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Numerical study of wedge supported oblique shock wave-oblique detonation wave transitions

Pimentel,C. A. R.; Azevedo,J. L. F.; Figueira da Silva,L.F.; Deshaies,B.
Fonte: The Brazilian Society of Mechanical Sciences Publicador: The Brazilian Society of Mechanical Sciences
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2002 EN
Relevância na Pesquisa
56.15%
The results of a numerical study of premixed Hydrogen-air flows ignition by an oblique shock wave (OSW) stabilized by a wedge are presented, in situations when initial and boundary conditions are such that transition between the initial OSW and an oblique detonation wave (ODW) is observed. More precisely, the objectives of the paper are: (i) to identify the different possible structures of the transition region that exist between the initial OSW and the resulting ODW and (ii) to evidence the effect on the ODW of an abrupt decrease of the wedge angle in such a way that the final part of the wedge surface becomes parallel to the initial flow. For such a geometrical configuration and for the initial and boundary conditions considered, the overdriven detonation supported by the initial wedge angle is found to relax towards a Chapman-Jouguet detonation in the region where the wedge surface is parallel to the initial flow. Computations are performed using an adaptive, unstructured grid, finite volume computer code previously developed for the sake of the computations of high speed, compressible flows of reactive gas mixtures. Physico-chemical properties are functions of the local mixture composition, temperature and pressure, and they are computed using the CHEMKIN-II subroutines.

Treatment of chronic plantar fasciitis with extra corporeal shock wave therapy: ultrasonographic morphological aspect and functional evaluation

Androson,Roberto; Apostolico Netto,Alfonso; Macedo,Rafael Rocha; Fasolin,Ricardo Pozzi; Boni,Guilherme; Moreira,Rodrigo Fileto Gavaldao
Fonte: Sociedade Brasileira de Ortopedia e Traumatologia Publicador: Sociedade Brasileira de Ortopedia e Traumatologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
56.05%
Objective: This paper has the purpose to analyze prospectively the treatment results in patients with chronic plantar fasciitis resistant to conservative treatment who underwent extracorporeal shock wave therapy (ESWT). Methods: We evaluated 30 patients (36 feet); 16 (53.3%) patients were male and 14 (47.7%) female with mean age of 48.7 y.o., varying from 33 to 78 y.o.; 16 (53.3%) present the problem on the left side, 14 (46.7%) on the right ones and 6 (20%) bilateral; the symptomatology varied from 6 to 60 months, with the average of 13.58 months. These patients were submitted to a weekly ESWT session for 4 consecutive weeks. We measured the plantar fascia thickness millimeters with ultrasound and we applied American Orthopaedic Foot and Ankle Society (AOFAS) scale for ankle and hindfoot, and Roles & Maudsley scales in pre ESWT, after one, three and six months after and decrease in the plantar fascia thickness by the ultrasound (p = 0.011) along the different moments studied. Results: We observed improvement of the evaluated criteria (p < 0.001) and plantar fascia thickness by ultrasound (p = 0.011) at different time points studied. Conclusion: The ESWT can be considered an important tool in the primary or adjuvant treatment of the chronic plantar fasciitis when associated with conventional therapies. This methodology is safe...

Effect of shock wave reapplication on urinary n-acetyl-beta-glucosaminidase in canine kidney

