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Design and investigation of a passive-type microfluidics micromixer integrated with an archimedes screw for enhanced mixing performance /
No full textIn recent years, microfluidics has emerged as an interdisciplinary field, receiving significant attention across various biomedical applications. Achieving a noticeable mixing of biofluids and biochemicals at laminar flow conditions is essential in numerous microfluidics systems. In this research work, a new kind of micromixer design integrated with an Archimedes screw is designed and investigated using numerical simulation and experimental approaches. First, the geometrical parameters such as screw length (l), screw pitch (p) and gap (s) are optimized using the Design of Expert (DoE) approach and the Central Composite Design (CCD) method. The experimental designs generated by DoE are then numerically simulated aiming to determine Mixing Index (MI) and Performance Index (PI). For this purpose, COMSOL Multiphysics with two physics modules—laminar and transport diluted species—is used. The results revealed a significant influence of screw length, screw pitch and gap on mixing performance. The optimal design achieved is then scaled up and fabricated using a 3D additive manufacturing technique. In addition, the optimal micromixer design is numerically and experimentally investigated at diverse Reynolds numbers, ranging from 2 to 16. The findings revealed the optimal geometrical parameters that produce the best result compared to other designs are a screw length of 0.5 mm, screw pitch of 0.23409 mm and a 0.004 mm gap. The obtained values of the mixing index and the performance index are 98.47% and 20.15 Pa−1, respectively. In addition, a higher mixing performance is achieved at the lower Reynolds number of 2, while a lower mixing performance is observed at the higher Reynolds number of 16. This study can be very beneficial for understanding the impact of geometrical parameters and their interaction with mixing performance
Assessment of heritage building renovation and modernization solutions using sustainability and digitization principles.
No full textThe growing focus on sustainability and comfort in buildings is encouraging new opportunities to implement these ideas. More and more researchers and practitioners are focusing not only on sustainable and comfortable design of new buildings, but also on sustainable renovation of existing buildings to ensure a good indoor microclimate. Cultural heritage buildings are continuously being renovated to preserve and maintain them, and the use of Building Heritage Information Modelling (HBIM) technology in renovation is increasing. Although, as the results of the literature analysis show, HBIM technology is so far mainly used to reconstruct the geometry of the structure, the model is not further used for energy or life-cycle analyses. The aim of this study is to identify the benefits of digital tools for the maintenance and sustainability of microclimate conditions in heritage buildings. The developed model is used in life cycle and microclimate studies using digital tools. The cultural heritage building selected for the study is the house of Miko and Kipras Petrauskas in Kaunas. The building was designed in 1924 and renovated in 2008. In 2001 the building was included in the Lithuanian cultural heritage list. The building is characterised by its inter-war architecture and the main structures consist of reinforced concrete elements, silicate brickwork, metal and wooden beams. Based on a photogrammetric model defining the external contours of the building, a laser scanning model defining the internal contours and the available material for the renovation project, an information model of the building is created. The reliability of the developed building information model is assessed by comparing the volume, length, height and width values of the model with those of the photogrammetric model. Also, the in-site data collected during the warm and cold seasons in the building under analysis, analysed during the study, reveal the problem of relative humidity during the cold season. During the cold season, the average relative humidity is 31,5% and does not meet the minimum regulated values. Using the developed HBIM model, the relative humidity problem is solved using the digital IDA ICE tool. Simulations of the building's microclimate were made by selecting a ventilation system with different types of heat exchanger and an additional humidification section. According to the data obtained, the best results are achieved by installing a ventilation unit with a humidification section, with an average relative humidity of 45,5 %. The life cycle analysis for the whole building and the renovated part of the building shows corresponding CO2e emissions of 357.8 t and 108.6 t respectively. The most polluting materials used during the renovation were found, with concrete accounting for 33,7 % of the total emissions, and aluminium partitioning and parquet flooring accounting for 21,4 % and 14,3 % of the total emissions generated during the renovation. Replacing the materials used in the renovation with more sustainable materials with the same or similar properties reduced the total amount of pollution generated by 24 tonnes or 22 %. The study demonstrates the usefulness and applicability of the HBIM and can be used as a good practice for similar studies or for the practical application of the described methods
Statybos projektų logistikos optimizavimas taikant tiesinio programavimo metodą.
