The thermal band of Landsat series satellites has a spatial resolution of 60-120 m, which plays an important role in various environmental monitoring. With the release of land surface temperature (LST) product of Landsat series satellites worldwide, the validation work also begins. However, there is still a lack of validation for long time series. Taking the middle reaches of the Heihe River Basin as the study area, the Landsat 8 LST product with 31 clear and cloudless scene images from 2013 to 2016 were verified and analyzed by using the ground measured data observed by the three weather stations of Wetland Station (SD), Gobi Station (GB) and Daman Super Station (CJZ), and the Landsat 8 LST product was compared with the widely used single-channel algorithm (JMS) inversion results. The validation results show that the accuracy of both the Landsat 8 LST product and the JMS inversion results arc high,and R2 at each site is better than 0. 919. Based on the analysis of all sites,the accuracy of Landsat 8 LST product is slightly higher than the JMS.

软件定义网络依赖于可编程与可重构的概念,将在未来卫星网络发展中发挥重要作用.通过解耦控制平面和数据平面,软件定义网络方法简化了网络管理,加快了网络创新.伴随着卫星"轨道革命"的全面深化以及卫星通信需求的不断增长,对软件定义卫星网络的关注和研究正不断深入,并使其成为一种新的范式,该架构提供了灵活管理卫星网络所需的可编程性.控制器部署作为影响网络性能的关键,是构建软件定义卫星网络的基础.在现有研究中,处理时延和链路状态对网络性能的影响往往被忽略,而这可能造成控制域规划不合理并进而导致控制器负载不均衡、网络可靠性差等问题.因此,与以往工作不同,在将处理时延和链路状态纳入优化模型的基础上,提出了针对软件定义卫星网络的基于控制时延的多控制器可靠部署策略.实验结果表明,所提策略在具有合理重构开销的条件下能够明显提升网络负载均衡性能;此外,相较于对比方案,该策略使控制时延降低近35％,且增强了网络可靠性.

随着国家天地一体化信息网络重大项目的 推进,5G-低轨星座网络切片的可靠映射成为业内的研究热点.在基于软件定义网络(software-defined network,SDN)和网络功能虚拟化(network function virtualization,NFV)的5G-低轨星座集成网络架构下,将5G-低轨星座网络切片的可靠映射问题建模为一个混合整数线性规划问题.在此基础上,研究了切片请求的资源编排,进而提出了基于广度优先搜索的可靠映射算法.该算法综合考虑切片请求的可靠性阈值及虚拟网络功能(virtual network function,VNF)的资源需求,在虚拟网络映射中根据节点的可靠重要度对节点进行排序.仿真结果表明,该算法在满足可靠性阈值约束的条件下,能够最大化收益开销比,提高虚拟网络映射成功率,在切片可靠性及接受率等方面优于对比算法.

阐述了卫星遥感技术在环境保护中的应用现状,针对新乡市环境保护的具体需求,运用遥感图谱解译技术解决大面积地面固体污染源监测问题,利用大气气溶胶反演技术实现区域PM10空间态势分析.结合地面观测站实测数据,提出利用线性拟合与回归分析方法定量评价卫星遥感数据在环境保护应用的可行性,结果表明卫星遥感数据与地面站实测数据呈现高度相关性.与地面观测站以及人工现场监测相比,卫星遥感技术具有大范围、省时省力等优点,具有广阔的应用前景.但是由于大气气溶胶多变的时空特性、探测技术精度的限制及地域关键信息的缺失,气溶胶定量反演技术并不完善,需要开展进一步的研究.

基于SDN架构的5G-卫星集成网络将是提供全球覆盖和宽带通信最有潜力的方案之一.在该集成网络中,控制器和网关的有效部署是提高网络可靠性、降低时延的关键.虽然控制器和网关部署可以独立求解,但控制器与网关部署的紧耦合特性使得联合部署更有现实意义.分析并建模了5G-卫星集成网络中SDN控制器与卫星网关联合部署的问题,提出了一种基于最大化网络可靠性的控制器与网关联合部署策略,设计了基于模拟退火与粒子群的混合算法.仿真结果表明:与枚举算法、双重模拟退火算法(SASA)等现有算法相比,文中提出的算法具有更低的时间复杂性,并将进一步降低了平均控制时延,提高了网络健壮性.

