To review the rockburst proneness(or tendency)criteria of rock materials and compare the judgment accuracy of them,twenty criteria were summarized,and their judgment accuracy was evaluated and compared based on the la...To review the rockburst proneness(or tendency)criteria of rock materials and compare the judgment accuracy of them,twenty criteria were summarized,and their judgment accuracy was evaluated and compared based on the laboratory tests on fourteen types of rocks.This study begins firstly by introducing the twenty rockburst proneness criteria,and their origins,definitions,calculation methods and grading standards were summarized in detail.Subsequently,to evaluate and compare the judgment accuracy of the twenty criteria,a series of laboratory tests were carried out on fourteen types of rocks,and the rockburst proneness judgment results of the twenty criteria for the fourteen types of rocks were obtained accordingly.Moreover,to provide a unified basis for the judgment accuracy evaluation of above criteria,a classification standard(obtained according to the actual failure results and phenomena of rock specimen)of rockburst proneness in laboratory tests was introduced.The judgment results of the twenty criteria were compared with the judgment results of this classification standard.The results show that the judgment results of the criterion based on residual elastic energy(REE)index are completely consistent with the actual rockburst proneness,and the other criteria have some inconsistent situations more or less.Moreover,the REE index is based on the linear energy storage law and defined in form of a difference value and considered the whole failure process,and these superior characteristics ensure its accuracy.It is believed that the criterion based on REE index is comparatively more accurate and scientific than other criteria,and it can be recommended to be applied to judge the rockburst proneness of rock materials.展开更多
Brittleness is an important parameter controlling the mechanical behavior and failure characteristics of rocks under loading and unloading conditions,such as fracability,cutability,drillability and rockburst proneness...Brittleness is an important parameter controlling the mechanical behavior and failure characteristics of rocks under loading and unloading conditions,such as fracability,cutability,drillability and rockburst proneness.As such,it is of high practical value to correctly evaluate rock brittleness.However,the definition and measurement method of rock brittleness have been very diverse and not yet been standardized.In this paper,the definitions of rock brittleness are firstly reviewed,and several representative definitions of rock brittleness are identified and briefly discussed.The development and role of rock brittleness in different fields of rock engineering are also studied.Eighty brittleness indices publicly available in rock mechanics literature are compiled,and the measurement method,applicability and limitations of some indices are discussed.The results show that(1)the large number of brittleness indices and brittleness definitions is attributed to the different foci on the rock behavior when it breaks;(2)indices developed in one field usually are not directly applicable to other fields;and(3)the term“brittleness”is sometimes misused,and many empirically-obtained brittleness indices,which lack theoretical basis,fail to truly reflect rock brittleness.On the basis of this review,three measurement methods are identified,i.e.(1)elastic deformation before fracture,(2)shape of post-peak stressestrain curves,and(3)methods based on fracture mechanics theory,which have the potential to be further refined and unified to become the standard measurement methods of rock brittleness.It is highly beneficial for the rock mechanics community to develop a robust definition of rock brittleness.This study will undoubtedly provide a comprehensive timely reference for selecting an appropriate brittleness index for their applications,and will also pave the way for the development of a standard definition and measurement method of rock brittleness in the long term.展开更多
Rock burst is a severe disaster in mining and underground engineering,and it is important to predict the rock burst risk for minimizing the loss during the constructing process.The rock burst proneness was connected w...Rock burst is a severe disaster in mining and underground engineering,and it is important to predict the rock burst risk for minimizing the loss during the constructing process.The rock burst proneness was connected with the acoustic emission(AE) parameter in this work,which contributes to predicting the rock burst risk using AE technique.Primarily,a rock burst proneness index is proposed,and it just depends on the heterogeneous degree of rock material.Then,the quantificational formula between the value of rock burst proneness index and the accumulative AE counts in rock sample under uniaxial compression with axial strain increases is developed.Finally,three kinds of rock samples,i.e.,granite,limestone and sandstone are tested about variation of the accumulative AE counts under uniaxial compression,and the test data are fitted well with the theoretic formula.展开更多
