scholarly journals Speckle patterns formed by broadband terahertz radiation and their applications for ghost imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lev Leibov ◽  
Azat Ismagilov ◽  
Victor Zalipaev ◽  
Boris Nasedkin ◽  
Yaroslav Grachev ◽  
...  
Keyword(s):  
Correlation Length ◽  
Imaging Technique ◽  
Strong Dependence ◽  
Thz Radiation ◽  
Ghost Imaging ◽  
Statistical Parameters ◽  
Speckle Patterns ◽  
Speckle Size ◽  
The Mean ◽  
Phase Surface

AbstractSpeckle patterns can be very promising for many applications due to their unique properties. This paper presents the possibility of numerically and experimentally formation of speckle patterns using broadband THz radiation. Strong dependence of the statistical parameters of speckles, such as size and sharpness on the parameters of the diffuser are demonstrated: the correlation length and the mean square deviation of the phase surface inhomogeneity. As the surface correlation length is increasing, the speckle size also increases and its sharpness goes down. Alternatively, the magnification of the standard deviation of the surface height leads to the speckle size diminishing and growth of the speckle sharpness. The dimensions of the experimentally formed speckles correspond to the results of numerical simulation. The possibility of utilizing formed speckle patterns for the implementation of the ghost imaging technique has been demonstrated by methods of numerical modeling.

scholarly journals Speckle Patterns formed by Broadband Terahertz Radiation and their Applications for Ghost Imaging

2021 ◽  
Author(s):  
Lev Leibov ◽  
Azat Ismagilov ◽  
Victor Zalipaev ◽  
Boris Nasedkin ◽  
Yaroslav Grachev ◽  
...  
Keyword(s):  
Correlation Length ◽  
Strong Dependence ◽  
Thz Radiation ◽  
Ghost Imaging ◽  
Statistical Parameters ◽  
Speckle Patterns ◽  
Speckle Size ◽  
The Mean ◽  
Phase Surface ◽  
The Individual

Abstract Speckle patterns can be very promising for some applications due to their unique properties. This paper presents the possibility of numerically and experimentally formation of speckle patterns using broadband THz radiation. Strong dependence of the statistical parameters of speckles, such as size and sharpness on the parameters of the diffuser are demonstrated: the correlation length and the mean square deviation of the phase surface inhomogeneity. As the surface correlation length increasing, the speckle size increases and its sharpness decreases. Alternatively, increasing of the surface height standard deviation leads to a speckle size decreasing and sharpness increasing. The dimensions of the individual experimentally formed speckles correspond to obtained results of numerical simulation. The possibility of the formed speckle patterns application for the implementation of the ghost imaging technique has been demonstrated by methods of numerical modeling.

Statistical Speckle Study of Copper Nanofluids

2009 ◽  
Author(s):  
Nastaran Mansour ◽  
Mehdi Mohammad Kazemi ◽  
Rouhollah Karimzadeh ◽  
Javid Zamir Anvari
Keyword(s):  
Brownian Motion ◽  
Statistical Analysis ◽  
Continuous Wave ◽  
Pure Copper ◽  
Stochastic Approach ◽  
Statistical Parameters ◽  
Copper Target ◽  
Nanosecond Pulsed Laser ◽  
Speckle Patterns ◽  
Speckle Size

We report on a statistical analysis of copper nanofluid speckle image patterns. The far-field speckle images are formed by illuminating the copper nanoparticle (CuNP) suspension using low power continuous wave laser light at 532 nm. The nanofluids is prepared by nanosecond pulsed laser ablation of the highly pure copper target in polysiloxane oil. A stochastic approach based on the fractional Brownian motion and the classical frequential method is applied on the speckle patterns. These methods enable us to extract statistical parameters such as mean speckle size, Hurst coefficient and saturation of variance. Our results show that the mean speckle size remains unchanged with respect to time while the Hurst exponent and the saturation of variance exhibit changes. It has been shown that the stochastic approach makes it possible to characterize the copper nanofluid. The statistical analysis indicates that the Brownian motion of nanoparticles play important role in thermal properties of the copper nanofluids. Including the Brownian motion, the thermal conductivity of the copper nanofluids is calculated.

scholarly journals Methods for Determination of Mean Speckle Size in Simulated Speckle Pattern

2014 ◽  
Vol 14 (3) ◽  
pp. 177-182 ◽  
Author(s):  
I. Hamarová ◽  
P. Šmíd ◽  
P. Horváth ◽  
M. Hrabovský
Keyword(s):  
Gaussian Beam ◽  
Speckle Pattern ◽  
Two Dimensional ◽  
One Dimensional ◽  
Theoretical Predictions ◽  
Speckle Patterns ◽  
Speckle Size ◽  
The Mean ◽  
The One

