Wave Measurements Research Articles

Nano-modified epoxy coatings: An effective method for sustainable construction

Corrosion in reinforced concrete (RC) structures is an increasingly prevalent issue in the construction industry. Thus, reducing corrosion and strengthening concrete structure would help sustain the environment. This study is centred around the development of epoxy coatings modified with nano-clay and graphene derivatives including multi-walled CNT (Graphene Oxide (GO), and reduced Graphene Oxide (rGO)). Prepared coatings matrix applied on mild steel bar and embedded in concrete specimen for testing for accelerated corrosion. The study evaluated the effectiveness of epoxy coatings modified with nanoparticles using various non-destructive methods, including visual inspection, impressed current corrosion testing, and ultrasonic-guided wave measurements. The non-destructive testing results were further supported by the findings from destructive testing. Ultrasonic studies showed that nano-clay coating is 1.5 times better than PE, however GO/CNT showed no corrosion onset after 60 days of corrosion testing. PE coatings lost 2–3% more mass than nano-clay coatings, while GO/CNT coatings lost 98% less mass as represents in destructive testing. Nano-clay coatings minimize tensile strength loss by 9% than PE coatings, whereas GO/CNT coatings lower it by 98–99%. Overall, graphene-based coatings are more effective in corrosion inhibition than nano-clay coatings. Suggested modification increase infrastructure life by several factors and reduces maintenance, promoting sustainable construction.

Fast Fourier transform Ångström method for fast thermal measurements of microfibers.

The Ångström method is a promising thermal diffusivity measurement method for microfibers. Based on the heat-loss Ångström method and micro-Ångström method, the FFT (Fast Fourier Transform) Ångström method can be used to shorten the testing time and enhance the testing robustness of thermal conductivity. The FFT Ångström uses multi-frequency superimposed input signals and then uses the FFT for frequency division analysis. Since different frequencies are input at the same time, the measuring time is greatly reduced. Moreover, because different frequencies are input in the same environment, the random and environmental perturbations of the frequencies are the same, enhancing the fitting robustness. In contrast, the single feeding strategy is relatively time-consuming, and its measurement homogeneity for different frequencies cannot be guaranteed. By comparing the measurement results from a multi-frequency input and separated single-frequency input, the FFT shows good feasibility and robustness. It may also have great potential in other types of thermal wave measurements.

Changes Induced by the Containment Measures of the First COVID-19 Wave: A Scoping Review on Work-Family Balance Regarding Working Parents

In March 2020, COVID-19 was declared a worldwide pandemic. To limit its spread, governments and institutions have implemented drastic measures with major repercussions on the labor market, workers, and their families. Business, school, and daycare closures, as well as telework and home-schooling, have challenged working parents. In this unique context, researchers have examined COVID-19’s effects on work and family. Using the PRISMA-ScR guidelines, this scoping review explores, classifies, synthesizes, and analyzes the research findings from the first wave of the COVID-19 pandemic on work-family balance issues. More specifically, it examines how contextual forces hindered or facilitated working parents’ time management and work-family balance, along with coping strategies they implemented. Searches were conducted in 18 databases to identify relevant French or English peer-reviewed empirical articles published before April 2021. Articles should include information on parent workers at the first wave of the pandemic. Of the 570 papers identified, 56 were retained and synthesized. The articles cover worldwide populations, with one-quarter from the USA. Based on the Decision-action model, a thematic analysis allows identifying how the experience of the early months of the pandemic affects the life course of working parents and the work-family balance project considering the contextual forces to which they were exposed, and the strategies deployed to meet their needs. Findings reveal the fragility of the work-family balance among working parents and the disorganization caused by a major social crisis. They also highlight the importance of individual, organizational and governmental strategies to better support workers, families, businesses and communities.

