scholarly journals Preliminary Investigation of Magnetic Resonance Imaging Guided Beamforming in Flexible Type Ultrasonic Array Transducers

2021 ◽  
Vol 9 ◽  
Author(s):  
Koki Hasegawa ◽  
Kengo Namekawa ◽  
Shinji Takayanagi ◽  
Iwaki Akiyama
Keyword(s):  
Focal Point ◽  
Piezoelectric Materials ◽  
Preliminary Investigation ◽  
Beam Width ◽  
Lateral Direction ◽  
Practical Applications ◽  
Field Environment ◽  
Array Transducer ◽  
Ultrasonic Array ◽  
Set Up

A flexible-shaped ultrasonic array probe that can be used in a high magnetic field environment in an MRI gantry has been developed. Given that this probe can be fixed according to the shape of the skull’s surface, it is particularly applicable for imaging in the brain. To perform ultrasonic beamforming using a bent probe, it is necessary to measure the bent shape. Therefore, in this research, the curvature of the probe was estimated using MRI. A phantom with ellipse surface close to the shape of a skull was created using a 3D printer. The probe was arranged along the phantom surface to perform MRI and ultrasonic beamforming. The ultrasonic array transducer had 192 elements made from 1-3 composite piezoelectric materials with an element spacing of 0.3 mm. Eight MR position markers were attached to the probe in parallel in two rows of four each, with the array transducer in between. The delay time of each element in dynamic focusing for reception was calculated from its position estimated by the curvature of the probe. To evaluate the feasibility of this method, a B-mode image of 0.98 mm-diameter-thread targets placed in water was generated. The beam width at half maximum of the echo peak in the lateral direction from the thread target set up near the transmission focal point was calculated based on the B-mode image. It was found that the beam width of 1.32 mm in the proposed method, which was close to the thread diameter, whereas that was 4.38 mm in the conventional method that did not consider the bending of the probe. Consequently, the proposed beamforming technique is feasible for ultrasonic imaging through an arbitrary curved surface. Practical applications with a head phantom mimicking skull and cerebral tissue are expected.

Preliminary Investigation on the Flexural Behaviour of Steel Fibre Reinforced Self-Compacting Concrete Ribbed Slab

2018 ◽  
Vol 15 (1) ◽  
pp. 31
Author(s):  
Nur Aiman Suparlan ◽  
Muhammad Azrul Ku Ayob ◽  
Hazrina Ahmad ◽  
Siti Hawa Hamzah ◽  
Mohd Hisbany Mohd Hashim
Keyword(s):  
Ultimate Load ◽  
Steel Fibre ◽  
Preliminary Investigation ◽  
Bending Test ◽  
Flexural Behaviour ◽  
Self Compacting Concrete ◽  
Two Samples ◽  
Simple Support ◽  
Set Up ◽  
Ultimate Load Carrying Capacity

A ribbed slab structure has the advantage in the reduction of concrete volume in between the ribs resulting in a lower structural self-weight. In order to overcome the drawbacks in the construction process, the application of steel fibre self-compacting concrete (SCFRC) is seen as an alternative material to be used in the slab. This preliminary investigation was carried out to investigate the flexural behaviour of steel fibre self-compacting concrete (SCFRC) as the main material in ribbed slab omitting the conventional reinforcements. Two samples of ribbed slab were prepared for this preliminary study; 2-ribbed and 3-ribbed in 1 m width to identify the effect of the geometry to the slab’s flexural behaviour. The dimension of both samples is 2.5 m x 1 m with 150 mm thickness. The compressive strength of the mix is 48.6 MPa based on the cubes tested at 28 days. Load was applied to failure by using the four point bending test set-up with simple support condition. The result of the experiment recorded ultimate load carrying capacity at 30.68 kN for the 2-ribbed slab and 25.52 kN for 3-ribbed slab. From the results, the ultimate load of the 2-ribbed sample exceeds 3-ribbed by approximately 20%. This proved that even with lower concrete volume, the sample can still withstand an almost similar ultimate load. Cracks was also observed and recorded with the maximum crack width of 2 mm. It can be concluded that the steel fibres do have the potential to withstand flexural loadings. Steel fibre reduces macro-crack forming into micro-cracks and improves concrete ductility, as well as improvement in deflection. This shows that steel fibre reinforced self-compacting concrete is practical as it offers good concrete properties as well as it can be mixed, placed easier without compaction. 