Fortes,Marco A.Q.R.; Andriolo,Adagmar; Ortiz,Valdemar; Srougi,Miguel
Fonte: Sociedade Brasileira de Urologia Publicador: Sociedade Brasileira de Urologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2004 EN
Relevância na Pesquisa
56.25%
OBJECTIVE: Renal tubular damage can be assessed with the aid of urinary dosing of N-acetyl-beta-glucosaminidase (NAG) and it is possible to demonstrate a significant correlation between shock wave and damage to renal parenchyma. The objective of this study was to assess the effect of shock wave reapplication over urinary NAG in canine kidney. MATERIALS AND METHODS: The authors submitted 10 crossbred dogs to 2 applications of 2000 shock waves in a 24-hour interval in order to assess urinary NAG values after 12, 24, 36 and 48 hours. RESULTS: Twelve hours following the first shockwave application there was an increase in NAG of 6.47 ± 5.44 u/g creatinine (p < 0.05). Twelve hours and 24 h following the second application there was no increase in the urinary enzyme, - 2.56 ± - 7.36 u/g creatinine and 2.89 ± - 7.27 u/g creatinine, respectively (p > 0.05). CONCLUSION: Shock wave reapplication with a 24-hour interval did not cause any increase in urinary NAG.

Extracorporeal shock wave lithotripsy in the treatment of renal pelvicalyceal stones in morbidly obese patients

Mezentsev,V. A.
Fonte: Sociedade Brasileira de Urologia Publicador: Sociedade Brasileira de Urologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2005 EN
Relevância na Pesquisa
56.23%
INTRODUCTION: Management of urolithiasis in morbidly obese patients is usually associated with higher morbidity and mortality compared to non-obese patients. In morbidly obese patients, since the kidney and stone are at a considerable distance from the skin (compared to non-obese patients) difficulty may be found in positioning the patient so that the stone is situated at the focal point of the lithotripter. OBJECTIVE: To evaluate the outcomes and cost-efficiency of extracorporeal shock wave lithotripsy (ESWL) in the treatment of renal pelvicalyceal stones sized between 6 and 20 mm in morbidly obese patients. MATERIALS AND METHODS: Using various aids, such as mobile overtable module, extended shock pathway and abdominal compression 37 patients with body mass index more than 40 kg/m2 were treated using the Siemens Lithostar-plus third generation lithotripter. The size of renal pelvicalyceal stones was between 6 and 20 mm. Treatment costs for shock wave lithotripsy were calculated. RESULTS: The overall stone free rate at 3 months of 73% was achieved. The mean number of treatments per patient was 2.1. The post-lithotripsy secondary procedures rate was 5.4%. No complications, such as subcapsular haematoma or acute pyelonephritis were recorded. The most effective (87% success rate) and cost-efficient treatment was in the patients with pelvic stones. The treatment of the patients with low caliceal stones was effective in 60% only. The cost of the treatment of the patients with low calyceal stones was in 1.8 times higher than in the patients with pelvic stones. CONCLUSION: We conclude that ESWL with the Siemens Lithostar-plus is the most effective and cost-efficient in morbidly obese patients with pelvic stones sized between 6 and 20 mm. 87% success rate was achieved. The increased distance from the skin surface to the stone in those patients does not decrease the success rate provided the stone is positioned in the focal point or within 3 cm of it on the extended shock pathway. ESWL should not be considered as the first line of treatment in the morbidly obese patients with low caliceal stones where the stone was positioned more than 1 cm from the focal point on the extended shock pathway.

Propagation of a Shock Wave in General Relativity: Stationary Approximation

Ishizuka, Toshihisa
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
Relevância na Pesquisa
46.33%
Normal propagation of a shock wave in general relativity through the inhomogeneous gases is considered. Approximation in which the equillibrium medium is devided into infinitesimal layer of a uniform density (the Chisnell-Ôno method) is applied. In general relativity, energy induces a gravitational force and matter deforms space-time. Both these effects are included simply in determining propagation of a shock wave. It is found that the grouwth of strength of the shock wave due to pressure gradient is suppressed compared with the Newtonian case. Both effects have influence on propagation of the shock wave near the surface of a star where shock strength becomes large. However, the effect owing to gravitational field induced by pressure is rather larger than that by deformation of the space-time. As an example propagation of the shock wave in the neutron star is calculated numerically and it is shown that shock strength is estimated to be 10–20% small compared with that in flat space-time.

