Bialystok University of Technology

The search for low-emission fuels has increased interest in hydrotreated vegetable oil (HVO) as a renewable diesel substitute. This study examines the lubricity of HVO, diesel, and their blends using a four-ball tester, with scuffing load as the main evaluation criterion. Five fuel samples were tested: diesel, neat HVO, and blends containing 25%, 50%, and 75% HVO by volume. The results show that blending HVO with diesel improves lubricity at moderate concentrations, with the 25% HVO blend exhibiting the highest scuffing load. In contrast, neat HVO demonstrated significantly reduced lubricity—its scuffing load was 24% lower than diesel’s—confirming the negative impact of the absence of polar and aromatic compounds. The scuffing load did not decrease linearly with increasing HVO content, suggesting synergistic effects in certain blends. Viscosity increased with HVO content, but it did not directly correlate with improved lubricity. These findings indicate that chemical composition plays a dominant role over viscosity in determining lubricating performance. The study provides new insights into the tribological behavior of HVO–diesel blends and demonstrates that scuffing load testing offers a practical method for preliminary lubricity assessment of renewable fuels.

Hubert Kuszewski; Artur Jaworski; Dariusz Szpica. Comparative Study of the Lubricity of Hydrotreated Vegetable Oil, Diesel, and Their Blends Using Four-Ball Testing: Focus on Scuffing Load. Energies 2025, 18, 3141 .

Hubert Kuszewski, Artur Jaworski, Dariusz Szpica. Comparative Study of the Lubricity of Hydrotreated Vegetable Oil, Diesel, and Their Blends Using Four-Ball Testing: Focus on Scuffing Load. Energies. 2025; 18 (12):3141.

Hubert Kuszewski; Artur Jaworski; Dariusz Szpica. 2025. "Comparative Study of the Lubricity of Hydrotreated Vegetable Oil, Diesel, and Their Blends Using Four-Ball Testing: Focus on Scuffing Load." Energies 18, no. 12: 3141.

Increasing requirements for reducing energy consumption result in thermo-modernisation existing buildings. Modernized buildings have significantly lower transmittation coefficient; infiltration air rate slows down markedly, which may lower indoor air quality (IAQ) noticeable; one gauge with a vane probe measures the air velocity and temperature at a grille in the toilet; second gauge with IAQ probe located in a room measures the mole fraction of carbon dioxide, dry-bulb and wet-bulb temperatures, absolute pressure, and humidity; moreover there are estimated the measurements uncertainties of: the volume flow rate, mole fraction of CO2, temperatures, and humidity. IAQ in a dwelling after thermo-modernization is evaluated in a sixty-year old building; heating system ensures thermal comfort during heating season; ventilation performs poorly, for vapor condenses on the window; carbon dioxide concentration is too high, which curbs mental activity greatly.

Klaudia Domalewska; Andrzej Gajewski. Impact of Ventilation Performance on Human Behaviour: A Case Study After Apartment Building Thermo-Modernization. Preprints.org 2025 .

Klaudia Domalewska, Andrzej Gajewski. Impact of Ventilation Performance on Human Behaviour: A Case Study After Apartment Building Thermo-Modernization. Preprints.org. 2025; ():.

Klaudia Domalewska; Andrzej Gajewski. 2025. "Impact of Ventilation Performance on Human Behaviour: A Case Study After Apartment Building Thermo-Modernization." Preprints.org , no. : .

This study presents a comprehensive analytical–numerical approach to determining the elastic–plastic properties of Hybrid Metal Matrix Composites (HMMCs), contrasting with prior research that primarily emphasizes elasticity. Using the finite element method (FEM) and elasticity and plasticity theory, we determined key parameters, including Young’s modulus, Poisson’s ratio, yield strength, and ultimate tensile strength. The method, which also accounts for strain-hardening behavior via the Hollomon model, enables precise simulation of HMMC with randomly distributed reinforcement particles of varying shapes and sizes, offering a realistic representation of the composite microstructure. Verification against the literature confirms the accuracy of the approach in reflecting both elastic and plastic behavior, providing essential insights into the material’s full mechanical response, particularly yield strength and strain-hardening properties, aspects rarely explored in depth in existing studies on HMMCs.

Grzegorz Mieczkowski; Dariusz Szpica; Andrzej Borawski. Comprehensive Analysis of Elastic–Plastic Behavior in Hybrid Metal Matrix Composites with Varied Reinforcement Geometry. Materials 2025, 18, 2763 .

Grzegorz Mieczkowski, Dariusz Szpica, Andrzej Borawski. Comprehensive Analysis of Elastic–Plastic Behavior in Hybrid Metal Matrix Composites with Varied Reinforcement Geometry. Materials. 2025; 18 (12):2763.

Grzegorz Mieczkowski; Dariusz Szpica; Andrzej Borawski. 2025. "Comprehensive Analysis of Elastic–Plastic Behavior in Hybrid Metal Matrix Composites with Varied Reinforcement Geometry." Materials 18, no. 12: 2763.