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Nilfouroushan, Faramarz, Senior LecturerORCID iD iconorcid.org/0000-0003-1744-7004
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Publications (10 of 51) Show all publications
Nilfouroushan, F. & Fryksten, J. (2020). Analysis of Clay-Induced Land Subsidence in Uppsala City Using Sentinel-1 SAR Data and Precise Leveling. In: : . Paper presented at EGU General Assembly 2020, 3-5 May, Vienna, Austria. , 7322
Open this publication in new window or tab >>Analysis of Clay-Induced Land Subsidence in Uppsala City Using Sentinel-1 SAR Data and Precise Leveling
2020 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Land subsidence and its subsequent hazardous effects on buildings and urban infrastructure areimportant issues in many cities around the world. The city of Uppsala in Sweden is undergoing significant subsidence in areas that are located on clay. Underlying clay units in parts of Uppsalaact as mechanically weak layers, which for instance, cause sinking of the ground surface and tilting buildings. In this study, a Persistent Scatterer InSAR (PSI) analysis was performed to map theongoing ground deformation in Uppsala. The subsidence rate measured with PSI was validatedwith precise leveling data at different locations. Two ascending and descending data sets wereanalyzed using SARPROZ software, with Sentinel-1 data from the period March 2015 to April 2019.After the PSI analyses, comparative permanent scatterer (PS) points and metal pegs (measuredwith precise leveling) were identified creating validation pairs. According to the PSI analyses,Uppsala was undergoing significant subsidence in some areas, with an annual rate of about 6mm/year in the line-of-sight direction. Interestingly, the areas of great deformation wereexclusively found on postglacial clay.

Keywords
Uppsala, Deformation, Subsidence, InSAR, PSI, Clay, Geology
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31556 (URN)
Conference
EGU General Assembly 2020, 3-5 May, Vienna, Austria
Note

kommande

Available from: 2020-01-25 Created: 2020-01-25 Last updated: 2020-01-27Bibliographically approved
Darvishi, M., Cuozzo, G., Bruzzone, L. & Nilfouroushan, F. (2020). Performance evaluation of phase and weather-based models in atmospheric correction with Sentinel-1data: Corvara landslide in the Alps. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Open this publication in new window or tab >>Performance evaluation of phase and weather-based models in atmospheric correction with Sentinel-1data: Corvara landslide in the Alps
2020 (English)In: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, ISSN 1939-1404, E-ISSN 2151-1535Article in journal (Refereed) Epub ahead of print
Abstract [en]

Phase delay caused by atmospheric effects due to spatial and temporal variations of pressure, temperature, and water vapor content is one of the major errors ources in estimation of ground deformation by interferometric synthetic aperture radar (InSAR). Therefore, accuracy of ground deformation measurement is highly contingent on the robustness of the atmospheric correction techniques. These techniques rely eitheron auxiliary data such as numerical weather models or on the analysis of the interferometric phase itself. The accuracyin phase delays estimation of mixing effectsof turbulent delay in atmosphere and stratified delay in lower troposphere is a key factor in determination of performanceof each technique. Hence, the performance evaluation of the techniques is required in order toassess their potentials, robustness and limitations. This paper analyzes and evaluates the performance of four numerical weather models (i.e., ERA-Interim, ERA5, MERRA2 and WRF) and two phase-based techniques (i.e., linear and power law) to estimate phase delay using Sentinel-1A/B data over the Corvara landslide located in the Alps. The GPS data and GACOS product were used to validate the results. We generally found that ERA5 outperformed among other weather models with a phase standard deviation reduction of 77.7%(with respect to the InSAR phase), a correlation coefficient of 0.86 (between InSAR phase and estimated tropospheric delay) and a less significant error in the velocity estimation of the landslide.

