The paper has introduced the Journal 'Advanced Technology of Electrical Engineering and Energy',presented its main journal evaluation indexes. The result indicates that the journal has made great progress in r...The paper has introduced the Journal 'Advanced Technology of Electrical Engineering and Energy',presented its main journal evaluation indexes. The result indicates that the journal has made great progress in recent years. It gives much info. about the journal to authors.展开更多
This article describes an Internet based laboratory (NETLAB) developed at Zhejiang University for electrical engi- neering education. A key feature of the project is the use of real experimental systems rather than si...This article describes an Internet based laboratory (NETLAB) developed at Zhejiang University for electrical engi- neering education. A key feature of the project is the use of real experimental systems rather than simulation or virtual reality. NELTAB provides remote access to a wide variety of experiments, including not only basic electrical and electronic experiments but also many innovative control experiments. Students can effectively use the laboratory at any time and from anywhere. NETLAB has been in operation since July 2003.展开更多
The paper presented the statistics and analysis on papers published on the journal 'Advanced Technology of Electrical Engineering and Energy' from 1996 to 2008: the paper acceptance rate,the paper category,the...The paper presented the statistics and analysis on papers published on the journal 'Advanced Technology of Electrical Engineering and Energy' from 1996 to 2008: the paper acceptance rate,the paper category,the first author's affiliations,the top 7 first authors,the top 10 coauthors and also the journal evaluation indexes of the journal.It offers details of the journal to anyone interested,especially to our editorial board and our broad readers.展开更多
The paper has introduced the journals on electrical engineering in China in detail, presented its publication year, the distributions for all elec. eng. journals and its core journals, the position and level of the jo...The paper has introduced the journals on electrical engineering in China in detail, presented its publication year, the distributions for all elec. eng. journals and its core journals, the position and level of the journals, its main journal evaluation indexes, its core journal proportion and inclusion info. by famous international database. The paper offers much information about the journals on electrical engineering in China to readers, and also points out present problems and gives suggestion.展开更多
The human brain is asymmetrical in function, with each of its two hemispheres being somewhat responsible for distinct cognitive and motor tasks, to include writing. It stands to reason that engineering students who ha...The human brain is asymmetrical in function, with each of its two hemispheres being somewhat responsible for distinct cognitive and motor tasks, to include writing. It stands to reason that engineering students who have established entrance into their upper-division programs will have demonstrated cognitive proficiency in math and logical operations, abstract and analytical reasoning and language usage, to include writing. In this study the question was asked: is there a correlation between an upper-division electrical engineering students’ analytical reasoning ability and their descriptive writing ability? Descriptive writing is taken here to mean a students’ ability to identify key physical aspects of a mathematical model and to express—in words—a concise and well-balanced description that demonstrates a deep conceptual understanding of the model. This includes more than a description of the variables or the particular application to an engineering problem;it includes a demonstrated recognition of the basic physics that govern the model, certain limitations (idealizations) inherent in the model, and an understanding of how to make practical experimental measurements to verify the governing physics in the model. A student at this level may demonstrate proficiency in their analytical reasoning skills and hence be capable of correctly solving a given problem. However, this does not guarantee that the same student is skilled in associating equations with their physical meaning on a deep conceptual level or in understanding physical limitations of the equation. Consequently, such a student may demonstrate difficulty in mapping their comprehension of the model into written language that demonstrates a sound conceptual understanding of the governing physics. The findings represent a sample of two independent class sections of Electrical and Computer Engineering junior’s first course in Microe-lectronic Devices and Circuits during fall semesters 2012 and 2013 at a private mid-size university in NW Oregon. A total of three exams were administered to each of the 2012/2013 groups. Correlations between exam scores that students achieved on their descriptive writing of microelectronics phenomena and their analytical problem-solving abilities were examined and found to be quite significant.展开更多
Graphene(Gr)has unique properties including high electrical conductivity;Thus,graphene/copper(Gr/Cu)composites have attracted increasing attention to replace traditional Cu for electrical applications. However,the pro...Graphene(Gr)has unique properties including high electrical conductivity;Thus,graphene/copper(Gr/Cu)composites have attracted increasing attention to replace traditional Cu for electrical applications. However,the problem of how to control graphene to form desired Gr/Cu composite is not well solved. This paper aims at exploring the best parameters for preparing graphene with different layers on Cu foil by chemical vapor deposition(CVD)method and studying the effects of different layers graphene on Gr/Cu composite’s electrical conductivity. Graphene grown on single-sided and double-sided copper was prepared for Gr/Cu and Gr/Cu/Gr composites. The resultant electrical conductivity of Gr/Cu composites increased with decreasing graphene layers and increasing graphene volume fraction. The Gr/Cu/Gr composite with monolayer graphene owns volume fraction of less than 0.002%,producing the best electrical conductivity up to59.8 ×10^(6)S/m,equivalent to 104.5% IACS and 105.3% pure Cu foil.展开更多