To investigate the influence of the bedding angle,β,on the mechanical properties and rockburst proneness,uniaxial compression tests were conducted using cylindrical phyllite specimens with different bedding angles.Ac...To investigate the influence of the bedding angle,β,on the mechanical properties and rockburst proneness,uniaxial compression tests were conducted using cylindrical phyllite specimens with different bedding angles.According to the results,the peak stress,peak strain,cumulative acoustic emission counts,and potential energy of the elastic strain exhibited a U-shaped change trend.With an increase in β from 0°to 90°,the failure mode transformed from tensile splitting failure along the bedding plane to shear slip failure along the weak bedding plane.Finally,the failure mode evolved into a tensile splitting failure across the bedding plane.When β=15°,30°,and 45°,the phyllite specimens exhibited strong,slight,and moderate rockburst proneness,with strong,slight,and moderate shear slip rockbursts,respectively.When β=0°,60°,75°,and 90°,the phyllite specimens had extremely strong rockburst proneness,and an extremely strong strain rockburst occurred.展开更多
Many underground engineering projects show that rockburst can occur in rocks at great depth and high temperature, and temperature is a critical factor affecting the intensity of rockburst. In general, temperature can ...Many underground engineering projects show that rockburst can occur in rocks at great depth and high temperature, and temperature is a critical factor affecting the intensity of rockburst. In general, temperature can affect the energy storage, dissipation, and surplus in rock. To explore the influence of temperature on the energy storage and dissipation characteristics and rockburst proneness, the present study has carried out a range of the uniaxial compression(UC) and single-cyclic loading-unloading uniaxial compression(SCLUC) tests on pre-heated granite specimens at 20℃-700℃. The results demonstrate that the rockburst proneness of pre-heated granite initially increases and subsequently decreases with the increase of temperature. The temperature of 300℃ has been found to be the threshold for rockburst proneness. Meanwhile, it is found that the elastic strain energy density increases linearly with the total input strain energy density for the pre-heated granites, confirming that the linear energy property of granite has not been altered by temperature. According to this inherent property, the peak elastic strain energy of pre-heated granites can be calculated accurately. On this basis, utilising the residual elastic energy index, the rockburst proneness of pre-heated granite can be determined quantitatively. The obtained results from high to low are: 317.9 k J/m^(3)(300℃), 264.1 k J/m^(3)(100℃), 260.6 k J/m^(3)(20℃), 235.5 k J/m^(3)(500℃), 158.9 k J/m^(3)(700℃), which are consistent with the intensity of actual rockburst for specimens. In addition, the relationship between temperature and energy storage capacity(ESC) of granite was discussed, revealing that high temperature impairs ESC of rocks, which is essential for reducing the rockburst proneness. This study provides some new insights into the rockburst proneness evaluation in high-temperature rock engineering.展开更多
To investigate the influence of confining pressure and pore water pressure on strength characteristics,energy storage state and energy release intensity at peak failure of deep sandstone,a series of triaxial compressi...To investigate the influence of confining pressure and pore water pressure on strength characteristics,energy storage state and energy release intensity at peak failure of deep sandstone,a series of triaxial compression tests under hydraulic coupling conditions are carried out.By analyzing the process of rock deformation and failure,the stress thresholds of the rock are obtained.The change trend of total energy density,elastic energy density and dissipated energy density of deep sandstone in the pre-peak stage is obtained by the graphical integration method.By comparing the dynamic energy storage level of rocks under different confining pressures,the influence of pore water pressure on the energy dissipation at stress thresholds of crack closure stress,crack initiation stress,crack damage stress and peak stress is analyzed.Based on the ratio of pre-peak total energy density to post-peak total energy density,the interaction mechanism of confining pressure and pore water pressure for the rock burst proneness of deep sandstone is studied.The experimental results show that the peak stress of sandstone increases with the increase of confining pressure,while the existence of pore water pressure can weaken the peak stress of sandstone.In the stress stage from crack closure stress to peak stress,the dynamic energy storage level of rock presents a trend of the inverse“check mark”.Meanwhile,the larger the confining pressure,the higher the energy storage level of rock.However,the pore water pressure increases the degree of energy dissipation of rock and reduces the energy storage capacity of rock,and the degree of dissipation is linear with pore water pressure.The increase of confining pressure aggravates the instability and failure of deep sandstone,while pore water pressure has the opposite effect.The research results will provide necessary data support for the stability analysis of rock mass excavation in sandstone stratum under high stress and high pore water pressure.展开更多
