Issues in the characterization of power quality instruments

This paper analyzes some issues related to the metrological characterization of instruments for power quality monitoring, in order to move a step toward the definition of a full performance verification protocol. This protocol should include not only the test situations reported in corresponding standards, but also an array of different voltage and current fluctuations – linked to common power quality issues – that may be encountered in actual power systems. This performance analysis is particularly interesting because it can be found that different power quality instruments, fully meeting characteristics prescribed in standard, still may significantly disagree in some actual measurements. This is due for the existence of unresolved technical and theoretical issues related to the metrological characterization through the classical approaches of these instruments. The aim of the discussion carried out in this paper is also the specification of requirements of a test system devoted to calibration and verification of a power quality monitor, such as it is done in type testing. After a preliminary discussion about technical and theoretical issues related to the performance analysis of these instruments, a proposal of test protocol definition, with reference to some power quality phenomena and based on the design of experiment, is presented.     

Flexible tools for specifying design variation

This paper describes flexible tools for specifying design variations that are based on non-uniform profile tolerance definitions. These tools specify bounds of design performance that can be used for negotiation among engineers in a collaborative design process. These specification methods allow for the capture of many different design functions that are not easily described with current tool designs. In addition, these specification methods lend themselves to efficient verification methods. Profile tolerance definitions provide the most general variation controls for complex mechanical surfaces. Common design practices and engineering standards for profile tolerances exhibit many weaknesses and limitations. We present a rationale for a complete specification approach using B-splines [1, 2] for profile tolerances, and illustrate the approach with examples. B-splines can be used to specify both uniform and non-uniform profile tolerance boundaries. Subsequently, algorithms for the evaluation of actual feature deviations and reporting methodologies for such tolerance zones are presented.     

An unambiguous expression method of the surface texture

The current specification and verification of surface texture in international standards are considered to be too theoretical, complex and over-elaborate for industry. A functional approach that completely expresses the complicated surface texture knowledge for designers and engineers is often nonexistent on the shop floor. Based on Geometrical Product Specification (GPS) philosophy, this paper proposes an unambiguous expression schema of surface texture. The surface texture knowledge in design, manufacture and measurement is based on the general GPS matrix and structured by a categorical object model. Explicit specification and verification processes and the mapping between them are presented. The ultimate goal is to improve the collaboration and bridge the knowledge gap between design, manufacture and measurement of surface texture to reduce product development lead time and improve product quality and performance.     

Improving the development of event-driven control systems in the batch processing industry. A case study

This paper presents the results of an academia-industry collaborative project whose main objective was to test novel techniques for the development of event-driven control systems in the batch processing (e.g., pharmaceutical, fine chemicals, food) industries. Proposed techniques build upon industrial standards and focus on (i) formal synthesis of phase control logic and its automatic translation into procedural code, and (ii) verification of the complete discrete-event control system via dynamic simulation. In order to test the techniques in an engineering environment, a complete discrete-event control system was produced for a benchmark batch process plant based on a standard development method employed by one of the industrial partners. The control system includes functional process specification, control architecture, distributed control system (DCS) proprietary programming code for procedural control at equipment, unit, and process cell levels, and human-machine interfaces: A technical assessment of the development method and the obtained control system was then carried out. Improvements were suggested using the proposed techniques in the specification, code generation and, verification steps. The project assessed the impact of these techniques from both an engineering and economic point of view. Results suggest that the introduction of computer aided engineering (CAE) practices based on the benchmarked techniques and a structured approach could effect a 75% reduction of errors produced in the development process. This translates into estimated overall savings of 7% for green-field projects. Figures were compared with other partners' experience. It is expected that the work load on a given project will shift, increasing the load on process engineers during the specification stage and decreasing the load on the software engineers during the code writing.     

RETRACTED ARTICLE: Study on the expression specifications of geometrical products for function, design, manufacture and verification based on the improved GPS language

For the design, manufacture and verification, a consistent geometrical model for the product functional geometry is required. In this paper, we analyze the relation of the geometrical model with the design, manufacture, and verification of the geometrical product. Based on the improved GPS language, the new concepts and mathematical tools for the geometrical specifications are defined. A surface model defined in the new GPS can be divided into three models: nominal, specification and verification surface model. Expanded geometrical features exist in three “worlds”: nominal, specification and verification worlds. Operations are specific mathematical tools to obtain ideal or non-ideal features, or values of characteristics, their nominal value and their limit(s). The operations used to define the specifications can be divided into seven classes: partition, extraction, filtration, association, collection, construction, and evaluation. With a simple mechanism as an example, the geometrical expression specifications for the functions, design, manufacture and verification of a product are illustrated.     

