Maximum Response Amplitude Research Articles

Особливості спазмолітичної дії препарату «Беластезин»

Мета дослідження – порівняльне вивчення спазмолітичної активності препарату «Беластезин», таблетки та атропіну на моделі ацетилхолін-залежної скоротливої активності (міогенної та нейрогенної) ізольованих смужок гладеньких м’язів кишківника (ГМК) мурчаків. Дослідження було проведене на 10 мурчаках-самцях (масою 300–350 г). Для запобігання можливості інтерферуючого впливу бензокаїну на скоротливі реакції гладеньких м’язів вилучення алкалоїдів з таблеткової маси проводили у водному розчині, а на смужках ГМК тестували лише фракції водорозчинних сполук. Зважаючи на загальну подібність механізму дії та фізіологічних ефектів, специфічну активність Беластезину порівнювали з атропіну сульфатом. Введення досліджуваного препарату та атропіну в діапазоні концентрацій (10–9–10–6 моль/л) у камеру зі смужками одночасно з ацетилхоліном (АХ) (10–6 моль/л) викликало зниження амплітуди та інтегральної інтенсивності АХ-стимульованої скоротливої активності ГМК. Беластезин відрізнявся від атропіну за характером антагоністичної взаємодії з М-холінорецепторами, про що свідчили зміни в нахилі кривої «концентрація-ефект» (рівняння Больцмана). Беластезин у діапазоні низьких концентрацій (10–10–10–7 моль/л) підвищував інтенсивність скоротливої діяльності смужок у разі електростимуляції, тоді як атропін знижував скоротливу активність ГМК. Відмінності в дії препарату, які були відмічені за умов функціонального тесту, дозволяють висловити припущення, що Беластезин виявляв активність більш характерну для скополаміну (гіосцину), ніж для атропіну (гіосціаміну). В умовах дозозалежної АХ-стимуляції скоротливої активності ГМК Беластезин викликав суттєве зрушення кривих «концентрація-ефект» порівняно з помірним ефектом атропіну. Досліджуваний препарат також зменшував амплітуду максимальної відповіді на відміну від атропіну. Отримані результати свідчать про те, що природна суміш алкалоїдів у складі Беластезину більш ефективна, ніж атропін щодо усунення спастичної діяльності гладеньких м’язів, яка спричинена стимуляцією М-холінорецепторів.

Exploiting Nonlinear Dynamics for Design Optimization of Periodic Response of Harmonically Excited, Piezo-Driven, Buckled Beams

Abstract Design of piezo-electric actuated cutting tools requires carefully controlling the response characteristics while minimizing the energy input for an efficient design. Many times, nonlinearities are seen as a burden in cutting tool design process as they can result in unpredictable and extremely sensitive response. As such, engineers make design changes to effectively minimize or completely eliminate the nonlinear behavior and that has been a practice in biomedical device design industry. In this paper, the periodic response of buckled beams under piezo-excitation is considered. An optimization approach, as first demonstrated in Refs. [1] and [2], is utilized that achieves maximum amplitude, periodic, and stable responses of the beam systems. Case studies are presented that demonstrate the utility of this optimization approach to exploit the nonlinear dynamics to achieve desired responses. This work presents a new, global optimization driven, computational design approach for medical devices while exploiting nonlinearity in response dynamics.

Effect of rounded corners on flow-induced vibration of a square cylinder at a low Reynolds number of 200

Flow-induced vibration of a square cylinder with rounded corners at a low Reynolds number of 200 is investigated numerically. Simulations are conducted for a mass ratio of 10, a damping ratio of 0 and non-dimensional radius (R) of the rounded corners ranging from 0 (square cylinder) to 0.5 (circular cylinder). The principal aim of this study is to find out the effects of the rounded corner on vortex-induced vibration and galloping, which are typical phenomena of an elastically mounted square cylinder in fluid flow. Galloping is fully suppressed if R is greater than 0.1 inclusive, and greatly mitigated as R = 0.03 and 0.05 and still exists with large amplitude if R = 0.01. However, the rounded corner is found to broaden the VIV lock-in regime and also increases the maximum response amplitude in the lock-in regime. The maximum non-dimensional amplitude in the lock-in regime increases from 0.26 to 0.57 as R increases from 0 to 0.5. Rounded corner also affects the beating phenomenon in the VIV lock-in regime. The beating is type A beating when R is small and type B beating when R is large. In type A beating, the vibration frequency varies around the natural frequency, while in type B beating, the vibration frequency varies between the vortex shedding frequency and natural frequency. In the galloping regime both the vibration displacement and the lift coefficient have dual frequencies: a low vibration frequency and a high vortex shedding frequency. The dominant frequency of the lift coefficient is the vortex shedding frequency instead of the vibration frequency.

