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
Redundant or hyper-redundant mobile manipulator can give lots of assistance to astronauts in space station. The design and implementation of a hyper-redundant mobile manipulator system are described, which is composed...Redundant or hyper-redundant mobile manipulator can give lots of assistance to astronauts in space station. The design and implementation of a hyper-redundant mobile manipulator system are described, which is composed of an 8 DOF module robot and a 1 DOF motorized rail. Inverse kinematic resolution of the system is discussed and one simplified control method based on joint limit avoidance and configuration optimization is proposed. Simulation and experimental results are presented.展开更多
As for the complex operational tasks in the unstructured environment with narrow workspace and numerous obstacles,the traditional robots cannot accomplish these mentioned complex operational tasks and meet the dexteri...As for the complex operational tasks in the unstructured environment with narrow workspace and numerous obstacles,the traditional robots cannot accomplish these mentioned complex operational tasks and meet the dexterity demands.The hyper-redundant bionic robots can complete complex tasks in the unstructured environments by simulating the motion characteristics of the elephant’s trunk and octopus tentacles.Compared with traditional robots,the hyper-redundant bionic robots can accomplish complex tasks because of their flexible structure.A hyper-redundant elephant’s trunk robot(HRETR)with an open structure is developed in this paper.The content includes mechanical structure design,kinematic analysis,virtual prototype simulation,control system design,and prototype building.This design is inspired by the flexible motion of an elephant’s trunk,which is expansible and is composed of six unit modules,namely,3UPS-PS parallel in series.First,the mechanical design of the HRETR is completed according to the motion characteristics of an elephant’s trunk and based on the principle of mechanical bionic design.After that,the backbone mode method is used to establish the kinematic model of the robot.The simulation software SolidWorks and ADAMS are combined to analyze the kinematic characteristics when the trajectory of the end moving platform of the robot is assigned.With the help of ANSYS,the static stiffness of each component and the whole robot is analyzed.On this basis,the materials of the weak parts of the mechanical structure and the hardware are selected reasonably.Next,the extensible structures of software and hardware control system are constructed according to the modular and hierarchical design criteria.Finally,the prototype is built and its performance is tested.The proposed research provides a method for the design and development for the hyper-redundant bionic robot.展开更多
The design of space hyper-redundant robot with high dexterity is problem with great complexity. Taking the aim at robot product seriation and combination design, the combination design method of space hyper-redundant ...The design of space hyper-redundant robot with high dexterity is problem with great complexity. Taking the aim at robot product seriation and combination design, the combination design method of space hyper-redundant robot based on the omnidirectional unit arm of 3 degrees of freedom (d.o.f) is proposed in this paper. The kinematics model of this kind of robot is established through the equivalent mechanism model. On the basis of successful research on 3-d.o.f unit arm, the 7-d.o.f bionics arm redundant robot with double unit arm has been developed further.The content discussed in this paper is very important to the robot technology in future space station, nuclear industry andunderwater work on the sea floor.展开更多
In this study,a hyper-redundant manipulator was designed for detection and searching in narrow spaces for aerospace and earthquake rescue applications.A forward kinematics equation for the hyper-redundant manipulator ...In this study,a hyper-redundant manipulator was designed for detection and searching in narrow spaces for aerospace and earthquake rescue applications.A forward kinematics equation for the hyper-redundant manipulator was derived using the homogeneous coordinate transformation method.Based on the modal function backbone curve method and the known path,an improved modal method for the backbone curves was proposed.First,the configuration of the backbone curve for the hyper-redundant manipulator was divided into two parts:a mode function curve segment of the mode function and a known path segment.By changing the discrete points along the known path,the backbone curve for the manipulator when it reached a specified path point was dynamically obtained,and then the joint positions of the manipulator were fitted to the main curve by dichotomy.Combined with engineering examples,simulation experiments were performed using the new algorithm to extract mathematical models for external narrow space environments.The experimental results showed that when using the new algorithm,the hyper-redundant manipulator could complete the tasks of passing through curved pipes and moving into narrow workspaces.The effectiveness of the algorithm was also proven by these experiments.展开更多
A novel hyper-redundant manipulator named RT1 is designed and studied. The unique feature of RT1 is all degrees of freedom (DOF) are actuated with only one motor via special designed hinge bar universal joints. The me...A novel hyper-redundant manipulator named RT1 is designed and studied. The unique feature of RT1 is all degrees of freedom (DOF) are actuated with only one motor via special designed hinge bar universal joints. The mechanisms of RT1 are introduced in detail. Some experiments are carried out in order to test the movability and adaptability of the manipulator. RT1 is actuated by pulse string and acts discretely. The discrete working space of RT1 is described and the parameter optimization for kinematical redundancy resolution is studied also. The optimization criterion is altering the design parameter as little as possible during manipulator's motion from the initial position to the expected position. An optimization example is given that is realized with Matlab optimize tool-box.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Redundant or hyper-redundant mobile manipulator can give lots of assistance to astronauts in space station. The design and implementation of a hyper-redundant mobile manipulator system are described, which is composed of an 8 DOF module robot and a 1 DOF motorized rail. Inverse kinematic resolution of the system is discussed and one simplified control method based on joint limit avoidance and configuration optimization is proposed. Simulation and experimental results are presented.
