Taking 18 large-scale urban agglomerations(UAs)in China as the research objects,this study analyzes the characteristics of the spatiotemporal patterns of carbon emissions in UA areas in China and their impact mechanis...Taking 18 large-scale urban agglomerations(UAs)in China as the research objects,this study analyzes the characteristics of the spatiotemporal patterns of carbon emissions in UA areas in China and their impact mechanisms by citing Moran’s I and geographically weighted regression(GWR).The research findings are as follows:1)obvious differences are found in carbon emissions among different UAs.The cities with higher absolute carbon emissions are mainly distributed in the major cities of the Hohhot-Baotou-Ordos-Yulin UA.2)From 2011 to 2021,the carbon emission levels of China’s UAs grew obviously,but the spatial differences are pronounced,among which the Hohhot-Baotou-Ordos-Yulin UA and others had the highest growth rates.The carbon emission patterns of UAs also present obvious spatial clustering characteristics.The regions with the most obvious growth rates of carbon emissions at the urban scale are mainly distributed in the Hohhot-Baotou-Ordos-Yulin UA and Mid-Yangtze River UA.3)The value of secondary industry(X_(vsi)),number of urban enterprises(X_(nue)),public library holdings(X_(plh)),and urban passenger volume(X_(upv))have an obvious effect on carbon emissions.However,the regression cofficients exhibit obvious spatial variation.Among them,X_(vsi) has an obvious positive effect on carbon emissions,indicating that spatial agglomeration of the real economy substantially increases reginal carbon emission levels.The high X_(nue)regression coefficients are mainly distributed in Harbin-Changchun UA,indicating that the growth of enterprises in this region is still dominated by traditional high-carbon-emission enterprises,the urgent task of low-carbon transformation and upgrading for traditional industries in old industrial regions.The regression coefficients of X_(plh)and X_(upv) are generally negative,suggesting that improving public service facilities and strengthening regional transportation links can help to reduce the level of carbon emissions.展开更多
Water quality parameters such as pH, DO, COD, PQ4 - P, SiO3 - Si, NO2 - N, NO3 -N in the Haikou Bay were monitored respectively before and after Typhoon 9618 occurring on Sep. 18, 1996. Based on the statistics of typh...Water quality parameters such as pH, DO, COD, PQ4 - P, SiO3 - Si, NO2 - N, NO3 -N in the Haikou Bay were monitored respectively before and after Typhoon 9618 occurring on Sep. 18, 1996. Based on the statistics of typhoon in the Haikou Bay and numerical calculation of stormy current, the mechanism of water quality variation caused by typhoon is discussed. The typhoon impact on the Haikou Bay usually appears between July and November, most usually between August and October. The monitoring results before a typhoon were different from that. The stormy wave and windstorm cur-rent stir up the sediment in near-shore bottom and make the bottom water mix with the surface water strongly, specially windstorm current with strong velocity at the head of the bay stirs up higher pollutants sediment near sea area of sewage outfall, and heavy rain with typhoon carries the pollutants from land through the Nandu River to the Haikou Bay, so the contents of COD, PO4 - P, NO4 - N, NO3 ~N, SiO3 after a typhoon are higher than those before. Windstorm current is violent, which makes offshore high DO water exchange more frequently with inner bay water and oxygen in the air dissolves in sea water faster, so DO content after typhoon is higher than that before typhoon. This strong action of water exchange also causes lower pH change before and after the typhoon.展开更多
Deterioration of the physical properties of redbeds is one of the leading causes of geological disasters,engineering problems,and ecological damage.Fabric changes are internal factors leading to the deterioration of p...Deterioration of the physical properties of redbeds is one of the leading causes of geological disasters,engineering problems,and ecological damage.Fabric changes are internal factors leading to the deterioration of physical properties.Existing research on fabric changes in redbeds is qualitative and fuzzy,and their impact on the decline of physical properties needs to be revealed urgently,making the efficient control of redbeds disasters challenging.Therefore,this study focuses on 22 types of redbeds samples and divides them into five classes based on their fabric(composition and structure).Physical property degradation experiments were conducted on different classifications of redbeds during water–rock interaction,and the impact of fabric changes on the degradation of physical properties was analyzed.The results indicate that a linear correlation exists between the internal changes in composition,structure,and physical properties under the action of static water.Moreover,the trend of changes between composition and structure,composition–physical properties,and structure–physical properties shows an exponential regression relationship.Based on this,an action mechanism between compositions such as redbeds,catastrophic minerals,elements,and oxides,as well as the void structure,was proposed,revealing the multifield degradation mechanism of the chemical reactions of the compositions,physical response of the structure,and mechanical reaction of the rock block under the influence of the fabric.The research results can provide a foundation for theoretical research and engineering practice of disaster modes,disaster mechanisms,and prevention and control principles of redbeds disasters.展开更多
