Tomas Bata University in Zlín
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Experimental study on the effect of inverted aperture plate temperature on frosting characteristics under rising flow considering edge effect
No full textTo reduce the negative impact of frost formation on cold surfaces in low-temperature environments, metal wire mesh can be set in the air flow direction from the cold surface to reduce air humidity. To quantitatively determine the effectiveness of dehumidification after passing through a metal wire, the frosting process needs to be studied. To analyze the mechanism of frost formation under the horizontal wire mesh surface, the wire mesh was simplified as a flat plate with holes, or aperture plate, with plate temperature varying at a range of -15.0 °C to -5.0 °C. The results show that, as the plate temperature decreases, the droplet condensation and growth and droplet solidification stages gradually decrease, the average frost layer thickness and frost layer growth rate rise, and overall frost layer surface roughness increases. For a frosting duration of 1,800 s, compared to -5.0 °C, the average frost layer thickness from -7.5 °C to -15.0 °C inside the hole increased by 56.68 % and 156.41 %, while the plate edge region away from the hole increased by 40.76 % and 169.92 %, respectively. The reverse melting frequency gap between the inside hole region and the plate edge region away from the hole increases with the decreasing aperture plate temperature. At -15.0 °C, the reverse melting frequency inside the hole is 5.00 × 10−3 Hz lower than in the region of the plate edge away from the hole. The results of this article are beneficial for understanding the frosting process of wire mesh or perforated-fin heat exchanger.Ministry of Science and ICT of the Republic of Korea; National Natural Science Foundation of China, NSFC, (52076013); Ministry of Science and Technology of the People's Republic of China, MOST; National Research Foundation of Korea, NRF; Beijing Municipal Science and Technology Commission, Adminitrative Commission of Zhongguancun Science Park, (3212024)National Natural Science Foundation of China [52076013]; Beijing Municipal Science & Technology Commission [3212024]; China -South Korea Youth Scientists Exchange Program in 2023 - Ministry of Science and Technology of China; Ministry of Science and ICT of the Republic of Korea; National Research Foundation of Kore
Motivations underlying healthy dietary adoption intentions: Evidence from university students in the Czech Republic
Get PDFEncouraging people to adopt a healthy diet is believed to reduce the prevalence of obesity. However, a deeper understanding of consumers' psychology regarding healthy dieting is required for this intervention to be effective. To date, knowledge remains limited on the motivations preceding healthy dietary adoption among adult consumers in the Czech Republic, which is undoubtedly facing a high prevalence of obesity among other EU member states. Most importantly, few studies have modeled the food choice motives as primary antecedents of healthy dietary adoption intentions. Therefore, the current study proposes and tests a research model that explains the motivational factors for adopting healthy diets. Data were collected through an online survey involving 161 university students and analyzed using partial least squares structural equation modeling (PLS-SEM) procedures. The results reveal that food choice motives explain healthy dietary adoption intentions satisfactorily. Notably, the natural content and weight control motives positively and significantly affect healthy dietary adoption intentions. The study offers relevant contributions to the science of consumer motivation regarding healthy dieting and practical means to health promotion.Univerzita Tomáše Bati ve Zlíně, UTB, (CZ.02.2.69/0.0/0.0/19_073/0016941
Optimization of CoFe2O4 nanoparticles and graphite fillers to endow thermoplastic polyurethane nanocomposites with superior electromagnetic interference shielding performance
No full textThe rapid growth, integration, and miniaturization of electronics have raised significant concerns about how to handle issues with electromagnetic interference (EMI), which has increased demand for the creation of EMI shielding materials. In order to effectively shield against electromagnetic interference (EMI), this study developed a variety of thermoplastic polyurethane (TPU)-based nanocomposites in conjunction with CoFe2O4 nanoparticles and graphite. The filler percentage and nanocomposite thickness were tuned and optimized. The designed GF15-TPU nanocomposite, which has a 5 mm thickness, 15 weight percent cobalt ferrite nanoparticles, and 35 weight percent graphite, showed the highest total EMI shielding effectiveness value of 41.5 dB in the 8.2-12.4 GHz frequency range, or 99.993% shielding efficiency, out of all the prepared polymer nanocomposites. According to experimental findings, the nanocomposite's dipole polarization, interfacial polarization, conduction loss, eddy current loss, natural resonance, exchange resonance, multiple scattering, and high attenuation significantly contribute to improving its electromagnetic interference shielding properties. The created TPU-based nanocomposites containing graphite and CoFe2O4 nanoparticles have the potential to be used in communication systems, defense, spacecraft, and aircraft as EMI shielding materials.Ministerstvo Scaron;kolstv, Mldezcaron;e a Tecaron;lovchovy [RP/CPS/2022/007]; Ministry of Education, Youth; Tomas Bata University in Zlin, Czech Republic [IGA/CPS/2023/006]; Internal Grant Agenc
