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Mobile Robot in the Elevator: What Floor Am i On?
Krejsa, Jiří; Věchet, Stanislav; Chen, K.S.; Havelka, M.; Černil, M.
2022 - anglický
Wheeled mobile robots in multiple stories buildings have to use elevator to access arbitrary floor of the building. To do so, the control system must be able to detect and access elevator controls and also determine on which floor the elevator stopped. The paper deals with the latter problem, using the fusion of relative floor change detected by onboard accelerometer and absolute floor number detected by the processing of elevator information screen panel image acquired by onboard camera. Bayesian filter is used for data fusion and convolution neural network for image processing. Field tests resulted in 97% correct detection.
Klíčová slova:
mobile robot; elevator floor determination; Bayesian filtering
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Mobile Robot in the Elevator: What Floor Am i On?
Wheeled mobile robots in multiple stories buildings have to use elevator to access arbitrary floor of the building. To do so, the control system must be able to detect and access elevator controls and ...
Vysokonapěťový pulzní zdroj a řídící jednotka
Gruber, Jan; Janovec, Jiří; Šonský, Jiří; Němec, Tomáš
2022 - český
Zpráva obsahuje popis sestavy vysokonapěťového pulzního zdroje (PPSU) a řídící jednotky (SPCU), které jsou využívány v kombinaci s výbojovou komorou a párem elektrod k aerosolové syntéze nanomateriálů. Uvedena jsou schémata zapojení, seznam elektronických i mechanických součástek, jakožto i popis konektorů a zřetězeného propojení více soustav. Zpráva rovněž obsahuje informace o referenčních parametrech výbojů a popis komunikačního protokolu včetně nastavitelných proměnných. The report contains description of Pulsed Power Source Unit (PPSU) and Spark Control Unit (SPCU), which are utilized in combination with Spark Discharge Chamber and pair of electrodes for aerosol synthesis of nanomaterials. The report includes electronic schematics, list of components, description of connectors and way to chain-link and operate more sets of units. The report also includes information about discharge reference parameters and description of communication protocol and its variables.
Klíčová slova:
electrotechnics; high-voltage; power transformation; pulse generators
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Vysokonapěťový pulzní zdroj a řídící jednotka
Zpráva obsahuje popis sestavy vysokonapěťového pulzního zdroje (PPSU) a řídící jednotky (SPCU), které jsou využívány v kombinaci s výbojovou komorou a párem elektrod k aerosolové syntéze ...
Vibration mode shape extraction of bladed disk
Mekhalfia, Mohammed Lamine; Procházka, Pavel; Tchawou Tchuisseu, Eder Batista; Maturkanič, Dušan; Hodboď, Robert
2022 - anglický
This research paper deals with the experimental protocol followed to visualize the vibration mode shape of an aero-engine bladed disk. This study is based on a comparison between the numerical results obtained through Finite element methods (FEM) using ANSYS software and experimentally using the laser Doppler vibrometer. Therefore the bladed disk was transformed into a 3D virtual environment and structural analysis was performed. The results demonstrate a match between the numerical and the experimental one, this match offers the possibility for using the model for future studies.
Klíčová slova:
blade disk; mode shapes; laser doppler vibrometer
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Vibration mode shape extraction of bladed disk
This research paper deals with the experimental protocol followed to visualize the vibration mode shape of an aero-engine bladed disk. This study is based on a comparison between the numerical results ...
Approaches to dynamical analysis of rotors with parameters of uncertain magnitudes
Zapoměl, Jaroslav; Kozánek, Jan; Košina, Jan; Cibulka, Jan
2022 - anglický
In many cases, the rotor configuration or loading characteristics are described by parameters of uncertain magnitude. Several procedures were developed to analyse such systems. This paper deals with the approach based on application of the fuzzy numbers. The investigated mechanical system is a rotor supported by hydrodynamic bearings. The parameters of its loading have uncertain values.
Klíčová slova:
rotors; uncertain parameters; fuzzy numbers approach
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Approaches to dynamical analysis of rotors with parameters of uncertain magnitudes
In many cases, the rotor configuration or loading characteristics are described by parameters of uncertain magnitude. Several procedures were developed to analyse such systems. This paper deals with ...
Turbine blade linkages in reduced modal synthesis model
Pešek, Luděk; Šnábl, Pavel
2022 - anglický
The paper is the first stage of our modelling turbine blade linkages in reduced modal synthesis model. The modal synthesis method is used for the dynamic behaviour studies of turbine bladed wheels with frictional inter-blade linkages and in case of the microslips the stiffening effect of the linkages play an important role in wheel dynamics. The paper presents the first results of modal analysis of the wheel when springs were used to substitute the linkages in the modal synthesis model.
Klíčová slova:
bladed wheel; reduced model; tie-boss; shroud; stiffening
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Turbine blade linkages in reduced modal synthesis model
The paper is the first stage of our modelling turbine blade linkages in reduced modal synthesis model. The modal synthesis method is used for the dynamic behaviour studies of turbine bladed wheels ...
Annular impinging jets and an active control of hysteretic effects
Devani, Yogendrasasidhar; Antošová, Zuzana; Trávníček, Zdeněk
2022 - anglický
An annular air jet with and without flow control was studied experimentally using flow visualization and measurements of the wall pressure and flow velocity by the Pitot and Prandtl probes and the hot-wire anemometer. To investigate flow control swirling effects, eight synthetic jets were generated from the annular nozzle center body.The experiments cover Reynolds numbers 4000–10000 (evaluated from the outer exit diameter of the annular nozzle). For Re<9000, the bistability and hysteresis were identified and two different flow field patterns (A and B) were found under the same boundary conditions. For A pattern, a small recirculation area (bubble) of separated flow is attached to the nozzle center body. For B pattern, a large recirculation area of separated flow bridges entire nozzle-to-wall distance. For higher Re > 9000, the bistability and hysteresis were not found.Flow control swirling effects causes suppression of the hysteresis. Moreover, weak flow control causes that the entire annular jet is forced into a precessing motion.