High-level interdisciplinary teams are a crucial pillar for research universities aiming to advance toward the Double First-Class Initiative and to foster interdisciplinary integration.This study developed a framework...High-level interdisciplinary teams are a crucial pillar for research universities aiming to advance toward the Double First-Class Initiative and to foster interdisciplinary integration.This study developed a framework for understanding the impact mechanisms and action strategies of high-level interdisciplinary team development through qualitative analysis of nine case teams from two research universities.It found that survival is an antecedent for research teams to engage in interdisciplinary collaboration,with key actors serving as a mediating variable to enhance team development.The interaction of institutions,resources,and culture shapes the development space,which in turn determines the team's strategic space.High-level interdisciplinary teams implement action strategies,including establishing long-term mechanisms,cultivating comparative advantages,and optimizing organizational ecosystems,to achieve rapid breakthroughs.To advance the high-quality development of interdisciplinary teams,it is essential to enhance interdisciplinary integration and implement targeted,systemic,organizational,and fundamental measures across multiple dimensions,such as resources,institutions,and culture.These efforts would facilitate a multidimensional environment conducive to interdisciplinaryteams'development.展开更多
As a necessary factor for a successful business,entrepreneurial spirit is an important means for enterprises to survive in the unstable environment of fierce competition. Under the circumstance of mass entrepreneurshi...As a necessary factor for a successful business,entrepreneurial spirit is an important means for enterprises to survive in the unstable environment of fierce competition. Under the circumstance of mass entrepreneurship and innovation,a large number of small and medium-sized private enterprises have emerged in all walks of life in China. This paper examines the differences in the definition of entrepreneurial spirit by different scholars,the influence of Chinese entrepreneurship on the development of small and medium-sized private enterprises,the origin of the spirit of private entrepreneurs with Chinese characteristics,and the disadvantages of the spirit of small and medium-sized private entrepreneurs in China. It is necessary to further improve entrepreneurial spirit to contribute to the development of small and medium-sized private enterprises and help China to build the national economic system.展开更多
In this study, tropical cyclone data from China Meteorological Administration （CMA） and the ECMWF reanalysis data for the period 1958-2001 was used to propose a possible mechanism for the impacts of air- sea interac...In this study, tropical cyclone data from China Meteorological Administration （CMA） and the ECMWF reanalysis data for the period 1958-2001 was used to propose a possible mechanism for the impacts of air- sea interaction on the activity of tropical cyclones （TCs） affecting China. The frequency of TCs affecting China over past 40 years has trended downward, while during the same period, the air sea interaction in the two key areas of the Pacific region has significantly weakened. Our diagnoses and simulations suggest that air sea interactions in the central North Pacific tropics and subtropics （Area 1） have an important role in adjusting typhoon activities in the Northwest Pacific in general, and especially in TC activity affecting China. On the contrary, impacts of the air-sea interaction in the eastern part of the South Pacific tropics （Area 2） were found to be rather limited. As both observational analysis and modeling studies show that, in the past four decades and beyond, the weakening trend of the latent heat released from Area 1 matched well with the decreasing Northwest Pacific TC frequency derived from CMA datasets. Results also showed that the weakening trend of latent heat flux in the area was most likely due to the decreasing TC frequency over the Northwest Pacific, including those affecting China. Although our preliminary analysis revealed a possible mechanism through which the air sea interaction may adjust the genesis conditions for TCs, which eventually affect China, other relevant questions, such as how TC tracks and impacts are affected by these trends, remain unanswered. Further in-depth investigations are required.展开更多
This paper discusses ancestral hall architecture within the context of the Cantonese folk lineage in the Pearl River Delta.Using a typological research approach and chronological analysis,various factors that have inf...This paper discusses ancestral hall architecture within the context of the Cantonese folk lineage in the Pearl River Delta.Using a typological research approach and chronological analysis,various factors that have influenced the evolution of ancestral hall architecture are analyzed.The study specifically investigates the features of ancestral halls during the Ming and Qing dynasties.Three periods of ancient China are analyzed:The transition from Ming to Qing,the mid-Qing dynasty,and the late Qing dynasty.The variables of each period and how they influence the evolution of architectural typological features are identified.Based on our analysis,architectural features are related to economic and social factors,materials available,and craftsmanship of the construction workers.展开更多
Aim:The oxidized low-density lipoprotein(OxLDL) plays an important role in atherosclerosis yet it remains unclear if it damages circulating erythrocytes. Method: In this study。
The microstructure and mechanical properties of multi-layer multi-pass TIG welded joints of Al-Zn-Mg alloy plates were studied.The phase constituent and microstructure of different regions of the welded joints were ch...The microstructure and mechanical properties of multi-layer multi-pass TIG welded joints of Al-Zn-Mg alloy plates were studied.The phase constituent and microstructure of different regions of the welded joints were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),transmission electron microscopy(TEM)and energy disperse spectrum(EDS),while the mechanical properties were evaluated according to the impact test.A dispersively distributed spherical and needle-likeη(MgZn2)phase was obtained in the welding seam.The phase composition of the heat-affected zone(HAZ)wasα(Al)+η(MgZn2)+Al6Mn,and there were a large number of dispersively precipitated nanoscale particles.The welded joint zone had the highest impact toughness as compared with the other parts of the joint.The MgZn2 phase in the weld zone contributed to the improved toughness of the joint.Al2 MgCu phase in HAZ was proven to act as a crack source during fracture.展开更多