Investigation of recycled polyol produced from semi-rigid polyurethane foam outsourced from the automotive industry
No full textPolyurethane, as a versatile polymer prepared by the polyaddition of isocyanates and hydroxyl group containing compounds, is widely used in the automotive industry and with an upcoming change of European legislation becomes recycling increasingly important as an alternative to landfilling or incineration. Glycolysis is one of the chemical degradation processes used to transform polyurethane waste using simple glycols as the degradation agents into a raw material. Single phase glycolysis was used to produce recycled polyol from polyurethane semi-rigid foam dedicated for headliner production. This paper is focused on comparison of obtained recycled polyol with the original fossil-based polyol with effect on hydroxyl number and viscosity. Infrared spectroscopy was carried out for identification of organic compounds. The result shows increased hydroxyl number and viscosity of recycled polyol versus original polyol. Reactivity of mixture containing recycled polyol was slower, but foam appearance was comparable to foam produced from original polyol. The research was supported by the BASF company
Total Quality Management 4.0 framework: Present and future
No full textUtilising socio-technical system theory, this study explores the Total Quality Management 4.0 (TQM 4.0) framework on the integration of quality management principles and industry 4.0 tools. The systematic literature review technique was applied to 203 articles from the Web of Science database to establish a theoretical framework for TQM 4.0. After an in-depth analysis of twenty key papers, twenty-one indicators for TQM 4.0 practices are proposed. Using the Pareto analysis, thirteen of the most important are identified. The research also explores the five major pillars of TQM 4.0, including technical elements, social elements, smart organisation, smart factory, and smart product. The study thoroughly understands TQM 4.0 and its related trending topics by employing a bibliometric technique to examine the publications’ keywords. The result of the bibliometric analysis shows that TQM 4.0 research addresses not only issues associated with Industry 4.0 techniques, such as big data, artificial intelligence, and machine learning but also digital transformation, sustainability, and quality culture. Especially organisational performance has been a relatively recent topic of interest to TQM 4.0 researchers. The study provides a TQM 4.0 framework for scholars to conduct additional research and for practitioners to implement the TQM 4.0 to gain long-term sustainability, as well as provides an overview of the current TQM 4.0 and suggests possible future research trends in the TQM field.Finance Authority of Maine, FAME; Univerzita Tomáše Bati ve ZlíněInternal Grant Agency of FaME, Tomas Bata University in Zlin [IGA/FaME/2022/006
Experimental study on the optimization of the autoclave curing cycle for the enhancement of the mechanical properties of prepreg carbon-epoxy laminates
Get PDFIn this study, the influence of the technological parameters of autoclave curing on the resulting mechanical properties of laminates was investigated. The main criterion for optimizing the curing was to extend the processing window with a lower prepreg viscosity. At the same time, the issue of setting the pressure level before the heat ramp to the final cure temperature was also addressed. An experimental method of measuring the indentation viscosity of the prepreg was used to determine the viscosity profile. Despite the experimental nature of the method, the reliability of this method for rapid approximate identification of the processing window of the prepreg was verified by the results of the study. Several laminates with the same ply orientation were produced using the selected cure cycles, from which test specimens were cut with a water jet and inspected by confocal microscopy. The mechanical properties of tension and flexure were measured within the individual curing cycles using tests according to ISO standards. The data reported demonstrate that the experimental method of optimizing the curing parameters has successfully increased the selected mechanical properties. The resulting mechanical properties of the laminates were enhanced by up to 20% compared to the non-optimized cure cycle. The influence of the type of cure cycle on the resulting thickness of the cured laminate was evaluated in this study.Tomas Bata University in Zlín, TBU; Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/FT/2023/004
Digital transformation of strategic management of SMEs in the Czech Republic
