Collision avoidance decision-making models of multiple agents in virtual driving environment are studied. Based on the behavioral characteristics and hierarchical structure of the collision avoidance decision-making i...Collision avoidance decision-making models of multiple agents in virtual driving environment are studied. Based on the behavioral characteristics and hierarchical structure of the collision avoidance decision-making in real life driving, delphi approach and mathematical statistics method are introduced to construct pair-wise comparison judgment matrix of collision avoidance decision choices to each collision situation. Analytic hierarchy process （AHP） is adopted to establish the agents＇ collision avoidance decision-making model. To simulate drivers＇ characteristics, driver factors are added to categorize driving modes into impatient mode, normal mode, and the cautious mode. The results show that this model can simulate human＇s thinking process, and the agents in the virtual environment can deal with collision situations and make decisions to avoid collisions without intervention. The model can also reflect diversity and uncertainly of real life driving behaviors, and solves the multi-objective, multi-choice ranking priority problem in multi-vehicle collision scenarios. This collision avoidance model of multi-agents model is feasible and effective, and can provide richer and closer-to-life virtual scene for driving simulator, reflecting real-life traffic environment more truly, this model can also promote the practicality of driving simulator.展开更多
The pace and scale of China＇s contemporary urbanization are stunning. This paper reviews process and the underlying driving forces of China＇s urbanization between 1949-2015. Contemporary China＇s urbanization has ex...The pace and scale of China＇s contemporary urbanization are stunning. This paper reviews process and the underlying driving forces of China＇s urbanization between 1949-2015. Contemporary China＇s urbanization has experienced four stages, and each has had different driving forces： 1） economic re-construction and industrialization-led urbanization 0949-1977）; 2） economic reform and mar- ket-led urbanization （1978-1995）; 3） economic globalization and the global-local urbanization （1996-2010）; and 4） the land-economy- led urbanization （2010-）. These urbanization processes and driving forces will undoubtedly provide scientific reference and have sig- nificant implications for developing countries, especially African countries, to formulate their urbanization public policies.展开更多
Based on the long-term serial NOAA/NDVI dataset during 1983-1999 and SPOT/VGT dataset in 2001, the land use/cover change information in the 13 provinces of northern China was extracted based on the analysis of the cul...Based on the long-term serial NOAA/NDVI dataset during 1983-1999 and SPOT/VGT dataset in 2001, the land use/cover change information in the 13 provinces of northern China was extracted based on the analysis of the cultivated landscape characteristics at first, then the effects of human activities on cultivated land process were explored by GIS and the driving forces of cultivated land change were investigated. The conclusions can be drawn as follows： （1） The constant increase of weak ecological function land as desert and cultivated land and the decrease of the ecological function land of forest and shrub were the main characteristics of the land use/cover change in the 13 provinces from 1983 to 1999, which showed the effects on the ecological adjustment fimction. However, such situations were changed to some extent in the 2000s because of the eco-construction policy of the government. （2） From 1983 to 2001, the Barycenter of cultivated land tended to move from northeast to southwest with the topography and transportation situations being the main influences on the cultivated land distribution. It is found that the cultivated land use intensity decreased noticably with the increase of distance from the main communication arteries. （3） The improvement of the people＇s living standard is closely related with the cultivated land change. The structural adjustment in the agricultural land caused by economic development and the improvement of the people＇s living standard ig an important factor affecting the cultivated land change in northern China from 1983 to 2001展开更多
Cooperative driving around intersections has aroused increasing interest in the last five years.Meanwhile,driving safety in non-signalized intersections has become an issue that has attracted attention globally.In vie...Cooperative driving around intersections has aroused increasing interest in the last five years.Meanwhile,driving safety in non-signalized intersections has become an issue that has attracted attention globally.In view of the potential collision risk when more than three vehicles approach a non-signalized intersection from different directions,we propose a driving model using cooperative game theory.First,the characteristic functions of this model are primarily established on each vehicle’s profit function and include safety,rapidity and comfort indicators.Second,the Shapley theorem is adopted,and its group rationality,individual rationality,and uniqueness are proved to be suitable for the characteristic functions of the model.Following this,different drivers’characteristics are considered.In order to simplify the calculation process,a zero-mean normalization method is introduced.In addition,a genetic algorithm method is adopted to search an optimal strategy set in the constrained multi-objective optimization problem.Finally,the model is confirmed as valid after simulation with a series of initial conditions.展开更多
