Lublin University of Technology Journals
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Konstrukcja i technologia szybowca SZD-51-1 Junior
Full text linkThe article discusses selected issues of gliders constructed using glass-epoxy composite technology. The basics of the technology of these composites are presented, detailing the essential materials and production methods. The design of the SZD-51-1 Junior glider is presented, which is an example of an aircraft constructed and manufactured using the technology in question.Artykuł omawia wybrane zagadnienia szybowców konstruowanych z wykorzystaniem technologii kompozytów szklano-epoksydowych. Przedstawiono podstawy technologii tych kompozytów z wyszczególnieniem zasadniczych materiałów oraz metod produkcyjnych. Zaprezentowano konstrukcję szybowca SZD-51-1 Junior, który stanowi przykład statku powietrznego skonstruowanego i produkowanego w oparciu o przedmiotową technologię
Durability assessment of bio-based self-compacting sand concrete with recycled granite aggregate waste against chloride and sulphate attacks
Full text linkThe development of sustainable high-performance concrete with improved mechanical and durability properties while incorporating environmentally friendly components is a major concern today. This work investigates the feasibility of using granite industrial waste (GW) as a natural sand substitute by volume (10, 20, 30, and 40%) combined with seashell waste powder (SWP) as a cement substitute by weight (5, 10, and 15%) to improve the durability performance of self-compacting sand concrete (SCSC) against sulphate attack and chloride permeation. The obtained results showed the feasibility of developing eco-friendly SCSC by replacing up to 40% of sand with GW and 15% of cement with SWP, with a significant improvement in compressive strength and durability properties. However, SCSC containing 40% GW and 10% SWP showed the highest compressive strength (63 MPa), a 36.65% increase in electrical resistivity, and a 48.18% decrease in chloride-ion permeability. All SCSC mixes presented electrical resistivity greater than 20 kΩ·cm and chloride-ion passed charge below 2000 C, meeting the requirements for practical engineering applications. Furthermore, the response of the SCSC mix with GW and SWP against sulphate attack was considerably better than that of the control SCSC mix. Finally, the study results in the development of an encouraging and highly resistant concrete to extreme conditions without significant material damage, while reducing the demand for natural aggregates and conventional cement
The relationship between thermal insulation and heat source in shaping the energy efficiency of residential buildings: a case study of Poland
Full text linkThe energy efficiency of residential buildings results from the complex interplay of thermal insulation parameters of building envelopes, ventilation systems, and heat sources. This article examines these interdependencies in the context of reducing the EP (primary energy) index, considering the standards effective from 2021. The study highlights that improving the thermal insulation of external walls plays a pivotal role in lowering the EP index, surpassing the effects of roof or ground floor insulation. The findings reveal that the benefits of reducing the U-value vary depending on the heat source. The greatest savings were observed in buildings with electric heating, while buildings equipped with heat pumps showed limited benefits due to their high efficiency (COP). Furthermore, the application of mechanical ventilation improves a building’s energy performance, particularly when combined with traditional heat sources. In contrast, its impact is minimal in buildings with heat pumps. The results emphasise the importance of an integrated approach to building design, accounting for the interactions between envelope insulation, ventilation systems, and heat sources. It is recommended to optimise thermal parameters and invest in modern heating and ventilation technologies to achieve significant energy savings and meet stringent climate requirements.The energy efficiency of residential buildings results from the complex interplay of thermal insulation parameters of building envelopes, ventilation systems, and heat sources. This article examines these interdependencies in the context of reducing the EP (primary energy) index, considering the standards effective from 2021. The study highlights that improving the thermal insulation of external walls plays a pivotal role in lowering the EP index, surpassing the effects of roof or ground floor insulation. The findings reveal that the benefits of reducing the U-value vary depending on the heat source. The greatest savings were observed in buildings with electric heating, while buildings equipped with heat pumps showed limited benefits due to their high efficiency (COP). Furthermore, the application of mechanical ventilation improves a building’s energy performance, particularly when combined with traditional heat sources. In contrast, its impact is minimal in buildings with heat pumps. The results emphasise the importance of an integrated approach to building design, accounting for the interactions between envelope insulation, ventilation systems, and heat sources. It is recommended to optimise thermal parameters and invest in modern heating and ventilation technologies to achieve significant energy savings and meet stringent climate requirements
Opracowanie modelu analitycznego i metody optymalizacji priorytetowej obsługi korporacyjnej sieci komputerowej "Wybory"
