This article presents the application of an integrated method that estimates the dispersion of polycyclic aromatic hydrocarbons(PAHs)in air,and assesses the human health risk associated with PAHs inhalation.An uncerta...This article presents the application of an integrated method that estimates the dispersion of polycyclic aromatic hydrocarbons(PAHs)in air,and assesses the human health risk associated with PAHs inhalation.An uncertainty analysis method consisting of three components were applied in this study,where the three components include a bootstrapping method for analyzing the whole process associated uncertainty,an inhalation rate(IR)representation for evaluating the total PAH inhalation risk for human health,and a normally distributed absorption fraction(AF)ranging from 0%to 100%to represent the absorption capability of PAHs in human body.Using this method,an integrated process was employed to assess the health risk of the residents in Beijing,China,from inhaling PAHs in the air.The results indicate that the ambient air PAHs in Beijing is an important contributor to human health impairment,although over 68%of residents seem to be safe from daily PAH carcinogenic inhalation.In general,the accumulated daily inhalation amount is relatively higher for male and children at 10 years old of age than for female and children at 6 years old.In 1997,about 1.73%cancer sufferers in Beijing were more or less related to ambient air PAHs inhalation.At 95%confidence interval,approximately 272-309 individual cancer incidences can be attributed to PAHs pollution in the air.The probability of greater than 500 cancer occurrence is 15.3%.While the inhalation of ambient air PAHs was shown to be an important factor responsible for higher cancer occurrence in Beijing,while the contribution might not be the most significant one.展开更多
Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying availabl...Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF.展开更多
The strength of jointed rock mass is strongly controlled by the degree of interlock between its constituent rock blocks.The degree of interlock constrains the kinematic freedom of individual rock blocks to rotate and ...The strength of jointed rock mass is strongly controlled by the degree of interlock between its constituent rock blocks.The degree of interlock constrains the kinematic freedom of individual rock blocks to rotate and slide along the block forming joints.The HoekeBrown(HB)failure criterion and the geological strength index(GSI)were developed based on experiences from mine slopes and tunneling projects in moderately to poorly interlocked jointed rock masses.It has since then been demonstrated that the approach to estimate the HB strength parameters based on the GSI strength scaling equations(called the‘GSI strength equations’)tends to underestimate the confined peak strength of highly interlocked jointed rock masses(i.e.GSI>65),where the rock mass is often non-persistently jointed,and the intact rock blocks are strong and brittle.The estimation of the confined strength of such rock masses is relevant when designing mine pillars and abutments at great depths,where the confining pressure is high enough to prevent block rotation and free sliding on block boundaries.In this article,a grain-based distinct element modeling approach is used to simulate jointed rock masses of various degrees of interlock and to investigate the influences of block shape,joint persistence and joint surface condition on the confined peak strengths.The focus is on non-persistently jointed and blocky(persistently jointed)rock masses,consisting of hard and homogeneous rock blocks devoid of any strength degrading defects such as veins.The results from this investigation confirm that the GSI strength equations underestimate the confined strength of highly interlocked and non-persistently jointed rock masses.Moreover,the GSI strength equations are found to be valid to estimate the confined strength of persistently jointed rock masses with smooth and non-dilatant joint surfaces.展开更多
The COVID-19 pandemic has significantly affected global transportation mobility,presenting unprecedented challenges to transportation management.Public transit and ride-hailing services saw a drastic reduction in ride...The COVID-19 pandemic has significantly affected global transportation mobility,presenting unprecedented challenges to transportation management.Public transit and ride-hailing services saw a drastic reduction in ridership,leading to an increased inclination towards private vehicles.The pandemic also altered travel patterns and individual mobility due to various COVID-19 protocols.This study conducted a comprehensive review of 96 academic papers spanning from January 1,2020,to December 31,2022,focusing on transportation and mobility using the Scopus database.Three major themes were identified:‘Impact on Ride-Hailing Services',‘Impact on Mode Preference',and‘Impact on Trip Purpose',with subdivisions based on keywords and key findings extracted using VOSviewer.The pandemic significantly impacted ride-hailing services,altering demand,usage,and safety measures.Mode preference shifted towards private vehicles due to safety concerns.The present study underscores the long-term implications of the pandemic,emphasizing recovery strategies for ride-hailing services and mode preferences post-pandemic.It highlights the need for sustainable transportation policies,advocating for enhanced public transportation systems,promoting active travel modes,and addressing socioeconomic disparities in mobility patterns.The findings emphasize the need for resilient transportation strategies in the face of future disruptions.展开更多