In mixed and dynamic traffic environments,accurate long-term trajectory forecasting of surrounding vehicles is one of the indispensable preconditions for autonomous vehicles to accomplish reasonable behavioral decisio...In mixed and dynamic traffic environments,accurate long-term trajectory forecasting of surrounding vehicles is one of the indispensable preconditions for autonomous vehicles to accomplish reasonable behavioral decisions and guarantee driving safety.In this paper,we propose an integrated probabilistic architecture for long-term vehicle trajectory prediction,which consists of a driving inference model(DIM)and a trajectory prediction model(TPM).The DIM is designed and employed to accurately infer the potential driving intention based on a dynamic Bayesian network.The proposed DIM incorporates the basic traffic rules and multivariate vehicle motion information.To further improve the prediction accuracy and realize uncertainty estimation,we develop a Gaussian process-based TPM,considering both the short-term prediction results of the vehicle model and the driving motion characteristics.Afterward,the effectiveness of our novel approach is demonstrated by conducting experiments on a public naturalistic driving dataset under lane-changing scenarios.The superior performance on the task of long-term trajectory prediction is presented and verified by comparing with other advanced methods.展开更多
The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming(ISF)in industrial field.As a novel approach,the interpolator method is a promising strategy to enhance the surface qu...The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming(ISF)in industrial field.As a novel approach,the interpolator method is a promising strategy to enhance the surface quality in ISF.However,the mechanism for the improvement of surface quality and the influence of interpolator properties on surface roughness are not well understood.In this paper,the influences of process variables(i.e.tool diameter,step size and thickness of interpolators)on the forming process(e.g.surface roughness,forming force and geometric error)are investigated through a systematic experimental approach of central composite design(CCD)in two-point incremental sheet forming(TPIF).It is obtained that the increase in thickness of interpolators decreases the surface roughness in direction vertical to the tool path while increases the surface roughness in direction horizontal to the tool path.Nevertheless,the combined influence between thickness of interpolators and process parameters(tool diameter and step size)is limited.Meanwhile,the placement of interpolator has little influence on the effective forming force of blank.In addition,the geometric error enlarges with the increase of step size and thickness of interpolator while decreases firstly and then increase with an increase in tool diameter.Finally,the influencing mechanism of the interpolator method on surface quality can be attributed to the decrease of thecontact pressure due to the increase of contact area with the unchanged contact force.Meanwhile,the interpolator method eliminates the sliding friction on the surface of blank due to the stable relative position between the blank and the interpolator.展开更多
The studies of driving forces of regional land use change(LUC)are to reveal the real motivation behind the LUC and its interacting mechanism,so as to simulate and predict the process of LUC.Presently,studies rooting f...The studies of driving forces of regional land use change(LUC)are to reveal the real motivation behind the LUC and its interacting mechanism,so as to simulate and predict the process of LUC.Presently,studies rooting from different natural and socio-economic backgrounds and from different scales have deepened the people’s understanding and cognition to driving forces of regional LUC.Biophysical driving forces are relatively stable,and have the cumulating effects.Human driving forces are relatively active,and are main driving forces of short-term regional LUC.Existing regional LUC models can answer the three main problems:which contribution(why),which location(where)and what rate(when).But,regional land use system is defined as the self-organized system,usually affected by the cri-tical value area and sudden change,and controlled by different stages.To reduce the impact of critical threshold and break on land use system,the studies of LUC driving forces will aim at following priority areas:data linkage between remote sensing and no-remote sensing data;underlying driving force identification;driving factor quantification;driving factor scale dependence;and driving process integration simulation.展开更多
To prevent and reduce road traffic accidents and improve driver safety awareness and bad driving be-haviors,we propose a safety evaluation method for commercial vehicle driving behavior.Three driving style clas-sifica...To prevent and reduce road traffic accidents and improve driver safety awareness and bad driving be-haviors,we propose a safety evaluation method for commercial vehicle driving behavior.Three driving style clas-sification indexes were extracted using driving data from commercial vehicles and four primary and ten secondary safety evaluation indicators.Based on the stability of commercial vehicles transporting goods,the acceleration index is divided into three levels according to the statistical third quartile,and the evaluation expression of the safety index evaluation is established.Drivers were divided into conservative,moderate,and radical using K-means++.The weights corresponding to each index were calculated using a combination of the analytic hierarchy process(AHP)and criteria importance through intercriteria correlation(CRITIC),and the driving behavior scores of various drivers were calculated according to the safety index score standard.The established AHP-CRITIC safety evaluation model was verified using the actual driving behavior data of commercial vehicle drivers.The calculation results show that the proposed evaluation model can clearly distinguish between the types of drivers with different driving styles,verifying its rationality and validity.The evaluation results can provide a reference for transportation management departments and enterprises.展开更多
基金supported by National Basic Research Program (973 Program,No.2004CB719402)National Natural Science Foundation of China (No.60736019)Natural Science Foundation of Zhejiang Province, China(No.Y105430).
