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Pressure effects on metal/covalent-organic frameworks:structural and optical properties

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Science China Chemistry 2024年第9期67卷 2890-2903页

作者： yixuan wang Yunfeng Yang Xinyi Yang Bo Zou Synergetic Extreme Condition High-Pressure Science Center State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin UniversityChangchun 130012China

Metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)with highly ordered porous structure,tunable bandgap,large specific surface area and structural diversity,provide an appealing platform for the development of stimulus response,sensing,imaging and *** various tuning methods,pressure engineering using the diamond anvil cell is a highly powerful in-situ technique,which can efficiently modulate the structural and optical properties of MOFs/*** is beyond the realization of traditional chemical *** review outlines the research progress in the experimentoriented discovery of new phases or unique properties under high pressure,including phase transition,abnormal compression,photoluminescence(PL)discoloration and ***,the improvement of PL quantum yield in MOFs could be achieved by pressure-treated engineering and hydrogen-bonding cooperativity *** also propose and establish the relationship between structure and optical properties under high ***,the challenge and outlook of the current fields are *** hope that this review will supply guidance for comprehending the development of high-pressure MOF/COF-related research fields,and offer novel strategies for designing more high-performance MOF/COF materials to ultimately expand their applications.

关键词： metal/covalent-organic frameworks pressure engineering phase transition abnormal compressive behaviors piezochromic behaviors emission enhancement

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Model Parameters Identification and Backstepping Control of Lower Limb Exoskeleton Based on Enhanced Whale Algorithm

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 100-114页

作者： Yan Shi Jiange Kou Zhenlei Chen yixuan wang Qing Guo School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China School of Aeronautics and Astronautics University of Electronic Science and Technology of ChinaChengdu 611731China

Exoskeletons generally require accurate dynamic models to design the model-based controller conveniently under the human-robot interaction ***,due to unknown model parameters such as the mass,moment of inertia and mechanical size,the dynamic model of exoskeletons is difficult to ***,an enhanced whale optimization algorithm(EWOA)is proposed to identify the exoskeleton model ***,the periodic excitation trajectories are designed by finite Fourier series to input the desired position demand of exoskeletons with mechanical physical *** a backstepping controller based on the identified model is adopted to improve the human-robot wearable comfortable performance under cooperative ***,the proposed Model parameters identification and control are verified by a two-DOF exoskeletons *** knee joint motion achieves a steady-state response after 0.5 ***,the position error of hip joint response is less than 0.03 rad after 0.9 *** addition,the steady-state human-robot interaction torque of the two joints is constrained within 15 N·*** research proposes a whale optimization algorithm to optimize the excitation trajectory and identify model ***,an enhanced mutation strategy is adopted to avoid whale evolution’s unsatisfactory local optimal value.

关键词： Parameter identification Enhanced whale optimization algorithm(EWOA) Backstepping Human-robot interaction Lower limb exoskeleton

Exponentially Convergent Multiscale Finite Element Method

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Communications on Applied Mathematics and Computation 2024年第2期6卷 862-878页

作者： Yifan Chen Thomas Y.Hou yixuan wang Applied and Computational Mathematics CaltechPasadena 91106USA

We provide a concise review of the exponentially convergent multiscale finite element method(ExpMsFEM)for efficient model reduction of PDEs in heterogeneous media without scale separation and in high-frequency wave *** ExpMsFEM is built on the non-overlapped domain decomposition in the classical MsFEM while enriching the approximation space systematically to achieve a nearly exponential convergence rate regarding the number of basis *** most generalizations of the MsFEM in the literature,the ExpMsFEM does not rely on any partition of unity *** general,it is necessary to use function representations dependent on the right-hand side to break the algebraic Kolmogorov n-width barrier to achieve exponential ***,there are online and offline parts in the function representation provided by the *** online part depends on the right-hand side locally and can be computed in parallel *** offline part contains basis functions that are used in the Galerkin method to assemble the stiffness matrix;they are all independent of the right-hand side,so the stiffness matrix can be used repeatedly in multi-query scenarios.

