降低可动屏蔽型计算电容端部效应误差的一个新方法(英文)

本文提出了一种降低可动屏蔽型计算电容端部效应误差的新方法:在屏蔽杆端面的一个附加电极上加上一个适当的电压,就能自动补偿电极系统不平行的影响,从而大大降低端部效应误差。这种方法与国际上流行的用钉子头补偿的方法相比,具有调节细度高、补偿效果较完善等一系列优点。计算表明,采用这种方法后,即使电极的不平行性达到2μm,仍可使端部效应误差小于1×10~(-8)。对于计算结果还用准确度约5×10~(-5)的模型实验进行了检验。文中还计算了屏蔽杆的偏心、屏蔽杆端面上的附加电极的尺寸公差、局部缺陷等一系列因素的影响。     

NIM新一代二端对电容电桥装置

基于一种交流电桥自动辅助平衡方法,中国计量科学研究院(NIM)研制了新一代二端对电容电桥装置。电桥采用固定比率的感应耦合比率臂电桥,通过复用比率,用单一电桥即实现了计算电容过渡和电容10:1传递;采用一种改进的靴带法实现电桥感应比率臂比率的精确校验。该装置用于电容单位的量值复现和标准电容器的高准度量值传递。利用新一代二端对电容电桥装置,可从计算电容装置复现1 pF电容值,并实现电容 1~100 pF的十进制量值传递,电容量值传递相对标准不确定度可达5×10^-9(1592 Hz)。采用该电桥参加了10 pF和100 pF电容国际关键比对(CCEM.K4-2017),中国比对成绩优异,数据均非常接近关键比对参考值(KCRV),其中100 pF的结果最接近KCRV,与KCRV取得了很好的一致性,从而获得国际互认。     

DSZ3级水准仪补偿误差的测量不确定度分析评定

水准仪补偿能力反映了仪器倾斜时补偿器修正竖轴倾斜量的能力,也反映了补偿器修正视准轴误差的能力。补偿误差是仪器在补偿范围内倾斜某个角度时视准线偏离置平状态时的误差,通过对影响DSZ3级水准仪补偿误差测量的因素进行分析,计算了各影响分量的标准不确定度,完成了补偿误差测量扩展不确定度的评定,评定结果可以为自动安平水准仪的使用者和检定机构提供参考。     

基于阿贝误差补偿光路的水准标尺检定装置及不确定度分析

现行有效的JJG 8——1991《水准标尺》要求以激光波长作为长度基准,使用激光干涉检定器对因瓦水准标尺进行检定。检定3 m长的水准标尺,若照准部不动而标尺移动,需要6 m长的导轨。为缩短导轨长度,降低加工难度,采用标尺固定而照准部移动的检定装置,可有效地将导轨长度由6 m缩短至3 m。由于不满足阿贝原则,检定装置设计基于阿贝误差补偿光路的结构,实现对阿贝误差的消减。该装置补偿性能的实测结果表明:利用光学补偿的方法极大地消减阿贝误差。"米间隔长度平均值"不确定度的评定结果表明:该装置可以满足水准标尺检定规程中对检定装置的相关要求。该补偿光路也可用于其他长度测量系统。     

用电校准辐射计复现发光强度单位—坎德拉

本文介绍采用锥腔补偿型电校准辐射计复现发光强度单位的实验装置、方法和结果。分析了各项误差,得到的总的不确定度为±0.28％。     

电涡流传感器非线性补偿电路设计

电涡流位移传感器输出特性非线性明显,为改善传感器线性度,需要进行输出信号的非线性补偿.通过在电涡流传感器前置电路的基础上增加非线性补偿电路模块,可以改善传感器线性度.为获得实用的线性化补偿器,根据传感器位移电压测量数据,先确定其非线性函数关系及线性补偿范围,以函数补偿法为基础采用开环补偿与闭环补偿,分别进行了非线性补偿电路设计,通过模拟电路实现了相关函数运算功能.借助电路仿真手段,可方便地确定电路的结构与具体电路参数.对实际非线性补偿电路进行了测试,实验结果表明,所设计的非线性补偿电路结构简单,能有效改善传感器的线性度.     

