Intelligent connected vehicles(ICVs) are believed to change people's life in the near future by making the transportation safer,cleaner and more comfortable. Although many prototypes of ICVs have been developed to...Intelligent connected vehicles(ICVs) are believed to change people's life in the near future by making the transportation safer,cleaner and more comfortable. Although many prototypes of ICVs have been developed to prove the concept of autonomous driving and the feasibility of improving traffic efficiency, there still exists a significant gap before achieving mass production of high-level ICVs. The objective of this study is to present an overview of both the state of the art and future perspectives of key technologies that are needed for future ICVs. It is a challenging task to review all related works and predict their future perspectives, especially for such a complex and interdisciplinary area of research. This article is organized to overview the ICV key technologies by answering three questions: what are the milestones in the history of ICVs; what are the electronic components needed for building an ICV platform; and what are the essential algorithms to enable intelligent driving? To answer the first question, the article has reviewed the history and the development milestones of ICVs. For the second question, the recent technology advances in electrical/electronic architecture, sensors, and actuators are presented. For the third question, the article focuses on the algorithms in decision making, as the perception and control algorithm are covered in the development of sensors and actuators. To achieve correct decision-making, there exist two different approaches: the principle-based approach and data-driven approach. The advantages and limitations of both approaches are explained and analyzed. Currently automotive engineers are concerned more with the vehicle platform technology, whereas the academic researchers prefer to focus on theoretical algorithms. However, only by incorporating elements from both worlds can we accelerate the production of high-level ICVs.展开更多
A novel electric power steering system(EPS) integrated with active front steering(AFS) is developed.It has functions of both AFS system and EPS system with two actuator units:the AFS actuator unit and the EPS actuator...A novel electric power steering system(EPS) integrated with active front steering(AFS) is developed.It has functions of both AFS system and EPS system with two actuator units:the AFS actuator unit and the EPS actuator unit.The AFS actuator unit controls the displacement transfer behavior of the steering system,and improves the handling stability under adverse road conditions by varying the steering ratio directly related to the speed and road conditions.The EPS actuator unit controls the force transfer behavior of the steering system,and improves the steering portability and road feel of the vehicle.Based on a dynamic model,the mixed H2/H∞ control strategy of the EPS actuator and the active steering intervention control strategy of the AFS actuator are designed.The simulation indicates that the novel EPS system with the designed control strategies has obvious advantages in vehicle handling stability and the driver's road feel over the traditional EPS system,and extends the vehicle's steering performance.展开更多
The lateral control for lane changing of intelligent vehicle on curved road in automatic highway systems was studied. Based on trapezoidal acceleration profile, considering the curvature difference between starting la...The lateral control for lane changing of intelligent vehicle on curved road in automatic highway systems was studied. Based on trapezoidal acceleration profile, considering the curvature difference between starting lane and target lane, a new virtual trajectory planning method for lane changing on curved road was presented, and the calculating formulas for ideal states of vehicle in the inertial coordinate system during a lane changing maneuver were established. Applying the predetermined trajectory, the reference yaw angle and yaw rate for lane changing were generated. On the assumption that the information on yaw rate of vehicle can be measured with on-board sensors and based on the lateral dynamical model of vehicle, the yaw-rate-tracking control law was designed by applying nonsingular terminal sliding mode technology. Based on Lyapunov function method, the finite-time convergence property of the system was obtained from the phase-plane analysis. Simulation results showed that if the curvature difference between starting lane and target lane was not considered, then at the finishing time of lane changing, it was impossible to avoid the deviation of the virtual trajectory panned from the target lane, which increased with the decrease of curvature radius. With the trajectory planning method and yaw rate-tracking control law proposed in this paper and considering the curvature difference between the starting lane and target lane, the desired virtual trajectory for lane changing without deviation was obtained and the expected tracking performance was also verified by the simulation.展开更多
Magnesium is one of the largely available elements in the earth’s crust. It has a low structural density with high specific strength. This unique material property has forced an increase in the use of magnesium and i...Magnesium is one of the largely available elements in the earth’s crust. It has a low structural density with high specific strength. This unique material property has forced an increase in the use of magnesium and its alloys in various applications pertaining to industrial sector,automobiles, aerospace and biomedical. Since magnesium is a highly reactive metal, it is prone to higher rate of corrosion as compared to its counterparts. Thus, it is essential to analyze the corrosion behavior of magnesium and its alloys in its applications. An appropriate process is to be followed in the design and development of magnesium alloys which overcome the limitations of magnesium and enhance the desired material properties in accordance to their applications. This review paper summarizes the importance of magnesium and its material properties. The influence of various alloying elements on the mechanical properties of magnesium is reviewed. The broad classification of Mg alloys and their behavioral trends are detailed. The corrosion behavior of magnesium and the influence of corrosion products on the material characteristics of magnesium, in aqueous medium, are discussed. The manufacturing techniques of magnesium alloys along with the secondary techniques are also covered. The various applications and the limitations of magnesium in these applications are covered. A complete section is dedicated towards detailing the recent trends of magnesium(Mg) alloys, i.e., the biodegradable nature and applications of Mg alloys. The influence of biocorrosion on Mg alloys and techniques to overcome it have been deliberated. This paper provides a thorough review on recent developments of magnesium with respect to engineering applications.展开更多
In this work, a scalable and cost-effective method including mechanical milling, centrifugation and spray drying was developed to fabricate Si nanoparticles.The synthesized Si nanoparticles show an average size of 62 ...In this work, a scalable and cost-effective method including mechanical milling, centrifugation and spray drying was developed to fabricate Si nanoparticles.The synthesized Si nanoparticles show an average size of 62 nm and exhibit a narrow particle size distribution. The influence of particle sizes on electrochemical performance of Si-based electrode was investigated, and it is found that as the particle size decreases in the studied range, the Si particles show a lower specific capacity and a higher irreversible capacity loss(ICL). Furthermore, an oxide layer with thickness of ～3 nm was detected on the surface of the as-received Si nanoparticles, and this layer can be effectively removed by hydrofluoric acid(HF) etching,resulting in much improved electrochemical performance over the as-received samples.展开更多