Concrete comprises aggregates of various sizes bound by a cementitious paste,with Portland cement(PC)as the primary binder since the 19th century.However,PC production depletes non-renewable natural resources and caus...Concrete comprises aggregates of various sizes bound by a cementitious paste,with Portland cement(PC)as the primary binder since the 19th century.However,PC production depletes non-renewable natural resources and causes environmental degradation.Meanwhile,approximately 130 billion kilograms of cattle bones(CB)are generated globally each year,posing environmental challenges due to their non-biodegradability.CB is rich in calcium oxide,making it a potential supplementary material in cement production.This study explores the feasibility of using pretreated cattle bone ash(CBA)as a partial replacement for PC in concrete,combined with 5%silica fume and 10%fly ash.CBA was incorporated at 10%,25%,50%,and 75%by weight of cement.The results indicated that mixes containing 10%and 25%CBA achieved high-strength concrete exceeding 60 MPa after 28 d,while mixes with 50%and 75%CBA produced structural-grade concrete with strengths above 25 MPa.The findings demonstrate that pre-treated CBA can effectively replace a portion of PC in concrete when combined with an appropriate pozzolanic material.This substitution reduces environmental pollution and promotes the sustainability of concrete production.展开更多
We study CO_(2) injection into a saline aquifer intersected by a tectonic fault using a coupled modeling approach to evaluate potential geomechanical risks.The simulation approach integrates the reservoir and mechanic...We study CO_(2) injection into a saline aquifer intersected by a tectonic fault using a coupled modeling approach to evaluate potential geomechanical risks.The simulation approach integrates the reservoir and mechanical simulators through a data transfer algorithm.MUFITS simulates non-isothermal multiphase flow in the reservoir,while FLAC3D calculates its mechanical equilibrium state.We accurately describe the tectonic fault,which consists of damage and core zones,and derive novel analytical closure relations governing the permeability alteration in the fault zone.We estimate the permeability of the activated fracture network in the damage zone and calculate the permeability of the main crack in the fault core,which opens on asperities due to slip.The coupled model is applied to simulate CO_(2) injection into synthetic and realistic reservoirs.In the synthetic reservoir model,we examine the impact of formation depth and initial tectonic stresses on geomechanical risks.Pronounced tectonic stresses lead to inelastic deformations in the fault zone.Regardless of the magnitude of tectonic stress,slip along the fault plane occurs,and the main crack in the fault core opens on asperities,causing CO_(2) leakage out of the storage aquifer.In the realistic reservoir model,we demonstrate that sufficiently high bottomhole pressure induces plastic deformations in the near-wellbore zone,interpreted as rock fracturing,without slippage along the fault plane.We perform a sensitivity analysis of the coupled model,varying the mechanical and flow properties of the storage layers and fault zone to assess fault stability and associated geomechanical risks.展开更多
The objective of this paper is to propose a hybrid approach for the source apportionment of primary and secondary species of PM2.5 in the city of Tangshan. The receptor-based PMF （Positive Matrix Factorization） is i...The objective of this paper is to propose a hybrid approach for the source apportionment of primary and secondary species of PM2.5 in the city of Tangshan. The receptor-based PMF （Positive Matrix Factorization） is integrated with the emission inventory （El） to form the first hybrid method for the source apportionment of the primary species. The hybrid CAMx-PSAT-CP （Comprehensive Air Quality Model with Extensions - Particulate Source App.ortionment Technology - Chemical Profile）approach is then proposed and used for the source apportionment of the secondary species. The PM2.5 sources identified for Tangshan included the soil dust, the metallurgical industry, power plants, coal- fired boilers, vehicles, cement production, and other sources. It is indicated that the PM2.5 pollution is a regional issue. Among all the identified sources, the metallurgy industry was the biggest contribution source.to PM2.5, followed by coal-fired boilers, vehicles and soil dust. The other-source category plays a crucial role for PM2.5, particularly for the formation of secondary species and aerosols, and these other sources include non-specified sources such as agricultural activities, biomass combustion, residential emissions, etc. The source apportionment results could help the local authorities make sound policies and regulations to better protect the citizens from the local and regional PM2.5 pollution. The study also highlights the strength of utilizing the proposed hybrid approaches in the identification of PM2.5 sources. The techniques used in this study show considerable promise for further application to other regions as well as to identify other source categories of PM2.5.展开更多