关键词： Multiscale method Exponential convergence Helmholtz's equation Domain decomposition Nonlinear model reduction

Flexible assistance strategy of lower limb rehabilitation exoskeleton based on admittance model

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Science China(Technological Sciences) 2024年第3期67卷 823-834页

作者： KOU JianGe wang yixuan CHEN ZhenLei SHI Yan GUO Qing XU Meng School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China School of Aeronautics and Astronautics University of Electronic Science and Technology of ChinaChengdu 611731China Department of Musculoskeletal Tumor Senior Department of Orthopedicsthe Fourth Medical Centerof PLA GeneralHospitalBeijing 100853China

Exercise training based on exoskeleton is an effective rehabilitation method for stroke patients. However, some rehabilitation exoskeletons still have poor wearable performance and obvious human-robot impedance during training, which easily cause secondary injuries to the patients. In this study, a variable admittance control strategy is proposed to improve the operator's wearable comfort, which can adapt to different operators by regulating admittance parameters. The admittance controller has two feedback loops: the position inner-loop and the admittance outer-loop. Meanwhile, the exoskeleton Lagrange model is constructed with unknown friction disturbance. By using Lyapunov technique and backstepping with state observer, the joint position error of exoskeleton is convergence into a zero neighborhood. The effectiveness of the proposed admittance controller is verified by both simulation and experiment. The tracking error of hip and knee joint is less than 4 degrees while the human-robot interaction torque is constrained in a tolerable range of the operator.

关键词： human-robot interaction exoskeleton backstepping admittance control

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New technology for pipeline defect detection

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Science China(Technological Sciences) 2024年第4期67卷 1294-1296页

作者： NIU YanXia SUN LongXiang wang yixuan SHEN GuoLang SHI Yan Engineering Training Center Beihang UniversityBeijing 102206China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China School of Mechanical and Electronic Engineering Jingdezhen Ceramic UniversityJingdezhen 333403China

Rupture and leakage of urban sewer pipes will seriously affect the daily life of urban *** detection is one of the most important segments in the assessment of pipeline health *** the continuous extension of pipeline ... 详细信息

关键词： corrosion defect pipeline

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Wettability-driven synergistic resistance of scale and oil on robust superamphiphobic coating

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Chinese Chemical Letters 2024年第7期35卷 433-438页

作者： yixuan wang Jiexin Li Zhihao Shang Chengcheng Feng Jianmin Gu Maosheng Ye Ran Zhao Danna Liu Jingxin Meng Shutao wang CAS Key Laboratory of Bio-inspired Materials and Interfacial Science Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences(UCAS) Beijing 100049China State Key Laboratory of Metastable Materials Science and Technology(MMST) Yanshan UniversityQinhuangdao 066004China

Disgusting deposits(e.g.,scale and crude oil)in daily life and industrial production are always serious problems,posing great threats to the safety and economic ***,most of developed coatings can only conquer one part of these deposits such as superhydrophobic coatings possess antiscaling capacity but would adhere crude *** integrate scale resistance with oil repellence,we herein report a robust superamphiphobic(SAB)coating simultaneously reducing pollution of scale and oil for extended period of time(two weeks with over 98%reduction).Compared with single role of superhydrophobic and amphiphilic surfaces,the SAB coating can not only inhibit interfacial nucleation of scale but also reduce the adhesion of formed scale and polluted *** durability of the SAB coating is evaluated via mechanical tests(sandpaper abrasion,tape stripping and sand falling)and chemical corrosion(corrosive liquid immersing),revealed by sustainable high contact angles and low contact angle hysteresis of water and *** universality of this strategy can be further confirmed by adding different particles like kaolin,Al_(2)O_(3),and SiO_(2),resisting multiple types of scale(i.e.,CaSO_(4),BaSO_(4)and MgCO_(3))and oil(i.e.,glycerol,glycol,and mineral oil).Therefore,this study provides an ideal avenue for resisting scale and oil,which may be used for conquering the complexity of application environments(e.g.,oil production and transportation).

