The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide.The electrical road system(ERS)can offer a viable solution for achieving zero CO_(2) emissions and has high energy effi...The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide.The electrical road system(ERS)can offer a viable solution for achieving zero CO_(2) emissions and has high energy efficiency in long-distance road cargo transport.While many kinds of pantograph structures have been developed for the ERS,their corresponding pantograph-catenary dynamic characteristics under different road conditions have not been investigated.This work performs a numerical study on the dynamics of the pantograph-catenary interaction of an ERS considering different pantograph structures.First,a pantograph-catenary-truck-road model is proposed.The reduced catenary model and reduced-plate model transmission method are used to minimize model scale.Three different types of ERS pantograph structures are considered in the model.After validation,the pantograph-catenary dynamics under the influence of truck-road interactions with complex road roughness and different pantographs are studied and compared.The corresponding vibration transmission mechanism is further focused.The results show that the truck-road interaction has a significant effect on the pantograph-catenary interaction,but the pantograph with only one lower and upper armcan isolate the roll vibrationmotion transmission fromthe truck to the collector head,which has the best dynamic performance and is suggested for use in the ERS.展开更多
The emission regulations for heavy-duty diesel engines regarding nitrogen oxide(NO_(x))are becoming increasingly stringent,particularly in relation to cold start cycles.While the twostage selective catalytic reduction...The emission regulations for heavy-duty diesel engines regarding nitrogen oxide(NO_(x))are becoming increasingly stringent,particularly in relation to cold start cycles.While the twostage selective catalytic reduction(SCR)has the potential to achieve ultra-low NO_(x) emissions,several challenges remain,including the accurate prediction of ammonia(NH_(3))storage mass and the co-control of the two-stage SCR.The first step in this study involved the establishment of a rapid control prototype platform to facilitate the development and validation of a two-stage SCR control strategy.Secondly,an initial method for predicting the NH_(3) storage based on the mass conservation law was proposed,which was subsequently improved by filling and emptying experiments.The third step involved the development of a two-stage SCR co-control strategy,including obtaining the steady-state NH_(3) storage target value,dynamic correction for NH_(3) storage target value,regulation of NH_(3) storage,and control of the close-coupled SCR urea injector state.Finally,the two-stage SCR urea injection control strategy was certified under the world harmonized transient cycle(WHTC).The results demonstrate that the composite value of engine outlet NO_(x) emissions under cold and hot start WHTC cycles is 13 g/(kW·h).Meanwhile,the composite value of tailpipe NO_(x) emissions under cold and hot start WHTC cycles is 0.065 g/(kW·h),representing only 14%of the EU VI limit value of 0.46 g/(kW·h).Thus,the findings demonstrate that integrating an accurate NH_(3) storage prediction method with the two-stage SCR co-control function is crucial for heavy-duty diesel engines to achieve ultra-low NO_(x) emissions.展开更多
Heavy-duty freight railway axles are no less important than those of passenger trains,owing to the potentially catastrophic results caused by the derailment of trains carrying hazardous substances.Intrinsic and extrin...Heavy-duty freight railway axles are no less important than those of passenger trains,owing to the potentially catastrophic results caused by the derailment of trains carrying hazardous substances.Intrinsic and extrinsic imperfections challenge classical design theories built based on the safe life concept,and damage tolerance assessment becomes vital for the safety and reliability of long-term serviced railway axles,as pits and scratches are common defects for heavy-duty railway axles.In this work,four-point rotating bending fatigue tests of AAR-CM railway axle steel specimens with semicircular and circumferential groove notches are conducted.The fatigue limit of the semicircular notched specimens was evaluated based on fracture mechanics theory,in which non-conservative results are obtained by the El Haddad model and the S–N curves of circumferential groove notched specimens are correlated by the theory of critical distance(TCD).展开更多
Multi-axle heavy-duty vehicles(MHVs)are essential for military equipment transport due to their safety and stability.However,braking dynamic responses between MHVs and pavement systems still remain underexplored,parti...Multi-axle heavy-duty vehicles(MHVs)are essential for military equipment transport due to their safety and stability.However,braking dynamic responses between MHVs and pavement systems still remain underexplored,particularly regarding their complex load transfer mechanisms.This paper develops an enhanced model of a multi-axle heavy-duty vehicle(MHV)coupled with the uneven and flexible pavement.An advanced coupling iterative method is proposed to solve the highly dimensional equations of the MHV-pavement coupled system.The proposed method was validated through experimental tests,with characteristic parameters of vertical accelerations showing relative errors between 0.42%and 11.80%.The coupling effect and influence mechanism of the braking process are investigated by characteristic parameters of the dynamic responses.Additionally,the influences of braking conditions and pavement parameters are analyzed in time and frequency domains in order to reveal the vibration mechanisms of the coupled system.Moreover,this study establishes a theoretical foundation for monitoring pavement health via vehicle-mounted acceleration signals,which is necessary in military transportation.展开更多
The emission of heavy-duty vehicles has raised great concerns worldwide.The complex working and loading conditions,which may differ a lot from PEMS tests,raised new challenges to the supervision and control of emissio...The emission of heavy-duty vehicles has raised great concerns worldwide.The complex working and loading conditions,which may differ a lot from PEMS tests,raised new challenges to the supervision and control of emissions,especially during real-world applications.On-board diagnostics(OBD)technology with data exchange enabled and strengthened the monitoring of emissions from a large number of heavy-duty diesel vehicles.This paper presents an analysis of the OBD data collected from more than 800 city and highway heavy-duty vehicles in China using remote OBD data terminals.Real-world NO_(x)and CO_(2)emissions of China-6 heavy-duty vehicles have been examined.The results showed that city heavy-duty vehicles had higher NO_(x)emission levels,which was mostly due to longer time of low SCR temperatures below 180°C.The application of novel methods based on 3BMAWalso found that heavy-duty diesel vehicles tended to have high NO_(x)emissions at idle.Also,little difference had been found in work-based CO_(2)emissions,and this may be due to no major difference were found in occupancies of hot running.展开更多
