System Parameters Research Articles

On the motion of a dynamically symmetric satellite in one case of multiple parametric resonance

The paper studies the motions of a dynamically symmetric satellite (rigid body) relative to the center of mass in the central Newtonian gravitational field on a weakly elliptical orbit in the neighborhood of its stationary rotation (cylindrical precession). We consider the values of the parameters for which, in the limiting case of a circular orbit, one of the frequencies of small linear oscillations is equal to unity and the other is equal to zero, and the rank of the coefficient matrix of the linearized equations of the perturbed motion is equal to two, as well as a small neighborhood of this resonant point in the three-dimensional space of parameters. The resonant periodic motions of the satellite, analytical in fractional powers of a small parameter (the eccentricity of the orbit of the satellite's center of mass), are constructed. A rigorous nonlinear analysis of their stability is carried out. The methods of KAM theory are used to describe two- and three-frequency conditionally periodic motions of a satellite, with frequencies of different orders in a small parameter. A number of general theoretical issues concerning the considered multiple parametric resonance in Hamiltonian systems with two degrees of freedom that are close to autonomous and periodic in time are discussed. Several qualitatively different variants of parametric resonance regions are constructed. It is shown that in the general case the nature of nonlinear resonant oscillations of the system is determined by the first approximation system in a small parameter.

Delayed optical feedback-regulated artificial soliton molecule in a femtosecond optical parametric oscillator

Soliton molecules (SMs) play a crucial role in nonlinear optical systems, enriching our understanding of nonlinear science through the study of their interaction dynamics. While passively mode-locked fiber lasers offer an efficient platform for generating diverse types of SMs, the complex internal dynamics of the laser often pose challenges in achieving predetermined temporal separations between SMs. Here, we implement a delayed optical feedback technique within a femtosecond optical parametric oscillator, enabling the generation of SMs with precise and controllable temporal separations. A theoretical model, which models the intracavity iterations of the signal with a simplified Ikeda map, is proposed to study the impact of parametric gain, intracavity feedback delay, and cavity length on the internal separations of the SMs. Our experimental results confirm that adjusting the cavity length allows for producing desired temporal separations within SMs. To reveal the evolution dynamics of the SMs, we further develop a rigorous numerical model using the carrier-resolved Forward Maxwell Equation, which is capable of modeling ultra-broadband complex dynamics based on a single equation without relying on the slowly-varying envelope approximation. The numerical model unveils the rich formation dynamics of the SMs at various separations, which confirms the critical role of the gain window provided by the pump. This work opens up new opportunities for the on-demand generation of SMs and provides valuable insights into the complex dynamics in femtosecond optical parametric oscillator systems with optical delayed feedback.

Bayesian stability and force modeling for uncertain machining processes

Accurately simulating machining operations requires knowledge of the cutting force model and system frequency response. However, this data is collected using specialized instruments in an ex-situ manner. Bayesian statistical methods instead learn the system parameters using cutting test data, but to date, these approaches have only considered milling stability. This paper presents a physics-based Bayesian framework which incorporates both spindle power and milling stability. Initial probabilistic descriptions of the system parameters are propagated through a set of physics functions to form probabilistic predictions about the milling process. The system parameters are then updated using automatically selected cutting tests to reduce parameter uncertainty and identify more productive cutting conditions, where spindle power measurements are used to learn the cutting force model. The framework is demonstrated through both numerical and experimental case studies. Results show that the approach accurately identifies both the system natural frequency and cutting force model.

A Hybrid Photo-Catalytic Approach Utilizing Oleic Acid-Capped ZnO Nanoparticles for the Treatment of Wastewater Containing Reactive Dyes

