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Bimetallic anchoring catalysis for C–H and C–C activation

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Science China Chemistry 2021年第11期64卷 1923-1937页

作者： Jiang-Fei li Yu-xin luan Mengchun ye State Key laboratory and Institute of Elemento-Organic Chemistry College of ChemistryFrontiers Science Center for New Organic MatterNankai UniversityTianjin300071China

Following the age of directing group,anchoring catalysis starts coming to the center of the *** from the directinggroup strategy that needs a preinstalled directing group in substrates,anchoring catalysis relies on a reversible interaction between a substrate and a catalyst,which then directs metal to activate inert chemical *** reversible directing effect not only generates good site-and stereo-selectivity as traditional directing groups do but also eliminates the requirement of stoichiometric amounts of directing *** variously reported anchoring catalysis,coordinative bimetallic anchoring catalysis in general displays superior reactivity than others because coordinative bonding not only affords strong interaction of catalysts with substrates but also displays good compatibility with substrates and reaction *** recent years,big progress has been achieved for coordinative bimetallic anchoring *** review gave a detailed summary of this field,including catalyst development,catalyst types,reaction types and reaction mechanisms.

关键词： C–H activation C–C activation bimetallic catalysis enantioselective anchoring catalysis

Double-plume lagrangian particle tracking model and its application in deep water oil spill

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Journal of Hydrodynamics 2023年第3期35卷 571-581页

作者： xin-wei ye Xiao-jing Niu Jian Jiang State Key laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing100084China

Due to the density stratification of sea water,the dispersed oil droplets and gas bubbles with small diameters,as well as the dissolved components,may remain in some specific *** double-plume lagrangian particle tracking model for bubbly plumes in vertical density stratified environments is improved and applied to predict the underwater pollutants in a *** model considers the different properties and dissolution processes of components in crude oil and focuses on their behavior and stratification differences in the *** crude oil components are divided into several groups and the dissolution of oil and gas is also *** model is applied to simulate the“Deepwater Horizon”oil spill accident in the Gulf of Mexico in *** results show several enrichment layers of oil and gas at different depth and the differences in concentration between components,which corresponds to the distribution of petroleum pollutants in the in-situ observation.

关键词： Oil spill double-plume model lagrangian particle tracking the Gulf of Mexico

Effect of particle micro-structure on the electrochemical properties of liNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode material

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International Journal of Minerals,Metallurgy and Materials 2022年第8期29卷 1618-1626页

作者： Zexun Tang Hongqi ye xin Ma Kai Han Hunan Provincial Key laboratory of Efficient and Clean Utilization of Manganese Resources College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China Cathode Material Research&Development Department Soundon New Energy Technology Co.Ltd.Xiangtan 411100China

Ni-rich layered material is a kind of high-capacity cathode to meet the requirement of electric *** for the typical liNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) material,the particle formation is significant for electrochemical properties of the *** this work,the structure,morphology,and electrochemical performance of liNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) secondary particles and single crystals were systematically studied.A lower Ni^(2+)/Ni^(3+)molar ratio of 0.66 and a lower residual alkali content of 0.228wt%were achieved on the surface of the single *** addition,the single crystals showed a discharge capacity of 191.6 mAh/g at 0.2 C(~12 mAh/g lower than that of the secondary particles)and enhanced the electrochemical stability,especially when cycled at 50℃ and in a wider electrochemical window(between 3.0 and 4.4 V ***+/li).The liNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) secondary particles were suitable for applications requiring high specific capacity,whereas single crystals exhibited better stability,indicating that they are more suitable for use in long life requested devices.

关键词： Ni-rich layered materials single crystal cathode micro-structure lithium-ion battery

Truncation and aliasing errors for Whittaker-Kotelnikov-Shannon sampling expansion

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Applied Mathematics(A Journal of Chinese Universities) 2012年第4期27卷 412-418页

作者： ye Pei-xin SONG Zhan-jie School of Mathematics and lPMC Nankai UniversityTianjin 300071China Department of Mathematics School of ScienceTianjin UniversityTianjin 300072China

let B^pΩ, 1 ≤ p 〈 ∞, be the space of all bounded functions from lp（R） which can be extended to entire functions of exponential type Ω. The uniform error bounds for truncated Whittaker-Kotelnikov-Shannon series based on local sampling are derived for functions f ∈ B^pΩ without decay assumption at infinity. Then the optimal bounds of the aliasing error and truncation error of Whittaker-Kotelnikov-Shannon expansion for non-bandlimited functions from Sobolev classes l/（Wp（R）） are determined up to a logarithmic factor.

关键词： Whittaker-Kotelnikov-Shannon theorem localized sampling truncation error aliasing error,Sobolev class.

Hierarchical cluster-tendency analysis of the group structure in the foreign exchange market

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Frontiers of physics 2013年第4期8卷 451-460页

作者： xin-ye Wu Zhi-Gang Zheng Department of Physics and the Beijing-Hong Kong Singapore Joint Center for Nonlinear and Complex Systems Beijing Normal University Beijing 100875 China

A hierarchical cluster-tendency （HCT） method in analyzing the group structure of networks of the global foreign exchange （FX） market is proposed by combining the advantages of both the minimal spanning tree （MST） and the hierarchical tree （HT）. Fifty currencies of the top 50 World GDP in 2010 according to World Bank＇s database are chosen as the underlying system. By using the HCT method, all nodes in the FX market network can be ＂colored＂ and distinguished. We reveal that the FX networks can be divided into two groups, i.e., the Asia-Pacific group and the Pan-European group. The results given by the hierarchical cluster-tendency method agree well with the formerly observed geographical aggregation behavior in the FX market. Moreover, an oil-resource aggregation phenomenon is discovered by using our method. We find that gold could be a better numeraire for the weekly-frequency FX data.

