The dynamic model of a novel electric power steering （EPS） system integrated with active front steering function （the novel EPS system） is built. The concepts and quantitative expressions of the steering road feel...The dynamic model of a novel electric power steering （EPS） system integrated with active front steering function （the novel EPS system） is built. The concepts and quantitative expressions of the steering road feel, steering sensibility, and steering operation stability are introduced. Based on quality engineering theory, the optimization algorithm is proposed by integrating the Monte Carlo descriptive sampling, elitist non-dominated sorting genetic algorithm （NSGA-II） and 6-sigma design method. With the steering road feel and the steering portability as optimization targets, the system parameters are optimized by the proposed optimization algorithm. The simulation results show that the system optimized based on quality engineering theory can improve the steering road feel, guarantee steering stability and steering portability and thus provide a theoretical basis for the design and optimization of the novel electric power steering system.展开更多
The significance,description parameters,evaluation method,implement way and design for lightweight of automobile are comprehensively reviewed.The relationship among the performances of auto parts & components,the ...The significance,description parameters,evaluation method,implement way and design for lightweight of automobile are comprehensively reviewed.The relationship among the performances of auto parts & components,the properties of materials and application of advanced technologies is also elaborated.According to recently related progress of lightweight and authors' research and developing work,lightweight of automobile is comprehensively and systematically overviewed.展开更多
The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that format...The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that formation cause of surface orange peel after tensile deformation related to product texture and nonuniform deformation during the tensile process.The grain size has significant effect on deformation uniform and texture formation.Coarse grains were easy to produce nonuniform deformation and texture,which would produce surface orange peel after tensile deformation.展开更多
As point cloud of one whole vehicle body has the traits of large geometric dimension,huge data and rigorous reverse precision,one pretreatment algorithm on automobile body point cloud is put forward.The basic idea of ...As point cloud of one whole vehicle body has the traits of large geometric dimension,huge data and rigorous reverse precision,one pretreatment algorithm on automobile body point cloud is put forward.The basic idea of the registration algorithm based on the skeleton points is to construct the skeleton points of the whole vehicle model and the mark points of the separate point cloud,to search the mapped relationship between skeleton points and mark points using congruence triangle method and to match the whole vehicle point cloud using the improved iterative closed point(ICP)algorithm.The data reduction algorithm,based on average square root of distance,condenses data by three steps,computing datasets'average square root of distance in sampling cube grid,sorting order according to the value computed from the first step,choosing sampling percentage.The accuracy of the two algorithms above is proved by a registration and reduction example of whole vehicle point cloud of a certain light truck.展开更多
According to experiments and the phenomena that tailpipes often have dirty particulate matter, this paper takes dynamic theory analysis as its study aim, beginning with the description method of multiphase gas distrib...According to experiments and the phenomena that tailpipes often have dirty particulate matter, this paper takes dynamic theory analysis as its study aim, beginning with the description method of multiphase gas distribution differential equation. According to the characteristics that exhaust gas will flow with high velocity in a tailpipe, it is supposed that gas mass that differ largely will layer when flowing with high velocity in a tailpipe. This means the exhaust gas is mixed with particulate matter, gas with large mass （CO2,HC,NOx） and gas with small mass （CO,H2O,N2,O2）. The interface of two phase fluid will be become clearer as it flows in the pipe for a long distance. The fluid continuous equation between gas phase and solid phase and the mathematical relationship between the geometry parameter and the flowing are established by a multiphase gas flowing theory. Analyzing the interface and state of layers will provide a basic theory for developing a catalytic converter with high efficiency.展开更多
Graphitic carbon nitride(g-C_(3)N_(4)),known for its green and abundant nature and composed of carbon and nitrogen in a two-dimensional structure,has emerged as a significant area of interest across various discipline...Graphitic carbon nitride(g-C_(3)N_(4)),known for its green and abundant nature and composed of carbon and nitrogen in a two-dimensional structure,has emerged as a significant area of interest across various disciplines,particularly in energy conversion and storage.Its recent demonstrations of high potential in supercapacitor applications mark it as a promising alternative to graphene within the realm of materials science.Numerous favorable features,such as chemical and thermal stability,abundant nitrogen content,eco-friendly attributes,and gentle conditions for synthesis,are shown.This review summarizes recent advancements in the use of g-C_(3)N_(4)and its composites as electrodes for supercapacitors,highlighting the advantages and issues associated with g-C_(3)N_(4)in these applications.This emphasizes situations where the composition of g-C_(3)N_(4)with other materials,such as metal oxides,metal chalcogenides,carbon materials,and conducting polymers,overcomes its limitations,leading to composite materials with improved functionalities.This review discusses the challenges that still need to be addressed and the possible future roles of g-C_(3)N_(4)in the research of advanced supercapacitor technology,such as battery-hybrid supercapacitors,flexible supercapacitors,and photo-supercapacitors.展开更多
