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Tytuł:
The acoustic excitation of newly-formed bubbles
Autorzy:
Deane, G.
Czerski, H.
Stokes, D.
Powiązania:
https://bibliotekanauki.pl/articles/331506.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
gas bubbles
hydroacoustics
natural frequency
Opis:
Gas bubbles in water act as oscillators with a natural frequency inversely proportional to their radius and a quality factor determined by thermal, radiation, and viscous losses. Newly-formed gas bubbles are excited into breathing mode oscillations immediately after creation, causing them to radiate a pulse of sound. Although the linear dynamics of spherical gas bubbles are well-understood, the mechanism driving the sound production has not been unambiguously identified. Using bubbles released from a nozzle as a model system, it can be shown that sound production is consistant with the rapid change in volume associated with the collapse of an air neck formed immediately after bubble pinch-off. The model is able to adequately describe the production of sound by bubbles released from a nozzle, and can also explain some of the acoustic properties of bubbles fragmenting in fluid turbulence. Laboratory experiments and model calculations of the mechanism are presented. [Work supported by ONR and NSF].
Źródło:
Hydroacoustics; 2008, 11; 71-78
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Towards field measurement of populations of methane gas bubbles in marine sediment: an inversion method required for interpreting two-frequency insonification data from sediment containing gas bubbles
Autorzy:
Leighton, T.
Mantouka, A.
White, P.
Klusek, Z.
Powiązania:
https://bibliotekanauki.pl/articles/331678.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
methane
marine sediment
gas bubbles
Opis:
This paper describes a key stage in the process for developing a new device for the measurement of gas bubbles in sediment. The device is designed to measure gas bubble populations within the top 2 m of marine sediments, and has been deployed at inter-tidal sites along the South coast of England. Acoustic techniques are particularly attractive for such purposes because they can be minimally invasive. However they suffer from the limitation that their results can be ambiguous. Therefore it is good practice to deploy more than one acoustic technique at time. The new device does just this, but it is designed with the practical economy that the task is accomplished with the minimum number of transducers. One of the measurement techniques relies on insonifying the sediment with two frequencies. This paper outlines how the bubble size distribution is inferred through inversion of the signals detected when two frequencies are projected into the sediment. The high attenuation of the sediment makes this interpretation far more difficult that it would be in water. This paper outlines these difficulties and describes how they can be overcome.
Źródło:
Hydroacoustics; 2008, 11; 203-224
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pęcherzyki w szkliwie mołdawitów
Bubbles in moldavite glass
Autorzy:
Brachaniec, Tomasz
Szczyrba, Mirosław
Powiązania:
https://bibliotekanauki.pl/articles/1032995.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Meteorytowe
Tematy:
bubbles
gas
moldavite
pressure
tektites
Opis:
Bubbles in tektites can be formed by several different mechanisms. A review of published data has shown that the gas pressure in the bubbles is generally low. Composition of the contained gases published in most articles sharply differs from the composition of the terrestrial atmosphere.
Źródło:
Acta Societatis Metheoriticae Polonorum; 2014, 5; 17-20
2080-5497
Pojawia się w:
Acta Societatis Metheoriticae Polonorum
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Method of determining the volume of forming gas bubbles
Autorzy:
Rząsa, M.
Czapla, B.
Powiązania:
https://bibliotekanauki.pl/articles/114470.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
image analysis
gas bubbles
measurement volume
Opis:
The paper presents a method of determining the volume of gas bubble formation. This issue is important because of the choice of parameters in the processes of mass exchange between gas and liquid. The idea of measurement method is based on filming the formation of gas bubbles, and on this basis is made image analysis process. These papers describe the steps relevant the separation of gas bubble image and calculations of its volume. In addition a sample researches have conducted, for whom defined the uncertainty of measurement. Analysis of the results determined the boundary intervals, at which a change in the pattern forming bubbles occurs, which results in that the diameter of the bubbles formed strongly depends on the gas stream emerging from the nozzle.
Źródło:
Measurement Automation Monitoring; 2015, 61, 2; 35-38
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Odrywanie się pęcherzy gazowych od krawędzi dysz badania eksperymentalne i modelowanie
The gas bubbles detachment from the nozzl experimental investigations and modeling
Autorzy:
Mosdorf, R.
Wyszkowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/386352.pdf
Data publikacji:
2010
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
modelowanie
pęcherze gazowe
modelling
gas bubbles
Opis:
W pracy przedstawiono wyniki badań eksperymentalnych generowania pęcherzy powietrza z dyszy o wewnętrznej średnicy równej 1.1mm. Rejestrowano zmiany ciśnienia powietrza, czasy przejścia pęcherzy przez wiązkę światła laserowego oraz dynamikę zmiany kształtu pęcherza z zastosowaniem kamery do szybkich zdjęć. Do modelowania odrywania się pęcherzy zastosowano układ równań różniczkowych zwyczajnych opisujący zmiany masy powietrza w układzie zasilania dyszy. W trakcie symulacji, podobnie jak w czasie eksperymentu, obserwowano chaotyczne zmiany parametrów opisujących odrywanie się pęcherzy. Uzyskane wyniki symulacji pozwalają sformułować hipotezę, że jednym z powodów występowania zjawiska chaotycznego odrywania się pęcherzy gazowych jest nieliniowy charakter oddziaływania pęcherza na ciecz wywołany sprężaniem gazu zawartego w pęcherzach o kształcie sferycznym oraz układzie zasilania dyszy w gaz.
The result of experimental investigations of bubbles emission from brass nozzle with inner diameter equal to 1.1mm has been presented. The air pressure, time of passing bubbles through laser beam and dynamics of bubbles deformation have been simultaneously recorded. The bubbles detachment from the nozzle has been modelled using the set of ODE which describes the spring interaction between gas bubble and liquid. In the model and experiment the chaotic behaviours of bubbles have been observed. The obtained results can be summarized as follows: the chaotic behaviours of bubbles detachment from the nozzle can be caused by non-linear character of interaction between liquid and the system consisting of spherical bubble and air supply system.
Źródło:
Acta Mechanica et Automatica; 2010, 4, 1; 72-79
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Dynamics of Liquid Movement Inside the Nozzle During the Bubble Departures for Low Air Volume Flow Rate
Autorzy:
Dzienis, P.
Mosdorf, R.
Wyszkowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/386993.pdf
Data publikacji:
2012
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
pęcherze gazowe
analiza nieliniowa
bubbles
nonlinear analysis
Opis:
The main aim of investigation was to analyze the influence of liquid movement inside the nozzle on the dynamics of bubble departure. Dynamics of such process decides about the periodic and aperiodic bubble departures. During the experiment it has been simultaneously recorded: changes of the depth of the nozzle penetration by liquid, air pressure and shape of bubble trajectory directly over the nozzle (in the length of 30 mm). The air volume flow rate was in the range 0.00632 - 0.0381 l/min. There has been shown that for all air volume flow rates the time periods with periodic and aperiodic bubble departures have been occurred. Duration of these intervals varies with the air volume flow rate. It has been found that the aperiodic bubble departures begin when the time of bubble growth increases. The changes of maximum values of liquid position inside the nozzle are associated with changes of the shape of bubble trajectories. There has been shown that straightens of the trajectory precedes the appearance of periodical or aperiodic time period of bubble departures. The aperiodic bubble departures are accompanied by a significant deviation of bubble trajectory from a straight line. The correlation dimension analysis shown that three independent variables are enough to describe the behaviour of liquid movement inside the nozzle. These independent variables may be: liquid velocity, liquid position in the nozzle and gas pressure in the nozzle.
Źródło:
Acta Mechanica et Automatica; 2012, 6, 3; 31-36
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency and non-linear analysis of bubble paths in bubble chain
Autorzy:
Mosdorf, R.
Wyszkowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/386552.pdf
Data publikacji:
2010
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
analiza
pęcherze gazowe
interakcja
analysis
bubbles
interaction
Opis:
In the paper the paths of bubbles emitted from the bras nozzle with inner diameter equal to 1.1 mm have been analyzed. The mean frequency of bubble departure was in the range from 1 to 36 Hz. Bubble paths have been recorded using a high speed camera. The image analysis technique has been used to obtain the bubble paths for different mean frequencies of bubble departures. The Fourier, wavelet analysis and recurrence plots have been used to determine the strength of interac- tion between bubbles in column. It has been found that the influence of previously departing bubbles on trajectory of next bubble in the column can be significant for fb > 30 Hz, in this case the bubble paths become less periodic and more instable. In this case the distance between subsequent departing bubbles (S/D) becomes close to 1. It causes that the vertical interaction between departing bubbles is enough strong to change the dynamical properties of bubble paths.
Źródło:
Acta Mechanica et Automatica; 2010, 4, 4; 71-77
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of salinity on the underwater noise generated by small scale air entrainment events
Autorzy:
Szuszkiewicz, J.
Klusek, Z.
Gorska, N.
Powiązania:
https://bibliotekanauki.pl/articles/332616.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
underwater noise
air entrainment
bubbles
bubble clusters
Opis:
Some part of the energy released in the wave breaking process is transformed into the energy of the noise. This sound depends on the water properties, however, there is a lack of reliable data concerning the underwater noise generated by less energetic events. The aim of this study was to understand the impact of salinity on the underwater noise produced during small scale air entrainment events, typical for low wind speed conditions. The tipping trough experiment was performed in a small tank to generate the small scale air injections. Four, linearly placed hydrophones HTI-96-MIN were used to record the acoustic noise accompanying this phenomenon. The bubble plume development, and underwater noise spectra, were compared for salty and fresh water. The potential energy of the modeled events resulted in different spectra, and salinity played an essential role in the emitted underwater noise.
Źródło:
Hydroacoustics; 2017, 20; 167-172
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heat load and deuterium plasma effects on SPS and WSP tungsten
Autorzy:
Vilémová, M.
Matějíček, J.
Nevrlá, B.
Chernyshova, M.
Gasior, P.
Kowalska-Strzeciwilk, E.
Jäger, A.
Powiązania:
https://bibliotekanauki.pl/articles/146910.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
tungsten
fusion
heat loading
irradiation
bubbles
surface damage
Opis:
Tungsten is a prime choice for armor material in future nuclear fusion devices. For the realization of fusion, it is necessary to address issues related to the plasma–armor interactions. In this work, several types of tungsten material were studied, i.e. tungsten prepared by spark plasma sintering (SPS) and by water stabilized plasma spraying (WSP) technique. An intended surface porosity was created in the samples to model hydrogen/ helium bubbles. The samples were subjected to a laser heat loading and a radiation loading of deuterium plasma to simulate edge plasma conditions of a nuclear fusion device (power density of 108 W/cm2 and 107 W/cm2, respectively, in the pulse intervals up to 200 ns). Thermally induced changes in the morphology and the damage to the studied surfaces are described. Possible consequences for the fusion device operation are pointed out.
Źródło:
Nukleonika; 2015, 60, 2; 275-283
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
INNOWACJE I ICH WPŁYW NA ROZWÓJ NADZORU KORPORACYJNEGO
Innovations and their influence on the development of corporate governance
Autorzy:
Jerzemowska, Magdalena
Powiązania:
https://bibliotekanauki.pl/articles/950879.pdf
Data publikacji:
2014
Wydawca:
Wydawnictwo Uniwersytetu Ekonomicznego we Wrocławiu
Tematy:
bubbles
financial innovation
conversion
public debt
corporate governance
Opis:
The aim of the paper is to present the argument that there is not one way of assessing the impact of innovations on corporate governance system. The analysis reveals that the three early speculative bubbles – Tulipmania (Holland, 1637) the South Sea Bubble (England, 1720) and the Mississippi Company Bubble (France, 1720) − were caused in great part by financial innovations. The rapid development of the economies, financial institutions and instruments, accounting practices and corporations was not matched by the parallel development of appropriate laws, financial and accounting infrastructure and corporate governance. The three scandals (and the 2008 as well) also reflected the lack of effective methods of protection against corruption and financial market fraud.
