频率稳定度时域表征的测量不确定度

本文介绍了频率稳定度时域测量中最基本的一种方法 ,即频差倍增法 ,并详细分析了测量不确定度的来源及其算法。     

频率稳定度时域表征的测量不确定度

本文介绍了频率稳定时域测量中最基本的一种方法，即频差倍增法，并详细分析了测量不确定度的来源及其算法。     

测量重复性与建标报告中的不确定度

由国际标准化组织公布的“测量不确定度表达指南”在全国范围的宣贯已经开展很长时间了 ,其影响也日渐突出。《中国计量》杂志连续刊登关于测量不确定度理论及应用方面的文章 ,学习起来受益不浅。但是在如何分析建标技术报告中有一个问题分岐仍较大 ,即是否将被校准仪器的重复性引入计量标准的不确定度。测量结果的重复性是测量学中常用的一个术语 ,其定义为“在实际相同条件下（如用同一方法、同一观测者、同一计量器具、同一实验室内 ,于很短时间间隔内）对同一被测的量进行多次测量时 ,其测得值之间的一致程度 ,可用Ｓ（标准偏差）表示”…     

互感器测量不确定度评定在建标过程中的应用

依据JJF 1033—2008《计量标准考核规范》、JJF 1059—1999《测量不确定度评定与表示》,标准电流互感器在建标过程中,需利用其各项技术指标,对测量结果进行不确定度评定。文章通过实例着重分析了标准电流互感器各不确定度分量,建立了评定测量结果不确定度的数学模型,并计算电流互感器测量结果的扩展不确定度。     

240g/m2进口白卡纸定量的不确定度的评定

本文分析烟用印刷240g/m2进口白卡纸张定量不确定度的主要来源,满足GB/T 451.2-2002《纸和纸板定量的测定》,对样品进行处理后,根据JJF1059.1-2012《测量不确定度的评定与表示》,通过电子分析天平与定量取样器进行实验后,得出了定量不确定度的评定步骤和方法,从而给出评定结果。     

酶标分析仪吸光度准确度测量结果的不确定度评定

本文运用测量不确定度评定与表示方法,对酶标分析仪吸光度准确度测量结果的不确定度进行了评定.     

建标技术报告中不确定度分析的数学研究

文章结合实验室建标的实际情况,主要针对建标过程中不确定度评定进行分析,探究在建标报告中进行不确定度分析背后隐藏的数学意义。     

酶标分析仪吸光度测量值的不确定度的评定

本文介绍了在酶标分析仪吸光度的测量工作中的方法,相关规程的测量及描述不确定度的评定与表示。     

酶标分析仪吸光度的测量不确定度评定

本文根据酶标分析仪的检定规程,运用测量不确定度评定与表示方法,对酶标分析仪吸光度测量结果的不确定度进行分析和评定     

计量建标技术报告中测量不确定度评定的探讨

计量建标技术报告中的测量不确定度评定目前在基层计量检定机构及已建立和待建立计量标准的工矿企业计量室来说是一个不可避免而且十分重要的工作,也是基层专业人员对一项标准的建立或一次测量(测试)如何进行不确定度的评定感到比较不好把握的工作.本人结合对JJF1033-2008<计量标准考核规范>、JJF1059-1999<测量不确定度评定与表示>技术规范的理解、在撰写建标技术报告及不确定度评定过程中遇到的问题来进行一些探讨.     

钙离子光频标钟跃迁绝对频率测量

回顾了中国科学院精密测量科学与技术创新研究院对钙离子光频标钟跃迁绝对频率的测量工作，并对测量结果被国际计量委员会（CIPM）下属的时间频率咨询委员会（CCTF）采纳的情况进行了总结和描述。在2011～2020年间，利用实验室型光频标和可搬运光钟，采用基于飞秒光梳和卫星链路的方案溯源到国际秒定义，及基于飞秒光梳直接溯源到中国计量科学研究院铯喷泉微波钟的方案，多次测量了钙离子光频标钟跃迁绝对频率，测量不确定度从10^-15量级逐步提高到10^-16量级，共计4个测量结果被CCTF采纳。参与钙离子光频标钟跃迁频率国际推荐值的计算，分别于2012年、2015年、2017年和2021年先后四次更新了钙离子光频标钟跃迁频率推荐值。钙离子光频标钟跃迁于2021年被推荐为新增的“秒的次级表示”。     

Measurements of a deep space station fractional frequency stabilityto the 10-15 level

Techniques are presented for measuring the frequency stability of a deep space station that was configured with a new X-band transmitter subsystem to enable high-quality radio science data to be obtained for the gravity wave experiment. The instrument and test procedures for performing frequency stability measurements in the field are described. Test results from measurements made on various transmit and receive subsystems and the overall transmit-receive end-to-end systems below the antenna feed horn are presented. The subsystem test data proved to be useful for assessing the frequency stabilities of various subsystems. This assessment led to design improvements needed to meet stringent frequency stability requirements for forthcoming gravity wave experiments     

Na+,Ca2+和Al3+对聚丙烯酸钠的自组装行为的影响

采用荧光探针、动态光散射和透射电子显微镜研究了NaCl、CaCl<'2>和AlCl<.3>对水溶液中的聚丙烯酸钠(PAANa)自组装行为的影响.实验结果表明,在含有NaCl的聚丙烯酸钠水溶液中,分子链以线团形式存在;而Ca<'2+>或Al<'3+>与聚丙烯酸钠主链间通过静电相互作用自组装形成疏水胶束.当Ca<'2+>/...     

