科里奥利质量流量计在CNG加气机计量中的应用

介绍了科里奥利质量流量计在压缩天然气（CNG）加气机计量中的构成和工作原理,分析了应用中出现的零漂、重复性差等问题,提出了相应的解决方案,重点探索了质量流量计安装直管段对计量重复性的影响。     

稻谷脂肪自动酸滴定仪设计与实现

传统的人工测定稻谷脂肪酸系统由于使用肉眼观察滴定终点,因此,具有误差较大、测定结果不准确、重复性差等缺点.稻谷脂肪酸自动滴定仪使用光学传感器以滴定过程的颜色变化为控制依据确定滴定终点,结果准确稳定,一致性好.通过对大量的测试数据的分析,提出了采用差分滤波法处理颜色数据确定滴定终点的实现方案,证明了该方案的可行性和实用性,并设计实现了系统样机.通过在样机上做的大量实验结果表明,本设计测定结果的重复性和精度达到了国标GB /T15684-1995的要求.     

利用点弦距离递归的图像角点检测算法

目的 传统的基于边缘轮廓的角点检测算法需要计算每一个边缘像素点的曲率,对噪声和局部变化敏感,极易造成检测结果的不稳定。针对这一问题,提出一种利用点弦距离递归的角点检测算法。方法 首先,利用Canny边缘检测器提取边缘轮廓线。其次,用3个不同尺度的高斯核对边缘线进行平滑,对每一个高斯尺度平滑后的边缘线,连接首尾端点形成一条弦,计算边缘轮廓上每个边缘像素点到弦的距离,将点弦距离最长的像素点标为候选角点,该像素点将原边缘轮廓线分成两条边缘,然后将该像素点与首尾端点连接成两条弦,重新计算点弦距离,将所有距离大于设定阈值的点作为候选角点。最后,利用多尺度技术对候选角点进行判决并得到最终角点。结果 与现有的基于曲率计算的角点检测算法相比,本文算法不需要计算一、二阶导数,有效避免了局部变化带来的计算误差。通过计算得到4个角点检测器的平均排名依次为Harris （4.0）、He&Yung （2.67）、CPDA （1.83）、本文算法 （1.5）。与其他3种经典的角点检测算法相比,本文提出的检测算法排名第一,因此表现出了更好的检测性能。结论 提出了一种新的利用点弦距离递归的角点检测算法。从实验结果看,本文提出的角点检测器在图像仿射变换、JPEG质量压缩和高斯噪声条件下有更好的平均重复性和定位误差。     

高精度光电自准直测角系统的设计和验证

为了提高自准直测角系统的测量精度,本方案设计了4个关键技术,并通过测量重复性试验和示值比对试验表明该高精度光电自准直测角系统已达到JJG 202-2007《自准直仪检定规程》规定的1级技术要求。     

追尾碰撞中颈部挥鞭伤害试验的重复性

采用ORM(Objective rating method)方法,对搭载有BioRID假人的后碰台车试验进行了重复性研究,分别对台车试验的打出波形、BioRID假人伤害指标、信号峰值、峰值发生时刻、以及信号脉冲的形状进行了重复性分析。结果表明,采用BioRID假人进行后碰台车试验具有很高的重复性。     

The influence of contact geometry on friction and wear characteristics

This paper describes some results of evaluating the influence of contact geometry on tribological characteristics. Friction characteristics obtained for a distributed contact (pin‐on‐disc and block‐on‐ring), a linear concentrated contact (pin and vee‐block and block‐on‐ring) and a point concentrated contact (ball‐on‐disc and three cylinder‐cone) are presented. The wear scars were analysed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show different values of friction and wear coefficients for the different types of contact geometry. The paper also assesses the effect of non‐test characteristics, e. g., vibration.     

时移地震非一致性影响研究与互均衡效果验证

用地震子波对时移地震非一致性造成影响进行了模拟。将影响因素概括为4种形式，即时移、相位变化、振幅量级不一致，频宽不一致。采用互均衡技术对以上4种情况进行校正，达到了理想的效果。为实际资料的处理和方法研究奠定了理论基础。     

检具随机误差的验收评定方法

介绍了四种常用的检具随机误差验收评定方法,并分析了各种评定方法的特点及适用性。     

Estimation of genetic parameters and single-step genome-wide association studies for milk urea nitrogen in Holstein cattle

The main objectives of this study were to estimate genetic parameters for milk urea nitrogen (MUN) in Holstein cattle and to conduct a single-step (ss)GWAS to identify candidate genes associated with MUN. Phenotypic measurements from 24,435 Holstein cows were collected from March 2013 to July 2019 in 9 dairy farms located in the Beijing area, China. A total of 2,029 cows were genotyped using the Illumina 150K Bovine Bead Chip, containing 121,188 SNP. A single-trait repeatability model was used to evaluate the genetic background of MUN. We found that MUN is a trait with low heritability (0.06 ± 0.004) and repeatability (0.12). Considering similar milk production levels, a lower MUN concentration indicates higher nitrogen digestibility. The genetic correlations between MUN and milk yield, net energy concentration, fat percentage, protein percentage, and lactose percentage were positive and ranged from 0.02 to 0.26. The genetic correlation between MUN and somatic cell score (SCS) was negative (?0.18), indicating that animals with higher MUN levels tend to have lower SCS. Both ssGWAS and pathway enrichment analyses were used to explore the genetic mechanisms underlying MUN. A total of 18 SNP (located on BTA11, BTA12, BTA14, BTA17, and BTA18) were found to be significantly associated with MUN. The genes CFAP77, CAMSAP1, CACNA1B, ADGRB1, FARP1, and INTU are considered to be candidate genes for MUN. These candidate genes are associated with important biological processes such as protein and lipid metabolism and binding to specific proteins. This set of candidate genes, metabolic pathways, and their functions provide a better understanding of the genomic architecture and physiological mechanisms underlying MUN in Holstein cattle.     

Evaluating the measurement capability of a wheel profile measurement system by using GR&R

Reliable data with less variation play a key role for acceptance of the usefulness of the measurement output of a wheel profile measurement system (WPMS) in a railway network. However, in practice, most studies are carried out without checking the reliability of data from such a system, which may lead to inappropriate maintenance strategies. To ensure the measurement capability of WPMS and to support robust maintenance in railway systems, this study has evaluated measurement data for the flange height, flange thickness, flange slope, and tread hollowing of rolling stock wheels by using gauge repeatability and reproducibility (GR&R). In this study, acceptance and rejection criteria for the precision-to-tolerance ratio (PTR), signal-to-noise ratio (SNR), and discrimination ratio (DR) have been employed to evaluate the measurement capabilities. For the purpose of illustration, we have implemented a new proposed approach. This approach involves both an analysis using graphs with four regions with a confidence interval (CI) of 95% and an analysis using a graph with three regions with only the predicted values; the latter type of graph represents an innovation made in this study. This graph has the advantages that it can visualize three different levels of data quality in same figure, namely “unacceptable”, “acceptable” and “good”, and also include a number of measures without becoming unclear, which are features that have been missing in previous presentations. The results show that the measurements of the flange slope are on an acceptable level, while those for the flange height, flange thickness and tread hollowing have to be rejected as unacceptable. The action proposed for increasing the quality of data on the flange height, flange thickness and tread hollowing is to enhance the calibration of the WPMS. In conclusion, GR&R is a useful tool to evaluate the measurement capability of WPMS and to provide helpful support for maintenance decision making. This investigation also shows that there is good reason to be careful when selecting measures and when interpreting the results, since, for a certain wheel profile parameter, when one measure is used, the results may be acceptable, but when another measure is used, the results may be unacceptable.