On-road emission and fuel consumption （FC） levels for Euro Ⅲ and Ⅳ buses fueled on diesel and compressed natural gas （CNG） were compared, and emission and FC characteristics of buses were analyzed based on appro...On-road emission and fuel consumption （FC） levels for Euro Ⅲ and Ⅳ buses fueled on diesel and compressed natural gas （CNG） were compared, and emission and FC characteristics of buses were analyzed based on approximately 28,700 groups of instantaneous data obtained in Beijing using a portable emissions measurement system （PEMS）. The experimental results revealed that NOx and PM emissions from CNG buses were decreased by 72.0% and 82.3% respectively, compared with Euro IV diesel buses. Similarly, these emissions were reduced by 75.2% and 96.3% respectively, compared with Euro III diesel buses. In addition, CO2, CO, HC, NOx, PM emissions and FC of Euro IV diesel buses were reduced by 26.4%, 75.2%, 73.6%, 11.4%, 79.1%, and 26.0%, respectively, relative to Euro Ⅲ diesel buses. The CO2, CO, HC, NOx, PM emissions and FC factors all decreased with bus speed increased, while increased as bus acceleration increased. At the same time, the emission/FC rates as well as the emission/FC factors exhibited a strong positive correlation with the vehicle specific power （VSP）. They all were the lowest when VSP 〈 0, and then rapidly increased as VSP increased. Furthermore, both the emission/FC rates and emission/FC factors were the highest at accelerations, higher at cruise speeds, and the lowest at decelerations for non-idling buses. These results can provide a base reference to further estimate bus emission and FC inventories in Beijing.展开更多
In this paper,overcharge behaviors and thermal runaway(TR)features of large format lithium-ion(Liion)cells with different cathode materials(LiFePO4(LFP),Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2)(NCM111),Li[Ni_(0.6)Co_(0.2)Mn_...In this paper,overcharge behaviors and thermal runaway(TR)features of large format lithium-ion(Liion)cells with different cathode materials(LiFePO4(LFP),Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2)(NCM111),Li[Ni_(0.6)Co_(0.2)Mn_(0.2)]O_(2)(NCM622)and Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM811))were investigated.The results showed that,under the same overcharge condition,the TR of LFP Li-ion cell occurred earlier compared with the NCM Li-ion cells,indicating its poor overcharge tolerance and high TR risk.However,when TR occurred,LFP Li-ion cell exhibited lower maximum temperature and mild TR response.All NCM Liion cells caught fire or exploded during TR,while the LFP Li-ion cell only released a large amount of smoke without fire.According to the overcharge behaviors and TR features,a safety assessment score system was proposed to evaluate the safety of the cells.In short,NCM Li-ion cells have better performance in energy density and overcharge tolerance(or low TR risk),while LFP Li-ion cell showed less severe response to overcharging(or less TR hazards).For NCM Li-ion cells,as the ratio of nickel in cathode material increases,the thermal stability of the cathode materials becomes poorer,and the TR hazards increase.Such a comparison study on large format Li-ion cells with different cathode materials can provide deeper insights into the overcharge behaviors and TR features,and provide guidance for engineers to reasonably choose battery materials in automotive applications.展开更多
As a complex and critical cyber-physical system(CPS),the hybrid electric powertrain is significant to mitigate air pollution and improve fuel economy.Energy management strategy(EMS)is playing a key role to improve the...As a complex and critical cyber-physical system(CPS),the hybrid electric powertrain is significant to mitigate air pollution and improve fuel economy.Energy management strategy(EMS)is playing a key role to improve the energy efficiency of this CPS.This paper presents a novel bidirectional long shortterm memory(LSTM)network based parallel reinforcement learning(PRL)approach to construct EMS for a hybrid tracked vehicle(HTV).This method contains two levels.The high-level establishes a parallel system first,which includes a real powertrain system and an artificial system.Then,the synthesized data from this parallel system is trained by a bidirectional LSTM network.The lower-level determines the optimal EMS using the trained action state function in the model-free reinforcement learning(RL)framework.PRL is a fully data-driven and learning-enabled approach that does not depend on any prediction and predefined rules.Finally,real vehicle testing is implemented and relevant experiment data is collected and calibrated.Experimental results validate that the proposed EMS can achieve considerable energy efficiency improvement by comparing with the conventional RL approach and deep RL.展开更多
The parallel corporate average fuel consumption(CAFC)and new energy vehicle(NEV)credit schemes that have been introduced by the Ministry of Industry and Information Technology of China is an innovative attempt to simu...The parallel corporate average fuel consumption(CAFC)and new energy vehicle(NEV)credit schemes that have been introduced by the Ministry of Industry and Information Technology of China is an innovative attempt to simultaneously regulate conventional gasoline vehicles(CGVs)and NEVs in the passenger vehicle sector that is expected to function as a long-term management mechanism for CGVs to be more energy-efficient and NEVs to be well-promoted.This will have a significant impact on trends in China’s automotive industry and automakers’business decisions.Taking the cases of four typical automakers with different levels of average fuel economy in their CGVs and advanced NEV production,scenario analysis has been applied to generate these automakers’alternatives in relation to compliance with the dual-credit regulations in force from 2017 to 2020 based on the Interim Measures on the Joint Management of CAFC and NEV Credits(Draft).These automakers’alternative approaches to compliance are compared.Further,in view of the financial losses as a result of halted production if they fail to comply,the values of CAFC and NEV credits and corresponding influencing factors are analyzed from the automakers’perspective.Finally,the most cost-effective compliance strategies for these automakers are summarized and suggested improvements in the regulations are proposed for the government.展开更多
