Microplastics(MPs)are important exempla of the Anthropocene and are exerting an increasing impact on Earth’s carbon cycle.The huge imbalance between the MPs floating on the marine surface and those that are estimated...Microplastics(MPs)are important exempla of the Anthropocene and are exerting an increasing impact on Earth’s carbon cycle.The huge imbalance between the MPs floating on the marine surface and those that are estimated to have been introduced into the ocean necessitates a detailed assessment of marine MP sinks.Here,we demonstrate that cold seep sediments,which are characterized by methane fluid seepage and a chemosynthetic ecosystem,effectively capture and accommodate small-scale(<100μm)MPs,with 16 types of MPs being detected.The abundance of MPs in the surface of the sediment is higher in methane-seepage locations than in non-seepage areas.Methane seepage is beneficial to the accumulation,fragmentation,increased diversity,and aging of MPs.In turn,the rough surfaces of MPs contribute to the sequestration of the electron acceptor ferric oxide,which is associated with the anaerobic oxidation of methane(AOM).The efficiency of the AOM determines whether the seeping methane(which has a greenhouse effect 83 times greater than that of CO_(2)over a 20-year period)can enter the atmosphere,which is important to the global methane cycle,since the deep-sea environment is regarded as the largest methane reservoir associated with natural gas hydrates.展开更多
Identification of security risk factors for small reservoirs is the basis for implementation of early warning systems.The manner of identification of the factors for small reservoirs is of practical significance when ...Identification of security risk factors for small reservoirs is the basis for implementation of early warning systems.The manner of identification of the factors for small reservoirs is of practical significance when data are incomplete.The existing grey relational models have some disadvantages in measuring the correlation between categorical data sequences.To this end,this paper introduces a new grey relational model to analyze heterogeneous data.In this study,a set of security risk factors for small reservoirs was first constructed based on theoretical analysis,and heterogeneous data of these factors were recorded as sequences.The sequences were regarded as random variables,and the information entropy and conditional entropy between sequences were measured to analyze the relational degree between risk factors.Then,a new grey relational analysis model for heterogeneous data was constructed,and a comprehensive security risk factor identification method was developed.A case study of small reservoirs in Guangxi Zhuang Autonomous Region in China shows that the model constructed in this study is applicable to security risk factor identification for small reservoirs with heterogeneous and sparse data.展开更多
According to the multi-project and program management theory, this paper analyzes the program generation principle and establishes a program based on progress goals. On the basis of the present situation of calculatio...According to the multi-project and program management theory, this paper analyzes the program generation principle and establishes a program based on progress goals. On the basis of the present situation of calculation of penalty for delay of the bidding section construction period with the critical path method, we studied the effects of contractor-induced delay of the bidding section construction period in detail, including the effects on the construction period of the bidding section itself, the earliest start times of the next bidding section and other subsequent bidding sections, and the construction period of the program, and then constructed a penalty model for delay of the bidding section construction period from the perspective of programs. Using the penalty model, we conducted a practical analysis of penalty for delay of the construction period of the Baoying station program in the South-to-North Water Diversion Project. The model can help determine the amount of penalty for delay of the construction period in bidding sections scientifically and reasonably.展开更多
Recently,the critical chain study has become a hot issue in the project management research field.The construction of the critical chain with multi-resource constraints is a new research subject.According to the syste...Recently,the critical chain study has become a hot issue in the project management research field.The construction of the critical chain with multi-resource constraints is a new research subject.According to the system analysis theory and project portfolio theory,this paper discusses the creation of project portfolios based on the similarity principle and gives the definition of priority in multi-resource allocation based on quantitative analysis.A model with multi-resource constraints,which can be applied to the critical chain construction of the A-bid section in the South-to-North Water Diversion Project,was proposed.Contrast analysis with the comprehensive treatment construction method and aggressive treatment construction method was carried out.This paper also makes suggestions for further research directions and subjects,which will be useful in improving the theories in relevant research fields.展开更多
During the past decades,public attention regarding global warming has mainly focused on CO_(2) reduction;however,CH4,another important greenhouse gas,has a global warming potential that is 84 times higher than that of...During the past decades,public attention regarding global warming has mainly focused on CO_(2) reduction;however,CH4,another important greenhouse gas,has a global warming potential that is 84 times higher than that of CO_(2) on a 20-year basis.The annual atmospheric amount of CH4 in 2020 reached its highest level since systematic monitoring began in 1983(Figure 1A).To date,despite coronavirus 2019 shutdowns,methane has contributed approximately 30%to global warming.Recently,a series of timely appeals,such as“The Global Methane Pledge”signed at the United Nations Climate Change Conference(COP26)and the“Global Methane Assessment”from the United Nations Environment Program,have called on global methane reduction and mitigation.展开更多
基金financially supported by the National Natural Science Foundation of China(42022046)the National Key Research and Development Program of China(2021YFF0502300)+1 种基金the Key Special Project for Introduced Talent Teams of the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0403 and GML2019ZD0401)Guangdong Natural Resources Foundation(GDNRC[2022]45)。
文摘Microplastics(MPs)are important exempla of the Anthropocene and are exerting an increasing impact on Earth’s carbon cycle.The huge imbalance between the MPs floating on the marine surface and those that are estimated to have been introduced into the ocean necessitates a detailed assessment of marine MP sinks.Here,we demonstrate that cold seep sediments,which are characterized by methane fluid seepage and a chemosynthetic ecosystem,effectively capture and accommodate small-scale(<100μm)MPs,with 16 types of MPs being detected.The abundance of MPs in the surface of the sediment is higher in methane-seepage locations than in non-seepage areas.Methane seepage is beneficial to the accumulation,fragmentation,increased diversity,and aging of MPs.In turn,the rough surfaces of MPs contribute to the sequestration of the electron acceptor ferric oxide,which is associated with the anaerobic oxidation of methane(AOM).The efficiency of the AOM determines whether the seeping methane(which has a greenhouse effect 83 times greater than that of CO_(2)over a 20-year period)can enter the atmosphere,which is important to the global methane cycle,since the deep-sea environment is regarded as the largest methane reservoir associated with natural gas hydrates.
