Ultrasonic Measurement System Research Articles

Numerical simulation of damage detection using laser-generated ultrasound

Laser ultrasonic techniques have been widely investigated due to its high spatial resolution and capacity for remote and noncontact measurement. In this study, the laser induced ultrasonic wave on an aluminum plate is simulated, and a nonlinear feature is used to detect a micro crack introduced in the plate model. A multi-physics simulation is conducted and optimized considering the effect of thermal diffusion. A nonlinear feature, called Bhattacharyya Distance (BD), is calculated to show the crack-induced geometric difference among the state space attractors obtained from closely spaced measurement points near the crack. First, a 3D model is built, and its simulation result is compared with an experiment performed using a noncontact laser ultrasonic measurement system. Then, by creating a micro crack in the model, BD is extracted and the crack is successfully detected and visualized. Finally, the effects of BD parameters, such as embedding dimension and frequency band, on damage visualization are investigated.

Delamination localization in wind turbine blades based on adaptive time-of-flight analysis of noncontact laser ultrasonic signals

In this study, a two-level scanning strategy for a noncontact laser ultrasonic measurement system is proposed to expedite the inspection of a wind turbine blade. First, coarse scanning of the entire blade is performed with a low spatial resolution for initial delamination localisation. Then, dense scanning with a high spatial resolution is performed only within the identified delaminated region for delamination visualization. This study especially focuses on the initial delamination localisation using adaptive coarse scanning. Laser ultrasonic responses from two pitch-catch paths, names inspection pairs, are obtained within a specified coarse scanning grid. Then, potential delamination locations within the given grid are estimated through time-of-flight analysis of delamination reflected waves. Once potential delamination locations are estimated, new inspection pairs are placed near the potential locations for precise localisation. These steps are repeated for every coarse scanning grids on the target wind turbine blade. The feasibility of the proposed technique for rapid delamination detection is demonstrated with a 10 kW glass fibre reinforced plastic wind turbine blade.

Synchronization Technique for Doppler Signal Extraction in Ultrasonic Vibration Measurement Systems

Doppler signal extraction through a synchronization technique is proposed for ultrasonic vibration measurement systems, which employ a pair of transducers and a vibrating object. Due to Doppler effect, the received ultrasonic signal is phase modulated. The moving window filter (MWF) tuned for the center frequency of the carrier converts phase-modulated signal into amplitude-modulated signal because of the carrier frequency variation. To retrieve the vibrating object information, the proposed technique based on MWF synchronizes its output with the phase-modulated received signal so that it can accurately track the carrier variation. The synchronization is achieved through adaptive sampling frequency adjustment. With ultrasonic carrier tracking, the Doppler signal is retrieved that carries the vibration amplitude and frequency information. The simulation results are validated through experimental investigation carried out for wide variation of the carrier by digital implementation.

Inline Measurement of Particle Concentrations in Multicomponent Suspensions using Ultrasonic Sensor and Least Squares Support Vector Machines.

This paper proposes an ultrasonic measurement system based on least squares support vector machines (LS-SVM) for inline measurement of particle concentrations in multicomponent suspensions. Firstly, the ultrasonic signals are analyzed and processed, and the optimal feature subset that contributes to the best model performance is selected based on the importance of features. Secondly, the LS-SVM model is tuned, trained and tested with different feature subsets to obtain the optimal model. In addition, a comparison is made between the partial least square (PLS) model and the LS-SVM model. Finally, the optimal LS-SVM model with the optimal feature subset is applied to inline measurement of particle concentrations in the mixing process. The results show that the proposed method is reliable and accurate for inline measuring the particle concentrations in multicomponent suspensions and the measurement accuracy is sufficiently high for industrial application. Furthermore, the proposed method is applicable to the modeling of the nonlinear system dynamically and provides a feasible way to monitor industrial processes.

Vibration parameter estimation methods for ultrasonic measurement systems – a review

A review of vibration signal estimation techniques employed in ultrasonic vibration measurement systems is presented. The review focuses on the Doppler signal extraction methods including the theory and analysis pertaining to the background of ultrasonic vibration measurement techniques. The phase modulated received signal in the vibration measurement system involves constant phase shift because of ultrasonic path length, phase shift introduced by Doppler effect because of vibrating object and the parametric phase shift caused by interaction of high frequency ultrasonic wave and low pressure developed by vibrating object. Among the three phase shifts, the Doppler phase shift contains the vibrating signal information and the extraction of Doppler signal helps in knowing the velocity of the vibrating object, amplitude and phase of the vibration. Various techniques of Doppler phase shift retrieval are categorised based on the modulation index estimation procedures from the received ultrasonic signal. An analysis is made based on the information retrieval methods for estimation of vibration signal parameters, range of the vibration amplitude, frequency and the preferable carrier frequency for transmission. Further, the analysis also presents various applications in which ultrasonic vibration measurements system are employed successfully.

