光干涉绝对重力仪衍射修正

针对绝对重力仪的衍射修正进行研究计算。在光干涉绝对重力仪测量原理基础上,分析并得到激光的高斯特性给重力加速度测量带来的影响。利用90/10刀口法测算激光特性参数(束腰半径),推算得到光衍射(激光的高斯特性)引入的重力加速度值相对修正量。结果表明:激光束腰半径为1.158 6 mm,使用该高斯激光束给重力加速度值引入的偏差,其相对修正量为7.56×10^-9。该方法适用于光干涉绝对重力衍射修正量的计算。     

绝对重力仪国际比对新动态

全球绝对重力仪国际比对活动从1981年起每隔4年在法国国际计量局举办。近两年来,该比对活动发生了一些变化,同时,区域性绝对重力仪国际比对活动日益兴起。中国计量科学研究院代表我国参与了这方面的工作,并介绍了中国计量科学研究自主研制的NIM-II型绝对重力仪参加2009年第8届全球绝对重力仪国际比对的情况和结果     

CCM.G-K2国际比对和NIM-3A型绝对重力仪

基于激光干涉法的自由落体原理,中国计量科学研究院研制了最新的NIM-3A型绝对重力仪。该仪器参加了第9届全球绝对重力仪国际比对CCM.G-K2,根据公布的国际比对结果,NIM-3A型绝对重力仪的测量结果与参比各仪器的测量结果达到了等效一致,测量结果的合成标准不确定度为5.3 μGal。     

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。     

绝对重力仪中落体光心与质心间距的精确测量

为了减少用光学干涉法测量绝对重力过程中落体旋转对测量结果的影响,设计了基于扭摆法调校落体光心与质心间距的方法。采用标准模态分析落体的本征频率,推导光心与质心沿铅锤线方向偏移的测量方程。并分析了角锥棱镜折射率与气体阻尼分别对测量结果的影响。结果表明:入射角在0~0.1°之间,品质因子Q=1000时,调校落体使光心与质心重合,旋转导致的重力加速度干扰最佳可控制在1.4μGal。     

绝对重力仪落体光心与质心空间距离测量

为了准确测量重力仪落体光心与质心距离,减少落体光心与质心不重合引起的旋转对重力加速度测量的影响,设计了落体光心与质心空间距离测量装置。提出了1种光心与质心间距的计算方法,并仿真验证了计算方法的可行性。使用设计的测量装置对落体进行测试,结果表明:激光干涉仪在信号频率为0.3~0.5Hz时的测量精度为0.1nm,提出的计算方法可以使测量系统的A类不确定度优于10μm,最大调校测量误差为1μm。     

Global reconstruction from nonstationary data

One-dimensional time series of a dynamical system with slowly varying parameters are investigated. For estimation of the characteristics of the attractors of such a system which exist for fixed values of the parameters, it is proposed to “cut out” from the time series short segments that belong to the individual attractors and to use them to reconstruct a model dynamical system. Pis’ma Zh. Tekh. Fiz. 25, 74–81 (May 26, 1999)     

Absolute Emission Spectra from Bacillus subtilis and Escherichia coli Vegetative Cells in Solution

Spectrally resolved emission (270-560 nm) from dilute suspensions of washed Bacillus subtilis and Escherichia coli were measured by use of tunable laser excitation between 270 and 300 nm. Integrated absolute emission cross sections increase with decreasing excitation wavelength and range from 1.8 x 10(-12) to 6.0 x 10(-11) cm(2)/(particle sr). An emission band near 340 nm dominates all observed spectra. At each excitation wavelength spectrally resolved emissions from the E. coli and B. subtilis suspensions are indistinguishable.     

全球水产生物安保战略及其国外经验的启示

本文介绍了全球水产生物安保战略的国际组织框架,阐述了联合国粮食及农业组织(FAO)、世界动物卫生组织(OIE)和国际水产兽医生物安保联盟对全球生物安保战略所提出的建议,举例说明了美国、泰国、印度尼西亚对虾种业生物安保的实践经验,为我国水产养殖业的健康可持续发展提供了借鉴。     

Absolute dynamic viscosity measurements of subcooled liquid oxygen from 0.15 MPa to 1.0 MPa

New absolute dynamic viscosity measurements of subcooled liquid oxygen are presented which were acquired in the pressure and temperature domains from 0.15 MPa to 1.0 MPa and from 55.20 K to 90.19 K, respectively. The measurements were acquired with an uncertainty of 1% at a 95% confidence level using a pressurized gravitational capillary (PGC) viscometer specifically designed for subcooled liquefied gases. The measurements are summarized by Arrhenius–Eyring plot parameters (μ = Ae^E/RT), and interpreted with respect to the chemical reaction rate theory of viscosity by Eyring. The Arrhenius–Eyring plot parameters reproduce the dynamic viscosity measurements with only a 2% RMS error, which is remarkable considering just two parameters are involved, A, the factor which includes the weak pressure dependence of the dynamic viscosity, and E/R, the barrier energy of the flow, where R is the universal gas constant. Although the Arrhenius–Eyring plot parameters do not have a discernible pressure dependence in the present work, the pressure coefficient versus temperature for the dynamic viscosity was determined from line plots of the dynamic viscosity versus pressure. The pressure coefficients suggest that the pressure dependence is very weak, yet positive, and increases with decreasing temperature. Measurements at pressures an order-of-magnitude higher are required to confirm this suggestion.     

