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A calibration and compensation method for an industrial robot with high accuracy harmonic reducers

Science China(Technological Sciences) 2024年第3期67卷 725-739页

作者： ZHAO Yiyang LIU xun CAO JiaBin LIU JinYu xu yan yan WeiXin School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China College of Computer and Control Engineering Northeast Forestry UniversityHarbin 150040China

Industrial serial robots need high stiffness to keep absolute pose accuracy and meet the requirements in practical applications. However, the weak stiffness feature of robot joints and the payloads affected on robot end-effector, which will also increase the pose error of robot. Especially, the existing calibration methods often consider under no-payload condition without discussing the payload state. In this paper, we report a new industrial serial robot composed by a new harmonic reducer: Model-Y, based on high accuracy and high stiffness, and a kinematic parameter calibration algorithm which is based on a harmonic reducer forcedeformation model. To decrease the accuracy effects of payload, an iterative calibration method for kinematic parameters with payload situation was proposed. Simulation and experiments are conducted to verify the effectiveness of the proposed calibration method using the self-developed industrial serial robot. The results show a remarkably improved accuracy in absolute position and orientation with the robot's payload range. The position mean error has 70% decreased to 0.1 mm and the orientation mean error diminished to less than 0.01° after calibration with compensation. Additionally, online linear and circular tests are carried out to evaluate the position error of the robot during large-scale spatial and low-speed continuous movement. The accuracy is consistent with the previous calibration results, indicating the effectiveness and advantages of the proposed strategy in this article.

关键词： industrial serial robot Model-Y harmonic calibration stiffness model online compensation

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Enhanced Flexoelectric Response from Functionally Gradient Electrets Undergoing Crumpling Deformation

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Acta Mechanica Solida Sinica 2024年第4期37卷 541-554页

作者： Jianhua Ma Jinrui xu jun Li Binglei Wang Department of Engineering Mechanics Shandong UniversityJinan250061China

Non-uniform deformation of the dielectric subjected to external forces can induce the flexoelectric effect, a phenomenon that couples electrical polarization to strain gradients. However, limited by the size effects, flexoelectricity is not significant at the macroscale and only becomes catchable at the microscale and nanoscale. In recent work, we obtained a considerable flexoelectric-like response by crumpling the dielectric embedded with charges, i.e., the electret, which significantly improved the flexoelectric effect at the macroscale. In this work, we further optimize the macroscopic performance of the flexoelectric response by applying gradient treatment to the electret films. Specifically, we analytically derive the electromechanical coupling of crumpled electret films with gradients of different thicknesses, charge densities, and Young’s moduli as key design variables. It is shown that the gradient-oriented electret film can be tuned to nearly five times that of a uniform electret film.

关键词： Functionally gradient electret Size effects Crumpling Flexoelectric-like response

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Numerical simulation on directional solidification and heat treatment processes of turbine blades

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China Foundry 2024年第5期21卷 476-490页

作者： Ye-yuan Hu Ju-huai Ma Qing-yan xu School of Materials Science and Engineering Tsinghua UniversityKey Laboratory for Advanced Materials Processing TechnologyMinistry of EducationBeijing 100084China

Study on turbine blades is crucial due to their critical role in ensuring the efficient and reliable operation of aircraft ***-based single crystal superalloys are extensively used in the hot manufacturing of turbine blades due to their exceptional high-temperature mechanical *** hot manufacturing of single crystal blades involves directional solidification and heat *** manufacturing of these blades is time-consuming,capital-intensive,and often insufficient to meet industrial *** simulation techniques have gained widespread acceptance in blade manufacturing research due to their low energy consumption,high efficiency,and rapid turnaround *** article introduces the modeling and simulation of hot manufacturing in single crystal *** discussion outlines the prevalent mathematical models employed in numerical simulations related to blade hot *** encapsulates the advancements in research concerning macro to micro-level numerical simulation techniques for directional solidification and heat treatment ***,potential future trajectories for the numerical simulation of single crystal blade hot manufacturing are also discussed.