Numerical and Experimental Study for Unsteady Oil Film Thickness of the Rotating Cylinder Chamber Wall

The oil film thickness on the bearing chamber wall directly affects the wall heat transfer efficiency, so a fundamental study on the motion of oil film on the rotating cylinder has been conducted to this end. On the one hand, the rotating cylinder test rig was designed, and an ultrasonic measurement system was established to measure the dynamic oil film thickness. On the other hand, the unsteady oil film heat and mass transfer movement model was also established, and the numerical simulation to solve oil film motion by using computational fluid dynamic (CFD) commercial software was carried out. Meanwhile, on the basis of study on the oil film formation process and film thickness verification, the oil film distributions on the chamber wall with rotation speed and oil flow rate were analyzed and studied. Results show that the oil film on the rotating chamber wall experiences a development process from the oil film formation to basic stability, about 1.0 s in this paper. And comparison between the numerical and experimental data shows that the maximum error between experimental data and numerical simulation is 7.76%. Moreover, for the oil film distributions in the stable state, oil film thickness shows a trend of decreasing with the increasing of rotation speed, but increasing with the increasing of oil flow rate. The research here will provide the basis for subsequent study of the interaction between oil film motion and the wall heat transfer.

An Ultrasonic System for Determining Mango Physiological Properties

There is an increasing requirement for high qualityfruits such as mango. Hence it is vital to have a fast, accurate andreliable method for measuring and monitoring the quality of fruitfrom the field to the consumer. This paper presents aninvestigation on the use of an ultrasonic measurement system fordetermining the quality of mango.

Lower Extremity Joint Angle Tracking with Wireless Ultrasonic Sensors during a Squat Exercise.

This paper presents an unrestrained measurement system based on a wearable wireless ultrasonic sensor network to track the lower extremity joint and trunk kinematics during a squat exercise with only one ultrasonic sensor attached to the trunk. The system consists of an ultrasound transmitter (mobile) and multiple receivers (anchors) whose positions are known. The proposed system measures the horizontal and vertical displacement, together with known joint constraints, to estimate joint flexion/extension angles using an inverse kinematic model based on the damped least-squares technique. The performance of the proposed ultrasonic measurement system was validated against a camera-based tracking system on eight healthy subjects performing a planar squat exercise. Joint angles estimated from the ultrasonic system showed a root mean square error (RMSE) of 2.85° ± 0.57° with the reference system. Statistical analysis indicated great agreements between these two systems with a Pearson's correlation coefficient (PCC) value larger than 0.99 for all joint angles' estimation. These results show that the proposed ultrasonic measurement system is useful for applications, such as rehabilitation and sports.

Void Fraction Detection in a Gas-Liquid Two-Phase Flow Using a Propagation Attenuation Method

Based on the principle of the attenuation of an acoustic wave propagating in a gas-liquid two-phase flow, an experiment has been designed to measure the void fraction. The experiment system is consisted of three segments which arepressure stabilizing control system, ultrasonic measurement system and bubble injection system. The measurement process is three steps. First, a reference experiment is performed to acquire the received signal amplitude in pure liquid. Then, measurement of the received signal amplitude in different void fraction is accomplished. Last, the relationship between void fraction and signal amplitude attenuation is given on which the void fraction of two-phase flow can be detected. It is confirmed that void fraction detection using the present method achieves successfully.

Estimation of in vivo cortical bone thickness using ultrasonic waves.

To verify the measurement of cortical bone thickness at the distal radius in vivo using an ultrasonic method. The method for estimating cortical bone thickness was derived from experiments with in vitro bovine specimens. Propagation time of echo waves and propagation time of slow waves were used for the estimation. The outside diameter of cortical bone and the cortical bone thickness at the distal 5.5 % site of radius were measured with the new ultrasonic bone measurement system, and the results were compared with X-ray pQCT clinical measurements. There was a high positive correlation (r: 0.76) between the cortical bone thickness measured by the new ultrasonic system and the X-ray pQCT results. We will be able to measure not only cancellous bone density but also cortical bone thickness in vivo using ultrasonic waves (without X-ray) safely and repeatedly.

