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Singularity analysis and avoidance for an SSRMS-type reconfigurable space manipulator with a non-spherical wrist and two lockable passive telescopic links

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Chinese Journal of Aeronautics 2024年第8期37卷 435-459页

作者： Zhiyuan ZHAO Xiaohang yang Yuntao li Zichun XU Jingdong ZHAO hong liu State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China

This study focuses on addressing kinematic singularity analysis and avoidance issues for a space station remote manipulator system(SSRMS)-type reconfigurable space *** manipulator is equipped with a non-spherical wrist and two lockable passive telescopic links(LPTLs),which enable it to have both active revolute and passive prismatic joints and operate in two distinct *** begin with the kinematic singularity analysis,the study derives the differential kinematic equations for the manipulator and identifies the dominant Jacobian matrix that causes ***,an in-depth analysis of singularities from multiple perspectives is ***,a kinematic singularity map method is proposed to capture the distribution of singularities within the reachable ***,the influence of the two LPTLs on singularities is thoroughly ***,a new method based on the matrix rank equivalence principle is introduced to determine singularity conditions,enabling the identification of all the singular configurations for the SSRMS-type reconfigurable ***,this method significantly reduces computational complexity,and the singularity conditions obtained have more concise *** the singularity avoidance problem,a novel method is developed,which simultaneously addresses the requirements of real-time performance,high precision,and the avoidance of both kinematic singularities and joint limit *** from these excellent properties,the proposed method can effectively resolve the singularity issues encountered separately by the SSRMS-type reconfigurable manipulator in its two operational *** typical simulations validate the utility of all the proposed methods.

关键词： Reconfigurable space manipulator Redundant manipulator Kinematics Singularity analysis Singularity avoidance

Clinical effect of laparoscopic radical resection of colorectal cancer based on propensity score matching

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World Journal of Gastrointestinal Surgery 2024年第1期16卷 124-133页

作者： yang liu Xian-Xue Wang Yu-lin li Wen-Tao he hong li Hua Chen Department of General Surgery Changde HospitalXiangya School of MedicineCentral South University(The First People’s Hospital of Changde City)Changde 415000Hunan ProvinceChina Department of Anesthesiology Changde HospitalXiangya School of MedicineCentral South University(The First People’s Hospital of Changde City)Changde 415000Hunan ProvinceChina

BACKGROUND The incidence of colorectal cancer(CRC)is increasing *** radical resection of CRC is a minimally invasive procedure preferred in clinical *** To investigate the clinical effect of laparoscopic radical resection of CRC on the basis of propensity score matching(PSM).METHODS The clinical data of 100 patients who received inpatient treatment for CRC at Changde Hospital,Xiangya School of Medicine,Central South University(The First People’s Hospital of Changde City)were analyzed *** control group included patients who underwent open surgery(n=43),and those who underwent laparoscopic surgery formed the observation group(n=57).The baseline information of both groups was equipoised using 1×1 *** in the perioperative parameters,inflammatory response,immune function,degree of pain,and physical status between the groups were *** Thirty patients from both groups were successfully *** PSM,baseline data showed no statistically significant differences between the groups:(1)Periop-erative parameters:The observation group had a longer surgery time,less intra-operative blood loss,earlier first ambulation and first anal exhaust times,and shorter gastric tube indwelling time than the control group;(2)Inflammatory response:24 h after surgery,the levels of interleukin-6(IL-6),C-reactive protein(CRP),and tumor necrosis factor-α(TNF-α)between groups were higher than ***-6,CRP,and TNF-αlevels in the observation group were lower than in the control group;(3)Immune function:At 24 h after surgery,counts of CD4-positive T-lymphocytes(CD4+)and CD4+/CD8-positive T-lymphocytes(CD8+)in both groups were lower than those before surgery,whereas CD8+was higher than that before *** 24 h after surgery,both CD4+counts and CD4+/CD8+in the observation group were higher than those in the control group,whereas CD8+counts were lower;(4)Degree of pain:The visual analog scale scores in the observation gro

关键词： Colorectal cancer Laparoscopic Open surgery Inflammatory reaction Immune function Propensity score

Enhanced hydrogen evolution reaction in FePt film with remanence due to decrease in domain walls

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Rare Metals 2024年第3期43卷 1108-1115页

作者： hong hong Dong-Xue liu Jun li Jun-Ming li li-Qian Wu Bo yang Qing-Qi Cao Dun-Hui Wang National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructuresJiangsu Provincial Key Laboratory for NanotechnologySchool of PhysicsNanjing UniversityNanjing210093China Hangzhou Dianzi University Hangzhou310018China Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang110819China

As an effective strategy to improve the properties of electrocatalysts,magnetic field-assisted electrocatalytic water splitting has attracted increasing attention ***,the corresponding enhancements mostly depend on the exertion of an external magnetic field during electrochemical reactions,which results in a high cost of industrial production,and makes the magnetic field manipulation of electrocatalysis become a challenging *** this work,instead of the external magnetic field,a bias magnetic field is self-supplied by the remanence state of a ferromagnetic electrocatalyst of *** to the assistance of this bias magnetic field,the FePt film in the remanence state shows the overpotential of 229 mV during hydrogen evolution reaction,which is much lower than that in its demagnetization state(283 mV).Our findings demonstrate that the remanence in ferromagnetic electrocatalysts can improve the catalytic performance,which is attributed to the decrease in domain walls.