关键词： single crystal blades Ni-based superalloy directional solidification heat treatment numerical simulation

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Safety analysis of temporary anchorage system for immersed tube in Shenzhen-Zhongshan Link

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Journal of Traffic and Transportation Engineering(English Edition) 2024年第4期11卷 797-813页

作者： Lei yan Jinning yan Guoping xu Shuanhai He Zechen Zhang School of Highway Chang'an UniversityXi'an 710064China Key Laboratory of Transport Industry of Bridge Detection Reinforcement Technology Chang'an UniversityXi'an 710064China CCCC Highway Consultants Co.Ltd. Beijing 100088China

In the construction of the Shenzhen-Zhongshan Link,a temporary anchorage system,distributed uniformly along the pipe wall,has been *** assess the safety and reliability of this system,a combined method utilizing numerical analysis and model experiments was applied to study the safety of the temporary anchorage system and the reliability of the tension ***,an overall model of the caisson segment based on GINA rebound force was established to analyze the stress state of the entire ***,a comprehensive numerical analysis and model experiment verification were conducted for the single tensioning system,revealing its failure mode and safety *** results indicate that the tension rod systems are uniformly stressed at an average of 444 k N during underwater jointing,with a safety factor of *** this point,the maximum von Mises stresses appearing at the front plate corners and the lower edge of the U-groove,with stress values of 181.8 MPa and 172.4 MPa,and safety factors of 1.54 and 1.71,*** the tension rod force reaches 940 k N,the tensioning system reaches its bearing limit,with initial yielding occurring at the front plate *** experiments were conducted to verify the theoretical analysis results,under a test load of 444 k N,the stresses at the front plate corners and the lower edge of the U-groove were 159.6 and 195.9 MPa,*** the test load increased to 940 k N,these stresses reached 390 and 389 MPa,exhibiting good agreement with the numerical *** the uncertainty of loads and materials,a reliability analysis of the tension rods was conducted,yielding a reliability index of 4.34,meeting the secondary safety *** on the comprehensive analysis,it can be concluded that the temporary anchorage system in the caisson segments of the Shenzhen-Zhongshan Link exhibits excellent safety margins.

关键词： Tunnel engineering Immersed tube structure Anchorage system Full-scale model test Load bearing performance Safety assessment

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Experimental and numerical analyses of the effect of fibre content on the close-in blast performance of a UHPFRC beam

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Defence Technology（防务技术） 2024年第1期31卷 242-261页

作者： junbo yan Qiyue Zhang yan Liu Yingliang xu Zhenqing Shi Fan Bai Fenglei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Limited research has been conducted on the influences of fiber content on close-in blasting characteristics for ultrahigh-performance fiber-reinforced concrete(UHPFRC)*** paper aims to address this knowledge gap through experimental and mesoscale numerical *** were conducted on ten UHPFRC beams built with varying steel fiber volumetric fractions subjected to close-in explosive ***,this study considered other parameters,such as the longitudinal reinforcement type and *** the case of UHPFRC beams featuring normal-strength longitudinal reinforcement of diametersΦ12,Φ16,andΦ20,a reduction in maximum displacement by magnitudes of19.6%,19.5%,and 17.4%was observed,respectively,as the volumetric fractions of fiber increased from1.0%to 2.5%.In addition,increasing the longitudinal reinforcement ratio and using high-strength steel longitudinal reinforcement both significantly reduced the deformation characteristics and increase the blasting resistances of UHPFRC ***,the effects on the local crushing and spalling damage were not significant.A mesoscale finite element model,which considers the impacts of fiber parameters on UHPFRC beam behaviors,was also established and well correlated with the test ***,parametric analyses were further conducted to examine the impacts of the steel fiber content and length and the hybrid effects of various types of microfibers and steel fibers on the blasting performance of UHPFRC beams.