scholarly journals Towards Zero Emissions Noosa

2019 ◽  
Vol 11 (17) ◽  
pp. 4679
Author(s):  
Carina Anderson ◽  
Robert Passey ◽  
Jeremy De Valck ◽  
Rakibuzzaman Shah
Keyword(s):  
Community Engagement ◽  
Focal Point ◽  
Contextual Information ◽  
Renewable Electricity ◽  
Community Group ◽  
Course Of Action ◽  
Engagement Process ◽  
Set Up ◽  
External Consultant

This paper reports on a case study of the community group Zero Emissions Noosa, whose goal is for 100% renewable electricity in the Noosa Shire (Queensland, Australia) by 2026. Described within this paper are the processes used by Zero Emissions Noosa to set up their zero emissions plan, involving community engagement and the use of an external consultant. The external consultant was employed to produce a detailed report outlining how to successfully achieve zero emissions from electricity in the Noosa Shire by 2026. This paper explains how and why the community engagement process used to produce the report was just as important as the outcomes of the report itself. Modeling was undertaken, and both detailed and contextual information was provided. Inclusion of the community in developing the scenario parameters for the modeling had a number of benefits including establishing the context within which their actions would occur and focusing their efforts on options that were technically feasible, financially viable and within their capabilities to implement. This provided a focal point for the community in calling meetings and contacting stakeholders. Rather than prescribing a particular course of action, it also resulted in a toolbox of options, a range of possible solutions that is flexible enough to fit into whatever actions are preferred by the community. The approach and outcomes discussed in this paper should, therefore, be useful to other communities with similar carbon emission reduction goals.

scholarly journals Weavers & Warriors? Gender and Online Identity in 1997 and 2007 V1.0

2008 ◽  
Vol 2 (2) ◽  
Author(s):  
Deirdre Ruane
Keyword(s):  
Preliminary Investigation ◽  
The Body ◽  
Internet Technology ◽  
Online Identity ◽  
Men And Women ◽  
Online Interactions ◽  
And Performance ◽  
And Gender ◽  
Set Up ◽  
Active Exploration

In 1997 the Internet was seen by many as a tool for radical reinterpretation of physicality and gender. Cybertheorists predicted we would leave our bodies behind and interact online as disembodied minds, and that the technology would reshape the way we saw ourselves. However, physicality has proved to be an inextricable part of all our interactions. Changing Internet technology has allowed Net users to find a myriad ways to perform and express their gender online. In this paper I consider attitudes to gender on the Net in 1997, when the main concerns were the imbalance between men and women online and whether it was possible or desirable to bring the body into online interactions. In much of the discourse surrounding gender online, a simple binary was assumed to exist. I go on to consider the extent to which those attitudes have changed today. Through my own experience of setting up a women’s community on Livejournal, and my observations of a men’s community set up in response, I conclude that though traditional attitudes to gender have largely translated to the Net and the binary is still the default view, some shifts have occurred. For example, between 1997 and today there seems to have been a fundamental change in perceptions of women’s attitudes to adversarial debate, and an increase in awareness of genders beyond the binary. In addition, experience and preliminary investigation lead me toward a hypothesis that today’s female-identified Net users are engaged in more conscious and active exploration and performance of their gender online than male-identified users are.

Enhanced fatigue resistance and lattice dynamics induced by the strong local strain in Fe-doped KTa1-xNbxO3 single crystal

2021 ◽  
Author(s):  
Xiaolin Huang ◽  
Peng Tan ◽  
Yu Wang ◽  
Yao Zhang ◽  
Xiangda Meng ◽  
...  
Keyword(s):  
Single Crystal ◽  
Fatigue Resistance ◽  
Lattice Dynamics ◽  
Piezoelectric Materials ◽  
Local Strain ◽  
Lead Free ◽  
Fatigue Properties ◽  
Practical Applications ◽  
Local Structures ◽  
The Impact

Improvement of durability is greatly important for the practical applications of lead-free-doped piezoelectric materials. However, the promotional mechanism of anti-fatigue properties and the impact on local structures from ion dopants...

