Based on the analysis of nonlinear geometric characteristics of the suspension systems and tires, a 3D nonlinear dynamic model of a typical heavy truck is established. The impact factors of dynamic tire loads, includi...Based on the analysis of nonlinear geometric characteristics of the suspension systems and tires, a 3D nonlinear dynamic model of a typical heavy truck is established. The impact factors of dynamic tire loads, including the dynamic load stress factors, and the maximal and the minimal vertical dynamic load factors, are used to evaluate the dynamic interaction between heavy vehicles and roads under the condition of random road surface roughness. Matlab/Simulink is used to simulate the nonlinear dynamic system and calculate the impact factors. The effects of different road surface conditions on the safety of vehicle movement and the durability of parts of a vehicle are analyzed, as well as the effects of different structural parameters and different vehicle speeds on road surfaces. The study results provide both the warning limits of road surface roughness and the limits of corresponding dynamic parameters for the 5-axle heavy truck.展开更多
A marine red tide algae denominated as Heterocapsa circularisquama was cultured under the control factors. And the ecological function of nutrient salts such as nitrogen （mg/L）, phosphorus （rag/L） as well as silic...A marine red tide algae denominated as Heterocapsa circularisquama was cultured under the control factors. And the ecological function of nutrient salts such as nitrogen （mg/L）, phosphorus （rag/L） as well as silicon （rag/L） in different consistency on the population growth of H. circularisquama was investigated. The results showed that overtop or too low consistency of nutrient salts both delayed the population multiplication of the red tide algae, and different nutrient factors as nitrogen, phosphorus and silicon all had significant effects on the population amplification of H.circularisquama （p〈0.01）. The optimal concentration of nitrogen, phosphorus and silicon in the culture medium for the algae propagation and growth were 10 mg/L, 1-5 mg/L and 0 mg/L respectively.展开更多
Dynamic tire forces are the main factor affecting the measurement accuracy of the axle weight of moving vehicle.This paper presents a novel method to reduce the influence of the dynamic tire forces on the weighing acc...Dynamic tire forces are the main factor affecting the measurement accuracy of the axle weight of moving vehicle.This paper presents a novel method to reduce the influence of the dynamic tire forces on the weighing accuracy.On the basis of analyzing the characteristic of the dynamic tire forces,the objective optimization equation is constructed.The optimization algorithm is presented to get the optimal estimations of the objective parameters.According to the estimations of the parameters,the dynamic tire forces are separated from the axle weigh signal.The results of simulation and field experiments prove the effectiveness of the proposed method.展开更多
This survey study investigates some university English language teachers' attitudes to using Communicative Language Teaching (CLT) and their perceptions of the factors that affect their implementation of this appr...This survey study investigates some university English language teachers' attitudes to using Communicative Language Teaching (CLT) and their perceptions of the factors that affect their implementation of this approach in specific contexts. The study confirms that CLT is strongly favoured by these language teachers who, at the same time, encounter certain contextual constraints for practising CLT effectively. Meanwhile it also provides evidence that some newly emerged conditions have created a supportive environment and are conducive to promoting CLT. The study thus also calls for further research to address the identified constraining factors in this regard.展开更多
Coarse roots play a critical role in forest ecosystems and both abiotic and biotic factors affect their spatial distribution.To some extent,coarse root density may reflect the quantity of root biomass and biotic compe...Coarse roots play a critical role in forest ecosystems and both abiotic and biotic factors affect their spatial distribution.To some extent,coarse root density may reflect the quantity of root biomass and biotic competition in forests.However,using traditional methods(e.g.,excavation)to study coarse roots is challenging,because those methods are time-consuming and laborious.Furthermore,these destructive methods cannot be repeated in the same forests.Therefore,the discovery of non-destructive methods for root studies will be very significant.In this study,we used a ground-penetrating radar technique to detect the coarse root density of three habitats(ridge,slope and valley)and the dominant tree species(Castanopsis eyrei and Schima superba)in a subtropical forest.We found that(i)the mean of coarse root density for these three habitats was 88.04roots m–2,with roots being mainly distributed at depths of 0–40 cm.Coarse root densities were lower in deeper soils and in areas far from the trunk.(ii)Coarse root densities differed significantly among the three habitats studied here with slope habitat having the lowest coarse root density.Compared with S.superba,C.eyrei had more roots distributed in deeper soils.Furthermore,coarse roots with a diameter>3 cm occurred more frequently in the valleys,compared with root densities in ridge and slope habitats,and most coarse roots occurred at soil depths of 20–40 cm.(iii)The coarse root density correlated negatively with tree species richness at soil depths of 40–60 cm.The abundances of the dominant species,such as C.eyrei,Cyclobalanopsis glauca,Pinus massoniana,had significant impacts on coarse root density.(iv)The soil depth of 0–40 cm was the"basic distribution layer"for coarse roots since the majority of coarse roots were found in this soil layer with an average root density of 84.18 roots m–2,which had no significant linear relationships with topography,tree species richness,rarefied tree species richness and tree density.Significant relationships between coarse root density and these factors were found at the soil depth of40–60 cm,which was the"potential distribution layer"for coarse root distribution.展开更多
基金The Science and Technology Support Program of Jiangsu Province(No.BE201047)
文摘Based on the analysis of nonlinear geometric characteristics of the suspension systems and tires, a 3D nonlinear dynamic model of a typical heavy truck is established. The impact factors of dynamic tire loads, including the dynamic load stress factors, and the maximal and the minimal vertical dynamic load factors, are used to evaluate the dynamic interaction between heavy vehicles and roads under the condition of random road surface roughness. Matlab/Simulink is used to simulate the nonlinear dynamic system and calculate the impact factors. The effects of different road surface conditions on the safety of vehicle movement and the durability of parts of a vehicle are analyzed, as well as the effects of different structural parameters and different vehicle speeds on road surfaces. The study results provide both the warning limits of road surface roughness and the limits of corresponding dynamic parameters for the 5-axle heavy truck.
