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Space charge behavior is important in the oil-immersed-paper insulation in converter transformers for HVDC transmission. This paper reports an investigation of the space charge property in samples with two layers of oil-immersed-paper and oil. Based on pulsed electroacoustic (PEA) technique, a waveform recovery method was proposed to get rid of the effects of interface and anisotropy on PEA result, and the space charge distributions in the two-layer samples under different voltage and oil thicknesses were measured. It?s found that the charges with the same polarity as oil side electrode were accumulated at the interface and gradually increased with the increase of applied voltage. However, the positive charge charges always appeared in the oil under positive and negative voltages. Moreover, the charges in samples increased with the increase of applied voltage, while the amount of interface charges decreased with the increase of oil thickness. Due to the existence of interfacial charges, the electrical field in oil-immersed-paper was distorted with its maximum close to the interface. It is indicated that due to the different mobility properties of charges in paper and oil and the interface trap state, the interface between paper and oil plays an important role in charge formation and decay. [ABSTRACT FROM PUBLISHER]

Objective: Long-term monitoring of epilepsy patients outside of hospital settings is impractical due to the complexity and costs associated with electroencephalogram (EEG) systems. Alternative sensing modalities that can acquire, and automatically interpret signals through easy-to-use wearable devices, are needed to help with at-home management of the disease. In this paper, a novel machine learning algorithm is presented for detecting epileptic seizures using acoustic physiological signals acquired from the neck using a wearable device. Methods: Acoustic signals from an existing database, were processed, to extract their Mel-frequency Cepstral Coefficients (MFCCs) which were used to train RUSBoost classifiers to identify ictal and non-ictal acoustic segments. A postprocessing stage was then applied to the segment classification results to identify seizures episodes. Results: Tested on 667 hours of acoustic data acquired from 15 patients with at least one seizure, the algorithm achieved a detection sensitivity of 88.1% (95% CI: 79%–97%) from a total of 36 seizures, out of which 24 had no motor manifestations, with a FPR of 0.83/h, and a median detection latency of −42 s. Conclusion: The results demonstrated for the first time the ability to identify seizures using acoustic internal body signals acquired on the neck. Significance: The results of this paper validate the feasibility of using internal physiological sounds for seizure detection, which could potentially be of use for the development of novel, wearable, very simple to use, long term monitoring, or seizure detection systems; circumventing the practical limitations of EEG monitoring outside hospital settings, or systems based on sensing modalities that work on convulsive seizures only. [ABSTRACT FROM AUTHOR]

This paper presents a microfabricated nozzleless acoustic droplet ejector with electrically tunable droplet size as a new tool for on-demand picking and placing semiconductor chips for semiconductor packaging. The ejector is based on a 2-mm-thick lead zirconate titanate (PZT) sheet with a planar annular-ring air-cavity acoustic Fresnel lens on top. When driven with sinusoidal pulsed voltage signals of 1.16 MHz, the ejector generates focused ultrasound with 1-mm focal diameter and 5-mm focal depth at 22 mm focal length in sodium polytungstate (SPT) solution. A finite-element-method (FEM) simulation model calculating the acoustic-field-induced fluid motion during the droplet ejection process has been developed, and verified by experiments, in which the device ejects SPT droplets whose diameter is from 850 to 2, 490 μm, controlled by the driving pulse width and voltage. The ejected droplets are able to carry 400-μm-thick square silicon chips with side length from 700 to 3, 100 μm. A polyester channel-embedded guiding cover for semi-automatic loading of silicon chips to the ejection site is designed to avoid manual placement of the silicon chips. With the proof-of-concept system, we demonstrate ejecting silicon chips out of SPT surface onto a nearby paper, assembling them into arrays with good repeatability. [2020-0337] [ABSTRACT FROM AUTHOR]

Acoustic images are an emergent data modality for multimodal scene understanding. Such images have the peculiarity of distinguishing the spectral signature of the sound coming from different directions in space, thus providing a richer information as compared to that derived from single or binaural microphones. However, acoustic images are typically generated by cumbersome and costly microphone arrays which are not as widespread as ordinary microphones. This paper shows that it is still possible to generate acoustic images from off-the-shelf cameras equipped with only a single microphone and how they can be exploited for audio-visual scene understanding. We propose three architectures inspired by Variational Autoencoder, U-Net and adversarial models, and we assess their advantages and drawbacks. Such models are trained to generate spatialized audio by conditioning them to the associated video sequence and its corresponding monaural audio track. Our models are trained using the data collected by a microphone array as ground truth. Thus they learn to mimic the output of an array of microphones in the very same conditions. We assess the quality of the generated acoustic images considering standard generation metrics and different downstream tasks (classification, cross-modal retrieval and sound localization). We also evaluate our proposed models by considering multimodal datasets containing acoustic images, as well as datasets containing just monaural audio signals and RGB video frames. In all of the addressed downstream tasks we obtain notable performances using the generated acoustic data, when compared to the state of the art and to the results obtained using real acoustic images as input. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel communication framework, Acoustic-WiFi, that utilizes the acoustic channel (i.e., microphone/speaker) as a control channel to develop more efficient Wi-Fi networks. We used the Acoustic-WiFi framework to develop a Power Saving Mode (PSM) scheme; A2PSM, and a smart contention resolution scheme; Harmony. In A2PSM, we propose an acoustic channel assisted power saving scheme for the Wi-Fi interface, which addresses the inefficiency of the existing power saving schemes in smart devices. In this scheme, we leverage the low power consumption of the acoustic interfaces to reduce the wakeup events of the Wi-Fi interface when it is in power saving mode. We develop a small-scale prototype testbed on real smartphones to evaluate the proposed A2PSM scheme. Experiments show that A2PSM could save up to more than 25% more power than the existing schemes. In Harmony, we address the overhead of the Wi-Fi backoff scheme (i.e., contention window countdown, DIFS) and reduce the overall collisions among the devices. Harmony uses the acoustic channel for contention resolution in Wi-Fi networks. We also evaluate Harmony using real testbed and simulation. Experiments using the testbed show a 40% gain in throughput over the 802.11 Wi-Fi backoff scheme, while simulation results show a gain of more than 27% for dense networks. [ABSTRACT FROM AUTHOR]

