Exploring the effects of a time- and space-dependent eruption efficiency on planetary evolution.

2020 ◽  
Author(s):  
Mara Arts
Keyword(s):  
Local Stress ◽  
Terrestrial Planets ◽  
Conductive Heat ◽  
Time And Space ◽  
Planetary Evolution ◽  
Conductive Heat Flux ◽  
Consistent Manner ◽  
Local Stress State ◽  
Almost All ◽  
Mantle Temperature

<p>It has been shown that melting and crust production strongly influences the convection regime of terrestrial planets, potentially even more than the vigor of convection. A planet producing and erupting a lot of crust can hardly remain in the stagnant lid regime and produces resurfacings or even reaches some mobile-lid regime. On the other hand, a planet that intrudes its melt in the lithosphere tends to have a larger conductive heat flux and cools efficiently without much lid mobility. Thus, the question of the amount of melts being erupted or intruded might dominate the cooling of terrestrial planets. So far, an "eruption efficiency", which gives the ratio of melt that erupts over the remaining melt fraction, has been imposed in numerical simulations. The eruption efficiency in the convection code StagYY has thus far been treated as a constant in time and space. Here, we explore the effects of a time- and space-dependent eruption efficiency on planetary evolution in the planetary convection code StagYY. An equation was devised that describes how eruptive a system is, based on the main characteristics of lithospheric melt transport: the amount of melt and the local stress state. In a range of systematic simulations, we explore the consequences of this parameter. </p><p>In a first set of simulations this parameter is explored while keeping the eruption efficiency constant. Results show that the most important parameters are the amount of melt, where the stress has smaller local effects. Additionally, changing the yield stress, viscosity or constant eruption efficiency has a large effect on what the eruptivity should be based on this equation. Parameters that govern the global mantle temperature are less important for the eruptivity. </p><p>A second set of simulations was performed with the eruption efficiency behaving in a fully self-consistent manner. These models tend to behave like intrusive systems, except during resurfacing episodes when the models become very extrusive. Models that show mobile behaviour at almost all times in the planetary evolution will have an almost constant spatially averaged eruption efficiency. In these models the eruption efficiency does vary locally however.</p>

A Sense of (Be)longing in Shaun Tan's The Lost Thing

2010 ◽  
Vol 3 (2) ◽  
pp. 134-147 ◽  
Author(s):  
David Rudd
Keyword(s):  
Social Issues ◽  
Picture Book ◽  
Judith Butler ◽  
Close Reading ◽  
Giorgio Agamben ◽  
Time And Space ◽  
Zygmunt Bauman ◽  
Mary Douglas ◽  
Almost All ◽  
Feeling At Home

Almost all Shaun Tan's work explores notions of belonging, and related ideas about feeling at home (or not) in time and space. But these issues are most starkly explored in his first solo picture book, The Lost Thing (2000), where the narrator, Shaun, relates his discovery of a mysterious, large, red, hybrid being. This article undertakes a close reading of Tan's text, drawing on the work of theorists like Mary Douglas, Zygmunt Bauman, Giorgio Agamben and Judith Butler to show how societies, through their classificatory logic, manage to deal with any ‘matter out of place’. It also explores the particular poignancy of ‘misplaced’ things in the context of Australia, not only through the Howard Government's draconian treatment of refugees, but also in terms of the country's long-standing guilt about its treatment of the Aboriginal ‘stolen generation’, and of others, like the forcibly deported British children. In contrast to the more optimistic reading usually given to Tan's work, a darker, more menacing interpretation is suggested – though a note of hope is still detected in the narrator's need to record his story. In this way, The Lost Thing is not concerned solely with social issues, but engages with a more existential sense of longing that we can all experience.

Investigation of Constraint Effects on Fracture Toughness for CC(T) Specimens

2004 ◽  
Author(s):  
Dieter Siegele ◽  
Igor Varfolomeyev ◽  
Kim Wallin ◽  
Gerhard Nagel
Keyword(s):  
Fracture Toughness ◽  
Crack Tip ◽  
Temperature Shift ◽  
Local Stress ◽  
Significant Loss ◽  
Reference Temperature ◽  
T Stress ◽  
Local Stress State ◽  
Constraint Effects ◽  
Crack Tip Constraint

Within the framework of the European research project VOCALIST, centre cracked tension, CC(T), specimens made of an RPV steel were tested and analysed to quantify the influence of local stress state on fracture toughness. The CC(T) specimens demonstrate a significant loss of crack tip constraint resulting in a considerable increase in fracture toughness as compared to standard fracture mechanics specimens. So, the master curve reference temperature, To, determined on the basis of CC(T) tests performed in this study is about 43°C lower than To obtained on standard C(T) specimens. Finite element analyses of the tests revealed that the above experimental finding is in a good agreement with the empirical correlations between the reference temperature shift and the crack tip constraint as characterised by the T-stress or Q parameter (Wallin, 2001; Wallin, 2004). The results of this work are consistent with a number of other tests performed within the VOCALIST project and contribute to the validation of engineering methods for the crack assessment in components taking account of constraint.

Granites and crustal heat budget

2019 ◽  
Vol 491 (1) ◽  
pp. 77-100 ◽  
Author(s):  
Jean-François Moyen
Keyword(s):  
Heat Production ◽  
Heat Budget ◽  
Internal Heat ◽  
Balance Model ◽  
Conductive Heat ◽  
Crustal Melting ◽  
Abstract Approach ◽  
Production And Consumption ◽  
Conductive Heat Flux ◽  
Basalt Differentiation

AbstractThe origin of large I-type batholiths remains a disputed topic. One model states that I-type granites form by partial melting of older crustal lithologies (amphibolites or intermediate igneous rocks). In another view, granites are trapped rhyolitic liquids occurring at the end of fractionation trends defining a basalt–andesite–dacite–rhyolite series. This paper explores the thermal implications of both scenarios, using a heat balance model that abstracts the heat production and consumption during crustal melting. Heat is consumed by melting and by losses through the surface (conductive or advective, as a result of eruption). It is supplied as a basal conductive heat flux, as internal heat production or as advective heat carried by an influx of hot basalt into the crust. Using this abstract approach, it is possible to explore the role different parameters play in the balance of granites formed by differentiation of basalts or by crustal melting. Two end-member situations appear equally favourable to generating large volumes of granites: (1) short-lived environments dominated by high basaltic flux, where granites result mostly from basalt differentiation; and (2) long-lived systems with no or minimal basalt flux, with granites resulting chiefly from crustal melting.

Close analogy between radiative and conductive heat flux in a finite slab

AIAA Journal ◽  
1964 ◽  
Vol 2 (12) ◽  
pp. 2180-2186 ◽  
Author(s):  
MAX A. HEASLET ◽  
BARRETT BALDWIN
Keyword(s):  
Heat Flux ◽  
Conductive Heat ◽  
Close Analogy ◽  
Finite Slab ◽  
Conductive Heat Flux
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