In pursuit of overcoming Fenton oxidation limitations in wastewater treatment, an introduction of a heterogeneous photocatalyst was developed. In this regard, the current work introduces ZnO nanocrystals that were successfully prepared via a thermal decomposition technique and then capped with oleic acid (OA). The synthesized ZnO-OA and the pristine ZnO were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM). Then, the study introduces the application of such materials in advanced oxidation processes, i.e., a Fenton reaction to treat dye-containing wastewater. Synthetic wastewater that was prepared using Reactive Blue 4 (RB4) was used as a simulated textile wastewater effluent. Fenton’s oxidation was applied, and the system parameters were assessed using the modified Fenton’s system. The synthesized samples of ZnO were characterized by a recognized wurtzite hexagonal structure. The surface modification of ZnO with oleic acid (OA) resulted in an increase in crystallite size, lattice parameters, and cell volume. These modifications were linked to the efficient capping of ZnO nanoparticles by OA, which further improved the dispersion of the nanoparticles, as demonstrated through SEM imaging. The optimum conditions of ZnO- and ZnO-OA-synthesized modified Fenton composites showed 400 mg/L and 40 mg/L for H2O2 and the catalyst, respectively, at pH 3.0, and within 90 min under UV irradiation the maximal dye oxidation reached 93%. The catalytic performance at its optimal circumstances was in accordance with a pseudo-second-order kinetics model for both ZnO-OA- and the pristine ZnO-based Fenton’s systems. The thermodynamic parameters, including the enthalpy (ΔH′), the entropy (ΔS′), and Gibbs free energy (ΔG′) of activations, were also checked, and their values settled that both ZnO and ZnO-OA Fenton systems are non-spontaneous in nature. Furthermore, the reaction signified for processing at a low energy barrier condition (10.38 and 31.38 kJ/mol for ZnO-OA- and the pristine ZnO-based Fenton reactions, respectively).

Well-posedness and stability result for carbon nanotubes Timoshenko beams with second sound

This article presents a comprehensive study of the well-posedness and stability results for double-wall carbon nanotubes (DWCNTs) modeled as Timoshenko beams, incorporating the thermoelasticity of the second sound type and frictional damping. We establish the well-posedness of the system using the semigroup technique. Additionally, we demonstrate that the combined effects of thermal dissipation, governed by Cattaneo's law, and frictional damping lead to exponential stability of the system without imposing any restrictions on the system's parameters. The stability result is demonstrated using the multiplier method. Our result is novel and significantly improves existing results in the literature regarding the stability of DWCNTs.

Forecast assessment of water regime efficiency and changes in water consumption on drained lands of Western Polissia of Ukraine in a changing climate

The article presents forecast data on the impact of changing weather and climatic conditions on evaporation and water demand on the drained lands of Western Polissia of Ukraine in different periods of their development. These data are the basis for the development of appropriate adaptive measures aimed at reducing the negative impact of changing weather and climate conditions on drained lands and increasing the efficiency of their use. Computer simulation modeling of various climatic scenarios was planned to accomplish the objective. The forecast was made through a machining experiment based on the implementation of a corresponding complex of forecast-simulation models regarding the main regime-technological variable parameters of drainage systems, local climatic conditions, water regime, water management technologies, and productivity of drained lands for schematized natural, agrotechnical, and meliorative conditions. Vegetation values of total evaporation and water demand formation of drained lands were determined for the long-term forecast module of water supply regarding variable climatic and agro-meliorative conditions. The technological efficiency of different irrigation technologies (subsoil irrigation, sprinkler irrigation) of drained lands was evaluated. The research showed that in the Western Polissia of Ukraine, the water supply module for irrigating drained lands varies significantly depending on the type of crops, drained soil (mineral, peat), irrigation technologies, and heat and moisture supply conditions during the vegetation period. It has been experimentally determined that under current climatic conditions, the value of the water supply module is 2.9 times higher than the existing recommended design values, and under the predicted conditions of their change, this excess is 5.2 times. At the same time, the water demand of cultivated crops increases almost 2–3 times and determines the need to increase water consumption for moistening drained lands in conditions of sufficient water shortage. It has been established that the main content of the necessary adaptive measures is to increase the moisture availability of soils with regulated water regime by switching from periodic to regular moistening of them through the use of appropriate resource-saving technologies for regulating the water regime.

