scholarly journals Forensic Speaker Comparison Using Evidence Interval in Full Bayesian Significance Test

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Adelino P. Silva ◽  
Maurílio N. Vieira ◽  
Adriano V. Barbosa
Keyword(s):  
Monte Carlo ◽  
Markov Chains ◽  
Signal To Noise Ratio ◽  
Significance Test ◽  
Signal To Noise ◽  
Interval Size ◽  
Unknown Variance ◽  
Classification Errors ◽  
Expected Values ◽  
Noise Ratio

This paper describes the application of a full Bayesian significance test (FBST) to compute evidence intervals in forensic speaker comparison (FSC). In the FBST approach, the challenge is to apply the test to a large number of observations and to formulate an equation to solve the test quickly. The contribution of the present work is that it proposes an application of the FBST to FSC and develops a method to calculate the FBST for the distribution of expected values (mean) with unknown variance without using Monte Carlo Markov chains (MCMC). Comparisons with other interval inference methodologies indicate that the evidence interval size is 49% greater than that computed with the Gosset approach. The evidence interval presented 71% fewer classification errors than the punctual inference did for the signal-to-noise ratio (SNR) of 17 dB.

Picking noisy refraction data using semblance supplemented by a Monte Carlo procedure and spectral balancing

1987 ◽  
Vol 77 (3) ◽  
pp. 942-957
Author(s):  
C. A. Zelt ◽  
J. J. Drew ◽  
M. J. Yedlin ◽  
R. M. Ellis
Keyword(s):  
Monte Carlo ◽  
Cross Correlation ◽  
Signal To Noise Ratio ◽  
Time Shift ◽  
Head Wave ◽  
Signal To Noise ◽  
Seismic Section ◽  
Monte Carlo Procedure ◽  
Noise Ratio ◽  
Refraction Data

Abstract In crustal refraction experiments, the crucial deeply refracted and head wave arrivals often have a low signal-to-noise ratio. A method to aid in the picking of noisy refraction data is presented which is applicable to any branch of a seismic section whose waveform is approximately invariant throughout the branch. The technique exploits the spatial correlation of arrivals and is based on the lateral coherency which results if the refracted arrivals are aligned by applying appropriate time shifts to each trace of the branch. The alignment of arrivals occurs iteratively and is accomplished through a cross-correlation of each trace with the stack of the section of the previous iteration. The iteration yielding the section with the highest degree of lateral coherency (semblance) is used to extract the travel-time pick of each trace. The pick, plus a possible d.c. component, is the negative of the time shift required to achieve arrival alignment. Two modifications can improve the performance of the picking routine. To prevent a cycle skipping problem, a Monte Carlo technique is implemented in which the cross-correlation function is transformed into a probability distribution so that the lag corresponding to the maximum cross-correlation is most probably selected. Second, to increase the coherency of the arrivals, a spectral balancing technique is applied in either the time or frequency domain. The picking routine is applied to both a synthetic and real data example, and the results suggest that the routine can be applied successfully to data with a signal-to-noise ratio as low as one. Also, the Monte Carlo procedure together with spectral balancing increases the final semblance over that obtained with the unmodified method.

scholarly journals Procedure to optimize the intercarrier spacing in superchannels impaired by the cascading of WSS-based ROADMs

2020 ◽  
Vol 238 ◽  
pp. 09001
Author(s):  
Paulo J. Pereira ◽  
João L. Rebola ◽  
Luís G. Cancela
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Signal To Noise Ratio ◽  
Optical Signal ◽  
Signal To Noise ◽  
Optical Filtering ◽  
Noise Ratio ◽  
Wavelength Selective Switch

A new procedure is proposed to optimize the intercarrier spacing and wavelength selective switch (WSS) bandwidth for superchannels, using a Monte Carlo simulation. We perform an exhaustive assessment of the optical signal-to-noise ratio (OSNR) penalties due to the optical filtering and intercarrier crosstalk, and concluded that the optimum intercarrier spacing is at most 1.1 GHz larger than the Nyquist bandwidth and the results show how the number of cascaded WSSs influences the intercarrier spacing.

scholarly journals Evaluation of Nonlinear Interference Effects in a Dispersion Managed (DM) Optical Fiber: Performance and Transmission Analysis of 16QAM Modulation using Split Step Fourier Method

