A measurement method of circular profile and its circumferential harmonic components with system error elimination

The research relates to the field of metrological supervision, specifically to the control of surface roughness parameters. The authors analyzed the following regulatory documents: GOST R ISO 4287-2014 “Geometrical product specifications (GPS). Surface texture. Profile method. Terms, definitions and surface texture parameters”, GOST 25142-82 “Surface roughness. Terms and definitions”, GOST 2789-73 “Surface roughness. Parameters and characteristics”, GOST 9378-93 (ISO 2632-1-85, ISO 2632-2-85) “Roughness comparison specimens. General technical conditions”, GOST 27964-88 (ST SEV 6134-87, ISO 4287 / 2-84) “Measurement of roughness parameters. Terms and definitions”, GOST 19300-86 “Instruments for measurement of surface roughness by the profile method. Contact profilographs and profilometers. Types and main parameters”, GOST R 8.651-2009 ISO “State system for ensuring the uniformity of measurements. Contact (stylus) instruments for the measurement of surface roughness. Procedure of calibration”, GOST 9847-79 “Optical instruments for surface roughness parameters measuring. Basis parameters and types”, GOST R 8.700-2010 “State system for ensuring the uniformity of measurements. Method of surface roughness effective height measurements by means of scanning probe atomic force microscope”, which regulate the measured parameters of the surface roughness, instruments that measure these parameters. In the course of a comparative analysis of the values of the parameters of existing devices and the values of the parameters of devices prescribed in the standards, a summary table was formed, and the problem of controlling nanoparameters and nanocoatings was also identified. The existing instrument base for monitoring surface roughness allows measuring parameters with high accuracy and within wide limits, but the regulatory framework on the territory of the Russian Federation is outdated and does not allow the use of some modern types of instruments. In this regard, it is necessary to update the requirements of GOSTs for the modern capabilities of technology and control over roughness parameters.

The authors have carried out a study to investigate and clarify the characteristics of purely oscillating pipe flows over the developing region. The main objective of this study is to establish the method of time-dependent velocity profiles obtained by the ultrasonic velocity profile (UVP) measurement method. First, the relationship between the test fluids and the microparticles, as reflectors of ultrasonic pulses, was investigated. In addition, the relationship between the sound speeds of the test fluids and the wall materials was studied. Second, the UVP was used to obtain the instantaneous velocity profiles in oscillating pipe flows, and the developing characteristics of the flows were analyzed. Finally, the “entrance length” (by analogy with a unidirectional pipe flow) required for oscillating pipe flows was analyzed by examining the amplitude of the harmonic spectral components of the oscillating frequency. A fast Fourier transform (FFT) is proposed as the applicable method to estimate the “entrance length”. From the Fourier transform of the velocity on the centerline, nonlinear oscillation of fluid occurs in the “entrance length” of the oscillating flows, and the viscous dissipation of the higher-order velocity harmoncis determines the entrance region. The “entrance length” can be obtained from the dissipation length of the third-order harmonic. These results prove that the UVP method is highly applicable to carry out the flow measurement in the “entrance length” of oscillating pipe flow.

Non-contact 3D edge profile measurement for die and mould model surface

We have developed a high resolution microvolume Vertical Auto Profile (VAP) method for the simultaneous measurement of cholesterol in all lipoprotein classes, including lipoprotein[a] (Lp[a]) and intermediate density lipoprotein (IDL). This method, designated as VAP-II, uses a non-segmented continuous flow (controlled-dispersion flow) analyzer for the enzymatic analysis of cholesterol in lipoprotein classes separated by a short spin (47 min) single vertical ultracentrifugation. Cholesterol concentrations of high (HDL), low (LDL), very low (VLDL), and intermediate (IDL) density lipoproteins, as well as Lp[a], are determined by decomposing the spectrophotometric absorbance curve, obtained from the continuous analysis of the centrifuged sample, into its components using software developed in this laboratory. Analysis by VAP-II is rapid and sensitive (as little as 40 microliters plasma is required per assay). The resolution of lipoprotein peaks is considerably enhanced in the present analyzer compared to the previous analyzer (VAP-I, which used the Technicon AutoAnalyzer); improvement is especially noticeable for Lp[a] and IDL. Total and lipoprotein cholesterol values obtained by VAP-II correlated well with the values obtained by Northwest Lipid Research Laboratories (NWLRL). VAP-II Lp[a] cholesterol values also correlated well with the Lp[a] mass values obtained by an immunoassay technique performed at NWLRL (r = 0.907). The reproducibility and accuracy of the method are within the requirements of the CDC-NHLBI (Centers for Disease Control-National Heart, Lung, and Blood Institute) Lipid Standardization Program.