Keywords
Phase and weather-based models, atmospheric correction, GPS, InSAR, Sentinel-1, phase delay
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-32060 (URN)10.1109/JSTARS.2020.2969726 (DOI)
Available from: 2020-03-21 Created: 2020-03-21 Last updated: 2020-03-26Bibliographically approved
Gido, N. A. A., Amin, H., Bagherbandi, M. & Nilfouroushan, F. (2020). Satellite monitoring of mass changes and ground subsidence in Sudan’s oil fields using GRACE and Sentinel-1 data. In: : . Paper presented at EGU General Assembly 2020, Vienna, Australia, 3-8 May.
Open this publication in new window or tab >>Satellite monitoring of mass changes and ground subsidence in Sudan’s oil fields using GRACE and Sentinel-1 data
2020 (English)Conference paper, Oral presentation with published abstract (Other (popular science, discussion, etc.))
Abstract [en]

Monitoring environmental hazards, due to natural and anthropogenic causes, is one of the important issues, which requires proper data, models, and cross-validation of the results. The geodetic satellite missions, e.g. the Gravity Recovery and Climate Experiment (GRACE) and Sentinel-1, are very useful in this aspect. GRACE missions are dedicated to model the temporal variations of the Earth’s gravity field and mass transportation in the Earth’s surface, whereas Sentinel-1 collects Synthetic Aperture Radar (SAR) data which enables us to measure the ground movements accurately. Extraction of large volumes of water and oil decreases the reservoir pressure, form compaction and consequently land subsidence occurs which can be analyzed by both GRACE and Sentinel-1 data. In this paper, large-scale groundwater storage (GWS) changes are studied using the GRACE monthly gravity field models together with different hydrological models over the major oil reservoirs in Sudan, i.e. Heglig, Bamboo, Neem, Diffra and Unity-area oil fields. Then we correlate the results with the available oil wells production data for the period of 2003-2012. In addition, using the only freely available Sentinel-1 data, collected between November 2015 and April 2019, the ground surface deformation associated with this oil and water depletion is studied. Due to the lack of terrestrial geodetic monitoring data in Sudan, the use of GRACE and Sentinel-1 satellite data is very valuable to monitor water and oil storage changes and their associated land subsidence over our region of interest. Our results show that there is a significant correlation between the GRACE-based GWS change and extracted oil and water volumes. The trend of GWS changes due to water and oil depletion ranged from -18.5 to -6.2mm/year using the CSR GRACE monthly solutions and the best tested hydrological model in this study. Moreover, our Sentinel-1 SAR data analysis using Persistent Scatterer Interferometry (PSI) method shows high rate of subsidence i.e. -24.5, -23.8, -14.2 and -6 mm/year over Heglig, Neem, Diffra and Unity-area oil fields respectively. The results of this study can help us to control the integrity and safety of operations and infrastructure in that region, as well as to study the groundwater/oil storage behavior.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31486 (URN)
Conference
EGU General Assembly 2020, Vienna, Australia, 3-8 May
Available from: 2020-01-18 Created: 2020-01-18 Last updated: 2020-01-20Bibliographically approved
Gido, N. A. A., Amin, H., Bagherbandi, M. & Nilfouroushan, F. (2020). Satellite monitoring of mass changes and ground subsidence in Sudan’s oil fields using GRACE and Sentinel-1 data. In: : . Paper presented at EGU General Assembly 2020, Vienna, Austria, 3-8 May.
Open this publication in new window or tab >>Satellite monitoring of mass changes and ground subsidence in Sudan’s oil fields using GRACE and Sentinel-1 data
2020 (English)Conference paper, Oral presentation with published abstract (Other (popular science, discussion, etc.))
Abstract [en]

