The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is pr...The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing bendingmode.Accurate prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control law.Instead of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is developed.An accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is proposed.Firstly,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the model.Based on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of themodel.Then combinedwith the variable stiffnessmethod,the critical flutter point of the model is obtained.This method is applied to the BFF calculation of a flyingwing model.The calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran software.Finally,the method is used to analyze the influence factors of BFF.The analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.展开更多
【目的】探究欧李Dof(DNA-binding with one zinc finger)锌指蛋白在非生物胁迫条件下的功能,为ChDof基因的研究与利用奠定基础。【方法】基于欧李全基因组和转录组数据对Dof基因家族进行鉴定,并利用实时定量PCR分析Dof基因在非生物胁...【目的】探究欧李Dof(DNA-binding with one zinc finger)锌指蛋白在非生物胁迫条件下的功能,为ChDof基因的研究与利用奠定基础。【方法】基于欧李全基因组和转录组数据对Dof基因家族进行鉴定,并利用实时定量PCR分析Dof基因在非生物胁迫下的表达情况。【结果】欧李共有23个Dof基因家族成员,其编码区CDS序列长度为226~515 bp,相对分子质量为24227.52~55368.21,理论等电点为4.78~9.36,且其在欧李的8条染色体上都有分布。在构建欧李和拟南芥的系统进化树中发现,欧李共分为9个亚组,同一亚族成员中的基因结构和蛋白保守基序均具有较高的相似性,且欧李Dof基因家族成员主要分布在D1亚组中。在对其亚细胞定位时发现,绝大多数ChDof基因主要分布于细胞核中。对欧李Dof家族成员启动子区域顺式调控元件的预测结果表明,其启动子区存在着至少1个激素调节及逆境胁迫反应元件。qRT-PCR分析结果表明,绝大多数的ChDof基因在盐、高温和低温胁迫下的表达量均上调,而ChDof11、ChDof12、ChDof17基因在盐、渗透(PEG)、高温和低温4种胁迫下的表达量均上升,ChDof03基因对高盐胁迫的反应最敏感,ChDof01基因对低温胁迫的响应最敏感,ChDof11基因在渗透、高温和低温胁迫下的表达量均有极显著的提高,而ChDof7和ChDof08基因在4种胁迫诱导下的表达量均降低。【结论】共鉴定出23个Dof家族成员,欧李ChDof11、ChDof12、ChDof17这3个基因在逆境胁迫中均有控制功能,ChDof7和ChDof08这2个基因则在逆境胁迫中均起负调节作用。Dof基因在欧李对逆境胁迫的响应中发挥着重要作用。展开更多
阐述DNA-binding with one finger(Dof)转录因子在作物中应答极端温度、干旱和盐胁迫等逆境的分子机制及其改良农艺性状的作用;介绍Dof转录因子在作物中响应逆境的信号感知方式和信号转导途径,分析其基因表达调控过程的调控机理以及对...阐述DNA-binding with one finger(Dof)转录因子在作物中应答极端温度、干旱和盐胁迫等逆境的分子机制及其改良农艺性状的作用;介绍Dof转录因子在作物中响应逆境的信号感知方式和信号转导途径,分析其基因表达调控过程的调控机理以及对胁迫耐受力与重要次生代谢产物(RFOs等)等积累的影响。同时从多信号网络调控机制以及全球气候变化对作物可持续和高质量生产的需求角度,对进一步研究和利用Dof转录因子进行作物生物育种的前景和方向作展望。展开更多
3Do F VR是VR视频的一种代表性形态,也是目前虚拟现实领域普遍应用的形式。图像质量是一项会影响用户真实沉浸视觉感受的VR视频QoE的重要指标。目前国内外暂未形成VR视频领域图像质量主观评价的标准方法,为此,本文研究提出了一套3Do F V...3Do F VR是VR视频的一种代表性形态,也是目前虚拟现实领域普遍应用的形式。图像质量是一项会影响用户真实沉浸视觉感受的VR视频QoE的重要指标。目前国内外暂未形成VR视频领域图像质量主观评价的标准方法,为此,本文研究提出了一套3Do F VR视频图像质量主观评价方法。文章首先对VR视频主观评价的挑战、国内外进展进行分析调研,随后着重阐述了3Do F VR视频主观评价前期准备研究、主观评价量表设计、主观评价打分方法改进、实验序列制作等环节,最后进行了3DoF VR视频图像质量主观评价实验,并对实验数据进行了分析和总结。展开更多