Experimental investigation of a direct-drive shock wave heated and compressed planar target relevant to ICF

Sawada, Hiroshi (1977 - ); Meyerhofer, David D. ; Regan, Sean P.
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xxi, 147 leaves
ENG
Relevância na Pesquisa
46.39%
Thesis (Ph. D.)--University of Rochester. Dept. of Mechanical Engineering, 2008.; An experimental investigation of shock wave induced heating and compression in planar targets relevant to direct-drive inertial confinement fusion (ICF) was conducted on the OMEGA laser system. A physical understanding of shock wave heating, radiative heating, and heating by energetic electrons in direct-drive ICF is necessary because the achievement of energy gain requires accurate control of the pressure in the main fuel layer. The shock wave provides the dominant heating mechanism. Plasma conditions of a direct-drive shock wave heated and compressed planar plastic target were diagnosed using non-collective, spectrally resolved x-ray scattering and time-resolved x-ray absorption spectroscopy. In the non-collective x-ray scattering experiment, the spatially averaged electron temperature (Te) and average ionization (Z) of the shock wave heated target were inferred from the spectral line shape of the Rayleigh (elastic) and Compton (inelastic) components. Local plasma conditions during shock wave heating and compression as well as the timing of heat front penetration were diagnosed with time-resolved Al 1s-2p absorption spectroscopy of planar plastic foils with a buried layer of Al. The measured Al 1s-2p spectra were analyzed with an atomic physics code PrismSPECT to infer Te and the mass density (ρ) assuming uniform plasma conditions. The experimental results for a variety of square and shaped laser pulse drives were compared with the 1-D hydrodynamics code LILAC using a flux-limited (f = 0.06 and f = 0.1) and a nonlocal thermal transport model. The accuracy of the electron temperatures inferred from the absorption spectroscopy experiment was sufficient to validate the electron thermal transport model in LILAC. The LILAC simulation using the nonlocal model or f = 0.06 accurately predicts the shock wave heating and timing of heat front penetration for square and shaped laser pulses while the shock is transiting the foil. The measured shock wave heating inferred from the x-ray scattering is consistent with the x-ray absorption spectroscopy results. Measurements of the effects of preheat from energetic electrons generated by the two-plasmon-decay instability are inconclusive due to the effects of lateral heat flow in the planar geometry.

Dense Particle Cloud Dispersion by a Shock Wave

Kellenberger, MARK
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
66.34%
High-speed particle dispersion research is motivated by the energy release enhancement of explosives containing solid particles. In the initial explosive dispersal, a dense gas-solid flow can exist where the physics of phase interactions are not well understood. A dense particle flow is generated by the interaction of a shock wave with an initially stationary packed granular bed. The initial packed granular bed is produced by compressing loose aluminum oxide powder into a 6.35 mm thick wafer with a particle volume fraction of 0.48. The wafer is positioned inside the shock tube, uniformly filling the entire cross-section. This results in a clean experiment where no flow obstructing support structures are present. Through high-speed shadowgraph imaging and pressure measurements along the length of the channel, detailed information about the particle-shock interaction was obtained. Due to the limited strength of the Mach 2 incident shock wave, no transmitted shock wave is produced. The initial “solid-like” response of the particle wafer acceleration forms a series of compression waves that coalesce to form a shock wave. Breakup is initiated along the periphery of the wafer as the result of shear that forms due to the fixed boundary condition. Particle break-up starts at local failure sites that result in the formation of particle jets that extend ahead of the accelerating...

