Curved segments account for a disproportionately high proportion of fatal and serious injury crashes,with most of these crashes occurring on rural two-lane(R2L)highways.During the 10-year period from 2008 to 2017,a to...Curved segments account for a disproportionately high proportion of fatal and serious injury crashes,with most of these crashes occurring on rural two-lane(R2L)highways.During the 10-year period from 2008 to 2017,a total of 1234 fatal single-vehicle roadway departure(SV-RwD)crashes occurred on R2L roads in Louisiana,out of which 635(51.5%)crashes occurred on curved segments.Therefore,it is critical to investigate the causes of SV-RwD crashes,specifically those that occur on curved segments.This study aimed to investigate the‘association knowledge’of the factors contributing to SV-RwD crashes on R2L curved segments in Louisiana using fatal and injury crash data collected from 2008 to 2017.The study utilized Cluster Correspondence Analysis(CCA),a robust joint dimen-sion reduction and clustering method for handling high-dimensionality and multicollinear-ity of crash data,to achieve this objective.Based on the cluster validation measures,the study identified five clusters with specific traits,including alcohol-impaired male drivers with no seatbelt usage,young(15–24 years old)female drivers’crash involvement in cloudy weather conditions,animal-involved crashes in rainy weather conditions,crashes occurring on hillcrest locations under cloudy weather conditions,and crashes in the dark with the presence of streetlights and higher traffic volume.Furthermore,young(15–24 years)female drivers were identified in most clusters,implying that this specific age group of female drivers requires special consideration when dealing with SV-RwD colli-sions on R2L curved segments.To improve safety on R2L curved segments,policymakers can use the findings of this study to develop targeted countermeasures.展开更多
By adopting the method of controlling parameters this paper describes the construction of various kinds of cubic curve segment and curved surface fragment with rational and non rational parameters, and discusses the ...By adopting the method of controlling parameters this paper describes the construction of various kinds of cubic curve segment and curved surface fragment with rational and non rational parameters, and discusses the relationship between controlling parameters, weighted factors and types, kinds and characteristics of curve segments and curved surface fragments. A mathematical method is provided for CAGD with abundant connotations, broad covering region, convenience, flexibility and direct simplicity.展开更多
We propose a two-stage method for detecting circular objects in this paper. In the first stage, curves are divided as linear segments or nonlinear segments. A least square estimator is used to find the estimated cente...We propose a two-stage method for detecting circular objects in this paper. In the first stage, curves are divided as linear segments or nonlinear segments. A least square estimator is used to find the estimated centers and radii of the nonlinear segments in the second stage. The found centers and radii are then evaluated to see if there exist circles in the nonlinear segments. Both of the broken and occluded circular objects are evaluated for the proposed method. From the experimental results, it is seen that the proposed method is efficient.展开更多
Path planning for field agricultural robots must satisfy several criteria:establishing feeding routes,maintaining gentle slopes,approaching multiple livestock observation points,ensuring timely environmental monitorin...Path planning for field agricultural robots must satisfy several criteria:establishing feeding routes,maintaining gentle slopes,approaching multiple livestock observation points,ensuring timely environmental monitoring,and achieving high efficiency.The complex terrain of outdoor farming areas poses a challenge.Traditional A*algorithms,which generate only the shortest path,fail to meet these requirements and often produce paths that lack smoothness.Therefore,identifying the most suitable path,rather than merely the shortest one,is essential.This study introduced a path-planning algorithm tailored to field-based livestock farming environments,building upon the traditional A*algorithm.It constructed a digital elevation model,integrated an artificial potential field for evaluating multiple target points,calculated terrain slope,optimized the search neighborhood based on robot traversability,and employed Bézier curve segmentation for path optimization.This method segmented the path into multiple curves by evaluating the slopes of the lines connecting adjacent nodes,ensuring a smoother and more efficient route.The experimental results demonstrate its superiority to traditional A^(*),ensuring paths near multiple target points,significantly reducing the search space,and resulting in over 69.4%faster search speeds.Bézier curve segmentation delivers smoother paths conforming to robot trajectories.展开更多
文摘Curved segments account for a disproportionately high proportion of fatal and serious injury crashes,with most of these crashes occurring on rural two-lane(R2L)highways.During the 10-year period from 2008 to 2017,a total of 1234 fatal single-vehicle roadway departure(SV-RwD)crashes occurred on R2L roads in Louisiana,out of which 635(51.5%)crashes occurred on curved segments.Therefore,it is critical to investigate the causes of SV-RwD crashes,specifically those that occur on curved segments.This study aimed to investigate the‘association knowledge’of the factors contributing to SV-RwD crashes on R2L curved segments in Louisiana using fatal and injury crash data collected from 2008 to 2017.The study utilized Cluster Correspondence Analysis(CCA),a robust joint dimen-sion reduction and clustering method for handling high-dimensionality and multicollinear-ity of crash data,to achieve this objective.Based on the cluster validation measures,the study identified five clusters with specific traits,including alcohol-impaired male drivers with no seatbelt usage,young(15–24 years old)female drivers’crash involvement in cloudy weather conditions,animal-involved crashes in rainy weather conditions,crashes occurring on hillcrest locations under cloudy weather conditions,and crashes in the dark with the presence of streetlights and higher traffic volume.Furthermore,young(15–24 years)female drivers were identified in most clusters,implying that this specific age group of female drivers requires special consideration when dealing with SV-RwD colli-sions on R2L curved segments.To improve safety on R2L curved segments,policymakers can use the findings of this study to develop targeted countermeasures.
文摘By adopting the method of controlling parameters this paper describes the construction of various kinds of cubic curve segment and curved surface fragment with rational and non rational parameters, and discusses the relationship between controlling parameters, weighted factors and types, kinds and characteristics of curve segments and curved surface fragments. A mathematical method is provided for CAGD with abundant connotations, broad covering region, convenience, flexibility and direct simplicity.
基金supported by the I-Shou University under Grant No.ISU 102-05-01
文摘We propose a two-stage method for detecting circular objects in this paper. In the first stage, curves are divided as linear segments or nonlinear segments. A least square estimator is used to find the estimated centers and radii of the nonlinear segments in the second stage. The found centers and radii are then evaluated to see if there exist circles in the nonlinear segments. Both of the broken and occluded circular objects are evaluated for the proposed method. From the experimental results, it is seen that the proposed method is efficient.
基金supported by the Subject construction projects in specific universities(Grant No.2023B10564003)the Science and Technology Rural Commissioner Project of Guangzhou(Grant No.20212100026).
文摘Path planning for field agricultural robots must satisfy several criteria:establishing feeding routes,maintaining gentle slopes,approaching multiple livestock observation points,ensuring timely environmental monitoring,and achieving high efficiency.The complex terrain of outdoor farming areas poses a challenge.Traditional A*algorithms,which generate only the shortest path,fail to meet these requirements and often produce paths that lack smoothness.Therefore,identifying the most suitable path,rather than merely the shortest one,is essential.This study introduced a path-planning algorithm tailored to field-based livestock farming environments,building upon the traditional A*algorithm.It constructed a digital elevation model,integrated an artificial potential field for evaluating multiple target points,calculated terrain slope,optimized the search neighborhood based on robot traversability,and employed Bézier curve segmentation for path optimization.This method segmented the path into multiple curves by evaluating the slopes of the lines connecting adjacent nodes,ensuring a smoother and more efficient route.The experimental results demonstrate its superiority to traditional A^(*),ensuring paths near multiple target points,significantly reducing the search space,and resulting in over 69.4%faster search speeds.Bézier curve segmentation delivers smoother paths conforming to robot trajectories.
