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Modelagem de ensaios não destrutivos por ultra-som utilizando o método dos elementos finitos. ; Modeling of ultrasonic non destructive evaluation using FEM.

San Miguel Medina, Jimmy Ernesto
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/12/2005 PT
Relevância na Pesquisa
57.05%
Os modelos existentes de propagação de ondas de ultra-som em meios líquidos e sólidos consideram a geração e recepção das ondas produzidas por transdutores simulados segundo o modelo do pistão plano ou com excitações cuja amplitude varia radialmente no pistão. Esses modelos são simplificados e não explicam completamente o comportamento real de transdutores de ultra-som interagindo com líquidos e sólidos. As verificações experimentais de propagação da onda de ultra-som em meios líquidos mostram que a onda de borda é diferente da onda plana. Observa-se também a existência de outras ondas não previstas nos modelos anteriores. Essas ondas são conhecidas como ondas head. A utilização do método dos elementos finitos (MEF) para a modelagem de propagação de ondas de ultra-som, incluindo o transdutor piezelétrico, permite a obtenção de resultados realísticos, conseguindo assim descrever com maior precisão o comportamento do transdutor e das ondas de ultra-som se propagando em diferentes meios e interagindo com defeitos que se comportam como refletores. Apesar disso, os resultados desses modelos dependem das características precisas dos materiais que compõem o transdutor. O transdutor de ultra-som é composto por uma cerâmica piezelétrica...

Hidrofone ultrassônico com piezoeletreto como elemento transdutor; Ultrasonic hydrophone with piezoelectret as transducer element

Medeiros, Leandro José de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/03/2014 PT
Relevância na Pesquisa
46.72%
Desde o ano 2000, o Grupo de Alta Tensão e Materiais (GATM) tem contribuído com suas pesquisas no desenvolvimento de processos para produção de novos transdutores piezoelétricos de materiais poliméricos, baseados na tecnologia dos piezoeletretos. Essa intensa investigação se justifica pelas excelentes propriedades piezoelétricas desses dispositivos, com atividade na ordem de centenas e até milhares de pC/N, ultrapassando o desempenho de algumas tradicionais cerâmicas. Destacam-se também nestes sensores, sua estrutura flexível e robusta, sua resposta na faixa de frequências ultrassônicas e seu baixo custo. Características estas que os tornam muito competitivos com os transdutores convencionais, cerâmicos e poliméricos, a exemplo do PZT e PVDF, respectivamente. Neste contexto, desenvolveu-se em 2009 no GATM um novo arranjo polimérico de múltiplos canais, em que filmes de teflon FEP foram termicamente moldados e depois expostos a um intenso campo elétrico (na ordem de kV), criando sensores com elevado coeficiente piezoelétrico. Esse novo dispositivo, batizado de Piezoeletreto de Canais Tubulares (PCT) foi construído por meio de um processo de fabricação organizado e controlado, diferentemente dos piezoeletretos vistos até então. No presente trabalho construiu-se um protótipo de hidrofone com elemento ativo dado por um filme de PCT...

Desenvolvimento de um transdutor ultrassônico de potência aplicado em perfuração de rochas e usinagem de metais.; Development of a power ultrasonic transducer applied in drilling machining of metals and rock perforation.

Tayra, Victor Thomas
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/06/2014 PT
Relevância na Pesquisa
46.79%
A sobreposição de frequências ultrassônicas a uma ferramenta em operações de perfuração, utilizando transdutores piezelétricos, resulta em melhorias na usinagem de metais, garantindo melhor acabamento (ausência de rebarba), redução do tamanho do cavaco e menor desgaste ferramental. A utilização desse tipo de técnica na perfuração de rochas reduz a carga axial e aumenta a velocidade do processo, possibilitando maior profundidade de perfuração, podendo vir a ser muito útil em pesquisas aplicadas à perfuração de reservas petrolíferas e exploração mineral. Este trabalho teve como objetivo simular e aplicar um transdutor piezelétrico ultrassônico de potência para perfuração de rochas e metais. Para as simulações numéricas duas técnicas foram utilizadas: o método dos elementos finitos (MEF) e o método das matrizes em cadeia (MMC). O MEF permitiu análises harmônicas e modais de forma rápida e precisa enquanto o MMC resultou em expressão analítica, possibilitando melhor compreensão dos parâmetros físicos e geométricos envolvidos na performance do transdutor. Ambos os métodos nortearam o projeto do protótipo a ser usado em ensaios de perfuração. Para a construção do protótipo, foi projetado um mandril para a fixação da broca...

