Electromechanical Wave Propagation Research Articles

Non-destructive testing method of concrete based on piezoelectric sensor

Abstract This paper reviews the research and development of non-destructive techniques for monitoring concrete in the past. Active detection techniques, particularly Electro-Mechanical Impedance method and Wave Propagation method have been demonstrated to be effective in monitoring the concrete process. Electro-Mechanical Impedance method detects internal structural damage by analyzing the vibration characteristics of the structure by combining a piezoelectric transducer with the system to be measured. Compared to the Electro-Mechanical Impedance method, the fluctuation method uses two or more transducers, with one serving as an exciter to actively excite the signal. In contrast, the others form an array to receive the stress wave signal. This method offers several advantages, including the absence of dependence on an impedance meter and passive excitation, a simple operating principle, high response frequency, and high immunity to interference. In this work, the research status and progress in the field of non-destructive testing (NDT) of concrete are combined to summarize the results and refine the methodology of the research on the evaluation of concrete material properties and identification of structural damage; based on this, the bottlenecks, research difficulties and difficulties in the field are further outlined, and finally, the research outlook of NDT of concrete in response to these limitations is put forward.

Parametric analysis of RSB sensors for concrete strength monitoring using hybrid EMI and WP techniques: Numerical investigation

The strength of concrete after its casting increases with time up to a certain limit due to continuous hydration reactions in the cement matrix. To measure the rate of strength development and ultimate capacity of concrete, a novel health monitoring method using Reusable smart bolt (RSB) piezoelectric sensor is proposed in the present paper. The smart piezoelectric Lead zirconate titanate (PZT) patch-based Electro-mechanical impedance (EMI) and Wave propagation (WP) techniques are utilised for accessing the health of concrete at 1, 3, 5, 7, 14, 21 & 28 days of concrete hydration. Firstly, the PZT patch-based sensing capabilities are validated with the experimental results from literature by modelling concrete cube for EMI and beam for WP results. Then, a total of 31 finite element models of concrete cubes having different RSB configurations were taken into consideration for sensor design and optimization. In EMI technique, the shifting of conductance signatures and relative resonance frequency are measured, whereas in WP technique, the shift of P-wave velocity peaks between actuator and sensor is estimated for all the models. The sensitivity of outputs is measured by plotting statistical Root mean square deviation (RMSD) index which proven the efficacy of employing RSB sensors for monitoring concrete strength-development during early-hydration ages with good correlations. Overall, the EMI-identified RMSD plotted for conductance shows 327 % more sensitivity than WP-identified relative change of P-wave velocity in monitoring concrete strength development using RSB sensors.

Imaging Scheme for 3-D High-Frame-Rate Intracardiac Echography: A Simulation Study.

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is normally treated by RF ablation. Intracardiac echography (ICE) is widely employed during RF ablation procedures to guide the electrophysiologist in navigating the ablation catheter, although only 2-D probes are currently clinically used. A 3-D ICE catheter would not only improve visualization of the atrium and ablation catheter, but it might also provide the 3-D mapping of the electromechanical wave (EW) propagation pattern, which represents the mechanical response of cardiac tissue to electrical activity. The detection of this EW needs 3-D high-frame-rate imaging, which is generally only realizable in tradeoff with channel count and image quality. In this simulation-based study, we propose a high volume rate imaging scheme for a 3-D ICE probe design that employs 1-D micro-beamforming in the elevation direction. Such a probe can achieve a high frame rate while reducing the channel count sufficiently for realization in a 10-Fr catheter. To suppress the grating-lobe (GL) artifacts associated with micro-beamforming in the elevation direction, a limited number of fan-shaped beams with a wide azimuthal and narrow elevational opening angle are sequentially steered to insonify slices of the region of interest. An angular weighted averaging of reconstructed subvolumes further reduces the GL artifacts. We optimize the transmit beam divergence and central frequency based on the required image quality for EW imaging (EWI). Numerical simulation results show that a set of seven fan-shaped transmission beams can provide a frame rate of 1000 Hz and a sufficient spatial resolution to visualize the EW propagation on a large 3-D surface.