Scaling of Moored Surface Ocean Turbulence Measurements in the Southeast Pacific Ocean

AbstractEstimates of turbulence kinetic energy (TKE) dissipation rate (ε) are key in understanding how heat, gas, and other climate‐relevant properties are transferred across the air‐sea interface and mixed within the ocean. A relatively new method involving moored pulse‐coherent acoustic Doppler current profilers (ADCPs) allows for estimates of ε with concurrent surface flux and wave measurements across an extensive length of time and range of conditions. Here, we present 9 months of moored estimates of ε at a fixed depth of 8.4 m at the Stratus mooring site (20°S, 85°W). We find that turbulence regimes are quantified similarly using the Obukhov length scale and the newer Langmuir stability length scale , suggesting that ocean‐side friction velocity implicitly captures the influence of Langmuir turbulence at this site. This is illustrated by a strong correlation between surface Stokes drift and that is likely facilitated by the steady Southeast trade winds regime. In certain regimes, , where is the von Kármán constant and is instrument depth, and surface buoyancy flux capture our estimates of well, collapsing data points near unity. We find that a newer Langmuir turbulence scaling, based on and , scales ε well at times but is overall less consistent than . Monin‐Obukhov similarity theory (MOST) relationships from prior studies in a variety of aquatic and atmospheric settings largely agree with our data in conditions where convection and wind‐driven current shear are both significant sources of TKE, but diverge in other regimes.

Love Wave Tomography of the United States

AbstractLove wave phase velocity maps provide essential constraints on radial anisotropy and deformation in the crust and upper mantle. However, the phenomenon of overtone interference causes scatter and systematic bias in the velocity measurements and impedes efforts to image small‐scale anisotropic variations. We develop an approach for identifying Love wave measurements that are biased by overtone interference, demonstrate its efficacy with EarthScope USArray data, and determine the first earthquake‐derived Love wave phase velocity maps for the entire conterminous U.S. in the period range 35–75 s. We show that radial anisotropy in parts of the crust and most of the lithospheric mantle is necessary to reconcile these maps with Rayleigh wave phase velocities. Our results convey the impact and geographic variability of overtone interference, offer an easy‐to‐implement method to ameliorate this impact, and present high‐resolution constraints on radial anisotropy beneath North America.

On the Constant-Roll Tachyon Inflation with Large and Small ηH

We study the constant-roll tachyon inflation with large and small η. In previous studies, only the constant-roll tachyon inflation with small η is consistent with the observations. We find that the duality between the constant-roll tachyon inflation with large and small η may exist. The apparent duality suggests that the constant-roll tachyon inflationary model with large η may also be consistent with the observations. By fitting the spectral tilde ns and tensor to scalar ratio r, which is a measure of primordial gravitational waves with the observations, we get small and large η in this range −0.01629≤ηH≤−0.00079 and 3.00081≤ηH≤3.01621 at the 2σ C.L for N=60 efolds.

The Mission Support System (MSS v7.0.4) and its use in planning for the SouthTRAC aircraft campaign

Abstract. The Mission Support System (MSS) is an open source software package that has been used for planning flight tracks of scientific aircraft in multiple measurement campaigns during the last decade. It consists of three major components: a web map server located close to the model data storage site that is capable of producing a variety of 2-D figures from 4-D meteorological data; a client application capable of displaying the figures in combination with the planned flight track and an assortment of additional information; and a new collaboration server component that enables real-time collaboration of multiple remote parties. During the last decade, these components were constantly improved towards being simple to set up and use and being standard compliant. Here, we describe the use of MSS during the Southern Hemisphere Transport, Dynamics, and Chemistry–Gravity Waves (SouthTRAC-GW) measurement campaign in 2019. This campaign, based in Rio Grande, Argentina, used the German research aircraft HALO to investigate several scientific objectives related to the Southern Hemisphere chemistry and dynamics. We present the diverse data products offered by the MSS web map server dedicated to the campaign, which were derived from the European Centre for Medium-Range Weather Forecasts (ECMWF) forecast data, Chemical Lagrangian Model of the Stratosphere (CLaMS) simulations, and Atmospheric Infrared Sounder (AIRS) near-real time brightness temperature measurements. As an example for how the MSS software is used in conjunction with the different data sets, we describe the planning of a single flight, which eventually took place on 12 September 2019, probing orographic gravity waves propagating up into the lower mesosphere.

