检索结果-南通市图书馆

Low-Frequency Stability Analysis of Power Electronic Traction Transformer Based Train-Network System

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2024年第4期10卷 1608-1617页

作者： Yi Hong yang li Zhikang Shuai Hanyu yang College of Electrical and Information Engineering Hunan University and the Advanced Energy Technology Center of State Grid Shanghai Energy Interconnection Research Institute Co.Ltd.Shanghai 201203China College of Electrical and Information Engineering Hunan UniversityChangsha 410082China College of Electrical Engineering and Controal Science in Nanjing Tech University Nanjing 211816China

Power electronic traction transformers(PETTs)will be increasingly applied to locomotives in the future for their small volume and light ***,similar to conventional trains,PETTs behave as constant power loads and may cause low-frequency oscillation(LFO)to the train-network *** solve this issue,a mathematical model of the PETT is firstly proposed and verified based on the extended describing function(EDF)method in this *** the proposed model,the LLC converter is simplified to an equivalent circuit consisting of a capacitor and a resistor in *** is further demonstrated that the model can apply to various LLC converters with different topologies and ***,when the parameter differences between cells are not obvious,the PETT can be simplified to a single-phase rectifier(i.e.,conventional train)by equivalent *** on the model of PETT,the system low-frequency stability and influential factors are analyzed by using the generalized Nyquist ***,the correctness and accuracy of theoretical analyses are validated by off-line and hardware-in-the-loop simulation results.

关键词： Extended describing function method impedance model low-frequency oscillation power electronic traction transformer train-network system

Simultaneously Improved Curing,Mechanical,Antioxidative Properties and Reduced ZnO Loading of Silica Filled NR Composites by Incorporation of Low-cost Crude Carbon Dots via Conventional Melt-milling Method

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第6期42卷 815-825页

作者： chao-Ying Sun Hai-Jun Ji li-Wei li Hui yang Xiao-Peng An Yi-Ping Chen Ming-Jian Han Can Jiang li-Qun Zhang Peng Yu Run-Guo Wang State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing100029China School of Materials Science and Engineering Wuhan Institute of TechnologyWuhan430205China

Rubbers or elastomers play an important role in hi-tech technology and civilian daily life because of their unique and strategical ***,the rubber additives are essential components for rubbers’practical ***,developing novel multifunctional additives has attracted increasing research *** this work,low-cost crude carbon dots(CCDs)were used as multifunctional additives for natural rubber/silica system(without any additional modification)through industrial compatible melt-mixing *** results revealed that the CCDs could disperse well in the NR/silica system,and they could not only endow the rubber compound with excellent anti-aging capability due to CCDs’radical scavenging activity because of their plenty of nitrogen-containing species,but also improve the curing rate and mechanical performance of the rubber ***,the CCDs could reduce the rolling resistance of the rubber composites(tanδvalue at 7%strain of the rubber composite could be decreased by 34%),which is promising for the application of energy-saving tire ***,the addition of CCDs could effectively reduce the ZnO dosage by at least 40%in the rubber composite without deteriorating its ***,this work provides valuable guidance to develop novel cheap yet effective additives for the elastomer.

关键词： Natural rubber Crude carbon dots Antioxidant ZnO reduction Vulcanization

Enhancing force sensing in a squeezed optomechanical system with quantum nondemolition measurement

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第1期76卷 49-60页

作者： Shi-Lei chao Zi-Hao li Xin-You Lü School of Physics Huazhong University of Science and Technology430074 WuhanChina

A theoretical scheme is proposed to enhance the sensitivity of force sensors with quantum nondemolition measurement(QND)in an optomechanical setup assisted by four-tone optical driving and an optical parametric amplifier(OPA).With the help of special drive,the system can be simplified as the typical type of QND for force sensing,so that the backaction noise can be evaded to surpass the standard quantum ***,the added noise can be suppressed owing to the modified optical susceptibility resulting from the *** introducing two oscillators coupling with two charged bodies respectively,the signal can be enhanced with the nonlinearity caused by Coulomb interaction,while the noise presents an exponential ***,considering the homodyne detection effect,the range of system parameters and frequency bands will be *** present investigation may provide a route toward simultaneously evading backaction noise,reducing the mechanical thermal noise,and enhancing the external signal,which can be an alternative design for sensitive devices.

