No (14387)
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14387
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Study of the dispersion of hazardous gas in an underground room.
Nosek, Štěpán
2023 - Czech
This study investigated airflow and pollutant dispersion in an underground room using two different ventilation methods: natural and forced ventilation. The experiment was conducted on a scale model of the room in a wind tunnel using physical modelling. The main objectives were to understand the airflow behaviour and dispersion of passive pollutants in a real environment under isothermal conditions. Tato studie zkoumala proudění vzduchu a šíření polutantů v podzemní místnosti s využitím dvou různých metod ventilace: přirozeného a nuceného větrání. Experiment byl prováděn na zmenšeném modelu místnosti v aerodynamickém tunelu pomocí fyzikálního modelování. Základními cíli bylo porozumět chování proudění vzduchu a rozptylu pasivních polutantů v reálném prostředí za izotermních podmínek.
Keywords:
air pollution; atmospheric boundary layer; indoor; natural ventilation; wind tunnel
Available at various institutes of the ASCR
Study of the dispersion of hazardous gas in an underground room.
This study investigated airflow and pollutant dispersion in an underground room using two different ventilation methods: natural and forced ventilation. The experiment was conducted on a scale model ...
Dynamic loading test of the footbridge for pedestrians and cyclists over the Berounka river in Prague - Radotin after the installation of vibration absorbers
Hračov, Stanislav; Urushadze, Shota
2023 - Czech
The report describes the execution procedure and the results of the dynamic loading test of the pedestrian bridge in Prague Radotín after the installation of vibration absorbers. The vibration level of the bridge deck from pedestrians and runners is compared with the results of a previous dynamic test before the installation of vibration absorbers and is assessed with regard to their comfort and health. Zpráva popisuje postup provedení a výsledky dynamické zatěžovací zkoušky lávky pro pěší v Praze Radotíně po instalaci pohlcovačů kmitů. Úroveň vibrací mostovky lávky od přechodů chodců a běžců je srovnána s výsledky předchozí dynamické zkoušky před instalací pohlcovačů kmitů a je posouzena s ohledem na jejich pohodlí a zdraví.
Keywords:
footbridge; dynamic loading test; pedestrian load; vibration comfort criteria; tuned mass dampers
Available at various institutes of the ASCR
Dynamic loading test of the footbridge for pedestrians and cyclists over the Berounka river in Prague - Radotin after the installation of vibration absorbers
The report describes the execution procedure and the results of the dynamic loading test of the pedestrian bridge in Prague Radotín after the installation of vibration absorbers. The vibration level ...
Annular Impinging Jets and an Active Control of Hysteretic Effects
Devani, Yogendrasasidhar; Antošová, Zuzana; Trávníček, Zdeněk
2023 - English
An annular impinging air jet with and without flow control was studied experimentally using measurements of the wall pressure and flow velocity by the Pitot probe. To investigate flow control swirling effects, eight synthetic jets were generated from the nozzle center body. The experiments cover Reynolds numbers 4000–10,000 (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, B) were found under the same boundary conditions. For higher Re>9000, the hysteresis were not found.
Keywords:
annular jet; impinging jet; hysteresis
Available at various institutes of the ASCR
Annular Impinging Jets and an Active Control of Hysteretic Effects
An annular impinging air jet with and without flow control was studied experimentally using measurements of the wall pressure and flow velocity by the Pitot probe. To investigate flow control swirling ...
Chemical and microstructural analysis of brick samples from the object of Zákupy castle horse stables
Frankeová, Dita; Bauerová, Pavla; Náhunková, Pavla; Ševčík, Radek; Mácová, Petra; Slížková, Zuzana; Vondráčková, Michaela
2023 - Czech
As part of the construction-technical survey, historical brick samples were characterized using thermal analysis (TGA), scanning electron microscopy (SEM/EDS), ion chromatography (IC), infrared spectrometry (FTIR) and physical tests. The results of the tests testify to the good production quality of the masonry elements used. Based on the analyzes carried out, it can be assumed that the observed damage to the bricks is caused by high wetting of the masonry in combination with frost cycles, as well as crystallization cycles of water-soluble salts present in the surface layer of some bricks. V rámci stavebně-technického průzkumu byl provedena charakterizace vzorků historických cihel s využitím termické analýzy (TGA), skenovacího elektronového mikroskopu (SEM/EDS), iontové chromatografie (IC), infračervené spektrometrie (FTIR) a fyzikálních zkoušek. Výsledky zkoušek cihel z objektu Konírna zámku Zákupy svědčí o dobré výrobní kvalitě použitých zdících prvků. Na základě provedených analýz lze předpokládat, že na pozorovaném poškození cihel se podílí vysoké zavlhčení zdiva v kombinaci s mrazovými cykly, a také krystalizační cykly vodorozpustných solí přítomných v povrchové vrstvě některých cihel.
