期刊文献+
共找到21,717篇文章
< 1 2 250 >
每页显示 20 50 100
Early intelligent active assistance in walking for hemiplegic patients under suspension protection: a randomized controlled trial
1
作者 Ma Shanxin Zheng Jianling +5 位作者 Cheng Jian Lin Xi Li Qiuyuan Wang Li Zeng Yangkang Song Luping 《中国组织工程研究》 北大核心 2026年第12期3075-3082,共8页
BACKGROUND:Hemiplegia,a prevalent stroke-related condition,is often studied for motor dysfunction;however,spasticity remains under-researched.Abnormal muscle tone significantly hinders hemiplegic patients’walking rec... BACKGROUND:Hemiplegia,a prevalent stroke-related condition,is often studied for motor dysfunction;however,spasticity remains under-researched.Abnormal muscle tone significantly hinders hemiplegic patients’walking recovery.OBJECTIVE:To determine whether early suspension-protected training with a personal assistant machine for stroke patients enhances walking ability and prevents muscle spasms.METHODS:Thirty-two early-stage stroke patients from Shenzhen University General Hospital and the China Rehabilitation Research Center were randomly assigned to the experimental group(n=16)and the control group(n=16).Both groups underwent 4 weeks of gait training under the suspension protection system for 30 minutes daily,5 days a week.The experimental group used the personal assistant machine during training.Three-dimensional gait analysis(using the Cortex motion capture system),Brunnstrom staging,Fugl-Meyer Assessment for lower limb motor function,Fugl-Meyer balance function,and the modified Ashworth Scale were evaluated within 1 week before the intervention and after 4 weeks of intervention.RESULTS AND CONCLUSION:After the 4-week intervention,all outcome measures showed significant changes in each group.The experimental group had a small but significant increase in the modified Ashworth Scale score(P<0.05,d=|0.15|),while the control group had a large significant increase(P<0.05,d=|1.48|).The experimental group demonstrated greater improvements in walking speed(16.5 to 38.44 cm/s,P<0.05,d=|4.01|),step frequency(46.44 to 64.94 steps/min,P<0.05,d=|2.32|),stride length(15.50 to 29.81 cm,P<0.05,d=|3.44|),and peak hip and knee flexion(d=|1.82|to|2.17|).After treatment,the experimental group showed significantly greater improvements than the control group in walking speed(38.44 vs.26.63 cm/s,P<0.05,d=|2.75|),stride length,peak hip and knee flexion(d=|1.31|to|1.45|),step frequency(64.94 vs.59.38 steps/min,P<0.05,d=|0.85|),and a reduced support phase(bilateral:24.31%vs.28.38%,P<0.05,d=|0.88|;non-paretic:66.19%vs.70.13%,P<0.05,d=|0.94|).For early hemiplegia,personal assistant machine-assisted gait training under the suspension protection system helps establish a correct gait pattern,prevents muscle spasms,and improves motor function. 展开更多
关键词 hemiplegia stroke suspension protection system personal assistant machine intelligent walking aid early rehabilitation active training walking function NEUROPLASTICITY gait analysis motor function recovery rehabilitation training balance ability
暂未订购
Pressure in active matter
2
作者 Guo Yu Ruiyao Li +5 位作者 Fukang Li Jiayu Zhang Xiyue Li Zequ Chen Joscha Mecke Yongxiang Gao 《Chinese Physics B》 2025年第9期330-342,共13页
In the last decade,the study of pressure in active matter has attracted growing attention due to its fundamental relevance to nonequilibrium statistical physics.Active matter systems are composed of particles that con... In the last decade,the study of pressure in active matter has attracted growing attention due to its fundamental relevance to nonequilibrium statistical physics.Active matter systems are composed of particles that consume energy to sustain persistent motion,which are inherently far from equilibrium.These particles can exhibit complex behaviors,including motility-induced phase separation,clustering,and anomalous stress distributions,motivating the introduction of active swim stress and swim pressure.Unlike in passive fluids,pressure in active systems emerges from momentum flux originating from swim force rather than equilibrium conservative interactions,offering a distinct perspective for understanding their mechanical response.Simple models of active Brownian particles(ABPs)have been employed in theoretical and simulation studies across both dilute and dense regimes,revealing that pressure is a state function and exhibits a nontrivial dependence on density.Together with nonequilibrium statistical concepts such as effective temperature and effective adhesion,pressure offers important insight for understanding behaviors in active matter such as sedimentation equilibrium and motility induced phase separation.Extensions of ABP models beyond their simplest form have underscored the fragility of the pressure-based equation of state,which can break down under factors such as density-dependent velocity,torque,complex boundary geometries and interactions.Building on these developments,this review provides a comprehensive survey of theoretical and experimental advances,with particular emphasis on the microscopic origins of active pressure and the mechanisms underlying the breakdown of the equation of state. 展开更多
