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Reorientation and obstacle avoidance control of free-floating modular robots using sinusoidal oscillator

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Chinese Journal of Aeronautics 2024年第6期37卷 262-275页

作者： Zhiyuan YANG Mingzhu LAI Jian QI Ning zhao Xin SUI Jie zhao Yanhe ZHU State Key Laboratory of Robotics and System Harbin Institute of TechnologyHarbin 150001China School of Mathematics and Statistics Hainan Normal UniversityHaikou 571158China

This paper presents that a serpentine curve-based controller can solve locomotion control problems for articulated space robots with extensive flight phases,such as obstacle avoidance during free floating or attitude adjustment before *** proposed algorithm achieves articulated robots to use closed paths in the joint space to accomplish the above *** snakes,which can shuttle through gaps and adjust their landing posture by swinging their body during gliding in jungle environments,inspired the design of two *** first maneuver generates a rotation of the system by varying the moment of inertia between the joints of the robot,with the magnitude of the net rotation depending on the controller *** maneuver can be repeated to allow the robot to reach arbitrary *** second maneuver involves periodic undulations,allowing the robot to avoid collisions when the trajectory of the global Center of Mass(CM)passes through the *** maneuvers are based on the improved serpenoid curve,which can adapt to redundant systems consisting of different numbers of ***,the simulation illustrates that combining the two maneuvers can help a free-floating chain-type robot traverse complex *** proposed algorithm can be used with similar articulated robot models.

关键词： Collision avoidance Modularrobots Reorientation Free-floating space robots Nonholonomic systems Biologically inspired controllers Serpenoid curve

An oscillation-free Hermite WENO scheme for hyperbolic conservation laws

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Science China Mathematics 2024年第2期67卷 431-454页

作者： Zhuang zhao Jianxian Qiu School of Mathematical Sciences and Institute of Natural Sciences Shanghai Jiao Tong UniversityShanghai 200240China School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific Computing Xiamen UniversityXiamen 361005China

In this paper, the sixth-order oscillation-free Hermite weighted essentially non-oscillatory (OFHWENO) scheme is proposed for hyperbolic conservation laws on structured meshes, where the zeroth- andfirst-order moments are the variables for the governing equations. The main difference from other HWENOschemes existing in the literature is that we add high-order numerical damping terms in the first-order momentequations to control spurious oscillations for the OF-HWENO scheme. The OF-HWENO scheme not only canachieve the designed optimal numerical order, but also can be easily implemented as we use only one set ofstencils in the reconstruction procedure and the same reconstructed polynomials are applied for the zeroth- andfirst-order moment equations. In order to obtain the adaptive order resolution when facing discontinuities, atransition polynomial is added in the reconstruction, where the associated linear weights can also be any positivenumbers as long as their summation equals one. In addition, the OF-HWENO scheme still keeps compactnessas only immediate neighbor values are needed in the space discretization. Some benchmark numerical tests areperformed to illustrate the high-order accuracy, high resolution and robustness of the proposed scheme.

关键词： Hermite WENO scheme hyperbolic conservation laws oscillation-free adaptive order discontinuous Galerkin method

UniBind:a novel artificial intelligence-based prediction model for SARS-CoV-2 infectivity and variant evolution

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Signal Transduction and Targeted Therapy 2024年第1期9卷 14-15页

作者： Qihong Yan Jincun zhao State Key Laboratory of Respiratory Disease National Clinical Research Center for Respiratory DiseaseGuangzhou Institute of Respiratory Healththe First Affiliated Hospital of Guangzhou Medical UniversityGuangzhouChina

In a recent study published in Nature Medicine,Wang et *** an excellent framework called UniBind based on artificial intelligence(AI),which enables accurately predicting infectivity of SARS-CoV-2 variants and evolutionary trends of future viral variants.1 This computational method holds the possibility to not only serve as a valuable early-warning tool for monitoring potential pathogenic SARS-CoV-2 variants but also facilitate fundamental research on protein-protein interactions(PPIs).