关键词： foreign-exchange market hiergrchical cluster-tendency method hierarchical tree,minimum spanning tree

Phosphorus recovery from wastewater by struvite crystallization:Property of aggregates

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Journal of Environmental Sciences 2014年第5期26卷 991-1000页

作者： Zhilong ye Yin Shen xin ye Zhaoji Zhang Shaohua Chen Jianwen Shi Key laboratory of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences

Struvite crystallization is a promising method to remove and recover phosphorus from wastewater to ease both the scarcity of phosphorus rock resources and water eutrophication worldwide. To date, although various kinds of reactor systems have been developed, supporting methods are required to control the stmvite fines flushing out of the reactors. As an intrinsic property, aggregation is normally disregarded in the struvite crystallization process, although it is the key factor in final particle size and therefore guarantees phosphorus recovery efficiency. The present study developed a method to analyze the characteristics of struvite aggregates using fractal geometry, and the influence of operational parameters on struvite aggregation was evaluated. Due to its typical orthorhombic molecular structure, struvite particles are prone to crystallize into needle or rod shapes, and aggregate at the comers or edges of crystals. The determined fractal dimension （Dpf） of struvite aggregates was 1.52-1.31, with the corresponding range of equivalent diameter （d0.5） at 295.9-85.4 Ixm. Aggregates formed in relatively low phosphorus concentrations （3.0-5.0 mmol/l） and mildly alkaline conditions （pH 9.0-9.5） displayed relatively compact structures, large aggregate sizes and high aggregation strength. Increasing pH values led to continuous decrease of aggregate sizes, while the variation of Dpf was insignificant. As to the aggregate evolution, fast growth in a short time followed by a long steady stage was observed.

关键词： struvite aggregate fractal dimension phosphorus recovery image analysis

New Family of 3-DOF UP-Equivalent Parallel Mechanisms with High Rotational Capability

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Chinese Journal of Mechanical Engineering 2018年第1期31卷 66-77页

作者： Wei ye Qin-Chuan li xin-Xue Chai Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech University

Parallel mechanisms(PMs) having the same motion characteristic with a UP kinematic chain(U denotes a universal joint, and P denotes a prismatic joint) are called UP-equivalent PMs. They can be used in many applications, such as machining and milling. However, the existing UP-equivalent PMs suffer from the disadvantages of strict assembly requirements and limited rotational capability. Type synthesis of UP-equivalent PMs with high rotational capability is *** special 2 R1 T motion is briefly discussed and the fact that the parallel module of the Exechon robot is not a UP-equivalent PM is disclosed. Using the lie group theory, the kinematic bonds of limb chains and their mechanical generators are presented. Structural conditions for constructing such UP-equivalent PMs are proposed,which results in numerous new architectures of UP-equivalent PMs. The high rotational capability of the synthesized mechanisms is illustrated by an example. The advantages of no strict assembly requirements and high rotational capability of the newly developed PMs will facilitate their applications in the manufacturing industry.

关键词： Parallel mechanism Group theory Type synthesis High rotational capability

Enhanced sampling based on slow variables of trajectory mapping

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Science China(Physics,Mechanics & Astronomy) 2019年第6期62卷 81-86页

作者： ChuanBiao Zhang FangFu ye Ming li xin Zhou School of Physical Sciences University of Chinese Academy of Sciences Department of Physics and Electronic Engineering Heze University Institute of Physics Chinese Academy of Sciences

Most current enhanced sampling(ES) algorithms attempt to bias a potential energy surface based on preset slow collective variables to improve simulation efficiency. However, due to difficulty in obtaining slow variables in complex molecular systems,approximate slow variables are usually applied in ES, which often fail to achieve the expected high efficiency and sufficient accuracy when reconstructing equilibrium properties. In this paper, we demonstrate that the trajectory mapping(TM) technique has the potential to provide the required slow variables for ES. We illustrate the application of a typical ES algorithm(metadynamics)based on the slow variables constructed from the TM in a hairpin peptide system. In this system, both the equilibrium properties and slow dynamics are accurately obtained within approximately two to three orders of magnitude shorter simulation time than in regular molecular dynamics simulation.

关键词： molecular dynamics trajectory map metadynamics

Environment map building and localization for robot navigation based on image sequences

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 489-499页

作者： ye-hu SHEN Ji-lin lIU xin DU Department of Information Science and Electronic Engineering Zhejiang University Hangzhou 310027 China

SlAM is one of the most important components in robot navigation. A SlAM algorithm based on image sequences captured by a single digital camera is proposed in this paper. By this algorithm, SIFT feature points are selected and matched between image pairs sequentially. After three images have been captured, the environment’s 3D map and the camera’s positions are initialized based on matched feature points and intrinsic parameters of the camera. A robust method is applied to estimate the position and orientation of the camera in the forthcoming images. Finally, a robust adaptive bundle adjustment algorithm is adopted to optimize the environment’s 3D map and the camera’s positions simultaneously. Results of quantitative and qualitative experiments show that our algorithm can reconstruct the environment and localize the camera accurately and efficiently.

关键词： Monocular vision Digital elevation map (DEM) SIFT Robust adaptive bundle adiustment SlAM algorithm