Oscillatory and negative magnetoresistance in granular nanowires of superconducting NiBi3

Local fluctuations in the superconducting order parameters in granular systems show interesting magnetotransport behavior, particularly relevant to superconducting nanowires. Kivelson and Spivak [Phys. Rev. B 45, 10490 (1992)] have shown that fluctuations in density and signs of supercurrent can lead to oscillating and negative magnetoresistance (MR). Here, we present magnetoresistance measurements of 100 nm wide NiBi3 superconducting nanowires, patterned by focused ion beam lithography, from granular NiBi3 films containing different concentrations of magnetic Ni impurities. The nanowire containing a higher concentration of Ni impurity showed oscillations in MR and simultaneously exhibited negative MR in certain temperature and field ranges. None of these effects were observed in the nanowire with nearly no Ni impurities. Unlike earlier experiments, we argue that excess magnetic Ni impurities in the nanowire realize a case of simultaneous magnitude and sign fluctuations in local order parameter, leading to MR oscillations and MR sign reversal in the same system, as discussed by Kivelson and Spivak. This result is important in the context of transport in superconducting quantum circuits.

System frequency response model and droop coefficient setting considering renewable energy participation in frequency regulation

The highly uncertain and uncontrollable power output of renewable energy sources (RES), when integrated into power systems at high penetration levels, reduces system inertia and introduces uncertain changes in system structure, parameters, and frequency response characteristics. This renders traditional frequency regulation analysis methods and frequency response models inapplicable, lacking a generalized model to describe renewable energy’s participation in frequency regulation. Thus, this paper proposes a method where RES utilize suitable means to reduce load, thereby contributing to frequency regulation. Furthermore, employing Virtual Synchronous Machine (VSM) technology, these renewable energy units emulate the inertia and droop characteristics of Synchronous Generators (SG), enabling their equivalent modeling alongside traditional generators within a single-machine aggregate model. An SFR (System Frequency Response) model integrating renewable energy’s frequency regulation has been established. This model enables the analysis of the relationships between the system’s equivalent droop coefficient and the frequency nadir, nadir time, and quasi-steady-state point. Furthermore, the required equivalent droop coefficients are proposed for various sending-end system capacities and operating conditions. Finally, the model’s validity and accuracy are confirmed through a modified WSCC 4-machine 10-bus system, offering theoretical underpinnings for stable system operation and optimized operational planning.

The relationship of macular vessel density and foveal avascular zone with pulse wave velocity and central blood pressure in healthy adults: Persian cohort study

BackgroundTo evaluate the correlation of macular vessel density (VD) and foveal avascular zone (FAZ) parameters measured on optical coherence tomography angiography (OCTA) with systemic arterial stiffness using pulse wave velocity (PWV), pulse wave analysis, arterial age, and central blood pressure (CBP) measurements in healthy subjects.MethodsIn a comparative, cross-sectional, observational study, healthy adults who participated in the PERSIAN Cohort study at Mashhad University of Medical Sciences were included in this study. The study involved using a spectral domain OCTA device to obtain 3 × 3 and 6 × 6 mm scans of the macular superficial capillary plexus (SCP) VD, deep capillary plexus (DCP) VD, and FAZ vascular analysis. Additionally, we used the SphygmoCor XCEL System (AtCor, Itasca, IL) to analyze systemic vascular parameters like CBP and PWV.ResultsThe study included 296 healthy participants with a mean age of 39.2 ± 6.7 years, and 152 subjects (51.3%) were female. Female participants were found to have higher DCP VD and FAZ area values. Age showed a negative correlation with SCP and DCP VDs. PWV showed a negative correlation with parafoveal DCP VDs, but no correlation was observed between macular VDs and aortic diastolic and systolic pressures.ConclusionIn conclusion, age was found to have a negative impact on macular SCP and DCP VDs. In addition, higher arterial stiffness was found to correlate with a lower parafoveal DCP VD value. These findings suggest macular OCTA parameters may be used as early markers of systemic arterial disease.

A finite element approach to the Keller–Segel Chemotaxis system with impact of nonlocal diffusion

This paper presents the investigation of a boundedness solution for a Keller–Segel chemotaxis (KSC) system with nonlocal diffusion. In order to achieve boundedness, we derive the necessary and sufficient condition based on the assumption of ensuring a unique classical global bounded solution for the proposed KSC system. In this work, the proposed system’s boundedness condition is determined based on three particular situations: when χ<χ∗, χ<κ, and when χ=κ. Finally, the effectiveness of the nonlinear and nonlocal diffusion terms in the KSC system is demonstrated through numerical simulations under consideration of the values of system parameters. From the simulation results, we can confirm the effectiveness of the proposed method.

