Molecular dynamics of amorphous silica at very high pressures (135 GPa): Thermodynamics and extraction of structures through analysis of Voronoi polyhedra

1991 ◽  
Vol 44 (5) ◽  
pp. 2108-2121 ◽  
Author(s):  
James R. Rustad ◽  
David A. Yuen ◽  
Frank J. Spera
Keyword(s):  
Molecular Dynamics ◽  
Amorphous Silica ◽  
High Pressures ◽  
Voronoi Polyhedra ◽  
Very High

Ultimate H2 and CH4 adsorption in slit-like carbon nanopores at 298 K: a molecular dynamics study

RSC Advances ◽  
2014 ◽  
Vol 4 (44) ◽  
pp. 22848-22855 ◽  
Author(s):  
Eric Poirier
Keyword(s):  
Molecular Dynamics ◽  
Room Temperature ◽  
High Pressures ◽  
Gas Adsorption ◽  
Methane Storage ◽  
Molecular Dynamics Calculations ◽  
Ch4 Adsorption ◽  
Slit Pores ◽  
Very High ◽  
Carbon Slit Pores

Molecular dynamics calculations of gas adsorption in ideal carbon slit pores provide new insights into the physical limits of nanocarbons for hydrogen and methane storage at very high pressures and room temperature.

scholarly journals Gaseous combustion at high pressures. —Part X. The co-volume corrections, maximum temperatures and dissociation of steam and carbon dioxide in explosions

1928 ◽  
Vol 119 (782) ◽  
pp. 464-480
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Internal Energy ◽  
High Temperatures ◽  
High Pressures ◽  
Internal Combustion ◽  
Systematic Survey ◽  
Explosion Method ◽  
Maximum Temperatures ◽  
Very High

During the researches upon high-pressure explosions of carbonic oxide-air, hydrogen-air, etc., mixtures, which have been described in the previous papers of this series, a mass of data has been accumulated relating to the influence of density and temperature upon the internal energy of gases and the dissociation of steam and carbon dioxide. Some time ago, at Prof. Bone’s request, the author undertook a systematic survey of the data in question, and the present paper summarises some of the principal results thereof, which it is hoped will throw light upon problems interesting alike to chemists, physicists and internal-combustion engineers. The explosion method affords the only means known at present of determining the internal energies of gases at very high temperatures, and it has been used for this purpose for upwards of 50 years. Although by no means without difficulties, arising from uncertainties of some of the assumptions upon which it is based, yet, for want of a better, its results have been generally accepted as being at least provisionally valuable. Amongst the more recent investigations which have attracted attention in this connection should be mentioned those of Pier, Bjerrum, Siegel and Fenning, all of whom worked at low or medium pressures.

Molecular Dynamics Simulations on Melting of Aluminum

2013 ◽  
Vol 423-426 ◽  
pp. 935-938 ◽  
Author(s):  
Ji Feng Li ◽  
Xiao Ping Zhao ◽  
Jian Liu
Keyword(s):  
Molecular Dynamics ◽  
Melting Point ◽  
Molecular Dynamics Simulations ◽  
High Pressures ◽  
Ambient Pressure ◽  
Initial Porosity ◽  
Equilibrium Melting Point ◽  
Porosity Effect ◽  
Dynamics Simulations ◽  
Experimental Melting Point

Molecular dynamics simulations were performed to calculate the melting points of perfect crystalline aluminum to high pressures. Under ambientpressure, there exhibits about 20% superheating before melting compared to the experimental melting point. Under high pressures, thecalculated melting temperature increases with the pressure but at a decreasing rate, which agrees well with the Simon's melting equation. Porosity effect was also studied for aluminum crystals with various initial porosity at ambient pressure, which shows that the equilibrium melting point decreases with the initial porosity as experiments expect.

Responses of cerebral arteries and arterioles to acute hypotension and hypertension

1978 ◽  
Vol 234 (4) ◽  
pp. H371-H383 ◽  
Author(s):  
H. A. Kontos ◽  
E. P. Wei ◽  
R. M. Navari ◽  
J. E. Levasseur ◽  
W. I. Rosenblum ◽  
...  
Keyword(s):  
Pressure Range ◽  
High Pressures ◽  
Cerebral Arteries ◽  
Pial Arteries ◽  
Small Vessels ◽  
Size Dependent ◽  
Arterial Blood ◽  
Vascular Bed ◽  
Acute Hypotension ◽  
Very High

The responses of cerebral precapillary vessels to changes in arterial blood pressure were studied in anesthetized cats equipped with cranial windows for the direct observation of the pial microcirculation of the parietal cortex. Vessel responses were found to be size dependent. Between mean arterial pressures of 110 and 160 mmHg autoregulatory adjustments in caliber, e.g., constriction when the pressure rose and dilation when the pressure decreased, occurred only in vessels larger than 200 micron in diameter. Small arterioles, less than 100 micron in diameter, dilated only at pressures equal to or less than 90 mmHg; below 70 mmHg their dilation exceeded that of the larger vessels. When pressure rose to 170- 200 mmHg, small vessels dilated while the larger vessels remained constricted. At very high pressures (greater than 200 mmHg) forced dilation was frequently irreversible and was accompanied by loss of responsiveness to hypocapnia. Measurement of the pressure differences across various segments of the cerebral vascular bed showed that the larger surface cerebral vessels, extending from the circle of Willis to pial arteries 200 micron in diameter, were primarily responsible for the adjustments in flow over most of the pressure range.

scholarly journals Numerical simulations of non-spherical bubble collapse

2009 ◽  
Vol 629 ◽  
pp. 231-262 ◽  
Author(s):  
ERIC JOHNSEN ◽  
TIM COLONIUS
Keyword(s):  
Bubble Dynamics ◽  
High Pressures ◽  
Pressure Ratio ◽  
Free Field ◽  
Water Hammer ◽  
Incident Shock ◽  
Bubble Collapse ◽  
Shock Propagation ◽  
Potential Damage ◽  
Very High

A high-order accurate shock- and interface-capturing scheme is used to simulate the collapse of a gas bubble in water. In order to better understand the damage caused by collapsing bubbles, the dynamics of the shock-induced and Rayleigh collapse of a bubble near a planar rigid surface and in a free field are analysed. Collapse times, bubble displacements, interfacial velocities and surface pressures are quantified as a function of the pressure ratio driving the collapse and of the initial bubble stand-off distance from the wall; these quantities are compared to the available theory and experiments and show good agreement with the data for both the bubble dynamics and the propagation of the shock emitted upon the collapse. Non-spherical collapse involves the formation of a re-entrant jet directed towards the wall or in the direction of propagation of the incoming shock. In shock-induced collapse, very high jet velocities can be achieved, and the finite time for shock propagation through the bubble may be non-negligible compared to the collapse time for the pressure ratios of interest. Several types of shock waves are generated during the collapse, including precursor and water-hammer shocks that arise from the re-entrant jet formation and its impact upon the distal side of the bubble, respectively. The water-hammer shock can generate very high pressures on the wall, far exceeding those from the incident shock. The potential damage to the neighbouring surface is quantified by measuring the wall pressure. The range of stand-off distances and the surface area for which amplification of the incident shock due to bubble collapse occurs is determined.

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