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Strength analysis of steel structures supporting traffic control devices.
No full textSteel structures designed for mounting traffic control devices – traffic lights and associated equipment – are analysed in this thesis. The main aim of the work is to investigate the strength of these structures and to assess the possibilities of reducing their member cross-sections in order to achieve more efficient use of material. The theoretical part reviews scientific and technical literature on lightweight steel structures, their application to traffic light and road sign supports, and discusses the relevant requirements of Eurocodes and Lithuanian technical regulations as well as their application to the design of structures supporting traffic control devices. The methodological part describes the numerical modelling of three types of supports – a frame truss, a cantilever truss and a cylindrical-conical cantilever – using the software Autodesk Robot Structural Analysis Professional 2021 and the Finite Element Method. The models take into account the self-weight of the structure and the mounted equipment, wind and ice loads, and Ultimate Limit State load combinations are formed in accordance with Eurocode provisions and national regulations. In the research part it is determined that the initial support configurations are characterised by relatively low member utilisation ratios: the average utilisation of the frame truss members is about 7 %, of the cantilever truss – about 15 %, and of the cylindrical-conical cantilever – about 47 %, which indicates a high safety reserve and inefficient use of steel. Using a trial-and-error approach, smaller cross-sections of the support members are selected: bar diameters are reduced in the frame and cantilever truss structures, and tube wall thicknesses are reduced in the cylindrical-conical cantilever. After changing the profiles, the average utilisation ratio of the frame truss members increases to approximately 18 %, of the cantilever truss – to about 28 %, and of the cylindrical-conical cantilever – to about 60 %, while the utilisation ratios of the most highly loaded members approach but do not exceed the allowable limit. The results show that by rationally adjusting the cross-sections of support members without changing the topology of the structures, it is possible to significantly reduce steel consumption while maintaining the required structural reliability
Assessment of digital competence needs among STEAM teachers.
No full textGlobal digital transformation and the development of STEAM education are increasing the requirements for teachers' digital competence, which is also reflected in the strategic documents of the European Union and Lithuania, which emphasize the integration of digital skills into education. Scientific literature notes that the digital competence of educators is often assessed as average, and highlights the problem that professional development measures do not always meet the real needs of educational practice, making it important to accurately identify priority areas for improvement. The object of the study is the need for digital competence among STEAM teachers. The aim of the study is to assess the need for digital competence among STEAM teachers. The tasks of the work are: 1) to analyze the concept of digital competence; 2) to justify the need for digital competence among STEAM teachers in the educational process; 3) to examine models of digital competence among teachers and their areas; 4) to empirically assess the competence level and need for digital competence among STEAM teachers in the educational process. Data collection methods used in the work include analysis of scientific literature and quantitative written questionnaires. Data analysis was performed using descriptive statistics: the frequencies and percentage distributions of responses were determined, the means, standard deviations, and differences in the competence level and need for digital competence among STEAM teachers were calculated according to the six DigCompEdu areas. The internal consistency of the instrument was assessed and found to be reliable. The theoretical part of the work analyzes the concept of digital competence, the need for digital competence among STEAM teachers in the educational process, and examines models of digital competence among teachers (DigCompEdu, ISTE, UNESCO, STEAMCompEdu) and their areas. The results of the empirical study revealed high indicators of the need to improve the digital competence of STEAM educators in all six DigCompEdu areas, which consistently exceed the competence level results. The greatest need was recorded in the areas of competence focused on organizing student learning and developing their digital skills, while the smallest gap between competence level and need was seen in the area of professional activity. A sociodemographic analysis shows that the need to improve the digital competence of STEAM teachers is rated highly, regardless of age or length of service. More pronounced differences are revealed according to the subject taught – although the need for computer science, technology, and natural sciences subjects remains high, a greater gap between competence level and need is recorded in the groups of mathematics and arts teachers, indicating that teachers of these subjects are less prepared to apply digital technologies in the education and improvement process. The study indicates that the need to strengthen the digital competence of STEAM teachers is relevant in all areas of DigCompEdu
Fotopolimerų stingimo matematinis modelis.
