Preliminary grade and volume model of alluvial Sn-Au placers

1995 ◽  
Author(s):  
J.D. Bliss ◽  
W.D. Menzie
Keyword(s):  
Volume Model

scholarly journals Real Color Model of a Cadaver for Deep Brain Stimulation of the Subthalamic Nucleus

2021 ◽  
Vol 11 (11) ◽  
pp. 4999
Author(s):  
Chung-Yoh Kim ◽  
Jin-Seo Park ◽  
Beom-Sun Chung
Keyword(s):  
Deep Brain Stimulation ◽  
Subthalamic Nucleus ◽  
Brain Stimulation ◽  
Magnetic Resonance Images ◽  
Target Point ◽  
Anatomical Structures ◽  
Volume Model ◽  
Segmented Images ◽  
Volume Models ◽  
Deep Brain

When performing deep brain stimulation (DBS) of the subthalamic nucleus, practitioners should interpret the magnetic resonance images (MRI) correctly so they can place the DBS electrode accurately at the target without damaging the other structures. The aim of this study is to provide a real color volume model of a cadaver head that would help medical students and practitioners to better understand the sectional anatomy of DBS surgery. Sectioned images of a cadaver head were reconstructed into a real color volume model with a voxel size of 0.5 mm × 0.5 mm × 0.5 mm. According to preoperative MRIs and postoperative computed tomographys (CT) of 31 patients, a virtual DBS electrode was rendered on the volume model of a cadaver. The volume model was sectioned at the classical and oblique planes to produce real color images. In addition, segmented images of a cadaver head were formed into volume models. On the classical and oblique planes, the anatomical structures around the course of the DBS electrode were identified. The entry point, waypoint, target point, and nearby structures where the DBS electrode could be misplaced were also elucidated. The oblique planes could be understood concretely by comparing the volume model of the sectioned images with that of the segmented images. The real color and high resolution of the volume model enabled observations of minute structures even on the oblique planes. The volume models can be downloaded by users to be correlated with other patients’ data for grasping the anatomical orientation.

scholarly journals Effect of an Improved Yasutomi Pressure-Viscosity Relationship on the Elastohydrodynamic Line Contact Problem

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Vincenzo Petrone ◽  
Adolfo Senatore ◽  
Vincenzo D'Agostino
Keyword(s):  
High Pressure ◽  
Film Thickness ◽  
Free Volume ◽  
Experimental Studies ◽  
Line Contact ◽  
Volume Model ◽  
Free Volume Model ◽  
Pressure Area ◽  
New Formulation ◽  
Lubricant Viscosity

This paper presents the application of an improved Yasutomi correlation for lubricant viscosity at high pressure in a Newtonian elastohydrodynamic line contact simulation. According to recent experimental studies using high pressure viscometers, the Yasutomi pressure-viscosity relationship derived from the free-volume model closely represents the real lubricant piezoviscous behavior for the high pressure typically encountered in elastohydrodynamic applications. However, the original Yasutomi correlation suffers from the appearance of a zero in the function describing the pressure dependence of the relative free volume thermal expansivity. In order to overcome this drawback, a new formulation of the Yasutomi relation was recently developed by Bair et al. This new function removes these concerns and provides improved precision without the need for an equation of state. Numerical simulations have been performed using the improved Yasutomi model to predict the lubricant pressure-viscosity, the pressure distribution, and the film thickness behavior in a Newtonian EHL simulation of a squalane-lubricated line contact. This work also shows that this model yields a higher viscosity at the low-pressure area, which results in a larger central film thickness compared with the previous piezoviscous relations.

Free volume model for positronium decay in molecular materials

1969 ◽  
Vol 28 (11) ◽  
pp. 760-761 ◽  
Author(s):  
B.V. Thosar ◽  
V.G. Kulkarni ◽  
R.G. Lagu ◽  
Girish Chandra
Keyword(s):  
Free Volume ◽  
Molecular Materials ◽  
Volume Model ◽  
Free Volume Model ◽  
Positronium Decay

scholarly journals A Finite-Volume Icosahedral Shallow-Water Model on a Local Coordinate

2009 ◽  
Vol 137 (4) ◽  
pp. 1422-1437 ◽  
Author(s):  
Jin-Luen Lee ◽  
Alexander E. MacDonald
Keyword(s):  
Shallow Water ◽  
Finite Volume ◽  
Spherical Surface ◽  
Second Order ◽  
Water Model ◽  
Numerical Dissipation ◽  
Shallow Water Model ◽  
Finite Volume Model ◽  
Volume Model ◽  
Cartesian Coordinate

Abstract An icosahedral-hexagonal shallow-water model (SWM) on the sphere is formulated on a local Cartesian coordinate based on the general stereographic projection plane. It is discretized with the third-order Adam–Bashforth time-differencing scheme and the second-order finite-volume operators for spatial derivative terms. The finite-volume operators are applied to the model variables defined on the nonstaggered grid with the edge variables interpolated using polynomial interpolation. The projected local coordinate reduces the solution space from the three-dimensional, curved, spherical surface to the two-dimensional plane and thus reduces the number of complete sets of basis functions in the Vandermonde matrix, which is the essential component of the interpolation. The use of a local Cartesian coordinate also greatly simplifies the mathematic formulation of the finite-volume operators and leads to the finite-volume integration along straight lines on the plane, rather than along curved lines on the spherical surface. The SWM is evaluated with the standard test cases of Williamson et al. Numerical results show that the icosahedral SWM is free from Pole problems. The SWM is a second-order finite-volume model as shown by the truncation error convergence test. The lee-wave numerical solutions are compared and found to be very similar to the solutions shown in other SWMs. The SWM is stably integrated for several weeks without numerical dissipation using the wavenumber 4 Rossby–Haurwitz solution as an initial condition. It is also shown that the icosahedral SWM achieves mass conservation within round-off errors as one would expect from a finite-volume model.

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