The accuracy of an articulated torque analysis influences the comprehensive performances of heavy-duty multi-legged robots. Currently, the extremal estimation method and some complex methods are employed to calculate ...The accuracy of an articulated torque analysis influences the comprehensive performances of heavy-duty multi-legged robots. Currently, the extremal estimation method and some complex methods are employed to calculate the articulated torques, which results in a large safety margin or a large number of calculations. To quickly obtain accurate articulated torques, an analysis method for the articulated torque is presented for an electrically driven heavy-duty six-legged robot. First, the rearmost leg that experiences the maximum normal contact force is confirmed when the robot transits a slope. Based on the ant-type and crab-type tripod gaits, the formulas of classical mechanics and MATLAB software are employed to theoretically analyze the relevant static torques of the joints. With the changes in the joint angles for the abductor joint, hip joint, and knee joint, variable tendency charts and extreme curves are obtained for the static articulated torques. Meanwhile, the maximum static articulated torques and the corresponding poses of the robot are also obtained. According to the poses of the robot under the maximum static articulated torques, ADAMS software is used to carry out a static simulation analysis. Based on the relevant simulation curves of the articulated torques, the maximum static articulated torques are acquired. A comparative analysis of the maximum static articulated torques shows that the theoretical calculation values are higher than the static simulation values, and the maximum error value is approximately 10%. The proposed method lays a foundation for quickly determining accurate articulated torques to develop heavy-duty six-legged robots.展开更多
Thermal error monitoring technology is the key technological support to solve the thermal error problem of heavy-duty CNC （computer numerical control） machine tools. Currently, there are many review literatures intr...Thermal error monitoring technology is the key technological support to solve the thermal error problem of heavy-duty CNC （computer numerical control） machine tools. Currently, there are many review literatures intro- ducing the thermal error research of CNC machine tools, but those mainly focus on the thermal issues in small and medium-sized CNC machine tools and seldom introduce thermal error monitoring technologies. This paper gives an overview of the research on the thermal error of CNC machine tools and emphasizes the study of thermal error of the heavy-duty CNC machine tool in three areas. These areas are the causes of thermal error of heavy-duty CNC machine tool and the issues with the temperature moni- toring technology and thermal deformation monitoring technology. A new optical measurement technology called the ＂fiber Bragg grating （FBG） distributed sensing tech- nology＂ for heavy-duty CNC machine tools is introduced in detail. This technology forms an intelligent sensing and monitoring system for heavy-duty CNC machine tools. This paper fills in the blank of this kind of review articlesto guide the development of this industry field and opens up new areas of research on the heavy-duty CNC machine tool thermal error.展开更多
In this work, some important factors such as ceramic shell strength, heat preservation temperature, standing time and withdrawal rate, which influence the formability of directionally solidified large-size blades of h...In this work, some important factors such as ceramic shell strength, heat preservation temperature, standing time and withdrawal rate, which influence the formability of directionally solidified large-size blades of heavy-duty gas turbine with the liquid metal cooling(LMC) process, were studied through the method of microstructure analysis combining. The results show that the ceramic shell with medium strength(the high temperature flexural strength is 8 MPa, the flexural strength after thermal shock resistance is 12 MPa and the residual flexural strength is 20 MPa) can prevent the rupture and runout of the blade. The appropriate temperature(1,520 ℃ for upper region and 1,500 ℃ for lower region) of the heating furnace can eliminate the wide-angle grain boundary, the deviation of grain and the run-out caused by the shell crack. The holding time after pouring(3-5 min) can promote the growth of competitive grains and avoid a great deviation of columnar grains along the crystal orientation <001>, resulting in a straight and uniform grain structure. In addition, to avoid the formation of wrinkles and to ensure a smooth blade surface, the withdrawal rate should be no greater than the growth rate of grain. It is also found that the dendritic space of the blade decreases with the rise of solidification rate, and increases with the enlarging distance between the solidification position and the chill plate.展开更多
When heavy-duty commercial vehicles(HDCVs)must engage in emergency braking,uncertain conditions such as the brake pressure and road profile variations will inevitably affect braking control.To minimize these uncertain...When heavy-duty commercial vehicles(HDCVs)must engage in emergency braking,uncertain conditions such as the brake pressure and road profile variations will inevitably affect braking control.To minimize these uncertainties,we propose a combined longitudinal and lateral controller method based on stochastic model predictive control(SMPC)that is achieved via Chebyshev–Cantelli inequality.In our method,SMPC calculates braking control inputs based on a finite time prediction that is achieved by solving stochastic programming elements,including chance constraints.To accomplish this,SMPC explicitly describes the probabilistic uncertainties to be used when designing a robust control strategy.The main contribution of this paper is the proposal of a braking control formulation that is robust against probabilistic friction circle uncertainty effects.More specifically,the use of Chebyshev–Cantelli inequality suppresses road profile influences,which have characteristics that are different from the Gaussian distribution,thereby improving both braking robustness and control performance against statistical disturbances.Additionally,since the Kalman filtering(KF)algorithm is used to obtain the expectation and covariance used for calculating deterministic transformed chance constraints,the SMPC is reformulated as a KF embedded deterministic MPC.Herein,the effectiveness of our proposed method is verified via a MATLAB/Simulink and TruckSim co-simulation.展开更多
This paper presents a comparative analysis of ground vibration in three directions generated by a heavy-duty railway with various track sections.The vibration characteristics in the plane area were investigated by usi...This paper presents a comparative analysis of ground vibration in three directions generated by a heavy-duty railway with various track sections.The vibration characteristics in the plane area were investigated by using matrix test measurements.Acceleration peak attenuation was faster within 25 m from the embankment,and the high-frequency vibration attenuates faster with increased distance.For the cutting section with multi-stage soil slope,decay rate of acceleration was relatively larger.The acceleration level of the plane region ranged to 82.2-89.1 dB by the single C80 train.Yet the acceleration level caused by the C80 trains running parallel after meeting showed a distinct increment.The increment of the cutting section was much larger compared with the embankment section,with the increment ranging from 1.2-2.5 dB.In terms of the cutting section,Y direction acceleration was dominant closer to the track.Within 10-30 m of the track,the Y direction acceleration(perpendicular to the rail)decreased rapidly and became comparable to the X direction(parallel to the rail)and Z direction.Additionally,the cutting case generated a higher level of vibration in all three directions compared to the embankment,but as the distance from track increased,the deviation between acceleration gradually decreased.展开更多
