Characteristics Of System Research Articles

Dynamic characteristics analysis of gear tooth modification in a three-stage gear system

Gears serve as vital elements in high-efficiency mechanical transmissions, playing a pivotal role in vehicles. Employing gear modification has the capacity to significantly enhance the dynamic properties of the Planetary Gear Transmission (PGT) systems. In this study, the investigation has been directed toward a three-stage PGT model system with a comprehensive consideration of various vibration-related factors that affect the dynamic behavior of the system. These factors are encompassed by Time Varying Mesh Stiffness (TVMS), torsion and bending forces experienced by connecting shafts, dynamic Transmission Error (TE), impact of gear meshing eccentric load forces, inherent flexibility in the supporting shaft structure, and influence of torque and power fluctuations originating from a multi-cylinder engine. The estimation of TVMS is carried out for both external-external and external-internal teeth meshing pairs, utilizing the Potential Energy Method (PEM). Subsequently, this study employs the lumped parameter method to establish a model with a specific objective of investigating the lateral-torsional-coupling behavior within adopted PGT model system. The lateral vibration displacement characteristics of the PGT model system is deeply analyzed, revealing the influence of speed on lateral vibration and displacement frequency domain characteristics through a 3D waterfall diagram. Furthermore, a Tooth Profile Modification (TPM) method is applied utilizing two distinct parameters namely [Formula: see text] TPM parameter and [Formula: see text] TPM parameter. The objective is to mitigate vibrations and evaluate the performance of the adopted PGT model after employing each TPM parameter through both TVMS and Root Mean Square (RMS).

Magnetic-Control Variable Stiffness and Damping Tail Support for a Wind-Tunnel Aircraft Model

To suppress random vibration of aircraft models during wind tunnel tests, a novel magnetorheological elastomer (MRE)-based device with variable stiffness and variable damping (VSVD) is proposed, which is installed on the tail support system. Firstly, the dynamic characteristics of the tail support system are established using finite element model simulation to obtain the vibration mode and stress distribution. Next, the vibration reduction mechanism of the MRE-based tail support system is analyzed by solving a finite element model. Then, the magnetic-controlled VSVD device with an annular sandwich structure is proposed, and the decisive rheology material and structural parameters in relation to the tail support system’s dynamics are determined. Subsequently, the magnetically generated element with multicoils is designed to guarantee a large enough magnetic field, and the optimal structure parameters are obtained. Finally, random wind flow experiments in the wind tunnel and frequency sweep tests in the ground laboratory for the tail support system equipped on the VSVD device are conducted to verify the effectiveness of the proposed device, respectively. The results under 15–200 Hz random excitation indicate the root mean square of acceleration at the centroid of the aircraft model with the VSVD device can be decreased by 46.8% compared to the system without the VSVD device.

Study on Dynamic Characteristics of Vibration System with Two Degrees of Freedom and Multiple Rigid Constraints

A dynamic model of a vibration system with two degrees of freedom and multiple rigid constraints is constructed, the dynamics constraints of the segmented smooth vibration system under the multi-body impact coupling condition are given. Based on the cell mapping principle, a two-parameter co-simulation is carried out with two important parameters of excitation frequency and constraint gap as control variables. The model types and distribution rules of the periodic motion of the system response on the [Formula: see text]-whole two-parameter plane are obtained. The correlation between the dynamic response of the system and the model parameters is analyzed, and the evolution and bifurcation characteristics of fundamental periodic vibrations in the low-frequency small-gap parameter domain of the two-degree-of-freedom multi-rigid constrained vibration system are discussed. The diversity and regularity of subharmonic shock vibrations in the translational domain of the lingual domain are found.

Nonlinear Dynamic Analysis of FG Fluid Conveying Micropipes with Initial Imperfections

This paper investigates the nonlinear dynamics of FG-FCMPs with initial imperfections. Based on the MCST, the nonlinear equations of motion and the corresponding boundary conditions are established by applying Hamilton’s principle, the Euler–Bernoulli beam theory, and von-Kármán geometric nonlinearity. To describe the initial geometric imperfection of the FG-FCMP, the first-order vibrational mode is employed. Subsequently, in cases of primary parametric resonance, 1:2 subharmonic resonance for the first-order mode, as well as primary resonance for the second-order mode, Galerkin’s method, and the multiple scale method are utilized to analyze the amplitude–frequency responses of the imperfect FG-FCMP. The numerical simulations test the influence of flow velocity, micro-scale parameter, geometrical imperfections, and external loads on the nonlinear characteristics of a coupled system with two DOFs. It is found that, as the increase of flow velocity, micro-scale effect, and external load, the amplitude of the first two modes can be increased. The hardening characteristics are converted into the softening characteristics due to the imperfect effect. Furthermore, numerical results provide a more comprehensive understanding of the nonlinear dynamics of FCMPs for both periodic and chaotic motions.

