Current traffic signal split failure (SF) estimations derived from high-resolution controller event data rely on detector occupancy ratios and preset thresholds. The reliability of these techniques depends on the sele...Current traffic signal split failure (SF) estimations derived from high-resolution controller event data rely on detector occupancy ratios and preset thresholds. The reliability of these techniques depends on the selected thresholds, detector lengths, and vehicle arrival patterns. Connected vehicle (CV) trajectory data can more definitively show when a vehicle split fails by evaluating the number of stops it experiences as it approaches an intersection, but it has limited market penetration. This paper compares cycle-by-cycle SF estimations from both high-resolution controller event data and CV trajectory data, and evaluates the effect of data aggregation on SF agreement between the two techniques. Results indicate that, in general, split failure events identified from CV data are likely to also be captured from high-resolution data, but split failure events identified from high-resolution data are less likely to be captured from CV data. This is due to the CV market penetration rate (MPR) of ~5% being too low to capture representative data for every controller cycle. However, data aggregation can increase the ratio in which CV data captures split failure events. For example, day-of-week data aggregation increased the percentage of split failures identified with high-resolution data that were also captured with CV data from 35% to 56%. It is recommended that aggregated CV data be used to estimate SF as it provides conservative and actionable results without the limitations of intersection and detector configuration. As the CV MPR increases, the accuracy of CV-based SF estimation will also improve.展开更多
从“人-机-环境”的角度对导致火灾探测器误报、漏报的原因进行了分析,利用 Monte carlo 系统仿真方法对火灾探测器的可靠性进行了模拟分析,得到的探测器可靠度、故障率曲线与理论和工程实际情况相符。正确地描述了火灾探测器的故障率...从“人-机-环境”的角度对导致火灾探测器误报、漏报的原因进行了分析,利用 Monte carlo 系统仿真方法对火灾探测器的可靠性进行了模拟分析,得到的探测器可靠度、故障率曲线与理论和工程实际情况相符。正确地描述了火灾探测器的故障率随时间变化的规律,为进一步应用该方法来分析整个火灾探测报警系统的可靠性提供了理论基础。展开更多
This paper considers the eventual leader election problem in asynchronous message-passing systems where an arbitrary number t of processes can crash（t〈n,where n is the total number of processes）.It considers weak a...This paper considers the eventual leader election problem in asynchronous message-passing systems where an arbitrary number t of processes can crash（t〈n,where n is the total number of processes）.It considers weak assumptions both on the initial knowledge of the processes and on the network behavior.More precisely,initially,a process knows only its identity and the fact that the process identities are different and totally ordered（it knows neither n nor t）.Two eventual leader election protocols and a lower bound are presented.The first protocol assumes that a process also knows a lower bound α on the number of processes that do not crash.This protocol requires the following behavioral properties from the underlying network：the graph made up of the correct processes and fair lossy links is strongly connected,and there is a correct process connected to（n〈f）-α other correct processes（where f is the actual number of crashes in the considered run） through eventually timely paths（paths made up of correct processes and eventually timely links）.This protocol is not communication-efficient in the sense that each correct process has to send messages forever.The second protocol is communication-efficient：after some time,only the final common leader has to send messages forever.This protocol does not require the processes to know α,but requires stronger properties from the underlying network：each pair of correct processes has to be connected by fair lossy links（one in each direction）,and there is a correct process whose n〈f-1 output links to the rest of correct processes have to be eventually timely.A matching lower bound result shows that any eventual leader election protocol must have runs with this number of eventually timely links,even if all processes know all the processes identities.In addition to being communication-efficient,the second protocol has another noteworthy efficiency property,namely,be the run finite or infinite,all the local variables and message fields have a finite展开更多
文摘Current traffic signal split failure (SF) estimations derived from high-resolution controller event data rely on detector occupancy ratios and preset thresholds. The reliability of these techniques depends on the selected thresholds, detector lengths, and vehicle arrival patterns. Connected vehicle (CV) trajectory data can more definitively show when a vehicle split fails by evaluating the number of stops it experiences as it approaches an intersection, but it has limited market penetration. This paper compares cycle-by-cycle SF estimations from both high-resolution controller event data and CV trajectory data, and evaluates the effect of data aggregation on SF agreement between the two techniques. Results indicate that, in general, split failure events identified from CV data are likely to also be captured from high-resolution data, but split failure events identified from high-resolution data are less likely to be captured from CV data. This is due to the CV market penetration rate (MPR) of ~5% being too low to capture representative data for every controller cycle. However, data aggregation can increase the ratio in which CV data captures split failure events. For example, day-of-week data aggregation increased the percentage of split failures identified with high-resolution data that were also captured with CV data from 35% to 56%. It is recommended that aggregated CV data be used to estimate SF as it provides conservative and actionable results without the limitations of intersection and detector configuration. As the CV MPR increases, the accuracy of CV-based SF estimation will also improve.
文摘从“人-机-环境”的角度对导致火灾探测器误报、漏报的原因进行了分析,利用 Monte carlo 系统仿真方法对火灾探测器的可靠性进行了模拟分析,得到的探测器可靠度、故障率曲线与理论和工程实际情况相符。正确地描述了火灾探测器的故障率随时间变化的规律,为进一步应用该方法来分析整个火灾探测报警系统的可靠性提供了理论基础。
基金supported by the Comunidad de Madrid under Grant No.S2009/TIC-1692the Spanish MEC under Grant Nos.TIN2007-67353-C02-01 and TIN2008-06735-C02-01
文摘This paper considers the eventual leader election problem in asynchronous message-passing systems where an arbitrary number t of processes can crash（t〈n,where n is the total number of processes）.It considers weak assumptions both on the initial knowledge of the processes and on the network behavior.More precisely,initially,a process knows only its identity and the fact that the process identities are different and totally ordered（it knows neither n nor t）.Two eventual leader election protocols and a lower bound are presented.The first protocol assumes that a process also knows a lower bound α on the number of processes that do not crash.This protocol requires the following behavioral properties from the underlying network：the graph made up of the correct processes and fair lossy links is strongly connected,and there is a correct process connected to（n〈f）-α other correct processes（where f is the actual number of crashes in the considered run） through eventually timely paths（paths made up of correct processes and eventually timely links）.This protocol is not communication-efficient in the sense that each correct process has to send messages forever.The second protocol is communication-efficient：after some time,only the final common leader has to send messages forever.This protocol does not require the processes to know α,but requires stronger properties from the underlying network：each pair of correct processes has to be connected by fair lossy links（one in each direction）,and there is a correct process whose n〈f-1 output links to the rest of correct processes have to be eventually timely.A matching lower bound result shows that any eventual leader election protocol must have runs with this number of eventually timely links,even if all processes know all the processes identities.In addition to being communication-efficient,the second protocol has another noteworthy efficiency property,namely,be the run finite or infinite,all the local variables and message fields have a finite