The in-vehicle volatile organic compounds （VOCs） concentrations gains the attention of both car producers and users. In the present study, an attempt was made to determine if analysis of air samples collected from a...The in-vehicle volatile organic compounds （VOCs） concentrations gains the attention of both car producers and users. In the present study, an attempt was made to determine if analysis of air samples collected from an unconditioned car cabin can be used as a quality control measure. The VOCs composition of in-vehicle air was analyzed by means of active sampling on Carbograph 1TD and Tenax TA sorbents, followed by thermal desorption and simultaneous analysis on flame ionization and mass detector （TD-GC/FID-MS）. Nine newly produced cars of the same brand and model were chosen for this study. Within these, four of the vehicles were equipped with identical interior materials and five others differed in terms of upholstery and the presence of a sunroof; one car was convertible. The sampling event took place outside of the car assembly plant and the cars tested left the assembly line no later than 24 hr before the sampling took place. More than 250 compounds were present in the samples collected; the identification of more than 160 was confirmed by comparative mass spectra analysis and 80 were confirmed by both comparison with single/multiple compounds standards and mass spectra analysis. In general, aliphatic hydrocarbons represented more than 60% of the total VOCs （TVOC） determined. Depending on the vehicle, the concentration of aromatic hydrocarbons varied from 12% to 27% of total VOCs. The very short period between car production and sampling of the in-vehicle air permits the assumption that the entire TVOC originates from off-gassing of interior materials. The results of this study expand the knowledge of in-vehicle pollution by presenting information about car cabin air quality immediately after car production.展开更多
Lithium-ion batteries(LIBs)have been widely applied in portable electronic devices and electric vehicles.With the booming of the respective markets,a huge quantity of spent LIBs that typically use either LiFePO_(4) or...Lithium-ion batteries(LIBs)have been widely applied in portable electronic devices and electric vehicles.With the booming of the respective markets,a huge quantity of spent LIBs that typically use either LiFePO_(4) or Li N_(x)Co_(y)Mn_(z)O_(2) cathode materials will be produced in the very near future,imposing significant pressure for the development of suitable disposal/recycling technologies,in terms of both environmental protection and resource reclaiming.In this review,we firstly do a comprehensive summary of the-state-of-art technologies to recycle Li N_(x)Co_(y)Mn_(z)O_(2) and LiFePO_(4)-based LIBs,in the aspects of pretreatment,hydrometallurgical recycling,and direct regeneration of the cathode materials.This closed-loop strategy for cycling cathode materials has been regarded as an ideal approach considering its economic benefit and environmental friendliness.Afterward,as for the exhausted anode materials,we focus on the utilization of exhausted anode materials to obtain other functional materials,such as graphene.Finally,the existing challenges in recycling the LiFePO_(4) and Li N_(x)Co_(y)Mn_(z)O_(2) cathodes and graphite anodes for industrial-scale application are discussed in detail;and the possible strategies for these issues are proposed.We expect this review can provide a roadmap towards better technologies for recycling LIBs,shed light on the future development of novel battery recycling technologies to promote the environmental benignity and economic viability of the battery industry and pave way for the large-scale application of LIBs in industrial fields in the near future.展开更多
State of charge(SOC) is a key parameter of lithium-ion battery. In this paper, a finite difference extended Kalman filter(FDEKF)with Hybrid Pulse Power Characterization(HPPC) parameters identification is proposed to e...State of charge(SOC) is a key parameter of lithium-ion battery. In this paper, a finite difference extended Kalman filter(FDEKF)with Hybrid Pulse Power Characterization(HPPC) parameters identification is proposed to estimate the SOC. The finite difference(FD) algorithm is benefit to compute the partial derivative of nonlinear function, which can reduce the linearization error generated by the extended Kalman filter(EKF). The FDEKF algorithm can reduce the computational load of controller in engineering practice without solving the Jacobian matrix. It is simple of dynamic model of lithium-ion battery to adopt a secondorder resistor-capacitor(2 RC) network, the parameters of which are identified by the HPPC. Two conditions, both constant current discharge(CCD) and urban dynamometer driving schedule(UDDS), are utilized to validate the FDEKF algorithm.Comparing convergence rate and accuracy between the FDEKF and the EKF algorithm, it can be seen that the former is a better candidate to estimate the SOC.展开更多
Typical multidisciplinary design optimization（MDO） has gradually been proposed to balance performances of lightweight, noise, vibration and harshness（NVH） and safety for instrument panel（IP） structure in the aut...Typical multidisciplinary design optimization（MDO） has gradually been proposed to balance performances of lightweight, noise, vibration and harshness（NVH） and safety for instrument panel（IP） structure in the automotive development. Nevertheless, plastic constitutive relation of Polypropylene（PP） under different strain rates, has not been taken into consideration in current reliability-based and collaborative IP MDO design. In this paper, based on tensile test under different strain rates, the constitutive relation of Polypropylene material is studied. Impact simulation tests for head and knee bolster are carried out to meet the regulation of FMVSS 201 and FMVSS 208, respectively. NVH analysis is performed to obtain mainly the natural frequencies and corresponding mode shapes, while the crashworthiness analysis is employed to examine the crash behavior of IP structure. With the consideration of lightweight, NVH, head and knee bolster impact performance, design of experiment（DOE）, response surface model（RSM）, and collaborative optimization（CO） are applied to realize the determined and reliability-based optimizations, respectively. Furthermore, based on multi-objective genetic algorithm（MOGA）, the optimal Pareto sets are completed to solve the multi-objective optimization（MOO） problem. The proposed research ensures the smoothness of Pareto set, enhances the ability of engineers to make a comprehensive decision about multi-objectives and choose the optimal design, and improves the quality and efficiency of MDO.展开更多
Because pixel values of foggy images are irregularly higher than those of images captured in normal weather(clear images),it is difficult to extract and express their texture.No method has previously been developed to...Because pixel values of foggy images are irregularly higher than those of images captured in normal weather(clear images),it is difficult to extract and express their texture.No method has previously been developed to directly explore the relationship between foggy images and semantic segmentation images.We investigated this relationship and propose a generative adversarial network(GAN)for foggy image semantic segmentation(FISS GAN),which contains two parts:an edge GAN and a semantic segmentation GAN.The edge GAN is designed to generate edge information from foggy images to provide auxiliary information to the semantic segmentation GAN.The semantic segmentation GAN is designed to extract and express the texture of foggy images and generate semantic segmentation images.Experiments on foggy cityscapes datasets and foggy driving datasets indicated that FISS GAN achieved state-of-the-art performance.展开更多
The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension （ECAS） has excellent performance in flexible height adjust...The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension （ECAS） has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control （VSC） technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15°. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.展开更多
