IEEE 802.16 systems adopt a "semi-dynamic" allocation mechanism of channel quality indicator (CQI) channels.However,low utilization ratio of CQI channels reduces the spectrum efficiency.So we propose an adap...IEEE 802.16 systems adopt a "semi-dynamic" allocation mechanism of channel quality indicator (CQI) channels.However,low utilization ratio of CQI channels reduces the spectrum efficiency.So we propose an adaptive management strategy of CQI channels based on an analysis model named "toy brick model" to improve the efficiency.The simulation results validate the improvement.展开更多
In this paper, we propose a flexible and fairness-oriented packet scheduling approach for 3GPP UTRAN long term evolution (LTE) type packet radio systems, building on the ordinary proportional fair (PF) scheduling prin...In this paper, we propose a flexible and fairness-oriented packet scheduling approach for 3GPP UTRAN long term evolution (LTE) type packet radio systems, building on the ordinary proportional fair (PF) scheduling principle and channel quality indicator (CQI) feedback. Special emphasis is also put on practical feedback reporting mechanisms, including the effects of mobile measurement and estimation errors, reporting delays, and CQI quantization and compression. The performance of the overall scheduling and feedback re-porting process is investigated in details, in terms of cell throughput, coverage and resource allocation fairness, by using extensive quasistatic cellular system simulations in practical OFDMA system environment with frequency reuse of 1. The performance simulations show that by using the proposed modified PF ap-proach, significant coverage improvements in the order of 50% can be obtained at the expense of only 10-15% throughput loss, for all reduced feedback reporting schemes. This reflects highly improved fairness in the radio resource management (RRM) compared to other existing schedulers, without essentially com-promising the cell capacity. Furthermore, we demonstrate the improved functionality increase in radio re-source management for UE’s utilizing multi-antenna diversity receivers.展开更多
With the rapid development of shipping industry,the volume of maritime logistics is also increasing.Tugboats are the first service station for ships,and the working efficiency tugboats directly affects the ship’s att...With the rapid development of shipping industry,the volume of maritime logistics is also increasing.Tugboats are the first service station for ships,and the working efficiency tugboats directly affects the ship’s attendance rate and the port’s service efficiency.Some domestic ports use one-way channel design due to the limitations of geographical position and natural factors.However,due to the particularity of the channel,the ships are entering and leaving the port in a disorderly manner and the tugboats are running empty,which causes problems in the port.Therefore,the port is in urgent need of improving the cooperative dispatching ability of one-way channel and tugboats.展开更多
According to the passage rules of ships in the bidirectional channel,the realistic conditions of the limited number of tugboats in the port are taken into account.This paper studies the problems faced in the integrate...According to the passage rules of ships in the bidirectional channel,the realistic conditions of the limited number of tugboats in the port are taken into account.This paper studies the problems faced in the integrated scheduling optimization in terms of ship arrival and departure and tugboat allocation in two-way channel.A mixed integer programming model with minimum waiting time was established,and a heuristic algorithm was designed to solve the problem.Experimental results show that the model and algorithm in this paper can effectively solve such problems and provide support for port management.展开更多
The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is propo...The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is proposed in this study,i.e.a half separated-half coupled cathode(HSHC)flow field which has two inlets but just one outlet.A 3D numerical PEMFC model is applied to study the effect of the HSHC flow field on PEMFC performance and its operating strategy in terms of operating conditions.The study results are shown as follows:Compared with the two conventional cathode flow fields,the HSHC flow field improves the water balance along the channel and increases the current density by 17.1%at a cathode stoichiometry of 3.25.It is because the HSHC flow field can overcome the water loss at channels upstream and the water accumulation at channels downstream.The draw water phenomenon(DWP)in the HSHC flow field is observed,which is mainly affected by the water vapor pressure of channel.Based on the DWP,cooling channel inlet flow rates can be used to adjust water balance,but severe water loss should be avoided.In addition,the inlet temperature control in HSHC flow field should be that cell temperature>cathode channel inlet temperature>cooling channel inlet temperature>ambient temperatures for better water balance.展开更多
自20世纪90年代以来,电子商务在全球迅猛发展并掀起一场新的商业革命。与此同时,业界不断在探索新的电子商务模式,近年来O2O(online to offline/offline to online)模式受到高度重视,并以爆棚式速度发展。O2O模式改变了原有电子商务环...自20世纪90年代以来,电子商务在全球迅猛发展并掀起一场新的商业革命。与此同时,业界不断在探索新的电子商务模式,近年来O2O(online to offline/offline to online)模式受到高度重视,并以爆棚式速度发展。O2O模式改变了原有电子商务环境下供应链的结构和特征,使供应链成员间的竞合博弈关系变得更为复杂,供应链管理的难度进一步加大。鉴于此,采用系统综述的方法,结合O2O模式的不同表现形式,从线上到线下、线下到线上、线上线下融合等3个方面对O2O供应链管理领域的文献进行梳理,旨在丰富和充实有关O2O供应链管理的理论研究成果,为渠道融合背景下线上线下渠道合作提供理论支撑。展开更多
基金National High Technology Research and Development Program of China(No.2006AA01Z235)
文摘IEEE 802.16 systems adopt a "semi-dynamic" allocation mechanism of channel quality indicator (CQI) channels.However,low utilization ratio of CQI channels reduces the spectrum efficiency.So we propose an adaptive management strategy of CQI channels based on an analysis model named "toy brick model" to improve the efficiency.The simulation results validate the improvement.
