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Number of found documents:
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Electrochemical Properties of Newly Synthesized Selaginpulvilins
Dostálová, L.; Sokolová, Romana; Schwarzová-Pecková, K.; Rýček, L.
2024 - English
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.
Keywords:
oxidation; cyclic voltammetry; selaginpulvilins
Available on request at various institutes of the ASCR
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 - English
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.
Keywords:
three-dimensional printing; electrochemistry; electrodes
Available on request at various institutes of the ASCR
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 ...
Book of Abstracts. 19th Youth symposium on experimental solid mechanics
Kytýř, Daniel; Zlámal, Petr; Pagliaro, A.; Doktor, T.
2024 - English
The YSESM symposium provides a forum for young researchers and engineers, PhD students and students dealing with subjects of experimental mechanics. The Symposium concentrates on current work in all areas of experimental research and its application in solid and fluid mechanics. The topic will particularly concern to: Conventional and advanced experimental methods in solid and fluid mechanics - Non-destructive testing and inspection - Measurements in material science - Computer assisted testing and simulation - Engineering design simulation - Hybrid methods, experimental techniques – Numerical simulation - Optical methods and image processing - Measurements in biomechanics - Sensor techniques for micro- and nano-applications - Measurement methods for forensic engineering
Keywords:
experimental mechanics; solid mechanics; fluid mechanics
Available at various institutes of the ASCR
Book of Abstracts. 19th Youth symposium on experimental solid mechanics
The YSESM symposium provides a forum for young researchers and engineers, PhD students and students dealing with subjects of experimental mechanics. The Symposium concentrates on current work in all ...
Galloping of insulated bundled overhead line - nonlinear numerical analysis in time domain
Macháček, Michael; Hračov, Stanislav
2024 - English
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.
Keywords:
aerial bundled conductors; wind effects; galloping; limit cycle oscillation
Available in digital repository of the ASCR
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, ...
COVID-19 and political preferences through stages of the pandemic: the case of the Czech Republic
Bičáková, Alena; Jurajda, Štěpán
2024 - English
We track the effects of the COVID-19 pandemic on political preferences through ‘high’ and ‘low’ phases of the pandemic. We ask about the effects of the health and the economic costs of the pandemic measured at both personal and municipality levels. Consistent with the literature, we estimate effects suggestive of political accountability of leaders during ‘high’ pandemic phases. However, we also find that the pandemic political accountability effects are mostly short-lived, and do not extend to the first post-pandemic elections.
Keywords:
COVID-19; political preferences; election outcomes
Fulltext is available at external website.
COVID-19 and political preferences through stages of the pandemic: the case of the Czech Republic
We track the effects of the COVID-19 pandemic on political preferences through ‘high’ and ‘low’ phases of the pandemic. We ask about the effects of the health and the economic costs of the pandemic ...
Flow simulations approach for flocculation tanks
Idžakovičová, Kristýna; Bílek, Vojtěch; Haidl, Jan; Isoz, M.; Pivokonský, Martin
2024 - English
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and savings of operational costs. However, it is currently based on trial-and-error experimental approaches. In this contribution, we focus on flow modeling in stirred flocculation tanks that would, after coupling with a calibrated model of particle aggregation, enable simulationbased flocculation optimization. Despite the abundance of literature on stirred tank modeling, there is no universal agreement on the methodology used to describe turbulence nor on the approach to the computational mesh creation. Consequently, there is no unified methodology for simulations and their validation. To address this, we present a best-practice methodology for economical, yet reliable flow simulations in the said device. This methodology includes the choice of the turbulence model, the approach to the design of a high quality mesh suitable for arbitrary geometries, and results evaluation. It is developed based on an extensive literature review, a multitude of flow simulations using several meshes of progressively higher quality and resolution, and various strategies to converge to steady-state flow conditions. The simulation quality indicators used here involve comparison with the experimental data on fluid velocity, stirrer power output, and flow rate through the impeller zone. Additionally, the resulting flow simulation models are compared using tracer transport simulations, hinting at their potential for coupling with particle aggregation models.
