To develop emerging electrode materials and improve the performances of batteries,the machine learning techniques can provide insights to discover,design and develop battery new materials in high-throughput way.In thi...To develop emerging electrode materials and improve the performances of batteries,the machine learning techniques can provide insights to discover,design and develop battery new materials in high-throughput way.In this paper,two deep learning models are developed and trained with two feature groups extracted from the Materials Project datasets to predict the battery electrochemical performances including average voltage,specific capacity and specific energy.The deep learning models are trained with the multilayer perceptron as the core.The Bayesian optimization and Monte Carlo methods are applied to improve the prediction accuracy of models.Based on 10 types of ion batteries,the correlation coefficients are maintained above 0.9 compared to DFT calculation results and the mean absolute error of the prediction results for voltages of two models can reach 0.41 V and 0.20 V,respectively.The electrochemical performance prediction times for the two trained models on thousands of batteries are only 72.9 ms and 75.7 ms.Besides,the two deep learning models are applied to approach the screening of emerging electrode materials for sodium-ion and potassium-ion batteries.This work can contribute to a high-throughput computational method to accelerate the rational and fast materials discovery and design.展开更多
The existing research of the automotive side swing door and the closing angle via tests and simulations. In these tests, the closing energy is mainly conducted by measuring the closing energy door closing velocity and...The existing research of the automotive side swing door and the closing angle via tests and simulations. In these tests, the closing energy is mainly conducted by measuring the closing energy door closing velocity and initial door closing angle are usually not taken into consideration, so the accuracy of the test data cannot be ensured, and, meanwhile, simulations require a great deal of manpower and time. Moreover, frequent tests would give rise to the increasing research and development costs. In this paper, in response to the deficiencies of these current methods, the complicated door closing process is decomposed into the closing processes of different subsystems of door, which includes weather strip seal', air-binding effect, door weight, hinge, check-link and latch. Mathematical models of those subsystems are established according to their working principles during the door closing process. In addition to the theoretical research, an Excel-based software using Visual Basic Application programming language is developed to realize the mathematical models, which aims to calculate the energy consumption of the subsystems. The energy consumption of different subsystems of a production vehicle door is measured to verify the accuracy of the calculation sottware developed. The proposed research provides not only the theoretical basis for the future door closing energy research, but also an interactive method and system, effectively improving the quality and efficiency of vehicle door design.展开更多
According to the structural characteristics of the automobile engine bracket, the finite element model of the bracket is established. As the connecting part between the engine and the body, the performance requirement...According to the structural characteristics of the automobile engine bracket, the finite element model of the bracket is established. As the connecting part between the engine and the body, the performance requirements of the automobile engine bracket affect the comfort and the safety of the vehicle directly. Using the RADIOSS solver, the dangerous point of the bracket is analyzed. Under the premise of ensuring its reliability, with the help of OptiStruct software to carry out the topology optimization design, to get the optimal material distribution of the bracket and the final design will meet the performance requirements.展开更多
The development of thermal stress in the exhaust manifold of a gasoline engine is considered.The problem is addresses in the frame of a combined approach wherefluid and structure are coupled using the GT-POWER and STA...The development of thermal stress in the exhaust manifold of a gasoline engine is considered.The problem is addresses in the frame of a combined approach wherefluid and structure are coupled using the GT-POWER and STAR-CCM+software.First,the external characteristic curve of the engine is compared with a one-dimen-sional simulation model,then the parameters of the model are modified until the curve matches the available experimental values.GT-POWER is then used to transfer the inlet boundary data under transient conditions to STAR-CCM+in real-time.The temperature profiles of the inner and outer walls of the exhaust manifold are obtained in this way,together with the thermal stress and thermal deformation of the exhaust manifold itself.Using this information,the original model is improved through the addition of connections.Moreover,the local branch pipes are optimized,leading to significant improvements in terms of thermal stress and thermal deforma-tion of the exhaust manifold(a 7%reduction in the maximum thermal stress).展开更多
