Melt migration by reactive porosity waves

2021 ◽  
Author(s):  
Annelore Bessat ◽  
Sébastien Pilet ◽  
Stefan M. Schmalholz ◽  
Yuri Podladchikov
Keyword(s):  
Gibbs Energy ◽  
Numerical Algorithms ◽  
Wave Model ◽  
Physical Aspect ◽  
Melt Migration ◽  
Energy Minimisation ◽  
Porosity Wave ◽  
Low Degree ◽  
Silica Concentration ◽  
The Impact

<p>The formation of alkaline magmas observed worldwide requires that low degree-melts, potentially formed in the asthenosphere, were able to cross the overlying lithosphere. Fracturing in the upper, brittle part of the lithosphere may help to extract this melt to the surface. However, the mechanism of extraction in the lower, ductile part of the lithosphere is still contentious. Metasomatic enrichment of the lithospheric mantle demonstrates that such low-degree melts interact with the lithosphere, but the physical aspect of this process remains unclear.</p><p>Here, we aim to better understand, first, the percolation of magma in a porous viscous medium at pressure (P) and temperature (T) conditions relevant for the base of the lithosphere, and second, the impact of chemical differentiation on melt migration. We investigate theoretically the process of melt migration employing the fundamental laws of physics and thermodynamics. We simulate melt percolation numerically with a one-dimensional (1-D) Thermo-Hydro-Mechanical-Chemical (THMC) model of porosity waves coupled with thermodynamic results obtained from numerical Gibbs energy minimisation calculations. We perform THMC modelling and Gibbs energy minimisations with self-developed numerical algorithms using MATLAB and linear programming routines. We employ a simple ternary system of Forsterite/Fayalite/Enstatite for the solid and melt. Model variables, such as solid and melt densities or mass concentrations of MgO and SiO in solid and melt, are a function of pressure (P), temperature (T) and total silica concentration of the system (X). These variables are pre-computed with Gibbs energy minimisation and implemented in the THMC porosity wave transport code via parameterized equations, determining the T-P-X dependence of the model variables.</p><p>First results show that the total silica concentration and the temperature gradient are important parameters to consider in melt migration by reactive porosity waves. We discuss results of a systematic series of 1-D simulations and we present preliminary results form a 2-D reactive porosity wave model.</p>

Coupling between Thermo-Hydro-Chemical reactive transport and Gibbs minimisation: magma evolution in evolving multiphase porous media

2020 ◽  
Author(s):  
Annelore Bessat ◽  
Sébastien Pilet ◽  
Stefan M. Schmalholz ◽  
Yuri Podladchikov
Keyword(s):  
Gibbs Energy ◽  
Reactive Transport ◽  
Viscous Medium ◽  
Physical Aspect ◽  
Magma Evolution ◽  
Energy Minimisation ◽  
Transport Code ◽  
Low Degree ◽  
Melt Percolation ◽  
Alkaline Magmas

<p>The formation of alkaline magmas observed worldwide requires that low degree-melts, potentially formed in the asthenosphere, were able to cross the overlying lithosphere. Fracturing in the upper, brittle part of the lithosphere may help to extract this melt to the surface. However, the mechanism of extraction in the lower, ductile part of the lithosphere is still contentious. Metasomatic enrichment of the lithospheric mantle demonstrates that such low-degree melts interact with the lithosphere, but the physical aspect of this process remains unclear. The aim of this study is to better understand the percolation of magma in a porous viscous medium at pressure (P) and temperature (T) conditions relevant for the base of the lithosphere. We study such melt percolation numerically with a Thermo-Hydro-Chemical model of reactive transport coupled with thermodynamic data obtained via Gibbs energy minimisation. We perform Gibbs energy minimisation with Matlab using the linprog algorithm. We start with a simple ternary system of Forsterite/Fayalite/Enstatite solids and melts. All variables are a function of T, P and composition of the system (C), and are computed in both the Gibbs energy minimisation and in the reactive transport code, and can therefore vary freely.</p>