Full text linkThe main objective of this article is to provide recommendations for improving the quality of service indicators in priority service corporate computer networks, including the probability of denial of service attacks, the probability of timely and lossless information delivery, and the selection and effective use of equipment that meets modern requirements.Głównym celem tego artykułu jest przedstawienie zaleceń dotyczących poprawy wskaźników jakości usług w korporacyjnych sieciach komputerowych z usługami priorytetowymi, w tym prawdopodobieństwa ataków typu "odmowa usługi", prawdopodobieństwa terminowego i bezstratnego dostarczania informacji oraz wyboru i efektywnego wykorzystania sprzętu spełniającego współczesne wymagania
Rozwój i optymalizacja urządzenia sterującego napędem hydraulicznym przenośnika taśmowego
Full text linkDesigning new hydraulic equipment requires consideration of the peculiarities of the operating modes of the technological machines. This particularly applies to the hydraulic drive of a belt conveyor, which operates under variable load conditions. Therefore, investigations aimed at reducing static and dynamic characteristic indicators, design calculations, as well as three-dimensional modelling, are relevant tasks for engineers and scientists. Various optimization methods for dynamic processes have been considered. Preference has been given to the linear programming method as the main one for optimizing dynamic processes in the hydraulic drive under overload conditions. Fundamental schemes of the belt conveyor hydraulic drive and control device have been developed and their principles of operation described. Nonlinear differential equations in Cauchy form have been formulated and solved using the MATLAB Simulink software package. A comprehensive criterion for optimizing the static and dynamic characteristics of the belt conveyor hydraulic drive has been developed. Graphs of dynamic processes before and after optimizing static and dynamic characteristics have been provided depending on the parameters of the control device construction. The minimum value of the comprehensive criterion optimization corresponding to rational parameters of the control device construction has been calculated. Based on these parameters, a three-dimensional model of the control device has been developed. The obtained research and calculations will be useful for engineers and scientists during the development and design of new hydraulic equipment.Projektowanie nowego sprzętu hydraulicznego wymaga uwzględnienia specyfiki trybów pracy maszyn technologicznych. Dotyczy to w szczególności napędu hydraulicznego przenośnika taśmowego, który pracuje w warunkach zmiennego obciążenia. Dlatego też badania mające na celu obniżenie wskaźników charakterystyk statycznych i dynamicznych, obliczenia projektowe, a także modelowanie trójwymiarowe stanowią istotne zadania dla inżynierów i naukowców. Rozważono różne metody optymalizacji procesów dynamicznych. Preferencję nadano metodzie programowania liniowego jako głównej metodzie optymalizacji procesów dynamicznych w napędzie hydraulicznym w warunkach przeciążenia. Opracowano podstawowe schematy napędu hydraulicznego przenośnika taśmowego i urządzenia sterującego oraz opisano ich zasady działania. Sformułowano i rozwiązano nieliniowe równania różniczkowe w postaci Cauchy'ego przy użyciu pakietu oprogramowania MATLAB Simulink. Opracowano kompleksowe kryterium optymalizacji charakterystyk statycznych i dynamicznych napędu hydraulicznego przenośnika taśmowego. Przedstawiono wykresy procesów dynamicznych przed i po optymalizacji charakterystyk statycznych i dynamicznych w zależności od parametrów konstrukcji urządzenia sterującego. Obliczono minimalną wartość kompleksowej optymalizacji kryterium odpowiadającej racjonalnym parametrom konstrukcji urządzenia sterującego. Na podstawie tych parametrów opracowano trójwymiarowy model urządzenia sterującego. Uzyskane badania i obliczenia będą przydatne dla inżynierów i naukowców podczas opracowywania i projektowania nowych urządzeń hydraulicznych
The impact of relational and non-relational databases on application performance
Full text linkThe purpose of this study was to assess the performance of two database systems, PostgreSQL (relational) and MongoDB (non-relational), in handling data and their impact on application performance. The evaluation was conducted through a series of performance tests including read, write, delete, update, and aggregation operations on small and large datasets. Key metrics such as task completion time, response times were used for comparisons. Based on the results obtained during the experiments, it is difficult to definitively conclude which database system performs better, as both systems demonstrated advantages in different scenarios depending on the specific use case
WThe Impact of Ecological Footprint, Energy Consumption and Economic Stability on Happiness: Evidence from BRICS-T Countries