3D LES simulations of a static and vertically free-to-oscillate 4:1 rectangular cylinder: Effects of the grid resolution

Vortex induced vibration (VIV) is an important phenomenon which appears in flexible structures immersed in a moving fluid. This oscillation is self-sustained and self-limited, but VIV might cause fatigue damage and affect the structure's serviceability.In the present study, the aerodynamics of the flow fields around a static and vertically free-to-oscillate 4:1 rectangular cylinder are analysed by means of 3D LES simulations, adopting the OneEqEddy viscosity model. Integral parameters, pressure distributions, amplitudes of oscillation, coherences and correlations are obtained and compared with the available experimental data. Aiming to ascertain the impact of the boundary conditions and the grid resolution on the accuracy of results, five cases adopting 3 different meshes including two different spanwise discretisations have been considered. When studying the aerodynamics of the cylinder in static conditions, the influence of the spatial discretisation is very limited, and the agreement with experimental data is fairly good. On the other hand, for the free-to-oscillate cylinder, the structural response is dramatically dependent on the spanwise discretisation. The maximum amplitude of the structural response decreases as the mesh resolution increases, providing a closer fit with the experimental data. Also, the spanwise correlation of pressures is studied, finding remarkable differences depending on the level of spatial discretisation.

Multi-frequency effect towards High Conductivity Overburden Responses using Horizontal Coplanar (HCP) coil configuration for Landslide Hazard Instrumentation

The instrumentation for the sensing of natural disaster phenomena as like as landslide instrumentation has acquired great importance for the instrumentation community. The novel instrumentation for landslide application has been made and calibrated using Horizontal Coplanar (HCP) coil orientation. The early instrumentation for landslide slopes was gradually equipped with standard and automatic instrumentation consisting of three the piezometric cells, two deep-seated steel wire extensometers, four in clinometric tubes, a rainfall gauge, a snow gauge and an air thermometer. This novel instrumentation works in electromagnetic methods similar with electromagnetic methods in geophysics. HCP coil orientation is a coplanar array where both coils are horizontal. In HCP, the depth of sounding is about 1.5 times of the coils separation which have maximum coupled configuration (HCP, VCP, and Vertical Coaxial configuration). The overburden response had inverted the percent value of maximum negative response then there were three maximum response amplitude peaks. Measurement and data processing were performed using a computer through Delphi program. The diagonal cross sections of the overburden as the centre were the maximum value of inverted response of anomaly positions. In aluminium thin plate overburden, the diagonal cross section point as the overburden centre was the maximum value of inverting value of the highest minimum response amplitude. The measurement graphic in the computer screen with several types of overburdens would be displayed. As the result, that the overburden widths for overburden were determined by subtracted of two turning points positions. The overburden positions were accurate for Type P overburden. The master curve had a high anomaly contrasts with two of positive anomaly peaks. Otherwise, the anomaly positions were between two of the negative anomaly peaks.