Micropilares de PVDF, microrreatores de PDMS e aceleração de reações sonoquímicas com o transdutor ultrassônico do polímero fluoreto de polivinilideno; PVDF micropillars, PDMS microreactors and acceleration of sonochemical reactions with the ultrasonic transducer of the polymer polyvinylidene fluoride

Reinaldo Alberto Ricchi Junior
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/02/2013 PT
Relevância na Pesquisa
46.66%
A versatilidade do polifluoreto de vinilideno (PVDF) abriu um grande número de possibilidades de pesquisa para este trabalho. Após uma completa revisão bibliográfica sobre as aplicações deste material, o transdutor ultrassônico de PVDF, acoplado a um reator e a um microreator do elastômero polidimetilsiloxano (PDMS), foi o sistema escolhido para esta tese. Tal sistema acelerou reações de Morita-Baylis-Hillman (MBH). O primeiro teste foi realizado em um reator "macroscópico" de PDMS para analisar o comportamento da reação MBH com este material. Em seguida, após o aprofundamento dos estudos, foi realizada uma reação MBH no interior do microreator, também de PDMS, e os resultados mostraram que o fenômeno de cavitação é significativamente maior neste caso, abrindo perspectivas para trabalhos futuros. Análises de espectroscopia de ressonância magnética nuclear (RMN) e de cromatografia gasosa (CG) comprovaram a eficácia do transdutor ultrassônico. Também foram fabricadas microestruturas de PVDF pela técnica de Litografia Macia por um novo processo, abrindo novas perspectivas de pesquisa.; The versatility of polyvinylidene fluoride (PVDF) has opened a lot of possibilities for this research work. After a literature review about the applications of this material...

Acoustic beam modeling of ultrasonic transducers and arrays using the impulse response and the discrete representation methods

Franco,Ediguer E.; Andrade,Marco A. B.; Adamowski,Julio C.; Buiochi,Flávio
Fonte: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM Publicador: Associação Brasileira de Engenharia e Ciências Mecânicas - ABCM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
46.56%
The impulse response of the velocity potential and the discrete representation methods were used in order to model the acoustic field radiated by ultrasonic transducers and arrays. The first method deals with the calculation of the exact impulse response, in which solutions are possible only for simple geometries, such as the circular piston. The second method is an approximated solution based on the discretization of the acoustic aperture in small elementary areas, each of them radiating a spherical wave. By using circular transducers, which can be considered circular pistons, many simulations comparing the methods were carried out. The relation between the computational cost and the precision was analyzed, thus establishing the time and space discretization levels. The simulations were made using the Matlab software and the results were compared to experimental measurements showing good agreement. The experimental results were obtained using a scanning system. The acoustic field radiated from a 1 MHz circular transducer was measured as well as a 3.5 MHz array of 16 elements both immersed in water. The acoustic field radiated by the array was simulated and measured with focalization on a radius of 30 mm with deflections of 0º and 20º.

Integration of Trench-Isolated Through-Wafer Interconnects with 2D Capacitive Micromachined Ultrasonic Transducer Arrays

Zhuang, Xuefeng; Ergun, Arif S.; Huang, Yongli; Wygant, Ira O.; Oralkan, Omer; Khuri-Yakub, Butrus T.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 20/07/2007 EN
Relevância na Pesquisa
46.55%
This paper presents a method to provide electrical connection to a 2D capacitive micromachined ultrasonic transducer (CMUT) array. The interconnects are processed after the CMUTs are fabricated on the front side of a silicon wafer. Connections to array elements are made from the back side of the substrate via highly conductive silicon pillars that result from a deep reactive ion etching (DRIE) process. Flip-chip bonding is used to integrate the CMUT array with an integrated circuit (IC) that comprises the front-end circuits for the transducer and provides mechanical support for the trench-isolated array elements. Design, fabrication process and characterization results are presented. The advantages when compared to other through-wafer interconnect techniques are discussed.

