The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and t...The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and tends to be constant after 25 days regardless of the restraining conditions. The mixture ratio of expansive cement and restraining conditions are the main factors affecting expansive deformation. Self-stress can be obtained when the expansive deformation is restrained. The higher self-stress could be obtained when the expensive concrete is restrained by steel tube. For specimens under steel tube restraining, the wall thickness and the length of the steel tube have important influence on self-stress. Both the radial self-stress and axial self-stress in concrete core increase when wall thickness or length of the steel tube increases.展开更多
In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead ...In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important pa- rameters in sheet metal forming process control. This paper derives the model of loop drawbead restraining force (DBRF) using plastic forming theory, and gives the min imum blankholding force. Experiments are carried out to verify the proposed DBRF model. The good agreement between the calculated values and experiments data justi- fies the proposed loop drawbead restraining force model.展开更多
Due to complexities of draw-bead restraining force calculated according to theory and depending on sheet metal forming properties experiment testing system, a simplified method to calculate draw-bead restraining force...Due to complexities of draw-bead restraining force calculated according to theory and depending on sheet metal forming properties experiment testing system, a simplified method to calculate draw-bead restraining force is put forward by experimental method in cup-shaped drawing process. The experimental results were compared with numerical results and proved agreement. It shows the method is effective.展开更多
The extracts from leaves of Manglietia insignis (Wall) Blume, Manglietia chingii Dandy and Manglietia yuyuanensis Law were prepared by organic solvent extraction and their components were analyzed by GC/MS and quant...The extracts from leaves of Manglietia insignis (Wall) Blume, Manglietia chingii Dandy and Manglietia yuyuanensis Law were prepared by organic solvent extraction and their components were analyzed by GC/MS and quantified. Meanwhile, the free radicals restraining activities were detected. The 21 compounds in M. insignis, 36 compounds in M. chigii and 20 compounds in M. yuyuanensis were identified. There were 11 common components in the extracts from three Manglietia species, and 12 components in two Manglietia species. The results of relative contents of every component in three extracts showed that the main constituents of M. insignis were terpenoids and alkene, amounting to 38.93%, followed by alkane (28.18%), the nitrogen containing compounds (15.73%) and aromatic compounds (7.23 %). The main constituents of leaf extract from M. chingii were the terpenoids and alkene, carboxylic acid, alkane and aromatic compounds, amounting to 30.22%, 14.17%, 13.87% and 13.29%, respectively, The main constituents of M. yuyuanensis were alcohol compounds, the terpenoids and alkene, and aromatic compounds, amounting to 28.00%, 25.38% and 18.00% respectively. The results showed that the three extracts had strong function of restraining oxygen free radicals. The ultra oxygen anions activity was restrained at the highest level, when the three extracts were diluted by hundred-fold, whereas the restraining capacity of hydroxyl free radicals reached maximum, when the three extracts were diluted by twenty-fold. The above results provide scientific evidences for further approaching the ecological healthy function of three MangUetia species展开更多
The method of planning acceleration is discussed to restrain the residual vibration of flexible arm. Based on the built mathematical model of the flexible arm, the equations of vibration with acceleration,vibration f...The method of planning acceleration is discussed to restrain the residual vibration of flexible arm. Based on the built mathematical model of the flexible arm, the equations of vibration with acceleration,vibration frequency,damping and time are obtained theoretically.According to the vibration frequency and damping, the suitable acceleration is executed experimentally to the flexible arm at the corresponding time. The result shows that this way can give rise to good effect to restrain the residual vibration.展开更多
For a better understanding of the strains and stresses,numerical simulation was conducted by using ANSYS under the assumption of absolute bond between the steel and concrete.The results show that the stresses and stra...For a better understanding of the strains and stresses,numerical simulation was conducted by using ANSYS under the assumption of absolute bond between the steel and concrete.The results show that the stresses and strains in such concrete and steel rings are uneven;the curves of strains and stresses change gradually around the interface.To ease numerical computation,the mechanical system was simplified under the assumptions of synchronous deformation and uniform strains and stresses.The results of the numerical simulation and simplified stress calculation can match almost perfectly.It means that the simplified mechanical model can be used in stress and visco-elastic behavior quantification.展开更多
