Tomas Bata University in Zlín
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Development and analyses of a lever system for a newly designed self-equalising thrust bearing
Get PDFThrust bearings are undoubtedly one of the essential parts of turbines and compressors. However, there are many cases in which asymmetric load occurs on the bearings due to e.g. thermal deformations, production inaccuracies or a simple deflection of the shaft. The presented research deals with some basic steps involved in comprehensive research related to developing a new selfequalising thrust bearing. It focuses on the design of its most crucial part - lever, which is responsible for the proper equalising functionality. The study aimed to design a new type of lever geometry, create its numerical model, and, through numerical analysis and calculations, predict its useability in real conditions. According to von Mises hypothesis, stresses were evaluated, as well as contacts and stiffness according to Hertz's theory. The lever was modelled in two sizes, which suit the bearings representing the most often used types in powerful machines. For the levers' design and production, the steel 34CrNiMo6 has been used in a refined state with a yield strength of 900 MPa. The results achieved within the experimental static tests and verifications in operating conditions confirmed the correctness of the final geometry design of the levers, its sufficient stiffness, as well as good functionality of the thrust bearing and its reliability.Ministerstvo školstva, vedy, výskumu a športu Slovenskej republiky: APVV-19-0550; Kultúrna a Edukacná Grantová Agentúra MŠVVaŠ SR, KEGA: 005TUKE-4/2021Ministry of Education, Science, Research and Sport of the Slovak Republic [APVV-19-0550, KEGA 005TUKE-4/2021
COVID-19 pandemic and future business prospects: A conceptual study
Get PDFUnfortunately, the COVID-19 pandemic has disrupted the business environment worldwide mainly through the shift from physical to virtual (e-business) interaction. Yet, innovative ideas keep emerging out of this calamity. In this respect, this article aims to provide a rudimentary framework to understand business prospects that could arise through recognizing the changes in the business environment as a result of the pandemic. In doing so, we reviewed and conceptualized scanty works that are connected to the current research theme together with few interviews from business owners. We found that the COVID-19 pandemic has not only done harm to the business environment, but it led to a swift positive transformation (future business prospects) to both companies and customers. Major business prospects identified in the research study include - (1) Technology adoption and innovation, (2) Innovative marketing, and (3) Improved hygienic conditions in the business environment. The study, therefore, encourages business owners and practitioners to intensify the integration of technology to revamp their service delivery strategies. In other words, firms are recommended to engage in technological investment for their continuity and growth in the medium to long term.Tomas Bata University in Zlin [IGA/FaME/2021/005, IGA/FaME/2020/002
Sustainable competitiveness: How does global competitiveness index relate to economic performance accompanied by the sustainable development?
Get PDFThe research under discussion remains whether higher competitiveness of a country brings higher economic performance and sustainable growth, e.g., in the V4 region. The objective of the paper is to provide the results of extensive research based on verified Eurostat data to explore this research challenge in the V4 countries during the period of 2007-2019. Simultaneously, the objective is to link the country's economic performance (GDP) to urgent challenges of the contemporary world in the form of sustainability and life quality. In the paper, linear regression, multiple linear regression, and ANOVA were used. A significant impact of the Global Competitiveness Index (GCI) on the level of GDP, and the subsequent positive effect of GDP level on sustainability and life quality indicators has been demonstrated. Our research findings propose an unconventional sustainable competitiveness mechanism. The conclusion outlines the direction from improved competitiveness through higher economic performance reinforcing R&D expenditure and hightech employment to better sustainability and well-being. Moreover, the research results bring initial empirical evidence of the functionality of the proposed mechanism in the V4 countries. Based on this, we can offer policymakers the key research findings pointing at the sustained economic growth accompanied by higher ecology, including life quality. At the same time, the drivers of this development are presented in more detail in our paper
Constitutive models that exceed the fitting capabilities of the Herschel–Bulkley model: A case study for shear magnetorheology