THE UTILITY OF PUPILLARY LIGHT REFLEX AS AN OBJECTIVE BIOMARKER OF ACUTE CONCUSSION IN THE ADOLESCENT ATHLETE

Background: Visual deficits and autonomic dysfunction have been well recognized following pediatric concussion. Testing of the pupillary light reflex (PLR) is a simple, non-invasive, and objective approach to examine the autonomic nervous system by accessing the brain pathways. The aim of this study was to objectively evaluate adolescent pupillary responses to a light stimulus after a physician-diagnosed concussion and compare them to baseline responses. Methods: In this prospective cohort study, PLR was assessed in 135 adolescent athletes (ages 14-18) during their sport pre-season. All of the athletes were not recovering from a concussion at the time of their baseline assessment. Within this cohort, seven athletes (ages 14-17) sustained a concussion during their sport season and had longitudinal post-injury assessments of PLR through their recovery. The PLR was obtained in response to a brief step-input (0.8 seconds) white light stimulus using a hand-held pupillometer (stimulus recording duration= 5 seconds, light intensity= 150 lux). Pre-set and automated device-generated parameters used for analysis include the minimum and maximum pupil diameter, response amplitude and latency, mean constriction and dilation velocities and the maximum constriction velocity of the eye in response to a light stimulus. During each assessment, three monocular trials were performed in each eye alternatively, and the responses for each eye were subsequently averaged. Results: Six out of the seven concussed adolescents showed response enhancement of about 20% (IQR 11-33%). Enhancement was noted in the steady state diameter with a mean of 24% (median 18%), minimum pupil diameter mean of 17% (median 11%) and maximum constriction velocity mean of 28% (median 33%) following concussion, which decreased during the recovery process (days to weeks post-injury) to pre-injury or below initial pre-injury baseline measurements. Pupillary responsivity was found to be significantly enhanced after concussion compared to baseline measurements, waning over time. Maximum constriction velocity better highlighted the enhancement compared to the baseline pupil diameter. Conclusions/Significance: Pupil responsivity was found to be significantly enhanced after concussion compared to baseline measurements which waned over time during recovery. Assessment of dynamic PLR responses has potential utility as an objective biomarker to aid in concussion diagnosis on the sidelines or in the office, allowing physicians to quantify function (and dysfunction) of the autonomic nervous system under parasympathetic and sympathetic control after concussion.

Steady-State Visually Evoked Potentials Elicited by Multifrequency Pattern-Reversal Stimulation.

PurposeIt has been shown that multifrequency stimulation with multifocal electroretinography can reduce recording time without a loss in signal-to-noise ratio. Here, we studied the applicability of multifrequency stimulations for steady-state visually evoked potential (VEP) recordings.MethodsMultifrequency VEPs were recorded monocularly from 10 healthy subjects using pattern-reversal stimuli. The reversal frequency varied between 5 and 30 Hz. Pattern-reversal checkerboard stimuli were generated using four square arrays, each containing 100 light-emitting diodes (LEDs), positioned in four quadrants. Each array had a temporal frequency that differed slightly from the nominal frequency. The long duration of the data acquisition ensured that the slightly different stimulus frequencies in the four LED arrays can be resolved and that the responses to the stimulus in each array can be distinguished (e.g., with a frequency resolution: 0.011 Hz at 12 Hz). The best response from the four recording electrode configuration, defined as the recording with the maximal signal-to-noise ratio, was used for further analysis. Algorithmic latencies were calculated from the ratio of phase data and frequencies in a range of 4 and 20 Hz.ResultsQuadrant-VEPs with simultaneous pattern-reversal stimulation yielded a significant dependency on temporal frequency and stimulus location. The frequency range leading to the maximal response amplitude was between 10 and 12 Hz. Response phases decreased approximately linearly, with increasing temporal frequency suggesting a mean algorithmic latency between 112 and 126 ms.ConclusionsMultifrequency stimulation using LED arrays is an efficient method for recording pattern-reversal VEPs while all stimuli are presented at the same time.Translational RelevanceSimultaneously recorded VEPs as performed by the multi-frequency method can be used for objective measurements of visual field defects.

Three-dimensional CFD analysis of damping effects on vortex-induced vibrations of 2DOF elastically-mounted circular cylinders

This paper presents results for three-dimensional computational fluid dynamics analysis for one and two degrees-of-freedom (DOF) elastically mounted rigid cylinders with different damping ratios subjected to vortex-induced vibrations. Simulations were conducted with a cylinder allowed to move in the cross-flow direction and a cylinder allowed to move in the stream-wise and cross-flow directions. Numerical simulations were carried out for constant mass ratio of m*=2.4 with Reynolds number in the range of 1.5×103 to 3.5×104. A classically damped spring-mass system was programmed inside the numeric solver for simulating the responses of the cylinders. Damping ratios of ζ=1.25, 5, 10 and 20% were considered. High damping ratios and Reynolds numbers, which lack of data in the literature, are considered. In the present study, the effects of the damping ratio on the response amplitude and on the vortex wake patterns are investigated. Simulations were efficiently conducted using a new approach for mesh deformations. New set of data was obtained for the diagram of maximum response amplitude versus damping-mass parameter presented by Khalak & Williamson (1999) [1]. For 1 and 2DOF dynamics, the maximum amplitude decreases and the transition from the lock-in regime to the Strouhal law vibration frequency is anticipated by the damping ratio. In addition, the Reynolds number effects on the cross-flow response amplitude were observed to be dependent on the damping-mass parameter, m*ζ. Further, it was observed that opposite frequency responses can be found for system with similar m*ζ values.

