Purpose-The spatiotemporal compression effect of China-Europe Railway Express(CR-Express)can reduce the filow costs of resources between China's node cities.Additionally,it can break through the limitations of low...Purpose-The spatiotemporal compression effect of China-Europe Railway Express(CR-Express)can reduce the filow costs of resources between China's node cities.Additionally,it can break through the limitations of low-added-value marine products,significantly impacting the logistics industry efficiency.However,there are few literature verifying and analyzing its heterogeneity.This study explores the impact of CR-Express on the efficiency of logistics industry in node cities and analyzes the heterogeneity.Design/methodology/approach-First,this study uses panel data to measure the efficiency of node city logistics industry.Secondiy,this study discusses the impact of the opening of CR-Express on the efficiency of logistics industry in node cities based on the multi-period differential model.Finally,according to the node city difference,the sample city experimental group is grouped for heterogeneity analysis.Findings-The results show that CR-Express can promote the urban logistics industry efficiency,with an average effect of 4.55%.According to the urban characteristics classification,the heterogeneity analysis shows that the efficiency improvement effect of logistics industry in inland cities is more obvious.The improvement effect of node cities and central cities in central and western China is stronger,especially in the sample of megacities and type I big cities.Compared with non-value chain industrial products,the CR-Express has significant promotion effects on the logistics efficiency of the cities where main goods are value chain products.Originality/value-Under the background of double cycle development,this paper can provide a scientific basis for the investment benefit evaluation of CR-Express construction and the follow-up route planning.展开更多
On October 8,the'Belt and Road'Leading Group office published the'ChinaEurope Freight Train Development Plan',which is a fiveyear plan in accordance with China’s13th'Five-Year Plan'.The docume...On October 8,the'Belt and Road'Leading Group office published the'ChinaEurope Freight Train Development Plan',which is a fiveyear plan in accordance with China’s13th'Five-Year Plan'.The document formulated the major tasks for the construction of China-Europe freight train project for the next five years,and clarified three space layouts,including the China-Europe展开更多
This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double...This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.展开更多
The 2019 China-Europe Seminar on Human Rights hosted by the China Society for Human Rights Studies and Austria-China Friendship Association was successfully held in Austria on June 21,2019.Through this conference,Chin...The 2019 China-Europe Seminar on Human Rights hosted by the China Society for Human Rights Studies and Austria-China Friendship Association was successfully held in Austria on June 21,2019.Through this conference,China,as an important representative of Eastern countries of human rights,demonstrated its fruitful theoretical and practical human rights achievements to European countries.The conference also witnessed lively communication and exchanges on human rights values and the human rights discourse system between China and the West,during which scholars of the East and the West discussed the universality and particularity of human rights,and the evolution of human rights under different historical and cultural values.The conference advocated that the concept of a community with a shared future for human beings proposed by China should be incorporated into human rights governance of sovereign states and the international community.The convergence and integration of the human rights concepts of the East and the West will inevitably lead human rights practices of the East and the West to embark on a new journey.展开更多
Based on the blockchain technology to construct the relevant research on the China-Europe cross-border e-commerce ecosystem,we must first define the main significance and combine the core technology application of blo...Based on the blockchain technology to construct the relevant research on the China-Europe cross-border e-commerce ecosystem,we must first define the main significance and combine the core technology application of blockchain to explore the blockchain China-Europe cross-border e-commerce ecosystem,thereby drawing effective measures such as establishing a cross-border e-commerce integrated service system,improving e-commerce credit risk management and establishing a blockchain supply chain intelligence system,which comprehensively elaborates on the importance of blockchain technology to build a China-Europe cross-border e-commerce ecosystem.展开更多
Human rights are an achievement of humanity and a symbol of progress.Respect for and protection of human rights are basic principles of modern civilization.Around the world,countries and regions have chosen different ...Human rights are an achievement of humanity and a symbol of progress.Respect for and protection of human rights are basic principles of modern civilization.Around the world,countries and regions have chosen different paths to modernization,which are rooted in their unique civilizations.to promote exchanges and mutual learning among civilizations,facilitate human rights exchanges and cooperation between different countries,and advance the global development of human rights,on September 20,2023,the 2023 China-europe Seminar on Human Rights was held in Rome,the capital of Italy.Under the theme of“Modernization and the Diversity of Human Rights Among Civilizations,”the seminar focused on discussing topics such as exchanges and mutual learning among civilizations and the development of modern human rights philosophy,modernization and the free and well-rounded development of every person,sustainable development in the process of modernization,and the evolution of the civilization of human rights in the digital age.participants reached the following consensuses at the event:First,the participants from various countries spoke highly of the great achievements that China has made in human rights cause and fully recognized China’s contributions in promoting the development and progress of the global human rights cause;Second,the participants from all countries agreed that it is necessary to discard the concept of“Western-centrism,”transcend the mindset of“cultural superiority,”promote human rights exchanges and mutual learning among civilizations on the basis of equality and mutual respect,and inject new impetus into the diversity of human rights among civilizations;third,participants reaffirmed that human rights represent an open concept,and that we should discuss the development of human rights with an open mind and jointly promote the progress of human rights in the world.展开更多