A method for analyzing reflection and transmission of ocean waves from a semi-infinlte elastic plate with a draft is developed. The relation of energy conservation for plates with three different edge conditions （ fr...A method for analyzing reflection and transmission of ocean waves from a semi-infinlte elastic plate with a draft is developed. The relation of energy conservation for plates with three different edge conditions （ free, simply supported and built-in） is also derived. It is found that the present method satisfies the energy relation very well. The effects of draft on wave reflection and transmission coefficients as well as on the vertical vibration of the plates are examined through numerical tests. It is demonstrated that the zero draft assumption works well for low wave frequencies, but the effect of plate draft becomes significant for high wave frequencies.展开更多
This study develops a flexible latent class model(LCM)to investigate the electric vehicle(EV)type choice decisions of Halifax residents.It utilizes cross-sectional data from the 2022 Halifax Travel Activity(HaliTRAC)s...This study develops a flexible latent class model(LCM)to investigate the electric vehicle(EV)type choice decisions of Halifax residents.It utilizes cross-sectional data from the 2022 Halifax Travel Activity(HaliTRAC)survey,which includes questions related to EV adoption.This study also analyzes eight attitudes and lifestyle preferences related state-ments using the principal component analysis(PCA)technique,and finally extracts three components labeled as“EV enthusiasts”,“sustainable travellers”,and“remote work arrangement admirers”.This paper explores the heterogeneity between two classes for dif-ferent alternative vehicle type choices,e.g.,battery electric vehicle(BEV),plug-in hybrid electric vehicle(PHEV),hybrid electric vehicle(HEV),and regular internal combustion engine(ICE)vehicle.Based on class membership attributes,class-1 can be identified as those who live in suburban areas,have a large family with high vehicle ownership,and are interested in travelling with their family members,especially with their children and vice-versa for class-2.Results suggest that variables across two classes portray heterogene-ity,e.g.,full-time worker portray positive correlation for class-1 and negative to class-2;high annual household income group(more than$200000)exhibit high propensity to choose BEV in class-2 and vice-versa for class-1.Sustainable travelers emphasize the adverse connection towards regular vehicles,while EV enthusiasts demonstrate a favorable association with embracing any type of EV(e.g.,BEV,PHEV,or HEV).Furthermore,the find-ings from this analysis provide guidance for policy measures such as offering purchase incentives,expanding charging infrastructure,and implementing tax rebates to promote the uptake of EVs among the residents of Halifax.展开更多
基金supported by the National Basic Re-search and Development(973)Program of China(No.2005CB724205)The authors appreciate the scientific writing proof offered by Dr.Zou Rui(Tetra Tech Inc,USA)
文摘This article presents the application of an integrated method that estimates the dispersion of polycyclic aromatic hydrocarbons(PAHs)in air,and assesses the human health risk associated with PAHs inhalation.An uncertainty analysis method consisting of three components were applied in this study,where the three components include a bootstrapping method for analyzing the whole process associated uncertainty,an inhalation rate(IR)representation for evaluating the total PAH inhalation risk for human health,and a normally distributed absorption fraction(AF)ranging from 0%to 100%to represent the absorption capability of PAHs in human body.Using this method,an integrated process was employed to assess the health risk of the residents in Beijing,China,from inhaling PAHs in the air.The results indicate that the ambient air PAHs in Beijing is an important contributor to human health impairment,although over 68%of residents seem to be safe from daily PAH carcinogenic inhalation.In general,the accumulated daily inhalation amount is relatively higher for male and children at 10 years old of age than for female and children at 6 years old.In 1997,about 1.73%cancer sufferers in Beijing were more or less related to ambient air PAHs inhalation.At 95%confidence interval,approximately 272-309 individual cancer incidences can be attributed to PAHs pollution in the air.The probability of greater than 500 cancer occurrence is 15.3%.While the inhalation of ambient air PAHs was shown to be an important factor responsible for higher cancer occurrence in Beijing,while the contribution might not be the most significant one.
文摘Current practice of underground artificial ground freezing(AGF)typically involves huge refrigeration systems of large economic and environmental costs.In this study,a novel AGF technique is proposed deploying available cold wind in cold regions.This is achieved by a static heat transfer device called thermosyphon equipped with an air insulation layer.A refrigeration unit can be optionally integrated to meet additional cooling requirements.The introduction of air insulation isolates the thermosyphon from ground zones where freezing is not needed,resulting in:(1)steering the cooling resources(cold wind or refrigeration)towards zones of interest;and(2)minimizing refrigeration load.This design is demonstrated using well-validated mathematical models from our previous work based on two-phase enthalpy method of the ground coupled with a thermal resistance network for the thermosyphon.Two Canadian mines are considered:the Cigar Lake Mine and the Giant Mine.The results show that our proposed design can speed the freezing time by 30%at the Giant Mine and by two months at the Cigar Lake Mine.Further,a cooling load of 2.4 GWh can be saved at the Cigar Lake Mine.Overall,this study provides mining practitioners with sustainable solutions of underground AGF.