Measurement method of surface profile by using scanning electron microscope (SEM) was applied to plastic materials, which have needed other method than the conventional ones such as optical method, needle trace method and others. The method by SEM has advantage in accurate and non-destructive measurement. Metal coat on surface is required for plastics in SEM environment. SEM using four detectors which was developed for the measurement of surface profile was used. Standard specimen of sphere made from polystyrene whose diameter was 0.03 mm was adopted. It was made obvious that sufficient time for coat such as 10 min is required for stable output intensity to derive the profile. Correlation between emission voltage of electron beam and the output intensity for the profile in terms of coating time indicates that adequate emission voltage which effectively represents the profile can be taken depending on thickness of coat. Accurate measurement is shown possible for the profile of cut surface of acryl and for the sphere of small ruby ball.

A new procedure of recording both Hugoniot parameters and stress profile is proposed to study shock characteristics of polymers in 1 GPa stress region. The assembly consists of an in-material polyvinylidene fluoride (PVDF) stress gauge element and an optical prism pin. The PVDF gauge records the shock wave stress profile, while the prism pin records the arrival of shock front at the free surface of the target. Argon laser beam is focused onto the bottom face of the prism pin placed on the free surface so as to satisfy the condition of total internal reflection. Shock velocity can be estimated from the time difference of two signals, the PVDF gauge and the prism pin. The Hugoniot state can be calculated by the shock velocity and the projectile velocity regardless of the stress profile obtained by the PVDF gauge. A typical result for polytetrafluoroethylene (PTFE) specimen is shown with the impact velocity of PTFE flyer of 295 m/s. The obtained Hugoniot point coincides very well with the published data. Precision of the method was examined in detail, and estimated to be better than 2%.

Measurement method of three-dimensional profiles of small lens with gratings projection and a flexible compensation system

Ultrasonic Velocity Profile (UVP) method for measurement of single-phase and two-phase flow in a vertical pipe has recently been developed in the Laboratory for industrial and Environmental Fluid Dynamics, Institute of Mechanics, VAST. The signal processings of the UVP method include the ultrasonic pulse Doppler method (UDM)and the ultrasonic time-domain cross-correlation (UTDC) method. For two-phase flow, simultaneous measurements of both liquid and gas are enabled by using a multi-wave ultrasonic transducer (multi-wave TDX). The multi-wave TDX is able to emit and receive ultrasound of two different center frequencies of 2 MHz and 8 MHz at the same time and position. 2 MHz frequency with beam diameter 10 mm is exploited for measurement of gas. 8 MHz one with beam diameter 3 mm is used for liquid. Measurements have been carried out for laminar and turbulent single-phase flows and bubbly counter-current two-phase flows in two flow loops using two vertical pipes of 26 mm inner diameter (I.D.) and 50 mm I.D. respectively. Based on the measured results, assessment of each method is clarified. Applicability of each method for different conditions of pipe flow has been tested. Suggestions for application of the two methods have been recommended.

Technical problems and soil profile characteristics may limit the applicability of the instantaneous profile method for field measurement of unsaturated hydraulic conductivities. A modified procedure for tensiometer installation and different methods for measuring moisture contents are discussed. Good agreement was found between moisture contents determined in situ with the neutron‐probe and those indirectly derived from moisture retention curves obtained from measurements of large core samples in a closed assembly. Sloping soils with slowly permeable horizons or with lateral water movement cannot be characterized adequately with this method. The use of the crust test procedure is recommended.

The system error of photoelectric theodolite includes Visual axis error, horizontal axis error, vertical axis error, Azimuth orientation error, elevation zero error; This paper ratiocinates the formula of Azimuth orientation error, elevation zero error and Visual axis error of Photoelectric theodolite of T type by triangle relation in space. Photoelectric theodolite of U type with main visual axis and auxiliary visual axis shoots images and inverse images of marks to obtain system error data. Error is less than 0.4 second by comparing error data of auxiliary visual axis with error data of main visual axis and the precision of two methods is identical. It has been validated that the method of error measurement of photoelectric theodolite of T type is right.

