卫星天线的单片机快速对星系统     

王永军  彭涛  马银圣 《全球定位系统》2008,33(6):21-24

使用GPS接收机模块得到卫星天线所在位置的经纬度,单片机模块进行数据处理得到对星所需要的方位角、仰角,与电子罗盘测得的天线的方位角、仰角进行比较得到其差值,并用液晶显示模块将其结果全部显示出来,指导天线操作人员实现快速、准确对星。  相似文献   

山东省烟台市国土空间规划监督信息系统构建研究          下载免费PDF全文

邹敏  于成  李国庆  朱鹏军  王亮 《山东国土资源》2023,39(4):70-76

烟台市进行了国土空间规划平台的升级,发布了“烟台市国土空间规划‘一张图’实施监督信息系统”。该系统基本满足了烟台市的各项发展规划需求。本文梳理了该系统的构建过程,分析了该系统的技术特点,总结了使用方法及理论,为国土空间规划平台的应用提供借鉴。  相似文献   

青藏高原湖泊沉积物与水体细菌群落共发生网络和群落构建过程差异解析     

王丹丹  黄跃飞  杨海娇 《湖泊科学》2023,35(3):959-971

研究高原湖泊沉积物和水体细菌群落结构的差异对于水生态治理与保护具有重要的科学意义。本文选取青藏高原中东部共19个湖泊为研究对象,采集沉积物和水体样本,使用高通量测序技术和统计分析,解析湖泊沉积物和水体细菌群落结构、空间分布特征、共发生网络模式、群落构建过程的差异及其原因。研究结果表明沉积物细菌群落alpha多样性指数(Chao1指数、Shannon多样性指数、Faith’s系统发育指数和Pielou均匀度指数)均显著高于水体细菌群落。沉积物和水体细菌的优势门均为Proteobacteria(相对丰度为45.33%和41.77%),而水体细菌群落结构具有较强的空间异质性。主坐标分析和相似性分析结果表明沉积物和水体中细菌群落结构差异极显著,海拔和纬度分别是青藏高原湖泊沉积物和水体细菌群落结构变化最显著的驱动因子。沉积物和水体细菌群落均具有明显的距离衰减模式,而沉积物细菌比水体细菌群落在空间上的周转率小。采样湖泊沉积物细菌群落共发生网络复杂度和稳定性高于水体细菌。沉积物和水体细菌群落的平均归一化随机率值分别为0.24和0.72,表明确定性过程在沉积物细菌群落构建的过程中起到了重要的作用,而水...  相似文献   

CFRP加固对预制节段拼装桥墩抗震性能的影响          下载免费PDF全文

马煜  张于晔 《地震工程学报》2020,42(4):847-855

为提升预制节段拼装桥墩的抗震性能,采用碳纤维增强复合材料(CFRP)对预制节段拼装桥墩在地震中易损伤部位进行加固。基于既有试验,建立缩尺的预制节段拼装桥墩三维实体有限元模型,分析预制节段拼装桥墩在循环往复荷载情况下的恢复力特性以及破坏情况。分别采用箍筋加密和外包CFRP布对预制节段拼装桥墩底部节段进行加固,对比两种加固方式对预制节段拼装桥墩抗震性能的影响。研究结果表明,CFRP包裹桥墩底部节段能够增强桥墩整体刚度和承载能力,并且使得桥墩的刚度退化更加平缓,有利于预制节段拼装桥墩在地震作用下保持自身力学特性的稳定,确保桥梁整体的安全。  相似文献   

考虑高低温影响因素的金属密封总成性能分析     

吴继媛 《海洋工程》2020,38(1):161-168

水下井口系统环空金属密封总成设计是水下油气装备国产化核心技术之一。前期国内相关研究人员已在密封设计、密封机理等方面形成共识,但密封性能评价的全面性和准确性依旧存在不足。鉴于此,提出考虑高低温影响的金属密封总成性能评价方法,构建了“有限元分析+室内测试+无损探伤”的评价流程。评价结果显示:温度是金属密封设计及性能评价过程中不可忽略的重要影响因素;设计温度范围内,该金属密封总成的密封性能及主体结构强度满足设计要求,但仍不同程度地受到温度变化影响;相对于常规方法,该评价方法更加全面准确,可为该领域其它密封设计提供借鉴和参考。  相似文献   

