scholarly journals Design of a Broadband Array Pattern of Underwater Cymbal Transducers

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6119
Author(s):  
Donghyun Kim ◽  
Hayeong Shim ◽  
Changmin Oh ◽  
Kyungseop Kim ◽  
Heeseon Seo ◽  
...  
Keyword(s):  
Energy Conversion Efficiency ◽  
Voltage Response ◽  
Single Element ◽  
Frequency Bandwidth ◽  
Fractional Bandwidth ◽  
Acoustic Characteristics ◽  
Structural Pattern ◽  
Array Pattern ◽  
Planar Array ◽  
The Difference

Cymbal transducers are frequently used as an array rather than a single element because of their high quality factor and low energy conversion efficiency. When used as an array, cymbal transducers are likely to have a big change in their frequency characteristics due to the interaction with neighboring elements. In this study, we designed an array pattern of cymbal transducers to achieve a wide frequency bandwidth using this property. First, cymbal transducers with specific center frequencies were designed. Next, a 2 × 2 planar array was constructed with the designed transducers, where dielectric polarity directions of the transducers were divided into two cases (i.e., same and different). For the array, the effect of the difference in the center frequencies and the spacing between the transducers on the acoustic characteristics of the entire array was analyzed. Based on the results, the structural pattern of the array was optimized to have the maximum fractional bandwidth while maintaining the transmitting voltage response over a given requirement. The design validity was verified by making cymbal array prototypes, followed by measuring their performances and comparing them with that of the design.

scholarly journals Design of Planar Array Transducers Based on Connected 1–3 Piezoelectric Composites

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1417
Author(s):  
Jiacheng Wang ◽  
Chao Zhong ◽  
Shaohua Hao ◽  
Ning Lv ◽  
Likun Wang
Keyword(s):  
Acoustic Radiation ◽  
Phase 1 ◽  
Beam Width ◽  
Voltage Response ◽  
Single Element ◽  
Two Phase ◽  
Piezoelectric Composites ◽  
Array Transducer ◽  
Three Phase ◽  
Planar Array

To improve the transmission performance and preparation of a transducer array, two planar array transducers based on connected 1–3 piezoelectric composites as a matrix were designed. Each transducer contained 25 array elements with a gap of 1 mm between them. The length, width and height of each array element were 1 mm, 26 mm and 5 mm, respectively. Two kinds of array transducers were tested through finite element simulation and experiments. The array transducer prototype was fabricated based on two kinds of composite materials, and the fabrication cycle was short. Our results show that the maximum transmission voltage response of the two-phase 1–3 full array driver is up to 179 dB at 200–400 kHz and the acoustic radiation intensity can be increased by up to 22% compared with the traditional splicing transducer array. It is suitable for short-range target positioning and measurement. Moreover, in the single element mode, the beam of the three-phase 1–3 transducer has no sidelobe and a single element −3 dB beam width of up to 91°. Furthermore, the beam width of the two-phase 1–3 type is 54°, and the acoustic radiation breadth is improved by 40.6%. The three-phase 1–3 type array transducer has the characteristics of concentrated acoustic transmission energy of the whole array, and its −3 dB beam width is 3.5°. The beam width decreased by 12.5%, indicating that the three-phase 1–3 type transducer is suitable for short-range target detection and perception. The two array transducers have their own advantages in transmitting the voltage response and beam width, which must be selected on the basis of the requirements of practical applications.

A Flextensional Transducer Prototype with PVDF Piezoelectric Film

2014 ◽  
Vol 670-671 ◽  
pp. 1153-1158
Author(s):  
Jing Jing Liu ◽  
Lei Qin ◽  
Li Kun Wang ◽  
Chao Zhong ◽  
Bin Zhang ◽  
...  
Keyword(s):  
Polyvinylidene Fluoride ◽  
Laser Scanning ◽  
Longitudinal Vibration ◽  
Voltage Response ◽  
Acoustic Measurement ◽  
Piezoelectric Film ◽  
Radial Vibration ◽  
Frequency Bandwidth ◽  
Metallic Shell ◽  
Flextensional Transducer

This paper presents a prototype of a new flextensional transducer with PVDF (Polyvinylidene Fluoride) piezoelectric film instead of metallic shell. Resonance frequency, bandwidth, transmitting voltage response, and horizontal directivity of the flextensional transducer with PVDF piezoelectric film were respectively measured by using laser-scanning vibrometer, and underwater acoustic measurement system. Experimental results showed that the new transducer features effectively conversion from longitudinal vibration of piezoelectric stack into radial vibration of PVDF piezoelectric film.