Aiming at the problems of large load of rotation drive system,low efficiency of torque transmission and high cost for operation and maintenance of liner steering drilling system for the horizontal well,a new method of...Aiming at the problems of large load of rotation drive system,low efficiency of torque transmission and high cost for operation and maintenance of liner steering drilling system for the horizontal well,a new method of liner differential rotary drilling with double tubular strings in the horizontal well is proposed.The technical principle of this method is revealed,supporting tools such as the differential rotation transducer,composite rotary steering system and the hanger are designed,and technological process is optimized.A tool face control technique of steering drilling assembly is proposed and the calculation model of extension limit of liner differential rotary drilling with double tubular strings in horizontal well is established.These results show that the liner differential rotary drilling with double tubular strings is equipped with measurement while drilling(MWD)and positive displacement motor(PDM),and directional drilling of horizontal well is realized by adjusting rotary speed of drill pipe to control the tool face of PDM.Based on the engineering case of deep coalbed methane horizontal well in the eastern margin of Ordos Basin,the extension limit of horizontal drilling with double tubular strings is calculated.Compared with the conventional liner drilling method,the liner differential rotary drilling with double tubular strings increases the extension limit value of horizontal well significantly.The research findings provide useful reference for the integrated design and control of liner completion and drilling of horizontal wells.展开更多
In this study,a machine vision method is proposed to characterize 3D roughness of the textured surface on cylinder liner processed by plateau honing.The least absolute value(L∞)regression robust algorithm and Levenbe...In this study,a machine vision method is proposed to characterize 3D roughness of the textured surface on cylinder liner processed by plateau honing.The least absolute value(L∞)regression robust algorithm and Levenberg-Marquardt(LM)algorithm are employed to reconstruct image reference plane.On this basis,a single-hidden layer feedforward neural network(SLFNN)based on the extreme learning machine(ELM)is employed to model the relationship between high frequency information and 3D roughness.The characteristic parameters of Abbott-Firestone curve and 3D roughness measured by a confocal microscope are used to construct ELM-SLFNN prediction model for 3D roughness.The results indicate that the proposed method can effectively characterize 3D roughness of the textured surface of cylinder liner.展开更多
Shaped charge liner(SCL)has been extensively applied in oil recovery and defense industries.Achieving superior penetration capability through optimizing SCL structures presents a substantial challenge due to intricate...Shaped charge liner(SCL)has been extensively applied in oil recovery and defense industries.Achieving superior penetration capability through optimizing SCL structures presents a substantial challenge due to intricate rate-dependent processes involving detonation-driven liner collapse,high-speed jet stretching,and penetration.This study introduces an innovative optimization strategy for SCL structures that employs jet penetration efficiency as the primary objective function.The strategy combines experimentally validated finite element method with machine learning(FEM-ML).We propose a novel jet penetration efficiency index derived from enhanced cutoff velocity and shape characteristics of the jet via machine learning.This index effectively evaluates the jet penetration performance.Furthermore,a multi-model fusion based on a machine learning optimization method,called XGBOOST-MFO,is put forward to optimize SCL structure over a large input space.The strategy's feasibility is demonstrated through the optimization of copper SCL implemented via the FEM-ML strategy.Finally,this strategy is extended to optimize the structure of the recently emerging CrMnFeCoNi high-entropy alloy conical liners and hemispherical copper liners.Therefore,the strategy can provide helpful guidance for the engineering design of SCL.展开更多
Based on the ablation micro-morphological characteristics, thermo-chemical ablation mechanism, and mechanical stripping mechanism, a dual-region solid rocket motor C/C throat liner ablation model and physical model ar...Based on the ablation micro-morphological characteristics, thermo-chemical ablation mechanism, and mechanical stripping mechanism, a dual-region solid rocket motor C/C throat liner ablation model and physical model are established. The ablation program was written and the experimental data of 70 lb BATES engine platform was used for model validation. The relative errors between the simulation calculation results and the experimental results were −6.83% - 10.20%. The ablation program was applied to study the effects of combustion chamber temperature, pressure, oxidation component concentration, throat particle concentration and particle scouring angle on the nozzle throat liner, which provides a reference for the design of the nozzle throat liner and the estimation of solid rocket motor ablation.展开更多
