Dispersion Fluctuations Research Articles

Broadband flat supercontinuum generated by chalcogenide double-clad step-index fiber with special dispersion

To achave a broader supercontinuum in the mid-infrared band, a chalcogenide double-clad step-index fiber is proposed. Comprising As2Se3, AsSe2, and As2S5 glass, this fiber effectively confines light within the core, minimizing fiber dispersion fluctuations. By iteratively adjusting the dispersion curve of the fiber, enhancement of the supercontinuum spectrum generation is possible. Spectral broadening primarily results from four-wave mixing and self-phase modulation. Raman scattering within the pulse generates unstable higher-order solitons, which, upon breakup, contribute to spectrum broadening. This study explores the effects of pulse laser parameters and fiber length on supercontinuum generation, obtains regular cognition and offers theoretical analyses of the results. Through optimization of parameters, a mid-infrared supercontinuum with an 11 μm width is achieved. These findings underscore the potential of chalcogenide double-clad step-index fiber for generating a mid-infrared supercontinuum light source. The designed fiber structure should be helpful in supercontinuum sources, bio-molecule sensing, and spectroscopy.

Evolution of temporal fluctuation scaling exponent in nonstationary time series using supersymmetric theory of stochastic dynamics.

Temporal fluctuation scaling (TFS) is an emergent property of complex systems that relates the variance (Ξ_{2}) and the mean (M_{1}) from an empirical data set in the form Ξ_{2}∼M_{1}^{α_{TFS}}, where the dispersion (fluctuation) of the data has been described in terms of Ξ_{2}. At present, it has been shown that this law of complex systems has different multidisciplinary applications such as characterizing the market rate based on its exponent, explaining the spatial spread of a pandemic or measuring dispersion in a counting process, among others, if it is known how the average value M_{1} of a representative quantity in a system changes. Then, using the path integral formalism and Parisi-Sourlas method, we propose an extension of path integral formalism to understand the origin of the temporal fluctuation scaling and the evolution of its exponent over time in nonstationary time series. To this end, we first show how the probability of transition between two states of a stochastic variable x(t) can be expressed once it is known its cumulant generating function. Also, we introduce a nonlinear term in a cumulant generating function of the form H^{(n)}(p,t;γ)∼p^{n} to obtain a model where the nth moment of the probability distribution evolves arbitrarily. Subsequently, in order to reproduce the temporal fluctuation scaling, a linear combination of H^{(n)}(p,t;γ) with n∈{1,2} is used. Therefore this allows describing how the mean M_{1}(t) and the variance Ξ_{2}(t) of empirical time series evolve. Thence, an analytical expression is deduced for the evolution of the temporal evolution of the temporal fluctuation scaling exponent α_{TFS}(t). Likewise, the validity of the expression found for α_{TFS}(t) is verified with a toy model based on white noise. Finally, this approach is verified in two stock indices (Dow Jones and Sao Paulo stock index) and two currencies (GBP-USD and EUR-USD) with daily data. It is found that this approach accurately captures the evolution of the mean and variance of these four financial derivatives after contrasting the results with a coefficient of determination that depends on H^{(n)}(p,t;γ). Also, it is shown that the temporal fluctuation scaling exponent is a measure of uncertainty or volatility in financial time series.

Design and Characterization of Dispersion-Tailored Silicon Strip Waveguides toward Wideband Wavelength Conversion

One of cost-effective ways to increase the transmission capacity of current standard wavelength division multiplexing (WDM) transmission systems is to use a wavelength band other than the C-band to transmit in multi-band. We proposed the concept of multi-band system using wavelength conversion, which can simultaneously process signals over a wide wavelength range. All-optical wavelength conversion could be used to convert C-band WDM signals into other bands in a highly nonlinear fiber (HNLF) by four-wave mixing and allow to simultaneously transmit multiple WDM signals including other than the C-band, with only C-band transceivers. Wavelength conversion has been reported for various nonlinear waveguide materials other than HNLF. In such nonlinear materials, we noticed the possibility of wideband transmission by dispersion-tailored silicon-on-insulator (SOI) waveguides. Based on the CMOS process has high accuracy, it is expected that the chromatic dispersion fluctuation could be reduced in mass production. As a first step in the investigation of the broadness of wavelength conversion using SOI-based waveguides, we designed and fabricated dispersion-tailored 12 strip waveguides provided with an edge coupler at both ends. Each of the 12 waveguides having different widths and lengths and is connected to fibers via lensed fibers or by lenses. In order to characterize each waveguide, the pump-probe experimental setup was constructed using a tunable light source as pump and an unmodulated 96-ch C-band WDM test signal. Using this setup, we evaluate insertion loss, input power dependence, conversion bandwidth and conversion efficiency. We confirmed C-band test signal was converted to the S-band and the L-band using the same silicon waveguide with 3 dB conversion bandwidth over 100-nm. Furthermore, an increased design tolerance of at least 90 nm was confirmed for C-to-S conversion by shortening the waveguide length. It is confirmed that the wavelength converters using the nonlinear waveguide has sufficiently wide conversion bandwidth to enhance the multi-band WDM transmission system.

