The expansion of Global Navigation Satellite Systems(GNSS)and Regional Navigation Satellite Systems(RNSS),along with broadcasting of additional signals,ofers more options for Precise Point Positioning(PPP).Utilizing a...The expansion of Global Navigation Satellite Systems(GNSS)and Regional Navigation Satellite Systems(RNSS),along with broadcasting of additional signals,ofers more options for Precise Point Positioning(PPP).Utilizing a number of constellations and frequencies provides more precise and reliable Observable-Specifc Bias(OSBs)and atmospheric products,thereby enhancing the performance of PPP with Ambiguity Resolution(PPP-AR)and PPP-RTK systems.Additionally,the emergence and refnement of satellite-based augmentation services targeting PPP,such as BDS-3 Precise Point Positioning(PPP-B2b)and High Accuracy Service(HAS),have further expanded the applications of multi-GNSS and multi-frequency PPP.In this contribution,we comprehensively overview the developmental history of major systems and the construction of global satellite-based augmentation systems.The model of multiGNSS and multi-frequency PPP-RTK is then established,encompassing both the server and user sides.Benefting from the modernization of GPS,refnement of Galileo,and stable operation of BDS,the convergence time of PPP foat solutions is less than 9 min,while the convergence time of fxed solutions is under 5 min.The PPP-RTK system can achieve instantaneous convergence with high-confdence atmospheric products,maintaining positioning accuracy within 2.5 cm.Furthermore,vehicular experiments demonstrate that the PPP-RTK technology can maintain a positioning accuracy of around 10 cm even in rapidly changing observational conditions.For augmentation services such as PPP-B2b and HAS,after correcting for orbit,clock,and code biases,the convergence time can be reduced to under 15 min,with positioning accuracy of approximately 16 cm.Finally,we present our outlook for the future of BDS.展开更多
Nature provides a wealth of bio-inspiration for advanced material research.Assembling various nanomaterials into biomimetic microtextures with bioinspired functionalities has spurred increasing research interests and ...Nature provides a wealth of bio-inspiration for advanced material research.Assembling various nanomaterials into biomimetic microtextures with bioinspired functionalities has spurred increasing research interests and facilitated technological advances in various applications.In recent years,two-dimensional materials(2DMs)have emerged as important building block units in the biomimicry field due to their distinct chemical,physical,electrical,electrochemical,and catalytic properties.In this review article,various mechanically driven assembly approaches are summarized to fabricate various genealogies of biomimetic 2DM microtextures with bio-inspired multifunctionality.First,sequential deformation strategies are discussed to programmably construct higher dimensional 2DM microtextures,ranging from wrinkles/crumples(one-time deformation)to multiscale hierarchies(multiple deformations).Next,the current progress using higher dimensional 2DM microtextures to imitate different biological structures and/or induce bio-inspired multifunctionality is systematically summarized.Four showcases of bio-inspiration and biomimicry using different 2DM nanosheets are highlighted:(1)wrinkle patterns of an earthworm that spur the design of strain sensors with programmable working ranges and sensitivities,(2)wrinkle appearance of a Shar-Pei dog that motivates the fabrication of stretchable energy storage devices,(3)hierarchical scale textures of a desert lizard that inspire cation-induced gelation platforms for 2DM aerogels,and(4)wrinkle skin of an elephant that influences the development of 2DM protective skin for soft robots.Finally,challenges and future opportunities of adopting 2DM nanosheets to assemble biomimetic microstructures with synergistic functionalities are discussed.展开更多
1 Introduction.With the advent of artificial intelligence,it is becoming increasingly common to leverage deep learning technologies to provide intelligent services in Web apps[1].Compared with traditional approaches w...1 Introduction.With the advent of artificial intelligence,it is becoming increasingly common to leverage deep learning technologies to provide intelligent services in Web apps[1].Compared with traditional approaches where deep neural network(DNN)runs at cloud servers,DNN inference in Web browsers avoids serverconnections,boostingtheresponsivenesssand enhancing user privacy of Web apps[2].Typically,GPU acceleration is required during DNN inference,especially on enddevices.展开更多
基金funded by the National Science Fund for Distinguished Young Scholars of China(Grant No.42425003)the National Natural Science Foundation of China(Grant No.42388102,No.42230104)the Fundamental Research Funds for the Central Universities(No.2042025kf0026).
