1,254 research outputs found

    Анализ процесса добычи нефти и газа винтовыми насосами на месторождениях России.

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    Объектом исследования является нефтяные и угольные месторождения, скважины которых оборудованы установками винтовых насосов. Цель работы – повышение эффективности работы установок электровинтового насоса и формулирования научно-методических основ их применения в различных геолого-физических условиях. В процессе исследования: изучались основные причины отказа установок винтового насоса, проведен углубленный анализ технических и технологических характеристик работы установок, а также основные причины, осложняющие работу винтовых насосов и подбор оптимальных условий эксплуатации при осложненных условиях эксплуатации.The object of the study is oil and coal deposits, the wells of which are equipped with screw pumps. The aim of the work is to increase the efficiency of the electric screw pump installations and formulate the scientific and methodological bases for their application in various geological and physical conditions. In the process of research: the main reasons for the failure of screw pump installations were studied, in-depth analysis of technical and technological characteristics of plant operation, as well as the main reasons complicating the operation of screw pumps and selection of optimal operating conditions under complicated operating conditions

    Intra-annual dynamics of ice-rich riverbank erosion in the central Lena Delta

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    Arctic warming accelerates the rapid degradation of ice- and organic-rich permafrost landscapes through thermokarst and thermal-erosion. These processes lead to the retreat of ice-rich coasts, riverbanks, lake shorelines, to surface subsidence and gullying. The subsequent reactivation of ancient carbon previously stored in the eroded ice- and organic-rich sediments could have tremendous impact on the carbon cycle from regional to global scale. Yet, information at high temporal and spatial resolution is often lacking to describe the rates and the timing of permafrost degradation. Synthetic aperture radar (SAR), which operates independently of atmospheric distortions, is particularly valuable to alleviate these issues because of its potential for high temporal resolution monitoring in a region where cloud cover often limits the use of optical satellite imagery. In this study, we used SAR data to investigate the spatiotemporal dynamic of a rapidly degrading ice- and organic-rich up to 50-m-high and 2000-m long riverbank in the central Lena Delta. Our main objectives were to 1) assess the applicability of synthetic aperture radar (SAR) satellite data for high-temporal resolution monitoring of rapidly eroding riverbanks and 2) to identify the seasonal timing of ice-rich permafrost riverbank erosion. We analyzed a unique time-series of high-spatial and temporal SAR images from the German TerraSAR-X (TSX) satellite, operating in X-band wavelength, as well as very high resolution optical satellite imagery and in-situ time-lapse data. We processed 77 HH- polarized SAR backscatter images with acquisition dates between August 2012 and October 2015. The imagery was first pre-processed using the Sentinel-1 toolbox from the European Space Agency. We then applied a thresholding to better identify the transition line from undisturbed tundra surface to the actively eroding cliff we refer to as cliff top line. We then calculated cliff top retreat rates and finally compared these with environmental baseline data to identify the main driving factors of riverbank retreat. Visual interpretation of the TSX time-series showed that the cliff of the riverbank is only visible in the months June to October. Annual erosion rates were in the same range when comparing the optical reference with the SAR datasets. The in-situ time-lapse data for the summer of 2015 showed similar results for the intra-annual erosion compared to the SAR derived results. Based on the SAR dataset we detected mostly constant erosion rates at our test site throughout the thawing period for the years 2013, 2014 and 2015. Our results show that the cliff-top at the test site retreats constantly over the thawing season rather than event driven (i.e. through the spring peak discharge only). The studied cliff top is protected from spring flood events by sandbanks in front of the riverbank. However, runoff caused by permafrost thaw, precipitation and flooding will degrade the protecting sand banks and consequently will lead to a reconnection of the cliff system to the Lena River System, even when water level is lower towards the end of the thawing season. We conclude that x-band backscatter time-series are valuable for monitoring rapid permafrost degradation with high spatial and temporal resolution. Our results indicate that cliff top erosion of ice-rich riverbanks takes place constantly over the thawing period and is not event driven

    Size Distributions of Arctic Waterbodies Reveal Consistent Relations in Their Statistical Moments in Space and Time

