Design for the simulation of space based information network

Ongoing research is described that is focused upon modelling the space base information network and simulating its behaviours： simulation of spaced based communications and networking project. Its objective is to demonstrate the feasibility of producing a tool that can provide a performance evaluation of various eonstellation access techniques and routing policies. The architecture and design of the simulation system are explored. The algorithm of data routing and instrument scheduling in this project is described. Besides these, the key methodologies of simulating the inter-satellite link features in the data transmissions are also discussed. The performance of both instrument scheduling algorithm and routing schemes is evaluated and analyzed through extensive simulations under a typical scenario.

Interruption Tolerance Routing Strategy for Space Information Network

Frequent inter-satellite link(ISL)handovers will induce service interruption in large-scale space information networks,since traditional distributed/centralized routing strategy-based route convergence/update will consume considerable time(compared with ground networks)derived from long ISL delay and flooding between hundreds or even thousands of satellites.During the network convergence/update stage,the lack of up-to-date forwarding information may cause severe packet loss.Considering the fact that ISL handovers for close-to-earth constellation are predictable and all the ISL handover information could be stored in each satellite during the network initialization,we propose a self-update routing scheme based on open shortest path first(OSPF-SUR)to address the slow route convergence problem caused by frequent ISL handovers.First,for predictable ISL handovers,forwarding tables are updated according to locally stored ISL handover information without link state advertisement(LSA)flooding.Second,for unexpected ISL failures,flooding could be triggered to complete route convergence.In this manner,network convergence time is radically descended by avoiding unnecessary LSA flooding for predictable ISL handovers.Simulation results show that the average packet loss rate caused by ISL handovers is reduced by 90.5%and 61.3%compared with standard OSPF(with three Hello packets confirmation)and OSPF based on interface state(without three Hello packets confirmation),respectively,during a period of topology handover.And the average endto-end delay is also decreased by 47.6%,9.6%,respectively.The packet loss rate of the proposed OSPF-SUR does not change along with the increase of the frequency of topology handovers.

Hybrid Chinese Information Retrieval Model Based on the Combination of Keyword and Concept

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.

Stacked spectral feature space patch: An advanced spectral representation for precise crop classification based on convolutional neural network

Spectral and spatial features in remotely sensed data play an irreplaceable role in classifying crop types for precision agriculture. Despite the thriving establishment of the handcrafted features, designing or selecting such features valid for specific crop types requires prior knowledge and thus remains an open challenge. Convolutional neural networks(CNNs) can effectively overcome this issue with their advanced ability to generate high-level features automatically but are still inadequate in mining spectral features compared to mining spatial features. This study proposed an enhanced spectral feature called Stacked Spectral Feature Space Patch(SSFSP) for CNN-based crop classification. SSFSP is a stack of twodimensional(2 D) gridded spectral feature images that record various crop types’ spatial and intensity distribution characteristics in a 2 D feature space consisting of two spectral bands. SSFSP can be input into2 D-CNNs to support the simultaneous mining of spectral and spatial features, as the spectral features are successfully converted to 2 D images that can be processed by CNN. We tested the performance of SSFSP by using it as the input to seven CNN models and one multilayer perceptron model for crop type classification compared to using conventional spectral features as input. Using high spatial resolution hyperspectral datasets at three sites, the comparative study demonstrated that SSFSP outperforms conventional spectral features regarding classification accuracy, robustness, and training efficiency. The theoretical analysis summarizes three reasons for its excellent performance. First, SSFSP mines the spectral interrelationship with feature generality, which reduces the required number of training samples.Second, the intra-class variance can be largely reduced by grid partitioning. Third, SSFSP is a highly sparse feature, which reduces the dependence on the CNN model structure and enables early and fast convergence in model training. In conclusion, SSFSP has great potential for practical crop classification in precision agriculture.

Design and Experimental Demonstration of Software Defined Space Optical Network (SDSON) Architecture Based on Cloud Platform

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.