基金supported by the National Nature Science Foundation of China(Grant No.71401052)the National Social Science Foundation of China(Grant No.17BGL156)the Key Project of the National Social Science Foundation of China(Grant No.14AZD024)
文摘Identification of security risk factors for small reservoirs is the basis for implementation of early warning systems.The manner of identification of the factors for small reservoirs is of practical significance when data are incomplete.The existing grey relational models have some disadvantages in measuring the correlation between categorical data sequences.To this end,this paper introduces a new grey relational model to analyze heterogeneous data.In this study,a set of security risk factors for small reservoirs was first constructed based on theoretical analysis,and heterogeneous data of these factors were recorded as sequences.The sequences were regarded as random variables,and the information entropy and conditional entropy between sequences were measured to analyze the relational degree between risk factors.Then,a new grey relational analysis model for heterogeneous data was constructed,and a comprehensive security risk factor identification method was developed.A case study of small reservoirs in Guangxi Zhuang Autonomous Region in China shows that the model constructed in this study is applicable to security risk factor identification for small reservoirs with heterogeneous and sparse data.
基金supported by the National Science and Technology Plan of China (Major Project of the Eleventh Five-Year Plan, Grant No. 2006BAB04A13)the Philosophy and Social Science Fund of Education Department of Jiangsu Province (Grant No. 07SJD630006)+1 种基金the Third Key Discipline (Techno-Economics and Management) of the Project 211the Key Disciplines of Jiangsu Province (Engineering and Project Management)
文摘According to the multi-project and program management theory, this paper analyzes the program generation principle and establishes a program based on progress goals. On the basis of the present situation of calculation of penalty for delay of the bidding section construction period with the critical path method, we studied the effects of contractor-induced delay of the bidding section construction period in detail, including the effects on the construction period of the bidding section itself, the earliest start times of the next bidding section and other subsequent bidding sections, and the construction period of the program, and then constructed a penalty model for delay of the bidding section construction period from the perspective of programs. Using the penalty model, we conducted a practical analysis of penalty for delay of the construction period of the Baoying station program in the South-to-North Water Diversion Project. The model can help determine the amount of penalty for delay of the construction period in bidding sections scientifically and reasonably.
基金supported by the National Science and Technology Plan (Major Project of the Eleventh Five-Year Plan,Grant No. 2006BAB04A13)the Philosophy and Social Science Fund of the Education Department of Jiangsu Province (Grant No.07SJD630006)+2 种基金the Third Key Discipline (Techno-Economics and Management) of the 211 Projectthe Key Discipline of Jiangsu Province (Engineering and Project Management)the Office of the South-to-North Water Diversion Project Construction Committee under the State Council
文摘Recently,the critical chain study has become a hot issue in the project management research field.The construction of the critical chain with multi-resource constraints is a new research subject.According to the system analysis theory and project portfolio theory,this paper discusses the creation of project portfolios based on the similarity principle and gives the definition of priority in multi-resource allocation based on quantitative analysis.A model with multi-resource constraints,which can be applied to the critical chain construction of the A-bid section in the South-to-North Water Diversion Project,was proposed.Contrast analysis with the comprehensive treatment construction method and aggressive treatment construction method was carried out.This paper also makes suggestions for further research directions and subjects,which will be useful in improving the theories in relevant research fields.
基金supported by the National Natural Science Foundation of China(42022046)the National Key Research and Development Program(2021YFF0502300)+1 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(GML2019ZD0401 and GML2019ZD0403)Guangdong Natural Resources Foundation(GDNRC[2022]45)。
基金support for this research received from the National Natural Science Foundation of China(42022046 and 52122602)the National Key Research and Development Program(2021YFF0502300)Guangdong Natural Resources Foundation(GDNRC[2022]45)。
文摘During the past decades,public attention regarding global warming has mainly focused on CO_(2) reduction;however,CH4,another important greenhouse gas,has a global warming potential that is 84 times higher than that of CO_(2) on a 20-year basis.The annual atmospheric amount of CH4 in 2020 reached its highest level since systematic monitoring began in 1983(Figure 1A).To date,despite coronavirus 2019 shutdowns,methane has contributed approximately 30%to global warming.Recently,a series of timely appeals,such as“The Global Methane Pledge”signed at the United Nations Climate Change Conference(COP26)and the“Global Methane Assessment”from the United Nations Environment Program,have called on global methane reduction and mitigation.
