在LTE-A网络的过载场景中,机器类通信(Machine Type Communication,MTC)设备的突发性接入会使得网络发生严重的拥塞,甚至死锁,造成网络的接入效率低下.在可用前导资源有限的前提下,根据实时负载数控制发起接入的设备数可以有效降低前导...在LTE-A网络的过载场景中,机器类通信(Machine Type Communication,MTC)设备的突发性接入会使得网络发生严重的拥塞,甚至死锁,造成网络的接入效率低下.在可用前导资源有限的前提下,根据实时负载数控制发起接入的设备数可以有效降低前导的碰撞概率,但是控制方法尚不明确.为此,本文提出了一种接入类别限制(Access Class Barring,ACB)的动态接入机制来优化海量MTC的随机接入性能.建立了一种基于退避预测的估计模型,该模型根据重传的设备数和状态转移过程估计出了实时活跃的设备数.结合估计模型和ACB参数调整可以最优化实时成功接入的设备数,能够有效地提高设备的接入成功率.本文在不同负载强度场景下,将提出的ACB动态接入机制和现有的动态ACB机制的接入性能进行了比较.仿真结果证明,本文提出的ACB动态接入机制的接入成功率为100%.而且,与现有的ACB动态接入机制相比,所提的新方案的平均接入时延更低.展开更多
针对随机接入信道的拥塞问题,提出了一种基于Access Class Barring(ACB)的接入控制因子优化计算方法。通过分析混合网络中各终端成功接入基站的概率,获取达到最大成功接入率的控制因子。按照随机接入过程进行仿真,统计成功接入的终端数...针对随机接入信道的拥塞问题,提出了一种基于Access Class Barring(ACB)的接入控制因子优化计算方法。通过分析混合网络中各终端成功接入基站的概率,获取达到最大成功接入率的控制因子。按照随机接入过程进行仿真,统计成功接入的终端数量,与计算值进行比较。仿真结果表明:对于不同的系统拥塞程度,利用该优化计算方法能获取合适的接入控制因子,使两种类型终端的成功接入数量都达到最大值;根据各时隙中的拥塞终端数量动态地更新ACB因子即可达到解决拥塞问题的目的。展开更多
This paper will document and discuss the results of full scale flume testing of a tapered ACB(articulating concrete block)system utilizing a stabilized stone drainage layer(Shoretec EPEC)under both steady state and hy...This paper will document and discuss the results of full scale flume testing of a tapered ACB(articulating concrete block)system utilizing a stabilized stone drainage layer(Shoretec EPEC)under both steady state and hydraulic jump induced flow conditions.Articulated Concrete Block revetment systems have documented performance improvement when a stone drainage layer is included under the blocks,which was initially discovered in the late 1990’s and has largely remained an unstudied area of ACB testing for the past 25 years.In 2010,testing of a tapered ACB system was conducted in which the length of the test section was increased from 12.2 m to 21.3 m with a 10.2 cm thick stone drainage layer resulting in no apparent issues with the movement of the drainage layer.In 2013,more flume testing was conducted on a tapered ACB system in which the test section was increased from 21.3 m to 30.5 m and the stone drainage layer was increased from 10.2 cm to 15.2 cm.The results of this test showed significant ACB block movement at the 0.91,1.22 and 1.62 m OT(overtopping depth)depths,in some instances exceeding 6.35 cm.In 2017,a 27.4 m test flume was constructed for a tapered ACB system(Shoretec EPEC)utilizing 15.2 cm of stone as a drainage layer with a 3-dimensional load platform added for stone stabilization.The results of this test run showed that,at 1.62 m of OT depth,ACB block movement was kept to under 16 mm in the vertical and hydraulic jump stability was attained up to the maximum discharge flow of 2.579 m3/s/m on a 2:1 slope.Using the new design data,graphs will be presented showing the new range of hydraulic conditions now suitable for ACB tapered revetment systems with a stabilized stone drainage layer.In addition,design criteria necessary for the successful deployment of the 3-dimensional transfer platform system will be presented.展开更多
Weizhou 11-1N Platform is a large wellhead platform with much equipment. After ten years of development, the only low-voltage bus bars on the platform, namely LA, LB and LE bus bars, are already in overload operation,...Weizhou 11-1N Platform is a large wellhead platform with much equipment. After ten years of development, the only low-voltage bus bars on the platform, namely LA, LB and LE bus bars, are already in overload operation, and the chest of drawers of the low-voltage power distribution cabinet has no spare. In view of this problem, considering the follow-up development, according to the next five-year plan, the expansion transformation of low-voltage bus is proposed, i.e. a new low-voltage bus LC bus is added on the original basis, and LA and LC buses are expanded by transforming LA bus and adding ACB switch as bus coupler switch.展开更多
