INVESTIGATION PARAMETERS ULTRASONIC DEVICE ON PHASED ARRAYS. FOCUSING MODES FOR ULTRASONIC DEVICE TYPE OF OMNISCAN

2021 ◽  
pp. 24-35
Author(s):  
V. Yu. Titov
Keyword(s):  
Phased Arrays ◽  
Near Field ◽  
Signal Amplitude ◽  
Drill Hole ◽  
Flaw Detector ◽  
Amplitude Dependence ◽  
Large Variability ◽  
Ultrasonic Device ◽  
Families Of Curves ◽  
Significant Difference

The article is devoted to possibilities of regular focusing of Omniscan device on phased arrays. Questions are raised about evaluation of testing results when using linear and sector scan-ning with different focus parameters. The question of size near-field for phased arrays and asso-ciated choice of focus mode is discussed. The article is based on experiments conducted on samples with artificial reflectors at the same size, but different in type: a non-directional reflector (a side-drill hole) and a directional reflector (a flat-bottomed reflector), located at the same depth. The study was conducted for transducers with different frequencies. Families of curves of the signal amplitude dependence are obtained: on depth reflector, on focus depth setting, and on type reflector. The results emphasize need for precise focusing with-in the near-field of the transducer for small thicknesses or shallow depth of occurrence of discontinuities, and large variability in choice of focusing for depths in far-field. The study notes a significant difference in values of depth reflector at different focusses at a fixed position of transducer. In this article, in addition to considering possibility of focusing a flaw detector with phased arrays, the focus is on interpretation of results and reliability of testing in the analysis and comparison data. An integral part of the technological testing protocol for phased array is the depth of focus and the type of scanning. The obtained data do not depend on the frequency of transducer, which means that conclusions are applicable to general range of flaw detectors on phased arrays.

scholarly journals Prediction of low-voltage areas using modified APPLE score

EP Europace ◽  
2020 ◽  
Author(s):  
Timm Seewöster ◽  
Falco Kosich ◽  
Philipp Sommer ◽  
Livio Bertagnolli ◽  
Gerhard Hindricks ◽  
...  
Keyword(s):  
Low Voltage ◽  
Area Under The Curve ◽  
Signal Amplitude ◽  
Left Ventricular ◽  
Left Ventricular Ejection ◽  
Ventricular Ejection Fraction ◽  
Receiver Operating Characteristic Curves ◽  
Density Maps ◽  
Significant Difference ◽  
Study Population

Abstract Aims The presence of low-voltage areas (LVAs) in patients with atrial fibrillation (AF) reflects left atrial (LA) electroanatomical substrate, which is essential for individualized AF management. However, echocardiographic anteroposterior LA diameter included into previous LVAs prediction scores does not mirror LA size accurately and impaired left ventricular ejection fraction (LV-EF) is not directly associated with atrial myopathy. Therefore, we aimed to compare a modified (m)APPLE score, which included LA volume (LAV) and LA emptying fraction (LA-EF) with the regular APPLE score for the prediction of LVAs. Methods and results In patients undergoing first AF catheter ablation, LVAs were determined peri-interventionally using high-density maps and defined as signal amplitude <0.5 mV. All patients underwent cardiovascular magnetic resonance imaging before intervention. The APPLE (one point for Age ≥ 65 years, Persistent AF, imPaired eGFR ≤ 60 mL/min/1.73 m2, LA diameter ≥ 43 mm, and LVEF < 50%) and (m)APPLE (last two variables changed by LAV ≥ 39 mL/m2, and LA-EF < 31%) scores were calculated at baseline. The study population included 219 patients [median age 65 (interquartile range 57–72) years, 41% females, 59% persistent AF, 25% LVAs]. Both scores were significantly associated with LVAs [OR 1.817, 95% CI 1.376–2.399 for APPLE and 2.288, 95% CI 1.650–3.172 for (m)APPLE]. Using receiver operating characteristic curves analysis, the (m)APPLE score [area under the curve (AUC) 0.779, 95% CI 0.702–0.855] showed better LVAs prediction than the APPLE score (AUC 0.704, 95% CI 0.623–0.784), however, without statistically significant difference (P = 0.233). Conclusion The modified (m)APPLE score demonstrated good prognostic value for LVAs prediction and was comparable with the regular APPLE score.

Planar Near-Field Measurement of Digital Phased Arrays Using Near-Field Scan Plane Reconstruction

2012 ◽  
Vol 60 (6) ◽  
pp. 2711-2718 ◽  
Author(s):  
Andrew E. Sayers ◽  
W. Mark Dorsey ◽  
Kenneth W. O'Haver ◽  
John A. Valenzi
Keyword(s):  
Field Measurement ◽  
Phased Arrays ◽  
Near Field ◽  
Near Field Measurement

Capacitive wireless powering for electric vehicles with near-field phased arrays

2017 ◽  
Author(s):  
Jose Estrada ◽  
Sreyam Sinha ◽  
Brandon Regensburger ◽  
Khurram Afridi ◽  
Zoya Popovic
Keyword(s):  
Electric Vehicles ◽  
Phased Arrays ◽  
Near Field ◽  
Wireless Powering