关键词 active matter active pressure equation of state active Brownian particles
原文传递
Reactive Power Optimization Model of Active Distribution Network with New Energy and Electric Vehicles 被引量:1
3
作者 Chenxu Wang Jing Bian Rui Yuan 《Energy Engineering》 2025年第3期985-1003,共19页
Considering the uncertainty of grid connection of electric vehicle charging stations and the uncertainty of new energy and residential electricity load,a spatio-temporal decoupling strategy of dynamic reactive power o... Considering the uncertainty of grid connection of electric vehicle charging stations and the uncertainty of new energy and residential electricity load,a spatio-temporal decoupling strategy of dynamic reactive power optimization based on clustering-local relaxation-correction is proposed.Firstly,the k-medoids clustering algorithm is used to divide the reduced power scene into periods.Then,the discrete variables and continuous variables are optimized in the same period of time.Finally,the number of input groups of parallel capacitor banks(CB)in multiple periods is fixed,and then the secondary static reactive power optimization correction is carried out by using the continuous reactive power output device based on the static reactive power compensation device(SVC),the new energy grid-connected inverter,and the electric vehicle charging station.According to the characteristics of the model,a hybrid optimization algorithm with a cross-feedback mechanism is used to solve different types of variables,and an improved artificial hummingbird algorithm based on tent chaotic mapping and adaptive mutation is proposed to improve the solution efficiency.The simulation results show that the proposed decoupling strategy can obtain satisfactory optimization resultswhile strictly guaranteeing the dynamic constraints of discrete variables,and the hybrid algorithm can effectively solve the mixed integer nonlinear optimization problem. 展开更多
关键词 active distribution network new energy electric vehicles dynamic reactive power optimization kmedoids clustering hybrid optimization algorithm
在线阅读 下载PDF
Research Advances in the Control of Spider Mites Using Bioactive Substances of Biological Origin
4
作者 Tongshu DAI Kaicheng LIU Yanjie LUO 《Asian Agricultural Research》 2025年第11期51-53,共3页
Spider mites are significant pests in agricultural production.The increasing resistance of spider mites,along with environmental pollution and ecological imbalance caused by their control,is primarily attributed to th... Spider mites are significant pests in agricultural production.The increasing resistance of spider mites,along with environmental pollution and ecological imbalance caused by their control,is primarily attributed to the long-term use of chemical acaricides in agriculture.In contrast,bioactive substances of biological origin offer advantages such as wide availability,environmental friendliness,and low tendency to induce resistance,making them a research hotspot for spider mite control.This review summarizes recent advances in the use of plant-derived active compounds(exemplified by extracts from Veratrum rhizomes),RNA interference(RNAi)technology,and microorganism-derived active substances for controlling spider mites.These bioactive agents exert acaricidal effects by disrupting the nervous system,interfering with metabolic processes,or silencing key genes in mites,demonstrating favorable efficacy and considerable potential for development.However,challenges remain,including poor environmental stability,slow action,high production costs,and insufficient understanding of their effects on non-target organisms.Therefore,future research should focus on the screening and development of novel bioactive substances of biological origin,elucidation of their mechanisms of action,optimization of formulation technologies,and assessment of their ecological safety.These efforts will provide valuable insights for promoting the advancement of bioactive substances and supporting sustainable agricultural development. 展开更多
关键词 Bioactive substances of BIOLOGICAL ORIGIN Spider MITE CONTROL RNA interference Plant-derived active substances Microorganism-derived active substances
在线阅读 下载PDF
Applicability of electrical resistivity surveys for tracing and characterizing active faults:a case study in the Northern Gongju Fault Zone,Korea
5
作者 Samgyu Park Youngbeom Cheon +1 位作者 Taehyung Kim Jin-Hyuck Choi 《Episodes》 2025年第3期295-305,共11页