Free metallic particles are the main factor inducing flashover incidents and threatening the safety of gas-insulated switchgear (GIS) and gas-insulated transmission line (GIL) devices. Acoustic diagnosis is widely used to detect free metal particles due to its high sensitivity, but it generally fails under multiple particle conditions because of the overlap of acoustic signals. This paper proposes a new method of acoustically recognizing multiple free metallic particles. The pattern of Δt-Normalized N that can be used to distinguish single/multi-particles is determined first. Second, each particle's neighboring collision signals are extracted from raw data by the established physical relation between adjacent collision signals. Wire, lamellar, and spherical free metal double-particles’ mass values are calculated as per the numerical connection between adjacent collision signals. The geometry of the particles is assumed to be known, so the density of the spherical particles can be effectively estimated. The proposed method is validated in a scale concentric hemisphere platform. The results of this work may provide a workable reference for GIS free metal multi-particle monitoring. [ABSTRACT FROM AUTHOR]

The Ultra-short baseline (USBL) positioning system has important application in the positioning of underwater vehicles. The installation error angle of the USBL positioning system has an important influence on the positioning accuracy of USBL system. The traditional calibration methods have limited estimation accuracy for installation error angles and have high route requirements. To solve the above problems, a calibration method of installation error angle based on attitude determination is proposed in this paper. When strapdown inertial navigation system (SINS) and USBL are fixed together in the application process, the installation error angle of USBL is fixed and unchanged. Then the calibration of installation error angle can be accomplished with the idea of attitude determination. The vector observation model based on the installation error angle matrix is established first. Observation vectors are obtained by the relative position of transponders in the USBL coordinate frame. The reference vector is calculated by position of transponder, position and attitude of SINS and lever arm between SINS and USBL. By constructing the observation vectors and the reference vectors, the proposed method can calibrate the installation error angle of SINS and USBL in real time. The advantages of the proposed method are that it has no specific requirements for the calibration route and can calibrate the installation error angle in real time with high accuracy. In order to verify the performance of the proposed algorithm, simulation experiment and field experiment are carried out in this paper. The results of simulation experiment and field experiment show that the proposed method can give the estimated installation error angle of USBL in real time, and the estimated result is the best among several methods. The proposed method can not only achieve the calibration of the installation error angle in circular trajectory, but also in straight trajectory. [ABSTRACT FROM AUTHOR]

This paper investigates a feasible nondestructive method for micron-sized kissing defects in the composite insulators, which are commonly utilized in ultra-high voltage (UHV) power grid. In this paper, cylindrical adhesive contact model was established to describe the obvious distortion of ultrasound propagation caused by kissing defects on the polymeric interface of composite insulators. The ultrasonic nonlinearity parameter was measured for each of the kissing defective and intact specimens. Moreover, the theoretical analysis has been proved by the test results on the kissing defective samples, which indicates that the 0.7 μm kissing defects existed in the composite insulators could be successfully recognized by the nonlinear ultrasonic methods and the nonlinearity is reduced by interface roughness. [ABSTRACT FROM AUTHOR]

In the field of ultrasonic array imaging for non-destructive testing (NDT), material structural noise caused by grain scattering is one of the main sources of error when characterizing defects that are found in the polycrystalline materials. The existence of grains can also severely affect the detection performance of ultrasonic testing, making small defects indistinguishable from the grain indications due to ultrasonic attenuation and backscatter. This paper proposes a model in which the statistical distribution of the defect data is obtained from different realizations of the grain structure. This statistical distribution, termed the defect+grains model in this paper, is shown to contain information that is needed for detection and characterization of defects. Hence, given a specific measurement configuration, the characterization result can be obtained by constructing a defect+grains model based on the multiple realizations of each possible defect and calculating their probability. The detection, classification, and sizing accuracy are shown to be predictable by quantifying the probabilities that an experimentally measured defect matches the different defect+grains models. This defect+grains modeling approach gives insight into the detection/characterization problem, leading to an evaluation of the fundamental limits of the achievable inspection performance. [ABSTRACT FROM AUTHOR]

Time-of-flight (TOF) measures are valuable in the estimation of displacements, distances, and moving fluids’ speed, e.g., the wind. Of the different types of methods that measure wind speed, the ultrasound is highlighted. As part of the calculation required to acquire the wind speed, one must find the time that an ultrasonic wave takes to travel from one particular place to another. This time is known as TOF. The biggest challenge in measuring TOF is to determine the correct moment when the ultrasonic wave arrived at the reception because it will be immersed in noise and its envelope probably will be corrupted by the actions of the wind. The methodology proposed by this paper presents a combined algorithm between an extended Kalman Filter (EKF) and a zero-crossing detector (ZCD) technique. The EKF method is responsible for the noise elimination stage and estimation of the real ultrasound’s envelope, while the ZCD detects the correct TOF of the estimated signal. This paper also presents the flaws and solutions found for each technique. It was shown that for speeds up to 75 km/h, the coefficient that was found to be $R^{2}\,\,=0.99977$. [ABSTRACT FROM AUTHOR]

Ultrasound therapy has a long history of novel applications in medicine. Compared to high-intensity ultrasound used for tissue heating, low-intensity ultrasound has drawn increasing attention recently due to its ability to induce therapeutic changes without biologically significant temperature increase. Low-intensity pulsed ultrasound (LIPUS) is a specific type of ultrasound that delivers at a low intensity and outputs in the mode of pulsed waves. It has minimal thermal effects while maintaining the transmission of acoustic energy to the target tissue, which is able to provide noninvasive physical stimulation for therapeutic applications. LIPUS has been demonstrated to accelerate the healing of fresh fracture, nonunion and delayed union in both animal and clinical studies. The effectiveness of LIPUS for the applications of soft-tissue regeneration and inhibiting inflammatory responses has also been investigated experimentally. Additionally, research has shown that LIPUS is a promising modality for neuromodulation. The purpose of this review is to provide an overview of the recent developments of LIPUS for therapeutic applications, based on the papers that report positive effects, and to present the findings on the understanding of its mechanism. Current available LIPUS devices are also briefly described in this paper. [ABSTRACT FROM AUTHOR]