Frequent traffic accidents constitute a major danger to human beings.The accident-prone driver who has the stable physiological,psychological,and behavioral characteristics is one of the most prominent causes of traff...Frequent traffic accidents constitute a major danger to human beings.The accident-prone driver who has the stable physiological,psychological,and behavioral characteristics is one of the most prominent causes of traffic accidents.The internal link between the individual characteristics and the accident proneness has been a difficult point in the accident prevention research.The authors selected accident-prone drivers as cases and safe drivers as controls(case-control group) from 18,360 drivers who were enrolled from three public transportation incorporations of China using area stratified sampling method.The case-control groups were 1:1 matched.The authors performed genome-wide association study(GWAS) by 179 cases and 179 controls using the U.S.Affymetrix Genome-Wide Human Mapping SNP 6.0Array.The authors observed that the gene frequencies of34 single-nucleotide polymorphisms(SNPs) in three regions of cases were higher than those in the control(P < 10^(–4)).The authors then tested two independent replication sets for strong association 6 SNPs in 349 pairs of case-control drivers using the U.S.ABI 3730 sequencing method.The results indicated that SNP rs6069499 within linked CBLN4 gene are strongly associated with accident proneness(Pcombined= 6.37×10^(-10)).According to CBLN4 gene mainly involved in adrenal development and the regulation of secretion,the authors performed 12 biochemical parameters of the blood using radioimmunoassay.The levels of dopamine(DA) and adrenocorticotropic(ACTH)hormone showed significant differences between accidentprone drivers and safe drivers(P_(DA)= 0.03,P_(ACTH)= 0.01).It is suggested that the accident-prone drivers may have the idiosyncrasy of susceptibility.展开更多
Rockburst has perennially posed a formidable challenge to the stability of underground engineering works,particularly under conditions of deep-seated high stress.This paper provides a comprehensive review of recent ad...Rockburst has perennially posed a formidable challenge to the stability of underground engineering works,particularly under conditions of deep-seated high stress.This paper provides a comprehensive review of recent advancements in on-site research related to rockburst occurrences,covering on-site case analyses,monitoring methodologies,early warning systems,and risk(proneness)evaluation.Initially,the concepts and classifications of rockburst based on on-site understanding were summarized.The influences of structural planes(in various spatial distribution combinations),in-situ stress(particularly magnitude and direction of the principal stress),dynamic disturbances,and excavation profiles on rockburst were thoroughly assessed and discussed through the analysis of published rockburst cases and on-site survey results.Subsequently,a compendium of commonly employed on-site monitoring techniques was outlined,delineating their respective technical attributes.Particular emphasis is accorded to the efficacy of microseismic monitoring technology and its prospective utility in facilitating dynamic rockburst early warning mechanisms.Building upon this foundation,the feasibility of assessing rockburst propensity while considering on-site variables is verified,encompassing the selection and quantitative evaluation of pertinent indicators.Ultimately,a comprehensive synthesis of the paper is presented,alongside the articulation of prospective research goals for the future.展开更多
Accurate prediction of rockburst proneness is one of challenges for assessing the rockburst risk and selecting effective control measures.This study aims to assess rockburst proneness by considering the energy charact...Accurate prediction of rockburst proneness is one of challenges for assessing the rockburst risk and selecting effective control measures.This study aims to assess rockburst proneness by considering the energy characteristics and qualitative information during rock failure.Several representative rock types in cylindrical and cuboidal sample shapes were tested under uniaxial compression conditions and the failure progress was detected by a high-speed camera.The far-field ejection mass ratio(FEMR)was determined considering the qualitative failure information of the rock samples.The peak-strength energy impact index and the residual elastic energy index were used to quantitatively evaluate the rockburst proneness of both cylindrical and cuboidal samples.Further,the performance of these two indices was analyzed by comparing their estimates with the FEMR.The results show that the accuracy of the residual elastic energy index is significantly higher than that of the peak-strength energy impact index.The residual elastic energy index and the FEMR are in good agreement for both cylindrical and cuboidal rock materials.This is because these two indices can essentially reflect the common energy release mechanism characterized by the mass,ejection velocity,and ejection distance of rock fragments.It suggests that both the FEMR and the residual elastic energy index can be used to accurately measure the rockburst proneness of cylindrical and cuboidal samples based on uniaxial compression test.展开更多
A mathematical model describing the risks of road accidents has been built on the basis of statistical data of drivers’ accident rate. It has been revealed that drivers can be divided by the degree of their accident ...A mathematical model describing the risks of road accidents has been built on the basis of statistical data of drivers’ accident rate. It has been revealed that drivers can be divided by the degree of their accident proneness into four categories with sharply differing probabilities of road accidents. It has been shown that there is a possibility of classification of drivers in accordance with specified categories.展开更多
