Determination of the mean fission lifetime by using the one-dimensional Langevin equation

2006 ◽  
Vol 2 (4) ◽  
pp. 342
Author(s):  
A. Zerarka ◽  
K. Mahboub ◽  
V.G. Foester
Keyword(s):  
Langevin Equation ◽  
One Dimensional ◽  
The Mean ◽  
The One

Forward and Backward Running Waves in the Arteries: Analysis Using the Method of Characteristics

1990 ◽  
Vol 112 (3) ◽  
pp. 322-326 ◽  
Author(s):  
K. H. Parker ◽  
C. J. H. Jones
Keyword(s):  
Transient Flow ◽  
Impedance Analysis ◽  
Time Domain Analysis ◽  
Mean Velocity ◽  
One Dimensional ◽  
Acceleration And Deceleration ◽  
The Mean ◽  
The One ◽  
Made In

The one-dimensional equations of flow in the elastic arteries are hyperbolic and admit nonlinear, wavelike solutions for the mean velocity, U, and the pressure, P. Neglecting dissipation, the solutions can be written in terms of wavelets defined as differences of the Riemann invariants across characteristics. This analysis shows that the product, dUdP, is positive definite for forward running wavelets and negative definite for backward running wavelets allowing the determination of the net magnitude and direction of propagating wavelets from pressure and velocity measured at a point in the artery. With the linearizing assumption that intersecting wavelets are additive, the forward and backward running wavelets can be separately calculated. This analysis, applied to measurements made in the ascending aorta of man, shows that forward running wavelets dominate during both the acceleration and deceleration phases of blood flow in the aorta. The forward and backward running waves calculated using the linearized analysis are similar to the results of an impedance analysis of the data. Unlike the impedance analysis, however, this is a time domain analysis which can be applied to nonperiodic or transient flow.

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 Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Ahmed M Helmi
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Water Level ◽  
Dimensional Analysis ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Cfd Simulations ◽  
One Dimensional ◽  
The Mean ◽  
The One

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

Microscale temperature and velocity spectra in the atmospheric boundary layer

1977 ◽  
Vol 83 (3) ◽  
pp. 547-567 ◽  
Author(s):  
R. M. Williams ◽  
C. A. Paulson
Keyword(s):  
Reynolds Number ◽  
Prandtl Number ◽  
Temperature Fluctuations ◽  
Inertial Subrange ◽  
Velocity Fluctuations ◽  
One Dimensional ◽  
Temperature Spectra ◽  
The Mean ◽  
Velocity Spectra ◽  
The One

High-frequency fluctuations in temperature and velocity were measured at a height of 2 m above a harvested, nearly level field of rye grass. Conditions were both stably and unstably stratified. Reynolds numbers ranged from 370000 to 740000. Measurements of velocity were made with a hot-wire anemometer and measurements of temperature with a platinum resistance element which had a diameter of 0[sdot ]5 μm and a length of 1 mm. Thirteen runs ranging in length from 78 to 238 s were analysed.Spectra of velocity fluctuations are consistent with previously reported universal forms. Spectra of temperature, however, exhibit an increase in slope with increasing wavenumber as the maximum in the one-dimensional dissipation spectrum is approached. The peak of the one-dimensional dissipation spectrum for temperature fluctuations occurs at a higher wavenumber than that of simultaneous spectra of the dissipation of velocity fluctuations. It is suggested that the change in slope of the temperature spectra and the dissimilarity between temperature and velocity spectra may be due to spatial dissimilarity in the dissipation of temperature and velocity fluctuations. The temperature spectra are compared with a theoretical prediction for fluids with large Prandtl number, due to Batchelor (1959). Even though air has a Prandtl number of 0[sdot ]7, the observations are in qualitative agreement with predictions of the theory. The non-dimensional wavenumber at which the increase in slope occurs is about 0[sdot ]02, in good agreement with observations in the ocean reported by Grantet al. (1968).For the two runs for which the stratification was stable, the normalized spectra of the temperature derivative fall on average slightly below the mean of the spectra of the remaining runs in the range in which the slope is approximately one-third. Hence the Reynolds number may not have always been sufficiently high to satisfy completely the conditions for an inertial subrange.Universal inertial-subrange constants were directly evaluated from one-dimensional dissipation spectra and found to be 0[sdot ]54 and 1[sdot ]00 for velocity and temperature, respectively. The constant for velocity is consistent with previously reported values, while the value for temperature differs from some of the previous direct estimates but is only 20% greater than the mean of the indirect estimates. This discrepancy may be explained by the neglect in the indirect estimates of the divergence terms in the conservation equation for the variance of temperature fluctuations. There is weak evidence that the one-dimensional constant, and hence the temperature spectra, may depend upon the turbulence Reynolds number, which varied from 1200 to 4300 in the observations reported.

