High-resolution computed microtomography for the characterization of a diffusion tensor imaging phantom     

Łukasz Kaczmarek  Tomasz Wejrzanowski  Jakub Skibiński  Michał Maksimczuk  Artur Krzyżak 《Acta Geophysica》2017,65(1):259-268

This paper addresses the issue of the quantitative characterization of the structure of the calibration model (phantom) for b-matrix spatial distribution diffusion tensor imaging (BSD-DTI) scanners. The aim of this study was to verify manufacturing assumptions of the structure of materials, since phantoms are used for BSD-DTI calibration directly after manufacturing. Visualization of the phantoms’ structure was achieved through optical microscopy and high-resolution computed microtomography (µCT). Using µCT images, a numerical model of the materials structure was developed for further quantitative analysis. 3D image characterization was performed to determine crucial structural parameters of the phantom: porosity, uniformity and distribution of equivalent diameter of capillary bundles. Additionally calculations of hypothetical flow streamlines were also performed based on the numerical model that was developed. The results obtained in this study can be used in the calibration of DTI-BST measurements. However, it was found that the structure of the phantom exhibits flaws and discrepancies from the assumed geometry which might affect BSD-DTI calibration.  相似文献   

Sediment detachment in piping-prone soils: Cohesion sources and potential weakening mechanisms     

Anita Bernatek-Jakiel  Jiří Bruthans  Jan Vojtíšek  Mateusz Stolarczyk  Tomasz Zaleski 《地球表面变化过程与地形》2020,45(13):3185-3201

Soil piping is a widespread land degradation process that may lead to gully formation. However, the processes involved in sediment detachment from soil pipe walls have not been well studied, although their recognition is a crucial step to protect soils from piping erosion. This study aims to recognize the factors affecting cohesion and to identify the mechanisms which are likely to be responsible for the disintegration of soil. The study has been conducted in mid-altitude mountains under a temperate climate (the Bieszczady Mountains, the Carpathians, SE Poland). The research was based on the detailed field and laboratory analyses of morphology, and the physical and chemical properties of soil profiles with and without soil pipes. Moreover, experiments with flooding the undisturbed soil samples using different solutions (deionized water, ammonium oxalate, dithionate citrate, 35% hydrochloric acid and 30% hydrogen peroxide) were conducted in order to check the role of air slaking, the removal of soil organic carbon (SOC), and Fe and Al oxides on sediment detachment. The obtained results have confirmed that soil pipes develop in quite cohesive soils (silt loams), which allow the formation and maintenance of pipes with a diameter up to 30 cm. Soil cohesion, and thus susceptibility to piping, are impacted by the content of major oxides, soil particle size distribution, biological activity and porosity. The tested soils affected by piping erosion have a lower content of Al₂O₃ and Fe₂O₃, and free Fe (Fe_(DCB)), lower clay content, higher biological activity (more roots and animal burrows), higher porosity, and more and larger pores than the profile without soil pipes. The experiments have indicated that especially SOC along with Fe and Al oxides are an important cohesion source in the study area. This suggests that the removal of SOC, and Fe and Al oxides may weaken and disintegrate aggregates in soil pipes. Further study of soil leaching and tensile strength will broaden understanding of which chemical processes control where pipes will develop in other cohesive piping-prone soils. © 2020 John Wiley & Sons, Ltd.  相似文献   

History and regional development. A controversy over the ‘right’ interpretation of the role of history in the development of the Polish regions     

Tomasz Zarycki 《Geoforum》2007,38(3):485-493

There is currently a lively discussion on the role of historic memories and the re-visiting of historic legacies in post-communist countries. Using the example of Poland and its legacy of the tripartite division of the 19th century, this paper aims to illustrate how symbolic conflicts over identity politics and the interpretation of history may critically influence discourses on the debates on, and portrayals of, variations in regional development. The paper thus discusses the post-war history of Poland in the context of the so-called left-right political cleavage, and the varying related debates on the ‘quality’ of regional development as part of Poland’s post-communist restructuring. These discussions include varying projections of the nature and role of social capital and its relative ‘usefulness’ for a successful development Poland’s after communism. And there are clear political overtones to these contrasting portrayals of Poland’s history and its regionally varying legacy. Drawing on different definitions of the notion of social capital, the paper then discusses how different legacies, such as an introspective and extrovert outlook of population and institutions, and the degree of cohesion among them, circumscribes a region’s economic development prospects.  相似文献   