Ni-rich layered oxides are potential cathode materials for next-generation high energy density Li-ion batteries due to their high capacity and low cost.However,the inherently unstable surface properties,including high...Ni-rich layered oxides are potential cathode materials for next-generation high energy density Li-ion batteries due to their high capacity and low cost.However,the inherently unstable surface properties,including high levels of residual Li compounds,dissolution of transition metal cations,and parasitic side reactions,have not been effectively addressed,leading to significant degradation in their electrochemical performance.In this study,we propose a simple and effective lactic acid-assisted interface engineering strategy to regulate the surface chemistry and properties of Ni-rich LiNi_(0.8)Co_(0.1)Mr_(0.1)O_(2) cathode.This novel surface treatment method successfully eliminates surface residual Li compounds,inhibits structural collapse,and mitigates cathode-electrolyte interface film growth.As a result,the lactic acidtreated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) achieved a remarkable capacity retention of 91.7% after 100 cycles at 0.5 C(25℃) and outstanding rate capability of 149.5 mA h g^(-1) at 10 C,significantly outperforming the pristine material.Furthermore,a pouch-type full cell incorporating the modified LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode demonstrates impressive long-term cycle life,retaining 81.5% of its capacity after 500 cycles at 1 C.More importantly,the thermal stability of the modified cathode is also dramatically improved.This study offers a valuable surface modification strategy for enhancing the overall performance of Ni-rich cathode materials.展开更多
In contrast to conventional transformers, power electronic transformers, as an integral component of new energy power system, are often subjected to high-frequency and transient electrical stresses, leading to heighte...In contrast to conventional transformers, power electronic transformers, as an integral component of new energy power system, are often subjected to high-frequency and transient electrical stresses, leading to heightened concerns regarding insulation failures. Meanwhile, the underlying mechanism behind discharge breakdown failure and nanofiller enhancement under high-frequency electrical stress remains unclear. An electric-thermal coupled discharge breakdown phase field model was constructed to study the evolution of the breakdown path in polyimide nanocomposite insulation subjected to high-frequency stress. The investigation focused on analyzing the effect of various factors, including frequency, temperature, and nanofiller shape, on the breakdown path of Polyimide(PI) composites. Additionally, it elucidated the enhancement mechanism of nano-modified composite insulation at the mesoscopic scale. The results indicated that with increasing frequency and temperature, the discharge breakdown path demonstrates accelerated development, accompanied by a gradual dominance of Joule heat energy. This enhancement is attributed to the dispersed electric field distribution and the hindering effect of the nanosheets. The research findings offer a theoretical foundation and methodological framework to inform the optimal design and performance management of new insulating materials utilized in high-frequency power equipment.展开更多
Antimony(Sb)-ba sed anode materials are feasible candidates for sodium-ion batteries(SIBs) due to their high theoretical specific capacity and excellent electrical conductivity.However,they still suffer from volume di...Antimony(Sb)-ba sed anode materials are feasible candidates for sodium-ion batteries(SIBs) due to their high theoretical specific capacity and excellent electrical conductivity.However,they still suffer from volume distortion,structural collapse,and ionic conduction interruption upon cycling.Herein,a hierarchical array-like nanofiber structure was designed to address these limitations by combining architecture engineering and anion tuning strategy,in which SbPO_(4-x) with oxygen vacancy nanosheet arrays are anchored on the surface of interwoven carbon nanofibers(SbPO_(4-x)@CNFs).In particular,bulky PO_(4)^(3-) anions mitigate the large volume distortion and generate Na_(3)PO_(4) with high ionic conductivity,collectively improving cyclic stability and ionic transport efficiency.The abundant oxygen vacancies substantially boost the intrinsic electronic conductivity of SbPO_4,further accelerating the reaction dynamics.In addition,hierarchical fibrous structures provide abundant active sites,construct efficient conducting networks,and enhance the electron/ion transport capacity.Benefiting from the advanced structural design,the SbPO_(4-x)@CNFs electrodes exhibit outstanding cycling stability(1000 cycles at 1.0 A g^(-1) with capacity decay of 0.05% per cycle) and rapid sodium storage performance(293.8 mA h g^(-1) at 5.0 A g^(-1)).Importantly,systematic in-/ex-situ techniques have revealed the "multi-step conversion-alloying" reaction process and the "battery-capacitor dual-mode" sodium-storage mechanism.This work provides valuable insights into the design of anode materials for advanced SIBs with elevated stability and superior rate performance.展开更多