关键词： artificial Bind prediction

Enhanced stability of nitrogen-doped carbon-supported palladium catalyst for oxidative carbonylation of phenol

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Chinese Journal of Chemical Engineering 2024年第1期65卷 19-28页

作者： Xiaojing Liu Ruohan zhao Hao zhao Zhimiao Wang Fang Li Wei Xue Yanji Wang Hebei Provincial Key Laboratory of Green Chemical Technology and High Efficient Energy Saving School of Chemical Engineering and TechnologyHebei University of TechnologyTianjin 300130China Tianjin Key Laboratory of Chemical Process Safety Tianjin 300130China Hebei Industrial Technology Research Institute of Green Chemical Industry Huanghua 061100China

Enhancing the stability of supported noble metal catalysts emerges is a major challenge in both science and ***,a heterogeneous Pd catalyst(Pd/NCF)was prepared by supporting Pd ultrafine metal nanoparticles(NPs)on nitrogen-doped carbon;synthesized by using F127 as a stabilizer,as well as chitosan as a carbon and nitrogen *** Pd/NCF catalyst was efficient and recyclable for oxidative carbonylation of phenol to diphenyl carbonate,exhibiting higher stability than Pd/NC prepared without F127 *** hydrogen bond between chitosan(CTS)and F127 was enhanced by F127,which anchored the N in the free amino group,increasing the N content of the carbon material and ensuring that the support could provide sufficient N sites for the deposition of Pd *** process helped to improve metal *** increased metal-support interaction,which limits the leaching and coarsening of Pd NPs,improves the stability of the Pd/NCF ***,density functional theory calculations indicated that pyridine N stabilized the Pd^(2+)species,significantly inhibiting the loss of Pd^(2+)in Pd/NCF during the reaction *** work provides a promising avenue towards enhancing the stability of nitrogen-doped carbon-supported metal catalysts.

关键词： Supported Pd catalyst N-doped carbon Amphiphilic triblock copolymer Pyridinic nitrogen Stability

Leakage and diffusion characteristics of underground hydrogen pipeline

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Petroleum 2024年第2期10卷 319-325页

作者： Wenkang Zhang Guanghui zhao School of Mechatronic Engineering Southwest Petroleum University

Soil corrosion and hydrogen embrittlement are the main factors of hydrogen pipeline failure. The gas escapes, diffuses and accumulates in the soil and enters the atmosphere when leak occurs. The mechanism of gas diffusion in buried pipelines is very complicated. Mastering the evolution law of hydrogen leakage diffusion is conducive to quickly locating the leakage point and reducing the loss. The leakage model of the underground hydrogen pipeline is established in this paper. The effect of leakage hole, soil type, pipeline pressure, pipeline diameter on hydrogen leakage diffusion were investigated. The results show that when the hydrogen pipeline leaks, the hydrogen concentration increases with the increase of leakage time, showing a symmetrical distribution trend. With the pipeline pressure increase, hydrogen leakage speed is accelerated, and longitudinal diffusion gradually becomes the dominant direction. As the leakage diameter increases, hydrogen leakage per unit of time increases sharply. Hydrogen diffuses more easily in sandy soil, and its diffusion speed, concentration, and range are higher than that in clay soil. The research content provides a reference and basis for the detection and evaluation of buried hydrogen pipeline leakage.

关键词： Buried pipeline Hydrogen leakage Diffusion characteristics Numerical simulation

Passivity-Based Stabilization for Switched Stochastic Nonlinear Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1307-1309页

作者： Yaowei Sun Jun zhao School of Automation Zhengzhou University of AeronauticsZhengzhou 450046 Henan Key Laboratory of General Aviation Technology Zhengzhou University of AeronauticsZhengzhou 450046China College of Information Science and Engineering Northeastern UniversityShenyang 110819China

Dear Editor,This letter addresses the passivity-based mean square exponential stabilization problem for switched stochastic nonlinear systems.A concept of generalized small-time norm-observability is presented and an appropriate test condition is also *** pre-given passivity rate and average dwell time,a set of feedback controllers is designed by use of the passivity property.