In order to improve the reliability in torque calculation of SRM,an accurate nonlinear torque model regresses by recursive robust least squares support vector regression(RR-LSSVR)is proposed in this paper.The model is...In order to improve the reliability in torque calculation of SRM,an accurate nonlinear torque model regresses by recursive robust least squares support vector regression(RR-LSSVR)is proposed in this paper.The model is in terms of a segmented-rotor switched reluctance motor(SSRM).The characteristics of the SSRM is introduced to show its nonlinear characteristics both in magnetic and torque.Then,its mathematic model is established,and an accurate inductance measurement method and a torque calculation method are presented.After this,the principle of the RR-LSSVR and why it can adjust weights according to errors are described.The model used the RR-LSSVR algorithm shows an outstanding capability in accuracy and quickness compared with other algorithms.Finally,to further validate the accuracy of the proposed model in practical application,simulation and experiment are designed based on a 16/10 SSRM.展开更多
In this paper, a multi-physics simulation model capable of electromagnetic noise prediction is established, and the effectiveness of the established simulation model in predicting and evaluating electromagnetic noise ...In this paper, a multi-physics simulation model capable of electromagnetic noise prediction is established, and the effectiveness of the established simulation model in predicting and evaluating electromagnetic noise is verified. Based on the verified motor model, a rotor step skewing model which can affect electromagnetic noise is proposed, and the influence of the skewing angle on electromagnetic noise is investigated in detail. By studying the spectral characteristics of the low-order radial magnetic force which has a great influence on electromagnetic noise, the distribution of electromagnetic noise characteristics of the permanent magnet synchronous motor(PMSM) with or without the rotor step skewing is compared and analyzed. Therefore, it lays a technological foundation for predicting and suppressing the electromagnetic vibration noise of electric vehicle(EV) driving motor in the electromagnetic design.展开更多
In this study,the particle size-resolved distribution from a China-3 certificated light-duty diesel vehicle was measured by using a portable emission measurement system（PEMS）.In order to examine the influences of ve...In this study,the particle size-resolved distribution from a China-3 certificated light-duty diesel vehicle was measured by using a portable emission measurement system（PEMS）.In order to examine the influences of vehicle specific power（VSP） and high-altitude operation,measurements were conducted at 8 constant speeds,which ranged from 10 to 80 km/hr at10 km/hr intervals,and two different high altitudes,namely 2200 and 3200 m.The results demonstrated that the numbers of particles in all size ranges decreased significantly as VSP increased when the test vehicle was running at lower speeds（〈 20 km/hr）,while at a moderate speed（between 30 and 60 km/hr）,the particle number was statistically insensitive to increase VSP.Under high-speed cruising conditions,the numbers of ultrafine particles and PM2.5were insensitive to changes in VSP,but the numbers of nanoparticles and PM10 surged considerably.An increase in the operational altitude of the test vehicle resulted in increased particle number emissions at low and high driving speeds;however,particle numbers obtained at moderate speeds decreased as altitude rose.When the test vehicle was running at moderate speeds,particle numbers measured at the two altitudes were very close,except for comparatively higher number concentrations of nanoparticles measured at 2200 m.展开更多
The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of...The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.展开更多
It is an inevitable trend of sustainable manufacturing to replace flood and dry machining with minimum quantity lubrication(MQL)technology.Nevertheless,for aeronautical difficult-tomachine materials,MQL couldn’t meet...It is an inevitable trend of sustainable manufacturing to replace flood and dry machining with minimum quantity lubrication(MQL)technology.Nevertheless,for aeronautical difficult-tomachine materials,MQL couldn’t meet the high demand of cooling and lubrication due to high heat generation during machining.Nano-biolubricants,especially non-toxic carbon group nano-enhancers(CGNs)are used,can solve this technical bottleneck.However,the machining mechanisms under lubrication of CGNs are unclear at complex interface between tool and workpiece,which characterized by high temperature,pressure,and speed,limited its application in factories and necessitates in-depth understanding.To fill this gap,this study concentrates on the comprehensive quantitative assessment of tribological characteristics based on force,tool wear,chip,and surface integrity in titanium alloy and nickel alloy machining and attempts to answer mechanisms systematically.First,to establish evaluation standard,the cutting mechanisms and performance improvement behavior covering antifriction,antiwear,tool failure,material removal,and surface formation of MQL were revealed.Second,the unique film formation and lubrication behaviors of CGNs in MQL turning,milling,and grinding are concluded.The influence law of molecular structure and micromorphology of CGNs was also answered and optimized options were recommended by considering diverse boundary conditions.Finally,in view of CGNs limitations in MQL,the future development direction is proposed,which needs to be improved in thermal stability of lubricant,activity of CGNs,controllable atomization and transportation methods,and intelligent formation of processing technology solutions.展开更多
基金supported by the International Science and Technology Cooperation Program of China(Grant No.2016YFE0102200)the National Natural Science Foundation of China(Grant No.61773234)+1 种基金the National Key R&D Program of China(Grant No.2108YFB0105004)and Beijing Municipal Science and Technology Commission(Grant Nos.D171100005117001&D171100005117002)
文摘Intelligent connected vehicles(ICVs) are believed to change people's life in the near future by making the transportation safer,cleaner and more comfortable. Although many prototypes of ICVs have been developed to prove the concept of autonomous driving and the feasibility of improving traffic efficiency, there still exists a significant gap before achieving mass production of high-level ICVs. The objective of this study is to present an overview of both the state of the art and future perspectives of key technologies that are needed for future ICVs. It is a challenging task to review all related works and predict their future perspectives, especially for such a complex and interdisciplinary area of research. This article is organized to overview the ICV key technologies by answering three questions: what are the milestones in the history of ICVs; what are the electronic components needed for building an ICV platform; and what are the essential algorithms to enable intelligent driving? To answer the first question, the article has reviewed the history and the development milestones of ICVs. For the second question, the recent technology advances in electrical/electronic architecture, sensors, and actuators are presented. For the third question, the article focuses on the algorithms in decision making, as the perception and control algorithm are covered in the development of sensors and actuators. To achieve correct decision-making, there exist two different approaches: the principle-based approach and data-driven approach. The advantages and limitations of both approaches are explained and analyzed. Currently automotive engineers are concerned more with the vehicle platform technology, whereas the academic researchers prefer to focus on theoretical algorithms. However, only by incorporating elements from both worlds can we accelerate the production of high-level ICVs.