基金Supported by National Natural Science Foundation of China(Grant No.51375288)Science and Technology Program of Guangdong Province of China(Grant No.2020ST004)+1 种基金Department of Education of Guangdong Province of China(Grant No.2017KZDXM036and Special Project for Science and Technology Innovation Team of Foshan City of China(Grant No.2018IT100052).
文摘As for the complex operational tasks in the unstructured environment with narrow workspace and numerous obstacles,the traditional robots cannot accomplish these mentioned complex operational tasks and meet the dexterity demands.The hyper-redundant bionic robots can complete complex tasks in the unstructured environments by simulating the motion characteristics of the elephant’s trunk and octopus tentacles.Compared with traditional robots,the hyper-redundant bionic robots can accomplish complex tasks because of their flexible structure.A hyper-redundant elephant’s trunk robot(HRETR)with an open structure is developed in this paper.The content includes mechanical structure design,kinematic analysis,virtual prototype simulation,control system design,and prototype building.This design is inspired by the flexible motion of an elephant’s trunk,which is expansible and is composed of six unit modules,namely,3UPS-PS parallel in series.First,the mechanical design of the HRETR is completed according to the motion characteristics of an elephant’s trunk and based on the principle of mechanical bionic design.After that,the backbone mode method is used to establish the kinematic model of the robot.The simulation software SolidWorks and ADAMS are combined to analyze the kinematic characteristics when the trajectory of the end moving platform of the robot is assigned.With the help of ANSYS,the static stiffness of each component and the whole robot is analyzed.On this basis,the materials of the weak parts of the mechanical structure and the hardware are selected reasonably.Next,the extensible structures of software and hardware control system are constructed according to the modular and hierarchical design criteria.Finally,the prototype is built and its performance is tested.The proposed research provides a method for the design and development for the hyper-redundant bionic robot.
文摘The design of space hyper-redundant robot with high dexterity is problem with great complexity. Taking the aim at robot product seriation and combination design, the combination design method of space hyper-redundant robot based on the omnidirectional unit arm of 3 degrees of freedom (d.o.f) is proposed in this paper. The kinematics model of this kind of robot is established through the equivalent mechanism model. On the basis of successful research on 3-d.o.f unit arm, the 7-d.o.f bionics arm redundant robot with double unit arm has been developed further.The content discussed in this paper is very important to the robot technology in future space station, nuclear industry andunderwater work on the sea floor.
基金The authors gratefully acknowledge the financial support provided by the National Key Research&Development Project of China(Grant No.2019YFB1311203).
文摘In this study,a hyper-redundant manipulator was designed for detection and searching in narrow spaces for aerospace and earthquake rescue applications.A forward kinematics equation for the hyper-redundant manipulator was derived using the homogeneous coordinate transformation method.Based on the modal function backbone curve method and the known path,an improved modal method for the backbone curves was proposed.First,the configuration of the backbone curve for the hyper-redundant manipulator was divided into two parts:a mode function curve segment of the mode function and a known path segment.By changing the discrete points along the known path,the backbone curve for the manipulator when it reached a specified path point was dynamically obtained,and then the joint positions of the manipulator were fitted to the main curve by dichotomy.Combined with engineering examples,simulation experiments were performed using the new algorithm to extract mathematical models for external narrow space environments.The experimental results showed that when using the new algorithm,the hyper-redundant manipulator could complete the tasks of passing through curved pipes and moving into narrow workspaces.The effectiveness of the algorithm was also proven by these experiments.
文摘A novel hyper-redundant manipulator named RT1 is designed and studied. The unique feature of RT1 is all degrees of freedom (DOF) are actuated with only one motor via special designed hinge bar universal joints. The mechanisms of RT1 are introduced in detail. Some experiments are carried out in order to test the movability and adaptability of the manipulator. RT1 is actuated by pulse string and acts discretely. The discrete working space of RT1 is described and the parameter optimization for kinematical redundancy resolution is studied also. The optimization criterion is altering the design parameter as little as possible during manipulator's motion from the initial position to the expected position. An optimization example is given that is realized with Matlab optimize tool-box.