Optoelectronic Torque Measurement System Based on SAPSO-RBF Algorithm.

The torque is a significant indicator reflecting the comprehensive operational characteristics of a power system. Thus, accurate torque measurement plays a pivotal role in ensuring the safety and stability of the system. However, conventional torque measurement systems predominantly rely on strain gauges adhered to the shaft, often leading to reduced accuracy, poor repeatability, and non-traceability due to the influence of strain gauge adhesion. To tackle the challenge, this paper introduces a photoelectric torque measurement system. Quadrants of photoelectric sensors are employed to capture minute deformations induced by torque on the rotational axis, converting them into measurable voltage. Subsequently, the system employs the radial basis function neural network optimized by simulated annealing combined with particle swarm algorithm (SAPSO-RBF) to establish a correlation between measured torque values and standard references, thereby calibrating the measured values. Experimental results affirm the system's capability to accurately determine torque measurements and execute calibration, minimizing measurement errors to 0.92%.

A virtual gym in your pocket: the influence of augmented reality exercise app characteristics on user’s continuance intention

In recent years, with the development of augmented reality (AR) technology and the prevalence of COVID-19, augmented reality exercise applications (AREAs) have entered people’s lives and changed people’s exercise ways. However, there is still little research on how AREAs affect users’ continuance intention, which limits our deeper understanding of the further use of AREAs by users for the potential benefits they provide. This study investigates the role of AREAs by proposing the original proposition of AREAs characteristic classification based on previous AR literature and dividing their characteristics into two categories: service and system characteristics. Through an online empirical study, 398 valid questionnaires were collected to test the hypotheses using the structural equation model. The results showed that hedonic and utilitarian value and presence are vital inner states which mediate the influence of service and system characteristics on user’s satisfaction and continuance intention. The results further show that only hedonic value is found to have a positive and significant relationship with continuance intention. This study contributes to the literature in the AR field by examining how different AR application characteristics affect user continuance intention in the context of sports and fitness. It also suggests that practitioners should identify the impact of different characteristics on user value and focus on the hedonic aspects of the application.

Influence of Ventilation Air Supply into the Space Between Two Glass Units on the Energy Characteristics of this Transparent System

By the method of numerical simulation, the heat transfer from the room to the environment through a system of two double-chamber windows, into the gap between which ventilation air from the room supplies, is being researched. Distributions of air velocity and temperature in the chambers of double-chamber windows and in the gap between double-chamber windows are determined. The influence of the flow of ventilation air entering the space between the double-chamber windows on the amount of heat transferred from the room to the space between windows through the inner window and the amount of heat removed from the gap to the environment through the external double-chamber window is investigated. The energy advantages of the method of removing ventilation air through the gap between double-chamber windows over the method of direct removal of ventilation air from the room to the environment are determined.

A new performance‐based seismic design method using endurance time analysis for linked column frame system and a comparison of structural systems and seismic analysis methods

SummaryThis paper presents a new performance‐based seismic design method for the design of repairable linked column frame (LCF) and linked column system (LCS). Currently, the biggest problem of these systems is the lack of a simple and practical design method that leads to the design of optimal models with sufficient seismic capacity. The interaction of the primary and secondary systems, changing the lateral load pattern during an earthquake, and the implementation of the target performance objectives have complicated the design of these systems. The evaluations carried out in this research show that the rotation of link beams must be controlled in the design. Therefore, the ultimate plastic rotation of links is determined to be 0.01 rad for the seismic intensity of design base earthquake and 0.015 rad for maximum considered earthquake. The results show that the models designed using the presented method are optimal, have sufficient seismic capacity, and achieve the target performance objectives. In addition, although previous researches have shown that these systems have a suitable seismic behavior, their seismic behavior have not been compared with other structural systems. Comparing can show the behavioral characteristics of a new structural system; hence, the elastic and plastic behavior of the LCF and LCS models have been compared with other common steel structural systems using all analysis methods. Moreover, in the presented method for the design of LCF and LCS systems, nonlinear time history analysis using the endurance time method (ETM) is used, and due to the newness of the endurance time method, its results are compared with the median results of nonlinear time history analysis at different seismic hazard levels and incremental dynamic analysis (IDA), in 45 samples. The results show that the endurance time analysis is a reasonable and efficient method, and in this comparison, the difference between the results of ETM and IDA methods is 6% on average.