This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy...This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy-duty support node test. Test loads of the support reached 6 567 kN with multi-directional loading requirements, which outrange the capacity of the available loading devices. Through the reinforcement of a large-scale multi-directional inplane loading device, the innovative design of a self-balanced load transferring device, and other arrangement considerations of the loading system, the test was implemented and the loading capacity of the ring was considerably enlarged. Due to the heavy loading requirements, some checking computations of the ring and the load transferring device outranged the limit of the Chinese national code "Code for Design of Steel Structures (GB 50017—2003)", thus elastic-plastic finite element (FE) analysis was carried out on the two devices, and also the real-time monitoring on the whole loading systems during experiments to ensure test safety. FE analysis and test results show that the loading system worked elastically during experiments.展开更多
The electrically driven six-legged robot with high carrying capacity is an indispensable equipment for planetary exploration, but it hinders its practicability because of its low efficiency of carrying energy. Meanwhi...The electrically driven six-legged robot with high carrying capacity is an indispensable equipment for planetary exploration, but it hinders its practicability because of its low efficiency of carrying energy. Meanwhile, its load capacity also affects its application range. To reduce the power consumption, increase the load to mass ratio, and improve the stability of robot, the relationship between the walking modes and the forces of feet under the tripod gait are researched for an electrically driven heavy-duty six-legged robot. Based on the configuration characteristics of electrically driven heavy-duty six-legged, the typical walking modes of robot are analyzed. The mathematical models of the normal forces of feet are respectively established under the tripod gait of typical walking modes. According to the MATLAB software, the variable tendency charts are respectively gained for the normal forces of feet. The walking experiments under the typical tripod gaits are implemented for the prototype of electrically driven heavy-duty six-legged robot. The variable tendencies of maximum normal forces of feet are acquired. The comparison results show that the theoretical and experimental data are in the same trend. The walking modes which are most available to realize the average force of distribution of each foot are confirmed. The proposed method of analyzing the relationship between the walking modes and the forces of feet can quickly determine the optimal walking mode and gait parameters under the average distribution of foot force, which is propitious to develop the excellent heavy-duty multi-legged robots with the lower power consumption, larger load to mass ratio, and higher stability.展开更多
The lathes are basic machine tools for manufacturing cylindrical parts. In recent years, the DLseries computer numerical control(CNC) heavy-duty horizontal lathes(HDHLs) have been widely used in the transportation, en...The lathes are basic machine tools for manufacturing cylindrical parts. In recent years, the DLseries computer numerical control(CNC) heavy-duty horizontal lathes(HDHLs) have been widely used in the transportation, energy and aviation industries. High availability of the CNC heavy-duty lathes is demanded to guarantee the efficiency and benefit of these manufacturing industries. As one of the key subsystems of the HDHLs, the feeding control system is studied in this paper on reliability modeling and reliability analysis. The fault tree analysis(FTA) method is used for reliability modelling of the feeding control system. Considering the multiple common cause failure groups(CCFGs) existing in the system, a modified beta factor parametric model is introduced to model the common cause failure(CCF) in system. The reliability of feeding control system is then obtained and the effect of CCF on the reliability of the whole system is studied as well.展开更多
Fuel consumption is one of the main concerns for heavy-duty trucks.Predictive cruise control(PCC)provides an intriguing opportunity to reduce fuel consumption by using the upcoming road information.In this study,a rea...Fuel consumption is one of the main concerns for heavy-duty trucks.Predictive cruise control(PCC)provides an intriguing opportunity to reduce fuel consumption by using the upcoming road information.In this study,a real-time implementable PCC,which simultaneously optimizes engine torque and gear shifting,is proposed for heavy-duty trucks.To minimize fuel consumption,the problem of the PCC is formulated as a nonlinear model predictive control(MPC),in which the upcoming road elevation information is used.Finding the solution of the nonlinear MPC is time consuming;thus,a real-time implementable solver is developed based on Pontryagin’s maximum principle and indirect shooting method.Dynamic programming(DP)algorithm,as a global optimization algorithm,is used as a performance benchmark for the proposed solver.Simulation,hardware-in-the-loop and real-truck experiments are conducted to verify the performance of the proposed controller.The results demonstrate that the MPC-based solution performs nearly as well as the DP-based solution,with less than 1%deviation for testing roads.Moreover,the proposed co-optimization controller is implementable in a real-truck,and the proposed MPC-based PCC algorithm achieves a fuel-saving rate of 7.9%without compromising the truck’s travel time.展开更多
The reduction of fuel consumption in engines is always considered of vital importance.Along these lines,in this work,this goal was attained by optimizing the heavy-duty commercial vehicle engine control strategy.More ...The reduction of fuel consumption in engines is always considered of vital importance.Along these lines,in this work,this goal was attained by optimizing the heavy-duty commercial vehicle engine control strategy.More specifically,at first,a general first principles model for heavy-duty commercial vehicles and a transient fuel consumptionmodel for heavy-duty commercial vehicles were developed and the parameters were adjusted to fit the empirical data.The accuracy of the proposed modelwas demonstrated fromthe stage and the final results.Next,the control optimization problem resulting in low fuel consumption in heavy commercial vehicles was described,with minimal fuel usage as the optimization goal and throttle opening as the control variable.Then,a time-continuous engine management approach was assessed.Next,the factors that influence low fuel consumption in heavy-duty commercial vehicles were systematically examined.To reduce the computing complexity,the control strategies related to the time constraints of the engine were parametrized using three different methods.The most effective solution was obtained by applying a global optimization strategy because the constrained optimization problem was nonlinear.Finally,the effectiveness of the low-fuel consumption engine control strategy was demonstrated by comparing the simulated and field test results.展开更多
