Pub Date : 2020-01-01DOI: 10.1504/ijvsmt.2020.10034042
Zeng Kui
{"title":"A study on the enhancement of amplitude of DCT measured load spectrum considering time-frequency domain damage characteristics","authors":"Zeng Kui","doi":"10.1504/ijvsmt.2020.10034042","DOIUrl":"https://doi.org/10.1504/ijvsmt.2020.10034042","url":null,"abstract":"","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66698146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-01DOI: 10.1504/IJVSMT.2020.114981
M. Vignati, Sidharth Dave, F. Cheli
The addition of a trailer to a vehicle introduces significant changes to its dynamic behaviour. The lateral response of the system is of significant interest as unfavourable conditions may lead to instability in the system. The instability introduced may cause the vehicle to stray from the intended path, and in extreme situations may even cause the vehicle to topple over. This instability may be introduced by the driver or may even be triggered by external factors such as lateral forces arising because of wind. Active stabilisation systems are normally based on brakes. Electric vehicles with independent motors provide instead the opportunity to stabilise the system through torque vectoring. This paper proposes a feedback-loop control system as an active driver assistance system that enables stabilisation of the system by means of torque vectoring for an independent motor two-wheel drive electric vehicle.
{"title":"Active stabilisation of a car-trailer system by means of torque vectoring","authors":"M. Vignati, Sidharth Dave, F. Cheli","doi":"10.1504/IJVSMT.2020.114981","DOIUrl":"https://doi.org/10.1504/IJVSMT.2020.114981","url":null,"abstract":"The addition of a trailer to a vehicle introduces significant changes to its dynamic behaviour. The lateral response of the system is of significant interest as unfavourable conditions may lead to instability in the system. The instability introduced may cause the vehicle to stray from the intended path, and in extreme situations may even cause the vehicle to topple over. This instability may be introduced by the driver or may even be triggered by external factors such as lateral forces arising because of wind. Active stabilisation systems are normally based on brakes. Electric vehicles with independent motors provide instead the opportunity to stabilise the system through torque vectoring. This paper proposes a feedback-loop control system as an active driver assistance system that enables stabilisation of the system by means of torque vectoring for an independent motor two-wheel drive electric vehicle.","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66698270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-08DOI: 10.1504/IJVSMT.2019.10023128
A. Steinwolf, M. Wangenheim, J. Wallaschek
When analysing vehicle-road interaction, probability density function (PDF) of random micro-surface is required. Since the asperity tops are polished by tyres stronger than the valley bottoms, the surface height profiles become asymmetrical. As a result, the PDFs of micro-surface signals are often different from the Gaussian model and one needs a non-Gaussian PDF model operating with skewness and kurtosis. Previous solutions by the Pearson and Johnson distributions do not lend themselves for further implementation in analytical form. To overcome this difficulty, a non-Gaussian PDF can be constructed from a few Gaussian sections with different mean values and standard deviations. To use such a piecewise-Gaussian model for analytical derivations, it is simply necessary to apply the classic Gaussian equation several times. An example of skewed PDF of micro-surface of an asphaltic concrete highway measured by a laser scanning system was adequately approximated by the tetra-Gaussian model consisting of four Gaussian sections.
{"title":"On the use of non-Gaussian models for statistical description of road micro-surface profiles","authors":"A. Steinwolf, M. Wangenheim, J. Wallaschek","doi":"10.1504/IJVSMT.2019.10023128","DOIUrl":"https://doi.org/10.1504/IJVSMT.2019.10023128","url":null,"abstract":"When analysing vehicle-road interaction, probability density function (PDF) of random micro-surface is required. Since the asperity tops are polished by tyres stronger than the valley bottoms, the surface height profiles become asymmetrical. As a result, the PDFs of micro-surface signals are often different from the Gaussian model and one needs a non-Gaussian PDF model operating with skewness and kurtosis. Previous solutions by the Pearson and Johnson distributions do not lend themselves for further implementation in analytical form. To overcome this difficulty, a non-Gaussian PDF can be constructed from a few Gaussian sections with different mean values and standard deviations. To use such a piecewise-Gaussian model for analytical derivations, it is simply necessary to apply the classic Gaussian equation several times. An example of skewed PDF of micro-surface of an asphaltic concrete highway measured by a laser scanning system was adequately approximated by the tetra-Gaussian model consisting of four Gaussian sections.","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46258126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-08DOI: 10.1504/IJVSMT.2019.10023129
Zeinab El-Sayegh, M. El-Gindy, I. Johansson, F. Öijer
A rigid ring tyre model is developed using MATLAB/Simulink to predict the in-plane and out-of-plane rigid tyre model characteristics of a truck tyre running over different terrains. The in-plane and out-of-plane tyre characteristics include traction, cornering and vertical stiffness. The terrains used include hard surface, flooded surface, snow, and several soils such as dry and moist sand. The MATLAB/Simulink tyre model is validated against previously computed and published tyre-terrain interaction results performed using advanced simulations technique. The rigid ring tyre model is further implemented into a full vehicle model to evaluate the full vehicle response under several operating conditions.
