On monitoring the process mean of autocorrelated observations with measurement errors using the w-of-w runs-rules scheme

Runs-rules have been widely used since the 1950s in industrial and nonindustrial process monitoring applications to improve the performance of basic and other traditional monitoring schemes. However, none of the studies on runs-rules have accounted for a process with a combined effect of measurement errors and autocorrelation. Hence, in this paper, the use of the w-of-w runs-rules to improve the performance of the Shewhart $\overline{X}$ scheme using an additive model with a constant variance and a first-order autoregressive model is proposed. To reduce the combined negative effect of measurement errors and autocorrelation, we implement a sampling strategy based on rational subgroups in which (a) multiple measurements per item are taken (instead of a standard single measurement) and (b) non-neighboring observations are gathered. Moreover, the latter sampling strategy is incorporated into the values of probability elements of a Markov chain matrix which is used to derive some closed-form expressions for the zero- and steady-state run-length distribution. The main finding of this study is that, with respect to some overall performance measures, the proposed scheme outperforms the existing Shewhart $\overline{X}$ scheme by a significant margin. A real-life example is used to illustrate the practical implementation of the proposed scheme.     

A review on spindle thermal error compensation in machine tools

Thermal error caused by the thermal deformation is one of the most significant factors influencing the accuracy of the machine tool. Among all the heat sources which lead to the thermal distortions, the spindle is the main one. This paper presents an overview of the research about the compensation of the spindle thermal error. Thermal error compensation is considered as a more convenient, effective and cost-efficient way to reduce the thermal error compared with other thermal error control and reduction methods. Based on the analytical calculation, numerical analysis and experimental tests of the spindle thermal error, the thermal error models are established and then applied for implementing the thermal error compensation. Different kinds of methods adopted in testing, modeling and compensating are listed and discussed. In addition, because the thermal key points are vital to the temperature testing, thermal error modeling, and even influence the effectiveness of compensation, various approaches of selecting thermal key points are introduced as well. This paper aims to give a basic introduction of the whole process of the spindle thermal error compensation and presents a summary of methods applied on different topics of it.     

Invited review: Reproducible research from noisy data: Revisiting key statistical principles for the animal sciences

Reproducible results define the very core of scientific integrity in modern research. Yet, legitimate concerns have been raised about the reproducibility of research findings, with important implications for the advancement of science and for public support. With statistical practice increasingly becoming an essential component of research efforts across the sciences, this review article highlights the compelling role of statistics in ensuring that research findings in the animal sciences are reproducible—in other words, able to withstand close interrogation and independent validation. Statistics set a formal framework and a practical toolbox that, when properly implemented, can recover signal from noisy data. Yet, misconceptions and misuse of statistics are recognized as top contributing factors to the reproducibility crisis. In this article, we revisit foundational statistical concepts relevant to reproducible research in the context of the animal sciences, raise awareness on common statistical misuse undermining it, and outline recommendations for statistical practice. Specifically, we emphasize a keen understanding of the data generation process throughout the research endeavor, from thoughtful experimental design and randomization, through rigorous data analysis and inference, to careful wording in communicating research results to peer scientists and society in general. We provide a detailed discussion of core concepts in experimental design, including data architecture, experimental replication, and subsampling, and elaborate on practical implications for proper elicitation of the scope of reach of research findings. For data analysis, we emphasize proper implementation of mixed models, in terms of both distributional assumptions and specification of fixed and random effects to explicitly recognize multilevel data architecture. This is critical to ensure that experimental error for treatments of interest is properly recognized and inference is correctly calibrated. Inferential misinterpretations associated with use of P-values, both significant and not, are clarified, and problems associated with error inflation due to multiple comparisons and selective reporting are illustrated. Overall, we advocate for a responsible practice of statistics in the animal sciences, with an emphasis on continuing quantitative education and interdisciplinary collaboration between animal scientists and statisticians to maximize reproducibility of research findings.     

修形斜齿轮啮合特性计算机仿真研究

齿面修形是提高齿轮副啮合性能的重要手段。主要研究修形的小斜齿圆柱齿轮与渐开线圆柱齿轮的啮合特性。通过计算机仿真了在装配误差存在条件下传动误差和啮合印痕在齿面的分布状况。分析表明在仅存在轴夹角误差的情况下,啮合印痕在两齿面上沿齿向分布在靠近中线的位置,传动误差为不连续的分段直线。     

齿轮加工误差分析及解决方法

分析采煤机齿轮在加工制造中产生的误差原因,着重对加工工艺和工装产生的误差进行分析,采取行之有效的方法对工艺和工装结构进行改进,从而减小加工产生的误差,提高齿轮加工精度。     

加工齿轮产生的误差分析及其解决方法

分析采煤机齿轮在加工制造中产生的误差原因,着重对加工工艺和工装产生的误差进行分析,采取行之有效的方法对工艺和工装结构进行改进,从而减小加工产生的误差,提高齿轮加工精度。     

基于人为错误可靠度的深基坑工程灾害防治

在对深基坑工程中人为错误对工程失效的严重影响进行归纳分析的基础上,提出了在深基坑工程可靠度计算问题中人为错误计算的两种方法,并以润扬大桥南汊北锚碇的设计施工为例探讨了在深基坑工程中人为错误的控制方法,以有效防治工程灾害.     

测量不确定度在水泥胶砂强度检测中的应用

本文结合检测人员在测量不确定度评定中所遇到的实际问题，找出影响测量结果的所有不确定度来源。对其测量方法进行全面的了解，总结经验，加于探讨.     

捷联惯性测量解算方法及测高误差估算

应用四元素法的捷联算法,采用Matlab编程.积分运算采用经典4阶Runge-Kutta算法实现.捷联惯性测量中数学平台和定位解算包括参数初始化、计算装置从惯性器件实时读取数据、载体所在位置重力加速度值计算、速度和位置积分运算等.对可预测的直线轨迹、曲线轨迹对其算法和所编写程序的正确性进行了验证.同时结合一载体运动轨道参数,对各因素对测高误差的影响进行估计,结果证明该方法可行.     

环境温度对CVT计量误差的影响

电容式电压互感器(CVT)的计量精度易受到多种环境因素的影响,其中环境温度为主要的影响因素。温度变化会引起CVT电容分压单元的电容量与介质损耗因数发生改变,从而影响CVT的计量精度。采用仿真与试验相结合的方式研究了温度对220 kV CVT计量误差特性的影响规律。仿真和试验结果表明随着环境温度升高,CVT电容分压单元高、低压臂电容的电容量呈减小趋势,介质损耗因数呈先减小后增大的变化趋势。环境温度的升高会导致CVT的比差负向增大,角差正向增大。在温差大的地区,若CVT存在较大的初始误差,环境温度的变化将导致CVT存在超差的风险。