In order to realize the accurate obstacle avoidance function of intelligent car, we propose an intelligent car obstacle avoidance system based on optimized fuzzy control algorithm. Firstly, the kinematics model of int...In order to realize the accurate obstacle avoidance function of intelligent car, we propose an intelligent car obstacle avoidance system based on optimized fuzzy control algorithm. Firstly, the kinematics model of intelligent car obstacle avoidance is established, and an efficient environment information collection system composed of multiple sensors is designed to realize the comprehensive collection of obstacle information. Then, the optimized fuzzy control system is adopted to improve the position control accuracy and obstacle avoidance ability. Through the physical debugging and joint simulation of the intelligent car fuzzy controller in the MATLAB and Simulink environment, the simulation results show that the control method can make the collision-free path planned by the intelligent car from the initial state to the obstacle avoidance smoother, and at the same time, the obstacle avoidance of the intelligent car. The actual running distance is reduced by about 16%, which can ensure the practicability of the obstacle avoidance system, provide a new guarantee for the safe operation of the car, and also provide a new idea for the development of the unmanned car.展开更多
In order to realize the accurate obstacle avoidance function of intelligent car, we propose an intelligent car obstacle avoidance system based on optimized fuzzy control algorithm. Firstly, the kinematics model of int...In order to realize the accurate obstacle avoidance function of intelligent car, we propose an intelligent car obstacle avoidance system based on optimized fuzzy control algorithm. Firstly, the kinematics model of intelligent car obstacle avoidance is established, and an efficient environment information collection system composed of multiple sensors is designed to realize the comprehensive collection of obstacle information. Then, the optimized fuzzy control system is adopted to improve the position control accuracy and obstacle avoidance ability. Through the physical debugging and joint simulation of the intelligent car fuzzy controller in the MATLAB and Simulink environment, the simulation results show that the control method can make the collision-free path planned by the intelligent car from the initial state to the obstacle avoidance smoother, and at the same time, the obstacle avoidance of the intelligent car. The actual running distance is reduced by about 16%, which can ensure the practicability of the obstacle avoidance system, provide a new guarantee for the safe operation of the car, and also provide a new idea for the development of the unmanned car.展开更多
Electrocardiogram(ECG)monitoring is used to diagnose cardiovascular diseases,for which wearable electronics have attracted much attention due to their lightweight,comfort,and long-term use.This study developed a weara...Electrocardiogram(ECG)monitoring is used to diagnose cardiovascular diseases,for which wearable electronics have attracted much attention due to their lightweight,comfort,and long-term use.This study developed a wearablemultilead ECG sensing system with on-skin stretchable and conductive silver(Ag)-coated fiber/silicone(AgCF-S)dry adhesives.Tangential and normal adhesion to pigskin(0.43 and 0.20 N/cm2,respectively)was optimized by the active control of fiber density and mixing ratio,resulting in close contact in the electrode–skin interface.The breathableAgCF-S dry electrodewas nonallergenic after continuous fit for 24 h and can be reused/cleaned(>100 times)without loss of adhesion.The AgCF encapsulated inside silicone elastomers was overlapped to construct a dynamic network under repeated stretching(10%strain)and bending(90°)deformations,enabling small intrinsic impedance(0.3,0.1 Hz)and contact impedance variation(0.7 k)in high-frequency vibration(70 Hz).All hard/soft modules of the multilead ECG system were integrated into lightweight clothing and equipped with wireless transmission for signal visualization.By synchronous acquisition of I–III,aVR,aVL,aVF,and V4 lead data,the multilead ECG sensing system was suitable for various scenarios,such as exercise,rest,and sleep,with extremely high signal-to-noise ratios.展开更多
The key components of engineering machinery frequently failed due to working in the high load and high wear operating envir-onment.And the performance of the Fe-based alloy coatings typically employed need to be impro...The key components of engineering machinery frequently failed due to working in the high load and high wear operating envir-onment.And the performance of the Fe-based alloy coatings typically employed need to be improved for fulfilling the service requirements.Herein,a TiC strengthened Fe-based alloy cladding layer,named TiC-Fe coating,was designed and prepared by plasma cladding technology.The frictional wear performance of coating under various loads was tested.The wear morphology of the coating was observed,and its wear mechanism was examined.The results indicated that the TiC-Fe coating was well formed and metallurgically bonded to the Q345C substrate.Its microstructure mainly consisted of Fe-Cr solid solution,α-Fe phase,(Fe,Cr)_(7)C_(3) phase and TiC phase.The coating exhibited an average microhardness of 980 HV0.2,which was about 5.4 times that of the Q345C substrate.The wear mass loss of the TiC-Fe coatings was much smaller than that of the Q345C substrate,which indicated that the wear resistance of the Q345C coating was superior to the substrate,and the wear mechanism of the coating was mainly attributed to the abrasive wear.展开更多
There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to u...There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.展开更多
Zeolite/TiO-2 composite photocatalysts were prepared by adding a certain amount of mordenite in TiO-2, and degradation experiments on toluene through photocatalytic reactions were implemented. In this paper, these pho...Zeolite/TiO-2 composite photocatalysts were prepared by adding a certain amount of mordenite in TiO-2, and degradation experiments on toluene through photocatalytic reactions were implemented. In this paper, these photocatalysts were characterized by using SEM, IR, RAMAN, XRD and UV-Vis to shed light on the microstructure and photocatalytic performance of the composite photocatalysts. The results indicated that the structural hydroxy of zeolite can participate in bonding reaction with TiO-2, the addition of zeolite can greatly reduce the diameter of nanometer TiO-2 particles in the composite photocatalysts, and enhance the ultraviolet light absorptance of the composite photocatalysts. When the percentage content of zeolite reached 20%, the photocatalytic performance of this catalyst would be highest, with the toluene conversion rate up to {94.58%}.展开更多
