Probe Wave Research Articles

Nonlinear acoustical transmission through a weak shock wave

Recent experiments (Ducousso et al., Phys. Rev. Appl., L051002, 2021) demonstrated the possibility to image weak shock propagation in solids by an ultrasonic probe wave. Wave interaction with a steady, ideal step shock in air has been previously described (Burgers, Selected Papers, Springer, 478–486, 1995—McKenzie and Westphal, Phys. Fluids, 11, 2350, 1968), without consideration for the particular case of a weak shock nor for the influence of the medium. The present paper considers a weak shock interacting in any inviscid fluid with an incident probe wave. No reflected wave arises. The transmitted wave, vortex and entropy modes behind the shock, and the shock front disturbance, are determined by the linearisation of the Rankine-Hugoniot relations. For a weak shock, entropy mode and energy jump relation can be omitted. The shock motion induces a Doppler effect dependant on the medium, air and water giving opposite trends. The transmitted wave amplitude is either increased or reduced through energy exchanges with the shock. For an incidence beyond the critical angle, instead of a total reflexion, an inversion of the direction of the transmitted wave occurs, propagating in the same direction as the shock. This phenomenon seems specific to weak shocks.

Spatial-temporal measurement of waves in laboratory based on binocular stereo vision and image processing

Acquisition of wave field data is essential for hydrodynamics studies. Current studies show deficiencies in the spatial measurement of wave fields in the laboratory, and a more efficient method is urgently needed. A stereo imaging method was proposed for the spatial-temporal measurement of waves in the laboratory based on binocular stereo vision and digital image processing. Then, a series of regular and focused waves were simulated in a wave flume to examine the feasibility and reliability of the method by comparison with the measurements by wave probes. Floating particles were evenly sprinkled on the water surface as the representation of the water-air interface, providing texture features for wave surface images and allowing the realization of dense reconstruction. Synchronized cameras provided the synchronized stereo pairs sequence for each wave, and temporal reconstruction was achieved by processing frame by frame. The 4D spatial-temporal volume for every wave could be constructed. Subsequently, spatial slices of the volume obtained the instantaneous profiles of the wave field in different directions. Temporal slices obtained the wave time series at a fixed point, which were compared with the measurements of the standard resistive probe to verify the accuracy. The results showed that the proposed method was capable of measuring the spatial-temporal field of waves efficiently and precisely and offered the potential to measure more complex wave fields in nonlinear wave-structure interactions.

From Paul Langevin’s quartz sensor to ultrasound metrology of today

This talk focuses on the remarkable impact of Paul Langevin’s research since he (in 1917) proposed to use the piezoelectric properties of quartz for underwater detection of ultrasound signals. Not only has his pioneering idea opened the field of quantitative measurements of acoustic waves, but it also had far-reaching implications for the development of modern ultrasound metrology, driven by the need to ensure the safety of ultrasound used in visualizing of internal human organs for diagnostic applications and maximizing the efficacy and precision of treatment in therapeutic application of ultrasound waves. In summarizing the current advances in ultrasound metrology, a succinct background explaining why, initially, both the scientific community and industry were skeptical about the existence of the nonlinear (NL) wave propagation in tissue will be given and the design of an adequately wideband piezoelectric polymer hydrophone probe that was eventually used to verify that the 1–5 MHz probing wave then used in diagnostic ultrasound imaging was undergoing nonlinear distortion and generated harmonics in tissue will be discussed. [ Work supported by the NIHNINR through Grant No. 5R01NR015995. The contents of this presentation are solely the responsibility of the authors and do not necessarily represent the official views of the NIH.]

Detections of the position-vectors of the multi targets located in a circular space based on an asymmetric coupling semiconductor lasers network.