Non-Equilibrium Turbulent Transport in Convective Plumes Obtained from Closure Theory

The non-equilibrium property of turbulence modifies the characteristics of turbulent transport. With the aid of response function formalism, such non-equilibrium effects in turbulent transport can be represented by the temporal variation of the turbulent energy (K) and its dissipation rate (ε) along the mean stream through the advective derivatives of K and ε. Applications of this effect to the turbulent convection with plumes are considered for the first time in this work. The non-equilibrium transport effects associated with plumes are addressed in two aspects. Firstly, the effect associated with a single plume is evaluated using data measured in the recent plume/jet experiments. The second argument is developed for the collective turbulent transport associated with multiple plumes mimicking the stellar convection zone. In this second case, for the purpose of capturing the plume motions into the advective derivatives, use has to be made of the time–space double-averaging procedure, where the turbulent fluctuations are divided into the coherent or dispersion component (which represents plume motions) and the incoherent or random component. With the aid of the transport equations of the coherent velocity stress and the incoherent counterpart, the interaction between the dispersion and random fluctuations are also discussed in the context of convective turbulent flows with plumes. It is shown from these analyses that the non-equilibrium effect associated with plume motions is of a great deal of relevance in the convective turbulence modeling.

Predictability of passive scalar dispersion in atmospheric surface layers with urban‐like roughness: A large‐eddy simulations study

AbstractThe predictability of passive scalar dispersion is of both theoretical interest and practical importance, for example for high‐resolution numerical weather prediction and air quality modeling. However, the implications for the numerical modeling of urban areas remain relatively unexplored. Using obstacle‐resolving large‐eddy simulations (LES), we conducted twin experiments, with and without a velocity perturbation, to investigate how the presence of urban roughness affects error growth in streamwise velocity (u) and passive scalar (θ) fields, as well as the differences between error evolutions in u and θ fields. The predictability limit is characterized using the signal‐to‐noise ratio (SNR) as a continuous metric to indicate when error reaches saturation. The presence of urban roughness decreases of the passive scalar by around 20% compared to cases without them. The error statistics of θ indicate that urban roughness‐induced flow structures and different scalar source locations affect the scalar dispersion and relative fluctuations, which subsequently dictate the evolution of the SNR. Analysis of the passive scalar error energy (ϵθ2) budget indicates that the contributions from advective transport by the velocity and velocity error dominate. The error energy spectra of both u and θ exhibit a −5/3 slope in flat‐wall cases, but not in the presence of urban roughness, thereby highlighting the deviation from the assumption of locally isotropic turbulence. This study reveals that urban roughness can decrease the predictability of the passive scalar and destroy the similarity between the error statistics of the velocity and the passive scalar.

Analysis of particle dispersion in a turbulent flow considering particle rotation

Non-spherical particles exist widely in natural and industrial fluid systems and the motions of non-spherical particles are significantly different from that of spherical particles. In this paper, a simplified model of non-spherical particles considering particle drag correction, lift, and rotation was established. Based on the Eulerian–Lagrangian simulation, the dispersion characteristics of spherical and non-spherical particles with different Stokes numbers in a high-speed turbulent jet were analyzed and compared considering the effect of particle rotation. The results show that, the differences in particle dispersion and radial velocity fluctuation between non-spherical particles and spherical particles in the jet are significant, especially when Stokes number is large. Moreover, the effects of different type of forces on the dispersion of non-spherical particles and spherical particles were compared in detail, which revealed that the change of the Magnus force caused by the increase in the angular velocity of non-spherical particles plays a dominant role in the differences of particle dispersion.

