浅析天然气组成分析方法标准对精密度的要求

天然气组成分析是天然气工业中最为基础的分析项目,我国强制性标准GB 17820-2012《天然气》规定的二氧化碳浓度和高位发热量两个指标均与天然气组成分析有关,而分析结果的精密度要求是天然气组成分析方法规定的重要技术参数。比较了国内外天然气常规组成分析方法标准规定的精密度值,并通过试验,验证了不同方法分析结果所能达到的精密度,对各方法标准规定精密度值的合理性进行了探讨,其结论可为使用者选择合适的方法标准分析天然气组成提供借鉴。     

精密度试验数据的计算机处理

应用C、FORTRAN和FoxBASE~+等多种程序设计语言混合编程,设计了符合国家标准GB 6379的测试方法精密度试验数据统计处理的计算机软件和数据库管理系统。软件已应用于硅酸盐岩石化学分析方法等多批标准方法的精密度试验数据处理工作,经该软件处理的标准方法中,已有45种分析方法批准为国家标准。     

Posterior distributions for functions of variance components

This paper uses a Bayesian approach to examine the posterior distributions of linear and non-linear functions of variance components in balanced two-way analysis of variance designs. The paper shows how exact posterior distributions for such functions can be readily described using Monte Carlo simulations where independent draws from the distributions are obtained. It is thus very straightforward to obtain percentiles, means, standard deviations, and other summary measures for the posterior distributions.     

Improving Process Capability of Manufacturing Process by Application of Statistical Techniques

This article describes the application of statistical techniques in solving a problem of high rejection and rework due to variation in the machining process. The rejections in the shop floor of a company were studied through Pareto analysis for prioritizing the problems due to different sources. The grinding process was found to be the most contributing among all the processes towards rejection and rework. The process capability of this grinding process was evaluated and found to be very low. A step by step method was adopted by the application of several statistical techniques such as design of experiments for solving this problem. As a result of the study, the process capability has improved drastically. This has lead to reduction in the problems due to high rejection and rework in shop floor.     

Interactive drawing of the left ventricular borders from cine magnetic resonance images

The calculation of the left ventricular (LV) function requires the endocardial and epicardial contours of the cavity to be accurately defined beforehand. This identification is generally achieved by manual tracing of the LV borders. Such manual methods are tedious and time-consuming, limiting their clinical usefulness for cardiac quantitative analysis. The purpose of this study was to evaluate an efficient method for drawing the LV borders from magnetic resonance (MR) images. This technique, based on the use of cubic B-spline curves to modelize the shape of the cavity, allows an interactive and real-time remodeling of the contours. The variability and the accuracy of this contour tracing tool have been evaluated on standard cine-MR images obtained in 10 healthy volunteers in a short-axis view. Theendocardial and epicardial areas and themean local error between the contours were compared through interobserver and intraobserver analyses. A good correlation was observed between the enclosed areas in both studies (r>0.98 for endocardium,r=0.99 for epicardium). The mean local error between the contours was less than 2.8% for the endocardial borders and less than 1.4% for the epicardial borders. This method has a high degree of flexibility for the interactive trace and deformation of contours. Although further validation is needed, this method may prove useful in clinical application to permit the measurement of LV function from MR imaging.Address for correspondence: Departement de Radiologie, Hôpital Cardiovasculaire et Pneumologique, BP Lyon Montchat, 69394 Lyon Cedex 03, France. Additional reprints of this chapter may be obtained from the Reprints Department, Chapman & Hall, One Penn Plaza, New York, NY 10119.     