The launch shudder phenomenon induced by self-excited vibration of driveline was stud- ied with a compact car equipped with AMT as research object. The research showed that self-excited vibration was closely related w...The launch shudder phenomenon induced by self-excited vibration of driveline was stud- ied with a compact car equipped with AMT as research object. The research showed that self-excited vibration was closely related with damping of driveline, the variation of friction coefficient, equiva- lent radius of friction plate and applied force of pressure plate. Six DOFs torsional vibration model of vehicle driveline was established according to the parameters of the certain compact car. The simula- tion was carried out and the result was compared with test data. It was found that the negative slope of friction coefficient with relative slip speed does not necessarily lead to self-excited vibration and the frequency of self-excited vibration on 1st gear is near to the 1st order of torsional natural frequen- cy. The influence of each viscous damping in driveline on self-excited vibration was analyzed by sim- ulation and the results showed that increasing the torsional dampings of half-axles and tires properly was effective to improve launch shudder phenomenon.展开更多
Based on the basic principle of vehicle crash analysis using the finite element method, a car finite element model was built by using Hypermesh software. To simulate the front collision test of the car, the LS-DYNA so...Based on the basic principle of vehicle crash analysis using the finite element method, a car finite element model was built by using Hypermesh software. To simulate the front collision test of the car, the LS-DYNA software is adopted to calculate the deformation of the car and the acceleration time history curves during the crashing process;the anti-impact capability of the car is evaluated from this simulation. The results demonstrate that the improvement of local structure can promote the crashworthiness of the car, but the further improvement needs a major change of the car structure.展开更多
The theory of functionally graded material(FGM)was applied in the fabrication process of PEN(Positive-Electrolyte-Negative),the core component of solid oxide fuel cell(SOFC).To enhance its electrochemical performance,...The theory of functionally graded material(FGM)was applied in the fabrication process of PEN(Positive-Electrolyte-Negative),the core component of solid oxide fuel cell(SOFC).To enhance its electrochemical performance,the functionally graded PEN of planar SOFC was prepared by atmospheric plasma spray(APS).The cross-sectional SEM micrograph and element energy spectrum of the resultant PEN were analyzed.Its interface resistance was also compared with that without the graded layers to investigate the electrochemical performance enhanced by the functionally graded layers.Moreover,a new process, suspension plasma spray(SPS)was applied to preparing the SOFC electrolyte.Higher densification of the coating by SPS,1.61%,is observed,which is helpful to effectively improve its electrical conductivity.The grain size of the electrolyte coating fabricated by SPS is also smaller than that by APS,which is more favourable to obtain the dense electrolyte coatings.To sum up,all mentioned above can prove that the hybrid process of APS and SPS could be a better approach to fabricate the PEN of SOFC stacks,in which APS is for porous electrodes and SPS for dense electrolyte.展开更多
A new kind of commercial truck is presented, which has rear air suspension using leaf spring as guiding rod instead of original leaf spring. ADAMS/Car is used as a tool to build the whole truck model. The designed tr...A new kind of commercial truck is presented, which has rear air suspension using leaf spring as guiding rod instead of original leaf spring. ADAMS/Car is used as a tool to build the whole truck model. The designed truck’s constant-radius cornering analysis and its ride performance simulation analysis under B class random road condition are carried out according to national experimental method standards. Compared the simulation results with the field test results indicate that performance index of the designed air suspension truck’s constant-radius cornering and its ride performance meets the design requirements and reaches its prospective target. And results from simulation are similar to those from tests in value and trend, which indicates the virtual prototype is correct. The model can be used further to optimize suspension parameters and do some design work on the control system of air suspension.展开更多
To improve the suspension performance and steering stability of light vehicles, we built a kinematic simulation model of a whole independent double-wishbone suspension system by using ADAMS software, created random ex...To improve the suspension performance and steering stability of light vehicles, we built a kinematic simulation model of a whole independent double-wishbone suspension system by using ADAMS software, created random excitations of the test platforms of respectively the left and the right wheels according to actual running conditions of a vehicle, and explored the changing patterns of the kinematic characteristic parameters in the process of suspension motion. The irrationality of the suspension guiding mechanism design was pointed out through simulation and analysis, and the existent problems of the guiding mechanism were optimized and calculated. The results show that all the front-wheel alignment parameters, including the camber, the toe, the caster and the inclination, only slightly change within corresponding allowable ranges in design before and after optimization. The optimization reduces the variation of the wheel-center distance from 47.01 mm to a change of 8.28 mm within the allowable range of ?10 mm to 10 mm, promising an improvement of the vehicle steering stability. The optimization also confines the front-wheel sideways slippage to a much smaller change of 2.23 mm; this helps to greatly reduce the wear of tires and assure the straight running stability of the vehicle.展开更多