Monitoring environmental hazards, due to natural and anthropogenic causes, is one of the important issues, which requires proper data, models, and cross-validation of the results. The geodetic satellite missions, e.g. the Gravity Recovery and Climate Experiment (GRACE) and Sentinel-1, are very useful in this aspect. GRACE missions are dedicated to model the temporal variations of the Earth’s gravity field and mass transportation in the Earth’s surface, whereas Sentinel-1 collects Synthetic Aperture Radar (SAR) data which enables us to measure the ground movements accurately. Extraction of large volumes of water and oil decreases the reservoir pressure, form compaction and consequently land subsidence occurs which can be analyzed by both GRACE and Sentinel-1 data. In this paper, large-scale groundwater storage (GWS) changes are studied using the GRACE monthly gravity field models together with different hydrological models over the major oil reservoirs in Sudan, i.e. Heglig, Bamboo, Neem, Diffra and Unity-area oil fields. Then we correlate the results with the available oil wells production data for the period of 2003-2012. In addition, using the only freely available Sentinel-1 data, collected between November 2015 and April 2019, the ground surface deformation associated with this oil and water depletion is studied. Due to the lack of terrestrial geodetic monitoring data in Sudan, the use of GRACE and Sentinel-1 satellite data is very valuable to monitor water and oil storage changes and their associated land subsidence over our region of interest. Our results show that there is a significant correlation between the GRACE-based GWS change and extracted oil and water volumes. The trend of GWS changes due to water and oil depletion ranged from -18.5 to -6.2mm/year using the CSR GRACE monthly solutions and the best tested hydrological model in this study. Moreover, our Sentinel-1 SAR data analysis using Persistent Scatterer Interferometry (PSI) method shows high rate of subsidence i.e. -24.5, -23.8, -14.2 and -6 mm/year over Heglig, Neem, Diffra and Unity-area oil fields respectively. The results of this study can help us to control the integrity and safety of operations and infrastructure in that region, as well as to study the groundwater/oil storage behavior.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31902 (URN)
Conference
EGU General Assembly 2020, Vienna, Austria, 3-8 May
Available from: 2020-02-18 Created: 2020-02-18 Last updated: 2020-02-18Bibliographically approved
Kaviani, A., Mahmoodabadi, M., Rümpker, G., Yamini-Fard, F., Tatar, M., Moradi, A. & Nilfouroushan, F. (2020). SKS splitting observations across the Iranian plateau and Zagros: the role of lithosphere deformation and mantle flow. In: : . Paper presented at EGU General Assembly 2020, 3-8 May, Vienna, Austria.
Open this publication in new window or tab >>SKS splitting observations across the Iranian plateau and Zagros: the role of lithosphere deformation and mantle flow
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2020 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

We used more than one decade of core-refracted teleseismic shear (SKS) waveforms recorded atmore than 160 broadband seismic stations across the Iranian plateau and Zagros to investigateseismic anisotropy beneath the region. Splitting analysis of SKS waveforms provides two mainparameters, i.e., fast polarization direction and split delay time, which serve as proxies for thetrend and strength of seismic anisotropy beneath the stations. Our observation revealed acomplex pattern of splitting parameters with variations in the trend and strength of anisotropyacross the tectonic boundaries. We also verified the presence of multiple layers of anisotropy inconjunction with the lithosphere deformation and mantle flow field. Our observation andmodeling imply that a combined system of lithosphere deformation and asthenospheric flow islikely responsible for the observed pattern of anisotropy across the Iranian Plateau and Zagros.The rotational pattern of the fast polarization directions observed locally in Central Zagros mayindicate the diversion of mantle flow around a continental keel beneath the Zagros. Thecorrelation between the variation in lithosphere thickness and the trend of anisotropy in the studyarea implies that the topography of the base of lithosphere is also a determining factor for thepattern of mantle flow inferred from the observations.