基金supported by the National Natural Science Foundation of China (Grant Nos 51005115, 51005248)the Science Fund of State Key Laboratory of Automotive Safety and Energy (Grant No KF11201)NUAA Research Funding (Grant No NS2010058)
文摘A novel electric power steering system(EPS) integrated with active front steering(AFS) is developed.It has functions of both AFS system and EPS system with two actuator units:the AFS actuator unit and the EPS actuator unit.The AFS actuator unit controls the displacement transfer behavior of the steering system,and improves the handling stability under adverse road conditions by varying the steering ratio directly related to the speed and road conditions.The EPS actuator unit controls the force transfer behavior of the steering system,and improves the steering portability and road feel of the vehicle.Based on a dynamic model,the mixed H2/H∞ control strategy of the EPS actuator and the active steering intervention control strategy of the AFS actuator are designed.The simulation indicates that the novel EPS system with the designed control strategies has obvious advantages in vehicle handling stability and the driver's road feel over the traditional EPS system,and extends the vehicle's steering performance.
基金supported by the National Natural Science Foundation of China (Grant No. 10772152)the Natural Science Foundation of Shandong Province of China (Grant No. ZR2010FM008)
文摘The lateral control for lane changing of intelligent vehicle on curved road in automatic highway systems was studied. Based on trapezoidal acceleration profile, considering the curvature difference between starting lane and target lane, a new virtual trajectory planning method for lane changing on curved road was presented, and the calculating formulas for ideal states of vehicle in the inertial coordinate system during a lane changing maneuver were established. Applying the predetermined trajectory, the reference yaw angle and yaw rate for lane changing were generated. On the assumption that the information on yaw rate of vehicle can be measured with on-board sensors and based on the lateral dynamical model of vehicle, the yaw-rate-tracking control law was designed by applying nonsingular terminal sliding mode technology. Based on Lyapunov function method, the finite-time convergence property of the system was obtained from the phase-plane analysis. Simulation results showed that if the curvature difference between starting lane and target lane was not considered, then at the finishing time of lane changing, it was impossible to avoid the deviation of the virtual trajectory panned from the target lane, which increased with the decrease of curvature radius. With the trajectory planning method and yaw rate-tracking control law proposed in this paper and considering the curvature difference between the starting lane and target lane, the desired virtual trajectory for lane changing without deviation was obtained and the expected tracking performance was also verified by the simulation.
文摘Magnesium is one of the largely available elements in the earth’s crust. It has a low structural density with high specific strength. This unique material property has forced an increase in the use of magnesium and its alloys in various applications pertaining to industrial sector,automobiles, aerospace and biomedical. Since magnesium is a highly reactive metal, it is prone to higher rate of corrosion as compared to its counterparts. Thus, it is essential to analyze the corrosion behavior of magnesium and its alloys in its applications. An appropriate process is to be followed in the design and development of magnesium alloys which overcome the limitations of magnesium and enhance the desired material properties in accordance to their applications. This review paper summarizes the importance of magnesium and its material properties. The influence of various alloying elements on the mechanical properties of magnesium is reviewed. The broad classification of Mg alloys and their behavioral trends are detailed. The corrosion behavior of magnesium and the influence of corrosion products on the material characteristics of magnesium, in aqueous medium, are discussed. The manufacturing techniques of magnesium alloys along with the secondary techniques are also covered. The various applications and the limitations of magnesium in these applications are covered. A complete section is dedicated towards detailing the recent trends of magnesium(Mg) alloys, i.e., the biodegradable nature and applications of Mg alloys. The influence of biocorrosion on Mg alloys and techniques to overcome it have been deliberated. This paper provides a thorough review on recent developments of magnesium with respect to engineering applications.
基金financially supported by the National Natural Science Foundation of China (No. 51404030)the National Key Technologies Research and Development Program (No. 2016YFB0100400)+2 种基金the Natural Science Foundation of Beijing Municipality (No. 3154043)the Beijing Science and Technology Plan (No. Z151100000115015)the Beijing Nova Program (No. Z161100004916096)
文摘In this work, a scalable and cost-effective method including mechanical milling, centrifugation and spray drying was developed to fabricate Si nanoparticles.The synthesized Si nanoparticles show an average size of 62 nm and exhibit a narrow particle size distribution. The influence of particle sizes on electrochemical performance of Si-based electrode was investigated, and it is found that as the particle size decreases in the studied range, the Si particles show a lower specific capacity and a higher irreversible capacity loss(ICL). Furthermore, an oxide layer with thickness of ～3 nm was detected on the surface of the as-received Si nanoparticles, and this layer can be effectively removed by hydrofluoric acid(HF) etching,resulting in much improved electrochemical performance over the as-received samples.
基金supported by the State Key Laboratory of Engines (No. 200906)the National Natural Science Foundation of China (No. 40805053)
文摘On-road emission and fuel consumption （FC） levels for Euro Ⅲ and Ⅳ buses fueled on diesel and compressed natural gas （CNG） were compared, and emission and FC characteristics of buses were analyzed based on approximately 28,700 groups of instantaneous data obtained in Beijing using a portable emissions measurement system （PEMS）. The experimental results revealed that NOx and PM emissions from CNG buses were decreased by 72.0% and 82.3% respectively, compared with Euro IV diesel buses. Similarly, these emissions were reduced by 75.2% and 96.3% respectively, compared with Euro III diesel buses. In addition, CO2, CO, HC, NOx, PM emissions and FC of Euro IV diesel buses were reduced by 26.4%, 75.2%, 73.6%, 11.4%, 79.1%, and 26.0%, respectively, relative to Euro Ⅲ diesel buses. The CO2, CO, HC, NOx, PM emissions and FC factors all decreased with bus speed increased, while increased as bus acceleration increased. At the same time, the emission/FC rates as well as the emission/FC factors exhibited a strong positive correlation with the vehicle specific power （VSP）. They all were the lowest when VSP 〈 0, and then rapidly increased as VSP increased. Furthermore, both the emission/FC rates and emission/FC factors were the highest at accelerations, higher at cruise speeds, and the lowest at decelerations for non-idling buses. These results can provide a base reference to further estimate bus emission and FC inventories in Beijing.