Impact flash occurs when objects collide at supersonic speeds and can be used for real-time damage assessment when weapons rely on kinetic energy to destroy targets.However,the mechanism of impact flash remains unclea...Impact flash occurs when objects collide at supersonic speeds and can be used for real-time damage assessment when weapons rely on kinetic energy to destroy targets.However,the mechanism of impact flash remains unclear.A series of impact flash experiments of flat-head long-rod projectiles impacting thin target plates were performed with a two-stage light gas gun.The impact flash spectra for 6061 aluminum at 1.3e3.2 km/s collision speeds were recorded with a high-speed camera,a photoelectric sensor,and a time-resolved spectrometer.The intensity of the impact flash exhibited a pulse characteristic with time.The intensity(I)increased with impact velocity(V0)according to IfVn 0,where n?4.41 for V0>2 km/s.However,for V0<2 km/s,n?2.21,and the intense flash duration is an order of magnitude less than that of higher V0.When V0>2 km/s,a continuous spectrum(thermal radiation background)was observed and increased in intensity with V0.However,for V0<2 km/s,only atomic line spectra were detected.There was no aluminum spectral lines for V0<2 km/s,which indicated that it had not been vaporized.The initial intense flash was emission from excited and ionized ambient gases near the impact surface,and had little relationship with shock temperature rise,indicating a new mechanism of impact flash.展开更多
A74-mm-diameter Split Hopkinson pressure bar was used to carry out the dynamic compression experiment of concrete made of desert sand.The dynamic failure processes of concrete different in specimen size,impact velocit...A74-mm-diameter Split Hopkinson pressure bar was used to carry out the dynamic compression experiment of concrete made of desert sand.The dynamic failure processes of concrete different in specimen size,impact velocity,desert sand replacement ratio,size and volume content of coarse aggregate were simulated.Research results showed that concrete made of desert sand had size-effect and was rate-dependent.The peak stress of concrete made of desert sand declined with the minimum size of coarse aggregate.However,the peak stress of concrete made of desert sand increased first,and then declined with the volume content and maximum size of coarse aggregate.展开更多
A continuum damage mechanics (CDM) meso-model was derived for both intraply and interply progressive failure behaviors of a 2D woven-fabric composite laminate under a transversely low velocity impact.An in-plane aniso...A continuum damage mechanics (CDM) meso-model was derived for both intraply and interply progressive failure behaviors of a 2D woven-fabric composite laminate under a transversely low velocity impact.An in-plane anisotropic damage constitutive model of a 2D woven composite ply was derived based on CDM within a thermodynamic framework,an elastic constitutive model with damage for the fibre directions and an elastic-plastic constitutive model with damage for the shear direction.The progressive failure behavior of a 2D woven composite ply is determined by the damage internal variables in different directions with appropriate damage evolution equations.The interface between two adjacent 2D woven composite plies with different ply orientations was modeled by a traction-separation law based interface element.An isotropic damage constitutive law with CDM properties was used for the interface element,and a damage surface which combines stress and fracture mechanics failure criteria was employed to derive the damage initiation and evolution for the mixed-mode delamination of the interface elements.Numerical analysis and experiments were both carried out on a 2D woven glass fibre/epoxy laminate.The simulation results are in agreement with the experimental counterparts,verifying the progressive failure model of a woven composite laminate.The proposed model will enhance the understanding of dynamic deformation and progressive failure behavior of composite laminate structures in the low velocity impact process.展开更多
Transporting hatching eggs from Hungary and incubating them abroad revealed lower hatchability compared to when the eggs were incubated in Hungary. Following transport, there were higher embryo losses and, notably, mo...Transporting hatching eggs from Hungary and incubating them abroad revealed lower hatchability compared to when the eggs were incubated in Hungary. Following transport, there were higher embryo losses and, notably, more malformed embryos. The aim of these initial trials was to determine if a testing device （crazy fit massage machine （CFM machine）） was able to replicate and model the mechanical impacts experienced during transport and reproduce the reduction in hatchability and increase the level of malformed embryos as observed in commercial practice. Tinytag~ high sensitivity shock and vibration loggers were used to monitor the impacts under field and trial conditions. Applying single 10 min treatments on the CFM machine, which used the same frequency （10-30 Hz） as the eggs experience under field conditions, induced the negative effect of transport, and lower hatching results were experienced. Three trials were conducted. Treated eggs in Trials 1 and 2 received automatically and periodical changing vibration in a range between 10-30 Hz for 10 min while in Trial 3 two different levels of impact were applied at 20 Hz and 30 Hz, respectively. Hatchability decreased due to the treatment significatly only in Trial 3. Significant differences were also detected in early dead levels in Trials 2 and 3 and the occurrences of malformation in Trials 1 and 3. All these results are in accordance with the field experience. Thus, the trials which examined the equipment were able to produce mechanical impacts that were repeatable in order to set up statistically reliable trials on hatching eggs.展开更多