Identification of seismic anomalies caused by gas saturation on the basis of theoretical P and PS wavefield in the Carpathian Foredeep,SE Poland     

Kaja Pietsch  Paweł Marzec  Marcin Kobylarski  Tomasz Danek  Andrzej Leśniak  Artur Tatarata  Edward Gruszczyk 《Acta Geophysica》2007,55(2):191-208

The thin-layer build of the Carpathian Foredeep Miocene formations and large petrophysical parameter variation cause seismic images of gas-saturated zones to be ambiguous, and the location of prospection wells on the basis of anomalous seismic record is risky. A method that assists reservoir interpretation of standard recorded seismic profiles (P waves) can be a converted wave recording (PS waves). This paper presents the results of application of a multicomponent seismic survey for the reservoir interpretation over the Chałupki Dębniańskie gas deposit, carried out for the first time in Poland by Geofizyka Kraków Ltd. for the Polish Oil and Gas Company. Seismic modeling was applied as the basic research tool, using the SeisMod program based on the finite-difference solution of the acoustic wave equation and equations of motion. Seismogeological models for P waves were developed using Acoustic Logs; S-wave model (records only from part of the well) was developed on the basis of theoretical curves calculated by means of the Estymacja program calibrated with average S-velocities, calculated by correlation of recorded P and PS wavefields with 1D modeling. The conformity between theoretical and recorded wavefields makes it possible to apply the criteria established on the basis of modeling for reservoir interpretation. Direct hydrocarbon indicators (bright spots, phase change, time sag) unambiguously identify gas-prone layers within the ChD-2 prospect. A partial range of the indicators observed in the SW part of the studied profile (bright spot that covers a single, anticlinally bent seismic horizon) points to saturation of the horizon. The proposed location is confirmed by criteria determined for converted waves (continuous seismic horizons with constant, high amplitude) despite poorer agreement between theoretical and recorded wavefields.  相似文献   

Reconstructing cosmic peculiar velocities from the mildly non-linear density field     

Andrzej Kudlicki  Micha&#; Chodorowski  Tomasz Plewa  Micha&#; Ró&#;yczka 《Monthly notices of the Royal Astronomical Society》2000,316(3):464-472

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Pleistocene sandur rhythms,cycles and megacycles: Interpretation of depositional scenarios and palaeoenvironmental conditions     

Małgorzata Pisarska‐Jamroży  Tomasz Zieliński 《Boreas: An International Journal of Quaternary Research》2014,43(2):330-348

The Drawa sandur, which is the largest, coarse‐grained sandur in Poland, dates from the Pomeranian phase of the Weichselian glaciation (c. 16 ka BP). Using Markov chain analysis we infer that five cycles and five rhythms occur in its proximal part. The cycles dominated by Gt and St lithofacies in the lower part of the sandur succession and by a GDm lithofacies in the upper part, are fining‐upward cycles deposited in braided channels during large ablation floods. Three groups of cycles are distinguished based on their genesis: (i) cycles due to channel‐sheet evolution during large floods; (ii) cycles due to braid‐bar development during initial and advanced diminishing of floods; and (iii) cycles developed in the thalweg or interbar channels. The succession as a whole forms a large‐scale coarsening‐up megacycle (‘sandur megacycle’) which corresponds to a phase of ice‐sheet advance. Because the cyclicity was evident from Markov chain analysis of the sedimentary succession, we suggest that this statistical tool is valuable for reconstruction of glacifluvial sedimentary conditions, particularly as it can shed new light on the palaeogeographical development of sandar.  相似文献   

Book Review     

Tomasz Niedzielski 《Pure and Applied Geophysics》2011,168(5):957-959

The objective of the work discussed in this paper was to seek possible links between surface hydrology in Southwestern (SW) Poland and El Ni?o/Southern Oscillation (ENSO). Although the impact of ENSO on hydrology in Europe has been investigated by many researchers, no clear picture demonstrating spatial variability of such a teleconnection has yet been unequivocally reported. In particular, there is no comprehensive study on ENSO–streamflow links for Polish rivers. Herein, discharge time series from 15 sites located at lowland and mountain rivers in SW Poland and different ENSO indices are examined. They include atmospheric time series (axial component of atmospheric angular momentum, Southern Oscillation Index), oceanic indices (Ni?o 3.4 Index, Global SST Index), geodetic data (length-of-day), and the combined index (Multivariate ENSO Index). The data span the period from November 1971 to October 2006. On the basis of cross-correlation and wavelet analyses it was found that there is a weak but significant link between ENSO and surface hydrology in SW Poland. It is inferred that ENSO episodes may be among a few factors affecting winter and early spring discharges of rivers in SW Poland and may have a (probably limited) impact on snow-melt flood generation.  相似文献   

Do choropleth maps linked with parallel coordinates facilitate an understanding of multivariate spatial characteristics?     

