Thermal evolution of silicic magma chambers after basalt replenishments

2000 ◽  
Vol 91 (1-2) ◽  
pp. 47-60 ◽  
Author(s):  
Takehiro Koyaguchi ◽  
Katsuya Kaneko
Keyword(s):  
Magma Chamber ◽  
Thermal Evolution ◽  
Bulk Composition ◽  
Thermal Fluctuations ◽  
Silicic Magma ◽  
Magma Chambers ◽  
Solid States ◽  
Liquid Part ◽  
Two Stages

In order to understand the governing factors of petrological features of erupted magmas of island-arc or continental volcanoes, thermal fluctuations of subvolcanic silicic magma chambers caused by intermittent basalt replenishments are investigated from the theoretical viewpoint. When basaltic magmas are repeatedly emplaced into continental crust, a long-lived silicic magma chamber may form. A silicic magma chamber within surrounding crust is composed of crystal-melt mixtures with variable melt fractions. We define the region which behaves as a liquid in a mechanical sense (‘liquid part’) and the region which is in the critical state between liquid and solid states (‘mush’) collectively as a magma chamber in this study. Such a magma chamber is surrounded by partially molten solid with lower melt fractions. Erupted magmas are considered to be derived from the liquid part. The size of a silicic magma chamber is determined by the long-term balance between heat supply from basalt and heat loss by conduction, while the temperature and the volume of the liquid part fluctuate in response to individual basalt inputs. Thermal evolution of a silicic magma chamber after each basalt input is divided into two stages. In the first stage, the liquid part rapidly propagates within the magma chamber by melting the silicic mush, and its temperature rises above and decays back to the effective fusion temperature of the crystal-melt mixture on a short timescale. In some cases the liquid part no longer exists. In the second stage, the liquid part ceases to propagate and cools slowly by heat conduction on a much longer timescale. The petrological features of the liquid part, such as the amount of unmelted preexisting crystals, depend on the intensity of individual pulses of the basalt heat source and the degree of fractionation during the first stage, as well as the bulk composition of the silicic magma.

scholarly journals The influence of bulk composition on the long-term interior-atmosphere evolution of terrestrial exoplanets

2020 ◽  
Vol 643 ◽  
pp. A44
Author(s):  
Rob J. Spaargaren ◽  
Maxim D. Ballmer ◽  
Dan J. Bower ◽  
Caroline Dorn ◽  
Paul J. Tackley
Keyword(s):  
Plate Tectonics ◽  
Thermal Evolution ◽  
Bulk Composition ◽  
Dynamic Regime ◽  
Evolution Model ◽  
Terrestrial Planets ◽  
Temperature Structure ◽  
Geological Time ◽  
Near Surface

Aims. The secondary atmospheres of terrestrial planets form and evolve as a consequence of interaction with the interior over geological time. We aim to quantify the influence of planetary bulk composition on the interior–atmosphere evolution for Earth-sized terrestrial planets to aid in the interpretation of future observations of terrestrial exoplanet atmospheres. Methods. We used a geochemical model to determine the major-element composition of planetary interiors (MgO, FeO, and SiO2) following the crystallization of a magma ocean after planet formation, predicting a compositional profile of the interior as an initial condition for our long-term thermal evolution model. Our 1D evolution model predicts the pressure–temperature structure of the interior, which we used to evaluate near-surface melt production and subsequent volatile outgassing. Volatiles are exchanged between the interior and atmosphere according to mass conservation. Results. Based on stellar compositions reported in the Hypatia catalog, we predict that about half of rocky exoplanets have a mantle that convects as a single layer (whole-mantle convection), and the other half exhibit double-layered convection due to the presence of a mid-mantle compositional boundary. Double-layered convection is more likely for planets with high bulk planetary Fe-content and low Mg/Si-ratio. We find that planets with low Mg/Si-ratio tend to cool slowly because their mantle viscosity is high. Accordingly, low-Mg/Si planets also tend to lose volatiles swiftly through extensive melting. Moreover, the dynamic regime of the lithosphere (plate tectonics vs. stagnant lid) has a first-order influence on the thermal evolution and volatile cycling. These results suggest that the composition of terrestrial exoplanetary atmospheres can provide information on the dynamic regime of the lithosphere and the thermo-chemical evolution of the interior.

Analysis of Long-Term and Thermal Cycling Tests for a Commercial Solid Oxide Fuel Cell

2017 ◽  
Vol 14 (4) ◽  
Author(s):  
Dustin Lee ◽  
Jing-Kai Lin ◽  
Chun-Huang Tsai ◽  
Szu-Han Wu ◽  
Yung-Neng Cheng ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Thermal Cycling ◽  
Solid Oxide Fuel Cell ◽  
Coefficient Of Thermal Expansion ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Flow Rates ◽  
Degradation Rates ◽  
Two Stages