基金This research was supported by the Natural Sciences and Engineering Research Council of Canada,MIRARCO Mining Innovation,the Center for Excellence in Mining Innovation(CEMI),and Itasca Consulting Group.The authors wish to thank Dr.Evert Hoek for sharing his notes on the historical development of the HB failure criterion including laboratory test data on Panguna andesite and acknowledge his many constructive comments and suggestions during the conduct of the research reported here.
文摘The strength of jointed rock mass is strongly controlled by the degree of interlock between its constituent rock blocks.The degree of interlock constrains the kinematic freedom of individual rock blocks to rotate and slide along the block forming joints.The HoekeBrown(HB)failure criterion and the geological strength index(GSI)were developed based on experiences from mine slopes and tunneling projects in moderately to poorly interlocked jointed rock masses.It has since then been demonstrated that the approach to estimate the HB strength parameters based on the GSI strength scaling equations(called the‘GSI strength equations’)tends to underestimate the confined peak strength of highly interlocked jointed rock masses(i.e.GSI>65),where the rock mass is often non-persistently jointed,and the intact rock blocks are strong and brittle.The estimation of the confined strength of such rock masses is relevant when designing mine pillars and abutments at great depths,where the confining pressure is high enough to prevent block rotation and free sliding on block boundaries.In this article,a grain-based distinct element modeling approach is used to simulate jointed rock masses of various degrees of interlock and to investigate the influences of block shape,joint persistence and joint surface condition on the confined peak strengths.The focus is on non-persistently jointed and blocky(persistently jointed)rock masses,consisting of hard and homogeneous rock blocks devoid of any strength degrading defects such as veins.The results from this investigation confirm that the GSI strength equations underestimate the confined strength of highly interlocked and non-persistently jointed rock masses.Moreover,the GSI strength equations are found to be valid to estimate the confined strength of persistently jointed rock masses with smooth and non-dilatant joint surfaces.
文摘The COVID-19 pandemic has significantly affected global transportation mobility,presenting unprecedented challenges to transportation management.Public transit and ride-hailing services saw a drastic reduction in ridership,leading to an increased inclination towards private vehicles.The pandemic also altered travel patterns and individual mobility due to various COVID-19 protocols.This study conducted a comprehensive review of 96 academic papers spanning from January 1,2020,to December 31,2022,focusing on transportation and mobility using the Scopus database.Three major themes were identified:‘Impact on Ride-Hailing Services',‘Impact on Mode Preference',and‘Impact on Trip Purpose',with subdivisions based on keywords and key findings extracted using VOSviewer.The pandemic significantly impacted ride-hailing services,altering demand,usage,and safety measures.Mode preference shifted towards private vehicles due to safety concerns.The present study underscores the long-term implications of the pandemic,emphasizing recovery strategies for ride-hailing services and mode preferences post-pandemic.It highlights the need for sustainable transportation policies,advocating for enhanced public transportation systems,promoting active travel modes,and addressing socioeconomic disparities in mobility patterns.The findings emphasize the need for resilient transportation strategies in the face of future disruptions.
文摘Concrete comprises aggregates of various sizes bound by a cementitious paste,with Portland cement(PC)as the primary binder since the 19th century.However,PC production depletes non-renewable natural resources and causes environmental degradation.Meanwhile,approximately 130 billion kilograms of cattle bones(CB)are generated globally each year,posing environmental challenges due to their non-biodegradability.CB is rich in calcium oxide,making it a potential supplementary material in cement production.This study explores the feasibility of using pretreated cattle bone ash(CBA)as a partial replacement for PC in concrete,combined with 5%silica fume and 10%fly ash.CBA was incorporated at 10%,25%,50%,and 75%by weight of cement.The results indicated that mixes containing 10%and 25%CBA achieved high-strength concrete exceeding 60 MPa after 28 d,while mixes with 50%and 75%CBA produced structural-grade concrete with strengths above 25 MPa.The findings demonstrate that pre-treated CBA can effectively replace a portion of PC in concrete when combined with an appropriate pozzolanic material.This substitution reduces environmental pollution and promotes the sustainability of concrete production.