"Efeito da terapia por ondas de choque na consolidação óssea após osseossíntese de fêmur com hastes bloqueadas: estudo experimental em cães (canis familiaris)" ; Effect of extracorporeal shock wave therapy one bone healing after femur ostosynthesis with interlocking nails: experimental study in dogs (Canis familiaris)

Bassit, Ana Cristina Ferreira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/09/2004 PT
Relevância na Pesquisa
56.16%
O efeito da terapia por ondas de choque (TOC) na consolidação óssea, após osteotomias bilaterais dos fêmures e osteossínteses com hastes bloqueadas, foi estudado em 8 cães. Os fêmures direitos constituíram o grupo controle e os esquerdos, o grupo tratado, que recebeu 2000 pulsos de ondas de choque de 18 kV, energia de 5mJ (-6dB), na linha da fratura. Radiografias após 4, 8 e 12 semanas, revelaram maior proliferação periosteal no grupo tratado. Os resultados dos exames cintilográficos (razão tratado/controle), realizados na 2a, 4a, 6a, 8a, 10a e 12a semanas, foram estatisticamente superiores no grupo tratado. A TOC provocou aumento da atividade osteogênica na consolidação de fraturas agudas ; The effect of extracorporeal shock wave therapy (ESWT) on bone healing, after bilateral femoral osteotomies and osteosynthesis with interlocking nails, was studied in 8 dogs. The right femurs composed the control group, and the left femurs, the treated group, which received 2000 pulses of shock wave, with 18 kV, 5 mJ (-6dB) energy on the fracture line. Radiographs after 4, 8 and 12 weeks, revealed increased periosteal proliferation in the treated group. The results (treated/control ratio) of the scintigraphic exams, performed on weeks 2...

Focused and Radial Shock Wave Therapy in the Treatment of Tennis Elbow: A Pilot Randomised Controlled Study

Król, Piotr; Franek, Andrzej; Durmała, Jacek; Błaszczak, Edward; Ficek, Krzysztof; Król, Barbara; Detko, Ewa; Wnuk, Bartosz; Białek, Lidia; Taradaj, Jakub
Fonte: Akademia Wychowania Fizycznego w Katowicach Publicador: Akademia Wychowania Fizycznego w Katowicach
Tipo: Artigo de Revista Científica
Publicado em 14/10/2015 EN
Relevância na Pesquisa
46.33%
The purpose of this article was to evaluate and compare the efficacy of radial and focused shock wave therapies applied to treat tennis elbow. Patients with tennis elbow were randomized into two comparative groups: focused shock wave therapy (FSWT; n=25) and radial shock wave therapy (RSWT; n=25). Subjects in the FSWT and RSWT groups were applied with a focused shock wave (3 sessions, 2000 shocks, 4 Hz, 0.2 mJ/mm2) and a radial shock wave (3 sessions, 2000 + 2000 shocks, 8 Hz, 2.5 bar), respectively. The primary study endpoints were pain relief and functional improvement (muscle strength) one week after therapy. The secondary endpoint consisted of the results of the follow-up observation (3, 6 and 12 weeks after the study). Successive measurements showed that the amount of pain patients felt decreased in both groups. At the same time grip strength as well as strength of wrist extensors and flexors of the affected extremity improved significantly. Both focused and radial shock wave therapies can comparably and gradually reduce pain in subjects with tennis elbow. This process is accompanied by steadily improved strength of the affected extremity.

Renal pelvic stones: choosing shock wave lithotripsy or percutaneous nephrolithotomy

Marcovich,Robert; Smith,Arthur D.
Fonte: Sociedade Brasileira de Urologia Publicador: Sociedade Brasileira de Urologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2003 EN
Relevância na Pesquisa
66.2%
Introduction of minimally invasive techniques has revolutionized the surgical management of renal calculi. Extracorporeal shock wave lithotripsy and percutaneous nephrolithotomy are now both well-established procedures. Each modality has advantages and disadvantages, and the application of each should be based on well-defined factors. These variables include stone factors such as number, size, and composition; factors related to the stone's environment, including the stone's location, spatial anatomy of the renal collecting system, presence of hydronephrosis, and other anatomic variables, such as the presence of calyceal diverticula and renal anomalies; and clinical or patient factors like morbid obesity, the presence of a solitary kidney, and renal insufficiency. The morbidity of each procedure in relation to its efficacy should be taken in to account. This article will review current knowledge and suggest an algorithm for the rational management of renal calculi with shock wave lithotripsy and percutaneous nephrolithotomy.