The fabrication of piezoelectric ZnO-based micro-electro-mechanical systems (MEMS) acoustic sensor has been reported. The sensor structure consists of a piezoelectric ZnO film deposited between two Al electrodes on a thin silicon diaphragm. A microtunnel is fabricated in the sensor structure using novel approach. This microtunnel is used to protect the diaphragm and determine the lower cut-off frequency of device. The approach presented in this paper completely removed a serious problem of microtunnel blockages during fabrication of sensors. In the developed process, the acoustic sensor fabricated using silicon-on-insulator and the Pyrex glass wafers are diced separately with same chip dimensions. Finally, both Pyrex glass and acoustic sensor chips are fitted in a jig for alignment and then anodically bonded. In reference to microtunnel blockages, the yield of the present technique is obtained as almost 100%. Also, the technique will serve as a cost-effective alternative to the present practice. The developed technique can also be used in manufacturing of similar devices where the microtunnels or microchannels are required in device structure. The technological development is supported by extensive atomic force microscopy (AFM), field emission scanning electron microscopy, Raman spectroscopy, and X-ray diffraction studies of ZnO film; glass-to-silicon bond strength measurement; resonance frequency measurement by laser doppler vibrometer; response characterization of the fabricated sensor, and scanning electron microscopy of microtunnel mouth to demonstrate the feasibility and yield of the process. [ABSTRACT FROM AUTHOR]

Automatically synthesizing sounds for different visual contents poses a challenge and there is a strong need to facilitate the direct creation of realistic sounds. Different from previous works, in this paper, we propose a novel deep learning based approach, which formulates sound simulation as a regression problem. This allows us to circumvent the complexity of the acoustic theory by a novel, general-purpose neural sound synthesis (V2RA) network. Moreover, the end-to-end architecture of V2RA ensures full training without any extra inputs, which thereby greatly improves the scalability and reusability over previous works. In contrast to conventional visual-to-audio generation methods, the V2RA problem is established and solved by generative adversarial networks (GANs). Furthermore, our network architecture can directly predict synchronized raw audio signals (unlike most existing approaches that handle the audio through spectrograms) and generate sound in real time. To evaluate the performance of the neural network generator, we specifically introduce two quantitative scores. Various experiments demonstrate that our V2RA network can produce compelling sound results, which thus provides a viable solution for applications such as sound design and dubbing. [ABSTRACT FROM AUTHOR]

Quantitative assessment of myocardial stiffness is crucial to understand and evaluate cardiac biomechanics and function. Despite the recent progresses of ultrasonic shear wave elastography, quantitative evaluation of myocardial stiffness still remains a challenge because of strong elastic anisotropy. In this paper we introduce a smart ultrasound approach for non-invasive real-time quantification of shear wave velocity (SWV) and elastic fractional anisotropy (FA) in locally transverse isotropic elastic medium such as the myocardium. The approach relies on a simultaneous multidirectional evaluation of the SWV without a prior knowledge of the fiber orientation. We demonstrated that it can quantify accurately SWV in the range of 1.5 to 6 m/s in transverse isotropic medium (FA < 0.7) using numerical simulations. Experimental validation was performed on calibrated phantoms and anisotropic ex vivo tissues. A mean absolute error of 0.22 m/s was found when compared to gold standard measurements. Finally, in vivo feasibility of myocardial anisotropic stiffness assessment was evaluated in four healthy volunteers on the antero-septo basal segment and on anterior free wall of the right ventricle (RV) in end-diastole. A mean longitudinal SWV of 1.08 ± 0.20 m/s was measured on the RV wall and 1.74 ± 0.51 m/s on the septal wall with a good intra-volunteer reproducibility (±0.18 m/s). This approach has the potential to become a clinical tool for the quantitative evaluation of myocardial stiffness and diastolic function. [ABSTRACT FROM AUTHOR]

This paper presents a dual-frequency piezoelectric micromachined ultrasonic transducer (pMUT) array based on thin ceramic PZT for endoscopic photoacoustic imaging (PAI) applications. With a chip size of $7\times {7}$ mm2, the pMUT array consists of 256 elements, half of which have a lower resonant frequency of 1.2 MHz and the other half have a higher resonant frequency of 3.4 MHz. Ceramic PZT, with outstanding piezoelectric coefficients, has been successfully thinned down to a thickness of only $4~\mu \text{m}$ by using wafer bonding and chemical mechanical polishing (CMP) techniques and employed as the piezoelectric layer of the pMUT elements. The diaphragm diameters of the lower-frequency and higher-frequency elements are $220~\mu \text{m}$ and $120~\mu \text{m}$ , respectively. The design methodology, multiphysics modeling, fabrication process, and characterization of the pMUTs are presented in detail. The fabricated pMUT array has been fully characterized via electrical, mechanical, and acoustic measurements. The measured maximum responsivities of the lower- and higher- frequency elements reach 110 nm/V and 30 nm/V at their respective resonances. The measured cross-couplings of the lower-frequency elements and higher-frequency elements are about 9% and 5%, respectively. Furthermore, PAI experiments with pencil leads embedded into an agar phantom have been conducted, which clearly shows the advantages of using dual-frequency pMUT arrays to provide comprehensive photoacoustic images with high spatial resolution and large signal-to-noise ratio simultaneously. [2021-0114] [ABSTRACT FROM AUTHOR]

In this correspondence paper, we address the direct position determination (DPD) problem for wideband stationary sources using time-delayed and Doppler-stretched signals collected by multiple moving receivers. The source signals are assumed to be zero-mean, stationary, and Gaussian distributed, which is reasonable in most passive sonar and acoustics scenarios. A scaled formulation is used for wideband signals to elaborate the Doppler effect, as significant biases will be introduced if such signals are approximated with narrowband models directly. In this paper, wideband signals are decomposed into a small number of low-dimensional components with high accuracy, and a computationally efficient DPD method is proposed by jointly utilizing the time delay and scaling information of received signals. In order to evaluate the performance of the proposed DPD method, the Cramér Rao lower bound for source localization in the considered scenario is derived. Numerical results validate the approximation of wideband signals and demonstrate the performance of the proposed method. [ABSTRACT FROM AUTHOR]

Partial discharge (PD) is the main sign of the insulation deterioration; therefore, the online PD localization of the power transformers can provide the equipment degradation characteristics and has great value for the power grid. Because of some unique merits, acoustic PD detection is one of the best options for such applications. However, when discharges happen inside the windings, precise PD localization by acoustic method becomes very challenging. As the acoustic PD signal can be reverberated and distorted along its propagation, the type and number of sensors, with their installation, should be carefully studied and selected. In this paper, the acoustic wave propagation inside the transformer is explored via numerical simulation. Based on the understanding of wave propagation, a novel-structure fiber-optic acoustic sensor array is properly designed and installed into one phase winding, which is from a real 35 kV transformer. Experimental verification shows that, by using this proposed design, PD localization with less than 5-cm error can be achieved. Therefore, the novel sensor array developed in this paper, together with the installation and localization method, unveils a novel access to accurate online PD localization, especially for those PDs which happen inside transformer windings. [ABSTRACT FROM AUTHOR]