滚动轴承滚针直径测量结果的不确定度评定

在立式光学计上测量滚动轴承滚针直径,利用量块尺寸作为标准,将测量装置调整为零位,然后测出滚针与量块标准尺寸的差值,求出被测滚针的直径尺寸。分析了温度误差、测量力误差、示值误差、标准量块极限误差、测量重复性和测量装置定位误差等对测量装置不确定度的影响,并给出了相应的不确定度的计算公式。     

热电偶检定中电测量仪器的不确定度

电测仪器的不确定度是热电偶分度 ,检定和测量结果不确定度的重要分量。本文探讨该电测仪器不确定度的评估和计算 ,重点是相关量和附加误差的影响。所涉及内容也可供热电偶“建标”、精密测量时选择电测仪器和环境条件的参考。     

基于图像识别和GPS技术的全自动补偿式微压计的设计

传统的补偿式微压计测量采用手动测量、人眼读数的方式实现数据的获取,人眼读数误差所引入的不确定度在装置整体不确定度中占有很大比重。本文研制了一种全自动补偿式微压计,利用高清摄像头代替人眼读数,利用软件对所采集的图片进行逻辑分析,同时增加传统补偿式微压计不具备的实时液相温度测量、实地重力加速度测量及大气压测量功能,有效减小各影响量对测量结果的干扰。采用滑台电机控制位移,进一步提高测量准确度。经实验证明,本文研制的全自动补偿式微压计具有很好的准确性与可靠性。     

电容无功补偿的重要性及常见问题分析

从理论上阐述了电容无功补偿的重要性，以及对电容补偿装置的计算方法及常见问题进行了较为深入的分析。     

60Co γ辐射空气比释动能基准的研究进展和相关国际比对

60Coγ辐射空气比释动能基准是医用加速器光子水吸收剂量的重要溯源基准之一.近三年来,中国计量科学研究院(NIM)先后就60Co γ辐射空气比释动能参加了国际原子能机构(IAEA)的国际比对,以及国际计量局(BIPM)组织的新一轮的关键比对,最新的关键比对数据库(KCDB)结果表明,NIM的比对结果与国际计量研究机构及地区基准实验室的结果之间的一致性较好.     

一种由NIM5铯喷泉基准驾驭实现的独立时标TA（NIM）

原子时标TA（NIM）是一个独立时标,其频率由NIM5铯喷泉基准驾驭。产生时标的主钟是一台主动型氢原子钟,铯喷泉基准定期对其测量和校准。时标算法通过预估氢钟将来的频率,补偿过去预估频率与校准频率之差,并评估无校准数据期间的氢钟频率,最终尽可能实现TA（NIM）的频率与NIM5铯喷泉基准保持一致。2007年8月,TA（NIM）开始试运行,2008年6月正式运行。1年多来的数据分析表明,TA(NIM)运行连续可靠,与TAI间的时间稳定度(5天)达到1.2 ns,相对频差为2.0×10^-15。     

Nanoscale impedance microscopy-a characterization tool for nanoelectronic devices and circuits

A recently developed conductive atomic force microscopy (cAFM) technique, nanoscale impedance microscopy (NIM), is presented as a characterization strategy for nanoelectronic devices and circuits. NIM concurrently monitors the amplitude and phase response of the current through a cAFM tip in response to a temporally periodic applied bias. By varying the frequency of the driving potential, the resistance and reactance of conductive pathways can be quantitatively determined. Proof-of-principle experiments show 10-nm spatial resolution and ideal frequency-dependent impedance spectroscopy behavior for test circuits connected to electron beam lithographically patterned electrode arrays. Possible applications of NIM include defect detection and failure analysis testing for nanoscale integrated circuits.     

Application and exploration of nanofibrous strategy in electrode design

The key to develop high specific energy rechargeable batteries is development of new electrode materials.The existing electrode materials still have many problems: the shuttle effect and poor conductivity of the sulfur cathode,the inevitable volume expansion of the silicon anode and the lithium dendrite of the lithium metal anode that cause short circuits,etc.Nanofibers,as active electrical materials,conductive additives and electrode bodies,can play multiple roles in electrode design.More interestingly,nanofibers can be functionalized to obtain better controllable properties (i.e.,electrolyte affinity,pore size distribution and surface electronic structure),thereby further enhancing electrochemical performance.In this article,the latest research progress in electrode design based on nanofibers is reviewed,including processing methods,structure,morphology and electrochemical performance.The key problems affecting the electrochemical performance of the electrode are also discussed,such as the preparation process,atomic structure,electrical conductivity,surface area and pore distribution of nanofibers,to provide reference points for nanofibers in excellent electrode design.     

Physicochemical characterization of nimodipine–polyethylene glycol solid dispersion systems

This study investigates the solid–solid interactions between nimodipine (NIM) and polyethylene glycol (PEG) of different mean molecular weights (PEG 2000, 4000 and 6000), in solid dispersion systems, applying differential scanning calorimetry (DSC), Fourier-Transform infrared spectroscopy, powder X-ray diffraction (PXRD), hot stage microscopy (HSM) and theoretical modeling by the Flory–Huggins (FH) solution theory. Phase diagrams constructed with the aid of DSC and FH solution theory showed sensitivity on the estimated values of the FH interaction parameter (χ). When χ is considered a constant number (χ?=?α, α?≠?0), formation of a eutectic mixture is predicted in the 70–80% w/w PEG concentration region, while when χ was considered as a function of concentration and temperature (χ?=?f(φ,Τ)), the model predicts the formation of monotectic systems. Construction of more precise phase diagrams by HSM to the aid of Kofler’s “contact preparation” method confirmed the monotectic nature of the examined systems. Studies on NIM’s re-crystallization process in the solid dispersions revealed a strong dependence of the crystallization rate, as well as the resulting crystal form, on the mean molecular weight and concentration of PEG: NIM crystallization rates decrease as PEG’s MW increases, while NIM mod II crystals predominate in dispersions prepared at temperatures above NIM’s liquidus and growth of NIM mod I prevailing in PEG-rich samples.     