2020 ◽  
Author(s):  
Reinhardt Rading
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Optical Fiber ◽  
Signal To Noise Ratio ◽  
Fourier Method ◽  
Interference Effects ◽  
Signal To Noise ◽  
Optical Links ◽  
Noise Ratio ◽  
The Impact

<div>This paper investigates the impact on the optical</div><div>signal-to-noise ratio (OSNR) of the residual per span (RDPS) in a N × 100km dispersion managed system with zero total accumulated dispersion from input to output using split step Fourier method (SSFM) -Monte Carlo simulation. </div><div><br></div><div>This paper shows that the nonlinear interference NLI does in-fact impact the performance yielding different best working power depending on the value of Nx100 km span and the type of dispersion managed link. The paper shows that dispersion uncompensated optical links are preferable to dispersion managed fibers in equalizing NLI effects in long haul optical links.</div>

scholarly journals Monte Carlo simulation of neutron scattering by a textured polycrystal

2020 ◽  
Vol 53 (2) ◽  
pp. 512-529 ◽  
Author(s):  
Victor Laliena ◽  
Miguel Ángel Vicente-Álvarez ◽  
Javier Campo
Keyword(s):  
Monte Carlo ◽  
Neutron Scattering ◽  
Signal To Noise Ratio ◽  
Orientation Distribution ◽  
Pressure Tube ◽  
Monte Carlo Code ◽  
Signal To Noise ◽  
Transmission Experiment ◽  
Pressure Cell ◽  
Noise Ratio

A method of simulating the neutron scattering by a textured polycrystal is presented. It is based on an expansion of the scattering cross sections in terms of the spherical harmonics of the incident and scattering directions, which is derived from the generalized Fourier expansion of the polycrystal orientation distribution function. The method has been implemented in a Monte Carlo code as a component of the McStas software package, and it has been validated by computing some pole figures of a Zircaloy-4 plate and a Zr–2.5Nb pressure tube, and by simulating an ideal transmission experiment. The code can be used to estimate the background generated by components of neutron instruments such as pressure cells, whose walls are made of alloys with significant crystallographic texture. As a first application, the effect of texture on the signal-to-noise ratio was studied in a simple model of a diffraction experiment, in which a sample is placed inside a pressure cell made of a zirconium alloy. With this setting, the results of two simulations were compared: one in which the pressure-cell wall has a uniform distribution of grain orientations, and another in which the pressure cell has the texture of a Zr–2.5Nb pressure tube. The results showed that the effect of the texture of the pressure cell on the noise of a diffractogram is very important. Thus, the signal-to-noise ratio can be controlled by appropriate choice of the texture of the pressure-cell walls.

scholarly journals Analysis of Individual Positron Emission Tomography Activation Maps by Detection of High Signal-to-Noise-Ratio Pixel Clusters

1993 ◽  
Vol 13 (3) ◽  
pp. 425-437 ◽  
Author(s):  
Jean-Baptiste Poline ◽  
Bernard M. Mazoyer
Keyword(s):  
Positron Emission Tomography ◽  
Monte Carlo ◽  
Signal To Noise Ratio ◽  
New Method ◽  
Emission Tomography ◽  
High Signal ◽  
Type I ◽  
Signal To Noise ◽  
Positron Emission ◽  
Noise Ratio

We present a new method for the analysis of individual brain positron emission tomography (PET) activation maps that looks for activated areas of a certain size rather than pixels with maximum values. High signal-to-noise-ratio pixel clusters (HSC) are identified and their sizes are statistically tested with respect to a Monte-Carlo–derived distribution of cluster sizes in pure noise images. From multiple HSC size tests, a strategy is proposed for control of the overall type I error. The sensitivity and specificity of this method have been assessed using realistic Monte Carlo simulations of brain activation maps. When compared with the γ2 statistic of the local maxima distribution, the proposed method showed enhanced sensitivity, particularly for signals of low magnitude and/or large size. Its potential for the individual analysis of PET activation studies is presented in two sets of subjects who underwent two cognitive protocols. Although it can be viewed as an alternative to the classical stereotactic averaging approach, this new method is intended to be a first step toward the analysis of single-subject PET activation studies.

