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Improvement of efficiency of industrial water cooling system.
No full textIn industrial facilities, water-cooling systems represent an energy intensive part of the infrastructure. Large volumes of recirculated water, fluctuating heat loads, and outdated equipment lead to high electricity consumption. With rising energy prices and stricter environmental requirements, assessing modernization options and identifying effective energy saving solutions has become essential. The study aimed to evaluate how the efficiency of an industrial water-cooling system could be improved by analysing technical upgrades, control strategies, and economic factors. The key problem was that traditional fixed-speed pump systems do not respond to real production load variations, causing excessive energy use and hydraulic losses. The research plan included several stages – analysing the efficiency of pumps used in industry and the applicability of variable-frequency drives, developing a numerical model of the existing cooling system using real operating data and enhancing the model with more efficient pumps and variable speed drives to determine the impact on hydraulics and energy use. An economic evaluation was then performed to estimate potential savings and payback time. The results showed that combining new pumps with variable speed drives significantly reduces electricity consumption across all operating modes: low-flow, medium-flow, and high-flow conditions. Modelling also revealed reduced pressure fluctuations, improved hydraulic stability, and pump efficiency consistently above 85% in the upgraded configuration. The economic analysis indicated that modernization could lower annual energy costs, with a payback period of roughly 2.5 years. Moreover, the modernized system would reduce CO2 emissions, supporting both corporate and national environmental goals. Additionally, based on the research results, conclusions and recommendations were provided to guide the modernization and efficiency improvement of the systems. Overall, the study demonstrates that integrating hydraulic improvements with advanced control solutions provides a strong foundation for long-term energy efficiency, lower operating costs, and more sustainable industrial development
Comprehensive modeling of CO2 sequestration in syderiai deep saline aquifer: insights into leakage, geo-mechanical changes, and geo-chemical impacts /
No full textThis paper presents a comprehensive study on the feasibility and implications of a CO2 injection simulation in the Syderiai deep saline aquifer of Lithuania, focusing on leakage, geo-mechanical aspects, and geo-chemical aspects. The Syderiai aquifer, characterized by its sandstone formation covered by shaly rocks, is considered a potential site for CO2 geological storage in Lithuania. Using 3D mechanistic models developed in T-navigator software, we conducted extensive simulations to analyze CO2 storage behavior and associated impacts. The leakage study examines various scenarios to assess the impact of fracture permeability, layer-wise heterogeneity, and fracture position on CO2 injection and leakage volumes. Results indicate that while fracture permeability influences CO2 migration dynamics, its impact on both free and dissolved CO2 leakage volumes is minimal, highlighting that leakage behavior is more dependent on the presence of fractures than their permeability. Geo-mechanical analysis reveals the effects of CO2 injection on the bulk modulus and shear modulus of sandstone and shale formations, highlighting changes in compaction and cementation. The geo-chemical study was performed using TOUGHREACT software V4.13-OMP to investigate the distribution of pH, porosity change, and free CO2 over 1000-years following 10-year CO2 injection. Results demonstrate the acidifying effect of CO2 injection and its implications for the caprock–reservoir interface over time. The findings offer valuable perspectives on the feasibility and consequences of CO2 geological storage in the Syderiai deep saline aquifer, highlighting the importance of incorporating leakage, geo-mechanical aspects, and geo-chemical aspects for implementing efficient CO2 storage
Development of 3D-printable lead-free composite materials for mixed photon and neutron attenuation /
No full textThe growing use of radiation technologies has increased the need for shielding materials that are lightweight, safe, and adaptable to complex geometries. While lead remains highly effective, its toxicity and weight limit its suitability, driving interest in alternative materials. The process of 3D printing enables the rapid fabrication of customized shielding geometries; however, only limited research has focused on 3D-printed polymer composites formulated specifically for mixed photon–neutron fields. In this study, we developed a series of 3D-printable ABS-based composites incorporating tungsten (W), bismuth oxide (Bi2O3), gadolinium oxide (Gd2O3), and boron nitride (BN). Composite filaments were produced using a controlled extrusion process, and all materials were 3D printed under identical conditions to enable consistent comparison across formulations. Photon attenuation at 120 kVp and neutron attenuation using a broad-spectrum Pu–Be source (activity 4.5 × 107 n/s), providing a mixed neutron field with a central flux of ~7 × 104 n·cm−2·s−1 (predominantly thermal with epithermal and fast components), were evaluated for both individual composite samples and layered (sandwich) configurations. Among single-material prints, the 30 wt% Bi2O3 composite achieved a mass attenuation coefficient of 2.30 cm2/g, approximately 68% of that of lead. Layered structures combining high-Z and neutron-absorbing fillers further improved performance, achieving up to ~95% attenuation of diagnostic X-rays and ~40% attenuation of neutrons. The developed materials provided a promising balance between 3D-printability and dual-field shielding effectiveness, highlighting their potential as lightweight, lead-free shielding components for diverse applications
Comparative analysis of the effectiveness of window-wall linear thermal bridges.
