16168 research outputs found
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Virtual prototyping and CMT production for smart clothing /
No full textThe aim in this research is to utilize virtual prototyping to design and develop tightly fitting smart clothing integrated with transmission lines produced from conductive textiles using cut-and-sew technologies. The study evaluates how body posture dynamics affect the comfort and aesthetics of the garment by examining the tensile strain behavior of the element with conductive textile tracks. Virtual try-on technology was employed to assess garments with different geometry elements with conductive tracks. The results indicate that the sewn conductive tracks significantly limit the deformability of the basis material under low loads, and that up to four times less force is required to obtain 20% stretching deformations in systems incorporating Shieldex Balingen (SB), compared with those incorporating Shieldex Kassel (SK). The geometry of the element with conductive tracks is important for wear comfort during body movement, with simulations showing maximum deformations of up to 20% lengthening in the shoulder blade area. The best performance was observed in a variant 1 in which the SB conductive material extends 6 cm along the measurement line, with vertical tracks spaced 44 mm apart. Conductive element incorporating knitted fabric SB demonstrated good deformation properties, making it an excellent choice for tightly fitting smart clothing design. However, continued research and development is recommended to optimize these elements with transmission lines of conductive textiles, and further evaluation will be required to assess the durability and resistance to multicyclic stretching and washing
Enhancing mechanical and impact properties of flax/glass and jute/glass hybrid composites through KOH alkaline treatment /
No full textThis research investigates the influence of potassium hydroxide (KOH) treatment on the mechanical, flexural, and impact properties of flax/glass and jute/glass hybrid composites. Hybrid composite materials have been developed, incorporating natural fibers that are both treated and untreated by KOH, with glass fiber within an epoxy matrix. Natural fibers, such as flax and jute, were chemically treated using different KOH concentrations and immersion times specific to each fiber type. Following the treatment, both fibers were rinsed with distilled water and subsequently dried. The natural fiber’s chemical interaction was analysed using FTIR. Hybrid composites were fabricated via the integration of intercalated layers of natural fibers and glass fiber using hand layup followed by compression molding. Mechanical properties, including impact resistance, flexural strength, elastic modulus, and tensile strength, were evaluated in accordance with ASTM guidelines. KOH-treated flax/glass composites (T-F2G2) demonstrated enhanced fiber–matrix bonding, indicated by elevated tensile strength (118.16 MPa) and flexural strength (168.94 MPa) relative to untreated samples. The impact strength of T-F2G2 composites increased to 39.33 KJ/m2 due to the removal of impurities and exposure of hydroxyl groups, which interact with K+ ions in KOH, thereby improving their mechanical properties. SEM analysis of cracked surfaces confirmed enhanced bonding and reduced fiber pull-out, indicating improved interfacial compatibility. The findings demonstrate that KOH treatment effectively preserves cellulose integrity and enhances fiber–matrix interactions, positioning it as a viable alternative to NaOH for hybrid composites suitable for lightweight and environmentally sustainable industrial applications
Modeling forest regeneration dynamics: estimating regeneration, growth, and mortality rates in Lithuanian forests /
No full textThis study presents a novel approach to analyzing forest regeneration dynamics by integrating a Markov chain model with Multivariate Time Series (MTY) decomposition. The probabilistic tracking of age-class transitions was combined with the decomposition of regeneration rates into trend, seasonal, and irregular components, unlike traditional deterministic models, capturing the variability and uncertainties inherent in forest ecosystems, offering a more nuanced understanding of how Scots pine (Pinus sylvestris L.) and other tree species evolve under different management and climate scenarios. Using 20 years of empirical data from the Lithuanian National Forest Inventory, the study evaluates key growth and mortality parameters for Scots pine, Spruce (Picea abies), Birch (Betula pendula), and Aspen (Populus tremula). The model for Scots pine showed a 79.6% probability of advancing from the 1–10 age class to the 11–20 age class, with subsequent transitions of 82.9% and 84.1% for older age classes. The model for Birch shown a strong early growth rate, with an 84% chance of transitioning to the next age class, while the model for Aspen indicated strong slowdown after 31 years. The model indicated moderate early growth for Spruce with a high transition in later stages, highlighting its resilience in mature forest ecosystems. Sensitivity analysis revealed that while higher growth rates can prolong forest stand longevity, mortality rates above 0.33 severely compromise stand viability. The Hotelling (Formula presented.) control chart identified critical deviations in forest dynamics, particularly in years 13 and 19, suggesting periods of environmental stress. The model offers actionable insights for sustainable forest management, emphasizing the importance of species-specific strategies, adaptive interventions, and the integration of climate change resilience into long-term forest planning
Impact of age and mean intracranial pressure on the morphology of intracranial pressure waveform and its association with mortality in traumatic brain injury /
No full textEfficiency in building energy use: pattern discovery and crisis identification in hot-water consumption data /