关键词： force sensing optical parametric amplifier quantum non-demolition measurement optomechanical system

River width and depth as key factors of diurnal activity energy expenditure allocation for wintering Spot-billed Ducks in the Xin'an River Basin

在线全文

学校读者我要写书评

暂无评论

Avian Research 2024年第1期15卷 116-122页

作者： chao Yu Xuying Lu Deli Sun Mengnan Chu Xueyun li Qun li College of life and Environmental Sciences Huangshan UniversityHuangshan245021China Environment Conservation Research Centre of Xin’an River Basin Huangshan UniversityHuangshan 245021China Department of Resources Conservation Southern Anhui National Wildlife Rescue CenterXiuning 245400China

Rivers are important habitats for wintering ***,they are easily influenced by natural and human *** important approach for waterbirds to adapt to habitats is adjusting the activity time and energy expenditure allocation of diurnal *** compensatory foraging hypothesis predicts that increased energy expenditure leads to longer foraging time,which in turn increases food intake and helps maintain a constant energy ***,it is unclear whether human-disturbed habitats result in increased energy expenditure related to safety or *** this study,the scan sample method was used to observe the diurnal behavior of the wintering Spot-billed Duck(Anas poecilorhyncha) in two rivers in the Xin’an River Basin from October 2021 to March *** allocation of time and energy expenditure for activity in both normal and disturbed environments was *** results showed that foraging accounted for the highest percentage of time and energy ***,foraging decreased in the disturbed environment than that in the normal *** behavior showed the opposite trend,while other behaviors were similar in both *** total diurnal energy expenditure of ducks in the disturbed environment was greater than that in the normal environment,with decreased foraging and resting time percentage and increased behaviors related to immediate safety(swimming and alert) and *** results oppose the compensatory foraging hypothesis in favor of increased *** optimal diurnal energy expenditure model included river width and water depth,which had a positive relationship;an increase in either of these two factors resulted in an increase in energy *** study provides a better understanding of energy allocation strategies underlying the superficial time allocation of wintering waterbirds according to environmental *** these changes can help understand the maximum fitness of wi

关键词： Diurnal behavior activities River factors Time and energy expenditure allocation Wintering Spot-billed Duck Xin’an River Basin

A universal performance-enhancing method for li-S batteries:the cathode material of li_(2)S@li_(2)S_(2)@li_(2)S_(6) double-shell structure

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第4期67卷 1229-1241页

作者： Shunjin yang Yujiang Sun Qiaran Zhang Xiaohu Hu Xing Chen Guoran li Xiao Sun Yuzhe Zhang Shijie Xu Xinyu Wang Yongan yang Institute of Molecular Plus School of Chemical Engineering and TechnologyTianjin UniversityTianjin 300072China College of Materials Science and Engineering Nankai UniversityTianjin 300350China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China Tianjin Key Laboratory of Advanced Carbon and Electrochemical Energy Storage Tianjin 300072China

lithium sulfide(li_(2)S)as a cathode material for lithium-sulfur(li-S)batteries,one of the most promising advanced batteries in the future,has received tremendous attention in the past ***,developing the practical li_(2)S cathode confronts challenges of low conductivity for li-ions and electrons,high sensitivity to environmental moisture,big overpotential barrier to electrochemical activation,and poor cyclability due to the shuttle effect of intermediate *** article herein reports a simple and effective strategy for making li_(2)S@li_(2)S_(2)@li_(2)S_(6) double-shelled microparticles,which can significantly mitigate these *** are synthesized by dissolving li2S together with S in dimethoxyethane,then drying off the solvent,and finally calcining the collected *** with pure li_(2)S,such a double-shell material presents a 26.7% improvement in cycling capacity,0.5 V lower in activation overpotential,and prolonged tolerance in the ambient *** density functional theory calculation shows that the performance enhancement lies in the higher stability of li2S6in contact with moisture and some autocatalytic effect of li_(2)S_(2)@li_(2)S_(6).Such a double-shell structure becomes a universal performanceenhancing approach when being combined with other means,such as cathodes composited with catalytic MoS_(2),separators modified with selenium-doped sulfurized-polyacrylonitrile/montmorillonite,electrolytes containing fluorenone additive,and li anodes coated with a layer of li_(3)*** corresponding capacity retention shows up to 80%improvement compared with pure li_(2)S.

关键词： lithium-sulfur batteries lithium sulfide lithium polysulfides cathode performance double shell structure

Vision-based survey method for extraordinary loads on buildings

在线全文

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2024年第6期18卷 815-831页

作者： yang li Jun CHEN Pengcheng WANG College of Civil Engineering Tongji UniversityShanghai 200092China China United Engineering Co.Ltd. Hangzhou 310052China State Key Laboratory of Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Shanghai Key Laboratory of Engineering Structure Safety Shanghai Research Institute of Building Sciences Co.Ltd.Shanghai 200032China

The statistical modeling of extraordinary loads on buildings has been stagnant for decades due to the laborious and error-prone nature of existing survey methods,such as questionnaires and verbal *** study proposes a new vision-based survey method for collecting extraordinary load data by automatically analyzing surveillance *** this purpose,a crowd head tracking framework is developed that integrates crowd head detection and reidentification models based on convolutional neural networks to obtain head trajectories of the crowd in the survey *** crowd head trajectories are then analyzed to extract crowd quantity and velocities,which are the essential factors for extraordinary *** survey areas with frequent crowd movements during temporary events,the equivalent dynamic load factor can be further estimated using crowd velocity to consider dynamic effects.A crowd quantity investigation experiment and a crowd walking experiment are conducted to validate the proposed survey *** experimental results prove that the proposed survey method is effective and accurate in collecting load data and reasonable in considering dynamic effects during extraordinary *** proposed survey method is easy to deploy and has the potential to collect substantial and reliable extraordinary load data for determining design load on buildings.

