Tomas Bata University in Zlín
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Analysis of measurement uncertainties in mechanical production and subsequent use for process stability control
Get PDFIn the current industrial environment, where quality is a key factor in competitiveness, the measurement and control of the stability of production processes plays a vital role. This work focuses on the analysis of measurement uncertainties in mechanical production and their subsequent use for process stability control. Measurement uncertainties are an inherent part of any measurement system, and their understanding and proper management are necessary to ensure the accuracy and reliability of production processes. The MSA (Measurement Systems Analysis) method enables the assessment of the capability of measurement systems and the identification of sources of variability. Emphasis is placed on the standard uncertainties of types A and B and the ways in which they affect the measurement process. The work also includes a description of the implementation of statistical process control (SPC) and its importance in maintaining a stable production process. SPC makes it possible to continuously monitor production processes and quickly identify deviations, leading to timely corrections and minimization of defects. To achieve these goals, quality tools such as the Ishikawa diagram, histogram, and Pareto diagram are used. This work provides a comprehensive view of the importance of measurement and data analysis in ensuring stability and quality in manufacturing processes
Optimizing home heating: A numerical approach to assessing radiator, floor, and ceiling heaters
Get PDFThe paper presents a numerical assessment of various room heating methods using assembled room models. It compares the efficiency of floor heating, ceiling heating, and plane radiator heating in a selected room of a family house under winter conditions in the Central European climate zone. COMSOL Multiphysics software is used for computer simulations, and the output data are subsequently processed and analyzed using MATLAB software. Results indicate that floor and ceiling heating systems achieve higher and more rapid temperature increases compared to plane radiators. The distribution of air temperature within the room is also analyzed, revealing that floor heating provides the most uniform temperature distribution. These findings contribute to the development of effective heating strategies for residential buildings in similar climatic conditions. Furthermore, appropriate processing of output data obtained from computer simulations using artificial intelligence tools enhances the accuracy and efficiency of numerical analysis methods
Intellectual capital and firm performance: Evidence from certified firms from the EFQM excellence model
No full textThe main purpose of this study is to investigate the impacts of intellectual capital (IC) on the firm’s performance. Using a sample of 336 Czech firms, including 20 certified firms from the European Foundation for Quality Management (EFQM) Excellence Model from 2015 to 2019, the current study employed pooled regression to test the hypotheses. The dummy variable and dummy interaction terms are used to study the relationship between components of IC of certified firms from the EFQM Model with firm performance. Most of the significant results of the IC components of the certified firms and non-certified firms positively impact firm performance. The findings revealed that the quality certificate from the EFQM Excellence Model has a positive effect on the firm’s performance. The outcomes of the current study offer new and deeper insight into how each component of IC of the certified and non-certified firms relates to the firm’s performance.Internal Grant Agency; Tomas Bata University in Zlin, TBU, (IGA/FAME/2021/008); Tomas Bata University in Zlin, TBUInternal Grant Agency (IGA) in Tomas Bata University in Zlin, Czech Republic [IGA/FAME/2021/008
Antioxidant potential and its changes caused by various factors in lesser-known medicinal and aromatic plants
Get PDFThe review focuses on the evaluation of antioxidant potential and its changes by various factors such as growing conditions, the use of fertilizers, the analyzed part of the plant, the solvent used, the extraction method, purifying procedures, and the determination method for selected medicinal and aromatic plants that are lesser-known as antioxidant sources. The lesser-known representatives of Lamiaceae family (Lamium album, Leonurus cardiaca, Hyssopus officinalis, Scutellaria baicalensis), Asteraceae family (Artemisia absinthium), Myrtaceae family (Pimenta dioica), and Rosaceae family (Crataegus laevigata) were selected. The most important factors affecting antioxidant potential are the used solvent and its polarity (water and its temperature, ethanol, mixture of these solvents, methanol, n-butanol, and ethylacetate), extraction techniques, essential oil preparation, and the type and conditions of antioxidant activity (AA) determination method (DPPH, ABTS, FRAP, etc.). The plant composition and the occurrence of biologically active compounds (BACs), such as phenolics (phenolic acids and flavonoids) that participate in their biological impacts and deactivate reactive oxygen species, are also described. This work thus provides a summary of this issue and an extension of information focused on factors that affect plant components’ presence and thus have an impact on the overall antioxidant potential (total polyphenol content TPC, antioxidant activity) of lesser-known plant representatives with antioxidant effect
Ternary epoxy nanocomposites with synergistic effects: Preparation, properties evaluation and structure analysis
