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gonca ahi

Hacettepe University, Geomatics Engineering, Faculty Member

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Address: Ankara, Ankara, Turkey

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Istanbul Technical University

Yuri Tarasevich

Astrakhan State University

Hacettepe University

Julius-Maximilians - Universität Würzburg

Mohd Hariri Arifin

National University of Malaysia

Istanbul University

NIT RAIPUR

Michael Kennedy

Midlands Technical College

ANDERS VEST CHRISTIANSEN

Aarhus University

University of East London

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Papers by gonca ahi

Characterization of heterogeneities in clay-rocks using electrical methods

Geoelectrical Characterization of the Excavation Disturbed Zone (EDZ) in the experimental platform of Tournemire

Zaman ve Spektral IP Yöntemi ile Killi Kayaçlardaki Dokusal ve Su İçeriğiyle İlişkili Heterojenitelerin Belirlenmesi

Structural characterization of the disturbed zone in the argillaceous Tournemire platform with timedomain induced polarization method

Effective medium approaches to model spectral IP responses in soils: Impact of microstructure, EEGS NSGS Workshop on Induced Polarization: Research and Recent Advances in Near Surface Applications

JNGG 2010 pp 867-874 Okay

Modelling the induced polarization of bentonite-sand mixtures

Modelling the induced polarization of bentonite-sand mixtures. 3rd International Workshop on Indu... more Modelling the induced polarization of bentonite-sand mixtures. 3rd International Workshop on Induced Polarization, Apr 2014, Ile d'Oléron, France. 2 p. HAL Id: hal-00959864 https://hal-brgm.archives-ouvertes.fr/hal-00959864 Submitted on 17 Mar 2014 HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt e a la diffusion de documents scientifiques de niveau recherche, publiés ou non emanant de etablissements d'enseignement et de recherche français oú etrangers, des laboratoires publics ou privés.

Experimental investigation of the SIP response of saturated clay-sand mixtures: impact of the clay mineralogy

Caractérisation géoélectrique de la zone endommagée des galeries sur le site de Tournemire

Characterization of Excavation Damaged Zone and its structural heterogeneities with Time and Spectral IP methods

International Geophysical Conference and Oil & Gas Exhibition, Istanbul, Turkey, 17-19 September 2012, 2012

Thestreamlined synthesis of compounds with wide spectrum of essential properties is prospective l... more Thestreamlined synthesis of compounds with wide spectrum of essential properties is prospective lines of development of chemistry of nitrogen containing heterocyclic compounds. Triazines hold a specific place among the great variety of nitrogen containing heterocyclic compounds. Derivatives of unsymmetrical triazines demonstrate a large range of bioactive action, they were offered in the quality of herbicides, plant growth regulators, insecticides, antifungal, acaricide, pharmaceutical and veterinary preparations, stabilizer-antioxygen of polymers and also as corrosion inhibitor. Compounds of 1,2,4-triazinones series are widely reported in the publications, but unsymmetrical triazines particularly their acyl and amino derivatives haven't been studied detailed. Especially there are not many articles about route for the synthesis of acyl and amino

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

GEOPHYSICS, 2014

Spectral induced polarization or complex conductivity is a promising electric method in hydrogeop... more Spectral induced polarization or complex conductivity is a promising electric method in hydrogeophysics because of its sensitivity to water saturation, permeability, and particle size distribution (PSD). However, the physical and chemical mechanisms that generate the low-frequency complex conductivity of clays are still debated. To explain these mechanisms, the complex conductivity of kaolinite, smectite, and clay-sand mixtures was measured in the frequency range 1.4 mHz–12 kHz with various clay contents (100%, 20%, 5%, and 1% in volume of the clay-sand mixture) and salinities (distilled water, [Formula: see text], [Formula: see text], and [Formula: see text] of NaCl in solution). The results indicated the strong impact of the cation exchange capacity of smectite upon the complex conductivity of the material. The quadrature conductivity increased steadily with the clay content and was fairly independent of the pore fluid salinity. A mechanistic induced polarization model was also de...