A novel complexity-based mode feature representation for feature extraction of ship-radiated noise using VMD and slope entropy

To extract more distinguishing features of ships, slope entropy (SloE) is introduced into underwater acoustic signal processing as a new feature to analyze ship-radiated noise signal (S-NS) complexity. SloE can solve the defect that permutation entropy (PE) ignores the amplitude information of time series, and has not been employed to the field of underwater acoustics. On this basis, combined with the variational mode decomposition (VMD) algorithm, a feature extraction method of S-NS based on VMD and SloE is proposed. Firstly, S-NSs are collected by high-precision sensor, and the S-NS are decomposed into a series of the intrinsic mode functions by VMD. Then, the SloE of IMFs are extracted, and the recognition rate is calculated by k-nearest neighbor (KNN) algorithm. Finally, the comparison experiments with permutation entropy (PE), dispersion entropy (DE), reverse dispersion entropy (RDE) and fluctuation dispersion entropy (FDE) are carried out. The experimental results show that under the condition of single feature, SloE has the highest recognition rate; under the condition of multiple features, the feature extraction method based on SloE can attain higher recognition rate under the same number of features, and can realize the effective recognition of S-NSs.

Modelling stellar convective transport with plumes – I. Non-equilibrium turbulence effect in double-averaging formulation

ABSTRACT Plumes in a convective flow are considered to be relevant to the turbulent transport in convection. The effective mass, momentum, and heat transports in the convective turbulence are investigated in the framework of time–space double averaging procedure, where a field quantity is decomposed into three parts: the spatiotemporal mean (spatial average of the time-averaged) field, the dispersion or coherent fluctuation, and the random or incoherent fluctuation. With this framework, turbulent correlations in the mean-field equations are divided into the dispersion/coherent and random/incoherent correlation part. By reckoning the plume as the coherent fluctuation, a transport model for the convective turbulence is constructed with the aid of the non-equilibrium effect, in which the change of turbulence characteristics along the mean stream is taken into account for the modelling of the turbulent transport coefficients. In this work, for the first time, change of turbulence properties along plume motions is incorporated into the expression of the turbulent transport coefficients. This non-equilibrium model is applied to a stellar convective flow. One of the prominent characteristics of a surface cooling-driven convection, the enhanced and localized turbulent mass flux below the surface layer, which cannot be reproduced at all by the usual eddy-diffusivity model with mixing length theory (MLT), is well reproduced by the present model. Our results show that the incorporation of plume motion into turbulent transport model is an important and very relevant extension of mean-field theory beyond the heuristic gradient transport model with MLT.

Powder-flow behavior and process mechanism in laser directed energy deposition based on determined restitution coefficient from inverse modeling

In order to clarify the transportation mechanism of particles in continuous coaxial powder feeding (CCPF) process, a trial-and-matching method is developed to quantify the restitution coefficient which is used to describe the inelastic collision between the particle and the nozzle wall. The consistency of the outlet velocity and the spatial concentration distribution of particles between the experimental statistic and the numerical calculation shows that the restitution coefficient of 0.9 can be used to measure the inelastic collision behavior between particles and the nozzle wall. Employing the determined restitution coefficient, a semi-quantitative method based on optical diagnostic and quantitative analysis derived from numerical calculation are proposed to study the powder-gas flow transport characteristics from single-layer to multi-layer jet flow. It is found that the outer shielding gas flow (OSGF) has a great influence on the multi-layer jet flow field, and it is most conducive to powder focusing at the OSGF of 20 L/min. The velocity distribution of CGF determined by the inner structure of CCPFN and the inelastic collision between the particle and the wall are the two mutually coupled factors that determine the outlet velocity of particles. Frequent inelastic collisions and the decrease of the CGF velocity lead to velocity dispersion and trajectory fluctuation of particles. When the inlet velocity of particles is 1.33 m/s, the outlet velocity ranged from 0.4 m/s to 0.9 m/s. This paper aims to provide a general method to determine the restitution coefficient and offer a comprehensive understanding of transportation mechanism of power particles both inside continuous coaxial powder feeding nozzle (CCPFN) and multi-layer jet zone between substrate and the CCPFN outlet.

Two-pump parametric amplification in the presence of fiber dispersion fluctuations: a comparative study.