As a crucial component of intelligent chassis systems,air suspension significantly enhances driver comfort and vehicle stability.To further improve the adaptability of commercial vehicles to complex and variable road ...As a crucial component of intelligent chassis systems,air suspension significantly enhances driver comfort and vehicle stability.To further improve the adaptability of commercial vehicles to complex and variable road conditions,this paper proposes a linear motor active suspension with quasi-zero stiffness(QZS)air spring system.Firstly,a dynamic model of the linear motor active suspension with QZS air spring system is established.Secondly,considering the random uncertainties in the linear motor parameters due to manufacturing and environmental factors,a dynamic model and state equations incorporating these uncertainties are constructed using the polynomial chaos expansion(PCE)method.Then,based on H_(2) robust control theory and the Kalman filter,a state feedback control law is derived,accounting for the random parameter uncertainties.Finally,simulation and hardware-in-the-loop(HIL)experimental results demonstrate that the PCE-H_(2) robust controller not only provides better performance in terms of vehicle ride comfort compared to general H_(2) robust controller but also exhibits higher robustness to the effects of random uncertain parameters,resulting in more stable control performance.展开更多
Whipple shields as sacrificial bumpers,safeguard the satellites against extremely fast,different-sized projectiles traveling through space in the low earth orbit.Typical Whipple shields comprise a front and rear plate...Whipple shields as sacrificial bumpers,safeguard the satellites against extremely fast,different-sized projectiles traveling through space in the low earth orbit.Typical Whipple shields comprise a front and rear plate,separated by a gap or space.Recent advancements have explored the use of foam,cellular cores,and alternative materials such as ceramics instead of aluminium for the plates.In the current work,the effect of including fluid cores(air/water)sandwiched between the front and rear plates,on the response to hypervelocity impact was explored through a numerical approach.The numerical simulation consisted of hypervelocity impact by a 2 mm diameter,stainless steel projectile,launched at speeds of 3 e9 km/s with a normal impact trajectory towards the Whipple shield.The front and rear bumpers,made of AA6061-T6,were each 1 mm thick.A space of 10 mm was taken between the plates(occupied by fluid).The key metrics analyzed were the perforation characteristics,stages of the debris cloud generation and propagation,energy variations(internal,kinetic and plastic work),temperature variations,and the fragmentation summary.From the computational analysis,employing water-core in Whipple shields could prevent the rear bumper perforation till 6 km/s,lower the peak temperatures at the front bumper perforation zones and debris tip,and generate fewer,larger fragments.展开更多
This research investigates the bending response of folded multi-celled tubes(FMTs)fabricated by folded metal sheets.A three-point bending test for FMTs with circular and square sections is designed and introduced.The ...This research investigates the bending response of folded multi-celled tubes(FMTs)fabricated by folded metal sheets.A three-point bending test for FMTs with circular and square sections is designed and introduced.The base numerical models are correlated with physical experiments and a static crashworthiness analysis of six FMT configurations to assess their energy absorption characteristics.The influences of thickness,sectional shape,and load direction on the bending response are studied.Results indicate that increasing the thickness of the tube and radian of the inner tube enhances the crashworthiness performance of FMT,yielding a 20.50%increase in mean crushing force,a 55.53%increase in specific energy absorption,and an 18.05%decrease in peak crushing force compared to traditional multi-celled tubes(TMTs).A theoretical analysis of the specific energy absorption indicates that FMTs outperform TMTs,particularly when the peak crushing force is prominent.This study highlights the innovative and practical potential of FMTs to improve the crashworthiness of thin-walled structures.展开更多
Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic mu...Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic multi-cell double corrugated(BMDC)tube,inspired by Buddha bamboo,is investigated to assess whether it is an ideal energy absorber candidate.Compared to a corrugated tube,a BMDC contains an outer structure,an inner structure,and diaphragms,which are like webs bridging the inner and outer structures.A basic numerical model is correlated using a physical experiment,followed by an investigation of BMDC tubes’energy absorption performance under axial loading,considering thickness and mass effects.Results indicate that the EA,MCF,and SEA of a BMDC containing 5 diaphragms(BMDC-5)with a 1.5 mm thickness can improve their respective responses by 112.89,112.89,and 83.32%higher compared to a BMDC with no diaphragm(BMDC-0).In addition,the BMDC-5 with 0.156 kg mass generates the highest EA,MCF,and SEA,which is 79.78%higher than a BMDC-0 with the same mass.The parametric analysis illustrates that diaphragms’amplitude and diameter have a decisive influence on energy absorption characteristics.This study emphasizes that BMDC tubes are innovative and practical,possessing excellent energy absorption performance.展开更多
The utilization of self-assembled monolayers(SAMs)has significantly elevated the power conversion efficiency(PCE)of inverted perovskite solar cells(PSCs).However,the inherent hydrophobicity of these SAMs poses challen...The utilization of self-assembled monolayers(SAMs)has significantly elevated the power conversion efficiency(PCE)of inverted perovskite solar cells(PSCs).However,the inherent hydrophobicity of these SAMs poses challenges in the subsequent printing of perovskite films in PSC upscaling.In this work,we incorporated a multifunctional additive,dimethyl suberimidate dihydrochloride(DMSCl_(2)),into the perovskite precursor to enhance the quality of the blade-coated perovskite film on the SAM interlayer.Characterizations revealed that the function groups of the imino(N-H)and methoxy(CH_(3)O-)DMSCl_(2) facilitate both bonding between perovskite precursor and SAM molecule(Me-4PACz),which facilitates the large-area printing of perovskite film.These interactions also provide effective passivation within the perovskite films and interface defects of PSCs.As a result,a significantly enhanced PCE from 16.62% to 20.37% was obtained for the printed perovskite solar module(93.10 cm^(2))and 25.27% for the small device(0.09 cm^(2)).Remarkable stability was achieved with 93.3% of their initial PCE after 1000 h of continuous maximum power point(MPP)tracking.This report suggests that multifunctional additive doping provides a convenient route for the upscaling of perovskite solar cells with SAM interlayers.展开更多