Keywords:
TGA; FTIR; masonry; bricks
Available at various institutes of the ASCR
Chemical and microstructural analysis of brick samples from the object of Zákupy castle horse stables
As part of the construction-technical survey, historical brick samples were characterized using thermal analysis (TGA), scanning electron microscopy (SEM/EDS), ion chromatography (IC), infrared ...
Investigation of basic mechanical and fracture-mechanical properties of specimens cut from high pressure gas pipeline – locality L177/2 after a twentyone months exposition to moist and dry hydrogen at the pressure 3 MPa
Gajdoš, Lubomír; Šperl, Martin; Šorm, Filip; Bejdl, Jan
2023 - Czech
Investigation of the effect of moist and dry hydrogen pressurized to 3 MPa on mechanical and fracture properties of gas pipeline steel ČSN 13126, tensile specimens, Charpy specimens and CT specimens were kept loaded during the exposition in moist hydrogen, after a 21th months exposition it was found that ductility of tensile specimens and fracture parameters Jin and J0,2 of CT specimens decreased whilst the parameter Jm was slightly increased. Vyšetření vlivu vlhkého a suchého vodíku stlačeného na tlak 3 MPa na mechanické a lomové vlastnosti plynovodní oceli ČSN 13126, tahové vzorky, Charpy vzorky i CT vzorky byly během expozice ve vlhkém vodíku trvale zatíženy, po 21 měsících expozice byl zjištěn pokles tažnosti tahových vzorků, pokles lomových parametrů Jin a J0,2 a mírné zvýšení parametru Jm.
Keywords:
stress-strain diagram; Ramberg-Osgood dependence; impact strength; fracture toughness
Available at various institutes of the ASCR
Investigation of basic mechanical and fracture-mechanical properties of specimens cut from high pressure gas pipeline – locality L177/2 after a twentyone months exposition to moist and dry hydrogen at the pressure 3 MPa
Investigation of the effect of moist and dry hydrogen pressurized to 3 MPa on mechanical and fracture properties of gas pipeline steel ČSN 13126, tensile specimens, Charpy specimens and CT specimens ...
Stereolithography for manufacturing of advanced porous solids
Drechslerová, V.; Neuhäuserová, M.; Falta, J.; Šleichrt, J.; Kytýř, Daniel
2023 - English
The aim of this paper is focused on benefits of stereolithography (SLA) technology for the fabrication of the lightweight lattice structures with potential for load-bearing function and high absorption of impact energy. SLA is an additive manufacturing technology employing the principle of liquid resins curing moderated by radiation of a wavelength from ultra-violet band where resulting material parameters are tunable by setting of the curing process. The batches of samples manufactured using three different resins were subjected to quasi-static uni-axial tensile and compression tests. Acquired data were processed to derive deformation behaviour expressed as stress-strain diagrams and fundamental material properties. Based on the knowledge obtained from the mechanical tests, the setup of the fabrication parameters, the most suitable resin for manufacturing of the lattice structures and the overall suitability of SLA technology for the fabrication of advanced porous materials, were determined.
Keywords:
stereolithography; advanced porous materials; quasi-static testing; resin; mechanical characteristics
Available at various institutes of the ASCR
Stereolithography for manufacturing of advanced porous solids
The aim of this paper is focused on benefits of stereolithography (SLA) technology for the fabrication of the lightweight lattice structures with potential for load-bearing function and high ...
Chemical and microstructural analysis of sandstone samples from the cemetery portal at the Gothard in Hořice
Slížková, Zuzana; Frankeová, Dita; Bauerová, Pavla; Náhunková, Pavla; Mácová, Petra; Ševčík, Radek; Vondráčková, Michaela
2023 - Czech
Determination of the chemical and mineralogical composition of the surface layer of sandstone and the speed of water transport through the surface of the stone (comparison of the properties of the light ocher surface and the black surface of sandstone. Stanovení chemického a mineralogického složení povrchové vrstvy pískovce a rychlosti transportu vody povrchem kamene (srovnání vlastností světlého povrchu a černého povrchu pískovce).