{"title":"Development and validation of an off-road rigid ring truck tyre model","authors":"Zeinab El-Sayegh, M. El-Gindy, I. Johansson, F. Öijer","doi":"10.1504/IJVSMT.2019.10023129","DOIUrl":"https://doi.org/10.1504/IJVSMT.2019.10023129","url":null,"abstract":"A rigid ring tyre model is developed using MATLAB/Simulink to predict the in-plane and out-of-plane rigid tyre model characteristics of a truck tyre running over different terrains. The in-plane and out-of-plane tyre characteristics include traction, cornering and vertical stiffness. The terrains used include hard surface, flooded surface, snow, and several soils such as dry and moist sand. The MATLAB/Simulink tyre model is validated against previously computed and published tyre-terrain interaction results performed using advanced simulations technique. The rigid ring tyre model is further implemented into a full vehicle model to evaluate the full vehicle response under several operating conditions.","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46323046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-08DOI: 10.1504/IJVSMT.2019.10023126
Shaohua Wang, S. Zhang, D. Shi, Xiaoqiang Sun
Hybrid electric vehicles (HEVs) are now used more and more widely, especially the power split HEVs. However, the fuel consumption of HEVs varies with the configuration of the power coupling device. In this paper, a novel power coupling mechanism with dual planetary gear sets is proposed, which is developed from an automotive transmission in the conventional vehicle. By analysing its power split characteristics, it is proved that two brakes are essential to be added into the power coupling mechanism. The addition of brakes enriches operation modes, which is effective to improve the system efficiency, though it would increase the complexity of the system. Characteristic parameters of the planetary gear sets are optimised. For accurate evaluations of the proposed configuration, a global optimisation control strategy is established based on the dynamic programming (DP) algorithm. Simulation results under different driving cycles show that the fuel consumption of HEV with the proposed power coupling mechanism is 6.89% and 8.30% lower than that of a benchmark vehicle. The proposed power coupling mechanism proves to be beneficial to improve HEV fuel economy.
{"title":"Design and analysis of a coupling mechanism with dual planetary gear sets for the power split HEV","authors":"Shaohua Wang, S. Zhang, D. Shi, Xiaoqiang Sun","doi":"10.1504/IJVSMT.2019.10023126","DOIUrl":"https://doi.org/10.1504/IJVSMT.2019.10023126","url":null,"abstract":"Hybrid electric vehicles (HEVs) are now used more and more widely, especially the power split HEVs. However, the fuel consumption of HEVs varies with the configuration of the power coupling device. In this paper, a novel power coupling mechanism with dual planetary gear sets is proposed, which is developed from an automotive transmission in the conventional vehicle. By analysing its power split characteristics, it is proved that two brakes are essential to be added into the power coupling mechanism. The addition of brakes enriches operation modes, which is effective to improve the system efficiency, though it would increase the complexity of the system. Characteristic parameters of the planetary gear sets are optimised. For accurate evaluations of the proposed configuration, a global optimisation control strategy is established based on the dynamic programming (DP) algorithm. Simulation results under different driving cycles show that the fuel consumption of HEV with the proposed power coupling mechanism is 6.89% and 8.30% lower than that of a benchmark vehicle. The proposed power coupling mechanism proves to be beneficial to improve HEV fuel economy.","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43285057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-08DOI: 10.1504/IJVSMT.2019.10023125
Hongxun Fu, Fan Song, Kun Yang, Di Tan, Haitao Wang, Zhongyang Wang
The close integration of the in-wheel motor (IWM) driving system structure makes the space closed and narrow, and heat dissipation difficult. Meanwhile, the pursuit of high power density of the IWM leads to the increase of the loss density and the temperature of the IWM. This seriously affects the safe operation of the motor and the vehicle. In this paper, an interior permanent magnet synchronous IWM driving system is taken as the research object. The electromagnetic and temperature field analysis model are developed based on the detailed structure of the IWM driving system firstly. Then the transient thermal analysis under the rated and peak condition are carried out through the magneto-thermal coupling method. The results show that, under rated condition, when the IWM reaches a steady state, the highest temperature occurs on the copper wire of the stator winding, which is 111.8°C; under peak condition, due to the big loss generated by the motor overload operation, the maximum temperature of the motor reaches 170°C during the simulation analysis of 60 s, which has exceeded the motor insulation level requirements of 155°C. Therefore, cooling design is necessary in order to ensure the normal operation of the IWM and the vehicle.