Freak Wave Generation in a Wave Basin With HOSM-WG Method

2015 ◽  
Author(s):  
Hidetaka Houtani ◽  
Takuji Waseda ◽  
Wataru Fujimoto ◽  
Keiji Kiyomatsu ◽  
Katsuji Tanizawa
Keyword(s):  
Control Method ◽  
Irregular Waves ◽  
Frequency Bandwidth ◽  
Freak Waves ◽  
Freak Wave ◽  
Wave Basin ◽  
Wave Trains ◽  
Directional Wave ◽  
Wave Maker ◽  
The Difference

A method to produce freak waves with arbitrary spectrum in a fully directional wave basin is presented here. This is an extension of Waseda, Houtani and Tanizawa at OMAE 2013[1], which used “HOSM-WG” based on the higher-order spectral method (HOSM). We used the following three methods to improve the HOSM-WG in [1]: “separation of free waves from bound waves,” “using Biesel’s transfer function in wavenumber space” and “using Schaffer’s 2nd-order wave maker control method.” Modulational wave trains, freak waves in unidirectional irregular waves and freak waves in short-crested irregular waves were generated in a wave basin. The experimental results using the improved HOSM-WG were compared to the HOSM simulation, and good agreements were found. The effectiveness of the improved HOSM-WG was ascertained. We showed that the difference between HOSM-WG and HOSM simulations became larger as wave steepness, frequency bandwidth of the spectrum or directional spreading became larger.

scholarly journals Linear and Planar Array Pattern Nulling via Compressed Sensing

2021 ◽  
Vol 3 ◽  
pp. 50-55
Author(s):  
Jafar Ramadhan Mohammed ◽  
Raad H. Thaher ◽  
Ahmed Jameel Abdulqader
Keyword(s):  
Compressed Sensing ◽  
Array Pattern ◽  
Planar Array

An Ultrasonic Based System to Measure Inter Spinous Process Distance in Humans: A Pilot Study

2005 ◽  
Author(s):  
Ariel Medina ◽  
Maruti R. Gudavalli ◽  
P. K. Raju ◽  
Gregory D. Cramer
Keyword(s):  
Standard Deviation ◽  
Human Subjects ◽  
Spinous Process ◽  
Lumbar Vertebrae ◽  
Single Element ◽  
Ultrasonic Signals ◽  
Two Dimensional Image ◽  
Spinous Processes ◽  
Human Volunteers ◽  
The Difference

The objective of this research project was to develop an ultrasonic based testing system and evaluate its application on human volunteers to locate and assess the distance between adjacent lumbar vertebrae. Tests were performed on ten volunteers aged between 19 and 29 years old during two sessions. The participants were asked to lie face down on a table with lower back section uncovered while the tests were executed. A computer controlled ultrasonic system was designed for this application. A single element 3.5 MHz immersion transducer held by a customized assembly was used to propagate and receive the ultrasonic signals. The transducer was moved along the assembly to fully scan at least two contiguous spinous processes. A Lab view based program was designed to generate a two-dimensional image (B-scan) that display the shape and position of the bone tips as well as the distance between them. The standard deviation obtained from the measurements of the distance between the tips of the spinous processes of human subjects, in a given session ranged from 0.1–0.48mm. The difference between two sessions had a mean of 0.85–0.95 mm and a standard deviation of 0.87–1.03mm with reliability coefficients greater than 0.95. The study demonstrated the viability of utilizing ultrasound to precisely measure the distance between spinous processes of adjacent lumbar vertebrae.