In slowly deforming intraplate regions,identifying active faults is challenging due to their low slip rates or concealment by recent sedimentation and anthropogenic activity,requiring significant time and resources.We... In slowly deforming intraplate regions,identifying active faults is challenging due to their low slip rates or concealment by recent sedimentation and anthropogenic activity,requiring significant time and resources.We focus on the structural features and spatial extent of a buried active reverse fault,central South Korea.Our approach integrates the structural and paleoseismic records from the fault exposure with 2D and 3D electrical resistivity surveys.In the road construction area,electrical resistivity differentiates the fault’s hanging wall from the footwall in granitic bedrock. 展开更多
关键词 buried active reverse fault paleoseismic records structural features active faults resistivity diff intraplate regions electrical resistivity surveys structural paleoseismic records
在线阅读 下载PDF
A hydrogen-centric perspective on electrocatalytic nitrate reduction:Managing the active hydrogen lifecycle from generation to utilization
6
作者 Zhihao Wang Xu Zhang +1 位作者 Zhiyu Ren Zhimin Chen 《Journal of Energy Chemistry》 2025年第10期210-230,共21页
Electrocatalytic nitrate reduction reaction(NitRR)utilizing water as a hydrogen source under ambient conditions represents a highly promising avenue for sustainable ammonia synthesis and environmental remediation.Howe... Electrocatalytic nitrate reduction reaction(NitRR)utilizing water as a hydrogen source under ambient conditions represents a highly promising avenue for sustainable ammonia synthesis and environmental remediation.However,achieving high efficiency and selectivity in NitRR is fundamentally challenged by the complex lifecycle management of active hydrogen derived from water splitting.This review provides a timely and comprehensive analysis centered on the pivotal role and meticulous regulation of active hydrogen throughout the NitRR process.We first elucidate the distinct functions and characteristics of various hydrogen species,followed by a survey of advanced characterization techniques crucial for monitoring the dynamics of active hydrogen.Critically,three core strategies were systematically dissected to modulate the active hydrogen lifecycle:accelerating water activation and dissociation,enhancing the directional transport of hydrogen species,and precisely tuning active hydrogen coupling pathways while suppressing parasitic hydrogen evolution.By consolidating current understanding from both catalyst design and reaction mechanism perspectives,this review offers a hydrogen-centric roadmap and highlights emerging opportunities for rationally engineering advanced NitRR systems. 展开更多
关键词 Electrocatalytic nitrate reduction active hydrogen regulation Characterization methods Water activation and dissociation Promoting active hydrogen transfer Hydrogen evolution suppression
在线阅读 下载PDF
Functional macrocyclic arenes with active binding sites inside cavity for biomimetic molecular recognition
7
作者 Xixian Sun Shengke Li +1 位作者 Ruibing Wang Leyong Wang 《Chinese Chemical Letters》 2025年第4期1-2,共2页
Molecular recognition of bioreceptors and enzymes relies on orthogonal interactions with small molecules within their cavity. To date, Chinese scientists have developed three types of strategies for introducing active... Molecular recognition of bioreceptors and enzymes relies on orthogonal interactions with small molecules within their cavity. To date, Chinese scientists have developed three types of strategies for introducing active sites inside the cavity of macrocyclic arenes to better mimic molecular recognition of bioreceptors and enzymes.The editorial aims to enlighten scientists in this field when they develop novel macrocycles for molecular recognition, supramolecular assembly, and applications. 展开更多
关键词 supramolecular assembly orthogonal interactions introducing active sites active binding sites macrocyclic arenes molecular recognition orthogonal interactions small molecules biomimetic molecular recognition
原文传递
Research on Vibration Control of Pump Valve Pipeline System Based on Active Damping Device
8
作者 Hao-zhe Zhu Li-dong He Qing-wang Qin 《风机技术》 2025年第2期78-83,共6页
