鸣禽高级发声中枢(high vocal center,HVC)至弓状皮质栎核(robust nucleus of the arcopallium,RA)的突触传递是鸣唱运动通路中的关键部分。本文运用在体场电位电生理记录的方法,研究了成年雄性斑胸草雀(Taeniopygia guttata)HVC-RA突...鸣禽高级发声中枢(high vocal center,HVC)至弓状皮质栎核(robust nucleus of the arcopallium,RA)的突触传递是鸣唱运动通路中的关键部分。本文运用在体场电位电生理记录的方法,研究了成年雄性斑胸草雀(Taeniopygia guttata)HVC-RA突触的电生理特性。实验结果显示,刺激HVC,在RA内所记录到的诱发场电位幅度较小。配对脉冲检测发现,HVC-RA突触传递具有明显的配对脉冲易化特性。当以强直刺激作用于HVC,RA内诱发场电位随即显著减小,并在15min内逐渐恢复,表明HVC-RA突触传递在强直刺激过后出现了短时抑制。该通路的突触传递特性可能与其在发声控制中的作用有关。以上的实验结果为进一步研究发声运动过程中的突触可塑性提供了资料。展开更多
运用全细胞膜片钳记录法,在离体细胞水平研究了去势引起的雄激素水平降低对HVC不同神经元电生理特性的影响.研究结果显示:去势组与对照组相比,投射神经元HVCRA膜时间常数明显下降(df=38,P<0.01),输入电阻降低(df=35,P<0.01),动作...运用全细胞膜片钳记录法,在离体细胞水平研究了去势引起的雄激素水平降低对HVC不同神经元电生理特性的影响.研究结果显示:去势组与对照组相比,投射神经元HVCRA膜时间常数明显下降(df=38,P<0.01),输入电阻降低(df=35,P<0.01),动作电位后超极化幅值(df=43,P<0.05)及达到峰值时间(df=43,P<0.01)延长.投射神经元HVCx的相关指标变化情况与HVCRA神经元大致类似,差异表现在去势后投射神经元HVCX动作电位延时显著增加(df=55,P<0.01),显示雄激素可以提高2类投射神经元的兴奋性.研究结果表明:雄激素可以在一定程度上提高HVC神经元的兴奋性,雄激素可通过增强HVC对发声运动通路(Vocal Motor Pathway,VMP)的控制,抑制前端脑通路(Anterior Forebrain Pathway,AFP)来实现维持鸣曲的稳定.展开更多
Blended teaching has caught many researchers’attention recently.This paper,taking higher vocational college(HVC)English teaching for example,first explores some theories on evaluating blended teaching,analyzes existi...Blended teaching has caught many researchers’attention recently.This paper,taking higher vocational college(HVC)English teaching for example,first explores some theories on evaluating blended teaching,analyzes existing evaluation frameworks and puts forward ways to evaluate HVC English blended teaching.展开更多
Blended learning has caught many researchers’attention recently.This paper,taking HVC English teaching for example,first explores the problems in the current blended learning and then puts forward several correspondi...Blended learning has caught many researchers’attention recently.This paper,taking HVC English teaching for example,first explores the problems in the current blended learning and then puts forward several corresponding strategies.展开更多
This study aims to develop an accurate calculation model of transmission torque and load-bearing capacity for hydro-viscous clutches(HVC)used in high-power vehicles,which is important to investigate the step-less spee...This study aims to develop an accurate calculation model of transmission torque and load-bearing capacity for hydro-viscous clutches(HVC)used in high-power vehicles,which is important to investigate the step-less speed regulation characteristics in a fan drive system.However,most of the existing models ignore the distribution differences of groove area along the radial direction,which may lead to significant deviations in calculating the mechanical property of friction pairs related to operating conditions and the engagement process.To fill this gap,a new calculation model for bearing capacity and frictional torque of friction pairs with different oil grooves is proposed,in which the traditional fixed contact area ratio coefficient for oil groove measurement is replaced by a more precise discrete micro-ring area ratio(DMAR)integration method.Then,a 32-degree-of-freedoms dynamic model of HVC at a fan drive system is established for the prediction of dynamic responses during speed regulation.Results show that friction pairs with different oil grooves have a direct influence on frictional torque and bearing capacity through the change of DMAR along the radial direction.The friction pairs with different groove structures have oscillation phenomena at the engagement steady-state boundary.Furthermore,a step-less speed regulation experimental setup is established to verify the correctness of the proposed model.It is demonstrated that the axial engagement force and the speed regulation curve predicted by the proposed method are in good agreement with the experimental data.The results could effectively predict the engagement dynamic characteristics.The numerical relationship among the structure parameters,the mechanical properties of friction pairs,and the speed regulation characteristics of the system are established through the proposed model,which lays a theoretical foundation for the structure design of friction plates and optimization of step-less speed regulation performance.展开更多
