Internal erosion occurs when fine particles escape from the soil driven by seepage flow,which is considered to be the crucial factor causing the failure of earth structures filled with gravelly soil.The objective of t...Internal erosion occurs when fine particles escape from the soil driven by seepage flow,which is considered to be the crucial factor causing the failure of earth structures filled with gravelly soil.The objective of this paper is to suggest an appropriate method to assess internal erosion potential of gravelly soil.By analyzing the sensitivity of soil material to internal erosion,the variable(Dc15/df85)max and the content of coarse particles(Pc)are selected as the evaluation indexes(Dc15 and df85 are the diameters of 15%mass passing in the coarse component and 85%mass passing in the fine component,respectively).A series of gravelly soils with different particle size distributions are tested for internal erosion by the self-made permeameter.Based on the test results,an evaluation method for the internal erosion of gravelly soil is proposed.Gravelly soil is prone to internal erosion when 60%≤Pc<95%and(Dc15/df85)max≥9.5.The proposed method shows good accuracy in evaluating the internal erosion of 36 soil samples from other studies,which confirms the reliability of the method.The proposed method makes it possible to accurately assess internal erosion of gravelly soil,and an alternative method is provided for engineers to determine whether there is a risk of internal erosion in earth structures consisting of gravelly soil.展开更多
This paper attempts to evaluate New Horizon College English(Reading and Writing,Book I, Second Edition) based on the textbook evaluation criteria by Hutchinson& Waters. The analyses proves that that it is fit for ...This paper attempts to evaluate New Horizon College English(Reading and Writing,Book I, Second Edition) based on the textbook evaluation criteria by Hutchinson& Waters. The analyses proves that that it is fit for college students under the circumstances of so many newly published English teaching materials claimed to be excellent and helpful.However, teachers should be aware to take good advantage of the textbook and supplement the students with some necessary resources during teaching due to its limitations.展开更多
Shale gas is being hailed as the green energy of the future due to high heating value,low carbon emissions,and large reserves.Gas content of shale is a key parameter for evaluating the shale gas potential and screenin...Shale gas is being hailed as the green energy of the future due to high heating value,low carbon emissions,and large reserves.Gas content of shale is a key parameter for evaluating the shale gas potential and screening for the shale gas sweet spots.Although the concept of gas content has been well defined,obtaining a reliable gas content data still remains a challenge.A significant barrier is the method for evaluating the gas content.In this paper,we provide a review of the long-established and recently developed gas content evaluation methods.In the first part of this review article,the history of gas content evaluation methods is summarized since 1910s,relied on published and unpublished literatures as well as our own experiences.Then,the fundamental contents and concepts involved in gas content evaluation are introduced to provide a clear theoretical foundation for the methods.In the third part,eleven evaluation methods,including four direct methods and seven indirect methods,are systematically reviewed.In each method,its application to evaluating the gas content is presented,the key advances are highlighted,and the advantages and limitations are discussed.Finally,future directions are discussed to promote creative thinking across disciplines to develop new methods or improve current methods for evaluating the gas content more accurately and efficiently.展开更多
In order to obtain effective parameters for complex sand reservoirs,a log evaluation method for relevant reservoir parameters is established based on an analysis in the gas-bearing sandstone with high porosity and low...In order to obtain effective parameters for complex sand reservoirs,a log evaluation method for relevant reservoir parameters is established based on an analysis in the gas-bearing sandstone with high porosity and low permeability,low porosity and permeability and on various characteristics of log responses to reservoir lithologies and physical properties in the Neopleozoic sand reservoir of the Ordos basin.This log evaluation method covers the Cook method that is used to evaluate the porosity and oiliness in high porosity and low permeability reservoirs and another method in which the mineral content,derived from geochemical logs,is used to identify formation lithologies.Some areas have high calcium and low silt content,not uniformly distributed,the results of which show up in the complex formation lithologies and conventional log responses with great deviation.The reliability of the method is verified by comparison with conventional log data and core analyses.The calculation results coincide with the core analytical data and gas tests,which indicate that this log evaluation method is available,provides novel ideas for study of similar complex reservoir lithologies and has some reference value.展开更多