Keywords:
flocculation tank; stirring; MRF; CFD; OpenFOAM
Available in digital repository of the ASCR
Flow simulations approach for flocculation tanks
Flocculation in water treatment facilities plays a key role in the separation of colloidal inorganic and organic substances. Its optimization leads to a significant increase in its efficiency and ...
Numerical study of the steady airflow in the human respiratory system during inhaling and exhaling
Lancmanová, Anna; Bodnár, Tomáš
2024 - English
This paper presents some of the initial results of the numerical simulations of a steady turbulent flow in human upper airways during inhalation and exhalation. The mathematical model is based on the system of Reynolds-Averaged incompressible Navier-Stokes equations complemented by the SST k − ω turbulence model. The simulations were performed using finite-volume open source solver OpenFOAM on a realistic three-dimensional geometry. The main aim of this particular study is to verify the computational setup with special focus on appropriate choice and implementation of boundary conditions. The prescribed boundary conditions are chosen to mimic the physiological conditions during normal breathing cycle. This study aims to gain an insight into the airflow behavior during the inhalation and exhalation process by comparing the results of two distinct simulations corresponding to two different (opposite) flow rates . The obtained local flow rates and flow fields for both cases are presented and mutually compared. This initial work should serve as a foundation for future more complex simulations that will include the time-dependent and compressible effects.
Keywords:
human airways; incompressible Navier-Stokes; OpenFOAM
Available in digital repository of the ASCR
Numerical study of the steady airflow in the human respiratory system during inhaling and exhaling
This paper presents some of the initial results of the numerical simulations of a steady turbulent flow in human upper airways during inhalation and exhalation. The mathematical model is based on the ...
Assessment of the Presence of Hazardous Components in Textile Waste
Shtukaturova, Anastasia
2024 - English
An up-flow percolation test was chosen to identify and characterize heavy metals and PFAS constituents in textile waste. Up-flow column percolation tests are used on a laboratory scale to assess the leaching behavior of a hazardous substance from a waste in a given state as a function of time. The test was performed according to the European Technical Standard CEN/TS 14405. Preliminary results showed the following heavy metals in the leachates Al, As, Co, Cr, Cu, Fe, Mn, Pb, Zn and Sb, with Al, Cr, Fe, Mn and Zn being predominant.
Keywords:
textile waste; percolation test; PFAS; heavy metals
Available in a digital repository NRGL
Assessment of the Presence of Hazardous Components in Textile Waste
An up-flow percolation test was chosen to identify and characterize heavy metals and PFAS constituents in textile waste. Up-flow column percolation tests are used on a laboratory scale to assess the ...
Drone Based Vertical Profiling of Black Carbon Aerosols at a Rural Background and an Urban Site in Central Europe
Julaha, Kajal
2024 - English
This research aims to assess the vertical distribution of BC aerosols using a drone and micro Aethalometer AE51 at two distinct sites in the Czech Republic: 1. NAOK (National Atmospheric Observatory Košetice) representing a regional background, and 2. MFF (Faculty of Mathematics and Physics in Prague) representing an urban site. At NAOK, a 250-meter measurement tower is accessible, providing a means to validate and calibrate the drone measurements.
Available in a digital repository NRGL
Drone Based Vertical Profiling of Black Carbon Aerosols at a Rural Background and an Urban Site in Central Europe
This research aims to assess the vertical distribution of BC aerosols using a drone and micro Aethalometer AE51 at two distinct sites in the Czech Republic: 1. NAOK (National Atmospheric Observatory ...
Vertical Gradients of Atmospheric Aerosols Chemical Composition
Kovářík, Jiří
2024 - English
Concentration of chemical species chosen as markers for AA source apportionment are evaluated with regard to atmospheric conditions, seasonal and daily cycles and compared between the two heights. This work adds to the current state of general knowledge about AACC.
Keywords:
vertical gradients; chemical composition; atmospheric aerosols
Available in a digital repository NRGL
Vertical Gradients of Atmospheric Aerosols Chemical Composition
Concentration of chemical species chosen as markers for AA source apportionment are evaluated with regard to atmospheric conditions, seasonal and daily cycles and compared between the two heights. ...
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