Like-particle collisional interactions in an inhomogeneous plasma

1976 ◽  
Vol 15 (2) ◽  
pp. 269-277 ◽  
Author(s):  
F. Santini ◽  
F. Engelmann
Keyword(s):  
Inhomogeneous Plasma ◽  
Three Dimensional ◽  
Collision Operator ◽  
Particle Collision ◽  
Equilibrium Potential ◽  
One Dimensional ◽  
Resonant Interactions ◽  
Particle Population ◽  
Collisional Interactions ◽  
Made In

A like-particle collision operator is derived for an inhomogeneous plasma with a periodic equilibrium potential which traps part of the particle population. The derivation is made in the guiding centre approximation (one-dimensional orbits along a strong magnetic field), and only resonant interactions are considered. The effect of the particle bouncing replaces that of the three-dimensional orbits in this limit. For resonances between different harmonics of the bounce motion the operator does not vanish as happens in the classical one-dimensional case. A discussion of the general equations describing this effect is presented together with some estimates.

Simulation Models of the Complex Type Pressure Wave Supercharger

2016 ◽  
Vol 823 ◽  
pp. 341-346
Author(s):  
Sebastian Radu ◽  
Marius Hârceagă ◽  
Gheorghe Alexandru Radu ◽  
Cristian Leahu ◽  
Horia Abăităncei ◽  
...  
Keyword(s):  
Pressure Wave ◽  
Rotation Speed ◽  
Three Dimensional ◽  
Simulation Models ◽  
Pressure Waves ◽  
Complex Type ◽  
One Dimensional ◽  
Fluent Software ◽  
Type Pressure ◽  
Made In

In order to efficiently supercharge Diesel engines with pressure wave superchargers it is necessary to correlate the superchargers rotation speed with certain parameters of the supercharged engine. For this purpose, to reduce the research costs and duration, simulation models can be used which help to determine the parameters which have a major impact on the supercharger's rotational speed and efficiency. In this paper there are presented two simulation models: a one-dimensional (made in AMESim software) and a three dimensional (made in Fluent Software). This simulation models offer the possibility to visualize some dynamic phenomenon within the supercharger, like the evolution of the pressure waves or the turbulent flow inside the rotor channels. These phenomena are difficult and expensive to study with conventional methods.

Wave packets, resonant interactions and soliton formation in inlet pipe flow

1993 ◽  
Vol 252 ◽  
pp. 1-30 ◽  
Author(s):  
Igor V. Savenkov
Keyword(s):  
Wave Packets ◽  
Three Dimensional ◽  
Short Wave ◽  
Nonlinear Interactions ◽  
Two Dimensional ◽  
Inlet Pipe ◽  
One Dimensional ◽  
Resonant Interactions ◽  
Dimensional Equation ◽  
Axisymmetric Disturbances

The development of disturbances (two-dimensional non-linear and three-dimensional linear) in the entrance region of a circular pipe is studied in the limit of Reynolds number R → ∞ in the framework of triple-deck theory. It is found that lower-branch axisymmetric disturbances can interact in the resonant manner. Numerical calculations show that a two-dimensional nonlinear wave packet grows much more rapidly than that in the boundary layer on a flat plate, producing a spike-like solution which seems to become singular at a finite time. Large-sized, short-scaled disturbances are also studied. In this case the development of axisymmetric disturbances is governed by single one-dimensional equation in the form of the Korteweg-de Vries and Benjamin-Ono equations in the long- and short-wave limits respectively. The nonlinear interactions of these disturbances lead to the formation of solitons which can run both upstream and downstream. Linear three-dimensional wave packets are also calculated.

Development of a General Procedure to Formulate Four Pole Parameters by Modal Expansion and Its Application to Three-Dimensional Cavities

1990 ◽  
Vol 112 (4) ◽  
pp. 452-459 ◽  
Author(s):  
J. Kim ◽  
W. Soedel
Keyword(s):  
Continuous Wave ◽  
Direct Method ◽  
General Procedure ◽  
Wave Length ◽  
Three Dimensional ◽  
Modal Expansion ◽  
One Dimensional ◽  
Pressure Profiles ◽  
Lumped Parameter ◽  
Made In

If an acoustic system has one or more large dimensions compared to the shortest wave length of interest, the pressure responses which are necessary to formulate four pole parameters have to be obtained by solving the continuous wave equation of the system. In this paper, a general procedure is established to derive four pole parameters from the pressure response solutions utilizing modal series expansion. As an example, four pole parameters of a cylindrically annular cavity are obtained. The validity of the procedure is proven by applying it also to a one-dimensional pipe whose four pole parameters are available by direct method. The comparison is made in terms of four pole parameters and pressure profiles along the pipe. The comparison allows interesting observations with regard to the equivalence of the two approaches. The theory was further generalized to be applied to more complex acoustic systems, namely multiply connected systems. A cylindrically annular cavity connected by two pipes to a small lumped parameter cavity is taken as an example of the application. Noise control by either mode cancellation or wave cancellation is explored.

The relation between the Wentzel-Kramers-Brillouin and the Thomas-Fermi approximations

1956 ◽  
Vol 235 (1202) ◽  
pp. 419-431 ◽  
Keyword(s):  
Three Dimensional ◽  
Coulomb Field ◽  
Central Field ◽  
Dimensional Problem ◽  
Field Problem ◽  
One Dimensional ◽  
Thomas Fermi ◽  
Energy Formula ◽  
The Individual ◽  
Made In

It is shown that two essential approximations are made in using the customary Thomas-Fermi formula for the sum of the eigenvalues in any one-dimensional problem. The first is to start from the Wentzel-Kramers-Brillouin formula for the individual eigenvalues, and the second is to replace the summation by an integration. The three-dimensional central field problem is then considered, and by similar arguments, though with an additional approximation, the usual Thomas-Fermi energy formula is again obtained. Possible ways of correcting the errors introduced by integrating instead of summing are discussed and illustrative examples given. In the three-dimensional case particular attention is given to the Coulomb field problem. Finally, brief reference is made to the possibility of correcting for the errors of the Wentzel-Kramers-Brillouin formula.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

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