Marine plankton is a key component of aquatic ecosystems. Development of modern and accessible tools for studying planktonic organisms is a relevant and important task. Aim of the study was to develop a device that would be highly accessible and useful for researchers of marine plankton. A prototype of a lensless microscope with an original design that utilizes digital holographic microscopy to visualize marine plankton is presented. Combination of an FDM-manufactured frame, a minimal set of optical and electronic components, and the ability to use open-source software makes it a viable alternative to conventional microscopes for studying planktonic organisms. The device is designed to work with both standard microscope slides and a flow cell, enabling automated sample processing and rapid analysis while, preserving the sample for subsequent conservation and in-depth examination using standard methods.

Nowadays, actively conducted research to study electromagnetic emission in the process of rocks, metals, composite materials’ samples loading as well as such emission in zones of rock massifs’ disintegration in sections of mine works are in progress. Measuring technique used for these purposes is aimed for recording electromagnetic emission signals mainly in the radio frequency range. The paper’s aim is to detect informative ultra-low-frequency electromagnetic radiation signals generated by a rock sample under the influence of an external load in the form of uniaxial compression created by a manual hydraulic press. The task of the study is to identify the detected low-frequency electromagnetic emission signals at the background of technogenic magnetic noise generated by a magmatic rock sample during its destruction and to establish their characteristic spectral features. The article presents results of observations of magnetic field variations using magnetic induction magnetomodulation transducers which allow recording and isolating informative signals generated by a rock sample under the influence of an external load in a laboratory experiment. The applied magnetomodulation transducers have sufficient sensitivity and resolution to record electromagnetic emission signals in the frequency range of 0.01–200 Hz, observed during the destruction of rock samples in process of their loading on the technogenic magnetic noise background. The paper describes the measurement technique, equipment and magnetometric apparatus, as well as the stages of software processing of initial data. The paper considers technique for identifying the informative ultra-low-frequency signal of recording the magnetic induction components generated by a sample of magmatic rock at its loading by uniaxial compression loading on the technogenic magnetic noise background. It was established that in case of destruction of the test sample during its loading the maximum amplitude of electromagnetic emission signals appeared in the ultra-low frequency part of the spectrum in the range of 0.3–4 Hz. Results obtained are important for studying the processes in the geological environment that generate low-frequency electromagnetic emission, as well as for investigating possible mechanisms of their generation.

Study of new kinematic parameters for strapdown orientation systems is a relevant task, since it allows increasing the accuracy and reliability of the object orientation determining under conditions of complex motion and an influence of external factors. Traditional kinematic parameters, such as Euler angles, have known limitations, for example, the problem of "gimbal lock", while new approaches to describing object rotations can provide more efficient determination of the object orientation. The aim of the work was to analyze and evaluate the applicability of the parameters (w, z) in the algorithms of strapdown orientation systems, as well as to develop and study a new scheme for combining gyroscopic and accelerometric measurements with data integration by the parameter w. Kinematic parameters (w, z) were relatively recently introduced into the theory of finite rotation, which specify the position and orientation of an object around a fixed point through two successive finite rotations. One of these rotations (angle z) characterizes the rotation of the object around one of the axes of the fixed coordinate system. The second rotation is described using a stereographic projection of the axis of the moving object onto the complex plane w = u + jv. This allows us to represent the orientation of the object as a point on this plane. Kinematic equations for the parameters (w, z) are given. Efficiency of parameters (w, z) using is shown as applied to gyroscopic strapdown orientation systems. It is shown that the kinematic equations for the function (w, z) arguments can be integrated independently of the angle z, and the general third order of the system is one unit lower than the kinematic equations in quaternions. Numerical experiments on integration of kinematic equations under the condition of constant rotation of the object with a given angular velocity of yaw and harmonic oscillations in pitch and roll angles are carried out. The modeling results are illustrated in functions of time, on the Riemann sphere and on the complex plane. Relationships are given that allow calculation of the function w(u, v) arguments using accelerometers. Stereographic projections of parameters obtained on the basis of measurements of gyroscopes and accelerometers containing instrumental errors are illustrated. A scheme for integrating gyroscopic and accelerometric data is given. This scheme differs from traditional methods because integration is performed not by pitch and roll angles but using arguments of the function w.