The current existing problem of deep learning framework for the detection and segmentation of electrical equipment is dominantly related to low precision.Because of the reliable,safe and easy-to-operate technology pro...The current existing problem of deep learning framework for the detection and segmentation of electrical equipment is dominantly related to low precision.Because of the reliable,safe and easy-to-operate technology provided by deep learning-based video surveillance for unmanned inspection of electrical equipment,this paper uses the bottleneck attention module(BAM)attention mechanism to improve the Solov2 model and proposes a new electrical equipment segmentation mode.Firstly,the BAM attention mechanism is integrated into the feature extraction network to adaptively learn the correlation between feature channels,thereby improving the expression ability of the feature map;secondly,the weighted sum of CrossEntropy Loss and Dice loss is designed as the mask loss to improve the segmentation accuracy and robustness of the model;finally,the non-maximal suppression(NMS)algorithm to better handle the overlap problem in instance segmentation.Experimental results show that the proposed method achieves an average segmentation accuracy of mAP of 80.4% on three types of electrical equipment datasets,including transformers,insulators and voltage transformers,which improve the detection accuracy by more than 5.7% compared with the original Solov2 model.The segmentation model proposed can provide a focusing technical means for the intelligent management of power systems.展开更多
The connection and interaction between the eye and the brain are crucial to understanding brain disorders(Marchesi et al.,2021).Both the eye and the brain have a limited regenerative capacity as there are few progenit...The connection and interaction between the eye and the brain are crucial to understanding brain disorders(Marchesi et al.,2021).Both the eye and the brain have a limited regenerative capacity as there are few progenitor cells,and nerve cells do not replicate.Hence,neurodegeneration implicates irreversible damage to the central nervous system,as observed in several neurodegenerative diseases(Marchesi et al.,2021).展开更多
Under the background of new engineering,the reform of the comprehensive practical course system for mechanical and electronic engineering majors actively responds to the challenges posed by the new round of technologi...Under the background of new engineering,the reform of the comprehensive practical course system for mechanical and electronic engineering majors actively responds to the challenges posed by the new round of technological revolution and industrial transformation to higher education,cultivating top-notch innovative intellectuals with comprehensive engineering qualities,meeting the requirements of being able to solve complex engineering problems rather than just cognitive capabilities,forming two core courses through reconstructing and reshaping the core courses of the major.The core courses include Drive,Measurement,and Control I and Drive,Measurement,and Control II,which highlight the comprehensive framework of mechanical and electronic engineering professional knowledge,continuing the comprehensive practical course system based on the unity of knowledge and practice,following the trend of new engineering,highlighting the practicality of professional innovation,assisting engineering education reform,and promoting high-quality development of new engineering professionals cultivation.展开更多
Based on,but not limited to the research results of electrical engineering published in the special issue of Science in China Series E,June 2008,this essay gives a brief review on a wide range of state-of-art advancem...Based on,but not limited to the research results of electrical engineering published in the special issue of Science in China Series E,June 2008,this essay gives a brief review on a wide range of state-of-art advancement in electrical engineering field of China,which includes power system modeling,analysis and control,risk assessments in power system,etc.展开更多
A novel three-phase traction power supply system is proposed to eliminate the adverse effects caused by electric phase separation in catenary and accomplish a unifying manner of traction power supply for rail transit....A novel three-phase traction power supply system is proposed to eliminate the adverse effects caused by electric phase separation in catenary and accomplish a unifying manner of traction power supply for rail transit.With the application of two-stage three-phase continuous power supply structure,the electrical characteristics exhibit new features differing from the existing traction system.In this work,the principle for voltage levels determining two-stage network is dissected in accordance with the requirements of traction network and electric locomotive.The equivalent model of three-phase traction system is built for deducing the formula of current distribution and voltage losses.Based on the chain network model of the traction network,a simulation model is established to analyze the electrical characteristics such as traction current distribution,voltage losses,system equivalent impedance,voltage distribution,voltage unbalance and regenerative energy utilization.In a few words,quite a lot traction current of about 99%is undertaken by long-section cable network.The proportion of system voltage losses is small attributed to the two-stage three-phase power supply structure,and the voltage unbal-ance caused by impedance asymmetry of traction network is less than 1‰.In addition,the utilization rate of regenerative energy for locomotive achieves a significant promotion of over 97%.展开更多
Refractory high-entropy alloys(RHEAs)have promising applications as the new generation of hightemperature alloys in hypersonic vehicles,aero-engines,gas turbines,and nuclear power plants.This study focuses on the micr...Refractory high-entropy alloys(RHEAs)have promising applications as the new generation of hightemperature alloys in hypersonic vehicles,aero-engines,gas turbines,and nuclear power plants.This study focuses on the microstructures and mechanical properties of the NbMoTaW(HfN)_(x)(x=0,0.3,0.7,and 1.0)RHEAs.The alloys consist of multiple phases of body-centered cubic(BCC),hafnium nitride(HfN),or multicomponent nitride(MN)phases.As the x contents increase,the grain size becomes smaller,and the strength gradually increases.The compressive yield strengths of the NbMoTaWHfN RHEA at ambient temperature,1000,1400,and 1800℃ were found to be 1682,1192,792,and 288 MPa,respectively.The high-temperature strength of this alloy is an inspiring result that exceeds the high temperature and strength of most known alloys,including high-entropy alloys,refractory metals,and superalloys.The HfN phase has a significant effect on strengthening due to its high structural stability and sluggish grain coarsening,even at ultra-high temperatures.Its superior properties endow the NbMoTaWHfN RHEA with potential for a wide range of engineering applications at ultra-high temperatures.This work offers a strategy for the design of high-temperature alloys and proposes an ultra-high-temperature alloy with potential for future engineering applications.展开更多