Use of a Compliant Tether to Decouple Observation Buoy Motion for Auxiliary Wave Power

Abstract With the growth of the Blue Economy, the volume of data collection within the ocean environment has been rapidly increasing. Larger numbers of oceanographic, meteorological, and floating Light Detection And Ranging (LiDAR) buoys have been collecting high fidelity measurements while pushing against power budget limits. Power limitations lead to infrequent transmission of reduced data sets or recording data to local storage that must be physically collected when the buoy is serviced. Triton Systems, Inc. and its partners are developing a retrofittable wave energy converter (WEC) to provide auxiliary power to these observation buoys to increase mission duration and power budget, improve reliability, and reduce the need for service trips. One of the greatest challenges has been developing a method to interface Triton's WEC with these buoys without impacting measurement fidelity. This is especially critical for inertial wave and LiDAR wind measurements collected with sensors that could be adversely affected by additional buoy dynamics introduced by an integrated WEC. To address this, Triton and EOM Offshore developed a compliant tether to pair an observation buoy with a floating WEC while decoupling relative motion. Based on EOM's proven stretch hose technology, this compliant tether transmits power and data between the buoy-WEC system. Modeling shows that the system has the potential to minimally adversely affect oceanographic, meteorological, wind resource characterization, and other measurements, with future testing scheduled to validate modeling efforts.

Prediction of Arterial Stiffness Risk in Diabetes Patients through Pulse Wave Velocity and Deep Learning Techniques

Diabetes and arterial stiffness are the primary health concerns related to each other. The understanding of both factors provides efficient disease prevention and avoidance. For the development of cardiovascular disease, arterial stiffness and Diabetes are pathological process considerations. The existing researchers reported the association of these two factors and the complications of arterial stiffness with Diabetes are still in research. Arterial stiffness is measured through pulse wave velocity (PWV), which influences cardiovascular disease in diabetic patients. Moreover, this study developed a medical prediction model for arterial stiffness through the machine and deep learning models to predict the patients who are high-risk factors. Brachial–ankle pulse wave velocity (baPWV) and fasting blood glucose (FBG) are the consideration of baseline. Gaussian-Least absolute shrinkage and selection operator (LASSO) with whale optimization is proposed for feature selection. Initially, key features are extracted from the wave measurement using LASSO, and Principal component analysis (PCA) has been used to remove the outliers. Second, Gaussian regression chooses the PWV-based relevant features from the LASSO identified features. The parts are the critical points to increasing the accuracy of the prediction model. Hence, the selected features are further improved with an evolutionary algorithm called the cat optimization approach. Third, the prediction model is constructed using three machine and deep learning algorithms such as a Support vector machine (SVM), a convolution neural network (CNN), and Gated Recurrent Unit (GRU). The performance of these methods is compared through the area under the receiver operating characteristic curve metric in the dataset. The model with the best performance was selected and validated in an independent discovery dataset (n = 912) from the Dryad Digital Repository (https://doi.org/10.5061/dryad.m484p). From the experimental evaluation, LSTM performs better than other algorithms in classifying arterial stiffness with the AUROC of 0.985 and AUPRC of 0.976.

Societal Applications of HF Skywave Radar

After exploratory research in the 1950s, HF skywave ‘over-the-horizon’ radars (OTHR) were developed as operating systems in the 1960s for defence missions, notably the long-range detection of ballistic missiles, aircraft, and ships. The potential for a variety of non-defence applications soon became apparent, but the size, cost, siting requirements, and tasking priority hindered the implementation of these societal roles. A sister technology—HF surface wave radar (HFSWR)—evolved during the same period but, in this more compact form, the non-defence applications dominated, with hundreds of such radars presently deployed around the world, used primarily for ocean current mapping and wave measurements. In this paper, we examine the ocean monitoring capabilities of the latest generation of HF skywave radars, some shared with HFSWR, some unique to the skywave modality, and explore some new possibilities, along with selected technical details for their implementation. We apply state-of-the-art modelling and experimental data to illustrate the kinds of information that can be generated and exploited for civil, commercial, and scientific purposes. The examples treated confirm the relevance and value of this information to such diverse activities as shipping, fishing, offshore resource extraction, agriculture, communications, weather forecasting, and climate change studies.