文摘Collision avoidance decision-making models of multiple agents in virtual driving environment are studied. Based on the behavioral characteristics and hierarchical structure of the collision avoidance decision-making in real life driving, delphi approach and mathematical statistics method are introduced to construct pair-wise comparison judgment matrix of collision avoidance decision choices to each collision situation. Analytic hierarchy process （AHP） is adopted to establish the agents＇ collision avoidance decision-making model. To simulate drivers＇ characteristics, driver factors are added to categorize driving modes into impatient mode, normal mode, and the cautious mode. The results show that this model can simulate human＇s thinking process, and the agents in the virtual environment can deal with collision situations and make decisions to avoid collisions without intervention. The model can also reflect diversity and uncertainly of real life driving behaviors, and solves the multi-objective, multi-choice ranking priority problem in multi-vehicle collision scenarios. This collision avoidance model of multi-agents model is feasible and effective, and can provide richer and closer-to-life virtual scene for driving simulator, reflecting real-life traffic environment more truly, this model can also promote the practicality of driving simulator.
基金Under the auspices of the National Natural Science Foundation of China(No.41590844)the Independent Research Program of Tsinghai University(No.2015THZ01)
文摘The pace and scale of China＇s contemporary urbanization are stunning. This paper reviews process and the underlying driving forces of China＇s urbanization between 1949-2015. Contemporary China＇s urbanization has experienced four stages, and each has had different driving forces： 1） economic re-construction and industrialization-led urbanization 0949-1977）; 2） economic reform and mar- ket-led urbanization （1978-1995）; 3） economic globalization and the global-local urbanization （1996-2010）; and 4） the land-economy- led urbanization （2010-）. These urbanization processes and driving forces will undoubtedly provide scientific reference and have sig- nificant implications for developing countries, especially African countries, to formulate their urbanization public policies.
文摘Based on the long-term serial NOAA/NDVI dataset during 1983-1999 and SPOT/VGT dataset in 2001, the land use/cover change information in the 13 provinces of northern China was extracted based on the analysis of the cultivated landscape characteristics at first, then the effects of human activities on cultivated land process were explored by GIS and the driving forces of cultivated land change were investigated. The conclusions can be drawn as follows： （1） The constant increase of weak ecological function land as desert and cultivated land and the decrease of the ecological function land of forest and shrub were the main characteristics of the land use/cover change in the 13 provinces from 1983 to 1999, which showed the effects on the ecological adjustment fimction. However, such situations were changed to some extent in the 2000s because of the eco-construction policy of the government. （2） From 1983 to 2001, the Barycenter of cultivated land tended to move from northeast to southwest with the topography and transportation situations being the main influences on the cultivated land distribution. It is found that the cultivated land use intensity decreased noticably with the increase of distance from the main communication arteries. （3） The improvement of the people＇s living standard is closely related with the cultivated land change. The structural adjustment in the agricultural land caused by economic development and the improvement of the people＇s living standard ig an important factor affecting the cultivated land change in northern China from 1983 to 2001
基金Project(61673233)supported by the National Natural Science Foundation of ChinaProject(D171100006417003)supported by Beijing Municipal Science and Technology Program,China
文摘Cooperative driving around intersections has aroused increasing interest in the last five years.Meanwhile,driving safety in non-signalized intersections has become an issue that has attracted attention globally.In view of the potential collision risk when more than three vehicles approach a non-signalized intersection from different directions,we propose a driving model using cooperative game theory.First,the characteristic functions of this model are primarily established on each vehicle’s profit function and include safety,rapidity and comfort indicators.Second,the Shapley theorem is adopted,and its group rationality,individual rationality,and uniqueness are proved to be suitable for the characteristic functions of the model.Following this,different drivers’characteristics are considered.In order to simplify the calculation process,a zero-mean normalization method is introduced.In addition,a genetic algorithm method is adopted to search an optimal strategy set in the constrained multi-objective optimization problem.Finally,the model is confirmed as valid after simulation with a series of initial conditions.
基金This work was supported by the National Natural Science Foundation of China(51975310 and 52002209).