We present a novel scheme for the detections of the position-vectors of the multi targets distributed in a circular space using multi channels of the probe chaotic waves emitted by the asymmetric coupling semiconductor lasers network (ACSLN), where these probe waves possess the attractive features of the time-space uncorrelation and wide bandwidth. Using these features, the accurate measurement for the position-vectors of the multi targets can be achieved by correlating the multi channels of the probe waves with their corresponding reference waves. The further research results show that the detections for the position-vectors of the multi targets possess very low relative errors that are no more than 0.22%. The ranging-resolutions for the multi targets located in a circular space can be achieved as high as 3 mm by optimizing some key parameters, such as injection current and injection strength. In addition, the ranging-resolutions exhibit excellent strong anti-noise performance even when the signal-to-noise ratio and relative noise intensity appear obvious enhancement. The detections for the position-vectors of the multi targets based on the ACSLN offers interesting perspectives for the potential applications in the driverless cars and the object tracking system with omnidirectional vision.

Gravitational wave and CMB probes of axion kination

Rotations of an axion field in field space provide a natural origin for an era of kination domination, where the energy density is dominated by the kinetic term of the axion field, preceded by an early era of matter domination. Remarkably, no entropy is produced at the end of matter domination and hence these eras of matter and kination domination may occur even after Big Bang Nucleosynthesis. We derive constraints on these eras from both the cosmic microwave background and Big Bang Nucleosynthesis. We investigate how this cosmological scenario affects the spectrum of possible primordial gravitational waves and find that the spectrum features a triangular peak. We discuss how future observations of gravitational waves can probe the viable parameter space, including regions that produce axion dark matter by the kinetic misalignment mechanism or the baryon asymmetry by axiogenesis. For QCD axion dark matter produced by the kinetic misalignment mechanism, a modification to the inflationary gravitational wave spectrum occurs above 0.01 Hz and, for high values of the energy scale of inflation, the prospects for discovery are good. We briefly comment on implications for structure formation of the universe.

Controlling surface plasmon polariton losses in the visible spectrum by temperature-induced interband transitions

We study theoretically the temperature dynamics at the metal-dielectric interface excited by a strong pump surface plasmon polariton pulse propagating along it. We demonstrate that the inclusion of the interband transitions leads to much stronger temperature-induced modulation of the imaginary part of the dielectric constant induced by the pump. We show that in the visible part of the spectrum a strong pump field can even lead to the decrease in the extinction coefficient for the co- or contrapropagating probe wave.

Quantification of the effect of pump wave amplitude on crack breathing for the Nonlinear Coda Wave Interferometry

In civil engineering, an emerging ultrasonic approach based on Code Wave Interferometry (CWI), called Nonlinear Coda Wave Interferometry (NCWI) has been developed to detect microcracks in cementitious materials that cannot be detectedby conventional ultrasonic methods. NCWI uses a high amplitude low frequency (LF) nonlinear pump wave to generate a nonlinear clapping effect at microcracks that can be detected by a high frequency (HF) probe wave. The imaging of cracks inside heterougeneous materials using NCWI requires the inversion technique, which is constitued by model space and data space, in which conatains model parameters and data parameters respectively. In the frame of inversion with NCWI, the model parameter used is the scatetring cross section of a crack sigmaD, and the experimental parameter is the decorrelation coefficient Kd. Knowing that sigmaD depends on the pump wave amplitude. Therefore, in order to introduce NCWI in inversion, the relationship between the pump wave and sigmaD is needed, which is the goal of this study. The dynamic pump wave generates clapping effect at crack tips, the probe wave frequencies are higher than the pump waves’ by an order of magnitude, hence the effect of pump wave on the coda wave is rather averaged. Previous study showed that this clapping effect is equivalent to a single crack length change dL, dL can be related to an equivalent static stress sigma0 which produces the same dL in quasi-static regime, which is equivalent to the dynamic pump wave. Therefore, a relation can be established between sigma0 and sigmaD. This introduces NCWI into the inverison. Then, the theoretical estimation of Kd can be achieved by the simulation of NCWI using 2D Spectral Element Method (SEM2D), combining with the relationship between sigma0 and sigmaD, which can be used later on in the inversion for the crack imaging.

