To evaluate transmission rate of highly dynamic space networks,a new method for studying space network capacity is proposed in this paper. Using graph theory,network capacity is defined as the maximum amount of flows ...To evaluate transmission rate of highly dynamic space networks,a new method for studying space network capacity is proposed in this paper. Using graph theory,network capacity is defined as the maximum amount of flows ground stations can receive per unit time. Combined with a hybrid constellation model,network capacity is calculated and further analyzed for practical cases. Simulation results show that network capacity will increase to different extents as link capacity,minimum ground elevation constraint and satellite onboard processing capability change. Considering the efficiency and reliability of communication networks,how to scientifically design satellite networks is also discussed.展开更多
Space information network is used for real time acquiring, transmitting and processing the space information on the space platform, which provides significant communication services for communication, navigation posit...Space information network is used for real time acquiring, transmitting and processing the space information on the space platform, which provides significant communication services for communication, navigation positioning and science exploration. In this paper, the architecture of Software Defined Space Optical Network (SDSON) based on cloud platform is designed by means of Software Defined Optical Network (SDON) and cloud services. The new architecture combining centralized and distributed management-control mechanism is a multi-layer and multi-domain architecture with powerful computing and storage ability. Moreover, reliable service and unreliable service communication models employed in the space information network are proposed considering the characteristic of Disruption/Delay Tolerant Network (DTN). Finally, the functional verification and demonstration are performed on our optical experimental network platform.展开更多
现有复杂网络关键节点识别方法中缺少对节点本身特征的研究,存在网络拓扑信息提取不全面、特征冗余、泛化性低等问题.为了解决上述问题,本文提出一种基于图结构学习的复杂网络关键节点识别方法.首先,针对网络拓扑信息提取不全面问题,结...现有复杂网络关键节点识别方法中缺少对节点本身特征的研究,存在网络拓扑信息提取不全面、特征冗余、泛化性低等问题.为了解决上述问题,本文提出一种基于图结构学习的复杂网络关键节点识别方法.首先,针对网络拓扑信息提取不全面问题,结合复杂网络微观结构和宏观结构构造节点特征;其次,针对特征冗余问题,提出一个融合选择性状态空间模型(State Space Models)和自监督学习的节点特征提取方法;最后,针对泛化性低问题,利用图结构学习在模型训练层面优化损失函数提高分类精度.利用4个公开数据集上进行了广泛实验,本文方法优于次优方法4.66%,节点分辨率保持稳定.实验表明,所提出方法能有效的识别不同网络的关键节点.展开更多
随着分布式新能源、可控资源等新型元素接入配电网,传统状态估计模型面临量测信息不全、配电网拓扑变化频繁和负荷时序性波动等新问题,模型估计精度降低。针对该问题,文中提出一种融合改进生成对抗与图注意力网络的配电网状态估计方法...随着分布式新能源、可控资源等新型元素接入配电网,传统状态估计模型面临量测信息不全、配电网拓扑变化频繁和负荷时序性波动等新问题,模型估计精度降低。针对该问题,文中提出一种融合改进生成对抗与图注意力网络的配电网状态估计方法。首先,选取不同的历史时间断面,利用拓扑参数和量测信息生成数据集,通过将双向长短期记忆网络引入生成对抗网络填补数据中的缺失量测信息;其次,利用图注意力网络自适应地捕捉节点间的空间动态关系,利用双向长短期记忆(bidirectional long short-term memory,BiLSTM)网络充分挖掘不同时间断面序列信息的时间耦合关系,拼接形成关于量测量到状态量的时空特征表达,得到改进图神经网络状态估计模型;最后,在IEEE 118节点系统中进行仿真实验,并与卷积神经网络、图注意力网络等算法进行对比。结果表明,文中所提算法在数据缺失和拓扑时变情况下具有更优的估计效果。展开更多
【目的】随志愿者地理信息系统的快速发展,高现势性众源路网已成为智慧城市建设的重要数据来源,其选取的效率与效果成为影响多尺度数据服务的关键因素。已有的路网选取方法大多基于数据属性信息判断道路重要性,十分合理且有效,但是,实...【目的】随志愿者地理信息系统的快速发展,高现势性众源路网已成为智慧城市建设的重要数据来源,其选取的效率与效果成为影响多尺度数据服务的关键因素。已有的路网选取方法大多基于数据属性信息判断道路重要性,十分合理且有效,但是,实际数据往往存在属性缺失问题,一定程度上限制了方法的适用性。【方法】针对此问题,本文提出一种属性信息缺失条件下的众源路网空间句法自动建模与选取方法。首先,基于开放街道地图(Open Street Map)中心线数据,开发程序自动执行几何化简、拓扑修正与伪节点处理,批量生成整个城市的空间句法线段模型,并基于模型计算整合度、选择度等空间句法指标;随后构建Stroke,并提取几何特征;进一步,创新性地提出2项复合指标:基于路径单元的标准化角度整合度(SNAIN)与基于路径单元的标准化角度选择度(SNACH),以联合刻画道路的拓扑可达性与几何连续性。在此基础上,应用结合熵权法与层次分析法(EW-AHP)的主客观集成赋权方法,确定综合指标的权重,实现道路的重要性排序。最后,通过断头路识别与网格密度修补,进一步提高路网的连通性和完整性。【结果】以兰州(带状道路网)和成都(环形放射状道路网)为案例验证,结果表明:在道路属性信息缺失的条件下,本文方法能够有效识别城市主干路网,其与OSM道路等级匹配准确率分别达到兰州0.9421、成都0.9711;修补后兰州市路网连通率由1.0582提升至1.0864,成都市路网连通率由1.1086提升至1.1198(成都在所选尺度内的断头路完全消除)。消融实验表明,SNAIN更有利于提升全局连通性,SNACH有助于增强几何连续性,二者并用能在连通性与空间覆盖间取得平衡。【结论】本文方法为属性信息不完整情形下的大规模城市路网快速建模与选取提供了新的理论支持和技术路径。展开更多