No full textThe purpose of this thesis is to solve the network flow problem of 12 road construction sites. The thesis includes six main parts. In the first section a literature review is conducted to find the research gaps, the trending topics related to optimization of logistics, and to investigate the flow of research through the years on this topic. In this part of the thesis, a total of 52 papers were summarized and classified by the optimization method used. At the beggining of this chapter shows the PRISMA flowchart. After choosing the optimization method of linear programming, the section related to it is expanded further compared to other optimization methods. The second part is methodology, and the mathematical aspects of linear programming are studied. It is very crucial to know every aspect of the problem so that the errors can be managed. The third part is the research and results. Three logistic scenarios are introduced and the mathematical models and corresponding results are presented. The scenarios differ in the arrangement of the logistic nodes and edges, and for each scenario, the transportation cost, the CO2 emission cost, and the loading and unloading of aggregates are calculated. In the fourth section conclusions are drawn based on the analysis and findings in the previous sections. The fifth section is the list of references, and finally, the last section is the Appendix for the codes
The influence of manager's leadership style on employees' organizational commitment in the health care sector.
No full textRelevance of the topic. An analysis of scientific literature and research revealed that the healthcare sector faces challenges such as a shortage of healthcare professionals, migration and turnover of existing staff, complex bureaucratic mechanisms, heavy workloads, and burnout syndrome. Researchers unanimously agree that the institution's well-being and functionality depend on the leadership effectiveness of healthcare institution managers. Leadership in the healthcare sector is defined as the appropriate actions of a manager that enable change, create opportunities to foster employee motivation, and strengthen organizational commitment, thereby contributing to higher- quality healthcare services. It can be stated that the most critical factor is the manager's leadership style, interpreted as a combination of personal traits, skills, and behaviors aimed at influencing employees and enhancing their organizational commitment. In scientific literature, organizational commitment is regarded as an unequivocally positive factor that positively impacts operational efficiency and is associated with higher employee productivity, commitment, loyalty, and identification with the organization’s identity. By ensuring an appropriate leadership role in healthcare institutions, a positive influence on employee behavior is established, which leads to employees identifying with the organization and improving operational efficiency. This, in turn, facilitates the continuous delivery of professional and high-quality healthcare services. Considering this, it can be stated that this study is relevant; however, the context of personal healthcare institutions has not been extensively explored. The object of the study – the impact of manager’s leadership style on employees' organizational commitment. The aim of the study - to reveal the impact of manager’s leadership style on employees' organizational commitment in health care sector. Main results of the study. During the conducted research, it was found that the respondents among the managers of the healthcare sector most actively monitor the expression of the passive leadership style. During the research, it was identified that the general organizational commitment of employees among the respondents is below average, however, the emotional commitment dimension stood out as being rated higher than the overall construct of organizational commitment. When studying the influence of the manager's leadership style on the organizational commitment of employees, it was identified that the passive and transformational leadership style has a moderate positive influence on overall organizational commitment and only a weak positive influence on its dimensions
Factors influencing the organisational commitment of teleworkers.
No full textOrganisations are increasingly applying telework. For employees, teleworking is particularly attractive because of the time saved on commuting, increased productivity, work-life balance, flexibility, convenient scheduling (Longo, 2022), etc. Despite the benefits of teleworking, the loss of organisational attributes and direct communication with other members of the organisation makes it more difficult for teleworkers to maintain an important connection and identification with the organisation (Liu et al., 2022). The blurring of work-life boundaries and the distance between employees and the organisation hinders the establishment of valuable social ties, creating a sense of disconnection which has a negative impact on the commitment of teleworkers (Lott & Abendroth, 2023; Stranzl et al., 2024). Organisational commitment, as the binding force that connects the employee to the organisation, has been recognised by researchers as a crucial phenomenon for the success of organisations and one of the most important organisational variables directly or indirectly influencing many organisational outcomes (Đorđević et al., 2020). To date, research has mainly analysed the organisational commitment of employees working on workplace premises. As the number and use of teleworking forms in organisations increases, it is necessary to recognise that teleworking poses extraordinary challenges to employees' organisational commitment, and that the factors used to maintain or increase employees' commitment to the organisation in a teleworking form of organisation may differ. Thus, it is crucial to assess which factors may determine the commitment of teleworkers in particular
Training and applying artificial intelligence for the creation of original music.
