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Defect engineering on constructing surface active sites in catalysts for environment and energy applications

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Frontiers of Chemical Science and Engineering 2024年第7期18卷 11-32页

作者： Yawen Cai Baowei Hu xiangke wang School of Life Science Shaoxing UniversityShaoxing 312000China College of Environmental Science and Engineering North China Electric Power UniversityBeijing 102206China

The precise engineering of surface active sites is deemed as an efficient protocol for regulating surfaces and catalytic properties of *** engineering is the most feasible option to modulate the surface active sites of *** specific active sites on the catalyst allows precise modulation of its electronic structure and physicochemical ***,we outlined the engineering of several types of defects,including vacancy defects,void defects,dopant-related defects,and defect-based single atomic *** overview of progress in fabricating structural defects on catalysts via de novo synthesis or post-synthetic modification was ***,the applications of the well-designed defective catalysts in energy conversion and environmental remediation were carefully ***,current challenges in the precise construction of active defect sites on the catalyst and future perspectives for the development directions of precisely controlled synthesis of defective catalysts were also proposed.

关键词： defect engineering vacancy void defects doping single atomic sites

Vector Field Based Sliding Mode Control of Curved Path Following for Miniature Unmanned Aerial Vehicles in Winds

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Journal of Systems Science & Complexity 2018年第1期31卷 302-324页

作者： wang Yajing wang xiangke ZHAO Shulong SHEN Lincheng College of Mechatronic Engineering and Automation National University of Defense Technology

In this paper, a curved path following control algorithm for miniature unmanned aerial vehicles（UAVs） in winds with constant speed and altitude is developed. Different to the widely considered line or orbit following, the curved path to be followed is defined in terms of the arc-length parameter, which can be straight lines, orbits, B-splines or any other curves provided that they are smooth. The proposed path following control algorithm, named by VF-SMC, is combining the vector field（VF） strategy with the sliding mode control（SMC） method. It is proven that the designed algorithm guarantees the tracking errors to be a bounded ball in the presence of winds, with the aid of the Lyapunov method and the BIBO stability. The algorithm is validated both in Matlab-based simulations and high-fidelity semi-physical simulations. In Matlab-based simulations, the proposed algorithm is verified for straight lines, orbits and B-splines to show its wide usage in different *** high-fidelity semi-physical simulation system is composed of actual autopilot controller, ground station and X-Plane flight simulator in-loop. In semi-physical simulations, the proposed algorithm is verified for B-spline path following under various gain parameters and wind conditions *** experiments show the accuracy in curved path following and the excellent robustness to wind disturbances of the proposed algorithm.

关键词： Curved path following miniature UAVs sliding mode control vector field wind disturbance

Formation flight of fixed-wing UAV swarms:A group-based hierarchical approach

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Chinese Journal of Aeronautics 2021年第2期34卷 504-515页

作者： Hao CHEN xiangke wang Lincheng SHEN Yirui CONG College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China

This paper investigates a formation control problem of fixed-wing Unmanned Aerial Vehicle(UAV) swarms. A group-based hierarchical architecture is established among the UAVs, which decomposes all the UAVs into several distinct and non-overlapping groups. In each group, the UAVs form hierarchies with one UAV selected as the group leader. All group leaders execute coordinated path following to cooperatively handle the mission process among different groups, and the remaining followers track their direct leaders to achieve the inner-group coordination. More specifically, for a group leader, a virtual target moving along its desired path is assigned for the UAV, and an updating law is proposed to coordinate all the group leaders’ virtual targets;for a follower UAV, the distributed leader-following formation control law is proposed to make the follower’s heading angle coincide with its direct leader, while keeping the desired relative position with respect to its direct leader. The proposed control law guarantees the globally asymptotic stability of the whole closed-loop swarm system under the control input constraints of fixed-wing UAVs. Theoretical proofs and numerical simulations are provided, which corroborate the effectiveness of the proposed method.

关键词： Control input constraints Coordinated path following Formation control Leader-following control Unmanned aerial vehicles swarms

Poly(amidoxime)-reduced graphene oxide composites as adsorbents for the enrichment of uranium from seawater

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Science China Chemistry 2014年第11期57卷 1449-1458页

作者： SHAO DaDong LI JiaXing wang xiangke School of Environment and Chemical Engineering North China Electric Power University School for Radiological and Interdisciplinary Sciences Soochow University Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions

The development of efficient materials for high extraction of uranium(UO22+) from seawater is critical for nuclear energy. Poly(amidoxime)-reduced graphene oxide(PAO/rGO) composites with excellent adsorption capability for UO22+ were synthesized by in situ polymerization of acrylonitrile monomers on GO surfaces, followed by amidoximation treatment with hydroxylamine. The adsorption capacities of PAO/rGO composites for UO22+ reached as high as 872 mg/g at pH 4.0. The excellent tolerance of these composites for high salinity and their regeneration-reuse properties can be applied in the nuclear-fuel industry by high extraction of trace UO22+ ions from seawater.

关键词： uranium amidoxime graphene acrylonitrile adsorption

Microstructures and speciation of radionuclides in natural environment studied by advanced spectroscopy and theoretical calculation

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Science China Chemistry 2017年第9期60卷 1149-1152页

作者： Xiangxue wang Shujun Yu Zhongshan Chen Yushan Zhao Jie Jin xiangke wang School of Environment and Chemical Engineering North China Electric Power UniversityBeijing 102206China

The environmental behavior of radionuclides is mainly dependent on their speciation and microstructures at solid *** speciation and microstructures of radionuclides at molecular level can be achieved from advanced spectroscopy techniques and theoretical *** this perspective,we give a brief introduction of the advanced X-ray absorption fine structure(XAFS) technique and theoretical calculation in the analysis of the speciation and microstructures of radionuclides in the natural environment,which is crucial to evaluate the physicochemical behavior of radionuclides in the environment.

