Development of control strategy of variable speed limits for improving traffic operations at freeway bottlenecks

A control strategy of variable speed limits(VSL)was developed to reduce the travel time at freeway recurrent bottleneck areas.The proposed control strategy particularly focused on preventing the capacity drop and increasing the discharge flow.A cell transmission model(CTM)was developed to evaluate the effects of the proposed VSL control strategy on the traffic operations.The results show that the total travel time is reduced by 25.5% and the delay is reduced by 56.1%.The average travel speed is increased by 34.3% and the queue length is reduced by 31.0%.The traffic operation is improved by the proposed VSL control strategy.The way to use the proposed VSL control strategy in different types of freeway bottlenecks was also discussed by considering different traffic flow characteristics.It is concluded that the VSL control strategy is effective for merge bottlenecks but is less effective for diverge bottlenecks.

论优先股的发行

股东平等原则的实质是股份平等,它要求相同股份相同权利,不同股份不同权利,优先股的存在与股东平等原则并不冲突。发行优先股影响股东权益至巨,因此,公司之发行授权有其必要。优先股的发行需关注其发行条款,透过合同性设计符合公司需要的优先股。在立法论上,优先股的发行条件、发行规模、发行时期、发行目的、发行条款均不宜由立法予以限制,以实践优先股的合同性格,从而满足公司融资之需要。