大力值国际关键比对的评述

介绍了0-2MN-4MN(CCM.F-K4.a)力值国际关键比对的比对方法和比对结果以及参加大力值关键比对的各国力标准机情况.     

1MN力基准机力值不确定度评估及量值比对验证

阐述了1MN力基准机力值不确定度的各物理因素和其他影响因素的误差来源,对各影响因素的不确定度分量及合成不确定度进行了评估,评估结果的力值相对扩展不确定度为6.9×10-6(k=3)。为了验证1MN力基准机的力值不确定度,进行了1 MN与100kN力基准机之间的量值比对试验,结果表明1MN与100kN力基准机各比对点的力值相对偏差小于±0.5×10-5,力值相对扩展不确定度小于1.1×10-5(k=2),1MN力基准机力值不确定度评估结果得到了验证。     

高准确度大力值比对方法的研究

由中国计量科学研究院主导的大力值（〉1MN）国内比对，为保证我国力值的准确一致和正确传递，促进我国大力值计量水平的提高起到了重要作用。为制定科学、合理的比对方法，本文对力基、标准机特性，环境温度等影响高准确度大力值比对的因素进行了分析和研究。根据试验数据和参加比对的力标准机特性，提出了大力值国内比对的试验方法。     

CCT-K7水三相点容器国际关键比对

在国际互认框架内,国家计量标准的国际等效性是通过国际计量委员会（CIPM）的咨询委员会组织的一系列国际关键比对来确定的。温度咨询委员会（CCT）委托国际计量局（BIPM）作为主导实验室组织了由20个国家实验室参加的CCT-K7水三相点容器国际关键比对。比对结果表明：这些国家基准水三相点值在0．171mK范围内一致。此外,为了减小国家实验室复现水三相点的系统差,需要进一步研究同位素组成对水三相点温度的影响以及同位素修正。     

100kN国家基准测力机

中国测试技术研究院建立的100kN国家力值基准机,是根据物体在重力中受到地球引力的原理,利用标准破码的静重来产生基准力值。本机采用直接加荷方式,破码可根据不同载荷的要求进行组合,测量范围2kN－100kN,载荷最低可以1kN为一级逐级递增或递减,操作简便且力值稳定可靠。经过历年与准确度不低于±2×10-3的同类型测力机比对,证明本机力使不确定度小于2×10－5（r=3）,由砝码质量变化带来的误差,每年小于±2×10－‘。100kN国家基准测力机的建立,与本院建立的1kN、6kN、1MN国家基准测力机共同构成了国家力值基准系列,完善了我…     

亚太地区(APMP)60Coγ射线空气比释动能的国际关键比对

中国计量科学研究院（NIM）参加由韩国KRISS实验室为主导实验室所组织的亚太地区的60Coγ射线的空气比释动能的国际关键比对活动。亚太地区共有10个国家和组织参加此次比对活动,比对采用三支传递电离室大循环方式进行,NIM的比对结果均在0.38%内吻合。     

中国三台标准测力机的比对(英文)

本文概述了我国1MN测力基准及被比对的标准测力机,介绍了力值比对所用的传递标准器、电测量装置和测量程序。比对结果表明,成都计量测试研究院1MN基准与中国计量科学研究院杠杆式标准测力机的相对偏差不超过1×10~(-4),测量的不确定度为5×10~(-5);与长城计量研究所300kN静重式标准测力机的相对偏差不超过3×10~(-5),测量的不确定度为3×10~(-5)。     

黏度量值第二次国际关键比对(CCM.V-K2)

黏度量值国际关键比对由国际计量委员会（CIPM）的质量及相关量咨询委员会（CCM）下属的黏度工作组（WGV）组织实施,每4年进行1次。由于完全符合“国家计量标准和国家计量院开具的校准证书的互认协议”（MRA）,关键比对具有很大的权威性,参加单位均为各国最高计量研究机构。     

基于均力结构60MN叠加式力值传递系统

针对60MN力标准机开展国际力值比对的需求,提出了一种带均力结构的叠加式力值传递系统。采用理论和数值模拟的方法分析了力值传递系统中的侧向力分布及均力结构对侧向力的影响,并通过实验进行了验证。结果表明,均力结构不但能减小传递到每个子传感器上的侧向力,而且能将侧向力较均匀地分配到各子传感器上,减小旋转效应对系统的影响。采用均力结构的力值传递系统能满足国际大力值比对与量值溯源的计量性能要求。     