触摸屏和PLC相结合的DCS控制系统在自动粉末喷涂生产线的应用     

倪晨华  程彦秋  周庆伟 《海洋技术学报》2007,26(3):87-90

文中主要介绍利用触摸屏和PLC相结合的控制方式,通过可视化的操作界面,控制整个自动粉末喷涂生产线的设计,以及触摸屏和PLC的软件编程过程。  相似文献   

Detecting the intertidal morphologic change using satellite data   总被引：3，自引：0，他引：3  

Joo-Hyung Ryu  Chang-Hwan Kim  Yoon-Kyung Lee  Joong-Sun Won  Seung-Soo Chun  Saro Lee 《Estuarine, Coastal and Shelf Science》2008,78(4):623-632

Previous research has suggested that competitive bottlenecks may exist for the Mediterranean grey mullets (Osteichthyes, Mugilidae) at the fry stage with the exotic Cyprinus carpio (Osteichthyes, Cyprinidae) playing a central role. As a consequence, the structure of grey mullet assemblages at later stages is thought to reflect previous competition as well as differences in osmoregulatory skills. This paper tests that hypothesis by examining four predictions about the relative abundance of five grey mullet species in 42 Western Mediterranean estuary sites from three areas (Aiguamolls de l'Empordà, Ebro Delta and Minorca) differing in the salinity level and occurrence of C. carpio. Field data confirmed the predictions as: (1) Liza aurata and Mugil cephalus were scarce everywhere and never dominated the assemblage; (2) Liza saliens dominated the assemblage where the salinity level was higher than 13; (3) Liza ramado always dominated the assemblage where the salinity level was lower than 13 and C. carpio was present; and (4) Chelon labrosus dominated the assemblage only where the salinity level was lower than 13 and C. carpio was absent. The catch per unit effort of C. labrosus of any size was smaller in the presence of C. carpio than where it had not been introduced, which is in agreement with the juvenile competitive bottleneck hypothesis. Discriminant analysis confirmed that the assemblage structure was linked to the salinity level and the occurrence of C. carpio for both early juveniles and late juveniles as well as adults. The data reported here reveal that the structure of grey mullet assemblages inhabiting Mediterranean estuaries is determined by salinity and competitive interactions at the fry stage.  相似文献   

导向钻进在复杂场地条件下长距离铺管工程中的应用研究          下载免费PDF全文

梁小强  张可能  彭良  刘福东 《探矿工程》2006,33(3):33-37

通过对长沙市某工程复杂场地条件下长距离非开挖导向钻进技术的应用研究，提出在类似场地条件下施工应尽量全面收集施工场地已有管线及地下构筑物资料；根据场地条件合理设计导向孔轨迹；配制钻进泥浆并合理选择泥浆添加剂；选择适合长距离拖管的拖管组件。  相似文献   

Measurement of air temperature in the presence of a large radiant flux: an assessment of passively ventilated thermometer screens   总被引：1，自引：0，他引：1  

Evyatar?ErellEmail author  Vítor?Leal  Eduardo?Maldonado 《Boundary-Layer Meteorology》2005,114(1):205-231

The energy balance of small temperature sensors was modelled to illustrate the effects of sensor characteristics, particularly size, on the accuracy of readings in the presence of strong shortwave or longwave radiant loads. For all but extremely small sensors, radiant exchange may lead to unacceptable errors. The common practice of using passively ventilated instrument screens was evaluated in a series of comparative measurements. The differences resulting from the use of different models of shields may be an order of magnitude greater than the error resulting from sensor calibration. In the absence of technological innovation capable of reducing the error due to radiant exchange to negligible proportions, it is suggested that a standard methodology for calibrating and labelling the error resulting from the characteristics of the screens be adopted, to allow comparison of new data with long-established records.  相似文献   

地球的重力聚点与参数椭球的地球重力学性质   总被引：9，自引：2，他引：7  

郝晓光  许厚泽  刘大杰 《测绘学报》2000,29(2):109-113

本文研究了“参数椭球”的地球重力学性质 ,在纬度 3 5°2 1′3 2″处 ,发现了地球的“重力聚点”,给出了适用于地球的“密度分布定理”、“物质流动定理”和“重力聚点定理”;为研究地球密度的整体变化 ,提供了有用的理论工具。  相似文献