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Knowledge of thermodynamic properties of aqueous solutions of CO2 is crucial for various applications including climate science, carbon capture, utilisation and storage (CCUS), and seawater desalination. However, there is a lack of reliable experimental data, and the equation of state (EOS) predictions are not reliable, particularly for sound speeds in low CO2 concentrations typical of water resources. For this reason, we have measured speeds of sound in three different aqueous solutions containing CO2. We report speeds of sound in the single-phase liquid region for binary mixtures of water and CO2 for mole fractions of CO2 of 0.0118, 0.0066 and 0.0015 at temperatures from 273.15 K to 313.15 K and at pressures up to 50 MPa, measured using a dual-path pulse-echo apparatus. The relative standard uncertainties of the sound speeds are 0.05 %, 0.03 % and 0.01 % at 0.0118, 0.0066 and 0.0015 CO2 mole fractions, respectively. The change in sound speeds as functions of composition, pressure and temperature are analysed in this study. We find that dissolution of CO2 in water increases its sound speeds at all conditions, with the greatest increase occurring at the highest mole fractions of CO2. Our sound speed data agree well with the limited available experimental data in the literature but deviate from the EOS-CG of Gernert and Span by up to 7 % at the lowest temperatures, highest pressures, and highest CO2 mole fraction. The new low-uncertainty sound speed data presented in this work could provide a basis for development of an improved EOS and in establishing reliable predictions of the change in thermodynamic properties of seawater-like mixtures due to absorption of CO2 gas. [ABSTRACT FROM AUTHOR]

Sound speed and elastic constants measurements in solids and liquids are commonly performed using the ultrasound pulse-echo technique. Recent advances have expanded the use of this technique at numerous high pressure synchrotron beamlines and offline laboratories. However, the increased experimental throughput has revealed many limitations in existing software for handling the rapid measurement and the subsequent data-reduction. We report the development of a collection of computer programs for sound speed measurements using the ultrasound pulse-echo technique, compatible with stepped multi-frequency, as well as broadband-pulse, couplant-corrected methods. The programs provide a highly interactive graphical interface, enable efficient measurement, exploration and near real-time analysis of the ultrasound data, and contain features useful for working with samples under high pressure and/or high temperature. The included analysis programs can alleviate the time required for data reduction from hours to less than a minute, allowing users to make timely and informed decisions regarding the appropriate experimental parameters. [ABSTRACT FROM AUTHOR]

Ultrasonic ranging has been widely used in automobiles, unmanned aerial vehicles (UAVs), robots and other fields. With the appearance of micromachined ultrasonic transducers (MUTs), the application of ultrasonic ranging technology presents a more extensive trend. This review focuses on ultrasonic ranging technology and its development history and future trend. Going through the state-of-the-art ultrasonic ranging methods, this paper covers the principles of each method, the signal processing methodologies, the overall system performance as well as key ultrasonic transducer parameters. Moreover, the error sources and compensation methods of ultrasonic ranging systems are discussed. This review aims to give an overview of the ultrasonic ranging technology including its current development and challenges. [ABSTRACT FROM AUTHOR]

Thin-walled tubes and pipes are employed in industries to work under the conditions of high temperature, high pressure, high flow rates and radiation. Due to such stresses and harsh working conditions, tubes lead to sag during operation because of its low Wall Thickness and smaller diameters. There is a requirement to accurately measure sag and dimensions and assess the health and remaining life of tubes and pipes, as per the relevant safety and reliability standards. Sag measurement is a complex task as it has to be performed in-situ. Other than that there is an important requirement to accurately measure Inner Diameter (ID), Outer Diameter (OD) and Wall Thickness (WT) of tubes and pipes. In this paper, a novel type of linear array-based sag and dimension measurement scheme has been proposed for the thin-walled tubes and pipes using Ultrasonic Testing (UT). UT technique has also been employed to accurately measure the sag and dimensions of the thin-walled tubes and pipes. The operating principle of UT is majorly based on Water-Immersion mode for the measurement of sag and dimensions by acquiring Time of Flight (TOF). In this paper, experimentation has been carried out using an in-house developed 4-Channel Ultrasonic Imaging System and using water-immersion mode. The 4-Channel Ultrasonic Imaging System along with an inspection head carrying a novel arrangement of ultrasonic transducers for measurement of sag and dimensions have been utilized. This paper provides details of the sag and dimension measurement of the sample tube and pipe, using the 4-Channel Ultrasonic Imaging System. [ABSTRACT FROM AUTHOR]