Hyperstatic structure plane model being built by structural mechanics is studied. Space model precisely reflected in real stress of the structure is built by finite element method （FEM） analysis commerce software. M...Hyperstatic structure plane model being built by structural mechanics is studied. Space model precisely reflected in real stress of the structure is built by finite element method （FEM） analysis commerce software. Mapping model of complex structure system is set up, with convenient calculation just as in plane model and comprehensive information as in space model. Plane model and space model are calculated under the same working condition. Plane model modular construction inner force is considered as input data; Space model modular construction inner force is considered as output data. Thus specimen is built on input data and output dam. Character and affiliation are extracted through training specimen, with the employment of nonlinear mapping capability of the artificial neural network. Mapping model with interpolation and extrpolation is gained, laying the foundation for optimum design. The steel structure of high-layer parking system （SSHLPS） is calculated as an instance. A three-layer back-propagation （BP） net including one hidden layer is constructed with nine input nodes and eight output nodes for a five-layer SSHLPS. The three-layer structure optimization result through the mapping model interpolation contrasts with integrity re-analysis, and seven layers structure through the mapping model extrpulation contrasts with integrity re-analysis. Any layer SSHLPS among 1-8 can be calculated with much accuracy. Amount of calculation can also be reduced if it is appfied into the same topological structure, with reduced distortion and assured precision.展开更多
A hybrid model that is based on the Combination of keywords and concept was put forward. The hybrid model is built on vector space model and probabilistic reasoning network. It not only can exert the advantages of key...A hybrid model that is based on the Combination of keywords and concept was put forward. The hybrid model is built on vector space model and probabilistic reasoning network. It not only can exert the advantages of keywords retrieval and concept retrieval but also can compensate for their shortcomings. Their parameters can be adjusted according to different usage in order to accept the best information retrieval result, and it has been proved by our experiments.展开更多
Training neural network to recognize targets needs a lot of samples.People usually get these samples in a non-systematic way,which can miss or overemphasize some target information.To improve this situation,a new meth...Training neural network to recognize targets needs a lot of samples.People usually get these samples in a non-systematic way,which can miss or overemphasize some target information.To improve this situation,a new method based on virtual model and invariant moments was proposed to generate training samples.The method was composed of the following steps：use computer and simulation software to build target object＇s virtual model and then simulate the environment,light condition,camera parameter,etc.;rotate the model by spin and nutation of inclination to get the image sequence by virtual camera;preprocess each image and transfer them into binary image;calculate the invariant moments for each image and get a vectors＇ sequence.The vectors＇ sequence which was proved to be complete became the training samples together with the target outputs.The simulated results showed that the proposed method could be used to recognize the real targets and improve the accuracy of target recognition effectively when the sampling interval was short enough and the circumstance simulation was close enough.