This study examined the influence of Big Five personality traits on Facebook usage and examined the interactions of traits in this context based on Torgersen’s (1995) typological approach. The effect of self-esteem, ...This study examined the influence of Big Five personality traits on Facebook usage and examined the interactions of traits in this context based on Torgersen’s (1995) typological approach. The effect of self-esteem, narcissism, loneliness, shyness and boredom proneness on Facebook usage was also investigated. The sample included both student (N = 190) and (N = 184) non-student samples. Narcissism was the strongest predictor of time spent on Facebook per day for both students and non-students. Narcissism was also the strongest predictor of number of daily logins for non-students, however, agreeableness was the strongest predictor of logins for students. Extraversion was the strongest predictor of number of Facebook friends for both students and non- students, however the interaction of Extraversion and Neuroticism was also a predictor of Facebook friends for students, and the interaction of Extraversion and Conscientiousness for non-students. Future research should consider the combined effect of personality traits on overall Facebook use.展开更多
A new method based on rough set theory and genetic algorithm was proposedto predict the rock burst proneness. Nine influencing factors were first selected, and then,the decision table was set up. Attributes were reduc...A new method based on rough set theory and genetic algorithm was proposedto predict the rock burst proneness. Nine influencing factors were first selected, and then,the decision table was set up. Attributes were reduced by genetic algorithm. Rough setwas used to extract the simplified decision rules of rock burst proneness. Taking the practical engineering for example, the rock burst proneness was evaluated and predicted bydecision rules. Comparing the prediction results with the actual results, it shows that theproposed method is feasible and effective.展开更多
Software is an important part of automotive product development, and it is commonly known that software quality assurance consumes considerable effort in safety-critical embedded software development. Increasing the e...Software is an important part of automotive product development, and it is commonly known that software quality assurance consumes considerable effort in safety-critical embedded software development. Increasing the effectiveness and efficiency of this effort thus becomes more and more important. Identifying problematic code areas which are most likely to fail and therefore require most of the quality assurance attention is required. This article presents an exploratory study investigating whether the faults detected by static analysis tools combined with code complexity metrics can be used as software quality indicators and to build pre-release fault prediction models. The combination of code complexity metrics with static analysis fault density was used to predict the pre-release fault density with an accuracy of 78.3%. This combination was also used to separate high and low quality components with a classification accuracy of 79%.展开更多
Software programs are always prone to change for several reasons. In a software product line, the change is more often as many software units are carried from one release to another. Also, other new files are added to...Software programs are always prone to change for several reasons. In a software product line, the change is more often as many software units are carried from one release to another. Also, other new files are added to the reused files. In this work, we explore the possibility of building a model that can predict files with a high chance of experiencing the change from one release to another. Knowing the files that are likely to face a change is vital because it will help to improve the planning, managing resources, and reducing the cost. This also helps to improve the software process, which should lead to better software quality. Also, we explore how different learners perform in this context, and if the learning improves as the software evolved. Predicting change from a release to the next release was successful using logistic regression, J48, and random forest with accuracy and precision scored between 72% to 100%, recall scored between 74% to 100%, and F-score scored between 80% to 100%. We also found that there was no clear evidence regarding if the prediction performance will ever improve as the project evolved.展开更多
Objective:The purpose of the current study was to determine the family environment charac-teristics of accident-prone children,and the influencing factors to provide a reference for accident prevention and interventio...Objective:The purpose of the current study was to determine the family environment charac-teristics of accident-prone children,and the influencing factors to provide a reference for accident prevention and intervention for these children.Methods:One hundred forty-seven cases of accident-prone children were screened out from a cross-sectional survey as the case group,and another 147 cases of non-accidentally-injured chil-dren served as the control group.The Chinese version of the Family Environment Scale(FES-CV)was applied to evaluate the family environment characteristics of subjects from both groups.Results:The incidence of accident-prone children was 9.42%.Comparing the scores of all factors in the FES-CV,the contradiction score of the case group was higher than the control group,while the scores of other factors was lower than the control group.Differences between the two groups with respect to intimacy,emotional expression,contradiction,independence,and success scores were statistically significant,but differences in informative and entertaining scores were not.Differences with respect to family type,financial status,education,guardian,age of guardian,marital status,and health status were statistically significant.As revealed by regression analysis,intimacy(OR=0.530),emotional expression(OR=0.749),and independence(OR=0.732)were protective factors for accident proneness,while rigorous education(OR=2.101)and indulgence or indifference/violence(OR=7.629)were risk factors for accident proneness.Conclusion:Family environment influence child accident proneness,thus preventive interventions should be provided according to the characteristics of the family environment.展开更多
