scholarly journals Electric charging of eruptive clouds from Shiveluch Volcano caused by different types of explosions

2019 ◽  
pp. 49-62
Author(s):  
P. P. Firstov ◽  
R. R. Akbashev ◽  
N. A. Zharinov ◽  
A. P. Maximov ◽  
T. M. Manevich ◽  
...  
Keyword(s):  
Vertical Component ◽  
Shiveluch Volcano ◽  
Electrical Field ◽  
Electrical Structure ◽  
Volcanic Monitoring ◽  
Different Types ◽  
Integrated Methods ◽  
Strong Explosion ◽  
Atmospheric Electrical Field ◽  
Positively Charged

The number of explosive eruptions at Shiveluch Volcano has significantly increased over the past years, which requires close volcanic monitoring using all available techniques. In order to implement a new monitoring technique into integrated methods of volcano monitoring, the authors analyze response to the intensity of the vertical component in the atmospheric electrical field (EZ AEF) during the movement of ash clouds. Two eruptions of different intensity that occurred December 16, 2016 and June 14, 2017 at Shiveluch were selected for study. We used a combination of satellite, seismic, and infrasound data to select signals in the EZ AEF field. Signals with negative polarity that accompanied ashfalls in the EZ AEF dynamics were registered for both eruptions within the closest area (< 50 km). In the former case, the ash cloud was “dry” and thus it caused aerial-electrical structure of the negatively charged cloud. In the latter case, a strong explosion sent into the atmosphere the large volume of ash and volcanic gases (98% in form of vapour) that resulted in the formation of a dipolar aerial-electrical structure caused by eolian differentiation within the closest area. At the distance of more than 100 km we registered a positive-going signal that is attributive to the aerial-electrical structure of the positively charged type of the cloud.

scholarly journals Electric charging of eruptive clouds from Shiveluch Volcano caused by different types of explosions

2019 ◽  
pp. 49-62
Author(s):  
P. P. Firstov ◽  
R. R. Akbashev ◽  
N. A. Zharinov ◽  
A. P. Maximov ◽  
T. M. Manevich ◽  
...  
Keyword(s):  
Vertical Component ◽  
Shiveluch Volcano ◽  
Electrical Field ◽  
Electrical Structure ◽  
Volcanic Monitoring ◽  
Different Types ◽  
Integrated Methods ◽  
Strong Explosion ◽  
Atmospheric Electrical Field ◽  
Positively Charged

The number of explosive eruptions at Shiveluch Volcano has significantly increased over the past years, which requires close volcanic monitoring using all available techniques. In order to implement a new monitoring technique into integrated methods of volcano monitoring, the authors analyze response to the intensity of the vertical component in the atmospheric electrical field (EZ AEF) during the movement of ash clouds. Two eruptions of different intensity that occurred December 16, 2016 and June 14, 2017 at Shiveluch were selected for study. We used a combination of satellite, seismic, and infrasound data to select signals in the EZ AEF field. Signals with negative polarity that accompanied ashfalls in the EZ AEF dynamics were registered for both eruptions within the closest area (< 50 km). In the former case, the ash cloud was “dry” and thus it caused aerial-electrical structure of the negatively charged cloud. In the latter case, a strong explosion sent into the atmosphere the large volume of ash and volcanic gases (98% in form of vapour) that resulted in the formation of a dipolar aerial-electrical structure caused by eolian differentiation within the closest area. At the distance of more than 100 km we registered a positive-going signal that is attributive to the aerial-electrical structure of the positively charged type of the cloud.

scholarly journals Atmospheric electrical field decrease during the <i>M = 4.1</i> Sousel earthquake (Portugal)

2011 ◽  
Vol 11 (3) ◽  
pp. 987-991 ◽  
Author(s):  
H. G. Silva ◽  
M. Bezzeghoud ◽  
A. H. Reis ◽  
R. N. Rosa ◽  
M. Tlemçani ◽  
...  
Keyword(s):  
Vertical Component ◽  
Observation Site ◽  
Electrical Field ◽  
Simple Interpretation ◽  
Earthquake Preparation ◽  
Atmospheric Electrical Field

