This study examined the relationship between inclusive leadership and subordinates’upward voice,focusing on the mediating role of psychological safety and the moderating role of collectivism.Data were collected from ...This study examined the relationship between inclusive leadership and subordinates’upward voice,focusing on the mediating role of psychological safety and the moderating role of collectivism.Data were collected from 284 subordinates and supervisors across 11 organizations in China in three cross-lagged waves.Structural equation modeling results indicated that inclusive leadership was associated with subordinates’upward voice via psychological safety.Moreover,collectivism strengthens the association between inclusive leadership and upward voice via psychological safety,leading to a higher upward voice.These findings highlight the importance of inclusive leadership in fostering an environment that promotes open communication and psychological safety between supervisors and subordinates,ultimately enhancing workplace health and well-being.The implications of these findings suggest that management practices should cultivate inclusive leadership behaviors for enhancing psychological safety,and encouraging subordinates to voice their opinions for the overall success of the organization.展开更多
Background:Platform algorithms driving content presentation are profoundly shaping the experience of younger users.While prior research has examined anxiety stemming from young adults’social media usage,the link betw...Background:Platform algorithms driving content presentation are profoundly shaping the experience of younger users.While prior research has examined anxiety stemming from young adults’social media usage,the link between upward social comparison and anxiety remains unclear.This study aims to investigate the mediating role of upward social comparison in this relationship and determine the moderating role of psychological resilience.Methods:A cross-sectional survey was conducted among 562 young Chinese adults aged 18–35(53%female).Data were collected via an online questionnaire employing validated measurement instruments,including scales for social media usage patterns,upward comparator behaviour(INCOM),anxiety levels(GAD-7),and psychological resilience(RSA).Correlation analysis,mediation analysis,and moderation analysis were conducted using SPSS 29.0.Results:As predicted,the results indicate that upward social comparison mediates the relationship between both active(β=−0.11,95%CI=[−0.15,−0.08])and passive(β=0.11,95%CI=[0.07,0.15])social media use and anxiety.Furthermore,psychological resilience(β_(low)=0.10,95%CI=[0.06,0.14];β_(high)=0.05,95%CI=[0.01,0.09])moderated the indirect effect of passive social media use on anxiety through upward social comparison.Conclusion:The findings indicate that upward social comparison significantly influences the anxiety experienced by young social media users,with psychological resilience playing a crucial moderating role.These results offer valuable insights for optimizing content recommendation algorithms on social media platforms to better support young adults’mental health.展开更多
Xinli district of Sanshandao Gold Mine is the first subsea metal mine in China.To achieve 6 kt/d production capacity under the premise of safe mining,high-intensity mining might destroy the in-situ stress filed and th...Xinli district of Sanshandao Gold Mine is the first subsea metal mine in China.To achieve 6 kt/d production capacity under the premise of safe mining,high-intensity mining might destroy the in-situ stress filed and the stability of rockmass.According to sampling and testing of ore-rock and backfill and in-situ stress field measurement,safety factor method calculation model based on stress-strain strength reduction at arbitrary points and Mohr-Coulomb yield criterion was established and limit displacement subsidence values under the safety factor of different limit stoping steps were calculated.The results from three years in-situ mining and strata movement monitoring using multi-point displacements meter showed that the lower settlement frame stope hierarchical level filling mining method,mining sequence are reasonable and rockmass stability evaluation using safety factor method,in-situ real-time monitoring can provide the technical foundation for the safety of seabed mining.展开更多
There has been a long tradition in the history of Hungarian intellectuals that dates as far back as the 1930s.It became well-known as the clash between the“populist”(nepies)and“urbanite”(urbanus)camps as two facti...There has been a long tradition in the history of Hungarian intellectuals that dates as far back as the 1930s.It became well-known as the clash between the“populist”(nepies)and“urbanite”(urbanus)camps as two factions of the intellectual classes or status groups.However,the author’s historical investigations show that this clash originated during the first reform period of Hungarian history(1830-1848),when the“Centralists”under the leadership of József Eötvös confronted the“Municipalists”whose leading figure was Lajos Kossuth.The former group represented the Western Europe oriented faction,who heavily called into question the county system,while the members of the latter group warranted it as the bulwark of the Hungarian constitution.The conflict was renewed between the two world wars as“westernizing”urbanites opposed the“Magyar”-oriented populists.Also,after the regime change in the 1990s,this old clash posited itself politically first as the strife between the Hungarian Democratic Forum and the Free Democrats and later on it got the form of a European-oriented Leftist-Liberal wing facing the moderate Right.The desperate struggle between the two political wings appeared at the local level as well.The author describes a paradigmatic case of the overall contradiction in a case study.During the local elections in a Hungarian village the post-communist mayor was forced to run against a traditionally religious mayor,while the entire village population,including civil society,followed the desperate clash up to an unserviceable stage.At this point,a third mayor candidate stepped in competing with both former enemies and won the exceptional election.The new mayor transcended both the post-communist era and the oppositional mayor of traditional religious background,for as the great-grand child of a landowner in the period preceding the Second World War who was persecuted in the Communist era;this mayor restituted the continuity with the ancient landowner class.And at the same time,while jettisoning the old-fashioned religion,she exhibited a certain attachment to a new type,as it were,a postmodern religiosity.展开更多