基金supported by the National Natural Science Foundation of China(Nos.U1564206,U1764258)the National Key R&D Program of China(No.2018YFB0105700)+1 种基金the support from China Scholarship Council(No.201806030115)supported by the Department of Energy(DOE),Office of Electricity(OE)at Oak Ridge National Laboratory managed by UL-Battelle LLC under contract DE-AC05-00OR22725。
文摘In this paper,overcharge behaviors and thermal runaway(TR)features of large format lithium-ion(Liion)cells with different cathode materials(LiFePO4(LFP),Li[Ni_(1/3)Co_(1/3)Mn_(1/3)]O_(2)(NCM111),Li[Ni_(0.6)Co_(0.2)Mn_(0.2)]O_(2)(NCM622)and Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM811))were investigated.The results showed that,under the same overcharge condition,the TR of LFP Li-ion cell occurred earlier compared with the NCM Li-ion cells,indicating its poor overcharge tolerance and high TR risk.However,when TR occurred,LFP Li-ion cell exhibited lower maximum temperature and mild TR response.All NCM Liion cells caught fire or exploded during TR,while the LFP Li-ion cell only released a large amount of smoke without fire.According to the overcharge behaviors and TR features,a safety assessment score system was proposed to evaluate the safety of the cells.In short,NCM Li-ion cells have better performance in energy density and overcharge tolerance(or low TR risk),while LFP Li-ion cell showed less severe response to overcharging(or less TR hazards).For NCM Li-ion cells,as the ratio of nickel in cathode material increases,the thermal stability of the cathode materials becomes poorer,and the TR hazards increase.Such a comparison study on large format Li-ion cells with different cathode materials can provide deeper insights into the overcharge behaviors and TR features,and provide guidance for engineers to reasonably choose battery materials in automotive applications.
基金supported in part by the National Natural Science Foundation of China(61533019,91720000)Beijing Municipal Science and Technology Commission(Z181100008918007)the Intel Collaborative Research Institute for Intelligent and Automated Connected Vehicles(pICRI-IACVq)
文摘As a complex and critical cyber-physical system(CPS),the hybrid electric powertrain is significant to mitigate air pollution and improve fuel economy.Energy management strategy(EMS)is playing a key role to improve the energy efficiency of this CPS.This paper presents a novel bidirectional long shortterm memory(LSTM)network based parallel reinforcement learning(PRL)approach to construct EMS for a hybrid tracked vehicle(HTV).This method contains two levels.The high-level establishes a parallel system first,which includes a real powertrain system and an artificial system.Then,the synthesized data from this parallel system is trained by a bidirectional LSTM network.The lower-level determines the optimal EMS using the trained action state function in the model-free reinforcement learning(RL)framework.PRL is a fully data-driven and learning-enabled approach that does not depend on any prediction and predefined rules.Finally,real vehicle testing is implemented and relevant experiment data is collected and calibrated.Experimental results validate that the proposed EMS can achieve considerable energy efficiency improvement by comparing with the conventional RL approach and deep RL.
基金This study is sponsored by the Natural Science Foundation of Beijing(9162008)Ministry of Science and Technol-ogy of China(ZLY2015017).
文摘The parallel corporate average fuel consumption(CAFC)and new energy vehicle(NEV)credit schemes that have been introduced by the Ministry of Industry and Information Technology of China is an innovative attempt to simultaneously regulate conventional gasoline vehicles(CGVs)and NEVs in the passenger vehicle sector that is expected to function as a long-term management mechanism for CGVs to be more energy-efficient and NEVs to be well-promoted.This will have a significant impact on trends in China’s automotive industry and automakers’business decisions.Taking the cases of four typical automakers with different levels of average fuel economy in their CGVs and advanced NEV production,scenario analysis has been applied to generate these automakers’alternatives in relation to compliance with the dual-credit regulations in force from 2017 to 2020 based on the Interim Measures on the Joint Management of CAFC and NEV Credits(Draft).These automakers’alternative approaches to compliance are compared.Further,in view of the financial losses as a result of halted production if they fail to comply,the values of CAFC and NEV credits and corresponding influencing factors are analyzed from the automakers’perspective.Finally,the most cost-effective compliance strategies for these automakers are summarized and suggested improvements in the regulations are proposed for the government.
基金supported by the Polish Ministry of Scienceand Higher Education(No.N N509 480438)
文摘The in-vehicle volatile organic compounds （VOCs） concentrations gains the attention of both car producers and users. In the present study, an attempt was made to determine if analysis of air samples collected from an unconditioned car cabin can be used as a quality control measure. The VOCs composition of in-vehicle air was analyzed by means of active sampling on Carbograph 1TD and Tenax TA sorbents, followed by thermal desorption and simultaneous analysis on flame ionization and mass detector （TD-GC/FID-MS）. Nine newly produced cars of the same brand and model were chosen for this study. Within these, four of the vehicles were equipped with identical interior materials and five others differed in terms of upholstery and the presence of a sunroof; one car was convertible. The sampling event took place outside of the car assembly plant and the cars tested left the assembly line no later than 24 hr before the sampling took place. More than 250 compounds were present in the samples collected; the identification of more than 160 was confirmed by comparative mass spectra analysis and 80 were confirmed by both comparison with single/multiple compounds standards and mass spectra analysis. In general, aliphatic hydrocarbons represented more than 60% of the total VOCs （TVOC） determined. Depending on the vehicle, the concentration of aromatic hydrocarbons varied from 12% to 27% of total VOCs. The very short period between car production and sampling of the in-vehicle air permits the assumption that the entire TVOC originates from off-gassing of interior materials. The results of this study expand the knowledge of in-vehicle pollution by presenting information about car cabin air quality immediately after car production.