Cold Metal Transfer technology has revolutionized the welding of dissimilar metals and thicker materials by producing improved weld bead aesthetics with controlled metal deposition and low heat-input. In this study, t...Cold Metal Transfer technology has revolutionized the welding of dissimilar metals and thicker materials by producing improved weld bead aesthetics with controlled metal deposition and low heat-input. In this study, the process, weld combinations, laser-CMT hybrid welding and applications of CMT welding are critically reviewed. Microstructure and other weld characteristics have been discussed at length for various base metal combinations. Particularly, the welding of aluminium and steel with better results has been possible with CMT Welding. The results reviewed in this article indicate that the CMT-Laser hybrid welding is more preferable to Laser or Laser hybrid welding. CMT welding has found applications in automobile industries, defence sectors and power plants as a method of additive manufacturing.展开更多
Mechanical transmissions are applied widely in various electrical and mechanical products, but some qualities of some high-end products can＇t meet people＇s demand, and need to be improved with some new methods or th...Mechanical transmissions are applied widely in various electrical and mechanical products, but some qualities of some high-end products can＇t meet people＇s demand, and need to be improved with some new methods or theories. The fractal theory is a new mathematic tool, which provides a new approach for the further study in the area of the mechanical transmission, and helps to solve some problems. The basic contents of the fractal theory are introduced firstly, especially the two important concepts, the self-similar fractal and the fractal dimension. Then, the deferent application of the fractal theory in this area are given to display how to further the study and improve some important characteristics of the mechanical transmission, such as contact surfaces, manufacturing precise, friction and wear, stiffness, strength, dynamics, fault diagnosis, etc. Finally, the problems of the fractal theory and its application are discussed, and some weaknesses, such as the calculation capacity of the fractal theory is not strong, are pointed out. Some new solutions are suggested, such as combining the fractal theory with the fuzzy theory, the chaos theory and so on. The new application fields of the fractal theory in the area of the mechanical transmission are proposed.展开更多
The high aerodynamic noise induced by automotive air conditioning systems has important effects on the ride comfort, and the centrifugal fan is the largest noise source in these systems. It is very important to reduce...The high aerodynamic noise induced by automotive air conditioning systems has important effects on the ride comfort, and the centrifugal fan is the largest noise source in these systems. It is very important to reduce the aerodynamic noise generated by the centrifugal fan. The flow field and the sound field on the whole centrifugal fan configuration have been carried out using the computational fluid dynamics. Simulation results show that the sound pressure level near the outlet of the centrifugal fan is too high. Based on the relationship between flow characteristics and the aerodynamic noise, four parameters of the centrifugal fan, i.e., impeller blade＇s outlet angle 0, volute tongue＇s gap t, collector inclination angle fl, and rotating speed n, were selected as design variables and optimized using response surface methodology. While keeping the function of flow rate unchanged, the peak noise level is reduced by 8 dB or 10.8%. The noise level is satisfactorily reduced.展开更多
Friction stir welding between AA5052-H32aluminium plates is performed by central composite design technique of response surface methodology.It is found that the welding parameters such as tool pin profile,tool rotatio...Friction stir welding between AA5052-H32aluminium plates is performed by central composite design technique of response surface methodology.It is found that the welding parameters such as tool pin profile,tool rotational speed,welding speed,and tool tilt angle play a major role in deciding the joint characteristics.The joints fabricated using tapered square pin profile tool with a tool rotational speed of600r/min,welding speed of65mm/min,and tool tilt angle of1.5°result in an unexpected weld efficiency of93.51%.Mathematical models are developed to map the correlation between the parameters and responses(ultimate tensile strength and elongation)and these models are optimized to maximize the ultimate tensile strength of the friction stir welded joint.Response plots generated from the mathematical models are used to interpret the interaction effects of the welding parameters on the response variables.Adequacy of the developed models is validated using analysis of variance(ANOVA)technique.Results from the confirmatory experiments plotted in scatter diagram show a good agreement with predicted models.Different grain structures in various zones of the weld are examined by observing the micro and macro structures of the weld.展开更多
