The DFH-3B platform is a geosynchronous common satellite platform whose capability is between that of the current DFH-3 and DFH-4 platforms.The DFH-3B platform makes comprehensive use of the most internationally advan...The DFH-3B platform is a geosynchronous common satellite platform whose capability is between that of the current DFH-3 and DFH-4 platforms.The DFH-3B platform makes comprehensive use of the most internationally advanced space technologies such as Lithium-ion battery,integrated electronics,high efficiency thermal control and electric propulsion.The development of the platform will meet China's imminent demands for the development of satellites for civil communications,and greatly enhance China's competitiveness in the international communications satellite market.展开更多
The unique design for a novel 6-SPS parallel 3-dimensional platformmanipulator with an orthogonal configuration is investigated. The layout feature of the parallelmanipulator is described. Its force/motion transmissio...The unique design for a novel 6-SPS parallel 3-dimensional platformmanipulator with an orthogonal configuration is investigated. The layout feature of the parallelmanipulator is described. Its force/motion transmission capability, evaluation criteria arepresented. At the orthogonal configuration, the criteria and the relationships between the criteriaand the link lengths are analyzed, which is important since it can provide designer a piece ofvaluable information about how to choose the linear actuators. From the analysis of the results itis shown that the force/motion transmission capabilities of the parallel manipulator arecharacterized by isotropy at the orthogonal configuration. The manipulator is particularly suitablefor certain applications in 6-DOF micromanipulators and 6-axis force/moment transducers.展开更多
With the development of fluid-power transmission and control technology,electro-hydraulic-driven technology can significantly improve the load-carrying capacity,stiffness,and control accuracy of stabilization platform...With the development of fluid-power transmission and control technology,electro-hydraulic-driven technology can significantly improve the load-carrying capacity,stiffness,and control accuracy of stabilization platforms.However,compared with mechanically driven platforms,the stiffness and damping of the fluid,as well as the coupling effect between the fluid and the structure need to be considered for electro-hydraulic-driven parallel stabilization platforms,making the modal and dynamic response characteristics of the mechanism more complex.With the aim of solving the aforementioned issues,we research the electro-hydraulic driven 3-UPS/S parallel stabilization platform considering the hinge stiffness.Moreover,the characteristic vibration equation of the mechanism is established using the virtual work principle.Subsequently,the variation characteristics of the natural frequency and the vibration response according to the position of the mechanism are analyzed based on the dynamic equation.Finally,the correctness of the model is verified by a modal test and Runge-Kutta methods.This study provides a theoretical basis for the dynamic design of electrohydraulic-driven parallel mechanisms.展开更多
Many cell-matrix interaction studies have proved that dynamic changes in the extracellular matrix(ECM)are crucial to maintain cellular properties and behaviors.Thus,developing materials that can recapitulate the dynam...Many cell-matrix interaction studies have proved that dynamic changes in the extracellular matrix(ECM)are crucial to maintain cellular properties and behaviors.Thus,developing materials that can recapitulate the dynamic attributes of the ECM is highly desired for threedimensional(3 D)cell culture platforms.To this end,we sought to develop a hydrogel system that would enable dynamic and reversible turning of its mechanical and biochemical properties,thus facilitating the control of cell culture to imitate the natural ECM.Herein,a hydrogel with dynamic mechanics and a biochemistry based on an addition-fragmentation chain transfer(AFCT)reaction was constructed.Thiol-modified hyaluronic acid(HA)and allyl sulfide-modifiedε-poly-L-lysine(EPL)were synthesized to form hydrogels,which were non-swellable and biocompatible.The reversible modulus of the hydrogel was first achieved through the AFCT reaction;the modulus can also be regulated stepwise by changing the dose of UVA irradiation.Dynamic patterning of fluorescent markers in the hydrogel was also realized.Therefore,this dynamically controllable hydrogel has great potential as a 3 D cell culture platform for tissue engineering applications.展开更多
Virtual simulation experiment teaching gradually becomes the trend of the computer-related education practice.Through analyzing the problems existed in current computer experiment teaching,this paper proposes the idea...Virtual simulation experiment teaching gradually becomes the trend of the computer-related education practice.Through analyzing the problems existed in current computer experiment teaching,this paper proposes the idea of building virtual simulation experiment platform based on 3R-4A computer system and clarifies the design technology,including frame,characteristic and innovation,resource sharing and management,condition protection and so on.展开更多
A new telecommunications satellite was launched from Xichang Launch Center on Nov. 30, 1994 and was put into a geosynchronous transfer orbit 24 minutes after its lift-off. It was launched by a Long-March 3A launch veh...A new telecommunications satellite was launched from Xichang Launch Center on Nov. 30, 1994 and was put into a geosynchronous transfer orbit 24 minutes after its lift-off. It was launched by a Long-March 3A launch vehicle, which was developed earlier in 1994 by the China Academy of Launch Vehicle Teehnology. The Long-展开更多
文摘The DFH-3B platform is a geosynchronous common satellite platform whose capability is between that of the current DFH-3 and DFH-4 platforms.The DFH-3B platform makes comprehensive use of the most internationally advanced space technologies such as Lithium-ion battery,integrated electronics,high efficiency thermal control and electric propulsion.The development of the platform will meet China's imminent demands for the development of satellites for civil communications,and greatly enhance China's competitiveness in the international communications satellite market.