This paper presents the shear performance analysis of a heavy-duty universal hinged cast steel support with the largest bearing capacity. The effect of 9 parameters ( 52 specimens) ,i. e. height of the upper support,d...This paper presents the shear performance analysis of a heavy-duty universal hinged cast steel support with the largest bearing capacity. The effect of 9 parameters ( 52 specimens) ,i. e. height of the upper support,depth of the ring of the upper support,depth of the top plate of the bottom support,height of the ribs of the bottom support,depth of the ribs of the bottom support,bolt hole diameter,number of the ribs of the bowl,depth of the ribs of the bowl,and yield strength of the material,were analyzed with a 3-dimensional elastic-plastic finite element model in which the nonlinearities of geometry,material and contact were all considered. Analysis shows that height of the upper support,depth of the ring of the upper support and yield strength of the material have a great effect on the mechanical performance of the support. Height of the upper support has the largest effect on performance price ratio of the support,and the maximum effect can be up to 160% . Depth of the top plate of the bottom support,height of the ribs of the bottom support and depth of the ribs of the bottom support have a medium effect on performance price ratio of the support,and the effect is within the limit of 15% 19% .展开更多
At high altitudes, power of an internal combustion engine reduces due to air density reduction. In turbocharged diesel engine this issue affects the performance of the compressor and can result in unstable operation o...At high altitudes, power of an internal combustion engine reduces due to air density reduction. In turbocharged diesel engine this issue affects the performance of the compressor and can result in unstable operation of the turbocharger if the power is not decreased by engine actuator. Mainly for testing the effects of altitude in the test room, air throttle valve and combustion air handling unit were used to reduce the suction air pressure. Easier and cheaper solution to consider effect of altitude on engine performance is to mask part of the air filter to reduce the suction pressure. In this paper, pressure drop against 0%, 26%, 52%, 66% and 74% of air filter hole’s masking for different mass flow rates has been studied by computational fluid dynamics. The analysis output mass flow rate-pressure diagram for the air filter, will be used as input data in the GT-Power software which is a one-dimensional computational fluid dynamics software and the effect of masking on altitude and performance at different revolutions per minute of the engine is investigated. Also, an experimental and computational fluid dynamics study was carried out to predict altitude against different proportions of air filter hole’s masking at 1000 rpm. The predicted results are validated by comparing with those of experimental data. A good agreement between the predicted and experimental values ensures the accuracy of the numerical predictions with the present work.展开更多
The current research on the integrity of critical structures of rail vehicles mainly focuses on the design stage,which needs an effective method for assessing the service state.This paper proposes a framework for pred...The current research on the integrity of critical structures of rail vehicles mainly focuses on the design stage,which needs an effective method for assessing the service state.This paper proposes a framework for predicting the remaining useful life(RUL)of in-service structures with and without visible cracks.The hypothetical distribution and delay time models were used to apply the equivalent crack growth life data of heavy-duty railway cast steel knuckles,which revealed the evolution characteristics of the crack length and life scores of the knuckle under different fracture failure modes.The results indicate that the method effectively predicts the RUL of service knuckles in different failure modes based on the cumulative failure probability curves for different locations and surface crack lengths.This study proposes an RUL prediction framework that supports the dynamic overhaul and state maintenance of knuckle fatigue cracks.展开更多
The leg structure is crucial to the legged robot's motion performance.With the size and load of the legged robot increasing,the difficulty of leg design increases sharply.Inspired by biomechanics,this paper propos...The leg structure is crucial to the legged robot's motion performance.With the size and load of the legged robot increasing,the difficulty of leg design increases sharply.Inspired by biomechanics,this paper proposes a leg design approach based on effective mechanical advantage(EMA)for developing the heavy-duty legged robot.The bio-inspired design approach can reduce the demand for joint actuation forces during walking by optimizing the ratio relationship between the joint driving force and ground contact force.A dimensionless EMA model of the leg for the heavy-duty legged robot is constructed in this paper.Leg dimensions and hinge point locations are optimized according to the EMA and energy-optimal criterion.Based on the optimal leg structure,an electrically driven tri-segmented leg prototype is developed.The leg's joint hinge points are located near the main support line,and the load-to-weight ratio is 15:1.The leg can realize a swing frequency of 0.63 Hz at the stride length of 0.8 m,and the maximum stride length can reach 1.5 m.展开更多
In this study,a human-sensitive frequency band vibration isolator(HFBVI)with quasi-zero stiffness(QZS)characteristics for heavy-duty truck seats is designed to improve the comfort of heavy-duty truck drivers on uneven...In this study,a human-sensitive frequency band vibration isolator(HFBVI)with quasi-zero stiffness(QZS)characteristics for heavy-duty truck seats is designed to improve the comfort of heavy-duty truck drivers on uneven roads.First,the analytical expressions for the force and displacement of the HFBVI are derived with the Lagrange equation and d'Alembert's principle,and are validated through the prototype restoring force testing.Second,the harmonic balance method(HBM)is used to obtain the dynamic responses under harmonic excitation,and further the influence of pre-stretching on the dynamic characteristics and transmissibility is discussed.Finally,the experimental prototype of the HFBVI is fabricated,and vibration experiments are conducted under harmonic excitation to verify the vibration isolation performance(VIP)of the proposed vibration isolator.The experimental results indicate that the HFBVI can effectively suppress the frequency band(4-8 Hz)to which the human body is sensitive to vertical vibration.In addition,under real random road spectrum excitation,the HFBVI can achieve low-frequency vibration isolation close to 2 Hz,providing new prospects for ensuring the health of heavy-duty truck drivers.展开更多
基金supported by the National Natural Science Foundation of China(grant number 12302048,received by author Yan Xu)Yunnan fundamental research projects(grant No.202501AT070321,received by author Yan Xu).