基金This work was supported by the National Natural Science Foundation of China(No.11872212)and a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘The reduced weight and improved efficiency of modern aeronautical structures result in a decreasing separation of frequency ranges of rigid and elastic modes.Particularly,a high-aspect-ratio flexible flying wing is prone to body freedomflutter(BFF),which is a result of coupling of the rigid body short-periodmodewith 1st wing bendingmode.Accurate prediction of the BFF characteristics is helpful to reflect the attitude changes of the vehicle intuitively and design the active flutter suppression control law.Instead of using the rigid body mode,this work simulates the rigid bodymotion of the model by using the six-degree-of-freedom(6DOF)equation.A dynamicmesh generation strategy particularly suitable for BFF simulation of free flying aircraft is developed.An accurate Computational Fluid Dynamics/Computational Structural Dynamics/six-degree-of-freedom equation(CFD/CSD/6DOF)-based BFF prediction method is proposed.Firstly,the time-domain CFD/CSD method is used to calculate the static equilibrium state of the model.Based on this state,the CFD/CSD/6DOF equation is solved in time domain to evaluate the structural response of themodel.Then combinedwith the variable stiffnessmethod,the critical flutter point of the model is obtained.This method is applied to the BFF calculation of a flyingwing model.The calculation results of the BFF characteristics of the model agree well with those fromthe modalmethod andNastran software.Finally,the method is used to analyze the influence factors of BFF.The analysis results show that the flutter speed can be improved by either releasing plunge constraint or moving the center ofmass forward or increasing the pitch inertia.
文摘【目的】探究欧李Dof(DNA-binding with one zinc finger)锌指蛋白在非生物胁迫条件下的功能,为ChDof基因的研究与利用奠定基础。【方法】基于欧李全基因组和转录组数据对Dof基因家族进行鉴定,并利用实时定量PCR分析Dof基因在非生物胁迫下的表达情况。【结果】欧李共有23个Dof基因家族成员,其编码区CDS序列长度为226~515 bp,相对分子质量为24227.52~55368.21,理论等电点为4.78~9.36,且其在欧李的8条染色体上都有分布。在构建欧李和拟南芥的系统进化树中发现,欧李共分为9个亚组,同一亚族成员中的基因结构和蛋白保守基序均具有较高的相似性,且欧李Dof基因家族成员主要分布在D1亚组中。在对其亚细胞定位时发现,绝大多数ChDof基因主要分布于细胞核中。对欧李Dof家族成员启动子区域顺式调控元件的预测结果表明,其启动子区存在着至少1个激素调节及逆境胁迫反应元件。qRT-PCR分析结果表明,绝大多数的ChDof基因在盐、高温和低温胁迫下的表达量均上调,而ChDof11、ChDof12、ChDof17基因在盐、渗透(PEG)、高温和低温4种胁迫下的表达量均上升,ChDof03基因对高盐胁迫的反应最敏感,ChDof01基因对低温胁迫的响应最敏感,ChDof11基因在渗透、高温和低温胁迫下的表达量均有极显著的提高,而ChDof7和ChDof08基因在4种胁迫诱导下的表达量均降低。【结论】共鉴定出23个Dof家族成员,欧李ChDof11、ChDof12、ChDof17这3个基因在逆境胁迫中均有控制功能,ChDof7和ChDof08这2个基因则在逆境胁迫中均起负调节作用。Dof基因在欧李对逆境胁迫的响应中发挥着重要作用。
文摘阐述DNA-binding with one finger(Dof)转录因子在作物中应答极端温度、干旱和盐胁迫等逆境的分子机制及其改良农艺性状的作用;介绍Dof转录因子在作物中响应逆境的信号感知方式和信号转导途径,分析其基因表达调控过程的调控机理以及对胁迫耐受力与重要次生代谢产物(RFOs等)等积累的影响。同时从多信号网络调控机制以及全球气候变化对作物可持续和高质量生产的需求角度,对进一步研究和利用Dof转录因子进行作物生物育种的前景和方向作展望。
文摘3Do F VR是VR视频的一种代表性形态,也是目前虚拟现实领域普遍应用的形式。图像质量是一项会影响用户真实沉浸视觉感受的VR视频QoE的重要指标。目前国内外暂未形成VR视频领域图像质量主观评价的标准方法,为此,本文研究提出了一套3Do F VR视频图像质量主观评价方法。文章首先对VR视频主观评价的挑战、国内外进展进行分析调研,随后着重阐述了3Do F VR视频主观评价前期准备研究、主观评价量表设计、主观评价打分方法改进、实验序列制作等环节,最后进行了3DoF VR视频图像质量主观评价实验,并对实验数据进行了分析和总结。