Numerical study of the one-dimensional Hubbard model in determination of trans-polyacetylene properties

2001 ◽  
Vol 296 (4) ◽  
pp. 377-387 ◽  
Author(s):  
S. Goumri-Said ◽  
R. Moussa ◽  
J.P. DuFour ◽  
L. Salomon ◽  
H. Aourag
Keyword(s):  
Hubbard Model ◽  
Numerical Study ◽  
One Dimensional ◽  
The One

Integration of one-dimensional equations of motions

2020 ◽  
pp. 79-90
Author(s):  
Gleb L. Kotkin ◽  
Valeriy G. Serbo
Keyword(s):  
Potential Energy ◽  
Field Change ◽  
One Dimensional ◽  
System A ◽  
Small Correction ◽  
The Law ◽  
The One ◽  
The Given ◽  
Equations Of Motions

If the potential energy is independent of time, the energy of the system remains constant during the motion of a closed system. A system with one degree of freedom allows for the determination of the law of motion in quadrature. In this chapter, the authors consider motion of the particles in the one-dimensional fields. They discuss also how the law and the period of a particle moving in the potential field change due to adding to the given field a small correction.

scholarly journals Tomographic retrievals of ozone with the OMPS Limb Profiler: algorithm description and preliminary results

2018 ◽  
Vol 11 (4) ◽  
pp. 2375-2393 ◽  
Author(s):  
Daniel J. Zawada ◽  
Landon A. Rieger ◽  
Adam E. Bourassa ◽  
Douglas A. Degenstein
Keyword(s):  
Polar Vortex ◽  
Retrieval Algorithm ◽  
Vertical Profiles ◽  
Two Dimensional ◽  
One Dimensional ◽  
Preliminary Results ◽  
Horizontal Gradients ◽  
The Mean ◽  
The One

Abstract. Measurements of limb-scattered sunlight from the Ozone Mapping and Profiler Suite Limb Profiler (OMPS-LP) can be used to obtain vertical profiles of ozone in the stratosphere. In this paper we describe a two-dimensional, or tomographic, retrieval algorithm for OMPS-LP where variations are retrieved simultaneously in altitude and the along-orbital-track dimension. The algorithm has been applied to measurements from the center slit for the full OMPS-LP mission to create the publicly available University of Saskatchewan (USask) OMPS-LP 2D v1.0.2 dataset. Tropical ozone anomalies are compared with measurements from the Microwave Limb Sounder (MLS), where differences are less than 5 % of the mean ozone value for the majority of the stratosphere. Examples of near-coincident measurements with MLS are also shown, and agreement at the 5 % level is observed for the majority of the stratosphere. Both simulated retrievals and coincident comparisons with MLS are shown at the edge of the polar vortex, comparing the results to a traditional one-dimensional retrieval. The one-dimensional retrieval is shown to consistently overestimate the amount of ozone in areas of large horizontal gradients relative to both MLS and the two-dimensional retrieval.

Structural determination of the group K capsular polysaccharide of Neisseriameningitidis: a 2D-NMR analysis

1985 ◽  
Vol 63 (10) ◽  
pp. 2781-2786 ◽  
Author(s):  
Francis Michon ◽  
Jean Robert Brisson ◽  
René Roy ◽  
Harold J. Jennings ◽  
Fraser E. Ashton
Keyword(s):  
Capsular Polysaccharide ◽  
2D Nmr ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Electronic Effects ◽  
Nmr Studies ◽  
Polysaccharide Antigen ◽  
One Dimensional ◽  
The One

The capsular polysaccharide antigen of Neisseriameningitidis group K was isolated by Cetavlon precipitation and purified by ion-exchange chromatography. The structure of the K polysaccharide was determined to a large extent by comprehensive proton and carbon-13 nuclear magnetic resonance (nmr) studies. In these studies one-dimensional and two-dimensional experiments were carried out directly on the K polysaccharide. The K polysaccharide is composed of the following repeating unit: -4)β-D-ManpNAcA(1→3) [4-OAc]β-D-ManpNAcA(1→. Except for the one-bond couplings between their anomeric carbons and protons [Formula: see text], all the nmr spectroscopic evidence was consistent with both 2-acetamido-2-deoxy-D-mannopyranosyluronic acid residues adopting the 4C1 (D) conformation and having the β-D-configuration. This ambiguity in [Formula: see text] is probably due to through-space electronic effects generated by the presence of contiguous carboxylated sugar residues in the K polysaccharide. The O-acetyl substituents of the K polysaccharide are essential for its antigenicity to group K polysaccharide-specific antibodies.

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