Transnationality in the XXI century. Concept and indicators

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Grazia Ietto-Gillies
Keyword(s):  
Structural Changes ◽  
Transnational Corporation ◽  
First Century ◽  
Future Research ◽  
Content Type ◽  
Low Degree ◽  
Fixed Assets ◽  
Inclusive Concept ◽  
The Impact

Purpose The purpose of this paper is to analyse the impact of major structural changes on the conceptualization of the transnational corporation (TNC) based on foreign direct investment (FDI) and on indicators of transnationality. Design/methodology/approach Analysis of three major structural changes which impact the current conception of transnationality. They are: the rise of digital companies; the increased role of finance in the economy; externalization of activities via non-equity modalities (NEMs) with an impact on FDI and on the labour market. Findings The paper finds that the current concept of transnationality needs widening to take account of companies with a low degree of fixed assets abroad such as the digital and the financial companies and those internationalizing via NEMs, as well as to take account of the evolving relationship between TNCs and labour. Research limitations/implications Future research along the lines proposed should consider: working explicitly with the new, inclusive concept of transnationality and arrive at an empirical estimate of the proposed indices of transnationality which modify and amplify the current United Nations Conference on Trade and Development indices. Social implications Useful for understanding the nature of transnationality in the twenty-first century and for developing policies. Originality/value The paper proposes a new concept of transnationality and of the TNC, one that allows for new ways of organizing direct business activities abroad. It also proposes broadening the list of indicators of transnationality.

Hydrodynamic Сonditions of the Bakalskaya Spit Degradation (Western Crimea) over the Past 30 Years

2021 ◽  
Vol 37 (3) ◽  
Author(s):  
B. V. Divinsky ◽  
R. D. Kosyan ◽  
◽  
Keyword(s):  
Discriminant Analysis ◽  
Coastal Zone ◽  
Satellite Images ◽  
Wind Waves ◽  
Total Duration ◽  
Wave Model ◽  
Statistical Characteristics ◽  
Wave Impact ◽  
Annual Variability ◽  
The Impact

Purpose. The paper is aimed at studying the morphodynamic features of the Bakalskaya Spit evolution being influenced by the sea wind waves and swell, namely assessment of inter-annual variations in the alluvial (erosion) areas of the Bakalskaya Spit coastline, analysis of inter-annual variability of the wind wave parameters, determination of the surface wave characteristics (or a combination of a few ones) responsible for the processes of the bottom material erosion or accumulation in the coastal zone. Methods and Results. Based on the analysis of satellite images for 1984–2016, the areas of the bottom material accumulation or erosion of the Bakalskaya Spit coastline were determined. Application of the spectral wave model permitted to obtain time series of the main parameters of wind waves and swell (significant wave heights and propagation directions) in the Bakalskaya Spit coastal zone with the 1 hr time resolution for the period from 1984 to 2016. The characteristics of surface waves responsible for the coastline deformation were revealed using the discriminant analysis. Conclusions. Analysis of satellite images of the spit made it possible to distinguish three periods in the history of the Bakalskaya Spit evolution: 1985–1997, 1998–2007 and 2007–2016. The first period was characterized by relative stability. The strongest erosion took place in 1998; after that the alluvial and erosion cases alternated for 10 years weakly tending to general erosion that constituted the second period. The third one that began in 2007 can be defined as the period of spit degradation accompanied by the irreversible loss of beach material. The basic parameters conditioning hydrodynamics of the Bakalskaya Spit water area are: total duration of storms; average and maximum values of significant heights of wind waves and swell. Statistical characteristics of the wind waves’ parameters are of a fairly strong inter-annual variability. According to the average and maximum indices, the wind waves directed close to the normal to the coastline (WSW and WNW) are the most developed. The applied discriminant analysis permitted to draw a statistically reliable conclusion that the direction of the final (average annual) wave impact on the coastal zone, conditioning the processes of sand accumulation or erosion was set by the waves directed to NNW, at that the swell contribution was dominant. The impact degree is conditioned by strong storms with the directions close to the normal to the coastline, namely, the WSW ones