Get PDFA significant proportion of non-Newtonian fluids exhibits the phenomena of shear-thinning and yield stress. The Herschel-Bulkley model is probably the most widespread equation to describe the rheological behaviour of such systems, although greater attention is being paid to discerning more accurate mathematical models for visco-plastic systems. In this regard, the work presented herein investigates existing, unconventional viscoplastic models and evaluates their fitting and predictive capabilities in relation to collected magnetorheological data. The four-parameter models of modified Carreau, modified Cross (and its variant extended with the Quemada equation), Shulman and Nasiri-Ashrafizadeh were applied to appraise the shear data of the magnetorheological fluids. Their suitability was also statistically evaluated and compared with that attained for the conventional Herschel-Bulkley model and recently employed analogues, such as the Robertson-Stiff and Mizrahi-Berk models. It was found that the performance of all models for describing magnetorheological flow curves was adequate, with relatively high correlation coefficients. Applying the four-parameter models, however, provided higher accuracy, demonstrated by notably reduced statistical coefficients of regression analysis. Both of the modified Carreau and Cross models exhibited superior fitting performance (up to 4-times lower root mean square error), while the Shulman and Nasiri-Ashrafizadeh models proved questionable in application. Although interpreting four-parameter equations is a rather complex matter, they provided more reliable prediction of shear stress data across the entire range of shear rate than the Herschel-Bulkley approximation, especially the modified Carreau and modified Cross models. It is believed that these findings can be extended to describe the rheology of other systems with viscoplastic characteristics.Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Akademie Věd České Republiky, AV ČRproject DKRVO - Ministry of Education, Youth and Sports of the Czech Republic [RP/CPS/2022/007
A concept of nowcasting of convective precipitation using an X-band radar for the territory of the Zlín Region (Czech Republic)
No full textThe paper presents the first results of precipitation nowcasting that is targeted to a smaller administrative unit in the Czech Republic (Zlin region), to aid better preparedness of the staff of crisis management of the region. The methodology is based on the scans of the X-band radar located at Holegov (240 m above the sea level). More specifically, the CAPPI 2000 data were used, which, in the first step, were converted into a 4-category system of warning classes (0: no event; 1/2/3: weak/moderate/strong events) for all the 13 smaller administrative districts of the region. Besides the radar echo extrapolation method TITAN that is operationally available in the region, a further extrapolation-based nowcasting method (COTREC) was selected and compared with a third approach (Persistence) that supposes no changes in the observed field of precipitation. The predictions of the CAPPI warning classes within the 13 districts with the lead times ranging from 5 to 30 min with 5 min intervals were compared with the observed CAPPI warning classes. Since the analysis was carried out in the framework of imbalanced ordinary regression, several issue-specific binary metrics had to be developed. Our first results indicate that the COTREC model outperformed the TITAN method, both in terms of the POD (probability of detection) and FAR (false alarm ratio) statistics, for all the lead times and the relevant binary metrics. Further we found that the reliability of the predictions sharply decreases with increasing lead times, and they are of low practical usability beyond the horizon of 30-40 min.VI20192022134; Ministerstvo Vnitra České RepublikyMinistry of Interior of the Czech Republic within the program `Security Research Programme of the Czech Republic [VI20192022134
Using pagebuilder to teach web development
No full textWeb design is one of the branches of IT that is evolving very fast, like most IT fields. At the same time, it is also one of the first things students encounter when learning programming There are two ways of creating web pages - classic using HTML, PHP, etc., and visual using editors and pagebuilders. This article aims to introduce the reader to web development and its teaching. The report summarizes the main advantages and disadvantages of traditional web development and manual programming and compares them with today's modern methods through pagebuilders in web CMS. The article concludes by answering SEO questions and the advantages and disadvantages of using pagebuilder solutions
AVR technologies in sustainable tourism: A bibliometric review