The existing torque roll axis(TRA) decoupling theories for a powertrain mounting system assume that the stiffness and viscous damping properties are constant. However, real-life mounts exhibit considerable spectrally ...The existing torque roll axis(TRA) decoupling theories for a powertrain mounting system assume that the stiffness and viscous damping properties are constant. However, real-life mounts exhibit considerable spectrally varying stiffness and damping characteristics, and the influence of the spectrally-varying properties of the hydraulic mounts on the powertrain system cannot be ignored. To overcome the deficiency, an analytical quasi-linear model of the hydraulic mount and the coupled properties of the powertrain and hydraulic mounts system are formulated. The influence of the hydraulic mounts on the TRA decoupling of a powertrain system is analytically examined in terms of eigensolutions, frequency, and impulse responses, and then a new analytical axiom is proposed based on the TRA decoupling indices. With the experimental setup of a fixed decoupler hydraulic mount in the context of non-resonant dynamic stiffness testing procedure, the quasi-linear model of the hydraulic mount is verified by comparing the predictions with the measurement. And the quasi-linear formulation of the coupled system is also verified by comparing the frequency responses with the numerical results obtained by the direct inversion method. Finally, the mounting system with a combination of hydraulic mounts is redesigned in terms of the stiffness, damping and mount locations by satisfying the new axiom. The frequency and time domain results of the redesigned system demonstrate that the torque roll axis of the redesigned powertrain mounting system is indeed decoupled in the presence of hydraulic mounts (given oscillating torque or impulsive torque excitation). The proposed research provides an important basis and method for the research on a powertrain system with spectrally-varying mount properties, especially for the TRA decoupling.展开更多
Microstructure and texture in 6016 aluminum alloy during hot compression were researched with a uni- axial compression experiment. Through the electron back- scattered diffraction （EBSD） and X-ray diffraction （XRD...Microstructure and texture in 6016 aluminum alloy during hot compression were researched with a uni- axial compression experiment. Through the electron back- scattered diffraction （EBSD） and X-ray diffraction （XRD） analysis technology, it is shown that the subgrain nucle- ation and recrystallization occur in 6016 aluminum alloy during hot compressing, and strong rolling textures such as （110） fiber texture, Brass, S, and Goss form. With the deformation passes increasing, （110） fiber texture, Brass and S are enhanced. In the heat preservation stage after deformation, recrystallization continues until heat preser- vation for 60 s, and a duplex microstructure of deformation and recrystallization grains is built. At the beginning of heat preservation, recrystallization grains with the Goss texture and random orientation are formed in original grains with S or Brass texture, which makes the volume fraction of S and Brass texture decrease. Then, the complex grain growth process makes the volume fraction of Brass, S, and Goss texture increase, while that of random orien- tation decrease.展开更多
In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were d...In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were defined under special conditions.The link travel time model(ice and snowfall based-bureau public road,ISB-BPR) and the path choice decision model(elastic demand user equilibrium,EDUE) were proposed.The integrated reliability was defined and the model was set up.Monte Carlo simulation was used to calculate the model and a numerical example was provided to demonstrate the application of the model and efficiency of the solution algorithm.The results show that the intensity of ice and snowfall,the traffic demand and supply,and the requirements for level of service(LOS) have great influence on the reliability of a road network.For example,the reliability drops from 65% to 5% when the traffic demand increases by 30%.The comprehensive performance index may be used for network planning,design and maintenance.展开更多
In this paper, the two-lane traffic are studied by using the lane-changing rules in the car-following models. The simulation show that the frequent lane changing occurs when the lateral distance in car following activ...In this paper, the two-lane traffic are studied by using the lane-changing rules in the car-following models. The simulation show that the frequent lane changing occurs when the lateral distance in car following activities is considered and it gives rise to oscillating waves. In contrast, if the lateral distance is not considered （or considered occasionally）, the lane changing appears infrequently and soliton waves occurs. This implies that the stabilization mechanism no longer functions when the lane changing is permitted. Since the oscillating and soliton waves correspond to the unstable and metastable flow regimes, respectively, our study verifies that a phase transition may occur as a result of the lane changing.展开更多
基金Projects(51005115,51205191)supported by the National Natural Science Foundation of ChinaProject(QC201101)supported by the Visiting Scholar Foundation of the Automobile Engineering Key Laboratory of Jiangsu Province,China+1 种基金Project(SKLMT-KFKT-201105)supported by the Visiting Scholar Foundation of the State Key Laboratory of Mechanical Transmission in Chongqing University,ChinaProjects(NS2013015,NS2012086)supported by the Funds from the Postgraduate Creative Base in Nanjing University of Areonautics and Astronautics,and NUAA Research Funding,China
文摘The dynamic model of a novel electric power steering （EPS） system integrated with active front steering function （the novel EPS system） is built. The concepts and quantitative expressions of the steering road feel, steering sensibility, and steering operation stability are introduced. Based on quality engineering theory, the optimization algorithm is proposed by integrating the Monte Carlo descriptive sampling, elitist non-dominated sorting genetic algorithm （NSGA-II） and 6-sigma design method. With the steering road feel and the steering portability as optimization targets, the system parameters are optimized by the proposed optimization algorithm. The simulation results show that the system optimized based on quality engineering theory can improve the steering road feel, guarantee steering stability and steering portability and thus provide a theoretical basis for the design and optimization of the novel electric power steering system.