scholarly journals Attributes of social capital in the educational organisation

Educatia 21 ◽  
2021 ◽  
pp. 144-151
Author(s):  
Mirela Minică ◽  
Keyword(s):  
Social Capital ◽  
Education Reform ◽  
Educational System ◽  
School Organization ◽  
Educational Process ◽  
Current Period ◽  
Low Degree ◽  
Degree Of Confidence ◽  
The Impact

The article highlights according to the concept of social capital, the changes generated by the COVID-19 pandemic in the educational system. This research identified the attributes of social capital at the level of the adults involved in the educational process (parents, students), the impact of the current period on them and the opinion of the respondents regarding the education reform. The conclusions of the study prove an activation of the intentions of involvement and participation in the management structures and in the educational projects at the level of the school organization, along with a low degree of confidence in the way the reform of the educational system is designed and implemented. Change management in recent years has highlighted the need for school involvement in the development of social capital and also the need to increase the role of social stakeholders in solving the challenges facing school organizations.

scholarly journals It is Fear, Not Disgust, That Enhances Memory: Experimental Study on Students in Bandung

2016 ◽  
Vol 31 (2) ◽  
pp. 77-83
Author(s):  
KaYan KaYan ◽  
Henndy Ginting ◽  
Cakrangadinata Cakrangadinata
Keyword(s):  
Experimental Study ◽  
Significant Influence ◽  
Healthy Lifestyle ◽  
Negative Emotion ◽  
Low Degree ◽  
Research Findings ◽  
The Impact ◽  
The Brain ◽  
Different Parts

A number of research findings have found the impact of emotion on memory. Some researchers stated that disgust has more impact on memory, however according to the current study the effect of fear cannot be ignored. Both disgust and fear are examples of negative emotion that may have a significant influence on behavior, such as in the attempt of creating a healthy lifestyle. The current study involved an experiment where participants were asked to memorize and recall four randomly displayed picture categories that elicit emotions of disgust, fear, joy, and neutral emotion. They also filled out a DS-R (Disgust Scale-Revised) questionnaire and a supporting questionnaire about healthy lifestyle. Analysis of the results showed that disgust did not show an effect on memory, but fear instead did. This is related to the fact that most participants showed a low degree of disgust, and so it was not considered a significant emotion that affected memory compared to fear. In addition, physiologically fear and disgust are managed by different parts of the brain and thus it was assumed that they will have a different impact on memory. The findings implied that, in campaigning for a healthier lifestyle, fear emotion need to be instilled in people.

scholarly journals Discrete approach to stochastic parametrization and dimension reduction in nonlinear dynamics

2015 ◽  
Vol 112 (32) ◽  
pp. 9804-9809 ◽  
Author(s):  
Alexandre J. Chorin ◽  
Fei Lu
Keyword(s):  
Statistical Physics ◽  
Moving Average ◽  
Nonlinear Differential Equations ◽  
Numerical Algorithms ◽  
Engineering Practice ◽  
Fully Discrete ◽  
Lorenz 96 ◽  
The Impact ◽  
Time Dependent Problems ◽  
Approximate Equations

Many physical systems are described by nonlinear differential equations that are too complicated to solve in full. A natural way to proceed is to divide the variables into those that are of direct interest and those that are not, formulate solvable approximate equations for the variables of greater interest, and use data and statistical methods to account for the impact of the other variables. In the present paper we consider time-dependent problems and introduce a fully discrete solution method, which simplifies both the analysis of the data and the numerical algorithms. The resulting time series are identified by a NARMAX (nonlinear autoregression moving average with exogenous input) representation familiar from engineering practice. The connections with the Mori–Zwanzig formalism of statistical physics are discussed, as well as an application to the Lorenz 96 system.