A collision model, an automobile model and a multi-rigid-body model in PC-crash are analyzed. By simulating a side collision accident between a car and an electric bicycle (EB), a method that reproduces the car-electr...A collision model, an automobile model and a multi-rigid-body model in PC-crash are analyzed. By simulating a side collision accident between a car and an electric bicycle (EB), a method that reproduces the car-electric bicycle side collision accident based on PC-crash is presented according to some important information such as the final position, the contacting location between the cyclist and the car. A result is obtained by comparing with the reproduced result, the deformation of accident vehicle and the surveillance video. The rollover direction and fells-over sliding direction after the collision and the contacting location and wrap motion of cyclist and electric bicycle are fitting in with the real situation better compared with the reconstruction result in PC-crash. Then the responsive-surface method and MONTEKARLO method are used in MATLAB to analyze the uncertainty of the vehicle speed in reproduced scene results. And the range of values of the pre-collision speed is obtained which makes the reproduced result more objective and convincible that could provide the basis of the accident assessment.展开更多
Combining with the development of automated manual transmission (AMT), the various throttle control demands are analyzed under different working conditions of AMT such as tracking acceleration pedal, start, shift an...Combining with the development of automated manual transmission (AMT), the various throttle control demands are analyzed under different working conditions of AMT such as tracking acceleration pedal, start, shift and so on. Based on simulation, the responding throttle control strategies are proposed, and a simple but effective throttle control method is presented. The testing results have proved that the strategies are effective for improving the pedal tracking precision and the qualities of start and shift.展开更多
Associated dynamic performance of the clamping force control valve used in continuously variable transmission (CVT) is optimized. Firstly, the structure and working principle of the valve are analyzed, and then a dy...Associated dynamic performance of the clamping force control valve used in continuously variable transmission (CVT) is optimized. Firstly, the structure and working principle of the valve are analyzed, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, a prototype workpiece of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and five structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the genetic algorithm (GA) with necessary constraints. Finally, the properties of the optimized valve are compared with those of the prototype workpiece, and the results prove that the dynamic performance indexes of the optimized valve are much better than those of the prototype workpiece.展开更多
Electric load simulator(ELS) systems are employed for electric power steering(EPS) test benches to load rack force by precise control. Precise ELS control is strongly influenced by nonlinear factors. When the steering...Electric load simulator(ELS) systems are employed for electric power steering(EPS) test benches to load rack force by precise control. Precise ELS control is strongly influenced by nonlinear factors. When the steering motor rapidly rotates, extra force is directly superimposed on the original static loading error, which becomes one of the main sources of the final error. It is key to achieve ELS precise loading control for the entire EPS test bench. Therefore, a three-part compound control algorithm is proposed to improve the loading accuracy. First, a fuzzy proportional–integral plus feedforward controller with force feedback is presented. Second, a friction compensation algorithm is established to reduce the influence of friction. Then, the relationships between each quantity and the extra force are analyzed when the steering motor rapidly rotates, and a net torque feedforward compensation algorithm is proposed to eliminate the extra force. The compound control algorithm was verified through simulations and experiments. The results show that the tracking performance of the compound control algorithm satisfies the demands of engineering practice, and the extra force in the ELS system can be suppressed by the net torque corresponding to the actuator’s acceleration.展开更多
In order to improve the impactor performance, the dynamic performance of gas-liquid united hydraulic hammer should be optimized. Based on the analysis of the operating principle for the hydraulic impactor, one simulat...In order to improve the impactor performance, the dynamic performance of gas-liquid united hydraulic hammer should be optimized. Based on the analysis of the operating principle for the hydraulic impactor, one simulation model of gas-liquid united hydraulic impactor was built with AMESim software. By setting different simulation parameters, curves of displacement, velocity, acceleration and cavity pressure were obtained under different working conditions. The key component can be obtained by the analysis of activity index. The whole simulation results provide a reliable basis for component selection and parameter optimization of hydraulic impactor.展开更多
基金supported by the National Natural Science Foundation of China(No.52102470).