文摘A marine red tide algae denominated as Heterocapsa circularisquama was cultured under the control factors. And the ecological function of nutrient salts such as nitrogen （mg/L）, phosphorus （rag/L） as well as silicon （rag/L） in different consistency on the population growth of H. circularisquama was investigated. The results showed that overtop or too low consistency of nutrient salts both delayed the population multiplication of the red tide algae, and different nutrient factors as nitrogen, phosphorus and silicon all had significant effects on the population amplification of H.circularisquama （p〈0.01）. The optimal concentration of nitrogen, phosphorus and silicon in the culture medium for the algae propagation and growth were 10 mg/L, 1-5 mg/L and 0 mg/L respectively.
文摘Dynamic tire forces are the main factor affecting the measurement accuracy of the axle weight of moving vehicle.This paper presents a novel method to reduce the influence of the dynamic tire forces on the weighing accuracy.On the basis of analyzing the characteristic of the dynamic tire forces,the objective optimization equation is constructed.The optimization algorithm is presented to get the optimal estimations of the objective parameters.According to the estimations of the parameters,the dynamic tire forces are separated from the axle weigh signal.The results of simulation and field experiments prove the effectiveness of the proposed method.
文摘This survey study investigates some university English language teachers' attitudes to using Communicative Language Teaching (CLT) and their perceptions of the factors that affect their implementation of this approach in specific contexts. The study confirms that CLT is strongly favoured by these language teachers who, at the same time, encounter certain contextual constraints for practising CLT effectively. Meanwhile it also provides evidence that some newly emerged conditions have created a supportive environment and are conducive to promoting CLT. The study thus also calls for further research to address the identified constraining factors in this regard.
基金supported by the National Natural Science Foundation of China(31170457,30710103907)
文摘Coarse roots play a critical role in forest ecosystems and both abiotic and biotic factors affect their spatial distribution.To some extent,coarse root density may reflect the quantity of root biomass and biotic competition in forests.However,using traditional methods(e.g.,excavation)to study coarse roots is challenging,because those methods are time-consuming and laborious.Furthermore,these destructive methods cannot be repeated in the same forests.Therefore,the discovery of non-destructive methods for root studies will be very significant.In this study,we used a ground-penetrating radar technique to detect the coarse root density of three habitats(ridge,slope and valley)and the dominant tree species(Castanopsis eyrei and Schima superba)in a subtropical forest.We found that(i)the mean of coarse root density for these three habitats was 88.04roots m–2,with roots being mainly distributed at depths of 0–40 cm.Coarse root densities were lower in deeper soils and in areas far from the trunk.(ii)Coarse root densities differed significantly among the three habitats studied here with slope habitat having the lowest coarse root density.Compared with S.superba,C.eyrei had more roots distributed in deeper soils.Furthermore,coarse roots with a diameter>3 cm occurred more frequently in the valleys,compared with root densities in ridge and slope habitats,and most coarse roots occurred at soil depths of 20–40 cm.(iii)The coarse root density correlated negatively with tree species richness at soil depths of 40–60 cm.The abundances of the dominant species,such as C.eyrei,Cyclobalanopsis glauca,Pinus massoniana,had significant impacts on coarse root density.(iv)The soil depth of 0–40 cm was the"basic distribution layer"for coarse roots since the majority of coarse roots were found in this soil layer with an average root density of 84.18 roots m–2,which had no significant linear relationships with topography,tree species richness,rarefied tree species richness and tree density.Significant relationships between coarse root density and these factors were found at the soil depth of40–60 cm,which was the"potential distribution layer"for coarse root distribution.
