�й���½GPS����Ĺ��켰����ѧ��������Ԫ����

????????й?????????????????????????????????????????????????????????????????????????μ??й?????α? ?????GPS???????????????????????????????:??????????????????10???????й????????????????????????10??GPS?????????????????????;?????????????????????:??????????????????????????,??????????????????????????????????????,??????????????????????黡???????????????????????????,?????????????????????????????????????????????:1)?й?????????????????????????????????????????????????????????????????????????????;2)?Щ????????????????????????????????????й??????????????????     

IERS1996规范中地球引力势模型和测量模型的改进

简要而系统地介绍ＩＥＲＳ１９９６规范采用的地球引力势模型和各种测量模型,着重叙述了其与ＩＥＲＳ１９９２标准相比所作的改进。规范用ＪＧＭ－３地球引力势模型取代ＧＥＭ－Ｔ３模型,在计算地球潮汐形变产生的附加势时展开到３阶,并考虑了地幔的滞弹效应。在测站位移的计算中,规范引入了３倍洛夫数,计及地幔的滞弹性,引入了计算冰后期回弹的ＩＣＥ－４Ｇ模型,列出了改正ＶＬＢＩ观测中天线形变改正的公式。关于地球自转和     

弱磁场及甚强磁场下奇异夸克物质Urca过程的中微子能量损失率

研究了磁场对奇异星模型中夸克直接Urca过程的中微子能量损失率的影响,首先改进了弱场条件下的近似计算方法,这一方法可以推广到其他弱作用过程．在甚强磁场下,严格地计算Urca过程的中微子能量损失率,结果显示辐射率强烈地依赖于磁场,与磁场的二次方成正比,更重要的是对温度的依赖关系不同于弱场及没有磁场时的情形．     

太阳射电望远镜远程控制系统

本文简要介绍了云南天文台１０ 米口径的太阳射电望远镜天线的远程控制系统中局域网控制和通过电话线控制的实现方案     

西北地区土壤资源特征及其开发利用与保护

在分析西北地区土壤分布规律的基础上,研究了不同类型区土壤的资源特征及其在开发利用中存在的问题,认为黄土地区土壤土质疏松、粉砂含量高、富含碳酸钙是水土流失的物质基础;干旱区广为分布的荒漠土壤资源的性能低劣、绿洲区水土资源的利用比例失调是造成土地荒漠化、土壤盐渍化的根本原因;而高原土壤的粗骨性、土层浅薄、有效肥力低则加速了草场的退化和沙漠化.提出了西北地区土壤资源的合理利用与生态环境保护相协调的途经,即搞好农田基本建设,采用旱作技术节水和合理用水,扩大林草植被,保护天然草场和林木.并认为西北土壤资源的开发利用要在充分发挥其生产潜力的同时,首先应遵循生态规律,开发与保护并重,防止土壤资源衰竭和破坏.     

变面积差动电容式传感器的研究

介绍一款变面积式差动电容传感器.该传感器借助于两路相位相差180°的激励信号源作用于两固定极,使动摆片与定摆片之间形成电场.动摆片在进行摆动的过程中,在左右两固定摆中的面积会发生相应的变化,进而会产生电容量的改变.动摆片摆动角度的大小与动摆片在定片中的面积以及电容量的大小呈线性比例关系.通过交流电桥法可测量出该电容传感器的电容量的变化所对应的电压输出,并推算出动摆片位移角度的大小.实验验证了该设计的可行性.     

Seasonal variations in fouling diatom communities on the Yantai coast

Fouling diatoms are a main component of biofilm,and play an important role in marine biofouling formation. We investigated seasonal variations in fouling diatom communities that developed on glass slides immersed in seawater,on the Yantai coast,northern Yellow Sea,China,using microscopy and molecular techniques. Studies were conducted during 2012 and 2013 over 3,7,14,and 21 days in each season. The abundance of attached diatoms and extracellular polymeric substances increased with exposure time of the slides to seawater. The lowest diatom density appeared in winter and the highest species richness and diversity were found in summer and autumn. Seasonal variation was observed in the structure of fouling diatom communities. Pennate diatoms Cylindrotheca,Nitzschia,Navicula,Amphora,Gomphonema,and Licmophora were the main fouling groups. Cylindrotheca sp. dominated in the spring. Under laboratory culture conditions,we found that Cylindrotheca grew very fast,which might account for the highest density of this diatom in spring. The lower densities in summer and autumn might result from the emergence of fouling animals and environmental factors. The Cylindrotheca sp. was identified as Cylindrotheca closterium using18 S rDNA sequencing. The colonization process of fouling diatoms and significant seasonal variation in this study depended on environmental and biological factors. Understanding the basis of fouling diatoms is essential and important for developing new antifouling techniques.