The NIST High Accuracy Scale for Absolute Spectral Response from 406 nm to 920 nm

We describe how the National Institute of Standards and Technology obtains a scale of absolute spectral response from 406 nm to 920 nm. This scale of absolute spectral response is based solely on detector measurements traceable to the NIST High Accuracy Cryogenic Radiometer (HACR). Silicon photodiode light-trapping detectors are used to transfer optical power measurements from the HACR to a monochromator-based facility where routine measurements are performed. The transfer also involves modeling the quantum efficiency (QE) of the silicon photodiode light-trapping detectors. We describe our planned quality system for these measurements that follows ANSI/NCSL Z540-1-1994. A summary of current NIST capabilities based on these measurements is also given.     

如何防止受控文件失控

按照ISO/IEC 17025<检测和校准实验室能力认可准则>要求实验室应建立和保持程序来控制构成其管理体系的所有文件(内部制订或来自外部的),诸如法规、标准、其他规范化文件、检测和/或校准方法,以及图纸、软件、规范指导书和手册;而且应建立识别管理体系中文件当前的修订状态和分发的控制清单或等效的文件控制程序并使之获得,以防止使用无效和/或作废的文件;可见文件在控制中包含了大量的内容,它们是质量管理体系的核心,也是整个实验室认可过程中重点评审的要素,所以其管理状态将直接影响实验室认可的结论.……     

Failure analysis for coming out of shaft from shrink-fitted ceramic sleeve

This paper deals with failure analysis for coming out of the steel shaft from ceramic sleeve connected by shrink fitting. Only low shrink fitting ratio can be applied because of the brittleness of the ceramic sleeve. However, the steel shafts may be loosening out from the ceramic sleeve under such low shrink fitting ratio. In this study, the coming out behavior of the shaft during rotation is analyzed by the finite element method. The roller rotation is replaced by shifted load in the circumferential direction on the fixed roller. It is found that the load rotation can be approximated by the discrete load shifting at the interval angle θ₀ = 12° within 1% error. The effect of the shrink fitting ratio on the coming out of the shaft is discussed as well as several other parameters, such as Young's modulus of the shaft, the friction coefficient, magnitude of the load, and geometry of the shaft. Furthermore, it is found that the shear stress distribution at the shrink-fitted area may be useful for evaluating whether the coming out occurs or not.     

Global ultraviolet spectra derived directly from observations with multichannel radiometers

Some general features of multichannel filter radiometers operating in the UV region of the solar spectrum are reviewed with emphasis on calibration problems that are due to incomplete knowledge of responsivity in the UV-B region. An alternative calibration procedure that is able to generate a full UV spectrum obtained by a constrained inversion method is presented. Accuracy of such spectra is assessed with simulated and with real data. A comparison between customary calibration and an alternative procedure is made in terms of monochromatic UV-B irradiance and CIE dose rate (CIE is the Commission Internationale de l'Eclairage) and indicates that irradiances are estimated within 8% accuracy with solar zenith angles as great as 60 degrees and that dose rates are within 6% for any solar zenith angle. The advantage of having an additional channel in the UV-B region is considered.     

Absolute measurement of the generated aberrations from liquid crystal spatial light modulator using a common-path interferometry

A compact common-path interferometry is proposed to measure the wavefront aberration generated from liquid crystal spatial light modulator (LC-SLM). The LC-SLM is encoded with an aberration pattern and illuminated with a linearly polarized light oriented at ±45° with respect to the fast axis of liquid crystal, which is vertically oriented. The horizontal polarization component of the incident beam is not affected by the driving signal, while the vertical polarization component is modulated to the aberration loaded to the LC-SLM. By imposing a quarter-wave plate and a rotating analyzer, these two waves create four frames of phase-stepped interferograms. The aberration to be measured can be retrieved, and the result does not include any systematic error such as the substrate error of LC-SLM. Therefore, this method can implement absolute measurement, and help us to evaluate perfectly the fitting accuracy of the LC-SLM.     

Global trend in aquatic ecosystem research from 1992 to 2011

Aquatic ecosystems are ecologically important, but continuously threatened by a growing number of human induced changes. This study evaluates the research trends of “aquatic ecosystem” between 1992 and 2011 in journals of all subject categories of the science citation index and social sciences citation index. The analyzed parameters include publication output, cited publication, document type, language, distributions of journal, author, country and institutes, and analysis of author keywords and keywords plus. The results showed that over the past two decades, there was a consistent growth in publication output with involvement of increasing number of countries and institutions, and North America was still the leading region in the subject. Classification of the top 30 author keywords indicated that more research attentions were paid to the study on aquatic organism, water environment and aquatic ecosystem condition. Aquatic ecosystem, water quality, and fish were the top three most frequently used author keywords. In addition, owing to its significant impact on aquatic ecosystems, climate change has been placed crucial emphasis recently. Aquatic ecosystem research trend was shifting from water environment to aquatic ecosystem wide issues.     

The settling out of ionizing additives from a stream of combustion products

We examine the settling out of the additives K₂CO₃ and K₂SO₄ from a stream of combustion products onto a laterally streamlined tube. Experimental data are given and the unique features of the process are discussed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 16, No. 6, pp. 1062–1067, June, 1969.