关键词： Blast performance Close-in blast Fiber content Mesoscale approach UHPFRC beams

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Prediction of pathological complete response and prognosis in locally advanced rectal cancer

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World Journal of Gastrointestinal Oncology 2024年第6期16卷 2520-2530页

作者： Yi-jun xu Dan Tao Song-Bing Qin Xiao-yan xu Kai-Wen yang Zhong-xu Xing Ju-Ying Zhou yang Jiao Li-Li Wang Department of Radiation Oncology The First Affiliated Hospital of Soochow UniversitySuzhou 215006Jiangsu ProvinceChina Department of Radiation Oncology The Fourth Affiliated Hospital of Soochow UniversitySuzhou 215006Jiangsu ProvinceChina School of Radiation Medicine and Protection Medical College of Soochow UniversitySuzhou 215123Jiangsu ProvinceChina

BACKGROUND Colorectal cancer is currently the third most common malignant tumor and the second leading cause of cancer-related death *** chemoradiotherapy(nCRT)is standard for locally advanced rectal cancer(LARC).Except for pathological examination after resection,it is not known exactly whether LARC patients have achieved pathological complete response(pCR)before *** date,there are no clear clinical indicators that can predict the efficacy of nCRT and patient *** To investigate the indicators that can predict pCR and long-term outcomes following nCRT in patients with *** Clinical data of 128 LARC patients admitted to our hospital between September 2013 and November 2022 were retrospectively *** were categorized into pCR and non-pCR *** analysis(using the χ^(2) test or Fisher’s exact test)and logistic multivariate regression analysis were used to study clinical predictors affecting *** 5-year disease-free survival(DFS)and overall survival(OS)rates were calculated using Kaplan-Meier analysis,and differences in survival curves were assessed with the log-rank *** Univariate analysis showed that pretreatment carcinoembryonic antigen(CEA)level,lymphocyte-monocyte ratio(LMR),time interval between neoadjuvant therapy completion and total mesorectal excision,and tumor size were correlated with *** results showed that CEA≤5 ng/mL(P=0.039),LMR>2.73(P=0.023),and time interval>10 wk(P=0.039)were independent predictors for *** analysis demonstrated that patients in the pCR group had significantly higher 5-year DFS rates(94.7%vs 59.7%,P=0.002)and 5-year OS rates(95.8%vs 80.1%,P=0.019)compared to the non-pCR *** deposits(TDs)were significantly correlated with shorter DFS(P=0.002)and OS(P<0.001).CONCLUSION Pretreatment CEA,LMR,and time interval contribute to predicting nCRT efficacy in LARC *** pCR demonstrates longer DFS and *** correlate with poor pr

关键词： Locally advanced rectal cancer Neoadjuvant chemoradiotherapy Pathological complete response Carcinoembryonic antigen Inflammation-related markers Tumor deposit Prognosis

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Detection of Nonlinear Behavior Induced by Hard Limiting in Voltage Source Converters in Wind Farms Based on Higher-order Spectral Analysis

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 630-645页

作者： Zetian Zheng Shaowei Huang Qiangsheng Bu Chen Shen jun yan State Key Laboratory of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China State Grid Jiangsu Electric Power Co. Ltd.Research InstituteNanjingChina

In recent years, sub-synchronous oscillation accidents caused by wind power integration have received extensive attention. The recorded constant-amplitude waveforms can be induced by either linear or nonlinear oscillation mechanisms. Hence, the nonlinear behavior needs to be distinguished prior to choosing the analysis method. Since the 1960s, the higher-order statistics(HOS) theory has become a powerful tool for the detection of nonlinear behavior(DNB) in production quality control wherein it has mainly been applied to mechanical condition monitoring and fault diagnosis. This study focuses on the hard limiters of the voltage source converter(VSC) control systems in the wind farms and attempts to detect the nonlinear behavior caused by bi-or uni-lateral saturation hard limiting using the HOS analysis. First, the conventional describing function is extended to obtain the detailed frequency domain information on the bi-and uni-lateral saturation hard limiting. Furthermore, the bi-and tri-spectra are introduced as the HOS, which are extended into bi-and tri-coherence spectra to eliminate the effects of the linear parts on the harmonic characteristics of hard limiting in the VSC control system, respectively. The effectiveness of the HOS in the DNB and the classification of the hard-limiting types is proven, and its detailed derivation and estimation procedure is presented. Finally, the quadratic and cubic phase coupling in the signals is illustrated, and the performance of the proposed method is evaluated and discussed.