New Methods and Transducer Designs for Ultrasonic Diagnostics and Therapy

Recent advances in the field of physical acoustics, imaging technologies, piezoelectric materials, and ultrasonic transducer design have led to emerging of novel methods and apparatus for ultrasonic diagnostics, therapy and body aesthetics. The paper presents the results on development and experimental study of different high intensity focused ultrasound (HIFU) transducers. Technological peculiarities of the HIFU transducer design as well as theoretical and numerical models of such transducers and the corresponding HIFU fields are discussed. Several HIFU transducers of different design have been fabricated using different advanced piezoelectric materials. Acoustic field measurements for those transducers have been performed using a calibrated fiber optic hydrophone and an ultrasonic measurement system (UMS). The results of ex vivo experiments with different tissues as well as in vivo experiments with blood vessels are presented that prove the efficacy, safety and selectivity of the developed HIFU transducers and methods.

Verifying the Melting Behavior in Single-Screw Plasticization Units Using a Novel Simulation Model and Experimental Method

Abstract We report on the development of a novel non-invasive ultrasonic measurement system for determining the melting behavior in a single-screw plasticization unit (35/22D) and on a modified drag-induced melt removal model that builds upon that by Tadmor and Gogos (2006). The solid bed to melt pool ratio is quantified using a non-invasive ultrasonic system based on reflection measurements. Automated analysis of the reflected pulses – measured at different axial positions along the barrel – allows the melting process to be monitored online. Our analysis of the delay section incorporates viscous dissipation into Tadmor's drag-induced melt removal model. We link temperature profile and melt film thickness via differential equations and consider viscous dissipation. By segmenting the delay section in the axial direction, the temperature dependency of the thermo-physical material properties is also considered. Using the melting behavior measured for different materials, we verified the mathematical model. Additionally, the effect of reduced screw length on the plasticization process, important for the injection molding process, was investigated.

Research of Ultrasonic Distance Measurement System Based on Pseudo Random Digital Correlation

An ultrasonic distance measuring system is designed by using MC9S12DG128 microcomputer in this paper. To improve the measuring distance and accuracy, the ultrasonic signal can be modulated with pseudo random binary sequence, and time of flight (TOF) can be determined by calculating the cross-correlation function of the transmission signal and its echo signal. What’s more, the two-step correlation method is adopted in order to reduce the computational complexity. The experiments show that absolute error of the measuring equipment is less than 5 millimeter within the range of 1-5 meter.

The Design of Ultrasonic Distance Measurement System for Auto Reversing Anti-Collision

This paper introduces the working principle, hardware and software designs of ultrasonic distance measurement based on STC89C52RD MCU. The hardware mainly consists of ultrasonic module, liquid crystal display module, alarm module and function key circuit. The system can clearly display the measurement results with high accuracy and can be applied to auto reverse anti-collision alarm system.

Research of Long Range Accurate Ranging Technology Based on Ultrasonic Sensor Measurement

In order to meet the requirements of long range obstacle measurement of tower crane safety warning system and accurately estimate time of flight ( TOF ), an ultrasonic long range measurement system is designed and a mathematical model of echo envelope is established in this paper. Experimental data of long range obstacle measurement were collected and analyzed by using traditional threshold method and cross correlation method, the results exposed low accuracy and poor stability problems. According to the obstacle target can be quickly located by echo peak, and echo signal time domain waveform characteristics can be reflected by envelope model method, an improved long range measurement algorithm based on combination of peak method and envelope model method is introduced. Experimental results show higher accuracy and better stability of the improved long range measurement algorithm compared with threshold method and cross correlation method

Influence of the circumferential wave on the fast and slow wave propagation in small distal radius bone

An ultrasonic system is good for the evaluation of children because its noninvasiveness. The ultrasonic bone measurement system LD-100 has been developed on the basis of the principle of the fast and slow wave phenomenon in the wrist bone. In the measurement of small bones such as those of children, there are some problems due to the influences of circumferential waves on the fast and slow waves. When the diameters of the focused transducers were small, the appearance of the circumferential wave around the cortical bone became late, and it could avoid one of the influences of the circumferential waves.