Snowfall is the primary form of cold-season precipitation over the Tibetan Plateau(TP),crucial for the maintenance of glaciers and snow cover,affecting regional climates and water resources availability.Through an int...Snowfall is the primary form of cold-season precipitation over the Tibetan Plateau(TP),crucial for the maintenance of glaciers and snow cover,affecting regional climates and water resources availability.Through an integrative analysis of observations,numerical simulations,and statistical analyses,we found that the spatiotemporal distribution of snowfall across the TP is significantly influenced by black carbon(BC)aerosols from South Asia and the TP.BC affects the snowfall process through multiple mechanisms.Specifically,BC significantly raises atmospheric temperature over the TP,thereby reducing snowfall,particularly in the central TP during autumn,with reductions reaching approximately−9 mm water equivalent month−1.Moreover,BC enhances cold-season moisture transport from the Bay of Bengal,increasing moisture flux in the southeastern TP and thereby augmenting snowfall in that area by up to 5 mm water equivalent month−1.This study elucidates the complex impact of BC on the spatial–temporal snowfall patterns across the TP and provides important insights into the sustainable development of water resources in the region amid ongoing climate change.展开更多
The high-speed multi-cycle impact and speed, load fluctuant characteristics of a kind of narrow-width automotive engine oil-pump chain 06BN-1 are studied through engine assembly and road-drive tests to satisfy the lig...The high-speed multi-cycle impact and speed, load fluctuant characteristics of a kind of narrow-width automotive engine oil-pump chain 06BN-1 are studied through engine assembly and road-drive tests to satisfy the light-weight demand of engine. The worn surface morphologies of rubbing area between pin, bush and roller are also analyzed based on scanning electron microscope. The results show that the main wear mechanism of automotive engine oil-pump chain is fatigue wear, and it＇s failure mechanism is the forming, extending and flaking of cracks on top layer of pin and bush. Pin and bush both occurred cycle-soften phenomenon, and roller occurred cycle-harden. Fretting wear is one of the most important ＂fall to pieces＂ failure causes of automotive chain. Ensuring sufficient strength and plasticity of roller, as well as adopting suitable shaping technology are the effective methods to increase its resistance to multi-cycle impact.展开更多
Based on the shear wave tracing(SWT) technique proposed by Tang Z P, particle velocity gauge and the dual internal measurement for pressure and shear waves (IMPS) system are applied to investigate the responses of fib...Based on the shear wave tracing(SWT) technique proposed by Tang Z P, particle velocity gauge and the dual internal measurement for pressure and shear waves (IMPS) system are applied to investigate the responses of fiber reinforced cement subjected to impact loading. Series of experiments are conducted. The results show that there exist four critical points, A, B, C, D, in p-V Hugoniot curves. They correspond to the Hugoniot elastic limit (HEL) of the material, the critical point for shear strength limit and transition from damage state to failure state, void collapse, and solid compression, respectively. The critical point B is difficult to be aware of and never reported. However, it can be clearly disclosed with SWT method. Based on the analyses of shear strength, it can be concluded that the transversal wave, especially the unloading transversal wave, is especially important for the dynamic damage investigation of brittle materials.展开更多
Empowering the value realization of ecological products with a digital economy is an important path for achieving the transformation of“two mountains”and the construction of ecological civilization.Based on the pane...Empowering the value realization of ecological products with a digital economy is an important path for achieving the transformation of“two mountains”and the construction of ecological civilization.Based on the panel data of 30 provinces in China from 2011 to 2022,a fixed-effects model was used to empirically test the impact,heterogeneity and mechanism of the effects of the digital economy on the value realization of ecological products.This analysis revealed three key findings.(1)The digital economy has a significant driving effect on improving the ability to realize the value of ecological products,and this effect is still applicable in a variety of robustness tests such as shrinking the years,replacing explanatory variables,and endogeneity tests.(2)The rise of the digital economy affects the value realization of ecological products to different degrees in different regions,especially in the eastern region,while the effect in the central region is not obvious.(3)The analysis of mechanistic variables indicated that the digital economy has an impact on the value realization of ecological products through the development of green finance and government revenue.Therefore,the government should design differentiated and multi-level support policies for the realization of ecological product value according to the heterogeneity of natural resources,ecological potential and the levels of digital economy development in different regions,and it should strengthen the control of non-environmental protection behaviors of the enterprises.Enterprises should accelerate the digital transformation of the entire production,distribution,circulation and consumption chain of ecological products,and actively develop financial products and services that meet the characteristics and needs of ecological products.展开更多