The effects of isothermally long-term and thermal cycling tests on the performance of an ASC type commercial solid oxide fuel cell (SOFC) have been investigated. For the long-term test, the cells were tested over 5000 h in two stages, the first 3000 h and the followed 2000 h, under the different flow rates of hydrogen and air. Regarding the thermal cycling test, 60 cycles in total were also divided into two sections, the temperature ranges of 700 °C to 250 °C and 700 °C to 50 °C were applied for the every single cycle of first 30 cycles and the later 30 cycles, respectively. The results of long-term test show that the average degradation rates for the cell in the first 3000 h and the followed 2000 h under different flow rates of fuel and air are 1.16 and 2.64%/kh, respectively. However, there is only a degradation of 6.6% in voltage for the cell after 60 thermal cycling tests. In addition, it is found that many pores formed in the anode of the cell which caused by the agglomeration of Ni after long-term test. In contrast, the vertical cracks penetrating through the cathode of the cell and the in-plane cracks between the cathode and barrier layer of the cell formed due to the coefficient of thermal expansion (CTE) mismatch after 60 thermal cycling tests.

scholarly journals Greater soil carbon stocks and faster turnover rates with increasing agricultural productivity

SOIL ◽  
2017 ◽  
Vol 3 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Jonathan Sanderman ◽  
Courtney Creamer ◽  
W. Troy Baisden ◽  
Mark Farrell ◽  
Stewart Fallon
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Sugar Content ◽  
Bulk Composition ◽  
Agricultural Productivity ◽  
Carbon Stocks ◽  
Decay Rates ◽  
Turnover Rates ◽  
Soil Carbon Stocks

Abstract. Devising agricultural management schemes that enhance food security and soil carbon levels is a high priority for many nations. However, the coupling between agricultural productivity, soil carbon stocks and organic matter turnover rates is still unclear. Archived soil samples from four decades of a long-term crop rotation trial were analyzed for soil organic matter (SOM) cycling-relevant properties: C and N content, bulk composition by nuclear magnetic resonance (NMR) spectroscopy, amino sugar content, short-term C bioavailability assays, and long-term C turnover rates by modeling the incorporation of the bomb spike in atmospheric 14C into the soil. After > 40 years under consistent management, topsoil carbon stocks ranged from 14 to 33 Mg C ha−1 and were linearly related to the mean productivity of each treatment. Measurements of SOM composition demonstrated increasing amounts of plant- and microbially derived SOM along the productivity gradient. Under two modeling scenarios, radiocarbon data indicated overall SOM turnover time decreased from 40 to 13 years with increasing productivity – twice the rate of decline predicted from simple steady-state models or static three-pool decay rates of measured C pool distributions. Similarly, the half-life of synthetic root exudates decreased from 30.4 to 21.5 h with increasing productivity, indicating accelerated microbial activity. These findings suggest that there is a direct feedback between accelerated biological activity, carbon cycling rates and rates of carbon stabilization with important implications for how SOM dynamics are represented in models.

scholarly journals Cost Effectual Distributed Cooperative Cluster based Communication Protocol in Wireless Sensor Network

2020 ◽  
Vol 8 (6) ◽  
pp. 5652-5656
Keyword(s):  
Communication Protocol ◽  
Wireless Sensor ◽  
Team Leaders ◽  
Great Strength ◽  
Second Stage ◽  
Remote Sensor ◽  
Channel Distortion ◽  
Two Stages ◽  
Intense Research

Theoretical energy recognition in remote sensor systems has received intense research interest in the late years. Radio variation, channel distortion, and blockage bring great strength and responsiveness to packets broadcast over a remote channel. A twin innovation is effective communication that can drastically increase the channel range and reduce transmission vigor consumption in disrupting channel. Growth in the direct range brings with it a reduced fault rate. In this paper, an acceptable correspondence method is proposed for each tab with active sending and receiving clusters. It consists of two stages, the precise routing phase, the selective and transmitting stage. In the routing phase, the basic route between the source and the sink hub is started. In the second stage, centers of fundamental development toward flattering team leaders select additional touch centers with minimal biomass costs from their surroundings, and then spread from bundle to cluster to the recently established endurance cluster. Reductions in error rate and regeneration are proven by the fact that malpractice funds become long-term obligation systems.

scholarly journals Competitiveness analysis of Czech agrarian foreign trade in the context of world agrarian market and agrarian trade of EU-27 countries

2010 ◽  
Vol 58 (6) ◽  
pp. 503-514
Author(s):  
Miroslav Svatoš ◽  
Luboš Smutka
Keyword(s):  
World Market ◽  
View Point ◽  
Eu Countries ◽  
Bcg Matrix ◽  
The World ◽  
Comparative Advantages ◽  
Two Stages ◽  
Balassa Index ◽  
The Eu

This paper analyses the commodity structure of Czech (CR) agrarian trade in relation to the EU countries. An emphasis is put on comparative advantages of particular aggregations from the view-point of their application on the EU internal market. This analysis is based on an evaluation of comparative advantages by means of a modified Balassa index. It is studied in two stages, for the internal EU market and the world market. The analysis results are then shown in a graph. Subsequently, the authors implement an idea arising from a BCG matrix on the results of the graphic presentation. The aim is to identify those aggregations (SITC, rev. 3) which are or have a potential to be a pillar of agri-business (ie, the “cash cows” and “stars”), and vice versa to show the aggregation which are non-prospective in the long term or problematic (ie, the “dogs” and “problem children”). As start are identified as those aggregations which are characterised by the highest growth rate of comparative advantage value. From the analysis results, changes are apparent if we compare the CR trade commodity structure in relation to the EU countries. Findings also concern the development of comparative advantages and following CR specialisation on trade with certain aggregations.

