Results Of Ultrasonic Measurements Research Articles

Calibrating ultrasonic sensor measurements of crop canopy heights: a case study of maize and wheat.

Canopy height serves as an important dynamic indicator of crop growth in the decision-making process of field management. Compared with other commonly used canopy height measurement techniques, ultrasonic sensors are inexpensive and can be exposed in fields for long periods of time to obtain easy-to-process data. However, the acoustic wave characteristics and crop canopy structure affect the measurement accuracy. To improve the ultrasonic sensor measurement accuracy, a four-year (2018-2021) field experiment was conducted on maize and wheat, and a measurement platform was developed. A series of single-factor experiments were conducted to investigate the significant factors affecting measurements, including the observation angle (0-60°), observation height (0.5-2.5 m), observation period (8:00-18:00), platform moving speed with respect to the crop (0-2.0 m min-1), planting density (0.2-1 time of standard planting density), and growth stage (maize from three-leaf to harvest period and wheat from regreening to maturity period). The results indicated that both the observation angle and planting density significantly affected the results of ultrasonic measurements (p-value< 0.05), whereas the effects of other factors on measurement accuracy were negligible (p-value > 0.05). Moreover, a double-input factor calibration model was constructed to assess canopy height under different years by utilizing the normalized difference vegetation index and ultrasonic measurements. The model was developed by employing the least-squares method, and ultrasonic measurement accuracy was significantly improved when integrating the measured value of canopy heights and the normalized difference vegetation index (NDVI). The maize measurement accuracy had a root mean squared error (RMSE) ranging from 81.4 mm to 93.6 mm, while the wheat measurement accuracy had an RMSE from 37.1 mm to 47.2 mm. The research results effectively combine stable and low-cost commercial sensors with ground-based agricultural machinery platforms, enabling efficient and non-destructive acquisition of crop height information.

Formation Model for Acoustic Characteristics of Solid Media with Ordered Fracturing

Introduction. The development of new structural materials and improvement of existing technologies for the production of new products on their basis lead to the emergence of new types of medium discontinuities. Therefore, the development of new models of discontinuities that take the previously ignored parameters into account seems to be relevant for the purposes of nondestructive testing and structural measurements. This concerns, e.g., the roughness of adjacent surfaces of microcrack ordered sets.Aim. Theoretical substantiation for the processes of elastic waves propagation through an elastic medium containing an ordered lattice of microcracks with boundary conditions in the linear slip approximation, modified by taking into account the parameters of micro-convexities of microcrack rough boundaries. Database formation for experimental studies aimed at determining the physical and mechanical characteristics of structural materials.Materials and methods. The acoustic characteristics of materials were determined based on the derivation and solutions of dispersion equations describing the formation and propagation of effective longitudinal, transverse, and Rayleigh surface elastic waves in elastic media with ordered cracking. Their values were also used to determine the effective speed of Rayleigh surface waves.Results. The conducted simulation of elastic wave formation processes showed that an increase in the concentration of microcracks leads to a decrease in the phase velocities of effective longitudinal, transverse, and surface waves, as well as to an increase in the attenuation coefficients at given ultrasound frequencies and material parameters.Conclusion. The radius of the microsphere that replaces the surface micro-convexity and the roughness parameter Rz have a significant impact on the formation of physical and mechanical characteristics of materials, which are determined by the results of ultrasonic measurements. The developed model can be recommended as a basis for interpreting the results of ultrasonic measurements.

Ultrasonic quality assurance for underground salt shotcrete sealing structures in Teutschenthal mine, Germany

Underground sealing structures are necessary to seal radioactive or toxic waste in underground repositories. Particularly developed MgO concrete is used in the mine in Teutschenthal and applied at a large-scale test with the aim to provide concrete with low permeabilities. The test structures (up to 10 m long) were created with the help of a shotcrete procedure. Besides destructive tests, non-destructive ultrasonic measurements are used for quality assurance to monitor potential anomalies such as cracks, concrete inhomogeneities, and delamination. We show results of ultrasonic measurements with a multi-transducer system used at the front site of the concrete structure. Images are obtained by synthetic aperture focusing techniques. Concreting sections are not systematically imaged so that a successful concreting is assumed as also indicated by observed low permeabilities. Several reflectors up to a depth of 1.2 m are identified and interpreted as potential damages in the concrete. Phase analysis of prominent reflectors reveal a negative impedance contrast thus indicating air filled voids, cracks or delamination. Boreholes through some of the identified reflectors are used to verify the results from ultrasonic measurements. Additionally, an experiment with incorporated defects is undertaken to analyse the reliability of the applied methods. Overall, the conducted tests show the great potential of ultrasonic measurements to detect critical anomalies. Despite challenges at small-scale structures (cm-order), large-scale anomalies can be identified. Implementing ultrasonic monitoring during and after the construction of concrete sealing structures is recommended as a tool for quality assurance.