关键词： Remanence Magnetic domains Electrocatalysis Hydrogen evolution reaction(heR)

What is the Role of Gravity,Turbulence and Magnetic Fields in High-mass Star Formation Clouds?

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Research in Astronomy and Astrophysics 2024年第6期24卷 21-27页

作者： An-Xu Luo hong-li liu Guang-Xing li Sirong Pan Dong-Ting yang School of Physics and Astronomy Yunnan UniversityKunming 650091China South-Western Institute for Astronomy Research Yunnan UniversityKunming 650500China

To explore the potential role of gravity,turbulence and magnetic fields in high-mass star formation in molecular clouds,this study revisits the velocity dispersion–size(σ–L)and density–size(ρ–L)scalings and the associated turbulent energy spectrum using an extensive data *** sample includes various hierarchical density structures in high-mass star formation clouds,across scales of 0.01–100 *** observeσ∝L^(0.26)andρ∝L^(-1.54)scalings,converging toward a virial equilibrium state.A nearly flat virial parameter–mass(α_(vir)-M)distribution is seen across all density scales,withα_(vir)values centered around unity,suggesting a global equilibrium maintained by the interplay between gravity and turbulence across multiple *** turbulent energy spectrum(E(k))analysis,based on theσ–L andρ–L scalings,yields a characteristic E(k)∝k^(-1.52).These findings indicate the potential significance of gravity,turbulence,and possibly magnetic fields in regulating dynamics of molecular clouds and high-mass star formation therein.

关键词： ISM:clouds stars:formation stars:kinematics and dynamics

Single Ti atoms coupled with Ti-O clusters enable low temperature hydrogen cycling by sodium alanate

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Rare Metals 2024年第6期43卷 2671-2681页

作者： Zhuang-he Ren Xin Zhang Wen-Xuan Zhang Zhen-Guo Huang li-Mei yang Ya-Xiong yang Zheng-Long li Juan li Wen-Ping Sun Ming-Xia Gao hong-Ge Pan Yong-Feng liu State Key Laboratory of Silicon and Advanced Semiconductor Materials Zhejiang UniversityHangzhou 310027China School of Materials Science and Engineering Zhejiang UniversityHangzhou 310058China School of Civil&Environmental Engineering.University of Technology Sydney Sydney2007 NSWAustralia Institute of Science and Technology for New Energy Xi'an Technological UniversityXi'an 710021China College of Materials Science and Engineering Zhejiang University of TechnologyHangzhou 310014China

Ti-based catalysts are known to improve the hydrogen storage performance of NaAlH4by facilitating the dissociation/recombination of H-H and Al-H *** catalytic activity of metallic Ti species strongly depends on its particle size and *** clusters and even single atoms are therefore highly desirable,but their controllable fabrication has been highly *** rein,we demonstrate a novel facile sonochemical synthesis of a Ti-O clusters featuring single Ti atom catalyst at room *** reducing TiCl_(4)by MgBu_(2)with ultrasound instead of heating as driving force,numerous single Ti atoms coupled with Ti-O clusters with Ti loading on graphene(Ti_(1)/Ti-O@G)up to 22.6 wt%have been successfully *** prepared Ti_(1)/Ti-O@G contributes high reactivity and superior catalytic activity,therefore enabling full dehydrogenation of NaAlH_(4)at 80℃in thermogravimetric mode and re-hydrogenation at 30℃and 10 MPa with 4.9 wt% H_(2).This fact indicates for the first time that single Ti atom catalyst with high loading is highly effective in catalyzing hydrogen cycling of NaAlH4at remarkably reduced temperatures.

关键词： Hydrogen storage Nanocatalysis Transition metals Single Ti atoms NaAlH_(4)

Intense and Superflat White Laser with 700-nm 3-dB Bandwidth and 1-mJ Pulse Energy Enabling Single-Shot Subpicosecond Pulse Laser Spectroscopy

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Research 2024年第2期6卷 319-327页

作者： lihong hong Haiyao yang liqiang liu Mingzhou li Yuanyuan liu Baoqin Chen Huakang Yu Wenbo Ju Zhi-Yuan li School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510641China State Key Laboratory of Luminescent Materials and Devices South China University of TechnologyGuangzhou 510640China

An optical spectrometer is a basic spectral instrument that probes microscopic physical and chemical properties of macroscopic objects but generally suffers from difficulty in broadband time-resolved *** this work,we report the creation of ultrabroadband white-light laser with a 3-dB bandwidth covering 385 to 1,080 nm,pulse energy of 1.07 mJ,and pulse duration of several hundred femtoseconds by passing 3-mJ pulse energy,50-fs pulse duration Ti:Sapphire pulse laser through a cascaded fused silica plate and chirped periodically poled lithium niobate *** utilize this unprecedented superflat,ultrabroadband,and intense femtosecond laser light source to build a single-shot(i.e.,single-pulse)subpicosecond pulse laser ultraviolet-visible-near-infrared spectrometer and successfully measure various atomic and molecular absorption *** single-shot ultrafast spectrometer may open up a frontier to monitor simultaneously the ultrafast dynamics of multiple physical and chemical processes in various microscopic systems.

