• Solution of the system of equations of energy and mass transfer with account of volumetric heat sources

    pg(s) 108-109

    The paper considers an analytical method for solving systems of equations of conjugate non-stationary heat and mass transfer with account of volumetric negative or positive heat sources (and steam generation aswell). The obtained data can be used to find integral kinetic dependencies of heat and mass exchange processes, analytical formulas for calculating heat and mass transfer coefficients and other derivative quantities necessary for engineering calculations of processes and devices in chemical technology, biotechnology, industrial heat power engineeringand other industries.

  • Mathematical modeling of aluminum alloys

    pg(s) 104-107

    Aluminum alloys are critical in industries such as aerospace and automotive due to their lightweight, strength, and corrosion resistance. Optimizing their properties is challenging and benefits from advanced predictive tools. This paper explores the use of mathematical modeling in understanding and designing aluminum alloys. Techniques like thermodynamic modeling (e.g., CALPHAD), phase transformation kinetics, and mechanical property simulations are reviewed. Computational methods, including finite element analysis and machine learning, are highlighted for their roles in alloy design and manufacturing, such as casting and additive manufacturing. Comparisons between model predictions and experimental results demonstrate accuracy and limitations. Applications in optimizing material properties and improving manufacturing processes are discussed. By accelerating alloy development and enabling tailored properties, mathematical modeling emerges as a transformative tool, advancing aluminum alloy research and driving innovation across industries.

  • Modeling of Shredding Blade for Nonwoven Waste Fabric

    pg(s) 101-103

    In this study, cutter blades were designed to shred nonwoven waste fabrics by being positioned on an existing shaft. In this context, the design was carried out by considering the shear stress and density of the material to be shredded. During the design process, the total deformation conditions on the cutting surface were examined, and the stress concentration regions were identified using the von Mises approach to determine the necessary mechanical properties of the cutter blade. At this stage, the most suitable cutting tool material was selected. To ensure the torque from the motor is evenly distributed to the cutting edges and to meet the requirements of the material to be cut/shredded as well as the targeted machine capacity, various tool geometries were created and designed. In this context, analyses were performed to determine the effect of the selected geometries on the load distribution on the cutting edges, and the optimal tool geometry was decided.

  • Determination Of Physico-Chemical Parameters Of Hydrocarbon Gas Based On Field Data

    pg(s) 98-100

    The fluids that are present in the underground reservoirs of oil and gas, both in the initial conditions and in the exploitation conditions of the reservoir, experience different phase behavior. All these are accompanied by different physico-chemical parameters, the determination of which plays an important role in the hydrodynamic study of the well or the reservoir as a whole. The fluids released from the formation change over time due to the change in the phase state of the fluids, their material and energy balance. In this study, based on the field data obtained during the exploitation of the oil and gas bearing bed, the physico-chemical parameters of the gas were determined based on the correlations derived from the various experimental studies carried out in the world.

  • Analysis and comparison of steam turbines from older and newer power plant

    pg(s) 94-97

    In the presented paper are performed energy and exergy analyses as well as a comparison of two similar steam turbines from conventional power plants. The first turbine is from an older, while the second turbine is from newer steam power plant. The dominant mechanical power producer in an older steam turbine is LPC (which produces mechanical power of almost 66 MW), while in a newer steam turbine the dominant mechanical power producer is IPC which produces power equal to 102.4 MW. Whole older steam turbine has higher energy and exergy loss in comparison to the whole newer steam turbine. Whole turbine from the newer power plant has much higher energy and exergy efficiencies in comparison to whole turbine from an older power plant. In an older steam turbine, LPC did not show the expected performance because its exergy efficiency is very low (equal to 75.49%), what is much lower than in any other cylinder from both observed turbines. The ambient temperature change sensitivity of the two observed steam turbines and their cylinders is reverse proportional to efficiencies (both energy and exergy). Steam turbine from an older power plant is much more sensitive to the ambient temperature change.

  • Control-relevant identification of the DC engine coupled with a reaction wheel

    pg(s) 67-70

    This paper proposes to estimate the mathematical model of the DC motor coupled with a reaction wheel in two ways: open-loop identification and closed-loop identification. For open-loop identification, the experimental curve is approximated with the model of object with inertia first order, and inertia second order. In the case of closed-loop identification, it was obtained the model with inertia third order, that approximates the dynamic of the process, where the coefficients are calculated based on the simple analytical expressions according to the values that are extracted from the undamped step response of the closed-loop system with P controller. The results of the experimental model estimation were compared with the results obtained using the System Identification Toolbox from MATLAB. In addition, to the identified object model, it was proposed to tune a PID controller based on the maximum stability degree criterion.