Lead-free KNLNT Piezoelectric Ceramics for High-frequency Ultrasonic Transducer Application

Wu, D. W.; Chen, R. M.; Zhou, Q. F.; Shung, K. K.; Lin, D.M.; Chan, H. L. W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
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This paper presents the latest development of a lead-free piezoelectric ceramic and its application to transducers suitable for high-frequency ultrasonic imaging. A lead-free piezoelectric ceramic with formula of (K0.5Na0.5)0.97Li0.03(Nb0.9 Ta0.1)O3 (abbreviated as KNLNT-0.03/0.10) was fabricated and characterized. The material was found to have a clamped dielectric constant ε33S = ε0 = 890, piezoelectric coefficient d33 = 245 pC/N, electromechanical coupling factor kt = 0.42 and Curie temperature Tc > 300 °C. High-frequency (40 MHz) ultrasound transducers were successfully fabricated with the lead-free material. A representative lead-free transducer had a bandwidth of 45%, two-way insertion loss of −18 dB. This performance is comparable to reported performances of popular lead-based transducers. The comparison results suggest that the lead-free piezoelectric material may serve as an alternative to lead-based piezoelectric materials for high-frequency ultrasonic transducer applications.

Microscale 1–3-Type (Na,K)NbO3-Based Pb-Free Piezocomposites for High-Frequency Ultrasonic Transducer Applications

Shen, Zong-Yang; Li, Jing-Feng; Chen, Ruimin; Zhou, Qifa; Shung, K. Kirk
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/2011 EN
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46.66%
Fine-grained Pb-free (Na0.535K0.485)0.95Li0.05(Nb0.8Ta0.2)O3 (NKLNT) piezoceramics prepared by spark plasma sintering (SPS) technique was used to fabricate NKLNT/epoxy 1–3 composites with a modified dice–fill method. Because of its good machinability, SPSed NKLNT ceramic rods could be miniaturized to a lateral width of 50 µm. After lapping down to 56 µm in thickness, the composite was used to fabricate an ultrasonic transducer as the active piezoelectric element. This composite transducer showed a bandwidth at −6 dB nearly 90%at a center frequency of 29 MHz, demonstrating that this Pb-free composite thick film is very promising for the fabrication of high-frequency ultrasonic transducers in medical imaging applications.

Design of a Smart Ultrasonic Transducer for Interconnecting Machine Applications

Yan, Tian-Hong; Wang, Wei; Chen, Xue-Dong; Li, Qing; Xu, Chang
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 24/06/2009 EN
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46.86%
A high-frequency ultrasonic transducer for copper or gold wire bonding has been designed, analyzed, prototyped and tested. Modeling techniques were used in the design phase and a practical design procedure was established and used. The transducer was decomposed into its elementary components. For each component, an initial design was obtained with simulations using a finite elements model (FEM). Simulated ultrasonic modules were built and characterized experimentally through the Laser Doppler Vibrometer (LDV) and electrical resonance spectra. Compared with experimental data, the FEM could be iteratively adjusted and updated. Having achieved a remarkably highly-predictive FEM of the whole transducer, the design parameters could be tuned for the desired applications, then the transducer is fixed on the wire bonder with a complete holder clamping was calculated by the FEM. The approach to mount ultrasonic transducers on wire bonding machines also is of major importance for wire bonding in modern electronic packaging. The presented method can lead to obtaining a nearly complete decoupling clamper design of the transducer to the wire bonder.

