A study was conducted to detect the effect of water extracts from different parts such as root, bark, branch and leaf, of adult larch, Larix gmelini, trees on growth of Manchurian walnut, Juglans mandshudca, seedlings...A study was conducted to detect the effect of water extracts from different parts such as root, bark, branch and leaf, of adult larch, Larix gmelini, trees on growth of Manchurian walnut, Juglans mandshudca, seedlings and the allelopathy between the two tree species. Four concentrations （100 g. kg i, 50 g. kg^-1, 25 g. kg^-1 and 12.5 g. kg^-1） were prepared for each kind of extracts. Result showed that the water extracts with low and moderate concentrations accelerated the growth of collar diameter and increased biomass and root/shoot ratio of walnut seedlings. The water extracts from branches and barks with low and moderate concentrations accelerated the height growth of the seedlings, while those from leaves and roots slightly decreased the height growth of seedlings. The fact that application of water extracts of larch improved the growth of Manchurian walnut attributes possibly to the allelopathy between the two tree species.展开更多
Based on the structural characteristic of metal drill collar for induction logging while drilling, we have given the analytical formulae of lengthways fields Ez and Hz when the tool is located in a fan-ring shaped slo...Based on the structural characteristic of metal drill collar for induction logging while drilling, we have given the analytical formulae of lengthways fields Ez and Hz when the tool is located in a fan-ring shaped slot of drill collar by the boundary conditions of electromagnetic field, and derived the other components of electromagnetic field in and out the fan-ring slot from Ez and Hz. In the other intervals of formation, where the drill collar is a solid cylinder, the analytical formulae of field are educed through the method of variable coefficient. The total analytical solutions of field in whole space have been obtained. With the help of the analytical formulae, we have also given numerical examples and analyzed the distributive characteristic of electromagnetic field. From the computational results we find that the secondary scattering field Hz is in a linear relation with the conductivity of stratum. The characteristic of field is very useful for induction logging while drilling, which can be used to measure and analyze the logging responses of the stratum conductivity. This paper sets up a theoretical foundation for us to study the distrbutions of field and to direct the design of logging instruments.展开更多
Fabrics of different thickness were selected and made into notch lapels in the experiment. The variation between the outside and inside lapel patterns after the lapel being folded was observed and measured. Besides,ma...Fabrics of different thickness were selected and made into notch lapels in the experiment. The variation between the outside and inside lapel patterns after the lapel being folded was observed and measured. Besides,many factors leading to the variation were analyzed. Then the relation between fold angle and fabric thickness,and the variation of fabric thickness were obtained. The experimental results prove that the biggest horizontal variation between the outside lapel and inside lapel is at the breast line,and when the measuring point is above (or below) the breast line level,the farther it is away from the level,the smaller the variation becomes. In addition,conclusions can be drawn that the thicker the fabric is,the bigger the curve variation will be,and there is a certain mathematic relation between them.展开更多
The relation between lining collar and face collar in the collar pattern designed by experiments and theoretical calculation is elucidated. In spite of the same constructions, the collar's shape and the fabric'...The relation between lining collar and face collar in the collar pattern designed by experiments and theoretical calculation is elucidated. In spite of the same constructions, the collar's shape and the fabric's thickness influence on the pattern of lining collar and the face collar, especially on the back center of the Iining and the two collar angles. The thicker the fabric, the more, with a proportional relation, the total variation. It is supposed that this work has made some contribution to the collar pattern design.展开更多
Local scour around bridge abutments is a widespread problem that can result in structural failure. Collars can be used as a countermeasure to reduce the scour depth. In this study, the temporal scour development aroun...Local scour around bridge abutments is a widespread problem that can result in structural failure. Collars can be used as a countermeasure to reduce the scour depth. In this study, the temporal scour development around a wing-wall abutment was investigated with and without collars. The tests were carried out under clear-water conditions for different abutment lengths, with collars of different sizes placed at the bed level. When no collar was used in the experiments, 70% of the maximum scour depth occurred in less than 2 h. However, when a collar with a width greater than the length of the abutment was used, no scour was observed for up to 200 min from the beginning of the experiments. The results show that an increase in the collar width not only led to a lag time for the onset of scouring but also reduced the maximum scour depth. Moreover, an increased collar width led to a better performance in mitigating scouring around smaller abutments. Generally, the scour depth decreased by 9%-37% with different collar widths.展开更多
基金This paper was supported by National Natural Science Foundation of China （No. 30400341） and Heilongjiang Provincial Science Foundation （No. C0320）Acknowledgement I thank Dr. YAN Xiu-feng for his help and guidance.
