Deeply buried mountain tunnels are often exposed to the risk of rock bursts,which always cause serious damage to the supporting structures and threaten the safety of the engineers.Due to the limited data available,a s...Deeply buried mountain tunnels are often exposed to the risk of rock bursts,which always cause serious damage to the supporting structures and threaten the safety of the engineers.Due to the limited data available,a suitable approach to predict the rockburst tendency at the preliminary stage becomes very important.In this study,an integrated methodology combining 3D initial stress inversion and rockburst tendency prediction was developed and subsequently applied to a case study of the Sangzhuling Tunnel on the Sichuan–Tibet Railway.The numerical modelling involved inverting the initial stress field using a multiple linear regression method.The tunnel excavation was simulated separately by FDM and DEM,based on a stress boundary condition from the inverted stress field.The comparative analysis demonstrates that the rockburst ratio calculated using DEM(76.70%)exhibits a slight increase compared to FDM(75.38%),and the rockburst location is consistent with the actual situation.This suggests that DEM is more suitable for simulating the stress redistribution during excavation in a jointed rock mass.The numerical simulation combined with the deviatoric stress approach effectively predicts rockburst tendency,meeting the engineering requirements.Despite its limitations,numerical simulation remains a reliable method for predicting rock bursts.展开更多
To investigate the mechanical response during failure and the impact tendency characteristics of gangue-coal combined structure,uniaxial compression tests were conducted on nine groups of combined structures,each with...To investigate the mechanical response during failure and the impact tendency characteristics of gangue-coal combined structure,uniaxial compression tests were conducted on nine groups of combined structures,each with varying gangue thicknesses and positions.The response patterns of compressive strength,elastic modulus,pre-peak accumulated energy,elastic energy index,and impact energy index were systematically analyzed.Furthermore,a new index for evaluating the impact tendency of gangue-containing coal was proposed,and its effectiveness was verified.The findings are as follows:(1)As the gangue thickness increases,both the compressive strength and the pre-peak energy of the combined structure decrease,whereas the elastic modulus increases accordingly.When the gangue is located in the lower middle position,the combined structure exhibits the lowest compressive strength and elastic modulus but the highest pre peak energy.(2)As the gangue shifts toward the middle position of the combined structure,the failure mode gradually transitions from comple te“crushing”failure to an incomplete“point-type”failure.As gangue thickness further increases,the failure region evolves from overall failure to localized failure,with the degree of failure shifting from complete to incomplete.The K_(crc)value corresponding to“crushing”complete failure is higher and has a stronger impact tendency compared to“point-type”incomplete failure.(3)The proposed comprehensive impact instability evaluation index K_(crc)for the gangue-coal combined structure has shown a significant positive correlation with compressive strength(R_(c))and impact energy index(K_(E)),further verifyi ng its rationality in comprehensively assessing the impact tendency of gangue-containing coal bodies.Applying this index to the evaluation of gangue-containing coal seams provides a more accurate reflection of their impact tendency compared with the residual energy index,which has a wide range of potential applications and practical significance.展开更多
The synoptic process of a super Arctic cyclone in August 2016(AC16)is investigated based on the Weather Research and Forecasting(WRF)model,and the key factors affecting the rapid intensification(RI)of AC16 and their r...The synoptic process of a super Arctic cyclone in August 2016(AC16)is investigated based on the Weather Research and Forecasting(WRF)model,and the key factors affecting the rapid intensification(RI)of AC16 and their relative contributions are analyzed by diagnosing a new surface pressure tendency equation(SPTE).The major physical mechanisms behind the two RI stages of AC16 are revealed.The trajectory,intensity changes,and structural characteristics of AC16 are well simulated by the WRF model.A diagnosis based on the SPTE promisingly reproduces the two RI stages of AC16.The leading factor that influenced the intensity of AC16 was identified to be the air-column potential temperature tendency,while the pressure change at the upper boundary had less of an impact.Further analysis reveals that the horizontal potential temperature advection was the decisive factor in a warming of the air column.Specifically,the upper-level warm advection generated by the strong wind field of the upper-level jet played a dominant role in warming the air column,which caused the initial RI of AC16.The AC16 movement into a strong potential temperature gradient generated by tropopause polar vortices increased the upper-level warm advection,which warmed the air column and thereby induced the second RI of AC16.However,the net effect of vertical potential temperature advection and latent heating,as well as radiation processes,caused a cooling of the air column and thereby negatively contributed to the RI of AC16.展开更多
To evaluate the accuracy of rockburst tendency classification in coal-bearing sandstone strata,this study conducted uniaxial compression loading and unloading tests on sandstone samples with four distinct grain sizes....To evaluate the accuracy of rockburst tendency classification in coal-bearing sandstone strata,this study conducted uniaxial compression loading and unloading tests on sandstone samples with four distinct grain sizes.The tests involved loading the samples to 60%,70%,and 80%of their uniaxial compressive strength,followed by unloading and reloading until failure.Key parameters such as the elastic energy index and linear elasticity criteria were derived from these tests.Additionally,rock fragments were collected to calculate their initial ejection kinetic energy,serving as a measure of rockburst tendency.The classification of rockburst tendency was conducted using grading methods based on burst energy index(WET),pre-peak stored elastic energy(PES)and experimental observations.Multi-class classification and regression analyses were applied to machine learning models using experimental data to predict rockburst tendency levels.A comparative analysis of models from two libraries revealed that the Random Forest model achieved the highest accuracy in classification,while the Ada Boost Regressor model excelled in regression predictions.This study highlights that on a laboratory scale,integrating ejection kinetic energy with the unloading ratio,failure load,W_(ET)and PES through machine learning offers a highly accurate and reliable approach for determining rockburst tendency levels.展开更多