In vivo photoacoustic microscopy with 7.6-µm axial resolution using a commercial 125-MHz ultrasonic transducer

Zhang, Chi; Maslov, Konstantin; Yao, Junjie; Wang, Lihong V.
Fonte: Society of Photo-Optical Instrumentation Engineers Publicador: Society of Photo-Optical Instrumentation Engineers
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.66%
Photoacoustic microscopy has achieved submicron lateral resolution, but its axial resolution is much lower. Here an axial resolution of 7.6 μm, the highest axial resolution validated by experimental data, has been achieved by using a commercial 125 MHz ultrasonic transducer for signal detection followed by the Wiener deconvolution for signal processing. Limited by the working distance, the high-frequency ultrasonic transducer can penetrate 1.2 mm into biological tissue from the ultrasound detection side. At this depth, the signal-to-noise ratio decreases by 11 dB, and the axial resolution degrades by 36%. The new system was demonstrated in imaging melanoma cells ex vivo and mouse ears in vivo.

Applications of Flexible Ultrasonic Transducer Array for Defect Detection at 150 °C

Shih, Jeanne-Louise; Wu, Kuo-Ting; Jen, Cheng-Kuei; Chiu, Chun-Hsiung; Tzeng, Jing-Chi; Liaw, Jiunn-Woei
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 15/01/2013 EN
Relevância na Pesquisa
46.62%
In this study, the feasibility of using a one dimensional 16-element flexible ultrasonic transducer (FUT) array for nondestructive testing at 150 °C is demonstrated. The FUT arrays were made by a sol-gel sprayed piezoelectric film technology; a PZT composite film was sprayed on a titanium foil of 75 μm thickness. Since the FUT array is flexible, it was attached to a steel pipe with an outer diameter of 89 mm and a wall thickness of 6.5 mm at 150 °C. Using the ultrasonic pulse-echo mode, pipe thickness measurements could be performed. Moreover, using the ultrasonic pulse-echo and pitch-catch modes of each element of FUT array, the defect detection was performed on an Al alloy block of 30 mm thickness with a side-drilled hole (SDH) of ϕ3 mm at 150 °C. In addition, a post-processing algorithm based on the total focusing method was used to process the full matrix of these A-scan signals of each single transmitter and multi-receivers, and then the phase-array image was obtained to indicate this defect- SDH. Both results show the capability of FUT array being operated at 150 °C for the corrosion and defect detections.

Crack Orientation and Depth Estimation in a Low-Pressure Turbine Disc Using a Phased Array Ultrasonic Transducer and an Artificial Neural Network

Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 13/09/2013 EN
Relevância na Pesquisa
46.66%
Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks.

A Spherically-Shaped PZT Thin Film Ultrasonic Transducer with an Acoustic Impedance Gradient Matching Layer Based on a Micromachined Periodically Structured Flexible Substrate

Feng, Guo-Hua; Liu, Wei-Fan
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 09/10/2013 EN
Relevância na Pesquisa
46.66%
This paper presents the microfabrication of an acoustic impedance gradient matching layer on a spherically-shaped piezoelectric ultrasonic transducer. The acoustic matching layer can be designed to achieve higher acoustic energy transmission and operating bandwidth. Also included in this paper are a theoretical analysis of the device design and a micromachining technique to produce the novel transducer. Based on a design of a lead titanium zirconium (PZT) micropillar array, the constructed gradient acoustic matching layer has much better acoustic transmission efficiency within a 20–50 MHz operation range compared to a matching layer with a conventional quarter-wavelength thickness Parylene deposition. To construct the transducer, periodic microcavities are built on a flexible copper sheet, and then the sheet forms a designed curvature with a ball shaping. After PZT slurry deposition, the constructed PZT micropillar array is released onto a curved thin PZT layer. Following Parylene conformal coating on the processed PZT micropillars, the PZT micropillars and the surrounding Parylene comprise a matching layer with gradient acoustic impedance. By using the proposed technique, the fabricated transducer achieves a center frequency of 26 MHz and a −6 dB bandwidth of approximately 65%.

