一种面向空基网络的动态TDMA信道分配算法

本文首先分析了空基网络的固定TDMA信道分配方式,在软件定义网络(SDN)架构的基础上提出了一种适用于空基网络业务传输的动态信道分配(Dynamic Channel Allocation,DCA)算法,将数据面与控制面分离,实现了动态规划时隙分配。最后给出的仿真结果表明,与传统的固定TDMA分配算法对比,DCA算法能够明显提升高优先级突发消息的传输效率、降低传输时延,有效地调整了流量分配,为固定信道分配算法不能完全适配空基网络流量提供了解决方法。

空基网络化信息系统发展构想研究

文中从分析美军基于丰富的实战经验提出的一系列信息化装备作战理论、系统建设及发展方向出发,系统性总结美军网络化作战体系的发展脉络,通过对未来空基网络化信息系统的整体发展进行深入研究,提出了空中机群战术战法设计、空中机群联合信息环境、通信网络融合理论与方法、电磁武器及信息武器打击链理论等四个方面思考,用于启发并指导空基网络化信息系统的顶层设计和系统研发。

空基网络化信息系统浅析

面向未来信息化条件下的联合作战和体系作战需要,文中尝试着从定义空基网络化信息系统的基本概念与内涵出发,提出空基网络化信息系统的形式化表达、架构模型和工作原理,分析研究系统设计的六项关键技术,为系统方案设计和工程实施奠定一定的设计基础。

基于BD导航卫星的空基伪卫星网络动态共视授时技术

为实现广域空基伪卫星网络的精确共视授时,提出了网内传递共视授时方法;为进一步削弱对流层延迟误差的影响,提出了卫星共视选星策略;通过分析SIN/BD组合导航系统定位误差的统计特性,在揭示授时误差与组合导航系统定位误差之间数学关系的基础上,又提出采用整网平均法用以减少动态平台定位误差的影响。仿真结果表明:传递共视方法能很好地完成大区域网络的授时,有选星策略比无选星策略的对流层延迟减少约80%,运用整网平均的方法能实现优于0.3 ns的高精度共视授时,所提方法能够大幅度提高动态共视授时的精度。

空基弹性通信网络性能分析

本文针对卫星通信拒止环境下的海上编队通信网络保障需求,提出利用空中有人和无人平台构建空基移动自组织网络,保障海上编队与岸基指挥所之间的数据持续可靠传输。本文利用基于STK和QualNet的混合仿真方法建立了空基通信网络模型,在仿真场景下评估了按需距离矢量(AODV)路由协议性能,仿真结果表明空基通信网络可作为卫星通信的弹性与冗余解决方案。

空天地一体化通信网络中地面运营商的挑战与机遇

详细分析了天基网络和空基网络的网络特性、产业发展情况。卫星与HAPS通信具有传输覆盖广、不受地理环境限制、时延抖动小、可靠性高等特性。根据不同网络的能力特性,提出了未来空天地一体化网络在应急保障通信、立体化移动通信、偏远地区公众业务和大时空尺度下的通信业务等4种场景下的应用,最后阐述了为地面运营商在未来空天地一体化通信发展进程中的挑战和机遇。

宽带网络SOQPSK突发波形

空基网络通信应用中,采用恒包络波形体制可以降低设备特别是功放的复杂度,因此高效的成形偏移四相相移键控(SOQPSK)信号非常适合于空基网络。但是机载通信中多普勒频移较大,在低信噪比和短突发条件下,SOQPSK相干接收机必须有精确的载波频率和相位同步才能获得较好的性能。针对低信噪比和短突发场景,提出了基于Turbo乘积码(TPC)编码的扩频SOQPSK宽带网络波形,并设计了导频与数据帧结构,利用译码器输出的软信息来改善载波同步的性能,通过迭代操作和联合解调、解扩,增强了系统的同步性能。仿真结果表明,在误码率为10-6时所需Eb/N0为3.65 d B,达到了波形设计指标要求。

Spatial interpolation method based on integrated RBF neural networks for estimating heavy metals in soil of a mountain region

A novel spatial interpolation method based on integrated radial basis function artificial neural networks （IRBFANNs） is proposed to provide accurate and stable predictions of heavy metals concentrations in soil at un- sampled sites in a mountain region. The IRBFANNs hybridize the advantages of the artificial neural networks and the neural networks integration approach. Three experimental projects under different sampling densities are carried out to study the performance of the proposed IRBFANNs-based interpolation method. This novel method is compared with six peer spatial interpolation methods based on the root mean square error and visual evaluation of the distribution maps of Mn elements. The experimental results show that the proposed method performs better in accuracy and stability. Moreover, the proposed method can provide more details in the spatial distribution maps than the compared interpolation methods in the cases of sparse sampling density.