Localization and characterization of cracks in clay-rocks using frequency and time-domain induced polarization

Geophysical Prospecting, 2012

Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence o... more Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence of cracks in porous rocks and therefore to damage. We performed timedomain and frequency domain IP measurements at the Tournemire Underground Research Laboratory (URL, Aveyron, France) in areas where different types of cracks are observed. These cracks correspond to both tectonic fractures and new cracks associated with stress release and desiccation resulting from the excavation of a gallery. These measurements were performed both in eastern and northern galleries of the test site. The eastern gallery was excavated in 1996 while the northern gallery was excavated recently in 2008. This gives us the opportunity to study the electrical characteristics of the excavation damaged zone surrounding the galleries with respect to the age of the excavation. Longitudinal profiles were performed along the floor of the galleries with 48 Cu/CuSO 4 electrodes separated by a distance of 20 cm. Chargeability and resistivity were inverted using a Gauss-Newton iterative approach assuming an isotropic heterogeneous clay-rock material. The resulting IP tomograms show a correlation between high values of chargeability and the presence of calcite-filled tectonic fractures. X-ray analysis indicates that the presence of pyrite in these fractures is a potential source of the observed IP signals. The cracks associated with the mechanical damage of the formation exhibit low values of chargeability, on the same order of magnitude than the chargeability of the clay-rock matrix and are therefore hardly observable. A smaller IP response associated with the presence of these cracks is observed in the older gallery and this observation is qualitatively related to the desaturation process associated with these cracks. In a specific area of one of the galleries, the presence of calcareous nodules is observed to be an important source of anomalous chargeability. This signature seems to be associated with the presence of pyrite.

Induced polarization of clay-sand mixtures: experiments and modelling

Mesure de la réponse PPS (Polarisation Provoquée Spectrale) de mélanges artificiels argilo-sableux non-consolidés

An experimental investigation was undertaken to measure the Spectral Induced Polarization respons... more

Long-term temporal prediction of terrestrial water storage changes over global basins using GRACE and limited GRACE-FO data

Acta Geodaetica et Geophysica, 2021

Gravity Recovery and Climate Experiment (GRACE) and the GRACE-Follow-On (GRACE-FO) gravimetric mi... more Gravity Recovery and Climate Experiment (GRACE) and the GRACE-Follow-On (GRACE-FO) gravimetric missions provide essential data for remotely measure large-scale Terrestrial Water Storage (TWS) changes on a regional and global scale. However, during the operating time of the gravimetric missions, monthly or almost yearly data gaps may induce and fail to provide continuous information. Quantifying and predicting the TWS variations is very important for uninterrupted environmental monitoring, to be prepared for the consequences of the climatic change and water resources studies. This paper proposes to predict the TWS variability of 19 global basins from 2019 to 2022 using the traditional Seasonal Autoregressive Integrated Moving Average, Error Trend Seasonal, and Singular Spectrum Analysis as newer time series analysis modeling and prediction approach. For this purpose, the integrated GRACE/GRACE-FO Level-3 Release 06 data from the German Research Centre (GFZ) have been privileged. The accuracy of the resulted TWS predictions has been evaluated based on the use of the mentioned approaches, the cross-validation method, and the root-mean-square-error. Using integrated GRACE/GRACE-FO data, the research strategy in this paper is to become a reference to study the TWS prediction of the new GRACE-FO mission and to bridge the gap between GRACE/GRACE-FO missions. For some global basins, the obtained TWS prediction results reveal a continuous negative or positive TWS during the study period 2019–2022. In conclusion, September 2020 and 2021 are expected to be important dates in terms of TWS decrease affecting all basins in different order of magnitude.

Zaman ve Frekans Ortamı Yapay Uçlaşma Yöntemi ile Killi Kayaçlardaki Dokusal ve Su İçeriğiyle ilişkili Heterojenitelerin Belirlenmesi, Uygulama Alanı: Yeraltı araştırma Laboratuarı (Aveyron, Fransa) Characterization of textural and hydric heterogeneities in clay-rocks

by Philippe Cosenza and gonca ahi

Caractérisation des hétérogénéités texturales et hydriques des géomatériaux argileux par la méthode de Polarisation Provoquée : Application à l’EDZ de la station expérimentale de Tournemire

Caractérisation des hétérogénéités texturales et hydriques des Caractérisation des hétérogénéités... more Caractérisation des hétérogénéités texturales et hydriques des Caractérisation des hétérogénéités texturales et hydriques des géomatériaux argileux par la méthode de Polarisation Provoquée : Application à l'EDZ de la station expérimentale de Tournemire. iv RESUME Le travail de recherche présenté dans ce mémoire de thèse s'inscrit dans la problématique générale de la sûreté des stockages de déchets radioactifs en formations argileuses profondes. Le creusement d'ouvrages souterrains dans les argilites induit la création d'une zone endommagée ou perturbée dont la caractérisation constitue un enjeu de sûreté majeur.