第10届全球绝对重力仪关键比对相对重力测量

2017年10月至12月,中国计量科学研究院作为主导实验室,组织全球14个国家的计量院或其指定实验室进行了第10届全球绝对重力仪关键比对(CCM.G-K2.2017)。由于不同类型绝对重力仪参考高度不一样,此次比对相对重力测量主要实现将不同参考高度测得的绝对重力值归算到同一高度进行比较。根据比对初步结果,相对重力测量结果的合成标准不确定度优于4μGal,确保了此次比对最终结果的准确有效。     

钛合金高温疲劳性能的试验研究

开展了钛合金材料高温疲劳试验研究。试验共设计3种工况,即:200℃,0.5kN-22.5kN-0.5kN力加载循环;300℃,0.5kN-22.5kN-0.5kN力加载循环;200℃,0.5kN-30kN-0.5kN力加载循环,每种工况下分配试样数为5个~7个。引入"肖维奈准则"对试验数据进行了筛选,通过寿命分布模型的检验,得到其有效数据点遵循正态分布模型的结论。根据试验数据分析了母体在三种工况下的中值疲劳寿命以及存活率为99.9%的疲劳安全寿命估计量,为相应工程提供基础数据。     

Evaluation of the expanded relative uncertainty of NIS developed dead weight machine

Force and Material Metrology Department (FMMD) is a department within the National Institute for Standards (NIS), founded as early as 1963. The most important event achieved within the last few years at FMMD was constructing, evaluating & commissioning of Dead Weight Machines (DWMs), the Primary Standards for force measurements with ranges of 0.05–5kN, 0.5–50kN, 10–500kN, 500–1000kN and 100–5000kN. All are computerized and delivered by GTM Company except the 5kN machine which is a manually controlled machine, established through research works carried out by FMMD [1]. The FMMD was transferred to a new building which lead to dismantling the 5kN machine and re-assembling it in its new site. In addition, the machine was developed as a part of modernizing NIS force laboratory [2].This development entailed checking the design of machine main frame using finite element method, determining the gravitational acceleration in the new building, determining the air density surrounding the machine, adjusting the machine weights to enhance the accuracy associated with the measurement results, beside designing a full computerized control circuits to control the selection and application of the loads of the machine and finally estimating the relative expanded uncertainty of the machine.     

An Intercomparison of Hydrogen and Cesium Frequency Standards

Intercomparisons of average frequency and of frequency stability were made among one Hewlett-Packard 5060A cesium beam, two Varian Associates H-10 atomic hydrogen masers, and the National Bureau of Standards NBS III cesium beam designated as the United States Frequency Standard. Each of the standards displayed a white noise frequency fluctuation behavior with a transition into an approximate flicker of frequency fluctuation behavior for longer time intervals. The rms fractional frequency fluctuation between adjacent samples, ?(?, N = 2), was 6 × 10-11?-1/2 down to a flicker level of about 3×10-13 for the hp 5060A cesium beam (102 ? ? ? 104s), 1 × 10-11?-1/2 down to a flicker level of less than 1×10-13 for NBS III cesium beam (102 ? ? ? 104s), and 5×10-13?-1/2 down to a flicker level of about 1×10-14 for the H-10 hydrogen masers (1 ? ? ? 104s). The accuracy capabilities of NBS III and H-10 #4 are now 1.1×10-12 and 0.47×10-12, respectively (1? estimate). A discrepancy of only 1.1 parts in 1012 was observed between the average frequencies of the hp 5060A cesium beam and the NBS III cesium beam, with the former being higher in frequency. In terms of the frequency of the Cs133 hyperfine transition (F=4, mF = 0)?(F=3, mF = 0), defined as 9 192 631 770.0000 Hertz, the measured frequency of the H1 hyperfine transition (F=1, mF = 0) ?-F = 0, mF = 0) was vH=1 420 405 751.7864±0.0017 Hertz.     

Synthesis and bandgap oscillation of uncapped, ZnO clusters by electroporation of vesicles

A convenient preparation is reported for subnanometre size uncapped ZnO quantum dots, which permits the previously inaccessible live observation of the growth of the clusters in the molecular size regime. The preparation method utilizes electric field-induced transient pore formation (electroporation) in synthetic unilamellar vesicles. This condition allows for facile monitoring of the time-dependent UV spectra associated with the growth of the clusters which are found to initially exhibit novel, oscillating red and blue shifts of the characteristic absorption band, ultimately followed by a monotonic red shift-the latter reflecting cluster growth beyond a size of ～10??. Through a comparison of the observed oscillating transition energies with the corresponding trends found theoretically by others, the wavelengths of the sequential spectral peaks can be assigned to the (ZnO)(1) monomer (5.66?eV), dimer (ZnO)(2) (5.19?eV), (ZnO)(5) (6.21?eV), (ZnO)(12) (5.76?eV), and (ZnO)(15) (6.01?eV). Growth beyond (ZnO)(15) is associated with the customary monotonic red shift of the absorption band (5.59 and 4.95?eV). The reason for oscillation of red and blue shift of the HOMO-LUMO gaps was explained by the structural differences of Zn(i)O(i) (i = 1-15). Under the experimental conditions used, a stable system is reached after 12 days. This solution is estimated to contain 1.4 × 10(17)?(ZnO)(15) particles, each with a greatest dimension of ～10??.     