Pattern-Moving-Modelling and Analysis Based on Clustered Generalized Cell Mapping for a Class of Complex Systems

Considering a class of complex nonlinear systems whose dynamics are mostly governed by statistical regulations, the pattern-moving theory was developed to characterise such systems and successfully estimate the outputs or states. However, since the pattern class variable is not computable directly, this study establishes a clustered generalized cell mapping (C-GCM) to reveal system characteristics. C-GCM is a two-stage approach consisting of a pattern-moving-based description and analysis method. First, a density algorithm, named density-based spatial clustering of applications with noise (DBSCAN), is designed to obtain cell space Ω and the corresponding classification guidelines; this algorithm is initiated after the initial pre-image cells, and the total number of entity cells amounts to Ns. Then, the GCM provides several image cells based on a cell mapping function that refers to the multivariate ARMAX model. The global dynamic analysis employing both searching and storing algorithms depend on the attractor, domain of attraction, and periodic cell groups. At last, simulation results of two examples emphasise the practicality as well as efficacy of the technique suggested. The chief aim of this study was to offer a new perspective for a class of complex systems that could inspire research into nonmechanistic principles modelling and application to nonlinear systems.

Numerical simulation and experimental verification of solar PVT coupled PEM electrolyzer system for hydrogen production

Hydrogen production by electrolysis of water is the key to the future of hydrogen fuel production. This study proposes a hydrogen production system based on the thermoelectric demand for proton exchange membrane electrolyzers (PEMEs) and the characteristics of the thermoelectric output of photovoltaic (PV) thermal (PVT) systems. The proposed system combines PVT and PEME to realize thermoelectric hydrogen–oxygen multiproduction and establishes and validates the thermoelectric coupled numerical model used for the prediction of the operating characteristics of the PVT-PEME system. Furthermore, it investigates and compares the irradiation intensity, ambient temperature, and inlet flow rate of the PVT-PEME and PV-PEME systems, and estimates the operating characteristics of the PVT-PEME system in different climates. The results show that the electrolyzer energy efficiency tends to increase and then decrease with increasing irradiation intensity; the PVT-PEME efficiency increases with increasing ambient temperature; and the PV-PEME efficiency decreases with increasing ambient temperature. Moreover, the efficiency of the electrolyzer decreases with an increase in the inlet flow rate, but the PVT-PEME efficiency increases. The high temperature inhibits the performance of PV modules, which is promoted in PEME after heat exchange in the PVT system, improving the operating efficiency. In addition, an evaluation of the actual operating characteristics of the PVT-PEME hydrogen production system in different climates indicates that the system operated for shorter and less efficient times when operating at cold and low irradiation intensities.

Effect of Impellers on the Cooling Performance of a Radial Pre-Swirl System in Gas Turbine Engines

Impellers are utilized to increase pressure to ensure that a radial pre-swirl system can provide sufficient cooling airflow to the turbine blades. In the open literature, the pressurization mechanism of the impellers was investigated. However, the effect of impellers on the cooling performance of the radial pre-swirl system was not clear. To solve the aforementioned problem, tests were carried out to assess the temperature drop in a radial pre-swirl system with various impeller configurations (impeller lengths l/b ranging from 0 to 0.333). Furthermore, numerical simulations were used to investigate the flow and heat transfer characteristics of the radial pre-swirl system at high rotating Reynolds numbers. Theoretical and experimental investigations revealed that the pre-swirl jet and output power generate a significant temperature drop, but the impellers have no obvious effect on the system temperature drop. By increasing the swirl ratio, the impellers reduce the field synergy angle and thus improve convective heat transfer on the turbine disk. In addition, increasing the impeller length can reduce the volume-averaged field synergy angle and improve heat transfer, but the improvement effectiveness decreases as the impeller length increases. Thus, the study concluded that impellers could improve the cooling performance of the radial pre-swirl system by enhancing disk cooling.