Ultrasonic Study of Molecular Interactions and Compressibility Behaviour of Samarium Soaps in Benzene-DMSO Mixture

Abstract: Ultrasonic measurements of samarium soaps (palmitate and myristate) have been carried out in a mixture of benzene and DMSO (70%-30% v/v) to determine the critical micellar concentration(CMC), soap-solvent interaction and various acoustic parameters. The results show that ultrasonic velocity, intermolecular free length, adiabatic compressibility, adiabatic molar volume and apparent molar compressibility decrease while specific acoustic impedance, relative association and solvation number increase with increase in soap concentration. The results of ultrasonic measurements have also been explained in terms of well-known equations. Keywords: Ultrasonic measurements, molecular interactions, samarium soaps, compressibility, critical micellar concentration(CMC).

The Results of an Experimental Study of the Acoustic Properties of Water-Saturated Sand in the –20 to +20°C Temperature Range

The results of ultrasonic measurements using P- and S-waves on a sample of a fully water-saturated medium-grained sand in a temperature range from –20 to +20°C, viz., the dependences of kinematic and dynamic parameters of an ultrasonic signal on temperature, as well as on the elastic wave attenuation, are presented. The proposed method made it possible to calculate P- and S-wave attenuation on the ultrasonic frequencies for a wide temperature range. The value of the attenuation in the range of negative and positive temperature values differs by a factor of 40–50 for P-waves and by two orders of magnitude for S-waves. A smooth change in the attenuation from –5°C (–10°C) to 0°C was observed for P- (S-) waves. The attenuation that affects the dynamic parameters reacts faster to thawing of frozen ground than the velocity, which is more relevant in the case of plastic frozen rocks and at a temperature close to 0°C.

Results experimantal study of acoustic properties of saturated sand in the temperature range –20 — +20 &lt;SUP&gt;ᵒ&lt;/sup&gt;C

In this article we discuss the results of ultrasonic measurements using p and s waves on a sample of full water–saturated sand in the temperature range –20 ᵒC — + 20 ᵒC. The results are: dependence of kinematic and dynamic parameters of the ultrasonic signal on temperature and elastic waves attenuation parameter. We propose method to calculate the attenuation parameter of p and s waves at ultrasonic frequencies for a wide temperature range. The values of the attenuation parameter at negative and positive temperatures differ by 40–50 times for p waves and by 2 orders of magnitude for s waves. A smooth change in the attenuation parameter from –5 ᵒC (–10 C) to 0 ᵒC for p (s) waves was observed. The attenuation affecting the dynamic parameters reacts faster to the thawing of frozen ground than the waves velocity, which is most relevant in the case of plastic–frozen rocks and at temperatures close to 0.

Comparison of Linear and Nonlinear Ultrasonic Parameters in Characterizing Grain Size and Mechanical Properties of 304L Stainless Steel

Ultrasonic nondestructive techniques can be used to characterize grain size and to evaluate mechanical properties of metals more practically than conventional destructive optical metallography and tensile tests. Typical ultrasonic parameters that can be correlated with material properties include ultrasonic velocity, ultrasonic attenuation coefficient, and nonlinear ultrasonic parameters. In this work, the abilities of these ultrasonic parameters to characterize the grain size and the mechanical properties of 304L stainless steel were evaluated and compared. Heat-treated specimens with different grain sizes were prepared and tested, where grain size ranged from approximately 40 to 300 μm. The measurements of ultrasonic velocity and ultrasonic attenuation coefficient were based on a pulse-echo mode, and the nonlinear ultrasonic parameter was measured based on a through-transmission mode. Grain size, elastic modulus, yield strength, and hardness were measured using conventional destructive methods, and their results were correlated with the results of ultrasonic measurements. The experimental results showed that all the measured ultrasonic parameters correlated well with the average grain size and the mechanical properties of the specimens. The nonlinear ultrasonic parameter provided better sensitivity than the ultrasonic velocity and the ultrasonic attenuation coefficient, which suggests that the nonlinear ultrasonic measurement would be more effective in characterizing grain size and mechanical properties than linear ultrasonic measurements.