关键词： radionuclides speciation microtructures spectroscopy technique theoretical calculation

Reductive immobilization of Re(VⅡ)by graphene modified nanoscale zero-valent iron particles using a plasma technique

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Science China Chemistry 2016年第1期59卷 150-158页

作者： Jie Li Changlun Chen Rui Zhang xiangke wang Institute of Plasma Physics Chinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions Soochow UniversitySuzhou 215123China School for Radiological and Interdisciplinary Sciences(RAD-X) Soochow UniversitySuzhou 215123China Faculty of Engineering King Abdulaziz UniversityJeddah 21589Saudi Arabia

Technetium-99(~99Tc),largely produced by nuclear fission of ~235U or ~239Pu,is a component of radioactive *** study focused on a remediation strategy for the reduction of pertechnetate(Tc O_4^-)by studying its chemical analogue rhenium(Re(VⅡ))to avoid the complication of directly working with radioactive *** zero-valent iron particles supported on graphene(NZVI/r GOs)from GOs-bound Fe ions were prepared by using a H_2/Ar plasma technique and were applied in the reductive immobilization of perrhenate(Re O_4^-).The experimental results demonstrated that NZVI/r GOs could efficiently remove Re from the aqueous solution,with enhanced reactivity,improved kinetics(50 min to reach equilibrium)and excellent removal capacity(85.77 mg/g).The results of X-ray photoelectron spectroscopy analysis showed that the mechanisms of Re immobilization by NZVI/r GOs included adsorption and reduction,which are significant to the prediction and estimation of the effectiveness of reductive Tc O_4^- by NZVI/r GOs in the natural environment.

关键词： reductive immobilization Re(VII) NZVI/r GOs plasma technique

Americium/lanthanide separation enabled by a distinct polyoxometalate cluster

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Science China Chemistry 2024年第1期67卷 312-313页

作者： Hui Yang xiangke wang Shengqian Ma College of Environmental Science and Engineering North China Electric Power UniversityBeijing 102206P.R.China Department of Chemistry University of North TexasDentonTexas 76201United States

Nuclear energy is viewed as a low carbon-emission electricity-generating technology with high-energy density,which has attracted extensive attention and shown broad development prospects[1].However,to ensure sustainability and cleanability in the development of nuclear energy,one crucial challenge is to exploit efficient and economical technologies to simultaneously recover fissionable nuclides from nuclear waste and separate long-lived toxic fission products[2].

关键词： lanthanide separation cluster

Simultaneous removal of uranium and humic acid by cyclodextrin modified graphene oxide nanosheets

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Science China Chemistry 2014年第9期57卷 1291-1299页

作者： SONG WenCheng SHAO DaDong LU SongSheng wang xiangke School of Nuclear Science and Technology University of Science and Technology of China Institute of Plasma Physics Chinese Academy of Sciences New Star Institute of Applied Technology

Cyclodextrin-modified graphene oxide nanosheets(denoted as CD/GO) were synthesized by an in-situ polymerization method and characterized by as well as Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and potentiometric acid-base titration. The characterization results indicated that CD was successfully grafted onto GO surfaces by forming a chemical bond. Mutual effects on the simultaneous removal of hexavalent uranium and humic acid by CD/GO from aqueous solution were investigated. The results indicated that U(VI) and humic acid(HA) sorption on CD/GO were greatly affected by pH and ionic strength. The presence of HA enhanced U(VI) sorption at low pH and reduced U(VI) sorption at high pH, whereas the presence of U(VI) enhanced HA sorption. The surface adsorbed HA acted as a "bridge" between U(VI) and CD/GO, and formed strong inner-sphere surface complexes with U(VI). Sorption isotherms of U(VI) or HA on CD/GO could be well fitted by the Langmuir model. This work highlights that CD/GO can be used as a promising material in the enrichment of U(VI) and HA from wastewater in U(VI) and humic substances obtained by environmental pollution cleanup.

关键词： graphene oxide uranium humic acid cyclodextrin simultaneous sorption

Gaussian Process Based Modeling and Control of Affine Systems with Control Saturation Constraints

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Complex System Modeling and Simulation 2023年第3期3卷 252-260页

作者： Shulong Zhao Qipeng wang Jiayi Zheng xiangke wang College of Intelligence Science and Technology National University of Defense TechnologyChangsha 410073China

Model-based methods require an accurate dynamic model to design the ***,the hydraulic parameters of nonlinear systems,complex friction,or actuator dynamics make it challenging to obtain accurate *** this case,using the input-output data of the system to learn a dynamic model is an alternative ***,we propose a dynamic model based on the Gaussian process(GP)to construct systems with control *** GP provides a measure of model confidence,it can deal with ***,most GP-based literature considers model uncertainty but does not consider the effect of constraints on inputs in closed-loop *** auxiliary system is developed to deal with the influence of the saturation constraints of ***,we relax the nonsingular assumption of the control coefficients to construct the *** numerical results verify the rationality of the proposed approach and compare it with similar methods.

关键词： Gaussian process(GP) auxiliary system credibility constraints input