Lamb Wave Directional Sensing with Piezoelectric Fiber Rosette in Structure Health Monitoring

Directional piezoelectric sensors can detect the Lamb wave propagation direction to locate damage in structural health monitoring (SHM). The directivity of the round piezoelectric fiber is exploited with a 0°/45°/90° rosette configuration to acquire flexural Lamb wave signals. The directional response of the piezoelectric fiber under narrowband tone‐burst excitation is theoretically deduced. Experimental tests are conducted to demonstrate the directivity and the frequency response property of the piezoelectric fiber under different excitation central frequencies in comparison with the MFC, rectangular piezoelectric sheet, and circular piezoelectric disc. Continuous wavelet transform (CWT) is applied to extract the maximum response amplitude information of the acquired Lamb wave signal at a central frequency. Experimental test results indicate that the piezoelectric fiber is capable to be used as a Lamb wave directional sensor than other piezoelectric sensors. A numerical estimation method for the Lamb wave propagation direction is proposed by defining an error function between the theoretical and experimental normalized response amplitude. The proposed method is generally applicable for different rosette configurations. Experimental results validate the accuracy of the proposed estimation method. The research results are significant to design or select the piezoelectric sensor to measure Lamb wave signals.

Nonlinear resonant behaviors of embedded thick FG double layered nanoplates via nonlocal strain gradient theory

This research deals with the nonlinear forced vibration behavior of embedded functionally graded double layered nanoplates with all edges simply supported via nonlocal strain gradient elasticity theory based on the Mindlin plate theory along with von Karman geometric nonlinearity. The interaction of van der Waals forces between adjacent layers is included. For modeling surrounding elastic medium, the nonlinear Winkler–Pasternak foundation model is employed. The exact solution of the nonlinear forced vibration for primary and secondary resonance through the Harmonic Balance method is then established. For the double layered nanoplate, uniform distribution and sinusoidal distribution of loading are considered. It is assumed that the material properties of functionally graded double layered nanoplates are graded in the thickness direction and estimated through the rule of mixture. The Galerkin-based numerical technique is employed to reduce the set of nonlinear governing equations into a time-varying set of ordinary differential equations. The effects of different parameters such as length scale parameters, elastic foundation parameters, dimensionless transverse force and gradient index on the frequency responses of functionally graded double layered nanoplates are investigated. The results show that the length scale parameters give nonlinearity of the hardening type in nonlinear forced vibration and the increase in strain gradient parameter causes to increase in maximum response amplitude, whereas the increase in nonlocal parameter causes to decrease in maximum response amplitude.

Numerical Study on the Influence of Mass and Stiffness Ratios on the Vortex Induced Motion of an Elastically Mounted Cylinder for Harnessing Power

Harnessing the power of vortices shed in the wake of bluff bodies is indeed a boon to society in the face of fuel crisis. This fact serves as an impetus to develop a device called a hydro vortex power generator (HVPG), comprised of an elastically mounted cylinder that is free to oscillate in the cross-flow (CF) direction even in a low velocity flow field. The oscillatory motions in turn can be converted to useful power. This paper addresses the influence of system characteristics viz. stiffness ratio (k*) and mass ratio (m*) on the maximum response amplitude of the elastically mounted cylinder. Computational fluid dynamics (CFD) simulations have been used here to solve a two way fluid–structure interaction (FSI) problem for predicting the trend of variation of the non-dimensional amplitude Y/D with reduced velocity Ur through a series of simulations. Maximum amplitude motions have been attributed to the lowest value of m* with Ur = 8. However, the maximum lift forces correspond to Ur = 4, providing strong design inputs as well as indicating the best operating conditions. The numerical results have been compared with those of field tests in an irrigation canal and have shown reasonable agreement.

Transient amplitude amplification of mistuned structures: An experimental validation

Until now, only few works have dealt with the transient vibration response of bladed disks of turbomachinery. However, transient vibration of turbines has become more and more important due to the changes on the energy production sector. Recently, it has been theoretically demonstrated that the maximum amplitude of the resonance passage of mistuned blisks may even exceed the maximum amplitude of the steady-state response. This effect is called transient amplitude amplification of mistuned structures (TAMS). The phenomenon is investigated within this article. By using a lumped mass model, it is shown how the maximum amplitude of the steady-state solution may be exceeded by the maximum amplitude of the resonance passage. Further, the occurrence of transient amplitude amplification of mistuned structures is experimentally validated.A new experimental set-up is designed to perform a resonance passage. Hence, an accelerated traveling wave type excitation is created. Loudspeakers are used to perform a contactless excitation. With the designed test rig, the occurrence of TAMS can be demonstrated. The results are the first experimental proof that the maximum of a transient vibration response can exceed the maximum of the stationary vibration response of the same dynamic system.