No full textAs global challenges such as climate change and pandemics increasingly disrupt urban systems, the need for efficient and resilient management of energy resources has become critical. The energy used to prepare domestic hot water (DHW) takes a large proportion of residential buildings’ total thermal energy demand. However, it is often overlooked in research due to its stochastic nature and high dependence on user behaviour. This study explores the identification of the crisis and its severity level in the DHW consumption data and the corresponding control actions necessary to mitigate its impact. To identify crisis severity, we utilised the mobility data of retail/recreation activities and transit stations, making the results generalisable for any crisis. In addition, we used power consumption for DHW preparation data from 10 residential apartment buildings located in Kaunas city to develop a machine learning-based hybrid ensembling stacking classifier (ESC) capable of predicting the crisis and its severity level. Finally, we applied principal component analysis (PCA) and k-means clustering to categorise DHW consumption hours throughout the day for each severity level. The results showed that the developed ESC classifier significantly outperforms (2 = 0.99) the baseline LGBMC classifier (2 = 0.92). Combining the classifier with extracted daily consumption patterns and clusters allows the optimisation of control actions on the supply, distribution, and demand side of the DHW system
Fertilizers with organic additives /
No full textThe goal of this work is to address soil degradation by developing fertilizers enriched with organic bio-additives. Intensive agricultural practices contribute to the decline in soil organic matter, which is essential for maintaining soil health. Soil organic matter (SOM) influences key soil properties, including moisture retention, pH balance, nutrient availability, structure, and resistance to erosion. Additionally, SOM serves as an indicator of soil quality and is critical for the ecological stability of the biosphere. As SOM levels decline, soil properties deteriorate: aeration, water absorption, and structural stability decrease, while soil density and surface runoff increase, leading to erosion. Over time, when farming in this way for a longer period of time, the soil seems to die, and in order to maintain crop productivity, the use of mineral fertilizers and pesticides has to be increased. The chemical composition of banana peels was analyzed by employing methods of chemical analysis: the concentration of phosphorus (P2O5) was determined by using the photocolorimetrical method (T70/T80 UV–VIS); the concentration of potassium (K2O) was discovered by employing the marginal solutions method using the flame photometer “PFP–7.” [...]
Research and development of helicopter door gunnery trainer.
No full textIn this paper structural and technical performance characteristics of the FN MAG KSP – 58 medium machine gun, used by the Lithuanian military, were analyzed. An overview of the UH – 60 “Black Hawk” helicopter’s technical characteristics has been carried out. Various medium machine gun mounts for the helicopter door gunner have been examined. Looked into already existing door gunner trainers that don't use live ammunition, their working principles and advantages. Analysis of present forces and dynamic characteristics during shooting from a machine gun mount. After performing theoretical calculations, it was concluded that the training stand suppresses all weapon motions until it returns to its starting position. It was concluded, that one of the most important parts in gunnery training is the exact replication of the door gunner position and machine gun mount. It was concluded that the gunnery trainer must accurately replicate the helicopter machine gun mount, gunners position and field of view. Projected the training stand to be usable for both indoor training and outdoor shooting range exercises, able to mount a medium machine gun FN MAG KSP – 58 and a trainer weapon replicating it. This paper provides a concept for a helicopter door gunner training stand created using ,,Solidworks" software. Dynamic forces and virtual fatigue analysis of the training stand, which was created based on UH – 60 ,,Black Hawk" helicopter door gunner position parameters, firing from the medium machine gun FN MAG KSP - 58. Virtual structural strength analysis identified the stresses acting on the structure of the training stand and their location. During the virtual fatigue analysis, it was determined that after 1 000 000 shots, the training stand did not suffer any structural damage or permanent deformation. An experiment was performed to find recoil dynamic characteristics of single shot and burst firing medium machine gun FN MAG KSP – 58 when having the weapon mounted on the training stand and placed on the ground. Evaluated the size and difference in recoil kick while using different types of blank ammunition. During the experiment it was discovered that while the machine gun is mounted on the training stand, the shooter experiances approximately 10 N reduced recoil kick compared to firing with the weapon placed on the ground. It was discovered that blank rounds in plastic casings generate less force when fired compared to metal casings; therefore, the recoil force and rate of fire gets reduced
Development and research of a motorcyclist's helmet light.
No full textMotorcycles are a popular means of transport in traffic. They are affordable and easy to maintain. The number of motorcyclists in traffic is increasing every year, especially during the warm season. It can be used to accelerate quickly, reach high speeds and perform manoeuvres such as sudden lane changes or overtaking. However, such actions pose a threat and a risk of an accident for the rider of the motorcycle and for other road users around them. The visibility of the motorcycle is another reason why accidents occur. Motorcycles do not have large dimensions compared to cars or lorries. The size of the motorcycle determines the number and size of the lights, making it difficult to see when the rider is braking or making a turning manoeuvre. Although the majority of accidents between motorcycles and other vehicles are head-on collisions, rear-end collisions are unavoidable. Transport authorities warn motorcyclists to watch out for motorcyclists by checking their blind spots and keeping a greater distance between riders. Authorities also recommend wearing brighter colours to be more visible in traffic. Helmet lights are available on the market, but the choice is limited and not all lights are chosen to include brake, left and right turn signals. The aim of this work is to develop a model of a motorcycle helmet lamp and to investigate the possible illuminance of the lamp
Contemporary hotel for students and lecturers in Kaunas old town 15 quarter.