关键词： property letter stabilization

A sub-grid scale model for Burgers turbulence based on the artificial neural network method

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Theoretical & Applied Mechanics Letters 2024年第3期14卷 162-165页

作者： Xin zhao Kaiyi Yin Department of Mechanics Beijing Institute of TechnologyBeijing 100081China

The present study proposes a sub-grid scale model for the one-dimensional Burgers turbulence based on the neuralnetwork and deep learning *** filtered data of the direct numerical simulation is used to establish thetraining data set,the validation data set,and the test data *** artificial neural network(ANN)methodand Back Propagation method are employed to train parameters in the *** developed ANN is applied toconstruct the sub-grid scale model for the large eddy simulation of the Burgers turbulence in the *** proposed model well predicts the time correlation and the space correlation of the Burgers turbulence.

关键词： Artificial neural network Back propagation method Burgers turbulence Large eddy simulation Sub-grid scale model

A Lightweight, Searchable, and Controllable EMR Sharing Scheme

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Computers, Materials & Continua 2024年第4期79卷 1521-1538页

作者： Xiaohui Yang Peiyin zhao School of Cyber Security and Computer Hebei UniversityBaoding071000China

Electronic medical records (EMR) facilitate the sharing of medical data, but existing sharing schemes suffer fromprivacy leakage and inefficiency. This article proposes a lightweight, searchable, and controllable EMR sharingscheme, which employs a large attribute domain and a linear secret sharing structure (LSSS), the computationaloverhead of encryption and decryption reaches a lightweight constant level, and supports keyword search andpolicy hiding, which improves the high efficiency of medical data sharing. The dynamic accumulator technologyis utilized to enable data owners to flexibly authorize or revoke the access rights of data visitors to the datato achieve controllability of the data. Meanwhile, the data is re-encrypted by Intel Software Guard Extensions(SGX) technology to realize resistance to offline dictionary guessing attacks. In addition, blockchain technology isutilized to achieve credible accountability for abnormal behaviors in the sharing process. The experiments reflectthe obvious advantages of the scheme in terms of encryption and decryption computation overhead and storageoverhead, and theoretically prove the security and controllability in the sharing process, providing a feasible solutionfor the safe and efficient sharing of EMR.

关键词： Lightweight keyword search large attribute domain controllability blockchain

渐开线齿形零件精冲尺寸精度分析及工艺参数优化

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锻压技术 2022年第8期47卷 83-87,117页

作者：李华建赵彦启肖振沿刘金菊中机精冲科技(福建)有限公司福建三明365500

采用Deform-3D软件对某汽车变速箱零件渐开线花键孔的精冲成形进行模拟,分析花键孔精冲有限元模型的结构特点,以点的位移量作为花键孔精冲模拟尺寸精度的评价标准。采用全面试验设计法研究凸凹模间隙、凸模圆角半径和压边力3个工艺参数... 详细信息

采用Deform-3D软件对某汽车变速箱零件渐开线花键孔的精冲成形进行模拟,分析花键孔精冲有限元模型的结构特点,以点的位移量作为花键孔精冲模拟尺寸精度的评价标准。采用全面试验设计法研究凸凹模间隙、凸模圆角半径和压边力3个工艺参数对精冲成形结果的影响,获得最优工艺参数组合为:凸凹模间隙为0.04 mm、凸模圆角半径为0.4 mm和压边力为724 kN,利用极差分析方法得出各因素对花键孔精冲尺寸精度的影响程度大小依次为凸凹模间隙>凸模圆角半径>压边力。采用插值法对最优工艺参数组合模拟试验中的凸模进行应力分析,并预测凸模的使用寿命为4825次,符合设计预期。最后,采用优化后的工艺参数组合进行了实际花键孔精冲试验,花键孔的成形尺寸精度得到了明显提升。

关键词：渐开线花键孔极差分析插值法凸模使用寿命尺寸精度