文摘In mixed and dynamic traffic environments,accurate long-term trajectory forecasting of surrounding vehicles is one of the indispensable preconditions for autonomous vehicles to accomplish reasonable behavioral decisions and guarantee driving safety.In this paper,we propose an integrated probabilistic architecture for long-term vehicle trajectory prediction,which consists of a driving inference model(DIM)and a trajectory prediction model(TPM).The DIM is designed and employed to accurately infer the potential driving intention based on a dynamic Bayesian network.The proposed DIM incorporates the basic traffic rules and multivariate vehicle motion information.To further improve the prediction accuracy and realize uncertainty estimation,we develop a Gaussian process-based TPM,considering both the short-term prediction results of the vehicle model and the driving motion characteristics.Afterward,the effectiveness of our novel approach is demonstrated by conducting experiments on a public naturalistic driving dataset under lane-changing scenarios.The superior performance on the task of long-term trajectory prediction is presented and verified by comparing with other advanced methods.
基金support from the National Natural Science Foundation of China(51575028)National Natural Science Foundation of China(51605258)the Fundamental Research Funds for the Central Universities of China(YWF-18-BJ-J-75)。
文摘The unsatisfied surface quality seriously impedes the wide application of incremental sheet forming(ISF)in industrial field.As a novel approach,the interpolator method is a promising strategy to enhance the surface quality in ISF.However,the mechanism for the improvement of surface quality and the influence of interpolator properties on surface roughness are not well understood.In this paper,the influences of process variables(i.e.tool diameter,step size and thickness of interpolators)on the forming process(e.g.surface roughness,forming force and geometric error)are investigated through a systematic experimental approach of central composite design(CCD)in two-point incremental sheet forming(TPIF).It is obtained that the increase in thickness of interpolators decreases the surface roughness in direction vertical to the tool path while increases the surface roughness in direction horizontal to the tool path.Nevertheless,the combined influence between thickness of interpolators and process parameters(tool diameter and step size)is limited.Meanwhile,the placement of interpolator has little influence on the effective forming force of blank.In addition,the geometric error enlarges with the increase of step size and thickness of interpolator while decreases firstly and then increase with an increase in tool diameter.Finally,the influencing mechanism of the interpolator method on surface quality can be attributed to the decrease of thecontact pressure due to the increase of contact area with the unchanged contact force.Meanwhile,the interpolator method eliminates the sliding friction on the surface of blank due to the stable relative position between the blank and the interpolator.
基金Under the auspices of the National Natural Science Foundation of China(No.49771073)Key Project of ChineseAcademy of Sciences(No.KZ952-J1-203)
文摘The studies of driving forces of regional land use change(LUC)are to reveal the real motivation behind the LUC and its interacting mechanism,so as to simulate and predict the process of LUC.Presently,studies rooting from different natural and socio-economic backgrounds and from different scales have deepened the people’s understanding and cognition to driving forces of regional LUC.Biophysical driving forces are relatively stable,and have the cumulating effects.Human driving forces are relatively active,and are main driving forces of short-term regional LUC.Existing regional LUC models can answer the three main problems:which contribution(why),which location(where)and what rate(when).But,regional land use system is defined as the self-organized system,usually affected by the cri-tical value area and sudden change,and controlled by different stages.To reduce the impact of critical threshold and break on land use system,the studies of LUC driving forces will aim at following priority areas:data linkage between remote sensing and no-remote sensing data;underlying driving force identification;driving factor quantification;driving factor scale dependence;and driving process integration simulation.
基金the Natural Science Foundation of Guangxi(No.2020GXNSFDA238011)the Open Fund Project of Guangxi Key Laboratory of Automation Detection Technology and Instrument(No.YQ21203)the Independent Research Project of Guangxi Key Laboratory of Auto Parts and Vehicle Technology(No.2020GKLACVTZZ02)。
文摘To prevent and reduce road traffic accidents and improve driver safety awareness and bad driving be-haviors,we propose a safety evaluation method for commercial vehicle driving behavior.Three driving style clas-sification indexes were extracted using driving data from commercial vehicles and four primary and ten secondary safety evaluation indicators.Based on the stability of commercial vehicles transporting goods,the acceleration index is divided into three levels according to the statistical third quartile,and the evaluation expression of the safety index evaluation is established.Drivers were divided into conservative,moderate,and radical using K-means++.The weights corresponding to each index were calculated using a combination of the analytic hierarchy process(AHP)and criteria importance through intercriteria correlation(CRITIC),and the driving behavior scores of various drivers were calculated according to the safety index score standard.The established AHP-CRITIC safety evaluation model was verified using the actual driving behavior data of commercial vehicle drivers.The calculation results show that the proposed evaluation model can clearly distinguish between the types of drivers with different driving styles,verifying its rationality and validity.The evaluation results can provide a reference for transportation management departments and enterprises.
