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Holder continuous weak solutions of the 2D Boussinesq equation with thermal diffusion

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Science china mathematics 2024年第8期67卷 1777-1806页

作者： Tianwen luo tao tao Liqun Zhang Yau Mathematical Sciences Center Tsinghua UniversityBeijing 100084China School of mathematics Shandong UniversityJinan 250100China institute of mathematics Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing 100049China

We show the existence of Holder continuous periodic weak solutions of the 2D Boussinesq equation with thermal diffusion which satisfy the prescribed kinetic *** precisely,for any smooth e(t):[0,1]→R+andε∈(0,110),there exist v∈C 110−ε([0,1]×T2)andθ∈C 1,120−εt 2 C 2,1 x 10−ε([0,1]×T2),which satisfy(1.1)in the sense of distribution and e(t)=ˆT2|v(t,x)|2 dx,∀t∈[0,1].

关键词： 2D Boussinesq equation with thermal diffusion Holder continuous periodic weak solutions prescribed kinetic energy

Feedback linearization and equivalent-disturbance compensation control strategy for piezoelectric stage

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Nanotechnology and Precision Engineering 2024年第2期7卷 49-59页

作者： tao Huang Yingbin Wang Zhihong luo Huajun Cao Guibao tao Mingxiang Ling State Key Laboratory of Mechanical Transmissions for Advanced Equipment Chongqing UniversityChongqing 400044China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China Hongdu Aviation Industry Group NanchangJiangxi 330000China Robotics and Microsystems Center Soochow UniversitySuzhou 215123China

Piezoelectric stages use piezoelectric actuators and flexure hinges as driving and amplifying mechanisms,*** systems have high positioning accuracy and high-frequency responses,and they are widely used in various precision/ultra-precision positioning ***,the main challenge with these devices is the inherent hysteresis nonlinearity of piezoelectric actuators,which seriously affects the tracking accuracy of a piezoelectric *** by this challenge,in this work,we developed a Hammerstein model to describe the hysteresis nonlinearity of a piezoelectric *** particular,in our proposed scheme,a feedback-linearization algorithm is used to eliminate the static hysteresis *** addition,a composite controller based on equivalent-disturbance compensation was designed to counteract model uncertainties and external *** analysis of the stability of a closed-loop system based on this feedback-linearization algorithm and composite controller was performed,and this was followed by extensive comparative experiments using a piezoelectric stage developed in the *** experimental results confirmed that the feedback-linearization algorithm and the composite controller offer improved linearization and trajectory-tracking performance.

关键词： Piezoelectric stage Hysteresis nonlinearity Feedback linearization Equivalent-disturbance compensation

Increasing operational stability of journal bearing in hydraulic suspension micro-pump by herringbone grooved structure

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Science china(Technological Sciences) 2024年第3期67卷 853-862页

作者： HONG tao XING GuanYing ZUO HuaiYu XUE Song luo XiaoBing State Key Laboratory of Coal Combustion School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The operational stability of radial journal bearings is the bottleneck that limits the reliability of hydraulic suspension micropump. Due to self-excited vibrations, the whirl amplitude of the plain journal bearing(PJB) is large at high rotational speeds,which will accelerate wear failure. It has been proven that employing herringbone grooved journal bearing(HGJB) is an effective method to reduce the whirl amplitude and improve operational stability. However, enhancing the stability of journal bearings in micro-pumps by herringbone grooved structures has rarely been studied, and its effect needs to be verified. We validated the mechanism of the stability improvement with the CFD method and compared the dynamic characteristics of HGJB and PJB by rotor dynamics evaluation and experiment. The experimental results show that under the same conditions the whirl amplitude of the HGJB decreases by 29.61% in the x direction and by 24.09% in the y direction compared with that of the PJB. This study reveals the effect of the herringbone grooved structure on the operational stability of bearings and may provide guidance for the reliability improvement of hydraulic suspension micro-pump.

关键词： journal bearing herringbone groove hydrodynamic effect micro-pump

A combined experimental and DEM investigation of grain interlocking in sheared granular assemblies

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Particuology 2024年第7期90卷 436-451页

作者： Rui Lu Qiang luo Tengfei Wang David P.Connolly tao Xie School of Civil Engineering Southwest Jiaotong UniversityChengdu 610031China Key Laboratory of High-Speed Railway Engineering(Southwest Jiaotong University) Ministry of EducationChengdu 610031China School of Civil Engineering University of LeedsLeeds LS29JTUK Department of Civil Engineering McMaster UniversityHamiltonONCanada