AN IMPROVED PULSE TRANSIENT AIRBORNE ELECTROMAGNETIC SYSTEM FOR LOCATING GOOD CONDUCTORS

Geophysics ◽  
1976 ◽  
Vol 41 (2) ◽  
pp. 287-299 ◽  
Author(s):  
D. Gupta Sarma ◽  
V. M. Maru ◽  
G. Varadarajan
Keyword(s):  
Comparative Study ◽  
Time Constant ◽  
Decay Time ◽  
Signal To Noise Ratio ◽  
Transient Field ◽  
Signal To Noise ◽  
Electromagnetic System ◽  
Airborne Electromagnetic ◽  
Expected Values ◽  
Noise Ratio

Measuring the transient field values (H), rather than their time derivatives (dH/dt), with an inductive, pulse‐excited electromagnetic prospecting system makes the device capable of reducing much of the geologic noise due to poor superficial conductors and enhancing the response from good conductors. The factor of improvement in signal‐to‐geologic noise ratio in H measurement may be as much as [Formula: see text], where [Formula: see text], and [Formula: see text] are the expected values of decay time constant of signal and noise components, respectively. Moreover, signal‐to‐noise ratio increases for later sample channels, thus allowing equal gate timings for all sample channels. Field results of a comparative study with H and dH/dt measurements are shown. It is predicted that both depth of exploration and reliability of interpretation of data in quantitative terms may improve somewhat with such a system.

scholarly journals A GATE Monte Carlo model for a newly developed small animal PET scanner: the IRI-microPET

2019 ◽  
Vol 25 (2) ◽  
pp. 93-100
Author(s):  
S.Z. Islami Rad ◽  
R. Gholipour Peyvandi ◽  
M.K. Sadeghi
Keyword(s):  
Monte Carlo ◽  
System Performance ◽  
Signal To Noise Ratio ◽  
Monte Carlo Model ◽  
System Optimization ◽  
Small Animal Pet ◽  
Monte Carlo Code ◽  
Signal To Noise ◽  
Animal Pet ◽  
Noise Ratio

Abstract Monte Carlo simulation is widely used in emission tomography, in order to assess image reconstruction algorithms and correction techniques, for system optimization, and study the parameters affecting the system performance. In the current study, the performance of the IRI-microPET system was simulated using the GATE Monte Carlo code and a number of performance parameters, including spatial resolution, scatter fraction, sensitivity, RMS contrast, and signal-to-noise ratio, evaluated and compared to the corresponding measured values. The results showed an excellent agreement between simulated and measured data: The experimental and simulated spatial resolutions (radial) for 18F in the center of the AFOV were 1.81 mm and 1.65 mm, respectively. The difference between the experimental and simulated sensitivities of the system was <7%. Simulated and experimental scatter fractions differed less than 9% for the mouse phantom in different timing windows. The validation study of the image quality indicated a good agreement in RMS contrast and signal-to-noise ratio. Also, system performance was compared with the two available commercial scanners which were simulated using GATE code. In conclusion, the assessment of the Monte Carlo modeling of the IRI-microPET system reveals that the GATE code is a flexible and accurate tool for describing the response of an animal PET system.

scholarly journals Quantitative Evaluation of Phase Distribution in UHMWPE as Derived from a Combined Use of NMR FID Analysis and Monte Carlo Simulation

2021 ◽  
Author(s):  
Eddy Hansen ◽  
Alireza Hassani
Keyword(s):  
Monte Carlo ◽  
Phase Distribution ◽  
Signal To Noise Ratio ◽  
Critical Evaluation ◽  
Model Fitting ◽  
Signal To Noise ◽  
Combined Use ◽  
Reliable Parameter ◽  
Free Induction ◽  
Noise Ratio

AbstractA new and robust statistical approach is explored with the objective to derive quantitative and reliable information on the molecular dynamics within distinct domains (crystalline, intermediate and amorphous domains) of ultra-high molecular weight polyethylene (UHMWPE). The method consists of a critical evaluation of the free induction decay (FID) model, which is used to generate synthetic FID with a predefined signal-to-noise ratio by Monte Carlo simulations. The application of the method is demonstrated for three UHMWPE samples. A subsequent model fitting of their synthetic FIDs revealed a unique correlation between the error, i.e., standard deviation, of the derived parameters and the FID signal-to-noise ratio (SNRFID). Moreover, it was found that the method can be used to estimate the minimum required sampling time to obtain reliable parameter estimation of the FID model to experimental data.

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