Light-Powered Self-Translation of an Asymmetric Friction Slider Using a Liquid Crystal Elastomer String Oscillator

In recent years, there have been many studies focused on improving the performance of active materials; however, applying these materials to active machines still presents significant challenges. In this study, we introduce a light-powered self-translation system for an asymmetric friction slider using a liquid crystal elastomer (LCE) string oscillator. The self-translation system was composed of a hollow slide, two LCE fibers, and a mass ball. Through the evolution of photothermal-induced contraction, we derived the governing equations for the system. Numerical simulations revealed two distinct motion modes: the static mode and the self-translation mode. As the mass ball moved, the LCE fibers alternated between illuminated and non-illuminated states, allowing them to effectively harvest light energy to compensate for the energy dissipation within the system. Unlike traditional self-oscillating systems that oscillate around a fixed position, the asymmetric friction enabled the slider to advance continuously through the oscillator’s symmetric self-sustained oscillation. Furthermore, we explored the critical conditions necessary for initiating self-translation as well as key system parameters that influence the frequency and amplitude of the oscillator and average speed of the slider. This self-translation system, with its simple design and ease of control, holds promising potential for applications in various fields including soft robotics, energy harvesting, and active machinery.

Comparison of water surface temperature retrieval methods from Landsat 9 satellite data

Abstract. Water surface temperature (WST) is a crucial parameter in aquatic systems, influencing both water quality and hydrodynamic conditions of these systems. Landsat 9, the latest satellite in the Landsat program, offers a unique opportunity for retrieving Earth's surface temperature data. Despite numerous efforts to develop methods for retrieving surface temperature from remote sensing data, there have been relatively few studies comparing the performance of these methods. The main objective of this study was to evaluate and compare the effectiveness of various methods for estimating WST in a reservoir on Argentina using thermal images from the new Landsat 9 satellite. WST retrievals were obtained from Landsat Collection 2 (C2), Level 2 products, as well as from the Single-Channel (SC) method and a Split-Window (SW) algorithm applied to Landsat C2, Level 1 images. The comparative analysis showed that, although all three methods performed similarly, the Split-Window method proved to be the most effective for estimating WST in the Río Tercero reservoir (R2 = 0.99, RMSE = 0.77 °C). Finally, this method was used to produce detailed WST distribution maps for the studied reservoir.

ANALYSIS OF PROCESSES IN CONVERTER WITH TWENTY-FIVE-ZONE VOLTAGE REGULATION AND ACTIVE-INDUCTIVE LOAD

Analysis of the electromagnetic processes is organized beside this article in electric circuit with semiconductor commutator. Mathematical model is created for analysis electro-magnetic processes in semiconductor converter with width pulsed regulation of the output voltage. The broughted graphs, which reflect the electromagnetic processes in electric circuit. Method much parametric functions was used when performing calculation. The mathematical model of the converter is created for fifteen zoned regulations of the output voltage. Article is devoted to the development of a method of multi-parametric modulating functions by means of working out of new mathematical models and definition of functions and the algorithmic equations for the analysis on sub-system components of electromagnetic processes in electric circuits of variable structure with sinusoidal, direct and pulsing voltage. Introduction of functions with discrete parameters in the algorithmic equations for analysis of processes in circuits with semiconductor commutators simplifies modeling on subsystem components. The mathematical model of steady-state processes and transients in electric circuits of semiconductor converters of modulation type with multi-channel zonal use of phase and line voltages of a three-phase network of power supplies is developed. The mathematical model of electric circuits of thyristor shapers of electro-discharge pulses for the analysis and the matching of capacitors charging modes with decrease several times of electric resistance of technological load is also created. The obtained results have a great value for development theoretical electrical engineering in a direction of simplification of calculations of electromagnetic processes in electric circuits with semi-conductor converters of the electric power. The Electromagnetic processes in electric circuit under width-pulse regulation possible to analyse with use the algorithmic equations multivariable function, which argument are a system parameters semiconductor commutator, signal of control, phases to network of the power supply and time. Introduction multivariable function with discrete parameter in algorithmic equations of the analysis formed and connecting processes in electric circuit of the variable structure allows to reflect change of this structure under system components, simplifying modeling and analysis of such processes to account of the generalization of the got equations. Except specified correlations and diagrams designed model allows to analyse forms of the output voltages and current of the separate power modules.

