نتایج جستجو برای: ultrasonic focusing

تعداد نتایج: 125732  

Journal: :گوارش 0
fariborz mansour-ghanaei ahmad alizadeh zahra pourrasouli hamid vahidi mohammadreza naghipour farahnaz joukar

background: ultrasonography is an imaging method which, due to its relative economy, is becoming more widely available in regions of the world where fasciola hepatica infection occurs most frequently. in this report, we describe the sonographic findings of hepatic lesions in patients with fascioliasis to help confirmation of the sonographic characteristics of this disease and thus aid in its di...

2014
Hong Wei Peng Yu Jie Cheng Zhi Guo Hu Chu Chen Zhang

This document presents the principle of ultrasonic distance measurement is described, the main error sources of ultrasonic distance measurement are analyzed also. A method of improving precision of ultrasonic distance measurement in air, in which the transmission speed of ultrasonic wave if corrected by measured air temperature and the forward edge of receive wave can be determined accurately b...

2014
Dong Xinyuan

Aiming at the problem that echo signal is hard to recognize caused by ultrasonic energy’s overquick dispersion and attenuation, a kind of ultrasonic horn is designed. According to the acoustic theory analysis, the ultrasonic horn can increase its radiation energy by improving impedance matching. The ultrasonic horn can make the directivity of sound source sharper and energy more centralized bec...

Journal: :iranian journal of oil & gas science and technology 2014
behnam keshavarzi mohammad javad shojaei mohammad hossein ghazanfari cyrus ghotbi

it has been proved that ultrasonic energy can considerably increase the amount of oil recovery in animmiscible displacement process. although many studies have been performed on investigating theroles of ultrasonic waves, based on the best of our knowledge, little attention has been paid to evaluatewave attenuation parameter, which is an important parameter in the determination of the energydel...

Journal: :international journal of energy and environmental engineering 2010
r ebrahimi h ghasemzadeh mohammadi r safdari ahmadabad m rahmani

continuous exposure to high-energy ultrasonic waves depolymerises macromolecules in solutions and produces a permanent reduction in viscosity. different factors affect the efficiency of this ultrasonic depolymerisation. in this work ultrasonic degradation of one commercially important hydrogel based on acrylic acid and acrylamide was carried out in aqueous solution at room temperature (25oc). a...

2012
Xiaoyan Zhuang Yijiu Zhao Zhijian Dai Houjun Wang Li Wang

This study presents a compressed sensing (CS) based sampling approach for repetitive ultrasonic signal. Proposed system considers recovering ultrasonic signal with high equivalent sampling frequency from samples captured using analog-to-digital converter (ADC) clocked at a rate lower than Nyquist rate. A basis function is constructed to realize ultrasonic signal sparse representation, which pav...

2013
Zhihong FENG Changyun MIAO Hua BAI Yanli YANG

The optimization problem of ultrasonic testing instrument is studied in this paper. Using ultrasonic nondestructive testing technology to detect quality of products or parts, because the function of conventional ultrasonic testing instruments is custom-built and defined by manufacturers, it is very difficult to meet ever-changing testing requirements such as testing accuracy, testing efficiency...

2014
Giovanni Durando Claudio Guglielmone Chiara Magnetto

HIFU power measurement At ultrasonic laboratory of INRIM (Istituto Nazionale di Ricerca Metrologica) it is possible to measure the ultrasonic power emitted by HIFU (High Intesity Focused Ultrasound) transducers. Two different measuring systems for the determination of ultrasonic power have been developed. Both systems are based on the radiation force balance method. The first system is based on...

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