基金Project(41877272)supported by the National Natural Science Foundation of ChinaProject(2020zzts715)supported by the Fundamental Research Funds for the Central Universities of Central South University,ChinaProject(2242020R10023)supported by the Fundamental Research Funds for the Central Universities of Southeast University,China。
文摘To review the rockburst proneness(or tendency)criteria of rock materials and compare the judgment accuracy of them,twenty criteria were summarized,and their judgment accuracy was evaluated and compared based on the laboratory tests on fourteen types of rocks.This study begins firstly by introducing the twenty rockburst proneness criteria,and their origins,definitions,calculation methods and grading standards were summarized in detail.Subsequently,to evaluate and compare the judgment accuracy of the twenty criteria,a series of laboratory tests were carried out on fourteen types of rocks,and the rockburst proneness judgment results of the twenty criteria for the fourteen types of rocks were obtained accordingly.Moreover,to provide a unified basis for the judgment accuracy evaluation of above criteria,a classification standard(obtained according to the actual failure results and phenomena of rock specimen)of rockburst proneness in laboratory tests was introduced.The judgment results of the twenty criteria were compared with the judgment results of this classification standard.The results show that the judgment results of the criterion based on residual elastic energy(REE)index are completely consistent with the actual rockburst proneness,and the other criteria have some inconsistent situations more or less.Moreover,the REE index is based on the linear energy storage law and defined in form of a difference value and considered the whole failure process,and these superior characteristics ensure its accuracy.It is believed that the criterion based on REE index is comparatively more accurate and scientific than other criteria,and it can be recommended to be applied to judge the rockburst proneness of rock materials.
基金We gratefully acknowledge financial support from the National Natural Science Foundation of China(Grant Nos.51879135 and 41877217)The work in this paper was also supported by the Hong Kong Scholars Program(Grant No.XJ2017043).
文摘Brittleness is an important parameter controlling the mechanical behavior and failure characteristics of rocks under loading and unloading conditions,such as fracability,cutability,drillability and rockburst proneness.As such,it is of high practical value to correctly evaluate rock brittleness.However,the definition and measurement method of rock brittleness have been very diverse and not yet been standardized.In this paper,the definitions of rock brittleness are firstly reviewed,and several representative definitions of rock brittleness are identified and briefly discussed.The development and role of rock brittleness in different fields of rock engineering are also studied.Eighty brittleness indices publicly available in rock mechanics literature are compiled,and the measurement method,applicability and limitations of some indices are discussed.The results show that(1)the large number of brittleness indices and brittleness definitions is attributed to the different foci on the rock behavior when it breaks;(2)indices developed in one field usually are not directly applicable to other fields;and(3)the term“brittleness”is sometimes misused,and many empirically-obtained brittleness indices,which lack theoretical basis,fail to truly reflect rock brittleness.On the basis of this review,three measurement methods are identified,i.e.(1)elastic deformation before fracture,(2)shape of post-peak stressestrain curves,and(3)methods based on fracture mechanics theory,which have the potential to be further refined and unified to become the standard measurement methods of rock brittleness.It is highly beneficial for the rock mechanics community to develop a robust definition of rock brittleness.This study will undoubtedly provide a comprehensive timely reference for selecting an appropriate brittleness index for their applications,and will also pave the way for the development of a standard definition and measurement method of rock brittleness in the long term.
基金Project(2010CB226804)supported by the National Basic Research Program(973 Program)of ChinaProject(11202108)supported by the National Natural Science Foundation of ChinaProject(BK20130189)supported by the Natural Science Foundation of Jiangsu Province,China
文摘Rock burst is a severe disaster in mining and underground engineering,and it is important to predict the rock burst risk for minimizing the loss during the constructing process.The rock burst proneness was connected with the acoustic emission(AE) parameter in this work,which contributes to predicting the rock burst risk using AE technique.Primarily,a rock burst proneness index is proposed,and it just depends on the heterogeneous degree of rock material.Then,the quantificational formula between the value of rock burst proneness index and the accumulative AE counts in rock sample under uniaxial compression with axial strain increases is developed.Finally,three kinds of rock samples,i.e.,granite,limestone and sandstone are tested about variation of the accumulative AE counts under uniaxial compression,and the test data are fitted well with the theoretic formula.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(Nos.51904335,11972378,41630642)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2019zzts310).
