Connected vehicles enabled by communication technologies have the potential to improve trafc mobility and enhance roadway safety such that trafc information can be shared among vehicles and infrastructure.Fruitful spe...Connected vehicles enabled by communication technologies have the potential to improve trafc mobility and enhance roadway safety such that trafc information can be shared among vehicles and infrastructure.Fruitful speed advisory strategies have been proposed to smooth connected vehicle trajectories for better system performance with the help of diferent carfollowing models.Yet,there has been no such comparison about the impacts of various car-following models on the advisory strategies.Further,most of the existing studies consider a deterministic vehicle arriving pattern.The resulting model is easy to approach yet not realistic in representing realistic trafc patterns.This study proposes an Individual Variable Speed Limit(IVSL)trajectory planning problem at a signalized intersection and investigates the impacts of three popular car-following models on the IVSL.Both deterministic and stochastic IVSL models are formulated,and their performance is tested with numerical experiments.The results show that,compared to the benchmark(i.e.,without speed control),the proposed IVSL strategy with a deterministic arriving pattern achieves signifcant improvements in both mobility and fuel efciency across diferent trafc levels with all three car-following models.The improvement of the IVSL with the Gipps’model is the most remarkable.When the vehicle arriving patterns are stochastic,the IVSL improves travel time,fuel consumption,and system cost by 8.95%,19.11%,and 11.37%,respectively,compared to the benchmark without speed control.展开更多
This study aimed to develop a new junior doctor allocation plan,and evaluate its impact on the door-to-doctor time(DDT)of a specific patient population at the Accident&Emergency(A&E)department of Changi Genera...This study aimed to develop a new junior doctor allocation plan,and evaluate its impact on the door-to-doctor time(DDT)of a specific patient population at the Accident&Emergency(A&E)department of Changi General Hospital(CGH)in Singapore.The new junior doctor allocation plan was developed by solving an integer linear programming model with the objective of matching available junior doctors with the patient arrival pattern.Compared to the period prior to the new plan’s implementation at CGH A&E,the average daily median,95th percentile,and standard deviation of DDT of target population were observed to have been reduced by 9.7 minutes(27.3%),24.5 minutes(21.9%),and 8.5 minutes(23.2%),respectively,in the post-implementation period.These differences remained statistically significant after adjustment for differences in patient load and other relevant patient characteristics over the pre-and post-implementation periods.Majority,if not all,of the previous work on A&E staff allocation studies relied on simulation models to project the impact of new staff allocation plans on DDT performance.They did not report the extent of DDT improvement in the new plan actualized and experienced by A&E patients.This paper addresses this gap in A&E overcrowding management research.It offers empirical evidence,from an operational A&E,on DDT improvements achieved through implementation of a new junior doctor allocation plan that better matched patient arrival pattern compared to the past.展开更多
文摘Connected vehicles enabled by communication technologies have the potential to improve trafc mobility and enhance roadway safety such that trafc information can be shared among vehicles and infrastructure.Fruitful speed advisory strategies have been proposed to smooth connected vehicle trajectories for better system performance with the help of diferent carfollowing models.Yet,there has been no such comparison about the impacts of various car-following models on the advisory strategies.Further,most of the existing studies consider a deterministic vehicle arriving pattern.The resulting model is easy to approach yet not realistic in representing realistic trafc patterns.This study proposes an Individual Variable Speed Limit(IVSL)trajectory planning problem at a signalized intersection and investigates the impacts of three popular car-following models on the IVSL.Both deterministic and stochastic IVSL models are formulated,and their performance is tested with numerical experiments.The results show that,compared to the benchmark(i.e.,without speed control),the proposed IVSL strategy with a deterministic arriving pattern achieves signifcant improvements in both mobility and fuel efciency across diferent trafc levels with all three car-following models.The improvement of the IVSL with the Gipps’model is the most remarkable.When the vehicle arriving patterns are stochastic,the IVSL improves travel time,fuel consumption,and system cost by 8.95%,19.11%,and 11.37%,respectively,compared to the benchmark without speed control.
文摘This study aimed to develop a new junior doctor allocation plan,and evaluate its impact on the door-to-doctor time(DDT)of a specific patient population at the Accident&Emergency(A&E)department of Changi General Hospital(CGH)in Singapore.The new junior doctor allocation plan was developed by solving an integer linear programming model with the objective of matching available junior doctors with the patient arrival pattern.Compared to the period prior to the new plan’s implementation at CGH A&E,the average daily median,95th percentile,and standard deviation of DDT of target population were observed to have been reduced by 9.7 minutes(27.3%),24.5 minutes(21.9%),and 8.5 minutes(23.2%),respectively,in the post-implementation period.These differences remained statistically significant after adjustment for differences in patient load and other relevant patient characteristics over the pre-and post-implementation periods.Majority,if not all,of the previous work on A&E staff allocation studies relied on simulation models to project the impact of new staff allocation plans on DDT performance.They did not report the extent of DDT improvement in the new plan actualized and experienced by A&E patients.This paper addresses this gap in A&E overcrowding management research.It offers empirical evidence,from an operational A&E,on DDT improvements achieved through implementation of a new junior doctor allocation plan that better matched patient arrival pattern compared to the past.
