Neptune Trojans: a Revisit and a New Membertwo     

Wu Rui-jun  Zhou Lei  Zhou Li-yong 《Chinese Astronomy and Astrophysics》2019,43(2):262-277

Up to now, 17 Neptune Trojan asteroids have been detected with their orbits being well determined by continuous observations. This paper analyzes systematically their orbital dynamics. Our results show that except for two temporary members with relatively short lifespans on Trojan orbits, the vast majority of Neptune Trojans located within their orbital uncertainties may survive in the solar system age. The escaping probability of Neptune Trojans, through slow diffusion in the orbital element space in 4.5 billion years, is estimated to be ～50%. The asteroid 2012 UW177 classified as a Centaur asteroid by the IAU Minor Planet Center currently is in fact a Neptune Trojan. Numerical simulations indicate that it is librating on the tadpole-shaped orbit around the Neptune's L₄ point. It was captured into the current orbit approximately 0.23 million years ago, and will stay there for at least another 1.3 million years in the future. Its high inclination of i ≈ 54^° not only makes it the most inclined Neptune Trojan, but also makes it exhibit the complicated and interesting co-orbital transitions between the leading and trailing Trojans via the quasi-satellite orbit phase.  相似文献   

天文CMOS相机测试平台及控制系统的实现     

罗志远  许骏  刘黎明  张涛 《天文研究与技术》2019,(3):345-352

CMOS相机是一种重要的固体成像设备?随着科研级CMOS相机的性能不断提高,现已广泛应用于科研领域?新真空太阳望远镜的成像设备也使用CMOS相机?因此建立一个天文CMOS相机测试系统?对于新购CMOS相机的验收以及现有CMOS相机的定期检测和维护有十分重要的意义。介绍了CMOS相机测试平台的硬件组成,并针对实际测试中对设备控制的需求,以及利用控制器对相应的设备直接控制,提出了基于TCP/IP协议以及串口通信的设计方案?利用C#编程语言设计了一套多线程并行的控制系统软件?实现各设备在局域网内的远程并行控制。通过对设备的运行测试,结果表明,系统能良好地控制各设备的正常运行?满足测试系统集成控制的需求.  相似文献   

Assessing the performance of a large-scale irrigation system by estimations of actual evapotranspiration obtained by Landsat satellite images resampled with cubic convolution     

《International Journal of Applied Earth Observation and Geoinformation》2019

Remote sensing techniques allow monitoring the Earth surface and acquiring worthwhile information that can be used efficiently in agro-hydrological systems. Satellite images associated to computational models represent reliable resources to estimate actual evapotranspiration fluxes, ET_a, based on surface energy balance. The knowledge of ET_a and its spatial distribution is crucial for a broad range of applications at different scales, from fields to large irrigation districts. In single plots and/or in irrigation districts, linking water volumes delivered to the plots with the estimations of remote sensed ET_a can have a great potential to develop new cost-effective indicators of irrigation performance, as well as to increase water use efficiency. With the aim to assess the irrigation system performance and the opportunities to save irrigation water resources at the “SAT Llano Verde” district in Albacete, Castilla-La Mancha (Spain), the Surface Energy Balance Algorithm for Land (SEBAL) was applied on cloud-free Landsat 5 Thematic Mapper (TM) images, processed by cubic convolution resampling method, for three irrigation seasons (May to September 2006, 2007 and 2008). The model allowed quantifying instantaneous, daily, monthly and seasonal ET_a over the irrigation district. The comparison between monthly irrigation volumes distributed by each hydrant and the corresponding spatially averaged ET_a, obtained by assuming an overall efficiency of irrigation network equal to 85%, allowed the assessment of the irrigation system performance for the area served by each hydrant, as well as for the whole irrigation district. It was observed that in all the investigated years, irrigation volumes applied monthly by farmers resulted generally higher than the corresponding evapotranspiration fluxes retrieved by SEBAL, with the exception of May, in which abundant rainfall occurred. When considering the entire irrigation seasons, it was demonstrated that a considerable amount of water could have been saved in the district, respectively equal to 26.2, 28.0 and 16.4% of the total water consumption evaluated in the three years.  相似文献   

基于全过程的本科毕业设计质量评价体系构建     

何立恒  杨强  鲍其胜 《测绘通报》2019,(10):138-141

对毕业设计质量评价方法进行分析,总结出考核方式单一、成绩评定不够客观及监督检查力度小是毕业设计质量评价存在的主要问题。本文从毕业设计质量考核过程化、毕业设计成果呈现方式多样化和毕业设计质量检查制度化3方面构建教师和学生共同评价的全过程质量评价体系,为全面客观评价毕业设计质量提供参考。  相似文献   