Ion-Pair Extraction of Metalloporphyrins into Acetonitrile for Determination of Copper(II)

Equilibrium study of ion-pair extraction of a cationic water-soluble porphyrin [5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin, H(2)tmpyp(4+)] and its metalloporphyrins (MP) into the acetonitrile layer, separated by addition of sodium chloride (4.00 mol dm(-)(3)) to a 1:1 (v/v) acetonitrile-water mixed solvent, was carried out to develop a new and useful method for the determination of a subnanogram amount of copper(II). M denotes Zn(2+), Cu(2+), Co(3+), Fe(3+), and Mn(3+), and P(2)(-) is porphyrinate ion. The extraction and dissociation constants of the ion-pair complexes, defined by K(ex) = [MP(ClO(4))(4)](org)[MP(4+)](aq)(-)(1)[ClO(4)(-)](aq)(-)(4), K(dis,1) = [MP(ClO(4))(3)(+)](org)[ClO(4)(-)](org)[MP(ClO(4))(4)](org)(-)(1), and K(dis,2) = [MP(ClO(4))(2)(2+)](org)[ClO(4)(-)](org)[MP(ClO(4))(3)(+)](org)(-)(1), were determined by taking into account the partition constant of sodium perchlorate (K(D) = 1.82 ± 0.01). The equilibrium constants were found to be K(ex)K(dis,1) = (7.2 ± 1.3) × 10(4), (6.4 ± 0.9) × 10(4), (1.35 ± 0.13) × 10(5), (4.8 ± 0.6) × 10(3), (1.23 ± 0.05) × 10(4), and (1.42 ± 0.07) × 10(3) at 25 °C for the free base porphyrin (H(2)tmpyp(4+)) and the metalloporphyrins of zinc(II), copper(II), cobalt(III), iron(III), and manganese(III), respectively. The K(dis,2) values were (2.9 ± 1.4) × 10(-)(2), (3.1 ± 1.1) × 10(-)(2), (8.0 ± 4.9) × 10(-)(3), and (5.1 ± 2.2) × 10(-)(2) for the free base porphyrins and the metalloporphyrins of zinc(II), copper(II), and cobalt(III), respectively. The results were developed for determination of a trace amount of copper(II) (3 × 10(-)(8)-4 × 10(-)(6) mol dm(-)(3)) in natural water samples using H(2)tmpyp(4+) with a molar absorptivity of 3.1 × 10(5) mol(-)(1) dm(3) cm(-)(1) at a precision of 1.3% (RSD). The determination of copper(II) was not interfered by the presence of 10(-)(4) mol dm(-)(3) of Mn(2+), Co(2+), Ni(2+), Hg(2+), Cd(2+), Ag(+), Cr(3+), V(5+), Al(3+), Mg(2+), Ca(2+), Br(-), I(-), SCN(-), and S(2)O(3)(2)(-) and 10(-)(5) mol dm(-)(3) of Fe(3+), Zn(2+), and Pd(2+).     

Effect of clamping force on the delamination onset and growth in bolted composite laminates

Clamping force is a key element that alters the mechanism and sequence of failure in bolted joints of composite laminates. The mode of failure in bolted joints can be controlled by geometrical parameters and the preferred fail safe mode of failure is ‘bearing’ which generally consists of matrix cracks, delamination and fibre microbuckling. Three-dimensional (3-D) pinned (without clamping force) and bolted (1 kN clamping force) joint models were developed in [0/90]_s carbon fibre reinforced plastic (CFRP) laminates to show the clamping force effect on the onset and growth of delamination. It is shown that delamination was resulted from the shear stress components (Mode II & III) at the interface and the contribution of the out-of-plane component (Mode I - opening), so the clamping force, was negligible without modelling the in-plane failure modes and their coupling with delamination, which will be considered in future work.     