To represent a loose lap joint, a beam impacting four springs with gaps is modeled. Modal analysis with base excitation is solved, and time histories of contact points are closely monitored. Using the impulse during s...To represent a loose lap joint, a beam impacting four springs with gaps is modeled. Modal analysis with base excitation is solved, and time histories of contact points are closely monitored. Using the impulse during steady state response, six influential parameters are studied： damping ratio, contact stiffness, intermediate contact position, gap, excitation amplitude and beam height. For all parameters, the system response is highly controlled by modes with two contacting springs. Each parameter＇s effect on system response is presented including unstable regions, unique trend behaviours result. Recommendations for structural designers are also noted.展开更多
基金Under the auspices of the National Social Science Foundation of China(No.23BJL133)。
文摘Taking 18 large-scale urban agglomerations(UAs)in China as the research objects,this study analyzes the characteristics of the spatiotemporal patterns of carbon emissions in UA areas in China and their impact mechanisms by citing Moran’s I and geographically weighted regression(GWR).The research findings are as follows:1)obvious differences are found in carbon emissions among different UAs.The cities with higher absolute carbon emissions are mainly distributed in the major cities of the Hohhot-Baotou-Ordos-Yulin UA.2)From 2011 to 2021,the carbon emission levels of China’s UAs grew obviously,but the spatial differences are pronounced,among which the Hohhot-Baotou-Ordos-Yulin UA and others had the highest growth rates.The carbon emission patterns of UAs also present obvious spatial clustering characteristics.The regions with the most obvious growth rates of carbon emissions at the urban scale are mainly distributed in the Hohhot-Baotou-Ordos-Yulin UA and Mid-Yangtze River UA.3)The value of secondary industry(X_(vsi)),number of urban enterprises(X_(nue)),public library holdings(X_(plh)),and urban passenger volume(X_(upv))have an obvious effect on carbon emissions.However,the regression cofficients exhibit obvious spatial variation.Among them,X_(vsi) has an obvious positive effect on carbon emissions,indicating that spatial agglomeration of the real economy substantially increases reginal carbon emission levels.The high X_(nue)regression coefficients are mainly distributed in Harbin-Changchun UA,indicating that the growth of enterprises in this region is still dominated by traditional high-carbon-emission enterprises,the urgent task of low-carbon transformation and upgrading for traditional industries in old industrial regions.The regression coefficients of X_(plh)and X_(upv) are generally negative,suggesting that improving public service facilities and strengthening regional transportation links can help to reduce the level of carbon emissions.
基金This study was supported by the National Natural Science Foundation of China under contrast No. 49966001.
文摘Water quality parameters such as pH, DO, COD, PQ4 - P, SiO3 - Si, NO2 - N, NO3 -N in the Haikou Bay were monitored respectively before and after Typhoon 9618 occurring on Sep. 18, 1996. Based on the statistics of typhoon in the Haikou Bay and numerical calculation of stormy current, the mechanism of water quality variation caused by typhoon is discussed. The typhoon impact on the Haikou Bay usually appears between July and November, most usually between August and October. The monitoring results before a typhoon were different from that. The stormy wave and windstorm cur-rent stir up the sediment in near-shore bottom and make the bottom water mix with the surface water strongly, specially windstorm current with strong velocity at the head of the bay stirs up higher pollutants sediment near sea area of sewage outfall, and heavy rain with typhoon carries the pollutants from land through the Nandu River to the Haikou Bay, so the contents of COD, PO4 - P, NO4 - N, NO3 ~N, SiO3 after a typhoon are higher than those before. Windstorm current is violent, which makes offshore high DO water exchange more frequently with inner bay water and oxygen in the air dissolves in sea water faster, so DO content after typhoon is higher than that before typhoon. This strong action of water exchange also causes lower pH change before and after the typhoon.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Numbers:42293354,42277131,42293351,42293355 and 42293350)。
文摘Deterioration of the physical properties of redbeds is one of the leading causes of geological disasters,engineering problems,and ecological damage.Fabric changes are internal factors leading to the deterioration of physical properties.Existing research on fabric changes in redbeds is qualitative and fuzzy,and their impact on the decline of physical properties needs to be revealed urgently,making the efficient control of redbeds disasters challenging.Therefore,this study focuses on 22 types of redbeds samples and divides them into five classes based on their fabric(composition and structure).Physical property degradation experiments were conducted on different classifications of redbeds during water–rock interaction,and the impact of fabric changes on the degradation of physical properties was analyzed.The results indicate that a linear correlation exists between the internal changes in composition,structure,and physical properties under the action of static water.Moreover,the trend of changes between composition and structure,composition–physical properties,and structure–physical properties shows an exponential regression relationship.Based on this,an action mechanism between compositions such as redbeds,catastrophic minerals,elements,and oxides,as well as the void structure,was proposed,revealing the multifield degradation mechanism of the chemical reactions of the compositions,physical response of the structure,and mechanical reaction of the rock block under the influence of the fabric.The research results can provide a foundation for theoretical research and engineering practice of disaster modes,disaster mechanisms,and prevention and control principles of redbeds disasters.