Against the backdrop of the digital transformation of vocational education,informal digital learning of foreign language(hereinafter referred to as IDLFL)is an emerging learning model with significant potential for en...Against the backdrop of the digital transformation of vocational education,informal digital learning of foreign language(hereinafter referred to as IDLFL)is an emerging learning model with significant potential for enabling individualized and autonomous learning and improving workplace English proficiency among Higher Vocational Colleges(hereinafter referred to as HVC)students.This study explores how Chinese foreign language teachers in HVC perceive and understand HVC students’IDLFL.Primary data are collected through questionnaires and interviews,and qualitative analysis is conducted based on grounded theory to reveal effective ways to improve the foreign language learning outcomes of HVC students through IDLFL and the corresponding strategies that HVC language teachers should adopt.However,this study also emphasizes the need to be wary of overstating the impact and role of IDLFL in teaching practice.展开更多
Three Ti-6Al-4V alloy powders with median diameters of 103, 66 and 44 pm, respectively, were pressed by high-velocity compaction （HVC） technology and then sintered in vacuum. The effects of particle sizes on forming...Three Ti-6Al-4V alloy powders with median diameters of 103, 66 and 44 pm, respectively, were pressed by high-velocity compaction （HVC） technology and then sintered in vacuum. The effects of particle sizes on forming as well as properties of sintered samples were investigated. The results show that fine powders are more difficult to press than coarse powders and its compact density is lower too. But the sintered density of fine powders is obviously higher than that of coarse powders. Compared with the powders with 103 and 66 ~un in diameter, the green density with 44 ~rn diameter powders is lower, which is 85.1% of theoretical density （TD） at an impact energy of 913 J. After sintering at 1300 ~C for 2,5 h, the sintered density of the compacts with 44 pm diameter powders is the highest, and reaches 98.2% of TD. Moreover, the sintered sample with 44 pan in diameter has the highest hardness and compressive strength, which are HV 354 and 1265 MPa, respectively.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.30370197,30570232)the Natural Science Foundation of Guangdong Province(No.05005910).
文摘鸣禽高级发声中枢(high vocal center,HVC)至弓状皮质栎核(robust nucleus of the arcopallium,RA)的突触传递是鸣唱运动通路中的关键部分。本文运用在体场电位电生理记录的方法,研究了成年雄性斑胸草雀(Taeniopygia guttata)HVC-RA突触的电生理特性。实验结果显示,刺激HVC,在RA内所记录到的诱发场电位幅度较小。配对脉冲检测发现,HVC-RA突触传递具有明显的配对脉冲易化特性。当以强直刺激作用于HVC,RA内诱发场电位随即显著减小,并在15min内逐渐恢复,表明HVC-RA突触传递在强直刺激过后出现了短时抑制。该通路的突触传递特性可能与其在发声控制中的作用有关。以上的实验结果为进一步研究发声运动过程中的突触可塑性提供了资料。
文摘运用全细胞膜片钳记录法,在离体细胞水平研究了去势引起的雄激素水平降低对HVC不同神经元电生理特性的影响.研究结果显示:去势组与对照组相比,投射神经元HVCRA膜时间常数明显下降(df=38,P<0.01),输入电阻降低(df=35,P<0.01),动作电位后超极化幅值(df=43,P<0.05)及达到峰值时间(df=43,P<0.01)延长.投射神经元HVCx的相关指标变化情况与HVCRA神经元大致类似,差异表现在去势后投射神经元HVCX动作电位延时显著增加(df=55,P<0.01),显示雄激素可以提高2类投射神经元的兴奋性.研究结果表明:雄激素可以在一定程度上提高HVC神经元的兴奋性,雄激素可通过增强HVC对发声运动通路(Vocal Motor Pathway,VMP)的控制,抑制前端脑通路(Anterior Forebrain Pathway,AFP)来实现维持鸣曲的稳定.