The effects of various combustion conditions (i. e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NO_x during coal combustion were st...The effects of various combustion conditions (i. e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NO_x during coal combustion were studied. Under the present combustion conditions, coals with smaller particle size gave the lower conversion of NO_x, and as expected that an decrease in overall stoichiometric ratio, whether by an decrease in O_2 content in combustion gas or by an increase in coal content in fuel bed would lead to a lower conversion of NO_x. In order to investigate the effect of metallic oxide layers on restraining NO_x formation, the combustion experiments for coal granules with adhering layer of various metallic oxides including Fe_2O_3, Ni_2O_3 and mixed oxides Fe-Ni-O_x were conducted in a packed bed combustor. The combustion experiments have shown that most of adhering materials gave considerable effect on reduction of NO_x emission during coal combustion.展开更多
The new rural cooperative medical system has achieved periodical achievements since its establishment.Nevertheless,there are many factors hampering the development of the new system,such as the high cost,the difficult...The new rural cooperative medical system has achieved periodical achievements since its establishment.Nevertheless,there are many factors hampering the development of the new system,such as the high cost,the difficulties in fund procurement,the lack of management,the narrow coverage of benefit,the ineffective constraint to the designated medical institutions,the high fund balance rate,and the poor medical facilities and services in rural areas.Countermeasures are put forward to solve these problems,including improving the system design,expanding the coverage of the system,expanding the fund sources,reducing the financing costs,strengthening the fund supervision,enhancing the supervision of designated medical institutions,and improving the capacity of health services in rural areas.展开更多
The T2/RNase gene family is widespread in eukaryotes,and particular members of this family play critical roles in the gametophytic self-incompatibility(GSI) system in plants.Wild diploid strawberry(Fragaria)species ha...The T2/RNase gene family is widespread in eukaryotes,and particular members of this family play critical roles in the gametophytic self-incompatibility(GSI) system in plants.Wild diploid strawberry(Fragaria)species have diversified their sexual systems via self-incompatible and self-compatible traits,yet how these traits evolved in Fragaria remains elusive.By integrating the published and de novo assembled genomes and the newly generated RNA-seq data,members of the RNase T2 gene family were systematically identified in six Fragaria species,including three self-incompatible species(Fragaria nipponica,Fragaria nubicola,and Fragaria viridis) and three self-compatible species(Fragaria nilgerrensis,Fragaria vesca,and Fragaria iinumae).In total,115 RNase T2 genes were identified in the six Fragaria genomes and can be classified into three classes(Ⅰ-Ⅲ) according to phylogenetic analysis.The identified RNase T2 genes could be divided into 22 homologous gene sets according to amino acid sequence similarity and phylogenetic and syntenic relationships.We found that extensive gene loss and pseudogenization coupled with small-scale duplications mainly accounted for variations in the RNase T2 gene numbers in Fragaria.Multiple copies of homologous genes were mainly generated from tandem and segmental duplication events.Furthermore,we newly identified five S-RNase genes in three self-incompatible Fragaria genomes,including two in F.nipponica,two in F.viridis,and one in F.nubicola,which fit for typical features of a pistil determinant,including highly pistil-specific expression,highly polymorphic proteins and alkaline isoelectric point(pI),while no S-RNase genes were found in all three selfcompatible Fragaria species.Surprisingly,these T2/S-RNase genes contain at least one large intron(>10 kb).This study revealed that the rapid evolution of T2/S-RNase genes within the Fragaria genus could be associated with its sexual mode,and repeated evolution of the self-compatible traits in Fragaria was convergent via losses of S-RNase.展开更多
The region coverage control problem of multiple stratospheric airships system is firstly addressed in this paper.Towards it,we propose a two-layer control framework with the artificial potential field(APF)-based regio...The region coverage control problem of multiple stratospheric airships system is firstly addressed in this paper.Towards it,we propose a two-layer control framework with the artificial potential field(APF)-based region coverage control law and the adaptive tracking control law.The APF-based region coverage control law ensures the coverage task is achieved until every single stratospheric airship ends up performing station keeping where near the respective global minimum point,in which an innovative solution to the local minimum problem is put forward.The adaptive tracking control law is designed to realize motion control using tracking the desired velocity and angular velocity given by coverage control law,with the consideration of several practical control problems as unknown individual differences and external disturbances.To save resources,the combined self-/event-triggered mechanism designed therein significantly reduces the times of state information transmission and control law calculation.The effectiveness of the proposed control framework is verified through simulations.展开更多
