The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive manufacturing.In this paper,with the wire feeding s...The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive manufacturing.In this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial direction.The results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was expanded.When the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting amount.The average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc power.The minimum melting amount was not affected by the wire-torch distance under any current separation ratio tested.When the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch distance.When the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch distance.The effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation ratio.Through this study,the decoupling mechanism and ability of this innovative arc heat source is more clearly.展开更多
To evaluate and select elite Pinus koraiensis parent combinations and offspring families,34 full-sib families were evaluated.Variance analysis of tree height,diameter at breast height and volume showed no significant ...To evaluate and select elite Pinus koraiensis parent combinations and offspring families,34 full-sib families were evaluated.Variance analysis of tree height,diameter at breast height and volume showed no significant differences among each block,the interaction of block,male and female.The family heritability of all traits were high(>0.9).Phenotypic and genotypic coefficients of variance of height,diameter at breast height,and volume showed that the phenotypic coefficient of variation of volume in the same combination was higher than height and diameter at breast height,indicating that volume was the main factor determining excellent single plant selection.The female and male trees with the best general combining ability indicated that the optimal parental hybridization was not necessarily the optimal combination.In addition,the least parents of hybrid offspring performance were always relatively poor and should not be selected as hybrid parents.Additionally,we found there was no significant difference among the effects of female and male parents by random modelling,but there were significant differences by fixed modelling.The most significant effect of female-and male interaction,and the selection of better female or male parents in the test parent group should be efficient as well as the results of significant variation among them by fixed modelling.For the evaluated breeding population of P.koraiensis,the backward selection of excellent parent combinations or forward selection of excellent individuals as progeny should be the major breeding strategies.展开更多
Now the surface settlement induced by shallow buried tunnel to under-traverse highway,mostly adopt the empirical value,3 cm,acquired from Beijing or Shenzhen metro,which is regarded as the controlling standard.But to ...Now the surface settlement induced by shallow buried tunnel to under-traverse highway,mostly adopt the empirical value,3 cm,acquired from Beijing or Shenzhen metro,which is regarded as the controlling standard.But to more project,tunnel under-traverse highway,we must decide the controlling standard flexibly,which should base on the pavement service function and the pavement condition.The thesis,based on the pavement evenness and running comfort ability in the view of completing the pavement service function,supposes the longitudinal pavement settlement cross section as a quadratic parabola,and gets the maximal settlement value in the range of longitudinal pavement influence when the tunnel is under-traverse highway perpendicularly.Then the controlling standard is decided.As Wenxiang Tunnel under-traverse Lianhuo Freeway on Zhengzhou-Xi'an Passenger Dedicated Railway Line for an example,the settlement controlling standard is acquired,and we hope it has an direction and reference value to similar tunnel construction.展开更多
Objective: To investigate the effect of respiratory muscle training combined with conventional rehabilitation therapy on trunk control, balance ability and activities of daily living in stroke patients. Methods: Sixty...Objective: To investigate the effect of respiratory muscle training combined with conventional rehabilitation therapy on trunk control, balance ability and activities of daily living in stroke patients. Methods: Sixty stroke patients were divided into control group and experimental group by random number table, 30 each, and received conventional rehabilitation therapy. Moreover, the experimental group underwent respiratory muscle training (RMT), for four weeks. In each patient, maximal inspiratory pressure (MIP) was measured for the inspiratory muscle strength. Maximal expiratory pressure (MEP) was measured for the expiratory muscle strength. The trunk control was measured using the Trunk Impairment Scale (TIS). The Berg balance scale (BBS) was used to assess the balance function. The modified Barthel index (MBI) was used to evaluate activities of daily living. Results: There were no significant differences in MIP, MEP, TIS, BBS and MBI between the two groups before treatment. The MIP, MEP, TIS, BBS and MBI functions of the control group and the experimental group were improved after treatment, And the functional improvement of the above indicators in the experimental group after treatment was significantly higher than that of the control group. Conclusion: This study proved that RMT improved respiratory muscle strength, trunk control, balance function, and ADL in stroke patients.展开更多
