Table of Contents


    • A study of convergence of ξ approximations transform by region depended given as determined by () Functions on entire complex plane

      pg(s) 104-105

      In this study, the convergence behavior of the ξ approximants transform given as determined by () functions for the exponential operators is investigated on the entire complex plain. An algorithm is developed to observe how to transform a initial region on the complex plane defined by ξ approximants.

    • Modeling of аgent-based cyber-physical systems using goal-oriented approach

      pg(s) 106-109

      Cyber-physical systems (CPS) integrate computing, networking and physical dynamics and are characterized by a high degree of heterogeneity and parallelism, with high dimensionality and complexity, including a variety of decision-making capabilities and control logic. Modeling and simulation of cyber-physical systems are considered important stages in the design, development and operation of CPS and their components. The main aim of the paper is to describe and analyze the evolution of agent based approach in the field of CPS and to define the basic requirements to the agent based systems regarding CPS. Based on O-MaSE methodology a software process model for agent based development of CPS is proposed. The approach includes the creation of 10 models reflecting various aspects and functionality of the CPS. The suggested approach is analyzed in terms of meeting the basic requirements for agent-based systems, imposed by the peculiarities of cyber-physical systems and fundamental requirements for their introducing, such as flexibility/changeability, reliability, reconfigurability, adaptability/agility and dependability.


    • Simulation of the main components of a nuclear reactor under load, made of ultrafinegrained steel AISI-321 in the normal and irradiated state

      pg(s) 110-113

      The creation and calculation of computer models of various products under load with the properties of UFG materials in the normal and irradiated state was performed. To model the UFG properties of non-irradiated AISI-321 steel, hardening curves were constructed based on the Hall-Petch equation for the base state of the material at a grain size of 1500 nm and for two UFG states (with grain sizes of 700 and 200 nm). To simulate the properties of irradiated AISI-321 steel, plastometric tests were performed using uniaxial compression of cylindrical samples at constant values of the strain rate of 1 s-1 and the temperature of 20°C on the “Gleeble 3800” plastometric unit. Fast neutron fluence with the following values was selected as a variable parameter: 0.5∙1018 n/cm2, 1∙1018 n/cm2, 0.5∙1019 n/cm2, 1∙1019 n/cm2. The maximum operating pressure of 340 MPa was used as a static load. The simulation results showed that for both parts, the use of the material in the UFG state is the most appropriate solution.

    • Mathematical modeling of automated production systems

      pg(s) 114-120

      The paper theoretically substantiates and practically implements mathematical methods of modeling production systems, proves the adequacy of mathematical models and optimization methods, as well as selected rational optimization methods and created software that implements the selected methods in practice. The analysis of methods of modeling and optimization of production technological systems is performed, the most effective methods of solving these problems for discrete production are selected. The main provisions of infinite-valued logic and ordinal determinants, on which the structural-logical approach to the study of complex systems, which include production systems in instrument making, are considered.

    • Atmospheric Observation and Radio Signal Measurements over the Black Sea Region for Assessment of Tropospheric Radio Propagation and Potential Radio Interferences

      pg(s) 121-124

      Due to various interferences arising from the tropospheric propagation of radio waves over big water basins, it is necessary to study in detail the mechanisms of propagation and to improve the existing models for determining propagation factor or path loss profiles at different frequencies, especially in UHF bands, caused by the growing interest of mobile communications and especially 5G technologies. To get enough information about radio wave propagation over the Black sea area, the state of atmosphere above points of interest is studied in detail and the results are compared with real measured radio signals distributed between those points. The results are compared with basic theoretical computed models. The results showed more than 10 dB and from 6 to10 dB difference respectively for VHF and UHF between measurement and computed with Three way path loss model EMF levels for the favorable cases which might be due to additional ray in the receiver. A clear relationship between received EMF levels and wind speed but in combination with different abnormal tropospheric environments and relationship between absolute value of modified refractivity and the levels of received signals for the surveyed regions


    • Injury prevention during childbirth: The model of obstetrician

      pg(s) 125-127

      During childbirth, a technique called manual perineal protection (MPP) is often used to prevent injuries of relevant tissues. The obstetrician uses his (or her) hand to apply certain forces at the perineum in order to decrease its excessive loading during child delivery. Amount of applied forces as well as the correct posture of the obstetrician during the MPP technique are based so far on the experiences and approach of the obstetrician himself (or herself). In order to assess the role of obstetrician and in order to optimize the MPP technique, mathematical models may be of use. This work presents a combination of both experimental measurement and mathematical modeling. In the experimental part, a unique device is developed to measure forces applied by obstetrician during real child delivery. In the modeling part, the obstetrician is represented with an active musculoskeletal human body model in an AnyBody Modeling System software. Providing forces and muscle activities of the model may lead to the assessment and optimization of the MPP technique.

    • Injury prevention during childbirth: A model of pelvic floor

      pg(s) 128-130

      During vaginal delivery women suffer with several kinds of injuries which may negatively influence their quality of life. Different techniques are used for perineal protection during the second stage of the delivery. A method called manual perineal protection (MPP) is used to decrease the risk of severe perineal trauma. In order to quantify this method a special measuring glove was designed and forces generated by the obstetricians during real deliveries were measured. Measured forces were then used in computer simulation of the MPP method. The forces were applied on a previously developed FEM model of the pelvic floor during simulation of the vaginal delivery. The stress distribution in the perineal area was monitored. Reactions of perineal tissues were evaluated. The simulations of childbirth with and without MPP were compared