In order to study the mechanics,acoustic emission(AE)and electromagnetic emission(EME)response law of bursting liability coal at different loading rates,uniaxial compression tests were carried out on coal mass from Ko...In order to study the mechanics,acoustic emission(AE)and electromagnetic emission(EME)response law of bursting liability coal at different loading rates,uniaxial compression tests were carried out on coal mass from Konggu Coal Mine.The corresponding relations among mechanical properties,AE and EME signals in the process of coal failure under loading were analyzed,and the energy evolution law of coal failure with bursting liability under loading rate was discussed.The results show that within a certain range of loading rate,the higher the loading rate,the higher the compressive strength and peak load of bursting liability coal,and the shorter the time for coal to reach the peak load.Under different loading rates,the mechanics,AE and EME signals of coal samples can be well corresponded.When the loading rate is low,the number of blocks destroyed of coal sample is large and the block size is relatively small,and the blocks are mainly scattered around the test platform.When the loading rate is high,the number of damaged blocks is relatively small and the block size is relatively large,and the blocks are far away from the test bench.When loading at a low rate,the internal cracks in coal can be fully developed and connected,and the energy release rate is relatively uniform in the process of loading and failure of coal sample.In the case of high loading rate,the energy release rate of coal sample in the loading process is much smaller than that in the moment of failure.Combining the above test results with the actual situation of the working face,it can be concluded that the total energy stored in the coal of fast mining increases and the threshold of impact decreases compared with that of slow mining.Therefore,under the disturbance of external dynamic load,rapid mining is more likely to induce rock burst.展开更多
Sustainable clean energy is gradually replacing traditional fossil energy sources in important industrial applications and is placing higher demands on the technologies of energy storage and transportation.The develop...Sustainable clean energy is gradually replacing traditional fossil energy sources in important industrial applications and is placing higher demands on the technologies of energy storage and transportation.The development of multi-principal element alloys(MPEAs)offers a new idea for safe solid-state hydrogen storage materials.Owing to the unique characteristics of complex components and severe lattice distortion,MPEAs are predicted to have better hydrogen storage performance and more probability for modulation and enhancement,allowing them to meet the requirements of different hydrogen storage applications.The unique structure characteristic potentially devotes the improvement of thermodynamic and kinetic performance,such as the hydrogen storage capacity and hydrogen adsorption/desorption properties.Recently,several important modulation factors originating from components and structures facilitate the understanding of the correlation between hydrogen storage properties and microstructure.Here,we highlight the correlations of hydrogen storage mechanism,with the degree of lattice distortion,the element variation or segregation and valence electron concentration.Moreover,the development tendency on the hydrogen storage mechanism based on the advanced microscopy and computational approach is proposed.Especially,the chemically short-range ordered structure in MPEAs is predicted as a potential modification factor of the hydrogen/tritium storage properties.展开更多
Objectives:This study investigates the association between victimization experience and the tendency to defend on behalf of victims during school bullying incidents in public settings,with a focus on the mediating eff...Objectives:This study investigates the association between victimization experience and the tendency to defend on behalf of victims during school bullying incidents in public settings,with a focus on the mediating effect of empathy and the moderating role of school level among Chinese children and adolescents.Methods:Data were collected by a cross-sectional survey.A total of 1491 students in Grades 4–11 participated(Boys=52.8%;Mean_(age)=13.00 years,Standard Deviation_(age)=2.31).Structural equation modeling is employed to test the hypotheses.Results:The results indicate that empathy measures partially mediate the relationship between victimization experience and defending tendency in public in-school bullying situations.In particular,individuals with a history of victimization typically demonstrate lower levels of empathy.They are less likely to protect victims in school bullying situations in the presence of others,which suggests that empathy plays a significant mediating role in this relationship.Group differences were found between primary and secondary school students,which indicates that the hypothesized model should be considered through a developmental perspective.Conclusions:The findings of this study emphasize the importance of children’s benign peer relationships,and practitioners are encouraged to prevent victimization in schools and care for students who have been victimized;specific measures include cultivating empathy,teaching defending skills that have been found to help reduce the adverse effects of victimization,and encouraging prosocial behavior during children's socialization development.展开更多
Internet gaming disorder(IGD)among junior high school students is an increasingly prominent mental health concern.It is important to look for influences behind internet gaming disorder tendency(IGDT)in the junior high...Internet gaming disorder(IGD)among junior high school students is an increasingly prominent mental health concern.It is important to look for influences behind internet gaming disorder tendency(IGDT)in the junior high school student population.The present study aimed to reveal the explanatory mechanisms underlying the association between parental psychological control(PPC)and internet gaming disorder tendency among junior high school students by testing the mediating role of core self-evaluation(CSE)and the moderating role of intentional self-regulation(ISR).Participants in present study were 735 Chinese junior high school students who completed offline self-report questionnaires on parental psychological control,core self-evaluation,intentional self-regulation,and Internet gaming disorder tendency.Analyses were conducted via mediation and moderated mediation.The results showed that:(1)Parental psychological control was positively related to junior high school students’Internet gaming disorder tendency.Core self-evaluation,and intentional self-regulation were negatively related to junior high school students’Internet gaming disorder tendency,respectively.(2)Core self-evaluation partially mediated the relationship between parental psychological control and junior high school students’Internet gaming disorder tendency.(3)Intentional self-regulation moderated the association between parental psychological control and Internet gaming disorder tendency,as well as the relationships between parental psychological control and core self-evaluation and core self-evaluation and Internet gaming disorder tendency in the mediated model.Based on these findings,we believe that there is a need to weaken parental psychological control,strengthen junior high school students’core self-evaluation and intentional self-regulation,and to recognize the important role of parents as well as their children’s personal positive traits in the healthy development of junior high school students.展开更多