Observations and Interpretation of a Low Coronal Shock Wave Observed in the EUV by the SDO/AIA

Ma, Suli; Raymond, John C.; Golub, Leon; Lin, Jun; Chen, Huadong; Grigis, Paolo; Testa, Paola; Long, David
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 29/06/2011
Relevância na Pesquisa
46.4%
Taking advantage of both the high temporal and spatial resolution of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO), we studied a limb coronal shock wave and its associated extreme ultraviolet (EUV) wave that occurred on 2010 June 13. Our main findings are (1) the shock wave appeared clearly only in the channels centered at 193 \AA and 211 \AA as a dome-like enhancement propagating ahead of its associated semi-spherical CME bubble; (2) the density compression of the shock is 1.56 according to radio data and the temperature of the shockis around 2.8 MK; (3) the shock wave first appeared at 05:38 UT, 2 minutes after the associated flare has started and 1 minute after its associated CME bubble appeared;(4) the top of the dome-like shock wave set out from about 1.23 R\odot and the thickness of the shocked layer is ~ 2\times10^4 km; (5) the speed of the shock wave is consistent with a slight decrease from about 600 km/s to 550 km/s; (6) the lateral expansion of the shock wave suggests a constant speed around 400 km/s, which varies at different heights and directions. Our findings support the view that the coronal shock wave is driven by the CME bubble, and the on-limb EUV wave is consistent with a fast wave or at least includes the fast wave component.; Comment: 24 pages...

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-Lived Radioisotopes with a Shock Wave. II. Varied Shock Wave and Cloud Core Parameters

Boss, Alan P.; Keiser, Sandra A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 01/05/2013
Relevância na Pesquisa
46.35%
A variety of stellar sources have been proposed for the origin of the short-lived radioisotopes that existed at the time of the formation of the earliest Solar System solids, including Type II supernovae, AGB and super-AGB stars, and Wolf-Rayet star winds. Our previous adaptive mesh hydrodynamics models with the FLASH2.5 code have shown which combinations of shock wave parameters are able to simultaneously trigger the gravitational collapse of a target dense cloud core and inject significant amounts of shock wave gas and dust, showing that thin supernova shocks may be uniquely suited for the task. However, recent meteoritical studies have weakened the case for a direct supernova injection to the presolar cloud, motivating us to re-examine a wider range of shock wave and cloud core parameters, including rotation, in order to better estimate the injection efficiencies for a variety of stellar sources. We find that supernova shocks remain as the most promising stellar source, though planetary nebulae resulting from AGB star evolution cannot be conclusively ruled out. Wolf-Rayet star winds, however, are likely to lead to cloud core shredding, rather than to collapse. Injection efficiencies can be increased when the cloud is rotating about an axis aligned with the direction of the shock wave...

Triggering Collapse of the Presolar Dense Cloud Core and Injecting Short-Lived Radioisotopes with a Shock Wave. I. Varied Shock Speeds

Boss, Alan P.; Keiser, Sandra A.; Ipatov, Sergei I.; Myhill, Elizabeth A.; Vanhala, Harri A. T.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 17/11/2009
Relevância na Pesquisa
46.36%
The discovery of decay products of a short-lived radioisotope (SLRI) in the Allende meteorite led to the hypothesis that a supernova shock wave transported freshly synthesized SLRI to the presolar dense cloud core, triggered its self-gravitational collapse, and injected the SLRI into the core. Previous multidimensional numerical calculations of the shock-cloud collision process showed that this hypothesis is plausible when the shock wave and dense cloud core are assumed to remain isothermal at ~10 K, but not when compressional heating to ~1000 K is assumed. Our two-dimensional models (Boss et al. 2008) with the FLASH2.5 adaptive mesh refinement (AMR) hydrodynamics code have shown that a 20 km/sec shock front can simultaneously trigger collapse of a 1 solar mass core and inject shock wave material, provided that cooling by molecular species such as H2O, CO, and H2 is included. Here we present the results for similar calculations with shock speeds ranging from 1 km/sec to 100 km/sec. We find that shock speeds in the range from 5 km/sec to 70 km/sec are able to trigger the collapse of a 2.2 solar mass cloud while simultaneously injecting shock wave material: lower speed shocks do not achieve injection, while higher speed shocks do not trigger sustained collapse. The calculations continue to support the shock-wave trigger hypothesis for the formation of the solar system...

