The quality of real time traffic information is of the great importance, therefore the factors having effect on traffic characteristics are analyzed in general, and the necessities of real time data processing are sum...The quality of real time traffic information is of the great importance, therefore the factors having effect on traffic characteristics are analyzed in general, and the necessities of real time data processing are summarized. The identification and reconstruction of real time traffic data are analyzed using Kalman filter equation and statistical approach. Four methods for ITS (Intelligent transportation system) detector data screening in traffic management systems are discussed in detail. Meanwhile traffic data examinations are discussed with solutions formulated through analysis, and recommendations are made for information collection and data management in future.展开更多
The accurate estimation of road traffic states can provide decision making for travelers and traffic managers. In this work,an algorithm based on kernel-k nearest neighbor(KNN) matching of road traffic spatial charact...The accurate estimation of road traffic states can provide decision making for travelers and traffic managers. In this work,an algorithm based on kernel-k nearest neighbor(KNN) matching of road traffic spatial characteristics is presented to estimate road traffic states. Firstly, the representative road traffic state data were extracted to establish the reference sequences of road traffic running characteristics(RSRTRC). Secondly, the spatial road traffic state data sequence was selected and the kernel function was constructed, with which the spatial road traffic data sequence could be mapped into a high dimensional feature space. Thirdly, the referenced and current spatial road traffic data sequences were extracted and the Euclidean distances in the feature space between them were obtained. Finally, the road traffic states were estimated from weighted averages of the selected k road traffic states, which corresponded to the nearest Euclidean distances. Several typical links in Beijing were adopted for case studies. The final results of the experiments show that the accuracy of this algorithm for estimating speed and volume is 95.27% and 91.32% respectively, which prove that this road traffic states estimation approach based on kernel-KNN matching of road traffic spatial characteristics is feasible and can achieve a high accuracy.展开更多
This paper studies a routing protocol used in the application of collecting real-time traffic information using mobile vehicles to monitor traffic status. The biggest challenge of vehicular ad hoe network routing prot...This paper studies a routing protocol used in the application of collecting real-time traffic information using mobile vehicles to monitor traffic status. The biggest challenge of vehicular ad hoe network routing protocol lies in the mismatch between the direction of moving vehicles and routed data. In order to deal with this mismatch, a mesh based routing protocol with a two-tier network architecture is proposed. By using mesh nodes deployed at intersections, data can be routed through an optimized path which can improve the delivery ratio and reduce the consumption of network resources. The simulation uses the mobility model processed from the GPS data of taxis mnning in Shanghai urban areas. The result shows that the proposed protocol outperforms the existing flooding protocol.展开更多
Objective： To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran. Methods： Data regarding spinal injuries including demogra...Objective： To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran. Methods： Data regarding spinal injuries including demographics, mechanism and level of spinal injury, abbreviated injury score, associated injuries and final fate of the patients were extracted from the Iranian national trauma registry database from 1999 to 2004. Results： A total of 619 patients with traumatic spine fractures were identified, of whom 68.5% were males. The peak frequency of these injuries occurred in the 21-40 year age-group. Accidental falls and road traffic crashes （RTCs） were the most common mechanisms of spinal fractures （47.2% and 44.1%, respectively）. RTCs tended to occur in younger patients compared with accidental falls. The most common spinal region for spinal fracture was the lumbar spine （53.63%）. Cervical spine fractures were significantly more common in RTCs, while lumbar spine fractures were more common in accidental falls （P〈0.001）. A total of 171 （27.6%）patients had associated non-spinal injuries, of whom 127 had associated extremity injuries, and 55 had head injuries. Thirty-six （5.6%） patients had spinal cord injury （SCI）.The injury severity score of the RTC group was significantly higher than that of accidental falls （P=-0.002）. Fifteen （4%） patients died of traumatic injuries. The rate of death was significantly higher in RTCs compared with accidental falls （5.1% vs 2.1%, P=0.039）. Conclusions： The patterns of spinal fractures are similar to those reported from developed countries. RTCs tend to affect the younger age population and are associated with a higher degree of associated injuries and mortality than accidental falls. Therefore preventive strategies should be based on reduction of the number and severity of RTCs.展开更多
文摘The quality of real time traffic information is of the great importance, therefore the factors having effect on traffic characteristics are analyzed in general, and the necessities of real time data processing are summarized. The identification and reconstruction of real time traffic data are analyzed using Kalman filter equation and statistical approach. Four methods for ITS (Intelligent transportation system) detector data screening in traffic management systems are discussed in detail. Meanwhile traffic data examinations are discussed with solutions formulated through analysis, and recommendations are made for information collection and data management in future.
