Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the a...Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the algorithms of points and constrained edge insertion, there are very a few researches on constrained edge deletion in CD-TIN. Based on the analysis of the polymorphism of constrained edge, virtual points are used to describe the intersection of constrained edges. A new algorithm is presented, called as influence domain retriangulating for virtual point （IDRVP）, to delete constrained edges with virtual points. The algorithm is complete in topology. Finally, the algorithm is tested by some applications cases.展开更多
In this study,a virtual-point concept was introduced into fiber-laser photoacoustic tomography to improve the elevational image resolution.The flexible fiber laser was bent into an arc shape to conform to the ultrasou...In this study,a virtual-point concept was introduced into fiber-laser photoacoustic tomography to improve the elevational image resolution.The flexible fiber laser was bent into an arc shape to conform to the ultrasound wavefront,which formed an ultrasound focus at the center of the arc.The synthetic aperture focusing technique was utilized to reconstruct the images;as a result,the elevational resolution particularly within the out-of-focus region was considerably improved compared to the resolution of an image retrieved by multiplexing the PA time-resolved signals with sound velocity.The all-optical fiber-laser photoacoustic tomography system with a high spatial resolution has potential for various applications,including biomedical research and preclinical/clinical diagnosis.展开更多
This paper presents a novel control approach for achieving robust posture control in legged locomotion,specifically for SLIP-like bipedal running and quadrupedal bounding with trunk stabilization.The approach is based...This paper presents a novel control approach for achieving robust posture control in legged locomotion,specifically for SLIP-like bipedal running and quadrupedal bounding with trunk stabilization.The approach is based on the virtual pendulum concept observed in human and animal locomotion experiments,which redirects ground reaction forces to a virtual support point called the Virtual Pivot Point(VPP)during the stance phase.Using the hybrid averaging theorem,we prove the upright posture stability of bipedal running with a fixed VPP position and propose a VPP angle feedback controller for online VPP adjustment to improve performance and convergence speed.Additionally,we present the first application of the VPP concept to quadrupedal posture control and design a VPP position feedback control law to enhance robustness in quadrupedal bounding.We evaluate the effectiveness of the proposed VPP-based controllers through various simulations,demonstrating their effectiveness in posture control of both bipedal running and quadrupedal bounding.The performance of the VPP-based control approach is further validated through experimental validation on a quadruped robot,SCIT Dog,for stable bounding motion generation at different forward speeds.展开更多
The growing ubiquity of Wi-Fi networks combined with the integration of low-cost Wi-Fi chipsets in all devices makes Wi-Fi as the wireless technology the most used for accessing to internet [1]. This means that the de...The growing ubiquity of Wi-Fi networks combined with the integration of low-cost Wi-Fi chipsets in all devices makes Wi-Fi as the wireless technology the most used for accessing to internet [1]. This means that the development of a Wi-Fi strategy has become an imperative for almost all operators worldwide. In this context, APs (Access Points) have to become as secure as cellular networks. Furthermore, authentication process between a mobile device and an access point has to be automated, without user constraining configuration. For reaching this purpose, client must have different credentials depending on authentication method. Our goal is to create an architecture that is both ergonomic and flexible in order to meet the need for connection and client mobility. We use NFC technology as a radio channel for starting communication with the network. The communication initiation will instantiate a virtual Wi-Fi AP and distribute all policies and access certificates for an authentication based on EAP-TLS (it could be extended to any EAP method for 802.1X standard). The end result of our new topology is to allow access to services through a virtual Wi-Fi AP with an enterprise-grade in a public hotspot.展开更多
文摘Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the algorithms of points and constrained edge insertion, there are very a few researches on constrained edge deletion in CD-TIN. Based on the analysis of the polymorphism of constrained edge, virtual points are used to describe the intersection of constrained edges. A new algorithm is presented, called as influence domain retriangulating for virtual point （IDRVP）, to delete constrained edges with virtual points. The algorithm is complete in topology. Finally, the algorithm is tested by some applications cases.
基金This research was supported by the National Natural Science Foundation of China(NSFC)(61705082,U1701268)Natural Science Foundation of Guangdong Province(2018030310587)+1 种基金Fundamental Research Funds for the Central Universities(21617304)Guangdong Province High-Level Talents Introduction Plan(2017GC010420).
文摘In this study,a virtual-point concept was introduced into fiber-laser photoacoustic tomography to improve the elevational image resolution.The flexible fiber laser was bent into an arc shape to conform to the ultrasound wavefront,which formed an ultrasound focus at the center of the arc.The synthetic aperture focusing technique was utilized to reconstruct the images;as a result,the elevational resolution particularly within the out-of-focus region was considerably improved compared to the resolution of an image retrieved by multiplexing the PA time-resolved signals with sound velocity.The all-optical fiber-laser photoacoustic tomography system with a high spatial resolution has potential for various applications,including biomedical research and preclinical/clinical diagnosis.
基金This work was supported by the Touyan Innovation Program of Heilongjiang Province.
文摘This paper presents a novel control approach for achieving robust posture control in legged locomotion,specifically for SLIP-like bipedal running and quadrupedal bounding with trunk stabilization.The approach is based on the virtual pendulum concept observed in human and animal locomotion experiments,which redirects ground reaction forces to a virtual support point called the Virtual Pivot Point(VPP)during the stance phase.Using the hybrid averaging theorem,we prove the upright posture stability of bipedal running with a fixed VPP position and propose a VPP angle feedback controller for online VPP adjustment to improve performance and convergence speed.Additionally,we present the first application of the VPP concept to quadrupedal posture control and design a VPP position feedback control law to enhance robustness in quadrupedal bounding.We evaluate the effectiveness of the proposed VPP-based controllers through various simulations,demonstrating their effectiveness in posture control of both bipedal running and quadrupedal bounding.The performance of the VPP-based control approach is further validated through experimental validation on a quadruped robot,SCIT Dog,for stable bounding motion generation at different forward speeds.
文摘The growing ubiquity of Wi-Fi networks combined with the integration of low-cost Wi-Fi chipsets in all devices makes Wi-Fi as the wireless technology the most used for accessing to internet [1]. This means that the development of a Wi-Fi strategy has become an imperative for almost all operators worldwide. In this context, APs (Access Points) have to become as secure as cellular networks. Furthermore, authentication process between a mobile device and an access point has to be automated, without user constraining configuration. For reaching this purpose, client must have different credentials depending on authentication method. Our goal is to create an architecture that is both ergonomic and flexible in order to meet the need for connection and client mobility. We use NFC technology as a radio channel for starting communication with the network. The communication initiation will instantiate a virtual Wi-Fi AP and distribute all policies and access certificates for an authentication based on EAP-TLS (it could be extended to any EAP method for 802.1X standard). The end result of our new topology is to allow access to services through a virtual Wi-Fi AP with an enterprise-grade in a public hotspot.
