With the rapid development of electronic information engineering,high-speed digital circuits have been increasingly widely applied in various fields.In high-speed digital circuits,signal integrity is prone to interfer...With the rapid development of electronic information engineering,high-speed digital circuits have been increasingly widely applied in various fields.In high-speed digital circuits,signal integrity is prone to interference from various external factors,leading to issues such as signal distortion or degradation of system performance.Based on this,this paper conducts research on the optimization strategies for signal integrity of high-speed digital circuits in electronic information engineering.It deeply analyzes the importance of high-speed digital circuits,elaborates on the challenges they face and the specific manifestations of signal integrity issues,and proposes a series of optimization strategies in electronic information engineering.The aim is to improve the signal integrity of highspeed digital circuits and provide theoretical support and practical guidance for the development of related fields.展开更多
Feature extraction in the optical domain offers a promising low-latency,high-throughput solution.Optical diffraction-based feature extraction operating under a coherent light source can further achieve parallel output...Feature extraction in the optical domain offers a promising low-latency,high-throughput solution.Optical diffraction-based feature extraction operating under a coherent light source can further achieve parallel outputs with low energy consumption.However,it presents significant challenges for maintaining the coherent input,scaling the operation rates beyond 10 GHz,and ensuring the effective extraction of functional configuration simultaneously.We propose an optical feature extraction engine(OFE^(2)),which is composed of a diffraction operator and a data preparation module,powering high-speed feature extraction for both image and temporal series tasks.This OFE^(2)can achieve a core latency of less than 250.5 ps;in addition,it can reach a throughput of 250 GOPS and an efficiency of 2.06 TOPS/W.Supported by the OFE^(2),a novel feature extraction paradigm is emerging,enabling high-speed,low-latency service access for applications in scene recognition,medical assistance,and digital finance.展开更多
A growing global population and the increasing prevalence of diet-related health issues such as“hidden hunger”,obesity,hypertension,and diabetes necessitate a fundamental rethinking of crop design and breeding.Synth...A growing global population and the increasing prevalence of diet-related health issues such as“hidden hunger”,obesity,hypertension,and diabetes necessitate a fundamental rethinking of crop design and breeding.Synthetic metabolic engineering offers a method to modify and redesign metabolic pathways to increase the nutritional value of crops.We summarize recent advances in the biofortification of key nutrients including provitamin A,vitamin C,vitamin B9,iron,zinc,anthocyanins,flavonoids,and unsaturated fatty acids.We discuss the potential of multi-gene stacking,gene editing,enzyme engineering,and artificial intelligence in synthetic metabolic engineering.We propose future research directions and potential solutions centered on leveraging AI-driven systems biology,precision gene editing,enzyme engineering,agrobacterium-mediated genotype-independent transformation,and modular metabolic engineering strategies to develop next-generation nutritionally enhanced super crops and transform global food systems.展开更多
A CAD system for the cylinder head is developed. As an integrated system, it can be used in 3 D modeling, 2 D drawing and finite element structural analysis and optimization. The key problems in system designing are...A CAD system for the cylinder head is developed. As an integrated system, it can be used in 3 D modeling, 2 D drawing and finite element structural analysis and optimization. The key problems in system designing are introduced. Design flow, system structure and how to solve the key problems are focused on. All of those would form the base for more research on how to use the modern CAD technology to design complex engine parts. And it is also a good example of using the modern CAD technology.展开更多
This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and...This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and the stress and aerodynamic load measurement points are reasonably arranged accordingly.The actual measurement is carried out in combination with the operating conditions of the existing lines.The stress variations and spectral characteristics of the train under different speed levels(80,160,180,200 km/h),tunnel entry and exit,and scraper action conditions were compared and analyzed.The stress amplification factors under tunnel intersection and scraper action were obtained,providing boundary conditions for the design of wipers for highspeed s.The research results show that the maximum stress of the wiper structure obtained through simulation calculation is concentrated at the connection of the wiper arm.Structural stress increases with the rise of speed grade.The stress increases by 1.11 times when the tunnel meets.When the scraper operates,the stress on the scraper arm increases by 4.1–7.6 times.Due to the broadband excitation effect of the aerodynamic load,the spectral energy of the structure is relatively high at the natural frequency,which excites the natural mode of the wiper.展开更多