Metabolic rewiring underlies the effector functions of macrophages1-3,but the mechanisms involved remain incompletely defined.Here,using unbiased metabolomics and stable isotope-assisted tracing,we show that an inflam...Metabolic rewiring underlies the effector functions of macrophages1-3,but the mechanisms involved remain incompletely defined.Here,using unbiased metabolomics and stable isotope-assisted tracing,we show that an inflammatory aspartate argininosuccinate shunt is induced following lipopolysaccharide stimulation.The shunt,supported by increased argininosuccinate synthase(ASS1)expression,also leads to increased cytosolic fumarate levels and fumarate-mediated protein succination.Pharmacological inhibition and genetic ablation of the tricarboxylic acid cycle enzyme fumarate hydratase(FH)further increases intracellular fumarate levels.展开更多
This paper presents a simplified elastic continuum method for calculating the restraint effect of isolation piles on tunneling-induced vertical ground displacement,which can consider not only the relative sliding of t...This paper presents a simplified elastic continuum method for calculating the restraint effect of isolation piles on tunneling-induced vertical ground displacement,which can consider not only the relative sliding of the pile‒soil interface but also the pile rowesoil interaction.The proposed method is verified by comparisons with existing theoretical methods,including the boundary element method and the elastic foundation method.The results reveal the restraining mechanism of the isolation piles on vertical ground displacements due to tunneling,i.e.the positive and negative restraint effects exerted by the isolation piles jointly drive the ground vertical displacement along the depth direction from the original tunneling-induced nonlinear variation situation to a relatively uniform situation.The results also indicate that the stiffness of the pile‒soil interface,including the pile shaft‒surrounding soil interface and pile tip-supporting soil interface,describes the strength of the pile‒soil interaction.The pile rows can confine the vertical ground displacement caused by the tunnel excavation to the inner side of the isolation piles and effectively prevent the vertical ground displacement from expanding further toward the outer side of the isolation piles.展开更多
Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experi...Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experimental measurement and numerical simulation techniques. Comprehensive parametric studies are carried out to discuss the influence of end connection types, temperature, impact velocity,impact mass and span-to-depth ratio(SDR) on the dynamic response of the beams. The characteristics of deformation, internal force and energy distribution about the restrained beams and its joints are investigated. A temperature dependent criterion for evaluating the frame joint performance is proposed to measure the degree of performance degradation and impact resistance of the joint. The dynamic displacement amplification factor in different temperature environments are proposed for the different beam end constraint types and SDRs. Results of the experimental and numerical analysis show that the welded connection(WC) of three typical joint types is the strongest, and the extended endplate connection(EEC) is the weakest in terms of the impact resistance performance. With regard to the failure mode of the joint, the failure positions of the WC and the welded-bolted connection are located in the inner web of the column. Meanwhile, the EEC is located in the connection position between the beam and the endplate. Three different internal force stages and two obvious critical temperature boundaries of the restrained beams emerge with the increase in temperature, and they have significant characteristics in terms of deformation trend, internal force transfer and energy distribution. During the impact, a phenomenon known as “compression arch action” develops into “catenary action” with the increase in deflection in the frame beam mechanism.展开更多
基金Funded by the NSFC (No.50578027)the Key Subject Foundation of Henan Province (No.504906)the Doctor Foundation of Henan Polytechnic University (No.B2009-2)
文摘The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and tends to be constant after 25 days regardless of the restraining conditions. The mixture ratio of expansive cement and restraining conditions are the main factors affecting expansive deformation. Self-stress can be obtained when the expansive deformation is restrained. The higher self-stress could be obtained when the expensive concrete is restrained by steel tube. For specimens under steel tube restraining, the wall thickness and the length of the steel tube have important influence on self-stress. Both the radial self-stress and axial self-stress in concrete core increase when wall thickness or length of the steel tube increases.