Abstract This paper deals with computation of mean speckle size in a speckle pattern generated through a numerical simulation of speckle after reflection of a Gaussian beam off a rough object’s surface. Within this simulation various speckle patterns are obtained by means of change in a parameter of the Gaussian beam. The mean speckle size is computed through two approaches using both the two-dimensional and the one-dimensional normalized autocorrelation function in intensity. Additionally, we propose a distinct optimization of the determination of the mean speckle size by reduction of intensity values representing detected speckle patterns. Results of the determination of the mean speckle size are compared with theoretical predictions

scholarly journals Fourier transforms for fast and quantitative Laser Speckle Imaging

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
J. Buijs ◽  
J. van der Gucht ◽  
J. Sprakel
Keyword(s):  
Quantitative Data ◽  
Fourier Transforms ◽  
Imaging Technique ◽  
Laser Speckle ◽  
Frequency Range ◽  
Laser Speckle Imaging ◽  
Speckle Imaging ◽  
New Approach ◽  
Speckle Patterns ◽  
New Processing

Abstract Laser speckle imaging is a powerful imaging technique that visualizes microscopic motion within turbid materials. At current two methods are widely used to analyze speckle data: one is fast but qualitative, the other quantitative but computationally expensive. We have developed a new processing algorithm based on the fast Fourier transform, which converts raw speckle patterns into maps of microscopic motion and is both fast and quantitative, providing a dynamnic spectrum of the material over a frequency range spanning several decades. In this article we show how to apply this algorithm and how to measure a diffusion coefficient with it. We show that this method is quantitative and several orders of magnitude faster than the existing quantitative method. Finally we harness the potential of this new approach by constructing a portable laser speckle imaging setup that performs quantitative data processing in real-time on a tablet.

scholarly journals BatScope manages acoustic recordings, analyses calls, and classifies bat species automatically

2018 ◽  
Vol 96 (9) ◽  
pp. 939-954 ◽  
Author(s):  
M.K. Obrist ◽  
R. Boesch
Keyword(s):  
High Frequency ◽  
Reference Database ◽  
Correct Classification Rate ◽  
Statistical Parameters ◽  
Classification Rate ◽  
Echolocation Calls ◽  
Portable Software ◽  
Automated Processing ◽  
The Mean ◽  
Species Assignment

BatScope is a free application for processing acoustic high-frequency recordings of bats. It can import data, including meta-data information, from recorders such as Batlogger. The resulting content can be filtered visually as spectrograms or according to data fields and can be displayed. Automated processing includes detecting and extracting of echolocation calls, filtering noise, and measuring statistical parameters. Calls are classified to species by statistically matching to a reference database. A weighted list of classifiers helps to assign the most likely species per call. Classifiers were trained on 19 636 echolocation calls of 27 European bat species. When classifiers all agree on a species (76.4% of all cases), the mean correct classification rate reaches 95.7%. A sequence’s summary statistic indicates the most likely species occurring therein. Classifications can be verified visually, by filtering, and by acoustic comparison with reference calls. Procedures are available for, e.g., excluding dubious cutouts from the statistics and for accepting or overriding the proposed species assignment. Acoustic recordings can be exported and exchanged with other users. Finally, the verified results can be exported to spreadsheets for further analyses and reporting. We currently reprogram BatScope using Java, PostgreSQL, and R to reach a unified and portable software architecture.

Mathematical-Statistical Methods for the Analysis of Aerial Triangulation Adjustment Errors Using a Computer Program

1975 ◽  
Vol 29 (2) ◽  
pp. 175-188
Author(s):  
M. Mosaad Allam
Keyword(s):  
Computer Program ◽  
Frequency Interval ◽  
Mean Square ◽  
Fisher Criterion ◽  
Statistical Parameters ◽  
Sample Distribution ◽  
Development Section ◽  
The Mean ◽  
Kolmogorov Criterion ◽  
Mean Square Errors

In practice, photogrammetrists use a single statistic reliability interval criterion, based on the mean square errors, to judge the accuracy of adjustment of photogrammetric blocks. Even in some cases, if the practical and theoretical distributions of frequency interval agree, such a test does not make it possible to establish the closeness of their convergence nor the degree of their difference. In other words, to get a complete picture of the character of the distribution of errors in the adjusted photogrammetric blocks, it is insufficient to investigate any single statistic. In the Research and Development Section of the Topographical Survey Directorate, a computer program (SABA) has been designed to analyze the errors of photogrammetric block adjustments, compute various statistical parameters and check the sample distribution using Kolmogorov criterion. Based on the decision taken, the correspondence between the empirical and theoretical distribution series are checked using the criterion χ2. The program divides the adjusted block to make a comparative evaluation of accuracies in the different sub-blocks. In this case, in addition to Kolmogorov and χ2 tests, the program checks the reliability intervals of the means and mean square errors of the samples and uses Fisher criterion ‘F’ to check the hypothesis of the equality of dispersion. SABA is coded in Fortran IV and Compass for the CDC CYBER 74 and requires a central memory of 28K decimal works. SABA is the acronym for Statistical Analysis of Block Adjustment.