文摘We study CO_(2) injection into a saline aquifer intersected by a tectonic fault using a coupled modeling approach to evaluate potential geomechanical risks.The simulation approach integrates the reservoir and mechanical simulators through a data transfer algorithm.MUFITS simulates non-isothermal multiphase flow in the reservoir,while FLAC3D calculates its mechanical equilibrium state.We accurately describe the tectonic fault,which consists of damage and core zones,and derive novel analytical closure relations governing the permeability alteration in the fault zone.We estimate the permeability of the activated fracture network in the damage zone and calculate the permeability of the main crack in the fault core,which opens on asperities due to slip.The coupled model is applied to simulate CO_(2) injection into synthetic and realistic reservoirs.In the synthetic reservoir model,we examine the impact of formation depth and initial tectonic stresses on geomechanical risks.Pronounced tectonic stresses lead to inelastic deformations in the fault zone.Regardless of the magnitude of tectonic stress,slip along the fault plane occurs,and the main crack in the fault core opens on asperities,causing CO_(2) leakage out of the storage aquifer.In the realistic reservoir model,we demonstrate that sufficiently high bottomhole pressure induces plastic deformations in the near-wellbore zone,interpreted as rock fracturing,without slippage along the fault plane.We perform a sensitivity analysis of the coupled model,varying the mechanical and flow properties of the storage layers and fault zone to assess fault stability and associated geomechanical risks.
文摘The objective of this paper is to propose a hybrid approach for the source apportionment of primary and secondary species of PM2.5 in the city of Tangshan. The receptor-based PMF （Positive Matrix Factorization） is integrated with the emission inventory （El） to form the first hybrid method for the source apportionment of the primary species. The hybrid CAMx-PSAT-CP （Comprehensive Air Quality Model with Extensions - Particulate Source App.ortionment Technology - Chemical Profile）approach is then proposed and used for the source apportionment of the secondary species. The PM2.5 sources identified for Tangshan included the soil dust, the metallurgical industry, power plants, coal- fired boilers, vehicles, cement production, and other sources. It is indicated that the PM2.5 pollution is a regional issue. Among all the identified sources, the metallurgy industry was the biggest contribution source.to PM2.5, followed by coal-fired boilers, vehicles and soil dust. The other-source category plays a crucial role for PM2.5, particularly for the formation of secondary species and aerosols, and these other sources include non-specified sources such as agricultural activities, biomass combustion, residential emissions, etc. The source apportionment results could help the local authorities make sound policies and regulations to better protect the citizens from the local and regional PM2.5 pollution. The study also highlights the strength of utilizing the proposed hybrid approaches in the identification of PM2.5 sources. The techniques used in this study show considerable promise for further application to other regions as well as to identify other source categories of PM2.5.
基金The present work was financially supported by the National Natural Science Foundation of China under contract No.50428908the Program for Changjiang Scholars and Innovative Research Team in University of China under contract No.IRT0420.
文摘A method for analyzing reflection and transmission of ocean waves from a semi-infinlte elastic plate with a draft is developed. The relation of energy conservation for plates with three different edge conditions （ free, simply supported and built-in） is also derived. It is found that the present method satisfies the energy relation very well. The effects of draft on wave reflection and transmission coefficients as well as on the vertical vibration of the plates are examined through numerical tests. It is demonstrated that the zero draft assumption works well for low wave frequencies, but the effect of plate draft becomes significant for high wave frequencies.
文摘This study develops a flexible latent class model(LCM)to investigate the electric vehicle(EV)type choice decisions of Halifax residents.It utilizes cross-sectional data from the 2022 Halifax Travel Activity(HaliTRAC)survey,which includes questions related to EV adoption.This study also analyzes eight attitudes and lifestyle preferences related state-ments using the principal component analysis(PCA)technique,and finally extracts three components labeled as“EV enthusiasts”,“sustainable travellers”,and“remote work arrangement admirers”.This paper explores the heterogeneity between two classes for dif-ferent alternative vehicle type choices,e.g.,battery electric vehicle(BEV),plug-in hybrid electric vehicle(PHEV),hybrid electric vehicle(HEV),and regular internal combustion engine(ICE)vehicle.Based on class membership attributes,class-1 can be identified as those who live in suburban areas,have a large family with high vehicle ownership,and are interested in travelling with their family members,especially with their children and vice-versa for class-2.Results suggest that variables across two classes portray heterogene-ity,e.g.,full-time worker portray positive correlation for class-1 and negative to class-2;high annual household income group(more than$200000)exhibit high propensity to choose BEV in class-2 and vice-versa for class-1.Sustainable travelers emphasize the adverse connection towards regular vehicles,while EV enthusiasts demonstrate a favorable association with embracing any type of EV(e.g.,BEV,PHEV,or HEV).Furthermore,the find-ings from this analysis provide guidance for policy measures such as offering purchase incentives,expanding charging infrastructure,and implementing tax rebates to promote the uptake of EVs among the residents of Halifax.