Keywords
Deformation, Iran, Mantel flow, Geodynamics, Zagroas
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31557 (URN)
Conference
EGU General Assembly 2020, 3-8 May, Vienna, Austria
Note

kommande

Available from: 2020-01-25 Created: 2020-01-25 Last updated: 2020-01-27Bibliographically approved
Khorrami, F., Vernant, P., Masson, F., Nilfouroushan, F., Mousavi, Z., Nankali, H., . . . Alijanzade, M. (2019). An up-to-date block model and strain rate map of Iran using integrated campaign-mode and permanent GPS velocities. In: 27th IUGG General Assembly: G06 - Posters - Monitoring and Understanding the Dynamic Earth With Geodetic Observations. Paper presented at 27th IUGG General Assembly, 8-18 July, 2019, Montreal, Canada.
Open this publication in new window or tab >>An up-to-date block model and strain rate map of Iran using integrated campaign-mode and permanent GPS velocities
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2019 (English)In: 27th IUGG General Assembly: G06 - Posters - Monitoring and Understanding the Dynamic Earth With Geodetic Observations, 2019Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Iran accommodates a large part of the ongoing Arabia-Eurasia collision deformation. Because of such active tectonics, the country suffers from intensive seismicity and frequent destructive earthquakes in different locations.To study further the crustal deformation in Iran, we processed the data collected during 10 years (2006-2015) from the Iranian Permanent GNSS Network and combined them with previously published velocity solutions from GPS survey measurements during 1997–2013. We analysed this velocity field using a continuum approach to compute a new strain rate map for this region and we designed a block model based on the main geological, morphological, and seismic structures. Comparison between both approaches suggests similar results and allow us to present the first comprehensive first order fault slip rate estimates for the whole of Iran. Our results confirm most of the results from previous geodetic studies. Moreover, we also show a trade-off between the coupling ratio of the Iranian Makran subduction interface and the kinematic of the faults north of the Makran in the Jazmurian depression. Although too scarce to accurately estimate a coupling ratio, we show that coupling higher than 0.4 on the plate interface down to a depth of 25 km will induce extension on the E-W faults in the Jazmurian region. However, the sites close to the shoreline suggest a low coupling ratio, hence the coupling on this plate interface is probably more complicated than previously described and the Iranian Makran subduction interface mechanical behaviour might be similar to that on the Hellenic subduction zone.

Keywords
GPS, deformation, Iran, strain, geodynamics
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29657 (URN)
Conference
27th IUGG General Assembly, 8-18 July, 2019, Montreal, Canada
Available from: 2019-06-04 Created: 2019-06-04 Last updated: 2019-08-08Bibliographically approved
Khorrami, F., Vernant, P., Masson, F., Nilfouroushan, F., Mousavi, Z., Nankali, H., . . . Alijanzade, M. (2019). An up-to-date crustal deformation map of Iran using integrated campaign-mode and permanent GPS velocities. Geophysical Journal International, 217(2), 832-843
Open this publication in new window or tab >>An up-to-date crustal deformation map of Iran using integrated campaign-mode and permanent GPS velocities
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2019 (English)In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 217, no 2, p. 832-843Article in journal (Refereed) Published
Abstract [en]

We present the most extensive and up-to-date unified GPS velocity field for Iran. We processed the data collected during 10 years (2006–2015) from the Iranian Permanent GNSS Network (IPGN) and combined them with previously published velocity solutions from GPS survey measurements during 1997–2013. We analysed this velocity field using a continuum approach to compute a new strain rate map for this region and we designed a block model based on the main geological, morphological, and seismic structures. Comparison between both approaches suggests similar results and allow us to present the first comprehensive first order fault slip rate estimates for the whole of Iran. Our results confirm most of the results from previous geodetic studies. But we also show a trade-off between the coupling ratio of the Iranian Makran subduction interface and the kinematic of the faults north of the Makran in the Jazmurian depression. Indeed, although too scarce to accurately estimate a coupling ratio, we show that coupling higher than 0.4 on the plate interface down to a depth of 25 km will induce extension on the E-W faults in the Jazmurian region. However, the sites close to the shoreline suggest a low coupling ratio, hence the coupling on this plate interface is probably more complicated than previously described and the Iranian Makran subduction interface mechanical behaviour might be similar to that on the Hellenic subduction zone.