This paper presents an analytical approach for the implementation of high quality-factor ($Q$) resonators with arbitrary cross-sectional vibration mode shapes in anisotropic single-crystal substrates. A closed-form dispersion relation is analytically derived to characterize the dynamics of guided waves in rectangular waveguides. Three categories of waves with propagating, standing-evanescent, and propagating-evanescent dynamics are identified and used for energy localization of acoustic excitations with arbitrary cross-sectional vibration patterns. An analytical design procedure is presented for dispersion engineering of waveguides to realize high- $Q$ resonators without the need for geometrical suspension through narrow tethers or rigid anchors. The effectiveness of the dispersion engineering methodology is verified through the development of experimental test vehicles in 20- $\mu \text{m}$ -thick single-crystal silicon substrate with 500-nm aluminum nitride transducers. Various proof-of-concept resonators, representing guided waves with different dispersion types, are presented and compared to highlight the optimum design procedures for $Q$ enhancement and spurious mode suppression. Part I of this paper presents the operation principle of guided-wave resonators based on the analytical derivation of dispersion relation followed by a systematic resonator design procedure. Numerical and experimental characterizations for verification of the proposed design procedure and extensive measurement data on proof-of-concept resonators are presented in Part II. [ABSTRACT FROM AUTHOR]

This paper investigates the use of an acoustic glider to perform acoustical meteorology. This discipline consists of analyzing ocean ambient noise to infer above-surface meteorological conditions. The paper focuses on wind speed estimation, in a near-shore marine environment. In such a shallow water context, the ambient noise field is complex, with site-dependent factors and a variety of nonweather concurrent acoustic sources. A conversion relationship between sound pressure level and wind speed is proposed, taking the form of an outlier-robust nonlinear regression model learned with in situ data. This method is successfully applied to experimental data collected in Massachusetts Bay (MA, USA) during four glider surveys. An average error in wind speed estimation of 1.3 m · s−1 (i.e., average relative error of 14%) over wind speed values up to 17 m · s−1 is reported with this method, which outperformed results obtained with relationships from the literature. Quantitative results are also detailed on the dependence of wind speed error estimation on the environment characteristics, and on the classification performance of observations contaminated by acoustic sources other than wind. Passive acoustic-based weather systems are a promising solution to provide long-term in situ weather data with fine time and spatial resolutions. These data are crucial for satellite calibration and assimilation in meteorological models. From a broader perspective, this paper is the first step toward an operationalization of acoustic weather systems and their on-board embedding in underwater monitoring platforms such as gliders. [ABSTRACT FROM AUTHOR]

This paper introduces a computationally intensive method for measuring distance at high measurement rates using chaotic pulse-position (CPPM) signals and single-bit signal processing in a single ultrasound sensor system. To prevent crosstalk from other ultrasonic sensor systems, a chaotic system is used, and the ultrasonic pulses are transmitted as a pulse sequence generated by CPPM. After receiving the ultrasound signal, the single-bit signal was generated by a fast Fourier transform threshold, which also functions as an environmental noise filter. Single-bit signal processing has been adopted to reduce the computational load when cross correlating the transmitted and received signals for time-of-flight calculations. Single-bit signal processing has more than 100 times memory saving effect in this paper. Additionally, as the signal-to-noise ratio increases, extension of the maximum measurable distance in the ultrasonic distance sensor system is expected. The simulation shows the crosstalk rejection performance of the proposed method, and the experimental results confirm the improvement of the measurement speed by the proposed method. [ABSTRACT FROM AUTHOR]

Nowadays, the importance of the blood particles separation is undeniable in medical fields and there are different sorts of separation methods accordingly. Acoustic cell separation is chosen in this paper. Also, numerical methods have been used to study the effect of geometrical factors on the separation of the particles before spending time and expenses in a trial and error manner experimentally. We have implemented a plenary finite-element-based simulation of separating blood particles such as white blood cells and platelets in an acoustic field using standing surface acoustic waves. In this paper, unlike previous works in which the channel is rectangular; the channel is trapezoidal in order to make the separation more efficient. By changing the trapezoidal leg angle, WBC’s distance from the midline will be different. The designed device is a bio-MEMS channel containing two inlets which are for the sheath flow and for the blood particles, a trapezoidal main channel, and three outlets. Two aluminum interdigital transducers are located on the LiNbO3 substrate. For creating the acoustic force, we have applied an alternating voltage to transducers. Blood particles will be moved toward the acoustic nodes because of the positive acoustic contrast factor. Since acoustic radiation force depends on the size of the particles and their compressibility, cells can be sorted according to their diameter and compressibility; hence, particles will be separated. For optimizing the device, we have changed the trapezoidal channel angle, the input voltage, and the flow rate. [ABSTRACT FROM AUTHOR]

The 21st century is defined as the era of technological development. With drastic increase in population, automation is becoming the need of the hour in order to make life more comfortable and easy. Due to the advancement and development in the field of automation and embedded system, the notion of smart car has become very popular. Smart cars are modernizing trends in the traditional automobile industry. Companies across the globe have been investing a huge amount of resources on the production and design of smart cars. Every technological development needs to overcome certain obstacles, and hence, in this paper, a design of a collision detection system for smart car using light fidelity (Li-Fi) and ultrasonic sensor on the Arduino platform is proposed. This design consists of an ultrasonic sensor, an Arduino processor, and a Li-Fi circuit. The ultrasonic is used for measurement of distance between vehicles, and Arduino processes the data and makes decisions accordingly. Data transmission between vehicles is ensued using a Li-Fi transmitter circuit and a Li-Fi receiver circuit. The transmitter circuit is mounted on the tail lights of the leading car and the receiver circuit is mounted on the front side of the car that follows. Using visible light communication, the transmitter circuit transmits the calculated speed and the information is received by the receiver circuit of the second car. On the basis of the information received, the speed of the second car is changed in order to avoid collision. In this paper, a system that can detect and thus avoid collision between vehicles and prevent accidents is proposed and studied. [ABSTRACT FROM AUTHOR]