基金supported by the National Natural Science Foundation of China(Nos.51072130,51502045 and 21905202)the Australian Research Council(ARC)through Discovery Early Career Researcher Award(DECRA,No.DE170100871)program。
文摘Lithium-ion batteries(LIBs)have been widely applied in portable electronic devices and electric vehicles.With the booming of the respective markets,a huge quantity of spent LIBs that typically use either LiFePO_(4) or Li N_(x)Co_(y)Mn_(z)O_(2) cathode materials will be produced in the very near future,imposing significant pressure for the development of suitable disposal/recycling technologies,in terms of both environmental protection and resource reclaiming.In this review,we firstly do a comprehensive summary of the-state-of-art technologies to recycle Li N_(x)Co_(y)Mn_(z)O_(2) and LiFePO_(4)-based LIBs,in the aspects of pretreatment,hydrometallurgical recycling,and direct regeneration of the cathode materials.This closed-loop strategy for cycling cathode materials has been regarded as an ideal approach considering its economic benefit and environmental friendliness.Afterward,as for the exhausted anode materials,we focus on the utilization of exhausted anode materials to obtain other functional materials,such as graphene.Finally,the existing challenges in recycling the LiFePO_(4) and Li N_(x)Co_(y)Mn_(z)O_(2) cathodes and graphite anodes for industrial-scale application are discussed in detail;and the possible strategies for these issues are proposed.We expect this review can provide a roadmap towards better technologies for recycling LIBs,shed light on the future development of novel battery recycling technologies to promote the environmental benignity and economic viability of the battery industry and pave way for the large-scale application of LIBs in industrial fields in the near future.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFB0103100)the Science and Technology Special Project of Anhui Province(Grant No.18030901063)
文摘State of charge(SOC) is a key parameter of lithium-ion battery. In this paper, a finite difference extended Kalman filter(FDEKF)with Hybrid Pulse Power Characterization(HPPC) parameters identification is proposed to estimate the SOC. The finite difference(FD) algorithm is benefit to compute the partial derivative of nonlinear function, which can reduce the linearization error generated by the extended Kalman filter(EKF). The FDEKF algorithm can reduce the computational load of controller in engineering practice without solving the Jacobian matrix. It is simple of dynamic model of lithium-ion battery to adopt a secondorder resistor-capacitor(2 RC) network, the parameters of which are identified by the HPPC. Two conditions, both constant current discharge(CCD) and urban dynamometer driving schedule(UDDS), are utilized to validate the FDEKF algorithm.Comparing convergence rate and accuracy between the FDEKF and the EKF algorithm, it can be seen that the former is a better candidate to estimate the SOC.
基金supported by National Hi-tech Research and Development Program of China(863 Program, Grant No. 2007AA04Z132)National Natural Science Foundation of China(Grant No. 51175379)
文摘Typical multidisciplinary design optimization（MDO） has gradually been proposed to balance performances of lightweight, noise, vibration and harshness（NVH） and safety for instrument panel（IP） structure in the automotive development. Nevertheless, plastic constitutive relation of Polypropylene（PP） under different strain rates, has not been taken into consideration in current reliability-based and collaborative IP MDO design. In this paper, based on tensile test under different strain rates, the constitutive relation of Polypropylene material is studied. Impact simulation tests for head and knee bolster are carried out to meet the regulation of FMVSS 201 and FMVSS 208, respectively. NVH analysis is performed to obtain mainly the natural frequencies and corresponding mode shapes, while the crashworthiness analysis is employed to examine the crash behavior of IP structure. With the consideration of lightweight, NVH, head and knee bolster impact performance, design of experiment（DOE）, response surface model（RSM）, and collaborative optimization（CO） are applied to realize the determined and reliability-based optimizations, respectively. Furthermore, based on multi-objective genetic algorithm（MOGA）, the optimal Pareto sets are completed to solve the multi-objective optimization（MOO） problem. The proposed research ensures the smoothness of Pareto set, enhances the ability of engineers to make a comprehensive decision about multi-objectives and choose the optimal design, and improves the quality and efficiency of MDO.
基金supported in part by the National Key Research and Development Program of China(2018YFB1305002)the National Natural Science Foundation of China(62006256)+2 种基金the Postdoctoral Science Foundation of China(2020M683050)the Key Research and Development Program of Guangzhou(202007050002)the Fundamental Research Funds for the Central Universities(67000-31610134)。
文摘Because pixel values of foggy images are irregularly higher than those of images captured in normal weather(clear images),it is difficult to extract and express their texture.No method has previously been developed to directly explore the relationship between foggy images and semantic segmentation images.We investigated this relationship and propose a generative adversarial network(GAN)for foggy image semantic segmentation(FISS GAN),which contains two parts:an edge GAN and a semantic segmentation GAN.The edge GAN is designed to generate edge information from foggy images to provide auxiliary information to the semantic segmentation GAN.The semantic segmentation GAN is designed to extract and express the texture of foggy images and generate semantic segmentation images.Experiments on foggy cityscapes datasets and foggy driving datasets indicated that FISS GAN achieved state-of-the-art performance.
基金Supported by National Natural Science Foundation of China(Grant No.51105177)Jiangsu Provincial Natural Science Foundation of China(Grant No.BK20131255)+2 种基金Research Fund for the Doctoral Program of Higher Education of China(Grant No.20113227120015)Qing Lan Project of Jiangsu Province of China,Scientific Research Foundation for Advanced Talents,Jiangsu University,China(Grant No.11JDG047)Hunan Provincial Natural Science Foundation of China(Grant No.12JJ6036)
文摘The current research of air suspension mainly focuses on the characteristics and design of the air spring. In fact, electronically controlled air suspension （ECAS） has excellent performance in flexible height adjustment during different driving conditions. However, the nonlinearity of the ride height adjusting system and the uneven distribution of payload affect the control accuracy of ride height and the body attitude. Firstly, the three-point measurement system of three height sensors is used to establish the mathematical model of the ride height adjusting system. The decentralized control of ride height and the centralized control of body attitude are presented to design the ride height control system for ECAS. The exact feedback linearization method is adopted for the nonlinear mathematical model of the ride height system. Secondly, according to the hierarchical control theory, the variable structure control （VSC） technique is used to design a controller that is able to adjust the ride height for the quarter-vehicle anywhere, and each quarter-vehicle height control system is independent. Meanwhile, the three-point height signals obtained by three height sensors are tracked to calculate the body pitch and roll attitude over time, and then by calculating the deviation of pitch and roll and its rates, the height control correction is reassigned based on the fuzzy algorithm. Finally, to verify the effectiveness and performance of the proposed combined control strategy, a validating test of ride height control system with and without road disturbance is carried out. Testing results show that the height adjusting time of both lifting and lowering is over 5 s, and the pitch angle and the roll angle of body attitude are less than 0.15°. This research proposes a hierarchical control method that can guarantee the attitude stability, as well as satisfy the ride height tracking system.
