Polychlorinated naphthalenes(PCNs)are detrimental to human health and the environment.With the commercial production of PCNs banned,unintentional releases have emerged as a significant environmental source.However,rel...Polychlorinated naphthalenes(PCNs)are detrimental to human health and the environment.With the commercial production of PCNs banned,unintentional releases have emerged as a significant environmental source.However,relevant information is still scarce.In this study,provincial emissions for eight PCNs homologues from 37 sources in the Chinese mainland during the period of 1960-2019 were estimated based on a source-specific and time-varying emission factor database.The results showed that the total PCNs emissions in 2019 reached 757.0 kg with Hebei ranked at the top among all the provinces and iron&steel industry as the biggest source.Low-chlorinated PCNs comprised 90%of emissions by mass,while highly chlorinated PCNs dominated in terms of toxicity,highlighting divergent priorities for mitigating emissions and safeguarding human health.The emissions showed an overall upward trend from 1960 to 2019 driven by emission increase from iron&steel industry in terms of source,and from North China and East China in terms of geographic area.Per-capita emissions followed an inverted U-shaped environmental Kuznets curvewhile emission intensities decreased with increasing per-capita Gross Domestic Product(GDP)following a nearly linear pattern when log-transformed.展开更多
Atmospheric Oxygen(O2)is one of the dominating features that allow the earth to be a habitable planet with advanced civilization and diverse biology.However,since the late 1980 s,observational data have indicated a st...Atmospheric Oxygen(O2)is one of the dominating features that allow the earth to be a habitable planet with advanced civilization and diverse biology.However,since the late 1980 s,observational data have indicated a steady decline in O2 content on the scale of parts-per-million level.The current scientific consensus is that the decline is caused by the fossil-fuel combustion;however,few works have been done to quantitatively evaluate the response of O2 cycle under the anthropogenic impact,at both the global and regional scales.This paper manages to quantify the land O2 flux and makes the initial step to quantificationally describe the anthropogenic impacts on the global O2 budget.Our estimation reveals that the global O2 consumption has experienced an increase from 33.69±1.11 to47.63±0.80 Gt(gigaton,109 t)O2yr^-1 between 2000 and 2018,while the land production of O2(totaling 11.34±13.48 Gt O2yr^-1 averaged over the same period)increased only slightly.In 2018,the combustion of fossil-fuel and industrial activities(38.45±0.61 Gt O2yr^-1)contributed the most to consumption,followed by wildfires(4.97±0.48 Gt O2yr^-1)as well as livestock and human respiration processes(2.48±0.16 and 1.73±0.13 Gt O2yr^-1,respectively).Burning of fossil-fuel that causes large O2 fluxes occurs in East Asia,India,North America,and Europe,while wildfires that cause large fluxes in comparable magnitude are mainly distributed in central Africa.展开更多
Screw conveyors,widely used devices for transporting bulk materials,play an irreplaceable role in the modern industrial system.Despite of their traditional advantages,designers of screw conveyors still heavily rely on...Screw conveyors,widely used devices for transporting bulk materials,play an irreplaceable role in the modern industrial system.Despite of their traditional advantages,designers of screw conveyors still heavily rely on their own country's experiments and standards,which are closely related to empirical data.Therefore,the same conveying task often results in different designs.This work aims to compare the design standards of screw conveyors in China,Germany and the USA.Based on related standards acquired from renowned associations in the three countries,the similarities and particularities of these design guidances are compared.With preforming the geometrical and operational designs for horizon-tal,slightly inclined and vertical conveyance of three representative bulk solids(barley,lignite,sand),the advantages and disadvantages of these semi-empirical designs are comprehensively presented.Fur-thermore,the potential influence of empirical coefficients,which are not explicitly documented,are extensively discussed.By analysing all outcomes,the compatibility and applicability of each standard are qualitatively assessed.展开更多
This part of the study aims to evaluate the advantages and disadvantages of technical standards of screw conveyors in China,Germany,and the USA for industrial applications.The source or determination method of empiric...This part of the study aims to evaluate the advantages and disadvantages of technical standards of screw conveyors in China,Germany,and the USA for industrial applications.The source or determination method of empirical coefficients as well as the theoretical foundation of dimensioning-relevant diagrams in these standards is not explicitly documented in the literature.Therefore,instead of less efficient on-site tests,the numerical simulation by discrete element method is conducted.Based on the geometrical and operational designs determined in three standards for horizontal,slightly inclined,and vertical conveyance of three representative bulk solids(barley,lignite,and sand),the potential influencing factors are discussed.With constant particle and contact parameters,the potential deviations caused by particle models are eliminated.Furthermore,the accuracy of power consumption calculation of each standard and the divergence between accessible and required mass flows is comprehensively assessed based on the analysis of simulated outcomes.Two main conclusions are drawn:(1)Particle fall back is barely considered by all three standards and leads to overestimated mass throughput;(2)The decrease in mass throughput caused by an increasing degree of filling can be compensated by slowing down the rotational speed.展开更多
基金supported by National Key R&D Program of China (No.2022YFC3105800)the National Natural Science Foundation of China (Nos.42277388,42230505,42206148,and 41907313)the Science and Technology Commission of Shanghai Municipality (No.19ZR1415100).