It is one of the most effective ways to use laboratory long air gap discharges for investigating the fundamental process involved in the lightning strike.During the 1960s and the 1970s,the electro-geometrical method(E...It is one of the most effective ways to use laboratory long air gap discharges for investigating the fundamental process involved in the lightning strike.During the 1960s and the 1970s,the electro-geometrical method(EGM)and the rolling sphere method were developed base on the breakdowncharacteristics of negative long spark discharges,which have been widely used to design the lightning shielding system of transmission lines and structures.In recent years,the scale of the power facilities is increased dramatically with the rising of power grid's voltage level.The impact of upward connecting leader launched from those large-scale facilities on the lightning shielding performance cannot be neglected;otherwise,the validity of the EGM in the lightning shielding design of EHV and UHV transmission lines will be challenged.The research evolutions on the lightning striking distance,the lightning simulation experiments and the positive upward connecting leader process by using laboratory long sparks are reviewed and discussed in this paper.展开更多
To improve the efficiency of coal seam water injection,the influence of nanofluids on coal surface wettability was studied based on the nano drag reduction and injection enhancement technology in the field of tertiary...To improve the efficiency of coal seam water injection,the influence of nanofluids on coal surface wettability was studied based on the nano drag reduction and injection enhancement technology in the field of tertiary oil recovery.The composition optimization and performance evaluation of nanofluids with nano-silica and sodium lauryl sulfate as the main components were carried out,and the effects of the nanofluid with the optimal ratio on coal wettability were studied through spontaneous upward imbibition experiments.The results show that the composite nanofluid has a lower surface tension,and the lowest value of the interfacial tension is 15.79 m N/m.Therefore,the composite nanofluid can enhance the wettability of coal.However,its effects on coal samples with different metamorphic degrees is different,that is,low rank coal is the largest,middle rank coal is the second,and high rank coal is the least.In addition,a functional relationship between time and imbibition height is found for pulverized coal with different particle sizes.When the particle size of pulverized coal is 60–80 mesh,the wettability of nanofluid to coal is best.The findings in this paper provide a new perspective for improving the water injection efficiency for coal seams with low permeability.展开更多
Although paid to upward shift response to global phenomenon at low zones did not receive increasing attention has been of plant species in altitude as a warming, research on this altitudinal and low latitudinal enoug...Although paid to upward shift response to global phenomenon at low zones did not receive increasing attention has been of plant species in altitude as a warming, research on this altitudinal and low latitudinal enough attention. In this study, an investigation was carried out to test the relationship between the upward spread of Moso bamboo （Phyllostachys pubescens） along altitudinal gradient and the increasing air temperature over the past decade within the Tianmu Mountain region, situated in southeastern China. Results showed that the peak elevation of Moso bamboo population establishment rose by an average of 9.8 m （±2.7 m） during the past decade and significant correlation existed with mean annual temperature （P 〈 0.0001, n = 339） but not with annual precipitation （P = 0.7, n = 339）, indicating that the upward shift of Moso bamboo along altitudinal gradients was driven primarily by warming temperatures. This upward shift could potentially reduce biodiversity by altering the species composition of the ecosystem. However, there is also the potential for increased carbon sequestration capacity of local forest systems, which would produce an additional carbon sink to combat rising atmospheric C02 concentrations and future global warming.展开更多
Microstructure evolution and properties of a Cu-Cr-Ag alloy during the continuous manufacturing process were investigated in detail by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)in the s...Microstructure evolution and properties of a Cu-Cr-Ag alloy during the continuous manufacturing process were investigated in detail by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)in the study.The Cu-Cr-Ag alloy rod with uniform compositions is fabricated by upward continuous casting technology.Few of the Cr phases are observed in the ascast alloy.During the continuous extrusion process,the severe shear deformation and the dynamic aging occur.The average grain size of as-extruded alloy is much smaller than that of as-cast alloy.Both fcc and bcc Cr precipitates appear in the matrix.The interaction mode between dislocations and precipitates can be identified as Orowan bypass mode according to the TEM observations.The overall difference in the yield strength between as-cast and as-extruded Cu-Cr-Ag alloy is attributed to solid solution strengthening,grain refinement strengthening,precipitation hardening and working hardening.展开更多
Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed ...Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed in this paper.By this method,the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed,the extent of roof-side deformation thereby is lessened,and boundary angle of roof-side subsidence is reduced by 5°-10°.The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials.A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining method.The application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.展开更多
TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3A...TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.展开更多
Fluid flow pattern and buoyancy force support the motion of nonmetallic inclusions toward thetundish slag. Upward molten flow was investigated. To understand the fundamentals of the process, physical modelling was car...Fluid flow pattern and buoyancy force support the motion of nonmetallic inclusions toward thetundish slag. Upward molten flow was investigated. To understand the fundamentals of the process, physical modelling was carried out with the utilization of a 1 ： 4 scale model. Numerical modelling was carried out in line with the physicai modelling to examine details of the flow pattern and rotational effect caused by the upward flow with the Commercial CFD （Computational Fluid Dynamics） package environment, FLUENT. The two-equation κ-ε model was used to simulate the turbulence. Multiphase fluid flow was numerically simulated by using the Volume of Fluid （VoF） method. The simulation can predict free surface waves and other phenomena, which can be used to optimize these important metallurgical operations.展开更多
A new approach to the massive production of TiC whiskers with high purity and low cost was presented. It is a modified carbothermal reduction method （MCTR） characterized by argon stream flowing vertically and passin...A new approach to the massive production of TiC whiskers with high purity and low cost was presented. It is a modified carbothermal reduction method （MCTR） characterized by argon stream flowing vertically and passing through the interior of the mixture of raw materials. It is found for the first time that there is an optimum flow of the upward flowing argon stream, at which large quantity of high quality TiC can be obtained. This paper described the new method, analyzed the mechanism and conditions for the formation of high purity TiC whiskers on a large scale, and compared MCTR with the traditional carbothermal reduction method （TCTR）. Based on the analysis and comparison, it is concluded that in order to produce high quality transition metal carbides, nitrides and carbonitrides with low cost TCTR must be replaced by MCTR.展开更多
A 3-D chemical transport model (OSLO CTM2) is used to investigate the influences of the increasing anthropogenic emission in India. The model is capable of reproducing the observational results of the INDOEX experimen...A 3-D chemical transport model (OSLO CTM2) is used to investigate the influences of the increasing anthropogenic emission in India. The model is capable of reproducing the observational results of the INDOEX experiment and the measurements in summer over India well. The model results show that when NOx and CO emissions in India are doubled, ozone concentration increases, and global average OH decreases a little. Under the effects of the Indian summer monsoon, NOx and CO in India are efficiently transported into the middle and upper troposphere by the upward current and the convective activities so that the NOX, CO, and ozone in the middle and upper troposphere significantly increase with the increasing NOx and CO emissions. These increases extensively influence a part of Asia, Africa, and Europe, and persist from June to September.展开更多
The distribution of precipitation field from the typhoon Haitang(2005) during its landing on Fujian province shows obvious asymmetric feature.Based on the NCEP/NCAR FNL(Final Analysis) data,this study reveals the cont...The distribution of precipitation field from the typhoon Haitang(2005) during its landing on Fujian province shows obvious asymmetric feature.Based on the NCEP/NCAR FNL(Final Analysis) data,this study reveals the contributions of atmospheric factor to the asymmetrical distribution characteristics of precipitation associated with the typhoon,through the analysis of water vapor condition,vertical ascending motion condition,the calculation of the dry Q vector and its decomposition,and adiabatic heating in the air column of 1000hPa-600hPa(lower atmosphere) and500hPa-100hPa(upper atmosphere).The results are as follows:(1) In the lower atmosphere,the humidity on both sides of typhoon path can be equivalent,while it is more wet on the right side than left in the upper atmosphere,which obviously presents asymmetric distribution characteristics.(2) Both range and intensity of the vertical motion on the right side are wider and stronger than counterparts on the left side no matter in the lower or upper atmosphere.(3) In the upper atmosphere,forcing role of atmosphere in vertical upward motion on the right side of typhoon path is the same as that on the left,while it is significantly different in the lower atmosphere,which is significantly broader in scope and stronger in the intensity,along with obvious asymmetric distribution characteristics.In addition,the further analysis of the Q vector decomposition indicates that the forcing effect of mesoscale weather systems on vertical upward motion is stronger than that of large scale weather systems in the lower atmosphere.(4) The adiabatic heating always exists on both lower and upper atmosphere,and the range and intensity of the adiabatic heating forcing showed asymmetric distribution on both lower and upper atmosphere.(5) In a summary,the upper atmosphere humidity conditions,the forcing role of lower atmosphere in vertical upward motion,especially,to mesoscale weather system,and adiabatic heating in the lower atmosphere,all show similar asymmetric distribution characteristics to that of precipitation field from the typhoon Haitang(2005),that is to say,the atmospheric factors as mentioned above are all contributed to genesis of the asymmetric distribution characteristics of precipitation.展开更多