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    Arctic lowlands are characterized by large numbers of small waterbodies, which are known to affect surface energy budgets and the global carbon cycle. Statistical analysis of their size distributions has been hindered by the shortage of observations at sufficiently high spatial resolutions. This situation has now changed with the high-resolution (<5 m) circum-Arctic Permafrost Region Pond and Lake (PeRL) database recently becoming available. We have used this database to make the first consistent, high-resolution estimation of Arctic waterbody size distributions, with surface areas ranging from 0.0001 km2 (100 m2) to 1 km2. We found that the size distributions varied greatly across the thirty study regions investigated and that there was no single universal size distribution function (including power-law distribution functions) appropriate across all of the study regions. We did, however, find close relationships between the statistical moments (mean, variance, and skewness) of the waterbody size distributions from different study regions. Specifically, we found that the spatial variance increased linearly with mean waterbody size (R2 = 0.97, p < 2.2e-16) and that the skewness decreased approximately hyperbolically. We have demonstrated that these relationships (1) hold across the 30 Arctic study regions covering a variety of (bio)climatic and permafrost zones, (2) hold over time in two of these study regions for which multi-decadal satellite imagery is available, and (3) can be reproduced by simulating rising water levels in a high-resolution digital elevation model. The consistent spatial and temporal relationships between the statistical moments of the waterbody size distributions underscore the dominance of topographic controls in lowland permafrost areas. These results provide motivation for further analyses of the factors involved in waterbody development and spatial distribution and for investigations into the possibility of using statistical moments to predict future hydrologic dynamics in the Arctic

    ESA GlobPermafrost - WebGIS based Visualisation of Remote Sensing Data

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    GIS server and desktop GIS technologies support scientific work at all levels, from data collection and data processing to data management and data visualisation. Here we present how the development and publication of scalable WebGIS data services supports the ESA DUE Globpermafrost (2016-2018), and the ESA CCI+ Permafrost (2018-2021) projects, specifically in the interaction with the permafrost community. Within ESA DUE programs, user feedback is essential to improve the remote sensing products. This is why ESA GlobPermafrost had to focus on methods and infrastructure for data presentation, and established PerSYS (Permafrost Information System). PerSYS became the ESA GlobPermafrost geospatial information service for publishing and visualisation of information and data products to the public. Data products are described and searchable in the PerSYS Data Catalogue, a core component of the Arctic Permafrost Geospatial Centre (APGC), established within the framework of ERC PETA-CARB at AWI. All GlobPermafrost data products will be DOI-registered and archived in the data archive PANGAEA provided by AWI. The data visualisation employs AWI’s WebGIS-infrastructure maps@awi (http://maps.awi.de), a highly scalable data visualisation unit within AWI’s data workflow framework O2A (from Observation to Archive). GIS services have been created and designed using ArcGIS for Desktop (latest Version) and finally published as a Web Map Service (WMS), an internationally standardized format (Open Geospatial Consortium (OGC)), using ArcGIS for Server. The project-specific data WMS as well as a resolution-specific background map WMS are embedded into a GIS viewer application based on Leaflet, an open-source JavaScript library. The GIS viewer application was adapted to interlink all GlobPermafrost WebGIS projects, and especially to enable their direct accessibility via the GlobPermafrost Overview WebGIS. The PerSys WebGIS is accessible via the GlobPermafrost project webpage and linked to the respective product groups as well as to maps@awi. WebGIS technology within maps@awi supports the project-specific visualisation of raster and vector data products of diverse spatial resolutions and remote sensing sources. This is a prerequisite for the visualisation of the wide range of GlobPermafrost remote sensing products like: Landsat multispectral index trends (Tasseled Cap Brightness, Greeness, Wetness; Normalized Vegetation Index NDVI), Arctic land cover (e.g., shrub height, vegetation composition), lake ice grounding, InSAR-based land surface deformation, rock glacier velocities and a spatially distributed permafrost model output with permafrost probability and ground temperature per pixel. All WebGIS projects are adapted to the products’ specific spatial scales. For example, the WebGIS ‘Arctic’ visualises the Circum-Artic products. Higher spatial resolution products for rock glacier movements are visualised on regional scales in the WebGIS projects ‘Alps’, ‘Andes’ or ‘Central Asia’. The PerSYS WebGIS also visualises the locations of the WMO GCOS ground monitoring networks of the permafrost community: the Global Terrestrial Network for Permafrost GTN-P managed by the International Permafrost Association IPA. The PerSYS WebGIS has been presented on several User workshops and at conferences, and is being continuously adapted in close interaction with the IPA