A comparison between non-linear optimization methods of Bayesian inversion and genetic algorithm for inverting spectral induced polarization data for Cole-Cole parameters

The induced polarization (IP) method has been used in mining prospecting and increasingly in envi... more The induced polarization (IP) method has been used in mining prospecting and increasingly in environmental investigations because IP measurements are very sensitive to the low frequency capacitive properties of rocks and soils. Cole-Cole model parameters widely use to interpret both of time and frequency domain induced polarization data.

Characterization of heterogeneities in clay-rocks using electrical methods

by Philippe Cosenza and gonca ahi

Geoelectrical Characterization of the Excavation Disturbed Zone (EDZ) in the experimental platform of Tournemire

by Philippe Cosenza and gonca ahi

Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence o... more Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence of cracks in porous rocks and therefore to damage. We performed timedomain and frequency domain IP measurements at the Tournemire Underground Research Laboratory (URL, Aveyron, France) in areas where different types of cracks are observed. These cracks correspond to both tectonic fractures and new cracks associated with stress release and desiccation resulting from the excavation of a gallery. These measurements were performed both in eastern and northern galleries of the test site. The eastern gallery was excavated in 1996 while the northern gallery was excavated recently in 2008. This gives us the opportunity to study the electrical characteristics of the excavation damaged zone surrounding the galleries with respect to the age of the excavation. Longitudinal profiles were performed along the floor of the galleries with 48 Cu/CuSO 4 electrodes separated by a distance of 20 cm. Chargeability and resistivity were inverted using a Gauss-Newton iterative approach assuming an isotropic heterogeneous clay-rock material. The resulting IP tomograms show a correlation between high values of chargeability and the presence of calcite-filled tectonic fractures. X-ray analysis indicates that the presence of pyrite in these fractures is a potential source of the observed IP signals. The cracks associated with the mechanical damage of the formation exhibit low values of chargeability, on the same order of magnitude than the chargeability of the clay-rock matrix and are therefore hardly observable. A smaller IP response associated with the presence of these cracks is observed in the older gallery and this observation is qualitatively related to the desaturation process associated with these cracks. In a specific area of one of the galleries, the presence of calcareous nodules is observed to be an important source of anomalous chargeability. This signature seems to be associated with the presence of pyrite.

Characterization of heterogeneities in clay-rocks using electrical methods

Geoelectrical Characterization of the Excavation Disturbed Zone (EDZ) in the experimental platform of Tournemire

Zaman ve Spektral IP Yöntemi ile Killi Kayaçlardaki Dokusal ve Su İçeriğiyle İlişkili Heterojenitelerin Belirlenmesi

Structural characterization of the disturbed zone in the argillaceous Tournemire platform with timedomain induced polarization method

Effective medium approaches to model spectral IP responses in soils: Impact of microstructure, EEGS NSGS Workshop on Induced Polarization: Research and Recent Advances in Near Surface Applications

JNGG 2010 pp 867-874 Okay

Modelling the induced polarization of bentonite-sand mixtures

Modelling the induced polarization of bentonite-sand mixtures. 3rd International Workshop on Indu... more Modelling the induced polarization of bentonite-sand mixtures. 3rd International Workshop on Induced Polarization, Apr 2014, Ile d'Oléron, France. 2 p. HAL Id: hal-00959864 https://hal-brgm.archives-ouvertes.fr/hal-00959864 Submitted on 17 Mar 2014 HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci-entific research documents, whether they are pub-lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt e a la diffusion de documents scientifiques de niveau recherche, publiés ou non emanant de etablissements d'enseignement et de recherche français oú etrangers, des laboratoires publics ou privés.