Information space of sensor networks:Lagrangian,energy-momentum tensor,and applications

It is a challenge to investigate the interrelationship between the geometric structure and performance of sensor networks due to the increasingly complex and diverse architecture of them.This paper presents two new formulations for the information space of sensor networks,including Lagrangian and energy–momentum tensor,which are expected to integrate sensor networks target tracking and performance evaluation from a unified perspective.The proposed method presents two geometric objects to represent the dynamic state and manifold structure of the information space of sensor networks.Based on that,the authors conduct the property analysis and target tracking of sensor networks.To the best of our knowledge,it is the first time to investigate and analyze the information energy-momentum tensor of sensor networks and evaluate the performance of sensor networks in the context of target tracking.Simulations and examples confirm the competitive performance of the proposed method.

基于GIS的青岛市绿地景观生态格局与网络构建

定量化研究绿地景观生态格局和网络构建能够为城市绿地系统和国土空间的科学规划提供理论依据与方法支撑。研究基于无线电高空测候(RS)和地理信息系统(GIS)技术,运用总体景观生态格局分析和梯度分析方法,选取12个景观指数,对沿海城市——青岛市的绿地景观生态格局从斑块类型水平和景观水平两方面进行了定量研究。结果表明:斑块类型水平上,区域绿地以大型斑块为主且占优势地位,防护绿地以大中型斑块为主,二者虽空间分布不均匀,但生态效益较好;附属绿地以中小型斑块为主,缺乏大面积绿地建设,景观破碎度高但符合公众游憩需求;公园绿地以小型斑块为主且数量较少,在城区集中分布。景观水平上,城市绿地景观类型较齐全,但整体破碎度高,中部地区景观破碎度高,南部与中北部地区绿地类型多样,景观破碎度高且景观形状较复杂。在此基础上,进而分析了青岛城市绿地景观生态格局存在的问题,提出了“一轴、三核、廊汇成网、节点密布”的城市绿地生态网络优化与构建方案,以提高各类城市绿地连接度水平,发挥绿地生态系统的整体效益。

基于网络学习空间培养高职学生信息素养策略研究——以广州体育职业技术学院为例

随着教育信息化2.0的深入推进,高职学生作为未来国家产业大军的主力来源,其信息素养状况和信息素养培养策略的有效性显得日益重要。为了更好地了解当前高职学生的信息素养状况,提升他们的信息素养水平,让其具备更强的专业核心素养和终身学习能力,以网络学习空间为研究环境,通过问卷调查的研究方式,以广州体育职业技术学院为例,了解了目前职业院校学生信息素养的现状,并分析了其主要特点;然后结合网络学习空间的独特优势,探讨了在网络学习空间环境下培养高职学生信息素养的策略。

基于通道信息不平衡度的多元经验模态分解方法

在轴承多通道振动信号中,由于多通道故障信息不平衡会导致轴承故障诊断精度降低。针对这一问题,提出了一种考虑多通道故障信息不平衡的,基于多元经验模态分解(MEMD)的轴承故障特征提取与诊断方法。首先,分析了传统MEMD随机选择映射方向的缺陷,设计了依据通道间故障信息不平衡度自适应调整映射方向的策略,使分量信号中包含更多故障信息,并基于多元模态分解结果构造了特征空间;然后,基于冗余属性投影法对多通道提取的故障特征进行了融合,得到了多通道融合的本质故障特征;最后,采用反向传播(BP)神经网络进行了故障模式识别,设计了三层神经网络结构,且使用误差反向传播法进行了参数训练,并制定了基于BP神经网络的轴承故障诊断流程。研究结果表明:改进MEMD提取特征的类边界比传统方法更加明确,说明改进方法能够提取更具代表性的故障特征;从诊断精度看,与传统多元模态分解方法、完备集成辛几何分解方法相比,改进MEMD方法的诊断准确率最高,达到了99.5%。实验结果验证了改进方法在多通道故障诊断中是可行的,且从诊断精度上看,其具有一定的先进性。

空间信息网络时变图建模方法

空间信息网络是星地融合网络中一个重要组成部分,其拓扑具有时变性和可预测性。采用一个合适的时变图模型来表征时变的空间信息网络,对于空间信息网络性能分析至关重要。首先阐述了空间信息网络的特性,然后介绍了多种空间信息网络时变图模型的建模方法,包括快照序列图、时间扩展图、存储时间聚合图和多功能时间扩展图,并且分析了它们的特征和优缺点,为6G星地融合网络的研究奠定基础,为网络性能分析提供了理论支撑。