Based on the empirical investigation of presentation in college English classes for junior non-English majors in science and engineering universities,the author explains her own thinking on how to improve presentation...Based on the empirical investigation of presentation in college English classes for junior non-English majors in science and engineering universities,the author explains her own thinking on how to improve presentation teaching from four aspects:setting teaching objectives,selecting teaching contents,using teaching methods,and evaluating and implementing methods.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.41790432)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA20030301)。
文摘Internal erosion occurs when fine particles escape from the soil driven by seepage flow,which is considered to be the crucial factor causing the failure of earth structures filled with gravelly soil.The objective of this paper is to suggest an appropriate method to assess internal erosion potential of gravelly soil.By analyzing the sensitivity of soil material to internal erosion,the variable(Dc15/df85)max and the content of coarse particles(Pc)are selected as the evaluation indexes(Dc15 and df85 are the diameters of 15%mass passing in the coarse component and 85%mass passing in the fine component,respectively).A series of gravelly soils with different particle size distributions are tested for internal erosion by the self-made permeameter.Based on the test results,an evaluation method for the internal erosion of gravelly soil is proposed.Gravelly soil is prone to internal erosion when 60%≤Pc<95%and(Dc15/df85)max≥9.5.The proposed method shows good accuracy in evaluating the internal erosion of 36 soil samples from other studies,which confirms the reliability of the method.The proposed method makes it possible to accurately assess internal erosion of gravelly soil,and an alternative method is provided for engineers to determine whether there is a risk of internal erosion in earth structures consisting of gravelly soil.
文摘This paper attempts to evaluate New Horizon College English(Reading and Writing,Book I, Second Edition) based on the textbook evaluation criteria by Hutchinson& Waters. The analyses proves that that it is fit for college students under the circumstances of so many newly published English teaching materials claimed to be excellent and helpful.However, teachers should be aware to take good advantage of the textbook and supplement the students with some necessary resources during teaching due to its limitations.
基金supported by the National Natural Science Foundation of China(42202175,41927801,and 42102128)the Open Foundation of State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development(33550000-22-ZC0613-0296)。
文摘Shale gas is being hailed as the green energy of the future due to high heating value,low carbon emissions,and large reserves.Gas content of shale is a key parameter for evaluating the shale gas potential and screening for the shale gas sweet spots.Although the concept of gas content has been well defined,obtaining a reliable gas content data still remains a challenge.A significant barrier is the method for evaluating the gas content.In this paper,we provide a review of the long-established and recently developed gas content evaluation methods.In the first part of this review article,the history of gas content evaluation methods is summarized since 1910s,relied on published and unpublished literatures as well as our own experiences.Then,the fundamental contents and concepts involved in gas content evaluation are introduced to provide a clear theoretical foundation for the methods.In the third part,eleven evaluation methods,including four direct methods and seven indirect methods,are systematically reviewed.In each method,its application to evaluating the gas content is presented,the key advances are highlighted,and the advantages and limitations are discussed.Finally,future directions are discussed to promote creative thinking across disciplines to develop new methods or improve current methods for evaluating the gas content more accurately and efficiently.
基金supported by the Program for New Century Excellent Talents in Universities
文摘In order to obtain effective parameters for complex sand reservoirs,a log evaluation method for relevant reservoir parameters is established based on an analysis in the gas-bearing sandstone with high porosity and low permeability,low porosity and permeability and on various characteristics of log responses to reservoir lithologies and physical properties in the Neopleozoic sand reservoir of the Ordos basin.This log evaluation method covers the Cook method that is used to evaluate the porosity and oiliness in high porosity and low permeability reservoirs and another method in which the mineral content,derived from geochemical logs,is used to identify formation lithologies.Some areas have high calcium and low silt content,not uniformly distributed,the results of which show up in the complex formation lithologies and conventional log responses with great deviation.The reliability of the method is verified by comparison with conventional log data and core analyses.The calculation results coincide with the core analytical data and gas tests,which indicate that this log evaluation method is available,provides novel ideas for study of similar complex reservoir lithologies and has some reference value.
文摘Based on the empirical investigation of presentation in college English classes for junior non-English majors in science and engineering universities,the author explains her own thinking on how to improve presentation teaching from four aspects:setting teaching objectives,selecting teaching contents,using teaching methods,and evaluating and implementing methods.