基金International Cooperation Project of Ministry of Science and Technology of China (No.2008DFB50020)
文摘The significance,description parameters,evaluation method,implement way and design for lightweight of automobile are comprehensively reviewed.The relationship among the performances of auto parts & components,the properties of materials and application of advanced technologies is also elaborated.According to recently related progress of lightweight and authors' research and developing work,lightweight of automobile is comprehensively and systematically overviewed.
文摘The formation cause of orange peel of aluminum-alloy automotive sheet after tensile deformation was analysed by using X-ray diffraction and electron back-scattered diffraction(EBSD).The test results showed that formation cause of surface orange peel after tensile deformation related to product texture and nonuniform deformation during the tensile process.The grain size has significant effect on deformation uniform and texture formation.Coarse grains were easy to produce nonuniform deformation and texture,which would produce surface orange peel after tensile deformation.
基金This project is supported by Provincial Technology Cooperation Program of Yunnan,China(No.2003EAAAA00D043).
文摘As point cloud of one whole vehicle body has the traits of large geometric dimension,huge data and rigorous reverse precision,one pretreatment algorithm on automobile body point cloud is put forward.The basic idea of the registration algorithm based on the skeleton points is to construct the skeleton points of the whole vehicle model and the mark points of the separate point cloud,to search the mapped relationship between skeleton points and mark points using congruence triangle method and to match the whole vehicle point cloud using the improved iterative closed point(ICP)algorithm.The data reduction algorithm,based on average square root of distance,condenses data by three steps,computing datasets'average square root of distance in sampling cube grid,sorting order according to the value computed from the first step,choosing sampling percentage.The accuracy of the two algorithms above is proved by a registration and reduction example of whole vehicle point cloud of a certain light truck.
文摘According to experiments and the phenomena that tailpipes often have dirty particulate matter, this paper takes dynamic theory analysis as its study aim, beginning with the description method of multiphase gas distribution differential equation. According to the characteristics that exhaust gas will flow with high velocity in a tailpipe, it is supposed that gas mass that differ largely will layer when flowing with high velocity in a tailpipe. This means the exhaust gas is mixed with particulate matter, gas with large mass （CO2,HC,NOx） and gas with small mass （CO,H2O,N2,O2）. The interface of two phase fluid will be become clearer as it flows in the pipe for a long distance. The fluid continuous equation between gas phase and solid phase and the mathematical relationship between the geometry parameter and the flowing are established by a multiphase gas flowing theory. Analyzing the interface and state of layers will provide a basic theory for developing a catalytic converter with high efficiency.
基金financial support of the TMA pai scholarship from the Manipal Institute of Technology,Manipal Academy of Higher Education,Manipal,in achieving this milestone。
文摘Graphitic carbon nitride(g-C_(3)N_(4)),known for its green and abundant nature and composed of carbon and nitrogen in a two-dimensional structure,has emerged as a significant area of interest across various disciplines,particularly in energy conversion and storage.Its recent demonstrations of high potential in supercapacitor applications mark it as a promising alternative to graphene within the realm of materials science.Numerous favorable features,such as chemical and thermal stability,abundant nitrogen content,eco-friendly attributes,and gentle conditions for synthesis,are shown.This review summarizes recent advancements in the use of g-C_(3)N_(4)and its composites as electrodes for supercapacitors,highlighting the advantages and issues associated with g-C_(3)N_(4)in these applications.This emphasizes situations where the composition of g-C_(3)N_(4)with other materials,such as metal oxides,metal chalcogenides,carbon materials,and conducting polymers,overcomes its limitations,leading to composite materials with improved functionalities.This review discusses the challenges that still need to be addressed and the possible future roles of g-C_(3)N_(4)in the research of advanced supercapacitor technology,such as battery-hybrid supercapacitors,flexible supercapacitors,and photo-supercapacitors.
基金Supported by National Natural Science Foundation of China(Grant No.51875256)Open Platform Fund of Human Institute of Technology(Grant No.KFA22009).
