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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, ...
Growth and Phosphorus Dynamics During Tolypothrix tenuis Cultivation – a Cyanobacterium of Biotechnological Potential
Mušálková, Petra
2024 - English
Here I investigated the course of biomass growth, phosphorus uptake and changes in intracellular phosphorus content in T. tenuis in a batch cultivation. Cultivation experiment was held in multiple bubble columns during a light regime (alternating light and dark periods 16 and 8h). Thanks to this experiment I was able to obtain a growth curve of T. tenuis. The decrease of phosphorus concentration in the medium was disproportionally faster\nthan biomass growth resulting in significant oscillations of phosphorus content in the biomass, which are typical characteristics for LPU. It was also observed, that after all phosphorus was removed from the medium, the algae growth continues over time, while obviously utilizing intracellular phosphorus reserves. These findings are valuable in course of using this cyanobacterium for efficient bioremediation of eutrophic water based on phosphorus removal by targeted algae cultivation.
Available in a digital repository NRGL
Growth and Phosphorus Dynamics During Tolypothrix tenuis Cultivation – a Cyanobacterium of Biotechnological Potential
Here I investigated the course of biomass growth, phosphorus uptake and changes in intracellular phosphorus content in T. tenuis in a batch cultivation. Cultivation experiment was held in multiple ...
Influence of Material Properties and Mixing Dynamics on Heat Transport in Granular Materials
Kokavcová, Anna
2024 - English
This study evaluates the effect of rotational speed on heat transfer and analyzes particle motion at different stirrer rotational frequencies to understand how primary and secondary flows affect heat transfer efficiency. It also examines the effect of Young’s modulus on heat transfer at different agitator\noperating speeds. Key simulation parameters and their influence 33 on heat transfer efficiency are detailed to improve the reproducibility and applicability of the results.
Keywords:
granular mixing; heat transfer; DEM
Available in digital repository of the ASCR
Influence of Material Properties and Mixing Dynamics on Heat Transport in Granular Materials
This study evaluates the effect of rotational speed on heat transfer and analyzes particle motion at different stirrer rotational frequencies to understand how primary and secondary flows affect heat ...
Entrepreneurship during pandemics and crises in the context of gender inequalities. Policy brief.
Švarcová, Markéta; Pospíšilová, Marie
2024 - Czech
Whether the pandemic can be perceived as an opportunity to reduce gender inequality in entrepreneurship was the main question of the participatory workshop that we organized at the Institute of Sociology on March 13, 2024. The discussion during the participatory workshop focused on the barriers that women entrepreneurs face, the tools they can use to overcome them, the introduction of a attendance allowance for entrepreneurs, and the availability and usability of gender-disaggregated data. This policy brief write down the views of relevant stakeholders in the business sector on the topic of eliminating gender inequalities in the entrepreneurship that were expressed during the workshop. Zda lze vnímat pandemii jako příležitost pro snížení genderové nerovnosti v podnikání bylo hlavní otázkou participativního workshopu, který jsme uspořádaly v Sociologickém ústavu 13. 3. 2024. Diskuze v rámci participativního workshopu byla zaměřena na bariéry, kterým čelí ženy podnikatelky, na nástroje, které mohou využívat pro jejich překonání, na zavedení ošetřovného pro podnikající a dostupnost a využitelnost dat členěných dle pohlaví. Tento policy brief zaznamenává názory relevantních stakeholderů v oblasti podnikání na téma odstraňování genderových nerovností v podnikatelském prostředí, které v rámci workshopu zazněly.
Keywords:
Entrepreneuship; gender; data; attendance allowance; barriers
Available in digital repository of the ASCR
Entrepreneurship during pandemics and crises in the context of gender inequalities. Policy brief.
Whether the pandemic can be perceived as an opportunity to reduce gender inequality in entrepreneurship was the main question of the participatory workshop that we organized at the Institute of ...
Řízení pracovníků prostřednictvím umělé inteligence
VÚBP
2024 - Czech
Vyšší úroveň automatizace a konstantní sledování pracovníků digitálními technologiemi v mnoha případech omezí mezilidský kontakt a zvýší tlak na pracovní výkonnost, což může mít škodlivé účinky na duševní zdraví pracovníků.
Keywords:
digitalizace; BOZP; bezpečnost práce; monitorovací systémy; umělá inteligence; AI; OSH; occupational safety; artificial intelligence; monitoring systems
Available in a digital repository NRGL
Řízení pracovníků prostřednictvím umělé inteligence
Vyšší úroveň automatizace a konstantní sledování pracovníků digitálními technologiemi v mnoha případech omezí mezilidský kontakt a zvýší tlak na pracovní výkonnost, což může mít škodlivé účinky na ...
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. ...
Cultivation of Limnospira Maxima and Utilization of its Fresh Biomass in Human Nutrition
Vásquez, Claudia
2024 - English
This project aims to fill this gap by presenting new insights into its consumption as an alternative to dried spirulina and offering recommendations\nfor safe storage.
Keywords:
Limnospira maxima; dietary supplements; bioengineering
Available in a digital repository NRGL
Cultivation of Limnospira Maxima and Utilization of its Fresh Biomass in Human Nutrition
This project aims to fill this gap by presenting new insights into its consumption as an alternative to dried spirulina and offering recommendations\nfor safe storage.
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