Communication networks have undergone rapid developments in the past few decades in many Sub-Saharan African countries. The increasing number of subscribers and demand for greater variety of services in these countrie...Communication networks have undergone rapid developments in the past few decades in many Sub-Saharan African countries. The increasing number of subscribers and demand for greater variety of services in these countries make it difficult for network operators to provide the service varieties subscribers want while maintaining acceptable levels of quality of service. This paper analyzes the radio network of cellular networks in terms of traffic distribution over the existing number of communication channels using MATLAB/Simulink. A scale-free user network, which takes into account user behavior in a realistic physical network, has been used to model a more realistic cause for call blockings in a typical cellular network deployment under a Sub-Saharan environment. Peak recorded traffic distribution was observed to have overwhelmed the existing number of channels provided by the network operators for some cells eventually leading to increase in call drop rates. This high call blocking probability was attributed to poor network monitoring by the network operators to match the ever changing traffic intensities.展开更多
【目的】“双碳”目标下,中国天然气需求在2040年前仍将保持较快增长速度,天然气管网规模将进一步扩大。以往天然气管网规划布局侧重局部资源与市场点对点匹配,对于全国市场需求分布与资源统筹优化配置考虑不足,难以适应“全国一张网”...【目的】“双碳”目标下,中国天然气需求在2040年前仍将保持较快增长速度,天然气管网规模将进一步扩大。以往天然气管网规划布局侧重局部资源与市场点对点匹配,对于全国市场需求分布与资源统筹优化配置考虑不足,难以适应“全国一张网”背景下的天然气管网规划、建设与运营,因此需建立科学、系统的方法体系,为“十五·五”与远期天然气干线管网规划布局提供参考。【方法】基于全国资源市场空间分布与已建天然气干线管网布局特征,构建“区域+通道”模式的干线管网简化模型;建立以最小周转量为优化目标,以管输能力为约束的流向流量分析方法,采用GLPK(GNU Linear Programming Kit)求解器求解各通道负荷率,基于N-1原则提出各通道负荷率上限并识别通道瓶颈;结合通道瓶颈提出多个可行的规划布局方案,建立由建设投资等因素构成的综合评价指标体系,以综合成本最低为导向确定最优规划布局方案。【结果】基于2040年天然气供需预测数据开展流向流量分析,识别出已建天然气干线管网主要存在4个瓶颈,提出3种可行的规划布局方案,通过综合比选确定未来中国需要在Ⅰ、Ⅲ、Ⅵ、Ⅷ等通道进行规划布局。【结论】通过建立“区域+通道”模式的干线管网简化模型能够聚焦天然气资源配置核心问题,为优化管网输送方案提供支撑;构建基于N-1原则的瓶颈识别准则与以综合成本为导向的综合比选方法为规划布局提供了主要依据,进而建立了一套科学、系统的天然气管网规划布局方法体系。该体系能够实现在保障国家能源安全与民生用气需求的前提下,发挥有效投资的关键作用,降低管网运行能耗,为中长期天然气干线管网规划与建设决策提供参考。展开更多
文摘Communication networks have undergone rapid developments in the past few decades in many Sub-Saharan African countries. The increasing number of subscribers and demand for greater variety of services in these countries make it difficult for network operators to provide the service varieties subscribers want while maintaining acceptable levels of quality of service. This paper analyzes the radio network of cellular networks in terms of traffic distribution over the existing number of communication channels using MATLAB/Simulink. A scale-free user network, which takes into account user behavior in a realistic physical network, has been used to model a more realistic cause for call blockings in a typical cellular network deployment under a Sub-Saharan environment. Peak recorded traffic distribution was observed to have overwhelmed the existing number of channels provided by the network operators for some cells eventually leading to increase in call drop rates. This high call blocking probability was attributed to poor network monitoring by the network operators to match the ever changing traffic intensities.
文摘【目的】“双碳”目标下,中国天然气需求在2040年前仍将保持较快增长速度,天然气管网规模将进一步扩大。以往天然气管网规划布局侧重局部资源与市场点对点匹配,对于全国市场需求分布与资源统筹优化配置考虑不足,难以适应“全国一张网”背景下的天然气管网规划、建设与运营,因此需建立科学、系统的方法体系,为“十五·五”与远期天然气干线管网规划布局提供参考。【方法】基于全国资源市场空间分布与已建天然气干线管网布局特征,构建“区域+通道”模式的干线管网简化模型;建立以最小周转量为优化目标,以管输能力为约束的流向流量分析方法,采用GLPK(GNU Linear Programming Kit)求解器求解各通道负荷率,基于N-1原则提出各通道负荷率上限并识别通道瓶颈;结合通道瓶颈提出多个可行的规划布局方案,建立由建设投资等因素构成的综合评价指标体系,以综合成本最低为导向确定最优规划布局方案。【结果】基于2040年天然气供需预测数据开展流向流量分析,识别出已建天然气干线管网主要存在4个瓶颈,提出3种可行的规划布局方案,通过综合比选确定未来中国需要在Ⅰ、Ⅲ、Ⅵ、Ⅷ等通道进行规划布局。【结论】通过建立“区域+通道”模式的干线管网简化模型能够聚焦天然气资源配置核心问题,为优化管网输送方案提供支撑;构建基于N-1原则的瓶颈识别准则与以综合成本为导向的综合比选方法为规划布局提供了主要依据,进而建立了一套科学、系统的天然气管网规划布局方法体系。该体系能够实现在保障国家能源安全与民生用气需求的前提下,发挥有效投资的关键作用,降低管网运行能耗,为中长期天然气干线管网规划与建设决策提供参考。