No full textGlobal warming is having an increasing impact on the environment and on the energy, construction, and other sectors, making the energy consumption of buildings one of the most important factors in reducing negative consequences for the environment and the economy. Since buildings account for a significant proportion of total energy consumption, particularly in the areas of heating and cooling, it is necessary to strive for greater energy efficiency. In response to the climate crisis, the European Union has introduced the European Green Deal, which aims to make the EU a climate-neutral region. Approximatly three-quarters of buildings use energy inefficiently and wastefully. Controlling and optimizing energy demand is therefore one of the most important measures enabling that will enable the European Union to influence the global energy market. The objective of this study is to perform a comparative analysis of the effectiveness of window-wall linear thermal bridges. Tasks: 1. To analyze publications by Lithuanian and foreign researchers, as well as and regulatory requirements related to window-wall thermal bridges. 2. To present the COPRAS multi-criteria evaluation algorithm and describe the tools and methods used in the study. 3. To investigate the longitudinal thermal bridges of three different window installation methods in walls, assess their impact on the energy efficiency of buildings, to determine the most effective window installation location in relation to the wall, and to select the most rational window installation system option using the COPRAS evaluation method. The first part of the master's thesis presents a review of scientific literature, which demonstrates that, in the context of climate change and considering the impact of buildings on energy consumption, it is particularly important to improve the energy efficiency of buildings, thereby reducing their environmental impact. The second part describes the methodology for calculating longitudinal thermal bridges and thermal resistance, and examines and describes the COPRAS multi-criteria evaluation method. The third part of thesis investigates three different window installation methods, evaluates six possible window installation locations, and determines the most effective wall-window installation solution. The evaluation criteria include the value of the longitudinal thermal bridge, thermal energy demand for heating and cooling the building, the CO2 emissions of the building, and the complexity of installing the wall-window junction. The master‘s thesis consists of: a summary in Lithuanian and English, three chapters, conclusions, a list of references and appendices. The project is 74 pages long, with a 3-page appendix. The list of references consists of 50 sources
The attractiveness of a maritime higher education institution as an employer.