文摘Blended teaching has caught many researchers’attention recently.This paper,taking higher vocational college(HVC)English teaching for example,first explores some theories on evaluating blended teaching,analyzes existing evaluation frameworks and puts forward ways to evaluate HVC English blended teaching.
文摘Blended learning has caught many researchers’attention recently.This paper,taking HVC English teaching for example,first explores the problems in the current blended learning and then puts forward several corresponding strategies.
基金Supported by the National Natural Science Foundation of China(Grant Nos.52475089,52035002)National Key Research and Development Program of China(Grant No.2021YFB2011400)the Chongqing Natural Science Foundation(Grant No.CSTB2022NSCQ-MSX1243).
文摘This study aims to develop an accurate calculation model of transmission torque and load-bearing capacity for hydro-viscous clutches(HVC)used in high-power vehicles,which is important to investigate the step-less speed regulation characteristics in a fan drive system.However,most of the existing models ignore the distribution differences of groove area along the radial direction,which may lead to significant deviations in calculating the mechanical property of friction pairs related to operating conditions and the engagement process.To fill this gap,a new calculation model for bearing capacity and frictional torque of friction pairs with different oil grooves is proposed,in which the traditional fixed contact area ratio coefficient for oil groove measurement is replaced by a more precise discrete micro-ring area ratio(DMAR)integration method.Then,a 32-degree-of-freedoms dynamic model of HVC at a fan drive system is established for the prediction of dynamic responses during speed regulation.Results show that friction pairs with different oil grooves have a direct influence on frictional torque and bearing capacity through the change of DMAR along the radial direction.The friction pairs with different groove structures have oscillation phenomena at the engagement steady-state boundary.Furthermore,a step-less speed regulation experimental setup is established to verify the correctness of the proposed model.It is demonstrated that the axial engagement force and the speed regulation curve predicted by the proposed method are in good agreement with the experimental data.The results could effectively predict the engagement dynamic characteristics.The numerical relationship among the structure parameters,the mechanical properties of friction pairs,and the speed regulation characteristics of the system are established through the proposed model,which lays a theoretical foundation for the structure design of friction plates and optimization of step-less speed regulation performance.
文摘Against the backdrop of the digital transformation of vocational education,informal digital learning of foreign language(hereinafter referred to as IDLFL)is an emerging learning model with significant potential for enabling individualized and autonomous learning and improving workplace English proficiency among Higher Vocational Colleges(hereinafter referred to as HVC)students.This study explores how Chinese foreign language teachers in HVC perceive and understand HVC students’IDLFL.Primary data are collected through questionnaires and interviews,and qualitative analysis is conducted based on grounded theory to reveal effective ways to improve the foreign language learning outcomes of HVC students through IDLFL and the corresponding strategies that HVC language teachers should adopt.However,this study also emphasizes the need to be wary of overstating the impact and role of IDLFL in teaching practice.
基金Project (51004040) supported by the National Natural Science Foundation of ChinaProject (20110952K) supported by Open Research Fund of State Key Laboratory of Powder Metallurgy of Central South University, China
文摘Three Ti-6Al-4V alloy powders with median diameters of 103, 66 and 44 pm, respectively, were pressed by high-velocity compaction （HVC） technology and then sintered in vacuum. The effects of particle sizes on forming as well as properties of sintered samples were investigated. The results show that fine powders are more difficult to press than coarse powders and its compact density is lower too. But the sintered density of fine powders is obviously higher than that of coarse powders. Compared with the powders with 103 and 66 ~un in diameter, the green density with 44 ~rn diameter powders is lower, which is 85.1% of theoretical density （TD） at an impact energy of 913 J. After sintering at 1300 ~C for 2,5 h, the sintered density of the compacts with 44 pm diameter powders is the highest, and reaches 98.2% of TD. Moreover, the sintered sample with 44 pan in diameter has the highest hardness and compressive strength, which are HV 354 and 1265 MPa, respectively.
