MECHANICAL ENGINEERING – SCIENTIFIC JOURNAL

700.NUMERICAL INVESTIGATION OF AERODYNAMIC EFFICIENCY IN AN AIRFOIL TANDEM CONFIGURATION

Sakova Haritina, Lazarevikj Marija, Markov Zoran — Tue, 30 Jun 2026 00:00:00 +0000

Tandem airfoils, used in the fields of aerodynamics for race cars and aircraft designs, are a key part of current research due to the aerodynamic complexity they introduce, while offering performance benefits.A numerical 2D CFD analysis of a tandem airfoil system was performed in this paper to determine their optimal position-ing for achieving maximum aerodynamic efficiency and analyzing the resulting flow field. Simulations were conducted in Ansys Fluent using a high-quality mesh and refined boundary layer conditions, targeting y+<1. Key parameters analyzed include the lift coefficient CL, drag coefficient CD, theCL/CD ratio, and flow visualizations such as pressure, velocity, streamlines, velocity vectors, and turbulent kinetic energy. Results indicate that the optimal angle of attack for the variable airfoil is -25°, where the highes CL/CD ratio is obtained. However, flow visualizations show wake formation at this angle, highlighting the need for further aerodynamic optimization to balance efficiency and wake reduction.

701.ASSESSMENT OF AIR QUALITY MANAGEMENT STRATEGIES IN SKOPJE: LONG-TERM PM TRENDS AND REGULATORY COMPLIANCE 2016–2025

Tue, 30 Jun 2026 00:00:00 +0000

Air quality remains a persistent challenge in urban environments, particularly in cities with complex emission structures and seasonal variability. This paper investigates air quality management strategies in Skopje from 2016 to 2025, emphasizing particulate matter (PM) concentrations and long-term pollution trends. The methodology integrates multi-year monitoring data with statistical processing, graphical interpretation, and an assessment of domi-nant emission sources. A significant portion of the study evaluates the relationship between national regulatory prac-tices and the European Union framework to determine practical alignment. By synthesizing technical observations with the regulatory context, this paper offers a grounded perspective on the evolution of air quality management over the analyzed decade.

702.THE ROLE OF RENEWABLE ENERGY SOURCES AND BATTERY ENERGY STORAGE SYSTEMS IN ENHANCING CRITICAL INFRASTRUCTURE RESILIENCE

Gjorgjievska Teodora, Stamatoska Simona, Manev Nikola, Kostadinova Tajana — Tue, 30 Jun 2026 00:00:00 +0000

The resilience of critical energy infrastructure has become an increasingly important component of national security, particularly in the context of growing energy demand, geopolitical uncertainty, and the ongoing transition toward renewable energy systems. In North Macedonia, the partial blackout of 18 May 2025 exposed vul-nerabilities within the national power system when an overvoltage event resulted in the separation of the 400 kV and 110 kV networks and the loss of approximately 79% of the national electrical load. The event highlighted the potential consequences of infrastructure disruptions on the continuity of essential services and the functioning of society. This paper examines the role of renewable energy sources (RES) and battery energy storage systems (BESS) in enhancing the resilience of critical infrastructure. Using a resilience-based framework grounded in critical infrastructure protection principles, the study analyzes how decentralized renewable generation, energy storage technologies, and microgrid architectures can reduce vulnerability to technical failures, supply disruptions, and cascading effects within the elec-tricity sector. In particular, emphasis is given to the contribution of solar photovoltaic systems, wind energy, and BESS in improving operational flexibility, supporting voltage and frequency stability, strengthening energy security, and enabling the continued operation of critical facilities during grid disturbances. The analysis demonstrates that the stra-tegic integration of RES and BESS can enhance the robustness and adaptive capacity of critical energy infrastructure by reducing dependence on centralized generation and imported fossil fuels while increasing the ability of the power system to withstand and recover from disruptive events. The paper argues that renewable energy technologies and energy storage should be considered not only as instruments of decarbonization but also as key components of national resilience and critical infrastructure protection strategies.

703.DESIGN AND DEVELOPMENT OF A LOW-COST ENVIRONMENTAL MONITORING SYSTEM FOR UNIVERSITY CAMPUS APPLICATIONS

Tue, 30 Jun 2026 00:00:00 +0000

This paper presents the design and framework development of a low-cost IoT-based multi-param-eter air quality monitoring network for smart campus applications, including its hardware and software architecture and an initial evaluation of the proposed prototype. The proposed system is designed to measure key environmental param-eters, including particulate matter (PM1, PM2.5, PM10), ambient noise levels (dB), temperature and barometric pressure. The system is based on cost-effective hardware components and integrates wireless communication technologies to enable real-time data transmission. The system enables continuous monitoring while remaining user-friendly and easy to deploy. Unlike traditional monitoring systems, which rely on large and expensive equipment installed at fixed locations, the proposed system is compact and portable, allowing deployment across different locations and enabling users to monitor environmental conditions in real time, while also providing indicative insights into potential changes in measured levels. Experimental validation of the noise sensing module demonstrated good agreement with a reference sound level meter, indicating the suitability of the proposed system for indicative environmental monitoring applica-tions.

704.DESIGN AND EXPERIMENTAL ANALYSIS OF LOW-COST AUTOMATED SOLAR TRACKING SYSTEM

Tue, 30 Jun 2026 00:00:00 +0000

This paper presents a low cost dual-axis light tracking prototype developed as a basis for future photovoltaic (PV) solar tracker systems. The device uses an Arduino microcontroller and four light resistors (LDRs) arranged in four sensing quadrants. The controller continuously samples and compares the quadrant signals to estimate the light direction and drives two SG90 servo motors to position the platform in azimuth and elevation. To improve stability and reduce unnecessary actuation, the control strategy applies averaged sensor sampling, differential error evaluation, and a tunable tolerance band (dead zone) that suppresses micro-adjustments under small intensity variations. This prototype is more energy efficient and simple to implement, making it suitable for educational demonstrations and preliminary research. Future work will integrate a photovoltaic module (solar panel) and external electrical measurements to quantify the improvements in energy yield over fixed - tilt configurations.

Under Cover

Jovanovski Bogdan — Tue, 30 Jun 2026 00:00:00 +0000

Under Cover

Impresum

Jovanovski Bogdan — Tue, 30 Jun 2026 00:00:00 +0000

Impresum

Jovanovski Bogdan — Tue, 30 Jun 2026 00:00:00 +0000

Table of Contents

INSTRUCTIONS FOR AUTHORS

Jovanovski Bogdan — Tue, 30 Jun 2026 00:00:00 +0000

INSTRUCTIONS FOR AUTHORS