文摘To investigate the influence of the bedding angle,β,on the mechanical properties and rockburst proneness,uniaxial compression tests were conducted using cylindrical phyllite specimens with different bedding angles.According to the results,the peak stress,peak strain,cumulative acoustic emission counts,and potential energy of the elastic strain exhibited a U-shaped change trend.With an increase in β from 0°to 90°,the failure mode transformed from tensile splitting failure along the bedding plane to shear slip failure along the weak bedding plane.Finally,the failure mode evolved into a tensile splitting failure across the bedding plane.When β=15°,30°,and 45°,the phyllite specimens exhibited strong,slight,and moderate rockburst proneness,with strong,slight,and moderate shear slip rockbursts,respectively.When β=0°,60°,75°,and 90°,the phyllite specimens had extremely strong rockburst proneness,and an extremely strong strain rockburst occurred.
基金supported by the National Natural Science Foundation of China (Grant No. 41877272)the Fundamental Research Funds for the Central Universities (Grant No.2242022k30054)the Fundamental Research Funds for the Central Universities of Central South University (Grant No.2021zzts0861)。
文摘Many underground engineering projects show that rockburst can occur in rocks at great depth and high temperature, and temperature is a critical factor affecting the intensity of rockburst. In general, temperature can affect the energy storage, dissipation, and surplus in rock. To explore the influence of temperature on the energy storage and dissipation characteristics and rockburst proneness, the present study has carried out a range of the uniaxial compression(UC) and single-cyclic loading-unloading uniaxial compression(SCLUC) tests on pre-heated granite specimens at 20℃-700℃. The results demonstrate that the rockburst proneness of pre-heated granite initially increases and subsequently decreases with the increase of temperature. The temperature of 300℃ has been found to be the threshold for rockburst proneness. Meanwhile, it is found that the elastic strain energy density increases linearly with the total input strain energy density for the pre-heated granites, confirming that the linear energy property of granite has not been altered by temperature. According to this inherent property, the peak elastic strain energy of pre-heated granites can be calculated accurately. On this basis, utilising the residual elastic energy index, the rockburst proneness of pre-heated granite can be determined quantitatively. The obtained results from high to low are: 317.9 k J/m^(3)(300℃), 264.1 k J/m^(3)(100℃), 260.6 k J/m^(3)(20℃), 235.5 k J/m^(3)(500℃), 158.9 k J/m^(3)(700℃), which are consistent with the intensity of actual rockburst for specimens. In addition, the relationship between temperature and energy storage capacity(ESC) of granite was discussed, revealing that high temperature impairs ESC of rocks, which is essential for reducing the rockburst proneness. This study provides some new insights into the rockburst proneness evaluation in high-temperature rock engineering.
基金Project(2016YFC0600801)supported by the National Key Research Development Program of ChinaProject(51774021)supported by the National Natural Science Foundation of ChinaProject(2019SDZY05)supported by the Major Scientific and Technological Innovation Project of Shandong Province,China。
文摘To investigate the influence of confining pressure and pore water pressure on strength characteristics,energy storage state and energy release intensity at peak failure of deep sandstone,a series of triaxial compression tests under hydraulic coupling conditions are carried out.By analyzing the process of rock deformation and failure,the stress thresholds of the rock are obtained.The change trend of total energy density,elastic energy density and dissipated energy density of deep sandstone in the pre-peak stage is obtained by the graphical integration method.By comparing the dynamic energy storage level of rocks under different confining pressures,the influence of pore water pressure on the energy dissipation at stress thresholds of crack closure stress,crack initiation stress,crack damage stress and peak stress is analyzed.Based on the ratio of pre-peak total energy density to post-peak total energy density,the interaction mechanism of confining pressure and pore water pressure for the rock burst proneness of deep sandstone is studied.The experimental results show that the peak stress of sandstone increases with the increase of confining pressure,while the existence of pore water pressure can weaken the peak stress of sandstone.In the stress stage from crack closure stress to peak stress,the dynamic energy storage level of rock presents a trend of the inverse“check mark”.Meanwhile,the larger the confining pressure,the higher the energy storage level of rock.However,the pore water pressure increases the degree of energy dissipation of rock and reduces the energy storage capacity of rock,and the degree of dissipation is linear with pore water pressure.The increase of confining pressure aggravates the instability and failure of deep sandstone,while pore water pressure has the opposite effect.The research results will provide necessary data support for the stability analysis of rock mass excavation in sandstone stratum under high stress and high pore water pressure.