关键词： Pulse utilize frontier

Prediction for permeability index of blast furnace based on VMD-PSO-BP model

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Journal of Iron and Steel Research International 2024年第3期31卷 573-583页

作者： Xiao-jie liu Yu-jie Zhang Xin li Zhi-feng Zhang hong-yang li Ran liu Shu-jun Chen School of Metallurgy and Energy North China University of Science and TechnologyTangshan 063210HebeiChina Chengde Branch HBIS Group Co.Ltd.Chengde 067000HebeiChina

The permeability index is one of the important production indicators to monitor the operation of blast *** is crucial to grasp the trends of changes in the new permeability index in *** the complex vibration spectrum of the permeability index,a prediction model of the permeability index based on the VMD-PSO-BP(variational mode decomposition-particle swarm optimization-back propagation)method was ***,the key factors that affect the permeability index of blast furnace were studied from multiple ***,the permeability index was divided into multiple sub-modes based on the difference of frequency bands by the VMD algorithm,and a PSO-BP prediction model was established for each ***,the prediction results of each sub-mode were summed to obtain the final *** results show that the composite prediction accuracy by using the VMD algorithm is 3%higher than that of the traditional prediction method,which has better applicability.

关键词： Big data-Blast furnace Air permeability Variational mode decomposition Particle swarm optimization Back propagation Model prediction

Regulating Actuations and Shapes of liquid Crystal Elastomers through Combining Dynamic Covalent Bonds with Cooling-Rate-Mediated Control

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Chinese Journal of Polymer Science 2024年第10期42卷 1442-1448,I0008页

作者： Ya-Wen liu Huan liang hong-Tu Xu En-Jian he Zhi-Jun yang Yi-Xuan Wang Yen Wei Zhen li Yan Ji The Key Laboratory of Bioorganic Phosphorus Chemistry&Chemical Biology(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing100084China Advanced Materials and Energy Center Academy of Aerospace Science and InnovationBeijing100088China

Realizing multiple locked shapes in pre-oriented liquid crystal elastomers(LCEs)is highly desired for diversifying deformations and enhancing ***,conventional LCEs only deform between two shapes for each actuation cycle upon liquid crystal-isotropic phase transitions induced by external ***,we propose to regulate the actuation modes and the locked shapes of a pre-orientated epoxy LCE by combining dynamic covalent bonds with cooling-rate-mediated *** actuation modes can be adjusted on demand by exchange reactions of dynamic covalent *** from the established actuation modes,such as elongation,bending,and spiraling,the epoxy LCE displays varied locked shapes at room temperature under different cooling *** mediums are utilized to control the cooling rate,including water,silicone oil,and copper *** approach provides a novel way for regulating the actuation modes and locked shapes of cuttingedge intelligent devices.

关键词： liquid crystal elastomer Epoxy Dynamic covalent bond Vitrimer Cooling rate

Effects of zero-valent iron added in the flooding or drainage process on cadmium immobilization in an acid paddy soil

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Journal of Environmental Sciences 2024年第4期138卷 19-31页

作者： Hanbing Meng Shiwen Hu Zebin hong Wenting Chi Guojun Chen Kuan Cheng QiWang Tongxu liu Fangbai li Kexue liu yang yang Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640China National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and ManagementInstitute of Eco-environmental and Soil SciencesGuangdong Academy of SciencesGuangzhou 510650China School of Resources and Planning Guangzhou Xinhua UniversityGuangzhou 510310China University of Chinese Academy of Sciences Beijing 100049China

Zero-valent iron(ZVI)is a promising material for the remediation of Cd-contaminated paddy ***,the effects of ZVI added during flooding or drainage processes on cadmium(Cd)retention remain ***,Cd-contaminated paddy soil was incubated for 40days of flooding and then for 15 days of drainage,and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were *** addition of ZVI to the flooding process was more conducive to Cd *** potential available Cd was detected by adding ZVI before flooding,which may be due to the increase in paddy soil pH and newly formed secondary Fe ***,the reductive dissolution of Fe minerals promoted the release of soil colloids,thereby increasing significantly the surface sites and causing Cd ***,the addition of ZVI before flooding played a vital role in Cd retention after soil *** contrast,the addition of ZVI in the drainage phase was not conducive to Cd retention,which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil *** findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.

关键词： Paddy soil Zero-valent iron Cadmium Flooding and drainage Remediation