This paper proposes a passive control method to reduce peak values of slipstream and turbulent kinetic energy in a high-speed train wake by attaching vortex generators(VGs)onto the upper surface of the tail car.The im...This paper proposes a passive control method to reduce peak values of slipstream and turbulent kinetic energy in a high-speed train wake by attaching vortex generators(VGs)onto the upper surface of the tail car.The impact of the VGs is assessed through the improved delayed detached eddy simulations(IDDES)after validating predictions against previous experimental measurements and other numerical predictions for the base case.The simulations indicate that strategically installed VGs can reduce the average slipstream velocity(U slipstream)and the upper limit of slipstream velocity(U_(slipstream,max))by~17%and~15%,respectively,as well as moving the peaks downstream by approximately train height,thus reducing the danger posed by slipstream to waiting passengers and trackside workers.Analysis shows that the wake turbulent kinetic energy diminishes as the vortex generators decelerate the downwash flow and reduce shear production in the wake.It is also found that the presence of VGs significantly impacts the flow on the upper surface near the tail by modifying the unsteady trailing longitudinal vortices through the formation of additional counter-rotating longitudinal vortices from the VGs.These latter vortices prevent the merging of vortical airflow around the trailing nose tip,which is otherwise induced by the longitudinal vortex of the train.They also reduce vortex intensity through cross-annihilation and cross diffusion as the wake advects downstream,limiting outwards advection through interaction with the image pair,and contributing to a decrease in the peak slipstream value.The method proposed offers a simple approach to wake control leading to significant slipstream benefits.展开更多
The axle box bearings of high-speed trains often operate in extremely harsh environments,bearing loads from different directions.Long-term operation and frequent changes in working conditions can easily lead to axle b...The axle box bearings of high-speed trains often operate in extremely harsh environments,bearing loads from different directions.Long-term operation and frequent changes in working conditions can easily lead to axle box bearing failures.Therefore,it is extremely important to study the mechanism of axle box bearings.Firstly,the medium of thermal deformation establishes a coupling relationship between the system dynamics model and the thermal grid model,and then obtains the thermal force coupling model of the high-speed train axle box bearing.The coupling model is validated from the perspectives of system dynamics response and temperature response,proving its effectiveness in system dynamics response and temperature characteristic response.Comparing the coupling model with the dynamics model,it is found that thermal deformation complicates the dynamic re-sponse.Finally,using the Lundberg-Palmgren(L-P)bearing fatigue calculation method and damage accumu-lation theory,the bearing fatigue life is calculated,and it is found that thermal deformation deteriorates the bearing operating environment,reducing the bearing fatigue life.Finally,by comparing the bearing fatigue life under different working conditions,it is concluded that the faster the vehicle speed,the greater the load,and the smaller the initial radial clearance of the bearing,the fatigue life of the bearing is reduced.The shorter the lifespan.展开更多
Research on high-speed railways is a relatively new yet highly significant field in Vietnam.Among its key components,train control signaling plays a critical role,as it directly affects various interconnected systems,...Research on high-speed railways is a relatively new yet highly significant field in Vietnam.Among its key components,train control signaling plays a critical role,as it directly affects various interconnected systems,including infrastructure,traction power supply,operational planning,and overall railway safety.This article focuses on evaluating the capacity of the line based on the types of signals suitable for high-speed railways that have been effectively implemented in several European countries and successfully adapted in China.The research and simulation are conducted using MATLAB software,a reliable and widely adopted tool in the scientific community.The findings demonstrate that under normal conditions,the European Railway Traffic Management System/European Train Control System(ERTMS/ETCS)Level 2 signaling can support up to 23.7485 trains/hour/direction.Meanwhile,ERTMS/ETCS Level 3 with full moving block can accommodate up to 30.8735 trains/hour/direction,and ERTMS/ETCS Level 3 with fixed virtual blocks up to 29.4694 trains/hour/direction.In emergency scenarios,ERTMS/ETCS Level 3 with full moving block reduces headway by 33.27%compared to CTCS Level 3,while ERTMS/ETCS Level 3 with fixed virtual blocks achieves a 28.78%reduction.Overall,the ERTMS/ETCS Level 3 emerges as a state-of-the-art signaling technology offering high capacity and operational efficiency,and is recommended as a forward-looking solution for future implementation in Vietnam.展开更多
As China's high-speed railway technology advances,high-speed trains have emerged as a pivotal mode of transportation,instrumental in facilitating passenger and freight mobility while fostering robust regional eco-...As China's high-speed railway technology advances,high-speed trains have emerged as a pivotal mode of transportation,instrumental in facilitating passenger and freight mobility while fostering robust regional eco-nomic and trade interactions.Nonetheless,the safety of train operations remains a paramount concern,prompting extensive research into the dynamic behavior of critical components,which is essential to ensuring seamless and secure transportation services.This article commences by comprehensively reviewing the current landscape and evolutionary trajectory of dynamic model analysis for both traditional bearings and axle box bearings.Emphasis is placed on elucidating the profound influence of diverse bearing fault types on the system's kinematic state,alongside delving into the research methodologies employed in developing multi-physics field coupling models.Subsequently,it expounds on the content of investigations focusing on various wheel and track impairments,grounded in the dynamic modeling of the bearing vehicle coupling system.Concurrently,the intricate interplay between wheel-rail excitation and axle box bearing faults on the system's performance is elucidated.Concludingly,the article underscores the inadequacy of current multi-source fault diagnosis meth-odologies in tackling the intricacies of complex train operating environments,thereby highlighting its sig-nificance as a pressing and vital research agenda for the future.展开更多
