نتایج جستجو برای: cavitation

تعداد نتایج: 7504  

Journal: :Journal of experimental botany 2002
Volker Stiller John S Sperry

"Cavitation fatigue" is the increased susceptibility of a xylem conduit to cavitation as a result of its prior cavitation. It was investigated whether cavitation fatigue induced in vivo could be repaired in intact plants. Sunflowers (Helianthus annuus L.) were subjected to soil drought in the greenhouse. Native embolism and vulnerability to cavitation was measured in well-watered controls and a...

2004
Zhenhuan Liu

To model the processes of cavitation inception, noise and damuge, it is necessaty to generate a model of the cavitation event rate which can then be coupled with the consequences of the individual events to produce a complete synthesis of thephenomenon. In this paper we describe recent efforts to connect the observed event rates to the measured distributions of cavitation nuclei in the oncoming...

2012
Toshio Nakamura Oscar Lopez-Pamies

This paper proposes an effective numerical method to study cavitation instabilities in non-linear elastic solids. The basic idea is to examine—by means of a 3D finite element model—the mechanical response under affine boundary conditions of a block of non-linear elastic material that contains a single infinitesimal defect at its center. The occurrence of cavitation is identified as the event wh...

Journal: :Stroke 2010
Gillian M Potter Fergus N Doubal Caroline A Jackson Francesca M Chappell Cathie L Sudlow Martin S Dennis Joanna M Wardlaw

BACKGROUND AND PURPOSE On brain imaging, lacunes, or cerebrospinal fluid-containing cavities, are common and are often counted in epidemiological studies as old lacunar infarcts. The proportion of symptomatic lacunar infarcts that progress to lacunes is unknown. Noncavitating lacunar infarcts may continue to resemble white matter lesions. METHODS We identified patients with acute lacunar stro...

Journal: :Ultrasound in medicine & biology 2004
David Melodelima Jean Yves Chapelon Yves Theillère Dominique Cathignol

In the high-intensity focused ultrasound (US), or HIFU, field, it is well-known that the cavitation effect can be used to induce lesions of larger volume. The principle is based on the increase in the equivalent attenuation coefficient of the tissue in the presence of the bubbles created by cavitation. The elementary lesions produced by combination of cavitation and thermal effects, using focus...

2011
Karsten Opitz Eberhard Schlücker Oliver Schade

Owing to their impressive properties reciprocating positive displacement pumps are used in many applications. Pumping fluids at high delivery pressures and metering are the areas of frequent use. The design of reciprocating pumps requires an exact knowledge of the appearing phenomena such as unacceptable pipeline pulsation and harmful cavitation. But cavitation in reciprocating positive displac...

2015
D Fernandez Rivas B Verhaagen Andres Galdamez Perez Elena Castro-Hernandez Ralph van Zwieten Karin Schroen

We introduce a Cavitation Intensifying Bag as a versatile tool for acoustic cavitation control. The cavitation activity is spatially controlled by the modification of the inner surface of the bag with patterned pits of microscopic dimensions. We report on different measurements such as the transmission of ultrasound, temperature increase inside the bag during sonication. Several applications of...

Journal: :Ultrasonics sonochemistry 2009
Bernhard Felver David C King Simon C Lea Gareth J Price A Damien Walmsley

Ultrasonic scalers are used in dentistry to remove calculus and other contaminants from teeth. One mechanism which may assist in the cleaning is cavitation generated in cooling water around the scaler. The vibratory motion of three designs of scaler tip in a water bath has been characterised by laser vibrometry, and compared with the spatial distribution of cavitation around the scaler tips obs...

2011
Christopher E. Brennen

In many cavitating liquid flows, when the number and concentration of the bubbles exceeds some critical level, the flow becomes unsteady and large clouds of cavitating bubbles are periodically formed and then collapse when convected into regions of higher pressure. This phenomenon is known as cloud cavitation and when it occurs it is almost always associated with a substantial increase in the c...

2017
Vandiver Chaplin Charles F Caskey

BACKGROUND Mild-hyperthermia therapy (40-45 °C) with high-intensity focused ultrasound (HIFU) is a technique being considered in a number of different treatments such as thermally activated drug delivery, immune-stimulation, and as a chemotherapy adjuvant. Mechanical damage and loss of cell viability associated with HIFU-induced acoustic cavitation may pose a risk during these treatments or may...

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