Robust Laboratory Scale Seakeeping Test Wave Measurement Method Use Ultrasonic Sensor

The seakeeping test is one of the tests done in the Indonesia Hydrodynamic Laboratory (IHL) test tank on a model ship or floating unit. In the test tank, a wave can be generated by using electric and mechanic wave flaps that are pre-programmed on a certain condition of the wave, i.e. different frequencies and amplitude. To measure waves, produced by a wave generator, a wave measuring instrument is needed that can measure changes in water level in the test tank. The current wave measuring instrument is in the form of a 600 mm twin wire wave probe. This instrument is can be used to measure waves in the test tank but has limitations because it is only placed in one location without being moved. Another method is developed to be used in making alternative measuring instruments using ultrasonic sensors. In this paper, this alternative wave measuring instrument shows that measuring waves even when moving the measurement point to a new point location or following a towing carriage can be done and gives better measurement results. Based on these results, this new measuring instrument can be used in a more complex configuration test in the tank.

Improvement on Faraday rotation measurement affected by the stray lights on the HL-2A tokamak

Formic-acid (HCOOH, λ = 432.5 μm) laser P olarimeter- I nterferomet er ( PIer ) has been developed on the HL-2A tokamak, which provides 4 channels of line-integrated electron densities and 4 channels of Faraday rotation angles, respectively. Affected by the stray lights arising from the reflection of the probe waves in the optical system, the measurement of Faraday rotation angles was drastically contaminated during the HL-2A experiments, showing an obvious oscillation modulation during the electron density ramp-up/down. This paper introduces an effective correction approach used to improve the accuracy of Faraday rotation measurement on the HL-2A tokamak. Based on the method, the deviation term originating from the stray lights can be effectively subtracted from the contaminated Faraday rotation measurement. The preliminary result indicates that the interference amplitude on Faraday rotation angle is reduced by about 80%, and the corrected data is consistent with the experimental measurement by using the optical isolator that consists of a λ/4 wave-plate and polarizer under the similar discharges.

Long-Range High-Spatial-Resolution Distributed Measurement by a Wideband Brillouin Amplification-Boosted BOCDA

Stimulated Brillouin scattering (SBS)-based distributed fiber optic sensing technique has found pervasive applications in measurement of real-world environmental variables. Its sensing capability, however, is affected by the tradeoff between sensing distance and spatial resolution. Herein, we propose and experimentally verify a wideband Brillouin amplification (WBA)-boosted BOCDA to achieve the high spatial resolution sensing in a longer distance. The WBA is generated by exploiting phase-uncorrelated SBS process between pump and probe waves. Through the WBA, the pump pulses at different scanning frequencies are amplified with the same ratio, which brings distortion-free enhancement of Brillouin signals. The signal-enhancement improves the sensing distance of high spatial resolution BOCDA. As a result, without any additional (Raman/Brillouin) amplification devices, a ∼0.46 MHz measurement certainty and a 6 cm spatial resolution are achieved over a ∼40 km sensing range. The proposed method offers a viable solution for the applications that need high-resolution measurement of remote targets.

Nonlinear-Lamb-wave-based plastic damage detection assisted by topologically designed metamaterial filters

Owing to their high sensitivity to material microstructural defects, nonlinear guided waves (NGWs) show great promise for the early detection of incipient damages, conducive to numerous structural health monitoring (SHM) applications. In an SHM system, however, inevitable non-damage-related nonlinear sources exist, which may overwhelm the damage-induced nonlinear components and in turn jeopardize the practical efficacy of the detection methodology. Therefore, these deceptive nonlinear interferences need to be mitigated or eliminated as much as practically possible. By embracing the concept of metamaterials, a wave filtering device, referred to as a meta-filter (MF), is developed in this paper. The MF is constructed through mounting periodic stubs on the surface of the structure under inspection to condition the probing signals under the second harmonic Lamb-wave-based SHM paradigm. Through topological optimization, the MF enables ultra-wide stop bands to eliminate the second harmonic Lamb waves of the probing waves while preserving their strong fundamental wave components. The band structure and the underlying mechanism, alongside the MF-enabled wave properties, are numerically investigated. Upon tactically introducing deceptive nonlinear sources such as the nonlinear adhesive bonding layers in a piezoelectric transducer-activated SHM system, the performance of the MF is examined from the SHM perspective, which is finally validated experimentally using a metal specimen containing local plasticized incipient damage. Results demonstrate that the designed MF allows for flexible selection of the excitation frequency on one hand, and entails significant enhancement of the detection ability of the NGW-based SHM system on the other hand owing to the customized band features arising from the topological optimization.