Conditional Mutations in Drosophila

The aim of this study was to obtain unusual mutations called conditional. The mutations manifest in some, not all representatives of a species. Collections of these mutations in chromosomes X, 2, and 3 of Drosophila melanogaster were established. Sex of fly or chromosomal rearrangement was the conditions providing ＂manifestation-non manifestation＂ of these mutations. The mutations differ from the usual by a set of properties. The salient differences in addition to conditional manifestation include： manifestation dependence on the spatial arrangement of chromosomal material in the genome, parental effects （maternal or paternal） of the mutant, capacity for transferring the genome from stable to unstable state. It is suggested that conditional mutations are mutant variants of Drosophila regulatory genes contained by the large Genomic Regulatory Network of Drosophila. Thus, the genes of this category can be detected by using special breeding procedures, mutations of these genes have unusual manifestation.

OpenFIow-Based Control Architecture for the Mobile FreeSpace Optical Networks

Mobile free space optical networks have aroused much attention due to the ability of providing high speed connectivity over long distance using the wireless laser links,while requiring relatively high available bandwidth resource and less energy consumption.However,maintaining the network with laserlinks is quite challenging due to a number of issues,such as the link fragility,the difficulty in pointingand tracking of the link,which also raises the great difficulty in the control of the network.In this paper,we present the methodology for the deployment of the mobile freespace optical networks based on our proposed OpenFlow-based control architecture.In addition,a new routing scheme is proposed and demonstrated on the testbed based on this control architecture.Delivery ratio,average delivery delay and time complexity are given to verify the performance of the OpenFlow-based control architecture.

A traffic model of optical networks based on time-space complexity and traffic grooming

This paper researched the traffic of optical networks in time-space complexity,proposed a novel traf-fic model for complex optical networks based on traffic grooming,designed a traffic generator GTS(gener-ator based on time and space)with 'centralized+distributed' idea,and then made a simulation in Clanguage.Experiments results show that GTS can produce the virtual network topology which can changedynamically with the characteristic of scaling-free network.GTS can also groom the different traffic andtrigger them under real-time or scheduling mechanisms,generating different optical connections.Thistraffic model is convenient for the simulation of optical networks considering the traffic complexity.

Spatial Differentiation Characteristics and Driving Forces of Forest Transition:A Case Study of Zunyi City,Guizhou

Spatial differentiation in forest transition was measured in terms of space transition and function transition using the exploratory spatial data analysis method（ESDA） and data from 2004—2014 for Zunyi city,Guizhou province,China.The validity of factors affecting forest transition was analyzed by constructing radial basis function neural networks（RBFNN） based on the data processing system（DPS）.Our results will provide references for scientific understanding of the potential mechanism underlying forest transition in mountainous areas.We found that Global Moran＇s I of space transition and function transition of forest land was 0.0336 and 0.2323,respectively.This suggests a significant positive correlation in spatial distribution of space transition and function transition of forest land,and significant spatial aggregation.The Global Moran＇s I of function transition was higher than that of space transition,and the spatial aggregation characteristics of function transition were more significant than for space transition.The Global Moran＇s I at each time period tended to increase,and the spatial aggregation degree of the function transition and space transition was further enhanced.Hot and cold spots of space transition of forest land stably evolved,suggesting a minor spatial difference in forest land among different administrative units at the county level.The number of hot spots at the county level in function transition increased.Hot spots were intensively distributed at the western edge and continuously distributed in the northeast.The space transition and function transition of forest land were both greatly influenced by urbanization rate and second and third industries.The development of urbanization and industrialization was the main factor driving forest transition,suggesting a positive role of economic growth on forest transition in mountainous areas.The development of urbanization and industrialization is an effective approach to forest transition in mountainous areas.

Single cell atlas of developing mouse dental germs reveals populations of CD24^(+)and Plac8^(+)odontogenic cells

The spatiotemporal relationships in high-resolution during odontogenesis remain poorly understood.We report a cell lineage and atlas of developing mouse teeth.We performed a large-scale(92,688 cells)single cell RNA sequencing,tracing the cell trajectories during odontogenesis from embryonic days 10.5 to 16.5.Combined with an assay for transposase-accessible chromatin with high-throughput sequencing,our results suggest that mesenchymal cells show the specific transcriptome profiles to distinguish the tooth types.Subsequently,we identified key gene regulatory networks in teeth and bone formation and uncovered spatiotemporal patterns of odontogenic mesenchymal cells.CD24^(+)and Plac8^(+)cells from the mesenchyme at the bell stage were distributed in the upper half and preodontoblast layer of the dental papilla,respectively,which could individually induce nonodontogenic epithelia to form tooth-like structures.Specifically,the Plac8^(+)tissue we discovered is the smallest piece with the most homogenous cells that could induce tooth regeneration to date.Our work reveals previously unknown heterogeneity and spatiotemporal patterns of tooth germs that may lead to tooth regeneration for regenerative dentistry.