82 resources related to Bubble Clouds
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IEEE International Conference on Plasma Science (ICOPS) is an annual conference coordinated by the Plasma Science and Application Committee (PSAC) of the IEEE Nuclear & Plasma Sciences Society.
The International Conference on Robotics and Automation (ICRA) is the IEEE Robotics and Automation Society’s biggest conference and one of the leading international forums for robotics researchers to present their work.
The conference program will consist of plenary lectures, symposia, workshops and invitedsessions of the latest significant findings and developments in all the major fields of biomedical engineering.Submitted papers will be peer reviewed. Accepted high quality papers will be presented in oral and postersessions, will appear in the Conference Proceedings and will be indexed in PubMed/MEDLINE
To promote awareness, understanding, advancement and application of ocean engineering and marine technology. This includes all aspects of science, engineering, and technology that address research, development, and operations pertaining to all bodies of water. This includes the creation of new capabilities and technologies from concept design through prototypes, testing, and operational systems to sense, explore, understand, develop, use, and responsibly manage natural resources.
OCEANS 2020 - SINGAPORE
An OCEANS conference is a major forum for scientists, engineers, and end-users throughout the world to present and discuss the latest research results, ideas, developments, and applications in all areas of oceanic science and engineering. Each conference has a specific theme chosen by the conference technical program committee. All papers presented at the conference are subsequently archived in the IEEE Xplore online database. The OCEANS conference comprises a scientific program with oral and poster presentations, and a state of the art exhibition in the field of ocean engineering and marine technology. In addition, each conference can have tutorials, workshops, panel discussions, technical tours, awards ceremonies, receptions, and other professional and social activities.
Broad coverage of concepts and methods of the physical and engineering sciences applied in biology and medicine, ranging from formalized mathematical theory through experimental science and technological development to practical clinical applications.
Theory, concepts, and techniques of science and engineering as applied to sensing the earth, oceans, atmosphere, and space; and the processing, interpretation, and dissemination of this information.
Imaging methods applied to living organisms with emphasis on innovative approaches that use emerging technologies supported by rigorous physical and mathematical analysis and quantitative evaluation of performance.
A journal covering Microsensing, Microactuation, Micromechanics, Microdynamics, and Microelectromechanical Systems (MEMS). Contains articles on devices with dimensions that typically range from macrometers to millimeters, microfabrication techniques, microphenomena; microbearings, and microsystems; theoretical, computational, modeling and control results; new materials and designs; tribology; microtelemanipulation; and applications to biomedical engineering, optics, fluidics, etc. The Journal is jointly sponsored by the IEEE Electron Devices ...
Bayes procedures; buried-object detection; dielectric measurements; Doppler measurements; geomagnetism; sea floor; sea ice; sea measurements; sea surface electromagnetic scattering; seismology; sonar; acoustic tomography; underwater acoustics; and underwater radio communication.
2009 IEEE International Ultrasonics Symposium, 2009
Histotripsy is a non-invasive ultrasound therapy which utilizes cavitation clouds to mechanically fractionate tissue. The mechanism by which bubble clouds form is important to understand the histotripsy process. We used high speed imaging with frame rates between 0.1-10 million fps to observe the progression of cloud formation. A 1 MHz spherically-focused transducer was used to apply single histotripsy pulses to ...
2017 IEEE International Ultrasonics Symposium (IUS), 2017
Vessel occlusions caused by blood clots can result in severe cardiovascular diseases such as ischemic stroke and deep vein thrombosis (DVT). The current treatment standard for DVT is anticoagulation therapy, which does little to address long term morbidity as opposed to approaches directed at removing clots. High intensity ultrasound can rapidly and non-invasively resolve clots by generating bubble clouds that ...
IEEE Journal of Oceanic Engineering, 2001
High-frequency propagation close to an active surf line is explored with 12and 100-kHz propagation paths together with measurements of bubble clouds, bubble size distributions, and waves. Breaking waves inject massive bubble plumes that are mixed downwards from the roller region by intense turbulence. If these injections follow one another at intervals less than the time taken for the bubbles to ...
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, 2014
In this paper, we report a gas flow phenomenon induced by ultrasonic water cavitation and capillary wave in a vibrating hollow tip and reflector system. The cavitation clouds generated a gas suction force and the capillary wave created tunnels through which the gas could go into the liquid. The gas flow rate was measured and compared under different conditions, including ...