Pump valve pipeline vibration brings serious safety hazards to the operation of the equipment,for the pump valve system in the process of variable flow,variable speed,variable openings lead to excessive pipeline vibra... Pump valve pipeline vibration brings serious safety hazards to the operation of the equipment,for the pump valve system in the process of variable flow,variable speed,variable openings lead to excessive pipeline vibration.An active damping device(ADD)is used to the vibration of the pump valve pipeline system to apply the control force,to achieve the active control of the pipeline vibration.A pump-valve pipeline vibration test bench was built to compare the control effect of active damping device on pipeline vibration under different pump valve working conditions,and the results show that applying ADD control could effectively suppress the vibration of the pump valve pipeline and enhance the stability of the equipment during operation.At different pump operating rotation frequencies,the vibration amplitude of the pump valve pipeline in working frequency and its multiple frequencies are also effectively suppressed,with the maximum amplitude reduction of more than 60%.For the valve vibration caused by different operating openings,the vibration of the highest reduction of 68%,and the centrifugal pump drive shaft vi-bration reduced by up to 73%,which provides a new idea for vibration control of pump valve pipeline system. 展开更多
关键词 active Damping Device active Control ACTUATOR Pump Valve Pipeline
在线阅读 下载PDF
A Novel Feedforward Hybrid Active Noise Control System with Narrowband Frequency Adaptive Estimation and Error Separation
9
作者 PANG Mingrui LIU Yifei LIU Jian 《Transactions of Nanjing University of Aeronautics and Astronautics》 2025年第5期638-647,共10页
The conventional feedforward hybrid active noise control(FFHANC)system combines the advantages of the feedforward narrowband active noise control(FFNANC)system and the feedforward broadband active noise control(FFBANC... The conventional feedforward hybrid active noise control(FFHANC)system combines the advantages of the feedforward narrowband active noise control(FFNANC)system and the feedforward broadband active noise control(FFBANC)system.To enhance its adaptive adjustment capability under frequency mismatch(FM)conditions,this paper introduces a narrowband frequency adaptive estimation module into the conventional FFHANC system.This module integrates an autoregressive(AR)model and a linear cascaded adaptive notch filter(LCANF),enabling accurate reference signal frequency estimation even under significant FM.Furthermore,in order to improve the coherence between narrowband and broadband components in the system’s error signal and its corresponding control filter for the conventional FFHANC system,this paper proposes an algorithm based on autoregressive bandpass filter bank(AR-BPFB)for error separation.Simulation results demonstrate that the proposed FFHANC system maintains robust performance under high FM conditions and effectively suppresses hybrid-band noise.The AR-BPFB algorithm significantly elevates the convergence speed of the FFHANC system. 展开更多
关键词 active noise control feedforward hybrid active noise control(FFHANC)system autoregressive(AR)model linear cascaded adaptive notch filter(LCANF) bandpass filter bank(BPFB) error separation
在线阅读 下载PDF
Active flow control in aeronautic field and disease treatment in medical field
10
作者 Zhengyu ZUO Xin ZHANG 《Chinese Journal of Aeronautics》 2025年第11期1-4,共4页
Activeow control technology is a technique that controls the internaloweld of aircraft engines or theoweld around wings by means of disturbances induced by actuators,and adjusts the aerodynamic force and attitude of t... Activeow control technology is a technique that controls the internaloweld of aircraft engines or theoweld around wings by means of disturbances induced by actuators,and adjusts the aerodynamic force and attitude of the aircraft,so as to achieve the purposes of increasing lift,reducing drag,suppressing vibration and reducing noise.Hailed as an important source of innovative development for aircraft,this technology provides a new technical approach to solve the aerodynamic problems of aircraft,signicantly improve their comprehensive performance,break throughight boundaries,and promote disruptive innovation in the next generation of aircraft. 展开更多
关键词 aeronautical field disease treatment active flow control controls internaloweld adjusts aerodynamic force attitude aerodynamic problems activeow control technology aircraft engines
原文传递
Reactive voltage support strategy for droop-controlled grid-forming converters based on LADRC
11
作者 Dejian Yang Zhijie Cao Chaoquan Li 《iEnergy》 2025年第4期259-268,共10页
To enhance the low-voltage ride-through(LVRT)capability of emerging power systems with increasing penetration of renewable energy while addressing issues such as the slow response speed of traditional proportional-int... To enhance the low-voltage ride-through(LVRT)capability of emerging power systems with increasing penetration of renewable energy while addressing issues such as the slow response speed of traditional proportional-integral(PI)control,high model accuracy requirements,and complex system parameter tuning,this paper proposes a droop-controlled converter reactive power support strategy based on first-order linear active disturbance rejection control(LADRC).First,a mathematical model of a droop-controlled grid-forming(GFM)converter is established.A