Źródło:
Financial Sciences. Nauki o Finansach; 2014, 1(18); 49-65
2080-5993
2449-9811
Pojawia się w:
Financial Sciences. Nauki o Finansach
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identyfikacja przepływu pęcherzyków powietrza za pomocą tomografii optycznej : przegląd metod
Identification of air bubble flow with optical tomography : a review of methods
Autorzy:
Rząsa, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2070960.pdf
Data publikacji:
2010
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
pęcherzyki powietrza
tomografia optyczna
air bubbles
optical tomography
Opis:
W pracy charakteryzowano trzy metody wyznaczania parametrów pęcherzyków gazu poruszających się w cieczy. Metody pomiarowe oparte są na tomografii optycznej. W zwięzły sposób omówiono zasadę działania, a następnie zwrócono na wady i zalety tych rozwiązań. Podano przykładowe wyniki badań oraz odniesiono się do zakresu stosowalności omówionych metod. W podsumowaniu zwrócono uwagę na istotne elementy będące pomocne przy wyborze optymalnej metody pomiarowej w zastosowaniu do badanego procesu.
The paper presents three methods for the determination of parameters of gas bubbles moving in liquid. The measuring methods are based on optical tomography. Advantages and disadvantages of technical solutions are described. Exemplary test results are given and a range of their applicability is defined. Finally, a special attention was taken to select a proper measurement method for the process tested.
Źródło:
Inżynieria i Aparatura Chemiczna; 2010, 2; 107-108
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Perturbations of the depth of liquid penetration into the capillary during bubble departures
Autorzy:
Dzienis, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/2112920.pdf
Data publikacji:
2021
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
bubbles
bubble departure
liquid movement into the capillary
Opis:
In the present paper, the influence of bubble size on liquid penetration into the capillary was experimentally and numerically studied. In the experiment, bubbles were generated from a glass capillary (with an inner diameter equal to 1 mm) in a glass tank containing distilled water, tap water or an aqueous solution of calcium carbonate. These liquids differ in the value of their surface tension, which influences the bubble size. During experimental investigations, air pressure fluctuations in the gas supply system were measured. Simultaneously, the videos showing the liquids’ penetration into the capillary were recorded. Based on the videos, the time series of liquid movements inside the capillary were recovered. The numerical models were used to study the influence of bubble size on the velocity of liquid flow above the capillary and the depth of liquid penetration into the capillary. It was shown that the air volume flow rate and the surface tension have the greatest impact on the changes of pressure during a single cycle of bubble departure (Δp). The changes in pressure during a single cycle of bubble departure determine the depth of liquid penetration into the capillary. Moreover, the values of Δp and, consequently, the depth of liquid penetration can be modified by perturbations in the liquid velocity above the capillary outlet.
Źródło:
Acta Mechanica et Automatica; 2021, 15, 4; 254--259
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gone with the Wind? Early Medieval Central Places in Today’s Rural Areas. Between Research, Preservation and Re-Enactment: An Introduction
Autorzy:
Florkiewicz, Iwona
Wołoszyn, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/960021.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Rzeszowski. Instytut Archeologii Uniwersytetu Rzeszowskiego. Muzeum Okręgowe w Rzeszowie
Tematy:
public archaeology
re-Enactment,
nationalism
information cocoons
filter bubbles
Opis:
The article presents remarks on the social context of archaeology. Its high cost and permanent presence in public space mean that the functioning of archaeology (much more than other disciplines, such as historical studies) depends on the current political situation. Our discipline was a source of entertainment for the elites (the Middle Ages), a form of legitimising monarchy (the Early Modern Era), and a building block of national pride (the 19th–20th c.). Contrary to what we initially hoped for, the Internet, which has been gaining in popularity since the end of the last century, has brought more control than freedom and enables – for the first time on this scale – creating closed-off communities that hold radical views, which are sometimes absurd in the eyes of science. This is also the case of notions about the past, an excellent Polish example of which is the theory of Great Lechia. The popularity of this myth and the fact that fake archaeology was constructed around it is proof that the past is very far from being gone with the wind, and the need to reconstruct it is also present in our – so very post-modern – world. All this warrants an attempt to reflect on the way in which notions about the past are created by archaeologists, including those who work away from great centres of civilisation
Źródło:
Analecta Archaeologica Ressoviensia; 2018, 13; 11-32
2084-4409
Pojawia się w:
Analecta Archaeologica Ressoviensia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rational Speculative Bubbles in the Fine Wine Investment Market
Autorzy:
Czupryna, Marcin
Oleksy, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/630092.pdf
Data publikacji:
2015
Wydawca:
Szkoła Główna Handlowa w Warszawie
Tematy:
rational speculative bubbles, fine wine, wine investment, wine exchange
Opis:
The paper focuses on detection of rational speculative bubbles in fine wineinvestment market. Our research was conducted using recursive tests. The chosenmethod additionally allowed us to set time frames for potential bubbles. Theresults have shown that speculative bubble episodes appeared between 2006–2007both in fine wine market and in most of selected traditional stock exchanges.However, only the fine wine market recorded the second wave of speculativebubbles between 2010–2011.
