The Milne problem in a continuous stochastic planar medium with Gaussian statistics

2010 ◽  
Vol 111 (16) ◽  
pp. 2382-2389 ◽  
Author(s):  
M.M. Selim
Keyword(s):  
Milne Problem ◽  
Gaussian Statistics ◽  
Planar Medium

scholarly journals Independently Controlling Stochastic Field Realization Magnitude and Phase Statistics for the Construction of Novel Partially Coherent Sources

Photonics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 60
Author(s):  
Milo W. Hyde
Keyword(s):  
Coherent Beam ◽  
Optical Field ◽  
Stochastic Field ◽  
Partially Coherent ◽  
Second Moments ◽  
Coherent Beams ◽  
Gaussian Statistics ◽  
Simulated Field ◽  
Gaussian Moment ◽  
Partially Coherent Beams

In this paper, we present a method to independently control the field and irradiance statistics of a partially coherent beam. Prior techniques focus on generating optical field realizations whose ensemble-averaged autocorrelation matches a specified second-order field moment known as the cross-spectral density (CSD) function. Since optical field realizations are assumed to obey Gaussian statistics, these methods do not consider the irradiance moments, as they, by the Gaussian moment theorem, are completely determined by the field’s first and second moments. Our work, by including control over the irradiance statistics (in addition to the CSD function), expands existing synthesis approaches and allows for the design, modeling, and simulation of new partially coherent beams, whose underlying field realizations are not Gaussian distributed. We start with our model for a random optical field realization and then derive expressions relating the ensemble moments of our fields to those of the desired partially coherent beam. We describe in detail how to generate random optical field realizations with the proper statistics. We lastly generate two example partially coherent beams using our method and compare the simulated field and irradiance moments theory to validate our technique.

scholarly journals Input Parallel Output Series Structure of Planar Medium Frequency Transformers for 200 kW Power Converter: Model and Parameters Evaluation

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1450
Author(s):  
Alessandro La Ganga ◽  
Roberto Re ◽  
Paolo Guglielmi
Keyword(s):  
Electric Vehicles ◽  
High Performance ◽  
Power Converter ◽  
Electrical Model ◽  
Solid State Transformer ◽  
Medium Frequency ◽  
Analytical Treatment ◽  
Transformer Model ◽  
Planar Medium ◽  
Parallel Output

Nowadays, the demand for high power converters for DC applications, such as renewable sources or ultra-fast chargers for electric vehicles, is constantly growing. Galvanic isolation is mandatory in most of these applications. In this context, the Solid State Transformer (SST) converter plays a fundamental role. The adoption of the Medium Frequency Transformers (MFT) guarantees galvanic isolation in addition to high performance in reduced size. In the present paper, a multi MFT structure is proposed as a solution to improve the power density and the modularity of the system. Starting from 20kW planar transformer model, experimentally validated, a multi-transformer structure is analyzed. After an analytical treatment of the Input Parallel Output Series (IPOS) structure, an equivalent electrical model of a 200kW IPOS (made by 10 MFTs) is introduced. The model is validated by experimental measurements and tests.

Milne problem for a hard-sphere Rayleigh gas: A study based on the Fokker-Planck equation

1983 ◽  
Vol 28 (3) ◽  
pp. 1659-1661 ◽  
Author(s):  
S. Waldenstrøm ◽  
K. J. Mork ◽  
K. Razi Naqvi
Keyword(s):  
Hard Sphere ◽  
Planck Equation ◽  
Milne Problem ◽  
Fokker Planck Equation ◽  
Rayleigh Gas ◽  
Fokker Planck

The Milne Problem for a Periodic Medium

2004 ◽  
Vol 40 (8) ◽  
pp. 1113-1121 ◽  
Author(s):  
M. G. Muradyan
Keyword(s):  
Periodic Medium ◽  
Milne Problem

Extreme vertical drafts in the polar summer mesosphere: A super mesospheric bore?

2021 ◽  
Author(s):  
Jorge Luis Chau ◽  
Raffaele Marino ◽  
Fabio Feraco ◽  
Juan M. Urco ◽  
Gerd Baumgarten ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Extreme Event ◽  
Ice Clouds ◽  
Wind Variability ◽  
Near Space ◽  
The Earth ◽  
Radar Echoes ◽  
Gaussian Statistics ◽  
Non Gaussian ◽  
Impact Planning

<p>The polar summer mesosphere is the Earth’s coldest region, allowing the formation of mesospheric ice clouds, potentially linked to climate change. These clouds produce strong radar echoes that are used as tracers of mesospheric dynamics. Here we report the first observations of extreme vertical drafts in the mesosphere, characterized by velocities larger than 40 m/s, i.e., more than five standard deviations larger than the observed wind variability. The morphology seems to resemble mesospheric bores, however the scales observed are much larger. Powerful vertical drafts, intermittent in space and time, emerge also in direct numerical simulations of stratified flows, predicting non-Gaussian statistics of vertical velocities. This evidence suggests that mesospheric bores might result from the interplay of gravity waves and turbulent motions. Our extreme event is interpreted as a mesospheric "super-bore", impacting mesospheric mixing and ice-formation, and would potentially impact planning of sub-orbital flights, and the investigation of biological material in the near space.</p>

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