Volumen 14 (2014): Edición 1 (February 2014)

Nowadays, simulators facilitate tasks performed daily by the engineers of different branches, including coordinate metrologists. Sometimes it is difficult or almost impossible to program a Coordinate Measuring Machine (CMM) using standard methods. This happens, for example, during measurements of nano elements or in cases when measurements are performed on high-precision (accurate) measuring machines which work in strictly air-conditioned spaces and the presence of the operator in such room during the programming of CMM could cause an increase in temperature, which in turn could make it necessary to wait some time until conditions stabilize. This article describes functioning of a simulator and its usage during Coordinate Measuring Machine programming in the latter situation. Article also describes a general process of programming CMMs which ensures the correct machine performance after starting the program on a real machine. As an example proving the presented considerations, measurement of exemplary workpiece, which was performed on the machine working in the strictly air-conditioned room, was described

In air/oil lubrication systems, the flow parameters, e.g., flow pattern, liquid film thickness, and air/oil flow rate, are of great importance to the transportation efficiency. In most cases, the on-going two-phase flow is annular flow with the oil moving along the tube wall and the air travelling at high speed in the center. This usually results in the formation of a thin oil film, the thickness of which is a key parameter determining the efficiency of the lubrication system. As the oil film thickness of the on-going air/oil flow varies dynamically, there is actually no applicable method for a non-intrusive test. In this paper, the use of electrical capacitance tomography (ECT) to investigate the air/oil flow has been studied. Capacitance measurements are made from an externally mounted electrode array in a non-invasive and non-intrusive manner. Both average and distributed oil film thicknesses can be calculated from the reconstructed ECT images. Simulation and experimental results show that the ECT technique can provide satisfactory results of online oil film thickness estimation

This paper focuses on the calibration of apertures for rectangular waveguides using open-short-load (OSL) standards and transmission-line (TL) approaches. The reflection coefficients that were measured using both calibration techniques were compared with the coefficients acquired using the thru-reflect-line (TRL) method. In this study, analogous relationships between the results of OSL calibration and TL calibration were identified. In the OSL calibration method, the theoretical, open-standard values are calculated from quasi-static integral models. The proposed TL calibration procedure is a simple, rapid, broadband approach, and its results were validated by using the OSL calibration method and by comparing the results with the calculated integral admittance. The quasi-static integral models were used to convert the measured reflection coefficients to relative permittivities for the infinite samples and the thin, finite samples

We demonstrate the interferometer-based approach for nanoscale grating Critical Dimension (CD) measurements and prove the possibility to achieve no worse than 10 nm accuracy of measurements for 100 nm pitch gratings. The approach is based on phase shift measurement of light fields specularly reflected from periodical pattern and adjacent substrate with subsequent comparison between experimental and simulation results. RCWA algorithm is used to fit the measured results and extract the CD value. It is shown that accuracy of CD value measurement depends rather on the grating’s CD/pitch ratio than its CD value

The article examines: (i) the reasons of error due to thermoelectric inhomogeneity of electrodes of thermocouples acquired during prolonged use; (ii) the neural network method of error correction based on a generalization of verification results in several temperature fields; (iii) the method of investigating the impact of changing the speed of the conversion characteristic drift of thermocouple on error correction; (iv) results of this investigation. It is shown that residual error for type K thermocouples at the 5 % level of significance does not exceed μ±0.46 oС and one at the 10 % level of significance does not exceed ±0.25 °С

The flexural mechanical strength was measured at room and elevated temperatures on green ceramic samples made from quartz electroporcelain mixture. An apparatus exploited the three-point-bending mechanical arrangement and a magazine for 10 samples that are favorable at the temperature measurements from 20 °C to 1000 °C. A description of the apparatus from the point of possible sources of uncertainties is also given. The uncertainty analysis taking into account thermal expansion of the sample and span between the supports is performed for 600 °C. Friction between the sample and supports as well as friction between mechanical parts of the apparatus is also considered. The value of the mechanical strength at the temperature of 600 °C is 13.23 ± 0.50 MPa, where the second term is an expanded standard uncertainty. Such an uncertainty is mostly caused by inhomogeneities in measured samples. The biggest part of the uncertainty arises from the repeatability of the loading force which reflects a scatter of the sample properties. The influence of the temperature on the uncertainty value is very small

In this paper, we focus on CMF signal processing and aim to resolve the problems of precision sharp-decline occurrence when using adaptive notch filters (ANFs) for tracking the signal frequency for a long time and phase difference calculation depending on frequency by the sliding Goertzel algorithm (SGA) or the recursive DTFT algorithm with negative frequency contribution. A novel method is proposed based on feedback corrected ANF and Hilbert transformation. We design an index to evaluate whether the ANF loses the signal frequency or not, according to the correlation between the output and input signals. If the signal frequency is lost, the ANF parameters will be adjusted duly. At the same time, singular value decomposition (SVD) algorithm is introduced to reduce noise. And then, phase difference between the two signals is detected through trigonometry and Hilbert transformation. With the frequency and phase difference obtained, time interval of the two signals is calculated. Accordingly, the mass flow rate is derived. Simulation and experimental results show that the proposed method always preserves a constant high precision of frequency tracking and a better performance of phase difference measurement compared with the SGA or the recursive DTFT algorithm with negative frequency contribution

Recent demand on the measurement resolution of precise positioning comes up to tens of picometers. Some distinguished researches have been performed to measure the displacement in picometer order, however, few of them can verify the measurement performance as available tools in industry. This is not only because the picometer displacement is not yet required for industrial use, but also due to the lack of standard tools to verify such precise displacement. We proposed a displacement reduction mechanism for generating precise displacement using torsional leaf spring hinges (TLSHs) that consist of four leaf springs arranged radially. It has been demonstrated that a prototype of the reduction mechanism was able to provide one-nanometer displacement with 1/1000 reduction rate by a piezoelectric actuator. In order to clarify the potential of the reduction mechanism, a displacement reduction table that can be mounted on AFM stage was newly developed using TLSHs. This paper describes the design of the reduction mechanism and the sub-nanometer displacement performance of the table obtained from its dynamic and static characteristics measured by displacement sensors and from the AFM images