现代产品几何技术规范(GPS)中基于对偶性的操作技术及其应用

揭示现代产品几何技术规范（geometrical product specification and verification，GPS）中规范过程和检验／认证过程的物象对应关系，以及其表面模型存在着对偶性、操作技术存在着共性的内在规律性；井以几何误差的检验／认证过程为例，阐述利用操作及算子技术实现GPS计量过程数字化的可能性及应用规律；进一步明确基于对偶性的表面模型、操作及操作算子技术，对于实现GPS设计与计量的统一性、与CAX的集成性和数字化功能是至关重要的。     

Uncertainty analysis of roughness standard calibration using stylus instruments

A stylus instrument was characterized and calibrated, including a dynamic calibration of the probe. This stylus instrument was used to calibrate ten roughness standards for six surface roughness parameters. The sensitivity of each parameter of each standard to such measurement conditions as stylus geometry, measurement force, cut-off wavelength, and so forth was determined experimentally. These results were used for an uncertainty evaluation of each parameter for each roughness standard. It is shown that the manufacturers’ specification for the stylus instrument (2% uncertainty in roughness parameters) is approximately correct for the most commonly used samples and parameters, but the uncertainty may range from 0.03% (for sinusoidal profiles) to 100% (for very fine surfaces), depending upon the standard and parameter to be calibrated.     

Crirical physical conditions in the lubrication of automotive valve train systems

Pivoted follower valve train systems are now widely used in modern high-speed automotive engines, and because of their proneness to wear they feature prominently in lubricant specification test requirements. Critical conditions for wear in these systems have been identified by the application of a new model for steady, non-catastrophic,wear processes to the kinematic analysis of the cam/follower contact cycle. It is shown that using this technique, the positions of maximum wear and the reasons for the observed wear severity of pivoted follower systems can be more accurately identified than previously.     

Accuracy assessment of vehicles surface area measurement by means of statistical methods

This paper presents an assessment of the different methods and techniques for measuring a vehicle’s surface area, including a close-range photogrammetric system with calibrated digital cameras, a mid-range laser scanning system and an expeditious method based on a specific tape measurement. These methods are compared with respect to their task-specific accuracy related to the area measurement by means of statistical test for the detection of the significant results. An uncertainty evaluation of these techniques is performed using a standard device that was previously calibrated with a coordinate measuring machine. The assessment of the gathered data reveals a potential for reducing the time and cost associated with close-range photogrammetry for vehicle surface area measurement and digitisation.     

衡器载荷测量仪检定固定式电子秤

鉴于目前大型固定式电子秤现场检测存在砝码运输困难、成本高和效率低等问题。福建省计量科学研究院经过多年的积累,在国家重大科学仪器设备开发专项的资助下,研发出一种能够满足不大于3000个检定分度数的固定式电子秤的新检定装置——衡器载荷测量仪。本文详细介绍了该装置的组成、原理、技术指标,以及应用该测量仪检定固定式电子秤时,测量仪所需的安装基础要求、量值溯源和检定过程等。     

Nonrigid parts’ specification and inspection methods: notions, challenges, and recent advancements

In a free state, nonrigid parts can take on different shapes compared to their design model. Such behavior of nonrigid parts introduces particular challenges to engineers during the geometric and dimensional requirements specification and inspection steps. Given that the choice of inspection method is guided by the requirement specification type, this paper presents two sections dealing, respectively, with the specification and the inspection method used for nonrigid parts. Accordingly, this paper proposes a categorization of the particular specification methods used for the geometric dimensioning and tolerancing of nonrigid parts under the American Society of Mechanical Engineers and International Organization for Standardization standards, as well as a review of the available approaches for the fixtureless inspection method of these parts. Typical applications of each specification method, as well as the advantages and drawbacks of their use, are proposed as general guidance. Finally, the current research trends into the fixtureless inspection methods of nonrigid parts are underscored.     

Decision rules for workpieces based on total uncertainty

The decision rules based on measurement uncertainty are given in ISO 14253-1, according to which only measurement uncertainty is considered in the three-dimensional measurement process, and the workpieces are simply accepted or rejected by measurement uncertainty. It can be seen that the decision rules don’t accord with the basic requirements of the improved GPS system because correlation uncertainty and specification uncertainty are not taken into account, which are existent actually in a GPS process. In order to solve this problem, this paper presents the decision rules based on total uncertainty, according to which the workpieces should be accepted or rejected by total uncertainty. The biggest difference between the two decision rules is whether correlation uncertainty and specification uncertainty have been taken into account. For a given GPS specification, the key of the decision rules based on total uncertainty is to calculate the compliance uncertainty of the corresponding GPS standard-chain. According to ISO 17450-2, a GPS process should be either in the default state or in the special state. Aiming at the two states, the calculation method for compliance uncertainty of a GPS standard-chain is given respectively. It enables us to generate compliance uncertainty on the verification of a GPS specification, which means the acceptance or refusal of a GPS characteristic can be conducted in a quantitative way. The example of flatness least-square assessment indicates that the veracity of assessment could be improved .     