In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials ...In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials and their self-heating characteristics were measured in laboratory. Furthermore, the measured temperature was studied by integrating wavelet transform, nonlinear characteristic parameters extraction and fuzzy comprehensive evaluation. The results indicate that only the ore samples 1, 2, 6 and 9 have obvious self-heating phenomenon, and their self-heating initiative temperatures are 220 ℃, 239 ℃, 220 ℃ and 220 ℃, respectively, which means that they are difficult to produce self-heating under normal mining conditions. The correlation dimension of self-heating process is fraction and the maximum Lyapunov exponent is positive, which means that it is feasible to study the self-heating process based on chaotic dynamics theory. The nonlinearities of self-heating process of these four samples （ore samples 1, 2, 6 and 9） are 0.8227, 0.7521, 0.9401 and 0.8827 respectively and the order of the samples according to these results is： sample 6, sample 9, sample 1, sample 2, which is consistent with the measured results of self-heating characteristics. Therefore, the nonlinearity method can be used to evaluate the self-heating tendency of sulfide ores, and it is an effective verification of the reliability of measured results.展开更多
In this study,numerical experiments with different initial radius of maximum wind(RMW)are performed to study the effects of tropical cyclone(TC)size combined with land-sea contrast on TC motion and low-level wind stru...In this study,numerical experiments with different initial radius of maximum wind(RMW)are performed to study the effects of tropical cyclone(TC)size combined with land-sea contrast on TC motion and low-level wind structure before landfall.By idealized numerical simulations,we found that larger TC arrived coastline earlier than smaller TC,when they started moving from the same position.This is because that the larger TCs not only accelerate earlier but also have greater movement speed than smaller TCs when they approach the coastline.The mechanism responsible for this is that the edge of large TCs reach coastline earlier,thus their movement speed accelerated earlier than small TCs,due to the asymmetries in diabatic heating and radial flow generated by the land-sea contrast.Moreover,when TCs in three experiments all affected by the land-sea contrast,the stronger asymmetries generated in larger TC,thus resulting in faster movement in larger TC.The stronger inflow in western quadrant and weaker inflow(even outflow)in eastern quadrant of larger TC deduced apparently difference in vertical motion and diabatic heating between western and eastern quadrant of TC before landfall.An analysis of potential vorticity tendency proved that the diabatic heating terms were important and considered in determining the TC landward drift because asymmetries in vertical motion and relative vorticity developed due to asymmetric flow.展开更多
A numerical simulation was performed using the Thompson microphysics scheme to preliminarily investigate the features of the microphysical processes involved in the record-breaking rainfall event that occurred in Hena...A numerical simulation was performed using the Thompson microphysics scheme to preliminarily investigate the features of the microphysical processes involved in the record-breaking rainfall event that occurred in Henan Province,China,on 20 July 2021.The simulation results showed that a strong meso-𝛾-scale vortical updraft was concurrent with the torrential rainfall.The main finding is that this event was characterized by typical midlatitude warm-rain processes.The simulation with the Thompson microphysics scheme further indicated that highly efficient collision-coalescence of cloud water to rainwater resulted in a considerably active rain droplet growth,leading to this record-breaking rainfall event.展开更多
Cold-surge events can lead to temperature drops and strong winds,which then leads to upper-ocean cooling and deepening of the mixed-layer depth,as illustrated in previous studies.In this study,based on the temperature...Cold-surge events can lead to temperature drops and strong winds,which then leads to upper-ocean cooling and deepening of the mixed-layer depth,as illustrated in previous studies.In this study,based on the temperature drop of Shanwei meteorological station,two extreme cold surges and five weak cold invasions in the South China Sea are simulated using an ocean-atmosphere coupled model to investigate their different impacts on the upper-ocean temperature.The diffusion term contributes to the difference in temperature tendency of the upper 20 m,while the advection term contributes to the positive difference from 20 to 80 m of the offshore region and negative difference from 80 to 160 m.In addition,the significant differences are attributed primarily to the influence of the upper-ocean temperature gradient,which subsequently impacts the advection term and results in notable differences in temperature tendency at depths from 80 to 160 m.展开更多
Sense and Sensibility and Persuasion is Jane Austen's first and last published works respectively, which are read widely all over the world. Austen proclaims that feeling should be governed by reason in Sense and ...Sense and Sensibility and Persuasion is Jane Austen's first and last published works respectively, which are read widely all over the world. Austen proclaims that feeling should be governed by reason in Sense and Sensibility and that reason should be compatible with feeling in Persuasion. This paper attempts to explore romantic tendency in Austen's works according to the comparison and contrast between her two novels. Through comparison and contrast, we can see the transformation of Marianne from a lady of sensibility to a sensible lady and the growth of Anne into a lady with romance.展开更多
It is true that some important feminist literary theories apply to Hotel du Lac,which illustrates clearly Brookner’s deep concern over modern women’s predicament in favor of their interests,and thus proves her stron...It is true that some important feminist literary theories apply to Hotel du Lac,which illustrates clearly Brookner’s deep concern over modern women’s predicament in favor of their interests,and thus proves her strong tendency to feminism.And then it is pointed out that the reason for Brookner’s perverse attitude toward feminism mainly lies in her unwillingness to confine herself to the category of feminism and actually Brookner has transcended the more stereotypical feminism.展开更多
