The computational efficiency of semi-explicit and semi-implicit multistep methods of numerical integration when applied to simulation of seven-dimensional stiff system of ordinary differential equations is studied. A general description of semi-explicit and semi-implicit Adams-Bashforth-Moulton methods is presented. Performance of solvers based on investigated methods of the fourth order is compared to that of solvers using Adams methods and the backward differentiation formula. The computational experiments carried out confirm that the proposed modifications of the Adams-Bashforth-Moulton method demonstarate the best performance among the considered multistep schemes, when simulating with a constant and variable integration step. It is assumed that the obtained results can be used to speed up numerical modeling in modeling subsystems of computer-aided design systems.

The problem of controlling the movement of a mobile robot along a given smooth trajectory with a desired speed under the conditions of uncertainty of the mathematical model is analyzed. Two approaches to determining the minimum distance from the robot to the trajectory are considered: an exact analytical calculation and application of a nonlinear observer which guarantees the convergence of current estimate to the true value in an arbitrarily short time. A motion control algorithm is presented based on the sequential compensator method, which ensures a limited deviations of the robot from a given trajectory.

Construction of a small spacecraft cluster intended for remote sensing of the Earth is considered. Parameters of a model of the orbital construction are analyzed. The importance of accounting for the minimum distance of the straight line connecting low-orbit small spacecrafts, from the Earth's surface when creating the cluster is substantiated. The methods of half partition and golden section are used to determine the functions of collecting and transmitting information to spacecraft and the order of their location in the orbit. The expediency of using the golden section method to ensure the best parameters of the small spacecrafts orbital cluster are substantiated. The improvement of the parameters consists in a 6–8 % decrease in the number of transmitting spacecrafts in the orbit. Since the transmitting devices are directly connected with ground data receiving and processing points, their reduction reduces the dependence of the communication sessions of the orbital cluster with the transmitting spacecrafts number, and ultimately leads to an increase in the stability of the operation of the entire small spacecraft orbital group.

Dynamic models of piezo energy harvesters (PEH) based on thin single-layer piezoelectric elements (PE) are considered. Using an equivalent circuitry of the piezoelectric harvester, differential equations are obtained and the transfer functions of the PEH, which relate the input variable (the load force on the PE) to the output variables (the voltage and current of the load capacitor), are found. Analytical studies of steady-state and transient processes in PEH under typical loading forces (pulsed, stepped, harmonic) are carried out. It is shown that a sufficient condition for stable piezoelectric energy harvesting, which consists in a continuous charge of the load capacitor, is a non-zero acceleration of the load force on the PE. The influence of the parameters PEH – equivalent values of resistance, capacitance and inductance of PE, resistance of conductors and diodes of the rectifier, capacitance of the load capacitor, load resistance – on transient processes is considered. The estimate of the maximum achievable PEH power at a monoharmonic load force on the PE is obtained. The data of analytical calculations and experimental studies of the piezoelectric energy harvesting in PG with a single-layer disk PE in the load force jump and meander modes are presented. The results of the research are intended for the design of PEH with a known range of loading forces.

A method is considered to minimize the influence of errors caused by misalignment of the shafts of the engine and the control object, in the presence of a mechanical transmission as part of the executive electric drive, when the control system is organized along a feedback loop closed by the sensor of the angular position of the rotor of the engine. Peculiarities of the low-speed precision electric drive design are described on the example of executive electric drive of the power gyroscopic complex of a spacecraft orientation control system. Experimentally obtained difference in the readings of the angular position sensors located on the axes of the executive motor and the control object, reduced to the control object, shows the influence of the misalignment of the mechanical transmission. Results of mathematical modeling are presented, demonstrating the influence of the misalignment of the mechanical transmission on the angular velocity exerting by the electric drive in the case of a closed feedback loop with angular position sensor located on the shaft of the executive motor. A method for compensating for mechanical transmission misalignment is described and the results of resulting angular speed of rotation when a control system using this method is implemented for the electric drive are presented. Based on the results of mathematical modeling, it is shown that the use of the proposed compensation method can significantly reduce the error in resulting angular velocity of the control object. The advantage of the proposed method is that its implementation affects only the software of the electric drive without the need to modify the hardware.