IEEE Journal of Oceanic Engineering, 2007
One of the underlying assumptions in the effective medium theory describing the propagation of acoustic waves through bubble clouds is that the probability of an individual bubble being located at some position in space is independent of the locations of other bubbles. However, bubbles within naturally occurring clouds may be influenced by the dynamics of the fluids in which they ...
Trust Management in Edge Clouds with SCONE - IEEE Future Networks Webinar
Group on Earth Observations(GEOSS): Technology
IMS 2015: Chris Walker - John Tucker Special Tribute - SuperCam: A 64 Pixel SIS Receiver Array for Submillimeter-wave Astronomy
Cafe: Cloud Appliances for Enterprises
Panel: Ethics in AI - Impacts of (Anti?) Social Robotics - VIC Summit 2019
Histotripsy is a non-invasive ultrasound therapy which utilizes cavitation clouds to mechanically fractionate tissue. The mechanism by which bubble clouds form is important to understand the histotripsy process. We used high speed imaging with frame rates between 0.1-10 million fps to observe the progression of cloud formation. A 1 MHz spherically-focused transducer was used to apply single histotripsy pulses to optically-transparent gelatin tissue phantoms, with peak negative pressure of 19 MPa and 5-50 cycles. Dense bubble clouds were observed to first form at a distal position within the focus, and grow proximally towards the transducer, opposite the ultrasound propagation direction. Growth began from the site of single cavitation bubbles. Based on these observations, it was hypothesized that the shocked waveforms from histotripsy pulses scatter from single bubbles, which invert the shock and induce a large negative pressure in its vicinity. To test this hypothesis, the positive incident shock pressure was reduced without significantly affecting the negative pressure. When the peak positive pressure was lowered, the likelihood and size of bubble clouds initiating at the focus was greatly reduced. These results suggest that the positive pressure of the incident waveform is important for generating bubble clouds in histotripsy.
Vessel occlusions caused by blood clots can result in severe cardiovascular diseases such as ischemic stroke and deep vein thrombosis (DVT). The current treatment standard for DVT is anticoagulation therapy, which does little to address long term morbidity as opposed to approaches directed at removing clots. High intensity ultrasound can rapidly and non-invasively resolve clots by generating bubble clouds that erode them. However, lack of appropriate methods for treatment monitoring is a limiting factor in its widespread adoption. The objective of this work was to assess the capabilities of passive imaging as a monitoring tool during clot lysis using a near ideal receiver array geometry.
High-frequency propagation close to an active surf line is explored with 12and 100-kHz propagation paths together with measurements of bubble clouds, bubble size distributions, and waves. Breaking waves inject massive bubble plumes that are mixed downwards from the roller region by intense turbulence. If these injections follow one another at intervals less than the time taken for the bubbles to rise to the surface, acoustic signals will be continuously blocked, forming an acoustical barrier that effectively inhibits any propagation. Occasionally, waves break seaward of this barrier. In this case, dense bubble clouds are mixed down beneath the air entrainment zone, but there is sufficient time for them to disappear before succeeding breakers, allowing intermittent high-frequency propagation recharge the bubble field. The duration and shape of signal dropouts are then determined by the selective removal of bubbles by buoyancy and dissolution. In addition to turbulence created by the air entrainment process, a lower level of continuous background turbulence may be generated by interaction of residual currents with the wave boundary layer. Our observations illustrate the variable character of acoustic blocking by bubble clouds and serve as a basis for quantitative analysis of these effects with a 2D propagation model coupled to 2D models of bubble cloud evolution and background turbulence.
In this paper, we report a gas flow phenomenon induced by ultrasonic water cavitation and capillary wave in a vibrating hollow tip and reflector system. The cavitation clouds generated a gas suction force and the capillary wave created tunnels through which the gas could go into the liquid. The gas flow rate was measured and compared under different conditions, including applied power, type of reflector, and tip-to-reflector distance. A model was proposed to explain the mechanisms of the gas flow and analyze the results in the experiments.