文摘To develop emerging electrode materials and improve the performances of batteries,the machine learning techniques can provide insights to discover,design and develop battery new materials in high-throughput way.In this paper,two deep learning models are developed and trained with two feature groups extracted from the Materials Project datasets to predict the battery electrochemical performances including average voltage,specific capacity and specific energy.The deep learning models are trained with the multilayer perceptron as the core.The Bayesian optimization and Monte Carlo methods are applied to improve the prediction accuracy of models.Based on 10 types of ion batteries,the correlation coefficients are maintained above 0.9 compared to DFT calculation results and the mean absolute error of the prediction results for voltages of two models can reach 0.41 V and 0.20 V,respectively.The electrochemical performance prediction times for the two trained models on thousands of batteries are only 72.9 ms and 75.7 ms.Besides,the two deep learning models are applied to approach the screening of emerging electrode materials for sodium-ion and potassium-ion batteries.This work can contribute to a high-throughput computational method to accelerate the rational and fast materials discovery and design.
基金supported by Shanghai Automotive Industry Development Foundation of China (Grant No. 0903)R&D Project of Science and Technology Commission of Shanghai Municipality of China (Grant No. 08DZ1150306)
文摘The existing research of the automotive side swing door and the closing angle via tests and simulations. In these tests, the closing energy is mainly conducted by measuring the closing energy door closing velocity and initial door closing angle are usually not taken into consideration, so the accuracy of the test data cannot be ensured, and, meanwhile, simulations require a great deal of manpower and time. Moreover, frequent tests would give rise to the increasing research and development costs. In this paper, in response to the deficiencies of these current methods, the complicated door closing process is decomposed into the closing processes of different subsystems of door, which includes weather strip seal', air-binding effect, door weight, hinge, check-link and latch. Mathematical models of those subsystems are established according to their working principles during the door closing process. In addition to the theoretical research, an Excel-based software using Visual Basic Application programming language is developed to realize the mathematical models, which aims to calculate the energy consumption of the subsystems. The energy consumption of different subsystems of a production vehicle door is measured to verify the accuracy of the calculation sottware developed. The proposed research provides not only the theoretical basis for the future door closing energy research, but also an interactive method and system, effectively improving the quality and efficiency of vehicle door design.
文摘According to the structural characteristics of the automobile engine bracket, the finite element model of the bracket is established. As the connecting part between the engine and the body, the performance requirements of the automobile engine bracket affect the comfort and the safety of the vehicle directly. Using the RADIOSS solver, the dangerous point of the bracket is analyzed. Under the premise of ensuring its reliability, with the help of OptiStruct software to carry out the topology optimization design, to get the optimal material distribution of the bracket and the final design will meet the performance requirements.
基金supported by the Basic Ability Improvement Project for Young and Middle-Aged Teachers in Guangxi Universities,Project No.2021KY0792.
文摘The development of thermal stress in the exhaust manifold of a gasoline engine is considered.The problem is addresses in the frame of a combined approach wherefluid and structure are coupled using the GT-POWER and STAR-CCM+software.First,the external characteristic curve of the engine is compared with a one-dimen-sional simulation model,then the parameters of the model are modified until the curve matches the available experimental values.GT-POWER is then used to transfer the inlet boundary data under transient conditions to STAR-CCM+in real-time.The temperature profiles of the inner and outer walls of the exhaust manifold are obtained in this way,together with the thermal stress and thermal deformation of the exhaust manifold itself.Using this information,the original model is improved through the addition of connections.Moreover,the local branch pipes are optimized,leading to significant improvements in terms of thermal stress and thermal deforma-tion of the exhaust manifold(a 7%reduction in the maximum thermal stress).
文摘In order to realize the accurate obstacle avoidance function of intelligent car, we propose an intelligent car obstacle avoidance system based on optimized fuzzy control algorithm. Firstly, the kinematics model of intelligent car obstacle avoidance is established, and an efficient environment information collection system composed of multiple sensors is designed to realize the comprehensive collection of obstacle information. Then, the optimized fuzzy control system is adopted to improve the position control accuracy and obstacle avoidance ability. Through the physical debugging and joint simulation of the intelligent car fuzzy controller in the MATLAB and Simulink environment, the simulation results show that the control method can make the collision-free path planned by the intelligent car from the initial state to the obstacle avoidance smoother, and at the same time, the obstacle avoidance of the intelligent car. The actual running distance is reduced by about 16%, which can ensure the practicability of the obstacle avoidance system, provide a new guarantee for the safe operation of the car, and also provide a new idea for the development of the unmanned car.