Abstract. In this paper, we report the observation of a significant decrease of the vertical component of the atmospheric electrical field in the Évora region (Portugal) during the M = 4.1 Sousel earthquake of 27 March 2010. The epicentre of the earthquake was 52 km from the observation site, which falls within the theoretical earthquake preparation radius. A simple interpretation based on hypothetical radon emissions is presented, and future experiments required to elucidate these observations are outlined. To our knowledge, this is the first reported observation of a decrease of the atmospheric electrical field preceding an earthquake.

scholarly journals Preparation of Fe3O4-Ag Nanocomposites with Silver Petals for SERS Application

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1288
Author(s):  
Thi Thuy Nguyen ◽  
Fayna Mammeri ◽  
Souad Ammar ◽  
Thi Bich Ngoc Nguyen ◽  
Trong Nghia Nguyen ◽  
...  
Keyword(s):  
Self Assembly ◽  
Hot Spots ◽  
Surface Enhanced Raman Spectroscopy ◽  
Electrical Field ◽  
Stabilizing Agents ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Sers Sensing ◽  
Applied Electrical Field ◽  
Positively Charged

The formation of silver nanopetal-Fe3O4 poly-nanocrystals assemblies and the use of the resulting hetero-nanostructures as active substrates for Surface Enhanced Raman Spectroscopy (SERS) application are here reported. In practice, about 180 nm sized polyol-made Fe3O4 spheres, constituted by 10 nm sized crystals, were functionalized by (3-aminopropyl)triethoxysilane (APTES) to become positively charged, which can then electrostatically interact with negatively charged silver seeds. Silver petals were formed by seed-mediated growth in presence of Ag+ cations and self-assembly, using L-ascorbic acid (L-AA) and polyvinyl pyrrolidone (PVP) as mid-reducing and stabilizing agents, respectively. The resulting plasmonic structure provides a rough surface with plenty of hot spots able to locally enhance significantly any applied electrical field. Additionally, they exhibited a high enough saturation magnetization with Ms = 9.7 emu g−1 to be reversibly collected by an external magnetic field, which shortened the detection time. The plasmonic property makes the engineered Fe3O4-Ag architectures particularly valuable for magnetically assisted ultra-sensitive SERS sensing. This was unambiguously established through the successful detection, in water, of traces, (down to 10−10 M) of Rhodamine 6G (R6G), at room temperature.

Measurement of small variations of atmospheric electrical field signals in fair weather

1999 ◽  
Vol 125 (4) ◽  
pp. 34-42
Author(s):  
Ken'Ichi Narita ◽  
Nobunao Takeuchi ◽  
Noriyoshi Chubachi ◽  
Noriyasu Honma
Keyword(s):  
Fair Weather ◽  
Electrical Field ◽  
Atmospheric Electrical Field

Consistency of the strontium transport parameters in Boom Clay obtained from different types of migration experiments

2009 ◽  
Vol 1193 ◽  
Author(s):  
Marc Aertsens ◽  
Norbert Maesa ◽  
Marc Van Gompel
Keyword(s):  
Water Concentration ◽  
Transport Parameters ◽  
Electrical Field ◽  
Boom Clay ◽  
Linear Sorption ◽  
Different Types ◽  
Apparent Diffusion ◽  
Through Diffusion ◽  
Accessible Porosity

AbstractThe consistency of migration parameters obtained by different methods is examined for strontium in Boom Clay. In addition to a previous in-situ percolation experiment and electromigration experiments (using an electrical field as driving force), a lab percolation test and two through-diffusion tests (on clay cores of different lengths) have been performed.All experiments lead to a robust value for the apparent diffusion coefficient of strontium between 5 ? 10−12m2/s and 1 ? 10−11m2/s.No reliable value is obtained for the product ηR of the diffusion accessible porosity and theretardation factor R. For one of the through-diffusion experiments, the concentration decrease inthe inlet as a function of time was fitted simultaneously with the strontium profile in the clay,leading to a ηR value around 400. Estimating ηR at the inlet/clay interface as the ratio of thebulk concentration and the pore water concentration leads to a similar value. The valuesobtained from the strontium profiles in the percolation and electromigration experiments are inline as well. However, fitting for both through-diffusion tests the outlet concentrations versustime leads to very low and unrealistic values of ηR (0.15 and 0.5).Modeling shows that the transport of strontium in Boom Clay cannot be satisfactorilydescribed with the current assumptions (like e.g. instantaneous linear sorption equilibrium andboundary conditions), meaning that there is a problem to obtain a reliable value for the product ηR for strontium in Boom Clay.