The effects of dispersion on time-of-flight acoustic velocity measurements in a wooden rod

The stiffness of wood can be estimated from the acoustic velocity in the longitudinal direction. Studies have reported that stiffness measurements obtained using time-of-flight acoustic velocity measurements are overestimated compared to those obtained using the acoustic resonance and bending test methods. More research is needed to understand what is causing this phenomenon. In this work, amplitude threshold time-of-flight, resonance, and guided wave measurements are performed on wooden and aluminium rods. Using guided wave theory, it is shown through simulations and experimental results that dispersion causes an overestimation of time-of-flight measurements. This overestimation was able to be mitigated using dispersion compensation. However, other guided wave techniques could potentially be used to obtain improved measurements.

The effects of planform morphology on two-dimensional wave transformation over near-horizontal shore platforms

Shore platforms fronting cliffs have highly irregular planform configurations that could modify the alongshore distribution of wave energy, thereby influencing cliff erosion. However, research aiming to understand the geomorphological control of platform morphology on two-dimensional wave transformation remains scarce. We conducted detailed wave measurements within the intertidal zone of three commonly observed mesoscale planform geometries (straight, concave and convex seaward edges). Waves were measured using a phased array of pressure transducers near the seaward edge of three near-horizontal shore platforms in New Zealand. Waves were analysed at infragravity (IG: 0.002–0.05 Hz) and swell frequencies (SW: 0.05–0.125 Hz), with wave energy derived from the zeroth moment wave height, directional wave spectra derived from the Extension of the Maximum Entropy Method and phase lag derived from the cross-spectrum characteristics. Results showed that wave translation occurred on the straight edge platform, divergence on the concave platform, and convergence on the convex platform. These patterns generated areas of wave ray convergence and divergence over the platforms. Wave energy convergence coincided with increased IG energy and reduced SW energy decay, whereas divergence had the opposite effects. Wave reflection generated cross-shore standing IG waves, for which nodal states varied alongshore with platform width. These phenomena resulted in alongshore variations in normalised wave energy Ê over the three platforms, which were more pronounced for IG than for SW. Compared to the straight platform, alongshore variations of IG were twice as large on the concave platform and three times larger on the convex platform. This study shows that planform morphology impacts along-platform wave energy distribution. These effects likely influence planform rock coast evolution and should be considered in future numerical modelling studies.

Directional wave measurements from navigational buoys

In-situ wave measurements are often required by marine industry standards and for verification of coastal wave forecasts. Obtaining wave measurements is costly and it would be advantageous to utilize existing platforms like navigational buoys designed for environmental monitoring. In this study, a wave sensor module (MOTUS Wave Sensor, Aanderaa Data Instruments) installed on a navigational buoy (Tideland) and a coastal buoy (EMM2.0) is validated against a dedicated wave measurement buoy (Waverider, Datawell). The validation is based upon four months of measurements off the west coast of Norway. The results show that the MOTUS sensor on-board navigational/coastal buoys provide accurate measurements of wave parameters compared to Waverider. Wave height biases were less than 0.04 m over the full wave spectra, and less than 5% for frequencies between 0.05 and 0.45 Hz (0.01 Hz bin width). Mean wave direction bias for the full spectra was 1.4 and 2.8 degrees, and less than 5 and 10 degrees in frequency bins between 0.05 and 0.45 Hz for the navigational and coastal buoy, respectively. External compass measurements were required for accurate directional measurements for the coastal buoy. The validated wave sensor provides in-situ directional wave measurements with measurement uncertainties well within recommended accuracy levels.

Space-time statistics of extreme ocean waves in crossing sea states

The study of extreme ocean waves has gained considerable interest in recent years, due to their importance for offshore design and navigation safety, and several theoretical approaches have been developed for their statistical description. However, in the case of crossing seas, where two or more wave systems of different characteristics are present, a full understanding of the main physical mechanisms responsible for the occurrence of very high individual waves is still lacking. As a consequence, the prediction of extremes in such conditions currently relies on integrated parameters of the total sea state, such as the spectral wave steepness. In this study, to gain further insight into the role of the crossing wind sea and swell wave systems in producing extreme individual waves, we investigate realistic sea states during typhoon Kong-rey (2018) using an ensemble of numerical simulations obtained from a phase-resolving wave model based on the High-Order Spectral (HOS) method. The reliability of the numerical fields is assessed for the first time with stereo wave measurements of the sea surface elevation field collected from an offshore platform in the area of interest. We show that, in specific conditions, space-time extreme crest heights in crossing seas can be larger than in unimodal seas due to second-order bound wave interactions between the wind sea and the swell. To improve existing prediction capabilities, we propose a novel formulation for the wave steepness in crossing seas, which includes nonlinear effects up to the second order and accounts for the spectral parameters of the interacting wave systems.

Estimation of the Rod Velocity in Wood using Multi-frequency Guided Wave Measurements

This study presents a new approach for measuring the acoustic “rod velocity” in wood using guided wave measurements. The approach fits the acoustic guided wave longitudinal L(0,1) wave mode dispersion curve, through experimental guided wave phase velocity measurements taken over a range of frequencies. The rod velocity is obtained by measuring the phase velocity of the fitted L(0,1) wave mode dispersion curve at zero frequency. This technique is used to obtain rod velocity measurements for cylindrical wood and aluminium samples. The same approach was also performed on resonance measurements at a wide range of harmonics. These rod velocities are then compared to acoustic velocities obtained using the traditional time of flight and resonance methods.

Investigation of the relationship between tensile viscoelasticity and unloaded ultrasound shear wave measurements in ex vivo tendon

Mechanical properties of biological tissues are of key importance for proper function and in situ methods for mechanical characterization are sought after in the context of both medical diagnosis as well as understanding of pathophysiological processes. Shear wave elastography (SWE) and accompanying physical modelling methods provide valid estimates of stiffness in quasi-linear viscoelastic, isotropic tissue but suffer from limitations in assessing non-linear viscoelastic or anisotropic material, such as tendon. Indeed, mathematical modelling predicts the longitudinal shear wave velocity to be unaffected by the tensile but rather the shear viscoelasticity. Here, we employ a heuristic experimental testing approach to the problem to assess the most important potential confounders, namely tendon mass density and diameter, and to investigate associations between tendon tensile viscoelasticity with shear wave descriptors. Small oscillatory testing of animal flexor tendons at two baseline stress levels over a large frequency range comprehensively characterized tensile viscoelastic behavior. A broad set of shear wave descriptors was retrieved on the unloaded tendon based on high frame-rate plane wave ultrasound after applying an acoustic deformation impulse. Tensile modulus and strain energy dissipation increased logarithmically and linearly, respectively, with the frequency of the applied strain. Shear wave descriptors were mostly unaffected by tendon diameter but were highly sensitive to tendon mass density. Shear wave group and phase velocity showed no association with tensile elasticity or strain rate-stiffening but did show an association with tensile strain energy dissipation.The longitudinal shear wave velocity may not characterize tensile elasticity but rather tensile viscous properties of transversely isotropic collagenous tissues.