文摘The expansion of Global Navigation Satellite Systems(GNSS)and Regional Navigation Satellite Systems(RNSS),along with broadcasting of additional signals,ofers more options for Precise Point Positioning(PPP).Utilizing a number of constellations and frequencies provides more precise and reliable Observable-Specifc Bias(OSBs)and atmospheric products,thereby enhancing the performance of PPP with Ambiguity Resolution(PPP-AR)and PPP-RTK systems.Additionally,the emergence and refnement of satellite-based augmentation services targeting PPP,such as BDS-3 Precise Point Positioning(PPP-B2b)and High Accuracy Service(HAS),have further expanded the applications of multi-GNSS and multi-frequency PPP.In this contribution,we comprehensively overview the developmental history of major systems and the construction of global satellite-based augmentation systems.The model of multiGNSS and multi-frequency PPP-RTK is then established,encompassing both the server and user sides.Benefting from the modernization of GPS,refnement of Galileo,and stable operation of BDS,the convergence time of PPP foat solutions is less than 9 min,while the convergence time of fxed solutions is under 5 min.The PPP-RTK system can achieve instantaneous convergence with high-confdence atmospheric products,maintaining positioning accuracy within 2.5 cm.Furthermore,vehicular experiments demonstrate that the PPP-RTK technology can maintain a positioning accuracy of around 10 cm even in rapidly changing observational conditions.For augmentation services such as PPP-B2b and HAS,after correcting for orbit,clock,and code biases,the convergence time can be reduced to under 15 min,with positioning accuracy of approximately 16 cm.Finally,we present our outlook for the future of BDS.
基金support provided by the Start-Up Fund of University of Maryland,College Park(KFS No.:2957431 to P.-Y.Chen)Fundings for this research were provided by Energy Innovation Seed Grant from Maryland Energy Innovation Institute(MEI^2)(KFS No.:2957597 to P.-Y.Chen)supported by the Air Force Office of Scientific Research under award number FA2386-21-1-4065(KFS No.:5284212 to P.-Y.Chen)。
文摘Nature provides a wealth of bio-inspiration for advanced material research.Assembling various nanomaterials into biomimetic microtextures with bioinspired functionalities has spurred increasing research interests and facilitated technological advances in various applications.In recent years,two-dimensional materials(2DMs)have emerged as important building block units in the biomimicry field due to their distinct chemical,physical,electrical,electrochemical,and catalytic properties.In this review article,various mechanically driven assembly approaches are summarized to fabricate various genealogies of biomimetic 2DM microtextures with bio-inspired multifunctionality.First,sequential deformation strategies are discussed to programmably construct higher dimensional 2DM microtextures,ranging from wrinkles/crumples(one-time deformation)to multiscale hierarchies(multiple deformations).Next,the current progress using higher dimensional 2DM microtextures to imitate different biological structures and/or induce bio-inspired multifunctionality is systematically summarized.Four showcases of bio-inspiration and biomimicry using different 2DM nanosheets are highlighted:(1)wrinkle patterns of an earthworm that spur the design of strain sensors with programmable working ranges and sensitivities,(2)wrinkle appearance of a Shar-Pei dog that motivates the fabrication of stretchable energy storage devices,(3)hierarchical scale textures of a desert lizard that inspire cation-induced gelation platforms for 2DM aerogels,and(4)wrinkle skin of an elephant that influences the development of 2DM protective skin for soft robots.Finally,challenges and future opportunities of adopting 2DM nanosheets to assemble biomimetic microstructures with synergistic functionalities are discussed.
基金the National Natural Science Foundation of China(Grant No.62102009)the Beijing Outstanding Young Scientist Program(No.BJJWZYJH01201910001004)。
文摘1 Introduction.With the advent of artificial intelligence,it is becoming increasingly common to leverage deep learning technologies to provide intelligent services in Web apps[1].Compared with traditional approaches where deep neural network(DNN)runs at cloud servers,DNN inference in Web browsers avoids serverconnections,boostingtheresponsivenesssand enhancing user privacy of Web apps[2].Typically,GPU acceleration is required during DNN inference,especially on enddevices.
