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.

Contractile Filament Stress in the Left Ventricle and its Relationship to Wall Stress

1979 ◽  
Vol 101 (4) ◽  
pp. 225-231 ◽  
Author(s):  
E. S. Grood ◽  
C. A. Phillips ◽  
R. E. Mates
Keyword(s):  
Three Dimensional ◽  
Wall Stress ◽  
One Dimensional ◽  
Muscle Work ◽  
Lumped Parameter ◽  
Pressure Development ◽  
The One ◽  
Active Force Generation ◽  
Muscle Models ◽  
Significant Underestimation

A three-dimensional composite model of heart muscle is proposed, consisting of one-dimensional (uniaxial) active contractile filaments embedded in a passive elastic binder. Equations are developed which relate the force developed by the filaments to the local tissue stress. An approximate analysis is employed to determine the time variation of the contractile filament stress throughout the cardiac cycle from catheterization data. Results from 15 patients with normal left ventricles demonstrate that the stress developed by the contractile filaments is up to 25 percent more tensile than the wall stress, and that the binder stress is compressive during most of systole. In contrast, the one-dimensional lumped parameter muscle models previously employed predict active (CE) stresses less tensile than the wall stress and binder (PE) stresses that are tensile. We conclude that the use of a one-dimensional muscle model results in a significant underestimation of the active force generation required for pressure development and the power requirements for ejection. Prior studies relating muscle work and power to ventricular oxygen consumption should be re-examined in this light.

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.

Analysis of the Containment Thermal-Hydraulic Behavior of a Small Reactor During Loss of Coolant Accident

2017 ◽  
Author(s):  
Qian Lin ◽  
Weizhong Zhang
Keyword(s):  
Cooling System ◽  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
One Dimensional ◽  
Loss Of Coolant Accident ◽  
Lumped Parameter ◽  
Loss Of Coolant ◽  
Calculation Results ◽  
The One

The containment thermal hydraulics of a small reactor during loss of coolant accident (LOCA) is studied by a lumped parameter one-dimensional model and a three-dimensional model. The capability of a kind of heat exchanger type passive containment cooling system (PCCS) is analyzed by the one-dimensional model. The calculation results show that, the decay heat can be removed and the containment pressure can be decreased by the proposed PCCS. The steam and non-condensable gas (the air) distribution in the containment is investigated, the mixing and stratification behaviors are analyzed for several different cases, in which the PCCS and condenser are located at higher, base or lower position. The sensitivity analysis of the PCCS elevation shows that, in despite of the different gas stratification, the containment pressures are nearly the same. Similar conclusions can be obtained by the one-dimensional model and three-dimensional model. The preliminary results may indicate that, the designed PCCS and condenser can be located at a lower part, which will be benefit for the economy of the small reactor or meet other requirements.

Discrete spectra and dampes waves in quasilinear theory

1970 ◽  
Vol 4 (4) ◽  
pp. 677-691 ◽  
Author(s):  
George Vahala ◽  
David Montgomery
Keyword(s):  
Growth Rate ◽  
Continuous Wave ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Wave Number ◽  
Quasilinear Theory ◽  
One Dimensional ◽  
Zero Growth ◽  
The One ◽  
Discrete Spectra

The consequences of the quasilinear equations are explored. Particular attention is paid to the differences between the one-dimensional and the two- and three-dimensional cases, and to the differences between the cases of discrete and continuous wave-number spectra. The possibilities of and problems associated with including damped waves are treated. The relation between conservation laws and the ‘resonance approximation’, in which the limit of zero growth rate for the unstable waves is taken at finite times, is clarified. Numerical solutions for the one-dimensional case with finite growth rate are presented.

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.

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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