    PerSys - WebGIS-based permafrost data visualisation system for ESA GlobPermafrost

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    ESA DUE GlobPermafrost (www.globpermafrost.info) provides a remote sensing data service for permafrost research and applications. This service comprises of the generation of remote sensing products for various regions and spatial scales, and specific infrastructures for visualisation, dissemination and access to datasets. PerSys is the ESA GlobPermafrost geospatial information service for publishing and visualisation of information and data productstothepublic.DataproductsaredescribedandsearchableinthePerSysDataCatalogue,acorecomponent of the Arctic Permafrost Geospatial Centre (APGC), established within the framework of ERC PETA-CARB at AWI. The data visualisation employs the AWI WebGIS-infrastructure maps@awi (http://maps.awi.de), a highly scalable data visualisation unit within the AWI data-workflow framework O2A, from Observation to Archive. WebGIS technology in maps@awi supports the project-specific visualisation of raster and vector data products of diverse spatial resolutions and remote sensing sources. This is a prerequisite for the visualisation of the wide range of GlobPermafrost remote sensing products like: Landsat multispectral index trends (Tasseled Cap Brightness, Greeness, Wetness; Normalized Vegetation Index NDVI), Arctic land cover (e.g., shrub height, vegetation composition), lake ice grounding, InSAR-based land surface deformation, rock glacier velocities and a spatially distributed permafrost model output with permafrost probability and ground temperature per pixel. All WebGIS projects are adapted to the products specific spatial scale. For example, the WebGIS ‘Arctic’ visualises the Circum-Artic products. Higher spatial resolution products for rock glacier movements are visualised on regional scales in the WebGIS projects ‘Alps’, ‘Andes’ and ‘Central Asia’. GIS services were created and designed using ArcGIS for Desktop (10.4) and finally published as a Web MapService(WMS),aninternationallystandardizedformat(OpenGeospatialConsortium(OGC)),usingArcGIS for Server (10.4). The project-specific data WMS as well as a resolution-specific background map WMS are embedded into a GIS viewer application based on Leaflet, an open-source JavaScript library. The GIS viewer application was adapted to interlink all WebGIS projects, and especially to enable their direct accessibility via the GlobPermafrost Overview WebGIS project. The PerSys WebGIS is accessible via the GlobPermafrost project webpage and linked to the respective product groups as well as on maps@awi (maps.awi.de). All GlobPermafrost data products will be DOI-registered and archived in PANGAEA. In future, PerSys intends to encourage permafrost researchers other than GlobPermafrost to integrate and visualise their dat

    Adrenal tropism of SARS-CoV-2 and adrenal findings in a post-mortem case series of patients with severe fatal COVID-19

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    Progressive respiratory failure and hyperinflammatory response is the primary cause of death in the coronavirus disease 2019 (COVID-19) pandemic. Despite mounting evidence of disruption of the hypothalamus-pituitary-adrenal axis in COVID-19, relatively little is known about the tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to adrenal glands and associated changes. Here we demonstrate adrenal viral tropism and replication in COVID-19 patients. Adrenal glands showed inflammation accompanied by inflammatory cell death. Histopathologic analysis revealed widespread microthrombosis and severe adrenal injury. In addition, activation of the glycerophospholipid metabolism and reduction of cortisone intensities were characteristic for COVID-19 specimens. In conclusion, our autopsy series suggests that SARS-CoV-2 facilitates the induction of adrenalitis. Given the central role of adrenal glands in immunoregulation and taking into account the significant adrenal injury observed, monitoring of developing adrenal insufficiency might be essential in acute SARS-CoV-2 infection and during recovery.</p

    Development and validation of a multimodal neuroimaging biomarker for electroconvulsive therapy outcome in depression: A multicenter machine learning analysis