Experimental investigation of the SIP response of saturated clay-sand mixtures: impact of the clay mineralogy

Caractérisation géoélectrique de la zone endommagée des galeries sur le site de Tournemire

Characterization of Excavation Damaged Zone and its structural heterogeneities with Time and Spectral IP methods

International Geophysical Conference and Oil & Gas Exhibition, Istanbul, Turkey, 17-19 September 2012, 2012

Thestreamlined synthesis of compounds with wide spectrum of essential properties is prospective l... more Thestreamlined synthesis of compounds with wide spectrum of essential properties is prospective lines of development of chemistry of nitrogen containing heterocyclic compounds. Triazines hold a specific place among the great variety of nitrogen containing heterocyclic compounds. Derivatives of unsymmetrical triazines demonstrate a large range of bioactive action, they were offered in the quality of herbicides, plant growth regulators, insecticides, antifungal, acaricide, pharmaceutical and veterinary preparations, stabilizer-antioxygen of polymers and also as corrosion inhibitor. Compounds of 1,2,4-triazinones series are widely reported in the publications, but unsymmetrical triazines particularly their acyl and amino derivatives haven't been studied detailed. Especially there are not many articles about route for the synthesis of acyl and amino

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

GEOPHYSICS, 2014

Spectral induced polarization or complex conductivity is a promising electric method in hydrogeop... more Spectral induced polarization or complex conductivity is a promising electric method in hydrogeophysics because of its sensitivity to water saturation, permeability, and particle size distribution (PSD). However, the physical and chemical mechanisms that generate the low-frequency complex conductivity of clays are still debated. To explain these mechanisms, the complex conductivity of kaolinite, smectite, and clay-sand mixtures was measured in the frequency range 1.4 mHz–12 kHz with various clay contents (100%, 20%, 5%, and 1% in volume of the clay-sand mixture) and salinities (distilled water, [Formula: see text], [Formula: see text], and [Formula: see text] of NaCl in solution). The results indicated the strong impact of the cation exchange capacity of smectite upon the complex conductivity of the material. The quadrature conductivity increased steadily with the clay content and was fairly independent of the pore fluid salinity. A mechanistic induced polarization model was also de...

Localization and characterization of cracks in clay-rocks using frequency and time-domain induced polarization

Geophysical Prospecting, 2012

Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence o... more Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence of cracks in porous rocks and therefore to damage. We performed timedomain and frequency domain IP measurements at the Tournemire Underground Research Laboratory (URL, Aveyron, France) in areas where different types of cracks are observed. These cracks correspond to both tectonic fractures and new cracks associated with stress release and desiccation resulting from the excavation of a gallery. These measurements were performed both in eastern and northern galleries of the test site. The eastern gallery was excavated in 1996 while the northern gallery was excavated recently in 2008. This gives us the opportunity to study the electrical characteristics of the excavation damaged zone surrounding the galleries with respect to the age of the excavation. Longitudinal profiles were performed along the floor of the galleries with 48 Cu/CuSO 4 electrodes separated by a distance of 20 cm. Chargeability and resistivity were inverted using a Gauss-Newton iterative approach assuming an isotropic heterogeneous clay-rock material. The resulting IP tomograms show a correlation between high values of chargeability and the presence of calcite-filled tectonic fractures. X-ray analysis indicates that the presence of pyrite in these fractures is a potential source of the observed IP signals. The cracks associated with the mechanical damage of the formation exhibit low values of chargeability, on the same order of magnitude than the chargeability of the clay-rock matrix and are therefore hardly observable. A smaller IP response associated with the presence of these cracks is observed in the older gallery and this observation is qualitatively related to the desaturation process associated with these cracks. In a specific area of one of the galleries, the presence of calcareous nodules is observed to be an important source of anomalous chargeability. This signature seems to be associated with the presence of pyrite.

Induced polarization of clay-sand mixtures: experiments and modelling

Mesure de la réponse PPS (Polarisation Provoquée Spectrale) de mélanges artificiels argilo-sableux non-consolidés

An experimental investigation was undertaken to measure the Spectral Induced Polarization respons... more

Long-term temporal prediction of terrestrial water storage changes over global basins using GRACE and limited GRACE-FO data

Acta Geodaetica et Geophysica, 2021

Gravity Recovery and Climate Experiment (GRACE) and the GRACE-Follow-On (GRACE-FO) gravimetric mi... more Gravity Recovery and Climate Experiment (GRACE) and the GRACE-Follow-On (GRACE-FO) gravimetric missions provide essential data for remotely measure large-scale Terrestrial Water Storage (TWS) changes on a regional and global scale. However, during the operating time of the gravimetric missions, monthly or almost yearly data gaps may induce and fail to provide continuous information. Quantifying and predicting the TWS variations is very important for uninterrupted environmental monitoring, to be prepared for the consequences of the climatic change and water resources studies. This paper proposes to predict the TWS variability of 19 global basins from 2019 to 2022 using the traditional Seasonal Autoregressive Integrated Moving Average, Error Trend Seasonal, and Singular Spectrum Analysis as newer time series analysis modeling and prediction approach. For this purpose, the integrated GRACE/GRACE-FO Level-3 Release 06 data from the German Research Centre (GFZ) have been privileged. The accuracy of the resulted TWS predictions has been evaluated based on the use of the mentioned approaches, the cross-validation method, and the root-mean-square-error. Using integrated GRACE/GRACE-FO data, the research strategy in this paper is to become a reference to study the TWS prediction of the new GRACE-FO mission and to bridge the gap between GRACE/GRACE-FO missions. For some global basins, the obtained TWS prediction results reveal a continuous negative or positive TWS during the study period 2019–2022. In conclusion, September 2020 and 2021 are expected to be important dates in terms of TWS decrease affecting all basins in different order of magnitude.

