نتایج جستجو برای: ultrasonic oscillation
تعداد نتایج: 66673 فیلتر نتایج به سال:
in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...
Article history: Received on: 09/03/2013 Accepted on: 07/05/2013 Available online: 30/05/2013 Paris fargesii is a famous Chinese traditional medicinal plant used as antipyretic, antidotal, antiphlogistic and analgesic. This research aimed at the determination of the total polysaccharides contents in P. fargesii, which were collected from Baoxing country of Sichuan Province in order to get the o...
In general the ultrasonic testing is used for flaw detection and localization in tested materials. Flaws in materials are commonly characterized in measured ultrasonic signals by faults echoes. Ultrasonic signals measured on materials with coarse grained structure contain relative high level of noise. This undesirable part of ultrasonic signal should be reduced to make the fault echo detection ...
We propose a practical map representation termed rheology mapping for comprehensively evaluating the dependence of viscoelasticity on applied shear deformation and timescale represented by oscillation frequency, utilizing ultrasonic spinning rheometry, which has excellent applicability to wide variety polymer solutions. The was two typical kinds One is carboxymethyl cellulose (CMC) aqueous solu...
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...
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...
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...
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...
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...
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...
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