文摘In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important pa- rameters in sheet metal forming process control. This paper derives the model of loop drawbead restraining force (DBRF) using plastic forming theory, and gives the min imum blankholding force. Experiments are carried out to verify the proposed DBRF model. The good agreement between the calculated values and experiments data justi- fies the proposed loop drawbead restraining force model.
基金Supported by Science and Technology Development Foundation of Shanghai (015211009).
文摘Due to complexities of draw-bead restraining force calculated according to theory and depending on sheet metal forming properties experiment testing system, a simplified method to calculate draw-bead restraining force is put forward by experimental method in cup-shaped drawing process. The experimental results were compared with numerical results and proved agreement. It shows the method is effective.
基金This paper was supported by the National "Eleven .Five" Scientific and Technological Supporting project "Test and demonstration for typical region city forest construction technol-ogy(2006BAD03A19) "
文摘The extracts from leaves of Manglietia insignis (Wall) Blume, Manglietia chingii Dandy and Manglietia yuyuanensis Law were prepared by organic solvent extraction and their components were analyzed by GC/MS and quantified. Meanwhile, the free radicals restraining activities were detected. The 21 compounds in M. insignis, 36 compounds in M. chigii and 20 compounds in M. yuyuanensis were identified. There were 11 common components in the extracts from three Manglietia species, and 12 components in two Manglietia species. The results of relative contents of every component in three extracts showed that the main constituents of M. insignis were terpenoids and alkene, amounting to 38.93%, followed by alkane (28.18%), the nitrogen containing compounds (15.73%) and aromatic compounds (7.23 %). The main constituents of leaf extract from M. chingii were the terpenoids and alkene, carboxylic acid, alkane and aromatic compounds, amounting to 30.22%, 14.17%, 13.87% and 13.29%, respectively, The main constituents of M. yuyuanensis were alcohol compounds, the terpenoids and alkene, and aromatic compounds, amounting to 28.00%, 25.38% and 18.00% respectively. The results showed that the three extracts had strong function of restraining oxygen free radicals. The ultra oxygen anions activity was restrained at the highest level, when the three extracts were diluted by hundred-fold, whereas the restraining capacity of hydroxyl free radicals reached maximum, when the three extracts were diluted by twenty-fold. The above results provide scientific evidences for further approaching the ecological healthy function of three MangUetia species
文摘The method of planning acceleration is discussed to restrain the residual vibration of flexible arm. Based on the built mathematical model of the flexible arm, the equations of vibration with acceleration,vibration frequency,damping and time are obtained theoretically.According to the vibration frequency and damping, the suitable acceleration is executed experimentally to the flexible arm at the corresponding time. The result shows that this way can give rise to good effect to restrain the residual vibration.
基金Funded by the National Natural Science Foundation of China (No.50678054)
文摘For a better understanding of the strains and stresses,numerical simulation was conducted by using ANSYS under the assumption of absolute bond between the steel and concrete.The results show that the stresses and strains in such concrete and steel rings are uneven;the curves of strains and stresses change gradually around the interface.To ease numerical computation,the mechanical system was simplified under the assumptions of synchronous deformation and uniform strains and stresses.The results of the numerical simulation and simplified stress calculation can match almost perfectly.It means that the simplified mechanical model can be used in stress and visco-elastic behavior quantification.