The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated.This model consists of a shunt nonlinear resistance–capacitance(J(V)–C(V)) circuit and a series ...The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated.This model consists of a shunt nonlinear resistance–capacitance(J(V)–C(V)) circuit and a series resistance–inductance(R–L) circuit. Through linear dispersion analysis, two features of the network are found, that is, low bandpass and bandpass filter characteristics. The effects of the conductance’s parameter λ on the linear dispersion curve are also analyzed. It appears that an increase of λ induces a decrease(an increase) of the width of the bandpass filter for positive(negative) values of λ. By applying the reductive perturbation method, we derive the equation governing the dynamics of the modulated waves in the system. This equation is the well-known nonlinear Schr?dinger equation extended by a linear term proportional to a hybrid parameter σ, i.e., a dissipation or amplification coefficient. Based on this parameter, we successfully demonstrate the hybrid behavior(dissipation and amplification) of the system. The exact and approximate solitary wave solutions of the obtained equation are derived, and the effects of the coefficient σ on the characteristic parameters of these waves are investigated. Using the analytical solutions found, we show numerically that the waves that are propagated throughout the system can be dissipated, amplified, or remain stable depending on the network parameters. These results are not only in agreement with the analytical predictions, but also with the existing experimental results in the literature.展开更多
The Fundamentals of Combustion course is an important compulsory course for Energy and Power Engineering Majors under the background of carbon peaking.According to the characteristics of teaching and scientific resear...The Fundamentals of Combustion course is an important compulsory course for Energy and Power Engineering Majors under the background of carbon peaking.According to the characteristics of teaching and scientific research at present,combined with the characteristics of complexity,interdisciplinary and rapid technology update of this course,this paper discusses the teaching content and teaching design of this course to meet the needs of talents of production,teaching and research under the background of new engineering course.It proposes more applicable teaching methods and practical means to broaden students horizons,stimulate students autonomous learning momentum,master the professional knowledge application ability,and cultivate innovative and competitive engineering professionals to adapt to the new energy strategy.展开更多
In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as th...In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable platform.To implement the micro-supercapacitors in various practical applications that can accompany solid state or gel electrolyte and flexible substrates,ions must be readily transported to electrodes for achieving high power densities.Herein,we show large enhancement in electrochemical properties of flexible,inplane micro-supercapacitor using sharp-edged interdigitated electrode design,which was simply fabricated through direct laser scribing method.The sharp-edged electrodes allowed strong electric field to be induced at the corners of the electrode fingers which led to the greater accumulation of ions near the surface of electrode,significantly enhancing the energy storage performance of micro-supercapacitors.The electric field-enhanced in-plane micro-supercapacitor showed the volumetric energy density of 1.52 Wh L^(−1)and the excellent cyclability with capacitive retention of 95.4%after 20000 cycles.We further showed various practicability of our sharp-edged design in micro-supercapacitors by showing circuit applicability,mechanical stability,and air stability.These results present an important pathway for designing electrodes in various energy storage devices.展开更多
Regulating the local configuration of atomically dispersed transition-metal atom catalysts is the key to oxygen electrocatalysis performance enhancement.Unlike the previously reported singleatom or dual-atom configura...Regulating the local configuration of atomically dispersed transition-metal atom catalysts is the key to oxygen electrocatalysis performance enhancement.Unlike the previously reported singleatom or dual-atom configurations,we designed a new type of binary-atom catalyst,through engineering Fe-N_(4)electronic structure with adjacent Co-N_(2)C_(2)and nitrogen-coordinated Co nanoclusters,as oxygen electrocatalysts.The resultant optimized electronic structure of the Fe-N_(4)active center favors the binding capability of intermediates and enhances oxygen reduction reaction(ORR)activity in both alkaline and acid conditions.In addition,anchoring M-N-C atomic sites on highly graphitized carbon supports guarantees of efficient charge-and mass-transports,and escorts the high bifunctional catalytic activity of the entire catalyst.Further,through the combination of electrochemical studies and in-situ X-ray absorption spectroscopy analyses,the ORR degradation mechanisms under highly oxidative conditions during oxygen evolution reaction processes were revealed.This work developed a new binary-atom catalyst and systematically investigates the effect of highly oxidative environments on ORR electrochemical behavior.It demonstrates the strategy for facilitating oxygen electrocatalytic activity and stability of the atomically dispersed M-N-C catalysts.展开更多
文摘The paper has introduced the Journal 'Advanced Technology of Electrical Engineering and Energy',presented its main journal evaluation indexes. The result indicates that the journal has made great progress in recent years. It gives much info. about the journal to authors.