A new method for manufacturing explosive charge liner of petroleum perforation bullet, using hot press sintering technique, has been introduced in the paper. The sintering process of making explosive charge liner has...A new method for manufacturing explosive charge liner of petroleum perforation bullet, using hot press sintering technique, has been introduced in the paper. The sintering process of making explosive charge liner has been investigated. The mechanical test and SEM analysis indicate that the property of the liner produced by the process is satisfied.展开更多
The equivalence between multilayered barriers regarding diffusion and adsorption was studied. The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of t...The equivalence between multilayered barriers regarding diffusion and adsorption was studied. The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of the contaminant between the bottom liner layer and the underlying soil. Five different liner systems were compared in terms of solute breakthrough time. The results of the analysis showed that breakthrough time of the hydrophobic organic compounds for a 2-meter-thick compacted clay liner (CCL) could be 3-4 orders of magnitude is greater than the breakthrough time for a geosynthetic clay liner (GCL) composite liner. The GM/GCL and GM/CCL composite liner systems provide a better diffusion barrier for the hydrophilic organic compounds than that for the hydrophobic compounds due to their different Henry's coefficient. The calculated breakthrough times of the organic contaminants for the Chinese standard liner systems were found to be generally greater than those for the GCL alternatives, for the specific conditions examined. If the distribution coefficient increases to 2.8 for the hydrophobic compounds or 1.0 for the hydrophilic compounds, the thickness of the attenuation layer needed to achieve the same breakthrough time as the standard liner systems can be reduced by a factor of about 1.9-2.4. As far as diffusive and adsorption contaminant transport are concerned, GM or GCL is less effective than CCL.展开更多
In the dry-sliding process of the woven self-lubricating liner which is used in the self-lubricating spherical plain bearing, the friction heat plays an important role in the tribological performances of the liner. It...In the dry-sliding process of the woven self-lubricating liner which is used in the self-lubricating spherical plain bearing, the friction heat plays an important role in the tribological performances of the liner. It has important value to study on the relationship between tribological performances of the liner and the friction heat. Unforttmately, up to now, published work on this relationship is quite scarce. Therefore, the effect of friction heat on the tribological performances of the liner was investigated in the present work. The tribological behaviors of the liner were evaluated by using the high temperature end surface wear tester. Scanning electron microscopy (SEM) was utilized to examine the morphologies of worn surfaces of the liner and study the failure modes. Differential scanning calorimetry (DSC) measurement and X-ray diffraction (XRD) analysis were performed to study the behaviors of the wear debris. The temperature rise on the worn surface was calculated according to classical models. SEM observation shows that the dominating wear mechanism for the liner is mainly affected by friction shear force, contact pressure and friction heat. Higher fusion heat for the wear debris than that for the pure polytetrafluroethylene (PTFE) indicates that the PTFE is the main portion of the wear debris, and, the PTFE in the wear debris shows a higher crystallisation degree owing to the effects of friction shear force and the friction heat. Combining the calculated temperature rise results with the wear rate of the liner, it can be concluded that the effects of temperature rise o n the tribological performances of the liner become more obvious when the temperature rise exceeds the glass transition temperature (Tg) of the PTFE. The wear resistance of the liner deteriorates dramatically when the temperature rise approaches to the melting point (Ton) of the PTFE. The tribological performances of the liner can be improved when the temperature rise exceeds Tg but is far lower than Ton- The present study on the relationship between the temperature rise and the tribological performances of the liner may provide the basis for further understanding of the wear mechanisms of the liner as well as the relationship between the formation of the PTFE transfer film and the friction heat during the dry-sliding of the Finer.展开更多
According to relevant new regulations in China,a composite liner system involving geosynthetic materials must be installed at the bottom of an expanded landfill.The deformation and integrity of the composite liner und...According to relevant new regulations in China,a composite liner system involving geosynthetic materials must be installed at the bottom of an expanded landfill.The deformation and integrity of the composite liner under a variety of factors are important issue to be considered in the design of a landfill expansion.In this paper,we investigate the strain distribution in geosynthetic materials within the composite liner system of expanded landfills,including strains in geosynthetic materials resulting from overall settlement and lateral movement of landfills,localized subsidence in landfills,and differential settlement around gas venting wells.The allowable strains of geosynthetic materials are discussed based on the results of tensile tests,and the corresponding design criteria for composite liner systems are proposed.Meanwhile,practical measures allowing strain control in geosynthetic materials used in landfill engineering are proposed.展开更多
基金National Natural Science Foundation of China(No.72071133)Hebei Provincial Department of Education Humanities and Social Science Research Major Projects(No.ZD202309).