超声波提取-离子色谱法同时测定卷烟纸中的钾、钠、钙、镁

用0.02mol/L的盐酸溶液超声提取卷烟纸样品中的钾、钠、钙、镁4种离子,并采用离子色谱法进行同时测定。Ionpac CG12A(4mm×250mm)阳离子交换柱为固定相,15mmol/L的甲烷基磺酸为流动相,电导检测器进行测定。结果表明:方法的检出限为0.02～0.69mg/kg,加标回收率为90.14%～106.1%,相对标准偏差均小于5%,结果令人满意。     

Hg+ trapped ion standard with the superconducting cavitymaser oscillator

The frequency stability of an atomic standard based on ¹⁹⁹ Hg⁺ ions confined in a hybrid RF/DC linear trap is described. The 40.5-GHz clock transition has been measured to be 17 mHz wide, representing a quality factor greater than 2×10¹². A 160-mHz line is used to steer the output of a 5-MHz crystal oscillator to obtain a stability of 2×10^-15 for 24000-s averaging times. In a separate measurement, a 37-mHz line is used to steer the output of the superconducting cavity maser oscillator to reach 1×10^-15 stability at 10000 s     

Effects of pH and initial Ca2+?H2PO4? concentration on fibroin mineralization

In the present study, the effects of pH and initial Ca²⁺−H₂PO₄ ⁻ (Ca-P) concentration on fibroin mineralization were studied. The crystal growth of calcium phosphates was regulated by regenerated silk fibroin for 8 h (at pH 4.0, 7.0 and 10.0, respectively). Meanwhile, different concentrations of Ca²⁺ were employed at a certain pH value, keeping the initial Ca-P molar ratio constant at 1.67, i.e., the stoichiometry of hydroxyapatite [Ca₁₀(PO₄)₆(OH)₂, HAP]. The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The results demonstrated that, compared to pH 4.0 and 10.0, pH 7.0 promoted the transformation of brushite (CaHPO₄·2H₂O, DCPD) to HAP. In the composites of mineralized fibroin, DCPD is the main inorganic phase at both relatively low and high pH, while HAP is the main inorganic phase at pH 7.0. Additionally, the initial Ca-P concentration does not affect the kind of inorganic phase in the synthesized mineralized fibroin, but induce to different contents of inorganic mineral and different morphology of DCPD at pH 4.0 and pH 10.0.     

Synthesis and Spectral Study of New Complexes of Eu3+, Am3+, and Cm3+ with GaMo6O18(OH)

Complexing of Am(III) with GaMo₆O₁₈(OH) ₆ ³⁻ polyanion in an aqueous solution was studied. The stability constant β of the resulting complex was estimated at 100–150 l mol⁻¹ at pH 4.0. Crystalline complexes of Eu(III) and Gd(III) [doped with 0.5–1.5% Cm(III) ion] with GaMo₆O₁₈(OH) ₆ ³⁻ polyanion were synthesized from H₂O and D₂O solutions. The luminescence spectra and lifetime were measured for the compounds at T = 295 and 77 K. The luminescence characteristics of the Eu(III) complex proved to be virtually identical to those of the previously synthesized compound EuAlMo₆O₁₈(OH)₆·xH₂O. This also concerns the luminescence of Cm³⁺-doped GdGaMo₆O₁₈(OH)₆·xH₂O complex. The results suggest identical structures of the new compounds and complexes of lanthanides with the AlMo₆O₁₈(OH) ₆ ³⁻ anion. __________ Translated from Radiokhimiya, Vol. 47, No. 6, 2005, pp. 507–511. Original Russian Text Copyright ? 2005 by Yusov, Fedoseev.     

Very high Q microwave spectroscopy on trapped171Yb+ ions: application as a frequency standard

A microwave frequency standard based on buffer-gas cooled ¹⁷¹ Yb⁺ ions confined in a linear Paul trap has been demonstrated in prototype form. The standard exhibits a fractional frequency instability characterized by an Allan deviation σ_y (τ)=3.7×10^-13τ^-1/2 for τ<3000 s. Microwave Ramsey fringes with a Q factor of 1.5×10¹³ have been observed     

等价Ca、Sr离子固溶对CaTiO3:0.002Pr3+发光特性的影响

利用高温固相反应法,制备了不同Sr/Ca比的(Ca1-xSrx)TiO30.002Pr3+(x=0～0.6)红色发光材料.荧光光谱与XRD测试结果表明所有样品均发出源于pr3+的1D2→3H4跃迁的612m红色光;发光强度与晶胞a轴均随固溶取代量x改变而连续变化,并在x=0.15的出现极值发光强度提高约三倍,a轴则最小.研究揭示除不等价离子取代产生的电荷缺陷外,等价离子取代导致的固溶结构变化也是改变发光强度的有效途径.     

Growth and crystallization of amorphous antimony films obliquely deposited in a vacuum of 10-5 Pa

The growth and crystallization of amorohous antimony (a-Sb) films deposited onto collodion were studied as a function of the oblique angle Θ of the incident vapour beam with respect to the normal to the substrate surface by both electron and optical microscopies. The crystallization thickness increases gradually from 18 to 25 nm as Θ increases from 0° to 70° and jumps to 120–130 nm at Θ = 80° while the crystallinity of the crystallized film deteriorates as Θ increases. Crystallites grown in the a-Sb film retain a disk-like shape for normal deposition and a shape that is elongated perpendicularly to the vapour beam for oblique beam for oblique deposition. When Θ = 80° however, the film remains only partially crystallized even at a thickness of 120–130 nm and the crystallite shape is irregular. It is found that these phenomena are brought about not only by the characteristic growth of the obliquely deposited film but also probably by the adsorption of the residual gases on the internal surface developed in such a film.