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Economical Quadrupedal Multi-Gait Locomotion via Gait-Heuristic Reinforcement Learning

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Journal of Bionic engineering 2024年第4期21卷 1720-1732页

作者： Lang Wei Jinzhou Zou Xi Yu Liangyu Liu Jianbin Liao Wei Wang Tong Zhang School of Power and Mechanical engineering Wuhan UniversityLuojiashanWuhan430072HubeiChina state key laboratory of information engineering in surveying Mapping and Remote SensingWuhan UniversityLuojiashanWuhan430072HubeiChina

In order to strike a balance between achieving desired velocities and minimizing energy consumption,legged animals have the ability to adopt the appropriate gait pattern and seamlessly transition to another if *** ability makes them more versatile and efficient when traversing natural terrains,and more suitable for long *** the same way,it is meaningful and important for quadruped robots to master this *** achieve this goal,we propose an effective gait-heuristic reinforcement learning framework in which multiple gait locomotion and smooth gait transitions automatically emerge to reach target velocities while minimizing energy *** incorporate a novel trajectory generator with explicit gait information as a memory mechanism into the deep reinforcement learning *** allows the quadruped robot to adopt reliable and distinct gait patterns while benefiting from a warm start provided by the trajectory ***,we investigate the key factors contributing to the emergence of multiple gait *** tested our framework on a closed-chain quadruped robot and demonstrated that the robot can change its gait patterns,such as standing,walking,and trotting,to adopt the most energy-efficient gait at a given ***,we deploy our learned controller to a quadruped robot and demonstrate the energy efficiency and robustness of our method.

关键词： Legged robots Deep reinforcement learning Central pattern generator Quadrupedal gait

Demand and key technology for a LEO constellation as augmentation of satellite navigation systems

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Satellite Navigation 2024年第1期5卷 1-9页

作者： Yuanxi Yang Yue Mao Xia Ren Xiaolin Jia Bjiao Sun Xi’an Research Institute of surveying and Mapping Xi’an710054ShaanxiChina state National key laboratory of Geo-information engineering Xi’an710054ShaanxiChina

A Low Earth Orbit(LEO)constellation augmenting satellite navigation is important in the future development of Global Navigation Satellite System(GNSS).GNSS augmented by LEO constellations can improve not only the accuracy of Positioning,Navigation,and Timing(PNT),but also the consistency and reliability of secure PNT *** paper mainly analyzes the diverse demands of different PNT users for LEO augmented GNSS,including the precision demand in real-time,the availability demand in special areas,the navigation signal enhancement demand in complex electromagnetic environments,and the integrity demand with high ***,the possible contributions of LEO constellations to PNT performance are analyzed from multiple aspects.A particular attention is paid to the special PNT user requirements that cannot be fulfilled with existing GNSS,such as the PNT service demand in the polar regions and the onboard GNSS orbit determination demand of some LEO *** key technologies to be considered in the constellation design,function realization,and payload development of the LEO-augmented navigation system are summarized.

关键词： Low earth orbit navigation constellation Accuracy augmentation Orbit determination Integrity

Monitoring Surface Deformation Using Distributed Scatterers InSAR

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Journal of Geodesy and Geoinformation Science 2024年第1期7卷 42-58页

作者： LI Haocheng DONG Jie WANG Yi’an LIAO Mingsheng state key laboratory of information engineering in surveying Mapping and Remote SensingWuhan UniversityWuhan 430079China School of Remote Sensing and information engineering Wuhan UniversityWuhan 430079China

In the past two decades,extensive and in-depth research has been conducted on Time Series InSAR technology with the advancement of high-performance SAR satellites and the accumulation of big SAR *** introduction of distributed scatterers in Distributed Scatterers InSAR(DS-InSAR)has significantly expanded the application scenarios of InSAR geodetic measurement by increasing the number of measurement *** study traces the history of DS-InSAR,presents the definition and characteristics of distributed scatterers,and focuses on exploring the relationships and distinctions among proposed algorithms in two crucial steps:statistically homogeneous pixel selection and phase ***,the latest research progress in this field is tracked and the possible development direction in the future is *** simulation experiments and two real InSAR case studies,the proposed algorithms are compared and verified,and the advantages of DS-InSAR in deformation measurement practice are *** work not only offers insights into current trends and focal points for theoretical research on DS-InSAR but also provides practical cases and guidance for applied research.