双重公差原则同轴度误差评定的不确定度研究

为了全面地分析影响产品合格性的可能因素,使零件在满足可装配性的情况下降低加工成本,基于双重公差原则同轴度误差评定方法,对零件的依从不确定度进行了研究。根据规范不确定度的定义,充分考虑其组成因素中的提取、拟合和滤波规范,通过极差法求得相应的规范不确定度分量,并合成规范不确定度;采用正交设计的方法,根据优化后的测量方法评定方法不确定度;借助不确定度的黑箱模型,计算执行不确定度分量;最后将上述三种不确定度合成依从不确定度,并进行了实例验证。实验结果表明,该方法可以更全面地分析影响产品合格性的可能因素,从而提高产品检验的合格率,降低其加工成本。     

车车通信链路的功能安全性验证及性能测试

短程无线通信技术快速发展,为基于通信的列车控制系统中的列车到列车(Train to train,T2T)通信链路提供了可行性.引入T2T链路将缩短追踪间隔、提高运营效率.形式化方法是一种系统设计技术,使用有严格数学定义的模型来确保所有行为按预期发生,而这正是所需的功能安全性验证.为了进行T2T通信链路的功能安全性验证,首先,建立了非赋时有色Petri网(Colored Petri net,CPN)模型.其次,执行验证过程,并从状态空间报告和计算树逻辑语句中得出结论.最后,模型参数化,并获得数据日志文件以进行性能测试.结果表明,满足所提出的准则,T2T链路的基本设计要求没有缺陷.传输时延计算中考虑了重连、传输错误、中断情况.端到端时延小于150 ms的概率为98.106％,符合规范及现场测试结果.     

泵供液式制冷用空气冷却器制冷剂侧性能试验方法的研究

阐述了制冷用空气冷却器产品的特点,并介绍现行国内外相关标准对泵供液式制冷用空气冷却器产品的试验规定,分析已有的试验方法,提出采用制冷剂干度法作为泵供液式制冷用空气冷却器制冷剂侧的性能试验方法,探讨了试验中影响测试的关键参数,为该类产品的测试和评价提供技术支撑。     

Standard reference fibers for calibration of the optical time domain reflectometer

Calibration of optical time domain reflectometers by military and industrial users can be achieved by a number of published test procedures. For some performance parameters, a particularly convenient method for establishing measurement verification and traceability to national standards is through the use of a standard reference fiber. NIST has begun a program to evaluate such test lightguides. Prototype standard reference fibers have been characterized for spectral attenuation, group delay, group index, and length. This paper describes measurement methods and tolerances for these devices.     

秒表检定仪机/电转换器设计

针对目前秒表检定仪的检定需求和缺少检定所需机/电转换器的现状,介绍了一种用于把秒表检定仪夹具的机械信号转换成电脉冲信号的机/电转换器的工作原理、电路设计以及制作方法。并对其进行了性能测试,给出了测试数据,数据表明该转换器满足设计要求,解决了机械秒表检定仪因缺少机/电转换器无法检定的问题。     

基于GPS的圆柱度公差建模及其规范设计研究

基于GPS的恒定度和恒定类建立了圆柱度公差数学模型;基于所建立的数学模型,采用VB为开发工具在CATIA平台下进行几何变动虚拟仿真模拟,并建立了其肤面模型;基于GPS的操作和算子技术实现了圆柱度公差的规范设计。实验结果表明,基于新一代GPS的产品数字化建模及规范设计是将几何产品的功能要求、规范设计及测量认证进行数字化的统一,体现了并行设计的思想,为GPS的推广应用奠定了一定的基础。     

新一代GPS中平面度公差域的研究

在现代制造行业中,技术标准的发展成为影响制造业的重要因素,目前推行的为新一代产品几何技术规范(geometrical product specification and verification,简称GPS)。如何根据新一代GPS的要求,制定一系列标准规范已成为很多国家的重要课题。本文根据新一代GPS的要求,利用尺寸公差和几何公差的独立原则,通过对平面度相关自由度变量的确定来规范所要求的平面,并分析平面度公差域的范围;通过实例分析求解平面度公差域的变化范围,得出一种求平面度公差域范围的方法。     

Effects of mathematical models and algorithms on quantitative characterization of areal step height with optical and stylus profilometers

Step height characterization is essential for the quality control of various functional components, such as graphene and the step features of semiconductor devices. Two methods are proposed to characterize the areal step heights. The first method extends the two-dimensional characterization in the ISO specification into a three-dimensional one by extracting multiple parallel profiles. The second method calculates the step heights by projecting from the measurement points to the normal vector at the surface centroid. Mathematical models and algorithms of the two methods are introduced and validated by synthetic data. Experiments are conducted by comparing the assessment results of the two methods and of a method proposed in a previous research. The calibrated values of the standards are utilized for validation. The characterization results may differ notably or slightly, depending on the properties of the data and the algorithm.