No full textA hotel for students and lecturers is being designed in the 15th quarter of Kaunas Old Town on an empty plot. Development on this plot existed until the mid-20th century. The aim of this project is to design a modern type of hotel for students and lecturers on the planned site. The analytical paper analyzed various types of hotels and sought conclusions about what kind of hotel could meet the needs of students and lecturers, considering its function and compliance. The conclusions focus on the design of a modern co-living hotel for students and lecturers in the heart of Kaunas Old Town. The research also formulates five hypotheses based on a hypothetical model and identifies key directions to be explored in the empirical research stage. These directions include functional aspects of the building, needs in specific location, architectural design aspects, and social aspects. The following empirical research in this paper focuses on analyzing the factors contributing to the popularity and efficiency of modern hotels in Lithuania, particularly in Kaunas’ Old Town. The research aims to understand how a modern building can functionally and visually reflect the current era while preserving and enhancing the historical cultural heritage. The research employed a combination of empirical research, qualitative and quantitative analyses, statistical data analysis, and GIS location analysis to identify key factors influencing the popularity and efficiency of modern hotels. Each method complemented the others, providing a more focused and relevant empirical research process. All hypotheses were confirmed, and useful information was gathered, from all analyses, a conceptual model is created for the next experimental project step. The last stage involved a comprehensive site analysis. The 15th block is part of Kaunas Old Town's national heritage and contains several valuable assets. The analysis also included transportation, pedestrian and cycling paths, green areas, and flood risk within the overall context of the Old Town, diving deeper into block analysis and eventually touching on the evaluation of cultural heritage objects. Following the analyses, two experimental projects were developed to test architectural solutions for a hotel based on the findings from the analytical and empirical research phases. These projects highlighted different aspects of the conceptual model: one focusing on integrating open and inclusive city functional zones and the other on revitalizing a deteriorating cultural heritage site. The second project was selected as the most optimal and suitable for further development. The project combines elements of old and new architecture to create a closed-type hotel with 50 apartments. The design focuses on user comfort, sustainability, and contextual harmony, incorporating features like a pitched roof, green solutions, and wooden structures. The historical building is integrated through a glass corridor that maximally respects and preserves the history of its era. The study emphasizes the interaction between theory and practice, exploring heritage preservation, as well as social and functional aspects of co-living hotels. It highlights the long- term architectural value, sustainable development, and the potential for further scientific analysis in an international context
Investigation of robotized incremental composite sheet forming.
No full textWith the rapid expansion of manufacturing technologies, there is a growing demand for composite materials that are not only mechanically strong but also possess additional functional properties such as electrical conductivity, flexibility and formability. One such direction is the development of graphene-reinforced TPC, intended for 3D printing and subsequent robotic incremental forming. The main objective of this study was to evaluate the behavior of TPC material enhanced with graphene (from 4% to 8%) under deformation, assess its mechanical properties, and determine suitable forming parameters. During experimental investigations, tensile (ISO 527-3), electrical conductivity (ISO 3915), and cupping (ISO 20482) tests were performed to evaluate the properties of TPC/Gr composites with different graphene concentrations. The tensile test results showed that increasing the graphene content up to 8% significantly improved tensile strength and shear modulus, while reducing the strain at break, indicating decreased elasticity. Electrical conductivity tests revealed that higher graphene content improved conductivity – the lowest resistance values were recorded for the TPC/Gr-8% [-45°/45°] structure. However, the TPC/Gr-5% [-45°/45°] structure was selected as the optimal composition due to its stable conductivity under deformation and well-balanced mechanical performance. Cupping test results indicated that increasing graphene content enhanced mechanical resistance, but reduced the material’s ability to deform without failure. The pure TPC sample (without fillers) demonstrated the greatest indentation depth, while the TPC/Gr-8% [-45°/45°] structure showed the least. The TPC/Gr-5% [-45°/45°] structure ranked in between, showing sufficient resistance and deformation capability, thus being considered the most suitable for further forming experiments. In robotic incremental sheet forming trials, the TPC/Gr-5% [-45°/45°] structure was subjected to different temperatures to identify optimal processing conditions. The results showed that at 270-280 °C, deformation was uniform, the surface remained intact and the forming process was stable and free from structural defects. In contrast, at lower temperatures (240-250 °C), microcracks and surface imperfections were observed, which reduced structural integrity and reliability. Numerical analysis using the finite element method was conducted to assess the behavior of the TPC/Gr-5% [-45°/45°] structure during cupping and robotic incremental sheet forming forming. After updating the material model parameters based on experimental data, the computed load and deformation values closely matched those obtained experimentally: the stress and indentation depth from cupping differed by less than 2%, and the forming force deviation did not exceed 8%. These findings confirm the numerical model’s suitability for predicting real-world forming processes and its applicability for further process optimization