为了有效缓解空中航路网络中大规模航空器集群排放引发的环境问题,研究提出一种基于聚合网络交通流的空中交通绿色优化方法。以航空器集群聚合形成的网络交通流为研究对象,构建空中航路网络交通流动力学模型,用以描述管制干预下网络交...为了有效缓解空中航路网络中大规模航空器集群排放引发的环境问题,研究提出一种基于聚合网络交通流的空中交通绿色优化方法。以航空器集群聚合形成的网络交通流为研究对象,构建空中航路网络交通流动力学模型,用以描述管制干预下网络交通流的动态演化行为。在此基础上,以最小化航空排放所致的全球绝对温变潜力(Absolute Global Temperature Potential, AGTP)为目标,构建空中航路网络交通流绿色优化模型。该模型的维度与大规模航空器集群数量无关,而取决于有限的空域单元数量,显著降低了建模维度。此外,为了进一步削减计算复杂度,通过引入辅助变量约束的方法,将原本的非线性规划问题转化为混合整数线性规划(Mixed-Integer Linear Programming, MILP)问题,并借助Cplex进行求解。最后,以华东区域5个高空管制扇区构成的航路网络为实例,对所提方法开展验证。实例分析结果显示:网络交通流动力学模型能够较好地描述空中交通的动态演化行为,平均推演误差为4.55%;网络交通流绿色管控模型可有效降低航空排放的环境影响,在25 a、50 a、100 a的时间影响尺度下,AGTP分别降低38.73%、47.62%、47.65%。展开更多
The circulating water system is widely used as the cooling system in the process industry,which has the characteristics of high water and power consumption,and its energy consumption level has an important impact on t...The circulating water system is widely used as the cooling system in the process industry,which has the characteristics of high water and power consumption,and its energy consumption level has an important impact on the economic performance of the whole system.Pump network and water turbine network constitute the work network of the circulating water system,that is,the fluid machinery network.Based on the previous studies,this paper proposes a stepwise method to optimize the fluid machinery network,that is,to optimize the network structure by using the recoverable pressure-head curve of the branch,and consider the recovery of adjustable resistance at the valve of each branch,so as to further reduce energy consumption and water consumption.The calculation result of the case shows that the topology structure optimization can further reduce the operation cost and the annual capital cost on the basis of the fixed structure optimization,and the total annualized cost can be reduced by 30.04%.The optimization result of different flow shows that both the pump network and the water turbine network tend to series structure at a low flow rate whereas to parallel structure at a high flow rate.展开更多
The rapid growth in demand for broadband wireless services coupled with the recent developmental work on wireless communications technology and the static allocation of the spectrum have led to the artificial scarcity...The rapid growth in demand for broadband wireless services coupled with the recent developmental work on wireless communications technology and the static allocation of the spectrum have led to the artificial scarcity of the radio spectrum. The traditional command and control model (Static allocation) of spectrum allocation policy allows for severe spectrum underutilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a hybrid access scheme based on CSMA/CA and TDMA MAC protocols for use in the TV bands. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that, the proposed schemes protect the primary user from harmful Interference from the secondary user. In terms of delay, it was found that packet arrival rates, data rates and the number of secondary users have significant effects on delay.展开更多
In metabolic network modelling, the accuracy of kinetic parameters has become more important over the last two decades. Even a small perturbation in kinetic parameters may cause major changes in a model’s response. T...In metabolic network modelling, the accuracy of kinetic parameters has become more important over the last two decades. Even a small perturbation in kinetic parameters may cause major changes in a model’s response. The focus of this study is to identify the kinetic parameters, using two distinct approaches: firstly, a One-at-a-Time Sensitivity Measure, performed on 185 kinetic parameters, which represent glycolysis, pentose phosphate, TCA cycle, gluconeogenesis, glycoxylate pathways, and acetate formation. Time profiles for sensitivity indices were calculated for each parameter. Seven kinetic parameters were found to be highly affected in the model response;secondly, particle swarm optimization was applied for kinetic parameter identification of a metabolic network model. The simulation results proved the effectiveness of the proposed method.展开更多
The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators...The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a dynamic spectrum access scheme for use in the TV bands which uses cognitive radio techniques to determine the spectrum availability. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that the proposed scheme protects the primary users from harmful interference from the secondary users. In comparison with the 802.11 MAC protocol, the scheme improves spectrum utilization by about 27% while limiting the interference imposed on the primary receiver.展开更多