Palatal Soft Tissue Thickness at Different Ages Using an Ultrasonic Device

2012 ◽  
Vol 36 (4) ◽  
pp. 405-409 ◽  
Author(s):  
SM Lee ◽  
JH Park ◽  
M Bayome ◽  
HS Kim ◽  
SS Mo ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Repeated Measures ◽  
Permanent Dentition ◽  
Mixed Dentition ◽  
Tissue Thickness ◽  
Ultrasonic Device ◽  
Irregularity Index ◽  
Soft Tissue Thickness ◽  
Significant Difference ◽  
And Gender

Objective: To evaluate the palatal soft tissue thickness among placement sites of temporary anchorage devices (TADs) in late mixed, early permanent and permanent dentition. Materials and Method: The sample consisted of three groups; 42 late mixed dentition (mean age = 11.0 years), 41 early permanent dentition (mean age = 13.8 years), and 38 permanent dentition (mean age = 23.1 years). Soft tissue thickness was measured intraorally with an ultrasonic device using a grid of 27, 4x4 mm2 squares to delineate the measurement points. Repeated measures analysis of variance was performed to analyze the data. Results: There was a significant difference in soft tissue thickness among dentition groups with the permanent dentition group showing the highest values (P < 0.001). In each group, the thickness significantly increased from median to lateral and from anterior to posterior sites. Furthermore, the thickness showed a significant difference according to the arch form and gender (P < 0.05). However, there were no significant differences according to irregularity index and Angle classification. Conclusions: The soft tissue thickness of the palate increases from the late mixed to permanent dentition. These findings may be helpful for clinicians to enhance their successful application of TADs in the palate.

31P NMR quantitation of phosphorus metabolites in rat heart and skeletal muscle in vivo

2001 ◽  
Vol 281 (2) ◽  
pp. H882-H887 ◽  
Author(s):  
Sam Hitchins ◽  
Julie M. Cieslar ◽  
Geoffrey P. Dobson
Keyword(s):  
Skeletal Muscle ◽  
Rat Heart ◽  
Signal Amplitude ◽  
Phosphorus Compounds ◽  
External Reference ◽  
Significant Difference ◽  
External Standard ◽  
Phosphorus Metabolites ◽  
Tissue Phosphorus

The aim of this study was to examine two methods of 31P NMR quantitation of phosphocreatine (PCr), ATP, and Pi in rat heart and skeletal muscle in vivo. The first method employed an external standard of phenylphosphonic acid (PPA; 10 mM), and the second method used an enzymatic measurement of tissue ATP equated to the area under the βATP peak. With the use of the external standard, the concentrations of ATP, PCr, and Pi in the rat heart were 4.48 ± 0.33, 9.21 ± 0.65, and 2.25 ± 0.16 μmol/g wet wt, respectively. With the use of the internal ATP standard, measured on the same tissue, the contents (means ± SE) were 4.78 ± 0.19, 9.83 ± 0.18, and 2.51 ± 0.33 μmol/g wet wt, respectively ( n = 7). In skeletal muscle, ATP, PCr, and Pi were 6.09 ± 0.19, 23.44 ± 0.88, and 1.81 ± 0.18 μmol/g wet wt using the PPA standard and 6.03 ± 0.19, 23.30 ± 1.30, and 1.82 ± 0.19 μmol/g wet wt using the internal ATP standard ( n = 6). There was no significant difference for each metabolite as measured by the two methods of quantification in heart or skeletal muscle. The results validate the use of an external reference positioned symmetrically above the coil and imply that each has similar NMR sensitivities (similar signal amplitude per mole of 31P between PPA and tissue phosphorus compounds). We conclude that PCr, ATP, and Pi are nearly 100% visible in the normoxic heart and nonworking skeletal muscle given the errors of measurement.

Matched Gaussian Apodization of Pulsed Acoustic Phased Arrays

1980 ◽  
Vol 2 (4) ◽  
pp. 338-369 ◽  
Author(s):  
Andre J. Duerinckx
Keyword(s):  
Cross Section ◽  
Phased Array ◽  
Phased Arrays ◽  
Near Field ◽  
Homogeneous Medium ◽  
Short Pulses ◽  
Time Space ◽  
Acoustic Beams ◽  
Strong Focusing ◽  
Matching Concept

Gaussian apodization weighting functions matched to the time delay distribution for focusing of phased arrays are introduced. The matching concept is based upon the theory of eigenmodes of freely propagating acoustic beams with a finite cross-section. The effect of this matched gaussian apodization on the beam cross-section is analysed for several acoustic phased array configurations generating acoustic wavefronts in a weakly attenuating and homogeneous medium. A strength of focusing parameter is introduced. The relation between apodization parameters and the strength of focusing is analyzed and illustrated. For strong focusing the parameters of the gaussian matched apodization become independent of the focal range. A simulator was developed which allows the study of acoustic pressure waves in the near-field and far-field generated by a linear phased array excited with short pulses. The simulator provides 2-D and 3-D representations of acoustic wave fronts generated by a pulsed phased array, illustrating the effects of apodization for pulsed acoustic beams in the time-space domain.

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