Thermal diffusion and microstructural evolution of Cu-Zn binary system under hypergravity

It has long been a common assumption that the stress conditions for materials operating in hypergravity could be simplified to traditional stress conditions. However, such simplification has not been experimentally verified. In this study, we examined the thermal diffusion and microstructural evolution of the Cu-Zn binary system under hypergravity levels of up to 4700 g (g: gravity of Earth, 9.8 m/s2). Our findings revealed distinct differences when compared to the behaviour of the materials under traditional stress. Under hypergravity, we observed an enhancement in interfacial diffusion of atoms up to 3500 g, and this enhancement was suppressed under 4700 g hypergravity. Additionally, a directional effect was observed, where the diffusion layer formed in hypergravity from Cu to Zn direction was thicker than that formed under the opposite direction of hypergravity. Furthermore, the reduction of dislocations in the diffusion layer was observed as the hypergravity increased. The study suggests that the hypergravity-induced centrifugal force (Fg) and buoyancy force (Fb) significantly influence the diffusion characteristics of the Cu-Zn binary system. Fg enhances interfacial contact and promotes interfacial diffusion, while Fb promotes the diffusivity of vacancies, and thereby atoms, contributing to the observed directional effects. These factors ultimately lead to the formation of a biphasic phase and the suppression of precipitation under hypergravity. Additionally, as the hypergravity increases, defects/vacancies reduce, resulting in the suppression of diffusion. Our findings provide valuable insights into the diffusion and microstructural evolution of materials under hypergravity conditions.

Nonlinear vibration control of magnetic bearing system considering positive and negative stiffness

The nonlinear dynamics are studied for an active magnetic bearing (AMB) system under the low-frequency sinusoidal excitation, which can affect the operational stability of a high-speed magnetic bearing. A single-degree-of-freedom nonlinear dynamics model of magnetic bearing was developed with a c-type active magnetic bearing as the research target. The characteristics of the magnetic bearing system show positive and negative stiffness for different feedback gains. The amplitude–frequency response curves of the vibration characteristics of the positive stiffness magnetic bearing system were obtained by using the method of multiple scales. The influence of each parameter on the resonance amplitude and nonlinearity of the magnetic bearing system is understood by analyzing the amplitude–frequency response curve. The bifurcation diagram for the rotor with rotor mass, and control parameters is derived from the numerical simulation of the negative stiffness magnetic bearing system. The parameter intervals that cause single-cycle vibration, double-cycle vibration, and chaotic state of the magnetic bearing rotor are discovered by analyzing the bifurcation diagrams of each parameter. The simulation results show that the magnetic bearing system exhibits complex nonlinear dynamic characteristics when it is a negative stiffness system.

Justification of the Unit Design Diagram for Mowing Agricultural Crops Simultaneously with Their Stuble Chopping

Abstract The two-phase method is quite widespread when harvesting grain crops and forage grasses. For its implementation, farmers prefer harvesting units with a front-mounted header. The main disadvantage of such units is that after their passage in the space between the swaths of mown crops, open soil falls under the direct influence of sunlight. Subsequently, this leads to an intensive loss of its moisture. A harvesting unit has been designed to eliminate this shortcoming, consisting of a tractor with a front harvester and a soil-cultivating machine (disc harrow) mounted at the rear. The latter chops stubble and soil in the space between the swaths of the mowed crop, contributing to soil moisture conservation. In the diagram plan, the tillage machine can have a swivel or fixed conjunction with the tractor in a horizontal plane. A mathematical model of the harvesting unit plane-parallel movement in the horizontal plane has been designed to choose these conjunctions better. In the study, it is used to analyze the corresponding amplitude (AFC) and phase (PFC) frequency characteristics of a dynamic system when it is working out a control action in the form of the sighting point transverse shift. As a mathematical modeling result, it was found that the fixed conjunction of a tillage machine with a tractor is preferable. In this case, the natural AFC practically approaches the perfect one for servo dynamical systems. The correlation degree between the tractor‘s steered wheels‘ rotation and heading angles increases by almost 37%. As a result, this leads to a significant decrease in this parameter variance fluctuations, which contributes to an increase in the harvesting unit controllability movement as a whole.