No full textThe main objective of this study is to analyze the impact of ecological footprint, fossil fuel energy consumption, renewable energy consumption and economic stability on happiness in BRICS-T countries for the years between 2015-2022 with the help of methods that take into account cross-section dependence and also can be used for heterogeneous panels. In this context, Dynamic SUR and AMG estimators are used to determine whether there is a long-run relationship among the variables. As a results of the analysis, there is a difference for individual and panel results. The individual results show that the variables considered in the analysis are statistically significant and there are differences among countries. Also, panel results indicate that factors that increase environmental pollution, such as an increase in ecological footprint and fossil fuel energy consumption negatively affect happiness, while reducing environmental pollution like a rise in renewable energy consumption, and improvement in economic conditions, like an increase in economic stability increases happiness.Głównym celem niniejszego badania jest analiza wpływu śladu ekologicznego, zużycia energii z paliw kopalnych, zużycia energii odnawialnej i stabilności gospodarczej na szczęście w krajach BRICS-T w latach 2005-2023 za pomocą metod, które uwzględniają zależność przekrojową, a także mogą być stosowane do heterogenicznych paneli. W tym kontekście dynamiczne estymatory SUR i AMG zostały wykorzystywane do określenia, czy istnieje długoterminowy związek między zmiennymi. Wyniki analizy różnią się w przypadku wyników indywidualnych i panelowych. Wyniki indywidualne pokazują, że zmienne uwzględnione w analizie są statystycznie istotne i istnieją różnice między krajami. Ponadto wyniki panelowe wskazują, że czynniki zwiększające zanieczyszczenie środowiska, takie jak wzrost śladu ekologicznego i zużycie energii z paliw kopalnych, negatywnie wpływają na szczęście, podczas gdy zmniejszenie zanieczyszczenia środowiska, takie jak wzrost zużycia energii odnawialnej, oraz poprawa warunków ekonomicznych, takich jak wzrost stabilności gospodarczej, zwiększają poziom szczęścia
Carbon Footprints, Social Inclusion, and Inequality: Multidimensional Pathways to Sustainable Development Goals
Full text linkThis study investigates the multidimensional pathways to sustainable development by modelling three key Sustainable Development Goals (SDGs): SDG 13 (Climate Action), SDG 5 (Gender Equality), and SDG 10 (Reduced Inequality) as dependent variables. Drawing on Sustainable Development Theory, the study analyses the influence of carbon emissions, female labour force participation, social inclusion indicators (vulnerable employment and employment-to-population ratio), GDP per capita, urbanization, and the COVID-19 pandemic as explanatory variables. Using unbalanced panel data for 65 countries (27 Sub-Saharan African and 38 OECD countries) spanning 2000–2022, the study captures the structural and regional variations across income levels and development contexts. The SDG 13 model reveals that carbon emissions significantly hinder climate action in both regions, more severely in OECD countries. Urbanization promotes climate resilience in OECD nations, while it remains insignificant in SSA. GDP per capita shows a negative association with climate action in both regions, underlining the growth–sustainability trade-off. In the SDG 5 model, female labour force participation enhances gender equality outcomes in OECD countries but weakens them in SSA, where informal and subsistence employment dominate. For SDG 10, high levels of vulnerable employment undermine inequality reduction efforts in SSA, while in OECD countries, the employment-to-population ratio negatively correlates with inclusive progress, reflecting the complexity of job quality and equity. The pandemic temporarily improved environmental outcomes, but the effect was not sustained. The study contributes to the growing body of knowledge on sustainable development by offering regional insights into how socio-economic and environmental variables shape climate action, gender equality, and reduced inequality. It underscores the need for region-specific, integrative policies that address environmental sustainability, gender empowerment, and social inclusion concurrently to advance transformative progress across the SDGs.
 
Opracowanie i badanie parametrów W potencjalnie niestabilnych czwórników w oparciu o matematyczny model postaci W tranzystorów polowych w zakresie wysokich częstotliwości
Full text linkThe models underlying calculations and research provide the developers with information about the behavior of devices during operation. As modern technologies do not provide high accuracy of measurements, the unstructured models are used, in particular, four-poles, which describe electrical circuits through their external characteristics, without taking into account the internal structure. Four-pole parameters, such as conductivities and impedances, can be measured using special methods, which allows effective analysis of the electrical properties of devices and systems.Modele stanowiące podstawę obliczeń i badań dostarczają projektantom informacji na temat zachowania urządzeń podczas eksploatacji. Ponieważ współczesne technologie nie zapewniają wysokiej dokładności pomiarów, stosuje się modele bezstrukturalne, w szczególności czwórniki, które opisują schematy elektryczne poprzez ich charakterystykę zewnętrzną, bez uwzględnienia struktury wewnętrznej. Parametry czwórników, takie jak przewodność i impedancja, można zmierzyć za pomocą specjalnych metod, co pozwala skutecznie analizować właściwości elektryczne urządzeń i systemów
Comparative analysis of web and mobile interfaces of popular sales portals
Full text linkSales platforms are becoming increasingly popular, with a steadily growing user base. This article presents the results of a comparative study of the web and mobile interfaces of two popular sales platforms, OLX and Vinted, focusing on user efficiency and intuitiveness. The analysis entails measuring task completion times and evaluating the usability of both interface types on each platform using the System Usability Scale. The findings indicate that Vinted’s interface is more intuitive and faster for users who had no prior experience with OLX or Vinted