According to the precipitation sequence of Beijing City from 1900 to 1958,the precipitation sequence of Chengde City were revised and extended.Then the precipitation sequence of Chaoyang City were revised and extended...According to the precipitation sequence of Beijing City from 1900 to 1958,the precipitation sequence of Chengde City were revised and extended.Then the precipitation sequence of Chaoyang City were revised and extended with the precipitation sequence of Chengde City to form 100-years precipitation sequence of Chaoyang.The results showed that the 100-years precipitation sequence of Chaoyang indicated a decreasing trend and obvious periodic variation with the change of age.That is,a 10-year rainy period (approximately 525.0 mm) appeared every 30 a,while the 30-year drought period was approximately 460.0 mm,65.0 mm lower than the former.Moreover,an obviously heavy drought lasting for 2-4 a appeared every 20 a.展开更多
The present study uses the nonlinear singular vector(NFSV)approach to identify the optimally-growing tendency perturbations of the Weather Research and Forecasting(WRF)model for tropical cyclone(TC)intensity forecasts...The present study uses the nonlinear singular vector(NFSV)approach to identify the optimally-growing tendency perturbations of the Weather Research and Forecasting(WRF)model for tropical cyclone(TC)intensity forecasts.For nine selected TC cases,the NFSV-tendency perturbations of the WRF model,including components of potential temperature and/or moisture,are calculated when TC intensities are forecasted with a 24-hour lead time,and their respective potential temperature components are demonstrated to have more impact on the TC intensity forecasts.The perturbations coherently show barotropic structure around the central location of the TCs at the 24-hour lead time,and their dominant energies concentrate in the middle layers of the atmosphere.Moreover,such structures do not depend on TC intensities and subsequent development of the TC.The NFSV-tendency perturbations may indicate that the model uncertainty that is represented by tendency perturbations but associated with the inner-core of TCs,makes larger contributions to the TC intensity forecast uncertainty.Further analysis shows that the TC intensity forecast skill could be greatly improved as preferentially superimposing an appropriate tendency perturbation associated with the sensitivity of NFSVs to correct the model,even if using a WRF with coarse resolution.展开更多
The Ms ≥ 8.0 strong earthquakes occurring in Chile since 1800 were analyzed using the ternary, quaternary, and quinary commensurability methods and the butterfly structure diagram, and it was believed that the earthq...The Ms ≥ 8.0 strong earthquakes occurring in Chile since 1800 were analyzed using the ternary, quaternary, and quinary commensurability methods and the butterfly structure diagram, and it was believed that the earthquake signal in Chile in 2014 is relatively strong, a large earthquake is likely to occur in Chile in 2014. An analysis of spatial epicenter migrations showed that the longitudinal and latitudinal epicenter migra- tions have symmetry and synchronism, and there were five obvious northward migrations and four southward migrations. The symmetry axis of the longitudinal migrations is at about 71.7°W and that of the latitudinal mi- grations is at about 30°S; these spatial symmetry axes are located at the subduction zone on the western margin of South America, where two major plates （the Nazca Plate and the South American Plate） converge.展开更多
The hot cracking tendency of 7075 semi-solid alloy under different conditions was studied by critical diameter method.The experiment and simulation results show that the dendrite arms of the rod grow from the edge to ...The hot cracking tendency of 7075 semi-solid alloy under different conditions was studied by critical diameter method.The experiment and simulation results show that the dendrite arms of the rod grow from the edge to the center.The smaller the diameter of the rod is,the more obvious the directional growth of dendrite is,and the greater the tendency of hot cracking is.Compared with ordinary melt,for semi-solid slurry,increasing mould temperature or decreasing pouring temperature can significantly decrease hot cracking tendency of 7075 alloy,decreasing hot cracking grade from 256 to 100 mm^2.Furthermore,based on the RDG criterion,the effects of solidification conditions on the hot cracking tendency were discussed combined with simulation.At the same time,the application and development of RDG criterion were also researched.展开更多
High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave a...High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave at 300 -C for 1 h,and the treated coals were analyzed,along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR).Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF)for evaluating the ash slagging and fouling tendency.Apart from this,FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures.The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP.The moisture,oxygen and sulfur of the hydrothermally treated coals decline obviously,while the calorific value rises sharply.HTP could reduce the alkali species to less than 2%(%,by weight,equivalent to Na2O in dry ash),with a maximum removal ratio of 88.9%,lowering the ash slagging and fouling tendency.The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.展开更多
基金financially supported by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(Grant No.SKLGP2020Z007)。
文摘Deeply buried mountain tunnels are often exposed to the risk of rock bursts,which always cause serious damage to the supporting structures and threaten the safety of the engineers.Due to the limited data available,a suitable approach to predict the rockburst tendency at the preliminary stage becomes very important.In this study,an integrated methodology combining 3D initial stress inversion and rockburst tendency prediction was developed and subsequently applied to a case study of the Sangzhuling Tunnel on the Sichuan–Tibet Railway.The numerical modelling involved inverting the initial stress field using a multiple linear regression method.The tunnel excavation was simulated separately by FDM and DEM,based on a stress boundary condition from the inverted stress field.The comparative analysis demonstrates that the rockburst ratio calculated using DEM(76.70%)exhibits a slight increase compared to FDM(75.38%),and the rockburst location is consistent with the actual situation.This suggests that DEM is more suitable for simulating the stress redistribution during excavation in a jointed rock mass.The numerical simulation combined with the deviatoric stress approach effectively predicts rockburst tendency,meeting the engineering requirements.Despite its limitations,numerical simulation remains a reliable method for predicting rock bursts.