Simulation Study for the Series Connected Bundles of Microtubular SOFCs

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
Yoshihiro Funahashi ◽  
Toru Shimamori ◽  
Toshio Suzuki ◽  
Yoshinobu Fujishiro ◽  
Masanobu Awano ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Solid Oxide Fuel Cells ◽  
Simulation Study ◽  
Energy Conversion Efficiency ◽  
Total Output ◽  
Fabrication Technology ◽  
Power Generators ◽  
Current Collection ◽  
The Difference ◽  
Bundle Structure

Solid oxide fuel cells (SOFCs) have the highest energy conversion efficiency among various power generators and expected to be earlier commercialization. Our study aims to develop fabrication techniques of microtubular SOFC bundles and establish realistic bundle structure for kilowatt class module. So far, we have succeeded to establish fabrication technology of the microtubular SOFC bundles using porous supporting matrices. In this study, the simulation study of the microtubular SOFC bundle was carried out to understand Joule heat and temperature distribution in the microtubular SOFC bundle during operation. The results indicated that the method of current collection had to be carefully considered, since the total output power loss of the bundle was estimated to be 27.8%. The temperature distribution of the bundle using porous MgO matrices turned out to be moderate compared with that in the previous bundle using porous (La,Sr)(Co,Fe)O3 matrices due to the difference in the thermal conductivity of each matrix constitute.

scholarly journals Effects of WO 3 electrode microstructure on NO 2 -sensing properties for a potentiometric sensor

2019 ◽  
Vol 6 (7) ◽  
pp. 190526
Author(s):  
Bin Yang ◽  
Jianzhong Xiao ◽  
Chao Wang
Keyword(s):  
Gas Phase ◽  
Electrochemical Impedance ◽  
Electrochemical Reaction ◽  
Voltage Response ◽  
Electrode Thickness ◽  
Adsorption Sites ◽  
Three Phase ◽  
The Difference ◽  
Sensing Performance ◽  
Scanning Electron

Planar potentiometric NO 2 sensors based on 8YSZ (8 mol% Y 2 O 3 -doped ZrO 2 ) were prepared with WO 3 sensing electrode material. The various electrode microstructures prepared by different sintering temperatures were characterized by field emission scanning electron microscopy (SEM), and the microstructure influences on the sensors' performances were investigated. The sensor sintered at 800°C, with the most reaction sites, moderate adsorption sites and appropriate electrode thickness, exhibits the highest NO 2 voltage response. While the sensor sintered at 750°C exhibits the lowest NO 2 sensitivity because of the strongest gas-phase catalytic consumption in the WO 3 sensing electrode. Based on the results of SEM characterization and electrochemical impedance spectroscopy tests, the difference in NO 2 -sensing performance was attributed to different amounts of electrochemical reaction sites at three-phase boundary, adsorption sites and different degrees of gas-phase catalysis.

Comparison of seismic upscaling methods: From sonic to seismic

Geophysics ◽  
2009 ◽  
Vol 74 (2) ◽  
pp. WA3-WA14 ◽  
Author(s):  
Dileep K. Tiwary ◽  
Irina O. Bayuk ◽  
Alexander A. Vikhorev ◽  
Evgeni M. Chesnokov
Keyword(s):  
Elastic Wave ◽  
Pair Correlation ◽  
P Wave ◽  
Frequency Bandwidth ◽  
Frequency Range ◽  
S Wave ◽  
Wave Velocities ◽  
Backus Averaging ◽  
The Difference ◽  
Gas Bearing

The term “upscaling” used here means a prediction of elastic-wave velocities at lower frequencies from the velocities at higher frequencies. Three different methods of upscaling are considered, including the simple averaging, Backus averaging, and pair correlation function methods. These methods are applied to upscale the elastic-wave velocities measured at sonic frequencies ([Formula: see text], logging data) available for a well penetrating layers of gas-bearing shales and carbonates. As a result, a velocity distribution over depth for [Formula: see text] and [Formula: see text] is found in the frequency range of [Formula: see text]. The difference in the results obtained for a particular depth by the three theoretical methods in the surface seismic frequency bandwidth [Formula: see text] is [Formula: see text] for P-wave and [Formula: see text] for S-wave velocity. This difference is attributed to different theoretical backgrounds underlying these methods.

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