文摘The emissions from traditional fossil heavy-duty trucks have become a conspicuous issue worldwide.The electrical road system(ERS)can offer a viable solution for achieving zero CO_(2) emissions and has high energy efficiency in long-distance road cargo transport.While many kinds of pantograph structures have been developed for the ERS,their corresponding pantograph-catenary dynamic characteristics under different road conditions have not been investigated.This work performs a numerical study on the dynamics of the pantograph-catenary interaction of an ERS considering different pantograph structures.First,a pantograph-catenary-truck-road model is proposed.The reduced catenary model and reduced-plate model transmission method are used to minimize model scale.Three different types of ERS pantograph structures are considered in the model.After validation,the pantograph-catenary dynamics under the influence of truck-road interactions with complex road roughness and different pantographs are studied and compared.The corresponding vibration transmission mechanism is further focused.The results show that the truck-road interaction has a significant effect on the pantograph-catenary interaction,but the pantograph with only one lower and upper armcan isolate the roll vibrationmotion transmission fromthe truck to the collector head,which has the best dynamic performance and is suggested for use in the ERS.
基金supported by the National Natural Science Foundation of China(No.51921004).
文摘The emission regulations for heavy-duty diesel engines regarding nitrogen oxide(NO_(x))are becoming increasingly stringent,particularly in relation to cold start cycles.While the twostage selective catalytic reduction(SCR)has the potential to achieve ultra-low NO_(x) emissions,several challenges remain,including the accurate prediction of ammonia(NH_(3))storage mass and the co-control of the two-stage SCR.The first step in this study involved the establishment of a rapid control prototype platform to facilitate the development and validation of a two-stage SCR control strategy.Secondly,an initial method for predicting the NH_(3) storage based on the mass conservation law was proposed,which was subsequently improved by filling and emptying experiments.The third step involved the development of a two-stage SCR co-control strategy,including obtaining the steady-state NH_(3) storage target value,dynamic correction for NH_(3) storage target value,regulation of NH_(3) storage,and control of the close-coupled SCR urea injector state.Finally,the two-stage SCR urea injection control strategy was certified under the world harmonized transient cycle(WHTC).The results demonstrate that the composite value of engine outlet NO_(x) emissions under cold and hot start WHTC cycles is 13 g/(kW·h).Meanwhile,the composite value of tailpipe NO_(x) emissions under cold and hot start WHTC cycles is 0.065 g/(kW·h),representing only 14%of the EU VI limit value of 0.46 g/(kW·h).Thus,the findings demonstrate that integrating an accurate NH_(3) storage prediction method with the two-stage SCR co-control function is crucial for heavy-duty diesel engines to achieve ultra-low NO_(x) emissions.
基金Supported by National Natural Science Foundation of China(Grant No.12232004)Guangdong Provincial Basic and Applied Basic Research Foundation(Grant No.2022A1515140111)+1 种基金Anhui Provincial Science and Technology Projects(Grant No.JB24075)Sichuan Provincial Science and Technology Program(Grant Nos.2024NSFSC2020,2023YFG0234)。
文摘Heavy-duty freight railway axles are no less important than those of passenger trains,owing to the potentially catastrophic results caused by the derailment of trains carrying hazardous substances.Intrinsic and extrinsic imperfections challenge classical design theories built based on the safe life concept,and damage tolerance assessment becomes vital for the safety and reliability of long-term serviced railway axles,as pits and scratches are common defects for heavy-duty railway axles.In this work,four-point rotating bending fatigue tests of AAR-CM railway axle steel specimens with semicircular and circumferential groove notches are conducted.The fatigue limit of the semicircular notched specimens was evaluated based on fracture mechanics theory,in which non-conservative results are obtained by the El Haddad model and the S–N curves of circumferential groove notched specimens are correlated by the theory of critical distance(TCD).
基金National Defense Basic Scientific Research Program of China(Grant No.JCKY2021602B030).
文摘Multi-axle heavy-duty vehicles(MHVs)are essential for military equipment transport due to their safety and stability.However,braking dynamic responses between MHVs and pavement systems still remain underexplored,particularly regarding their complex load transfer mechanisms.This paper develops an enhanced model of a multi-axle heavy-duty vehicle(MHV)coupled with the uneven and flexible pavement.An advanced coupling iterative method is proposed to solve the highly dimensional equations of the MHV-pavement coupled system.The proposed method was validated through experimental tests,with characteristic parameters of vertical accelerations showing relative errors between 0.42%and 11.80%.The coupling effect and influence mechanism of the braking process are investigated by characteristic parameters of the dynamic responses.Additionally,the influences of braking conditions and pavement parameters are analyzed in time and frequency domains in order to reveal the vibration mechanisms of the coupled system.Moreover,this study establishes a theoretical foundation for monitoring pavement health via vehicle-mounted acceleration signals,which is necessary in military transportation.
基金supported by the National Key Research and Development Project of China(No.2022YFC3701802)the National Natural Science Foundation of China(No.52272342)the Major Science and Technology Projects of Qinghai Province(No.2019-GX-A6).
文摘The emission of heavy-duty vehicles has raised great concerns worldwide.The complex working and loading conditions,which may differ a lot from PEMS tests,raised new challenges to the supervision and control of emissions,especially during real-world applications.On-board diagnostics(OBD)technology with data exchange enabled and strengthened the monitoring of emissions from a large number of heavy-duty diesel vehicles.This paper presents an analysis of the OBD data collected from more than 800 city and highway heavy-duty vehicles in China using remote OBD data terminals.Real-world NO_(x)and CO_(2)emissions of China-6 heavy-duty vehicles have been examined.The results showed that city heavy-duty vehicles had higher NO_(x)emission levels,which was mostly due to longer time of low SCR temperatures below 180°C.The application of novel methods based on 3BMAWalso found that heavy-duty diesel vehicles tended to have high NO_(x)emissions at idle.Also,little difference had been found in work-based CO_(2)emissions,and this may be due to no major difference were found in occupancies of hot running.