{"title":"Transient thermal analysis of an interior permanent magnet synchronous in-wheel motor driving system","authors":"Hongxun Fu, Fan Song, Kun Yang, Di Tan, Haitao Wang, Zhongyang Wang","doi":"10.1504/IJVSMT.2019.10023125","DOIUrl":"https://doi.org/10.1504/IJVSMT.2019.10023125","url":null,"abstract":"The close integration of the in-wheel motor (IWM) driving system structure makes the space closed and narrow, and heat dissipation difficult. Meanwhile, the pursuit of high power density of the IWM leads to the increase of the loss density and the temperature of the IWM. This seriously affects the safe operation of the motor and the vehicle. In this paper, an interior permanent magnet synchronous IWM driving system is taken as the research object. The electromagnetic and temperature field analysis model are developed based on the detailed structure of the IWM driving system firstly. Then the transient thermal analysis under the rated and peak condition are carried out through the magneto-thermal coupling method. The results show that, under rated condition, when the IWM reaches a steady state, the highest temperature occurs on the copper wire of the stator winding, which is 111.8°C; under peak condition, due to the big loss generated by the motor overload operation, the maximum temperature of the motor reaches 170°C during the simulation analysis of 60 s, which has exceeded the motor insulation level requirements of 155°C. Therefore, cooling design is necessary in order to ensure the normal operation of the IWM and the vehicle.","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66698111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1504/ijvsmt.2019.10026623
Elias Dias Rossi Lopes, André Flora Alves Pinto, Moisés Xavier Guimarã, es Valentim, P. Peixoto, Ricardo Teixeira da Costa Neto
{"title":"Extended model for calculation of soil-wheel contact area parameters in rigid soil-deformable tyre approximation","authors":"Elias Dias Rossi Lopes, André Flora Alves Pinto, Moisés Xavier Guimarã, es Valentim, P. Peixoto, Ricardo Teixeira da Costa Neto","doi":"10.1504/ijvsmt.2019.10026623","DOIUrl":"https://doi.org/10.1504/ijvsmt.2019.10026623","url":null,"abstract":"","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66698165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1504/ijvsmt.2019.104877
T. Botha, P. S. Els
The location of a vehicle's centre of mass is an important parameter as it has a determining effect on the dynamics of a vehicle. The height of the vehicle centre of mass from the roll and pitch centres has a large influence on the load transfer which occurs between wheels during braking and cornering manoeuvres. These vehicle parameters can vary significantly especially on off-road vehicles due to the large differences in laden and unladen weight. This paper proposes an algorithm where suspension forces and inertial parameters are estimated in real time using inexpensive sensor measurements and an unscented Kalman filter. The algorithm is experimentally validated on an offroad vehicle performing various manoeuvres and driving over different terrains. The real time estimation of these parameters could contribute significantly to improving vehicle safety and control.
{"title":"Vehicle centre of mass, roll-centre and pitch-centre height estimation","authors":"T. Botha, P. S. Els","doi":"10.1504/ijvsmt.2019.104877","DOIUrl":"https://doi.org/10.1504/ijvsmt.2019.104877","url":null,"abstract":"The location of a vehicle's centre of mass is an important parameter as it has a determining effect on the dynamics of a vehicle. The height of the vehicle centre of mass from the roll and pitch centres has a large influence on the load transfer which occurs between wheels during braking and cornering manoeuvres. These vehicle parameters can vary significantly especially on off-road vehicles due to the large differences in laden and unladen weight. This paper proposes an algorithm where suspension forces and inertial parameters are estimated in real time using inexpensive sensor measurements and an unscented Kalman filter. The algorithm is experimentally validated on an offroad vehicle performing various manoeuvres and driving over different terrains. The real time estimation of these parameters could contribute significantly to improving vehicle safety and control.","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1504/ijvsmt.2019.104877","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66698230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1504/ijvsmt.2019.10026622
H. Ragheb, M. El-Gindy
Prodigious improvements have been attained in active vehicle safety systems region depending on different control systems. Active yaw control is one of these systems which target the vehicle stability in case of any rapid and/or severe manoeuvre. This paper presents the design of active yaw control system for (8 × 8) multi-wheeled vehicle and its integration with other safety control systems such as anti-lock braking system (ABS) and traction control system (TCS). A simplified vehicle model 'bicycle model' is employed to predict the desired vehicle yaw behaviour depending on road condition and driving situation. TruckSim-MATLAB/Simulink vehicle model was developed to verify the proposed integrated safety control system. The developed integrated active yaw controller with ABS and TCS succeeded in improving vehicle directional stability and traction performance. Furthermore, it should be mentioned that the road friction affects the controller efficiency as it limits the available braking torque to be used by the controller.