关键词： Bi-coherence spectrum detection of nonlinear behavior hard limiting higher-order statistics tri-coherence spectrum voltage source converter wind farms.

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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

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Advances in wearable and implantable bioelectronics for precision medicine

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Bio-Design and Manufacturing 2024年第4期7卷 383-387页

作者： Kaichen xu Seung Hwan Ko jun Chen State Key Laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310058China Applied Nano and Thermal Science Lab Department of Mechanical EngineeringSeoul National UniversitySeoul 08826Republic of Korea Department of Bioengineering University of CaliforniaLos AngelesLos AngelesCA 90095-1599USA

The continuous pursuit for a better quality of life promotes continuous advancements in intelligent *** wearable and implantable bioelectronics have emerged as an innovative complement to rigid material-based electronic devices[1-3].Due to their distinct advantages in terms of ductile,ultrathin,and biocompatible features,these elastic and soft bioelectronic devices can be seamlessly mounted onto various real or artificial tissues and organs.

关键词： wear mounted pursuit

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Upwelling current and its relationship to the enrichment of organic matter in the Lower Silurian Longmaxi Formation, northern Chongqing-western Hubei area, southern China

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Journal of Palaeogeography 2024年第4期13卷 993-1015页

作者： jun-jun Shen Jia-Kai yan Peng-Wan Wang Yu-Man Wang Lin Zhou Yu-Bing Ji Min xu Hubei Cooperative Innovation Center of Unconventional Oil and Gas of yangtze University Hydrogeology and Engineering Geology Institute of Hubei Geological Bureau PetroChina Hangzhou Institute of Petroleum Geology PetroChina Research Institute of Petroleum Exploration and Development Exploration and Production Research Institute Zhejiang Oilfield Company Integrated Center of Exploration and Development

Upwelling currents play a crucial role in the enrichment of organic matter, yet the mechanisms driving this process remain incompletely understood due to methodological and data resolution limitations. In this paper, we employ a combination of biostratigraphic classification, qualitative methods, and quantitative methods to systematically analyze the sedimentological and geochemical characteristics of the Lower Silurian Longmaxi Formation in the northern Chongqing-western Hubei area, southern China. The relationship between the upwelling currents and organic matter enrichment in the shale of the Longmaxi Formation is investigated. Results indicate that the upwelling currents in the study area were primarily influenced by the foreland flexure process. From the Rhuddanian(flexure-sedimentation stage) to the Aeronian(flexure-migration stage), the more intense tectonic activity led to gradual opening of the barrier between the South Qinling Ocean and the yangtze Platform, resulting in an increase in the influx of the oceanic current. The upwelling currents significantly contributed to the organic matter production, albeit without substantially affecting the preservation conditions. Throughout the succession of the Longmaxi Formation, the organic matter content decreased gradually from the passive continental margin to the foreland flexural stagnant basin, which was mainly due to deterioration of the preservation conditions as a result of sea level fall and increased terrigenous input. Despite the increase in the upwelling currents, they did not decisively control the organic matter enrichment. Spatially, during the Rhuddanian to Aeronian period, the organic matter content decreased similarly from the passive continental margin to the foreland flexural stagnant basin, influenced by reduced organic matter production caused by weakening of the upwelling currents and the worsening preservation conditions caused by sea-level fall. The terrigenous input had a relatively minor

关键词： Middle–Upper yangtze Ordovician–Silurian transition Black shale Passive continental margin Foreland flexural stagnant basin Sedimentary paleoenvironment

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