基金Project(52274130)supported by the National Natural Science Foundation of ChinaProject(ZR2024ZD22)supported by the Major Basic Research Project of the Shandong Provincial Natural Science Foundation,China+1 种基金Project(2023375)supported by the Guizhou University Research and Innovation Team,ChinaProject(LH[2024]-026)supported by the Guizhou Science and Technology Plan Project,China。
文摘To investigate the mechanical response during failure and the impact tendency characteristics of gangue-coal combined structure,uniaxial compression tests were conducted on nine groups of combined structures,each with varying gangue thicknesses and positions.The response patterns of compressive strength,elastic modulus,pre-peak accumulated energy,elastic energy index,and impact energy index were systematically analyzed.Furthermore,a new index for evaluating the impact tendency of gangue-containing coal was proposed,and its effectiveness was verified.The findings are as follows:(1)As the gangue thickness increases,both the compressive strength and the pre-peak energy of the combined structure decrease,whereas the elastic modulus increases accordingly.When the gangue is located in the lower middle position,the combined structure exhibits the lowest compressive strength and elastic modulus but the highest pre peak energy.(2)As the gangue shifts toward the middle position of the combined structure,the failure mode gradually transitions from comple te“crushing”failure to an incomplete“point-type”failure.As gangue thickness further increases,the failure region evolves from overall failure to localized failure,with the degree of failure shifting from complete to incomplete.The K_(crc)value corresponding to“crushing”complete failure is higher and has a stronger impact tendency compared to“point-type”incomplete failure.(3)The proposed comprehensive impact instability evaluation index K_(crc)for the gangue-coal combined structure has shown a significant positive correlation with compressive strength(R_(c))and impact energy index(K_(E)),further verifyi ng its rationality in comprehensively assessing the impact tendency of gangue-containing coal bodies.Applying this index to the evaluation of gangue-containing coal seams provides a more accurate reflection of their impact tendency compared with the residual energy index,which has a wide range of potential applications and practical significance.
基金sponsored by the funding of the National Natural Science Foundation of China(Grant Nos.42075011,42192552,42005025,and 42075035).
文摘The synoptic process of a super Arctic cyclone in August 2016(AC16)is investigated based on the Weather Research and Forecasting(WRF)model,and the key factors affecting the rapid intensification(RI)of AC16 and their relative contributions are analyzed by diagnosing a new surface pressure tendency equation(SPTE).The major physical mechanisms behind the two RI stages of AC16 are revealed.The trajectory,intensity changes,and structural characteristics of AC16 are well simulated by the WRF model.A diagnosis based on the SPTE promisingly reproduces the two RI stages of AC16.The leading factor that influenced the intensity of AC16 was identified to be the air-column potential temperature tendency,while the pressure change at the upper boundary had less of an impact.Further analysis reveals that the horizontal potential temperature advection was the decisive factor in a warming of the air column.Specifically,the upper-level warm advection generated by the strong wind field of the upper-level jet played a dominant role in warming the air column,which caused the initial RI of AC16.The AC16 movement into a strong potential temperature gradient generated by tropopause polar vortices increased the upper-level warm advection,which warmed the air column and thereby induced the second RI of AC16.However,the net effect of vertical potential temperature advection and latent heating,as well as radiation processes,caused a cooling of the air column and thereby negatively contributed to the RI of AC16.
基金financial support for this work provided by the National Natural Science Foundation of China (No.52227901)。
文摘To evaluate the accuracy of rockburst tendency classification in coal-bearing sandstone strata,this study conducted uniaxial compression loading and unloading tests on sandstone samples with four distinct grain sizes.The tests involved loading the samples to 60%,70%,and 80%of their uniaxial compressive strength,followed by unloading and reloading until failure.Key parameters such as the elastic energy index and linear elasticity criteria were derived from these tests.Additionally,rock fragments were collected to calculate their initial ejection kinetic energy,serving as a measure of rockburst tendency.The classification of rockburst tendency was conducted using grading methods based on burst energy index(WET),pre-peak stored elastic energy(PES)and experimental observations.Multi-class classification and regression analyses were applied to machine learning models using experimental data to predict rockburst tendency levels.A comparative analysis of models from two libraries revealed that the Random Forest model achieved the highest accuracy in classification,while the Ada Boost Regressor model excelled in regression predictions.This study highlights that on a laboratory scale,integrating ejection kinetic energy with the unloading ratio,failure load,W_(ET)and PES through machine learning offers a highly accurate and reliable approach for determining rockburst tendency levels.