文摘Purpose-The spatiotemporal compression effect of China-Europe Railway Express(CR-Express)can reduce the filow costs of resources between China's node cities.Additionally,it can break through the limitations of low-added-value marine products,significantly impacting the logistics industry efficiency.However,there are few literature verifying and analyzing its heterogeneity.This study explores the impact of CR-Express on the efficiency of logistics industry in node cities and analyzes the heterogeneity.Design/methodology/approach-First,this study uses panel data to measure the efficiency of node city logistics industry.Secondiy,this study discusses the impact of the opening of CR-Express on the efficiency of logistics industry in node cities based on the multi-period differential model.Finally,according to the node city difference,the sample city experimental group is grouped for heterogeneity analysis.Findings-The results show that CR-Express can promote the urban logistics industry efficiency,with an average effect of 4.55%.According to the urban characteristics classification,the heterogeneity analysis shows that the efficiency improvement effect of logistics industry in inland cities is more obvious.The improvement effect of node cities and central cities in central and western China is stronger,especially in the sample of megacities and type I big cities.Compared with non-value chain industrial products,the CR-Express has significant promotion effects on the logistics efficiency of the cities where main goods are value chain products.Originality/value-Under the background of double cycle development,this paper can provide a scientific basis for the investment benefit evaluation of CR-Express construction and the follow-up route planning.
文摘On October 8,the'Belt and Road'Leading Group office published the'ChinaEurope Freight Train Development Plan',which is a fiveyear plan in accordance with China’s13th'Five-Year Plan'.The document formulated the major tasks for the construction of China-Europe freight train project for the next five years,and clarified three space layouts,including the China-Europe
基金funded by the China Postdoctoral Science Foundation(Grant No.2022M721614)the opening project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(Grant No.KFJJ23-07M)。
文摘This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner.
文摘The 2019 China-Europe Seminar on Human Rights hosted by the China Society for Human Rights Studies and Austria-China Friendship Association was successfully held in Austria on June 21,2019.Through this conference,China,as an important representative of Eastern countries of human rights,demonstrated its fruitful theoretical and practical human rights achievements to European countries.The conference also witnessed lively communication and exchanges on human rights values and the human rights discourse system between China and the West,during which scholars of the East and the West discussed the universality and particularity of human rights,and the evolution of human rights under different historical and cultural values.The conference advocated that the concept of a community with a shared future for human beings proposed by China should be incorporated into human rights governance of sovereign states and the international community.The convergence and integration of the human rights concepts of the East and the West will inevitably lead human rights practices of the East and the West to embark on a new journey.
文摘Based on the blockchain technology to construct the relevant research on the China-Europe cross-border e-commerce ecosystem,we must first define the main significance and combine the core technology application of blockchain to explore the blockchain China-Europe cross-border e-commerce ecosystem,thereby drawing effective measures such as establishing a cross-border e-commerce integrated service system,improving e-commerce credit risk management and establishing a blockchain supply chain intelligence system,which comprehensively elaborates on the importance of blockchain technology to build a China-Europe cross-border e-commerce ecosystem.
文摘Human rights are an achievement of humanity and a symbol of progress.Respect for and protection of human rights are basic principles of modern civilization.Around the world,countries and regions have chosen different paths to modernization,which are rooted in their unique civilizations.to promote exchanges and mutual learning among civilizations,facilitate human rights exchanges and cooperation between different countries,and advance the global development of human rights,on September 20,2023,the 2023 China-europe Seminar on Human Rights was held in Rome,the capital of Italy.Under the theme of“Modernization and the Diversity of Human Rights Among Civilizations,”the seminar focused on discussing topics such as exchanges and mutual learning among civilizations and the development of modern human rights philosophy,modernization and the free and well-rounded development of every person,sustainable development in the process of modernization,and the evolution of the civilization of human rights in the digital age.participants reached the following consensuses at the event:First,the participants from various countries spoke highly of the great achievements that China has made in human rights cause and fully recognized China’s contributions in promoting the development and progress of the global human rights cause;Second,the participants from all countries agreed that it is necessary to discard the concept of“Western-centrism,”transcend the mindset of“cultural superiority,”promote human rights exchanges and mutual learning among civilizations on the basis of equality and mutual respect,and inject new impetus into the diversity of human rights among civilizations;third,participants reaffirmed that human rights represent an open concept,and that we should discuss the development of human rights with an open mind and jointly promote the progress of human rights in the world.