Context, as a main domain for linguistic research, greatly influences the understanding in communication. In English listening, context is one of the factors affecting the listening comprehension. However, it is often...Context, as a main domain for linguistic research, greatly influences the understanding in communication. In English listening, context is one of the factors affecting the listening comprehension. However, it is often neglected and as a result, students' listening can't be improved effectively. In order to improve students English listening comprehension, this thesis introduces the theory of context and the substance of English listening, analyses the roles that context plays in English listening from three factors: context of vocabulary、context of situation and context of cultural. It also introduces how to use the context freely when students are listening.展开更多
For young teachers,the ability to transform teaching materials and the ability to control teaching is a basic teaching regulation and control ability. Through a case teaching of function limits in the mathematics cour...For young teachers,the ability to transform teaching materials and the ability to control teaching is a basic teaching regulation and control ability. Through a case teaching of function limits in the mathematics course,this article studied how to explore deep into the content of textbooks,use the textbooks in a creative and proper manner,help students better understand and master the content of teaching,improve students ’autonomous learning ability,and promote comprehensive improvement of students’ knowledge,ability and caliber.展开更多
Over the years of vigorous development of English language teaching, ELT has been regarded by many as a distinct profession, which will only exist by its practitioners’ developing and perfecting it. As a practitioner...Over the years of vigorous development of English language teaching, ELT has been regarded by many as a distinct profession, which will only exist by its practitioners’ developing and perfecting it. As a practitioner of the profession, an ELT teacher is to possess and acquire technical qualities, a professional understanding and personal qualities consisting in personality, intelligence & aptitude, attitude & motivation, competence in the English language.展开更多
Rock drill-ability anisotropy has significant effects on directional drilling and deviation control. Its evaluation is an important but difficult research subject. Definitions of drill-ability anisotropy and acoustic ...Rock drill-ability anisotropy has significant effects on directional drilling and deviation control. Its evaluation is an important but difficult research subject. Definitions of drill-ability anisotropy and acoustic anisotropy of rock are given in this paper. The acoustic velocities and the drill-ability parameters of several rock samples from the Engineering Center for Chinese Continemal Scientific Drilling （CCSD） are respectively measured with the device for testing the rock drill-ability and the ultrasonic testing system in laboratory, so that their drill-ability anisotropy and acoustic anisotropy are respectively calculated and discussed in detail by using the experimental data. On the basis of these experimental results and calculations, correlations between drill-ability anisotropy and acoustic anisotropy of the rock samples are illustrated through regression analyses. Thus, a mathematical model developed may be used to evaluate the rock drill- ability anisotropy with the acoustic logging or seismic data to a certain extent.展开更多
基金Supported by Youth Program of National Natural Science Foundation of China(Grant No.51905008)Beijing Postdoctoral Research Foundation of China(Grant No.2021-zz-064)+2 种基金Shandong Provincial Major Science and Technology Innovation Project of China(Grant No.2020JMRH0504)Jinan Innovation Team Project of China(Grant No.2021GXRC066)Quancheng Scholars Construction Project of China(Grant No.D03032).
文摘The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive manufacturing.In this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial direction.The results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was expanded.When the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting amount.The average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc power.The minimum melting amount was not affected by the wire-torch distance under any current separation ratio tested.When the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch distance.When the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch distance.The effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation ratio.Through this study,the decoupling mechanism and ability of this innovative arc heat source is more clearly.
基金supported by The National Key Research and Development Program of China(Grant No.2017YFD0600500)。
文摘To evaluate and select elite Pinus koraiensis parent combinations and offspring families,34 full-sib families were evaluated.Variance analysis of tree height,diameter at breast height and volume showed no significant differences among each block,the interaction of block,male and female.The family heritability of all traits were high(>0.9).Phenotypic and genotypic coefficients of variance of height,diameter at breast height,and volume showed that the phenotypic coefficient of variation of volume in the same combination was higher than height and diameter at breast height,indicating that volume was the main factor determining excellent single plant selection.The female and male trees with the best general combining ability indicated that the optimal parental hybridization was not necessarily the optimal combination.In addition,the least parents of hybrid offspring performance were always relatively poor and should not be selected as hybrid parents.Additionally,we found there was no significant difference among the effects of female and male parents by random modelling,but there were significant differences by fixed modelling.The most significant effect of female-and male interaction,and the selection of better female or male parents in the test parent group should be efficient as well as the results of significant variation among them by fixed modelling.For the evaluated breeding population of P.koraiensis,the backward selection of excellent parent combinations or forward selection of excellent individuals as progeny should be the major breeding strategies.