Place, publisher, year, edition, pages
Oxford University Press, 2019
Keywords
GPS, Iran, Strain, deformation, Zagros, Makran
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29221 (URN)10.1093/gji/ggz045 (DOI)000465608000007 ()2-s2.0-85063728224 (Scopus ID)
Available from: 2019-02-02 Created: 2019-02-02 Last updated: 2019-11-25Bibliographically approved
Fryksten, J. & Nilfouroushan, F. (2019). Analysis of Clay-Induced Land Subsidence in Uppsala City Using Sentinel-1 SAR Data and Precise Leveling. Remote Sensing, 11(23), Article ID 2764.
Open this publication in new window or tab >>Analysis of Clay-Induced Land Subsidence in Uppsala City Using Sentinel-1 SAR Data and Precise Leveling
2019 (English)In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 11, no 23, article id 2764Article in journal (Refereed) Published
Abstract [en]

Land subsidence and its subsequent hazardous effects on buildings and urban infrastructure are important issues in many cities around the world. The city of Uppsala in Sweden is undergoing significant subsidence in areas that are located on clay. Underlying clay units in parts of Uppsala act as mechanically weak layers, which for instance, cause sinking of the ground surface and tilting buildings. Interferometric Synthetic Aperture Radar (InSAR) has given rise to new methods of measuring movements on earth surface with a precision of a few mm. In this study, a Persistent Scatterer InSAR (PSI) analysis was performed to map the ongoing ground deformation in Uppsala. The subsidence rate measured with PSI was validated with precise leveling data at different locations. Two ascending and descending data sets were analyzed using SARPROZ software, with Sentinel-1 data from the period March 2015 to April 2019. After the PSI analyses, comparative permanent scatterer (PS) points and metal pegs (measured with precise leveling) were identified creating validation pairs. According to the PSI analyses, Uppsala was undergoing significant subsidence in some areas, with an annual rate of about 6 mm/year in the line-of-sight direction. Interestingly, the areas of great deformation were exclusively found on postglacial clay.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Sentinel-1; PSI; InSAR; precise leveling; deformation; clay
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-31052 (URN)10.3390/rs11232764 (DOI)000508382100045 ()2-s2.0-85076549663 (Scopus ID)
Available from: 2019-11-23 Created: 2019-11-23 Last updated: 2020-02-07Bibliographically approved
Kaviani, A., Mahmoodabadi, M., Rümpker, G., Yamini-Fard, F., Tatar, M., Motavalli-Anbaran, J., . . . Nilfouroushan, F. (2019). Complex pattern of seismic anisotropy beneath the Iranian plateau and Zagros. In: : . Paper presented at European Geosciences Union (General Assembly), 7-12 April 209, Vienna, Austria. , 21, Article ID EGU2019-13815-1.
Open this publication in new window or tab >>Complex pattern of seismic anisotropy beneath the Iranian plateau and Zagros
Show others...
2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