Underwater object detection and tracking are of considerable interest in offshore defense. Recently, a new method that takes advantage of direct-current resistivity survey techniques has been introduced as a complement to the conventional detection method for use in acoustically noisy conditions. However, dedicated rapid target localization methods are required to enable real-time tracking in this detection method. Therefore, in this paper, we propose a real-time localization method using grid-based template matching. The main features of our method are as follows: 1) measurement data sets from two separate detection lines are used; 2) template matching based on correlation is used; 3) the templates are precalculated by numerical modeling; and 4) real-time localization processing is implemented by efficient calculations. To verify our method, we first performed experiments for stationary target object positions under a water tank condition: template versus numerical modeling data and template versus physical modeling data. Next, real-time localization experiments for a moving target in the water tank were conducted using the real-time data at 3-Hz refresh rate. In the real-time experiments, we confirmed that the estimated positions could keep track of the actual target positions continuously. We expect that this paper will contribute positively to offshore defense and surveillance. [ABSTRACT FROM AUTHOR]

In contactless energy transfer and vibration system (CETVS) for rotary ultrasonic machining, the energy is delivered to an ultrasonic transducer equipped with a rotary spindle shank through a loosely coupled transformer (LCT). The purpose of this paper is to present a simplified construct, referred to as self-compensation system, to overcome the drawbacks of external compensation elements occupying the limited shank space during the LCT's leakage inductance compensating and the transducer's capacitance compensating. The advantage of this approach is that the secondary leakage inductive reactance of the LCT and the capacitive reactance of the transducer are mutually compensated without an intermediate element, which conserves the spindle shank space and reduces the operating load of an LCT. In this paper, we first derive the mutual compensation equation between a transducer and an LCT. Then, for a given transducer, the structural parameters of an LCT are designed with theoretical calculations and simulation analysis. Experiments are conducted with the self-compensation system excited by a 50 V ultrasonic signal. The results show that the energy transfer efficiency of LCT reached 92.0%, the amplitude of the transducer reached $10.7\,\mu {\rm{m}}$ , when the CETVS is self-compensated. These results indicate that this self-compensation theory and design are feasible. [ABSTRACT FROM AUTHOR]

Considerable research efforts have been expended in investigating and optimising the emission of acoustic pressure impulses by high power spark discharges in water. Several methods are typically used to generate transient underwater spark discharges, including breakdown of water by stressing electrode(s) with HV impulses, initiation of spark discharges with thin metallic wires placed between opposite electrodes and by injecting gas bubbles into the inter-electrode gap. This paper is aimed at the investigation of the acoustic, hydrodynamic and electrical characteristics of underwater spark discharges initiated by injected air-bubbles. At a constant applied voltage, the injection of air bubbles allows the inter-electrode gap to be increased thus producing stronger acoustic impulses. This paper reports on the impact of injected air bubbles on the characteristics of transient underwater plasma discharges and on the functional relationships between hydrodynamic and electrical parameters of such discharges, including breakdown voltage, plasma resistance, energy delivered into the plasma cavity and the period of gas/plasma cavity oscillation. An analytical model which relates the acoustic efficiency, plasma resistance and energy available in discharge has been developed which can be used for the optimisation and tailoring of underwater plasma-acoustic sources. [ABSTRACT FROM AUTHOR]

In this paper, we propose a non-contact ultrasonic liquid flowmeter based on AlN piezoelectric micromachined ultrasonic transducer (PMUT) arrays. Two 10 by 10 PMUT arrays with resonant frequency of 980 kHz in air are mounted outside of a pipe to measure liquid flow without contacting the liquid. An acoustic matching layer is designed to mitigate the loss of sound waves caused by sound reflection. Under excitation of continuous wave, the flow of the liquid can be determined via detecting the phase difference between transmitting and received signals. The measurement range of flow is 0.515 L/min ~ 3.40 L/min and the measurement error is less than 3%. Moreover, an interpolation method is proposed to reduce the signal sampling frequency without obviously affecting the measurement accuracy, which shows potential for further system integration. [2021-0033] [ABSTRACT FROM AUTHOR]

This paper presents an airborne piezoelectric micromachined ultrasonic transducers (PMUTs) operated at low frequency (40–50 kHz) for long-range detection, where the acoustic absorption loss in air is relatively low (0.8–1 dB/m). The PMUTs made with single-crystal Lead Zirconate Titanate (PZT) enables a high piezoelectric coefficient (${e} _{31, f} \approx ~16$ - 24 C/ $\text{m}^{{2}}$), and a low dielectric constant ($\varepsilon _{\mathrm {r}}~\approx ~308$), achieving high PMUT transceiver efficiency. The $2\times 2$ PMUT array achieves a very high sound pressure level (SPL) output of 109.4 dB at 26 cm distance. Different from conventional PZT PMUTs, this study utilized single-crystal PZT with a low permittivity to achieve a good acoustic reception, demonstrating the sensitivity of 2 mV/Pa. This work reports the PMUT design, modeling, fabrication, characterization, enabling a long-range detection of 4.8 meters in a pulse-echo experiment, which was conducted by a pair of $2\times 2$ PMUT arrays with the matched resonances. [2020-0270] [ABSTRACT FROM AUTHOR]

This paper reviews the main features of acoustic emission technique. First, the characteristics of acoustic signals and their physics are addressed. Then, the structure of acoustic sensors employed for capturing signals is studied. In the next step, the acoustic method of PD measurement is compared with the standard electrical method. Afterward, the applications of AET in PD measurement in different equipment are summarized. All acoustic method and combined acoustic-electrical method for PD localization in transformers are discussed. Moreover, the applications of AET in the monitoring of GIS systems are explained, along with the acoustic behaviors of moving particles in these systems. Finally, the general considerations in the signal processing of the acoustic signals are reviewed. [ABSTRACT FROM AUTHOR]

This paper derives theoretical solutions for three radially layered piezoceramic/epoxy cylindrical composite transducers, which are composed of a solid epoxy disk, two axially polarized piezoceramic rings, and two epoxy rings. Two piezoceramic rings are the functional components, which can actuate and adjust the composite’s performance. According to different functions, three typical transducers are developed. The first one involves both of the two piezoceramic rings acting as actuating elements with parallel connections electrically. The other two involve only one piezoceramic ring as an actuating element, while the other ring that is connected to a resistor acts as a sensing element to adjust the electromechanical characteristics. Based on the plane stress assumption, theoretical solutions of these three transducers in radial vibration are derived, and performance differences of their electromechanical characteristics are analyzed and discussed. Furthermore, the solutions are validated by comparing with the ANSYS simulation results and the experimental data. The simulated and the measured first resonance and antiresonance frequencies are in a good agreement with the theoretical results, which validates the accuracy of the directed solution. This paper contributes to a comprehensive understanding of the proposed cylindrical composite’s electromechanical performance, which is helpful for further application in underwater sound and ultrasonic fields. [ABSTRACT FROM AUTHOR]