Electromagnetic ultrasonic measurement for welding residual stress detection - comparison between experiment with numerical simulation

In order to study the feasibility of electromagnetic ultrasonic method on the welding residual stress detection in Q345R plate, experiments and numerical simulations were carried out. The welding residual stress in the plate was firstly measured by electromagnetic acoustic transducer (EMAT). Then, finite element model of welding process was established to predict the residual stress in plate, who’s rationality was verified by blind hole experiment. At last, the average of numerical simulation results at five points along the plate’s thickness direction was compared with the electromagnetic ultrasonic measurement results. The results show that the residual stress measured by EMAT is consistent with those from numerical simulation in direction of the weld. However, in the vertical direction of the weld, the deviation between EMAT results and numerical simulation is relatively large near the weld fusion line. This phenomenon is also found in the junction between the heat affected zone and the base metal.

Analysis of the couplant influence on the ultrasonic thickness measurement of the steel grade S355J0

The ultrasonic thickness measurement is the most commonly performed technique as a part of quality management of systems and constructions. The paper carries out a study of the couplant impact on the wall thickness ultrasonic measurement results. Experimental samples are made from the steel grade S355J0. By performing a theoretical and experimental analysis, it estimates that there exists a significant effect of the particular parameters of the ultrasound transducer, the couplants type and their interactions on the thickness measurement results. An experiment scheme and the appropriate methodology for experimental results analyses create the preconditions for the assessment of the influence of the couplant type, material thickness and the parameters of ultrasound probe to the measurement uncertainty.

Elastic anisotropy of Tambo gneiss from Promontogno, Switzerland: a comparison of crystal orientation and microstructure-based modeling and experimental measurements

Author(s): Vasin, RN; Kern, H; Lokajicek, T; Svitek, T; Lehmann, E; Mannes, DC; Chaouche, M; Wenk, HR | Abstract: Felsic and mafic gneisses constitute large proportions of the upper and lower continental crust. Gneisses often display high anisotropy of elastic properties associated with preferred orientations of sheet silicates. Here we study the elastic anisotropy of a sample of Tambo gneiss from Promontogno in the Central Alps. We apply optical microscopy, time-of-flight neutron diffraction, neutron and X-ray tomography to quantify mineral composition and microstructures and use them to construct self-consistent models of elastic properties. They are compared to results of ultrasonic measurements on a cube sample in a multi-anvil apparatus and on a spherical sample in an apparatus that can measure velocities in multiple directions. Both methods provide similar results. It is shown that models of microstructure-derived elastic properties provide a good match with ultrasonic experiment results at pressures above 100 MPa. At a pressure of 0.1 MPa the correspondence between the model and the experiment is worse. This may be caused by an oversimplification of the model with respect to microfractures or uncertainties in the experimental determination of S-wave velocities and elastic tensor inversion. The study provides a basis to determine anisotropic elastic properties of rocks either by ultrasonic experiments or quantitative models based on microstructures. This information can then be used for interpretation of seismic data of the crust.

Further investigations of empirical improvements to the Johnson–Champoux–Allard model

Non-acoustical physical parameters (tortuosity, viscous characteristic length, thermal characteristic length, porosity and flow resistivity) of glass fibre, melamine foam, compressed melamine foam and reticulated polyurethane foam materials have been measured. Also tortuosity and two characteristic lengths have been deduced from impedance tube measurements using commercial software (Foam-X). Between 200Hz and 5kHz sound velocities in the materials have been deduced from impedance tube measurements. Between 79kHz and 1MHz they have been deduced from ultrasonic measurements.Predictions of sound velocities based on the Johnson–Champoux–Allard (JCA) model using measured non-acoustical physical parameters and, at high frequency, using ultrasonically-measured non-acoustical physical parameters (tortuosity, viscous characteristic length and thermal characteristic length) are found to be in good agreement with the ultrasonically-measured sound velocities above 100kHz thereby confirming the accuracy of the JCA model at ultrasonic frequencies.Differences in values of the two characteristic lengths between the Foam-X outputs and the results of ultrasonic measurements, using the slope method, and the important role of two correction factors in Kino’s empirical modification of the JCA model are explored in detail. It is shown that the values of characteristic lengths required to fit data using the original JCA model in the audible frequency range differ significantly from the ultrasonically-measured values. However it is shown that the Foam-X and the Kino model methods yield similar values for the two characteristic lengths in the audible frequency range. Further modifications of the JCA model to make it valid over a wider frequency range are proposed.