基金Supported by the National Natural Science Foundation of China(52304203,52374180 and 52327804).
文摘In order to study the mechanics,acoustic emission(AE)and electromagnetic emission(EME)response law of bursting liability coal at different loading rates,uniaxial compression tests were carried out on coal mass from Konggu Coal Mine.The corresponding relations among mechanical properties,AE and EME signals in the process of coal failure under loading were analyzed,and the energy evolution law of coal failure with bursting liability under loading rate was discussed.The results show that within a certain range of loading rate,the higher the loading rate,the higher the compressive strength and peak load of bursting liability coal,and the shorter the time for coal to reach the peak load.Under different loading rates,the mechanics,AE and EME signals of coal samples can be well corresponded.When the loading rate is low,the number of blocks destroyed of coal sample is large and the block size is relatively small,and the blocks are mainly scattered around the test platform.When the loading rate is high,the number of damaged blocks is relatively small and the block size is relatively large,and the blocks are far away from the test bench.When loading at a low rate,the internal cracks in coal can be fully developed and connected,and the energy release rate is relatively uniform in the process of loading and failure of coal sample.In the case of high loading rate,the energy release rate of coal sample in the loading process is much smaller than that in the moment of failure.Combining the above test results with the actual situation of the working face,it can be concluded that the total energy stored in the coal of fast mining increases and the threshold of impact decreases compared with that of slow mining.Therefore,under the disturbance of external dynamic load,rapid mining is more likely to induce rock burst.
基金financially supported by the President's Foundation of the China Academy of Engineering Physics(No.YZJJLX2018003)the Joint Funds of the National Natural Science Foundation of China(No.U1930120)the National Natural Science Foundation of China(No.12275245)。
文摘Sustainable clean energy is gradually replacing traditional fossil energy sources in important industrial applications and is placing higher demands on the technologies of energy storage and transportation.The development of multi-principal element alloys(MPEAs)offers a new idea for safe solid-state hydrogen storage materials.Owing to the unique characteristics of complex components and severe lattice distortion,MPEAs are predicted to have better hydrogen storage performance and more probability for modulation and enhancement,allowing them to meet the requirements of different hydrogen storage applications.The unique structure characteristic potentially devotes the improvement of thermodynamic and kinetic performance,such as the hydrogen storage capacity and hydrogen adsorption/desorption properties.Recently,several important modulation factors originating from components and structures facilitate the understanding of the correlation between hydrogen storage properties and microstructure.Here,we highlight the correlations of hydrogen storage mechanism,with the degree of lattice distortion,the element variation or segregation and valence electron concentration.Moreover,the development tendency on the hydrogen storage mechanism based on the advanced microscopy and computational approach is proposed.Especially,the chemically short-range ordered structure in MPEAs is predicted as a potential modification factor of the hydrogen/tritium storage properties.
基金supported by the Philosophy and Social Science Foundation of Hunan Province(Grant Number 21YBQ005).
文摘Objectives:This study investigates the association between victimization experience and the tendency to defend on behalf of victims during school bullying incidents in public settings,with a focus on the mediating effect of empathy and the moderating role of school level among Chinese children and adolescents.Methods:Data were collected by a cross-sectional survey.A total of 1491 students in Grades 4–11 participated(Boys=52.8%;Mean_(age)=13.00 years,Standard Deviation_(age)=2.31).Structural equation modeling is employed to test the hypotheses.Results:The results indicate that empathy measures partially mediate the relationship between victimization experience and defending tendency in public in-school bullying situations.In particular,individuals with a history of victimization typically demonstrate lower levels of empathy.They are less likely to protect victims in school bullying situations in the presence of others,which suggests that empathy plays a significant mediating role in this relationship.Group differences were found between primary and secondary school students,which indicates that the hypothesized model should be considered through a developmental perspective.Conclusions:The findings of this study emphasize the importance of children’s benign peer relationships,and practitioners are encouraged to prevent victimization in schools and care for students who have been victimized;specific measures include cultivating empathy,teaching defending skills that have been found to help reduce the adverse effects of victimization,and encouraging prosocial behavior during children's socialization development.
基金supported by the National Social Science Foundation of China(20BSH131).
文摘Internet gaming disorder(IGD)among junior high school students is an increasingly prominent mental health concern.It is important to look for influences behind internet gaming disorder tendency(IGDT)in the junior high school student population.The present study aimed to reveal the explanatory mechanisms underlying the association between parental psychological control(PPC)and internet gaming disorder tendency among junior high school students by testing the mediating role of core self-evaluation(CSE)and the moderating role of intentional self-regulation(ISR).Participants in present study were 735 Chinese junior high school students who completed offline self-report questionnaires on parental psychological control,core self-evaluation,intentional self-regulation,and Internet gaming disorder tendency.Analyses were conducted via mediation and moderated mediation.The results showed that:(1)Parental psychological control was positively related to junior high school students’Internet gaming disorder tendency.Core self-evaluation,and intentional self-regulation were negatively related to junior high school students’Internet gaming disorder tendency,respectively.(2)Core self-evaluation partially mediated the relationship between parental psychological control and junior high school students’Internet gaming disorder tendency.(3)Intentional self-regulation moderated the association between parental psychological control and Internet gaming disorder tendency,as well as the relationships between parental psychological control and core self-evaluation and core self-evaluation and Internet gaming disorder tendency in the mediated model.Based on these findings,we believe that there is a need to weaken parental psychological control,strengthen junior high school students’core self-evaluation and intentional self-regulation,and to recognize the important role of parents as well as their children’s personal positive traits in the healthy development of junior high school students.
