Large-scale spatial characterization of a karst aquifer by combination of periodic and non-periodic responses (Lez aquifer, France)

2021 ◽  
Author(s):  
Pierre Fischer ◽  
Hervé Jourde
Keyword(s):  
Large Scale ◽  
Karst Aquifer ◽  
Property Values ◽  
Field Measurements ◽  
High Water ◽  
Distributed Model ◽  
Inversion Method ◽  
Spatial Characterization ◽  
The Matrix

<p>Spatial characterization of the hydraulic properties in the subsurface is an extensively studied problematic. Inverse problems allow to image those properties by interpreting the information from a dataset of field measurements with a chosen physical formulation of fluxes in a numerical distributed model. However, karst media characterization remains a complex task, due to the fact that the matrix and conduits entities generate a highly contrasted distribution of property values. Thus, one needs to employ an inversion method able to represent this contrast and also use data providing information on the localization of the conduits network and its connectivity.</p><p>We propose a large-scale 2-D application of characterization of the Lez aquifer in southern France, covering a surface of about 400 km². We take advantages of long-terms measurements within the framework of the MEDYCYSS observation site, part of the Karst observatory network (www.snokarst.org) initiated by the French institute INSU/CNRS. Drawdown signals measured in 14 wells incorporating a periodic response due to a daily pumping at the aquifers spring were thus considered for this study. The periodic responses can provide connectivity information between wells in the inversion process, while non-periodic responses will permit to better assess the large-scale property values of the whole hydrosystem. A Cellular Automata-based Deterministic Inversion (CADI) is used to generate a contrasted property field able to reproduce the measured signals in the 2-D distributed numerical model. This application is led with responses obtained at a high water-table level and also at a lower level in order to highlight the change in connectivity and flow paths mobilized at different depths.</p>

scholarly journals Hazardous substances in karst aquifer waters - one of the results of the operational monitoring of groundwater in Serbia

2020 ◽  
Vol 81 (2) ◽  
pp. 49-61
Author(s):  
Zoran Stevanovic ◽  
Veljko Marinovic ◽  
Branislav Petrovic
Keyword(s):  
Water Quality ◽  
Environmental Protection ◽  
Karst Aquifer ◽  
Colloidal Suspensions ◽  
Field Measurements ◽  
High Water ◽  
Hazardous Substances ◽  
Chemical Components ◽  
Protection Measures ◽  
Operational Monitoring

Hydrogeological survey of wider Majdanpek mining area in the Carpathian mountain arch of eastern Serbia, including open mine pits, tailings sites, and major karstic springs and caves has been undertaken in order to estimate environmental conditions in groundwater body (GWB) ?Krs?sever?, groundwater quality, and to investigate causes of their earlier indicated poor chemical status. Bearing in mind that Majdanpek copper mine field is directly bordering the karst aquifer and delineated GWB ?Krs?sever?, the two karst springs namely Valja Fundata and Kaludjerica were in situmeasured and sampled in high and low-water periods (spring 2019, late autumn 2019 and spring 2020). Sampling and analysis of groundwater were carried out under the frame of project ?Operational Monitoring of Groundwater of the Republic of Serbia?, established by the Ministry of Environmental Protection of Serbia. The field measurements of unstable chemical components and physical properties as well as laboratory analyses confirmed very poor and even hazardous water quality of both surveyed springs Valja Fundata and Kaludjerica. Registered concentrations of some ions, such as Fe2+, Mn2+, Ca2+, SO4 2?are high above maximal permitted level for potable water in Serbia. High turbidity rate also confirms impact of colloidal suspensions from the tailing which is located in karstic blind valley. Leakage of mine water passes through joints, open cavities and even large cave system Valja Fundata. Results of undertaken survey confirm that low-water period results with worse water quality and much higher concentration of hazardous substances than that characterized high-water season when infiltrated rainy water and/or melted snow dilute tailing?s wastewater. Strict application of environmental protection measures and de - sign/construction of the smaller water treatment facility at both surveyed springs should possibly mitigate the impacts of mining activities to karst groundwater and dependant ecosystem.

scholarly journals Experience of short term earthquake precursors with VLF–VHF electromagnetic emissions

2003 ◽  
Vol 3 (3/4) ◽  
pp. 217-228 ◽  
Author(s):  
K. Eftaxias ◽  
P. Kapiris ◽  
J. Polygiannakis ◽  
A. Peratzakis ◽  
J. Kopanas ◽  
...  
Keyword(s):  
Earthquake Prediction ◽  
Large Scale ◽  
Field Measurements ◽  
Short Term ◽  
Wide Range ◽  
Electromagnetic Emissions ◽  
Electro Magnetic ◽  
Focal Zone

Abstract. Electromagnetic anomalies (EMA) covering a wide range of frequencies from ULF, VLF up to VHF have been observed before recent destructive earthquakes in continental Greece. We show that the features of these signals are possibly correlated with the fault model characteristics of the associated earthquake and with the degree of geotectonic heterogeneity within the focal zone. The time evolution of these electromagnetic sequences reveals striking similarities to that observed in laboratory acoustic and electromagnetic emissions during different stages of failure preparation process in rocks. If we consider that the same dynamics governs the large-scale earthquakes and the microscopic scale sample rheological structure, the results of this analysis suggest that the recorded EMA might reflect the nucleation phase of the associated impending earthquake. We focus on the rise of the statistical view of earthquakes. We find electro-magnetic fingerprints of an underlying critical mechanism. Finally, we conclude that it is useful to combine ULF and VLF-VHF field measurements in an attempt to enhance the understanding of the physics behind these observations and thus to improve the quality of earthquake prediction. Further, the identification of an EMA as a seismogenic one supports the characterization of a sequence of shocks as foreshocks at the time they occur, further helping the earthquake prediction effort.