基金This project is supported by National 863 Plan of China (No. 512-9804- 02) and 863 Opening Robot Laboratory Foundation of Shenyang Institute Automation of Chinese Academy of Sciences.
文摘The unique design for a novel 6-SPS parallel 3-dimensional platformmanipulator with an orthogonal configuration is investigated. The layout feature of the parallelmanipulator is described. Its force/motion transmission capability, evaluation criteria arepresented. At the orthogonal configuration, the criteria and the relationships between the criteriaand the link lengths are analyzed, which is important since it can provide designer a piece ofvaluable information about how to choose the linear actuators. From the analysis of the results itis shown that the force/motion transmission capabilities of the parallel manipulator arecharacterized by isotropy at the orthogonal configuration. The manipulator is particularly suitablefor certain applications in 6-DOF micromanipulators and 6-axis force/moment transducers.
基金National Key Research and Development Program of China(Grant No.2019YFB2005303)General Fund of the National Natural Science Foundation of China(Grant No.52175066)+1 种基金Hebei Provincial Natural Science Foundation of China(Grant No.E2020203090)Hebei Provincial Key Science and Technology Projects in the Colleges and Universities of China(Grant No.ZD2022052)。
文摘With the development of fluid-power transmission and control technology,electro-hydraulic-driven technology can significantly improve the load-carrying capacity,stiffness,and control accuracy of stabilization platforms.However,compared with mechanically driven platforms,the stiffness and damping of the fluid,as well as the coupling effect between the fluid and the structure need to be considered for electro-hydraulic-driven parallel stabilization platforms,making the modal and dynamic response characteristics of the mechanism more complex.With the aim of solving the aforementioned issues,we research the electro-hydraulic driven 3-UPS/S parallel stabilization platform considering the hinge stiffness.Moreover,the characteristic vibration equation of the mechanism is established using the virtual work principle.Subsequently,the variation characteristics of the natural frequency and the vibration response according to the position of the mechanism are analyzed based on the dynamic equation.Finally,the correctness of the model is verified by a modal test and Runge-Kutta methods.This study provides a theoretical basis for the dynamic design of electrohydraulic-driven parallel mechanisms.
基金financially supported by the National Natural Science Foundation of China(Nos.21803069 and 21975249)。
文摘Many cell-matrix interaction studies have proved that dynamic changes in the extracellular matrix(ECM)are crucial to maintain cellular properties and behaviors.Thus,developing materials that can recapitulate the dynamic attributes of the ECM is highly desired for threedimensional(3 D)cell culture platforms.To this end,we sought to develop a hydrogel system that would enable dynamic and reversible turning of its mechanical and biochemical properties,thus facilitating the control of cell culture to imitate the natural ECM.Herein,a hydrogel with dynamic mechanics and a biochemistry based on an addition-fragmentation chain transfer(AFCT)reaction was constructed.Thiol-modified hyaluronic acid(HA)and allyl sulfide-modifiedε-poly-L-lysine(EPL)were synthesized to form hydrogels,which were non-swellable and biocompatible.The reversible modulus of the hydrogel was first achieved through the AFCT reaction;the modulus can also be regulated stepwise by changing the dose of UVA irradiation.Dynamic patterning of fluorescent markers in the hydrogel was also realized.Therefore,this dynamically controllable hydrogel has great potential as a 3 D cell culture platform for tissue engineering applications.
文摘Virtual simulation experiment teaching gradually becomes the trend of the computer-related education practice.Through analyzing the problems existed in current computer experiment teaching,this paper proposes the idea of building virtual simulation experiment platform based on 3R-4A computer system and clarifies the design technology,including frame,characteristic and innovation,resource sharing and management,condition protection and so on.
文摘A new telecommunications satellite was launched from Xichang Launch Center on Nov. 30, 1994 and was put into a geosynchronous transfer orbit 24 minutes after its lift-off. It was launched by a Long-March 3A launch vehicle, which was developed earlier in 1994 by the China Academy of Launch Vehicle Teehnology. The Long-