In this paper, we assess the importance of microbubble shell composition for contrast-enhanced imaging sequences commonly used on clinical scanners. While the gas core dynamics are primarily responsible for the nonlinear harmonic response of microbubbles at diagnostic pressures, it is now understood that the shell rheology plays a dominant role in the nonlinear response of microbubbles subjected to low acoustic pressures. Of particular interest here, acoustic pressures of tens of kilopascal can cause a reversible phase transition of the phospholipid coatings from a stiff elastic organized state to a less stiff disorganized buckled state. Such a transition from elastic to buckled shell induces a steep variation of the shell elasticity, which alters the microbubble acoustic scattering properties. We demonstrate in this paper that this mechanism plays a dominant role in contrast pulse sequences that modulate the amplitude of the insonifying pulse pressure. The contrast-to-tissue ratio (CTR) for amplitude modulation (AM), pulse inversion (PI), and amplitude modulation pulse inversion (AMPI) is measured in vitro for Definity, Sonazoid, both lipid-encapsulted microbubbles, and the albumin-coated Optison. It is found that pulse sequences using AM significantly enhanced the nonlinear response of all studied microbubbles compared to PI (up to 15 dB more) when low insonation pressures under 200 kPa were used. Further investigation reveals that the origin of the hyperechoicity is a small phase lag occurring between the echoes from the full-and half-amplitude driving pulses, and that the effect could be attributed to the shell softening dynamics of lipid and albumin coatings. We assess that this additional phase in microbubble ultrasound scattering can have a dominant role in the CTR achieved in contrast sequences using AM. We also show that the pressure dependent phase lag is a specific marker for microbubbles with no equivalent in tissue, which can be used to segment microbubbles from the tissue harmonics and significantly increase the CTR. [ABSTRACT FROM AUTHOR]

Several thermal management applications involve fan-mounted heat sinks that result in fan-generated noise as an undesired by-product. These applications require noise reduction and attempt to reduce noise using separate muffler devices. However, space for separate heat-sinking and noise-reducing functionalities may be challenging in high-performance applications such as electronics cooling, data centers, automotive, aviation, and various others. A first-principles-based approach for combined heat sinking and noise reduction in the same functional volume is discussed in this paper. This paper reports on thermal-acoustic co-design of 3-D periodic porous foam structures. In order to enable a design strategy, an analytical framework that characterizes the governing performance indicators of both acoustic and thermo-fluid design on a unifying platform is laid out. A combination of analytical and phenomenological models is used to predict the absorption coefficient, transmission loss (TL), and other acoustic performance indicators. For thermal predictions, an experimentally validated semiempirical model is presented to estimate thermal resistance and static pressure drop of foam heat sink as a function of geometrical parameters as well as flow rates. Octave-band weighted values of acoustic indicators are then compared against thermal indicators to investigate thermal-acoustic co-design aspects. As hydraulic pore radius of porous foam decreases, the acoustic absorption coefficient increases reaching local maxima. Concomitantly, the pore radius decrease not only increases the absorption coefficient while dissipating heat, but also increases the heat sink pressure drop. For a chosen sound absorption region of interest, there exists a particular static pressure drop that maximizes heat sink dissipation for a given radius. The paper concludes by reporting TL and heat sink thermal performance for a generic electronics cooling configuration while elucidating the nuances of the proposed heat sink design using a thermal-acoustic index. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to make a nanofluid/ultrasonic atomization minimum quality lubrication (MQL) system, and to explore the effectiveness of the system used in the grinding process of SKD11 mold steel with heat treatment. Besides, a set of optimized multiple quality characteristics of grinding parameter combinations is obtained by using the Taguchi method and the fuzzy inference system. The experimental parameter combinations design is performed by using $L_{18}(2^{1}\times 3^{7})$ orthogonal table of the Taguchi method, where the experimental parameters are the type of nanoparticles, nanofluid concentration, tangential velocity, table rate, nozzle angle, nozzle distance, air pressure, and spray volume. The single-quality characteristics such as grinding force ratio, grinding temperature, and surface roughness are considered in this paper. The gray relation analysis and the fuzzy inference system are adopted to obtain the multiple performance characteristic index (MPCI), then the combination of maximum MPCI is the optimized multiple quality characteristics of grinding parameter combinations. This paper also compares the difference of nanofluid/ultrasonic atomization MQL and nanofluid/air MQL through the optimized multiple quality characteristics of grinding parameter combinations. Experimental results indicate that the nanofluid parameters containing the type of nanoparticles, nanofluid concentration, and spray volume are the most influential control factors. Comparing nanofluid/ultrasonic atomization MQL with nanofluid/air MQL can also get the best of grinding force ratio, grinding temperature, surface roughness, and surface morphology. Note to Practitioners—The study finds the optimal process parameters for the grinding of hardened mold steel in a nanofluid/ultrasonic atomization minimum quantity lubrication system. At present, grinding hardened mold steel is a costly and time-consuming undertaking, because it lacks an efficient lubricating method. The study considered grinding force ratio, grinding temperature, and surface roughness as single-quality characteristics for gray relational analysis and fuzzy inference to calculate multiple performance characteristic indexes. These indexes identified the optimal parameter combination for grinding hardened mold steel. The results suggested that the proposed lubrication system is highly effective in this regard. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of a novel vibration amplitude control and resonant frequency tracking for piezoelectric transducers (PTs) and ultrasonic motors (USMs). It is based on a generalization of the vector control method to the PT and the USM, which is explained in the first part. We show that two independent controllers with a similar structure are required: one tracks the resonant frequency and the second controls the amplitude. We then present the implementation into a low-cost digital signal processing controller with a sampling period of 200  $\mu$s. Experimental results on a Langevin transducer achieved a time response of 20 ms approximately, and the generality of the method is further demonstrated on a 2-D tactile stimulator at the end of this paper. [ABSTRACT FROM PUBLISHER]

This paper proposes a control framework based on auditory perception. Generally, in robot audition, the motion control of a robot from the sense of hearing relies on sound source localization. We propose in this paper an alternative approach, aural servo, which is derived from the sensor-based control framework. In this approach, robot motions are directly connected to the aural perception: The variation of low-level auditory features dictates the motions applied to the robot through a feedback loop. It has the advantage of being robust to spurious measurements and modeling approximations for a low computational cost. This paper presents the theoretical concept of the aural servo framework. Besides a theoretical analysis, the aural servo framework is validated through several experiments on different robotic platforms and under real-world conditions. [ABSTRACT FROM AUTHOR]