model equivalence method is then proposed to transform the dynamic characteristics of the control loop into equivalent impedance parameters.Based on the equivalent impedance parameter model,the influencing factors of the converter terminal voltage and point of common coupling(PCC)voltage are derived.Next,a first-order linear active disturbance rejection control strategy is introduced into the traditional droop control framework,and the controller parameters are optimized via the bandwidth tuning method.Finally,a simulation model of the droop-controlled GFM converter based on the linear active disturbance rejection controller is constructed on the PSCAD/EMTDC platform,and through comparative experiments under typical grid fault conditions,the effectiveness of the proposed control strategy in improving the system fault ride-through capability and voltage support is verified. 展开更多
关键词 Grid-forming control linear active disturbance rejection control reactive power support low-voltage ride-through
在线阅读 下载PDF
Intelligent marine waterborne epoxy coating based on functionalized multiscale nanocomposite:Mechanical enhancement,self-reporting,and active/passive anti-corrosion 被引量:3
12
作者 Hao Li Xian-Ze Meng +6 位作者 Hao-Jie Yan Run-Chao Zheng Hui-Song Hu Bing Lei Qin-Hao Zhang Lian-Kui Wu Fa-He Cao 《Journal of Materials Science & Technology》 2025年第18期68-83,共16页
Corrosion activities and related accidents are significant issues for marine facilities,leading to considerable economic losses.Waterborne epoxy(EP)coating has been seen as one of the optimal options for corrosion pro... Corrosion activities and related accidents are significant issues for marine facilities,leading to considerable economic losses.Waterborne epoxy(EP)coating has been seen as one of the optimal options for corrosion protection due to its stable properties and eco-friendliness(0 g/L volatile organic compounds).Nevertheless,several intrinsic deficiencies require improvement,such as fragile mechanical properties and defects(macro and micro),resulting in the continuous deterioration of comprehensive coating performances.In this work,a novel nanocomposite coating with mechanical enhancement,intelligent self-reporting,and active protection is fabricated by integrating the functionalized and compatible graphene oxide/cerium based metal-organic framework multiscale structure(GO-CeMOF-P/M).Notably,the homogenous dispersion of GO-CeMOF-P/M and its chemical interaction with the polymer matrix effectively reduces the defects resulting from solution volatilizing and enhances the compactness,which boosts the tensile strength(32.1 MPa/8.5%)and dry adhesion force(5.8 MPa)of the coating.Additionally,the controllable responsiveness and release of multiscale nanocomposite within external environments endow intelligent active protection and self-reporting characteristics for the GO-CeMOF-P/M-EP coating,making it especially suitable for a variety of practical marine applications.Furthermore,following immersion of 80 d in the aggressive environment,Zf=0.01 Hz value of GO-CeMOF-P/M-EP coating is 1.2×10^(10)Ωcm^(2),which is 164.4 times larger than that of EP coating(7.3×10^(7)Ωcm^(2)),demonstrating remarkably strengthened anti-corrosion ability.Consequently,by offering an intriguing design strategy,the current work anticipates addressing the inherent deficiencies of EP coating and facilitating its practicality and feasibility in real sea environments. 展开更多
关键词 Intelligent coating Graphene oxide Metal-organic framework active protection ANTI-CORROSION
原文传递
Regulation mechanism of active magnesium oxide on precipitation of lanthanum hydroxide 被引量:1
13
作者 Jianwei Zhao Haiqing Hao +4 位作者 Yanyan Zhao Meng Wang Xu Sun Zongyu Feng Xiaowei Huang 《Journal of Rare Earths》 2025年第6期1264-1271,I0007,共9页
Precipitation is often used for the preparation of La(OH)_(3)with precipitants of liquid alkali and ammonia.To solve the problems of high cost and wastewater pollution caused by common precipitants,the active MgO synt... Precipitation is often used for the preparation of La(OH)_(3)with precipitants of liquid alkali and ammonia.To solve the problems of high cost and wastewater pollution caused by common precipitants,the active MgO synthesized by pyrolysis was used as the precipitant to prepare La(OH)_(3).The species distribution of LaCl_(3)and LaCl_(3)-MgCl_(2)mixed system solution was calculated,and the kinetic analysis of the precipi-tation process was carried out to confirm the key factors influencing the precipitation of La(OH)_(3).The results show that La(OH)_(3)with D_(50)of 5.57μm,a specific surface area of 25.70 m^(2)/g,a rod-like shape,and MgO content of 0.044 wt%,was successfully prepared by adding active MgO.The precipitation ratio of La reaches 99.92%.The La(OH)_(3)precipitation is controlled by the diffusion process.The activity of MgO has a significant influence on MgO content in the precipitate.The preparation of La(OH)_(3)by active MgO provides a potential way for an eco-friendly preparation method of rare earth. 展开更多