Klíčová slova:
annular jet; impinging jet; bistability; hysteresis
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Annular impinging jets and an active control of hysteretic effects
An annular air jet with and without flow control was studied experimentally using flow visualization and measurements of the wall pressure and flow velocity by the Pitot and Prandtl probes and the ...
Aeroacoustic Noise Source Investigation in the Case of the Blade Cascade
Procházka, Pavel P.; Antoš, Pavel; Šnábl, Pavel
2022 - anglický
The blade cascade consisted of five NACA 0010 profiles is examined in the framework of project dealing with nonlinear dynamic phenomenon related to stall flutter of flexible profiles with pitch degree of freedom in subsonic flow. Various angles of attack (AoA) of the cascade generates different (broadband) aeroacoustic noise. The goal of this article is to describe the existence of possible noise sources using two experimental methods – Particle Image velocimetry (PIV) and hot-wire (HW) anemometry.
Klíčová slova:
blade cascade; time-resolved PIV; HW anemometry; FFT
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Aeroacoustic Noise Source Investigation in the Case of the Blade Cascade
The blade cascade consisted of five NACA 0010 profiles is examined in the framework of project dealing with nonlinear dynamic phenomenon related to stall flutter of flexible profiles with pitch ...
Temporal, Spatial, and Spatio-temporal correlation of the velocity fluctuations
Jurčáková, Klára
2022 - anglický
Taylor's hypothesis about frozen turbulence [1] says that if the turbulence intensity is small compared to the mean velocity then the advection of a turbulent flow field past a fixed point can be taken entirely due to the mean flow. This means that in the “frozen turbulent field” spatial and temporal dimensions can be interchanged. Although the main assumption of Taylor's hypothesis is not met in the atmospheric boundary layer (the intensity of turbulence is usually between 10 and 20%) the hypothesis is commonly used to calculate integral length scales of turbulent fields from point measurements. Particle image velocimetry with high temporal resolution (TR-PIV) allows us to analyze both temporal and spatial cross-correlations in the turbulent flow fields and to evaluate obtained results.
Klíčová slova:
frozen turbulence; wind tunnel; integral length scales; Particle Image Velocimetry
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Temporal, Spatial, and Spatio-temporal correlation of the velocity fluctuations
Taylor's hypothesis about frozen turbulence [1] says that if the turbulence intensity is small compared to the mean velocity then the advection of a turbulent flow field past a fixed point can be ...
Analytické postupy řešení kmitání lopatek pro použití u metody Blade Tip Timing - teoretický popis metody
Maturkanič, Dušan; Procházka, Pavel; Mekhalfia, Mohammed Lamine
2022 - český
Práce je zaměřena na analytický přístup k řešení problematiky kmitání lopatek turbíny a kompresoru metodou Blade Tip Timing. Ve zprávě je navržena nová metoda, pro niž byly stanoveny podmínky řešení. Ověření metody bylo provedeno prostřednictvím simulace, kdy byla vyhodnocena spolehlivost, u které byla zadávána správná vstupní data a výpočet probíhal po dostatečně dlouhou dobu, zatímco na základě záměrně zkreslených vstupních dat byla ověřována její přesnost. Součástí zprávy je také vazba výsledků výpočtu frekvence kolísajících otáček, získaných deterministickou metodou, která byla popsána v předchozích pracích, a s nimiž lze dosáhnout přesnějšího výpočtu frekvence a amplitudy kmitání lopatek v reálných podmínkách.\n\n The report focuses on an analytical approach to solving the problem of turbine and compressor blade vibration using the Blade Tip Timing method. The report contains a description of the new method with defined solution requirements. Verification of the method was performed by simulation, where the correct input data was used in the analysis of the reliability of the method when the calculation was repeated at a sufficiently large number of revolutions, while in the accuracy analysis, intentionally distorted input data was used. The report also includes connection to the results of frequency and amplitude calculation for fluctuating speeds obtained by the deterministic method, which was described in previous works aimed at achieving a precise calculation of the frequency and amplitude of blade vibration in real conditions.
Klíčová slova:
vibration; blade; analytical method; frequency; amplitude; turbine; compressor; sensor
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Analytické postupy řešení kmitání lopatek pro použití u metody Blade Tip Timing - teoretický popis metody
Práce je zaměřena na analytický přístup k řešení problematiky kmitání lopatek turbíny a kompresoru metodou Blade Tip Timing. Ve zprávě je navržena nová metoda, pro niž byly stanoveny podmínky řešení. ...
Final Report of the Centre of Excellence for Nonlinear Dynamic Behaviour of Advanced Materials in Engineering
Parma, Slavomír; Gabriel, Dušan
2022 - anglický
This final report presents the CeNDYNMAT Center of Excellence, which was established at the Institute of Thermomechanics of the Czech Academy of Sciences in 2016 and ended in 2022. The report summarizes the most important scientific results of the center. It also gives an overview of the main outcomes and developments of the project, including budgeting, purchasing instrumentation, international cooperation and organization of conferences and summer courses.
Klíčová slova:
nonlinear dynamic behavior; advanced materials; metal plasticity
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Final Report of the Centre of Excellence for Nonlinear Dynamic Behaviour of Advanced Materials in Engineering
This final report presents the CeNDYNMAT Center of Excellence, which was established at the Institute of Thermomechanics of the Czech Academy of Sciences in 2016 and ended in 2022. The report ...
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