The natural phenomenon associated with the chemical dissolution of dissolvable minerals of rocks can be employed to develop innovative technology in mining and oil extracting engineering. This paper presents a new alt...The natural phenomenon associated with the chemical dissolution of dissolvable minerals of rocks can be employed to develop innovative technology in mining and oil extracting engineering. This paper presents a new alternative approach for theoretically dealing with chemical dissolution front （CDF） propagation in fluid-saturated carbonate rocks. Note that the CDF is represented by the porosity front in this study. In this new approach, the porosity, pore-fluid velocity and acid concentration are directly used as independent variables. To illustrate how to use the present new approach, an aeidization dissolution system （ADS） consisting of carbonate rocks, which belongs to one of the many general chemical dissolution systems （CDSs）, is taken as an application example. When the acid dissolution capacity （ADC） number （that is defined as the ratio of the volume of the carbonate rock dissolved by an acid to that of the acid） approaches zero, the present new approach can be used to obtain analytical solutions for the stable ADS. However, if the ADC number is a nonzero finite number, then numerical solutions can be only obtained for the ADS, especially when the ADS is in an unstable state. The related theoretical results have demonstrated that： （1） When the ADS is in a stable state and in the case of the ADC number approaching zero, the present new approach is mathematically equivalent to the previous approach, in which the porosity, pore-fluid pressure and acid concentration are used as independent variables. However, when the ADS is in an unstable state, the use of the present new approach leads to a free parameter that needs to be determined by some other ways. （2） The existence of a non-step-type dissolution front within a transient region should at least satisfy that none of the ADC number, injected acid velocity and reciprocal of the dissolution reaction rate is equal to zero in the stable ADS.展开更多
The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by ...The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.展开更多
This study presents an in-depth analysis of the integration of environmental education within various curricula and its effectiveness in fostering critical thinking and environmental awareness among students.Through a...This study presents an in-depth analysis of the integration of environmental education within various curricula and its effectiveness in fostering critical thinking and environmental awareness among students.Through a comparative approach,the research evaluated the impact of different teaching methods and curriculum designs on students’learning outcomes.Key findings indicate that interdisciplinary environmental education significantly enhances students’understanding of sustainability issues and their ability to engage critically with environmental challenges.The study also highlights the importance of community involvement and governmental policy support for the successful implementation of environmental education programs.Innovative teaching methods,including inquiry-based and project-based learning,were found to be particularly effective in increasing student engagement and learning.The research concludes with recommendations for future studies to expand the scope of investigation,explore long-term impacts,and leverage technology to enhance environmental education.The findings of this study are instrumental for policymakers,educators,and curriculum developers in their efforts to cultivate a more environmentally literate and responsible generation.展开更多
Recent calls for promoting students＇ critical thinking （CT） abilities leave second language （L2） teachers wondering how to integrate CT into their existing agenda. Framed by Paul and Elder＇s （2001） CT model, t...Recent calls for promoting students＇ critical thinking （CT） abilities leave second language （L2） teachers wondering how to integrate CT into their existing agenda. Framed by Paul and Elder＇s （2001） CT model, the study explores how CT could be effectively taught in L2 writing as a way to improve students＇ CT skills and L2 writing performance. In this study, an infusion approach was developed and implemented in actual classroom teaching. Mixed methods were employed to investigate： （1） the effectiveness of the infusion approach on improving students＇ CT and L2 writing scores; （2） the relationship between students＇ CT and L2 writing scores; and （3） the effects of the infusion approach on students＇ learning of CT and L2 writing. The results of the statistical analyses indicate that the infusion approach has effectively improved students＇ CT and L2 writing scores and that there was a significant positive relationship （r=0.893, p〈0.01） between students＇ CT and L2 writing scores. The results of the post-study interview illustrate that the infusion approach has beneficial effects on students＇ learning of CT and L2 writing by bridging the abstract CT theories and interactive writing activities and by integrating the instruction and practice of CT into those of L2 writing.展开更多