The spatial offset of bridge has a significant impact on the safety,comfort,and durability of high-speed railway(HSR)operations,so it is crucial to rapidly and effectively detect the spatial offset of operational HSR ...The spatial offset of bridge has a significant impact on the safety,comfort,and durability of high-speed railway(HSR)operations,so it is crucial to rapidly and effectively detect the spatial offset of operational HSR bridges.Drive-by monitoring of bridge uneven settlement demonstrates significant potential due to its practicality,cost-effectiveness,and efficiency.However,existing drive-by methods for detecting bridge offset have limitations such as reliance on a single data source,low detection accuracy,and the inability to identify lateral deformations of bridges.This paper proposes a novel drive-by inspection method for spatial offset of HSR bridge based on multi-source data fusion of comprehensive inspection train.Firstly,dung beetle optimizer-variational mode decomposition was employed to achieve adaptive decomposition of non-stationary dynamic signals,and explore the hidden temporal relationships in the data.Subsequently,a long short-term memory neural network was developed to achieve feature fusion of multi-source signal and accurate prediction of spatial settlement of HSR bridge.A dataset of track irregularities and CRH380A high-speed train responses was generated using a 3D train-track-bridge interaction model,and the accuracy and effectiveness of the proposed hybrid deep learning model were numerically validated.Finally,the reliability of the proposed drive-by inspection method was further validated by analyzing the actual measurement data obtained from comprehensive inspection train.The research findings indicate that the proposed approach enables rapid and accurate detection of spatial offset in HSR bridge,ensuring the long-term operational safety of HSR bridges.展开更多
Lacto-N-neotetraose(LNn T)is a crucial neutral core human milk oligosaccharide(HMO).In this study,we established a LNn T-producing Saccharomyces cerevisiae cell factory through comprehensive metabolic engineering.Spec...Lacto-N-neotetraose(LNn T)is a crucial neutral core human milk oligosaccharide(HMO).In this study,we established a LNn T-producing Saccharomyces cerevisiae cell factory through comprehensive metabolic engineering.Specifically,the de novo biosynthetic pathway of LNn T was assembled by heterologously expressing the lactose permease(lac12)from Kluyveromyces lactis and the glycosyltransferase from Neisseria meningitidis in S.cerevisiae.Subsequently,carbon source regulation based on the glucose-sensitive GAL regulatory system was employed to optimize the expression time of heterologous genes,achieving a production of 15.61 mg/L of LNn T in shake-flask fermentation.In addition,the key rate-limiting steps involved in LNn T synthesis pathway were identified and the corresponding genes were overexpressed to enhance LNn T production,resulting in an 8-fold increase in LNn T titer compared to that of parental strain.To our knowledge,this is the first report on LNn T biosynthesis in S.cerevisiae,opening up the possibility of green production of LNn T using food-safe microorganisms.展开更多
Electrocatalytic nitric oxide(NO)reduction reaction(NORR)is a promising and sustainable process that can simultaneously realize green ammonia(NH3)synthesis and hazardous NO removal.However,current NORR performances ar...Electrocatalytic nitric oxide(NO)reduction reaction(NORR)is a promising and sustainable process that can simultaneously realize green ammonia(NH3)synthesis and hazardous NO removal.However,current NORR performances are far from practical needs due to the lack of efficient electrocatalysts.Engineering the lattice of metal-based nanomaterials via phase control has emerged as an effective strategy to modulate their intrinsic electrocatalytic properties.Herein,we realize boron(B)-insertion-induced phase regulation of rhodium(Rh)nanocrystals to obtain amorphous Rh_(4)B nanoparticles(NPs)and hexagonal close-packed(hcp)RhB NPs through a facile wet-chemical method.A high Faradaic efficiency(92.1±1.2%)and NH_(3) yield rate(629.5±11.0μmol h^(−1) cm^(−2))are achieved over hcp RhB NPs,far superior to those of most reported NORR nanocatalysts.In situ spectro-electrochemical analysis and density functional theory simulations reveal that the excellent electrocatalytic performances of hcp RhB NPs are attributed to the upshift of d-band center,enhanced NO adsorption/activation profile,and greatly reduced energy barrier of the rate-determining step.A demonstrative Zn-NO battery is assembled using hcp RhB NPs as the cathode and delivers a peak power density of 4.33 mW cm−2,realizing simultaneous NO removal,NH3 synthesis,and electricity output.展开更多
Railway noise barriers are an essential piece of infrastructure for reducing noise propagation.However,these barriers experience aerodynamic loads generated by high-speed trains,leading to dynamic effects that may com...Railway noise barriers are an essential piece of infrastructure for reducing noise propagation.However,these barriers experience aerodynamic loads generated by high-speed trains,leading to dynamic effects that may compromise their fatigue capacity.The most common structural design for railway noise barriers consists of vertical configurations of posts and panels.However,there have been few dynamic analyses of steel post/wood panel noise barriers under train-induced aerodynamic loads.This study used dynamic finite element analysis to assess the dynamic behavior of such noise barriers.Analysis of a 40-m-long noise barrier model and a triangular simplified load model,the latter of which effectively represented the detailed aerodynamic load,were first used to establish the model and input of the moving load during dynamic simulation.Then,the effects of different parameters on the dynamic response of the noise barrier were evaluated,including the damping ratio,the profile of the steel post,the span length of the panel,the barrier height,and the train speed.Gray relational analysis indicated that barrier height exhibited the highest correlations with the dynamic responses,followed by train speed,post profile,span length,and damping ratio.A reduction in the natural frequency and an increase in the train speed result in a higher peak response and more pronounced fluctuations between the nose and tail waves.The dynamic amplification factor(DAF)was found to be related to both the natural frequency and train speed.A model was proposed showing that the DAF significantly increases as the square of the natural frequency decreases and the cube of the train speed rises.展开更多