Modern technical means, including those using computerized components, provide new signal processing capabilities using spectral analysis. A method for calculating the velocity of an acoustic wave С from the spectrum of an echogram containing multiple reflections of acoustic pulses is described. The method is based on the detection of spectral lines spaced from each other along the frequency axis by Δf , corresponding to the pulse repetition rate repeatedly reflected from the testing object’s end. The velocity С is calculated as the average value С = LΔf, where L is the length of the acoustic axis. The search for spectral lines is carried out in the frequency domain corresponding to the working area of the input path of the registration system. To accurately determine the position of the maximum of the spectral line, it is approximated by a parabola. The velocity of the torsional wave was calculated in a batch of pipes – blanks of a plunger of a deep rod pump with lengths from 5.245 to 5.248 m, a diameter of 59 mm and a wall thickness of 13.75 mm, in the amount of 20 pieces. The sounding is performed using an electromagnetic acoustic sensor mounted on the outer surface of the pipe next to the end face. The measurement was performed with an ADNSH-P flaw detector with a receiving path bandwidth from 9.5 to 63 kHz at a level of -6 dB. The echograms were obtained at a sampling frequency of 3.75 MHz and contain 10 reflections. The torsional wave velocities of the pipes in the batch range from 3294 to 3298 m/s

Instrumental indentation is one of the effective methods for measuring the physical and mechanical properties of various materials. This paper discusses the features of testing cast iron with various forms of graphite inclusions: flake-like structure, spherical, vermicular, etc., and models that allow, based on the data of the micro-impact loading diagram of the material, to calculate the Brinell hardness HBW, the elastic modulus E and the tensile strength σ of cast iron of various grades. It is shown that the use of a set of different parameters in the calculations allows eliminating gross errors in assessing HBW caused by the influence of the graphite structure on the values of the elastic modulus and dynamic hardness. Based on experimental data, it is demonstrated that measuring the hardness of cast iron using the values of the restitution coefficient leads to a measurement error of up to 75 units. In this connection, such testing using standard dynamic hardness testers is unreliable. A stable relationship between the tensile strength and the product of hardness and elastic modulus is also confirmed. The possibility of establishing the cast iron grade (grey or spheroidal graphite iron) based on a single measurement is shown. The proposed method makes it possible the nondestructive testing of parts at industrial enterprises producing iron castings. The carried out studies prove that the developed algorithms can be used for express diagnostics of cast iron hardness using dynamic portable hardness testers with their certain modernization.

The X-ray transmission of an object to get information about its internal structure or inhomogeneities is an important method of non-destructive testing. When an object, for example, a connection of polymer pipes for transporting liquids or gases, low absorbs X-rays, the contrast of the X-ray image of the object on the photo film or on digital analogue is relatively low. The aim of the work was to develop a subtractional method for obtaining images of low X-ray absorbing objects with improved contrast using laboratory X-ray sources. In the considered method, an X-ray tube and a digital 2-D X-ray camera for X-ray beam registration are used to capture X-ray images of objects. The object is placed between the X-ray tube and the X-ray camera. The method includes capturing two digital images of the object at different angles of the object orientation to the X-ray beam axis and then processing the images by subtracting them. Images of a number of objects with low absorption of X-rays (bee, polymer mesh, rice grain) were obtained and their computer processing by image subtraction was carried out. X-ray tube BSV-17 with copper anode was used for X-ray transmission of the object, voltage at the anode of the tube – 15 kV, current – 10 mA. A Photonic Science digital X-ray camera was used to capture the X-ray image of the object. The size of the working area of the X-ray camera is 18 × 12 mm2, the number of pixels is 4008 × 2670. The object was placed close to the X-ray camera to improve the resolution of the image. Two images of the object were captured to realise the subtraction, the second image was taken with the object rotated by 5°. The contrast of the original and processed images was calculated. The analysis of the contrast of the resulting images showed that the use of the developed subtraction method allowed to increase the contrast of the image of objects with low absorption of X-rays about two times. The method is reasonably simple in comparison with the well-known phase-contrast method, and it can be used in technical diagnostics in the process of examination of plastic, polymer, composite materials and objects by X-rays.