CSTR parameter identification and PID control optimization based on improved swarm intelligence algorithm

Abstract Aiming at the problems of strong coupling and large hysteresis that exist in the production process of a typical thermal object continuous stirred reactor (CSTR), which make it difficult to recognize the system model parameters and control the temperature, an improved firefly algorithm is proposed to recognize the system parameters, and its recognition accuracy is higher than that of the original firefly algorithm; and an improved sparrow search algorithm (BCGSSA) is used to control the temperature of the CSTR system by combining the BCGSSA algorithm with PID control, which significantly improves the dynamic performance of the CSTR system. Then an improved sparrow search algorithm (BCGSSA) is combined with PID control to control the temperature of the CSTR system, which significantly improves the dynamic performance of the CSTR, and the improved algorithm (BCGSSA) has good control accuracy and robustness.&amp;#xD;

CONTROL DESIGN FOR A MULTIDIMENSIONAL SYSTEM OF ORDINARY DIFFERENTIAL EQUATIONS WITH RELAY HYSTERESIS AND PERTURBATION

A multidimensional controllable system with a constant matrix, a significant nonlinearity of the twoposition relay type with hysteresis as a control and a continuous periodic perturbation function is considered. The system matrix has simple, real, non-zero eigenvalues, among which one can be positive. Conditions for the system parameters, including the nonlinearity ones, are established under which there is a single two-point oscillatory periodic solution with a period comparable to the period of the perturbation function in the case of a special type of the feedback vector. The asymptotic stability of the solution has been proven using the phase plane method. The results obtained are illustrated by examples for three-dimensional systems.

SOLUTION OF THE SPECTRUM ALLOCATION PROBLEM FOR A LINEAR CONTROL SYSTEM WITH CLOSED FEEDBACK

The method for constructing a feedback matrix to solve the problem spectrum allocation (spectrum control, pole assignment) for linear dynamic system is given. A new proof of the well-known theorem about the connection between the complete controllability of a dynamic system with existence of the feedback matrix is formed in the process of construction by the cascade decomposition method. The entire set of arbitrary elements that influence the non-uniqueness of the matrix is identified. Examples of constructing a feedback matrix in the case of a real spectrum and in the presence of complex conjugate eigenvalues, as well as for the case of multiple eigenvalues, are given. The stability of the specified spectrum under small perturbations of the system parameters with a fixed feedback matrix is studied.

The Structural Design and Analysis of the Multi Nozzle Relay Air-Jet Inserting System by Profile Reed Guiding for 3D Weaving Machine

Introduction: Based on the literature, this article designs a parameterized simulation model of a multi-layer jet weft insertion system by profiles reed guidance for a 3D loom on the PTC Creo9.0 platform, including the main supersonic nozzle, supersonic auxiliary nozzle (relay nozzle), and multi-slot profiles reed components. Method: Based on the existing basic theory, experimental results, and empirical data of turbulent jet, the parameters of the multi-layer jet weft insertion system, as well as the structural parameters and the relative positions of the main, auxiliary nozzle and profile reed components, such as the center distance of each layer's main nozzle, auxiliary nozzle spacing, auxiliary nozzle installation angle, spray direction angle, and spray angle, have been determined preliminarily. Result: Further, the basic flow field parameters, such as the supply pressure of the main and auxiliary nozzles and the shape of multi-layer profile reeds, have been determined optimally on the Virtual Prototype Collaborative Simulation Platform (PTC Creo9.0/ANSYS Workbench/Fluent 2024R1), and the rationality of the structural design also been verified; on the premise of ensuring that the airflow velocity of each layer's profiles groove meets the requirements of weft insertion, the design and simulation calculation is repeatedly modified, and the optimal structural design parameters of the multi-layer weft insertion system and nozzle is finally determined. Conclusion: To explore the feasibility of multi-layer jet weft insertion, the design of threedimensional multi-layer jet weft insertion looms has laid a theoretical foundation, laying a good foundation for the emergence and industrial manufacturing of three-dimensional multi-layer jet weft insertion looms, and providing an important reference for the innovative design of threedimensional multi-layer water jet weft insertion looms.