Fiber optical parametric amplifiers (FOPAs) operating based on four-wave mixing (FWM) are versatile devices with increasing applications in optical communication systems. In this paper, the effects of dispersion fluctuations on the performance of bandwidth, ripple, parametric gain, and saturation power of a two-pump FOPA based on four-wave and six-wave models are studied and compared. Coupled-amplitude equations representing the non-degenerate FWM process in optical fiber are solved numerically to compute the parametric gain over the communication wavelengths. The behaviors of the performance parameters are critically analyzed and compared with different types of fluctuation strengths (or amplitudes) specified by the combinations of correlation length (Lc) and fluctuation amplitude (σ). Based on the results, it was found that the flat gain bandwidth for the four-wave model remains unchanged and is insensitive to the strengths of fluctuations. The gain ripples, however, get higher as the fluctuation strengths increase. On the other hand, the flat gain bandwidths of the six-wave model are hardly identified due to the tremendous and continuous ripples within the pump wavelengths. In addition, the minimum parametric gain values for both four-wave and six-wave models reduce as the fluctuation strengths increase. Also, the lowest value of parametric gain leads to the highest saturation power and vice versa. The dispersion fluctuations affect the FWM process's efficiency and deteriorate the overall amplifier performance, particularly for the six-wave model. The numerical analysis obtained via the six-wave model is especially useful since this model closely matches with practical circumstances.

Hybrid Forecasting Methodology for Wind Power-Photovoltaic-Concentrating Solar Power Generation Clustered Renewable Energy Systems

Forecasting of large-scale renewable energy clusters composed of wind power generation, photovoltaic and concentrating solar power (CSP) generation encounters complex uncertainties due to spatial scale dispersion and time scale random fluctuation. In response to this, a short-term forecasting method is proposed to improve the hybrid forecasting accuracy of multiple generation types in the same region. It is formed through training the long short-term memory (LSTM) network using spatial panel data. Historical power data and meteorological data for CSP plant, wind farm and photovoltaic (PV) plant are included in the dataset. Based on the data set, the correlation between these three types of power generation is proved by Pearson coefficient, and the feasibility of improving the forecasting ability through the hybrid renewable energy clusters is analyzed. Moreover, cases study indicates that the uncertainty of renewable energy cluster power tends to weaken due to partial controllability of CSP generation. Compared with the traditional prediction method, the hybrid prediction method has better prediction accuracy in the real case of renewable energy cluster in Northwest China.

Microscopic theory of plasmon-enabled resonant terahertz detection in bilayer graphene

The electron gas hosted in a two-dimensional solid-state matrix, such as a quantum well or a two-dimensional van der Waals heterostructure, supports the propagation of plasma waves. Nonlinear interactions between plasma waves, due to charge conservation and current convection, generate a constant density gradient which can be detected as a dc potential signal at the boundaries of the system. This phenomenon is at the heart of a plasma-wave photodetection scheme which was first introduced by Dyakonov and Shur for electronic systems with a parabolic dispersion and then extended to the massless Dirac fermions in graphene. In this work, we develop the theory of plasma-wave photodetection in bilayer graphene, which has the peculiarity that the dispersion relation depends locally and dynamically on the intensity of the plasma wave. In our analysis, we show how quantum capacitance effects, arising from the local fluctuations of the electronic dispersion, modify the intensity of the photodetection signal. An external electrical bias, e.g. induced by top and bottom gates, can be used to control the strength of the quantum capacitance corrections, and thus the photoresponse.

Gain-saturated two-pump fiber optical parametric amplifiers in the presence of dispersion fluctuation and fourth-order dispersion coefficient

The saturated gain performance of the two-pump fiber optical parametric amplifier (2-P FOPA) in the presence of random dispersion fluctuation as well as fourth-order dispersion coefficient are investigated. The gain spectra of the 2-P FOPA is simulated by solving the coupled equations numerically, considering the dispersion fluctuations along the fiber as a stochastic process with a given standard deviation and correlation length. The gain performance of 2-P FOPA is analysed with the variation of correlation length, standard deviation and fourth-order dispersion coefficient, respectively. It shows that, the gain saturation curves of 2-P FOPA exhibit obvious differences in the presence of dispersion fluctuations and fourth-order dispersion coefficients. The peak gain reduces with the increase of the standard deviation and the reduction is higher in case of shorter correlation lengths, also the variations of 2-P FOPA saturation powers are affected by the standard deviation and correlation length significantly. In addition, the performance of the 2-P FOPA varies greatly while considering the fourth-order dispersion coefficient, where the peak gain remains the same, but the 3 dB bandwidth is wider with considering the fourth-order dispersion coefficient. The numerical analysis is meaningful for the research of 2-P FOPA saturated gain performance, which having attracted great research interests in the optical fiber communication systems.