文摘In order to realize the accurate obstacle avoidance function of intelligent car, we propose an intelligent car obstacle avoidance system based on optimized fuzzy control algorithm. Firstly, the kinematics model of intelligent car obstacle avoidance is established, and an efficient environment information collection system composed of multiple sensors is designed to realize the comprehensive collection of obstacle information. Then, the optimized fuzzy control system is adopted to improve the position control accuracy and obstacle avoidance ability. Through the physical debugging and joint simulation of the intelligent car fuzzy controller in the MATLAB and Simulink environment, the simulation results show that the control method can make the collision-free path planned by the intelligent car from the initial state to the obstacle avoidance smoother, and at the same time, the obstacle avoidance of the intelligent car. The actual running distance is reduced by about 16%, which can ensure the practicability of the obstacle avoidance system, provide a new guarantee for the safe operation of the car, and also provide a new idea for the development of the unmanned car.
基金supported by the Natural Science Foundation of Guangdong Province,China(No.2021B1515020087)the National Natural Science Foundation of China(No.51905178)the Climbing Program Foundation of Guangdong Province(No.pdjh2022a0024).
文摘Electrocardiogram(ECG)monitoring is used to diagnose cardiovascular diseases,for which wearable electronics have attracted much attention due to their lightweight,comfort,and long-term use.This study developed a wearablemultilead ECG sensing system with on-skin stretchable and conductive silver(Ag)-coated fiber/silicone(AgCF-S)dry adhesives.Tangential and normal adhesion to pigskin(0.43 and 0.20 N/cm2,respectively)was optimized by the active control of fiber density and mixing ratio,resulting in close contact in the electrode–skin interface.The breathableAgCF-S dry electrodewas nonallergenic after continuous fit for 24 h and can be reused/cleaned(>100 times)without loss of adhesion.The AgCF encapsulated inside silicone elastomers was overlapped to construct a dynamic network under repeated stretching(10%strain)and bending(90°)deformations,enabling small intrinsic impedance(0.3,0.1 Hz)and contact impedance variation(0.7 k)in high-frequency vibration(70 Hz).All hard/soft modules of the multilead ECG system were integrated into lightweight clothing and equipped with wireless transmission for signal visualization.By synchronous acquisition of I–III,aVR,aVL,aVF,and V4 lead data,the multilead ECG sensing system was suitable for various scenarios,such as exercise,rest,and sleep,with extremely high signal-to-noise ratios.
基金supported by National Natural Science Foundation of China(No.52130509,92166105)the Science and Technology Innovation Program of Hunan Province(No.2021RC3096)145 project and Natural Science Foundation of Hunan Province(No.2023JJ30038).
文摘The key components of engineering machinery frequently failed due to working in the high load and high wear operating envir-onment.And the performance of the Fe-based alloy coatings typically employed need to be improved for fulfilling the service requirements.Herein,a TiC strengthened Fe-based alloy cladding layer,named TiC-Fe coating,was designed and prepared by plasma cladding technology.The frictional wear performance of coating under various loads was tested.The wear morphology of the coating was observed,and its wear mechanism was examined.The results indicated that the TiC-Fe coating was well formed and metallurgically bonded to the Q345C substrate.Its microstructure mainly consisted of Fe-Cr solid solution,α-Fe phase,(Fe,Cr)_(7)C_(3) phase and TiC phase.The coating exhibited an average microhardness of 980 HV0.2,which was about 5.4 times that of the Q345C substrate.The wear mass loss of the TiC-Fe coatings was much smaller than that of the Q345C substrate,which indicated that the wear resistance of the Q345C coating was superior to the substrate,and the wear mechanism of the coating was mainly attributed to the abrasive wear.
基金supported by National Natural Science Foundation of China (Grant No. 50875173)Shanghai Municipal Education Commission Key Foundation of China (Grant No. 09ZZ157)Shanghai Leading Academic Discipline Project of China (Grant No. J50503)
文摘There are two kinds of internationally recognized approaches in terms of lightweight design.One is based on fatigue accumulated damage theory to achieve better reliability by optimal structural design; another is to use high performance lightweight materials.The former method takes very few considerations on the structural strengthening effects caused by the massive small loads in service.In order to ensure safety,the design is usually conservative,but the strength potential of the component is not fully exerted.In the latter method,cost is the biggest obstacle to lightweight materials in automotive applications.For the purpose of light weighting design on a fuel cell vehicle,the new design method is applied on drive shafts.The method is based on the low amplitude load strengthening characteristics of the material,and allows the stress,corresponding to test load,to enter into the strengthened range of the material.Under this condition,the light weighting design should assure that the reliability of the shaft is not impaired,even maximizes the strength potential of machine part in order to achieve the weight reduction and eventually to reduce the cost.At last,the feasibility of the design is verified by means of strength analysis and modal analysis based on the CAD model of light weighted shaft.The design applies to the load case of half shaft in independent axle,also provides technological reference for the structural lightweight design of vehicles and other machineries.