Shock compression of water and solutions of ammonium nitrate

Morley, Michael James
Fonte: University of Cambridge; Department of Physics; Fracture and Shock Physics, Cavendish Laboratory; Trinity College Publicador: University of Cambridge; Department of Physics; Fracture and Shock Physics, Cavendish Laboratory; Trinity College
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
56.1%
Modern mining explosives employ solutions of ammonium nitrate, where the solution is the oxidising component of a fuel/oxidiser mixture. This thesis is primarily concerned with the shock response of water and of aqueous solutions of ammonium nitrate. Of particular interest are the temperatures induced through shock compression. An experimental facility, using a single stage gas gun in the ?plate impact? configuration, is described, along with associated experimental diagnostics. Measurements of, and improvements to, the tilt at impact are reported. The problem of shock temperature is discussed, including a brief review of the relevant literature. It is demonstrated that direct measurement of shock temperature is a complex issue that is not yet fully understood, whereas determination of temperature from an equation of state is an established technique. In a series of experiments, plate impact techniques were utilised to determine the Hugoniot and, through shock/reload experiments, the equation of state of water and aqueous solutions of ammonium nitrate. In-situ manganin gauges were used to measure stresses in the liquids and, from the arrival times of the shock wave, determine the shock velocity. Linear shock velocity?particle velocity Hugoniots for the liquids were determined...

Effect of phase change on shock wave attenuation in GeO2

Liu, C.; Ahrens, T. J.; Brar, N. S.
Fonte: Instituto de Tecnologia da Califórnia Publicador: Instituto de Tecnologia da Califórnia
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 01/06/2002
Relevância na Pesquisa
46.41%
Stress-wave profiles in vitreous GeO2 induced by planar and spherical projectile impact were measured using piezoresistance gauges in the 4 to 18 GPa shock pressure range. The planar experiments demonstrate the response of vitreous GeO2. This response can be divided into three regimes: (1) An elastic shock regime with ramp 4 GPa Hugoniot elastic limit (HEL) precursor. Shock propagation velocity decreases from an initial longitudinal elastic wave speed of 3.5 to 2.8 km/s at 4 GPa. (2) A transition wave regime where the ramp wave is superimposed on the precursor with an additional amplitude of 0 to 2 GPa followed by a sharp increase in shock pressure achieving peak loading pressures of 8 to 14 GPa. Above 4 GPa the ramp wave velocity decreases to a value below 2.5 km/s (the speed of the bulk wave, at the HEL). (3) A shock wave achieving the final shock state forms when peak pressure is >6 GPa specified by linear shock-particle velocity relation D=0.917+1.71 u (km/s) over the 6-40 GPa range for an initial density of 3.655 g/cm(3). The Hugoniots of GeO2 and SiO2, both initially vitreous, are found to be virtually coincident if pressure in SiO2 is calculated by multiplying the GeO2 pressure by the ratio of the initial densities of vitreous GeO2 to fused SiO2. The volume axes are translated by aligning the specific volumes for onset and completion of the four- to six-fold coordination phase change. Although only limited spherical impactor spherically diverging shock experiments were conducted...

