Aspect Ratio Research Papers - Academia.edu (original) (raw)

Chocolate-tablet boudins of quartzite are restricted to steep limbs of D1-folds along the SW coast of Portugal. The chocolate-tablet geometry results from older vertical and younger horizontal quartz veins. Both sets of veins developed... more

Chocolate-tablet boudins of quartzite are restricted to steep limbs of D1-folds along the SW coast of Portugal. The chocolate-tablet geometry results from older vertical and younger horizontal quartz veins. Both sets of veins developed during similar conditions by extension fracture in pre-existing necked domains: (1) both veins show stretched crystal fibers; (2) the boudin aspect ratio is the same in vertical (3.0 ± 1.4) and in horizontal sections (2.9 ± 1.2); (3) temperatures obtained from fluid inclusions are similar (200 ± 20° for vertical and 230 ± 22 °C for horizontal veins) and are compatible with temperatures obtained from illite crystallinity (ca. 200–ca. 250 °C). Given thermal equilibrium between the host rock and the precipitating fluid, the chocolate-tablet boudins formed close to the metamorphic peak. We interpret that the vertical veins developed after the limbs of the D1-folds had attained their steep attitude and the orientation of the greatest and intermediate principal strain axes had interchanged. Subsequently, the initial strain field was restored and opening of horizontal veins led to the chocolate-tablet geometry. The direction of the main shortening direction was constant from the initial buckling stage via isoclinal folding and during all boudinage stages.► The paper deals with chocolate-tablet boudins well exposed in 3D. ► The boudin aspect ratio (ca. 3) is the same in horizontal and vertical sections. ► Vertical and horizontal fractures of neck domains developed in sequence. ► Boudinage occurred during progressive shortening close to the metamorphic peak.

The evolution of the microstructure of an assembly of cohesionless granular materials with associated pores, which carry the overall applied stresses through frictional contacts is a complex phenomenon. The macroscopic flow of such... more

The evolution of the microstructure of an assembly of cohesionless granular materials with associated pores, which carry the overall applied stresses through frictional contacts is a complex phenomenon. The macroscopic flow of such materials take place by the virtue of the relative rolling and sliding of the grains on the micro-scale. A new discrete element method for biaxial compression simulations of random assemblies of oval particles with mixed sizes is introduced. During the course of deformation, the new positions of the grains are determined by employing the static equilibrium equations. A key aspect of the method is that, it is formulated for ellipse cross-sectional particles, hence desirable inherent anisotropies are possible. A robust algorithm for the determination of the contact points between neighbouring grains is given. Employing the present methodology, many aspects of the behaviour of two-dimensional assemblies of oval cross-sectional rods have been successfully addressed. The effects of initial void ratio, interparticle friction angle, aspect ratio, and bedding angle on the rolling and sliding contacts are examined. The distribution of normals to the rolling and sliding contacts have different patterns and are concentrated along directions, which are approximately perpendicular to one another. On the other hand, the distribution of all contact normals (combined rolling and sliding) are close to that of rolling contacts, which confirm that rolling is the dominant mechanism. This phenomenon becomes more pronounced for higher intergranular friction angle. Characteristics of the rolling and sliding contacts are also discussed in the context of the force angle, which is the inclination of contact force with respect to the contact normal.

A numerical simulation has been carried out to investigate the buoyancy induced flow and heat transfer characteristics inside a wavy walled enclosure. The enclosure consists of two parallel wavy and two straight walls. The top and the... more

A numerical simulation has been carried out to investigate the buoyancy induced flow and heat transfer characteristics inside a wavy walled enclosure. The enclosure consists of two parallel wavy and two straight walls. The top and the bottom walls are wavy and kept isothermal. Two straight-vertical sidewalls are considered adiabatic. Governing equations are discretized using the control volume based Finite-Volume method with collocated variable arrangement. Simulation was carried out for a range of surface waviness ratios, =0.00-0.25; aspect ratios, A=0.25-0.5; and Rayleigh numbers Ra=100-107 for a fluid having Prandtl number equal to 1.0. Results are presented in the form of local and global Nusselt number distributions, streamlines, and isothermal lines for different values of surface waviness and aspect ratios. For a special case of =0 and A=1.0, the average Nusselt number distribution is compared with available reference. The results suggest that natural convection heat transfer is changed considerably when surface waviness changes and also depends on the aspect ratio of the domain. In addition to the heat transfer results, the heat transfer irreversibility (HTI) in terms of Bejan number (Be) was measured. For a set of selected values of the parameters (, A, and Ra), a contour of the Bejan number is presented at the end of this paper.

This paper presents work in progress and continues a project devoted to developing shape modeling system for surface generation and enhancement. A local mesh enhancement based on statistical characteristics of an initial triangle mesh is... more

This paper presents work in progress and continues a project devoted to developing shape modeling system for surface generation and enhancement. A local mesh enhancement based on statistical characteristics of an initial triangle mesh is proposed for mesh simplification. Experimental results are included to demonstrate the functionality of our simplification algorithm.

The well-acknowledged etch profile drift problem in chip production was investigated with a more accurate means of measuring actual etch thickness to monitor and correct this drift. Using a high-aspect ratio, 0.1m -Si gate structure, the... more

The well-acknowledged etch profile drift problem in chip production was investigated with a more accurate means of measuring actual etch thickness to monitor and correct this drift. Using a high-aspect ratio, 0.1m -Si gate structure, the investigation was specifically focused on the control of transition timing in the critical interval from main etch (ME) to over etch (OE). This required reliable endpoint detection of -Si which was achieved through the development of a method employing a Kalman–Bucy filter with a real-time spectroscopic ellipsometer (RTSE). The robustness of our endpoint detection technique was tested and demonstrated under the actual physical and chemical disturbance environments of the etching process. Application of this endpoint detection technique to the etch of a 0.1-m patterned -Si gate also achieved a significant improvement on the etch profile repeatability.

Hydroxyapatite has been considered for use in the repair of osseous defects for the last 20 years. Recent developments have led to interest in the potential of porous hydroxyapatite as a synthetic bone graft. However, despite considerable... more

Hydroxyapatite has been considered for use in the repair of osseous defects for the last 20 years. Recent developments have led to interest in the potential of porous hydroxyapatite as a synthetic bone graft. However, despite considerable activity in this field, regarding assessment of the biological response to such materials, the basic materials characterization is often inadequate. This paper documents the characterization of the chemical composition, mechanical integrity, macro- and microstructure of a porous hydroxyapatite, Endobon (E. Merck GmbH), intended for the bone-graft market. Specimens possesed a range of apparent densities from 0.35 to 1.44 g cm(-3). Chemical analysis demonstrated that the natural apatite precursor of Endobon was not converted to pure hydroxyapatite, but retained many of the ionic substituents found in bone mineral, notably carbonate, sodium and magnesium ions. Investigation of the microstructure illustrated that the struts of the material were not ful...