Compacted granular material,integral to geotechnical engineering,undergoes translation,rotation,and interlocking when subject to shear displacements or external *** present study focuses on the interlocking of heterogeneous granular materials,a complex behavior influenced by gradation,compaction,and varying particle geometry,and has consequently received limited attention in existing *** address this research gap,we conducted an analysis on the effect of grain interlocking on the shear resistance of granular assemblies,using a combination of laboratory testing and the discrete element method(DEM).Initially,large-scale direct shear tests were conducted on gravel−sand mixes with varying degrees of compaction and normal *** of the mixes also underwent subsequent shear reversal to explore the differences in grain interlocking between the two shearing processes on the shear *** analyzing the laboratory results,a mesoscopic scale investigation was performed by replicating the test using discrete element *** facilitate this,granular particle geometries were measured using 3D laser scanning based on the physical lab ***,based on these scans,discrete element R-block and ball models were utilized to construct both the coarse and fine particles within the *** vibro-compaction was employed to regulate the degree of *** results indicate that an increase in vertical pressure,coupled with a zero dilatancy angle,results in a rising stress ratio,indicative of grain *** interlocking exhibits a positive correlation with both the coarse content and the degree of compaction,and varies depending on the shear *** interlocking progresses,the shear band,induced by particle movement,expands and is associated with reduced particle rotation near the shear *** study further reveals a consistent positive correlation between interlocking and the principal orientation angle of strong normal c

关键词： Granular material Interlocking Shear resistance Direct shear Discrete element method Vibro-compaction

A universal and ultrafast method for fabricating a library of nanocellulose-supported metal nanoparticles

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Progress in Natural Science:Materials International 2024年第2期34卷 389-395页

作者： Ziyi luo Xiaoyang Wang Baihua Cui Hao luo tao Zhang Jia Ding Yanan Chen Yida Deng Wenbin Hu School of Materials Science and Engineering Tianjin University Department of Chemistry National University of Singapore State Key Laboratory of Marine Resource Utilization in South china Sea School of Materials Science and Engineering Hainan University

Using nanocatalysts to catalyze water electrolysis for hydrogen production is an ideal solution to address the energy *** most well-adopted fabrication methods for nanocatalysts are tube furnace annealing,Hydrothermal method,etc.,hardly satisfying the trade-off among coarsening,dispersity,and particle size due to mutual ***,a universal,ultrafast and facile cellulose nanometer whiskers-high temperature shock（CNWHTS） method was reported for fabricating a library of ultrafine metal nanoparticles with uniform dispersion and narrow size *** metal-anchor functional groups in CNW（i.e.,-OH and-COOH） and the characteristics of the HTS method for ultrafast heating and powerful quenching synergistically contribute to the successful synthesis of metal *** an initial demonstration,the as-prepared Pt nanocatalyst(η10 mA cm-2=51.8 mV) shows more excellent catalytic hydrogen evolution reaction（HER） performance than the Pt catalyst prepared in the tubular furnace(η10 mA cm-2=169.4 mV).This rapid and universal CNW-HTS method can pave the way for nanomanufacturing to produce high-quality metal nanoparticles,thereby expanding applications of energy conversion and electrocatalysis.

关键词： Nanoparticles High-temperature shock Nanocellulose Nanomanufacturing Hydrogen evolution reaction (HER) Electrocatalysis

Surface reconstruction enabled o-PdTe@Pd core-shell electrocatalyst for efficient oxygen reduction reaction

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Chinese Chemical Letters 2024年第8期35卷 314-318页

作者： Min Song Qian Zhang tao Shen Guanyu luo Deli Wang Key Laboratory of Material Chemistry for Energy Conversion and Storage Ministry of EducationSchool of Chemistry and Chemical EngineeringHuazhong University of Science and Technology(HUST)Wuhan 430074China

Palladium-based alloy catalysts have been employed as one of the potential candidates for oxygen reduc-tion reaction(ORR),but the dissolution of transition metal hinders their ***,structure or-dered PdTe intermetallic with Pd shell(o-PdTe@Pd)are synthesized via an electrochemical etching driven surface reconstruction *** surface reconstruction could tune the electronic structure,weaken the adsorption energy of reaction intermediates on o-PdTe@Pd,resulting in enhanced electrocatalytic ac-tivity for *** mass activity of o-PdTe@Pd is about 3.3 and 2.7 times higher than that of Pd/C in acid and alkaline,***,the half-potentials for ORR decay only about 44 mV and 12 mV after 30 k cycles accelerated durability test in acid and alkaline media,*** enhanced dura-bility originates from the resistance of Te atoms dissolve in the ordered PdTe intermetallic core and the core-shell *** assembled in a Zn-air battery,o-PdTe@Pd electrode delivers a higher specific capacity(794 mAh/g)and better cycling stability than Pt/C.

