https://etalpykla.vilniustech.lt/handle/123456789/160338 2026-05-31T08:01:56Z https://etalpykla.vilniustech.lt/handle/123456789/160442 UAV-based rock mass characterization for Geological Strength Index (GSI) assessment and comparison with conventional field mapping Husaini, Ahmad Zharfan Ahmad; Rathinasamy, Vynotdni; Roslee, Mohamad Syazwan Mohd; Ismail, Mohd Ashraf Mohamad; Bhatawdekar, Ramesh Murlidhar; Hasbollah, Dayang Zulaika Abang; Suparmanto, Eka Kusmawati; Jialiang, Luo Rock mass characterization is essential for reliable Geological Strength Index (GSI) estimation, particularly in inaccessible or steep slopes where conventional field mapping is challenging. This study evaluates the feasibility of utilizing Unmanned Aerial Vehicle (UAV)-based photogrammetry for GSI assessment using the Cai et al. (2004) chart in a granitic outcrop in Machang, Kelantan, Malaysia. Quantitative parameters, including block volume (Vb) and joint roughness, were derived from 3D point clouds, while joint condition factors (Jc) were assessed through both manual and UAV approaches. Results show strong correlation between UAV and manual assessments (R² = 0.9894 for GSI). The findings demonstrate that UAV-based methods can reliably replace conventional field mapping, improving safety, efficiency, and data density for GSI assessment of Cai et al. (2004). 2026-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/160429 Heat balance analysis for an electric car Rusowicz, Artur; Kowalski, Bartosz The paper focuses on the analysis and simulation of thermal management systems in electric vehicles. In the computational section, heat exchange in the passenger cabin and the electric drive system was modeled using advanced engineering software Siemens Amesim. These models were employed to simulate the cabin’s heat balance and to calculate heat losses in the drive system in order to determine the thermal load on the cooling and air conditioning systems. Based on the results, the impact of operating conditions on heat exchange with the environment was analyzed, and directions for further development of cooling systems in electric vehicles were proposed. A well-described Tesla Model SR 2021 RWD electric vehicle was analyzed. Calculations were performed for three variants, one with a stationary vehicle, the second with a variable ambient temperature, and the third with a variable vehicle speed. The calculations revealed a significant impact of ambient temperature on heat flows penetrating the car’s structure, and in the case of increasing car speed, a significant demand for battery and engine cooling. 2026-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/160428 Thermal performance of a silica gel-water vapor adsorption system as an alternative cooling technology Katana, Katarzyna; Szelągowski, Adam; Grzebielec, Andrzej Adsorption-based cooling is an alternative to conventional vapor-compression systems that have a high environmental impact and account for a significant share of global energy consumption. This study presents an experimental and analytical investigation of a two-bed adsorption cooling system operating with a water/silica-gel working pair. The device consists of a refrigerant circuit (water vapor) and a secondary water circuit that provides supplies or removes heat from the beds when necessary. The refrigerant circuit includes two adsorption beds, a condenser, an expansion valve, and an evaporator. The system operates in alternating half-cycles, with one bed undergoing desorption while the other performs adsorption. Measurements of temperature, pressure, and volumetric flow rates were conducted over nearly three half-cycles. Theoretical cooling capacity was calculated at 6.652 kJ, which corresponds to the EER (Energy Efficiency Ratio) equal to 0.0405. To overcome issues associated with limited thermal contact between the surface of the heat exchanger and the adsorbent particles as well as low thermal conductivity of silica gel, it should be applied directly onto the heat exchanger’s surface in the form of coatings instead of the traditional loose packing of adsorbent granules. Additionally, enhancing the system’s performance can be achieved by implementing heat and mass recovery. These findings provide insights into the design of adsorption-based refrigeration, emphasizing environmentally friendly and efficient alternatives to conventional vapor-compression systems. 2026-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/160427 Riverbed monitoring and modeling using GIS Bražiūnas, Rokas; Puzienė, Rūta; Sužiedelytė-Visockienė, Jūratė The study aims to assess the changes in the riverbed that have occurred in various periods using GIS technologies. Topographic maps of different years will be used for the analysis. The riverbed has been digitized (for each period), determining the change in displacement and dislocation. The assessed dynamics of changes allow us to monitor the changes in the riverbed that have occurred due to both natural processes and anthropogenic impact. By performing two-dimensional and three-dimensional modeling, the spatial extent and intensity of the bed change were visualized. The results obtained reflect the relationship between riverbed transformations and potential natural and anthropogenic factors, allowing us to assess long-term trends in river morphology change. 2026-01-01T00:00:00Z