The effect of electromagnetic vibration(EMV)on the solidification structure of Cu-15Ni-8Sn alloy during bulk solidification and the upward continuous casting was investigated experimentally and numerically.The bulk so...The effect of electromagnetic vibration(EMV)on the solidification structure of Cu-15Ni-8Sn alloy during bulk solidification and the upward continuous casting was investigated experimentally and numerically.The bulk solidification results indicated that in the case of B=0.5 T and J=1.27×10^(5)A/m^(2),the most effective grain refinement frequency was at f=10 Hz,where fine non-dendrites were obtained.The solidification structure became coarser at f=0.1 Hz and f=1 Hz compared to the case of f=10 Hz,while no grain refinement was observed at f=100 Hz.The numerical simulations showed that at f=10 Hz,the strong melt convection surrounding the primary solid phase promotes the diffusion of the rejected solute,consequently,resulting in a reduction of the solute boundary layer,which leads to the decrease in the nucleation-free zone(NFZ)and the grain refinement.Additionally,the most effective grain refinement frequency transformed to 1 Hz when the electromagnetic force was reduced by five times.Moreover,we proposed that the most effective grain refinement frequency range aligns with the EMV-induced relative displacement in the range of 10^(2)–10^(3)μm.Finally,the upward continuous casting was conducted to validate the relative displacement range,and the experimental results matched well.展开更多
A theoretical discussion of the discharge effects of upward lightning simulated with a fine-resolution 2D thunderstorm model is performed in this paper,and the results reveal that the estimates of the total induced ch...A theoretical discussion of the discharge effects of upward lightning simulated with a fine-resolution 2D thunderstorm model is performed in this paper,and the results reveal that the estimates of the total induced charge on the upward lightning discharge channels range from 0.67 to 118.8 C,and the average value is 19.0 C,while the ratio of the induced charge on the leader channels to the total opposite-polarity charge in the discharge region ranges from 5.9%to 47.3%,with an average value of 14.7%.Moreover,the average value of the space electrostatic energy consumed by upward lightning is 1.06×10^9 J.The above values are lower than those related to intracloud lightning discharges.The density of the deposited opposite-polarity charge is comparable in magnitude to that of the preexisting charge in the discharge area,and the deposition of these opposite-polarity charges rapidly destroys the original space potential well in the discharge area and greatly reduces the space electric field strength.In addition,these opposite-polarity charges are redistributed with the development of thunderstorms.The space charge redistribution caused by lightning discharges partly accounts for the complexity of the charge structures in a thunderstorm,and the complexity gradually decreases with the charge neutralization process.展开更多
Objective Several well-exposed gravity flow deposits in the Early Cretaceous Lingshandao Formation provide a rare opportunity to study deep-water processes. The main objective of this work is to establish the spatial...Objective Several well-exposed gravity flow deposits in the Early Cretaceous Lingshandao Formation provide a rare opportunity to study deep-water processes. The main objective of this work is to establish the spatial and temporal relationships between the various gravity flow deposits, and thus to establish their sequence stratigraphic patterns and depositional conditions.展开更多
During construction,the shield linings of tunnels often face the problem of local or overall upward movement after leaving the shield tail in soft soil areas or during some large diameter shield projects.Differential ...During construction,the shield linings of tunnels often face the problem of local or overall upward movement after leaving the shield tail in soft soil areas or during some large diameter shield projects.Differential floating will increase the initial stress on the segments and bolts which is harmful to the service performance of the tunnel.In this study we used a random forest(RF)algorithm combined particle swarm optimization(PSO)and 5-fold cross-validation(5-fold CV)to predict the maximum upward displacement of tunnel linings induced by shield tunnel excavation.The mechanism and factors causing upward movement of the tunnel lining are comprehensively summarized.Twelve input variables were selected according to results from analysis of influencing factors.The prediction performance of two models,PSO-RF and RF(default)were compared.The Gini value was obtained to represent the relative importance of the influencing factors to the upward displacement of linings.The PSO-RF model successfully predicted the maximum upward displacement of the tunnel linings with a low error(mean absolute error(MAE)=4.04 mm,root mean square error(RMSE)=5.67 mm)and high correlation(R^(2)=0.915).The thrust and depth of the tunnel were the most important factors in the prediction model influencing the upward displacement of the tunnel linings.展开更多
基金supported by the China Postdoctoral Science Foundation(Certificate Number:2024M760126).