Dynamic reliability prediction of vehicular suspension structure with damping random uncertainties

This research is conducted such that a two degrees of freedom nonlinear stochastic vibration model of vehicular suspension structure with random bilinear damping forces and cubic nonlinear restoring forces is established. Based on extreme value theory (EVT) and Monte Carlo integration method (MCIM), a novel method of predicting the failure probabilities of the maximum amplitude responses of suspension structure is proposed. The extreme value distribution functions of amplitude responses, which are analytical expressed by underlying amplitude distribution functions, are acquired by using EVT. In order to obtain the analytical expressions of the underlying distribution functions, histograms are used to estimate their distribution forms. Under the log-normal distribution assumption, the means and standard deviations of the underlying distributions are calculated by using MCIM, and then by setting up amplitude failure levels, the extreme distribution functions and failure probabilities of amplitude responses are obtained. The Monte Carlo simulation method-based numerical analyses give enormous supports to use of the proposed prediction means.

Beneficial stiffness design of a high-static-low-dynamic-stiffness vibration isolator based on static and dynamic analysis

A high-static-low-dynamic-stiffness (HSLDS) isolator has good application prospects in low-frequency vibration and micro-vibration isolation. The nonlinear stiffness of the vibration isolation system strongly influences its dynamic responses and vibration isolation performance. In this paper, for a HSLDS isolator model, a stiffness range parameter d and a static equilibrium position stiffness Ksep are introduced to indicate the different stiffnesses of the nonlinear isolator. The averaging method is employed to solve the nonlinear dynamic equation of the proposed system at steady state for each excitation frequency. The effects of the parameters d and Ksep on the dynamic responses and isolation effectiveness of the HSLDS isolator are clearly analysed. The results show that an increase in d and a reduction in Ksep improve the isolation performance of the system. Considering the application of the HSLDS isolator in micro-vibration environments, the beneficial stiffness design under various excitation amplitudes and damping conditions is discussed on the basis of the limited maximum response amplitude. Several useful guidelines for the stiffness design of the HSLDS isolator are developed, which help to improve the vibration isolation performance of the system. The results provide useful insight for the design, analysis and application of HSLDS vibration isolators.

Geometric Development of Point Absorber Wave Energy Conventer

This paper describes how to design the shape of a floating object that will be used as a point absorber on wave energy converster. The buoyant shape to be analyzed is a tube has a flat top plane with varying bottom plane, i.e cylinder, hemisphare and cone. The analysis was conducted on the diameter of the object and the influence of the ocean wave period on the area where the apparatus was later applied in the southern coast of East Java. Using Moses's software, it is found that the diameter of the body is proportional to the period in which the maximum of Response Amplitude Operator floating object. The object with a flat bottom field (cylinder) produces the largest period, which is 10 s, followed by a curve shape of a hemisphere with a period of 9 s and last with a cone shape cone with a period of at least 8 s. This shows that the curvature of the bottom of the buoyancy can be adjusted according to the wave period to obtain maximum Response Amplitude Operator.

Detection of electric current pulses by a fibre-optic sensor using spun fibre

We have studied distinctive features of the response of a fibre-optic current sensor with a spun-fibre sensing loop to short current pulses. It has been shown theoretically that, in a reflective interferometer, the polarisation mode dispersion (PMD) in the sensing spun fibre has no effect on the pulsed output signal of the sensor, in contrast to the PMD in a connecting fibre line. The response of the current sensor to a rectangular pulse has linear edges and its duration is determined by the relationship between the current pulse duration and the light propagation time in the spun fibre. The transition from a linear edge to the maximum sensor response is not accompanied by any transient process. The maximum response amplitude corresponds to the response to an equivalent direct current at a current pulse duration exceeding the light propagation time in the spun fibre. The present calculation results and experimental data agree well for current pulses longer than 300 ns at a light propagation time in the spun fibre of ~1 μs.

Convergence of linear acceleration and yaw rotation signals on non-eye movement neurons in the vestibular nucleus of macaques.