关键词： load survey extraordinary load live load object detection multiple-object tracking

Data Driven Vibration Control:A Review

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第9期11卷 1898-1917页

作者： Weiyi yang Shuai li Xin Luo Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714 Chongqing School University of Chinese Academy of SciencesChongqing 400714China Faculty of Information Technology and Electrical Engineering University of OuluOulu 90570 VTT-Technology Research Center of Finland Oulu 90570Finlan College of Computer and Information Science Southwest UniversityChongqing 400715China

With the ongoing advancements in sensor networks and data acquisition technologies across various systems like manufacturing,aviation,and healthcare,the data driven vibration control(DDVC)has attracted broad interests from both the industrial and academic *** shaping(IS),as a simple and effective feedforward method,is greatly demanded in DDVC *** convolves the desired input command with impulse sequence without requiring parametric dynamics and the closed-loop system structure,thereby suppressing the residual vibration *** on a thorough investigation into the state-of-the-art DDVC methods,this survey has made the following efforts:1)Introducing the IS theory and typical input shapers;2)Categorizing recent progress of DDVC methods;3)Summarizing commonly adopted metrics for DDVC;and 4)Discussing the engineering applications and future trends of *** doing so,this study provides a systematic and comprehensive overview of existing DDVC methods from designing to optimizing perspectives,aiming at promoting future research regarding this emerging and vital issue.

关键词： Data driven vibration control(DDVC) data science designing method feedforward control industrial robot input shaping optimizing method residual vibration

Advancements in the modification of magnesium-based hydrogen storage materials

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2024年第3期34卷 540-554页

作者： lin yang Wen Zeng Yanqiong li College of Materials Science and Engineering Chongqing University School of Electronic Information & Electrical Engineering Chongqing University of Arts and Sciences

Magnesium-based hydrogen storage materials represent a hydrogen storage technology with broad application prospects. As the global energy crisis and environmental pollution issues become increasingly severe, hydrogen,as a clean and efficient energy source, has garnered growing attention. Magnesium-based hydrogen storage,serving as a crucial means for storing and transporting hydrogen, is gaining prominence due to its abundant resources, low cost, low density, and high hydrogen storage density. However, challenges in terms of absorption/desorption rates, temperature, activation energy, and enthalpy during hydrogen application impede its development. To address these challenges, this paper systematically reviews current research on magnesium-based hydrogen storage materials, encompasses their types, characteristics, and hydrogen absorption ***, it delves into the impacts of nanoscale dimensions, alloying, doping, and catalysis on the performance of magnesium-based materials. The aim is to provide valuable insights for research in related fields.

关键词： For hydrogen storage Magnesium-based materials Research on modifying

Repair tolerance assessment for aircraft composite structures using Bayesian updating

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第6期37卷 360-391页

作者： Xin li Hongfu ZUO Bin yang School of Automotive and Rail Transit Nanjing Institute of TechnologyNanjing 211167China Civil Aviation Key Laboratory of Aircraft Health Monitoring and Intelligent Maintenance College of Civil AviationNanjing University of Aeronautics and AstronauticsNanjing 211106China

Detection and repair of composite damage is crucial to ensure the safety and reliability of aircraft structures.A novel approach to quantitatively evaluate the repair tolerance of composite structures in civil aircraft based on Bayesian updating is *** method incorporates historical damage inspection data to determine the prior distribution of damage size,which is then updated with newly collected damage size data using Bayesian *** Carlo simulation is employed to investigate the probability of failure and estimate maintenance costs,considering various factors such as the frequency and timing of damage events,damage detection,structural strength,gust loads,and maintenance expenses throughout the lifecycle of composite *** and economic factors are considered to establish a lower threshold for repairs and an upper threshold for maintenance based on the occurrence of accidental impact *** of the effectiveness and feasibility of a quantitative assessment method for repair tolerance is conducted using damage statistics data from civil aircraft routes utilizing the structural skin panels of composite outer *** results demonstrate that the method proposed in conjunction with extensive simulations and full utilization of field damage inspection data can effectively simulate unexpected impact damage situations that may occur during civil aircraft service and evaluate the reliability and economic feasibility of the repair of *** research findings hold significant theoretical and practical value for the preparation of documents for continued airworthiness of composite structures,including structural repair manuals and maintenance programs.

关键词： Composite structures Repair tolerance Maintenance Bayesian updating Probability of failure