关键词： Surface reconstruction Core-shell structure Intermetallic Oxygen reduction reaction Tellurium

Bio-inspired Design and Inverse Kinematics Solution of an Omnidirectional Humanoid Robotic Arm with Geometric and Load Capacity Constraints

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Journal of Bionic Engineering 2024年第2期21卷 778-802页

作者： Zhichao Zhu Zirong luo Yiming Zhu tao Jiang Minghai Xia Shanjun Chen Boyu Jin College of Intelligence Science and Technology National University of Defense TechnologyChangshaChina

Inspired by the driving muscles of the human arm,a 4-Degree of Freedom(DOF)concentrated driving humanoid robotic arm is proposed based on a spatial double parallel four-bar *** four-bar mechanism design reduces the inertia of the elbow-driving unit and the torque by 76.65%and 57.81%,*** the human pose regulation strategy that the human arm picks up a heavy object by adjusting its posture naturally without complicated control,the robotic arm features an integrated position-level closed-form inverse solution method considering both geometric and load capacity *** method consists of a geometric constraint model incorporating the arm angle(φ)and the Global Configuration(GC)to avoid joint limits and singularities,and a load capacity model to constrain the feasible domain of the arm ***,trajectory tracking simulations and experiments are conducted to validate the feasibility of the proposed inverse solution *** simulated maximum output torque,maximum output power and total energy consumption of the robotic arm are reduced by up to 2.0%,13.3%,and 33.3%,*** experimental results demonstrate that the robotic arm can bear heavy loads in a human-like posture,effectively reducing the maximum output torque and energy consumption of the robotic arm by 1.83%and 5.03%,respectively,while avoiding joints beyond geometric and load capacity *** proposed design provides a high payload–weight ratio and an efficient pose control solution for robotic arms,which can potentially broaden the application spectrum of humanoid robots.

关键词： Humanoid robotic arm Bio-inspired design Inverse kinematics solution Load capacity constraint Geometric constraint

Trend of Storm Surge Induced by Typical Landfall Super Typhoons During 1975–2021 in the Eastern china Sea

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Journal of Ocean University of china 2024年第2期23卷 277-286页

作者： luo Feng WANG Yi tao Aifeng SHI Jian WANG Yongzhi ZHANG Chi College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing 210098China Nantong Ocean and Coastal Engineering Research institute Hohai UniversityNantong 226000China Key Laboratory of Ministry of Education for Coastal Disaster and Protection Hohai UniversityNanjing 210098China College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China The First institute of Oceanography MNRQingdao 266061China

Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental *** a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical *** TY activity was then analyzed using historical *** showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern china Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in ***,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical *** by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration *** addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster *** by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North china faced potential growth in high storm surge risks.

关键词： storm surge super typhoons tropical cyclones eastern china Sea poleward migration

Impact of next-generation sequencing on antimicrobial treatment in immunocompromised adults with suspected infections

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World Journal of Emergency Medicine 2024年第2期15卷 105-110页

作者： Jia Li Jiazhen luo tao Hu Ling Cheng Weiwei Shang Li Yan Department of Intensive Care Unit Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Department of Emergency Medicine Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China Tongji Medical College Huazhong University of Science and TechnologyWuhan 430030China Department of Geriatrics Tongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China

BACKGROUND:Prompt pathogen identification can have a substantial impact on the optimization of antimicrobial *** objective of the study was to assess the diagnostic value of next-generation sequencing(NGS)for identifying pathogen and its clinical impact on antimicrobial intervention in immunocompromised patients with suspected ***:This was a retrospective *** January and August 2020,47 adult immunocompromised patients underwent NGS testing under the following clinical conditions:1)prolonged fever and negative conventional cultures;2)new-onset fever despite empiric antimicrobial treatment;and 3)afebrile with suspected infections on *** data,including conventional microbial test results and antimicrobial treatment before and after NGS,were *** were analyzed according to documented changes in antimicrobial treatment(escalated,no change,or deescalated)after the NGS ***:The median time from hospitalization to NGS sampling was 19 *** relevant pathogens were detected via NGS in 61.7% of patients(29/47),more than half of whom suffered from fungemia(n=17),resulting in an antimicrobial escalation in 53.2% of patients(25/47)and antimicrobial de-escalation in 0.2% of patients(1/47).Antimicrobial changes were mostly due to the identification of fastidious organisms such as Legionella,Pneumocystis jirovecii,and *** the remaining three cases,NGS detected clinically relevant pathogens also detected by conventional cultures a few days *** antimicrobial treatment was subsequently adjusted according to the susceptibility test ***,NGS changed antimicrobial management in 55.3%(26/47)of patients,and conventional culture detected clinically relevant pathogens in 14.9% of the patients(7/47).CONCLUSION:With its rapid identification and high sensitivity,NGS could be a promising tool for identifying relevant pathogens and enabling rapid appropriate treatment in immunocompromised patients w

关键词： Immunocompromised patients Next-generation sequencing Antimicrobial management