基金Project supported by the Promising Project Foundation of Zheji-ang University, China
文摘This article describes an Internet based laboratory (NETLAB) developed at Zhejiang University for electrical engi- neering education. A key feature of the project is the use of real experimental systems rather than simulation or virtual reality. NELTAB provides remote access to a wide variety of experiments, including not only basic electrical and electronic experiments but also many innovative control experiments. Students can effectively use the laboratory at any time and from anywhere. NETLAB has been in operation since July 2003.
文摘The paper presented the statistics and analysis on papers published on the journal 'Advanced Technology of Electrical Engineering and Energy' from 1996 to 2008: the paper acceptance rate,the paper category,the first author's affiliations,the top 7 first authors,the top 10 coauthors and also the journal evaluation indexes of the journal.It offers details of the journal to anyone interested,especially to our editorial board and our broad readers.
文摘The paper has introduced the journals on electrical engineering in China in detail, presented its publication year, the distributions for all elec. eng. journals and its core journals, the position and level of the journals, its main journal evaluation indexes, its core journal proportion and inclusion info. by famous international database. The paper offers much information about the journals on electrical engineering in China to readers, and also points out present problems and gives suggestion.
文摘The human brain is asymmetrical in function, with each of its two hemispheres being somewhat responsible for distinct cognitive and motor tasks, to include writing. It stands to reason that engineering students who have established entrance into their upper-division programs will have demonstrated cognitive proficiency in math and logical operations, abstract and analytical reasoning and language usage, to include writing. In this study the question was asked: is there a correlation between an upper-division electrical engineering students’ analytical reasoning ability and their descriptive writing ability? Descriptive writing is taken here to mean a students’ ability to identify key physical aspects of a mathematical model and to express—in words—a concise and well-balanced description that demonstrates a deep conceptual understanding of the model. This includes more than a description of the variables or the particular application to an engineering problem;it includes a demonstrated recognition of the basic physics that govern the model, certain limitations (idealizations) inherent in the model, and an understanding of how to make practical experimental measurements to verify the governing physics in the model. A student at this level may demonstrate proficiency in their analytical reasoning skills and hence be capable of correctly solving a given problem. However, this does not guarantee that the same student is skilled in associating equations with their physical meaning on a deep conceptual level or in understanding physical limitations of the equation. Consequently, such a student may demonstrate difficulty in mapping their comprehension of the model into written language that demonstrates a sound conceptual understanding of the governing physics. The findings represent a sample of two independent class sections of Electrical and Computer Engineering junior’s first course in Microe-lectronic Devices and Circuits during fall semesters 2012 and 2013 at a private mid-size university in NW Oregon. A total of three exams were administered to each of the 2012/2013 groups. Correlations between exam scores that students achieved on their descriptive writing of microelectronics phenomena and their analytical problem-solving abilities were examined and found to be quite significant.
基金supported substantially by the Southwest Jiaotong University for Material and Financial Support。
文摘Graphene(Gr)has unique properties including high electrical conductivity;Thus,graphene/copper(Gr/Cu)composites have attracted increasing attention to replace traditional Cu for electrical applications. However,the problem of how to control graphene to form desired Gr/Cu composite is not well solved. This paper aims at exploring the best parameters for preparing graphene with different layers on Cu foil by chemical vapor deposition(CVD)method and studying the effects of different layers graphene on Gr/Cu composite’s electrical conductivity. Graphene grown on single-sided and double-sided copper was prepared for Gr/Cu and Gr/Cu/Gr composites. The resultant electrical conductivity of Gr/Cu composites increased with decreasing graphene layers and increasing graphene volume fraction. The Gr/Cu/Gr composite with monolayer graphene owns volume fraction of less than 0.002%,producing the best electrical conductivity up to59.8 ×10^(6)S/m,equivalent to 104.5% IACS and 105.3% pure Cu foil.
基金This work was supported by the Anhui Provincial Natural Science Foundation(Grant No.2308085QB69)the Institute of Energy,Hefei Comprehensive National Science Center(Grant No.21KZS210).
