Papers by Keyword: Uncertainty of Measurement

Abstract: A three-dimensional measurement system has been set up. The digital models have been obtained using a webcam and structured light. After this, a software for measuring the digital geometries has been applied. In order to validate the digital models, the workpiece has been measured in a Laboratory of Metrology by means of a Coordinate Measuring Machine. While digital models can be obtained from multiple scan system configurations, not all of them get the same degree of accuracy. After analyzing the results, it can be determined the best condition for obtaining the digital model so that discrepancies between measurements and corresponding digital model of the workpiece are minimized. Also, it has been estimated a value of measurement uncertainty for each of the models studied.

Abstract: The basis of effective and efficient production are the measurements. Manufacturing processes should meet the accuracy requirements to produce fit products. Processes capabilities are determined (estimated) and managed by measurements and not at least the suitability of the products are also found by measurements. The measurement technique is considered as a factor associated with costs without taking part in the creation of added value. As a logical consequence is offered to reduce the measurements in order to reduce costs, according to the possibilities, but this leads to increasing of defects in production. This expensive and sometimes fatal consequences of this mentality are not reported. Processes and products are evaluated incorrectly. The number of errors and the expenses increase.

Abstract: An analytical and experimental model was proposed to determine sac volume pressure changes and fuel doses injected into the diesel engine cylinders. The model takes into account friction forces and identifies the mechanical properties of the injector. The engine performance results were analysed statistically. The results of the Lilliefors, Pearson, Shapiro-Wilk and Jarque-Bera tests provided evidence that, under certain engine operating conditions, the null hypothesis about the compatibility of the measurement data with the normal distribution can be rejected. The measurement uncertainty for the injector needle lift was estimated. The engine was powered with diesel or biofuel. The difference between the measured and the predicted fuel doses amounted to approximately 3%.

Abstract: An evaluation is conducted to the uncertainty measurement with contact type interferometer after intellectualized improvement. CMOS sensing photographing technology and computer technology are applied to the improvement of contact type interferometer. A mathematical modeling is established by taking pixel number as reading unit and gauge block length comparative measurement method as means. The purpose is to analyze the source of measurement uncertainty, estimate the standard uncertainty of input, evaluate and set forth the expanded uncertainty. The result of evaluation is superior to the level of measurement uncertainty before improvement.

Abstract: This paper discusses the relevant concepts, algorithms and the practical evaluation process on the intelligent evaluation of uncertainty of mechanical measurement with the use of computer technology (such as Computer-Aided Evaluation System). Through the optimization and integration of evaluation process, key points and regulative relationship, the author makes use of computer-aided calculation and database technology to achieve standardization of evaluation process, intelligent data analysis and automatic calculation of uncertainty.

Abstract: This paper describes the basic data process of antenna surface geometrical measurement and the quality evaluation indexes, which are surface accuracy and its uncertainty.The peak to peak value of normal deviation is used to characterize the surface accuracy,and its deviation is defined as its uncertainty.The measurement errors are given under repeated measuring conditions.Under repeated measuring conditions,the simulation method is that adding the measurement errors calculated by repeated measurement to theoretical coordinates.Under single measuring conditions, the first step is to convert the measurement data from the measuring coordinate system to the design coordinate system to get the transformation parameters;then use these parameters to convert theoretical coordinates to the measurement coordinate system;and then add measurement errors to transformed coordinates for simulation.The key point is adding measurement errors to the data which do not contain measurement errors.The simulation and actual measurement experiments of a Φ0.7 meter antenna were conducted,which showed that the method is correct.

Abstract: In this study uncertainties of measurement are evaluated for residual stresses in coatings determined by the method of measurement of the longitudinal deformation of a tubular substrate, a wire substrate and a strip substrate. Higher uncertainty was observed in the case of applying a thin coating on a strip substrate. The precision of the equipment depends on the elastic element used for measurement of the longitudinal deformation of the substrate. Residual stresses were determined in the galvanic nickel coating deposited on a tubular substrate, a wire substrate and a strip substrate from the Watts bath. Copper and brass was used as the material of the substrate. The investigated experimental system is presented.