附加式压磁测力传感器在动态称重轨中的应用

根据剪力型动态称重轨的工作原理,对应用附加式压磁测力传感器动态称重进行了可行性研究。设计了一种三磁极压磁测力传感器,推导出这种传感器的输出方程,并分别在材料试验机与矿山有轨运输轨道上进行了静态特性标定试验和实试验。试验结果表明,这种传感器能够达到5mV／kN的测试灵敏度和小于2．7％的不重复精度。另外,这种传感器结构简单、安装方便、坚固耐用,将其应用动态称重轨是可行的。     

On-line coupling of flow field-flow fractionation and multiangle laser light scattering for the characterization of macromolecules in aqueous solution as illustrated by sulfonated polystyrene samples

Seven sulfonated polystyrene standards (18?000-3?000?000 g/mol), taken as model substances for macromolecular polyelectrolytes, were dissolved in aqueous 0.1 M sodium nitrate solution and characterized by multiangle laser light scattering coupled on-line to flow field-flow fractionation. The distributions of molar mass and root mean square radius and the diffusion coefficients were obtained for each sample using a constant field of force for separation. Relationships between molar mass and root mean square radius [?R(G)(2)?(z)(0.5) = (2.71 × 10(-)(2))M(w)(0.56)] or diffusion coefficient [D = (7.10 × 10(-)(8))M(w)(-)(0.68)] were calculated. To investigate the static analytical range of this novel hyphenated technique a mixture of all seven samples was fractionated applying a programmed field. The relationship obtained between root mean square radius and molar mass was used to calculate a Mark-Houwink equation [[η]calcd = (2.99 × 10(-)(2))M(w)(0.68)]. To verify this result, the intrinsic viscosities for all samples were measured at low shear rate and found to be in good agreement [[η]calcd = (2.77 × 10(-)(2))M(w)(0.67)].     

Implementation of Electrochemically Synthesized Silver Nanocrystallites for the Preferential SERS Enhancement of Defect Modes on Thermally Etched Graphite Surfaces

Highly oriented pyrolytic graphite (HOPG) surfaces, on which atomically well-defined roughness has been introduced via high-temperature gasification reactions, are investigated by noncontact mode atomic force microscopy (NC-AFM) and Raman spectroscopy both before and after the electrochemical deposition of silver nanocrystallites on these surfaces. Exposure of freshly cleaved HOPG surfaces to an O(2)-rich ambient at 650 °C for a few minutes caused the formation of 1-monolayer-deep, circular etch pits on the HOPG basal plane surface. Silver nanocrystallites were electrochemically deposited onto these etched surfaces at two coverages: 0.5 mC cm(-)(2) (or 5 nmol of Ag(0) cm(-)(2)) and 2.4 mC cm(-)(2) (25 nmol of Ag(0) cm(-)(2)). At the lower coverage, NC-AFM images revealed that silver decorated only the circumference of the circular etch pits, forming a uniform annular ring with an apparent diameter of 200-250 ? and a height of ～15 ?. At the higher silver coverage, an increase in the height but not the diameter of this annulus was observed, and additional silver nanostructures [Formula: see text] having dimensions of 300-350 ? diameter and 15 ? height [Formula: see text] were observed on atomically smooth regions of the graphite basal plane. The Raman spectroscopy of these surfaces was investigated and compared with spectra for nanocrystallite-modified but unetched HOPG basal plane surfaces and thermally etched surfaces on which no silver was deposited. For for thermally etched HOPG surfaces at either silver coverage, SERS-augmented Raman spectra were obtained in which defect modes of the graphite surface [Formula: see text] derived from "finite" graphite domains at the surface [Formula: see text] were strongly and preferentially enhanced. In addition, an enhanced band near 2900 cm(-)(1) was assigned to ν(OH) from carboxylate moieties present at step edges based on the basis of the observed pH dependence of the enhancement.     

Comparison of the ocean inherent optical properties obtained from measurements and inverse modeling

A model developed recently by Loisel and Stramski [Appl. Opt. 39, 3001-3011 (2000)] for estimating the spectral absorption a(lambda), scattering b(lambda), and backscattering b(b)(lambda) coefficients in the upper ocean from the irradiance reflectance just beneath the sea surface R(lambda, z = 0(-)) and the diffuse attenuation of downwelling irradiance within the surface layer ?K(d)(lambda)?(1) is compared with measurements. Field data for this comparison were collected in different areas including off-shore and near-shore waters off southern California and around Europe. The a(lambda) and b(b)(lambda) values predicted by the model in the blue-green spectral region show generally good agreement with measurements that covered a broad range of conditions from clear oligotrophic waters to turbid coastal waters affected by river discharge. The agreement is still good if the model estimates of a(lambda) and b(b)(lambda) are based on R(lambda, z = 0(-)) used as the only input to the model available from measurements [as opposed to both R(lambda, z = 0(-)) and ?K(d)(lambda)?(1) being measured]. This particular mode of operation of the model is relevant to ocean-color remote-sensing applications. In contrast to a(lambda) and b(b)(lambda) the comparison between the modeled and the measured b(lambda) shows large discrepancies. These discrepancies are most likely attributable to significant variations in the scattering phase function of suspended particulate matter, which were not included in the development of the model.