scholarly journals Methods of Tree Appraisal: A Review of Their Features and Application Possibilities

2012 ◽  
Vol 38 (4) ◽  
pp. 130-140
Author(s):  
M.A. Grande-Ortiz ◽  
E. Ayuga-Téllez ◽  
M.L. Contato-Carol
Keyword(s):  
Mixed Method ◽  
Parametric Method ◽  
Economic Value ◽  
Hedonic Pricing ◽  
Urban Trees ◽  
Different Types ◽  
Hedonic Pricing Method ◽  
Integrated Methods ◽  
Basic Functions ◽  
Location Type

Urban trees perform a number of basic functions related to the environment and the welfare of city dwellers (ecological, recreational, psychological), although their benefits are not readily quantifiable. However, in certain situations, it is essential to assign an economic value to the trees. There are currently various methods for valuing the benefits of trees and greenspaces in human settlements, including statistical methods, the travel cost method, contingent valuation, the hedonic pricing method, and integrated methods. However, these methods are not used in official valuations of urban trees; in these cases, appraisal methods are used. The aim of this paper is to study the appraisal methods used for their detailed features and the possibilities of their application. The main conclusion of this review is that there are a number of methods with different types of application. The best method is selected according to tree location, type of land ownership, and the availability of data. Methods with a higher degree of applicability are CTLA, a parametric method of low difficulty, and Contato, a mixed method of medium difficulty. In any case, it is advisable to increase efforts to objectify the correction index in the case of parametric and mixed methods.

scholarly journals Nanosilica-Based Loss Circulation Composition to Cure Moderate to Severe Losses

2021 ◽  
Vol 143 (10) ◽  
Author(s):  
Vikrant Wagle ◽  
Rajendra Kalgaonkar ◽  
Abdullah AlYami ◽  
Sara AlKhalaf
Keyword(s):  
Particle Size ◽  
Particle Sizes ◽  
Activator Concentration ◽  
Surface Charges ◽  
Shear Rates ◽  
Different Types ◽  
Different Temperatures ◽  
Gelling Time ◽  
Chemical Activator ◽  
Positively Charged

Abstract The loss circulation composition comprising a combination of a nanoparticle-based dispersion and a chemical activator has been designed to treat moderate to severe losses. The nanomaterial used is an environmentally friendly nanosilica-based dispersion. The composition is designed to give delayed gelling of the nanoparticle-based dispersion. A major advantage of this technology is its ability to place the composition into the target loss circulation zone before the nanoparticle-based dispersion gels up. Premature gelling of the nanoparticle-based dispersion would avoid premature setting of the treatment fluid before it reaches the target zone. The newly developed system can be used effectively up to 300 °F. In this paper, experiments have been performed with three different types of nanoparticles differing in their surface charges and particle sizes. Two negatively charged nanoparticle-based dispersions with a particle size of 5 nm and 17 nm, respectively, and one positively charged nanoparticle-based dispersion with a particle size greater than 17 nm have been evaluated as loss circulation materials. Two different types of chemical activators, one organic and the other inorganic, have been used in this study, and their effect on the gelling time has been evaluated. The gelling time experiments have been done at four different temperatures viz. 150 °F, 200 °F, 250 °F, and 300 °F. The effect of activator concentration and different shear rates on the gelling time of the three nanoparticle-based dispersions has been studied. Permeability plugging tests have been performed using 2 mm slotted disks to evaluate the effectiveness in controlling moderate to severe losses.

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