The hydrodynamic characteristics of a free-floating moonpool encountering the gap resonances are investigated based on the constrained interpolation profile method in numerical wave tank. This paper mainly concentrates on the influences of the moonpool's motion responses and the incident-wave height on the gap resonances in the free-floating moonpool. Numerical results demonstrated that the heave response significantly changes the frequency and the magnitude of the linear gap resonance, while the roll motion influences more on the vertical wave loads and the wave responses in the fluid field. The heave and roll response of the free-floating moonpool are generally independent. Moreover, the magnitudes of the nonlinear gap resonances have the tendency of catching up and exceeding the linear gap resonance as the incident-wave height increasing for the free-floating moonpool, which is the consequence of the higher-order harmonics driven by the nonlinear processes and the linear secondary resonant region induced by the heave response. Based on the wavelet transform, it could be observed that the amplified harmonic component usually takes more time to be fully developed than other harmonic components during the development of its corresponding nonlinear gap resonance.

This study presents the exponential distribution optimization (EDO) technique for tuning the proportional-integral-derivative (PID) controller parameters in combined load frequency control (LFC) and automatic voltage regulation (AVR) for both single- and two-area electrical power system models. The objective is to enhance system performance by minimizing frequency and voltage deviations. The proposed approach leverages widely adopted objective functions, namely, the integral time squared error (ITSE) and the integral time absolute error (ITAE) to effectively reduce control errors while improving system stability and transient response. The EDO algorithm iteratively refines PID parameters by selecting optimal values from evolving solution populations, with system disturbances introduced to evaluate robustness under varying operating conditions. Simulation results demonstrate significant improvements, including a 16.52% reduction in LFC undershoots and a 33.3% improvement in AVR steady-state error in single-area systems, and up to 13.2% faster settling times in two-area systems. The EDO-based controller achieves faster dynamic responses, smoother operation, and complete elimination of steady-state errors while maintaining balanced frequency overshoot and minimized transient oscillations. Comparative analyses confirm the method’s superiority over established optimization techniques. A comprehensive robustness further validates the reliability and effectiveness of the EDO-tuned PID controller, underscoring its strong potential for ensuring power system stability.

The article discusses the importance of timely detection and elimination of hardware errors in information systems, as well as tools that can help maintain their uninterrupted operation. Particular emphasis will be placed on monitoring hardware components and the timely detection of failures that may lead to data loss or reduced overall performance.

We present a three-wavelength dual differential absorption lidar (dual-DIAL) method with which one can obtain an accurate stratospheric ozone profile in the presence of volcanic aerosols. Results of theoretical analysis and comparisons with conventional DIAL and backscatter correction methods show that the three-wavelength dual-DIAL method greatly reduces the effect of volcanic aerosol on stratospheric ozone measurements, and system errors that are due to aerosols are kept at a low level. In addition this method is almost completely insensitive to wavelength dependence of aerosol backscatter, its spatial change, and spatial inhomogeneity of aerosol loading. Therefore, one does not need to know detailed information about these aerosol properties, and accurate stratospheric ozone profiles can be obtained directly from lidar return signals. An example of the experimental result indicates that the proposed method is effective.

The methodologies for calculating exhaust emissions and fuel consumption, which are given in the normative documents, do not take into account the fact that vehicles equipped with liquefied petroleum gas (LPG) or compressed natural gas (CNG) systems are fueled with petrol after a cold start. When calculating exhaust emissions and fuel consumption of LPG or CNG-powered vehicles, it is assumed that they result from the combustion of gaseous fuel only. This simplification leads to an incorrect determination of the emissions and fuel consumption values, as the formulas for calculating these values differ depending on the fuel type. This article presents the results of tests aimed at checking how that factor affects the value of emissions and fuel consumption calculated in the driving cycles used in the type-approval tests. In order to estimate the error resulting from this simplification, the tests of exhaust emissions and fuel consumption of a vehicle equipped with an LPG system were carried out. The tests were carried out on a chassis dynamometer in the worldwide harmonized light vehicles test cycle (WLTC) used in the type approval tests. In the tested vehicle, the CO, total hydrocarbons (THC), NOx and CO2 emissions calculated with the normative method were approx. 7% lower than the values calculated with the corrected method. For this reason, there is a need to develop a measurement method that allows for a separate analysis of the phase in which the vehicle is fueled with gasoline. This will allow the elimination of errors in the current normative method of calculating pollutant emissions from the exhaust system and fuel consumption of vehicles fueled with gaseous fuels.