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    Background Electroconvulsive therapy (ECT) is the most effective intervention for patients with treatment resistant depression. A clinical decision support tool could guide patient selection to improve the overall response rate and avoid ineffective treatments with adverse effects. Initial small-scale, monocenter studies indicate that both structural magnetic resonance imaging (sMRI) and functional MRI (fMRI) biomarkers may predict ECT outcome, but it is not known whether those results can generalize to data from other centers. The objective of this study was to develop and validate neuroimaging biomarkers for ECT outcome in a multicenter setting. Methods Multimodal data (i.e. clinical, sMRI and resting-state fMRI) were collected from seven centers of the Global ECT-MRI Research Collaboration (GEMRIC). We used data from 189 depressed patients to evaluate which data modalities or combinations thereof could provide the best predictions for treatment remission (HAM-D score ⩽7) using a support vector machine classifier. Results Remission classification using a combination of gray matter volume and functional connectivity led to good performing models with average 0.82–0.83 area under the curve (AUC) when trained and tested on samples coming from the three largest centers (N = 109), and remained acceptable when validated using leave-one-site-out cross-validation (0.70–0.73 AUC). Conclusions These results show that multimodal neuroimaging data can be used to predict remission with ECT for individual patients across different treatment centers, despite significant variability in clinical characteristics across centers. Future development of a clinical decision support tool applying these biomarkers may be feasible.publishedVersio

    Effective resting-state connectivity in severe unipolar depression before and after electroconvulsive therapy

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    Background Electroconvulsive therapy (ECT) is one of the most effective treatments for severe depressive disorders. A recent multi-center study found no consistent changes in correlation-based (undirected) resting-state connectivity after ECT. Effective (directed) connectivity may provide more insight into the working mechanism of ECT. Objective We investigated whether there are consistent changes in effective resting-state connectivity. Methods This multi-center study included data from 189 patients suffering from severe unipolar depression and 59 healthy control participants. Longitudinal data were available for 81 patients and 24 healthy controls. We used dynamic causal modeling for resting-state functional magnetic resonance imaging to determine effective connectivity in the default mode, salience and central executive networks before and after a course of ECT. Bayesian general linear models were used to examine differences in baseline and longitudinal effective connectivity effects associated with ECT and its effectiveness. Results Compared to controls, depressed patients showed many differences in effective connectivity at baseline, which varied according to the presence of psychotic features and later treatment outcome. Additionally, effective connectivity changed after ECT, which was related to ECT effectiveness. Notably, treatment effectiveness was associated with decreasing and increasing effective connectivity from the posterior default mode network to the left and right insula, respectively. No effects were found using correlation-based (undirected) connectivity. Conclusions A beneficial response to ECT may depend on how brain regions influence each other in networks important for emotion and cognition. These findings further elucidate the working mechanisms of ECT and may provide directions for future non-invasive brain stimulation research.publishedVersio

    Effective resting-state connectivity in severe unipolar depression before and after electroconvulsive therapy

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    BACKGROUND: Electroconvulsive therapy (ECT) is one of the most effective treatments for severe depressive disorders. A recent multi-center study found no consistent changes in correlation-based (undirected) resting-state connectivity after ECT. Effective (directed) connectivity may provide more insight into the working mechanism of ECT. OBJECTIVE: We investigated whether there are consistent changes in effective resting-state connectivity. METHODS: This multi-center study included data from 189 patients suffering from severe unipolar depression and 59 healthy control participants. Longitudinal data were available for 81 patients and 24 healthy controls. We used dynamic causal modeling for resting-state functional magnetic resonance imaging to determine effective connectivity in the default mode, salience and central executive networks before and after a course of ECT. Bayesian general linear models were used to examine differences in baseline and longitudinal effective connectivity effects associated with ECT and its effectiveness. RESULTS: Compared to controls, depressed patients showed many differences in effective connectivity at baseline, which varied according to the presence of psychotic features and later treatment outcome. Additionally, effective connectivity changed after ECT, which was related to ECT effectiveness. Notably, treatment effectiveness was associated with decreasing and increasing effective connectivity from the posterior default mode network to the left and right insula, respectively. No effects were found using correlation-based (undirected) connectivity. CONCLUSIONS: A beneficial response to ECT may depend on how brain regions influence each other in networks important for emotion and cognition. These findings further elucidate the working mechanisms of ECT and may provide directions for future non-invasive brain stimulation research
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