文摘Ni-rich layered oxides are potential cathode materials for next-generation high energy density Li-ion batteries due to their high capacity and low cost.However,the inherently unstable surface properties,including high levels of residual Li compounds,dissolution of transition metal cations,and parasitic side reactions,have not been effectively addressed,leading to significant degradation in their electrochemical performance.In this study,we propose a simple and effective lactic acid-assisted interface engineering strategy to regulate the surface chemistry and properties of Ni-rich LiNi_(0.8)Co_(0.1)Mr_(0.1)O_(2) cathode.This novel surface treatment method successfully eliminates surface residual Li compounds,inhibits structural collapse,and mitigates cathode-electrolyte interface film growth.As a result,the lactic acidtreated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) achieved a remarkable capacity retention of 91.7% after 100 cycles at 0.5 C(25℃) and outstanding rate capability of 149.5 mA h g^(-1) at 10 C,significantly outperforming the pristine material.Furthermore,a pouch-type full cell incorporating the modified LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode demonstrates impressive long-term cycle life,retaining 81.5% of its capacity after 500 cycles at 1 C.More importantly,the thermal stability of the modified cathode is also dramatically improved.This study offers a valuable surface modification strategy for enhancing the overall performance of Ni-rich cathode materials.
基金supported in part by the National Key R&D Program of China (No.2021YFB2601404)Beijing Natural Science Foundation (No.3232053)National Natural Science Foundation of China (Nos.51929701 and 52127812)。
文摘In contrast to conventional transformers, power electronic transformers, as an integral component of new energy power system, are often subjected to high-frequency and transient electrical stresses, leading to heightened concerns regarding insulation failures. Meanwhile, the underlying mechanism behind discharge breakdown failure and nanofiller enhancement under high-frequency electrical stress remains unclear. An electric-thermal coupled discharge breakdown phase field model was constructed to study the evolution of the breakdown path in polyimide nanocomposite insulation subjected to high-frequency stress. The investigation focused on analyzing the effect of various factors, including frequency, temperature, and nanofiller shape, on the breakdown path of Polyimide(PI) composites. Additionally, it elucidated the enhancement mechanism of nano-modified composite insulation at the mesoscopic scale. The results indicated that with increasing frequency and temperature, the discharge breakdown path demonstrates accelerated development, accompanied by a gradual dominance of Joule heat energy. This enhancement is attributed to the dispersed electric field distribution and the hindering effect of the nanosheets. The research findings offer a theoretical foundation and methodological framework to inform the optimal design and performance management of new insulating materials utilized in high-frequency power equipment.
基金financially supported by the National Natural Science Foundation of China(52102223,51920105004)。
文摘Antimony(Sb)-ba sed anode materials are feasible candidates for sodium-ion batteries(SIBs) due to their high theoretical specific capacity and excellent electrical conductivity.However,they still suffer from volume distortion,structural collapse,and ionic conduction interruption upon cycling.Herein,a hierarchical array-like nanofiber structure was designed to address these limitations by combining architecture engineering and anion tuning strategy,in which SbPO_(4-x) with oxygen vacancy nanosheet arrays are anchored on the surface of interwoven carbon nanofibers(SbPO_(4-x)@CNFs).In particular,bulky PO_(4)^(3-) anions mitigate the large volume distortion and generate Na_(3)PO_(4) with high ionic conductivity,collectively improving cyclic stability and ionic transport efficiency.The abundant oxygen vacancies substantially boost the intrinsic electronic conductivity of SbPO_4,further accelerating the reaction dynamics.In addition,hierarchical fibrous structures provide abundant active sites,construct efficient conducting networks,and enhance the electron/ion transport capacity.Benefiting from the advanced structural design,the SbPO_(4-x)@CNFs electrodes exhibit outstanding cycling stability(1000 cycles at 1.0 A g^(-1) with capacity decay of 0.05% per cycle) and rapid sodium storage performance(293.8 mA h g^(-1) at 5.0 A g^(-1)).Importantly,systematic in-/ex-situ techniques have revealed the "multi-step conversion-alloying" reaction process and the "battery-capacitor dual-mode" sodium-storage mechanism.This work provides valuable insights into the design of anode materials for advanced SIBs with elevated stability and superior rate performance.
基金Jilin Science and Technology Development Plan Project(No.20200403075SF)Doctoral Research Start-Up Fund of Northeast Electric Power University(No.BSJXM-2018202).
文摘The current existing problem of deep learning framework for the detection and segmentation of electrical equipment is dominantly related to low precision.Because of the reliable,safe and easy-to-operate technology provided by deep learning-based video surveillance for unmanned inspection of electrical equipment,this paper uses the bottleneck attention module(BAM)attention mechanism to improve the Solov2 model and proposes a new electrical equipment segmentation mode.Firstly,the BAM attention mechanism is integrated into the feature extraction network to adaptively learn the correlation between feature channels,thereby improving the expression ability of the feature map;secondly,the weighted sum of CrossEntropy Loss and Dice loss is designed as the mask loss to improve the segmentation accuracy and robustness of the model;finally,the non-maximal suppression(NMS)algorithm to better handle the overlap problem in instance segmentation.Experimental results show that the proposed method achieves an average segmentation accuracy of mAP of 80.4% on three types of electrical equipment datasets,including transformers,insulators and voltage transformers,which improve the detection accuracy by more than 5.7% compared with the original Solov2 model.The segmentation model proposed can provide a focusing technical means for the intelligent management of power systems.
