The purpose of the study, the materials of which are presented in this paper, is to disclose modern approaches to the determination of elevations of terrain points on topographic plans and maps. This is crucial when constructing digital models of relief and terrain, when using computer systems for digital cartography and automated map generation. According to the analysis of global trends, precise determination of point elevations is of paramount importance when reconnoitring terrain during the preparation of planning and elevation justifications; when performing various types of geodetic works for the design and construction of underground utilities (water supply, sewage, gas pipelines, heating mains, electrical cables), as well as in military affairs when deploying military equipment. This is especially relevant today, when technologies related to the use of computer systems for digital cartography are widely used. Errors in the graphical determination of terrain elevations on topographic plans and maps, which may arise due to errors in drawing and graphical representation of contours, errors due to displacement of elevations in the planimetric determination of point positions, as well as errors during inaccurate interpolation of contours, can lead to a decrease in the economic efficiency of geodetic works by reducing the overall accuracy of the works. The paper proposes a method that allows obtaining preliminary data of acceptable accuracy for performing geodetic works and makes it possible to abandon expensive and inefficient instrumental measurement methods. As a result of the study, the dependencies of errors in the graphical determination of elevations on topographic plans and maps under various relief conditions and scales of topographic plans and maps were calculated. The proposed method allows obtaining preliminary necessary data for performing geodetic works with an error that does not exceed the permissible value. Formulas for calculating error values depending on the different types of terrain complexity, as well as different scales of topographic plans and maps, are proposed. To validate the proposed method and confirm its accuracy, additional field studies were conducted, the main task of which was to perform visual measurements to determine the elevations of selected points. Based on the results obtained, it can be concluded that the difference in the elevations of points taken from plans and determined by visual levelling does not exceed the permissible limits.
The paper studies the influence of additional structural elements on the light and color characteristics of an LED luminaire. The main attention is paid to the analysis of the role of specialized optical lenses, limiting plates and a protective polycarbonate diffuser in the formation of lighting parameters of radiation. The key facet of the paper is the evaluation of the influence of a polycarbonate diffuser on the quality of color rendering. For this purpose, a modern approach to colorimetric evaluation was applied in accordance with the CIE 224:2017 recommendations and the ANSI/IES TM-30 standard using the color rendering accuracy index Rf. It is shown that polycarbonate material partially absorbs the short-wave component of the LED radiation spectrum, which leads to a decrease in the luminous flux within 5-12%. In the absence of a complete restoration of the real spectral distribution of radiation, comparative analysis using reference LED templates is an effective and promising colorimetric approach. It allows one not only to objectively evaluate the quality of light, but also to predict the influence of design changes on the color characteristics of luminaires at the design stage of modern lighting systems. As a result of applying a polycarbonate diffuser, the increased Rf index value provides a better correspondence of color rendering indicators to subjective visual perception compared to an open LED module.
The paper analyses available approaches to determining effective degrees of freedom when evaluating the expanded uncertainty of correlated measurements: the GUM approach, the expressions proposed in the papers by R. Willink and H. Kastrup, the approach proposed by the Authors, and the reduction method. The simplest mathematical model with two input quantities was chosen as a test model, the results of which from n simultaneous observations, distributed according to the normal law, are assigned only to Type A uncertainties. For this model, the measurand corresponds to a bivariate t-distribution with (n-1) degrees of freedom. The analysis suggested that the Welch-Satterthwaite equation presented in the GUM approach, as well as the expressions proposed in the papers by R. Willink and H. Kastrup, lead to an effective degree of freedom that differs from (n-1) when the correlation coefficient and the ratio of the input quantity uncertainty contributions vary, demonstrating the unreliability of these expressions. It was shown that the number of degrees of freedom (n-1) is obtained using the Authors' proposed method and the reduction method developed specifically for correlated measurements. The paper presents an example of an extended uncertainty evaluation for resistor resistance measurements using the voltmeter-ammeter method, demonstrating the agreement between the results obtained using the method proposed by the Authors and the reduction method.
The measurement of low voltage up to 1000 V with a frequency of up to 1 MHz is crucial in electricity and magnetism. The AC/DC voltage transfer difference (AC/DC difference) is a critical metrological characteristic of the reference thermal converter. The metrological traceability of electrical voltage measurements shall be validated by either comparison with other national standards or calibration using standards with lower measurement uncertainty. Since, in practice, the period between comparisons of national standards is not always appropriate, calibration is more suitable for establishing metrological traceability if a primary standard is not introduced. This paper shows the way how to address the issue of irregular calibration of the component (Fluke 792A instrument) of the state standard DETU 08-07-02, detailing the approach to disseminate the reference AC/DC difference. Features of the mentioned measuring instrument are outlined, and ranges of voltage comparison are analysed, including one more suitable for being a link between the AC/DC difference and other measurement ranges. The diagram for disseminating the reference AC/DC difference demonstrates the proposed approach. The applied approximation allows one to deduce relations between the output quantity (AC/DC difference) of the studied standard and the input voltage depending on frequency for each input range. Using the mathematical processing program Microsoft Excel, the approximate equations were obtained, including polynomial dependence coefficients and coefficients of determination. In addition, by extrapolating the results of comparing the AC/DC differences it is possible to observe the potential bias in the controlled quantity.
Based on the analysis of the available verification system of measuring instruments, the inexpediency of a fixed value of inter-verification intervals has been established, and recommendations for the implementation of a different approach to changing the values depending on the operation time have been substantiated. Establishing the patterns of changes in the values of reliability and accuracy indicators over time allows one to increase the metrological reliability of measuring instruments, as well as the operational reliability of radio-electronic devices due to correct assessment of their real technical condition during maintenance and current repairs. The paper for the first time studies the option of reducing the verification intervals of measuring instruments to ensure the required level of their metrological reliability depending on the given value of the complex reliability indicator or the accuracy of measurements of the parameter values of radio-electronic instruments when assessing their technical condition during maintenance or current repairs. The results obtained can be used for versatile determination of verification intervals of both analogue and digital measuring instruments.