文摘A study was conducted to detect the effect of water extracts from different parts such as root, bark, branch and leaf, of adult larch, Larix gmelini, trees on growth of Manchurian walnut, Juglans mandshudca, seedlings and the allelopathy between the two tree species. Four concentrations （100 g. kg i, 50 g. kg^-1, 25 g. kg^-1 and 12.5 g. kg^-1） were prepared for each kind of extracts. Result showed that the water extracts with low and moderate concentrations accelerated the growth of collar diameter and increased biomass and root/shoot ratio of walnut seedlings. The water extracts from branches and barks with low and moderate concentrations accelerated the height growth of the seedlings, while those from leaves and roots slightly decreased the height growth of seedlings. The fact that application of water extracts of larch improved the growth of Manchurian walnut attributes possibly to the allelopathy between the two tree species.
基金Supported by the National Natural Science Foundation of China(Grant No.10705049)the Beijing Natural Science Foundation(Grant No.1083011)Fund-ing Project for Academic Human Resources Development in Institutions of Higher Learning[PHR(IHLB)]
文摘Based on the structural characteristic of metal drill collar for induction logging while drilling, we have given the analytical formulae of lengthways fields Ez and Hz when the tool is located in a fan-ring shaped slot of drill collar by the boundary conditions of electromagnetic field, and derived the other components of electromagnetic field in and out the fan-ring slot from Ez and Hz. In the other intervals of formation, where the drill collar is a solid cylinder, the analytical formulae of field are educed through the method of variable coefficient. The total analytical solutions of field in whole space have been obtained. With the help of the analytical formulae, we have also given numerical examples and analyzed the distributive characteristic of electromagnetic field. From the computational results we find that the secondary scattering field Hz is in a linear relation with the conductivity of stratum. The characteristic of field is very useful for induction logging while drilling, which can be used to measure and analyze the logging responses of the stratum conductivity. This paper sets up a theoretical foundation for us to study the distrbutions of field and to direct the design of logging instruments.
文摘Fabrics of different thickness were selected and made into notch lapels in the experiment. The variation between the outside and inside lapel patterns after the lapel being folded was observed and measured. Besides,many factors leading to the variation were analyzed. Then the relation between fold angle and fabric thickness,and the variation of fabric thickness were obtained. The experimental results prove that the biggest horizontal variation between the outside lapel and inside lapel is at the breast line,and when the measuring point is above (or below) the breast line level,the farther it is away from the level,the smaller the variation becomes. In addition,conclusions can be drawn that the thicker the fabric is,the bigger the curve variation will be,and there is a certain mathematic relation between them.
文摘The relation between lining collar and face collar in the collar pattern designed by experiments and theoretical calculation is elucidated. In spite of the same constructions, the collar's shape and the fabric's thickness influence on the pattern of lining collar and the face collar, especially on the back center of the Iining and the two collar angles. The thicker the fabric, the more, with a proportional relation, the total variation. It is supposed that this work has made some contribution to the collar pattern design.
文摘Local scour around bridge abutments is a widespread problem that can result in structural failure. Collars can be used as a countermeasure to reduce the scour depth. In this study, the temporal scour development around a wing-wall abutment was investigated with and without collars. The tests were carried out under clear-water conditions for different abutment lengths, with collars of different sizes placed at the bed level. When no collar was used in the experiments, 70% of the maximum scour depth occurred in less than 2 h. However, when a collar with a width greater than the length of the abutment was used, no scour was observed for up to 200 min from the beginning of the experiments. The results show that an increase in the collar width not only led to a lag time for the onset of scouring but also reduced the maximum scour depth. Moreover, an increased collar width led to a better performance in mitigating scouring around smaller abutments. Generally, the scour depth decreased by 9%-37% with different collar widths.