Defect Inspection of Flip Chip Solder Bumps Using an Ultrasonic Transducer

Su, Lei; Shi, Tielin; Xu, Zhensong; Lu, Xiangning; Liao, Guanglan
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 27/11/2013 EN
Relevância na Pesquisa
46.72%
Surface mount technology has spurred a rapid decrease in the size of electronic packages, where solder bump inspection of surface mount packages is crucial in the electronics manufacturing industry. In this study we demonstrate the feasibility of using a 230 MHz ultrasonic transducer for nondestructive flip chip testing. The reflected time domain signal was captured when the transducer scanning the flip chip, and the image of the flip chip was generated by scanning acoustic microscopy. Normalized cross-correlation was used to locate the center of solder bumps for segmenting the flip chip image. Then five features were extracted from the signals and images. The support vector machine was adopted to process the five features for classification and recognition. The results show the feasibility of this approach with high recognition rate, proving that defect inspection of flip chip solder bumps using the ultrasonic transducer has high potential in microelectronics packaging.

Systematic study of high-frequency ultrasonic transducer design for laser-scanning photoacoustic ophthalmoscopy

Ma, Teng; Zhang, Xiangyang; Chiu, Chi Tat; Chen, Ruimin; Kirk Shung, K.; Zhou, Qifa; Jiao, Shuliang
Fonte: Society of Photo-Optical Instrumentation Engineers Publicador: Society of Photo-Optical Instrumentation Engineers
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.79%
Photoacoustic ophthalmoscopy (PAOM) is a high-resolution in vivo imaging modality that is capable of providing specific optical absorption information for the retina. A high-frequency ultrasonic transducer is one of the key components in PAOM, which is in contact with the eyelid through coupling gel during imaging. The ultrasonic transducer plays a crucial role in determining the image quality affected by parameters such as spatial resolution, signal-to-noise ratio, and field of view. In this paper, we present the results of a systematic study on a high-frequency ultrasonic transducer design for PAOM. The design includes piezoelectric material selection, frequency selection, and the fabrication process. Transducers of various designs were successfully applied for capturing images of biological samples in vivo. The performances of these designs are compared and evaluated.

High Performance Relaxor-Based Ferroelectric Single Crystals for Ultrasonic Transducer Applications

Chen, Yan; Lam, Kwok-Ho; Zhou, Dan; Yue, Qingwen; Yu, Yanxiong; Wu, Jinchuan; Qiu, Weibao; Sun, Lei; Zhang, Chao; Luo, Haosu; Chan, Helen L. W.; Dai, Jiyan
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 29/07/2014 EN
Relevância na Pesquisa
46.72%
Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33∼2000 pC/N, kt∼60%) near the morphotropic phase boundary (MPB). Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc) and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array...

Novel Real-Time Temperature Diagnosis of Conventional Hot-Embossing Process Using an Ultrasonic Transducer

Cheng, Chin-Chi; Yang, Sen-Yeu; Lee, Dasheng
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 17/10/2014 EN
Relevância na Pesquisa
46.72%
This paper presents an integrated high temperature ultrasonic transducer (HTUT) on a sensor insert and its application for real-time diagnostics of the conventional hot embossing process to fabricate V-cut patterns. The sensor was directly deposited onto the sensor insert of the hot embossing mold by using a sol-gel spray technique. It could operate at temperatures higher than 400 °C and uses an ultrasonic pulse-echo technique. The ultrasonic velocity could indicate the three statuses of the hot embossing process and also evaluate the replication of V-cut patterns on a plastic plate under various processing conditions. The progression of the process, including mold closure, plastic plate softening, cooling and plate detachment inside the mold, was clearly observed using ultrasound. For an ultrasonic velocity range from 2197.4 to 2435.9 m/s, the height of the V-cut pattern decreased from 23.0 to 3.2 μm linearly, with a ratio of −0.078 μm/(m/s). The incompleteness of the replication of the V-cut patterns could be indirectly observed by the ultrasonic signals. This study demonstrates the effectiveness of the ultrasonic sensors and technology for diagnosing the replicating condition of microstructures during the conventional hot embossing process.