基金supported by National Basic Research Program of China(973 Program, Grant No. 2013CB035502)International Science and Technology Cooperation Project with Russia (Grant No. 2010DFR70270)+2 种基金National Natural Science Foundation of China (Grant No. 51275106)"111" Project (Grant No. B07018)Key Laboratory Opening Funding of Aerospace Mechanism and Control, China (Grant No. HIT. KLOF.2010057)
文摘The accuracy of an articulated torque analysis influences the comprehensive performances of heavy-duty multi-legged robots. Currently, the extremal estimation method and some complex methods are employed to calculate the articulated torques, which results in a large safety margin or a large number of calculations. To quickly obtain accurate articulated torques, an analysis method for the articulated torque is presented for an electrically driven heavy-duty six-legged robot. First, the rearmost leg that experiences the maximum normal contact force is confirmed when the robot transits a slope. Based on the ant-type and crab-type tripod gaits, the formulas of classical mechanics and MATLAB software are employed to theoretically analyze the relevant static torques of the joints. With the changes in the joint angles for the abductor joint, hip joint, and knee joint, variable tendency charts and extreme curves are obtained for the static articulated torques. Meanwhile, the maximum static articulated torques and the corresponding poses of the robot are also obtained. According to the poses of the robot under the maximum static articulated torques, ADAMS software is used to carry out a static simulation analysis. Based on the relevant simulation curves of the articulated torques, the maximum static articulated torques are acquired. A comparative analysis of the maximum static articulated torques shows that the theoretical calculation values are higher than the static simulation values, and the maximum error value is approximately 10%. The proposed method lays a foundation for quickly determining accurate articulated torques to develop heavy-duty six-legged robots.
基金Supported by National Natural Science Foundation of China(Grant No.51475343)International Science and Technology Cooperation Program of China(Grant No.2015DFA70340)
文摘Thermal error monitoring technology is the key technological support to solve the thermal error problem of heavy-duty CNC （computer numerical control） machine tools. Currently, there are many review literatures intro- ducing the thermal error research of CNC machine tools, but those mainly focus on the thermal issues in small and medium-sized CNC machine tools and seldom introduce thermal error monitoring technologies. This paper gives an overview of the research on the thermal error of CNC machine tools and emphasizes the study of thermal error of the heavy-duty CNC machine tool in three areas. These areas are the causes of thermal error of heavy-duty CNC machine tool and the issues with the temperature moni- toring technology and thermal deformation monitoring technology. A new optical measurement technology called the ＂fiber Bragg grating （FBG） distributed sensing tech- nology＂ for heavy-duty CNC machine tools is introduced in detail. This technology forms an intelligent sensing and monitoring system for heavy-duty CNC machine tools. This paper fills in the blank of this kind of review articlesto guide the development of this industry field and opens up new areas of research on the heavy-duty CNC machine tool thermal error.
基金financially supported by the National Science and Technology Major Project of High-end CNC Machine Tools and Basic Manufacturing Equipment(No.2017ZX04014001)
文摘In this work, some important factors such as ceramic shell strength, heat preservation temperature, standing time and withdrawal rate, which influence the formability of directionally solidified large-size blades of heavy-duty gas turbine with the liquid metal cooling(LMC) process, were studied through the method of microstructure analysis combining. The results show that the ceramic shell with medium strength(the high temperature flexural strength is 8 MPa, the flexural strength after thermal shock resistance is 12 MPa and the residual flexural strength is 20 MPa) can prevent the rupture and runout of the blade. The appropriate temperature(1,520 ℃ for upper region and 1,500 ℃ for lower region) of the heating furnace can eliminate the wide-angle grain boundary, the deviation of grain and the run-out caused by the shell crack. The holding time after pouring(3-5 min) can promote the growth of competitive grains and avoid a great deviation of columnar grains along the crystal orientation <001>, resulting in a straight and uniform grain structure. In addition, to avoid the formation of wrinkles and to ensure a smooth blade surface, the withdrawal rate should be no greater than the growth rate of grain. It is also found that the dendritic space of the blade decreases with the rise of solidification rate, and increases with the enlarging distance between the solidification position and the chill plate.
文摘When heavy-duty commercial vehicles(HDCVs)must engage in emergency braking,uncertain conditions such as the brake pressure and road profile variations will inevitably affect braking control.To minimize these uncertainties,we propose a combined longitudinal and lateral controller method based on stochastic model predictive control(SMPC)that is achieved via Chebyshev–Cantelli inequality.In our method,SMPC calculates braking control inputs based on a finite time prediction that is achieved by solving stochastic programming elements,including chance constraints.To accomplish this,SMPC explicitly describes the probabilistic uncertainties to be used when designing a robust control strategy.The main contribution of this paper is the proposal of a braking control formulation that is robust against probabilistic friction circle uncertainty effects.More specifically,the use of Chebyshev–Cantelli inequality suppresses road profile influences,which have characteristics that are different from the Gaussian distribution,thereby improving both braking robustness and control performance against statistical disturbances.Additionally,since the Kalman filtering(KF)algorithm is used to obtain the expectation and covariance used for calculating deterministic transformed chance constraints,the SMPC is reformulated as a KF embedded deterministic MPC.Herein,the effectiveness of our proposed method is verified via a MATLAB/Simulink and TruckSim co-simulation.
基金Natural Science Foundation of China under Grant No.51878242Hebei Natural Science Foundation of China under Grant Nos.E2017404013 and E2020404007。
文摘This paper presents a comparative analysis of ground vibration in three directions generated by a heavy-duty railway with various track sections.The vibration characteristics in the plane area were investigated by using matrix test measurements.Acceleration peak attenuation was faster within 25 m from the embankment,and the high-frequency vibration attenuates faster with increased distance.For the cutting section with multi-stage soil slope,decay rate of acceleration was relatively larger.The acceleration level of the plane region ranged to 82.2-89.1 dB by the single C80 train.Yet the acceleration level caused by the C80 trains running parallel after meeting showed a distinct increment.The increment of the cutting section was much larger compared with the embankment section,with the increment ranging from 1.2-2.5 dB.In terms of the cutting section,Y direction acceleration was dominant closer to the track.Within 10-30 m of the track,the Y direction acceleration(perpendicular to the rail)decreased rapidly and became comparable to the X direction(parallel to the rail)and Z direction.Additionally,the cutting case generated a higher level of vibration in all three directions compared to the embankment,but as the distance from track increased,the deviation between acceleration gradually decreased.