基金Supported by the Project of National Natural Science Foundation of China(52234002,42230814)。
文摘Aiming at the problems of large load of rotation drive system,low efficiency of torque transmission and high cost for operation and maintenance of liner steering drilling system for the horizontal well,a new method of liner differential rotary drilling with double tubular strings in the horizontal well is proposed.The technical principle of this method is revealed,supporting tools such as the differential rotation transducer,composite rotary steering system and the hanger are designed,and technological process is optimized.A tool face control technique of steering drilling assembly is proposed and the calculation model of extension limit of liner differential rotary drilling with double tubular strings in horizontal well is established.These results show that the liner differential rotary drilling with double tubular strings is equipped with measurement while drilling(MWD)and positive displacement motor(PDM),and directional drilling of horizontal well is realized by adjusting rotary speed of drill pipe to control the tool face of PDM.Based on the engineering case of deep coalbed methane horizontal well in the eastern margin of Ordos Basin,the extension limit of horizontal drilling with double tubular strings is calculated.Compared with the conventional liner drilling method,the liner differential rotary drilling with double tubular strings increases the extension limit value of horizontal well significantly.The research findings provide useful reference for the integrated design and control of liner completion and drilling of horizontal wells.
基金Supported by National Natural Science Foundation of China(Grant No.52075438)Key Research and Development Program of Shaanxi Province of China(Grant No.2024GX-YBXM-268)Open Project of State Key Laboratory for Manufacturing Systems Engineering of China(Grant No.sklms2020010).
文摘In this study,a machine vision method is proposed to characterize 3D roughness of the textured surface on cylinder liner processed by plateau honing.The least absolute value(L∞)regression robust algorithm and Levenberg-Marquardt(LM)algorithm are employed to reconstruct image reference plane.On this basis,a single-hidden layer feedforward neural network(SLFNN)based on the extreme learning machine(ELM)is employed to model the relationship between high frequency information and 3D roughness.The characteristic parameters of Abbott-Firestone curve and 3D roughness measured by a confocal microscope are used to construct ELM-SLFNN prediction model for 3D roughness.The results indicate that the proposed method can effectively characterize 3D roughness of the textured surface of cylinder liner.
基金supported by the NSFC Basic Science Center Program for"Multi-scale Problems in Nonlinear Mechanics" (Grant No.11988102)the NSFC (Grant Nos.U2141204,12172367)+2 种基金the Key Research Program of the Chinese Academy of Sciences (Grant No.ZDRW-CN-2021-2-3)the National Key Research and Development Program of China (Grant No.2022YFC3320504-02)the opening project of State Key Laboratory of Explosion Science and Technology (Grant No.KFJJ21-01 and No.KFJJ18-14 M)。
文摘Shaped charge liner(SCL)has been extensively applied in oil recovery and defense industries.Achieving superior penetration capability through optimizing SCL structures presents a substantial challenge due to intricate rate-dependent processes involving detonation-driven liner collapse,high-speed jet stretching,and penetration.This study introduces an innovative optimization strategy for SCL structures that employs jet penetration efficiency as the primary objective function.The strategy combines experimentally validated finite element method with machine learning(FEM-ML).We propose a novel jet penetration efficiency index derived from enhanced cutoff velocity and shape characteristics of the jet via machine learning.This index effectively evaluates the jet penetration performance.Furthermore,a multi-model fusion based on a machine learning optimization method,called XGBOOST-MFO,is put forward to optimize SCL structure over a large input space.The strategy's feasibility is demonstrated through the optimization of copper SCL implemented via the FEM-ML strategy.Finally,this strategy is extended to optimize the structure of the recently emerging CrMnFeCoNi high-entropy alloy conical liners and hemispherical copper liners.Therefore,the strategy can provide helpful guidance for the engineering design of SCL.