文摘The effects of various combustion conditions (i. e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NO_x during coal combustion were studied. Under the present combustion conditions, coals with smaller particle size gave the lower conversion of NO_x, and as expected that an decrease in overall stoichiometric ratio, whether by an decrease in O_2 content in combustion gas or by an increase in coal content in fuel bed would lead to a lower conversion of NO_x. In order to investigate the effect of metallic oxide layers on restraining NO_x formation, the combustion experiments for coal granules with adhering layer of various metallic oxides including Fe_2O_3, Ni_2O_3 and mixed oxides Fe-Ni-O_x were conducted in a packed bed combustor. The combustion experiments have shown that most of adhering materials gave considerable effect on reduction of NO_x emission during coal combustion.
基金Supported by the School Management Project of Xi an Polytechnic University(09XG38)
文摘The new rural cooperative medical system has achieved periodical achievements since its establishment.Nevertheless,there are many factors hampering the development of the new system,such as the high cost,the difficulties in fund procurement,the lack of management,the narrow coverage of benefit,the ineffective constraint to the designated medical institutions,the high fund balance rate,and the poor medical facilities and services in rural areas.Countermeasures are put forward to solve these problems,including improving the system design,expanding the coverage of the system,expanding the fund sources,reducing the financing costs,strengthening the fund supervision,enhancing the supervision of designated medical institutions,and improving the capacity of health services in rural areas.
基金financially supported by the National Key Research and Development Program of China (2018YFD1000107)the open research project of the "Cross-Cooperative Team" of the Germplasm Bank of Wild Species to A.Z.
文摘The T2/RNase gene family is widespread in eukaryotes,and particular members of this family play critical roles in the gametophytic self-incompatibility(GSI) system in plants.Wild diploid strawberry(Fragaria)species have diversified their sexual systems via self-incompatible and self-compatible traits,yet how these traits evolved in Fragaria remains elusive.By integrating the published and de novo assembled genomes and the newly generated RNA-seq data,members of the RNase T2 gene family were systematically identified in six Fragaria species,including three self-incompatible species(Fragaria nipponica,Fragaria nubicola,and Fragaria viridis) and three self-compatible species(Fragaria nilgerrensis,Fragaria vesca,and Fragaria iinumae).In total,115 RNase T2 genes were identified in the six Fragaria genomes and can be classified into three classes(Ⅰ-Ⅲ) according to phylogenetic analysis.The identified RNase T2 genes could be divided into 22 homologous gene sets according to amino acid sequence similarity and phylogenetic and syntenic relationships.We found that extensive gene loss and pseudogenization coupled with small-scale duplications mainly accounted for variations in the RNase T2 gene numbers in Fragaria.Multiple copies of homologous genes were mainly generated from tandem and segmental duplication events.Furthermore,we newly identified five S-RNase genes in three self-incompatible Fragaria genomes,including two in F.nipponica,two in F.viridis,and one in F.nubicola,which fit for typical features of a pistil determinant,including highly pistil-specific expression,highly polymorphic proteins and alkaline isoelectric point(pI),while no S-RNase genes were found in all three selfcompatible Fragaria species.Surprisingly,these T2/S-RNase genes contain at least one large intron(>10 kb).This study revealed that the rapid evolution of T2/S-RNase genes within the Fragaria genus could be associated with its sexual mode,and repeated evolution of the self-compatible traits in Fragaria was convergent via losses of S-RNase.