Get PDFThe objective of the present work was to prepare hybrid epoxy composites with improved mechanical and thermal properties. The simultaneous use of two different modifiers in an epoxy resin was motivated by the expected occurrence of synergistic effects on the performance properties of the matrix. Such a hybrid composite can be used in more severe conditions and/or in broader application areas. Hybrid epoxy composites were prepared with polyurethane (PUR), Nanomer nanoclay and carbon nanotubes (CNT), followed by the evaluation of their mechanical and thermal properties. Synergistic improvements in mechanical properties of hybrid composites were observed for 0.5 wt% Nanomer and 1 wt% carbon nanotubes (CNT), 7.5 wt% PUR and 1 wt% CNT, and 5 wt% PUR and 1 wt% CNT, confirming the occurrence of synergistic effects as to the impact strength (IS) of the matrices, compared to binary systems. The toughening induced by CNT/Nanomer modifiers can be attributed to the specific interfacial interactions between the two nanoparticles, while in the case of CNT/PUR, it can be explained by the combined effects of flexible polymer chains and the specific arrangement of nanoparticles in epoxy systems. Spectroscopy analysis confirmed the occurrence of interaction between OH groups in the epoxy matrix with CNT and reactive groups of PUR. The fracture surface showed plastic deformations, with good dispersion of CNT, explaining the improved mechanical properties of the matrix composites.Ministry of Education, Youth and Sports of the Czech Republic; [RP/CPS/2024-28/007
Ventilator-associated pneumonia in intensive care units: A comparison of pre-pandemic and COVID-19 periods
Get PDFBackground/Objectives: The COVID-19 pandemic has significantly increased the burden of ventilator-associated pneumonia (VAP) in intensive care units (ICUs) globally. However, epidemiological data on VAP in Slovak ICUs, particularly in the context of the pandemic, remain limited. This study aimed to evaluate the incidence, microbial profiles, and risk factors of VAP in Slovak ICU settings, particularly during the COVID-19 pandemic.
Methods: A retrospective analysis of VAP data was conducted for respiratory intensive care unit (ICU) patients in a Slovak university hospital, comparing data from the pre-pandemic and pandemic periods. The CDC/NHSN definitions for VAP were applied, and statistical analyses were performed using STATISTICA 13.1.
Results: A total of 803 patients were analyzed, representing 8385 bed days and 5836 mechanical ventilator days. VAP rates increased significantly during the pandemic by 111%, from 8.46 to 17.86 events per 1000 MV days (p < 0.001). VAP rates in non-COVID-19 patients increased by 86% during the pandemic compared to pre-pandemic levels. Pandemic conditions also increased ICU mortality from 25.66% to 40.52% (p < 0.001). VAP was identified as a critical determinant of ICU mortality, contributing to a 21.62% higher mortality rate among patients during the pandemic. Younger age, prolonged mechanical ventilation, and medical (vs. surgical) hospitalizations were associated with higher VAP incidence. Gram-negative bacteria dominated the pathogen profiles, with significant increases observed in Pseudomonas aeruginosa (183%), Klebsiella pneumoniae (150%), and Acinetobacter spp. (100%).
Conclusions: The COVID-19 pandemic has significantly affected the incidence and epidemiology of VAP in Slovak ICUs, highlighting systemic vulnerabilities in HAI surveillance and IPC practices.Catholic University in Ruzomberok [016 KU-4/2023
Molecular dynamics and experimental analysis of energy behavior during stress relaxation in magnetorheological elastomers
Get PDFThe diverse applications of magnetorheological elastomer (MRE) drive efforts to understand consistent performance and resistance to failure. Stress relaxation can lead to molecular chain deterioration, degradation in stiffness and rheological properties, and ultimately affect the life cycle of MRE. However, quantifying the energy and molecular dynamics during stress relaxation is challenging due to the difficulty of obtaining atomic-level insights experimentally. This study employs molecular dynamics (MD) simulation to elucidate the stress relaxation in MRE during constant strain. Magnetorheological elastomer models incorporating silicone rubber filled with varying magnetic iron particles (50–80 wt%) were constructed. Experimental results from an oscillatory shear rheometer showed the linear viscoelastic region of MRE to be within 0.001–0.01% strain. The simulation results indicated that stress relaxation has occurred, with stored energies decreased by 8.63–52.7% in all MRE models. Monitoring changes in energy components, the highest final stored energy (12,045 kJ) of the MRE model with 80 wt% Fe particles was primarily attributed to stronger intramolecular and intermolecular interactions, revealed by higher potential energy (3262 kJ) and van der Waals energy (− 2717.29 kJ). Stress relaxation also altered the molecular dynamics of this MRE model as evidenced by a decrease in kinetic energy (9362 kJ) and mean square displacement value (20,318 Å2). The MD simulation provides a promising quantitative tool for elucidating stress relaxation, preventing material failure and offering insights for the design of MRE in the nanotechnology industry.Universiti Teknologi Malaysia, UTM, (22H14); Professional Development Research University, (06E95); Grantová Agentura České Republiky, GAČR, (23-07244S)UTM Fundamental Research; Professional Development Research University (PDRU) [06E95]; Czech Science Foundation [23-07244S]; [22H14
Artificial intelligence and wealth inequality: A comprehensive empirical exploration of socioeconomic implications