Electoral Distortion under STV Random Sampling Procedures

1986 ◽  
Vol 16 (2) ◽  
pp. 243-253 ◽  
Author(s):  
Michael Gallagher ◽  
A. R. Unwin
Keyword(s):  
Random Sampling ◽  
Social Choice Function ◽  
Electoral System ◽  
Approval Voting ◽  
Multi Stage ◽  
Low Degree ◽  
Degree Of Acceptance ◽  
The Republic ◽  
Sampling Procedures ◽  
The Impact

This Note will discuss the impact of random sampling at elections conducted under the single transferable vote (STV) electoral system in multi-member constituencies in the Republic of Ireland. STV, partly because of its popularity among electoral reformers, has received considerable theoretical scrutiny. It has been given an ‘intermediate’ rating in recent assessment of a number of electoral systems, and dismissed as a ‘perverse social choice function’ because it is subject to non-monotonicity. This shortcoming is also mainly responsible for the low degree of acceptance accorded to it by Brams and Fishburn. Nurmi concludes that STV (like other multi-stage systems) performs poorly, with regard to a number of criteria, in comparison with one-stage systems like approval voting. Black complains that STV ‘is a compound of minor complexities and is difficult to remember’. Others have discussed shortcomings in STV and suggested remedies which can be implemented where the counting of votes is entirely computerized.

Impact of low-degree gravity field estimation in the SLR data processing of spherical satellites at AIUB

2021 ◽  
Author(s):  
Linda Geisser ◽  
Ulrich Meyer ◽  
Daniel Arnold ◽  
Adrian Jäggi ◽  
Daniela Thaller
Keyword(s):  
Gravity Field ◽  
Lower Altitude ◽  
Earth’S Gravity Field ◽  
Low Degree ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
Field Estimation ◽  
University Of Bern ◽  
The University ◽  
The Impact

<p>The Astronomical Institute of the University of Bern (AIUB) collaborates with the Federal Agency for Cartography and Geodesy (BKG) in Germany to develop new procedures to generate products for the International Laser Ranging Service (ILRS). In this framework the SLR processing of the standard ILRS weekly solutions of spherical geodetic satellites at AIUB, where the orbits are determined in 7-day arcs together with station coordinates and other geodetic parameters, is extended from LAGEOS-1/2 and the Etalon-1/2 satellites to also include the LARES satellite orbiting the Earth at much lower altitude. Since a lower orbit experiences a more variable enviroment, e.g. it is more sensitive to time-variable Earth's gravity field, the orbit parametrization has to be adapted and also the low degree spherical harmonic coefficients of Earth's gravity field have to be co-estimated. The impact of the gravity field estimation is studied by validating the quality of other geodetic parameters such as geocenter coordinates, Earth Rotation Parameters (ERPs) and station coordinates. The analysis of the influence of LARES on the SLR solution shows that a good datum definition is important.</p>

follow-up of alumni as a strategic action in Brazilian universities

2017 ◽  
Vol 5 (12) ◽  
pp. 169-179
Author(s):  
Claudia Prim Correa ◽  
Cibele Barsalini Martins ◽  
Areli Andreia Dos Santos
Keyword(s):  
Graduate Programs ◽  
Theoretical Work ◽  
Multiple Objectives ◽  
Strategic Action ◽  
Academic Practice ◽  
Low Degree ◽  
Complex Organization ◽  
The Impact ◽  
Regular Students

In Brazilian universities, considered as the complex organization because of its multiple objectives, high specialization and low degree of coordination, the follow-up of alumni presents itself as a strategic action. The purpose of following-up alumni consists in obtaining information that enables evaluating the impact of graduate programs on the professional and academic practice of alumni, as well as enhance the qualification of regular students. Taking these aspects into consideration, in this theoretical work we discuss aspects related to Brazilian universities and the follow-up of alumni as a strategic action in this context.

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