Ethernet link aggregation, which provides an easy and cost-effective way to increase both bandwidth and link availability between a pair of devices, is well suited for data center networks. However, all the traffic sp...Ethernet link aggregation, which provides an easy and cost-effective way to increase both bandwidth and link availability between a pair of devices, is well suited for data center networks. However, all the traffic splitting algorithms used in existing Ethernet link aggregation are flow-level which do not work well owing to the traffic characteristics of data centers. Though frame-level traffic splitting can achieve optimal load balance and the maximum benefits from aggregated capacity, it is generally deprecated in most cases because of frame disordering which can disrupt the operation of many Internet protocols, most notably transmission control protocol （TCP）. To address this issue, we first investigate the causes of frame disordering in link aggregation and find that all of them either are no longer true or can be prevented in data centers. Then we present a byte-counter frame-level traffic splitting algorithm which achieves optimal performance while causes no frame disordering. The only requirement is that frames in a flow are the same size which can be easily met in data centers. Simulation results show that the proposed frame-level traffic splitting method could achieve higher throughput and optimal load balance. The average completion time of different sized flows is reduced by 24% on average and by up to 46%.展开更多
This paper deals with the irregular profile of braced steel frame building in vertical direction with shear link bracing systems.The underlying fact of the paper is the effect of seismic force in braced frames with di...This paper deals with the irregular profile of braced steel frame building in vertical direction with shear link bracing systems.The underlying fact of the paper is the effect of seismic force in braced frames with different types of irregularities including mass irregularity,mass discontinuity and overhanging mass.For each successive model,the position of shear link bracings has been fixed to make the study effective.This study has investigated the vulnerable effect of irregular profiles in steel frame buildings.To attain the behavior of each frame,linear time history analysis method has been adopted for the present study.FEMA356 standard has been used here for linear time history analysis.Investigations on different frames exhibit that regular profile with symmetry in mass is more efficient while using overhanging mass is detrimental considering the time dependent displacements and accelerations.展开更多
This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears...This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears, and set up approximate formulas for modification coefficients of gears for the first time. And the principles of transmitting rate designing for the system are given. The calculating results demonstrate that the new design method satisfies the demands of processing technology. This mechanism has been used successfully in the kind of rubbed roving frame.展开更多
基金supported by the National Natural Science Foundation of China(61002011)the Open Fund of the State Key Laboratory of Software Development Environment(SKLSDE-2009KF-2-08)+1 种基金the National Basic Research Program of China(2009CB320505)the Hi-Tech Research and Development Program of China(2011AA01A102)
文摘Ethernet link aggregation, which provides an easy and cost-effective way to increase both bandwidth and link availability between a pair of devices, is well suited for data center networks. However, all the traffic splitting algorithms used in existing Ethernet link aggregation are flow-level which do not work well owing to the traffic characteristics of data centers. Though frame-level traffic splitting can achieve optimal load balance and the maximum benefits from aggregated capacity, it is generally deprecated in most cases because of frame disordering which can disrupt the operation of many Internet protocols, most notably transmission control protocol （TCP）. To address this issue, we first investigate the causes of frame disordering in link aggregation and find that all of them either are no longer true or can be prevented in data centers. Then we present a byte-counter frame-level traffic splitting algorithm which achieves optimal performance while causes no frame disordering. The only requirement is that frames in a flow are the same size which can be easily met in data centers. Simulation results show that the proposed frame-level traffic splitting method could achieve higher throughput and optimal load balance. The average completion time of different sized flows is reduced by 24% on average and by up to 46%.
文摘This paper deals with the irregular profile of braced steel frame building in vertical direction with shear link bracing systems.The underlying fact of the paper is the effect of seismic force in braced frames with different types of irregularities including mass irregularity,mass discontinuity and overhanging mass.For each successive model,the position of shear link bracings has been fixed to make the study effective.This study has investigated the vulnerable effect of irregular profiles in steel frame buildings.To attain the behavior of each frame,linear time history analysis method has been adopted for the present study.FEMA356 standard has been used here for linear time history analysis.Investigations on different frames exhibit that regular profile with symmetry in mass is more efficient while using overhanging mass is detrimental considering the time dependent displacements and accelerations.
文摘This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears, and set up approximate formulas for modification coefficients of gears for the first time. And the principles of transmitting rate designing for the system are given. The calculating results demonstrate that the new design method satisfies the demands of processing technology. This mechanism has been used successfully in the kind of rubbed roving frame.
