scholarly journals Influence of permeability on the hydrothermal system at Vulcano Island (Italy): inferences from numerical simulations

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Santina Chiara Stissi ◽  
Rosalba Napoli ◽  
Gilda Currenti ◽  
Andrey Afanasyev ◽  
Giordano Montegrossi
Keyword(s):  
Numerical Simulations ◽  
Fluid Transport ◽  
Hydrothermal Systems ◽  
Vulcano Island ◽  
Temporal Correlations ◽  
Geophysical Model ◽  
Complex Interactions ◽  
Volcano Seismicity ◽  
Medium Permeability ◽  
Permeability Distribution

AbstractVolcano-hydrothermal systems are governed by complex interactions between fluid transport, and geochemical and mechanical processes. Evidence of this close interplay has been testified by distinct spatial and temporal correlations in geochemical and geophysical observations at Vulcano Island (Italy). To understand the interaction between fluid circulation and the geochemical and geophysical manifestations, we perform a parametric study to explore different scenarios by implementing a hydro-geophysical model based on the equations for heat and mass transfer in a porous medium and thermo-poroelastic theory. Numerical simulations allow us to define the controlling role of permeability distribution on the different modeled parameters as well as on the geophysical observables. Changes in the permeability within the highly fractured crater area could be responsible for the fluctuations in gas emission and temperature recorded during the crisis periods, which are accompanied by shallow volcano-seismicity in the absence of significant deformation and gravity variations. Despite the general medium permeability of the volcanic edifice, the presence of more highly permeable pathways, which allow the gas to rapidly escape, as testified by the presence of a well-developed fumarolic field, prevents the pressure buildup at shallow depths. Graphic abstract

Critical Zone Observatories: Building a network to advance interdisciplinary study of Earth surface processes

2008 ◽  
Vol 72 (1) ◽  
pp. 7-10 ◽  
Author(s):  
S. P. Anderson ◽  
R. C. Bales ◽  
C. J. Duffy
Keyword(s):  
Fluid Transport ◽  
Spatial Scales ◽  
Critical Zone ◽  
Watershed Scale ◽  
Spatial And Temporal Scales ◽  
Complex Interactions ◽  
Tectonic Processes ◽  
Interdisciplinary Approaches ◽  
Dynamic Interface ◽  
Interdisciplinary Study

AbstractWe live at the dynamic interface between the solid Earth and its outer fluid envelopes. This interface, extending from the outer vegetation canopy to the base of active groundwater, was recently named the Critical Zone because it supports life and is increasingly impacted by human actions. Understanding the complex interactions between processes that operate in and shape the Critical Zone requires interdisciplinary approaches that span wide spatial and temporal scales. Tectonic processes, weathering, fluid transport, and biological processes control the function and structure of the Critical Zone. Three Critical Zone Observatories recently established by the U.S. National Science Foundation are designed to integrate studies of process interactions up to the watershed scale. A goal of the program is to build the three independently conceived observatories into a network from which broader understanding — larger spatial scales but also deeper insight — can emerge.

Detection and monitoring of hydrothermal alteration by Principal Component Analysis applied on UAS derived optical data, Vulcano Island - Italy

2021 ◽  
Author(s):  
Daniel Müller ◽  
Stefan Bredemeyer ◽  
Edgar Zorn ◽  
Erica De Paolo ◽  
Thomas Walter
Keyword(s):  
Principal Component Analysis ◽  
High Resolution ◽  
Hydrothermal Alteration ◽  
High Efficiency ◽  
Principal Component ◽  
Component Analysis ◽  
Hydrothermal Systems ◽  
Unmanned Aircraft ◽  
Optical Data ◽  
Vulcano Island

<p>Modern UAS (unmanned aircraft system), light weight sensor systems and new processing routines allow us to gather optical data of volcanoes at a high resolution. However, due to the typically poor colorization, our ability to investigate and interpret such data is limited. Further, the information stored in the red, green and blue channel (RGB) is correlated. This makes any analysis a 3 dimensional task. Principal Component Analysis (PCA) helps us to overcome these problems by decorrelating the original band information and generating a variance representation of the original data. Therefore PCA is a suitable tool to detect optical anomalies, as might be caused by volcanic degassing and associated processes.</p><p>Applied in a case study at La Fossa Cone (Vulcano Island - Italy), the PCA showed a high efficiency for the detection and pixel based extraction of areas subject to hydrothermal alteration and sulfur deposition. We observed a broad alteration zone surrounding the active fumarole field, but also heterogeneities within, indicating a segmentation. Systematic variations in color and density distribution of sulfur deposits have implications for structural controls on the degassing system.</p><p>Combining the efficiency of PCA with the high resolution of UAS derived data, this methodology has a high potential to be employed in the spatio-temporal monitoring of volcanic hydrothermal systems and processes at surface.</p><p> </p>

scholarly journals The effect of compressibility on the behaviour of filter media