With the advent of the AI era,how can students effectively utilize generative AI large models to assist in course learning?At the same time,how can teachers utilize generative AI tools and the teaching concept of OBE ...With the advent of the AI era,how can students effectively utilize generative AI large models to assist in course learning?At the same time,how can teachers utilize generative AI tools and the teaching concept of OBE to stimulate students’innovative consciousness and teamwork ability,enabling students to identify some problems in a certain industry or field and creatively propose feasible solutions,and truly achieve the cultivation of new models in software engineering course teaching with the assistance of generative AI tools?This paper presents research and practice on a new model for cultivating software engineering courses that integrates generative AI and OBE,introduces the specific process of teaching reform and practice,and finally explains the achievements of teaching reform.展开更多
All-inorganic lead-free perovskite solar cells have emerged as environmentally benign candidates;however,their device performance is still constrained by pronounced carrier recombination losses in the bulk and at inte...All-inorganic lead-free perovskite solar cells have emerged as environmentally benign candidates;however,their device performance is still constrained by pronounced carrier recombination losses in the bulk and at interfaces.By combining energy band alignment analysis with detailed modeling of recombination mechanisms,a systematic strategy for optimizing hole transport layers is developed.The results reveal that a negative valence band offset produces a cliff-like interface,which facilitates hole extraction while also accounting for the observed variations in open-circuit voltage.Furthermore,short-circuit current losses are quantitatively attributed to different recombination pathways,modeled by incorporating radiative,Shockley–Read–Hall,Auger,and interface recombination processes.This comprehensive approach not only clarifies the correlation between energy level alignment and recombination dynamics but also highlights the competing roles of band offset and interface defects in determining device performance.The optimized device architecture,based on Ge-based lead-free perovskites,achieves a power conversion efficiency of 25.1%,with an open-circuit voltage of 1.29 V,a short-circuit current density of 22.5 mA·cm^(-2),and a fill factor of 86.3%.These findings provide theoretical guidance for designing stable,high-performance,and environmentally friendly lead-free perovskite solar cells.展开更多
High-performance alloys are indispensable in modern engineering because of their exceptional strength,ductility,corrosion resistance,fatigue resistance,and thermal stability,which are all significantly influenced by t...High-performance alloys are indispensable in modern engineering because of their exceptional strength,ductility,corrosion resistance,fatigue resistance,and thermal stability,which are all significantly influenced by the alloy interface structures.Despite substantial efforts,a comprehensive overview of interface engineering of high-performance alloys has not been presented so far.In this study,the interfaces in high-performance alloys,particularly grain and phase boundaries,were systematically examined,with emphasis on their crystallographic characteristics and chemical element segregations.The effects of the interfaces on the electrical conductivity,mechanical strength,toughness,hydrogen embrittlement resistance,and thermal stability of the alloys were elucidated.Moreover,correlations among various types of interfaces and advanced experimental and computational techniques were examined using big data analytics,enabling robust design strategies.Challenges currently faced in the field of interface engineering and emerging opportunities in the field are also discussed.The study results would guide the development of next-generation high-performance alloys.展开更多
Aqueous zinc(Zn)metal batteries(AZMBs)have distinct advantages in terms of safety and cost-effectiveness.However,the industrial application of AZMBs is currently not ready due to challenges of Zn dendrite growth and t...Aqueous zinc(Zn)metal batteries(AZMBs)have distinct advantages in terms of safety and cost-effectiveness.However,the industrial application of AZMBs is currently not ready due to challenges of Zn dendrite growth and the side reactions such as hydrogen evolution reaction(HER)on the Zn anodes.In this review,we discuss how inorganic interfaces impact the Zn^(2+)plating/stripping reaction and overall cell performance.The discussion is categorized based on the types of inorganic materials,including metal oxides,other metal compounds,and inorganic salts.The proposed protection mechanisms for Zn metal anodes are highlighted,with a focus on the dendrite and HER inhibition mechanisms facilitated by various inorganic materials.We also provide our perspective on the rational design of advanced interfaces to enable highly reversible Zn^(2+)plating/stripping reactions toward highly stable AZMBs,paving the way for their practical implementation in energy storage.展开更多
文摘With the rapid development of electronic information engineering,high-speed digital circuits have been increasingly widely applied in various fields.In high-speed digital circuits,signal integrity is prone to interference from various external factors,leading to issues such as signal distortion or degradation of system performance.Based on this,this paper conducts research on the optimization strategies for signal integrity of high-speed digital circuits in electronic information engineering.It deeply analyzes the importance of high-speed digital circuits,elaborates on the challenges they face and the specific manifestations of signal integrity issues,and proposes a series of optimization strategies in electronic information engineering.The aim is to improve the signal integrity of highspeed digital circuits and provide theoretical support and practical guidance for the development of related fields.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFE0203600)the National Natural Science Foundation of China(Grant No.62135009).