基金supported by grants from the Research Foundation of Anhui Sanlian University
文摘Frequent traffic accidents constitute a major danger to human beings.The accident-prone driver who has the stable physiological,psychological,and behavioral characteristics is one of the most prominent causes of traffic accidents.The internal link between the individual characteristics and the accident proneness has been a difficult point in the accident prevention research.The authors selected accident-prone drivers as cases and safe drivers as controls(case-control group) from 18,360 drivers who were enrolled from three public transportation incorporations of China using area stratified sampling method.The case-control groups were 1:1 matched.The authors performed genome-wide association study(GWAS) by 179 cases and 179 controls using the U.S.Affymetrix Genome-Wide Human Mapping SNP 6.0Array.The authors observed that the gene frequencies of34 single-nucleotide polymorphisms(SNPs) in three regions of cases were higher than those in the control(P < 10^(–4)).The authors then tested two independent replication sets for strong association 6 SNPs in 349 pairs of case-control drivers using the U.S.ABI 3730 sequencing method.The results indicated that SNP rs6069499 within linked CBLN4 gene are strongly associated with accident proneness(Pcombined= 6.37×10^(-10)).According to CBLN4 gene mainly involved in adrenal development and the regulation of secretion,the authors performed 12 biochemical parameters of the blood using radioimmunoassay.The levels of dopamine(DA) and adrenocorticotropic(ACTH)hormone showed significant differences between accidentprone drivers and safe drivers(P_(DA)= 0.03,P_(ACTH)= 0.01).It is suggested that the accident-prone drivers may have the idiosyncrasy of susceptibility.
基金Project(2023YFB2603602)supported by the National Key Research and Development Program of ChinaProjects(52222810,52178383)supported by the National Natural Science Foundation of China。
文摘Rockburst has perennially posed a formidable challenge to the stability of underground engineering works,particularly under conditions of deep-seated high stress.This paper provides a comprehensive review of recent advancements in on-site research related to rockburst occurrences,covering on-site case analyses,monitoring methodologies,early warning systems,and risk(proneness)evaluation.Initially,the concepts and classifications of rockburst based on on-site understanding were summarized.The influences of structural planes(in various spatial distribution combinations),in-situ stress(particularly magnitude and direction of the principal stress),dynamic disturbances,and excavation profiles on rockburst were thoroughly assessed and discussed through the analysis of published rockburst cases and on-site survey results.Subsequently,a compendium of commonly employed on-site monitoring techniques was outlined,delineating their respective technical attributes.Particular emphasis is accorded to the efficacy of microseismic monitoring technology and its prospective utility in facilitating dynamic rockburst early warning mechanisms.Building upon this foundation,the feasibility of assessing rockburst propensity while considering on-site variables is verified,encompassing the selection and quantitative evaluation of pertinent indicators.Ultimately,a comprehensive synthesis of the paper is presented,alongside the articulation of prospective research goals for the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.41877272 and 42077244)the National Key Research and Development Program of China e 2023 Key Special Project(Grant No.2023YFC2907400).
文摘Accurate prediction of rockburst proneness is one of challenges for assessing the rockburst risk and selecting effective control measures.This study aims to assess rockburst proneness by considering the energy characteristics and qualitative information during rock failure.Several representative rock types in cylindrical and cuboidal sample shapes were tested under uniaxial compression conditions and the failure progress was detected by a high-speed camera.The far-field ejection mass ratio(FEMR)was determined considering the qualitative failure information of the rock samples.The peak-strength energy impact index and the residual elastic energy index were used to quantitatively evaluate the rockburst proneness of both cylindrical and cuboidal samples.Further,the performance of these two indices was analyzed by comparing their estimates with the FEMR.The results show that the accuracy of the residual elastic energy index is significantly higher than that of the peak-strength energy impact index.The residual elastic energy index and the FEMR are in good agreement for both cylindrical and cuboidal rock materials.This is because these two indices can essentially reflect the common energy release mechanism characterized by the mass,ejection velocity,and ejection distance of rock fragments.It suggests that both the FEMR and the residual elastic energy index can be used to accurately measure the rockburst proneness of cylindrical and cuboidal samples based on uniaxial compression test.