scholarly journals Slow-release fertilizers and possibilities of their utilizing in nursery

2004 ◽  
Vol 52 (2) ◽  
pp. 155-164
Author(s):  
Petr Salaš
Keyword(s):  
Slow Release ◽  
Ornamental Plants ◽  
Woody Species ◽  
Soil Surface ◽  
Berberis Thunbergii ◽  
Slow Release Fertilizers ◽  
Picea Omorika ◽  
One Year ◽  
Two Stages

Reserve, slow-release fertilizers (SRF) enable to simplify the whole system of plant nutrition and fertilisation. Tabletted fertilizers of the Silvamix series represent a prospective product of Czech provenience. At our university, these fertilizers have been tested and used since the year 1991. Ornamental woody species grown in containers were investigated in two stages. Experiments with ornamental plants were established using one-year-old cuttings and seedlings of the following deciduous and evergreen woody species:Cotoneaster dammeri Skogholm,Berberis thunbergii,Potentilla fruticosa Snowflake,Ligustrum vulgare AtrovirensandPicea omorika. After planting into containers, fertilizers in the dose of 1 tablet (i.e. 10 g) per litre of substrate were applied either to roots level or on the soil surface in the container. Silvamix in the dose of 5 g.l-1was used as the tested fertilizer in the second stage. It was applied during the planting in the form of tablets and/or a powder. Control plants were fertilized in the course of growing season using a common agricultural fertilizer Cererit Z. The annual plants increments were measured. These experiments demonstrated a long-term optimum effect of this product on woody species and an equal quality and efficiency of its tabletted and powdered forms.

Towards a Renewed Vision of Imperial Authority

2019 ◽  
pp. 237-269
Author(s):  
Florin Leonte
Keyword(s):  
Fourteenth Century ◽  
Political Communication ◽  
The West ◽  
Substantial Body ◽  
Political Messages ◽  
Imperial Authority ◽  
Second Stage ◽  
Two Stages

The chapter discusses how Manuel Palaiologos’ texts reveal not only the emperor’s standpoints in his attempts to answer political challenges, but also a long-term imperial project that sought to establish a system of effective political communication by exhibiting his fatherly concern for his son and co-emperor. This project involved two stages with changing approaches. In the first stage, the emperor strengthened his connections with the literati and frequently chaired theatra. The letters and the dialogic mode of his text on marriage point to the fact that during the last decade of the fourteenth century, the emperor did not have at his disposal too many possibilities of circulating his political messages except for the rather informal meetings in the framework of theatra. In a second stage, which chronologically coincided with the years following the emperor’s return from the West, Manuel attempted to consolidate his ruling position by highlighting in the Foundations and the Orations that he appointed his son, John, as successor. In the absence of a more substantial body of court rhetoricians, the emperor undertook the role of a social-political commentator and accordingly put forward a personal discourse on imperial authority.

scholarly journals Thermal evolution and quiescent emission of transiently accreting neutron stars

2019 ◽  
Vol 629 ◽  
pp. A88 ◽  
Author(s):  
A. Y. Potekhin ◽  
A. I. Chugunov ◽  
G. Chabrier
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Nuclear Reactions ◽  
Thermal Evolution ◽  
Theoretical Models ◽  
Equilibrium Temperature ◽  
Theoretical Interpretation ◽  
Quasi Equilibrium ◽  
Accretion Rates

Aims. We study the long-term thermal evolution of neutron stars in soft X-ray transients (SXTs), taking the deep crustal heating into account consistently with the changes of the composition of the crust. We collect observational estimates of average accretion rates and thermal luminosities of such neutron stars and compare the theory with observations. Methods. We performed simulations of thermal evolution of accreting neutron stars, considering the gradual replacement of the original nonaccreted crust by the reprocessed accreted matter, the neutrino and photon energy losses, and the deep crustal heating due to nuclear reactions in the accreted crust. We also tested and compared results for different modern theoretical models. We updated a compilation of the observational estimates of the thermal luminosities in quiescence and average accretion rates in the SXTs and compared the observational estimates with the theoretical results. Results. The long-term thermal evolution of transiently accreting neutron stars is nonmonotonic. The quasi-equilibrium temperature in quiescence reaches a minimum and then increases toward the final steady state. The quasi-equilibrium thermal luminosity of a neutron star in an SXT can be substantially lower at the minimum than in the final state. This enlarges the range of possibilities for theoretical interpretation of observations of such neutron stars. The updates of the theory and observations leave the previous conclusions unchanged, namely that the direct Urca process operates in relatively cold neutron stars and that an accreted heat-blanketing envelope is likely present in relatively hot neutron stars in the SXTs in quiescence. The results of the comparison of theory with observations favor suppression of the triplet pairing type of nucleon superfluidity in the neutron-star matter.

Sign in / Sign up

Export Citation Format

Share Document