Źródło:
Kwartalnik Kolegium Ekonomiczno-Społecznego Studia i Prace; 2015, 3, 3; 159-172
2082-0976
Pojawia się w:
Kwartalnik Kolegium Ekonomiczno-Społecznego Studia i Prace
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zbyt długo utrzymywane zbyt niskie stopy procentowe NBP zagrożeniem dla bezpieczeństwa finansowego Polaków i rozwoju gospodarczego Polski
The Polish National Bank’s Interest Rates Kept Too Low for Far Too Long: A Threat to the Financial Security of Poles and the Economic Development of Poland
Autorzy:
Redo, Magdalena
Powiązania:
https://bibliotekanauki.pl/articles/2146957.pdf
Data publikacji:
2022-04-20
Wydawca:
Uniwersytet Mikołaja Kopernika w Toruniu. Wydawnictwo UMK
Tematy:
interest rates
monetary policy
dept
financial imbalances
speculative bubbles asset bubbles
stopy procentowe
polityka pieniężna
zadłużenie
nierównowagi finansowe
bańki spekulacyjne
Opis:
Narzędzia polityki gospodarczej generują różnorakie skutki – nie tylko te pożądane i łatwo dostrzegalne. Dlatego zwłaszcza w przypadku Polski, gospodarki nadrabiającej dystans rozwojowy do państw Zachodu, ważne są umiejętności analitycznego myślenia i korzystanie z doświadczeń nie tylko własnej polityki gospodarczej, by nie popełniać błędów, których można było uniknąć, i zapobiec tym samym obniżeniu bezpieczeństwa finansowego polskiego społeczeństwa i pogorszeniu poziomu jego życia w nadchodzących dekadach. NBP, utrzymując zbyt długo zbyt niskie stopy procentowe, wzmaga nie tylko presję inflacyjną w Polsce, ale również przyczynia się do pogłębiania problemu nadmiernego zadłużenia (nie tylko) gospodarstw domowych w Polsce w relacji do poziomu zamożności i zdolności kredytowej. Obniża tym samym bezpieczeństwo finansowe Polski i Polaków. Dlatego tak istotne jest, by bank centralny w XXI w., zgodnie z opiniami rosnącej liczby ekspertów, zapewniał szerzej rozumianą stabilność finansową – a nie pilnował jedynie inflacji – i przeciwdziałał nierównowagom finansowym.
Economic policy tools generate various effects – not only the desired and easily perceived ones. That is why, especially in the case of Poland, which is an economy that is catching up with the developmental gap with Western countries, it is so important to have analytical thinking skills and to use the experience of not only own economic policy, so as not to make mistakes that could have been avoided and thus prevent the reduction of the financial security of Polish society and the deterioration of its standard of living in the coming decades. By keeping interest rates too low for far too long, the Polish National Bank not only increases the inflationary pressure in Poland, but also contributes to the deepening of the problem of excessive indebtedness (not only) of households in Poland in relation to their level of wealth and creditworthiness. That is why it is so important that the central bank in the 21st century – according to the opinions of a growing number of experts – should ensure a broader financial stability, rather than just keeping an eye on inflation and counteracting financial imbalances.
Źródło:
Historia i Polityka; 2022, 39 (46); 137-156
1899-5160
2391-7652
Pojawia się w:
Historia i Polityka
Dostawca treści:
Biblioteka Nauki
Artykuł
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