No full textThis study introduces a global database on artificial intelligence (AI) capital stock and related AI indicators. Using the data constructed, we investigate the impact of AI and capital stock accumulation on wealth inequality, a dimension not extensively explored in the literature. This study contributes to the growing body of literature on the socioeconomic consequences of AI, with implications for scholars, policymakers, and corporate executives. An innovative database detailing AI capital stock is developed by incorporating data from various sources, including corporate reports, industry databases, and scholarly literature. This novel dataset, focusing on the US, the EU, and Japan from 1995 to 2020, is a critical resource for future investigations. The research methodology is centered on an extended Solow–Swan model, conceptualizing AI as a form of capital that can substitute for or complement traditional forms of labor. A panel-corrected standard errors model is used to analyze the data, accounting for potential cross-sectional dependence and heteroscedasticity. Our findings reveal a positive and statistically significant correlation between AI technology adoption, AI capital stock accumulation, and wealth disparity. The analysis further indicates a complex interaction between income and wealth disparities, suggesting a mutually reinforcing cycle. This study fills a significant gap in the existing literature by offering a novel perspective on the distributional impact of AI. Our results underscore the importance of considering the broader socioeconomic implications of AI, extending beyond considerations of immediate productivity and economic growth. This study offers valuable insights for policy formulation and business decision making, emphasizing the necessity of a comprehensive understanding of the influence of AI on wealth distribution
Electromagnetic modulation of conductance and susceptance in electrical devices based on silicone oil with polypyrrole-magnetite particle composites
No full textThis study investigates the fabrication and characterization of innovative electrical devices (EDs) subjected to an alternating electric field in the presence of static electric and magnetic fields. The EDs contain suspensions of silicone oil (SO) and micrometric aggregates of polypyrrole nanotubes decorated with various mass fractions of magnetite nanoparticles (PPyM). Our experimental findings and theoretical analyses demonstrate that the conductance and susceptance of these EDs can be coarsely adjusted by altering the mass ratios of magnetite to polypyrrole. Fine control of these electrical properties is achieved through the application of electric and magnetic fields superimposed on the alternating electric field. The findings reveal the dual responsiveness of the EDs at small values of electric and magnetic field intensities. A theoretical model is proposed that provides a qualitative description of the physical mechanisms governing the behavior of the EDs under these field conditions. Thus, the results contribute to advancing the understanding of electromagnetorheological phenomena at the microscale in this type of ED, highlighting the potential of PPyM composites dispersed within an SO matrix, in the development of sophisticated micromachines with dynamically controllable features under varying external conditions. Electrical conductance and susceptance of electrical devices with composite liquids based on silicone oil and polypyrrole-magnetite particles are finely tuned by varying electric and magnetic fields and adjusting magnetite content.Czech Science Foundation [23-07244S]Czech Science Foundation, (23-07244S
Quality evaluation of chicken liver pâté affected by algal hydrocolloids addition: A textural and rheological approach
Get PDFSimple Summary: Chicken liver pate is a smooth and spreadable product made from chicken meat, chicken livers, fat, seasoning and other optional ingredients (such as hydrocolloids). Hydrocolloids (polysaccharides or proteins) are commonly used in spreadable meat/poultry products (such as chicken liver pâté) to improve texture, stability and moisture retention, resulting in a product with desired functional and organoleptic properties. In general, the chicken liver pâté samples showed their highest hardness and viscoelastic moduli values when kappa-carrageenan and furcellaran were used. Suggestions for producing a softer chicken liver pâté consistency involve utilizing iota-carrageenan at a level between 0.25% and 0.75% (w/w) or furcellaran at a 0.25% w/w concentration. We can conclude that the use of hydrocolloids in the manufacturing of chicken liver pâté could be an effective solution leading to the development of products with desired techno-functional properties.
Hydrocolloids are used in spreadable meat or poultry products to improve consistency, emulsion stability and water retention, resulting in products with desired functional and organoleptic properties. The scope of the work was to evaluate the addition of three divergent algal hydrocolloids (kappa-carrageenan, iota-carrageenan, furcellaran) at four different concentrations (0.25, 0.50, 0.75, and 1.00% w/w) on the physicochemical, textural, rheological and organoleptic properties of model chicken liver pâté (CLP) samples. Overall, the highest hardness and viscoelastic moduli values of the CLP samples were reported when kappa-carrageenan and furcellaran were utilized at a concentration of 0.75% w/w (p < 0.05). Furthermore, increasing the concentrations of the utilized hydrocolloids led to increase in the viscoelastic moduli and hardness values of CLP. Compared to the control sample, an increase in spreadability was reported in the CLP samples with the addition of hydrocolloids. Finally, the use of algal hydrocolloids proved to be an effective way to modify the techno-functional properties of CLP.Ministry of Defence of the Czech Republic; Army of the Czech Republi