Failure analysis of railway draw-hook coupler was carried out.The nondestructive testing method was undertaken on some failed couplers in service to designate critical areas of a coupler.Draw-Hook coupler is used to c...Failure analysis of railway draw-hook coupler was carried out.The nondestructive testing method was undertaken on some failed couplers in service to designate critical areas of a coupler.Draw-Hook coupler is used to connect with the same hook coupler or automatic coupler.The influence of each connection types on the coupler strength in this study was discussed.A numerical stress analysis using FEM was performed,and many approaches including critical plane approach were carried out on fatigue life prediction of coupler under different conditions.The results of the proposed fatigue criterion and fatigue life predictions,as well as static numerical analysis,are validated with experimental results.展开更多
The seismic analysis of a viscoelastic half-space under two-dimensional(2D)oblique incident waves is carried out by the finite/infinite element method(FIEM).First,the frequency-domain exact solutions for the displacem...The seismic analysis of a viscoelastic half-space under two-dimensional(2D)oblique incident waves is carried out by the finite/infinite element method(FIEM).First,the frequency-domain exact solutions for the displacements and stresses of the free field are derived in general form for arbitrary incident P and SV waves.With the present formulation,no distinction needs to be made for SV waves with over-critical incident angles that make the reflected P waves disappear,while no critical angle exists for P waves.Next,the equivalent seismic forces of the earthquake(Taft Earthquake 1952)imposed on the near-field boundary are generated by combining the solutions for unit ground accelerations with the earthquake spectrum.Based on the asymmetric finite/infinite element model,the frequency-domain motion equations for seismic analysis are presented with the key parameters selected.The results obtained in frequency and time domain are verified against those of Wolf’s,Luco and de Barros’and for inversely computed ground motions.The parametric study indicated that distinct phase difference exists between the horizontal and vertical responses for SV waves with over-critical incident angles,but not for under-critical incident angles.Other observations were also made for the numerical results inside the text.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11272359)
文摘The natural phenomenon associated with the chemical dissolution of dissolvable minerals of rocks can be employed to develop innovative technology in mining and oil extracting engineering. This paper presents a new alternative approach for theoretically dealing with chemical dissolution front （CDF） propagation in fluid-saturated carbonate rocks. Note that the CDF is represented by the porosity front in this study. In this new approach, the porosity, pore-fluid velocity and acid concentration are directly used as independent variables. To illustrate how to use the present new approach, an aeidization dissolution system （ADS） consisting of carbonate rocks, which belongs to one of the many general chemical dissolution systems （CDSs）, is taken as an application example. When the acid dissolution capacity （ADC） number （that is defined as the ratio of the volume of the carbonate rock dissolved by an acid to that of the acid） approaches zero, the present new approach can be used to obtain analytical solutions for the stable ADS. However, if the ADC number is a nonzero finite number, then numerical solutions can be only obtained for the ADS, especially when the ADS is in an unstable state. The related theoretical results have demonstrated that： （1） When the ADS is in a stable state and in the case of the ADC number approaching zero, the present new approach is mathematically equivalent to the previous approach, in which the porosity, pore-fluid pressure and acid concentration are used as independent variables. However, when the ADS is in an unstable state, the use of the present new approach leads to a free parameter that needs to be determined by some other ways. （2） The existence of a non-step-type dissolution front within a transient region should at least satisfy that none of the ADC number, injected acid velocity and reciprocal of the dissolution reaction rate is equal to zero in the stable ADS.
基金funding support from the National Key Research and Development Program of China(Grant No.2023YFB2604004)the National Natural Science Foundation of China(Grant No.52108374)the“Taishan”Scholar Program of Shandong Province,China(Grant No.tsqn201909016)。
文摘The expansion of a thick-walled hollow cylinder in soil is of non-self-similar nature that the stress/deformation paths are not the same for different soil material points.As a result,this problem cannot be solved by the common self-similar-based similarity techniques.This paper proposes a novel,exact solution for rigorous drained expansion analysis of a hollow cylinder of critical state soils.Considering stress-dependent elastic moduli of soils,new analytical stress and displacement solutions for the nonself-similar problem are developed taking the small strain assumption in the elastic zone.In the plastic zone,the cavity expansion response is formulated into a set of first-order partial differential equations(PDEs)with the combination use of Eulerian and Lagrangian descriptions,and a novel solution algorithm is developed to efficiently solve this complex boundary value problem.The solution is presented in a general form and thus can be useful for a wide range of soils.With the new solution,the non-self-similar nature induced by the finite outer boundary is clearly demonstrated and highlighted,which is found to be greatly different to the behaviour of cavity expansion in infinite soil mass.The present solution may serve as a benchmark for verifying the performance of advanced numerical techniques with critical state soil models and be used to capture the finite boundary effect for pressuremeter tests in small-sized calibration chambers.
