https://etalpykla.vilniustech.lt/handle/123456789/101055 2026-04-07T06:55:01Z https://etalpykla.vilniustech.lt/handle/123456789/153843 Optimum fines content in manufactured sand for best overall performance of superplasticized concrete / Chen, J. J.,; NG, Pui Lam,; Kwan, A. K. H., Due to a shortage of river sand for concrete production, manufactured sand (MS) made from crushed rock has gradually become a substitute. It inherently contains some fines content, which has significant effects on the performance of concrete. To study the effects of the MS type and fines content on the workability, cohesiveness, and strength, concrete mixes made with granite MS or limestone MS and different fines contents at various water/binder ratios were tested. Moreover, the packing density, water film thickness (WFT), paste film thickness (PFT), and microstructures of the concrete mixes produced were examined to investigate if their changes were the root causes of the effects of the MS used. It was found that the use of granite MS attained higher workability and strength but lower cohesiveness, which apparently were caused by the higher packing density and larger WFT and PFT. Also, regardless of the MS type, a fines content of about 10% was the optimum for highest packing density and best concurrent workability-cohesiveness-strength performance. Correlation analysis revealed that the MS and fines content exerted their influences on the workability and cohesiveness through the WFT and PFT, and on the strength through the packing density and microstructure. 2024-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/153842 Essential oils of Mentha arvensis and Cinnamomum cassia exhibit distinct antibacterial activity at different temperatures in vitro and on chicken skin / Vepštaitė-Monstavičė, Iglė,; Ravoitytė, Bazilė,; Būdienė, Jurga,; Valys, Algirdas,; Lukša, Juliana,; Servienė, Elena, The bacterial contamination of meat is a global concern, especially for the risk of Salmonella infection that can lead to health issues. Artificial antibacterial compounds used to preserve fresh meat can have negative health effects. We investigated the potential of natural essential oils (EOs), namely Mentha arvensis (mint) and Cinnamomum cassia (cinnamon) EOs, to prevent contamination of the food pathogen, Salmonella enterica subsp. enterica serotype Typhimurium, in vitro and on chicken skin. The gas chromatography–mass spectrometry (GC-MS) technique was used to determine the compositions of mint EO (MEO) and cinnamon EO (CEO); the most abundant compound in MEO was menthol (68.61%), and the most abundant compound was cinnamaldehyde (83.32%) in CEO. The antibacterial activity of MEO and CEO were examined in vapor and direct contact with S. typhimurium at temperatures of 4 °C, 25 °C, and 37 °C. The minimal inhibitory concentration at 37 °C for MEO and CEO reached 20.83 µL/mL, and the minimal bactericidal concentration of CEO was the same, while for MEO, it was two-fold higher. We report that in most tested conditions in experiments performed in vitro and on chicken skin, CEO exhibits a stronger antibacterial effect than MEO. In the vapor phase, MEO was more effective against S. typhimurium than CEO at 4 °C. In direct contact, the growth of S. typhimurium was inhibited more efficiently by MEO than CEO at small concentrations and a longer exposure time at 37 °C. The exploration of CEO and MEO employment for the inhibition of Salmonella bacteria at different temperatures and conditions expands the possibilities of developing more environment- and consumer-friendly antibacterial protection for raw meat. 2023-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/153844 A novel robust adaptive neuro-sliding mode steering controller for autonomous ground vehicles / Hajjami, Lhoussain El,; Mellouli, El Mehdi,; Žuraulis, Vidas,; Berrada, Mohammed, This paper intends to harness recent advances in intelligent commands to develop a novel steering control strategy for autonomous ground vehicles (AGVs) maneuvering problems. In this research, the vehicle is embodied by a single track-model (ST) taking into consideration its lateral dynamics. Besides, it is subject to unknown disturbances and uncertainties, associated with the tire/road adhesion coefficient, which are upper bounded by a positive limit. An on-line Radial Basis-function Neural-Networks (RBNN) adaptive mechanism is designed to estimate this upper limit in the sense of Lyapunov. On this basis, a novel robust adaptive neuro-sliding mode steering angle controller (AN-SMC) is introduced. Whilst the effectiveness of the controller is impacted by its parameters, a new neural-network optimization algorithm (NNA) is employed to provide optimal values for these settings. The proposed approach is evaluated through a single lane-change-maneuver planned out by a new methodology. The steering controller revealed a powerful path-tracking via the comparisons carried out in support of the developed strategy. 2023-01-01T00:00:00Z https://etalpykla.vilniustech.lt/handle/123456789/153845 Efficiency and challenges in public real estate management: insights from Lithuania / Cohen, Viktorija,; Bereznauskė, Evelina,; Burinskas, Arūnas,; Raslanas, Saulius, Public real estate is considered an integral part of national wealth. It generates a wide range of economic activities that contribute to creating and providing common public goods. This study examines the efficiency of public real estate management in Lithuania. Our findings show that public property use, disposal, and management strongly depend on the managerial approach. We apply data envelopment analysis (DEA) in addition to the income value, regression, and correlation methods. We find that there are certain biases present due to the exclusion of some state-owned properties from the public register. Furthermore, we identify the need for greater precision in the indicators used for financial reporting of state-owned assets. The excessive number of vacant asset units poses a challenge, as it requires substantial maintenance expenditures. Moreover, the appraisal of alternative use of these assets is lacking, thereby limiting the potential for maximizing public benefits. Our analysis reveals that the rental price per 1 m2 and the residual value of the leased premises are the most critical determinants influencing the management efficiency of publicly owned property. Furthermore, it is evident that the residential property is the only type of state-owned property managed efficiently within the Lithuanian public sector. These findings underscore the importance of formation of robust public real estate policies. 2023-01-01T00:00:00Z