Spoofing attack is growing into a great potential menace to future GNSS systems and related applications,featured by its stealth.Spoofing signal can deceive victim receivers by changing ranging observ
In order to improve the positioning accuracy when the BDS signals are blocked and disturbed in complex urban environments,a WLAN-aided BDS location algorithm to fuse the location information of BDS an
With the rapid development of Global Navigation Satellite Systems (GPS,BDS,GALILEO and GLONASS),the number of available satellites is increasing.The redundancy of GNSS is enhanced.
Atomic clock time differences are most important original measurements for atomic time calculations of time keeping system,whose qualities affect the continuities and stabilities of time scales direct
Space environment is the main factor that infects the operation and the safe of the satellites.The operation of the satellite components and electronic equipment may be destroyed because of various en
Tropospheric delay is a major error source in geodetic techniques.In recent years,the Numerical Weather Models(NWMs),such as the European Centre for Medium Range Weather Forecasts(ECMWF),have been inc
The medium and short-term stability of hydrogen clocks and the medium and long-term stability of cesium clocks combine into a time-keeping clock set.This is a common practice in major time-keeping lab
建立了对铌铁合金采取化学溶解、浓缩制成熔片后应用X射线荧光光谱法测试铌铁中Al、Ti、Ta、V、Fe、Cu、Mn、Cr、Pb、Sn等成分的快速分析方法.讨论了各校正方式对测试结果的影响.结果表明,内标元素的加入对Nb的测试结果准确度并未带来改善,散射线的应用对于低含量重元素的测试效果也不理想,以理论α系数法校正基体效应,有效克服了铌铁中各元素谱线重叠与吸收增强效应的影响.
通过使用手持式X射线荧光光谱仪对铅锌矿含量进行分析,建立了矿山现场测定铅锌矿中Pb、Zn、Cu、Mo等元素的分析方法.针对现场测定铅锌矿的特点,选择直接粉末法进行检测.优化了电流、电压对测定的影响,比较了Ti、Ni等滤片的测试效果,对不同样品间的颗粒效应进行了校正.
本文从样品的分解处理、方法选择、指示剂选择等多方面进行验证得出,测定钙、镁元素使用盐酸分解样品,氨水沉淀干过滤进行测定;测定铝用硝酸、氢氟酸、高氯酸处理试样,碱分离进行络合滴定,标准偏差(SD)小于0.5%,相对标准偏差(RSD)均小于5.0%,加标回收率在96%~103%之间,弥补了此试样在没有国家标准指导的问题,解决了实验室自身分析难题,保证生产的有序进行,该方法单独作为进厂铝镁钙合金的元素检