values are in good agreement with the experimental data, and the distribution and regularity of shock wave, velocity, pressure and temperature of a single aircraft engine are got. The results show that SST k-w turbulence model is more suitable for the numerical simulation of compressible viscous gas jet with high prediction accuracy. Finally, the impact effect of gas jet from two aircraft engines on a jet blast deflector is analyzed based on the above numerical method, not only the flow parameters of gas jet and the interaction regularity between gas jet and the jet blast deflector are got, but also the thermal shock properties and dynamic impact characteristics of gas jet impacting the jet blast deflector are got. So the dangerous activity area of crew and equipments on the flight deck can be predicted qualitatively and quantitatively. The proposed research explores out a correct numerical method for the fluid–solid interaction during the impact process of supersonic gas jet, which provides an effective technical support for design, thermal ablation and structural damage analysis of a new jet blast deflector.

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Blade off that occurs during operation will generate a sudden imbalance excitation and make the rotor become inertially asymmetric, which leads to large instantaneous impact load and induces more complex rotor dynamic phenomena. In order to study the transient dynamic characteristics for complex rotors suffering from blade off, a mathematical model for solving the response of the gas generator rotor in the aero-turboshaft engine is established based on the FE method and DOF condensation, in which the complex structural characteristics, transient impact load, and inertia asymmetry of the rotor are considered. The complex impeller structure is modeled by piecewise linear fitting with cylindrical beam elements and tapered beam elements. Without loss of generality, the modeling method suitable for complex rotors is verified through a general complex test rotor with modal experiments. Based on this, the responses are solved for carrying out parametric studies and an understanding of the transient dynamic characteristics of the rotor under the extreme working conditions of blade off. The results show that the blade off has a great impact effect on the time-domain waveform, frequency components, and rotor orbits. At the instantaneous stage after blade off, the complex motion is composed of synchronous motion and some lower-order natural modes excited by blade off. Although the transient responses with blade off at different rotational speeds have similar time-varying characteristics, the impact factor is sensitive to the rotating speed. Most important is that the parameter of the blade off location will not only have a significant effect on the impact factor, but also on the frequency spectrum. These dynamic characteristics as well as impact effect provide certain guidance for the fault recognition and dynamic analysis to these complex rotors suffering blade off.