Using digital photogrammetry to monitor soil erosion under conditions of simulated rainfall and wind

Soil Research ◽  
2010 ◽  
Vol 48 (1) ◽  
pp. 36 ◽  
Author(s):  
S. Moritani ◽  
T. Yamamoto ◽  
H. Andry ◽  
M. Inoue ◽  
T. Kaneuchi
Keyword(s):  
Soil Erosion ◽  
Soil Surface ◽  
Specific Area ◽  
Algorithm Analysis ◽  
Simulated Rainfall ◽  
Digital Photogrammetry ◽  
Statistical Parameters ◽  
Surface Evolution ◽  
The Mean ◽  
Sheet Erosion

We investigated a method to measure sheet erosion by characterising the soil erosion of an upland field in a dryland environment. Digital photogrammetry was used to measure the erosion rates of soil surfaces packed to different densities under simulated rainfall or wind conditions. The photogrammetry system consisted of 2 digital cameras, a rainfall simulator, a wind tunnel, and a computer program for 3-dimensional algorithm analysis. First, we assessed the accuracy of our method by comparing conventionally measured data to photogrammetric data under conditions of either no rainfall or no wind application. Two statistical parameters were used to evaluate the soil surface evolution: the mean absolute error (MAE) and the mean relative error (MRE). Their values were 0.21 mm and 15.8%, respectively. We then assessed the precision of our system under simulated rainfall conditions using 3 different dry bulk densities for the packed saturated soil surface. At densities of 0.91, 0.98, and 1.09 g/cm3, the MAE (MRE) values were 2.21 mm (392.5%), 1.07 mm (126.4%), and 0.59 mm (57.6%), respectively. It was possible to monitor and evaluate both the amount of eroded soil and the erosion mechanism in a specific area. Moreover, this system could be applied to measuring wind erosion with an MAE accuracy as high as 0.21 mm. The digital elevation models (DEMs) allowed for detailed analyses of soil surface evolution, and it was also possible to monitor sheet erosion with high spatial and temporal resolutions.

Evidence for Yield Stability in Selected Landraces of Bean (Phaseolus vulgaris)

1988 ◽  
Vol 24 (3) ◽  
pp. 367-373 ◽  
Author(s):  
Eric Ayeh
Keyword(s):  
Phaseolus Vulgaris ◽  
Linear Relationship ◽  
Standard Error ◽  
Yield Stability ◽  
Synthetic Mixture ◽  
Heterozygote Advantage ◽  
Statistical Parameters ◽  
Genotype X Environment ◽  
The Mean

SUMMARYYield stability in beans from diverse sources in Malawi was estimated using the statistical parameters of genotype X environment variance, slope and standard error from regression. The heterozygous F2 and the most complex synthetic mixture were very stable, although not significantly different from some pure genotypes. The mean yields of most mixtures were marginally higher than the average of their components. There was a linear relationship between magnitude of diversity and stability. Evidence for heterozygote advantage was demonstrated.

Velocities of Starch Particles in ER Fluids Measured with Laser Speckle

2011 ◽  
Vol 287-290 ◽  
pp. 2781-2784
Author(s):  
Ji Jun Fan ◽  
Nan Hui Yu
Keyword(s):  
Electric Field ◽  
High Speed ◽  
Ccd Camera ◽  
Laser Speckle ◽  
Time Intervals ◽  
Sample Concentration ◽  
Speckle Patterns ◽  
The Mean ◽  
Er Fluids ◽  
Short Time

In this paper, the principle of measuring infinitesimal displacement by laser speckle is proposed to measure the velocities of particles in ER fluids. It is verified that speckles can be formed by illuminating laser beam on the starch ER fluids. The speckle patterns was recorded with high speed CCD camera, and the speckle patterns sequences with short time intervals was obtained by intercepting laser speckle video. Displacements parallel to the direction of electric field and that perpendicular to the direction of electric field were obtained by processing the two consecutive speckle patterns. The experimental results showed that the velocities of particles decreased oscillatorily with time. There is a critical electric field and a critical sample concentration, when lower than this critical electric field (concentration), the mean particle velocity increased; otherwise, it decreased.

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