Tomas Bata University in Zlín
Institutional repository of Tomas Bata University LibraryNot a member yet
10673 research outputs found
Sort by
Evolutionary optimized 3D WiFi antennas manufactured via laser powder bed fusion
Get PDFThe swift and automated design of antennas remains a challenging aspect in research due to the specific design needs for individual applications. Alterations in resonance frequency or boundary conditions necessitate time-consuming re-designs. Though the application of evolutionary optimization and generative methods in general to antenna design has seen success, it has been mostly restricted to two-dimensional structures. In this work, we present an approach for designing three-dimensional antennas using a genetic algorithm coupled with a region-growing algorithm - to ensure manufacturability - implemented in Matlab manufactured via laser powder bed fusion (LPBF). As a simulation tool for optimization CST is used. The antenna has been optimized in a completely automated manner and was produced using the metal 3D printing technology LPBF and aluminium based AlSi10Mg powder. The presented concept, which builds upon previous two-dimensional techniques, allows for significant flexibility in design, adapting to changing boundary conditions, and avoiding the geometric restrictions seen in prior methods. The optimized antenna has a size of 3.01 cm × 3.43 cm × 1.67 cm and was measured in an anechoic chamber. According to measurements a minimum reflection coefficient of -19.95 dB at 2.462 GHz and a bandwidth of 308.8 MHz are observed. CST simulation results predict an efficiency of 98.91% and the maximum antenna gain is measured at 2.45 GHz to be 3.27 dB i. Simulations made with CST and Ansys HFSS and measurements are in excellent agreement with a deviation of the resonance frequency of only 0.13% , thus further establishing genetic algorithms as a highly viable option for the design of novel antenna structures.Austrian Agency for Education and Internationalisation (OeAD) [CZ 03/2022]; European Regional Development Fund (ERDF); Austria Wirtschaftsservice Gesellschaft (AWS) [P2372773]; University of Innsbruc
Evaluation of the viscoelastic properties of pork liver pâté during sterilisation observed in situ
Get PDFThe first aim of the study was to observe in situ changes in the viscoelastic properties of pork liver pâté during an increase in temperature (the target temperature of 122 °C), holding it (10 min), and the subsequent cooling thereof using a dynamic oscillatory rheometry equipped with a pressure cell. At the same time, the samples were treated according to the same sterilisation mode in an autoclave. The second objective was to characterise the physical, chemical and microscopic properties of the sterilised pork liver pâté samples after 7 days of storage at 5 °C. A sharp decrease in the values of the storage (G'; Pa) and loss (G''; Pa) moduli up to ≈58 °C was followed by a stagnation of these parameters up to ≈70 °C and a further increase in G' and G'' up to ≈85 °C. After cooling the sterilised samples, the G' and G'' values were significantly higher than those of the original untreated sample. Knowledge about the course of the viscoelastic moduli development during sterilisation and subsequent cooling and the quality characteristics of final food products is crucial for the control of these processes during manufacturing and for information important for pipeline transport. In the future, selected hydrocolloids could be evaluated as possible substances for confirmation of their effect on the viscoelastic properties during sterilisation.Army of the Czech Republic; Ministerstvo Obrany České Republiky, MOČRMinistry of Defence of the Czech Republi
The effect of cropping systems on environmental impact associated with winter wheat production - An LCA "Cradle to Farm Gate" approach
Get PDFThe demand for wheat production is increasing and is associated with environmental effects. To sustain the increased demand, there is a need to find sustainable methods of wheat production. The choice of cropping system can significantly affect the environmental burden of agricultural production systems. This study presents the results of monitoring emission loads resulting from winter wheat cultivation under different cropping systems: organic unfertilized (ORG), organic fertilized (ORG-F), conventional unfertilized (CON), and conventional fertilized (CON-F). The system boundaries include all the processes from “cradle to farm gate” and the functional unit was 1 kg of wheat grain. The primary data were obtained from experimental field trials and secondary data from Ecoinvent v3.5, WFLDB, and Agri-footprint v5.0 databases. The results of this study are related to eight impact categories. The SimaPro 9.2.0.1 software and ReCiPe Midpoint (H) V1.13/Europe Recipe H were used for calculation. The results show that fertilized variants recorded higher environmental impacts compared to the unfertilized variants. The results indicate that ORG-F was more environmentally friendly compared to the CON-F variant at the expense of lower yields. Overall, ORG imposes the lowest environmental impact and is deemed to be more environmentally friendly.Operational Program Integrated Infrastructure Project SMARTFARM 15
