Workpiece surface roughness measurement based on traditional machine vision technology faces numerous problems such as complex index design, poor robustness of the lighting environment, and slow detection speed, which make it unsuitable for industrial production. To address these problems, this paper proposes an improved YOLOv5 method for milling surface roughness detection. This method can automatically extract image features and possesses higher robustness in lighting environments and faster detection speed. We have effectively improved the detection accuracy of the model for workpieces located at different positions by introducing Coordinate Attention (CA). The experimental results demonstrate that this study’s improved model achieves accurate surface roughness detection for moving workpieces in an environment with light intensity ranging from 592 to 1060 lux. The average precision of the model on the test set reaches 97.3%, and the detection speed reaches 36 frames per second.

The paper presents an evaluation with the Type A and B methods for standard uncertainties of coefficients of a polynomial function of order k determined by n points obtained by measurement of input and output quantities. A method for deriving a posteriori distributions of function coefficients based on the transformation of estimator distributions without assuming any a priori distributions is presented. It was emphasized that since the correct values of the standard uncertainty of type A depend on the √ n-k-3 and not on the p √ n-k-1, therefore, with a small number of measurement points, the use of the classical approach leads to a significant underestimation of uncertainty. The relationships for direct evaluation with the type B method of uncertainties caused by uncorrected systematic additive (offset error) and multiplicative (gain error) effects in the measurements of both input and output quantities are derived. These standard uncertainties are determined on the basis of the manufacturers’ declared values of the maximum permissible errors of the measuring instruments used. A Monte Carlo experiment was carried out to verify the uncertainties of the coefficients and quadratic function, the results of which fully confirmed the results obtained analytically.

The paper presents the design of a specific type of instrumented wheelset intended for continuous measuring of lateral and vertical wheel-rail interaction forces Y and Q, in accordance with regulations EN 14363 and UIC 518. The platform is a standard heavy wheelset BA314 with an axle-load of 25 tons. The key problems of smart instrumentalization are solved by the use of the wheel’s numerical FEM model, which provides a significant cost reduction in the initial stage of development of the instrumented wheelset. The main goal is to ensure high measuring accuracy. The results of the FEM calculations in ANSYS are basis for identification of the distribution of strains on the internal and external side of the wheel disc. Consequently, the most convenient radial distances for installation of strain gauges of Wheatstone measuring bridges are determined. In the next stage, the disposition, number and ways of interconnection of strain gauges in the measuring bridges are defined. Ultimately, an algorithm for inverse determination of parameters Y and Q based on mixed signals from the measuring bridges is developed. The developed solution is validated through tests on specific examples, using a created numerical FEM model. A high accuracy of estimation of unknown parameters Y and Q is obtained with an error of less than 4.5%, while the error of estimation of their ratio Y/Q is less than 2%. Therefore, the proposed solution can be efficiently used in the instrumentalization of the considered wheelset, while the problems of its practical implementation will be the subject of further research.

Experimental methods are presented for determining the thermal resistance of vertical-cavity surfaceemitting lasers (VCSELs) and the lateral electrical conductivity of their p-type semiconductor layers. A VCSEL structure was manufactured from III-As compounds on a gallium arsenide substrate. Conductivity was determined using transmission line measurement (TLM). Electrical and thermal parameters were determined for various ambient temperatures. The results could be used for computer analysis of VCSELs. Keywords: TLM, thermal resistance, VCSEL, AlGaAs.

This article proposes an unequivocal method of labeling and numbering the cladding modes propagating in single-mode opticalwaveguides with tilted periodic structures. The unambiguous determination of individual propagating modes in this type of optical fiber is crucial for their use in sensory systems. The selection of the appropriate spectral range and mode determines the sensitivity and measuring range of tilted fiber Bragg grating (TFBG) sensors. The measurement methods proposed by individual research teams using TFBGs as transducers are usually based on the selection of specific modes. Unification of the labeling of modes and their numbering enables comparison of the basic metrological parameters of individual measurement methods and reproduction and verification of the proposed sensors and methods in the laboratories of other scientific and research centers.

The Helmholtz coil constant (k _h) is a crucial standard in magnetic moment measurement devices for permanent magnet materials. To overcome the problem of lowaccuracy of the direct-current (DC) calibration method, this study used a constant sinusoidal current in the Helmholtz coil and measured the induced voltage of the detection coil with known coil turns and coil area. Subsequently, the k _h was calculated. The noise signal deduction rate in the induction voltage of the detection coil was greater than 99%, its influence on the induction voltage is less than 0.005%, and the repeatability of the calibration results is 0.003% (1δ). The results reveal that the alternating current (AC) method and orthogonal calculation (OC) can accurately measure the valid values of the voltage signal under the influence of the spatial stray field during the calibration of k _h.

Day-boundary discontinuity (DBD) is an effect present in precise GNSS satellite orbit and clock products originating from the method used for orbit and clock determination. The non-Gaussian measurement noise and data processing in 24 h batches are responsible for DBDs. In the case of the clock product, DBD is a time jump in the boundary epochs of two adjacent batches of processed data and its magnitude might reach a couple of ns. This article presents the four GNSS (Global Navigation Satellite System) systems DBD analysis in terms of change over an 8 year period. For each of 118 satellites available in this period, the yearly value of DBD was subject to analysis including standard deviation and frequency of outliers. Results show that the smallest DBDs appear in the GPS system, the biggest – for the BeiDou space segment. Moreover, the phenomenon of changes in DBDs over time is clearly seen at the beginning of the analysed period when the magnitude and number of the DBDs were larger than for current, newest clock products