Higher Order Statistics of Parametric Amplifier Gain Variation Due to Dispersion Fluctuation

Currently, there are no analytical formulas or ordinary differential equations (ODEs) to investigate the higher order statistics for the gain variations in fiber parametric amplifiers (FOPAs) with dispersion fluctuation. This is mainly due to the tedious efforts to derive the related ODEs. In this article, a comprehensive generalized stochastic coupled mode equation approach for the ODE derivation is proposed to study the gain variations in FOPAs, which greatly simplifies the derivation process. Based on the systematic approach, one may find the higher order statistics of the FOPA gain without the time consuming Monte Carlo simulations. The analytical and numerical solutions of the ODEs agree well with the Monte Carlo simulations. The approach can be extended to other practical problems like the higher order statistics of the mode amplitudes in the multimode fibers with random coupling.

On the Convergence and Capability of the Large-Eddy Simulation of Concentration Fluctuations in Passive Plumes for a Neutral Boundary Layer at Infinite Reynolds Number

Large-eddy simulation (LES) experiments have been performed using the Parallelized LES Model (PALM). A methodology for validating and understanding LES results for plume dispersion and concentration fluctuations in an atmospheric-like flow is presented. A wide range of grid resolutions is shown to be necessary for investigating the convergence of statistical characteristics of velocity and scalar fields. For the scalar, the statistical moments up to the fourth order and the shape of the concentration probability density function (p.d.f.) are examined. The mean concentration is influenced by grid resolution, with the highest resolution simulation showing a lower mean concentration, linked to larger turbulent structures. However, a clear tendency to convergence of the concentration variance is observed at the two higher resolutions. This behaviour is explained by showing that the mechanisms driving the mean and the variance are differently influenced by the grid resolution. The analysis of skewness and kurtosis allows also the obtaining of general results on plume concentration fluctuations. Irrespective of grid resolution, a family of Gamma p.d.f.s well represents the shape of the concentration p.d.f. but only beyond the peak of the concentration fluctuation intensity. In the early plume dispersion phases, the moments of the p.d.f. are in good agreement with those generated by a fluctuating plume model. To the best of our knowledge, our study demonstrates for the first time that, if resolution and averaging time are adequate, atmospheric LES provides a trustworthy representation of the high order moments of the concentration field, up to the fourth order, for a dispersing plume.

Turbulent flows over dense filament canopies

Turbulent flows over dense canopies of rigid filaments of small size are investigated for different element heights and spacings using DNS. The flow can be decomposed into the element-coherent, dispersive flow, the Kelvin--Helmholtz-like rollers typically reported over dense canopies, and the background, incoherent turbulence. The canopies studied have spacings $s^+ = 3$--$50$, which essentially preclude the background turbulence from penetrating within. The dispersive velocity fluctuations are also mainly determined by the spacing, and are small deep within the canopy, where the footprint of the Kelvin--Helmholtz-like rollers dominates. Their typical streamwise wavelength is determined by the mixing length, which is essentially the sum of its height above and below the canopy tips. For the present dense canopies, the former remains roughly the same in wall-units, and the latter, which scales with the drag length, depends linearly on the spacing. This is the result of the drag being essentially viscous and governed by the planar layout of the canopy. In shallow canopies, the proximity of the canopy floor inhibits the formation of Kelvin--Helmholtz-like rollers, with essentially no signature for height-to-spacing ratios $h/s \approx 1$, and no further inhibition beyond $h/s \approx 6$. Very small spacings also inhibit the rollers, due to their obstruction by the canopy elements. The obstruction decreases with increasing spacing and the signature of the instability intensifies, even if for canopies sparser than those studied here the instability eventually breaks down. Simple models based on linear stability can capture some of the above effects.