Characterization of Olive Oil by Ultrasonic and Physico-chemical Methods

Olive oil excels by its nutritional and medicinal benefits. It can be consumed without any treatment. However, its quality can be altered by inadequate storage conditions or if it is mixed with other kinds of oils. The objective of this work is to demonstrate the ability of ultrasonic methods to characterize and control olive oil quality. By using of a transducer of 2.25MHz nominal frequency, in pulse echo mode, ultrasonic parameters, such as propagation velocity and attenuation,have been measured for pure olive oil and for its mixtures with sunflower oil at different proportions. Mechanical properties, such as density and viscosity, have also been determined. The results of ultrasonic measurements are consistent with those obtained by physico-chemical methods, such as rancidity degree, acid index, UV specific extinction coefficient and viscosity. They show that the ultrasonic method allows to distinguish between mixtures at different proportions. The study allows concluding that ultrasound techniques can be considered as a useful complement to existing physico-chemical analysis techniques.

Ultrasonic determination of mechanical properties of meat products

Young’s modulus and Poisson’s ratio values were determined for selected pork coldcuts (canned ham and Podwawelska sausage) based on measurements of sound velocity and the attenuation coefficient in samples, the results of compression tests and sample density measurements. All measurements were performed at 5°C and 20±1°C. Poisson’s ratio for the analyzed products was determined at the indicated temperature based on the measured acoustic parameters, sample density and the value of Young’s modulus calculated in mechanical tests. The average value of Poisson’s ratio was determined 0.49999, and it was similar to the values cited by other authors. The average Poisson’s ratio and the results of ultrasonic measurements were used to calculate Young’s modulus. At 5°C, the average Young’s modulus values for canned ham and Podwawelska sausage were determined at 185.3 and 148.2kPa, respectively, in the compression test, and at 193.1 and 145.4kPa, respectively, in ultrasonic measurements. At 20°C, the above values were determined at 151.4 and 99.9kPa, and at 147.2 and 86.1kPa, respectively. Young’s modulus values calculated based on acoustic measurements did not differ significantly from the values determined based on the results of mechanical tests.

Magnetoelastic couplings in the distorted diamond-chain compound azurite

We present results of ultrasonic measurements on a single crystal of the distorted diamond-chain compound azurite ${\mathrm{Cu}}_{3}$(${\mathrm{CO}}_{3}$)${}_{2}$(OH)${}_{2}$. Pronounced elastic anomalies are observed in the temperature dependence of the longitudinal elastic mode ${c}_{22}$ which can be assigned to the relevant magnetic interactions in the system and their couplings to the lattice degrees of freedom. From a semiquantitative analysis of the magnetic contribution to ${c}_{22}$ the magnetoelastic coupling $G=\ensuremath{\partial}{J}_{2}$/$\ensuremath{\partial}{\ensuremath{\epsilon}}_{b}$ can be estimated, where ${J}_{2}$ is the intradimer coupling constant and ${\ensuremath{\epsilon}}_{b}$ the strain along the intrachain $b$ axis. We find an exceptionally large coupling constant of $|G|\ensuremath{\sim}$ 3650 K highlighting an extraordinarily strong sensitivity of ${J}_{2}$ against changes of the $b$-axis lattice parameter. These results are complemented by measurements of the hydrostatic pressure dependence of ${J}_{2}$ by means of thermal expansion and magnetic susceptibility measurements performed both at ambient and finite hydrostatic pressure. We propose that a structural peculiarity of this compound, in which ${\mathrm{Cu}}_{2}$${\mathrm{O}}_{6}$ dimer units are incorporated in an unusually stretched manner, is responsible for the anomalously large magnetoelastic coupling.

Ultrasonic Evaluation of Welding Residual Stresses in Stainless Steel Pressure Vessel

This paper investigates ultrasonic method in stress measurement of a pressure vessel made of austenitic stainless steel 304 L. Longitudinal critically refracted (LCR) waves are employed to measure the welding residual stresses. The acoustoelastic constant is measured through a hydro test while the pressure vessel is kept intact. Hole-drilling method is used to verify the results of ultrasonic measurement corresponding to axial and hoop residual stresses of the pressure vessel. The results show good agreement between hole-drilling and ultrasonic stress measurements which is accomplished nondestructively.

