IEEE 802.11p has been proposed to extend the application of IEEE 802.11 to Wireless Access fast fading Vehicular Environments (WAVE).Due to the high velocities of vehicles and thus the inconstant topology of networks,...IEEE 802.11p has been proposed to extend the application of IEEE 802.11 to Wireless Access fast fading Vehicular Environments (WAVE).Due to the high velocities of vehicles and thus the inconstant topology of networks,it is extremely difficult to maintain communications without handoff in an Internet of Vehicles (IoV).Hence,fast handoff from one roadside unit (RSU) to another is necessary.Although some solutions have been given in IEEE 802.11r and 802.11f standards,the handoff latency is still as high as about 50 ms when adopting them.To address this issue in WAVE systems,a novel position-based handoff (PHO) scheme is proposed in this paper.In PHO scheme,the triggering of the handoff is accomplished by the location information of a vehicle instead of the power level of the received signal.Both the handoff process and latency of PHO scheme are analyzed.Finally,to verify the analytical results,simulations were conducted to date the effectiveness of the proposed PHO scheme.展开更多
The 84-km long Changbai Mountain scenic Ring highway encircles and bisects the nature reserve. With the expected increasing traffic flow, increased wildlife vehicle collisions and barrier effects are likely. In order ...The 84-km long Changbai Mountain scenic Ring highway encircles and bisects the nature reserve. With the expected increasing traffic flow, increased wildlife vehicle collisions and barrier effects are likely. In order to identify wildlife crossing zones and future protective measurement, the authors carried out 10 wildlife highway crossing surveys during the winter in 2008-2009. For each 5-kin section, the authors recorded highway crossings of all small/mid-sized and large mammals and one large protected bird species, the hazel grouse （Bonasa bonasia） and noted snow depth and the dominant vegetation type. The authors detected 12 mammal species and one avifauna species crossing the highway 502 times. The smallest of mammal was the Eurasian red squirrel （Sciurus vulgaris）. Large mammals detected included the wild boar （Sus scrofe） （64） and brown bear （Ursus arctos） （1）. The average number of wildlife crossings per 5 km was 29.5. It was found that species richness and crossing frequency was higher in sections with broad leaf forest compared to sections with white birch secondary forest significantly. The authors suggested that disturbance of broad leaf forest be minimized during construction and strict protection be established for broad leaf forests around Changbai Mountain National Nature Reserve.展开更多
指出在高速铁路牵引供电系统故障诊断中应计及所获取的保护和开关动作信息的不确信性和模糊性,基于此,将模糊Petri网(fuzzy Petri net,FPN)应用于牵引供电系统的故障诊断。考虑到牵引供电系统保护的特殊性,进行了第2次推理;针对越区供...指出在高速铁路牵引供电系统故障诊断中应计及所获取的保护和开关动作信息的不确信性和模糊性,基于此,将模糊Petri网(fuzzy Petri net,FPN)应用于牵引供电系统的故障诊断。考虑到牵引供电系统保护的特殊性,进行了第2次推理;针对越区供电时馈线远后备保护覆盖元件多的特点,增加了推理条件以保证推理的正确性;根据供电臂故障特征,给出了供电臂故障区间判别规则。算例分析结果表明,牵引供电系统的模糊Petri网故障诊断方法简洁、推理直观,能够在不确定或信息缺失的情况下,提高故障区域判断的确信性。展开更多
基金supported in part by National Natural Science Foundation of China(Grant Nos.60971082,60872049,60972073,and60871042)National Key Basic Research Program of China(Grant No.2009CB320407)+1 种基金National Great Science Specific Project(Grant No.2009ZX03003-001,2009ZX03003-011,2010ZX03001003)Chinese Universities Scientific Fund,China
文摘IEEE 802.11p has been proposed to extend the application of IEEE 802.11 to Wireless Access fast fading Vehicular Environments (WAVE).Due to the high velocities of vehicles and thus the inconstant topology of networks,it is extremely difficult to maintain communications without handoff in an Internet of Vehicles (IoV).Hence,fast handoff from one roadside unit (RSU) to another is necessary.Although some solutions have been given in IEEE 802.11r and 802.11f standards,the handoff latency is still as high as about 50 ms when adopting them.To address this issue in WAVE systems,a novel position-based handoff (PHO) scheme is proposed in this paper.In PHO scheme,the triggering of the handoff is accomplished by the location information of a vehicle instead of the power level of the received signal.Both the handoff process and latency of PHO scheme are analyzed.Finally,to verify the analytical results,simulations were conducted to date the effectiveness of the proposed PHO scheme.
文摘The 84-km long Changbai Mountain scenic Ring highway encircles and bisects the nature reserve. With the expected increasing traffic flow, increased wildlife vehicle collisions and barrier effects are likely. In order to identify wildlife crossing zones and future protective measurement, the authors carried out 10 wildlife highway crossing surveys during the winter in 2008-2009. For each 5-kin section, the authors recorded highway crossings of all small/mid-sized and large mammals and one large protected bird species, the hazel grouse （Bonasa bonasia） and noted snow depth and the dominant vegetation type. The authors detected 12 mammal species and one avifauna species crossing the highway 502 times. The smallest of mammal was the Eurasian red squirrel （Sciurus vulgaris）. Large mammals detected included the wild boar （Sus scrofe） （64） and brown bear （Ursus arctos） （1）. The average number of wildlife crossings per 5 km was 29.5. It was found that species richness and crossing frequency was higher in sections with broad leaf forest compared to sections with white birch secondary forest significantly. The authors suggested that disturbance of broad leaf forest be minimized during construction and strict protection be established for broad leaf forests around Changbai Mountain National Nature Reserve.
文摘指出在高速铁路牵引供电系统故障诊断中应计及所获取的保护和开关动作信息的不确信性和模糊性,基于此,将模糊Petri网(fuzzy Petri net,FPN)应用于牵引供电系统的故障诊断。考虑到牵引供电系统保护的特殊性,进行了第2次推理;针对越区供电时馈线远后备保护覆盖元件多的特点,增加了推理条件以保证推理的正确性;根据供电臂故障特征,给出了供电臂故障区间判别规则。算例分析结果表明,牵引供电系统的模糊Petri网故障诊断方法简洁、推理直观,能够在不确定或信息缺失的情况下,提高故障区域判断的确信性。