The correlation in bone microstructure for ultrasound pulse echo technique is still less accurate compared to through transmission technique. Previous works demonstrated, reflected two modes wave has significant association with bone porosity. The paper aims is to conduct simulation using pulse echo technique to examine the relationship between fast and slow waves with porosity of 2-dimensional cancellous bone models by comparing the result to through transmission technique. The "incident" and "reflected" waves were separated using bandlimited deconvolution method by estimating time threshold of fast and slow waves' transfer function. The parameters of the waves were computed, plotted versus porosity for six different thicknesses and the correlation coefficients between them were compared. The incident and reflected fast wave attenuations show marginally significant correlation with porosity for both bone models orientations. Wave propagation for parallel orientation dominated by incident and reflected fast wave, meanwhile, perpendicular orientation dominated by incident slow wave. The thickness factor affected wave amplitude but less affected the attenuation. Because of propagation loss, reflected wave shows lower correlation to porosity compared to incident wave. Hence, analyzing fast and slow waves might improve the measurement accuracy of pulse echo technique compared to using single mode wave to estimate bone quality. [ABSTRACT FROM AUTHOR]

In this research, the influence of steel bars in the detection of voids in concrete elements using the ultrasonic pulse-echo method was analyzed. For this purpose, reinforced concrete walls were made that contain No. 3, No. 4, or No. 5 steel bars, and expanded polystyrene spheres 50 mm (1.97 in.) in diameter, which represent internal voids. Spheres of smaller diameter were not used because their detection is very low. An ultrasonic pulse-echo device of 50 kHz frequency transverse waves that uses a synthetic aperture focusing technique (SAFT) was used. The steel bars were placed with different separations to observe the effect they cause in a scan. In addition, the spheres were laid between these different configurations with the purpose of verifying if their detection is possible. Additionally, image processing was carried out to eliminate or totally reduce the effect of the steel bars in the scans. This research concluded that when scans are performed on strips with transverse No. 3, No. 4, and No. 5 bars, these would appear in the ultrasound image with a probability of 35.4%, 41.7%, and 62.5%, respectively. In addition, if the scan is performed on a strip with No. 4 or No. 5 bars, which have the same direction of the scan, they appear in large magnitude in the ultrasound images, so it is very difficult to distinguish if there is another material in these areas. However, in this last case, if the bars are No. 3, they do not appear in the scan. On the other hand, the spheres were located with a probability of 81.3% when they were located between steel bars separated by a distance greater than or equal to 100 mm (1.97 in.). [ABSTRACT FROM AUTHOR]

Pulse-echo arrays are used in radar, sonar, seismic, medical and non-destructive evaluation. There is a trend to produce arrays with an ever-increasing number of elements. This trend presents two major challenges: (i) often the size of the elements is reduced resulting in a lower signal-to-noise ratio (SNR) and (ii) the time required to record all of the signals that correspond to every transmit--receive path increases. Coded sequences with good autocorrelation properties can increase the SNR while orthogonal sets can be used to simultaneously acquire all of the signals that correspond to every transmit--receive path. However, a central problem of conventional coded sequences is that they cannot achieve good autocorrelation and orthogonality properties simultaneously due to their length being limited by the location of the closest reflectors. In this paper, a solution to this problem is presented by using coded sequences that have receive intervals. The proposed approach can be more than one order of magnitude faster than conventional methods. In addition, binary excitation and quantization can be employed, which reduces the data throughput by roughly an order of magnitude and allows for higher sampling rates. While this concept is generally applicable to any field, a 16-element system was built to experimentally demonstrate this principle for the first time using a conventional medical ultrasound probe. [ABSTRACT FROM AUTHOR]

We present mathematical modeling of the process of determining the time coordinate of the moment of arrival of a pulse echo in the dual-frequency probing technique, as well as graphs of the involved measurement error versus the comparator's discrimination threshold for different ratios of frequencies and distances and ratio of the frequencies of emitted pulses. Mathematical modeling has revealed limiting cases in which the measurement error increases and can reach 3–4%. Analysis of results has made it possible to identify additional requirements for the mathematical processing of received signals to keep the error within 1%. [ABSTRACT FROM AUTHOR]

Determination of ultrasonic propagation velocity in materials provides an insight into their intrinsic and extrinsic properties. The American National Standard, E-494-95 describes an exhaustive procedure of ultrasonic velocity measurement and various material parameters that are based on ultrasonic velocity. Ultrasonic pulser-receiver is a device, used to excite piezoelectric transducers. Further, a oscilloscope or data acquisition device is employed to display and analyze the receiver output. The quality of measured parameter mainly depends on the capabilities of the measurement device used at the receiver. Careful study of the displayed wave pattern enables the detection of deformities inside the metal blocks. In this article, a low cost pulser-receiver designed in the laboratory has been discussed. The design provided can be used by a person having considerable knowledge of electronics to build up a pulser-receiver. The designed device has been tested for its functionality to measure ultrasonic velocity and attenuation. The measured values have been compared with the literature values and are in close agreement with the measurements taken by an imported system. [ABSTRACT FROM AUTHOR]

This paper presents an opportunity to cancel range ambiguities in synthetic aperture radar (SAR) configuration. One of the limitations of SAR systems is the range ambiguity phenomenon that appears with long delayed echoes. The reflected signal corresponding to one pulse is detected when the radar has already transmitted the next pulse. Thus, this signal is considered as an echo from the next pulse. This paper investigates the opportunity of coding the transmitted pulses using an orthogonal frequency-division multiplexing pulse. The results show that coded-OFDM signals outperform conventional chirp signal and make it possible to relax constraints placed upon the pulse repetition frequency. [ABSTRACT FROM PUBLISHER]