We performed shear wave splitting analyses on core-refracted teleseismic shear waveforms from 150 broad-bandstations across the Iranian plateau and Zagros to investigate seismic anisotropy in the region. Seismic anisotropyis quantified by shear-wave splitting parameters, i.e. fast polarization direction and split delay time.Our measurements revealed a complex pattern of splitting parameters with variations in the trend and strength ofanisotropy across the tectonic boundaries. This complex pattern implies that a system of simple asthenosphericflow related to the absolute plate motion cannot alone explain our observations and that the lithosphere also hasa significant contribution in many parts. We compare our results to the surface deformation and velocity fieldsinferred from geodetic measurements to assess the role of the mantle in continental deformation. The rotationalpattern of the fast directions around the collision zone in Central Zagros may indicate the presence of a mantleflow around a continental keel beneath the Zagros. The agreement between the crustal and mantle deformationfield in Central Iran implies a vertically coherent deformation in this region, whereas the azimuthal variations insplitting parameters in the collision zone may suggest multi-layered anisotropy with different contributions fromthe crust and mantle.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29183 (URN)
Conference
European Geosciences Union (General Assembly), 7-12 April 209, Vienna, Austria
Available from: 2019-01-27 Created: 2019-01-27 Last updated: 2019-11-29Bibliographically approved
Nilfouroushan, F., Jivall, L., Al Munaizel, N., Lilje, C. & Kempe, C. (2019). Maintenance of the National Realisation of ETRS89 in Sweden: re-analysis of 20-years GPS data for SWEREF stations. In: : . Paper presented at European Geosciences Union (General Assembly), 7-12 April 2019, Vienna, Austria. , 21, Article ID EGU2019-7211-3.
Open this publication in new window or tab >>Maintenance of the National Realisation of ETRS89 in Sweden: re-analysis of 20-years GPS data for SWEREF stations
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2019 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The national geodetic reference frame of Sweden called SWEREF 99, was adopted in 2000 by EUREF as therealization of ETRS89 in Sweden and was officially introduced in 2001 as a national reference frame, thateventually in 2007 replaced the former reference frame. The SWEREF 99 reference frame is defined by an activeapproach through the 21 fundamental SWEPOS permanent GNSS stations, hence relying on positioning servicessuch as the network real time kinematic (NRTK) and post processing service. The SWEREF 99 coordinates areassumed to be fixed in time and no temporal variations are expected. However, the stability of the stations andtheir coordinates can be altered due to equipment change or software as well as local movements at the referencestations.To be able to check all alterations mentioned above and having a backup national network of GNSS stations,approximately 300 passive so-called consolidation stations are used. The consolidation stations are a subset (mainpart) of the so-called SWEREF stations established from 1996 and onwards. All 300 stations are remeasured withstatic GNSS for 2x24 hours using choke ring antennas on a yearly basis with 50 stations each year. The originalprocessing was done with the Bernese GNSS software (here called Bernese original) and the reprocessing wascarried out with both the Bernese and the GAMIT-GLOBK software packages during 2017-2018.The resulting coordinates in SWEREF 99 from GAMIT and Bernese processing are equal at 1.2 mm level forhorizontal and 4 mm for vertical components (1 sigma) when using the same models and processing strategy.The original processing, which partly is based on other models and parameters, differs slightly more (rms 2.4mm) for the north component. Our analysis both from Bernese and GAMIT shows that the standard uncertaintiesfor a single SWEREF 99 determination (2x24 hrs) is 2 mm for the horizontal components and 6-7 mm inheight. However, since some stations are slowly moving they have slightly increased the estimated uncertainties.It is interesting to note that the repeatability is on the same level also for the original processing, where wehave differences in models and parameters used during the years. This indicates that the SWEREF-concept ofdetermining SWEREF99 coordinates has worked well on the mentioned uncertainty level.We performed trend analysis and statistical tests to investigate the stability of the estimated SWEREF 99coordinates. The analysed station time series (minimum three observations) showed that about 14% of the stationshad significant trends at the 95%-level. The possible explanation for those trends can be either local deformationand/or residuals of uplift model and/or computational effects such as lack of good or enough close-by stations forHelmert transformations from ITRF to SWEREF 99.The outcomes of the new processing and analysis reported here, are used to analyse the stability of SWEREF99 after two decades. The results have also been used to define the SWEREF 99 component in the fit of theSWEN17_RH2000 new geoid model to SWEREF 99 and RH 2000 (Swedish realization of EVRS).

Keywords
GNSS, SWEREF, Reference frames, SWEDEN
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29182 (URN)
Conference
European Geosciences Union (General Assembly), 7-12 April 2019, Vienna, Austria
Available from: 2019-01-27 Created: 2019-01-27 Last updated: 2019-11-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1744-7004

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