文摘This study examined the relationship between inclusive leadership and subordinates’upward voice,focusing on the mediating role of psychological safety and the moderating role of collectivism.Data were collected from 284 subordinates and supervisors across 11 organizations in China in three cross-lagged waves.Structural equation modeling results indicated that inclusive leadership was associated with subordinates’upward voice via psychological safety.Moreover,collectivism strengthens the association between inclusive leadership and upward voice via psychological safety,leading to a higher upward voice.These findings highlight the importance of inclusive leadership in fostering an environment that promotes open communication and psychological safety between supervisors and subordinates,ultimately enhancing workplace health and well-being.The implications of these findings suggest that management practices should cultivate inclusive leadership behaviors for enhancing psychological safety,and encouraging subordinates to voice their opinions for the overall success of the organization.
文摘Background:Platform algorithms driving content presentation are profoundly shaping the experience of younger users.While prior research has examined anxiety stemming from young adults’social media usage,the link between upward social comparison and anxiety remains unclear.This study aims to investigate the mediating role of upward social comparison in this relationship and determine the moderating role of psychological resilience.Methods:A cross-sectional survey was conducted among 562 young Chinese adults aged 18–35(53%female).Data were collected via an online questionnaire employing validated measurement instruments,including scales for social media usage patterns,upward comparator behaviour(INCOM),anxiety levels(GAD-7),and psychological resilience(RSA).Correlation analysis,mediation analysis,and moderation analysis were conducted using SPSS 29.0.Results:As predicted,the results indicate that upward social comparison mediates the relationship between both active(β=−0.11,95%CI=[−0.15,−0.08])and passive(β=0.11,95%CI=[0.07,0.15])social media use and anxiety.Furthermore,psychological resilience(β_(low)=0.10,95%CI=[0.06,0.14];β_(high)=0.05,95%CI=[0.01,0.09])moderated the indirect effect of passive social media use on anxiety through upward social comparison.Conclusion:The findings indicate that upward social comparison significantly influences the anxiety experienced by young social media users,with psychological resilience playing a crucial moderating role.These results offer valuable insights for optimizing content recommendation algorithms on social media platforms to better support young adults’mental health.
基金Project(10872218) supported by the National Natural Science Foundation of ChinaProject(2010CB732004) supported by the National Key Basic Research Program of China+1 种基金Project(20090461022) supported by the National Postdoctoral Foundation of ChinaProject (11MX21) supported by the Students' Innovation Project Aubsidize Award of Arcelor Mittal
文摘Xinli district of Sanshandao Gold Mine is the first subsea metal mine in China.To achieve 6 kt/d production capacity under the premise of safe mining,high-intensity mining might destroy the in-situ stress filed and the stability of rockmass.According to sampling and testing of ore-rock and backfill and in-situ stress field measurement,safety factor method calculation model based on stress-strain strength reduction at arbitrary points and Mohr-Coulomb yield criterion was established and limit displacement subsidence values under the safety factor of different limit stoping steps were calculated.The results from three years in-situ mining and strata movement monitoring using multi-point displacements meter showed that the lower settlement frame stope hierarchical level filling mining method,mining sequence are reasonable and rockmass stability evaluation using safety factor method,in-situ real-time monitoring can provide the technical foundation for the safety of seabed mining.
文摘There has been a long tradition in the history of Hungarian intellectuals that dates as far back as the 1930s.It became well-known as the clash between the“populist”(nepies)and“urbanite”(urbanus)camps as two factions of the intellectual classes or status groups.However,the author’s historical investigations show that this clash originated during the first reform period of Hungarian history(1830-1848),when the“Centralists”under the leadership of József Eötvös confronted the“Municipalists”whose leading figure was Lajos Kossuth.The former group represented the Western Europe oriented faction,who heavily called into question the county system,while the members of the latter group warranted it as the bulwark of the Hungarian constitution.The conflict was renewed between the two world wars as“westernizing”urbanites opposed the“Magyar”-oriented populists.Also,after the regime change in the 1990s,this old clash posited itself politically first as the strife between the Hungarian Democratic Forum and the Free Democrats and later on it got the form of a European-oriented Leftist-Liberal wing facing the moderate Right.The desperate struggle between the two political wings appeared at the local level as well.The author describes a paradigmatic case of the overall contradiction in a case study.During the local elections in a Hungarian village the post-communist mayor was forced to run against a traditionally religious mayor,while the entire village population,including civil society,followed the desperate clash up to an unserviceable stage.At this point,a third mayor candidate stepped in competing with both former enemies and won the exceptional election.The new mayor transcended both the post-communist era and the oppositional mayor of traditional religious background,for as the great-grand child of a landowner in the period preceding the Second World War who was persecuted in the Communist era;this mayor restituted the continuity with the ancient landowner class.And at the same time,while jettisoning the old-fashioned religion,she exhibited a certain attachment to a new type,as it were,a postmodern religiosity.