2020 ◽  
Vol 85 (4) ◽  
pp. 564-583
Author(s):  
Jakub Köry ◽  
Armin U Krupp ◽  
Colin P Please ◽  
Ian M Griffiths
Keyword(s):  
Porous Material ◽  
Material Properties ◽  
Pressure Difference ◽  
Side Effect ◽  
Fluid Transport ◽  
Applied Pressure ◽  
Filter Media ◽  
Fluid Flux ◽  
Permeability Distribution

Abstract A filter comprises porous material that traps contaminants when fluid passes through under an applied pressure difference. One side effect of this applied pressure, however, is that it compresses the filter. This changes the permeability, which may affect its performance. As the applied pressure increases, the flux of fluid processed by the filter will also increase but the permeability will decrease. Eventually, the permeability reaches zero at a point in the filter and the fluid flux falls to zero. In this paper, we derive a model for the fluid transport through a filter due to an applied pressure difference and the resulting compression. We use this to determine the maximum operating flux that can be achieved without the permeability reaching zero and the filter shutting down. We determine the material properties that balance the desire to maximize flux while minimizing power use. We also show how choosing an initial spatially dependent permeability can lead to a uniformly permeable filter under operation and we find the permeability distribution that maximizes the flux for a given applied pressure, both of which have desirable industrial implications. The ideas laid out in this paper set a framework for modelling more complex scenarios such as filter blocking.

scholarly journals Validity domains and parametrizations for white-noise and multiscale models in turbulence and wave-turbulence interactions

2021 ◽  
Author(s):  
valentin resseguier ◽  
Erwan Hascoet ◽  
Bertrand Chapron ◽  
Baylor Fox-Kemper
Keyword(s):  
Numerical Simulations ◽  
Fluid Transport ◽  
Parametric Models ◽  
Small Scale ◽  
Numerical Representation ◽  
Spatial Correlations ◽  
Self Similarity ◽  
Fluid Velocities ◽  
Wide Range ◽  
Spatio Temporal

<p>Geophysical fluid dynamics systems generally involve a wide range of spatio-temporal scales. Numerical representation can only simulate some of the scales. The others, at the unresolved scales of motion, must be parameterized for each type of phenomenon (wave, eddy, current), in terms of expected effects on the resolved scales. Most developments then assume that the fluid transport velocity has a time-uncorrelated noisy component with zero mean and stationary statistics. These approximations generally simplify theoretical descriptions, numerical simulations, data comparisons or more recently model error quantifications for data assimilation.</p><p>In the present work, we will discuss the applicability of such approximations through two examples: a surface oceanic current dynamics and swell refractions by surface currents.</p><p>When the time-decorrelation assumption is valid, we propose simple and tuning-free parametric models to represent the spatial correlations of the white-in-time small-scale velocity to help simulate the geophysical system of interest. These parametric models relies on turbulence space self-similarity and their statistical properties (e.g. spectral slope) can be easily estimated from observations of larger scale fluid velocities.</p><p>When the white-in-time approximation is not valid, we extend the previous parametric models to follow self-similarity properties in both time and space.</p><p>Numerical simulations will illustrate these theoretical developments along the presentation.</p>

scholarly journals Phylogenetic Diversity of Archaea in Shallow Hydrothermal Vents of Eolian Islands, Italy

Diversity ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 156 ◽  
Author(s):  
Concetta Gugliandolo ◽  
Teresa L. Maugeri
Keyword(s):  
Hydrothermal Vents ◽  
Inorganic Compounds ◽  
Archaeal Community ◽  
Hydrothermal Systems ◽  
Rrna Gene ◽  
Microbial Composition ◽  
Vulcano Island ◽  
High Concentrations ◽  
Shallow Hydrothermal Vents ◽  
The 16S Rrna Gene