关键词 active magnesium oxide PRECIPITATION Lanthanum hydroxide REGULATION Rare earths
原文传递
Advances and mechanisms of traditional Chinese medicine and its active ingredients against antibiotic-resistant Escherichia coli infections 被引量:1
14
作者 Shuo Yang Ping Su +2 位作者 Lu Li Shuang Liu Yi Wang 《Journal of Pharmaceutical Analysis》 2025年第2期375-388,共14页
In clinical practice,antibiotics have historically been utilized for the treatment of pathogenic bacteria.However,the gradual emergence of antibiotic resistance among bacterial strains has posed a significant challeng... In clinical practice,antibiotics have historically been utilized for the treatment of pathogenic bacteria.However,the gradual emergence of antibiotic resistance among bacterial strains has posed a significant challenge to this approach.In 2022,Escherichia coli,a Gram-negative bacterium renowned for its widespread pathogenicity and high virulence,emerged as the predominant pathogenic bacterium in China.The rapid emergence of antibiotic-resistant E.coli strains has rendered antibiotics insufficient to fight E.coli infections.Traditional Chinese medicine(TCM)has made remarkable contributions to the health of Chinese people for thousands of years,and its significant therapeutic effects have been proven in clinical practice.In this paper,we provide a comprehensive review of the advances and mechanisms of TCM and its active ingredients against antibiotic-resistant E.coli infections.First of all,this review introduces the classification,antibiotic resistance characteristics and mechanisms of E.coli.Then,the TCM formulas and extracts are listed along with their active ingredients against E.coli,including extraction solution,minimum inhibitory concentration(MIC),and the antibacterial mechanisms.In addition,there is growing evidence supporting the synergistic therapeutic strategy of combining TCM with antibiotics for the treatment of antibiotic-resistant E.coli infections,and we provide a summary of this evidence and its underlying mechanisms.In conclusion,we present a comprehensive review of TCM and highlight its potential and advantages in the prevention and treatment of E.coli infections.We hold the opinion that TCM will play an important role in global health,pharmaceutical development,and livestock farming in the future. 展开更多
关键词 Escherichia coli ANTIBIOTIC-RESISTANCE Traditional Chinese medicine active ingredients Antibacterial mechanism
暂未订购
Output feedback active disturbance rejection control of an electro-hydraulic servo system based on command filter 被引量:1
15
作者 Yanchun BAI Jianyong YAO +1 位作者 Jian HU Guangbin FENG 《Chinese Journal of Aeronautics》 2025年第2期214-225,共12页
The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses ... The output feedback active disturbance rejection control of a valve-controlled cylinder electro-hydraulic servo system is investigated in this paper.First,a comprehensive nonlinear mathematical model that encompasses both matched and mismatched disturbances is formulated.Due to the fact that only position information can be measured,a linear Extended State Observer(ESO)is introduced to estimate unknown states and matched disturbances,while a dedicated disturbance observer is constructed to estimate mismatched disturbances.Different from the traditional observer results,the design of the disturbance observer used in this study is carried out under the constraint of output feedback.Furthermore,an output feedback nonlinear controller is proposed leveraging the aforementioned observers to achieve accurate trajectory tracking.To mitigate the inherent differential explosion problem of the traditional backstepping framework,a finite-time stable command filter is incorporated.Simultaneously,considering transient filtering errors,a set of error compensation signals are designed to counter their negative impact effectively.Theoretical analysis affirms that the proposed control strategy ensures the boundedness of all signals within the closed-loop system.Additionally,under the specific condition of only time-invariant disturbances in the system,the conclusion of asymptotic stability is established.Finally,the algorithm’s efficacy is validated through comparative experiments. 展开更多
关键词 active disturbance rejection CONTROL Extended state observer Output feedback Disturbance observer Command filter
原文传递
Regulation Active Sites of Porous GaN Crystal Via Mn_(3)O_(4)Nanosheets for Advanced High Temperature Energy Storage 被引量:1
16
作者 Songyang Lv Shouzhi Wang +7 位作者 Qirui Zhang Lin Xu Ge Tian Jiaoxian Yu Guodong Wang Lili Li Xiangang Xu Lei Zhang 《Energy & Environmental Materials》 2025年第3期112-121,共10页