基金funded by the National Social Sciences Fund of China in 2022,the general program“Research on Evolutionary Mechanisms and Cultivation Strategies for High-Level Interdisciplinary Teams in Universities”(No.BIA220102).
文摘High-level interdisciplinary teams are a crucial pillar for research universities aiming to advance toward the Double First-Class Initiative and to foster interdisciplinary integration.This study developed a framework for understanding the impact mechanisms and action strategies of high-level interdisciplinary team development through qualitative analysis of nine case teams from two research universities.It found that survival is an antecedent for research teams to engage in interdisciplinary collaboration,with key actors serving as a mediating variable to enhance team development.The interaction of institutions,resources,and culture shapes the development space,which in turn determines the team's strategic space.High-level interdisciplinary teams implement action strategies,including establishing long-term mechanisms,cultivating comparative advantages,and optimizing organizational ecosystems,to achieve rapid breakthroughs.To advance the high-quality development of interdisciplinary teams,it is essential to enhance interdisciplinary integration and implement targeted,systemic,organizational,and fundamental measures across multiple dimensions,such as resources,institutions,and culture.These efforts would facilitate a multidimensional environment conducive to interdisciplinaryteams'development.
基金Supported by Special Youth Project"A Comparative Study on the Cultivation Mode of Innovative Entrepreneurship Talents in China and South Korea"(120-1452226)
文摘As a necessary factor for a successful business,entrepreneurial spirit is an important means for enterprises to survive in the unstable environment of fierce competition. Under the circumstance of mass entrepreneurship and innovation,a large number of small and medium-sized private enterprises have emerged in all walks of life in China. This paper examines the differences in the definition of entrepreneurial spirit by different scholars,the influence of Chinese entrepreneurship on the development of small and medium-sized private enterprises,the origin of the spirit of private entrepreneurs with Chinese characteristics,and the disadvantages of the spirit of small and medium-sized private entrepreneurs in China. It is necessary to further improve entrepreneurial spirit to contribute to the development of small and medium-sized private enterprises and help China to build the national economic system.
基金supported by the R&D Special Fund for Public Welfare Industry(meteorology)(Grant No.GYHY200806009)the National Natural Science Foundation of China(GrantNos.40775046,40730106)
文摘In this study, tropical cyclone data from China Meteorological Administration （CMA） and the ECMWF reanalysis data for the period 1958-2001 was used to propose a possible mechanism for the impacts of air- sea interaction on the activity of tropical cyclones （TCs） affecting China. The frequency of TCs affecting China over past 40 years has trended downward, while during the same period, the air sea interaction in the two key areas of the Pacific region has significantly weakened. Our diagnoses and simulations suggest that air sea interactions in the central North Pacific tropics and subtropics （Area 1） have an important role in adjusting typhoon activities in the Northwest Pacific in general, and especially in TC activity affecting China. On the contrary, impacts of the air-sea interaction in the eastern part of the South Pacific tropics （Area 2） were found to be rather limited. As both observational analysis and modeling studies show that, in the past four decades and beyond, the weakening trend of the latent heat released from Area 1 matched well with the decreasing Northwest Pacific TC frequency derived from CMA datasets. Results also showed that the weakening trend of latent heat flux in the area was most likely due to the decreasing TC frequency over the Northwest Pacific, including those affecting China. Although our preliminary analysis revealed a possible mechanism through which the air sea interaction may adjust the genesis conditions for TCs, which eventually affect China, other relevant questions, such as how TC tracks and impacts are affected by these trends, remain unanswered. Further in-depth investigations are required.
文摘This paper discusses ancestral hall architecture within the context of the Cantonese folk lineage in the Pearl River Delta.Using a typological research approach and chronological analysis,various factors that have influenced the evolution of ancestral hall architecture are analyzed.The study specifically investigates the features of ancestral halls during the Ming and Qing dynasties.Three periods of ancient China are analyzed:The transition from Ming to Qing,the mid-Qing dynasty,and the late Qing dynasty.The variables of each period and how they influence the evolution of architectural typological features are identified.Based on our analysis,architectural features are related to economic and social factors,materials available,and craftsmanship of the construction workers.
基金supported by National Natural Science Foundation of China(NSFC10572159)supported by "111 Project" entitled "Biomechanics&Tissue Repair Engineering"(No.:B06023)Chongqing Science&Technology Council(CSTC 2006ba5010)
文摘Aim:The oxidized low-density lipoprotein(OxLDL) plays an important role in atherosclerosis yet it remains unclear if it damages circulating erythrocytes. Method: In this study。
基金Project(ZR2016EEQ03) supported by the Shandong Province Natural Science Foundation,ChinaProject(2018M641822) supported by the China Postdoctoral Science Foundation-General ProgramProject(HIT.NSRIF.201703) supported by the Natural Scientific Research Innovation Foundation in HIT,China
文摘The microstructure and mechanical properties of multi-layer multi-pass TIG welded joints of Al-Zn-Mg alloy plates were studied.The phase constituent and microstructure of different regions of the welded joints were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD),transmission electron microscopy(TEM)and energy disperse spectrum(EDS),while the mechanical properties were evaluated according to the impact test.A dispersively distributed spherical and needle-likeη(MgZn2)phase was obtained in the welding seam.The phase composition of the heat-affected zone(HAZ)wasα(Al)+η(MgZn2)+Al6Mn,and there were a large number of dispersively precipitated nanoscale particles.The welded joint zone had the highest impact toughness as compared with the other parts of the joint.The MgZn2 phase in the weld zone contributed to the improved toughness of the joint.Al2 MgCu phase in HAZ was proven to act as a crack source during fracture.