Roughly half of all vestibular nucleus neurons without eye movement sensitivity respond to both angular rotation and linear acceleration. Linear acceleration signals arise from otolith organs, and rotation signals arise from semicircular canals. In the vestibular nerve, these signals are carried by different afferents. Vestibular nucleus neurons represent the first point of convergence for these distinct sensory signals. This study systematically evaluated how rotational and translational signals interact in single neurons in the vestibular nuclei: multisensory integration at the first opportunity for convergence between these two independent vestibular sensory signals. Single-unit recordings were made from the vestibular nuclei of awake macaques during yaw rotation, translation in the horizontal plane, and combinations of rotation and translation at different frequencies. The overall response magnitude of the combined translation and rotation was generally less than the sum of the magnitudes in responses to the stimuli applied independently. However, we found that under conditions in which the peaks of the rotational and translational responses were coincident these signals were approximately additive. With presentation of rotation and translation at different frequencies, rotation was attenuated more than translation, regardless of which was at a higher frequency. These data suggest a nonlinear interaction between these two sensory modalities in the vestibular nuclei, in which coincident peak responses are proportionally stronger than other, off-peak interactions. These results are similar to those reported for other forms of multisensory integration, such as audio-visual integration in the superior colliculus. NEW & NOTEWORTHY This is the first study to systematically explore the interaction of rotational and translational signals in the vestibular nuclei through independent manipulation. The results of this study demonstrate nonlinear integration leading to maximum response amplitude when the timing and direction of peak rotational and translational responses are coincident.

Study on the dynamic performance of concrete mixer's mixing drum

Abstract. When working, the geometric distribution shape of concrete in concrete mixing truck's rotary drum changes continuously, which cause a great difficulty for studying the dynamic performance of the mixing drum. In this paper, the mixing system of a certain type of concrete mixing truck is studied. A mathematical formulation has been derived through the force analysis to calculate the supporting force. The calculation method of the concrete distribution shape in the rotary drum is developed. A new transfer matrix is built with considering the concrete geometric distribution shape. The effects of rotating speed, inclination angle and concrete liquid level on the vibration performance of the mixing drum are studied with a specific example. Results show that with the increase of rotating speed, the vibration amplitude of the mixing drum decreases. The peak amplitude gradually moves to the right with the inclination angle increasing. The amplitude value of the peak's left side decreases when tilt angle increases, while the right side increases. The maximum unbalanced response amplitude of the drum increases with the decrease of concrete liquid level height, and the vibration peak moves to the left.

Assessing Absolute Maximum Vibration Amplitude of a Rectangular Plate Subjected to a Moving Mass

Dynamic behavior of bridges under moving loads is a challenging engineering problem, which has attracted a great interest in a myriad of papers and books in structural dynamics field. In case of a slab-type bridge, a plate influenced by a traversing mass can reflect the full two-dimensional mechanical behavior of the supporting structure. This paper investigates absolute maximum response amplitude of a plate-type structure subject to a moving mass. To this end, the absolute maximum dynamic deflection of a rectangular plate under a moving mass is sought at all interior points of it, while the existing literature is restricted to capturing maximum values at the plate center point. Unlike the conventional methods that seek maximum dynamic response at the center point of the plate, extracting absolute maximum response—which does not necessarily take place at the center point—is an onerous task and computationally demanding. According to the findings of the current paper, accurate values of the plate maximum vibration amplitude significantly differ from those maximum responses obtained at the plate center point.

Energy harvesting from quasi-periodic vibrations using electromagnetic coupling with delay

In this paper, we study quasi-periodic vibrational energy harvesting in a delayed self-excited oscillator with a delayed electromagnetic coupling. The energy harvester system consists in a delayed van der Pol oscillator with delay amplitude modulation coupled to a delayed electromagnetic coupling mechanism. It is assumed that time delay is inherently present in the mechanical subsystem of the harvester, while it is introduced in the electrical circuit to control and optimize the output power of the system. A double-step perturbation method is performed near a delay parametric resonance to approximate the quasi-periodic solutions of the harvester which are used to extract the quasi-periodic vibration-based power. The influence of the time delay introduced in the electromagnetic subsystem on the performance of the quasi-periodic vibration-based energy harvesting is examined. In particular, it is shown that for appropriate values of amplitudes and frequency of time delay the maximum output power of the harvester is not necessarily accompanied by the maximum amplitude of system response.