Characterization and improvement of absorption and scattering by profiled architectural surfaces without specialized test facilities

A turntable apparatus and measurement procedure, based on ISO 17497-1, were developed for measuring the random-incidence absorption and scattering of surfaces, without specialized facilities. While not highly accurate, they proved adequate for determining the general characteristics of surfaces. Two original profiled wooden architectural surfaces, and a hard, flat reference surface, were characterized, and found to have low absorption and scattering. They were then modified for increased absorption by creating Helmholtz-resonator configurations, obtaining good performance at low- and mid-frequencies. They were also modified for increased scattering, in one case by creating a Schroeder diffuser. In the other case, the surface was integrated into a novel frame-array configuration, which scattered sound very well above 500 Hz.     

X-ray tube spectra measurement and correction using a CdTe detector and an analytic response matrix for photon energies up to 160 keV

The aims of our work were: i) to measure selected normalized X-ray beam spectra with the commercially available cadmium telluride detector based spectrometry system; ii) to construct the approximate response matrix of the detector using a simple algebraic model approach; iii) to reconstruct the physical energy spectra from the measured instrumental spectra using the detector response matrix; iv) to compare the obtained spectra parameters with the published and reference data in order to verify the model and to optimize the measurement setup if necessary. In particular, the spectra of five “narrow-spectrum series” beams, namely N60 to N150, were measured with a spectrometry system consisting of the Amptek XR-100T X-ray semiconductor detector and the PX5 multichannel analyser. Two different measuring geometries were used. The response matrix R(E, E′) of the detector was constructed which quantifies the energy dependence of the relative detection efficiency of the detector, the probabilities of the escape effects, and the probability of the Compton effect. A single matrix operation was applied to recover the physical energy spectra from the measured instrumental ones. The parameters of the corrected spectra were compared with the published and reference data. Despite the fact that the effect of incomplete charge collection was not implemented in the detector model, a fully satisfying quantitative correspondence was observed between the measured corrected spectra and the available reference data.     

基于ISO10110-5的面形评价参数研究

现在国外商用ZYGO干涉仪可提供一些基于ISO10110-5的面形评价参数,而国内的自制干涉仪还没有这项功能.IS010110-5中提出这些面形评价参数的计算可以通过波面分解的方法实现.运用Gram-Schmidt最小二乘法拟合得到Zernike多项式系数,再从包含被测信息的原始波面中依次减去各种表面面形偏差,就可实现对这些参数的定量分析.通过与ZYGO干涉仪的输出对比,验证了自编拟合程序所得数据的有效性,而通过波面分解得到的各种干涉图也有益于光学加工者分析偏差原因和器件应用后果.     

Sample preparation methods for subsequent determination of metals and non-metals in crude oil—A review

In this review sample preparation strategies used for crude oil digestion in last ten years are discussed focusing on further metals and non-metals determination. One of the main challenges of proposed methods has been to overcome the difficulty to bring crude oil samples into solution, which should be compatible with analytical techniques used for element determination. On this aspect, this review summarizes the sample preparation methods for metals and non metals determination in crude oil including those based on wet digestion, combustion, emulsification, extraction, sample dilution with organic solvents, among others. Conventional methods related to wet digestion with concentrated acids or combustion are also covered, with special emphasis to closed systems. Trends in sample digestion, such as microwave-assisted digestion using diluted acids combined with high-efficiency decomposition systems are discussed. On the other hand, strategies based on sample dilution in organic solvents and procedures recommended for speciation analysis are reported as well as the use of direct analysis in view of the recent importance for crude oil field. A compilation concerning sample preparation for crude oil provided by official methods as well as certified reference materials available for accuracy evaluation is also presented and discussed.     

Development and accreditation to ISO/IEC 17025 calibration status of a melting point measurement facility for the UK

A melting point measurement facility for the UK has been developed and accredited to ISO/IEC 17025 Calibration status for the determination of the liquefaction temperature of pure substances from 35 to 250°C. The facility is based upon a commercial instrument, i.e. an oil bath fitted with an aluminium block (Isotech, model 798 EHT), a precision multimeter (Isotech TTI-7), a thermocouple directly inserted in the sample under investigation and a platinum resistance thermometer (PRT) tracking the block temperature. The homogeneity of temperature bath/block was investigated and the PRT used for the traceability of the measurements was calibrated by NPL and traceable to ITS-90. The process was validated using four current LGC Certified Reference Materials (CRMs):

〈2, 1〉-Compact operators

We consider the class of the continuous L _2,1 linear operators in L ₂ that are sums of the operators of multiplication by bounded measurable functions and the operators sending the unit ball of L ₂ into a compact subset of L ₁. We prove that a functional equation with an operator from L _2,1 is equivalent to an integral equation with kernel satisfying the Carleman condition. We also prove that if T ∈ L _2,1 and VTV ^?1 ∈ L _2,1 for all unitary operators V in L ₂ then T = α1 + C, where α is a scalar, 1 is the identity operator in L ₂, and C is a compact operator in L ₂.     

Internal user inquiries as a useful tool for adjustment of the quality system and for quality improvement

Who could be better than the staff themselves to point out inappropriate and ineffective elements in a quality system? A dialogue between the supplier and the customer for clarification of the customers' requirements and possible quality problems is often part of a quality management system. Of no less importance is a dialogue with the staff who "live" with the quality system in the everyday work environment, handling procedures, keeping records, and controlling documents, etc. For this reason a simple internal user inquiry was conducted. The anonymous inquiry form considered areas which effect daily work, and posed questions which, we had reasons to believe, could be tender points among staff. The result was a very positive feedback on the questions, and several advantages and disadvantages were brought forward. Our experience after 2 years with ISO 9001 certification is that internal inquiries are just as important as the dialogue with customers in maintaining an appropriate and effective quality system. Furthermore, such inquiries focus on the quality system and involve the staff in adjustments, tailoring the system and in quality improvements.     

八类缆布线系统标准新进展

针对IEEE的标准勘误,ISO/IEC正着手制定一项ISO/IEC 11801-x布线标准的先导标准,并用来支持25GBASE-T以太网规范。为了促进研发生产厂商的预先研究,介绍了相关标准中技术内容的重要变化,并给出了为了拓展八类缆布线长度而对八类对称电缆及连接器的改进建议。     

轨道交通车辆用电缆RAMS分析

介绍了国际铁路行业IRIS(国际铁路工业标准)认证的基本情况、认证标准的发展过程,以及其中RAMS(可靠性、可用性、可维修性、安全性)部分内容的关键作用。对RAMS内容与电缆行业的匹配性、适用性及具体执行过程进行解读与说明。基于轨道交通车辆用电缆为单一部件的特点以及失效后只能更换的特性,故只适用于可靠性和安全性的要求。同时,确认电缆产品通过试验保证可靠性、通过Arrhenius方法推导90℃热寿命超过30年保证安全性。希望以此为计划进行IRIS认证的电缆企业提供参考。