文摘Based on the ablation micro-morphological characteristics, thermo-chemical ablation mechanism, and mechanical stripping mechanism, a dual-region solid rocket motor C/C throat liner ablation model and physical model are established. The ablation program was written and the experimental data of 70 lb BATES engine platform was used for model validation. The relative errors between the simulation calculation results and the experimental results were −6.83% - 10.20%. The ablation program was applied to study the effects of combustion chamber temperature, pressure, oxidation component concentration, throat particle concentration and particle scouring angle on the nozzle throat liner, which provides a reference for the design of the nozzle throat liner and the estimation of solid rocket motor ablation.
文摘A new method for manufacturing explosive charge liner of petroleum perforation bullet, using hot press sintering technique, has been introduced in the paper. The sintering process of making explosive charge liner has been investigated. The mechanical test and SEM analysis indicate that the property of the liner produced by the process is satisfied.
基金supported by the National Science Fundfor Distinguished Young Scholars (No. 50425825)the National Natural Science Foundation of China (No.50538080)
文摘The equivalence between multilayered barriers regarding diffusion and adsorption was studied. The bottom boundary of the liner system is defined by assuming concentration continuous and flux continuous conditions of the contaminant between the bottom liner layer and the underlying soil. Five different liner systems were compared in terms of solute breakthrough time. The results of the analysis showed that breakthrough time of the hydrophobic organic compounds for a 2-meter-thick compacted clay liner (CCL) could be 3-4 orders of magnitude is greater than the breakthrough time for a geosynthetic clay liner (GCL) composite liner. The GM/GCL and GM/CCL composite liner systems provide a better diffusion barrier for the hydrophilic organic compounds than that for the hydrophobic compounds due to their different Henry's coefficient. The calculated breakthrough times of the organic contaminants for the Chinese standard liner systems were found to be generally greater than those for the GCL alternatives, for the specific conditions examined. If the distribution coefficient increases to 2.8 for the hydrophobic compounds or 1.0 for the hydrophilic compounds, the thickness of the attenuation layer needed to achieve the same breakthrough time as the standard liner systems can be reduced by a factor of about 1.9-2.4. As far as diffusive and adsorption contaminant transport are concerned, GM or GCL is less effective than CCL.
文摘In the dry-sliding process of the woven self-lubricating liner which is used in the self-lubricating spherical plain bearing, the friction heat plays an important role in the tribological performances of the liner. It has important value to study on the relationship between tribological performances of the liner and the friction heat. Unforttmately, up to now, published work on this relationship is quite scarce. Therefore, the effect of friction heat on the tribological performances of the liner was investigated in the present work. The tribological behaviors of the liner were evaluated by using the high temperature end surface wear tester. Scanning electron microscopy (SEM) was utilized to examine the morphologies of worn surfaces of the liner and study the failure modes. Differential scanning calorimetry (DSC) measurement and X-ray diffraction (XRD) analysis were performed to study the behaviors of the wear debris. The temperature rise on the worn surface was calculated according to classical models. SEM observation shows that the dominating wear mechanism for the liner is mainly affected by friction shear force, contact pressure and friction heat. Higher fusion heat for the wear debris than that for the pure polytetrafluroethylene (PTFE) indicates that the PTFE is the main portion of the wear debris, and, the PTFE in the wear debris shows a higher crystallisation degree owing to the effects of friction shear force and the friction heat. Combining the calculated temperature rise results with the wear rate of the liner, it can be concluded that the effects of temperature rise o n the tribological performances of the liner become more obvious when the temperature rise exceeds the glass transition temperature (Tg) of the PTFE. The wear resistance of the liner deteriorates dramatically when the temperature rise approaches to the melting point (Ton) of the PTFE. The tribological performances of the liner can be improved when the temperature rise exceeds Tg but is far lower than Ton- The present study on the relationship between the temperature rise and the tribological performances of the liner may provide the basis for further understanding of the wear mechanisms of the liner as well as the relationship between the formation of the PTFE transfer film and the friction heat during the dry-sliding of the Finer.
基金Supported by the National Natural Science Foundation of China (50538080)
文摘According to relevant new regulations in China,a composite liner system involving geosynthetic materials must be installed at the bottom of an expanded landfill.The deformation and integrity of the composite liner under a variety of factors are important issue to be considered in the design of a landfill expansion.In this paper,we investigate the strain distribution in geosynthetic materials within the composite liner system of expanded landfills,including strains in geosynthetic materials resulting from overall settlement and lateral movement of landfills,localized subsidence in landfills,and differential settlement around gas venting wells.The allowable strains of geosynthetic materials are discussed based on the results of tensile tests,and the corresponding design criteria for composite liner systems are proposed.Meanwhile,practical measures allowing strain control in geosynthetic materials used in landfill engineering are proposed.