No full textStereolithography is an additive manufacturing technique that fabricates three-dimensional objects with high speed and precision by selectively exposing a liquid photopolymer using a laser beam. It is most commonly applied in prototyping and the production of medical devices and implants. To achieve highly dimensional accuracy, stereolithography processes are typically described using physical models, chemical kinetic models, or hybrid approaches, while certain aspects of the process can also be optimized using machine learning. However, under high exposure conditions, the experimentally observed relationship between exposure and photopolymer cure depth – known as the working curve – occasionally deviates from classical models. One proposed mechanism for this deviation is the optical bleaching phenomenon: as the photopolymer cures, its optical properties change, allowing greater light penetration and increasing the exposure received by the uncured material. In this thesis, a data-driven approach is developed that extends a classical physics-based model to account for optical bleaching, and the model is validated using real experimental data. The extended model uses four parameters that are optimized in a two-stage function fitting process. Two parameters, identical to those in the original model, are extracted from the linear portion of the data, while two additional parameters are optimized from the full data. The performance of the extended model was evaluated using two experimental datasets comprising a total of 75 experiments. For fully linear experiments, both models achieved similar accuracy, indicating that the extended model does not deviate from the original formulation under normal conditions. For super-logarithmic cases, where the working curve increases at higher exposures, the extended model consistently outperformed the baseline. However, for the sub-logarithmic cases, where the working curve decreases with higher exposures, the extended model underperformed relative to the original model. These results indicate that optical bleaching effectively captures only the super-logarithmic behavior of the working curve. Finally, the consistency of the extended model was evaluated using three similar experiments, demonstrating that the model remains relatively stable under comparable conditions
Relationship between consumer religiosity, spirituality, minimalism and sustainable consumption behaviour intentions.
No full textThe dissertation investigates how consumers’ religiosity, spirituality and minimalism affect sustainable consumption behavioral intentions. Based on the belief compatibility theory, a model is developed in which consumer minimalism acts as a mediating mechanism between religiosity, spirituality and sustainable consumption behavioral intentions. The study is based on a post-positivist approach and PLS-SEM analysis (N=512). It has been confirmed that spirituality significantly increases consumer minimalism and has both a direct and indirect effect on sustainable consumption behavioral intentions. Consumer minimalism is also an independent, moderate predictor of sustainable consumption behavioral intentions. Religiosity does not promote consumer minimalism, its effect on sustainable consumption behavioral intentions is weak and only direct. The scientific novelty of the dissertation is an integrated model of religiosity, spirituality and consumer minimalism and an empirically based mediation of consumer minimalism. Practical implications – recommendations for policymakers, education, business and NGOs – value-based communication, integration of spirituality and consumer minimalism in educational and marketing decisions, promoting sustainable consumption. The dissertation complements research on consumer behavior and sustainability by showing that intrinsic values, in this case spirituality, promote sustainable consumption behavior intentions through consumer minimalism
Conceptual basis of adaptation of a field-oriented control system for traction induction motors to the operating parameters of a locomotive /
No full textField-oriented control (FOC) of induction motors (IMs) is used in railway rolling stock. In such control systems, a fixed frequency of the pulse-width modulation (PWM) inverter is used, which leads to an increase in power losses in the traction drive. To optimize power losses in the locomotive traction drive system, it is proposed to adapt the number of PWM inverter pulses to the frequency of the FOC speed controller, which is proportional to the locomotive speed. To solve this problem, conceptual foundations for adapting FOC to the locomotive speed have been developed, the key aspects of which are algorithms for adapting the PWM inverter frequency, the controller parameters and the parameters of the FOC speed controller frequency filters. The most significant results of the work are the methods for adjusting the maximum of the controllers of the basic FOC IM system, the filter structure and the inverter control scheme, adapted to the locomotive speed. The modeling results have shown the effectiveness of the proposed technical solutions. The proposed approach to developing FOC will allow minimizing the consumption of energy resources by the locomotive in the entire range of changes in its speed
Consecutive recovery of bioactive substances from Desmodium canadense at different plant vegetation phases by green extraction with supercritical CO2 and increasing polarity pressurized liquids /