展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.6137110061001093+6 种基金61401118)the Natural Science Foundation of Shandong Province(Grant No.ZR2014FP016)the Natural Scientific Research Innovation Foundation in Harbin Institute of Technology(Grant No.HIT.NSRIF.2011114HIT.NSRIF.2013136HIT.NSRIF.2016100)the Scientific Research Foundation of Harbin Institute of Technology at Weihai(Grant No.HIT(WH)201409HIT(WH)201410)
文摘To evaluate transmission rate of highly dynamic space networks,a new method for studying space network capacity is proposed in this paper. Using graph theory,network capacity is defined as the maximum amount of flows ground stations can receive per unit time. Combined with a hybrid constellation model,network capacity is calculated and further analyzed for practical cases. Simulation results show that network capacity will increase to different extents as link capacity,minimum ground elevation constraint and satellite onboard processing capability change. Considering the efficiency and reliability of communication networks,how to scientifically design satellite networks is also discussed.
文摘Space information network is used for real time acquiring, transmitting and processing the space information on the space platform, which provides significant communication services for communication, navigation positioning and science exploration. In this paper, the architecture of Software Defined Space Optical Network (SDSON) based on cloud platform is designed by means of Software Defined Optical Network (SDON) and cloud services. The new architecture combining centralized and distributed management-control mechanism is a multi-layer and multi-domain architecture with powerful computing and storage ability. Moreover, reliable service and unreliable service communication models employed in the space information network are proposed considering the characteristic of Disruption/Delay Tolerant Network (DTN). Finally, the functional verification and demonstration are performed on our optical experimental network platform.
文摘现有复杂网络关键节点识别方法中缺少对节点本身特征的研究,存在网络拓扑信息提取不全面、特征冗余、泛化性低等问题.为了解决上述问题,本文提出一种基于图结构学习的复杂网络关键节点识别方法.首先,针对网络拓扑信息提取不全面问题,结合复杂网络微观结构和宏观结构构造节点特征;其次,针对特征冗余问题,提出一个融合选择性状态空间模型(State Space Models)和自监督学习的节点特征提取方法;最后,针对泛化性低问题,利用图结构学习在模型训练层面优化损失函数提高分类精度.利用4个公开数据集上进行了广泛实验,本文方法优于次优方法4.66%,节点分辨率保持稳定.实验表明,所提出方法能有效的识别不同网络的关键节点.
文摘随着分布式新能源、可控资源等新型元素接入配电网,传统状态估计模型面临量测信息不全、配电网拓扑变化频繁和负荷时序性波动等新问题,模型估计精度降低。针对该问题,文中提出一种融合改进生成对抗与图注意力网络的配电网状态估计方法。首先,选取不同的历史时间断面,利用拓扑参数和量测信息生成数据集,通过将双向长短期记忆网络引入生成对抗网络填补数据中的缺失量测信息;其次,利用图注意力网络自适应地捕捉节点间的空间动态关系,利用双向长短期记忆(bidirectional long short-term memory,BiLSTM)网络充分挖掘不同时间断面序列信息的时间耦合关系,拼接形成关于量测量到状态量的时空特征表达,得到改进图神经网络状态估计模型;最后,在IEEE 118节点系统中进行仿真实验,并与卷积神经网络、图注意力网络等算法进行对比。结果表明,文中所提算法在数据缺失和拓扑时变情况下具有更优的估计效果。
文摘【目的】随志愿者地理信息系统的快速发展,高现势性众源路网已成为智慧城市建设的重要数据来源,其选取的效率与效果成为影响多尺度数据服务的关键因素。已有的路网选取方法大多基于数据属性信息判断道路重要性,十分合理且有效,但是,实际数据往往存在属性缺失问题,一定程度上限制了方法的适用性。【方法】针对此问题,本文提出一种属性信息缺失条件下的众源路网空间句法自动建模与选取方法。首先,基于开放街道地图(Open Street Map)中心线数据,开发程序自动执行几何化简、拓扑修正与伪节点处理,批量生成整个城市的空间句法线段模型,并基于模型计算整合度、选择度等空间句法指标;随后构建Stroke,并提取几何特征;进一步,创新性地提出2项复合指标:基于路径单元的标准化角度整合度(SNAIN)与基于路径单元的标准化角度选择度(SNACH),以联合刻画道路的拓扑可达性与几何连续性。在此基础上,应用结合熵权法与层次分析法(EW-AHP)的主客观集成赋权方法,确定综合指标的权重,实现道路的重要性排序。最后,通过断头路识别与网格密度修补,进一步提高路网的连通性和完整性。【结果】以兰州(带状道路网)和成都(环形放射状道路网)为案例验证,结果表明:在道路属性信息缺失的条件下,本文方法能够有效识别城市主干路网,其与OSM道路等级匹配准确率分别达到兰州0.9421、成都0.9711;修补后兰州市路网连通率由1.0582提升至1.0864,成都市路网连通率由1.1086提升至1.1198(成都在所选尺度内的断头路完全消除)。消融实验表明,SNAIN更有利于提升全局连通性,SNACH有助于增强几何连续性,二者并用能在连通性与空间覆盖间取得平衡。【结论】本文方法为属性信息不完整情形下的大规模城市路网快速建模与选取提供了新的理论支持和技术路径。