文摘It is one of the most effective ways to use laboratory long air gap discharges for investigating the fundamental process involved in the lightning strike.During the 1960s and the 1970s,the electro-geometrical method(EGM)and the rolling sphere method were developed base on the breakdowncharacteristics of negative long spark discharges,which have been widely used to design the lightning shielding system of transmission lines and structures.In recent years,the scale of the power facilities is increased dramatically with the rising of power grid's voltage level.The impact of upward connecting leader launched from those large-scale facilities on the lightning shielding performance cannot be neglected;otherwise,the validity of the EGM in the lightning shielding design of EHV and UHV transmission lines will be challenged.The research evolutions on the lightning striking distance,the lightning simulation experiments and the positive upward connecting leader process by using laboratory long sparks are reviewed and discussed in this paper.
基金supported by the National Natural Science Foundation of China(Nos.51974176,51934004,52174194)the Shandong Province Natural Science Foundation of Outstanding Youth Fund(ZR2020JQ22)+1 种基金the Shandong Province Colleges and Universities Youth Innovation and Technology Support Program(2019KJH006)the Special funds for Taishan scholar project(TS20190935)。
文摘To improve the efficiency of coal seam water injection,the influence of nanofluids on coal surface wettability was studied based on the nano drag reduction and injection enhancement technology in the field of tertiary oil recovery.The composition optimization and performance evaluation of nanofluids with nano-silica and sodium lauryl sulfate as the main components were carried out,and the effects of the nanofluid with the optimal ratio on coal wettability were studied through spontaneous upward imbibition experiments.The results show that the composite nanofluid has a lower surface tension,and the lowest value of the interfacial tension is 15.79 m N/m.Therefore,the composite nanofluid can enhance the wettability of coal.However,its effects on coal samples with different metamorphic degrees is different,that is,low rank coal is the largest,middle rank coal is the second,and high rank coal is the least.In addition,a functional relationship between time and imbibition height is found for pulverized coal with different particle sizes.When the particle size of pulverized coal is 60–80 mesh,the wettability of nanofluid to coal is best.The findings in this paper provide a new perspective for improving the water injection efficiency for coal seams with low permeability.
基金funded by the National Nature Science Foundation of China (Grant No. 31070440,31270517)China QianRen Program,NSERC-Discovery GrantZhejiang A & F University Research and Development Fund (2012FR023)
文摘Although paid to upward shift response to global phenomenon at low zones did not receive increasing attention has been of plant species in altitude as a warming, research on this altitudinal and low latitudinal enough attention. In this study, an investigation was carried out to test the relationship between the upward spread of Moso bamboo （Phyllostachys pubescens） along altitudinal gradient and the increasing air temperature over the past decade within the Tianmu Mountain region, situated in southeastern China. Results showed that the peak elevation of Moso bamboo population establishment rose by an average of 9.8 m （±2.7 m） during the past decade and significant correlation existed with mean annual temperature （P 〈 0.0001, n = 339） but not with annual precipitation （P = 0.7, n = 339）, indicating that the upward shift of Moso bamboo along altitudinal gradients was driven primarily by warming temperatures. This upward shift could potentially reduce biodiversity by altering the species composition of the ecosystem. However, there is also the potential for increased carbon sequestration capacity of local forest systems, which would produce an additional carbon sink to combat rising atmospheric C02 concentrations and future global warming.
基金financially supported by the National Key R&D Program of China(No.2016YFB0301400)the National Natural Science Foundation of China(No.51601017)。
文摘Microstructure evolution and properties of a Cu-Cr-Ag alloy during the continuous manufacturing process were investigated in detail by scanning electron microscopy(SEM)and transmission electron microscopy(TEM)in the study.The Cu-Cr-Ag alloy rod with uniform compositions is fabricated by upward continuous casting technology.Few of the Cr phases are observed in the ascast alloy.During the continuous extrusion process,the severe shear deformation and the dynamic aging occur.The average grain size of as-extruded alloy is much smaller than that of as-cast alloy.Both fcc and bcc Cr precipitates appear in the matrix.The interaction mode between dislocations and precipitates can be identified as Orowan bypass mode according to the TEM observations.The overall difference in the yield strength between as-cast and as-extruded Cu-Cr-Ag alloy is attributed to solid solution strengthening,grain refinement strengthening,precipitation hardening and working hardening.