文摘As a crucial component of intelligent chassis systems,air suspension significantly enhances driver comfort and vehicle stability.To further improve the adaptability of commercial vehicles to complex and variable road conditions,this paper proposes a linear motor active suspension with quasi-zero stiffness(QZS)air spring system.Firstly,a dynamic model of the linear motor active suspension with QZS air spring system is established.Secondly,considering the random uncertainties in the linear motor parameters due to manufacturing and environmental factors,a dynamic model and state equations incorporating these uncertainties are constructed using the polynomial chaos expansion(PCE)method.Then,based on H_(2) robust control theory and the Kalman filter,a state feedback control law is derived,accounting for the random parameter uncertainties.Finally,simulation and hardware-in-the-loop(HIL)experimental results demonstrate that the PCE-H_(2) robust controller not only provides better performance in terms of vehicle ride comfort compared to general H_(2) robust controller but also exhibits higher robustness to the effects of random uncertain parameters,resulting in more stable control performance.
文摘Whipple shields as sacrificial bumpers,safeguard the satellites against extremely fast,different-sized projectiles traveling through space in the low earth orbit.Typical Whipple shields comprise a front and rear plate,separated by a gap or space.Recent advancements have explored the use of foam,cellular cores,and alternative materials such as ceramics instead of aluminium for the plates.In the current work,the effect of including fluid cores(air/water)sandwiched between the front and rear plates,on the response to hypervelocity impact was explored through a numerical approach.The numerical simulation consisted of hypervelocity impact by a 2 mm diameter,stainless steel projectile,launched at speeds of 3 e9 km/s with a normal impact trajectory towards the Whipple shield.The front and rear bumpers,made of AA6061-T6,were each 1 mm thick.A space of 10 mm was taken between the plates(occupied by fluid).The key metrics analyzed were the perforation characteristics,stages of the debris cloud generation and propagation,energy variations(internal,kinetic and plastic work),temperature variations,and the fragmentation summary.From the computational analysis,employing water-core in Whipple shields could prevent the rear bumper perforation till 6 km/s,lower the peak temperatures at the front bumper perforation zones and debris tip,and generate fewer,larger fragments.
基金supported by the National Natural Science Foundation of China(Grant No.52475277)2022 Guangxi University Young and Middle-aged Teachers’Basic Research Ability Improvement Project(Grant No.2022KY0781)Scientific Research Funds of Guilin University of Aerospace Technology(Grant No.XJ22KT29).
文摘This research investigates the bending response of folded multi-celled tubes(FMTs)fabricated by folded metal sheets.A three-point bending test for FMTs with circular and square sections is designed and introduced.The base numerical models are correlated with physical experiments and a static crashworthiness analysis of six FMT configurations to assess their energy absorption characteristics.The influences of thickness,sectional shape,and load direction on the bending response are studied.Results indicate that increasing the thickness of the tube and radian of the inner tube enhances the crashworthiness performance of FMT,yielding a 20.50%increase in mean crushing force,a 55.53%increase in specific energy absorption,and an 18.05%decrease in peak crushing force compared to traditional multi-celled tubes(TMTs).A theoretical analysis of the specific energy absorption indicates that FMTs outperform TMTs,particularly when the peak crushing force is prominent.This study highlights the innovative and practical potential of FMTs to improve the crashworthiness of thin-walled structures.
基金2022 Guangxi University Young and Middle-aged Teachers’Basic Research Ability Improvement Project,2022KY0781,Rui Liang。
文摘Multi-cell structures and corrugated tubes illustrate excellent energy absorption capacities.Besides,bamboo with continuously changing contours demonstrates superior impact-resisting capacities.As a result,a bionic multi-cell double corrugated(BMDC)tube,inspired by Buddha bamboo,is investigated to assess whether it is an ideal energy absorber candidate.Compared to a corrugated tube,a BMDC contains an outer structure,an inner structure,and diaphragms,which are like webs bridging the inner and outer structures.A basic numerical model is correlated using a physical experiment,followed by an investigation of BMDC tubes’energy absorption performance under axial loading,considering thickness and mass effects.Results indicate that the EA,MCF,and SEA of a BMDC containing 5 diaphragms(BMDC-5)with a 1.5 mm thickness can improve their respective responses by 112.89,112.89,and 83.32%higher compared to a BMDC with no diaphragm(BMDC-0).In addition,the BMDC-5 with 0.156 kg mass generates the highest EA,MCF,and SEA,which is 79.78%higher than a BMDC-0 with the same mass.The parametric analysis illustrates that diaphragms’amplitude and diameter have a decisive influence on energy absorption characteristics.This study emphasizes that BMDC tubes are innovative and practical,possessing excellent energy absorption performance.