No full textAn extensive, PRISMA-led bibliometric analysis of scientific literature from the last 20 years was conducted to extract future research agenda in the niche field of sustainable tourism and the application of virtual reality+ technologies (extended, mixed, hyper, and augmented). The field being investigated contains significant opportunities through meta-analysis methods like linear-logarithmic transformations, coupling clustering, and network analysis. Astringent keyword inclusion rule ensured that the most pertinent scientific literature entered the analysis. The authors used critical content analysis parameters like Cohen's kappa to include the best fit papers. This bibliometric analysis convenes the need to focus on emerging areas like cyber-neurotics, telekinesis, cyber-optics, and gamification to provide impetus to sustainable consumption and production in the tourism and travel industry. The paper expresses the paradigm shift in research topics as the world enters the COVID-19-induced pandemic and its impact on future research endeavours.OP RDE project Junior grants of Tomas Bata University in Zlin [CZ.02.2.69/0.0/19_073/0016941
Literature review on circular economics adoption for the Vietnam economy
No full textThe circular economy has been widely used in all industries and services in developed countries for sustainability. This is, however, a new concept in emerging economies. In Vietnam, although the government also has the overall strategic orientation for circular economy deployment, as well as a few large enterprises have implemented its principles in several operations and businesses, there are still many shortcomings compared to developed countries. Therefore, this paper aims to fill the gap to contribute to the thorough review of the literature that underpins circular economy practices in the fields of manufacturing, logistics, and supply chain. The main results of this research are (a) a literature review on circular economy examined in two aspects of government policies and high-tech applications in the light of sustainability; (b) a conceptual framework of the circular economy business model for the adoption and its hypothesis; (c) future research agendas to develop statistical analysis to evaluate and validate the proposed framework, as well as developing an optimization model for a case study in Vietnam.Internal Grant Agency of FaME TBU in Zlin [IGA/FaME/2020/011]; Southeast Asia regio
Effect of wear on the vibrating behaviour of the tool at turning CW724R alloy
No full textThe development of new materials and technologies also significantly affects traditional methods of component production, as it forces companies to increase the efficiency of the production process and thus remain competitive. This pressure also brings new challenges in the field of machining. The article deals with the influence of wear on the vibration behaviour of the tool when turning CW724R alloy. The aim of the research is to know the frequency response of the system to different sizes of tool wear, which causes deterioration of the quality of machined parts and instability of the entire cutting process. A specific method of artificial wear of cutting tool was applied to determine the vibration behaviour of a worn tool. To reduce the number of experimental measurements, the methodology of the orthogonal non-rotating composition plan was chosen. The matrix of two independent variables (cutting speed versus artificial wear) was selected to evaluate the relationships between them under conditions of the constant depth of cut and feed, which was processed by the multiple linear regression methodology. Finally, a dependence of vibrations on cutting speed and wear rate for evaluated material was plotted in a spatial graph. © 2022 IEEE
Electrothermal actuation and release of adhesiveness of conductive carbon nanotube/epoxy composites by Joule heating
Get PDFThe effect of an embedded electro-conductive multi-walled carbon nanotube (MWCNT) nanopaper in an epoxy matrix on the release of the frozen actuation force and the actuation torque in the carbon nanotube nanopaper/epoxy composite after heating above its glass transition temperature is assessed. The presence of the nanopaper augments the recovery of the actuation stress by the factor of two in comparison with the pure epoxy strip. The strengthening of the composite is attributed to the interlocking of the carbon nanotubes with the epoxy. Moreover, the internally heated electro-conductive carbon nanotube nanopaper/epoxy composite not only substantially shortens curing time while retaining comparable strength of the adhesive bonding of the steel surfaces but also enables a release of such bonds by repeated application of DC current.Tomas Bata University in Zlin, TBU: 67985874, CZ.02.2.69/0.0/0.0/16_028/0006243; Akademie Věd České Republiky, AV ČROP VVV project The Development of Capacity for Research and Development of TBU in Zlin [CZ.02.2.69/0.0/0.0/16_028/0006243]; Czech Academy of Sciences, Czech Republic [67985874