混凝土钢筋位置测定仪的量值溯源

为了解决交通运输行业内混凝土钢筋位置测定仪的量值溯源问题,分析了混凝土钢筋位置测定仪的使用和计量现状,确定了计量参数,研制了标准器组和标准装置,并开展重复性实验验证。通过建立的"混凝土钢筋位置测定仪—混凝土钢筋位置测定仪标准器组—混凝土钢筋位置测定仪计量标准装置—国家长度基准"溯源链,能够满足混凝土钢筋位置测定仪检定/校准的需要。     

热连轧钢材力学性能在线预报的研究与应用

 传统的产品力学性能检测是一种建立在统计学随机抽样理论基础上的检验方法,即在实验室中对取样板卷的头尾部切割样品进行检测,检测结果代表整批产品的力学性能。由于钢材生产流程长,生产过程控制参数存在一定的波动,传统力学性能检测方法不能反应每一卷带钢的力学性能,所检测样品的代表性不够充分。随着工业互联网、大数据和人工智能技术的飞速发展,特别是工业大数据相关技术的发展和应用,为这一问题的解决提供了新的途径。以实现山东钢铁集团日照有限公司热连轧产品力学性能在线预报为试验对象,以热连轧产品生产全流程关键控制工艺参数为基础,采用神经元网络、随机森林等算法建立碳素结构钢、低合金高强度结构钢的力学性能预报模型,构建了一种基于工业大数据为基础的热轧产品力学性能预报系统,包括数据采集、数据清洗、模型训练、结果分析、再现性试验和在线应用。力学性能在线预报系统已成功运行2年多时间,系统的预测精度高、稳定可靠。预测结果精度在±6%以内的比例达到90%以上,MAPE(平均绝对百分误差)不大于4%,均低于再现性检测水平,预测结果完全可以取代检测试验;提高了生产效率,缩短了产品的检测周期,轧后即可掌握产品的力学性能,降低了生产成本,已成为生产运行过程不可缺少的环节。     

On the reproducibility of air plasma spray process and control of particle state

Controlling particle state is important to not only achieve the required microstructure and properties in coatings but also to clearly isolate and understand the role of other clusters of variables (such as the various substrate and deposition conditions) on the aforementioned attributes. This is important to design coatings for high performance applications and in the ongoing efforts toward achieving prime reliance. This study examines the variability in particle state and explores a few strategies to control them for improved reproducibility with the aid of in-flight particle and plume sensors. The particle state can be controlled by controlling the torch parameters or by directly controlling the particle state itself via feedback from particle and plume sensors such as DPV 2000 (Tecnar Automation Ltd, Quebec, Canada) and torch diagnostic system-spray plume trajectory sensor (TDS-SPT) (Inflight Ltd, Idaho Falls, ID). There exist at least a few control protocols to control the particle state (predominantly temperature and velocity) with judicious choice of critical parameters. In the present case particle state has been controlled by varying the critical torch parameters (primary gas flow and arc current) in a narrow range using 8% YSZ of angular morphology (fused and crushed) with 10–75 μm size distributions in conjunction with a N₂-H₂ laminar (nonswirl) plasma. Two important results emerge: (a) The particle state resulting from averaged individual particle measurements (DPV 2000) is surprisingly stable with variability in T<1% and variability in V of <4%. Ensemble approaches yield a somewhat higher variability (5% in temperature). Despite this the variability in basic coating attributes such as a thickness and weight is surprisingly large. (b) Applying a much simpler control strategy to only control the particle injection and hence the particle trajectory results in reduced variability in coating attributes. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

Combining Scott-Knott and GR&R methods to identify special causes of variation

Measurement error is an unavoidable source of variation in any decision-making process based on experimental research. Components of variation due to measurement system and manufacturing process must be estimated and special causes of variation should be reduced whenever possible. GR&R (gage repeatability and reproducibility) studies quantify these sources of variation by using analysis of variance. The main contribution of this paper is to conjoin GR&R and the multiple comparisons method of Scott-Knott in order to help practitioners identifying special causes of variation in empirical studies. Stainless steel cladding process has been evaluated to validate the proposed procedure. The experimental findings have shown that the well-structured method based on Scott-Knott test was effective in indicating the source of error due to reproducibility.