基金Projects(LQ16E080012,LY14F030012)supported by the Zhejiang Provincial Natural Science Foundation,ChinaProject(61573317)supported by the National Natural Science Foundation of ChinaProject(2015001)supported by the Open Fund for a Key-Key Discipline of Zhejiang University of Technology,China
文摘The accurate estimation of road traffic states can provide decision making for travelers and traffic managers. In this work,an algorithm based on kernel-k nearest neighbor(KNN) matching of road traffic spatial characteristics is presented to estimate road traffic states. Firstly, the representative road traffic state data were extracted to establish the reference sequences of road traffic running characteristics(RSRTRC). Secondly, the spatial road traffic state data sequence was selected and the kernel function was constructed, with which the spatial road traffic data sequence could be mapped into a high dimensional feature space. Thirdly, the referenced and current spatial road traffic data sequences were extracted and the Euclidean distances in the feature space between them were obtained. Finally, the road traffic states were estimated from weighted averages of the selected k road traffic states, which corresponded to the nearest Euclidean distances. Several typical links in Beijing were adopted for case studies. The final results of the experiments show that the accuracy of this algorithm for estimating speed and volume is 95.27% and 91.32% respectively, which prove that this road traffic states estimation approach based on kernel-KNN matching of road traffic spatial characteristics is feasible and can achieve a high accuracy.
基金Supported by the National Basic Research Program of China (No. 2006CB303000)the National Natural Science Foundation of China (No. 60773091, F020303).
文摘This paper studies a routing protocol used in the application of collecting real-time traffic information using mobile vehicles to monitor traffic status. The biggest challenge of vehicular ad hoe network routing protocol lies in the mismatch between the direction of moving vehicles and routed data. In order to deal with this mismatch, a mesh based routing protocol with a two-tier network architecture is proposed. By using mesh nodes deployed at intersections, data can be routed through an optimized path which can improve the delivery ratio and reduce the consumption of network resources. The simulation uses the mobility model processed from the GPS data of taxis mnning in Shanghai urban areas. The result shows that the proposed protocol outperforms the existing flooding protocol.
文摘Objective： To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran. Methods： Data regarding spinal injuries including demographics, mechanism and level of spinal injury, abbreviated injury score, associated injuries and final fate of the patients were extracted from the Iranian national trauma registry database from 1999 to 2004. Results： A total of 619 patients with traumatic spine fractures were identified, of whom 68.5% were males. The peak frequency of these injuries occurred in the 21-40 year age-group. Accidental falls and road traffic crashes （RTCs） were the most common mechanisms of spinal fractures （47.2% and 44.1%, respectively）. RTCs tended to occur in younger patients compared with accidental falls. The most common spinal region for spinal fracture was the lumbar spine （53.63%）. Cervical spine fractures were significantly more common in RTCs, while lumbar spine fractures were more common in accidental falls （P〈0.001）. A total of 171 （27.6%）patients had associated non-spinal injuries, of whom 127 had associated extremity injuries, and 55 had head injuries. Thirty-six （5.6%） patients had spinal cord injury （SCI）.The injury severity score of the RTC group was significantly higher than that of accidental falls （P=-0.002）. Fifteen （4%） patients died of traumatic injuries. The rate of death was significantly higher in RTCs compared with accidental falls （5.1% vs 2.1%, P=0.039）. Conclusions： The patterns of spinal fractures are similar to those reported from developed countries. RTCs tend to affect the younger age population and are associated with a higher degree of associated injuries and mortality than accidental falls. Therefore preventive strategies should be based on reduction of the number and severity of RTCs.