Gallium nitride(GaN)single crystal with prominent electron mobility and heat resistance have great potential in the high temperature integrate electric power systems.However,the sluggish charge storage kinetics and in... Gallium nitride(GaN)single crystal with prominent electron mobility and heat resistance have great potential in the high temperature integrate electric power systems.However,the sluggish charge storage kinetics and inadequate energy densities are bottlenecks to its practical application.Herein,the self-supported GaN/Mn_(3)O_(4) integrated electrode is developed for both energy harvesting and storage under the high temperature environment.The experimental and theoretical calculations results reveal that such integrated structures with Mn-N heterointerface bring abundant active sites and reconstruct low-energy barrier channels for efficient charge transferring,reasonably optimizing the ions adsorption ability and strengthening the structural stability.Consequently,the assembled GaN based supercapacitors deliver the power density of 34.0 mW cm^(-2) with capacitance retention of 81.3%after 10000 cycles at 130℃.This work innovatively correlates the centimeter scale GaN single crystal with ideal theoretical capacity Mn_(3)O_(4) and provides an effective avenue for the follow-up energy storage applications of the wide bandgap semiconductor. 展开更多
关键词 active sites density functional theory gallium nitride crystal high temperature SUPERCAPACITORS
在线阅读 下载PDF
Vibration reduction mechanism and characteristics evaluation of active elastic support/dry friction damper 被引量:1
17
作者 Siji WANG Dafang LIN +2 位作者 Quankun LI Jiayao CHEN Yuan LIU 《Chinese Journal of Aeronautics》 2025年第4期333-348,共16页
This paper studies the coupling mechanism between the nonlinear stiffness and damping coefficients of Active Elastic Support/Dry Friction Damper(AESDFD)and rotor system.First,parameters for evaluating the vibration re... This paper studies the coupling mechanism between the nonlinear stiffness and damping coefficients of Active Elastic Support/Dry Friction Damper(AESDFD)and rotor system.First,parameters for evaluating the vibration reduction characteristics are proposed to facilitate the design of the AESDFD.To achieve this,the nonlinear friction force is initially represented as equivalent stiffness and damping coefficients,based on the ball-plate friction model.Second,three evaluation parameters—optimal slipping displacement,loss factor,and controllability—are proposed to reveal the vibration reduction characteristics of the AESDFD,alongside determining the optimal normal force.Subsequently,the finite element method,in conjunction with the ball-plate friction model,is introduced to formulate the governing equation of a low-pressure rotor system equipped with AESDFDs.The steady-state responses of the AESDFDs-rotor system are solved using the harmonic balance method combined with an efficient iteration method.Finally,the solutions are validated on the AESDFDs-rotor system both numerically and experimentally.The results indicate that controllability effectively assesses the vibration reduction performance of the AESDFD and is relatively insensitive to variations in low normal force.Away from the critical speed,the AESDFD suppresses vibration by altering the resonance position of the rotor system through its stiffness coefficient.Near the critical speed,vibration reduction is achieved primarily through energy dissipation by the damping coefficient.If the loss factor is less than one,the stiffness coefficient can diminish the vibration reduction effect of the damping coefficient.Notably,the optimal normal force of the AESDFD achieves optimal vibration reduction effect.This study reveals that changes in rotor system unbalance do not affect the vibration reduction characteristics of the AESDFD,with the same upper limit to the vibration reduction effect of the AESDFD. 展开更多
关键词 active dry friction damper Low-pressure rotor system Vibration analysis Stiffness and damping coefficients Evaluation parameters Finite element method
原文传递
A PCM-based active temperature-preserved coring method for deep sea natural gas hydrate 被引量:1
18
作者 Han Wu Yunqi Hu +4 位作者 Chenghang Fu Ling Chen Zhiqiang He Meng Xu Heping Xie 《International Journal of Mining Science and Technology》 2025年第11期1939-1954,共16页
