Issues in single-mode fiber standardization

A review is given of the main organizations responsible for optical fiber standards activities, followed by a general discussion of specifiable characteristics of single-mode fibers and test methods for measuring them. The parameters and methods are then discussed in detail, with areas of disagreement among standards groups pointed out and directions of future work indicated.     

Standardisation of electrostatic test methods and electrostatic discharge prevention measures for the world market

With the development of world markets and large organisations working with sites in many continents, the need has grown for international standards in electrostatic test methods and Electrostatic discharge (ESD) prevention measures. Progress in world standards developed by the International Electrotechnical Commission (IEC) Technical Committee 101 (Electrostatics) has so far been mainly driven by the needs of the electronics industry, but has also laid down basic materials test methods, test methods for specific applications, and requirements for protection of electronic devices from electrostatic damage. Much of the work done in this area has its roots in test methods developed by the ESD Association in the US. More recently, work on test methods for electrostatic ignition hazards avoidance, for example in Intermediate bulk containers (IBCs), has commenced. Meanwhile the European Committee for Electrotechnical Standardization (CENELEC) has been active issuing a code of practice for avoidance of electrostatic hazards, as well as various test methods. Much of this is driven by the need for standards to address compliance with European Directives. This paper examines some areas in which new test methods are needed or are currently being developed by IEC TC101 for the world market.     

Standards for surface flaws

A two channel microscope image comparator is described which is capable of quantifying all current national standard defects. It has been designed to solve the difficulties that arise when optically worked surfaces, which have been visually assessed, are transferred between companies working to different standards and methods of flaw measurement. The instrument, using both visual and objective methods, can give the same severity rating for a surface flaw, thus allowing for transferable standards.     

Accurate measurement of pressure

This paper briefly describes the fundamental principles of the instruments used for accurate measurement of hydrostatic pressure and in particular the use of piston gauges as primary pressure standards. Different methods for the calibration of secondary standards have been discussed and in particular, emphasis has been given to the calibration of secondary piston gauges against the primary standards by the cross-float method along with the evaluation of uncertainties attached to different correction factors associated with the measurement of pressure from these gauges. The importance of secondary pressure standards in the region 0.1 GPa to several GPa has also been defined.     

Realisation and metrological characterisation of thickness standards below 100 nm

High-accuracy film thickness measurements in the range below 100 nm can be made by various complex methods like spectral ellipsometry (SE), scanning force microscopy (SFM), grazing incidence X-ray reflectometry (GIXR), or X-ray fluorescence analysis (XRF). The measurement results achieved with these methods are based on different interactions between the film and the probe. A key question in nanotechnology is how to achieve consistent results on a level of uncertainty below one nanometre with different techniques.Two different types of thickness standards are realised. Metal film standards for X-ray techniques in the thickness range 10 to 50 nm are calibrated by GIXR with monochromatised synchrotron radiation of 8048 eV. The results obtained at four different facilities show excellent agreement. SiO₂ on Si standards for SE and SFM in the thickness range 6 to 1000 nm are calibrated by GIXR with monochromatised synchrotron radiation of 1841 eV and with a metrological SFM. Consistent results within the combined uncertainties are obtained with the two methods. Surfaces and interfaces of both types of standards are additionally investigated by transmission electron microscopy (TEM). PACS 61.10.Kw; 68.55.Jk; 06.20.Fn; 06.60.Mr; 07.79.Lh     

Optimization of two methods based on ultrasound energy as alternative to European standards for soluble salts extraction from building materials

The Italian recommendation NORMAL 13/83, later replaced by the UNI 11087/2003 norm, were used as standard for soluble salts extraction from construction materials. These standards are based on long-time stirring (72 and 2h, respectively) of the sample in deionized water. In this work two ultrasound based methods were optimized in order to reduce the extraction time while efficiency is improved. The instrumental variables involved in the extraction assisted by ultrasound bath and focused ultrasounds were optimized by experimental design. As long as it was possible, the same non-instrumental parameters values as those of standard methods were used in order to compare the results obtained on a mortar sample showing a black crust by the standards and the optimized methods. The optimal extraction time for the ultrasounds bath was found to be of two hours. Although the extraction time was equal to the standard UNI 11087/2003, the obtained extraction recovery was improved up to 119%. The focused ultrasound system achieved also better recoveries (up to 106%) depending on the analyte in 1h treatment time. The repeatabilities of the proposed ultrasound based methods were comparables to those of the standards. Therefore, the selection of one or the other of the ultrasound based methods will depend on topics such as laboratory facilities or number of samples, and not in aspects related with their quality parameters.     

