Characterization of cavitation-radiated acoustic power using single-element detectors

2017 ◽  
Vol 141 (5) ◽  
pp. 3551-3551
Author(s):  
Kyle T. Rich ◽  
T. Douglas Mast
Keyword(s):  
Acoustic Power ◽  
Single Element

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

scholarly journals Characterization of cavitation-radiated acoustic power using diffraction correction

2018 ◽  
Vol 144 (6) ◽  
pp. 3563-3574 ◽  
Author(s):  
Kyle T. Rich ◽  
Christy K. Holland ◽  
Marepalli B. Rao ◽  
T. Douglas Mast
Keyword(s):  
Acoustic Power ◽  
Diffraction Correction

MEMS Pressure Sensor Array for Aeroacoustic Analysis of the Turbulent Boundary Layer

2008 ◽  
Author(s):  
Joshua S. Krause ◽  
Robert D. White ◽  
Mark J. Moeller ◽  
Judith M. Gallman ◽  
Richard De Jong
Keyword(s):  
Pressure Sensor ◽  
Sensor Array ◽  
Single Element ◽  
Lumped Element ◽  
Depth Analysis ◽  
Fluid Damping ◽  
Sensitivity Studies ◽  
Gain Stage ◽  
Acoustic Sensitivity

The design, fabrication, and characterization of a surface micromachined, front-vented, 64 channel (8×8), capacitively sensed pressure sensor array is described. The array was fabricated using the MEMSCAP PolyMUMPs® process, a three layer polysilicon surface micromachining process. An acoustic lumped element circuit model was used to design the system. The results of our computations for the design, including mechanical components, environmental loading, fluid damping, and other acoustic elements are detailed. Theory predicts single element sensitivity of 1 mV/Pa at the gain stage output in the 400–40,000 Hz band. A laser Doppler velocimetry (LDV) system has been used to map the spatial motion of the elements in response to electrostatic excitation. A strong resonance appears at 480 kHz for electrostatic excitation, in good agreement with mathematical models. Static stiffness measured electrostatically using an interferometer is 0.1 nm/V2, similar to the expected stiffness. Preliminary acoustic sensitivity studies show single element acoustic sensitivity (as a function of frequency) increasing from 0.01 mV/Pa at 200 Hz to 0.16 mV/Pa at 2 kHz. A more in depth analysis of acoustic sensitivity is ongoing.

DESIGN AND FABRICATION OF A 20 MHz ANNULAR ARRAY FOR MEDICAL ULTRASOUND

2012 ◽  
Vol 05 (01) ◽  
pp. 1150010
Author(s):  
ZHENHUA HU ◽  
JUE PENG
Keyword(s):  
Focal Point ◽  
Impedance Matching ◽  
Center Frequency ◽  
Depth Of Field ◽  
Single Element ◽  
Medical Ultrasound ◽  
Annular Array ◽  
Array Transducer ◽  
Small Depth

Most high frequency (> 15 MHz) medical ultrasound systems are based on single element transducers mechanically scanned. These systems can provide images with excellent resolution. However, single element transducers are often limited by the fixed focal point and small depth of field. Annular arrays consisting of concentric rings of elements are focused electronically. These arrays are desirable to avoid the fixed focal point of the single element transducers and improve the depth of field. This paper reports the design, fabrication, and characterization of a 5-element equal-area annular array transducer. After electrical impedance matching, the average center frequency was 20 MHz and -6 dB bandwidths ranged from 34 to 42%. The ILs for the matched annuli ranged from 6.1 to 26.5 dB.

Design and Characterization of Capacitive Micromachined Ultrasonic Transducer

2006 ◽  
Vol 321-323 ◽  
pp. 132-135
Author(s):  
Bong Young Ahn ◽  
Ki Bok Kim ◽  
Hae Won Park ◽  
Young Joo Kim ◽  
Yong Seok Kwak
Keyword(s):  
Sacrificial Layer ◽  
Ultrasonic Transducer ◽  
Medical Engineering ◽  
Single Element ◽  
Air Atmosphere ◽  
Engineering Society ◽  
Capacitive Micromachined Ultrasonic Transducer ◽  
X 32 ◽  
2D Array

As cMUTs (capacitive Micromachined Ultrasonic Transducer) offer numerous advantages over traditional transducers in terms of efficiency, bandwidth, and cost, they are expected to replace piezoelectric transducers in many applications. In particular, 2D-array cMUTs have aroused great interest in the medical engineering society because of their ability to materialize a true volumetric ultrasonic image. In this study, single element cMUTs with 32 x 32 and 64 x 64 cells were successfully fabricated. The diameter and thickness of the membrane are 35 and 1000 nm, respectively, with a sacrificial layer thickness of 600 nm. The electric characteristics of the fabricated cMUT were measured. Tests on the efficiencies of the cMUT in terms of wave generation and in terms of detection according to the bias and pulse voltage were performed in an air atmosphere.