Anterior Segment Parameters Measured with 2 Optical Devices Compared to Ultrasonic Data

Ophthalmic parameters can be measured with different techniques and devices. Our aim was to measure anterior segment parameters using 2 optical devices and to compare the data to ultrasonic technique. Axial length (AL) was measured with IOLMaster; anterior chamber depth (ACD) was determined using IOLMaster, Visante® optical coherence tomography (OCT), and Pentacam® HR; and central corneal thickness (CCT) were measured with Pentacam® HR and with ultrasound. In 45 eyes of 45 patients (age 62.73±15.31), the AL was 23.35±1.49 mm. The CCT was 541.7±39.9 µm with Visante OCT, 549.7±39.2 µm with Pentacam® HR, and 534.3±41.3 µm with ultrasonic device. The ACD was 3.0±0.42 mm with IOLMaster, 3.26±0.95 mm with Visante OCT, and 3.06±0.41 mm with Pentacam® HR. In case of CCT measurements, data obtained with Pentacam HR correlated with the results of ultrasonic measurements (r=0.89; p<0.001) and Visante OCT measurements (r=0.88; p<0.001). Regarding ACD results, a significant correlation was observed between Pentacam HR and IOLMaster (r=0.95; p<0.0001) but they did not significantly correlate to Visante OCT data (r=0.23; p=0.12). Correlation was significant between AL and ACD measured with IOLMaster (r=0.67; p<0.001). The CCT and ACD data show strong correlation between different devices.

Assessment of Intergranular Corrosion Attack in Austenitic Stainless Steel Using Ultrasonic Measurements

The structural materials of reprocessing and waste management plants are made from AISI Type 304L (UNS S30403) grade austenitic stainless steels and are prone to localized corrosion attack like intergranular corrosion (IGC). It is very important to detect and characterize this attack non-destructively. An ultrasonic-based, non-destructive evaluation technique has been developed to detect and estimate the depth of IGC attack in Type 304 (UNS S30400) stainless steel grade plate. Samples with varying degrees of IGC attack were generated in laboratory and used for this study. Ultrasonic measurement involved determination of sound velocity in longitudinal mode, longitudinal to shear velocity ratio, sound attenuation measurement, and spectral analysis. The elastic modulus measurement using a nano-hardness tester was carried out to formulate the basis of change in sound velocity in the IGC-attacked samples as compared to the virgin sample. This paper gives the details on the sample preparation method used for generation of IGC attack in Type 304 stainless steel plate and reports the results of ultrasonic measurement on the characterization of IGC attack. The results are compared with maximum depth of IGC attack estimated by microscopic examination.

Ultrasonic evaluation of spall damage accumulation in aluminum and steel subjected to repeated impact

This paper shows that the spall damage accumulated in target plates during repeated impact tests can be effectively evaluated by invoking ultrasonic techniques. The experimental data obtained for commercially available, pure aluminum and medium carbon steel subjected to three times repeated plate impact test, serve as a proof of efficiency and accuracy of our method. The spall damage was evaluated using a low frequency scanning acoustic microscope (C- and B-scan images) as well as measurement of ultrasonic velocity, attenuation (amplitude change of B2–B1 echo) and backscattering intensity. We provide here a detailed account of the damage history in essentially ductile aluminum. This proves that the voids nucleated during the first impact form the defect array undergoing coalescence when the stress of second impact is lower than the level applied in the first one. The case of aluminum contrasts the behavior of carbon steel, governed by the development of microcracks generated already during the initial impact. Our conclusions are based on the output of B- and C-scan images consistent with the results of ultrasonic measurements. While providing insights into the evolution of the spall damage, the non-destructive ultrasonic technique promoted by the present authors offers advantages of efficiency, direct applicability to the components of commercial structures, and for early damage prediction.

Transformation of the spectrum of wave geophysical signals in nonlinear media

The nonlinear behavior of acoustic and electromagnetic impulses in structurally heterogeneous and heterophase media is considered. The example of a signal amplitude spectrum shift to the low-frequencies is studied. The laboratory results of ultrasonic measurements and georadar field data are presented.

Complete sets of elastic constants and photoelastic coefficients of pure and MgO-doped lithium niobate crystals at room temperature

This paper presents the results of ultrasonic measurements of LiNbO3 and LiNbO3:MgO crystals. The tensors of piezoelectric coefficients, elastic stiffness constants, and elastic compliances are determined for both crystals at room temperature. Combining these data with the results of piezo-optical measurements, a complete set of photoelastic tensor coefficients is also calculated. Doping of LiNbO3 crystals by MgO does not lead to a considerable modification of their elastic and photoelastic properties. However, LiNbO3:MgO is characterized by a considerably higher resistance with respect to powerful light radiation, making it promising for future application in acousto-optic devices that deal with superpowerful laser radiation. Presented here are the complete tensor sets of elastic constants and photoelastic coefficients of LiNbO3 and LiNbO3:MgO crystals that may be used for a geometry optimization of acousto-optical interaction providing the best diffraction efficiency of acousto-optical cells made of these materials.