No full textCurrent artificial intelligence (AI) tools for music creation are pre-trained using general datasets. As a result, AI models assimilate general principles of music creation, while the unique style of individual artists is not highlighted. This can lead to stylistic homogenization of compositions and raise copyright concerns. This issue is particularly relevant for creators seeking to integrate AI tools into their creative process while maintaining a distinctive sound. This study aims to investigate how to personalize the training of AI models with limited resources by using personal creative content, as well as how to creatively adapt existing tools trained on general data. This dual perspective seeks to provide creators with methods to effectively integrate AI tools into the creative process without losing originality and artistic authenticity. Research objective – the use of AI tools in the music creation process and the possibilities of training generative AI (GAI) with limited resources. Project goal – to explore the potential of AI in original music creation and to develop a simplified GAI training methodology for music creators without programming experience. Tasks: 1. Examine the possibilities offered by pre-trained AI for original music creation. 2. Analyze available GAI training options, considering existing resources (financial, technological, and knowledge-based). 3. Define the concept of original music in the context of AI. 4. Apply the analyzed pre-trained AI capabilities and identified tools to original music creation to test AI’s creative potential in practice. 5. Implement the analyzed GAI training options and tools for original music creation to test the creative possibilities of trained GAI in practice. An experiment was conducted using "Magenta" models ("MelodyRNN" and "MusicVAE") trained on personal compositions, as well as a Markov chain model through "Max for Live." Additionally, pre-trained AI tools such as "Suno" and "Udio" were employed, with their generated ideas creatively integrated into compositions. The results demonstrated that personalized AI models can generate new musical ideas while preserving the artist's style, however, they are less flexible than the most advanced AI music generators and pose technical challenges. Pre-trained models provide interesting interpretations, but their use limits control and raises copyright issues. This work highlights the potential and limitations of AI in the creative process, opening opportunities for new experiments, rhythms, and melodies while preserving artistic authenticity
Assessment of the impact of green transformation on the green competitiveness of Lithuania's packaging production sector.
No full textPackaging production is closely connected to various industrial sectors and significantly impacts them. Properly selected packaging facilitates the efficient transportation and storage of goods, reduces the risk of damage, optimizes logistics processes, and serves as a powerful marketing tool. However, packaging production is associated not only with high waste generation but also with significant resource usage. The goals of the green transformation—environmental protection, sustainable development, resource use reduction, and economic growth—form the foundation for strengthening green competitiveness. In this context, green competitiveness becomes a strategic tool that enables companies not only to respond to regulatory changes but also to improve long-term operational efficiency, reduce production costs, enhance customer loyalty, and meet societal expectations for responsible business practices. All these challenges encompass a fundamental dilemma: how to reconcile the development and increased attractiveness of Lithuania's packaging production sector with the goals of the green transformation. It can be stated that the topic of green competitiveness is becoming significantly relevant in both business and science, but still there are no studies that would define the evaluation of green competitiveness of the packaging production sector. Research problem: how to evaluate the impact of green transformation on the green competitiveness of Lithuania's packaging production sector. Research objective: to evaluate the impact of green transformation on competitiveness. Research process and results: the first part of the master’s final project describes the situation of Lithuania’s packaging production sector and reveals problematic aspects of green competitiveness in the sector. The second part analyzed scientific literature and examined how the concept of green competitiveness has developed and its interaction with the green transformation. The interactions between sustainability, durability, and frugality concepts were analyzed in the context of green transformation, alongside environmental regulatory barriers in Lithuania’s packaging sector, and the specifics of green competitiveness evaluation were explained. The third part outlined the methodology of the conducted research. The fourth part carried out statistical analysis to evaluate the relationship between green transformation indicators and Lithuania’s packaging sector performance indicators, as well as developed forecasting models. Econometric analysis revealed that, when examining the performance indicators of Lithuania’s packaging sector in regression with environmental indicators, increasing waste quantities positively impact the sector’s gross profit and turnover but negatively affect green competitiveness. When examining the sector’s performance indicators in regression with circularity indicators, it was found that increasing private investments and gross value added related to circular economy sectors positively affect and increase the green competitiveness of Lithuania’s packaging sector. However, an important aspect of the research is that the remaining green transformation indicators show no relationship with the sector’s performance indicators. This indicates that environmental and circular economy programs are often long-term, and their impact on indicators becomes noticeable only over time