Nonlinear ultrasonic diffuse energy imaging is a highly sensitive method for the measurement of elastic nonlinearity. While the underlying principles that govern the technique are understood, the precise behavior and sensitivity have not previously been quantified. This paper presents experimental, theoretical, and numerical modeling studies undertaken to characterize nonlinear diffuse energy imaging. The influence of incoherent noise, elastic nonlinearity, and instrumentation error are quantified. This paper enables the prediction of spatial sensitivity, aperture, and amplitude dependence of the measurement, all of which moves the technique toward industrial viability. Furthermore, while previous studies have focused on the detection of closed cracks, the ultimate aim for nonlinear ultrasonic imaging in application to material testing is the detection of damage precursors, which requires a sensitivity to weak classical nonlinearity. This paper identifies the experimental requirements necessary for this to be achieved, greatly expanding the potential applicability of nonlinear ultrasonic array imaging. [ABSTRACT FROM AUTHOR]

In this paper, a novel processing framework is introduced for Fourier-domain beamforming of plane-wave ultrasound data, which incorporates coherent compounding and angular weighting in the Fourier domain. Angular weighting implies spectral weighting by a 2-D steering-angle-dependent filtering template. The design of this filter is also optimized as part of this paper. Two widely used Fourier-domain plane-wave ultrasound beamforming methods, i.e., Lu’s f-k and Stolt’s f-k methods, were integrated in the framework. To enable coherent compounding in Fourier domain for the Stolt’s f-k method, the original Stolt’s f-k method was modified to achieve alignment of the spectra for different steering angles in k-space. The performance of the framework was compared for both methods with and without angular weighting using experimentally obtained data sets (phantom and in vivo), and data sets (phantom) provided by the IEEE IUS 2016 plane-wave beamforming challenge. The addition of angular weighting enhanced the image contrast while preserving image resolution. This resulted in images of equal quality as those obtained by conventionally used delay-and-sum (DAS) beamforming with apodization and coherent compounding. Given the lower computational load of the proposed framework compared to DAS, to our knowledge it can, therefore, be concluded that it outperforms commonly used beamforming methods such as Stolt’s f-k, Lu’s f-k, and DAS. [ABSTRACT FROM AUTHOR]

This paper presents the development of a novel acoustic transformer with high galvanic isolation dedicated to power switch triggering. The transformer is based on two capacitive micromachined ultrasonic transducers layered on each side of a silicon substrate; one is the primary circuit, and the other is the secondary circuit. The thickness mode resonance of the substrate is leveraged to transmit the triggering signal. The fabrication and characterization of an initial prototype is presented in this paper. All experimental results are discussed, from the electrical impedance measurements to the power efficiency measurements, for different electrical load conditions. A comparison with a specifically developed finite-element method model is done. Simulations are finally used to identify the optimization rules of this initial prototype. It is shown that the power efficiency can be increased from 35% to 60%, and the transmitted power can be increased from 1.6 to 45 mW/Volt. [ABSTRACT FROM PUBLISHER]

Recent advances in computational methods, materials science, and new manufacturing processes are resulting in an unprecedented design flexibility which is driving the geometrical complexity of the components found in modern structures and machines. For safety-critical components, the geometrical complexity poses a significant challenge to the sensitivity of the existing nondestructive evaluation (NDE) methods available for the detection of manufacturing defects or damage that develops while a component is in service. Although X-ray computed tomography is the primary NDE method used to test these parts in current industrial practice, it is widely recognized that it has limited sensitivity to critical defects, such as cracks, especially in the presence of large size parts made of dense materials. The lack of sensitive NDE methods represents a major technology gap that could impede the acceptance of rapidly developing technologies, such as 3-D printing, for the production of safety-critical components. This paper attempts to bridge this gap by exploring the possibility of inspecting a complex-shaped part with ultrasonic waves after it has been encapsulated in ice, under the paradigm of what can be defined as cryo-ultrasonic NDE. The underpinning hypothesis is that through ice encapsulation a complex-shaped part can be transformed into a simple-shaped solid whose volume can be probed with ultrasonic waves, which are known to be highly sensitive to both pores and crack-like defects and over a wide range of material properties. Damage detection is then performed by analyzing cross-sectional images of the ice-encapsulated part obtained by applying migration methods to the ultrasonic signals measured by an array of transducers. This paper lays the foundation for cryo-ultrasonic NDE and presents the first experimental results demonstrating the possibility of imaging defects through multiple ice–metal interfaces. This paves the way to the detection of defects in complex-shaped parts containing internal vanes which have so far limited the use of conventional NDE methods. [ABSTRACT FROM PUBLISHER]

This paper investigates how the pitch of elements in periodic ultrasonic arrays is related to their imaging performance, with particular emphasis on imaging artifacts (grating lobes) arising from discrete spatial sampling. Although the classical Nyquist rules for array element pitch are well known, they only provide the limiting condition needed to eliminate grating lobes from an array with an infinitely large aperture at a single frequency. Physical arrays have finite-sized apertures and most applications employ broadband pulses. For these reasons, grating lobe artifacts are always present at some level, and practical array design is, therefore, based on suppressing grating lobe artifacts to a level appropriate to a given application. In this paper, a theoretical framework is developed that enables the point spread function of a periodic imaging array to be decomposed into the sum of contributions from a main lobe and different orders of grating lobes, thus allowing grating lobe artifacts to be unambiguously quantified. Numerical simulations are used to analyze the performance of 1-D linear arrays in both far-field (steering only) and near-field (focusing only) scenarios, and design guidelines are deduced. It is shown that in general, the classical Nyquist rules are overly conservative and that the pitch of an array can be increased without significantly compromising image quality, provided that certain constraints on ray angles are implemented in the imaging algorithm. Experimental examples are shown that illustrate the practical application to arrays in two configurations. [ABSTRACT FROM PUBLISHER]

High-speed ultrasonic vibration cutting (HUVC) applies an ultrasonic vibration to a cutting tool transverse to the cutting direction. The advantage of this method is that the high-speed cutting exceeds the critical cutting speed restrictions of ultrasonic vibration cutting. However, irregular dimple arrays are machined on the work-piece surface, increasing the surface roughness. In this paper, a phase shift control method is proposed, which aims to overlap dimples in a regular pattern to decrease the surface roughness for HUVC. First, this paper investigates the theory of phase shift control to guarantee the surface quality of HUVC. Then, a closed-loop direct digital synthesis (DDS) system is designed to keep the phase shift of the machined dimples stable and controllable. A contrast experiment is conducted to compare the performance of the closed-loop DDS and the open-loop DDS methods in HUVC process. The results show that the closed-loop DDS method can render the dimple phase stable and controllable during the HUVC process. The phase shift value influences the surface roughness. Setting the phase shift to 0.94π with an appropriate feed-rate, the surface roughness is reduced to 0.303, compared to a surface roughness of 0.785 when using the open-loop DDS method. [ABSTRACT FROM PUBLISHER]