基金financially supported by the Guangdong Pearl River Talent Program(2021ZT09L400)the National Natural Science Foundation of China(52302195,52072284)+1 种基金the Joint Funds of Natural Science Foundation of Hubei Province(2022CFD087)the Scientific Research and Technology Development Project of China National Petroleum Corporation(Grant Nos.2024ZG50)。
文摘The utilization of self-assembled monolayers(SAMs)has significantly elevated the power conversion efficiency(PCE)of inverted perovskite solar cells(PSCs).However,the inherent hydrophobicity of these SAMs poses challenges in the subsequent printing of perovskite films in PSC upscaling.In this work,we incorporated a multifunctional additive,dimethyl suberimidate dihydrochloride(DMSCl_(2)),into the perovskite precursor to enhance the quality of the blade-coated perovskite film on the SAM interlayer.Characterizations revealed that the function groups of the imino(N-H)and methoxy(CH_(3)O-)DMSCl_(2) facilitate both bonding between perovskite precursor and SAM molecule(Me-4PACz),which facilitates the large-area printing of perovskite film.These interactions also provide effective passivation within the perovskite films and interface defects of PSCs.As a result,a significantly enhanced PCE from 16.62% to 20.37% was obtained for the printed perovskite solar module(93.10 cm^(2))and 25.27% for the small device(0.09 cm^(2)).Remarkable stability was achieved with 93.3% of their initial PCE after 1000 h of continuous maximum power point(MPP)tracking.This report suggests that multifunctional additive doping provides a convenient route for the upscaling of perovskite solar cells with SAM interlayers.
文摘Cold Metal Transfer technology has revolutionized the welding of dissimilar metals and thicker materials by producing improved weld bead aesthetics with controlled metal deposition and low heat-input. In this study, the process, weld combinations, laser-CMT hybrid welding and applications of CMT welding are critically reviewed. Microstructure and other weld characteristics have been discussed at length for various base metal combinations. Particularly, the welding of aluminium and steel with better results has been possible with CMT Welding. The results reviewed in this article indicate that the CMT-Laser hybrid welding is more preferable to Laser or Laser hybrid welding. CMT welding has found applications in automobile industries, defence sectors and power plants as a method of additive manufacturing.
基金Supported by International Co-operation Program of China(Grant No.2014DFA80440)
文摘Mechanical transmissions are applied widely in various electrical and mechanical products, but some qualities of some high-end products can＇t meet people＇s demand, and need to be improved with some new methods or theories. The fractal theory is a new mathematic tool, which provides a new approach for the further study in the area of the mechanical transmission, and helps to solve some problems. The basic contents of the fractal theory are introduced firstly, especially the two important concepts, the self-similar fractal and the fractal dimension. Then, the deferent application of the fractal theory in this area are given to display how to further the study and improve some important characteristics of the mechanical transmission, such as contact surfaces, manufacturing precise, friction and wear, stiffness, strength, dynamics, fault diagnosis, etc. Finally, the problems of the fractal theory and its application are discussed, and some weaknesses, such as the calculation capacity of the fractal theory is not strong, are pointed out. Some new solutions are suggested, such as combining the fractal theory with the fuzzy theory, the chaos theory and so on. The new application fields of the fractal theory in the area of the mechanical transmission are proposed.
基金Project(50975083) supported by the National Natural Science Foundation of ChinaProject(61075001) supported by China State Key Laboratory of Advanced Design and Manufacturing for Vehicle BodyProject(201-IV-068) supported by the Fundamental Research Funds for the Central Universities,China
文摘The high aerodynamic noise induced by automotive air conditioning systems has important effects on the ride comfort, and the centrifugal fan is the largest noise source in these systems. It is very important to reduce the aerodynamic noise generated by the centrifugal fan. The flow field and the sound field on the whole centrifugal fan configuration have been carried out using the computational fluid dynamics. Simulation results show that the sound pressure level near the outlet of the centrifugal fan is too high. Based on the relationship between flow characteristics and the aerodynamic noise, four parameters of the centrifugal fan, i.e., impeller blade＇s outlet angle 0, volute tongue＇s gap t, collector inclination angle fl, and rotating speed n, were selected as design variables and optimized using response surface methodology. While keeping the function of flow rate unchanged, the peak noise level is reduced by 8 dB or 10.8%. The noise level is satisfactorily reduced.
文摘Friction stir welding between AA5052-H32aluminium plates is performed by central composite design technique of response surface methodology.It is found that the welding parameters such as tool pin profile,tool rotational speed,welding speed,and tool tilt angle play a major role in deciding the joint characteristics.The joints fabricated using tapered square pin profile tool with a tool rotational speed of600r/min,welding speed of65mm/min,and tool tilt angle of1.5°result in an unexpected weld efficiency of93.51%.Mathematical models are developed to map the correlation between the parameters and responses(ultimate tensile strength and elongation)and these models are optimized to maximize the ultimate tensile strength of the friction stir welded joint.Response plots generated from the mathematical models are used to interpret the interaction effects of the welding parameters on the response variables.Adequacy of the developed models is validated using analysis of variance(ANOVA)technique.Results from the confirmatory experiments plotted in scatter diagram show a good agreement with predicted models.Different grain structures in various zones of the weld are examined by observing the micro and macro structures of the weld.