A Hybrid Bender Element–Ultrasonic System for Measurement of Wave Velocity in Soils

In recent years, the determination of the small strain modulus of soils from laboratory measurement of the elastic wave velocity has become more common. Piezoelectric elements are used in these tests, with two types of configurations: fixed to the back face of a platen as an ultrasonic transducer, or as a bimorph that slightly protrudes out of the platen. A survey of the literature shows that bender/extender elements are more widely used than ultrasonic transducers in soil tests. However, bender/extender elements are invasive in nature. Besides introducing some degree of specimen disturbance, they need to be sufficiently robust for insertion into the soil specimen, and they also need to be properly waterproofed to avoid short-circuiting. Ultrasonic transducers can solve the above-mentioned problems. However, the detection of shear waves can be challenging in soils, as reported in the literature. The objectives of this paper are to examine the difficulties of shear wave detection by ultrasonic transducers and to propose a hybrid bender element–ultrasonic system that partially alleviates the problems associated with bender/extender elements while still providing reliable shear wave velocity measurement. The hybrid system used was calibrated with standard materials, and tests were conducted on sand and kaolin specimens. Relative to bender/extender elements and ultrasonic transducers, the hybrid system showed better performance in determining wave velocities in soil tests, especially for shear waves.

Ultrasonic monitoring of the early-age hydration of mineral admixtures incorporated concrete using cement-based piezoelectric composite sensors

The early-age hydration processes of concretes with mineral admixtures have been monitored and evaluated by a newly developed ultrasonic method based on embedded cement-based piezoelectric composite sensors. With the embedded ultrasonic (P-wave) measurement system, the waveform, wave velocity, attenuation coefficient index, and frequency-domain spectrum of detected ultrasonic waves during hydration can be recorded. The mineral admixtures examined include fly ash, slag, and silica fume, which replace part of the cement in concrete mixtures. It is found that the ultrasonic transmission parameters can be related to the microstructure changes of the concrete. Both the acceleration effects of silica fume and the retardation effects of fly ash and slag on the early hydration of concrete can be determined and explained through the analysis and comparison of the characteristics of the velocity curves. The attenuation coefficient index curve provides additional observation for the study of hydration kinetics. Moreover, the function of fresh concrete in filtering the high-frequency component of the wave varies with time, and concrete can be considered as low-pass frequency spectral filter. Frequency spectra analysis at different ages of fresh concrete provides useful information to reveal the early-age hydration process.

Research on Making Constant Valve Block of Residual Compressive Stress Based on Ultrasonic Testing

We proposed a new method of measuring the residual stress for the component based on the acoustoelastic theory and focused on a new technology of making constant value block of residual stress by shot peening in order to solve problems of residual stress testing by ultrasound. Monitored the residual stress value of block by self-developed ultrasonic residual stress measurement system. The results indicate that the value of the test block changes not much, so it can provides a new way to improve the ultrasonic testing of residual stress.

The effects of a temporarily manipulated dental occlusion on the position of the spine: a comparison during standing and walking

Background contextThe relationship between dental occlusion and body posture or even the spine position is often analyzed and confirmed. However, this relationship has not been systematically investigated for standing and walking. PurposeTo examine whether a symmetric or asymmetric dental occlusion block, using 4 mm thick silicon panels, can significantly change the spine position (cervical, thoracic, or lumbar region) during standing and walking. Study designThe following study is a cross-sectional study. Patient sampleThis study was carried out with 23 healthy subjects (18 women, 5 men) without discomfort in the temporomandibular system or body movement apparatus. Outcome measuresPosition changes (millimeter) of the spine (cervical, thoracic, lumbar) in frontal, sagittal, and transverse planes of motion. MethodsThe upper spine position was quantified with an ultrasonic distance measurement system (sonoSens Monitor). Every subject placed the 4 mm thick silicon panel systematically between the left/right premolars or the front teeth. Differences between the habitual and manipulated occlusion positions were determined by the Friedman test, followed by pairwise comparisons with applied Bonferroni-Holm correction. ResultsDuring standing and walking there were significant (p≤.05) differences between the occlusion block conditions and the habitual dental position in all body planes except in the right lumbar region during walking. In addition, differences within the manipulated occlusion position could be detected. Significant differences were also shown between the standing and walking trials in the frontal, sagittal, and transverse planes, particularly with respect to the lumbar region (p≤.001). ConclusionsSymmetrical and asymmetrical occlusion blocks in the premolar region can be associated with changes in all three spine regions during standing and walking. The results showed highly similar reaction patterns in all spine positions, regardless of the location of the silicon panel. Between standing and walking, the main differences were in the lumbar spine. The results suggest a relationship between the chewing and the movement system. However, it must be stated that this study has no direct clinical impact. The study design cannot determine the causality of the observed associations; also the clinical significance of the small postural changes remains unknown.