关键词： InSAR permanent scatterers distributed scatterers statistically homogeneous pixel selection phase optimization

Long-term variation of Arctic Sudden Stratospheric Warmings(SSW) and potential causes

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Earth and Planetary Physics 2024年第5期8卷 742-752页

作者： QingRan Li ShaoDong Zhang KaiMing Huang ChunMing Huang Yun Gong WenTao Tang Zheng Ma School of Electronic information Wuhan University Guizhou Normal University key laboratory of Geospace Environment and Geodesy Ministry of Education state key laboratory of information engineering in surveying Mapping and Remote Sensing School of Electronic information engineering Jingchu University of Technology

Utilizing the European Centre for Medium-Range Weather Forecast(ECMWF) Reanalysis v5(ERA5), for the first time, we have confirmed close links among Sudden Stratospheric Warmings(SSWs) in the Northern Hemisphere(NH), the polar vortices, and stratospheric Planetary Waves(PWs) by analyzing and comparing their trends. Interestingly, within overall increasing trends, the duration and strength of SSWs exhibit increasing and decreasing trends before and after the winter of 2002, respectively. To reveal possible physical mechanisms driving these trends, we analyzed the long-term trends of the winter(from December to February) polar vortices and of stratospheric PWs with zonal wave number 1. Notably, our results show that in all three time periods(the entire period of 41winters, 1980 to 2020, and the two subperiods — 1980-2002 and 2002-2020) enhancing SSWs were always accompanied by weakening winter polar vortices and strengthening polar PWs like Stationary Planetary Waves(SPWs) and 16-day waves, and vice versa. This is the first proof, based on ERA5 long-term trend data, that weakening polar vortices and enhancing stratospheric PWs(especially SPWs) could cause an increase in SSWs.

关键词： sudden stratospheric warmings stationary planetary waves 16-day waves polar vortrices long-term trend correlation coefficient

Single-step-etched ultra-compact metamaterial grating coupler enabled by a hierarchical inverse design approach

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Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 119-126页

作者： Qiao Wang Ruiqi Luo Nan Liu Maojing Hou Bo Xiong Guandong Liu Wei Ma Intelligent Network Research Institute Zhejiang LabHangzhou 311100China state key laboratory of Modern Optical Instrumentation College of Information Science and Electronic EngineeringZhejiang UniversityHangzhou 310027China

With the concept of metamaterials introduced into integrated photonics,subwavelength structures have gained popularity for their ability to create devices with ultra-compact size,high performance,and versatile ***,traditional metamaterial design methods are usually based on empirical templates and physical approximations,lacking the ability to design free-form metamaterial structures and optimize entire devices *** this work,we propose a hierarchical inverse design approach that combines a conventional effective refractive index based metamaterial structures design with a follow-up global topology *** empirical metamaterial grating coupler design based on effective refractive index engineering faces inaccurate index extraction and insufficient approximation of wavevector matching conditions,which deteriorates coupling efficiency,especially for fully-etched devices with the decreased tapering ***,a subsequent overall topology optimization step can well compensate for the negative effect of the shrinking device footprint to increase the efficiency of the metamaterial grating *** demonstrate a 23μm×10μm ultra-compact metamaterial grating coupler with single-stepetched to couple light between a fiber and a 500 nm single-mode silicon waveguide in the *** measurement shows an insertion loss of 3.17 dB and a 3 dB bandwidth of 77 nm,making it the smallest footprint device ever reported.

关键词： waveguide hierarchical inverse

Multi-carrier Tb/s silicon photonic coherent receiver

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Science China(information Sciences) 2024年第1期67卷 284-291页

作者： Zhen WANG Xingfeng LI Jingchi LI Jian SHEN Yong ZHANG Yikai SU state key lab of Advanced Optical Communication Systems and Networks Department of Electronic EngineeringShanghai Jiao Tong University

We propose a silicon polarization-diversity coherent receiver for wavelength-multiplexing transmission without using the large-footprint arrayed waveguide grating(AWG).We have integrated our proposed coherent receiver on the silicon-on-insulator(SOI) platform for high-capacity *** the proposed coherent receiver,high-frequency photocurrent signals from other wavelengths are suppressed by electrical low-pass ***,the signal-signal beat interference(SSBI) generated from each wavelength is eliminated by the balanced *** two features lend to the proposed coherent receiver being free of the mm-scale *** have demonstrated our proposed coherent receiver to detect a 1.12-Tb/s wavelength-division-multiplexed and polarization-division-multiplexed 16-ary quadrature amplitude modulation(PDM-16-QAM) *** compact footprint of the silicon chip promises small-form-factor receivers for future ultra-high-capacity coherent communication systems that require a high integration level and low fabrication cost.