基金Project(51304238)supported by the National Natural Science Foundation of ChinaProject(JSK200206)supported by the Foundation of Key Laboratory of Mine Thermo-motive Disaster and Prevention,Ministry of Education,China
文摘In order to reveal the nonlinear dynamics characteristics of unsteady self-heating process of sulfide ores, nine different kinds of sulfide ore samples from a pyrite mine in China were taken as experimental materials and their self-heating characteristics were measured in laboratory. Furthermore, the measured temperature was studied by integrating wavelet transform, nonlinear characteristic parameters extraction and fuzzy comprehensive evaluation. The results indicate that only the ore samples 1, 2, 6 and 9 have obvious self-heating phenomenon, and their self-heating initiative temperatures are 220 ℃, 239 ℃, 220 ℃ and 220 ℃, respectively, which means that they are difficult to produce self-heating under normal mining conditions. The correlation dimension of self-heating process is fraction and the maximum Lyapunov exponent is positive, which means that it is feasible to study the self-heating process based on chaotic dynamics theory. The nonlinearities of self-heating process of these four samples （ore samples 1, 2, 6 and 9） are 0.8227, 0.7521, 0.9401 and 0.8827 respectively and the order of the samples according to these results is： sample 6, sample 9, sample 1, sample 2, which is consistent with the measured results of self-heating characteristics. Therefore, the nonlinearity method can be used to evaluate the self-heating tendency of sulfide ores, and it is an effective verification of the reliability of measured results.
基金The National Natural Science Foundation of China under contract Nos 42175011,42192554,and 42305007.
文摘In this study,numerical experiments with different initial radius of maximum wind(RMW)are performed to study the effects of tropical cyclone(TC)size combined with land-sea contrast on TC motion and low-level wind structure before landfall.By idealized numerical simulations,we found that larger TC arrived coastline earlier than smaller TC,when they started moving from the same position.This is because that the larger TCs not only accelerate earlier but also have greater movement speed than smaller TCs when they approach the coastline.The mechanism responsible for this is that the edge of large TCs reach coastline earlier,thus their movement speed accelerated earlier than small TCs,due to the asymmetries in diabatic heating and radial flow generated by the land-sea contrast.Moreover,when TCs in three experiments all affected by the land-sea contrast,the stronger asymmetries generated in larger TC,thus resulting in faster movement in larger TC.The stronger inflow in western quadrant and weaker inflow(even outflow)in eastern quadrant of larger TC deduced apparently difference in vertical motion and diabatic heating between western and eastern quadrant of TC before landfall.An analysis of potential vorticity tendency proved that the diabatic heating terms were important and considered in determining the TC landward drift because asymmetries in vertical motion and relative vorticity developed due to asymmetric flow.
基金jointly supported by the National Natural Science Foundation of China[grant numbers U2342202 and 42175005]the Qing Lan Project[grant number R2023Q06]。
文摘A numerical simulation was performed using the Thompson microphysics scheme to preliminarily investigate the features of the microphysical processes involved in the record-breaking rainfall event that occurred in Henan Province,China,on 20 July 2021.The simulation results showed that a strong meso-𝛾-scale vortical updraft was concurrent with the torrential rainfall.The main finding is that this event was characterized by typical midlatitude warm-rain processes.The simulation with the Thompson microphysics scheme further indicated that highly efficient collision-coalescence of cloud water to rainwater resulted in a considerably active rain droplet growth,leading to this record-breaking rainfall event.
基金jointly supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number SML2023SP240]the National Natural Science Foundation of China[grant number 92158204]。
文摘Cold-surge events can lead to temperature drops and strong winds,which then leads to upper-ocean cooling and deepening of the mixed-layer depth,as illustrated in previous studies.In this study,based on the temperature drop of Shanwei meteorological station,two extreme cold surges and five weak cold invasions in the South China Sea are simulated using an ocean-atmosphere coupled model to investigate their different impacts on the upper-ocean temperature.The diffusion term contributes to the difference in temperature tendency of the upper 20 m,while the advection term contributes to the positive difference from 20 to 80 m of the offshore region and negative difference from 80 to 160 m.In addition,the significant differences are attributed primarily to the influence of the upper-ocean temperature gradient,which subsequently impacts the advection term and results in notable differences in temperature tendency at depths from 80 to 160 m.
文摘Sense and Sensibility and Persuasion is Jane Austen's first and last published works respectively, which are read widely all over the world. Austen proclaims that feeling should be governed by reason in Sense and Sensibility and that reason should be compatible with feeling in Persuasion. This paper attempts to explore romantic tendency in Austen's works according to the comparison and contrast between her two novels. Through comparison and contrast, we can see the transformation of Marianne from a lady of sensibility to a sensible lady and the growth of Anne into a lady with romance.