Natural gas hydrate(NGH)has a bright future as a clean energy source with huge reserves.Coring is one of the most direct methods for NGH exploration and research.Preserving the in-situ properties of the core as much a... Natural gas hydrate(NGH)has a bright future as a clean energy source with huge reserves.Coring is one of the most direct methods for NGH exploration and research.Preserving the in-situ properties of the core as much as possible during the coring process is crucial for the assessment of NGH resources.However,most existing NGH coring techniques cannot preserve the in-situ temperature of NGH,leading to distortion of the physical properties of the obtained core,which makes it difficult to effectively guide NGH exploration and development.To overcome this limitation,this study introduces an innovative active temperature-preserved coring method for NGH utilizing phase change materials(PCM).An active temperature-preserved corer(ATPC)is designed and developed,and an indoor experimental system is established to investigate the heat transfer during the coring process.Based on the experimental results under different environment temperatures,a heat transfer model for the entire ATPC coring process has been established.The indoor experimental results are consistent with the theoretical predictions of the heat transfer model,confirming its validity.This model has reconstructed the temperature changes of the NGH core during the coring process,demonstrating that compared to the traditional coring method with only passive temperature-preserved measures,ATPC can effectively reduce the core temperature by more than 5.25℃.With ATPC,at environment temperatures of 15,20,25,and 30℃,the duration of low-temperature state for the NGH core is 53.85,32.87,20.32,and 11.83 min,respectively.These findings provide new perspectives on temperature-preserving core sampling in NGH and provide technical support for exploration and development in NGH. 展开更多
关键词 Deep sea coring Natural gas hydrate active temperature-preserved method Phase change material
在线阅读 下载PDF
Overview on active disturbance rejection control for electro-mechanical actuation servo drive 被引量:1
19
作者 Chunqiang LIU Guangzhao LUO +1 位作者 Zhe CHEN Xiaofeng DING 《Chinese Journal of Aeronautics》 2025年第7期291-309,共19页
Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical... Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical arms.The performance of the servo drive,which encompasses the response to the torque,efficiency,control bandwidth and the steady-state positioning accuracy,significantly influences the performance of the aviation actuation.Consequently,enhancing the control bandwidth and refining the positioning accuracy of aviation electro-mechanical actuation servo drives have emerged as a focal point of research.This paper investigates the multi-source disturbances present in aviation electro-mechanical actuation servo systems and summarizes recent research on high-performance servo control methods based on active disturbance rejection control(ADRC).We present a comprehensive overview of the research status pertaining to servo control architecture,strategies for suppressing disturbances in the current loop,and ADRC-based strategies for the position loop.We delineate the research challenges and difficulties encountered by aviation electro-mechanical actuation servo drive control technology. 展开更多
关键词 active disturbance rejection control Electric servo drive Permanent magnet synchronous motor Electro-mechanical actuation
原文传递
Methods for the formation of M-N_(x)-C active sites on single-atom catalysts and their role in persulfate activation by non-radical paths
20
作者 SI Wen-hao SI Jin-xuan +4 位作者 WANG Kang-jun QI Fei CHEN Jia-bin ZENG Ze-quan HUANG Zhang-gen 《新型炭材料(中英文)》 北大核心 2025年第5期993-1015,共23页
In recent years,numer-ous single-atom catalysts(SACs)have been synthesized to activate persulfate(PS)by a non-radical pathway because of its high se-lectivity,and activity for the cata-lyst.Metal-nitrogen-carbon(M-N_(... In recent years,numer-ous single-atom catalysts(SACs)have been synthesized to activate persulfate(PS)by a non-radical pathway because of its high se-lectivity,and activity for the cata-lyst.Metal-nitrogen-carbon(M-N_(x)-C)has been identified as the key active site in SACs.Although methods for preparing SACs have been extensively reported,a systematic summary of the direct construction of M-N_(x)-C,espe-cially unconventional metal-nitrogen-carbon(UM-N_(x)-C,x≠4),on SACs for PS non-radical activation has still not been reported.The role of the M-N_(x)-C active sites on PS non-radical activation is discussed and methods for the formation of M-N_(x)-C and UM-N_(x)-C active sites in SACs and the effect of catalyst carriers such as carbon nitride(g-C_(3)N_(4)),MOFs,COFs,and other car-bon materials are reviewed.Direct and indirect methods,especially for UM-N_(x)-C active site formation,are also elaborated.Factors affecting the formation of a M-N_(x)-C active site on SACs are also discussed.Prospects for the use of M-N_(x)-C active sites for the non-radical activation of PS by SACs to remove organic contaminants from wastewater are evaluated. 展开更多
关键词 Single-atom catalysts PERSULFATE Non-radical pathway Unconventional metal-nitrogen-carbon active site Organic contaminants
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部