文摘This study presents an in-depth analysis of the integration of environmental education within various curricula and its effectiveness in fostering critical thinking and environmental awareness among students.Through a comparative approach,the research evaluated the impact of different teaching methods and curriculum designs on students’learning outcomes.Key findings indicate that interdisciplinary environmental education significantly enhances students’understanding of sustainability issues and their ability to engage critically with environmental challenges.The study also highlights the importance of community involvement and governmental policy support for the successful implementation of environmental education programs.Innovative teaching methods,including inquiry-based and project-based learning,were found to be particularly effective in increasing student engagement and learning.The research concludes with recommendations for future studies to expand the scope of investigation,explore long-term impacts,and leverage technology to enhance environmental education.The findings of this study are instrumental for policymakers,educators,and curriculum developers in their efforts to cultivate a more environmentally literate and responsible generation.
文摘Recent calls for promoting students＇ critical thinking （CT） abilities leave second language （L2） teachers wondering how to integrate CT into their existing agenda. Framed by Paul and Elder＇s （2001） CT model, the study explores how CT could be effectively taught in L2 writing as a way to improve students＇ CT skills and L2 writing performance. In this study, an infusion approach was developed and implemented in actual classroom teaching. Mixed methods were employed to investigate： （1） the effectiveness of the infusion approach on improving students＇ CT and L2 writing scores; （2） the relationship between students＇ CT and L2 writing scores; and （3） the effects of the infusion approach on students＇ learning of CT and L2 writing. The results of the statistical analyses indicate that the infusion approach has effectively improved students＇ CT and L2 writing scores and that there was a significant positive relationship （r=0.893, p〈0.01） between students＇ CT and L2 writing scores. The results of the post-study interview illustrate that the infusion approach has beneficial effects on students＇ learning of CT and L2 writing by bridging the abstract CT theories and interactive writing activities and by integrating the instruction and practice of CT into those of L2 writing.
文摘Failure analysis of railway draw-hook coupler was carried out.The nondestructive testing method was undertaken on some failed couplers in service to designate critical areas of a coupler.Draw-Hook coupler is used to connect with the same hook coupler or automatic coupler.The influence of each connection types on the coupler strength in this study was discussed.A numerical stress analysis using FEM was performed,and many approaches including critical plane approach were carried out on fatigue life prediction of coupler under different conditions.The results of the proposed fatigue criterion and fatigue life predictions,as well as static numerical analysis,are validated with experimental results.
基金sponsored by the following agencies:National Natural Science Foundation of China(Grant No.52078082)Chongqing Science and Technology Commission(No.cstc2019yszx-jcyjX0001,cstc2020yszx-jscxX0002,and cstc2021yszxjscxX0001).
文摘The seismic analysis of a viscoelastic half-space under two-dimensional(2D)oblique incident waves is carried out by the finite/infinite element method(FIEM).First,the frequency-domain exact solutions for the displacements and stresses of the free field are derived in general form for arbitrary incident P and SV waves.With the present formulation,no distinction needs to be made for SV waves with over-critical incident angles that make the reflected P waves disappear,while no critical angle exists for P waves.Next,the equivalent seismic forces of the earthquake(Taft Earthquake 1952)imposed on the near-field boundary are generated by combining the solutions for unit ground accelerations with the earthquake spectrum.Based on the asymmetric finite/infinite element model,the frequency-domain motion equations for seismic analysis are presented with the key parameters selected.The results obtained in frequency and time domain are verified against those of Wolf’s,Luco and de Barros’and for inversely computed ground motions.The parametric study indicated that distinct phase difference exists between the horizontal and vertical responses for SV waves with over-critical incident angles,but not for under-critical incident angles.Other observations were also made for the numerical results inside the text.