Comprehensive lipid hydrolysis observation in anaerobic digestion
No full textLipid hydrolysis monitoring, including especially glycerides, is necessary for comprehending the anaerobic digestion process in lipid-rich substrates processing. This reaction has not been investigated in such detail so far, despite its potential to be crucial in assuring a stable process. This study suggested and thoroughly validated an uncomplicated method of monitoring lipid hydrolysis during anaerobic digestion, achieving recovery values >95 % with an average relative standard deviation <5 %. Subsequently, the method was applied on the very first detailed observation of glyceride hydrolysis in the anaerobic sludge, tracking even changes in fatty acid profiles during anaerobic digestion. Results showed that lipid hydrolysis can take several days, thus likely affecting the whole anaerobic digestion of lipids. The method aims to provide answers to improve understanding of lipids' fate and their inhibition phenomena in anaerobic digestion.Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/CebiaTech/2022/002, RVO/CEBIA/2021/003)Tomas Bata University in Zlin [RVO/CEBIA/2021/003, IGA/CebiaTech/2022/002
Removal of endocrine disrupting chemicals from water through urethane functionalization of microfiltration membranes via electron beam irradiation
Get PDFPolyethersulphone (PES) membranes modified with urethane functional groups were prepared through an interfacial reaction using electron beam irradiation. The removal of eight endocrine disrupting chemicals (EDCs) was studied using both pristine and functionalized PES membranes. The prepared membranes underwent characterization using several techniques, including attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy, contact angle analysis, and measurements of pure water flux. Furthermore, dynamic adsorption experiments were conducted to evaluate the adsorption mechanism of the prepared membrane toward the eight EDCs. The urethane functionalized membranes were hydrophilic (52° contact angle) and maintained a high permeate flux (26000 L/h m2 bar) throughout the filtration process. Dynamic adsorption results demonstrated that the introduction of urethane functional groups on the membranes significantly enhanced the removal efficiency of 17β-estradiol, estriol, bisphenol A, estrone, ethinylestradiol, and equilin. The adsorption loading of 17β-estradiol on the functionalized PES membrane was 6.7 ± 0.7 mg/m2, exhibiting a 5-fold increase compared to the unmodified PES membrane. The membranes were successfully regenerated and reused for three adsorption cycles without experiencing any loss of adsorption capacity.Projekt DEA
A study on the positive impact of eWOM in eco-tourism destinations of Vietnam
Get PDFThis research study focuses on the positive impact of eWOM in determining the selection of eco-tourism destinations. A positive review of tourism destinations has significant images, content and experience. Its natural beauty, environment-friendly practices, sustainability, and other factors determine an eco-tourism destination. The paper's findings suggest that tourists research before selecting a destination. An honest review of a previous consumer has more impact on a potential customer. Travellers opt for online and offline media to judge the authenticity of the destination. This research paper also examines how electronic word of mouth (e-WOM) impacts the tourists' decision to select and visit eco-friendly destinations
Characterization of poultry gelatins prepared by a biotechnological method for targeted changes at the molecular level
Get PDFChicken collagen is a promising raw material source for the production gelatins and hydrolysates. These can be prepared biotechnologically using proteolytic enzymes. By choosing the appropriate process conditions, such changes can be achieved at the molecular level of collagen, making it possible to prepare gelatins with targeted properties for advanced cosmetic, pharmaceutical, medical, or food applications. The present research aims to investigate model samples of chicken gelatins, focusing on: (i) antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-3-etylbenzotiazolin-6-sulfonic acid (ABTS); (ii) the distribution of molecular weights via gel permeation chromatography with refractometric detection (GPC-RID); (iii) functional groups and the configuration of polypeptide chains related to molecular-level properties using Fourier transform infrared spectroscopy (FTIR); (iv) the microbiological populations on sabouraud dextrose agar (SDA), plate count agar (PCA), tryptic soy agar (TSA), and violet red bile lactose (VRBL) using the matrix-assisted laser desorption ionization (MALDI) method. Antioxidant activity towards ABTS radicals was more than 80%; activity towards DPPH radicals was more than 69%. The molecular weights of all gelatin samples showed typical α-, β-, and γ-chains. FTIR analysis confirmed