文摘A mathematical model describing the risks of road accidents has been built on the basis of statistical data of drivers’ accident rate. It has been revealed that drivers can be divided by the degree of their accident proneness into four categories with sharply differing probabilities of road accidents. It has been shown that there is a possibility of classification of drivers in accordance with specified categories.
文摘This study examined the influence of Big Five personality traits on Facebook usage and examined the interactions of traits in this context based on Torgersen’s (1995) typological approach. The effect of self-esteem, narcissism, loneliness, shyness and boredom proneness on Facebook usage was also investigated. The sample included both student (N = 190) and (N = 184) non-student samples. Narcissism was the strongest predictor of time spent on Facebook per day for both students and non-students. Narcissism was also the strongest predictor of number of daily logins for non-students, however, agreeableness was the strongest predictor of logins for students. Extraversion was the strongest predictor of number of Facebook friends for both students and non- students, however the interaction of Extraversion and Neuroticism was also a predictor of Facebook friends for students, and the interaction of Extraversion and Conscientiousness for non-students. Future research should consider the combined effect of personality traits on overall Facebook use.
基金Supported by the Youth Science Foundation of North China University of Water Conservancy and Electric Power(HSQJ2009016)
文摘A new method based on rough set theory and genetic algorithm was proposedto predict the rock burst proneness. Nine influencing factors were first selected, and then,the decision table was set up. Attributes were reduced by genetic algorithm. Rough setwas used to extract the simplified decision rules of rock burst proneness. Taking the practical engineering for example, the rock burst proneness was evaluated and predicted bydecision rules. Comparing the prediction results with the actual results, it shows that theproposed method is feasible and effective.
文摘Software is an important part of automotive product development, and it is commonly known that software quality assurance consumes considerable effort in safety-critical embedded software development. Increasing the effectiveness and efficiency of this effort thus becomes more and more important. Identifying problematic code areas which are most likely to fail and therefore require most of the quality assurance attention is required. This article presents an exploratory study investigating whether the faults detected by static analysis tools combined with code complexity metrics can be used as software quality indicators and to build pre-release fault prediction models. The combination of code complexity metrics with static analysis fault density was used to predict the pre-release fault density with an accuracy of 78.3%. This combination was also used to separate high and low quality components with a classification accuracy of 79%.
文摘Software programs are always prone to change for several reasons. In a software product line, the change is more often as many software units are carried from one release to another. Also, other new files are added to the reused files. In this work, we explore the possibility of building a model that can predict files with a high chance of experiencing the change from one release to another. Knowing the files that are likely to face a change is vital because it will help to improve the planning, managing resources, and reducing the cost. This also helps to improve the software process, which should lead to better software quality. Also, we explore how different learners perform in this context, and if the learning improves as the software evolved. Predicting change from a release to the next release was successful using logistic regression, J48, and random forest with accuracy and precision scored between 72% to 100%, recall scored between 74% to 100%, and F-score scored between 80% to 100%. We also found that there was no clear evidence regarding if the prediction performance will ever improve as the project evolved.
文摘Objective:The purpose of the current study was to determine the family environment charac-teristics of accident-prone children,and the influencing factors to provide a reference for accident prevention and intervention for these children.Methods:One hundred forty-seven cases of accident-prone children were screened out from a cross-sectional survey as the case group,and another 147 cases of non-accidentally-injured chil-dren served as the control group.The Chinese version of the Family Environment Scale(FES-CV)was applied to evaluate the family environment characteristics of subjects from both groups.Results:The incidence of accident-prone children was 9.42%.Comparing the scores of all factors in the FES-CV,the contradiction score of the case group was higher than the control group,while the scores of other factors was lower than the control group.Differences between the two groups with respect to intimacy,emotional expression,contradiction,independence,and success scores were statistically significant,but differences in informative and entertaining scores were not.Differences with respect to family type,financial status,education,guardian,age of guardian,marital status,and health status were statistically significant.As revealed by regression analysis,intimacy(OR=0.530),emotional expression(OR=0.749),and independence(OR=0.732)were protective factors for accident proneness,while rigorous education(OR=2.101)and indulgence or indifference/violence(OR=7.629)were risk factors for accident proneness.Conclusion:Family environment influence child accident proneness,thus preventive interventions should be provided according to the characteristics of the family environment.