Heuristic Detection of the Most Vulnerable Regions in Electronic Devices for Radiation Survivability

As electronic systems become larger and more complex, detection of the most vulnerable regions (MVR) to radiation exposure becomes more difficult and time consuming. We present a heuristic approach where the mechanical and thermal aspects of devices are exploited to quickly identify MVRs. Our approach involves the topological mapping of two device conditions. The first condition identifies regions with the highest mechanical strain or density of defects and interfaces via thermal wave probing and phase analysis. The second condition identifies regions with high electrical field. It is hypothesized that the region with the highest thermal wave penetration resistance and electrical field will exhibit the highest sensitivity to incoming radiation for single events and potentially, total ionizing dose. Our approach implements a simplistic design that improves analysis time by ∼2–3 orders of magnitude over current radiation sensitivity mapping methods. The design is demonstrated on the well-studied operational amplifier LM124, which shows agreement with the literature in identifying sensitive transistors–QR1, Q9, and Q18–with relatively high phase percentile values (>70%) and ΔT percentiles (>50%), satisfying conditions for elevated radiation susceptibility. This is followed by experimental results on a static random access memory (HM-6504) and a Xilinx Artix-7 35 T system on a chip.

Dynamic BOTDA Based on Spectrally Efficient Frequency-Division Multiplexing

The tradeoff between the spatial resolution and estimation accuracy of the Brillouin frequency shift (BFS) sets a technical hurdle for Brillouin optical time-domain analyzers (BOTDAs) based on orthogonal frequency division multiplexing (OFDM), due to orthogonality between the OFDM subcarriers. To solve this problem, a novel BOTDA using spectrally efficient frequency-division multiplexing (SEFDM) is proposed. A partial Zadoff-Chu sequence that generates a centralized pulse after inverse discrete Fourier transform (IDFT) is used. SEFDM signaling is done by discarding the sidelobe of the time domain pulse before being sent as the probe wave. As such, the symbol period is dramatically reduced compared with OFDM signals, leading to a much higher spatial resolution. Meanwhile, the subcarrier spacing of the SEFDM signals remains the same as that of the OFDM signals, which ensures a high estimation accuracy of the BFS if a small subcarrier spacing is used. We experimentally demonstrate a 3.1 m spatial resolution with a 1.294 MHz measurement accuracy in a SEFDM based BOTDA over a 10 km sensing range. Moreover, by using SEFDM signals with very short symbol periods as the probe wave, the time-consuming frequency sweeping process is eliminated, which makes dynamic sensing possible. We successfully demonstrate a dynamic measurement with a vibration frequency of 26 Hz. The introduction of SEFDM provides the desirable flexibility for BOTDAs to be used in both static and dynamic distributed fiber sensing areas with a large dynamic range.

Features of Turbulence Excited by Pulsed High-Frequency Pump in a Magnetoplasma

Turbulence developed in a magnetoplasma modified by a high-power high-frequency pulse fed to a loop antenna is discovered and studied on the large-scale KROT plasma device. Turbulence is manifested in the excitation of the electron density and magnetic field pulsations, deep self-modulation of the pump wave, and modulation of probe waves passing through the modified plasma region. The space–time characteristics of turbulence are determined using correlated plasma density measurements by a pair of miniature microwave resonator probes and a magnetic probe. It is established that turbulence is excited only in the transparency band of the dense magnetoplasma to electromagnetic radiation: turbulent perturbations of the density and magnetic field exist during pumping at frequencies lower than the electron cyclotron frequency and are absent at pumping frequencies exceeding the electron cyclotron frequency.

