Melt Distribution and Gate Design

2021 ◽  
pp. 479-548
Author(s):  
Bruce Catoen ◽  
Herbert Rees
Keyword(s):  
Melt Distribution ◽  
Gate Design

Quantification of excess 231Pa in late Quaternary igneous baddeleyite

2020 ◽  
Vol 105 (12) ◽  
pp. 1830-1840 ◽  
Author(s):  
Yi Sun ◽  
Axel K. Schmitt ◽  
Lucia Pappalardo ◽  
Massimo Russo
Keyword(s):  
Late Quaternary ◽  
Central Italy ◽  
Direct Analysis ◽  
Weight Percent ◽  
Volcanic Field ◽  
Distribution Coefficients ◽  
Secular Equilibrium ◽  
Melt Distribution ◽  
D Values ◽  
Significant Figures

Abstract Initial excess protactinium (231Pa) is a frequently suspected source of discordance in baddeleyite (ZrO2) geochronology, which limits accurate U/Pb dating, but such excesses have never been directly demonstrated. In this study, Pa incorporation in late Holocene baddeleyite from Somma-Vesuvius (Campanian Volcanic Province, central Italy) and Laacher See (East Eifel Volcanic Field, western Germany) was quantified by U-Th-Pa measurements using a large-geometry ion microprobe. Baddeleyite crystals isolated from subvolcanic syenites have average U concentrations of ~200 ppm and are largely stoichiometric with minor abundances of Nb, Hf, Ti, and Fe up to a few weight percent. Measured (231Pa)/(235U) activity ratios are significantly above the secular equilibrium value of unity and range from 3.4(8) to 14.9(2.6) in Vesuvius baddeleyite and from 3.6(9) to 8.9(1.4) in Laacher See baddeleyite (values within parentheses represent uncertainties in the last significant figures reported as 1σ throughout the text). Crystallization ages of 5.12(56) ka (Vesuvius; MSWD = 0.96, n = 12) and 15.6(2.0) ka (Laacher See; MSWD = 0.91, n = 10) were obtained from (230Th)/(238U) disequilibria for the same crystals, which are close to the respective eruption ages. Applying a corresponding age correction indicates average initial (231Pa)/(235U)0 of 8.8(1.0) (Vesuvius) and 7.9(5) (Laacher See). For reasonable melt activities, model baddeleyite-melt distribution coefficients of DPa/DU = 5.8(2) and 4.1(2) are obtained for Vesuvius and Laacher See, respectively. Speciation-dependent (Pa4+ vs. Pa5+) partitioning coefficients (D values) from crystal lattice strain models for tetra- and pentavalent proxy ions significantly exceed DPa/DU inferred from direct analysis of 231Pa for Pa5+. This is consistent with predominantly reduced Pa4+ in the melt, for which D values similar to U4+ are expected. Contrary to common assumptions, baddeleyite-crystallizing melts from Vesuvius and Laacher See appear to be dominated by Pa4+ rather than Pa5+. An initial disequilibrium correction for baddeleyite geochronology using DPa/DU = 5 ± 1 is recommended for oxidized phonolitic melt compositions.

Vortex-gate design for gravity casting

2006 ◽  
Vol 19 (1) ◽  
pp. 38-44 ◽  
Author(s):  
F.-Y. Hsu ◽  
M. R. Jolly ◽  
J. Campbell
Keyword(s):  
Gravity Casting ◽  
Gate Design

scholarly journals ECL-Based SiC Logic Circuits for Extreme Temperatures

2015 ◽  
Vol 821-823 ◽  
pp. 910-913 ◽  
Author(s):  
Luigia Lanni ◽  
Bengt Gunnar Malm ◽  
Mikael Östling ◽  
Carl Mikael Zetterling
Keyword(s):  
Power Consumption ◽  
Oscillation Frequency ◽  
Digital Circuits ◽  
Supply Voltage ◽  
Logic Circuits ◽  
Ring Oscillator ◽  
Extreme Temperatures ◽  
Temperature Range ◽  
Stable Noise ◽  
Gate Design

Integrated digital circuits, fabricated in a bipolar SiC technology, have been successfully tested up to 600 °C. Operated with-15 V supply voltage from 27 up to 600 °C OR-NOR gates exhibit stable noise margins of about 1 or 1.5 V depending on the gate design, and increasing delay-power consumption product in the range 100 - 200 nJ. In the same temperature range an oscillation frequency of about 1 MHz is also reported for an 11-stage ring oscillator.