One of the underlying assumptions in the effective medium theory describing the propagation of acoustic waves through bubble clouds is that the probability of an individual bubble being located at some position in space is independent of the locations of other bubbles. However, bubbles within naturally occurring clouds may be influenced by the dynamics of the fluids in which they are entrained so that they become preferentially concentrated, or clustered, leading to statistical dependence in their positions. For bubble clouds in which the important scattering terms include those with interactions between at least two bubbles, statistical dependence between bubble positions leads to a reduction in the attenuation of the coherent acoustic pressure field from that which would be predicted for a nonclustered bubble cloud. Bubble clustering can be accommodated in effective medium theories using correlation functions describing the relationship between the positions of the bubbles. For double scattering, the two-bubble correlation (i.e., the pair correlation function) must be used, for triple scattering, the three bubble correlation must be used, and so on. In contrast to the three attenuation of the coherent field, making the assumption of independent bubble positions leads to an underestimate of the incoherent field. Both the coherent and incoherent acoustic fields for bubble clouds exhibiting correlated bubble positions are explored in this paper with the use of numerical simulations.
Our investigations have shown that short (les50 musec) high intensity, low duty cycle ultrasound pulses can achieve significant breakdown of tissue structure at a tissue-fluid interface and in bulk soft tissue. We call this technique "histotripsy", and inertial cavitation is its hypothesized mechanism. To understand the physical basis of histotripsy, a high speed camera was used to image hypothesized bubble clouds generated by ultrasound pulses. The results show the following: (1) Ultrasound pulses generated a bubble cloud both at a tissue-water interface and inside a gel used to mimic the bulk soft tissue. This bubble cloud plays an important role in the histotripsy process; (2) An ultrasound pulse of several musec long can generate a bubble cloud lasting for several hundreds of musec; and (3) the intensity threshold to initiate a bubble cloud is lower at a gel-water interface than inside a gel
When modeling sound propagation through the uppermost layers of the ocean, the presence of bubble clouds cannot be ignored. Their existence can convert a range-independent sound propagation problem into a range-dependent one. Measurements show that strong changes in sound speed and attenuation are produced by the presence of swarms of microbubbles which can be depicted as patchy clouds superimposed on a very weak background layer. While models suitable for use in acoustic calculations are available for the homogeneous bubble layer (which results from long time averages of the total bubble population), no similar parameterizations are available for the more realistic inhomogeneous bubble layer. Based on available information and within the framework of a classification scheme for bubble plumes proposed by Monahan, a model for the range and depth dependence of the bubbly environment is developed to fill this void. This model, which generates a possible realization of the bubbly environment, is then used to calculate the frequency-dependent change in the sound speed and attenuation induced by the presence of the bubble plumes. Time evolution is not addressed in this work.
The radiation and scattering from micro-bubble clouds with volume fractions greater than .01% are described using a theoretical model and measured data. In the low frequency limit, the radiation and scattering of sound was determined to be monopole when in the free field. The natural frequency of the cloud is predicted by a modified Minnaert equation. The measured backscatter target strength is consistent with theoretical expectations. These results show that both the production of sound by breaking waves and sea surface scattering is affected by these micro-bubble clouds and plumes either in whole or in part. Since these features are acoustically compact at the lower frequencies, a multipole expansion shows that the most important response is the monopole and its surface image.
By means of an effective equation model for the propagation of pressure waves in a bubbly liquid, the normal modes of oscillation of regions of bubbly liquid in an otherwise pure liquid are calculated for some simple geometries. It is shown that the frequencies of oscillation of such bubble clouds can be much lower than those of the constituent bubbles in isolation and fall well within the range where substantial wind-dependent noise is observed in the ocean. A comparison with some experimental data strongly supports the theoretical results.<<ETX>>
Our recent studies have demonstrated that mechanical fractionation of tissue structure with sharply demarcated boundaries can be achieved using short (< 20 mus), high intensity ultrasound pulses delivered at low duty cycles. We have called this technique histotripsy. Histotripsy has potential clinical applications where noninvasive tissue fractionation and/or tissue removal are desired. The primary mechanism of histotripsy is thought to be acoustic cavitation, which is supported by a temporally changing acoustic backscatter observed during the histotripsy process. In this paper, a fast-gated digital camera was used to image the hypothesized cavitating bubble cloud generated by histotripsy pulses. The bubble cloud was produced at a tissue-water interface and inside an optically transparent gelatin phantom which mimics bulk tissue. The imaging shows the following: 1) Initiation of a temporally changing acoustic backscatter was due to the formation of a bubble cloud; 2) The pressure threshold to generate a bubble cloud was lower at a tissue-fluid interface than inside bulk tissue; and 3) at higher pulse pressure, the bubble cloud lasted longer and grew larger. The results add further support to the hypothesis that the histotripsy process is due to a cavitating bubble cloud and may provide insight into the sharp boundaries of histotripsy lesions.
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