文摘在LTE-A网络的过载场景中,机器类通信(Machine Type Communication,MTC)设备的突发性接入会使得网络发生严重的拥塞,甚至死锁,造成网络的接入效率低下.在可用前导资源有限的前提下,根据实时负载数控制发起接入的设备数可以有效降低前导的碰撞概率,但是控制方法尚不明确.为此,本文提出了一种接入类别限制(Access Class Barring,ACB)的动态接入机制来优化海量MTC的随机接入性能.建立了一种基于退避预测的估计模型,该模型根据重传的设备数和状态转移过程估计出了实时活跃的设备数.结合估计模型和ACB参数调整可以最优化实时成功接入的设备数,能够有效地提高设备的接入成功率.本文在不同负载强度场景下,将提出的ACB动态接入机制和现有的动态ACB机制的接入性能进行了比较.仿真结果证明,本文提出的ACB动态接入机制的接入成功率为100%.而且,与现有的ACB动态接入机制相比,所提的新方案的平均接入时延更低.
文摘针对随机接入信道的拥塞问题,提出了一种基于Access Class Barring(ACB)的接入控制因子优化计算方法。通过分析混合网络中各终端成功接入基站的概率,获取达到最大成功接入率的控制因子。按照随机接入过程进行仿真,统计成功接入的终端数量,与计算值进行比较。仿真结果表明:对于不同的系统拥塞程度,利用该优化计算方法能获取合适的接入控制因子,使两种类型终端的成功接入数量都达到最大值;根据各时隙中的拥塞终端数量动态地更新ACB因子即可达到解决拥塞问题的目的。
文摘This paper will document and discuss the results of full scale flume testing of a tapered ACB(articulating concrete block)system utilizing a stabilized stone drainage layer(Shoretec EPEC)under both steady state and hydraulic jump induced flow conditions.Articulated Concrete Block revetment systems have documented performance improvement when a stone drainage layer is included under the blocks,which was initially discovered in the late 1990’s and has largely remained an unstudied area of ACB testing for the past 25 years.In 2010,testing of a tapered ACB system was conducted in which the length of the test section was increased from 12.2 m to 21.3 m with a 10.2 cm thick stone drainage layer resulting in no apparent issues with the movement of the drainage layer.In 2013,more flume testing was conducted on a tapered ACB system in which the test section was increased from 21.3 m to 30.5 m and the stone drainage layer was increased from 10.2 cm to 15.2 cm.The results of this test showed significant ACB block movement at the 0.91,1.22 and 1.62 m OT(overtopping depth)depths,in some instances exceeding 6.35 cm.In 2017,a 27.4 m test flume was constructed for a tapered ACB system(Shoretec EPEC)utilizing 15.2 cm of stone as a drainage layer with a 3-dimensional load platform added for stone stabilization.The results of this test run showed that,at 1.62 m of OT depth,ACB block movement was kept to under 16 mm in the vertical and hydraulic jump stability was attained up to the maximum discharge flow of 2.579 m3/s/m on a 2:1 slope.Using the new design data,graphs will be presented showing the new range of hydraulic conditions now suitable for ACB tapered revetment systems with a stabilized stone drainage layer.In addition,design criteria necessary for the successful deployment of the 3-dimensional transfer platform system will be presented.
文摘Weizhou 11-1N Platform is a large wellhead platform with much equipment. After ten years of development, the only low-voltage bus bars on the platform, namely LA, LB and LE bus bars, are already in overload operation, and the chest of drawers of the low-voltage power distribution cabinet has no spare. In view of this problem, considering the follow-up development, according to the next five-year plan, the expansion transformation of low-voltage bus is proposed, i.e. a new low-voltage bus LC bus is added on the original basis, and LA and LC buses are expanded by transforming LA bus and adding ACB switch as bus coupler switch.