关键词： silicon photonics optical receivers coherent communication wavelength-division-multiplexing(WDM) polarization-division-multiplexing(PDM)

Robust textile-based spoof plasmonic frequency scanning antenna for on-body IoT applications

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Science China(information Sciences) 2024年第8期67卷 269-284页

作者： Zhao-Min CHEN Jun-Lin ZHAN Hao CHEN Ya LI Hongjun HE Wu YANG Zhen-Guo LIU Wei-Bing LU state key lab of Millimeter Waves School of Information Science and EngineeringSoutheast University Center for Flexible RF Technology Frontiers Science Center for Mobile Information Communication and SecuritySoutheast University Future Research laboratory China Mobile Research Institute Purple Mountain laboratories

Securing a comfortable, wearable compact frequency beam scanning antenna(FBSA) with robustness to deformation, low specific absorption rate(SAR), and good coverage of the surrounding environment for Internet of Things(IoT) applications, such as on-body navigation and wireless communication is an emerging challenge. In this work, a robust textile-based spoof plasmonic frequency scanning antenna utilizing higher-order modes is presented, which is also robust to deformation caused by the activities of the human body. The innovative design of the element ensures the high-efficiency transmission of the fundamental mode of spoof surface plasmon polaritons(SSPP) structure, providing the potential of being a multifunctional composite device in the compact on-body network. Besides, an artificial magnetic conductor(AMC) is designed underneath the SSPP structure, obtaining a low SAR value(0.113 W/kg), which ensures the safety of users. As a practical realization of this concept, a textile-based spoof plasmonic antenna was fabricated in the microwave regime and the performed experimental results show the proposed antenna has a single-beam radiation characteristic with a 70° beam scanning angle range when the frequency is 4.7–6.0 GHz with a high average realized gain of 13.15 dBi. And it still maintains a steady performance when faced with structure deformation, which proves its robustness. Wireless communication quality experiments are performed to demonstrate the proposed antenna can measure the angles of targets and realize wireless signal transmission to specific targets as the frequency varies, it may find great potential in the field of on-body IoT applications.

关键词： frequency beam scanning antenna (FBSA) Internet of Things (IoT) on-body communication spoof surface plasmon polaritons (SSPP) textile-based antenna

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Polyphenol-mediated interfacial deposition strategy for supported manganese oxide catalysts with excellent pollutant degradation performance

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Chinese Chemical Letters 2024年第5期35卷 493-498页

作者： Dong Cheng Youyou Feng Bingxi Feng Ke Wang Guoxin Song Gen Wang Xiaoli Cheng Yonghui Deng Jing Wei The key laboratory of Biomedical information engineering of Ministry of Education State Key Lab of Transducer TechnologySchool of Life Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China School of Environmental and Municipal engineering Xi’an University of Architecture and TechnologyXi’an 710055China Department of Chemistry State Key Laboratory of Molecular Engineering of PolymersState Key Laboratory of Transducer TechnologyFudan UniversityShanghai 200433China key laboratory of Functional Inorganic Material Chemistry Ministry of EducationSchool of Chemistry and Materials ScienceHeilongjiang UniversityHarbin 150080China

In persulfate-based advanced oxidation process(PS-AOPs),fixing nanosized metal oxide on processable substrates is highly desirable to avoid the aggregation and loss of nanocatalysts during the practical ***,it is still challenging to develop a versatile strategy for the deposition of metal oxide nanocatalysts on various substrates with different physicochemical ***,polyphenols are utilized as a“molecular glue”and reductant to mediate the interfacial deposition of MnO_(2) nanocatalysts on different ***_(2) nanocatalysts were in-situ grown on macroscope mineral substrates(e.g.,airstone)via an interfacial redox strategy between tannic acid(TA)and oxidized KMnO4,and then employed as a fixed catalyst of peroxymonosulfate(PMS)activation for treating pharmaceutical and personal care products(PPCPs)in *** fixed MnO_(2) exhibited superior catalytic performance toward different PPCPS via a singlet oxygen(^(1)O_(2))-dominated nonradical oxidation *** in the secondary effluent of wastewater treatment plants could be effectively removed by a fixed-bed column of the fixed MnO_(2) with long term *** cycle of Mn^(4+)/Mn^(3+)and surface hydroxyl group of the fixed MnO_(2) was proved to be responsible for the activation of *** work provides a new avenue for developing fixed metal oxides for sustainable water treatment.

关键词： Redox strategy Manganese oxides Fixed catalyst Peroxymonosulfate PPCPs

Emerging hierarchical mesoporous materials of covalent organic frameworks

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Science China Chemistry 2024年第9期67卷 2796-2802页

作者： Lingyan Huang Wenda Li Hongyi Zhang Shanzhe Ke Hao Chen Jianwei Fu Chengbin Jing Jiangong Cheng Shaohua Liu state key laboratory of Precision Spectroscopy/engineering Research Center of Nanophotonics&Advanced Instrument(Ministry of Education) School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China School of Materials Science and engineering Zhengzhou UniversityZhengzhou 450052China state key lab of Transducer Technology Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China

Benefiting from abundant exposed active sites,minimized diffusion resistance of guest molecules,facilitated mass transfer process and enhanced storage capacity,covalent organic frameworks(COFs)have gained widespread scientific attention[1–4].Further construction of mesopores regarding pore engineering(pore size,pore geometry,pore volume,and framework compositions)in COFs can improve mass transport,accessibility as well as size-selectivity of the special guest moieties,thus exhibiting potential in catalysis,energy storage and separation and so on[5,6].

关键词： gained catalysis separation