scholarly journals Micromachining of High Quality PMN–31%PT Single Crystals for High-Frequency (>20 MHz) Ultrasonic Array Transducer Applications

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 512 ◽  
Author(s):  
Zhihong Lei ◽  
Yan Chen ◽  
Guisheng Xu ◽  
Jinfeng Liu ◽  
Maodan Yuan ◽  
...  
Keyword(s):  
High Frequency ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Properties ◽  
Urgent Problem ◽  
High Quality ◽  
Laser Parameters ◽  
Array Transducer ◽  
Micro Cracks ◽  
Ultrasonic Array ◽  
Piezoelectric Performance

A decrease of piezoelectric properties in the fabrication of ultra-small Pb(Mg1/3Nb2/3)–x%PbTiO3 (PMN–x%PT) for high-frequency (>20 MHz) ultrasonic array transducers remains an urgent problem. Here, PMN–31%PT with micron-sized kerfs and high piezoelectric performance was micromachined using a 355 nm laser. We studied the kerf profile as a function of laser parameters, revealing that micron-sized kerfs with designated profiles and fewer micro-cracks can be obtained by optimizing the laser parameters. The domain morphology of micromachined PMN–31%PT was thoroughly analyzed to validate the superior piezoelectric performance maintained near the kerfs. A high piezoresponse of the samples after micromachining was also successfully demonstrated by determining the effective piezoelectric coefficient (d33*~1200 pm/V). Our results are promising for fabricating superior PMN–31%PT and other piezoelectric high-frequency (>20 MHz) ultrasonic array transducers.

Teaching Criminology and Police Science for Postgraduate Students at the Ruhr- University Bochum, Germany

2010 ◽  
pp. 177-193
Author(s):  
Diana Ziegleder ◽  
Felix Feldmann-Hahn
Keyword(s):  
Focal Point ◽  
Full Time ◽  
Master's Program ◽  
Postgraduate Students ◽  
New Concepts ◽  
History Of ◽  
E Learning ◽  
Set Up ◽  
Insight Into

This case study looks at the postgraduate program in Criminology and Police Science at the Ruhr- University Bochum, Germany. This practice oriented course of study is designed as a distance learning course (blended learning) and therefore focuses on techniques of e-learning. The case study describes the history of origins and examines the educational situation before this master’s program was established and how an idea became reality. It is one of the very few possibilities in Germany to receive a deeper insight into criminology and police science. Despite the fact, that the students are all professionals and thus working mostly full time, the technical premises make a discourse possible as in on-campus programs. These innovative forms of learning are the focal point of the following case study. It is our aim to provide insight into how a master’s program could be set up and to promote new concepts of e-learning in the field of criminology.

scholarly journals Analysis of Linear Non-Destructive Testing and Evaluation Methods for Thin-Walled Structure Inspection Using Ultrasonic Array

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 146
Author(s):  
Yang Li ◽  
Zhenggan Zhou ◽  
Jun Wang
Keyword(s):  
Signal To Noise Ratio ◽  
Near Field ◽  
Central Frequency ◽  
Destructive Testing ◽  
Array Transducer ◽  
Imaging Results ◽  
Ultrasonic Array ◽  
Thin Walled ◽  
Aluminum Plates ◽  
Non Destructive

The ultrasonic array used for thin-walled structure non-destructive inspection usually has a high central frequency so that the thickness-to-acoustic wavelength ratio is greater than 10. When the ratio is much smaller than 10, the reliability of the conventional ultrasonic array method will dramatically decrease due to the influence of the acoustic near-field. This situation is unavoidable since the available central frequency of the array transducer cannot be an arbitrarily large value. To optimize the inspection performance in this case, the testing of an ultrasonic array and the evaluation of a structure whose thickness is smaller than five-times the longitudinal wavelength are analyzed in this paper. Linear ultrasonic array methods using different combinations of wave patterns, reflection times, and coupling conditions are uniformly expressed as full matrix algorithms. Simulated and experimental full matrices of 6 mm-thick aluminum plates using a 5-MHz array transducer are captured to analyze their imaging performances and sizing abilities with respect to various defects. Analyses show that the inspection results of the wedge coupling method have a much higher signal-to-noise ratio (SNR) than the results of conventional direct contact methods. Circular defects and rectangular defects can be distinguished by comparing the imaging results of different modes. For the simulated circular defect, the diameter can be measured according to the maximum image amplitude of the defect. To simulate a rectangular defect located in the lower half of the region, the nominal length can be measured using a linear function whose input is a −6 dB drop in length of the SS-S mode image. For a real sample, the material anisotropy and complex self-reflections will decrease the SNR by about 10 dB.