文摘In this paper, we propose a flexible and fairness-oriented packet scheduling approach for 3GPP UTRAN long term evolution (LTE) type packet radio systems, building on the ordinary proportional fair (PF) scheduling principle and channel quality indicator (CQI) feedback. Special emphasis is also put on practical feedback reporting mechanisms, including the effects of mobile measurement and estimation errors, reporting delays, and CQI quantization and compression. The performance of the overall scheduling and feedback re-porting process is investigated in details, in terms of cell throughput, coverage and resource allocation fairness, by using extensive quasistatic cellular system simulations in practical OFDMA system environment with frequency reuse of 1. The performance simulations show that by using the proposed modified PF ap-proach, significant coverage improvements in the order of 50% can be obtained at the expense of only 10-15% throughput loss, for all reduced feedback reporting schemes. This reflects highly improved fairness in the radio resource management (RRM) compared to other existing schedulers, without essentially com-promising the cell capacity. Furthermore, we demonstrate the improved functionality increase in radio re-source management for UE’s utilizing multi-antenna diversity receivers.
文摘With the rapid development of shipping industry,the volume of maritime logistics is also increasing.Tugboats are the first service station for ships,and the working efficiency tugboats directly affects the ship’s attendance rate and the port’s service efficiency.Some domestic ports use one-way channel design due to the limitations of geographical position and natural factors.However,due to the particularity of the channel,the ships are entering and leaving the port in a disorderly manner and the tugboats are running empty,which causes problems in the port.Therefore,the port is in urgent need of improving the cooperative dispatching ability of one-way channel and tugboats.
文摘According to the passage rules of ships in the bidirectional channel,the realistic conditions of the limited number of tugboats in the port are taken into account.This paper studies the problems faced in the integrated scheduling optimization in terms of ship arrival and departure and tugboat allocation in two-way channel.A mixed integer programming model with minimum waiting time was established,and a heuristic algorithm was designed to solve the problem.Experimental results show that the model and algorithm in this paper can effectively solve such problems and provide support for port management.
基金the financial support for this research from the National Natural Science Foundation of China(52176063)the International Science and Technology projects of Huangpu District of Guangzhou City(2020GH08)the Guangzhou Science and Technology Plan Project(201907010036)。
文摘The effective cathode flow field design can realize the internal water balance and higher current density output of proton exchange membrane fuel cells(PEMFC).Therefore,a segmented water management flow field is proposed in this study,i.e.a half separated-half coupled cathode(HSHC)flow field which has two inlets but just one outlet.A 3D numerical PEMFC model is applied to study the effect of the HSHC flow field on PEMFC performance and its operating strategy in terms of operating conditions.The study results are shown as follows:Compared with the two conventional cathode flow fields,the HSHC flow field improves the water balance along the channel and increases the current density by 17.1%at a cathode stoichiometry of 3.25.It is because the HSHC flow field can overcome the water loss at channels upstream and the water accumulation at channels downstream.The draw water phenomenon(DWP)in the HSHC flow field is observed,which is mainly affected by the water vapor pressure of channel.Based on the DWP,cooling channel inlet flow rates can be used to adjust water balance,but severe water loss should be avoided.In addition,the inlet temperature control in HSHC flow field should be that cell temperature>cathode channel inlet temperature>cooling channel inlet temperature>ambient temperatures for better water balance.
文摘自20世纪90年代以来,电子商务在全球迅猛发展并掀起一场新的商业革命。与此同时,业界不断在探索新的电子商务模式,近年来O2O(online to offline/offline to online)模式受到高度重视,并以爆棚式速度发展。O2O模式改变了原有电子商务环境下供应链的结构和特征,使供应链成员间的竞合博弈关系变得更为复杂,供应链管理的难度进一步加大。鉴于此,采用系统综述的方法,结合O2O模式的不同表现形式,从线上到线下、线下到线上、线上线下融合等3个方面对O2O供应链管理领域的文献进行梳理,旨在丰富和充实有关O2O供应链管理的理论研究成果,为渠道融合背景下线上线下渠道合作提供理论支撑。