基于人机工程学的光学显微镜机械结构设计

为研究出更合理的光学显微镜机械结构设计原理及相关规范,基于人机工程学的设计理念,参阅我国光学显微镜的相关规范,对金相显微镜的机械结构——载物台、调焦装置、物镜转换器等的设计进行了分析。从安全可靠和舒适经济的角度,提出了适合金相显微镜机械结构的人性化设计方法和原则。该设计原则和机械结构设计尺寸的计算公式具有普遍适用性。     

近红外漫反射光谱法快速无损鉴别阿胶真伪

采用近红外光谱漫反射光谱技术和模式识别技术快速鉴别阿胶真伪.收集来源不同的阿胶(真品8个,伪品6个),采集其近红外漫反射光谱,使用多重散射校正和小波变换对光谱进行预处理后,分别应用相似度匹配和马氏距离方法建立质量鉴别模型.相似度法使用真品谱图作为标准谱图,用样品谱图与标准谱图的相似度值来鉴别阿胶质量;对阿胶样品进行重复扫描得到28张谱图,随机分为3组后应用马氏距离法建立交叉验证鉴别模型.两种模式识别方法均能准确无误的鉴别阿胶真伪,表明近红外光谱和模式识别技术结合可快速、准确、客观地进行阿胶质量鉴别,可推广到其他中成药的质量鉴别.     

The MP2 binding energy of the ethene dimer and its dependence on the auxiliary basis sets: a benchmark study using a newly developed infrastructure for the processing of quantum chemical data

Data intense processes such as the establishment of quantitative structure–property relationships, the design of novel compounds and also the validation of new quantum chemical methods call for a structured approach for the processing of the results. Whereas in quantum chemistry there are established de facto standards for the computational methods, community standards for [exchange-] data formats are still under development. In this article we present a benchmark study of the (auxiliary-) basis set dependence of the binding energies of an array of conformers of the ethene dimer using the RI-MP2-F12 method. The study was performed using a version of the TURBOMOLE program package modified to provide output in an extended CML format to be imported in an eXist database. This infrastructure for the generation, archival, analysis, and exchange of quantum chemical data is briefly introduced in this article.     

实现光辐射度量基准的几种方法

总结实现光辐射度量基准的几种主要方法,包括黑体辐射器法、电替代绝对辐射计法、自校准硅光电二极管法和光电探测器量子效率绝对测量法。并对各种方法的优缺点进行比较。     

尿素检测方法的研究进展及其快速检测产品现状

进入21世纪,随着生活水平的提高,人们对生活质量的要求越来越高,食品或环境中有害物质的检测成为大众关注的重要部分,尿素的检测就是其中之一.本文介绍了目前国内外对某些行业尿素的一些检测方法,包括直接比色法、间接比色法、色谱法、中红外光谱法等,并讨论了快速检测产品在尿素含量测试方面的应用,对未来尿素的快速检测分析手段进行了展望.     

LA-ICP-MS analysis of platinum-group elements and other elements of interest in ancient gold

One of the most promising methods for ancient gold analysis is laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS). It is a quasi-non-destructive multi-elemental analytical method with detection limits in the range of ppm or below, depending on the element. Internal and external standardizations are used. Different types of standards are necessary to measure major (required for the internal standardization), minor and trace elements. High-purity gold standards doped with trace elements as well as ancient gold coins were found suitable for that purpose. The reproducibility and the accuracy of the results obtained are good enough to consider LA-ICP-MS as reliable to determine trace-element concentrations in ancient gold. PACS 81.70; 82.80     

An overview of standards concerning unwanted electrostatic discharges

For users and manufacturers affected by unwanted electrostatic discharges, the publication of standards concerning the control of such discharges is a great improvement and helps to prevent unwanted electrostatic discharges in potentially explosive atmospheres as well as around electrostatically sensitive devices. There are, for instance, handbook-like documents giving recommendations to help set up effective electrostatic suppressing measures and programs. Another group of standards focuses on certain products and processes and is, thus, more specific. A third group deals with test methods and specifications to help manufacturers develop products that are safe. It also helps in comparisons with other products and thus meets the customer's real needs. To assist manufacturers and customers in finding an applicable standard, an annotated list of the most relevant standards and reports on unwanted electrostatic discharges is given. This compilation does not include special electrostatic processes such as electrostatic copying or material separation except for those processes executed in explosive atmosphere.     

一种吸油烟机声品质满意度分级限值评定方法

声品质作为一种描述吸油烟机噪声听觉感知特性的手段已经被行业所接受,团体标准T/CAS 341–2019《吸油烟机噪声声品质测试方法》给出了吸油烟机声品质测试与建模方法,同时通过声品质指数给出了声品质的数值化表达.该标准为各厂商定量描述声品质提供了依据,但目前仍缺乏对产品声品质满意度级别的划分方法,这不利于声品质技术的推...     