{"title":"Design of active yaw controller integrated with ABS and TCS for multi-wheeled vehicles","authors":"H. Ragheb, M. El-Gindy","doi":"10.1504/ijvsmt.2019.10026622","DOIUrl":"https://doi.org/10.1504/ijvsmt.2019.10026622","url":null,"abstract":"Prodigious improvements have been attained in active vehicle safety systems region depending on different control systems. Active yaw control is one of these systems which target the vehicle stability in case of any rapid and/or severe manoeuvre. This paper presents the design of active yaw control system for (8 × 8) multi-wheeled vehicle and its integration with other safety control systems such as anti-lock braking system (ABS) and traction control system (TCS). A simplified vehicle model 'bicycle model' is employed to predict the desired vehicle yaw behaviour depending on road condition and driving situation. TruckSim-MATLAB/Simulink vehicle model was developed to verify the proposed integrated safety control system. The developed integrated active yaw controller with ABS and TCS succeeded in improving vehicle directional stability and traction performance. Furthermore, it should be mentioned that the road friction affects the controller efficiency as it limits the available braking torque to be used by the controller.","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66698128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-01-01DOI: 10.1504/ijvsmt.2019.10026625
F. Abramchuk, A. Avramenko, A. Kuzmenko
Unsteady thermal loads on combustion chamber parts in a supercharged diesel engine dictate their service life. In practice, it is crucial to know the dynamic behaviour of temperatures and their gradients for automobile and tractor diesels that often change their operating conditions during running. Most reliable information can be obtained by experimental recording of temperatures on a test bench during engine tests. This information is used for mathematical modelling of temperature fields and temperature stresses. The objective of this research effort is the experimental recording of unsteady piston temperatures when the diesel load is increased and reduced rapidly. Thermocouples were chosen, and their thermal response was evaluated to increase the accuracy of recording piston temperatures. In addition, locations for installing thermocouples were chosen. A continuous-type current sensor was developed and refined to connect the hot junctions of the thermocouples with the recording instrumentation. The unsteady temperatures of the piston (aluminium alloy AL 25) in a high-speed diesel engine were recorded experimentally. Piston temperatures were recorded for cases when the load was increased and reduced rapidly. Treatment of experimental data has yielded the basic dynamic characteristics of the temperature fields in the diesel piston).
{"title":"Experimental recording of unsteady temperatures in the piston of a high-speed diesel engine under transient conditions","authors":"F. Abramchuk, A. Avramenko, A. Kuzmenko","doi":"10.1504/ijvsmt.2019.10026625","DOIUrl":"https://doi.org/10.1504/ijvsmt.2019.10026625","url":null,"abstract":"Unsteady thermal loads on combustion chamber parts in a supercharged diesel engine dictate their service life. In practice, it is crucial to know the dynamic behaviour of temperatures and their gradients for automobile and tractor diesels that often change their operating conditions during running. Most reliable information can be obtained by experimental recording of temperatures on a test bench during engine tests. This information is used for mathematical modelling of temperature fields and temperature stresses. The objective of this research effort is the experimental recording of unsteady piston temperatures when the diesel load is increased and reduced rapidly. Thermocouples were chosen, and their thermal response was evaluated to increase the accuracy of recording piston temperatures. In addition, locations for installing thermocouples were chosen. A continuous-type current sensor was developed and refined to connect the hot junctions of the thermocouples with the recording instrumentation. The unsteady temperatures of the piston (aluminium alloy AL 25) in a high-speed diesel engine were recorded experimentally. Piston temperatures were recorded for cases when the load was increased and reduced rapidly. Treatment of experimental data has yielded the basic dynamic characteristics of the temperature fields in the diesel piston).","PeriodicalId":35145,"journal":{"name":"International Journal of Vehicle Systems Modelling and Testing","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66698174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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