Shallow hydrothermal systems (SHS) around the Eolian Islands (Italy), related to both active and extinct volcanism, are characterized by high temperatures, high concentrations of CO2 and H2S, and low pH, prohibitive for the majority of eukaryotes which are less tolerant to the extreme conditions than prokaryotes. Archaea and bacteria are the key elements for the functioning of these ecosystems, as they are involved in the transformation of inorganic compounds released from the vent emissions and are at the basis of the hydrothermal system food web. New extremophilic archaea (thermophilic, hyperthermophilic, acidophilic, alkalophilic, etc.) have been isolated from vents of Vulcano Island, exhibiting interesting features potentially valuable in biotechnology. Metagenomic analyses, which mainly involved molecular studies of the 16S rRNA gene, provided different insights into microbial composition associated with Eolian SHS. Archaeal community composition at Eolian vent sites results greatly affected by the geochemistry of the studied vents, principally by hypersaline conditions and declining temperatures. Archaeal community in sediments was mostly composed by hyperthermophilic members of Crenarchaeota (class Thermoprotei) and Euryarchaeota (Thermococci and Methanococci) at the highest temperature condition. Mesophilic Euryarchaeota (Halobacteria, Methanomicrobia, and Methanobacteria) increased with decreasing temperatures. Eolian SHS harbor a high diversity of largely unknown archaea, and the studied vents may be an important source of new isolates potentially useful for biotechnological purposes.

scholarly journals Spatio-temporal correlations between catastrophe events in a microtubule bundle: a computational study

2019 ◽  
Author(s):  
Makarand Diwe ◽  
Manoj Gopalakrishnan
Keyword(s):  
Stochastic Model ◽  
Numerical Simulations ◽  
Growth Velocity ◽  
Computational Study ◽  
Microtubule Bundle ◽  
One Dimensional ◽  
Temporal Correlations ◽  
Diffusion Limited ◽  
Spatio Temporal

AbstractWe explore correlations between dynamics of different microtubules in a bundle, via numerical simulations, using a one-dimensional stochastic model of a microtubule. The GTP-bound tubulins undergo diffusion-limited binding to the tip. Random hydrolysis events take place along the filament, and converts GTP-tubulin to GDP-tubulin. The filament starts depolymerising when the monomer at the tip becomes GDP-bound; in this case, detachment of GDP-tubulin ensues and continues until either GTP-bound tubulin is exposed or complete depolymerisation is achieved. In the latter case, the filament is defined to have undergone a “catastrophe”. Our results show that, in general, the dynamics of growth and catastrophe in different filaments are coupled to each other; closer the filaments are, the stronger the coupling. In particular, all filaments grow slower, on average, when brought closer together. The reduction in growth velocity also leads to more frequent catastrophes. More dramatically, catastrophe events in the different filaments forming a bundle are found to be correlated; a catastrophe event in one filament is more likely to be followed by a similar event in the same filament. This propensity of bunching disappears when the filaments move farther apart.

Where’s the fat? Freeze-fracture analysis of ingredient interactions in food systems

1993 ◽  
Vol 51 ◽  
pp. 48-49
Author(s):  
Jean Fincher
Keyword(s):  
Lipid Droplets ◽  
Food Systems ◽  
Food Industry ◽  
Freeze Fracture ◽  
Food Science ◽  
Complex Interactions ◽  
Fat Reduction ◽  
Important Trend ◽  
Conventional Foods ◽  
Whipped Cream

An important trend in the food industry today is reduction in the amount of fat in manufactured foods. Often fat reduction is accomplished by replacing part of the natural fat with carbohydrates which serve to bind water and increase viscosity. It is in understanding the roles of these two major components of food, fats and carbohydrates, that freeze-fracture is so important. It is well known that conventional fixation procedures are inadequate for many food products, in particular, foods with carbohydrates as a predominant structural feature. For some food science applications the advantages of freeze-fracture preparation procedures include not only the avoidance of chemical fixatives, but also the opportunity to control the temperature of the sample just prior to rapid freezing.In conventional foods freeze-fracture has been used most successfully in analysis of milk and milk products. Milk gels depend on interactions between lipid droplets and proteins. Whipped emulsions, either whipped cream or ice cream, involve complex interactions between lipid, protein, air cell surfaces, and added emulsifiers.

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