基金supported by National Natural Science Foundation of China (Grant Nos. 51075112, 51175135)Fundamental Research Funds for the Central Universities of China (Grant Nos. 2012HGBZ0618,2013HGBH0008)
文摘The existing torque roll axis(TRA) decoupling theories for a powertrain mounting system assume that the stiffness and viscous damping properties are constant. However, real-life mounts exhibit considerable spectrally varying stiffness and damping characteristics, and the influence of the spectrally-varying properties of the hydraulic mounts on the powertrain system cannot be ignored. To overcome the deficiency, an analytical quasi-linear model of the hydraulic mount and the coupled properties of the powertrain and hydraulic mounts system are formulated. The influence of the hydraulic mounts on the TRA decoupling of a powertrain system is analytically examined in terms of eigensolutions, frequency, and impulse responses, and then a new analytical axiom is proposed based on the TRA decoupling indices. With the experimental setup of a fixed decoupler hydraulic mount in the context of non-resonant dynamic stiffness testing procedure, the quasi-linear model of the hydraulic mount is verified by comparing the predictions with the measurement. And the quasi-linear formulation of the coupled system is also verified by comparing the frequency responses with the numerical results obtained by the direct inversion method. Finally, the mounting system with a combination of hydraulic mounts is redesigned in terms of the stiffness, damping and mount locations by satisfying the new axiom. The frequency and time domain results of the redesigned system demonstrate that the torque roll axis of the redesigned powertrain mounting system is indeed decoupled in the presence of hydraulic mounts (given oscillating torque or impulsive torque excitation). The proposed research provides an important basis and method for the research on a powertrain system with spectrally-varying mount properties, especially for the TRA decoupling.
基金financially supported by the Original Program of Chongqing Foundational and Frontier Research Plan(No.cstc2013jcyjA70015)the Science and Technology Research Program of Education Council of Chongqing(No.KJ080407)
文摘Microstructure and texture in 6016 aluminum alloy during hot compression were researched with a uni- axial compression experiment. Through the electron back- scattered diffraction （EBSD） and X-ray diffraction （XRD） analysis technology, it is shown that the subgrain nucle- ation and recrystallization occur in 6016 aluminum alloy during hot compressing, and strong rolling textures such as （110） fiber texture, Brass, S, and Goss form. With the deformation passes increasing, （110） fiber texture, Brass and S are enhanced. In the heat preservation stage after deformation, recrystallization continues until heat preser- vation for 60 s, and a duplex microstructure of deformation and recrystallization grains is built. At the beginning of heat preservation, recrystallization grains with the Goss texture and random orientation are formed in original grains with S or Brass texture, which makes the volume fraction of S and Brass texture decrease. Then, the complex grain growth process makes the volume fraction of Brass, S, and Goss texture increase, while that of random orien- tation decrease.
基金Project(E200940) supported by the Natural Science Foundation of Heilongjiang Province, ChinaProject(2009GC20008020) supported by the Technology Research and Development Program of Shandong Province, China
文摘In order to evaluate and integrate travel time reliability and capacity reliability of a road network subjected to ice and snowfall conditions,the conceptions of travel time reliability and capacity reliability were defined under special conditions.The link travel time model(ice and snowfall based-bureau public road,ISB-BPR) and the path choice decision model(elastic demand user equilibrium,EDUE) were proposed.The integrated reliability was defined and the model was set up.Monte Carlo simulation was used to calculate the model and a numerical example was provided to demonstrate the application of the model and efficiency of the solution algorithm.The results show that the intensity of ice and snowfall,the traffic demand and supply,and the requirements for level of service(LOS) have great influence on the reliability of a road network.For example,the reliability drops from 65% to 5% when the traffic demand increases by 30%.The comprehensive performance index may be used for network planning,design and maintenance.
基金The project supported by the National Natural Science Foundation of China （70521001, 10404025, 10532060）the National Basic Research Program of China （2006CB705503） the Research Grants Council of the Hong Kong Special Administrative Region （HKU7031/02E, HKU7187/05E）.
文摘In this paper, the two-lane traffic are studied by using the lane-changing rules in the car-following models. The simulation show that the frequent lane changing occurs when the lateral distance in car following activities is considered and it gives rise to oscillating waves. In contrast, if the lateral distance is not considered （or considered occasionally）, the lane changing appears infrequently and soliton waves occurs. This implies that the stabilization mechanism no longer functions when the lane changing is permitted. Since the oscillating and soliton waves correspond to the unstable and metastable flow regimes, respectively, our study verifies that a phase transition may occur as a result of the lane changing.