Corrosion of reinforcing steel in concrete is one of the major durability problems faced by civil engineers as they maintain an aging infrastructure. The problem accelerates since steel is embedded inside concrete. If it remains unnoticed inside concrete, it further accelerates and can cause loss of life and property. This article discusses a nonintrusive corrosion monitoring technique for early detection of damages in steel embedded in concrete. Corrosion manifests itself in debond and pitting steel bars. Guided ultrasonic waves offer a potentially attractive solution for this problem. But it is imperative to excite the right mode for detection of a particular type of corrosion. In the present work, longitudinal guided ultrasonic waves have been utilized to monitor notch and debond defects in steel bars in concrete simulating pitting and delamination phenomena caused by corrosion. Two ultrasonic techniques of pulse transmission and pulse echo were used to monitor the healthy and damaged specimens. The developed methodology is successfully applied for real time monitoring of RC beam specimens undergoing accelerated chloride corrosion. The ultrasonic signals effectively relate to the state of reinforcing bars. [ABSTRACT FROM PUBLISHER]

The sterilisation of tinned foods aims to improve the wholesomeness and the bacteriological stability of foods. The Clostridium botulinum, which is a sulphite-reducing anaerobic bacterium is often the choice of a reference bacterium because of its strong resistance to heat treatments typically used for sterilisation. The analysis of tinned foods by a microbiologic method entails the use of sterilised materials and very strict working conditions. Moreover, these analyses are relatively slow and expensive. Negative results obtained on samples subjected to a microbiologic analysis do not imply that the whole sample is relatively free of bacteria to a safe level. In this work, we utilise ultrasonic testing to detect the effects of the sulphite-reducing anaerobic bacteria on the ultrasonic properties of foods. The experiments on the samples take place in a parallelepipedic tank, and the samples are insonified by a short ultrasonic pulse of frequency 10 MHz which is generated and detected by the same transducer in a send-receive geometry. The signal detected by the transducer is amplified, captured on an oscilloscope and is then transmitted to a computer by an IEEE 488 interface. These ultrasonic data is processed in the computer to determine the viscoelastic properties of the samples, which are phase velocity and attenuation. The measured change in these properties as function of time allows us to determine the different phases of the development of C. botulinum bacteria within the sample. The results show also the effect of the bacterial charge on the evolution of different phases. [ABSTRACT FROM AUTHOR]

Degradation in mechanical properties (compression, flexural and ILS) of glass epoxy composite laminates with induced defects (simulating delaminations) was studied. The defects were characterized by using the A-scan ultrasonic pulse-echo technique. The two A-scan parameters, viz. the back wall echo amplitude and time of flight, were followed respectively, as functions of the defect size (diameter) and its location in the laminate thickness. The mechanical properties of laminates were evaluated destructively for different defect sizes and locations. An attempt has been made to express the mechanical properties in terms of the two NDT scan parameters characterizing the defects and empirical equations presented. [ABSTRACT FROM AUTHOR]

In this study, physicomechanical characterization is evaluated using ultrasonic pulse–echo measurements through high-volume fly ash (HVFA) cement paste. The composites were tested at different water-content levels to infer their influence on the pulse–echo measurements. To achieve different water content levels, samples were dried in an oven between 60 and 105°C at 6-, 12-, and 24-h intervals. Physical (dry unit weight, apparent specific gravity, porosity at 7 and 28 days) and mechanical (unconfined compression test at 7 and 28 days) measures were performed.The research indicates that the degree of saturation significantly affects the ultrasonic pulse–echo of HVFA cement paste. The empirical relations of the physical and mechanical properties with ultrasonic pulse velocity are highly correlated. [ABSTRACT FROM AUTHOR]

Ultrasonic is one of the well-known methods for surface roughness measurement, but small roughness will only lead to a subtle variation of transmission or reflection. To explore sensitive techniques for surfaces with small roughness, nonlinear ultrasonic measurement in through-transmission and pulse-echo modes was proposed and studied based on an effective unit-cell finite element (FE) model. Higher harmonic generation in solids was realized by applying the Murnaghan hyperelastic material model. This FE model was verified by comparing the absolute value of the nonlinearity parameter with the analytical solution. Then, random surfaces with different roughness values ranging from 0 μm to 200 μm were repeatedly generated and studied in the two modes. The through-transmission mode is very suitable to measure the surfaces with roughness as small as 3% of the wavelength. The pulse-echo mode is sensitive and effective to measure the surface roughness ranging from 0.78% to 5.47% of the wavelength. This study offers a potential nondestructive testing and monitoring method for the interfaces or inner surfaces of the in-service structures. [ABSTRACT FROM AUTHOR]