MHD free convective flow and entropy production of glycerin in a square domain with Joule heating and internal heat generation

This study inspects MHD free convective flow and entropy production inside a square domain (e.g., a nuclear reactor thermal cooling system) with Joule heating and internal heat generation. The left edge of the domain is set to a higher temperature than the right edge, and the top and bottom edges are insulated. The domain is filled with a heat-generating and electrically conducting fluid (glycerin) with fixed thermo-physical properties. This study has practical significance in many engineering applications, including nuclear reactor cooling systems, cooling electronics, designing solar thermal collectors, designing heat exchangers, etc. The primary objective of this study is to enhance heat transfer by examining optimal system characteristics. The Navier-Stokes and heat energy equations, which govern heat and fluid flow in the domain, are solved via the Galerkin finite element technique. Numerical simulation is performed over specific ranges of Rayleigh number (103 ≤ Ra ≤ 106), Joule heating parameter (0 ≤ J ≤ 7.31 × 10−9), Hartmann number (0 ≤ Ha ≤ 36.98), and volumetric heat generation coefficient (0 ≤ Δ ≤ 2) under laminar flow consideration. The parametric conditions for achieving the desired thermal performance can be controlled by determining the mean Nusselt number of the heated edge. Notably, heat transfer enhancement ensues with the simultaneous increment of Ra and Ha at a fixed Joule heating parameter. On the other hand, introducing internal heat generation reduces thermal performance inside the system, which has also been observed in terms of mean fluid temperature, total entropy production, and average Bejan number.

The role of mesolevel characteristics of the health care system and socioeconomic factors on health care use – results of a scoping review

BackgroundBesides macrolevel characteristics of a health care system, mesolevel access characteristics can exert influence on socioeconomic inequalities in healthcare use. These reflect access to healthcare, which is shaped on a smaller scale than the national level, by the institutions and establishments of a health system that individuals interact with on a regular basis. This scoping review maps the existing evidence about the influence of mesolevel access characteristics and socioeconomic position on healthcare use. Furthermore, it summarizes the evidence on the interaction between mesolevel access characteristics and socioeconomic inequalities in healthcare use.MethodsWe used the databases MEDLINE (PubMed), Web of Science, Scopus, and PsycINFO and followed the ‘Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols extension for scoping reviews (PRISMA-ScR)’ recommendations. The included quantitative studies used a measure of socioeconomic position, a mesolevel access characteristic, and a measure of individual healthcare utilisation. Studies published between 2000 and 2020 in high income countries were considered.ResultsOf the 9501 potentially eligible manuscripts, 158 studies were included after a two-stage screening process. The included studies contained a wide spectrum of outcomes and were thus summarised to the overarching categories: use of preventive services, use of curative services, and potentially avoidable service use. Exemplary outcomes were screening uptake, physician visits and avoidable hospitalisations. Access variables included healthcare system characteristics such as physician density or distance to physician. The effects of socioeconomic position on healthcare use as well as of mesolevel access characteristics were investigated by most studies. The results show that socioeconomic and access factors play a crucial role in healthcare use. However, the interaction between socioeconomic position and mesolevel access characteristics is addressed in only few studies.ConclusionsSocioeconomic position and mesolevel access characteristics are important when examining variation in healthcare use. Additionally, studies provide initial evidence that moderation effects exist between the two factors, although research on this topic is sparse. Further research is needed to investigate whether adapting access characteristics at the mesolevel can reduce socioeconomic inequity in health care use.

Investigating factors affecting the evaluation of teachers’ medical universities from the students’ point of view: a systematic review

BackgroundFaculty evaluation is essential as a principle in educational organizations because it helps measure the quantity and quality of education in universities and educational institutions. There are various ambiguities regarding the desirable and deserving characteristics of a good teacher. Therefore, this study was conducted with the aim of investigating factors affecting the evaluation of teachers’ medical universities from the perspective of students.MethodsA systematic review study was conducted by searching for studies in both Persian and English languages from 2014 to 2022 in the following databases: Pubmed, Web of Science, Scopus, Cochrane, Google Scholar, and ScienceDirect, Magiran, SID, Iran Doc using keywords including Evaluation, Assessment, Estimate, Appraisement, Appraisal, Faculty Member, Professor, University, and College, as well as their MeSH equivalents, using “AND” and “OR” operators. The results of the articles about investigating factors affecting the evaluation of teachers’ medical universities from the perspective of students were reviewed, summarized, and reported.ResultsIn the initial search, 3949 articles were found, and after evaluation, finally 21 articles were included in the systematic review. Based on the findings, investigating factors affecting the evaluation of teachers’ medical universities from the perspective of 130,187 students can be categorized into 6 dimensions and 53 components. These dimensions include individual and professional characteristics of the educational system, attitude within the educational system, educational programs and guides, teaching methodology, internal coherence of educational resources, and evaluation system information.ConclusionThe results of the articles about investigating factors affecting the evaluation of teachers’ medical universities from the perspective of students were reviewed, summarized, and reported. It is necessary to pay attention to the factors affecting the evaluation of teachers in the recruitment of faculty members. Additionally, by holding practical training workshops with consideration of various dimensions that have an impact on faculty evaluation and student learning, it is possible to enhance the expertise of faculty members.