High-Temperature Ultrasound NDE Systems for Continuous Monitoring of Critical Points in Nuclear Power Plants Structures

High temperature pipe cracks are the root of a steam power failure in the EU typically every 4 years, resulting in loss of human life, serious accidents and massive financial losses. According to IAEA’s Reference Technology Database, such an event on a nuclear power plant has an average cost of €120 million, including outage costs, emergency repair costs, insurance and legal costs. Since only one growing crack is needed to cause a major failure, they have to be inspected and monitored thoroughly. Breakdowns at extreme conditions (e.g. 580°C, 400 bar) are a result of two major weld failure modes: a) creep cracks near pipe welds; b) fatigue cracks on pipe welds. Current maintenance practice is to proceed with repairs on a detected crack according to its severity. For cost reasons, cracks that are not judged as severe enough will not be repaired. Crack severity judgement is based on its probability to cause a failure and this probability is derived taking into account the crack size and operational lifetime. More variables such as operating temperature and vibrations may rarely be found in other studies. Recent data from fracture mechanics statistical studies shows this connection between the size of a crack on a nuclear power plant pipe and its probability to lead to a failure. To deal with the above problems two Structural Health Monitoring (SHM) systems have been developed and they are presented in this work. These systems are able to achieve continuous operation for an extended time period at operating temperatures of nuclear power plants. The developed systems employ novel phased array (PA) ultrasonic and ultrasound guided wave (UGW) probes able to withstand and continuously operate even up to 580 °C. The systems are designed to be permanently mounted on superheated steam pipes, at locations of known defects and to continuously monitor their size. However, this supposes that defects will have already been detected by a traditional method during an outage. The PA transducers are placed according to the Time-of- Flight Diffraction (TOFD) technique’s topology, thus creating a novel configuration, while the UGW transducers are placed on a stainless steel ring in a circular array configuration. These configurations can enable continuous tracking of cracks growth with high accuracy, enabling maintenance crews to estimate the severity directly and not through statistics.

Analysis of Floating Offshore Wind Platform Hydrodynamics Using Underwater SPIV: A Review

There is a need for new numerical tools to capture the physics of floating offshore wind turbines (FOWTs) more accurately to refine engineering designs and reduce costs. The conventional measurement apparatuses in tank tests, including wave probes, velocity and current profilers, and Doppler sensors, are unable to provide a full 3D picture of velocity, pressure, turbulence, and vorticity profile. In tank tests, use of the underwater stereoscopic particle image velocimetry (SPIV) method to fully characterise the 3D flow field around floating wind platforms can overcome some of the limitations associated with classical measurement techniques and provide a rich source of validation data to advance high-fidelity numerical tools. The underwater SPIV method has been widely used for marine and offshore applications, including ship and propeller wakes, wave dynamics, and tidal stream turbines; however, to date, this technology has not seen widespread use for the hydrodynamic study of FOWTs. This paper provides a critical review of the suitability of underwater SPIV for analysing the hydrodynamics of FOWTs, reviews the challenges of using the method for FOWT tank test applications, and discusses the contributions the method can make to mitigating current research gaps in FOWT tank tests.

Leveraging nonlinear wave mixing in rough contacts-based phononic diodes for tunable nonreciprocal waves

In recent years, phononic material-based diodes or “phononic diodes” have been explored to enable nonreciprocal wave propagation for novel applications such as unidirectional filters and waveguides. Despite extensive studies, the functionality and tunability of these diodes have been restricted to specific frequencies. Here, we exploit mixing of double-frequency (pump and probe) waves in nonlinear phononic materials to design a diode that can control the frequency, mode, and direction of energy propagation of the nonreciprocal waves. Our one-dimensional phononic diode is based on local and periodic nonlinearity, and global asymmetry. The weak nonlinearity is incorporated in the form of precompressed rough contacts, where contacts exhibit a quadratic force–displacement relationship. Using finite element models, we demonstrate tuning of the dispersion branch associated with the nonreciprocal wave by controlling the frequency of the pump waves. This allows propagation of nonreciprocal waves at frequencies lower or higher than the probe wave frequencies. Further, we show the ability to switch between reciprocal and nonreciprocal wave propagation, where the nonreciprocal response can cause either unidirectional or bidirectional energy propagation. This switching is possible through suitable selections of a pair of frequencies, and external precompression that controls the band gaps. The proposed phononic diode exhibits nonreciprocal wave propagation over a broad frequency range yet is simple in design and purely mechanical in construction. Moreover, due to its ability to filter and tune the frequencies of nonreciprocal waves, this diode will have potential applications as mechanical sensors and devices.

