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Galloping of insulated bundled overhead line - nonlinear numerical analysis in time domain
Macháček, Michael; Hračov, Stanislav
2024 - anglický
Our contribution focuses on a 3D numerical nonlinear analysis of galloping in a specific bundled overhead line with ice accretion. We studied the susceptibility to this self-excited oscillation, critical onset wind speeds, and global dynamic response of a very low-tensioned line with simulated icing observed on similar real conductors. Due to the highly nonlinear mechanical behavior of such a flexible cable, we employed the Newmark integration method combined with the iterative Newton-Raphson method. We analyzed two numerical models of the overhead line loaded by the wind: one assuming nonlinearity only in the wind load, while retaining the linearity of the mechanical system itself, and the other representing a fully nonlinear system including geometrical nonlinearity. Our analysis revealed that the determined critical wind speeds for the onset of galloping are in relatively close ranges for both models. However, numerical simulations with the fully nonlinear system indicated significantly lower amplitudes of limit cycle oscillations, especially at higher wind speeds, compared to the linear model of the line. This underscores the necessity of using fully nonlinear models during the design stage of such low-tensioned aerial conductors.
Klíčová slova:
aerial bundled conductors; wind effects; galloping; limit cycle oscillation
Plné texty jsou dostupné v digitálním repozitáři Akademie Věd.
Galloping of insulated bundled overhead line - nonlinear numerical analysis in time domain
Our contribution focuses on a 3D numerical nonlinear analysis of galloping in a specific bundled overhead line with ice accretion. We studied the susceptibility to this self-excited oscillation, ...
The effect of using ai in education: an empirical study conducted in Greek private high schools
2024 -
Klíčová slova:
umělá inteligence; ChatGPT; GEMINI; vzdělávání; výuka; učení
Plné texty jsou dostupné v knihovně ZČU.
The effect of using ai in education: an empirical study conducted in Greek private high schools
Intelligent electrical installations in primary school education
2024 -
Klíčová slova:
žáci; první stupeň základní školy; druhý stupeň základní školy; programování; inteligentní elektroinstalace; moderní technologie
Plné texty jsou dostupné v knihovně ZČU.
Intelligent electrical installations in primary school education
Environmental gamebook as educational aid for lower primary school
2024 -
Klíčová slova:
RVP; environmentální výchova; průřezová témata; edukace; gamifikace; gamebook
Plné texty jsou dostupné v knihovně ZČU.
Environmental gamebook as educational aid for lower primary school
Electrochemical Properties of Pretomanid. New drug for Tuberculosis Treatment
Deri, M.; Vespi, M.; Giannarelli, S.; Hromadová, Magdaléna
2024 - anglický
The electrochemical behavior of Pretomanid (PA 824) has been investigated in acetonitrile by cyclic voltammetry at different scan rates and compared to dimetridazole reduction in order to elucidate its redox mechanism. Both compounds show similar reduction behavior in the aprotic solvent that involves one electron transfer to the nitro group. The reduction of Pretomanid is more difficult and the stability of its nitro anion radical is much lower compared to the dimetridazole molecule.
Klíčová slova:
pretomanid; dimetridazole; cyclic voltammetry; reduction mechanism
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Properties of Pretomanid. New drug for Tuberculosis Treatment
The electrochemical behavior of Pretomanid (PA 824) has been investigated in acetonitrile by cyclic voltammetry at different scan rates and compared to dimetridazole reduction in order to elucidate ...
Redox Properties of Pyrene-Cyclohexene Conjugates – Electrochemical Study
Koláčná, Lucie; Čubiňák, M.; Tobrman, T.; Ludvík, Jiří
2024 - anglický
The series of 16 compounds for "organic electronics" comprising the double-bond cyclohexene core extended by pyrene and/or other aromatics were electrochemically characterized by rotating disk voltammetry in N,N-dimethylformamide. Due to multiple substitutions, the resulting potential gap represents the sum of all substituent effects. Different combinations of substituents can be used to achieve the desired properties of cyclohexene-pyrene derivatives. The electrochemical data presented in this contribution facilitate further tuning of properties of these molecules and systems to achieve features required in material chemistry just by means of chemical modification.