光谱辐射亮度国际比对与结果分析

基于高温黑体辐射源BB3500M,中国计量科学研究院(NIM)自主研制了第四代光谱辐射亮度国家基准装置,波长范围覆盖220~2550nm,以稳定的钨带灯作为传递标准,改善了测量不确定度。黑体辐射源的温度测量溯源至Pt-C和Re-C固定点黑体,在3021 K采用WC-C固定点黑体进行验证,NIM和全俄光学物理计量院(VNIIOFI)之间的测量偏差小于70 mK。采用新基准装置,NIM参加了光谱辐射亮度国际APMP-PR.S6比对。NIM研制了两套入射光学系统,成像倍率分别为0.58和1.00,立体角为0.006sr和0.008sr,采用两套系统复现光谱辐射亮度量值的差异小于±0.40%。APMP-PR.S6比对结果表明:在紫外、可见和近红外波长范围,NIM与参考值的平均相对偏差分别为0.59%、0.44%和0.34%。全部波长范围的平均相对偏差0.46%。在250nm、400nm、800nm、2500nm波长,光谱辐射亮度的测量标准不确定度分别为0.95%、0.50%、0.41%和0.80%。从而验证了第四代光谱辐射亮度国家基准装置的准确性和可靠性。     

NIM和VNIIOFI光谱辐射照度双边比对

2014年12月至2015年1月,中国计量科学研究院(NIM)采用新研制的光谱辐射照度国家基准装置,与全俄光物理测量研究院(VNIIOFI)进行了光谱辐射照度双边比对。比对的波长范围为250～2500nm, NIM和VNIIOFI的光谱辐射照度测量均基于高温黑体辐射源BB3500M,采用高温计测量黑体的温度,溯源至Pt-C和Re-C固定点黑体,并采用WC-C固定点黑体进行了验证,双方在3021K的温度一致性优于70mK。光谱辐射照度双边比对结果表明: 44个比对波长点的光谱辐射照度的平均相对偏差为0.45%。除2000nm波长点的相对偏差为1.1%外,在全波段范围内量值的一致性优于0.90%,均在声称的不确定度范围内。     

T 90 Measurement of Co-C, Pt-C, and Re-C High-Temperature Fixed Points at the NIM

The blackbodies of high-temperature fixed points (HTFPs), namely, Co-C, Pt-C, and Re-C eutectic points, were gradually established at the National Institute of Metrology (NIM) of China after 2007, and their characteristics were studied. Recently, the primary standard pyrometer was improved with the lower size-of-source effect, distance effect, and partial temperature controls. The pyrometer was characterized at the new facility for the calibration of the spectral responsivity. The measurement of its nonlinearity extended to a primary standard pyrometer (PSP) reading of approximately 2680 °C for the HTFP measurements. The International Temperature Scale of 1990 above the silver point was realized at the NIM by an improved scheme, the fixed-point blackbody pyrometer assembly. Two cells each for Co-C, Pt-C, and Re-C points were assigned associated uncertainties (k = 2) of 0.22 °C, 0.37 °C, and 0.75 °C, respectively, in accordance with the NIM scale. These HTFP blackbodies are being adopted for the study and calibration of radiation thermometers at the NIM.     

1000V多盘感应分压器标准建立

中国计量科学研究院研制了一台1000V多盘感应分压器标准装置,用作工频1000V电压比例标准。该装置使用了一种基于互感器注入的误差补偿技术,可准确提供从1×10^-8到1的宽范围比例出。感应分压器的误差校验使用了包含三同轴屏蔽技术的改进型参考电势增量法,并设计了多比例参考互感器以便对感应分压器进行整体校验。所研制的感应分压器准确度优于1×10^-7,校准结果不确定度小于2×10^-8。     

Research on Time Keeping at NIM

UTC(NIM), which is developed and maintained by NIM, is the time and frequency primary standard in China. UTC(NIM) is generated originally by a clock ensemble, and is traced to UTC by participating in TAI cooperation with GNSS time and frequency transfer methods. TWSTFT earth station has been established at NIM new campus to join the Europe?CAsia link. In this paper, the new development on the realization of UTC(NIM), the GNSS time and frequency transfer and TWSTFT and our briefly future plan are introduced.