Impact of Random Dispersion Fluctuations on Two-Pump Fiber Optical Parametric Amplifier Performances

The impact of random dispersion fluctuations on two-pump (2-P) fiber optical parametric amplifier (FOPA) performance in terms of parametric gain, 3-dB amplification bandwidth and saturation power is numerically investigated. The four-coupled amplitude equations which represent the parametric process in optical fiber are solved using the Runge-Kutta method. Based on the results, it was observed that the random dispersion fluctuations reduced the parametric gain, increased the saturation power and had no significant effect on 3-dB amplification bandwidth. The resulted behaviors are mainly due to the changes of phase-matching condition in optical fiber. All in all, the random dispersion fluctuations are potentially limited the 2-P FOPA performances.

Endogenous second moments: A unified approach to fluctuations in risk, dispersion, and uncertainty

We explore a mechanism by which second moments—such as cross-sectional dispersions, risk, volatility, or uncertainty—naturally and endogenously fluctuate over time as nonlinear transformations of fundamentals. Specifically, we provide theoretical results that characterize second moments of transformed random variables when the underlying fundamentals are subject to distributional shifts that affect their means, but not their variances. We illustrate the usefulness of our results with a series of applications. Our main application concerns the cross-sectional dispersions of output, employment, and Solow residuals, which we show to become countercyclical if employment and capital are gross complements. The mechanism can account for a significant share of the empirical cyclicality patterns, without exogenous shocks to volatilities. In additional applications we use our theory to study endogenous fluctuations in the dispersion of MRPKs, in risk in security pricing, and in uncertainty in Bayesian inference problems.

Precursors signatures of few major earthquakes in Italy using very low frequency signal of 45.9 kHz

On May 20 and May 29, 2012, earthquakes of magnitude MW 6.1 and 5.8, respectively, struck Emilia-Romagna of Italy. We present the results obtained from the US Navy VLF Transmitter’s NSY signal of 45.9 kHz transmitted from Niscemi, in the province of Sicily, Italy, and received at the Kiel Longwave Monitor, Germany, for 2012. We analyzed the terminator times, D-layer preparation and disappearance times and nighttime fluctuation parameters. We also analyzed trends, dispersion and nighttime fluctuation which gave us possible precursors to these earthquakes. Possible perturbations due to other factors were filtered. Moreover, the findings of these two earthquakes were compared to Central Italy EQ on August 24, 2016, and Tuscany EQ on June 21, 2013. Therefore, this manuscript is the overall analysis of four earthquakes, out of which two were already published before. As our TRGCP path is North–South, the sunrise and sunset times in transmitter and receiver places match making a pathway for VLF/LF smoother and therefore hoping to obtain more natural data. We found many clear anomalies (as precursors) in terminator times 5 days to 16 days before the earthquakes. Moreover, using nighttime fluctuation method, we found clear anomalies 5–13 days prior to main earthquakes. This exactly correlates with the findings of previous authors that ionospheric perturbations are seen from few days to few weeks before the seismic activity. In addition to this, we observed an unexpected decrease in dispersion on certain anomalies where it was supposed to increase, thereby not supporting our finding to some extent. To resolve this problem, we devised a new parameter called dispersion nighttime (dispersion*). On analyzing, this parameter decreases significantly on days of nighttime anomalies, thereby supporting our precursors to much extent.

Pre-processing of Photoplethysmographic Waveform for Amplitude Regularization

This study is aimed to develop a post-processing method to regularize amplitude of PPG waveforms and evaluate the performance of the algorithm. The proposed procedure for regularizing amplitude consists of extracting the signal envelopes based on time-domain filtering, generating a compensation curve, and reconstructing the waveform. The proposed technique was evaluated with respect to dispersion and waveform fluctuation by means of coefficients of variation (CV) and a scaling exponent of detrended fluctuation analysis (DFA). Other criteria included the detection performances of major features such as upper and lower fiducial points and maximum dV/dt. In developing this method, we used a clinical dataset that comprised 74,225 beats. By applying reconstruction algorithm, the %CV and the scaling exponent of DFA were significantly decreased from 115.4 to 71.4 and from 1.029 to 0.836, respectively in peak amplitude. In valley amplitude, they were also decreased from 38.3 to 13.2 and from 0.993 to 0.713, respectively. Moreover, sensitivity of maximum dV/dt point, upper and lower peak detection are increased by 8.50, 2.72 and 5.21% after reconstruction, respectively. Our results clearly showed that the proposed reconstruction technique could reduce amplitude fluctuation and improve detection of fiducial points.