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In this paper we examine the creation of a special probe waveform that, when applied to an emitting transducer at location A, results in a strong received signal at that transducer at a particular later time only when a scattering center is present at location B. The probing waveform can be calculated directly from the Green's function for propagation from A to B. Such a probe waveform can be used...
Using ultrasonic guided waves (GW) to assess fractures in long bones has gained considerable attention. This paper focuses on using an improved hybrid boundary element method (HBEM) to analyze and calculate reflection coefficients (RC) and transmission coefficients (TC) of low-order GWs for cracks with different depth-to-width ratios (d/w) in fractured long bones. The results showed that the primary...
In this paper, an approach for the extraction of quantitative parameters from multi-directional ultrasound echo signal data for the differentiation and characterization of specular reflections and diffuse backscattering is presented and evaluated. Spatially resolved, tissue-characterizing parametric images are calculated by analyzing the envelope of echo signals from different insonation angles. Frames...
In the present study, Several 4.5 MHz LFE devices with different electrode configurations, including the dual-gap electrode, single-turn Archimedes spiral electrode, two-turn Archimedes spiral electrode and two-turn symmetric spiral electrode, were fabricated and tested. A common LFE device with the single-gap electrode is also fabricated for comparing their performances. A major resonance peak was...
This paper presents a passive and remote polymer- coated Love wave chemical sensor. A ST-90degX quartz was used as the substrate, which provides a shear horizontal surface acoustic wave (SH-SAW) with high shear velocity and larger piezoelectricity. A layer of polymethylmethacrylate (PMMA) was considered as the guiding layer owing to its lower shear velocity. The dispersion relationship of the Love...
This paper is to derive the reflection and transmission coefficients of Lamb waves incident on a rectangular crack in an elastic plate by means of small local matrices. The repeated and sequential scattering phenomenon at the crack is analyzed by introducing three independent processes according to the boundary shape of the crack and the direction of the wave propagation. Several local wave form matrices...
A SAW ladder filter can consist up to 10 resonators. To avoid the interaction between resonators, they are placed in separate acoustic tracks and that increased the sizes and makes interconnection between resonators long and complex. This paper introduces a method to place 2 or more resonators in one acoustic track with common reflectors and connect them parallel or serial electrically. Ladder filter...
In the area of process control, non-destructive testing (NDT) using ultrasound is valuable due to its noninvasive properties. In process control, imaging of surface profiles is used to locate defects or problematic areas in order to quickly steer the manufacturing process on track again. This paper presents a method for imaging of parallel thin layers within multi-layered structures. Due to the application...
By viewing the quasi-periodicity as the deviation from the periodicity in a particular way, the quasi phononic crystal that has quasi-periodicity (Fibonacci sequence) in one direction and translational symmetry in the other direction is considered. The band structures are characterized by localization factors which are calculated by using the plane-wave-based transfer-matrix method. The results show...
SPUDT cells including two fingers only are hitherto known for so-called NSPUDT directions. In this case, usual solid-finger cells are used. The purpose of the present paper is to find SPUDT cell types consisting of two fingers only for pure mode directions. Moreover, SPUDT cells composed of two fingers suited to complete imperfect NSPUDT behavior or to compensate that are to be found. TF cells for...
Micromachined thin film plate acoustic wave resonators (FPAR) utilizing the lowest order symmetric Lamb wave (S0) propagating in highly textured 2 mum thick Aluminum Nitride (AlN) membranes have been successfully demonstrated. However, a notable drawback of the proposed devices is their non-zero temperature coefficient of frequency (TCF) which lies in the range -20 ppm/K to -25 ppm/K. In this work...
In order to obtain the exact time delay of pulses in the surface acoustic wave (SAW) based radio frequency identification (RFID) at unknown temperature, we propose a method for obtaining a high phase ambiguity resolution by measuring group delays and constructing some restriction on the exact positions of reflectors. To define the restriction parameters for a SAW RFID system with large code capacity...
The objective of this work is to develop an easy-to-build and robust setup for measuring the nonlinearity parameter B/A in fluids using ultrasound. The method is based on the pulse echo technique, using a single element broadband acoustic transducer, and requires electrical signal measurements. Results obtained in water and denatured alcohol validate the proposed procedure. The choice of a suitable...
This paper studies acoustic waves in a water layer enclosed between the YZ-LiNbO3 substrate coated with a thin SiO2 layer and the half-infinite domain occupied by silicone rubber. The plane wave spectrum is computed. Numerical estimations are made of the COM-parameters describing a periodic grating deposited on the LiNbO3 substrate under the SiO2 layer. The dependence of the COM-parameters is investigated...
Surface acoustic wave (SAW) RFID tags are promising devices for the identification of work pieces in an industrial environment. Their practicality was tested using different types of ID tags operating in the 2.45 GHz ISM band with a code volume of 220- 236. The tags were produced to withstand temperatures up to 350degC. The performance was assessed by measuring the probability of identification as...
Through theoretical calculations using the extended Christoffel-Bechmann method and experiments, three operation modes of the LFE devices, which were referred to as the pure-LFE, quasi-LFE and pseudo-LFE modes, were presented. Several about 5 MHz LFE devices with similar geometry using the (yxl)-58deg LiNbO3, (yxl)-16.51deg LiTaO3 and AT-cut quartz crystals were fabricated for analyzing three LFE...
The study of the reflection of ultrasonic waves from a solid-solid interface can be used to measure the thickness between two solid interfaces. This paper describes the theoretical analysis and experimental research of the lubricant film thickness measurement through using normal incidence ultrasonic reflection. The proportion of the incident wave which is reflected at the interface was measured as...
Consolidation mechanisms for colloidal suspensions are currently inadequately characterized due to lack of suitable experimental techniques. We contributed to this question by combining ultrasonic and optical measurements. White light specular and diffuse reflection measurements provided information about colloidal film formation, i.e. the stage of drying and its structure while a concurrent ultrasound...
Main theory results concerned with bulk elastic wave reflection/refraction on the boundary between two piezoelectric crystals subjected to the action of bias electric field or mechanical stress have presented. Some calculations for LiNbO3 and Bi12GeO20 crystals have made.
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