  • Key Parameters in Zipline Design: An Analytical Approach

    pg(s) 62-66

    Zipline is an adventure activity that involves a steel cable suspended between two anchor points at varying heights and distances. Participants are secured to a trolley that moves along the cable, primarily driven by gravitational force. This sport, often classified as an adrenaline activity, has become increasingly popular for recreational use.
    This paper presents a comprehensive analysis of the key parameters influencing zipline systems, including the modelling of movement dynamics and the selection of essential components. Utilizing the principles of the catenary curve, our approach draws parallels with established methodologies in cable car and cable crane systems.
    To ensure the quality design and safe operation of zipline systems, it is crucial to analyse various factors, such as participant weight, rope anchoring methods, tension force, and angle of inclination, movement speed, release position, trolley wheel resistance, air resistance, temperature effects, and geographical considerations.
    As a case study, we detail the findings from a theoretical model, validated through computer simulations, focusing on the specific conditions of a zipline constructed in Theth, Albania. Our results provide valuable insights into the design and safety protocols necessary for effective zipline operations.

  • Analysis and Modelling of the Nonwoven Waste Fabric Cutting Unit

    pg(s) 59-61

    In this study, the design and modeling of a shredding unit intended to fragment nonwoven waste fabrics and prepare them for recycling were carried out. Stress analyses were performed on the shaft attached to the blade, along with motor power and torque analyses required for smooth operation, and mass flow calculations. Mathematical models were developed based on these data. Additionally, structural analyses of the chassis, necessary for stable system operation, were conducted, resulting in a comprehensive mathematical model of the entire system.

  • Effect of the limiting deformation zone under conditions of asymmetric loading during rolling

    pg(s) 56-58

    In this article, is to develop a physical and mathematical model of the process under complex asymmetric loading in conditions of single-area and two-area deformation zone during plastic processing of medium-thickness strips. The stress state in case of loss of stability during rolling of strips of medium thickness was investigated. The patterns of changes in the stress state of the strip under conditions of reach of the limiting deformation zone, as well as the effects of plastic shaping determined by a decrease in contact stresses under conditions of increasing deformation loading, are revealed. The described method is a visual approach to assessing the stress state of a plastic medium under conditions of complex interaction and asymmetric loading.

  • Modified Split Hopkinson Pressure Bar adapted to porous and low strength materials testing

    pg(s) 51-55

    A modified version of the Split Hopkinson-Kolsky Pressure Bar is described, intended for impact testing of porous metals and other low-strength materials. In it, one bar is made of aluminum alloy and the other bar is a steel tube. Several variants of the mathematical model for working with such devices are described. The stress-strain diagram of the specimen is extracted from the first impact signal. Attention has been paid to the approach to choosing the initial moments from which the calculations must start. Several examples are shown with solid and porous aluminum alloy samples. Despite the lack of high accuracy of the diagram at small stresses, the facility is suitable for quickly obtaining the overall appearance of the diagram after crushing small cylindrical specimens (up to 10 mm in diameter and height) and estimating the stresses at which the material deforms plastically.

  • Exploring the Impact of Component Materials on the Energy Efficiency of Solar Panels for Water Heating: A Numerical and Experimental Investigation using labview Software

    pg(s) 37-41

    This study examines the impact of component materials on the energy performance of solar panels designed for water heating. For this purpose, we have integrated numerical simulations and experimental analyzes enabled by algorithms developed with LabVIEW software. The primary objective of this investigation is to assess how the selection of materials in the construction of solar panels affects their overall efficiency in harnessing and converting solar energy into heat for water heating purposes. The research methodology involves the development and implementation of advanced algorithms using LabVIEW, a versatile software platform known for its proficiency in data acquisition, analysis, and control. Numerical simulations focus on modeling the behavior of solar panels under different conditions, taking into account factors such as radiation, temperature and the specific characteristics of different component materials. These simulations provide valuable assessments of theoretical aspects of solar panel performance and enable the identification of optimal material combinations. Through the physical model, experimental studies are conducted to validate the simulated results. Physical prototypes of solar panel components are built using various materials and their performance is rigorously evaluated under real-world conditions. Experimental measurements allow data collection, and enable comparative analysis with numerical simulations. The results of this study aim to contribute to the advancement of solar panel technology by providing a deeper understanding of how material choices affect energy efficiency. Moreover, the use of LabVIEW software in the development of algorithms ensures a systematic and accurate analysis of numerical and experimental data.

  • Advancing Machining Manufacturing: A Comprehensive Evaluation of Finite Element Method Simulation for Cutting Processes

    pg(s) 32-36

    Modeling and simulating cutting processes play a pivotal role in the advancement of machining manufacturing. This enables machining design technologists to scrutinize and optimize intricate machining processes before their implementation in manufacturing. The Finite Element Method (FEM) emerges as a robust numerical technique widely employed for simulating cutting processes in manufacturing. While FEM proves particularly well-suited for cutting simulation, it is imperative to make judicious choices regarding the FEM method and software for effective implementation in cutting simulations.
    The realm of FEM software is diverse, encompassing various analysis options such as mechanical, thermodynamic, and contact analyses. However, the selection of appropriate FEM software is not only contingent upon these analysis options but also influenced by factors like the user interface and the requisite understanding of the physical nature inherent in the modeled cutting process.
    In the scope of this study, a simplistic orthogonal cutting model is formulated utilizing the FEM software DEFORM and the FEM software MARC MENTAT. The attained results are meticulously evaluated by comparing them not only in relation to practical applicability but also considering the challenges and intuitiveness associated with the creation of a machining model.