基金sponsored by the National Natural Science Foundation of China(Nos.51574242 and 5097412).
文摘Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed in this paper.By this method,the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed,the extent of roof-side deformation thereby is lessened,and boundary angle of roof-side subsidence is reduced by 5°-10°.The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials.A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining method.The application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.
文摘TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.
文摘Fluid flow pattern and buoyancy force support the motion of nonmetallic inclusions toward thetundish slag. Upward molten flow was investigated. To understand the fundamentals of the process, physical modelling was carried out with the utilization of a 1 ： 4 scale model. Numerical modelling was carried out in line with the physicai modelling to examine details of the flow pattern and rotational effect caused by the upward flow with the Commercial CFD （Computational Fluid Dynamics） package environment, FLUENT. The two-equation κ-ε model was used to simulate the turbulence. Multiphase fluid flow was numerically simulated by using the Volume of Fluid （VoF） method. The simulation can predict free surface waves and other phenomena, which can be used to optimize these important metallurgical operations.
文摘A new approach to the massive production of TiC whiskers with high purity and low cost was presented. It is a modified carbothermal reduction method （MCTR） characterized by argon stream flowing vertically and passing through the interior of the mixture of raw materials. It is found for the first time that there is an optimum flow of the upward flowing argon stream, at which large quantity of high quality TiC can be obtained. This paper described the new method, analyzed the mechanism and conditions for the formation of high purity TiC whiskers on a large scale, and compared MCTR with the traditional carbothermal reduction method （TCTR）. Based on the analysis and comparison, it is concluded that in order to produce high quality transition metal carbides, nitrides and carbonitrides with low cost TCTR must be replaced by MCTR.
基金supported by the Young Grant of the Chinese Academy of Meteorological Sciencesthe Norwegian Research Council and the Natural Science Foundation of China.
文摘A 3-D chemical transport model (OSLO CTM2) is used to investigate the influences of the increasing anthropogenic emission in India. The model is capable of reproducing the observational results of the INDOEX experiment and the measurements in summer over India well. The model results show that when NOx and CO emissions in India are doubled, ozone concentration increases, and global average OH decreases a little. Under the effects of the Indian summer monsoon, NOx and CO in India are efficiently transported into the middle and upper troposphere by the upward current and the convective activities so that the NOX, CO, and ozone in the middle and upper troposphere significantly increase with the increasing NOx and CO emissions. These increases extensively influence a part of Asia, Africa, and Europe, and persist from June to September.
基金National Natural Science Foundation of China(40875025,41175050,41275021,41475039,41475041,41575048)Public Sector(Meteorology)Research of China(GYHY201306012,GYHY201506007)
文摘The distribution of precipitation field from the typhoon Haitang(2005) during its landing on Fujian province shows obvious asymmetric feature.Based on the NCEP/NCAR FNL(Final Analysis) data,this study reveals the contributions of atmospheric factor to the asymmetrical distribution characteristics of precipitation associated with the typhoon,through the analysis of water vapor condition,vertical ascending motion condition,the calculation of the dry Q vector and its decomposition,and adiabatic heating in the air column of 1000hPa-600hPa(lower atmosphere) and500hPa-100hPa(upper atmosphere).The results are as follows:(1) In the lower atmosphere,the humidity on both sides of typhoon path can be equivalent,while it is more wet on the right side than left in the upper atmosphere,which obviously presents asymmetric distribution characteristics.(2) Both range and intensity of the vertical motion on the right side are wider and stronger than counterparts on the left side no matter in the lower or upper atmosphere.(3) In the upper atmosphere,forcing role of atmosphere in vertical upward motion on the right side of typhoon path is the same as that on the left,while it is significantly different in the lower atmosphere,which is significantly broader in scope and stronger in the intensity,along with obvious asymmetric distribution characteristics.In addition,the further analysis of the Q vector decomposition indicates that the forcing effect of mesoscale weather systems on vertical upward motion is stronger than that of large scale weather systems in the lower atmosphere.(4) The adiabatic heating always exists on both lower and upper atmosphere,and the range and intensity of the adiabatic heating forcing showed asymmetric distribution on both lower and upper atmosphere.(5) In a summary,the upper atmosphere humidity conditions,the forcing role of lower atmosphere in vertical upward motion,especially,to mesoscale weather system,and adiabatic heating in the lower atmosphere,all show similar asymmetric distribution characteristics to that of precipitation field from the typhoon Haitang(2005),that is to say,the atmospheric factors as mentioned above are all contributed to genesis of the asymmetric distribution characteristics of precipitation.