With regard to the inferior techniques and low accuracy of phase center calibration of an antenna array,this paper proposes a new calibration method considering the actual antenna pointing by introducing a precise engineering surveying technique to measure the real state of antennas. First,an industrial photogrammetric system is utilized to obtain the coordinates of points on antenna panels in different postures,and the actual pointing of the mechanical axis is obtained via least-squares fitting.Then,based on this,the coordinates of antenna rotation center are obtained by seeking the intersection of mechanical axes via using the matrix method. Finally,the mechanical axis in arbitrary postures is estimated based on the inverse-angle weighting interpolation method,and the reliable phase center is obtained by moving a fixed length from the projective center along the mechanical axis. An uplink antenna array including three 3 m antennas is taken as experimental object,and all photogrammetric coordinate systems are unified by the engineering control network,with each antenna phase center precisely calibrated via the proposed method. The results of electrical signal synthesis indicate that this method can effectively overcome the influence of gravity deformation and mechanical installation error,and enhance the synthetic signal magnitude of the uplink antenna array.

目前由于毫米波及亚毫米波频段天文观测的需要,国际上新建了很多高精度的毫米波射电望远镜,发布了很多最新科学成果.如EHT最近发布黑洞成像,验证了爱因斯坦的广义相对论,参与观测的6个站点8个台站,均可在毫米波频段观测,虽然我国也为此次成果做出突出贡献,但8台望远镜均为国外研制生产,因此研制高精度的大型射电望远镜迫在眉睫.高精度的大型射电望远镜最为大型装备,涉及多个领域关键技术突破,如测角精度就是实现核心指标跟踪和指向精度至为关键的重要基础.本文根据现有科学和工程领域的最新成果和产品,从影响测角误差的因素进行分析,论证了拼接钢带光栅尺作为角度编码器的性能可以满足指标需要,为未来大口径天线设计阶段的测角方案分析和分配、预估测角精度,为降低设计和加工误差提供参考.

出于深空探测和射电天文观测的需要,天线口径不断增大,观测频段越来越高,随之而来的高精度指向的目标,也对天线伺服系统的控制精度提出很高要求,而对于大型天线,风扰极大影响天线伺服系统控制精度.自抗扰控制技术具备算法简单,不依赖模型,抗扰性好的优势,可以满足设计需要.本文针对大型天线抗风扰需求,设计了天线自抗扰伺服控制器,通过仿真验证该控制器在复杂风扰环境下的优良性能表现.

The effects of wire deformation degree,ultrasonic power,ultrasonic time and bonding pressure and other parameters on automatic bonding consistency and reliability were studied by the test method of single variable control.The effect of each parameter on automatic bonding was analyzed.The reference range of automatic bonding parameters was given,The bonding parameters were optimized by orthogonal test,and the results were verified by experiments.The reference range of the automatic bonding of different substrates is given,which has a certain guiding significance for the automatic bonding process.

SEMWD-2000电磁波无线随钻测量系统是应用在钻井工程定向服务过程中的一种新型的无线测量设备,此系统中井下设备与地面设备通过电磁波的通信方式进行井下测量数据的传输,数据测量的实时性更高、数据传输更快、钻井液不影响设备等优点,一定程度上减少了钻井队的配合工作,同时也提高了钻井时效.此文从不同角度阐述在应用中SEMWD-2000电磁波无线随钻测量系统相对于正负脉冲式无线随钻测量设备的优势.

随着信息网络化程度的不断深入,WEB信息发布逐渐成为各类软件系统必备的功能.目前,钻井现场各类软件系统大多数仍为单机版本或较为封闭的多机版本,如何完成系统升级、实现更大范围、更快捷方便的WEB信息共享成为当务之急.Intemet COM组件作为一项新的数据交互技术,提供了本地系统与WEB服务器之间的数据交互功能.文章首先介绍了InternetCOM组件的基本概念与功能,其次通过其在钻井工程预警信息发布系统中的应用演示了Internet COM组件的设计、开发与测试.