that chicken gelatins all contain typical vibrational regions for collagen cleavage products, Amides A and B, and Amides I, II, and III, at characteristic wavenumbers. A microbiological analysis of the prepared samples showed no undesirable bacteria that would limit advanced applications of the prepared products. Chicken gelatins represent a promising alternative to products made from standard collagen tissues of terrestrial animals.Faculty of Technology; Tomas Bata University in Zlín, TBU, (IGA/FT/2023/008); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (RP/CPS/2022/002)Internal Grant Agency of the Faculty of Technology, Tomas Bata University in Zlin [IGA/FT/2023/008]; Ministry of Education, Youth, and Sports of the Czech Republic-program DKRVO [RP/CPS/2022/002
ESG performance and investment efficiency: The impact of information asymmetry
No full textThis paper investigates the relationship between firms' engagement in environmental, social, and governance (ESG) activities and corporate investment efficiency, using 1,094 firms from 21 countries in Europe, covering the years 2002–2019. We conduct our estimations using fixed effects panel data techniques and address potential endogeneity with instrumental variables (IV) estimations. We provide evidence that overall ESG engagement is positively and significantly associated with investment efficiency. Analyzing overinvestment and underinvestment scenarios shows that ESG engagement decreases only overinvestment problems. Within the underinvestment scenario, we observe that ESG engagement is beneficial only for firms with higher information asymmetries. Thus, information asymmetry matters in the underinvestment case. We next show that four firm-level channels—information asymmetry, financial constraints, cash flows, and risk—link ESG performance to investment inefficiency. Additional analysis shows that firms with extreme ESG scores (i.e., very low and very high) do not experience significant reductions in investment inefficiency. Altogether, our findings draw attention to the critical role of ESG performance and information asymmetry in determining corporate investment efficiency
Assessing and prioritizing biogas energy barriers: A sustainable roadmap for energy security
No full textPakistan is trying to alleviate energy poverty by tapping into the full potential of biogas. However, the production of biogas is hampered by a variety of barriers. Although many researchers have pointed out these barriers, their impact on Pakistan's biogas market remains unclear. This study prioritizes possible barriers and identifies the most practical solutions for energy security in the nation in an effort to bridge this knowledge gap. We find 25 sub-barriers and classify them into five major categories using a literature study and a modified Delphi approach. The analytical hierarchy process (AHP) is used to assign a priority ranking based on weight allocation to barriers. The most influential alternatives to these barriers have been prioritized using the Grey Technique for Order Preference by Similarity to Ideal Solution (G-TOPSIS). According to study findings, among the major categories, “monetary barrier” is the most significant barrier. The top sub-barrier is “high initial price.” “Suitable monetary rewards” and “improved specialized technology” have been proposed as the most viable alternative. Finally, study findings suggest essential and useful policy recommendations to speed up the current progress of biogas energy through coherent and consistent efforts
Giant response and selectivity of Hansen solubility parameters-based graphene-SBS co-polymer matrix composite room temperature sensor to organic vapours
Get PDFA styrene-butadiene-styrene co-polymer matrix nanocomposite filled with graphene nanoplatelets was studied to prepare chemiresistive volatile organic compounds (VOCs) room temperature sensors with considerable response and selectivity. Nanofiller concentration was estimated from the electrical conductivity percolation behaviour of the nanocomposite. Fabricated sensors provided selective relative responses to representative VOCs differing by orders of magnitude. Maximum observed average relative responses upon exposure to saturated vapours of the tested VOCs were ca. 23% for ethanol, 1600% for acetone, and the giant values were 9 × 106% for n-heptane and 10 × 106% for toluene. The insensitivity of the sensor to the direct saturated water vapour exposure was verified. Although high humidity decreases the sensor’s response, it paradoxically enhances the resolution between hydrocarbons and polar organics. The non-trivial sensing mechanism is explained using the Hansen solubility parameters (HSP), enabling a rational design of new sensors; thus, the HSP-based class of sensors is outlined.DKRVO, (RP/CPS/2022/007); Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT; Univerzita Tomáše Bati ve Zlíně, UTB, (IGA/CPS/2022/002, IGA/CPS/2023/006)Ministry of Education, Youth, and Sports of the Czech Republic-DKRVO [RP/CPS/2022/007]; Tomas Bata University in Zlin [IGA/CPS/2022/002, IGA/CPS/2023/006