Tunable plasmonic superchiral light for ultrasensitive detection of chiral molecules.

The accurate detection, classification, and separation of chiral molecules are pivotal for advancing pharmaceutical and biomolecular innovations. Engineered chiral light presents a promising avenue to enhance the interaction between light and matter, offering a noninvasive, high-resolution, and cost-effective method for distinguishing enantiomers. Here, we present a nanostructured platform for surface-enhanced infrared absorption-induced vibrational circular dichroism (VCD) based on an achiral plasmonic system. This platform enables precise measurement, differentiation, and quantification of enantiomeric mixtures, including concentration and enantiomeric excess determination. Our experimental results exhibit a 13 orders of magnitude higher detection sensitivity for chiral enantiomers compared to conventional VCD spectroscopic techniques, accounting for respective path lengths and concentrations. The tunable spectral characteristics of this achiral plasmonic system facilitate the detection of a diverse range of chiral compounds. The platform's simplicity, tunability, and exceptional sensitivity holds remarkable potential for enantiomer classification in drug design, pharmaceuticals, and biological applications.

Effect of turbine's torque and speed variation on hydraulic vibration analysis during transient processes

AbstractWith the rapid development of large‐capacity hydraulic turbines and pumped‐storage power stations, hydraulic vibration analysis attracts increasing attention nowadays. To explore the influence of torque and speed variation on hydraulic vibration characteristics during transient processes and ensure the stability of hydropower stations, an improved analytical formula of turbine impedance involving the torque and speed variation was then derived. The free vibration analysis and forced vibration analysis using the transfer matrix method and the hydraulic impedance method were carried out. According to the numerical simulations, the obtained attenuation factors show differences in magnitude which illustrates that the torque variation and speed variation in transients do affect the damping rate of the vibration. In addition, the results indicated the natural angular frequencies of hydropower system were mainly dependent on the length of water conveyance system and pipe characteristics. It can be inferred form vibration mode shapes that for some specific frequencies, the magnitude of oscillatory pressure head and flow rate along the downstream tail tunnel are influenced by the hydraulic turbine. The correlation between the turbine impedance and guide vane openings tells that the hydraulic impedance is getting smaller as the opening increases. What's more, the corresponding free vibration analysis shows that the absolute value of the damping rate is closely related to the value of the flow rate.

Кардиологический профиль недоношенных новорожденных с массой тела при рождении менее 2500 граммов в раннем детском возрасте

Purpose of the research was to establish the characteristics of the cardiovascular system in premature newborns with a birth weight below 2500 gram in their early childhood. Methods used: the data of 302 children born in 2014-2020 in the Tomsk Oblast Regional Perinatal Center named after I.D. Yevtushenko and the Maternity Hospital No. 4 (both located in Tomsk, Russia) were analyzed. The control group of 76 was formed from healthy full-term newborns. The comparison group of 226 consisted of premature infants with birth weight below 2500 gram with the three subgroups depending on birth weight: low (LBW), very low (VLBW) and extremely low body weight (ELBW). During the follow-up that lasted for up to 3 years after birth an anamnesis, physical examination and fixation of the results of paraclinical studies (ECG, EchoCG) were carried out. Results: the probability of having a cardiac diagnosis among children with ELBW at birth at the time of discharge from the obstetric institution was 7 times higher compared to children with LBW (OR=7.60; [CI 95% 1.6-35.3]); birth weight below 1500 gram was associated with a 7-fold greater likelihood of PDA persistence compared to children with LBW at birth (OR=7.44; [CI 95% 3.34-16.55]); in the comparison group at the different age periods the low EchoCG parameters of heart size were established, while normal values of the left ventricular ejection fraction were noted. Conclusion: children with ELBW at birth differed in their cardiological profile already in their early childhood.