WITSML作为新一代井场信息传输标准,采用XML技术定义数据格式,在数据结构灵活性、跨平台兼容性方面具有较强的优势.WITSML文档的数据格式同XML文档一样由相应的数据模式定义和验证,以此来保障数据传输与交换过程的顺利完成.通过对XML数据模式相关概念的介绍,分析了WITSML数据模式的组成部分和数据类型,并以面向录井信息应用的“mudLog”数据对象为例,介绍“mudLog”数据对象各个数据组件的树型层次关系,解析WITSML数据模式文档的元素、类型、嵌套包含关系及应用方式,就录井信息的WITSML标准化工作进行了初步的探讨.通过对WITSML数据模式的分析,制定企业对外数据接口和信息交换标准,简化数据交换中间环节,进而实现大范围的信息共享.

即时通讯技术作为网络技术的一个重要方向,无论在日常生活中还是在企业商用领域均得到了广泛的应用.本文首先对即时通讯技术架构与功能进行了总结,其次列举对比了市面上主流商用远程即时通讯产品特点,在此基础上分析了即时通讯技术在石油勘探开发领域中的应用方向,并针对两种不同的开发模式提出了建议.

DF cooperative communication system based on directional antenna is studied. Several different directional DF cooperative communication methods are proposed. Through the analysis of these communication methods,the expressions of the outage probabilities are derived,and the difference of the outage probabilities are compared by simulation. The results show that directional DF system with feedback and selection can obtain full diversity gains. Directional DF system with feedback is of the optimal outage performance when spectral efficiency is not high enough.

To adapt to the needs of the well site data sharing,different types of imported comprehensive mud logging units provided real-time data transmission software that met the WITS standard,but the software with different features and data interface settings were not unified to achieve uniform requirements with their real-time data output format,and which brought some inconvenience about data receiving and using.To solve this problem,on the basis of WITS characteristics,the paper analyzed WITS real-time data transmission ways,the software settings,the components of the data receiver system and the primary means to achieve real-time data receiving of 3 leading different types of imported comprehensive mud logging units(Advantage,ALS 2.2 and Datalog).Thus the authors confirmed that the real-time data transmission and reception which takes logging information-based and is in accordance with the requirements of a uniform format will safeguard real-time information sharing and making full use of.

HF is an important communication means in military communication and emergency communication.The hop-frequency and networking technique could greatly improve the anti-jamming and anti-destroying capability of HF communication.In HF networking,the channel access protocol could determine the network performance.For short wave hop-frequency networking,two channel access protocols are proposed,including multi-channel fixed slot TDMA protocol and alternate channel TDMA protocol,and these two protocols are,modeled and simulated with OPNET Modeler.The processing and analyzing of the simulation data indicates that the performance of these two TDMA protocols could be applied in short wave hop-frequency networking.

The paper presents the importance and prospects of Low Density Parity Check(LDPC) codes for application in deep space equipment.The coding methods used in NASA's all kinds of exploring missions are introduced.The comparison of Turbo and LDPC as well as other coding methods is also given with respect to their roles played in deep space application.Finally,LDPC encoding and decoding methods suitable for deep space exploration are given,and the optimization approaches for the encoding and decoding implementation circuits are provided.

High Al content AlGaN was grown on(0001)sapphire substrate by MOCVD,and AlGaN based solar-blind pin UV photodetector was developed.The fabrication processing of the device was introduced.The current-voltage characteristics and spectral responsivity of the diodes were measured to characterize their optoelectronic performance.Measurement results show that its turn-on voltage is about 4.6 V,the dark current is about 15 nA at-10 V bias voltage;the peak responsivity wavelength is 275 nm,and rejection ratio of UVC/UVB is about 103.

Time domain methods are popular and efficient in computational electromagnetics. This paper begins with a brief overview of the principles and characteristics of typical methods.On the basis of that it provides a summary of relevant hybrid methods,and then puts the emphasis on the application of signal processing techniques in time domain methods.Finally,the authors express the challenges confronted and the future anticipated in this research field.

自动链路建立(ALE)是短波通信的重要环节.ALE通过链路质量分析算法,对扫描的信道进行打分并存储,在此基础上选择信道,进行点到点和点到多点的通信,并及时更新链路质量数据.但是在协议的研究模拟中,由于系统复杂,涉及电台硬件多,调试相当困难.提出了一种通过计算机声卡传输ALE信号的解决方式,给出了硬件和软件环境,克服了仿真调试环境困难的情况.