文摘Polychlorinated naphthalenes(PCNs)are detrimental to human health and the environment.With the commercial production of PCNs banned,unintentional releases have emerged as a significant environmental source.However,relevant information is still scarce.In this study,provincial emissions for eight PCNs homologues from 37 sources in the Chinese mainland during the period of 1960-2019 were estimated based on a source-specific and time-varying emission factor database.The results showed that the total PCNs emissions in 2019 reached 757.0 kg with Hebei ranked at the top among all the provinces and iron&steel industry as the biggest source.Low-chlorinated PCNs comprised 90%of emissions by mass,while highly chlorinated PCNs dominated in terms of toxicity,highlighting divergent priorities for mitigating emissions and safeguarding human health.The emissions showed an overall upward trend from 1960 to 2019 driven by emission increase from iron&steel industry in terms of source,and from North China and East China in terms of geographic area.Per-capita emissions followed an inverted U-shaped environmental Kuznets curvewhile emission intensities decreased with increasing per-capita Gross Domestic Product(GDP)following a nearly linear pattern when log-transformed.
基金Supported by the National Natural Science Foundation of China (41521004)China 111 Project (B13045)
文摘Atmospheric Oxygen(O2)is one of the dominating features that allow the earth to be a habitable planet with advanced civilization and diverse biology.However,since the late 1980 s,observational data have indicated a steady decline in O2 content on the scale of parts-per-million level.The current scientific consensus is that the decline is caused by the fossil-fuel combustion;however,few works have been done to quantitatively evaluate the response of O2 cycle under the anthropogenic impact,at both the global and regional scales.This paper manages to quantify the land O2 flux and makes the initial step to quantificationally describe the anthropogenic impacts on the global O2 budget.Our estimation reveals that the global O2 consumption has experienced an increase from 33.69±1.11 to47.63±0.80 Gt(gigaton,109 t)O2yr^-1 between 2000 and 2018,while the land production of O2(totaling 11.34±13.48 Gt O2yr^-1 averaged over the same period)increased only slightly.In 2018,the combustion of fossil-fuel and industrial activities(38.45±0.61 Gt O2yr^-1)contributed the most to consumption,followed by wildfires(4.97±0.48 Gt O2yr^-1)as well as livestock and human respiration processes(2.48±0.16 and 1.73±0.13 Gt O2yr^-1,respectively).Burning of fossil-fuel that causes large O2 fluxes occurs in East Asia,India,North America,and Europe,while wildfires that cause large fluxes in comparable magnitude are mainly distributed in central Africa.
基金This project has received funding from the European Union's Horizon 2020 Program(H2020/2014-2020),under grant agreement no.654446.
文摘Screw conveyors,widely used devices for transporting bulk materials,play an irreplaceable role in the modern industrial system.Despite of their traditional advantages,designers of screw conveyors still heavily rely on their own country's experiments and standards,which are closely related to empirical data.Therefore,the same conveying task often results in different designs.This work aims to compare the design standards of screw conveyors in China,Germany and the USA.Based on related standards acquired from renowned associations in the three countries,the similarities and particularities of these design guidances are compared.With preforming the geometrical and operational designs for horizon-tal,slightly inclined and vertical conveyance of three representative bulk solids(barley,lignite,sand),the advantages and disadvantages of these semi-empirical designs are comprehensively presented.Fur-thermore,the potential influence of empirical coefficients,which are not explicitly documented,are extensively discussed.By analysing all outcomes,the compatibility and applicability of each standard are qualitatively assessed.
基金the European Union's Horizon 2020 Program(H2020/2014–2020)under grant agreement No.654446.
文摘This part of the study aims to evaluate the advantages and disadvantages of technical standards of screw conveyors in China,Germany,and the USA for industrial applications.The source or determination method of empirical coefficients as well as the theoretical foundation of dimensioning-relevant diagrams in these standards is not explicitly documented in the literature.Therefore,instead of less efficient on-site tests,the numerical simulation by discrete element method is conducted.Based on the geometrical and operational designs determined in three standards for horizontal,slightly inclined,and vertical conveyance of three representative bulk solids(barley,lignite,and sand),the potential influencing factors are discussed.With constant particle and contact parameters,the potential deviations caused by particle models are eliminated.Furthermore,the accuracy of power consumption calculation of each standard and the divergence between accessible and required mass flows is comprehensively assessed based on the analysis of simulated outcomes.Two main conclusions are drawn:(1)Particle fall back is barely considered by all three standards and leads to overestimated mass throughput;(2)The decrease in mass throughput caused by an increasing degree of filling can be compensated by slowing down the rotational speed.