Magnetically mediated thermoacoustic imaging (MM-TAI) is an emerging medical electrical parameter imaging technology; it has the advantages of high contrast of electrical impedance imaging and high resolution of ultrasound imaging; it can realize the early diagnosis of disease in the tissues comparing with structure imaging technology. The magnetically mediated thermoacoustic (TA) effect is analyzed in this paper through the theoretical inference, numerical calculation, and experiment. Pulsed excitation is considered in the analysis, which is different from previously reported research. The pulsed magnetic field is applied to the low conductivity sample such as gel phantoms (0.2, 4, and 2.5 S/m); then the Joule heat is generated inside the objects and an acoustic signal is excited due to heat expansion. The acoustic signal is detected and the image is reconstructed from TA source to conductivity. This paper has laid the foundation for the MM-TAI in biological tissues. [ABSTRACT FROM AUTHOR]

Photoacoustic imaging (PAI) is a promising imaging modality due to its high optical specificity. However, the low signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of in vivo PA images are major challenges that prevent PAI from finding its place in clinics. This paper investigates the merit of spatial compounding of PA images in arterial phantoms and the achievable improvements of SNR, when in vivo conditions are mimicked. The analysis of the compounding technique was performed on a polyvinyl alcohol vessel phantom with black threads embedded in its wall. The in vivo conditions were mimicked by limiting the rotation range in ±30°, adding turbid surrounding medium, and filling the lumen with porcine blood. Finally, the performance of the technique was evaluated in ex vivo human carotid plaque samples. Results showed that spatial compounding elevates the SNR by 5–10 dB and CNR by 1–5 dB, depending on the location of the absorbers. This paper elucidates prospective in vivo PA characterization of carotid plaques by proposing a method to enhance PA image quality. [ABSTRACT FROM PUBLISHER]

The ability to design tuned ultrasonic devices that can be operated in the same mode at two different frequencies has the potential to benefit a range of applications, such as surgical cutting procedures where the penetration through soft then hard tissues could be enhanced by switching the operating frequency. The cymbal transducer has recently been adapted to form a prototype ultrasonic surgical cutting device that operates at a single frequency. In this paper, two different methods of configuring a dual-resonance cymbal transducer are detailed. The first approach relies on transducer fabrication using different metals for the two endcaps, thereby forming a dual-resonance transducer. The second employs transducer endcaps composed from a shape memory alloy, superelastic Nitinol. The resonance frequency of the Nitinol transducer depends on the phase microstructure of the material, switchable through the temperature or stress dependence of the Nitinol endcaps. The vibration response of each transducer is measured through electrical impedance measurements and laser Doppler vibrometry, and finite-element analysis is used to show the sensitivity of transducer modal response to the fabrication processes. Through this paper, two viable dual-resonance cymbal transducers are designed and characterized and compared to illustrate the advantages and disadvantages of the two different approaches. [ABSTRACT FROM PUBLISHER]

The traditional evaluation method of vehicle noise can no longer meet the requirements of electric vehicle as the sound character of electric powertrain (E-PT) is totally different from that of internal combustion engine vehicles. This paper presents a complete investigation of the sound quality of an E-PT. An acoustic test is conducted to analyze the sound character of E-PT, based on which the acoustic origins of E-PT including electromagnetic noise, gear whine, and inverter switching noise are studied. After that the sound quality of E-PT is investigated by objective and subjective evaluations. Subsequently, a sound quality model of E-PT based on support vector machine is established. The relative error testifies the effectiveness of the prediction model. The influence of the main noise origins on the sound quality of E-PT is determined. Finally, the structure of gearbox housing is redesigned based on topology optimization to improve the sound quality. The main original contributions of this paper are not only the sound quality method developed for E-PT but also improvement feasibility of sound quality. [ABSTRACT FROM PUBLISHER]

This paper first describes a relation between the frequency and the diameter of columnar soft matter by using broadband ultrasonic single-probe testing. We found an inverse relation between the diameter (100–300 \mu \textm ) and frequency (1.0–6.0 MHz) of the ultrasonic reflection waveform from columnar soft matter in water. This fact shows that we can determine diameters that are not possible to determine by the standard pulse-echo method. An ultrasonic wavelength with center frequency of 15 MHz is limited to measurements of less than 100- \mu \textm thickness in water (wave speed: around 1500 m/s). However, the relation found in this paper enables us to determine these diameters by broadband ultrasonic testing with center frequency of 5.0 MHz, beyond the previous wavelength limitation. Second, this paper proposes a visualization method that uses the discovered relation. An image is produced by using particular frequency components derived via short-time Fourier transform. We employ a phantom consisting of two types of nylon lines, one with thin and the other with thick diameters. The experimental result clearly demonstrated line width and depth beyond the wavelength limitation. [ABSTRACT FROM AUTHOR]

This paper discusses a method of time reversal (TR) for target detection using a signal with a higher signal-to-noise ratio (SNR) and higher resolution. To acquire a signal with a higher SNR and broader spectrum, we have proposed a sensitivity-compensated (SC) signal. In this paper, we propose three types of SC-for-TR signals. An SC-amplitude-modulated (AM)-for-TR signal and an SC-frequency-modulated (FM)-for-TR signal are calculated using squared spectrum compensation. Moreover, to enhance the transmitting energy of a time-reversed wave for a higher SNR, we propose an SC-amplitude-and-frequency-modulated-for-TR (SCAFM-for-TR) signal. The SCAFM-for-TR signal is calculated by AM and FM for deriving a TR wave with a constant envelope waveform and compensated spectrum. In this paper, the efficiency of the SC-for-TR signals is investigated on target ranging in water using pulse compression. Accordingly, the SC-for-TR signals derive a pulse compressed signal with a higher resolution. In addition, the precision of target ranging using the SCAFM-for-TR signal is greater than that using the other SC-for-TR signals at an arrangement when a target was fixed at a position where a signal with a lower SNR is received. These results show that the measurements using the SC-for-TR signals improve time resolution and the SNR. [ABSTRACT FROM PUBLISHER]