基金This project is supported by Provincial Natural Science Foundation of Shanxi, China (No. 20041074)Provincial Natural Science Youth Foundation of Shanxi, China (No. 20051030)Provincial Education Office Key Subject of Shanxi, China (No. 20045027-20045028)
文摘Hyperstatic structure plane model being built by structural mechanics is studied. Space model precisely reflected in real stress of the structure is built by finite element method （FEM） analysis commerce software. Mapping model of complex structure system is set up, with convenient calculation just as in plane model and comprehensive information as in space model. Plane model and space model are calculated under the same working condition. Plane model modular construction inner force is considered as input data; Space model modular construction inner force is considered as output data. Thus specimen is built on input data and output dam. Character and affiliation are extracted through training specimen, with the employment of nonlinear mapping capability of the artificial neural network. Mapping model with interpolation and extrpolation is gained, laying the foundation for optimum design. The steel structure of high-layer parking system （SSHLPS） is calculated as an instance. A three-layer back-propagation （BP） net including one hidden layer is constructed with nine input nodes and eight output nodes for a five-layer SSHLPS. The three-layer structure optimization result through the mapping model interpolation contrasts with integrity re-analysis, and seven layers structure through the mapping model extrpulation contrasts with integrity re-analysis. Any layer SSHLPS among 1-8 can be calculated with much accuracy. Amount of calculation can also be reduced if it is appfied into the same topological structure, with reduced distortion and assured precision.
文摘A hybrid model that is based on the Combination of keywords and concept was put forward. The hybrid model is built on vector space model and probabilistic reasoning network. It not only can exert the advantages of keywords retrieval and concept retrieval but also can compensate for their shortcomings. Their parameters can be adjusted according to different usage in order to accept the best information retrieval result, and it has been proved by our experiments.
基金Supported by the Ministerial Level Research Foundation(404040401)
文摘Training neural network to recognize targets needs a lot of samples.People usually get these samples in a non-systematic way,which can miss or overemphasize some target information.To improve this situation,a new method based on virtual model and invariant moments was proposed to generate training samples.The method was composed of the following steps：use computer and simulation software to build target object＇s virtual model and then simulate the environment,light condition,camera parameter,etc.;rotate the model by spin and nutation of inclination to get the image sequence by virtual camera;preprocess each image and transfer them into binary image;calculate the invariant moments for each image and get a vectors＇ sequence.The vectors＇ sequence which was proved to be complete became the training samples together with the target outputs.The simulated results showed that the proposed method could be used to recognize the real targets and improve the accuracy of target recognition effectively when the sampling interval was short enough and the circumstance simulation was close enough.
