Influence of the pressure field distribution in transcranial ultrasonic neurostimulation

2013 ◽  
Vol 40 (8) ◽  
pp. 082902 ◽  
Author(s):  
Youliana Younan ◽  
Thomas Deffieux ◽  
Benoit Larrat ◽  
Mathias Fink ◽  
Mickael Tanter ◽  
...  
2013 ◽  
Vol 341-342 ◽  
pp. 546-549
Author(s):  
Hui Li ◽  
Rui Hua Hu

Based on the principle and method of computational fluid dynamics (CFD), using the software, FLUENT, the inner water flow field in the cross-section geometric model of a triangle-arranged tubular heat exchanger was simulated and the flow details were studied roundly. This article analyzed the temperature field distribution, pressure field distribution and pointed out the main factors that affected the effect of the heat transfer. The results of this paper provided a good base and reference for the further research on the optimum design.


2013 ◽  
Vol 716 ◽  
pp. 559-564
Author(s):  
Di Jia ◽  
Feng Hui Kang ◽  
Yi Na Wang

In order to study the acoustic environment of a ship sonar platform, near-field acoustic characteristic of a compound structure with plates & a cylindrical shell (CSPCS) subjected to sound excitation is researched based on numerical simulation. Influence of frequency and sound incident angle on acoustic environment of CSPCS are studied. Study shows that the sound pressure field distribution of CSPCS is complicated. Sound pressure would be strengthened and weakened in different locations when sound pressure uniformly incident into CSPCS. Result shows that the sound pressure distribution is highly dependent on frequency and incident angle. Sound pressure field is more evenly distributed when sound wave frequency is low. Study also shows that the incident angle has considerable influence on the sound field distribution of strengthened and weakened area.


2014 ◽  
Vol 620 ◽  
pp. 437-442
Author(s):  
Chun Xi Dai ◽  
Jun Peng Shao ◽  
Yan Qin Zhang ◽  
Xiao Dong Yu ◽  
Bo Wu

Large size hydrostatic bearing is the core component of heavy CNC equipment. The influence of pressure, heating and running time can reduce film thickness during operation. This will directly affect machining accuracy and operation reliability of the entire machine. Aiming at the problem of influence of rotational velocity on carrying capacity of heavy hydrostatic bearing, use finite volume method (FVM) to simulate gap film pressure field of heavy hydrostatic bearing with Constant Flow and study pressure field distribution law on the conditions of the different rotational velocity and same cavity depth, oil cavity area, then optimize oil cavity structure. Results show that, pressure field distribution law of the different rotational velocity is basically identical, but its carrying capacity is different. From the relation curve of the pressure and rotational velocity can be seen, because of the dynamic pressure of existence, along with the increase of rotational velocity, carrying capacity gradually. The study is of vital theoretical significance for the improvement of machining accuracy of numerical control machine and the entire CNC equipment and provides valuable theoretical basis for the design of hydrostatic guide rail in engineering practice.


2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Prashant R. Waghmare ◽  
Sushanta K. Mitra

In capillary flow, integral momentum approach is used to derive the governing equation, which requires an expression for the pressure field at the inlet of the capillary. Generally, the pressure field for circular capillary is deduced with hemispherical control volume. This expression has been extended for other noncircular capillaries with an equivalent radius approximation. In case of high aspect ratio channels, the semicylindrical control volume needs to be considered. In the present study, the correct expression for the entrance pressure field for high aspect ratio capillaries is derived with such appropriate control volume.


2011 ◽  
Vol 71-78 ◽  
pp. 2112-2115 ◽  
Author(s):  
Hui Li ◽  
Xin Hui Ma

Because of excessive pressure loss when the gas went through distributor in fluidized bed (FB), based on the principle and method of computational fluid dynamics (CFD), using the software, FLUENT, the inner flow field in the fluidized bed with distributor was simulated. This article analyzed the three-dimensional velocity field distribution, pressure field distribution under the different arrangement of hole form. and the good advice was given on the structural optimization of the cold distributor.


Author(s):  
T. Yanaka ◽  
K. Shirota

It is significant to note field aberrations (chromatic field aberration, coma, astigmatism and blurring due to curvature of field, defined by Glaser's aberration theory relative to the Blenden Freien System) of the objective lens in connection with the following three points of view; field aberrations increase as the resolution of the axial point improves by increasing the lens excitation (k2) and decreasing the half width value (d) of the axial lens field distribution; when one or all of the imaging lenses have axial imperfections such as beam deflection in image space by the asymmetrical magnetic leakage flux, the apparent axial point has field aberrations which prevent the theoretical resolution limit from being obtained.


Author(s):  
M. Strojnik

Magnetic lenses operating in partial saturation offer two advantages in HVEM: they exhibit small cs and cc and their power depends little on the excitation IN. Curve H, Fig. 1, shows that the maximal axial flux density Bz max of one of the lenses investigated changes between points (3) and (4) by 5% as the excitation varies by 40%. Consequently, the designer can relax the requirements concerning the stability of the lens current supplies. Saturated lenses, however, can only be used if (i) unwanted fields along the optical axis can be controlled, (ii) 'wobbling' of the optical axis due to inhomogeneous saturation around the pole piece faces is prevented, (iii) ample ampere-turns can be squeezed into the space available, and (iv) the lens operating point covers a sufficient range of accelerating voltages.


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