基金Supported by National Natural Science Foundation of China (No. 50878066)the National Key Technology R&D Program in the 11th Five-Year Plan of China (No. 2006BAJ01B02)the Key Technologies R&D Program of Heilongjiang Province, China (No. GB02C204)
文摘This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy-duty support node test. Test loads of the support reached 6 567 kN with multi-directional loading requirements, which outrange the capacity of the available loading devices. Through the reinforcement of a large-scale multi-directional inplane loading device, the innovative design of a self-balanced load transferring device, and other arrangement considerations of the loading system, the test was implemented and the loading capacity of the ring was considerably enlarged. Due to the heavy loading requirements, some checking computations of the ring and the load transferring device outranged the limit of the Chinese national code "Code for Design of Steel Structures (GB 50017—2003)", thus elastic-plastic finite element (FE) analysis was carried out on the two devices, and also the real-time monitoring on the whole loading systems during experiments to ensure test safety. FE analysis and test results show that the loading system worked elastically during experiments.
基金Supported by National Natural Science Foundation of China(Grant Nos.51505335,51275106)National Basic Research Program of China(973Program,Grant No.2013CB035502)
文摘The electrically driven six-legged robot with high carrying capacity is an indispensable equipment for planetary exploration, but it hinders its practicability because of its low efficiency of carrying energy. Meanwhile, its load capacity also affects its application range. To reduce the power consumption, increase the load to mass ratio, and improve the stability of robot, the relationship between the walking modes and the forces of feet under the tripod gait are researched for an electrically driven heavy-duty six-legged robot. Based on the configuration characteristics of electrically driven heavy-duty six-legged, the typical walking modes of robot are analyzed. The mathematical models of the normal forces of feet are respectively established under the tripod gait of typical walking modes. According to the MATLAB software, the variable tendency charts are respectively gained for the normal forces of feet. The walking experiments under the typical tripod gaits are implemented for the prototype of electrically driven heavy-duty six-legged robot. The variable tendencies of maximum normal forces of feet are acquired. The comparison results show that the theoretical and experimental data are in the same trend. The walking modes which are most available to realize the average force of distribution of each foot are confirmed. The proposed method of analyzing the relationship between the walking modes and the forces of feet can quickly determine the optimal walking mode and gait parameters under the average distribution of foot force, which is propitious to develop the excellent heavy-duty multi-legged robots with the lower power consumption, larger load to mass ratio, and higher stability.
基金the National Science and Technology Major Project of China(No.2014ZX04014-011)
文摘The lathes are basic machine tools for manufacturing cylindrical parts. In recent years, the DLseries computer numerical control(CNC) heavy-duty horizontal lathes(HDHLs) have been widely used in the transportation, energy and aviation industries. High availability of the CNC heavy-duty lathes is demanded to guarantee the efficiency and benefit of these manufacturing industries. As one of the key subsystems of the HDHLs, the feeding control system is studied in this paper on reliability modeling and reliability analysis. The fault tree analysis(FTA) method is used for reliability modelling of the feeding control system. Considering the multiple common cause failure groups(CCFGs) existing in the system, a modified beta factor parametric model is introduced to model the common cause failure(CCF) in system. The reliability of feeding control system is then obtained and the effect of CCF on the reliability of the whole system is studied as well.
基金Supported by International Technology Cooperation Program of Science and Technology Commission of Shanghai Municipality of China(Grant No.21160710600)National Nature Science Foundation of China(Grant No.52372393)Shanghai Pujiang Program of China(Grant No.21PJD075).
文摘Fuel consumption is one of the main concerns for heavy-duty trucks.Predictive cruise control(PCC)provides an intriguing opportunity to reduce fuel consumption by using the upcoming road information.In this study,a real-time implementable PCC,which simultaneously optimizes engine torque and gear shifting,is proposed for heavy-duty trucks.To minimize fuel consumption,the problem of the PCC is formulated as a nonlinear model predictive control(MPC),in which the upcoming road elevation information is used.Finding the solution of the nonlinear MPC is time consuming;thus,a real-time implementable solver is developed based on Pontryagin’s maximum principle and indirect shooting method.Dynamic programming(DP)algorithm,as a global optimization algorithm,is used as a performance benchmark for the proposed solver.Simulation,hardware-in-the-loop and real-truck experiments are conducted to verify the performance of the proposed controller.The results demonstrate that the MPC-based solution performs nearly as well as the DP-based solution,with less than 1%deviation for testing roads.Moreover,the proposed co-optimization controller is implementable in a real-truck,and the proposed MPC-based PCC algorithm achieves a fuel-saving rate of 7.9%without compromising the truck’s travel time.
基金This work was supported in part by the Science and Technology Major Project of Guangxi under Grant AA22068001in part by the Key Research and Development Program of Guangxi AB21196029+3 种基金in part by the Project of National Natural Science Foundation of China 51965012in part by the Scientific Research and TechnologyDevelopment in Liuzhou 2022AAA0102,2021AAA0104 and 2021AAA0112in part by Agricultural Science and Technology Innovation and Extension Special Project of Jiangsu Province NJ2021-21,in part by the Guangxi Key Laboratory of Manufacturing System and Advanced Manufacturing Technology,in part by the Guilin University of Electronic Technology 20-065-40-004Zin part by the Innovation Project of GUET Graduate Education 2022YCXS017.