文摘为了有效缓解空中航路网络中大规模航空器集群排放引发的环境问题,研究提出一种基于聚合网络交通流的空中交通绿色优化方法。以航空器集群聚合形成的网络交通流为研究对象,构建空中航路网络交通流动力学模型,用以描述管制干预下网络交通流的动态演化行为。在此基础上,以最小化航空排放所致的全球绝对温变潜力(Absolute Global Temperature Potential, AGTP)为目标,构建空中航路网络交通流绿色优化模型。该模型的维度与大规模航空器集群数量无关,而取决于有限的空域单元数量,显著降低了建模维度。此外,为了进一步削减计算复杂度,通过引入辅助变量约束的方法,将原本的非线性规划问题转化为混合整数线性规划(Mixed-Integer Linear Programming, MILP)问题,并借助Cplex进行求解。最后,以华东区域5个高空管制扇区构成的航路网络为实例,对所提方法开展验证。实例分析结果显示:网络交通流动力学模型能够较好地描述空中交通的动态演化行为,平均推演误差为4.55%;网络交通流绿色管控模型可有效降低航空排放的环境影响,在25 a、50 a、100 a的时间影响尺度下,AGTP分别降低38.73%、47.62%、47.65%。
基金Financial support from Key Research and Development Projects of Shaanxi Province(2024GX-YBXM-508)Research Fund for Young Star of Science and Technology in Shaanxi Province(2023KJXX-124)are gratefully acknowledged.
文摘The circulating water system is widely used as the cooling system in the process industry,which has the characteristics of high water and power consumption,and its energy consumption level has an important impact on the economic performance of the whole system.Pump network and water turbine network constitute the work network of the circulating water system,that is,the fluid machinery network.Based on the previous studies,this paper proposes a stepwise method to optimize the fluid machinery network,that is,to optimize the network structure by using the recoverable pressure-head curve of the branch,and consider the recovery of adjustable resistance at the valve of each branch,so as to further reduce energy consumption and water consumption.The calculation result of the case shows that the topology structure optimization can further reduce the operation cost and the annual capital cost on the basis of the fixed structure optimization,and the total annualized cost can be reduced by 30.04%.The optimization result of different flow shows that both the pump network and the water turbine network tend to series structure at a low flow rate whereas to parallel structure at a high flow rate.
文摘The rapid growth in demand for broadband wireless services coupled with the recent developmental work on wireless communications technology and the static allocation of the spectrum have led to the artificial scarcity of the radio spectrum. The traditional command and control model (Static allocation) of spectrum allocation policy allows for severe spectrum underutilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a hybrid access scheme based on CSMA/CA and TDMA MAC protocols for use in the TV bands. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that, the proposed schemes protect the primary user from harmful Interference from the secondary user. In terms of delay, it was found that packet arrival rates, data rates and the number of secondary users have significant effects on delay.
文摘In metabolic network modelling, the accuracy of kinetic parameters has become more important over the last two decades. Even a small perturbation in kinetic parameters may cause major changes in a model’s response. The focus of this study is to identify the kinetic parameters, using two distinct approaches: firstly, a One-at-a-Time Sensitivity Measure, performed on 185 kinetic parameters, which represent glycolysis, pentose phosphate, TCA cycle, gluconeogenesis, glycoxylate pathways, and acetate formation. Time profiles for sensitivity indices were calculated for each parameter. Seven kinetic parameters were found to be highly affected in the model response;secondly, particle swarm optimization was applied for kinetic parameter identification of a metabolic network model. The simulation results proved the effectiveness of the proposed method.
文摘The growing demand for wireless services coupled with the limited availability of suitable electromagnetic spectrum is increasing the need for more efficient RF spectrum utilization. Spectrum allocated to TV operators can potentially be shared by wireless data services, either when the primary service is switched off or by exploiting spatial reuse opportunities. This paper describes a dynamic spectrum access scheme for use in the TV bands which uses cognitive radio techniques to determine the spectrum availability. The approach allows secondary users (SU) to operate in the presence of the primary users (PU) and the OPNET simulation and modelling software has been used to model the performance of the scheme. An analysis of the results shows that the proposed scheme protects the primary users from harmful interference from the secondary users. In comparison with the 802.11 MAC protocol, the scheme improves spectrum utilization by about 27% while limiting the interference imposed on the primary receiver.