No full textAs the maritime sector undergoes rapid transformation driven by technological advancements, the growing global demand for qualified seafarers highlights a strategic challenge for maritime higher education institutions: attracting and retaining competent academic staff. The employer attractiveness of these institutions is a key factor in securing personnel who possess both pedagogical competencies and practical seafaring experience. While the concept of employer attractiveness has been explored in various fields, it remains under-researched in the context of maritime higher education. Research aim – to reveal the employer attractiveness of maritime higher education institutions. Research objectives: 1. To define the genesis, concept, and dimensions of employer attractiveness and compare them with related constructs. 2. To describe the employer attractiveness of maritime higher education institutions, with emphasis on “interwoven careers” and positive intentions. 3. To develop a methodology for assessing the employer attractiveness of maritime higher education institutions. 4. To identify the key factors influencing the employer attractiveness of these institutions. To understand what constitutes employer attractiveness in maritime higher education and how it relates to employee behavior, a systematic literature review was conducted. Based on this, eight dimensions of employer attractiveness were identified: economic, social, developmental, practical (applied), interest-related, academic freedom, psychological (emotional), and reputational. These dimensions provide a conceptual framework to assess how employees perceive the attractiveness of an institution and how it influences their intention to engage or remain within it. A theoretical model was developed linking perceived employer attractiveness with employees’ positive intentions toward the organization. The empirical part involved a quantitative survey using a structured questionnaire. The study included 224 respondents comprising academic personnel and seafarers. The data were analyzed using descriptive, rank-based, correlational, and regression analyses. Results revealed that academic employees rated employer attractiveness higher than seafarers, with reputational, psychological, and social dimensions emerging as most influential. Statistically significant differences were found in how attractiveness and positive intentions were evaluated across demographic and professional groups. Moreover, a strong and statistically significant relationship was established between perceived employer attractiveness and employees’ positive intentions toward the organization. The findings allow for the formulation of practical recommendations for maritime higher education institutions seeking to strengthen their employer brand, especially by addressing the needs and motivational drivers of different employee segments
The relationship between empathetic leadership and employee commitment in educational institutions.
No full textIn the contemporary knowledge society, organizational success is increasingly determined by human resources, particularly employees’ intrinsic motivation, engagement, and commitment to the organization. In educational institutions, these aspects are especially important, as teachers and administrative staff have a direct impact on the quality of education, students’ academic achievement, and the development of institutional culture. Increasing workload, continuous changes in the education system, and emotional exhaustion weaken employees’ emotional attachment to educational institutions; therefore, strengthening employee commitment has become a strategic objective for these organizations. In academic literature, empathetic leadership – based on understanding employees’ emotional needs, respectful listening, and the creation of psychological safety – is identified as a significant factor capable of strengthening employees’ emotional connection with the organization. The relationship between empathetic leadership and employee commitment in educational institutions is therefore relevant and requires further in-depth analysis in order to better understand the role of empathetic leadership in fostering employees’ emotional commitment to the organization
Investigation on the effect of sawdust treated with special mineral additives on the physical and mechanical properties of cementitious composites.
No full textThis Master’s thesis investigates the properties of novel cement – sawdust composites in which wood sawdust is treated with special mineral additives. The topic is relevant in the context of increasingly stringent sustainability requirements in construction, the growing demand for renewable materials, and the objective of reducing the negative environmental impact of the construction sector. The aim of the thesis is to examine how the pre – treatment of wood sawdust affects the physical and mechanical properties of cement-based composite materials and to compare three different chemical treatment methods for wood particles. The objectives of the study are: to determine the influence of wood sawdust treatment on the mechanical properties of the composite; to evaluate how these treatments affect the water absorption properties of the composite; to identify which composite specimen exhibits the best thermal conductivity properties; and to compare the amount of CO₂ emissions generated during the production process of the composite. The research includes a literature review to identify the negative environmental impact of cement-based materials and to define the properties of cement – wood sawdust composites, as well as to assess how chemical treatment of wood sawdust influences composite performance. Experimental investigations are conducted to determine the density, compressive strength, flexural strength, water absorption, and thermal conductivity of the formed cement composites containing mineral – additive – treated wood sawdust, and to calculate their CO₂ footprint. All tests are carried out in accordance with LST EN standards. A comparison of the experimental results shows that treatment of wood sawdust with special mineral additives significantly affects the properties of the composite. However, the strength of the control mixture was not achieved. The best mechanical properties were obtained in specimens treated with a combination of sodium hydroxide, calcium hydroxide, silicon dioxide, and metakaolin, resulting in approximately 46% higher compressive strength, about 17% higher flexural strength, and around 36% lower water absorption compared to other mineral additive treatment combinations. The best thermal conductivity was achieved by specimens treated with a combination of sodium silicate and phosphogypsum, reaching 0,185 W/mK. These results demonstrate that cement composites incorporating chemically treated wood sawdust can be a competitive alternative to less environmentally friendly products currently available on the market
The impact of international economic sanctions on national economic growth.