scholarly journals On solvable groups with one vanishing class size

2020 ◽  
pp. 1-20
Author(s):  
M. Bianchi ◽  
E. Pacifici ◽  
R. D. Camina ◽  
Mark L. Lewis
Keyword(s):  
Conjugacy Class ◽  
Finite Groups ◽  
Class Size ◽  
Single Element ◽  
Conjugacy Class Sizes ◽  
Conjugacy Class Size ◽  
Odd Order ◽  
Vanishing Elements ◽  
A Finite Group

Let G be a finite group, and let cs(G) be the set of conjugacy class sizes of G. Recalling that an element g of G is called a vanishing element if there exists an irreducible character of G taking the value 0 on g, we consider one particular subset of cs(G), namely, the set vcs(G) whose elements are the conjugacy class sizes of the vanishing elements of G. Motivated by the results inBianchi et al. (2020, J. Group Theory, 23, 79–83), we describe the class of the finite groups G such that vcs(G) consists of a single element under the assumption that G is supersolvable or G has a normal Sylow 2-subgroup (in particular, groups of odd order are covered). As a particular case, we also get a characterization of finite groups having a single vanishing conjugacy class size which is either a prime power or square-free.

Fabrication and characterization of nanolayered single element nitride coating

2015 ◽  
Vol 284 ◽  
pp. 112-117 ◽  
Author(s):  
Y.H. Yang ◽  
K.Y. Liu ◽  
Y.X. Qiu ◽  
C.H. Wu ◽  
F.B. Wu
Keyword(s):  
Single Element ◽  
Nitride Coating ◽  
Fabrication And Characterization

scholarly journals In vitro and in vivo characterization of a cranial window prosthesis for diagnostic and therapeutic cerebral ultrasound

2020 ◽  
pp. 1-13
Author(s):  
Francesco Prada ◽  
Andrea Franzini ◽  
Shayan Moosa ◽  
Frederic Padilla ◽  
David Moore ◽  
...  
Keyword(s):  
Acoustic Power ◽  
Acoustic Properties ◽  
Single Element ◽  
Swine Model ◽  
Water Tank ◽  
Cranial Window ◽  
Resonance Frequencies ◽  
Ultrasound Energy

OBJECTIVEThe authors evaluated the acoustic properties of an implantable, biocompatible, polyolefin-based cranial prosthesis as a medium to transmit ultrasound energy into the intracranial space with minimal distortion for imaging and therapeutic purposes.METHODSThe authors performed in vitro and in vivo studies of ultrasound transmission through a cranial prosthesis. In the in vitro phase, they analyzed the transmission of ultrasound energy through the prosthesis in a water tank using various transducers with resonance frequencies corresponding to those of devices used for neurosurgical imaging and therapeutic purposes. Four distinct, single-element, focused transducers were tested at fundamental frequencies of 500 kHz, 1 MHz, 2.5 MHz, and 5 MHz. In addition, the authors tested ultrasound transmission through the prosthesis using a linear diagnostic probe (center frequency 5.3 MHz) with a calibrated needle hydrophone in free water. Each transducer was assessed across a range of input voltages that encompassed their full minimum to maximum range without waveform distortion. They also tested the effect of the prosthesis on beam pressure and geometry. In the in vivo phase, the authors performed ultrasound imaging through the prosthesis implanted in a swine model.RESULTSAcoustic power attenuation through the prosthesis was considerably lower than that reported to occur through the native cranial bone. Increasing the frequency of the transducer augmented the degree of acoustic power loss. The degradation/distortion of the ultrasound beams passing through the prosthesis was minimal in all 3 spatial planes (XY, XZ, and YZ) that were examined. The images acquired in vivo demonstrated no spatial distortion from the prosthesis, with spatial relationships that were superimposable to those acquired through the dura.CONCLUSIONSThe results of the tests performed on the polyolefin-based cranial prosthesis indicated that this is a valid medium for delivering both focused and unfocused ultrasound and obtaining ultrasound images of the intracranial space. The prosthesis may serve for several diagnostic and therapeutic ultrasound-based applications, including bedside imaging of the brain and ultrasound-guided focused ultrasound cerebral procedures.

Sign in / Sign up

Export Citation Format

Share Document