天基信息支援体系建模与效能评估方法

针对天基信息支援体系效能评估中存在的主观性强与复杂性高的问题,提出一种基于投影梯度神经网络的天基信息支援体系效能评估方法。首先,基于国防部体系框架(Department of Defense Architecture Framework,DoDAF)视图产品与包以德循环(observation,orientation,decision,action,OODA)梳理体系作战流程,进而建立评估指标体系,并基于离散事件仿真生成效能评估数据样本。然后,基于Rosen-反向传播(back propagation,BP)神经网络构建效能评估代理模型,并通过对权重参数的限制来解决在效益型指标下评估模型难以解释的问题。最后,对仿真样本进行评估模型验证试验,结果表明所提方法在天基信息支援体系效能评估中相较于传统BP神经网络计算性能提升超过50%,能够为天基信息支援体系效能评估提供技术支撑。

2023年网络安全热点技术领域全景扫描

网络安全离不开防火墙、通信加密和身份识别等技术的支撑,而网络安全技术的每一次迭代升级,都可能因技术优势易手而引起全球网络格局的重新洗牌。正因如此,近年来各国都在积极开发和运用与网络安全有关的新兴技术,以利用先进的网络技术来为军事、经济和舆论等领域的竞争提供助力。对此,分别阐述了人工智能、零信任、云环境、太空网络和量子信息技术这5个网络安全热点技术领域在2023年的发展态势,并分析研判了新兴技术在网络安全应用领域的未来趋势。

基于高分辨率遥感影像和改进U-Net的城市绿地提取

准确掌握城市绿地的面积和空间分布对于城市园林绿化规划和管理具有重要意义。针对U-Net网络提取城市绿地存在的参数冗余和边界特征丢失等问题,本研究提出一种基于改进U-Net网络的城市绿地信息自动提取方法。该方法采用MobileNetv2作为编码部分,结合交叉熵损失函数和Dice损失函数以提高模型的泛化性并解决样本不平衡的问题。同时,引入空间通道压缩与激励模块以解决边界特征提取不准确的问题,在提高模型精度和速度的同时,降低参数量。结果表明:(1)改进的U-Net模型在城市绿地提取的精度和速度方面优于其他4种经典模型,参数量仅为6.9M;相较于原始的U-Net模型,改进后U-Net模型的mIoU提高0.63%,参数量减少77.77%,平均帧数提高2.77倍,表明该方法在显著减少模型参数的同时,仍能保持较高的精确性。(2)实际应用方面,研究部署最优模型对长沙市区的绿地进行自动提取,共提取75549个绿地图斑,面积范围从0.0001hm^(2)到706.39hm^(2)不等;分区统计结果显示,岳麓区绿地面积最大,芙蓉区最小,与目视解译结果基本一致。本研究不仅提供了一种改进城市绿地提取精度和速度的方法,而且具有一定的实用价值,为城市绿化规划和管理提供有力的数据支持。

以信息为中心的天地一体化网络分域路由机制研究

针对现有星间路由策略难以实现天地一体化网络(space-ground integrated information-centric network,SGI 2CN)中卫星拓扑高动态变化情况下多源内容高效传输的问题,提出面向多源内容的分域星间路由机制(area-divided-based inter-satellite routing mechanism,ADISR)。根据给定区域划分原则,构建基于虚拟节点的卫星网络模型。对于域内路由,根据内容源位置和缓存更新,采用基于链路状态最短路径算法和状态更新算法实现域内动态路由;对于域间路由,通过综合考虑节点和链路状态提出基于辅助图的启发式算法实现跨域数据传输。仿真结果表明,与已有路由机制相比,ADISR能解决SGI 2CN中多源多路径问题,减少网络丢包率,降低内容传播时延,提高网络吞吐量。