Spatial Characterization of the Dynamic Response of Frequencies Utilizing Structural Partition Procedure for Large-Scale Power System

2013 ◽  
Vol 14 (2) ◽  
pp. 139-148
Author(s):  
Deyou Yang
Keyword(s):  
Dynamic Response ◽  
Power System ◽  
Structural Feature ◽  
Case Studies ◽  
Network Structure ◽  
Large Scale ◽  
Fault Location ◽  
Dynamic Responses ◽  
Spatial Characterization

Abstract The aim of this paper is to present an algorithm for analysing the actual spatial characterization of the dynamic responses of frequencies for large-scale power system. Based on the distribution feature of disturbance power, the measure of interaction (MI) is employed to analyse and quantify the strength of connection among the busses and generation units. The MI takes into account the interconnection constraints among network structure and parameters. In particular, only the network parameters are used in the proposed structural partition procedure. Case Studies carried out on the IEEE 68-bus system are presented to demonstrate the application and effectiveness of the technique developed. Investigations show that the spatial characterization of the dynamic responses of frequencies can be accurately obtained with the procedure, independent of fault location and the size of disturbance, since the proposed technique is based on the structural feature of the system.

Some applications of electron beam microanalysis techniques in VLSI process evaluation

1983 ◽  
Vol 41 ◽  
pp. 160-161
Author(s):  
Simon Thomas
Keyword(s):  
Integrated Circuits ◽  
Process Evaluation ◽  
Large Scale ◽  
Technology Development ◽  
Analytical Techniques ◽  
Successful Implementation ◽  
Analysis Of Failures ◽  
Characterization Of Materials ◽  
Circuits Vlsi

Trends in the technology development of very large scale integrated circuits (VLSI) have been in the direction of higher density of components with smaller dimensions. The scaling down of device dimensions has been not only laterally but also in depth. Such efforts in miniaturization bring with them new developments in materials and processing. Successful implementation of these efforts is, to a large extent, dependent on the proper understanding of the material properties, process technologies and reliability issues, through adequate analytical studies. The analytical instrumentation technology has, fortunately, kept pace with the basic requirements of devices with lateral dimensions in the micron/ submicron range and depths of the order of nonometers. Often, newer analytical techniques have emerged or the more conventional techniques have been adapted to meet the more stringent requirements. As such, a variety of analytical techniques are available today to aid an analyst in the efforts of VLSI process evaluation. Generally such analytical efforts are divided into the characterization of materials, evaluation of processing steps and the analysis of failures.

TEM characterization of reaction zone in a SiC fiber-reinforced titanium alloy

1988 ◽  
Vol 46 ◽  
pp. 738-739
Author(s):  
G. Das ◽  
R. E. Omlor
Keyword(s):  
Titanium Alloys ◽  
Reaction Zone ◽  
Carbon Layer ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Sic Fibers ◽  
Sic Fiber ◽  
The Matrix ◽  
Immense Potential

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.

Characterization of seawater reverse osmosis fouled membranes from large scale commercial desalination plant

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Reverse Osmosis ◽  
Large Scale ◽  
Retention Rate ◽  
Local Level ◽  
Microscopic Analysis ◽  
Transmembrane Pressure ◽  
Hydraulic Permeability ◽  
Seawater Reverse Osmosis ◽  
A Chain

The objective of this work is to study the ageing state of a used reverse osmosis (RO) membrane taken in Algeria from the Benisaf Water Company seawater desalination unit. The study consists of an autopsy procedure used to perform a chain of analyses on a membrane sheet. Wear of the membrane is characterized by a degradation of its performance due to a significant increase in hydraulic permeability (25%) and pressure drop as well as a decrease in salt retention (10% to 30%). In most cases the effects of ageing are little or poorly known at the local level and global measurements such as (flux, transmembrane pressure, permeate flow, retention rate, etc.) do not allow characterization. Therefore, a used RO (reverse osmosis) membrane was selected at the site to perform the membrane autopsy tests. These tests make it possible to analyze and identify the cause as well as to understand the links between performance degradation observed at the macroscopic scale and at the scale at which ageing takes place. External and internal visual observations allow seeing the state of degradation. Microscopic analysis of the used membranes surface shows the importance of fouling. In addition, quantification and identification analyses determine a high fouling rate in the used membrane whose foulants is of inorganic and organic nature. Moreover, the analyses proved the presence of a biofilm composed of protein.

Characterization of Interconnect Defects Using Scanning Thermal Conductivity Microscopy

2004 ◽  
Author(s):  
H.W. Ho ◽  
J.C.H. Phang ◽  
A. Altes ◽  
L.J. Balk
Keyword(s):  
Thermal Conductivity ◽  
Integrated Circuits ◽  
Large Scale

Abstract In this paper, scanning thermal conductivity microscopy is used to characterize interconnect defects due to electromigration. Similar features are observed both in the temperature and thermal conductivity micrographs. The key advantage of the thermal conductivity mode is that specimen bias is not required. This is an important advantage for the characterization of defects in large scale integrated circuits. The thermal conductivity micrographs of extrusion, exposed and subsurface voids are presented and compared with the corresponding topography and temperature micrographs.

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