文摘Feature extraction in the optical domain offers a promising low-latency,high-throughput solution.Optical diffraction-based feature extraction operating under a coherent light source can further achieve parallel outputs with low energy consumption.However,it presents significant challenges for maintaining the coherent input,scaling the operation rates beyond 10 GHz,and ensuring the effective extraction of functional configuration simultaneously.We propose an optical feature extraction engine(OFE^(2)),which is composed of a diffraction operator and a data preparation module,powering high-speed feature extraction for both image and temporal series tasks.This OFE^(2)can achieve a core latency of less than 250.5 ps;in addition,it can reach a throughput of 250 GOPS and an efficiency of 2.06 TOPS/W.Supported by the OFE^(2),a novel feature extraction paradigm is emerging,enabling high-speed,low-latency service access for applications in scene recognition,medical assistance,and digital finance.
基金supported by grants from the Guangxi Science and Technology Major Project(GKAA24206023)the Biological Breeding-National Science and Technology Major Project(2024ZD04077)+2 种基金the National Natural Science Foundation of China(32272120)the National Key Research and Development Program of China(2024YFF1000800)the Guangdong Basic Research Center of Excellence for Precise Breeding of Future Crops Major Project(FCBRCE-202502,FCBRCE-202504).
文摘A growing global population and the increasing prevalence of diet-related health issues such as“hidden hunger”,obesity,hypertension,and diabetes necessitate a fundamental rethinking of crop design and breeding.Synthetic metabolic engineering offers a method to modify and redesign metabolic pathways to increase the nutritional value of crops.We summarize recent advances in the biofortification of key nutrients including provitamin A,vitamin C,vitamin B9,iron,zinc,anthocyanins,flavonoids,and unsaturated fatty acids.We discuss the potential of multi-gene stacking,gene editing,enzyme engineering,and artificial intelligence in synthetic metabolic engineering.We propose future research directions and potential solutions centered on leveraging AI-driven systems biology,precision gene editing,enzyme engineering,agrobacterium-mediated genotype-independent transformation,and modular metabolic engineering strategies to develop next-generation nutritionally enhanced super crops and transform global food systems.
文摘A CAD system for the cylinder head is developed. As an integrated system, it can be used in 3 D modeling, 2 D drawing and finite element structural analysis and optimization. The key problems in system designing are introduced. Design flow, system structure and how to solve the key problems are focused on. All of those would form the base for more research on how to use the modern CAD technology to design complex engine parts. And it is also a good example of using the modern CAD technology.
文摘This paper studies the structural response of high-speed train wipers under the combined action of complex flow fields and scraping actions.The stress concentration areas are determined through simulation analysis,and the stress and aerodynamic load measurement points are reasonably arranged accordingly.The actual measurement is carried out in combination with the operating conditions of the existing lines.The stress variations and spectral characteristics of the train under different speed levels(80,160,180,200 km/h),tunnel entry and exit,and scraper action conditions were compared and analyzed.The stress amplification factors under tunnel intersection and scraper action were obtained,providing boundary conditions for the design of wipers for highspeed s.The research results show that the maximum stress of the wiper structure obtained through simulation calculation is concentrated at the connection of the wiper arm.Structural stress increases with the rise of speed grade.The stress increases by 1.11 times when the tunnel meets.When the scraper operates,the stress on the scraper arm increases by 4.1–7.6 times.Due to the broadband excitation effect of the aerodynamic load,the spectral energy of the structure is relatively high at the natural frequency,which excites the natural mode of the wiper.
基金Project(52372370)supported by the National Natural Science Foundation of ChinaProject(2023ZZTS0379)supported by the Graduate Student Independent Innovation Project of Central South University,ChinaProject(202206370058)supported by the China Scholarship Council。
文摘This paper proposes a passive control method to reduce peak values of slipstream and turbulent kinetic energy in a high-speed train wake by attaching vortex generators(VGs)onto the upper surface of the tail car.The impact of the VGs is assessed through the improved delayed detached eddy simulations(IDDES)after validating predictions against previous experimental measurements and other numerical predictions for the base case.The simulations indicate that strategically installed VGs can reduce the average slipstream velocity(U slipstream)and the upper limit of slipstream velocity(U_(slipstream,max))by~17%and~15%,respectively,as well as moving the peaks downstream by approximately train height,thus reducing the danger posed by slipstream to waiting passengers and trackside workers.Analysis shows that the wake turbulent kinetic energy diminishes as the vortex generators decelerate the downwash flow and reduce shear production in the wake.It is also found that the presence of VGs significantly impacts the flow on the upper surface near the tail by modifying the unsteady trailing longitudinal vortices through the formation of additional counter-rotating longitudinal vortices from the VGs.These latter vortices prevent the merging of vortical airflow around the trailing nose tip,which is otherwise induced by the longitudinal vortex of the train.They also reduce vortex intensity through cross-annihilation and cross diffusion as the wake advects downstream,limiting outwards advection through interaction with the image pair,and contributing to a decrease in the peak slipstream value.The method proposed offers a simple approach to wake control leading to significant slipstream benefits.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12393780,12032017,12302067)College Education Scientific Research Project of Hebei Province(Grant No.JZX2024006)Hebei Provincial S&T Program(Grant No.21567622 H).