No full textThis study used high-pressure extraction to obtain antioxidant-rich fractions from Desmodium canadense leaves harvested at five vegetation phases (intensive growing to end of blooming) and to evaluate their antioxidant activity and phytochemical profile. Supercritical CO2 extraction recovered lipophilic compounds, with the highest yield at massive flowering. The remaining plant material was fractionated by pressurized liquid extraction (PLE) using acetone, ethanol, and water; the highest PLE yield was achieved with water (16.54 g/100 g DW) at the bud formation stage. Antioxidant capacity was measured using total phenolic content (TPC) and ABTS•+, CUPRAC, and ORAC assays. Overall, ethanol PLE extracts showed the strongest antioxidant properties: maximum TPC (282.1 mg GAE/gE) and ABTS•+ (1010 mg TE/gE) at massive flowering, and highest CUPRAC (853.3 mg TE/gE) and ORAC (1882 mg TE/gE) at bud formation. UPLC-Q-TOF-MS/MS profiling identified 37 compounds, mainly C-glycosyl flavones, flavonol O-glycosides, hydroxycinnamic acid derivatives, and low molecular weight organic acids. Water extracts were rich in low molecular weight organic acids, while acetone and ethanol extracts contained the highest flavonoid levels. Citric acid and vitexin were the most abundant compounds. The findings indicate that D. canadense leaves, especially harvested at budding through massive flowering, are a promising source of flavonoid-rich antioxidant extracts for nutraceutical and functional food applications
Transformer-based foundation learning for robust and data-efficient skin disease imaging /
No full textBackground/Objectives: Accurate and reliable automated dermoscopic lesion classification remains challenging. This is due to pronounced dataset bias, limited expert-annotated data, and poor cross-dataset generalization of conventional supervised deep learning models. In clinical dermatology, these limitations restrict the deployment of data-driven diagnostic systems across diverse acquisition settings and patient populations. Methods: Motivated by these challenges, this study proposes a transformer-based, dermatology-specific foundation model. The model learns transferable visual representations from large collections of unlabeled dermoscopic images via self-supervised pretraining. It integrates large-scale dermatology-oriented self-supervised learning with a hierarchical vision transformer backbone. This enables effective capture of both fine-grained lesion textures and global morphological patterns. The evaluation is conducted across three publicly available dermoscopic datasets: ISIC 2018, HAM10000, and PH2. The study assesses in-dataset, cross-dataset, limited-label, ablation, and computational-efficiency settings. Results: The proposed approach achieves in-dataset classification accuracies of 94.87%, 97.32%, and 98.17% on ISIC 2018, HAM10000, and PH2, respectively. It outperforms strong transformer and hybrid baselines. Cross-dataset transfer experiments show consistent performance gains of 3.5-5.8% over supervised counterparts. This indicates improved robustness to domain shift. Furthermore, when fine-tuned with only 10% of the labeled training data, the model achieves performance comparable to fully supervised baselines. Conclusions: This highlights strong data efficiency. These results demonstrate that dermatology-specific foundation learning offers a principled and practical solution for robust dermoscopic lesion classification under realistic clinical constraints
More than money: strategic and operational innovation capabilities to promote technological innovation through crowdfunding /
No full textCrowdfunding delivers far more than financial capital when ventures possess the right innovation capabilities. Drawing on the dynamic-capability view, transaction-cost economics, and knowledge-based view, we theorize that strategic (dynamic scanning, seizing, and reconfiguring) and operational (digitalization, investment, and networking) capabilities jointly propel firms’ technological innovation and that this propulsion is channeled through digital-platform trust and crowdfunding. Primary data from 164 technology-oriented start-ups and SMEs were analyzed via partial least-squares structural equation modeling. The results confirm that digitalization, networking, and dynamic capabilities each exert positive direct effects on technological innovation; however, their total impact is significantly amplified when digital trust first converts capabilities into successful crowdfunding campaigns, which in turn finance and legitimize experimentation and learning. Investment capability, in contrast, exhibits no independent effect once strategic and operational capabilities are taken into account, underscoring that money alone is insufficient. The model explains 43% of the variance in digital trust and 69% in technological innovation. The study advances theory by specifying a two-stage capability-trust-crowdfunding pathway that links financial-innovation scholarship with innovation-management research and by demonstrating the complementary roles of strategic sensing-seizing-reconfiguring routines and operational digital and network assets under Industry 4.0 conditions. Practically, the findings advise entrepreneurs to build credible digital-trust architectures and partner networks before they seek crowdfunded capital and guide platform providers and policymakers in designing trust-enhancing mechanisms that translate funding into sustained innovative output in the form of technological learning and its upgrading
Impact of technostress on work-life balance across different work organization forms.