An algorithm of spacecraft lithium-ion battery state of charge estimation without current sensor is presented. It is shown that average current flowing through the battery over the discharge period may be estimated based on a model of battery state of charge. The input data for the algorithm are an estimate of the average battery voltage for the period from the beginning of the discharge to the current time and the measured voltage of the batteries. The calculated average discharge current makes it possible to calculate the given and remaining capacity of the battery. The algorithm accuracy check is performed using the NASA randomized battery usage data set. The error in assessing the degree of charge of a lithium-ion storage battery comprises from 2.2 to 11%.

The structure of an optoelectronic system for ensuring the separation of fruits of complex shape according to their geometric parameters is proposed. A genetic algorithm developed to solve the problem of optimizing location of the video cameras in the corresponding segments of space according to the criterion of ensuring the required error in determining the fruit shape is described and tested. Simulation modeling of the system performance with four video cameras shows that for restoring the shape of fruits with an error of 18 microns, it is sufficient to use a population of 30 individuals in the genetic algorithm. Parameters of spatial orientation of the four video cameras located at a distance of 500 mm from the fruit are found for estimated error of 3.5 μm in restoring three-dimensional coordinates of the points on the fruit surface.

Biological objects are investigated by the method of geometric optics. Optical scheme of developed device is shown, in which an axicon pair of conical lenses is used. A triangulation method is described, the relationship of the aperture angle of illumination and the angle of observation with the measurement error is given. A way to increase the measurement range is found. The measurement error with the presented device is not higher than 0.1 µm, and the measurement range is 0–100 mm. Metrological data obtained from experiments with human skin samples of different age groups are described.

A photoionization generator – detector of gases and vapors is developed. The instrument design, principle of operation, and performance are discussed. The possibility of using the detector in a gas chromatograph with a capillary column, for example, for medical purposes (especially in respiratory diagnostics for detection of various diseases) is considered. The detector diagram is demonstrated, elements of the chromatograph are described in detail. Presented results of experiments confirm applicability of photoionization generator – detector in capillary gas chromatography for the analysis of liquid multicomponent media.

The pathology of the lacrimal duct unites a whole group of diseases that affect the work of the entire visual apparatus. To assess their patency, the use of radionuclide diagnostic techniques is allowed. However, there are several limitations associated with the small size of the objects under study and with the dose load on the lens of the eye. The latter depends on the activity of the injected radiopharmaceutical, the patency of the lacrimal ducts and the necessary counting statistics to obtain a reliable diagnostic result. The possibility of using the developed portable radiometric system (PRS) in the dynamic scintigraphy mode for dacryoscintigraphic studies of the lacrimal system is studied. To achieve the best ratio "diagnostic result / dose load on the lens", an algorithm for calculating the optimal activity of the injected drug is proposed. For experimental verification of the presented method of dacryoscintigraphy using PRS, a phantom model of the lacrimal system is developed and manufactured. Comparative testing of the PRS and a single-photon emission computed tomography showed that with dacryoscintigraphy, the PRS will have a higher radiation detection efficiency. The increased efficiency of registration either can increas the number of typical dacryoscintigraphic examinations or significantly reduce the time windows in the PRS and, therefore, investigate the finer structure of dynamic curves. исследовать более тонкую структуру динамических кривых.

A poly-model description of the problem of control over information processes in a distributed information and computer network with a reconfigurable (configurable) structure, has been developed. The information processes under investigation include the processes of data receiving, transmitting, processing, and storing. In addition, it is assumed that due to the limited bandwidth of the data transmission channels, as well as the computing resources of the network, data losses in the specified network are possible. The proposed poly-model description includes static and dynamic models of control of information processes in information and computer network. Methods of mathematical programming (for a static model) and the method of local sections (for a dynamic model) are used to calculate indicators of the quality of control over the information processes. Information on software implementation of the developed model-algorithmic support for solving problems of calculating, analyzing, and optimizing the quality indicators of the information processes is presented.