Tomasz Opach  Jan Ketil Rød 《制图学和地理信息科学》2013,40(5):413-429

Our study has three objectives. We want to investigate (1) whether choropleth maps linked with parallel coordinates help people understand the locations of vulnerable places and the factors making these places vulnerable, (2) whether sparklines that imitate the polylines from a parallel coordinate plot support the understanding of the information provided in that plot, and (3) whether a multiple-view geovisualization approach might be intuitive and useful also for nonexperts. Although we base our work on the functionalities available in the tool called ‘ViewExposed,’ we intend to outline more general conclusions on whether multiple linked views facilitate the understanding of multivariate spatial characteristics. An empirical study with 53 individuals was conducted to obtain insights on these objectives. Our task-based assessment considered the ways in which participants understood the dynamic linking capabilities. Some of the key findings are as follows: (1) even nonexpert users are able to use parallel coordinates linked with choropleth maps; however, only those with extensive inference-making abilities will do so efficiently; (2) parallel coordinates sparklines work as an independent component facilitating the understanding of multivariate data; and (3) the intuitive nature of a multiple-view geovisualization tool is not enough to encourage people to use it.  相似文献   

Studies of aerosols advected to coastal areas with the use of remote techniques     

Tymon Zieliński  Tomasz Petelski  Przemysław Makuch  Agata Strzałkowska  Agnieszka Ponczkowska  Krzysztof M. Markowicz  Georgius Chourdakis  George Georgoussis  Susanne Kratzer 《Acta Geophysica》2012,60(5):1359-1385

This paper presents the results of the studies of aerosol optical properties measured using lidars and sun photometers. We describe two case studies of the combined measurements made in two coastal zones in Crete in 2006 and in Rozewie on the Baltic Sea in 2009. The combination of lidar and sun photometer measurements provides comprehensive information on both the total aerosol optical thickness in the entire atmosphere as well as the vertical structure of aerosol optical properties. Combination of such information with air mass back-trajectories and data collected at stations located on the route of air masses provides complete picture of the aerosol variations in the study area both vertically and horizontally. We show that such combined studies are especially important in the coastal areas where depending on air mass advection directions and altitudes the influence of fine or coarse mode (in this case possibly sea-salt) particles on the vertical structure of aerosol optical properties is an important issue to consider.  相似文献   

Study of vertical structure of aerosol optical properties with sun photometers and ceilometer during the MACRON campaign in 2007     

Krzysztof M. Markowicz  Tymon Zieliński  Sandra Blindheim  Michael Gausa  Anna K. Jagodnicka  Aleksandra E. Kardas  Wojciech Kumala  Szymon P. Malinowski  Tomasz Petelski  Michał Posyniak  Tadeusz Stacewicz 《Acta Geophysica》2012,60(5):1308-1337

This paper presents the measurements of a vertical structure of aerosol optical properties performed during the MACRON (Maritime Aerosol, Clouds and Radiation Observation in Norway) campaign, which took place in July and August 2007 at ALOMAR observatory on Andøya island (69.279°N, 16.009°E, elevation 380 m a.s.l.). The mean value of the aerosol optical thickness (AOT) at 500 nm during campaign was 0.12. Significant increase of the AOT above longtime mean value was observed on 7 and 8 August 2007 when the AOT exceeded 0.4 at 500 nm. Analyses of back trajectories show the aerosol transported from over Africa and Central Europe. The aerosol extinction coefficient obtained from the synergy of ceilometer and sun photometer observations reached 0.05–0.08 km^?1 (at 1064 nm) in the dust layer. The single scattering albedo at the ALOMAR observatory decreased during the dust episode to 0.93–0.94, which indicates some absorptive aerosols in the lower PBL.  相似文献