文摘Now the surface settlement induced by shallow buried tunnel to under-traverse highway,mostly adopt the empirical value,3 cm,acquired from Beijing or Shenzhen metro,which is regarded as the controlling standard.But to more project,tunnel under-traverse highway,we must decide the controlling standard flexibly,which should base on the pavement service function and the pavement condition.The thesis,based on the pavement evenness and running comfort ability in the view of completing the pavement service function,supposes the longitudinal pavement settlement cross section as a quadratic parabola,and gets the maximal settlement value in the range of longitudinal pavement influence when the tunnel is under-traverse highway perpendicularly.Then the controlling standard is decided.As Wenxiang Tunnel under-traverse Lianhuo Freeway on Zhengzhou-Xi'an Passenger Dedicated Railway Line for an example,the settlement controlling standard is acquired,and we hope it has an direction and reference value to similar tunnel construction.
文摘Objective: To investigate the effect of respiratory muscle training combined with conventional rehabilitation therapy on trunk control, balance ability and activities of daily living in stroke patients. Methods: Sixty stroke patients were divided into control group and experimental group by random number table, 30 each, and received conventional rehabilitation therapy. Moreover, the experimental group underwent respiratory muscle training (RMT), for four weeks. In each patient, maximal inspiratory pressure (MIP) was measured for the inspiratory muscle strength. Maximal expiratory pressure (MEP) was measured for the expiratory muscle strength. The trunk control was measured using the Trunk Impairment Scale (TIS). The Berg balance scale (BBS) was used to assess the balance function. The modified Barthel index (MBI) was used to evaluate activities of daily living. Results: There were no significant differences in MIP, MEP, TIS, BBS and MBI between the two groups before treatment. The MIP, MEP, TIS, BBS and MBI functions of the control group and the experimental group were improved after treatment, And the functional improvement of the above indicators in the experimental group after treatment was significantly higher than that of the control group. Conclusion: This study proved that RMT improved respiratory muscle strength, trunk control, balance function, and ADL in stroke patients.
文摘Context, as a main domain for linguistic research, greatly influences the understanding in communication. In English listening, context is one of the factors affecting the listening comprehension. However, it is often neglected and as a result, students' listening can't be improved effectively. In order to improve students English listening comprehension, this thesis introduces the theory of context and the substance of English listening, analyses the roles that context plays in English listening from three factors: context of vocabulary、context of situation and context of cultural. It also introduces how to use the context freely when students are listening.
基金Supported by Education Research and Reform Program of Tianjin Agricultural University in 2018"A Practical Study of the Teaching Ability Cultivation of Young Teachers in Colleges and Universities"(2018-B-35).
文摘For young teachers,the ability to transform teaching materials and the ability to control teaching is a basic teaching regulation and control ability. Through a case teaching of function limits in the mathematics course,this article studied how to explore deep into the content of textbooks,use the textbooks in a creative and proper manner,help students better understand and master the content of teaching,improve students ’autonomous learning ability,and promote comprehensive improvement of students’ knowledge,ability and caliber.
文摘Over the years of vigorous development of English language teaching, ELT has been regarded by many as a distinct profession, which will only exist by its practitioners’ developing and perfecting it. As a practitioner of the profession, an ELT teacher is to possess and acquire technical qualities, a professional understanding and personal qualities consisting in personality, intelligence & aptitude, attitude & motivation, competence in the English language.
文摘Rock drill-ability anisotropy has significant effects on directional drilling and deviation control. Its evaluation is an important but difficult research subject. Definitions of drill-ability anisotropy and acoustic anisotropy of rock are given in this paper. The acoustic velocities and the drill-ability parameters of several rock samples from the Engineering Center for Chinese Continemal Scientific Drilling （CCSD） are respectively measured with the device for testing the rock drill-ability and the ultrasonic testing system in laboratory, so that their drill-ability anisotropy and acoustic anisotropy are respectively calculated and discussed in detail by using the experimental data. On the basis of these experimental results and calculations, correlations between drill-ability anisotropy and acoustic anisotropy of the rock samples are illustrated through regression analyses. Thus, a mathematical model developed may be used to evaluate the rock drill- ability anisotropy with the acoustic logging or seismic data to a certain extent.