Monitoring the curing process of in-situ concrete with piezoelectric-based techniques – A practical application

The stiffness and strength properties of freshly poured concrete develop over time as the concrete hardens due to curing. The monitoring of such properties therefore enables timely construction decisions such as formwork removal. Traditional point-in-time destructive tests can be cumbersome, while continuous non-destructive testing is desirable. Piezoelectric-based electromechanical impedance (EMI) and wave propagation (WP) techniques fall into the latter, and they have been verified for monitoring concrete properties during curing in the laboratory. This paper reports the first field application of the EMI and WP techniques for monitoring concrete curing, where smart aggregate (SA) sensors are embedded into concrete pour strips of a multi-storey residential building during construction. For comparison and verification purposes, destructive compression and non-destructive ultrasonic pulse velocity (UPV) tests were conducted. Results obtained from both EMI and WP techniques were consistent and repeatable. They were also comparable to the UPV result, and they showed a close correlation to the compressive strength tests. The current study has also revealed that the electrical signatures acquired from the EMI and WP techniques have a linear relationship. EMI-based and WP-based semi-analytical models (and their derivations) that can quantify the compressive strength and modulus of elasticity of concrete at various curing durations are also presented. This reported study ultimately demonstrates the applicability and practical application of the EMI and WP techniques for real-time measurements, bridging the gap between laboratory-based studies and field applications.

Ultrafast four-dimensional imaging of cardiac mechanical wave propagation with sparse optoacoustic sensing

Propagation of electromechanical waves in excitable heart muscles follows complex spatiotemporal patterns holding the key to understanding life-threatening arrhythmias and other cardiac conditions. Accurate volumetric mapping of cardiac wave propagation is currently hampered by fast heart motion, particularly in small model organisms. Here we demonstrate that ultrafast four-dimensional imaging of cardiac mechanical wave propagation in entire beating murine heart can be accomplished by sparse optoacoustic sensing with high contrast, ∼115-µm spatial and submillisecond temporal resolution. We extract accurate dispersion and phase velocity maps of the cardiac waves and reveal vortex-like patterns associated with mechanical phase singularities that occur during arrhythmic events induced via burst ventricular electric stimulation. The newly introduced cardiac mapping approach is a bold step toward deciphering the complex mechanisms underlying cardiac arrhythmias and enabling precise therapeutic interventions.

A Novel Non-Uniform Frame Structure Model for Power System Disturbance Propagation Analysis

The disturbance propagation mechanism is crucial for the preventive, corrective, and in-extremis control of power grids. This paper proposes a novel non-uniform frame structure model for power system disturbance propagation analysis. A general state transition model of the power grid is derived from the electromechanical wave propagation process. This is further used together with the Gaussian function to derive the non-uniform heterogeneous inertial continuum model, where the non-uniform parameters of the inertia are estimated using the state transition model. The proposed non-uniform frame structure model can be integrated with the electromechanical wave equation to study the disturbance propagation process. These novel developments allow us to tackle the inertial loss and uniform homogenous assumption in existing models. Extensive comparison results carried out on both the chain grid and the IEEE 118-bus system demonstrate that the proposed model can achieve 5- and 3-times accuracy improvements of the state-of-the-art SHU-FSM and ISHU-FSM models, respectively.

Modulation of structure and optical properties micro-fibrils of plants by means of electrical, deformation and optical treatments

Variations of structure and optical properties of micro-fibrils of plants induced by optical, electrical, deformation and water treatments were studied in situ by means of optical polarization microscopy. Bundles of dry fibrils pulled out from nettle, maple and spruce were used for the experiments. Strong enhancement of the optical anisotropy in all of the fibrils has been found just after their wetting with water. Appearance of this anisotropy is attributed to orientation ordering of cellulose molecules in the neighbor layers of the walls of the fibrils. This ordering is explained by penetration of water molecules into the interfaces between cellulose layers and amorphous lignin polymers bound with cellulose molecules in the dry state of the fibrils. Relatively week electrical fields applied to the fibrils removes this anisotropy by pushing out the molecules of water from these interfaces. Evaporation of water returns the fibrils to optically isotropic state as well. The changes of the anisotropy of the fibrils are followed with their deformations These deformations induce internal electrical fields. Hence the interactions of the fibrils with water, electrical and deformation fields result in self-consistent propagation of electromechanical waves along the plants vessels. These waves are capable to transport feeding nutrients. Irradiation of wood components immersed in water by ultraviolet light induces dissolving of lignin and produces pure cellulose fibers. This phenomenon provides the development of new ecologically safety technology of production of cellulose.

On Cyber-Physical Coupling and Distributed Control in Smart Grids

This article focuses on characterizing the impact of communication on distributed control performance in smart grid systems. Using a cyber-physical model of the smart grid and utilizing electromechanical wave propagation in transmission systems, a holistic approach is proposed to unify cyber-physical coupling representation. This is facilitated by establishing an event-propagation paradigm relating measurements, distributed control and the physical power systems network characteristics. We investigate how power system characteristics impose limitations on distributed control performance using the proposed approach. The proposed approach is then used to derive fundamental communication delay limits for effective distributed control, and comparative analysis of distributed control performance is investigated for example distributed control scenarios.

Data-Driven Estimation of Frequency Response From Ambient Synchrophasor Measurements

With the wide deployment of synchrophasor technology, measurement-based dynamic modeling and studies have been becoming increasingly useful for real-time grid operations. This paper considers the problem of estimating the power system frequency response from ambient synchrophasor measurements. Specifically, we develop the analytical conditions for establishing the equivalence between the cross correlation of ambient generator speed data and the system frequency response between any two locations. Our conditions, relying on uniformly damped and equally excited oscillation modes, extend earlier work on electromechanical wave propagation modeling to nonhomogeneous power networks. Numerical results suggest that the validity of the cross correlation approach would hold for more realistic conditions such as nonuniform damping and high-order generator model. Its practical value is further corroborated by real-data results, which closely match with the actual propagation time of electromechanical waves recorded during the 2008 Florida blackout in the Eastern Interconnection system.

Non-Invasive Identification of Inertia Distribution Change in High Renewable Systems Using Distribution Level PMU

This letter proposed an approach to identify the change of inertia distribution in high renewable power systems. Using the footprints of electromechanical wave propagation at the distribution level, this approach provides a new and non-invasive way to aware the system inertia distribution for primary frequency response. Actual measurements and high renewable dynamic models validated effectiveness of the approach.

Observation and Applications of Electromechanical Wave Propagation Based on Wide-Area Synchronous Measurement

Electromechanical wave propagation affects many aspects of power grids, including control and protection. FNET/GridEye, a wide-area distribution-level measurement system, is found to be able to provide unprecedented insight into power system electromechanical wave behavior. This paper discusses the power system electromechanical wave propagation observed in FNET/GridEye and the implementation of algorithms based on wave propagation, including disturbance detection and location, and the development of the propagation speed distribution map.

Wave Aspect of Power System Transient Stability—Part I: Finite Approximation

Electromechanical wave propagation is present in power systems as a transient spatial delay of generator rotor angle variations when a disturbance occurs. The control and mitigation of the this wave phenomenon, which spreads out to different locations at a comparably slow speed, is important for enhancing power system transient stability, as shown in part two of this two-paper series. In an idealized power system consisting of infinitesimal generators and line impedances, this traveling wave can exist to infinite frequencies, its speed can be derived from a wave equation and its reflection can be eliminated by a characteristic termination. Part one of this paper series examines realistic power systems with finite size generators and line impedances. It shows that there is a finite approximation of the traveling wave in real power systems as the wave can exist only within a finite frequency range. This paper also examines aspects such as reflections due to discrete elements, controller design based on the load modulation effect, and the existence of traveling wave and its attenuation in the Australian power system.

Disturbance location determination based on electromechanical wave propagation in FNET/GridEye: a distribution‐level wide‐area measurement system

This study presents a method to locate power system disturbances using wide-area synchropahsor measurements. The merits of the proposed method include robustness and ease of visualisation. In addition, the proposed method facilitates the calculation of electromechanical wave propagation speed distribution. Examples of locating the disturbance and generating the propagation speed distribution are demonstrated using the FNET/GridEye system, a distribution-level wide-area measurement system. Without losing generality, the proposed method can be implemented in any other wide-area measurement system.

An Approach for Estimating Disturbance Arrival Time Based on Structural Frame Model

With the development of power grid interconnection, disturbance propagation phenomena are more and more apparent in the form of electromechanical waves. Once a disturbance occurs, its propagation might cause cascading events and even large blackouts. With the help of advanced communications networks in smart grids, new event-based protection systems can be devised by the reveal of disturbance propagation mechanisms. In this paper, a widely used measurement-based protection system is analyzed and the idea of event-based protection is proposed. By introducing the inverse process of lumped mass method, the impact scope of generator inertia is proposed. Then, the structural frame model of power networks for disturbance propagation is built, which is sectionalized homogeneously. The spatial heterogeneity of propagation velocity of the electromechanical waves is depicted. According to the constant velocity characteristic of the segments in the structural frame model, a weighted undirected graph is formulated. Then, the Dijkstra algorithm based shortest path searching method for arrival time of electromechanical wave is proposed. The simulations are carried out to demonstrate the effectiveness of the proposed electromechanical wave propagation model and disturbance arrival time estimation algorithm. The research work is one of the essential steps for realizing event-based protection strategies.

Modified Continuum Mechanics Modeling on Size-Dependent Properties of Piezoelectric Nanomaterials: A Review.

Piezoelectric nanomaterials (PNs) are attractive for applications including sensing, actuating, energy harvesting, among others in nano-electro-mechanical-systems (NEMS) because of their excellent electromechanical coupling, mechanical and physical properties. However, the properties of PNs do not coincide with their bulk counterparts and depend on the particular size. A large amount of efforts have been devoted to studying the size-dependent properties of PNs by using experimental characterization, atomistic simulation and continuum mechanics modeling with the consideration of the scale features of the nanomaterials. This paper reviews the recent progresses and achievements in the research on the continuum mechanics modeling of the size-dependent mechanical and physical properties of PNs. We start from the fundamentals of the modified continuum mechanics models for PNs, including the theories of surface piezoelectricity, flexoelectricity and non-local piezoelectricity, with the introduction of the modified piezoelectric beam and plate models particularly for nanostructured piezoelectric materials with certain configurations. Then, we give a review on the investigation of the size-dependent properties of PNs by using the modified continuum mechanics models, such as the electromechanical coupling, bending, vibration, buckling, wave propagation and dynamic characteristics. Finally, analytical modeling and analysis of nanoscale actuators and energy harvesters based on piezoelectric nanostructures are presented.

Dynamic analysis of a piezoelectric augmented beam system with adhesive bonding layer effects

Embedded and surface bonded piezoelectric wafers have been widely used for control and monitoring purposes. Several nondestructive evaluation and structural health monitoring techniques, such as electromechanical impedance and wave propagation–based techniques, utilize piezoelectric wafers in either active or passive manner to interrogate the host structure. The basis of all these techniques is the energy transfer between the piezoelectric wafer and the host structure which takes place through an adhesive bonding layer. In this article, the high-frequency dynamic response of a coupled piezoelectric-beam system is modeled including the adhesive bonding layer in between. A new three-layer spectral element is developed for this purpose. The formulation of this new element takes into account axial and shear deformations, in addition to rotary inertia effects in all three layers. The capabilities of the proposed model are demonstrated through several numerical examples, where the effects of bonding layer geometric and material characteristics on dispersion relations and damage detection capabilities are discussed. The results highlight the importance of accounting for the adhesive bonding layer in piezoelectric-structure interaction models, especially when the high-frequency dynamic response is of interest.