No full textOver the past decades, international economic sanctions have become one of the most frequently used instruments of foreign and security policy, allowing states to restrict the activities of other countries, companies, or individuals without resorting to direct military intervention. Nevertheless, the economic consequences of sanctions affect not only the targeted entities but also the sanctioning states themselves, which incur adjustment costs due to changes in the volume and structure of foreign trade, investment and capital flows, financing conditions, energy and raw material price dynamics, and the costs of ensuring sanctions compliance and enforcement. Academic literature highlights that the majority of empirical research has traditionally focused on sanctioned states, while the economic costs borne by sanctioning countries have been assessed in a fragmented and inconsistent manner. In 2022, following Russia’s full-scale invasion of Ukraine, the tightening of the sanction’s regime imposed by European countries on Russia and Belarus further underscored the importance of systematically evaluating the economic effects such restrictive measures have on the sanctioning economies themselves. The aim of this master’s thesis is to evaluate the impact of international economic sanctions against Russia and Belarus on the economic growth of European states that imposed them, with particular attention to the tightening of sanctions in 2022. The thesis analyzes the impact of sanctions on the reconfiguration of trade flows, investment and foreign direct investment (FDI) dynamics, changes in financing conditions, and energy vulnerability. In the empirical section, panel-data fixed-effects and Difference-in-Differences (DiD) models are applied, using annual data for 2016–2024 for a sample of 60 countries (31 European sanctioning states and a control group of 29 countries). The econometric analysis shows that after the tightening of the sanctions regime in 2022, the real GDP growth rate in European states imposing sanctions on Russia and Belarus decreased in a statistically significant manner – by an average of about 1.47 percentage points (compared to the control group). The study revealed heterogeneity in the impact: the higher a country’s export dependence on the Russian and Belarusian markets prior to the sanctions, the more economic growth slowed – an additional 1 percentage point of dependence is associated with an approximately 0.44 percentage point greater deceleration of real GDP growth during the sanctions period. With respect to energy vulnerability, no significant systematic differences between countries were identified. The results suggest that the tightening of the sanctions regime in 2022 had a negative short-term impact on the economies of European countries imposing sanctions. A higher risk of negative effects was characteristic of countries with greater trade dependence on the Russian and Belarusian markets
Corrosion risk assessment of reinforced pile foundations under chemically active groundwater conditions.
No full textThe objective of this Master's thesis is to determine the effectiveness of different concrete admixtures in reinforced concrete structures exposed to a chloride-rich environment, utilizing both non-destructive and destructive testing methods. The Master's thesis is divided into three parts: a literature review, the methodology for the planned research, and the experimental results with conclusions. The literature review section examines various methods for determining the risk and rate of corrosion in reinforced concrete elements, as well as the influence of different chemically active environments on reinforced concrete structures. The research methodology section describes the tests and experiments planned during the course of the work, their procedures, and the instruments and principles by which the experiments will be conducted. The experimental results are described in the final section, where it was determined that the organic admixture is an ineffective additive for underground reinforced concrete structures exposed to chlorides. The research also demonstrated the effectiveness of the crystalline waterproofing admixture in saline and aqueous environments
Comparative study of family firms in Taiwan, Latvia, Lithuania. Dynamic managerial capabilities, organizational resilience, and succession practices :
No full textThis recommendation document presents both key research insights and practical guidelines for family businesses based on an international research project conducted in Lithuania, Latvia, and Taiwan. An international research team carried out 18 in-depth case studies—six in each country—focusing on family firms operating in the production, retail, and wholesale sectors. The study explored three major themes: dynamic managerial capabilities, organizational resilience, and succession planning and generational transition, offering evidence-based recommendations to support the sustainable development of family firms