基金supported by grants from City University of Hong Kong,China (Project No.SRG-Fd7005632,SRG-Fd 7005854SIRG 7020058)(to LLHC)。
文摘The connection and interaction between the eye and the brain are crucial to understanding brain disorders(Marchesi et al.,2021).Both the eye and the brain have a limited regenerative capacity as there are few progenitor cells,and nerve cells do not replicate.Hence,neurodegeneration implicates irreversible damage to the central nervous system,as observed in several neurodegenerative diseases(Marchesi et al.,2021).
文摘Under the background of new engineering,the reform of the comprehensive practical course system for mechanical and electronic engineering majors actively responds to the challenges posed by the new round of technological revolution and industrial transformation to higher education,cultivating top-notch innovative intellectuals with comprehensive engineering qualities,meeting the requirements of being able to solve complex engineering problems rather than just cognitive capabilities,forming two core courses through reconstructing and reshaping the core courses of the major.The core courses include Drive,Measurement,and Control I and Drive,Measurement,and Control II,which highlight the comprehensive framework of mechanical and electronic engineering professional knowledge,continuing the comprehensive practical course system based on the unity of knowledge and practice,following the trend of new engineering,highlighting the practicality of professional innovation,assisting engineering education reform,and promoting high-quality development of new engineering professionals cultivation.
基金Supported by the National Science Fundation of China (Grant No.50525721,50595411)the National Basic Research Program of China (Grant No.2004CB217900)
文摘Based on,but not limited to the research results of electrical engineering published in the special issue of Science in China Series E,June 2008,this essay gives a brief review on a wide range of state-of-art advancement in electrical engineering field of China,which includes power system modeling,analysis and control,risk assessments in power system,etc.
基金This research was supported by the Science and Technology Plan Project of Sichuan Province(No.21YYJC3324)the Science and Technology Plan Project of Sichuan Province(No.2022YFQ0104).
文摘A novel three-phase traction power supply system is proposed to eliminate the adverse effects caused by electric phase separation in catenary and accomplish a unifying manner of traction power supply for rail transit.With the application of two-stage three-phase continuous power supply structure,the electrical characteristics exhibit new features differing from the existing traction system.In this work,the principle for voltage levels determining two-stage network is dissected in accordance with the requirements of traction network and electric locomotive.The equivalent model of three-phase traction system is built for deducing the formula of current distribution and voltage losses.Based on the chain network model of the traction network,a simulation model is established to analyze the electrical characteristics such as traction current distribution,voltage losses,system equivalent impedance,voltage distribution,voltage unbalance and regenerative energy utilization.In a few words,quite a lot traction current of about 99%is undertaken by long-section cable network.The proportion of system voltage losses is small attributed to the two-stage three-phase power supply structure,and the voltage unbal-ance caused by impedance asymmetry of traction network is less than 1‰.In addition,the utilization rate of regenerative energy for locomotive achieves a significant promotion of over 97%.
基金supported by the National Key Research and Development Program of China(2023YFE0201600 and 2018YFC1902400)the National Natural Science Foundation of China(51975582)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘Refractory high-entropy alloys(RHEAs)have promising applications as the new generation of hightemperature alloys in hypersonic vehicles,aero-engines,gas turbines,and nuclear power plants.This study focuses on the microstructures and mechanical properties of the NbMoTaW(HfN)_(x)(x=0,0.3,0.7,and 1.0)RHEAs.The alloys consist of multiple phases of body-centered cubic(BCC),hafnium nitride(HfN),or multicomponent nitride(MN)phases.As the x contents increase,the grain size becomes smaller,and the strength gradually increases.The compressive yield strengths of the NbMoTaWHfN RHEA at ambient temperature,1000,1400,and 1800℃ were found to be 1682,1192,792,and 288 MPa,respectively.The high-temperature strength of this alloy is an inspiring result that exceeds the high temperature and strength of most known alloys,including high-entropy alloys,refractory metals,and superalloys.The HfN phase has a significant effect on strengthening due to its high structural stability and sluggish grain coarsening,even at ultra-high temperatures.Its superior properties endow the NbMoTaWHfN RHEA with potential for a wide range of engineering applications at ultra-high temperatures.This work offers a strategy for the design of high-temperature alloys and proposes an ultra-high-temperature alloy with potential for future engineering applications.