产品网络、信息流动与产品出口

随着经济全球化的发展以及数字经济时代的到来,贸易网络越发错综复杂,产品间信息流动不断加强且其渠道日益多样化,对企业产品的出口表现产生深刻影响。借鉴产品空间理论的最新进展,本文构建产品–地理双层空间网络下的信息流动指标,并利用我国海关贸易数据,探讨产品间信息流动对产品出口的影响。研究发现,一种产品与其他产品的信息交流加强能够促进其市场份额扩张,同时带动产品内出口企业的数量增加与企业(尤其是在位企业)平均出口规模的提升。随着产品间信息流动的加强,信息对企业生产与销售过程的赋能能够促使企业调整自身进出口边际,推动企业出口单价降低与产品质量提升。本文有助于推动国际贸易研究中产品空间网络与地理空间网络不同研究支线间的融合,为当前我国挖掘出口市场海量信息价值以赋能经济增长、构建对外开放新格局提供有益启示。

面向卫星通导遥算融合的关键技术分析

空天技术深入发展后,用户对空天系统的要求将是融合通信、遥感、导航卫星的天基信息服务系统,以向用户提供高速数据传输、直达用户的实时遥感服务、精确到厘米以内的高精度定位导航、分布式协同计算资源等服务能力,从而应用于丰富的服务场景。现有的通信、导航、遥感卫星存在软件协议和物理设施上的屏障,不能融合应用,远远不能满足天基信息服务系统的建设要求,因此,有必要研究通信、导航、遥感、计算在卫星上的融合。融合关键点是硬件和软件资源的可调度、可共享,以及高效能、高稳定性的载荷器件。基于此,深入分析面向卫星通导遥算融合的关键技术,并分析通导遥算融合的典型应用服务方式,最后通过仿真实验可验证融合后的效能提升。

基于特征子空间的SOM天基状态检测算法

在天基信息网中,资源监控系统采集到的性能指标数据量大、冗余特征较多,导致状态检测准确率低、检测时间长等问题。针对以上问题,提出了基于特征子空间的SOM状态检测算法。将特征提取算法嵌入到SOM神经网络模型中,使得网络在训练的同时提取每个类别对应的属性特征,构成状态对应的特征子空间。并利用状态的特征子空间计算特征对于类别的贡献度,优化SOM神经网络的目标函数,进而提高模型对卫星计算任务执行单元状态检测的速度与准确率。仿真了在不同状态检测模型下的检测准确率、检测灵敏度以及检测时间。结果表明,提出的状态检测模型在检测准确率、检测灵敏度以及检测时间等方面都具有较好的性能。

基于贝叶斯网络的天基信息支援装备体系作战效能评估方法

针对天基信息支援装备体系效能评估存在的问题,提出一种基于贝叶斯网络的天基信息支援装备体系作战效能评估方法。构建基于系统动力学的仿真平台获取仿真数据,采用基于搜索的贝叶斯网络结构学习算法以及期望最大化(expectaion maximization,EM)参数学习算法对数据样本进行学习构建贝叶斯网络模型,以正向推理、因果追溯推理、阶段分析推理3种方式进行作战效能分析;通过该模型深入分析海上方向远程精确打击移动舰船目标的作战场景下天基信息支援装备体系中诸多影响因素之间的相互关系与影响程度。仿真结果表明:该方法应用在天基信息支援装备体系作战效能评估具备有效性和可行性,能够为武器装备体系效能评估提供技术支撑。

信息网络结构视角下的城市空间组织模式演进

城市作为一个复杂的系统具有自然生态系统中的某些特定特征,系统能量结构和能量功能以及它们与物质、信息之间的相互关系是构成整个系统发展演化的最基本规则。信息联络模式主导了群体行为准则,成为系统内在组织构成的最基本规律,从信息网络结构视角下对城市空间结构的演进进行解读,反映了城市系统演化中信息传递及组织方式对城市空间结构组织的影响及规律。

面向未来战争的网络信息体系发展思考

文中分析了未来战争对网络信息体系发展的牵引作用,指出未来战争加速向智能化战争演进,呈现出战场疆域模糊化、作战力量无人化、体系对抗复杂化等特征,牵引网络信息体系向智能化、数字化、体系化方向演进。在此基础上,从“发展体系智能,提高网络信息体系智能化水平”“打造数字空间,拓展网络信息体系新领域”等方面提出了网络信息体系未来发展思考。