Data-Driven system identification of 6-DoF ship motion in waves with neural networks

Critical evaluation of ship responses in the ocean is important for not only the design and engineering of future platforms but also the operation and safety of those that are currently deployed. Short-term temporal predictions of ship responses given the current wave environment and ship state would enable enhanced decision-making onboard and reduce the overall risk for both manned and unmanned vessels, especially as the marine industry trends towards more autonomy. However, state-of-the-art numerical hydrodynamic simulation tools are too computationally expensive to be employed for real-time ship motion forecasting. Thus, a methodology is needed to provide fast predictions with levels of accuracy closer to the higher-fidelity tools. A methodology is developed with long short-term memory (LSTM) neural networks to represent the motions of a free running David Taylor Model Basin (DTMB) 5415 destroyer operating at 20 knots in Sea State 7 stern-quartering long-crested irregular seas. Case studies are performed for both course-keeping and turning circle scenarios. An estimate of the vessel’s encounter frame is made with the trajectories observed in the training dataset. Wave elevation time histories are given by artificial wave probes that travel with the estimated encounter frame and serve as input into the neural network, while the output is the 6-DOF temporal ship motion response. Overall, the neural network is able to predict the temporal response of the ship due to unseen wave sequences accurately. The methodology, the dependence of model accuracy on wave probe and training data quantity and the estimated encounter frame are all detailed.

A novel method for steel bar all-stage pitting corrosion monitoring using the feature-level fusion of ultrasonic direct waves and coda waves

Corrosion monitoring of steel bars has drawn extensive attention in recent decades. Conventional ultrasonic method, utilizing direct waves to detect damage, is adequate for severe pitting corrosion but suffers from low sensitivity to incipient pitting corrosion. Coda wave technique, a very sensitive method to subtle changes in medium using later arrival wave packets, is innovatively introduced to monitor pitting corrosion of steel bars, especially in the early stages. The decorrelation coefficient (DC) values are calculated to quantify the variations of both direct waves and coda waves. To overcome the limitations of coda waves for severe pitting corrosion and remedy the low sensitivity of direct waves for incipient pitting corrosion, a feature-level data fusion strategy is proposed to integrate the two probing waves to monitor all-stage pitting corrosion of steel bars. The combination of direct waves and coda waves could exploit the complementary merits in various pitting corrosion configurations. The proposed feature-level fusion strategy of ultrasonic coda waves and direct waves intercepted from the same recorded signals opens a new perspective in all-stage pitting corrosion monitoring of steel bars and contributes a novel scheme for whole-process damage evaluation of structures.

Soliton linear-wave scattering in a Kerr microresonator

The nonlinear scattering of a linear optical wave from a conservative soliton has been widely studied in optical fibers as a mechanism for nonlinear frequency conversion. Here we extend this analysis to consider the scattering of an externally injected probe wave from a dissipative cavity soliton circulating in a Kerr microresonator. We demonstrate, both theoretically and experimentally, that this nonlinear interaction can be harnessed for useful expansion of the soliton frequency comb via the formation of a secondary idler comb. We explore the physics of the process, showing that the phase detuning of the injected probe from a cavity resonance plays a key role in setting the central frequency of the idler comb, thus providing a convenient parameter through which to control the spectral envelope of that comb. Our results elucidate the dynamics that govern the interactions between dissipative Kerr cavity solitons and externally injected probe waves, and could prove useful in the design of future Kerr frequency comb systems by enabling the possibility to provide high-power comb lines in a specified spectral region simply through the injection of a suitably chosen probe.