基金Project supported by China Postdoctoral Science Foundation （ 10000072311030 ）, Scienee technology Research Foundation of Shandong University of China {10000080398125）.
基金financially supported by the National Natural Science Foundation of China(Nos.51904184,52204392,52274385,and 52204347)the National Key Research and Development Program of China(No.2022YFC2904900)the Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001).
文摘The effect of electromagnetic vibration(EMV)on the solidification structure of Cu-15Ni-8Sn alloy during bulk solidification and the upward continuous casting was investigated experimentally and numerically.The bulk solidification results indicated that in the case of B=0.5 T and J=1.27×10^(5)A/m^(2),the most effective grain refinement frequency was at f=10 Hz,where fine non-dendrites were obtained.The solidification structure became coarser at f=0.1 Hz and f=1 Hz compared to the case of f=10 Hz,while no grain refinement was observed at f=100 Hz.The numerical simulations showed that at f=10 Hz,the strong melt convection surrounding the primary solid phase promotes the diffusion of the rejected solute,consequently,resulting in a reduction of the solute boundary layer,which leads to the decrease in the nucleation-free zone(NFZ)and the grain refinement.Additionally,the most effective grain refinement frequency transformed to 1 Hz when the electromagnetic force was reduced by five times.Moreover,we proposed that the most effective grain refinement frequency range aligns with the EMV-induced relative displacement in the range of 10^(2)–10^(3)μm.Finally,the upward continuous casting was conducted to validate the relative displacement range,and the experimental results matched well.
基金This research was supported by the National Key Research and Development Program of China(Grant No.2017YFC1501504)the National Natural Science Foundation of China(Grant Nos.41875003,41805002)the Open Research Program of the State Key Laboratory of Severe Weather(Grant No.2019LASW-A03).
文摘A theoretical discussion of the discharge effects of upward lightning simulated with a fine-resolution 2D thunderstorm model is performed in this paper,and the results reveal that the estimates of the total induced charge on the upward lightning discharge channels range from 0.67 to 118.8 C,and the average value is 19.0 C,while the ratio of the induced charge on the leader channels to the total opposite-polarity charge in the discharge region ranges from 5.9%to 47.3%,with an average value of 14.7%.Moreover,the average value of the space electrostatic energy consumed by upward lightning is 1.06×10^9 J.The above values are lower than those related to intracloud lightning discharges.The density of the deposited opposite-polarity charge is comparable in magnitude to that of the preexisting charge in the discharge area,and the deposition of these opposite-polarity charges rapidly destroys the original space potential well in the discharge area and greatly reduces the space electric field strength.In addition,these opposite-polarity charges are redistributed with the development of thunderstorms.The space charge redistribution caused by lightning discharges partly accounts for the complexity of the charge structures in a thunderstorm,and the complexity gradually decreases with the charge neutralization process.
基金supported by the National Natural Science Foundation of China(grant No.41372135)Shandong University of Science and Technology Research Fund(grant No.2015TDJH101)
文摘Objective Several well-exposed gravity flow deposits in the Early Cretaceous Lingshandao Formation provide a rare opportunity to study deep-water processes. The main objective of this work is to establish the spatial and temporal relationships between the various gravity flow deposits, and thus to establish their sequence stratigraphic patterns and depositional conditions.
基金supported by the Basic Science Center Program for Multiphase Evolution in Hyper Gravity of the National Natural Science Foundation of China(No.51988101)the National Natural Science Foundation of China(No.52178306)the Zhejiang Provincial Natural Science Foundation of China(No.LR19E080002).
文摘During construction,the shield linings of tunnels often face the problem of local or overall upward movement after leaving the shield tail in soft soil areas or during some large diameter shield projects.Differential floating will increase the initial stress on the segments and bolts which is harmful to the service performance of the tunnel.In this study we used a random forest(RF)algorithm combined particle swarm optimization(PSO)and 5-fold cross-validation(5-fold CV)to predict the maximum upward displacement of tunnel linings induced by shield tunnel excavation.The mechanism and factors causing upward movement of the tunnel lining are comprehensively summarized.Twelve input variables were selected according to results from analysis of influencing factors.The prediction performance of two models,PSO-RF and RF(default)were compared.The Gini value was obtained to represent the relative importance of the influencing factors to the upward displacement of linings.The PSO-RF model successfully predicted the maximum upward displacement of the tunnel linings with a low error(mean absolute error(MAE)=4.04 mm,root mean square error(RMSE)=5.67 mm)and high correlation(R^(2)=0.915).The thrust and depth of the tunnel were the most important factors in the prediction model influencing the upward displacement of the tunnel linings.