文摘The control of dissipation and amplification of solitary waves in an electrical model of a microtubule is demonstrated.This model consists of a shunt nonlinear resistance–capacitance(J(V)–C(V)) circuit and a series resistance–inductance(R–L) circuit. Through linear dispersion analysis, two features of the network are found, that is, low bandpass and bandpass filter characteristics. The effects of the conductance’s parameter λ on the linear dispersion curve are also analyzed. It appears that an increase of λ induces a decrease(an increase) of the width of the bandpass filter for positive(negative) values of λ. By applying the reductive perturbation method, we derive the equation governing the dynamics of the modulated waves in the system. This equation is the well-known nonlinear Schr?dinger equation extended by a linear term proportional to a hybrid parameter σ, i.e., a dissipation or amplification coefficient. Based on this parameter, we successfully demonstrate the hybrid behavior(dissipation and amplification) of the system. The exact and approximate solitary wave solutions of the obtained equation are derived, and the effects of the coefficient σ on the characteristic parameters of these waves are investigated. Using the analytical solutions found, we show numerically that the waves that are propagated throughout the system can be dissipated, amplified, or remain stable depending on the network parameters. These results are not only in agreement with the analytical predictions, but also with the existing experimental results in the literature.
基金Supported by Ideological and Political Teaching Reform Project of Yunnan Agricultural University in 2022(YAUKCSZJG0050)Ideological and Political Teaching Reform Project of Yunnan Agricultural University in 2023(YNAUKCSZJG2023045)First-class Course Construction Project of Yunnan Agricultural University in 2023(2023YLKC019).
文摘The Fundamentals of Combustion course is an important compulsory course for Energy and Power Engineering Majors under the background of carbon peaking.According to the characteristics of teaching and scientific research at present,combined with the characteristics of complexity,interdisciplinary and rapid technology update of this course,this paper discusses the teaching content and teaching design of this course to meet the needs of talents of production,teaching and research under the background of new engineering course.It proposes more applicable teaching methods and practical means to broaden students horizons,stimulate students autonomous learning momentum,master the professional knowledge application ability,and cultivate innovative and competitive engineering professionals to adapt to the new energy strategy.
基金supported by a National Research Foundation of Korea grant funded by the Korean government(MSIT)(2020R1A2C1101039)by Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry,and Energy(MOTIE)of the Republic of Korea(20204030200060)supported by the Soonchunhyang University Research Fund
文摘In plane micro-supercapacitors that are miniaturized energy storage components have attracted significant attention due to their high power densities for various ubiquitous and sustainable device systems as well as their facile integration on various flexible/wearable platform.To implement the micro-supercapacitors in various practical applications that can accompany solid state or gel electrolyte and flexible substrates,ions must be readily transported to electrodes for achieving high power densities.Herein,we show large enhancement in electrochemical properties of flexible,inplane micro-supercapacitor using sharp-edged interdigitated electrode design,which was simply fabricated through direct laser scribing method.The sharp-edged electrodes allowed strong electric field to be induced at the corners of the electrode fingers which led to the greater accumulation of ions near the surface of electrode,significantly enhancing the energy storage performance of micro-supercapacitors.The electric field-enhanced in-plane micro-supercapacitor showed the volumetric energy density of 1.52 Wh L^(−1)and the excellent cyclability with capacitive retention of 95.4%after 20000 cycles.We further showed various practicability of our sharp-edged design in micro-supercapacitors by showing circuit applicability,mechanical stability,and air stability.These results present an important pathway for designing electrodes in various energy storage devices.
基金funded by the National Natural Science Foundation of China (22208331, 52003300)the Natural Sciences and Engineering Research Council of Canada (NSERC)+4 种基金the Fonds de Recherche du Québec-Nature et Technologies (FRQNT)Centre Québécois sur les Materiaux Fonctionnels (CQMF), McGill Universityécole de Technologie Supérieure (éTS)Institut National de la Recherche Scientifique (INRS)the support from the Marcelle-Gauvreau Engineering Research Chair program
文摘Regulating the local configuration of atomically dispersed transition-metal atom catalysts is the key to oxygen electrocatalysis performance enhancement.Unlike the previously reported singleatom or dual-atom configurations,we designed a new type of binary-atom catalyst,through engineering Fe-N_(4)electronic structure with adjacent Co-N_(2)C_(2)and nitrogen-coordinated Co nanoclusters,as oxygen electrocatalysts.The resultant optimized electronic structure of the Fe-N_(4)active center favors the binding capability of intermediates and enhances oxygen reduction reaction(ORR)activity in both alkaline and acid conditions.In addition,anchoring M-N-C atomic sites on highly graphitized carbon supports guarantees of efficient charge-and mass-transports,and escorts the high bifunctional catalytic activity of the entire catalyst.Further,through the combination of electrochemical studies and in-situ X-ray absorption spectroscopy analyses,the ORR degradation mechanisms under highly oxidative conditions during oxygen evolution reaction processes were revealed.This work developed a new binary-atom catalyst and systematically investigates the effect of highly oxidative environments on ORR electrochemical behavior.It demonstrates the strategy for facilitating oxygen electrocatalytic activity and stability of the atomically dispersed M-N-C catalysts.