文摘Zeolite/TiO-2 composite photocatalysts were prepared by adding a certain amount of mordenite in TiO-2, and degradation experiments on toluene through photocatalytic reactions were implemented. In this paper, these photocatalysts were characterized by using SEM, IR, RAMAN, XRD and UV-Vis to shed light on the microstructure and photocatalytic performance of the composite photocatalysts. The results indicated that the structural hydroxy of zeolite can participate in bonding reaction with TiO-2, the addition of zeolite can greatly reduce the diameter of nanometer TiO-2 particles in the composite photocatalysts, and enhance the ultraviolet light absorptance of the composite photocatalysts. When the percentage content of zeolite reached 20%, the photocatalytic performance of this catalyst would be highest, with the toluene conversion rate up to {94.58%}.
基金Supported by the National Natural Science Foundation of China(51175379)
文摘The launch shudder phenomenon induced by self-excited vibration of driveline was stud- ied with a compact car equipped with AMT as research object. The research showed that self-excited vibration was closely related with damping of driveline, the variation of friction coefficient, equiva- lent radius of friction plate and applied force of pressure plate. Six DOFs torsional vibration model of vehicle driveline was established according to the parameters of the certain compact car. The simula- tion was carried out and the result was compared with test data. It was found that the negative slope of friction coefficient with relative slip speed does not necessarily lead to self-excited vibration and the frequency of self-excited vibration on 1st gear is near to the 1st order of torsional natural frequen- cy. The influence of each viscous damping in driveline on self-excited vibration was analyzed by sim- ulation and the results showed that increasing the torsional dampings of half-axles and tires properly was effective to improve launch shudder phenomenon.
文摘Based on the basic principle of vehicle crash analysis using the finite element method, a car finite element model was built by using Hypermesh software. To simulate the front collision test of the car, the LS-DYNA software is adopted to calculate the deformation of the car and the acceleration time history curves during the crashing process;the anti-impact capability of the car is evaluated from this simulation. The results demonstrate that the improvement of local structure can promote the crashworthiness of the car, but the further improvement needs a major change of the car structure.
基金Project(50675081)supported by the National Natural Science Foundation of ChinaProject(20080440940)supported by China Postdoctoral Science Foundation
文摘The theory of functionally graded material(FGM)was applied in the fabrication process of PEN(Positive-Electrolyte-Negative),the core component of solid oxide fuel cell(SOFC).To enhance its electrochemical performance,the functionally graded PEN of planar SOFC was prepared by atmospheric plasma spray(APS).The cross-sectional SEM micrograph and element energy spectrum of the resultant PEN were analyzed.Its interface resistance was also compared with that without the graded layers to investigate the electrochemical performance enhanced by the functionally graded layers.Moreover,a new process, suspension plasma spray(SPS)was applied to preparing the SOFC electrolyte.Higher densification of the coating by SPS,1.61%,is observed,which is helpful to effectively improve its electrical conductivity.The grain size of the electrolyte coating fabricated by SPS is also smaller than that by APS,which is more favourable to obtain the dense electrolyte coatings.To sum up,all mentioned above can prove that the hybrid process of APS and SPS could be a better approach to fabricate the PEN of SOFC stacks,in which APS is for porous electrodes and SPS for dense electrolyte.
基金Sponsored by the National Science Foundation of Shandong Province (Grant No. Y2005F07) and Innovation Foundation of Jilin University(Grant No.2004CX018).
文摘A new kind of commercial truck is presented, which has rear air suspension using leaf spring as guiding rod instead of original leaf spring. ADAMS/Car is used as a tool to build the whole truck model. The designed truck’s constant-radius cornering analysis and its ride performance simulation analysis under B class random road condition are carried out according to national experimental method standards. Compared the simulation results with the field test results indicate that performance index of the designed air suspension truck’s constant-radius cornering and its ride performance meets the design requirements and reaches its prospective target. And results from simulation are similar to those from tests in value and trend, which indicates the virtual prototype is correct. The model can be used further to optimize suspension parameters and do some design work on the control system of air suspension.