Side-Gate Design Optimization of 50 nm MOSFETs with Electrically Induced Source/Drain

2002 ◽  
Vol 41 (Part 1, No. 4B) ◽  
pp. 2345-2347 ◽  
Author(s):  
Woo Young Choi ◽  
Byung Yong Choi ◽  
Dong Soo Woo ◽  
Young Jin Choi ◽  
Jong Duk Lee ◽  
...  
Keyword(s):  
Design Optimization ◽  
Gate Design

scholarly journals The Potsdam Parallel Ice Sheet Model (PISM-PIK) – Part 2: Dynamic equilibrium simulation of the Antarctic ice sheet

2011 ◽  
Vol 5 (3) ◽  
pp. 727-740 ◽  
Author(s):  
M. A. Martin ◽  
R. Winkelmann ◽  
M. Haseloff ◽  
T. Albrecht ◽  
E. Bueler ◽  
...  
Keyword(s):  
Steady State ◽  
Dynamic Equilibrium ◽  
Ice Sheet ◽  
Surface Velocity ◽  
Surface Mass ◽  
Ross Ice Shelf ◽  
Bed Topography ◽  
Melt Distribution ◽  
Spreading Rates ◽  
Equilibrium Simulation

Abstract. We present a dynamic equilibrium simulation of the ice sheet-shelf system on Antarctica with the Potsdam Parallel Ice Sheet Model (PISM-PIK). The simulation is initialized with present-day conditions for bed topography and ice thickness and then run to steady state with constant present-day surface mass balance. Surface temperature and sub-shelf basal melt distribution are parameterized. Grounding lines and calving fronts are free to evolve, and their modeled equilibrium state is compared to observational data. A physically-motivated calving law based on horizontal spreading rates allows for realistic calving fronts for various types of shelves. Steady-state dynamics including surface velocity and ice flux are analyzed for whole Antarctica and the Ronne-Filchner and Ross ice shelf areas in particular. The results show that the different flow regimes in sheet and shelves, and the transition zone between them, are captured reasonably well, supporting the approach of superposition of SIA and SSA for the representation of fast motion of grounded ice. This approach also leads to a natural emergence of sliding-dominated flow in stream-like features in this new 3-D marine ice sheet model.

AlGaN-GaN heterostructure FETs with offset gate design

1997 ◽  
Vol 33 (14) ◽  
pp. 1255 ◽  
Author(s):  
R. Gaska ◽  
Q. Chen ◽  
J. Yang ◽  
M. Asif Khan ◽  
M.S. Shur ◽  
...  
Keyword(s):  
Heterostructure Fets ◽  
Gan Heterostructure ◽  
Gate Design

Melt segregation in the lower crust: how have experiments helped us?

1996 ◽  
Vol 87 (1-2) ◽  
pp. 73-83 ◽  
Author(s):  
Tracy Rushmer
Keyword(s):  
Lower Crust ◽  
Tectonic Setting ◽  
Experimental Studies ◽  
Crustal Rock ◽  
Melt Migration ◽  
Tectonic Environment ◽  
Rock Cores ◽  
Melt Distribution ◽  
Chemical Behaviour ◽  
Melt Segregation

ABSTRACT:The rheological and chemical behaviour of the lower crust during anatexis has been a major focus of geological investigations for many years. Modern studies of crustal evolution require significant knowledge, not only of the potential source regions for granites, but also of the transport paths and emplacement mechanisms operating during granite genesis. We have gained significant insights into the segregation and transport of granitoid melts from the results of experimental studies on rock behaviour during partial melting. Experiments performed on crustal rock cores under both hydrostatic conditions and during deformation have led, in part, to two conclusions. (1) The interfacial energy controlling melt distribution is anisotropic and, as a result, the textures deviate significantly from those predicted for ideal systems—planar solid-melt interfaces are developed in addition to triple junction melt pockets. The ideal dihedral angle model for melt distribution cannot be used as a constraint to predict melt migration in the lower crust. (2) The ‘critical melt fraction’ model, which requires viscous, granitic melt to remain in the source until melt fractions reach >25 vol%, is not a reliable model for melt segregation. The most recent experimental results on crustal rock cores which have helped advance our understanding of melt segregation processes have shown that melt segregation is controlled by several variables, including the depth of melting, the type of reaction and the volume change associated with that reaction. Larger scale processes such as tectonic environment determine the rate at which the lower crust heats and deforms, thus the tectonic setting controls the melt fraction at which segregation takes place, in addition to the pressure and temperature of the potential melting reactions. Melt migration therefore can occur at a variety of different melt fractions depending on the tectonic environment; these results have significant implications for the predicted geochemistry of the magmas themselves.

scholarly journals EIT-Based Photonic Crystals and Photonic Logic Gate Design

10.5772/33897 ◽  
2012 ◽  
Author(s):  
Teh-Chau Liau ◽  
Jin-Jei Wu ◽  
Jian Qi ◽  
Tzong-Jer Yang
Keyword(s):  
Photonic Crystals ◽  
Logic Gate ◽  
Gate Design
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