Improvement of wave predictions in marginal seas around Korea through correction of simulated sea winds

One of the main error sources in predicting ocean surface waves is the uncertainty of numerical sea wind products used as input to wave prediction models. In particular, the complexity of atmospheric physics and limitations of numerical computation in time and space increase the uncertainty of numerical sea winds in the area of marginal seas. So, a process is proposed to improve wave prediction in marginal seas by correcting numerical sea-wind products (i.e., herein, ERA5 wind reanalysis data produced around the Korean Peninsula). To evaluate and correct the ERA5 data, Korea Meteorological Administration (KMA) buoy and MetOp-B (ASCAT) satellite data were used. In the procedure, firstly, the ASCAT winds in space were calibrated using the buoy data, and secondly the calibrated satellite winds were used to evaluate and correct the ERA5 wind data. Finally, the corrected ERA5 wind data were used as input to a numerical wave model (i.e., WAVEWATCH-Ⅲ). When the corrected wind data were applied to the wave numerical model, the resulted predictions showed a better match to the in situ wave measurements. In the results, the bias error was reduced from (0.21 to 0.04) m, and the best fit slope was improved from (0.84 to 0.93) on average, compared to the predictions by the original sea winds. This procedure can be applied to other marginal seas in which sea winds are strongly influenced by neighbouring continents, and not well reproduced by numerical approaches.

Correlation of Shear-Wave Elastography and Apparent Diffusion Coefficient Values in Breast Cancer and Their Relationship with the Prognostic Factors.

Diffusion-weighted imaging and elastography are widely accepted methods in the evaluation of breast masses, however, there is very limited data comparing the two methods. The apparent diffusion coefficient is a measure of the diffusion of water molecules obtained by diffusion-weighted imaging as a part of breast MRI. Breast elastography is an adjunct to conventional ultrasonography, which provides a noninvasive evaluation of the stiffness of the lesion. Theoretically, increased tissue density and stiffness are related to each other. The purpose of this study is to compare MRI ADC values of the breast masses with quantitative elastography based on ultrasound shear wave measurements and to investigate their possible relation with the prognostic factors and molecular subtypes. We retrospectively evaluated histopathologically proven 147 breast lesions. The molecular classification of malignant lesions was made according to the prognostic factors. Shear wave elastography was measured in kiloPascal (kPa) units which is a quantitative measure of tissue stiffness. DWI was obtained using a 1.5-T MRI system. ADC values were strongly inversely correlated with elasticity (r = -0.662, p < 0.01) according to Pearson Correlation. In our study, the cut-off value of ADC was 1.00 × 10-3 cm2/s to achieve a sensitivity of 84.6% and specificity of 75.4%, and the cut-off value of elasticity was 105.5 kPa to achieve the sensitivity of 96.3% and specificity 76.9% to discriminate between the malignant and benign breast lesions. The status of prognostic factors was not correlated with the ADC values and elasticity. Elasticity and ADC values are correlated. Both cannot predict the status of prognostic factors and differentiate between molecular subtypes.

Multi‐Event Analysis of the Correlation Between Chorus Waves and Electron Butterfly Distribution Using Van Allen Probes Observation

AbstractIn this study, using Van Allen Probes observations we identify 81 events of electron flux bursts with butterfly pitch angle distributions for tens of keV electrons with close correlations with chorus wave bursts in the Earth's magnetosphere. We use the high‐rate electron flux data from Magnetic Electron Ion Spectrometer available during 2013–2019 and the simultaneous whistler‐mode wave measurements from Electric and Magnetic Field Instrument Suite and Integrated Science to identify the correlated events. The events are categorized into 67 upper‐band chorus (0.5–0.8 fce) dominated events and 14 other events where lower‐band chorus (0.05–0.5 fce) has modest or strong amplitudes (fce represents electron cyclotron frequency). Each electron flux burst correlated with chorus has a short timescale of ∼1 min or less, suggesting potential nonlinear effects. The statistical distribution of selected electron burst events tends to occur in the post‐midnight sector at L > 5 under disturbed geomagnetic conditions, and is associated with chorus waves with relatively strong magnetic wave amplitude and small wave normal angle. The frequency dependence of the electron flux peaks agrees with the cyclotron resonant condition, indicating the effects of chorus‐induced electron acceleration. Our study provides new insights into understanding the rapid nonlinear interactions between chorus and energetic electrons.

Real-time precise measurements of ocean surface waves using GNSS variometric approach

Real-time precise measurements of ocean surface waves using GNSS variometric approach