文摘It is true that some important feminist literary theories apply to Hotel du Lac,which illustrates clearly Brookner’s deep concern over modern women’s predicament in favor of their interests,and thus proves her strong tendency to feminism.And then it is pointed out that the reason for Brookner’s perverse attitude toward feminism mainly lies in her unwillingness to confine herself to the category of feminism and actually Brookner has transcended the more stereotypical feminism.
文摘According to the precipitation sequence of Beijing City from 1900 to 1958,the precipitation sequence of Chengde City were revised and extended.Then the precipitation sequence of Chaoyang City were revised and extended with the precipitation sequence of Chengde City to form 100-years precipitation sequence of Chaoyang.The results showed that the 100-years precipitation sequence of Chaoyang indicated a decreasing trend and obvious periodic variation with the change of age.That is,a 10-year rainy period (approximately 525.0 mm) appeared every 30 a,while the 30-year drought period was approximately 460.0 mm,65.0 mm lower than the former.Moreover,an obviously heavy drought lasting for 2-4 a appeared every 20 a.
基金jointly sponsored by the National Key Research and Development Program of China (Grant No. 2018YFC1506402)the National Natural Science Foundation of China (Grant Nos. 41930971, 41575061 and 41775061)
文摘The present study uses the nonlinear singular vector(NFSV)approach to identify the optimally-growing tendency perturbations of the Weather Research and Forecasting(WRF)model for tropical cyclone(TC)intensity forecasts.For nine selected TC cases,the NFSV-tendency perturbations of the WRF model,including components of potential temperature and/or moisture,are calculated when TC intensities are forecasted with a 24-hour lead time,and their respective potential temperature components are demonstrated to have more impact on the TC intensity forecasts.The perturbations coherently show barotropic structure around the central location of the TCs at the 24-hour lead time,and their dominant energies concentrate in the middle layers of the atmosphere.Moreover,such structures do not depend on TC intensities and subsequent development of the TC.The NFSV-tendency perturbations may indicate that the model uncertainty that is represented by tendency perturbations but associated with the inner-core of TCs,makes larger contributions to the TC intensity forecast uncertainty.Further analysis shows that the TC intensity forecast skill could be greatly improved as preferentially superimposing an appropriate tendency perturbation associated with the sensitivity of NFSVs to correct the model,even if using a WRF with coarse resolution.
基金supported by the National Natural Science Foundation of China(41171090)the Graduate Student Innovation Foundation of Shaanxi Normal University
文摘The Ms ≥ 8.0 strong earthquakes occurring in Chile since 1800 were analyzed using the ternary, quaternary, and quinary commensurability methods and the butterfly structure diagram, and it was believed that the earthquake signal in Chile in 2014 is relatively strong, a large earthquake is likely to occur in Chile in 2014. An analysis of spatial epicenter migrations showed that the longitudinal and latitudinal epicenter migra- tions have symmetry and synchronism, and there were five obvious northward migrations and four southward migrations. The symmetry axis of the longitudinal migrations is at about 71.7°W and that of the latitudinal mi- grations is at about 30°S; these spatial symmetry axes are located at the subduction zone on the western margin of South America, where two major plates （the Nazca Plate and the South American Plate） converge.
基金Project(17YF1407100)supported by the Shanghai Sailing Program of ChinaProject(17PJ1408600)supported by Shanghai Pujiang Program of China
文摘The hot cracking tendency of 7075 semi-solid alloy under different conditions was studied by critical diameter method.The experiment and simulation results show that the dendrite arms of the rod grow from the edge to the center.The smaller the diameter of the rod is,the more obvious the directional growth of dendrite is,and the greater the tendency of hot cracking is.Compared with ordinary melt,for semi-solid slurry,increasing mould temperature or decreasing pouring temperature can significantly decrease hot cracking tendency of 7075 alloy,decreasing hot cracking grade from 256 to 100 mm^2.Furthermore,based on the RDG criterion,the effects of solidification conditions on the hot cracking tendency were discussed combined with simulation.At the same time,the application and development of RDG criterion were also researched.
基金the National Key Basic Research Program of China (No. 2014CB238905)
文摘High-alkali species in coal are notorious for causing ash slagging and fouling incidents.In this paper,four high-alkali coals were individually subject to hydrothermal pretreatment(HTP),within a batch-type autoclave at 300 -C for 1 h,and the treated coals were analyzed,along with the oxygen-containing functional groups determined by Fourier transform infrared spectrometer(FT-IR).Then the alkali species and other components in the coal ash were quantified by X-ray fluorescence(XRF)for evaluating the ash slagging and fouling tendency.Apart from this,FactSage was adopted to simulate the occurrence and transformation of alkali species during coal thermal conversion ending at various temperatures.The findings indicate that the treated coals are superior to the parent ones in terms of certain remarkable changes via HTP.The moisture,oxygen and sulfur of the hydrothermally treated coals decline obviously,while the calorific value rises sharply.HTP could reduce the alkali species to less than 2%(%,by weight,equivalent to Na2O in dry ash),with a maximum removal ratio of 88.9%,lowering the ash slagging and fouling tendency.The proposed mechanism of HTP was that the alkali species in coal matrix became released due to the breakage of the coal functional groups and micropores during HTP.