文摘The reduction of fuel consumption in engines is always considered of vital importance.Along these lines,in this work,this goal was attained by optimizing the heavy-duty commercial vehicle engine control strategy.More specifically,at first,a general first principles model for heavy-duty commercial vehicles and a transient fuel consumptionmodel for heavy-duty commercial vehicles were developed and the parameters were adjusted to fit the empirical data.The accuracy of the proposed modelwas demonstrated fromthe stage and the final results.Next,the control optimization problem resulting in low fuel consumption in heavy commercial vehicles was described,with minimal fuel usage as the optimization goal and throttle opening as the control variable.Then,a time-continuous engine management approach was assessed.Next,the factors that influence low fuel consumption in heavy-duty commercial vehicles were systematically examined.To reduce the computing complexity,the control strategies related to the time constraints of the engine were parametrized using three different methods.The most effective solution was obtained by applying a global optimization strategy because the constrained optimization problem was nonlinear.Finally,the effectiveness of the low-fuel consumption engine control strategy was demonstrated by comparing the simulated and field test results.
基金Sponsored by the National Natural Science Foundation of China( Grant No. 50878066)the National Key Technology R&D Program during the 11th Five-Year Plan Period of China( Grant No. 2006BAJ01B02)
文摘This paper presents the shear performance analysis of a heavy-duty universal hinged cast steel support with the largest bearing capacity. The effect of 9 parameters ( 52 specimens) ,i. e. height of the upper support,depth of the ring of the upper support,depth of the top plate of the bottom support,height of the ribs of the bottom support,depth of the ribs of the bottom support,bolt hole diameter,number of the ribs of the bowl,depth of the ribs of the bowl,and yield strength of the material,were analyzed with a 3-dimensional elastic-plastic finite element model in which the nonlinearities of geometry,material and contact were all considered. Analysis shows that height of the upper support,depth of the ring of the upper support and yield strength of the material have a great effect on the mechanical performance of the support. Height of the upper support has the largest effect on performance price ratio of the support,and the maximum effect can be up to 160% . Depth of the top plate of the bottom support,height of the ribs of the bottom support and depth of the ribs of the bottom support have a medium effect on performance price ratio of the support,and the effect is within the limit of 15% 19% .
文摘At high altitudes, power of an internal combustion engine reduces due to air density reduction. In turbocharged diesel engine this issue affects the performance of the compressor and can result in unstable operation of the turbocharger if the power is not decreased by engine actuator. Mainly for testing the effects of altitude in the test room, air throttle valve and combustion air handling unit were used to reduce the suction air pressure. Easier and cheaper solution to consider effect of altitude on engine performance is to mask part of the air filter to reduce the suction pressure. In this paper, pressure drop against 0%, 26%, 52%, 66% and 74% of air filter hole’s masking for different mass flow rates has been studied by computational fluid dynamics. The analysis output mass flow rate-pressure diagram for the air filter, will be used as input data in the GT-Power software which is a one-dimensional computational fluid dynamics software and the effect of masking on altitude and performance at different revolutions per minute of the engine is investigated. Also, an experimental and computational fluid dynamics study was carried out to predict altitude against different proportions of air filter hole’s masking at 1000 rpm. The predicted results are validated by comparing with those of experimental data. A good agreement between the predicted and experimental values ensures the accuracy of the numerical predictions with the present work.
基金Supported by National Natural Science Foundation of China (Grant No.52175123)Sichuan Provincial Outstanding Youth Fund (Grant No.22JDJQ0025)Independent Exploration Project of State Key Laboratory of Railway Transit Vehicle System (Grant No.2024RVL-T03)。
文摘The current research on the integrity of critical structures of rail vehicles mainly focuses on the design stage,which needs an effective method for assessing the service state.This paper proposes a framework for predicting the remaining useful life(RUL)of in-service structures with and without visible cracks.The hypothetical distribution and delay time models were used to apply the equivalent crack growth life data of heavy-duty railway cast steel knuckles,which revealed the evolution characteristics of the crack length and life scores of the knuckle under different fracture failure modes.The results indicate that the method effectively predicts the RUL of service knuckles in different failure modes based on the cumulative failure probability curves for different locations and surface crack lengths.This study proposes an RUL prediction framework that supports the dynamic overhaul and state maintenance of knuckle fatigue cracks.
基金supported in part by the National Key R&D Program of China under Grant No.2019YFB1309502in part by the project under Grant No.2019ZT08Z780.
文摘The leg structure is crucial to the legged robot's motion performance.With the size and load of the legged robot increasing,the difficulty of leg design increases sharply.Inspired by biomechanics,this paper proposes a leg design approach based on effective mechanical advantage(EMA)for developing the heavy-duty legged robot.The bio-inspired design approach can reduce the demand for joint actuation forces during walking by optimizing the ratio relationship between the joint driving force and ground contact force.A dimensionless EMA model of the leg for the heavy-duty legged robot is constructed in this paper.Leg dimensions and hinge point locations are optimized according to the EMA and energy-optimal criterion.Based on the optimal leg structure,an electrically driven tri-segmented leg prototype is developed.The leg's joint hinge points are located near the main support line,and the load-to-weight ratio is 15:1.The leg can realize a swing frequency of 0.63 Hz at the stride length of 0.8 m,and the maximum stride length can reach 1.5 m.
基金supported by the National Natural Science Foundation of China(No.12172226)。
文摘In this study,a human-sensitive frequency band vibration isolator(HFBVI)with quasi-zero stiffness(QZS)characteristics for heavy-duty truck seats is designed to improve the comfort of heavy-duty truck drivers on uneven roads.First,the analytical expressions for the force and displacement of the HFBVI are derived with the Lagrange equation and d'Alembert's principle,and are validated through the prototype restoring force testing.Second,the harmonic balance method(HBM)is used to obtain the dynamic responses under harmonic excitation,and further the influence of pre-stretching on the dynamic characteristics and transmissibility is discussed.Finally,the experimental prototype of the HFBVI is fabricated,and vibration experiments are conducted under harmonic excitation to verify the vibration isolation performance(VIP)of the proposed vibration isolator.The experimental results indicate that the HFBVI can effectively suppress the frequency band(4-8 Hz)to which the human body is sensitive to vertical vibration.In addition,under real random road spectrum excitation,the HFBVI can achieve low-frequency vibration isolation close to 2 Hz,providing new prospects for ensuring the health of heavy-duty truck drivers.