No full textThis Master’s final degree project analyzes the impact of technostress on work–life balance across different work organization forms. Accelerating digital transformation, the expansion of remote and hybrid work, and a culture of constant availability have increased technology-induced psychological pressure, which has become a significant challenge for employee well-being and professional sustainability. Technostress is increasingly associated with the blurring of boundaries between work and personal life, emotional exhaustion, and a reduced ability to psychologically detach from work during non-working time, particularly in technology-driven work environments. The aim of the project is to determine the impact of technostress on work–life balance across different work organization forms. The object of the research is the impact of technostress on work–life balance. The study is based on a scientific literature review and a quantitative research approach using a questionnaire survey. Technostress is conceptualized as a multidimensional construct encompassing techno-overload, techno-invasion, techno-insecurity, techno-uncertainty, and techno-complexity, while work–life balance is analyzed with respect to different work organization forms, namely traditional, remote, and hybrid work. The study was conducted in the financial sector, as this field is characterized by intensive use of information and communication technologies and a diversity of work organization forms. The results of the study indicate that technostress has a statistically significant negative impact on work–life balance among respondents working in the financial sector. It was found that technoinvasion and techno-overload have the strongest negative effects on work–life balance, particularly under remote and hybrid work conditions, where the boundaries between work and personal life become less defined. The findings also revealed that respondents working remotely or in hybrid arrangements experience greater difficulties in detaching from work after working hours compared to those working in traditional work settings. Regression analysis results demonstrate that work organization form moderates the relationship between technostress and work–life balance in the studied sample, highlighting the importance of work organization decisions. The results of this Master’s thesis may be useful for organizations in the financial sector and human resource management professionals seeking to reduce the negative impact of technostress on the wellbeing of employees working in this sector, strengthen the management of work–rest boundaries, and develop more sustainable work organization practices. The study also contributes to the development of technostress and work–life balance research in the Lithuanian context by expanding the empirical research base and providing directions for future studies
Factors shaping the innovation culture in food industry enterprises.
No full textFood industry is facing increasingly stringent food safety and sustainability requirements, along with constantly changing consumer expectations. In the Lithuanian context, the relevance of innovation is further strengthened by the strategic direction of the agri-food sector, which aims to increase the share of life sciences (including agri-food) in GDP to 5% by 2030 through innovation, sustainability, and digitalization. Innovation outcomes are determined not only by technological investments but also by innovation culture factors that create conditions for innovations. Although research on innovation culture has been done across various contexts, literature still lacks studies on the factors shaping innovation culture in specific manufacturing sectors such as the food industry. The object of the master's thesis is the factors shaping innovation culture in the food industry, the aim – to identify the factors influencing the formation of innovation culture in the food industry. Based on literature, a model of factors shaping the innovation culture was developed. The model distinguishes between internal and external factors. Internal factors include leadership, structural and strategic orientations, psychological safety, empowerment and creativity, risk tolerance, market orientation, collaboration and learning, and technological capabilities. External factors include national culture, government support, market dynamics and competition. To substantiate the theoretical model, a research methodology was developed, a qualitative research method was selected – semi-structured interviews involving 11 managers and 4 employees from a single food industry enterprise. Also, an expert ranking of the identified factors was conducted. The research results showed that innovation culture is primarily shaped by internal organizational factors, while external factors function mainly as a contextual background. Leadership was identified as the key factor through which other factors are integrated. Given the high level of regulatory risk, innovation culture in the food industry must be structured and goal-oriented: creativity should be balanced with structural discipline, and innovations should be consistently linked to value creation and risk assessment. Psychological safety in the food industry functions as a practical space. The maturity of innovation culture is determined by the ability to manage risk effectively. The study found that innovations most often arise from everyday practices and incremental improvements. However, the speed of innovation may be constrained by information loss, silo effects, and KPI conflicts. The results of the factor ranking indicated that the most important factors are leadership, psychological safety, and empowerment and creativity, while national culture and government support were rated as the least important. Market dynamics and competition emerged as the strongest external pressure factor. Based on the research insights, it is recommended that the organization strengthen its capacity dedicated to innovation, more clearly define the boundaries of psychological safety in the food industry context, improve the management of decision-making speed in cases of larger innovations, and enhance collaboration in order to reduce information loss and accelerate the implementation of innovations