Mechanical haemolysis in shock wave lithotripsy (SWL): II. In vitro cell lysis due to shear

Lokhandwalla, Murtuza; McAteer, James A.; Williams, James C., Jr.; Sturtevant, Bradford
Fonte: Instituto de Tecnologia da Califórnia Publicador: Instituto de Tecnologia da Califórnia
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /04/2000
Relevância na Pesquisa
46.34%
In this work we report injury to isolated red blood cells (RBCs) due to focused shock waves in a cavitation-free environment. The lithotripter-generated shock wave was refocused by a parabolic reflector. This refocused wave field had a tighter focus (smaller beam width and a higher amplitude) than the lithotripter wave field, as characterized by a membrane hydrophone. Cavitation was eliminated by applying overpressure to the fluid. A novel passive cavitation detector (HP-PCD) operating at high overpressure (up to 7 MPa) was used to measure acoustic emission due to bubble activity. The typical 'double-bang' emission measured in the lithotripter free-field was replaced by a continuum of weak signals when the fluid was enclosed in a pressure chamber. No acoustic emissions were measured above an overpressure of 5.5 MPa. Aluminium foils were used to study shock wave damage and had distinct deformation features corresponding to exposure conditions, i.e. pitting and denting accompanied by wrinkling. Pitting was eliminated by high overpressure and so was due to cavitation bubble collapse, whereas denting and wrinkling were caused by the reflected shock wave refocused by the parabolic reflector. RBCs suspended in phosphate-buffered saline (PBS) were exposed to the reflected wave field from a parabolic reflector and also from a flat reflector. Exposure to the wave field from the parabolic reflector increased haemolysis four-fold compared with untreated controls and was twice that of cell lysis with the flat reflector. Recently we analysed deformation and rupture of RBCs when subjected to a flow field set up by a focused shock. The cell lysis results presented here are in qualitative agreement with our theoretical prediction that haemolysis is directly related to the gradient of shock strength and validates shearing as a cell lysis mechanism in SWL.

Investigation of the Transmission of a Shock Wave through an Orifice

Monroe, Louis L.
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em 25/09/1958
Relevância na Pesquisa
46.37%
A shock wave propagating in air in a shock tube was reflected from an orifice plate, and the strength or Mach number of the transmitted wave was measured for a range of incident shock Mach numbers from 3 to 9 for several types of orifices. Also schlieren photographs of the starting flow pattern were made for some of the orifices investigated. The measured values of transmitted shock strength are compared with predicted values based on a theoretical one-dimensional flow model for both an ideal gas and a real gas. The agreement between the measured values of transmitted wave Mach number and the theoretically predicted values is extremely good in the Mach number range investigated for a wedge type orifice at an ambient shock tube pressure of 5.0 mm Hg, and also for a conical type orifice at an ambient shock tube pressure of 2.5 mm Hg. For both orifices the ratio of outlet area to inlet area is 7.67. The data also indicate that for a wedge type orifice of area ratio of 23.0 and for a plate (free expansion) type orifice of area ratio 23.0 possible boundary layer and shock wave interactions downstream of the orifice result in measured values of transmitted wave Mach number somewhat greater than that predicted by the one-dimensional flow model. Investigation of the conical orifice with an area ratio 7.67 at a low ambient pressure in the shock tube (0.4 mm Hg) also yields measured values of transmitted wave Mach number greater than that predicted by the one-dimensional flow model...

Determinação da densidade mineral e da elasticidade óssea após a aplicação de ondas de choque extracorpóreas no terceiro metacarpiano de equinos atletas; Mineral density and bone elasticity determination after extracorporeal shock waves application in third metacarpus of athlete equines