scholarly journals A Simplified Finite Element Approach for Modeling of Multilayer Plates

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Taiyou Liu ◽  
Xinbo Ma ◽  
Pak Kin Wong ◽  
Jing Zhao ◽  
Zhengchao Xie ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Reference Value ◽  
Fe Model ◽  
Practical Applications ◽  
Aerospace Applications ◽  
Equivalent Bending Stiffness ◽  
Element Approach ◽  
Set Up ◽  
Transverse Response

The multilayer plate has a great potential for automotive and aerospace applications. However, the complexity in structure and calculation of the response impede the practical applications of multilayer plates. To solve this problem, this work proposes a new plate finite element and a simplified finite element (FE) model for multilayer plates. The proposed new plate finite element consists of the shear and extension strains in all layers. The multilayer structure with the proposed new plate finite element is regarded as a reference to calculate the reference value of the transverse response. The simplified FE model of multilayer plates is proposed based on the equivalent bending stiffness by curve fitting of the reference value of the transverse response. Numerical study shows that this approach can be used to set up the simplified FE model of multilayer plates.

Rapid Non-Destructive Testing of Ceramic Multilayer Capacitors by a Resonance Method

1988 ◽  
Vol 142 ◽  
Author(s):  
O. Boser ◽  
P. Kellawon ◽  
R. Geyer
Keyword(s):  
Acoustic Waves ◽  
High Speed ◽  
Piezoelectric Materials ◽  
Resonance Method ◽  
Test Method ◽  
Test Set ◽  
Speed Test ◽  
Multilayer Capacitors ◽  
Set Up ◽  
Non Destructive

AbstractA rapid non-destructive test method for ceramic multilayer capacitors made from piezoelectric materials such as barium titanate or lead containing materials is described and evaluated. The test method is based on the internal excitation of standing acoustic waves in the capacitors. The standing waves are severely dampened by defects such as delaminations and pores. An undampened resonance is a good indication of a defect free ceramic multilayer capacitor. This finding was used in a nondestructive test set-up to evaluate about 1,000 capacitors. The test set-up has the potential to test over 100,000 capacitors an hour. Through metallographic (cross section) examination a sorting accuracy of 2% false accepts and 8% false rejects was determined for the high speed test set-up.

The effect of plasma channel on the self-distortion of laser pulse propagating through the collisionless plasma channel

2014 ◽  
Vol 23 (03) ◽  
pp. 1450027
Author(s):  
Navpreet Singh ◽  
Arvinder Singh
Keyword(s):  
Laser Pulse ◽  
Differential Equations ◽  
Density Profile ◽  
Plasma Channel ◽  
Collisionless Plasma ◽  
Beam Width ◽  
Low Intensity ◽  
Pulse Distortion ◽  
Set Up ◽  
Preformed Plasma

This paper presents an investigation of the laser pulse distortion/breakup and the effect of the plasma channel on the laser propagation through the collisionless plasma. Moment theory has been used to derive differential equations of the beam width parameter of the laser propagating through uniform homogenous plasma and preformed plasma channel having parabolic density profile. Differential equations have been set up and solved numerically by using Runge Kutta method. From analysis, it is observed that the low intensity front and rear parts of the laser pulse get defocused/diffracted while the high intensity central portion of the laser pulse gets self-guided during the propagation through uniform homogenous plasma. As a result of this, laser pulse gets distorted. This distortion of the laser pulse has not been observed when the laser beam is propagated through the plasma channel having parabolic density profile. The laser pulse is guided as a whole, even the low intensity front and rear parts of the laser pulse are also guided. Therefore, it is predicted that plasma channel plays a significant role to prevent the distortion/beam breakup of the laser.

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