Unmanned aerial vehicle(UAV)was introduced as a novel traffic device to collect road traffic information and its cruise route planning problem was considered.Firstly,a multi-objective optimization model was proposed a...Unmanned aerial vehicle(UAV)was introduced as a novel traffic device to collect road traffic information and its cruise route planning problem was considered.Firstly,a multi-objective optimization model was proposed aiming at minimizing the total cruise distance and the number of UAVs used,which used UAV maximum cruise distance,the number of UAVs available and time window of each monitored target as constraints.Then,a novel multi-objective evolutionary algorithm was proposed.Next,a case study with three time window scenarios was implemented.The results show that both the total cruise distance and the number of UAVs used continue to increase with the time window constraint becoming narrower.Compared with the initial optimal solutions,the optimal total cruise distance and the number of UAVs used fall by an average of 30.93% and 31.74%,respectively.Finally,some concerns using UAV to collect road traffic information were discussed.展开更多
Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, ...Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.展开更多
The technical progress and the globalization accelerate rapidly the development of new disciplines and sub-disciplines. Consequently, new and specific terminology is necessary. In addition, the interdisciplinarity con...The technical progress and the globalization accelerate rapidly the development of new disciplines and sub-disciplines. Consequently, new and specific terminology is necessary. In addition, the interdisciplinarity contributes as well to the development of communication problems between non-professionals and experts of a special domain or between experts of different domains--as well at international level. Usually, technical terms are defined differently according to their domains. Therefore, a new terminological approach will avoid semantic vagueness as synonymy, antonymy, risk of confusion, hypernymy-hyponymy relations and polysemy, homonymy, etc.. For example, the terms ＂localization＂ and ＂positioning＂ are prototypes for this semantic vagueness. The objective of the iglos （＂intelligent glossary＂） terminology work of the Institute of Traffic Safety and Automation Engineering of the Technische Universigit Braunschweig is to clarify the multilingual and multidisciplinary misunderstanding between special languages of different domains by standardizing the definitions of technical terms. The focus of this paper lies on semantic problems of English navigation terminology in railway traffic domain and the clarification of the semantic vagueness between its terms with a modeling process and a linguistic method with different criteria. Finally, the result of these approaches should be a consistent navigation terminology in the railway domain.展开更多
A wide-angle beam propagation algorithm based on an oblique coordinate system is presented.A waveguide with tilted structure is simulated in terms of this method and the conventional wide-angle BPM. By comparing the r...A wide-angle beam propagation algorithm based on an oblique coordinate system is presented.A waveguide with tilted structure is simulated in terms of this method and the conventional wide-angle BPM. By comparing the results,it is found that this method is effective especially in tilted structure. The Y-junction has been also simulated in terms of this new method,and the good results are obtained.展开更多
基金Project(2009AA11Z220)supported by the National High Technology Research and Development Program of China
文摘Unmanned aerial vehicle(UAV)was introduced as a novel traffic device to collect road traffic information and its cruise route planning problem was considered.Firstly,a multi-objective optimization model was proposed aiming at minimizing the total cruise distance and the number of UAVs used,which used UAV maximum cruise distance,the number of UAVs available and time window of each monitored target as constraints.Then,a novel multi-objective evolutionary algorithm was proposed.Next,a case study with three time window scenarios was implemented.The results show that both the total cruise distance and the number of UAVs used continue to increase with the time window constraint becoming narrower.Compared with the initial optimal solutions,the optimal total cruise distance and the number of UAVs used fall by an average of 30.93% and 31.74%,respectively.Finally,some concerns using UAV to collect road traffic information were discussed.
文摘Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.
文摘The technical progress and the globalization accelerate rapidly the development of new disciplines and sub-disciplines. Consequently, new and specific terminology is necessary. In addition, the interdisciplinarity contributes as well to the development of communication problems between non-professionals and experts of a special domain or between experts of different domains--as well at international level. Usually, technical terms are defined differently according to their domains. Therefore, a new terminological approach will avoid semantic vagueness as synonymy, antonymy, risk of confusion, hypernymy-hyponymy relations and polysemy, homonymy, etc.. For example, the terms ＂localization＂ and ＂positioning＂ are prototypes for this semantic vagueness. The objective of the iglos （＂intelligent glossary＂） terminology work of the Institute of Traffic Safety and Automation Engineering of the Technische Universigit Braunschweig is to clarify the multilingual and multidisciplinary misunderstanding between special languages of different domains by standardizing the definitions of technical terms. The focus of this paper lies on semantic problems of English navigation terminology in railway traffic domain and the clarification of the semantic vagueness between its terms with a modeling process and a linguistic method with different criteria. Finally, the result of these approaches should be a consistent navigation terminology in the railway domain.
文摘A wide-angle beam propagation algorithm based on an oblique coordinate system is presented.A waveguide with tilted structure is simulated in terms of this method and the conventional wide-angle BPM. By comparing the results,it is found that this method is effective especially in tilted structure. The Y-junction has been also simulated in terms of this new method,and the good results are obtained.