Zaman ve Frekans Ortamı Yapay Uçlaşma Yöntemi ile Killi Kayaçlardaki Dokusal ve Su İçeriğiyle ilişkili Heterojenitelerin Belirlenmesi, Uygulama Alanı: Yeraltı araştırma Laboratuarı (Aveyron, Fransa) Characterization of textural and hydric heterogeneities in clay-rocks

by Philippe Cosenza and gonca ahi

Caractérisation des hétérogénéités texturales et hydriques des géomatériaux argileux par la méthode de Polarisation Provoquée : Application à l’EDZ de la station expérimentale de Tournemire

Caractérisation des hétérogénéités texturales et hydriques des Caractérisation des hétérogénéités... more Caractérisation des hétérogénéités texturales et hydriques des Caractérisation des hétérogénéités texturales et hydriques des géomatériaux argileux par la méthode de Polarisation Provoquée : Application à l'EDZ de la station expérimentale de Tournemire. iv RESUME Le travail de recherche présenté dans ce mémoire de thèse s'inscrit dans la problématique générale de la sûreté des stockages de déchets radioactifs en formations argileuses profondes. Le creusement d'ouvrages souterrains dans les argilites induit la création d'une zone endommagée ou perturbée dont la caractérisation constitue un enjeu de sûreté majeur.

A comparison between non-linear optimization methods of Bayesian inversion and genetic algorithm for inverting spectral induced polarization data for Cole-Cole parameters

The induced polarization (IP) method has been used in mining prospecting and increasingly in envi... more The induced polarization (IP) method has been used in mining prospecting and increasingly in environmental investigations because IP measurements are very sensitive to the low frequency capacitive properties of rocks and soils. Cole-Cole model parameters widely use to interpret both of time and frequency domain induced polarization data.

Characterization of heterogeneities in clay-rocks using electrical methods

by Philippe Cosenza and gonca ahi

Geoelectrical Characterization of the Excavation Disturbed Zone (EDZ) in the experimental platform of Tournemire

by Philippe Cosenza and gonca ahi

Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence o... more Induced polarization (IP) is a geophysical method that is potentially sensitive to the presence of cracks in porous rocks and therefore to damage. We performed timedomain and frequency domain IP measurements at the Tournemire Underground Research Laboratory (URL, Aveyron, France) in areas where different types of cracks are observed. These cracks correspond to both tectonic fractures and new cracks associated with stress release and desiccation resulting from the excavation of a gallery. These measurements were performed both in eastern and northern galleries of the test site. The eastern gallery was excavated in 1996 while the northern gallery was excavated recently in 2008. This gives us the opportunity to study the electrical characteristics of the excavation damaged zone surrounding the galleries with respect to the age of the excavation. Longitudinal profiles were performed along the floor of the galleries with 48 Cu/CuSO 4 electrodes separated by a distance of 20 cm. Chargeability and resistivity were inverted using a Gauss-Newton iterative approach assuming an isotropic heterogeneous clay-rock material. The resulting IP tomograms show a correlation between high values of chargeability and the presence of calcite-filled tectonic fractures. X-ray analysis indicates that the presence of pyrite in these fractures is a potential source of the observed IP signals. The cracks associated with the mechanical damage of the formation exhibit low values of chargeability, on the same order of magnitude than the chargeability of the clay-rock matrix and are therefore hardly observable. A smaller IP response associated with the presence of these cracks is observed in the older gallery and this observation is qualitatively related to the desaturation process associated with these cracks. In a specific area of one of the galleries, the presence of calcareous nodules is observed to be an important source of anomalous chargeability. This signature seems to be associated with the presence of pyrite.