Klíčová slova:
pyrene; cyclohexene; conjugation
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Redox Properties of Pyrene-Cyclohexene Conjugates – Electrochemical Study
The series of 16 compounds for "organic electronics" comprising the double-bond cyclohexene core extended by pyrene and/or other aromatics were electrochemically characterized by rotating disk ...
Electrochemical Valorization of Lignocellulosic Biomass Amination of Furfural and 5-Hydroxymethylfurfural
Donkeng Dazie, Joel; Koláčná, Lucie; Urban, Jiří; Lamač, Martin; Ludvík, Jiří
2024 - anglický
Furfural (FF) and 5-hydroxymethylfurfural (HMF) isolated from waste lignocellulosic biomass represent renewable sources. The present contribution deals with the transformation of FF and HMF into furfuryl amines which are important precursors namely for pharmaceutical synthesis. First, FF and HMF underwent condensation reactions with various amines which were electrochemically monitored to optimize the process. The resulting Schiff bases were identified by NMR and subsequently electrochemically reduced in basic media. The vicinal diamine (aminopinacol) was the main product besides the expected furfuryl amines. This reaction is a contribution to green synthesis because it was performed electrochemically, in water, and without any metallic catalysts.
Klíčová slova:
furfural; 5-hydroxymethylfurfural; (di)amines
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Valorization of Lignocellulosic Biomass Amination of Furfural and 5-Hydroxymethylfurfural
Furfural (FF) and 5-hydroxymethylfurfural (HMF) isolated from waste lignocellulosic biomass represent renewable sources. The present contribution deals with the transformation of FF and HMF into ...
Electrochemical Properties of Newly Synthesized Selaginpulvilins
Dostálová, L.; Sokolová, Romana; Schwarzová-Pecková, K.; Rýček, L.
2024 - anglický
The electrochemical properties of newly synthesized selaginpulvilin were investigated by cyclic voltammetry and UV-Vis spectroelectrochemistry. The subject of the study were two\nselaginpulvilins differing in the presence of a hydroxyl group in the media of 0.1 mol L-1 tetrabutylammonium hexafluorophosphate as supporting electrolyte in anhydrous acetonitrile. Both\ncompounds provided an oxidative signal in the positive region until +2.0 V.
Klíčová slova:
oxidation; cyclic voltammetry; selaginpulvilins
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
Electrochemical Properties of Newly Synthesized Selaginpulvilins
The electrochemical properties of newly synthesized selaginpulvilin were investigated by cyclic voltammetry and UV-Vis spectroelectrochemistry. The subject of the study were two\nselaginpulvilins ...
3D-printed Electrodes with Nearly Ideal Charge Transfer Characteristics
Vaněčková, Eva; Sebechlebská, Táňa; Kolivoška, Viliam
2024 - anglický
3D printing is an outstanding manufacturing tool for prototyping customized designs at reduced time and costs, having found applications in fields such as medicine or the automotive industry. The development of printable electrically conductive composite materials brought a revolution to electrochemistry, with 3D-printed electrodes being intensively studied from the viewpoint of\nanalytical performance and stability. However, it is often reported that 3D-printed electrodes have poor charge transfer characteristics, typically due to limited exposure of the electrically conductive phase at the composite surface to the surrounding solution. In this work, we devise and apply simple electrochemical activation procedures that lead to a significant improvement of charge transfer characteristics of 3D printed electrodes.
Klíčová slova:
three-dimensional printing; electrochemistry; electrodes
Plné texty jsou dostupné na vyžádání prostřednictvím repozitáře Akademie věd.
3D-printed Electrodes with Nearly Ideal Charge Transfer Characteristics
3D printing is an outstanding manufacturing tool for prototyping customized designs at reduced time and costs, having found applications in fields such as medicine or the automotive industry. The ...
Měření teploty při technické výchově
2024 -
V tomto pokusu budeme zkoumat šíření tepla při vrtání. Vyzkoušíme, jak se zahřívají ostré a tupé vrtáky při vrtání ocelové destičky
Klíčová slova:
vrtání; teplo; experiment
Plné texty jsou dostupné v knihovně ZČU.
Měření teploty při technické výchově
V tomto pokusu budeme zkoumat šíření tepla při vrtání. Vyzkoušíme, jak se zahřívají ostré a tupé vrtáky při vrtání ocelové destičky
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