Keywords:
sandstone; black film; water absorption; chemical composition; mineralogical composition; stone surface
Available at various institutes of the ASCR
Chemical and microstructural analysis of sandstone samples from the cemetery portal at the Gothard in Hořice
Determination of the chemical and mineralogical composition of the surface layer of sandstone and the speed of water transport through the surface of the stone (comparison of the properties of the ...
Instrumental neutron activation analysis of psychoactive substances, mainly heroin, cocaine, metamphetamine and their adulterants
Kameník, Jan; Kučera, Jan
2023 - Czech
Instrumental neutron activation analysis (INAA) is a robust analytical method theoretically well descibed and understood. INAA works with solid samples, dissolution is not required. The methodology introduces INAA background and lists procedures used for quality control. Protocols for INAA of heroin, cocaine and methamphetamine are described in details. Applications of INAA for psychoactive substances includes estimation of purity and adulterants used and drogs profiling. The metodology is based on measurement of laboratory and real samples. Instrumentální neutronová aktivační analýza je založena na robustním teoretickém základu a umožňuje analýzu vzorků v pevném stavu bez nutnosti jejich převedení do roztoku. Text metodiky zahrnuje představení základů INAA a příklady postupů používaných pro kontrolu přesnosti výsledků. Uveden je popis postupu analýzy heroinu, kokainu a metamfetaminu. Aplikace pro využití INAA zahrnují odhad čistoty a použitých ředících látek a profilování vzorků drog. Metodika je založena na analýze laboratorních a reálných vzorků.
Keywords:
NAA; psychotropic substances; methodology
Available at various institutes of the ASCR
Instrumental neutron activation analysis of psychoactive substances, mainly heroin, cocaine, metamphetamine and their adulterants
Instrumental neutron activation analysis (INAA) is a robust analytical method theoretically well descibed and understood. INAA works with solid samples, dissolution is not required. The methodology ...
Statistical Approach for BTT probes distribution
Mekhalfia, Mohammed Lamine; Procházka, Pavel; Šmíd, R.; Tchawou Tchuisseu, Eder Batista
2023 - English
Blade tip timing (BTT) system is a non-invasive method used for measuring the blade tip timing of rotating machinery. The BTT system typically consists of sensor probes, signal conditioning system, and data acquisition unit. The sensor probes are placed in proximity to the rotating blade tips, Sensors measure the time at which each blade passes by the probe. By measuring the blade tip timing, the BTT system can detect changes in the blade tip vibration, which is an important for the health monitoring and performance optimization of rotating machinery [1]. To ensure accurate measurement of blade tip timing, the probe arrangement is crucial. The placement of the probe relative to the blade tips can affect the measurement accuracy, and thus, several arrangement algorithms have been developed to optimize the placement of the probes. Instead of considering the condition number, a statistical algorithms is followed to optimize the placement of probes for accurate measurement of blade tip timing in turbo-machinery. The statistical approach will be employed to determine the optimal locations for probes, with the aim of reducing errors in the measurement of blade tip timing. \n
Keywords:
blade tip timing principle; RMSE; blade´s dynamics
Available at various institutes of the ASCR
Statistical Approach for BTT probes distribution
Blade tip timing (BTT) system is a non-invasive method used for measuring the blade tip timing of rotating machinery. The BTT system typically consists of sensor probes, signal conditioning system, ...
SMV-2023-19: Development of welding and brazing joints for special industrial fittings
Zobač, Martin; Vlček, Ivan; Dupák, Libor; Rončák, Ján; Zobačová, Jitka
2023 - Czech
This project aims to find the optimal technological procedure for welding and brazing of thermal inserts in an automatic steam condensate drain. This project builds on previous research and efforts in the field. It builds on previous work and aims to improve the manufacturing and maintenance process of steam condensate removal equipment by using new welding and brazing processes for thermal liners. Cílem tohoto projektu je najít optimální technologický postup pro svařování a pájení termických vložek v automatickém odváděči parního kondenzátu. Tento projekt staví na předchozím výzkumu a snahách v oboru. Navazuje na předchozí práci a má za cíl zdokonalit proces výroby a údržby zařízení pro odvádění parního kondenzátu pomocí nových postupů svařování a pájení termických vložek.
Keywords:
electron beam welding; vacuum brazing
Available at various institutes of the ASCR
SMV-2023-19: Development of welding and brazing joints for special industrial fittings
This project aims to find the optimal technological procedure for welding and brazing of thermal inserts in an automatic steam condensate drain. This project builds on previous research and efforts in ...
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