Get PDFStrategic management of SMEs is perceived as crucial backbone of their business, as it impacts their business models and internal processes all the way up to digital innovation measured by the level of digital maturity. How do the strategic management factors influence the digital maturity? Through quantitative analysis of 76 respondents representing SMEs in the Czech Republic, the research data was collected and statistically tested. Results imply that strategic management factors affect the level of digital maturity. This paper contributes to prior literature by practical implementation of modified digital maturity model and by addressing the correlation of strategic management factors and the level of digital maturity. Limitations springing from sample site and environment are addressed and discussion on the results is conducted. Author proposes a conclusion that strategic management factors can be perceived as a driver of digital transformation, emphasizing the need for future research and practical discussion.Tomas Bata University in Zlín, TBUTomas Bata University in Zlin; Faculty of management and econom
Can Finland serve as a model for other developed countries? Assessing the significance of energy efficiency, renewable energy, and country risk
No full textThe Sustainable Development Goal (SDG) that emphasizes sustainable and affordable energy presents a practical pathway to achieve sustainable growth. Moreover, this goal aligns with SDG 13, which focuses on climate action. Nonetheless, it is important to consider factors such as political and financial risk, as they can influence climate action efforts and the renewable energy sources adoption. Hence, this study broadens the conversation surrounding CO2 emission reduction and the achievement of Sustainable Development Goals (SDGs). It accomplishes this by investigating the interplay between renewable energy, political risk, financial risk, and CO2 emissions in Finland spanning from 1990/Q1 to 2021/Q4. Notably, this research distinguishes itself through its exploration of these complex connections, employing a wavelet-based quantile methodology. Unlike traditional quantile regression, which can only reveal connections between variables within each quantile, the wavelet-based quantile approach enables the simultaneous capture of correlations across quantiles and periods. The results show that in the long-term and across all quantiles (0.01–0.99), energy efficiency, specifically gas and oil efficiency, lessens CO2. In addition, low financial and political risks improve ecological quality by lessening CO2 across all periods and quantiles (0.01–0.99). The paper outcomes serve as a basis for formulating a policy framework aimed at achieving SDG 7 and SDG 13 in Finland
Influence of thermal degradation on the crystallization of poly(butylene terephthalate)
No full textOur work reveals a notable shift in the crystallization temperature (Tc) of poly(butylene terephthalate) (PBT) at which crystallization occurs due to exposure to prolonged thermal degradation at 270°C in an environment of nitrogen gas. The initial Tc of 193°C undergoes a marked decrease, settling at 133°C, which signifies a considerable 60°C shift towards lower temperature ranges. This transition is discernible across three distinct degradation stages: an initial phase of increase, an intermediate phase characterized by a sharp decline, and a subsequent late stage of the degradation phase characterized by a more moderate decrease in Tc. Both crystallinity and crystallization kinetics consistently mirror this pattern, demonstrating an initial rise, a rapid subsequent drop, and a gradual decline in the late-stage period. Evident from the presence of two melting peaks, the research implies differing lamellar thicknesses. As the degradation progresses, the melting points of these peaks, denoted as Tm1 and Tm2, decline at 38 and 41°C, respectively. Validation of the degradation-induced changes is provided by a small angle X-ray scattering (SAXS), which corroborates the observed decrease in the long period (L). A contextualization of the results against prior studies underscores analogous trends in the alteration of crystallization behaviour consequent to degradation.U niversity of Tomas Bata in Zlin, (IGA/FT/2023/008
Knowledge-based circular economics model for sustainable competitiveness: framework development and analysis
Get PDFGiven the numerous changes in global consumption and production models that have occurred in recent years, promoting the development of a circular economy and a knowledge economy would appear to be an appropriate shift for sustainable development and competitiveness, yet no previous studies have integrated their adoption for sustainable competitiveness from the business aspects. This study aims to integrate knowledge-based circular economics adoption for sustainable competitiveness. The research conducts a comprehensive literature review and a critical analysis of secondary data from a real-world case. The main results are a framework development of knowledge-based circular economics and a critical analysis of a modified model toward sustainable competitiveness, that addresses the above gap and derives the originality and novelty of the paper. Future research is proposed in which statistical software, such as SPSS and SmartPLS-SEM, would be applied to validate hypotheses.FaME TBU, (IGA/FaME/2022/005); National Technical Library in PragueNational Technical Library in Prague; Internal Grant Agency of FaME TBU in Zlin [IGA/FaME/2022/005