基金This work was supported by the National Natural Science Foundation of China under Project 51875261the Natural Science Foundation of Jiangsu Province of China under Projects BK20180046 and BK20170071the“Qinglan project”of Jiangsu Province,and the Key Project of Natural Science Foundation of Jiangsu Higher Education Institutions under Project 17KJA460005.
文摘In order to improve the reliability in torque calculation of SRM,an accurate nonlinear torque model regresses by recursive robust least squares support vector regression(RR-LSSVR)is proposed in this paper.The model is in terms of a segmented-rotor switched reluctance motor(SSRM).The characteristics of the SSRM is introduced to show its nonlinear characteristics both in magnetic and torque.Then,its mathematic model is established,and an accurate inductance measurement method and a torque calculation method are presented.After this,the principle of the RR-LSSVR and why it can adjust weights according to errors are described.The model used the RR-LSSVR algorithm shows an outstanding capability in accuracy and quickness compared with other algorithms.Finally,to further validate the accuracy of the proposed model in practical application,simulation and experiment are designed based on a 16/10 SSRM.
基金supported by the National Natural Science Foundation of China(Grant No.51675324)
文摘In this paper, a multi-physics simulation model capable of electromagnetic noise prediction is established, and the effectiveness of the established simulation model in predicting and evaluating electromagnetic noise is verified. Based on the verified motor model, a rotor step skewing model which can affect electromagnetic noise is proposed, and the influence of the skewing angle on electromagnetic noise is investigated in detail. By studying the spectral characteristics of the low-order radial magnetic force which has a great influence on electromagnetic noise, the distribution of electromagnetic noise characteristics of the permanent magnet synchronous motor(PMSM) with or without the rotor step skewing is compared and analyzed. Therefore, it lays a technological foundation for predicting and suppressing the electromagnetic vibration noise of electric vehicle(EV) driving motor in the electromagnetic design.
基金financially supported by the National Natural Science Foundation of China(Nos.51576016 and 51476012)
文摘In this study,the particle size-resolved distribution from a China-3 certificated light-duty diesel vehicle was measured by using a portable emission measurement system（PEMS）.In order to examine the influences of vehicle specific power（VSP） and high-altitude operation,measurements were conducted at 8 constant speeds,which ranged from 10 to 80 km/hr at10 km/hr intervals,and two different high altitudes,namely 2200 and 3200 m.The results demonstrated that the numbers of particles in all size ranges decreased significantly as VSP increased when the test vehicle was running at lower speeds（〈 20 km/hr）,while at a moderate speed（between 30 and 60 km/hr）,the particle number was statistically insensitive to increase VSP.Under high-speed cruising conditions,the numbers of ultrafine particles and PM2.5were insensitive to changes in VSP,but the numbers of nanoparticles and PM10 surged considerably.An increase in the operational altitude of the test vehicle resulted in increased particle number emissions at low and high driving speeds;however,particle numbers obtained at moderate speeds decreased as altitude rose.When the test vehicle was running at moderate speeds,particle numbers measured at the two altitudes were very close,except for comparatively higher number concentrations of nanoparticles measured at 2200 m.
基金supported by the National Key R&D Program of China under Contract No.2022YFA1602200the International Partnership Program of the Chineses Academy of Sciences under Grant No.211134KYSB20200057the STCF Key Technology Research and Development Project.
文摘The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.
基金supported by the National Natural Science Foundation of China(Nos.51975305 and 51905289)the Major Research Project of Shandong Province(No.2019GGX104040)+2 种基金the Major Science and Technology Innovation Engineering Projects of Shandong Province(No.2019JZZY020111)the Natural Science Foundation of Shandong Province(Nos.ZR2020KE027 and ZR2020ME158)the Applied Basic Research Youth Project of Qingdao science and technology plan(No.19-6-2-63-cg)。
文摘It is an inevitable trend of sustainable manufacturing to replace flood and dry machining with minimum quantity lubrication(MQL)technology.Nevertheless,for aeronautical difficult-tomachine materials,MQL couldn’t meet the high demand of cooling and lubrication due to high heat generation during machining.Nano-biolubricants,especially non-toxic carbon group nano-enhancers(CGNs)are used,can solve this technical bottleneck.However,the machining mechanisms under lubrication of CGNs are unclear at complex interface between tool and workpiece,which characterized by high temperature,pressure,and speed,limited its application in factories and necessitates in-depth understanding.To fill this gap,this study concentrates on the comprehensive quantitative assessment of tribological characteristics based on force,tool wear,chip,and surface integrity in titanium alloy and nickel alloy machining and attempts to answer mechanisms systematically.First,to establish evaluation standard,the cutting mechanisms and performance improvement behavior covering antifriction,antiwear,tool failure,material removal,and surface formation of MQL were revealed.Second,the unique film formation and lubrication behaviors of CGNs in MQL turning,milling,and grinding are concluded.The influence law of molecular structure and micromorphology of CGNs was also answered and optimized options were recommended by considering diverse boundary conditions.Finally,in view of CGNs limitations in MQL,the future development direction is proposed,which needs to be improved in thermal stability of lubricant,activity of CGNs,controllable atomization and transportation methods,and intelligent formation of processing technology solutions.