文摘The axle box bearings of high-speed trains often operate in extremely harsh environments,bearing loads from different directions.Long-term operation and frequent changes in working conditions can easily lead to axle box bearing failures.Therefore,it is extremely important to study the mechanism of axle box bearings.Firstly,the medium of thermal deformation establishes a coupling relationship between the system dynamics model and the thermal grid model,and then obtains the thermal force coupling model of the high-speed train axle box bearing.The coupling model is validated from the perspectives of system dynamics response and temperature response,proving its effectiveness in system dynamics response and temperature characteristic response.Comparing the coupling model with the dynamics model,it is found that thermal deformation complicates the dynamic re-sponse.Finally,using the Lundberg-Palmgren(L-P)bearing fatigue calculation method and damage accumu-lation theory,the bearing fatigue life is calculated,and it is found that thermal deformation deteriorates the bearing operating environment,reducing the bearing fatigue life.Finally,by comparing the bearing fatigue life under different working conditions,it is concluded that the faster the vehicle speed,the greater the load,and the smaller the initial radial clearance of the bearing,the fatigue life of the bearing is reduced.The shorter the lifespan.
文摘Research on high-speed railways is a relatively new yet highly significant field in Vietnam.Among its key components,train control signaling plays a critical role,as it directly affects various interconnected systems,including infrastructure,traction power supply,operational planning,and overall railway safety.This article focuses on evaluating the capacity of the line based on the types of signals suitable for high-speed railways that have been effectively implemented in several European countries and successfully adapted in China.The research and simulation are conducted using MATLAB software,a reliable and widely adopted tool in the scientific community.The findings demonstrate that under normal conditions,the European Railway Traffic Management System/European Train Control System(ERTMS/ETCS)Level 2 signaling can support up to 23.7485 trains/hour/direction.Meanwhile,ERTMS/ETCS Level 3 with full moving block can accommodate up to 30.8735 trains/hour/direction,and ERTMS/ETCS Level 3 with fixed virtual blocks up to 29.4694 trains/hour/direction.In emergency scenarios,ERTMS/ETCS Level 3 with full moving block reduces headway by 33.27%compared to CTCS Level 3,while ERTMS/ETCS Level 3 with fixed virtual blocks achieves a 28.78%reduction.Overall,the ERTMS/ETCS Level 3 emerges as a state-of-the-art signaling technology offering high capacity and operational efficiency,and is recommended as a forward-looking solution for future implementation in Vietnam.
基金Supported by the National Natural Science Foundation of China(Grant Nos.12393783,12302067,12172235,52072249)Joint Funds of the National Natural Science Foundation of China(Grant No.U24A2003)+3 种基金College Education Scientific Research Project of Hebei Province(Grant No.JZX2024006)Central Guiding Local Scientific and Technological Development Funding Project(Grant No.246Z2206G)the Key Research Project of China State Railway Group Co.,Ltd.(Grant No.N2024T009)S&T Program of Hebei(Grant No.21567622H).
文摘As China's high-speed railway technology advances,high-speed trains have emerged as a pivotal mode of transportation,instrumental in facilitating passenger and freight mobility while fostering robust regional eco-nomic and trade interactions.Nonetheless,the safety of train operations remains a paramount concern,prompting extensive research into the dynamic behavior of critical components,which is essential to ensuring seamless and secure transportation services.This article commences by comprehensively reviewing the current landscape and evolutionary trajectory of dynamic model analysis for both traditional bearings and axle box bearings.Emphasis is placed on elucidating the profound influence of diverse bearing fault types on the system's kinematic state,alongside delving into the research methodologies employed in developing multi-physics field coupling models.Subsequently,it expounds on the content of investigations focusing on various wheel and track impairments,grounded in the dynamic modeling of the bearing vehicle coupling system.Concurrently,the intricate interplay between wheel-rail excitation and axle box bearing faults on the system's performance is elucidated.Concludingly,the article underscores the inadequacy of current multi-source fault diagnosis meth-odologies in tackling the intricacies of complex train operating environments,thereby highlighting its sig-nificance as a pressing and vital research agenda for the future.
基金sponsored by the National Natural Science Foundation of China(Grant No.52178100).