Pyles, Marcelo Damas; Fonseca, Brunna Patrícia Almeida da; Machado, Vânia Maria Vasconcelos; Yamada, Ana Lúcia Miluzzi; Alves, Ana Liz Garcia
Fonte: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia Publicador: Universidade de São Paulo. Faculdade de Medicina Veterinária e Zootecnia
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 01/01/2011 POR
Relevância na Pesquisa
56.19%
Objetivou-se neste estudo avaliar os efeitos da aplicação de ondas de choque extracorpóreas (ESWT) no terceiro metacarpiano de equinos hígidos através da determinação da elasticidade óssea. Foram utilizados 20 equinos Puro Sangue Inglês, machos e fêmeas, com dois anos de idade, em início de treinamento e selecionados quanto ao estado de higidez. No início do experimento (D0), todos os animais foram submetidos à avaliação da elasticidade óssea do terceiro metacarpiano. Os animais foram divididos em dois grupos (Grupo Controle - GC e Grupo Experimental - GE). A aplicação das ESWT foi realizada no membro torácico direito dos animais do GE, na região coincidente à da avaliação da elasticidade óssea. Foi utilizado aparelho para terapia de ondas extracorpóreas com densidade de fluxo de energia de 0,15mJ/mm² e 2000 pulsos com probe E6R20, com característica do foco da onda de choque de 20 mm. A ESWT foi repetida a cada 21 dias totalizando três sessões (D0, D21 e D42). A análise da determinação da elasticidade óssea foi realizada no D0, D21, D42 e D72. A média da velocidade ultrassonográfica diferiu entre os grupos no D21, D42 e D72, sendo que os animais do GE apresentaram menor densidade mineral óssea após as aplicações das ESWT. Houve igualmente...

Non-axisymmetric and Steerable Acoustic Field for Enhanced Stone Comminution in Shock Wave Lithotripsy

Lautz, Jaclyn Mary
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2014
Relevância na Pesquisa
66.26%

The primary goal of this dissertation was to assess the feasibility of transforming an electromagnetic (EM) shock wave lithotripter with an acoustic lens as its focusing device from the original axisymmetric pressure distribution to a non-axisymmetric steerable acoustic field. This work was motivated by the desire to better match the distribution of effective acoustic pressure and pulse energy with the trajectory and anatomical features around renal and ureteral calculi during clinical shock wave lithotripsy (SWL). The acoustic field transformation was accomplished by the design of a fan-shaped acoustic barrier (mask) placed on top of the lithotripter acoustic lens to selectively reduce the source aperture along the direction of the barrier axis, therefore effectively broadening the beam width (BW) of the lithotripter field in this preferred direction. Moreover, the geometry of the original lens (L1) was modified so that the acoustic focus of the new lens (L2) at high output voltages (necessitated by the incorporation of the mask) is closely aligned with the lithotripter focus. The mask was further driven by a motor-controlled gear system to rotate around the lithotripter axis, generating a steerable and non-axisymmetric acoustic field. In this dissertation project...

Adaptable Design Improvements For Electromagnetic Shock Wave Lithotripters And Techniques For Controlling Cavitation

Smith, Nathan Birchard
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2012
Relevância na Pesquisa
66.33%

In this dissertation work, the aim was to garner better mechanistic understanding of how shock wave lithotripsy (SWL) breaks stones in order to guide design improvements to a modern electromagnetic (EM) shock wave lithotripter. To accomplish this goal, experimental studies were carefully designed to isolate mechanisms of fragmentation, and models for wave propagation, fragmentation, and stone motion were developed. In the initial study, a representative EM lithotripter was characterized and tested for in vitro stone comminution efficiency at a variety of field positions and doses using phantom kidney stones of variable hardness, and in different fluid mediums to isolate the contribution of cavitation. Through parametric analysis of the acoustic field measurements alongside comminution results, a logarithmic correlation was determined between average peak pressure incident on the stone surface and comminution efficiency. It was also noted that for a given stone type, the correlations converged to an average peak pressure threshold for fragmentation, independent of fluid medium in use. The correlation of average peak pressure to efficacy supports the rationale for the acoustic lens modifications, which were pursued to simultaneously enhance beam width and optimize the pulse profile of the lithotripter shock wave (LSW) via in situ pulse superposition for improved stone fragmentation by stress waves and cavitation...