The problem of minimising the influence of distribution laws of input values on the reliability of results in evaluation models in the field of metrology is considered. Aim of this work was to substantiate rational approaches and methods of correct solution of the problem in the case when the distribution law of input values differs from normal. Classification of variants of solutions to the problem of normality of input values in models of estimation of uncertainty of measurement method, metrological reliability of measuring instrument, etc. is presented. The complex problem of estimating the law of input quantity distribution and bringing it to normal by correcting its probabilistic characteristics is formulated. It is substantiated that such a solution of the problem will provide ‘frequency equivalence’ of empirical and normal distribution laws. Methods of solving the problem for two possible cases are considered: the input values of the model are estimated a priori and empirically. The variants of the rational solution of the problem for the case of a priori estimation of the input value of the model (type B), generally accepted in metrological practice, are considered. The main attention is paid to the case of estimating the input value of the model empirically (by type A). Chebyshev's and Vysochansky-Petunin's inequalities are taken as theoretical prerequisites for solving the problem which determine the estimates from above of the probability of deviation of a random variable from the mean without taking into account the exact form of its distribution law. A graphical method of estimating the ‘degree of normality’ of the empirical law of distribution of an input quantity and bringing it to normal by correcting its statistics is proposed. Implementation of the method assumes use of statistical packages of applied programs, for example, Statistica package, and visual comparison of the histogram of empirical distribution with the theoretical curve of normal distribution. For all possible situations an algorithm of actions is defined including analyses of the degree of mismatch between distributions and decisive rules for correcting the initial statistics of the input quantity.

Software and hardware systems for recording the underwater environment are necessary for observing the protective zones of water areas, servicing the mechanisms for developing underwater deposits and monitoring the state of offshore structures. The problem of increasing the accuracy of underwater object direction finding in conditions of underwater object detection using hydroacoustic illumination is considered in the article. For solution this problem introducing a time mark and additional modification of the measuring circuit are used. With several hydroacoustic illumination emitters it becomes possible to create a multi-angle underwater vision system that allows establishing not only the exact spatial position of underwater objects in the analyzed water area, but also the size and shape characteristics of these objects. The key task here is the task of synchronizing the registration of signals reflected by objects from different emitters. The paper describes an approach to reduce the error in the direction finding of objects caused by errors in the digitalization of the sensor signal, using the insertion of a special time mark into the signal, resampling, and more accurate synchronization of the start of the probing signal generation and the moments of digitalization of the sensor signal. The results of experimental verification of the described approach using the example of an underwater object direction finding applying stereo sensors oriented in the horizontal and vertical planes with multiple repetition of measurements are presented. It is shown that applying the proposed approach for the example given in the article increases the accuracy of direction finding by more than 8 times.

Ultrasonic flow meters are promising tool for monitoring gas flows in domestic and industrial pipelines. The aim of this work was to develop methodologies for calculating gas flow rate, as well as to develop and analyze a mathematical model using simulation in the MATLAB package for a coaxial arrangement of ultrasonic transducers, including an analysis of limitations of this approach. The base of the study was a mathematical model with a coaxial sensor arrangement, describing the propagation of ultrasonic waves in a gas flow. Input parameters were gas pressure (5 Pa and 8.5 kPa) and temperature, while the calculated parameters were flow velocity, Reynolds number, pulse transit time along and opposite the flow, difference between these two time values, and the final flow rate. The simulation was performed in MATLAB with a focus on the calculation methodology although without accounting for acoustic interference and the ultrasonic beam shape (only the central beam’s part was considered). The developed methodology allows for preliminary gas flow rate calculations and serves as a basis for further improvement including consideration of additional physical factors and adaptation for an angular transducer configuration. Key limitations of the mathematical model include: the omission of sound pressure, noise from the receiver circuit, and a simplified wave beam model. Nevertheless, the model confirmed its viability for basic scenarios.

Reliability of a gate dielectric is a key factor in its application for modern electronic devices’ electronic component base. Silicon oxide layers’ operating free-running time depends on defects’ density due to presence of hydroxyl groups and hydrogen in its volume, and broken silicon bonds at the interface with the oxide. Purpose of this work was to study effect of pulsed photon processing in a nitrogen ambient on the reliability of gate silicon oxide obtained by pyrogenic oxidation. Silicon oxide layers with a thickness of 17.7 nm were obtained by pyrogenic oxidation of single crystal silicon substrates doped with boron having resistivity of 12 Ω×cm, diameter of 100 mm, with an orientation of (100) at a temperature of 850 ℃ for 40 min. Pulsed photon processing was performed by heating in a nitrogen ambient upto 1150 ℃ in 7 s under an incoherent radiation flux from quartz halogen lamps directed at the non-working side of the substrate. The dielectric layers’ failure time was determined by accelerated testing using test MOSFET capacitors. It was shown that pulsed photon treatment of pyrogenic oxide in a nitrogen ambient lead to a 2.45–fold increase in operating free-running time due to densification of silicon dioxide and formation of Si-N bonds, which was 29.8 % longer than after processing in natural atmospheric conditions.