关键词： Superamphiphobic Durability Wettability Anti-scaling Oil repellence

Chipless textile electronics:Guokai Cuihuman body-coupled fiber for wireless energy harvesting and signal transmission

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Science China Materials 2024年

作者： yixuan wang Zuqing Yuan Guozhen Shen School of Integrated Circuits and Electronics Beijing Institute of Technology

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Simulation Method and Feature Analysis of Shutdown Pressure Evolution During Multi-Cluster Fracturing Stimulation

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Energy Engineering 2024年第1期121卷 111-123页

作者： Huaiyin He Longqing Zou Yanchao Li yixuan wang Junxiang Li Huan Wen Bei Chang Lijun Liu Shale Gas Exploration and Development Department CNPC Chuanqing Drilling Engineering Co.Ltd.Chengdu610051China College of Energy Chengdu University of TechnologyChengdu610059China

Multistage multi-cluster hydraulic fracturing has enabled the economic exploitation of shale reservoirs,but the interpretation of hydraulic fracture parameters is *** pressure signals after pump shutdown are influenced by hydraulic fractures,which can reflect the geometric features of hydraulic *** shutdown pressure can be used to interpret the hydraulic fracture parameters in a real-time and cost-effective *** this paper,a mathematical model for shutdown pressure evolution is developed considering the effects of wellbore friction,perforation friction and fluid loss in *** efficient numerical simulation method is established by using the method of *** on this method,the impacts of fracture half-length,fracture height,opened cluster and perforation number,and filtration coefficient on the evolution of shutdown pressure are *** results indicate that a larger fracture half-length may hasten the decay of shutdown pressure,while a larger fracture height can slow down the decay of shutdown pressure.A smaller number of opened clusters and perforations can significantly increase the perforation friction and decrease the overall level of shutdown pressure.A larger filtration coefficient may accelerate the fluid filtration in the fracture and hasten the drop of the shutdown *** simulation method of shutdown pressure,as well as the analysis results,has important implications for the interpretation of hydraulic fracture parameters.

关键词： Multistage multi-cluster hydraulic fracturing pump shutdown pressure feature analysis numerical simulation

等离子体渗氮气压对合金钢渗氮层微观结构和性能的影响

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表面技术 2024年第7期53卷 200-207页

作者：王怡萱安徽工业大学材料科学与工程学院安徽马鞍山243002

目的选择M50NiL钢(高合金钢)和AISI 4140钢(低合金钢)2种合金钢,研究渗氮气压对合金钢等离子体渗氮层组织结构、渗层厚度、硬度、韧性和摩擦磨损性能的影响规律。方法根据离子渗氮GB/T 30883—2017,在0~500 Pa渗氮气压范围内选择170、25... 详细信息

目的选择M50NiL钢(高合金钢)和AISI 4140钢(低合金钢)2种合金钢,研究渗氮气压对合金钢等离子体渗氮层组织结构、渗层厚度、硬度、韧性和摩擦磨损性能的影响规律。方法根据离子渗氮GB/T 30883—2017,在0~500 Pa渗氮气压范围内选择170、250、350 Pa 3个渗氮气压进行等离子体渗氮,研究渗层微观结构和性能。结果对于M50NiL和AISI 4140两种合金钢,350 Pa时渗层厚度均最大,170 Pa次之,250 Pa厚度最小。M50NiL钢在350 Pa渗氮和AISI 4140钢在170 Pa渗氮时,表面层具有最优的强韧性。摩擦磨损性能显示,170 Pa和350 Pa气压渗氮的摩擦磨损性能明显优于250 Pa气压渗氮,其中磨损率规律与渗氮层的韧性值测试结果吻合。结论气压影响了氮离子的能量和分布,从而影响了渗层厚度,钢中的合金元素含量和气压共同影响表面强韧化效果,并且表面强韧化效果直接影响渗氮层的摩擦磨损性能。

关键词：气压等离子体渗氮硬度摩擦磨损合金钢