Backscatter Coefficient Measurements Using a Reference Phantom to Extract Depth-Dependent Instrumentation Factors

1990 ◽  
Vol 12 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Lin Xin Yao ◽  
James A. Zagzebski ◽  
Ernest L. Madsen

In previous work, we demonstrated that accurate backscatter coefficient measurements are obtained with a data reduction method that explicitly accounts for experimental factors involved in recording echo data. An alternative, relative processing method for determining the backscatter coefficient and the attenuation coefficient is presented here. This method involves comparison of echo data from a sample with data recorded from a reference phantom whose backscatter and attenuation coefficients are known. A time domain processing technique is used to extract depth and frequency dependent signal ratios for the sample and the reference phantom. The attenuation coefficient and backscatter coefficient of the sample are found from these ratios. The method is tested using tissue-mimicking phantoms with known scattering and attenuation properties.

1988 ◽  
Vol 10 (4) ◽  
pp. 265-274
Author(s):  
Ping He

This study shows that the amplitude information of ultrasound echoes is carried mainly by the envelope peaks (EPs). It is first shown that the EPs in an A-line represent the maximum number of independent amplitude data. It is then demonstrated that the entire envelope could be approximately reconstructed from the EPs. Finally, using the echo data from a tissue-mimicking phantom, it is found that there are no significant differences among the attenuation coefficients estimated from the EPs, the original envelope samples, and the reconstructed envelope samples. The results of this study indicate that, in the time domain, the attenuation coefficient can be most efficiently estimated from the envelope peaks.


2016 ◽  
Vol 675-676 ◽  
pp. 730-733
Author(s):  
Chumphon Khobkham ◽  
W. Chaiphaksa ◽  
P. Limkitjaroenporn ◽  
P. Prongsamrong ◽  
P. Wiwatkanjana ◽  
...  

In this work, the total mass attenuation coefficient and partial interactions of the zirconium alloy have been calculated by WinXCom program at 1 keV-100 MeV gamma ray energies. Zr2(Fe,Ni) alloys was studied for the mass attenuation coefficients, photoelectric absorption, incoherent, coherent and pair production processes. The effective atomic numbers and electron densities were also calculated. The calculated results show that the total mass attenuation coefficient decreased with increasing of gamma rays energy. The value of total mass attenuation coefficient of each material was different, which depend on chemical compositions of alloy. The partials interactions, effective atomic numbers and electron densities were also calculated and discussed.


Author(s):  
Kota Yamamoto ◽  
Hisashi Asanuma ◽  
Hiroaki Takahashi ◽  
Takafumi Hirata

New data reduction method for isotopic measurements using high-gain Faraday amplifiers enables precise uranium isotopic analysis even from transient signals.


2017 ◽  
Vol 238 ◽  
pp. 234-244 ◽  
Author(s):  
Jianpei Wang ◽  
Shihong Yue ◽  
Xiao Yu ◽  
Yaru Wang

Author(s):  
Isabela M. Nobre ◽  
Julio L. Nicolini ◽  
Joaquim D. Garcia ◽  
Marbey Mosso

2012 ◽  
Vol 8 (1) ◽  
pp. 209-240 ◽  
Author(s):  
Zheng-sheng Zhang,

AbstractThe present paper reports on the findings of a preliminary study of written Chinese, using the Lancaster Corpus of Mandarin Chinese (LCMC, McEnery & Xiao 2004). The first part of the paper introduces the stylistic features, and briefly describes the distributional patterns of these features across the selected written registers. Then, using a multi-feature, multi-dimensional framework (Biber 1988) and the data reduction method of correspondence analysis, three dimensions are identified and interpreted. The study reveals extensive linguistic variation across written Chinese registers, thus complementing previous observations about stylistic differences between spoken and written Chinese. Finally, issues concerning feature selection and dimension interpretation are discussed.


Author(s):  
Majid Jalali

The compounds, Na2B4O7, H3BO3, CdCl2 and NaCl and their solutions, attenuate gamma rays in addition to neutron absorption. These compounds are widely used in shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to saturated solutions of the above four compounds, in energies 1172 keV and 1332 keV have been measured by NaI detector and agree very well with the results obtained by Xcom code. Experiment and computation show that, H3BO3 has the highest gamma ray attenuation coefficient among the aforementioned compounds.


2005 ◽  
Vol 475-479 ◽  
pp. 257-260 ◽  
Author(s):  
Jai Won Byeon ◽  
C.S. Kim ◽  
S.I. Kwun ◽  
S.J. Hong

It was attempted to assess nondestructively the degree of isothermal degradation of 2.25Cr-1Mo steel by using high frequency longitudinal ultrasonic wave. Microstructural parameter (mean size of carbides), mechanical property (Vickers hardness) and ultrasonic attenuation coefficient were measured for the 2.25Cr-1Mo steel isothermally degraded at 630°C for up to 4800 hours in order to find the correlation among these parameters. The ultrasonic attenuation coefficients at high frequencies (over 35MHz) were observed to increase rapidly in the initial 1000 hours of degradation time and then slowly thereafter, while the ones at low frequencies showed no noticeable increase. Ultrasonic attenuation at high frequencies increased as a function of mean size of carbides. Ultrasonic attenuation coefficient was found to have a linear correlation with the hardness, and suggested accordingly as a potential nondestructive evaluation parameter for assessing the mechanical strength reduction of the isothermally degraded 2.25Cr-1Mo steel.


2012 ◽  
Vol 2 (4) ◽  
pp. 136-140
Author(s):  
P. Hema Prabha ◽  
U. Kavya Vaishnavi ◽  
R. Mythili ◽  
M. Lakshmi Kamu ◽  
R. Kanagalakshmi ◽  
...  

Ohmic heating is an emerging technology with large number of actual and future applications. It is an advanced thermal processing method wherein the food material, which serves as an electrical resistor, is heated by passing electricity through it. Like thermal processing, ohmic heating inactivates microorganisms by heat. It can be used for heating liquid foods containing large particulates, heat sensitive liquids and proteinaceous foods. The shelf life of ohmically processed foods is comparable to that of canned and sterile, aseptically processed products. Being an eco‐friendly method it is more effective than conventional thermal processing methods.


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