Second-order moment analysis of dispersion-managed solitons

1999 ◽  
Vol 17 (3) ◽  
pp. 445-451 ◽  
Author(s):  
P.-A. Belanger ◽  
C. Pare
Keyword(s):  
Second Order ◽  
Moment Analysis ◽  
Order Moment ◽  
Analysis Of Dispersion

scholarly journals Optical shape analysis based on discrete Fourier transform and second-order moment analysis of the brightness distribution for the detection of sub-micron range tracks in nuclear emulsion

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Atsuhiro Umemoto ◽  
Tatsuhiro Naka ◽  
Toshiyuki Nakano ◽  
Ryuta Kobayashi ◽  
Takuya Shiraishi ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Discrete Fourier Transform ◽  
Nuclear Emulsion ◽  
Optical Microscope ◽  
Brightness Distribution ◽  
Second Order ◽  
Moment Analysis ◽  
Order Moment ◽  
Fine Grained ◽  
Nano Imaging

Abstract To recognize sub-micron-range low-energy tracks recorded in a super-fine-grained nuclear emulsion (Nano Imaging Tracker), an elliptical fitting method was devised to analyze anisotropic images taken by an optical microscope. We report on this newly developed method using a discrete Fourier transform and second-order moment analysis of the brightness distribution. We succeeded in lowering the ellipticity threshold, thereby improving the selection efficiency and angular resolution. Notably, the success of detecting carbon 30 keV tracks is the first such achievement in the world, where the incident direction of carbon 30 keV ions was determined with an accuracy of 41$^\circ$ and an efficiency of $1.7 \pm 0.1\%$.

scholarly journals Method for Measuring the Second-Order Moment of Atmospheric Turbulence

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 564
Author(s):  
Hong Shen ◽  
Longkun Yu ◽  
Xu Jing ◽  
Fengfu Tan
Keyword(s):  
Atmospheric Turbulence ◽  
Weighting Function ◽  
Structure Constant ◽  
Turbulence Models ◽  
Second Order ◽  
Index Structure ◽  
Order Moment ◽  
Site Testing ◽  
Optical Effects ◽  
Novel Method

The turbulence moment of order m (μm) is defined as the refractive index structure constant Cn2 integrated over the whole path z with path-weighting function zm. Optical effects of atmospheric turbulence are directly related to turbulence moments. To evaluate the optical effects of atmospheric turbulence, it is necessary to measure the turbulence moment. It is well known that zero-order moments of turbulence (μ0) and five-thirds-order moments of turbulence (μ5/3), which correspond to the seeing and the isoplanatic angles, respectively, have been monitored as routine parameters in astronomical site testing. However, the direct measurement of second-order moments of turbulence (μ2) of the whole layer atmosphere has not been reported. Using a star as the light source, it has been found that μ2 can be measured through the covariance of the irradiance in two receiver apertures with suitable aperture size and aperture separation. Numerical results show that the theoretical error of this novel method is negligible in all the typical turbulence models. This method enabled us to monitor μ2 as a routine parameter in astronomical site testing, which is helpful to understand the characteristics of atmospheric turbulence better combined with μ0 and μ5/3.

A second-order moment method applied to gas-solid risers

AIChE Journal ◽  
2012 ◽  
Vol 58 (12) ◽  
pp. 3653-3675 ◽  
Author(s):  
Juhui Chen ◽  
Shuyan Wang ◽  
Dan Sun ◽  
Huilin Lu ◽  
Dimitri Gidaspow ◽  
...  
Keyword(s):  
Moment Method ◽  
Second Order ◽  
Order Moment

Shape Interpretation of Second-Order Moment Invariants

2016 ◽  
Vol 56 (1) ◽  
pp. 125-136 ◽  
Author(s):  
Joviša Žunić ◽  
Dragiša Žunić
Keyword(s):  
Second Order ◽  
Order Moment ◽  
Moment Invariants

scholarly journals Distributionally robust joint chance constraints with second-order moment information

2011 ◽  
Vol 137 (1-2) ◽  
pp. 167-198 ◽  
Author(s):  
Steve Zymler ◽  
Daniel Kuhn ◽  
Berç Rustem
Keyword(s):  
Chance Constraints ◽  
Second Order ◽  
Order Moment ◽  
Distributionally Robust

Simulation of Swirl Combustion and NO Formation Using Various Second Order Moment Turbulent Combustion Models and DNS Verification

2008 ◽  
Author(s):  
F. Wang ◽  
Y. Huang ◽  
L. X. Zhou ◽  
C. X. Xu ◽  
J. Cao
Keyword(s):  
Turbulent Combustion ◽  
Reaction Rate ◽  
Rate Coefficient ◽  
Second Order ◽  
Concentration Fluctuation ◽  
Order Moment ◽  
Combustion Model ◽  
Reaction Rate Coefficient ◽  
No Formation ◽  
Swirl Combustion

If the instantaneous chemistry reaction rate is taken as ws = Bρ2Y1Y2 exp(−E/RT) = ρ2Y1Y2K, here K is a contraction for the exponential term. Then, ignoring the three order fluctuation correlation term, the average reaction rate could be ws = ρ2(Y1Y2K + Y1′Y2′K + Y1K′Y2′ + Y2K′Y1′). The authors have simulated jet combustion and swirl combustion using this kind of second order moment (SOM) turbulent combustion model. The predictions are close to experimental data in most regions. In order to improve the SOM turbulent combustion model, the effect of various correlation moments in the simulation of turbulent swirl combustion and NO formation is studied by comparing different SOM turbulence-chemistry models, including the unified second-order moment (USM) model, the model accounting for only the time-averaged reaction-rate coefficient, the model accounting for only the concentration fluctuation and the model accounting for both the time-averaged reaction-rate coefficient and the concentration fluctuation. These models are incorporated into the FLUENT code for a methane-air swirling combustion and NO formation under various swirl numbers. The magnitude of various correlations and their effect on the time-averaged reaction rate are analyzed, and the simulation results are compared with the corresponding measurement results. The results showed that the USM model gives the best agreement with the experimental results and among various correlation moments the correlation of reaction-rate coefficient fluctuation with the concentration fluctuation is most important. Additionally, a direct numerical simulation (DNS) of three-dimensional channel turbulent reacting flows with consideration of buoyancy effect using a spectral method was carried out. The statistical results are shown that K′Y′ are larger than Y1′Y2′.

Simulation of Cantilever Column under the Isolation Device Considering Additional Moment

2012 ◽  
Vol 195-196 ◽  
pp. 684-687
Author(s):  
Hua Ying Zhang ◽  
Hui Li ◽  
Xin Zhang ◽  
Rui Song Pan
Keyword(s):  
Bending Moment ◽  
Simulation Method ◽  
Second Order ◽  
Order Moment ◽  
Isolation System ◽  
Vertical Bearing ◽  
Isolation Device ◽  
Column Comparison

To accurately simulate the second-order bending moment caused by the superstructure shift in the isolation system is difficult. A simulation method of considering the second-order moment is put forward in this paper, and which is used to obtain the push-over curve of the cantilever column. Comparison of the push-over curves that with or without considering the additional moment is shown in this paper. The comparison presents evidence reduction, and embodies the decrease of stiffness. This simulation method can effectively balance the affection of the upper structure shift to the vertical bearing member under the isolator.

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