基金the Postdoctoral Science Foundation of China (No. 2004036396)the Foundation of 985- Automotive Engineering of Jilin University
文摘To improve the suspension performance and steering stability of light vehicles, we built a kinematic simulation model of a whole independent double-wishbone suspension system by using ADAMS software, created random excitations of the test platforms of respectively the left and the right wheels according to actual running conditions of a vehicle, and explored the changing patterns of the kinematic characteristic parameters in the process of suspension motion. The irrationality of the suspension guiding mechanism design was pointed out through simulation and analysis, and the existent problems of the guiding mechanism were optimized and calculated. The results show that all the front-wheel alignment parameters, including the camber, the toe, the caster and the inclination, only slightly change within corresponding allowable ranges in design before and after optimization. The optimization reduces the variation of the wheel-center distance from 47.01 mm to a change of 8.28 mm within the allowable range of ?10 mm to 10 mm, promising an improvement of the vehicle steering stability. The optimization also confines the front-wheel sideways slippage to a much smaller change of 2.23 mm; this helps to greatly reduce the wear of tires and assure the straight running stability of the vehicle.
文摘A collision model, an automobile model and a multi-rigid-body model in PC-crash are analyzed. By simulating a side collision accident between a car and an electric bicycle (EB), a method that reproduces the car-electric bicycle side collision accident based on PC-crash is presented according to some important information such as the final position, the contacting location between the cyclist and the car. A result is obtained by comparing with the reproduced result, the deformation of accident vehicle and the surveillance video. The rollover direction and fells-over sliding direction after the collision and the contacting location and wrap motion of cyclist and electric bicycle are fitting in with the real situation better compared with the reconstruction result in PC-crash. Then the responsive-surface method and MONTEKARLO method are used in MATLAB to analyze the uncertainty of the vehicle speed in reproduced scene results. And the range of values of the pre-collision speed is obtained which makes the reproduced result more objective and convincible that could provide the basis of the accident assessment.
基金This project is supported by Provincial Open Foundation of Key Lab forAutomobile of Jiangsu, China (No.KJS02076) and 985 Project of AutomotiveEngineering Innovation Platform of Jilin University, China.
文摘Combining with the development of automated manual transmission (AMT), the various throttle control demands are analyzed under different working conditions of AMT such as tracking acceleration pedal, start, shift and so on. Based on simulation, the responding throttle control strategies are proposed, and a simple but effective throttle control method is presented. The testing results have proved that the strategies are effective for improving the pedal tracking precision and the qualities of start and shift.
基金Key Science-Technology Foundation of Hunan Province, China (No. 05GK2007).
文摘Associated dynamic performance of the clamping force control valve used in continuously variable transmission (CVT) is optimized. Firstly, the structure and working principle of the valve are analyzed, and then a dynamic model is set up by means of mechanism analysis. For the purpose of checking the validity of the modeling method, a prototype workpiece of the valve is manufactured for comparison test, and its simulation result follows the experimental result quite well. An associated performance index is founded considering the response time, overshoot and saving energy, and five structural parameters are selected to adjust for deriving the optimal associated performance index. The optimization problem is solved by the genetic algorithm (GA) with necessary constraints. Finally, the properties of the optimized valve are compared with those of the prototype workpiece, and the results prove that the dynamic performance indexes of the optimized valve are much better than those of the prototype workpiece.
基金Supported by National Natural Science Foundation of China (Grant No. 51505178)China Postdoctoral Science Foundation (Grant No. 2014M561289)。
文摘Electric load simulator(ELS) systems are employed for electric power steering(EPS) test benches to load rack force by precise control. Precise ELS control is strongly influenced by nonlinear factors. When the steering motor rapidly rotates, extra force is directly superimposed on the original static loading error, which becomes one of the main sources of the final error. It is key to achieve ELS precise loading control for the entire EPS test bench. Therefore, a three-part compound control algorithm is proposed to improve the loading accuracy. First, a fuzzy proportional–integral plus feedforward controller with force feedback is presented. Second, a friction compensation algorithm is established to reduce the influence of friction. Then, the relationships between each quantity and the extra force are analyzed when the steering motor rapidly rotates, and a net torque feedforward compensation algorithm is proposed to eliminate the extra force. The compound control algorithm was verified through simulations and experiments. The results show that the tracking performance of the compound control algorithm satisfies the demands of engineering practice, and the extra force in the ELS system can be suppressed by the net torque corresponding to the actuator’s acceleration.
文摘In order to improve the impactor performance, the dynamic performance of gas-liquid united hydraulic hammer should be optimized. Based on the analysis of the operating principle for the hydraulic impactor, one simulation model of gas-liquid united hydraulic impactor was built with AMESim software. By setting different simulation parameters, curves of displacement, velocity, acceleration and cavity pressure were obtained under different working conditions. The key component can be obtained by the analysis of activity index. The whole simulation results provide a reliable basis for component selection and parameter optimization of hydraulic impactor.