Mathematical model of quality control assessment of the technical condition radio electronic equipment

The article examines the issue of monitoring the technical condition of special-purpose radio-electronic equipment under the influence of external factors. The main attention is paid to the formalization of the control process through the construction of a mathematical model that describes the dependence of the initial parameters of the control system on internal and external influences. The existing control methods are analyzed, which reflect the difficulties of selecting control points in modern integrated circuits. The necessity of introducing new, more flexible and adaptive solutions in solving the problems of technical diagnostics is shown. The work proposes an improved mathematical model for monitoring the technical condition of radio-electronic equipment, which allows more accurate assessment of the functional state of the control object in real time. The control process is described in the model through probabilities of changing the state of a generalized indicator that ensures the accuracy of the control system. This approach to quality control of the functional state of the object based on the construction of stochastic graphs allows to estimate the probability of error and accuracy during the control of the technical condition. The results of the research can be applied to the effective maintenance of radio-electronic equipment, as well as improving indicators of diagnosing the technical condition and predicting possible failures of the control object.

Особенности системы гемостаза при истинной полицитемии у детей

Patients with polycythemia vera (PV) are at an increased risk for thrombosis. Abnormalities in coagulation parameters and global hemostasis tests can help with hypercoagulation recognition in PV. The purpose of this research was to analyze the features of changes in laboratory parameters of the hemostasis system in pediatric patients with PV. Materials and methods used: a single-center retrospective cohort study of clinical records of 32 (11 (35%) girls/21 (65%) boys aged 11.5 [0.8; 17.5] y/o) pediatric (all under the age of 18 y/o) PV patients who were admitted at the National Scientific and Practical Center for Pediatric Hematology, Oncology and Immunology named after Dmitry Rogachev (Moscow, Russia) in Jan. 2012-June 2024 was conducted. Laboratory parameters were determined prior to the beginning of the antiplatelet and cytoreductive therapy. Results: in 20 (62.5%) and 4 (12.5%) patients, mutations in the JAK2V617F and JAK2 ex 12 genes were detected, respectively, the remaining 8 (25%) children were JAK2-negative. In total, there were 8 (72%) JAK2-positive girls and 15 (71%) boys; gender did not statistically significantly affect the presence of a driver mutation (p=0.939). Both the median and the mean values of the main parameters of the blood coagulation system were within the reference values. The thromboelastography parameters did not deviate from the reference values for the parameters. According to the results of the thrombodynamics study, the average value of the initial clot growth rate among all patients was increased and amounted to 58.3±5.07 μm/min, the steady-state velocity also increased among all patients to 29.5±4.3 μm/min, the median and the mean values of the remaining parameters were within the reference intervals. Conclusion: the parameters of standard coagulogram and thromboelastography tests in pediatric PV patients had no deviations. The average values of thrombodynamics (initial and steady-state clot growth rate) were increased, which potentially indicates the hypercoagulation.

Cardiorespiratory system of massage therapists when performing a dosed massage procedure

The article tells about the presentation of a number of studies on the effect of massage procedures on the physiological, biochemical and psychological status of a person, while work on evaluating the functional indicators of massage therapists during the procedure is rare. The study aims to determine the functional state of the cardiorespiratory system (CRS) of massage specialists in the dynamics of performing a 30-minute back massage session. The object of the study was 10 male massage therapists (age 36.0 (29.0;42.0); BMI 24.7(23.3;31.3). The study consisted in performing a classical back massage procedure for 30 minutes according to a generally accepted technique using six massage techniques. To determine the functional state during the work of specialists, an ergospirometric system and measurement of blood pressure (BP) by the Korotkiy method were used. During the massage procedure, specialists noted an increase in metabolic parameters, oxygen consumption (OC), respiratory coefficient (RC) and energy consumption, as well as blood pressure by the 30th minute of the procedure. When performing a 30-minute back massage, massage specialists significantly mobilize the links of the cardiorespiratory system. At the end of the procedure, there is an increase in blood pressure. However, the maximum increase in the parameters of the cardiorespiratory system occurs when performing a shock vibration reception. Limitations. Due to the small sample of the group, it is not possible to statistically reliably assess the significance of changes in some indicators. Ethics. The protocol of the experiment corresponded to the Helsinki Declaration. The study was developed and conducted in accordance with the methodological guidelines of the Local Scientific Research Committee on Bioethics of the Institute of Physiology of the Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences.