Sinusoidal Cycle Research Articles

Oscillatory airflow through the hypopharyngeal and supraglottic airway

Exercise-induced laryngeal obstruction (EILO) is a known cause of exertional dyspnoea, characterised by paradoxical inward collapse of laryngeal tissues. The pathophysiological mechanisms of EILO remain to be fully established, but insufficient mechanical resistance of laryngeal tissues to air-induced loads is hypothesised. It is understood that airflow and anatomic configurations of the airway play a key role in the wall pressure distribution of the larynx. While breathing is a cyclic process with directional changes of airflow, the literature is confined to steady, unidirectional airflow. It is necessary to assess the role of oscillatory airflow on the loads on the laryngeal airway. This study investigates the effect of oscillatory airflow on the laryngeal flow fields and air-induced loads. A computational fluid dynamics model of the upper respiratory tract (URT) is developed using the Reynolds-averaged Navier-Stokes equations. Five oscillatory airflow cases through a single geometry are considered, utilising sinusoidal breathing cycles with different breathing frequencies (24, 32 and 40 breaths per minute) and peak inspiratory flow rates (96, 168 and 240 L/min). Results include the airflow velocity distribution in the URT, and the air-induced pressure and forces. It is demonstrated that inspiratory velocity distribution varies with breathing frequency and intensity. The force acting on the URT walls are in-phase with the airflow rate and therefore exhibit quasi-steady behaviour. These findings are also reflected in the force vectors acting on the aryepiglottic folds and indicate that air-induced closure of the supraglottis in EILO is influenced by the breathing intensity rather than the breathing frequency.

Numerical Study on Static and Fatigue Behavior of Alkali-Activated Fly Ash Concrete Modelled using Concrete Damage Plasticity (CDP) Model

Abstract Alkali-activated concretes (AAC) are considered as an alternative to Portland cement concretes because of their much lower carbon emissions. To study its characteristics is of utmost importance. In the present research, an attempt is made to create a numerical model to analyze the static and fatigue flexural behavior of alkali-activated fly ash concrete (FC) and compare them with ordinary Portland cement concrete (PCC). Three-point bending tests are simulated for the monotonic load to obtain the static behavior of a 2D notched rectangular beam. A 2D beam specimen of size 262.5 mm x 75 mm, with a notch of size 15 mm x 3 mm was provided at the bottom middle. Fly ash-based alkali-activated concrete (FC) and corresponding PCC of similar strength are modeled in ABAQUS CAE using the concrete damage plasticity (CDP) model. The ultimate loads, maximum deflection, and CMOD for each of them were obtained from the history output manager. The results of monotonic tests are utilized for creating a sinusoidal load cycle for fatigue tests with various loading frequencies and stress ratios. Different structural responses are examined under the fatigue test. The results showed that FC performs better than PCC under static and fatigue tests. Fatigue performance of both FC and PCC is influenced by the frequency of loading and fatigue life increases at higher frequencies. It is also found that stress reversal negatively impacts the fatigue life of both FC and PCC.

Analysis of the mechanical response of solid rocket engine propellant under acceleration shock

The increased-range solid rocket engine of new ammunition often needs to withstand extremely high acceleration overload, leading to damage to the propellant’s structural integrity. To address this issue, this paper constructs a nonlinear viscoelastic constitutive model for the CMDB propellant by using low- and high-strain rate mechanical property tests. Combined with the secondary development of explicit dynamics and numerical simulation technology, the mechanical response of a certain type of solid rocket propellant under different acceleration impacts is analyzed. The results show that under acceleration impact loads, the propellant will compress, rebound, and recover over time, continuously cycling. Its axial displacement, maximum equivalent stress, and maximum equivalent strain exhibit irregular sinusoidal wave-like periodic cycles. Looking at the time when the peaks appear, the time when the maximum equivalent stress appears always lags behind the time when the maximum axial displacement peak appears. Due to the viscous effect of the viscoelastic material of the propellant, the time when the equivalent strain peak appears will lag behind the equivalent stress. Because of the material’s damping effect, both the peak values of the maximum equivalent stress and equivalent strain decrease over time. Under continuous high acceleration impact loads, this viscous damping phenomenon continuously diminishes, and the peak value of the propellant’s axial displacement gradually increases.

New Speed Control Scheme for a Three-Phase Induction Machines - (3~IM) Based on Sine Duty Cycle Modulation (SDCM)

This paper proposes a new control scheme for three-phase induction machines based on the sinusoidal duty cycle modulation control strategy combined with V/f control. This technique allows efficient open-loop control of inverter switches. The proposed diagram shows the main characteristics:1 0.1   ,0 50 ,Hzf 21.44 ,base KHzf  2 ,12ref V Vu  . In addition, it guarantees optimum operation of the inverter with the torque and speed parameters of the three-phase induction machine complying with current requirements:10rC Nmmax 6,5A/50Hz/ THD=1,2%

Temperature fluctuations and ventilation dynamics induced by atmospheric pressure variations in Lamalunga Cave (Apulia, Italy) and their influences on speleothem growth

AbstractLamalunga Cave (Altamura, Southern Italy) is renowned for the discovery in 1993 of an excellently preserved Neanderthal skeleton. Given the importance of the findings and the potential use of Lamalunga speleothems for paleoclimate reconstructions, a detailed monitoring program was undertaken to investigate the connections between microclimate parameters and speleothem growth. The cave air temperature is characterized by annual sinusoidal cycles with increasing phase shift and decreasing thermal amplitude from ± 2.1°C to ± 0.04°C as a function of increasing rock overburden, and daily to sub-daily cycles induced by surface air pressure (SAP) variations characterized by strong 24-hour and 12-hour solar harmonic frequencies, with thermal amplitude decreasing from 0.0054°C to 0.0021°C in the deeper parts of the cave. The ventilation regime is mainly controlled by SAP fluctuations. Fast SAP rises can trigger “emptying events” during which most of the cave air is replaced and the CO2 concentration falls towards near-atmospheric values. The steady and gentle ventilation created by SAP fluctuations also influences the growth and morphology of calcite coralloids, with larger popcorn assemblages concentrated in the northern galleries and delicate branching morphologies prevailing along the South Gallery where stable temperature and relative humidity conditions occur. The study is a seminal example of how high-precision measurements of cave air temperature can provide a wealth of information on cave ventilation and thermal regime and provide valuable support for robust paleoclimate reconstruction from speleothems.

Conservative method for vertical electrooculogram attenuation based on local suppression of ongoing EEG artifact templates.

Eye movement during blinking can be a significant artifact in Event-Related Potentials (ERP) analysis. Blinks produce a positive potential in the vertical electrooculogram (VEOG), spreading towards the posterior direction. Two methods are frequently used to suppress VEOGs: linear regression to subtract the VEOG signal from the electroencephalogram (EEG) and Independent Component Analysis (ICA). However, some information is lost in both. The present algorithm (1) statistically identifies the position of VEOGs in the frontopolar channels; (2) performs EEG averaging for each channel, which results in 'blink templates'; (3) subtracts each template from the respective EEG at each VEOG position, only when the linear correlation index between the template and the segment is greater than a chosen threshold L. The signals from twenty subjects were acquired using a behavioral test and were treated using FilterBlink for subsequent ERP analysis. A model was designed to test the method for each subject using twenty copies of the EEG signal from the subject's mid-central channel (with nearly no VEOG) representing the EEG channels and their respective blink templates. At the same 200 equidistant time points (marks), a signal (2.5 sinusoidal cycles at 1050 ms emulating an ERP) was mixed with each model channel and the respective blink template of that channel, between 500 to 1200 ms after each mark. According to the model, VEOGs interfered with both ERPs and the ongoing EEG, mainly on the anterior medial leads, and no significant effect was observed on the mid-central channel (Cz). FilterBlink recovered approximately 90% (Fp1) to 98% (Fz) of the original ERP and EEG signals for L = 0.1. The method reduced the VEOG effect on the EEG after ERP and blink-artifact averaging in analyzing real signals. The method is straightforward and effective for VEOG attenuation without significant distortion in the EEG signal and embedded ERPs.

Radial and longitudinal meniscus tears show different gapping patterns under stance phase conditions.

Meniscal tearing can increase the contact pressure between the tibia and femur by causing gapping of torn meniscus tissue. The aim of this study was to quantify gapping behavior of radial and longitudinal tears and their impact on peak contact pressure and mean contact area. Twelve porcine knee joints underwent unicondylar, convertible osteotomy for exact tear application and consecutive suturing. Six tantalum marker beads were positioned along meniscus tears. The joints were preloaded with sinusoidal loading cycles ranging between 0 N and 350 N. Peak load was held constant and two synchronized Roentgen stereophotogrammetric analysis x-ray images were obtained to evaluate gapping, peak contact pressure and mean contact area in the native, torn and repaired states. There was no change in gapping or peak contact pressure in longitudinal tear. By contrast, the radial tear led to a significant gapping when compared to the native state, while the inside-out suture was able to restore gapping in parts of the meniscus. An increase in contact pressure after radial tear was detected, which was again normalized after suturing. The most important finding of the study is that longitudinal tears did not gap under pure axial loading, whereas radial tears tended to separate the tear interfaces.

Pulsation curves strengthen the high gradient magnetic separation process Ⅱ: Consideration of separation performance

The use of pulsating slurry has been found to be effective in overcoming matrix blockage and improving separation selectivity in high gradient magnetic separators (HGMS). The velocity of the pulsating slurry is regulated by a sinusoidal cycle function, which causes the downward velocity to be much greater than the upward velocity due to the superposition of the sinusoidal pulsation velocity and the feeding velocity. However, the unbalanced velocity configuration in the up-downward stroke limits separation efficiency. This paper investigates the use of asymmetrical pulsation curves in a lab-scale HGMS to balance the velocity configuration and consequently improve separation performance. Magnetic field strength, feed velocity, and pulsating frequency were varied in separate experiments to determine the effect of pulsation curves on separation performance. The asymmetrical pulsation curve with a faster upward stroke and slower downward stroke was found to achieve a TiO2 concentrate grade of 23.94 %, a recovery of 66.78 %, and a separation efficiency of 50.46 % for the separation of ilmenite. When the concentrate grade is slightly higher, this new curve shows an increase of 5.68 % in recovery and 5.05 % in separation efficiency compared to the conventional sinusoidal pulsation curve. This improvement is attributed to a simultaneous strengthening of the material loose-adsorption process by separately regulating the pulsating upward and downward strokes.

Mixed Convection in a Square Cavity Filled with Porous Medium with Bottom Wall Periodic Boundary Condition

Transient mixed convection heat transfer in a confined porous medium heated at periodic sinusoidal heat flux is investigated numerically in the present paper. The Poisson-type pressure equation, resulted from the substituting of the momentum Darcy equation in the continuity equation, was discretized by using finite volume technique. The energy equation was solved by a fully implicit control volume-based finite difference formulation for the diffusion terms with the use of the quadratic upstream interpolation for convective kinetics scheme to discretize the convective terms and the temperature values at the control volume faces. The numerical study covers a range of the hydrostatic pressure sinusoidal amplitude range and time period values of . Numerical results show that the pressure contours lines are influenced by hydrostatic head variation and not affected with the sinusoidal amplitude and time period variation. It is found that the average Nusselt number decreases with time and pressure head increasing and decreases periodically with time and amplitude increasing. The time averaged Nusselt number decreases with imposed sinusoidal amplitude and cycle time period increasing.

A Meta-Heuristic Optimization Procedure for the Identification of the Nonlinear Model Parameters of Hydraulic Dampers Based on Experimental Dataset of Real Working Conditions

Abstract Hydralic dampers are widely implemented in railway vehicle suspension stages, especially in high-speed passenger trains. They are designed to be mounted in different positions to improve comfort, stability, and safety performances. Numerical simulations are often used to assist the design and optimization of these components. Unfortunately, hydraulic dampers are highly nonlinear due to the complex fluid dynamic phenomena taking place inside the chambers and through the by-pass orifices. This requires accurate damper models to be developed to estimate the influence of the nonlinearities of such components during the dynamic performances of the whole vehicle. This work aims at presenting a new parametric damper model based on a nonlinear lumped element approach. Moreover, a new model tuning procedure will be introduced. Differently from the typical sinusoidal characterization cycles, this routine is based on experimental tests of real working conditions. The set of optimal model parameters will be found through a metaheuristic iterative approach able to minimize the differences between numerical and experimental damper forces. The performances of the optimal model will be compared with the ones of the most common Maxwell model generally implemented in railway multibody software programs.

Characterizing the viscoelastic properties of the anterolateral ligament and grafts commonly used in its reconstruction

BackgroundCurrent anatomic anterolateral ligament reconstruction is typically performed using either a gracilis tendon or an iliotibial band graft based on their quasi-static behavior. However, there is limited knowledge about their viscoelastic behaviors. This study aimed to characterize the viscoelastic properties of the anterolateral ligament, distal iliotibial band, distal gracilis tendon and proximal gracilis tendon for graft material choice in anterolateral ligament reconstruction. MethodsAll the tissues were harvested from thirteen fresh-frozen cadaveric knees and subjected to preconditioning (3-6 MPa), sinusoidal cycle (1.2-12 MPa), dwell at constant load (12 MPa), and load to failure (3%/s). The quasi-static and viscoelastic properties of the soft tissues were computed and compared using a linear mixed model (p < 0.05). FindingsThe hysteresis of anterolateral ligament (mean:0.4 Nm) was comparable with gracilis halves (p > 0.85) but iliotibial band (6 Nm) was significantly higher (p < 0.001,ES = 6.5). In contrast, the dynamic creep of anterolateral ligament (0.5 mm) was similar to iliotibial band (0.7 mm, p > 0.82) whereas both gracilis halves were significantly lower (p < 0.007,ES > 1.4). The elastic modulus of anterolateral ligament (181.4 MPa, p < 0.001,ES > 2.1) was the lowest compared to the grafts materials (distal gracilis tendon:835 MPa, distal gracilis tendon:726 MPa, iliotibial band:910 MPa). Additionally, the failure load of the anterolateral ligament (124.5 N, p < 0.001,ES > 2.9) was also the lowest. InterpretationThe mechanical properties of the gracilis halves and iliotibial band were significantly different from anterolateral ligament, except for hysteresis and dynamic creep, respectively. Our findings showed that the gracilis halves may be a more appropriate graft choice for anterolateral ligament reconstruction due to its low energy dissipation and permanent deformation under dynamic loads.

Study on influencing factors of synergistic deformation between built-in strain sensor and asphalt mixture

Strain sensor play an irreplaceable role in monitoring the structural response of asphalt pavements. The effective synergistic deformation of sensor and pavement structure is a key foundation to ensure accurate sensor measurements. The differences between sensor and pavement material lead to complex synergistic deformation between them. Therefore, this study intends to investigate the factors that influence the synergistic deformation of the sensor and the asphalt mixture under different operating conditions. The aim is to reveal the working mechanism of sensor and asphalt mixture synergistic deformation and improve the application value of the measured sensor data. Firstly, by using digital image correlation (DIC) technology and direct tensile beam test, a new test method was designed for the synergistic deformation evaluation of sensor and asphalt mixture. Then, the strain response test was carried out on the asphalt mixture specimens with built-in strain sensor under different stress modes such as multi-stress tension axial compression, tension-compression alternation and sinusoidal cycle. Finally, the numerical value monitored by DIC technology was used as strain reference value to calculate the measurement error of the sensor, and then to analyze the evolution of the synergistic deformation of strain sensor and asphalt mixture. The results show that loading mode and magnitude, temperature and sensor position deviation are the key factors that affect the deformation compatibility between the sensor and the asphalt mixture. The loading frequency has less influence on deformation compatibility. The average absolute error E̅a of the sensor measurement increases as the load increases. The measured strain response shows the opposite measurement deviations under multi-stress tension and axial compression. The strain response accuracy of the sensor drops sharply at high temperatures of 30 °C∼50 °C. At this time, the average absolute error of measurement E̅a and the relative error E̅r can be increased by 3.49–11.79 times and 2.01–2.91 times, respectively. The working environment temperature of the high modulus strain sensor in collaboration with the asphalt pavement should be below 30 °C. Deflection of the position of the embedded sensor will cause the measured value to be smaller. When the deflection angle is 12°, the measurement error of the sensor can be increased by 2.43–5.46 times under the same load. The results provide an important reference for solving the technical problems of incompatibility between built-in strain sensor and asphalt pavement, and promoting the sensor technology to deeply enable traditional asphalt pavement structures.

Evidence for long-term potentiation in phospholipid membranes

Biological supramolecular assemblies, such as phospholipid bilayer membranes, have been used to demonstrate signal processing via short-term synaptic plasticity (STP) in the form of paired pulse facilitation and depression, emulating the brain's efficiency and flexible cognitive capabilities. However, STP memory in lipid bilayers is volatile and cannot be stored or accessed over relevant periods of time, a key requirement for learning. Using droplet interface bilayers (DIBs) composed of lipids, water and hexadecane, and an electrical stimulation training protocol featuring repetitive sinusoidal voltage cycling, we show that DIBs displaying memcapacitive properties can also exhibit persistent synaptic plasticity in the form of long-term potentiation (LTP) associated with capacitive energy storage in the phospholipid bilayer. The time scales for the physical changes associated with the LTP range between minutes and hours, and are substantially longer than previous STP studies, where stored energy dissipated after only a few seconds. STP behavior is the result of reversible changes in bilayer area and thickness. On the other hand, LTP is the result of additional molecular and structural changes to the zwitterionic lipid headgroups and the dielectric properties of the lipid bilayer that result from the buildup of an increasingly asymmetric charge distribution at the bilayer interfaces.

Load distribution and tooth root stress of highly crowned spherical gear couplings working at high misalignment angles

Spherical gear couplings are commonly used mechanical components to transmit power between highly misaligned rotating shafts. For that, gear couplings are manufactured with high longitudinal crowning and are usually small due to space restrictions, with the probability to contain undercutting sections. High misalignment angles cause the number of teeth in contact to decrease drastically, resulting in the failure of the component by tooth root fatigue breakage.This paper investigates the load distribution and the tooth root stress of highly crowned spherical gear couplings working at high misalignment angles using a finite element model. Moreover, a deep understanding of the bending tooth root stresses in terms of the operating conditions is presented, which is novel for such high misalignment angles (γ≥3∘). Results show that different mechanical behaviors are observed at low or high misalignment angles since teeth in the pivoting position lose contact. This results in a tooth root stress history change from a sinusoidal cycle to a pulsating cycle. Finally, this study shows evidence that current sizing methods are not suitable, and underlines the need for further research to determine the spherical gear coupling life to tooth root bending fatigue.

Design and Simulation of Grid-Connected Photovoltaic Single-Phase Inverters

This paper focuses on a new control strategy for single-phase photovoltaic inverters connected to the electrical power distribution network. The inverter studied is single-phase H bridge, equipped with a robust control strategy by sinusoidal duty cycle modulation. This new control strategy offers the advantage over the control strategy. Most used control in its first approximation (PWM control technique): A low Hardware complexity; a variable modulation frequency/period; a topology of modulation with feedback. This inverter structure is further composed of the robust PI controllers, a boost chopper and an LCL filter. The low voltage electrical network to which this inverter is connected is materialized and simulated by a voltage source of characteristics 230V-15A-50Hz and synchronized to the latter by a phase-locked loop (PLL). In this article, the main components of the grid-connected PV power plant are modeled and simulated under Matlab/Simulink as well as the simulation of the global behavior of the entire network+PV inverter and the results obtained are presented.

Visible light-driven degradation of Acid Orange 7 by light modulation techniques

The impact of light modulation on the decolorization of Acid Orange 7 (AO7) in aqueous solution was examined in this paper. A fixed bed batch photocatalytic reactor with a flat plate geometry, irradiated by 240 white-light LEDs, was used. A successful transfer of visible active photocatalyst (N-TiO2) in powder form on a polystyrene (PS) transparent plate was realized. The structured photocatalyst was characterized through SEM–EDX, Raman and UV-DRS analyses, evidencing the formation of a coating of N-TiO2 in the anatase phase, with a band-gap energy of 2.5 eV, and almost uniform distribution on the PS surface. Different LED dimming techniques, with fixed and variable duty-cycle values, were tested, and four types of light modulation were compared: fixed duty cycle (constant irradiation), sinusoidal variable duty cycle (sinusoidal variable irradiation), triangular variable duty cycle (triangular variable irradiation), and square wave variable duty cycle (square wave variable irradiation). The resulting responsiveness/efficiency of the LED versus the current intensity was evaluated, and the stability of the photocatalyst activity and the influence of optimized irradiation waveforms were examined in the decolorization of 400 mL of 10 ppm AO7 solution. The sinusoidal modulation, with current between 50 and 100 mA and 10 s as the period, shows the highest value of the apparent pseudo-first-order kinetic constant, resulting equal to 0.0044 min−1, at parity of total transmitted photons. An energy saving with the application of sinusoidal irradiation is highlighted with respect to the literature.Graphical

Automated electrochemical determination of beer total antioxidant capacity employing microdialysis online-coupled with amperometry

Electrochemical techniques are rarely applied for the evaluation of total antioxidant capacity of beers due to severe electrode inactivation (fouling) by adsorbed oxidation products of the species present in the samples. In this work, we show that microdialysis online-coupled with amperometry is suitable for beer analysis, permitting also an assay automation. The working electrode of the amperometric detector employs a carbon fiber microelectrode that is regenerated between the analyses by short (1 sec) rapid (50 Hz) sinusoidal potential cycling between 0 and 2.9 Vvs Ag/AgCl. This step, along with the sample cleanup by microdialysis effectively removes electrode fouling. The suitability of this approach for beer analysis was studied using eight different beers produced by international manufacturers. The results were compared with standard Kaneda diphenylpicrylhydrazil (DPPH) assay. Steady state currents, obtained at 600 mV vs Ag/AgCl correlate well with the results obtained with Kaneda method and thus can be used for quantification of beers' antioxidant capacities. HPLC-ED of microdialysates with and without DPPH treatment were employed to get an insight into DPPH reactivity with beer components.

Compounding Transient Airfoil Motions and the Effectiveness of Linear Superposition

This paper investigates, for the first time, the effects of compounding transient airfoil motions and the predictive capability of the linear superposition principle in vortex dominated flows. Significant increases in the peak lift and nose-down pitching moment were observed during the second of two transient plunging motions at a poststall angle of attack. The load response of the second motion was estimated through linear superposition of the first motion response with a surprising level of accuracy. Flowfield measurements revealed this performance to coincide with a constructive merging of leading-edge vortices (LEVs). LEV merging showed sensitivity to motion timing. Breakdown of the linear superposition prediction coincided with LEV detachment and trailing-edge vortex formation, which disrupted constructive LEV merging. The amplitude of the second motion showed no discernible effect on LEV merging, and subsequently the accuracy of the linear superposition prediction. An extension to periodic motion was investigated, where linear superposition of a single sinusoidal cycle was compared with the true periodic response. This was found to capture the mean lift increase for low to moderate reduced frequencies. Lift amplitude, however, was captured with reasonable accuracy across the range of reduced frequencies and amplitudes tested.

Design and Characterization of a Planar Micro-Conveyor Device Based on Cooperative Legged Piezoelectric MEMS Resonators.

This paper reports the design, fabrication, and performance of a hybrid piezoelectric planar micro-conveyor based on Micro-Electromechanical Systems (MEMS) bridge resonators and featuring 3D-printed vertical legs. The device includes two cooperating silicon plate resonators with an area of 5 × 1 mm2, actuated by an integrated aluminum-nitride (AlN) piezoelectric thin film. An optimally designed array of 3D-printed projection legs was attached to the plates, to convert the standing-wave (SW) vertical vibrations into horizontal rotations or translations of the supported slider. An open-loop control strategy based on burst-type driving signals, with different numbers of sinusoidal cycles applied on each of the resonators, allowed the cooperation of the two bridges to set up prescribed trajectories of small flat objects, up to 100 mg, with positional accuracy below 100 nm and speeds up to 20 mm/s, by differential drive actuation. The effect of the leg tip and sliders’ surface finish on the conveyor performance was investigated, suggesting that further optimizations may be possible by modifying the tribological properties. Finally, the application of the micro-conveyor as a reconfigurable electronic system, driven by a preprogrammed sequence of signals, was demonstrated by delivering some surface-mount technology (SMD) parts lying on a 65 mg glass slider.

Circular Trajectory Approach for Online Sinusoidal Signal Distortion Monitoring and Visualization

The increasing complexity and uncertainties of modern power systems are placing greater demands on signal monitoring techniques. This letter proposes the Circular Trajectory Approach (CTA) for online sinusoidal signal distortion monitoring and visualization. CTA can detect distortions of a sinusoidal signal. Compared with existing waveform anomaly detection techniques, CTA is faster in detection and less computation intensive. It thus supports edge devices and online applications. CTA also offers a new means of sinusoidal signal distortion visualization. It can reveal the distorted sections in a sinusoidal cycle and clearly display the distortions. The proposed approach is tested on real data from an open source EPRI dataset.