Novel Real-Time Diagnosis of the Freezing Process Using an Ultrasonic Transducer

Tseng, Yen-Hsiang; Cheng, Chin-Chi; Cheng, Hong-Ping; Lee, Dasheng
Fonte: MDPI Publicador: MDPI
Tipo: Artigo de Revista Científica
Publicado em 04/05/2015 EN
Relevância na Pesquisa
46.66%
The freezing stage governs several critical parameters of the freeze drying process and the quality of the resulting lyophilized products. This paper presents an integrated ultrasonic transducer (UT) in a stainless steel bottle and its application to real-time diagnostics of the water freezing process. The sensor was directly deposited onto the stainless steel bottle using a sol-gel spray technique. It could operate at temperature range from −100 to 400 °C and uses an ultrasonic pulse-echo technique. The progression of the freezing process, including water-in, freezing point and final phase change of water, were all clearly observed using ultrasound. The ultrasonic signals could indicate the three stages of the freezing process and evaluate the cooling and freezing periods under various processing conditions. The temperature was also adopted for evaluating the cooling and freezing periods. These periods increased with water volume and decreased with shelf temperature (i.e., speed of freezing). This study demonstrates the effectiveness of the ultrasonic sensor and technology for diagnosing and optimizing the process of water freezing to save energy.

Industrial requirements in high-power ultrasonic transducers for defoaming

Rodríguez, Germán; Acosta Aparicio, Víctor Manuel; Pinto, Alberto; Gallego Juárez, Juan Antonio
Fonte: Sociedad Española de Acústica Publicador: Sociedad Española de Acústica
Tipo: Comunicación de congreso Formato: 263067 bytes; application/pdf
ENG
Relevância na Pesquisa
56.72%
Ponencia presentada en el XIX Congreso Internacional de Acústica (ICA2007), Madrid, 2-7 Sep 2007.-- PACS: 43.35.-c.; Airborne stepped-plate focusing transducers have shown to be an efficient tool for breaking foams. The main characteristics of such transducers are their high efficiency and power capacity as well as their strong focusing effect. As a consequence, by using these power transducers it is possible to generate intensities in the focal area as high as 170 dB. However, for their application to industrial problems a special design has to be done covering specific requirements. The main requirements for industrial applications refer to efficiency, safety, durability and environmental resistance. This paper deals with the design and characterization of an industrial prototype of high power ultrasonic transducer for defoaming which is able to work in continuous operation under adverse environmental conditions, and high power excitation without the use of any cooling system. In addition, the transducer is designed to ensure the safe use of airborne high-power ultrasound according to the international recommendations for occupational exposure limits.; The industrial use of the transducers is for defoaming in bottling and canning lines and in fermenting vessels and other reactors.; The work has been carried out in the frame of the Project: “Adaptation to requirements and industrial standards of an ultrasonic system for foam elimination and control...

Time domain analysis of ultrasonic signals for non-invasive temperature estimation

Salido, Ricardo; Bazán, Ivonne; Ramos, Antonio; Vera, Arturo; Leija, Lorenzo
Fonte: Sociedad Española de Acústica Publicador: Sociedad Española de Acústica
Tipo: Comunicación de congreso Formato: 203333 bytes; application/pdf
ENG
Relevância na Pesquisa
46.66%
Ponencia presentada en el XIX Congreso Internacional de Acústica (ICA2007), Madrid, 2-7 Sep 2007.-- PACS: 43.80.Ev.; A time delay technique that relates the temperature changes with the time shifts (delays) presented in echoes coming from a simulated and experimental body immersed in a thermal bath is developed and analyzed. Both simulated and experimental signals were obtained from a numeric and experimental phantom respectively. Results of the time domain analysis for two transducer frequencies in a temperature interval ranging from 25°C to 42°C are presented. Performance in the technique is evaluated by calculating the correlation coefficient between the lineal regression and the real values obtained for the temperature estimation. A comparison between simulated and experimental data for two transducer frequencies is presented.; This work was supported by the Acoustics Institute (CSIC) in Madrid (R&D National Plan of the Spanish Ministry of Education & Science, Project PN-DPI2005-00124), and the Bioelectronics Section (CINVESTAV) in Mexico. The stay of M. Sc. I. Bazán in CSIC, during 2006, was financed by ALFA-PETRA-II, U.E contract AML/B7-11/97/0666/II-0343 FA-FCD-FI.; Peer reviewed