The effect of bipolar charge transport of derivatives of 1-phenyl-1H-benzo[d]imidazole with horizontal molecular orientation on the performance of OLEDs based on thermally activated delayed fluorescence or phosphorescence /
No full textThe synthesis and properties of two derivatives of 1-phenyl-1H-benzo[d]imidazole with differing numbers of tert-butylcarbazole electron-donating moieties are reported. The compounds exhibit high thermal stability, with 5% weight loss temperatures exceeding 341 °C and glass transition temperatures of over 149 °C. They display moderate triplet energies of 2.63 and 2.66 eV. The synthesized compounds were employed as host materials in phosphorescence and TADF-based organic light-emitting diodes (OLEDs). An investigation of the angle-dependent emission intensity of light-emitting layers containing the phosphorescent emitter Ir(ppy)2(acac) doped into the examined compounds revealed a notably high internal outcoupling efficiency in OLEDs, exceeding 30%. This efficiency is attributed to the significant horizontal molecular orientation factor, reaching up to 87%. Based on the characterization of the hosting properties of 1-phenyl-1H-benzo[d]imidazole derivatives, the most significant influence on device performance is attributed to their charge-transporting properties. An OLED with the phosphorescent emitter Ir(ppy)2(acac) and a host material exhibiting bipolar charge transport demonstrated an external quantum efficiency of 13%. Additionally, the picric acid sensitivity of one of the compounds was examined. Triplet-facilitated emission was completely quenched upon the addition of a nitroaromatic explosive as a guest in a film
Software project risk identification based on scrum artifacts /
No full textRisk identification, as a foundational step in risk management, is essential for the success of software development projects, including those using the Scrum methodology. However, risk management in Scrum often lacks structured practices, relying instead on the iterative and collaborative nature of the methodology. This paper presents a novel risk identification framework tailored for Scrum projects, leveraging Scrum artifacts and their associated attributes to enhance risk detection and analysis. The framework encompasses automated data collection from project management environments, such as Jira, thus minimizing the effort required from the project team for risk-related data gathering. By monitoring deviations in artifact attributes and applying predefined thresholds, the framework facilitates the detection of risks at any point in the project lifecycle. Experimental evaluation across three distinct Scrum projects demonstrated the framework’s applicability in identifying a wide range of risks, including long-term ones. The proposed framework contributes to Agile project management by offering a structured, automated approach to risk identification, fostering a culture of proactive risk management within Scrum teams
Localized epoxy curing technology for enhanced aviation composite bonding /
No full textThe bonding process of composite materials in aerospace applications significantly impacts the structural integrity and energy efficiency of manufactured components. Traditional curing methods, such as oven and autoclave curing, are energy-intensive, costly, and unsuitable for handling large composite components, posing scalability challenges [1,2]. These methods often result in inefficient energy use due to the need for prolonged curing cycles and non-homogeneous heat distribution in the bonding areas [3,4]. This study explores an innovative bonding method using carbon nanotube (CNT)-enhanced epoxy adhesives, combined with localized Joule heating as an alternative to traditional curing methods. In this investigation, CNT-enhanced epoxy adhesives were applied exclusively to the bonding area of single-lap specimens reinforced with glass fibre-reinforced polymers (GFRP). CNT concentrations ranging from 0.25 to 1 wt% were evaluated. A resistive heating method enabled localized curing, with precise monitoring of temperature, electrical resistance, and thermal distribution across the bonding area. Mechanical performance of the bonded specimens was characterized by lap-shear testing in accordance with ISO 4587 standard. This localized curing approach has shown significant potential for enabling efficient adhesive polymerization while ensuring uniform heat distribution in the bonding area. Results indicate that optimal CNT concentrations (0.5 wt%) achieve a balance between thermal conductivity and mechanical strength, while higher concentrations lead to performance degradation due to agglomeration and void formation. This method offers a scalable, energy-efficient alternative for composite bonding, paving the way for advancements in aerospace manufacturing and other industries requiring high-performance composites