Fuzzy Logic PSS Assisted by Neighboring Signals to Mitigate the Electromechanical Wave Propagation in Power Systems

This paper deals with the mitigation of electromechanical wave propagation in power systems. Different conventional controllers addressed this problem, such as the conventional PSS and the conventional fuzzy logic PSS. In this paper, the fuzzy logic PSS is assisted by auxiliary signals from the fuzzy logic PSS of the interconnected machines to augment the damping of electromechanical wave propagation and the associated oscillations. The neighboring machines speed deviation and its derivatives signals are exploited through the fuzzy logic PSS to assist the local fuzzy logic PSS. The disturbance propagation and reflection phenomena are considered in the design of the adopted strategy. The efficacy of the proposed assistance of the conventional fuzzy logic PSS are examined through different simulation results. DOI: http://dx.doi.org/10.11591/telkomnika.v14i3.7837

Simulation Study on Electromechanical Disturbance Propagation in Large Power System

Power systems are subjected to all kinds of random disturbances, showing the electromechanical dynamic. A lot of theoretical researches show that the disturbance power and frequency is propagating in the form of wave which is called electromechanical wave. But electromechanical wave theory is not widely used in actual power system. In this paper we focus on simulation study of electromechanical wave frequency sensitivity and propagation velocity and elaborating the simulation results with the electromechanical wave theory. Finally some summaries and expectations on electromechanical wave study are made.

High-contrast ultrafast imaging of the heart

Noninvasive ultrafast imaging of intrinsic waves such as electromechanical waves or remotely induced shear waves in elastography imaging techniques for human cardiac applications remains challenging. In this paper, we propose ultrafast imaging of the heart with adapted sector size by coherently compounding diverging waves emitted from a standard transthoracic cardiac phased-array probe. As in ultrafast imaging with plane wave coherent compounding, diverging waves can be summed coherently to obtain high-quality images of the entire heart at high frame rate in a full field of view. To image the propagation of shear waves with a large SNR, the field of view can be adapted by changing the angular aperture of the transmitted wave. Backscattered echoes from successive circular wave acquisitions are coherently summed at every location in the image to improve the image quality while maintaining very high frame rates. The transmitted diverging waves, angular apertures, and subaperture sizes were tested in simulation, and ultrafast coherent compounding was implemented in a commercial scanner. The improvement of the imaging quality was quantified in phantoms and in one human heart, in vivo. Imaging shear wave propagation at 2500 frames/s using 5 diverging waves provided a large increase of the SNR of the tissue velocity estimates while maintaining a high frame rate. Finally, ultrafast imaging with 1 to 5 diverging waves was used to image the human heart at a frame rate of 4500 to 900 frames/s over an entire cardiac cycle. Spatial coherent compounding provided a strong improvement of the imaging quality, even with a small number of transmitted diverging waves and a high frame rate, which allows imaging of the propagation of electromechanical and shear waves with good image quality.

Detection of Electromechanical Wave Propagation Using Synchronized Phasor Measurements

Abstract Considering electrical network as a continuum has become popular for electromechanical wave analysis. This paper reviews the concept of electromechanical wave propagation. Analysis of large number of generator ring system will be an easy way to illustrate wave propagation. The property of traveling waves is that the maximum and minimum values do not occur at the same time instants and hence the difference between these time delays can be easily calculated. The homogeneous, isotropic 10 generator ring system is modeled using electromagnetic transient simulation programs. The purpose of this study is to investigate the time delays and wave velocities using Power System Computer Aided Design (PSCAD)/Electromagnetic Transient Program (EMTP). The disturbances considered here are generator disconnections and line trips.