基金supported by the Postdoctoral Science Foundation of China(Grant No.2020TQ0028)the National Natural Science Foundation of China(No.62173016)Beijing Natural Science Foundation,PRChina(No.4202038)。
文摘The region coverage control problem of multiple stratospheric airships system is firstly addressed in this paper.Towards it,we propose a two-layer control framework with the artificial potential field(APF)-based region coverage control law and the adaptive tracking control law.The APF-based region coverage control law ensures the coverage task is achieved until every single stratospheric airship ends up performing station keeping where near the respective global minimum point,in which an innovative solution to the local minimum problem is put forward.The adaptive tracking control law is designed to realize motion control using tracking the desired velocity and angular velocity given by coverage control law,with the consideration of several practical control problems as unknown individual differences and external disturbances.To save resources,the combined self-/event-triggered mechanism designed therein significantly reduces the times of state information transmission and control law calculation.The effectiveness of the proposed control framework is verified through simulations.
文摘Metabolic rewiring underlies the effector functions of macrophages1-3,but the mechanisms involved remain incompletely defined.Here,using unbiased metabolomics and stable isotope-assisted tracing,we show that an inflammatory aspartate argininosuccinate shunt is induced following lipopolysaccharide stimulation.The shunt,supported by increased argininosuccinate synthase(ASS1)expression,also leads to increased cytosolic fumarate levels and fumarate-mediated protein succination.Pharmacological inhibition and genetic ablation of the tricarboxylic acid cycle enzyme fumarate hydratase(FH)further increases intracellular fumarate levels.
基金support by the National Natural Science Foundation of China(Grant Nos.52108376 and 51908371)China Postdoctoral Science Foundation(Grant No.2022T150436).
文摘This paper presents a simplified elastic continuum method for calculating the restraint effect of isolation piles on tunneling-induced vertical ground displacement,which can consider not only the relative sliding of the pile‒soil interface but also the pile rowesoil interaction.The proposed method is verified by comparisons with existing theoretical methods,including the boundary element method and the elastic foundation method.The results reveal the restraining mechanism of the isolation piles on vertical ground displacements due to tunneling,i.e.the positive and negative restraint effects exerted by the isolation piles jointly drive the ground vertical displacement along the depth direction from the original tunneling-induced nonlinear variation situation to a relatively uniform situation.The results also indicate that the stiffness of the pile‒soil interface,including the pile shaft‒surrounding soil interface and pile tip-supporting soil interface,describes the strength of the pile‒soil interaction.The pile rows can confine the vertical ground displacement caused by the tunnel excavation to the inner side of the isolation piles and effectively prevent the vertical ground displacement from expanding further toward the outer side of the isolation piles.
基金supported by the National natural Science Foundation of China [grant numbers 12172198, 11272189 and 52078283]Youth Innovation Technology Project of Higher School in Shandong Province [grant number 2019KJG015]。
文摘Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experimental measurement and numerical simulation techniques. Comprehensive parametric studies are carried out to discuss the influence of end connection types, temperature, impact velocity,impact mass and span-to-depth ratio(SDR) on the dynamic response of the beams. The characteristics of deformation, internal force and energy distribution about the restrained beams and its joints are investigated. A temperature dependent criterion for evaluating the frame joint performance is proposed to measure the degree of performance degradation and impact resistance of the joint. The dynamic displacement amplification factor in different temperature environments are proposed for the different beam end constraint types and SDRs. Results of the experimental and numerical analysis show that the welded connection(WC) of three typical joint types is the strongest, and the extended endplate connection(EEC) is the weakest in terms of the impact resistance performance. With regard to the failure mode of the joint, the failure positions of the WC and the welded-bolted connection are located in the inner web of the column. Meanwhile, the EEC is located in the connection position between the beam and the endplate. Three different internal force stages and two obvious critical temperature boundaries of the restrained beams emerge with the increase in temperature, and they have significant characteristics in terms of deformation trend, internal force transfer and energy distribution. During the impact, a phenomenon known as “compression arch action” develops into “catenary action” with the increase in deflection in the frame beam mechanism.