基金This work was supported by the National Key R&D Programof China(Grant No.2016YFC0801204)the National Programon Key Basic Research Project of China(973 Program,Grant No.613312).
文摘Impact flash occurs when objects collide at supersonic speeds and can be used for real-time damage assessment when weapons rely on kinetic energy to destroy targets.However,the mechanism of impact flash remains unclear.A series of impact flash experiments of flat-head long-rod projectiles impacting thin target plates were performed with a two-stage light gas gun.The impact flash spectra for 6061 aluminum at 1.3e3.2 km/s collision speeds were recorded with a high-speed camera,a photoelectric sensor,and a time-resolved spectrometer.The intensity of the impact flash exhibited a pulse characteristic with time.The intensity(I)increased with impact velocity(V0)according to IfVn 0,where n?4.41 for V0>2 km/s.However,for V0<2 km/s,n?2.21,and the intense flash duration is an order of magnitude less than that of higher V0.When V0>2 km/s,a continuous spectrum(thermal radiation background)was observed and increased in intensity with V0.However,for V0<2 km/s,only atomic line spectra were detected.There was no aluminum spectral lines for V0<2 km/s,which indicated that it had not been vaporized.The initial intense flash was emission from excited and ionized ambient gases near the impact surface,and had little relationship with shock temperature rise,indicating a new mechanism of impact flash.
基金Project supported by the National Natural Science Foundation of China(Nos.51368048 and 11162015)
文摘A74-mm-diameter Split Hopkinson pressure bar was used to carry out the dynamic compression experiment of concrete made of desert sand.The dynamic failure processes of concrete different in specimen size,impact velocity,desert sand replacement ratio,size and volume content of coarse aggregate were simulated.Research results showed that concrete made of desert sand had size-effect and was rate-dependent.The peak stress of concrete made of desert sand declined with the minimum size of coarse aggregate.However,the peak stress of concrete made of desert sand increased first,and then declined with the volume content and maximum size of coarse aggregate.
文摘A continuum damage mechanics (CDM) meso-model was derived for both intraply and interply progressive failure behaviors of a 2D woven-fabric composite laminate under a transversely low velocity impact.An in-plane anisotropic damage constitutive model of a 2D woven composite ply was derived based on CDM within a thermodynamic framework,an elastic constitutive model with damage for the fibre directions and an elastic-plastic constitutive model with damage for the shear direction.The progressive failure behavior of a 2D woven composite ply is determined by the damage internal variables in different directions with appropriate damage evolution equations.The interface between two adjacent 2D woven composite plies with different ply orientations was modeled by a traction-separation law based interface element.An isotropic damage constitutive law with CDM properties was used for the interface element,and a damage surface which combines stress and fracture mechanics failure criteria was employed to derive the damage initiation and evolution for the mixed-mode delamination of the interface elements.Numerical analysis and experiments were both carried out on a 2D woven glass fibre/epoxy laminate.The simulation results are in agreement with the experimental counterparts,verifying the progressive failure model of a woven composite laminate.The proposed model will enhance the understanding of dynamic deformation and progressive failure behavior of composite laminate structures in the low velocity impact process.
文摘Transporting hatching eggs from Hungary and incubating them abroad revealed lower hatchability compared to when the eggs were incubated in Hungary. Following transport, there were higher embryo losses and, notably, more malformed embryos. The aim of these initial trials was to determine if a testing device （crazy fit massage machine （CFM machine）） was able to replicate and model the mechanical impacts experienced during transport and reproduce the reduction in hatchability and increase the level of malformed embryos as observed in commercial practice. Tinytag~ high sensitivity shock and vibration loggers were used to monitor the impacts under field and trial conditions. Applying single 10 min treatments on the CFM machine, which used the same frequency （10-30 Hz） as the eggs experience under field conditions, induced the negative effect of transport, and lower hatching results were experienced. Three trials were conducted. Treated eggs in Trials 1 and 2 received automatically and periodical changing vibration in a range between 10-30 Hz for 10 min while in Trial 3 two different levels of impact were applied at 20 Hz and 30 Hz, respectively. Hatchability decreased due to the treatment significatly only in Trial 3. Significant differences were also detected in early dead levels in Trials 2 and 3 and the occurrences of malformation in Trials 1 and 3. All these results are in accordance with the field experience. Thus, the trials which examined the equipment were able to produce mechanical impacts that were repeatable in order to set up statistically reliable trials on hatching eggs.