文摘The spatial offset of bridge has a significant impact on the safety,comfort,and durability of high-speed railway(HSR)operations,so it is crucial to rapidly and effectively detect the spatial offset of operational HSR bridges.Drive-by monitoring of bridge uneven settlement demonstrates significant potential due to its practicality,cost-effectiveness,and efficiency.However,existing drive-by methods for detecting bridge offset have limitations such as reliance on a single data source,low detection accuracy,and the inability to identify lateral deformations of bridges.This paper proposes a novel drive-by inspection method for spatial offset of HSR bridge based on multi-source data fusion of comprehensive inspection train.Firstly,dung beetle optimizer-variational mode decomposition was employed to achieve adaptive decomposition of non-stationary dynamic signals,and explore the hidden temporal relationships in the data.Subsequently,a long short-term memory neural network was developed to achieve feature fusion of multi-source signal and accurate prediction of spatial settlement of HSR bridge.A dataset of track irregularities and CRH380A high-speed train responses was generated using a 3D train-track-bridge interaction model,and the accuracy and effectiveness of the proposed hybrid deep learning model were numerically validated.Finally,the reliability of the proposed drive-by inspection method was further validated by analyzing the actual measurement data obtained from comprehensive inspection train.The research findings indicate that the proposed approach enables rapid and accurate detection of spatial offset in HSR bridge,ensuring the long-term operational safety of HSR bridges.
基金funded by the National Key Research and Development Program of China(2022YFF1100300)National Natural Science Foundation of China(22108097)+2 种基金Key Research and Development Program of Jiangsu Province(BE2022850)Taihu Innovation-Leading Talent of Wuxi City(1026010241230040)Cross-Integration Innovation Funding of SFST(SFST2023-KY-10).
文摘Lacto-N-neotetraose(LNn T)is a crucial neutral core human milk oligosaccharide(HMO).In this study,we established a LNn T-producing Saccharomyces cerevisiae cell factory through comprehensive metabolic engineering.Specifically,the de novo biosynthetic pathway of LNn T was assembled by heterologously expressing the lactose permease(lac12)from Kluyveromyces lactis and the glycosyltransferase from Neisseria meningitidis in S.cerevisiae.Subsequently,carbon source regulation based on the glucose-sensitive GAL regulatory system was employed to optimize the expression time of heterologous genes,achieving a production of 15.61 mg/L of LNn T in shake-flask fermentation.In addition,the key rate-limiting steps involved in LNn T synthesis pathway were identified and the corresponding genes were overexpressed to enhance LNn T production,resulting in an 8-fold increase in LNn T titer compared to that of parental strain.To our knowledge,this is the first report on LNn T biosynthesis in S.cerevisiae,opening up the possibility of green production of LNn T using food-safe microorganisms.
基金funding support from General Research Fund[Project No.14300525]from the Research Grants Council(RGC)of Hong Kong SAR,Chinafunding support from Natural Science Foundation of China(NSFC)Young Scientists Fund(Project No.22305203)+2 种基金NSFC Projects Nos.22309123,22422303,22303011,22033002,92261112 and U21A20328support from the Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM)at City University of Hong Kongsupport from Young Collaborative Research Grant[Project No.C1003-23Y]support from RGC of Hong Kong SAR,China.
文摘Electrocatalytic nitric oxide(NO)reduction reaction(NORR)is a promising and sustainable process that can simultaneously realize green ammonia(NH3)synthesis and hazardous NO removal.However,current NORR performances are far from practical needs due to the lack of efficient electrocatalysts.Engineering the lattice of metal-based nanomaterials via phase control has emerged as an effective strategy to modulate their intrinsic electrocatalytic properties.Herein,we realize boron(B)-insertion-induced phase regulation of rhodium(Rh)nanocrystals to obtain amorphous Rh_(4)B nanoparticles(NPs)and hexagonal close-packed(hcp)RhB NPs through a facile wet-chemical method.A high Faradaic efficiency(92.1±1.2%)and NH_(3) yield rate(629.5±11.0μmol h^(−1) cm^(−2))are achieved over hcp RhB NPs,far superior to those of most reported NORR nanocatalysts.In situ spectro-electrochemical analysis and density functional theory simulations reveal that the excellent electrocatalytic performances of hcp RhB NPs are attributed to the upshift of d-band center,enhanced NO adsorption/activation profile,and greatly reduced energy barrier of the rate-determining step.A demonstrative Zn-NO battery is assembled using hcp RhB NPs as the cathode and delivers a peak power density of 4.33 mW cm−2,realizing simultaneous NO removal,NH3 synthesis,and electricity output.
基金financially supported by the Swedish Transport Administration(Trafikverket)through the“Excellence Area 4”and FOI-BBT program(Grant Nos.BBT-2019-022 and BBT-TRV 2024/132497).
文摘Railway noise barriers are an essential piece of infrastructure for reducing noise propagation.However,these barriers experience aerodynamic loads generated by high-speed trains,leading to dynamic effects that may compromise their fatigue capacity.The most common structural design for railway noise barriers consists of vertical configurations of posts and panels.However,there have been few dynamic analyses of steel post/wood panel noise barriers under train-induced aerodynamic loads.This study used dynamic finite element analysis to assess the dynamic behavior of such noise barriers.Analysis of a 40-m-long noise barrier model and a triangular simplified load model,the latter of which effectively represented the detailed aerodynamic load,were first used to establish the model and input of the moving load during dynamic simulation.Then,the effects of different parameters on the dynamic response of the noise barrier were evaluated,including the damping ratio,the profile of the steel post,the span length of the panel,the barrier height,and the train speed.Gray relational analysis indicated that barrier height exhibited the highest correlations with the dynamic responses,followed by train speed,post profile,span length,and damping ratio.A reduction in the natural frequency and an increase in the train speed result in a higher peak response and more pronounced fluctuations between the nose and tail waves.The dynamic amplification factor(DAF)was found to be related to both the natural frequency and train speed.A model was proposed showing that the DAF significantly increases as the square of the natural frequency decreases and the cube of the train speed rises.