Secondary radiations in spacecraft shieldings

Some problems are discussed which relate to the generation of secondary radiation under the effects of heavy charged cosmic ray particles in spacecraft shielding and in biological tissue. Methods for obtaining the total and differential inelastic interaction cross sections are recommended for use in the calculation of heavy charged particle transport in the shielding. The most extensively used methods for calculating heavy charged particle passage through matter are appraised. The results of calculating cosmic ray doses in biological tissue behind shielding, which allow for the secondary particle contribution, are presented. All the calculations have been made using the set of radiation protection standards approved by the Russian State Committee for Standards. The set of standards has been verified experimentally on board satellites of the Cosmos series.     

无标样X射线定量分析最小二乘法方程的稳定解

无标样法是X射线定量分析的重要方法。无标样定量联立方程中经常出现的病态方程使定量结果出现很大的误差。最小二乘法方程组在某些组合情况下也会出现严重的病态方程。本文提出可以获得可靠的稳定解的无标样X射线定量最小二乘法。指出不同样品数及组合条件下获得稳定解的计算方法:直接最小二乘法、算术平均法、稳定性因子判别法。 关键词：     

Entropy-Based Shear Stress Distribution in Open Channel for All Types of Flow Using Experimental Data

Korean river design standards set general design standards for rivers and river-related projects in Korea, which systematize the technologies and methods involved in river-related projects. This includes measurement methods for parts necessary for river design, but does not include information on shear stress. Shear stress is one of the factors necessary for river design and operation. Shear stress is one of the most important hydraulic factors used in the fields of water, especially for artificial channel design. Shear stress is calculated from the frictional force caused by viscosity and fluctuating fluid velocity. Current methods are based on past calculations, but factors such as boundary shear stress or energy gradient are difficult to actually measure or estimate. The point velocity throughout the entire cross-section is needed to calculate the velocity gradient. In other words, the current Korean river design standards use tractive force and critical tractive force instead of shear stress because it is more difficult to calculate the shear stress in the current method. However, it is difficult to calculate the exact value due to the limitations of the formula to obtain the river factor called the tractive force. In addition, tractive force has limitations that use an empirically identified base value for use in practice. This paper focuses on the modeling of shear-stress distribution in open channel turbulent flow using entropy theory. In addition, this study suggests a shear stress distribution formula, which can easily be used in practice after calculating the river-specific factor T. The tractive force and critical tractive force in the Korean river design standards should be modified by the shear stress obtained by the proposed shear stress distribution method. The present study therefore focuses on the modeling of shear stress distribution in an open channel turbulent flow using entropy theory. The shear stress distribution model is tested using a wide range of forty-two experimental runs collected from the literature. Then, an error analysis is performed to further evaluate the accuracy of the proposed model. The results reveal a correlation coefficient of approximately 0.95–0.99, indicating that the proposed method can estimate shear-stress distribution accurately. Based on this, the results of the distribution of shear stress after calculating the river-specific factors show a correlation coefficient of about 0.86 to 0.98, which suggests that the equation can be applied in practice.     

Noise control problems of passenger airplanes (A review)

The consequences of the introduction of new international standards and regulations that impose limitations on the community noise of passenger airplanes and restrict the operation of noisy airplanes are analyzed. The need in developing new methods for reducing the aircraft noise is stated. The main noise sources inherent in passenger airplanes of different types are considered. The ways of increasing the efficiency of noise-suppressing systems used in power plants and the ways of reducing the intensity of airplane noise sources are determined. The methods for reducing the noise both inside and outside an airplane are described.     

电动汽车充电设施现场电磁兼容特性及防护技术研究

随着电动汽车快速发展,电动汽车充电设施的市场规模及需求日益扩大,充电设施的安全可靠性越来越受到重视。可靠的电磁兼容性能是电动汽车充电设施现场安全可靠运行的必备条件,研究充电设施现场电磁兼容特性及防护技术,做好充电设施现场电磁兼容防护,保证充电设施的安全可靠性,对推动电动汽车发展具有重要意义。根据电动汽车充电设施现行电磁兼容标准,研究充电设施现场电磁兼容测试方法,选择典型充电站进行现场测试,分析充电设施现场电磁干扰特性,并提出电磁干扰抑制与防护措施。充电机产生的谐波干扰是现场主要的电磁兼容问题,采用集中治理与分散治理相结合的方式或者选用具备APFC功能的充电机,能有效解决现场谐波干扰问题。在充电设施开发建设过程中,充分重视充电设施的电磁干扰抑制与防护,提高充电设施电磁兼容性能,是充电设施安全运行的根本保证。     

图像编码技术发展综述

本文回顾了图像编码技术的起源，简要论述了三大经典图像编码技术（预测编码、变换编码和统计编码）和“第二代”图像编码技术的理论指导思想与实现方法，评价了三种图像编码国际标准的技术特点，并分析了两种典型的实时图像编码处理系统的构成