车载移动测量系统在大比例尺地形图数学精度检测中的应用   总被引：1，自引：0，他引：1  

陆玉祥  万晓莉  常岑  朱婷婷 《测绘通报》2019,(6):109-111,125

研究了车载移动测量系统在大比例尺地形图数学精度检测中的应用。首先在小范围内对其进行了相关试验,得到其有效性后,对某市全市域的地形图进行了抽样检测;对车载移动测量检验与常规方法检验在外业数据采集、内业数据处理及存储量等几方面进行了比较,分析了车载移动测量检验方法的优劣性,为提高测绘质检效率提供了一种新方案。  相似文献   

地图审核在线审批系统分析与设计     

白敬辉 《测绘通报》2019,(7):109-113

随着互联网技术的发展和“互联网＋”业态的兴起,电子政务成为推进审批服务便民化的重要内容。地图审核作为一项行政许可,主要分为申请和受理、技术审查、审批和送达及样本备案4个业务环节。根据上述业务步骤,本文对地图审核在线审批系统的设计进行了分析,完成了系统的构建与应用,为同类型其他系统的构建提供了参考。  相似文献   

一种基于卫星遥感的临近预报方法     

刘佳 《测绘通报》2019,(3):113-115,119

中尺度对流系统(MCS)是形成强对流天气的主要原因,云团在MCS生命周期中的分裂合并问题是临近预报的难点。为解决这一问题,本文提出了FCC方法,该方法使用质心位移和FY-2卫星数据预测多个对流单体的运动轨迹。多个案例分析证明,FCC算法在MCS的各个生命周期均能进行有效的预测,包括初生、成熟和消散阶段。此外,通过列联表方法验证了所提算法的有效性。  相似文献   

GNSS转发式欺骗干扰方法的改进     

何婷 《测绘通报》2019,(4):71-74,83

针对GNSS多天线转发式欺骗干扰在实际应用中,当干扰机与目标机距离大于一定范围时,将引起目标机钟差突跳,从而易被目标机检测和识别的缺陷,提出了基于干扰机阵列的转发式欺骗干扰新方法。干扰机阵列按照正六边形网型布设,可实现目标区域的无缝覆盖,并且灵活易拓展。不论目标机位于区域的任何位置,均有一个最优干扰机能够对其实施有效干扰。为了确定相邻干扰机的最优间距,本文在干扰机阵列不同间距下对具有钟差突跳自适应检测能力的目标机的干扰有效性进行了仿真研究。结论表明,综合考虑各种约束因素,相邻干扰机最优间距为17 km,满足该条件的干扰机阵列在实施欺骗干扰过程中,不会造成目标机钟差突跳,有效解决了该干扰方式易被目标机识别的问题。  相似文献   

无人海洋测绘技术体系构建   总被引：3，自引：1，他引：2  

周立  张阳  张一  付丹丹  陈晨  魏征  冯俊俊  刘泽峰 《测绘通报》2019,(4):130-133

随着无人技术的快速发展,无人测绘的时代即将到来。本文分析了无人时代技术特征与海洋测绘发展机遇;讨论了无人海洋测绘新理念,构建了无人海洋测绘技术体系,论述了无人海洋测绘技术关键技术;展望了无人海洋测绘技术发展趋势,及其在海洋经济、海洋可持续发展中的应用前景。  相似文献   

乡村生产空间系统要素构成及运行机制研究   总被引：5，自引：3，他引：2  

周明茗  王成 《地理科学进展》2019,38(11):1655-1664

乡村生产空间系统是一个客观存在的、典型的人地关系地域系统,具有耗散结构特征。论文以系统论为指导,遵循系统科学的基本思维方法,从学理上对乡村生产空间系统的内涵及要素构成进行辨析,并围绕农村生产关系变革划分了乡村生产空间系统的演进历程,在此基础上对乡村生产空间系统的运行机制进行阐释。研究发现,乡村生产空间系统主要由基础要素(资源环境和基础设施)、核心要素(多元经营主体和乡村文化)、驱动要素(资本、技术、信息和市场)和管理要素(制度和政策)4种要素构成;依据乡村生产关系变革、经济体制变迁、城乡关系转变等规律,将新中国成立后乡村生产空间系统的演进历程划分为土地改革运动时期、农业互助合作运动时期、人民公社化运动时期和家庭联产承包责任制时期4个时期,不同时期乡村生产空间系统的要素构成、要素间的联系方式不同,乡村生产空间系统特征表现各异;乡村生产空间系统通过支撑与约束机制、竞争与合作机制以及调控与反馈机制推动自身运行发展。从要素功能、结构关系、协同等视角去审视乡村生产空间系统的运行状态、诊断系统运行的动力机制或障碍因素等,将成为未来乡村生产空间系统研究的重点。  相似文献