基金supported by the National Natural Science Foundation of China(42071096,42275045)Foundation from Gansu Provincial Department of Education(2024A-200,2024QB-054)+3 种基金West Light Foundation of The Chinese Academy of Sciences(xbzg-zdsys-202306)the Science Fund for Creative Research Groups of Gansu Province(Grant No.23JRRA567)Outstanding Youth Fund of Gansu Province(24JRRA078)Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0605).
文摘Snowfall is the primary form of cold-season precipitation over the Tibetan Plateau(TP),crucial for the maintenance of glaciers and snow cover,affecting regional climates and water resources availability.Through an integrative analysis of observations,numerical simulations,and statistical analyses,we found that the spatiotemporal distribution of snowfall across the TP is significantly influenced by black carbon(BC)aerosols from South Asia and the TP.BC affects the snowfall process through multiple mechanisms.Specifically,BC significantly raises atmospheric temperature over the TP,thereby reducing snowfall,particularly in the central TP during autumn,with reductions reaching approximately−9 mm water equivalent month−1.Moreover,BC enhances cold-season moisture transport from the Bay of Bengal,increasing moisture flux in the southeastern TP and thereby augmenting snowfall in that area by up to 5 mm water equivalent month−1.This study elucidates the complex impact of BC on the spatial–temporal snowfall patterns across the TP and provides important insights into the sustainable development of water resources in the region amid ongoing climate change.
基金This project is supported by National Innovation Foundation for Technology Based Firms, China (No. 01C26213300872)
文摘The high-speed multi-cycle impact and speed, load fluctuant characteristics of a kind of narrow-width automotive engine oil-pump chain 06BN-1 are studied through engine assembly and road-drive tests to satisfy the light-weight demand of engine. The worn surface morphologies of rubbing area between pin, bush and roller are also analyzed based on scanning electron microscope. The results show that the main wear mechanism of automotive engine oil-pump chain is fatigue wear, and it＇s failure mechanism is the forming, extending and flaking of cracks on top layer of pin and bush. Pin and bush both occurred cycle-soften phenomenon, and roller occurred cycle-harden. Fretting wear is one of the most important ＂fall to pieces＂ failure causes of automotive chain. Ensuring sufficient strength and plasticity of roller, as well as adopting suitable shaping technology are the effective methods to increase its resistance to multi-cycle impact.
文摘Based on the shear wave tracing(SWT) technique proposed by Tang Z P, particle velocity gauge and the dual internal measurement for pressure and shear waves (IMPS) system are applied to investigate the responses of fiber reinforced cement subjected to impact loading. Series of experiments are conducted. The results show that there exist four critical points, A, B, C, D, in p-V Hugoniot curves. They correspond to the Hugoniot elastic limit (HEL) of the material, the critical point for shear strength limit and transition from damage state to failure state, void collapse, and solid compression, respectively. The critical point B is difficult to be aware of and never reported. However, it can be clearly disclosed with SWT method. Based on the analyses of shear strength, it can be concluded that the transversal wave, especially the unloading transversal wave, is especially important for the dynamic damage investigation of brittle materials.
基金The National Natural Science Foundation of China(41961046)。
文摘Empowering the value realization of ecological products with a digital economy is an important path for achieving the transformation of“two mountains”and the construction of ecological civilization.Based on the panel data of 30 provinces in China from 2011 to 2022,a fixed-effects model was used to empirically test the impact,heterogeneity and mechanism of the effects of the digital economy on the value realization of ecological products.This analysis revealed three key findings.(1)The digital economy has a significant driving effect on improving the ability to realize the value of ecological products,and this effect is still applicable in a variety of robustness tests such as shrinking the years,replacing explanatory variables,and endogeneity tests.(2)The rise of the digital economy affects the value realization of ecological products to different degrees in different regions,especially in the eastern region,while the effect in the central region is not obvious.(3)The analysis of mechanistic variables indicated that the digital economy has an impact on the value realization of ecological products through the development of green finance and government revenue.Therefore,the government should design differentiated and multi-level support policies for the realization of ecological product value according to the heterogeneity of natural resources,ecological potential and the levels of digital economy development in different regions,and it should strengthen the control of non-environmental protection behaviors of the enterprises.Enterprises should accelerate the digital transformation of the entire production,distribution,circulation and consumption chain of ecological products,and actively develop financial products and services that meet the characteristics and needs of ecological products.
文摘To represent a loose lap joint, a beam impacting four springs with gaps is modeled. Modal analysis with base excitation is solved, and time histories of contact points are closely monitored. Using the impulse during steady state response, six influential parameters are studied： damping ratio, contact stiffness, intermediate contact position, gap, excitation amplitude and beam height. For all parameters, the system response is highly controlled by modes with two contacting springs. Each parameter＇s effect on system response is presented including unstable regions, unique trend behaviours result. Recommendations for structural designers are also noted.