基金supported by the Shanghai Municipal Education Research Project“Exploring the Practical Application of Generative Artificial Intelligence in Cultivating Innovative Thinking and Capabilities of Interdisciplinary Application Technology Talents‘Practice Path’”(C2025299)the university-level postgraduate course project“Software Process Management”(PX-2025251502)of Shanghai Sanda Universitythe key course project at the university level of Shanghai Sanda University,“Introduction to Software Engineering”(PX-5241216).
文摘With the advent of the AI era,how can students effectively utilize generative AI large models to assist in course learning?At the same time,how can teachers utilize generative AI tools and the teaching concept of OBE to stimulate students’innovative consciousness and teamwork ability,enabling students to identify some problems in a certain industry or field and creatively propose feasible solutions,and truly achieve the cultivation of new models in software engineering course teaching with the assistance of generative AI tools?This paper presents research and practice on a new model for cultivating software engineering courses that integrates generative AI and OBE,introduces the specific process of teaching reform and practice,and finally explains the achievements of teaching reform.
基金supported by the National Natural Science Foundation of China(Grant Nos.52102165 and 62474056)the Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant Nos.NY221029 and NY222165)。
文摘All-inorganic lead-free perovskite solar cells have emerged as environmentally benign candidates;however,their device performance is still constrained by pronounced carrier recombination losses in the bulk and at interfaces.By combining energy band alignment analysis with detailed modeling of recombination mechanisms,a systematic strategy for optimizing hole transport layers is developed.The results reveal that a negative valence band offset produces a cliff-like interface,which facilitates hole extraction while also accounting for the observed variations in open-circuit voltage.Furthermore,short-circuit current losses are quantitatively attributed to different recombination pathways,modeled by incorporating radiative,Shockley–Read–Hall,Auger,and interface recombination processes.This comprehensive approach not only clarifies the correlation between energy level alignment and recombination dynamics but also highlights the competing roles of band offset and interface defects in determining device performance.The optimized device architecture,based on Ge-based lead-free perovskites,achieves a power conversion efficiency of 25.1%,with an open-circuit voltage of 1.29 V,a short-circuit current density of 22.5 mA·cm^(-2),and a fill factor of 86.3%.These findings provide theoretical guidance for designing stable,high-performance,and environmentally friendly lead-free perovskite solar cells.
基金supported by the National Natural Science Foundation of China(Nos.52122408 and 52474397)the High-level Talent Research Start-up Project Funding of Henan Academy of Sciences(No.242017127)+1 种基金the financial support from the Fundamental Research Funds for the Central Universities(University of Science and Technology Beijing(USTB),Nos.FRF-TP-2021-04C1 and 06500135)supported by USTB MatCom of Beijing Advanced Innovation Center for Materials Genome Engineering。
文摘High-performance alloys are indispensable in modern engineering because of their exceptional strength,ductility,corrosion resistance,fatigue resistance,and thermal stability,which are all significantly influenced by the alloy interface structures.Despite substantial efforts,a comprehensive overview of interface engineering of high-performance alloys has not been presented so far.In this study,the interfaces in high-performance alloys,particularly grain and phase boundaries,were systematically examined,with emphasis on their crystallographic characteristics and chemical element segregations.The effects of the interfaces on the electrical conductivity,mechanical strength,toughness,hydrogen embrittlement resistance,and thermal stability of the alloys were elucidated.Moreover,correlations among various types of interfaces and advanced experimental and computational techniques were examined using big data analytics,enabling robust design strategies.Challenges currently faced in the field of interface engineering and emerging opportunities in the field are also discussed.The study results would guide the development of next-generation high-performance alloys.
基金supported by the National Natural Science Foundation of China(52272183)the Fundamental Research Funds for the Central Universities(buctrc202316)the support of the China Experience Fund and the Stephen Slavens Faculty Scholar Endowment Fund from Oregon State University。
文摘Aqueous zinc(Zn)metal batteries(AZMBs)have distinct advantages in terms of safety and cost-effectiveness.However,the industrial application of AZMBs is currently not ready due to challenges of Zn dendrite growth and the side reactions such as hydrogen evolution reaction(HER)on the Zn anodes.In this review,we discuss how inorganic interfaces impact the Zn^(2+)plating/stripping reaction and overall cell performance.The discussion is categorized based on the types of inorganic materials,including metal oxides,other metal compounds,and inorganic salts.The proposed protection mechanisms for Zn metal anodes are highlighted,with a focus on the dendrite and HER inhibition mechanisms facilitated by various inorganic materials.We also provide our perspective on the rational design of advanced interfaces to enable highly reversible Zn^(2+)plating/stripping reactions toward highly stable AZMBs,paving the way for their practical implementation in energy storage.
